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Important factors to consider when comparing acoustical data
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Important factors to consider when comparing acoustical data

刘涛 2015-06-16 13:42:02 0浏览

IntroductionWhen forced convection cooling is required, acoustical noise can often be a determining factor on which product or supplier is chosen. It is because of this that it is important to know that the acoustic data being compared was obtained using

Cooling Fan Noise - Sleeve Bearing vs Ball Bearing
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Cooling Fan Noise - Sleeve Bearing vs Ball Bearing

刘涛 2015-06-16 12:23:05 0浏览

IntroductionQuite often in low-flow electronic cooling fans for computers, where the aerodynamic noise is low, the predominant noise emitted by the fan is generated in the bearing system. This type of fan usually has either an oil-impregnated sleeve beari

Stall of Axial Flow Fans
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Stall of Axial Flow Fans

刘涛 2015-06-16 12:22:23 0浏览

IntroductionThe following paper describes the stall phenomena that occurs to the blades of a fan's propeller and explains its cause. To simplify the analysis, we are going to adopt certain assumptions that are described below:We assume incoming air to

Acoustic noise: causes, rating systems, and design guidelines
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Acoustic noise: causes, rating systems, and design guidelines

刘涛 2015-06-16 12:21:12 0浏览

Acoustic NoiseNoise is, to a great extent, a purely subjective personal phenomena. Perhaps the best definition of it is as an unwanted sound. Noise does, however, have two basic characteristics. The first is the physical phenomenon which can be measured a

Cooling System Design Tips
Design

Cooling System Design Tips

刘涛 2015-06-16 12:15:34 0浏览

Main ConsiderationsAir Flow, Distribution and System PressureThe greater the airflow and pressure of a given system, the greater the noise. Total airflow can often be minimized by carefully distributing flow. This is done by placing heat sources with high

Adaptive Cooling using Fan Speed Control
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Adaptive Cooling using Fan Speed Control

刘涛 2015-06-16 12:13:40 0浏览

Operating a fan or blower at full speed continuously, or cycling it on and off, is a sub optimal solution in most cooling and ventilating applications. Ideally, variable fan speed control should be used to maintain whatever speed is necessary to satisfy t

Ensuring the thermal integrity of your IC package/PC board design
Design

Ensuring the thermal integrity of your IC package/PC board design

刘涛 2015-06-09 10:26:05 4浏览

You just built a breadboard of your expert design. You did all the simulations needed before going to layout, and reviewed the manufacturer's suggested techniques for a good thermal design for the particular package chosen. You even did your due dilig

关于噪音
Design

关于噪音

刘涛 2015-06-03 10:11:07 5浏览

一、声音的产生 人耳听觉系统所能感受到的信号称为声音。从物理学观点来看,声音是一种机械波,是机械振动在弹性介质中的传播。 声波的产生可由图 7-1 来说明。图中 7-1 ( a )中 A 、 B 、 C 、 D ……表示连续弹性介质被分成单个小体积元,每个体积元含大量具有质量的介质分子,体积元之间存在着弹性作用。在宏观上,体积元可视为质点。 设想由于某一声源的振动在弹性介质某一局部区域激起一种扰动,使得该区域的介质质点...

恒温加热用PTC热敏电阻器
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恒温加热用PTC热敏电阻器

刘涛 2015-04-16 14:18:10 3浏览

产品概述恒温加热用PTC热敏电阻的恒温发热特性, 是由材料特性决定的。其原理是当PTC热敏电阻通上电后,因为自热,导致元件本体温度上升,电阻值进入跃变区,电流迅速下降,于是恒温加热PTC热敏电阻表面温度持续保持恒定值。该温度只与PTC热敏电阻的居里温度和外加电压有关,而与环境温度基本无关。PTC恒温加热器就是利用恒温加热PTC热敏电阻恒温发热特性设计的加热器件。在中小功率加热场合,PTC加热器具有恒...

Minimizing acoustical noise in electronic systems
Design

Minimizing acoustical noise in electronic systems

刘涛 2015-03-26 22:19:11 9浏览

IntroductionAir-moving devices (AMDs), such as fans and blowers used for cooling in electronic systems invariably generate acoustical noise which must be considered if people are exposed to the emitted noise. In this article, we discuss quantitative measu