In uncertainty analysis and reliability-based multidisciplinary design and optimization(RBMDO)of engineering structures,the saddlepoint approximation(SA)method can be utilized to enhance the accuracy and efficiency of...In uncertainty analysis and reliability-based multidisciplinary design and optimization(RBMDO)of engineering structures,the saddlepoint approximation(SA)method can be utilized to enhance the accuracy and efficiency of reliability evaluation.However,the random variables involved in SA should be easy to handle.Additionally,the corresponding saddlepoint equation should not be complicated.Both of them limit the application of SA for engineering problems.The moment method can construct an approximate cumulative distribution function of the performance function based on the first few statistical moments.However,the traditional moment matching method is not very accurate generally.In order to take advantage of the SA method and the moment matching method to enhance the efficiency of design and optimization,a fourth-moment saddlepoint approximation(FMSA)method is introduced into RBMDO.In FMSA,the approximate cumulative generating functions are constructed based on the first four moments of the limit state function.The probability density function and cumulative distribution function are estimated based on this approximate cumulative generating function.Furthermore,the FMSA method is introduced and combined into RBMDO within the framework of sequence optimization and reliability assessment,which is based on the performance measure approach strategy.Two engineering examples are introduced to verify the effectiveness of proposed method.展开更多
In this paper,the approximate analytical oscillatory solutions to the generalized KolmogorovPetrovsky-Piskunov equation(gKPPE for short)are discussed by employing the theory of dynamical system and hypothesis undeterm...In this paper,the approximate analytical oscillatory solutions to the generalized KolmogorovPetrovsky-Piskunov equation(gKPPE for short)are discussed by employing the theory of dynamical system and hypothesis undetermined method.According to the corresponding dynamical system of the bounded traveling wave solutions to the gKPPE,the number and qualitative properties of these bounded solutions are received.Furthermore,pulses(bell-shaped)and waves fronts(kink-shaped)of the gKPPE are given.In particular,two types of approximate analytical oscillatory solutions are constructed.Besides,the error estimations between the approximate analytical oscillatory solutions and the exact solutions of the gKPPE are obtained by the homogeneity principle.Finally,the approximate analytical oscillatory solutions are compared with the numerical solutions,which shows the two types of solutions are similar.展开更多
In the recent years,error recovery circuits in optimized data path units are adopted with approximate computing methodology.In this paper the novel multipliers have effective utilization in the newly proposed two diff...In the recent years,error recovery circuits in optimized data path units are adopted with approximate computing methodology.In this paper the novel multipliers have effective utilization in the newly proposed two different 4:2 approximate compressors that generate Error free Sum(ES)and Error free Carry(EC).Proposed ES and Proposed EC in 4:2 compressors are used for performing Partial Product(PP)compression.The structural arrangement utilizes Dadda structure based PP.Due to the regularity of PP arrangement Dadda multiplier is chosen for compressor implementation that favors easy standard cell ASIC design.In this,the proposed compression idealogy are more effective in the smallest n columns,and the accurate compressor in the remaining most significant columns.This limits the error in the multiplier output to be not more than 2n for an n X n multiplication.The choice among the proposed compressors is decided based on the significance of the sum and carry signals on the multiplier result.As an enhancement to the proposed multiplier,we introduce two Area Efficient(AE)variants viz.,Proposed-AE(P-AE),and P-AE with Error Recovery(P-AEER).The proposed basic P-AE,and P-AEER designs exhibit 46.7%,52.9%,and 52.7%PDP reduction respectively when compared to an approximate multiplier of minimal error type and are designed with 90nm ASIC technology.The proposed design and their performance validation are done by using Cadence Encounter.The performance evaluations are carried out using cadence encounter with 90nm ASIC technology.The proposed-basic P-AEA and P-AEER designs demonstrate 46.7%,52.9%and 52.7%PDP reduction compared to the minimal error approximate multiplier.The proposed multiplier is implemented in digital image processing which revealed 0.9810 Structural SIMilarity Index(SSIM),to the least,and less than 3%deviation in ECG signal processing application.展开更多
为解决复杂系统多学科可靠性设计优化过程中由于存在多源不确定性和多层嵌套而导致的计算效率低的问题,将近似灵敏度技术与两级集成系统综合策略(Bi-level integrated system synthesis,BLISS)和功能测度法集成,提出一种能同时处理随机...为解决复杂系统多学科可靠性设计优化过程中由于存在多源不确定性和多层嵌套而导致的计算效率低的问题,将近似灵敏度技术与两级集成系统综合策略(Bi-level integrated system synthesis,BLISS)和功能测度法集成,提出一种能同时处理随机和区间不确定性的序列化多学科可靠性设计优化方法。基于概率论和凸模型对混合不确定性进行量化,提出一种随机和区间不确定性下的混合可靠性评价指标,并基于功能测度法建立多学科可靠性设计优化模型。采用近似灵敏度信息替代实际灵敏度值,将近似灵敏度技术同时嵌入多级多学科设计优化策略和多学科可靠性分析方法中,避免每轮循环都进行全局灵敏度信息的分析与迭代,提高了计算效率。基于序列化思想同时将四层嵌套的多学科可靠性设计优化循环和三层嵌套的多学科可靠性分析过程进行解耦,形成一个单循环顺序执行的多学科可靠性设计优化过程,避免了每轮循环对整个可靠性分析模型进行迭代分析的过程,减少灵敏度分析和多学科分析次数。以汽车侧撞工程设计为例,验证了该法具有同时处理随机和区间不确定性的能力,并且计算效率较传统方法分别提高了10.98%和23.63%,表明该法具有一定工程实用价值。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U21A20167,12072295,12192214,12192210)Applied Basic Research Project of Sichuan Province(Grant No.2021YJ0050)Fundamental Research Funds for the Central Universities(Grant No.2682021ZTPY098).
基金support from the Key R&D Program of Shandong Province(Grant No.2019JZZY010431)the National Natural Science Foundation of China(Grant No.52175130)+1 种基金the Sichuan Science and Technology Program(Grant No.2022YFQ0087)the Sichuan Science and Technology Innovation Seedling Project Funding Projeet(Grant No.2021112)are gratefully acknowledged.
文摘In uncertainty analysis and reliability-based multidisciplinary design and optimization(RBMDO)of engineering structures,the saddlepoint approximation(SA)method can be utilized to enhance the accuracy and efficiency of reliability evaluation.However,the random variables involved in SA should be easy to handle.Additionally,the corresponding saddlepoint equation should not be complicated.Both of them limit the application of SA for engineering problems.The moment method can construct an approximate cumulative distribution function of the performance function based on the first few statistical moments.However,the traditional moment matching method is not very accurate generally.In order to take advantage of the SA method and the moment matching method to enhance the efficiency of design and optimization,a fourth-moment saddlepoint approximation(FMSA)method is introduced into RBMDO.In FMSA,the approximate cumulative generating functions are constructed based on the first four moments of the limit state function.The probability density function and cumulative distribution function are estimated based on this approximate cumulative generating function.Furthermore,the FMSA method is introduced and combined into RBMDO within the framework of sequence optimization and reliability assessment,which is based on the performance measure approach strategy.Two engineering examples are introduced to verify the effectiveness of proposed method.
基金supported by the National Natural Science Foundation of China (No.11471215)。
文摘In this paper,the approximate analytical oscillatory solutions to the generalized KolmogorovPetrovsky-Piskunov equation(gKPPE for short)are discussed by employing the theory of dynamical system and hypothesis undetermined method.According to the corresponding dynamical system of the bounded traveling wave solutions to the gKPPE,the number and qualitative properties of these bounded solutions are received.Furthermore,pulses(bell-shaped)and waves fronts(kink-shaped)of the gKPPE are given.In particular,two types of approximate analytical oscillatory solutions are constructed.Besides,the error estimations between the approximate analytical oscillatory solutions and the exact solutions of the gKPPE are obtained by the homogeneity principle.Finally,the approximate analytical oscillatory solutions are compared with the numerical solutions,which shows the two types of solutions are similar.
文摘In the recent years,error recovery circuits in optimized data path units are adopted with approximate computing methodology.In this paper the novel multipliers have effective utilization in the newly proposed two different 4:2 approximate compressors that generate Error free Sum(ES)and Error free Carry(EC).Proposed ES and Proposed EC in 4:2 compressors are used for performing Partial Product(PP)compression.The structural arrangement utilizes Dadda structure based PP.Due to the regularity of PP arrangement Dadda multiplier is chosen for compressor implementation that favors easy standard cell ASIC design.In this,the proposed compression idealogy are more effective in the smallest n columns,and the accurate compressor in the remaining most significant columns.This limits the error in the multiplier output to be not more than 2n for an n X n multiplication.The choice among the proposed compressors is decided based on the significance of the sum and carry signals on the multiplier result.As an enhancement to the proposed multiplier,we introduce two Area Efficient(AE)variants viz.,Proposed-AE(P-AE),and P-AE with Error Recovery(P-AEER).The proposed basic P-AE,and P-AEER designs exhibit 46.7%,52.9%,and 52.7%PDP reduction respectively when compared to an approximate multiplier of minimal error type and are designed with 90nm ASIC technology.The proposed design and their performance validation are done by using Cadence Encounter.The performance evaluations are carried out using cadence encounter with 90nm ASIC technology.The proposed-basic P-AEA and P-AEER designs demonstrate 46.7%,52.9%and 52.7%PDP reduction compared to the minimal error approximate multiplier.The proposed multiplier is implemented in digital image processing which revealed 0.9810 Structural SIMilarity Index(SSIM),to the least,and less than 3%deviation in ECG signal processing application.
文摘为解决复杂系统多学科可靠性设计优化过程中由于存在多源不确定性和多层嵌套而导致的计算效率低的问题,将近似灵敏度技术与两级集成系统综合策略(Bi-level integrated system synthesis,BLISS)和功能测度法集成,提出一种能同时处理随机和区间不确定性的序列化多学科可靠性设计优化方法。基于概率论和凸模型对混合不确定性进行量化,提出一种随机和区间不确定性下的混合可靠性评价指标,并基于功能测度法建立多学科可靠性设计优化模型。采用近似灵敏度信息替代实际灵敏度值,将近似灵敏度技术同时嵌入多级多学科设计优化策略和多学科可靠性分析方法中,避免每轮循环都进行全局灵敏度信息的分析与迭代,提高了计算效率。基于序列化思想同时将四层嵌套的多学科可靠性设计优化循环和三层嵌套的多学科可靠性分析过程进行解耦,形成一个单循环顺序执行的多学科可靠性设计优化过程,避免了每轮循环对整个可靠性分析模型进行迭代分析的过程,减少灵敏度分析和多学科分析次数。以汽车侧撞工程设计为例,验证了该法具有同时处理随机和区间不确定性的能力,并且计算效率较传统方法分别提高了10.98%和23.63%,表明该法具有一定工程实用价值。
