Neural‐hybrid control of systems with sandwiched dead‐zones

The control of systems that have sandwiched nonsmooth nonlinearities, such as a dead‐zone sandwiched between two dynamic blocks, is addressed. An adaptive inverse control scheme using a hybrid controller structure and a neural network based inverse compensator, is proposed for such systems with unknown sandwiched dead‐zone. This neural‐hybrid controller consists of an inner loop discrete‐time feedback structure incorporated with an adaptive inverse using a neural network for the unknown dead‐zone, and an outer‐loop continuous‐time feedback control law for achieving desired output tracking. The dead‐zone compensator consists of two neural networks, one used as an estimator of the sandwiched dead‐zone function and the other for the compensation itself. The compensator neural network has neurons that can approximate jump functions such as a dead‐zone inverse. The weights of the two neural networks are tuned using a modified gradient algorithm. Simulation results are given to illustrate the performance of the proposed neural‐hybrid controller. Copyright © 2002 John Wiley & Sons, Ltd.     

Parallel realization of algebraic domain decomposition for the vector finite element analysis of 3D time‐harmonic EM field problems

Based on message passing interface (MPI) distributed‐memory network, we propose a parallel realization of algebraic domain decomposition method to solve the large sparse linear systems, which were derived from the vector finite element method (FEM) for three‐dimensional electromagnetic field problems. The proposed method segments the problem into several smaller sub‐problems, solves each sub‐problem in each node (i.e. computer) by the direct method, exchanges related data between nodes with MPI cluster network, and then reassembles the sub‐problem solutions together to get the global result. Multifrontal method is applied to solve intermediate equations associated with each sub‐problem and conjugate gradient methods are used to solve the reduced interface system. The simulation results demonstrate that the proposed parallel computing can save much more memory and CPU time than sequential computing. Furthermore, it can solve larger system in reasonable time and get excellent performance vs price ratio. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of Pre-annealing to Blocking Oxide on the Performance of Dual Trapping-layer Engineered Charge Trapping Memory

The effect of pre-annealing to blocking oxide on the performance of trapping layer engineered charge trapping flash memory was investigated in this work. Compared to the devices fabricated by conventional process, the devices with pre-annealing treatment exhibit larger memory window, faster program speed, and significantly improved data retention. The enhancement of memory performance and reliability can be possible from the improvement of blocking oxide quality and the change of band-gap and band offsets in memory gate stack. The findings provide a useful guide for CTM process optimization.     

Adaptive homo‐backstepping tracking control for strict‐feedback systems in presence of unknown dead‐zones

An adaptive homo‐backstepping control for nonlinear strict‐feedback systems subjected to unknown actuator dead‐zone and disturbance is investigated. A sliding‐mode‐based integral filter is constructed and used to approximate the desired feedback control in the backstepping‐like recursive design technique. Subsequently, the problem of “explosion of complexity” is solved by obviating the analytic derivatives deduction for virtual control in the conventional backstepping technology. The actuator dead‐zone dynamic is modeled as the combination of a line and a disturbance‐like term, which makes the controller design simpler. The interconnected control module and filter module in the resulting closed‐loop system satisfy the input‐to‐state practically stability‐modularity condition, provided that the small‐gain theorem is exploited to ensure the stability of closed‐loop system. The proposed approach cannot only mitigate the effect of dead‐zone but also solve the problem of explosion of complexity in the previous literature. Numerical simulations performed on a manipulator with a brushed DC motor are introduced to illustrate the effectiveness of underlying control scheme.     

Constructive approximation of non‐linear discrete‐time systems

It is known that large classes of approximately‐finite‐memory maps can be uniformly approximated arbitrarily well by the maps of certain non‐linear structures. As an application, it was proved that time‐delay networks can be used to uniformly approximate arbitrarily well the members of a large class of causal nonlinear dynamic discrete‐time input–output maps. However, the proof is non‐constructive and provides no information concerning the determination of a structure that corresponds to a prescribed bound on the approximation error. Here we give some general results concerning the problem of finding the structure. Our setting is as follows. There is a large family 𝒢 of causal time‐invariant approximately‐finite‐memory input‐output maps G from a set S of real d‐vector‐valued discrete‐time inputs (with d⩾1) to the set of ℝ‐valued discrete‐time outputs, with both the inputs and outputs defined on the non‐negative integers 𝒵₊. We show that for each ϵ>0, any Gϵ𝒢 can be uniformly approximated by a structure map H(G, ·) to within tolerance ϵ, and we give analytical results and an example to illustrate how such a H(G, ·) can be determined in principle. Copyright © 2000 John Wiley & Sons, Ltd.     

Robust output tracking of uncertain nonlinear systems with completely unknown dead‐zone input: A self‐tuning design approach

The main purpose of this paper is to propose a direct and simple approach, called a self‐tuning design approach, to dealing with any nonsymmetric dead‐zone input nonlinearity where its information is completely unknown. In order to describe the approach, the output tracking problem is considered for a class of uncertain nonlinear systems with any nonsymmetric dead‐zone input. First, a dead‐zone input is represented as a time‐varying input‐dependent function such that the considered dynamical system with dead‐zone input can be transfered into an uncertain nonlinear dynamical system subject to a linear input with time‐varying input coefficient. Then, by making use of the self‐tuning design approach, a class of adaptive robust output tracking control schemes with a rather simple structure is synthesized. Thus, the proposed direct and simple self‐tuning design approach can be easily understood by the engineering designers, and the resulting simple adaptive robust control schemes can be well implemented in most practical engineering control problems. By combining the proposed self‐tuning design approach with other control methods, one may expect to obtain a number of interesting results for a rather large class of uncertain nonlinear dynamical systems with dead‐zone in the actuators. Finally,the simulations of some numerical examples are provided to demonstrate the validity of the theoretical results. Copyright © 2016 John Wiley & Sons, Ltd.     

Second order mem‐circuits

This paper presents a comprehensive taxonomy of so‐called second‐order memory devices, which include charge‐controlled memcapacitors and flux‐controlled meminductors, among other novel circuit elements. These devices, which are classified according to their differential and state orders, are necessary to get a complete extension of the family of classical nonlinear circuit elements (resistors, capacitors, and inductors) for all possible controlling variables. Using a fully nonlinear formalism, we obtain nondegeneracy conditions for a broad class of second‐order mem‐circuits. This class of circuits is expected to yield a rich dynamic behavior; in this regard, we explore certain bifurcation phenomena exhibited by a family of circuits including a charge‐controlled memcapacitor and a flux‐controlled meminductor, providing some directions for future research. Copyright © 2014 John Wiley & Sons, Ltd.     

Large‐scale magnetic field analysis by the hybrid finite element‐boundary element method combined with the fast multipole method

This paper describes a large‐scale magnetic field analysis by means of the hybrid finite element‐boundary element (FE‐BE) method. The hybrid FE‐BE method is well‐suited for solving open electromagnetic field problems that comprise movement, nonlinear media, and eddy current. In general, however, large memory and computational costs are required due to the dense blocks in the system matrix generated by the BE part of the hybrid formulation. In order to overcome the above difficulties, we introduce the fast multipole method (FMM) to the hybrid FE‐BE formulation developed by ourselves. Furthermore, we propose a novel preconditioning technique suitable for the hybrid FE‐BE method with the FMM. Some numerical results that demonstrate the effectiveness of the proposed approach are also presented. ©2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 73–80, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20508     

A dual‐primal finite‐element tearing and interconnecting method combined with tree‐cotree splitting for modeling electromechanical devices

The dual‐primal finite‐element tearing and interconnecting (FETI‐DP) method is combined with the tree‐cotree splitting (TCS) method to expand the capability and improve the efficiency of the finite‐element analysis of electromechanical devices. With the FETI‐DP method, an original large‐scale problem is decomposed into smaller subdomain problems and parallel computing schemes are then employed to reduce the computation time significantly. The TCS method is adopted to deal with the low‐frequency breakdown problem, which often accompanies the finite‐element analysis of electromechanical problems. On the basis of the computed magnetic field values, the force is computed with the use of the Maxwell stress tensor method. The proposed technique is applied to solve both high‐contrast magnetostatic problems and eddy‐current problems. Results are compared with both measurement data and brute‐force finite‐element calculations without domain decomposition. Comprehensive tests are conducted to investigate the parallel efficiency and numerical scalability. The results show that the proposed method can achieve a good parallel efficiency and an excellent numerical scalability with respect to the number of subdomains and the size of the problem. Copyright © 2012 John Wiley & Sons, Ltd.     

A study of series‐parallel changeover circuit of a capacitor bank for an energy storage system utilizing electric double‐layer capacitors

Electric double‐layer capacitors showing a remarkably high energy density (compared with conventional electrolytic capacitors) are now under development. Capacitors of this type have significant advantages, namely, high durability against repeated charge and discharge and no need for maintenance. Therefore, we have studied feasible basic circuit configurations and control methods required to apply electric double‐layer capacitors as an energy storage element in output‐power leveling systems for solar cells or windmill power generators, and in uninterruptible power supply systems. This paper discussed operating methods for a capacitor bank to improve the efficiency. High efficiency has been demonstrated by the simulations and the experiments. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(3): 33–42, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10155     

Inverse‐free second moment method for electrical systems with uncertain parameters

Engineering systems are usually designed deterministically, but if there are uncertainties in parameters, an appropriate approach is to use probabilistic methods. For reliability estimation it is necessary to have at least the first two moments including means and covariances of the output variables. Most of the existing methods applied to problems involving linear systems need inverses of matrices. There are two problems with these approaches. First, for large sparse linear systems (for example, a tri‐diagonal system) the inverse is fully dense. Second, the mean of the random matrix has to be non‐singular. In this paper, we present a new method to automatically formulate the moment equations that aims to overcome the drawbacks of these methods and apply it on electrical networks. This method does not require an inverse and able to solve problems when the mean matrix of a system is singular. In addition, it takes advantage of both sparsity (zero elements) and deterministic coefficients. This method can be used to solve both uncorrelated and correlated cases. To demonstrate the feasibility of this method, a quantitative comparison with another existing method requiring the inverse and with Monte Carlo results is done. Copyright © 2005 John Wiley & Sons, Ltd.     

Visual‐based and object‐conscious image retrieval by block reallocation into object region

‘Visual‐based’ image retrieval based on the visual similarities over the entire image is one of the powerful and useful ways when targeting large volume content with inadequate annotation. Generally, conventional methods divide a query image and target images in the database into grid‐shaped blocks and calculate the similarity based on image features by comparing each corresponding block straightforwardly. However, the method sometimes fails in terms of object‐conscious retrieval when their backgrounds are almost the same but the only the object is different or the object's size and/or position is different. To solve the problem, we propose a new method featuring the reallocation of some blocks to the object region (OB‐blocks) and a new similarity score by placing a weight on the OB‐blocks, which are derived from the visual saliency map. Our proposed method could realize ‘visual‐based and object‐conscious’ image retrieval. We verify the effectiveness of this method through comparison experiments. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Energy‐efficient human probes for high‐resolution sensing in urban environments

Portable sensory devices carried by humans—which are referred to as Human Probes—facilitate easy‐to‐use sensing and monitoring of urban areas. However, when each Human Probe individually senses and transmits information, the sensing activity is inefficient in terms of energy consumption. In this paper, we propose Aquiba protocol in which the sensing activities carried out by the Human Probes are adjusted autonomously under different conditions. Aquiba involves cooperative sensing that helps in efficiently maintaining the desired sensing resolution, while minimizing overall energy consumption. To validate Aquiba protocol, we have conducted comprehensive simulations by including small‐scale and large‐scale scenarios along with applying three movement patterns of human. The simulation results demonstrate that Aquiba protocol is capable of providing high sensing resolution and reducing energy consumption substantially. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Circuits simulation of switch devices furnished with gain cell combined to FeRAM

Abstract

This paper has described a new concept on programmable switch device furnished with gain cell combined to FeRAM. Compared with memories but ferroelectric memories under many aspects, they have even been favorably labeled the ideal memory because of their non-volatility, ease of programming and operation by low voltage. As the programming switch, which is very attractive for logic application, SRAM, anti-fuse, flash type devices are well known. They have been required that satisfy non-volatility and low-voltage programming simultaneously. Some structures with ferroelectric material have been proposed and studied as solution of these problems. However, it seemed hard that these type devices are realized now from a viewpoint of fabrication process and low voltage operation. Therefore, we propose a new switch device furnished with gain cell combined to FeRAM. We have studied and simulated this switch device by SPICE. This basic circuit is composed of two blocks. One is switching block that includes gain cell, and the other is memory block that is FeRAM. Circuits, which we designed, amplify bit line's voltage up to Vdd or ground at sense amplification according to FeRAM data. The bit line voltage determines the logic state for gate electrode of switch transistor. The way to read is destructive read out. However, we can transfer information of bit line voltage during plate line is low-level voltage. The way to write FeRAM is similar to conventional way. It is revealed that the basic circuit with FeRAM connected gain cell could work correctly in simulation. In addition, this kind of device is hopeful of many logic applications.     

A unified proposal for characteristic testing methods and figure of merit of 8‐kV/3.5‐kVA class light‐triggered thyristors

Power devices with high capability have been developed. 8‐kV/3.5‐kA‐class light‐triggered thyristors have the highest capability among power devices. These devices are used in the Kii Channel HVDC transmission system in Japan. In this paper, we report the extracted problems of conventional testing methods of 8‐kV/3.5‐kA‐class light‐triggered thyristors among manufacturers, and the proposed unified testing methods on the basis of element characteristics and operating conditions in the Kii Channel HVDC system. Furthermore, we propose a figure of merit for power devices for the practical use, and try to extract elements used at the Kii Channel HVDC system with small margins and low withstand capabilities. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(3): 61–70, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10024     

A control method for small‐scale DC power systems including distributed generators

This paper describes a DC micro‐grid system interconnecting distributed power generators. The system consists of five generation and control units: a solar‐cell generation unit, a wind‐turbine generation unit, a battery energy‐storage unit, a flywheel power‐leveling unit, and an AC grid‐interconnecting power control unit. The control method is proposed for suppressing the circulating current by detecting only the DC grid voltage. This method brings high reliability, high flexibility, and maintenance‐free operation to the system. The method pays attention to DC output voltage performance of each unit. Each of the power control units and the energy‐storage unit is controlled to act as a voltage source with imaginary impedance. On the other hand, each of the two generation units is controlled to act as a current source. The power‐leveling unit is controlled to act as a current source having the function of frequency selectivity like a high‐pass filter. A 10‐kW prototype system verifies experimentally the validity and effectiveness of the proposed control method for the DC‐grid system. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 86–93, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20603     

CMT‐CQA: Cross‐layer QoS‐aware adaptive concurrent multipath data transfer in heterogeneous networks

Stream control transport protocol (SCTP)‐based concurrent multipath transfer (CMT) can help multi‐homed devices to increase their throughput by making use of parallel transmissions over multiple paths and bandwidth aggregation. However, if CMT cannot identify wireless error, it cannot really achieve the desired performance. Furthermore, if CMT only utilizes all available paths for data delivery, it will undoubtedly degrade application‐level performance since the asymmetric paths may involve large quality differences. This paper proposes a novel cross‐layer quality‐of‐service (QoS)‐aware adaptive CMT (CMT‐CQA) with the following aims: (i) to provide an adaptive ‘CMT‐to‐partial CMT’ adjustment strategy for efficient bandwidth aggregation by jointly considering transport layer QoS, MAC layer QoS, and path history information; (ii) to address an enhanced congestion window (cwnd) fast recovery mechanism to reduce bursty transmission in multi‐homed wireless network environments where fail‐over occurs frequently; and (iii) to introduce a proper multimedia transmission behavior to improve users' quality of experience (QoE) for multimedia streaming service. Simulation results show that CMT‐CQA outperforms the existing CMT solutions in terms of performance and QoS. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Stability analysis and adaptive control for nonlinear discrete‐time systems with time delays and dead zone via state‐feedback technique

This research addresses the stability analysis and adaptive state‐feedback control for a class of nonlinear discrete‐time systems with multiple interval time‐varying delays and symmetry dead zone. The multiple interval time‐varying delays and symmetry dead zone are considered in the nonlinear discrete‐time system. The multiple interval time‐varying delays are bounded by the nonlinear function with unknown coefficients, and the symmetry dead zone is considered without the knowledge of the dead zone parameters. The adaptive state‐feedback controller is designed for the nonlinear discrete‐time systems with multiple interval time‐varying delays and dead zone. The discrete Lyapunov‐Krasovskii functional is introduced, such that the solutions of the closed‐loop error system converge to an adjustable bounded region and the state errors can be rendered arbitrarily small by adjusting the adaptive parameters. The designed adaptive state‐feedback controller does not require the knowledge of maximum and minimum values for the characteristic slopes of the dead zone. Finally, three simulation examples are given to show the effectiveness of the proposed methods.     

Design of a contention‐free parallel double‐flow MAP decoder

Parallel processing and double‐flow methods, which are used to increase the speed of turbo‐code decoding, cause memory contentions. Although memory contentions due to parallel processing can be resolved by adopting the quadratic polynomial permutation (QPP) interleaver, the double‐flow method still causes memory contentions because of its read/write sequences from both ends of the input packets. Thus, we propose a modified architecture to resolve memory contentions for the double‐flow method to fit the QPP interleaver. In our experiment, the proposed method has a shorter decoding time and smaller hardware size compared the conventional method. A bit‐accurate simulation was performed, and hardware implementation with field‐programmable gate arrays (FPGAs) led to a high throughput of 80 Mbps. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

嵌入式Flash存储器控制器的设计方法

本文介绍了嵌入式存储器技术及一种存储器控制器的设计方法,通过研究Flash地址线和不同块的结构特征,结合CPU存储空间的分配,选择适当的RAM/ROM总线到Flash地址线的映射关系,然后根据Flash的时序要求为敏感时间参数定时,同时考虑系统时钟的变化范围,划分频率区间以提高精度,本设计以特殊功能寄存器总线作为与CPU的接口,实现了通过软件编程从而对Flash进行基本的编程和擦除操作,通过了单模块的功能仿真和系统验证。