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Recently, the synchronous motion planning (SMP) has been viewed as a crucial issue in dual-arm robot systems. In this study, a new SMP scheme based on the Jacobian pseudoinverse formulation is presented and investigated for dual-arm robot systems. Such a scheme is established by discretizing the existing SMP scheme via a special difference formula. The presented discrete-time SMP (DTSMP) scheme is then theoretically analyzed to possess the biquadrate pattern in the end-effector planning error of each arm, thereby guaranteeing the synchronous planning precision of dual-arm robot systems. Simulation results under the system composed of two four-link planar robot arms are provided to further substantiate the effective and superior performance of the presented DTSMP scheme.

The switching capability required by data centers is rapidly developing, however, the technical limitations of the optical devices have created bottlenecks in their performance. Additionally, architectures that support thousands of servers remain to be explored. With a distributed control, we present a high-radix architecture that exploits the space domain and the wavelength domain to provide high throughput, achieving fast configuration and low latency. Considering the network size, we also propose two methods for implementation. We firstly form a strictly non-blocking network under the constraint of one connection per port. To scale up the switch, wavelength division multiplexing (WDM) is utilized to interconnect more servers and achieve higher bandwidth. The simulation results indicate that the proposed architecture can scale over thirty thousand servers with throughput reaching 87% while providing low latency.

Purpose. To assess the recognition pattern of dynamic action by visual prosthesis' wearers. Methods. Twenty volunteers (classified by gender and experience) were recruited to carried out action recognition test in simulated prosthetic vision. Twenty-three common dynamic actions video clips usually see in daily life were selected and formed the experimental action set which was divided into three parts including combined actions, simple actions and difficult actions in turn. The action animations made by 3D Studio Max were recorded by Banicam to convert to MP4 video format and processed to phosphene video clips by MATLAB in different resolutions (16 × 16, 24 × 24, 32 × 32, 48 × 48, 64 × 64, 128 × 128). Result. Comparing the recognition results, male group and female group had no significant difference. 48 × 48 resolution was the considerable latent capacity which subjects had stable performance. After a period of study, the performance of prosthesis wearers could be improved significantly.

The piston ring-cylinder liner friction pair is one of the most important friction pair in IC engines. In previous modelling studies, most researches were carried out based on a hypothesis that the inner surface of liner is an ideal cylindrical shell without considering the effects of dynamic deformation on oil film distribution. To investigate the potential influences of structural deformations on tribological behaviors of cylinder assemblies, the dynamic deformation of liner surface was obtained by FEM-based dynamic simulation, and then introduced into the lubrication model. Different from the traditional lubrication model where the pressure stress factor and shear stress factor are regarded as constant, this paper calculated these factors in real time by numerical integration to achieve more realistic simulation results. This study shows that the friction force obtained from the improved model manifests obvious fluctuations, and shows a significant reduction compared to original model.

Vibration of cylinder liners affects not only engine combustion performances but also tribological behaviour and noise radiations. However, it is difficult to characterize it experimentally due to multiple sources, strong background noise, and nonlinear transfer paths. Therefore, a finite element model is established in this study to predict the dynamic responses of cylinder liners under respective sources. The model takes into account both the characteristics of structural modes and nonlinearities of assembly constraints when selecting adequate elements for efficient computation of the responses under both the highly nonlinear combustion pressure excitations and subsequent piston slap impacts. The predictions are then evaluated against experimental results under different engine operating conditions. In addition, continuous wavelet analysis is employed to process the complicated responses for key response events and their frequency ranges. The results show agreeable correspondences between the numerical predictions and measured vibration signals, paving the way for investigating its effect on combustion and lubrication processes.

The friction between piston ring-cylinder liner is a major cause of energy losses in internal combustion engines. However, no experimental method is available to measure and analyze the fictional behavior. This paper focuses on the investigation of using acoustic emission (AE) to characterize the friction online. To separate the effect relating to friction sources, wavelets multi-resolution analysis is used to suppress interfering AE events due to valve impacts and combustion progress. Then a wavelet envelope indicator is developed to highlight AE contents from friction induced AE contents. The results show that the AE contents in the middle strokes correlate closely with viscous friction process as their amplitudes exhibit a continuous profile similar to piston speed. Furthermore, the AE envelope indicator proposed can distinguish the differences between two types of lubrication oils, showing superior performance of AE based online lubrication diagnosis.

This paper presents a novel method for diagnosing combination faults in planetary gearboxes. Vibration signals measured on the gearbox housing exhibit complicated characteristics because of multiple modulations of concurrent excitation sources, signal paths and noise. To separate these modulations accurately, a modulation signal bispectrum based sideband estimator (MSB-SE) developed recently is used to achieve a sparse representation for the complicated signal contents, which allows effective enhancement of various sidebands for accurate diagnostic information. Applying the proposed method to diagnose an industrial planetary gearbox which coexists both bearing faults and gear faults shows that the different severities of the faults can be separated reliably under different load conditions, confirming the superior performance of this MSB-SE based diagnosis scheme.

We illustrate capabilities of 3D integration for analog applications through both wafer-level and packaging technologies. Examples of wafer-level 3D integration include integrated capacitors and optical sensors. Integrated Si capacitors demonstrate the highest reported capacitor density of C=1 μF/mm2 (=1,000 fF/μm2) and the figure of merit (FOM) C*Vbd=11 C/m2 (Vbd is the breakdown voltage). Through-Si vias can be used to combine passive and active die into a single stack. Addition of optical layers to the Bipolar CMOS DMOS (BCD) process allows light detection in the visible and infrared range. 3D package-level integration is illustrated by embedding of multiple active and passive components in one package.

Condition monitoring of a gearbox is a very important activity because of the importance of gearboxes in power transmission in many industrial processes. Thus there has always been a constant pressure to improve measuring techniques and analytical tools for early detection of faults in gearboxes. This study forces on developing gearbox monitoring methods based on operating parameters which are available in machine control processes rather than using additional measurements such as vibration and acoustics used in many studies. To utilise these parameters for gearbox monitoring, this paper examines a model based approach in which a data model has been developed using a General Regression Neural Network (GRNN) to captures the nonlinear connections between the electrical current of driving motor and control parameters such as load settings and temperatures based on a two stage helical gearbox power transmission system. Using the model a direct comparison can be made between the measured and predicted values to find abnormal gearbox conditions of different gear tooth breakages based on a threshold setup in developing the model.

With the wide application of ERP system in Chinese manufacturing enterprise, information security problem becomes more and more important. Based on the discussion of the information security and the information risk, this paper systematically analyzed information security problems in the ERP conditions and targeted to bring the corresponding countermeasures and Suggestions.

The growth of laptops, personal digital assistant (PDA) and 802.11/Wi-Fi wireless networking have made mobile ad-hoc network (MANET) a popular research topic recently. Due to the flexible deployment nature and the lack of fixed infrastructure, MANETs suffer from varieties of security attacks. In this paper, we propose the misleading routing attack (MIRA), which is different from the well known gray/black hole attacks, in which a node is relaying the coming packets and not dropping them. MIRA attack aims to delay the packet as much as possible so as to let the source node time out before it receives the acknowledgment. Also it aims to overload the network by increasing the number of unexpected routing packets generated in the network. Our simulation results show that the existence of an adversary in the network launching a misleading routing attack will degrade packet transmissions in the network and increasing the number of lost packets as well as the retransmissions at the sender.

In this paper, we study the coordination of a decentralized supply chain in which a single manufacturer is selling a perishable product to a single retailer facing uncertain demand affected by her adverting expenditure and selling price and having shortage penalty. When the retailer behaving as a newsvendor faces stochastic advertisement and price sensitive demands, she has to make the advertising, pricing and ordering decisions before the demand is realized. We first establish the centralized model and prove that the supply chain can not be coordinated with the revenue sharing contract. We then show quantity discount contract can coordinate the supply chain and testify the special quantity discount contract can not coordinate our supply chain setting that was used in [8] to coordinate the newsvendor with demand dependent on price and effort. Finally, we prove the revenue and loss sharing contract presented in [12] coordinate the newsvendor with demand dependent on advertising expenditure also can not coordinate our supply chain setting and propose a contract called improved revenue and loss sharing contract which coordinates the decentralized supply chain.

The newsvendor problem is a fundamental building block for inventory management with a stochastic demand. The classic newsvendor problem focuses on maximizing the expected profit or minimizing the expected cost when she faces myopic customers. However, it ignores the customer's bargain-hunting behavior and risk preference measure of newsvendor. As a result, we carry out the rational expectation (RE) equilibrium analysis for risk-averse newsvendor facing forward-looking customers who anticipate future sales and choose purchasing timing to maximize their expected surplus. We propose the equilibrium price and quantity for the case where demand follows the uniform distribution and utility is power function. We identify the impact the system parameters on the RE equilibrium decisions for this specific situation.

Take the University Timetable Problem (UTP) as the research object, this paper divide the University Timetable Problem into two aspects: the determination of basic teaching tasks and the optimization of basic teaching time, Clarify the task of basic teaching methods and processes, Discusses in detail the steps of optimizing the basic teaching time based on genetic algorithm, Gives the algorithm of the fitness function, genetic crossover, variation and generation of initial population, and verified the value of the algorithm.

Road identification of anti-lock breaking system has an apparent effect to emergency brake and broad application prospects in the condition of high speed and low friction coefficient road or the complex road condition. In the controlling of anti-lock braking system all need to identify the road always accurate no matter what the basis of the wheel slipping ratio control nor the basis of the wheel speeded-up or slowed-down control. Because that different road surfaces have different anti-lock features and control parameters. For the sake of the application in the reality engineering and guarantee the accuracy of the identification results the purpose of this paper is against the large identification error of anti-lock breaking system road identification. Regard the vehicle and road as a complex nonlinear dynamic system and observe the randomness of the actual measured data and the effect of the system noise to identification. Use the normal distribution and weibull distribution in the statistical principles to road identification and use normal membership function to amend identification model. Tire model use the clear physical meaning theoretical model in order to increase the timeliness of the identification use simpson numerical integral and lagrange interpolation. The method this paper described is adopted largely in the road identification.

The fuel supply system of after-cooling diesel engine, D6114ZLQB, has been reformed based on the characteristic of D30(the ratio of DME/Diesel is 3/7). A series of emission tests have been processed under different fuel supply-advanced angles and injection starting pressures. The result shows: reduction of fuel supply-advanced angle has great influence on the emission of NOx, but little influence on PM; the emission of PM would increase and NOx decrease when reducing the fuel injecting pressure. During the whole speeds, CO and HC have not apparently changed.

This paper investigates the coordination of a decentralized supply chain in which a single manufacturer is selling a perishable product to a single retailer facing uncertain demand affected by her adverting expenditure and having shortage penalty. When the retailer behaving as a newsvendor faces stochastic advertisement-sensitive demands, she has to make the advertising and inventory decisions before the demand is realized. First, we establish that the supply chain can not be coordinated with the buy back, revenue sharing, and target rebate and quantity flexibility contract. Next, we show quantity discount contract can coordinate the supply chain and give a special quantity discount contract. Finally, we present a contract called revenue and loss sharing contract which mitigates the effect of shortage penalty loss and coordinates the decentralized supply chain.

This paper investigates the newsvendor model with advertise-setting. The retailer faces stochastic advertisement sensitive demands, she has to make the advertising and inventory decisions before the demand is realized. First, we establish the regular condition for the model and a sufficient condition under which the optimal advertising decision is no more than its risk-less counterpart. Next, we show how the optimal decisions change about the system parameters. Finally, we present an example to illustrate our findings. Our analysis generalizes the many known results in the literatures.

With considering lightening and safety of strength, integrations of both distribution's density and function's density, the normal fussy reliability formulas about vehicle parts that forces, strengths are gamma distribution and subordinate is parabola of exponential k was gotten; First integral change was achieved according to initial data and function imported and extent of integrated, second this number result with VB program in the computer was achieved by using middle-points integral calculus and romberg integration. This program can be used in design of vehicle parts for rising up level of design.

In the actual operating work of the concrete pump truck, there are many ill factors impact on the control quality that are environment interference, drive saturation, measurement error, rounding error and sampling delay. To overcome disadvantage, prove mathematical model accurate and identify parameters full, the group control was used; PSO algorithm was used to calculate the final value of every joint point, because the entire search is the process that updates the current optimal solution; all the particles are likely to faster convergence on the optimal solution; The PD control based on the gravity compensation for concrete pump truck boom was used, the advantage of control law are simple and easy to implement and can guarantee a good dynamic and static quality; In order to improve the joint operation real-time and accuracy, using cubic polynomial interpolation method described trajectory; Through the simulation examples analysis, the conclusion is that the method of combination PSO and gravity compensation is suitable for concrete pump truck boom control.

With considering lightening and safety of strength, integrations of both distributionpsilas density and functionpsilas density, the fuzzy reliability formulas about machine parts that forces are normal distribution, strengths are gamma distribution and subordinate is parabola of exponential k was gotten; First integral change was achieved according to initial data and function imported and extent of integrated, second the number result with VB program in the computer was achieved by using middle-points integral calculus and romberg integration. This program can be used in design of machine parts for rising up level of design.

To avoid it happening that the correctness of created model and developed simulation software on calculating the response time of ABS (anti-lock brake system) is partially verified by the experiment result, based on the structure of a typical ABS, the calculation models of the controllable characteristic and mechanical characteristic were created, and the simulation calculation software was developed. The current characteristic of the ABS is in real time detected on the computer simulation system, and the vehicular speed and the wheel speed were obtained. Especially, a Weibull similarity discriminate model of road surface was built. The model recognizes wheel speed data of theory and actual survey as the Weibull distribution while the first loop of anti-skid brake finish. When signals shape changed or noise interfered in the work, the model can classify and give right result. This model is benefit for batch produce, promote, renew and uphold of ABS.

To discriminate the quality on traditional Chinese medicines Zi-shen pill real-time, according to the characters of Zi-shen pill finger printer, the basic concepts of rough set are introduced briefly. For rough sets can only deal with discrete data, the discretization of data is the key factor in the rough sets applied in quality assessment, we present a method of discretization based on cluster category which combined with the characteristic of rough sets and back-propagation neural network, its generalization is well. Using methods rough sets and artificial neutral network to assess Zi-shen pill without any additional prior model assumption, rough sets data analysis can eliminate the redundancy of attributes and its value, identify the dependence in the attributes. We get a collective production rules about the chemical pattern classification system from sample data. When the model of chemical pattern classification is built by these rules, its meaning is very understandable in chemical domain, and the prediction of the model is also well.

To avoid it happening that the correctness of created model and developed simulation software on calculating the response time of ABS is partially verified by the experiment result, based on the structure of a typical ABS, the calculation models of the controllable characteristic and mechanical characteristic were created, and the simulation calculation software was developed. The current characteristic of the ABS is in real time detected on the computer simulation system, and the vehicular speed and the wheel speed were obtained. Especially, a gamma similarity discriminate model of road surface was built. The model recognizes wheel speed data of theory and actual survey as the gamma distribution while the first loop of anti-skid brake finish. When signals shape changed or noise interfered in the work, the model can classify and give right result. This model is benefit for batch produce, promote, renew and uphold of ABS.

With considering lightening and safety, integrations of both distributionpsilas density and functionpsilas density, a concept is given about conservative fuzzy reliability design of artificial limb rod. The conservative fuzzy reliability design formulas about artificial limb rod that load, destabilizing critical load, geometry dimension of component etc. are normal distribution and subordinate is parabola of exponential k was gotten; First, the integral change was achieved according to initial data and function imported and extent of integrated; second, the number result about the conservative fuzzy reliability design of artificial limb rod with VB program in the computer was achieved by using middle-points integral calculus and romberg integration. This program can be used in design of artificial limb rod for rising up level of design.

To discriminate the quality on traditional Chinese medicines RADIX NOTOGINSENG real-time, according to the characters of radix notoginseng finger printer, the basic concepts of rough set are introduced briefly. For rough sets can only deal with discrete data, the discretization of data is the key factor in the rough sets applied in quality assessment, we present a method of discretization based on cluster category which combined with the characteristic of rough sets and artificial neutral network, its generalization is well. Using methods rough sets and artificial neutral network to assess radix notoginseng without any additional prior model assumption, rough sets data analysis can eliminate the redundancy of attributes and its value, identify the dependence in the attributes. We get a collective production rules about the chemical pattern classification system from sample data. When the model of chemical pattern classification is built by these rules, its meaning is very understandable in chemical domain, and the prediction of the model is also well.

The classic newsvendor problem is to make a single - period procurement decision of a single product under stochastic demands. The newsvendor problem with advertising decision provides an important means to examine how operational problems interacts with marketing issues to influence decision-making at the firm level. When a newsvendor faces stochastic advertisement-sensitive demands, he has to make the advertising and inventory decisions before the demand is realized. In this paper, we investigate the case in which advertising leads to in creasing in sales under stochastic additive demand. We assume the mean demand is strictly increasing and strictly concave in advertising premium and explore: (1) the optimal solution's properties and (2) the comparative statics of parameter changes.

To avoid it happening that the correctness of created model and developed simulation software on calculating the response time of ABS is partially verified by the experiment result, based on the structure of a typical ABS, the calculation models of the controllable characteristic and mechanical characteristic were created, and the simulation calculation software was developed. The current characteristic of the ABS is in real time detected on the computer simulation system, and the vehicular speed and the wheel speed were obtained. Especially, a normal similarity discriminate model of road surface was built. The model recognizes wheel speed data of theory and actual survey as the normal distribution while the first loop of anti-skid brake finish. When signals shape changed or noise interfered in the work, the model can classify and give right result. This model is benefit for batch produce, promote, renew and uphold of ABS.

To the traditional bioequivalent identification, the stringent requirements, limitations on the scope of inspection and the enormous waste of inspection resources are analyzed. The bioequivalent model of normal distribution is established perfectly by using statistical theory; the normal model of tested system about medium-sized samples is established by using information entropy method of no-statistics theory, the normal model of tested system about small-sized samples is established by using Bayesian method of no-statistics theory. In order to achieve the unified identification algorithm, the equivalent normal transforms of information distribution is quoted; all models are established and are calculated through VB Programming; Through analysis of the examples about traditional and normal method, we know that two bioequivalent identification methods is identity, but normal method is more simple, intuitive and easy to grasp than traditional method. The normal bioequivalent method can suit to broad and complex bioequivalence test, save various testing resources, reduce testing costs.

To avoid it happening that the correctness of created model and developed simulation software on calculating the response time of ABS is partially verified by the experiment result, based on the structure of a typical ABS, the calculation models of the controllable characteristic and mechanical characteristic were created, and the simulation calculation software was developed. The current characteristic of the ABS is in real time detected on the computer simulation system, and the vehicular speed and the wheel speed were obtained. Especially, a lognormal similarity discriminate model of road surface was built. The model recognizes wheel speed data of theory and actual survey as the lognormal distribution while the first loop of anti-skid brake finish. When signals shape changed or noise interfered in the work, the model can classify and give right result. This model is benefit for batch produce, promote, renew and uphold of ABS.

In view of importance of teaching quality evaluation, the process and results are fully concentrated on considering entirety and dynamics. A method of teaching quality evaluation calculation is proposed on the basis of Bayes analysis and implemented by way of VB program. The no-strictness and no-accuracy results of conventional calculating methods are analyzed. Discusses how to calculate the standard difference in Bayes analysis, how to evaluate teaching quality through similar of normal distribution, how to program procedures. Conclusion: the method proposed is available to get rid of the harsh request of large sample data and make the results more accurate; The character of procedures compiled are security, compatibility and transplantation, suitable for the needs of practical work.

In view of importance of teaching quality evaluation, the process and results are fully concentrated on considering entirety and dynamics. A method of teaching quality evaluation calculation is proposed on the basis of information entropy and implemented by way of VB program. The no-strictness and no-accuracy results of conventional calculating methods are analyzed. Discusses how to calculate the standard difference in information entropy, how to evaluate teaching quality through similar of normal distribution, how to transform equivalently other distributions to normal distribution.The method proposed is available to get rid of the harsh request of large sample data and make the results more accurate; it has a wide range of universal that translate lognormal distribution of standard system to equal normal distribution; The character of procedures compiled are security, compatibility and transplantation, suitable for the needs of practical work.

With considering lightening and safety of strength, integrations of both distributionpsilas density and functionpsilas density, the normal fuzzy reliability formulas about robot parts that forces are normal distribution, strengths are Weibull distribution and subordinate is gamma function was gotten; first integral change was achieved according to initial data and function imported and extent of integrated, second the number result with VB program in the computer was achieved by using middle-points integral calculus and romberg integration. This program can be used in design of robot parts for rising up level of design.

To discriminate the quality on traditional Chinese medicines Eucommia Bark real-time, according to the characters of Eucommia Bark finger printer, the basic concepts of rough set are introduced briefly. For rough sets can only deal with discrete data, the discretization of data is the key factor in the rough sets applied in quality assessment, we present a method of discretization based on cluster category which combined with the characteristic of rough sets and perceptron, its generalization is well. Using methods rough sets and artificial neutral network to assess Eucommia Bark without any additional prior model assumption, rough sets data analysis can eliminate the redundancy of attributes and its value, identify the dependence in the attributes. We get a collective production rules about the chemical pattern classification system from sample data. When the model of chemical pattern classification is built by these rules, its meaning is very understandable in chemical domain, and the prediction of the model is also well.

In view of importance of teaching quality evaluation, the process and results are fully concentrated on considering entirety and dynamics. A method of teaching quality evaluation calculation is proposed on the basis of grey relation analysis and implemented by way of VB program. The no-strictness and no-accuracy results of conventional calculating methods are analyzed. Discusses how to calculate the standard difference in grey relation analysis, how to evaluate teaching quality through similar of normal distribution, how to program procedures. Conclusion: the method proposed is available to get rid of the harsh request of large sample data and make the results more accurate; The character of procedures compiled are security, compatibility and transplantation, suitable for the needs of practical work.

Network motifs have been demonstrated to be the building blocks in many biological networks such as transcriptional regulatory networks. Finding network motifs plays a key role in understanding system level functions and design principles of molecular interactions. In this paper, we present a novel definition of the neighborhood of a node. Based on this concept, we formally define and present an effective algorithm for finding network motifs. The method seeks a neighborhood assignment for each node such that the induced neighborhoods are partitioned with no overlap. We then present a parallel algorithm to find network motifs using a parallel cluster. The algorithm is applied on an E. coli transcriptional regulatory network to find motifs with size up to six. Compared with previous algorithms, our algorithm performs better in terms of running time and precision. Based on the motifs that are found in the network, we further analyze the topology and coverage of the motifs. The results suggest that a small number of key motifs can form the motifs of a bigger size. Also, some motifs exhibit a correlation with complex functions. This study presents a framework for detecting the most significant recurring subgraph patterns in transcriptional regulatory networks.

Pillar bump is a novel interconnect structure, including non-reflowable base and a reflowable cap like a pillar shape. In this study, pillar bump with copper base and Sn63/Pb37 eutectic solder cap is processed via electrolytic plating. Based on whether flat eutectic cap is reflowed prior to assembly, pillar bump is further split into two categories, namely pre-reflowed and non-reflowed, respectively. Assembly feasibility assessment as well as bump integrity evaluation are carried out. Bump shear test is conducted for both before and after reliability and failure mode is characterized via SEM and EDX. Furthermore, a 10 mm/spl times/10 mm test chip having 180 Cu/eutectic solder pillar bumps with 0.2 mm pitch is assembled onto BT substrate via no clean flux and subsequently underfilled. The results show that pillar shape is still maintained after assembly that can meet fine pitch requirement. No shear strength deterioration after moisture sensitivity preconditioning and 1000 thermal cycle test (TCT, -40/spl deg/C/spl sim/125/spl deg/C) has been observed. EDX spectra indicate fracture has occurred in the interfacial region between Al and silicon, not arising from bumping process. Furthermore, bump integrity is intact after package level reliability test under the same conditions as above. Stress simulation results lead to conclusion that maximum shear stress occurs in copper pillar portion with average range of 40/spl sim/50 MPa that is much below the shear strength of copper.

In this study, Sn/Ag/Cu Pb-free solder paste was printed and reflowed onto a thin film Al/Ni(V)/Cu under bump metallization (UBM) on a 4mm /spl times/ 5mm die and, packaged in a 5mm /spl times/ 6mm LGA (land grid array) package using four different underfill materials with a range of different material properties. The packages were then examined after 1, 3 and 6 reflow cycles in addition to various standard package reliability tests. Package level Finite Element Analysis (FEA) was also conducted to simulate the solder creep strain under various strain rates of temperature cycling (TC) or thermal shock (TS) at. In addition, SEM and concurrent Elementary Mapping were used to characterize the integrity of the UBM. The FEA results show that underfill materials with a high Tg and a low coefficient of thermal expansion (CTE) could substantially minimize the solder's maximum equivalent creep strain under cyclical stress excursions. This conclusion was in agreement with actual package level reliability results. By selecting the appropriate underfill properties, this Pb-free flip chip package has passed moisture sensitivity level (MSL-3) with 3 reflow cycles at peak temperature of 260/spl deg/C, followed by TC 1500 cycles, low temperature thermal shock (LTS) 800 /spl times/ and unbiased highly accelerated stress test (UHAST) 168h. Additional observations noted include that the Cu was nearly completely consumed after these package assembly reflows. It was also found that Ni diffused into bulk solder after the aforementioned multiple reflow cycles.

It is of the most important problems in the finance investment field that how to choose a satisfactory portfolio causes the most efficient risk-return match. Because the different scholars research the risk from the different views so they understand the risk differently. This paper introduces the concept of the worst-case VaR in the double objective portfolio model and considers the expected returns and the fuzzy of risk and discusses the logistic membership function model. This paper regards the maximization of portfolio return and the minimization of worst-case VaR as its goal and sets up a new portfolio decision-making model based on the fuzzy multiple objective programming. The author uses the genetic algorithm to do the simulated computation and validates the efficiency of the model according to 8-stock return data of Shanghai security.

This paper presents two flip-chip assembly processes that enable an underfill with higher filler loading to be incorporated into the package. The first process includes dispensing the underfill containing higher filler loading on substrate surface, followed by chip placement and solder reflow under thermal compression. Apart from this, the second approach is virtually the modification of standard reflowable underfill process. The underfill with higher filler loading was spin-coated onto a bumped wafer surface and then cured. Subsequently, the top portion of bumps was exposed by laser treatment prior to wafer dicing. The diced chips with low CTE coating on the surface already were assembled via standard reflowable underfill process that includes dispensing reflowable underfill, chip placement and solder reflow through reflow oven.

This paper presents process concerns of flip-chip assembly via reflowable underfill in terms of substrate prebake, underfill dispensing, chip placement and overmolding that is required in certain applications. Test vehicles with various chip configurations and substrate design have been used in this study. The effects of substrate thickness, bond pad design and solder mask thickness on assembly defects, where void is the major contribution, were extensively elucidated. Meanwhile, approaches to solve the assembly failure have been successfully demonstrated by means of fine-tuning assembly parameters. It was found that voids were mainly from trapped air-bubbles during assembly, where underfill dispensing and chip placement are the major sources, rather than from reflowable underfill outgassing during reflow. The trapped voids could become aggravated after solder reflow process. In addition, pad design and solder mask thickness also significantly affect the void level. This study unveils that substrate bond pad with pre-solder on the surface traps less void than those only with nickel gold finish. For the latter case, substrate heating during underfill dispensing enables to enhance underfill flow and in turn reduces void. Furthermore, die heating that can be implemented via bonding head with heating element during chip placement will dramatically reduce void as well. Discussion will also be given on the impact of solder mask thickness and chip placement; speed (search speed) on void, in particularly for non pre-solder capped substrate.

This paper presents the material properties, assembly process identification and reliability performance coupled with failure analysis of a newly developed reflowable underfill. The curing profile, glass transition temperature (Tg), coefficient of thermal expansion (CTE) and modules were investigated via differential scanning calorimeter (DSC), thermo-mechanical analyzer (TMA) and dynamic mechanical analyzer (DMA), respectively. The dependence of viscosity on aging time was measured via Brookfield viscometer. Wettability was demonstrated through solder sphere wetting test. In addition, the effect of reflow profile on wettability was evaluated as well, for example, the variation of overall acid number under several reflow profiles was monitored via titration with standard sodium hydroxide (NaOH) solution. After that, approaches to control voids were made by manipulating material aging time and adjusting reflow profile, and the effects were subsequently identified via scanning acoustic microscopy (C-SAM).