New Composite Metal Foams under Compressive Cyclic Loadings

2007 ◽  
Vol 539-543 ◽  
pp. 1868-1873 ◽  
Author(s):  
Afsaneh Rabiei ◽  
Brian Neville ◽  
Nick Reese ◽  
Lakshmi Vendra
Keyword(s):  
Maximum Stress ◽  
Cell Structure ◽  
Hollow Spheres ◽  
Metal Foams ◽  
Entire Sample ◽  
Gravity Casting ◽  
Cyclic Compression ◽  
High Maximum ◽  
Processing Techniques ◽  
Very High

New composite metal foams are processed using powder metallurgy (PM) and gravity casting techniques. The foam is comprised of steel hollow spheres, with the interstitial spaces occupied by a solid metal matrix (Al or steel alloys). The cyclic compression loading of the products of both techniques has shown that the composite metal foams have high cyclic stability at very high maximum stress levels up to 68 MPa. Under cyclic loading, unlike other metal foams, the composite metal foams do not experience rapid strain accumulation within collapse bands and instead, a uniform distribution of deformation happen through the entire sample until the densification strain is reached. This is a result of more uniform cell structure in composite metal foams compared to other metal foams. As a result, the features controlling the fatigue life of the composite metal foams have been considered as sphere wall thickness and diameter, sphere and matrix materials, and processing techniques as well as bonding strength between the spheres and matrix.

scholarly journals IDENTIFICATION OF MEGALOBLASTIC ANEMIA CELLS THROUGH THE USE OF IMAGE PROCESSING TECHNIQUES

2018 ◽  
Vol 4 (3) ◽  
pp. 1-5 ◽  
Author(s):  
Asaad Babker ◽  
Vyacheslav Lyashenko
Keyword(s):  
Image Processing ◽  
Image Analysis ◽  
Blood Smear ◽  
Color Image ◽  
Megaloblastic Anemia ◽  
Cell Structure ◽  
Color Space ◽  
Image Processing Techniques ◽  
Processing Techniques ◽  
Blood Smear Image

Objective: Our aim is to show the possibility of using different image processing techniques for blood smear analysis. Also our aim is to determine the sequence of image processing techniques to identify megaloblastic anemia cells. Methods: We consider blood smear image. We use a variety of image processing techniques to identify megaloblastic anemia cells. Among these methods, we distinguish the modification of the color space and the use of wavelets. Results: We developed a sequence of image processing techniques for blood smear image analysis and megaloblastic anemia cells identification. As a characteristic feature for megaloblastic anemia cells identification, we consider neutrophil image structure. We also use the morphological methods of image analysis in order to reveal the nuclear lobes in neutrophil structure. Conclusion: We can identify the megaloblastic anemia cells. To do this, we use the following sequence of blood smear image processing: color image modification, change of the image contrast, use of wavelets and morphological analysis of the cell structure. 

Porous mullite ceramics with a fully closed-cell structure fabricated by direct coagulation casting using fly ash hollow spheres/kaolin suspension

2020 ◽  
Vol 46 (11) ◽  
pp. 17508-17513
Author(s):  
Shuang Chen ◽  
Wei-Hao Cai ◽  
Jia-Min Wu ◽  
Yi-Xin Ma ◽  
Chen-Hui Li ◽  
...  
Keyword(s):  
Fly Ash ◽  
Cell Structure ◽  
Hollow Spheres ◽  
Kaolin Suspension ◽  
Closed Cell ◽  
Porous Mullite ◽  
Mullite Ceramics

Synthesis and Properties of Open-Celled Metal Foams

2007 ◽  
Vol 534-536 ◽  
pp. 1005-1008 ◽  
Author(s):  
Peter Quadbeck ◽  
Günther Stephani ◽  
Kerstin Kümmel ◽  
Joerg Adler ◽  
Gisela Standke
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Cell Size ◽  
Significant Influence ◽  
Cell Structure ◽  
Metal Foams ◽  
Compression Tests ◽  
Stainless Steel 316L ◽  
Replication Technique ◽  
Highly Porous

Open-celled metal foams were synthesized using a replication technique. Therefore a reticulated polyurethane template was coated by a slurry and removed thermally, followed by a sintering step. Since the process is feasible for a multiplicity of metals the experiments were performed on the example of stainless steel 316L. Highly porous components were obtained showing adjustable densities between 0.3 and 2.0 g/cm³. The cell structure is exceedingly homogeneous and the cell sizes may be chosen in the range of 10 – 80 ppi. In order to characterise the properties, compression tests and acoustical tests were carried out. A significant influence of the density and the cell size on the acoustical and mechanical properties was noticed.

A driving cycle for electrically-driven vehicles in Rome

2003 ◽  
Vol 217 (9) ◽  
pp. 781-789 ◽  
Author(s):  
A Alessandrini ◽  
F Orecchini
Keyword(s):  
Electric Vehicle ◽  
Driving Cycle ◽  
The Other ◽  
Maximum Speed ◽  
Electric Cars ◽  
High Maximum ◽  
Big City ◽  
Limited Power ◽  
The City ◽  
Very High

In the research results presented here, an average driving cycle is synthesized for an electrically driven car moving in the city of Rome. The technique of Lyons et al. [1] for synthesizing a statistically representative driving cycle was used on a 5 week acquisition set of data collected with a duly equipped electric Citroen Saxo that was driven for over 3100 km by six different drivers in the months of May and June 2001 in Rome. The driving cycle developed is compared with the other available cycles, especially the European ones. The comparison highlights the need for this new dedicated cycle to represent the driving conditions of electric cars in Rome, with a lower value of the acceleration-speed product on account of the limited power of the electric vehicle, frequent changes in the acceleration sign, typical of the trafic in a big city, and a very high maximum speed, typical of the driving behaviour of the inhabitants of Rome.

scholarly journals Preparation, microstructure studies and mechanical properties of glazes ceramic sanitary ware based on kaolin

2021 ◽  
Vol 53 (2) ◽  
pp. 209-221
Author(s):  
Samra Benkacem ◽  
Kamel Boudeghdegh ◽  
Fouzia Zehani ◽  
Mohamed Hamidouche ◽  
Youghourta Belhocine
Keyword(s):  
Vickers Microhardness ◽  
Sanitary Ware ◽  
X Ray Diffraction ◽  
Water Absorption Coefficient ◽  
X Ray ◽  
Glazed Ceramic ◽  
Processing Techniques ◽  
Very High ◽  
Conventional Ceramic Processing ◽  
Potential Use

In this paper, the use of local kaolin coming from Djebel Debbagh (denoted DD1) in the composition of ceramic glazes for sanitary ware was examined. Because of its natural abundance, low price and good characteristics, this kaolin represents an interesting economic alternative to other mineral clays. The chemical composition showed that this kaolin contains 38.49 wt.% Al2O3 and 44.85 wt.% SiO2. Two glazes based on kaolin DD1 denoted as GaDD1 and GbDD1 were prepared with conventional ceramic processing techniques at temperature 1250 oC. As a reference, another glaze (Gref) based on kaolin Remblend was also prepared in the same conditions. The samples were characterized with X-ray diffraction and Scanning Electron Microscope. The results revealed that zircon and quartz are the crystalline phases present in these glazes. In the sample GaDD1, it was found that the degree of whiteness is very high and reaches 93.30 %. However, the water absorption coefficient is low which is about 0.19 ? 0.04 %. In addition, the flexural strength and the Vickers microhardness are respectively, about 56.07 ? 5.61 MPa and 7952.80 ? 101.76 MPa. These properties are compatible with those of the glaze reference Gref and commercial sanitary ware glazes, indicating the potential use of kaolin DD1 in the production of glazed ceramic for sanitary ware applications.

scholarly journals Preserving surface area and porosity during fabrication of silicon aerocrystal particles from anodized wafers

2020 ◽  
Author(s):  
C. J. Storey ◽  
E. Nekovic ◽  
A. Kaplan ◽  
W. Theis ◽  
L. T. Canham
Keyword(s):  
Porous Silicon ◽  
Ball Milling ◽  
Surface Area ◽  
Mechanical Milling ◽  
High Surface ◽  
High Porosity ◽  
Processing Times ◽  
Surface Areas ◽  
Processing Techniques ◽  
Very High

Abstract Porous silicon layers on wafers are commonly converted into particles by mechanical milling or ultrasonic fragmentation. The former technique can rapidly generate large batches of microparticles. The latter technique is commonly used for making nanoparticles but processing times are very long and yields, where reported, are often very low. With both processing techniques, the porosity and surface area of the particles generated are often assumed to be similar to those of the parent film. We demonstrate that this is rarely the case, using air-dried high porosity and supercritically dried aerocrystals as examples. We show that whereas ball milling can more quickly generate much higher yields of particles, it is much more damaging to the nanostructures than ultrasonic fragmentation. The latter technique is particularly promising for silicon aerocrystals since processing times are reduced whilst yields are simultaneously raised with ultrahigh porosity structures. Not only that, but very high surface areas (> 500 m2/g) can be completely preserved with ultrasonic fragmentation.

scholarly journals Structural Damages in Syntactic Metal Foams Caused by Monotone or Cyclic Compression

2017 ◽  
Vol 61 (2) ◽  
pp. 146 ◽  
Author(s):  
Bálint Katona ◽  
Imre Norbert Orbulov
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Metal Matrix ◽  
High Strain ◽  
Hollow Spheres ◽  
Syntactic Foams ◽  
Pressure Infiltration ◽  
Cyclic Compression ◽  
Significant Difference ◽  
Strain Rate Compression

Closed cell, high strength metallic foams, like ceramic hollow spheres filled metal matrix foams are promising materials to build lightweight but high specific strength structural parts. The aim of this study is to investigate the damage of the foam structure during monotone or cyclic compression. The tested metal matrix syntactic foams were produced by inert gas pressure infiltration. Four different alloys as matrix and two different ceramic hollow spheres as filler material were applied. The cylindrical specimens were investigated in quasi-static and high strain rate compression and in cyclic compression. The higher strain rates were ensured by a Split-Hopkinson pressure bar system, while the fatigue tests were performed on a closed loop universal hydraulic testing machine. The failure modes of the foams have explicit differences showing barreling and shearing in the case of quasi-static and high strain rate compression respectively. In the case of the fatigue loading, there was a significant difference between the damage mechanisms of the unalloyed and the Si alloyed matrix syntactic foams. This can be explained by the difference between the yield strength of the matrix material and the ceramics hollow spheres.

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