On the applicability of integrated circuit technology to general aviation orientation estimation

The criteria of the significant value of the panel instruments used in general aviation were examined and kinematic equations were added for comparison. An instrument survey was performed to establish the present state of the art in linear and angular accelerometers, pressure transducers, and magnetometers. A very preliminary evaluation was done of the computers available for data evaluation and estimator mechanization. The mathematical model of a light twin aircraft employed in the evaluation was documented, the results of the sensor survey and the results of the design studies were presented

Aircraft digital control design methods

Variations in design methods for aircraft digital flight control are evaluated and compared. The methods fall into two categories; those where the design is done in the continuous domain (or s plane) and those where the design is done in the discrete domain (or z plane). Design method fidelity is evaluated by examining closed loop root movement and the frequency response of the discretely controlled continuous aircraft. It was found that all methods provided acceptable performance for sample rates greater than 10 cps except the uncompensated s plane design method which was acceptable above 20 cps. A design procedure based on optimal control methods was proposed that provided the best fidelity at very slow sample rates and required no design iterations for changing sample rates

Aircraft digital control design methods

Investigations were conducted in two main areas: the first area is control system design, and the goals were to define the limits of 'digitized S-Plane design techniques' vs. sample rate, to show the results of a 'direct digital design technique', and to compare the two methods; the second area was to evaluate the roughness of autopilot designs parametrically versus sample rate. Goals of the first area were addressed by (1) an analysis of a 2nd order example using both design methods, (2) a linear analysis of the complete 737 aircraft with an autoland obtained using the digitized S-plane technique, (3) linear analysis of a high frequency 737 approximation with the autoland from a direct digital design technique, and (4) development of a simulation for evaluation of the autopilots with disturbances and nonlinearities included. Roughness evaluation was studied by defining an experiment to be carried out on the Langley motion simulator and coordinated with analysis at Stanford

Proceedings of the Air Transportation Management Workshop

The Air Transportation Management (ATM) Workshop was held 31 Jan. - 1 Feb. 1995 at NASA Ames Research Center. The purpose of the workshop was to develop an initial understanding of user concerns and requirements for future ATM capabilities and to initiate discussions of alternative means and technologies for achieving more effective ATM capabilities. The topics for the sessions were as follows: viewpoints of future ATM capabilities, user requirements, lessons learned, and technologies for ATM. In addition, two panel sessions discussed priorities for ATM, and potential contributions of NASA to ATM. The proceedings contain transcriptions of all sessions

DC Cancellation As a Method of Generating a t^2 Response and of Solving the Radial Nonobservability Problem in a Concentric Free-Falling Two-Sphere Equivalence-Principle Experiment in a Drag-Free Satellite

This paper solves two major problems which have blocked a free-fall Equivalence-Principle (EP) in a satellite for 25 years: a semimajor-axis error between the two proof masses cannot be distinguished from an EP violation and the response to an EP violation only grows as t not t^2. Using the cancellation method described in this paper, the nonobservability problem can be suppressed and a t^2 response can be generated which lasts between 10^4 and 10^6 seconds depending on the cancellation accuracy. t^2 response times between 10^5 and 10^6 seconds are equivalent to a very tall (0.1 to 10 AU) drop tower with a constant gravitational field of 3/7 ge.Comment: 40 pages, 7 figures, Revision 3.0: Reviewer's suggested corrections for journal submissio

Unfertilized Xenopus Eggs Die by Bad-Dependent Apoptosis under the Control of Cdk1 and JNK

Ovulated eggs possess maternal apoptotic execution machinery that is inhibited for a limited time. The fertilized eggs switch off this time bomb whereas aged unfertilized eggs and parthenogenetically activated eggs fail to stop the timer and die. To investigate the nature of the molecular clock that triggers the egg decision of committing suicide, we introduce here Xenopus eggs as an in vivo system for studying the death of unfertilized eggs. We report that after ovulation, a number of eggs remains in the female body where they die by apoptosis. Similarly, ovulated unfertilized eggs recovered in the external medium die within 72 h. We showed that the death process depends on both cytochrome c release and caspase activation. The apoptotic machinery is turned on during meiotic maturation, before fertilization. The death pathway is independent of ERK but relies on activating Bad phosphorylation through the control of both kinases Cdk1 and JNK. In conclusion, the default fate of an unfertilized Xenopus egg is to die by a mitochondrial dependent apoptosis activated during meiotic maturation