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A research programme has been conducted, the objective of which has been the determination of unsteady force coefficients for a range of parachute canopy models. These coefficients are required for prediction of the aerodynamic stability of full scale parachutes under conditions of unsteady motion during descent. The method of obtaining these coefficients required the collection of force and acceleration data for parachute canopy models which were tested in unsteady conditions. This was achieved by imposing oscillatory motion on individual canopies during towing tests, which were conducted under water in a ship testing tank. Two modes of unsteady motion were imposed on a canopy under test; one in which it was oscillated along its axis, and one in which it was oscillated laterally. A mathematical model describing such modes of motion consists of a general equation for the unsteady force developed on a bluff body. In this model the force F(t) is expressed using two components; a velocity dependent force component, and an acceleration dependent force component. Each component of the aerodynamic force contains an unknown parameter denoted by the terms ‘a’ and ‘b’ in the equation, which is shown below; F( t ) = a( t ) • V²( t ) + b( t ) • V( t ). An identification technique is used to determine the mean values per cycle of each parameter by substitution of the data obtained from these tests as functional variables in the mathematical model. Mean values of the velocity dependent force and stability coefficients; CT and ∂CN/∂α, and the added mass coefficients k11 and k33 are then obtained from these parameters. The results of this programme indicate a strong dependence in oscillatory motion of the mean value per cycle for the axial added mass coefficient k11 on the unsteady force parameter called the Keulegan-Carpenter number KC; KC = Û • T/DO. Where; Û = the velocity amplitude of the oscillation, T = the period of an oscillation, and DO = a typical canopy dimension. The velocity dependent axial force coefficient CT exhibits a similar, although not as substantial dependency. Good agreement has been obtained between steady-state test results from this programme and results from other independent work. The effects of values obtained in this investigation are considered in the linearised dynamic stability model developed by Doherr and Saliaris (1), and their influence on the descent characteristics of full-scale parachutes is assesed.

Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: parachute shedding characteristics; near wake evolution; parachute inflation; canopy breathing; velocity field measurements. Includes bibliographical references (p. 126-131).

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 106-107).

To increase aerodynamic performance, the geometric porosity of a ringsail spacecraft parachute canopy is sometimes increased, beyond the "rings" and "sails" with hundreds of "ring gaps" and "sail slits." This creates extra computational challenges for fluid--structure interaction (FSI) modeling of clusters of such parachutes, beyond those created by the lightness of the canopy structure, geometric complexities of hundreds of gaps and slits, and the contact between the parachutes of the cluster. In FSI computation of parachutes with such "modified geometric porosity," the flow through the "windows" created by the removal of the panels and the wider gaps created by the removal of the sails cannot be accurately modeled with the Homogenized Modeling of Geometric Porosity (HMGP), which was introduced to deal with the hundreds of gaps and slits. The flow needs to be actually resolved. All these computational challenges need to be addressed simultaneously in FSI modeling of clusters of spacecraft parachutes with modified geometric porosity. The core numerical technology is the Stabilized Space--Time FSI (SSTFSI) technique, and the contact between the parachutes is handled with the Surface-Edge-Node Contact Tracking (SENCT) technique. In the computations reported here, in addition to the SSTFSI and SENCT techniques and HMGP, we use the special techniques we have developed for removing the numerical spinning component of the parachute motion and for restoring the mesh integrity without a remesh. We present results for 2- and 3-parachute clusters with two different payload models. We also present the FSI computations we carried out for a single, subscale modified-porosity parachute.

Ballute hypersonic aerodynamic decelerators have been considered for aerocapture since the early 1980's. Recent technology advances in fabric and polymer materials as well as analysis capabilities lend credibility to the potential of ballute aerocapture. The concept of the thin-film ballute for aerocapture shows the potential for large mass savings over propulsive orbit insertion or rigid aeroshell aerocapture. Several technology hurdles have been identified, including the effects of coupled fluid structure interaction on ballute performance and survivability. To date, no aeroelastic solutions of thin-film ballutes in an environment relevant to aerocapture have been published. In this investigation, an aeroelastic solution methodology is presented along with the analysis codes selected for each discipline. Variable-fidelity aerodynamic tools are used due to the long run times for computational fluid dynamics or direct simulation Monte Carlo analyses. The improved serial staggered method is used to couple the disciplinary analyses in a time-accurate manner, and direct node-matching is used for data transfer. In addition, an engineering approximation has been developed as an addition to modified Newtonian analysis to include the first-order effects of damping due to the fluid, providing a rapid dynamic aeroelastic analysis suitable for conceptual design. Static aeroelastic solutions of a clamped ballute on a Titan aerocapture trajectory are presented using non-linear analysis in a representative environment on a flexible structure. Grid convergence is demonstrated for both structural and aerodynamic models used in this analysis. Static deformed shape, drag and stress level are predicted at multiple points along the representative Titan aerocapture trajectory. Results are presented for verification and validation cases of the structural dynamics and simplified aerodynamics tools. Solutions match experiment and other validated codes well. Contributions of this research include the development of a tool for aeroelastic analysis of thin-film ballutes which is used to compute the first high-fidelity aeroelastic solutions of thin-film ballutes using inviscid perfect-gas aerodynamics. Additionally, an aerodynamics tool that implements an engineering estimate of hypersonic aerodynamics with a moving boundary condition is developed and used to determine the flutter point of a thin-film ballute on a Titan aerocapture trajectory.

Currently, simulation predictions of the Orion Crew Module (CM) dynamics with drogue parachutes deployed are under-predicting the amount of damping as seen in free-flight tests.  The Apollo Legacy Chute Damping model has been resurrected and applied to the Orion system. The legacy model has been applied to predict CM damping under drogue parachutes for both Vertical Spin Tunnel free flights and the Pad Abort-1 flight test.  Comparisons between the legacy Apollo prediction method and test data are favorable.  A key hypothesis in the Apollo legacy drogue damping analysis is that the drogue parachutes' net load vector aligns with the CM drogue attachment point velocity vector.  This assumption seems reasonable and produces good results, but has never been experimentally verified.  The wake of the CM influences the drogue parachutes, which makes performance predictions of the parachutes difficult.  Many of these effects are not currently modeled in the simulations. A forced oscillation test of the CM with parachutes was conducted in the NASA LaRC 20-Ft Vertical Spin Tunnel (VST) to gather additional data to validate and refine the Apollo legacy drogue model.  A second loads balance was added to the original Orion VST model to measure the drogue parachute loads independently of the CM.  The objective of the test was to identify the contribution of the drogues to CM damping and provide additional information to quantify wake effects and the interactions between the CM and parachutes.  The drogue parachute force vector was shown to be highly dependent on the CM wake characteristics.  Based on these wind tunnel test data, the Apollo Legacy Chute Damping model was determined to be a sufficient approximation of the parachute dynamics in relationship to the CM dynamics for preliminary entry vehicle system design.  More wake effects should be included to better model the system. These results are being used to improve simulation model fidelity of CM flight with drogues deployed, which has been identified by the project as key to a successful Orion Critical Design Review. / Master of Science

Abstract This essay is a study on "the influence that the stock options of the salary incentive pay system have on the management level of Chinese mainland insurance industry". this study is divided into four parts : first , introduce the theory that influence the setting of the salary incentive pay system ; second, analyses the common-used incentive pay system in Chinese mainland at present and its developmental tendency ; third , introduce the basic information of Taiwan's insurance industry brought into mainland . We hope that the study on mainland's insurance industry will contribute to the Taiwan' study in the field of mainland' insurance market. Fourth, analyze how Taiwan's insurance industry establish salary incentive pay system that meet the market demands in their development in mainland . The stereotype of the industrialist, the collected data, the careful analysis and the case that was picked out, can be referred to by those who want to develop on the mainland market. From this study, we find that there are active effects of thestock options system from the salary incentive pay system, whichcannot be found in the mainland's intermediate insurance industry. The cause can be concluded into two species: individual factor, externalfactor. Each conclusion has three items. So there are totally sixitems. The conclusions suggest that, mainland's intermediate insurance companies' planning on the management's salary incentive pay system is faced with many influence factors now. Althongh there are some limitations of the annual salary, such as the management behaviors Short-termism, the frequently-liquid of the managements' talents, the shortage of management talents, still, the effects are more active than other incentive pay system forms such as manager acquisition, insurance plan and retire plan, golden parachutes and EVA, except stock rights and options. The key words : the salary incentive pay system; management; Chinese mainland insurance market; stock options; golden parachutes

Airdrop systems provide a unique capability of delivering large payloads to undeveloped and inaccessible locations. Traditionally, these systems have been unguided, requiring large landing zones and drops from low altitude. The invention of the steerable, gliding, ram-air parafoil enabled the possibility of precision aerial payload delivery. In practice, the gliding ability of the ram-air parafoil can actually create major problems for airdrop systems by making them more susceptible to winds and allowing them to achieve far greater miss distances than were previously possible. Research and development work on guided airdrop systems has focused primarily on evolutionary improvements to the guidance algorithm, while the navigation and control algorithms have changed little since the initial autnomous systems were developed. Furthermore, the control mechanisms have not changed since the invention of the ram-air canopy in the 1960's. The primary contributions of this dissertation are: 1) the development of a reliable and robust method to identify a flight dynamic model for a parafoil and payload aircraft using minimal sensor data; 2) the first demonstration in flight test of the ability to achieve large changes in glide slope over ground using coupled incidence angle variation and trailing edge brake deflection; 3) the first development of a control law to implement glide slope control on an autonomous system; 4) the first flight tests of autonomous landing with a glide slope control mechanism demonstrating an improvement in landing accuracy by a factor of 2 or more in especially windy conditions, and 5) the first demonstrations in both simulation and flight test of the ability to perform in-flight system identification to adapt the internal control mappings to flight data and provide dramatic improvements in landing accuracy when there is a significant discrepancy between the assumed and actual flight characteristics.

With the advent of steerable, ram air parafoil canopies, aerial payload delivery has become a viable alternative for situations involving remote or undeveloped areas, hostile environments, or otherwise inaccessible locations. Autonomously guided systems utilizing such steerable, ram air canopies are typically controlled by symmetric and asymmetric deflection of the canopy trailing edge. Although these systems have demonstrated substantial improvement in landing accuracy over similarly sized unguided systems, their low number of available control channels and limited ability to alter vehicle glide slope during flight makes them highly susceptible to atmospheric gusts and other unknown conditions near the target area. This research aims to improve landing accuracy in such adverse conditions by replacing the standard trailing edge deflection control mechanism in favor of upper surface canopy spoilers. These spoilers operate by opening several spanwise slits in the upper surface of the parafoil canopy thus forming a virtual spoiler from the stream of expelled pressurized air. In particular, estimation of steady-state vehicle flight characteristics in response to different symmetric and asymmetric spoiler openings was determined for two different small-scale test vehicles. Additionally, improvements in autonomous landing accuracy using upper surface spoilers in a combined lateral and longitudinal control scheme was investigated computationally using a high fidelity, 6-DOF dynamic model of the test vehicle and further validated in actual flight experiments with good results. Lastly, a novel in-canopy bleed air actuation system suitable for large-scale parafoil aircraft was designed, fabricated, and flight-tested. The in-canopy system consists of several small, specifically designed wireless winch actuators mounted entirely inside the parafoil canopy. Each in-canopy actuator is capable of opening one or more upper surface canopy spoilers via a unique internal rigging structure. This system demonstrates not only the applicability of bleed air spoiler control for large-scale autonomous parafoil and payload aircraft, but also provides the potential for significant savings in size, weight, and cost of the required actuation hardware for currently fielded systems.