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Exact evaluation of a two-echelon inventory system with a different batch size and information exchange
, Article 37th International Conference on Computers and Industrial Engineering 2007, Alexandria, 20 October 2007 through 23 October 2007 ; Volume 3 , 2007 , Pages 1715-1720 ; 9781627486811 (ISBN) ; Haji, R ; Sharif University of Technology
2007
Abstract
In this paper we consider a dyadic supply chain consisting of one warehouse and one retailer with an unequal order batch size and information exchange. Transportation times are constant and retailer faces independent Poisson demand. The retailer applies continuous review (R,Q)-policy. The supplier starts with m initial batches (of size Q), and places an order in a batch of size nQ to an outside source immediately after the retailer's inventory position reaches R+s. In this paper using the idea of the onefor- one ordering policy we obtain the exact value of the expected system costs
Cost derivation of a dyadic supply chain with time lag information sharing
, Article 37th International Conference on Computers and Industrial Engineering 2007, Alexandria, 20 October 2007 through 23 October 2007 ; Volume 3 , 2007 , Pages 1709-1714 ; 9781627486811 (ISBN) ; Haji, R ; Shenas, N. Y ; Sharif University of Technology
2007
Abstract
In this paper we consider a dyadic supply chain consisting of one warehouse and one retailer with information exchange. We assume that the demand process to the retailer is a Poisson process and transportation times are constant. The retailer applies continuous review (R,Q)-policy. When the retailer's inventory position reaches R+s she sends information about her customer demand and inventory activities to the supplier. The supplier receives this information after a constant time lag. The supplier starts with m initial batches (of size Q), and places an order in a batch of size Q to an outside source immediately after receiving the information from the retailer. In this paper using the idea...
A new discrete time inventory control algorithm for a 2-echelon supply chain
, Article CIE 2014 - 44th International Conference on Computers and Industrial Engineering and IMSS 2014 - 9th International Symposium on Intelligent Manufacturing and Service Systems, Joint International Symposium on "The Social Impacts of Developments in Information, Manufacturing and Service Systems" - Proceedings ; 2014 , pp. 403-411 ; Haji, A ; Haji, R ; Sharif University of Technology
Abstract
Although inventory control under discrete demand in dynamic quantities and time intervals are very common in reality, existing literature has largely ignored them. In this paper, we investigate the inventory control decisions in a two echelon supply chain consists of one vendor and several retailers. The vendor supplies a product to several retailers, buying discrete quantities in pre-determined time intervals. The order quantity and order cycles for each retailer can be different from others. Vendor orders the required quantity from supplier and it'll be immediately received at the vendor's warehouse. In this system, shortage is not allowed for the vendor. The transportation time from the...
A nonlinear model for a capacitated random transportation network
, Article Journal of Industrial and Production Engineering ; Oct , 2015 , Page 500-515 ; 21681015 (ISSN) ; Mahdavi Amiri, N ; Mahdavi, I ; Sharif University of Technology
Taylor and Francis Ltd
2015
Abstract
In this study, we consider a capacitated location–multi-allocation–routing problem with population-dependent random travel times. The objective is to find appropriate locations as server locations among the candidate locations, allocate the existing population in each demand node to server locations, and determine the movement path of each member to reach its corresponding server with respect to the simultaneous change of the random travel times so that the expected total transportation time is minimized. In our study, the concept of population-dependent random travel times incurs two issues: (1) consideration of some random factors in computing the travel times and (2) impact of the...
Vendor's optimal inventory policy with dynamic and discrete demands in an infinite time horizon
, Article Computers and Industrial Engineering ; Volume 102 , 2016 , Pages 368-373 ; 03608352 (ISSN) ; Haji, A ; Haji, R ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Although inventory control under discrete demand in dynamic quantities and time intervals are very common in reality, existing literature has largely ignored them. In this paper, we investigate the inventory control decisions in a two echelon supply chain consisting of one vendor and several retailers. The vendor supplies a product to several retailers, who buy discrete quantities in pre-determined time intervals. The order quantity and order cycles for each retailer can be different from others. Vendor orders the required quantity from supplier and it will be immediately received at the vendor's warehouse. In this system, shortage is not allowed for the vendor. The transportation time from...
A new approach for solution of time dependent neutron transport equation based on nodal discretization using MCNPX code with feedback
, Article Annals of Nuclear Energy ; Volume 133 , 2019 , Pages 519-526 ; 03064549 (ISSN) ; Salehi, A. A ; Vosoughi, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
This paper proposes a new method for solving the time-dependent neutron transport equation based on nodal discretization using the MCNPX code. Most valid nodal codes are based on the diffusion theory with differences in approximating the leakage term until now. However, the Monte Carlo (MC) method is able to estimate transport parameters without approximations usual in diffusion method. Therefore, improving the nodal approach via the MC techniques can substantially reduce the errors caused by diffusion approximations. In the proposed method, the reactor core is divided into nodes of arbitrary dimensions, and all terms of the transport equation e.g. interaction rates and leakage ratio are...
Time Management in a Multi-Modal Routing Problem, Case Study: Rocoland Online Supermarket
, M.Sc. Thesis Sharif University of Technology ; Eshghi, Koroush (Supervisor)
Abstract
Communication growth in today’s world has affected every aspect of our lives. Transportation is an important part of our communication. Traveling, going from one place to another in a city or distribution of goods are examples of transportation. Transportation in which more than one vehicle is used from origin to destination is known as a multimodal transportation. This thesis is about a multimodal transportation problem for distribution of goods. Objective function is to minimize cost and there are constraints on the availability of the fleet. Also, it is possible in our model to use more cars with additional cost when the size of the fleet is not enough. The model is solved by optimization...
Performance control of a tape transport mechanism using entire eigenstructure assignment
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Vol. 10, Issue PART A , 2010 , pp. 133-140 ; ISBN: 9780791843833 ; Hajikolaei, K. H ; Motamedi, M ; Alasty, A ; Sharif University of Technology
Abstract
To achieve high rate of data transfer, tape mechanisms must be able to transport the tape with a constant velocity for scanning. During this process, it is desired to make the rise time minimized without timing and data transfer errors. In this paper, three servo systems including the take-up and supply reel servos for tape tension control and capstan servo for speed control are considered. So, tape transport mechanisms can be described with a nonlinear multi-input multi-output system (MIMO). After state-space representation of the problem, feedback control is designed for tracking objective. It should be mentioned that an increase in the speed of time response of system corresponds to an...
State estimation, positioning and anti-swing robust control of traveling crane-lifter system
, Article Applied Mathematical Modelling ; March , 2015 ; 0307904X (ISSN) ; Vossoughi, G ; Sharif University of Technology
Elsevier Inc
2015
Abstract
Under different loading conditions, the over-head cranes may experience a wide range of model parameters variation. A robust control strategy is developed to achieve the high positioning accuracy, short transportation time and suppression of swing angle for an uncertain over-head crane system. Over-head crane is modeled as a three degrees of freedom system and control problem is investigated for two cases: a system with a single control input (the force on trolley) and a system with two control inputs (the force on trolley and the torque on lifter). Regulator and observer systems are designed. To achieve the tracking objectives, an optimal robust controller is designed based on μ-synthesis...
An exact analysis of a joint production-inventory problem in two-echelon inventory systems
, Article Naval Research Logistics ; Volume 58, Issue 8 , 2011 , Pages 713-730 ; 0894069X (ISSN) ; Berman, O ; Shavandi, H ; Zare, A. G ; Sharif University of Technology
Abstract
We consider a two-echelon inventory system with a manufacturer operating from a warehouse supplying multiple distribution centers (DCs) that satisfy the demand originating from multiple sources. The manufacturer has a finite production capacity and production times are stochastic. Demand from each source follows an independent Poisson process. We assume that the transportation times between the warehouse and DCs may be positive which may require keeping inventory at both the warehouse and DCs. Inventory in both echelons is managed using the base-stock policy. Each demand source can procure the product from one or more DCs, each incurring a different fulfilment cost. The objective is to...
State estimation, positioning and anti-swing robust control of traveling crane-lifter system
, Article Applied Mathematical Modelling ; Volume 39, Issue 22 , 2015 , Pages 6990-7007 ; 0307904X (ISSN) ; Vossoughi, G ; Sharif University of Technology
Elsevier Inc
2015
Abstract
Under different loading conditions, the over-head cranes may experience a wide range of model parameters variation. A robust control strategy is developed to achieve the high positioning accuracy, short transportation time and suppression of swing angle for an uncertain over-head crane system. Over-head crane is modeled as a three degrees of freedom system and control problem is investigated for two cases: a system with a single control input (the force on trolley) and a system with two control inputs (the force on trolley and the torque on lifter). Regulator and observer systems are designed. To achieve the tracking objectives, an optimal robust controller is designed based on μ-synthesis...
Modeling and optimization of generic pull supply chain
, Article Proceedings of the International MultiConference of Engineers and Computer Scientists 2010, IMECS 2010, 17 March 2010 through 19 March 2010, Kowloon ; 2010 , Pages 1738-1742 ; 9789881701282 (ISBN) ; Shokuhyar, Sa ; Shokuhyar, Si ; Sharif University of Technology
2010
Abstract
Nowadays pull system is widely used in many industries. In the recent decade, many researchers adopt pull system to supply chain and present preference of this system. In this paper, a general Pull system for a stochastic supply chain process will be adapted along with optimizing a Pull Stochastic Supply chain. This Supply Chain, SC, is used with combining CONWIP and KANBAN, the two famous pull systems, for controlling the SC. Under assumptions of stochastic demand rate, stochastic production and transportation times, and stochastic distributions for backlog cost, a simulation modeling is used. In optimization process, concerning supply chain complexity, a simulation optimization procedure...
Impact of oil polarity on the mixing time at the pore scale in low salinity waterflooding
, Article Energy and Fuels ; Volume 34, Issue 10 , 16 September , 2020 , Pages 12247-12259 ; Mahani, H ; Ayatollahi, S ; Niasar, V ; Sharif University of Technology
American Chemical Society
2020
Abstract
The efficiency of low salinity waterflooding, particularly during tertiary mode injection, is highly controlled by in situ mixing between the stagnant regions holding high salinity water (HSW) and the flowing regions containing low salinity water (LSW) because it impacts directly the electrokinetics of wettability alteration and the time scale of the low salinity effect. This study aims to address the effects of oil polarity and charged rock surfaces on the time scale of mixing and transport under two-phase flow conditions. A systematic series of micromodel experiments were performed. The micromodels were first saturated with high salinity formation brine and oil (both model and crude oil);...
Due date assignment for multistage assembly systems
, Article Optimization Letters ; Volume 3, Issue 2 , 2009 , Pages 199-210 ; 18624472 (ISSN) ; Kianfar, F ; Sharif University of Technology
2009
Abstract
This paper is concerned with the study of the constant due-date assignment policy in a multistage assembly system. The multistage assembly system is modeled as an open queueing network. It is assumed that the product order arrives according to a Poisson process. In each service station, there is either one or infinite machine with exponentially distributed processing time. The transport times between every pair of service stations are independent random variables with generalized Erlang distributions. It is assumed that each product has a penalty cost that is some linear function of its due-date and its actual completion time. The due date is found by adding a constant to the time that the...