基于Blackboard平台的北大教学网在不同规模课程中的应用与实践

本文以两门不同规模、不同定位的课程为例,总结在使用北大教学网过程中的体会,归纳利于学生自主学习的混合式教学方法,并对信息化环境下如何提高教学效果与学习效率提出了一些探讨性的建议。     

用8031，DRAM和高速A/D实现快速数据采集

介绍了一个用８０３１，ＤＲＡＭ和高速Ａ／Ｄ等芯片构成的快速数据采集系统。该系统使Ａ／Ｄ转换的数据不经ＣＰＵ“中转”，而直接存入ＤＲＡＭ中。它具有硬件结构简单、价格低廉、易实现大容量存储等优点。本系统对模拟信号的采集并将采集数据送入存储器的周期为８μｓ。     

A camera-joystick for sound-augmented non-visual navigation and target acquisition: a case study

This paper presents the results of a comparative study of user input with a camera-joystick and a manual joystick used in a target acquisition task when neither targets nor pointer could be perceived visually. The camera-joystick is an input technique in which each on-screen item is accessible from the center with a predefined vector of head motion. Absolute pointing was implemented with an acceleration factor of 1.7 and a moving average on 5 detected head positions. The underlying assumption was that, in order to provide a robust input for blind users, the interaction technique has to be based on perceptually well-discriminated human movements, which compose a basic framework of an accessible virtual workspace demanding minimum external auxiliary cues. The target spots, having a diameter of 35 mm and a distance between the centers of adjacent spots of 60 mm, were arranged in a rectangular grid of 5 rows by 5 columns. The targets were captured from a distance of 600 mm. The results have shown that the camera input is a promising technique for non-visual human–computer interaction. The subjects demonstrated, more than twice, better performance in the target acquisition task with the camera-joystick versus the manual joystick. All the participants reported that the camera-joystick was a robust and preferable input technique when visual information was not available. Blind interaction techniques could be significantly further improved allowing a user-dependent activation of the navigational cues to better coordinate feedbacks with exploratory behavior.     

海上多波勘探装备关键技术的突破

海上多波勘探仪器是当今海上地震勘探技术缺点，文中介绍了海底电缆的功能、原理及国产样机的设计和在关键技术民的突破，并通过与国外几家大现类产品的对比，展示 阵产海上多波勘探仪器所具的优势及今后的推广前景。     

嵌入式脉象采集仪电路设计

该脉象采集仪采用IP核技术、SoPC技术，将脉象采集的大部分功能都集成在一片FPGA内部，并自主进行了脉象采集控制的FPGA设计。该设计采用在SoPC系统外做控制电路部分，三路脉搏信号共用一个ADC，只需要很少的外部器件就能实现。与早期采用工控机、PC机，或者现在多采用的ARM设计方法相比，该脉象采集仪具有成本低，功耗低，体积小，便于扩展，稳定性高和系统维护方便等优点。     

Cognitive skill acquisition and transfer in younger and older adults.

The acquisition of cognitive skills often depends on 1 of (or a combination of) 2 processes, the execution of an algorithm, and the retrieval of problem instances. This study examined the effects of age and repetition of problem instances on the production and verification of solutions to 2 serially presented sets of alphabet arithmetic problems. Analyses of the parameters derived from power-function fits for individuals revealed age differences favoring young adults in improvement span, learning rate, and asymptote. For both age groups, the beneficial effects of repetitions on 1st-set response times were attributable to algorithmic speedup and to the retrieval of instances, whereas improvements in the speed of 2nd-set response times were attributable primarily to item retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transaction attributes and buyer-supplier relationships in AMT acquisition and implementation: the case of Malaysia

This paper explores how transaction attributes of technology affect differences in the relationship between technology buyers and suppliers. It also examines the impact on performance of different patterns of relationship between technology buyers and suppliers. Data obtained from 147 manufacturing firms in Malaysia are used to test several hypotheses, which were derived from a review of the literature on technology, transaction cost theory and buyer–supplier relationships (BSR). The research results indicate that the higher the level of technological complexity, specificity and uncertainty, the more firms are likely to engage in a closer relationship with technology suppliers. Even though the majority of firms reported improvements in their performance, results indicate that firms demonstrating a closer relationship with technology suppliers are more likely to achieve higher levels of performance than those that do not. It is also shown that with high levels of transaction attribute, implementation performance suffers more when firms have weak relationships with technology suppliers than with moderate and low levels of transaction attribute.     

基于单片机与VC＋＋的生物荧光信号采集系统

介绍一种建立在单片机系统以及VC＋＋的荧光信号采集系统设计。该硬件系统采用8051芯片采集控制,用MAX187作为A/D转换的芯片,用MAX232串口实现通信,用PC上的Visual C＋＋作为开发工具。该系统是用于荧光光谱的检测。     

Knowledge acquisition by incremental learning from problem-solution pairs

This paper describes LEW (learning by watching), an implementation of a novel learning technique, and discusses its application to the learning of plans. LEW is a domain-independent learning system with user-limited autonomy that is designed to provide robust performance in realistic knowledge acquisition tasks in a variety of domains. It partly automates the knowledge acquisition process for different knowledge types, such as concepts, rules, and plans. The inputs to the system, which we call cues , consist of an environmental component and of pairs containing a problem and its solution. Unlike traditional forms of "learning from examples", in which the system uses the teacher's answer to improve the result of a prior generalization of an example, LEW treats the problem-solution or question-answer instances, i. e., the cues themselves, as the basic units for generalization.     

马厂油田高密度三维观测系统设计研究

马厂油田的地下地质构造复杂，以往采集的地震资料无法满足当前勘探开发的需要。针对这一问题，开展了高密度三维采集观测系统设计研究。基于马厂构造的地质构造特点，对观测系统的各类参数进行了分析试验，在此基础上设计了小道距、小炮点距、小接收线距和小激发线距的观测系统，并根据目标区实际地质构造特点，采用可变面元方式进行数据采集。高密度观测系统的特点是物理点密度较大，覆盖次数高，炮检距分布均匀。正演模拟和实际应用表明，采用高密度三维采集观测系统采集的资料，信噪比和分辨率较老资料有显著提高，特别是中、深层资料的信噪比得到了明显改善。