scholarly journals Impact of spineless cactus cultivation (O. Ficus-indica) on the thermal characteristics of soil

2018 ◽  
Vol 13 (1) ◽  
pp. 1
Author(s):  
Willames De Albuquerque Soares
Keyword(s):  
Heat Capacity ◽  
Thermal Characteristics ◽  
Thermal Characterization ◽  
Biological Processes ◽  
Volumetric Heat Capacity ◽  
Average Value ◽  
Brazilian Semiarid ◽  
Cultivation Techniques ◽  
Soil Changes

Temperature is a fundamentally important factor for understanding the physical, chemical, and biological processes that occur in soil. However, there are few studies in the Brazilian semiarid zone that seek to understand how soil degradation affects its thermal characteristics. The objective of this study was to evaluate the influence of cultivation techniques on the thermal characterization of soil, using the model proposed by Johansen. The study was conducted in the Agreste region of the state of Pernambuco, Brazil on two plots of land, one with native vegetation (Caatinga) and the other with spineless cactus (O. ficus - indica). It was observed that the procedures used to prepare the soil for cultivation of spineless cactus caused a reduction in the capacity to transmit the surface temperature to the interior of the soil. Changes in the physical properties of the soil required for cultivation resulted in a reduction in the average value of the volumetric heat capacity of about 22%; an increase of approximately 5% in the average volumetric heat capacity and a 26% increase in the thermal diffusivity of the soil, as well as a reduction of approximately 50% in the heat flux from the surface of the soil.

Thermal Characterization of Non-Isolated DC to DC Convertor

2011 ◽  
Author(s):  
Shiladitya Chakravorty ◽  
Bahgat Sammakia ◽  
Varaprasad Calmidi
Keyword(s):  
Power Dissipation ◽  
High Performance ◽  
Field Effect Transistors ◽  
Thermal Characteristics ◽  
Thermal Characterization ◽  
Input Voltage ◽  
Thermal Design ◽  
Power Module ◽  
Improved Performance

Improved performance of semiconductor devices in recent years has resulted in consequent increase in power dissipation. Hence thermal characterization of components becomes important from an overall thermal design perspective of the system. This study looks at a high performance non-isolated point of load power module (a DC to DC converter) meant for advanced computing and server applications. Thermal characteristics of the module were experimentally analyzed by placing the power module on a bare test board (with no insulation) inside a wind tunnel with thermocouples attached to it. There were three devices on this module that dissipate power. There were two FETs (Field Effect Transistors) and an inductor which can be considered as sources. The consolidated power dissipation from the module was calculated by measuring the input voltage and input current while keeping the output voltage and current constant. Temperatures at various points on the module and the test card were recorded for different air flow velocities and overall power dissipation. Subsequently this set up was numerically analyzed using a commercially available computational fluid dynamics (CFD) code with the objective of comparing the results with experimental data previously obtained.

Thermal Characterization of Bacterial Cellulose/Polyvinyl Alcohol Nanocomposite

2015 ◽  
Vol 1123 ◽  
pp. 303-307 ◽  
Author(s):  
Akhmad Zainal Abidin ◽  
Hafis Pratama Rendra Graha
Keyword(s):  
Bacterial Cellulose ◽  
Melting Temperature ◽  
Healing Process ◽  
Thermal Characteristics ◽  
Cost Effective ◽  
Thermal Characterization ◽  
Fermentation Medium ◽  
Scanning Calorimetry ◽  
Regeneration Rate

Bacterial cellulose (BC) is a natural polymer which can be produced from various substrates easily found in Indonesia. Bacterial cellulose is believed to be a promising and cost effective bone scaffold in which a bone regeneration rate enhanced so the healing process is faster. In this experiment, Bacterial Cellulose (BC)/ Polyvin y l Alcohol (PVA) nanocomposite was made to give a further improvement in the properties. This nanocomposite was made thorough BC biosynthesis in Gluconacetobacter xylinus fermentation medium that was modified by addition of PVA. The PVA concentrations were varied as 0, 3, 6, 9, and 12 % w of fermentation medium. The culture had been agitated by magnetic stirrer for 28 days before freeze drying method was conducted to obtain dry BC/PVA nanocomposite. The product of BC/PVA nanocomposite was then studied for thermal characteristics using Differential Scanning Calorimetry (DSC) and Thermogravimetry Analysis (TGA). Pure BC has melting temperature (Tm) at 350 . 3oC and pure PVA at 181 . 3oC. Experimental results showed that the higher PVA content in fermentation medium decreased the melting temperature of BC/PVA nanocomposite produced.

scholarly journals Thermophysical Characterization of Granite, Basalt and Marble Ornamental Stones in Benin

2019 ◽  
pp. 1-6
Author(s):  
Bachir Kolade Adedokun Ambelohoun ◽  
Chakirou Akanho Toukourou ◽  
Jean-Louis Comlan Fannou ◽  
Clarence Guy Semassou ◽  
Malahimi Anjorin
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Effusivity ◽  
Volumetric Heat Capacity ◽  
Thermophysical Characteristics ◽  
Plane Method ◽  
Ornamental Stones ◽  
Thermophysical Characterization ◽  
Flooring Materials

This work aims to evaluate the thermophysical characteristics of local ornamental stones in order to facilitate their choice as efficient flooring materials. Methodology: Three varieties of the most known and requested ornamental stones on the market which include granite, marble and basalt extracted from the Beninese ground and subjected to asymmetric hot plane method to determine their thermal effusivity, thermal conductivity, thermal diffusivity and volumetric heat capacity. The parallelepiped-shaped samples of 10 cm × 10 cm × 3 cm were performed for measurements. The followings are the results of the different rocks studied: granite (3.220.01 W.m⎻1.K⎻1, 2470.510.006 J.m⎻1.K⎻1.s⎻1/2, 1.700.01μm².s⎻1, 1892.886.86 KJ.K⎻1.m⎻3); marble (4.940.02 W.m⎻1.K⎻1, 3416.340.009 J.m⎻1.K⎻1.s⎻1/2, 2.090.01 μm².s⎻1,  2362.737.90 KJ.K⎻1.m⎻3) and basalt (3.850.008 W.m⎻1.K⎻1, 2744.220.004 J.m⎻1.K⎻1.s⎻1/2, 1.9670.008 μm².s⎻1, 1956.494.07 KJ.K⎻1.m⎻3). Therefore granite is more insulating and marble has better ability to store heat.

scholarly journals Thermal Characterization of Phantoms Used for Quality Assurance of Deep Hyperthermia Systems

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4549
Author(s):  
Laura Farina ◽  
Kemal Sumser ◽  
Gerard van Rhoon ◽  
Sergio Curto
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Characterization ◽  
Sensitivity Study ◽  
Volumetric Heat Capacity ◽  
Internal Organs ◽  
Protocol Optimization ◽  
Thermal Measurements ◽  
Deep Hyperthermia

Tissue mimicking phantoms are frequently used in hyperthermia applications for device and protocol optimization. Unfortunately, a commonly experienced limitation is that their precise thermal properties are not available. Therefore, in this study, the thermal properties of three currently used QA phantoms for deep hyperthermia are measured with an “off-shelf” commercial thermal property analyzer. We have measured averaged values of thermal conductivity (k = 0.59 ± 0.07 Wm−1K−1), volumetric heat capacity (C = 3.85 ± 0.45 MJm−3K−1) and thermal diffusivity (D = 0.16 ± 0.02 mm2s−1). These values are comparable with reported values of internal organs, such as liver, kidney and muscle. In addition, a sensitivity study of the performance of the commercial sensor is conducted. To ensure correct thermal measurements, the sample under test should entirely cover the length of the sensor, and a minimum of 4 mm of material parallel to the sensor in all directions should be guaranteed.

Processing and thermal characteristics of human hair fiber-reinforced polymer composites

2019 ◽  
Vol 28 (4) ◽  
pp. 252-264
Author(s):  
Bishnu Prasad Nanda ◽  
Alok Satapathy
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Human Hair ◽  
Thermal Characteristics ◽  
Thermal Characterization ◽  
Fiber Reinforced Polymer Composites ◽  
Mathematical Correlation ◽  
Low Thermal Expansion ◽  
Hair Fiber

Human hair is a biofiber having an exceptional chemical composition, higher strength in tension, and slow decomposition rate. In the present work, composites are fabricated by simple hand layup technique with epoxy matrix and different proportions of hair fiber (0, 5, 10, 15, and 20 wt%). Physical, mechanical, microstructural, and thermal characterization of the composite samples has been done by following the proper ASTM standards. A theoretical model has been developed to predict the effective thermal conductivity of the composite. Based on this model, a mathematical correlation between the effective thermal conductivity of the composite and the fiber content is developed. The results obtained from this correlation are in good agreement with the experimental data. This study explores the possibility of fabricating a class of epoxy composites with higher mechanical strength, superior insulation capability, improved glass transition temperature, and a low thermal expansion coefficient.

scholarly journals Modeling of an Optically Heated MEMS-Based Micromechanical Bimaterial Sensor for Heat Capacitance Measurements of Single Biological Cells

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 215 ◽  
Author(s):  
Abdullah Alodhayb
Keyword(s):  
Heat Capacity ◽  
Thermal Characterization ◽  
Change Processes ◽  
Biological Cells ◽  
Deflection Curve ◽  
Measurement Capability ◽  
Real Time Measurement ◽  
Calorimetric Measurements ◽  
Highly Sensitive

Detection of thermal activities of biological cells is important for biomedical and pharmaceutical applications because these activities are closely associated with the conformational change processes. Calorimetric measurements of biological systems using bimaterial microcantilevers (BMC) have increasingly been reported with the ultimate goal of developing highly sensitive and inexpensive techniques with real-time measurement capability techniques for the characterization of dynamic thermal properties of biological cells. BMCs have been established as highly sensitive calorimeters for the thermal analysis of cells and liquids. In this paper, we present a simulation model using COMSOL Multiphysics and a mathematical method to estimate the heat capacity of objects (treated here as a biological cell) placed on the surface of a microcantilever. By measuring the thermal time constant, which is obtained from the deflection curve of a BMC, the heat capacity of a sample can be evaluated. With this model, we can estimate the heat capacity of single biological cells using a BMC, which can potentially be used for the thermal characterization of different biological samples.

scholarly journals Thermal characteristics study of light aggregate concrete of the middle Atlas pozzolana

2018 ◽  
Vol 149 ◽  
pp. 01033
Author(s):  
A. Bouyahyaoui ◽  
M. Cherkaoui ◽  
My L. Abidi ◽  
T. Cherradi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Experimental Study ◽  
Heat Capacity ◽  
Thermal Characteristics ◽  
Aggregate Concrete ◽  
Local Material ◽  
High Thermal Resistance ◽  
Middle Atlas

We present in this work an experimental study of the thermomechanical characterization of pozzolan (volcanic rock widespread in the region of Azrou in the Middle Atlas in Morocco). The objective of this work is to evaluate the effect of the pozzolan on the thermal conductivity of pozzolanic concrete by using different concrete formulations and this, by substituting various percentages of gravel and usual sands with gravel and sand of the pozzolan. The thermal properties of the samples consist to determine the thermal conductivity and the heat capacity. The results obtained show that the pozzolan is a local material with a high thermal resistance and can be used as a good insulated material in heat transfer and energy efficiency in the building.

scholarly journals Influence of Calcium Ions on the Thermal Characteristics of α-amylase from Thermophilic Anoxybacillus sp. GXS-BL

2019 ◽  
Vol 26 (2) ◽  
pp. 148-157 ◽  
Author(s):  
Si-Ming Liao ◽  
Ge Liang ◽  
Jing Zhu ◽  
Bo Lu ◽  
Li-Xin Peng ◽  
...  
Keyword(s):  
Calcium Ions ◽  
Thermal Denaturation ◽  
Thermal Inactivation ◽  
3D Structure ◽  
Thermal Characteristics ◽  
Thermal Characterization ◽  
Soluble Starch ◽  
Dsc Measurements ◽  
Irreversible Unfolding

Background: &#945;-Amylases are starch-degrading enzymes and used widely, the study on thermostability of &#945;-amylase is a central requirement for its application in life science and biotechnology. </P><P> Objective: In this article, our motivation is to study how the effect of Ca2+ ions on the structure and thermal characterization of &#945;-amylase (AGXA) from thermophilic Anoxybacillus sp.GXS-BL. </P><P> Methods: &#945;-Amylase activity was assayed with soluble starch as the substrate, and the amount of sugar released was determined by DNS method. For AGXA with calcium ions and without calcium ions, optimum temperature (Topt), half-inactivation temperature (T50) and thermal inactivation (halflife, t1/2) was evaluated. The thermal denaturation of the enzymes was determined by DSC and CD methods. 3D structure of AGXA was homology modeled with α-amylase (5A2A) as the template. </P><P> Results: With calcium ions, the values of Topt, T50, t1/2, Tm and &#916;H in AGXA were significantly higher than those of AGXA without calcium ions, showing calcium ions had stabilizing effects on &#945;-amylase structure with the increased temperature. Based on DSC measurements AGXA underwent thermal denaturation by adopting two-state irreversible unfolding processes. Based on the CD spectra, AGXA without calcium ions exhibited two transition states upon unfolding, including &#945;- helical contents increasing, and the transition from &#945;-helices to &#946;-sheet structures, which was obviously different in AGXA with Ca2+ ions, and up to 4 Ca2+ ions were located on the inter-domain or intra-domain regions according to the modeling structure. </P><P> Conclusion: These results reveal that Ca2+ ions have pronounced influences on the thermostability of AGXA structure.

Thermal and Physico-Mechanical Characterization of Paraíba’s State Soils to Applying in Soil-Cement Bricks

2008 ◽  
Vol 591-593 ◽  
pp. 532-536 ◽  
Author(s):  
Crislene Rodrigues da Silva Morais ◽  
Marcelo Rodrigues Leite ◽  
Luciana de Figueiredo L. Lucena ◽  
Railda Shelsea T. Rocha do Nascimento
Keyword(s):  
Building Materials ◽  
Thermal Characteristics ◽  
Decisive Role ◽  
Thermal Characterization ◽  
Additional Time ◽  
Soil Cement ◽  
Three Samples ◽  
Production Techniques ◽  
Negative Impacts

Soils play a decisive role in the manufacture of building materials, especially, tiles and bricks. Production techniques cause negative impacts on the environment and add additional time to the production process. Three samples obtained from Paraíba State were characterized by thermal characterization, granulometric and physical-mechanical techniques. Thermal analysis was undertaken in two different atmospheres, at a flow rate of 110 ml/min and a heating rate of 10oC/min. Evaluation of the soils through their thermal characteristics for use in soil-cement bricks production is elucidated.

scholarly journals Mechanical and thermal characterization of compact blocks made of clayey earth with wood ashes addition

2020 ◽  
Vol 307 ◽  
pp. 01030
Author(s):  
Gbénondé Sèna Gladys Milohin ◽  
Sènouhoua Victor Gbaguidi ◽  
André Donnot ◽  
Malahimi Anjorin ◽  
Riad Benelmir
Keyword(s):  
Building Materials ◽  
Variable Mass ◽  
Thermal Characteristics ◽  
Thermal Characterization ◽  
Mechanical Tests ◽  
Thermal Tests ◽  
Hot Strip ◽  
Simple Compression ◽  
French Association

The objective of this study is to evaluate the influence of wood ashes on the mechanical and thermal characteristics of the clayey earth-ashes compound (CEAC) compressed blocks. Variable mass percentages of 0% to 60% of wood ashes were incorporated to clayey earth stabilized with 10% of cement. The physical characteristics of the clayey earth were determined according to the protocols of the french association of normalization. The manufactured blocks were subjected to mechanical tests: simple compression and tensile by bending. The thermal conductivity was then appreciated by the method of the hot strip. The blocks made with a mixture of “90% clayey earth” and “10% cement”, usually used in construction in Benin, served as a reference material. From the results obtained, it appears that the clayey earth used is a soil A2ts: fine clayed sand in a very dry state. The results of the mechanical and thermal tests show that for an addition of wood ashes between 10% and 20% by weight, the performances of the blocks are significantly improved. The CEAC blocks formulated from 80% of the mixture “90% of clayey earth and 10% of cement” and 20% of wood ashes can be used as building materials.

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