Practical Applications of The Volume Clock:Insights into the High-Frequency Paradigm

2013 ◽  
Vol 1 (2) ◽  
pp. 1.5-4
Author(s):  
Kathryn Christopher
Keyword(s):  
High Frequency ◽  
Practical Applications

scholarly journals Activity-Integrated Hidden Markov Model to Predict Calving Time

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 385
Author(s):  
Kosuke Sumi ◽  
Swe Zar Maw ◽  
Thi Thi Zin ◽  
Pyke Tin ◽  
Ikuo Kobayashi ◽  
...  
Keyword(s):  
Markov Model ◽  
Hidden Markov Model ◽  
High Frequency ◽  
Hidden Markov ◽  
Dairy Farm ◽  
Integrated Approach ◽  
Production Cycle ◽  
Practical Applications ◽  
Standing Up ◽  
Behavioral Activities

Accurately predicting when calving will occur can provide great value in managing a dairy farm since it provides personnel with the ability to determine whether assistance is necessary. Not providing such assistance when necessary could prolong the calving process, negatively affecting the health of both mother cow and calf. Such prolongation could lead to multiple illnesses. Calving is one of the most critical situations for cows during the production cycle. A precise video-monitoring system for cows can provide early detection of difficulties or health problems, and facilitates timely and appropriate human intervention. In this paper, we propose an integrated approach for predicting when calving will occur by combining behavioral activities extracted from recorded video sequences with a Hidden Markov Model. Specifically, two sub-systems comprise our proposed system: (i) Behaviors extraction such as lying, standing, number of changing positions between lying down and standing up, and other significant activities, such as holding up the tail, and turning the head to the side; and, (ii) using an integrated Hidden Markov Model to predict when calving will occur. The experiments using our proposed system were conducted at a large dairy farm in Oita Prefecture in Japan. Experimental results show that the proposed method has promise in practical applications. In particular, we found that the high frequency of posture changes has played a central role in accurately predicting the time of calving.

Weak Instability of Chen–Ricles Explicit Method for Structural Dynamics

2018 ◽  
Vol 13 (5) ◽  
Author(s):  
Shuenn-Yih Chang
Keyword(s):  
Steady State ◽  
Nonlinear Systems ◽  
High Frequency ◽  
Explicit Method ◽  
Order Accuracy ◽  
Practical Applications ◽  
Correction Scheme ◽  
Highly Nonlinear ◽  
Steady State Responses ◽  
State Responses

Although the Chen–Ricles (CR) explicit method (CRM) (proposed by Chen and Ricles) has been claimed to have desired numerical properties, such as unconditional stability, explicit formulation, and second-order accuracy, it also shows some unusual properties, such as a less accuracy of solving highly nonlinear systems, a high-frequency overshoot in steady-state responses, and a weak instability. A correction scheme by adjusting the displacement difference equation with a loading term can be employed to extinguish the high-frequency overshoot in steady-state responses. However, there is still no way to get rid of the weak instability and to improve the less accuracy of solving highly nonlinear systems. It is recognized that a weak instability might result in inaccurate solutions or numerical explosions. Hence, the practical applications of CRM are strictly limited.

Dielectric Heating Sensitizers for Processing of Polymers

1988 ◽  
Vol 124 ◽  
Author(s):  
Agmund K. Thorsrud
Keyword(s):  
High Frequency ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Polyphenylene Sulfide ◽  
Dielectric Heating ◽  
Practical Applications ◽  
Ultrahigh Molecular Weight ◽  
Fine Particle Size ◽  
The Many ◽  
Thermoplastic Resins ◽  
Polymer Type

ABSTRACTMicrowave heating has for years been successfully used for some polymer applications, especially in preheating or continous vulcanization of rubber and also for crosslinking of thermosets. It may therefore seem surprising to find how little woork has been reported on the use of dielectric heating of thermoplastic resins. Certainly a major reason is that very few thermoplastics have dielectric properties making them respond to high frequency electromagnetic fields, or their response is inadequate for practical applications.Many processes could benefit from the many advantages of dielectric heating if the most suitable polymer could be made to absorb such energy. Therefore a study was undertaken to find additives which in small amounts could render virtually all polymers, especially the thermoplastic ones, responsive to microwave or radio frequency electromagnetic energy without significantly changing processing and physical properties.A series of such sensitizers was developed. Some of these are now commercially available as white, fine particle size, freeflowing powders and others are colorless liquids. Their use will depend on polymer type and application, but their common objective is to substantially increase the material's loss factor.Selected tests with difficult to process ultrahigh molecular weight polyethylene (UHWPE) and polyphenylene sulfide (PPS) proved that the sensitizers in low concentration will allow dielectric heating of unresponsive polymers with potential for important advantages in cost and quality.

Unlocking diamond's potential as an electronic material

2007 ◽  
Vol 366 (1863) ◽  
pp. 251-265 ◽  
Author(s):  
R.S Balmer ◽  
I Friel ◽  
S.M Woollard ◽  
C.J.H Wort ◽  
G.A Scarsbrook ◽  
...  
Keyword(s):  
High Frequency ◽  
High Performance ◽  
Synthetic Diamond ◽  
Electronic Devices ◽  
Current Status ◽  
Small Signal ◽  
Practical Applications ◽  
A Current ◽  
Rf Measurements

In this paper, we review the suitability of diamond as a semiconductor material for high-performance electronic applications. The current status of the manufacture of synthetic diamond is reviewed and assessed. In particular, we consider the quality of intrinsic material now available and the challenges in making doped structures suitable for practical devices. Two practical applications are considered in detail. First, the development of high-voltage switches capable of switching voltages in excess of 10 kV. Second, the development of diamond MESFETs for high-frequency and high-power applications. Here device data are reported showing a current density of more than 30 mA mm −1 along with small-signal RF measurements demonstrating gigahertz operation. We conclude by considering the remaining challenges which will need to be overcome if commercially attractive diamond electronic devices are to be manufactured.

scholarly journals A sharp relative-error bound for the Helmholtz h-FEM at high frequency

2021 ◽  
Author(s):  
D. Lafontaine ◽  
E. A. Spence ◽  
J. Wunsch
Keyword(s):  
Plane Wave ◽  
Relative Error ◽  
High Frequency ◽  
Wave Scattering ◽  
Scattering Problem ◽  
Practical Applications ◽  
Polynomial Degree ◽  
Fixed Order ◽  
Explicit Bounds ◽  
Plane Wave Scattering

AbstractFor the h-finite-element method (h-FEM) applied to the Helmholtz equation, the question of how quickly the meshwidth h must decrease with the frequency k to maintain accuracy as k increases has been studied since the mid 80’s. Nevertheless, there still do not exist in the literature any k-explicit bounds on the relative error of the FEM solution (the measure of the FEM error most often used in practical applications), apart from in one dimension. The main result of this paper is the sharp result that, for the lowest fixed-order conforming FEM (with polynomial degree, p, equal to one), the condition “$$h^2 k^3$$ h 2 k 3 sufficiently small" is sufficient for the relative error of the FEM solution in 2 or 3 dimensions to be controllably small (independent of k) for scattering of a plane wave by a nontrapping obstacle and/or a nontrapping inhomogeneous medium. We also prove relative-error bounds on the FEM solution for arbitrary fixed-order methods applied to scattering by a nontrapping obstacle, but these bounds are not sharp for $$p\ge 2$$ p ≥ 2 . A key ingredient in our proofs is a result describing the oscillatory behaviour of the solution of the plane-wave scattering problem, which we prove using semiclassical defect measures.

scholarly journals Vibrational convection in a heterogeneous binary mixture. Part 1. Time-averaged equations

2019 ◽  
Vol 870 ◽  
pp. 543-562 ◽  
Author(s):  
Anatoliy Vorobev ◽  
Tatyana Lyubimova
Keyword(s):  
High Frequency ◽  
Stokes Equations ◽  
Concentration Field ◽  
Multiphase System ◽  
Short Time Scale ◽  
Practical Applications ◽  
Two Fluids ◽  
Vibrational Convection ◽  
High Frequency Vibrations ◽  
Averaged Model

High-frequency vibrations of a container filled with a fluid generate pulsation flows that however are barely visible with the naked eye, and induce the slow but large-amplitude averaged flows that are important for various practical applications. In this work we derive a theoretical model that gives the averaged description of the influence of uniform high-frequency vibrations on an isothermal mixture of two slowly miscible liquids. The miscible multiphase system is described within the framework of the phase-field approach. The full Cahn–Hillard–Navier–Stokes equations are split into the separate systems for the quasi-acoustic, pulsating and averaged flow fields, eliminating the need for the resolution of the short time scale pulsation motion and thus making the analysis of the long-term evolution much more efficient. The resultant averaged model includes the effects of concentration diffusion and barodiffusion, the dynamic interfacial stresses and the generation of the hydrodynamic flows by non-homogeneities of the concentration field (when they are combined with the effects of gravity and vibrations). The resultant model for the vibrational convection in a heterogeneous mixture of two fluids separated by diffusive boundaries could be used for the description of processes of mixing/de-mixing, solidification/melting, polymerisation, etc. in the presence of vibrations.

scholarly journals Recent advances in threshold-dependent gene drives for mosquitoes

2018 ◽  
Vol 46 (5) ◽  
pp. 1203-1212 ◽  
Author(s):  
Philip T. Leftwich ◽  
Matthew P. Edgington ◽  
Tim Harvey-Samuel ◽  
Leonela Z. Carabajal Paladino ◽  
Victoria C. Norman ◽  
...  
Keyword(s):  
High Frequency ◽  
Gene Drive ◽  
Fitness Costs ◽  
Practical Applications ◽  
Disease Vector ◽  
Recent Advances ◽  
Mathematical Analyses ◽  
Global Eradication ◽  
Gene Drives

Mosquito-borne diseases, such as malaria, dengue and chikungunya, cause morbidity and mortality around the world. Recent advances in gene drives have produced control methods that could theoretically modify all populations of a disease vector, from a single release, making whole species less able to transmit pathogens. This ability has caused both excitement, at the prospect of global eradication of mosquito-borne diseases, and concern around safeguards. Drive mechanisms that require individuals to be released at high frequency before genes will spread can therefore be desirable as they are potentially localised and reversible. These include underdominance-based strategies and use of the reproductive parasite Wolbachia. Here, we review recent advances in practical applications and mathematical analyses of these threshold-dependent gene drives with a focus on implementation in Aedes aegypti, highlighting their mechanisms and the role of fitness costs on introduction frequencies. Drawing on the parallels between these systems offers useful insights into practical, controlled application of localised drives, and allows us to assess the requirements needed for gene drive reversal.

Synthesis and Microwave Absorption Properties of Co2Z Barium Ferrite by Salt-Molten Method

2010 ◽  
Vol 160-162 ◽  
pp. 957-961
Author(s):  
Jun Li Zhang ◽  
Bo Chong Wang ◽  
Zhi Wei Li ◽  
Liang Qiao ◽  
Tao Wang ◽  
...  
Keyword(s):  
Reflection Loss ◽  
High Frequency ◽  
Barium Ferrite ◽  
Single Phase ◽  
Microwave Measurement ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Practical Applications ◽  
Environmentally Friendly Method

In this work, the Z-type barium ferrite of single phase was prepared by the salt-molten method which was a novel, economical and environmentally friendly method. The results showed that the salt was helpful to get single phase and could effectively modify the shape of the powder. Based on the microwave measurement, reflection losses exceeding −20 dB of Co2Z composite were obtained in the frequency range of 4.1–14.5 GHz for absorber thicknesses of 2.1–3.5 mm and the minimum value of the reflection loss was -42.9 dB at 4.9 GHz for the thickness of 2.9 mm. For those unique properties, Co2Z could be a good candidate for electromagnetic (EM) materials and other practical applications at the high frequency.

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