Fundamental Issues in the Sintering of Ceramic Particulate Composites

1991 ◽  
Vol 249 ◽  
Author(s):  
Mohamed N. Rahaman
Keyword(s):  
Ceramic Powder ◽  
Particulate Composites ◽  
Full Density ◽  
Volume Percent ◽  
Ceramic Particulate ◽  
Two Factors ◽  
The Matrix ◽  
Coated Inclusion ◽  
The Subject ◽  
Main Factors

ABSTRACTThe sintering rate of a ceramic powder matrix can be reduced significantly by the presence of rigid inclusions. The factors that lead to this reduced sinterability have been the subject of much debate in the last 5–10 years. Recent work indicate that the reduction in the matrix sinterability is a processing-related problem. The main factors that control the sinterability of ceramic particulate composites include the packing of the matrix immediately surrounding the inclusions and interactions between the inclusions which constrain the matrix. A processing method which avoids the difficulties associated with these two factors is outlined. The method involves the synthesis of coated inclusion particles. Composites containing up to 40 volume percent inclusions can be freely sintered in the solid state to full density.

Factor Analysis of Underestimation for the Russian Companies IPO

2017 ◽  
Vol 2017 (4) ◽  
pp. 29-51
Author(s):  
Varvara Nazarova
Keyword(s):  
Factor Analysis ◽  
Information Asymmetry ◽  
Host Country ◽  
Significant Influence ◽  
Ipo Underpricing ◽  
Two Factors ◽  
The Subject ◽  
Main Factors

The problem of IPO underpricing became relevant in the late 1960s. Since then various theories were advanced connecting this phenomenon to many factors: from information asymmetry in the market to the cultural peculiarities of the host country. The article aims to identify factors that have a significant influence on the occurrence and magnitude of underpricing of shares in Russian companies preparing their IPOs. Research and theories of foreign and Russian authors devoted to the subject were analyzed, which uncovered 7 main factors, which are further considered in terms of their influence on the occurrence and magnitude of underpricing. To test the hypotheses, data for 138 IPOs of Russian companies for 1996-2015 was collected. Analysis showed that two factors influence the occurrence and the magnitude of the underpricing of Russian companies’ IPOs: the amount of accommodation and the provision of accommodation prices in the price corridor, announced by the company. In conclusion, recommendations for Russian issuers on the formation of the strategies of the IPO are made.

Microdiffraction analysis of precipitate crystallography and morphology in Al alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 954-955
Author(s):  
B.C. Muddle ◽  
G.R. Hugo
Keyword(s):  
Point Group ◽  
Hexagonal Lattice ◽  
Intersection Point ◽  
Saed Pattern ◽  
Point Symmetry ◽  
Hexagonal Symmetry ◽  
Precipitate Crystal ◽  
The Matrix ◽  
The Subject ◽  
Electron Microdiffraction

Electron microdiffraction has been used to determine the crystallography of precipitation in Al-Cu-Mg-Ag and Al-Ge alloys for individual precipitates with dimensions down to 10 nm. The crystallography has been related to the morphology of the precipitates using an analysis based on the intersection point symmetry. This analysis requires that the precipitate form be consistent with the intersection point group, defined as those point symmetry elements common to precipitate and matrix crystals when the precipitate crystal is in its observed orientation relationship with the matrix.In Al-Cu-Mg-Ag alloys with high Cu:Mg ratios and containing trace amounts of silver, a phase designated Ω readily precipitates as thin, hexagonal-shaped plates on matrix {111}α planes. Examples of these precipitates are shown in Fig. 1. The structure of this phase has been the subject of some controversy. An SAED pattern, Fig. 2, recorded from matrix and precipitates parallel to a <11l>α axis is suggestive of hexagonal symmetry and a hexagonal lattice has been proposed on the basis of such patterns.

scholarly journals Predictive Computational Model for Damage Behavior of Metal-Matrix Composites Emphasizing the Effect of Particle Size and Volume Fraction

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2143
Author(s):  
Shaimaa I. Gad ◽  
Mohamed A. Attia ◽  
Mohamed A. Hassan ◽  
Ahmed G. El-Shafei
Keyword(s):  
Finite Element ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Particulate Composites ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Zone Method ◽  
Stress Strain ◽  
The Matrix

In this paper, an integrated numerical model is proposed to investigate the effects of particulate size and volume fraction on the deformation, damage, and failure behaviors of particulate-reinforced metal matrix composites (PRMMCs). In the framework of a random microstructure-based finite element modelling, the plastic deformation and ductile cracking of the matrix are, respectively, modelled using Johnson–Cook constitutive relation and Johnson–Cook ductile fracture model. The matrix-particle interface decohesion is simulated by employing the surface-based-cohesive zone method, while the particulate fracture is manipulated by the elastic–brittle cracking model, in which the damage evolution criterion depends on the fracture energy cracking criterion. A 2D nonlinear finite element model was developed using ABAQUS/Explicit commercial program for modelling and analyzing damage mechanisms of silicon carbide reinforced aluminum matrix composites. The predicted results have shown a good agreement with the experimental data in the forms of true stress–strain curves and failure shape. Unlike the existing models, the influence of the volume fraction and size of SiC particles on the deformation, damage mechanism, failure consequences, and stress–strain curve of A359/SiC particulate composites is investigated accounting for the different possible modes of failure simultaneously.

scholarly journals The Influence of Filler Size and Crosslinking Degree of Polymers on Mullins Effect in Filled NR/BR Composites

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2284
Author(s):  
Miaomiao Qian ◽  
Bo Zou ◽  
Zhixiao Chen ◽  
Weimin Huang ◽  
Xiaofeng Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Strain Energy ◽  
Mathematical Expression ◽  
Rubber Matrix ◽  
Mullins Effect ◽  
Butadiene Rubber ◽  
Crosslinking Degree ◽  
Test Range ◽  
Two Factors ◽  
The Matrix

Two factors, the crosslinking degree of the matrix (ν) and the size of the filler (Sz), have significant impact on the Mullins effect of filled elastomers. Herein, the result. of the two factors on Mullins effect is systematically investigated by adjusting the crosslinking degree of the matrix via adding maleic anhydride into a rubber matrix and controlling the particle size of the filler via ball milling. The dissipation ratios (the ratio of energy dissipation to input strain energy) of different filled natural rubber/butadiene rubber (NR/BR) elastomer composites are evaluated as a function of the maximum strain in cyclic loading (εm). The dissipation ratios show a linear relationship with the increase of εm within the test range, and they depend on the composite composition (ν and Sz). With the increase of ν, the dissipation ratios decrease with similar slope, and this is compared with the dissipation ratios increase which more steeply with the increase in Sz. This is further confirmed through a simulation that composites with larger particle size show a higher strain energy density when the strain level increases from 25% to 35%. The characteristic dependence of the dissipation ratios on ν and Sz is expected to reflect the Mullins effect with mathematical expression to improve engineering performance or prevent failure of rubber products.

A Novel Coreflood Test to Evaluate EOR Potential of Wettability-Altering Surfactants in Oil-Wet Heterogeneous Carbonate Reservoirs

2021 ◽  
Author(s):  
Yue Shi ◽  
Kishore Mohanty ◽  
Manmath Panda
Keyword(s):  
Oil Recovery ◽  
Carbonate Reservoirs ◽  
Wettability Alteration ◽  
Low Permeability ◽  
High Permeability ◽  
Matrix Permeability ◽  
Rock Heterogeneity ◽  
The Matrix ◽  
Flow Through ◽  
Main Factors

Abstract Oil-wetness and heterogeneity (i.e., existence of low and high permeability regions) are two main factors that result in low oil recovery by waterflood in carbonate reservoirs. The injected water is likely to flow through high permeability regions and bypass the oil in low permeability matrix. In this study, systematic coreflood tests were carried out in both "homogeneous" cores and "heterogeneous" cores. The heterogeneous coreflood test was proposed to model the heterogeneity of carbonate reservoirs, bypassing in low-permeability matrix during waterfloods, and dynamic imbibition of surfactant into the low-permeability matrix. The results of homogeneous coreflood tests showed that both secondary-waterflood and secondary-surfactant flood can achieve high oil recovery (&gt;50%) from relatively homogenous cores. A shut-in phase after the surfactant injection resulted in an additional oil recovery, which suggests enough time should be allowed while using surfactants for wettability alteration. The core with a higher extent of heterogeneity produced lower oil recovery to waterflood in the coreflood tests. Final oil recovery from the matrix depends on matrix permeability as well as the rock heterogeneity. The results of heterogeneous coreflood tests showed that a slow surfactant injection (dynamic imbibition) can significantly improve the oil recovery if the oil-wet reservoir is not well-swept.

Partial Color Constancy of Isolated Surface Colors Examined by a Color-Naming Method

Perception ◽  
1989 ◽  
Vol 18 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Keiji Uchikawa ◽  
Hiromi Uchikawa ◽  
Robert M Boynton
Keyword(s):  
Color Constancy ◽  
Color Naming ◽  
The State ◽  
Color Appearance ◽  
Chromatic Adaptation ◽  
Light Sources ◽  
Two Factors ◽  
The Subject ◽  
Spectral Distributions ◽  
Color Scales

Color samples selected from the OSA Uniform Color Scales set were viewed without any surround. Separate light sources were used to illuminate the samples and to control the state of adaptation of the subject, thereby separating two factors that are normally confounded. A color-naming procedure was used to assess shifts in color appearance produced by altering the spectral distributions of one or both light sources. The results confirm that chromatic adaptation, when it is the only factor operating, can mediate partial color constancy.

scholarly journals Featural definition of syntactic positions: Evidence from hyper-raising

2018 ◽  
Vol 3 (1) ◽  
pp. 2 ◽  
Author(s):  
Suzana Fong
Keyword(s):  
Phase Problem ◽  
Matrix Clause ◽  
The Matrix ◽  
The Subject ◽  
Embedded Clause ◽  
Definition Of ◽  
Finite Clause

Hyper-raising consists in raising a DP from an embedded finite clause into the matrix clause. HR introduces a phase problem: the embedded clause is finite, which is supposed to be impervious to raising. This can be overcome by postulating A-features at the C of the the embedded clause. They trigger the movement of the subject to [Spec, CP]. Being at the edge of a phase, it is visible to a matrix probe. If successful, this analysis provides support for the claim that syntactic positions are not inherently A or A-bar; they can be defined featurally instead.

scholarly journals PENGALAMAN BERLITERASI PENULIS DI KOTA BANDUNG DALAM PEMERTAHANAN BUDAYA LOKAL SUNDA

Jurnal Signal ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 49
Author(s):  
Santi Susanti ◽  
Kokom Komariah
Keyword(s):  
Qualitative Method ◽  
Social Problems ◽  
Phenomenological Approach ◽  
Cultural Preservation ◽  
Reading Habits ◽  
The Subject ◽  
Main Factors ◽  
Depth Interviews ◽  
Classical History

Penelitian ini bertujuan untuk menggambarkan pengalaman berliterasi penulis di Kota Bandung dalam menjalani perannya sebagai penulis Sunda.Pokok bahasan yang digali meliputi aspek pendorong menjadi penulis Sunda, pilihan jenis dan tema tulisan untuk menyampaikan perasaan dan pikiran penulis, serta aspek harapan dalam menjalani peran sebagai penulis Sunda.Metode kualitatif dengan pendekatan fenomenologi digunakan untuk menguraikan pengalaman pada penulis Sunda dalam berliterasi. Wawancara mendalam dan penelusuran literatur digunakan untuk memperoleh data dari 8 penulis yang menjadi informan penelitian ini. Hasil studi menunjukkan, lingkungan dan kebiasaan membaca menjadi faktor utama yang mendorong penulis untuk menulis dalam bahasa Sunda. Tulisan fiksi dan nonfiksi menjadi pilihan penulis untuk menyampaikan pikiran dan perasannya melalui tulisan. Masalah sosial, sejarah klasik Sunda, kearifan lokal, humor, dan peristiwa aktual menjadi pilihan tema dalam tulisan para informan. Adapun yang menjadi aspek harapan sebagai penulis Sunda adalah memelihara keberlangsungan bahasa Sunda, serta berharap dapat membawa budaya Sunda ke peradaban global. Kata kunci: Literasi, Budaya Sunda, Penulis Sunda, Pelestarian Budaya ABSTRACTThis research aims to describe the author's experience in doing literacy as a Sundanese writer in Bandung City. The subject explored includes the driving aspects of being a Sundanese writer, choice of types and themes of writing, as well as aspects of hope in carrying out the role as a Sundanese writer. The qualitative method with a phenomenological approach is used to describe the experience of Sundanese writers in literacy. In-depth interviews and literature were used to obtain data from 8 writers who became informants of this study. The result shows that environment and reading habits are the main factors that encourage writers to write in the Sundanese language. Fiction and nonfiction literature contents are used to convey a writer’s thoughts and feelings through writing. Social problems, Sundanese classical history, local wisdom, humor, and actual events are the themes in the informants' writings. The aspect of hope as a Sundanese writer is to maintain the continuity of Sundanese language, and hope to bring Sundanese culture to global civilization.Keywords: Literacy, Sundanese Culture, Sundanese Writers, Cultural Preservation

scholarly journals Economic and IT determinants of innovative projects in the textiles, wearing apparel, leather and related products industry

2018 ◽  
Vol 69 (04) ◽  
pp. 338-344
Author(s):  
SIMION CEZAR-PETRE ◽  
ALEXANDRU ADRIANA ◽  
CEPTUREANU SEBASTIAN ION ◽  
CEPTUREANU EDUARD GABRIEL
Keyword(s):  
European Union ◽  
Correlation Analysis ◽  
Volume Index ◽  
Major Influence ◽  
Factors Influencing ◽  
Global Demand ◽  
Two Factors ◽  
Main Factors ◽  
Potential Factors

In this paper the main factors that influence the innovative projects in the field of textiles, wearing apparel, leather and related products were identified and analyzed. Eleven potential factors influencing innovative projects have been considered and the correlation analysis has identified the two factors that have a major influence on innovative projects in the field: volume index of production in European Union for NACE codes 13-15 and exports value for textiles, wearing apparel, leather and related products. The research has shown that the scale of innovative projects in textiles, clothing, leather and related products depends on European Union production and on global demand.

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