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Transportation Networks. Optimality. Cost Functions. Deterministic User Equilibrium Assignment. Stochastic User Equilibrium Assignment. Trip Table Estimation. Network Reliability. Network Design. Conclusions. References. Index.

Transportation network analysis

This paper is written based on the need for Computerized Maintenance Management System's (CMMS) decision analysis capability to achieve world class status in maintenance management. Investigations indicate that decision analysis capability is often missing in existing CMMSs and collected data in the systems are not completely utilized. How to utilize the gathered data to provide guidelines for maintenance engineers and managers to make proper maintenance decisions has always been a crucial question. In order to provide decision support capability, the aim of this paper is to provide and examine three different decision making techniques which can be linked to CMMS and add value to collected data. This research has been conducted within a global project in a large manufacturing site in Sweden to provide a new maintenance management system for the company. The data from the main studies were collected through document analysis complemented by discussions with maintenance engineers and managers at the case company to verify the data. Methods including a Multiple Criteria Decision Making (MCDM) technique called TOPSIS, k-means clustering technique, and one decision making model borrowed from the literature were used. The results indicate the most appropriate maintenance decision for each of the selected machines/parts according to factors such as frequency of breakdowns, downtime, and cost of repairing. The paper concludes with a comparison of results obtained from the different decision making techniques and also a discussion on possible improvements needed to increase the capability of the maintenance decision making models.

Maintenance decision making, supported by computerized maintenance management system

This paper discusses a risk assessment approach to infrastructure technology planning aimed at improving power supply resiliency to natural disasters or other critical events. Cost as well as power supply availability are both fundamental decision factors considered in the study. The proposed planning process spans three phases during which the critical loads under study are subject to the effects of the extreme event: during the event, the immediate aftermath until potential infrastructure damage is repaired, and the long term aftermath until the load has recovered the same level existing before the critical event. The combined risk of these three phases is calculated considering likelihood of the critical event to occur, expected impact, and system vulnerability. This risk is then added to the system capital and normal operational costs to yield a lifetime cost that is used to compare technological options. Micro-grids are identified as a relevant technology with potential to achieve enhanced power supply during critical events. The analysis provides indications on how to better configure micro-grids in order to achieve high availability through diverse local distributed generation sources.

Technology Planning for Electric Power Supply in Critical Events Considering a Bulk Grid, Backup Power Plants, and Micro-Grids

Managing complex project process models with a process architecture framework

There are many references about the characteristics of a good requirement. But what is the process for developing clear, unambiguous requirements, and how do we know when we have defined the requirements successfully? This paper investigates the current state of the methodology for developing complex system requirements. Significant work has been accomplished over the last several years to describe requirements development and systems engineering. This paper identifies and investigates requirements development methodologies and techniques. ©2012 Wiley Periodicals, Inc. Syst Eng 16

Systems requirements engineering—State of the methodology

This paper presents a conceptual methodology for selecting existing systems to form candidate systems of systems (SoS) and selecting the preferred candidate SoS to provide a new capability. This methodology begins with SoS acquisition and mission requirements and selects the preferred SoS in six steps. Decision factors used for this purpose are selected based on their importance in providing and sustaining the required SoS capability. A new index of priority is introduced and utilized in this methodology to compare candidate systems, in terms of their assigned mission priority, with respect to the SoS mission priority, as well as their contribution to the SoS mission.

A Conceptual Methodology for Selecting the Preferred System of Systems

Enhanced 911 is a first line of assistance for practically every emergency situation, and many cell phone users today expect the same results from an emergency call no matter where they are-whether on the side of the road, in the woods, or in a building. It is a vital part of our nation's emergency response and disaster preparedness system. In the context of 911 service, demand for providing reliable and accurate mobile station (MS) location estimation has become a high priority and has gained momentum in recent years. A major challenge in mobile station location estimation is locating an emergency caller within desired accuracy in an adverse environment where non-line-of-site (NLOS) propagation exists. This paper develops a methodology to improve the accuracy of mobile station location estimation in an NLOS environment. A unique feature of this methodology development, compared to other approaches in the literature, is the application of the systems engineering process. While there are many definitions, systems engineering as applied here is an approach and process for developing the preferred solution to a set of requirements. The methodology consists of two stages. In the first stage, a series of time-of-arrival range measurements are made from each base station (BS) to the MS. Binary hypothesis testing on the standard deviation of the range measurements at a given BS is used to determine if the measures are taken under NLOS conditions. Then, if possible, any BS deemed to be NLOS is eliminated from the estimation in the second stage, in which the selected time measurements of several BSs are combined through least squares to estimate the location of the mobile station. Based on a simulation study, the methodology appears to have the potential to significantly improve the accuracy of location estimates in certain situations.

A Systems Engineering Approach to Improving the Accuracy of Mobile Station Location Estimation

Technical Performance Measures TPMs historically are used to help the Program Manager in predicting if a program is on a path to achieve required performance. When extended over a developmental timeline, TPMs have provided a deterministic approach for predicting expected operational performance. However, TPMs are difficult to derive for a complex acknowledged system of systems SoS. An SoS Performance Measure SPM has been developed that is equivalent in purpose to TPMs and demonstrated for a deterministic state similar to TPM usage. However, reality indicates that many of the SoS component variables have significant uncertainty associated with them during the SoS development. Therefore, to more accurately account for the ability of an SoS to achieve its desired performance, this variability needs to be accounted for. This paper extends the deterministic SPM concept to a stochastic SPM to account for this uncertainty. An Antisubmarine Warfare ASW mission example is used, and demonstrates how this extension improves the effectiveness of the SPM methodology.

Incorporating a Measure of Uncertainty into Systems of Systems Development Performance Measures

The target audiences for this paper are systems engineers and architects involved in the design of complex systems such as program organizations. This is the first in a series exploring how the design of program organizations developed for the purpose of designing and developing aerospace and defense systems can be optimized. The objective of this paper is to lay the groundwork for an architecture framework for the development of a program organization. The draft standard ISO/IEC 42010 is used to define the structural requirements of the architecture framework. In addition, we use the Zachman Architecture FrameworkTM to organize the framework and the Department of Defense Architecture Framework Version 2.0 DoDAF 2.0 to create the model environment for the Program Organizational Architecture Framework POAF. This approach to defining the POAF ensured that we would have the data needed to support our objective to optimize the design of the program organization and hopefully reduce the number of defects inherent in the design. We also believe that we have sufficiently defined the characteristics of a POAF to spur more research in this area. © 2012 Wiley Periodicals, Inc. Syst Eng

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/sys.21218

Jerrell T. Stracener

Papers

Systems requirements engineering—State of the methodology

A Conceptual Methodology for Selecting the Preferred System of Systems

A Systems Engineering Approach to Improving the Accuracy of Mobile Station Location Estimation

Incorporating a Measure of Uncertainty into Systems of Systems Development Performance Measures

First steps in the development of a Program Organizational Architectural Framework POAF