Combining Data Mining and Discrete Event Simulation for a value-added view of a hospital emergency department

While simulation models have furthered understanding of the operations of emergency departments (EDs) and the dynamics of the ED within the healthcare system, they only model patient treatment implicitly, tracing the paths patients follow through the ED. By identifying the core patient treatments provided by the ED and incorporating them into a Discrete Event Simulation model, this paper provides insight into the complex relationship between patient urgency, treatment and disposal, and the occurrence of queues for treatment. The essential characteristics of the presented model are used to indicate a generally applicable methodology for identifying bottlenecks in the interface between an ED and a hospital ward.     

Conceptual modelling for simulation Part I: definition and requirements

Conceptual modelling is probably the most important aspect of a simulation study. It is also the most difficult and least understood. Over 40 years of simulation research and practice have provided only limited information on how to go about designing a simulation conceptual model. This paper, the first of two, discusses the meaning of conceptual modelling and the requirements of a conceptual model. Founded on existing literature, a definition of a conceptual model is provided. Four requirements of a conceptual model are described: validity, credibility, utility and feasibility. The need to develop the simplest model possible is also discussed. Owing to a paucity of advice on how to design a conceptual model, the need for a conceptual modelling framework is proposed. Built on the foundations laid in this paper, a conceptual modelling framework is described in the paper that follows.     

A Markovian queueing model for ambulance offload delays

Ambulance offload delays are a growing concern for health care providers in many countries. Offload delays occur when ambulance paramedics arriving at a hospital Emergency Department (ED) cannot transfer patient care to staff in the ED immediately. This is typically caused by overcrowding in the ED. Using queueing theory, we model the interface between a regional Emergency Medical Services (EMS) provider and multiple EDs that serve both ambulance and walk-in patients. We introduce Markov chain models for the system and solve for the steady state probability distributions of queue lengths and waiting times using matrix-analytic methods. We develop several algorithms for computing performance measures for the system, particularly the offload delays for ambulance patients. Using these algorithms, we analyze several three-hospital systems and assess the impact of system resources on offload delays. In addition, simulation is used to validate model assumptions.     

Modelling a Solid-Waste Processing System by Discrete Event Simulation

This paper describes a discrete event simulation model for a solid-waste processing system which is to be installed in Zagreb, Croatia. The conceptual model was developed by activity cycle diagrams, and the computer model was developed using the program generation software package VS6. This paper describes the validation and verification of such a model, the design of simulation experiments and the selection of the system's configuration.     

基于体系工程与物流均衡的C2M服务制造物流体系结构模型

C2M服务制造是基于以顾客为中心的C2M(Customer to Manufacture)商业模式,是在服务型制造及生产性服务业为基础上而形成的一种新型产业模式。C2M服务制造要求构建合理的物流体系,而构建物流体系结构已经成为该研究的关键基础。本文基于体系工程和物流均衡理论,通过建立物流体系以解决C(客户)端与M(制造)端的短链式互联问题,在分析C2M服务制造物流体系特征和资源要素的基础上,给出了C2M服务制造物流体系的概念模型和结构模型,并运用价值函数分析体系状态是否优化,从而达到C端与M端快速互联的目标,进而解决了物流体系结构模型在C2M服务制造物流体系构建中的应用问题。     

Modeling fuzzy information in UML class diagrams and object-oriented database models

Conceptual data modeling has become essential for non-traditional application areas. Some conceptual data models have been proposed as tools for database design and object-oriented database modeling. Information in real-world applications is often vague or ambiguous. Currently, a little research is underway on modeling the imprecision and uncertainty in conceptual data modeling and the conceptual design of fuzzy databases. The unified modeling language (UML) is a set of object-oriented modeling notations and a standard of the object management group (OMG) with applications to many areas of software engineering and knowledge engineering, increasingly including data modeling. This paper introduces different levels of fuzziness into the class of UML and presents the corresponding graphical representations, with the result that UML class diagrams may model fuzzy information. The fuzzy UML data model is also formally mapped into the fuzzy object-oriented database model.     

Model development in discrete-event simulation and system dynamics: An empirical study of expert modellers

An empirical study comparing the model development process followed by experts in discrete-event simulation (DES) and system dynamics (SD) modelling is undertaken. verbal protocol analysis (VPA) is used to study the modelling process followed by ten expert modellers (5 SD and 5 DES). Participants are asked to build simulation models based on a case study and to think aloud while modelling. The generated verbal protocols are divided into seven modelling topics: problem structuring, conceptual modelling, data inputs, model coding, verification & validation, results & experimentation and implementation and then analyzed. Our results suggest that all modellers switch between modelling topics, however DES modellers follow a more linear progression. DES modellers focus significantly more on model coding and verification & validation, whereas SD modellers on conceptual modelling. Observations are made revealing some interesting differences in the way the two groups of modellers tackle the case. This paper contributes towards the comparison of DES and SD.     

Product life cycle analysis: a goal programming approach

This paper considers the role of Life-Cycle Costing (LCC), Time-Based Competition (TBC), and other relevant goals at the three planning-horizon levels of strategic, intermediate, and tactical with respect to time and cost of products to market in a concurrent engineering environment. A conceptual framework has been developed in which the general areas of LCC and TBC are delineated. Based on the conceptual framework, the specific components of LCC and TBC at each level of planning are developed and presented. Subsequently, a Preemptive Goal Programming (PGP) model is developed. This model uses the components of LCC, TBC, and other relevant goals as the decision variables. Then, a case study of a company that has developed LCC and TBC is considered. The PGP model is then applied to the company's operations by using the actual data obtained from the company in order to capture the essence of the conceptual framework. This example explains and validates the PGP model in practice and provides managerial implications of the solution. Finally, a set of conclusions and an assessment of the results are presented.     

Environmental Mapping of the European Community: A Review of the Proposed Method

The EEC Commission is currently developing a system of environmental classification and mapping as an aid to regional planning in Europe. This paper describes the proposed system and discusses the method and its objectives in relation to experience gained in applying the proposals in South Yorkshire. It is argued that although the objectives of the project are laudable, the approach which has been adopted may be unrealistic due to deficiencies in the available data, lack of knowledge about the environmental systems under consideration, and some conceptual and technical shortcomings in the proposed model.     

Hopf bifurcation in a conceptual climate model with ice–albedo and precipitation–temperature feedbacks

In this paper we analyse a dynamical system based on the so-called KCG (Källén, Crafoord, Ghil) conceptual climate model. This model describes an evolution of the globally averaged temperature and the average extent of the ice sheets. In the nondimensional form the equations can be simplified facilitating the subsequent analysis. We consider the limiting case of a stationary snow line for which the phase plane can be completely analysed and the type of each critical point can be determined. One of them can exhibit the Hopf bifurcation and we find sufficient conditions for its existence. Those, in turn, have a straightforward physical meaning and indicate that the model predicts internal oscillations of the climate. Using the typical real-world values of appearing parameters we conclude that the obtained results are in the same ballpark as the conditions on our planet during the quaternary ice ages. Our analysis is a rigorous justification of a generalization of some previous results by KCG and other authors.     

Developing a Conceptual Model of STEAM Teaching Practices

STEAM, where the “A” represents arts and humanities, is considered a transdisciplinary learning process that has the potential to increase diverse participation in science, technology, engineering, and math (STEM) fields. However, a well‐defined conceptual model that clearly articulates essential components of the STEAM approach is needed to conduct empirical research on STEAM's efficacy–in particular, the teaching content that should be considered when enacting STEAM teaching practices. This paper proposes a conceptual model of STEAM, providing educators with the opportunity to teach effectively using transdisciplinary inquiry. The instructional content domain of the model includes problem‐based delivery, discipline integration, and problem‐solving skills.     

Crisis in complex social systems: A social theory view illustrated with the chilean case

The article argues that crises are a distinctive feature of complex social systems. A quest for connectivity of communication leads to increase systems' own robustness by constantly producing further connections. When some of these connections have been successful in recent operations, the system tends to reproduce the emergent pattern, thereby engaging in a non‐reflexive, repetitive escalation of more of the same communication. This compulsive growth of systemic communication in crisis processes, or logic of excess, resembles the dynamic of self‐organized criticality. Accordingly, we first construct the conceptual foundations of our approach. Second, we present three core assumptions related to the generative mechanism of social crises, their temporal transitions (incubation, contagion, restructuring), and the suitable modeling techniques to represent them. Third, we illustrate the conceptual approach with a percolation model of the crisis in Chilean education system. © 2016 Wiley Periodicals, Inc. Complexity 21: 13–23, 2016     

基于国家安全视角的文化软实力测度模型及实证分析研究

在对文化软实力量化研究现状分析的基础上,从国家安全视角出发提出了文化软实力概念模型,通过对各维度凝炼构建了基于国家安全视角的6维度、25个二级指标的文化软实力测评指标体系,通过综合运用专家访谈法和层次分析法得到指标权重,综合运用问卷调查法和模糊综合评判法得到中国文化软实力测评结果.实证表明,测评结果和理论分析基本一致,研究方法具有较高的科学性和可信度.     

Some Systems Aspects of Strategic Planning

This paper is concerned with the strategic planning process and the contribution that analysis can make to it. It develops a conceptual model of the strategic planning process based on the traditional control system model and identifies a number of basic elements of the process. Four groups of analytical tools are presented and their relevance to the planning process discussed. It is suggested that tools from the different groups may be used concurrently at different parts of the process, although the use of analytical tools in some parts of the planning process is not well established. Finally the role of the analyst in the overall planning process is discussed.     

洪灾综合风险分析方法讨论(Ⅱ)——基于集对分析理论

对洪灾系统作综合风险研究,已是防洪减灾理论发展的一大趋势.在洪灾风险的同异反综合分析方法(概念模型)的基础上,以不确定性系数i对风险的影响为切入点,并进行适当的扩展与变换,将同异反综合分析方法进一步深入,建立了洪灾综合风险分析的模拟模型框架,初步得到了洪灾综合风险分析的可行途径.     

A participative and facilitative conceptual modelling framework for discrete event simulation studies in healthcare

Existing approaches to conceptual modelling (CM) in discrete-event simulation do not formally support the participation of a group of stakeholders. Simulation in healthcare can benefit from stakeholder participation as it makes possible to share multiple views and tacit knowledge from different parts of the system. We put forward a framework tailored to healthcare that supports the interaction of simulation modellers with a group of stakeholders to arrive at a common conceptual model. The framework incorporates two facilitated workshops. It consists of a package including: three key stages and sub-stages; activities and guidance; tools and prescribed outputs. The CM framework is tested in a real case study of an obesity system. The benefits of using this framework in healthcare studies and more widely in simulation are discussed. The paper also considers how the framework meets the CM requirements.     

Negotiation support systems: A multi-criteria and multi-agent approach

This research concerns the development of an Negotiation Support Systems (NSS) based on a multi-criteria conceptual framework of the negotiation and developed according to a multi-agent architecture from Distributed Artificial Intelligence (DAI). A first prototype of such a system, NegocIAD, has already been developed [8], but the weakness of its assistance to the negotiation process have led us to revise the conceptual framework in order to define a more relevant assistance to the negotiation process. This paper presents this new conceptual framework defined in order to develop a new prototype. First, we point out the originality of our multi-criteria and multi-agent approach, the general architecture and the limitations of NegocIAD. Then we present the new multi-criteria conceptual framework mainly based on the definition and the use of projection plans (group Gaia plans) emerging from principal component analysis (PCA) already proposed in a single decision maker context in extension of the Promethee method. In the next part, we develop the possible levels of use of these plans during the negotiation process and the type of assistance provided to the mediator. This assistance is mainly based on the elaboration and the interpretation of group Gaia plans for which we propose a set of interpretation rules and the outline of a method to make use of these rules for a relevant support to the mediator in the management of the negotiation process. Finally, we conclude on the perspectives of our future researches and developments for the new generation of our prototype in a multi-agent architecture context.     

A DEA methodology to evaluate the impact of information asymmetry on the efficiency of not-for-profit organizations with an application to higher education in Brazil

This paper presents a conceptual framework and an analytical DEA model for evaluating the impact of information asymmetry on organizational efficiency. The framework uses concepts from agency theory to estimate the extent of moral hazard by comparing the objectives of the principal to those of the agent. The framework and model are useful in the analysis of both for-profit and not-for-profit organizations because DEA is applicable whether or not inputs and/or outputs are subject to pricing mechanisms. An illustration focusing on the Brazilian not-for-profit federal university system finds that the agency problem indeed exists for a subset of those institutions, indicating the desirability of improved incentive and control mechanisms on the part of the principal.     

A new algorithm for dual-rate systems frequency response computation in discrete control systems

This paper addresses an easy computation of the multiple components of the response to a sinusoidal input of a dual-rate linear time-invariant discrete system from the Bode diagram of LTI systems arising from a lifted representation. Based on those results, a generalized Bode diagram is suggested. Some new conclusions derived from this conceptual interpretation are introduced. This diagram provides a better insight in the frequency-response issues in multivariable control than the standard singular value decomposition of the lifted model. As an application, the output ripple suppression in a multirate control scheme is presented.     

On the role of bounds in stochastic linear programming

Stochastic linear programming (SLP) models involve multivariate integrals. Although in the discretely distributed case these integrals become sums they typically contain a large amount of terms. The purpose of this paper is twofold:On the one hand we discuss the usage of bounds concerning integrals for constructing SLP algorithms and secondly we point out the role of bounds-based algorithms for solving SLP problems. The conceptual considerations are demonstrated in the last section by computational results. The tests have been carried out by utilizing SLP-IOR, our model management system for SLP