Robust Markowitz mean‐variance portfolio selection under ambiguous covariance matrix

This paper studies a robust continuous‐time Markowitz portfolio selection problem where the model uncertainty affects the covariance matrix of multiple risky assets. This problem is formulated into a min–max mean‐variance problem over a set of nondominated probability measures that is solved by a McKean–Vlasov dynamic programming approach, which allows us to characterize the solution in terms of a Bellman–Isaacs equation in the Wasserstein space of probability measures. We provide explicit solutions for the optimal robust portfolio strategies and illustrate our results in the case of uncertain volatilities and ambiguous correlation between two risky assets. We then derive the robust efficient frontier in closed form, and obtain a lower bound for the Sharpe ratio of any robust efficient portfolio strategy. Finally, we compare the performance of Sharpe ratios for a robust investor and for an investor with a misspecified model.     

Microfoundations of companies' dynamic capabilities for environmentally sustainable innovation: Case study insights from high‐tech innovation in science‐based companies

To achieve sustainable development, companies are increasingly putting an emphasis on the creation and the promotion of environmentally sustainable innovations. Environmentally sustainable innovation often involves a significant shift in a new strategic direction. This paper studies this shift from a dynamic capabilities perspective and aims to identify the microfoundations of science‐based companies' dynamic capabilities for high‐tech environmentally sustainable innovations. It investigates the development of high‐tech environmentally sustainable innovations in two distinctive science‐based companies. To scholars, this study provides an in‐depth process analysis, over time, of how and why microfoundations of dynamic capabilities influence the development of a science‐based company's high‐tech environmentally sustainable innovations. To practitioners in science‐based firms, this process study can function as a frame of reference, enabling the tailoring of a strategy for high‐tech environmentally sustainable innovation.     

舾装作业中考虑周期驱动的虚拟单元多阶段动态调度研究

多品种小批量离散型生产企业面临的大量不确定因素会干扰其生产的连续性,其中,船舶生产由于其技术与管理特点在此类生产中具有典型性.本文将以船舶舾装生产为例,在保证设备负荷均衡及资源利用率的基础上,研究该环节的虚拟单元调度问题,以提高企业的生产效率.文章以最小运输距离为目标,在充分考虑瓶颈资源约束的基础上,构建周期驱动下分割计划期的数学模型,并以结合任务分配和时间约束的混合蚁群算法求解.通过在某船厂舾装环节的应用发现,本文所提方法能够有效降低当前舾装各作业的平均完成时间,具备可行性.     

动液面谱减法滤波

动液面滤波是油井检测动液面的关键技术之一。文章利用谱减法处理油井动液面信号,消除背景噪声的影响,并改进谱减法应用到动液面滤波,取得较好的滤波效果,从而提高对液面反射波位置的辨识能力。     

动态井点降水在沈阳地铁东～滂区间盾构井的应用

地表管井动态降水在沈阳地铁东~滂区间盾构井的应用,降水井的间距、井深、泵型、下泵深度、水泵开启时间控制,通过动态调整以上参数完成盾构井基坑开挖施工。     

基于煤矿网络动态安全体系的安全账户管理效益分析

针对山西潞安集团潞宁煤业公司实际,在建立动态安全网络体系的基础上,构建安全账户管理体系,通过个人安全技能账户体系的构建,实行标准化考核,违章和事故大大降低,取得了预期的效益。     

综放工作面动态分次加架技术实践

针对一些不规则布置的综放工作面,介绍了当工作面长度变长时,采取不同的布置及加架方式的优缺点。这对于一些储量较少,地质条件复杂的矿井具有很好的借鉴意义。     

How an international ambidexterity strategy can address the paradox perspective on corporate sustainability: Evidence from Chinese emerging market multinationals

Corporate sustainability (CS) is receiving considerable attention from emerging market multinational enterprises (EMNEs), playing an important role in the globalized market. However, theoretical and empirical knowledge about how EMNEs address CS is still scant, and the relationship between internationalization and CS has not been widely explored. This study aims to fill this gap, evaluating the relationship between an international ambidexterity strategy and CS in EMNEs, which highlighted the paradox perspective. Then we develop three hypotheses in which we argue how the dynamic capabilities underpinning international ambidexterity could be considered a driver of CS in EMNEs. We test the developed hypotheses against data from 300 Chinese EMNEs obtained by a survey. Our results contribute to shape ambidextrous international strategies and to consider CS as a springboard for the strategic intent to systematically and recursively outperform global competition. Testing a measurement scale of international ambidexterity, we suggest structural ambidexterity as a strategic option of internationalization that allows the achievement of economic, social, and environmental sustainability objectives.     

A simple characterisation for sustained growth

This article considers an inter-temporal optimisation problem in a general form and gives conditions ensuring the convergence to infinity of the economy. These conditions can be easily verified and applied for a large class of problems in the literature. Some applications for different economies are given as illustrative examples.