mohsen sheikh sajadieh
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Journal of Advances in Industrial Engineering, Volume:58 Issue: 1, Winter and Spring 2024, PP 219 -236Efficient flow management is critical in transportation and logistics, with hub networks playing a key role in optimizing these processes. The hub arc location problem has recently emerged as a new framework that emphasizes hub arcs while allowing for isolated hubs. This paper extends the hub arc location problem by incorporating set-up costs into the optimization model. A heuristic algorithm is developed to enhance hub network design, considering both the flow of goods and the associated hub set-up costs. Additionally, a detailed sensitivity analysis is conducted to assess the impact of strategic adjustments on optimization outcomes. By reducing the discount factor for inter-hub flows and increasing the number of exogenous hub arcs, significant improvements in route optimization and cost reduction are achieved. This research challenges traditional approaches to hub network design and opens the door for further exploration of the dynamics within hub networks. A deeper understanding of these networks can lead to more efficient and resource-optimized transportation systems, potentially transforming flow management into a more cost-effective and sustainable process.Keywords: Hub Arc Location, Hub Network, Greedy Heuristic Algorithm, Isolated Hub
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Journal of Optimization in Industrial Engineering, Volume:17 Issue: 36, Winter and Spring 2024, PP 35 -54
Hub networks play a crucial role in optimizing transportation flow and reducing overall costs by efficiently connecting origins and destinations through strategically placed hub nodes. The decision of hub location carries significant long-term implications and necessitates consideration of various factors within an uncertain environment. This paper addresses the hub arc location problem in hub networks, considering setup costs, isolated hubs, and uncertain flows between nodes. To tackle this challenge, a two-stage stochastic programming model is formulated to incorporate the uncertainty in flow volumes. Additionally, a robust optimization approach is proposed to enhance the resilience of hub location decisions against uncertain scenarios. The problem is solved using a tailored Genetic algorithm, which achieves optimal solutions with high quality and reasonable computational time. The results demonstrate the effectiveness of the proposed methodology in handling the uncertain nature of the hub location problem, contributing to the advancement of transportation planning and logistics optimization. The findings provide valuable insights for practical applications in real-world scenarios, offering a framework for decision-makers to make informed choices regarding hub network design and location. By integrating uncertainty and robust optimization techniques, this paper offers a comprehensive approach to address complex transportation network problems and improve overall efficiency in transportation systems.
Keywords: Hub Arc Location, Isolated Hub, Uncertainty, Robust Optimization, Min-Max Regret Model, Genetic Algorithm -
This paper studies a name-your-own-price (NYOP) mechanism in which the retailer allows buyers to participate in the pricing process by submitting bids. Buyers can place both joint and individual bids to purchase products either as a bundle or individually. The retailer utilizes NYOP and posted-price channels simultaneously. The focus of this paper is to assess the impact of adding the postedprice channel and bundling option on buyer behavior and retailer profit. The paper develops a two-stage model where the first stage involves the buyer’s decision on participating in NYOP. Moreover, buyers can choose between bidding for a bundle or a single item. Decisions in the second stage depend on the outcome of the first stage. Four distinct purchasing scenarios are formulated to outline the potential ways that buyers can use to purchase products. Furthermore, the buyers’ learning effect on their bidding strategy is considered. A dynamic programming approach with backward induction is employed to solve the problem. Moreover, the concavity analysis is used to obtain the solution of each nonlinear subproblem. Then, a solution algorithm based on mathematical analysis is proposed. Results reveal that the frictional costs of the first period have a greater impact on the buyer utility than those of the second period. Moreover, applying the NYOP alongside the posted-price can enhance the retailer’s profit. In particular, the retailer can use the NYOP and bundling mechanisms as encouraging tools to attract buyers and increase his profit. Thus, NYOP is a very effective instrument for market penetration.
Keywords: Participative pricing, Name-your-own-price, Bundling, Dynamicprogramming, Convex optimization, Non-linear programming -
Demand fluctuations, customer’s behavior and price of products can greatly impact on distribution systems. Here, pricing decisions in a distribution system is focused considering customer behavior in a competitive market. A behavior-based bi-level model is proposed to present the Stackelberg competition among the wholesalers and retailers in a distribution system under two distinct scenarios. The defined scenarios attempt to focus on profit and utility maximization for the distribution system and customers, respectively. In addition, behavior-based price discrimination is used in the current paper considering retail prices and customer geographical zones in the market. The developed model is finally carried on an industrial case problem to derive sensitivity analyses and compare different scenarios to get managerial insights.Keywords: Behavior-based price discrimination, game theory, retail systems, Stackelberg competition, Revenue Management
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با توجه به نگرانی جهانی در خصوص محیطزیست، ایجاد زنجیره تامین معکوس به عنوان یک استراتژی مهم در راستای کاهش برداشت از منابع طبیعی شناخته می شود. در این تحقیق یک مدل برنامهریزی عدد صحیح آمیخته خطی برای طراحی شبکه زنجیره تامین معکوس توسعه یافته است. در این مدل لایه های زنجیره به صورت چندگانه تعریف شده است. نیز هدف این مدل بیشینه سازی درآمد ناشی از فروش محصولات بازیابی شده از فرایندهای استفاده مجدد، بازسازی، بازتولید، بازیافت و فروش قطعات یدکی است. همچنین در نظر گرفتن تنوع محصولات و لیست قطعات هر محصول ازجمله ویژگی های مدل توسعه داده شده است. برای حل این گونه مسایل نیز الگوریتم ترکیبی بر پایه الگوریتم ژنتیک و الگوریتم شاخه و کران توسعه یافته است. اعتبارسنجی این الگوریتم با کمک داده های تصادفی ایجاد شده در ابعاد مختلف، بررسی شده است. همچنین در انتها، تحلیل حساسیت تابع هدف نسبت به تغییرات پارامترهای کلیدی ارزیابی شده است.کلید واژگان: طراحی شبکه زنجیره تامین، لجستیک معکوس، الگوریتم ترکیبی، بازتولید و استفاده مجدد، بازسازی و بازیافتJournal of Industrial Engineering Research in Production Systems, Volume:8 Issue: 16, 2020, PP 185 -197;Due to environmental concerns along the world, reverse logistics now is becoming an important strategy to decrease resource extraction. This research develops a generic mixed integer linear programming model for reverse logistics network design. This is a multi-echelon reverse logistics model. It maximizes total profit by handling products returned for reuse, refurbishing, remanufacturing, recycling and sale of spare parts. Also considering product variety and bill of material are model features. A hybrid algorithm constructed by genetic algorithm and branch and cut algorithm is proposed to solve the constructed problems. The designed model is validated and tested by using data generated in various size. Sensitivity analyses are conducted on various parameters to illustrate the capabilities of the proposed model.Keywords: Reverse supply chain network design, Reverse logistics, Hybrid algorithm, Remanufacturing, reuse, Refurbishing, recycle
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امروزه، تعامل بلندمدت با تامین کنندگان در زنجیره تامین به فعالیت کلیدی سازمان ها تبدیل شده است و شرکت ها می کوشند به کمک آن، قابلیت های خود را بهبود بخشند. بر همین اساس، با توجه به محدودبودن تامین کنندگان توانمند، پیشرفت های مستمر تکنولوژیکی و نیازهای جدید بازار، لازم است لیست کوتاه تامین کنندگان هر سازمان گسترش یابد که فرایندی زمان بر و پرهزینه است؛ بنابراین توسعه قابلیت های رقابتی تامین کنندگان، راهکاری برای ایجاد منافع مشترک برای تمامی اعضا خواهد بود؛ اما جایگاه مناسب ارتقای تامین کنندگان کجاست و مقدمه آن چیست. در این پژوهش، مدلی فرایندی به همراه نرم افزار توسعه تامین کنندگان در حوزه پیمانکاری، با استفاده از الگوهای کیفی و مدل های پشتیبان تصمیم، همسو با پایداری زنجیره تامین معرفی شد. بدین منظور در کنار عوامل رشد، الزام های مشتری و صاحبان منافع در ابعاد زیست محیطی، اجتماعی و اقتصادی گنجانده شد. برای رسیدن به چنین دستاوردهایی، از روش هایی نظیر سرمایه گذاری، ارتقای اهداف کلیدی عملکرد و آموزش بهره گرفته شد. برای ارزیابی مدل پیشنهادی، ده تامین کننده واجد شرایط بهبود شرکت کنگلومرای پیمانکاری در حوزه های مختلف در ایران شناسایی و در هفت ماه در سه بخش شناخت، توسعه و پایش، و اجرا تحلیل شد. با توجه به نتایج، اعتبار مدل و نرم افزار در پنل های خبرگی پایش و تایید شد. از نوآوری های این پژوهش می توان به پیاده سازی هم زمان سه مرحله مدل در قالب مدلی یکپارچه اشاره کرد. محدودیت های این پژوهش، چالش در جلب مشارکت تامین کننده و اجازه ورود کارفرما به جزییات و طولانی شدن اجرای برخی اقدامات بهبود بوده است.
کلید واژگان: توسعه و بهبود تامین کننده، ارزیابی تامین کننده، زنجیره تامین پایدارPurposeLong-term interaction with supplies in supply chains has nowadays become a key activity in organizations, and the companies attempt to improve their capabilities by using it. Due to the limitations of capable suppliers, ongoing technological developments, and the market's new requirements, it is necessary to develop the shortlist of each organization's suppliers, which is both time-consuming and costly. Thus, the development of suppliers' competitive capabilities is a strategy for creating shared benefits for all members. But, what is the correct position of the suppliers' development? What is its preface?This research aims to design a model for the development of the suppliers of a contractual holding company within the domain of engineering and design, production, construction, erection, and commissioning to establish sustainability in the supply chain. Therefore, by creating a model, through giving prominence to appropriate relations with each supplier, the improvement of the suppliers through the combination of qualitative and decision support models will be provided, so that all quantitative and qualitative criteria of purchase management are taken into consideration.
Design/methodology/approachIn this research, a process model and software for suppliers' development in the contraction field is provided employing qualitative patterns and decision support models for the sustainability of the supply chain. For this, along with the growth factors, requirements of customers, and beneficiaries in environmental; social, and economic dimensions are included. Therefore, methods such as investment, performance enhancement of key purposes, and training are used. To evaluate the suggested model, ten suppliers, qualifying the requirements of the conglomerate contractual company, are recognized and analyzed for seven months in cognitive, development-monitoring, and executive sections. The results obtained confirm the validity of the model and software in expert panels.
FindingsThe main findings of this research are the design of a comprehensive process model and software within a sustainable development framework. In the recent model, contrary to the previous research, all different working areas of the suppliers for all contractual companies with the various buyer and seller relations have been considered inclusively. The output of this model is the plan for the integrated development and improvement of each supplier.The tracking of the improvements gained for different areas shows that, out of 39.29 percent total improvement, 15.99 percent is related to 40 percent of the suppliers with strategic unity. The remaining 23.30 percent is related to other suppliers.
Research limitations/implicationsThe challenges are motivating suppliers' participation, the permission of client involvement into details, and delay of some development plans. For further research, it is suggested that the chapters of recognition instruments and the gap analysis be revised and, if necessary, the empty module of the model be completed. For the software section, the system can be developed integrally online.
Practical implicationsThrough reviewing suppliers, the development of suppliers was classified in the form of investment conglomerate company through consultation and training, persuasion, promotion of performance goals, the necessity to execute standards, and supervising their execution and legal obligations and determination of the strategies and key objectives. The other development tool was provided appropriate for any action suggested. The main barriers of improvement actions to be implemented by suppliers can be summarized as the lack of organization’s senior managers’ support due to the informal execution of the project within a short time (seven months), and more than one-year time needed for improvement actions (i.e., the results of the actions were not achieved in monitoring section).
Social implicationsAs the development and implementation of the model are related to the sustainable supply chain, the social responsibility in each supplier is also promoted through the assessment of the indicators. For this purpose, various methods including rules implementations, following national and international standards, training and investment are used.
Originality/valueThe novelty of this research is the development and simultaneous implementation of the three phases (assessment, development, and monitoring) in an integrated sustainable supplier development model.
Keywords: Supplier development, Supplier evaluation, Supply Chain Sustainability -
This paper proposes a truck scheduling model in a cross dock system under multi-period, multi-commodity condition with fixed outbound departures. In an operational truck scheduling problem, outbound trucks leave the cross dock terminals at predetermined times and delayed loads are kept as inventory that are sent at the next period (a time slot in a day). The proposed model optimizes the inbound truck scheduling problem through the minimizing cross dock operational costs. An accelerated Benders decomposition technique based on Covering Cut Bundle (CCB) strategy and a heuristic approach are developed to solve the model. Finally, numerical analysis introduces the sensitivity of the input parameters to the objective value.
Keywords: Cross dock, scheduling, heuristic algorithm, sensitivity analysis
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