共查询到20条相似文献,搜索用时 46 毫秒
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文章从实验研究、流行病学调查以及应激反应的理论等方面对噪声引起的心血管功能变化进行了简要的回顾与讨论.对动物和人的研究表明,在长期噪声暴露条件下产生了心、脑血管的功能调节障碍,出现脑血管和冠状血管收缩、脑的血流量减少和心肌缺血.噪声作为一种应激源还会引起各种与应激有关的激素增高,从而出现一系列全身反应,特别是心血管系统的反应.根据流行病学调查资料,获得了具有说服力的证据,在长期噪声暴露的人群中,心血管疾病的发病率均明显升高(包括高血压、心律不齐、心肌缺血、病理性心脏变形及眼底血管硬化等).以上研究提示,噪声与心血管疾病的发生具有因果关系. 相似文献
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对汽车在使用空调时由空调压缩机引起的两种内噪进行了研究,得到如下结论:(1)在发动机转速为4 750 rpm左右时出现的轰鸣噪声,是由于压缩机支架总成模态频率与发动机二阶振动频率共振引起的;(2)怠速时的拍频声是由于发动机与空调压缩机的传动比不合理造成的拍频现象。 相似文献
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通风空调系统辐射噪声是船舶舱室内最主要的噪声源,吸声处理是降低舱室噪声的一种有效途径。为考察吸声处理对降低舱室噪声的效果,建立通风空调管路噪声向船舶舱内辐射的有限元法数值预报模型。以实测的管口声压为噪声源,研究舱室壁面及通风管路吸声对舱室降噪效果的影响,进而用于指导和改进船舶舱室的声学设计。对通风空调系统改变后的舱室噪声进行预报,并针对较高的噪声进行声学设计,使舱室噪声问题得到解决。 相似文献
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在机场航班量大幅增加和机场扩建的同时,机场航空噪声问题越来越突出.传统的评价方法是参照国家标准,根据实测值进行评价.考虑机场航空噪声对居民影响的客观条件和主观反应,将它们作为评价因素,建立多级模糊综合评价模型,从而全面反映机场航空噪声对机场周围居民的实际影响程度,为机场航空噪声的评价提供新思路. 相似文献
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M. V. Tret'yakov 《Journal of Engineering Physics and Thermophysics》1992,63(2):771-774
The influence of external noise with nonzero correlation time (colored noise) on the combustion of a single particle is investigated. An equation for the steady-state thermal regimes of the reaction is derived. Spontaneous ignition of a particle is considered.A. M. Gor'kii Ural State University, Ekaterinburg. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 2, pp. 60, August, 1992. 相似文献
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Yu. V. Mishchenko 《Measurement Techniques》1995,38(8):884-887
The influence of noise in the optical and electronic channels of laser interference refractometers is subjected to a comparative analysis for several of the best-known methods used to measure the fractional part of an interference order.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 26–27, August, 1995. 相似文献
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Yu. V. Mishchenko 《Measurement Techniques》1996,39(3):300-306
The influence of noise on the resultant error probabilities in the detection of integral interference orders by various methods
of the kind most frequently used in laser refractometry is investigated.
Translated from Izmeritel'naya Tekhnika, No. 3, pp. 46–49, March, 1996. 相似文献
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Abstract A filtering algorithm which takes the measured Radon transform of the Wigner function of a quantum signal with thermal noise and produces the Wigner function of the corresponding ‘clean’ (noiseless) signal, is proposed. The general method is exemplified for number eigenstates with thermal noise and also for Schrödinger cats with thermal noise. 相似文献
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The cross-track profile of media noise is measured on a precision spinstand for oriented and nonoriented media. These data are correlated with magnetic force microscopy (MFM) images to determine the location of track-edge noise with high spatial resolution. A significant component of track-edge noise is located in a narrow band at the edge of bits recorded in opposition to the previously saturation-erased direction. This reverse erase-edge noise (REEN) increases as orientation ratio increases. The magnitude and distribution of REEN is consistent with a reverse-dc-erase mechanism. δM data indicate a greater influence of magnetostatic and/or exchange coupling for the oriented media. Together with larger on-track reverse-dc-erase noise and higher supralinear transition noise, these results suggest enhanced collective magnetization reversal for the oriented media relative to the nonoriented media. MFM images also reveal the presence of narrow magnetic-dipolar strips at the track edges. These dipolar strips are generated by cross-track components of the head field. The track-edge dipole moment decreases as orientation ratio increases due to preferential alignment of easy axes along the down-track direction. These dipoles contribute to base line shift and are not a significant source of media noise 相似文献