具有时滞和治疗的丙肝模型分析

为了进一步研究丙型肝炎病毒的传播机理及其治疗的有效方法,针对丙型肝炎病毒潜伏期比较长,且在整个患病期内均具有传染性的特性,在已有的模型基础上引入时滞来反映丙肝潜伏期的存在。为研究时滞和药物治疗对丙肝传染病的影响,建立了具有常数输入和时滞的丙肝传染病模型,利用常微分方程定性理论知识分析其对应平衡点的存在,构造Liapunov函数讨论无病平衡点的全局稳定性,并且分析了时滞对系统的影响。通过分析可知,当时滞大于零且基本再生数小于1时,系统在无病平衡点处是全局渐近稳定的。给出了正平衡点稳定、不稳定与系统产生Hopf分支分别对应的前提条件,通过对阈值的分析给出了控制丙肝传播的措施建议。数值模拟验证了结果的正确性,其结果对具有时滞和治疗的丙肝模型的研究是有意义的,可为减少丙肝的流行提供新的思路。     

资源再生产品市场演化与价值实现的协调博弈分析

资源再生产品市场发育存在诸多障碍,只有生产者和消费者群体行动达成一致,才能促进市场完善。本文运用协调博弈方法,着眼于再生产品市场整体性演化,分析有限理性的生产者和消费者两个群体行为变化机理及其策略均衡。研究认为,自发市场中消费者群体的购买行为取决于再生品与非再生品的价值比较,而由于存在无代价"漂绿者",生产者群体趋于不生产再生品;在政府干预下对再生品生产进行补贴,且对进行"漂绿者"处罚,生产者才会整体趋于提供再生品。前者市场趋于萎缩,后者市场得以扩展。     

具有媒体饱和发生率的SIS时滞模型研究

为了研究媒体报道对传染病动力学性态的影响,通过建立疾病发生率受媒体报道影响的SIS数学模型,确定模型的基本再生数,证明平衡点的存在性以及地方病平衡点的唯一性,并证明无病平衡点的局部渐近稳定性和全局稳定性,以及地方病平衡点的局部渐近稳定性。引入时滞因子对模型进行深入研究,通过数值模拟验证了理论结果的正确性。研究结果表明:当参数满足一定条件时,在地方病平衡点会产生Hopf分支。具有媒体饱和发生率的SIS时滞模型的研究结果,阐释了媒体报道对疾病传播的影响,丰富了饱和发生率的传染病模型结果,为有效实施疾病防控提供了理论依据。     

具有交叉感染的2种菌株对逼近模型分析

为了研究具有一般接触率和用于治疗的SIS对逼近模型及其动力学性质,针对2种菌株是否可以独立生存,建立了一个在规则网络上2种菌株有交叉感染的SIS对逼近传染病模型。根据二项分布,利用节点的状态相关系数得到一个12维系统,计算出模型的基本再生数,得出无病平衡点的局部稳定性,进而获得了无病平衡点不稳定的阀值。通过理论分析和数值模拟得出模型的无病平衡点无条件存在,即不稳定。在研究了2种菌株独立存在以及共同生存的条件后,可以看出2种菌株可以独立生存,也可以相互感染。高维(12维)系统的引入,使得对逼近模型既能模拟疾病的传播机制又能捕捉到疾病传播所在种群的网络结构,因此将对逼近模型应用到多菌株疾病的传播中具有一定价值。     

提升泵对三甘醇损耗影响的研究

三甘醇循环提升泵作为海上石油平台三甘醇再生系统的核心设备之一,对三甘醇再生系统的稳定运行起到关键性作用,某海上油气田天然气三甘醇再生系统拥有两种类型三甘醇循环提升泵,一种是柱塞泵,一种是能量泵。以柱塞泵和能量泵为研究对象,通过三甘醇损耗量差异分析,探索不同类型的提升泵与三甘醇损耗之间的具体关系,研究发现在使用能量泵后三甘醇损耗量明显上升。文章通过分析循环提升泵种类对三甘醇损耗量的影响,提出了合理的控制措施,为降低三甘醇的损耗量、整体提升三甘醇系统的高效稳定运行和天然气海管的安全外输提供重要保证。     

齿轮常见故障教学实践研究

齿轮失效的基本原因是齿轮磨损、点蚀、折断等,当工作应力超过最大允许应力时,齿轮通常会失效。分析由于应力集中引起的轮齿疲劳失效的类型,结合教学实践进行阐释并提出针对齿轮常见故障的课程讲授方式及教学创新。     

基于界面等效模型的再生混凝土基面力元分析

从细观角度分析再生混凝土的力学特性,以往都是将再生混凝土视为由骨料、新砂浆、新界面、老砂浆、老界面五相介质组成的复合材料来分析,为了简化这种常规五相再生混凝土模型,提出了基于界面等效模型的再生混凝土基面力元分析方法。首先运用三相球理论模型将再生混凝土中的老砂浆、新界面、老界面三相介质等效成一种介质,得到三相介质的再生混凝土界面等效模型;然后利用势能原理的基面力元法编制出损伤基面力元程序,对不同尺寸的再生混凝土试块进行单轴拉伸试验模拟。给出了应力-应变曲线及破坏过程图,并与普通五相模型进行了对比,两种曲线基本吻合。因此,等效模型可以代替普通五相模型,从而简化多相再生混凝土的损伤分析,提高模拟效率。     

电厂树脂再生废水处理的探讨

离子交换器是电厂水处理的重要技术设备,可对电厂的水资源进行科学有效的处理,且经济效益较好。树脂再生废水处理是电厂水资源处理的一项重要内容,主要包含有一级除盐再生废水、混床再生废水、凝结水精处理高速混床再生废水等。文章针对电厂树脂再生废水处理进行研究与分析。     

油气长输管道外腐蚀维护风险缓解程度模型

对危害油气长输管道安全性的因数进行分析,通过故障树分析法,找出了导致管道外腐蚀穿孔破坏的31种影响因素,确定了各影响因素的逻辑关系,建立了故障树最小割集.通过专家主观评判对各基本事件的失效情况进行分析,将专家自然语言通过模糊数学的方法转换为模糊数,然后采用左右模糊排序法将[0,1]区间的模糊数转换位模糊失效概率值.针对危害管道的失效因素,采取现行比较常用的外腐蚀管道维护方法和对基本事件进行安全整改,然后聘请专家对管道维护前后的情况进行评判,采用所建立的计算基本事件失效概率值方法和所建立的最小割集,计算出外腐蚀管道维护前后失效概率,表明采取有针对性的维修和维护措施,管道的失效概率将会明显减低,降低了该管段的风险值.     

再生麻纤维抗菌性研究

再生麻纤维是一种新型的再生纤维素纤维。针对目前对该纤维具有抗菌性的报道,采用定性和定量2种方法分别对纤维、经过漂白整理后的纤维、染色后的纯纺织物进行了抗菌性试验,结果表明再生麻纤维的抗菌性对不同的菌种有选择性,经过漂白染色后的再生麻纤维及其织物对于某种细菌也具有抑制效果。     

Interlocking of information systems for international supply and demand chains management

This paper is concerned with coordination aspects of supply chain management and, in particular, investigates setup coordination between two and three stages of a supply chain. The problem arises from a real application in the production chain of a kitchen furniture plant. In different stages of the plant, items are grouped according to different attributes. A setup is required in a stage when the new batch has a different level of attribute from the previous one. Two objectives are considered, i.e., minimizing the total number of setups and minimizing the maximum number of setups of the stages. The problem is to determine a sequence of batches in search for Pareto-optimal solutions with respect to the two objectives. Several metaheuristics, including genetic algorithm, simulated annealing, and iterated local search (ILS) have been proposed for the two-stage problem. In this paper, we develop a constructive heuristic, which combines a least flexibility first principle and a greedy search, for the two- and three-stage problems. Computational results show that the proposed heuristic performs significantly better than the genetic algorithm and simulated annealing. Although the proposed heuristic is inferior to the ILS, which employs two constructive initial solution heuristic, for the two-stage problem, it can be easily extended to the three-stage problem.     

光谱颜色复制模型概述

利用光谱复制技术提高颜色复制精度,减少同色异谱现象,是目前颜色高保真复制方法研究的一个主流方向。本文总结回顾了各经典光谱模型,并对打印机适用的基于回归的经典光谱模型和基于物理过程的关键光谱模型进行介绍。其中打印机适用的基于回归的经典光谱模型包括适用于单色打印机的MmTay-Davies模型、适用于网目调多色印刷的Neugebauer模型、添加n值优化的Yule-Nielsen光谱反射率模型、Clapper-Yule光谱反射率模型、细胞化Neugebauer模型、细胞化Yule-Nielsen光谱模型、YNSN光谱模型以及细胞化YNSN模型。通过控制模型中的各可变参数,不断优化模型,可提高光谱颜色复制的精度。     

Piecewise procurement of a large-scale project

This paper studies the optimal piecewise procurement of a large-scale project. In the unique Markov Perfect Equilibrium (MPE) of the dynamic procurement game, it is found that (1) unlike the static setting, the procurer's optimal strategy depends on the number of suppliers and more importantly, it is nonmonotonic. As one more supplier participates in the procurement auction, the procurer softens competition in the initial stages by including more cost “types” while increasing competition in the mature stages; (2) this, in turn, implies that existing suppliers might favor participation of additional suppliers; (3) absent scheduling and/or resource constraints, the procurer prefers to procure the project as one piece if the suppliers' technology exhibits constant or increasing returns, and no additional suppliers are enticed to bid; and (4) the optimal dynamic mechanism can be easily implemented via a sequence of dominant strategy auctions of the Vickrey type.     

Analyzing business relationships and distinguishing different interaction levels

Over the years, there have been a large number of attempts to understand relationships in industrial markets. However, even if relationships are built up on the basis of series of interactions, these studies have not offered systematic categorization of different types of relationship interactions. The present article proposes a refined conceptualization for identifying different types of relationship interaction units, labeled interaction levels, ranging from a single exchange to a relationship portfolio. Compared to the current use of two interaction levels in relationship studies, the proposed conceptualization allows a more elaborate analysis of single relationships and better comparisons of different relationships.     

基于隔离和免疫的蠕虫传播模型及稳定性分析

网络蠕虫已经对网络基础设施和因特网服务造成了巨大的影响,为有效防御蠕虫病毒的入侵,提出了基于隔离和免疫的蠕虫传播SEIQV模型。利用SEIQV模型,得到了蠕虫是否灭绝的阈值,并从理论上证明了模型在无感染平衡点保持全局稳定性,在地方病平衡点保持局部稳定性,同时分析了其他参数对模型的影响,为蠕虫病毒的控制和预防提供了理论基础。     

Optimal organization in a sequential investment problem with the principal's cancellation option

This paper considers a two-stage sequential investment problem where the principal wishes to cancel the project if it fails in the first stage. Suppose that only the first-stage agent can observe the outcome in the first stage. There are two organizational forms to choose from: integration, where a single agent is in charge of investments in two stages; and separation, where two different agents are in charge of the two stages. Integration gives rise to a smaller wage cost of inducing high effort in both stages; however, in order to obtain the correct information to cancel the project, separation may have some advantage in terms of saving the information rent. We show that when the effort cost in the first stage is sufficiently small, the principal prefers separation because the first-stage agent has less incentive to lie about the outcome.     

丙型肝炎的治疗与药物预防进展

介绍了丙型肝炎的感染与发病以及对人体的危害 ,目前对 HCV感染的治疗包括IFN,IFN与三唑核苷、IFN与聚乙二醇 3种药物治疗方法 ,也介绍了重组 HCV蛋白质疫苗和 DNA疫苗的发展。     

Removing the fuzziness from the fuzzy front-end of service innovations through customer interactions

Customer interaction in new service development has a positive impact on the performance of new services. In addition, prior studies recognize the importance of the fuzzy front-end stages of new service development. Yet, the researchers have not taken the next step to explore the relationship between these two key areas of service innovation. To address this critique of the literature, the process of customer interaction in the fuzzy front-end of new service development is investigated by conducting a rigorous qualitative field research involving 26 financial services firms. The findings suggest that the fuzzy front-end can be much less ‘fuzzy’ if customers are involved in the front-end stages of new service development.     

Asymmetric customer–supplier relationship development in Taiwanese electronics firms

The purpose of this paper is to analyse the relationship development stages of asymmetric customer–supplier relationships. The structure of relationships between larger customers and smaller suppliers has been the focus of a number of studies in IMP (Industrial Marketing and Purchasing Group) research. But, there is a paucity of research that examines development stages in relationships where a difference in size between the parties exists. The paper links the characteristics of asymmetric customer–supplier relationships and the relationship development stages through a literature review. The findings from a set of five in-depth case studies of asymmetric customer–supplier relationships in the Taiwanese electronics industry are presented. The case studies involved 50 semi-structured interviews with customer and supplier executives and, in addition, multiple observations of customer–supplier interactions within each case study. Individual and cross-case analysis was conducted to examine the links between the characteristics of asymmetric customer–supplier relationships and relationship development stages. The findings revealed that asymmetric customer–supplier relationships in the Taiwanese electronics industry were very unbalanced and vulnerable in the exploratory stage of development. In the developing stage relationships were more likely to develop if suppliers and customers mirrored each other's behaviour and echoed each other's priorities. In the stable stage suppliers and customers worked on shared and balanced contributions to the relationship. The paper contributes to the understanding of how smaller suppliers and larger customers can identify and develop key sets of relationship characteristics through the exploratory, developing and stable stages of asymmetric relationship development from both customer and supplier perspectives.