Esra Aleisa

For effective facilities planning: layout optimization then simulation, or vice versa?

It is widely accepted that simulation is an integral part of any effective facilities planning or layout study. Traditional approaches claim that layout optimization produces strategic results and therefore should precede simulation analysis, which focuses on operational issues. On the other hand, more recent studies suggest that running simulation models prior to conducting layout optimization produces more realistic layouts. In this paper, we contrast these two paradigms, with respect to the general assumptions and the types of applications that advocates from each paradigm have used to support their claim. In addition, we propose guidelines on which approach to pursue according to the layout study objectives and the characteristics of the system under consideration.

A baseline study characterizing the municipal solid waste in the State of Kuwait.

This paper provides a new reference line for municipal solid waste characterization in Kuwait. The baseline data were collected in accordance with the Standard Test Method for the Determination of the Composition of Unprocessed Municipal Solid Waste (ASTM). The results indicated that the average daily municipal waste generation level is 1.01 kg/person. Detailed waste stream surveys were conducted for more than 600 samples of municipal solid waste (MSW). The waste categories included paper, corrugated fibers, PET bottles, film, organic matter, wood, metal, glass, and others. The results indicated that organic waste dominated the characterization (44.4%), followed by film (11.2%) and then corrugated fibers (8.6%). Analysis of variance (ANOVA) was used to investigate the influence of season and governorate on waste composition. A significant seasonal variation was observed in almost all waste categories. In addition, significant differences in proportions between the current level and 1995 baseline were observed in most waste categories at the 95% confidence level.

Team Formation in Concurrent Engineering Using Group Technology (GT) Concepts

Concurrent engineering (CE) has emerged as an essential design principle that facilitates rapid and efficient product development that is necessary to survive in today’s fiercely competitive environment. However, the lack of tools that address design team formulation and proper design task assignment in CE has made its application an immense challenge. In this article we explicitly address this issue by pointing out the relevance of its structure to cell-formation problem in cellular manufacturing (CM) and group technology. Particularly, interdisciplinary CE teams will be formulated as multifunctional machine-cells that process similar parts, in our case, design tasks requiring involvement of similar individuals. The fruitful marriage of the two disciplines, concurrent engineering and cellular manufacturing, opens the path towards utilizing the ample existing efficient algorithms of cellular manufacturing to concurrent engineering rather than re-inventing the wheel in developing methods in this respect. The paper in-hand also incorporate sequences (or routing in cellular manufacturing) to create work teams that can conduct similar tasks commonly known as work packages in a smoother manner that avoids unnecessary back and forth alterations and overlapping. In addition, to enable solving the task assignment problem in reasonable time for relatively larger problems, the developed framework integrates a fuzzy ART algorithm proven efficient in cellular manufacturing literature. The article also provides an illustrative example on executing the methodology on a design example and highlights its implications on task team assignments.

Sequencing of design tasks based on the degree of permissible concurrency

Rapid product design and development are crucial factors to maintaining a competitive advantage in todays intense market. Time-consuming iterative design cycles cause critical delays within the design development process. One widely applied method to identify such iterations is the design structure matrix (DSM). Due to its distinctive ability in consistently rearranging factors of a complex problem using subjective measures, the analytic hierarchy process (AHP) was requisitely applied to quantify DSM binary relations. Despite its advantages, AHP becomes intractable for large design problems, where substantial pairwise comparisons take place. The core contribution of this paper is overcome this drawback, thus facilitate faster sequencing of design tasks within a quantified DSM while utilising the benefits of AHP. This will lead to reducing time spent in iterating within design subcycles and eventually reduce time-to-market. The developed methodology is illustrated on a design of a low emission vehicle (LEV).

Design and management of a sewage pit through discrete-event simulation

This paper reports two discrete-event simulation studies to model the activities of a residential waste treatment facility and prepare it to accept additional wastewaters through tanker trucks. The first simulation study models the wastewater treatment facility to ensure its ability to handle the planned added capacity arriving through the pit, while the second study simulates various managerial strategies to handle the traffic, testing, and unload procedures of tanker trucks arriving at the facility. The simulation models were statistically validated and the outcomes of the study were implemented in reality. The wastewater treatment facility extension suggested by this study was implemented and launched in mid 2008 to accept residential wastewater tanker trucks. This has saved the environment over 6,000 m3 daily from being dumped into the open unlined terrestrial landfills. Simulation proved to be an excellent tool in the facility planning effort, as it ensured smooth flow lines of tanker truck load discharge and the best utilization of facilities on site.

Application of discrete event simulation to design and management of waste water pit — A case study

This paper comprises a study to escort the design and management of a residential sewage holding pit near a local water treatment facility. The pit is designed to replace an existing waste dump area. The study consists of a discrete-event simulation for predicting performance, capacity, utilization and flow at pit and its support activities. The pit is designed receive residential sewage tank truck loads, hold it temporally, and then pipe daily accumulated loads to the nearby water treatment facility. Simulation turned out to be an excellent tool in the facility planning effort for the pit project, as it insured smooth flow lines of tank trucks load discharge and best utilization of facilities on site.

Wastewater reuse in the countries of the Gulf Cooperation Council (GCC): the lost opportunity

Reuse of treated wastewater is not only environmentally and financially sound, it is becoming indispensable for meeting the staggering water demand in certain regions, especially under conditions of alarming water scarcity. Reusing treated wastewater will help in reducing the pressure on expensive desalinated water production and depleting groundwater withdrawal, thereby reducing associated harmful environmental impacts. Reuse of wastewater in general and in the countries of the Gulf Cooperation Council (GCC) in particular has been a priority research area and has been in the media spotlight for some time, especially the use of tertiary quality water resources for agricultural purposes. However, reuse of treated wastewater is still in its primitive stage in terms of implementation in GCC. In addition, the overall volume of tertiary treated water that outflows unutilized to the sea is much greater than the volume reused. This paper provides a general review of and statistics on current practices of treatment of domestic wastewater in the GCC. The review highlights water resources, sanitation service coverage, wastewater treatment, effluent types, treated and reuse quantities, costs, and tariffs. The paper provides recommendations to improve wastewater treatment in the GCC to alleviate the stress on the scarce groundwater resources, provide a relatively inexpensive alternative to desalination, reduce the environmentally adverse impacts and externalities of desalination plants, and eliminate the discharge of untreated wastewater in coastal areas or terrestrial landfills.

A triple bottom line evaluation of solid waste management strategies: a case study for an arid Gulf State, Kuwait

PurposeWe extend a life cycle assessment (LCA) embracing both economic and social perspectives to develop an integrated solid waste management system for Kuwait. This study considers the domestic waste generated by households and waste generated commercially. Six municipal solid waste (MSW) scenarios (SR1, SR2, …, SR6) are evaluated using a triple bottom line (TBL) approach that incorporates environmental, financial, and social bottom lines (social BLs).MethodsWithin the TBL framework, the environmental BL employs LCA in accordance with ISO 14044. The financial BL is calculated using capital and operational costs as well as the associated recycling revenues. The social BL applies macro-economic indicators that examine the effects of a given MSW scenario (SR) on the inhabitants. To integrate the TBLs, we apply an analytic hierarchy process (AHP) because of its advantage of pairwise unit-free rescaling. The relative importance of each BL is determined by considering the political, legal, socio-cultural, and economic climates of the country. The relative weights are cross-multiplied with indicators from each BL to calculate a composite sustainability index (CSI) for the proposed MSW SR.Results and discussionThe environmental BL (LCA) indicates that global warming, acidification, and human toxicity are the most adversely affected impact categories, considering the local conditions and waste composition. Environmentally, SR1 (landfilling) scored the worst in almost all impact categories and, thus, was labeled the worst-case scenario environmentally. SR6 (composting, recycling, and incineration) performed the best from an environmental perspective. Financially, landfilling (SR1) is the most economical scenario. Any SR that focused on incineration (SR2 and SR5) was financially unfavorable. The scenarios that involved composting were scored as financially reasonable (SR3, SR4, and SR6). From a social acceptability perspective, SR2 (incineration) scored the highest, while SR1 (landfills) scored the lowest. Finally, across the TBL framework, SR4 (composting and incineration) had the highest CSI based on the relative importance scheme adopted for each BL.ConclusionsAlthough they are often overlooked in most LCA studies, the financial and social aspects are indispensable to proving feasibility and credibility at a strategic level. The complexity of financial and social formulations in LCA is inherited from the difficulty in quantifying emissions and other impacts. In addition, from a social perspective, the contingent risks and associated uncertainty vary widely across cultures, ideologies, and degrees of development and are further complicated because of the scarcity and uncertainty of the data.

Modeling of Firefighting Operations through Discrete Event Simulation

This paper reports the results of applying discrete event simulation on firefighting operations in the State of Kuwait. The objective was reduce response times to reach fires in all districts to below five minutes. The Simulation of output runs were analyzed using ANOVA. The results were validated at 95% confidence level. Simulation turned to be an excellent tool for testing a major change without disturbing firefighting operations. 

Using discrete-event simulation to evaluate a new master plan for a sanitary infrastructure

Increasing population and changes in life style have caused the wastewater network to deteriorate while exceeding their designed capacities. The Ministry of Public Works (MPW) is planning on expanding the capacities of some treatment plants and demolishing and replacing others with new ones by 2045. To asses this expansion, the current wastewater network was analyzed and the amount of untreated sewage water that is dumped into the sea was taken into consideration. The current network is composed of twelve main pumping stations and four treatment plants. Using discrete-event simulation, the current and future situations were modeled and the outputs were compared. This gives us a valid base to give recommendations for this large infrastructure project.