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1.
本文引进矩阵的正交不变范数,定义出矩阵估计量的优良性准则,在通常的容许性意义下,得到了带有线性约束的共同均值矩阵的线性估计是泛可容许的充要条件,进而得到了在不同的线性约束条件下,的泛可容许估计类之间的一种刻划。 相似文献
2.
以多刚体动力学理论为基础,推导了自由漂浮状态双臂空间机器人系统的动量矩守恒关系,转化为系统状态方程;结合基于实数编码的遗传算法实现了双臂空间机器人姿态、关节协调运动的近似最优控制算法.通过控制双臂空间机器人的关节运动,可以同时获得载体姿态及机械臂关节期望的终了位置.仿真算例验证了算法的有效性. 相似文献
3.
CHEN QINGPING 《郧阳师范高等专科学校学报》1996,(3)
In this paper, we give a class of fuation and use to dicuss general admissibility according to general optimality ceriteria defined uader restricted growth curve model. General admissible characterization are obtained. Moreover, these conditions are then utilize to characterize infulueace that restrictions involved in growth curve model have on the class of admissible linear estimators 相似文献
4.
Willy Lens Marlies Lacante Maarten Vansteenkiste Dora Herrera 《European Journal of Psychology of Education - EJPE》2005,20(3):275-287
In order to understand and predict students’ achievement and persistence at learning activities, many contemporary motivational
models consider how much students are motivated for their school work. However, students’ achievement and persistence might
not only be affected by their amount of study motivation, but also by the motivation to engage in competing alternative activities,
as suggested three decades ago by Atkinson and Birch in their “Dynamics of Action” (1970). Building on this line of theorizing,
the present contribution indicates that it is not only instructive to consider the level of students’ motivation for these
competing activities, but also the type of activities they engage in, that is leisure vs. working activities. Two studies
demonstrated that whereas time spent on working activities is inversely related to study motivation, attitude, persistence
and academic achievement, such relationships were not found for leisure time engagement. Spending some time on leisure time
activities does not interfere with optimal learning. 相似文献
5.
We present a new algorithm for nesting problems. Many equally spaced points are set on a sheet, and a piece is moved to one
of the points and rotated by an angle. Both the point and the rotation angle constitute the packing attitude of the piece.
We propose a new algorithm named HAPE (Heuristic Algorithm based on the principle of minimum total Potential Energy) to find
the optimal packing attitude at which the piece has the lowest center of gravity. In addition, a new technique for polygon
overlap testing is proposed which avoids the time-consuming calculation of no-fit-polygon (NFP). The detailed implementation
of HAPE is presented and two computational experiments are described. The first experiment is based on a real industrial problem
and the second on 11 published benchmark problems. Using a hill-climbing (HC) search method, the proposed algorithm performs
well in comparison with other published solutions. 相似文献
6.
考虑纵向数据半参数回归模型:Y=Xβ+g(T)+ε,基于最小二乘法和局部线性拟合的方法建立了模型中参数分量β,回归函数g(·)和误差方差σ2的估计量,并在适当条件下得到了它们的渐近正态性和最优收敛速度. 相似文献
7.
A new optimization algorithm based on chaos 总被引：8，自引：0，他引：8
LU Hui-juan ZHANG Huo-ming MA Long-hua 《浙江大学学报(A卷英文版)》2006,7(4):539-542
INTRODUCTION Chaos (Wang et al., 2002) is a common nonlin- ear phenomenon, whose action is complex and similar to that of randomness. The characteristics of chaos being highly sensitive to the initial value of chaos make a world of differences due to the ergodic prop- erty of the phase space—chaos can go through all states in certain ranges without repetition; the inher- ent randomness of the system—means that chaos behavior is similar to randomness which is disorderly; but at the same t… 相似文献
8.
Jun-hai SHI Zhi-dan ZHONG Xin-jian ZHU Guang-yi CAO 《浙江大学学报(A卷英文版)》2008,9(3):401-409
This study presents a robust design method for autonomous photovoltaic （PV）-wind hybrid power systems to obtain an optimum system configuration insensitive to design variable variations. This issue has been formulated as a constraint multi-objective optimization problem, which is solved by a multi-objective genetic algorithm, NSGA-II. Monte Carlo Simulation （MCS） method, combined with Latin Hypercube Sampling （LHS）, is applied to evaluate the stochastic system performance. The potential of the proposed method has been demonstrated by a conceptual system design. A comparative study between the proposed robust method and the deterministic method presented in literature has been conducted, The results indicate that the proposed method can find a large mount of Pareto optimal system configurations with better compromising performance than the deterministic method. The trade-off information may be derived by a systematical comparison of these configurations, The proposed robust design method should be useful for hybrid power systems that require both optimality and robustness. 相似文献
9.
Quadratic 0-1 problems with linear inequality constraints are briefly considered in this paper.Global optimality conditions for these problems,including a necessary condition and some sufficient conditions,are presented.The necessary condition is expressed without dual variables.The relations between the global optimal solutions of nonconvex quadratic 0-1 problems and the associated relaxed convex problems are also studied. 相似文献
10.
Quadratic 0-1 problems with linear inequality constraints are briefly considered in this paper.Global optimality conditions for these problems,including a necessary condition and some sufficient conditions,are presented.The necessary condition is expressed without dual variables.The relations between the global optimal solutions of nonconvex quadratic 0-1 problems and the associated relaxed convex problems are also studied. 相似文献
11.
针对多元正态线性模型,根据Zellner提出的平衡损失函数,对其进行变形,定义了更一般的平衡损失函数。研究了在该损失下,多元正态线性模型回归系数矩阵的线性估计在一切估计类中的可容许性,并给出了充要条件。该方法同样适用于线性估计类中的可容许性以及其他的可容许性的研究。 相似文献
12.
王新华 《深圳信息职业技术学院学报》2007,5(1):35-38
建立了易拉罐尺寸设计的优化模型,得到了正圆柱形罐尺寸设计的最优解和上部为正圆台下部为正圆柱形罐以及CCB-1A型罐尺寸设计的次优解。作为例证,检验了椰树牌椰奶245ml罐尺寸设计的最优性和王老吉凉茶310ml罐及可口可乐汽水355ml罐尺寸设计的次优性,从而回答了2006年全国大学生数学建模竞赛C题所提出的问题。 相似文献
13.
One approach to measuring unsigned differential test functioning is to estimate the variance of the differential item functioning (DIF) effect across the items of the test. This article proposes two estimators of the DIF effect variance for tests containing dichotomous and polytomous items. The proposed estimators are direct extensions of the noniterative estimators developed by Camilli and Penfield (1997) for tests composed of dichotomous items. A small simulation study is reported in which the statistical properties of the generalized variance estimators are assessed, and guidelines are proposed for interpreting values of DIF effect variance estimators. 相似文献
14.
Daniel F. McCaffrey Katherine E. Castellano J. R. Lockwood 《Educational Measurement》2015,34(1):15-21
Student growth percentiles (SGPs) express students' current observed scores as percentile ranks in the distribution of scores among students with the same prior‐year scores. A common concern about SGPs at the student level, and mean or median SGPs (MGPs) at the aggregate level, is potential bias due to test measurement error (ME). Shang, vanIwaarden, and Betebenner (SVB; this issue) develop a simulation‐extrapolation (SIMEX) approach to adjust SGPs for test ME. In this paper, we use a tractable example in which different SGP estimators, including SVB's SIMEX estimator, can be computed analytically to explain why ME is detrimental to both student‐level and aggregate‐level SGP estimation. A comparison of the alternative SGP estimators to the standard approach demonstrates the common bias‐variance tradeoff problem: estimators that decrease the bias relative to the standard SGP estimator increase variance, and vice versa. Even the most accurate estimator for individual student SGP has large errors of roughly 19 percentile points on average for realistic settings. Those estimators that reduce bias may suffice at the aggregate level but no single estimator is optimal for meeting the dual goals of student‐ and aggregate level inferences. 相似文献
15.
16.
对于求解线性规划问题提出了一个基于尺度中心路径的预估-矫正光滑化方法.在适当的假设条件下,证明了方法的全局和局部二次收敛性.特别,在方法的局部二次收敛性分析中,不需要假定线性规划的解是唯一的.文中的方法可以推广到P0-线性互补问题和单调线性互补问题. 相似文献
17.
BAI Lei-shi HE Li-ming TIAN Zuo-hua SHI Song-jiao 《浙江大学学报(A卷英文版)》2006,7(10):1733-1741
INTRODUCTION Due to increasing demand for higher perform- ance, as well as for higher safety and reliability standards, the model-based approaches to fault de- tection and isolation (FDI) for dynamic systems have received more and more attention during the last two decades (Chen and Patton, 1999; Chen and Saif, 2006 Frank and Ding, 1997; Gao and Wang, 2006; Jiang and Zhou, 2005; Zhou et al., 1998). Among these model-based approaches, the most common way is the observer-based approach… 相似文献
18.
徐瑞 《Frontiers of Education in China》2009,4(1):94-110
Using the method of purpositive sampling, this research makes an empirical study on the relationship between the schooling
for education and democratic qualities of public high school students in Beijing. The results show that the democratic qualities
of the students in public high school of Beijing are better as a whole, but they are still lack of democratic knowledge and
abilities, etc. The results of correlation analysis, multiple regression analysis and independent-samples T test show that there are four different kinds of relationships between the schooling for education and democratic qualities
of students. Firstly, there is little distinct correlation between school reputation and democratic knowledge, attitude and
abilities of students. Secondly, there is little distinct correlation between prospective achievement and democratic knowledge
and attitude of students, but have a large correlation with the democratic abilities of students (P<.001). Thirdly, there is a large correlation between teaching and democratic knowledge, attitude and abilities of students
(P<.001). Lastly, there is a large correlation between activities participation and democratic knowledge, attitude and abilities
of students (P<.001)
__________
Translated from Jiaoyu Xuebao 教育学报 (Journal of Educational Studies), 2008, 4(1): 14–18, with updated and additional content 相似文献
19.
This paper proposes a design optimization method for the multi-objective orbit design of earth observation satellites, for which the optimality of orbit performance indices with different units, such as: total coverage time, the frequency of coverage, average time per coverage and maximum coverage gap, etc. is required simultaneously. By introducing index normalization method to convert performance indices into dimensionless variables within the range of [0, 1], a design optimization method based on the principal component analysis and cluster analysis is proposed, which consists of index normalization method, principal component analysis, multiple-level cluster analysis and weighted evaluation method. The results of orbit optimization for earth observation satellites show that the optimal orbit can be obtained by using the proposed method. The principal component analysis can reduce the total number of indices with a non-independent relationship to save computing time. Similarly, the multiple-level cluster analysis with parallel computing could save computing time. 相似文献
20.
The attitude construct is widely used by teachers and researchers in mathematics education. Often, however, teachers’ diagnosis
of ‘negative attitude’ is a causal attribution of students’ failure, perceived as global and uncontrollable, rather than an
accurate interpretation of students’ behaviour, capable of steering future action. In order to make this diagnosis useful
for dealing with students’ difficulties in mathematics, it is necessary to clarify the construct attitude from a theoretical viewpoint, while keeping in touch with the practice that motivates its use. With this aim, we investigated
how students tell their own relationship with mathematics, proposing the essay “Me and maths” to more than 1,600 students
(1st to 13th grade). A multidimensional characterisation of a student’s attitude towards mathematics emerges from this study.
This characterisation and the study of the evolution of attitude have many important consequences for teachers’ practice and
education. For example, the study shows how the relationship with mathematics is rarely told as stable, even by older students:
this result suggests that it is never too late to change students’ attitude towards mathematics. 相似文献