Development of a unified guidance system for geocentric transfer

A method is presented for open loop guidance of a solar electric propulsion spacecraft to geosynchronsus orbit. The method consists of determining the thrust vector profiles on the ground with an optimization computer program, and performing updates based on the difference between the actual trajectory and that predicted with a precision simulation computer program. The motivation for performing the guidance analysis during the mission planning phase is discussed, and a spacecraft design option that employs attitude orientation constraints is presented. The improvements required in both the optimization program and simulation program are set forth, together with the efforts to integrate the programs into the ground support software for the guidance system

Mass study for modular approaches to a solar electric propulsion module

The propulsion module comprises six to eight 30-cm thruster and power processing units, a mercury propellant storage and distribution system, a solar array ranging in power from 18 to 25 kW, and the thermal and structure systems required to support the thrust and power subsystems. Launch and on-orbit configurations are presented for both modular approaches. The propulsion module satisfies the thermal design requirements of a multimission set including: Mercury, Saturn, and Jupiter orbiters, a 1-AU solar observatory, and comet and asteroid rendezvous. A detailed mass breakdown and a mass equation relating the total mass to the number of thrusters and solar array power requirement is given for both approaches

Modular thrust subsystem approaches to solar electric propulsion module design

Three approaches are presented for packaging the elements of a 30 cm ion thruster subsystem into a modular thrust subsystem. The individual modules, when integrated into a conceptual solar electric propulsion module are applicable to a multimission set of interplanetary flights with the space shuttle interim upper stage as the launch vehicle. The emphasis is on the structural and thermal integration of the components into the modular thrust subsystems. Thermal control for the power processing units is either by direct radiation through louvers in combination with heat pipes or an all heat pipe system. The propellant storage and feed system and thruster gimbal system concepts are presented. The three approaches are compared on the basis of mass, cost, testing, interfaces, simplicity, reliability, and maintainability

Effect of low thrust and earth oblateness orbit perturbations on the determination of the launch window for the SERT 2 mission

Procedures for determining launch window for SERT 2 mission and effect of low thrust and earth oblateness orbit perturbation

The Veterinary Identity: A Time and Context Model

The nature of professionalism teaching is a current issue in veterinary education, with an individual’s identity as a professional having implications for one’s values and behaviors, as well as for his or her career satisfaction and psychological well-being. An appropriately formed professional identity imparts competence in making complex decisions—those that involve multiple perspectives and are complicated by contextual challenges. It enables an individual to act in a way that aligns with his or her professional values and priorities, and imparts resilience to situations in which one’s actions are dissonant to these personal beliefs. There are challenges in professionalism teaching that relate to student engagement and faculty confidence in this area. However, these cannot be addressed without first defining the veterinary professional identity—in effect, the aim of professionalism teaching. In this article, existing identity models from the wider literature have been analyzed through a veterinary lens. This analysis was then used to construct a model of veterinary professional identity that incorporates the self (personal morals and values), social development (learning from the workplace environment), and professional behaviors. Individuals who form what we have termed self–environment–behavior connections are proposed to be able to use workplace learning opportunities to inform their identity development, such that environmental complexity does not obstruct the link between values and behaviors. Those who fail to connect with the environment in this way may perceive that environmental influences (e.g., the client, financial limitations) are obstructive to enacting their desired identity, and they may struggle with decision making in complex scenarios

Comparative Performance of Broiler Chickens Fed Varying Levels of

Abstract: Studies were conducted to compare the effects of dietary PKC and maize offal on the performance of broilers. According to the results of the trial with broiler starter chicks, the birds on the control diet (without PKC or maize offal) gave the highest body weight gain (1236.37g/bird). The result further showed that the birds on maize offal diets performed slightly better (1092.17 and 1005.56g/bird) than those on PKC diets (984.12 and 877.61g/bird). The birds on PKC diets consumed more feed (2446.11 and 2416.69g/bird) than those on maize offal diets (2329.05 and 2106.94g/bird). Feed cost per kg live weight gain was generally higher with PKC diets than with maize offal diets. Average daily water intake was not significantly affected by diets (200 to 300 ml/bird/day). Dry matter retention was higher with maize offal diets (66.45 and 68.52%) than with PKC diets (59.92 and 55.24%). The birds on the control diet gave almost similar crude protein and fat retention with those on maize offal diets (about 74%). The results of the trial with broiler finisher chickens indicated that weight gain per bird slightly decreased when PKC or maize offal replaced maize in the diet. Feed intake increased slightly when 50 % of dietary maize was replaced with PKC or maize offal. Feed to gain ratio increased significantly with the inclusion of PKC or maize offal in the diet. Water intake was not significantly affected by diets (400 to 500ml/bird/day). Dietary PKC significantly decreased dry matter retention. Crude protein retention was significantly higher in the maize offal diets (72.41 and 76.99%) as compared to PKC diets (59.91 and 64.25%). Fat retention significantly decreased with the test diets. From the foregoing, therefore, it can be concluded that both ingredients performed significantly well when compared to the control diet. However, maize offal seemed to have performed better than PKC in a number of parameters. Key words: Palm-kernel cake, maize offal, broiler chickens, soyabean mea

Importance of professional capabilities to veterinary medicine students

Adele Feakes, Jennifer Hyams, Martin Cake, Stuart Barber, ,, Blaise Webster, Edward Palmer, Dana A. Thomsen, Kiro R. Petrovsk

Gender and university differences in career sector and business intent of Australian veterinary students

Adele Feakes, Jennifer Hyams, Stuart Barber, Martin Cake,, Blaise Webster, Edward Palmer, Kiro R. Petrovski, , Dana A. Thomse