The reverse analysis provides a convenient method to determine four elastic-plastic parameters through an indentation curve such as Young s modulus E, hardness H, yield strength σy and strain hardening exponent n. In...
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The reverse analysis provides a convenient method to determine four elastic-plastic parameters through an indentation curve such as Young s modulus E, hardness H, yield strength σy and strain hardening exponent n. In this paper, mathematical analysis on a reverse algorithm from Dao model （Dao et al., Acta Mater., 2001, 49, 3899） was carried out, which thought that only when 20 ≤E＊/σ0.033≤ 26 and 0.3n≤ 0.5, the reverse algorithm would yield two solutions of n by dimensionless function Π2. It is shown that, however, there are also two solutions of n when 20≤E＊/σ0.033≤ 26 and 0≤n0.1. A unique n can be obtained by dimensionless function Π3 instead of Π2 in these two ranges. E and H can be uniquely determined by a full indentation curve, and σy can be determined if n is unique. Furthermore, sensitivity analysis on obtaining n from dimensionless function Π3 or Π2 has been made.
Syphilis, caused by the bacterium Treponema pallidum subsp. pallidum, is an infection recognized since antiquity. It was first reported at the end of the 15th century in Europe. Infections may be sexually transmitted ...
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Syphilis, caused by the bacterium Treponema pallidum subsp. pallidum, is an infection recognized since antiquity. It was first reported at the end of the 15th century in Europe. Infections may be sexually transmitted as well as spread from an infected mother to her fetus or through blood transfusions. The laboratory diagnosis of syphilis infection is complex. Because this organism cannot be cultured, serology is used as the principal diagnostic method. Some of the issues related to serological diagnoses are that antibodies take time to appear after infection, and serology screening tests require several secondary confirmatory tests that can produce complex results needing interpretation by experts in the field. Traditionally, syphilis screening was performed using either rapid plasma reagin or Venereal Disease Research Laboratory tests, and confirmed by treponemal tests such as MHA-TP, TPPA or FTA-Abs. Currently, that trend is reversed, ie, most of the laboratories in Canada now screen for syphilis using treponemal enzyme immunoassays and confirm the status of infection using rapid plasma reagin or Venereal Disease Research Laboratory tests;this approach is often referred to as the reverse algorithm. This chapter reviews guidelines for specimen types and sample collection, treponemal and non-treponemal tests utilized in Canada, the current status of serological tests for syphilis in Canada, the complexity of serological diagnosis of syphilis infection and serological testing algorithms. Both traditional and reverse sequence algorithms are recommended and the algorithm used should be based on a combination of local disease epidemiology, test volumes, performance of the proposed assays and available resources.
Background: Treponemal tests for detecting syphilis should be sufficiently sensitive and specific, especially when used as the first-line method in reverse-algorithm testing. We compared the Siemens ADVIA Centaur (R) ...
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Background: Treponemal tests for detecting syphilis should be sufficiently sensitive and specific, especially when used as the first-line method in reverse-algorithm testing. We compared the Siemens ADVIA Centaur (R) Syphilis assay to 2 other commercial assays in use by the Star-MDC laboratory to evaluate its performance and usability. Methods: Agreement between the Siemens AD VIA Centaur Syphilis assay, Siemens IMMULITE (R) 2000 Syphilis Screen, and Biokit bioelisa Syphilis 3.0 assay was evaluated using 1251 patient samples (50 from known positives, 701 from patients referred for syphilis testing, and 500 from pregnant women). Reactive samples (i.e., reactive according to at least two of the three treponemal methods) were further evaluated using Western blot IgG and IgM, and Venereal Disease Research Laboratory (VDRL) testing. Results: Overall, positive and negative agreement was 100% between the Centaur and IMMULITE assays. In this study, overall agreement was 99.92% between either of the Siemens assays and the Biokit assay;positive agreement was 99%, and negative agreement was 100%. Overall, 0.88% (11/1251) of the samples were interpreted as positive/reactive based on the combined positive results by the AD VIA Centaur, IMMULITE 2000, and bioelisa assays;a positive Euroline anti-Treponema pallidum IgM blot;and a VDRL result of >= 1:8 In this study, no falsereactive samples were identified using this method. Conclusion: The Centaur Syphilis assay performance is comparable to the other 2 commercial assays. (C) 2014 The Authors. Published by Elsevier BM. This is an open access article under the CC BY license
Many surface finish methods are used to connect a substrate with the electric components of IT products in the micro-packaging process, and various types of lead-free solder have been developed as alternative material...
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Many surface finish methods are used to connect a substrate with the electric components of IT products in the micro-packaging process, and various types of lead-free solder have been developed as alternative materials to lead-based solder to reduce environmental contamination. However, there has been little research on the mechanical properties of the inter-metallic surface which is generated in the bumping process between the lead-free solder and surface films such as Ni/Au. The present work is to derive the material properties of a Ni/Au inter-metallic surface with SAC305 solder. A series of indentation tests were carried out by changing four nano-scale indentation depths and two strain rates. Also, a reverse algorithm method was adopted to determine the elastic-plastic stress-strain curve based on the load-displacement curve from the indentation test data. As a result of the material characterization effort, the mean elastic modulus, yield strength and strain hardening exponent of IMC with Ni/Au finish were determined.
Springback is one of the most important factors that affect the forming quality of tube *** this paper,the numerical simulation method was adopted to research on space shape of multi-bends metal tubes after *** on the...
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Springback is one of the most important factors that affect the forming quality of tube *** this paper,the numerical simulation method was adopted to research on space shape of multi-bends metal tubes after *** on the processing requirements,the springback and elongation of each bend was predicted through finite element *** the shape information of the metal tube after springback was restored by reverse algorithm,the space shape and position coordinates pre and post the springback were obtained through coordinate transformation,and the space shape information of the tube was gained by calculating the tube’s space offset after *** to experiments,the method was proved to be effective in predicting the space shape of the metal tube,which provides a new method to improve the bending precision and assembly precision of tube bending.
Frictional normal contact probing methods involving instrumented, depth-sensing indentation can be used to estimate the mechanical properties of small-volume structures and materials such as thin films and components ...
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Frictional normal contact probing methods involving instrumented, depth-sensing indentation can be used to estimate the mechanical properties of small-volume structures and materials such as thin films and components of micro-electro-mechanical systems. This paper describes a new method for estimating the plastic properties, i.e. the yield strength and strain hardening exponent, of ductile materials from the topography of scratches formed by a conical tip during an instrumented, depth-sensing frictional sliding test. The proposed reverse analysis (or inverse analysis) uses dimensionless functions derived from computational simulations to extract plastic properties from an instrumented scratch response performed on a standard, commercially available instrument. Sensitivity analysis indicates that an experimental error of 5% in the scratch hardness or the pile-up height induces an error of <22% in the estimated strain hardening exponent. Laboratory experiments illustrate how two aluminum alloy tempers of the same indentation hardness have significantly different pile-up as a result of different strain hardening. Comparative results between the frictional sliding test and traditional ten;de tests showed reasonable agreement for a total of II metallic alloys evaluated. These results confirm the potential usefulness of the proposed method as an engineering tool to probe plastic properties of small-volume materials and confined structures where it is difficult to obtain reliable estimates of mechanical properties by other means. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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