From Language Concepts to Implementation Concepts

We outline some of the impact of Christopher Strachey, particularly by referring to work on program equivalence and implementation correctness for programming languages.     

Christopher Strachey, 1916-1975: A Biographical Note

Christopher Strachey was one of the most original computer scientists of his generation: his fields were computer design and programming, and he made important contributions to them both. He liked to say (not quite accurately) that he had changed the direction of his career every seven years. The different phases of his life and career are reflected in the five sections of this note.     

Continuations Revisited

To introduce the republication of his joint 1974 paper with Christopher Strachey, Continuations: A Mathematical Semantics for Handling Full Jumps, the author recalls earlier unsuccessful struggles which culminated eventually in the almost instantaneous insight for their discovery of continuations in 1970.     

Locations considered unnecessary

Summary Recent papers have attacked the use of locations, or pointers, as data objects in programs. This paper considers a generalization of this attack — attempting to remove locations from the underlying semantic model. Using the mathematical semantics of Scott and Strachey, we show that reference parameters and Algol scope rules for procedures, two constructs requiring the notion of reference, can be replaced with alternative constructs not requiring locations in the definition. Some conclusions are also drawn about the use of mathematical semantics as a language design tool.This research was partially supported by the National Research Council of Canada and by National Science Foundation grant MCS 76-14293     

From Macrogeneration to Syntactic Abstraction

In his 1967 lecture notes, Christopher Strachey states that macrogenerators are useful as the only alternative to rewriting the compiler when language extensions are needed. He also states, however, that they deal inappropriately with programs as strings of symbols, ignoring their semantic content, and that they lead to inconvenient syntax and often less transparent code. He concludes that a goal of language designers should be to eliminate the need for macrogeneration. This article attempts to reconcile the contemporary view of syntactic abstraction, which deals with programs at a higher level, with Strachey's views on macrogeneration.Syntactic abstraction has evolved to address the deficiencies of macrogeneration and has, to a large extent, eliminated them. Syntactic abstractions are conveniently expressed, conveniently used, and usually lead to more rather than less transparent code. While a worthwhile goal for language designers is to reduce the need for macrogeneration through the inclusion of an appropriate set of built-in syntactic forms, this article concludes that syntactic abstraction is a valuable tool for programmers to define language extensions that are not anticipated by the language designer or are domain-specific and therefore not of sufficiently general use to be included in the language core.     

Modular verification of Ada generics

This paper develops modular verification rules for Ada generics which are proven to be sound and complete. The generic mechanism in Ada allows modules to be parameterized by types, procedures and functions. The modularity property allows a generic to be verified once, and then exported to other modules which assume that it is correct. This requires the generic to have a specification which is used in verifying other modules, but its implementation cannot be used for this purpose. Thus, modular verification cannot be based on removing generics by macro expansion which requires the use of the generic's implementation. The main difficulty with specifying and verifying a generic is that the specification language may need to be extended with a new theory for specifying and reasoning about properties of objects whose type is a parameter to the generic. Such theories must be part of the specification of the generic, and this raises the possibility that the extended specification language may not be expressive, even if it was before the extension. The use of strings in our specification language prevents this from happening, which is proven in the paper; this is a major step toward establishing the completeness of our rules. Modularity also had a large impact on our semantics for programming constructs which is quite different from the usual semantics in the literature, even though it is still based the denotational semantics of Scott and Strachey. The main reason for this is that we had to modify the standard definition of validity. Modularity requires that validity depend on certain internal assertions in a program, such as the precondition of a procedure invoked in the program.     

用计量风格学方法考察《水浒传》的作者争议问题——以罗贯中《平妖传》为参照

《水浒传》是独著还是合著、施耐庵和罗贯中是何关系一直存在争议。该文将其作者争议粗略归纳为施耐庵作、罗贯中作、施作罗续、罗作他续、施作罗改五种情况,以罗贯中的《平妖传》为参照,用假设检验、文本聚类、文本分类、波动风格计量等方法,结合对文本内容的分析,考察《水浒传》的写作风格,试图为其作者身份认定提供参考。结果显示,只有罗作他续的可能性大,即前70回为罗贯中所作,后由他人续写,其他四种情况可能性都较小。     

Insights into ICT capability on a teacher-mentored PGCE course

The study examines the development of ICT capability by associate-trainees on a postgraduate certificate of education course. The course involves the promotion of ICT use during three classroom placements by in-school teacher-mentors. Data for the study were collected by a survey of mentors, four surveys of associate-trainees, and by the collation of associate-trainees' profiles. The study considers the perceived effects upon the trainees development of ICT capability by the course generally and the examples of ICT use provided by teacher-mentors in particular. The study indicates the beneficial effects upon the attitudes of trainees who observe ICT use by teacher-mentors on early school placements, and the coincidence of impoverished ICT use by teacher-mentors on early school placements with restricted use of ICT by associate-trainees on later placements.     

微信接警系统

本文提出了微信报警、省上统一接警与三台合一系统联动处警的综合解决方案, 并进行了系统模型研究及可行性实现验证. 微信报警与接警主要是借助微信APP公众号服务, 基于微信开放平台和移动网络通信技术实现, 而联动处警依靠消息推送并以事件触发方式实现. 微信报警简单易用, 易于被多数人接受, 是有效的报警方式.     

液晶显示器斑痕缺陷高质量背景建模

针对目前液晶显示器斑痕(LCD-Mura)缺陷背景抑制检测中重建的背景存在引入性噪声干扰和目标缺损的问题,提出一种基于奇异值分解(SVD)和最大熵的缺陷图像背景建模方法:通过SVD图像像素矩阵,求得奇异值序列;借助矩阵范式推导出图像分量与奇异值的对应关系,进而以图像各分量奇异值所占比率计算各分量的熵值,以此利用最大熵确定重建背景的有效奇异值;再由矩阵重构得到背景,并进一步提出关于背景重建效果评价的一般方法。相比双三次B样条曲线拟合方法,该方法将区域Mura的对比度最少提升0.59倍,提升线Mura对比度最多达到7.71倍;相比离散余弦变换(DCT)方法,该方法将点Mura的噪声最少降低33.8%,将线Mura噪声降低76.76%。仿真结果表明,该模型具有低噪、低损和高亮的优点,能够更为准确地构建出缺陷图像的背景信息。     

Learning by *ing的教学模式与实践

本文论述了Learning by Doing,Learning by Abstracting,Learning by Analogy,Learning byTeaching以及Learing by Simulating等教学模式。分析了其优点,并介绍了我们将其应用于嵌入式软件开发导论和系统结构等课程的效果。文中尤其强调了Learning by Abstracting的重要性。     

Measuring by judgement

Measurement in many industrial and practical contexts is done by human judgement. These judgements group the possible measures into about seven categories, such as large, medium and small in relation to the expected average and range of the values. The number of categories used in judgement can be increased by allowing more time for judgement, by using multi-dimensional representations, by giving knowledge of results, and by providing a constant comparison value. The discriminating accuracy of judgement can be improved by reducing the range of values to be judged. The use of these judgements in scale reading and personal ratings is discussed.     

面向对象的城市建筑物点云数据加载和组织

采用面向对象程序设计方法对三维点云数据进行分析,研究以Visual C++6.0为开发平台利用图像法对激光扫描获取的城市建筑物点云数据进行组织的计算机实现方法。通过扫描关系确定点云数据中有效目标点的全局唯一索引值,将点云数据看作一幅深度图像,确定全局索引值对应的图像行列值,再利用该行列值计算每个点对应的法向量,分类和组织点云数据。实验结果表明,利用面向对象的图像处理技术可以方便、快捷地实现三维点云数据的加载和组织。     

An entropic criterion for minimum uncertainty sensing inrecognition and localization. I. Theoretical and conceptual aspects

A criterion is presented for the automatic selection of a sensor measurement aimed at observing the state of a system which is described both by discrete variables and by continuous ones. The criterion is based on the expected value of the entropy variation associated to the sensor observation. This criterion is then applied to object recognition and localization tasks, in which the observed system is characterized by the object class, represented by a discrete variable, and by the object pose, i.e., position and orientation, represented by a vector of continuous parameters. The proposed criterion also accounts for the information obtained in the case the observed object is missed by the measurement.     

基于复合幂函数修正G1法的商户综合评价

针对多指标综合评价问题中主客观权重相悖时客观权重淹没主观权重的问题,以G1法和客观赋权法为基础,提出了复合幂函数修正G1法的组合赋权模型。首先,建立指标体系并通过G1法确定各指标主观排序和主观初始向量;然后,利用客观赋权法计算各指标客观向量;其次,在不改变主观排序的情况下利用复合幂函数算出主客观结合的综合权重;最后,利用各指标标准化后的值和综合权重计算综合评价值。采用大众点评网的商户数据进行综合评价实验：该模型的均方根误差（RMSE）为3.891,均低于G1-熵权法的8.818和标准差修正G1法的4.752,且覆盖率优于两种对比方法;分别修改主观初始向量和主观排序进行对比实验,修改主观排序的均方根误差为5.430,高于修改主观初始向量的1.17。实验结果表明,该模型得到的评价值与大众点评网官方的评分的一致性较高,且该模型弱化了主观初值对评分结果的影响,体现了主观排序的基础作用。     

Study of Ardmore,Oklahoma, storm clouds. I. Convective storm cloud initiation and development based on the remote sensing gravity-wave-induced convection

Abstract

Convective instability can be induced by unstable vertical temperature profiles and can be supported by the release of latent heat of water vapour provided by a large quantity of moisture in the air. It can also be released by the presence of gravity waves. Large amplitude gravity waves have been linked to the onset of convective storm systems. In this study, the vertical velocity of convection initiated by gravity waves was investigated. The study of Ardmore, Oklahoma, storms showed that weak convection was initiated by gravity waves having wave periods of 35 min and the convection was enhanced by gravity waves having wave periods of 20 min. Evidence for cloud formation, due to the condensation of water vapour through convection initiated by the gravity waves, was obtained from rapid-scan satellite imagery and radar summaries. In this particular case, the convective motion, initiated and supported by the gravity-wave-induced activity (excluding contributions made by other mechanisms), reached its maximum value about one hour before the production of the funnel clouds. In this study, we did not rule out the contributions made by other mechanisms, such as low-level convergence and others, toward the initiation of convection; however, our main purpose is to discuss the role of gravity waves in wave-induced convection contributing to the fractions of formation and development of severe convective storms.     

基于多信道Ad Hoc网络的WDSCN的设计

介绍一种基于多信道Ad Hoc网络的思想来实现无线分布式传感/控制网络(WDSCN)。网络节点硬件主要使用UBICOM公司的IP2022作为MCU、Nordic公司的nRF905作为射频芯片。软件以C语言和汇编语言编制,采用多层次结构设计。由于采用多信道的具有自动跳频功能的Ad Hoc网络,该WDSCN具有较强的抗干扰能力,具有较高的实用价值。     

低成本拍摄式微课的开发与应用研究

本文对低成本拍摄式微课的开发与应用现状进行研究。借鉴胡铁生总结的“微课开发流程”,以教学设计理论和教育电视编导与制作理论为指导,设计了低成本拍摄式微课的开发策略：选择主题—教学设计—录制准备—现场录制—后期编辑—评价反馈。通过实践验证了应用该策略制作的微课开展教学能提高学生的学习效果和学习质量。