Aerodynamic force generation and power requirements in forward flight in a fruit fly with modeled wing motion were studied using the method of computational fluid dynamics. The Navier-Stokes equations were solved numerically. The solution provided the flow velocity and pressure fields, from which the vorticity wake structure and the unsteady aerodynamic forces and torques were obtained (the inertial torques due to the acceleration of the wing-mass were computed analytically). From the flow-structure and force information, insights were gained into the unsteady aerodynamic force generation. On the basis of the aerodynamic and inertial torques, the mechanical power was obtained, and its properties were investigated.
The unsteady force mechanisms revealed previously for hovering (i.e. delayed stall, rapid acceleration at the beginning of the strokes and fast pitching-up rotation at the end of the strokes) apply to forward flight. Even at high advance ratios, e.g. J=0.53-0.66 (J is the advance ratio), the leading edge vortex does not shed (at such advance ratios, the wing travels approximately 6.5 chord lengths during the downstroke).
At low speeds (J≈0.13), the lift (vertical force) for weight support is produced during both the down- and upstrokes (the downstroke producing approximately 80% and the upstroke producing approximately 20% of the mean lift), and the lift is contributed mainly by the wing lift; the thrust that overcomes the body drag is produced during the upstroke, and it is contributed mainly by the wing drag. At medium speeds (J≈0.27), the lift is mainly produced during the downstroke and the thrust mainly during the upstroke; both of them are contributed almost equally by the wing lift and wing drag. At high speeds (J≈0.53), the lift is mainly produced during the downstroke and is mainly contributed by the wing drag; the thrust is produced during both the down- and upstrokes, and in the downstroke, is contributed by the wing lift and in the upstroke, by the wing drag.
In forward flight, especially at medium and high flight speeds, the work done during the downstroke is significantly greater than during the upstroke. At advance ratios J≈0.13, 0.27 and 0.53, the work done during the downstroke is approximately 1.6, 2.8 and 4.2 times as much as that during the upstroke, respectively.
At J=0 (hovering), the body-mass-specific power is approximately 29 W kg-1; at J=0.13 and 0.27, the power is approximately 10% less than that of hovering; at J=0.40, the power is approximately the same as that of hovering; when J is further increased, the power increases sharply. The graph of power against flying speeds is approximately J-shaped.
From the graph of power against flying speeds, it is predicted that the insect usually flies at advance ratios between zero and 0.4, and for fast flight, it would fly at an advance ratio between 0.4 and 0.53.
It has been shown that quasi-steady analysis cannot predict the aerodynamic forces and power requirements of insects in hovering (Ellington, 1984b,c) or forward flight (Dudley and Ellington, 1990b; Willmott and Ellington, 1997b). Researchers have been working to shed light on the unsteady mechanisms of aerodynamic force generation and predict satisfactorily the power requirements in such cases.
Dickinson and Götz (1993) measured the aerodynamic forces on an aerofoil started impulsively at a high angle of attack in the Reynolds number (Re) range of a fruit fly wing and showed that lift was enhanced by the presence of a dynamic stall vortex, or leading-edge vortex (LEV). But lift enhancement was limited to only 2-3 chord lengths of travel because of the shedding of the LEV. For most insects, a wing section at a distance of 0.75R (where R is wing length) from the wing base travels approximately 5.3 chord lengths during an up- or downstroke in hovering flight (Ellington, 1984b); in forward flight, the section would travel an even larger distance during a downstroke.
Ellington et al. (1996) performed flow visualization studies on the hawkmoth Manduca sexta and a mechanical model of the hawkmoth, and discovered that on the flapping wings of the insect, the LEV did not shed during the translational phase of either up- or downstroke. Analysis of the momentum imparted to the fluid by the vortex wake showed that the LEV could explain the high lift on the insect wings. This high lift mechanism is called the delayed stall, or dynamic stall, mechanism (Ellington et al., 1996; Dickinson et al., 1999). This mechanism has been confirmed by computational fluid dynamic analysis (Liu et al., 1998). By measuring the flow field near the wings and the aerodynamic force on the wings of a mechanical model of the fruit fly Drosophila melanogaster (the Re of the fruit fly wing is 1-2 orders of magnitude smaller than that of the hawkmoth), Birch and Dickinson (2001) found that the LEV did not shed in the translational phase of either up or downstroke and that large lift was maintained in the phase, showing that the delayed stall mechanism is valid for a wide range of Re.
Dickinson et al. (1999) and Sane and Dickinson (2001) conducted force measurement studies using the mechanical model of the fruit fly and showed that in the case of advanced rotation (wing rotation preceding the stroke reversal), in addition to the large lift and drag during the translatory phase of a stroke, large lift and drag peaks also occurred at the beginning and the end of the stroke (i.e. around the stroke reversal). Dickinson et al. (1999) suggested that the force peaks at the beginning of the stroke could be explained by the wake capture mechanism [an increase in the effective fluid velocity due to vortex wake shed by the previous stroke (Dickinson, 1994)], those at the end of the stroke by the rotational circulation mechanism [the lift due to wing rotation is related to the rotational circulation by the Kutta-Jukowski equation and the rotational circulation is determined by the Kutta condition as being proportional to the product of the rotation rate and the distance between rotation-axis and 0.75 chord position (Fung, 1969)]. They provided evidence for the wake capture by flow visualizations made at the start of a stroke and by force measurements after halting the wing at the start of a stroke. Dickinson et al. (1999) and later, Sane and Dickinson (2002), assumed that the total force (lift and drag) due to the wing rotation (rotational force) could be related to the rotational circulation by the Kutta-Jukowski equation, and using measured rotational force, they determined the rotational circulation as a function of the rotation rate and the rotation-axis position. The experimentally determined rotational circulation agreed reasonably well with that predicted by Fung's theory (Fung, 1969), providing evidence that force peaks near the end of the stroke were due to rotational circulation.
Using the method of computational fluid dynamics (CFD), Sun and Tang (2002a) simulated the unsteady flow around a model fruit fly wing conducting flapping motions similar to that in the experiment of Dickinson et al. (1999). Different, but complementary, explanations for the force peaks were provided. By varying the acceleration at the beginning of a stroke, it was found that the force peaks there were closely related to the acceleration. From the computed flow field, it was observed that during the fast acceleration of the wing, strong vorticity was continuously generated on the lower wing surface and shed at the trailing edge, while strong vorticity of opposite sign was continuously generated at the upper wing surface. From vorticity dynamics theory (Wu, 1981), this would give rise to a large time rate of change of vorticity moment and thus large forces. If the velocity due to the previous strokes was directed towards the wing at the start of the stroke, wake capture mechanism would also contribute to the force peaks. But the computed results showed that the velocity was directed downward. Therefore, the authors suggested that the large force peaks at the beginning of the stroke could be explained by the rapid generation of strong vorticity due to the fast translational acceleration of the wing. However, it should be noted that the computed flow field in front of the wing at the start of a stroke is different from that visualized experimentally (Dickinson et al., 1999; the later shows the existence of wake capture effect and the former does not), and that although the computed forces are generally in agreement with the measured, there are noticeable discrepancies around the stroke reversal [see the comparisons in Sun and Tang (2002b) and in the `validation' section of the present paper]. Thus there exists the possibility that the CFD simulations could not capture accurately all features of the flow. During the fast pitching-up rotation near the end of the stroke, it was also observed that new vorticity of large strength was produced. The authors suggested that the large force peaks near the end of the stroke could be explained by the rapid generation of strong vorticity due to the fast pitching-up rotation of the wing. Note that the rotational circulation approach (Dickinson et al., 1999; Sane and Dickinson, 2002) is a special case of the vorticity dynamics theory; under conditions that the flow is quasi-steady and inviscid, the equations in the rotational circulation approach can be derived from the vorticity dynamics theory. Therefore, the above explanation for the wing rotation effects is complementary to that based on the rotational circulation approach.
As a result of the above works and numerous others (e.g. Vogel, 1966; Weis-Fogh, 1973; Ellington, 1984a,b, 1995; Ennos, 1989; Dudley and Ellington, 1990a,b; Willmott et al., 1997; Wang, 2000), we are now better able to understand how insects produce large lift.
With the current understanding of the unsteady force production mechanisms, researchers have attempted to estimate the mechanical power of insect flight based on unsteady aerodynamic forces. Sane and Dickinson (2001), using the measured unsteady drag of a model fruit fly wing, showed that the mechanical power for a fruit fly was approximately twice as much as the previous estimate based on quasi-steady theory (Lehmann and Dickinson, 1997). Recently, Sun and Tang (2002b), through unsteady flow simulation by the CFD method, studied the lift and power requirements of hovering flight in the fruit fly. Under conditions where the mean lift balanced the insect weight, they computed the required mechanical power. With the computed mechanical power and available metabolic data, a value of 0.17 for the muscle efficiency was obtained, and was approximately twice as much as that estimated using the quasi-steady theory (0.09; Lehmann and Dickinson, 1997).
Though the above works on unsteady mechanisms of force production and power requirements were primarily concerned with hovering flight, it is believed that the unsteady mechanisms of force production are also applicable to the case of forward flight. In fact, flow visualization experiments on the tethered hawkmoth (Ellington et al., 1996; Willmott et al., 1997) have already shown that the delayed stall mechanism operates at advance ratios ranging from 0 to 0.9. However, the flow visualization results for the tethered insect were not so clear-cut because of the difficulty in obtaining good flow visualization near the wings. It is of interest to investigate the flow around the flapping wings during forward flight in more detail. For the power requirements in forward flight, Ellington et al. (1990), measured the oxygen consumption of bumblebees and showed that the metabolic power changed little from hovering to intermediate flight speeds. Assuming that muscle efficiency was constant over different flight speeds, it was concluded that the mechanical power would vary with the flight speed according to a J-shaped curve (Ellington et al., 1990; Ellington, 1991). It is of great interest to calculate the mechanical power directly and to see how it varies with the flight speed.
We here investigate these problems using a virtual fruit fly. Systematic kinematic data on free-flying fruit flies are not available at present. Assumptions on the wing motion and its variation with flight speed are made on the basis of existing data from tethered and free-flying fruit flies and some data from other insects. The method of computational fluid dynamics is used in the study. In the method, the pressure and velocity fields around the flapping wing are obtained by solving the Navier-Stokes equations numerically; the lift and thrust and the torques due to the aerodynamic forces are calculated based on the flow pressure and velocities. The inertial torques due to the acceleration and rotation of the wing-mass are calculated analytically. From the aerodynamic and inertial torques, the mechanical power required for the flight is calculated.
The wing considered in the present study is the same as that used in the study of fruit fly lift and power requirements in hovering flight (Sun and Tang, 2002b). The planform of the wing is similar to that of a fruit fly wing and the wing section is an ellipse whose thickness is 12% of the aerofoil chord length, and the radius of the leading and trailing edges is 0.2% of the aerofoil chord length. The radius of the second moment of wing area, r2, is 0.58R, where R is the wing length (the mean flapping velocity at span location r2 is used as reference velocity in the present study).
Three coordinate systems are used. Two are inertial coordinate systems, OXYZ and o′x′y′z′. For OXYZ, the origin O is at the wing base (see Fig. 1A); X and Y form the horizontal plane (X is in the direction of the free stream velocity), and the Z-direction is vertical. The coordinate system o′x′y′z′ has the same origin as the coordinate system OXYZ, its y′ axis coincides with the Y axis, and its o′x′y′ plane coincides with the stroke plane (see Fig. 1A,B). The third is the body-fixed coordinate system oxyz. It has the same origin as the two inertial coordinate systems, but it rotates with the wing. The x axis is parallel to the wing chord and the y axis is on the pitching-rotation axis of the wing (see Fig. 1C). The free-stream velocity, which has the same magnitude as the flight velocity, is denoted by V∞, and the stroke plane angle denoted by β (see Fig. 1A).
Sketches of the reference frames and wing motion. OXYZ is an inertial frame, with the XY plane in the horizontal plane. o′x′y′z′ is another inertial frame, with the x′y′ plane in stroke plane. oxyz is a frame fixed on the wing, with the x axis along the wing chord, and the y axis along the wing span. ϕ, positional angle of the wing; ϕmin and ϕmax, minimum and maximum positional angle, respectively; α, angle of attack of the wing; β, stroke plane angle; V∞, free-stream velocity; and R, wing length. CL and CT, coefficients of lift and thrust, respectively; Cl and Cd, coefficients of wing lift and wing drag, respectively; Cd′, x′ component of Cd..
The flow equations and computational method used in the present study are the same as those in Sun and Tang (2002a,b). Only an outline of the method is given here. The Navier-Stokes equations are solved using the algorithm developed by Rogers and Kwak (1990) and Rogers et al. (1991), which is based on the method of artificial compressiblity. The algorithm uses a third-order flux-difference splitting technique for the convective terms and the second-order central difference for the viscous terms. The time derivatives in the momentum equation are differenced using a second-order, three-point, backward-difference formula. The algorithm is implicit and has second-order spatial and time accuracy.
Once the Navier-Stokes equations are numerically solved, the fluid velocity components and pressure at discretized grid points for each time step are available. The aerodynamic forces and torques acting on the wing are calculated from the pressure and the viscous stress on the wing surface. The inertial torques due to the acceleration of the wing-mass are calculated analytically.
5 where ρ is the fluid density, U is the reference velocity (defined below), and S is the wing area. The formulae for the aerodynamic and inertial torques and the mechanical power were given in Sun and Tang (2002b) and will not be repeated here.
can be determined (around the next stroke reversal, the wing would rotate fromα =180°-αm to α=αm, so the sign of the right-hand side of Equation 8 should be reversed). It is assumed that the axis of the pitching rotation is located at 0.2c from the leading edge of the wing. Δτr is the wing rotation duration (or flip duration).
In the flapping motion described above, the reference velocity U, the velocity at midstroke Um, the geometric angle of attack at midstroke αm, the deceleration/acceleration duration Δτt, the wing rotation durationΔτ r, the flip timing τr, the period of flapping cycle τc and the stroke plane angle β must be specified.
Ennos (1989) made observations of free forward flight of two fruit flies Drosophila melanogaster, one at advance ratio 0.16 and the other at advance ratio 0.33. Ellington (1984a) made observations of free hovering flight of craneflies, hoverflies and droneflies (and many other insects). Their data show that the deceleration/acceleration duration Δτt and the duration of wing rotationΔτ r are approximately 0.2τc, and that wing rotation is symmetrical. It is assumed here thatΔτ t=0.18τc andΔτ r=0.24τc (these values were used in previous work on fruit fly lift and power requirements in hovering flight; Sun and Tang, 2002b) and that the wing rotation is symmetrical (as a result, τr may be determined).
To determine the reference velocity U and some other parameters, data in the previous study on free hovering in Drosophila virilis (Sun and Tang, 2002b) are used again here. These data were taken from Weis-Fogh (1972, 1973) and they are as follows: insect weight is 1.96×10-5 N, wing length R is 0.3 cm, area of both wings St is 0.058 cm2, stroke amplitude ϕ is 150°, and stroke frequency n is 240 s-1. The reference velocity is determined as U(=2ϕnr2)=218.7 cm s-1 (for all cases considered in the present study, the reference velocity, reference length and reference time are fixed as U=218.7 cm s-1, c=0.108 cm and c/U=0.495×10-3 s).
To determine U+m and τc (U/nc), data on how the stroke amplitude and stroke frequency vary with flight speed are needed. They are not available for fruit flies in free flight. Studies on the free flight of bumblebees (Dudley and Ellington, 1990a) and the hawkmoth (Willmott and Ellington, 1997a) showed that for both insects, the stroke frequency was constant. For bumblebees, the stroke amplitude did not vary significantly, but for the hawkmoth, the stroke amplitude varied with flight speed. Studies on tethered Drosophila virilis (Vogel, 1967) showed that the stroke frequency was constant and the stroke amplitude varied with flight speed. But in tethered D. melanogaster, Lehmann and Dickinson (1997) showed that both frequency and stroke amplitude changed with flight force. In the present study, we examine three different cases. (1) It is assumed that the stroke amplitude and stroke frequency do not vary with flight speed (ϕ=150° and n=240 s-1). (2) The stroke amplitude is allowed to vary with flight speed and is determined by force balance condition (frequency kept constant, n=240 s-1). (3) The frequency is allowed to vary with flight speed and is determined by force balance condition (stroke amplitude kept constant, ϕ=150°).
9 The Reynolds number Re and the mean lift coefficient required for supporting the insect weight C̄L,w are calculated as follows: Re=cU/ν=147 (ν=147 cm2 s-1); C̄L,w=1.96×10-5 N/0.5ρU2St=1.15 (ρ=1.23×10-3 g cm-3). The advance ratio J is defined as J=V∞/(UR/r2), and in the present study, it ranged from 0.13 to 0.66 (when presenting the results in later sections, some results for hovering flight, J=0, are also included).
(A-H) Vorticity plots at half-wing length at various times during one cycle (advance ratio J=0.27). τ is 60°, non-dimensional time;τ c is 60°, non-dimensional period of one cycle; α, angle of attack of wing. Solid and broken lines indicate positive and negative vorticity, respectively. The magnitude of the non-dimensional vorticity at the outer contour is 1 and the contour interval is 1. (A-D), downstroke; (E-H), upstroke.
The code used here is the same as that in the study of fruit fly lift generation and power requirements in hovering flight (Sun and Tang, 2002a,b). It is based on the flow computation method outlined above, and was developed by Lan and Sun (2001a). It was verified by the analytical solutions of simple flows [boundary layer flow on a flat plate (Lan and Sun, 2001a); flow at the beginning of a suddenly started aerofoil (Lan and Sun, 2001b)] and tested by measured steady-state pressure distributions on a wing (Lan and Sun, 2001a).
In earlier studies (Sun and Tang, 2002b), the code was tested by measured unsteady aerodynamic forces on a model fruit fly wing in flapping motion (Dickinson et al., 1999; the wing geometry was obtained from Prof. M. H. Dickinson). Three cases of wing rotation timing were considered (the stroke amplitude was 160° and the midstroke geometric angle of attack was 40°), but only the lift forces were compared. In a recent paper by Sane and Dickinson (2001), both lift and drag on the same model wing are given for a wide range of wing kinematic parameters. Here, we make further comparisons between calculations and experiments, using the data of Sane and Dickinson (2001). The computed and measured lift and drag coefficients are shown in Fig. 2 [for results in Fig. 2A,B, the stroke amplitude is 60° and the midstroke geometric angle of attack is 50°; for results in Fig. 2C,D, these parameters have values of 180° and 50°, respectively; experimental data are taken from fig. 3C,D of Sane and Dickinson (2001)].
Comparison of the calculated and measured lift (CL) and drag (Cd) coefficients. The experimental data are reproduced from fig. 3C,D of Sane and Dickinson (2001). (A,B) The midstroke angle of attack αm is 50° and stroke amplitude ϕh is 60°. (C,D) The midstroke angle of attackα m is 50° and stroke amplitude ϕh is 180°. τ, non-dimensional time; τc, non-dimensional period of one flapping cycle.
(A), lift coefficient CL (B), thrust coefficient CT (C), wing lift coefficient C1 (D), wing drag coefficient Cd (E) and x′ component of wing drag coefficient Cd′ (F) versus time during one cycle for five advance ratios. J. τc, non-dimensional period of one flapping cycle; τ, non-dimensional time (midstroke angle of attack αm and stroke plane angle β vary with flight speed; stroke amplitude Φh=150°).
The calculated drag coefficient agrees well with the measured (see Fig. 2A,C). For the lift coefficient (see Fig. 2B,D), in the translational phase of the downstroke, the computed value agrees well with the measured; around the stroke reversal, the computed peak values are smaller than the measured; in the translational phase of the upstroke, the computed value is a little less than the measured, but they are in qualitative agreement (note that the value of the measured lift coefficient in the upstroke is higher than that in the downstroke). The above is also true in the lift coefficient comparisons in Sun and Tang (2002b) [see fig. 4 of Sun and Tang (2002b); there the downstroke was plotted as the second half of the flapping cycle].
(A-H) Vorticity plots at half-wing length at various times during one cycle (advance ratio J=0). τ, non-dimensional time; τc, non-dimensional period of one cycle; α, angle of attack of wing. Solid and broken lines indicate positive and negative vorticity, respectively. The magnitude of the non-dimensional vorticity at the outer contour is 1 and the contour interval is 1. (A-D), downstroke; (E-H), upstroke.
The above comparisons show that although the CFD simulations might not capture accurately all the flow features around the stroke reversal, the agreement of the aerodynamic force coefficients between the computational and experimental simulations is reasonably good. We think that the present CFD method can calculate the unsteady aerodynamic forces and torques of the model insect wing with reasonable accuracy.
In the above calculations, the computational grid has dimensions 93×109×71 in the normal direction, around the wing section and in the spanwise direction, respectively. The normal grid spacing at the wall was 0.002. The outer boundary was set at 10 chord lengths from the wing. The time step was 0.02. Detailed studies of the numerical variables such as grid size, domain size, time step, etc., were conducted in our previous work on the unsteady lift mechanism of a flapping fruit fly wing (Sun and Tang, 2002a,b), where it was shown that the above values for the numerical variables were appropriate for the flow calculation. Therefore, in the following calculation, the same set of numerical variables is used.
Since we wished to study the aerodynamic force and power requirements for balanced flight, we first investigated the force balance. In the study of hovering flight by Sun and Tang (2002b), there was no body drag. The stroke plane was assumed to be horizontal (β=0) and the mean thrust was zero, therefore the horizontal force was balanced. The midstroke angle of attack αm was adjusted such that the weight of the insect was balanced by the mean lift.
In forward flight, the body drag is not zero and the stroke plane is tilted forward to produce thrust. At a given flight speed or advance ratio, for different values of αm and β, the mean lift and mean thrust are different (the stroke amplitude ϕ and stroke frequency n were assumed to be constant). αm and β at a given flight speed are determined using the force balance condition (mean lift equals the weight and mean thrust equals the body drag).
The calculation procedure is as follows. A flight speed is specified. A set of values for αm and β is guessed; the flow equations are solved and the corresponding mean lift and thrust coefficients C̄L and C̄T are calculated. The body drag for the given flight speed and body angle (body angle is related toβ by Equation 9) is obtained from Vogel (1966). The C̄L was compared with C̄L,W and the mean thrust (=0.5ρU2StC̄T) is compared with the body drag. If C̄L is not equal to C̄L,W or the mean thrust is not equal to the body drag, then αm and β are adjusted [the gradients of C̄L (and C̄T) with respect toα m and β are used as markers for adjustingα m and β]; and the calculations are repeated until the magnitudes of difference between C̄L and C̄L,W and between C̄T and body drag (divided by 0.5ρU2St) are less than 0.01.
The calculated results for four forward flight speeds are shown in Table 1 (the results for hovering flight are also included). It is seen that C̄L is close to 1.15, as it should be. C̄T increases almost linearly with flight speed, as does the body drag. (For a fixed body angle, the drag would increase more rapidly than linearly with flight speed; but here the body angle decreased with flight speed.) αm is close to that that of hovering flight at small and medium speeds (J=0.13, 0.27; V∞=0.5, 1.0 m s-1) but increases to large values at higher speeds. β increases almost linearly with flight speed. From the ratio between C̄T and C̄L, the orientation of the total force vector can be calculated. At hovering, β=0, and the total force vector is vertical; at medium speed (J=0.27; V∞=1.0 m s-1), β=29°, and the total force vector tilts forward by 4.4°; at high speed (J=0.53; V∞=2.0 m s-1), β=60°, and the total force vector tilts forward by 10°.
Here, we investigate how the lift and the thrust on the insect are generated.
As seen in Fig. 3B,C, at low flight speed (J=0.13), CL in the upstroke is smaller than that in the downstroke; both down- and upstroke contribute to the mean lift, but approximately 75% of it is from the downstroke. Negative thrust is produced in the downstroke and positive thrust in the upstroke, but the amount of the positive thrust in the upstroke is larger than that of negative thrust in the downstroke, resulting in a positive mean thrust. Therefore, the mean thrust is contributed by the upstroke (the downstroke has negative contribution).
At medium flight speed (J=0.27), CL is large in the downstroke but very small in the upstroke, so the mean lift is mainly contributed by the downstroke. Similar to the case of low speed, the mean thrust is contributed by the upstroke (the downstroke has negative contribution).
At high flight speed (J=0.53), CL in the downstroke is even larger, and CL in the upstroke is negative but is of small magnitude. Therefore, the mean lift is contributed by the downstroke (the upstroke has negative contribution). Positive thrust is produced in the downstroke (because in this case, the stroke plane angle is large, β=60°), and relatively large positive thrust is produced in the upstroke; approximately 74% of the mean thrust is from the upstroke.
The lift and thrust coefficients (CL and CT, respectively) shown above are the results of the wing lift and wing drag coefficients (Cl and Cd, respectively). In fact, only the x′ component of Cd (Cd′; see Fig. 1B,C) contributes to CL and CT (Cd is relevant to the aerodynamic power of the wing). The corresponding Cl, Cd and Cd′ values are shown in Fig. 3D-F.
At low speed (J=0.13), as shown above, 75% and 25% of the mean lift are contributed by the downstroke and the upstroke, respectively. In most of the downstroke, the magnitudes of Cl and Cd are approximately the same. Since β is not very large (β=16.5°), the major part of CL is from Cl, and approximately 20% of CL is from Cd′. In the upstroke, Cd′ has negative contribution to CL. Also as shown above, the mean thrust is contributed by the upstroke; in the upstroke, it is Cd′ that gives the major portion of the thrust, and Cl contributes approximately 20% of CT. Therefore, it can be stated that the mean lift is contributed by the wing lift of both the down- and upstrokes (the contribution of downstroke is approximately three times as large as that of upstroke), and that the mean thrust is contributed mainly by the x′ component of the wing drag of the upstroke.
At medium flight speed (J=0.27), as shown above, the mean lift is contributed mainly by the downstroke and the mean thrust is contributed by the upstroke. In the downstroke, Cl and Cd′ have same sign and are approximately of the same magnitude (around 1.8), and in the upstroke, Cl is mostly positive and Cd′ is negative, and they are also approximately of the same magnitude. Noting that β is about 30°, it can be stated that the mean lift is contributed almost equally by the wing lift and the x′ component of the wing drag of the downstroke, and that the mean thrust is contributed almost equally by the wing lift and the x′ component of the wing drag of the upstroke.
At high flight speed (J=0.53; αm=56°,β =60°), based on similar analysis, it can be stated that the mean lift is contributed mainly by the the x′ component of the wing drag of the downstroke (note the similarity between Cd′ in Fig. 3F and CL in Fig. 3B during the downstroke), and that a relatively large part of the mean thrust is contributed by the x′ component of the wing drag of the upstroke and a relatively small part of the mean thrust is contributed by the wing lift of the downstroke.
The mechanisms of unsteady force production by the model fruit fly wing in the case of hovering flight were studied by Dickinson et al. (1999) and Sun and Tang (2002a). It was shown that (for symmetrical rotation) the peak in Cd and the dip in Cl at the beginning of a down- or upstroke (see Cl and Cd for J=0 in Fig. 3D,E) were due to the combined effects of acceleration and rotation of the wing; the large Cl and Cd (around 1.2) during the translational phase of the down- or upstroke were due to the delayed stall mechanism, and the peaks in Cl and Cd near the end of the down- or upstroke were due to the pitching-up rotation of the wing.
In the case of forward flight, as shown in Fig. 3D,E, the Cl and Cd peaks near the end of the strokes and the Cd peak and Cl dip at the beginning of the strokes still exist and are similar to those in the case of hovering flight. This is because at the beginning or the end of a stroke, the positional angle of the wing is either near ϕmin orϕ max (see Fig. 1C) where the component of the free-stream velocity that is normal to the wing span is small, and as a result the free-stream velocity has very limited effect on the force production of the wing there. The difference in size of the peaks for various advance ratios were mainly caused by the difference in rotation rate of the wing. Therefore, the force production mechanisms at the beginning and near end of the strokes in forward flight are the same as that in hovering flight.
We now consider Cl and Cd in the translatory phase of the down- or upstroke (the middle 64% of the down- or upstroke). In order to assist the analysis of the force coefficients, the contours of the non-dimensional spanwise component of vorticity at mid-span location are given in Figs 4, 5, 6 for J=0, 0.27 and 0.53, respectively, and the corresponding sectional streamline plots (seen in the body-fixed frame oxyz) are given in Figs 7, 8, 9.
(A-H) Vorticity plots at half-wing length at various times during one cycle (advance ratio J=0.53). τ is 60°, non-dimensional time;τ c is 60°, non-dimensional period of one cycle; α, angle of attack of wing. Solid and broken lines indicate positive and negative vorticity, respectively. The magnitude of the non-dimensional vorticity at the outer contour is 1 and the contour interval is 1. (A-D), downstroke; (E-H), upstroke.
Sectional streamline plots at half-wing length at various times during one cycle (advance ratio J=0). τ, non-dimensional time;τ c, non-dimensional period of one cycle; α, angle of attack of wing (the spatial interval of the incoming streamlines can be seen from the left or right of a plot). (A-C), downstroke; (D-F), upstroke.
Sectional streamline plots at half-wing length at various times during one cycle (advance ratio J=0.27). τ, non-dimensional time;τ c, non-dimensional period of one cycle; α, angle of attack of wing (the spatial interval of the incoming streamlines can be seen from the left or right of a plot). (A-C), downstroke; (D-F), upstroke.
Sectional streamline plots at half-wing length at various times during one cycle (advance ratio J=0.53). τ, non-dimensional time;τ c, non-dimensional period of one cycle; α, angle of attack of wing (the spatial interval of the incoming streamlines can be seen from the left or right of a plot). (A-C), downstroke; (D-F), upstroke.
For the case of medium flight speed (J=0.27; β=29°;α m=34°), during the translatory phase of the downstroke (τ=0.09∼0.41τc), similar to the case of hovering, both Cl and Cd maintain large and almost constant values (see Fig. 3D,E). From Fig. 5B-D (and Fig. 8A-C), it is seen that during this period, the LEV does not shed. Therefore, maintaining the large Cl and Cd during this period is due to the delayed stall mechanism. Cl is approximately 2.1 and Cd approximately 1.8. Both are larger than in hovering flight (approximately 1.4 and 1.2, respectively). This is because during the downstroke of forward flight, due to the free-stream velocity, the wing sees a relative velocity that has a larger magnitude and a slightly smaller effective angle of attack (the z′ component of V∞ acting to decrease the effective angle of attack). During the translatory phase of the upstroke (τ=0.59∼0.91τc), both Cl and Cd are much smaller than that of hovering flight. This is because during the upstroke, the wing sees a relative velocity that has a smaller magnitude and a smaller effective angle of attack (in the upstroke, since the magnitude of the relative velocity is small, the same z′ component of V∞ causes a greater decrease in effective angle of attack than in the downstroke). Comparing the streamline plots for J=0.27 in Fig. 8D-F and that for J=0 in Fig. 7D-F, it is seen that the streamlines in front of the wing for J=0.27 have a much smaller angle of attack than that for J=0. From Fig. 5D-F, it is interesting to see that during the upstroke of forward flight, due to the smaller effective angle of attack, the vorticity on the upper surface of the wing is only a little different from that on the lower surface.
It should be noted that the effective angle of attack varies during a downstroke or upstroke. For example, in Fig. 7 (J=0), during the downstroke (Fig. 7A-C), the effective angle of attack is small at the early part of the stroke (Fig. 7A), and becomes larger in the later part of the stroke (Fig. 7B,C); the same is true during the upstroke (Fig. 7D-F). (Similar variation of effective angle of attack during a down- or upstroke can be seen in Figs 8, 9). This is because, as explained in Birch and Dickinson (2001) and Sun and Tang (2002a), during the stroke reversal the wing rotation induced a downwash, which decreased the effective angle of attack of the wing in the early part of the following stroke.
The above discussion helps to explain the negative Cl at the early part of the upstroke in the cases of higher advance ratios (Fig. 3D,J=0.27-0.53). At higher advance ratios, β is relatively large, and so is the `downwash' velocity due to V∞. This `downwash' velocity together with the induced downwash velocity by wing rotation makes the effective angle of attack to be around zero (see Figs 8D, 9D,E), resulting in the negative Cl.
Finally, we consider the wing drag Cd (see Fig. 3E). At low and medium flight speeds (J=0.13, 0.27), in the downstroke, the magnitude of Cd is larger than that of hovering (J=0), yet in the upstroke it is slightly smaller than that of hovering, indicating that the average of the magnitude of Cd over a flapping cycle is a little smaller than that of hovering. But at high flight speed (J=0.53), in the downstroke, the magnitude of Cd is much larger than that of hovering, and in the upstroke, it is only a little smaller than that of hovering, indicating that the average of the magnitude of Cd over a cycle is much larger than that of hovering. Since the aerodynamic power is mainly determined by Cd (the inertial power for Drosophila is relatively small; Sun and Tang, 2002b), it is foreseen that the mechanical power at low and medium flight speeds is a little smaller that of hovering and increases rapidly at higher flight speeds.
As shown above, at a given flight speed, when αm andβ were properly chosen, the insect produced enough lift and thrust to support its weight and to overcome the body drag, respectively. We calculated the power required for production of the above lift and thrust, and investigated its properties and how it varied with the flight speed.
As expressed in equation 20 of Sun and Tang (2002b), the aerodynamic power consists of two parts, one due to the aerodynamic torque for translation and the other to the aerodynamic torque for rotation. The coefficients of these two torques, CQ,a,t and CQ,a,r, are shown in Fig. 10A,B (for clarity, only the results for J=0, 0.27 and 0.53 are shown). CQ,a,t is much larger than CQ,a,r. The CQ,a,t curve is similar in shape to the Cd curve shown in Fig. 3E, for obvious reasons.
Aerodynamic torque coefficients for translation CQ,a,t (A) and for rotation CQ,a,r (B) and inertial torque coefficients for translation CQ,i,t (C) and for rotation CQ,i,r (D) versus time in one cycle for various advance ratios J. τ, non-dimensional time; τc, non-dimensional period of one cycle.
With the above results for the aerodynamic and inertial torque coefficients, the power coefficients can be computed using equations 41-43 of Sun and Tang (2002b). The coefficients of power for translation (CP,t) and for rotation (CP,r) are plotted against the non-dimensional time in Fig. 11. Throughout a flapping cycle, the magnitude of CP,t is much larger than that of CP,r. CP,t varies with flight speed in the same way as the wing drag coefficient Cd does. That is, at low to medium flight speeds (J=0.13-0.27), the average of CP,t over a flapping cycle is a little smaller than that of hovering, but at high flight speed (J=0.53), the average of CP,t is much larger than that of hovering. This indicates that the power requirement at low to medium speeds is a little smaller than that of hovering, and becomes much larger at higher speeds.
Coefficients of power for translation CP,t (A) and for rotation CP,r (B) versus time in one cycle for various advance ratios J. τ, non-dimensional time;τ c, non-dimensional period of one cycle (midstroke angle of attack αm and stroke plane angle β vary with flight speed; stroke amplitude ϕ=150°).
From Fig. 11 it is also seen that at hovering (J=0), CP,t is the same during the down- and upstrokes, but at forward flight, especially at medium and high speeds (J=0.27-0.53), CP,t during the downstroke is much larger than CP,t during the upstroke. At J=0.13, 0.27 and 0.53, average values of CP,t over the downstroke are approximately 1.6, 2.6 and 3.5 times as much as that over the upstroke, respectively. This indicates that in forward flight, the flight muscle of the insect must do significantly more work during the downstroke than during the upstroke.
Integrating CP,t over the part of a wingbeat cycle where it is positive gives the coefficient of positive work for translation, which is represented by C+W,t. Integrating CP,t over the part of the cycle where it is negative gives the coefficient of `negative' work for `braking' the wing in this part of the cycle, which is represented by C-W,t. Similar integration of CP,r gives the coefficients of positive and negative work for rotation; and they are denoted by C+W,r and C-W,r, respectively. The results of the integration are shown in Table 1.
10 where Cw is the coefficient of work per cycle.
11 Sun and Tang (2002b) pointed out that for the insect considered, the negative work is much smaller than the positive work and Cw calculated by considering the other possibilities would not be very different from that by Equation 11. This is also true here, as seen from the values of C-W,t + C-W,r in Table 1. Therefore, in the present study, Equation 11 is employed for calculation of Cw.
The calculated results of Cw are also given in Table 1. With Cw known, the specific power P* was computed using Equation 10, and is plotted against flight speed in Fig. 12 (see the circles in the figure). At J=0.13 and 0.27, P* is only approximately 10% smaller than that of hovering; at J=0.40, P* is about the same as that of hovering; but at J=0.53, P* is approximately 41% larger than that of hovering. As foreseen above (on the basis of the variation of Cd with flight speed), the power requirement at low to intermediate speeds is a little smaller than that of hovering, and it increases rapidly at higher flight speeds.
Body-mass-specific power P* versus advance ratios J. αm, midstroke angle of attack; β, stroke angle; ϕ, stroke amplitude; n, stroke frequency.
For a given flight speed, ϕ and β were chosen such that the lift and thrust balanced the insect weight and the body drag, respectively. The calculation procedure was similar to that in the case of αm and β varying with flight speed (see above).
The lift (vertical force) and thrust coefficients (CL and CT) versus non-dimensional time for various advance ratios are shown in Fig. 13B,C. They are similar to their counterparts in the case ofα m and β varying with flight speed (see Fig. 3B,C). At low flight speed (J=0.13), both the down- and upstrokes contribute to the mean lift but approximately 80% of the mean lift is from the downstroke; the mean thrust is contributed by the upstroke (the downstroke has negative contribution). At medium flight speed (J=0.27), the mean lift is contributed by the downstroke, and the mean thrust is contributed by the upstroke (the downstroke has negative contribution). At high flight speed (J=0.53), the mean lift is contributed by the downstroke (the upstroke has a small negative contribution), and the mean thrust is contributed almost equally by the down- and upstrokes (in the case of αm and β varying with flight speed, at high flight speed, the upstroke has relatively large contribution to the mean thrust).
(A), lift coefficient CL (B), thrust coefficient CT (C), wing lift coefficient Cl (D), wing drag coefficient Cd (E) and x′ component of wing drag coefficient Cd′ (F) versus time during one cycle for five advance ratios J. τc, non-dimensional period of one flapping cycle; τ, non-dimensional time (stroke amplitude Φ and stroke plane angle β vary with flight speed; midstroke angle of attack αm=46.5°; stroke frequency n=240 s-1).
The wing lift and drag coefficients (Cl, Cw and Cd′) versus non-dimensional time for various advance ratios are shown in Fig. 13D-F, and are also similar to their counterparts in the case of αm and β varying with flight speed (see Fig. 3D-F). Using the flow field information (vorticity contours and streamline patterns around the wing), it was shown that the mechanisms operating in the generation of Cl and Cd in the present case were the same as that in the case of αm and β varying with flight speed.
The coefficients of power for translation and for rotation versus non-dimensional time are shown Fig. 14; again they are very similar to their counterparts in the case of αm and β varying with flight speed (see Fig. 11). At low speed (J=0.13), medium speed (J=0.27) and high speed (J=0.53), the average values of CP,t over the downstroke are approximately 1.6, 2.8 and 4.2 times as large as that over the upstroke, respectively.
Coefficients of power for translation CP,t (A) and for rotation CP,t (B) versus time in one cycle for various advance ratios J. τ, non-dimensional time;τ c, non-dimensional period of one cycle (stroke amplitude ϕ and stroke plane angle β vary with flight speed; midstroke angle of attack αm=46.5°; stroke frequency n=240 s-1).
The coefficients of work per cycle (Cw), calculated in the same way as in last section, are shown in Table 2. With Cw, the specific power P* was computed and the results shown Fig. 12 (triangles). It is seen that P* in the present case is approximately the same as that in the case of αm and β varying with flight speed.
In this section, we consider the case in which the stroke frequency n and stroke plane angle β were allowed to vary with flight speed (αm and ϕ were assumed constant;α m=46.5°, ϕ=150°; other parameters were the same as in the above two cases).
For a given flight speed, n and β were chosen such that lift and thrust balance the insect weight and body drag, respectively. The calculation procedure was similar to that in the case of ϕ and β varying with flight speed).
The calculated C̄L, C̄T, n, β and Cw as functions of advance ratio are shown in Table 3. (Similar to the above two cases, we have results up to J=0.53. At J=0.66, no matter how n and β were adjusted, enough lift could not be obtained.) Comparing the results in Table 3 (n varying with flight speed) and in Table 2 (ϕ varying with flight speed) shows that n varies with flight speed in the same way as ϕ does in their respective cases. Note that at each of the advance ratios (or flight speeds) considered, nϕ is approximately the same for the two cases. This shows that (in the range of ϕ and n considered in the present study), the insect can change its ϕ or n by approximately the same percentage to produce a similar change of aerodynamic force. The reason for this is obvious: the aerodynamic force is approximately proportional to the square of the translational velocity of the wing, which is proportional to nϕ.
The specific power P* is given in Fig. 12 (see the squares in the figure). P* is almost the same as that in the other two cases.
In the above analyses, we considered three cases where αm,β , ϕ and n varied with flight speed. In the first case,α m and β varied with flight speed and ϕ and n were constant (ϕ=150°, n=240 s-1); in the second case, ϕ and β varied with flight speed andα m and n were constant (αm=46.5°, n=240 s-1); in the third case, n and β varied with flight speed and αm and ϕ were constant (αm=46.5°,ϕ=150°). In all the three cases, when the advance ratio was increased to J=0.66 (V∞=2.5 m s-1), enough lift to balance the weight could not be obtained. For reference, we conducted an additional calculation at J=0.66, in which ϕ, αm and β could be adjusted (n fixed as 240 s-1).
It was shown that when ϕ=160°, αm=71° andβ =70°, the lift and thrust balanced the weight and the body drag, respectively. The thrust coefficient CT was 0.27; the body angle χ was -2°. The specific power P* was included in Fig. 12 (see the dot in the figure); it is about three times as large as that of hovering, and it is believed that the insect does not fly at such a speed for flights of long duration.
12 For example, using data of the model fruit wing (ϕ=150°, R/c=3), when J=0.53 and β=53°,Λ d is 6.6.
Dudley and Ellington (1990a,b) systematically studied the kinematics, lift and power requirements of forward flight in bumblebees. On the basis of wing kinematics and quasi-steady aerodynamic theory, they demonstrated that the downstoke progressively became more important in production of the lift (vertical force) as flight speed increased. They considered that quantitative treatment of the relative contributions to the thrust generation of the downstroke and upstroke was not possible at the time, because the condition of horizontal force balance could not be satisfied in the analysis. In a subsequent paper by Ellington (1995), on the basis of a further analysis of the data from Dudley and Ellington (1990a), it was demonstrated that, as the advance ratios increased, the downstroke would increasingly dominate weight support, and that the upstroke contributed thrust at all speeds but its contribution decreased with increasing forward speed, a trend that was offset by an increasing thrust component from the downstroke force.
The present results on the aerodynamic roles of the down- and upstrokes of the Drosophila virilis in forward flight are in agreement with those of bumblebees by Dudley and Ellington (1990a,b) and Ellington (1995), although the results for bumblebees were based on steady-state aerodynamic analysis.
In previous studies on power requirements of forward flight of insects, to the author's knowledge, the relative contributions to the mechanical power of the downstroke and the upstroke were not mentioned (only the mean power over a flapping cycle was presented). The present study (see Figs 11, 14) showed that although in hovering with a horizontal stroke plane the work done in the downstroke was the same as that in the upstroke, in forward flight, even at low flight speed, the work done in the downstroke was considerably more than that done in the upstroke. In the case of β and ϕ varying with flight speed, at advance ratios J=0.13, 0.27 and 0.53, the work done in the downstroke was approximately 1.6, 2.8 and 4.2 times as much as that in the upstroke.
The measured oxygen consumption of bumblebees and a hummingbird in forward flight showed little dependence of metabolic power on speed from hovering to intermediate speeds, and for the hummingbird, a sharp increase at higher speeds (measurement for bumblebees at higher speeds are not available; for a review, see Ellington, 1991). If the muscle efficiency of the animals is assumed constant over various speeds, the mechanical power would vary with speed according to a J-shaped curve (Ellington et al., 1990; Ellington, 1991).
From results of the present study, this is approximately true for fruit fly Drosophila virilis. As illustrated in Fig. 12, at hovering, the body mass-specific power P* is approximately 29 W kg-1; at J=0.13 and 0.27, P* is only approximately 10% less than that of hovering; at J=0.4, P* is almost the same as that of hovering; but when J is furthered increased, P* has a sharp increase (at J=0.53, P* is approximately 40% larger than that of hovering, and at J=0.66, P* is approximately 150% larger than that of hovering). That is, the graph of the specific power against flight speed is approximately J-shaped.
From Fig. 13, it is seen that at J=0.4, the power is a little larger than that at lower speeds and is almost the same as that of hovering, and afterwards the power increases sharply. This indicates that the insect would usually fly at advance ratios between 0 and 0.4, and that for fast flight, it would fly at an advance ratio around 0.4. (Flying at higher advance ratios would be very energy-demanding.) No data are available for Drosophila virilis in free forward flight; there exist some data for Drosophila melanogaster, however. Ennos (1989) observed D. melanogaster flying at J=0.33. Marden et al. (1997) showed that the upper limit of D. melanogaster flight speed was around 0.85 m s-1. The corresponding advance ratio is around 0.32, estimated using the measured (Ennos, 1989) stroke angle (150°) and stroke frequency (254 s-1) of free flying D. melanogaster (wing length R=2 mm). David (1978) recorded a maximum advance ratio of about 0.4 for D. melanogaster in experimental setting. The present computed results are consistent with these observations.
We thank the two referees whose helpful comments and valuable suggestions greatly improved the quality of the paper. This research was supported by the National Natural Science Foundation of China.
David, C. T. (1978). The relationship between body angle and flight speed in free-flying Drosophila. Phys. Ent. 3,191 -195.
Dudley, R. and Ellington, C. P. (1990a). Mechanics of forward flight in bumblebees. I. Kinematics and morphology. J. Exp. Biol. 148,19 -52.
Dudley, R. and Ellington, C. P. (1990b). Mechanics of forward flight in bumblebees. II. Quasi-steady lift and power requirements. J. Exp. Biol. 148, 53-88.
Ellington, C. P. (1984a). The aerodynamics of hovering insect flight. III. Kinematics. Phil. Trans. R. Soc. Lond. B 305,41 -78.
Ellington, C. P. (1984b). The aerodynamics of hovering insect flight. IV. Aerodynamic mechanisms. Phil. Trans. R. Soc. Lond. B 305,79 -113.
Ellington, C. P. (1984c). The aerodynamics of hovering insect flight. VI. Lift and power requirements. Phil. Trans. R. Soc. Lond. B 305,145 -181.
Ellington, C. P. (1991). Limitations on animal flight performance. J. Exp. Biol. 160, 71-91.
Ellington, C. P. (1995). Unsteady aerodynamics of insect flight. In Biological Fluid Dynamics. Symp. Soc. Exp. Biol. 49 (ed. C. P. Ellington and T. J. Pedley), pp. 109-129. Cambridge: Company of Biologists.
Ellington, C. P., Machin, K. E. and Casey, T. M. (1990). Oxygen consumption of bumblebees in forward flight. Nature 347,472 -473.
Lan, S. L. and Sun, M. (2001a). Aerodynamic of properties of a wing performing unsteady rotational motions at low Reynolds number. Acta Mech. 149,135 -147.
Lan, S. L. and Sun, M. (2001b). Aerodynamic interaction between two airfiols in unsteady motions. Acta Mech. 150,39 -51.
Marden, J. H., Wolf, M. R. and Weber, K. E. (1997). Aerial performance of Drosophila melanogaster from populations selected for upwind flight ability. J. Exp. Biol. 200,2747 -2755.
Rogers, S. E. and Kwak, D. (1990). Upwind differencing scheme for the time-accurate incompressible Navier-Stokes equations. AIAA J. 28,253 -262.
Rogers, S. E., Kwak, D. and Kiris, C. (1991). Numerical solution of the incompressible Navier-Stokes equations for steady-state and dependent problems. AIAA J. 29,603 -610.
Sun, M. and Tang, J. (2002b). Lift and power requirements of hovering flight in Drosophila. J. Exp. Biol. 205,2413 -2427.
Vogel, S. (1966). Flight in Drosophila. I. Flight performance of tethered flies. J. Exp. Biol. 44,567 -578.
Vogel, S. (1967). Flight in Drosophila. II. Variations in stroke parameters and wing contour. J. Exp. Biol. 46,383 -392.
Weis-Fogh, T. (1973). Quick estimates of flight fitness in hovering animals, including novel mechanism for lift production. J. Exp. Biol. 59,169 -230.
Willmott, A. P. and Ellington, C. P. (1997b). The mechanics of flight in the hawkmoth Manduca sexta. II. Aerodynamic consequences of kinematic and morphological variation. J. Exp. Biol. 200,2723 -2745.
Willmott, A. P., Ellington, C. P. and Thomas A. R. (1997). Flow visualization and unsteady aerodynamics in the flight of the hawkmoth, Manduca sexta. Trans. R. Soc. Lond. B 352,303 -316.
Wu, J. C. (1981). Theory for aerodynamic force and moment in viscous flows. AIAA J. 19,432 -441.


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Monday, 15 September 2008: Starwood Hotels & Resorts Worldwide, Inc. , recently announced it has signed an agreement with C.M. Enterprises to develop an aloft hotel in Nanhai Science & Technology Industrial Park, Foshan City of Guangdong Province in China. Set to debut in 2010, the 200-room hotel will be the first international branded hotel to open in Nanhai.
"We are thrilled with the signing of aloft Nanhai – Foshan! This signing is certainly timely, especially with the upcoming opening of our first aloft in Asia and in China: aloft Beijing – Haidian. Guests traveling to Foshan for business or pleasure won't have to settle for one or the other, thanks to aloft. Our bar w xyzSM is sure to be a hub of activity for locals and visitors alike, and our meeting space and guestrooms will inspire even the most jet-lagged business traveler," commented Mr. Qian Jin, Senior Vice President, Operations, China & Taiwan, Starwood Hotels & Resorts.
Located in the Nanhai Science & Technology Industrial Park, aloft Nanhai - Foshan will offer a fresh, fun and affordable way to enjoy Foshan City and all of the commercial, cultural and historical sites it has to offer.
As a Vision of W Hotels, aloft hotels are shaking up the lodging industry with urban-influenced design, accessible technology, style and a social atmosphere. aloft hotels offer a total sensory experience, with guestrooms featuring loft-like nine-foot ceilings and oversized windows to create a bright, airy environment. The centerpiece of the aloft room is the ultra-comfortable signature bed, and large stylish bathrooms that complement the guest experience with oversized walk-in showers and amenities created by Bliss? Spa. Each aloft room is also a combination high-tech office and entertainment center, featuring wireless internet access and plug & play, a one-stop connectivity solution for multiple electronic gadgetry such as PDAs, cell phones, mp3 players and laptops - all linked to a large flat panel HDTV ready television for optimal sound and viewing.
Designed in conjunction with world renowned David Rockwell and the Rockwell Group, aloft stays true to the W Hotel brand's heritage, offering atmospheric public spaces designed to draw guests from their rooms into sassy public spaces. Guests can work on their laptops via hotel-wide wireless internet access, play a game of pool or grab a drink with friends at the re:mixSM communal lobby area and bar w xyzSM. The re:chargeSM fitness center and splash, the indoor pool, give travelers options to d-stress and re-energize; while re:fuel by aloftSM, a one-stop food and beverage area, offers sweet, savory and healthy food, snacks and beverages to grab & go, 24-hours a day.


Established in 1946 as a small studio pottery in Gorey, we grew to become one of the Island's most popular tourist attractions. In the early 1960s we opened a "coffee bar" for visitors to the pottery. The original coffee bar was the beginning of JPRestaurants which, run by the third-generation, now includes Jersey Crab Shack.
We bring you a unique Jersey experience combining beautiful, relaxing locations, freshly-prepared delicious food and casual but attentive service with a warm Jersey Crab Shack smile.
From our first restaurant in St Brelade's overlooking the bay, to Gorey with the Castle vista and now St Helier in a restored historic market hotel, our team strive to bring you everything that's best about Jersey. With a wide choice of fish, meat, vegetarian and vegan dishes we also cater to those with food allergies and intolerance.


MILWAUKEE, WI - StoreWALL says its quick-installed InstallStrip for hanging slat wall, has becoming very popular. Since its introduction a little over a year ago, about 50 percent of StoreWALL installations are completed using the InstallStrip method.
The InstallStrip uses no visible fasteners, and installs on concrete block, steel studs, wood studs or drywall. The slat wall then hangs from it. One person can is able to do the full installation solo, says StoreWALL.


'The Elms', the Clifford V. Brokaw estate designed by Charles Platt c. 1912 in Glen Cove. The house has similarities to John T. Pratt's 'Manor House' (also by Charles Platt). Brokaw was a stockbroker who set a record in 1927 when he sold his seat on the NY Stock Exchange for $235,000 (he purchased it in 1918 for less than $60,000). Click HERE to see the farm group to 'The Elms'. The house was demolished c. 1947.
So there is a Long Island "The Elms" as well as the Newport "The Elms." Most interesting.
I wonder if any more Marble Houses existed on Long Island.
Lovely breakfast room; a bit chilly but lovely.


Washington, DC – This week, Congressman Howard L. Berman (D-CA) joined Congressman Ted Poe (R-TX) in introducing H.R. 2337, the Kate Puzey Peace Corps Volunteer Protection Act of 2011. This bipartisan legislation is in response to recent reports highlighting the need for the Peace Corps to improve its response to Volunteers who are the victims of violent crimes, risk reduction training, and confidentiality practices. Senators Johnny Isakson (R-GA) and Barbara Boxer (D-CA) are introducing the companion bill in the Senate.
"I strongly support the Peace Corps, which continues to do critical work in developing countries around the world 50 years after its founding by President John F. Kennedy," said Congressman Berman. "However, I am deeply troubled by recent reports that the Peace Corps provided inadequate support for Volunteers that were the victims of sexual assault and mishandled confidential information that contributed to the death of a volunteer.
The Kate Puzey Peace Corps Volunteer Protection Act of 2011 requires the Peace Corps to follow best practices in responding to sexual assaults, creates an additional three victim advocates to ensure that victims of violent crimes receive necessary services, sets up an Advisory Council to review Peace Corps' sexual assault policy and implementation, and establishes new confidentiality requirements.
Kate Puzey, for whom this legislation is named, was a Peace Corps Volunteer from Georgia who taught English in the small town of Badjoude, Benin. During her service, Kate was brutally murdered, and in her memory, the Puzey family has spearheaded the effort for Peace Corps reform.


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text:
A cruising couple mobilizes 'neighborhood' crime watch
Soundings Editors
Cruisers John and Melodye Pompa are on a mission: to make the Caribbean safer for both cruisers and islanders.
"I think the increase in crime against yachts is spillover from crimes against residents and citizens on land," says Melodye Pompa, who with her husband, John, runs the Caribbean Safety and Security Net (SSB 8104.0 kHz, 8:15 a.m. ET). Each morning, Melodye Pompa spends 5 to 15 minutes taking reports of crime against yachtsmen over high-frequency radio and discussing personal safety in the
Read the other stories in this package: Pirates in paradise: 'Lock it or lose it' Pirates of the Caribbean: hopped-up teenage punks
islands. The Pompas also issue lost-and-found bulletins to help family and friends back home locate yachts that haven't been heard from for a while.
"It started out as a way to let cruisers know what was going on — where they should lock up their dinghies because dinghies were going missing there," says Pompa. "But it's turned into this huge thing now."
The Pompas are told that anywhere from 1,000 to 2,000 cruisers listen in to these morning reports. They keep probably the most complete statistics available of crime against Caribbean cruisers, by island, anchorage and type of crime. They publish those statistics monthly at www.caribcruisers.com and keep six years of archived data, plus a list of common-sense security precautions, on the site. In October, Melodye Pampa was asked to prepare a statistical profile of crime against cruisers for a December meeting of tourism ministers hosted by the Organisation of Eastern Caribbean States.
The couple became volunteer crime-stoppers almost by accident. The net was started in 1996 by Frank Zachar aboard the yacht Vagabond Tiger. Bob Jones on Elixer and then Don Kline on Daisy D. followed as net control. Pompa says in August 1999 Kline asked her to fill in for him while Daisy D. holed up in Puerto Rican mangroves to escape a hurricane. She has been doing it since, every day except Christmas and the odd day off.
The Pompas, both retired — John from information management and Melodye from computer software sales and technical support — have been cruising on their Pearson 422, Second Millennium, since 1994. Melodye says they now limit their cruising to between Dominica in the north and Carriacou in the Grenadines, where they spend most of their time. "Home" to the Pompas is the boat in Carriacou, and the couple have become a part of that community. They organized a fund-raiser in August that raised $14,000 (XCD) — about $5,000 (U.S.) — that will buy school uniforms and books for 100 children, daily school lunches for 10 kids, and two community college scholarships.
She says if her statistics spur governments to crack down on crime, it benefits not only cruisers but people like themselves who live in the islands. For the Pompas, their crime watch is a neighborhood watch.
— Jim Flannery
Cruising couple bound for Newfoundland
A 'cruising' hydrofoil
Cruising couple finds freedom on the icw
Watch it on the web
Crime-busting boat buyer
Navy watches as cruising couple kidnapped
A new cruising rally for trawlers

redpajama_set_name: RedPajamaCommonCrawl


Brian Silva began working for iconic New England architect Geoffrey Cornish in 1983, building golf courses in the traditional way of the day. After a revelation concerning the essence of strategic golf he transitioned into golf course restoration, becoming one of the business's most respected talents at renovating historic Golden Age-era courses. His particular passion is for Seth Raynor, and Silva has been peerless in drawing attention to Raynor's work and helping clubs revive his lost architecture. Silva's acclaimed original courses include Black Creek in Tennessee, Black Rock, Waverly Oaks and Renaissance in Massachusetts, and he continues a busy renovation and consulting schedule.
Brian talks with Derek about his long career and everything else golf, including becoming a practice range ball banger, the disgusting happenings at Omni Amelia Island Plantation, being blown away reading a competing job proposal from Bob Cupp, the difficulty in getting high handicap players to "read" strategy, his epiphany at PGA West and the genius of Pete Dye, the regrettable Age of Engineering, the under-utilized potential of flat Florida golf sites, getting past the "skin" of a golf hole and into its skeleton, trends and followers in design and the joy of bringing Raynor to life at Black Creek Club.
Other than playing a handful of Mr. Silva's courses and knowing of his reputation for renovations and restorations, I didn't know much about him. But after listening to this episode, count me as a big fan. Mr. Silva's passion for his craft is evident; his enthusiasm is contagious; and his humor, modesty and self-effacing nature are infectious. Seems like the type of person you'd love to play a round of golf with, then sit back in the clubhouse for 2 or 3 hours with and listen to his stories and talk golf course design.


Ina here, who is having a great and awesome HOLIDAY!!!!! I know I am. I want to know what you guys did in the hoildays. Comment for what you guys did and I will reply the fabulous comment that you have posted. I am just writing this because I haven't been on my chromebook in a couple of days. So today I am blogging about the holidays that you guys did.
SO in my holidays I went to the movies and watch the Emoji Movie. It was the best movie I have ever watched in my whole entire life ( that was in Wednesday 4 October). On Tuesday 3 October I just stay home and sleep all day because I was really busy doing some Cross Country and you CANNOT believe. When I was doing Cross Country the place was really big and it was a really big rounded circle tiring and so I just did 1 lap. Also for the rest of my hoildays my mum said I have to come with her and she said something about a church and we are going to stay there for 3 days because I Mama past away on Friday 6 October. It was really sad and my cousins and I cried super hard also my Aunties, Uncles, Mama and Papa's.
That is all I can tell you guys and again comment what you are doing in the holidays.
Have a great and fantastic holiday.
I like your blog post about your holidays,can you please tell me more about your school holidays because I really want to know about it. I like how you said you watched the emoji movie.


While at Diversatech, I performed extensive research on laser engraving processes. One result of this research was color engraving. With absolutely no physical effects on the surface of the material (no roughness), I was able to create full-color marks on both Titanium and Stainless Steel. The research was performed on an Epilog Fusion M2 engraver, and involved an in-depth study of the chemical composition of different alloys of Titanium and Stainless Steel.
My favorite part of the entire process is that now, all of the Titanium Valve Covers built and shipped by Diversatech bear both the company's logo and an American flag (captioned "Proudly Made in America") in full-color.
Chemical source shutters developed at Diversatech.
Live satellite images of the earth via NOAA weather satellites.


In a nod to the 40th anniversary of the 1977 Foreign Corrupt Practices Act (FCPA) being signed into law, White Collar and Government Litigation Practice members Justin Danilewitz and Albert Moran co-authored this article for The Champion. The pair discuss the recent announcement by the U.S. Department of Justice regarding the new Foreign Corrupt Practices Act Corporate Enforcement Policy and its implications for companies and individuals.
"In the FCPA area and elsewhere, given the nature of the penalties, an ounce of prevention continues to be worth far more than a pound of cure," wrote the pair.


Thread: how to prepare for ivf with donor eggs?
Hello girls! Thanks to your comments I'm starting to change my attitude to the procedure. Now I feel more positive. I stopped thinking about relation with a baby from donor. Now I feel like I can move further. It's all thanks to you! I have some questions to you about the procedure. How you prepare to ivf with donor eggs? Is it the same as preparation to ivf with own eggs? How long it takes to prepare? I hope you'll share your experience! And also it would be great if you tell more about how you find donor, where did you have de ivf, how much you paid, etc. Let's have some chat!
First of all you should pay attention to your lifestyle. Take folic acid every day for at least 3 months before getting pregnant. This lowers the risk of some birth defects of the brain and spine of your child. Taking a pre-natal vitamin with folic acid is the best and easiest way to be sure you're getting enough. You should stop smoking and drinking alcohol. Stay away from second-hand smoke as well after you become pregnant. You should eat healthy. Everything that goes into your body can nourish your uterine environment—and can boost your embryo implantation success. Avoid eating fish that are high in mercury, like swordfish and mackerel. Consider limiting caffeine intake.
Speaking about the procedure itself. As you know I'm also in search and I'm new to this whole de ivf thing. But I read lots of info lately. So I'd like to share with you what I know. Your treatment cycle and the donation cycle of your donor must be carefully synchronized, so that your uterus is prepared and ready to accept the embryo created using your donor's eggs and your partner's sperm. To do this, your doctor may first need to 'switch off' your usual monthly period and ovulation cycle. This is referred to as 'down regulation,' and is achieved using a combination of the contraceptive pill and hormonal medications. At the same time, your egg donor begins her own cycle of treatment, firstly undergoing ovarian stimulation, followed by egg collection and fertilization. As you are using donor eggs and not your own eggs, there is no ovarian stimulation needed for your IVF cycle. Instead the main thing is to ensure your uterus is ready to accept the embryo. This is achieved through drugs protocol unique to you, which encourages your uterus to grow its lining ready for the embryo to implant. You'll undergo an ultrasound scan, where doctor measures the thickness of the lining to ensure it's at the optimum level for implantation. You will be given detailed instructions of any continuing medications you need to take post embryo transfer, to ensure your body is hormonally supported throughout this crucial early stage as the embryo implants and grows.
You are very wise to think ahead! Because the carrying mom needs a strong uterus and overall physique, to prepare I took and am taking prenatal vitamins and eating mostly whole foods. I'm also more careful with my sugar intake. I just cut back on sugar, and actually didn't miss it much as I was doing it for baby. Try to get at least 8 hours sleep, drink water, and walk for exercise, basically a pregnancy diet. The iron is especially important for the uterus and your increased blood production during pregnancy. The IVF clinic will make sure you have all you need as they will also watch your cycle to be sure to put in embryos at the proper time.
I wish you best of luck with your upcoming procedure! The shots and pills before your transfer are really not that bad, you just have to keep in mind what for you are doing it. Enjoy every bit of your journey. And know baby is all yours! No one will know it's a donor egg if you don't tell, so just go for it.
I'm happy to see your replies! I will consider all information I see here. I've already mentioned into my main thread that my feelings toward the procedure changed in a better way. Now I'm more into this. I still have some thoughts running into my mind. Despite them I feel more confident in using donor eggs. I found out about age limits and it kind of scared me. It turned out that each country has specific age limit for donor eggs recipient. This number varies from 45 to 50 years old. It suddenly crossed my mind that I have no time to waste! I will turn 45 soon. There is no time to think if this option is right for me or if I'm really ready for it. There is no time to waste on doubts and confusions. Now I'm fully on board! I talked to my hubby and he also thinks we should go for it. So I have a couple of questions for you! I really hope you will help me. What do you know about age limits for donor eggs recipients? I was looking through information on eggdonationfriends, but I've noticed that there is max age number missing in description about de of some countries. If you know what I mean. I will appreciate if you share your knowledge about this topic. And also I would like to know which criteria helped you to choose your clinic. I will be waiting for your answers! Again thank you so much for your comments.
I have conceived my 2 children through IVF. I think I can help you out. Well, I will explain this using my example. So I was married for 32 years without children. Then I decided to go to the hospital. My Ob told me that I had blocked fallopian tubes. Thus was caused by cysts. The cysts had grown to tremendous size so I had to have an operation. The operation was successful but it had an effect. My uterus was scarred. It had some issue that I could not give birth by myself. So my doctor suggested I go for an IVF. So I travelled to BTC, in Kiev to have the procedure. The clinic was affordable and had professionals at their top notch. My first trial was a success. After 2 years I then decided that I want another child. I still went to the same clinic and had my 2nd IVF. My children are now healthy and growing fast. So about the donor eggs I do not have much information for I used my own eggs. But you can go to BTC, I am sure all your questions will be answered.
Thank you so much for sharing your experience. My congratulations to you! Thank you so much for your reply. I really wanted to hear someone who has an experience. Do you know what age limit this clinic has? I'm almost 45 and I should say it's harder to find clinic. I also want to use anonymous donor. I know it's too early to think about this for me but I still don't know if I tell my child about it. I read many opinions about this issue. Someone says it's better to tell, someone decides to keep it in secret. I'm confused and not sure what is the right choice in this situation.
I have conceived my 2 children through IVF. I think I can help you out. Well, I will explain this using my example. So I was married for 32 years without children. Then I decided to go to the hospital. My Ob told me that I had blocked fallopian tubes. Thus was caused by cysts. The cysts had grown to tremendous size so I had to have an operation. The operation was successful but it had an effect. My uterus was scarred. It had some issue that I could not give birth by myself. So my doctor suggested I go for an IVF. So I travelled to BTC, in Kiev to have the procedure. The clinic was affordable and had professionals at their top notch. You cannot even imagine that there 2018 economic package is running out. My first trial was a success. After 2 years I then decided that I want another child. I still went to the same clinic and had my 2nd IVF. My children are now healthy and growing fast. So about the donor eggs I do not have much information for I used my own eggs. But you can go to BTC, I am sure all your questions will be answered.


text:
Q: gssproxy: apache httpd as nfs-client? centos7 When Apache httpd attempts to access a user directory automounted with sec=krb5p, and presumably other sec=krb options, gssproxy issues a failure message and the web server replies with 403 Forbidden. The debug option on gssproxy has not been sufficiently illuminating.
To rule out none RPCGSS issues, the 403 is not issued when a valid KRB5CC owned by uidNumber 48 (apache) is present in /tmp, and the web server will display the appropriate page. However, this is due to the behavior of rpc.gssd. gssproxy still issues the same failure message.
gssproxy: gp_rpc_execute: executing 6 (GSSX_ACQUIRE_CRED) for service "nfs-client", euid: 0, socket: (null)
gssproxy: gssproxy[639]: (OID: { 1 2 840 113554 1 2 2 }) Unspecified GSS failure.  Minor code may provide more information, No credentials cache found

# cat /etc/gssproxy/gssproxy.conf
[gssproxy]

[service/HTTP]
  mechs = krb5
  cred_store = keytab:/etc/gssproxy/http.keytab
  cred_store = ccache:/var/lib/gssproxy/clients/krb5cc_%U
  euid = 48

[service/nfs-server]
  mechs = krb5
  socket = /run/gssproxy.sock
  cred_store = keytab:/etc/krb5.keytab
  trusted = yes
  kernel_nfsd = yes
  euid = 0

[service/nfs-client]
  mechs = krb5
  cred_store = keytab:/etc/krb5.keytab
  cred_store = ccache:FILE:/var/lib/gssproxy/clients/krb5cc_%U
  cred_store = client_keytab:/var/lib/gssproxy/clients/%U.keytab
  cred_usage = initiate
  allow_any_uid = yes
  trusted = yes
  euid = 0

# klist -ke /var/lib/gssproxy/clients/$(id -u apache).keytab
Keytab name: FILE:/var/lib/gssproxy/clients/48.keytab
KVNO Principal
---- --------------------------------------------------------------------------
   2 apache/www.example.com@EXAMPLE.COM (aes256-cts-hmac-sha1-96)
   2 apache/www.example.com@EXAMPLE.COM (aes128-cts-hmac-sha1-96)
   2 apache/www.example.com@EXAMPLE.COM (camellia256-cts-cmac)
   2 apache/www.example.com@EXAMPLE.COM (camellia128-cts-cmac)

# cat /etc/systemd/system/gssproxy.service.d/override.conf
[Service]
ExecStart=
ExecStart=/usr/sbin/gssproxy -D --debug

A: I used strace to see that gssproxy was looking for the keytab in /var/kerberos/krb5/user/48/client.keytab.  I also needed to set the selinux context:
chcon -t krb5_keytab_t /var/kerberos/krb5/user/48/client.keytab
ls -lZ /var/kerberos/krb5/user/48/client.keytab
-r--------. apache apache unconfined_u:object_r:krb5_keytab_t:s0 /var/kerberos/krb5/user/48/client.keytab

It appears that the HTTP stanza is taking precedence over the nfs-client stanza for UID 48.

redpajama_set_name: RedPajamaStackExchange


Description: Watch & Enjoy Winner Movie Pre Release Event. Starring Sai Dharam Tej, Rakulpreet And Jagapathi Babu. Movie Directed By Gopichand Malineni & Music Composed By SS Thaman and Movie Produced by Nallamalupu Bujji & Tagore Madhu Under The Banner of Sri Lakshminarasimha Productions. Click here to Share on Facebook- http://bit.ly/2mgP7t7 Download Nenu Local Official Mobile app on Google play- http://bit.ly/2kmE5pJ Buy Now on iTunes- http://apple.co/2lZVqFu Audio availale on; Saavn- http://bit.ly/2lZNJix Wynk- http://bit.ly/2m3eWxu Hungama- http://bit.ly/2kPDgkF Movie : Winner Starring : Sai Dharam Tej, Rakul Preet & Jagapathi Babu Director : Gopichand Malineni Music Director : SS Thaman Producer : Nallamalupu Bujji & Tagore Madhu Banner : Sri Lakshminarasimha Productions Lyrics : Ramajogaiah Sastry, Anantha Sriram, Bhaskara Bhatla Singers : Suma Kanakal, Anurag Kulakarni, Yazin Nizar, Sanjana Kalamanjie, Deepak, Christopher Stanley, Saicharan, MLR Karthikeyan, Naveen Madhavan, Srikrishna, Aditya Iyengar, Sarat Santhosh, Hymath, Arun Koundinya, Nakash Aziz, Sharmila, Anthara. Music Lable : Aditya Music ----------------------------------------------------------------------------------------- Enjoy and stay connected with us!! ►Subscribe us on Youtube: http://bit.ly/adityamusic ►Like us: http://www.facebook.com/adityamusic ►Follow us: http://www.twitter.com/adityamusic ►Circle us: https://plus.google.com/+adityamusic SUBSCRIBE Aditya Music Channels for unlimited entertainment: ►For New Movies in HD: http://www.youtube.com/Adityamovies ►For Songs with Lyrics: https://www.youtube.com/AdityaMusicNM... ►For Devotional Songs: http://www.youtube.com/AdityaDevotional ►For Kids Educational: http://www.youtube.com/AdityaKids →"మా పాట మీ నోట" Telugu Lyrical Songs - http://bit.ly/1B2EcJG →Latest Tollywood Lyric Video Songs - http://bit.ly/1Km97mg →Ever Green Classics - https://goo.gl/1fZEDy →Popular Jukeboxes - https://goo.gl/LNvAIo →Telugu Songs with Lyrics - https://goo.gl/7ZmgWT © 2017 Aditya Music India Pvt. Ltd.


text:
Ставропо́льская возвы́шенность — возвышенность в Среднем Предкавказье, в центральной части Предкавказской равнины. Высшая точка — гора Стрижамент (831,8 м). Административно возвышенность расположена в пределах Ставропольского края, а также частично в восточной части Краснодарского, крайнем западе Республики Калмыкии.

Орография
Возвышенность сменяется Терско-Кумской низменностью на востоке, Кубано-Приазовской низменностью на западе и Манычской впадиной на севере, а на юге резко обрывается к долинам рек Суркуль и Кубань. Преобладают высоты от 300 до 600 метров. Возвышенность расчленена широкими долинами рек и балками на платообразные останцовые массивы и гряды. В её рельефе выделяют Центральную гряду, Бешпагирские высоты, Южную гряду (здесь находится высочайшая точка возвышенности — 831,8 метров — гора Стрижамент) и Прикалаусские высоты. В западной части расположена Сенгилеевская котловина, в настоящее время заполненная Сенгилеевским водохранилищем. К югу от возвышенности начинаются предгорья Большого Кавказа.

Геология
Возвышенность преимущественно сложена глинами, песчаниками и известняками, строматолитами, в восточной части — суглинками.

Климат
Зимы довольно мягкие (от −4 до −6°С), лето жаркое (22—25°С), весна короткая, и сравнительно длинная осень. Среднегодовое количество осадков колеблется от 200—300 мм на востоке до 600 мм на западе. Регион часто подвержен бурям и продувается ветрами типа фёнов.

Гидрография
На возвышенности берут начало реки Егорлык, Калаус, Томузловка. В западной части проходит Азово-Каспийский водораздел.

Почвы
В почвенном покрове преобладают чернозёмы и глинозёмы.

Растительность
Континентальный климат довольно сухой и, следовательно, преобладающим растительным покровом является полупустынный, переходящий в более возвышенных и менее засушливых западных частях в лесостепь с широколиственными лесами. Большей частью возвышенность и её подступы активно возделываются и распаханы для сельхозугодий, вода к которым подаётся из Большого Ставропольского канала, а также из рек Кубань и Егорлык.

Население
В наиболее высокой западной части возвышенности расположен краевой центр — город Ставрополь — давший название возвышенности. В её пределах также расположены города Михайловск, Изобильный, Светлоград, Благодарный.

Примечания

Рельеф Ставропольского края
Возвышенности России
Русская равнина
Предкавказье

redpajama_set_name: RedPajamaWikipedia


Hold on to your hats, the April promotional card for Kaijudo is crazy! Ravenous Detrivore is a 6 casting cost green/black card with the ability Munch. This power not only allows you to place a card from your discard pile and put it at the bottom of your deck, but he also takes on the power of that creature. If that power is 6000 or greater he increases his breaker ability! We are given these cards at the same time we get the Friday Night Magic promos, and we will give them to players competing in the weekly tournament for Kaijudo. Our tournaments are being held every Saturday at 11:00AM.
This Saturday, April 5th, 2014, is International Table Top Day. This is a day were free promotional items are given out for classic table top games such as Rampage and Tokyo. Play Kaijudo and then stay for Table Top. We have a huge demo section filled with games for use.


text:
The Annual Biography and Obituary for the Year ..., Volumen 4
the manner in which it was prosecuted. It will naturally be concluded that he opposed the administration of the late Mr. Pitt with a considerable degree of zeal and uniformity. But let it be recollected, that on the occasion alluded to, he but obeyed the instructions of his constituents, either expressed or implied: for the livery of London have always exhibited a marked antipathy to continental connections.
In fine, we no sooner find the alderman fairly seated in parliament, 'than he took an active part in the debate that ensued in consequence of a motion of Mr. Fox *, against the premier of that day, for presuming to meddle with the public purse, in express opposition to the rights and privileges of the House of Commons. Mr. Combe, in obedience to the voice of the livery, assembled that day in common-hall, who had enjoined him to vote a censure on His Majesty's Ministers, for lavishing the public treasure without the consent of Parliament, not only supported, but also seconded the motion. The member for London commenced a maiden speech of some length, by expressing his pleasure, in obeying the voice of his constituents, as expressed that very forenoon, at a numerous and respectable meeting. They had almost unanimously disapproved of the conduct of His Majesty's Ministers on the present occasion; and it was with peculiar satisfaction he now. obeyed their commands, his duties as a representative being in strict unison with his own opinions. " After what had been advanced by his Right Hon. friend (Mr. Fox), he would not say a word upon the subject in a constitutional point of view. As the representative of the first commercial city in the world, he was well acquainted with the mischief produced by the money sent to the Emperor. The discounting of the bills drawn for the purpose of remitting money to
* "That His Majesty's Ministers having authorised and directed, at different times, without the consent, and during the sitting of Parliament, the issue of various sums of money for the service of his Imperial Majesty, and also for the service of the army under the Prince of Condé, have acted contrary to their duty, and 10 the trust reposed in em, and have thereby violated the constitutional privileges of this House."
the Imperial troops had swallowed up so much of the wealth of the Bank, as to compel that great body to narrow their discounts; and the British merchants were made to suffer, that the German troops might be supplied. The remittances to the allied armies on the continent had, in fact, been a great cause of the alarming scarcity of money last year, and of most of the embarrassments which had been experienced in the commercial world."
He next adverted " to the professions which had been so recently made by members of Parliament, of love and respect for the constitution, and of regard and deference for the sentiments of their constituents, which he hoped had not already evaporated; on the contrary, he trusted that gentlemen would, on the present evening, give a proof of the contrary. He professed to be attached personally to no man, nor to have any prejudice against any of the members of administration. He voted with Mr. Fox, as a friend to human happiness, which was best secured by political liberty; and this evening he came down, to use the phrase of the Right Hon. Gentleman, impregnated with the sense of his constituents, which was this day so fairly and decidedly given by the Commonhall."
On the 19th of May, 1797, the alderman was pitched upon by Opposition, once more to instigate the immediate removal of the servants of the crown, Accordingly, having noticed all the principał events of the war, and dwelt on the most disastrous epochs of the history of that period, Mr. Combe contrasted the promises of the Cabinet with their actual conduct, and insisted on the consequent disappointment of the public. He concluded a harangue, which was listened to with great attention by both sides of the house, with the following motion : " That an humble address be presented to His Majesty, beseeching him to dismiss from his presence and councils his present ministers, as the most likely means to obtain a speedy and permanent peace." Sir William Milner, Bart., one of the representatives for the city of York, seconded the
motion, which was lost, however, on a division, by a majority of 183.
We find the member for London, who appears to have been the only one of the four who would pledge himself explicitly to obey the instructions of his constituents, soon after supporting Mr. now Lord Grey, in his celebrated motion for a reform in Parliament. Here again, a failure in point of numbers, rather than of arguments, ensued, and that measure has never since been carried into effect: nor is it now, we believe, an object of particular desire on the part of the nobleman then so eager for its success.
In 1800, being then invested with the city regalia, the subject of the present memoir introduced a petition from " His Majesty's most loyal and dutiful subjects, the lord mayor, aldermen, and livery of the city of London, assembled at the Guildhall of the said city, against the continuance of the present war." Instead of being supported by his colleagues on this occasion, the application was ridiculed by some, and disavowed by others, as not expressing the sentiments of their constituents at large.
In 1803, he opposed the principle of the income tax as odious, vexatious, and unequal. Here again he obeyed the injunctions of the livery; and yet two of his colleagues voted in favour of the new impost, in direct opposition to the orders received by them in the Common-hall.
But Mr: Alderman Combe, although frequently, was not uniformly in opposition to all the measures of the cabinet of that day. On the contrary, at a time of great difficulty and danger, he warmly supported the " General Defence Act," and boldly declared, that not only those actually under arms, " but every man in the kingdom ought to go forth, in hostile array, against the enemies of their country, when called upon by the exercise of His Majesty's acknowledged prerogative. There could be no exemption but on the ground of express inability. The citizens of the metropolis," added he," are not only ready, but anxious to learn, how they can come forward with most effect. If there were any apprehension, it
could arise only from the probability of embarrassment, bý the crowds that would rush forth to accomplish a sacred duty. In fine, in every ward, parish, and street' of London, the people are only waiting with impatience until His Majesty shall be pleased to point out the means of organizing their courage."
On another occasion (March 19. 1804) Mr. Alderman Combe stated, "that the volunteer force, furnished in and about the metropolis, then amounted to about 2000 men. There was not a single individual of these, who, in case of an invasion, did not consider himself liable to be placed under the command of a general officer, and marched to any part of the kingdom. No one could presume to doubt of the well-known loyalty and zeal of the city of London, because, being expressly exempt by their charter from those military duties to which the rest of England is liable, they had no manner of occasion to seek for refuge from the ballot. It was accordingly evident, that the offer of their services, their zeal, and their energy, could alone originate in a pure and patriotic spirit."
When Mr. Pitt came a second time into place, Mr. Combe divided against his " Additional Force bill," and founded his objections both on constitutional and political grounds. In the Spring of 1805 he joined Mr. Grey, in his motion for papers, with a view to censure Ministers relative to their conduct towards Spain. He also supported Mr. Brand in his motion for the removal of the Cabinet, and voted with Mr. Grey (then become Lord Howick), against the address to the Crown.
There were two occasions, and we believe two only, about this period, on which Mr. Combe happened not to vote in a minority; on the former of these, he acted in direct unison with all the other city representatives, who declared themselves decidedly of opinion, that the supposed malversation of Mr. Dundas (afterwards Lord Melville), while treasurer of the navy, demanded immediate investigation; and they accordingly contributed to form the celebrated majority of one. The other included a subject of much personal delicacy, and he must have made a great sacrifice to his private feelings, by his vote on that day. We now allude to the parliamentary accusation again his Royal Highness the Duke of York, during the first time he acted as commander-in-chief. On this occasion, notwithstanding a certain degree of intercourse, and even intimacy, with this Prince of the Blood, yet Mr. Combe, listening to the voice of his constituents only, joined in the proposition for an enquiry, and was the only one of the four members who obtained the thanks of the Common-hall upon that occasion.
It now remains to mention one peculiarity respecting the subject of this memoir. After the death of his friend Mr. Sawbridge, he began to be considered the best whist player in London. Having at length been admitted a member of Brookes's, he there, of course, associated with some of the first personages in the kingdom, and was not unfrequently accus, tomed, at other times and places, to try his skill with one of the Royal Dukes. On these occasions, the Alderman is allowed to have displayed a wonderful degree of recollection and selfcommand; and this was not a little aided by his temperance, and even abstemiousness, previously to any grand match. We have yet to learn that he ever suffered this attachment to interfere with his duties, either public or domestic; and there is reason to suppose, that on the whole, his fortune did not suffer any diminution by an occasional love of play. It may be questioned, however, whether late hours, and long and intense application, did not prove prejudicial to his health, The truth is, that he was seized with a paralytic affection, exactly in the same manner, and perhaps from expressly the same cause, as the late Alderman Sawbridge; and, like him, experienced a long and lingering illness for some years before his death.
But although his lower limbs were debilitated, yet the vigour of his mind remained almost wholly unimpaired until the summer of 1817, when he was greatly affected by an event of a public nature. This was the resolution of a Common Hall, which was very thinly attended, purporting that this member should be invited to resign his seat in