The role of computer systems in organizational decision making

Decision making is regarded as a key feature of managerial activity. As a result, a considerable amount of research activity has been undertaken that aims to enhance understanding and to improve on the decision‐making process within organizational settings. This research has been paralleled by a technological response in the development of information and communication technology that is heralded by many for its significant potential for improving decision making in terms of both efficiency and effectiveness. This paper examines the complex nature of decision making within organizations and examines the extent to which computer systems may provide effective managerial support in the face of increasing organizational complexity.     

An analytical technique to find approximate solutions of nonlinear damped oscillatory systems

Combining Krylov-Bogoliubov-Mitropolskii (KBM) and harmonic balance methods, an analytical technique is presented to determine approximate solutions of nonlinear oscillatory systems with damping. The first approximate perturbation solutions in which the unperturbed solutions contain two harmonic terms agree with numerical solutions nicely even if the damping force is significant. With suitable examples it has been shown that the combination of classical KBM and harmonic balance methods sometimes fails to measure satisfactory results; but the combination of extended KBM method (by Popov) and harmonic balance method always give the desired results. The method is illustrated by several examples and the solutions are compared to some existing solutions.     

计算机病毒的防范

计算机病毒技术的发展迫使反病毒技术的发展,病毒制造者不断更新技术,两者相互制约,螺旋上升式地不断提高各自的水平.本文就如何防范计算机病毒进行了探讨.     

The skewness of computer science

Computer science is a relatively young discipline combining science, engineering, and mathematics. The main flavors of computer science research involve the theoretical development of conceptual models for the different aspects of computing and the more applicative building of software artifacts and assessment of their properties. In the computer science publication culture, conferences are an important vehicle to quickly move ideas, and journals often publish deeper versions of papers already presented at conferences. These peculiarities of the discipline make computer science an original research field within the sciences, and, therefore, the assessment of classical bibliometric laws is particularly important for this field. In this paper, we study the skewness of the distribution of citations to papers published in computer science publication venues (journals and conferences). We find that the skewness in the distribution of mean citedness of different venues combines with the asymmetry in citedness of articles in each venue, resulting in a highly asymmetric citation distribution with a power law tail. Furthermore, the skewness of conference publications is more pronounced than the asymmetry of journal papers. Finally, the impact of journal papers, as measured with bibliometric indicators, largely dominates that of proceeding papers.     

Blind estimation of carrier frequency offset for OFDM systems with time-varying DC offset

Orthogonal frequency division multiplexing (OFDM) has been widely adopted in radar and communication systems. High sensitivity to carrier frequency offset (CFO) is one of the major drawbacks of OFDM. CFO estimation for OFDM systems had been extensively studied and various algorithms had been proposed. However, the established algorithms may be compromised by the adoption of direct-conversion architecture and multi-mode low noise amplifier in the OFDM receiver, which introduces time-varying direct current offset (TV-DCO) into the system. In our previous study, we developed an eigen-decomposition based estimation algorithm, which is robust to TV-DCO but suffers from performance degradation under low to medium signal-to-noise ratio and requires high computation efforts. To address those issues, we in this paper propose a novel blind CFO estimation algorithm. By making use of the second order differential filtering and subspace method, the proposed algorithm achieves great performance improvement with reduced complexity. The performance of the proposed algorithm is demonstrated by simulations.     

A combined time and frequency domain method for model reduction of discrete systems

A new combined time and frequency domain method for the model reduction of discrete systems in z-transfer function is presented. First, the z-transfer functions are transformed into the w-domain by the bilinear transformation, z = (1+w)/(1?w). Then, four model reduction methods—Routh approximation, Hurwitz polynomial approxima- tion, stability equation, and retaining dominant poles—are used respectively to reduce the order of the denominator polynomials in the w-domain. Least squares estimate is then used to find the optimal coefficients in the numerator polynomials of the reduced models so that the unit step response errors are reduced to a minimum. The advantages of the proposed method are that both frequency domain and time domain characteristics of the original systems can be preserved in the reduced models, and the reduced models are always stable provided the original models are stable.     

The clash of interests in computer information services

The University of London is a federal body consisting of over sixty colleges and institutes. These institutions differ in size, function and the degree of autonomy. Each institution has at least one library, some colleges have departmental libraries of considerable independence from the main library. There are five major computer centres within the University, with large resources in hardware and specialist staff, and with many years of experience in the provision of services to the wide population of the University. A Central Library Resources Co-ordinating Committee was formed in 1972 to coordinate the rich documentary resources of the University and to encourage the transfer and dissemination of information accumulated in its libraries. Under its administration, a Central Information Service headed by a Senior Information Systems Officer was initiated in October 1974. Its first task has been to undertake a large evaluation study of computer information services. Academic staff and postgraduate students have been exposed to a variety of experimental services and the impact of these services on the users has been assessed. Out of this work have come recommendations for continued provision of these services to the University in a cost-effective way. The paper considers the successes and setbacks of the project, and the reactions to it of the various parties involved—users, information officers, librarians and computer staff. The conflicts which arose during implementation of the project are discussed. They were caused by economic stringency at the University, technological changes introduced into libraries, and problems of charging for new computerised services.     

The role of pragmatic arguments in computer ethics

The purpose of this paper is to stress the importance of pragmatic arguments if we are to reach overlapping consensuses across cultural and disciplinary borders. An analytical distinction is made between, on the one hand, arguments based on socio-political or philosophical presuppositions, and on the other hand, pragmatic arguments. The latter are (as far as possible) detached from culture-specific or disciplinary presuppositions. I will mainly focus on the issue of regulation and surveillance on the Internet, and put forward a selection of pragmatic arguments for why widespread regulation and surveillance ought to be avoided. These arguments are intended to reach the same conclusion as arguments that are based on socio-political and philosophical presuppositions, with the aim of creating overlapping consensuses.     

The response of liver lipid peroxidative and antioxidant defense systems of protein undernourished rats to liver regeneration

The response of liver lipid peroxidative and antioxidant defense system of protein undernourished rats to liver regeneration induced by partial hepatectomy was examined in rats. Animals were divided into four groups; A,B,C and D of four animals each. Animals in group A were maintained on 16% casein diet while those in groups B, C and D were placed on low-protein diet (5% casein) for fourteen weeks and fed ad libitum. 72 hours before sacrifice, partial hepatectomy was carried out on animals in group D while animals in group C were sham-operated. The results show that protein undernutrition induced an increase in lipid peroxidation but reduced catalase activity, glutathione level and superoxide dismutase activity when compared with well-nourished rats. Liver regeneration however, resulted in significant increases in lipid peroxidation and catalase activity but significant reductions in glutathione level and superoxide dismutase activity in protein undernutrition rats when compared with their sham-operated counterparts. These results suggest that liver regeneration induced by partial hepatectomy exacerbates lipid peroxidation in protein undernutrition rats and that Catalase plays a major role in the mopping up of reactive oxygen species generated following liver regeneration in partially hepatectomised protein undernutrition rats.     

Networked load frequency control of multi-area uncertain power systems via adaptive event-triggered communication scheme

Load frequency control of power systems is a very important approach to keep stability and security. Unfortunately, the traditional load frequency control is not effective because of the introduction of communication networks in multi-area power systems. In order to overcome this difficulty, sampling-based load frequency control for multi-area power systems is studied via an event-triggered detector. Unlike published works, an adaptive law for event-triggered scheme is given. Since multi-area power systems with event-triggered scheme are hybrid systems, there are a lot of challenges for analysing load frequency control problem. Some lemmas and a new Lyapunov function are developed to overcome these challenges. The obtained stability and stabilization criteria can provide a tradeoff to balance the required communication resources and the desired control performance. Numerical examples verify effectiveness of the obtained results.     

人工智能计算机的发展困境

上个世纪八十年代,第五代计算机,也就是人工智能计算机的研究曾热极一时,然而时至今日,已经鲜有人提起第五代计算机了。本文对第五代计算机的主要特征进行了描述,从第五代计算机的核心技术…人工智能入手,对第五代计算机研究陷于困境的原因进行了探讨。在此基础上,对于人工智能的发展前景做出了自己的判断。     

中职计算机专业学生顶岗实习之探析

探讨了中等职业技术学校计算机专业学生顶岗实习的意义、现状以及存在的主要问题,并提出了一些建设性的对策和措施。     

高职计算机教学改革设想

当前高职计算机专业开展得如火如荼,每年的高职计算机专业毕业生日益增多,然而他们的就业形势却不容乐观.根据社会调研结果,并不是此类人才已达到饱和,恰恰相反的是非常紧缺,其中症结是我们培养的毕业生根本达不到社会所需要的技能水平.究竟哪个环节出了问题?我想我们的教学难辞其咎!高职计算机教学改革势在必行!     

计算机仿真在实验教学中的应用

计算机仿真是应用电子计算机对系统的结构、功能和行为以及参与系统控制的人的思维过程和行为进行动态性比较逼真的模仿。本文主要介绍了计算机仿真的一些基本概念,并以电子商务实验教学为例来讲述计算机仿真在实验教学中的应用。     

企业技术创新评价的计算机支持系统

本文对企业技术创新进行了系统分析，设计了具有可操作性的企业技术创新评价指标体系，并介绍了基于数据包络分析（DEA）方法而开发的企业技术创新评价的计算机支持系统。     

在非计算机专业计算机语言教学中强化素质教育初探

将素质教育思想融入计算机语言教学需尊重科学认知规律，包括教材的合理性、授课内容和方式的设计、教师自身思维的开放。改进了教学内容和实验方法，实施了加强结构化流程图的讲授与练习和实验中引用分层教学法。     

The time and frequency of unrelated diversification

Economic diversification—the process by which locations enter new economic activities—is known to be a combination of related and unrelated diversification. Related diversification is—on average—more frequent, but unrelated diversification is nevertheless considered important to avoid economic lock-in. Here, we study the frequency and timing of unrelated diversification using two international trade datasets at the country level. We find that related diversification is more frequent for countries at low levels of development but becomes less frequent as countries climb the complexity ladder. These findings contribute to our understanding of the role of relatedness in the diversification of economies at different levels of complexity.