8,658 research outputs found
Optimization of thermal systems with sensitive optics, electronics, and structures
A strategy was investigated by which thermal designers for spacecraft could devise an optimal thermal control system to maintain the required temperatures, temperature differences, changes in temperature, and changes in temperature differences for specified equipment and elements of the spacecraft's structure. Thermal control is to be maintained by the coating pattern chosen for the external surfaces and heaters chosen to supplement the coatings. The approach is to minimize the thermal control power, thereby minimizing the weight of the thermal control system. Because there are so many complex computations involved in determining the optimal coating design a computerized approach was contemplated. An optimization strategy including all the elements considered by the thermal designer for use in the early stages of design, where impact on the mission is greatest, and a plan for implementing the strategy were successfully developed. How the optimization process may be used to optimize the design of the Space Telescope as a test case is demonstrated
Error control for reliable digital data transmission and storage systems
A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K-bit DRAM's are organized in 32Kx8 bit-bytes. Byte oriented codes such as Reed Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. In this paper we present some special decoding techniques for extended single-and-double-error-correcting RS codes which are capable of high speed operation. These techniques are designed to find the error locations and the error values directly from the syndrome without having to use the iterative alorithm to find the error locator polynomial. Two codes are considered: (1) a d sub min = 4 single-byte-error-correcting (SBEC), double-byte-error-detecting (DBED) RS code; and (2) a d sub min = 6 double-byte-error-correcting (DBEC), triple-byte-error-detecting (TBED) RS code
Towards a Phenomenology of Objects: Husserl and the Life-World
In this paper, I explore Edmund Husserl's account of the life-world for evidence that he posits it as the living flesh of the transcendental ego and thus as our primordial object-relation. In so doing, I attempt to rehabilitate and defend Husserl's notion of transcendental subjectivity, of the a priori, by noting how one's embodiment in many concrete experiences calls for and bears witness to this transcendental foundation of itself. After developing my reading of Husserl's account of the life-world, I then turn to the phenomenological psychology of John Russon in his book Human Experience to show how Husserl's life-world as the primordial object-relation opens us onto a very concrete vision of intersubjectivity
The National Solar Energy Research Institute: Function, Organization, and the First Six Months
The role of the Solar Energy Research Institute (SERI) in the national solar program is discussed. A brief history of developments leading to the formation of SERI is included. Functional responsibilities, organization and the current plans for staff and facilities growth are addressed
COSMOS 2044: Lung morphology study, experiment K-7-28
Researchers examined the effect of microgravity during spaceflight on lung tissue. The ultrastructure of the left lungs of 5 Czechoslovakian Wister rats flown on the 13 day, 19+ hour Cosmos 2044 mission was examined and compared to 5 vivarium and 5 synchronous controls at 1-g conditions, and 5 rats exposed to 14 days of tail suspension. Pulmonary hemorrage and alveolar adema of unknown origin occurred to a greater extent in the flight, tail-suspended, and synchronous control animals, and in the dorsal regions of the lung when compared with the vivarium controls. The cause of these changes, which are possibly due to an increase in pulmonary vascular pressure, requires further investigation
Study of a colliding laser-produced plasma by analysis of time and space-resolved image spectra
The interaction of two counter-propagating laser-produced plasmas was studied using simultaneous
imaging and spectroscopic techniques. Spectrally-filtered time-gated ICCD imaging was used
to obtain information about the spatial dynamics and temporal evolution of the collision process.
While, time-resolved imaging spectroscopy was used to determine the spatial and temporal distributions
of electron temperature and density within the interaction region. We examine specifically
the interaction of plasmas whose parameters match those typically used in pulsed laser deposition
of thin films. These low temperature plasmas are highly collisional leading to the creation of a
pronounced stagnation layer in the interaction region
Methods of designing cascade blades with prescribed velocity distributions in compressible potential flows
By use of the assumption that the pres=sure-vohm.erelation is linear, a solution to the problem of designing a cascadefor a given turning and with.a prescribed relocity distribution along the blade in a potentialows of mwnprewibkand incompressiblecant bladeshape. Numerical examples are included
Method of designing airfoils with prescribed velocity distributions in compressible potential flows
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