Mansour Rahimi

Jointly optimizing cost, service, and environmental performance in demand-responsive transit scheduling

Abstract In certain fleet systems, the environmental impacts of operation are, to some extent, a controllable function of vehicle routing and scheduling decisions. However, little prior work has considered environmental impacts in fleet vehicle routing and scheduling optimization, in particular, where the impacts were assessed systematically utilizing life-cycle impact assessment methodologies such as those described by the Society of Environmental Chemistry and Toxicology. Here a methodology is presented for the joint optimization of cost, service, and life-cycle environmental consequences in vehicle routing and scheduling, which we develop for a demand-responsive (paratransit or dial-a-ride) transit system. We demonstrate through simulation that, as a result of our methodology, it is possible to reduce environmental impacts substantially, while increasing operating costs and service delays only slightly.

Merging strategic safety, health and environment into total quality management

Abstract The philosophy of Total Quality Management (TQM) appears to be a major force in the reshaping of the U.S. industry. Increasingly, internal customers (e.g. workers) require work environments that are safe, healthy and environmentally benign. On the other hand, external customers require products and services that are safe and present no negative environmental consequences. Thus, it is suggested to integrate long-range safety planning into the current TQM efforts. First, the concept of Strategic Safety Management (SSM) is proposed to merge these two approaches. Then, the main features of SSM are presented. Self-managed team work is described as an essential linking component of this integration to promote long-term safety and quality improvements. Certain aspects of an organizations performance measurement and reward (merit) system are also highlighted within the SSM framework. Due to its “total” systems approach and its long-range planning and implementation requirements, there are many obstacles to its full effective operation. Many of these problems are briefly mentioned. Finally, potential for its success in smaller organizations is presented.

Effects of computerized automation and robotics on safety performance of a manufacturing plant

Abstract Karwowski, W., Rahimi, M. and Mihaly, T., 1988. Effects of computerized automation and robotics on safety performance of a manufacturing plant. Journal of Occupational Accidents, 10: 217–233. Safety performance of a Kentucky-based appliance manufacturer was compared before and after computer automation of the assembly process. Specifically, incidence rates were calculated for one-year pre- and post-automation periods for each of the following ANSI classifications: nature of injury, part of body, source of injury, accident type, hazardous condition, and unsafe act. After automation, incidence rates increased for employees working on the main assembly line. Operators of automated equipment had the greatest percentage of dispensary visits, possibly as a result of their efforts to meet production requirements. The post-automation plant environment created new hazards to maintenance personnel. However, the plant modifications improved the material handling procedures: the number of employees exposed to debris was reduced and fewer accidents related to materials handling occurred. This study points out that timely and accurate analysis of workplace accidents and injuries is essential for identifying and preventing industrial accidents. Furthermore, the present investigation reinforces the need for an efficient and thorough record-keeping system that includes categories for non-traditional equipment such as robots.

Systems safety for robots: An energy barrier analysis

Abstract Rahimi, M., 1986. Systems safety for robots: An energy barrier analysis. Journal of Occupational Accidents , 8: 127–138. The need for a comprehensive study of hazards caused by robot work environments is stressed. Based on previous data and robot accident reports, major factors contributing to robot accidents are classified and listed. System safety is introduced as an appropriate approach to analyze safety of semiautomated and automated robot systems. A general procedure for conducting system safety analysis is presented. Energy Barrier Analysis (EBA), a qualitative system safety technique, is applied to a general model of human—robot system. Major concepts of EBA are integrated in a stepwise approach for evaluating and designing robot safety systems. As the result of this application, specific solutions and recommendations are discussed.

A research paradigm in human-robot interaction

Abstract This paper reviews critical issues in human-robot interaction area, and proposes a research framework to study human aspects of robotic system design. The main emphasis is on system design whereby machine and human related variables interact in the context of task performance. A macro-systems approach is suggested to indicate different categories of behavior related to human and robot components. The current directions and future of research on human activities in relation to robotic systems are discussed.

Human perception of robot safe speed and idle time

Abstract Operators and users of robotic systems perform tasks which require close proximity to dangerous moving parts. Two experiments were performed to assess human perception of safe robot arm speed and idling times. Experiment 1 was designed to determine the maximum safe speed of robots. Subjects were asked to adjust the robot speeds. Perceived safe speeds were indicated for two different types of robots. Experiment 2 was designed to determine safe programmed idle time of robots. Subjects were asked to enter the robot work envelope when a programmed idle was perceived to be caused by a malfunction. Safe idle times were reported for two different robot speeds during operational cycles.

Sustainable Reverse Logistics for Distribution of Industrial Waste/Byproducts: A Joint Optimization of Operation and Environmental Costs

Byproducts and waste materials are potentially valuable inputs into a variety of industrial processes. Markets are being developed to capitalize on the use and reuse of these materials as inputs. The literature on reverse logistics analysis mostly concentrates on the end-of-life product recovery systems and mainly does not address the recovery process for waste/byproduct streams in an exchange network among industries. We have developed a reverse logistic model that minimizes the operational and environmental costs of exchanging waste and byproduct materials in a business-to-business network. The network contains firms, value-added process (VAP) centers (e.g., disassembly, recycling, or remanufacturing), disposal centers, and a virgin material market. The model takes the form of a mixed integer linear model. The model output contains the locations of the VAP centers and the material movement that minimizes the weighted sum of the operational and environmental costs. Because the problem is NP-hard, we developed a genetic algorithm (GA) to efficiently solve the model for large-sized problem instances. We demonstrated the modeling and solution approach for aluminum waste/byproducts in Los Angeles County. For this demonstration, we used data results from numerous past studies to assess the operational costs of waste/byproduct collection, processing, and movement. To estimate the environmental costs and parameters, we utilized published economic input-output results from previous studies. This model can be used as a guide for policies to encourage the development of sustainable supply networks.

Decision Analysis Utilizing Data from Multiple Life-Cycle Impact Assessment Methods Part I: A Theoretical Basis

Numerous methodologies for the life-cycle impact assessment (LCIA) step of life-cycle assessment (LCA) are currently in popular use. These methods, which are based on a single method or level of analysis, are limited to the environmental fates, impact categories, damage functions, and stressors included in the method or model. Because of this, it has been suggested within the LCA community that LCIA data from multiple methods and/or levels of analysis, that is, end-point and midpoint indicators, be used in LCA-based decision analysis to facilitate better or, at least more informed, decision making. In this (two-part) series of articles, we develop and present a series of LCA-based decision analysis models, based on multiattribute value theory (MAVT), which utilize data from multiple LCIA methods and/or levels of analysis. The key to accomplishing this is the recognition of what LCIA damage indicators represent with respect to decision analysis, namely, decision attributes and, in most cases, proxy attributes. The use of proxy attributes in a decision model, however, poses certain challenges, such as the assessment of decision-maker preferences for actual consequences that are only known imprecisely because of inherent limits of both LCA and scientific knowledge. In this article (part I), we provide a brief overview of MAVT and examine some of the decision-theoretic issues and implications of current LCIA methods. We illustrate the application of MAVT to develop a decision model utilizing damage indicators from a single LCIA methodology; and, we identify the decision-theoretic issues that arise when attempting to combine LCIA indicators from multiple methods and/or levels of analysis in a single decision model. Finally, we introduce the use in our methodology of constructed attributes to combine related end-point damage indicators into single decision attributes and the concept and evaluation of proxy attributes.

Human Perception of the Maximum Safe Speed of Robot Motions

A laboratory experiment was conducted to determine the maximum speeds of robot arm motion considered by the subjects as safe for human operators working in a close proximity of the robots working envelope. Twenty-nine college students (16 males and 13 females) participated in the study as monitors of the simulated assembly tasks performed by two industrial robots of different size and work capabilities. The results show that the speed selection process depends on the robots physical size and its initial speed at the start of the adjustment process. Subjects selected higher speeds as “safe” if they were first exposed to the maximum speed of the robot, and significantly lower values when the initial speed of the robots actions was only 5% of maximum. It was also shown that the subjects previous exposure to robots and the level of their knowledge of industrial robots highly affected their perception of safe speeds of robot motions. Such effects differ, however, between males and females.

Life-Cycle Emissions from Port Electrification: A Case Study of Cargo Handling Tractors at the Port of Los Angeles

ABSTRACT To reduce greenhouse gas emissions, ports around the world are considering using electric cargo handling equipment. To assess the benefits of the strategy, this study provides a comparative life-cycle assessment between diesel and electric yard tractors in a case study of the Port of Los Angeles. Results indicate a significant reduction in life-cycle emissions as the port shifts to electric vehicles and as the ports electricity supplier increases its use of renewable energy sources (e.g., wind and solar). The results also demonstrate that even with aggressive electrification strategies, the ports legislated reduction targets are not achievable by the year 2030.