Energy sector planning using multiple-index pinch analysis

Pinch analysis was initially developed as a methodology for optimizing energy efficiency in process plants. Applications of pinch analysis applications are based on common principles of using stream quantity and quality to determine optimal system targets. This initial targeting step identifies the pinch point, which then allows complex problems to be decomposed for the subsequent design of an optimal network using insights drawn from the targeting stage. One important class of pinch analysis problems is energy planning with footprint constraints, which began with the development of carbon emissions pinch analysis; in such problems, energy sources and demands are characterized by carbon footprint as the quality index. This methodology has been extended by using alternative quality indexes that measure different sustainability dimensions, such as water footprint, land footprint, emergy transformity, inoperability risk, energy return on investment and human fatalities. Pinch analysis variants still have the limitation of being able to use one quality index at a time, while previous attempts to develop pinch analysis methods using multiple indices have only been partially successful for special cases. In this work, a multiple-index pinch analysis method is developed by using an aggregate quality index, based on a weighted linear function of different quality indexes normally used in energy planning. The weights used to compute the aggregate index are determined via the analytic hierarchy process. A case study for Indian power sector is solved to illustrate how this approach allows multiple sustainability dimensions to be accounted for in energy planning.     

一种基于高阶特征表示的图像分类方法

传统高阶特征构建方法需对局部特征进行两两匹配,随着阶数的增加,从而导致组合爆炸问题。为此,提出一种高阶特征组合表示方法。将图像划分为多个网格,每个网格内的尺度不变特征转换组合成高阶特征组合。同一个网格内tf-idf值最大的特征作为主特征,其余特征作为子特征,将主特征与子特征之间的夹角作为特征空间信息。通过高阶特征组合的视觉距离和几何距离匹配高阶特征,并结合支持向量机进行图像分类实验,结果表明,该方法分类准确率提高了约4%,可有效避免组合爆炸问题。     

基于改进遗传模拟退火算法的WSN路径优化

针对无线传感器网络路径优化问题,提出了一种改进的最优保存的遗传模拟退火算法。利用LEACH算法构建初始路由表,使用GASA的高效率搜索,将路由计算和遗传演化计算同时进行,并直至寻找到近似最优路径为止。将最优保存遗传算法和模拟退火算法相结合,引入自适应的概率变化,有效地解决了这两种算法的早熟现象和时间问题。仿真实验表明,该算法有效地解决了无线传感器路径优化问题,具有定位准确、节能和搜索能力较强等优点。     

Designing a secure e-tender submission protocol

This paper investigates the fundamental difference between a simple e-tender box and a traditional physical tender box, and highlights a series of security traps created by the functional differences. Based on our findings, we have defined the security requirements for an e-tender submission protocol. We also discuss functional limitations of cryptographic technologies. As a result, two secure e-tender submission protocols are proposed which enable a secure e-tender submission. Protocols are assumed to run under the condition that all tendering parties (principal and tenderers) are dishonest players. Our informal and formal security analysis show that these protocols meet their security goals under well known collusion scenarios. Because security is a process not a product, our approach will have broad industry application for developing secure electronic business processes in areas other than e-tendering.

Delivery of video mail on the World Wide Web

This study was initiated to examine the feasibility of providing multimedia mail, in particular video mail, on the existing World Wide Web platform. In this instance, the Web browser will act as the user agent of the mailing system. With this, users will be able to compose, send and read video mail directly on the Web. This paper examines a number of possible system architectures that can be employed for the development of video mail. Based on the following key issues: portability of system, flexibility of system, Internet standard support, security and authentication, and message compression and storage, a final architecture was selected to build video mail. The approach taken is that the system will be interfaced to the Web using a standard HyperText Transfer Protocol (HTTP) server and a standard Web browser. This is achieved through the use of Common Gateway Interface (CGI) programs and forms which reside in a standard HTTP server to provide the functionality of video mail, and a separate mail server for the storage and management of messages. This will cause the HTTP server to behave as if it is an electronic mail (E-mail) system. Video mail has been successfully implemented at the School of Applied Science, Nanyang Technological University, Singapore. The development work has been carried out on a Sun SPARC5 workstation and the Typhoon relational database system was used to construct the mail server. All software codes were written in C or C++. A video capturing application used in conjunction with a SunVideo card has been developed for video and audio recording. The paper also addresses implementation issues pertaining to the use of CGI programs, mail server development, and video and audio management.     

Compositional and structural study of ash deposits spatially distributed in superheaters of a large biomass-fired CFB boiler

Recognizing the nature and formation progress of the ash deposits is essential to resolve the deposition problem hindering the wide application of large-scale biomass-fired boilers. Therefore, the ash deposits in the superheaters of a 220 t/h biomass-fired CFB boiler were studied, including the platen (PS), the high-temperature (HTS), the upper and the lower low-temperature superheaters (LTS). The results showed that the deposits in the PSs and HTSs were thin (several millimeters) and compact, consisting of a yellow outer layer and snow-white inner layer near the tube surface. The deposits in the upper LTS appeared to be toughly sintered ceramic, while those in the lower LTS were composed of dispersive coarse ash particles with an unsintered surface. Detailed characterization of the cross-section and the initial layers in the deposits revealed that the dominating compositions in both the PSs and the HTSs were Cl and K (approximately 70%) in the form of KCl. Interestingly, the cross-section of the deposition in the upper LTS exhibited a unique lamellar structure with a major composition of Ca and S. The contents of Ca and Si increased from approximately 10% to approximately 60% in the deposits from the high temperature surfaces to the low temperature ones. It was concluded that the vaporized mineral matter such as KCl played the most important role in the deposition progress in the PS and the HTS. In addition, although the condensation of KCl in the LTSs also happened, the deposition of ash particles played a more important role.     

Air pollution,economic spillovers,and urban growth in China

This paper empirically tests the interactive effects of air pollution and economic spillovers in Chinese cities from 2003 to 2010. The results show that Chinese cities benefit from the economic spillovers from surrounding cities, but bear the costs of negative air pollution externalities created by neighboring cities. We use wind direction and the administrative boundaries of provinces to disentangle possible multicollinearity between air pollution emissions and economic spillovers across cities. However, the results could not reject the growth-restricting effects of air pollution from neighboring cities. The results imply that the development of a city surrounded by polluters is likely to be constrained.     

基于PLC的超声波探头自动定位系统

为实现大型回转件超声波探伤系统中探头的自动定位,研制了一种基于可编程逻辑控制器(PLC)的闭环控制系统。根据工业现场的实际环境,设计了以带AD转换模块的小型PLC为控制核心,利用位置接近开关、微型继电器以及直流小电机阵列来实现对超声波探头对工件表面的实时跟踪,保障无损检测信号的采集精度。介绍了系统的硬件(控制电路及机构设计)组成和基于PLC编程器的软件开发。