数据中心供电系统的新技术应用研究

随着IDC及云计算的快速发展,如何建设绿色节能和经济高效的数据中心已经成为国内各大运营商及政企关注的重点。传统UPS供电系统因效率低、能耗高、后备铅酸蓄电池不够绿色环保、投资效益较差等弊病一定程度上促成了各种新的替代供电技术的出现。针对模块化UPS、高压直流、DPS、飞轮UPS及动态UPS供电技术共五种新供电技术,重点从系统工作原理、实际应用模型、优劣和效益、建设投资等多个角度进行了深入的对比分析和研究,旨在为下一代绿色数据中心供电系统的规划建设提供决策依据。     

独立输入并联输出模块化DAB变换器功率均衡优化控制

针对独立输入并联输出IIOP(input independent output parallel)模块化双有源桥DAB(dual active bridge)变换器,当各模块的参数不匹配或输入电压不相等时的功率均衡问题,基于双重移相DPS(dual phase shift)控制,提出了一种功率补偿均衡控制PCEC(power compensation equalization control)算法以提高变换器的动态性能及其效率,并实现模块化DAB变换器的传输功率均衡。此外,考虑到大传输功率情况下,为实现各模块的充分运用,补充提出了一种功率补偿协同控制PCCC(power compensation cooperative control)算法。最后,基于DSP28335的半实物仿真平台对所提出的功率均衡方案进行对比实验验证。     

FPGA芯片内数字时钟管理器的设计与实现

在FPGA芯片内,数字时钟管理器(DCM)不可或缺,DCM主要完成去时钟偏移、频率综合和相位调整的功能,其分别由延迟锁相环(DLL)、数字频率合成器(DFS)以及数字相移器(DPS)三个模块来实现。对这三个模块的原理及设计进行了详细地阐述,并给出了仿真结果,该DCM电路通过了0.13μm工艺流片。测试结果表明,在低频模式下,该DCM能工作在24～230 MHz之间;在高频模式下,该DCM能工作在48～450 MHz之间,其输入及输出抖动容忍度在低频模式下能达到300 ps,在高频模式下能达到150 ps。     

Necessary and Sufficient Stability Criterion and New Forbidden Region for Load Impedance Specification

A necessary and sufficient impedance stability criterion for the DC Distributed power system （DPS） is proposed in small-signal sense, which has no conservativeness when compared with other stability criteria. This paper discusses the stability margin and gives it a definition for the round forbidden region. The reasons why the stability margin varies at different interfaces are also discussed in this paper. With the impedance stability criterion and stability margins considered, the sector forbidden region, which is a new forbidden region and can be easily calculated in the Bode diagram, is proposed to solve the calculation problem of the round forbidden region in engineering application. This paper also provides examples and simulations to verify the necessary and sufficient impedance stability criterion and the proposed sector forbidden region for the load impedance specification.     

安农S－1的温敏不育性在强感光性背景中的表达特性研究

为探讨水稻光敏不育性、温敏不育性及发育感光性之间的关系，将安农Ｓ－１的温敏不育性转入发育感光性强的农垦５８中，选择其后代的育性转换株（系）并进行发育和育性光温反应特性鉴定。结果表明：该组合中育性转换性不表现简单遗传，Ｆ２单株育性表现和分离比例复杂；温敏不育性能在发育感光性不同的遗传背景中表达，并获得了发育感光性强的温敏不育株；发育感光性强弱不改变温敏不育基因的基本特性，温敏不育性完全表达的临界温度高低亦与发育感光性无直接关系，而是受遗传背景的综合影响。     

平行结构类问题的分解与任务分布

本文给出平行结构类问题及其求解系统的形式化描述,讨论了此类问题的分解与任务分布,并提出了一种IPD算法(Improved Problem Decomposition).该算法从规模上将问题分解为若干性质相同的任务,按就近原则将任务预分布到系统中各结点上,并通过启发式状态空间查找方法进行负载调整,使系统负载平衡.试验表明:IPD算法的分解分布结果负载平衡,系统潜在协作量小.     

NUMERICAL SOLUTION TO SHAPE-CONTROL PROBLEMS OF WATER FLOW USING BEM-OPTIMIZATION METHOD

In this paper,some engineering problems arising from hydraulics and the design of hy-draulic structures are proposed,in accordance with the viewpoint of cybernetics,as the shape-controlproblems for distributed parameter system(DPS),whose solution is obtained using BEM-Optimizationtechnique.As a classical example,the problem of flow over a weir is converted first into a shape-con-trol problem,which is then converted into an optimization problem to be solved.Computational resultsshow that the BEM-Optimization method is an efficient way to solve shape-control problems for DPS,which not only can avoid the tedious process of trial and error or iteration,but also has high accuracyand less CPU consumption.For the problem of flow over a weir,the stream function,the free surfaceprofile and the unknown flow-rate can be found simultaneously.     

基于双有源桥DC/DC变换器回流功率优化的变频移相混合控制策略

分析了双重移相控制的双有源桥DC/DC变换器功率回流现象,并以减小回流功率为目标对双有源桥双重移相控制策略进行优化,推导出近似最优回流功率控制曲线。在此基础上,进一步提出了变频移相混合控制策略,使变换器控制参数在负载变化时保持在最佳工作点。最后,以理论推导为基础搭建了双有源桥实验平台,实验结果验证了所提方法对增加变换器效率的有效性。     

挠性板通孔电镀配方与工艺优化研究

为解决使用传统电镀液配方进行挠性板通孔电镀时出现的均镀能力(TP)差等问题,本文基于加速剂聚二硫二丙烷磺酸钠(SPS)、N,N-二甲基二硫代甲酰胺丙烷磺酸钠(DPS)的电化学性能测试,研究了整平剂对挠性板通孔电镀效果的影响,并对无整平剂的镀液体系中挠性板通孔电镀的影响因素进行了分析讨论。结果表明,SPS具有持续性的加速作用,是典型的加速剂,而DPS在高浓度条件下呈现出抑制效果,具有加速-整平双重特性;无整平剂体系下挠性板通孔的电镀效果(TP≥200%)明显要比有整平剂体系下的电镀效果(TP≈100%)要好,但是无整平剂条件下所得的铜镀层质量差;通过在无整平剂体系中加入DPS,利用DPS的微整平性能能够有效改善镀层质量。提高镀液中的铜离子浓度,降低酸的浓度、采用小电流密度、短时间电镀以及低气流量有利于提高通孔电镀的均镀能力。     

The Sequence of 32 kb on the Left Arm of Yeast Chromosome XII Reveals Six Known Genes,a New Member of the Seripauperins Family and a New ABC Transporter Homologous to the Human Multidrug Resistance Protein

The analysis of a 32 kb DNA fragment from cosmid 2G12 on the left arm of chromosome XII identifies 14 open reading frames (ORFs) numbered L0948 to L1325, a new tRNA for proline, a delta remnant and two putative ARS. Six ORFs have been previously identified: HSP104, SSA2, SPA2, KNS1, DPS1/APS and SDC25. Three putative ORFs have significant homology with known proteins: L0968 is a new member of the very large ‘seripauperins’ family, comprising at least 20 yeast members; L1313 is a new ABC transporter highly homologous to the yeast cadmium resistance protein Ycf1p and to the human multidrug resistance protein hMRP1; the C-terminal part of L1325 present in our sequence is very homologous to the fruit fly abdominal segment formation protein Pumilio. Finally, two ORFs, L1201 and L1205, have weak homology with two yeast hypothetical proteins of unknown function identified by the yeast systematic sequencing genome. Since our nucleotide sequence overlaps by 11·6 kb the cosmid 2B18 sequenced by Miosga and Zimmerman (1996) on the right end, we have not reported here the analysis of the ORFs L1313, L1321 and L1325. The complete nucleotide sequence of 32,088 bp and the deduced ORFs were submitted to the EMBL database under Accession Number X97560.© 1997 John Wiley & Sons, Ltd.