Noise Spectrum Measurements from 10 Hz to 1 MHz using a Tunable Switching Radiometer. I. Instrumentation

1971 ◽  
Vol 49 (7) ◽  
pp. 849-852 ◽  
Author(s):  
H. A. Buckmaster ◽  
R. S. Rathie
Keyword(s):  
High Precision ◽  
Noise Source ◽  
Noise Spectrum ◽  
Measurement Precision ◽  
Frequency Range ◽  
Direct Reading ◽  
Spectrum Measurements ◽  
Averaging Time

The first application of a switching (Dicke) radiometer to high-precision, noise spectrum measurements from 10 Hz to 1 MHz is described. The solution of the instrumentation problems unique to this frequency range are discussed in detail. The advantage of this radiometer is that it can be employed in a null mode so that it is direct reading and the measurement precision at all frequencies is limited fundamentally by the bandwidth and averaging time or by the calibration of the reference noise source and its attenuator.

Adiabatische Korrektur der Born-Oppenheimer-Näherung beim GeS und GeSe / Adiabatic Correction of the Born-Oppenheimer Approximation for GeS and GeSe

1976 ◽  
Vol 31 (3-4) ◽  
pp. 374-380 ◽  
Author(s):  
W. U. Stieda ◽  
E. Tiemann ◽  
T. Törring ◽  
J. Hoeft
Keyword(s):  
Dipole Moment ◽  
High Precision ◽  
Electric Dipole Moment ◽  
Electric Dipole ◽  
Rotational Constant ◽  
Frequency Range ◽  
Rotational Spectra ◽  
Oppenheimer Approximation

Abstract The rotational spectra of GeS and GeSe were measured in the frequency range of 66 GHz to 110 GHz with high precision. The breakdown of the Born-Oppenheimer approximation was observed for the rotational constant yol. With the known molecular 37-factor and the electric dipole moment the adiabatic part of the Born-Oppenheimer correction can be extracted from the primary observa-tion on y01. The adiabatic correction is very similar in both molecules but differs from the results in the earlier measurements on PbS.

Noise Evaluation of Concrete Pavement

2013 ◽  
Vol 368-370 ◽  
pp. 1985-1989
Author(s):  
Ya Min Liu ◽  
Rao Rao Han ◽  
Zhi Jin Tao ◽  
Jie Chen
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
Noise Spectrum ◽  
Concrete Pavement ◽  
Noise Characteristic ◽  
Groove Width ◽  
Concrete Pavements ◽  
Frequency Range ◽  
Porous Concrete ◽  
Noise Evaluation

In order to evaluate noise characteristic of concrete pavements with different texture, specimens were prepared carefully by varying groove parameters, such as groove width and space between grooves. Employing tire impact method, the noise level and noise spectrum of different pavements were analyzed. The results indicate that the noise level of transverse grooved concrete pavement is the greatest, and the followings are glossy concrete pavement and longitudinal grooved concrete pavement, porous concrete pavement has the lowest noise level. For grooved pavement, the noise level is promoted with increasing the space between grooves. Besides that, the noise level of transverse grooved concrete pavement becomes greater as the groove width increases. For longitudinal grooved pavement, there is a contrary tendency. It is porous concrete pavement for a frequency larger than 1600HZ. In the whole frequency range, the noise-reduction ability of transverse grooved concrete pavement is the worst.

Analysis on Mechanical Properties of Instrumented Indentation Tester Frame

2012 ◽  
Vol 215-216 ◽  
pp. 895-898
Author(s):  
Jun Hong Guo ◽  
De Jun Ma ◽  
Wei Chen ◽  
Zhong Kang Song
Keyword(s):  
High Precision ◽  
Inclination Angle ◽  
Indentation Load ◽  
Measurement Precision ◽  
Instrumented Indentation ◽  
Element Analysis ◽  
Maximum Value ◽  
Load Analysis ◽  
The Relationship ◽  
Maximum Inclination

Finite element analysis is undertaken to identify the extent of loading deformation of instrumented indentation equipment frame which is a main part in High-precision instrumented indentation tester developed and realized by our group. The working load enacted in the model is varied from 10N to 100N, and the increment load is 10N. By plotting and fitting data of inclination angle and working load, the relationship between frame inclination angle and working load is established. The function of this relationship is θ=0.000024*F. When the working load is up to the upper bound 100N, the inclination angle of frame reaches the maximum value 0.00241°.Load analysis of push rod shows that the percent error between measured load values and real indentation load values caused by maximum inclination angle is in 10-8order. The conclusion is thus derived that frame inclination has nearly no effects on load measurement precision. The research in this paper confirms that the design of frame belonging to High-precision instrumented indentation tester is appropriate.

Noise Source Identification of the Grain Combining Harvester Based on Acoustic Array Test

2020 ◽  
Vol 36 (6) ◽  
pp. 879-890
Author(s):  
Yujun Shang ◽  
Chenglong Wang ◽  
Hongmei Xu ◽  
Shuang Liu ◽  
Wei Jiang ◽  
...  
Keyword(s):  
Source Identification ◽  
Noise Level ◽  
Noise Source ◽  
Noise Pollution ◽  
Rear Side ◽  
List Type ◽  
Frequency Range ◽  
Noise Source Identification ◽  
Combine Harvester ◽  
Acoustic Array

HIGHLIGHTSWe tested the noise of a grain combining harvester using a spiral acoustic array, aiming to identify its main sources and reduce its noise level.The noise of the harvester is mainly concentrated in the frequency range of 1 to 4 kHz.When the power of other devices is cut off, engine is the main noise source. While all devices are in normal working condition, the main source of noise is the header device and the intermediate conveying device.Abstract. The grain combine harvester is an important agricultural equipment with multiple functions of harvesting, threshing, separating, cleaning and grain gathering. As an instantaneous physical pollution, noise has become one of the main causes of modern civilization diseases. The noise generated by the operation of harvesters not only causes harm to the workers, but also leads to environmental noise pollution. Here, we tested the noise of a grain combine harvester using a spiral acoustic array, aiming to identify its main source by noise source identification technology based on the sound pressure distribution and reduce its noise level. The test results show that the noise of the harvester is mainly concentrated in the frequency range of 1 to 4 kHz. When the power of other devices is cut off, the engine is the main noise source, while under normal working conditions of all devices, the main source of noise is the header device and the intermediate conveying device on the front side of the harvester, the threshing device on the rear side, the engine and the threshing device on the left side, and the engine and the header device on the right side. Keywords: Acoustic array technology, Grain combining harvester, Noise source identification, Vibration and noise reduction.

Site evaluation and RFI spectrum measurements in Portugal at the frequency range 0.408–10GHz for a GEM polarized galactic radio emission experiment

New Astronomy ◽  
2006 ◽  
Vol 11 (8) ◽  
pp. 551-556 ◽  
Author(s):  
Rui Fonseca ◽  
Domingos Barbosa ◽  
Luis Cupido ◽  
Ana Mourão ◽  
Dinis M. dos Santos ◽  
...  
Keyword(s):  
Radio Emission ◽  
Frequency Range ◽  
Spectrum Measurements ◽  
Site Evaluation ◽  
Galactic Radio Emission ◽  
Galactic Radio

Noise spectrum measurements of a midwave, interband cascade infrared photodetector with 33 nm wide electron barrier

2013 ◽  
Author(s):  
Laura A. Treider ◽  
Vincent M. Cowan ◽  
Christian P. Morath ◽  
Zhaobing Tian ◽  
Sanjay Krishna
Keyword(s):  
Noise Spectrum ◽  
Infrared Photodetector ◽  
Spectrum Measurements

The Noise Characteristics Research in Subway Cars

2014 ◽  
Vol 1051 ◽  
pp. 431-434
Author(s):  
Jian Hui Tian ◽  
Lian Jian ◽  
Bing Li
Keyword(s):  
Real Time ◽  
High Frequency ◽  
Noise Spectrum ◽  
Frequency Range ◽  
Noise Characteristics ◽  
Spectrum Distribution ◽  
Spectrum Characteristics ◽  
Relationship Of ◽  
The Relationship

The noise of different points in four sections of Shenzhen subway was tested by this paper. Real-time SPL and noise spectrum distribution curves at bogie were given, while the equivalent SPL curve was also shown. The relationship of subway speed and noise SPL was investigated. The regular of noise spectrum characteristics and SPL was obtained. The results show that the noise SPL increases with the increase of the speed. Looking from the frequency range, the frequency corresponding to larger noise SPL amplitude mainly concentrates in the lower frequency while the subway stopping, the frequency corresponding to larger noise SPL amplitude mainly concentrates in high frequency while the subway running.

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