Optoelectronic switches and multigigabit 8:1 time multiplexer

Optoelectronic metal-semiconductor-metal (MSM) switches in InP were studied and used as sampling elements in a digital time division multiplexer. It was found that switch performance can range from the depletion-layer photodiode to the photoconductor regime as the activating light intensity increases. The multiplexer had an 8:1 ratio, a 2-V signal bias, >25-dB S/N, and a serial rate of at least 2.5 Gb/s. This multiplexer with its high S/N and the timing stability intrinsic to fiber delay lines will be advantageous for high-speed digital communications     

Optimal cost/performance design of ATM switches

This paper proposes a methodology for performing an evaluation and optimization of the cost of an ATM switching architecture under performance constraints given in terms of virtual connection blocking probability. An analysis of blocking networks is developed, and combined with known results concerning nonblocking networks, provides a theoretical model which relates traffic characteristics, network topology and blocking probability in a multirate/multiservice broadband environment. An analysis of the characteristics determining the cost of a generic ATM switch implementation follows. The model is oriented to optimize both the topological parameters and the speed advantage, with respect to the main cost factors of VLSI-based switching networks i.e., components count and complexity, interconnection costs     

The turn-on delay time of silicon p-n-p-n switches

The turn-on delay time of silicon p-n-p-n switches has been experimentally shown to be inversely proportional to gate currents in excess of the threshold value. Based on the measurements of bidirectional p-n-p-n switches, it is demonstrated that p-n-p-n structures with remote gating have inherently longer turn-on delay times than those of the conventional construction having the gate lead attached to a base region.     

Optimal and heuristic algorithms to synthesize lattices of four-terminal switches

In this work, we study implementation of Boolean functions with nano-crossbar arrays where each crosspoint behaves as a four-terminal switch controlled by a Boolean literal. These types of arrays are commonly called as switching lattices. We propose optimal and heuristic algorithms that minimize lattice sizes to implement a given Boolean function. The algorithms are mainly constructed on a technique that finds Boolean functions of lattices having independent inputs. This technique works recursively by using transition matrices representing columns and rows of the lattice. It performs symbolic manipulation of Boolean literals as opposed to using truth tables that allows us to successfully find Boolean functions having up to 81 variables corresponding to a 9 × 9-lattice. With a Boolean function of a certain sized lattice, we check if a given function can be implemented with this lattice size by defining the problem as a satisfiability problem. This process is repeated until a desired solution is found. Additionally, we fix the previously proposed algorithm that is claimed to be optimal. The fixed version guarantees optimal sizes. Finally, we perform synthesis trials on standard benchmark circuits to evaluate the proposed algorithms by considering lattice sizes and runtimes in comparison with the recently proposed three algorithms.     

On the blocking time distribution of core OBS switches

Given the bufferless nature of Optical Burst- Switched networks, data bursts are either transmitted or dropped; the latter typically occurs when all the wavelengths of a given output port are occupied. Clearly, the amount of time during which a given output port is blocked and cannot schedule incoming data bursts is a key performance measure of OBS networks. This work shows that, under Poissonian burst arrivals, the blocking time distribution of a given output port in an OBS node approaches the exponential distribution as the number of wavelengths increases. It is further shown that this behavior remains regardless of the size distribution of incoming bursts, and therefore, regardless of the burst-assembly algorithms employed at the border nodes. Finally, this result is also applied to the characterization of the amount of overspill traffic, that is, the number of bursts that arrive within a blocked period, and therefore must be either dropped or diverted over alternative routes.     

Simulation and interpretation of fast rise time light-activatedp-i-n diode switches

A simulation program and a comprehensive physical interpretation for risetimes and output powers of the long transit p-i-n diode under high and low optical-pulse excitations as well as at various impedances are presented. The physical interpretation explains the mechanisms of the switch risetime limitation in terms of the cancellation electric field due to separated photocarriers, the induced electric field with various RC time delays, and the optical-pulse energy risetime. Under high optical excitations and long circuit risetimes, the output risetime is determined only by the electric field cancellation time associated with the collapse of the total electric field and decreases with increasing optical-pulse excitation. This is in contrast to the case of low optical-pulse excitations where the risetime is determined by both the circuit risetime and the optical-pulse energy risetime     

Loss minimization control of permanent magnet synchronous motordrives

This paper aims to improve efficiency in permanent magnet synchronous (PM) motor drives. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current vector. The control algorithm of the current vector minimizing the electrical loss is proposed and the optimal current vector can be decided according to the operating speed and the load conditions. The proposed control algorithm is applied to the experimental PM motor drive system, in which one digital signal processor is employed to execute the control algorithms, and several drive tests are carried out. The operating characteristics controlled by the loss minimization control algorithm are examined in detail by computer simulations and experimental results     

Dual-mode behavior of silicon heterostructure switches with third-terminal control

The performance of three-terminal silicon heterostructure switches is examined. Different types of third terminal injection are considered. The device is seen to operate in both avalanche and punch-through modes under particular circumstances. The criterion for punch-through operation is developed.<>     

Distribution of base dopant for transit time minimization in abipolar transistor

A means to determine the doping profile minimizing base transit time in a bipolar transistor is presented, assuming that the width of the neutral base is held constant. It is found that the optimum profile is not close to the exponential decrease from emitter to collector predicted by earlier studies     

Optimum Ge profile for base transit time minimization of SiGe HBT

Optimization of the trapezoidal Ge profile to minimize base transit time of the SiGe bipolar transistor was examined. A closed-form equation to find the optimum point of the trapezoidal Ge profile for base transit time minimization as a function of temperature is derived. Experimental data published in the literature are used to compare the model predictions with measurement.     

Waiting time estimates in symmetric ATM-oriented rings with thedestination release of used slots

This paper considers the basic access mechanism in asynchronous transfer mode (ATM)-oriented rings which, like Orwell, ATM ring, and ALine, apply destination release of used slots. The released slots may be reused by the destination station, or in some protocols, they must be given to the next station. Such a mechanism can be modeled by a multiple-server multiqueue system, where switchover times between consecutive polling instants of the queues are nonzero. The server polls the queues according to a certain polling discipline, which is dependent on the service time. This paper presents approximate mean minipacket waiting times in such systems. The approximation is based on a polling queueing model with Markovian server routing. Poisson arrivals and a symmetric workload model for minipackets having a full and partial traffic matrix are assumed. The performance characteristics are compared between the alternative options     

Frame synchronization in a photonic network of time multiplexedspace switches via a feedback scheme

A method for frame synchronization in a photonic network of time multiplexed space switches is presented. The method, which is based on a feedback scheme, is first introduced for frame synchronization in a single-switch configuration. The feedback scheme is then extended to both hierarchical (tree topology) and nonhierarchical (general topology) multiswitch configurations. Using this feedback scheme has the advantage of providing a mechanism for frame synchronization to be achieved initially, without the need for accurate transmission time measurements, and allowing synchronization to be maintained within very tight bounds. The methods presented require additional electronics at the switches, but electronics only for control purposes, not in the path of the information bits. However, optical delay elements are needed in the path of information bits on some links of the network. The proposed schemes also reduce the amount of synchronization equipment needed, compared to other methods     

On applying a minimization technique to the harmonic elimination PWM control: the bipolar waveform

The well-known harmonic elimination pulse-width modulation (HE-PWM) method for inverter control is revisited. The HE-PWM waveform presents many challenges. It has multiple solutions that not only need to be found as easily and as fast as possible, but must also be evaluated in order to identify the best technique when overall harmonic performance is concerned. Algorithms presented so far rely on starting values that are close to the exact solutions to ensure convergence. A new method based on resultant theory promises limited success since it can only work when a small number of harmonics is to be eliminated. In this paper, it is shown that a minimization technique in combination with a random search results in a relatively simple approach that finds all possible sets of solutions. It is confirmed that numerous independent sets of solutions exist and the ones that offer better harmonic performance are identified. Three cases are reported in detail, including when two, four and six nontriplen odd harmonics are to be eliminated.     

Optimal feedback control of direct-current motors

A methodology for real-time speed control of a thyristor-driven DC motor in the presence of measurement noise and load torque disturbance is developed. An optimal state feedback controller using the Kalman-filter state estimation technique is derived. This is followed by an adaptive control algorithm to compensate for the effects of noise and disturbance. These two algorithms working together are capable of providing a very high-speed regulation and dynamic response over a wide range of operating conditions. Simulated responses using an i80386-based PC with a mathematics coprocessor are presented to highlight the effectiveness of the control strategy     

Optimal control of three-level PWM inverters

An harmonic loss-minimized optimal PWM strategy for three-level inverters is investigated. The different PWM methods for low-, middle-, and high-speed regions are presented. It is shown that, for three-level inverters, the optimized strategy in all speed regions differs from the optimal PWM strategy of two-level inverters. The developed optimal control ensures a minimum of harmonic losses for a predetermined number of commutations of three-level PWM inverters and for a given value of the fundamental harmonic voltage     

基于模糊控制的重载AGV控制系统设计

为了提高盾构管片厂的生产效率,降低生产制造环节中的运输成本,设计了一套AGV车载控制系统.车载控制系统主要包括主控制器模块、无线通信模块、磁导航模块、驱动模块、安全装置模块和定位模块等.针对AGV在沿规定路线行驶时,由于外界不确定因素导致AGV偏离既定路线的问题,设计了二维模糊控制器来进行轨迹纠偏.在盾构管片生产厂进行...     

基于JADE的数据库自适应负载控制分析

传统DBA数据库控制方法对系统参数进行设置和配置时,存在控制效率低以及能耗高的问题。提出基于JADE的数据库自适应负载控制方法,设计以JADE平台为基础的数据库自适应负载控制系统。系统由搜索和查询两部分构成,通过Agent之间相互协作来完成总体系统的负载控制。通过数据库爬虫Agent在数据库中搜集信息,形成原始数据库;应用KNN算法对原始数据库进行分类,实现数据库负载控制。查询部分通过JSP页面中的用户接口Agent实现与用户的交互;采用JDBC桥技术实现查询Agent对数据库的访问。实验结果表明,采用所提方法控制数据库负载,可提高数据库的实现价值、吞吐率以及资源利用率。     

Multichannel operation of AOTF switches: reducingchannel-to-channel interaction

An acoustooptic tunable filter (AOTF) can be used as a multichannel wavelength-routing switch; however, switching efficiency decreases and the switched wavelength channels shift toward each other when neighboring channels are selected simultaneously. We explain the cause of this behavior and show how to reduce the degradation in switch characteristics using a combination of passband flattening and counterpropagating acoustic waves     

Optimal automatic control of multistage production processes

Today's high-tech industries produce complicated products involving many processing steps. The usual approach of modeling and controlling each of these steps in isolation is re-evaluated. This work develops a data model of synchronized observations collected from several stages of a multistage manufacturing process, and proposes an across-stage automatic control scheme for adjusting nonstationary process drifts. The proposed controller applies dynamic programming tools to optimize multiple goals specified for individual process stages and possible mismatch between stages. Several examples and simulation studies demonstrate that the proposed method is a valuable tool for improving semiconductor manufacturing quality.     

Optimal efficiency control of switched reluctance generators

This paper investigates the problem of optimal control for accomplishing maximum energy conversion in switched reluctance generators. A controller that determines the optimal turn-on and turn-off angles in the mode of single-pulse operation is proposed. The structure of the controller and its implementation are simple, since the knowledge of the magnetization curves is not required. The suggested generator drive operates in a wide speed range and provides constant dc-link voltage at a desired value, with maximum energy efficiency. Simulation and experimental results are presented to validate the effectiveness and the resulting improvements of the proposed control scheme.