A Study of Risk Relevance Reasoning Based on a Context Ontology of Railway Accidents

With the application of risk management and accident response in the railway domain, risk detection and prevention have become key research topics. Many dangers and associated risk sources must be considered in collaborative scenarios of heavy-haul railways. In these scenarios, (1) various risk sources are involved in different data sources, and context affects their occurrence, (2) the relationships between contexts and risk sources in the accident cause mechanism need to be explicitly defined, and (3) risk knowledge reasoning needs to integrate knowledge from multiple data sources to achieve comprehensive results. To express the association rules among core concepts, this article constructs two ontologies: The accident-risk ontology and the context ontology. Concept analysis is based on railway domain knowledge and accident analysis reports. To sustainably integrate knowledge, an integrated evolutionary model called scenario-risk-accident chain ontology (SRAC) is constructed by introducing new data sources. The SRAC is integrated through expert rules between the two ontologies, and its evolution process involves new knowledge through a new risk source database. After three versions of the upgrade process, potential risk sources can be mined and evaluated in specific contexts. To evaluate the risk source level, a long short-term memory (LSTM) neural network model is used to capture context and risk text features. A model comparison for different neural network structures is performed to find the optimal evaluation results. Finally, new concepts, such as risk source level, and new instances are updated in the context-aware risk knowledge reasoning framework.     

A local search approximation algorithm for a squared metric <Emphasis Type="Italic">k</Emphasis>-facility location problem

We consider a scheduling problem where machines need to be rented from the cloud in order to process jobs. There are two types of machines available which can be rented for machine-type dependent prices and for arbitrary durations. However, a machine-type dependent setup time is required before a machine is available for processing. Jobs arrive online over time, have deadlines and machine-type dependent sizes. The objective is to rent machines and schedule jobs so as to meet all deadlines while minimizing the rental cost. As we observe the slack of jobs to have a fundamental influence on the competitiveness, we parameterize instances by their (minimum) slack. An instance is called to have a slack of \(\beta \) if, for all jobs, the difference between the job’s release time and the latest point in time at which it needs to be started is at least \(\beta \). While for \(\beta < s\) no finite competitiveness is possible, our main result is an online algorithm for \(\beta = (1+\varepsilon )s\) with Open image in new window , where s denotes the largest setup time. Its competitiveness only depends on \(\varepsilon \) and the cost ratio of the machine types and is proven to be optimal up to a factor of Open image in new window .     

本土需求情景下破坏性创新的形成机理研究

 已有破坏性创新的研究大多在“破坏性创新已经出现”这个假设下，探讨企业如何应对破坏性创新的挑战，较少涉及破坏性创新的前因和过程。通过中国情景下本土需求实现破坏性创新的企业案例，剖析本土需求引发破坏性创新的形成机理，将有助于丰富破坏性创新形成前因的研究。        选取3家本土电动汽车企业作为研究对象，采用扎根理论研究方法的3阶段编码程序对案例进行剖析，解析后发国家情景下本土需求的构成要素，探究本土需求引致破坏性创新的概念框架，分别从本土需求的形成过程和异质性内涵以及本土需求与企业破坏性创新关系3个方面解读概念模型，最终给出本土需求引发破坏性创新的机理模型。        研究结果表明，①本土需求是由经济约束、政府规制、技术条件和社会文化条件4个主范畴构成，4个主范畴之间的交互作用创造了异质性需求条件，最终引发本土需求外在表现的独特性。②本土需求的4个主范畴对破坏性技术重构的作用点存在差异。经济约束、政府规制、技术条件和社会文化条件形成的约束条件产生技术结构性破坏，经济约束和政府规制形成的约束条件往往产生技术功能性破坏。③本土需求引发破坏性创新的过程分为破坏性技术重构型路径、价值网络重构型路径、技术衍生价值网络重构型路径、价值网络衍生技术重构型路径。        在理论上，研究结果为探讨不同范畴的本土需求与破坏性创新关系模式提供了理论分析框架，拓展了后发国家破坏性创新得以实现的基础和条件，描绘了后发企业基于本土需求构建破坏性创新的实现路径。在实践上，研究结果为后发国家的企业提供对策建议，使其能够有针对性的认知本土需求对破坏性创新的价值，并为后发国家政策有针对性地构造产业竞争规则提供理论支持。     

How rival partners compete based on cooperation?

Prior studies of coopetition have explained the what, how and why of firms cooperating with competitors. Among these, examining the how question as to the stream of coopetition dynamics is the most challenging theme. Previous research has focused much more on the cooperation side. Less attention has been paid to the competition side to reveal what happens to competition after the competitors have collaborated. This study sheds light on the issue of cooperation-based competition by answering the question: while cooperating with competitors, how do rival partners compete based on cooperation? Linking the competitive dynamics perspective to coopetition, we conducted a single-case study to analyse the competition between two leading competitors in the Taiwanese bicycle industry. We collected the reported issues pertaining to the competition in the European market and supported by in-depth interviews. The analysis leads us to develop three propositions and a conceptual framework for illustrating the cooperation-based competition and addressing how cooperation may influence competition in a coopetition relationship. This study provides new insights into a theoretical issue of cooperation-based competition. The case also provides management implications while taking a coopetition strategy.     

Power imbalance and value creation in joint ventures

Joint ventures (JVs) often do not create expected value due to power imbalance between partners. Despite the fact that JV partners are embedded in relational constraints, prior research has largely relied on economic reasoning by focusing on equity ownership difference between JV partners as the main source of power imbalance. We extend prior research to also consider important relational factors represented by repeated ties between partners and network openness, as well as institutional status difference and network status difference as two additional dimensions of power imbalance. Our findings indicate that ownership power imbalance by itself does not have a significant effect on value creation. However, value creation is facilitated when there is ownership power imbalance between partners with more repeated ties. In contrast, value creation may be hindered when JV partners with unequal ownership are embedded in more open interfirm alliance networks. Furthermore, value creation is facilitated if JV partners that have unequal ownership also have network status power imbalance in the same direction.     

Multi-start iterated tabu search for the minimum weight vertex cover problem

The minimum weight vertex cover problem (MWVCP) is one of the most popular combinatorial optimization problems with various real-world applications. Given an undirected graph where each vertex is weighted, the MWVCP is to find a subset of the vertices which cover all edges of the graph and has a minimum total weight of these vertices. In this paper, we propose a multi-start iterated tabu search algorithm (MS-ITS) to tackle MWVCP. By incorporating an effective tabu search method, MS-ITS exhibits several distinguishing features, including a novel neighborhood construction procedure and a fast evaluation strategy. Extensive experiments on the set of public benchmark instances show that the proposed heuristic is very competitive with the state-of-the-art algorithms in the literature.     

基于时变高阶矩波动模型的VaR与ES度量

金融波动性建模经历了从常数高阶矩到时变高阶矩的发展历程.文章扩展了现有的针对时变高阶矩波动模型风险测度效果的研究:首先,以沪深300指数和其它世界股市若干重要指数为例,通过采用“从简单模型到复杂模型”的估计步骤,实现对时变高阶矩波动模型的估计,进而运用Gram-Charlier扩展分布获得对VaR(value-at-risk)和ES(excepted shortfall)两种不同风险测度的计算值;然后,分别利用非条件覆盖检验(unconditional coverage test)和基于自举法(Bootstrap)的后验分析方法,实证对比了时变高阶矩和常数高阶矩两类模型的适用范围和精确程度.研究结果表明:就所考察的若干指数样本而言,时变高阶矩模型不仅能够较好地刻画金融价格波动的整体动力学特征,并且总体来讲,在市场风险测度准确性方面也要优于常数高阶矩波动模型.     

On the generalized multiway cut in trees problem

Given a tree $T = (V, E)$ with $n$ vertices and a collection of terminal sets $D = \{S_1, S_2, \ldots , S_c\}$ , where each $S_i$ is a subset of $V$ and $c$ is a constant, the generalized multiway cut in trees problem (GMWC(T)) asks to find a minimum size edge subset $E^{\prime } \subseteq E$ such that its removal from the tree separates all terminals in $S_i$ from each other for each terminal set $S_i$ . The GMWC(T) problem is a natural generalization of the classical multiway cut in trees problem, and has an implicit relation to the Densest $k$ -Subgraph problem. In this paper, we show that the GMWC(T) problem is fixed-parameter tractable by giving an $O(n^2 + 2^k)$ time algorithm, where $k$ is the size of an optimal solution, and the GMWC(T) problem is polynomial time solvable when the problem is restricted in paths.We also discuss some heuristics for the GMWC(T) problem     

供应链中的信息共享激励:动态模型

信息共享对促进整个供应链的绩效极为关键,但是供应链中的成员缺乏进行信息共享的激励。本文以一个两阶段的多任务委托-代理模型来研究供应链中的核心企业对其供应商进行供应活动和信息共享活动的最优激励问题,并用它来解释供应链中合作伙伴关系的持续改善过程。结果表明:供应商努力成本的边际替代率在信息共享以及正常供应活动的激励中起着关键性的作用。