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1.
“我有一个梦想:某一天三大运营商员工不摆摊了,不打架了,员工年收入差距缩小了,前端营业员待遇提高了,后端装维与资源矛盾化解了,服务质量提高了,恶性竞争消除了,重复建设停止了,不再破坏对手广告了,不互挖墙角搞策反了,不再零元购机了,不打价格战了,都能活的有尊严了”.  相似文献   

2.
    
江湖最近挺乱. 金融海啸了,经济危机了;奥巴马当选了,杨致远下课了;三聚氰胺走了又来了,"林书记"来了又走了;百度乱卖广告被央视曝光了,首富黄光裕涉嫌违法被拘查了;国家开始上万亿的花钱了,央行敢于一百零八个基点的降息了!  相似文献   

3.
Wedding……     
兄弟结婚了,朋友结婚了,朋友的朋友结婚了;男的结婚了,女的结婚了,不男不女的也结婚了;有感情的结婚了,没感情的结婚了,认识不认识的结婚已经无所谓了……  相似文献   

4.
《通信世界》2012,(26):6
"我有一个梦想:某一天三大运营商员工不摆摊了,不打架了,员工年收入差距缩小了,前端营业员待遇提高了,后端装维与资源矛盾化解了,服务质量提高了,恶性竞争消除了,重复建设  相似文献   

5.
本文提出了一种无需检测电感电流及其过零点的简单数字控制方案,实现了临界连续模式功率因数校正器的控制。取得了功率开关管的ZVZCS,消除了整流二极管和快恢复二极管的反向恢复带来的损耗,提高了变换器的效率和可靠性;另外,数字控制器克服了模拟IC控制器的开关频率限制问题,消除了输入电流的低频畸变,提高了功率因数;同时,也降低了输入电感的值,降低了成本的同时提高了功率密度。为实现中小功率数字控制功率因数校正器的产品化提供了一个良好的解决方案。  相似文献   

6.
在当今的社会中,人们已经离不开电子通信了,其作为了一个新兴产业,并得到了良好的应用,对各行各业起到了促进作用,同时,传统的产业收到了冲击。我国的电子通信发展较快,达到了先进的水平,不过,由于发展时间较短,存在很多不足之处,拉低了整体水平。特别是干扰问题,严重影响了电子通信的发展。本文对电子通信进行了概述,探讨了干扰要素,并且,提出了相关的应对策略。  相似文献   

7.
提出了一种紧靠热源制冷的IDC机房制冷解决方案。首先阐述了数据中心传统制冷解决方案,分析了其局限性,然后提出了冷源机柜的概念,分析了其原理及可行性,并进行了实际测试,最后进行了总结与展望。  相似文献   

8.
一种采用电容共用技术的DC-DC开关电源软启动电路   总被引:1,自引:0,他引:1       下载免费PDF全文
开关电源DC-DC转换器已经在各种电子设备中取得了广泛的应用。软启动电路保证了DC-DC转换器的正常启动,防止了器件的损坏。从理论上分析了软启动电路原理,设计了一种新型的开关电源软启动电路,该电路引入了电容共用方法,通过与频率补偿电容共用节省了软启动电容,降低了应用成本。并给出了具体电路实现,Spectre仿真结果验证了这种电路的可行性。  相似文献   

9.
介绍了大功率固态调制器电路常用的拓扑结构,讨论了开关直接串联与加法器叠加两种拓扑结构的特点.设计了基于绝缘栅双极性晶体管的加法器结构的大功率固态脉冲调制器,探讨了该类型大功率调制器的关键技术,介绍了调制器系统参数,并与国内外大功率调制器进行了对比.重点阐述了调制器实验,给出了实验结果,并对实验结果进行了分析.最后探讨了加法器结构的大功率固态脉冲调制器的优势及应用潜力.  相似文献   

10.
本文研究了供水系统运行状态实时模拟模型,首先对数据进行了预处理,然后运用多元线性回归,给出了准则判断了数据优势;建立了供水系统与用水量之间的数学模型,并给出了误差分析,探讨了供水量和用水量对模型的影响。  相似文献   

11.
双反应区激光制粉实验装置的研制   总被引:4,自引:0,他引:4  
提出了双反应区的新构思,研制出双反应区激光制粉实验装置。以5kW大功率CO2激光器为能源,以六甲基二硅胺烷为原料,对新装置进行了评价。结果表明,与单反应区实验装置相比,双反应区实验装置可成倍提高激光能的利用率和粉末的制备产率。  相似文献   

12.
激光与含能材料互作用的化学反应过程   总被引:8,自引:1,他引:8       下载免费PDF全文
沈瑞琪  孙同举 《激光技术》1997,21(4):191-195
反应性光声谱技术(RPAS)是近年来发展起来的一门新技术,它用于研究激光与物质互作用和快速的凝聚相化学反应。利用这一技术研究了激光与含能材料互作用的过程。研究发现并证实了脉冲激光激发下凝聚相的化学反应由光激发化学反应、慢速化学反应和快速加速的化学反应等三个阶段构成,反应性光声谱呈现出明显的双峰。  相似文献   

13.
建立了原子层沉积 (Atomic Layer Deposition,ALD)反应腔室的三维模型,利用ANSYS Fluent软件模拟分析了ALD过程中压强、前驱体脉冲时间、温度等工艺参数变化对前驱体分布的影响。模拟结果表明:反应压强越低,Mg(Cp)2前驱体分子的扩散系数越高,能更快且更均匀地分布在整个反应腔室之中;前驱体脉冲时间越长,在反应腔室内的分布越均匀;当脉冲时间为250ms时,Mg(Cp)2在反应腔室内分布基本均匀,反应腔室内各部位的前驱体质量分数基本一致;当脉冲时间为200ms时,H2O基本均匀分布在反应腔室内。在MgO薄膜的ALD温度窗口内,反应腔室内温度越高,Mg(Cp)2前驱体分子的扩散效应越强。  相似文献   

14.
文章主要介绍了pH对通过化学镀镍-磷法制作埋嵌电阻时镍-磷合金层方块电阻的影响。在温度相同的条件下,当镀液的pH不同时,探究了两种基材表面上镍-磷合金层方块电阻与反应时间的关系,并分析了适合用于制作埋嵌电阻的镍-磷合金层方块电阻值,以及最佳的化学镀镍-磷反应pH值。从实验结果可知,当反应时间相同时,随着pH的减小两种基材表面上镍-磷合金层的方块电阻将会逐渐大;适合用于埋嵌电阻制作的化学镀镍-磷反应pH为3.4~3.7,反应时间为3min~8min,方块电阻为15Ω/□~200Ω/□。  相似文献   

15.
文章以对三氟甲氧基溴苯和单乙二醇缩4,4'-双环己基二酮为起始原料,经格氏反应,脱水、氢化、脱保、转型、wittig反应、水解、转型和wittig反应,最终合成了液晶材料反-4-[反-4-(4-三氟甲氧基苯基)环己基]环己基-1-乙烯。其中脱水反应最佳溶剂选二甲苯,反应时间4h;氢化反应选Pd/C作催化剂;纯化后目标产物的纯度为99.5%(GC),总收率约为27.8%,其结构经IR、^1H NMR及MS确证。  相似文献   

16.
The effect of the anode and cathode on the electrochemical corrosion behavior of lead-free Sn-Ag-Cu and Sn-Ag-Cu-Bi solder joints in deionized water was investigated. Corrosion studies indicate that SnO crystals were generated on the surfaces of all lead-free solder joints. The constituents of the lead-free solder alloys, such as Ag, Cu, and Bi, did not affect the corrosion reaction significantly. In contrast to lead-free solders, PbO x was formed on the surface of the traditional 63Sn-37Pb solder joint in deionized water. A cathode, such as Au or Cu, was necessary for the electrochemical corrosion reaction of solders to occur. The corrosion reaction rate decreased with reduction of the cathode area. The formation mechanism of SnO crystals was essentially a galvanic cell reaction. The anodic reaction of Sn in the lead-free solder joints occurred through solvation by water molecules to form hydrated cations. In the cathodic reaction, oxygen dissolved in the deionized water captures electrons and is deoxidized to hydroxyl at the Au or Cu cathode. By diffusion, the anodic reaction product Sn2+ and the cathodic reaction product OH meet to form Sn(OH)2, some of which can dehydrate to form more stable SnO·xH2O crystals on the surface of the solder joints. In addition, thermodynamic analysis confirms that the Sn corrosion reaction could occur spontaneously.  相似文献   

17.
The volume effect in the reaction between Zn-doped solders and Cu is reported and explained in this article. Zn-doped solders with two different volumes, bulk solder baths (6 g) and small solder balls (10 mg), were reacted with Cu substrates. It was found that the reaction at the interface depended not only on the Zn concentration but also on the volume of the solder. For the bulk solder reaction the Zn concentration stayed nearly constant, whereas in the small solder joint case the Zn concentration changed substantially with the reaction time. This was because the Zn concentration during reaction was different for different solder volumes when the volume effect became important. For bulk solder baths, when the Zn content was 0.5 wt.%, the reaction product was a Cu6Sn5-based compound. As the Zn content increased to 2 wt.%, the reaction product switched to a Cu5Zn8-based compound. When the Zn content was 1.0 wt.%, Cu6Sn5 and CuZn formed simultaneously. When the solder volume became smaller, the Zn concentration was no longer constant, and the phase equilibrium at the interface changed with time. It was shown that the shifting of the equilibrium at the interface caused the massive spalling of CuZn.  相似文献   

18.
Yi He   《Microelectronics Reliability》2005,45(3-4):689-695
Curing kinetics of an epoxy-based underfill material with applications in flip chip ball grid array (FC-BGA) packages has been studied using differential scanning calorimetry (DSC). Non-isothermal DSC curves were obtained with heating rates ranging from 0.5 to 10 °C/min. Glass transition temperature as a function of fractional conversion was determined using temperature modulated DSC. Based on these experimental data, non-linear regression technique was used to evaluate the curing kinetics by considering both chemical- and diffusion-controlled reaction processes. As a result, it was determined that the curing reaction can be described by an nth order autocatalytic reaction partially controlled by diffusion, although the diffusion effect is relatively weak. The obtained optimized kinetic parameters allow us to predict the reaction behavior under various application conditions.  相似文献   

19.
讨论了几种数字滤波器算法.分析有限冲激响应滤波器和无限冲激响应滤波器各自的优点和缺点。提出一种利用可编程逻辑器件设计有限冲激响应滤波器的设计方法,并计算一个具体的有限冲激响应滤波器的参数。  相似文献   

20.
There is a lot ofhydroxyl on the surface ofnano SiO2 sol used as an abrasive in the chemical mechanical planarization (CMP) process, and the chemical reaction activity of the hydroxyl is very strong due to the nano effect. In addition to providing a mechanical polishing effect, SiO2 sol is also directly involved in the chemical reaction. The stability of SiO2 sol was characterized through particle size distribution, zeta potential, viscosity, surface charge and other parameters in order to ensure that the chemical reaction rate in the CMP process, and the surface state of the copper film after CMP was not affected by the SiO2 sol. Polarization curves and corrosion potential of different concentrations of SiO2 sol showed that trace SiO2 sol can effectively weaken the passivation film thickness. In other words, SiO2 sol accelerated the decomposition rate of passive film. It was confirmed that the SiO2 sol as reactant had been involved in the CMP process of copper film as reactant by the effect of trace SiO2 sol on the removal rate of copper film in the CMP process under different conditions. In the CMP process, a small amount of SiO2 sol can drastically alter the chemical reaction rate of the copper film, therefore, the possibility that Cu/SiO2 as a catalytic system catalytically accelerated the chemical reaction in the CMP process was proposed. According to the van't Hoff isotherm formula and the characteristics of a catalyst which only changes the chemical reaction rate without changing the total reaction standard Gibbs free energy, factors affecting the Cu/SiO2 catalytic reaction were derived from the decomposition rate of Cu (OH)2 and the pH value of the system, and then it was concluded that the CuSiO3 as intermediates of Cu/SiO2 catalytic reaction accelerated the chemical reaction rate in the CMP process. It was confirmed that the Cu/SiO2 catalytic system generated the intermediate of the catalytic reaction (CuSiO3) in the CMP process through the removal rate of copper film, infrared spectrum and AFM diagrams in different pH conditions. FinalLy it is concluded that the SiO2 sol used in the experiment possesses stable performance; in the CMP process it is directly involved in the chemical reaction by creating the intermediate of the catalytic reaction (CuSiO3) whose yield is proportional to the pH value, which accelerates the removal of copper film.  相似文献   

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