The vendor location problem

Cataloged from PDF version of article.The vendor location problem is the problem of locating a given number of vendors and determining the number of vehicles and the service zones necessary for each vendor to achieve at least a given profit. We consider two versions of the problem with different objectives: maximizing the total profit and maximizing the demand covered. The demand and profit generated by a demand point are functions of the distance to the vendor. We propose integer programming models for both versions of the vendor location problem. We then prove that both are strongly NP-hard and we derive several families of valid inequalities to strengthen our formulations. We report the outcomes of a computational study where we investigate the effect of valid inequalities in reducing the duality gaps and the solution times for the vendor location problem

The vendor location problem

The vendor location problem is the problem of locating a given number of vendors and determining the number of vehicles and the service zones necessary for each vendor to achieve at least a given profit. We consider two versions of the problem with different objectives: maximizing the total profit and maximizing the demand covered. The demand and profit generated by a demand point are functions of the distance to the vendor. We propose integer programming models for both versions of the vendor location problem. We then prove that both are strongly NP-hard and we derive several families of valid inequalities to strengthen our formulations. We report the outcomes of a computational study where we investigate the effect of valid inequalities in reducing the duality gaps and the solution times for the vendor location problem. © 2011 Elsevier Ltd. All rights reserved

Kajian Karakteristik Lokasi Pedagang Kaki Lima di Kawasan Pendidikan Gunungpati di Kota Semarang

Street vendor can be found in downtown city, including education area. That also applies in education area of Semarang, such as Gunungpati Region. The emergence of street vendor in Gunungpati region makes a fairly high density environment which is less in order. To answer this problem, the purpose of this research can be formulated as to identify the characteristics of street vendor location in education area.The target to achieve the goal is to identify the activity and bussiness opportunity of street vendorr, consumer profile, consumer perception in the presence of street vendor, and to formulate the characteristics of the street vendor location around education area in Gunungpati by street vendor and consumer perception. The method of this research uses descriptive quantitative approach, comparative descriptive, frequency distribution and crosstab (cross-tabulations). The data collection method is by primary data in the form of questionnaire, field observation and secondary data in the form of documentation. Sampling method for street vendor population is by using stratified random sampling while the sample for the population of consumer is by using accidental sampling technique. The output produced from this research is to identify the characteristics of street vendor location in education area of Gunungpati influenced characteristics in education area of Gunungpati is affected predominantly by existing primary activities such as education and housing facility

An evolutionary approach for multi-objective optimization of the integrated location-inventory distribution network problem in vendor-managed inventory

[[abstract]]Vendor-managed inventory (VMI) is one of the emerging solutions for improving the supply chain efficiency. It gives the supplier the responsibility to monitor and decide the inventory replenishments of their customers. In this paper, an integrated location-inventory distribution network problem which integrates the effects of facility location, distribution, and inventory issues is formulated under the VMI setup. We presented a Multi-Objective Location-Inventory Problem (MOLIP) model and investigated the possibility of a multi-objective evolutionary algorithm based on the Non-dominated Sorting Genetic Algorithm (NSGA2) for solving MOLIP. To assess the performance of our approach, we conduct computational experiments with certain criteria. The potential of the proposed approach is demonstrated by comparing to a well-known multi-objective evolutionary algorithm. Computational results have presented promise solutions for different sizes of problems and proved to be an innovative and efficient approach for many difficult-to-solve problems.[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

Optimal Supply Network with Vendor Managed Inventory in a Healthcare System with RFID Investment Consideration

Supply Chain Management in the healthcare sector faces several significant challenges, including complexity in healthcare systems, high supply chain costs, balancing quality and costs, delay in delivery, product availability from vendors, inventory waste, and unpredictability and uncertainty. Among those challenges, having an effective inventory management system with an optimal supply network is important to improve the match between supply and demand, which would improve the performance of for healthcare firms. Vendor Managed Inventory (VMI) system is a replenishment solution in which the vendor monitors and decides the time and the quantity of the inventory replenishment of their customers subject to their demand information exchange. A VMI contract in the location-inventory assignment problem is a decision tool for management in the healthcare industry, in which it enables the management to have a cost and service effective decision tool to critically re-evaluate and examine all areas of operations in a SC network looking for avenues of optimization. This dissertation is based on a real-world problem arising from one of the world\u27s leading medical implant supply company applied to a chain of hospitals in the province of Ontario. The chain of hospitals under study consists of 147 hospitals located in Ontario, Canada. The vendor is a supplier of three types of medical implants (a heart valve, an artificial knee, and a hip). In Chapter 2 of this dissertation, we present an optimal supply healthcare network with VMI and with RFID consideration, in which we shed light on the role of the VMI contract in the location-inventory assignment problem and integrate it with both the replenishment policy assignment and the Radio Frequency Identification (RFID) investment allocation assignment in healthcare SC networks using both VMI and direct delivery policies. A numerical solution approach is developed in the case of the deterministic demand environment, and we end up with computational results and sensitivity analysis for a real-world problem to highlight the usefulness and validate the proposed model. We extend our research of integrating the VMI contract in the location-inventory assignment problem with the replenishment policy assignment under a deterministic demand environment to include the stochastic demand environment. The impact of the uncertainty of the demand as a random variable following two types of distributions, normal and uniform distributions, is studied in Chapter 3. Motivated by the lack of investigations and comparative studies dealing with the preference of dealing with VMI contracts to other traditional Retailer Managed Inventory (RMI) systems, we provide in Chapter 4 of this dissertation a comparative study in which we compare the total cost of the VMI system with another two situations of traditional RMI systems: first, a traditional RMI system with a continuous replenishment policy for all hospitals and with assigned storage facilities and second, a traditional RMI system with a direct delivery policy for all hospitals without assigning a storage facility. Computational results, managerial insights, sensitivity analysis, and solution methodologies are provided in this dissertation. Keywords: Vendor Managed Inventory, healthcare system, location-inventory, RFID technology, supply-chain network, stochastic demand, location-inventory assignment problem, and retailer managed Inventory

Vendor location problem

Ankara : The Department of Industrial Engineering and the Institute of Engineering and Science of Bilkent University, 2009.Thesis (Master's) -- Bilkent University, 2009.Includes bibliographical references leaves 45-46.In this study, we aim to design a distribution system with the following components: the location of vendors, the number of vendors, the service region of the vendors, the number of vehicles and workers, and the assignment of demand points to these vendors and vehicles. We define our problem as a two-level capacitated discrete facility location problem with minimum profit constraints and call it Vendor Location Problem. In order to formulate the problem, two different objective functions are used: vendors’s profit maximization and maximization of the demand covered. Integer linear programs for these two versions of the problem are formulated. Valid inequalities are used to strengthen the upper bounds. Finally, the performance of these models with different parameters are compared in terms of linear programming relaxation gap, optimality gap, CPU time, and the number of opened nodes for four different types of instances: instances with demand and profit which are independent of distance; profit function of distance; demand function of distance; demand and profit function of distance.Çınar, YüceM.S

Perancangan Aplikasi E-Commerce Dengan Sistem Rekomendasi Item-Based Collaborative Filltering

PD Damai Motors is one company in the town of Bandar Lampung engaged in the sale of spare parts, however, the system is running right now, there are still many problems that occur both on the vendor and on the part of consumers, especially outside the city of Bandar Lampung. The vendor has not had a special media to promote a product - products and recording sales transactions reports are done manually using only existing proof of the transaction. And consumers still have to directly come to the store if you want to get information about products and want to order the products according to the desired design, as well as the consumer should contact the vendor via sms / call if you want to know the progress of the production order. Scientific report will describe and explain the design Application E-Commerce system with Item-Based Collaborative Filltering clearly so that can know the location of the problem. In analyzing the system, the authors use analytical tools such as Document Flow Diagram (flowchart) and Unified Modeling Language (UML)XV + 60 + Attachment Refrence

A new VRPPD model and a hybrid heuristic solution approach for e-tailing

We analyze a business model for e-supermarkets to enable multi-product sourcing capacity through co-opetition (collaborative competition). The logistics aspect of our approach is to design and execute a network system where “premium” goods are acquired from vendors at multiple locations in the supply network and delivered to customers. Our specific goals are to: (i) investigate the role of premium product offerings in creating critical mass and profit; (ii) develop a model for the multiple-pickup single-delivery vehicle routing problem in the presence of multiple vendors; and (iii) propose a hybrid solution approach. To solve the problem introduced in this paper, we develop a hybrid metaheuristic approach that uses a Genetic Algorithm for vendor selection and allocation, and a modified savings algorithm for the capacitated VRP with multiple pickup, single delivery and time windows (CVRPMPDTW). The proposed Genetic Algorithm guides the search for optimal vendor pickup location decisions, and for each generated solution in the genetic population, a corresponding CVRPMPDTW is solved using the savings algorithm. We validate our solution approach against published VRPTW solutions and also test our algorithm with Solomon instances modified for CVRPMPDTW

An Economic Study of the Effect of Android Platform Fragmentation on Security Updates

Vendors in the Android ecosystem typically customize their devices by modifying Android Open Source Project (AOSP) code, adding in-house developed proprietary software, and pre-installing third-party applications. However, research has documented how various security problems are associated with this customization process. We develop a model of the Android ecosystem utilizing the concepts of game theory and product differentiation to capture the competition involving two vendors customizing the AOSP platform. We show how the vendors are incentivized to differentiate their products from AOSP and from each other, and how prices are shaped through this differentiation process. We also consider two types of consumers: security-conscious consumers who understand and care about security, and na\"ive consumers who lack the ability to correctly evaluate security properties of vendor-supplied Android products or simply ignore security. It is evident that vendors shirk on security investments in the latter case. Regulators such as the U.S. Federal Trade Commission have sanctioned Android vendors for underinvestment in security, but the exact effects of these sanctions are difficult to disentangle with empirical data. Here, we model the impact of a regulator-imposed fine that incentivizes vendors to match a minimum security standard. Interestingly, we show how product prices will decrease for the same cost of customization in the presence of a fine, or a higher level of regulator-imposed minimum security.Comment: 22nd International Conference on Financial Cryptography and Data Security (FC 2018