决策支持系统中的建模知识表示研究

提出一种基于知识的建模支持系统 ,该系统的知识由三部分组成 :构模规则知识、变量类型知识以及数据映射知识 .构模规则知识描述了决策者的构模过程 ;变量类型知识定义了构模规则知识中所有变量的数据类型 ;数据映射知识描述求解过程所需数据的来源 .对于决策者输入的一个实际决策问题 ,系统能够根据问题描述按照构模知识自动进行求解 ,同时对经验进行学习 ,生成经验规则     

一般约束优化问题的摄动梯度投影法

利用梯度投影法与罚函数技巧，将带等式和不等式约束优化问题化成一个无约束问题，提出了求解不等式、等式约束优化问题的摄动梯度投影算法。考虑到计算的误差因素，在搜索方向上进行摄动，得到一个方向不精确的梯度投影法。参数δｋ取不同的数还可以得到一类梯度投影法。从而保证了在实际应用中更容易实现，在较弱的条件下，证明了该算法的全局收敛性。     

一类具有柔性臂的机器人的稳定性(英)

主要讨论了柔性臂振动系统，其弯曲振动与扭转振动的耦合表现在边界条件中．利用算子谱理论与算子半群理论，得出了系统相应的发展方程的主算子生成的算子半群的具体表达式．并证明了此半群是非紧非指数稳定的解析半群。     

线性互补方法分析网架结构极限承载力的理论及试验研究

本文从增量理论出发，推导了空间网架结构物理非线性问题的变分不等方程和相应的线性互补方程，编制了相应的计算机程序。通过对常用的几种型式网架结构的算例分析表明，网架结构有较好的极限承载力性能，且不同型式网架结构的极限承载力有很大不同，破坏路径也不一样。本文通过对正放四角锥网架的模型试验，验证了计算理论以及所得结论的正确性。     

以塑性应变和损伤为参变量的广义非局部损伤本构方程

将塑性应变和非局部损伤取为内变量，引入耗散势，利用连续介质损伤力学和热力学第二定律，建立了一个能全面描述材料本构行为的非局部非弹性损伤本构方程，用该模型计算了单位、单压状态下混凝土材料及20#钢的应力-应变关系曲线，取得了较好的结果．     

复系数Riccati方程的可积条件及其应用

给出了复系数Riccati方程的一些可积类型 ,以及一类可利用复系数Riccati方程求解二维复变系数线性系统的方法     

Using Prior Risk‐Related Knowledge to Support Risk Management Decisions: Lessons Learnt from a Tunneling Project

The authors of this article have developed six probabilistic causal models for critical risks in tunnel works. The details of the models' development and evaluation were reported in two earlier publications of this journal. Accordingly, as a remaining step, this article is focused on the investigation into the use of these models in a real case study project. The use of the models is challenging given the need to provide information on risks that usually are both project and context dependent. The latter is of particular concern in underground construction projects. Tunnel risks are the consequences of interactions between site‐ and project‐ specific factors. Large variations and uncertainties in ground conditions as well as project singularities give rise to particular risk factors with very specific impacts. These circumstances mean that existing risk information, gathered from previous projects, is extremely difficult to use in other projects. This article considers these issues and addresses the extent to which prior risk‐related knowledge, in the form of causal models, as the models developed for the investigation, can be used to provide useful risk information for the case study project. The identification and characterization of the causes and conditions that lead to failures and their interactions as well as their associated probabilistic information is assumed to be risk‐related knowledge in this article. It is shown that, irrespective of existing constraints on using information and knowledge from past experiences, construction risk‐related knowledge can be transferred and used from project to project in the form of comprehensive models based on probabilistic‐causal relationships. The article also shows that the developed models provide guidance as to the use of specific remedial measures by means of the identification of critical risk factors, and therefore they support risk management decisions. Similarly, a number of limitations of the models are discussed.     

一类含多滞量的非线性中立型差分方程的振动准则

研究了含有多个滞量的非线性中立型差分方程的振动性，得到了该类方程振动的一个充要条件     

Modeling Individual Cell Lag Time Distributions for Listeria monocytogenes

The food industry faces two paradoxical demands: on the one hand, foods need to be microbiologically safe for consumption and on the other hand, consumers want fresh, minimally processed foods. To meet these demands, more insight into the mechanisms of microbial growth is needed, which includes, among others, the microbial lag phase. This is the time needed by bacterial cells to adapt to a new environment (for example, after food product contamination) before starting an exponential growth regime. Since food products are often contaminated with low amounts of pathogenic microorganisms, it is important to know the distribution of these individual cell lag times to make accurate predictions concerning food safety. More precisely, cells with the shortest lag times (i.e., appearing in the left tail of the distribution) are largely decisive for the outgrowth of the population. In this study, an integrated modeling approach is proposed and applied to an existing data set of individual cell lag time measurements of Listeria monocytogenes. In a first step, a logistic modeling approach is applied to predict the fraction of zero-lag cells (which start growing immediately) as a function of temperature, pH, and water activity. For the nonzero-lag cells, the mean and variance of the lag time distribution are modeled with a hyperbolic-type model structure. This mean and variance allow identification of the parameters of a two-parameter Weibull distribution, representing the nonzero-lag cell lag time distribution. The integration of the developed models allows prediction of a global distribution of individual cell lag times for any combination of environmental conditions in the interpolation domain of the original temperature, pH, and water activity settings. The global fitting quality of the model is quantified using several measures indicating that the model gives accurate predictions, erring slightly on the fail-safe side when predicting the shortest lag times.     

Cancer Dose-Response Modeling of Epidemiological Data on Worker Exposures to Aldrin and Dieldrin

The paper applies classical statistical principles to yield new tools for risk assessment and makes new use of epidemiological data for human risk assessment. An extensive clinical and epidemiological study of workers engaged in the manufacturing and formulation of aldrin and dieldrin provides occupational hygiene and biological monitoring data on individual exposures over the years of employment and provides unusually accurate measures of individual lifetime average daily doses. In the cancer dose-response modeling, each worker is treated as a separate experimental unit with his own unique dose. Maximum likelihood estimates of added cancer risk are calculated for multistage, multistage-Weibull, and proportional hazards models. Distributional characterizations of added cancer risk are based on bootstrap and relative likelihood techniques. The cancer mortality data on these male workers suggest that low-dose exposures to aldrin and dieldrin do not significantly increase human cancer risk and may even decrease the human hazard rate for all types of cancer combined at low doses (e.g., 1 g/kg/day). The apparent hormetic effect in the best fitting dose-response models for this data set is statistically significant. The decrease in cancer risk at low doses of aldrin and dieldrin is in sharp contrast to the U.S. Environmental Protection Agency's upper bound on cancer potency based on mouse liver tumors. The EPA's upper bound implies that lifetime average daily doses of 0.0000625 and 0.00625 g/kg body weight/day would correspond to increased cancer risks of 0.000001 and 0.0001, respectively. However, the best estimate from the Pernis epidemiological data is that there is no increase in cancer risk in these workers at these doses or even at doses as large as 2 g/kg/day.