Closed-loop supply chains: What reverse logistics factors influence performance?

This paper analyses the inventory and order flow dynamics in closed-loop supply chains (CLSCs). In this kind of supply chains the reverse flow of materials entering the system for recycling purposes complicates the way in which inventories should be managed and replenishment policies should be designed. Specifically, we analyse the relationships between some reverse logistics' factors (remanufacturing lead-time, return rate of recycled products, reverse order policy, and number of supply chain tiers) on the order and inventory variance amplification. We firstly perform a systematic literature review of the related studies. Secondly, by adopting a difference equation math approach and design of experiment we perform a robust what-if analysis of a CLSC under a variety of operational and market conditions. Results show that, ceteris paribus, CLSC outperforms a forward supply chain, both in mono-echelon and multi-echelon structures and under both stationary and turbulent market demands. Furthermore, reducing remanufacturing lead-time and promoting information transparency may be crucial to improve CLSC dynamics. Finally, we use the research findings to provide interesting managerial consideration about how to reduce unnecessary operational members' costs

Achieving convergence in galaxy formation models by augmenting N-body merger trees

Accurate modeling of galaxy formation in a hierarchical, cold dark matter universe requires the use of sufficiently high-resolution merger trees to obtain convergence in the predicted properties of galaxies. When semi-analytic galaxy formation models are applied to cosmological N-body simulation merger trees, it is often the case that those trees have insufficient resolution to give converged galaxy properties. We demonstrate a method to augment the resolution of N-body merger trees by grafting in branches of Monte Carlo merger trees with higher resolution, but which are consistent with the pre-existing branches in the N-body tree. We show that this approach leads to converged galaxy properties

Inventory record inaccuracy in supply chains: the role of workers’ behavior

Purpose This research aims at exploring the effect of inventory record inaccuracy due to behavioral aspects of workers on the order and inventory variance amplification. Design/methodology/approach We adopt a continuous-time analytical approach to describe the effect of inbound throughput on the inventory and order variance amplification due to the workload pressure and arousal of workers. The model is numerically solved through simulation and results are analyzed with statistical general linear model. Findings Inventory management policies that usually dampen variance amplification are not effective when inaccuracy is generated due to workers’ behavioral aspects. Specifically, the psychological sensitivity and stability of workers to deal with a given range of operational conditions have a combined and multiplying effect over the amplification of order and inventory variance generated by her/his errors. Research limitations/implications The main limitation of our research is that we model workers’ behavior by inheriting a well-known theory from psychology that assumes a U-shaped relationship between stress and errors. We do not validate this relationship in the specific context of inventory operations. Practical implications The paper gives suggestions for managers who are responsible for designing order and inventory policies on how to take into account workers’ behavioral reaction to work pressure. Originality/value The logistics management literature does not lack of research works on behavioral decision making causes of order and inventory variance amplification. Contrarily, this paper investigates a new kind of behavioral issue, namely the impact of psycho-behavioral aspects of workers on variance amplification

Absorption of Impact Forces by Three Types of Equestrian Protective Vests

Please view abstract in the attached PDF file

Methodological approach to study the dynamics of production networks: Discrete-event simulation modelling

This paper shows how discrete-event simulation represents an appropriate tool for approaching the dynamics of production networks. Three important factors influencing production network dynamics, specifically finite production capacity, manufacturing lead time, and its variability are discussed and a basic discrete-event simulation model is presented. Such model, which in its basic form represents a simple retail/distribution two-stage supply chain, is then extended in order to take into account those factors that can not be included in a classical control theoretical model

On the bullwhip avoidance phase: the synchronized supply chain

The aim of this paper is to analyse the operational response of a Synchronised Supply Chain (SSC). To do so, first a new mathematical model of a SSC is presented. An exhaustive Latin Square design of experi- ments is adopted in order to perform a boundary variation analysis of the main three parameters of the periodic review smoothing (S,R) order-up-to policy: i.e., lead time, demand smoothing forecasting factor, and proportional controller of the replenishment rule. The model is then evaluated under a variety of performance measures based on internal process benefits and customer benefits. The main results of the analysis are: (I) SSC responds to violent changes in demand by resolving bullwhip effect and by creating stability in inventories under different parameter settings and (II) in a SSC, long production\u2013 distribution lead times could significantly affect customer service level. Both results have important consequences for the design and operation of supply chains

Combining Qualitative Research Perspectives and Methods for Critical Social Purposes The Neoliberal U.S. Childhood Public Policy Behemoth

This article discusses the broad-based use of bricolage to examine the neoliberal childhood policy discourses and forms of implementation that are currently practiced in the United States. Diverse, traditionally marginalized understandings such as Black feminist thought, Chicana feminism, and feminist analysis of capitalist patriarchy are combined with a Deleuze/Guattarian critique of capitalism and qualitative methods of situational analyses. We do this to identify childhood assemblages within the childhood public policy behemoth in the United States and compare these assemblages to capitalism more broadly, including how neoliberal practices are facilitated

Capacitance study of thin film SnO2:F/p-type a-Si:H heterojunctions

Abstract We characterized SnO 2 :F/p-type a-Si:H heterojunctions by current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature to determine the junction parameters. Samples with circular geometry and different diameters were characterized. The current scales with the junction area, and the current density J as a function of the voltage V is a slightly asymmetric curve with a super-linear behaviour (cubic law) for high voltages. Using a transmission line model valid for devices with circular geometry, we studied the effects of the SnO 2 :F resistivity on the measured capacitance when the SnO2:F layer works as an electrical contact. The measured C-V curve allows us to determine junction parameters as doping of p-type a-Si:H, built-in potential and depletion width for the heterojunction with the smallest diameters, demonstrating that for these samples the TCO effects can be neglected. We compared theoretical and measured data to explain qualitatively the transport mechanism in this heterojunction