The dynamics and optimal control of spinning spacecraft and movable telescoping appendages, part B: Effect of gravity-gradient torques on the dynamics of a spinning spacecraft with telescoping appendages

The effects of gravity gradient torques during boom deployment maneuvers of a spinning spacecraft are examined. Configurations where the booms extended only along the hub principal axes and where one or two booms are offset from the principal axes were considered. For the special case of symmetric deployment (principal axes booms) the stability boundaries are determined, and a stability chart is used to study the system behavior. Possible cases of instability during this type of maneuver are identified. In the second configuration an expression for gravity torque about the hub center of mass was developed. The nonlinear equations of motion are solved numerically, and the substantial influence of the gravity torque during asymmetric deployment maneuvers is indicated

Impact of Selenium Nanoparticles on Growth, Biochemical Characteristics and Yield of Cluster Bean Cyamopsis tetragonoloba

The present study deals with the impact of selenium nanoparticles on growth, biochemical characteristics and yield of Cluster bean Cyamopsis tetragonoloba grown for a period 60 days Sodium selenite and ascorbic acid was utilized for the synthesis of Selenium nanoparticles using precipitation method. Selenium nanoparticles were characterized by using SEM, EDAX, FTIR and XRD. Pot culture studies of cluster bean in different quantity of Selenium nanoparticles such as 0,100, 200, 300, 400 and 500mg for treatment T0 (Control) T1, T2, T3, T4 and T5 and growth biochemical and yield were estimated at the end of 60 days. SEM image of selenium nanoparticles was observed as spherical in shape. EDAX spectrum recorded on purity of selenium nanoparticles. The FTIR spectrum of selenium nanoparticles was analyzed in the range of 4000-400 cm-1 spectral bands were observed. The germination percentage in T0, T1, T2, T3, T4 and T5 are 100,90,80,90,100 and 100 respectively. Among the treatments the shoot length is higher (21.8) in T1 containing 100mg of selenium nanoparticles and lower in(12.01) T5 containing 500mg of nanoparticles. Root length, fresh and dry weight and leaf area were higher in T2. The vigor index is higher T4.The chlorophyll a, b total Chlorophyll, carotenoids, anthocyanin, protein, L-proline, free amino acids and leaf nitrate were higher inT4.Among the treatments yield of cluster bean is higher in T4 and lower in T0

Corporate Hierarchies and the Size of Nations: Theory and Evidence

Corporate organization varies within a country and across countries with country size. The paper starts by establishing some facts about corporate organization based on unique data of 660 Austrian and German corporations. The larger country (Germany) has larger firms with flatter more decentral corporate hierarchies compared to the smaller country (Austria). Firms in the larger country change their organization less fast than firms in the smaller country. Over time firms have been introducing less hierarchical organizations by delegating power to lower levels of the corporation. We develop a theory which explains these facts and which links these features to the trade environment that countries and firms face. We introduce firms with internal hierarchies in a Krugman (1980) model of trade. We show that international trade and the toughness of competition in international markets induce a power struggle in firms which eventually leads to decentralized corporate hierarchies. We offer econometric evidence which is consistent with the models predictions

Nitrogen Fertilization II: Management Practices to Sustain Crop Production and Soil and Environmental Quality

Improved management practices can be used to sustain crop yields, improve soil quality, and reduce N contaminations in groundwater and the atmosphere due to N fertilization. These practices include crop rotation, cover cropping, application of manures and compost, liming, and integrated crop-livestock system. The objectives of these practices are to reduce the rate of N fertilization, enhance N-use efficiency, increase crop N uptake, promote N cycling and soil N storage, and decrease soil residual N. This chapter discusses improved management practices to reduce N fertilization rate, sustain crop yields, and improve soil and environmental quality. The adaptation of these practices by farmers, producers, and ranchers, however, depends on social, economic, soil, and environmental conditions

Nitrogen Fertilization I: Impact on Crop, Soil, and Environment

Nitrogen (N) is a major limiting nutrient to sustain crop yields and quality. As a result, N fertilizer is usually applied in large quantity to increase crop production throughout the world. Application of N fertilizers has increased crop yields and resulted in achievement of self-sufficiency in food production in many developing countries. Excessive application of N fertilizers beyond crops’ demand, however, has resulted in undesirable consequences of degradation in soil, water, and air quality. These include soil acidification, N leaching in groundwater, and emissions of nitrous oxide (N2O), a potent greenhouse gas that contributes to global warming. Long-term application of ammonia-based N fertilizers, such as urea, has increased soil acidity which rendered to soil infertility where crops fail to respond with further application of N fertilizers. Another problem is the groundwater contamination of nitrate-N (NO3-N) which can be a health hazard to human and livestock if its concentration goes above 10 mg L−1 in drinking water. The third problem is emissions of N2O gas which is 300 times more powerful than carbon dioxide in terms of global warming potential. This chapter examines the effect of N fertilization on soil and environmental quality and crop yields

Characterization of high-Q optical microcavities using confocal microscopy

Confocal microscopy was initially developed to image complex circuits and material defects. Previous imaging studies yielded only qualitative data about the location and number of defects. In the present study, this noninvasive method is used to obtain quantitative information about the Q factor of an optical resonant cavity. Because the intensity of the fluorescent signal measures the number of defects in the resonant cavity, this signal is a measure of the number of surface scattering defects, one of the dominant loss mechanisms in optical microcavities. The Q of the cavities was also determined using conventional linewidth measurements. Based upon a quantitative comparative analysis of these two techniques, it is shown that the Q can be determined without a linewidth measurement, allowing for a noninvasive characterization technique

CYBER SECURITY SOLUTIONS FOR DLMS METERS USING GSM/GPRS TECHNOLOGY

The Smart meters are used in the areas of generation, transmission, distribution and consumption. The capabilities of smart meter systems and grid networks, such as distributed intelligence and broadband capabilities can greatly enhance efficiency and reliability, but they may also create much new vulnerability if not deployed with the appropriate security controls. Much of the technology currently in use by the meters are outdated and in many cases unreliable. A system architecture implementing should recognize security threats and capture events that result not from external threats but from internal mistakes, with human error being a more common occurrence. An effective security approach enhances reliability because some security failures might be people failures, while others might be equipment failures, might be due to natural causes or might be deliberate. A simple perimeter defense is not sufficient; monitoring, both for events and physical actions, is required to bring the benefits of smart meters with minimal risk to this vital part of the infrastructure of modern life