Hysteresis effect in floating-body partially depleted SOI CMOS domino circuits

This paper investigates in detail the basic mechanisms of hysteretic delay and noise margin variations for floating-body partially depleted SOI CMOS domino circuits. We first consider the ‘clock cycling scenario’, which completely eliminates (or isolates) the hysteresis effect of the output inverter, thus allowing one to observe and understand the hysteresis effect of the front-end domino logic stage. Three cases, based on whether the input signals are domino input signals, from other domino circuits, static input signals, from static circuits or latches; or a combination of domino and static input signals, are examined and differentiated. It is shown that hysteretic delay variation is the largest and the noise margin worst for the case with mixed domino and static input signals. Although the delay and noise margin disparities among the three types of input signals are significant at the beginning of the clock cycles, they converge as the circuit approaches steady state. The ‘data cycling scenario’ with the combined hysteresis effect of both the front-end domino logic stage and the output inverter is then discussed. Circuits operating under the ‘data cycling scenario’ are shown to have less body charge loss through the switching cycles than under the ‘clock cycling scenario’.     

Process/physics-based threshold voltage model for nano-scaled double-gate devices

Compact physics/process-based model for threshold voltage in double-gate devices is presented. Predominant short-channel effects for double-gate devices, which are drain-induced barrier lowering (DIBL) and short-channel-induced barrier lowering (SCIBL), are physically analysed and modeled to be applicable to SPICE-compatible circuit simulators. The short-channel models are also developed for bulk-Si device and compared to those of double-gate devices. The validity and predictability of the models are demonstrated and confirmed by numerical device simulation results for extremely scaled L _eff = 25?nm double-gate devices and bulk-Si device.     

Mobile Decentralized Search and Retrieval Using SMS and HTTP

Events over the past year have demonstrated the utility of mobile devices for coordinating mass gatherings and organizing protests in support of social change. However, governments have countered by censoring or disabling centralized search services and social networking sites. This paper describes a decentralized search and retrieval system, named iTrust, that provides resistance against the vulnerabilities of centralized services. It describes the iTrust with SMS interface and the iTrust SMS-HTTP bridge, which enable any SMS-capable mobile phone to communicate with and obtain information from HTTP nodes in the iTrust network. It also describes the iTrust over SMS protocol, which enables mobile phones to communicate directly with each other and share information in a peer-to-peer fashion bypassing the Internet. The paper also describes the Android user interface, which builds on the basic SMS capabilities of mobile phones and offers a user-friendly way of accessing the iTrust with SMS or iTrust over SMS implementation. Finally, the paper presents a performance evaluation of the iTrust search and retrieval system.     

气动加载与振动激励耦合试验方法研究

飞机结构在飞行过程中同时承受气动载荷和振动载荷的联合作用,这两种载荷的耦合加载试验对于飞机结构成为一项重要的研究内容,所以有必要对此类试验的可行性及其耦合加载方式进行研究。此次试验以气囊加载静载/常规疲劳载荷状态下试件的振动响应测试为目的,设计符合试验要求的试件和整套试验装置。得到了气囊5种不同加载情况下试件振动响应变化情况,并对此试验结果进行了理论分析,得出以下结论:a)气囊模拟静载/常规疲劳载荷加载不会大幅改变结构本身振动特性,此耦合试验方法所模拟环境比较接近飞机结构真实载荷环境;b)加载气囊的个数、部位及加载力的不同对试件结构的振动响应有一定影响,应增加气囊蓄能器或在试验前进行分析以选择合理的加载点。     

基于飞秒激光等离子体丝诱导击穿光谱探测土壤重金属Cr元素含量

本文基于飞秒激光等离子体丝诱导击穿光谱对土壤重金属Cr元素含量进行了实验研究.利用荧光法对等离子体丝的长度进行测量,给出了在不同焦距聚焦透镜作用下土壤中Cr425.5 nm的谱线强度空间分布,实验给出了Cr元素的定标曲线.实验结果表明,土壤中Cr元素浓度分析测量的相对标准偏差小于5%,土壤中重金属Cr元素的检测极限为7.85 ppm.表明飞秒激光等离子体丝诱导击穿光谱技术在土壤重金属Cr元素含量的定量探测方面是完全可行的.     

Efficient greyscale image compression technique based on vector quantization

In this paper, a novel greyscale image coding technique based on vector quantization (VQ) is proposed. In VQ, the reconstructed image quality is restricted by the codebook used in the image encoding/decoding procedures. To provide a better image quality using a fixed-sized codebook, the codebook expansion technique is introduced in the proposed technique. In addition, the block prediction technique and the relatively address technique are employed to cut down the required storage cost of the compressed codes. From the results, it is shown that the proposed technique adaptively provides better image quality at low bit rates than VQ.     

A first-principle study of the structural and electronic properties of amorphous Cu-Zr alloys

The atomic and electronic structures of amorphous CuxZr100-x(x=36,46,50,56,64) alloys were simulated using first-principle calculations within a 400-atom supercell.The pair correlation function,coordination numbers,local cluster structures and electronic density of states were analyzed.Reasonable agreements between the theory and the experiments were obtained.The amorphous alloys exhibit different local cluster structures and can all be explained with cluster formulas [cluster](glue)1,3,where the clusters a...     

Interfacial microstructure and bonding strength of Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.5Ce-xZn solder BGA packages with immersion Ag surface finish

Although it has been verified that tin whiskers can be prevented by the addition of 0.5 wt.% Zn into a Sn-3Ag-0.5Cu-0.5Ce solder, no detailed studies have been conducted on interfacial reactions and mechanical properties of Sn-3Ag-0.5Cu-0.5Ce-xZn solder joints with an immersion Ag surface finish. The intermetallic compounds formed during the reflow and aging of Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.5Ce-xZn solder ball grid array (BGA) packages were investigated. Because more heterogeneous nucleation sites, provided by CeSn₃ intermetallics and Zn atoms, formed in the Sn-3Ag-0.5Cu-0.5Ce-xZn solder matrix, and Cu and Zn have a stronger affinity than Cu and Sn, the Cu-Sn intermetallics growth in Sn-3Ag-0.5Cu-0.5Ce-xZn solder joints with Ag/Cu pads was suppressed. The 0.2% Zn addition for inhibiting rapid whisker growth in RE-doped Sn-Ag-Cu solder joints is more appropriate than 0.5 wt.% additions, as excess Zn addition causes poor oxidation resistance and inferior bonding strength.     

空腔膨胀理论靶体阻力模型及其应用研究进展

从静/动态空腔膨胀模型的理论体系出发,介绍了空腔膨胀模型在不同方向上取得的成果,主要涉及理想侵彻条件的空腔膨胀压力计算模型及数值模拟方法和空腔膨胀模型在典型侵彻问题及复杂弹靶条件下的应用。在理想侵彻条件下的空腔膨胀压力计算模型中,主要讨论了靶体材料、屈服准则和状态方程对空腔边界应力的影响规律及空腔膨胀模型的适用性问题;根据数值模拟中初始条件的不同,介绍了空腔表面恒定速度/恒定压力两种数值模拟方法,证明了数值模拟方法的可靠性;整理了空腔膨胀模型的基本假设、适用范围、工程应用特点,列举了其在典型侵彻问题及多层复合靶板、约束靶体、弹体刻槽和异形截面形状弹体等复杂弹靶条件下的应用。针对空腔膨胀模型的研究现状,总结了目前空腔膨胀模型在冲击动力学领域的应用方向,归纳了空腔膨胀模型应用中尚存在的问题,展望了空腔膨胀模型下一步的重点发展方向。