Showing papers by "Babak Abbasi published in 2019"

Proactive transshipment in the blood supply chain: A stochastic programming approach

Abstract: The main objective when managing inventories in blood supply chains is to establish an efficient balance between the wastage and shortage of blood units. The uncertain demand and the perishable nature of blood units can result in over- or under-stocking and increase wastage and shortage costs. In this study, we analyze how a proactive transshipment policy can avoid future shortages in addition to mitigate wastage. We consider a network of hospitals with uncertain demand in which each hospital makes decisions on the quantity to order from a central blood bank and to transship to other hospitals in each review period. We formulate the problem as a two-stage stochastic programming model. To generate scenarios, the Quasi-Monte Carlo sampling approach is employed and the optimal number of scenarios is determined by conducting stability tests. We performed numerical experiments to evaluate the performance of the proposed model and investigate the potential benefits of the outlined proactive transshipment. The developed model is used to compare the optimized policy with the current practice in some hospitals in Australia and with a no-transshipment policy. The numerical results indicate significant potential cost savings in comparison with the current policy in use and the no-transshipment policy.

Optimal Work Assignment to Multiskilled Resources in Prefabricated Construction

Abstract: Multiskilling allows for dynamic reallocation of workers from one stage of production to another in response to bottleneck configurations and, therefore, has been advocated as a potential s...

Skill set configuration in prefabricated construction: hybrid optimization and multicriteria decision-making approach

Abstract: In offsite construction, unbalanced distribution of resources can cause heterogeneity in the production environment and result in cost and time overruns. It is of particular importance to e...

Critical Literature Review of Labor Multiskilling in Construction

Abstract: Research in multiskilling experiences an incremental trend from academic, industrial, and governmental point of views. Different methodologies have been used in previous research to identif...

Airline capacity decisions under supply-demand equilibrium of Australia's domestic aviation market

Abstract: Australia is especially reliant on air transportation because of the geographical distribution of the urban centers across the country. This paper seeks to identify the antecedents of the capacity decisions of the airlines operating in Australian domestic aviation market. We examine the factors on both sides of the supply-demand equilibrium using monthly data of twenty-one major domestic routes linking eight major cities between January 2004 and December 2015. To investigate the relationship between flight demand and the variables of capacity decisions (flight frequency, aircraft size, load factor, and available seats), the pooled series cross-sectional data are analyzed using a two-stage least-squares method to model the supply-demand interaction. The results statistically differentiate the airlines’ strategies regarding capacity decisions for the short-haul, medium-haul, and long-haul routes. The results suggest that competition would lead to more flights, smaller aircraft size, lower load factors, and more available seats in all markets. Low-cost carriers play a key role in the short-haul market. Higher jet fuel prices scales up aircraft size on all flight routes. Notably, the socio-economic parameters of population and employment rates affect flight demand more strongly on the long-haul routes than other routes.

Antecedents of flight delays in the Australian domestic aviation market

Abstract: Flight delays are widespread and growing around the world. Using public domain data of the airlines in Australia's domestic aviation market, this study investigates the antecedents of flight delays, and how airline operations contribute to such an important issue in the aviation industry. Applying the Hausman-Taylor regression method, the estimations suggest that the variables of the airline capacity decision are meaningful determinants of flight delays. Our findings inform that more frequent flights and larger aircraft are associated with more flight delays. A higher level of route congestion leads to more flight delays, especially for the low-cost carriers. Jet fuel price is identified as a driver, leading to more flight delays for the legacy airlines compared to the low-cost carriers. Keen competition between the airlines actually helps to improve the flight service quality, through fewer flight delays.