Guidance and control strategies for aerospace vehicles

A simplified method of matched asymptotic expansions was developed where the common part in composite solution is generated as a polynomial in stretched variable instead of actually evaluating the same from the outer solution. This methodology was applied to the solution of the exact equations for three dimensional atmospheric entry problems. Compared to previous works, the present simplified methodology yields explicit analytical expressions for various components of the composite solution without resorting to any type of transcendental equations to be solved only by numerical methods. The optimal control problem arising in the noncoplanar orbital transfer employing aeroassist was also addressed

Guidance and Control strategies for aerospace vehicles

A neighboring optimal guidance scheme was devised for a nonlinear dynamic system with stochastic inputs and perfect measurements as applicable to fuel optimal control of an aeroassisted orbital transfer vehicle. For the deterministic nonlinear dynamic system describing the atmospheric maneuver, a nominal trajectory was determined. Then, a neighboring, optimal guidance scheme was obtained for open loop and closed loop control configurations. Taking modelling uncertainties into account, a linear, stochastic, neighboring optimal guidance scheme was devised. Finally, the optimal trajectory was approximated as the sum of the deterministic nominal trajectory and the stochastic neighboring optimal solution. Numerical results are presented for a typical vehicle. A fuel-optimal control problem in aeroassisted noncoplanar orbital transfer is also addressed. The equations of motion for the atmospheric maneuver are nonlinear and the optimal (nominal) trajectory and control are obtained. In order to follow the nominal trajectory under actual conditions, a neighboring optimum guidance scheme is designed using linear quadratic regulator theory for onboard real-time implementation. One of the state variables is used as the independent variable in reference to the time. The weighting matrices in the performance index are chosen by a combination of a heuristic method and an optimal modal approach. The necessary feedback control law is obtained in order to minimize the deviations from the nominal conditions

Composition Operators and Classical Function Theory

(1) The section Linear Fractional Prologue is a context, to be consulted as needed , on the basic properties and classi�cation of linear fractional transformations. Linear fractional maps play a vital role in my work, both as agents for changing coordinates and transforming settings. (2) In the section Fourier series, I discuss how to construct a inner product from given Fourier series , the Dirichlet Kernel and its properties. Then I give the proof of Plancharal theorem and Parseval's theorem which play a good role through out my project. (3) This Littlewood's Theorem section is most important part of my work. After developing some of the basic properties of H2, here we shows that every composition operator acts boundedly on the Hilbert space. As pointed out above, this is essentially Littlewood's Subordination Principle. I present Littlewood's original proof - a beautiful argument that is perfectly transparent in its beauty, but utterly ba�ing in its lack of geometric insight. Much of conclusion can be regarded as an e�ort to understand the geometric underpinning of this theorem. (4) Having established that every composition operator is bounded on H2, we turn to the most natural follow-up question: "Which composition operators are compact?" The Chapter Compact- ness:Introduction sets out the motivation for this problem. The property of "boundedness" for composition operators means that each one takes bounded subsets of H2 to bounded subsets. The question above asks us to specify precisely how much the inducing map � has to compress the unit disc into itself in order to insure that the operator C� compresses bounded subsets of H2 into relatively compact ones. (5) In Chapter Compactness and Univalence we discover that the geometric soul of Littlewood's Theorem is bound up in the Schwarz Lemma. Armed with this insight, we are able to characterize the univalently induced compact composition operators, obtaining a compactness criterion that leads directly to the Julia-Caratheodory Theorem on the angular derivative. (6) In Chapter The Angular Derivative, I give the idea of the proof of Julia-Caratheodory Theorem in a way that emphasizes its geometric content, especially its connection with the Schwarz Lemma

Modification of silicon carbide fibers for use in SiC/Ti composites

The degradation of silicon carbide fibers during exposure to conditions typical of composite fabrication was investigated. The tensile strength of pristine fibers and fibers sputtered with thin metal coatings were determined before and after treatment at 870 C for one hour in vacuum. Each fiber strength distribution was related by an analytical procedure to a projected composite ultimate tensile strength (PC UTS). The results indicate that a thin aluminum diffusion barrier can yield a 150 percent increase in PC UTS over the baseline SiC/Ti system

Inflaton Decay in an Alpha Vacuum

We study the alpha vacua of de Sitter space by considering the decay rate of the inflaton field coupled to a scalar field placed in an alpha vacuum. We find an {\em alpha dependent} Bose enhancement relative to the Bunch-Davies vacuum and, surprisingly, no non-renormalizable divergences. We also consider a modified alpha dependent time ordering prescription for the Feynman propagator and show that it leads to an alpha independent result. This result suggests that it may be possible to calculate in any alpha vacuum if we employ the appropriate causality preserving prescription.Comment: 16 pages, 1 figure, Revtex 4 preprin

A BRIEF REVIEW ON CURRENT SCENARIO OF ANTI-DIABETIC AYURVEDIC REMEDIES

Ayurveda is not only an ancient medical science but it is a science which gives understanding about life. The scope of Ayurveda is to maintain the health of a healthy person and to cure those suffering from diseases.  Since last few decades due to drastic change in lifestyle, dietary habits and working pattern overall human population is facing increased burden of several diseases. Late night sleeping habits, increased fast food consumption, overeating and increased sugar intake are major changes observed in current era. Lifestyle disorder is a broad term given to all diseases which arises because of unhealthy lifestyle. Diabetes is the most common lifestyle disease affecting population worldwide at large. Now a day various researches carried out at different institutions found that variety of Ayurvedic drugs and therapies are successful in controlling diabetes, improving lifestyle of patient and thereby preventing further complications. The present review article is aimed at compiling data on promising Ayurvedic remedies that have been evaluated for their efficacy as an anti-diabetic remedy at various national and international institutions. This review article gives an idea about the efficiency of various anti-diabetic Ayurvedic treatment modalities in present era public

Effect of Bavistin and Silver Thiosulphate on In Vitro Plant Regeneration of Stevia rebaudiana

Effect of Bavastin (fungicide), Silver thiosulphate (Ehtylene inhibitor) on shoot regeneration using axillary bud explants of Stevia rebaudiana was studied.  In Bavastin supplemented medium multiple shoots were induced from axillary bud explants.  Bavistin in combination with BA induced maximum number of shoots (6.4±0.2).  Ethylene inhibitor silver thiosulphate also favoured the shoot morphogenesis. At lower concentration of silver thiosulphate (10-40 mM/L) maximum number of shoots (2.1-3.2) were obtained. All the in vitro raised shoots with a length of 3-5 cm were transferred to rooting medium.  The best rooting response was observed on 2.0mg/L IBA. The well rooted plantlets were transferred to polybags containing soil + vermiculite in 1: 1 ratio for hardening. Finally the hardened plantlets were transferred to field conditions for maximum survivability

Grama swarajya samithi - Visakhapatnam swachh bharath swachh Vidayala (SBSV) project

Grama Swarajya Samithi (GSS) is a non - governmental organization involved in various developmental activities in Visakhapatnam District and the focus groups are children, women, tribal, rural and urban disadvantaged communities for the last 20 years. The ‘Urban WASH - Swachh Bharat Swachh Vidyalaya’ project, a three-year project that aims to promote sanitation, effective use and ownership of school Water, Sanitation and Hygiene infrastructure in 20 GVMC schools in Vishakhapatnam city is implemented through GSS and the benefactors are Plan India, USAID and Coca Cola India Pvt. Ltd. Through this project, around 6,000 girls and boys from 20 Greater Visakha Municipal Corporation (GVMC) schools are getting access to potable water and safe sanitation. It will enhance the capacity of key stakeholders particularly the school children, teachers, School Management Committees (SMCs), functionaries and communities in performing their responsibilities for ensuring quality WASH in schools. The project interventions contribute to the Swachh Bharat Mission (SBM) through the Swachh Bharat Swachh Vidyalaya component. It will address school sanitation and importance of segregation waste into degradable and non-degradable wastes. The project will create replicable models for municipal corporation school improvement program

Nonlinear Optimal Tracking For Missile Gimbaled Seeker Using Finite-Horizon State Dependent Riccati Equation

The majority of homing guided missiles use gimbaled seekers. The equations describing seeker gimbal system are highly nonlinear. Accurate nonlinear control of the motion of the gimbaled seeker through the attached DC motors is required. In this paper, an online technique for finite-horizon nonlinear  racking problems is presented. The idea of the proposed technique is the change of variables that converts the nonlinear differential Riccati equation to a linear Lyapunov differential equation. The proposed technique is effective for wide range of operating points. Simulation results for a realistic gimbaled system with different engagement scenarios are given to illustrate the effectiveness of the proposed technique