scholarly journals Effect of Density and Fiber Size on Porosity and Thermal Conductivity of Fiberboard Mats

Fibers ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 81 ◽  
Author(s):  
Pamela Rebolledo ◽  
Alain Cloutier ◽  
Martin-Claude Yemele
Keyword(s):  
Thermal Conductivity ◽  
Medium Size ◽  
Fiber Mats ◽  
Black And White ◽  
Contrast Method ◽  
Fine Fiber ◽  
Fiber Size ◽  
Coarse Fibers ◽  
Mat Density ◽  
Porosity Measurements

The thermal conductivity and porosity of fiberboard mats are crucial parameters for efficient energy consumption of the hot-pressing process and for final panel quality. In this work, the effect of fiber size and mat density on porosity and thermal conductivity of the mat were investigated. The fiber size was characterized as fine, medium and coarse. The mat porosity was measured by image analysis using the black and white contrast method. The thermal conductivity was determined at different density levels with a temperature gradient of 1.6 °C mm−1 and 7.6% (s = 0.3) moisture content. The results showed that fiber size was a dominant variable governing heat conduction and mat porosity. The mats made with medium size fibers showed a higher resistance to compression. The thermal conductivity of coarse fiber mats decreased drastically between 700 kg m−3 and 810 kg m−3. This was likely due to a higher fracture frequency observed for coarse fibers in comparison to the other fiber sizes studied. Hence, the fine and medium fibers conducted heat more efficiently. Moreover, fiber bundles and fractured fibers were observed during the mat porosity measurements, principally in mats made with fine fiber size.

scholarly journals Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment

2009 ◽  
Vol 38 (11) ◽  
pp. 2218-2223 ◽  
Author(s):  
Alex Sandro Campos Maia ◽  
Roberto Gomes da Silva ◽  
João Batista Freire de Souza Junior ◽  
Rosiane Batista da Silva ◽  
Hérica Girlane Tertulino Domingos
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Free Convection ◽  
Effective Thermal Conductivity ◽  
Tropical Environment ◽  
Holstein Cows ◽  
Hair Coat ◽  
Black And White ◽  
Low K

The objective of the present study was to assess the effective thermal conductivity of the hair coat (k ef, mW.m-1.K-1) of Holstein cows in a tropical environment, as related to conduction and radiation in the absence of free convection. The average k ef was 49.72 mW.m-1.K-1, about twice the conductivity of the air (26 mW.m-1.K-1) and much less than that of the hair fibres (260 mW.m-1.K-1). The low k ef values were attributed mainly to the small cross area of individual hairs, ρef/ρf (17.2% and 21.3% for black and white hairs, respectively). White coats were denser, with longer hairs and significantly higher k ef (53.15 mW.m-1.K-1) than that of the black hairs (49.25 mW.m-1.K-1). The heritability coefficient of the effective thermal conductivity was calculated as h²=0.18 the possibility was discussed of selecting cattle for increased heat transfer through the hair coat.

Thermographic Studies of Aerogel Composites

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
K. Keerthi Sanghamitra ◽  
A. Yamini ◽  
A. Venu Vinod ◽  
Neha Hebalkar
Keyword(s):  
Thermal Conductivity ◽  
Silica Aerogel ◽  
Cold Water ◽  
High Porosity ◽  
Fiber Mats ◽  
Aerospace Applications ◽  
Thermal Insulating ◽  
Wide Range ◽  
Composite Form ◽  
Insulation Performance

AbstractAerogels are regarded as the superior thermal insulating materials for wide range of temperatures, from cryogenic insulation, cold water diving garments to high temperature applications and even to defense and aerospace applications. For most of such applications, the aerogels are used in composite form rather than monolithic form as aerogels are fragile in nature due to its high porosity of up to 98%. These composites constitute aerogel infiltrated fiber mats to give flexibility, on the other hand, compromises on the insulation performance due to reinforcing aerogel with fibers that have comparatively higher thermal conductivity than silica aerogel. To increase the efficiency, density of the fiber mat needs to be reduced to incorporate higher loading of silica aerogel. Many techniques are being used to study the insulation performance of these composites. This paper presents about the study of insulation performance of fibre mats with different aerogel content and composition using a well-known thermography technique. The morphological, compositional, thermal and physical studies of the fiber mats and its composites using FESEM, EDAX, BET, thermal conductivity etc., are discussed.

Aerial-photointerpretation of landslides along the Ohio and Mississippi rivers

2000 ◽  
Vol 6 (4) ◽  
pp. 311-323 ◽  
Author(s):  
Wen-June Su ◽  
Christopher Stohr
Keyword(s):  
Aerial Photography ◽  
Landslide Inventory ◽  
Medium Size ◽  
Airborne Radar ◽  
Seismic Zone ◽  
Southern Illinois ◽  
Medium Scale ◽  
Black And White ◽  
Field Reconnaissance ◽  
Low Altitude

Abstract A landslide inventory was conducted along the Ohio and Mississippi rivers in the New Madrid Seismic Zone of southern Illinois, between the towns of Olmsted and Chester, Illinois. Aerial photography and field reconnaissance identified 221 landslides of three types: rock/debris falls, block slides, and undifferentiated rotational/translational slides. Most of the landslides are small- to medium-size, ancient rotational/translational features partially obscured by vegetation and modified by weathering. Five imagery sources were interpreted for land-slides: 1:250,000-scale side-looking airborne radar (SLAR); 1:40,000-scale, 1:20,000-scale, 1:6,000-scale, black and white aerial photography; and low altitude, oblique 35-mm color photography. Landslides were identified with three levels of confidence on the basis of distinguishing characteristics and ambiguous indicators. SLAR imagery permitted identification of a 520 hectare mega-landslide which would not have been identified on medium-scale aerial photography. The leaf-off, 35-mm color, oblique photography provided the best imagery for confident interpretation of detailed features needed for smaller landslides.

Bone Marrow Reticulin in Patients with Immune Thrombocytopenic Purpura.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3982-3982 ◽  
Author(s):  
Ghulam Mufti ◽  
Adam Bagg ◽  
Robert Hasserjian ◽  
Barbara Bain ◽  
David Kuter ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Biopsy ◽  
Lupus Erythematosus ◽  
Immune Thrombocytopenic Purpura ◽  
Complete Blood Count ◽  
Thrombocytopenic Purpura ◽  
Fiber Network ◽  
Fine Fiber ◽  
Coarse Fibers ◽  
Clinical Records

Abstract Immune thrombocytopenic purpura (ITP) is an uncommon disorder, and research that characterizes the bone marrow stroma in ITP patients is lacking. It is known that megakaryocytes are often increased in number in ITP patients. Megakaryocytes are associated with reticulin formation in other conditions, including malignant and nonmalignant diseases, such as systemic lupus erythematosus and other immune disorders. Our objective was to determine if the reactive megakaryocyte proliferations in ITP are associated with increased reticulin deposition. We identified 40 ITP patients from clinical records in a retrospective survey of bone marrow biopsy material. Patients were required to have had a diagnosis of ITP, a bone marrow biopsy with available tissue blocks, and a complete blood count at the time of the biopsy. Paraffin-embedded sections from the bone marrow biopsy specimens were stained for reticulin using standard silver-impregnation methods. Reticulin was quantified using the Bauermeister scale (0 = no reticulin fibers demonstrable; 1 = occasional fine individual fibers and foci of a fine fiber network; 2 = fine fiber network throughout most of the section but no coarse fibers; 3 = diffuse fiber network with scattered thick coarse fibers but no mature collagen; and 4 = diffuse often coarse fiber network with areas of collagen). In addition, bone marrow cellularity and megakaryocyte numbers were evaluated. Of the 40 patients, 13 (33%) were considered to have absent (grade 0) bone marrow reticulin, 1 (2%) had grade 0–1, 20 (50%) had grade 1, 5 (13%) had grade 1–2, and 1 (2%) had grade 2. Thus, reticulin was present in the bone marrow of approximately two-thirds of the patients, with 15% having greater than grade 1. Previous research on bone marrow reticulin in 100 hematologically normal subjects found that 27% had Bauermeister reticulin grade 1 and 4% had grade 2 (Arch Pathol Lab Med1990;114:1241–3). Analysis is ongoing to further characterize the deposition of reticulin in the bone marrow of patients with ITP, the relationship of reticulin deposition to megakaryocyte numbers and location, and correlations with patient clinical findings.

The fast measurement of thermal conductivity for the refrigerant by the transient hot-wire contrast method

Cryogenics ◽  
1994 ◽  
Vol 34 ◽  
pp. 453-456
Author(s):  
Lie Xu ◽  
Shuliang Zhou ◽  
Jun Yang ◽  
Jun Ye ◽  
Liang Zhang
Keyword(s):  
Thermal Conductivity ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Fast Measurement ◽  
Contrast Method

The effect of different variables on in-plane radial permeability of natural fiber mats

2016 ◽  
Vol 37 (19) ◽  
pp. 1191-1201 ◽  
Author(s):  
Michael Ehresmann ◽  
Ali Amiri ◽  
Chad Ulven
Keyword(s):  
Fiber Volume Fraction ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Resin Transfer Molding ◽  
Limited Information ◽  
Fiber Volume ◽  
Fiber Mats ◽  
Transfer Molding ◽  
Fiber Size ◽  
Wax Content

There has been a vast growth in manufacturing of fiber reinforced plastics by means of liquid composite molding such as resin transfer molding and vacuum-assisted resin transfer molding processes. In these processes, compression of the porous media and pressure of the injected resin result in in-mold forces that need to be determined. Limited information exists regarding the processing parameters and extent of reinforcing potential natural fibers have in polymer matrices. Current study investigates the effect of different variables such as fiber volume fraction, shive content, fiber size, wax content, and resin viscosity on permeability of five different natural fiber mats. Flax fiber with low-, medium-, and high-shive content as well as hemp and kenaf fiber mats was selected for this study and an original experimental device was setup to measure the permeability of the mentioned fiber mats based on different variables. It was found that increasing fiber volume fraction will result in reduction of permeability of all mats. The presence of shive and larger fiber size increased the permeability. Higher wax content lowered the permeability. These competing factors could be used by manufacturers to produce a mat which had optimum permeability while still maintaining acceptable strength.

Pressure drop, penetration and quality factor of filter paper containing nanofibers

2016 ◽  
Vol 87 (4) ◽  
pp. 498-508 ◽  
Author(s):  
Min Tang ◽  
Jian Hu ◽  
Yun Liang ◽  
David YH Pui
Keyword(s):  
Pressure Drop ◽  
Quality Factor ◽  
Filter Paper ◽  
Modeling Method ◽  
Fibrous Structure ◽  
Fibrous Filter Media ◽  
Fine Fiber ◽  
Coarse Fibers ◽  
Filter Papers ◽  
Fiber Filter

Nanofiber has shown outstanding performance in many studies. Blending nanofibers into fibrous filter media is a promising way to improve the filtration performance. This paper discussed the modeling method for multi-fiber filter paper and the proper way to apply nanofiber into filter paper. Sixteen different filter papers were prepared and these filter papers covered the range of coarse-fiber-dominant and fine-fiber-dominant fibrous structure. The theoretical modeling method in this study for pressure drop and penetration of multi-fiber filter paper showed accurate results compared with the experiment data. It was found that for the higher quality factor, the nanofibers should be effectively separated by the coarse fibers. This study presented the idea of the fiber's effective contribution to filtration efficiency, which can lead to a comprehensive and distinct understanding of fibrous structure and filtration properties.

Preparation of ultra-fine fiber mats contained H4SiW12O40

2003 ◽  
Vol 6 (7) ◽  
pp. 916-918 ◽  
Author(s):  
Jian Gong ◽  
Chang-Lu Shao ◽  
Guo-Cheng Yang ◽  
Yan Pan ◽  
Lun-Yu Qu
Keyword(s):  
Fiber Mats ◽  
Fine Fiber
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