TBM pressure models: observations, theory and practice

Mechanized tunnelling in soft ground has evolved significantly over the last 20 years. However, the interaction between the tunnel boring machine (TBM) and the ground is often understood through idealized concepts, focused mostly on the machine actions in detriment of the reactions from the ground. These concepts cannot be used to explain several mechanisms that have been observed during the construction of mechanized tunnels. Therefore, this paper presents the path from field observations to the theoretical developments to model the TBM-ground interaction more realistically. Some ideas on how these developments can be applied into practice are presented. Finally, a discussion is proposed about how an effective collaboration between academia and industry can alleviate the current concentration of knowledge in the state of practice

Using computer-generated design aids to facilitate alternative concept embodiments

The objective of this study was to investigate whether the use of computer-generated aids facilitates a greater variety of concept embodiments compared to the classical approach. A total of 60 participants were enrolled in the Design Methodology course. They were divided into a control group using the classical approach and an experimental group in which computer-generated aids were employed. The embodiments produced by the participants from both groups were assessed for variety, independently by two experts having both academic and industrial experience in the field of product development. The experts were not informed about the groups or any of the study details. Analysis of the results of this experiment indicates that computer-generated aids play a supportive role in concept embodiment

The Industrial Revolution as the Escape from the Malthusian Trap

industrial revolution; Malthusian trap

Space exploration: The interstellar goal and Titan demonstration

Automated interstellar space exploration is reviewed. The Titan demonstration mission is discussed. Remote sensing and automated modeling are considered. Nuclear electric propulsion, main orbiting spacecraft, lander/rover, subsatellites, atmospheric probes, powered air vehicles, and a surface science network comprise mission component concepts. Machine, intelligence in space exploration is discussed

Transaction costs and their implications to formation of contractual arrangements: aspects of machinery contracting by family farmers in the centro-serra region of Rio Grande do Sul.

A mecanização da produção agrícola desempenha um importante e crescente papel no curso do desenvolvimento agrícola e rural. A mecanização oferece diversas melhorias potenciais nos sistemas de produção tais como o incremento da produtividade da terra e do trabalho, a redução dos riscos, e aumento da qualidade e segurança alimentar de produtos de origem animal e vegetal. Entretanto, os investimentos necessários para compra de máquinas, especialmente para pequenos produtores, podem não ser a opção de menor custo em comparação com a obtenção de serviços de mecanização por meio de diferentes arranjos contratuais. Para .. escolher a melhor forma de contratar serviços de mecanização é necessário avaliar tanto os . custos convencionais das máquinas quanto os custos de transação, O principal objetivo desta pesquisa foi estimar a importância dos custos de transação na tomada de decisão sobre a seleção de arranjos contratuais alternativos para contratação de serviços de mecanização. Nossa hipótese era de. que os custos de transação podem ser maiores que os custos das máquinas, podendo, com isso, ser de cruclal Importância na seleção do tipo de arranjo contratual para contratar serviços de mecanização. Os dados empíricos de custos de máquinas e de transação foram coletados junto a agricultores familiares da Região Centro-Serra (RS), os quais contrataram serviços de colheita para milho de diferentes fornecedores formais e informais. Os resultados mostraram que os custos de transação podem ser mais elevados que os custos das máquinas e, com isso, influenciam de forma significativa a preferência agricultores familiares por determinado tipo de arranjo contratual para obtenção de serviços de mecanização. ABSTRACT - The mechanization of agricultural production plays an important and in course of time increasing role in the course of agricultural and rural development. Mechanization offers several potential improvements to farming systems such as increased land and labor productivity, reduction of risks, and increase of quality and food safety of animal and plant products. However, investments in own machinery, in particular for small holders, may not be the least-cost option in comparison with outsourcing the required machinery services through different contractual relationships. To choose the optimal contract for obtaining machinery services, it is necessary to evaluate conventional machinery costs as well as transaction costs. The main objective of this research was to assess the role of transaction costs in the choice among alternative contractual arrangements for provision of machinery services. Our hypothesis was that transaction costs can be higher than machinery costs, and therefore, they can play a leading role in the choice of contractual arrangements for provision of machinery services. The empirical data on conventional machinery and transaction costs were collected from farms in Southern Brazil that procure services for maize harvest through various informal and formal contractual forms. We found that transaction costs can be higher than conventional machinery costs, and therefore, influence the choice of contractual arrangement