Multi-mode data augmentation and fault diagnosis of rotating machinery using modified ACGAN designed with new framework

As one of the representative unsupervised data augmentation methods, generative adversarial networks (GANs) have the potential to solve the problem of insufficient samples in fault diagnosis of rotating machinery. However, the existing unsupervised GANs are usually incapable of simultaneously generating multi-mode fault samples and have some shortcomings such as mode collapse and gradient vanishing. To overcome these deficiencies, a supervised model called modified auxiliary classifier GAN (MACGAN) designed with new framework is proposed in this paper. Firstly, a new ACGAN framework is developed by adding an independent classifier to improve the compatibility between the classification and discrimination. Secondly, the Wasserstein distance is introduced in the new loss functions to overcome mode collapse and gradient vanishing. Finally, to achieve stable training, a spectral normalization is used to replace the weight clipping to constrain the weight parameters of discriminator. The proposed method is applied to fault diagnosis of bearing and gear. Compared with the existing GANs, the proposed method can more efficiently generate multi-mode fault samples with higher qualities, which can be used to assist the training of deep learning-based fault diagnosis models with high accuracy and good stability.     

Real-Time Assessment and Diagnosis of Process Operating Performance

Over time, the performance of processes may deviate from the initial design due to process variations and uncertainties, making it necessary to develop systematic methods for online optimality assessment based on routine operating process data. Some processes have multiple operating modes caused by the set point change of the critical process variables to achieve different product specifications. On the other hand, the operating region in each operating mode can alter, due to uncertainties. In this paper, we will establish an optimality assessment framework for processes that typically have multi-mode, multi-region operations, as well as transitions between different modes. The kernel density approach for mode detection is adopted and improved for operating mode detection. For online mode detection, the model-based clustering discriminant analysis (MclustDA) approach is incorporated with some a priori knowledge of the system. In addition, multi-modal behavior of steady-state modes is tackled utilizing the mixture probabilistic principal component regression (MPPCR) method, and dynamic principal component regression (DPCR) is used to investigate transitions between different modes. Moreover, a probabilistic causality detection method based on the sequential forward floating search (SFFS) method is introduced for diagnosing poor or non-optimum behavior. Finally, the proposed method is tested on the Tennessee Eastman (TE) benchmark simulation process in order to evaluate its performance.     

On the development of high-throughput and area-efficient multi-mode cryptographic hash designs in FPGAs

In this paper, area-efficient and high-throughput multi-mode architectures for the SHA-1 and SHA-2 hash families are proposed and implemented in several FPGA technologies. Additionally a systematic flow for designing multi-mode architectures (implementing more than one function) of these families is introduced. Compared to the corresponding architectures that are produced by a commercial synthesis tool, the proposed ones are better in terms of both area (at least 40%) and throughput/area (from 32% up to 175%). Finally, the proposed architectures outperform similar existing ones in terms of throughput and throughput/area, from 4.2× up to 279.4× and from 1.2× up to 5.5×, respectively.     

一种0.13 μm CMOS多模信道选择滤波器的设计

设计了一款应用于多模多频无线接收机中的新型有源电阻电容信道选择滤波器,截止频率可在0.3～10MHz之间切换,满足UHF RFID、TD-SCDMA、WLAN a/b/g等不同标准的要求。运算放大器设计采用无电容前馈补偿技术,增益带宽积提升至4.8GHz。滤波器采用5阶Leapfrog滤波器级联2阶Tow-Thomas滤波器结构,使截止频率不易受器件变化的影响,同时兼顾稳定性和可调性。电路采用IBM 0.13μm CMOS工艺流片。测试结果表明,在2.5V电源电压下选择10MHz带宽时,滤波器消耗13.56mA电流,在两倍截止频率处实现64dB的衰减,带内噪声系数为28dB,带内纹波小于0.2dB,带内输入3阶交调为11.5dBm。     

Multi-mode control strategy for fuel cell electric vehicles regarding fuel economy and durability

A proton electrolyte membrane (PEM) fuel cell system and a Li-ion battery (LIB) are two power sources in a fuel cell electric vehicle (FCEV). The fuel cell system is composed of a fuel cell stack and subsystems for air/hydrogen supply and cooling water. The operation procedure of the fuel cell system can be generally separated into several processes, e.g. starting up, normal/abnormal working and shutting down. In this paper, a multi-mode real-time control strategy for a FCEV is proposed. The strategy is established based on three typical processes (starting up, normal working, shutting down) of the fuel cell system, taking the fuel economy and system durability into consideration. The strategy is applied into a platform vehicle for the 12th 5-year project of “the next generation technologies of fuel cell city buses”. Experiments of the “China city bus typical cycle” on a test bench for the bus were carried out. Results show that, the fuel economy is 7.6 kg (100 km)⁻¹ in the battery charge-sustaining status. In a practical situation, a total driving mileage of more than 270 km can be achieved. Cycle testing also showed that, the degradation rate of the fuel cell was reduced to half of the original level. No performance degradation of the LIB system was observed in the cycling test.     

H.264/AVC视频编码标准的技术特点及应用分析

H.264／AVC是ITU-T视频编码专家组和ISO／IEC运动图像专家组(MPEG)共同开发出来的最新视频编码标准,它具备许多新的技术特点,如:多模式运动预测、柔性宏块排序、整数变换、一致性变字长编码、内容自适应二进制算术编码、分层编码、错误约束机制、错误掩盖技术及高效的比特流切换技术等等。本文在阐述该标准系统层结构的基础上,分析其主要技术特点及H.264／AVC VBR码流特性,阐述该标准在IP网络及无线网络中的应用情况。     

Design and analysis of a super compact wide-band bandpass filter based on metamaterial resonators

In this paper, a novel compact wide-band bandpass filter (BPF) with a wide frequency range is presented. This filter consisting of a multi-mode resonator (MMR) and four metamaterial unit-cells benefits from a very compact size. Unit-cells based on a complementary spiral resonator (CSR) including a metallic via, improve both upper and lower stopband rejection and compensate the insertion loss (I.L) within the passband altogether. This wide-band filter presents a 3-dB bandwidth of 7.7 GHz, ranging from 3 GHz to 10.7 GHz and the Insertion loss is less than 0.7 dB over the passband. The measured results are in good agreement with both the full-wave electromagnetic simulation and the proposed circuit model results. The dimension of the fabricated filter is 0.128 λ × 0.1 λ (i.e., 5.6 × 4.4 mm²). This filter is considerably compact compared to the other wide-band bandpass filters with the same substrate.     

Case specific prediction intervals for tri-PLS1: The full local linearisation

A new method to estimate case specific prediction uncertainty for univariate trilinear partial least squares (tri-PLS1) regression is introduced. This method is, from a theoretical point of view, the most exact finite sample approximation to true prediction uncertainty that has been reported up till now. Using the new method, different error sources can be propagated, which is an advantage that cannot be offered by data driven approaches such as the bootstrap. In a concise example, it is illustrated how the method can be applied. In the Appendix, efficient algorithms are presented to compute the estimates required.     

Adaptive multi-mode switching strategy for the spherical underwater robot with hybrid thrusters

The conventional autonomous cruise and tracking system cannot transition and change its motion mode according to the underwater environment during operation, so it is of great significance to study the multi-mode switching of cruise control for Autonomous Underwater Vehicles (AUVs). In this paper, a Multi-Mode Adaptive Switching (MMAS) strategy for the Spherical Underwater Robot with Hybrid Thruster (HPSUR) was proposed, which provided the possibility for the robot to choose optimal control mode according to the unpredictable operating environment. Then, the dynamic and force of the hybrid thruster are analyzed to improve the accuracy of multi-mode switching, and the MMAS strategy is developed linking the attitude adjustment and switching problems. Furthermore, a series of multi-mode switching experiments were conducted using water-jet mode, propeller mode and hybrid mode. Finally, the experimental result was discussed, which verified the effectiveness and accuracy of the proposed MMAS strategy. The proposed control strategy has a certain reference value for the multi-mode switching of propulsion devices.     

基于FPGA的可重构系统的应用

基于FPGA的可重构系统的出现,引发了计算和数字逻辑样式的变革。作为逻辑仿真系统,它的仿真速度比软件仿真要快数个量级;作为用户计算机,它在多种类型的应用实现中获得高效率的系统性能;作为多模式系统,它节省了硬件开支,并提供了真正意义上的通用硬件。