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81.
S Jones 《Canadian Metallurgical Quarterly》1997,12(12):28-31
A new method of impulse magnetic therapy was studied in the treatment of neurologic complications of osteochondrosis and deforming spondylarthrosis in 225 patients with neurologic manifestations of pathology in cervical or sacral parts of spinal column. To assess the results obtained, EMG, thermography and determination of the levels of blood plasma lipid peroxidation were used. 相似文献
82.
Fatigue properties of cast aluminum components are controlled by maximum defect size in the material. The larger the maximum
defect size, the lower the fatigue strength and life. In the presence of casting defects, crack initiation can be ignored
and fatigue life is mainly spent in crack propagation. Therefore, fatigue life of aluminum castings can be predicted by long
or short crack growth models. The main problem is defining a starting defect size from readily available data, such as twodimensional
(2-D) pore size measurements on metallographic sections. In this article, an extremevalue statistics (EVS) method was used
to estimate the maximum defect size in 319 castings from conventional metallographic data. The maximum defect size predicted
by EVS agrees quite well with the initiation defect sizes measured from fracture surfaces, and the predicted fatigue life
is in reasonable agreement with the experimental data. 相似文献
83.
The complete crystallographic orientation dependence of the growth rate for GaAs low pressure organometallic vapor phase epitaxy
(LPOMVPE) is determined using a previously described semi-empirical model. A set of LPOMVPE growth rate polar diagrams is
presented for reactor temperatures near 550°C as well as near 700°C. Also, the variation of the growth rate polar diagrams
as a function of process variables is given. The experimental data utilized in the semiempirical model was attained using
a typical horizontal reactor LPOMVPE system and typical LPOMVPE process parameters. 相似文献
84.
85.
A new type of fiber laser modelocking is examined where a phase modulator is driven asynchronously with respect to a harmonic of the roundtrip cavity frequency. An asynchronous drive is able to produce high repetition rate (>1 GHz) soliton pulses that are shorter than the classic, active modelocking pulse width limit. It is shown that with a proper choice of fiber parameters, noise cleanup and soliton pulse shaping can be obtained using filtering and asynchronous phase modulation. Limits of asynchronous detuning are derived and a comparison with the parameters ranges for synchronous phase modulation is also presented 相似文献
86.
87.
James A. Cutts Kerry T. Nock Jack A. Jones Guillermo Rodriguez J. Balaram 《Autonomous Robots》1995,2(4):261-282
Planetary aerobots are a new type of telerobotic science platform that can fly and navigate in a dynamic 3-dimensional atmospheric environment, thus enabling the global in situ exploration of planetary atmospheres and surfaces. Aerobots are enabled by a new concept in planetary balloon altitude control, developed at JPL, which employs reversible-fluid changes to permit repeated excursions in altitude. The essential physics and thermodynamics ofreversible-fluid altitude control have been demonstrated in a series of altitude-control experiments conducted in the Earth's atmosphere, which are described. Aerobot altitude-control technology will be important in the exploration of seven planets and satellites in our solar system. Three of these objects—Venus, Mars, and the Saturnian satellite Titan—have accessible solid surfaces and atmospheres dominated by the dense gases nitrogen or carbon dioxide. They will be explored with aerobots using helium or hydrogen as their primary means of buoyancy. The other four planets—Jupiter, Saturn, Uranus, and Neptune—have deep atmospheres that are predominantly hydrogen. It may be possible to explore these atmospheres with aerobots inflated with atmospheric gas that is then radiatively heated from the hotter gaseous depths below. To fulfill their potential, aerobots to explore the planets will need autonomous state estimators to guide their observations and provide information to the altitude-control systems. The techniques of acquiring these data remotely are outlined. Aerobots will also use on board altitude control and navigation systems to execute complex flight paths including descent to the surface and exploiting differential wind velocities to access different latitude belts. Approaches to control of these systems are examined. The application of aerobots to Venus exploration is explored in some detail: The most ambitious mission described, the Venus Flyer Robot (VFR), would have the capability to make repeated short excursions to the high-temperature surface environment of Venus to acquire data and then return to the Earth-like upper atmosphere to communicate and recool its electronic systems. Finally a Planetary Aerobot Testbed is discussed which will conduct Earth atmospheric flights to validate autonomous-state-estimator techniques and flight-path-control techniques needed for future planetary missions. 相似文献
88.
This article identifies the key issues involved in the debate about affirmative action. The June 2003 Supreme Court decisions allowing consideration of race to ensure that there is a "critical mass" of African American, Latino/Latina, and Native American applicants to higher education are addressed. Social psychologists have identified key myths and provided clarifications about the need for and consequences of strategies used to promote equal opportunity for persons of color and women. A brief history of affirmative action and of the problems it was designed to solve is provided. The accomplishments, benefits, and compelling interest of diversity and affirmative action are described, as well as the concerns and counterpoints. The lack of a substantial applicant pool in psychology hinders progress toward diversity. Alternative strategies for remedying this lack beyond affirmative admissions policies in psychology are briefly discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
90.
An overview of the most important older and newer results regarding the relationship between violent and criminal behavior on the one hand and schizophrenic illness on the other hand is presented. Four different methods are available to study this relationship: (i) study of the prevalence of mental illness in criminal/violent populations; (ii) study of criminality/violence rate in samples of psychiatric patients; (iii) study of criminality/violence in community samples comparing mental patients with non-patient community residents; and (iv) study of criminality/violence in birth cohorts prospectively. All these methods have been used; but samples composed of schizophrenic patients exclusively were only exceptionally studied. The results indicate that there is a modest but significant relationship between schizophrenia and violence and crime which persists even after controlling for demographic and socio-economic variables. The probability of schizophrenic patients to be criminal or violent depends on the acuity of their illness and is increased by their use of psychoactive substances. Generally, however, violent and criminal acts directly attributable to mental illness account only for a very small proportion of such acts in the society. 相似文献