DIELECTRIC EVIDENCE FOR ACETONE HYDRATE

1963 ◽  
Vol 41 (2) ◽  
pp. 264-273 ◽  
Author(s):  
G. J. Wilson ◽  
D. W. Davidson
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
High Frequency ◽  
Water System ◽  
Low Frequency ◽  
Water Molecules ◽  
Incongruent Melting ◽  
High Frequency Dielectric Constant ◽  
System A ◽  
Acetone Water

The phase diagram of the acetone–water system shows that acetone hydrate decomposes at an incongruent melting point. The existence of acetone hydrate is confirmed by a study of the low-frequency dielectric properties of this system. A dispersion region, related to the relaxation of water molecules in the clathrate structure, is characterized by a "static" dielectric constant and an activation energy about half as large as the corresponding values for ice, and by a limiting high-frequency dielectric constant of about 7 at 200° K. The magnitude of the latter is attributed to orientation of acetone molecules within the larger cavities of the hydrate structure.

Reduction Methods of Structure Models for Control System Purposes

2016 ◽  
Vol 248 ◽  
pp. 119-126 ◽  
Author(s):  
Andrzej Koszewnik ◽  
Zdzisław Gosiewski
Keyword(s):  
Control System ◽  
High Frequency ◽  
Closed Loop ◽  
Flexible Structures ◽  
Low Frequency ◽  
Point Of View ◽  
Closed Loop Systems ◽  
System A ◽  
Reduction Methods ◽  
The Stability

To design vibration control system for flexible structures their mathematical model should be reduced. In the paper we consider the influence of the model reduction on the dynamics of the real closed-loop system. A simply cantilever beam is an object of consideration since we are able to formulate the exact analytical model of such structure. As a result of reduction the model with low frequency resonances is usually separated from the high frequency dynamics because high frequency part of the model is naturally strong damped. In order to estimate dynamical system for control purposes in the paper we applied a few orthogonal methods such as: modal, Rayleigh-Ritz and Schur decompositions. As it is shown all methods well calculate resonances frequencies but generate different anti-resonances frequencies. From control strategy in point of view of the flexible structures these anti-resonances have significantly influence on the stability and dynamics of the closed-loop systems.

High-frequency dielectric constant of layered Fe, Co, and Ni dihalides

1984 ◽  
Vol 29 (6) ◽  
pp. 3617-3622 ◽  
Author(s):  
I. Pollini ◽  
G. Benedek ◽  
J. Thomas
Keyword(s):  
Dielectric Constant ◽  
High Frequency ◽  
High Frequency Dielectric Constant

scholarly journals Monovision and the Misperception of Motion

2019 ◽  
Author(s):  
Johannes Burge ◽  
Victor Rodriguez-Lopez ◽  
Carlos Dorronsoro
Keyword(s):  
Processing Speed ◽  
High Frequency ◽  
Low Frequency ◽  
The United States ◽  
Illusory Motion ◽  
Apparent Paradox ◽  
System A ◽  
Spatial Frequencies ◽  
Stereo Motion ◽  
Pulfrich Effect

Monovision corrections are a common treatment for presbyopia. Each eye is fit with a lens that sharply focuses light from a different distance, causing the image in one eye to be blurrier than the other. Millions of people in the United States and Europe have monovision corrections, but little is known about how differential blur affects motion perception. We investigated by measuring the Pulfrich effect, a stereo-motion phenomenon first reported nearly 100 years ago. When a moving target is viewed with unequal retinal illuminance or contrast in the two eyes, the target appears to be closer or further in depth than it actually is, depending on its frontoparallel direction. The effect occurs because the image with lower illuminance or contrast is processed more slowly. The mismatch in processing speed causes a neural disparity, which results in the illusory motion in depth. What happens with differential blur? Remarkably, differential blur causes a reverse Pulfrich effect, an apparent paradox. Blur reduces contrast and should therefore cause processing delays. But the reverse Pulfrich effect implies that the blurry image is processed more quickly. The paradox is resolved by recognizing that: i) blur reduces the contrast of high-frequency image components more than low-frequency image components, and ii) high spatial frequencies are processed more slowly than low spatial frequencies, all else equal. Thus, this new illusion—the reverse Pulfrich effect—can be explained by known properties of the early visual system. A quantitative analysis shows that the associated misperceptions are large enough to impact public safety.

Required Data Collection Times for Steady and Quasi-steady Experiments

2017 ◽  
Author(s):  
Robert F. Roddy ◽  
David E. Hess
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Frequency Noise ◽  
Surface Ship ◽  
System A ◽  
Low Pass ◽  
Collection Period ◽  
Almost All ◽  
Low Pass Filters

One of the requirements in performing steady or quasi-steady experiments is the determination of adequate collection times so that the data will not be biased due to low frequency energy in the data stream. Since virtually all steady experiments run at DTMB have low pass filters in line with the signal conditioning, high frequency noise is not a consideration in determining the required collection times. At both EMB and DTMB almost all of the surface ship drag measurements were made using gravity type balances until about 1970. These balances used both springs and dampers to modify the natural frequency of the system so that a good average model drag could be determined in a 5-6 sec collection period. Submarine model experiments began using block gages to measure drag beginning in the late 1950's. For these experiments crude methods were used to damp the output data but, to the author’s knowledge, no methods were ever put into place that was analogous to the springs and damper system. A method for determining the required collection times for any steady or quasi-steady experiment is presented along with sample cases showing the necessity for, and the utility of, using such a method.

Enhancing the Weak Signal With Arbitrary High-Frequency by Vibrational Resonance in Fractional-Order Duffing Oscillators

2017 ◽  
Vol 12 (5) ◽  
Author(s):  
J. H. Yang ◽  
Miguel A. F. Sanjuán ◽  
H. G. Liu
Keyword(s):  
Fractional Order ◽  
High Frequency ◽  
Low Frequency ◽  
Original System ◽  
Scale Transformation ◽  
Weak Signal ◽  
Vibrational Resonance ◽  
High Frequency Signal ◽  
System A ◽  
Auxiliary Signal

When the traditional vibrational resonance (VR) occurs in a nonlinear system, a weak character signal is enhanced by an appropriate high-frequency auxiliary signal. Here, for the harmonic character signal case, the frequency of the character signal is usually smaller than 1 rad/s. The frequency of the auxiliary signal is dozens of times of the frequency of the character signal. Moreover, in the real world, the characteristic information is usually indicated by a weak signal with a frequency in the range from several to thousands rad/s. For this case, the weak high-frequency signal cannot be enhanced by the traditional mechanism of VR, and as such, the application of VR in the engineering field could be restricted. In this work, by introducing a scale transformation, we transform high-frequency excitations in the original system to low-frequency excitations in a rescaled system. Then, we make VR to occur at the low frequency in the rescaled system, as usual. Meanwhile, the VR also occurs at the frequency of the character signal in the original system. As a result, the weak character signal with arbitrary high-frequency can be enhanced. To make the rescaled system in a general form, the VR is investigated in fractional-order Duffing oscillators. The form of the potential function, the fractional order, and the reduction scale are important factors for the strength of VR.

Dielectric Properties of Polyester Reinforced with Carbon Black Particles

2011 ◽  
Vol 110-116 ◽  
pp. 170-176
Author(s):  
Omed Ghareb Abdullah ◽  
Dana Abdull Tahir ◽  
Gelas Mukaram Jamal ◽  
Salah Raza Saeed
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Carbon Black ◽  
Low Temperatures ◽  
Ac Conductivity ◽  
Low Frequency ◽  
Frequency Range ◽  
Exponential Factor ◽  
Increasing Temperature ◽  
Dielectric Permittivity And Loss

Dielectric constant and ac conductivity of Polyester doped with carbon black are investigated in the frequency range (0.5-103) KHz and within the temperature range (26-80) oC. Dielectric permittivity and loss tangent reduced with increasing frequency and increase with increasing temperature. The ac conductivity σac for all samples were found to be weak frequency dependent at low frequency, however vary with frequency as a power law ωs at higher frequency range. The variation of frequency exponential factor s between 0.63 and 0.77, indicates a dominant hopping process at low temperatures. From the temperature dependence of dc conductivity, the increase of activation energy was observed with carbon black concentrations.

Some Rationale for the Unusual Behavior of the Dielectric Constant of Cu2O

1973 ◽  
Vol 51 (6) ◽  
pp. 680-685 ◽  
Author(s):  
F. L. Weichman
Keyword(s):  
Dielectric Constant ◽  
High Frequency ◽  
Low Temperatures ◽  
Low Frequency ◽  
Depletion Layer ◽  
Temperature Dependent ◽  
Unusual Behavior ◽  
Temperature Variations ◽  
Very Low Frequency ◽  
Semiconducting Material

The very low frequency dielectric constant in Cu2O varies over wide limits and is highly temperature dependent. At sufficiently low temperatures the dielectric constant for all samples reduces to the high frequency value of about 7.5. Small variations in the high frequency value are easily explained as being due to the known presence of copper crystals embedded in the semiconducting material. The low frequency and temperature variations will be related to the variation in the depletion layer formed around each copper inclusion. Calculations are based on highly oversimplified size, shape, and distribution of the copper inclusions.

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