Atmospheric Reentry Dispersion Correction Ascent Phase Guidance for a Generic Reentry Vehicle

Launch vehicle explicit guidance mechanism depends on the estimation of the desired burnout conditions and driving the vehicle to achieve these conditions. The accuracy of the vehicle at the target point depends on how tightly these conditions are achieved and what is the strategy used to define the trajectory. It has been observed inthe literature that most of the guidance mechanisms during reentry use vacuum guidance equations that is durin greentry the atmospheric effects are not considered. In order to achieve minimum miss distance at the target point theat mospheric effects are to be considered during the guided phase and appropriate corrections should be executed,otherwise depending on the reentry flight path angle and ballistic coefficient the errors can be as high as tens of nautical miles. In this paper, the authors develop a novel approach to these vacuum guided launch vehicle problems.The paper elaborates how to calculate a prior the reentry dispersion during the ascent phase guidance and provide guidance corrections such that the terminal conditions are achieved with higher accuracy.Defence Science Journal, 2013, 63(3), pp.233-241, DOI:http://dx.doi.org/10.14429/dsj.63.373

Real Time Mid-course Maneuver and Guidance of a Generic Reentry Vehicle

The aim of any mission is to accomplish the final objective with desired accuracy and the same is valid for a generic launch vehicle. In many missions it is necessary to execute mid-course maneuvers with an intentional diversion trajectory to create a counter measure or to avoid certain specific known geographical locations. The current work elaborates a novel and practically implementable mid-course maneuver and an ascent phase guidance of a reentry vehicle executing an in-flight determined mid-course maneuver (trajectory reshaping) without compromising the accuracy of the final achieved target position. The robustness of the algorithm is validated with 6DoF simulation results by considering the dispersion of the burnout state vector conditions which arises due to variations in thrust profile, aerodynamics characteristics of the vehicle, atmosphere, etc.Defence Science Journal, 2013, 63(4), pp.346-354, DOI:http://dx.doi.org/10.14429/dsj.63.420

Secretagogues of lung surfactant increase annexin A7 localization with ABCA3 in alveolar type II cells

AbstractMembrane fusion between the lamellar bodies and plasma membrane is an obligatory event in the secretion of lung surfactant. Previous studies have postulated a role for annexin A7 (A7) in membrane fusion during exocytosis in some cells including alveolar type II cells. However, the intracellular trafficking of A7 during such fusion is not described. In this study, we investigated association of endogenous A7 with lamellar bodies in alveolar type II cells following treatment with several secretagogues of lung surfactant. Biochemical studies with specific antibodies showed increased membrane-association of cell A7 in type II cells stimulated with agents that increase secretion through different signaling mechanisms. Immuno-fluorescence studies showed increased co-localization of A7 with ABCA3, the lamellar body marker protein. Because these agents increase surfactant secretion through activation of PKC and PKA, we also investigated the effects of PKC and PKA inhibitors, bisindolylmaleimideI (BisI) and H89, respectively, on A7 partitioning. Western blot analysis showed that these inhibitors prevented secretagogue-mediated A7 increase in the membrane fractions. These inhibitors also blocked increased co-localization of A7 with ABCA3 in secretagogue-treated cells, as revealed by immuno-fluorescence studies. In vitro studies with recombinant A7 showed phosphorylation with PKC and PKA. The cell A7 was also phosphorylated in cells treated with surfactant secretagogues. Thus, our studies demonstrate that annexin A7 relocates to lamellar bodies in a phosphorylation-dependent manner. We suggest that activation of protein kinase promotes phosphorylation and membrane-association of A7 presumably to facilitate membrane fusion during lung surfactant secretion

Atmospheric Reentry Dispersion Correction Ascent Phase Guidance for a Generic Reentry Vehicle

<!-- @page { margin: 2cm } P { margin-bottom: 0.21cm } --> <p style="margin-bottom: 0cm;">Launch vehicle explicit guidance mechanism depends on the estimation of the desired burnout conditions and driving the vehicle to achieve these conditions. The accuracy of the vehicle at the target point depends on how tightly these conditions are achieved and what is the strategy used to define the trajectory. It has been observed inthe literature that most of the guidance mechanisms during reentry use vacuum guidance equations that is durin greentry the atmospheric effects are not considered. In order to achieve minimum miss distance at the target point theat mospheric effects are to be considered during the guided phase and appropriate corrections should be executed,otherwise depending on the reentry flight path angle and ballistic coefficient the errors can be as high as tens of nautical miles. In this paper, the authors develop a novel approach to these vacuum guided launch vehicle problems.The paper elaborates how to calculate a prior the reentry dispersion during the ascent phase guidance and provide guidance corrections such that the terminal conditions are achieved with higher accuracy.</p><p style="margin-bottom: 0cm;"><strong>Defence Science Journal, 2013, 63(3), pp.233</strong><strong>-241<strong>, <a>DOI:http://dx.doi.org/10.14429/dsj.</a>63.3733</strong></strong></p