Uday Venkatadri

State of the art review of quality, reliability and maintenance issues in closed-loop supply chains with remanufacturing

The design of reverse logistics and remanufacturing processes and the recovery of end-of-life products have been well-studied in the literature. Quality, reliability, maintenance and warranty for recovered products and the remanufacturing activities that extend their life are integral issues in reverse logistics. This paper reviews recent and relevant literature on these issues in closed-loop supply chains, with a focus on remanufactured or second-hand products. The published literature is first classified into domain areas of research and practice. The wide array of mathematical tools and techniques used in the literature are then identified and mapped. Finally, the findings are summarised and the main research gaps are highlighted.

A framework for multi-objective facility layout design

Multi-objective meta-heuristic framework for the BLP.Integrating several recent advances in the layout design.More than one possible layout to implement depending on management preferences.Good starting point when faced with a decision about which layout to implement. The most commonly used metric for facility layout design in the academic literature is the flow-distance metric, a weighted average between the material transfer and the distance travelled. Researchers and practitioners, however, have recognized that other metrics are also important. Facility layout designs obtained using the flow-distance metric exclusively have been criticized because they completely ignore empty material transfer, which generally increases work-in-process and equipment costs. Therefore, facility layout design (block layout design in particular) based exclusively on the flow-distance metric is insufficient. In this paper, we present a framework that utilizes the recent advancements in the facility planning literature to generate block layout designs based on three objectives: flow-distance, average work-in-process, and the number of required material handling devices. Numerical experiments are conducted on a number of standard problems, and the tradeoffs between the different objectives are studied. Our study indicates that it is critical to pursue multi-objective analysis and optimization for the actual implementation of the layouts.

A market-driven transfer price for distributed products using mathematical programming☆

A distributed product has its manufacturing activities distributed among many locations. These locations could belong to one or more firms in a manufacturing network. Often, components needed to manufacture a distributed product move through different nodes in the network and sometimes across international borders. Hence, a transfer price is needed for the purpose of estimating duties and drawbacks. Being aware of the fact that transfer price can be used to manipulate taxable profits, many countries have instituted rules concerning transfer price estimation. For example, in the United Sates, the Internal Revenue Service (IRS) says that the right price is the market value. But for many components it is difficult to find a free market. Similar products may exist in the market but they may have different attributes. In such cases, it is important to be able to estimate the market-driven transfer price, given other similar products in the open market.We develop a method using a mathematical programming model and providing companies an opportunity to work proactively with the IRS in a cooperative manner in order to avoid costly audit and litigation. This way, companies avoid penalties and also gain certainty regarding tax liability. An example illustrating the method is presented.

Physical Internet, conventional and hybrid logistic systems: a routing optimisation-based comparison using the Eastern Canada road network case study

The Physical Internet (PI) logistics system is an innovative logistics concept that has been gathering a lot of attention lately. This system consists of open, modular and shared containers and transit hubs to move goods globally. The purpose of this paper is to compare the performance of PI with regard to the conventional (CO) logistics system in order to quantify the advantages and disadvantages of PI from a truck and driver routing perspective with an explicit constraint on maximum return time for drivers. The comparison presented in this work is carried out through Monte-Carlo simulation within a sequential three-phase optimisation framework. Based on our analysis, PI reduces driving distance (and time), GHG (greenhouse gas) emissions and the social cost of truck driving. On the other hand, it increases the number of container transfers within the PI logistics centres. This insight is a contribution of the paper and reinforces the current literature on PI. The other main contribution of the paper is a validation of the claim that the number of drivers who can go back home at the end of a work day remains consistently high in PI, regardless of the traffic level.

Promising orders in supply chain networks

We consider how orders may be promised in a supply chain network. Order promising is increasingly getting attention in both theory and practice due to the proliferation of automated ordering systems. In our model, customers request quotations for a given quantity of products on a due date. The question for a firm is what dates to promise in reply to requests-based on production plans and distribution plans and available capacity. The inputs represent production and distribution data, initial inventories, committed orders and customer due date requests. The outputs of our model are the production quantities in each period and the sourcing path for each product. We show the application of the model to quoting due dates, estimating marginal costs for requests and estimating the maximum availability of products in time periods. The model can be used by companies to promise orders in combination with existing Enterprise Resource Planning (ERP) software.

Optimal selective maintenance decisions for large serial k-out-of-n: G systems under imperfect maintenance

Abstract The selective maintenance problem (SMP) arises in many large multicomponent systems which are operated for consecutive missions interspersed with finite breaks during which only a selected set of component repairs or replacements can be carried out due to limited time, budget, or resources. The problem is to decide which components and degree of repairs should be performed in order to guarantee a pre-specified performance level during the subsequent mission. Current SMP formulations in the literature are nonlinear, deal mainly with basic or series-parallel systems and mostly use heuristic methods to obtain solutions. This paper introduces the first SMP model for serial k-out-of-n systems. Two nonlinear formulations are developed, which can be used to solve the problem for small to moderate size k-out-of-n systems. For large k-out-of-n systems or complex reliability structures, we develop a new two-phase approach which transforms the problem into a multidimensional multiple-choice knapsack problem (MMKP). The new approach is shown to be efficient through multiple sets of numerical experiments.

On Physical Internet Logistics: Modeling the Impact of Consolidation on Transportation and Inventory Costs

The physical Internet (PI) is a conceptual, innovative, and contemporary modular distribution logistics system that has garnered the interest of both researchers and practitioners as an alternative to conventional logistics. It aims to be more environmentally friendly, more socially responsible, and also more profitable. The key concept behind the PI logistics system is the routing of highly modular containers through transit centers (called PI hubs) to obtain a very efficient transport network that exploits consolidation opportunities. A systems model of the traditional and PI networks is developed as an aggregation of optimal point-to-point dispatch models between pairs of cities. This is then used to characterize the behavior of the traditional and PI logistics systems for several different logistics system key performance indicators. Based on the modeling assumptions in this paper, it is concluded that the benefits of the PI are in reducing the inventory cost and the total logistics system cost. However, a fewer truck trips are required in the traditional system, which also has a lower total order delivery time. While the transportation cost in the PI and traditional systems are comparable, the total cost of the PI system is significantly lower.

DSOPP: a platform for distributed simulation of order promising protocols in supply chain networks

This article presents an optimisation-based multi-agent decision support platform (DSOPP) for integrated order promising and production planning in a multi-enterprise supply network environment. The DSOPP platform may be run either in real time or in simulation mode. Its goal is to demonstrate the viability of collaborative decision making. The DSOPP framework is built around a scalable multi-period optimisation model that may be used across enterprises. We first discuss the optimisation model at the core of the planning function called the ‘advanced order planning’ model. We then present the DSOPP platform architecture, which consists of a distributed network control centre (DNCC) and individual supply chain control centres. Intelligent agents are embedded in both types of centres. The role of the DNCC is to coordinate the planning cycle clock and facilitate the transfer of information and inventory through a central mailbox mechanism. An individual supply chain centre comprises agents for demand management, planning and production execution. Results from an experimental case indicate that the ideas presented in this article can be used effectively to coordinate the planning activities across supply chain networks by providing the ability to analyse and understand the effects of various supply chain parameters.

Optimal Combination RebateWarranty Policy with Second-hand Products.

With the increased awareness for sustainability, many engineered products are being recovered and reconditioned for secondary useful lives. These second-hand products can serve as replacement products to honour warranty pledges. This paper presents two mathematical models to determine the optimal combination rebate warranty policy when refurbished products are used for replacements from both the manufacturer and consumer point of views. Several numerical experiments are conducted to derive useful managerial knowledge.

A data-driven approach to multi-product production network planning

Abstract The clearing function models the non-linear relationship between work-in-process and throughput and has been proposed for production planning in environments with queuing (congestion) effects. One approach in multi-product, multi-stage environments has been to model the clearing function at the bottleneck machine only. However, since the bottleneck shifts as the product release mix changes, this approach has its limitations. The other approach is the Alternative Clearing Function formulation, where the clearing function is first estimated at the resource level using piecewise linear regression from simulation experiments, and then embedded into a linear programme. This paper develops an alternative to the Allocated Clearing Function formulation, wherein system throughput is estimated at discrete work-in-process points. A mixed integer programming formulation is then presented to use these throughput estimates for discrete release choices. The strength of the formulation is illustrated with a numerical example and the new approach is compared with the ACF.