Determining best practice production in an aluminium smelter involving sub-processes based substantially on tacit knowledge: an application of Communities of Practice

This paper considers the difficulties associated with a production process that contains a sub-process that is not fully understood and for which data for many parameters are only able to be approximately obtained. The aluminium smelting industry epitomizes such a situation. Here, the critical sub-process that exemplifies these difficulties is the actual heart of the smelter, the electrolytic processing of alumina. This sub-process of aluminium production is at best ‘fuzzy’ and relies on the smelter operators to use their experience and tacit knowledge on a day-to-day basis, that is, the sub-process involves ‘alchemy’. In this paper, this is referred to as the tacit knowledge problem. The impact of such sub-processes on production is significant and the development of a methodology that will lead to a reduced reliance on uncertain alchemy associated with them, highly beneficial. The role of Communities of Practice in finding a solution to the tacit knowledge problem is discussed together with its integration into a mixed-mode model for the determination of best practice production for the smelter.     

Diversity and Popularity in Organizations and Communities

This paper examines social groupings whose structure depends only on the distribution of ability to attract attention. When people‘s attention is a scarce resource, those individuals who are rated highest by a large number of other individuals will have to ration their attention, resulting in constraints on the social structure of the group. The incidence of popular individuals by that definition reflects the extent to which individuals agree on who their highest-rated colleague is. We propose three basic distributions or ways to generate the matrix of perceived ability so as to yield popularity profiles that can be parametrically adjusted to match observations. We demonstrate that each of these assumption sets leads to a slightly different correlation between the value of the assumption‘s parameter and the set of observable popularity patterns. Since popularity, in real life, often determines such things as power, centrality, over-utilization and perhaps reduced accessibility, having more realistic ways of representing it is important for modeling and understanding virtual organizations and communities.     

Asynchronous Richardson iterations: theory and practice

Numerical Algorithms - We consider asynchronous versions of the first- and second-order Richardson methods for solving linear systems of equations. These methods depend on parameters whose values...     

University−Urban High School Partnership: Math and Science Professional Learning Communities

This study focused on science and math professional learning communities (PLCs) that were implemented through a university‐urban high school partnership. These PLCs were part of mandated school‐wide, content‐based PLCs implemented as part of the reform efforts initiated in an urban school to address the school's failure to meet Adequate Yearly Progress (AYP) for four years consecutively and low graduation rate (less than 25%) for male students. The key issues were (a) students had continually earned low test scores; (b) there was continuous principal turnover; (c) faculty morale was at an all‐time low, and the quality of teaching was very poor; and (d) the students were not effectively disciplined. The study examined the impact that university faculty‐led mandated PLCs have on teachers' practices and students' learning and achievement. Analysis of data revealed practices that were effective in developing and implementing these successful math and science PLCs. Three themes emerged: ethics of care, teacher agency, and aesthetics of professional interactions. Each theme contained key features that appeared to contribute to the implementation of a successful PLC.     

Forecasting practice: organisational issues

Although many surveys have been conducted on forecasting practice, the majority of surveys have investigated the utilisation of forecasting methods and relatively few have studied the role of forecasting in changing organisational structures. The aim of this paper is to address this issue by expanding on earlier case studies which suggested the need for a re-location of the forecasting function within the organisation. Current research has shown how the role of forecasting has changed as organisations adapt to meet the business needs of their customers. The evidence reported in this paper was gathered by surveys and structured interviews carried out in the electronics and financial industries in Scotland.     

Historical evolution and mathematical models: A sociocultural algorithm

Though there are a lot of approaches to the problem of sociocultural evolution most of them are only one-sided, i.e., they deal only with either social or cultural processes. With few exceptions they are also only informal theories with no formal rigour. In this article we propose a theoretical model which considers both sides of the problem, that is the mutual interdependence of the evolution of social structures and of the culture of a society. A mathematical model, the sociocultural algorithm (SCA), based on these theoretical considerations maps several of the dynamic characteristics of sociocultural evolution, suggesting that universal principles underlie the dynamics of historical evolution.     

小区开放对道路通行的影响

介绍2016年"高教社杯"全国大学生数学建模竞赛B题"小区开放对道路通行的影响"的基本建模思路,并就此题参赛论文的总体情况作一概述。     

Intra-organizational Networks and Performance: A Review

Intra-organizational network research had its first heyday during the empirical revolution in social sciences before World War II when it discovered the informal group within the formal organization. These studies comment on the classic sociological idea of bureaucracy being the optimal organization. Later relational interest within organizational studies gave way to comparative studies on the quantifiable formal features of organizations. There has been a resurgence in intra-organizational networks studies recently as the conviction grows that they are critical to organizational and individual performance. Along with methodological improvements, the theoretical emphasis has shifted from networks as a constraining force to a conceptualization that sees them as providing opportunities and finally, as social capital. Because of this shift it has become necessary not only to explain the differences between networks but also their outcomes, that is, their performance. It also implies that internal and external networks should no longer be treated separately.Research on differences between intra-organizational networks centers on the influence of the formal organization, organizational demography, technology and environment. Studies on outcomes deal with diffusion and adaptation of innovation; the utilization of human capital; recruitment, absenteeism and turnover; work stress and job satisfaction; equity; power; information efficiency; collective decision making; mobilization for and outcomes of conflicts; social control; profit and survival of firms and individual performance.Of all the difficulties that are associated with intra-organizational network research, problems of access to organizations and incomparability of research findings seem to be the most serious. Nevertheless, future research should concentrate on mechanisms that make networks productive, while taking into account the difficulties of measuring performance within organizations, such as the performance paradox and the halo-effect.     

Manufacturing planning and control: The evolution of MRP and JIT integration

Material Requirements Planning (MRP) and Just-in-Time (JIT) system are directed toward planning and controlling the important characteristics of material flow: how much of what materials flow and when. Since the material flow is at the heart of the manufacturing firm, MRP and JHT are the powerful management tools that could determine the success or failure of an entire manufacturing system. One of the strongest debates in manufacturing has been centered on the performance comparison and compatibility of JIT production system to the existing MRP. The primary intent of this research is to provide an overview of the manufacturing planning and control environment associated with MRP and JIT. Classifying the existing MRP/JIT comparison and integration literature, two different perspectives on MRP/JIT are discussed, and future research area is proposed based on the taxonomy.     

Drawdown: from practice to theory and back again

Maximum drawdown, the largest cumulative loss from peak to trough, is one of the most widely used indicators of risk in the fund management industry, but one of the least developed in the context of measures of risk. We formalize drawdown risk as Conditional Expected Drawdown (CED), which is the tail mean of maximum drawdown distributions. We show that CED is a degree one positive homogenous risk measure, so that it can be linearly attributed to factors; and convex, so that it can be used in quantitative optimization. We empirically explore the differences in risk attributions based on CED, Expected Shortfall (ES) and volatility. An important feature of CED is its sensitivity to serial correlation. In an empirical study that fits AR(1) models to US Equity and US Bonds, we find substantially higher correlation between the autoregressive parameter and CED than with ES or with volatility.     

Placenticeras: evolution of a task

We study a sequence of concrete case examples, anchored to a single image (of a fossil shell) to explore the complexity of building mathematical models in compelling realistic situations. The case examples are drawn from work with calculus undergraduates, and also dance majors from an experimental mathematics course who built evolving spiral forms in choreographic projects. The exposition is narrative, in the sense that it emphasizes, case by case, the evolution of the authors’ thinking in the course of extended conversations and collaborations with students over several years.     

Connected components and evolution of random graphs: an algebraic approach

Questions about a graph’s connected components are answered by studying appropriate powers of a special “adjacency matrix” constructed with entries in a commutative algebra whose generators are idempotent. The approach is then applied to the Erd?s–Rényi model of sequences of random graphs. Developed herein is a method of encoding the relevant information from graph processes into a “second quantization” operator and using tools of quantum probability and infinite-dimensional analysis to derive formulas that reveal the exact values of quantities that otherwise can only be approximated. In particular, the expected size of a maximal connected component, the probability of existence of a component of particular size, and the expected number of spanning trees in a random graph are obtained.     

The evolution of convention: Conformity and innovation in task-oriented networks

The individual choice between conformity and innovation within task-oriented collectivities is presented as a social dilemma. Adaptive, network-embedded actors are seen to modify their propensities to conform or innovate retrospectively, based on performance differences between the individual and task group levels. A computational framework, based on simulation techniques and algorithmic complexity theory, is advanced to investigate the impact of antecedent structural conditions on innovative behavior and the effect that such behavior has on the evolution of patterns of interaction (conventions) and efficiency. Findings indicate that the dynamics of innovation differ dramatically based on the complexity of tasks faced by actors. When simple tasks are addressed, innovative behaviors have a destabilizing effect on social conventions and are clearly linked to contextual factors. When complex tasks are involved, commitment to innovation may actually help reinforce conventions and is not tied to structural antecedents.Department of Sociology, Stanford University