基于Elman网络的过热汽温隐式广义预测控制

过热蒸汽温度具有时变、大迟延、大惯性的特点,使用传统的PID控制器很难取得满意的效果。针对这一问题,提出了基于Elman网络的过热汽温隐式广义预测控制系统。采用Elman网络作为被控对象的预测模型,在求解最优控制增量时直接辩识控制器的参数,使得对象的建模方便而且控制系统的在线计算量小。仿真结果表明,此控制系统具有优良的控制性能。     

UHF机械调谐器调谐电容片形的程序设计

采用传输线理论可以计算机械式UHF调谐器对应不同频率点的调谐电容量。在进行满足直线频率关系的调谐电容片形设计时,应当求出调谐电容量Cr与旋转角θ的显式函数关系。但对于分布参数的电路,这有一定的困难。本文采用数值计算方法完成了具有良好直线频率跟踪特性的调谐电容片形的设计,并由计算机自动绘出了片形。     

果蝇DNA和基因间序列的两个信息参数沿染色体分布

以果蝇染色体的全序列和基因间序列作为研究对象.分别用描述序列构成的两个信息参数X和F分析两类序列沿着染色体分布特征,并着重讨论染色体着丝粒及其周围区域的分布规律,用线性拟合和多项式拟合分析染色体各类序列沿染色体的统计分布特征(学生t检验),分析各个参数的平均值在染色体不同区域的分布.     

罗斯308肉鸡Gompertz生长模型的建立

为掌握罗斯308肉鸡生长发育的特点和规律,测量了0～5周龄罗斯308肉鸡的体重,计算了标准差、变异系数和均匀度等指标,建立了Gompertz生长模型,获得了生长发育参数和生长发育指标。结果表明:Gompertz生长模型能很好地模拟罗斯308肉鸡的生长过程,模型参数A、B、k分别为6 098.92、4.68、0.26,R^2为0.999 5;根据该模型计算的拐点周龄为5.94周,拐点日龄为41.55 d,拐点体重为2 243.67 g,最大周增重为583.35g,最大日增重为83.34 g;累积生长、绝对生长和相对生长都符合肉鸡生长发育的一般规律。此研究结果可以作为合理饲养和优化管理的重要参考。     

Estimating Standardized SEM Parameters Given Nonnormal Data and Incorrect Model: Methods and Comparison

When both model misspecifications and nonnormal data are present, it is unknown how trustworthy various point estimates, standard errors (SEs), and confidence intervals (CIs) are for standardized structural equation modeling parameters. We conducted simulations to evaluate maximum likelihood (ML), conventional robust SE estimator (MLM), Huber–White robust SE estimator (MLR), and the bootstrap (BS). We found (a) ML point estimates can sometimes be quite biased at finite sample sizes if misfit and nonnormality are serious; (b) ML and MLM generally give egregiously biased SEs and CIs regardless of the degree of misfit and nonnormality; (c) MLR and BS provide trustworthy SEs and CIs given medium misfit and nonnormality, but BS is better; and (d) given severe misfit and nonnormality, MLR tends to break down and BS begins to struggle.     

A genetic algorithm for dynamic parameters reverse deduction of integrated anchorage system

1 Introduction The widely used detection methods of anchorage quality in China are mainly on the local anti-pull tests. In recent twenty years, the studies for the non-destructive detection of anchor bar are well developed because of the compactness combi…     

土的结构性损伤与损伤模型问题探讨

阐述土的结构性变化与损伤的关系，指出软粘土的结构性损伤包括应力损伤和扰动损伤，并在e-log曲线上探讨峰值损伤应力的合理取值和扰动损伤的定量评价。介绍复合体损伤模型，基于软粘土结构性损伤的含义。重点引荐修正损伤变量演化函数式(5a)，并从复合体概念出发，对损伤参数的合理确定提出了探讨意见与建议。     

Between-School Variation in Students' Achievement,Motivation, Affect,and Learning Strategies: Results from 81 Countries for Planning Group-Randomized Trials in Education

To plan group-randomized trials where treatment conditions are assigned to schools, researchers need design parameters that provide information about between-school differences in outcomes as well as the amount of variance that can be explained by covariates at the student (L1) and school (L2) levels. Most previous research has offered these parameters for U.S. samples and for achievement as the outcome. This paper and the online supplementary materials provide design parameters for 81 countries in three broad outcome categories (achievement, affect and motivation, and learning strategies) for domain-general and domain-specific (mathematics, reading, and science) measures. Sociodemographic characteristics were used as covariates. Data from representative samples of 15-year-old students stemmed from five cycles of the Programme for International Student Assessment (PISA; total number of students/schools: 1,905,147/70,098). Between-school differences as well as the amount of variance explained at L1 and L2 varied widely across countries and educational outcomes, demonstrating the limited generalizability of design parameters across these dimensions. The use of the design parameters to plan group-randomized trials is illustrated.     

群力水库帷幕灌浆试验及效果分析

帷幕灌浆是进行水库防渗处理的常用方法．但工程大都按规范和经验进行设计和施工，笔者结合凤翔群力水库帷幕灌浆进行了灌浆试验．研究了灌浆工艺和灌浆过程中几种技术参数的影响因素及对工程效果的影响，取得了一些有用的技术参数和质量控制指标．对类似工程的施工设计和施工技术及灌浆效果分析具有一定参考价值和工程意义。     

Fuzzy prediction and experimental verification of road surface cleaning rate by pure waterjets

INTRODUCTION Waterjet cleaning technology is mainly achieved by an erosion process of high pressure water to re-move coating materials.Louis and Schikorr(1982)identified deposits removed by high-speed waterjet cleaning as rust,oil,rubber,organics,etc.,and inves-tigated the relationship between the properties of the deposits and substrata.Summers(1982)investigated the correlation between the standoff distance,pres-sure and cleaning effectiveness.Saunders and Barton(1986)investigated the r…