Batch Sizing in Sustainable Production Systems with Imperfect Quality

In classic Economic Production Quantity (EPQ), an optimal batch size is determined to minimize total production cost including setup and inventory holding costs, and defective parts are not allowed. In this paper an imperfect EPQ system is studied to minimize the overall cost, where setup cost, scarp rate, batch size, and electrical power demand are determined by the model. In this imperfect production system, a percentage of the batch is defective in each cycle, which will be reworked at an extra charge. In addition, the model considers electrical power demand charge which accounts for a large percentage of industrial utility bills. This framework also determines the optimal level of investment on system design and flexibility which in turn, is a function of setup cost, electrical power requirement (power demand), and scrap rate. The proposed constrained cost minimization problem is formulated as a nonlinear mathematical model, and is solved using a posynomial Geometric Programming (GP) approach to present a closed form solution for the batch size, setup cost, allowable defective rate and power requirements. The model is illustrated through a numerical example and some sensitivity analysis is performed

A lot-sizing model for a multi-state system with deteriorating items, variable production rate, and imperfect quality

Conventional production systems assume that during the manufacturing processes, machines operate without breakdown over an infinite planning horizon and manufacture only products of good quality. Imperfect production processes as a result of machine degradation are common in manufacturing. This paper deals with a problem that concerns the modelling and evaluation of the performance of a multi-state production system that is subject to degradation and its effect on lot sizing. Here, we consider that the cycle starts with a particular production rate until a point when the inventory reaches a certain level after which the failure mode is activated due to the deterioration of certain components, leading to a reduction in the production rate in order to ensure the continuity of supply until the maximum inventory level is reached. Production then stops to restore the machine and the cycle starts again. We have assumed that the rate at which inventory deteriorates is exponential and that demand is constant. A numerical example is used to illustrate the model application, followed by sensitivity analysis. This paper contributes to lot sizing in the area of machine reliability by considering a production system in a degraded state with a non-increasing production rate for deteriorating items with imperfect quality and partial backlogging.http://www.ijmems.inhj2023Industrial and Systems Engineerin

A Lot Sizing Model for a Deteriorating Product with Shifting Production Rates, Freshness, Price, and Stock-Dependent Demand with Price Discounting

Many production systems need to be able to change the rate at which they manufacture products for various reasons, hence, the need to find the optimal lot size under these multiple levels of production. This research addresses the need for optimizing inventory in a system with a shifting production rate and other challenging product characteristics such as product deterioration with limited life span, and product demand that is dependent on the stock level, the state of freshness of the product, and the selling price. The product also needs to be discounted as it gets close to the expiry date in order to boost demand and prevent wastage beyond its life span. Our objective is to maximize profit by determining the optimal selling price and inventory cycle time by deriving the relevant equations for these decision variables. The Newton-Raphson method was used to numerically solve for the optimal values of these variables. Sensitivity analyses were performed to derive useful insights for managerial decision-making

Coordination of pricing, inventory, and production reliability decisions in deteriorating product supply chains

In this article, we study a two-level supply chain model for deteriorating items, in which the supplier’s production system is unreliable and the retailer’s demand is price-sensitive. The supplier’s production line may randomly shift from the in-control state to the out-of-control state. When the production line is in the out-of-control state, a proportion of the produced products will have bad quality. To mitigate the out-of-control risks, the supplier can improve the production line reliability by investing in high-quality machines, highly skilled workers, or advanced maintenance technologies. We start with the study of pricing and inventory problems concerning endogenous reliability in the integrated and decentralised scenario. To better illustrate the proposed models, two applicable algorithms are designed to determine the optimal production reliability, ordering quantity, and prices. Then, a cooperative reliability investment and revenue-sharing contract is proposed to coordinate the supply chain. Numerical examples and sensitivity analysis of the equilibrium strategies and coordinating results on key system parameters (e.g. deterioration rate, production rate, etc.) are given to verify the effectiveness of the contract, and meanwhile get some managerial insights

Η επίδραση πρακτικών HRM στην αποτελεσματική διαχείριση της εφοδιαστικής αλυσίδας

Διπλωματική εργασία--Πανεπιστήμιο Μακεδονίας, Θεσσαλονίκη, 2018.Η παρούσα εργασία ασχολείται με την εξέταση της επίπτωσης των πρακτικών διοίκησης ανθρώπινων πόρων στην επίδοση της εφοδιαστικής αλυσίδας. Στη σημερινή εποχή, η Διοίκηση της Εφοδιαστικής Αλυσίδας έχει καταστεί, ίσως όσο ποτέ άλλοτε, αναπόσπαστο κομμάτι των επιχειρήσεων αλλά η επίπτωση της διοίκησης ανθρώπινων πόρων δεν έχει διερευνηθεί επαρκώς. Από την ανάλυση του ζητήματος σε θεωρητικό και εμπειρικό επίπεδο, προκύπτει ότι από τη σχετική βιβλιογραφία απουσιάζει ένα στέρεο θεωρητικό υπόβαθρο το οποίο θα βοηθούσε, μεταξύ άλλων, στην αποδοτικότερη μελέτη του ζητήματος. Μέσω εμπειρικής έρευνας στα πρότυπα παρόμοιων ερευνών, η εργασία οδηγείται στο συμπέρασμα ότι οι πρακτικές προσέλκυσης και επιλογής ανθρώπινου δυναμικού και η αξιολόγηση της απόδοσης του ανθρώπινου δυναμικού επηρεάζουν σημαντικά την επίδοση της εφοδιαστικής αλυσίδας ανεξαρτήτως του πώς αυτή μετριέται, ενώ αντίθετα, δεν υπάρχει σημαντική επιρροή των πρακτικών εκπαίδευσης-ανάπτυξης του ανθρώπινου δυναμικού και των ανταμοιβών στην επίδοση της εφοδιαστικής αλυσίδας. Παρόμοια, δεν προέκυψε σημαντική σχέση ανάμεσα στα δημογραφικά χαρακτηριστικά και την επίδοση της εφοδιαστικής αλυσίδας, με ελάχιστες εξαιρέσεις. Σε μεθοδολογικό επίπεδο, η παρούσα εμπειρική ανάλυση υποδεικνύει ότι ο τρόπος μέτρησης της επίδοσης της εφοδιαστικής αλυσίδας και των πρακτικών διοίκησης ανθρώπινων πόρων μεταβάλλει σημαντικά τα συμπεράσματα. Η μελλοντική διερεύνηση του υπό εξέταση ζητήματος μπορεί να κινηθεί προς δύο κατευθύνσεις. Αρχικά, η χρήση πιο αντιπροσωπευτικών δειγμάτων θα συνέβαλε στην ενίσχυση της δυνατότητας γενίκευσης των ευρημάτων, κάτι που δεν επιτρέπεται από τον σχεδιασμό της παρούσας έρευνας. Επιπρόσθετα, η χρήση διαφορετικών μεταβλητών ή/ και, γενικά μεθοδολογικού πλαισίου μπορεί να οδηγήσει σε πιο γενικεύσιμα, άρα και αξιοποιήσιμα από την ακαδημαϊκή και την επαγγελματική κοινότητα συμπεράσματα

Hierarchical decision making patterns for the placement of physical supply chain entities

One of the most important areas of development within the evolution of commerce, is the acknowledgement that businesses can no longer compete as individual entities, but rather must function as part of a supply chain. Within an ever-competitive business environment, the ultimate success of a business can often be tied directly to the overall functionality and efficiency of its supply chain. Research within the area of supply chain management is vast, with prior contributions exploring the function of a supply chain from a plethora of social, economic, and commerce perspectives. Prior research has extended to evaluate multiple industries and geographies, over a number of economic and social issues (e.g. environmental sustainability through transport route modification, poverty reduction through global value chain refinement), along with core management and commerce areas (e.g. marketing initiatives through production cycle analysis, operations management through production capacity). Substantial contributions exist which focus on the role of supply chain management and the value of refining, optimizing and designing a chain to the requirements of an industry, economic environment, or business process. In addition to investigation on the definition, function, and applicability of the concept, prior contributions have effectively demonstrated the value of supply chain management in gaining competitive advantage, and improving the overall performance of a business. The notion that supply chain efficiency defines business advantage, has led to exploration of physical configurations and specifications of supply chains; with the primary undertone often centering around evaluating drivers of supply chain optimization, and therein organizational performance. Within existing research, the process of physical site placement, and managerial decision makers within an organization are identified as being key factors in the optimization of a supply chain. As such, a number of prior studies have investigated the drivers which influence physical location decisions, with the majority of research focusing on the impact of geographical location factors. Other studies have centered on the impact of management structure as a catalyst in refining and optimizing a supply chain. While significant research has focused on both areas individually (Barney, 1991; Chopra & Meindl, 2002; Christopher, 1998), relatively little attention has been placed on evaluating the correlation between these paradigms, and therein exploring the root drivers for management decisions. There appears to be substantial value in directly investigating this relationship, as the analysis of this interaction would provide a comprehensive interpretation of specific factors contributing to physical supply chain development decisions. This research evaluated decision making drivers impacting the placement of physical supply chain entities using augmented qualitative and quantitative primary data. One of the main objectives of this study was to define the accepted sequence of decision making priority with respect to land value determination, transportation and accessibility considerations, and tax incentive structures. Data for the study was collected through electronic surveys and interviews, from supply chain managers working at organizations with a minimum annual revenue of $1,000,000 USD. The proposed relationships were evaluated using rigorous statistical analysis including factor analysis and structural equation modelling. Results indicated the existence of a clear sequence in decision structure, with a measurable pattern of priority placed on specific decision criteria. Aspects of corporate culture within the scope of supply chain decision making were explored with insight into the foundation for physical site evaluation. Empirical data suggested the value of land as having the most substantial influence when making physical location decisions. A number of factors influence how managers determine land value, however the location of a site and its proximity to a firms affiliates (e.g. potential partners, strategic alliances) were identified as having the strongest impact. Other considerations including transportation structures, tax incentives, and the ability of a firm to attract highly productive labor also influenced location decisions, albeit to a lesser degree. While prior research suggests businesses often design supply chains with the intention of attracting inexpensive labor, the results of this study were contradictory. Specifically, this study identified a common hierarchical decision making structure, and finds businesses often place value on highly productive labor (not inexpensive labor) when making supply chain location decisions. Fundamentally, the results presented in this study allows firms to gain insight on how decision makers process and interpret information. Establishing the pattern and sequence of decision making priority in the initial physical site placement stage is critical in ascertaining how supply chain networks develop and grow. From an economic standpoint, findings from this study could be applied to competitor assessment, growth planning, and managerial assessment. Based on the notion that competition takes place through supply chain performance, the practical applications of this study provide a meaningful foundation for optimization and therefore competitive advantage. On a larger scale, this contribution is substantial, as it holds value to both academic and business paradigms in further evaluating the definition and optimization potential of a supply chain, and in providing insight into additional areas of business competitiveness