An algorithm for fault-tree probabilities using the factoring theorem

This paper describes an algorithm (and implementation of the algorithm) called FACTOR for determining the probability of the top event in a fault tree. The methodology is exact and does not involve cut sets. It is primarily a top-down recursive approach that judiciously uses “factoring” in the form of the elementary equation P(F) = P(E) P(F|E) + P(E^c) P(F|E^c). While indiscriminate use of conditional probabilities in this form would be very inefficient, examples from the current literature show that the algorithm FACTOR often gives exact results in times comparable to recently published approximation methods implemented on mainframe computers. FACTOR is portable and was implemented and tested on a Macintosh microcomputer.     

Reliability of directed networks using the factoring theorem

The authors present a framework in which the factoring theorem can be used in conjunction with other network reductions and simplifications to determine the reliability of source-to-sink communication in a directed network. On published test networks, the proposed microcomputer implementation of this framework solves the two-terminal reliability problem substantially faster than existing implementations of other current algorithms     

A new algorithm for factoring polynomials

A new algorithm for finding the roots of polynomials is presented. The method is based upon an accurate first approximation to a root which is then used to initiate an iterative solution. The method is reliable, rapid, has a high order of convergence, and excellent convergence in the large.     

一种实用的HDTV信道设计方案及实现

提出了一种实用的高清晰度电视接收机信道处理方案,并对该方案所涉及的关键技术进行了详细的探讨,在实践基础上阐述了设计方案实现的方式。     

Generic control method of multileg voltage-source-converters for fast practical implementation

A generic and simple control method is suggested for any multileg voltage-source-converter. A specific coding yields an inversion table allowing a fast practical implementation. Phase-to-phase voltage references have to be defined for such a table. This original control strategy is validated by experimental results for two-leg, three-leg, four-leg, and five-leg structures supplying balanced and unbalanced multiphase loads.     

A key distribution system equivalent to factoring

We propose a variation of the Diffie and Hellman key distribution scheme for which we can prove that decryption of a single key requires the ability to factor a number that is the product of two large primes. The practical advantage of such a scheme is that it will still be secure if the cryptanalyst knows a very fast algorithm for either factoring or computing discrete logarithms, but not for both. Using these keys in the ElGamal public-key cryptosystem provides a scheme for which the decryption of a message requires the ability to factor the modulus and break the original Diffie and Hellman scheme. Research supported in part by grants from the USC Faculty Research and Innovation Fund and the National Security Agency.     

Comparison of practical methods for an efficient FPGA implementation of STAP

In this paper, practical methods for an efficient field programmable gate array (FPGA) implementation of space-time adaptive processing (STAP) are investigated and compared. The most important part for calculating the STAP weights is QR decomposition (QRD) which can be implemented using the modified Gram–Schmidt algorithm. Investigations show the method that uses QRD with less computational burden and leads to more effective implementation. Its structure parameterised with vector size to create a trade-off between hardware and performance factors. For this purpose, the modifications on QRD-MGS are performed in order to speed increasing. Then, the calculation of STAP weight vector was implemented. The implementation results show that decreasing vector size decreases the resources utilisation, computational burden and consumption power. However, computation time increases slightly, but the update rate of the STAP weights is maintained. For example, weights in the system with 6 antenna arrays, 10 received pulses and 200 range samples computed in 262 µs by vector size of 17 on the Arria10 FPGA the maximum of which is 155 µs are related to QRD-MGS and 107 µs is related to other parts. Therefore, QRD-MGS is the most important part in calculation of the STAP weight vector and its simplifying led to an efficient implementation.

Abbreviations: Computation time, Field programmable gate array, QR decomposition, Space time adaptive processing     

Comparison of practical methods for an efficient FPGA implementation of STAP

This study investigated and compared the practical methods used for the efficient Field- Programmable Gate Array (FPGA) implementation of space-time adaptive processing (STAP). The most important part of calculating the STAP weights is the QR decomposition (QRD), which can be implemented using the modified Gram-Schmidt (MGS) algorithm. The results show that the method that uses QRD with less computational burden leads to a more effective implementation. Its structure was parameterised with the vector size to create a trade-off between the hardware and performance factors. For this purpose, QRD-MGS algorithm was first modified to increase the speed, and then the STAP weight vector was calculated. The implementation results show that decreasing the vector size decreases the resource utilisation, computational burden and the consumption power. While the computation time increases slightly, the updated rate of the STAP weights is maintained. For example, the STAP weights in a system with 6 antenna arrays, 10 received pulses and 200 range samples computed in 262 µs using a vector size of 17 on the Arria10 FPGA that has a maximum of 155 µs correlates to the QRD-MGS algorithm and 107 µs correlates to the other parts. Therefore, QRD-MGS algorithm is the most important component of the calculation of the STAP weight vector, and its simplification leads to efficient implementation.     

基于剩余定理的数字干涉仪设计与实现

通过介绍一套外场应用条件下基于剩余定理的多基线数字干涉仪系统设计、仿真、实现和实验结论,说明剩余定理应用于干涉仪设计具有较为严密的逻辑性和准确性。将数字接收技术引入干涉仪系统合理可行,并且保证了较高性能,符合电子对抗发展趋势,使系统设计方法更具借鉴意义。该干涉仪采用超宽带数字技术实现,数字中频带宽达到400 MHz,已应用于某单站定位试验系统,效果良好。     

《计算机实用操作英语》考试系统的设计与实现

本文探讨了"翻转课堂"教学模式下计算机实用操作英语教学中的课上考试系统的设计和实现,设计出了具有Office操作类题目判分、防作弊等功能的系统.通过使用考试系统,建立了课下学习和课堂考试的评价机制,为计算机英语教学改革提供了思路.     

Real-time implementation of optical OFDM transmitters and receivers for practical end-to-end optical transmission systems

Real-time optical OFDM transceivers are successfully demonstrated for the first time, which support 1.5 Gbit/s transmission over 500 m 62.5/125 μm multimode fibres in an intensity-modulation and direct-detection system involving a directly modulated DFB laser. The implemented transceivers only use standard commercially available components.     

A sampling theorem for shift-invariant subspace

A sampling theorem for regular sampling in shift-invariant subspaces is established. The sufficient-necessary condition for which it holds is found. Then, the theorem is modified to the shift sampling in shift-invariant subspaces by using the Zak transform. Finally, some examples are presented to show the generality of the theorem     

A coding theorem for the discrete memoryless broadcast channel

A coding theorem for the discrete memoryless broadcast channel is proved for the case where no common message is to he transmitted. The theorem is a generalization of the results of Cover and van der Meulen on this problem. The result is tight for broadcast channels having one deterministic component     

A strengthening of the Assmus-Mattson theorem

Let w₁=d,w₂,…,w _s be the weights of the nonzero codewords in a binary linear [n,k,d] code C, and let w' ₁, w'₂, …, w'₃, be the nonzero weights in the dual code C1. Let t be an integer in the range 0<t<d such that there are at most d-t weights w'_i with 0<w'_i ⩽n-t E. F. Assmus and H. F. Mattson, Jr. (1969) proved that the words of any weight w_i in C form a t-design. The authors show that if w₂⩾d+4 then either the words of any nonzero weight w_i form a (t+1)-design or else the codewords of minimal weight d form a {1,2,…,t,t+2}-design. If in addition C is self-dual with all weights divisible by 4 then the codewords of any given weight w_i form either a (t +1)-design or a {1,2,…,t,t+2}-design. The proof avoids the use of modular forms     

A practical electrode-array myoprocessor for surfaceelectromyography

A new myoprocessor is described which produces a relatively smooth and accurate measure of a muscle's electrical activity during both slow and rapid movements. This is achieved partly by spatial averaging of weakly correlated EMG signals from electrodes distributed over the surface of the muscle.     

A practical strategy for EMC design

The introduction of the European EMC Directive has made it very important that engineers design for EMC in their products from the start. The paper describes a strategy to ensure that EMC aspects of design are considered in a logical sequence during development. This strategy is discussed, checklists for EMC design are introduced and a number of important design areas highlighted     

A practical classification-rule for software-quality models

A practical classification rule for a SQ (software quality) model considers the needs of the project to use a model to guide targeting software RE (reliability enhancement) efforts, such as extra reviews early in development. Such a rule is often more useful than alternative rules. This paper discusses several classification rules for SQ models, and recommends a generalized classification rule, where the effectiveness and efficiency of the model for guiding software RE efforts can be explicitly considered. This is the first application of this rule to SQ modeling that we know of. Two case studies illustrate application of the generalized classification rule. A telecommunication-system case-study models membership in the class of fault-prone modules as a function of the number of interfaces to other modules. A military-system case-study models membership in the class of fault-prone modules as a function of a set of process metrics that depict the development history of a module. These case studies are examples where balanced misclassification rates resulted in more useful and practical SQ models than other classification rules     

计算机专业实践能力培养方案设计与实践

计算机科学与技术专业是实践性较强的学科,但在如何培养学生实际动手能力方面还存在些不足。就培养学生专业实践主修能力,提出了较为明确详尽、极具操作性的训练方式、方法、考核标准及要求,希望能给相关专业的实践教学提供一些借鉴。