计算机网络远程通信系统软硬件设计与实现

本文介绍一种新型远程通信系统，它克服了一般远程通信系统速度慢的缺点，将通信速度提高了８０多倍，同时，其硬件比一般远程通信系统简单，成本只有一般远程通信系统的一半左右，进一步提高了新型远程通信系统的性能价格比。在新型系统中精简了远程通信协议，提高了信道有效利用率；采用了各种行之有效的数据压缩算法，并加以改造，使之性能最佳；提供了程序远程透明执行功能，大大提高了系统的响应速度。     

Characterization of zero locations of polytopes of real polynomials

Given a stability region of a polytope of polynomials, the edge theorem can be used to verify certain root-clustering properties of the polytope. The authors consider the inverse problem; starting with a polytope of real polynomials, they present a result that allows the construction of the smallest set of regions in the complex plane which characterizes its zero location     

Real-Time Quality Evaluation of Wire Bonding Using Input Impedance

Input impedance characterizes the dynamic property of a linear system. A few existing technologies thus exploit input electrical impedance of wire bonders as the signature to monitor ultrasonic wire bonding processes. However, the waveforms of "impedance" in these technologies are evaluated only approximately. To overcome the shortcoming, we propose a method to detect the true waveforms of both the real and imaginary part of the input impedance. In the method, the voltage and current at the input port of a wire bonder are probed and processed to obtain impedance via Hilbert Transform. Because dynamics of a bonding process represented by these waveforms is fully responsible for the resulted bonding quality, a quality evaluation system based on pattern recognition of these waveforms is further proposed. An artificial neural network using back propagation as training scheme learns from a set of training data to correlate a few features of the impedance waveforms with the bonding strength of the corresponding bond identified by shearing tests. Through a set of verification data, the built system is validated to be capable of evaluating bonding quality right after a bonding process. The proposed method is not only in situ and real-time, but also sensorless, which means that the system is easy to be implemented without interfering operation     

基于价电子理论的Ag-Sn金属间化合物形成机理

SnAgCu焊点中的金属间化合物(intermetallic compounds,IMCs)Ag3 Sn脆性大且电阻高,对焊点可靠性具有重要影响,有必要明确其形成过程和相变机制以控制其生长.采用固体与分子经验电子理论(empirical electron theory,EET)研究Ag-Sn系统中的主要扩散元素及原子运动路径,应用自洽键距差(self-consistent bond length difference,SCBLD)法计算了Ag-Sn系统内参与反应相的价电子结构及可能形成的固溶体的结合能,根据结合能变化趋势从价电子层面描述出Ag3 Sn在焊点内部的形成过程.研究结果表明:Ag-Sn系统中的主要扩散元素为Sn,Sn原子进入Ag晶胞形成固溶体,固溶体内原子重新排布,形成结合能更高、排布更均匀的共价键,造成晶格膨胀,位于(110)晶面和面心位置的Ag原子随之向外扩张,形成了同样具有良好对称性的Ag3 Sn,与前人研究Ag-Sn系统扩散的实验结果相符.     

Optimization and evaluation of reduced graphene oxide hydrogel composite as a demulsifier for heavy crude oil-in-water emulsion

The rising production of produced water from oilfields had been proven to bring detrimental environmental effects. In this study, an efficient, recyclable, and environmental-friendly reduced graphene oxide immobilized κ-Carrageenan hydrogel composite(κCa GO) was fabricated as an alternative sorbent for crude oil-in-water demulsification. Polyethyleneimine(PEI) was employed to form a stable hydrogel composite. The conditions for the immobilization of graphene oxide(GO) on PEI-modified κ-Carrageenan(κC) beads were optimized appropriately. An immobilization yield of 77% was attained at 2% PEI, 2 h immobilization activation time, and p H6.5. Moreover, the synthesized κCa GO is capable of demulsification with an average demulsification efficiency of 70%. It was found that the demulsification efficiency increases with salinity and κCa GO dosage, and it deteriorates under alkaline condition. These phenomena can be attributed to the interfacial interactions between κCa GO and the emulsion. Furthermore, the κCa GO can be recycled to use for up to six cycles without significant leaching and degradation. As such, the synthesized κCa GO could be further developed as a potential sorbent substitute for the separation of crude oil from produced water.     

A talking profile to distinguish identical twins

Identical twins pose a great challenge to face recognition due to high similarities in their appearances. Motivated by the psychological findings that facial motion contains identity signatures and the observation that twins may look alike but behave differently, we develop a talking profile to use the identity signatures in the facial motion to distinguish between identical twins. The talking profile for a subject is defined as a collection of multiple types of usual face motions from the video. Given two talking profiles, we compute the similarities of the same type of face motion in both profiles and then perform the classification based on those similarities. To compute the similarity of each type of face motion, we give higher weights to more abnormal motions which are assumed to carry more identity signature information.     

Analysis of two authorization protocols using Colored Petri Nets

To prevent unauthorized access to protected trusted platform module (TPM) objects, authorization protocols, such as the object-specific authorization protocol (OSAP), have been introduced by the trusted computing group (TCG). By using OSAP, processes trying to gain access to the protected TPM objects need to prove their knowledge of relevant authorization data before access to the objects can be granted. Chen and Ryan’s 2009 analysis has demonstrated OSAP’s authentication vulnerability in sessions with shared authorization data. They also proposed the Session Key Authorization Protocol (SKAP) with fewer stages as an alternative to OSAP. Chen and Ryan’s analysis of SKAP using ProVerif proves the authentication property. The purpose of this paper was to examine the usefulness of Colored Petri Nets (CPN) and CPN Tools for security analysis. Using OSAP and SKAP as case studies, we construct intruder and authentication property models in CPN. CPN Tools is used to verify the authentication property using a Dolev–Yao-based model. Verification of the authentication property in both models using the state space tool produces results consistent with those of Chen and Ryan.     

Robust Kalman filtering for uncertain discrete-time systems with probabilistic parameters bounded within a polytope

We consider the problem of finite horizon discrete-time Kalman filtering for systems with parametric uncertainties. Specifically, we consider unknown but deterministic uncertainties where the uncertain parameters are assumed to lie in a convex polyhedron with uniform probability density. The condition and a procedure for the construction of a suboptimal filter that minimizes an expected error covariance over-bound are derived.     

真空条件下辅酶Q_(10)的β-环糊精包合物的动力学模拟

首先通过分子力学法,确定辅酶Q10(CoQ10)的7个β-环糊精(β-CD)包合物(CoQ10-7-β-CDs)的最稳定优势构型.并进一步用分子动力学法模拟真空状态,一定时间内包合物的动态结构,并统计分析CoQ10包合前后结构的变化对性质的影响.结果表明CoQ10分子可以通过范德华力、库仑作用和氢键一起作用于β-CD分子形成1:7的稳定的D型包合结构.包合后,CoQ10分子的C=O双键和醌环上的C=C双键增长,侧链上的C=C双键缩短,其活性部位的抗氧化能力增大,而分子骨架的稳定性增强.     

SNORE: spike noise removal and detection

A method for detection and removal of random spike noise in magnetic resonance (MR) raw data (k-space data) is described. This method would reduce or eliminate the corduroy-type and higher than usual level artifacts in MR images resulting from random spike noise in k-space data. The method described involves applying a spatially varying threshold to be k-space data. Any data point that has a magnitude greater than that of the threshold value at that location will be replaced by a local complex average of the neighboring data points or some other suitable data replacement scheme.