Lot-sizing for inventory systems with product recovery

We study inventory systems with product recovery. Recovered itemsare as-good-as-new and satisfy the same demands as new items. Thedemand rate and return fraction are deterministic. The relevantcosts are those for ordering recovery lots, for orderingproduction lots, for holding recoverable items in stock, and forholding new/recovered items in stock. We derive simple formulaethat determine the optimal lot-sizes for theproduction/procurement of new items and for the recovery ofreturned items. These formulae are valid for finite and infiniteproduction rates as well as finite and infinite recovery rates,and therefore more general than those in the literature.Moreover, the method of derivation is easy and insightful.product returns;recovery;lot sizing;EOQ/EPQ

Valuation of inventories in systems with product recovery

Valuation of inventories has different purposes, in particularaccounting and decision making, and it is not necessary for a firmto use the same valuation method for both purposes. In fact, it isnot uncommon to use accounting books as well as management books.In this chapter, we will only consider inventory values from theperspective of decision making. More specifically, we will analyzethe effect of inventory valuation on inventory control decisions(and not the corresponding financial results) for systems withproduct recovery.

Strategic Issues in Product Recovery Management

This article examines strategic production and operations management issues in product recovery management (PRM). PRM encompasses the management of all used and discarded products, components, and materials for which a manufacturing company is legally, contractually, or otherwise responsible. The objective of PRM is to recover as much of the economic (and ecological) value of used and discarded products, components, and materials as reasonably possible, thereby reducing the ultimate quantities of waste to a minimum. This article also discusses the relevance of PRM to durable products manufacturers. It contains a categorization of PRM decisions. A case study based on the PRM system of a multinational copier manufacturer is presented to illustrate a set of specific production and operations management issues. The experiences of two other pro-active manufacturers (BMW and IBM) are also discusse

Modelling and optimisation of a product recovery network

An appropriate logistics network is an important element of the infrastructure of any product recovery company. Small and medium enterprises (SMEs) constitute a major fraction of the product recovery industry with a different business objective and scale of operation from those of original equipment manufacturers. This paper addresses the network design issues for SMEs involved in product recovery activities. A mathematical formulation is presented in an SME context and a subsequent simulation model is developed. A genetic algorithm approach is presented for optimising the network for a single product scenario

Dynamic buy-back for product recovery in end-of-life spare parts procurement

The efficient supply of spare parts is of prime concern for OEMs. Next to the traditional spare parts sources in form of final order and remanufacturing, the option to buy back broken products prevents the OEM from fulfilling his spare parts availability obligation in the end-of-life phase and increases his ability to remanufacture. This contribution seeks to identify optimal buy-back strategies for different settings regarding information availability and buy-back flexibility. A numerical study analyzes circumstances under which buy-back is especially beneficial for the OEM.Inventory Management, Spare Parts Management, Reverse Logistics, Buy-back

In situ Product Recovery Integrated with Biotransformations

Biocatalysis constitutes an effective tool for the production of fine chemicals. In order to widen the spectrum of applicable reaction types to reactions that are constrained by inhibitions, product toxicity, or degradation, an unfavorable position of the thermodynamic equilibrium, or by kinetic control, in situ product removal (ISPR) is an attractive process option to overcome those limitations. To fully exploit the benefits of the ISPR approach, selective removal of the product to an auxiliary phase with high capacity is usually required. Obviously, such an operation becomes increasingly difficult with decreasing differences in the physical properties of substrate(s) and product(s) as it is arguably frequently the case with biotransformations. In this paper we analyze the possibilities to apply ISPR to biotransformations and identify the most promising developments supported by simple model considerations to fully exploit the potential of ISPR

Polyether Product Recovery: Salt-Induced Water-Polymer Separation

Evonik Industries currently loses approximately 50 tons of polyether product to wastewater washes annually. Evonik has requested an industrially viable solution to maximize the recovery of the lost product in the current process. It was required that the solution have a one year payback period, and be in compliance with current regulatory policies. Literature sources showed that salt is a commonly used agent to force the separation of polyether-water mixtures. Using this information, a method was developed using a salt already present in the process to induce a phase separation and to recover the polyether. An empirical multilinear refractive index model was developed to determine the polyether content in treated samples, while thermogravimetric analysis (TGA) was used to determine the salt content. A series of preliminary tests followed trends observed in academia, which claimed that salt composition and temperature had an effect on the amount of polyether recovered. A design of experiment (DoE) was performed on three classes of Evonik’s polyether to determine the optimum conditions for product recovery on a bench scale. Using the optimal recovery region from the DoE, a scale up was performed, and two other tests were performed to examine the effect of reducing the water used in the washes. In both cases, 88-99% of the polymer could be recovered, although the reduced-water trials required an order of magnitude less salt than the full-wash trials. From these results, it is expected approximately $130,000 of product could be recovered annually with an initial investment of$46,500.https://scholarscompass.vcu.edu/capstone/1089/thumbnail.jp

Lot-sizing for inventory systems with product recovery

We study inventory systems with product recovery. Recovered items are as-good-as-new and satisfy the same demands as new items. The demand rate and return fraction are deterministic. The relevant costs are those for ordering recovery lots, for ordering production lots, for holding recoverable items in stock, and for holding new/recovered items in stock. We derive simple formulae that determine the optimal lot-sizes for the production/procurement of new items and for the recovery of returned items. These formulae are valid for finite and infinite production rates as well as finite and infinite recovery rates, and therefore more general than those in the literature. Moreover, the method of derivation is easy and insightful

Electrogenerated N-Heterocyclic Carbene in Ionic Liquid: An Insight into the Mechanism of the Oxidative Esterification of Aromatic Aldehydes

An N-heterocyclic carbene (NHC), generated by cathodic reduction of BMImBF4, mediates the oxidative esterification of aromatic aldehydes with organic bromides in the corresponding ionic liquid as solvent. The product recovery by simple extractive work-up with diethyl ether allowed the ionic liquid to be recycled up to 9 times for subsequent electrolyses, with no significant loss in the product yield. The isolation of an intermediate, whose structure was confirmed by synthesis and transformation into the ester, provided the key for a mechanistic insight into the reaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Valuation of inventories in systems with product recovery

Valuation of inventories has different purposes, in particular accounting and decision making, and it is not necessary for a firm to use the same valuation method for both purposes. In fact, it is not uncommon to use accounting books as well as management books. In this chapter, we will only consider inventory values from the perspective of decision making. More specifically, we will analyze the effect of inventory valuation on inventory control decisions (and not the corresponding financial results) for systems with product recovery