A new approach for fast potential evaluation in N-body problems

Fast algorithms for potential evaluation in N-body problems often tend to be extremely abstract and complex. This thesis presents a simple, hierarchical approach to solving the potential evaluation problem in O(n) time. The approach is developed in the field of electrostatics and can be extended to N-body problems in general. Herein, the potential vector is expressed as a product of the potential matrix and the charge vector. The potential matrix itself is a product of component matrices. The potential function satisfies the Laplace equation and is hence expressed as a linear combination of spherical harmonics, which form the general solutions of the Laplace equation. The orthogonality of the spherical harmonics is exploited to reduce execution time. The duality of the various lists in the algorithm is used to reduce storage and computational complexity. A smart tree-construction strategy leads to efficient parallelism at computation intensive stages of the algorithm. The computational complexity of the algorithm is better than that of the Fast Multipole Algorithm, which is one of the fastest contemporary algorithms to solve the potential evaluation problem. Experimental results show that accuracy of the algorithm is comparable to that of the Fast Multipole Algorithm. However, this approach uses some implementation principles from the Fast Multipole Algorithm. Parallel efficiency and scalability of the algorithms are studied by the experiments on IBM p690 multiprocessors

A new approach for fast potential evaluation in N-body problems

Fast algorithms for potential evaluation in N-body problems often tend to be extremely abstract and complex. This thesis presents a simple, hierarchical approach to solving the potential evaluation problem in O(n) time. The approach is developed in the field of electrostatics and can be extended to N-body problems in general. Herein, the potential vector is expressed as a product of the potential matrix and the charge vector. The potential matrix itself is a product of component matrices. The potential function satisfies the Laplace equation and is hence expressed as a linear combination of spherical harmonics, which form the general solutions of the Laplace equation. The orthogonality of the spherical harmonics is exploited to reduce execution time. The duality of the various lists in the algorithm is used to reduce storage and computational complexity. A smart tree-construction strategy leads to efficient parallelism at computation intensive stages of the algorithm. The computational complexity of the algorithm is better than that of the Fast Multipole Algorithm, which is one of the fastest contemporary algorithms to solve the potential evaluation problem. Experimental results show that accuracy of the algorithm is comparable to that of the Fast Multipole Algorithm. However, this approach uses some implementation principles from the Fast Multipole Algorithm. Parallel efficiency and scalability of the algorithms are studied by the experiments on IBM p690 multiprocessors

Strategies and Programs for Improved Nutrient Use Efficiency, Doubling Farmer’s Income, and Sustainable Agriculture: Indian Context

Since the Green Revolution era, the farming sector exploited the soils for food, fiber, fodder, etc., with high input responsive varieties that excavated vast amounts of chemical fertilizers. The burgeoning population of the country calls for a commensurate increase in food production to satisfy the demands of its inhabitants. Further, due to innovative mechanization in agriculture, specialization, and government policy programs, the productivity of food has soared. Subsequently, it ensued greater productions and minimized food prizes. Regrettably, intensive agricultural operations degraded the soil quality and now reached such a stage where without external inputs, growers unable to achieve their targeted yields. India has lost 68% innate productive capacity of agricultural soils. This plunder of land’s quality continues unabated, further resulting in low nutrient use efficiency and insufficient yields of agroecosystems. Therefore, this is high time to realize the dreadful impacts of intensive crop production on the natural ecosystem. Irrefutably, both soil and its nutrients are the wondrous gifts of nature to humankind; utilizing them sustainably is imperative. The present chapter highlights the impacts of non-judicious nutrient management on soil productivity, nutrient use efficiency, and novel technologies required to promote sustainable agriculture and achieve the target of doubling farmer’s income in India

Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes

[EN] The increasing environmental concern and promotion of “green processes” are forcing the substitution of traditional acid and base homogeneous catalysts by solid ones. Among these heterogeneous catalysts, zeolites and zeotypes can be considered as real “green” catalysts, due to their benign nature from an environmental point of view. The importance of these inorganic molecular sieves within the field of heterogeneous catalysis relies not only on their microporous structure and the related shape selectivity, but also on the flexibility of their chemical composition. Modification of the zeolite framework composition results in materials with acidic, basic or redox properties, whereas multifunctional catalysts can be obtained by introducing metals by ion exchange or impregnation procedures, that can catalyze hydrogenation–dehydrogenation reactions, and the number of commercial applications of zeolite based catalysts is continuously expanding. In this review we discuss determinant issues for the development of zeolite based catalysts, going from zeolite catalyst preparation up to their industrial application. Concerning the synthesis of microporous materials we present some of the new trends moving into larger pore structures or into organic free synthesis media procedures, thanks to the incorporation of novel organic templates or alternative framework elements, and to the use of high-throughput synthesis methods. Post-synthesis zeolite modification and final catalyst conformation for industrial use are briefly discussed. In a last section we give a thorough overview on the application of zeolites in industrial processes. Some of them are well established mature technologies, such as fluid catalytic cracking, hydrocracking or aromatics alkylation. Although the number of zeolite structures commercially used as heterogeneous catalysts in these fields is limited, the development of new catalysts is a continuous challenge due to the need for processing heavier feeds or for increasing the quality of the products. The application of zeolite based catalysts in the production of chemicals and fine chemicals is an emerging field, and will greatly depend on the discovery of new or known structures by alternative, lower cost, synthesis routes, and the fine tuning of their textural properties. Finally, biomass conversion and selective catalytic reduction for conversion of NOx are two active research fields, highlighting the interest in these potential industrial applications.The authors acknowledge financial support from Ministerio de Ciencia e Innovacion (project Consolider-Ingenio 2010 MULTICAT).Martínez Sánchez, MC.; Corma Canós, A. (2011). Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes. Coordination Chemistry Reviews. 255(13-14):1558-1580. doi:10.1016/j.ccr.2011.03.014S1558158025513-1

Construction and Operation of an Experimental Setup for the Demonstration of Chemical Pumping in a Solar Thermochemical Process

Considering the huge potential and eco-friendly nature of solar energy, solar fuel production by means of two step water splitting redox cycles has gathered attention in the research community. Reaching high cycle efficiency is one of the biggest challenges towards the development of such process cycles. The non-stoichiometric reduction extent of the water splitting material heavily depends on the partial pressure of oxygen. By lowering the partial pressure of oxygen during the reduction, the non-stoichiometric reduction extent will be increased, which in turn increases the amount of fuel production. A novel method has been developed to increase the efficiency of the partial pressure reduction. In this method, the partial pressure of oxygen was lowered by thermochemical oxygen pumping at reduced total pressure. The main aim of this study is to demonstrate the working principle of the thermochemical oxygen pump. Initially, a piping and instrumentation diagram was created based on the process requirements. Based on that, the components/sensors has been selected and procured accordingly. The experimental test stand was later constructed by integrating all the components together. The acquisition and storage of the measured sensor values is carried out by means of a LabVIEW program created for the test stand with necessary data acquisition modules. The experiments were carried out in the presence/absence of the pumping material. During the re-oxidation step, a carrier gas containing 1040 ppm was passed through the splitting material. Based on the outlet Oxygen concentration measured by the mass spectrometer, the amount of oxygen absorbed by the Splitting material was calculated. From this value, the non-stoichiometric reduction extent of the Splitting material was evaluated. The experimental results indicate that there was no significant improvement in the reduction extent of the material. The air leakage and the diffusion factors were found to be the limiting factors for the implementation of this technology. The experiments and the analysis of the results helped to understand the insights of the pumping process and the limitations of the current system design. By carefully addressing the issues, it is foreseen to demonstrate this pumping process in the near future

Demonstration of thermochemical oxygen pumping for atmosphere control in reduction reactions

Solar thermochemical cycles as a means to produce fuels such as hydrogen, carbon monoxide, or syngas using a metal oxide as oxygen carrier offer a promising route to the efficient conversion and storage of solar energy. Even though the theoretical potential of such cycles can be very attractive, many challenges for reaching high process efficiencies remain unsolved. One challenging aspect is the parasitic energy cost for maintaining low partial pressures of oxygen during the reduction step. As previously proposed by the authors, thermochemical oxygen pumps have the theoretical potential to maintain low partial pressures of oxygen at considerably lower energy costs than conventional mechanical pumps. The work presented here demonstrates the proof of concept of thermochemical oxygen pumping. The reduction extents of a metal oxide after temperature swing experiments are analyzed for test runs with and without thermochemical oxygen pumping, clearly showing higher reduction extents for the former cases. The effects of different operational parameters on the reduction of the metal oxide are investigated and options for reduction extent enhancement are depicted