895 resultados para Paper type
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Mode of access: Internet.
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Laser desorption ionisation mass spectrometry (LDI-MS) has demonstrated to be an excellent analytical method for the forensic analysis of inks on a questioned document. The ink can be analysed directly on its substrate (paper) and hence offers a fast method of analysis as sample preparation is kept to a minimum and more importantly, damage to the document is minimised. LDI-MS has also previously been reported to provide a high power of discrimination in the statistical comparison of ink samples and has the potential to be introduced as part of routine ink analysis. This paper looks into the methodology further and evaluates statistically the reproducibility and the influence of paper on black gel pen ink LDI-MS spectra; by comparing spectra of three different black gel pen inks on three different paper substrates. Although generally minimal, the influences of sample homogeneity and paper type were found to be sample dependent. This should be taken into account to avoid the risk of false differentiation of black gel pen ink samples. Other statistical approaches such as principal component analysis (PCA) proved to be a good alternative to correlation coefficients for the comparison of whole mass spectra.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This article describes a real-world production planning and scheduling problem occurring at an integrated pulp and paper mill (P&P) which manufactures paper for cardboard out of produced pulp. During the cooking of wood chips in the digester, two by-products are produced: the pulp itself (virgin fibers) and the waste stream known as black liquor. The former is then mixed with recycled fibers and processed in a paper machine. Here, due to significant sequence-dependent setups in paper type changeovers, sizing and sequencing of lots have to be made simultaneously in order to efficiently use capacity. The latter is converted into electrical energy using a set of evaporators, recovery boilers and counter-pressure turbines. The planning challenge is then to synchronize the material flow as it moves through the pulp and paper mills, and energy plant, maximizing customer demand (as backlogging is allowed), and minimizing operation costs. Due to the intensive capital feature of P&P, the output of the digester must be maximized. As the production bottleneck is not fixed, to tackle this problem we propose a new model that integrates the critical production units associated to the pulp and paper mills, and energy plant for the first time. Simple stochastic mixed integer programming based local search heuristics are developed to obtain good feasible solutions for the problem. The benefits of integrating the three stages are discussed. The proposed approaches are tested on real-world data. Our work may help P&P companies to increase their competitiveness and reactiveness in dealing with demand pattern oscillations. (C) 2012 Elsevier Ltd. All rights reserved.
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In previous papers, the type-I intermittent phenomenon with continuous reinjection probability density (RPD) has been extensively studied. However, in this paper type-I intermittency considering discontinuous RPD function in one-dimensional maps is analyzed. To carry out the present study the analytic approximation presented by del Río and Elaskar (Int. J. Bifurc. Chaos 20:1185-1191, 2010) and Elaskar et al. (Physica A. 390:2759-2768, 2011) is extended to consider discontinuous RPD functions. The results of this analysis show that the characteristic relation only depends on the position of the lower bound of reinjection (LBR), therefore for the LBR below the tangent point the relation {Mathematical expression}, where {Mathematical expression} is the control parameter, remains robust regardless the form of the RPD, although the average of the laminar phases {Mathematical expression} can change. Finally, the study of discontinuous RPD for type-I intermittency which occurs in a three-wave truncation model for the derivative nonlinear Schrodinger equation is presented. In all tests the theoretical results properly verify the numerical data
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Na Fábrica de Papel da Ponte Redonda fabricam-se sacos de papel multi-folhas e papel reciclado do tipo Kraft. Tendo em consideração a primeira actividade, é de grande interesse optimizar o processo de fabrico de papel com vista a incorporara a máxima taxa de papel produzido internamente nas diferentes camadas dos sacos de papel. Os papéis de maior interesse são os do tipo Fluting e Liners, tendo sido produzidos em 2010 um total de 4,9 mil toneladas, ou seja 90% de todo o papel fabricado em 2010, correspondendo a a 4 mil toneladas de papéis do tipo Liners e 0,9 mil toneladas para os papéis do tipo Fluting. Nos papéis do tipo Liners incluem-se os papéis do tipo Test-Liner e Kraft-Liner, representando em termos produtivos valores idênticos. No âmbito deste trabalho, em que se pretendeu controlar as águas do processo e optimizar a produção de papel, foram introduzidos uma unidade de flutuação e um sistema que permitisse regular a consistência da suspensão fibrosa à entrada da máquina do papel, e foram ainda estudadas as possibilidades de adição de produtos químicos para melhorar as características da pasta assim como um tratamento microbiológico mais eficaz para todo o processo. Para se avaliar se as medidas implementadas teriam um impacto positivo na qualidade desses dois tipos de papéis, desenvolveu-se o trabalho em duas fases: a primeira envolve a introdução de um sistema de flutuação e de um sistema de controlo de consistência da pasta, assim como a selecção de produtos químicos a adicionar ao processo. A segunda fase consistiu na avaliação do efeito destas medidas nas características do papel fabricado. Para o efeito foram escolhidos dois tipos de papel e de diferentes gramagens, nomeadamente Test-Liner de 80 g/m2 e Fluting de 110 g/m2. Introduziu-se um flutuador com o objectivo de tratar parte das águas do processo de fabrico com vista a serem reutilizadas em determinadas aplicações possíveis para a qualidade da água obtida (lavagens e água do processo), de modo a conseguir-se uma poupança de água, assim como aproveitar-se as lamas resultantes, ricas em fibra de celulose, para utilizá-las como matéria-prima. Foi introduzido um regulador de consistência no processo da Ponte Redonda com o objectivo de alimentar de uma forma constante a consistência da pasta à entrada da máquina do papel proporcionando uma melhor formação da folha, devido à ligação entre fibras, na direcção máquina e direcção transversal. Esse sistema inovador é um Regulador de Consistência que vem proporcionar à máquina do papel uma alimentação em fibra mais constante. O fabrico de papel apenas a partir de fibras de celulose não permitirá obter um papel com as características desejadas para a sua utilização. Para corrigir estas deficiências, são adicionados produtos químicos para atribuir ou melhorar as propriedades dos papéis. Desta forma considerou-se interessante introduzir no processo um agente de retenção numa fase posterior à preparação da pasta e antes da chegada à máquina de papel, de forma a melhorar as características da suspensão fibrosa. Assim foi implementado um sistema cuja eficácia foi avaliada. Concluiu-se que com a sua implementação a máquina de papel apresentou melhores resultados na drenagem e na turbidez da água removida, significando uma água com menor teor de matéria suspensa e dissolvida, devido à melhor agregação das fibras dispersas na suspensão fibrosa, levando a um aumento da drenagem e consequentemente melhor eficiência das prensas e secaria. Foi também elaborado um estudo para introdução de um sistema de tratamento microbiológico em todo o processo de fabrico de papel, devido à existência de microorganismos prejudiciais ao seu fabrico. Concluiu-se que a água clarificada proveniente do flutuador apresentou qualidade aceitável para os objectivos pretendidos. No entanto, considerando a eficiência de 26,5% na remoção de sólidos suspensos será necessário mais algum tempo de utilização da água clarificada, cerca de um ano, para avaliar se esta terá algum efeito prejudicial nos equipamentos. Verificou-se que devido à existência de microrganismos em todo o processo de fabrico de papel será necessário efectuar lavagens aos tinões, tanques e circuitos com alguma regularidade, aproveitando-se as paragens do processo assim como implementar um sistema de tratamento microbiológico mais eficaz. Em resultado das medidas implementadas concluiu-se que os papéis produzidos apresentaram melhorias, tendo-se obtido melhores resultados em todos os ensaios de resistência. No papel do tipo Test-Liner destacam-se os bons resultados nos ensaios de superfície, Cobb60 e rebentamento. No caso do parâmetro do Cobb60, foi um resultado surpreendente visto que por norma este tipo de papéis reciclados não suportam este ensaio. Concluiu-se também que as medidas implementadas proporcionaram uma melhor agregação e ligação entre fibras, e melhor formação da folha na máquina do papel proporcionando aos papéis propriedades físico-mecânicas mais interessantes.
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Purpose: The purpose of this paper is to analyse the impact of business exits on future dimensions of entrepreneurial activity at the macroeconomic level. Design/methodology/approach: This research uses the Global Entrepreneurship Monitor (GEM) data for 41 countries and the Generalized Method of Moments (GMM) to carry out the analysis. The paper differentiates the effect of the two components of total entrepreneurial activity, and the two motivations for it – opportunity and necessity entrepreneurship. Findings: The results presented here show a positive and significant effect of the coefficient associated with exits in all models. This means that the levels of entrepreneurial activity exceed business exits. The robustness of the models are tested, including other variables such as the fear of failure, the Gross Domestic Product, role models, entrepreneurial skills and the unemployment variables. The main hypothesis which stated that at national level business exits imply greater rates of opportunity-driven entrepreneurship is corroborated. Originality/value: One would expect that unemployment rates would imply higher levels of necessity entrepreneurship. However, results show that unemployment rates do in fact favour opportunity entrepreneurship levels. This could be due to those government policies that are aimed at promoting entrepreneurship through the capitalization of unemployment to be totally invested in a new start-up. To the best of our knowledge, this is the first panel data study to link previous exit rates to future dimensions of entrepreneurial activity. Keywords: Entrepreneurship, business exits, social values, industrial organization Paper type: Research paper
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Abstract Purpose- There is a lack of studies on tourism demand forecasting that use non-linear models. The aim of this paper is to introduce consumer expectations in time-series models in order to analyse their usefulness to forecast tourism demand. Design/methodology/approach- The paper focuses on forecasting tourism demand in Catalonia for the four main visitor markets (France, the UK, Germany and Italy) combining qualitative information with quantitative models: autoregressive (AR), autoregressive integrated moving average (ARIMA), self-exciting threshold autoregressions (SETAR) and Markov switching regime (MKTAR) models. The forecasting performance of the different models is evaluated for different time horizons (one, two, three, six and 12 months). Findings- Although some differences are found between the results obtained for the different countries, when comparing the forecasting accuracy of the different techniques, ARIMA and Markov switching regime models outperform the rest of the models. In all cases, forecasts of arrivals show lower root mean square errors (RMSE) than forecasts of overnight stays. It is found that models with consumer expectations do not outperform benchmark models. These results are extensive to all time horizons analysed. Research limitations/implications- This study encourages the use of qualitative information and more advanced econometric techniques in order to improve tourism demand forecasting. Originality/value- This is the first study on tourism demand focusing specifically on Catalonia. To date, there have been no studies on tourism demand forecasting that use non-linear models such as self-exciting threshold autoregressions (SETAR) and Markov switching regime (MKTAR) models. This paper fills this gap and analyses forecasting performance at a regional level. Keywords Tourism, Forecasting, Consumers, Spain, Demand management Paper type Research paper
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Purpose – This study aims to provide a review of brownfield policy and the emerging sustainable development agenda in the UK, and to examine the development industry’s (both commercial and residential) role and attitudes towards brownfield regeneration and contaminated land. Design/methodology/approach – The paper analyses results from a two-stage survey of commercial and residential developers carried out in mid-2004, underpinned by structured interviews with 11 developers. Findings – The results suggest that housebuilding on brownfield is no longer the preserve of specialists, and is now widespread throughout the industry in the UK. The redevelopment of contaminated sites for residential use could be threatened by the impact of the EU Landfill Directive. The findings also suggest that developers are not averse to developing on contaminated sites, although post-remediation stigma remains an issue. The market for warranties and insurance continues to evolve. Research limitations/implications – The survey is based on a sample which represents nearly 30 per cent of UK volume housebuilding. Although the response in the smaller developer groups was relatively under-represented, non-response bias was not found to be a significant issue. More research is needed to assess the way in which developers approach brownfield regeneration at a local level. Practical implications – The research suggests that clearer Government guidance in the UK is needed on how to integrate concepts of sustainability in brownfield development and that EU policy, which has been introduced for laudable aims, is creating tensions within the development industry. There may be an emphasis towards greenfield development in the future, as the implications of the Barker review are felt. Originality/value – This is a national survey of developers’ attitudes towards brownfield development in the UK, following the Barker Review, and highlights key issues in UK and EU policy layers. Keywords Brownfield sites, Contamination Paper type Research paper
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Purpose – This paper aims to review traditional corporate governance and accountability research, to suggest opportunities for future research in this field. Design/methodology/approach – The first part adopts an analytical frame of reference based on theory, accountability mechanisms, methodology, business sector/context, globalisation and time horizon. The second part of the paper locates the seven papers in the special issue in a framework of analysis showing how each one contributes to the field. The paper presents a frame of reference which may be used as a “roadmap” for researchers to navigate their way through the prior literature and to position their work on the frontiers of corporate governance research. The paper is primarily discursive and conceptual. Findings – The paper encourages broader approaches to corporate governance and accountability research beyond the traditional and primarily quantitative approaches of prior research. Broader theoretical perspectives, methodological approaches, accountability mechanism, sectors/contexts, globalisation, and time horizons are identified. Research limitations/implications – Greater use of qualitative research methods are suggested, which present challenges particularly of access to the “black box” of corporate boardrooms. Originality/value – Drawing on the analytical framework, and the papers in the special issue, the paper identifies opportunities for further research of accountability and corporate governance. Keywords Corporate governance, Management accountability, Research Paper type General review
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Purpose – The purpose of this paper is to describe the tools and strategies that were employed by C/W MARS to successfully develop and implement the Digital Treasures digital repository. Design/methodology/approach – This paper outlines the planning and subsequent technical issues that arise when implementing a digitization project on the scale of the large, multi-type, automated library network. Workflow solutions addressed include synchronous online metadata record submissions from multiple library sources and the delivery of collection-level use statistics to participating library administrators. The importance of standards-based descriptive metadata and the role of project collaboration are also discussed. Findings – From the time of its initial planning, the Digital Treasures repository was fully implemented in six months. The discernable and statistically quantified online discovery and access of actual digital objects greatly assisted libraries unsure of their own staffing costs/benefits to join the repository. Originality/value – This case study may serve as a possible example of initial planning, workflow and final implementation strategies for new repositories in both the general and library consortium environment. Keywords – Digital repositories, Library networks, Data management. Paper type – Case study
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Purpose – The aim of this chapter is to shed some light on the antecedents of organizational commitment, the mediating role of job engagement and job satisfaction as determinants of organizational commitment within the public sector environment, and the effects that national cultural values may have on these relationships. Approach – This paper presents a review of the works that, from both theoretical and empirical points of view, explore the affecting factors of public employees’ organizational commitment in an international setting. Findings – A comprehensive model has been developed, detailing the expectations on the influence that these factors might have on public employees’ level of commitment, either as mediators or moderators. Research limitations/implications – The main limitation is the paper’s theoretical nature; the subsequent implication is a future empirical research that may prove or disprove these theoretical findings. In addition, there are some other possible mediating factors and antecedents which may be of interest for future researchers. Originality/value – This comprehensive review of the extant literature may provide academics and public managers with a deeper comprehension of how organizational commitment might be achieved, and why some practices may or may not be transferrable from one country to another.
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The collection of dried blood spots (DBS) on filter paper provides a powerful approach for the development of large-scale, population-based screening programs. DBS methods are particularly valuable in developing countries and isolated rural regions where resources are limited. Large numbers of field specimens can be economically collected and shipped to centralized reference laboratories for genetic and (or) serological analysis. Alternatively, the dried blood can be stored and used as an archival resource to rapidly establish the frequency and distribution of newly recognized mutations, confirm patient identity or track the origins and emergence of newly identified pathogens. In this report, we describe how PCR-based technologies are beginning to interface with international screening programmes for the diagnosis and genetic characterization of human immunodeficiency virus type 1 (HIV-1). In particular, we review recent progress using DBS specimens to resolve the HIV-1 infection status of neonates, monitor the genetic evolution of HIV-1 during early infancy and establish a sentinel surveillance system for the systematic monitoring of HIV-1 genetic variation in Asia.