多线切割机磨削热的不良影响及消除

介绍了多线切割机磨削热的危害性,提出了磨削热的具体消除方法。     

金丝球焊机金丝检测技术

在应用于三极管压焊的全自动金丝球焊机中,金丝检测是确保压焊过程工艺质量的关键技术。通过设计金丝的打火失球检测和第一焊点、第二焊点压焊失败检测电路,实现金丝球焊机的金丝压焊效果自动检测功能。实验证明,所设计的检测电路完全满足压焊工艺质量的要求。     

大功率广播发射机的地线干扰与抑制

分析了地线干扰产生的原因,对地电流和地电压的形成进行了阐释,结合大功率广播发射机发生的地线干扰故障实例,阐述了地线干拢的抑制措施。     

GSM网络优化中KPI指标优化问题的分析

网络优化是在分析网络状况基础上,对系统参数和网络设备做出调整,从而使网络达到最佳运行状态.本文从网络统计指标优化入手,通过分析GSM网络掉话率、切换成功率等KPI指标的优化过程,得到引起网络掉话现象的原因和导致切换失败的因素.最后结合GSM网络具体优化案例,进一步分析并验证KPI指标的优化对整个网络性能的影响.     

电子及杂质离子-LO声子耦合对柱形量子线中杂质态的影响

采用有效质量近似和变分方法,同时考虑电子-约束型体纵光学声子(LO)及杂质离子-LO声子耦合,计算了有限深柱形量子线中杂质的极化效应。计算得到杂质结合能及声子贡献随量子线半径的关系。结果表明由电子-LO声子相互作用引发的极化效应的行为与杂质离子-LO声子相互作用引起的屏蔽效应相反,两种效应最终使杂质的结合能降低。     

钢丝绳捻制成形接触问题的有限元分析

基于虚功原理建立了钢丝绳捻制成形过程中考虑接触摩擦时的刚度方程,将小球分裂算法用于接触搜索,Augmented Lagrange法用于计算接触力．以钢丝绳一次捻制成形过程为例,分析了摩擦系数和自扭转系数对接触应力和加工应力域变的影响．研究结果表明。摩擦系数对剪应力的影响比对等效应力和等效塑性应变的影响大;考虑摩擦时钢线表面的轴向残余应力计算结果比无摩擦条件下的计算结果更接近实验结果．     

基于不同结构新型方形超导线材的交流损耗仿真研究

高温超导体的交流损耗直接影响超导设备的价格及其商用化.对于高温超导体,降低其交流损耗有助于优化电力传输性能并降低运行成本.对于不同堆叠结构的YBCO超导方形线材,本文使用有限元分析软件Comsol Multiphysics基于H方程计算了不同种类方形线材的交流损耗.通过数据汇总计算与结果分析,验证了仿真计算的有效性、准确性与合理性.     

An in‐needle solid‐phase microextraction device packed with etched steel wires for polycyclic aromatic hydrocarbons enrichment in water samples

A novel, low‐cost and effective in‐needle solid‐phase microextraction device was developed for the enrichment of trace polycyclic aromatic hydrocarbons in water samples. The in‐needle solid‐phase microextraction device could be easily assembled by inserting hydrofluoric acid‐etched wires, which were used as adsorbent, into a 22‐gauge needle tube within spring supporters. Compared with the commercial solid‐phase microextraction fiber, the developed device has higher efficiency for the extraction of polycyclic aromatic hydrocarbons with four to six rings from water samples using the optimized extraction conditions. With gas chromatography equipped with a flame ionization detector, the limits of detection for the polycyclic aromatic hydrocarbons with four to six rings ranged from 0.0020 to 0.0067 ng/mL. The relative standard deviations for one needle and needle‐to‐needle extractions were in the range of 5.2–9.9% (n = 5) and 3.4–12.3% (n = 5), respectively. The spiked recoveries of the polycyclic aromatic hydrocarbons in tap water samples ranged from 73.2 to 95.4%. This in‐needle solid‐phase microextraction device could be a good field sampler because of the low sample loss over a long storage time.     

Evaluation of dsDNA as a wire for redox-active proteins

The redox-active multiligand-binding flavoprotein dodecin binds flavins with high affinity when they are oxidized, whereas flavin reduction induces the dissociation of the holoprotein complex in apododecin and free flavin ligands. Dodecin could be reconstituted at flavin-terminated dsDNA monolayers. The binding and release of apododecin triggered by the redox state of the flavins can be monitored by surface-sensitive techniques such as surface plasmon resonance and quartz crystal microbalance measurements with dissipation monitoring. It has been shown that flavin reduction followed by the release of apododecin can be achieved by mediated electron transfer in the presence of the redox mediator amino ethyl viologen and by chemical flavin reduction, whereas flavin reduction by direct electron transfer via the dsDNA tethers is not possible. The combination of electrochemistry with surface-sensitive techniques such as surface plasmon resonance or quartz crystal microbalance measurements with dissipation monitoring could be highly beneficial to confirm or disprove the mechanism, which has been postulated for the action of primases, which contain a [4Fe4S] cluster and are involved in DNA replication. It has been postulated that these enzymes bind the DNA template when the cluster is in the [4Fe4S]³⁺ state, whereas they are released when the cluster is reduced via electron transfer through DNA and the protein environment.     

圆柱状量子点量子导线复合系统的激子能量和电子概率分布

建立了圆柱状量子点量子导线复合系统中激子满足的方程，用微扰论求出激子能量.以CdS/HgS/CdS/HgS/CdS圆柱状量子点量子导线复合系统为例，研究了系统中电子的概率分布和系统线度对激子能量的影响.结果表明：系统中电子、空穴以及激子的能量均随量子点高度h₀的增大而减小，电子-空穴相互作用对基态激子能量的影响要大于激发态；电子沿径向方向的概率分布呈起伏状，在轴线和表面附近的概率趋于零，而在R/2附近概率最大；在量子点附近电子沿轴向方向的概率分布呈振荡特征 关键词： 量子点 量子导线 激子 能量