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Justia Patents Acoustic Wave Type Generator Or ReceiverUS Patent for Multilayer electrostrictive element which withstands repeated application of pulses Patent (Patent # 4,523,121)
Multilayer electrostrictive element which withstands repeated application of pulses
May 11, 1983 - NEC Corporation
A multilayer electrostrictive element has electrostrictive sections (31) defined by internal electrodes (32) in a stack, with a peripheral surface which has a predetermined outline perpendicularly of an axis of the stack, each internal electrode with an outline which is approximately congruent with the predetermined outline (constant cross-section). In order that external electrodes (33, 34) may readily be connected to the internal electrodes grouped by twos, each internal electrode may have a peripheral end which is partly recessed from the predetermined outline, as in FIG. 8. Alternatively, the internal electrodes of each group may be connected together by a conductor rod which passes through the electrostrictive sections, preferably along their edges, contacting alternate electrodes. For a great number of internal electrodes, an element may be manufactured by laminating conductive-paste-printed green sheets transversely of the stack axis and then sintering the lamination. Each internal electrode may include a ceramic material, such as an electrostrictive material of the electrostrictive sections, another electrostrictive material of a lower sintering temperature, or glass.
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This invention relates to an electrostrictive element or transducer of a multilayer structure which is generally called a stacked chip or ceramic capacitor structure in the art. An electrostrtictive element according to this invention is specifically useful in, among others, a printer head of an impact printer or a relay.
As described in a report contributed by Roderic Beresford to "Electronics," Nov. 3, 1981, pages 39 and 40, under the title of "Piezoelectric bender actuates tiny relays and dot-matrix printers," an electrostrictive element is useful as a printer head, a relay, or the like. An electrostrictive element is actuated by a d.c. voltage repeatedly supplied as voltage pulses when used in such fields of application. The element must withstand repeated application of such voltage pulses. In other words, the element must have a long life when a great number of voltage pulses are applied. Furthermore, it is desirable that the element give rise to a large displacement.
An electrostrictive element of a simplest type comprises an electrostrictive piece of a material capable of exhibiting a strong electrostrictive effect having a pair of electrodes on respective principal surfaces. When a d.c. voltage is supplied between the electrodes to produce an electic field, the electrostrictive material elongates and contracts in both the direction of the electric field and transversely. Such deformations or strains in the direction of the electric field and in the transverse direction are called the longitudinal and the transverse electrostrictive effects, respectively. It is known that the longitudinal electrostrictive effect ordinarily gives rise to two to three times as great a deformation as the transverse electrostrictive effect. The longitudinal electrostrictive effect therefore provides a higher efficiency of conversion from electric energy to mechanical energy. The deformation in the longitudinal or the transverse direction depends on the field intensity of the electric field produced in the electrostrictive piece.
When the transverse electrostrictive effect is used, it is possible with a certain applied voltage to achieve a displacement in the transverse direction which is proportional to the transverse dimension of the electrostrictive piece. When the longitudinal electrostrictive effect is used in order to take advantage of its higher efficiency of energy conversion, the displacement in the longitudinal direction does not grow for a given voltage with an increase in the dimension which the piece has in the longitudinal direction. This is because the field intensity becomes weak as the longitudinal dimension increases. It is therefore necessary, for attaining a great displacement with the longitudinal electrostrictive effect, to raise the applied voltage, so as to strengthen the field intensity. A power source for a high voltage is, however, bulky and expensive. Furthermore, a high voltage is objectionable in view of the danger inevitable during operation of the electrostrictive element and also in view of the withstanding voltage of IC's which are used in a driving circuit for the element. The element is therefore given the multilayer structure when the longitudinal electrostrictive effect is used.
As will later be described in detail with reference to two of nearly thirty figures of the accompanying drawings, a multilayer electrostrictive element comprises a plurality of electrostrictive sections defined in a stack or lamination by a plurality of internal electrodes which are perpendicular to an axis of the stack. The stack has a peripheral surface which has a predetermined outline perpendicularly to the axis. For use in a printer head or a relay, it is preferred that the predetermined outline be four sides of a rectangle. A first external electrode is connected to alternate ones of the internal electrodes and is placed externally of the peripheral surface. A second external electrode is connected to others of the internal electrodes and is positioned externally of the peripheral surface. At least one of the first and the second external electrodes may be extended in contact with the peripheral surface. Even in this event, it is possible to understand that the external electrode or electrodes are situated externally of the peripheral surface.
With a multilayer electrostrictive element, a great displacement is achieved at a low voltage even by the use of the longitudinal electrostrictive effect. It is to be noted here that each internal electrode has an internal electrode outline which is positioned only partly on the peripheral surface for connection to the first or the second external electrode. In other words, each internal electrode has an internal electrode area which is considerably narrower than a cross-sectional area of the stack. As will later be discussed with reference to several figures of the accompanying drawing, it has now been confirmed that this results in a short life which the electrostrictive element has when repeatedly supplied with voltage pulses. Moreover, this restricts the displacement, as compared with the displacement which is theoretically attainable.
It is therefore an object of the present invention to provide a multilayer electrostrictive element which has a long life, even when voltage pulses are repeatedly applied to drive the element.
It is another object of this invention to provide an electrostrictive element of the type described, which provides a greater displacement as compared with that achieved by conventional electrostrictive elements.
Other objects of this invention will become clear as the description proceeds.
An electrostrictive element to which this invention is applicable comprises a plurality of electrostrictive sections of an electrostrictive material defined in a stack by a plurality of internal electrodes which are perpendicular to an axis of the stack, first means for electrically connecting alternate ones of the internal electrodes together, and second means for electrically connecting others of the internal electrodes togther. The stack has a peripheral surface which has a predetermined outline perpendicularly of the axis. According to this invention, each internal electrode is given a peripheral end of an internal electrode outline which is approximately congruent with the predetermined outline.
According to an aspect of this invention, each internal electrode has an internal electrode area which is equal to a cross-sectional area of the stack with the peripheral ends of the respective internal electrodes positioned on the peripheral surface, which has the predetermined outline throughout the stack.
According to another aspect of this invention, each internal electrode has an internal electrode area perpendicularly of the axis, which area is narrower than a cross-sectional area of the stack, in an electrostrictive element wherein the peripheral surface has the predetermined outline throughout the stack.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic longitudinal sectional view of a conventional electrostrictive element;
FIG. 2 is a top view of the electronstrictive element illustrated in FIG. 1;
FIG. 3 is a schematical longitudinal sectional view of an electrostrictive element according to a first embodiment of the instant invention;
FIG. 4 is a top view of the electrostrictive element depicted in FIG. 3;
FIG. 5 shows the life for conventional electrostrictive elements and for electrostrictive elements of the type shown in FIGS. 3 and 4;
FIG. 6 shows the displacement attained by the electrostrictive elements mentioned in connection with FIG. 5;
FIG. 7 schematically and partially shows a perspectively exploded view of an electrostrictive element according to a second embodiment of this invention;
FIG. 8 is a top view of the electrostrictive element illustrated in FIG. 7;
FIG. 9 schematically and partially shows a perspectively exploded view of an electrostrictive element according to a modification of the element depicted to FIGS. 7 and 8;
FIG. 10 is a top view of an electrostrictive element according to another modification of the element illustrated in FIGS. 7 and 8;
FIG. 11 is a schematic top view of an electrostrictive element according to a third embodiment of this invention;
FIG. 12 shows the life for conventional electrostrictive elements and for electrostrictive elements of the structure depicted in FIG. 11;
FIG. 13 shows the displacement achieved by the elements mentioned in conjunction with FIG. 12;
FIG. 14 is a schematic longitudinal sectional view of an electrostrictive element according to a fourth embodiment of this invention;
FIG. 15 is a schematic top view of a green sheet piece for use in manufacturing the element shown in FIG. 14;
FIG. 16 is a schematical longitudinal sectional view of an electrostrictive element according to a fifth embodiment of this invention;
FIG. 17 is a top view of the element illustrated in FIG. 16;
FIG. 18 as a schematic top view of a green sheet piece for use in manufacturing the element of the type depicted in FIGS. 16 and 17;
FIG. 19 is a schematic side view of an electrostrictive element according to a sixth embodiment of this invention;
FIG. 20 shows the life for conventional electrostrictive elements and for electrostrictive elements of the type depicted in FIG. 19;
FIG. 22 is a schematical longitudinal sectional view of an electrostrictive element according to a seventh embodiment of this invention;
FIG. 23 is a schematical longitudinal sectional view of an electrostrictive element according to an eighth embodiment of this invention;
FIG. 24 is a schematic perspective view of an electrostrictive element according to a ninth embodiment of this invention;
FIG. 25 shows the life for electrostrictive elements according to a tenth embodiment of this invention;
FIG. 26 shows the displacement attained by the elements mentioned in connection with FIG. 25;
FIG. 27 shows the life for electrostrictive elements according to an eleventh embodiment of this invention and for the elements mentioned in connection with FIGS. 25 and 26;
FIG. 28 shows the life for electrostrictive elements according to a twelfth embodiment of this invention; and
FIG. 29 shows the displacement achieved by the elements mentioned in conjunction with FIG. 28.
Referring to FIGS. 1 and 2, a conventional multilayer electrostrictive element or transducer will be described at first in order to facilitate an understanding of the present invention, although the claims are directed primarily to FIG. 22. The element comprises a stack or lamination of a plurality of electrostrictive sections or segments 31 of an electrostrictive material capable of exhibiting a strong electrostrictive effect. The electrostrictive sections 31 are defined in the stack by a plurality of internal electrodes 32 which are indicated by thick lines and are disposed perpendicular to an axis of the stack with a predetermined spacing. Although called "internal electrodes," the electrodes 32 may be placed on one or both of the top and the bottom surfaces of the stack. The stack has a peripheral surface whose cross section defines a predetermined outline. In the example being illustrated, the predetermined outline consists of four sides of a rectangle. The peripheral surface has the predetermined outline throughout the stack (i.e. the stack has a constant cross-section). It is possible to render the predetermined spacing (between electrodes 32) as small as several microns.
As seen from FIGS. 1 and 2, each internal electrode 32 has an end lying on the peripheral surface of the stack. More particularly, alternate ones of the internal electrodes 32 have their respective ends on one of four side surfaces of the stack. Others of the internal electrodes 32 have the ends on an opposing side surface of the stack as outlined by dashed lines in FIG. 2. A first external electrode 33 is formed on the first-mentioned side surface, in contact with the ends of the alternate ones of the internal electrodes 32. A second external electrode 34 is formed on the opposing side surface, in contact with the ends of the others of the internal electrodes 32. First and second electrode terminals 36 and 37 are connected to the first and the second external electrodes 33 and 34, respectively.
When a d.c. voltage is supplied between the electrode terminals 36 and 37, electric fields are produced in the respective electrostrictive sections 31. The electrostrictive element elongates axially of the stack. When a d.c. voltage pulse is repeatedly applied to the element a great number of times, the element is mechanically damaged, particularly if the voltage is raised to achieve a great displacement. Furthermore, the elongation or displacement of the element is appreciably small as compared with the elongation which should theoretically be attained.
As will later be evidenced by various examples in comparison with references, it has now been confirmed that such defects of a conventional electrostrictive element result from the fact that an area on which the internal electrodes 32 are superposed is considerably narrower than a cross-sectional area of the stack. More specifically, the electric field is produced in each electrostrictive section 31 substantially only at a central portion between the opposing internal electrodes 32. The electric field is weak at a peripheral portion surrounding the central portion. The elongation therefore takes place at such central portions of the respective electrostrictive sections 31 and hardly occurs at the peripheral portions. The elongation of the element as a whole is consequently adversely affected by the peripheral portions. Moreover, concentration of the stress takes place along the boundary between the central and the peripheral portions. This results in cracks or other mechanical damage when a large number of voltage pulses are applied to the element.
Referring now to FIGS. 3 and 4, an electrostrictive element according to a first embodiment of this invention comprises similar parts as those in FIGS. 1 and 2, such parts being designated by like reference numerals. The peripheral end of each internal electrode 32, however, has an outline which is congruent with the outline which the peripheral surface of the stack has perpendicularly of the stack axis. The peripheral ends of the respective internal electrodes 32 are positioned on the peripheral surface of the stack. Furthermore, each internal electrode 32 has an internal electrode area which is equal to the cross-sectional area of the stack. A first external electrode 33 is positioned externally of the peripheral surface of the stack and is brought into contact with the peripheral ends of alternate ones of the internal electrodes 32. A second external electrode 34 is laid outwardly of the peripheral surface of the stack and connected to the peripheral ends of the remaining internal electrodes 32.
As Example I, electrostrictive elements of the structure illustrated with reference to FIGS. 3 and 4, were manufactured as follows. At first, a slurry was prepared by suspending a mixture of presintered powder of a solid solution of lead magnesium niobate Pb(Mg.sub.1/3 Nb.sub.2/2)O.sub.3 and lead titanete PbTiO.sub.3 in a mol ratio of 9 to 1 and an organic binder, in an organic solvent in the manner known in the art. The presintering was carried out at 800.degree. C. for two hours. It is known that a sintered piece of the solid solution exhibits a strong electrostrictive effect. The slurry was applied onto a polyester film known as a Mylar film by the doctor blade method to a thickness of several hundreds of microns and then dried. The green sheet thus formed, was peeled off the polyester film and subsequently cut into green sheet pieces of a predetermined size. Platinum paste was printed to form a platinum paste layer on a surface of each green sheet piece. The green sheet pieces with the printed platinum paste layers, were stacked, rendered integral in a hot press, machined to predetermined dimensions to expose the peripheral ends of the respective platinum paste layers on the peripheral surface of each integral stack, and subsequently sintered at about 1200.degree. C. for one hour. The green sheet pieces became the electrostrictive sections 31 (FIG. 3). Fired layers of the platinum paste became the internal electrodes 32.
Having been machined to the predetermined dimensions, each integral stack had a square cross section of 3 mm by 3 mm and a height of 10 mm. The spacing between two adjacent ones of the internal electrodes 32 was 250 microns. Lead wires were soldered to the peripheral ends of the respective internal electrodes 32 so as to serve as the first and the second external electrodes 33 and 34 and so that a pair of ends of the respective lead wires serve as the first and the second electrode terminals 36 and 37.
As Reference I, electrostrictive elements of the conventional structure illustrated with reference to FIGS. 1 and 2, were likewise manufactured. An area on which the internal electrodes 32 were superposed, was 84% of the cross-sectional area of the stack. The external electrodes 33 and 34 were formed by applying silver paste onto the side surfaces and then firing the paste.
Turning now to FIG. 5, a pulse sequence was continuously applied to each of the electrostrictive elements of Example I and of Reference I. Each pulse was a half of a sinusoidal wave of an amplitude of 250 volts. Each pulse had a pulse width of 1 millisecond. As shown by an upper line 41, the elements of Example I showed a maximum displacement of 4.1 microns. A lower curve 42 represents that the elements of Reference I showed a maximum displacement of only 1.3 microns. Each element of Example I was not damaged or broken even when the pulses were applied one hundred million times or repetitions as shown by the upper line 41. Each element of Reference I was damaged as indicated by a cross when the pulses were applied about twenty-five thousand times.
Turning further to FIG. 6, a d.c. voltage was applied to each of the electrostrictive elements of Example I and of Reference I. Displacements were measured with the voltage varied. As is clear from upper and lower curves 43 and 44 for the elements of Example I and of Reference I, respectively, the elements of Example I showed two to three times as great a displacement as the elements of Reference I at a given voltage (and consequently at a given field intensity).
Referring to FIGS. 7 and 8, an electrostrictive element according to a second embodiment of this invention comprises similar parts designated by like reference numerals. Somewhat different from the internal electrodes 32 described in conjunction with FIGS. 3 and 4, each internal electrode 32 has a peripheral end of an internal electrode outline which is approximately congruent with the predetermined outline of the stack. Each internal electrode 32 has an internal electrode area which is a little narrower than the cross-sectional area of the stack. At any rate, the internal electrode outlines of the respective internal electrodes 32 are congruent with one another. More particularly, the peripheral end of each internal electrode 32 comprises a first and a second peripheral part. The first peripheral part is congruent with the predetermined outline except for the second peripheral part. The first peripheral parts of the respective internal electrodes 32 are situated on the peripheral surface of the cross-section of the stack. The second peripheral parts of alternate ones of the internal electrodes 32 are positioned in the stack so as to define a first area 46 on the peripheral surface. The second peripheral parts of others of the internal electrodes 32 likewise define a second area 47 on the peripheral surface. In the example being illustrated, the predetermined outline again consists of four sides of a rectangle. The second peripheral part of each internal electrode 32 is arcuately recessed from one of the four sides. Furthermore, the first and the second areas 46 and 47 are defined on opposing side surfaces of the stack. In any event, the first and the second external electrodes 33 and 34 are formed on the first and the second areas 46 and 47, respectively, like in the element illustrated with reference to FIGS. 1 and 2.
As Example II, electrostrictive elements were manufactured as described in conjunction with the elements of Example I except that each internal electrode 32 (FIG. 7) had an internal electrode area which was 92% of the cross-sectional area of the stack. Silver paste was applied in stripes onto the first and the second areas 46 and 47 and then fired into the first and the second external electrodes 33 and 34. The electrode terminals 36 and 37 were attached to the respective external electrodes 33 and 34.
The life tests and tests for the displacement were carried out for the electrostrictive elements of Example II and of Reference I as described in connection with FIGS. 5 and 6. The results were similar except that the maximum displacement was 4.0 microns and a little smaller than that attained by the elements of Example I.
Referring again to FIGS. 7 and 8, it is possible to form the first and the second areas 46 and 47 on two adjacent side surfaces of the stack. Alternatively, the second or arcuately recessed peripheral part may be offset along an outline which is congruent with the predetermined outline so that both the first and the second areas 46 and 47 may be formed on one of the four side surfaces of the stack. In any event, the predetermined outline may be circular, elliptic, or the like.
Turning to FIG. 9, the second peripheral part may be a short linear portion which intersects two adjacent sides of the predetermined outline of a rectangular shape. In the example being illustrated, the first area is formed on two adjacent side surfaces of the stack along an edge. The second area is similarly formed on two other side surfaces. As described in connection with FIGS. 7 and 8, the first and the second areas may be formed so as to share one of the four side surfaces in common. In this event, it is possible to form the first and the second external electrodes on that one of the side surfaces.
Turning further to FIG. 10, the second peripheral part may be a line which intersects opposing sides of the predetermined outline of a rectangle. It may appear that the electrostrictive element depicted in FIG. 10 is similar to the conventional element. The fact is quite different in that the first peripheral part of each internal electrode 32 is placed on a majority of the peripheral surface and in that the life is quite unexpectedly lengthened with the attainable displacement rendered astonishingly great.
Referring to FIG. 11, an electrostrictive element according to a third embodiment of this invention is similar in structure to that illustrated with reference to FIGS. 3 and 4 and that illustrated with reference to FIGS. 7 and 8 or FIG. 9 or 10 in that each internal electrode 32 has an internal electrode outline congruent with the predetermined outline of the stack and in that each internal electrode 32 has an internal electrode area which is smaller than the cross-sectional area of the stack. The internal electrode area is rendered small by forming at least one hole through each internal electrode 32. In the illustrated example, nine holes are formed in a matrix configuration in each internal electrode 32 of a square shape.
As Examples III, IV, and V, electrostrictive elements were manufactured as described in conjunction with the elements of Example I and with the internal electrode areas rendered 95%, 85%, and 70% of the cross-sectional area, respectively. The holes were readily formed by screen printing the platinum paste onto the surface of each green sheet piece. The first and the second external electrodes 33 and 34 (FIGS. 3 and 4) were formed by soldering a pair of lead wires to the peripheral ends of the respective internal electrodes 32 as described before.
Turning to FIG. 12, tests for the life and the maximum displacement were carried out for the electrostrictive elements of Examples III through V and of Reference I as described in connection with FIG. 5. The life and the maximum displacement are shown by lines 51, 52, and 53 for the elements of Examples III through V, respectivly, and by the line 42 for the elements of Reference I as above. Irrespective of the fact that each internal electrode area was smaller in the elements of Example V than the elements of Reference I, the line 53 shows an astonishingly long life with an appreciably greater maximum displacement.
Turning further to FIG. 13, displacements were measured as described in connection with FIG. 6. Curves 56, 57, and 58 show the results for the elements of Examples III through V, respectively. Despite the fact that each internal electrode area of the elements of Example IV was not much greater than that in the elements of Reference I, the curve 57 shows a considerably greater displacement than that depicted by the curve 44 for the elements of Reference I as in FIG. 6.
Referring to FIGS. 14 and 15, an electrostrictive element according to a fourth embodiment of this invention is similar to that described with reference to FIG. 11 in that each internal electrode 32 has a smaller hole 61 of a predetermined inside diameter and a greater hole 62 of a greater inside diameter as exemplified in FIG. 15. Each internal electrode outline is preferably congruent with the predetermined outline which the peripheral surface of the stack has perpendicularly of the stack axis. In the example being illustrated, the internal electrode outline consists of four sides of a square. Furthermore, the smaller and the greater holes 61 and 62 are positioned symmetrically on a line bisecting opposing sides of the square on both sides of another line bisecting other opposing sides. Each electrostrictive section 31 on which the internal electrode 32 is formed, has two holes in registration with the smaller and the greater holes 61 and 62. One of the holes formed through the electrostrictive section 31 has the predetermined inside diameter and indicated at 63. The outer hole of the electrostrictive section 31 also has the predetermined inside diameter.
As best shown in FIG. 14, electrostrictive sections 31 with such internal electrodes 32 are stacked so that the smaller and the greater holes of alternate ones of the internal electrodes 32 may be aligned with the greater and the smaller holes of others of the internal electrodes 32, respectively. A first conductor rod 64, which serves for the first external electrode 33 (FIG. 1 or 3), fills the smaller holes of the alternate ones of the internal electrodes 32 in contact with such internal electrodes 32 and passes through the greater holes of the other internal electrodes and those of the holes of the electrostrictive elements 31 which are aligned with the smaller holes of the alternate ones of the internal electrodes 32 and consequently with the greater holes of the other internal electrodes. Similarly, a second conductor rod 65 fills the smaller holes of the other internal electrodes in contact therewith and passes through the greater holes of the alternate ones of the internal electrodes 32 and the other holes of the electrostrictive sections 31 to serve for the second external electrode 34. In contrast to the external electrodes 33 and 34 of each electrostrictive element illustrated with reference to FIGS. 3 and 4, it is readily possible to stably connect the conductors 64 and 65 to the alternate ones of the internal electrodes 32 and to the other internal electrodes, respectively.
As Example VI, electrostrictive elements were manufactured with the structure described in conjunction with FIGS. 14 and 15. A pair of holes of a common inside diameter was drilled through each green sheet piece formed as described in connection with Example I. As depicted in FIG. 15, platinum paste was screen printed on the drilled green sheet piece to leave a blank area of a greater diameter around the hole 63 of the green sheet piece and was filled in the holes, such as 63, of each green sheet piece. As described in connection with Example I, the green sheet pieces with the printed and filling platinum paste were stacked, rendered integral, and then sintered. During the sintering process, the platinum paste filling the respective holes of the stacked green sheet pieces was fired into platinum rods to serve as the conductor rods 64 and 65. When the spacing between two adjacent internal electrodes 32 was 0.1 mm, it was confirmed that the predetermined inside diameter of 0.15 mm and the greater inside diameter of 0.6 mm were sufficient to readily and stably provide the conductors 64 and 65 without any short circuit between the successive internal electrodes 32. Incidentally, the elements had a square cross section of 10 mm by 10 mm.
Turning again to FIG. 15, it is not necessary that the smaller and the larger holes 61 and 62 be circular in shape. Regardless of the shape or shapes of the holes 61 and 62, the smaller hole 61 should have a smaller inside measure, which may be called a predetermined inside measure. The larger holes 62 should have a greater inside measure preferably in common. It is also unnecessary that the holes 61 and 62 be symmetrically situated on both sides of the center of the internal electrode 32. It is only necessary on manufacturing the stack of electrostrictive sections 31 that the smaller holes 61 of alternate ones of the internal electrodes 32 be aligned with the greater holes 62 of others of the internal electrodes 32 with the greater holes 62 of the alternate ones of the internal electrodes 32 aligned with the smaller holes 61 of the other internal electrodes. For example, it is possible to form the "holes" in each green sheet piece of a rectangular cross section by forming deeply arcuately recessed indents from one of the four sides of the rectangle.
FIGS. 16 and 17 are an electrostrictive element according to a fifth embodiment of this invention. It is possible to understand that the element being illustrated is similar to that described in connection with FIG. 11. More particularly, each internal electrode 32 has an internal electrode outline congruent with the predetermined outline which the peripheral surface of the stack as viewed along a plane perpendicular to the stack axis. A peripheral end of each internal electrode 32 is situated on the peripheral surface of the stack. An internal electrode area which the internal electrode 32 has orthogonally of the stack axis, is smaller than the cross-sectional area of the stack. The area is rendered narrow by a plurality of parallel holes formed through each internal electrode 32 with a common height parallel to the stack axis. For the reason which will presently become clear, the holes in the respective internal electrodes 32 are preferably aligned parallel to the stack axis. The electrostrictive sections 31 are continuous throughout the stack through the aligned holes.
More particularly referring to FIGS. 16 and 17, each internal electrode 32 comprises a plurality of internal electrode sections, each having a predetermined width parallel to the stack axis and a section end. The internal electrode sections of each internal electrode 32 are arranged at a predetermined distance. The internal electrode 32 preferably comprises a conductor piece 66 on the peripheral surface of the stack in contact with the section ends of the respective internal electrode sections. The conductor piece or pieces 66 provide a part of the peripheral end. The first external electrode 33 is formed by soldering or otherwise attaching a lead wire either to the conductor piece 66 of alternate ones of the internal electrodes 32 or to those of the internal electrode sections of the alternate ones of the internal electrodes 32 which are placed on the peripheral surface of the stack. The second external electrode 34 is similarly formed by connecting another lead wire to the peripheral ends of others of the internal electrodes 32. It is possible to form a pair of such conductor pieces in contact with both ends of each internal electrode section for each internal electrode 32.
FIG. 18 shows a green sheet piece 67 used in manufacturing an electrostrictive element of the structure illustrated in FIGS. 16 and 17. Platinum paste is printed in stripes on the green sheet piece as exemplified at 68. The element is manufactured by stacking a predetermined number, such as thirty sheets, of the green sheet pieces 67 with the platinum paste stripes 68, rendering the lamination integral in a hot press, and subsequently sintering the integral lamination. The platinum paste stripes 68 provide the internal electrode sections of the respective internal electrodes 32. The green sheet portions between layers of the internal electrode sections provide the electrostrictive sections 31 which are continuous as described above. The green sheet pieces 67 with the printed stripes 68 enable the element to be readily manufactured with a smaller number of green sheet pieces, as compared with the elements described in connection with Examples I through VI as will shortly become clear.
As Example VII, green sheet pieces were manufactured as in Example I. Each green sheet piece was about 3 mm wide, 10 mm long, and 100 microns thick. Platinum paste was screen printed on each green sheet piece. Each platinum paste stripe 68 (FIG. 18) had a width selected between 20 and 30 microns. Each blank area left between two adjacent platinum paste stripes 68 had a width which was selected between 20 and 30 microns. Thirty green sheet pieces with the printed stripes, were stacked for each electrostrictive element with the platinum paste stripes printed on both surfaces of the green sheet piece which was to be placed at an end of the lamination. It is to be noted in this connection that a stack and an axis of stack often referred to herein, should refer to a stack of the electrostrictive sections 31 (FIGS. 1, 3, and the like) rather than to a stack or lamination of the green sheet pieces 67 under consideration. The stacked green sheet pieces 67 were processed as described in connection with Example I. Silver paste was printed on the peripheral surface of each element and was fired into the conductor pieces 66 (FIG. 17). It was readily possible to manufacture an electrostrictive element in which a great number of electrostrictive sections 31 were defined between the internal electrodes 32.
FIG. 19 is an electrostrictive element according to a sixth embodiment of this invention. The internal structure may be similar to that described in connection with the conventional electrostrictive element with reference to FIGS. 1 and 2. It is, however, to be noted that those parts of the electrostrictive sections 31 (FIG. 1) are removed at selected heights of the stack which do not contribute to the electrostrictive effect. By way of example, indents or grooves 71 are formed on the peripheral surface. Each indent 71 may be formed along the whole periphery of the peripheral surface by a diamond cutter.
When attention is directed to a first peripheral part defined by the bottom of each indent 71, it is understood that the internal electrode outline of each internal electrode 32 (FIG. 1) is approximately congruent with an outline which the first peripheral part has perpendicular to the stack axis and which may again be called the predetermined outline. The peripheral surface further comprises second peripheral parts from which each indent 71 is recessed to define the first peripheral part. Each internal electrode 32 has an end on the second peripheral part, as will be understood from FIGS. 1 and 2. In order that even a part of the internal electrodes 32 may not be removed, it is preferred that each indent 71 be formed only partly along the periphery. For example, each indent 71 may be formed in two parts along the side surfaces depicted in FIG. 2 at the top and the bottom of the figure.
As Example VIII, electrostrictive elements were manufactured like the elements of Reference I except that indents were machined by a diamond cutter along the whole periphery after the first and the second external electrodes 33 and 34 (FIG. 19) were formed. Each indent 71 was 0.1 mm wide in the direction parallel to the stack axis and 0.1 mm deep perpendicularly of the axis. The center to center distance between two adjacent indents 71 was 2.0 mm. Parts into which the external electrodes 33 and 34 were divided by each indent 71, were connected together by lead wires. Each internal electrode area was 84% of the cross-sectional area which the above-described second peripheral parts had in common.
Turning to FIGS. 20 and 21, measurements were carried out for the life and the maximum displacement of the electrostrictive elements of Example VIII and of Reference I as described in connection with FIG. 5. The life was quite unexpectedly improved as shown by an upper line 72 for the elements of Example VIII. The maximum displacement was 1.9 microns and was a little improved as compared with that attained by the elements of Reference I and depicted by the lower line 42 as in FIG. 5.
As shown in FIG. 21, the dependency of displacement on the applied voltage was tested as described in conjunction with FIG. 6 for the elements of Example VIII and of Reference I. The results for the elements of Example VIII are illustrated by an upper curve 74. Those for the Reference I are shown by the lower curve 44 as in FIG. 6.
FIG. 22 is an electrostrictive element according to a seventh embodiment of this invention, similar to that illustrated with reference to FIGS. 3 and 4. The first external electrode 33 comprises first insulating layer portions 76 on a first area 46 (FIG. 8) to cover the respective peripheral ends of the above-mentioned others of the internal electrodes 32, leaving first area portions uncovered on the first area 46 between the insulating layer portions 76. The second external electrode 34 comprises second insulating layer portions 77 located on a second area 47 (FIG. 8) to cover the respective peripheral ends of the above-mentioned alternate ones of the internal electrodes 32 leaving second area portions on the second area 47 between the second insulating layer portions 77. The first external electrode 33 further comprises a first conductive layer 78 on the first insulating layer portions 76 and on the first area portions. The second external electrode 34 further comprises a second conductive layer 79 on the second insulating layer portions 77 and on the second area portions. It is possible with this to readily and stably form the first and the second external electrodes 33 and 34.
As Example IX, electrostrictive elements were manufactured like the elements of Example I. The internal structure was as described with reference to FIG. 22. The internal stack of green sheet pieces with prints was sintered at about 1250.degree. C. for one hour. Epoxy resin was screen printed to provide the first and the second insulating layer portions 76 and 77. The first and the second conductive layers 78 and 79 were formed by evaporation. It was very readily feasible to form the first and the second external electrodes 33 and 34 in stable contact with the pertinent ones of the internal electrodes 32.
FIG. 23 is an electrostrictive element according to an eighth embodiment of this invention. First and second layer portions 81 and 82 of an opto-setting resinous material, such as a photoresist material, are substituted for the first and the second insulating layer portions 76 and 77, respectively. The resinous material is photosensitive. Some of such materials become insoluble in a solvent at portions irradiated with rays. Others of the materials become insoluble in a solvent at other portions.
As Example X, electrostrictive elements were manufactured like the elements of Example IX. After the sintering process, a resinous material which becomes insoluble at the portions exposed to ultravilot rays was applied onto the peripheral surface in two stripes along a first and a second area of each element. A mask was formed on each stripe. On the first area, the mask was formed to cover the stripe at portions at which the peripheral ends of alternate ones of the internal electrodes 32 (FIG. 23) were exposed on the peripheral surface. On the second area, the mask was formed to cover the stripe at portions at which the peripheral ends of other internal electrodes are exposed. Uncovered portions of the stripes were irradiated by ultraviolet rays. Those portions of the stripes which were under the masks and not irradiated by the ultraviolet rays, were removed together with the overlying masks by a solvent. The remaining portions of the stripes were cured at a temperature of about 900.degree. C. to become the layer portions 81 and 82. A metal layer was evaporated towards each of the first and the second areas to provide the conductive layers 78 and 79. It was very easy to insure stable connection of the first and the second external electrodes 33 and 34 to the pertinent ones of the internal electrodes 32.
Turning further to FIG. 24, an electrostrictive element according to a ninth embodiment of this invention is similar in structure to those illustrated with reference to FIGS. 22 and 23. Instead of the insulating layer portions 76 and 77 or 81 and 82, first metal layer portions 83 are formed on the first area 46 in contact with the respective peripheral ends of alternate ones of the internal electrodes 32. On the second area 47, second metal layer portions 84 are formed in contact with the respective peripheral ends of other internal electrodes. As described in connection with FIGS. 3 and 4, first and second lead wires 86 and 87 are soldered or otherwise connected to the metal layer portions 83 and 84 on the first and the second areas 46 and 47, respectively. It is now understood that the first external electrode 33 comprises the first metal layer portions 83 and the first lead wire 86 and the second external electrode 34, the second metal layer portions 84 and the second lead wire 87. It is possible to raise the efficiency of production when the lead wires 86 and 87 are connected to the metal layer portions 83 and 84 either by thermocompression bonding or ultrasonic bonding, both known in the art of manufacturing IC's.
As Example XI, electrostrictive elements were manufactured like the elements of Example IX. After the sintering process, the first and the second metal layer portions 83 and 84 (FIG. 24) were formed by firing silver paste. Evaporation of aluminium or gold was equally well effective in manufacturing the metal layer portions 83 and 84.
Referring back to FIGS. 3 and 4, an electrostrictive element according to a tenth embodiment of this invention is similar in structure to that illustrated. Each internal electrode 32 is, however, made of an electroconductive material which consists essentially of a metal, such as platinum or palladium, and up to 60% by weight of the electrostrictive material of which the electrostrictive sections 31 are made.
It was already known in the art of manufacturing stacked chip capacitors that electrodes made of a metal do not tenaciously adhere to ceramic pieces among which the electrodes are interposed and that the strength of adhesion between each ceramic piece and the electrodes is improved when powder of the ceramic material is included in the electrodes so as to make the electrodes have nearly the same coefficient of thermal expansion as the ceramic piece. Although similar in structure, it has not yet been confirmed as regards multilayer electrostrictive elements whether or not inclusion of an electrostrictive material in the internal electrodes would improve the strength of adhesion between the electrostrictive sections and the internal electrodes because each multilayer electrostrictive element used either in a printer head or in a relay, is subjected to an appreciably great amount of elongation a great number of times in the direction of stack of the electrostrictive sections and the internal electrodes. As will presently become clear, it has now been confirmed that an electrostrictive element of the type being illustrated is excellent as regards the strength of adhesion.
As Example XII, electrostrictive elements were manufactured as described in connection with the elements of Example I. The platinum paste was, however, applied onto the green sheet pieces with the presintered powder added thereto in various proportions. The mixture of the platinum paste and the presintered powder was successfully sintered into the material of the internal electrodes during the sintering process.
Referring to FIG. 25, the life was tested by the use of a pulse sequence which is similar to the sequence described in conjunction with FIG. 5 except that the amplitude of the sinusoidal wave was 400 volts rather than 250 volts. The curve shows the relationship between the life and the percentage by weight of the electrostrictive material. As in FIG. 5, the life was measured by the number of pulses which gave rise to cracks or other mechanical damage in the electrostrictive elements.
Turning to FIG. 26, the maximum displacement was measured for the elements of Example XII. The curve shows the relationship between the maximum displacement and the percentage by weight of the electrostrictive material.
As seen from FIGS. 25 and 26, an increase in the content of the electrostrictive material is effective in lengthening life. Despite the relatively high voltage of 400 volts, the life exceeded one hundred million pulses when the content was in excess of 20% by weight. The content beyond 30% by weight, however, tended to decrease the maximum displacement. When the content was 60% by weight, the maximum displacement decreased to about a half. It is believed that this results from a decrease in an effective area of each internal electrode. Summarizing, the content should be 60% by weight or less and should most preferably be selected between 20% and 30%. It is to be noted that a zero content of the electrostrictive material corresponds to the electrostrictive element of the type illustrated with reference to FIGS. 3 and 4.
Returning to FIGS. 3 and 4, an electrostrictive element according to an eleventh embodiment of this invention has the same structure. Each internal electrode 32 is, however, made of an electroconductive material which consists essentially of a metal, such as platinum or palladium, and an additional electrostrictive material which can be sintered at a temperature lower than the electrostrictive material of the electrostrictive sections 31. It is believed that the additional electrostrictive material is better than the material of the electrostrictive sections 31 because the additional electrostrictive material is at least partly turned into liquid phase during the sintering process.
As Example XIII, electrostrictive elements were manufactured as described in conjunction with the elements of Example I, except for the following. Green sheet pieces were manufactured by the use of the first presintered power consisting essentially of lead magnesium niobate and lead titanate in a mol ratio of 65 to 35. The presintering was carried out at 850.degree. C. for two hours. Second presintered powder was prepared, which consisted essentially of lead magnesium niobate and lead titanate in a mol ratio of 9 to 1 as described in connection with Examples I through XII. An electroconductive material was prepared by adding the second presintered powder to platinum paste in various proportions. Sintering of stacks of the predetermined dimensions was carried out at 1280.degree. C. for one hour.
As Reference II, electrostrictive elements were manufactured like the elements of Example XII. The first presintered powder was used only for the electrostrictive sections. Sintering was carried out at 1280.degree. C. for one hour as in Example XIII. It is to be noted that the elements of Reference II as herein called, are electrostrictive elements according to an aspect of this invention and are not conventional electrostrictive elements.
In FIG. 27, the life was tested as described with reference to FIG. 25. An upper curve 88 shows the life of the elements of Example XIII for various contents of an electrostrictive material into which the second presintered powder was sintered in the internal electrodes. A lower curve 89 likewise shows the life for the elements of Reference II. It was confirmed that the content of an electrostrictive material of a lower sintering temperature should preferably be selected between 0 and 40% by weight, because a higher content tended to reduce the maximum displacement. It was furthermore found that the particle size of the presintered powder should preferably be up to 1 or 2 microns.
Referring to FIGS. 3 and 4 once again, an electrostrictive element according to a twelfth embodiment of this invention is similar in structure. Instead of a single metal or an alloy, each internal electrode 32 is made of an electroconductive material which consists essentially of platinum or palladium and up to 10% by weight of glass.
As Example XIV, electrostrictive elements were manufactured like those of Example XII. Zero to 20% by weight of soda glass was used instead of the presintered powder on coating the green sheet pieces.
Turning to FIG. 28, the life was tested as described in conjunction with FIG. 25 for the elements of Example XIV. When the internal electrodes did not include glass like the elements of Example I, the life for the pulses of the amplitude of 400 volts was of the order of two million pulses. It is clear that the life was astonishingly lengthened when the content of glass was 2% by weight or more.
Finally referring to FIG. 29, the maximum displacement was measured as described in connection with FIG. 26. When the content of glass was 8% by weight, the maximum displacement showed a tendency of gradual decrease. When the content was 10% by weight, the maximum displacement decearesed to about a half.
While this invention has thus far been described with reference to the accompanying drawing, it will now readily be possible for one skilled in the art to carry this invention into effect in various other manners. For instance, the external electrodes 33 and 34 or the conductor rods 64 and 65 may not necessarily be parallel to the stack axis but may have a helical or the like form. Addition of the electrostrictive material or glass to the internal electrodes 32 is equally well applicable with excellent results to the electrostrictive elements illustrated with reference to FIGS. 7 and 9 and others. Use of the insulating layer portions 76 and 77 or 81 and 82 or of the metal layer portions 83 and 84, is preferable for easy and stable connection of the external electrodes 33 and 34 with the internal electrodes 32 also when the peripheral ends of the respective internal electrodes 32 are entirely situated on the peripheral surface of the stack, as described in conjunction with FIG. 11 or FIGS. 16 and 17.
1. A multilayer electrostrictive element for dimensionally changing in a first direction in response to electrical pulses and for withstanding repeated application of said pulses, said element comprising:
a stack formed by a plurality of electrostrictive sections of an electrostrictive material and a plurality of internal electrodes sandwiched between said electrostrictive sections, said stack having a peripheral surface defining a cross-sectional area of said stack, each of said internal electrodes having peripheral ends on said peripheral surface and each of said internal electrodes having an internal electrode area which is substantially equal to a cross-sectional area of said stack;
first means for electrically connecting alternate ones of said internal electrodes together without connecting others of said internal electrodes, said first means including first insulating layer portions on a first area of said peripheral surface for covering respective peripheral ends of said others of said internal electrodes while leaving portions of said first area uncovered, each said first insulating layer portion covering the peripheral end of a respective internal electrode while extending in said first direction substantially less than the entire distance between said respective first electrode and either adjacent first electrode to leave uncovered substantial portions of the surfaces of said electrostrictive sections in said first area of said peripheral surface, and a first conductive layer continuously formed on both said first insulating layer portions and on said uncovered portions of said first area; and
second means for electrically connecting said others of said internal electrodes together, said second means including second insulating layer portions on a second area of said peripheral surface for covering respective peripheral ends of said alternate ones of said internal electrodes while leaving portions of said second area uncovered, and a second conductive layer continuously formed on both said second insulating layer portions and on said uncovered portions of said second area.
2. An electrostrictive element as claimed in claim 1, wherein each internal electrode is made of an electroconductive material consisting essentially of a metal and an additional electrostrictive material of a sintering temperature which is lower than a temperature of sintering the electrostrictive material of said electrostrictive sections.
3. An electrostrictive element as claimed in claim 2, wherein said electroconductive material includes up to 40% by weight of said additional electrostrictive material.
4. An electrostrictive element as claimed in claim 1, wherein said first and second insulating layer portions comprise a photosensitive resin.
2487165 November 1949 Miller
2894317 July 1959 Marks
3179826 April 1965 Trott et al.
3349259 October 1967 Kistler
3390287 June 1968 Sonderegger
3521090 July 1970 Angeloff
3586889 June 1971 Kolter
3593068 July 1971 Rosler
3686518 August 1972 Hartmann et al.
3982144 September 21, 1976 Rogers et al.
Filed: May 11, 1983
Date of Patent: Jun 11, 1985
Assignee: NEC Corporation (Tokyo)
Inventors: Sadayuki Takahashi (Tokyo), Masatomo Yonezawa (Tokyo), Atsushi Ochi (Tokyo), Takeshi Yano (Tokyo), Takeshige Hamatsuki (Tokyo), Izumu Fukui (Tokyo)
Primary Examiner: Peter S. Wong
Assistant Examiner: D. L. Rebsch
Law Firm: Sughrue, Mion, Zinn, Macpeak, and Seas
Application Number: 6/493,583
Current U.S. Class: Acoustic Wave Type Generator Or Receiver (310/334); Force Or Pressure Measuring Type (310/338)
International Classification: H01L 4118;


text:
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MG&G/SGT
Plate Tectonics Symposium
Marie Tharp Celebration
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EI LIVE K12 Is Back for Spring 2021
By Cassie Xu
We are excited to announce the return of our popular EI LIVE K12 series, which will continue to provide educational content for K12 students, educators, and parents for the rest of the 2020-2021 academic year. The series will feature experts from across the Earth Institute in 45-minute live sessions where they will share aspects of their work through lectures and interactive activities.
The series will occur once a week beginning on January 14 until June 24 at 4:00pm ET, with a few exceptions, which are noted with an asterisk. All sessions are free but pre-registration is REQUIRED for each event. RSVP links, along with the schedule from January to June, are below. We will send a Zoom Webinar link to all registered participants prior to the start of the programming. All sessions will be recorded and hosted on the EI LIVE K12 page for easy accessibility.
Parents/Students: Each session has a specific age range, so please make a note of that.
Educators: We suggest tuning in for the sessions that correspond with the age groups that you teach, and where we are able to, we will share additional readings and resources.
Communicating Climate Change
Thursday, January 14, 3:00 – 3:45pm ET*
Presenter: Dale Willman, Associate Director, Resilience Media Project
Target audience: Grades 7-12
It's hard enough getting people to listen when we talk about something simple, so how do we get them to listen when the fate of the world is at stake? Climate change threatens our very existence on the planet, but there are things we can do today that can make a real difference. You will learn about some of the tools available for communication, and how you can use them to bring about real change.
Climate Data — The Numbers Behind the Numbers
Thursday, January 21, 4:00 – 4:45pm ET
Presenter: Dara Mendeloff, Senior Geographic Information Specialist, Center for International Earth Science Information Network
Data science is growing up fast. Learn about the data science tools used in climate research by our scientists to understand geographic data, perform spatial analysis, and visualize data while communicating a story.
Antarctica Wildlife – Built for the Cold
Presenter: Margie Turrin, Director of Educational Field Programs; Laurel Zaima, Education and Outreach Coordinator, Lamont-Doherty Earth Observatory
Target audience: Grades 3-5
What adaptations does a species need to survive in Antarctica? Students will learn how species use special teeth, interlocking feathers, projectile vomiting and very deep dives to protect themselves in this wild and unique environment. Students can create their own Antarctic glacier scene in advance and add additional species from this session.
Constructing Climate-Conscious Cities
Thursday, February 4, 4:00 – 4:45pm ET
Presenter: Dannie Dinh, Program Officer and Deputy Country Lead for the Adapting Agriculture to Climate Today, for Tomorrow (ACToday) project, International Research Institute for Climate and Society
Our climate is indeed changing, ultimately altering our world as we know it. Join this creative session to learn about the risks and challenges of climate change and what innovative ideas and solutions can help reduce or adapt to those impacts. Then brainstorm and draw what these ideas would look like in our own daily life and community. Together, we will imagine and sketch our future world in the face of a changing climate.
You Spin Me Right Round
Thursday, February 11, 4:00 – 4:45pm ET
Presenter: Spencer Hill, Postdoctoral Research Scientist, Lamont-Doherty Earth Observatory
Why do storms and ocean currents always seem to be spinning around or looping? How does Earth's rotation (once every 24 hours) influence this? What about on other planets like Jupiter? In this session, we'll use a rotating tank of water and some food coloring to create real-world models that bring these big, far-off swirling systems to your own desk or table.
Under the Sea — Corals and Climate Change
Presenter: Brad Linsley, Lamont Research Professor, Lamont-Doherty Earth Observatory
This session will explore how coral skeletons can be used to generate seasonal (winter, spring, summer, fall) reconstructions of water temperature, rainfall and salinity (salt content) extending back hundreds of years. The longest coral sample scientists at Lamont have collected extends back to 1521 C.E! Students will get a close-up view of actual coral core samples that have been collected and will learn how they are sampled and analyzed in the lab to make these unique climate records.
Every Breath We Take
Presenter: Garima Raheja, PhD Candidate, Department of Earth and Environmental Sciences
Air quality and greenhouse gasses impact our health and our planet. We will learn about different pollutants in our air, and use data science to find out where they come from, where they go, and what happens along the way.
A History in Mud
Thursday, March 4, 4:00 – 4:45pm ET
Presenter: Nichole Anest, Curator, Core Repository, Lamont-Doherty Earth Observatory
The Lamont-Doherty Core Repository is home to one of the world's largest collections of ocean floor samples called sediment cores. Why are 20,000 cores not enough? Join the curator, Nichole Anest, for a look inside this unique library and a hands on activity where we will explore what is in all that mud!
The Earth's Blanket — Physics of Glaciers
Thursday, March 11, 4:00 – 4:45pm ET
Presenter: Jonny Kingslake, Assistant Professor, Department of Earth and Environmental Sciences
Target audience: Grades 11-12
Glaciers are large volumes of ice that accumulate in the world's coldest regions. They are so large that they flow under their own weight like a fluid, affect global sea levels, and act like a thick insulating blanket on the Earth's surface. This session will discuss how scientists use mathematics and physics to understand these processes and many others. We will introduce glaciers and how they work, then show you some simple equations that will help us understand how ice insulates the Earth's surface. This session is more advanced. Some familiarity with glaciers, as well as with heat flow, algebra, and other high school physics concepts, will be useful but not required.
What's Going to Happen to My Neighborhood?
Climate change impacts us all, but not all in the same way. Students will dig into the 'National Climate Assessment Report' and the 'US Climate Resiliency Toolkit' to explore data uncovering local impacts from global climate change and discuss opportunities for building a more resilient future.
How Global Climate Policy Works
Presenter: Lisa Dale, Lecturer in Discipline, Undergraduate Major in Sustainable Development, Earth Institute
Join us for this session as we explore climate change policy. With the U.S. expected to rejoin the Paris Agreement this year under a new administration, what will that mean for climate change policy in our country and globally? How do the climate policies around the world protect our planet and help us take action?
Thursday, April 1: No Session
Data Storytelling
Thursday, April 8, 4:00 – 4:45pm ET
Presenter: Jackie Ratner, Senior Project Manager, National Center for Disaster Preparedness
Learn about the stages of creating a data story, how to source data, clean it, choose a visual or other format for your story, and how to tell a story effectively using data. The session will include a brief introduction into design fundamentals for data visualization.
Talking About the Weather — Crowdsourcing and Memories of Climate
Thursday, April 15, 4:00 – 4:45pm ET
Presenters: Max Mauerman, Staff Associate, and J. Nicolas Hernandez-Aguilera, Postdoctoral Research Scientist, International Research Institute for Climate and Society
Despite advances in measuring historical climate conditions with satellites and weather stations, scientific instruments do not always reflect what is happening on the ground. This is why it is important to verify sensor data with the communities who are directly affected by droughts, excess rain, and other hazards, in order to improve climate risk management. To address these issues, we present a mobile game, iKON, to gather accurate historical climate data from communities around the world. iKON uses behavioral science principles to elicit better responses, such as priming memory and incentivizing accuracy through a points-reward matching system. We will explain the importance of crowdsourcing for climate risk management and have fun playing our game during this session.
What We Talk About When We Talk About Climate
Monday, April 19, 4:00 – 4:45pm ET*
Presenter: Josh DeVincenzo, Senior Instructional Designer, National Center for Disaster Preparedness
How do people think about climate change? What can we do to engage more people in the conversation or become better climate learners ourselves? Exciting research spanning psychology, communications, and education are looking into these very questions. During this session, students will be introduced to thinking about climate change as a system, the psychology of climate change as well as strategies to engage their communities in discussion and education about the impacts of climate change.
Tropical Tales of Polar Ice
Presenter: Jacky Austermann, Assistant Professor, Department of Earth and Environmental Sciences
Each rock tells a story. In this session, we will go on a virtual journey to the Bahamas and learn about what rocks and fossils on these Caribbean islands can tell us about past and future sea level change.
Lights, Camera, Robots: Exploring the Earth's Final Frontiers
Thursday, May 6, 4:00 – 4:45pm ET
Presenter: Vicki Ferrini, Research Scientist, Lamont-Doherty Earth Observatory
Very little of the world's ocean has been mapped or explored – it is Earth's final frontier. Learn about how scientists and engineers explore, visualize, and study hard to reach underwater environments in an effort to unlock the mysteries of the deep.
A World of Change: Ice and Ocean Interactions in Antarctica
Thursday, May 13, 4:00 – 4:45pm ET
Presenter: Frank Nitsche, Research Scientist, Lamont-Doherty Earth Observatory
There are reports in the news that the Antarctic Ice Sheet is melting. But why and how is it melting? In this session, we will learn about interaction of ice and ocean water around Antarctica, the main driver of melting today. We will talk about how and where warm ocean water is getting to the ice and melting it, how we observe and measure ocean water and how it is making it to the ice.
Make 'n Break Ice
Presenter: Christine McCarthy, Lamont Associate Research Professor, Lamont-Doherty Earth Observatory
Did you know that ice can be found throughout the solar system? In my lab we make ice samples like those found on Earth and other moons and planets. We also use machines to squish, break, slide and even 'tickle' samples to recreate all the forces that they may experience on different worlds, and then we record how they respond. We will talk about some of my favorite icy moons and see all the cool tools we use in the lab.
Rock You Like a Hurricane
Presenter: Chia-Ying Lee, Lamont Assistant Research Professor, Lamont-Doherty Earth Observatory
Join us for a session about hurricanes and what's happening to them in an age of climate change. Learners will get a basic understanding of how hurricanes form, develop, grow, and change, as well as what scientists know (and don't know) about the 2021 hurricane season.
There Goes that Boom Boom Pow!
Thursday, June 3, 4:00 – 4:45pm ET
Presenter: Nicholas Frearson, Senior Staff Associate, Lamont-Doherty Earth Observatory
Volcanic eruptions are one of the most powerful natural phenomena that we can witness today. When Vesuvius erupted, it sent superheated clouds of ash and molten rock over 20 miles up into the atmosphere. Today, it is still a challenge when volcanoes close to human habitation erupt without warning, as was evidenced by the eruption of Taal Volcano in the Philippines in January 2020. So to try and solve this problem, scientists are developing an early warning system to predict volcanic eruptions. They are doing so by installing arrays of state-of-the-art sensors on Cleveland, an active volcano in the Aleutian Islands, and beaming live data back from it to our labs in New York. Join us for this session to learn how scientists are analyzing volcanic data in real time to identify patterns that will help them anticipate future eruptions.
The Ice That Made Manhattan
Thursday, June 10, 4:00 – 4:45pm ET
Presenter: Michael Kaplan, Lamont Research Professor, Lamont-Doherty Earth Observatory
Target audiences: Grades 6-12
During the last Ice Age, a large ice sheet covered much of New York City. During this session, students will learn the clues that we look for to know that the New York City region was covered by an ice sheet, or the evidence that was left behind across the surrounding area.
Grow Your Green Thumb
Presenter: Alex Root, Postdoctoral Research Scientist, Lamont-Doherty Earth Observatory
In this workshop participants are invited to bring two plants or cut flowers for an observation, sketching, and journaling session. We will share and discuss the beautiful forms and functions of plants. The workshop will conclude with activities to grow plants at home from vegetables, tips for going green, and the importance of plants in our lives.
Marie DeNoia Aronsohn
marieda@ldeo.columbia.edu
CIESIN
EI Live
International Research Institute for Climate and Society
national center for disaster preparedness

redpajama_set_name: RedPajamaCommonCrawl


text:
layout: post-classes
title:  "Project 1 Review Session"
date:   2016-10-05 13:00:00 +0900
author: Seongjin Lee
categories: project1 announcement
comments: true
---

If you had difficulties understanding what we did in the class, please visit _Fusion Tech Center #804_ any time on this Friday (2016-10-07). Class assistant will help you understanding kernel compile, module compile, making the file system, and using ctags.

If you don't have time to review session, then please send a mail (nyg0813_at_gmail_dot_com) explaining where you got stuck.

redpajama_set_name: RedPajamaGithub


Welcome to The Manor! Our school warmly welcomes boys and girls aged 2-11. With purpose-built designated spaces for Music, Art, DT, Drama, French, Science and Food Technology, as well as light and airy, spacious classrooms and a brand new Sports Hall which sits alongside tennis and netball courts and playing fields, it really is a fantastic environment for children to thrive and excel. Please come along and see for yourself – we look forward to meeting you.
Please join us at one of our open events. Our older pupils would be delighted to give you a tour of the School. There is no need to book, please just come along on the day. If you need any further information, please contact our Director of Admissions and Communications, Mrs Karen Copson on the details below.
It is always possible to visit the School on a normal school day, please contact Mrs Karen Copson to arrange an appointment, a tour of the school and a meeting with the Headmaster, Alastair Thomas.


Warning: This driver has not been extensively tested, and only works in the 3rd ed.
I added a function to devpcmcia.c based on pcmspecial() from the pc kernel, The point of this function is to fetch the version string from the card, as this is used by the ec2t driver to support different kinds of ec2t cards. This has only been tested w/ the Linksys PCM100 v2 card and the single slot PCMCIA adapter for the bitsy.
ether8390.c (just the pc kernel one).


Even though precise source of neuroma stays cloudy, you can find a lot of facets which may result in neuroma development. Find more information regarding it particular condition.
Neuroma or Morton's neuroma is often discovered between your feet, many often the fourth and third feet. Even the absolute most frequent signs or symptoms are burning feeling in direction of your feet, stinging feeling pain underneath the ball of their foot.
Foot issues like flat feet or high heeled feet often leads towards the creation of neuroma. In horizontal feet, the bottoms of their feet enter in contact with the bottom. The reduced arches induces greater tension to be exerted onto the fore-foot, resulting in compression and irritation of these nerves. In high-arches, the insteps of the feet have been increased more than ordinary, and also can induce irritation of nerves. Aside from foot health conditions that might raise the potential of establishing neuroma are bunions, hammer feet, and positioned feet.
Donning the incorrect kinds of foot wear may create neuroma soreness even worse. Shoes which are too restricted, pointed out shoes, shoes and highheels specially shoes within two in.. These sorts of socks may compress the feet and produce the pain even worse neuroma.
Being incredibly busy in sport may also worsen the signs of neuroma. Specifically, sports activities which demand conducting may irritate the illness as this could put additional stress on the nerves at your foot. After the burden of this human body has been put on the surfaces of the foot, then this may result in the bones to pinch nerves. Any sport or physical exercise which absorbs persistent strain within the forefoot can aggravate neuroma.
Preceding foot harms or some different sort of foot injury may likewise function as the source of neuroma. This may possibly be by blunt injury towards the fore-foot or an immediate harm to the guts. With the years, the compression could cause greater harm to the guts.
Throughout early phases of neuroma, traditional remedies tend to be profitable. Wearing good apparel, averting tasks which may aggravate the status and also immobilization might be valuable. Physical treatment may likewise be useful at early phases.
Other options are customized orthotics, corticosteroid shots, alcoholic beverages sclerosing shots, as well as cryotherapy. Surgicla methods like nerve de compression and nerve wracking excision will also be some times achieved. But, operation is frequently the previous hotel as this includes any risks related to surgical procedures like swelling, and swelling and recurrence of the status, bleeding issues, delayed recovery, as well as even infection.
50 percentage of individuals that undergo operation due to neuroma repent that it, irrespective of that which the doctor is. Anxiety might be more difficult compared to authentic neuroma! In the event you believe you may be afflicted by Morton's neuroma, find help from the health care provider or physician that focuses on foot issues to know about non surgical remedies for neuroma.
Lorrine Yen has got several decades of knowledge being a health care research and also a expert wellness insurance and health author. She results in good excellent articles and also concentrates in drug and health.


The Valtifest festival last summer was one event not to be missed. Not only does the festival has been a success, but the Valtifest app is also received very positive by users. For example, research has shown that of all people on Valtifest who have downloaded the app, 85% has actually used it. In addition, the Valtifest app also scores well in terms of functionality. A convincing rate of 88% (men) and 97% (women) find the app functional. These figures clearly show that the Valtifest 2012 app is rated excellent by users!
DTT blog: Valtifest app rated excellent!
DTT blog: Valtifest 2012 in the Appstore!


It is difficult to build a house, but it's easy to destroy it in a twinkle of an eye. In Nigeria, and indeed the world over, bad news sells like hot cake. The religious controversies that surrounded the Synagogue Church Of All Nations (SCOAN) revered General Overseer, Prophet T.B Joshua over the years could be traced to some dubious, iniquitous and callous propagandists who never wanted the gospel of Christ to be heard. There have been several baseless vituperations and invectives from different respected ministers of God and disgruntled disciples attacking the personality of Prophet T.B Joshua.


text:
Search Results for 'Zambia'
An Spidéal students to give Zambian young people a helping hand
Eighteen transition year students from Cólaiste Chroí Mhúire in An Spidéal along with volunteer leaders, will be going to Zambia to work with the Alan Kerins Project.
Minister launches three-way development partnership for youth in Africa at NUI Galway
Galway Advertiser / NewsThu, Jun 24, 2010
On Monday the Minister of State with special responsibility for Overseas Development Peter Power TD launched a new three-way partnership at NUI Galway, which it is hoped will greatly benefit young people in Zambia.
Zambian teenagers helped by Alan Kerins Projects visit Galway
Galway Advertiser / NewsThu, May 20, 2010
Four Zambian students, who have been helped by Alan Kerins Projects paid a visit to Galway recently and attended a special evening of friendship hosted by the voluntary organisation on Friday last in the Clybaun Hotel.
Learning while helping others
A series of seminars which hopes to raise money to help the poor, and educate the people of Galway, has been organised by Seán Connaughton, a part time lecturer at GMIT. Motivated by the success of former students who referenced their experience and motivation to their time at GMIT, Connaughton, has Trio Seminars, a training experience which he hopes will benfit the wider community.
Under the African skies
Elaine Divilly spent two months working in Zambia project managing a block production and building development as part of the Alan Kerins African Projects. In the process, she learned a lot about the realities of Africa and herself too.
NUIG leads UNESCO study in Zambia
The UNESCO Child, Youth and Civic Engagement team, based in NUIG, is to take part in an international collaborative research project on civic engagement, youth, and gender in Zambia.


"The whole world is talking about Netanyahu, Trump and Bin Salman's isolation, not Iran's," Zarif claimed.
Iran is not isolated and Europe stands by it, he added.
He made his remarks after the European Union (EU) announced that new measures are ready to take effect in order to protect European businesses from the impact of US sanctions on Iran, which will partially take effect on Monday. They target Iran's automotive sector as well as gold and other metals.
The measures are aimed at saving an agreement that is supposed to curb Iran's nuclear ambitions after the US abandoned the pact in May. The EU says the pact is important for global security and that it is trying to keep economic and financial supply lines to Tehran open.
The EU's Executive Commission said Monday that the so-called "blocking statute" will take effect beginning at midnight.
The mechanism stops European companies from complying with the US sanctions unless they have authorization from the Commission.
It also blocks the effects of US court actions in Europe and allows European firms to recover damages arising from the sanctions from anyone who causes them.
He pointed to "the state which arrests another state's prime minister," namely Saudi Arabia; "the president who violates international agreements such as NAFTA and Paris," in reference to Trump; and "the one who has repeatedly abused the rights of Palestinians," Israel.
"The US is waging the propaganda that it is in touch with Iran's people and Netanyahu writes tweets and sheds crocodile tears every day. You claim that you have connection with Iranian people but the first sanction that you reimposed against Iran was related to airplane sales, airplanes that would have been used in favor of Iranian people," Zarif charged, according to ISNA news agency.
European foreign ministers said they "deeply regret" the reimposition of US sanctions on Iran.
A statement Monday by EU foreign policy chief Federica Mogherini and the foreign ministers of France, Germany and the UK insisted that the 2015 Iran nuclear deal "is working and delivering on its goal" of limiting Iran's nuclear program.


I see the following in TenantConfig. What is ACE and what does each of the following mean?
ACE (Analytics Container Engine) is THE core way to execute data dependent calculation (think executing machine learning models) in the c3 platform. Check the types DFE, Analytic, and Metric to learn more.


Gabriel's Journey is the third book in the Racing to Freedom Trilogy by Alison Hart. Also included in the trilogy is Gabriel's Horses (book one) and Gabriel's Triumph (book two). Together, the trilogy explores the complexity of African American History and the Civil War with a stirring character and his love of horses.
When thirteen-year-old Garbriel leaves the home of his former master to join his father in the Union Army, he finds he is too young to be a soldier. His experience caring for horses and as a jockey lands him the job of mucking stables and taking care of the Fifth U.S. Colored Calvary's horses instead. When he tames the spirited horse, Champion, he gains the respect of it's owner, the white commander, Captain Waite.
Gabriel's success taming Champion, earns him a uniform, his own horse and a chance to join the ranks of soldiers on their way to battle. He leaves with hope and desires freedom, but learns those words come with a price. Being a soldier is harder than Gabriel expected and his hope turns to discouragement when he encounters bad weather, low supplies and racism from both the Union and Confederate soldiers.
When Gabriel's father and Captain Waite do not return from the battle of Saltville, Gabriel rides into the battlefield in search of them, putting aside his own fears and gaining courage along the way.
Alison Hart's poignant end to the Racing to Freedom Trilogy provides a raw look into the African American contributions to the Civil War and the racism they encountered. The first person narrative through the eyes of a thirteen year old soldier, Gabriel, really drives the message of the atrocities of war and the love of family freedom and horses. For those looking for a great piece of historical fiction, I recommend the Racing to Freedom Trilogy. It is well researched and well written.
Check back for your chance to win a hardback signed copy of Gabriel's Journey.


This five-level reading series is organized by themes from academic disciplines.
• Authentic readings from a variety of sources engage students' interest.
• Step-by-step approach helps students develop academic knowledge, vocabulary, and reading strategies and skills.
• The aim of the series is to make students more effective and confident readers by providing high-interest readings on academic subjects and teaching them skills and strategies for effective reading, vocabulary building, note-taking and critical thinking.
• The series encourages students to discuss and write about the ideas they discovered in the readings, making them better speakers and writers of English as well.
Five-level, highly "teachable" writing series, with an approach that balances process with structure, for development of writing skills from sentences to research papers.


Opening daily from 11am to 4pm Monday 22 October to Sunday 28 October, our 2018 linen journey through Scotland concludes with a week of exhibition and events at The Highland Folk Museum in Newtonmore.
Working with the wonderful curatorial team at this ethnographic open air museum, unique in Scotland and with colleagues from the University of the Highlands and Islands, we supplement our core exhibition of contemporary design from Scotland, Ireland and the Netherlands with events reaching out into Highland communities with a past and present focus on flax fibre and linen cloth.
Our full events schedule is noted below with events at Leanach Church and nearby withn the Folk Museum grounds. We look forward to welcoming you: all events are free and open to all.
A' fosgladh gach latha bho 11m gu 4f, Diluain 22 Dàmhair gu Didòmhnaich 28 Dàmhair, tha cuairt Ar Sgeulachd Anairt 2018 tro Alba a' crìochnachadh le seachdain de thaisbeanadh is de thachartasan aig Taigh-tasgaidh Sluagh na Gàidhealtachd ann am Baile Ùr an t-Slèibh. Ag obrachadh leis an t-sàr sgioba tasgaidh aig an taigh-tasgaidh eitneografaig seo air a' bhlàr a-muigh, agus le co-obraichean bho Oilthigh na Gàidhealtachd agus nan Eilean, tha sinn a' cur ri ar prìomh thaisbeanadh de dhealbhadh co-aimsireil à Alba, Èirinn agus an Òlaind. Bidh na tachartasan a' ruigsinn a-mach gu coimhearsnachdan na Gàidhealtachd agus a' toirt sùil air snàithleach lìn agus aodach anairt san latha a dh'fhalbh agus san latha a th' ann. Thèid clàr-ama iomlan nan tachartasan againn fhoillseachadh sna làithean air thoiseach agus tha sinn a' dèanamh fiughair ri fàilte a chur oirbh. Tha an taisbeanadh agus na tachartasan an-asgaidh agus fosgailte do na h-uile.
'Our Linen Stories' Curator John Ennis is originally from N.Ireland and has been resident in Scotland since 1985. Stepping aside from a career in medicine in 2012 to pursue a passion for design, this is John's first exhibition tour and in these informal talks, he offers a guide to the Highland Exhibition and reflects on his experiences producing the exhibitions and events that have formed Our Linen Stories to date.
On Tuesday 23 and Wednesday 24 October, Maureen Hammond and colleagues from the University of the Highlands and Islands Centre for History offer us a demonstration of flax was prepared back in eighteenth century Badenoch.
'As a volunteer gardener near Duddingston Loch in Edinburgh I was intrigued to find that Duddingston had been a weaving village which in times past produced a rough cloth known as Duddingston Hardings. I was curious to find out more about this fabric and discovered that it was linen made from local flax which was retted in the loch, before being spun into a utility fabric. Given its lowly status, no samples of this cloth have survived to the present day. I was inspired by the story of this forgotten cloth and resolved to make some simple drafts of plain weaving where the fibres are highlighted as opposed to the structure of the cloth. I harvested plants from the Loch and used these fibres to make thread to weave my own cloth. In building my fabric, I counted the 'picks' as the weft passed back and forth while the repetition of stripes made me think of time passing and a tentative link to Duddingston Loch.


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Canada's Justin Trudeau: Religious Christians "Worst Part Of Society"
May 14, 2019 by Jon Watkins
In Trudeau's Canada, Christians are Not Welcome
Bradley Martin | Christian Post – According to a new clause introduced by Canadian Prime Minister Justin Trudeau, pro-life Christians will be barred from federal funding unless they support a woman's right to an abortion. Conservative Christian applicants for the youth summer jobs program, which provides grants to not-for-profit employers in order to encourage the hiring of students, must betray their conscience in order to qualify for federal funds.
"I have met Justin Trudeau three times," said Pastor Steve Long, a Canadian Baptist minister. "Sadly my last meeting with him in his office was very disappointing. He told […] me that evangelical Christians were the worst part of Canadian society."
The truth is that Trudeau's enmity toward Christians is not solely against evangelicals. The abortion clause has been met with much concern by a growing number of faith-based communities in Canada. Father Niaz Toma, a Chaldean Catholic priest, said his community of Iraqi Christians won't be able to apply for the grant and has referred to the attestation as a persecution of his people.
"We will never compromise our faith for the sake of grants to be received from the Canadian government," said Father Toma.
The Trudeau government has exhibited a history of irreverence toward Christian beliefs, such as when Trudeau himself was photographed wearing a Christmas sweater depicting the Last Supper with party emojis. Trudeau also came to the defense of his newly appointed governor general accused of mocking religious people who believe that "divine intervention" played a role in the formation of life on Earth.
While these actions are certainly disrespectful, Canada under Trudeau has become a very unwelcome place for Christians who flee from persecution in the Middle East. When former Canadian Prime Minister Stephen Harper prioritized Christian and religious minorities for refugee status because they were targeted for extermination by ISIS, Trudeau called this policy "disgusting."
"When the genocide against Yazidis and Christians by ISIS took place, the Canadian government under Harper immediately sent Canadian forces to their rescue," said Steve Maman, affectionately known by many as "the Jewish Schindler" for rescuing over 140 Yazidi and Christian women forced into sex slavery by ISIS. "Prime Minister Harper and his Defense Minister Jason Kenney had traveled together to the Kurdish territories and pledged $140 million in assistance."
Harper also coordinated with CYCI: The Liberation of Christian and Yazidi Children of Iraq, Maman's foundation to assist Yazidis in Greece and the Kurdish territories. It was Harper who also launched Canada's Office of Religious Freedom, in order to monitor religious persecution and protect freedom of religion internationally. Shortly after taking office, Trudeau closed the agency. Trudeau also withdrew Canada's fighter jets from bombing operations against ISIS.
"Over 30,000 Syrian refugees were brought to Canada in an expedited manner and found themselves immediately taken care of by the Trudeau government," said Maman. "Despite Canada recognizing the genocide of Yazidis, the fact that the Trudeau government offered to help only 1,200 Yazidis speaks for itself. And absolutely no help was offered to the Christian victims."
If you go to the store to buy Meat, don't run to the Milk section or the Junk Food aisle looking for it!!
The Meat Section is the True Gospel of Jesus Christ.
The Milk Section is likened to those who will not preach on sin and Hell, just a feel good message, the Social gospel.
The Junk Food Isle is the outright false doctrine AKA the prosperity gospel, name it and claim it, the Hebraic Roots movement and other false teachings!!
Feasting on just Milk and Junk will eventually cause you great harm, you can count on it!!
If you appreciate what this Ministry is doing to Expose the Fake Christians, Satanists, Witches, Communist/Socialist Democrats, R.I.N.O Republicans and the assault on our Conservative, True Christian values, please consider a small donation to help us continue and expand. This Ministry is not only under attack by the Enemy, we are now under attack from supposed Christians also. It is what Tom Horn calls 'Blood on the Altar"!
Categories Abortion=Legal Murder, Biblical Ignorance, Christian Persecution, Drag Queen, False Religions, Islam, LGBTQPXYZ, Man made Religion, Political Correctness, Sexual Perversion, Transgender Tags Abortion=Legal Murder, Homosexual, Islam, War on Christianity
The Democrats Speak the Truth About Abortion – Accidentally
White Girl Rejects Getting Pregnant: She 'Doesn't Want to Create any More White People'
Rick Warren to Muslims: The God of the Bible and Allah are the Same. NOT!!


This Wednesday, the public is invited to purchase a piece of the Red Deer Arena after the facility closed in April.
Many items from the arena were repurposed, moved to other City facilities or sold to other municipalities in Central Alberta, as The City works to retire the Red Deer Arena with environment top of mind. Items that have not been repurposed, such as the bench seating, will be available for purchase Wednesday, May 11, 2016 at the Red Deer Arena (4725D 43 Street) from 5 to 9 p.m.
Large items, including ice making equipment and the score clock, will be up for auction online and details provided after the sale. Any proceeds will go towards the construction of the new downtown arena.
The Downtown Arena Project involves decommissioning the Red Deer Arena and building a new modern arena in its place. The new downtown arena, set to open in 2018, will offer welcoming gathering spaces and an indoor walking track for the community. The new facility is also being designed to meet energy and environmental standards for a greener and more efficient operation. More information about the project is online at .


Reciting Surah behind the imam..
i used to recite surah while i was praying in the jamaat behind the imam.i heard that you are not supposed to recite surah using your tongue but not loudly behind the imam.whenever i hear the imam recite...i automatically start reciting behind him silently.i just wanted to make sure if this is right or wrong.help me with the right procedure of praying in a jamaat behind the imam.
The Muqtadi (follower) Should Listen and Remain Silent.
However, if a person did recite behind the Imam, Salah will be complete.
#Allah Ta'aala says: "When the Qur'an is being recited then listen attentively and remain silent so that Rahmah will be showered upon you".
#Hazrat Abdullah Ibn Mas'ud, Abu Hurairah, Abdullah Ibn Abbas and Abdullah Ibn Mughaffal (RA) state that this verse of the Quran was revealed with regards to the Khutba (of Juma'ah) and with regards to Salaah. [Tafsir Ibn Kathir, vol. 1 pg. 281] The dictates of this verse of the Holy Qur'an is that when the Imaam recites the Qur'an aloud, the followers should listen attentively, and when he recites softly, the followers should remain silent.
#Rasulullah (Sall Allahu alaihi wa Aalihi wa Sallim) is reported to have said: "When you begin your congregational prayers, straighten your rows. Thereafter when the Imaam says the takbeer (i.e. when he says Allahu Akbar aloud) you must also say the takbeer. However, when he begins the recital of the Qur'an, you must remain silent. And when he recites walad daul leen then you should say Aameen". By performing your salaah in this manner Allah Ta'ala will love you." [Muslim; ch. on tashahhud] (A similar Hadith has been narrated by Abu Hurairah (radhiallahu anhu)-Imaam Muslim has attested to its authenticity).
-However, one must recite a surah if a person is performing salah individually-.
"Must the muqtadi recite behind the Imam?" He replied that the qiraat of the Imaam is sufficient for the muqtadi. But if he performs salaah individually, then he must recite qiraat. It was the practice of Hazrat Abdullah Ibn Umar (radhiallahu anhu) also that he would not recite surah fatiha behind the Imam. (In Aathaarus Sunan (Vol. 1 pg.89) this Hadith has been classified as sahih).
#Hazrat Jaabir (radhiallahu anhu) narrates: that the one who does not recite sura fatiha even in one rakaat, his salaah is not valid. However, if he is behind an Imam he must not recite surah fatiha. (This Hadith has been classified as hasan ? Tirmizi - ch. on not reciting behind the Imaam).


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Middle East News | Palestinians
Palestinian Shot During Gaza Border Clashes Succumbs to Wounds
Fares Arkab, 29, was shot in the abdomen during clashes on the Israel-Gaza border, according to the Palestinian Health Ministry ■ Islamic Jihad claims he was a member of their military wing
Jack Khoury
FILE PHOTO: Palestinians in the Gaza Strip evacuate a wounded man from the demonstrations near the border with Israel, March 30, 2018. Credit: MOHAMMED ABED/AFP
A 29-year-old Palestinian, who was shot in the abdomen during clashes between Israeli soldiers and protesters along the Israel-Gaza border last Friday, succumbed to his wounds on Monday, bringing the death toll to 16, the Palestinian Health Ministry reported.
To really understand Israel and the Middle East - subscribe to Haaretz
Contrary to the aforementioned report, DPA reported that Fares Arkab is the 18th Palestinian to die after the protests in the Gaza Strip.
Arkab had been protesting east of Khan Yunis, in the southern Gaza Strip.
Al-Quds Bridgades, a military wing of the Palestinian Islamic Jihad organization, also announced that Arkab was a member of the Brigades.
>> Israel beat Hamas. Now it may lose its victory | Analysis ■ Debunking Israel's talking points on deadly Gaza protests | Opinion >>
Around 30,000 Palestinians participated in last Friday's protest march near the border, which saw a number of protesters throw stones and firebombs in the direction of Israeli soldiers. The protests were held at six different points.
Gaza mass protests force Israeli military to maneuver between two contradictory goals
Gaza footage shows protester shot in the back while running away from Israeli border
15 killed, dozens wounded as thousands gather on Israel-Gaza border
Gaza border clashes resume as thousands attend funerals of 15 Palestinians killed in Friday's protests
The Palestinian Health Ministry has so far reported 16 dead, including Arkab, and over 800 wounded from live Israeli army gunfire, including 154 in the head, 52 in the chest and back and 38 in the abdomen.
Despite criticism about the number of deaths, the IDF stated yesterday that it would not be changing its policy for opening fire in Gaza. The military forces' main task is to block the protesters from infiltrating Israeli territory: "That is the price we are prepared to pay to prevent a break in," a senior source told Haaretz.
Protests continued on the Gaza border on Sunday. One protester was shot in the head and badly wounded near Khan Yunis, two were wounded in northern Gaza, and one was wounded east of the city.


The Marta Coat is a trench-inspired design that effortlessly drapes the body with its full length style. Structured at the shoulders and featuring a classic lapel, this relaxed silhouette adds definition to your ensemble with its waist belt.
The Marta Coat is crafted from a wool blend and is the perfect option to layer over your everyday ensemble.


We are going to build a global software platform that allows patients to easily and reliably capture their own Patient Generated Health Data on their own smartphone. The patients can share their data with people they know or peer-patien..
I am looking for a short catchy name for an app which will link producers deejays musicians and singers and let them exchanhe knowhow and songs. No winner yet... need something original thats catchy but a good quality name.