PARAMETERS DETERMINATION METHOD OF PHASE-SPACE RECONSTRUCTION BASED ON DIFFERENTIAL ENTROPY RATIO AND RBF NEURAL NETWORK简

Phase space reconstruction is the first step of recognizing the chaotic time series. On the basis of differential entropy ratio method, the embedding dimension mopt and time delay τ are op- ritual for the state space reconstruction could be determined. But they are not the optimal parameters accepted for prediction. This study proposes an improved method based on the differential entropy ratio and Radial Basis Function （RBF） neural network to estimate the embedding dimension rn and the time delay τ, which have both optimal characteristics of the state space reconstruction and the prediction. Simulating experiments of Lorenz system and Doffing system show that the original phase space could be reconstructed from the time series effectively, and both the prediction accuracy and prediction length are improved greatly.     

Remaining useful life prediction of lithium-ion battery using an improved UPF method based on MCMC

Lithium-ion batteries are widely used as power sources in various portable electronics, hybrid electric vehicles, aeronautic and aerospace engineering, etc. To ensure an uninterruptible power supply, the remaining useful life (RUL) prediction of lithium-ion batteries has attracted extensive attention in recent years. This paper proposed an improved unscented particle filter (IUPF) method for lithium-ion battery RUL prediction based on Markov chain Monte Carlo (MCMC). The method uses the MCMC to solve the problem of sample impoverishment in UPF algorithm. Additionally, the IUPF method is proposed on the basis of UPF, so it can also suppress the particle degradation existing in the standard PF algorithm. In this work, the IUPF method is introduced firstly. Then, the capacity data of lithium-ion batteries are collected and the empirical capacity degradation model is established. The proposed method is used to estimate the RUL of lithium-ion battery. The RUL prediction results demonstrate the effectiveness and advantage.     

Adaptive and robust prediction for the remaining useful life of electrolytic capacitors

In integrated avionics systems, ensuring the high reliability and lengthening the life cycle of the avionics circuits become more and more important. This paper proposes an adaptive and robust prediction method to estimate the state of health and predict the remaining useful life (RUL) of electrolytic capacitors, which is one of the most significant components in avionics circuits. Based on an accelerated aging experiment performed by NASA, the degradation mechanism of electrolytic capacitors is analyzed. According to the capacitance loss data, a combination of the Verhulst model and the exponential model is adopted as the empirical model, and the unscented Kalman filter is applied to generate the proposal distribution of the particle filter to track the degradation path. Regarding the particle impoverishment, a particle swarm optimization algorithm is adopted to optimize the residual resampling step to improve the prediction accuracy. Also, adaptively adjusting the number of particles is introduced to make the algorithm more computationally efficient. Compared with the conventional particle filter algorithms, the experiment on the electrolytic capacitors degradation data indicates that the proposed novel method is able to provide a higher accuracy for the remaining useful life evaluation.     

A prognostic approach for non-punch through and field stop IGBTs

Development of prognostic approaches for insulated gate bipolar transistors (IGBTs) is of interest in order to improve availability, reduce downtime, and prevent failures of power electronics. In this study, a prognostic approach was developed to identify anomalous behavior in non-punch through (NPT) and field stop (FS) IGBTs and predict their remaining useful life. NPT and FS IGBTs were subjected to electrical–thermal stresses until their failure. X-ray analysis performed before and after the stress tests revealed degradation in the die attach. The gate–emitter voltage (V_GE), collector–emitter voltage (V_CE), collector–emitter current (I_CE), and case temperature were monitored in situ during the experiment. The on-state collector–emitter voltage (V_CE(ON)) increased and the on-state collector–emitter current (I_CE(ON)) decreased during the test. A Mahalanobis distance (MD) approach was implemented using the V_CE(ON) and I_CE(ON) parameters for anomaly detection. Upon anomaly detection, the particle filter algorithm was triggered to predict the remaining useful life of the IGBT. The system model for the particle filter was obtained by a least squares regression of the V_CE(ON) at the mean test temperature. The failure threshold was defined as a 20% increase in V_CE(ON). The particle filter approach, developed using the system model based on the V_CE(ON), was demonstrated to provide mean time to failure estimates of IGBT remaining useful life with an error of approximately 20% at the time of anomaly detection.     

On the practical realization of higher-order filters with fractional stepping

We propose the use of a compact integer-order transfer function approximation of the fractional-order Laplacian operator s^α to realize fractional-step filters. Lowpass and bandpass filters of orders (n+α) and 2(n+α), where n is an integer and 0<α<1, can, respectively, be designed. A 5th-order lowpass filter with fractional steps from 0.1 to 0.9 (i.e. 5.1→5.9) is given as an example with its characteristics compared to 5th- and 6th-order Butterworth filters. Spice simulations and experimental results are shown.     

Effects of high-field stressing on the channel frequency-response of MOSFETs

The frequency response of the MOSFET inverted channel is analyzed by a transmission-line model. In this model, the interface traps are included and the minority carriers are assumed to follow the surface-potential variation. The channel frequency-response is characterized by two time constants (τ_l and τ_GC). The conductance G_l and capacitance C₁ calculated from the minority-carrier current in the channel is used to determine τ_I and τ_GC from a frequency scan. Theoretical C₁(V) and G₁(V) curves are calculated and are in good agreement with experiments. The effect of high electrical field stressing is shown to increase both τ_I and τ_GC and thereby enlarge the frequency dispersion of the MOSFET admittances in inversion. The degradation in the channel frequency-response is more severe at lower inversion biases, where the degradation of mobility and the increase of interface-trap concentration are both more significant. The maximum of the G₁(V) curve is very sensitive to the mobility and interface-trap concentration and can be used to monitor the degradation of the MOSFET. The degradation of the channel response due to high-field stressing is shown to depend on the gate-oxide thickness.     

Novel Direction Findings for Cyclostationary Signals in Impulsive Noise Environments

We consider the problem of direction-of-arrival (DOA) estimation for cyclostationary signals in impulsive noise modeled as a complex symmetric α-stable (SαS) process. Since the DOA estimation based on second-order cyclic statistics degrades seriously in an α-stable distribution noise environment, we define a novel pth-order cyclic correlation by fusing the fractional lower order statistics and second-order cyclic correlation. After briefly introducing the statistical characteristics of pth-order cyclic correlation and building the extended data model, we first propose a novel extended pth-order cyclic MUSIC algorithm (EX-POC-MUSIC) by exploiting both pth-order cyclic correlation and pth-order cyclic conjugate correlation. The algorithm allows us to select desired signals and to ignore interference in the communication system. Second, in order to increase the resolution capabilities and the noise robustness significantly, an improved EX-POC-MUSIC algorithm called the extended pth-order cyclic Root-MUSIC (EX-POC-RMUSIC) algorithm is also presented. This algorithm has all the merits of the EX-POC-MUSIC algorithm, and it is also a fast DOA estimation algorithm because it avoids spatial spectrum searching. Under some conditions, both proposed algorithms are able to handle more sources than the number of sensors. Simulation results strongly verify the effectiveness of the two algorithms.     

群时延精确设计的全差分四阶Bessel滤波器

采用MOS管有源电阻,提出了一种全差分R-MOSFET-C四阶Bessel有源低通滤波器,.通过调节工作于亚阈值区的CMOS管的沟道导纳补偿电阻值的大小,能抵消集成电路制造工艺中电阻值的一致偏差,实现Bessel有源滤波器群时延的精确设计.根据无源滤波器的状态方程完成有源滤波器的综合,应用3.3V,0.5μm CMOS工艺完成了群时延大小为0.75μs的四阶Bessel低通滤波器的管极计算机仿真,仿真结果表明所提电路正确有效,适于全集成.     

Swarm intelligence driven design space exploration of optimal k-cycle transient fault secured datapath during high level synthesis based on user power–delay budget

Fault security indicates ability to provide error detection or fetch correct output. Fault security assures possibility of using either hardware redundancy or time redundancy to optimize the overheads associated with fault security. However, generation (design space exploration (DSE)) of an optimal fault secured datapath structure based on user power–delay budget during high level synthesis (HLS) in the context k-cycle transient fault is considered an intractable problem. This is due to the fact that for every type of candidate design solution produced during exploration, a feasible k-cycle fault secured datapath may not exist which satisfies the conflicting user constraints/budget. Secondly, insertion of inapt cut (resulting in an additional checkpoint) to optimize delay overhead associated with fault security in most cases may not result in optimal solutions in the context of user constraints/budgets. The solutions to the above problems have not been addressed in the literature so far. The paper therefore presents the following novelties: (a) an algorithm for fault secured DSE process (b) handling k-cycle transient faults during DSE (c) schemes for selecting appropriate edges for inserting cuts that selects available locations in the scheduled Control Data Flow Graph (CDFG) which minimizes delay overhead associated with fault security (d) swarm intelligence (particle swarm optimization) driven DSE process that adaptively/intelligently computes the candidate design solutions for generating an optimal fault secured datapath.Results of the proposed approach when tested on standard benchmarks yielded optimal results in most cases as evident from the data obtained for generational distance (GD), spacing (S), spreading (Δ) and weighted metric (W_m). Further, results of comparison with a recent approaches indicated significant reduction of final cost (better quality) for the proposed approach.     

An 8.25-MHz 7th-Order Bessel Filter Built with Single-Amplifier Biquadratic MOSFET–C Filters

This paper is a practical guide to building higher-order filters with single-amplifier biquadratic MOSFET–C sections. Theory, design guidelines, and measurement electronics are discussed by example of a 7th-order current-mode filter built to the specifications of a 1× DVD read channel filter. The 7th-order filter was fabricated with the double-poly 0.6-micron CMOS process by AMS. It is continuously tunable from 4.5 MHz up to 10 MHz, covers a chip area of only 0.24 mm², and consumes 49 mW from a 3.3-V supply. The SNR at -40 dB of harmonic distortion is between 48 dB and 50 dB over the whole tuning range. The comparatively low power consumption and chip area could be achieved by using single-amplifier biquadratic building blocks implemented as MOSFET–C filters and generating the control voltage of the MOSFET resistors with an on-chip charge pump. The technique is, with a small loss of SNR, also applicable on fabrication processes where only gate-oxide capacitors are available.     

SiGe: An attractive material for post-CMOS processing of MEMS

This work gives an overview of the different developments for silicon germanium (Si_1−xGe_x) from a MEMS post-processing perspective. First, the maximum processing temperature that does not introduce any damage or degradation into the standard characteristics of the CMOS driving electronics is specified. Then, the optimal type of silicon and germanium gas sources and deposition technique that results in an economical process are identified. Next, the selection criteria for a low thermal budget doping method and doping species are discussed. Finally, the advantage and disadvantage for the different approaches implemented for enhancing the physical properties of poly Si_1−xGe_x at a CMOS backend compatible temperature are highlighted. It is shown that the optimal method depends on the application requirements and the CMOS technology used for realizing the driving electronics.     

Current Differencing Cascaded Transconductance Amplifier (CDCTA) and Its Applications on Current-Mode nth-Order Filters

In this paper, a new active device, current differencing cascaded transconductance amplifier (CDCTA), has been presented. The proposed CDCTA simplifies the design of the current-mode filter circuit considerably, especially the design of high-order filter. Moreover, a current-mode nth-order filter based on the CDCTA is proposed in the paper. The proposed circuit, which adopts only an active component and n grounded capacitors, contains minimal active component and passive one. It enjoys the simple configuration and is suitable for integrated circuit (IC) fabrication. PSpice simulations for current-mode third-order filter based on this structure have also been conducted, and the results are in good agreement with the theoretical analysis. The influences of the CDCTA non-idealities are also discussed.     

Experimental investigation of turn-on spread in a thyristor

The dependence of the spreading velocity of the turned-on state in a thyristor on the load current density is measured in the presence of a turn-off gate current as well as without it. For the same thyristor the critical charge density n_c and the dependence of turn-on time constant τ₁ of turned-off parts of the thyristor on the load current density j_a flowing through the turned-on part are also measured. The data obtained make it possible to compare in detail the experimental results with the recently proposed phenomenological theory of the spreading of the turned-on state. Our investigations show that the theory describes well all the experimental results. The τ₁(j_a) dependence is of great importance in the spreading of the turned-on state. The inhomogeneities of the critical charge density n_c at different points of the structure have a considerable influence on the condition of the spread.The data obtained improve the understanding of the turn-on process and allow to calculate the spreading velocity of the turned-on state in thyristors.     

基于粒子滤波与样本加权的压缩跟踪算法

该文针对压缩跟踪算法无法适应目标尺度的变化以及没有考虑样本权重的问题,提出一种基于粒子滤波与样本加权的压缩跟踪算法。首先,对压缩特征进行改进,提取归一化矩形特征用于构建目标表观模型。然后,引入样本加权的思想,根据正样本与目标之间距离的不同赋予正样本不同的权重,提高分类器的分类精度。最后,在粒子滤波的框架下融合尺度不变压缩特征进行动态状态估计,在粒子预测阶段利用2阶自回归模型对粒子状态进行估计与预测,借助观测模型对粒子状态进行更新,并且对粒子进行重采样以防止粒子退化。实验结果表明,相比于原始压缩跟踪算法,改进算法能够更好地跟踪目标尺度的变化,提高跟踪的稳定性和准确性。     

Investigation of Trap States in Mid-Wavelength Infrared Type II Superlattices Using Time-Resolved Photoluminescence

Time-resolved photoluminescence (TRPL) spectroscopy is used to study the minority-carrier lifetime in mid-wavelength infrared, n-type, InAs/Ga_1?x In _x Sb type II superlattices (T2SLs) and investigate the recombination mechanisms and trap states that currently limit their performance. Observation of multiple exponential decays in the intensity-dependent TRPL data indicates trap saturation due to the filling then emptying of trap states and different Shockley–Read–Hall (SRH) lifetimes for minority and majority carriers, with τ _maj (τ _n0) ? τ _min (τ _p0). Simulation of the photoluminescence transient captures the qualitative behavior of the TRPL data as a function of temperature and excess carrier density. A trap state native to Ga_1?x In _x Sb is identified from the low-injection temperature-dependent TRPL data and found to be located below the intrinsic Fermi level of the superlattice, approximately 60 ± 15 meV above the valence-band maximum. Low-temperature TRPL data show a variation of the minority-carrier SRH lifetime, τ _p0, over a set of InAs/Ga_1?x In _x Sb T2SLs, where τ _p0 increases as x is varied from 0.04 to 0.065 and the relative layer thickness of Ga_1?x In _x Sb is increased by 31%.     

The theory of majority-carrier motion in the Haynes-Shockley experiment

The time-dependent coupled linearized diffusion equations for majority and minority carriers in a semiconductor are solved exactly for the situation found in the Haynes-Shockley experiment where a δ-function pulse of electron-hole pairs is injected at an initial time and place. In the recombination regime, where the minority-carrier lifetime τ_min is much greater than the dielectric relaxation time τ_D, the calculations show the expected quasi-neutrality, but in the relaxation regime, where τ_min is less than τ_D, a quite different state of affairs prevails. The majority carriers now move off in the opposite direction to the minority carriers which are accompanied by a region depleted of majority carriers. When τ_min is slightly greater than τ_D, the majority carriers may show a spatial distribution with a double hump.     

基于时间序列自适应建模的粒子滤波动态目标跟踪

在目标跟踪中为达到目标的运行模型与实际轨迹相符,本文提出基于时间序列自适应建模的粒子滤波算法（TS_PF）。采用时间序列方法动态构建预测模型,并将粒子滤波算法中一系列加权粒子以该模型进行状态转移,运用粒子滤波重采样技术,使预测误差进一步减小,预测精度逼近最优估计。仿真实验表明在粒子滤波算法中采用时间序列自适应建模,能够...     

Mobile robot SLAM method based on multi-agent particle swarm optimized particle filter

To overcome particle impoverishment, a simultaneous localization and mapping (SLAM) method based on multi-agent particle swarm optimized particle filter (MAPSOPF) was presented by introducing the idea of multi-agent to the particle swarm optimized particle filter (PSOPF) which is an algorithm for SLAM. In MAPSOPF, agents can communicate and compete with each other and learn from each other. The MAPSOPF algorithm can update the prediction of particle, adjust the proposal distribution of particles, improve localization precision and fault tolerance, and propel the particles to concentrate on the robot's true pose. Compared with standard particle filter (PF), the proposed method can achieve better SLAM precision by fewer particles. Simulations verify its effectiveness and feasibility.     

A new multiple extended target tracking algorithm using PHD filter

A new multiple extended target tracking algorithm using the probability hypothesis density (PHD) filter is proposed in our study, to solve problems on tracking performance degradation of the extended target PHD (ET-PHD) filter under the nonlinear conditions and its intolerable computational requirement. It is noted that with the current Gaussian mixture implement of ET-PHD filter satisfying tracking performance could only be obtained under linear and Gaussian conditions. To extend the application of ET-PHD filter for nonlinear models, our study has derived a particle implement of ET-PHD (ET-P-PHD) filter. Our study finds that the main factors influencing the computational complexity of the ET-P-PHD filter are the partition number of measurement set and the calculation of non-negative coefficients of cells in partitions. With the pretreatment of measurements and application of a new K-means clustering based measurement set partition method, we have successfully decreased the partition number. In addition, a gating method for target state space, which is based on likelihood relationship between target state and measurement, is proposed to simplify the calculation of non-negative coefficients. Simulation results show that the algorithms proposed by our study could satisfyingly deal with multiple extended target tracking issues under nonlinear conditions, and lead to significantly lower computational complexity with tiny effect on tracking performance.     

Multi-Scale Prediction of RUL and SOH for Lithium-Ion Batteries Based on WNN-UPF Combined Model

The prediction of Remaining useful life (RUL) and the estimation of State of health (SOH) are extremely important issues for operating performance of Lithium-ion (Li-ion) batteries in the Battery management system (BMS). A multi-scale prediction approach of RUL and SOH is presented, which combines Wavelet neural network (WNN) with Unscented particle filter (UPF) model. The capacity degradation data of Li-ion batteries are decomposed into the low-frequency degradation trend and high-frequency fluctuation components by Discrete wavelet transform (DWT). Based on the WNN-UPF model, the long-term RUL of Li-ion batteries is predicted with the low-frequency degradation trend data. The high-frequency fluctuation data and RUL prediction results are integrated effectively to estimate the short-term SOH of Li-ion batteries. The experimental results show that the proposed method achieves high accuracy and strong robustness, even if the prediction starting point is set to the early stage of Li-ion batteries' lifespan.