High-temperature optically activated GaAs power switching for aircraft digital electronic control

Gallium arsenide high-temperature devices were fabricated and assembled into an optically activated pulse-width-modulated power control for a torque motor typical of the kinds used in jet engine actuators. A bipolar heterojunction phototransistor with gallium aluminum arsenide emitter/window, a gallium arsenide junction field-effect power transistor and a gallium arsenide transient protection diode were designed and fabricated. A high-temperature fiber optic/phototransistor coupling scheme was implemented. The devices assembled into the demonstrator were successfully tested at 250 C, proving the feasibility of actuator-located switching of control power using optical signals transmitted by fibers. Assessments of the efficiency and technical merits were made for extension of this high-temperature technology to local conversion of optical power to electrical power and its control at levels useful for driving actuators. Optical power sources included in the comparisons were an infrared light-emitting diode, an injection laser diode, tungsten-halogen lamps and arc lamps. Optical-to-electrical power conversion was limited to photovoltaics located at the actuator. Impedance matching of the photovoltaic array to the load was considered over the full temperature range, -55 C to 260 C. Loss of photovoltaic efficiency at higher temperatures was taken into account. Serious losses in efficiency are: (1) in the optical source and the cooling which they may require in the assumed 125 C ambient, (2) in the decreased conversion efficiency of the gallium arsenide photovoltaic at 260 C, and (3) in impedance matching. Practical systems require improvements in these areas

Neuronal response in Alzheimer's and Parkinson's disease: the effect of toxic proteins on intracellular pathways

Accumulation of protein aggregates is the leading cause of cellular dysfunction in neurodegenerative disorders. Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease, Prion disease and motor disorders such as amyotrophic lateral sclerosis, present with a similar pattern of progressive neuronal death, nervous system deterioration and cognitive impairment. The common characteristic is an unusual misfolding of proteins which is believed to cause protein deposition and trigger degenerative signals in the neurons. A similar clinical presentation seen in many neurodegenerative disorders suggests the possibility of shared neuronal responses in different disorders. Despite the difference in core elements of deposits in each neurodegenerative disorder, the cascade of neuronal reactions such as activation of glycogen synthase kinase-3 beta, mitogen-activated protein kinases, cell cycle re-entry and oxidative stress leading to a progressive neurodegeneration are surprisingly similar. This review focuses on protein toxicity in two neurodegenerative diseases, AD and PD. We reviewed the activated mechanisms of neurotoxicity in response to misfolded beta-amyloid and α-synuclein, two major toxic proteins in AD and PD, leading to neuronal apoptosis. The interaction between the proteins in producing an overlapping pathological pattern will be also discussed.Shohreh Majd, John H. Power and Hugh J.M. Grantha

Simulator study of the low-speed handling qualities of a supersonic cruise arrow-wing transport configuration during approach and landing

A fixed-based simulator study was conducted to determine the low-speed flight characteristics of an advanced supersonic cruise transport having an arrow wing, a horizontal tail, and four dry turbojets with variable geometry turbines. The primary piloting task was the approach and landing. The statically unstable (longitudinally) subject configuration has unacceptable low-speed handling qualities with no augmentation. Therefore, a hardened stability augmentation system is required to achieve acceptable handling qualities, should the normal operational stability and control augmentation system fail. In order to achieve satisfactory handling qualities, considerable augmentation was required

Autonomous Satellite Recovery Vehicle (ASRV)

Abstract Embry-Riddle Future Space Explorers and Developers (ERFSEDS) will be attending a rocket competition in Utah this coming June, and they will receive extra points for the competition if they have a research project (not built by their club), inside of their rocket. In collaboration with ERFSEDS, the Society 4 S.P.A.C.E. team would like to send a small satellite attached to a quad-copter as the research project (payload) for ERFSEDS rocket. This rocket will reach an altitude of 10,000 to 20,000 feet. The quad-copters objective will be to collect atmospheric data as it descends. The plan is to create a new chassis for the quad-copters electronic components and arms that will allow the quad-copter to fold its arms inwards to meet the required space constraints. After launching the rocket, the quad-copter/satellite will be deployed at the maximum altitude and begin collecting data once jettisoned from the rocket. Once reaching 1,000 feet the quad-copter will be programmed to deploy a parachute. Once it has reached a safe velocity, the engines will engage at around 400 feet (the maximum altitude for any civil autonomous or r/c vehicle) and the quad-copter will autonomously navigate to a prearranged location. Flight planning will be done using the open source application Mission Planner. In addition to the critical components of the quad-copter, our design will integrate a number of other data collecting sub-systems currently being used in the weather balloon project designed by the Society 4 S.P.A.C.E. team. These sensors will be able to collect pressure, temperature, humidity, wind, and video. This project will provide it’s user with a better understanding of rocket propulsion systems, UAVs in high altitude/velocity, and the effect of launch on the payload. The A.S.R.V. will also drastically improve the data retrieval process, because it will bring the data directly to the user so the user does not have to search for it