Stella Restaurant: restaurante con vista al jardín, y servicio de desayuno, comida y cena. Ofrece un menú infantil. Requiere reservación. Abre todos los días.
The Bar & Conservatory: bar con vista al jardín, y servicio de comida, cena y platillos sencillos. Se puede comer al aire libre (si el clima lo permite). Abre todos los días.
Outstanding Hotel, A Must Stay.
Booked this beautiful hotel for my partner birthday. It's luxurious throughout, the staff were lovely. Highly recommended this hotel if you want to be spoilt. Relax and enjoy the beautiful surroundings. Fantastic, Warm, Friendly Staff. Best hotel I've ever stopped in.
Fantastic hotel with very efficient staff. We stayed two nights including New Year's Eve. The biggest disappointment was the NYE meal which was overpriced at 65.00 each. Food selection was poor and portions tiny. Long wait for food. Heard the same complaints from other guests. We also waited 20 minutes for breakfast. It was such a shame as the hotel and staff were faultless in every other area. We were told the manager would contact us but that was 5 days ago.
Had a wonderful stay, the staff and service was excellent from start to finish. Lovely food in the conservatory in the evening and fabulous breakfast. A lovely added touch was a complimentary tray of goodies left for us in our room for my husbands birthday. A beautiful hotel.


text:
\section{Introduction}
The von K\'arm\'an flows generated in the gap between counter-rotating impellers has been considered by several groups as a possible candidate~\cite{Maryland,Wisconsin,VKSPoF} in the search for a laboratory demonstration of a homogeneous fluid dynamo that would be less constrained than the Riga and Karlsruhe designs~\cite{Riga,Karlsruhe}. In these experiments, liquid sodium is often used because its electrical conductivity is high (half that of copper, at $120^{\circ}$C), while its density remains low, of the order of that for water. Its magnetic diffusivity, as for all metals,  is many orders of magnitude larger than its hydrodynamic viscosity. The flow Reynolds number needs to be very large in order for non-linearities to develop in the magnetic induction. As a consequence, the hydrodynamic flow is very turbulent, and many questions arise concerning the influence of turbulence on the bifurcation threshold and the dynamics in an eventual saturated regime.

This problem is very complex, and many studies so far have focused on the dynamo capacity of the average flow engineered in the von K\'arm\'an (VK) geometry. Here, `average' has the meaning of `time-average'. A time-averaged flow field $\langle {\bf U}\rangle ({\bf r})$ is derived from measurements in water prototypes (for convenience and because velocimetry methods are scarce in opaque, high temperature flows of
 liquid metals~\cite{DOPNataf,DOPGerbeth}) as:
\begin{equation}
\langle {\bf U} \rangle ({\bf r}) = \frac{1}{T} \int_0^{T} {\bf U}({\bf r}, t) dt \ ,
\label{eqMoy}
\end{equation}
where $T$ is a time much longer than the one characteristic of the forcing of the flow (estimated, for instance, as the period of rotation of the driving impellers). This stationary flow profile --  no longer a solution of the Navier-Stokes equation -- is then usually inserted into a kinematic numerical solver, in which the induction equation
\begin{equation}
\partial_t {\bf B} = \nabla \times \left( \langle {\bf U} \rangle \times {\bf B} \right)  + \lambda \Delta {\bf B} \ ,
\label{eqB}
\end{equation}
($\lambda$ is the magnetic diffusivity) is solved with the velocity field kept constant in time~\cite{Marie,ForestKinematic,Ravelet}. These studies have shown the possibility of dynamo action in the average VK flows, and the underlying induction processes have been measured in sodium and Gallium flows~\cite{VKSPoF,bourgoinvolk}  and analyzed in details~\cite{bourgoinPoF,MarieThesis,BourgoinThesis}. It showed that the helicity and differential rotation present in the von K\'arm\'an mean flow cooperate to generate a self-sustained dynamo.

The existence of a kinematic dynamo threshold for the VK flows, together with the possibility to bring its value within experimental reach (in terms of power requirements) has motivated the sodium experiments in Maryland, Cadarache and Wisconsin~(\cite{VKSGydro} and references therein). However, it has also been recognized early~\cite{MordantGlobal} that VK flows at high Reynolds numbers have strong fluctuations. As a result the instantaneous mean flow structure can differ significantly from the time-averaged flow. This has motivated investigations
regarding the influence of noise on the dynamo bifurcation.
For instance, it has been proposed that the VK flow may lead to an intermittent dynamo~\cite{LathropOnOff,Wisconsin,Leprovost}:  burst of dynamo activity would occur, triggered by transient flow structures that are most efficient at generating magnetic induction.

Induction measurements in the presence of an externally applied field have been made in the VKS experiment~\cite{VKSPoF}. They have demonstrated the existence of fluctuations in the magnetic induction due to small scale turbulence and also generated from the instationarity  of the large scales. For example, it has been observed that the local fluctuations of induction measured during a time interval $\tau$ increase  logarithmically with $\tau$~\cite{VKSPoF}. This finding can be linked to the existence of a $1/f$ scaling in the low frequency domain of the magnetic induction spectrum, a feature that has been also observed in numerical models~\cite{PontyPRL1} and in the dynamo regime of the Karlsruhe experiment~\cite{KarlsruheRecent}.

The purpose of this article is to explore further the above ideas. We relate the fluctuations in time of magnetic induction to large scale fluctuations in the geometry of VK flows. We use a VK flow of liquid Gallium, and we study the magnetic induction in the presence of an externally applied field. Besides being relatively easy to handle in the laboratory, the magnetic Reynolds number in Gallium flows reaches values of order 1: induction effects are measurable and the non-linearities are not yet strong. The amplitude of the induced field is often an order of magnitude smaller than the amplitude of the applied field, and, in the quasi-static limit~\cite{bourgoinPoF}, the induction equation (\ref{eqB}) is reduced to $\nabla \times \left( \langle {\bf U} \rangle  \times {\bf B}_0 \right) + \lambda \Delta {\bf B} = 0$, with ${\bf B}_0$ the applied field. When it is uniform in space, the induced field solves $\lambda \Delta {\bf B} = - ({\bf B}_0 \cdot \nabla) \langle {\bf U} \rangle$ so that it is directly related to the velocity gradients in the flow (although the solution is not local;  the overall topology of the velocity gradients and the boundary conditions do enter in the solution of this Poisson equation).

The induction measurements are made using a new probe made of a line of magnetic field sensors. It samples simultaneously one component of the magnetic field at several location within the flow. The paper is organized as follows: in the next section, we describe the experimental set-up and we characterize our multi-probe magnetic measurements. The results are detailed in section III and their implications regarding dynamo action in VK flows are discussed in  section IV.

\section{Set-up and measurements}

\label{exp_setup}
\subsection{Flow.}
Our experiments are carried out in the setup sketched in Fig.\ref{setup}. The flow is produced by the rotation of one or two disks inside a stainless steel cylindrical vessel filled with liquid Gallium. The cylinder radius  $R$ is 97~mm and its length is 323~mm. The disks have a diameter equal to 165~mm and are fitted a set of 8 blades  with height $10$~mm. They are separated by a distance $H =203$~mm. The disks are driven by two 11~kW AC-motors  which provide a constant rotation rate in the interval $\Omega \in [0.5, 25]$~Hz with a stability of about 0.1\%.  The system  is cooled by a set of coils located behind the driving disks; the experiments are made with the flow kept at a temperature in an interval between $42^{\circ}$C and $48^{\circ}$C. The fluid is liquid Gallium  (density $\rho = 6.09 \times 10^{3} \; {\rm kg} \; {\rm m}^{-3}$) whose electrical conductivity is
 $\sigma = 3.68 \times 10^{6} \; {\rm ohm}^{-1} \; {\rm m}^{-1}$. Its kinematic viscosity is  $\nu = 3.1 \times 10^{-7} \; {\rm m}^{2} \; {\rm s}^{-1}$.  The integral kinematic and magnetic Reynolds numbers of the flow are defined as ${\rm Re} = {2\pi R^{2}\Omega}/{\nu}$ and ${\rm R_m} = 2\pi \mu_{0}\sigma R^{2}\Omega$. Values of ${\rm R_m}$ up to $5$ are achieved, with corresponding ${\rm Re}$ in excess of $10^6$.

\subsection{Induction measurements.}
Two sets of coils (see Fig. \ref{setup}) are used to apply an external magnetic field ${\bf B}_0$, either parallel or perpendicular to the axis of the cylinder. The locations of the coils is such that the configuration is close, but not strictly equal, to a Helmholtz geometry. Variations of applied field intensity over the flow volume are of the order of 18\% of the mean, for axial or transverse applied fields. Its magnitude $B_0$ is less than 100~G, so that the interaction parameter,
\begin{center}
 $N = \sigma B_0^{2} L / \rho U = \sigma B_0^{2} 2R / \rho 2\pi R \Omega \sim 10^{-3}$ \ ,
\end{center}
is quite small. One can safely neglect the back-reaction of the Lorentz forces on the velocity field.

\begin{figure}[htb]
\centerline{\includegraphics[width=14cm]{aFig1.eps}}
\caption{Set-up : (a) schematics of the von K\'arm\'an mean (time-averaged) flow geometry for counter rotating disks at equal rate $\Omega$. The rotation is opposite in each  half of the cylinder, leading to a strong differential rotation and the recirculation loops in the flow create a stagnation point: the poloidal flow converges in the mid-plane and is drawn towards the disks on either side. (b) experimental arrangement: coils and magnetic measurement probe.}
\label{setup}
\end{figure}

Magnetic induction measurements are performed using a multi-sensor probe. Eight Hall sensors form a linear array which can be inserted inside the flow to yield  simultaneous measurements of the magnetic field along a line, {\it i.e.} measurements of magnetic {\it induction profiles}.  In the experiment, the probe array is inserted radially into the flow, in the mid-plane between the driving disks. The magnetic field is sampled at 8 locations between 1.5 and 8.5~cm from the rotation axis. The spacing between the Hall sensors is equal to 1~cm, equal to the overall diameter of the probe --  small compared to magnetic diffusive scale in the Gallium flow ($\ell_M \sim 2R/{\rm R_m}^{3/4} \geq 6$~cm).
According to the orientation of the probe, one obtains a radial profile of one component of the magnetic field,   $B_x(r_i,t)$ or $B_z(r_i,t)$ (for $i=1...8$) --- the axis are shown in Fig.~\ref{setup}. The Hall sensors are single axis elements from Sentron ($1$SA-$1$M), with a sensitivity of $0.03$ V$/$G and a frequency range from DC to $10$~kHz. We have calibrated these probes by comparison with a temperature compensated Hall probe connected to a Bell  FW-9953 gaussmeter. Their temperature dependence is small, of the order of $0.01$ G$/$K in the temperature range of interest {\it i.e.} between $40$ and $50^{\circ}$C. In typical measurements, the signals from the 8 sensors are  recorded for durations between $150$ and $480$~seconds, using a National Instrument PXI-4472 digitizer at a rate of $1000$~Hz with a 23 bits resolution.\\

\begin{figure}[hbt]
\centerline{\includegraphics[width=7cm]{aFig2.eps}}
\caption{Spectrum obtained with one Hall sensor, compared to a measurement made using a calibrated Bell gaussmeter. Flow driven by the rotation of a single disk, at $\Omega = 10$~Hz. The main peak is at $8.5$~Hz because the flow rotation rate is lower that that of the driving disk. }
\label{spectre1}
\end{figure}

We compare in Fig.~\ref{spectre1} a typical frequency spectrum computed using a time series from a single sensor, compared to the equivalent measurement made with the  Bell gaussmeter. In this case, the flow is set into motion by the rotation of only one of the driving disk, as in ref.~\cite{VKSalpha}; this choice is made in order to have a steady flow with little large scale fluctuations. The two curves are in excellent agreement. The dynamical range spans 80~dB. Our in-house magnetic line array has thus characteristics that are equivalent to those of the commercial single probe.

\section{Results}
\subsection{Average induction profiles}
We present here the analysis of mean induction effects which will be useful for our discussion of the fluctuations -- the reader is also referred to~\cite{bourgoinvolk}.

We label ${\bf B}_0$ the applied field and ${\bf B}({\bf r}, t)$ the field induced by the flow motion. We write the total magnetic field as ${\bf B}_0 + \langle {\bf B} \rangle + {\bf b}$, where $\langle {\bf B} \rangle $ is the time average of the induced field, and ${\bf b}$ the fluctuating part ($\langle {\bf b} \rangle = 0)$. By definition, the $k$-th component of time-averaged induced field at location ${\mathbf r}_j$ is
\begin{equation}
\langle B_k(r_j) \rangle = \frac{1}{T} \int_0^{T} dt \, B_k(r_j, t) \ .
\end{equation}
In practice we have chosen $T \sim 100 \; \Omega^{-1}$, where $\Omega^{-1}$ is the period of rotation of the driving disks.

\begin{figure}[hbt]
\centerline{\includegraphics[width=14cm]{aFig3.eps}}
\caption{(Top) Time-averaged induction profile $\langle B_\theta \rangle(r_j)$ for an axial applied field $B_{0,z}$. (left): measurements for ${\rm R_m} = 1, 2, 3, 4$, top to bottom (the symbols are the measurements and the solid line is the result of the numerical simulation based on the time-averaged flow). (right): schematics of the Omega effect responsible for the induction.\\
(Bottom): corresponding figures for $\langle B_z \rangle(r_j)$ measurements in the case of a transverse applied field $B_{0,x}$. In this case the induction is due to the stretching and compression of the field lines by the axial flow. }
\label{meanprofiles}
\end{figure}

In Fig.~3(a,b) we show the induction profiles $\langle B_\theta \rangle(r_j)$ and $\langle B_z \rangle(r_j)$ measured when an external field ${\bf B}_0 = B_{0} \hat{z}$ is applied, directed along the axis of the cylinder. As detailed in previous studies (e.g.~\cite{bourgoinvolk}), the azimuthal component  $\langle B_\theta \rangle$ is mainly generated by the counter rotation induced by the driving impellers on each side of the mid-plane, {\it via} the Omega effect~\cite{Moffat}
\begin{equation}
\lambda (\Delta \langle {\bf B} \rangle)_\theta = - B_{0,z} \partial_z \langle U_\theta \rangle \ .
\end{equation}
On the other hand, when one probes the induced field along the axis, the main effect is due to the axial stretching cause by the motion of the fluid towards each driving disks (the stretching component of the stagnation point in the mid plane).
\begin{equation}
\lambda \Delta \langle B_z \rangle = - B_{0,z} \partial_z \langle U_z \rangle \ .
\end{equation}
These mechanisms are sketched in figure~3. We stress that these profiles are obtained from simultaneous sampling in space of the magnetic field, and not from a series of independant measurements in which a single probe is successively located at a set of radial positions, as previously reported~\cite{VKSPoF,bourgoinvolk}.

We then compare the measurements to a numerical solution of the stationary induction equation:
\begin{equation}
0 = \nabla \times \left( \langle {\bf U} \rangle \times ( {\bf B}_0 + \langle {\bf B} \rangle ) \right) + \lambda \Delta \langle {\bf B} \rangle  \ .
\label{eqIndSta}
\end{equation}
In the numerical computation, the time-averaged velocity field is taken from experimental measurements~\cite{Marie} and the induction equation is solved using the iterative method described in detail in~\cite{bourgoinPoF}  (the scheme is based on finite difference computations, and thus allows for the implementation of realistic  electromagnetic boundary conditions). Because ${\rm R_m}$ remains small (less than 5), we have found that in each case it was sufficient to compute the induction up to order 3 in ${\rm R_m}$. In Fig.~3, the profiles obtained numerically are shown as solid lines. One observes an excellent agreement with the experimental measurements.
It indicates that the mean induction is very well accounted for by the time-averaged flow --- equation~(\ref{eqIndSta}).

Using all combinations for the directions of the applied and measured induced magnetic fields, we have observed that the induction is dominated by two main mechanisms: the differential rotation generated by the counter rotating disks (the toroidal part of the flow) and the existence of a stagnation point in the mid plane (the poloidal component).  For an applied field parallel to the rotation $z$-axis (case in Fig.~3), the toroidal velocity gradients induce a toroidal magnetic field (the Omega effect) and the poloidal velocity gradients generate a stretching of the applied field lines. When the field is applied transverse to the rotation axis (e.g. along the $x$-axis) the poloidal flow produce a compression of the applied field lines while the toroidal flow generates a $z$-component associated to the connection of the magnetic field lines induced along the $y$-axis on each side of the mid plane. This effect is quite sensitive to the electromagnetic boundary conditions; we have called it the BC-effect~\cite{bourgoinPoF}.

Regarding the mean (time-averaged) value of the magnetic induction, our main finding is  that the average induction coincides with the induction predicted from the average flow --- at least for the magnetic Reynolds numbers reached in this Gallium experiment. One has
\begin{equation}
\langle {\bf B} \rangle = {\rm induction \; from \; } \langle {\bf U} \rangle \ ,
\end{equation}
{\it i.e.}, the mean induced field effectively solves $ \nabla \times \left( \langle {\bf U} \rangle \times {\bf B}_0 ) \right) + \lambda \Delta \langle {\bf B} \rangle = 0$. We will report elsewhere a detailed analysis of the induction effects due to the turbulent small scale  fluctuations~\cite{VolkPerm}; its main finding is to confirm the above statement: the small scale turbulent fluctuations do not contribute to the mean induction.

\subsection{Fluctuations}
\subsubsection{General considerations}
As pointed out in the introduction, due to the very small value of the Prandtl number,  the flow is fully turbulent. The Reynolds number is larger than $10^6$, even for the relatively moderate values of the magnetic Reynolds number reached here. The local velocity fluctuations reach 35\% of the mean speed, and so do the induced fields, as shown in figure 4(a,b). The fluctuations are large and occur over a very broad range of time scales. The fastest fluctuations are associated with the shearing of the applied field by the turbulent small scale motion~\cite{Odier98}.  Komogorov's scaling for the inertial range of motions together with the use of Taylor's hypothesis predict an $f^{-11/3}$ for frequencies larger than that, $\Omega$, of the forcing. This is due to the fact that  in our experiment ${\rm R_m}$ is of order one, so that the magnetic dissipation scale $\ell_M$ is of the order of the flow size. Our measurements -- figure 4(c) -- show a steeper slope, of the order of $-4.6$ for driving disks fitted with blades. The Kolmogorov prediction $-11/3$ was observed in the flow generated by flat rugose disks~\cite{Odier98}.  The slope of the spectra in the high-frequency (dissipative) region does not depend upon which component is being probed, nor on the rotation rate of the disks.

Another observation is that the magnetic induction also fluctuates in a broad range of long time scales, as indicated by the behavior of the power spectra for frequencies lower than the disks rotation rate $\Omega$ -- Fig.~4(c).  In addition, it is clear  in figure~4(c) that the lower end of the frequency spectra does depend on which induction mechanism is at work. In the case of an axial applied field, the fluctuations in the toroidal  component of the induction are related to fluctuations in the differential rotation. The low frequency part of the spectrum is close to an $f^{-0.5}$ behavior. The fluctuations of the induced field in the direction of a transverse applied field are linked to the dynamics of the stagnation point in the mid plane. In this case the low frequency part of the spectrum has stronger fluctuations (the spectrum is close to a $f^{-1.2}$ behavior). The fluctuations of induction are associated to fluctuations in the position of the stagnation point. Concerning this slow dynamics, we have also varied the disks rotation rate between 5~Hz and 20~Hz without detecting any noticeable change in the above features; the spectra as in figure~4(c) collapse when rescaled by the rotation rate and the fields $rms$ amplitude.

\begin{figure}[hb]
\centerline{\includegraphics[width=10cm]{aFig4.eps}}
\caption{Fluctuations for local measurements. Counter-rotation of the disks at $\Omega = 10$~Hz. (a) $B_x$ induced component for an applied axial field $B_{0,z}$; (b) $B_x$ induced component for an applied transverse field $B_{0,x}$, (c) Corresponding time spectra (black line : signal in (b); blue line : signal in (a)). The curves have been shifted vertically for clarity; (d) Power spectral density of the pressure recorded at the flow wall in the mid-plane.   }
\label{localfluct}
\end{figure}

The slow dynamics in the induction traces back to the evolution of the hydrodynamic flow. This is evidenced by measurements of pressure fluctuations at the wall; one observes a $1/f$ behavior  in the same range of frequencies where the magnetic fields shows a long-time dynamics -- figure~4(d). However, the magnetic measurement is quite sensitive because is probes the velocity gradients selectively. The poloidal and toroidal components are independantly probed by chosing the direction of the applied field and the particular component of the induced field under inspection.

\subsubsection{Profile fluctuations}
We analyse below the fluctuations of induction `profiles' which we define as the set of measured magnetic field values $\{B_k(r_1, t), ... B_k(r_8, t)\}$ with $(r_1, ... ,r_8)$ radial positions at distances between 1.5 and 8.5~cm from the axis of rotation, and the applied field along direction $\hat{\imath}$. The choice of the $(i,k)$ couple determines which component (toroidal or poloidal) of the flow is probed. We stress again that we do not address here the question of the contribution of the small scales of turbulence. The recorded signals $B_k(r_n, t)$ are low-pass filtered with a corner frequency equal to 3 times the disks rotation rate $\Omega$.

\begin{figure}[hbt]
\centerline{\includegraphics[width=9cm]{aFig5.eps}}
\caption{Examples of fluctuations of profiles.  Counter rotation of the disks at $\Omega=10$~Hz; applied field along the $z$-axis, $B_{0,z} = 24$~G. (left) transverse induced field due to differential rotation; (right) axial induced field due to the stretching effect.}
\label{profiles}
\end{figure}

 Examples of the evolution in time of such profiles are shown in figure~5. The profiles are shown at time intervals equal to the period of rotation of the disks, and one observes significant fluctuations with respect to the time-averaged curves.  In addition, the points in the profiles tend to vary as a block.  This is evidenced by computing the correlation function, between, say the first element in the array, and the progressively more distant ones. The resulting variation is shown in figure 6(a), where one observes that the maxima of the correlation functions decrease very slowly from 0.9 for the second element down to about 0.4 for the last one. These values do not change as the disks rotation rates are varied from 5~Hz to 20~Hz. For an estimation of a typical correlation length, one notes that the curve can be fitted by an exponential function $\exp{-(r/r_0)}$, with $r_0 \sim R$, the radius of the cylindrical vessel.  This confirms that the fluctuations in the induction are a global feature rather than a local one. In addition, we have observed that the correlation functions are symmetric and peaked around the zero time-lag value.  This behavior is also evidenced in figure 6(b) which shows a space-time diagram of the profile dynamics:  fluctuations are felt simultaneously at all points, {\it i.e.} with a response time of the order of $1/\Omega$.

\begin{figure}[hbt]
\centerline{\includegraphics[width=6cm]{aFig6a.eps}\includegraphics[width=6cm]{aFig6b.eps}}
\caption{(a) Evolution with the distance to the first element in the array, of the maximum (reached at $\tau=0$) of the correlation function $C_{1j}(\tau)= \langle B(r_1, t)B(r_j, t+\tau)\rangle$.  Counter rotation at $\Omega = 5, 10 , 15, 20$~Hz, corresponding to ${\rm R_m}$ values between 1 and 4. (b) Space time diagram, at $\Omega = 15$~Hz. Measurements for counter rotating disks, with $B_{0,x}= 48$~G, induced field along the same direction $B_x$.}
\label{correl}
\end{figure}

\subsubsection{Distance to the mean}
Let us compute a global distance between the mean flow induction profile and  a realisation. Using the ${\cal L}_2$ norm, we define
\begin{equation}
E_k(t) = \sqrt{\frac{1}{N} \sum_{i=1}^{N=8} \left( B_k(r_i, t) - \langle B_k(r_i) \rangle \right)^2 } \ ,
\end{equation}
We find that the time averaged value of $E$ are found to be of the same order of magnitude as the average induced field, that is $\langle E(t) \rangle \sim \langle B \rangle$. In units of the applied magnetic field, we measure $\langle E \rangle \sim 0.07 \ B_0$ for situations in which the maximum of the induced field (${\rm max}_{r_i} \langle B \rangle(r_i)$) is also of the order of $0.1 \ B_0$. These observations indicated that instantaneous induction profiles differ significantly from the time averaged computation.
In addition, we also observe that the distance $E$ has large fluctuations away from its mean value. This is evidenced in figure 7(a) which shows the probability density functions ${\cal P}(E)$ for induction measurements probing the toroidal and poloidal flows. The curves are wide, with events that span several standard deviations. The fluctuations are found to be larger in the case of the induction due to differential rotation than when due to the stretching by the stagnation point in the mid-plane.

\begin{figure}[hbt]
\centerline{\includegraphics[width=8cm]{aFig7.eps}}
\caption{Probability density function of the fluctuations of the ${\cal L}_2$ distance $E(t)$ to the mean induction profile. Counter rotation at $\Omega = 10$~Hz, corresponding to ${\rm R_m} = 2$.}
\label{distance}
\end{figure}

As in our experiment the intrinsic magnetic Reynolds numbers~(defined by the ratio ${\rm max} \langle B \rangle / B_0$~\cite{OdierBilles}) reached in our experiment is always less than 1, we believe that these fluctuations mirror the variations in the flow velocity gradients. However the geometry of these changes is lost with the use of a global ${\cal L}_2$ norm. In the next section we analyse further the profile fluctuations, with the purpose of trying to quantify how the induction deviates from the one expected from the mean flow.

\subsubsection{Polynomial analysis}
Because of the strong correlation in the signal measured by successive elements in the magnetic array, the induction profiles are smooth  and are well described by  polynomials of order three. We do not claim here that the fitting functions are the actual solutions to the induction equation. We use the polynomials as a way to take advantage of the symmetries  associated to the von K\'arm\'an flow. For instance, the mean velocity is reflection - symmetric about the mean plane, and the azimuthal velocity is zero on the rotation axis. As a result, the induction due to differential rotation in the presence of an axial applied field (the $\Omega$ effect) has a zero average in the mid plane at $r=0$. Deviations from this value can then be associated with a symmetry breaking in the mean flow pattern. We thus write an instantaneous profile as
\begin{equation}
\{B_k(r, t)\} = a_0(t) + a_1(t) r+ a_2(t) r^2 + a_3(t) r^3
\end{equation}
and we study in the sequel the evolution of the coefficients $a_j(t)$. \\

\noindent {$\bullet$ \it Mean flow polynomials}\\
We first present the coefficients $\langle a_j \rangle$ for the mean profiles, and their evolution with the disks rotation rate. From the results presented in section 3.1 we expect that they are well accounted for by the structure of the mean flow, {\it i.e.}  $\langle a_j \rangle = a_j({\rm from} \, \langle {\bf U} \rangle)$.

Let us first consider the evolution of $B_x$ in the case of an axial applied field (along $z$). As detailed in section 3.1, induction in the mid plane is dominated by the twisting of the magnetic field lines by differential rotation. Thus, $\langle a_0 \rangle$ should be null because of axisymmetry and $\langle a_1 \rangle$ should increase linearly with the disk (counter) rotation rate. This is indeed observed in figure~8. We have no simple interpretation for the coefficients $a_2$ and $a_3$ which mainly ensure that the induced field vanishes at the outer cylinder (because of the insulating boundary condition).

\begin{figure}[ht]
\centerline{\includegraphics[width=10cm]{aFig8.eps}}
\caption{Polynomial coefficients for the mean induction profile. Axial applied field $B_{0,z} = 24$~G. The measured profiles and corresponding polynomial fit are for ${\rm R_m} = 1, 2, 3, 4$. (top): induction due to differential rotation; (bottom): axial stretching of the applied field.}
\end{figure}

\begin{figure}[hb]
\centerline{\includegraphics[width=10cm]{aFig9.eps}}
\caption{Polynomial coefficients for the mean induction profile. Transverse applied field, $B_{0,x} = 48$~G.  The measured profiles and corresponding polynomial fit are for ${\rm R_m} = 1, 2, 3, 4$. (top): induction due differential rotation; (bottom): transverse compression of the applied field in the mid-plane.}
\end{figure}
\clearpage

Similarly, when ones probes the $z$-induced field  the main effect is due to the stretching of the applied field lines. Since the applied field is uniform, one expects a non zero component $\langle a_0 \rangle$, which increases with  the disk (counter) rotation rate -- as confirmed in figure~8(c). The other contribution is in the $a_2$ coefficient, since here the axisymmetry requires that the odd terms be null.

The situation is equivalent when the applied field is transverse ${\mathbf B}_0 = B_0 \hat{x}$. The average field induced along $x$ in the mid plane comes from the compression of the applied field by the converging flow. The dominant contribution is in $a_0$ (negative) which varies linearly with the rotation rate -- figure~9(d) -- while the axisymmetry imposes $\langle a_1 \rangle  = \langle a_3 \rangle = 0$.  When one probes $B_z$, the dominant contribution comes from the differential rotation whose effect is not felt on the rotation axis, so that $\langle a_0 \rangle = 0$. The dominant contribution is in $\langle a_1 \rangle$, which varies linearly with $\Omega$ (figure~9(b)).\\

\noindent {$\bullet$ \it Fluctuations of the polynomial coefficients}\\
Let us first discuss the case of the fluctuations in the Omega effect, {\it i.e.} for measurements of the toroidal field induced by differential rotation when the applied field is axial. The time variations of the leading coefficient $a_1$ are shown in figure~10(a). One observes very strong fluctuations, although the probability density function is quasi-Gaussian -- Fig.~10(b).  One finds  $a_{1,{\rm rms}} / \langle a_1 \rangle = 114\%$ at a (counter) rotation rate $\Omega=10$~Hz. The spectrum in figure~10(c) indicates that the fluctuations in the profile have a long-time behavior (the slope of the spectrum in the low frequency range is close to -0.7). One thus observes that the fluctuations in the induction profile correspond to a slow process, compared to the turbulence fast small scales and also compared to the disk turn-over time. The fact that the entire induction profile changes in time is clear in figures~10(d,e) which show the correlation between the coefficients $a_0$ and $a_1$. One observes that $a_0$ and $a_1$ are anti-correlated, with $a_0 \sim 0$ only for small deviations of $a_1$ about its mean. In most configurations $a_0$ is non-zero.   As at small ${\rm R_m}$ the induction mirrors the evolution of the velocity, we conclude that the  flow has a slow dynamics with strong deviations from the mean von K\'arm\'an geometry.

\begin{figure}[hbt]
\centerline{\includegraphics[width=14cm]{aFig10.eps}}
\caption{Fluctuations of the polynomial coefficients, for the Omega effect: a magnetic field $B_{0,z} = 24$~G is applied along the rotation axis, and the induction profile $B_\theta \equiv B_x$ is measured. Counter-rotation of the disks at $\Omega = 10$~Hz. (a) time evolution of the polynamial coefficient of order 1; (b) corresponding centered probability density function; (c) time spectrum; (d) and (e): cross-correlation and joint probability density function for the coefficients $a_0(t)$ and $a_1(t)$.}
\end{figure}

We now compare the fluctuations in time for the leading polynomial coefficient and each choice of $(B_{0,i}, B_j)$ -- figure~11. Two kinds of behavior are evidenced. When $(i,j) = (z,x)$ or  $(i,j) = (x,z)$, {\it i.e.} as one probes the toroidal flow (influence of differential rotation) the fluctuations are large. When the induction probes the poloidal component (stagnation point), {\it i.e.} for $(i,j) = (z,z)$ or  $(i,j) = (x,x)$,  the fluctuations are reduced by a factor 3. Note that in figure~10 the coefficients are compared in gauss, so that the $a_1$ values have been multiplied by a length chosen as half the cylinder radius. This choice is justified because in the profiles the induction is maximum at $R/2$ in the corresponding case. In addition, $R/2$ is also close to the  diffusive length. Another feature is the change in the ratio of the $rms$ fluctuation amplitude to the mean. In the case of an applied field parallel to the rotation axis, we had $a_{1,{\rm rms}} / \langle a_1 \rangle = 114\%$ at a (counter) rotation rate $\Omega=10$~Hz for induction resulting from the differential rotation. For the induction due to the pumping motion towards each disks, one has $a_{0,{\rm rms}} / \langle a_0 \rangle = 20\%$. Note that a $20\%$ fluctuation level is what one observes for induction effects in the case of a single rotating disk~\cite{bourgoinvolk}. One thus finds that fluctuations in the induction are larger when associated to the toroidal flow compared to the poloidal velocity component. This is confirmed in figure~11(c,d) where the applied field is transverse to the rotation axis. There $a_0$ for the compression effect fluctuates with a level  $a_{0,{\rm rms}} / \langle a_0 \rangle = 50\%$, while $a_1$ for the BC-effect has $a_{1,{\rm rms}} / \langle a_1 \rangle = 160\%$. In all cases, the PDFs of the time fluctuations of the coefficients are quasi-Gaussian.  \\

\begin{figure}[hbt]
\centerline{\includegraphics[width=8cm]{aFig11.eps}}
\caption{Fluctuations of the polynomial coefficients, for four orientations of the applied and measured components, $(B_{0,i}, B_j)$.  (a) $(i,j) = (z,x)$; (b) $(i,j) = (z,z)$; (c) $(i,j) = (x,z)$; (d) $(i,j) = (x,x)$. Counter-rotation at $\Omega = 10$~Hz. The solid red line corresponds to the mean value and the dashed line to a level of fluctuation equal to 20\% of the mean.
}
\end{figure}

\noindent {$\bullet$ \it Very slow quasi-periodic modes}\\
We must mention that in figure~11(d), the profiles were high-pass filtered at a frequency above 3~Hz (for a disk rotation rate of 10~Hz) before processing . The reason is that there is a quasi-periodic evolution in the induction profile, as can be observed in the  signal displayed in figure~12 (and previously in Figure~4(b)).  The unfiltered  time  variations of  $a_0(t)$  are shown in figure~12(a), and its corresponding time spectrum and probability density function in figures~12(b,c). The spectrum has a marked peak at a frequency $f = 0.1 \; {\rm Hz} \sim \Omega / 100$, with the quasi-periodic evolution also reflected in the bimodal shape of the probability density function.

\begin{figure}[hbt]
\centerline{\includegraphics[width=8cm]{aFig12.eps}}
\caption{Transverse field and compression effect : applied field $B_{0,x}$ and induced component $B_{x}$. (a) time variation of the leading polynomial coefficient $a_0$ (low-pass filtered at frequencies lower than 3~Hz); (b, c) time spectrum and probability density function of $a_0(t)$. Measurement with counter-rotating disks at $\Omega = 10$~Hz.}
\end{figure}

In this configuration, the external magnetic field is transverse. The induced component  probed is parallel to the applied field, and results from the compression of the applied field lines by the poloidal flow converging in the median plane. This effect strongly depends on the exact location of the shear layer~\cite{bourgoinvolk}. Its oscillations with respect to the mid-plane would generate oscillations as in Fig.~12(a). We note that these slow oscillations are reminiscent of the global instabilities of the median shear layer, previously discovered and studied in water prototypes by CEA-Saclay group~\cite{MarieThesis,RaveletPoF}. \\

\clearpage
\section{Discussion and concluding remarks}
In the last case discussed above, the fluctuations are attributed to the existence of large scale (vortical) structures, possibly due to the roll-up of the shear layer in the von K\'arm\'an flow. When these structures exists, it is obvious that the flow is no longer in the averaged configuration pictured in figure~1(a). We would like to show now, that even if one discards the influence of these large scale coherent structures (as we have done by high-pass filtering the data), the inherent turbulence of high Reynolds number von K\'arm\'an flows is such that the fluctuations in the instantaneous flow geometry are very large. The instantaneous flow configurations differ from the mean flow, not only in regards to the amplitude of the toroidal and poloidal velocity components, but also in regards to the symmetries and to the flow overall structure.

We first comment again about the fluctuations, and we study in greater details the  induction profile for the Omega effect. In this case the induction is less sensitive to displacements of the mid-plane shear layer because the differential rotation is found to be rather uniform in the center of the flow~\cite{bourgoinvolk}. For $(B_{0,z}, B_{x})$, the $a_0$ coefficient should vanish because of axisymmetry. Its actual fluctuations in time are shown in figure~13. The mean value $\langle a_0 \rangle$ is equal to $0.5$~gauss; although one expects $\langle a_0 \rangle = 0$, the recorded mean value is really within the precision of our polynomial analysis (limited by the number of elements in the array probe).  On the other hand, the $rms$ amplitude of fluctuations for $a_0$ is $a_{0, rms} = 1.25$~G (for an applied field equal to  24~G), well above its mean. This is a significant variation, even when compared to the mean induction ($\langle a_1 \rangle R/2 = -2.5$~gauss). \\

\begin{figure}[hbt]
\centerline{\includegraphics[width=14cm]{aFig13.eps}}
\caption{$\Omega$ effect, for a counter rotation at $10$~Hz. Time fluctuations of the $a_0$ coefficient (shifted by 0.5~G (see text) so that $\langle a_0 \rangle = 0$ in the plot).}
\end{figure}

Let us now discuss changes in the flow geometry. We compute how long the flow remains in the neighbourhood of its mean configuration, by imposing that both $a_1$ and $a_0$ take values within a standard deviation of their mean. In this case, one finds again that no longer than 50\% of the time is spend in the mean von K\'arm\'an geometry. We stress that: (i) a similar conclusion is reached if one does the estimation from induction effects generated by the presence of the stagnation point (stretching of the axially applied field lines or compression of a transverse field); (ii) the large changes in the polynomial coefficients are related to the long-time dynamics of the flow ({\it i.e.} to frequencies lower than that of energy injection into the flow).

At the low magnetic Reynolds numbers probed in this Gallium experiment, the above effects can be attributed to the hydrodynamics of the flow. Note that such is not necessarily the case for sodium experiments in which non-linear induction processes~\cite{VKSGydro,VKSalpha} or dynamo~\cite{Riga,Karlsruhe} take place. The understanding of such long time dynamics in confined turbulent flows is a challenge. It has now been reported in several experiments (e.g. recently in Rayleigh-B\'enard convection~\cite{Castaing}) but its understanding is still elusive. For instance no known argument gives the time scale of the slowest motion.

These slow global changes in the geometry of the flow may not favor dynamo action. First because all configurations may not be consistent with self generation -- in the sense that the velocity field ${\bf U}({\bf r}, t \; {\rm fixed})$ may not lead to a positive growth rate when inserted in the induction equation. Second, in order for the the magnetic field to grow, the flow must be maintained for many kinetic advection times; indeed one has for the magnetic diffusion time $\tau_M = R^2/\lambda \sim {\rm R_m} \tau_{NL}$, with $\tau_{NL} = R/U$ the time scale of the forcing. Altogether these arguments indicate that a stable flow configuration is desirable for the self-generation of a stationary dynamo. For instance, for flows generated by the rotation of only one disk with the other kept at rest, we have observed that the fluctuations are much less --- cf. Figure~14. The flow spends most of its time in the $s_1t_1$ configuration imposed on average by the driving. As a result, depending on the forcing and large scale hydrodynamic evolution of the flow, one may have to be cautious with approaches that estimate the dynamo threshold from mean flow geometries. This procedure may be valid for purely helical flows in which we have not detected strong fluctuations about the mean; it certainly did yield a correct estimate of the onset of the Riga dynamo~\cite{Riga}. However, it may not be the case for the flow generated by counter-rotation in the von K\'arm\'an geometry. The observed slow dynamics is associated with important changes in the flow topology, and a mean field kinematic simulation may underestimate the threshold. \\

\begin{figure}[hbt]
\centerline{\includegraphics[width=12cm]{aFig14.eps}}
\caption{Probability density function of the fluctuations of the ${\cal L}_2$ distance $E(t)$ to the mean induction profile. (a,b) flow generated by counter rotating disks at $\Omega = 10$~Hz,  axial  applied field, (a) : induction due to differential rotation, (b) due to stretching; (c) flow generated by the rotation of one disk only at $\Omega = 10$~Hz, transverse applied field.}
\end{figure}

{\bf Acknowledgements}\\
We gratefully acknowledge many useful discussions with M. Bourgoin, P. Frick, Y. Ponty, W. L. Shew, and all the members of the VKS team (M. Berhanu, A. Chiffaudel, F. Daviaud, S. Fauve, R. Monchaux, N. Mordant, F. Ravelet). We are indebted to P. Metz and M. Moulin for technical assistance in the development of the experiment. This work is supported by the CNRS and the Rh\^one-Alpes Region Emergence program.

redpajama_set_name: RedPajamaArXiv


What's the Lifespan of a Spare Tire?
My 14-year-old Toyota RAV4 has a cover on the spare tire. I'd like to buy a bike rack that fastens onto the spare tire, but that would require removing the cover. I'm wondering if that will reduce the useful life of the tire. How useful is a 14-year-old spare tire? The new RAV4 models don't seem to have a spare tire at all. What do you think I should do?
That 14-year-old spare tire probably is pretty useless at this point.
Actually, let me correct that: The thing a 14-year-old spare tire is best for probably is holding a bike rack.
I'm guessing no one has looked at that spare tire in about ... oh, 14 years. It's not on most people's to-do list: "Let's see ... quart of milk, call Mom, remove spare-tire cover and examine spare for sidewall cracks ..."
If, by some miracle, your spare tire has found the fountain of vulcanized youth under that cover, then you can keep it a little longer.
A cover probably does increase the useful life of a spare tire somewhat by keeping it out of direct sunlight. But even exposed to direct sunlight, a new spare will last at least six years, maybe longer -- by which time the car will either be dead, and you won't need the bike rack because the bike will be your only remaining vehicle, or you'll have to buy another spare tire for $75.
So, my advice would be to replace the spare, stash the cover, get the bike rack and figure that the health benefits of more bike riding will more than make up for the 12 and a half bucks a year the new tire will cost you.


text:
Dragons Name Squad For Charity Shield Clash
Wed 15 Feb 2017, 02:26 PM
The Dragons have named a 20-man squad for this Sunday's Charity Shield clash with Dragons assistant coach Ben Hornby declaring it's "close to our best squad at the moment".
The Dragons are coming into our traditional season curtain-raiser off the back of a 20-10 victory over the Wests Tigers in their trial match at WIN Stadium last Saturday.
Dragons assistant coach Ben Hornby - speaking to Dragons.com.au - believes it will be a competitive match with Paul McGregor selecting a strong side.
"This is close to our best squad at the moment, the coaching staff thinks," said Hornby.
"While we'll still going to give some guys some opportunities to impress, it'll be close to our starting side. This trial is more about getting those combinations going before the season starts.
"It'll be a good start for the boys to get into competition-mode. We're looking forward to it and I'm sure the Rabbitohs are too."
Charity Shield Squad (in alphabetical order):
Leeson Ah Mau, Euan Aitken, Jack de Belin, Josh Dugan, Jai Field, Tyson Frizell, Jacob Host, Tim Lafai, Nene Macdonald, Kurt Mann, Will Matthews, Cameron McInnes, Josh McCrone, Taane Milne, Jason Nightingale, Russell Packer, Tariq Sims, Joel Thompson, Paul Vaughan, Gareth Widdop.
Get 35% Off Tickets To The Charity Shield Until 5pm Today!

redpajama_set_name: RedPajamaCommonCrawl


text:
<?php
namespace app\models\forms;

class Form9 extends Form {

    const ID = 9;
}

redpajama_set_name: RedPajamaGithub


text:
415 North 10th Street, St. Louis, MO 63101
info@coolfiresolutions.com
Coolfire
Connecting the Unconnected: Making the IoT Work for the Enterprise
President and CEO of Coolfire Don Sharp joins Terri Foudray, CEO of RUMBLE IoT, to weigh in on what it takes for enterprises to leverage IoT technology for cutting-edge applications.
Terri Foudray is the Founder and CEO of RUMBLE IoT, a fully integrated IoT provider that architects and implements custom end-to-end solutions to help companies access data. Here she brings unique insights from working with companies on the strategic and technical aspects of IoT deployments.
Don Sharp, President and CEO of Coolfire, brings a different perspective to the table by focusing on how the data from IoT technologies can inform action and drive value in the enterprise. Together, Terri and Don articulate both the complexity and the immense rewards of well-executed IoT solutions.
Q: Let's talk about the benefits of IoT. Why should companies invest in IoT solutions?
Don Sharp (DS): The biggest benefit is that IoT gives you access to better information to manage your business — and there are thousands of business and government applications for IoT. For instance, taxpayer-funded agencies like the Missouri Department of Transportation can now install sensors on roadways to monitor issues such as snowpack. This can help the agency optimize their resources and deploy snowplows to the streets that need help the most.
If you use the IoT, you don't have to guess when to take action — you can make informed decisions based on real-time data regarding the environment, your equipment, and so on.
Terri Foudray (TF): We're in a world where formerly unconnectable objects are now connected. These connections include infrastructure in smart cities, sensors on manufacturing equipment to improve uptime and throughput, sensors in hospitals to gather data to improve patient care, or sensors in vehicles to make our roads safer and deliver goods faster. These connections are about the extraction of useful data for visibility into what is happening right now — as well as being able to change outcomes.
Q: In which industries have you seen the IoT having the biggest impact?
DS: IoT is becoming important in capital-intensive industries such as transportation and logistics. These businesses can't afford downtime for vehicles, and IoT data can help fix that. It's interesting that these industries have had access to this data for a long time, but they are just beginning to use the technology that allows them to put this data to work. For example, using telematics data, fleet managers can identify problems and schedule predictive maintenance before a breakdown occurs, thus avoiding expensive downtime.
TF: In addition to transportation, the Internet of Things has delivered an immediate benefit in manufacturing, both for managing operational inefficiencies and boosting safety. IoT data helps you predict potential machine failures and allows you to proactively divert your workflow and prioritize allocation of resources. This new operational visibility allows you to keep the factory floor running efficiently and safely while maximizing uptime.
Q: What would you say is the most successful IoT implementation that you've been a part of?
TF: One of our recent solutions in the transportation category was designed to improve safety for first responders and citizens by monitoring first responder driving behavior in real-time. We worked hand-in-hand with the customer to build a solution that unified edge devices and extended the capability of the existing solution for deeper insights to additional factors.
RUMBLE added the ability to see rapid acceleration, hard braking, and rollover events in real-time. The integration at the edge enabled our customer to do real-time in-cab coaching with the driver to change behavior. The solution was rolled out in St. Louis in fire trucks, police cars, ambulances, and other vehicles with great success.
DS: The first IoT project that comes to mind is the implementation of a digital border wall in Central Asia. This particular border spans 200 miles of mountainous terrain that was dangerous and sometimes impossible to secure. Security teams were only aware of illegal border crossings if a guard spotted activity from a watchtower. This made the border a popular route for drug traffickers and terrorist groups.
Our new digital border wall consists of multiple unattended ground sensors and cameras along the entire border. These devices can send real-time data such as imagery and video to the nearest border guards and to command centers when a person or thing crosses the border. Access to this shared data creates a common operational picture for border units and allows them to 'have eyes everywhere.'
Q: Why do you think some businesses are hesitant to move forward with IoT?
TF: There is a lot of buzz around IoT. I believe that executives want to move forward, but get stuck because they simply can't find the right resources to help them build a business case and overcome internal politics — as well as bring expertise in designing a scalable end-to-end solution.
With IoT, there isn't always an obvious path forward. You have to be willing to think outside the box. When you architect a system for a single sensor to a single cloud — that's fairly easy. But when you architect something at scale, that requires more tenacity and expert guidance. IoT is about people coming together with technology to make businesses better.
DS: When it comes to new technology like the IoT, some organizations prefer to wait and see, while the early adopters test the technology and build out new business models. It's a fear of the unknown. They don't want to pick the wrong model or waste time on the wrong solution.
I understand that hesitation, and I know why some organizations may choose to wait. However, there are risks in waiting as well. If you wait, you risk the loss of your employees and your market share to those organizations that choose to innovate. Equally important, you lose the opportunity to learn from innovation.
Q: What advice would you give companies looking to implement a new IoT project?
DS: When you're trying something new, I'm a big believer in starting small and iterating. It's hard to know what to build and what to design. You don't want to put a ton of sensors out there and collect a ton of data and then do nothing with it. And I've certainly seen companies do that.
It's also important to take the time to understand what it is you want to impact so that you can collect the right data and get it to the right people. This will help you define success for your IoT project and will get you closer to delivering the bottom line.
TF: It isn't easy to connect the unconnected. You will need expertise beyond sensors and actuators. The IoT requires you to move data to the cloud and perform analytics. You have to get involved with sensor physics, energy harvesting, and embedded systems. You have to start considering your communication systems and go into your network theory. You start looking at security, cloud dynamics, predictive analytics, machine learning, and more. By the time you're done, you realize that you're touching on all types of engineering domains as you try to set up something reliable and efficient.
Unfortunately, many IT departments are hesitant to work with an outside company because they want to own it and keep it internal. That may be why 70% of IoT projects never move beyond the proof of concept phase. You need to work with someone who understands a variety of complex domains. That often requires you to look outside your organization. I realize it may sound self-serving, but it really pays off to work with a trusted systems integrator with experience in IoT.
Q: According to Gartner's 2019 Hype Cycle, IoT is moving past the hype phase. When do you expect to see an acceleration in adoption?
TF: After you cross the peak of the hype, you start understanding why some pilots didn't work, and why many proofs of concepts didn't pan out. And the early adopters and innovators will learn from that process. They will continue to push forward and will be the ones to capitalize on the technology.
We're at that point now where you have a lot of knowns and unknowns — but the competitors that carve out an advantage in this space will be the ones who make it to the next point in this curve.
DS: That's a hard question to answer, but I would say we'll start to see the next adoption acceleration in 2020. How fast that acceleration will be is difficult to predict, but based on conversations we're having with organizations figuring out IoT business models, I think we'll start seeing more and more adoption next year. That acceleration is going to be driven by industry leaders, as well as tech companies and the providers working with them.
Subscribe to high-speed content. Delivered weekly to your inbox.
Form Location
Stadium Security
Workstream Collaboration
Death by Data
From CIO to Startup: Choosing the Road Less Traveled
More Coolfire
* we will never spam you or sell your information
Lifecycle Stage
© Copyright 2020 Coolfire. All rights reserved.


Roxana Illuminated Perfume introduces a curious collection of natural perfume narratives beginning with Figure 1: Noir, a fragrance tailored for those with a passion for patchouli.
From her tool box of artistic disciplines, Roxana illuminates an eccentric curiosity birthed of primordial earth. Figure 1: Noir is an intriguing perfume oddity, deep and resinous with a loamy plume of botanical musk. This first aromatic curiosity features harmonious notes of patchouli, green vetiver, agarwood, Mysore sandalwood, orris and valerian juxtaposed with the pungent tartness of buchu leaf, kewda, black cumin, green cognac and davana. The effect is as intimate and universal as human skin with a wild animalic shadow.
Figure 1: Noir is available as both a liquid and solid perfume in a variety of sizes and formats including a sample set of both for $17.50.


Write the words to a patriotic song on strips of paper.
Let the boys put them in the right order.
Examples of songs include: The Star-Spangled Banner and America.
Pictures of the associated states (or name typed out) where the landmarks are found.
ü As Scouts arrive, each is given either a landmark or a state.
ü Scouts must find their partners.
ü Cover tables with white butcher paper.
ü Divide each table into four to six sections.
ü At the center of each section, write a large alphabet letter.
ü Challenge each table to come up with as many names of American towns, cities, states, counties, attractions, etc., as they can think of that begin with the letters on their table.
ü They write their answers on the paper with crayons or markers.
ü Prizes can be awarded for participation, longest list, most unique items, etc.
Variation: Make placemats with large alphabet letters in the center. Each individual can play as above.
ü Then cutting them into puzzle pieces with a razor knife.
ü Give each family a puzzle to put together.
1. Place all of the names of capitols of the United States in a container and have a cub scout draw out names until a grid 4 X 4 is completely filled up with letters of capitols or states.
2. It would be best to do this game on a chalk or grease board so that it may be changed often and regularly.
3. The object of the game is to see how many words the Cub Scouts can make up in a time frame of one minute.
4. The cub that has the most valid words wins.
5. Any words that are duplicated by another cub scout do not count - they cancel out each other.
6. Keep this game going until all the 50 states and their capitols have been used.
7. As one or the other is drawn say it out loud and see if any of the cub scouts can name the state to which it belongs.
8. The letters have to be touching and no letter can be used more than once in one word.
9. You can go diagonally, backwards, make angles so long as the letters are touching.
Here are some of the words that I found in the grid-salt, lake, den, vet, red, nerd, as, Ankle, alas, real, lad, leader, ten, etc.
ü Make posters of well known buildings or symbols and put them up around the room.
ü Give each person a numbered piece of paper.
ü Ask them to identify the posters and write the proper name by its corresponding number on the sheet of paper.
Suggestion are: American Flag, White House, Lincoln Memorial, Eagle, Presidential Seal, Uncle Sam, Statue of Liberty, Mount Rushmore, Stone Mountain, etc.
ü Copy an outline map of the United States so that you have one for each Cub Scout or one for each person at the pack meeting.
ü People should write the name of each state and it's capital in the space for the state (or as close as possible to small states, with an arrow pointing to the appropriate state).
ü After the meeting opens, reveal a large U.S. map for everyone to check answers.
ü Give a prize to all who correctly identified the states and capitals.
ü Suggest that they write in any additional information they know, such as the state bird, flower, tree, song, or nickname.
ü People write their names on the papers and turn them in.
ü A leader or other adult uses a list, an encyclopedia, or other reference book about the United States to check the papers.
ü Give a prize to the one with most correct answers.
Write the word AMERICA down the page and write one word beginning with each letter that describes America.
American ABC's -Can You Name Them?
P Give everyone a sheet of paper with the letters A to Z going down the left side.
P Tell them to write one American place or thing for each letter from A to Z.
Using maps and atlases, have the Scouts and families find one geographical location for each letter of the alphabet. Examples: Arizona, Baltimore, Columbia River, Denver, etc.
P Provide boys with crayons and paper so everyone can design a NEW American Flag.
P Have them explain the symbolism behind their new flag.
ü Cut out large versions of the letters in America.
ü Place the pieces in a bag.
ü Give each boy or group a letter and have them put their letters together.
Display scenes from around the United States, pictures of famous Americans, or historical objects from American History – each one should be numbered, but not identified.
As families arrive, they are given a sheet of paper with the numbers along the left side. They must work together to identify each item by name or location.
Can you match up these mottos with correct states?
www.infoplease.com/ipa/A0801718.html has a list of all state mottos – be sure to include your own state in your game!
Give each participant or pair a paper listing the first letter of the name of each state in the US.
Have them write each state on the blanks.
Provide a blank map if this helps.
1. Give the Cubs a phrase made up of two or three words.
2. From that phrase, the Cubs must come up with as many words as possible. Challenge them by making them think of words only with "B", or "S", or "D," or limit them to just three letter words or four letter words.


I need help. Your help. Somebody's help. I am oppressed. Under a heavy burden. Well, not that heavy. But oppressive, yes. And all in the form of one of my favourite authors. Milan Kundera.
It is of course not his fault. But his book of essays, Les Testaments trahis, is weighing heavily on me. Killing my spirit. Softly but surely. I can't finish it. I'm halfway through and now I'm blocked. I can't let it go. But I can't carry on.
You may recall that I started it back in May. With great gusto and enthusiasm, I might add. But maybe my tired brain is not up to this intellectual challenge. His undulating and mesmerising thought processes. And so I put it back on the shelf. Away from sight. And it's been hanging over me ever since.
I can't throw it aside never to read again. Although deep down in the darkest recesses of my being that's what I'd like to do. If I'm honest. Between me and you. But I seem incapable.
And so, MK and his Testaments trahis remain on my Classics Club challenge list. Until I can be brave enough to remove them. If ever I can. Help me. Any advice would be welcome. Please...?


text:
Canistrum improcerum est une espèce de plantes tropicales de la famille des Bromeliaceae, endémique du Brésil et décrite en 2007.

Distribution
L'espèce est endémique de l'État d'Alagoas au nord-est du Brésil.

Description
L'espèce est épiphyte.

Notes et références

improcerum
Flore endémique du Brésil
Espèce d'Angiospermes (nom scientifique)

redpajama_set_name: RedPajamaWikipedia


Mt. Wolf have premierd the stunning visuals for the re-work of their single Bohemia, taken from their 2017 Aetherlight album. This new adaptation of Bohemia comes lavished in an even grander string arrangement, adding a further layer of depth and emotion, and elevating it to even grander, heavenly heights.
Directed by James Ayling, the Bohemia video is an exquisite piece of cinematography. Simply breathtaking guys! Watch it below!
It was imperative that the production quality of the video matched the music and the creative concept to make this piece standout. Bohemia is a hauntingly beautiful composition of music that stands out among the many forms of popular music that is available to listeners.
There is a purity of performance in ballet that expresses the sentiments of the music and conveys the nature of the composition perfectly. The years of practice, hard work and sheer determination to succeed is visible from the seemingly effortless performances from both our skilled dancers, without whom this production would have been entirely unrecognizable.
Mt. Wolf consists of singer-producer Sebastian 'Bassi' Fox, guitarist Stevie McMinn and drummer Alex Mitchell. Having impressed the online tastemakers with their early EP releases Red (2015) and Hex (2016), the band's hallmark splicing of electronic and acoustic elements and layered sounds has earned them comparisons to the likes of Sigur Ros, Bon Iver and The National.


Vulcanism stirs your emotions, and, you discover, your stomach. Olympus Mons, the largest known volcano in our solar system, is rumbling on Mars, with an almost imperceptible stimulation of your appetite and craving for food you never desired before. Unaware, you seek out cellulose gum, lecithin, Diacetyl, Polysorbate 60, and sodium stearoyl lactylate. This results in profound psychological and physiological changes in you. You hurt somebody in your diminished capacity and must be held accountable but your lawyer says there is precedent to get you a full acquittal.
Observations at octagonal section of the ancient Native American earthworks near <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Newark, Ohio, indicate the mounds are precisely aligned for sighting the four moonrises and four moonsets that mark the limits of a complicated lunar cycle that extends every 18.6 years. As it turns out, the monthly cycle marking the northern-most track of the moon precisely is aligned with, um, your cycle. Ancient "Moundbuilders" predicted thousands of years ago that you would have a really CRAPPY day tomorrow.
A planet with 1.76 times the mass of Jupiter has been found to orbit the larger of two stars that form a binary system called Gamma Cephei, 45 light years from Earth. The smaller star orbits the larger one at about the distance from the Sun to Uranus. The conjunction of both stars and planetary object while aligned with the elliptical orbit of the Earth and our own sun provide emerging opportunities to promote your clients. Analysis indicates that a extrasolar planet's gravitational pull is causing the star to wobble slightly. What some would have thought of as negative events garner huge publicity for your clients and they reap benefits from racial slurs, wardrobe malfunctions, foul language and returns to rehab. You bill by the hour so bring it on.
The sun continuously emits charged particles (mostly protons and electrons), which are the byproducts of thermonuclear reactions occurring inside the sun. These charged particles travel away from the sun through space at speeds ranging from 300 to 1,000 km/sec.—about a million miles per hour. Traveling at this high speed, the solar particles can reach the Earth in two to three days, fast, but not as fast as news about the Anna Nicole Smith Baby Paternity Suit. These charged particles are collide with the Earth's electromagnetic field and are constrained to the magnetic field lines much like beads on a wire. The accelerated particles will travel down the magnetic field lines of Earth and collide with the atoms and molecules of the upper atmosphere where the magnetic field lines reach down to surface of the Earth near the north and south magnetic poles. The collisions can excite the atmospheric atom or molecule or they can strip the atmospheric species of its own electron and create an ion. During April, one of these particles will impact your brain and cause distortion of your personal electromagnetic field, causing abrupt personality changes.
The polar axis will point toward the Big Dipper in the northwest, permitting the two-star alignment on Arcturus and Altair, coming within 1/2º of the Ring Nebula (overhead) and M4 in Scorpius (due South). This will result in an abundance of cerebrospinal fluid in the ventricular system of your brain. This will lead you to view bad things as not as bad as they really are. You will have lunch with your not-quite-yet ex-husband because you are lonely.
Full moon causes dark behavior, so your doctor prescribes clozapine which quadruples production ofhistamine H1 receptor-linked activation of hypothalamic AMP-kinase in your brain, causing you to eat more and gain weight, which causes an overload situation and static brake failure in your elevator at work, causing the elevator to plunge to the bottom, as you and the other passengers suffer fractured vertebrae and ribs in addition to head lacerations and contusions. As the rescue workers attempt to extract you and the other survivors from the rubble in the basement the salad you had purchased to bring back and eat at your desk spills open, causing you to trip on raspberry vinaigrette and fracture the remaining pelvic bones that had not already broken.
Venus will appear particularly bright during twilight, caused by reflective carbon dioxide gas mixed with argon in the Venetian atmosphere absorbing near-infrared radiation. This will result in an application of a high-voltage electrical charge that causes the welding of objects together, including a commingling of your front right bumper of your personal vehicle which somehow comes in contact with a car already parked in a spot next to the one you wanted to get into.
A stream of charged particles (i.e., a plasma) that was ejected from the upper atmosphere of our sun, known as the solar wind, effects the Earth's magnetic field which in turn resulted in a pressure differential below the lithosphere where the asthenosphere, while solid, developed relatively low viscosity and shear strength and began flow like a liquid on geological time scales. The deeper mantle below the asthenosphere is more rigid again. This is, however, due not to cooler temperatures but to high pressure. You act on deep-seed resentment towards the people in accounts payable who ignore your invoices that clearly state when the bill is overdue.
A comet with a hyperbolic orbit will make its nearest approach to Earth, closing to a mere 10 million miles as it passes over the planet's Northern Hemisphere. Once it leaves the solar system, this comet will never return as it will go into interstellar space. and in dark sky areas it's tail may be seen to cover about 20 degrees on the sky (40 times the apparent diameter of the full moon) corresponding to well over 3 million miles. The tail grows as the sun heats and sublimates (changes directly from solid to gas) the material on the icy surface of the comet nucleus, sending jets of gas and dust into space. The material is swept back by the solar wind, so comet tails usually point away from the sun rather than simply trailing along behind in the comets' orbit. The comet will cause motorists traveling to work from rural areas to be distracted and attempt to visually calculate the point where the comet penetrates the orbital plane. So you decide to work from home, which allows you to watch Court TV all day.
A rare alignment of Jupiter's largest moons, Io, Ganymede, and Callisto, will present the opportunity you have been waiting for – the big break that you really do nothing to deserve. These moons are roughly the same size as Earth's Moon. Observing the moons' shadows on Jupiter is a rare occurrence — such an alignment happens once or twice every decade. These bodies orbit the planet at different rates, which limits their opportunities to cast shadows. Outermost Callisto, for example, orbits much slower than the other two satellites. Its shadow moves across Jupiter once for every 20 times Io crosses the planet. Normally, methane gas in the Jupiter's dense atmosphere limits the penetration of sunlight down to the planet's surface, but in your case methane will open the door to a bright new future at the top.
Massive clouds of gas within the margins of the Milky Way galaxy are creating new stars by raining gas onto the plane of the galaxy. This presents an opportunity for you. But it is a fleeting one. These massive gas clouds, called high-velocity clouds, constitute a mechanism by which the galaxy is seeded with the stuff of stars and solved a long-standing question of galactic evolution. This influence means you will be creative at work and in love, perhaps in a way that evolves the species.
1 Comment to "Your JOTW Communicator's Horoscope for April 2007"
>This will result in an application of a high-voltage electrical charge that causes the welding of objects together, including a commingling of your front right bumper of your personal vehicle which somehow comes in contact with a car already parked in a spot next to the one you wanted to get into.
Am I just ahead of my time?


text:
How To Talk To Your Kids About Sex Day #4
February 12, 2021 February 12, 2021 by Sara LittlejohnNo Comments
How To Talk To Your Kids About Sex
#4 Fill The Sponge
"At what age should I tell my kids about sex?" This is the most popular question parents want to know. If you're looking for me to give you an exact age, it's not going to happen. But I'm happy to tell you why we chose the ages we did, and give you some basic guidelines you should consider when thinking about what age you should tell your child about sex.
Remember, one of the goals is to TALK EARLY. All 4 of our kids were between the ages of 6-9 when we had our first actual conversation about sex, not just a conversation about body safety and the Cookie Monster. Here's some of our thinking.
Kid's brains are like dry sponges, and it was an important value/priority to us to be the ones who filled the sponge with knowledge, information, power, and truth. We wanted to be their #1 go-to not only when it came to their sex education, but really in all of life. We determined if we started young and filled their sponges with truth, loveliness, and security by the time ANYONE ELSE (peers, teachers, TV, books, movies etc…) started pouring knowledge into our little sponges, our kids' brains would be saturated with a proper understanding and a foundational bedrock to stand on. And all other information would just roll off like water does when it's trying to saturate an already full sponge. (For the record, I cannot take credit for this awesome analogy. I heard it somewhere, but honestly have no idea where. *Dear children, this is what we call avoiding plagiarism or a lawsuit. Cite your sources!*
Our children ARE going to learn about sex, the question is who is going to get to write the story first. We wanted to write this story! Not some uneducated joker on the playground. We wanted to be the first to share with our kids the beauty and design of sex. We wanted to equip them with the truth. We wanted them to be ahead of the curve, not behind.
Here's to filling the sponge!
Counseling, Parenting, Sexsex
How To Talk To Your Kids About Sex Day #13 April 8, 2021
How To Talk To Your Kids About Sex Day #12 March 11, 2021
How To Talk To Your Kids About Sex Day #11 March 8, 2021
How To Talk To Your Kids About Sex Day #9 February 26, 2021
Living In The Storm
Want to get the latest in your mailbox?
Get updates from Sara!
Blog Archives Select Month April 2021 (1) March 2021 (3) February 2021 (9) May 2017 (1) December 2016 (1) November 2016 (3) August 2016 (2) May 2016 (1) April 2016 (11) January 2016 (2) December 2015 (2) November 2015 (2) October 2015 (3) September 2015 (2) August 2015 (2) July 2015 (3) June 2015 (1) May 2015 (2) April 2015 (4) March 2015 (3) February 2015 (4) January 2015 (5) December 2014 (3) November 2014 (5) October 2014 (5) September 2014 (4) August 2014 (4) July 2014 (4) June 2014 (3) May 2014 (4) April 2014 (4) March 2014 (4) February 2014 (5) January 2014 (5) December 2013 (2) November 2013 (5) October 2013 (8) September 2013 (8) August 2013 (9) July 2013 (5) June 2013 (7) May 2013 (8) April 2013 (15) March 2013 (7) February 2013 (11) January 2013 (6) December 2012 (10) November 2012 (8) October 2012 (11) September 2012 (10) August 2012 (13) July 2012 (9) June 2012 (10) May 2012 (10) April 2012 (8) March 2012 (14) February 2012 (10) January 2012 (13) December 2011 (10) November 2011 (14) October 2011 (14) September 2011 (17) August 2011 (20) July 2011 (11) June 2011 (17) May 2011 (18) April 2011 (12) March 2011 (26) February 2011 (17) January 2011 (19) December 2010 (17) November 2010 (18) October 2010 (26) September 2010 (14) August 2010 (3)
© Sara Littlejohn | Wordpress Website Designer Nuzu Net Media


Are you searching for expert writers on Excel Assignment? Talk to us right now through Live Chat!
Get Professional Excel Homework Help for Completing Your Excel Homework Assignments Now!
Are you worried about Excel COMPLEX functions? Do you want to complete your excel homework assignments? If you are searching for Microsoft excel homework help online, then get in touch with our expert on homework assignments now! You are now at the best place.
Excel homework help is in great demand. The students are looking for excel assignment help. The MS Excel spreadsheet application was developed for android, windows, iOs, and macOS by Microsoft. Excel spreadsheet is essential for drawing tables and graphs, histograms, plot tables or doing any mathematics calculations. Excel spreadsheet application is also used broadly for managing office tasks on a regular basis, data and optimization problems.
Microsoft Excel features graphing tools, calculation, pivot tables, and a macro programming language known as Visual Basic for Applications. Excel spreadsheet application is a vast place to cover for accomplishing such tasks. If you face problem to complete your excel homework assignments then you are now at the right place.
Dream Assignment is the best excel assignment help provider. We have experienced Excel experts for the assignments and you will never face any trouble at the time of execution.
An excel file has a grid of cells decorated in columns and rows. Columns are the vertical lines, which are denoted with letters. The rows are horizontal lines, which are designated with numbers. Statistical, financial or educational tasks are basically accomplished by Excel spreadsheet.
Why Student want Excel Homework Help?
● Lack of understanding on Excel questions.
● Lack of knowledge to use software for accomplishing tasks.
● Lack of problem solving skills.
Solving excel homework assignments is not an easy work! You must have significant knowledge of software. It is difficult for those who do not understand the question properly. A sound knowledge of computer is important to accomplish an excel assignment. Every student does not have the same level of expertise in handling computer and software. You need to plan for completing an excel assignment perfectly.
You may find numerous excel project help service providers over the internet. If you need help with excel assignment from the excel experts online, then you must contact Dream Assignment through live chat, email or phone now! We have a large number of experienced writers in excel. They offer excel assignment help to the students of high school, universities, and colleges.
How Our Experts can Guide You with Excel Assignment Help?
Are you looking for excel assignment help? We are ready to provide you the best service on Excel. We will assist you in solving quizzes on excel assignment methodically. You will understand the whole process. You can get the best grade with our guidance. If you face any difficulties in your assignment, we are here to guide you. You can get proper problem-solving guidance. If you want see Excel sample projects, we can definitely show you.
● Help you to comprehend the excel homework assignment.
● Providing important tips and tricks with precise guidelines to solve similar types of excel assignment questions.
● Providing excel sample projects will help you to complete the assignment easily.
Dream Assignment aims to provide high-quality excel assignment help. They can solve assignments methodically within deadline. It helps the student to realize the whole concept. The experts can solve such type of assignments comfortably.
Why Students Choose Our Excel Experts Online for Their Excel Project Help?
The solution of mathematics or statistics calculation in excel can reduce your stress. It can save your valuable time also! For excel projects, you need to have a precise knowledge of functions and formula. You can get solution of the Excel problems. We also provide assignment guidance on financial accounting assignment help.
What are the reasons for choosing Excel Homework Help?
Dream assignment has a team of highly qualified professional who can help you in excel projects. We have experience in solving all kinds of assignment. They are dedicated enough to provide you the best excel homework assignments writing services.
We have provided lots of excel assignments with solutions to the students. Our customers are quite consistent over the years. It is possible due to the uniqueness of our service. You will get original assignments on Excel. The homework is free from all kinds of grammatical errors!
We know that every student doesn't have the same financial strength to avail high-quality excel assignments with solutions from the experts. The reason is that the price of assignment writing service is quite high. We understand the financial constraint of the students. We have taken a decision to provide our best quality excel project help service at an affordable price. The projects are always completed within the deadline.
Dream Assignment is one of the best academic writing service providers. We provide high-quality homework assignments in every corner of the world. Our experts are dedicated in providing high-quality excel assignments with solutions. We are always focusing on the quality assignment. For that reason, our customers are quite consistent. We have received positive feedback from our clients till now.
Our excel project help team is knowledgeable and experienced. They are available most of the time in a day to assist you. If you need to add any content or need to modify any data, you can talk to our experts any time! We are happy to serve you. So if you have any problem you can feel free to consult with our experts any time.
It is not possible to remember all the formulas and function of Excel! It is tough to solve critical excel assignment most of the time. Besides having schools, colleges or universities, the students want to enjoy their life. But you should not worry about the excel assignments. Our excel assignment help writers are available 24/7 to guide you.
So, if you have any problem on excel-related projects, you can come to us and submit your assignment now! You should mention your deadline. The experts can provide accurate excel assignments with solutions.
Therefore, you might be searching "Do my Excel Homework". Our assigment help experts can solve your anxieties on Excel. You can definitely avail our high-quality Excel homework help at an affordable price today!


text:
Portugal bond auction raises 1.25bn euros - 10 year bond at 6.719%
Wednesday, 12 January 2011 | European Affairs
Portugal has raised 1.249bn euros (£1.04bn; $1.62bn) in an auction of four and 10-year bonds. The yield, or the interest rate Portugal must pay to borrow funds, on the 10-year bond was an average 6.719%.
Markets had been watching closely to see how easily - or not - the debt-hit nation could raise funds. Yields had hit a recent fresh high on its 10-year bonds of 7.3%, before falling to 6.77% on Wednesday morning before the auction. The sale was seen as a measure of Lisbon's ability to raise funds on the financial markets after its debt and deficit problems raised the amount it had to pay to borrow cash.
'ECB active'
Bond buying by the European Central Bank (ECB) had helped keep the yield below 7%.
"Probably the most important thing for the 10-year yield is that the 7% level was not breached," said Michael Leister, of West LB in Duesseldorf.
"The ECB have been very active in past days stabilising the market and sentiment. "
"It remains to be seen over the coming trading session whether this will be a turnabout for Portugal and whether recent spread tightening can be sustained."
The four-year bond yield was 5.396%.
Bail-out?
There has been speculation Portugal could join Greece and the Irish Republic in needing an international bail-out, something it has denied. The country's borrowing costs have surged as investors worried over its financial health. Lisbon has argued its situation is different from Greece and the Republic of Ireland - both of which have agreed to bail-outs from the European Union and International Monetary Fund. It says that its deficit and debt are lower than those nations, that it has not suffered a bubble in property prices and that its banks are sound. And the European Commission has said there are no discussions under way on an EU-International Monetary Fund bail-out of Portugal. However, some analysts still believe the country will need to seek funding help.
"Our country analysts still forecast that Portugal will be required to receive funds from the emergency credit facility," said Kevin Dunning, economist at the Economist Intelligence Unit.
"And there is a high risk that if the interest charged on those funds is as high as for Ireland, this will slow Portugal's efforts to reduce its budget deficit."
Spanish auction
Analysts believe that while Europe could support Portugal, a bail-out of Spain would stretch the existing bailout fund. Greece was the first eurozone nation to take a bail-out when a three-year 110bn-euro deal was agreed. The Irish Republic's 85bn-euro bail-out package was agreed last month. A debt sale due on Thursday by Spain will also be closely watched by investors.
European Affairs's blog | |


text:
AllRiflesGearLearnNews
Gear: Accessories
The Benefits of Electronic Hearing Protection
Technology has progressed at an amazing pace in the last few decades, but the shooting world hasn't been left behind in this digital age — modern technology has brought electronic hearing protection to the general shooting public at an affordable price.
However, many avid shooters don't understand exactly how electronic hearing protection works or why they should buy it.
The great thing about slim electronic ear pro, like these Walker's Razors, is that they can still be used when shooting rifles, as the cups don't interfere with a proper cheek weld.
I am no true believer — I was in my 40s before I ever put on a pair of electronic muffs, but now I kick myself that it took me so long to take advantage of what is a real game-changer. Electronic hearing protection is most commonly seen in the form of over-the-ear muffs, so let's look at them first.
All About Muffs
Standard non-electronic muffs are called "passive" hearing protection. The cups around a shooter's ears are filled with sound-absorbing foam, which slows down/muffles/reduces the incoming sound waves so gunshots and other loud sounds are no longer a threat to their hearing.
As a result, however, it is harder to hear sounds at ordinary volume levels. I can always tell who at the range is wearing passive muffs, because they're shouting in order to have a "normal" conversation. FYI, if you don't wear some sort of hearing protection while shooting, people will soon have to shout at you all the time.
These Walker's Ultimate Quad Connect muffs have four microphones, independent volume control, and a number of other features'¦.but as a result they're a bit blocky, and maybe not the best choice when shooting a rifle as they may interfere with your cheek weld.
Earmuffs for electronic hearing protection have standard ear cups with sound-absorbing foam just like in passive muffs, so if a battery dies, a shooter's hearing will still be protected. Where they differ from passive muffs is the microphones on the outside of the muffs, which pick up sounds, amplify them and deliver them to a shooter's ears electronically.
With the volume control turned all the way up, I've found electronic muffs allow me to hear better than I can with my bare ears — which is why many hunters wear them in the field. And yes, firing only a few rounds a year without electronic hearing protection while hunting can still irreparably damage anyone's hearing.
Early electronic ear muffs (and modern inexpensive ones) feature a "stop gate." If the muffs sense a loud sound above a certain decibel level, the amplifier simply shuts off. When the sound stops, the amplifier turns back on.
This works, but the resulting audio experience to the shooter's ear can be a bit clipped. If someone nearby is shooting a lot while shooters are trying to have a conversation, it will sound like their muffs are shutting on and off. These older/cheaper muffs also usually only had one microphone, and it was tough to tell the direction from which the sound was coming.
Convenience is important, and being able to fold up your ears so they fit in your range bag is a nice bonus.
Most modern models of electronic hearing protection feature the latest amplifier technology, which offers "sound compression." This lets shooters hear all of the low-level environmental sounds going on around them, including conversation, footsteps, even the wind, but when a loud sound, like gunshots, occurs, the sound is not cut off but rather compressed into a lower volume. The sound is essentially continuous as opposed to cutting in and out.
One great advantage of electronic hearing protection is that shooters won't have to pull their muff away and expose their ears to have a conversation. As soon as they do that, someone nearby is likely to start shooting unexpectedly, and they'll be jerking their muff back into place. I've seen that happen dozens of times.
Modern electronic hearing protection also usually features more than one microphone (one on each muff) so it is easier to determine the direction the sound is coming from. This is very important if shooters are wearing electronic hearing protection when hunting or in a tactical environment. Most electronic muffs seem to be powered by widely available and inexpensive AAA batteries, which last for hundreds of hours.
For a look at all the technological advancements electronic muffs offer compared to passive muffs, check out the specs on the "Ultimate Series" from Walker's. These electronic muffs feature four hi-gain omni-directional microphones, 9x hearing enhancement, two independent volume controls, sound-dampening composite material, which contributes to the highest (27dB) noise reduction rating for any muff under $300 and sound activated compression. They're also available in Mossy Oak and Realtree camo patterns for hunters.
However'¦.there's no such thing as a free lunch. Muffs big enough to have all of the above features can be a bit blocky, not to mention expensive. Blocky doesn't matter when shooting a handgun, but most people don't want their muffs getting in the way when they have to put a cheek on a rifle stock. Also, these big, full-featured muffs just aren't as convenient for storage/transport.
With modern advancements it is now possible to make very slim electronic muffs that still provide excellent electronic hearing protection. Walker's has a new line of slim folding muffs called the Razor Series. Two omni-directional microphones, HD sound output with independent volume controls, sound activated compression, 23dB noise reduction rating'¦and a suggested retail price of only $69.99! Isn't technological advancement awesome?
Earplug Technology
If electronic muffs are so great, why was I in my 40s before I tried a pair? Simply because nothing is perfect for everyone all the time. I live in Michigan, which means if it's warm enough to shoot outside it is probably hot and humid — and the last thing I wanted to do on a hot and humid day was clamp a pair of earmuffs on my head. So I was an earplug guy for years, and still prefer them if I'm shooting where it's hot.
Razor XV electronic hearing protection from Walker's offers an incredible 31 dB noise reduction due to their dense foam tips.
Earplugs are fine if shooters are outdoors, away from other people, but if they're on a line with many rifles or shooting anything indoors or in an enclosed space, plugs usually don't provide enough hearing protection.
Muffs alone might not, either. However, if shooters wear electronic hearing protection over plugs (I've seen that combo quite often, especially in really loud environments) and turn the muffs all the way up, they can still have a normal conversation while enjoying nearly double the noise reduction of just plugs or muffs alone. That may seem like overkill'¦.but there is no such thing as too much hearing protection.
One thing shooters may not realize is that earplug technology has improved along with earmuff technology. For a while now, I've been seeing young people listening to music on retractable earbuds attached to a half halo (for lack of a better term) that sits around their neck. Being out of my teens I'm often a little slow to grasp emerging tech, and wasn't sure what I was looking at, but a little research recently showed me what these were — Bluetooth-enabled earbud headsets.
I also learned there were versions designed for shooters. Yes, you read that right, there are now electronic earbuds, which perform similarly to electronic muffs, with omni-directional microphones, sound activated compression, etc. Who knew?
Electronic earbuds for the shooting sports have arrived. Walker's Razor XV (shown here) are Bluetooth enabled so you can take phone calls or listen to music without removing your ear protection.
In researching these earbud headsets, I have to admit I was shocked at their features. For example, the Razor XV model from Walker's offers a noise reduction rating of 31 dB! That's incredible, and better than most muffs.
That kind of sound abatement is apparently possible through the use of dense noise reducing foam tips. These top-of-the-line earbuds also offer a Bluetooth connection, so shooters can answer a phone call without removing their headphones.
These earbuds also have an independent volume control, so shooters can listen to music without having to worry about missing any range commands. The speakers in the earbuds are made in the same factory that makes Bose speakers, so the sound quality is excellent.
Thanks to modern technology and electronic hearing protection, there's never been a better time to enjoy shooting while protecting hearing.
Review: Savage Arms MSR 15 LR
David Fortier - May 17, 2019
The new MSR 15 Long Range in .224 Valkyrie reaches out with authority.
.22 Nosler vs .224 Valkyrie
Brad Fitzpatrick - May 02, 2019
For decades, things were quiet on the .22 centerfire front. Starting in 2017, shooters were...
Marlin Model 1895-.444 Marlin
The Marlin Model 1895-.444 Marlin is a handy, powerful rifle capable of taking down elk,...
All About .300 Blackout
The .300 Blackout is here to stay, and we take some time to look at new technology surrounding this cartridge. Next, we pit subsonic rivals against each other before stretching the legs of this CQB round out to 600 yards from a short 9-inch barrel.
Ruger Launches New American Rifle Predator in 6.5 Grendel
OSG's Lynn Burkhead and Ruger's Matt WIlson kick off SHOT Show 2018 by taking a look at the Ruger Predator.
Hornady 6MM Creedmoor
Tom Beckstrand and Neal Emery of Hornady highlight the 6MM Creedmoor ammo.
Three Rangefinder Products from Leica
If you're a serious shooter with deep pockets, these Leica products are worthy of...
Review: Tromix .375 SOCOM
David Fortier - March 15, 2019
The new Tromix .375 SOCOM offers great performance with less recoil than its .458 brother.
RifleShooter Holiday Gift Guide (2019)
The RifleShooter staff put together their gift guide for the upcoming holiday season, with...
Technology has progressed at an amazing pace in the last few decades, but the shooting world...
RifleShooter 2018 Holiday Gift Guide
J. Scott Rupp - November 06, 2018
RifleShooter editor Scott Rupp provides a comprehensive list of gifts for the upcoming holiday...
Rifle Shooter
'); $(el).addClass('full-video-small'); activePinned = true; //previousPlayer = el; } } else if (akamai.amp.Utils.getViewability(el.parentElement) === "full") { $(el).removeClass('full-video-small') } }) }); function sendMessage(eventTrigger, _iframe) { var hostUrl = "https://www.rifleshootermag.com"; var message = eventTrigger; try { _iframe.contentWindow.postMessage(message, hostUrl); } catch (e) { console.log('error', e) } } }); $(window).scroll(); }); // end: document.ready()