In particular, flows through the throttling or pressure valve, cross-sectional mutation or rapid-bend of the elbow pipe when the fluid turbulence with these obstacles through the part of the interaction of eddy-current noise, the sound power level vs.
尤其流经节流或降压阀门、截面突变的管道或急骤拐弯的弯头时，湍流与这些阻碍流体通过的部分相互作用产生涡流噪声，其声功率级随流速的变化关系可表示为：△Lw=60lg，若管路设计不当还可以产生空化噪声； 2、再说阀门，带有节流或限压作用的阀门，是液体传输管道中影响最大的噪声源。
Minimum flow rate, also known as automatic recirculation valve return valve for centrifugal pump minimum flow of auto recycling, installed in the pump discharge, the pump provides the most economical and reliable protection, the pump can run at low load when a small volume of medium recycling to ensure the pump's minimum flow to maintain the stable operation of the pump, to prevent the centrifugal pump at low load Plug Valves as overheating, noise, vibration and damage.
最小流量回流阀又称自动再循环阀，用于离心泵最小流量的自动再循环，安装于泵的出口，为离心泵提供最经济、最可靠的保护，调节阀能使泵在低负荷运行时有小量介质再循环，保证泵的最小流量，维持泵的稳定运行，防止离心泵在低负载下由于过热、噪音、振动而造成损坏。
Air velocity relationship could be is expressed as:△ Lw = 60lg, if the pipes are poorly designed can produce cavitation noise; 2, again the valve, with the role of throttling or pressure limiting valves, liquid transmission pipelines that affect the largest noise source.
当管道内流体流速足够时，若阀门部分关闭，则在阀门入口处形成大面积扼流，在扼流区域液体流速提高而内部静压降低，当流速大于或等于介质的临界速度时，静压低于或等于介质的蒸发压力，则在流体中形成气泡。
The information includes combustion, valve-open and valve-close information. But this signal also contains interfering noise, like exhaust noise and other noise eradiated from the other part of the diesel engine, and the frequency composition of useful signal and interfering noise are largely overlapped in the frequency band under 20 KHz.
但是提取的缸盖噪声信号中也含有柴油机工作时产生的排气噪声和机体其它部位辐射噪声等干扰信号，且干扰信号与有用信号的频率成分在20 kHz以下的频带内重叠在一起。
Based on a series of signal process and noise source identification techniques, especially the major noise source identification methods, such as expurgation method, sound intensity analysis, spectrum analysis vibro-acoustic correlation analysis and so on, the pass-by noise control of SC7080A and SC6360B are studied in detail. By the roadway and dais experiments, the major noise and radiating parts are identified and some economical controlling methods are made. For the SC7080A, to control the emissing noise from the intake and shell vibration of air cleaner, a intake muffler is installed between the air cleaner and intake valve. Based on the theory of Helmholtz resonator, One three-parallel-connected resonant silencer is designed and trial-manufactured. For the SC6360B, the attenuation performance of exhaust muffler in high frequency region is improved. To reduce the vibration noise of shell part, the structure of oil sump tank, exhaust manifold shield and exhaust manifold shield are analyzed and improved. At the same time, some measures, such as sound absorption, sound insulation, are taken to reduce the noise of engine surface emissivity and a sound shield is designed.
本文首先综述了目前国内外汽车加速噪声控制的现状、主要方法和技术措施，在此基础上，结合SC7080A和SC6350B汽车的车外加速噪声水平及现状，综合运用分别运行法、声强法、频谱分析法、声振相干函数法等现代噪声源识别方法，对SC7080A和SC6360B汽车进行了准确详细的车外加速噪声源识别并提出了经济可行的控制方案，针对SC7080A，主要在空气滤清器和进气阀门之间的进气管道上加装进气消声器，抑制空气滤清器壳体表面和进气口两处的噪声辐射，根据Helmholtz共振腔原理设计了三腔并联旁支型共振消声器，并进行了工程化设计和试制；针对SC6360B，主要改善了排气消声器在高频段的消声性能，对罩壳类零件进行了结构改进，降低了其表面噪声的辐射，并对发动机舱进行了吸声、隔声处理，设计了发动机隔声罩。
In this paper the recommended limit value of audible noise in the residential area near ±800kV converter station and that in the field of ±800kV converter station are given; the noise distribution in converter station, where the layout of valve hall and converter transformer are in single-line form or in face-to-face form, is calculated and analyzed; the effects of noise reduction measures, namely installing sound barrier near the main sound sources such as converter transformers or installing sound proof housing around the converter transformer, are analyzed.
给出了±800 kV换流站附近居住区和换流站厂界噪声的建议限值；对换流站阀厅和换流变压器按一字形和面对面2种方式布置的换流站噪声分布进行了计算分析；对在换流变压器等主要声源附近加装声屏障和换流变压器加装隔音罩的降噪效果进行了分析。
Analysis results show that the noise environment outside the ±800kV converter station can be effectively improved by use of the layout of valve hall and converter transformer in face-to-face form; when a certain noise reduction measures are adopted, the sound pressure level at the position that is 20m apart from the wall of converter station can satisfy the nightly standard requirement of the area in second class, i. e., not exceeding 50dB.
结果表明，±800 kV换流站的阀厅和换流变压器按面对面布置可有效改善站外噪声环境，采取一定降噪措施后，可使围墙外20m的声压级满足II类夜间标准要求不超过50 dB
Main features of this switch: The working range of the switch is from －55℃～＋125℃ degrees; The switch will be put into work at the zero crossover of the voltage without arc or mechanical noise; Based on Digital Thermometer/Thermostat DS1620 and AT89C51, the system is more flexible and has a wide application ranges; The valve value of the temperature can be modified by the user; The switch will produce no EMI to the environment.
本开关的工作特点：开关工作的温度范围在－55℃～＋125℃之间；开关工作时无任何机械碰撞噪声，无电弧，零电压接通；MCS-51与新型温度传感器组成的系统，功能及灵活性大为增强，温度上、下限可由用户实时设定；对外界无或很小的电磁干扰。
Base on this, the sample of the cam is made and noise level of the valve train system before and after the optimization is tested.
在此基础上，制作了凸轮样件并对优化前后配气机构进行声功率测试试验。
The valve petal uses the spring to load, its quick closedown can effective reduce the hammer pressure, the sealing property is good, the closure does not have the noise.
阀瓣采用弹簧加载，其快速关闭能有效的减小水锤压力，密封性能好，关闭无噪声。
Ge Yusheng, General Secretary with Chinese As sociation of Light Industry Machinery seriously mentioned that Baodao-B-3 low-noise, strong-suction V suction-ironing table is unique in its kind, which successfully overcame the ins ufficient suction of old ironing table with its suction wind strength up to 350 Pa, whose whole stroke of suction valve adopts stamping by machinery mould, leaving smooth suction door of good sealing and low-noise etc. My personal involvement in this quality inspection witnessed the proven quality of Baodao brand.
中国轻工机械协会秘书长，高级工程师葛余生认真地讲宝岛牌YTT-B-3型低噪音强吸风，V型吸风烫台与同行业生产的不一样，很具有特色，解决了过去老式烫台吸风不足的弊病，吸风压强最高达350Pa，吸风阀门全程采用机械模具冲制，使风门光洁畅顺及密封性好，噪音低等特点(我亲自参加了这次质量检测，宝岛品牌名副其实)，宝岛品质国内一流，与国际同步，替代进口，价格从优。
If a new plant expansion project selection Vinylon a DN200 sleeve valve, the above-mentioned three kinds of phenomena exist, DN300 beating along the pipeline, valve plug rotation, the noise more than 100 db, resonant 100X Diaphragm Control Ball valves opening 20~70%, given the resonance opening degree in favor of a two-seat valve, the resonance disappeared, put into operation to normal.
如某维尼纶厂新扩建工程选用一台DN200套筒阀，上述三种现象都存在，DN300的管道随之跳动，阀塞旋转，噪音100多分贝，共振开度20～70%，考虑共振开度大，改用一台双座阀后，共振消失，投运正常。
Simple structure, water Motorized Valve Actuators attack, the biggest back to 50%, the noise and the valve work frequently, short life.
结构简单、耐水击、最大背为50%，有噪音，阀片工作频繁，使用寿命短。
The cause of main steam valve noise is determined through analysis of noise creating mechanism.
通过对噪声产生机理的分析，确定了主蒸汽阀噪声的生成原因，介绍了几种降噪措施及其效果，对电厂管道设计和阀门选型具有借鉴意义。
Use earplugs to eliminate noise, an eyeshade to kill the light, and turn the air-conditioning valve on high.
用耳塞降低噪音，用眼罩来遮光，把空调风调大点。
The protection of the 200X Pressure Reducing valves environment pollution has become a public nuisance environmental pollution control valve control valve noise and the main control valve leakage.
6保护环境环境污染已经成为公害，控制阀对环境的污染主要有控制阀噪声和控制阀的泄漏。
Microphony is essentially something that happens in sensitive valve preamplifiers, If it happens in solid-state power amplifiers the level is so far below the noise it is effectively non-existent.
微音在敏感真空管前置放大器方面是必须的，如果它是在固态功放下发生，迄今为止低于噪音的电平实际上是不存在的。
Inflating the container by high precision pressure regulating valve in the second inflating phase to compensate the balance of the pressure in the detecting system, we can shorten the detecting time and impove the precision. Data of differential pressure which are acquired on line are handled with least square fit to erase noise as the criterion of the leakage level.
该测试系统对利用高精度的电气比例调压阀对测试系统的充气环节进行第二次充气，以补充第一次充气所造成的压力与温度不平衡，缩短总检测时间；通过最小二乘拟合算法，消除测试中采集数据的误差，实现对燃油系统的快速准确检测。
Beijing Machine by direct acting electro-hydraulic servo valve, Hangzhou Seiko's mechanical and electrical hydraulic proportional relief valve low-noise, Ningbo Huatong fluid's flow of electric-hydraulic proportional pressure valve, both electrical and mechanical integration of high-tech products, and have been put into mass production, and achieved better economic benefits.
北京机床所的直动式电液伺服阀、杭州精工液压机电公司的低噪声比例溢流阀、宁波华液公司的电液比例压力流量阀，均为机电一体化的高新技术产品，并已投入批量生产，取得了较好的经济效益。
In this case the valve outlet mach number is 0.4andthe valve noise level is approximately 85 dBA.
在这种情况下，阀门的出口马赫数为0.4，阀门的声压级约85分贝。