The First-Order Comprehensive Sensitivity Analysis Methodology (1^st-CASAM) for Scalar-Valued Responses: II. Illustrative Application to a Heat Transport Benchmark Model

This work illustrates the application of the 1st-CASAM to a paradigm heat transport model which admits exact closed-form solutions. The closed-form expressions obtained in this work for the sensitivities of the temperature distributions within the model to the model’s parameters, internal interfaces and external boundaries can be used to benchmark commercial and production software packages for simulating heat transport. The 1st-CASAM highlights the novel finding that response sensitivities to the imprecisely known domain boundaries and interfaces can arise both from the definition of the system’s response as well as from the equations, interfaces and boundary conditions that characterize the model and its imprecisely known domain. By enabling, in premiere, the exact computations of sensitivities to interface and boundary parameters and conditions, the 1st-CASAM enables the quantification of the effects of manufacturing tolerances on the responses of physical and engineering systems.

Third Order Adjoint Sensitivity and Uncertainty Analysis of an OECD/NEA Reactor Physics Benchmark: II. Computed Sensitivities

This work presents the results of the exact computation of (180)3 = 5,832,000 third-order mixed sensitivities of the leakage response of a polyethylene-reflected plutonium (PERP) experimental benchmark with respect to the benchmark’s 180 microscopic total cross sections. This computation was made possible by applying the Third-Order Adjoint Sensitivity Analysis Methodology developed by Cacuci. The numerical results obtained in this work revealed that many of the 3rd-order sensitivities are significantly larger than their corresponding 1st- and 2nd-order ones, which is contrary to the widely held belief that higher-order sensitivities are all much smaller and hence less important than the first-order ones, for reactor physics systems. In particular, the largest 3rd-order relative sensitivity is the mixed sensitivity of the PERP leakage response with respect to the lowest energy-group (30) total cross sections of 1H (“isotope 6”) and 239Pu (“isotope 1”). These two isotopes are shown in this work to be the two most important parameters affecting the PERP benchmark’s leakage response. By comparison, the largest 1st-order sensitivity is that of the PERP leakage response with respect to the lowest energy-group total cross section of isotope 1H, having the value , while the largest 2nd-order sensitivity is . The 3rd-order sensitivity analysis presented in this work is the first ever such analysis in the field of reactor physics. The consequences of the results presented in this work on the uncertainty analysis of the PERP benchmark’s leakage response will be presented in a subsequent work.

Third-Order Adjoint Sensitivity Analysis of an OECD/NEA Reactor Physics Benchmark: I. Mathematical Framework

This work extends to third-order previously published work on developing the adjoint sensitivity and uncertainty analysis of the numerical model of a polyethylene-reflected plutonium (acronym: PERP) OECD/NEA reactor physics benchmark. The PERP benchmark comprises 21,976 imprecisely known (uncertain) model parameters. Previous works have used the adjoint sensitivity analysis methodology to compute exactly and efficiently all of the 21,976 first-order and (21,976)2 second-order sensitivities of the PERP benchmark’s leakage response to all of the benchmark’s uncertain parameters, showing that the largest and most consequential 1st- and 2nd-order response sensitivities are with respect to the total microscopic cross sections. These results have motivated extending the previous adjoint-based derivations to third-order, leading to the derivation, in this work, of the exact mathematical expressions of the (180)3 third-order sensitivities of the PERP leakage response with respect to these total microscopic cross sections. The formulas derived in this work are valid not only for the PERP benchmark but can also be used for computing the 3rd-order sensitivities of the leakage response of any nuclear system involving fissionable material and internal or external neutron sources. Subsequent works will use the adjoint-based mathematical expressions obtained in this work to compute exactly and efficiently the numerical values of these (180)3 third-order sensitivities (which turned out to be very large and consequential) and use them for a third-order uncertainty analysis of the PERP benchmark’s leakage response.

Application of sampled grating to control the lasing wavelength in complex-coupled DFB laser

This paper reports that the complex-coupled distributed feedback laser with the sampled grating has been designed and fabricated.The ＋1st order reflection of the sampled grating is utilized for laser single mode operation,which is 1.5387 μm in the experiment.The typical threshold current of the device is 30 mA,and the optical output power is about 10 mW at the injection current of 100 mA.

考虑一阶系统参与组合的复模态分解反应谱法

对地震作用下结构反应的复模态分解反应谱法进行了研究,指出在复模态分解反应谱法中,具有实特征值的模态不必组成二阶振动系统,可按一阶线性系统参与模态组合,且一阶线性系统只需要一条反应谱。给出了相应的复模态完全平方组合(CCQC)系数计算公式,该公式包括了一阶系统响应的相关函数和一阶系统响应与二阶系统响应之间的相关函数。通过算例验证了方法的可行性。

双基站GPS-RTK在一、二级控制测量中的应用

阐述了利用双基站GPS-RTK进行一、二级控制测量的方法、技术要求和注意事项,并通过实例论证了利用双基站GPS-RTK进行一、二级控制测量的可行性,最后得出利用该方法可大大提高工作效率的结论。

某EV车电动空调压缩机开启过程中噪声优化改善研究

纯电动汽车因结构与传统汽油车有差异,所以有着独特的噪声特点。针对某纯电动车在开启空调压缩机后,驾驶舱内存在较为明显的振动噪声这一问题,详细解析车辆行驶在怠速、高速、减速不同工况下,通过优化空调压缩机转速策略,降低压缩机运转功率,避开与压缩机支架模态1阶频率共振;提高压缩机转速下降速度,使压缩机振动噪声与环境噪声同比下降;消减压缩机内部动静盘运行不良摩擦,降低了压缩机作为源头的噪声大小等一系列改善措施。实车确认改善后的压缩机运转噪声得到很大的降低,从而使乘客舱内人体感受到的压缩机振动噪声都在可以接受的范围之内。

Fourth-Order Adjoint Sensitivity Analysis of an OECD/NEA Reactor Physics Benchmark: I. Mathematical Expressions and CPU-Time Comparisons for Computing 1^st-, 2^nd- and 3^rd-Order Sensitivities

This work extends to fourth-order previously published work on developing the adjoint sensitivity and uncertainty analysis of the numerical model of a polyethylene-reflected plutonium (acronym: PERP) OECD/NEA reactor physics benchmark. The PERP benchmark comprises 7477 imprecisely known (uncertain) model parameters which have nonzero values. These parameters are as follows: 180 microscopic total cross sections;7101 microscopic scattering sections;60 microscopic fission cross sections;60 parameters that characterize the average number of neutrons per fission;60 parameters that characterize the fission spectrum;10 parameters that characterize the fission source;and 6 parameters that characterize the isotope number densities. Previous works have used the adjoint sensitivity analysis methodology to compute exactly and efficiently all of the 7477 first-order and 27,956,503 second-order sensitivities of the PERP benchmark’s leakage response to all of the benchmark’s uncertain parameters. These works showed that largest response sensitivities involve the total microscopic cross sections, which motivated the recent computation of all of the (180)3 third-order sensitivities of the PERP leakage response with respect to these total microscopic cross sections. It turned out that some of these 3rd-order cross sections were far larger than the corresponding 2nd-order ones, thereby having the largest impact on the uncertainties induced in the PERP benchmark’s response. This finding has motivated the development of the original 4th-order formulas presented in this work, which are valid not only for the PERP benchmark but can also be used for computing the 4th-order sensitivities of response of any nuclear system involving fissionable material and internal or external neutron sources. Subsequent works will use the adjoint-based mathematical expressions obtained in this work to compute exactly and efficiently the numerical values of the largest fourth-order sensitivities of the PERP benchmark’s response to the total microscopic cross section and use them for a pioneering fourth-order uncertainty analysis of the PERP benchmark’s response.

表面等离子体无掩膜干涉光刻系统的数值分析(英文)

表面等离子体激元具有近场增强效应,可以代替光子作为曝光源形成纳米级特征尺寸的图像.本文数值分析了棱镜辅助表面等离子体干涉系统的参量空间,并给出了计算原理和方法.结果表明,适当地选择高折射率棱镜、低银层厚度、入射波长和光刻胶折射率,可以获得高曝光度、高对比度的干涉图像.入射波长为431nm时,选择40nm厚的银层,曝光深度可达200nm,条纹周期为110nm.数值分析结果为实验的安排提供了理论支持.

Design and performance of a complex-coupled DFB laser with sampled grating

A complex-coupled DFB laser with sampled grating has been designed and fabricated. The method uses the ＋ 1 st order reflection of the sampled grating for laser single-mode operation. The typical threshold current of the sampled grating based DFB laser is 25 mA, and the optical output is about 10 mW at the injected current of 100 mA. The lasing wavelength of the device is 1.5385 μm, which is the ＋1 st order wavelength of the sampled grating.