Application-specific parameterization of reduced order equivalent circuit battery models for improved accuracy at dynamic load

Reduced order equivalent circuit battery models are widely used for modeling batteries as a part of complex system or as a basis for battery monitoring algorithms. These models are often parameterized in frequency domain using impedance spectroscopy or in time domain by applying current profile and measuring respective voltage response. This paper shows how the frequency characteristic of a typical battery load in a given application can be considered during parameterization to improve the accuracy of the model when it is used in this application with dynamic load. The method uses impedance-based parameterization technique by adopting additional weighting coefficients to the complex nonlinear least squares (CNLS) fitting procedure without introducing any restrictions on its applicability. As an example, modeling of lithium-ion battery in electric vehicles is considered. The proposed techniques reduce the inaccuracy of modeled dynamic battery voltage response by 40% in the considered example.     

Molecular beam epitaxy of alternating-strain ZnSe-based multilayer heterostructures for blue-green lasers

High-quality ZnSe-based heterostructures are grown by uninterrupted molecular beam epitaxy using the concept of strain compensation and alternating-strain multilayers. To verify the advantages of this technique, optically pumped ZnSSe/ZnCdSe laser structures containing short-period superlattices or multiple quantum wells have been grown and studied. A room-temperature injection laser diode with a BeZnSe/ZnSe superlattice waveguide is described. Fiz. Tekh. Poluprovodn. 32, 1272–1276 (October 1998)     

The effect of abdominal wall morphology on ultrasonic pulse distortion. Part II. Simulations

Wavefront propagation through the abdominal wall was simulated using a finite-difference time-domain implementation of the linearized wave propagation equations for a lossless, inhomogeneous, two-dimensional fluid as well as a simplified straight-ray model for a two-dimensional absorbing medium. Scanned images of six human abdominal wall cross sections provided the data for the propagation media in the simulations. The images were mapped into regions of fat, muscle, and connective tissue, each of which was assigned uniform sound speed, density, and absorption values. Propagation was simulated through each whole specimen as well as through each fat layer and muscle layer individually. Wavefronts computed by the finite-difference method contained arrival time, energy level, and wave shape distortion similar to that in measurements. Straight-ray simulations produced arrival time fluctuations similar to measurements but produced much smaller energy level fluctuations. These simulations confirm that both fat and muscle produce significant wavefront distortion and that distortion produced by fat sections differs from that produced by muscle sections. Spatial correlation of distortion with tissue composition suggests that most major arrival time fluctuations are caused by propagation through large-scale inhomogeneities such as fatty regions within muscle layers, while most amplitude and waveform variations are the result of scattering from smaller inhomogeneities such as septa within the subcutaneous fat. Additional finite-difference simulations performed using uniform-layer models of the abdominal wall indicate that wavefront distortion is primarily caused by tissue structures and inhomogeneities rather than by refraction at layer interfaces or by variations in layer thicknesses.     

双参数获取多功能控制器

双参数获取多功能控制器是一个单宽度NIM插件,与三个ADC,IBM微机及接口连接组成双参数获取多功能微机多道。它的功能分三部分:(1)双参数获取 全谱为256×256,利用开窗技术分区域获取可达512×512,1024×1024。(2)单谱 两个单路可同时获取。(3)谱定标(又称多谱获取)可用范围:单向 1024道×8,0048道×4;双向2×1024道×4,2×512道×8。     

Finite element modeling and experimental proof of NEMS-based silicon pillar resonators for nanoparticle mass sensing applications

The potential use of nanoelectromechanical systems (NEMS) created in silicon nanopillars (SiNPLs) is investigated in this work as a new generation of aerosol nanoparticle (NP)-detecting device. The sensor structures are created and simulated using a finite element modeling (FEM) tool of COMSOL Multiphysics 4.3b to study the resonant characteristics and the sensitivity of the SiNPL for femtogram NP mass detection in 3-D structures. The SiNPL arrays use a piezoelectric stack for resonance excitation. To achieve an optimal structure and to investigate the etching effect on the fabricated resonators, SiNPLs with different designs of meshes, sidewall profiles, heights, and diameters are simulated and analyzed. To validate the FEM results, fabricated SiNPLs with a high aspect ratio of approximately 60 are used and characterized in resonant frequency measurements where their results agree well with those simulated by FEM. Furthermore, the deflection of a SiNPL can be enhanced by increasing the applied piezoactuator voltage. By depositing different NPs [i.e., gold (Au), silver (Ag), titanium dioxide (TiO₂), silicon dioxide (SiO₂), and carbon black NPs] on the SiNPLs, the decrease of the resonant frequency is clearly shown confirming their potential to be used as airborne NP mass sensor with femtogram resolution level. A coupling concept of the SiNPL arrays with piezoresistive cantilever resonator in terms of the mass loading effect is also studied concerning the possibility of obtaining electrical readout signal from the resonant sensors.     

Thermoelectric Properties of High-Doped Silicon from Room Temperature to 900 K

Silicon is investigated as a low-cost, Earth-abundant thermoelectric material for high-temperature applications up to 900 K. For the calculation of module design the Seebeck coefficient and the electrical as well as thermal properties of silicon in the high-temperature range are of great importance. In this study, we evaluate the thermoelectric properties of low-, medium-, and high-doped silicon from room temperature to 900 K. In so doing, the Seebeck coefficient, the electrical and thermal conductivities, as well as the resulting figure of merit ZT of silicon are determined.     

Reduction of variance in spectral estimates for correction of ultrasonic aberration

A variance reduction factor is defined to describe the rate of convergence and accuracy of spectra estimated from overlapping ultrasonic scattering volumes when the scattering is from a spatially uncorrelated medium. Assuming that the individual volumes are localized by a spherically symmetric Gaussian window and that centers of the volumes are located on orbits of an icosahedral rotation group, the factor is minimized by adjusting the weight and radius of each orbit. Conditions necessary for the application of the variance reduction method, particularly for statistical estimation of aberration, are examined. The smallest possible value of the factor is found by allowing an unlimited number of centers constrained only to be within a ball rather than on icosahedral orbits. Computations using orbits formed by icosahedral vertices, face centers, and edge midpoints with a constraint radius limited to a small multiple of the Gaussian width show that a significant reduction of variance can be achieved from a small number of centers in the confined volume and that this reduction is nearly the maximum obtainable from an unlimited number of centers in the same volume.     

Examples of design curves for multirow arrays used with time-shift compensation

The effect of 1.75-D array element height on time-shift compensation is analyzed using a two-dimensional array system and a distributed aberration phantom. The analysis uses hydrophone measurements of transmit beams. The results indicate that, for imaging at 3 MHz through aberration representative of the abdominal wall, similar focus compensation performance can be expected from arrays with element pitches less than or equal to 3.0 mm.