Understanding Lean Manufacturing According to Axiomatic Design Principles

In this paper, a sequence of implementation steps will be developed through the application of axiomatic design. This sequence will provide a design methodology for lean production which connects manufacturing system design objectives to operation design parameters.Lean Aerospace Initiativ

Axiomatic Design of Manufacturing Systems

This paper introduces the use of axiomatic design in the design of manufacturing systems. The two primary functional requirements of any manufacturing system are developed. These functional requirements are used to analyze the design of four manufacturing systems in terms of system performance. The purpose of this work is to provide a new foundation for describing, determining and rationalizing the design of any new manufacturing system

Spin transport in magnetic multilayers

We study by extensive Monte Carlo simulations the transport of itinerant spins travelling inside a multilayer composed of three ferromagnetic films antiferromagnetically coupled to each other in a sandwich structure. The two exterior films interact with the middle one through non magnetic spacers. The spin model is the Ising one and the in-plane transport is considered. Various interactions are taken into account. We show that the current of the itinerant spins going through this system depends strongly on the magnetic ordering of the multilayer: at temperatures $T$ below (above) the transition temperature $T_c$, a strong (weak) current is observed. This results in a strong jump of the resistance across $T_c$. Moreover, we observe an anomalous variation, namely a peak, of the spin current in the critical region just above $T_c$. We show that this peak is due to the formation of domains in the temperature region between the low-$T$ ordered phase and the true paramagnetic disordered phase. The existence of such domains is known in the theory of critical phenomena. The behavior of the resistance obtained here is compared to a recent experiment. An excellent agreement with our physical interpretation is observed. We also show and discuss effects of various physical parameters entering our model such as interaction range, strength of electric and magnetic fields and magnetic film and non magnetic spacer thicknesses.Comment: 8 pages, 17 figures, submitted to J. Phys.: Cond Matte

Short-time dynamics in the 1D long-range Potts model

We present numerical investigations of the short-time dynamics at criticality in the 1D Potts model with power-law decaying interactions of the form 1/r^{1+sigma}. The scaling properties of the magnetization, autocorrelation function and time correlations of the magnetization are studied. The dynamical critical exponents theta' and z are derived in the cases q=2 and q=3 for several values of the parameter $\sigma$ belonging to the nontrivial critical regime.Comment: 8 pages, 8 figures, minor changes - several typos fixed, one reference change

First-Order Phase Transition in Potts Models with finite-range interactions

We consider the $Q$-state Potts model on $\mathbb Z^d$, $Q\ge 3$, $d\ge 2$, with Kac ferromagnetic interactions and scaling parameter \ga. We prove the existence of a first order phase transition for large but finite potential ranges. More precisely we prove that for \ga small enough there is a value of the temperature at which coexist $Q+1$ Gibbs states. The proof is obtained by a perturbation around mean-field using Pirogov-Sinai theory. The result is valid in particular for $d=2$, Q=3, in contrast with the case of nearest-neighbor interactions for which available results indicate a second order phase transition. Putting both results together provides an example of a system which undergoes a transition from second to first order phase transition by changing only the finite range of the interaction.Comment: Soumis pour publication a Journal of statistical physics - version r\'{e}vis\'{e}

Reexamination of the long-range Potts model: a multicanonical approach

We investigate the critical behavior of the one-dimensional q-state Potts model with long-range (LR) interaction $1/r^{d+\sigma}$, using a multicanonical algorithm. The recursion scheme initially proposed by Berg is improved so as to make it suitable for a large class of LR models with unequally spaced energy levels. The choice of an efficient predictor and a reliable convergence criterion is discussed. We obtain transition temperatures in the first-order regime which are in far better agreement with mean-field predictions than in previous Monte Carlo studies. By relying on the location of spinodal points and resorting to scaling arguments, we determine the threshold value $\sigma_c(q)$ separating the first- and second-order regimes to two-digit precision within the range $3 \leq q \leq 9$. We offer convincing numerical evidence supporting $\sigma_c(q)Comment: 18 pages, 18 figure

Em busca de alternativas ao uso predatório dos recursos florestais na fronteira amazônica.

Neste trabalho, apresentamos a experiência do teste de comercialização da madeira, que levou dois anos entre o lançamento formal da proposta e sua concretização. O obejtivo desse teste era de sistematizar resultados que demonstrassem que a melhor maneira de se buscar a preservação da floresta seria justamente com uma maior valorização de seus produtos atraves do envolvimento direto dos agricultores no processo de transporte e comercialização. Para os pesquisadores do LASAT (Laboratório Sócio-Agronômico do Tocantins) trabalhar a questão da comercialização da madeira era importante não só porque poderia trazer ganhos econômicos aos agricultores, mas porque no futuro poderia envolver muitos destes nas atividades do progrma e dos sindicatos com uma repercusão a nível regional, possibilitando-lhes a participação de fato nas discurssões sobre as políticas referentes à gestão dos recursos naturais. O teste foi realizado na localidade de Josinópolis, Marabá, sitante 250km da sede do Municipio. As condições de realizado foram definidas entre lideranças locais, técnicos e direçãodo sindicato: as espécies comercializadas seriam mógno e cedro, bastante exploradas na Região, retiradas das áreas destinadas a implantação de roças naquele ano agrícola: incluiria 3 ?carradas? de 10m³ de tora: os agricultores seriam responsáveis pela operação de retirada das toras até o cmainhão: o LASAT além de aomcpanhar de perto o trablho dos agrocultores, organizaria o frete e a comercialização. A realização do teste iniciou no final da estação seca, o que dificultou bastante a operação, encarecendo o transporte. Considerando-se todos os custos: preparo da madeira, fretes, deslocamentos de técnicos do LASAT à área e juros (5%), o resultado do teste foi economicamente defitário: receita referente a 37,42m³ de madeira em toras de R$3.624,00 e despesas totais de R$ 4.209,00. Considerando que a situação na qual trabalhamos foi totalmente atípica, em função da época e pouco tempo na sua preparação, o retorno aos agrocultores foi subsidiado: reduziu-se os custos com o frete para o que seria em condições normais, o que proporcionou umretorno aos agricultores de R$ 27,00/m³. O teste nos permintiu concluir que se não for oferecida outras alternativas para a comercialização/beneficiamento da madeira, os pequenos agricultores terão de continuar a se submeter aos quadro atual, em que são quase obrigados a se livrar de suas reservas florestais. Somente uma aliança com a sociedade mais ampla poderia reverter esse padrão e trazer mudanças indispensáveis para s epensar o manejo florestal, pois os agricultores darão mais atenção a mata quando esta trouxer maiores benefícios

Deindustrialization and the Polarization of Household Incomes: The Example of Urban Agglomerations in Germany

The tertiarization, or perhaps more accurately, the deindustrialization of the economy has left deep scars on cities. It is evident not only in the industrial wastelands and empty factory buildings scattered throughout the urban landscape, but also in the income and social structures of cities. Industrialization, collective wage setting and the welfare state led to a stark reduction in income differences over the course of the twentieth century. Conversely, deindustrialization and the shift to tertiary sectors could result in increasing wage differentiation. Moreover, numerous studies on global cities, the dual city, and divided cities have also identified income polarization as a central phenomenon in the development of major cities. Using data from the German Socio-Economic Panel (SOEP), we find an increasing polarization of household income structures since the mid-1990. In agglomerations, this income polarization is even more pronounced than in the more rural regions. The income polarization in Germany is likely to have multiple causes, some of which are directly linked to policies such as the deregulation of the labor market. But extensive deindustrialization is probably also one of the drivers, that has led directly to the weakening of middle income groups