Generalized likelihood ratio test for varying-coefficient models with different smoothing variables

Varying-coefficient models are popular multivariate nonparametric fitting techniques. When all coefficient functions in a varying-coefficient model share the same smoothing variable, inference tools available include the F-test, the sieve empirical likelihood ratio test and the generalized likelihood ratio (GLR) test. However, when the coefficient functions have different smoothing variables, these tools cannot be used directly to make inferences on the model because of the differences in the process of estimating the functions. In this paper, the GLR test is extended to models of the latter case by the efficient estimators of these coefficient functions. Under the null hypothesis the new proposed GLR test follows the χ²-distribution asymptotically with scale constant and degree of freedom independent of the nuisance parameters, known as Wilks phenomenon. Further, we have derived its asymptotic power which is shown to achieve the optimal rate of convergence for nonparametric hypothesis testing. A simulation study is conducted to evaluate the test procedure empirically.     

聚羟基丁酸酯球晶的微观结构及其对力学性能的影响

本文采用基于数字图像相关计算技术的显微数字分析系统,结合原子力显微镜等,实验研究了晶态高聚物聚羟基丁酸酯(PHB)的细观结构及对其力学性能的影响规律.结果发现:实验用的PHB球晶是台阶式生长或螺旋式生长,其生长台阶高度差在200nm～500nm之间;PHB球晶同心圆环随着结晶温度的提高,同心圆环的环间距增大.球晶结晶度、球晶尺寸对冲击强度、拉伸强度以及断裂伸长率的影响呈线性关系.     

Words, music, and other measures: Predicting the repertoire popularity of 597 Schubert lieder.

To address the venerable aesthetic question of the relative importance of music and words, musical and textual characteristics were used to predict recording counts of 597 Franz Schubert lieder. Predictors included career variables (age and concurrent productivity), "whole song" variables (e.g., performance duration, structural complexity, major vs. minor key), thematic measures of the first six notes of the vocal incipit (e.g., melodic and rhythmic originality), poet variables (Goethe, Schiller, etc.), and text variables (computer content analysis measures of primordial and conceptual thought and positive and negative emotions). Many correlations between predictors were small but reliable; career variables accounted for most strong correlations. A 45-predictor regression model was highly significant (R2 = .63), with 13 reliable (p     

力标准机独立加码与逆程交换研究

静重式力标准机在施加递增或递减负荷过程中，当砝码进行逆程交换时会出现逆负荷现象。为此，提出了力标准机独立加码的概念与方法，建立并讨论了独立加码方法的驱动方式、砝码加卸过程的运动规律、加卸过程中吊挂受力变化、加载稳定性和工作效率问题。研究了通过少量砝码的合理组合与交换，实现多力级等力值间隔加载的技术方法。当砝码进行逆程交换时，为减小以至消除逆负荷现象进行了理论分析和实验验证。结果表明，提出的方法是可行的和有效的。为力基、标准机的技术发展和提高提供了一种新的理论方法和试验依据，对力值计量检测技术的进步具有重要意义。     

梁板壳有限单元中的各种闭锁现象及解决方法

对梁元和板壳单元中存在的各种闭锁现象进行详细的分析，对现有的一些解决方法的优劣性进行比较，以使人们对闭锁现象有更深入的认识，并能有效地消除或减轻它们的不利影响.分别在二维、三维梁元与板壳单元有限元公式中引入Hellinger-Reissner混合函数或降阶积分，以减轻或消除闭锁现象对单元计算精度的不利影响.通过4个算例来阐明闭锁现象随单元受力情况、单元厚度、单元网格划分的不同而对结构非线性分析结果所带来的不同程度的影响. 结果表明，闭锁现象对结构的数值分析结果影响显著，对以受弯为主而膜应力很小甚至为零的单元，膜闭锁现象非常严重，而对薄壁单元，剪切闭锁的影响特别严重；采用单元的混合公式或在协调元中采用降阶积分，可有效地消除单元的各种闭锁现象和插值函数的误差对单元计算精度带来的不利影响，能使单元计算精度和计算效率得到显著改善.     

GSM系统中TCH自适应均衡解调算法的研究

针对移动信道多径效应造成的严重的符号间干扰（ISI）问题，研究了基于最大似然序列估计（MLSE）的GSM系统中TCH自适应均衡解调算法，并对这种自适应均衡解调算法在Jake移动信道模型环境下的性能进行了分析和计算机仿真，仿真结果表明，该自适应均衡解调算法能够很好地克服符号间干扰（ISI）问题，性能良好。     

炉内磷酸盐处理的隐患及对策

某电厂3号锅炉炉水存在磷酸盐隐藏现象。通过对3号锅炉炉水磷酸盐隐藏现象的过程进行追溯、分析,发现发生磷酸盐隐藏现象的主要原因是该锅炉不同测点的温度偏差较大,靠近水冷壁的火焰温度较高,有时甚至超过1400℃,认为3号锅炉炉水磷酸盐浓度控制在0.2～0.7 mg/L较合理。处理后,运行3年多进行割管检查,结果证明该处理方法取得了预期的效果。     

大型空间飞行器的高阶滑模姿态控制律设计

针对大型空间飞行器的大角度姿态控制问题,考虑航天器惯量矩阵中的不确定性和外部扰动力矩,应用高阶滑模控制方法设计了姿态跟踪控制律.采用的二阶滑模控制方法改善了系统针对不确定性及外部扰动的鲁棒性,并减弱了振颤现象.针对所设计的控制器进行了仿真验证,并与一阶滑模控制进行了对比,仿真结果表明了所提出方法的有效性.     

Discrete-time sliding mode control for uncertain systems with state and input delays

This article presents a discrete-time sliding mode control method for the robust stabilisation of linear uncertain multi-input discrete-time systems with state and input delays. The systems are assumed to have structured mismatched time-varying parameter uncertainties. A specified switching surface is proposed and a sliding mode controller is derived to ensure the existence of the quasi-sliding mode. Based on the improved Lyapunov function and linear matrix inequality technique, delay-independent sufficient conditions for the design of a stable switching surface are given and the stability of the overall closed-loop system is guaranteed. Neither chattering phenomenon will occur nor the knowledge of upper bound of uncertainties is required. Finally, simulation results demonstrate the efficacy of the proposed control methodology.     

Requiem for a theory: the ‘ story grammar’ story

Abstract

Story grammar was a fairly hot topic in artificial intelligence (AI) from the mid-1970s to the early 1980s. Now, however, it has virtually disappeared as a research issue in AI. The process of science is one where theories are proposed, experiments are conducted, hypotheses are tested, theories are revised and, ultimately, theories are either accepted or rejected. The story grammar story is surveyed with a view towards describing what it was, and explaining what happened to it, from the perspective of the scientific process.