Simulation of the micro-physics of rocks using LSMearth

The particle-based Lattice Solid Model (LSM) was developed to provide a basis to study the physics of rocks and the nonlinear dynamics of earthquakes (MORA and PLACE, 1994; PLACE and MORA, 1999). A new modular and flexible LSM approach has been developed that allows different microphysics to be easily included in or removed from the model. The approach provides a virtual laboratory where numerical experiments can easily be set up and all measurable quantities visualised. The proposed approach provides a means to simulate complex phenomena such as fracturing or localisation processes, and enables the effect of different micro-physics on macroscopic behaviour to be studied. The initial 2-D model is extended to allow three-dimensional simulations to be performed and particles of different sizes to be specified. Numerical bi-axial compression experiments under different confining pressure are used to calibrate the model. By tuning the different microscopic parameters (such as coefficient of friction, microscopic strength and distribution of grain sizes), the macroscopic strength of the material and can be adjusted to be in agreement with laboratory experiments, and the orientation of fractures is consistent with the theoretical value predicted based on Mohr-Coulomb diagram. Simulations indicate that 3-D numerical models have different macroscopic properties than in 2-D and, hence, the model must be recalibrated for 3-D simulations. These numerical experiments illustrate that the new approach is capable of simulating typical rock fracture behaviour. The new model provides a basis to investigate nucleation, rupture and slip pulse propagation in complex fault zones without the previous model limitations of a regular low-level surface geometry and being restricted to two-dimensions.

Simulation of the influence of rate- and state-dependent friction on the macroscopic behavior of complex fault zones with the lattice solid model

In order to understand the earthquake nucleation process, we need to understand the effective frictional behavior of faults with complex geometry and fault gouge zones. One important aspect of this is the interaction between the friction law governing the behavior of the fault on the microscopic level and the resulting macroscopic behavior of the fault zone. Numerical simulations offer a possibility to investigate the behavior of faults on many different scales and thus provide a means to gain insight into fault zone dynamics on scales which are not accessible to laboratory experiments. Numerical experiments have been performed to investigate the influence of the geometric configuration of faults with a rate- and state-dependent friction at the particle contacts on the effective frictional behavior of these faults. The numerical experiments are designed to be similar to laboratory experiments by DIETERICH and KILGORE (1994) in which a slide-hold-slide cycle was performed between two blocks of material and the resulting peak friction was plotted vs. holding time. Simulations with a flat fault without a fault gouge have been performed to verify the implementation. These have shown close agreement with comparable laboratory experiments. The simulations performed with a fault containing fault gouge have demonstrated a strong dependence of the critical slip distance D-c on the roughness of the fault surfaces and are in qualitative agreement with laboratory experiments.

Role of China in the quest to define and control severe acute respiratory syndrome

China holds the key to solving many questions crucial to global control of severe acute respiratory syndrome (SARS). The disease appears to have originated in Guangdong Province, and the causative agent, SARS coronavirus, is likely to have originated from an animal host, perhaps sold in public markets. Epidemiologic findings, integral to defining an animal-human linkage, may be confirmed by laboratory studies; once animal host(s) are confirmed, interventions may be needed to prevent further animal-to-human transmission. Community seroprevalence studies may help determine the basis for the decline in disease incidence in Guangdong Province after February 2002. China will also be able to contribute key data about how the causative agent is transmitted and how it is evolving, as well as identifying pivotal factors influencing disease outcome.

An approach to verifying and debugging simulation models governed by ordinary differential equations: Part 1. Methodology for residual generation

For dynamic simulations to be credible, verification of the computer code must be an integral part of the modelling process. This two-part paper describes a novel approach to verification through program testing and debugging. In Part 1, a methodology is presented for detecting and isolating coding errors using back-to-back testing. Residuals are generated by comparing the output of two independent implementations, in response to identical inputs. The key feature of the methodology is that a specially modified observer is created using one of the implementations, so as to impose an error-dependent structure on these residuals. Each error can be associated with a fixed and known subspace, permitting errors to be isolated to specific equations in the code. It is shown that the geometric properties extend to multiple errors in either one of the two implementations. Copyright (C) 2003 John Wiley Sons, Ltd.

Simulation supplements field studies to determine no-till dryland corn population recommendations for semiarid western Nebraska

In a 2-yr multiple-site field study conducted in western Nebraska during 1999 and 2000, optimum dryland corn (Zea mays L.) population varied from less than 1.7 to more than 5.6 plants m(-2), depending largely on available water resources. The objective of this study was to use a modeling approach to investigate corn population recommendations for a wide range of seasonal variation. A corn growth simulation model (APSIM-maize) was coupled to long-term sequences of historical climatic data from western Nebraska to provide probabilistic estimates of dryland yield for a range of corn populations. Simulated populations ranged from 2 to 5 plants m(-2). Simulations began with one of three levels of available soil water at planting, either 80, 160, or 240 mm in the surface 1.5 m of a loam soil. Gross margins were maximized at 3 plants m(-2) when starting available water was 160 or 240 mm, and the expected probability of a financial loss at this population was reduced from about 10% at 160 mm to 0% at 240 mm. When starting available water was 80 mm, average gross margins were less than $15 ha(-1), and risk of financial loss exceeded 40%. Median yields were greatest when starting available soil water was 240 mm. However, perhaps the greater benefit of additional soil water at planting was reduction in the risk of making a financial loss. Dryland corn growers in western Nebraska are advised to use a population of 3 plants m(-2) as a base recommendation.

Methodologies for calibration and predictive analysis of a watershed model

The use of a fitted parameter watershed model to address water quantity and quality management issues requires that it be calibrated under a wide range of hydrologic conditions. However, rarely does model calibration result in a unique parameter set. Parameter nonuniqueness can lead to predictive nonuniqueness. The extent of model predictive uncertainty should be investigated if management decisions are to be based on model projections. Using models built for four neighboring watersheds in the Neuse River Basin of North Carolina, the application of the automated parameter optimization software PEST in conjunction with the Hydrologic Simulation Program Fortran (HSPF) is demonstrated. Parameter nonuniqueness is illustrated, and a method is presented for calculating many different sets of parameters, all of which acceptably calibrate a watershed model. A regularization methodology is discussed in which models for similar watersheds can be calibrated simultaneously. Using this method, parameter differences between watershed models can be minimized while maintaining fit between model outputs and field observations. In recognition of the fact that parameter nonuniqueness and predictive uncertainty are inherent to the modeling process, PEST's nonlinear predictive analysis functionality is then used to explore the extent of model predictive uncertainty.

Simula????o de reuni??o com dirigente: prepara????o de informa????es e an??lise sobre programa governamental

A simula????o visa preparar gerentes e assessores para organizarem informa????es e diagn??sticos para tomada de decis??o. Apresenta diversos pontos de vista sobre um programa em andamento e estimula debates entre gestores e atores das ??reas envolvidas. A partir da aprecia????o dos pontos de vista desses atores, os participantes dever??o se preparar, em curto espa??o de tempo, para uma reuni??o com o dirigente rec??m-empossado respons??vel pelo programa em quest??o

Portal do software p??blico brasileiro

O Portal do Software P??blico Brasileiro consolida-se como uma iniciativa que conseguiu criar um ambiente comum para compartilhar solu????es de software no setor p??blico, racionalizar a gest??o dos recursos de inform??tica, reaproveitar as solu????es de software existentes para diminuir custos e atividades redundantes, estabelecer parcerias e a????es cooperadas, refor??ar a pol??tica p??blica de estimular o uso de software livre e definir uma forma de licenciamento de software que sustente o compartilhamento de solu????es entre os ??rg??os do setor p??blico de acordo com as prerrogativas legais brasileiras e a Constitui????o Federal. Esta iniciativa trouxe como inova????o o compartilhamento de ???software p??blico???, que oficializou um novo modelo de licenciamento e de gest??o das solu????es desenvolvidas na administra????o p??blica, estabelecendo parceria entre diversos ??rg??os, institui????es, empresas e cidad??os, e hoje conta com mais de 100 mil participantes

Texto para discuss??o 2: a quest??o da estabilidade do servidor p??blico no Brasil: perspectivas de flexibiliza????o

A discuss??o em torno da estabilidade do servidor p??blico emerge a partir de um contexto marcado pela necessidade de transforma????es s??cio-pol??ticas e econ??micas. Essas tranforma????es implicam a reestrutura????o do Estado brasileiro, bem como da administra????o p??blica, tendo em vista a moderniza????o da burocracia, buscando garantir efici??ncia e efic??cia no atendimento do interesse p??blico

Colet??nea planejamento e or??amento governamental: volume 2: temas e quest??es sobre a gest??o da despesa p??blica

O artigo est?? dividido em tr??s partes. Na primeira parte, as caracter??sticas do novo pacote de reformas de gest??o de despesa p??blica s??o visualizadas em termos da situa????o futura ??? ano 2020. Na segunda, s??o discutidos os acontecimentos passados que contribu??ram para a evolu????o do novo pacote. Na terceira, as inova????es do or??amento cumulativo ou da gest??o da despesa s??o discutidas em termos de sua adequa????o para satisfazer as expectativas atuais, bem como a utilidade do pacote no contexto de rubricas cambiantes de despesa p??blica.

Projeto RH NEW: equipe multiprofissional dedicada ao equacionamento das quest??es ligadas a recursos

Este projeto refere-se ao programa de acompanhamento sistematizado dos servidores t??cnico-administrativos da Universidade Federal de Santa Catarina que apresentem ind??cios de uso indevido de drogas, alcoolismo, problemas de relacionamento e outros que influenciam diretamente no comportamento funcional. Para o desenvolvimento deste programa, uma equipe multiprofissional (composta de pedagogo, t??cnico em assuntos educacionais e assistente social) da pr??pria universidade se envolveu com o trabalho. Os resultados s??o significativos principalmente no que se refere ?? inser????o do servidor no ambiente de trabalho, de forma mais produtiva

Crise e reforma do Estado: uma quest??o de cidadania e valoriza????o do servidor

O artigo discute a evolu????o recente da problem??tica da crise do Estado a partir dos tr??s movimentos voltados para a sua supera????o: a busca da efici??ncia, a melhoria da qualidade e o resgate da esfera p??blica como instrumento do exerc??cio da cidadania. Em seguida s??o analisadas as limita????es impostas pelo modelo burocr??tico de administra????o p??blica e apresentadas as experi??ncias recentes de reforma nos EUA, Gr??-Bretanha, Fran??a e Brasil. S??o tamb??m avaliados os impactos do novo modelo de gest??o p??blica nas ??reas de planejamento, controle e desenvolvimento de pessoal. Finalmente o artigo discute o contexto de mudan??a e transforma????o do Estado destacando a necessidade de vincular os conceitos de governabilidade e governan??a aos de cidadania e valoriza????o do servidor p??blico.

Do ICMS ao IVA: a quest??o das transa????es interestaduais no Brasil dos anos 90

O trabalho examina as estat??sticas produzidas pelos Estados acerca das transa????es, submetidas ou n??o ?? incid??ncia do ICMS, realizadas entre eles no ano de 1999. Comparam se os resultados com dados anteriores, relativos ao ano de 1985. O objetivo ?? compreender o significado dessas transa????es para a arrecada????o do imposto, especialmente no momento em que se avizinha, no ??mbito da reforma tribut??ria, a mudan??a no princ??pio de tributa????o, do ???misto???, preponderante atualmente, para o ???de destino???. As estat??sticas produzidas a partir de 1997, em raz??o do processo de discuss??o da reforma tribut??ria, s??o examinadas sobretudo com vistas ?? mudan??a no regime de distribui????o da receita entre as unidades federadas. O trabalho indica, sumariamente, as caracter??sticas relacionadas com as transa????es interestaduais, previstas no debate, para o principal imposto brasileiro ??? o ICMS.