51 research outputs found
Published In : Proceedings: National Agronomy Congress on “Redesigning Agronomy for Nature Conservation and Economic Empowerment”, Pantnagar Agronomy Society held at GBPUA&T, Pantnagar, 20-22 February 2018. pp: 570-572.
No full textSher Singh; Mahanta, D.; Tuti, M.D.; Panday, S.C.; Mondal, T.; Yadav, R.P.; Meena, V.S. and Choudhary, M. 2018. Enhancing productivity and profitability of rainfed wheat with thiourea and dew harvesting in North-western Himalayas. In : Proceedings: National Agronomy Congress on “Redesigning Agronomy for Nature Conservation and Economic Empowerment”, Pantnagar Agronomy Society held at GBPUA&T, Pantnagar, 20-22 February 2018. pp: 570-572.Not AvailableNot Availabl
Dealing with clay when mining diamonds offshore: High rate mining tool development
No full textDe Beers Marine is currently mining diamonds offshore near the Namibian coast (at water depths of 115 - 140 meters), using a vertical batch drill mining system ('Wirth drill"). Previously also continuous seabed crawlers have been used, but this method was discontinued because of unsatisfactory operational performance and recovery of the diamonds. New crawler-type mining tools (latest tool is the so-called "Gravel Wheel") are being developed due to their higher mining rate potential compared to the Wirth drill. On 1/3 scale different versions of the Gravel Wheel had been thoroughly tested on imitated seabeds of gravel and initial tests had been done in clay. Since together with the gravel on average 5 to 10 cm (up to 30 cm) of underlying clay footwall may have to be loosened and removed more thorough tests have to be done in clay. The first reason to study the cutting into clay is the irregular gravel-footwall interface, which makes it nearly impossible to stay right at this interface all the time. Secondly, 100% of the diamonds have to be removed since the likelihood of diamonds occurring at the gravel-footwall interface is high. With the Gravel Wheel currently being tested, the focus of this study is to mine both gravel and clay with one tool in one step. The main objective of this study is to define and improve the clay handling ability of the current Gravel Wheel model MkIII through scaled testing. The clay handling ability is specified as the ability to remain 100% clear from blockages and the ability to penetrate the clay footwall for 50 mm (full scale) whilst mining gravel. To reach to goals set, sub-objectives set are to establish a proper theoretical basis for the execution of scaled tests in clay, as well as derive basic design guidelines from experience in other related industries in order to evaluate and improve the Gravel Wheels' clay handling ability. In the attempt to achieve similarity between model and full scale, three scenarios for scaled testing are identified. Although all three show scale effects, the most favourable scenario is selected to perform scaled tests. The main drawback of this scenario is that the clays' shear strength is not scaled back correctly in ratio to the force to mould the cut clay lumps (drag force). The consequence is that the test conditions on model scale are much tougher than on full scale. It is argued that if this scenario is used in scaled testing and if testing is successful, the tool will definitely work on full scale. From experience in dredging several design guidelines have been derived to evaluate a tools' clay cutting ability and an initial evaluation of the Gravel Wheel has been made. The Gravel Wheel scores negative on the risk of bulldozing, openness of the tool and the converging shape of the suction duct and these features are expected to be most critical in the Gravel Wheels' design. Based on this analysis the scoop grizzly has been modified to reduce the risk of bulldozing. The scaled tests (continued on 1/3 scale) prove that the maximum cut depth at which the tool remains free from blockage increases with increased rotational speed and modified scoop design. On model scale a 100 mm cut in clay has been achieved with a rotational speed of 20 RPM and a modified scoop design. Tests show that while mining gravel, a 20 mm and 50 mm cut in clay can be achieved at forward mining speeds of 2.5 and 1.7 m/min respectively. Further modifications to the scoop are made to reduce the obstructing side effect of the grizzly bars. The test results confirm that the risk of bulldozing and the converging shape of the suction duct are the most critical features in the Gravel Wheels design. The obstructing side effect of the grizzly bars has also been recognized as problematic. It is recommended that more shear strength testing is done on offshore footwall clays to get more insight in the actual clay footwall shear strengths since currently only limited shear strength data of the clay footwall is available. Further more tests in clay and gravel should be performed to find the optimum operational parameters (e.g. forward mining speed) at different set cut depths: initial tests in clay and gravel have proven valuable to study the clay and gravel interaction and initial trends have been observed. The necessity to achieve a specific cut depth in clay depends all on the degree of undulation and the accuracy with which the clay-gravel interface can be followed. It is therefore finally recommended to further study these factors in order to better define the clay cut depth requirement of any mining tool.Applied GeologyGeoscience & EngineeringCivil Engineering and Geoscience
4D Trajectory De-Confliction For Future ATM By Applying Constraints
No full textIn the present ATC system conflicts between aircraft are detected and resolved in a stated-based approach. To meet traffic demand predictions, the global air traffic management (ATM) system needs revolutionary changes. Several visions on future ATM operations exist (e.g. NextGen, SESAR). A common function between the different visions is 4D Trajectory management. This function enables trajectory-based operation as opposed to the state-based approach of the present system. Instead of monitoring the current traffic situation and resolving short term conflicts by vectoring, the 4D trajectory management function de-conflicts all trajectories prior to execution. A key function of 4D trajectory management is the resolution of 4D trajectories. Conflict resolution of 4D trajectories is applied to conflict scenarios using constraints. A characteristic of a constraint is that it does not limit the aircraft to a particular solution but provides the aircraft the room to generate a trajectory within the actual solution space. Conflicting trajectories are resolved using constraints where the constraints provides an approximation of the solution space. This concept of trajectory de-confliction through the use of constraints is the topic of this thesis work.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
The diurnal cycle of air pollution in the Kathmandu Valley, Nepal
No full textThesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 213-230).This dissertation describes the most comprehensive study to date of the diurnal cycle of air pollution in the Kathmandu Valley, Nepal -- a bowl-shaped mountain valley of two million people with a growing air pollution problem but little past research. Field measurements and computer simulations were used to study the interplay of emissions and ventilation. From September 2004 through June 2005, CO (carbon monoxide), ozone, PM10 (particles smaller than 10 micrometers), wind speed and direction, solar radiation, temperature, and humidity were continuously measured east of Kathmandu. Sensors towers and mountains measured the diurnal cycle of the vertical temperature structure and stability. A sodar measured the mixed layer height and upper-level winds. Bag sampling provided the diurnal cycle of CO on mountains, passes and around the valley. Winds were measured on a mountain pass and ozone on a mountaintop. Patterns of air pollution and meteorology in the valley showed remarkable day-to-day similarity, with daily twin peaks of CO and PM10, a noon ozone maximum, afternoon westerly winds, and a stagnant cold pool at night. On mountaintops at night, ozone remained high, while CO dropped to regional background levels.(cont.) The meso-scale meteorological model MM5 was adapted to the Kathmandu Valley for days in February and May 2005. It was able to capture the essential features of the valley's meteorology and was used to address three specific questions: The break-up of the valley's temperature inversion was found to be dominated in February by up-slope winds on the valley rim, plus subsidence over the valley center; in May surface heating of the valley bottom also played a major role. The pathways of pollutant transport out of the valley were found to be up the valley rim slopes in the morning, but out the eastern and southern passes in the afternoons. At night pollutants remained within the valley except near the river outlet. They were lifted off the ground at night and re-circulated in the morning. The eulerian chemistry transport model CAMx, was used in tracer mode, with MM5 meteorology to simulate the emission, transport and removal of CO from the Kathmandu Valley. The simulations were limited by the accuracy of Kathmandu's emissions inventory, especially the spatial distribution of emissions.by Arnico K. Panday.Sc.D
Caribbean Report 06-06-1996
No full text1. Headlines (00:00-00:27)2. Nominations go ahead in Trinidad and Tobago for local government elections. Patrick Manning of the People's National Movement and Prime Minister Basdeo Panday are interviewed. Tony Fraser reports (00:28-02:50)3. There has been another verbal exchange over the Helms-Burton Law. N. Perez of the Foundation which represents Cuban exiles in the United States, Canadian Secretary of State for Latin America Christie Steward and OAS Assistant Secretary General Christopher Thomas of Trinidad and Tobago are interviewed. Moya Thomas reports (02:51-07:46)4. In Washington the US House of Representatives has amended an aid bill for Haiti. The Director of the United States Agency for International Development Brian Atwood is interviewed (07:47-09:02)5. Haitian President Rene Preval was expected to arrive in France today on the leg of the Europe tour for talks with his French counterpart Jacques Chirac (09:03-09:37)6. Nation of Islam Leader Louis Farrakhan is again scheduled to visit Jamaica later this month. He has been invited to help Mustard Seed an organisation that provides help for the needy, including youths and the elderly. Radio Jamaica General Manager Hugh Crosskill is interviewed (09:38-13:15)7. Examining what some see as unjustified criticism of successful West Indian cricketers. Author Michelle Savage is interviewed (13:16-15:18
Comparative assessment of turbulence model in predicting airflow over a NACA 0010 airfoil
No full textRemoção de íons metálicos em água utilizando diversos adsorventes
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia QuímicaEste trabalho teve como objetivo avaliar a capacidade de adsorção de adsorventes de baixo custo como argila ativada montmorilonita, carvão mineral (ROM) e schungite na remoção de íons Fe2+ , Mn7+, Cr6+, Cu2+, e Zn2+ em solução aquosa. O cromo e o manganês encontravam-se em solução na forma de ânion CrO2+4 e MnO1-7 , e os demais íons na forma de cátions. Os testes de remoção dos íons metálicos em solução foram realizados nas temperaturas de 25°C, 30°C e 35ºC, em pH ajustado para 6,0 +/- 0,2 em frascos fechados sob agitação de 125 rpm, utilizando-se soluções modelo contendo esses íons. Todos os testes de adsorção foram também realizados com o carvão ativado comercial (GAC) nas mesmas condições, para comparação dos resultados ecom os adsorventes de baixo custo. As isotemas de adsorção foram utilizadas segundo a classificação de Brunauer. Os parâmetros de adsorção para as isotermas de Langmuir e Freundlich foram obtidas para os dados experimentais de cada íon metálico utilizado sobre todos os adsorventes. Os parâmetros de BET foram obtidos apenas para os resultados experimentais da adsorção do Mn7+ sobre os adsorventes: argila ativada montmorilonita, schngite e carvão ativado (GAC). A constante de equilíbrio de Freundlich (Kf), a diferentes temperaturas permitiu calcular a entalpia de adsorção através da equação de Clausius-Clapeyron. Os valores da entalpia de adsorção encontrados indicam adsorção física. Isso indica que o processo é exotérmico. Porém na faixa de temperatura utilizada 25°C a 35°C não observou-se variações significativas na adsorção dos íons metálicos. A realização desta pesquisa foi motivada pelo interesse e necessidade em solucionar ou minimizar problemas de íons metálicos em águas existentes em determinados locais da região do meio oeste de Santa Catarina. O carvão mineral (ROM) e o schungite utilizados, apresentam alto teor de cinza e carbono fixo relativamente baixo quando comparados ao carvão comercial (GAC). Os resultados mostraram que os adsorventes de baixo custo testados neste trabalho podem substituir o carvão ativado comercial (GAC) cujo custo é bem mais alto. Porém observou-se pelos dados experimentais que a capacidade de adsorção varia de um adsorvente para outro, ao adsorver íon metálico nas mesmas condições. Isto ocorre porque cada adsorvente tem características específicas e que interferem na afinidade entre adsorvente e adsorbato. Daí a importância de conhecer os poluentes que deseja-se remover bem como as características do adsorvente. Em certos casos pode-se utilizar a mistura de dois ou mais adsorventes de baixo custo para obter-se resultados satisfatórios
Caracterização química e reatividade de substâncias húmicas, solos e turfas
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em QuímicaAmostras de solos, turfas e suas substâncias húmicas (SH) foram caracterizadas através de análise termogravimétrica (TG), análise elementar, espectroscopia de infravermelho (IV) e ressonância magnética nuclear de 13C (RMN 13C). Os resultados demonstraram que as amostras de matéria orgânica (MO) apresentaram uma estrutura mais alifática e rica em polissacarídeos do que suas SH. Entretanto, as razões atômicas assim como a IV e RMN 13C puderam ser usadas para caracterizar e diferenciar amostras de MO. A acidez de SH de ambientes distintos foi determinada pela titulação indireta. Os resultados geraram dúvidas com relação à validade da metodologia e de possíveis interferências ocasionadas pelas características das amostras. Desta forma, experimentos foram idealizados para testar a validade dos valores de acidez de SH determinados por diferentes métodos e tratados por diferentes modelos matemáticos. Os resultados de acidez mostraram dependência do modelo aplicado e das condições experimentais. A remoção do azul de metileno (AM), do 17ß-estradiol e do 17a-etinilestradiol de soluções aquosas pela turfa foi avaliada. Para o AM, a remoção foi maior para as soluções diluídas. Para os hormônios, a turfa apontou ser uma alternativa viável nos testes de adsorção. A turfa mostrou-se eficiente, demonstrando a sua potencialidade para a recuperação de efluentes contaminados com estes compostos
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