Measurement of Microwave Induced Forces

1992 ◽  
Vol 269 ◽  
Author(s):  
John L. Watkins ◽  
H. W. Jackson ◽  
M. Barmatz
Keyword(s):  
Electric Field ◽  
Stable Equilibrium ◽  
Resonant Cavity ◽  
Single Mode ◽  
Microgravity Environment ◽  
Force Measurements ◽  
Stable Equilibrium Position ◽  
Infinite Set ◽  
Frequency Radiation ◽  
Made In

ABSTRACTElectrically polarizable materials in an inhomogeneous electric field experience a dielectrophoretic force which is proportional to the gradient of the square of the electric field. For high frequency radiation, the time averaged electromagnetic field provides a dc force. The force exerted on a sapphire and a metal sphere by the microwave field in a single mode resonant cavity has been measured. The force measurements have been made at equally spaced points along three orthogonal axes centered in a cylindrical cavity operating in the TE111 mode using 20 watts of microwave power at about 4.84 GHz. These data are compared to the simple theory of dielectrophoresis on a small sphere and verify that, for this mode and in the absence of other forces, there is a unique and stable equilibrium position at the center of the cavity. Measurements of the quality factor of the cavity provide a means of making an absolute check to the theory. The TE111 mode is one of an infinite set of modes predicted to have stable equilibrium positions that exist away from the cavity walls. It is proposed that dielectrophoresis in a microwave resonant cavity can be used to position samples for material processing applications in a microgravity environment. Knowledge of these forces may also be important for interpreting thermogravimetric measurements made in a microwave oven.

Bubble motion in liquid nitrogen under a non-uniform electric field in a microgravity environment

1997 ◽  
Vol 117 (11) ◽  
pp. 1109-1114
Author(s):  
Yoshiyuki Suda ◽  
Kenji Mutoh ◽  
Yosuke Sakai ◽  
Kiyotaka Matsuura ◽  
Norio Homma
Keyword(s):  
Electric Field ◽  
Liquid Nitrogen ◽  
Microgravity Environment ◽  
Uniform Electric Field ◽  
Bubble Motion

scholarly journals High-speed operation of single-mode tunable quantum cascade laser based on ultra-short resonant cavity

AIP Advances ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 015325
Author(s):  
Yuhong Zhou ◽  
Junqi Liu ◽  
Shenqiang Zhai ◽  
Ning Zhuo ◽  
Jinchuan Zhang ◽  
...  
Keyword(s):  
Quantum Cascade Laser ◽  
High Speed ◽  
Resonant Cavity ◽  
Single Mode ◽  
Quantum Cascade

scholarly journals Research on Electromagnetic Sensitivity Properties of Sodium Chloride during Microwave Heating

2020 ◽  
Vol 39 (1) ◽  
pp. 54-62
Author(s):  
Hua Chen ◽  
Junjiang Chen ◽  
Weijun Wang ◽  
Huan Lin
Keyword(s):  
Sodium Chloride ◽  
Electric Field ◽  
Water Content ◽  
Heating Rate ◽  
Microwave Heating ◽  
Resonant Cavity ◽  
Relative Dielectric Constant ◽  
Heating System ◽  
Heating Process ◽  
Heating Efficiency

AbstractThe multimode resonant cavity is the most common cavity. The material often shows on selective heating performance during the heating process due to the effect of microwave heating having a closely relationship with the electromagnetism parameters. This paper is based on finite difference time domain method (FDTD) to establish the electromagnetic-thermal model. The electromagnetic sensitivity property parameters of sodium chloride including relative dielectric constant, loss angle tangent and water content of sodium chloride is studied during the heating and drying process. The heating rate and the electric field distribution of sodium chloride, at the different water content, were simulated with the electromagnetic characteristic parameters changing. The results show that with the electromagnetic sensitivity property parameters varying, the electric field strength, heating rate and steady-state temperature of the heating material will all have a variety in the cavity. Some measures are proposed to improve the heating efficiency and ensure the stability of the microwave heating system in the industrial application.

Cavity Effects and Hot Spot Formulation Inmicrowave Heated Ceramic Fibers

1996 ◽  
Vol 430 ◽  
Author(s):  
G. A. Kriegsmann
Keyword(s):  
Electric Field ◽  
Hot Spots ◽  
Hot Spot ◽  
Single Mode ◽  
Uniform Electric Field ◽  
Ceramic Fibers ◽  
Entire Sample ◽  
Mathematical Equations ◽  
Cavity Effects ◽  
Ceramic Cylinder

AbstractRecently the heating of a thin ceramic cylinder in a single mode applicator was modeled and analyzed assuming a small Biot number and a known uniform electric field through out the sample. The resulting simplified mathematical equations explained the mechanism for the generation and growth of localized regions of high temperature. The results predicted that a hot-spot, once formed, will grow until it consumes the entire sample. Most experimental observations show that the hot-spot stabilizes and moves no further.A new model is proposed which incorporates the effect of the cavity and the nlonuiniform character of the electric field along the axis of the sample. The resulting simplified mathematical equations indicate that these effects stabilize the growth of hot-spots.

On the Senftleben-Beenakker Electric Effect in Gaseous Ammonia

1971 ◽  
Vol 26 (6) ◽  
pp. 952-964 ◽  
Author(s):  
A.C. Levi ◽  
G.E. Tommei
Keyword(s):  
Electric Field ◽  
Field Dependence ◽  
Gaseous Ammonia ◽  
Homogeneous Electric Field ◽  
Distribution Matrix ◽  
Electric Effect ◽  
Low Pressures ◽  
Infinite Set

Abstract The viscosity of gaseous ammonia in the presence of a static homogeneous electric field is calculated using the Waldmann-Snider equation. Special attention is paid to the field dependence of the effect which is strongly influenced by molecular inversion. The latter causes a coupling of tensors of different rank in J in the expansion of the distribution matrix, thereby leading to an infinite set of equations which is solved numerically by a limiting procedure. The effect has a complicated dependence on pressure p and field E but to a good approximation turns out to depend on E/p a t pressures high with respect to an inversion pressure (about 5 atm for NH3, 300 torr for ND3) and, in agreement with the experiments, on E2/p at low pressures.

scholarly journals The assessment of electromagnetic field radiation exposure for mobile phone users

2014 ◽  
Vol 71 (12) ◽  
pp. 1138-1143 ◽  
Author(s):  
Raimondas Buckus ◽  
Birute Strukcinskiene ◽  
Juozas Raistenskis
Keyword(s):  
Electromagnetic Field ◽  
Field Strength ◽  
Electric Field ◽  
Mobile Phone ◽  
Radiation Exposure ◽  
Electric Field Strength ◽  
Rural Area ◽  
Mobile Phones ◽  
Field Radiation ◽  
Made In

Background/Aim. During recent years, the widespread use of mobile phones has resulted in increased human exposure to electromagnetic field radiation and to health risks. Increased usage of mobile phones at the close proximity raises questions and doubts in safety of mobile phone users. The aim of the study was to assess an electromagnetic field radiation exposure for mobile phone users by measuring electromagnetic field strength in different settings at the distance of 1 to 30 cm from the mobile user. Methods. In this paper, the measurements of electric field strength exposure were conducted on different brand of mobile phones by the call-related factors: urban/rural area, indoor/outdoor setting and moving/stationary mode during calls. The different types of mobile phone were placed facing the field probe at 1 cm, 10 cm, 20 cm and 30 cm distance. Results. The highest electric field strength was recorded for calls made in rural area (indoors) while the lowest electric field strength was recorded for calls made in urban area (outdoors). Calls made from a phone in a moving car gave a similar result like for indoor calls; however, calls made from a phone in a moving car exposed electric field strength two times more than that of calls in a standing (motionless) position. Conclusion. Electromagnetic field radiation depends on mobile phone power class and factors, like urban or rural area, outdoor or indoor, moving or motionless position, and the distance of the mobile phone from the phone user. It is recommended to keep a mobile phone in the safe distance of 10, 20 or 30 cm from the body (especially head) during the calls.

An Edge Dislocation in a Three-Phase Composite Cylinder Model

1991 ◽  
Vol 58 (1) ◽  
pp. 75-86 ◽  
Author(s):  
H. A. Luo ◽  
Y. Chen
Keyword(s):  
Edge Dislocation ◽  
Stable Equilibrium ◽  
Phase Model ◽  
Composite Cylinder ◽  
Two Phase ◽  
Trapping Mechanism ◽  
Three Phase ◽  
Cylinder Model ◽  
Stable Equilibrium Position ◽  
The Stability

An exact solution is given for the stress field due to an edge dislocation embedded in a three-phase composite cylinder. The force on the dislocation is then derived, from which a set of simple approximate formulae is also suggested. It is shown that, in comparison with the two-phase model adopted by Dundurs and Mura (1964), the three-phase model allows the dislocation to have a stable equilibrium position under much less stringent combinations of the material constants. As a result, the so-called trapping mechanism of dislocations is more likely to take place in the three-phase model. Also, the analysis and calculation show that in the three-phase model the orientation of Burgers vector has only limited influence on the stability of dislocation. This behavior is pronouncedly different from that predicted by the two-phase model.

The Stress Field Due to an Edge Dislocation Interacting With Two Circular Inclusions

2016 ◽  
Vol 33 (2) ◽  
pp. 161-172 ◽  
Author(s):  
C.-K. Chao ◽  
F.-M. Chen ◽  
T.-H. Lin
Keyword(s):  
Stable Equilibrium ◽  
Complex Stress ◽  
Explicit Dependence ◽  
Closed Form Solutions ◽  
General Series ◽  
Stable Equilibrium Position ◽  
Arbitrary Plane ◽  
Plane Elastostatics ◽  
Combination Of Material ◽  
Extended Matrix

AbstractA general series solution to the problem of interacting circular inclusions in plane elastostatics is presented in this paper. The analysis is based on the use of the complex stress potentials of Muskhelishvili and the theorem of analytical continuation. The general forms of the complex potentials are derived explicitly for the circular inhomogeneities under arbitrary plane loading. Using the alternation technique, these general expressions were subsequently employed to treat the problem of an infinitely extended matrix containing two arbitrarily located inhomogeneities. The major contribution of the present proposed method is shown to be capable of yielding approximate closed-form solutions for multiple inclusions, thus providing the explicit dependence of the solution on the pertinent parameters. The result shows that the dislocation has a stable equilibrium position at a certain combination of material constants. The case of an inhomogeneity interacting with a circular hole under a remote uniform load is also investigated.

scholarly journals Kingman’s Model with Random Mutation Probabilities: Convergence and Condensation II

2020 ◽  
Vol 181 (3) ◽  
pp. 870-896
Author(s):  
Linglong Yuan
Keyword(s):  
Explicit Expression ◽  
Stable Equilibrium ◽  
Matrix Representation ◽  
Random Model ◽  
Random Mutation ◽  
Fitness Level ◽  
Positive Proportion ◽  
Fitness Value ◽  
Globally Stable ◽  
Made In

Abstract A generalisation of Kingman’s model of selection and mutation has been made in a previous paper which assumes all mutation probabilities to be i.i.d.. The weak convergence of fitness distributions to a globally stable equilibrium was proved. The condensation occurs if almost surely a positive proportion of the population travels to and condensates on the largest fitness value due to the dominance of selection over mutation. A criterion of condensation was given which relies on the equilibrium whose explicit expression is however unknown. This paper tackles these problems based on the discovery of a matrix representation of the random model. An explicit expression of the equilibrium is obtained and the key quantity in the condensation criterion can be estimated. Moreover we examine how the design of randomness in Kingman’s model affects the fitness level of the equilibrium by comparisons between different models. The discovered facts are conjectured to hold in other more sophisticated models.

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