Phase transition in conservative diffusive contact processes

We determine the phase diagrams of conservative diffusive contact processes by means of numerical simulations. These models are versions of the ordinary diffusive single-creation, pair-creation and triplet-creation contact processes in which the particle number is conserved. The transition between the frozen and active states was determined by studying the system in the subcritical regime and the nature of the transition, whether continuous or first order, was determined by looking at the fractal dimension of the critical cluster. For the single-creation model the transition remains continuous for any diffusion rate. For pair- and triplet-creation models, however, the transition becomes first order for high enough diffusion rate. Our results indicate that in the limit of infinite diffusion rate the jump in density equals 2/3 for the pair-creation model and 5/6 for the triplet-creation model

Random-energy model in random fields

The random-energy model is studied in the presence of random fields. The problem is solved exactly both in the microcanonical ensemble, without recourse to the replica method, and in the canonical ensemble using the replica formalism. The phase diagrams for bimodal and Gaussian random fields are investigated in detail. In contrast to the Gaussian case, the bimodal random field may lead to a tricritical point and a first-order transition. An interesting feature of the phase diagram is the possibility of a first-order transition from paramagnetic to mixed phase.Comment: 18 pages, 5 figures (included

Investimento ambiental em indústrias sujas e intensivas em recursos naturais e energia

O crescimento industrial brasileiro, a partir do final dos anos setenta, ocorreu com o aumento da participação de indústrias intensivas em recursos naturais, em detrimento da participação de indústrias intensivas em trabalho e dos setores intensivos em atividades tecnológicas mais complexas. Essas transformações, tornando o setor de bens intermediários dominante na estrutura industrial, implicaram em consideráveis mudanças tanto de ordem espacial quanto na relação com o meio ambiente, o que acarretou no desenvolvimento de uma indústria com maior potencial poluidor. O artigo apresenta os resultados sobre investimentos da indústria brasileira para o controle ambiental, tendo como informação básica os gastos realizados nas aquisições e melhorias de máquinas e equipamentos industriais destinados à redução de resíduos, controle da poluição ou para o atendimento de normas ambientais. As informações foram captadas pela Pesquisa Industrial Anual, realizada pelo IBGE que, relativa aos anos de 1997 e 2002, coletou informações sobre este tipo de investimento. Observa-se que nos anos pesquisados ocorreu um crescimento na ordem de 71% do número de empresas e de 98% no valor investido. O estudo mostra que, em ambos os anos, há uma alta concentração do valor investido pelos setores que mais podem ter contribuído para a degradação ambiental no país.The growth industry Brazilian, within the end of the 1970s, occurs with the expention of the participation of industries in intensive exploitation of natural resources in detriment from participation of industries intensity in work and from the sectors intensity in activities technological more complex. Those transformations becomes the sector of intermediete goods dominant in the structure of the industry, resulting in insignificant gains compered with its order of magnitude in relation to the environment, thus leading to the development of an industry with great potential pollute. The article presents the investments results of Brazilian industry for environmental control, with the basic information about the expenditures incurred, acquisitions and improvements in machinery and industrial equipment interded to reduce waste, pollution control, or for the care of environmental standards. Information was received by the Annual Industrial Research held by the IBGE, on the years 1997 and 2002, collected information about this type of investment. It is observe that in the years studied occurred growth of around 71% of the number of enterprises and 98% in the amount invested. The study shows that in both years, there is a high concentration of the amount invested by most of the sectors that may have contributed to environmental degradation

Event-driven field estimation for wireless sensor networks

This paper introduces and analyzes a field estimation scheme for wireless sensor networks. Our scheme imitates the response of living beings to the surrounding events. The sensors define their periphery of attention based on their own readings. Readings differing from the expected behavior are considered events of interest and trigger the data transmission to the sink. The presented scheme is evaluated with real-site-collected data and the tradeoff between the amount of data sent to the sink and the reconstruction error is analyzed. Results show that signifcant reduction in the data transmission and, as a consequence, in the energy consumption of the network is achievable while keeping low the average reconstruction error.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Event-driven field estimation for wireless sensor networks

This paper introduces and analyzes a field estimation scheme for wireless sensor networks. Our scheme imitates the response of living beings to the surrounding events. The sensors define their periphery of attention based on their own readings. Readings differing from the expected behavior are considered events of interest and trigger the data transmission to the sink. The presented scheme is evaluated with real-site-collected data and the tradeoff between the amount of data sent to the sink and the reconstruction error is analyzed. Results show that signifcant reduction in the data transmission and, as a consequence, in the energy consumption of the network is achievable while keeping low the average reconstruction error.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Investimento ambiental em indústrias sujas e intensivas em recursos naturais e energia

O crescimento industrial brasileiro, a partir do final dos anos setenta, ocorreu com o aumento da participação de indústrias intensivas em recursos naturais, em detrimento da participação de indústrias intensivas em trabalho e dos setores intensivos em atividades tecnológicas mais complexas. Essas transformações, tornando o setor de bens intermediários dominante na estrutura industrial, implicaram em consideráveis mudanças tanto de ordem espacial quanto na relação com o meio ambiente, o que acarretou no desenvolvimento de uma indústria com maior potencial poluidor. O artigo apresenta os resultados sobre investimentos da indústria brasileira para o controle ambiental, tendo como informação básica os gastos realizados nas aquisições e melhorias de máquinas e equipamentos industriais destinados à redução de resíduos, controle da poluição ou para o atendimento de normas ambientais. As informações foram captadas pela Pesquisa Industrial Anual, realizada pelo IBGE que, relativa aos anos de 1997 e 2002, coletou informações sobre este tipo de investimento. Observa-se que nos anos pesquisados ocorreu um crescimento na ordem de 71% do número de empresas e de 98% no valor investido. O estudo mostra que, em ambos os anos, há uma alta concentração do valor investido pelos setores que mais podem ter contribuído para a degradação ambiental no país.Estrutura industrial; indústrias poluidoras; gestão ambiental; investimento ambiental; bens intermediários.

NEEM: network-friendly epidemic multicast

Epidemic, or probabilistic, multicast protocols have emerged as a viable mechanism to circumvent the scalabil- ity problems of reliable multicast protocols. However, most existing epidemic approaches use connectionless transport protocols to exchange messages and rely on the intrinsic robustness of the epidemic dissemination to mask network omissions. Unfortunately, such an approach is not network- friendly, since the epidemic protocol makes no effort to re- duce the load imposed on the network when the system is congested. In this paper, we propose a novel epidemic protocol whose main characteristic is to be network-friendly. This property is achieved by relying on connection-oriented transport connections, such as TCP/IP, to support the com- munication among peers. Since during congestion mes- sages accumulate in the border of the network, the pro- tocol uses an innovative buffer management scheme, that combines different selection techniques to discard messages upon overflow. This technique improves the quality of the information delivered to the application during periods of network congestion. The protocol has been implemented and the benefits of the approach are illustrated using a com- bination of experimental and simulation results