Analytical approaches to planning intermodal transportation systems for regular and hazmat freight

The world container transportation industry has grown significantly over the past few decades. Large numbers of containers are transported everyday over long distances via a single or combinations of different modes of transportation (road, rail, water and air). Many of these containers contain hazardous materials (hazmat) whose transportation is regulated by governments due to the related risks. In contrast to other areas of transportation, operations-research-based models for intermodal transportation of containers, specifically hazmat ones, is still a young domain. The purpose of the thesis is to provide analytical approaches to planning intermodal transportation for regular and hazmat freights. Planning of intermodal transportation can be addressed at the strategic, tactical or operational level. In this regard, this thesis contributes to the current literature in the following three ways. First, at the operational level, we study crane scheduling at an intermodal terminal, such that the unloading of inbound vessels and the loading of outbound vehicles could be completed in minimum weighted time. The approach calls for a multi-processor multi-stage scheduling methodology, where each crane has availability time windows. Second, at the tactical level, we propose a routing framework for transportation of hazmat and regular containers in a congested network to minimize two objectives: total cost and total risk. The model considers congestion as a source of exposure and makes a trade-off between congestion exposures and capacity costs. Third, at the strategic level, we study the regulation of intermodal transportation for hazardous materials. A bi-level network design model and a bi-level bi-objective toll-setting policy model, which consider government and carrier at two levels of administration, are proposed to mitigate the transportation risk. The thesis concludes with comprehensive remarks. We summarize the contributions of this thesis, show the overall results obtained, and present the possible directions that this research may take in the future

THE DISCRETE TIME, COST AND QUALITY TRADE-OFF PROBLEM IN PROJECT SCHEDULING: AN EFFICIENT SOLUTION METHOD BASED ON CELLDE ALGORITHM

<p>ENGLISH ABSTRACT:The trade-off between time, cost, and quality is one of the important problems of project management. This problem assumes that all project activities can be executed in different modes of cost, time, and quality. Thus a manager should select each activity’s mode such that the project can meet the deadline with the minimum possible cost and the maximum achievable quality. As the problem is NP-hard and the objectives are in conflict with each other, a multi-objective meta-heuristic called CellDE, which is a hybrid cellular genetic algorithm, is implemented as the optimisation method. The proposed algorithm provides project managers with a set of non-dominated or Pareto-optimal solutions, and enables them to choose the best one according to their preferences. A set of problems of different sizes is generated and solved using the proposed algorithm. Three metrics are employed for evaluating the performance of the algorithm, appraising the diversity and convergence of the achieved Pareto fronts. Finally a comparison is made between CellDE and another meta-heuristic available in the literature. The results show the superiority of CellDE.</p><p>AFRIKAANSE OPSOMMING: ‘n Balans tussen tyd, koste en gehalte is een van die belangrike probleme van projekbestuur. Die vraagstuk maak gewoonlik die aanname dat alle projekaktiwiteite uitgevoer kan word op uiteenlopende wyses wat verband hou met koste, tyd en gehalte. ‘n Projekbestuurder selekteer gewoonlik die uitvoeringsmetodes sodanig per aktiwiteit dat gehoor gegegee word aan minimum koste en maksimum gehalte teen die voorwaarde van voltooiingsdatum wat bereik moet word.<br /><br /> Aangesien die beskrewe problem NP-hard is, word dit behandel ten opsigte van konflikterende doelwitte met ‘n multidoelwit metaheuristiese metode (CellDE). Die metode is ‘n hibride-sellulêre genetiese algoritme. Die algoritme lewer aan die besluitvormer ‘n versameling van ongedomineerde of Pareto-optimale oplossings vir voorkeurgedrewe besluitvorming. Uiteenlopende probleme word opgelos deur die algoritme. Drie verskillende waardebepalings word toegepas op die gedrag van die algoritme. Die resultate bevestig die voortreflikheid van CellDE.</p&gt

Bioassay Screening of the Essential Oil and Various Extracts of Nigella sativa L. Seeds Using Brine Shrimp Toxicity Assay

Background and Aim: Since cytotoxicity screening is the first step necessary for any new drug development, this study was designed to find out and compare the cytotoxicity effects of the essential oil and various extracts of Nigella sativa L. seeds using Brine Shrimp Lethality (BSL) assay. Materials and Methods: Essential oils and various extracts of N. sativa were assessed by two methods of disk and solution of BSL. Data analysis was carried out using SPSS statistical package version 17.0 (SPSS Inc., Chicago, IL, 250 USA). Data were processed in probit-analysis program to estimate LC50 values. Results: All of the tested fractions demonstrated more cytotoxicity in the solution method. Petroleum ether and chloroform extract of N. sativa showed the most cytotoxicity with LC50 values 7 and 21 μg/ml respectively; while aqueous and ethanolic had no significant cytotoxicity. Moreover, the GC/MS analysis of the essential oil of N. sativa showed the p-cymene (48.1%), α-thujone (14.38%) and dihydro carveol (9.11%) as the main compounds. Conclusion: These results suggest some limitation for using this spice in diet. Furthermore, this plant could be considered as a source of cytotoxic compounds which should be studied in details