Evaluating system change options and timing using the epoch syncopation framework

Complex engineering systems face many unknowns with respect to their operating contexts and time-varying stakeholder needs over their lifespan. A useful means for partitioning this problem is to consider a set of static snapshots of contexts with accompanying stakeholder needs over fixed periods of time, herein called “epochs.” Designs can be optimized towards delivering stakeholder utility in a specific epoch or across a variety of epochs. In order to consider the uncertain sequence of epochs experienced by a system, the Epoch Syncopation Framework (ESF) is introduced in this paper. This framework, using Monte Carlo analysis and Markov probability matrices, analyzes the execution of potential system “change mechanisms,” which alter a system over time to respond to epoch shifts. Through an analysis of design tradespaces, the ESF takes into account performance, schedule, cost, and uncertainty regarding experienced epoch shifts. The intended contributions of the ESF include a set of useful baseline designs, desirable change mechanisms, and strategies for executing change mechanisms across a system lifespan. The ESF is demonstrated through an application to an existing dataset containing designs for a “space tug” satellite including its set of potential epochs.Massachusetts Institute of Technology. Systems Engineering Advancement Research Initiativ

The Impact of Change on System of Systems Performance with an Application to Small and Medium Multihospital Systems

An entity that functions as a system of systems (SoS) is composed of multiple systems that individually provide various functions which collectively provide a holistic functional capability. It is complex in design and function and tends to become even more complex over time as it evolves and responds to both internal and external changes. These changes might be in the composition or in the interoperability among its system members. Since interoperability affects how well the members work as one system, managing it is critical to the performance of the SoS over its lifespan. In support of this goal, this dissertation, through research and analysis of small-medium hospital systems, develops a descriptive approach to assist management in determining the impact that changes in membership and interoperability of member systems might have on SoS performance. A modeling approach was used to assess SoS performance before and after changes. This model is part of an analysis framework called Tri-Ex that can be used by managers to evaluate proposed system changes. The procedures and techniques used are recommended for any future investigations into applicability for SoS performance in different domains; designing system structure with future capabilities in mind; and operational assessment during development

An integrated framework for the next generation of Risk-Informed Performance-Based Design approach used in Fire Safety Engineering

Review of decades of worldwide experience using standards, codes and guidelines related to performance-based fire protection design for buildings has identified shortcomings in the interpretation, application and implementation of the performance-based design process, wide variation in the resulting levels of performance achieved by such designs, and several opportunities to enhance the process. While others have highlighted shortcomings in the past, as well as some ideas to enhance the process, it is proposed that a more fundamental change is needed. First, the political and technical components of the process need to be clearly delineated to facilitate better analysis and decision-making within each component. Second, the process needs to be changed from one which focuses only on fire safety systems to one which views buildings, their occupants and their contents as integrated systems. In doing so, the activities associated with the normal operation of a building and how they might be impacted by the occurrence of a fire event become clearer, as do mitigation options which account for the behaviors and activities associated with normal use. To support these changes, a new framework for a risk-informed performance-based process for fire protection design is proposed: one which is better integrated than current processes, that treats a fire event as a disruptive event of a larger and more complex building-occupant system, and that provides more specific guidance for engineering analysis with the aim to achieve more complete and consistent analysis. This Ph.D. Dissertation outlines the challenges with the existing approaches, presents the building-occupant system paradigm, illustrates how viewing fire (or any other hazard) as a disruptive event within an holistic building-occupant system can benefit the overall performance of this system over its lifespan, and outlines a framework for a risk-informed performance-based process for fire protection design. Case studies are used to illustrate shortcomings in the existing processes and how the proposed process will address these. This Dissertation also includes a plan of action needed to establish guidelines to conduct each of the technical steps of the process and briefly introduces the future work about how this plan could be practically facilitated via a web-platform as a collaborative environment

The General Motor Ability Hypothesis: An old idea revisited

While specific motor abilities have become a popular explanation for motor performance, the older, alternate notion of a general motor ability should be revisited. Current theories lack consensus, and most motor assessment tools continue to derive a single composite score to represent motor capacity. In addition, results from elegant statistical procedures such as higher order factor analyses, cluster analyses, and Item Response Theory support a more global motor ability. We propose a contemporary model of general motor ability as a unidimensional construct that is emergent and fluid over an individual’s lifespan, influenced by both biological and environmental factors. In this article, we address the implications of this model for theory, practice, assessment, and research. Based on our hypothesis and Item Response Theory, our Lifespan Motor Ability Scale can identify motor assessment tasks that are relevant and important across varied phases of lifespan development

From the Hands of an Early Adopter's Avatar to Virtual Junkyards: Analysis of Virtual Goods' Lifetime Survival

One of the major questions in the study of economics, logistics, and business forecasting is the measurement and prediction of value creation, distribution, and lifetime in the form of goods. In "real" economies, a perfect model for the circulation of goods is impossible. However, virtual realities and economies pose a new frontier for the broad study of economics, since every good and transaction can be accurately tracked. Therefore, models that predict goods' circulation can be tested and confirmed before their introduction to "real life" and other scenarios. The present study is focused on the characteristics of early-stage adopters for virtual goods, and how they predict the lifespan of the goods. We employ machine learning and decision trees as the basis of our prediction models. Results provide evidence that the prediction of the lifespan of virtual objects is possible based just on data from early holders of those objects. Overall, communication and social activity are the main drivers for the effective propagation of virtual goods, and they are the most expected characteristics of early adopters.Comment: 28 page

Practitioner Perceptions of the A3 Method for Process Improvement in Health Care

The focus of this article is to present students’ perceptions of the recently developed A3 method, a structured problem-solving approach based on lean concepts and tools that have been adapted to the health care environment. The students were all employees of a large health care provider and were enrolled in a customized health care executive MBA Program. Each student was required to complete an individual A3 Project in order to improve a process at the department for which they worked. At the end of the semester the students presented their A3 projects to their peers who voted on the best projects. A survey measuring perceptions of the A3 method for problem solving in health care was administered and from it we present propositions for A3 implementation. These propositions are applicable both to health care practitioners and to academic researchers

A design framework for enabling sustainability in the clothing sector

This article discusses general strategies to enable environmental sustainability within the clothing sector, providing a framework for decision makers involved in the development of programs and policies for this sector. It initially revises the environmental impact of the clothing system and determines its key environmental sustainability priorities. The framework involves five evolutionary strategies for enabling sustainable consumption and production: 1) environmental improvement of flows throughout the supply chain; 2) environmental redesign of existing clothes; 3) design of new clothes intrinsically more sustainable; 4) design of cloth-service systems and 5) promoting life styles towards sufficient consumption. The practical implications of each strategy is analysed based on correspondent ex-post-facto case studies identified in Brazil, using data collected through literature review and desktop research

Hedonic Coalition Formation for Distributed Task Allocation among Wireless Agents

Autonomous wireless agents such as unmanned aerial vehicles or mobile base stations present a great potential for deployment in next-generation wireless networks. While current literature has been mainly focused on the use of agents within robotics or software applications, we propose a novel usage model for self-organizing agents suited to wireless networks. In the proposed model, a number of agents are required to collect data from several arbitrarily located tasks. Each task represents a queue of packets that require collection and subsequent wireless transmission by the agents to a central receiver. The problem is modeled as a hedonic coalition formation game between the agents and the tasks that interact in order to form disjoint coalitions. Each formed coalition is modeled as a polling system consisting of a number of agents which move between the different tasks present in the coalition, collect and transmit the packets. Within each coalition, some agents can also take the role of a relay for improving the packet success rate of the transmission. The proposed algorithm allows the tasks and the agents to take distributed decisions to join or leave a coalition, based on the achieved benefit in terms of effective throughput, and the cost in terms of delay. As a result of these decisions, the agents and tasks structure themselves into independent disjoint coalitions which constitute a Nash-stable network partition. Moreover, the proposed algorithm allows the agents and tasks to adapt the topology to environmental changes such as the arrival/removal of tasks or the mobility of the tasks. Simulation results show how the proposed algorithm improves the performance, in terms of average player (agent or task) payoff, of at least 30.26% (for a network of 5 agents with up to 25 tasks) relatively to a scheme that allocates nearby tasks equally among agents.Comment: to appear, IEEE Transactions on Mobile Computin