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951.
The broad acceptance of mobile technology has undoubtedly created new opportunities in communication. The proposed environment attempts to enhance the information flow among the members of a department and, furthermore, to provide a test-bed mobile Web application for students undertaking Internet technologies courses. The key ideas are to support the educational process to provide auxiliary access to educational information sources, such as announcements, course schedules, grades, and user directory details. As a second system integration step, additional mobile Web services were introduced, such as application forms of the department's administration office, project assignment, and discussion groups. Technological evaluation and students' feedback indicate that the proposed solution is both efficient in communication perspective and effective for student involvement in the mobile Web initiative. Future steps include multimedia messages (MMS) integration and third-generation (3G)-based information delivery. 相似文献
952.
953.
E-enforcement, or electronic enforcement, is the use of electronic tools in law enforcement. We shall distinguish between the first and second generations of e-enforcement. The first generation of e-enforcement tools provided means of "automated enforcement". This article is based on our research into the effects of two forms of second generation e-enforcement: the digital tachograph and 'Weigh in Motion' (WIM). The digital tachograph replaces the analog tachograph in all heavy goods vehicles within the European Union. The equipment registers drivers' driving and rest times. Weigh in Motion with Video (WIM-Vid) is a system involving sensors in the road and cameras, which detect and register overloading of heavy goods vehicles. The WIM-Vid system was developed and implemented in the Netherlands and is currently attracting international attention. We compare the situation prior to the introduction of these e-enforcement measures to the situation after the introduction of e-enforcement. 相似文献
954.
This paper presents a computer model for the probabilistic representation of wind farms generation for reliability studies, which can provide an annual estimation of energy production and calculate several performance indexes. The model combines the stochastic characteristics of wind speed with the operational information of the turbines, such as the failure and repair rates, representing the wind farm by a Markov process. The simulations are made with real time series of wind speed of several Brazilian regions and actual turbine models. The influence of some wind farm and installation site characteristics on the results are evaluated, such as the wind speed statistical clustering technique, the number and type of the turbines, and the failure and repair rates. The results obtained reproduce successfully the behavior of the components considered in the model 相似文献
955.
S.M. Brahma 《Power Delivery, IEEE Transactions on》2006,21(3):1148-1153
This paper describes a new iterative method to locate a fault on a single multiterminal transmission line. The method uses synchronized voltage and current measurements from all terminals. Using positive-sequence components of the prefault and postfault waveforms, positive-sequence source impedances are estimated. Using these source impedances and the line data, the positive-sequence bus impedance matrix (Z/sub bus/) is formed. Using the properties of Z/sub bus/, an iterative algorithm is proposed. The algorithm first identifies the faulted section and then locates the fault on this section. This algorithm is applied to the data obtained from the Electromagnetic Transients Program simulation of a multiterminal transmission line. The simulation results show that the distinctive features of this method are that it performs with very high accuracy for all types of faults at different fault locations and is practically immune to fault resistance. 相似文献
956.
In this paper, we propose a method for the allocation of fixed (capital and nonvariable operation and maintenance) costs at the medium voltage (MV) distribution level. The method is derived from the philosophy behind the widely used MW-mile methodology for transmission networks that bases fixed cost allocations on the "extent of use" that is derived from load flows. We calculate the "extent of use" by multiplying the total consumption or generation at a busbar by the marginal current variations, or power to current distribution factors (PIDFs) that an increment of active and reactive power consumed, or generated in the case of distributed generation, at each busbar, produces in each circuit. These PIDFs are analogous to power transfer distribution factors (PTDFs). Unlike traditional tariff designs that average fixed costs on a per kWh basis across all customers, the proposed method provides more cost-reflective price signals and helps eliminate possible cross-subsidies that deter profitable (in the case of competition) or cost-effective (in the case of a fully regulated industry) deployment of DG by directly accounting for use and location in the allocation of fixed costs. An application of this method for a rural radial distribution network is presented. 相似文献
957.
958.
Using the synthesized agent propachlor (N-isopropyl-2-chloroacetanilid) labelled with 14C, methodical investigations revealed an extremely high steam volatility not being assumed before because of the low vapour pressure. The method of steam distillation basing on this fact is of universal application to the processing of maize, potatoes, water, and soil, in which propachlor could be quantitatively determined by gas chromatography with a detection sensitivity of 0.02 ppm. Furthermore, this methods allows a simple purification of the raw product of synthesis containing impurities up to 20%. Propachlor codistilled with steam had a purity of more than 99%. Possibly, the high steam volatility of propachlor could have economic and toxicological consequences as to its application (volatilization in the open air with a high atmospheric humidity along with high temperatures). Therefore, an investigation of the steam volatility in the general screening programme for new agents is to be recommended in addition to the usual investigations of steam pressure. 相似文献
959.
A new analytical method has been developed for the determination of the reactive lysine content of soya bean protein. The method is based on the reaction of the free basic groups of the protein with 1-phenylazo-2 naphthol-6,8 disulphonic acid. With regard to the stoichiometry of the procedure, it has been proved, contrary to earlier reports, that the basic amino acids, histidine, arginine and lysine, each combine with one mole of the dye. After acylation with propionic anhydride lysine alone loses its dye reactivity. The usefulness of the proposed method has been demonstrated by the determination of the reactive lysine content of several untreated, heat-treated and acid-treated soya bean samples. The results show that heat damage of about 5% in reactive lysine content can be measured in 1·5 h with good reproducibility. 相似文献
960.