基于Parlay/OSA的FreeAd业务研究与实现

Parlay/OSA API编程接口的开放特性给电信网络新业务的开发带来了方便,本文给出了基于OSA API开发WAP PUSH形式的免费手机广告的方法——FreeAd,并在Parlay网关仿真平台Ericsson NRG下完成了对该业务的设计和实现.对用户进行仿真工作具有实际意义.     

有限热源铁电埃里克森制冷机的优化分析

根据铁电晶体的热力学性质,应用有限时间热力学理论,探讨有限热源、热阻和非理想回热损失对一类铁电埃里克森制冷机的影响,导出铁电晶体埃里克森制冷机的基本优化关系,由此讨论制冷机的各种优化性能,所得结论可为铁电晶体埃里克森制冷机的研制和优化设计提供新的理论指导.     

Ecological optimization of an irreversible Ericsson cryogenic refrigerator cycle

The ecological optimization and parametric study of an irreversible Ericsson cryogenic refrigerator cycle with finite heat capacities of external reservoirs is studied. The ecological function is defined as the cooling load minus the loss of the cooling load (the irreversibility) due to the entropy generation rate. The ecological function is optimized with respect to working fluid temperatures and the values of the cooling load, power input, the loss rate of the cooling load and COP are calculated for a typical set of operating parameters. The effects of different operating parameters on the ecological function, cooling load, the loss rate of the cooling load and COP are studied. The loss rate of the cooling load and the power input are found to be increasing functions of the cycle temperature ratio and decreasing functions of COP while the COP is found to be a decreasing function of the cycle temperature ratio. On the other hand, there exist the optimal values of the cycle temperature ratio and COP at which the ecological function and cooling load attain their maximum values. Also the ecological function and the cooling load are found to be increasing functions of the sink‐side heat capacitance rate and the effectiveness on the source‐, sink‐, and regenerative‐side heat exchangers while the decreasing functions of the source‐side heat capacitance rate. Copyright © 2005 John Wiley & Sons, Ltd.     

模拟B网并入A网的技术方案

本主要就模拟B网并入A网的可行性及三种技术方案的优缺点进行讨论分析,力求寻找既简例、经济、用户又可以接受的方法,实现B网用户平稳并入A网。     

Thermodynamics of magnetic refrigeration

A comprehensive treatment of the thermodynamics of cyclic magnetic refrigeration processes is presented. It starts with a review of the work, heat and internal energy of a magnetized specimen in a magnetic field, and a list of the thermodynamic potentials is given. These are based on the very recent discovery of an alternative Kelvin force. It is shown that this force is compatible with the internal energy proposed by Landau and Lifshitz. New formulas for the specific enthalpies are presented. Cyclic processes are discussed in detail, e.g. the Brayton, Ericsson and Carnot cycles. Magnetic refrigeration and magnetic heat pump cycles are preferably designed by applying the cascade or/and regeneration principle. Cascade systems allow wider temperature ranges to be obtained. The main objective of this article is to yield a theoretical basis for an optimal design of new magnetic refrigeration and heat pump devices.     

High Power Density Pyroelectric Energy Conversion in Nanometer-Thick BaTiO3 Films

Solid-state pyroelectric nanomaterials can be used for thermal-to-electrical energy conversion in the presence of temperature fluctuations. This article reports investigation of energy conversion in a 200 nm thick BaTiO₃ film using the pyroelectric Ericsson cycle at cycle frequencies up to 3 kHz. The high cycle frequencies were achieved due to the low thermal mass of the nanometer-scale film, unlike previous studies in which the electrical power output was limited by the rate of heat transfer through the pyroelectric material. A microfabricated platform that allowed precise thermal and electrical cycling enabled us to study the effect of electric field range, temperature oscillation amplitude, and cycle frequency on the electrical power output from pyroelectric Ericsson cycles. We measured a maximum power density of 30 W/cm³ for a temperature range 20–120°C and electric field range 100–125 kV/cm, which represents a significant improvement over past work on pyroelectric cycles. The approach presented in this article could lead to high-power waste heat harvesting in systems with high-frequency temperature oscillations.     

Energy, exergy and cost analysis of a micro-cogeneration system based on an Ericsson engine

Hot air engines (Stirling and Ericsson engines) are well suited for micro-cogeneration applications because they are noiseless, and they require very low maintenance. Ericsson engines (i.e. Joule cycle reciprocating engines with external heat supply) are especially interesting because their design is less constrained than Stirling engines, leading to potentially cheaper and energetically better systems. We study the coupling of such an Ericsson engine with a system of natural gas combustion. In order to design this plant, we carry out classic energy, exergy and exergo-economic analyses. This study does not deal with a purely theoretical thermodynamic cycle. Instead, it is led with a special attempt to describe as accurately as possible what could be the design and the performance of a real engine. It allows us to balance energetic performance and heat exchanger sizes, to plot the exergy Grassmann diagram, and to evaluate the cost of the thermal and electric energy production. These simple analyses confirm the interest of such systems for micro-cogeneration purposes. The main result of this study is thus to draw the attention on Ericsson engines, unfortunately unfairly fallen into oblivion.     

磁埃里克森制冷机的火用经济优化性能

研究存在热阻和非理想回热的磁埃里克森制冷机的火用经济优化性能,得到一些新的性能参数,并揭示了它与生态学优化性能间的联系,所得结论可为磁埃里克森制冷机研制和优化设计提供新的理论指导.     

基于J2ME的手机围棋游戏的设计

论文以围棋游戏为基础,采用当前移动领域比较流行的J2ME技术和LCDUI技术,实现了人机对战游戏,游戏设计过程中对提子功能、游戏对战、加载棋盘、自定义棋盘设置等核心技术作了详细的分析和设计,游戏在Sony Ericsson模拟器环境上进行了仿真实验,实验结果表明,该游戏具移植性强、加载速度快、棋盘设置灵活、占用资源少、数据传输稳定等优点.     

热源温度对回热式室温磁Ericsson制冷循环性能的影响

结合分子场理论和磁系统热力学知识,分析了回热式室温磁Ericsson制冷循环中热量和磁熵的关系,重点研究了热源温度对铁磁质磁Ericsson制冷循环性能的影响.利用典型室温磁制冷材料Gd进行了数值计算,得到以下结论:居里点附近是循环中的重要转折点,TL低于居里点会出现△Q＜0的情况,一旦高于居里点则只有△Q＞0的情况;TL越高对应的高温热源最大值THmax越高;相同高、低温热源条件下,磁场越大COP变化率越小.