Faculty & Research

Research Productive

Show result

Search Query :
Area :
Search Query :
3846 items in total found

Journal Articles | 2020

Disentangling shock diffusion on complex networks: identification through graph planarity

Sudarshan Kumar, Tiziana Di Matteo, and Anindya S Chakrabarti

Journal of Complex Networks

Large scale networks delineating collective dynamics often exhibit cascading failures across nodes leading to a system-wide collapse. Prominent examples of such phenomena would include collapse on financial and economic networks. Intertwined nature of the dynamics of nodes in such network makes it difficult to disentangle the source and destination of a shock that percolates through the network, a property known as reflexivity. In this article, we propose a novel methodology by combining vector autoregression with an unique identification restrictions obtained from the topological structure of the network to uniquely characterize cascades. In particular, we show that planarity of the network allows us to statistically estimate a dynamical process consistent with the observed network and thereby uniquely identify a path for shock propagation from any chosen epicentre to all other nodes in the network. We analyse the distress propagation mechanism in closed loops giving rise to a detailed picture of the effect of feedback loops in transmitting shocks. We show usefulness and applications of the algorithm in two networks with dynamics at different time-scales: worldwide GDP growth network and stock network. In both cases, we observe that the model predicts the impact of the shocks emanating from the USA would be concentrated within the cluster of developed countries and the developing countries show very muted response, which is consistent with empirical observations over the past decade.

Read More

Journal Articles | 2020

A new solution approach for multi-stage semi-open queuing networks: an application in shuttle-based compact storage systems

Govind Lal Kumawat and Debjit Roy

Computers & Operations Research

Multi-stage semi-open queuing networks (SOQNs) are widely used to analyze the performance of multi-stage manufacturing systems and automated warehousing systems. While there are several methods available for solving single-stage SOQNs, solution methods for multi-stage SOQNs are limited. Decomposition of a multi-stage SOQN into single-stage SOQNs and evaluation of an individual single-stage SOQN is a possibility. However, the challenge lies in obtaining the job departure process information from an upstream single-stage SOQN to evaluate the performance of a downstream single-stage SOQN. In this paper, we propose a two-moment approximation approach for estimating the squared coefficient of variation of the job inter-departure time from a single-stage SOQN, which can serve as an input to link multi-stage SOQNs. Using numerical experiments, we test the robustness of the proposed approach for various input parameter settings for both single and multi-class jobs. We find that the proposed approach works quite well, particularly when the coefficient of variation of the job inter-arrival time is less than two. We demonstrate the efficacy of the proposed approach using a case study on a multi-tier shuttle-based compact storage system and benchmark our results with an existing approach. The results indicate that our approach yields more accurate estimates of the performance measures in comparison to the existing approach in the literature.

Read More

Journal Articles | 2020

Why do institutions revert? Institutional elasticity and petroleum sector reforms in India

Kshitij Awasthi, K. V. Gopakumar, and Abhoy K. Ojha

Business and Society

The institutional change literature has predominantly focused on successful changes and sparsely on failed changes, but the idea of institutional fields reverting to their pre-change or near pre-change state, after change attempts, remains underexplored. Although recent studies have explored similar phenomenon from the perspective of actors resisting change and trying to restore status quo, a field-level understanding of the processes and the dynamics associated with it remains underexamined. The present study, using the case of reforms in the field of petroleum exploration and production in India, examines an institutional change where the institution, once modified, gradually reverted near to its prechange state. We suggest the concept of institutional elasticity to explain such reverting of institutions, and elaborate on three boundary conditions—scope of change, pace of change, and field-level actor constellations—which have implications for the relationship between institutional elasticity and reverting of institutions.

Read More

Journal Articles | 2020

Stochastic modeling of parallel process flows in intra-logistics systems: Applications in container terminals and compact storage systems

Govind Lal Kumawat, Debjit Roy, Rene De Koster, and Ivo Adan

European Journal of Operational Research

Many intra-logistics systems, such as automated container terminals, distribution warehouses, and cross-docks, observe parallel process flows, which involve simultaneous (parallel) operations of independent resources while processing a job. When independent resources work simultaneously to process a common job, the effective service requirement of the job is difficult to estimate. For modeling simplicity, researchers tend to assume sequential operations of the resources. In this paper, we propose an efficient modeling approach for parallel process flows using two-phase servers. We develop a closed queuing network model to estimate system performance measures. Existing solution methods can evaluate the performance of closed queuing networks that consist of two-phase servers with exponential service times only. To solve closed queuing networks with general two-phase servers, we propose new solution methods: an approximate mean value analysis and a network aggregation dis-aggregation approach. We derive insights on the accuracy of the solution methods from numerical experiments. Although both solution methods are quite accurate in estimating performance measures, the network aggregation dis-aggregation approach consistently performs best. We illustrate the proposed modeling approach for two intra-logistic systems: a container terminal with automated guided vehicles and a shuttle-based compact storage system. Results show that approximating the simultaneous operations as sequential operations underestimates the container terminal throughput on average by 28% and at maximum up to 47%. Similarly, considering sequential operations of the resources in the compact storage system results in an underestimation of the throughput capacity up to 9%.

Read More

Journal Articles | 2020

Capacitated multi-period maximal covering location problem with server uncertainty

Amit Kumar Vatsa and Sachin Jayaswal

European Journal of Operational Research

We study the problem of assigning doctors to existing, non-operational Primary Health Centers (PHCs). We do this in the presence of clear guidelines on the maximum population that can be served by any PHC, and uncertainties in the availability of the doctors over the planning horizon. We model the problem as a robust capacitated multi-period maximal covering location problem with server uncertainty. Such supply-side uncertainties have not been accounted for in the context of multi-period facility location in the extant literature. We present an MIP formulation of this problem, which turns out to be too difficult for an off-the-shelf solver like CPLEX. We, therefore, present several dominance rules to reduce the size of the model. We further propose a Benders decomposition based solution method with several refinements that exploit the underlying structure of the problem to solve it extremely efficiently. Our computational experiments show one of the variants of our Benders decomposition based method to be on average almost 1000 times faster, compared to the CPLEX MIP solver, for problem instances containing 300 demand nodes and 10 facilities. Further, while the CPLEX MIP solver could not solve most of the instances beyond 300 demand nodes and 10 facilities even after 20 hours, two of our variants of Benders decomposition could solve instances upto the size of 500 demand nodes and 15 facilities in less than 0.5 hour, on average.

Read More

Journal Articles | 2020

Money, land or self-employment? Understanding preference heterogeneity in landowners’ choices for compensation under land acquisition in India

Vikram Patil, Ranjan Ghosh, Vinish Kathuria, and Katharine N.Farrell

Land Use Policy

Land acquisition policies, upon which future land use patterns in India depend, are controversially tied to the question of whether to provide monetary or non-monetary compensation to affected landowners. However, turning to the preferences of landowners for answers only serves to complicate matters, as these are not homogenous on the question. This implies there is a need to identify the underlying factors giving rise to this preference heterogeneity, in order to develop more effective and efficient policy. This paper aims to address this gap using a contingent ranking experiment to study landowner disposition toward a range of compensation options, presented in a survey conducted in an ‘about-to-be-submerged’ region of a large, multi-stage irrigation project in India. Rankings were based on a selection of six compensation options, constituting different combinations of the attributes - cash, land, housing and self-employment. While the results suggest that landowners generally prefer non-monetary compensation, both the size of landholding and level of education of the landholder appear to influence the preferences for different compensation options. We find that landowners with more land or education tended to favour monetary compensation, while those with lower education or less land tended to favour housing and self-employment options. We close the text by exploring possible explanations for this specific form of heterogeneity, including access to information, to networks and capacities for income generation, and providing some reflections on the implications of these results for ensuring that rehabilitation and resettlement policies are both well targeted and effective.

Read More

Journal Articles | 2020

Evaluating adolescents’ responses to internet ads: Role of ad skepticism, internet literacy, and parental mediation

Meng-Hsien (Jenny) Lin, Russell N. Laczniak, and Akshaya Vijayalakshmi

Journal of Advertising

In this article, we first compare adolescents’ responses to two formats (easily recognizable versus not easily recognizable) Internet ads. We find that Internet literacy and ad skepticism are necessary for adolescents to effectively apply persuasion knowledge to identify both ad formats. Second, we demonstrate that parental mediation and parents’ levels of Internet skills are critical for children’s development of Internet literacy. As a result, this article advances our understanding of adolescents’ responses to different Internet ad formats and the influential role of parental mediation in facilitating children’s development of such skills.

Read More

Journal Articles | 2020

AGV or lift-AGV? Performance trade-offs and design insights for container terminals with robotized transport vehicle technology

Govind Lal Kumawat and Debjit Roy

IISE Transactions

New container terminals are embracing robotized transport vehicles such as lift-automated guided vehicles (LAGVs) and automated guided vehicles (AGVs) to enhance the terminal throughput capacity. Although LAGVs have a high container handling time, they require less coordination with other terminal equipment in comparison with AGVs. In contrast, AGVs are hard-coupled resources, require less container handling times, but operate with high coordination delays in comparison with LAGVs. The effect of such operational trade-offs on terminal performance under various design parameter settings, such as yard block layout and a number of resources, is not well understood and needs to be evaluated at the terminal design phase. To analyze these trade-offs, we develop stylized semi-open queuing network models, which consist of two-phase servers and finite capacity queues. We develop a novel network decomposition method for solving the proposed queuing models. The accuracy of the solution method is validated using detailed simulation models. Using the analytical models, we study the performance trade-offs between the transport vehicle choices: LAGVs and AGVs. Our results show that the throughput capacity of the terminal in the container unloading process increases by up to 16% if LAGVs are chosen as transport vehicles instead of AGVs. However, at certain parameter settings, specifically, when the arrival rate of containers is low, the throughput time performance of the terminal is higher (up to 8%) with AGVs than with LAGVs. We also derive insights on the yard block layout and the technology choice for quay cranes.

Read More

Journal Articles | 2020

Insolvency regimes and firms' default risk under economic uncertainty and shocks

Balagopal, Gopalakrishnan, and Sanket Mohapatra

Economic Modelling

One of the arguments often advanced for implementing a stronger insolvency and bankruptcy framework is that it enhances credit discipline among firms. Using a large cross-country firm-level dataset, we empirically test whether a stronger insolvency regime reduces firms' likelihood of defaulting on their debt. In particular, we examine whether it reduces default risk during increased economic uncertainty and various external shocks. Our results confirm that a stronger insolvency regime moderates the adverse effects of economic shocks on firms' default risk. The effects are more pronounced for firms in the top half of the size distribution. We also explore channels through which improved creditor rights influence firms' default risk, including dependence on external finance, corporate leverage, and managerial ethics. Our main results are robust to an alternative measure of default risk, inclusion of currency and sovereign debt crisis episodes, and alternative estimations.

Read More

Journal Articles | 2020

Apartment buyers as financial creditors: Pushing the conceptual limits of the Indian insolvency regime

M P Ram Mohan and Vishakha Raj

Columbia Journal of Asian Law

A unique feature of the Indian insolvency regime is its
classification of debt into “operational” and “financial” debt. In
Swiss Ribbons v. Union of India, the Supreme Court of India
tenaciously upheld the difference between operational and
financial creditors and declared this classification constitutionally
valid. Last year, the Insolvency and Bankruptcy Code, 2016 (IBC)
was amended to include amounts raised from allottees (persons to
whom an apartment or plot in a real estate project has been
allotted) within the definition of “financial debt,” thus making
allottees financial creditors. Though the amendment was passed to
empower allottees in India’s real estate sector, it revived a more
general discussion on the characteristics of operational and
financial creditors.
This paper posits that the amendment was enacted at the
cost of stretching the definition of “financial creditor” beyond its
conceptual limit and interfering with the IBC’s insolvency
resolution mechanism. We use the United States’ and the United
Kingdom’s insolvency regimes as a point of reference for
ascertaining the role of creditors in insolvency proceedings and
whether operationalizing the insolvency regime to solve problems
in a particular sector is justified.

Read More
IIMA