Suchergebnisse

AbstractWhen demand exceeds supply, retailers hedge against shortages by placing multiple orders with multiple suppliers, exceeding customer demand and leading to excess capacity, excess inventory, low capacity utilization and financial losses. This paper provides a comprehensive causal loop diagram and a formal mathematical model of a subset of supplier–retailer relationships. We obtain closed‐form solutions when supplier capacity is fixed, and analyze simulation dynamics when it is variable. Sensitivity analyses provide a deeper understanding of parameters that contribute to demand bubbles and insight on improvement policies. For instance, the ability of the supplier to build capacity quickly can reduce bubble size. The time it takes retailers to perceive and react to supply availability is an important lever in controlling demand bubbles. When retailers learn of shortages with a delay, their reaction is also delayed, which stabilizes the supply chain.© 2018 System Dynamics Society

AbstractOne of the most fundamental principles in system dynamics is the premise that the structure of the system will generate its behavior. Such a philosophical position has fostered the development of a number of formal methods aimed at understanding the causes of model behavior. Behavior, to most in the field of system dynamics, is commonly interpreted as modes of behavior (e.g., exponential growth, exponential decay, and oscillation) because of their direct association with the feedback loops (e.g., reinforcing, balancing, and balancing with delays, respectively) that generate them. Hence, traditional research on formal model analysis has emphasized which loops cause a particular "mode" of behavior, with eigenvalues representing the most important link between structure and behavior. The main contribution of this work arises from a choice to focus our analysis on the overall trajectory of a state variable, instead of only a specific behavior mode. Since the overall behavior trajectory of state variable xi(t) is determined by a linear combination of the product of eigenvector components (rji) and behavior modes ($e^{l_jt}$) generated by eigenvalues (λj), contributions from both eigenvalues and eigenvectors are important. By studying how the overall trajectory changes due to changes in link (or loop) gains, we observe that the derivatives of eigenvectors are more closely associated with the short‐term transient impact of those changes, whereas derivatives of eigenvalues are associated with the long‐term impact. Since we care deeply about both the short‐ and the long‐term impact of those changes, there is value in looking at the contributions from both eigenvalues and eigenvectors. Copyright © 2009 John Wiley & Sons, Ltd.

O trabalho sob contrato tornou-se importante estratégia para obtenção de trabalhadores precarizados ao longo do século XIX à sombra do escravismo, provocando o deslocamento de contingentes populacionais significativos. No contexto do pós-abolição da escravidão colonial francesa e da proibição do comércio de escravizados, este artigo analisa o tráfico de trabalhadores engajados de Moçambique para a Ilha Reunião através do caso da barca Alfred, considerando a geopolítica imperialista no mundo do Oceano Índico e na África oriental, a pressão inglesa contra esse tipo de tráfico, a intensificação da demanda por mão de obra a baixo custo nas regiões tropicais do globo e a agência dos engajados.

No mundo colonial, formas de trabalho sob contrato emergiram com força, misturando-se em uma área cinzenta entre os polos da escravidão e do trabalho livre assalariado. Os sistemas coloniais de trabalho sob contrato em muitos aspectos se assemelhavam à escravidão que supostamente substituíam e eram depositários de ambiguidades responsáveis por tornar a dicotomia trabalho livre/trabalho não-livre analiticamente questionável. Outro aspecto a destacar é a forte relação entre formas de trabalho forçado e os movimentos migratórios, o que fornece pano de fundo para compreensão das migrações de trabalhadores chineses, indianos, africanos, dentre outros, no regime de trabalho sob contrato. A proposta deste artigo é explorar a contradição entre a existência do contrato de engajamento de trabalhadores como instrumento de coerção e a ideia liberal do contrato como um livre acordo entre duas partes, identificando os limites do liberalismo no século XIX quanto à questão do trabalho colonial racializado e seu legado para o século seguinte.

RESUMO O artigo analisa a relação do engajamento de trabalhadores de Moçambique para a Ilha Reunião com a intensificação da demanda por mão de obra a baixo custo nas regiões tropicais do globo, no período da proibição do tráfico de escravos e da abolição da escravidão, em virtude do crescimento do comércio mundial.

AbstractPrevious research on the Bullwhip Effect shows that information visibility—Point‐Of‐Sale (POS) data or supply‐chain partner‐inventory data—can reduce the amplification of orders in a supply chain. This study compiles and analyzes the data from two previous experiments with the beer game (Croson and Donohue, 2003, 2006) to gain insight on the specific mechanisms that decrease order amplification. By structuring the data as a panel and using a fixed‐effects estimation model, we find that additional supply‐chain‐level information (e.g., POS and inventory data) leads subjects to react less aggressively to changes in their own inventory and to pay more attention to the supply line of orders placed. Furthermore, our analysis shows that such effects are more pronounced for upstream subjects. Our findings provide insight into the role that additional supply‐chain information play on subjects' orders in the beer game. © 2021 The Authors. System Dynamics Review published by John Wiley & Sons Ltd on behalf of System Dynamics Society.

AbstractBenefiting from historically favorable conditions (e.g. low costs, fertile land, and abundant water), pistachio producers in Rafsanjan, Iran, have flourished, with pistachio orchards and production growing dramatically since the 1970s. Today, however, the enormous increase in water consumption associated with pistachio production has severely depleted groundwater aquifers, causing widespread water shortages in the region. In this article, we develop a comprehensive system dynamics model, combining the agronomic, economic, hydrologic, and behavioral aspects to analyze the long‐term implications of pistachio production. Our research contributes to the literature of agricultural water management in three significant ways: (i) it provides a validated and quantitative model exploring pistachio farming for a region; (ii) it explicitly captures behavioral decision rules associated with orchard growth and production investment; and (iii) it addresses a natural common‐pool‐resources problem with very long‐time horizons. We consider several policies aimed at addressing the problem (e.g. water transfers, drip irrigation, financial subsidies, income tax, water pricing, and land purchasing). Our results suggest that policies that increase the effectiveness and efficiency of production (e.g. water transfer and drip irrigation respectively), albeit preferred by farmers, lead to better‐before‐worse results, depleting groundwater storage in the long term. Insights from the model can help policymakers have a better understanding of the unintended consequences of their policies. © 2021 The Authors. System Dynamics Review published by John Wiley & Sons Ltd on behalf of System Dynamics Society.

AbstractSmall Island Developing States (SIDS) face tension between economic growth and environmental impact. Tourism fuels growth, but the resulting solid waste and other pollutants threaten the SIDS' natural beauty, quality of life for residents, attractiveness to tourists, and economic success. We assess the tension between tourism‐driven economic growth and environmental degradation from a limits‐to‐growth perspective, developing a generic system dynamics model of the problem using 38 years of data from the Maldives to estimate parameters and Monte‐Carlo methods to assess the sensitivity of results to uncertainty. We contrast development paths for the next three decades under three sets of policies focusing on promoting growth, managing tourism demand–supply balance, and improving waste management. Findings are counterintuitive; policies focused on better waste management alone are self‐defeating, because they increase tourism, growth and waste generation, undermining attractiveness and growth later. Policies that limit tourism demand improve economic and environmental health.© 2018 System Dynamics Society

This paper exposes the development of a written proposal in a 2nd year high school students in a rural school district Santa Terezinha in Itaporã-MS and a part of its results, to promote a reflection on new possibilities for work that contribute to close the gap between school written practices and extracurricular and their socio historical relations. We begin from the assumption that the writing is heterogeneously formed the linguistic facts do not separate the social practices (Corrêa, 2004). The proposal constituted the production of a Virtual Journal on Facebook, developed during the Portuguese classes. The analysis of news production and reporting, plus the comments made on the digital platform, enable linguistically show that there is no rigid boundary between writing practices of focused on writing culture and those of digital culture, as they suppose many educators. Furthermore, show that social networks in school can work as collaborators in a more efficient and meaningful writing instruction for all involved.

Objetiva-se analisar a religião no contexto de secularização e laicidade, considerando o modo como o Direito pode operar em favor da sociedade, pois a efetividade da justiça, que é próprio do Direito, é uma operação emergente para fazer prevalecer no ordenamento jurídico a religião em sua constituição antropológica. Resulta então a constatação de diversas formas da operacionalidade do Direito em tornar plausível a religião.