440 research outputs found

    Fabrication and test of a space power boiler feed electromagnetic pump. Part 2: Test facility and performance test

    Get PDF
    A three-phase helical induction electromagnetic pump, designed for the boiler-feed pump of a potassium Rankine-cycle space power system, was built and tested. The pump was tested over a range of potassium temperatures from 900 to 1400 F, flow rates from 0.75 to 4.85 lb/sec, developed pressures up to 340 psi, net positive suction heads (NPSH) from 1 to 22 psi, and NaK coolant temperatures from 800 to 950 F. The maximum efficiency at the pump design point of 3.25 lb/sec flow rate, 240 psi developed pressure, 1000 F potassium inlet temperature, and 800 F NaK coolant temperature was 16.3 percent. The tests also showed successful operation of the pump at an NPSH as low as 1.5 psi without cavitating

    A Conceptual Design Study on the Application of Liquid Metal Heat Transfer Technology to the Solar Thermal Power Plant

    Get PDF
    Alkali metal heat transfer technology was used in the development of conceptual designs for the transport and storage of sensible and latent heat thermal energy in distributed concentrator, solar Stirling power conversion systems at a power level of 15 kWe per unit. Both liquid metal pumped loop and heat pipe thermal transport were considered; system configurations included: (1) an integrated, focal mounted sodium heat pipe solar receiver (HPSR) with latent heat thermal energy storage; (2) a liquid sodium pumped loop with the latent heat storage, Stirling engine-generator, pump and valves located on the back side of the concentrator; and (3) similar pumped loops serving several concentrators with more centralized power conversion and storage. The focus mounted HPSR was most efficient, lightest and lowest in estimated cost. Design confirmation testing indicated satisfactory performance at all angles of inclination of the primary heat pipes to be used in the solar receiver

    Fosforgödslingseffektivitet i långliggande bördighetsförsök

    Get PDF
    Rapid population growth and the fact that phosphorous is a limited resource implies that the question regarding an efficient use of phosphorus is of great importance, and consequently,that the phosphorous use efficiency should be as high as possible. The view on phosphorous use efficiency, and how this is calculated, has varied over time. This has had great implications on what type of research that has been conducted, which have resulted in an inconsistency between the academic’s view on the subject and recommendations received by farmers. The purpose of this paper is to calculate the phosphorus use efficiency in the Swedish long term fertility experiments. Calculations are made using different methods in order to evaluate which method is most suitable for calculating phosphorus use efficiency. Furthermore, the purpose is to determine at which P-AL you receive the highest efficiency for different soils and crops. Calculations made using the difference method consequently demonstrate lower phosphorus use efficiency than calculations made using the balance method. This implies that phosphorus is reversely fixed in the soil. The efficiency obtained using the difference method is strongly dependent on the yield in a references patch left unfertilized. Calculations on phosphorus use efficiency should therefore be made using the balance method. The highest efficiency achieved was 72 %, after correcting for an increase in P-AL. Nearly all of the sites had a phosphorus use efficiency over 25 %, which is commonly recognized as the upper limit. Yield in relation to P-AL differs greatly between different soils, differences that cannot be explained by simple soil parameters, such as content of clay and organic matter. According to Jodbruksverkets recommendations, replacement fertilizing should be done on soils graded as having phosphorus class III. The calculations show that the yield-effect of fertilizing decreases around P-AL 4, which corresponds to the lower regions of phosphorus class III. For some of the soils, this effect is observed at lower P-AL levels. There are significant differences between P-AL level required for a certain yield when different crops are compared. Calculations show that winter wheat is more tolerant to lower P-AL levels than spring barley and spring oilseeds. This is something that should be considered when planning phosphorus fertilization.Den ökande befolkningens efterfrågan på mat och bristen på fosfor gör att effektiviteten i fosforgödslingen bör vara så hög som möjligt. Synen på fosforgödslingseffektivitet, och hur denna bör beräknas har sett olika ut under olika tidsperioder. Detta har fått implikationer för vilken forskning som bedrivits vilket i sin tur har lett till en diskripans mellan forskarvärldens syn på fosforgödslingseffektivitet och de praktiska rekommendationerna till lantbrukare. Syftet med detta arbete är att beräkna fosforgödslingseffektiviteten i långliggande bördighetsförsök på 12 platser i Sverige. Beräkningarna är gjorda med olika metoder för att utröna vilken metod som är lämpligast. Syftet med arbetet är även att utröna vilket P-AL som är optimalt för högst fosforgödslingseffektivitet för olika jordar och grödor. Beräkningar för långliggande bördighetsförsök i Sverige visar att effektiviteten av fosforgödslingen beräknat med differensmetoden är konsekvent lägre än beräknat med balansmetoden. Detta betyder att fosfor fixeras reversibelt i marken. Effektivitetsberäkningar bör göras med balansmetoden eftersom den effektivitet som erhålles med differensmetoden är starkt beroende av vad som sker i en ruta där ingen gödsling sker. Den högsta effektivitet som uppnåddes med balansmetoden, efter korrigering för ökning i P-AL, är 72 %. I princip samtliga beräkningar låg över de 25 % som tidigare ansetts vara maximal effektivitet. När det gäller skördens förhållande till P-AL är skillnaderna mellan olika jordar stor, och inget mönster finns som enkelt kan förklaras med markparametrar. Enligt Jordbruksverkets rekommendationer bör enbart ersättningsgödsling ske vid klass III. För flera av jordarna gäller att skördekurvan planar ut runt P-AL 4 vilket motsvarar en låg klass III, men för flera av jordarna sker utplaningen tidigare. Kurvorna visar även stor variation inom intervallet för klass III som går från P-AL 4,1-8,0. Det finns tydliga skillnader mellan vilket P-AL som krävs för att nå en viss skörd av olika grödor. Beräkningarna visar att höstvete klarar ett lägre P-AL än vårkorn och våroljeväxter som är allra känsligas något som bör beaktas vid gödslingsplanering

    Possibilities to increase the phosphorus utilization rate in crops with the use of inorganic fertilizers

    Get PDF
    The objective of this thesis is to explore opportunities to enhance the phosphorus use efficiency of inorganic fertilizers in crop production, with techniques available today and in the future. Phosphorus is a finite resource of declining quality; therefore a phosphorus use efficiency in crop production of only 15-30 % is unacceptable. The main reason for low efficiency is the retention by Ca and Mg in calcareous soils and Fe and Al in non-calcareous soils. Due to the low mobility of phosphorus, plant uptake is mainly dependent on root growth rather than diffusion. Therefore, measurements need to be taken that benefit contact between root and fertilizer, before fertilizer phosphorus becomes unavailable to the plant. Among the most common fertilizers no consistent difference in efficiency exists although the initial reaction pH of the fertilizer may have an impact on the efficiency. Dressing should be done every year in spring and root uptake is enhanced by placing the fertilizer in bands under the seed, about 10 cm from the surface. It is possible to make complimentary dressing by foliar application. Further enhancements may be accomplished by using liquid fertilizer. Efficiency may be further improved on some soils by increasing the granular size to limit contact between fertilizer and soil, thereby minimizing retention and keeping phosphorus in solution. On other soils it might be of advantage to use a smaller granular size that places phosphorus fertilizers in a continuous band to improve root proliferation. Enhanced efficiency phosphorus fertilizers (EEF:s) may further increase plant utilization by slow release or cation adsorption. However, more research needs to be done on the subject. For maximum efficiency, fertilizer phosphorus in soil solution must be synchronized with plant demand. To feed a growing world population at a reasonable environmental as well as monetary expense, further steps need to be taken to increase the efficiency to an acceptable level

    A Conceptual Design Study of a High Temperature Solar Thermal Receiver

    Get PDF
    A conceptual design was made for a solar thermal receiver capable of operation in the 1095 to 1650 C (2000 to 3000 F) temperature range. This receiver is designed for use with a two-axis paraboloidal concentrator in the 25 to 150 kW sub t power range, and is intended for industrial process heat, Brayton engines, or chemical/fuels reactions. Three concepts were analyzed parametrically. One was selected for conceptual design. Its key feature is a helical coiled tube of sintered silicon nitride which serves as the heat exchanger between the incident solar radiation and the working fluid. A mechanical design of this concept was prepared, and both thermal and stress analysis performed. The analysis showed good performance, low potential cost in mass production, and adaptability to both Brayton cycle engines and chemical/fuels production

    Rio high for Johnathan: shooter qualifies for olympics after bagging 1Om air pistol gold

    Get PDF
    Background and objective Previous research suggests that measures of cognitive process may be confounded by the inclusion of items that also assess cognitive content. The primary aims of this content review were to: (1) identify the domains of cognitive processes assessed by measures used in pain research; and (2) determine if pain‐specific cognitive process measures with adequate psychometric properties exist. Databases and data treatment PsychInfo, CINAHL, PsycArticles, MEDLINE, and Academic Search Complete databases were searched to identify the measures of cognitive process used in pain research. Identified measures were double coded and the measure's items were rated as: (1) cognitive content; (2) cognitive process; (3) behavioural/social; and/or (4) emotional coping/responses to pain. Results A total of 319 scales were identified; of these, 29 were coded as providing an un‐confounded assessment of cognitive process, and 12 were pain‐specific. The cognitive process domains assessed in these measures are Absorption, Dissociation, Reappraisal, Distraction/Suppression, Acceptance, Rumination, Non‐Judgment, and Enhancement. Pain‐specific, un‐confounded measures were identified for: Dissociation, Reappraisal, Distraction/Suppression, and Acceptance. Psychometric properties of all 319 scales are reported in supplementary material. Conclusions To understand the importance of cognitive processes in influencing pain outcomes as well as explaining the efficacy of pain treatments, valid and pain‐specific cognitive process measures that are not confounded with non‐process domains (e.g., cognitive content) are needed. The findings of this content review suggest that future research focused on developing cognitive process measures is critical in order to advance our understanding of the mechanisms that underlie effective pain treatment. Significance Many cognitive process measures used in pain research contain a ‘mix’ of items that assess cognitive process, cognitive content, and behavioural/emotional responses. Databases searched: PsychInfo, CINAHL, PsycArticles, MEDLINE and Academic Search Complete. This review describes the domains assessed by measures assessing cognitive processes in pain research, as well as the strengths and limitations of these measures

    Wellness and Multiple Sclerosis: The National MS Society Establishes a Wellness Research Working Group and Research Priorities

    Get PDF
    Background: People with multiple sclerosis (MS) have identified “wellness” and associated behaviors as a high priority based on “social media listening” undertaken by the National MS Society (i.e. the Society). Objective: The Society recently convened a group that consisted of researchers with experience in MS and wellness-related research, Society staff members, and an individual with MS for developing recommendations regarding a wellness research agenda. Method: The members of the group engaged in focal reviews and discussions involving the state of science within three approaches for promoting wellness in MS, namely diet, exercise, and emotional wellness. Results: That process informed a group-mediated activity for developing and prioritizing research goals for wellness in MS. This served as a background for articulating the mission and objectives of the Society’s Wellness Research Working Group. Conclusion: The primary mission of the Wellness Research Working Group is the provision of scientific evidence supporting the application of lifestyle, behavioral, and psychosocial approaches for promoting optimal health of mind, body, and spirit (i.e. wellness) in people with MS as well as managing the disease and its consequences

    Biomethane Yield from Different European Phragmites australis Genotypes, Compared with Other Herbaceous Wetland Species Grown at Different Fertilization Regimes

    Get PDF
    Phragmites australis, Typha latifolia, T. angustifolia and Arundo donax are tall wetland graminoids with the potential to replace fossil fuels under sustainable cultivation conditions. We investigated the biomethane (CH4) production of these four species, including four different genotypes of P. australis, which represent the high intraspecific diversity of European reed. All plants were grown under three different macronutrient supplies (no nutrients added, an equivalent of 75 kg N ha−1 year−1 added and an equivalent of 500 kg N ha−1 year−1 added). Biomethane production was measured in four independent batch digestion tests. Across all experiments, fertilization regime had little effect on CH4 yield, which was on average 222 ± 31 L kg−1 volatile solids (VS). The lowest yield was produced by T. angustifolia (140 L kgVS−1) receiving no nutrients, while the highest yield was produced by A. donax (305 L kgVS−1) in the highest nutrient treatment. The intraspecific diversity of P. australis did not affect biomethane production. All P. australis genotypes produced on average 226 ± 19 L CH4 kgVS−1, which, although high, was still lower than conventional biogas species. The biomass production of P. australis was less increased by fertilization than that of Typha sp. and A. donax, but all species had similar biomass without fertilization

    Characterizing chronic pain phenotypes in multiple sclerosis : a nationwide survey study

    Get PDF
    Acknowledgements The National Multiple Sclerosis Society (NMSS) provided participant recruitment support by distributing study advertisements via their email listserv. The Michigan Institute for Clinical & Health Research (MICHR: NIH award number UL1TR002240) provided participant recruitment support through the UMHealthResearch.org website. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The authors thank Shubhangi Kulkarni, MS, for her contribution in coordinating this study and collecting these data. The authors have no conflicts of interest to report.Peer reviewedPostprin
    corecore