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关键词： Program comprehension   Software quality   Quality assessment  

摘要： Readers of programs have two main sources of domain information: identifier names and comments. When functions are uncommented, as many are, comprehension is almost exclusively dependent on the identifier names. Assuming that writers of programs want to create quality identifiers (e.g., identifiers that include relevant domain knowledge), one must ask how should they go about it. For example, do the initials of a concept name provide enough information to represent the concept? If not, and a longer identifier is needed, is an abbreviation satisfactory or does the concept need to be captured in an identifier that includes full words? What is the effect of longer identifiers on limited short term memory capacity? Results from a study designed to investigate these questions are reported. The study involved over 100 programmers who were asked to describe 12 different functions and then recall identifiers that appeared in each function. The functions used three different levels of identifiers: single letters, abbreviations, and full words. Responses allow the extent of comprehension associated with the different levels to be studied along with their impact on memory. The functions used in the study include standard computer science textbook algorithms and functions extracted from production code. The results show that full-word identifiers lead to the best comprehension;however, in many cases, there is no statistical difference between using full words and abbreviations. When considered in the light of limited human short-term memory, well-chosen abbreviations may be preferable in some situations since identifiers with fewer syllables are easier to remember.

关键词： 除法运算   求余运算   赋值运算   自增   自减运算   逗号运算   逻辑运算  

摘要： C语言提供了非常丰富的运算符,这些看似简单的运算符之间,有着特殊的规则。本文就学习C语言运算时,容易造成学生困惑的几种运算符,采用详尽的C语言实例论证,使学生能够较好地理解C语言运算。

关键词： 5-azacytidine   CpG   DNA methylation   identifier element   pyrosequencing  

摘要： A large portion of the genome represents repetitive elements. Identifier (ID) elements, the major elements of short interspersed repetitive elements, are widespread with about 150 000 copies in the rat genome. Each I D element contains six CpG dinucleotides, which might account for the global methylation status of rat. We validated the CpG methylation of the ID elements by various methods. The methylation of one CpG site (CpG-3) of the ID element was investigated by performing pyrosequencing. The methylation percentage of the CpG-3 site was 53.6% (SD = 2.2) on average from six rat tissues with blood, but 24.6% (SD = 1.0) in rat pheochromocytoma, PC-12, cell line. This CpG-3 methylation was further verified by whole genome amplification (WGA), 5-azacytidine treatment, and proportional mixing of rat WGA genomic DNA (gDNA) with liver gDNA. Methylation-sensitive restriction enzyme PCR method showed that three other CpG sites (CpG-1, CpG-4, and CpG-5) within the ID element were also methylated (about 60%) in rat gDNA, but not in WGA gDNA. The ID elements may be good candidates for routine analysis of the global DNA methylation changes of rat for pharmaceutical treatment and their use can make basic epigenetic research possible with high accuracy.

关键词： ALGORITHMS   NUMERICAL range   LINEAR operators   VARIABLES (Mathematics)   MATHEMATICAL constants   DIFFERENTIAL equations  

摘要： The article implements the algorithm of numerous methods for the synthesis of control system which is based on the assumption of exact knowledge of the state vector x(t). Topical is the problem of exact or at least approximate reconstruction of the vector x(t) on the basis of known values of output variables. Moreover, one solution method is to use an observer or identifier, a dynamical system whose solutions infinitely approach the process x(t).

关键词： Source Database   Proprietary Database   Protein Identifier   DBCP   Rest Interface  

摘要： Background: Each major protein database uses its own conventions when assigning protein identifiers. Resolving the various, potentially unstable, identifiers that refer to identical proteins is a major challenge. This is a common problem when attempting to unify datasets that have been annotated with proteins from multiple data sources or querying data providers with one flavour of protein identifiers when the source database uses another. Partial solutions for protein identifier mapping exist but they are limited to specific species or techniques and to a very small number of databases. As a result, we have not found a solution that is generic enough and broad enough in mapping scope to suit our needs. Results: We have created the Protein Identifier Cross- Reference ( PICR) service, a web application that provides interactive and programmatic ( SOAP and REST) access to a mapping algorithm that uses the UniProt Archive ( UniParc) as a data warehouse to offer protein cross- references based on 100% sequence identity to proteins from over 70 distinct source databases loaded into UniParc. Mappings can be limited by source database, taxonomic ID and activity status in the source database. Users can copy/ paste or upload files containing protein identifiers or sequences in FASTA format to obtain mappings using the interactive interface. Search results can be viewed in simple or detailed HTML tables or downloaded as comma- separated values ( CSV) or Microsoft Excel ( XLS) files suitable for use in a local database or a spreadsheet. Alternatively, a SOAP interface is available to integrate PICR functionality in other applications, as is a lightweight REST interface. Conclusion: We offer a publicly available service that can interactively map protein identifiers and protein sequences to the majority of commonly used protein databases. Programmatic access is available through a standards- compliant SOAP interface or a lightweight REST interface. The PICR interface, documenta

关键词： ENGINEERING   ALGORITHMS   MATHEMATICAL analysis   STUDY & teaching   TRANSFORMATIONS (Mathematics)   NUMERICAL analysis  

摘要： To enhance system robustness between system parameters and adaptation law, a supervised adaptive PID control scheme and time-varying fuzzy identifier of unknown nonlinear dither systems are proposed. The dither and the proposed time-varying term can obtain the smooth quality of plant for reducing the rule number of the fuzzy identifier. The supervised adaptive PID control law aims to pull the states back to the pre-specified state region and reduce overshoot towards an extra stabilising input.

关键词： P2P   Web服务   标识符  

摘要： 针对Web服务的瓶颈性缺陷,提出了基于P2P的Web服务,介绍了在P2P模式下服务发布、服务发现、加入节点、删除节点的方案并将基于P2P的Web服务与传统的Web服务做了比较。在基于P2P的Web服务体系结构中,所有节点都是对等的,有效地解决了中央服务器阻塞问题。

关键词： autonomous mobile robots   system identification   polynomials  

摘要： Developing robust and reliable control code for autonomous mobile robots is difficult, because the interaction between a physical robot and the environment is highly complex, subject to noise and variation, and therefore partly unpredictable. This means that to date it is not possible to predict robot behaviour based on theoretical models. Instead, current methods to develop robot control code still require a substantial trial-and-error component to the software design process. This paper proposes a method of dealing with these issues by (a) establishing task-achieving sensor-motor couplings through robot training, and (b) representing these couplings through transparent mathematical functions that can be used to form hypotheses and theoretical analyses of robot behaviour. We demonstrate the viability of this approach by teaching a mobile robot to track a moving football and subsequently modelling this task using the NARMAX system identification technique. (c) 2007 Elsevier B.V. All rights reserved.

关键词： AIDC   自动识别和数据捕捉   空白格式   数据采集   格式(纸)   高频   识别   信息技术   标志   性能   射频识别   规格试验   额定值   RFID   规范(验收)   标识符   技术数据单   试验设备   测试   测试条件  

标准号: ISO/IEC 18046-3-2007

摘要： This part of ISO/IEC 18046 defines test methods for performance characteristics of radio frequencyidentification (RFID) tags for item management, and specifies the general requirements and test requirementsfor tags which are applicable to the selection of the devices for an application. The summary of the test reportsform a unified tag datasheet. It does not apply to testing in relation to regulatory or similar requirements.

关键词： 网络   异常检测   TCP   标识符  

摘要： 将TCP标识符引入到异常检测研究中,提出了一种能实时检测网络异常的入侵检测方法。利用对Tcpdump所获得的数据进行在线检测,快速高效的检测出网络中所出现的异常,减少了普通入侵检测中的漏报率和误报率。该方法可以快速应用于高速网络中,实时检测出网络中的异常,具有一定的自适应性。