In this study, a method for designing a thermal optimum Reentry path based on aerodynamic database management has been developed using the Kriging and Co-Kriging methods. For the design of the Reentry path in the conceptual design phase, the more precise the dynamical model of the Reentry Vehicle, the closer the path is to reality. One of the issues affecting the accuracy of the dynamic model of return Vehicle is the aerodynamic coefficients in its flight envelope. For this purpose, in the present study using the new method, accurate aerodynamic data has been developed by combining the data from different solvers in the device flight envelope at the appropriate time. In the following, using the dynamic model and the developed Reentry path design algorithm, the thermal optimal return path of the Orion device with constant coefficients and the exact aerodynamic database are compared, and the important parameters of Reentry path, such as thermal flux and final velocity, are evaluated.

A numerical trajectory optimization study of two types of lifting-entry Reentry Vehicle has been presented at low suborbital speed of 4.113 km/s and -15 degree entry angle. These orbital speeds are typical of medium range ballistic missile with ballistic range of approximately 2000 km at optimum burnout angle of approximately 41 degree for maximum ballistic range. A lifting Reentry greatly enhances the Reentry range which leads to a higher overall range of approximately 3000 km for the same DV. The optimum Reentry angle of lifting Reentry Vehicle for medium range missiles under constrained g-load lies between -15 to -20 degree for limited g-load trajectories. These entry angles result in high decent rates and the Vehicle quickly approaches the heat rate boundary. The heat rate problem is more severe for small size Vehicle because of small nose-radius. Limiting the heat rate restricts the trajectory and lowers the downrange/cross-range performance of the Reentry Vehicle. A wing-body Reentry Vehicle has a larger nose radius as compared to a waverider which results in comparatively low heat rates during flight. This type of a Vehicle has lower lift-to-drag ratio and therefore lesser range in comparison to a waverider type design. The performance of the two Vehicle types is studied at various heat rate limits with the objective to calculate the optimum control deflections that would maximize the cross range. The results provide performance of the two designs vis-a-vis maximum heat rate constraint at the stagnation point along with the required control history. General pseudo-spectral optimal control software, GPOPS has been used for the optimal trajectory studies.

An explicit guidance law is developed for a Reentry Vehicle. Motion is constrained to a three-dimensional Bezier curve. Acceleration commands are derived by solving an inverse problem that combined with differential flatness approach. Trajectory is related to Bezier parameters. A comparison with pure proportional navigation shows the same accuracy, but a higher capability for optimal trajectory to some degree. Other advantages such as trajectory representation with minimum parameters, applicability to any Reentry Vehicle configuration and any control scheme, and Time-to-Go independency make this guidance approach more favorable.

An advanced guidance law is developed for Reentry phase of a Reentry Vehicle. It can achieve small miss distance and desired impact attitude angle, simultaneously. To meet this requirement, a guidance law based on the fuzzy logic control approach is developed. It is partitioned into three stages. This guidance law does not require linearization of missile engagement model. Line-of-sight angle and flight path angle are used to constitute the rule antecedent of the guidance law to shape an appropriate flight trajectory for engagement. Numerical simulation results and comparison with an existing algorithm demonstrated that the proposed guidance law offers satisfactory performance and robustness, fulfilling its design goals.

The robust multi-disciplinary, multi-objective shape optimization of re-entry capsule with aero-thermodynamic, trajectory, stability and the geometry considerations are presented in this paper. In this research, the results of maximizing the volumetric efficiency of the capsules while minimizing the ballistic coefficient and the longitudinal stability derivative with considering uncertainties are discussed in presence of some constraints on geometry, heating load, and load factor. To reduce the time and cost of robust optimization, the Adaptive Monte Carlo Simulation technique is used which decreases the number of required evaluations within the robust optimization process. Utilizing the constrained multi-objective genetic algorithm will result in a collection of robust optimal solutions. The results show that the performance of obtained robust optimal configurations is in a way that the considered constraints aren’ t violated with 99. 8% of confidence level even in the presence of uncertainties.

We present a 33 years-old smoker male with dyspnea on exertion, the cause of which was finally identified as atrial tachyarrhythmia after performing echocardiography, coronary angiography, right, and left sided cardiac catheterization During electrophysiology study; upper loop Reentry (ULR) a rare form of atypical Atrial flutter was diagnosed and ablated by conventional technique. New mapping technology improved our understanding of the mechanism and pathways of arrhythmia, and allowed complex ablations made easier and more cost-effective.

This study is dedicated to the solution of the inverse heat conduction problem for estimation of the time-varying velocity and altitude profiles regarding the flight trajectory of an earth-entry capsule. Four tungsten-rhenium sensors are supposed to be embedded inside the ablative heat shield of the probe, three of which cannot tolerate high-temperature conditions and burn out during entry and the other one remained intact until the end of the simulation. The conventional Levenberg-Marquardt method is reinforced by a relaxation scheme to prevent unfavorable severe oscillations encountered in the inverse iterations. To keep the generality of the method, no prior knowledge on the thermal condition and surface recession of ablative insulator is utilized in the current estimation. Therefore, in the associated direct problem, velocity and altitude profiles are given and the temperature field inside the heat shield is determined. Accordingly, a solution of the direct problem consists of (i) bow shock calculations in dissociated air (ii) boundary layer solver to compute stagnation heating rate (iii) identification of the thermal response of charring ablative heat shield. It is shown that if the standard deviation of the temperature measurement error is 5 K, estimation of altitude and velocity are associated with approximately 10 and 5 percent normalized error, respectively.

Optimal trajectory planning is an important task which is required in most of guidance missions. This paper introduces a new method that utilizes the most important characteristics of global optimization methods along with a new gradient -based method in a two layered scheme for the trajectory planning. In the first layer to construct a convenient shooting method based algorithm, some of the most important global methods of optimization are used in an information transform structure. Exchanging the information between selected algorithms helps for increasing the efficiency of problem solving. To do this, a comprehensive model for parameterization of the control history is introduced which allows the method to search for the best profile in a variety of different profiles. Results of this layer are transformed to the second layer that uses one of direct methods of solving the optimal control problems. This gradient based method named Radau pseudospectral method using of the results of global methods, completes the optimization process. Finally, developed algorithm is used to find the optimal trajectory of a Reentry capsule and effects of the path constraint values on the total heat absorbed is investigated.