金属切削液在轴承加工中的应用

着重介绍金属切削液的分类、功能及其在轴承加工中的选用。在轴承加工中,一般有车削、铣削、钻削、铰削和磨削等多种加工工艺,其中磨削加工是一道非常重要的精密加工工序,如内圆磨削、外圆磨削、平面磨削和沟槽磨削等。轴承加工中使用的水基切削液不仅要具有冷却作用,还要有润滑、清洗和防锈的功能。重点介绍金属切削液的主要功能及其在轴承加工中的应用。     

Assessing the risk of “Kirkendall voiding” in Cu3Sn

A common location of sporadic, usually unpredictable, premature failures of both SnPb and Pb-free solder joints is within the intermetallic bond to one of the contact pads. Cu pads tend to be less prone to such defects than Ni/Au coated pads, but one phenomenon is a cause of growing concern for high reliability applications. Sporadic intermetallic problems are notoriously difficult to screen for, but at least a number of them are detectable right after assembly. However, the occasional formation of a network of voids within the Cu₃Sn layer forming when soldering to Cu pads is rarely noticeable until much later. To make matters worse, efforts to establish practical engineering tests for purposes of identification and screening have usually not been successful.The root cause of the so-called ‘Kirkendall voiding’ has been shown to be associated with the quality of the electroplated Cu, apparently as determined by the incorporation of minute amounts of specific organic impurities. The present work describes and discusses a series of potential tests that allow the sorting of electroplated Cu in terms of its propensity for Cu₃Sn voiding during soldering and subsequent aging. The times and efforts involved in these tests differ greatly, as do their effectiveness and accuracy. Individual tests may therefore be useful at various stages from supplier qualification to monitoring of batch to batch variations.     

预防为主 关口前移 二○一○年山东抗洪抢险取得全面胜利

2010年,山东省防汛形势复杂而严峻,极端天气事件频繁发生,人民群众生命财产安全受到极大威胁,部分地区遭受了较为严重的洪涝灾害,水利工程损坏严重。面对严峻的防汛形势,全省上下在省委、省政府的坚强领导下,扎实准备,主动防御,快速反应,科学防控,全力落实各项措施,确保了全省安全度汛,实现了无一水库垮坝、无一骨干河道决口、无一人因洪死亡的防控目标。     

奥氏体不锈钢TP321炉管焊缝铁素体含量控制实验分析

奥氏体不锈钢中铁素体含量既有有利的一面也有不利的影响,本文根据在实际工作中遇到具体的一种管材就此问题进行了分析和实验,对保证施工质量,防止炉管焊缝铁素体含量超标,有一定指导作用。     

超声振动辅助等离子沉积成形的研究

介绍了等离子沉积成形的原理、应用及其存在的优缺点,从超声原理出发介绍了超声振动对等离子沉积过程中晶粒及组织的影响,并设计了超声振动辅助等离子沉积成形的实验装置,对实验过程中以及该实验可能涉及的问题进行了探讨.     

Comparative study on internally heated and adiabatic regenerators in liquid desiccant air conditioning system

Liquid desiccant regeneration has important effect on performance of a liquid desiccant air conditioning system. Compared with conventional packed regenerator, internally heated regenerator is proposed to achieve better regeneration performance. This study emphasized on both regeneration rate and regeneration thermal efficiency to evaluate the performance of both regenerators. A validated heat and mass transfer model was used to analyse and compare the performance of internally heated and adiabatic regenerators. The results indicated that internally heated regenerator not only could increase the regenerate rate, but also could exhibit higher energy utilization efficiency. Different from adiabatic regenerator, internally heated regenerator can provide comparable regeneration efficiency and regeneration rate at low desiccant flow rate, so it should be a good alternative to avoid carryover of desiccant droplets. Higher air flow rate would result in a deduction of regeneration thermal efficiency although achieving higher regeneration rate. Suitable flow rate of the air should be considered carefully in liquid desiccant regeneration. The internally regenerator could have considerable prospect in liquid desiccant air conditioning application.     

绿色材料在家电中的应用研究

在节能环保、低碳循环技术发展的大趋势下,绿色材料的开发应用已成为家电业发展的主流方向之一。本文介绍了绿色材料的概念,阐述分析了生物基材料、无毒性材料、抑霉抗菌材料等绿色材料在家电领域的应用现状,探讨了家电用绿色材料的发展前景。     

Deterministic Sensing Matrices Based on Multidimensional Pseudo-Random Sequences

An approach is proposed for producing compressed sensing (CS) matrices via multidimensional pseudo-random sequences. The columns of these matrices are binary Gold code vectors where zeros are replaced by ?1. This technique is mainly applied to restore sub-Nyquist-sampled sparse signals, especially image reconstruction using block CS. First, for the specific requirements of message length and compression ratio, a set Λ which includes all preferred pairs of m-sequences is obtained by a searching algorithm. Then a sensing matrix A _M×N is produced by using structured hardware circuits. In order to better characterize the correlation between any two columns of A, the average coherence is defined and the restricted isometry property (RIP) condition is described accordingly. This RIP condition has strong adaptability to different sparse signals. The experimental results show that with constant values of N and M, the sparsity bound of A is higher than that of a random matrix. Also, the recovery probability may have a maximum increase of 20 % in a noisy environment.     

Transient Charging and Discharging Behaviors of Border Traps in the Dual-Layer HfO2/SiO2 High- κ Gate Stack Observed by Using Low-Frequency Charge Pumping Method

Transient charging and discharging of border traps in the dual-layer HfO₂/SiO₂ high-kappa gate stack have been extensively studied by the low-frequency charge pumping method with various input pulse waveforms. It has been demonstrated that the exchange of charge carriers mainly occurs through the direct tunneling between the Si conduction band states and border traps in the HfO₂ high-kappa dielectric within the transient charging and discharging stages in one pulse cycle. Moreover, the transient charging and discharging behaviors could be observed in the time scale of 10^-8- 10^-4 s and well described by the charge trapping/detrapping model with dispersive capture/emission time constants used in static positive bias stress. Finally, the frequency and voltage dependencies of the border trap area density could also be transformed into the spatial and energetic distribution of border traps as a smoothed 3-D mesh profiling