ADC系统性能测试及提高

本文简介了一种基于FPGA和DSP,对ADC系统进行性能分析并对其转换后的数字进行数据采集的方法。其中性能分析主要是针对ADC的信噪比和无杂散动态范围。同时,主要介绍了ADC系统中时钟、电源、模拟信号输入等方面性能改善的方法。并以此来提高SNR,实现对有效位数和整体性能的提高。     

基于UC-7420的电能量管理终端的设计与实现

在智能电网的建设中,电能量管理系统是必备的系统,电能量管理终端又是此系统的重要组成部分。本文介绍一种基于MOXA公司的UC-7420平台的电能量管理终端,UC-7420的CPU是精简指令集IntelXscale架构的IXP422处理器,预装了嵌入式Linux操作系统。用户软件采用模块化设计,各个模块由单独的线程实现,整体采用多线程技术。终端可以启用多个抄表线程,极大地提高了抄表的效率和电力数据的实时性;添加了shell脚本,提高了终端的稳定性和可靠性。     

一种双向元数据管理系统

作为企业级数据仓库的路径图,元数据在企业级数据仓库的建设中起着重要的作用。设计一个描述能力强、内容完善的元数据,是有效实现企业级数据仓库功能的重要环节。该文通过对双向体系元数据管理系统的研究,给出了一个企业级数据仓库的元数据管理的解决方案。该方案能够支持从企业级数据仓库子系统抽取元数据存储到元数据管理系统,同时也支持向数据仓库子系统提供其所需的元数据信息,解决诸多企业级数据仓库的运行管理问题,大大减少了企业级数据仓库的管理难度、保证了元数据的准确性、使得各子系统能高效地通信和稳定运行。     

Nonlinear L2-by-3 transform for PAPR reduction in OFDM systems

Orthogonal frequency division multiplexing (OFDM), the multicarrier modulation technique with high bandwidth efficiency and robustness against multipath fading, is used in several high-speed broadband communication systems including digital video broadcasting (DVB), digital audio broadcasting (DAB), asymmetric digital subscriber line (ADSL), wireless local area network (WLAN IEEE 802.11a,g), high performance radio local area network (HIPERLAN 2), and worldwide interoperability for microwave access (WiMAX IEEE 802.16). However, the transmit signal in OFDM system has a high peak-to-average power ratio (PAPR), one of the major drawbacks of multicarrier transmission, and therefore high dynamic range is required in both the digital to analog converter (DAC) and the power amplifier (PA) for proper operation. Otherwise, the nonlinearities of PA cause out-of-band distortion and increase in bit error rate (BER). Therefore, the reduction in PAPR in OFDM system is desirable in order to obtain power efficiency and increase BER performance. In this paper, a new parametric PAPR reduction technique, L₂-by-3 transform from sliding norm transform (SNT) family is proposed. Based on its parameter, a significant PAPR reduction is obtained. This paper presents the analysis of power saving and computational complexity of the proposed method L₂-by-3 and comparison to two other methods; selected mapping and partial transmit sequence.     

Architecture analysis of enterprise systems modifiability - Models, analysis, and validation

Enterprise architecture (EA) models can be used in order to increase the general understanding of enterprise systems and to perform various kinds of analysis. This paper presents instantiated architectural models based on a metamodel for enterprise systems modifiability analysis, i.e. for assessing the cost of making changes to enterprise-wide systems. The instantiated architectural models detailed are based on 21 software change projects conducted at four large Nordic companies. Probabilistic relational models (PRMs) are used for formalizing the EA analysis approach. PRMs enable the combination of regular entity-relationship modeling aspects with means to perform enterprise architecture analysis under uncertainty. The modifiability metamodel employed in the analysis is validated with survey and workshop data (in total 110 experts were surveyed) and with the data collected in the 21 software change projects. Validation indicates that the modifiability metamodel contains the appropriate set of elements. It also indicates that the metamodel produces estimates within a 75% accuracy in 87% of the time and has a mean accuracy of 88% (when considering projects of 2000 man-hours or more).     

A modeling approach on the TelosB WSN platform power consumption

Substantial characteristics of wireless sensor networks, such as autonomy and miniature size, are achieved at the expense of restricted energy resources. Optimal resource management is thus among the most important challenges in WSNs development and its success requires accurate and practical models based on detailed insight concerning the factors contributing to the overall power consumption of a WSN mote. To achieve such awareness, that will enable models development, appropriate measuring test-beds and methodologies are needed, facilitating reliable and accurate power consumption measurements of critical functionalities.To cover the need for energy models that precisely define the power consumption behavior of WSN hardware platforms, this paper contributes with a measuring methodology including three steps: the design and implementation of a measuring system for a wide range of power consumption thresholds, the identification, isolation and measurement of elementary functionalities of a WSN platform with respect to their contribution to the overall mote power consumption, and the extraction of valuable conclusions based on the respective measurements resulting in the composition of a practical, yet accurate power consumption model.     

提高牵引供电电能质量技术的研究

在分析输电线路中TCSC与SVC的设计所存在的相互矛盾的基础上,针对牵引供电系统中动态并联补偿装置与串联补偿装置的协调控制问题进行研究.在节能的前提下,得出了各补偿装置补偿容量的优化控制策略,并提出了一种动态并联补偿装置的定性定量控制技术.该控制系统有效地提高了补偿的速度和精度,并具有良好的跟踪负载变化的性能,对我国电气化铁路的改造具有重要意义.     

The relation between EA effectiveness and stakeholder satisfaction

Enterprise Architecture (EA) is increasingly being used by large organizations to get a grip on the complexity of their business processes, information systems and technical infrastructure. Although seen as an important instrument to help solve major organizational problems, effectively applying EA seems no easy task. Active participation of EA stakeholders is one of the main critical success factors for EA. This participation depends on the degree in which EA helps stakeholders achieve their individual goals. A highly related topic is effectiveness of EA, the degree in which EA helps to achieve the collective goals of the organization. In this article we present our work regarding EA stakeholder satisfaction and EA effectiveness, and compare these two topics. We found that, regarding EA, the individual goals of stakeholders map quite well onto the collective goals of the organization. In a case study we conducted, we found that the organization is primarily concerned with the final results of EA, while individual stakeholders also worry about the way the architects operate.     

Semantic Web computing in industry

The Semantic Web has attracted significant attention during the last decade. On the one hand, many research groups have changed their focus towards Semantic Web research and research funding agencies particularly in Europe have explicitly mentioned Semantic Web in their calls for proposals. On the other hand, industry has also begun to watch developments with interest and a number of large companies have started to experiment with Semantic Web technologies to ascertain if these new technologies can be leveraged to add more value for their customers or internally within the company, while there are already several offers of vendors of Semantic Web solutions on the market. The essence of the Semantic Web is to structure Web-based information to make it more interoperable, machine-readable and thereafter to provide a means to relate various information concepts more easily and in a reusable way. The Semantic Web acts as an additional layer on the top of the Web, and is built around explicit representations of information concepts and their relationships such as ontologies and taxonomies. Furthermore, Semantic Web technologies are not only valuable on an open environment like the Web, but also in closed systems such as in industrial settings. Hence, these technologies can be efficiently deployed for domains including Web Services, Enterprise Application Integration, Knowledge Management and E-Commerce, fulfilling existing gaps in current applications. This paper focuses on this synthesis between Semantic Web technologies and systems problems within industrial applications. There will be a short review of Semantic Web standards, languages and technologies followed by a more detailed review of applications of Semantic Web computing in industry. The paper covers theoretical considerations as well as use cases and experience reports on the topic, and we also present some current challenges and opportunities in the domain.