基于分层贝叶斯模型的齿轮弯曲疲劳试验分析

常规齿轮弯曲疲劳试验数据处理方法是基于最小二乘法（LSE）等传统频率理论的,在小样本条件下可靠度应力寿命（P-S-N）曲线易发生拟合失真。基于成组法开展了8620H钢表面渗碳齿轮的弯曲疲劳试验,将贝叶斯理论应用于小样本条件下弯曲疲劳试验数据分析,建立了齿轮弯曲疲劳试验数据的分层贝叶斯（HBM）模型,并通过Gibbs采样获得了参数的后验分布,得到齿轮弯曲疲劳P-S-N曲线。同时以50%和99%可靠度下S-N曲线相对斜率比为评价指标,对比了LSE模型与HBM模型拟合效果,结果表明：随着试验样本数据量的变化,HBM模型的相对斜率比α波动变化率为传统LSE模型的1/40,小样本条件下HBM模型结果优于传统的LSE模型结果。HBM模型可推广应用至齿轮接触疲劳试验等数据分析中。     

Effect of interfacial imperfection on bending behavior of composites and sandwich laminates by an efficient C0 FE model

The bending behavior of composites and sandwich plates having imperfections at the layer interfaces is investigated by a refined higher order shear deformation plate theory (RHSDT) and a Least Square Error (LSE) method. In this theory, the in-plane displacement field is obtained by superposing a globally varying cubic displacement field on a zig-zag linearly varying displacement field. This plate theory represents parabolic through thickness variation of transverse shear stresses which satisfy the inter-laminar continuity condition at the layer interfaces and zero transverse shear stress condition at the top and bottom of the plate. In this plate model, the interfacial imperfection is represented by a liner spring-layer model. Finite element method is adopted and an efficient C⁰ continuous 2D finite element (FE) model is developed based on the above mentioned plate theory for the static analysis of composites and sandwich laminates having imperfections at the layer interfaces. In this model, the first derivatives of transverse displacement have been treated as independent variables to circumvent the problem of C¹ continuity associated with the above plate theory (RHSDT). The LSE method is applied to the 3D equilibrium equations of the plate problem at the post-processing stage, after in-plane stresses are calculated by using the above FE model based on RHSDT. The proposed model is implemented to analyze the laminated composites and sandwich plates having interfacial imperfection. Many new results are also presented which should be useful for the future research.     

Stochastic Regression Model with Dependent Disturbances

In this paper, we consider the estimation of the coefficient of a stochastic regression model whose explanatory variables and disturbances are permitted to exhibit short-memory or long-memory dependence. Three estimators of the coefficient are proposed. A variety of their asymptotics are illuminated under various assumptions on the explanatory variables and the disturbances. Numerical studies of the theoretical results are given. They show some unexpected aspects of the asymptotics of the three estimators.     

加速可靠性增长模型研究

建立产品可靠性在环境应力水平和增长时间段上二维变化的加速可靠性增长模型,给出了模型参数的最小二乘估计(LSE)和模型的拟合优度检验方法,有效地解决不同应力水平产品平均故障间隔时间(MTBF)的转换难题,为加速可靠增长问题的解决提供了新的思路。最后用具体的算例,验证了模型的正确性。     

Efficient 2D thermo-mechanical analysis of composites and sandwich laminates

The static behavior of composites and sandwich plates in thermo-mechanical environment is investigated by a two dimensional (2D) FE model. An efficient higher-order zig-zag theory (HOZT) considering actual through-thickness temperature profile and a least square error (LSE) method to accurately predict the inter-laminar stresses is implemented in this model. The in-plane displacement field is obtained by superposing a cubically varying global displacement field on a zig-zag displacement field having different slopes at each layer. This plate theory represents parabolic through thickness variation of transverse shear stresses, which satisfy the inter-laminar continuity at the layer interfaces and zero transverse shear stress conditions at the top and bottom of the plate. In the present 2D finite element (FE) model, the first derivatives of transverse displacement have been treated as independent variables to circumvent the problem of C¹ continuity associated with the above plate theory (HOZT). The accurate through-thickness distribution of temperature is obtained by using a linear zig-zag thermal lamination theory proposed by the authors by using the thermal conduction properties of different constituent layers in the thickness direction. The LSE method is applied at the postprocessing stage to accurately calculate the inter-laminar stresses by the 3D equilibrium equations of the plate problem, after in-plane stresses are calculated. The proposed combined FE model (HOZT+LSE) is implemented to analyze the static behavior of laminated composites and sandwich plates subjected to thermo-mechanical loadings. Many new results are also presented that should be useful for the future reference.     

LSE：一种处理器体系结构软件仿真器开发工具

在现代处理器体系结构设计中,利用软件仿真技术对设计结果进行验证是最重要的方面之一.然而,处理器体系结构仿真器的开发是一个非常困难的过程.主要的困难表现在三个方面:第一,目前用于处理器体系结构仿真器开发的编程语言如C或C 语言都是串行执行的语言,而处理器的各部件是可以并行运行的,使用串行编程语言编程来模拟并行执行的部件需要长时间的、仔细的程序功能与部件功能的匹配工作,并且容易出错;第二,使用串行程序来模拟并行部件的运行,模拟速度很低,并且仿真速度低是处理器体系结构软件仿真器开发领域的瓶颈问题;最后,仿真器仿真结果的可信度低也是一个关键问题.本文首先介绍了一种新的处理器体系结构软件仿真器开发工具,然后深入分析了该开发工具的优点和缺点,最后对该仿真器开发环境提出了改进方案.     

数字图像恢复的迭代投影正则化方法研究

图像恢复的目的是对模糊的图像进行处理,使它趋向于复原的或没有噪声影响的理想图像。研究图像恢复的迭代正则化方法,主要研究梯度法,特别是提出了求图像恢复的投影共轭梯度法。针对受大气扰动影响的遥感图像,根据梯度法使用MATLAB进行编程,对模糊且带噪音的图像进行恢复,并与经典的最小二乘法进行比较。     

INFERENCE FOR A SPECIAL BILINEAR TIME‐SERIES MODEL

It is well known that estimating bilinear models is quite challenging. Many different ideas have been proposed to solve this problem. However, there is not a simple way to do inference even for its simple cases. This article proposes a generalized autoregressive conditional heteroskedasticity‐type maximum likelihood estimator for estimating the unknown parameters for a special bilinear model. It is shown that the proposed estimator is consistent and asymptotically normal under only finite fourth moment of errors.     

基于智能电能表的居民需求响应协同策略

随着新能源大量接入,传统由发电跟踪负荷变化的运行模式面临挑战。需求响应是重要的调度资源,信息技术的发展提高了居民负荷的响应能力。在此背景下,负荷服务实体（LSE）通过电价机制协调用户的响应实现供需互动。首先,对家用电器设备的分类和建模得到响应电价的优化模型,建立了基于智能电表的家庭能源管理系统（HEMS）。其次,根据负荷服务实体的供电成本函数得到电价制定模型。以电价和响应功率作为互动信息协调不同用户的响应,进行迭代计算直到收敛,实现整体优化。考虑到用户优化会导致总成本振荡无法收敛,在优化目标函数中添加连续两次迭代间负荷变化的惩罚项。最后,通过算例仿真,分析了上述协同优化策略对LSE和用户的影响,验证了所提策略在平滑功率曲线和降低用户成本的效果。     

发电机组励磁系统参数辨识原理及方法

论述了发电机组励磁系统参数辨识的原理,介绍了时域PLPF和频域FFT／LSE的参数辨识方法,对江苏电网的典型发电机励磁系统进行了参数辨识,并验证了辨识结果的正确性。在此基础上分析了各辨识方法的优缺点。