An effective experimental method for identifying radiated noise of different angular ranges for the rolling-piston compressor

2008 ◽  
Vol 222 (12) ◽  
pp. 2409-2417 ◽  
Author(s):  
Z Huang ◽  
W Jiang ◽  
H Zhang ◽  
C Liu ◽  
H Jin ◽  
...  
Keyword(s):  
Experimental Method ◽  
Noise Level ◽  
Angular Position ◽  
Piston Compressor ◽  
Low Noise ◽  
Discharge Process ◽  
Transform Method ◽  
Starting Position ◽  
Rolling Piston ◽  
Low Noise Design

In the traditional analysis method of noise signals, it is very difficult to relate the overall noise from compressors to the angular position. The experimental method of separating the overall noise of different angular ranges is carried out at the real conditions. The starting position of the rotary piston is labelled with vane displacement and the test signals are synchronously sampled. Experimental results are analysed through fast Fourier transform method based on different angular ranges, which displays the following useful conclusions. The experiment technology could effectively identify the angular ranges for the frequency bands with prominent noise level; for the experimental rolling-piston compressor, the vibration, and sound pressure level of the discharge process (210–360 angular degrees) are the largest above the frequency 500 Hz. The discharge process is divided into three parts, where the final part contributes a little to the overall noise level when compared with the other two stages. Pressure pulsation is an important source of vibration and noise and its suppression of peak frequencies is the key of low-noise design of the compressor.

LOW-NOISE SILICON-ON-INSULATOR HALL DEVICES

2004 ◽  
Vol 04 (02) ◽  
pp. L345-L354 ◽  
Author(s):  
Y. HADDAB ◽  
V. MOSSER ◽  
M. LYSOWEC ◽  
J. SUSKI ◽  
L. DEMEUS ◽  
...  
Keyword(s):  
Noise Level ◽  
Low Voltage ◽  
Silicon Layer ◽  
Electrical Current ◽  
Low Noise ◽  
Silicon On Insulator ◽  
Technological Parameters ◽  
Wide Range ◽  
Hall Sensors ◽  
Soi Technology

Hall sensors are used in a very wide range of applications. A very demanding one is electrical current measurement for metering purposes. In addition to high precision and stability, a sufficiently low noise level is required. Cost reduction through sensor integration with low-voltage/low-power electronics is also desirable. The purpose of this work is to investigate the possible use of SOI (Silicon On Insulator) technology for this integration. We have fabricated SOI Hall devices exploring the useful range of silicon layer thickness and doping level. We show that noise is influenced by the presence of LOCOS and p-n depletion zones near the edges of the active zones of the devices. A proper choice of SOI technological parameters and process flow leads to up to 18 dB reduction in Hall sensor noise level. This result can be extended to many categories of devices fabricated using SOI technology.

Comparison of Noise Reduction Performance Evaluation Methods for Low-Noise Pavement in Korea- Part

2021 ◽  
Vol 263 (4) ◽  
pp. 2930-2939
Author(s):  
Byungchae Kim ◽  
Hyunjin Kim ◽  
Wonuk Kang
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
Measurement Method ◽  
Road Traffic ◽  
Low Noise ◽  
Management Standards ◽  
Close Proximity ◽  
Porous Pavement ◽  
Reduction Effect ◽  
Measurement Location

In Korea, road noise is assessed as a measurement method of exterior noise emitted by road vehicle for management standards by the National Institute of Environmental Sciences. In this method, the noise felt at the actual pickup point is measured as LAeq (the roadside equivalent noise level). Recently, to clarify the standard for measuring noise on low-noise pavements, the CPX (ISO11819-2; Close-proximity method) was first introduced in the Porous Pavement Guidelines of the Ministry of Land, Infrastructure and Transport. According to ISO, the CPX adopts the side microphone as a mandatory measurement location, and the rear optional. The side location has been a mandatory due to its high correlation with SPB (ISO 11819-1, Statistical Pass-by method). However, according to our previous study on the correlation evaluation between L and CPX rear microphone noise level, both noise reduction effect was about 9-12 dB(A) showed a high correlation in Korea where heavy road traffic is common. The following study aims to show the consistent correlation between the L and CPX rear noise level. Furthermore, it is intended to be helpful in selecting the location of the CPX microphone that can most effectively represent the actual noise on the low-noise pavement in Korea.

Experimental Measurement of Oil Droplets Size and Velocity Above the Rotor/Stator in a Rotary Compressor

2021 ◽  
Author(s):  
Puyuan Wu ◽  
Jun Chen ◽  
Paul E. Sojka ◽  
Yang Li ◽  
Hongjun Cao
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Outer Region ◽  
Droplet Size Distribution ◽  
Rotary Compressor ◽  
Discharge Process ◽  
Oil Droplets ◽  
Lower Cavity ◽  
Lubricant Oil ◽  
Rolling Piston

Abstract Hundreds of millions of Air conditioning (AC) systems are produced each year. Many of them, especially small AC appliances, use rotary compressors as the system’s heat pump due to their simple structure and high efficiency in a small system. Lubricant oil is used in the rotary compressor to lubricate the moving parts, such as the crankshaft and the rolling piston, and to seal the clearance between the sliding parts, e.g., the clearance between the rolling piston and the cylinder, and the vane and the cylinder. As the compressed refrigerant vapor is discharged from the cylinder through the discharge port, part of lubricant oil in the cylinder would be carried by the vapor and atomize into small droplets in the lower cavity during the discharge process, which is complicated and highly-coupled. Some of these oil droplets would ultimately be exhausted from the compressor and enter other parts in the system, reducing the compressor reliability and deteriorating the heat transfer of the condenser and the evaporator in the system. Our previous research studied the atomization of the lubricant oil during the discharge process in the compressor’s lower cavity. However, the oil droplets’ behavior downstream of the lower cavity is unknown. Thus, studying the oil droplets’ behavior after passing through the rotor/stator can help understand how the rotor/stator would affect the droplet size distribution and movement, thus controlling the flow rate of escaped oil droplets. In this study, a hot gas bypass test rig is built to run a modified rotary compressor with sapphire windows right above the rotor/stator. The oil droplets’ size distribution and movement along the radial direction are obtained at the shaft’s rotating frequency of 30 and 60 Hz by shadowgraph. It is found that droplet size at 30 and 60 Hz varies little in the inner region of the rotor/stator clearance and would increase sharply above the clearance and keep increasing in the outer region of the clearance. More importantly, droplet velocity has a downward velocity component at the inner region and an upward velocity component at the outer region of the rotor/stator clearance. With the result of droplet size distribution and droplet velocity above the rotor/stator, we propose the model of the oil droplet’s path above the rotor/stator, which can be understood as the coupling of a swirling jet and a rotating disk.

Carbon-doped single-crystalline SiGe/Si thermistor with high temperature coefficient of resistance and low noise level

2010 ◽  
Vol 97 (22) ◽  
pp. 223507 ◽  
Author(s):  
H. H. Radamson ◽  
M. Kolahdouz ◽  
S. Shayestehaminzadeh ◽  
A. Afshar Farniya ◽  
S. Wissmar
Keyword(s):  
High Temperature ◽  
Temperature Coefficient ◽  
Noise Level ◽  
Low Noise ◽  
Temperature Coefficient Of Resistance ◽  
Single Crystalline ◽  
Carbon Doped

A Low-Noise Design Technique for High-Speed CMOS Optical Receivers

2014 ◽  
Vol 49 (6) ◽  
pp. 1437-1447 ◽  
Author(s):  
Dan Li ◽  
Gabriele Minoia ◽  
Matteo Repossi ◽  
Daniele Baldi ◽  
Enrico Temporiti ◽  
...  
Keyword(s):  
High Speed ◽  
Low Noise ◽  
Optical Receivers ◽  
Design Technique ◽  
Low Noise Design

A Comparison of Beat Frequency Estimation Methods for Large Ring Laser

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Jailos Mrisho Nzumile ◽  
Keyword(s):  
Real Time ◽  
Noise Level ◽  
Ring Laser ◽  
Frequency Estimation ◽  
Low Noise ◽  
Estimation Methods ◽  
Acquisition Rate ◽  
Large Ring ◽  
True Value ◽  
Output Characteristics

Autoregressive (AR2) technique has always been used to estimate frequency of the output signal from Large ring laser. However, the acquisition rate is not at near real time which is the requirement and noise level still challenge the process resulting to errors in the final estimation. A research was done to compare the Autoregressive (AR2) with the counterparts such as Pisarenko, Quinn, Hilbert and Phase looking for a better technique that will estimate the frequency at near real time to minimize errors. Secondary data from G and C – II ring laser were used during the comparison between the techniques and Autoregressive (AR2). Results shows that, the output characteristics from the counterpart does not depict the oscillations of the Earth rotation as expected contrast to that of Autoregressive (AR2) which does. Moreover, there were much deviation from the expected true value for the techniques contrast to that of AR2 which is very minimum. On the other hand, when the C – II data were used, it was observed that both techniques resemble on their output characteristics though AR2 was still better in the acquisition rate expect for Hilbert transform which does not resemble with others. Following the scope of this paper, Autoregressive (AR2) technique still emerge as a favorite frequency estimation technique contrast to the four counterparts due to its robustness, high acquisition rate as well as low noise level.

A filter with a guaranteed asymptotic performance

1993 ◽  
Vol 441 (1911) ◽  
pp. 33-57
Keyword(s):  
Kalman Filter ◽  
Probability Density Function ◽  
Probability Density ◽  
Density Function ◽  
Extended Kalman Filter ◽  
Noise Level ◽  
Low Noise ◽  
The State ◽  
Optimal Probability ◽  
Expected Values

In the case of low noise levels the optimal probability density function summarizing the available information about the state of a system can be accurately approximated by the product of a gaussian function and a linear function. The approximation preserves the ability to estimate to an accuracy of O ( λ -2 ) the expected value of any twice continuously differentiable function defined on the state space. The parameter λ depends on the noise level. If the noise level in the system is low then λ is large. A new filtering method based on this approximation is described. The approximating function is updated recursively as the system evolves with time, and as new measurements of the system state are obtained. The updates preserve the ability to estimate the expected values of functions to an accuracy of O ( λ -2 ). The new filter does not store previous measurements or previous approximations to the optimal probability density function. The new filter is called the asymptotic filter, because the definition of the filter and the analysis of its properties are based on the theory of asymptotic expansion of integrals of Laplace type. An analysis of the state propagation equations shows that the asymptotic filter performs better than a particular widely used suboptimal approximation to the optimal filter, the extended Kalman filter. The extended Kalman filter does not, in general, preserve the ability to estimate expected values to an accuracy of O ( λ -2 ). The computational cost of the asymptotic filter is comparable to that of the iterated extended Kalman filter.

A Simulation Study on Translational Piston Air Compressor

2011 ◽  
Vol 328-330 ◽  
pp. 628-632
Author(s):  
Kui Hua Geng ◽  
Meng Tang ◽  
Hong Dong Yu ◽  
Ai Nong Geng ◽  
Shi Guang Du
Keyword(s):  
Simulation Study ◽  
Relative Velocity ◽  
Friction And Wear ◽  
Kinetic Characteristic ◽  
Translational Motion ◽  
Piston Compressor ◽  
Working Principle ◽  
Rolling Piston ◽  
Rotary Speed ◽  
Conventional Rolling

The structure and working principle of a new translational piston compressor was introduced in this paper. Its piston works in a way of translational motion, hence reduces the piston’s relative velocity to cylinder and cap, as well as friction and wear. In order to avoid vane detaching from piston, simulations were carried out regarding the pre-tightening spring and an optimal preload of the spring was obtained. By analyzed and compared to conventional rolling piston compressor in term of contact force between vane and piston, it was pointed out that the new compressor possessed advantage of kinetic characteristic and is more suitable for the situation of high rotary speed.

Evaluation of Noise Characteristics of Drainage and Water Supply Systems in Apartment Bathrooms

2014 ◽  
Vol 1025-1026 ◽  
pp. 987-990
Author(s):  
Jun Oh Yeon ◽  
Kyoung Woo Kim ◽  
Kwan Seop Yang ◽  
Byung Kwon Lee
Keyword(s):  
Water Supply ◽  
Noise Level ◽  
Drainage System ◽  
Low Noise ◽  
Sound Level ◽  
Water Supply Systems ◽  
Apartment Building ◽  
Noise Characteristics ◽  
Measurement Results ◽  
Supply Systems

We have developed a low-noise drainage system, which was installed in bathrooms of apartment building units as well as in a mock-up test building, to evaluate the noise level in order to reduce the noise produced in the bathrooms of multiunit dwellings. The drainage system installed in the mock-up building consists of six types of detachable drains, and the level of noise produced during toilet use in the upper unit was measured in the lower unit. The measurement results showed that low-noise drainage 4 exhibited the Leq(equivalent continuous sound level) at 34.7 dB(A). The noise measurement results of various types of low-noise drains installed in an apartment building showed that the Leqduring toilet use was 46.7 dB(A) on average, and the Leqduring sink use was 40.5 dB(A) on average.

Measurement and Analysis of Noise Characteristics for Diesel Engine

2005 ◽  
Author(s):  
Guangpu Liu ◽  
Hongxia Pan ◽  
Jinying Huang
Keyword(s):  
Spectral Analysis ◽  
Diesel Engine ◽  
Noise Source ◽  
Low Noise ◽  
Coherence Analysis ◽  
Vehicle Interior ◽  
Noise Characteristics ◽  
Measurement And Analysis ◽  
Analysis System ◽  
Low Noise Design

The vehicle interior noise is mainly caused by irregularity of road, engine and transmission. So it is important to study on the noise characteristics for diesel engine and identify the main noise source and investigate the effective methods to control noise. In this paper, by using the measurement and analysis system, we measured the sound pressures levels and their curves the noise of a military diesel engine, then made spectral analysis and coherence analysis. The results provide bases for low noise design of this diesel engine.

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