组态软件中的历史数据处理过程

实时数据库中历史数据是系统定时从实时数据库中采样,保存到历史数据库中的数据,用户需要时可随时从历史数据库中访问历史数据。历史数据库包含内存历史数据库和磁盘历史数据库。内存历史数据库关注的是测点近期数据的组织方式;磁盘历史数据库管理的对象是历史数据文件和管理信息文件。本文描述了磁盘历史数据库的文件结构、缓冲区进行了描述,并阐述了磁盘历史数据库的实现技术。     

基于OCI和ODBC异构数据库通用接口设计

文中分析了ODBC和OCI数据库接口的特点,为解决异构数据库的共享,提出了一种数据库应用程序连接数据库的方法———通用数据库接口。首先明确了通用数据库接口模块在系统中的位置,接着分析了该接口模块具备的具体功能,介绍了模块设计中的三个层次,然后总结了该接口模块的优点。封装了ODBC和OCI的通用数据库接口,可以实现异构数据库的互连,同时可以提高系统的性能。通过数据库调用函数来实现对异构数据库的操作,该通用数据库接口具有通用、简单、可扩展、可优化等特点。     

面向企业网数据库信息的安全技术研究

从数据库信息安全的防护角度对面向企业网络的数据库信息安全展开了分析讨论,简单介绍了常见数据库安全措施和数据库信息安全的关键问题,重点提出了企业网数据库信息的加密改进思想。对数据库加密平台的实现展开了讨论,从加密模型框架和加密字典的设计两个角度完成了面向企业网数据库的信息安全设计。     

面向对象数据库技术及其前景分析

面向对象数据库作为第三代数据库具有前两代数据库无法比拟的优点,满足复杂数据结构和海量存储需要,是新型数据库如多媒体数据库、空间数据库、演绎数据库、工程数据库实现的基础。具体分析了面向对象数据库技术的基本特征、优势、存在的问题,并对面向对象数据库技术未来前景做了预测。     

基于OCI和ODBC异构数据库通用接口设计

文中分析了ODBC和OCI数据库接口的特点．为解决异构数据库的共享，提出了一种数据库应用程序连接数据库的方法——通用数据库接口。首先明确了通用数据库接口模块在系统中的位置，接着分析了该接口模块具备的具体功能，介绍了模块设计中的三个层次，然后总结了该接口模块的优点。封装了0DBC和OCI的通用数据库接口．可以实现异构数据库的互连，同时可以提高系统的性能。通过数据库调用函数来实现对异构数据库的操作，该通用数据库接口具有通用、简单、可扩展、可优化等特点。     

基于SQL Server数据库完整性约束的几点探讨

数据库的完整性约束是设计数据库的核心内容,一个数据库的完整性约束设计的好坏,直接影响到这个数据库的性能,同时也会影响数据库的开发,因此一个好的数据库需要严格考虑其完整性约束。本文对SQL Server 2000数据库中的完整性约束进行了探讨,并用T-SQL语句对数据库完整性约束进行了设计,从而实现了在数据库中存储数据的完整性、正确性和一致性。     

连接池提高数据库访问效率的测试

传统的数据库连接方式,已经成为了程序运行效率的瓶颈,频繁的建立和释放连接会降低数据访问的效率,增加系统的负担。对数据库连接缺乏管理会影响整个系统的性能。解决的方法是采用数据库连接池来管理数据库连接。本文通过一个具体的测试案例来分析使用了数据库连接池的系统和未使用数据库连接池的系统在,数据库访问效率上的差别。并探讨了数据库连接池的优势以及对本案例中数据库连接池的优化。     

关于Access数据库安全性研究

数据库安全性问题是一直是围绕着数据库管理的重要问题,数据库数据的丢失以及数据库被非法用户的侵入使得数据库安全性的研究尤为重要。本文以比较常用的Access数据库为例围绕数据库的安全性技术作了分析,并介绍了数据库安全策略。     

ADO数据库访问技术在脚本语言中的应用

介绍了ADO数据库技术的原理,对在不同数据库、不同脚本语言下利用ADO数据库技术访问数据库进行了探讨。     

Delphi应用程序中如何使用事务进行数据更新

数据库事务处理是数据库应用开发中的常见问题。了解和掌握数据库事务对于数据库应用系统设计者来说相当重要。本文首先数据库事务做了简单描述,并详细介绍了Delphi中用于实现数据库事务的TDataBase构件的重要属性和方法。     

Information technology in the National Curriculum: a view from Scotland

Abstract This paper examines the proposals for Information Technology (IT) in current curriculum developments in England and Wales and in Scotland. It points out significant differences between the pattern of curriculum developments in these two parts of the United Kingdom, noting in particular, that developments under the heading of The National Curriculum do not apply in Scotland. Nevertheless, IT developments in Scotland have many similarities to those in the rest of the UK and it is from this shared experience that a view is offered as to whether the proposals under The National Curriculum will allow IT to reach its full potential to shape the curriculum and to improve learning and teaching styles. Among the issues considered are the interplay between IT and the curriculum, the impact of IT on learning and teaching and the fundamental question as to whether the system—pupils, teachers, staff management and staff development arrangements—are likely to be able to respond to the National Curriculum proposals.     

Affinity-Based Network Interfaces for Efficient Communication on Multicore Architectures

Improving the network interface performance is needed by the demand of applications with high communication requirements (for example, some multimedia, real-time, and high-performance computing applications), and the availability of network links providing multiple gigabits per second bandwidths that could require many processor cycles for communication tasks. Multicore architectures, the current trend in the microprocessor development to cope with the difficulties to further increase clock frequencies and microarchitecture efficiencies, provide new opportunities to exploit the parallelism available in the nodes for designing efficient communication architectures. Nevertheless, although present OS network stacks include multiple threads that make it possible to execute network tasks concurrently in the kernel, the implementations of packet-based or connection-based parallelism are not trivial as they have to take into account issues related with the cost of synchronization in the access to shared resources and the efficient use of caches. Therefore, a common trend in many recent researches on this topic is to assign network interrupts and the corresponding protocol and network application processing to the same core, as with this affinity scheduling it would be possible to reduce the contention for shared resources and the cache misses. In this paper we propose and analyze several configurations to distribute the network interface among the different cores available in the server. These alternatives have been devised according to the affinity of the corresponding communication tasks with the location (proximity to the memories where the different data structures are stored) and characteristics of the processing core. As this approach uses several cores to accelerate the communication path of a given connection, it can be seen as complementary to those that consider several cores to simultaneously process packets belonging to either the same or different connections. Message passing interface (MPI) workloads and dynamic web servers have been considered as applications to evaluate and compare the communication performance of these alternatives. In our experiments, performed by full-system simulation, improvements of up to 35% in the throughput and up to 23% in the latency have been observed in MPI workloads, and up to 100% in the throughput, up to 500% in the response time, and up to 82% in the requests attended per second have been measured in dynamic web servers.     

Spatio-temporal distribution of rice phenology and cropping systems in the Mekong Delta with special reference to the seasonal water flow of the Mekong and Bassac rivers

Multi-temporal Moderate Resolution Imaging Spectroradiometer (MODIS) data was used to estimate the spatial distribution of heading date and rice-cropping system employed in the Mekong Delta relative to seasonal changes in water resources in 2002 and 2003. We improved a Wavelet-based Filter for determining Crop Phenology (WFCP) and developed a Wavelet-based Filter for evaluating the spatial distribution of Cropping Systems (WFCS) to the interpretation of MODIS time-series data to determine the spatial distribution of rice phenology and various rice-cropping systems from the seasonal Enhanced Vegetation Index (EVI) data. The findings correspond well the physical characteristics of the cropping system in the Mekong Delta, which have changed over time in response to localized and seasonal changes in water resources. One such example is the double-irrigated rice-cropping system commonly employed in the upper Mekong Delta in the dry season to avoid damage due to the subsequent floods. The shortage of suitable irrigation water and intrusion of saline water in the coastal regions during the dry season has constrained the practice dry-season cropping and has meant that the double- and single-rainfed rice-cropping systems are employed in the rainy season. A triple-irrigated rice-cropping system is used in the central part of the Mekong Delta which is located midway between the flood-prone and salinity intrusion areas. Analysis of annual changes in the rice cropping systems between 2002 and 2003 showed that the triple-cropped rice expanded to the flood- and salinity-intrusion areas. This expansion indicates that the implementation of measures to limit the extent of flooding and salinity intrusion by improved farming technologies and improvements in land management. The heading dates in the upper Mekong Delta in 2003 were earlier than in 2002 by approximately 20 to 30 days. The reasons for this would be due to decreased flood runoff in 2002 compared to 2001, and implementation of government policies regarding early sowing of dry-season crops. Subsequent analysis of the MODIS data confirmed that the spatial distribution of rice-cropping systems was closely related to seasonal changes in river runoff regime in the Mekong Delta.     

Ergonomics evaluation of modified industrial helmets for use in tropical environments

Hotness, weight, fitting problems etc., have been found to be the chief causes of the unpopularity of industrial safety helmets in tropical environments in developing countries (DC). Some selected safety helmets manufactured in industrialized countries (IC) were modified to provide extra head ventilation and to reduce weight, in order to make them more acceptable to users in hot environments. The modified helmets were subjected to ergonomics evaluation both objectively and subjectively in the laboratory (in simulated tropical conditions) as well as in the field situation. There was evidence that white helmets had some advantages in comfort, viz. reduction of hotness, compared to the other colours, e.g. red, green etc., when worn in the presence of radiant heat in the laboratory. Ventilation holes provided at the top of the shell seemed to reduce the greenhouse effect within the helmet shell which therefore felt less uncomfortable than a fully covered helmet. Even with a small reduction of weight, such as 45 g in helmets weighing about 350g, the difference in weight was perceived by the wearers. In adapting helmets made in IC for use in tropical climates, head ventilation and low weight perception are important aspects in comfort which need to be considered. In addition to low cost, a harness material suitable for sweat absorption is required. Adjustability and sizing to fit 90% of the user population also needs to be considered in the design and manufacture of safety helmets for people in DC.     

Evolvable work-centred support systems for command and control: creating systems users can adapt to meet changing demands

Military command and control (C2) organizations are complex socio-technical systems which must constantly adapt to meet changing operational requirements. We describe our experiences in developing a work-centred support system (WCSS) to aid weather forecasting and monitoring in a military airlift C2 organization as an illustrative case. As part of the development process we conducted field observations both before and after introduction of the WCSS in their operations centre. A striking finding was the constant changes that operations personnel faced (changes in goals and priorities, changes in scale of operations, changes in team roles and structure, and changes in information sources and systems). We describe the changes in workplace demands that we observed and the modifications we needed to make to the WCSS in response. For today's fielded systems, it is seldom possible to make changes that are responsive to users' changing requirements in a timely manner. We argue for the need to incorporate facilities that enable users to adapt their systems to the changing requirements of work and point to some promising directions towards evolvable work-centred support systems.     

Promotion and prevention orientations in the choice to attend lectures or watch them online

When presented with the option to use a new instructional technology, students often face an approach–avoidance conflict. This study explored promotion and prevention orientations, concepts linked to approach and avoidance in Higgins's regulatory focus theory, in the choice to attend lectures or watch them online. Openness, a core disposition in the Big Five Model of personality, and positive attitudes towards the utility of the Internet, reflect promotion orientations that are potentially related to the choice to watch lectures online. By contrast, neuroticism, another core disposition in the Big Five Model, and anxiety about the Internet as a computer technology, reflect a prevention orientation that is potentially related to the choice of attending lectures in class. The results illustrate that both promotion and prevention are at work in the choice to attend lectures or to watch them online. Neuroticism and anxiety about the Internet as a computer technology were related to the choice to attend lectures in class, whereas the perceived utility of the Internet was related to the choice to watch lectures online. Instructional mode choice was not related to examination performance, suggesting that the choice to attend lectures or watch them online has more to do with individual differences in promotion and prevention orientations than with pedagogical characteristics that impact learning.     

From Dewey to Gates: A model to integrate psychoeducational principles in the selection and use of instructional technology

The purpose of this article is to propose a model to integrate educational mastery principles that emphasize cooperative and learner-centered instruction in higher education with the new advances of instructional technology, and to present a pilot case study to exemplify the model. It is clear that in spite of tremendous efforts by colleges and universities to introduce instructional technology in the classroom, many faculty remain skeptical of the new technologies. It is suggested that in order for instructional technology to be widely accepted and used by faculty, the value of this technology to improve classroom instruction has to be proven. It is proposed that this can be achieved by applying learner-centered principles, in which the instructional objectives of the class are directly linked both to the needs of the student and the role of the instructor in the classroom, which in turn determine the appropriate type and use of instructional technology. It presents a pilot case study in which a technology was used to teach a basic psychology concept.     

Theory and practice of protection of personal names in the domain space or “renewed” cybersquatting (in terms of the states of Eastern Europe)

With the development of the Internet, more people are creating personal websites and blogs, and they expect to be able to use their own name or surname in the domain name. The aim of this article is to identify and analyse the existing problems in the use and protection of personal names in the domain space, as well as the development of legal approaches that can be used to resolve disputes that arise. In the course of the analysis, the authors conclude that the existing legal regulations at both the international and national levels are not sufficient to protect personal names effectively. Current approaches in this area are scattered and not systematic. The conclusions and suggestions made in this paper can be used to form a specialised procedure to resolve domain name disputes relating to personal names, as well as in the course of organising and updating the national legislations of the states of Eastern Europe.     

从政策研究视角看大数据对科研管理与决策的影响

在大数据时代,数据已成为重要的战略性资源,正在对社会管理的各项决策产生越来越重要的影响。本文从政策研究角度分析了在科研管理领域运用大数据辅助科研管理及其决策,并以中科院管理信息化发展为例讨论了运用大数据的可行性;提出在科研管理领域应当重视对大数据价值的深入分析与挖掘,推动科研管理与决策机制从业务驱动向数据驱动转变,从精细化的单项管理走向趋势化的复合管理;应当围绕科技创新在国家发展全局的核心位置,加强顶层战略部署,政策引导,有序推进,发挥大数据关联共享、智慧决策的优势,推进大数据时代的科研管理与决策支持环境建设。     

基于光网络SDH的施工和维护工作探讨

在光网络SDH施工和维护要做好事前预防,对维护和施工中发现的问题要做及时处理,把存在的问题消灭在萌芽状态。确保SDH设备及系统处于良好的运行状态。文中就SDH设备及系统在维护和施工中对应该注意的问题和内容进行了分析和探讨。可作为光网络SDH设备施工和维护人员参考。