Motivated by the requirement for pinpoint landing in futureMarsmissions, we consider the problemofminimumfuel powered terminal descent to a prescribed landing site. The first-order necessary conditions are derived and interpreted for a point-mass model with throttle and thrust angle control and for rigid-bodymodel with throttle and angular velocity control, clarifying the characteristics of the...

average values of< 1- t >where t is the thrust are presented for e: e: amy data and are compared with their values in hadronic interactions. as far as possible, similar analysis techniques have been employed in the two different interactions. similar variation with e is observed for this average in both data. the values of < pt> and < pl > relative to the thrust axis in e e are similar to those...

allochthonous masses are common structures in zagros fold-thrust belt. they are generally considered as collapse structures formed by the influence of gravity and in rock units with competency contrast. however, large allochthonous masses mapped in dowgonbadan area in dezful embayment near the mountain front fault (mff) of zagros show characteristics different from the belt common collapse stru...

An integrated petrologic, thermochronologic, and numerical modeling study constrains the thermal evolution of the Lesser Himalayan Sequence in the Kumaun and Garwhal regions of India. South of the Tons thrust, peak metamorphic temperatures do not exceed 330 °C. On the northern side, a transition toward higher temperatures adjacent to the Main Central thrust hanging wall is documented. In the im...

A low-power microwave arjet thruster was studied using ammonia gas as propellant. The purpose of the project was to generate ammonia plasma using a 7.5 GHz magnetron and a cylindrical cavity thruster, which is resonant in the TM001 mode [1]. The desired pressure was atmospheric or above while generating a thrust of roughly 20mN and an Isp of about 500s operating at low power (<100 kW). Introduc...

The thrust and plasma parameters generated by a Helicon Double Layer Thruster operating at a power level of 250 W with krypton propellant has been evaluated for peak magnetic field strengths of 0 to 270 G. Results show that the thrust levels achieved are dependent on the position of peak magnetic field in relation to the plasma source. Alignment of peak field strength with the plasma source exi...

A retargeting procedure is developed for use as a nonlinear low thrust guidance scheme. The selection of a control program composed of a sequence of inertially fixed thrust-acceleration vectors permits all trajectory computations to be made with closed form expressions, and allows the controls to be represented by constant parameters, thrust-acceleration vectors and thrusting times. By requirin...

Speed and position control systems for marine vehicles have been subject to an increased focus with respect to performance and safety. An example is represented by drilling operations performed with semi submersible rigs where the control of position and heading requires high accuracy. Drifting from the well position could cause severe damage to equipment and environment. Also, the use of under...

Sandbox experiments with different boundary conditions demonstrate that antiformal stacks result from a forward-breaking thrust sequence. An obstacle blocks forward thrust propagation and transfers the deformation back to the hinterland in a previously formed true duplex. In the hinterland, continued shortening causes faults to merge toward the tectonic transport direction until the older thrus...

The aims of this study were to explore the hydrodynamic mechanism of Xenopus laevis swimming and to describe how hind limb kinematics shift to control swimming performance. Kinematics of the joints, feet and body were obtained from high speed video of X. laevis frogs (N=4) during swimming over a range of speeds. A blade element approach was used to estimate thrust produced by both translational...