Reactive Joining of Thermally and Mechanically Sensitive Materials

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Bastian Rheingans ◽  
Roman Furrer ◽  
Jürg Neuenschwander ◽  
Irina Spies ◽  
Axel Schumacher ◽  
...  
Keyword(s):  
Borosilicate Glass ◽  
Microelectromechanical Systems ◽  
Emerging Technology ◽  
Testing Methods ◽  
Destructive Testing ◽  
Sensitive Material ◽  
Exothermal Reaction ◽  
Precise Control ◽  
Testing Procedures ◽  
Joining Process

Reactive joining, i.e., utilization of an exothermal reaction to locally generate the heat required for soldering or brazing, represents an emerging technology for flexible and benign joining of heat-sensitive materials, e.g., for microelectromechanical systems (MEMS) applications. However, for successful reactive joining, precise control of heat production and heat distribution is mandatory in order to avoid damaging of the components during the process. For the exemplary case of borosilicate glass, the reactive joining process for a both thermally and mechanically sensitive material is developed. Employing various nondestructive and destructive testing methods, typical problems which can occur upon reactive joining are identified, e.g., exposure of the joining zone to excessive temperatures, experience of thermal shock by the substrate due to sudden temperature increase, and generation of residual stresses in substrate and soldering zone. Utilizing the results of nondestructive and destructive testing, procedures for successful reactive joining of borosilicate glass, silicon and aluminum oxide are provided.

Implementation of Non-Destructive Impact Hammer Testing Methods in Determination of Brick Strength

2012 ◽  
Vol 174-177 ◽  
pp. 280-285 ◽  
Author(s):  
Jiří Brožovský
Keyword(s):  
Close Correlation ◽  
Non Destructive Testing ◽  
Testing Methods ◽  
Destructive Testing ◽  
Technical Standards ◽  
Testing Procedures ◽  
Rebound Number ◽  
Testing Field ◽  
Non Destructive

In the building industry, non-destructive testing methods are mostly used to determine parameters of concrete structures and concrete of its own; as to other materials, these methods serve semi-occasionally and, as a rule, testing procedures and evaluation are not codified in technical standards. One of non-destructive testing field of applications is testing of piece bricks. This paper deals with findings concerning non-destructive testing of clay solid bricks, honeycomb bricks and lime sand bricks by means of Schmidt Impact Hammers types LB/L. Described here are testing method, procedures of test finding evaluation as well as calibration correlations between impact hammer rebound number and compression strength or flexural strength (lime sand bricks only). Evaluated calibration correlations between impact hammer rebound number and brick strength feature close correlation; its coefficient varies between 0.95 and 0.98, therefore these values are usable in practice. When testing honeycomb bricks varying in hole arrangement and wall thickness, it is necessary to take both these factors into account through specification of calibration correlation of non-destructive/destructive tests of limited number of bricks.

Estimation of Thickness of Concrete Slab Members Using Impact Echo Method

2014 ◽  
Vol 605 ◽  
pp. 139-142
Author(s):  
Seong Uk Hong ◽  
Yong Taeg Lee ◽  
Seung Hun Kim ◽  
J.H. Na
Keyword(s):  
Concrete Slab ◽  
Hardness Test ◽  
Pulse Velocity ◽  
Non Destructive Testing ◽  
Testing Methods ◽  
Destructive Testing ◽  
Impact Echo ◽  
Maintenance And Repair ◽  
Non Destructive ◽  
Impact Echo Method

Recently, the interest in maintenance and repair of existing concrete structures have increased, and it is typical to use non-destructive testing methods such as rebound hardness test or ultrasonic pulse velocity method to execute maintenance and repair of structures efficiently. Many non-destructive testing methods are being used in practice such as at construction sites, but verification for site applications are quite inadequate. Thus, this study intends to evaluate the applicability of Impact Echo Method which is one of the non-destructive testing methods using stress wave. Total of four specimens were planned and produced. The thickness of concrete slab members was estimated using I.E(OLSENs Freedom Data PC with Win.TFS Software Version 2.5.2). The estimated materials of concrete members by IE was found to be IE-1 specimen 178mm, IE-2 specimen 197mm, IE-3 specimen 191mm, and IE-4 specimen 263mm, and the error rate was found to be 4.22%~18.67% (average 9.6%), showing that they are relatively well in agreement. In this study, the experiments were executed with the objective of estimating the thickness of concrete slab members using Impact Echo Method. Through this study, the applicability of thickness estimation in concrete slab members using impact echo method could be confirmed.

scholarly journals Seed viability of common ragweed (Ambrosia artemisiifolia L.) is affected by seed origin and age, but also by testing method and laboratory

NeoBiota ◽  
2021 ◽  
Vol 70 ◽  
pp. 193-221
Author(s):  
Rea Maria Hall ◽  
Bernhard Urban ◽  
Hana Skalova ◽  
Lenka Moravcová ◽  
Ulrike Sölter ◽  
...  
Keyword(s):  
Seed Viability ◽  
Ambrosia Artemisiifolia ◽  
Testing Methods ◽  
Triphenyltetrazolium Chloride ◽  
Viability Test ◽  
Common Ragweed ◽  
Testing Procedures ◽  
Testing Method ◽  
Seed Origin ◽  
Set Up

Common ragweed (Ambrosia artemisiifolia L.) is an annual Asteraceae species native to North America which is highly invasive across Europe and has harmful impacts, especially on human health and agriculture. Besides its wide ecological range, particularly its high reproductive power by seeds is promoting its spread to various habitats and regions. To prevent further spread and to control the plant, the European Commission funded projects and COST-Actions involving scientists from all over Europe. A joint trial was set up comprising eight different laboratories from Europe to study seed viability variation in different seed samples. Three different testing methods (viability test with 2,3,5-triphenyltetrazolium chloride (TTC), a germination test combined with a subsequent TTC test and a crush test) were tested within the EU-COST-Action SMARTER network to four different seed origins. The viability test results from different laboratories were compared for variation amongst tests and laboratories. The main aim was to optimise the reliability of testing procedures, but results revealed not only significant effects of seed origin and seed age on seed viability, but also considerable differences between the output of the individual testing methods and furthermore between laboratories. Due to these significant differences in the results of the testing labs, additionally a second test was set up. Twelve Austrian ragweed populations were used for TTC testing to obtain a precise adjustment of the testing method as well as a tight guideline for interpreting the results, particularly for the TTC state “intermediate” since a proper classification of TTC-intermediate coloured seeds is still a challenge when determining viability rates.

A Data Driven Policy to Minimize the Tuberculosis Testing Cost Among Healthcare Workers

2020 ◽  
Author(s):  
Vishnunarayan Girishan Prabhu ◽  
Kevin Taaffe ◽  
Ronald Pirrallo ◽  
Dotan Shvorin
Keyword(s):  
Skin Test ◽  
Direct Cost ◽  
Direct Costs ◽  
Switching Point ◽  
Interferon Gamma Release Assay ◽  
Total System ◽  
Testing Methods ◽  
Testing Procedures ◽  
Compliance Testing ◽  
Value Loss

Abstract Background The Centers for Disease Control and Prevention mandates that healthcare employees at high risk exposure to Tuberculosis (TB) undergo annual testing. Currently in the US, two methods of TB testing are commonly used: a two-step skin test or a whole-blood test. Each testing method has unique costs and considerations. Healthcare leadership’s test selection must not only account for direct cost such as material, procedure and resources, but also indirect costs such as employee workplace absence. Our purpose was to build a mathematical model to investigate the value loss perspective of these testing methods and assist leadership in their decision-making. Methods This model is based on an Upstate South Carolina healthcare employer’s costs affecting over 18,000 employees on 6 campuses. A process flow map identified the variations in TB testing methods that incorporated the varied material and procedural costs based on the Mantoux two-step tuberculin skin test (TST) and the Interferon-Gamma Release Assay test (IGRA). In addition to these direct costs, the subject’s time requirements involved with each test for 4 employee types and 6 travel-to-testing-site times were calculated. Results Regardless of direct cost variations, a switching point between testing procedures that minimized total system costs was most influenced by employee salary. In this model, an employee who is paid more than $48/hour should undergo IGRA blood testing irrespective of the travel time. As employee pay rate decreases to $30/hour, TST testing becomes more economical. Assuming an equal number of at-risk employees in each wage and travel category, switching from the current policy of 95% TST testing to integrated TST/IGRA testing would reduce TB compliance cost by 28%. Conclusions Mathematical modeling can assist healthcare system decision-makers in understanding the implications of employee TB compliance testing. This model distills the known direct costs of TST compared to IGRA testing and value loss perspectives of employee time into a definable switching point. Although actual costs and potential dollars saved depends on TB testing compliance rules and regulation, it appears that a mixed model of TB testing may be the most cost-effective approach for a large health care employer with multiple campuses.

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