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3721 items in total found

Journal Articles | 2019

Integrated storage-order picking systems: Technology, performance models, and design insights

ElenaTappiaa, Debjit Roy, MarcoMelacini, and René De Koster

European Journal of Operational Research

In many warehouses shuttle-based technologies have replaced the traditional AS/R system based storage technologies. The impact these systems have on downstream order picking performance is largely unknown. To study the interactions between upstream storage and downstream picking systems, we develop a novel analytical model for integrated storage and order picking systems. The resulting semi-open queuing model is solved using the matrix-geometric method. Using the queuing network model, we are able to study the effect of storage system technology on order throughput times, and the effect of the picking station input buffer size on order picking performance. Further, we analyze the effect of a constant work-in-process (CONWIP) control for orders on system performance. Our results indicate that using SBS/R instead of AS/R-based storage systems yields investment cost savings (i.e., fewer aisles in the storage area and fewer picking stations), paired with a lower total throughput time at a given order arrival rate. Numerical studies show how the total throughput time, first, benefits and then becomes stable by increasing the input buffer size at the picking stations. Retrieving item tote at the storage system in advance with respect to the picker availability is also advantageous, especially in the SBS/R system.

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Journal Articles | 2019

Inventory allocation in robotic mobile fulfillment systems

Tim Lamballais Tessensohn, Debjit Roy, and Rene B M De Koster

IISE Transactions

A Robotic Mobile Fulfillment System is a recently developed automated, parts-to-picker material handling system. Robots can move storage shelves, also known as inventory pods, between the storage area and the workstations and can continually reposition them during operations. This article shows how to optimize three key decision variables: (i) the number of pods per SKU; (ii) the ratio of the number of pick stations to replenishment stations; and (iii) the replenishment level per pod. Our results show that throughput performance improves substantially when inventory is spread across multiple pods, when an optimum ratio between the number of pick stations to replenishment stations is achieved and when a pod is replenished before it is completely empty. This article contributes methodologically by introducing a new type of Semi-Open Queueing Network (SOQN): cross-class matching multi-class SOQN, by deriving necessary stability conditions, and by introducing a novel interpretation of the classes.

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Journal Articles | 2019

Robotized and automated warehouse systems: Review and recent developments

Kaveh Azadeh, Debjit Roy, and Rene De Koster

Transportation Science

Robotic handling systems are increasingly applied in distribution centers. They require little space, provide flexibility in managing varying demand requirements, and are able to work 24/7. This makes them particularly fit for e-commerce operations. This paper reviews new categories of automated and robotic handling systems, such as shuttle-based storage and retrieval systems, shuttle-based compact storage systems, and robotic mobile fulfillment systems. For each system, we categorize the literature in three groups: system analysis, design optimization, and operations planning and control. Our focus is to identify the research issue and operations research modeling methodology adopted to analyze the problem. We find that many new robotic systems and applications have hardly been studied in academic literature, despite their increasing use in practice. Because of unique system features (such as autonomous control, flexible layout, networked and dynamic operation), new models and methods are needed to address the design and operational control challenges for such systems, in particular, for the integration of subsystems. Integrated robotic warehouse systems will form the next category of warehouses. All vital warehouse design, planning, and control logic, such as methods to design layout, storage and order-picking system selection, storage slotting, order batching, picker routing, and picker to order assignment, will have to be revisited for new robotized warehouses.

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Journal Articles | 2019

Identifying defective network components through restricted group testing

Diptesh Ghosh

OPSEARCH

In this paper, we consider a network of switches in which some of the switches may malfunction. Our aim is to find out efficiently (a) if any of the switches in a network of switches are defective, and (b) if there are defective switches, to identify those switches. We find an optimal solution for the first problem and a heuristic solution to the second, and demonstrate the feasibility of our approach through computational experiments.

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Journal Articles | 2019

Strategizing in small informal retailers in India: Home delivery as a strategic practice

Atul Arun Pathak and George Kandathil

Asia Pacific Journal of Management

Small informally organized family-owned grocery retailers—kiranas—are ubiquitous in India and have retained market dominance while facing increasing competition from large formally organized retailers (FORs). Yet, strategy literature has under-explored such informal businesses. We explore kiranas’ distinct strategic practices that give them competitive advantage over FORs, generating kiranas’ sustained market dominance. To explore kiranas’ informal strategizing, grounded theoretic analysis of our multi-year case study suggested the employment of strategy as practice (SAP) framework, enriched with the social exchange theory (SET) concepts of trust and reciprocity. We find that the kiranas’ sustained enactment of strategic practice such as free-of-charge home-delivery significantly depends on contextually rich, reciprocity-based social exchange relationships with customers which evolve through praxes involving continuous exchange of trust. The practice enactment and exchange relationships constitute strategy-practitioner’s emerging dual-identity, which in turn reinforces the practices, generating a self-reinforcing cycle of practice enhancement. Within this cyclic relationship, an inimitable enactment of a strategic practice can be a key source of competitive advantage for informally organized small retail retailers over large FORs. By linking two unconnected prominent approaches to understanding patterns of workplace interactions, namely SAP and SET, the study opens theoretical avenues for exploring strategizing of informal businesses.

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Journal Articles | 2019

Non-optimality of state by state monopoly pricing with demand uncertainty: An example

James Peck and Jeevant Rampal

Economics Letters

This paper considers a monopoly’s profit maximizing problem, where there is a continuum of consumers with unit demand, and valuations are given by one of two possible demand distributions/states. The firm’s problem is to maximize profits by choosing an optimal mechanism among direct revelation mechanisms that satisfy interim incentive compatibility and ex-post individual rationality. We show that setting the monopoly price in each demand state may not be optimal.

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Journal Articles | 2019

An examination of factors driving big 4 audit fee premiums: Evidence from India's audit market

Joshy Jacob, Naman Desai, and Sobhesh Kumar Agarwalla

Accounting Horizons

This study examines fee premiums earned by Big 4 auditors in India and identifies the primary reason for such fee premiums. There are three primary drivers of Big 4 fee premiums. Big 4 auditors charge a fee premium for their reputation, for providing a superior quality of audit, and for indemnifying losses for a company's stakeholders. Since the risk of auditor litigation in India is relatively low, Big 4 premiums in India would not be driven by the need for auditors to indemnify losses. The results indicate that Big 4 auditors earn significantly higher fees in India and also that their clients enjoy significantly higher earnings response coefficients compared to non-Big 4 clients. However, there is no difference in the quality of audit provided by Big 4 and non-Big 4 auditors as measured by the magnitude of reported discretionary accruals.

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Journal Articles | 2019

Trust in humanitarian operations: a content analytic approach for an Indian NGO

Prakash Awasthy, K.V. Gopakumar, Sirish Kumar Gouda, and Tanushree Haldar

INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH

Trust between partners, a key element enabling coordination across supply chains, has recently started gaining attention in humanitarian operations literature. Yet, empirical examination of this concept is scant. Borrowing from extant literature on trust within organisational behaviour stream, this paper aims to empirically verify trust formation types: companion, competence and commitment, in a disaster relief supply chain using primary and secondary data from an Indian Humanitarian relief organisation (HRO). Further, we identify variations in trust formation during disaster relief activities and developmental programmes, and between upstream and downstream partners of a humanitarian relief organisation. Based on the results of our content analysis, we contend that while companion based trust is significantly more prevalent during developmental programmes, competence based trust is important during both disaster periods and otherwise. We also find that there are significant differences in the trust formation between upstream and downstream partners and the HRO. This study has significant theoretical and practical implications on identifying the role of trust in humanitarian operations.

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Journal Articles | 2019

Can subordinate voice prevail with abusive supervision? A conceptual model using conservation of resources perspective

K.V. Gopakumar and Sweta Singh

Management Research Review

Purpose

Drawing from conservation of resources (COR) theory, this study aims to explain why certain voice types prevail while other voice types are inhibited in the presence of abusive supervision.

Design/methodology/approach

This paper surveys extant literature on abusive supervision, employee voice and COR theory and provides propositions linking abusive supervision and types of voice behaviours.

Findings

The paper develops a conceptual model linking abusive supervision and three types of subordinate voice behaviours – prosocial, defensive and acquiescent voices. It identifies psychological distress as a mediator and locus of control as a moderator to this relationship.

Originality/value

This paper deepens our present understanding of abusive supervision and voice relationship by explaining why only certain voice types prevail with abusive supervision while others do not. While extant literature concluded abusive supervision only as an inhibitor of voice behaviours, the present study identifies how abusive supervision could both inhibit and motivate different voice behaviours. Further, it links abusive supervision to multiple voice types, diverting from extant literature linking abusive supervision to only constructive voice. Lastly, this study contributes to resource acquisition strategies within COR theory.

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Journal Articles | 2019

Impact of regulatory framework on bidding behavior of firms: Policy implications for the oil & gas sector

Sunil Sharma and Mukesh Sud

Energy Policy

India's economy is heavily dependent on foreign oil with the country importing nearly 80% of its crude requirement. Consequently, government of India has been keen to encourage private investment in this sector through attractive policy frameworks. The earlier New Exploration Licensing Policy (1999–2015) has met with limited success, especially in the context of attracting multinational firms, necessitating its replacement with Open Acreage Licensing Policy. The factors that resulted in the limited success of a regulatory framework are not fully understood, especially the impact of firms bidding behavior. This paper adopts a qualitative approach to examine bidding decisions of four petroleum exploration firms across several bidding rounds from a resource picking mechanism perspective. Our findings suggest that uncertainties in the regulatory framework were exploited by the firms resulting in policy inefficacy. Our research identifies four variants of uncertainties and three types of aggressive bidding behavior. We recommend that in order to increase policy efficacy, there is a need to decrease stance uncertainty. Further adoption of a behavioral strategy lens to examine regulatory policy can inform the extant literature.

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