面向数据密集应用的云计算服务架构

提出了一种具有云计算特点的可伸缩的服务器架构,通过采用模块化的方式有效地分割服务功能,能以对用户透明的方式满足三维网络应用的各种存储和带宽的需要。将该方案在一个三维虚拟现实项目中进行测试,结果表明,该方案有较好的伸缩性和效率。     

Structure evolution,dielectric,and conductivity behavior of(K0.5Na0.5)NbO3-Bi(Zn2/3Nb1/3)O3 ceramics

(1-x)K0.5Na0.5NbO3-xBi(Zn2/3Nb1/3)O3 ((1-x)KNN-xBZN,x =0.010,0.015,0.020,0.025,and 0.030) lead-free ceramics were fabricated via a traditional solid-state metho...     

基于小波的输油管道泄漏信号去噪处理

基于小波分析的噪声消除方法,研究负压波法提取泄漏信号的去噪。首先介绍基于小波分析的噪声消除基本原理,然后运用小波方法对实测信号进行具体处理,在信号处理过程中考虑了不同小波基和不同的分解层数对去噪结果的影响。实验证明,合理选择小波基和小波分解的层数,能够有效滤除泄漏信号中的噪声。     

Giant dielectric response and charge compensation of Li- and Co-doped NiO ceramics

Dielectric properties and charge compensation of Li and Co co-doped NiO (LCNO) ceramics prepared by a simple sol–gel route have been investigated. The concentration of Co makes a great influence on microstructure, dielectric properties and charge compensation mechanism of the LCNO ceramics. Grain size of the ceramics increases from 5.6 μm to 7.2 μm with dependence on Co concentration. By using a complex impedance analysis at different temperatures, the samples exhibit an electrically heterogeneous structure, which is responsible for a giant dielectric permittivity. The relationship between the activation energies of dielectric relaxation and conduction and charge compensation mechanism in this system were discussed.     

粒子群优化算法在多目标优化中的应用与仿真

该文结合经济多目标优化的实际问题,对粒子群算法的初始化进行了改进,在给定范围内进行初始化,并且对于复杂域约束优化问题,给出了其实现与仿真。     

Modeling and validation of the iodine‐sulfur hydrogen production process

The iodine‐sulfur thermochemical water‐splitting cycle (I‐S process) is one of the highly efficient, CO₂‐free, massive hydrogen production methods. We simulated the I‐S process through commercial software programs Aspen Plus and OLI database with the aid of self‐developed models to analyze the overall running status of the process and to decrease the investment and time consumption of experiments. A two‐phase separator model operating at 353 K and an electro‐electrodialysis (EED) cell model working at 338 K were built on the basis of experimental data. The entire flow sheet of the I‐S process was modeled based on the two self‐developed models. The simulation models were validated through the experimental results obtained from the closed cycle I‐S facility (IS‐10) in our laboratory. By employing the simulation program, sensitivity analyses of the important parameters in the process were carried out, including the ratio of the distillate to the feed rate of the H₂SO₄ distillation column, reflux ratio of the H₂SO₄ column, H₂SO₄ conversion ratio, HI molality in the EED cathode outlet stream, and HI mole fraction in the liquid and vapor distillates of the HI distillation column. The key parameters significantly affecting the input duty were determined; that is, the ratio of the distillate to the feed rate of the H₂SO₄ distillation column and the HI molality in the EED cathode outlet stream. The optimal values of the analyzed parameters were also discussed. The simulation program we developed is a useful tool that can evaluate and optimize the I‐S process. © 2013 American Institute of Chemical Engineers AIChE J 60: 546–558, 2014     

电泳沉积技术制备铁电陶瓷薄膜的研究进展

综述了电泳沉积技术在制备铁电陶瓷薄膜方面的最新研究进展,讨论了陶瓷特性、电压、分散剂、热处理时间等因素对电泳沉积铁电薄膜性能的影响.最后展望了电泳沉积技术制备铁电陶瓷薄膜的进一步发展.     

Preparation and Electric Properties of Bi0.5Na0.5TiO3–Bi(Mg0.5Ti0.5)O3 Lead‐Free Piezoceramics

Lead‐free BNT‐based piezoceramics, (1?x)Bi_0.5Na_0.5TiO₃–xBi(Mg_0.5Ti_0.5)O₃ [(1?x)BNT–xBMT] (0.00 ≤ x ≤ 0.06) binary system, were synthesized using a conventional ceramic fabrication method. Effect of Bi(Mg_0.5Ti_0.5)O₃ (BMT) substitution on room temperature (RT) crystal structure, and temperature dependence of electric properties were investigated. The XRD indicates that a pure perovskite phase is formed. The introduction of BMT decreases E_C of BNT from 7.3 to 4.0 kV/mm, and increases d₃₃ from 58 pC/N to 110 pC/N for the x = 0.05. The system shows a typical ferroelectric (FE) polarization loop P(E) and butterfly bipolar strain‐electric S(E) curve at RT. For the composition of 0.95BNT–0.05BMT antiferroelectric (AFE) phase appears near 80°C, characterized by a constricted P(E) loop and altered bipolar S(E) butterfly, and gradually prevails with increasing temperature. Temperature dependence of dielectric constant shows that T_C increases from 310°C for pure BNT to 352°C for the x = 0.05. The results indicate that the piezoelectric properties of BNT have been improved by means of Bi(Mg_0.5Ti_0.5)O₃ substitution.     

基于动态电压补偿的VSG电流平衡及峰值电流控制

虚拟同步发电机(VSG)能够实现新能源机组友好并网。然而,传统的VSG技术主要适用于电网电压平衡工况,这使得VSG在电压不平衡情况下面临输出电流不平衡及过流等问题,为此提出一种基于动态电压补偿的VSG平衡电流控制架构及方法。通过负序电流抑制和峰值电流抑制策略,分别生成对应的补偿电压,使得VSG在电压不平衡时仍能输出平衡电流,且可抑制电网电压跌落瞬间的暂态冲击,以及确保稳态运行时的电流不超过安全阈值。同时,所提控制方法并未改变VSG等效为电压源的属性,保留了VSG的电压支撑能力。不同工况下的仿真测试结果验证了所提出控制方法的正确性和有效性。