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Purpose – This purpose of this paper is to investigate the location problem of supermarkets, feeding by material the mixed model assembly lines using tow trains. It determines the number and the locations of these supermarkets to minimize transportation and inventory fixed costs of the system. Design/methodology/approach – This is done using integer programming model and real genetic algorithm (RGA) in which custom chromosomes representation, two custom mating and two custom mutation operators were proposed. Findings – The performance of RGA is very good since it gives results that are very close or identical to the optimal ones in reasonable CPU time. Research limitations/implications – The study is applicable only if a group of supermarkets feed the same assembly line. Originality/value – For the first time in supermarket location problem, limitation on availability of some areas for possible supermarkets ' locations and capacity of the supermarkets were taken into consideration.

Shipment consolidation is one of main initiatives to reduce CO2 emissions and transportation cost. It reduces the number of shipments per customer and reduces transportation costs by using larger shipments. This paper investigates the temporal consolidation process in a central consolidation center in a make-to-order supply chain. This research was motivated by a case study of a design furniture company that has many suppliers and customers in large parts of Europe. Simulation was used to check the effect of a new and a special time-based temporal consolidation on the response time in outbound logistics. A soft delivery deadline that is less than the average lead time was used because of the long lead time. Arena Software was used to model the supply chain in order to find the best circumstances to use consolidation. Results showed that temporal consolidation could be more effective when order preparation time is with larger variability. The useful waiting is more when there is at least one order every four days. A formula that approximates the percent of reduced shipments was found. Furthermore, many shipments can be reduced without severely affecting the average response time. The value of the study is that it investigates consolidation problems in a high-mix low-volume environment that was overlooked by previous research.

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In this study, material flow from decentralized supermarkets to stations in mixed model assembly lines using tow (tugger) trains is investigated. Train routing, scheduling, and loading problems are investigated in parallel to minimize the number of trains, variability in loading and in routes lengths, and line-side inventory holding costs. The general framework for solving these problems in parallel contains analytical equations, Dynamic Programming (DP), and Mixed Integer Programming (MIP). Matlab in conjunction with LP-solve software was used to formulate the problem. An example was presented to explain the idea. Results which were obtained in very short CPU time showed the effect of using time buffer among routes on the feasible space and on the optimal solution. Results also showed the effect of the objective, concerning reducing the variability in loading, on the results of routing, scheduling, and loading. Moreover, results showed the importance of considering the maximum line-side inventory beside the capacity of the train in the same time in finding the optimal solution.

The current wave of COVID-19 outbreak has created new strategical challenges for policy officials of the industrial sector across the world. The effect of COVID-19 is more in developing economies where industrial sector is already struggling for its stability. This study introduces the impact of COVID-19 on the corporate investment behavior of non-financial publicly listed firms of Pakistan. To achieve the objective, we employ the panel data ranging from 2010 to 2020 and apply the difference-in-differences (DID) model to quantifies the empirical relationship. The outcomes of DID model suggest that the pandemic period and treatment have a significant and negative impact on corporate capital investment behavior. During pandemic spread period, the enterprises have limited their investment into fixed assets due to less productive use of such assets. Similarly, industries that exist in high-impact areas face a negative investment growth rate due to quarantine policy, fewer social movements, and high installing cost of new machinery. However, this negative effect diminishes across those firms that have a quick cash inflow rate and more availability of bank loans. These two factors serve as a financial setback against the adversities of pandemic. By drawing upon the empirical reasoning on the effect of COVID-19, this study also presents possible solutions to alienate unfavorable impacts of this pandemic. Current analysis can be considered as an early attempt towards investigating the consequences of COVID-19 on investment decisions of industrial sector.JEL Classification: G32: G31: G40: C33 Doi: 10.28991/esj-2021-SPER-11 Full Text: PDF

This paper proposes an adaptive transmission modulation (ATM) techniquefor free-space optical (FSO) links over gamma-gamma turbulence channels.The ATM technique provides efficient utilization of the FSO channel capacity for improving spectral efficiency, by adapting the order of the phase-shift keying modulation scheme, according to the channel conditions and the required bit error rate (BER). To overcome the channel degradation resulting from the turbulence effects as well as the pointing errors (PEs), single-input multiple-output (SIMO) system with maximal ratio combining (MRC) is proposed. Exact closed-form expressions of BER and upper bound of the capacity are derived and verified by Monte Carlo simulations. The numerical results show that the proposed adaptive technique improves the spectral efficiency (SE) five times higher than the nonadaptive technique at the same BER threshold (10 −3 ).This improvement is achieved at signal-to-noise ratio (SNR) equals 27 and 42 dB in the case of atmospheric turbulence without and with PE, respectively. Furthermore, this SE could be obtained while the SNR = 30 dB by using (1 × 4) SIMO scheme with MRC and PE and having the same transmitting optical power.