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171.
Hartmut Bartelt Wolfgang Ecke Reinhardt Willsch Jens Kobelke Michael Kautz Sven Brueckner Manfred Rothhardt 《中国电子科技》2008,6(4):429-433
This paper reports fiber Bragg gratings (FBGs) inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot interferometer. The responses of such FBGs to temper- ature, strain, bending, and transverse-loading were systematically investigated. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and transverse-loading. The bending and transverse- loading properties of the FBGs are sensitive to the fiber orientations. 相似文献
172.
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174.
Hartmut Irle Christian Rosenthal Helmut Strasser 《International Journal of Industrial Ergonomics》1999,23(5-6):573-584
Valuable recommendations for the choice, utilization, care, and maintenance, and for the measurement of sound attenuation of hearing-protective devices have been laid down in international standards. Yet, by considering the wearing time of a hearing protector, the standard DIN EN 458 assumes a scarcely understandable drastic reduction in the effective attenuation even when the device is not used for only a short time in a noise-filled area. A 30 dB sound attenuation of such a protective device would, e.g., decrease to 12 dB if it were unused for only 30 min of an 8 h shift. Thus, the actual influence of a shortened wearing time on the protection of earmuffs was tested in a laboratory study using audiometric measurements of the temporary threshold shift (TTS2) and its recovery after exposure to noise. For that purpose, the effectiveness of a hearing-protective device depending on the amount of time worn as prognosticated by DIN EN 458 was compared with the actual physiological effect of the earmuffs. Ten test subjects (Ss) participated in three test series (TS), each. In the first of the TS, the Ss were exposed to a sound pressure of 106 dB(A) for 1 h, during which the Ss wore noise-insulating earmuffs with an attenuation of 30 dB. The Ss were exposed to the same sound pressure in TS II; however, after 30 min, the earmuffs were removed for a duration of
min. Mathematically, this reduced the sound attenuation of the earmuffs to 12 dB, i.e., the average noise level over 1 h is 94 dB, which is equivalent to 85 dB(A) over 8 h. In order to evaluate the actual additional physiological cost of TS II, the Ss were exposed to 94 dB(A)/1 h without earmuffs in a third TS. This acoustic load, which is energy equivalent to the load in TS II, is also equivalent to 85 dB(A)/8 h. The results show that the continuous wearing of the earmuffs offers secure protection. However, the energetic approach and the levelling of differently structured noise loads according to the principle of energy equivalence leads to misconceiving results. The drastic reduction of the sound attenuation of the earmuffs predicted from the energetic point of view must be regarded as exaggerated. The TTS values show that TS II – which, according to the principle of energy-damage-equivalence, should result in the same effects as TS III – represents significantly less auditory fatigue. Thus, if the earmuffs are taken off briefly, a drastic reduction in the protection – as predicted in DIN EN 458 — does not result.
Relevance to industry
The results of this study demonstrate that the standards and regulations for noise rating do not correspond with the actual physiological facts and, therefore, can only be used in a very limited manner. Utilization of the principle of energy equivalence has proven problematic not only for rating noise. This principle also leads to an essential underestimation of the attenuation of hearing protectors when these devices are taken off for only a short time in a noise-filled area. 相似文献
175.
C. Hassel K. Blaum T. Day Goodacre H. Dorrer Ch. E. Düllmann K. Eberhardt S. Eliseev C. Enss P. Filianin A. Fäßler A. Fleischmann L. Gastaldo M. Goncharov D. Hengstler J. Jochum K. Johnston M. Keller S. Kempf T. Kieck U. Köster M. Krantz B. Marsh C. Mokry Yu. N. Novikov P. C. O. Ranitzsch S. Rothe A. Rischka J. Runke A. Saenz F. Schneider S. Scholl R. X. Schüssler F. Simkovic T. Stora P. Thörle-Pospiech A. Türler M. Veinhard M. Wegner K. Wendt K. Zuber 《Journal of Low Temperature Physics》2016,184(3-4):910-921
176.
177.
Eingegangen am 20.03.1996, in überarbeiteter Form am 17.02.1997 相似文献
178.
Antoine Tran Tan Joel Falcou Daniel Etiemble Hartmut Kaiser 《International journal of parallel programming》2016,44(3):449-465
Providing high level tools for parallel programming while sustaining a high level of performance has been a challenge that techniques like Domain Specific Embedded Languages try to solve. In previous works, we investigated the design of such a DSEL—NT\(^2\)—providing a Matlab -like syntax for parallel numerical computations inside a C++ library. In this paper, we show how NT\(^2\!\) has been redesigned for shared memory systems in an extensible and portable way. The new NT\(^2\!\) design relies on a tiered Parallel Skeleton system built using asynchronous task management and automatic compile-time taskification of user level code. We describe how this system can operate various shared memory runtimes and evaluate the design by using two benchmarks implementing linear algebra algorithms. 相似文献
179.
A new bifunctional coupling agent with an oxazinone and a lactamate group is synthesized. It is shown by means of model reactions that in the presence of aliphatic hydroxy compounds the reaction of the coupling agent is highly selective. At 220 °C, a conversion of the lactamate group of about 90% is observed under elimination of lactam. In a second reaction the oxazinone group is converted with an aliphatic amino compound. This high selectivity is utilized in the synthesis of segmented polyester/polyamide block copolymers by sequential conversion of the coupling agent with hydroxy‐terminated polyesters [poly(butylene terephthalate) (PBT) and polycaprolactone (PCL)] and amino‐terminated polyamide 12 (PA12) under the conditions of reactive extrusion. In the case of the PA12/PBT block copolymer, ductile behavior is observed, whereas the PA12/PCL block copolymer shows elastic properties. Both polymers are phase separated on the nanometer‐scale, as evidenced by AFM and SEM. The thermal behavior of the polymers is affected by the influence of the individual blocks.
180.
Darryl P. Butt Klaus S. Lackner Christopher H. Wendt Samuel D. Conzone Harriet Kung Yung-Cheng Lu Julie K. Bremser 《Journal of the American Ceramic Society》1996,79(7):1892-1898
The kinetics of simultaneous dehydroxylation and carbonation of precipitated Mg(OH)2 were studied using isothermal and nonisothermal thermogravimetric analyses. Specimens were analyzed using X-ray diffraction, transmission electron microscopy, and through measurements of the volume of carbon dioxide evolved in a subsequent reaction with hydrochloric acid. From 275° to 475°C, the kinetics of isothermal dehydroxylation in helium were best fit to a contracting-sphere model, yielding an activation energy of 146 kJ/mol, which was greater than values reported in the literature for isothermal dehydroxylation under vacuum (53–126 kJ/mol). The carbonation kinetics were complicated by the fact that dehydroxylation occurred simultaneously. The overall kinetics also could be fit to a contracting-sphere model, yielding a net activation energy of 304 kJ/mol. The most rapid carbonation kinetics occurred near 375°C. At this temperature, Mg(OH)2 underwent rapid dehydroxylation and subsequent phase transformation, whereas thermodynamics favored the formation of carbonate. During carbonation, MgCO3 precipitated on the surface of disrupted Mg(OH)2 crystals acting as a kinetic barrier to both the outward diffusion of H2 O and the inward diffusion of CO2 . 相似文献