Joint chance-constrained staffing optimization in multi-skill call centers

This paper concerns the staffing optimization problem in multi-skill call centers. The objective is to find a minimal cost staffing solution while meeting a target level for the quality of service (QoS) to customers. We consider a staffing problem in which joint chance constraints are imposed on the QoS of the day. Our joint chance-constrained formulation is more rational capturing the correlation between different call types, as compared to separate chance-constrained versions considered in previous studies. We show that, in general, the probability functions in the joint-chance constraints display S-shaped curves, and the optimal solutions should belong to the concave regions of the curves. Thus, we propose an approach combining a heuristic phase to identify solutions lying in the concave part and a simulation-based cut generation phase to create outer-approximations of the probability functions. This allows us to find good staffing solutions satisfying the joint-chance constraints by simulation and linear programming. We test our formulation and algorithm using call center examples of up to 65 call types and 89 agent groups, which shows the benefits of our joint-chance constrained formulation and the advantage of our algorithm over standard ones.

     

帖木哥斡惕赤斤家族之盛衰

帖木哥斡惕赤斤是一代天骄成吉思汗最小的弟弟,处处受到兄长们的爱护和关照.特别是长兄成吉思汗对他更是备加关爱.他分得的领地之广,属民之多,为东道诸王之最.当成吉思汗出征时,委以重任,让他监国处理军政大事.然而盛气凌人的斡惕赤斤及其子孙,在蒙元时期几经叛乱,屡遭镇压.从而其势力日趋衰败,到明末清初很难寻觅到他们家族的踪影.     

Flood risk mapping and analysis using an integrated framework of machine learning models and analytic hierarchy process

In this study, a new approach of machine learning (ML) models integrated with the analytic hierarchy process (AHP) method was proposed to develop a holistic flood risk assessment map. Flood susceptibility maps were created using ML techniques. AHP was utilized to combine flood vulnerability and exposure criteria. We selected Quang Binh province of Vietnam as a case study and collected available data, including 696 flooding locations of historical flooding events in 2007, 2010, 2016, and 2020; and flood influencing factors of elevation, slope, curvature, flow direction, flow accumulation, distance from river, river density, land cover, geology, and rainfall. These data were used to construct training and testing datasets. The susceptibility models were validated and compared using statistical techniques. An integrated flood risk assessment framework was proposed to incorporate flood hazard (flood susceptibility), flood exposure (distance from river, land use, population density, and rainfall), and flood vulnerability (poverty rate, number of freshwater stations, road density, number of schools, and healthcare facilities). Model validation suggested that deep learning has the best performance of AUC = 0.984 compared with other ensemble models of MultiBoostAB Ensemble (0.958), Random SubSpace Ensemble (0.962), and credal decision tree (AUC = 0.918). The final flood risk map shows 5075 ha (0.63%) in extremely high risk, 47,955 ha (5.95%) in high-risk, 40,460 ha (5.02%) in medium risk, 431,908 ha (53.55%) in low risk areas, and 281,127 ha (34.86%) in very low risk. The present study highlights that the integration of ML models and AHP is a promising framework for mapping flood risks in flood-prone areas.     

河州何土司家族考略

何土司是明代在西北最早敕封的土司之一,对西北的政治、军事等都产生过重要影响,因为缺乏系统记载,学界对其一直知之不详。何土司在明初受封世袭指挥同知,一直到民国二十一年,方被废除。其统治时间之长,影响力之大,势力之强,在西北土司中也是首屈一指的。     

青海藏族阿柔部落兴衰史探析

阿柔是青海藏族土著游牧部落,自认为是山神之后代.明代蒙古族进入青海打破了藏族部落原有的分布格局,清廷对藏蒙分河而治成为两族争夺牧场与藏族部落北迁的直接原因.由于阿柔历代千户与各政治势力的巧妙周旋及其与寺院政、教功能的极致发挥,维护了部落利益,使其虽历经动荡与迁徙而未解体.从人类学视角看,藏传佛教的神山信仰形成了阿柔人崇尚神性的心理结构,迁徙的游牧生活反而加强了其族群意识,与蒙古族的频繁接触与联姻使其服饰与婚俗中糅合了蒙古族元素.     

藏传佛教世俗化研究中的几个理论问题探析

最近几年,中国的社会进入了一个转型时期,而处于这个时期的藏传佛教也由于各方面的原因所致,出现了许多新的变化.有的学者便以此为依据,提出藏传佛教的世俗化问题,并展开了大量的研究.本文试图对藏传佛教世俗化研究中遇到的几个理论问题作一深入探析,为藏传佛教世俗化研究提供一定的理论支持.     

吐蕃政权的传统军事思想初探

藏族自青藏高原上兴起之后,便开始了其四方征伐的历史.在长期的征战过程中,吐蕃政权逐渐形成了自己一套完整的军事理论,这就是吐蕃政权的传统军事思想.这些军事思想,体现的是古代藏民族对战争规律的理解,可以说是藏民族智慧的结晶.迄今为止,对吐蕃政权传统军事思想进行系统研究的文章尚不多见,文章试图对这一问题进行初步探索.     

What Makes Better Boards? A Closer Look at Diversity and Ownership

This study investigates the joint effect of corporate ownership and board of directors' diversity configurations on the success of strategic merger and acquisition (M&A) decisions. Board diversity is defined as the extent to which its demographic diversity as measured by the culture, nationality, gender and experience of its directors complements its statutory diversity. A theoretical framework linking ownership, board diversity and M&A strategic decision making is proposed and tested. Based on a sample of 289 M&A decisions undertaken by Canadian firms over the period 2000–2007, demographic diversity is found to have a clear and non‐linear effect on M&A performance while statutory diversity is of limited influence. Ownership is found to influence the effect of diversity, making the relation finer and more precise. This has practical implications. First, statutory diversity is not sufficient for well‐performing boards. Also, ownership is an important factor. The most advocated board diversity aimed at insuring the board's independence is not valid across all ownership configurations. From a public policy perspective, results provide support for the principles‐based approach in governance. Governance regimes should encourage the search for a balance between board diversity and the need for cohesion that best serves the firm's purpose and obligations.     

从婚俗文化看社会转型过程中藏族生育文化的变迁——以青海卓仓藏族为例

随着我国现代化转型过程的不断深入,地处经济社会欠发达地区的少数民族婚姻家庭文化在转型过程中发生了显著的变化。本文在田野调查的基础上,结合历史文献,通过对近代青海藏族婚俗文化意蕴的阐释,描述和分析了青海藏族在现代化转型时期婚俗文化对其生育文化变迁和重构的影响。