高聚物注塑成型的可模性研究

根据Holmes理论公式,研制出阿基米德螺旋线凹槽模具。在注塑成型工艺条件下,测定低密度聚乙烯(LDPE)和聚丙烯(PP)的可模性。实验表明:自行研制的阿基米德螺旋线凹槽模具可以迅速而准确地测定出高聚物的可模性,不同种类高聚物和不同工艺条件下高聚物的可模性不同。

APPLICATION OF MECHANICAL RELIABILITY PREDICATION BASED ON FUZZY THEORY

Mechanical reliability prediction (MRP) is an important task of mechanical reliability design. In the initial design stage (IDS), the lack of reliability data and some fuzzy characteristics of MRP make this work hardness. Because fuzzy synthetical assessment (FSA) can well utilize expert′s experience and fuzzy data, it is used to assess the influence factors of reliability. On the basis of the assessed results, the predicted value of reliability is inferred by the fuzzy inference system (FIS). This approach particularly suits to predict the reliability of complex machinery (including other products) in IDS, so that it can remedy some defects of the existing methods. An example is discussed to interpret how to utilize it.

Product reliability assessment based on proportional hazard degradation model

In order to evaluate the reliability of long-lifetime products with degradation data, a new proportional hazard degradation model is proposed. By the similarity between time-degradation data and stress-accelerated lifetime, and the failure rate function of degradation data which is assumed to be proportional to the time covariate, the reliability assessment based on a proportional hazard degradation model is realized. The least squares method is used to estimate the model＇s parameters. Based on the failure rate of the degradation data and the proportion function of the known time, the failure rate and the reliability function under the given time and the predetermined failure threshold can be extrapolated. A long life GaAs laser is selected as a case study and its reliability is evaluated. The results show that the proposed method can accurately describe the degradation process and it is effective for the reliability assessment of long lifetime products.

Material driven workability simulation by FEM including 3D processing maps for magnesium alloy

The three-dimensional （3D） processing maps considering strain based on the two-dimensional （2D） processing maps proposed by PRASAD can describe the distribution of the efficiency of power dissipation and flow instability regions at various temperatures, strain rates and strains, which exhibit intrinsic workability related to material itself. Finite element （FE） simulation can obtain the distribution of strain, strain rate, temperature and die filling status, which indicates state-of-stress （SOS） workability decided by die shape and different processing conditions. On the basis of this, a new material driven analysis method for hot deformation was put forward by the combination of FE simulation with 3D processing maps, which can demonstrate material workability of the entire hot deformation process including SOS workability and intrinsic workability. The hot forging process for hard-to-work metal magnesium alloy was studied, and the 3D thermomechanical FE simulation including 3D processing maps of complex hot forging spur bevel gear was first conducted. The hot forging experiments were carried out. The results show that the new method is reasonable and suitable to determine the aoorooriate nrocess narameters.

ALLIED FUZZY c-MEANS CLUSTERING MODEL

A novel model of fuzzy clustering, i.e. an allied fuzzy c means （AFCM） model is proposed based on the combination of advantages of fuzzy c means （FCM） and possibilistic c means （PCM） clustering. PCM is sensitive to initializations and often generates coincident clusters. AFCM overcomes this shortcoming and it is an ex tension of PCM. Membership and typicality values can be simultaneously produced in AFCM. Experimental re- suits show that noise data can be well processed, coincident clusters are avoided and clustering accuracy is better.

Effect of Different Fertilization Patterns on Carbon and Nitrogen Components of Tobacco Topsoil

In order to explore the fertilizing ways and dynamic changes of soil carbon and nitrogen in the main producing areas of tobacco in Guizhou,research was conducted to study the variations of dissolved organic carbon and nitrogen,total organic carbon and nitrogen and their ratio of tobacco-topsoil in organic fertilization pattern and conventional cultivation pattern （No fertilizer as control） by pot experiment.The results were as follows：（1） The effects of different fertilization patterns on soil dissolved organic carbon and nitrogen and total organic carbon and nitrogen were significantly different.The content of DOC,DON,TOC and TON in tobaccotopsoil was decreased with the advancing of growth period in conventional fertilization pattern.In the conventional fertilization pattern,the accumulation of DOC and TOC was increased first and then decreased,and the accumulation of DON and TON was decreased first and then increased.（2） The TOC content at the different growing stage and DOC content at the middle and later stage of tobacco were significantly improved in organic fertilization patterns.The accumulation of DON and TON in the conventional fertilization pattern was significantly higher than those in the organic fertilizer pattern and control at the rosette stage and vigorous stage.In the harvest period,the content of DOC,DON,TOC and TON of tobacco-topsoil in the conventional fertilization and organic fertilization pattern was significantly higher than those in the control.（3）The DOC/DON ratio and the TOC/TiON ratio was increased gradually with the advancing of growth period in conventional fertilization pattern,but they were increased first and then decreased in the organic fertilization pattern and CK.The DOC/DON and TOC/TON ratio of tobacco-topsoil in different fertilization patterns was showed as Y J＞ CK＞ CG at the different growing stage.The experiment results revealed that：The organic fertilization pattern may improve significantly the accumulation of DOC,DON,TOC and TON of tobacco-topsoil at the middle and later stage and the DOC/DON and TOC/TON ratio at the different growth stage.It contributed to the continuous and balanced supply of nutrients at the middle and later stage of tobacco and the soil fertility.

ANALYSIS AND CALCULATION ON FRICTION AND WEAR RELIABILITY OF SOME PLANE′S FLAP MECHANISM

The mathematical model of the motion of some plane′s flap mechanism is set up by the method of establishing mathematical model of space mechanism. When the input parameter is given, the theoretical output parameter of the flap mechanism is achieved by the model. The wear and tear volume is introduced into the mathematical model, and if the input parameter is the same, the real output parameter of the flap mechanism worn can be obtained. On the basis of this, it is able to achieve the friction and the wear reliability of the flap mechanism.

The Reliability Design of a Kind of Multioption Fuze

On the basis of analysing the reliability problems existing in the general design of a kind of multioption fuze. some problems such as the reliability model. the reliability distribution of the electronic part of the fuze are discussed. For a particular multioption fuze, then.according to three different setting ways. the calculating methods of its operating reliability in six different operating states are given.

Reliability Analysis of a Mixed Redundant Model in C 3I System

Aim To define a mixed redundant model(MRM), improving the reliability of C 3I system. Methods The model combined the technology characters of two? unit system with one warm stand by unit and function substitute system. The reliability and availability equations of MRM were deduced. Results and Conclusion Compared with several other reliability models, it has obvious effect upon improving the system reliability. The effect? cost rate is very high among these models. The model can be used in reliability design, evaluation and check of C 3I system. Only a little attached cost is needed to improve C 3I system reliability effectively.

Multiple attribute decision making method based on trapezoid fuzzy linguistic variables

The problem of multiple attribute decision making under fuzzy linguistic environments, in which decision makers can only provide their preferences （attribute values）in the form of trapezoid fuzzy linguistic variables（TFLV）, is studied. The formula of the degree of possibility between two TFLVs is defined, and some of its characteristics are studied. Based on the degree of possibility of fuzzy linguistic variables, an approach to ranking the decision alternatives in multiple attribute decision making with TFLV is developed. The trapezoid fuzzy linguistic weighted averaging （TFLWA） operator method is utilized to aggregate the decision information, and then all the alternatives are ranked by comparing the degree of possibility of TFLV. The method can carry out linguistic computation processes easily without loss of linguistic information, and thus makes the decision results reasonable and effective. Finally, the implementation process of the proposed method is illustrated and analyzed by a practical example.

Transient Characteristics of a Nonlinear GaAs Photoconductive Semiconductor Switch

The transient resistance,voltage,and power of a nonlinear GaAs photoconductive semiconductor switch （PCSS） are presented by the finite difference formula to deal with the experiment data, based on the conversation of energy in the switch circuit. This method resolves the problem of directly measuring the transient characteristics of PCSS in nonlinear mode. The curve of transient voltage shows that the average electric field of PCSS in the lock-on period is always higher than the Gunn threshold,and increases monotonically. By comparing the transient power curves of the PCSS and the electrical source,it is demonstrated directly that the power shortage leads to the PCSS from the lock-on state into the selfturnoff state,so a controllable turnoff of the PCSS in lock-on by changing the distribution of the circuit power is predicted.

Precise Calculation System of Total Mix Ration for Lactating Cow

[Objective] The paper was to precisely predict nutrient requirements and optimize ration formula, and explore the inherent feature of ration optimization of dairy cow. [Method] Based on cornell net carbohydrate and protein system （CNCPS） with integrating dynamic prediction models on main nutrient requirements of dairy cattle recommended by NRC （2001） and the CNCPS parameter database accumu- lated by Chinese feed database, the ration nutrient requirement dynamic calculation and total mixed ration （TMR） formula optimizing system for Holstein dairy cow was developed using FOXPRO database system and parametric linear programming algo- rithm. [Result] By optimizing a specific cow ration and analyzing its completed nutri- ents, the results showed that this system could entirely consider a lots of nutrient balances, such as concentrate fraction and forage fraction balance, rumen degrad- able protein and rumen undergradable protein balance, crude protein and lactation net energy balance, fibrous substances （ADF, NDF） and non-fiber carbohydrates （NFC） balance, calcium and phosphate balance, electrolytes balance and trace ele- ment balance etc., and could also calculate intestinal amino acid flow in terms of different models. [Conclusion] By using dynamic mathematical equations and comput- erized program, it can be realized for the ration formula design of lactating cow with all-round interoperable but mutual-constraining each other among ration nutrients.

Integrated power electronics module based on chip scale packaged power devices

High performance can be obtained for the integrated power electronics module（IPEM） by using a three-dimensional packaging structure instead of a planar structure. A three- dimensional packaged half bridge-IPEM （HB-IPEM）, consisting of two chip scale packaged MOSFETs and the corresponding gate driver and protection circuits, is fabricated at the laboratory. The reliability of the IPEM is controlled from the shape design of solder joints and the control of assembly process parameters. The parasitic parameters are extracted using Agilent 4395A impedance analyzer for building the parasitic parameter model of the HB- IPEM. A 12 V/3 A output synchronous rectifier Buck converter using the HB-IPEM is built to test the electrical performance of the HB-IPEM. Low voltage spikes on two MOSFETs illustrate that the three-dimensional package of the HB-IPEM can decrease parasitic inductance. Temperature distribution simulation results of the HB-IPEM using FLOTHERM are given. Heat dissipation of the solder joints makes the peak junction temperature of the chip drop obviously. The package realizes three-dimensional heat dissipation and has better thermal management.

Realization of Fully Differential Fourth-Order Bessel Filter with Accurate Group Delay

A fully differential R-MOSFET-C fourth-order Bessel active lowpass filter employing fully differential operational amplifier,passive resistors,and current-steering MOS transistors as a variable resistor is proposed.This proposed implementation relies on the tunability of current-steering MOS transistors operating in the triode region counteracting the concert deviation of resistor in the integrated circuit manufacturing technology in orde r that the group delay of Bessel active filter could be designed accurately.The amplifier is not only with voltage common-mode negative feedback,but also with current common-mode negative feedback,which will benefit for the stability of its D C operating point.0.75μs group delay fourth-order Bessel lowpass filter,whic h is synthesized according to passive doubly terminated RLC prototype lowpass filter,demonstrates better than -65dB THD using 100kHz,2.5V pp signal in Taiwan UMC 2P2M(2-poly,2-metal)5.0V,0.5μm CMOS technology.

Adaptive Layout Partitioning for Dark Field Alternating Phase-Shift Mask Design

A new partitioning methodology is presented to accelerate 130nm and beyond large scale alternating phase shift mask(Alt PSM) design flow.This method deals with granularity self adaptively.Phase conflicts resolution approaches are described and strategies guaranteeing phase compatible during layout compaction are also discussed.An efficient CAD prototype for dark field Alt PSM based on these algorithms is implemented.The experimental results on several industry layouts show that the tool can successfully cope with the rapid growth of phase conflicts with good quality and satisfy lower resource consumption with different requirements of precision and speedup.

APPLICATION OF HUMAN COGNITIVE MODEL FOR TIME DEPENDENT OPERATOR BEHAVIOR IN CHINESE NPP

This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of calculation for human error probability during anticipated transient without scram (ATWS) based on the data drew from the recent experiment is offered.

EFFICIENT METHOD FOR MULTIDISCIPLINARY DESIGN OPTIMIZATION BY CONSIDERING UNCERTAINTY

A new reliability-based multidisciplinary design optimization （RBMDO） framework is proposed by combining the single-loop-based reliability analysis （SLBRA） method with multidisciplinary feasible （MDF） method. The Kriging approximate model with updating is introduced to reduce the computational cost of MDF caused by the complex structure. The computational efficiency is remarkably improved as the lack of iterative process during reliability analysis. Special attention is paid to a turbine blade design optimization by adopting the proposed method. Results show that the method is much more efficient than the commonly used double-loop based RBMDO method. It is feasible and efficient to apply the method to the engineering design.

Transformer real-time reliability model based on operating conditions

Operational reliability evaluation theory reflects real-time reliability level of power system. The component failure rate varies with operating conditions. The impact of real-time operating conditions such as ambient temperature and transformer MVA (megavolt-ampere) loading on transformer insulation life is studied in this paper. The formula of transformer failure rate based on the winding hottest-spot temperature (HST) is given. Thus the real-time reliability model of transformer based on oper- ating conditions is presented. The work is illustrated using the 1979 IEEE Reliability Test System. The changes of operating conditions are simulated by using hourly load curve and temperature curve, so the curves of real-time reliability indices are ob- tained by using operational reliability evaluation.

Fuzzy Random Reliability Analysis of Blocky Rock-Mass in Slopes

Slope stability assessment is a geotechnical problem characterized by many sources of uncertainty. In clas- sical reliability analysis, only the randomness of uncertainties is taken into account but the fuzziness of them is ignored. In this paper, a fuzzy probability approach and a fuzzy JC method are presented for the reliability analysis. The two methods have been applied to stability analysis of a certain slope of permanent ship lock in the Three-Gorges Project. The results obtained from these two methods are basically the same. However, compared with the fuzzy probability means, the fuzzy JC method can reflect the real situation better because it uses a fuzzy-based analysis applied to not only limit state equation but also mechanical parameters.

Investigating a potential reservoir landslide and suggesting its treatment using limit-equilibrium and numerical methods

A reservoir landslide not only reduces the water storage capacity, but also causes extensive damages to the dam body, power/water transmission lines, roads, and other infrastructures. The Latian Dam, located 35 km north east of Tehran （Iran）, is one of the cases which has encountered serious problems with instability of its rock abutments. This paper addresses the stability analysis of the right abutment of the Latian Dam using limit equilibrium and numerical methods. Geomechanical characteristics of the rock abutment were first estimated based on engineering classification of the rock mass. Different search methods were examined for locating the critical circular/non-circular slip surface in conjunction with the general limit equilibrium method. The effect of variabi]ity of rock mass properties, water table, and earthquake load on the factor of safety （FS） and probability of failure （PF） was studied. In the event of rapid drawdown in the reservoir, the limit equilibrium analysis calculated FS=1.067 and PF=21.1%, and the numerical analysis returned FS=1.01. The results of the analyses suggest that the right abutment of the Latian Dam is prone to slide and needs treatment. Investigations demonstrated that a slope reduction by 15° at the upper part of the abutment would meet stability conditions even in the worst-case scenario （FS=1.297 and PF=2.07%）.