拟常曲率空间中的2-调和子流形为极小子流形的条件

研究了拟常曲率空间中的2-调和子流形与极小子流形.首先得到了拟常曲率空间中具有平行平均曲率的2-调和子流形为极小子流形的一个较好的充分条件,然后得到了2-调和超曲面与极小超曲面在一定条件下是等价的结论.     

将闭Riemann子流形保角变形成极小子流形

在本文中，通过外围空间的适当保角变形，我们证明了，每个Riemann子流形可以被认作一个极小子流形，我们还研究了这样得到的子流形的稳定性，定理2和3推广了Schoen和S．TYan[2]的结论．     

复射影空间CPn+p中的全实2-调和子流形

本文研究了复射影空间中的全实2 -调和子流形问题.利用活动标架法,获得了这类子流形成为极小子流形的关于第二基本形式模长的Pinching定理及一个积分不等式.此外还得到关于全实2-调和伪脐子流形的一些刚性定理,推广了CPn中全实2-调和子流形的一些相应结果.     

共形变换下极小子流形不变的条件

本文运用外微分运算的方法和在欧氏空间中将共形变换分解成若干个运动与反演变换的乘积的结果,得到在共形变换下极小子流形仍为极小子流形的条件。并且,由此得到一个推论。     

近乎Sasakian流形的CR子流形

本文定义并讨论了近乎Ｓａｓａｋｉａｎ流形的ＣＲ子流形,得到了关开这类子流形的微分几何方面的一些有意义的结果。     

复射影空间中具有平坦法丛的一般极小子流形的注记

设Mn是复射影空间CPn+p/2中具有平坦法丛的一般极小子流形.该文研究了这种子流形的曲率性质与几何性质之间的关系.运用活动标架法,得到关于Ricci曲率和第二基本形式模长的刚性定理,完善了已有文献的相关结果.此外,该文还得到具有平坦法丛的一般子流形一个重要性质.     

局部对称的黎曼流形中的极小子流形

主要研究了局部对称的黎曼流形中的定向紧致无边极小子流形的内蕴刚性问题,利用一个矩阵不等式,得到了这类子流形的一个刚性定理．所得结果部分改进了已有的一个结论．     

关于四元射影空间的一般极小子流形

本文研究四元射影空间的一般极小子流形,建立了一个积分公式,并且用此公式得到了紧致一般极小子流形的截曲率的Ｐｉｎｃｈｉｎｇ结果．     

关于局部对称空间中极小子流形的一个Ricci曲率pinching定理

研究局部对称空间中具有正Ricci曲率的完备极小子流形,得到了关于子流形Ricci曲率的一个pinching定理,把Norio Ejiri的结论从外围空间为球空间推广到局部对称空间中。     

欧氏空间中子流形的曲率与几何性质

研究了欧氏空间En p中具常数量曲率n(n-1)r的n(n>2)维完备连通子流形,得到了En p截面曲率非负且法联络平坦的完备连通子流形的一个分类定理.     

Simulation Study of an Automated Guided-vehicle System in a Yugoslav Hospital

A simulation study of an automated guided-vehicle system connected with an automated vertical transportation system in a large hospital is described. The aim of the study was to determine the allocation and size of storage space for vehicles, the minimum number of vehicles required, the accomplishment of a transportation-network timetable and the queueing situation in the system. This study is part of a simulation study of internal transportation in the new, 1100-bed University Hospital in Zagreb, Yugoslavia, which is under construction.     

New method for estimating survival curves based upon subpopulations

The overall Kaplan-Meier estimate of the survival curve underlying a study population does not individually account for the ages at which patients were first seen and thence followed up in the study. Since the number of patients in these age-specific subgroups varies quite arbitrarily for a given study, the overall Kaplan-Meier curve which assumes that all patients were seen from the beginning of the study usually either overestimates or underestimates the survival probability, depending on the varying sample sizes. In this paper, we therefore propose an estimate of the overall survival curve underlying a study population based on the individual age-specific Kaplan-Meier estimates and the probability distribution of the age at which patients were first seen in the study. In the particular case when there is no censoring, it is shown that the usual overall Kaplan-Meier survival curve which assumes that all patients irrespective of their age at entry into the study were followed from the beginning of the study is identical with the proposed estimate. This result does not seem to necessarily hold good in the presence of arbitrary censoring. Further, the estimate is unbiased and consistent, a property which the Kaplan-Meier estimate also enjoys. The efficiency of the proposed estimate relative to the Kaplan-Meier estimate is being investigated and will be reported along with results of its application in a separate communication.     

The Stokes phenomenon in the confluence of the hypergeometric equation using Riccati equation

In this paper we study the confluence of two regular singular points of the hypergeometric equation into an irregular one. We study the consequence of the divergence of solutions at the irregular singular point for the unfolded system. Our study covers a full neighborhood of the origin in the confluence parameter space. In particular, we show how the divergence of solutions at the irregular singular point explains the presence of logarithmic terms in the solutions at a regular singular point of the unfolded system. For this study, we consider values of the confluence parameter taken in two sectors covering the complex plane. In each sector, we study the monodromy of a first integral of a Riccati system related to the hypergeometric equation. Then, on each sector, we include the presence of logarithmic terms into a continuous phenomenon and view a Stokes multiplier related to a 1-summable solution as the limit of an obstruction that prevents a pair of eigenvectors of the monodromy operators, one at each singular point, to coincide.     

Convergence rates for weighted sums in noncommutative probability space

We study convergence rates for weighted sums of pairwise independent random variables in a noncommutative probability space of which the weights are in a von Neumann algebra. As applications, we first study convergence rates for weighted sums of random variables in the noncommutative Lorentz space, and second we study convergence rates for weighted sums of probability measures with respect to the free additive convolution.     

Interactive group decision-making using a fuzzy linguistic approach for evaluating the flexibility in a supply chain

With global competition rapidly intensifying and shifting to the supply chain level, the supply chain flexibility has become increasingly important. However, the literature addressing supply chain flexibility remains limited. This study thus builds a group decision-making structure model of flexibility in supply chain management development. This study presents a framework for evaluating supply chain flexibility comprising two parts, an evaluation hierarchy with flexibility dimensions and related metrics, and an evaluation scheme that uses a three-stage process to evaluate supply chain flexibility. This study then proposes an algorithm for determining the degree of supply chain flexibility using a fuzzy linguistic approach. Evaluations of the degree of supply chain flexibility can identify the need to improve supply chain flexibility, and identify specific dimensions of supply chain flexibility as the best directions for improvement. The results of this study are more objective and unbiased for two reasons. First, the results are generated by group decision-making with interactive consensus analysis. Second, the fuzzy linguistic approach used in this study has more advantage to preserve no loss of information than other methods. Additionally, this study presents an example using a case study to illustrate the availability of the proposed methods and compare it with other methods.     

Using dynamic software in mathematics: the case of reflection symmetry

This study was carried out to examine the effects of computer-assisted instruction (CAI) using dynamic software on the achievement of students in mathematics in the topic of reflection symmetry. The study also aimed to ascertain the pre-service mathematics teachers’ opinions on the use of CAI in mathematics lessons. In the study, a mixed research method was used. The study group of this research consists of 30 pre-service mathematics teachers. The data collection tools used include a reflection knowledge test, a survey and observations. Based on the analysis of the data obtained from the study, the use of CAI had a positive effect on achievement in the topic of reflection symmetry of the pre-service mathematics teachers. The pre-service mathematics teachers were found to largely consider that a mathematics education which is carried out utilizing CAI will be more beneficial in terms of ‘visualization’, ‘saving of time’ and ‘increasing interest/attention in the lesson’. In addition, it was found that the vast majority of them considered using computers in their teaching on the condition that the learning environment in which they would be operating has the appropriate technological equipment.     

On a phase-field system based on the Cattaneo law

Our aim in this paper is to study a generalization of the Caginalp phase-field system based on the Maxwell-Cattaneo law for heat conduction and endowed with Neumann boundary conditions. In particular, we obtain well-posedness results and study the dissipativity of the associated solution operators. We also prove, when the enthalpy is conserved, the existence of the global attractor. We finally study the spatial behavior of solutions in a semi-infinite cylinder, assuming that such solutions exist and have a proper (spatial) decay at infinity.     

Plane transformations in a complex setting III: similarities

This is the third part of a study of plane transformations described in a complex setting. After the study of homotheties, translations, rotations and reflections, we proceed now to the study of plane similarities, either direct or inverse. Their group theoretical properties are described, and their action on classical geometrical objects is studied.     

破坏性测量系统波动源的分析

测量系统分析是质量改进活动中的一个重要问题,评价测量系统精确度的标准方法是量具的重复性和再现性(R&R)研究,这种研究通常采用试验设计方法,而且对测量对象可以重复测量。然而在工业实践中,当遇到破坏性测量时,这种标准的R&R研究方法是无法实施的。本文给出了破坏性测量中测量系统波动源分析的一种方法,首先分析了破坏性测量中进行量具R&R研究的前提条件,进而给出了进行量具R&R研究的随机效应模型和方差分析方法;最后通过应用Minit-ab.14软件,对工业实践中的一个应用实例进行了分析。     

Existence of Global Solutions for a Class of Abstract Second-Order Nonlocal Cauchy Problem with Impulsive Conditions in Banach Spaces

In this paper, we are concerned with a class of abstract second-order nonlocal Cauchy problem with impulsive conditions in Banach spaces. First, we study the existence of mild solutions for a class of second-order nonlocal Cauchy problem with impulsive conditions in Banach spaces on an interval [0,a]. Later, we study a couple of cases where we can establish the existence of global solutions for a class of abstract second-order nonlocal Cauchy problem with impulsive conditions in Banach spaces. We apply our theory to study the existence of solutions for impulsive partial differential equations.