In the past two decades, China has achieved a spectacular success in its economic growth. As a basic input for the production process, the forest resource has been one of the fundamental factors propping up the expansion of China's economy. When China is absorbing imports of timber products in the global market, studies of China's forestry system and its timber market incite greater interest. This paper represents a systematic approach to probe into the comprehensive realities of China's forestry system and its timber market. Econometric methods are applied in analyzing the demand and supply patterns. The empirical analysis is used to forecast the quantity demanded for timber products in China.

Pentachlorophenol (PCP) is a biocide which is widely used for its toxicity to microorganisms. Its major application is in wood preservation, and PCP at abandoned wood preserving sites is a major source of environmental pollution. Although much of the literature documents aerobic treatment for PCP, research indicates that there is great potential for anaerobic dechlorination of these compounds. The objectives of this investigation were to study the acidogenesis phase of the anaerobic biodegradation process; how acidogenesis is affected by PCP toxicity alone and in the presence of zinc; what role acidogenesis plays in the biodegradation of PCP; and how operating parameters, such as organic loading rate (OLR) and solids retention time (SRT) affect the degradation of PCP during acidogenesis. Batch anaerobic toxicity assays (ATAs) were performed to quantify the toxicity threshold for PCP and zinc, and to study the effect of these toxicants on volatile acids production. Continuous reactors (chemostats) were operated at SRTs of 0.25-0.61 day to kinetically exclude methanogenesis from acetate, so that the effects of the toxicants on acidogenesis could be evaluated PCP was found to have a toxicity threshold of 2.7-3.0 mg/L and zinc 23-27 mg/L in batch systems. Acetate utilizers showed the first signs of inhibition in PCP spiked systems, whereas hydrogen utilizers were the first organisms affected in response to a zinc spike. In the continuous systems, PCP in spike concentrations of 7.0 mg/L did not affect the quantity or composition of volatile acids produced in the chemostats. A rise in headspace hydrogen at 30 mg/L zinc indicated that hydrogen utilizers became inhibited in the presence of high zinc concentrations PCP was degraded, with approximately half of the degradation occurring during acidogenesis. GC/MS analysis detected no intermediate chlorophenols in the effluent. The efficiency of degradation varied indirectly with spike concentration and directly with SRT / acase@tulane.edu

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Thesis (Ph. D.)--Columbia University, 2001. / Includes bibliographical references (leaves 203-226).

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Orientador: Marcos David Ferreira / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-22T12:55:03Z (GMT). No. of bitstreams: 1 Braga_CelsodeOliveira_D.pdf: 3406174 bytes, checksum: 113a8ddedc3815bc23a5a33c9e335c89 (MD5) Previous issue date: 2013 / Resumo: O Brasil desponta como grande produtor agrícola, líder em tecnologia de ponta para regiões tropicais e evoluiu da condição de importador para a de grande exportador de alimentos, sendo o quarto produtor mundial de frutas, atrás dos Estados Unidos, da China e da Índia (IBGE, 2010). Para que esta posição se mantenha é fundamental investir em pesquisa e em inovação tecnológica. Este estudo foi desenvolvido em uma unidade beneficiadora de laranja localizada na região de Aguaí, Estado de São Paulo. A laranja foi escolhida devido à sua importância para o agronegócio brasileiro. Um modelo que fornece um quadro avaliativo de uma unidade de beneficiamento (UB) com indicadores de qualidade, de boas práticas agrícolas, de impactos mecânicos e de exigências laborais foi desenvolvido. Desta forma, dois instrumentos inéditos foram criados: o IAQ ou Instrumento para Avaliação de Qualidade e o IABPA, Instrumento para Aplicação das Boas Práticas Agrícolas. A obtenção de indicadores de Qualidade e de BPA permite posicionar a UB em relação às demais UB nacionais e internacionais (ranking) e elaborar o planejamento estratégico para garantir melhorias e competitividade cada vez maior. Para avaliação de Impactos Mecânicos e de Exigências Laborais procedimentos convencionais foram utilizados. A esfera instrumentada foi empregada para avaliação de impactos mecânicos e o instrumento NASA TLX para avaliação das exigências laborais mentais e físicas. Para avaliação de exigências visuais, utilizou-se o instrumento QAV, Questionário de Avaliação Visual. Por intermédio dessas avaliações, podem-se determinar condições adequadas da tecnologia dos equipamentos, da organização do trabalho, do projeto e das condições ambientais do galpão. O conjunto de instrumentos desenvolvidos e utilizados nesta pesquisa constitui um modelo de avaliação e certificação de uma UB que permite um amplo diagnóstico de avaliação e de certificação, com o objetivo de introduzir melhorias e contribuir para garantia da competitividade da UB e da posição do país como grande exportador de alimentos. Este modelo possibilita conhecer o processo produtivo para introdução de melhorias da qualidade e da produtividade, preservando os aspectos ambientais, sociais, de segurança alimentar, de saúde e segurança dos trabalhadores, com sustentabilidade e se aplica a unidades de beneficiamento de outras frutas e hortaliças / Abstract: Brazil is emerging as a major agricultural producer, leader in cutting edge technology for tropical regions and evolving from importer to becoming a major exporter of food, currently being the fourth largest producer of fruit, behind the United States, China and India (IBGE, 2009). In order for this position to be maintained, investment in research and technological innovation is essential. This study was conducted in an orange processing plant in the region of Aguaí, Sao Paulo. The orange was chosen due to its importance for Brazilian agribusiness. A model that provides a framework of an evaluative processing unit (BU) with indicators of quality, good agricultural practices, mechanical impacts and labor requirements was developed. Thus, two new instruments were created: the IAQ or Instrument for Quality Assessment and IABPA, the Instrument for the Application of Good Agricultural Practices. Obtaining Quality indicators and BPA enables positioning this UB in relation to other national and international UB (ranking) and develop strategic planning to ensure improvements and increasing competitiveness. Conventional procedures were used to evaluate impacts of Mechanical and Industrial Requirements. The instrumented sphere was used for the evaluation of mechanical impacts and NASA TLX instrument for the assessment of mental and physical job demands. For evaluation of visual requirements, we used the instrument QAV, Visual Assessment Questionnaire. Through these reviews, one can determine appropriate conditions of technology equipment, work organization, design and environmental conditions of the shed. The set of tools developed and used in this research is a model of evaluation and certification of a UB that allows a broad diagnostic evaluation and certification, in order to make improvements and contribute to ensuring the competitiveness of UB and the country's position as major food exporter. This model enables the understanding and improving of the production process for improvements in quality and productivity, preserving the environmental, social, food security, health and safety aspects of workers, with sustainability and can also be applied to processing units of other fruits and vegetables / Doutorado / Planejamento e Desenvolvimento Rural Sustentável / Doutor em Engenharia Agrícola

In this dissertation I develop a Marxian class analysis of corn-producing family farms in the Midwestern United States during the early twentieth century. I theorize the family farm as a complex hybrid of mostly feudal and ancient class structures that has survived through a contradictory combination of strategies that includes the feudal exploitation of farm family members, the cannibalization of neighboring ancient farmers in a vicious hunt for superprofits, and the intervention of state welfare programs. The class-based definition of the family farm yields unique insights into three broad aspects of U.S. agricultural history. First, my analysis highlights the crucial, yet under-recognized role of farm women and children's unpaid labor in subsidizing the family farm. Second I offer a new, class-based perspective on the roots of the twentieth century "miracle of productivity" in U.S. agriculture, the rise of the agribusiness giants that depended on the perpetual, technology-induced crisis of that agriculture, and the implications of government farm programs. Third, this dissertation demonstrates how the unique set of contradictions and circumstances facing family farmers during the early twentieth century, including class exploitation, were connected to concern for their ability to serve the needs of U.S. industrial capitalist development. The argument presented here highlights the significant costs associated with the intensification of exploitation in the transition to industrial agriculture in the U.S. The family farm is implicated in this social theft. Ironically, the same family farm is often held up as the bedrock of American life. Its exalted status as an example of democracy, independence, self-sufficiency, and morality is enabled among other things by the absence of class awareness in U.S. society. When viewed through the lens of class, the hallowed family farm becomes example of one of the most exploitative institutions in the U.S. economy. The myth of its superiority takes on a new significance as one of the important non-economic processes helping to overdetermine the family farm's long survival, while participating in foreclosing truly radical transformations of these institutions to non-exploitative alternatives.