Single Particle and Packed Bed Combustion in Modern Gasifier Stoves—Density Effects

This article is concerned with a study of an unusual effect due to density of biomass pellets in modern stoves based on close-coupled gasification-combustion process. The two processes, namely, flaming with volatiles and glowing of the char show different effects. The mass flux of the fuel bears a constant ratio with the air flow rate of gasification during the flaming process and is independent of particle density; char glowing process shows a distinct effect of density. The bed temperatures also have similar features: during flaming, they are identical, but distinct in the char burn (gasification) regime. For the cases, wood char and pellet char, the densities are 350, 990 kg/m(3), and the burn rates are 2.5 and 3.5 g/min with the bed temperatures being 1380 and 1502 K, respectively. A number of experiments on practical stoves showed wood char combustion rates of 2.5 +/- 0.5 g/min and pellet char burn rates of 3.5 +/- 0.5 g/min. In pursuit of the resolution of the differences, experimental data on single particle combustion for forced convection and ambient temperatures effects have been obtained. Single particle char combustion rate with air show a near-d(2) law and surface and core temperatures are identical for both wood and pellet char. A model based on diffusion controlled heat release-radiation-convection balance is set up. Explanation of the observed results needs to include the ash build-up over the char. This model is then used to explain observed behavior in the packed bed; the different packing densities of the biomass chars leading to different heat release rates per unit bed volume are deduced as the cause of the differences in burn rate and bed temperatures.

Optimal control for the rolling pullout maneuver of a modern fighter aircraft

Optimal control laws are obtained for the elevator and the ailerons for a modern fighter aircraft in a rolling pullout maneuver. The problem is solved for three flight conditions using the conjugate gradient method.

Modern energy access to all in rural India: An integrated implementation strategy

Expanding energy access to the rural population of India presents a critical challenge for its government. The presence of 364 million people without access to electricity and 726 million who rely on biomass for cooking indicate both the failure of past policies and programs, and the need for a radical redesign of the current system. We propose an integrated implementation framework with recommendations for adopting business principles with innovative institutional, regulatory, financing and delivery mechanisms. The framework entails establishment of rural energy access authorities and energy access funds, both at the national and regional levels, to be empowered with enabling regulatory policies, capital resources and the support of multi-stakeholder partnership. These institutions are expected to design, lead, manage and monitor the rural energy interventions. At the other end, trained entrepreneurs would be expected to establish bioenergy-based micro-enterprises that will produce and distribute energy carriers to rural households at an affordable cost. The ESCOs will function as intermediaries between these enterprises and the international carbon market both in aggregating carbon credits and in trading them under CDM. If implemented, such a program could address the challenges of rural energy empowerment by creating access to modern energy carriers and climate change mitigation. (C) 2011 Elsevier Ltd. All rights reserved.

Integrating biodiversity and conservation with modern agricultural landscapes

To achieve food security and meet the demands of the ever-growing human populations, farming systems have assumed unsustainable practices to produce more from a finite land area. This has been cause for concern mainly due to the often-irreversible damage done to the otherwise productive agricultural landscapes. Agro-ecology is proclaimed to be deteriorating due to eroding integrity of connected ecological mosaics and vulnerability to climate change. This has contributed to declining species diversity, loss of buffer vegetation, fragmentation of habitats, and loss of natural pollinators or predators, which eventually leads to decline in ecosystem services. Currently, a hierarchy of conservation initiatives is being considered to restore ecological integrity of agricultural landscapes. However, the challenge of identifying a suitable conservation strategy is a daunting task in view of socio-ecological factors that may constrain the choice of available strategies. One way to mitigate this situation and integrate biodiversity with agricultural landscapes is to implement offset mechanisms, which are compensatory and balancing approaches to restore the ecological health and function of an ecosystem. This needs to be tailored to the history of location specific agricultural practices, and the social, ecological and environmental conditions. The offset mechanisms can complement other initiatives through which farmers are insured against landscape-level risks such as droughts, fire and floods. For countries in the developing world with significant biodiversity and extensive agriculture, we should promote a comprehensive model of sustainable agricultural landscapes and ecosystem services, replicable at landscape to regional scales. Arguably, the model can be a potential option to sustain the integrity of biodiversity mosaic in agricultural landscapes.

Impacts of modern transitions on thermal comfort in vernacular dwellings in warm-humid climate of Sugganahalli (India)

Sugganahalli, a rural vernacular community in a warm-humid region in South India, is under transition towards adopting modern construction practices. Vernacular local building elements like rubble walls and mud roofs are given way to burnt brick walls and reinforced cement concrete (RCC)/tin roofs. Over 60% of Indian population is rural, and implications of such transitions on thermal comfort and energy in buildings are crucial to understand. Vernacular architecture evolves adopting local resources in response to the local climate adopting passive solar designs. This paper investigates the effectiveness of passive solar elements on the indoor thermal comfort by adopting modern climate-responsive design strategies. Dynamic simulation models validated by measured data have also been adopted to determine the impact of the transition from vernacular to modern material-configurations. Age-old traditional design considerations were found to concur with modern understanding into bio-climatic response and climate-responsiveness. Modern transitions were found to increase the average indoor temperatures in excess of 7 degrees C. Such transformations tend to shift the indoor conditions to a psychrometric zone that is likely to require active air-conditioning. Also, the surveyed thermal sensation votes were found to lie outside the extended thermal comfort boundary for hot developing countries provided by Givoni in the bio-climatic chart.

Graph Modification Problems: A Modern Perspective

We give an overview of recent results and techniques in parameterized algorithms for graph modification problems.

De la lírica medieval a la moderna : tradicionalidad e individualidad en la poesía española

Integran este número de la revista ponencias presentadas en Studia Hispanica Medievalia VIII : Actas de las X Jornadas Internacionales de Literatura Española Medieval, 2011, y de Homenaje al Quinto Centenario del Cancionero General de Hernando del Castillo.

Hannah Arendt y Walter Benjamin : masa, multitud, populacho

Resumen: Hannah Arendt y Walter Benjamin examinan los fenómenos asociativos de masa, multitud y populacho. Ambos sustraen tales grupos del ámbito político y los sitúan en el ámbito social. En Los orígenes del totalitarismo, Arendt indaga la noción de populacho o mob en el contexto del fenómeno imperialista. Asocia el carácter del populacho con el de la clase burguesa y posiciona ambos grupos en la emergencia de los nacionalismos tribales, ambos antecesores del totalitarismo. La masa es consustancial con los regímenes totalitarios. La apatía cívica, el cinismo y el derrumbe de las costumbres burguesas no alcanzan para explicar el fenómeno totalitario. El hombre masa ha perdido incluso el interés por sí mismo y el gusto por las asociaciones no partidarias. Walter Benjamin reflexiona literariamente los fenómenos de la bohème y de la multitud (crowd), a través de la poesía de Baudelaire y los relatos de Poe. El primer grupo incluye los conspiradores profesionales, cuyo aislamiento y resentimiento los emparenta con los miembros del mob. La falta de pertenencia y la ausencia de vínculos los conduce al activismo, sin un programa de acción. En el contexto de su reflexión sobre el fenómeno de la multitud, Benjamin indaga el impacto de las condiciones de vida moderna en las conductas automatizadas de los individuos. Los comportamientos reflejos, las respuestas automatizadas y los clichés, son las notas que también Arendt encuentra en el hombre “normal” y diluido en la masa, como lo evidenció la conducta de Eichmann durante el proceso en Jerusalén

Profit and Cost in "Modern" Post-Marxian Profit Theory: A Case Study from Varian's "Intermediate Microeconomics"

In this paper, I examine the treatment of competitive profit of professor Varian in his textbook on Microeconomics, as a representative of the “modern” post-Marxian view on competitive profit. I show how, on the one hand, Varian defines profit as the surplus of revenues over cost and, thus, as a part of the value of commodities that is not any cost. On the other hand, however, Varian defines profit as a cost, namely, as the opportunity cost of capital, so that, in competitive conditions, the profit or income of capital is determined by the opportunity cost of capital. I argue that this second definition contradicts the first and that it is based on an incoherent conception of opportunity cost.

Guided pollards in the Basque Country (Spain) during the Early Modern Ages

Publicado en: "End of Tradition?.Part 1 : History of Commons and Commons Management (Cultural Severance and Commons Past)", edited by Ian D. Rotherham, Mauro Agnoletti and Christine Handley