A Simple Approach to Characterize Finite Compressibility of Elastomers

2003 ◽  
Vol 76 (4) ◽  
pp. 912-922 ◽  
Author(s):  
Mark R. Gurvich ◽  
Thomas S. Fleischman
Keyword(s):  
Carbon Black ◽  
Bulk Modulus ◽  
Experimental Verification ◽  
Material Properties ◽  
Numerical Approach ◽  
Simple Approach ◽  
Experimental Measurements ◽  
Axially Loaded ◽  
Different Levels

Abstract A hybrid experimental-numerical approach is proposed for accurate dimensionless characterization of rubber finite compressibility. Rubber specimens in the form of bonded rubber disks are considered as elastomeric structures with unknown material properties. These properties are calculated by matching results of FEA with experimental measurements of radial deformations of the axially-loaded disks. The approach may be used for reliable characterization of Poisson's ratio, bulk modulus, or other characteristics of interest. Implementation of the approach is considered for two representative elastomeric compounds with different levels of carbon black. Good experimental verification of the approach is shown at different levels of loading. Moreover, the same parameters of finite compressibility are independently obtained using both compressive and tensile loads. Higher compressibility is observed for a compound with larger content of carbon black as expected.

Characterization of a Server Thermal Mass Using Experimental Measurements

2011 ◽  
Author(s):  
Mahmoud Ibrahim ◽  
Furat Afram ◽  
Bahgat Sammakia ◽  
Kanad Ghose ◽  
Bruce Murray ◽  
...  
Keyword(s):  
Material Properties ◽  
Data Center ◽  
Open Space ◽  
Heat Dissipation ◽  
Thermal Mass ◽  
Experimental Measurements ◽  
Close Monitoring ◽  
Safe Operation ◽  
Dynamic Cooling

The inevitable increase in the heat dissipation of data center facilities is requiring more efficient approaches in the operation of a data center. Dynamic cooling has been proposed as the approach for enhancing the energy efficiency. Dynamic cooling involves close monitoring of the data center environment with time, using sensors, and taking real time decisions on allocating the cooling resources based on the location of hotspots and concentration of workloads. In order to address this approach, knowing the time it takes for a facility to reach steady state after any variation is crucial for ensuring safe operation of the electronic equipment at all times, and it is a function of thermal mass. The thermal mass of an object is the amount of mass capable of withholding heat, and the time it takes to dissipate that heat into the environment is a function of the material properties. In this study, we use a typical 2U server and explain a procedure in obtaining its thermal mass. The server is operated at different controlled power levels while measurements of fans speed, component temperatures, and inlet and outlet temperatures are taken with time. For the first set of experiments, the server is kept inside a chamber and for the second set it is kept in open space. Ultimately the experimental measurements obtained will be used to obtain a compact model to approximate thermal mass of different servers.

scholarly journals Longitudinal Monostatic Acoustic Effective Bulk Modulus and Effective Density Evaluation of Underground Soil Quality: A Numerical Approach

2020 ◽  
Vol 11 (1) ◽  
pp. 146
Author(s):  
Yuqi Jin ◽  
Tae-Youl Choi ◽  
Arup Neogi
Keyword(s):  
Bulk Modulus ◽  
Material Properties ◽  
Numerical Approach ◽  
Layered Material ◽  
Effective Density ◽  
Effective Bulk Modulus ◽  
Fluid Environment ◽  
Density Evaluation ◽  
Novel Method ◽  
Air Void

In this study, we introduce a novel method using longitudinal sound to detect underground soil voids to inspect underwater bed property in terms of effective bulk modulus and effective density of the material properties. The model was simulated in terms of layered material within a monostatic detection configuration. The numerical model demonstrates the feasibility of detecting an underground air void with a spatial resolution of about 0.5 λ and can differentiate a soil firmness of about 5%. The proposed technique can overcome limitations imposed by conventional techniques that use spacing-consuming sonar devices and suffer from low penetration depth and leakage of the transverse sound wave propagating in an underground fluid environment.

scholarly journals Simultaneous determination of various platycosides in Four Platycodon grandiflorum cultivars by UPLC-QTOF/MS

2019 ◽  
Vol 62 (1) ◽  
Author(s):  
Dae Young Lee ◽  
Bo-Ram Choi ◽  
Jae Won Lee ◽  
Yurry Um ◽  
Dahye Yoon ◽  
...  
Keyword(s):  
Principal Component ◽  
Ultra Performance Liquid Chromatography ◽  
Platycodon Grandiflorum ◽  
Pentacyclic Triterpenoid ◽  
Flight Mass Spectrometry ◽  
Platycodi Radix ◽  
Isomeric Pairs ◽  
Different Levels

Abstract In Platycodi Radix (root of Platycodon grandiflorum), there are a number of platycosides that consist of a pentacyclic triterpenoid aglycone and two sugar moieties. Due to the pharmacological activities of platycosides, it is critical to assess their contents in PR, and develop an effective method to profile various platycosides is required. In this study, an analytical method based on ultra performance liquid chromatography coupled with quadrupole time-of-flight/mass spectrometry (UPLC-QTOF/MS) with an in-house library was developed and applied to profile various platycosides from four different Platycodi Radix cultivars. As a result, platycosides, including six isomeric pairs, were successfully analyzed in the PRs. In the principal component analysis, several platycosides were represented as main variables to differentiate the four Platycodi Radix cultivars. Their different levels of platycosides were also represented by relative quantification. Finally, this study indicated the proposed method based on the UPLC-QTOF/MS can be an effective tool for identifying the detail characterization of various platycosides in the Platycodi Radix.

scholarly journals Spectral Decomposition of the Flow and Characterization of the Sound Signals through Stenoses with Different Levels of Severity

2021 ◽  
Vol 8 (3) ◽  
pp. 41
Author(s):  
Fardin Khalili ◽  
Peshala T. Gamage ◽  
Amirtahà Taebi ◽  
Mark E. Johnson ◽  
Randal B. Roberts ◽  
...  
Keyword(s):  
Pressure Fluctuations ◽  
High Energy ◽  
Sound Sources ◽  
Severity Level ◽  
Non Invasive ◽  
Flow Through ◽  
Severity Of The Disease ◽  
Proper Orthogonal ◽  
Different Levels

Treatments of atherosclerosis depend on the severity of the disease at the diagnosis time. Non-invasive diagnosis techniques, capable of detecting stenosis at early stages, are essential to reduce associated costs and mortality rates. We used computational fluid dynamics and acoustics analysis to extensively investigate the sound sources arising from high-turbulent fluctuating flow through stenosis. The frequency spectral analysis and proper orthogonal decomposition unveiled the frequency contents of the fluctuations for different severities and decomposed the flow into several frequency bandwidths. Results showed that high-intensity turbulent pressure fluctuations appeared inside the stenosis for severities above 70%, concentrated at plaque surface, and immediately in the post-stenotic region. Analysis of these fluctuations with the progression of the stenosis indicated that (a) there was a distinct break frequency for each severity level, ranging from 40 to 230 Hz, (b) acoustic spatial-frequency maps demonstrated the variation of the frequency content with respect to the distance from the stenosis, and (c) high-energy, high-frequency fluctuations existed inside the stenosis only for severe cases. This information can be essential for predicting the severity level of progressive stenosis, comprehending the nature of the sound sources, and determining the location of the stenosis with respect to the point of measurements.

Preparation and characterization of carbon black diamond composite electrodes for anodic degradation of phenol

2015 ◽  
Vol 153 ◽  
pp. 379-384 ◽  
Author(s):  
Mohammed A. Ajeel ◽  
Mohamed Kheireddine Aroua ◽  
Wan Mohd Ashri Wan Daud
Keyword(s):  
Carbon Black ◽  
Composite Electrodes ◽  
Diamond Composite
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