引线键合过程的动力学建模

以键合点对换能系统的相互作用为考虑的出发点,建立了有时变阻尼项的动力学模型来反映键合过程。通过Matlab数值仿真研究此模型的特性,并与实测数据对照,发现模型中加载项和粘性项的变化,可对应实际键合的特定阶段,由此证实该模型能够较合理地解释键合过程的强度形成规律,同时有助于对键合机理的研究和对工艺的监测与优化。

热超声键合PZT阻抗和功率动态特性研究

鉴于热超声芯片封装工艺的键合点空间高度局部化和时间瞬态性等特点,通过分析系统前端PZT阻抗和功率的动态变化规律,研究了芯片金球凸点与基板的键合过程及键合质量。结果表明:对于恒压源的键合系统,PZT换能器电流、阻抗及功率信号可表征键合过程的动态变化,且可将金球凸点与基板键合过程分为初始、平稳、结束三个阶段;键合环境的变化反映在PZT阻抗和功率变化之中,且PZT阻抗和功率与键合强度存在直接关系。试验及分析表明,PZT换能器阻抗和功率变化反映了金球凸点与基板键合过程及键合质量的差别,可用以分析整个键合系统。

铁路既有线桥涵基础及顶进施工关键技术方法分析

研究目的:通过分析查找改建既有线和增建第二线铁路桥涵基础及顶进桥涵施工中关系铁路行车和施工安全的关键过程、技术与方法。研究结论:改建既有线和增建第二线桥涵基础及顶进桥涵与管道工程施工安全风险较大,施工中必须高度重视,把握住关键过程,综合采用可靠、有效、成熟的施工技术与方法,卡死主要环节,把安全技术措施、组织措施落到实处,才能确保铁路行车和施工安全。

CMM2级需求管理在民办高校招生管理系统中的应用

生源是民办高校的生命线,民办高校招生管理成了学校发展的重中之重,为民办高校量身定做的招生管理系统屈指可数,结合民办高校招生管理实际情况,引进CMM2级需求管理在民办高校招生管理系统中的应用,真正做到招生过程的监管可控,决策有据可查,工作有章可循,提高工作效率。

Modulation classification of MPSK signals based on nonparametric Bayesian inference

A nonparametric Bayesian method is presented to classify the MPSK （M-ary phase shift keying） signals. The MPSK signals with unknown signal noise ratios （SNRs） are modeled as a Gaussian mixture model with unknown means and covariances in the constellation plane, and a clustering method is proposed to estimate the probability density of the MPSK signals. The method is based on the nonparametric Bayesian inference, which introduces the Dirichlet process as the prior probability of the mixture coefficient, and applies a normal inverse Wishart （NIW） distribution as the prior probability of the unknown mean and covariance. Then, according to the received signals, the parameters are adjusted by the Monte Carlo Markov chain （MCMC） random sampling algorithm. By iterations, the density estimation of the MPSK signals can be estimated. Simulation results show that the correct recognition ratio of 2/4/8PSK is greater than 95% under the condition that SNR 〉5 dB and 1 600 symbols are used in this method.

温度补偿压电基板

温度补偿压电基板是美国Ziptronix公司采用低成本压电材料(如LiTiO3和LiNbO3)与玻璃，石英或者其它低膨胀系数材料制成。基板的键合过程是在室温和室压下没有粘合剂和利用标准设备进行的，因而基板没有残留应力，材料位错极低和没有危害性废料。键合的基板是单一和均匀的材料，它的强度超过原料的断裂强度。

The AHP analysis on Quality Evaluation oriented to Bilingual Teaching Practices in Yunnan＇ s Universities

A number of studies show that bilingual education in private universities is worth studying in recent years, but its feasibility causes many debates at the same time which students are not as superior in both English proficiency and expertise as what we have expect- ed.However, it is undeniable that teaching process of teachers becomes significant influence on students＇ learning results. In my research I focus on the comprehensive view and procedures of teaching and set up the index system for evaluation of bilingual teaching process from teachers＇ perspective. In addition, I calculate the weighted value of each index at each level by using the root method, and determine the key success factors which affecting the quality of bilingual teaching process. Lastly, taking Oxbridge college as an example, I try to study what types of factors that constitutes conditions and limitations for a successful effect for bilingual teaching and to propose the solutions for improving and self-supervising in bilingual teaching process.

Key regions where land surface processes shape the East Asian climate

Land-atmosphere interaction,as one of the key processes affecting the atmosphere and climate over East Asia,has drawn increasing attention during the past few decades.However,the current level of understanding regarding the mechanisms through which land surface processes impact the East Asian climate needs to be improved.Based on existing studies,six key regions where land surface processes affect the East Asian climate are proposed in this study,which can provide a valuable reference for future research into land-atmosphere interaction in East Asia.

Reliability of gas holdup measurements using the differential pressure method in a cyclone-static micro-bubble flotation column

Gas holdup is one of the key parameters in flotation process. Gas holdup as measured by a differential pressure method was investigated and the relative errors compared to the average gas holdup from the volume expansion method. The errors were used to establish optimum measurement positions. The results show that the measurement position should be in the middle of the column and in the region half way from the center to the wall (the half-radius). The gas holdup along the axial direction is lower at the bottom and higher at the top of the floatation column. The gas holdup along the radial direction is lower near the wall and higher near the center of the flotation column. The average gas holdup measure- ment can be replaced by regional gas holdup values.

Fingerprint Identification by Artificial Neural Network

Biometric techniques require critical operations of digital processing for identification of individuals. In this context, this paper aims to develop a system for automatic processing of fingerprint identification by their minutiae using Artificial Neural Networks （ANN）, which reveals to be highly effective. The ANN method implemented is a based on Multi-Layer Perceptron （MLP） model, which utilizes the algorithm of retro-propagation of gradient during the learning process. In such a process, the mean square error generated represents the specific parameter for the identification phase by comparing a fingerprint taken from a crime scene with those of a reference database.

Selective Mono-Ozonolysis of a Cyclic 1,5,9-Cyclododecatrien

Some unsaturated compounds with the required （Z,Z）-double bonds configuration are synthesized through controlled ozonolysis process of 1,5,9-cyclododecatriene by determining the necessary amount of ozone passing through to selectively guarantee the breakage of a double bond while leaving other two bonds as （Z,Z）. The products were diagnosed by using NMR spectrum, infrared （IR） and mass spectrometer techniques. It is concluded that these products could widely be used in the synthesis of insect pheromones instead of insecticides and as useful intermediate compounds in many chemical reactions.

Entransy dissipation minimization for a class of one-way isothermal mass transfer processes

A class of one-way isothermal mass transfer processes with Fick’s diffusive mass transfer law[g ∝Δ(c)]is investigated in this paper.Based on the definition of the mass entransy,the entransy dissipation function which reflects the irreversibility of mass transfer ability loss is derived.The optimal concentration allocations of the key components corresponding to the highand low-concentration sides for the minimum entransy dissipation of the mass transfer process are obtained by applying opti- mal control theory and compared with the strategies of the minimum entropy generation,constant mass transfer flux(constant concentration difference),and constant concentration ratio(constant chemical potential difference).The results are as follows. For the optimal mass transfer strategy of the minimum entransy dissipation,the product of the square of the key component concentration difference between the high-and the low-concentration sides and the inert component concentration at the low-concentration side is a constant,while for that of the minimum entropy generation,the ratio of the square of the key com-ponent concentration difference between the high-and the low-concentration sides to the key component concentration at the low-concentration side is a constant;when the mass transfer process is not involved in energy conversion process,the optimi-zation principle should be the minimum entransy dissipation;the mass transfer strategy of constant concentration difference is superior to that of constant concentration ratio.The results obtained in this paper can provide some theoretical guidelines for optimal designs and operations of practical mass transfer processes.

Incubation time approach in rock fracture dynamics

The paper is summarizing latest results connected with application of the incubation time approach to problems of dynamic fracture of rock materials. Incubation time based fracture criteria for intact media and media with cracks are discussed. Available experimental data on high rate fracture of different rock materials and incubation time based fracture criteria are used in order to evaluate critical parameters of causing fracture in these materials. Previously discovered possibility to optimize (minimize) energy input for fracture is discussed in connection to industrial rock fracture processes. It is shown that optimal value of momentum associated with critical load in order to initialize fracture in rock media does strongly depend on the incubation time and the impact duration. Existence of optimal load shapes minimizing momentum for a single fracturing impact or a sequence of periodic fracturing impacts is demonstrated.

Surface-imprinted polymers in microfluidic devices

Molecularly imprinted polymers are generated by curing a cross-linked polymer in the presence of a template. During the curing process, noncovalent bonds form between the polymer and the template. The interaction sites for the noncovalent bonds become "frozen" in the cross-linking polymer and maintain their shape even after the template is removed. The resulting cavities reproduce the size and shape of the template and can selectively reincorporate the template when a mixture containing it flows over the imprinted surface. In the last few decades the field of molecular imprinting has evolved from being able to selectively capture only small molecules to dealing with all kinds of samples. Molecularly imprinted polymers (MIPs) have been generated for analytes as diverse as metal ions, drug molecules, environmental pollutants, proteins and viruses to entire cells. We review here the relatively new field of surface imprinting, which creates imprints of large, biologically relevant templates. The traditional bulk imprinting, where a template is simply added to a prepolymer before curing, cannot be applied if the analyte is too large to diffuse from the cured polymer. Special methods must be used to generate binding sites only on a surface. Those techniques have solved crucial problems in separation science as well as chemical and biochemical sensing. The implementation of imprinted polymers into microfluidic chips has greatly improved the applicability of microfluidics. We present the latest advances and different approaches of surface imprinting and their applications for microfluidic devices.