Measurement Signal Effects on the Normal-Incidence Absorption Coefficient

Volume 1 ◽  
2004 ◽  
Author(s):  
Kuang-Yih Tsuei ◽  
Wen-Wang Jiang ◽  
Shu-Fen Kuo
Keyword(s):  
Plane Wave ◽  
Absorption Coefficient ◽  
Coherence Function ◽  
Normal Incidence ◽  
Measurement Procedure ◽  
Test System ◽  
Test Method ◽  
Impedance Tube ◽  
Measurement Results ◽  
Measurement Signal

This paper will demonstrate the signal effects on the normal-incidence absorption coefficient. The test method covers two microphones located in impedance tube to measure this coefficient. It should analyze the measurement procedure and formulae theoretically, furthermore to propose the coherence function as the criteria for measurement results. Experimentally, different signals, generated by a sound source, input to the loudspeaker in impedance tube to produce the plane wave and two microphones can measure the sound pressures. Through different time weightings and average times on the two microphone signals, and after analyzing results of the frequency response, the coherence function and the normal-incidence absorption coefficient, the coherence function is a major factor to check the normal-incidence absorption coefficient reliable, even the test system stable or not.

Sound Absorption Characteristics of Porous Steel Manufactured by Lost Carbonate Sintering

2009 ◽  
Vol 1188 ◽  
Author(s):  
Miao Lu ◽  
Carl Hopkins ◽  
Yuyuan Zhao ◽  
Gary Seiffert
Keyword(s):  
Absorption Coefficient ◽  
Pore Size ◽  
Sound Absorption ◽  
Single Layer ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Impedance Tube ◽  
Absorption Characteristics

AbstractThis paper investigates the sound absorption characteristics of porous steel samples manufactured by Lost Carbonate Sintering. Measurements of the normal incidence sound absorption coefficient were made using an impedance tube for single-layer porous steel discs and assemblies comprising four layers of porous steel discs. The sound absorption coefficient was found not to vary significantly with pore size in the range of 250-1500 μm. In general, the absorption coefficient increases with increasing frequency and increasing thickness, and peaks at specific frequencies depending on the porosity. An increase in porosity tends to increase the frequency at which the sound absorption coefficient reaches this peak. An advantage was found in using an assembly of samples with gradient porosities of 75%-70%-65%-60% as it gave higher and more uniform sound absorption coefficients than an assembly with porosities of 75%.

TEST METHOD TO DETERMINE THE ACOUSTIC PROPERTIES OF BUILDING MATERIAL BY USING MICROPHONE IMPEDANCE TUBE

Akustika ◽  
2021 ◽  
pp. 36-42
Author(s):  
Sourabh Dogra ◽  
Arpan Gupta
Keyword(s):  
Reflection Coefficient ◽  
Absorption Coefficient ◽  
Virtual Instrument ◽  
Building Materials ◽  
Low Cost ◽  
Test Method ◽  
Wood Fibre ◽  
Acoustic Properties ◽  
Impedance Tube ◽  
Acoustical Properties

The paper discusses a simple and low-cost method to design four microphone impedance tube of measuring the acoustic properties of building materials. The acoustic properties of the material are defined by the reflection coefficient, absorption coefficient, and transmission coefficient. The experimental setup follows the ASTM-E2611 standard of four microphone impedance tube with two load boundary conditions to measure these coefficients. The setup consists of four microphones around a brass tube with the speaker at one end and termination at the other. Raw data from the four microphones is obtained through a Virtual Instrument (VI) program developed in LabView. The novelty in the design is the tapered connection between the two pipes connected via the sample holder. The mathematical equation involved in estimating acoustical properties is solved in MATLAB 2019a. The reflection and absorption coefficient data of ephony fibbrette of 15 mm thickness are compared with the data provided by an accredited laboratory. The experimental results of the in-house designed impedance tube are in good agreement with the lab results. This material is used in the auditorium, theatres for hearing comfort. Further, two new samples of ephony fibbrette along with wood fibre cement and damper has been analysed. It has been found that adding a layer of wood fibre results in an increase in the absorption coefficient whereas the addition of the damper results in an increase in the reflection coefficient.

scholarly journals Evaluation of a Preclinical Blood Test for Scrapie in Sheep Using Immunocapillary Electrophoresis

2006 ◽  
Vol 89 (3) ◽  
pp. 720-727 ◽  
Author(s):  
Roy Jackman ◽  
David J Everest ◽  
Mary Jo Schmerr ◽  
Mohammed Khawaja ◽  
Pat Keep ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Prion Protein ◽  
Clinical Signs ◽  
Test System ◽  
Buffy Coat ◽  
Infected Sheep ◽  
Test Method ◽  
Peptide Sequence ◽  
Transmissible Spongiform Encephalopathies ◽  
Blood Samples

Abstract An analytical method is described for detection of endogenous disease-associated prion protein in the buffy coat fraction from the blood of sheep infected with scrapie. The method has been improved and evaluated for its performance in the preclinical diagnosis of ovine transmissible spongiform encephalopathies. The test system uses a protocol for sample preparation that includes extraction and concentration and a test method that uses a liquid-phase competitive immunoassay for prion protein. Antibodies directed to a peptide sequence at the C-terminus of the prion protein (PrP) and a fluorescein-labeled peptide conjugate are used in the assay. Free zone capillary electrophoresis with laser-induced fluorescence for detection is used to separate the antibody-bound fluorescently labeled peptide and free labeled peptide. In this assay, the PrP competes with the fluorescently labeled peptide for limited antibody binding sites, which results in a reduction of the peak representing the immunocomplex of the antibody bound to the fluorescently labeled peptide. When blood samples from scrapie-infected sheep aged 712 months and of the scrapie-susceptible PrP genotypes VRQ/VRQ and VRQ/ARQ were analyzed, the abnormal PrP was found in blood samples. These results correlated with the post-mortem diagnosis of scrapie. The sheep were preclinical and appeared normal at the time of testing but later died with clinical disease approximately 12 months after testing. In older animals, and those with clinical signs, a smaller percentage of animals tested positive. This study has demonstrated that this technology can be used as a sensitive, rapid preclinical test to detect the disease-associated PrP in the blood of scrapie-infected sheep. Improvements in the extraction protocol and capillary electrophoresis conditions will enhance the robustness of this test.

The Research of IC Test Based on LTX-77 Test System

2014 ◽  
Vol 496-500 ◽  
pp. 1176-1179
Author(s):  
Li Tan ◽  
Yu Fang
Keyword(s):  
Test Object ◽  
Test System ◽  
Test Method ◽  
Test Results ◽  
Analog Ic ◽  
Test Platform ◽  
Logic Functions ◽  
Actual Test ◽  
Ic Test

LTX-77 test system is a large IC test system that is used for various kinds of analog IC, digital IC and analog digital mixed IC. It can be used to test DC parameters, AC parameters and logic functions. In the paper, the IC test platform is LTX-77 test system. IC ADC0804 was tested as the test object. The test method of IC is described in the view of actual test. The test results show that the test system is convenient and accurate, which has important practical value for IC manufacturers and users.

Design on Hierarchical Testing System for Unmanned Ground Vehicles

2011 ◽  
Vol 346 ◽  
pp. 817-822 ◽  
Author(s):  
Xin Li ◽  
Guang Ming Xiong ◽  
Yang Sun ◽  
Shao Bin Wu ◽  
Jian Wei Gong ◽  
...  
Keyword(s):  
Evaluation System ◽  
Test System ◽  
Unmanned Vehicles ◽  
Intelligent Vehicles ◽  
Test Method ◽  
Unmanned Ground Vehicles ◽  
Ground Vehicles ◽  
Test Environment ◽  
Test And Evaluation ◽  
Comprehensive Test

The test system for technical abilities of unmanned vehicles is gradually developed from the single test to comprehensive test. The pre-established test and evaluation system can promote the development of unmanned ground vehicles. The 2009 Future Challenge: Intelligent Vehicles and Beyond (FC’09) pushed China's unmanned vehicles out of laboratories. This paper proposed to design a more scientific and comprehensive test system for future competitions to better guide and regulate the development of China's unmanned vehicles. According to the design idea of stage by stage and level by level, the hierarchical test content from simple to advanced, from local to overall is designed. Then the hierarchic test environment is established according to the levels of test content. The test method based on multi-platform and multi-sensor is put forward to ensure the accuracy of test results. The testing criterion framework is set up to regulate future unmanned vehicle contests and to assess the unmanned vehicles scientifically and accurately.

scholarly journals Application of the plasticity characteristic determined by the indentation technique for evaluation of mechanical properties of coatings: I. specific features of the test method procedure

2004 ◽  
Vol 36 (1) ◽  
pp. 27-41 ◽  
Author(s):  
A.V. Byakova ◽  
Yu.V. Milman ◽  
A.A. Vlasov
Keyword(s):  
Mechanical Properties ◽  
Indentation Load ◽  
Test Method ◽  
Simplified Model ◽  
Micro Hardness ◽  
Properties Of Coatings ◽  
Modified Model ◽  
Plasticity Characteristic ◽  
Measurement Results ◽  
Hardness Values

Specific features of the test method procedure capable for determining the plasticity characteristic dH by indentation of inhomogeneous coatings affected by residual stress was clarified. When the value of the plasticity characteristic for coating was found to be as great as dH > 0.5 a simplified model was found to be reasonably adequate, while a modified model assumed compressibility of the deformation core beneath indentation. The advantage of the modified approach compared to the simplified one was grounded experimentally only if the elastic deformation for coating becomes greater than ?e ? 3.5%, resulting in the decrease of plasticity characteristic dH < 0.5. To overcome non accuracy caused by the effect of the scale factor on measurement results a comparison of different coatings was suggested using stabilized values of the plasticity characteristic dH determined under loads higher than critical, P ? Pc, ensuring week dependence of micro hardness values on the indentation load.

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