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101.
Detailed microstructural studies have been carried out on a series of composites consisting of Pyrex glass reinforced with Nicalon fibres. A variety of techniques has been employed, including X-ray and electron diffraction, electron-probe microanalysis and thin foil analytical electron microscopy. In parallel, mechanical tests have been performed on the composites and measurements have been made of the fibre-matrix bond.Substantial amounts of cristobalite have been identified in the matrix, up to 48% by volume in some cases. At such levels, microcracking is a common occurrence due to the high differential contraction between the matrix constituents upon cooling, which leads to matrix disintegration upon mechanical testing. A second microstructural feature which affects the mechanical behaviour of the composite concerns the fibre-matrix interface and, in particular, the chemistry of the outermost (200 nm) surface regions of the fibre. The amount of graphite here is shown to affect directly the strength of the fibre-matrix bond and, in turn, the degree of fibre pull out and the mechanical properties of the composite. 相似文献
102.
Keshun Liu Susan Seegers Wenming Cao Janitha Wanasundara Juxing Chen Alessandro Esteves da Silva Kristopher Ross Alexandra Lozano Franco Theo Vrijenhoek Pankaj Bhowmik Yonghui Li Xin Wu Scott Bloomer 《Journal of the American Oil Chemists' Society》2021,98(4):375-390
For determining trypsin inhibitor activity (TIA) in soy products, the American Oil Chemists' Society (AOCS) Method Ba 12-75 has been used. It measures differences in absorbance at 410 nm of bovine trypsin activity toward a synthetic substrate (Nα-benzoyl-DL-arginine-p-nitroanilide) in the absence and presence of an inhibitor. Recently, a significantly improved method was developed (JAOCS, 2019, 96:635–645), featuring 5 mL of total assay volume, enzyme-last sequence, and single inhibitor level in duplicate. It is proposed as the AOCS Method Ba 12a-2020. As a part of the AOCS method approval process, a collaborative study involving 12 international laboratories was conducted to evaluate the performance of the proposed method. The study involved measuring TIA in 10 selected test samples plus a blind duplicate. They included soybeans, pulses, cereals, and their processed products (flours, concentrates, and isolates). After rigorous statistical treatment of the data, only three outliers were removed from the data of two samples. Repeatability relative standard deviations (RSDr) for the 11 samples ranged from 0.99% to 5.52%. Reproducibility RSD (RSDR) ranged from 7.07% to 22.92%, with seven samples having RSDR around 10% or less. The remaining four samples had very low TIA, and their RSDR values ranged from 13.34% to 22.92%. The study has demonstrated reliable performance of the proposed AOCS method. Several collaborators carried out additional experiments addressing some aspects of the method, leading to further refinements. The proposed method is undergoing evaluation by the AOCS Uniform Methods Committee for adoption as an Official Method for measuring TIA in various legume and grain products. 相似文献
103.
Sputtered Ni + TiB2 coatings have been shown to protect Inconel* 718 and Ti-6A1-4V substrates from solid particle erosion. However, before new
erosion-resistant coatings can be efficiently designed, it is essential that the role of mechanical properties in determining
erosion resistance be fully understood. In this investigation, nanoindentation techniques were used to quantify the effects
of substrate preparation, coating composition, and sputtering process parameters on the elastic moduli and indentation hardness
of thin coatings deposited on Ti-6A1-4V and Inconel 718 substrates. The influence of these parameters on coating adhesion
was determined using a conventional scratch test. Elastic moduli, indentation hardnesses, and coating adhesion were correlated
with erosion behavior. The erosion resistance of those coatings that exhibited microscopic ductility is dependent on the nodule
diameter and coating properties such as hardness, elastic modulus, and fracture toughness.
Inconel 718 is a trademark of The International Nickel Co. 相似文献
104.
This article summarizes the results of Executive Perspectives on Top Risks for 2015, a study conducted by North Carolina State University’s ERM Initiative and Protiviti. For more information, visit www.protiviti.com/TopRisks. 相似文献
105.
106.
Bethany Anderson Fynnette Eaton Scott W. Schwartz 《New Review of Information Networking》2015,20(1-2):3-15
The digital revolution has changed the daily work of archivists. As a result, archivists have refined their analog practices and initiated new ones to accommodate the unique information creation and access needs of users. While limitless storage and technological obsolescence may be surmountable challenges, appraisal continues to be a necessary component of this preservation enterprise. Macro-appraisal—a top-down functional assessment of an organization’s high-level decision making that defines the enduring value of specific bodies of documentary evidence of these creative or administrative processes—is used to facilitate the management of diverse bodies of born-digital records in archives and special collections. 相似文献
107.
Sez Atamturktur Zhifeng Liu Scott Cogan Hsein Juang 《Structural and Multidisciplinary Optimization》2015,51(3):659-671
Traditionally, model calibration is formulated as a single objective problem, where fidelity to measurements is maximized by adjusting model parameters. In such a formulation however, the model with best fidelity merely represents an optimum compromise between various forms of errors and uncertainties and thus, multiple calibrated models can be found to demonstrate comparable fidelity producing non-unique solutions. To alleviate this problem, the authors formulate model calibration as a multi-objective problem with two distinct objectives: fidelity and robustness. Herein, robustness is defined as the maximum allowable uncertainty in calibrating model parameters with which the model continues to yield acceptable agreement with measurements. The proposed approach is demonstrated through the calibration of a finite element model of a steel moment resisting frame. 相似文献
108.
Rick Sobiesiak Robert J. Jones Scott M. Lewis 《International journal of human-computer interaction》2013,29(3-4):279-306
This case study describes the application of user-centered design (UCD) principles to the development of a complex middleware software product-IBM's DB2(r) Universal Database. Motivated by trade press reviews highlighting ease-of-use problems, a multisite development team utilized IBM UCD to transform ease of use into a featured product attribute. This case study describes the initial application of UCD to DB21 and the positive business results that followed: critical acclaim, increased marketshare and user satisfaction, and increased support and adoption of UCD across the IBM database product family. Although ease-of-use objectives, target markets, and human factors practitioners' roles have evolved over 6 years and multiple versions of the product, DB2 continues to achieve positive results with UCD. In addition to the flexibility of the UCD methodology, other factors that influenced DB2's success included management support, resource commitment, cross-site communication and collaboration, detailed product specifications, and a focus on supporting user tasks. 相似文献
109.
TeraGrid Science Gateways and Their Impact on Science 总被引:1,自引:0,他引:1
Wilkins-Diehr Nancy Gannon Dennis Klimeck Gerhard Oster Scott Pamidighantam Sudhakar 《Computer》2008,41(11):32-41
The Science Gateways program seeks to provide researchers with easy access to TeraGrid's high-performance computing resources. A look at four successful gateways illustrates the program's goals, challenges, and opportunities. 相似文献
110.
Matthew?L.?StatenEmail author Steven?Benzley Michael?Scott 《Engineering with Computers》2008,24(3):241-251
High fidelity finite element modeling of continuum mechanics problems often requires using all quadrilateral or all hexahedral
meshes. The efficiency of such models is often dependent upon the ability to adapt a mesh to the physics of the phenomena.
Adapting a mesh requires the ability to both refine and/or coarsen the mesh. The algorithms available to refine and coarsen
triangular and tetrahedral meshes are very robust and efficient. However, the ability to locally and conformally refine or
coarsen all quadrilateral and all hexahedral meshes presents many difficulties. Some research has been done on localized conformal
refinement of quadrilateral and hexahedral meshes. However, little work has been done on localized conformal coarsening of
quadrilateral and hexahedral meshes. A general method which provides both localized conformal coarsening and refinement for
quadrilateral meshes is presented in this paper. This method is based on restructuring the mesh with simplex manipulations
to the dual of the mesh. In addition, this method appears to be extensible to hexahedral meshes in three dimensions.
Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the
United States Department of Energy under Contract DE-AC04-94AL85000. 相似文献