论网络中的一种差错检测技术--CRC

CRC是目前网络中普遍采用的一种检测码 ,只有真正了解和掌握它 ,才能选择合适的CRC ,使传输帧达到冗余位少、漏检率低的目的 ,从而提高传输效率。本文从CRC的理论基础、冗余位的产生方法、性能分析及实现手段等方面作了全面的剖析     

DS-CDMA的MIMO系统中的空时多用户检测

Space-time signal processing based on multiple-input multiple-output（MIMO） systems is an active research field in which interfering signals are cancelled and multiuser detection is achieved using space diversity. In a Rayleigh fading channel, space-time block cedes using multiple transmitting antennas can improve system performance and reduce bit-error-rate for multiuser detection. In this paper, several antenna configurations are designed for DS-CDMA communication in MIMO systems. Space-time linear multinser detection and space-time serial interference cancellation multiuser detection are simulated. Bit-error-rate and computation complexities of the two methods are compared. Conclusions are given in the end.     

利用一种新LDPC码的编码OFDM系统性能分析

提出了一种新的构造LDPC码的方法, 并把用该方法产生的LDPC码应用到编码正交频分复用(OFDM)系统中进行了研究. 该方法拓展了单位阵移位构造的LDPC码, 它利用简单的不等式可确保在置换单位阵构造中不会产生Tanner图中的短圈, 使得产生的LDPC码的Tanner图最小圈长为8. 由于该类码是准循环码以及其校验矩阵所固有的分层结构, 编码器和解码器都易于实现, 它们分别是线性可编和线性可译的. 所提出的LDPC码码率范围较大, 可以灵活选取. 利用迭代解码进行计算机仿真, 发现新的LDPC码比其他的规则LDPC码在编码OFDM系统中具有更好的性能.     

Faculty and Academic Integrity: The Influence of Current Honor Codes and Past Honor Code Experiences

This survey of faculty at honor code and non-honor code institutions investigated the influence of honor codes on faculty attitudes and behaviors. As hypothesized, we found that honor code faculty have more positive attitudes toward their schools' academic integrity policies and are more willing to allow the system to take care of monitoring and disciplinary activities. Faculty in noncode institutions have less positive attitudes and are more likely to take personal actions designed to both catch and deal with cheaters. We also investigated the potential influence of a student honor code experience on faculty attitudes. We found that, in noncode environments, faculty who had an honor code experience as a student were more likely to believe that students should be held responsible for peer monitoring and to say that they deal personally with cheating. Implications for higher education institutions are discussed.     

企业社会责任的本质、形成条件及表现形式

企业社会责任不是抽象的道德和义务．而是社会环境和企业互动关系客观变化的历史趋势。以往被看作单纯追求利润最大化的企业现在何以自动地通过“生产守则”等形式“承担起”社会责任,其原因应该从企业利益实现机制的客观变化等因素中寻找。本文在此方法基础上定义了企业社会责任的本质。充分发育的市民社会、充分发展的垄断以及共有制的普及是企业社会责任的形成条件,三者关系的不同格局产生企业社会责任的三种表现形式;企业社会责任是历史性的存在,在其发展的第三个阶段将扬弃其自身。这时,企业的边界与社会大众的边界重合或融合,作为外部压力的企业社会责任最终成为企业自身的追求。     

Engineering problem-solving knowledge: the impact of context

Employer complaints of engineering graduate inability to ‘apply knowledge’ suggests a need to interrogate the complex theory-practice relationship in twenty-first century real world contexts. Focussing specifically on the application of mathematics, physics and logic-based disciplinary knowledge, the research examines engineering problem-solving processes as enacted by recent graduates in a range of industrial settings. Theoretically situated in the sociology of education, the Bernsteinian concept of knowledge structures and Legitimation Code Theory epistemic relations are utilised to surface the disciplinary basis of problem solving in different sociotechnical contexts. It is argued that the relationship between the ‘what’ and the ‘how’ of the problem gives rise to significantly different practice ‘codes’ between which successful engineering problem-solvers are required to shift. This paper presents two contrasting case studies which demonstrate the impact of the environment on code-shifting practices. Findings suggest that engineering curricula need to facilitate a more conceptual grasp of contextual complexities.     

ACADEMIC DISHONESTY: A Zero Tolerance Professor and Student Registration Choices

College and university faculty and administrators are responsible for constructing academic honesty policies and communicating them to students. This is often attempted through institutional honesty policies and university-wide honor codes. While these approaches have been widely researched, less attention has been given to the role of individual faculty members. That role is examined in this study by addressing student reactions to professors based on their academic honesty policies. In addition to demographic information, data were gathered about student attitudes and beliefs concerning academic dishonesty and their decision to enroll in or avoid a course being taught by a professor with zero tolerance for academic dishonesty. The findings regarding different instructors’ approaches toward academic dishonesty indicate that an intolerant policy will keep dishonest students away, but at a price—it will also detract many honest students.     

In defence of speech codes

It has been strongly maintained that speech codes at universities interfere with academic freedom, and also, to the contrary, that such speech codes must be developed to restrain appeals to academic freedom that function to restrain the freedom of marginalized groups to participate fully in the university. This essay argues that forms of speech can in fact constrain the freedom, including legitimate academic freedom, of many persons, not only, but importantly including, marginalized groups; that speech codes have always existed; and that reasonable ones can be developed which do not interfere with freedom of teaching, learning, and research in the university; and in particular that definitions of academic freedom such as that developed by the Canadian Association of University Teachers (CAUT) are compatible with such speech codes.     

Codes over Galois rings with respect to the Rosenbloom-Tsfasman metric

We investigate the structure of codes over Galois rings with respect to the Rosenbloom-Tsfasman (shortly RT) metric. We define a standard form generator matrix and show how we can determine the minimum distance of a code by taking advantage of its standard form. We compute the RT-weights of a linear code given with a generator matrix in standard form. We define maximum distance rank (shortly MDR) codes with respect to this metric and give the weights of the codewords of an MDR code. Finally, we give a decoding technique for codes over Galois rings with respect to the RT metric.     

A critical reflection on codes of conduct in vocational education

The contemporary cultural context may be seen as presenting a moral void in vocational education, sanctioning the ascendency of instrumental epistemology and a proliferation of codes of conduct, to which workplace actions are expected to conform. Important among the purposes of such codes is that of encouraging ethical conduct, but, true to their informing instrumental epistemology, they tend to assume that ethical conduct is a formal matter: a priori, extrinsic, deductive, universal, determinate, unproblematic, incontestable, constraining and selfless. However, the context may, conversely, be seen as presenting grounds for a very different view of moral conduct as situated: immanent, intrinsic, cultural, contextualised, underdetermined, problematic, contestable, challenging and authentic. There is suggested, then, a need for vocational educators and trainers to develop the knowledge, capability, commitment and confidence to work as situated moral agents in workplaces of codified expectations to which they may be held accountable.