在几何结构设计中采用遗传算法优化横向磁场永磁电机的转矩波形

在制造横向磁场永磁电机（TFPM）电机之前，应确定最大转矩的波形。通过调整TFPM电机的各项几何参数，可以使电机达到其最大转矩。一种基于人工智能的最优化方法可以使得每个极间隔都获得理想的转矩波形。本文给出了一种用于优化TFPM几何参数的遗传算法，该算法同样适用于其它结构的电机。     

用于简易变频器设计的新型扁平输入整流器

在制造横向磁场永磁电机（TFPM）电机之前，应确定最大转矩的波形。通过调整TEPM电机的各项几何参数，可以使电机达到其最大转矩。一种基于人工智能的最优化方法可以使得每个极间隔都获得理想的转矩波形。本文给出了一种用于优化TEPM几何参数的遗传算法，该算法同样适用于其它结构的电机。     

Perspectives on next generation mobile

Employees in today’s enterprises are requesting their employers to allow them to work in a flexible manner. Work is no longer a place to go to but an activity to be undertaken. With developments in technology, the activity can be undertaken whenever and wherever it is convenient for the employees. Increasing demands by employees to be able to work in this way creates a tension within the enterprise as CIOs and finance officers strive to manage the costs and the infrastructure required to support this way of working. Over time, this situation will change as technology allows users to roam securely and seamlessly between networks accessing the required applications and information from a single suitably enabled device. This will tend to reduce the underlying costs as the best connection can be used. Service management will remain a challenge but become a better understood problem as the ’stove-pipe’ nature of current solutions is removed. For this change to be brought about, some enabling technologies have to be put in place. This paper considers issues surrounding next generation mobile solutions and shows how converged services can be used to deliver the vision of being able to work from any place, at any time. Consideration is given to how roaming from fixed to wireless networks can be achieved by reusing already established authentication principles that are now deployed in wide area wireless networks. In order to do this, open methods of managing user identity need to be devised and implemented and approaches to this are also discussed. The paper concludes with a consideration of some of the research challenges that remain to be solved. HP     

The Assignment of CDMA Spreading Codes Constructed from Hadamard Matrices and Almost Bent Functions

Almost bent functions and Hadamard matrices can be used to construct spreading codes for code-division multiple-access (CDMA) systems. Four specific Hadamard matrices can be constructed and each one can be divided into eight octants in such a way that spreading codewords from certain pairs of octants have zero correlation. It is possible to assign these octants to a regular tessellation of hexagonal cells in such a way that there is zero correlation between adjacent cells, small correlation between non-adjacent cells and a large codeword re-use distance. If synchronous CDMA is used in a satellite system, interference is reduced in comparison with the use of a single Hadamard matrix. In this case the regular hexagonal tessellation is usually a good model of the areas covered by satellite spot beams. The same approach can be advantageous when the Hadamard matrices are used to construct loosely synchronized codes for a terrestrial system. The tessellation of cells is unlikely to be a regular hexagonal tessellation and the question arises of whether an assignment to an irregular tessellation with these properties can be found. In this paper a positive answer is given to this question, confirming that the approach is applicable to a terrestrial system.     

Cryptographic Authentication of Time-Invariant Quantities

With any strong cryptographic algorithm, such as the data encryption standard (DES), it is possible to devise protocols for authentication. One technique, which allows arbitrary, time-invariant quantities (such as encrypted keys and passwords) to be authenticated, is based upon a secret cryptographic (master) key residing in a host processor. Each quantity to be authenticated has a corresponding precomputed test pattern. At any later time, the test pattern can be used together with the quantity to be authenticated to generate a nonsecret verification pattern. The verification pattern can in turn be used as the basis for accepting or rejecting the quantity to be authenticated.     

Diagnosis of single faults in bitonic sorters

Bitonic sorters have recently been proposed to construct along with banyan networks the switching fabric of future broadband networks. Unfortunately, a single fault in a bitonic sorter may have disastrous consequences for the switching system. Therefore, a bitonic sorter must be proved to be free of faults before it can be used. We study the topological properties of bitonic sorters and present an efficient fault diagnosis procedure to detect, locate, and identify the fault type of single faults. Our diagnosis procedure can detect most single faults in two tests. Faults which cannot be detected in two tests can always be detected in four tests. Several binary search techniques are developed to locate a faulty sorting element (i.e. a 2×2 sorter)     

On the compensation of the nonideal NIC

This letter shows that the criteria for a two-port to be a nonideal NIC in terms of its h parameters should be applied to both orientations of the two-port. Alternatively, a different set of conditions should be used if the two-port is to remain in the same orientation.     

Making the best use of the airways: an important requirement formilitary communications

The growing communication demands of modern warfare must be met with the fixed resources of the electromagnetic spectrum. When an armed force is deployed, frequencies must be assigned, within a restricted bandwidth and in a short time-scale, to its many (e.g. 400) radios so as to minimise the interference between them. There are too many ways in which a frequency allocation can be made for them all to be evaluated; instead the best assignment that can be discovered within a limited time must be chosen. This is typical of a class of problems known as combinatorial optimisation problems. This paper discusses some of the methods which can be used for solving such problems and presents results for a hybrid algorithm based on construction methods, tabu search and genetic algorithms which has been developed at DERA-Malvern     

Minicomputer applications in the seventies

The purpose of this report is to give the reader, by means of specific application examples, an overview of the extreme versatility of the minicomputer. The basic system configurations that will be described may be adapted, by analogy, to many other tasks. In this manner we hope to stimulate the reader to think about ways in which a minicomputer might be able to do a job for him at less cost, in less time, in a more thorough manner, or more reliably than that job could be done?if it could be done at all?without the minicomputer. It is beyond the intended scope of this report to discuss minicomputer architecture, to describe in detail commercially available minicomputers, or to attempt to offer detailed guidelines for the selection of a specific minicomputer model for a system.     

The social impact of technology on millennials and consequences for higher education and leadership

Millennials interact with technology like no other generation before them and this is affecting how they want to be taught in higher education and how they want to lead and expect to be led in organizations, after graduating. Though stating that they want to be enlightened in academia, some qualitative comments from millennials indicate the opposite, namely that they want to be prepared but also to be kept naïve as to what business really entails. This is expected to help keep motivation levels high, as motivation is seen to be the key element to success in life. Millennials expect also to be led authentically and to be treated as valued human beings. This is in contrast to the current autocratic leadership profile found predominantly in Portuguese organizations, at the time of writing. This study had a sample of one hundred and eleven millennial students who answered a survey on attitudes towards leadership and their desired approach to higher education. Three interviews with seasoned executives were also performed, to establish a contrast and see other perspectives.With this research, we conclude that we may be in the presence of a hard working millennial generation, contrary to previous research findings which has indicated that they are lazy. Finally, information technology (IT) is a precious partner in class, in particular Padlet.com, Moodle, and online News Forums, as well as the challenge to create original videos about course content. Future research should focus on how technology has made society more transparent with employees wanting more democratic leaders in times when hierarchies are seen to hinder rather than aid productivity levels.     

旋转靶标平行光束空间交叠区域的分析与验证

分析了旋转靶标工作时平行光束在空间的交叠区域,提出了该区域为可准确定义的纺锤形圆锥体区域.使用旋转靶标测试时,只需将被测设备的方位俯仰视轴交点放置在此区域内即可.使用旋转靶标对摆放在纺锤形圆锥体区域内不同位置的某型光电设备进行了多次测角和跟踪精度的验证试验,测试值标准差和平均差的最大值均远小于该型设备的对应指标.测试结果表明,只要将被测设备方位俯仰视轴的交点放置在以旋转靶标光锥顶点为中心的纺锤形圆锥体区域内,由摆放位置偏差引入的测试误差就极其有限.测试结果的离散程度很低,重复性很好,能满足测试应用的需求.验证试验证明了纺锤形圆锥体区域定义的正确性,表明该定义可作为测试时判断被测设备是否与旋转靶对准的理论依据.     

Practical limitations to a natural mode characterization of electromagnetic transient response measurements

Practical limitations arising from limited signal-to-noise ratios in actual transient electromagnetic measurements limits the number of natural modes which can be extracted from such measurements. This number is shown here to be three to six for a complex scatterer, in this case an aircraft, five for a "fat" cylinder and thin wire. This is for double exponential waveform excitation of the aircraft and step function excitation of the fat cylinder and thin wire. A few more modes can be resolved if the excitation is altered so as to provide more high frequency energy, as can be accomplished by changing the step excitation to a delta function excitation, or by signal conditioning, for example making a derivative measurement that emphasizes the high frequency response. Even so, far fewer modes can be resolved experimentally than can be predicted. Experimental electromagnetic transient response measurements should therefore be made with these practical limitations in mind.     

Performance analysis by simulation of floating-gate MOSFETs applied on a bidirectional associative memory architecture

Floating-gate MOSFETs (FGMOSFETs) are devices that can be electrically programmable and have a non-volatile characteristic. This feature can be adopted to configure a basic cell performing as a variable resistance that can be applied in artificial neural networks as a synapse. Based on a simple model and considering the coupling coefficient of the structure as the gain of a voltage controlled voltage source, the electrical characteristics of a floating-gate MOSFET can be simulated in PSpice and an artificial neural net, such as the bidirectional associative memory (BAM), can be implemented. Therefore a performance analysis of the net may be done with different sets of threshold voltages for the FGMOSFETs configured as a CMOS inverter used as a synapse. The objective is to know pattern pairs in a bidirectional way. The result is a correlation matrix for the BAM as a function of an electrical parameter of the devices, which is directly related to the respective matrix calculated by the matrix dot product, using the method outlined by Kosko.     

A fast software one-way hash function

One way hash functions are an important cryptographic primitive, and can be used to solve a wide variety of problems involving authentication and integrity. It would be useful to adopt a standard one-way hash function for use in a wide variety of systems throughout the world. Such a standard one-way hash function should be easy to implement, use, and understand; resistant to cryptographic attack, and should be fast when implemented in software. We present a candidate one-way hash function which appears to have these desirable properties. Further analysis of its cryptographic security is required before it can be considered for widespread use.     

A Multichannel Event Timer for Real-Time Laboratory Computer Systems

In this paper we describe an event timer which was designed to be used in a neurophysiological laboratory. The timer is used with an LSI 11/03 computer and interfaces with the computer through a standard Digital Equipment Corporation DRV 11 interface board. The time of occurrence of pulses on up to 15 different input lines can be recorded with an accuracy determined by the time base of the timer, which can be varied from 1 to 5000 gs. In order to record events that occur simultaneously on different channels or in very rapid succession, we employ a first-in, first-out (FIFO) register as a buffer. An input scanner allows one timer to be used for timing events that occur on several input channels. This device may be useful in other applicatoins in which the time of occurrence of multiple events needs to be accurately timed.     

The Use of Moment Space Bounds for Evaluating the Performance of a Nonlinear Digital Communication System

Certain moments of the output of a bandpass nonlinear system whose input is a stationary Gaussian random process will be used to evaluate the performance (i.e., the average probability of error) of the system. The main application of this procedure is the analysis of a frequency translating saturating satellite link. The basic analytical technique to be employed will be the use of moment space bounds, it will be shown that by using at most a two-dimensional Gaussian quadrature formula to perform a numerical integration, the bounding procedure presented in this paper can be used in a relatively straightforward manner with virtually any bounded bandpass nonlinearity. Numerical results Corresponding to a hard limiter with only an AM/AM characteristic will be presented, as well as results corresponding to a soft limiter with both AM/AM and AM/PM characteristics. In the latter model, the effects of intersymbol interference will also be included. However, computationally, the procedure is only feasible for a small number of interfering terms.     

Valuing customers

This paper considers the metric of customer lifetime value as a way of placing an expected future value on a company’s customers. This approach looks at the fundamental contribution a customer makes to a company’s profits. The basic concept is useful in its own right, but it also allows an analogue between a customer and the equity of the company to be drawn. This allows the customer to be considered as a revenue-producing asset. Financial engineering tools, such as portfolio and options theory, then become natural means to analyse the customer’s value further. In particular, the uncertainty in the future profits created by a customer can be shown to create an added dimension to the value a customer brings to the business. The results from these analyses can be used to guide customer relationship strategy. Better decisions on the levels of investments in customers and customer services, and their timings, can also be made.     

Piezoelectric oscillating cantilever fan for thermal management of electronics and LEDs — A review

This review discusses piezoelectric fans and their feasibility in a cooling of electronics components and LEDs. The discussion will be restricted to fans based on an oscillating cantilever, the construction which is best known. Other possible piezoelectric fan constructions will be just shortly mentioned. Since the invention of a piezoelectric fan in late 1970s, at least hundreds of science papers have been published about them. A general level presentation of the subject and a summary of the research outcomes will be presented. The construction and operation principles of a piezoelectric fan will be presented. An introduction to piezoelectric materials will be given. The most important equations covering the oscillation of a cantilever beam and the equations for designing fan's geometry will be presented. The generated air flows of a single piezoelectric fan will be issued. This subject will be approached by executing some computational fluid dynamics (CFD) simulations. Use of an air nozzle can force the air vortices closer to laminar flow and improve the cooling effect. The rather weak air flow of a single fan motivates to use multiple fans. A large number of studies have been published about multiple fan constructions. A piezoelectric fan will be compared with a conventional radial fan. An introduction to the electrical parts of a piezoelectric fan will be given. An experimental work demonstrating the use of a piezo fan for electronics cooling will be executed.     

Traffic engineering in next-generation optical Networks

In this article traffic-engineering issues regarding network survivability, traffic grooming, impairment-aware routing, virtual-topology engineering, and coordination among multiple layers of network architecture will be reviewed for next-generation optical networks based on Wavelength-Division Multiplexing (WDM). Due to the recent progress and development of WDM technology, increasing traffic demands can be readily accommodated in the next-generation optical networks. In spite of the huge amount of capacity (e.g., OC-192) provided by a WDM channel, enhanced network services and network performance improvement can only be achieved with efficient traffic-engineering mechanisms. The fault-tolerant function is essential in order to provide seamless services to users by protecting their traffic against failures in the optical network because many connections can be carried on a fiber. Because the capacity of a WDM channel is very large, its bandwidth may not be efficiently utilized by a single connection. Hence, low-rate user connections need to be efficiently aggregated through the traffic-grooming scheme. An intelligent routing algorithm is especially necessary in the optical network where signal impairments due to device imperfections might degrade the signal quality. In addition, the virtual network connectivity (topology) should be flexibly maintained such that dynamic changes to the traffic demands can be easily absorbed, which can be implemented by the virtualtopology engineering method in a WDM network. As the dominant usage of Internet Protocol (IP) of the Internet is expected to reside directly above the WDM layer in the future network, the coordinated trafficengineering scheme should be deliberately designed for the multi-layer network by judiciously choosing where to put many overlapping functions in the different network layers.     

In-Band Generation of Synchronous Linear Data Signals

In-band generation of synchronous linear data signals eliminates the need for preliminary generation of a baseband signal and sharp cutoff filtering. However, the ratio of carrier frequency to pulsing rate must, in general, be an integer if the signal is to be produced by successive pulsing of a single fixed filter. As a consequence, a singlesideband signal of bandwidthWand transmission rate2Wmust occupy the frequency band [2NW,(2N +1)W],Nan integer, when it is generated from a single fixed filter. A partial-response signal satisfying this condition is described in this paper. A further analysis demonstrates that a finite number of fixed filters can be used to produce a pulse train in any band where the ratio of carrier frequency to pulsing rate is a rational number. Since this relaxed condition allows any transmission band to be approximated to an arbitrary degree of accuracy, frequency translation can be avoided. A single transversal filter with periodically varied tap weights is shown to be a practical realization.