Positional targets for lingual consonants defined using electromagnetic articulography

The study examined the positional targets for lingual consonants defined using a point-parameterized approach with Wave (NDI, Waterloo, ON, Canada). The overall goal was to determine which consonants had unique tongue positions with respect to other consonants. Nineteen talkers repeated vowel-consonant-vowel (VCV) syllables that included consonants /t, d, s, z, , k, g/ in symmetrical vowel contexts /i, u, a/, embedded in a carrier phrase. Target regions for each consonant, characterized in terms of x,y,z tongue positions at the point of maximum tongue elevation, were extracted. Distances and overlaps were computed between all consonant pairs and compared to the distances and overlaps of their contextual targets. Cognates and postalveolar homorganics were found to share the location of their target regions. On average, alveolar stops showed distinctively different target regions than alveolar fricatives, which in turn showed different target region locations than the postalveolar consonants. Across talker variability in target locations was partially explained by differences in habitual speaking rate and hard palate characteristics.     

Three-dimensional relativistic electromagnetic subcycle solitons

Three-dimensional (3D) relativistic electromagnetic subcycle solitons were observed in 3D particle-in-cell simulations of an intense short-laser-pulse propagation in an underdense plasma. Their structure resembles that of an oscillating electric dipole with a poloidal electric field and a toroidal magnetic field that oscillate in phase with the electron density with frequency below the Langmuir frequency. On the ion time scale, the soliton undergoes a Coulomb explosion of its core, resulting in ion acceleration, and then evolves into a slowly expanding quasineutral cavity.     

Three-dimensional electromagnetic PIC model of a compact ECR plasmasource

A three-dimensional electromagnetic particle-in-cell (PIC) model is developed and used to model a compact ECR plasma source. The finite-difference time-domain (FDTD) technique is used to model the microwave fields which excite the plasma at 2.45 GHz. The PIC technique is used to model the dynamics of both the electrons and ions in the plasma. The grid structure used is constructed using the cylindrical coordinate system. Techniques which permit stable numerical solutions in the cylindrical coordinate system are developed and described. The electromagnetic fields and the plasma dynamics are solved in a self-consistent manner. A compact ECR (electron cyclotron resonance) plasma source used for the generation of ions for materials processing is simulated. This source has a plasma size of 3.6 cm in diameter and 3 cm in height. Simulation results of microwave power absorption, plasma potential, and microwave electric fields are presented. Distributed computing techniques are explored to handle the large computer memory requirements and the long computer simulation times associated with the three-dimensional particle-in-cell plasma model     

电磁感应式液固态金属电阻率定性测量装置及应用

介绍了一种自主研制的非接触式电阻率测量装置,该装置基于电磁感应原理,可实现降温过程中金属从液态到固态各阶段电阻率的定性测量,为实时表征金属材料的结构变化提供了一种有效的测量工具.详细介绍了该装置的设计原理及其结构,同时利用该装置,测量了金属Zn,Sb以及过共晶Zn-70 wt.% Sb合金降温过程中电阻率随温度的变化情况,验证了该装置的可靠性. 关键词： 电阻率 电磁感应 液态金属 结构转变     

Elastic wave interactions as a principle of vibration measurement

It is known that ultrasound can be used to measure the constant in time deformations and residual stresses, through the acoustoelasticity effect. The method presented here is different from this principle. It is based on the non-resonant parametric interaction of elastic waves and enables measurement of the dynamic deformation in elastic media. The aim of this work is to investigate the interaction of waves in non-linear elastic media with the deformation fields in parametric approximation and to create a method that permits observation (in three-dimensions) of the dynamic stress-state of the opaque elements of a structure. In particular, interest in the solution of this problem arises for high-frequency non-stationary loading on the structure, when it is impossible to determine the internal stress-state of the elastic body by measurement of the vibration of its surface. The solution to this is found by using ultrasonic waves as a type of transducer that can freely penetrate the elastic body in the necessary direction.     

三维电磁粒子模拟并行计算的研究

三维电磁粒子模拟基于时域有限差分算法（FDTD）和PIC（particle-in-cell）方法.根据FDTD和PIC方法的特点,可以将整个模拟区域分割为多个子区域,每个计算进程模拟计算一个子区域,通过消息传递交换子区域的边界数据从而实现并行计算这一基本思路,完成了并行算法的设计,并分析了并行加速比的影响因素.在三维电磁粒子模拟软件CHIPIC3D上实现了该并行算法并验证了算法的正确性,最后应用CHIPIC3D并行版本对磁绝缘线振荡器和相对论速调管两种典型的高功率微波源器件进行了模拟,证明了该并行算法能取 关键词： 电磁粒子模拟 时域有限差分 并行计算 高功率微波源     

Nondemolition principle of quantum measurement theory

We give an explicit axiomatic formulation of the quantum measurement theory which is free of the projection postulate. It is based on the generalized nondemolition principle applicable also to the unsharp, continuous-spectrum and continuous-in-time observations. The collapsed state-vector after the objectification is simply treated as a random vector of the a posterioristate given by the quantum filtering, i.e., the conditioning of the a prioriinduced state on the corresponding reduced algebra. The nonlinear phenomenological equation of continuous spontaneous localization has been derived from the Schrödinger equation as a case of the quantum filtering equation for the diffusive nondemolition measurement. The quantum theory of measurement and filtering suggests also another type of the stochastic equation for the dynamical theory of continuous reduction, corresponding to the counting nondemolition measurement, which is more relevant for the quantum experiments.     

An analysis of the principle of minimal electromagnetic interaction

The meaning and contents of the principle of minimal electromagnetic interactions are analyzed in the framework of the classical electrodynamics of a point charged particle. The essence of this analysis consists in expressing the free electromagnetic field as a difference of retarded and advanced fields and in observing the effect of switching on the minimal coupling on the retarded field. A new equivalent formulation of this principle is given and the possibility of its generalization is suggested.Dedicated to Professor V. Votruba on his sixtieth birthday.     

Three-dimensional optical measurement of instantaneous pressure

Local perturbations in material density induced in a material by a compressional wave give rise to local perturbations in refractive index. Accurate, high-resolution, three-dimensional, optical measurements of an instantaneous refractive index perturbation in a homogeneous, optically transparent medium may be obtained from measurements of scattered optical intensity alone. The method of generalized projections allows incorporation of optical intensity measurements into an iterative algorithm for computing the phase of the interrogating optical pulse as the solution of a fixed point equation. The complex optical field amplitude, computed in this manner, is unique up to a constant unit magnitude complex coefficient. The three-dimensional refractive index distribution may be computed via the Fourier slice reconstruction algorithm from the optical phase data under the assumption of weak optical scattering. The refractive index perturbation is related to local instantaneous pressure under a linear, small-displacement model for the mechanical wave. A numerical simulation of the measurement experiment, phase recovery, and reconstruction process for a plane piston ultrasound transducer with a semicircular aperture and center frequency of 1.5 MHz is described and corresponds very well with experiment. Experimental data obtained using an 810-nm laser source are used to reconstruct the three-dimensional pressure field from two elements of a 2.5-MHz linear array. Comparison with a measurement obtained via a 500-microm needle hydrophone shows excellent agreement.     

Three-dimensional bubbly flow measurement using PIV

The experimental flow visualization tool, Particle Image Velocimetry (PIV), is being extended to determine the velocity fields in three-dimensional, two-phase fluid flows. In the past few years, the technique has attracted quite a lot of interest. PIV enables fluid velocities across a region of a flow to be measured at a single instant in time in the whole volume (global) of interest. This instantaneous velocity profile of a given flow field is determined by digitally recording particle (microspheres or bubbles) images within the flow over multiple successive video frames and then conducting flow pattern identification and analysis of the data. This paper presents instantaneous velocity measurements in various three-dimensional, bubbly two-phase flow situations. This information is useful for developing or improving existing computer constitutive models that simulate this type of flow field. It is also useful for understanding the detailed structure of two-phase flows.     

Three-dimensional computer modeling of electromagnetic fields: A global lookback lattice truncation scheme

A new lattice truncation scheme for the finite difference time domain approach to the solution of Maxwell's equations has been developed. The problem space is truncated near the sources and the field components on its boundary are generated from those field values known at retarded times on an interior surface one cell from it with an integral representation of the electromagnetic field. The numerical implementation of this global lookback scheme is discussed. Examples which have been used to determine its characteristics and its validity are given.     

Gravitation in a plane space. Equivalence principle for bulk bodies of electromagnetic structure

In a previous paper [1] the author proposed a new linear nonmetric theory of gravitation in a plane space by giving the Einstein values for the four effects of the general theory of relativity (GTR). The field and motion equations were constructed on the basis of Lagrangians selected by the Hamilton principle. The gravitational field potential (GF) was a symmetric tensor of the second rank . A nonlinear extension of the theory is carried out in this paper on the basis of a single Lagrangian of the GF interaction with matter f T + T, where T is the energy-momentum tensor of matter including the GF, f and are arbitrary constants of the theory. Within the framework of the nonlinear theory which yields the Einstein values for the four GTR effects, an additional condition is obtained which is imposed on the five arbitrary constants of the theory from which the satisfiability of the weak equivalence principle for bulk bodies of electromagnetic structure follows.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 114–122, October, 1978.The author is grateful to Prof. D. D. Ivanenko for attention to the research and for valuable remarks, and to the participants of the seminar he leads for discussing the paper.     

Crack velocity measurement by induced electromagnetic radiation

Our model of electromagnetic radiation (EMR) emanated from fracture implies that EMR amplitude is proportional to crack velocity. Soda lime glass samples were tested under uniaxial tension. Comparison of crack velocity observed by Wallner line analysis and the peak amplitude of EMR signals registered during the test, showed very good correlation, validating this proportionality.     

Three-dimensional position measurement of a levitated nanoparticle in a vacuum by a Dove prism

Forward-scattering-light interferometry has become the most commonly used position detection scheme in optical levitation systems. Usually, three-set detectors are required to obtain the three-dimensional motion information. Here, we simplify the three-set detectors to one set by inserting a Dove prism. We investigate the role of a Dove prism in the position measurement process with an optical levitation system in vacuum. The relationship between the power spectral density and the rotation angle of a Dove prism is experimentally demonstrated and analyzed. This work shows that the Dove prism can greatly reduce the complexity of the experimental setup, which can be applied to compact optical levitation systems for studies in metrology, quantum physics,and biology.     

三维电磁扩散场数值模拟及磁化效应的影响

采用矢量有限元法实现了三维电磁扩散场数值模拟,并成功将其应用在大地电磁的正演研究中.为灵活精确地拟合起伏地形和地下不规则构造,采用由不规则四面体单元组成的非结构化网格,可根据模型设计的需要调整网格的大小.引入了基于二次场理论,将解析的一次场从总场中扣除,直接计算二次场,使得误差仅局限于相对较小的二次场,以提高总场计算精度.常规的节点有限元法不满足电性分界面上法向电场不连续和无源区单元内电流密度无散,违反麦克斯韦方程组.为克服节点有限元法的弊端,使用矢量有限元法求解基于二次电场的偏微分方程.另外,在算法设计中,考虑了磁导率参数的变化,可以模拟磁导率不均匀的模型.通过与COMMEMI模型已发表的结果对比,证明了本文算法的正确性和精确性.为突显非结构网格优势,计算了椭球异常体模型和任意地形模型的MT响应,并详细讨论了地形和磁化效应对三维数值模拟结果的影响.     

Three-dimensional electromagnetic band-gap structure containing TiO2 fabricated by rapid-prototyping

Three-dimensional (3D) diamond structure electromagnetic band-gap (EBG) structures containing TiO₂ fabricated by rapid-prototyping (RP) technique were investigated. The simulations based on finite element method (FEM) were employed to model the band structures. The influence of aspect ratio on the band gap width was studied. The optimal band gap width EBGs were fabricated and investigated experimentally. Gel-casting together with RP technique were used in the fabrication. TiO₂ gel was cast into the diamond structure molds fabricated by RP method to obtain the green EBG structures. The transmission characteristics of the EBG structures were measured by transmission/reflection (T/R) methods using a vector network analyzer. Complete band-gap was observed in the transmission characteristics in the frequency from 11 GHz to 12 GHz, which agreed well with the simulation results.     

声速测量实验原理讨论

对空气中声速测量实验原理进行了讨论,考虑了空气对声波的吸收,分别用平面波和球面波表示发射探头和接收探头之间的声波,导出了接收声压的表达式,分析了声压随探头间距的变化规律.结果表明,尽管声场不是理想驻波,但声压极值随探头间距按半波长周期性的变化规律与驻波共振原理得到的结论相一致,然而3种原理在解释接收声压幅值衰减规律时存在差异,其中球面波原理与实验现象最吻合.