High-temperature thermal storage systems for advanced solar receivers materials selections

Advanced space power systems that use solar energy and Brayton or Stirling heat engines require thermal energy storage (TES) systems to operate continuously through periods of shade. The receiver storage units, key elements in both Brayton and Stirling systems, are designed to use the latent heat of fusion of phase-change materials (PCMs). The power systems under current consideration for near-future National Aeronautics and Space Administration space missions require working fluid temperatures in the 1100 to 1400 K range. The PCMs under current investigation that gave liquid temperatures within this range are the fluoride family of salts. However, these salts have low thermal conductivity, which causes large temperature gradients in the storage systems. Improvements can be obtained, however, with the use of thermal conductivity enhancements or metallic PCMs. In fact, if suitable containment materials can be found, the use of metallic PCMs would virtually eliminate the orbit associated temperature variations in TES systems. The high thermal conductivity and generally low volume change on melting of germanium and alloys based on silicon make them attractive for storage of thermal energy in space power systems. An approach to solving the containment problem, involving both chemical and physical compatibility, preparation of NiSi/NiSi2, and initial results for containment of germanium and NiSi/NiSi2, are presented

Development of surface treatments and alloy modifications for corrosion-resistant oxide scales

Alloys based on the long-range ordered system Fe{sub 3}Al are under development at Oak Ridge National Laboratory in support of coal conversion and combustion materials requirements. Of particular interest is the performance of these alloys in coal gasifiers involving product gases with relatively low oxygen activities and high sulfur activities. Using H{sub 2}S-H{sub 2}-H{sub 2}O gas mixtures, several experimental iron-aluminum alloys have been tested to assess the effects of aluminum concentration on oxidation-sulfidation response at 700 to 800{degree}C in a simulated gasifier environment. Metallographic and chemical analyses of the corrosion product scales and the underlying alloy were performed to determine the role of respective metallic elements on the sulfidation-oxidation processes. These results, together with thermogravimetric analyses, are discussed in terms of the apparent corrosion mechanisms and optimization of alloy composition for exposure to coal-derived environments. More recently, the corrosion performance of an Fe-28% Al-2% Cr alloy has been evaluated in gases produced by an operating gasifier. The reaction products and scale morphologies under actual service conditions were generally similar to the laboratory test results except for the presence of an ash deposit on the gasifier specimens. 2 refs., 7 figs., 4 tabs

AN EVALUATION OF ELECTRO-MACHINING FOR THE ANALYSIS OF METAL SURFACES

A procedure is described for the uniform removal of very thin sections of metal surfaces by electrolysis. Equipment requirements and the various parameters affecting operation are considered, and the results of applying the technique to studies of solid-state diffusion are discussed. The technique appears to offer considerable promise for evaluating chemical changes at metal surfaces which have taken place as a result of corrosion or diffusion processes. (auth

Alkali- Metal Corrosion of Refractory Metals

This report talks about the Alkali- Metal Corrosion of Refractory Metal

Corrosion of Fe-Cr-Mn alloys in thermally convective lithium

A series of austenitic Fe-Cr-Mn steels was exposed to circulating lithium at temperatures up to 500/sup 0/C. Two groups of the alloys, which contained 12 to 30 wt % Mn and 2 to 20 wt % Cr, were sequentially exposed for periods greater than 3000 h in a type 316 stainless steel thermal convection loop. Mass transfer of manganese caused very large weight losses from the steels containing 30 wt % Mn. However, the actual magnitude of corrosion losses for alloys containing 12 to 20 wt % Mn was difficult to establish due to competing surface reactions involving chromium

Barriers and facilitators experienced by osteopaths in implementing a biopsychosocial (BPS) framework of care when managing people with musculoskeletal pain – a mixed methods systematic review

BACKGROUND: Clinical practice guidelines commonly recommend adopting a biopsychosocial (BPS) framework by practitioners managing musculoskeletal pain. However, it remains unclear how osteopaths implement a BPS framework in the management of musculoskeletal pain. Hence, the objective of this review was to systematically appraise the literature on the current practices, barriers and facilitators experienced by osteopaths in implementing a BPS framework of care when managing people with musculoskeletal pain. METHODS: The following electronic databases from January 2005 to August 2020 were searched: PubMed, CINAHL, Science Direct, Google Scholar, ProQuest Central and SCOPUS. Two independent reviewers reviewed the articles retrieved from the databases to assess for eligibility. Any studies (quantitative, qualitative and mixed methods) that investigated the use or application of the BPS approach in osteopathic practice were included in the review. The critical appraisal skills program (CASP) checklist was used to appraise the qualitative studies and the Mixed Methods Appraisal Tool (MMAT) was used to appraise quantitative or mixed methods studies. Advanced convergent meta-integration was used to synthesise data from quantitative, qualitative and mixed methods studies. RESULTS: A total of 6 studies (two quantitative, three qualitative and one mixed methods) were included in the final review. While two key concepts (current practice and embracing a BPS approach) were generated using advanced meta-integration synthesis, two concepts (barriers and enablers) were informed from qualitative only data. DISCUSSION: Our review finding showed that current osteopathic practice occurs within in the biomedical model of care. Although, osteopaths are aware of the theoretical underpinnings of the BPS model and identified the need to embrace it, various barriers exist that may prevent osteopaths from implementing the BPS model in clinical practice. Ongoing education and/or workshops may be necessary to enable osteopaths to implement a BPS approach

MINIMIZING THE ADVERSE EFFECTS OF WORK ENVIRONMENT IN UPPER LIMB: A LITERATURE REVIEW

Introduction: Occupational problems are highly prevalent and act as impediments to effective labor. As per the statistics by WHO, in the year 2003, it was seen that back injuries shared the highest proportion in occupational disorders (60%), followed by neck and upper limb. Body: In the upper limb, any joint, be it the shoulder, elbow, wrist or hand, can be affected. Variable structures ranging from the tendon, ligament, nerve or muscle can be involved leading to problems effectuating in the form of pain, tenderness, swelling, and functional deficits. Common problems seen are carpal tunnel syndrome, muscle sprain-strain, and osteoarthritis in joints, etc. Management: ULMSDS can be prevented by incorporating activity in daily life awhile also keeping a check on posture. At workplace, architectural adjustments and changes in physical and social environment can help prevention exacerbation of upper limb conditions. Regular rest intervals can also be included to avoid prolonged fixation of joints in one position. Conclusion: This paper focuses on ULMSDS in an attempt to improve the quality of life through various intervention strategies within the work organization thus enhancing work quality and output of the companies. Article visualizations

Carburizing Baja Karbon Rendah Arang Kayu Sengon Dengan Proses Pendinginan Menggunakan Air Dan Oli Dengan Viskositas 10w - 40

The purpose of this research is carburizing low carbon steel, sengon wood charcoal by cooling process using water and oil with a viscosity of 10W- 40. In this study, a study of Bengkirai wood charcoal particles produced from incomplete combustion and using the collision method with the shaker mills model was carried out. Carburizing by cooling using water and oil with micro test, hardness and tensile to find out how much influence on material changes, to determine the hardness of the material, to determinethe mechanical properties. The results of the microstructure test, pack carburizing with cooling using SAE 10W-40 oil has a large number of pearlite crystals from ferrite crystals. The result of pack carburizing hardness test by cooling using water has the highest value with an average value of 471.8 VHN. Tensile test results of pack carburizing by cooling using water have the highest tensile strength with an average value of 632.27 MP