预先暴露低强度噪声对噪声损伤听力保护作用的观察

强噪声暴露可致听力损伤，产生暂时性或永久性听阈偏移。听力损伤程度除和噪声暴露参数有关外，还和听觉系统本身的生理和代谢状态有关［１］。实验证实，外毛细胞在声刺激后有类似耳肌收缩样作用［２］，但这种收缩作用对听力的生物效应还不清楚。低强度无损害性噪声暴露对后来的强声刺激是否有保护作用，国内尚未见有报导。本实验以豚鼠为实验动物，预先暴露低剂量安全噪声，随后暴露能产生听觉损害的强噪声，观察前者对后者的听力损伤有无保护作用。     

利用声暴露级对交通噪声主要因素进行探讨

利用声暴露级对交通噪声主要因素进行探讨胡跃平，蒋凤萍，唐秋霞（常州市环境监测站）近年来，随着国民经济的高速发展，机动车的急剧增加，致使交通噪声成为大部分城市环境质量各要素中较差的一个。因此，有必要对交通噪声主要影响因素进行剖析，消除一些认识上的偏差，...     

强噪声暴露后豚鼠听力和血清某些生化指标的变化

５３只白色短毛雄性豚鼠体重３００～４４０ｇ，随机分为６组，每组６～１０只。噪声暴露组和对照组各为３组。暴露噪声频谱是中心频率１ｋＨｚ、带宽１００Ｈｚ的狭带。噪声强度为１２６±１．５ｄＢＳＰＬ。暴露时间３ｈ／ｄ，连续１０天。噪声由Ｂ＆Ｋ１０２７纯音无规发生器产生，经ＪＹ前级增音和４００Ｗ功放后由扬声器组发出。声强由Ｂ＆Ｋ４１４５电容传声器、Ｂ＆Ｋ２６１５阴极输出器及Ｂ＆Ｋ２１０７频率分析仪监测，测量系统经Ｂ＆Ｋ２２３０声级校准器校准。噪声停止后当天（１～３ｈ）、３天（６９～７２ｈ）和９天，分别测定…     

三通道喷嘴雾化过程噪声性能的实验研究

研究了影响三通道喷嘴噪声声级的相关因素。实验研究结果表明,总气体流量一定时,一通道气体流量分率的变化,可导致噪声15dB左右的变化。同时,水量加入引起的雾化,改变了喷嘴噪声产生的机理。二通道水量在一定范围内可以消减噪声,范围之外,水量增加引起噪声变大。一、三通道气体流量的增大皆导致了噪声的单调增大。     

导弹脉冲噪声对听觉器官的损伤

新型导弹的装备虽大大加强了舰艇部队的作战能力，但导弹发射时所产生的强脉冲噪声将严重威胁有关舱室和战位人员的安全。在某型导弹实艇发射试验中，我们进行了脉冲噪声的测试和动物试验，较详细地观察了脉冲噪声对听觉器官的损伤，并根据人与豚鼠耐受性的差异，对有关舱室和战位人员的安全性作出评价。     

人与豚鼠对脉冲噪声听觉损伤的比较

本文从定性和定量方面分析了人与豚鼠对脉冲噪声听觉损伤的关系。研究的结论是,人听觉器官对脉冲噪声的耐受性较豚鼠为高,豚鼠听觉器官的轻伤范围对人来说是安全的。     

环境背景噪声对飞机噪声监测结果的影响

为研究在飞机噪声监测中背景噪声客观上无法满足标准要求时的数据有效性问题,选择在低噪声环境,距机场不同距离的位置测得基本不受背景噪声影响的飞机噪声数据,在上述数据的基础上叠加模拟的背景噪声,以分析背景噪声对监测结果的影响,分析表明：随着背景噪声的增加,飞机可感觉噪声级随着之增大;且背景噪声越高,增幅越大;当飞机最大等声级大于背景噪声15 dB以上时,增幅趋于稳定。进一步分析表明：造成可感觉噪声级变大的原因主要是飞机持续时间变长。基于上述结论,在监测中,若飞机最大声级与背景噪声的差值大于15 dB时,监测结果仍可较真实的反映测点受飞机噪声的影响情况;若小于15 dB,则监测结果与不受背景噪声影响时相比,偏大较多。当飞机最大声级仅高于背景噪声10 dB时：对于特大型机场,监测点位于1～2 声环境达标类区时,其飞机噪声达标判定会受 到干扰;对于大型机场,监测点位于2 类声环境达标区时,其飞机噪声达标判定会受到干扰;而对于中型机场,则其达标判定基本不受干扰。当飞机最大声级高于背景噪声15 dB时,其达标判定也基本不受干扰。     

脉冲噪声对听力的影响

脉冲噪声是不同于连续噪声的一种特殊噪声.它不仅存在于军事领域,工业部门也较多见,爆破,冲床、铆工、锻工,锤工和钻工等工种都有脉冲噪声源.据资料,美国有460万人在高强度脉冲噪声下工作,估计我国直接或间接暴露该噪声环境的人员远超出此数值.值得注意的是,在不少连续噪声环境中,混杂着脉冲噪声成份,往往被人们忽视.和连续噪声相比,脉冲噪声对听力的损害在性质和程度上都不同,甚至吏为严重.因此,研究脉冲噪声及其对听力的影响是噪声领域中一个重要课题.     

脉冲噪声压力峰值与豚鼠听觉损伤的关系

本文研究了脉冲噪声暴露后豚鼠的听觉损伤。文中参照文献资料讨论了人与豚鼠对脉冲噪声的听觉安全界线。     

气象条件对噪声自动监测的影响

气象条件对噪声自动监测数据有效性的影响究竟有多大,噪声自动监测是否要同步进行气象监测,这些都需要进行深入的分析研究。结合大量监测数据及相关资料,重点对环境噪声监测中声级-风速相关性进行分析,提出进行环境噪声自动监测时,为保证监测数据的科学性和准确性,应同步进行风速测量,结合风速监测数据对噪声监测数据进行有效取舍。     

An investigation of noise factor effects in parameter design

Parameter design aims to determine nominal values of a set of design parameters so as to minimize variability in one or more key performance measures, in the presence of uncertainties in the design parameters, whilst maintaining the required nominal (design point) performance and the overall design concept. A theoretical analysis of some aspects of parameter design and of some related approximate methods is carried out and the results studied with the aim of determining the effect of changes in the magnitudes of the uncertainties in the design parameters on the resulting values of nominal parameter values in the optimum design. It is shown that there is reason to expect that, allowing for the effects of constraints, a given parameter design would be robust against overall changes, by a constant factor, in the parameter uncertainties but not in the presence of changes in individual parameter uncertainties, or by numerous such changes when the change factor varies between individual parameters. Some numerical results are obtained for problems in beam design and are shown to support the above assertions. The results imply that nominal values in a previously determined robust design may continue to be valid when parameter tolerances change, provided such changes are by the same factor for all free design parameters, i.e. those not fixed on a constraint boundary. Copyright © 2002 John Wiley & Sons, Ltd.     

An investigation on diffusion bonding of aluminum to copper using equal channel angular extrusion process

A new method for production of bimetallic rods, utilizing the equal channel angular extrusion (ECAE) process has been introduced before by previous researchers, but no attempt has been made to assess the effect of different temperatures and holding times in order to achieve a diffusional bond between the mating surfaces. In present research copper sheathed aluminum rods have been ECAEed at room temperature and subsequently held at a constant ECAE pressure, at different temperatures and holding times to produce a diffusional bond between the copper sheath and the aluminum core. The bonding quality of the joints was examined by shear strength test and a sound bonding interface was achieved. Based on the results, a bonding temperature of 200 °C and holding time of 60-80 min yielded the highest shear strength value.     

短时能量分析及人耳的主观听觉在船舶辐射噪声特征提取中的研究

文章提出了利用短时能量分析与人的主观听觉相结合的方法进行船舶辐射噪声特征提取。通过对实际船舶辐射噪声信号的分析，结果表明将船舶辐射噪声的人耳听测特征与信号处理后的数字特征相结合，可以达到对船舶辐射噪声特征提取的目的。     

An investigation of high-frequency bias-induced tape noise

Bias-induced tape noise remains a major limitation of the SNR in audio magnetic tape recording systems. Defined as the increment in system noise incurred when the bias oscillator is turned on, the noise can originate from a number of different causes; namely, bias oscillator harmonic distortion, magnetized heads, the earth's magnetic field, and an intrinsic noise source. The latter noise source is our primary concern here. Such record system parameters as head-to-tape spacing, gap length, bias current, and bias frequency were investigated with regard to their influence on this intrinsic bias noise source. Two models of the mechanism of intrinsic bias noise are examined. The first, the "amplitude modulation model." proposes that bias noise is generated by amplitude modulation of the recorded bias signal by the physical and magnetic variations of the head-tape system. In this model, bias noise is merely the lower AM sidebands of the recorded bias signal. The second model relates bias noise to the interaction fields in erased tape. This model proposes that these fields behave similarly to normal recording fields and can be "re-recorded" on the tape at an enhanced level. The two proposed mechanisms are examined in the light of the experimental data. The amplitude modulation model is shown to agree with all the observed data with the exception of the existence of bias noise at bias wavelengths smaller than the particle size. The second model, which does not incorporate a wavelength dependency of bias noise, is in qualitative agreement with the observed data. Methods are discussed for reducing the bias noise without materially affecting the system performance.     

An investigation of heat exchange in the human organism on exposure to internal heat

The thermal field of a person exposed to artificial heat is investigated. A variation in the blood flow as the temperature inside the body increases is calculated by solving the inverse problem of heat conductivity.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 52, No. 4, pp. 654–659, April, 1987.     

An experimental investigation of wave energy trapping

The type of motions under consideration are surface waves over shallow-water regions bordered by an area of deeper water (although we shall consider this deeper water sufficiently shallow, compared with wavelength, to be amenable to shallow-water theory). It is now well known that oscillations of this type can be trapped by the bottom contours. We discuss two different bottom topographies and compare the theoretical and experimental results. In both cases good agreement is reached.     

An investigation on rotatory bending fretting fatigue damage of railway axles

Fretting damage failure analysis of a Chinese carbon railway axle RD₂ was carried out. The wheel hub was in situ cut to expose the damaged surface of the wheel seat to avoid additional damage. A small‐scale axle test rig was developed, and simulation tests were performed at different rotator speeds of 1800 and 2100 rpm. The wear mechanism of fretting damage areas was a combination of abrasive wear, oxidative wear and delamination. The fracture surfaces exhibited characterization of multisource and step‐profile. The fretting fatigue crack initiated at the subsurface and propagated along an inclined angle at the first stage. The fretting damage at the higher speed was more severe compared with the lower speed, which lead to a relatively shorter fatigue life. The damage morphologies of the axle in the simulation tests were in good agreement with that observed in the failure analysis on real axle.     

An investigation on the effects of equal channel angular pressing on the mixed‐mode fracture toughness and mechanical properties of 6063 aluminium alloy

In this study, effects of equal channel angular pressing (ECAP) on the mixed‐mode fracture toughness of Al‐6063 were investigated. The ECAP process continued up to 5 passes without failure. Grain refinement was obvious after 5 passes of the ECAP process. The average grain size reduced from 45μm to less than 1μm, and textural studies shows aligning the grains in known directions. After 4 passes, yield and ultimate strengths increase respectively from 100 and 209 MPa to 300 and 375 MPa and reduction in elongation was also observed. The microhardness improved after the process. The fracture toughness for different orientations was measured. For pure mode I (opening mode), its value decreased after the first pass from 18.4 to 15.71  ; however, it increased to about 18.8  after the fifth pass. For mixed‐mode loading condition, different orientations were investigated. The results revealed different fracture toughness reductions after the first passes of the process for specimens with different orientations. The fracture surfaces were studied by using scanning electron microscope, and refined equiaxed dimples were observed after the ECAP process.     

Crash protectiveness to occupant injury and vehicle damage: An investigation on major car brands

This study sets out to investigate vehicles’ crash protectiveness on occupant injury and vehicle damage, which can be deemed as an extension of the traditional crash worthiness. A Bayesian bivariate hierarchical ordered logistic (BVHOL) model is developed to estimate the occupant protectiveness (OP) and vehicle protectiveness (VP) of 23 major car brands in Florida, with considering vehicles’ crash aggressivity and controlling external factors. The proposed model not only takes over the strength of the existing hierarchical ordered logistic (HOL) model, i.e. specifying the order characteristics of crash outcomes and cross-crash heterogeneities, but also accounts for the correlation between the two crash responses, driver injury and vehicle damage. A total of 7335 two-vehicle-crash records with 14,670 cars involved in Florida are used for the investigation. From the estimation results, it's found that most of the luxury cars such as Cadillac, Volvo and Lexus possess excellent OP and VP while some brands such as KIA and Saturn perform very badly in both aspects. The ranks of the estimated safety performance indices are even compared to the counterparts in Huang et al. study [Huang, H., Hu, S., Abdel-Aty, M., 2014. Indexing crash worthiness and crash aggressivity by major car brands. Safety Science 62, 339–347]. The results show that the rank of occupant protectiveness index (OPI) is relatively coherent with that of crash worthiness index, but the ranks of crash aggressivity index in both studies is more different from each other. Meanwhile, a great discrepancy between the OPI rank and that of vehicle protectiveness index is found. What's more, the results of control variables and hyper-parameters estimation as well as comparison to HOL models with separate or identical threshold errors, demonstrate the validity and advancement of the proposed model and the robustness of the estimated OP and VP.