Ecological Optimization Performance of An Irreversible Quantum Otto Cycle Working with an Ideal Fermi Gas

The model of an irreversible Otto cycle using an ideal Fermi gas as the working fluid, which is called as the irreversible Fermi Otto cycle, is established in this paper. Based on the equation of state of an ideal Fermi gas, the ecological optimization performance of an irreversible Fermi Otto cycle is examined by taking an ecological optimization criterion as the objective, which consists of maximizing a function representing the best compromise between the exergy output and exergy loss (entropy production) of the cycle. The relationship between the ecological function E and the efficiency η is studied. Three special cases are discussed in detail. The results obtained herein may reveal the general performance characteristics of the irreversible Fermi Otto cycle.     

The Influence of Quantum Degeneracy on the Performance of a Fermi Brayton Engine

The influence of quantum degeneracy on the performance of a Brayton engine using an ideal Fermi gas as the working substance is investigated, based on the theory of statistical mechanics. The general expressions of the efficiency and work output of the engine cycle are derived. The maximum work output and the corresponding efficiency are calculated. The bound of the pressure ratio of the two constant-pressure processes that the Brayton engine cycle can be operated normally is determined. Some important characteristic curves of the cycle, such as the work output versus pressure ratio curves, the efficiency versus pressure ratio curves, the maximum work output ratio versus temperature of the heat reservoirs curves, and so on, are presented. Three special cases are discussed in detail. The results obtained may reveal the general performance characteristics of a Brayton engine working with an ideal Fermi gas.     

Power Density Analysis for a Regenerated Closed Brayton Cycle

In this paper, the power density, defined as the ratio of power output to the maximum specific volume in the cycle, is set as the objective for performance analysis of an irreversible, regenerated and closed Brayton cycle coupled to constant-temperature heat reservoirs from the viewpoint of finite time thermodynamics (FTT) or entropy generation minimization (EGM). The analytical formulae about the relations between power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the regenerator, the irreversible compression and expansion losses in the compressor and turbine, and the pressure loss in the pipe. The results obtained are compared with those obtained by using the maximum power criterion. The influences of some design parameters, including the effectiveness of the regenerator, the temperature ratio of heat reservoirs, the effectivenesses of heat exchangers between working fluid and heat reservoirs, the efficiencies of the compressor and the turbine, and the pressure recovery coefficient, on the maximum power density are illustrated by numerical examples, and advantages and disadvantages of maximum power density design are analyzed. When heat transfers between working fluid and heat reservoirs are carried out ideally, the results of this paper coincide with those obtained in recent literature.     

理想情况下混合态量子系统的Lyapunov控制策略

本文在假定被控系统具有理想条件的前提下,研究了带有附加自由度的Lyapunov方法在混合态量子系统中的应用问题.基于LaSalle不变原理,我们推导出了控制场作用下系统的最大不变集、以及始于任一初始态的系统轨线的收敛状态集,给出了系统对于最大不变集中任一目标态渐近稳定化的、自由度的构造原则.为了清晰阐述自由度的构造原则,我们在一个两能级的量子系统上进行了数值仿真实验,仿真结果同时也表明了本文所得理论结果的合理性.     

Life Cycle Analysis of an Ada Project

How does Ada affect cost? A cost-prediction model developed during this project is compared with six popular models to reveal Ada's effect on design, coding, and testing.     

Performance Optimization of a Combined Heat Pump Cycle

A steady flow combined heat pump cycle model with heat resistance, heat leakage and internal irreversibility is built in this paper. The optimal performance of the model is studied. The relation between optimal heating load and coefficient of performance (COP), as well as the maximum COP and the corresponding heating load are derived.     

Aggregation of an Autonomous System with an Attracting Cycle

Automation and Remote Control - We consider a set of autonomous systems in each of which a case that is nondegenerate for a periodic solution is realized. The problem of aggregating these systems...     

燃气-蒸汽联合循环机组在热电联产中的应用

简要介绍了蒸汽轮机循环、燃气-蒸汽联合循环与燃气轮机循环的不同之处,并在此基础上,阐述了蒸汽轮机热电联产与联合循环热电联产的区别。介绍了燃气-蒸汽联合循环设备,阐述了燃气－蒸汽联合循环在热电联产中的应用和联合循环热电联产的优点,以期为今后燃气-蒸汽联合循环机组的有效应用提供一定的参考。     

一种提供QoS的IP/ATM路由器的设计与性能分析

该文介绍了一种多于网ＩＰ／ＡＴＭ路由器的设计方案,给出了它的软件系统框架,提出了一种ＩＰ前传机制,ＩＰ流交换,提出了一种可适应非安全循环服务规则（ＡＩＣＳ）来减轻突发性流量对时延的影响,保证端到ＱｏＳ需求,并利用计算机仿真对时延进行了性能分析。     

一个面向对象数据库系统的TPC-C测试与分析

文章介绍了一个著名的在线事务处理系统性能测试标准TPC-C及其在面向对象数据库管理系统Fish上的设计与实现,并基于实验结果对影响数据库系统性能的主要因素进行了验证和分析.     

基于GT-Power对天然气/氢气发动机的性能分析

为了分析在HCNG发动机中不同掺氢比对动力性能和排放性能的影响,提高发动机的燃烧效率等性能,利用GT-Power软件建立EQD180N-30涡轮增压发动机仿真模型.针对在不同的掺氢比情况下,分析过量空气系数和点火提前角对发动机的动力性、燃油经济性和排放性能的影响.进行了仿真实验,结果表明体积掺氢比在20%时,发动机具有较好的综合性能.在保持动力性变化不大的情况下,有着较好的排放性能.计算结果与实际结果比较吻合,误差较小,并可以得到在不同工况下发动机的最佳掺氢比,对发动机控制系统的设计可提供重要依据.     

Performance of a Lattice Quantum Chromodynamics kernel on the Cell processor

The implementation of a proof-of-concept Lattice Quantum Chromodynamics kernel on the Cell processor is described in detail, illustrating issues encountered in the porting process. The resulting code performs up to 45 GFlop/s per socket (without inter-node parallel communications), indicating that the Cell processor is likely to be a good platform for future Lattice QCD calculations.     

一种改进MVI-CFAR检测器的性能分析

VI-CFAR检测器在均匀环境和非均匀环境下均具有较强的自适应性,但若前后两个参考滑窗均存在干扰目标时,VI-CFAR检测性能急剧下降。为克服该问题,本文采用有序统计平均CFAR和有序统计选小CFAR来替代VI-CFAR中最小选择CFAR。所提出的算法不但解决了干扰目标位置随机分布的问题,还解决了当其中一个滑窗的干扰目标数超过最大容限时检测性能下降的问题。在参考滑窗中干扰目标个数与扰噪比均不相同的情况下,分析了统计量VI的变化,有助于评估和设计VI-CFAR类检测器在多目标环境下抗干扰目标的最大容限。仿真结果表明,该改进算法提高了VI-CFAR在多目标环境下的鲁棒性,与其他改进算法相比,其排序处理时间降低一倍。     

MFSK信号在循环频率处基于一阶循环矩检测器的性能分析

频谱感知是认知无线电的关键技术之一。在信噪比较低并且对主用户信号先验知识知道较少的情况下,主用户检测对于认知无线电设备来说是非常重要的。对有噪MFSK信号在循环频率处基于一阶循环矩检测器的性能进行了较为深入的理论分析,并推导了采样长度有限时噪声一阶循环矩幅度及有噪MFSK信号在循环频率处一阶循环矩幅度的概率密度函数公式;据此给出了该检测器的ROC特性曲线计算方法。理论分析表明,随着采样长度的增加,该检测器的性能显著提高;同等条件下,随着MFSK信号进制数M的增加,检测器性能有所下降。     

Quantum speedup of an atom coupled to a photonic-band-gap reservoir

For a model of an atom embedded in a photonic-band-gap reservoir, it was found that the speedup of quantum evolution is subject to the atomic frequency changes. In this work, we propose different points of view on speeding up the evolution. We show that the atomic embedded position, the width of the band gap and the defect mode also play an important role in accelerating the evolution. By changing the embedded position of the atom and the coupling strength with the defect mode, the speedup region lies even outside the band-gap region, where the non-Markovian effect is weak. The mechanism for the speedup is due to the interplay of atomic excited population and the non-Markovianity. The feasible experimental system composed of quantum dots in the photonic crystal is discussed. These results provide new degree of freedoms to depress the quantum speed limit time in photonic crystals.     

关于微机控制系统采样周期的分析

本文全面地分析了采样周期对微机控制系统的稳定性、动态品质、抗干扰能力、数字PID的控制作用的影响,并提出了采样周期可能影响最小相位系统变成非最小相位系统的新论点。     

程序的cache使用效率分析

评价程序的存储效率是提高用户程序性能的重要手段。该文首先提出了程序的装入因子的概念,并据此分析了矩阵乘法;其次,根据时间局部化原则,提出了一种“最小时间差方法”,该方法可以有效地减少cacheline的装入数目;最后,为了评价程序的存储延迟,提出了程序数据相关性的概念,据此给出了计算装入因子的公式,用于分析程序的存储效率。这样就可以用big-O模型来表达程序的时间复杂性,并用装入因子来表达程序的存储访问复杂性。     

轻量级嵌入式数据中间件的实现和性能分析

随着嵌入式Internet时代的到来,嵌入式设备通过与网络的结合实时地互相交换信息已经初步发展起来,因此对嵌入式系统的数据传输速度提出了要求。论文论述了在嵌入式系统中使用三层客户机/服务器结构设计来实现嵌入式数据中间件,有效地改善了多用户对数据库的访问性能,优化了网络传输性能,提高了响应的实时性。     

卡尔曼滤波器性能分析

本文提出了用实际的估计误差协方差来评价卡尔曼滤波器的性能的思想,并针对单输入单输出系统,分析了在初始条件,误差模型部分或全部不精确已知的情况下,卡尔曼滤波器的性能,得到了一些有用的结论。