2,906 research outputs found

    Monolithic Solid Oxide Fuel Cell development

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    The Monolithic Solid Oxide Fuel Cell (MSOFC) is an oxide-ceramic structure in which appropriate electronic and ionic conductors are fabricated in a honeycomb shape similar to a block of corrugated paperboard. These electronic and ionic conductors are arranged to provide short conduction paths to minimize resistive losses. The power density achievable with the MSOFC is expected to be about 8 kW/kg or 4 kW/L, at fuel efficienceis over 50 percent, because of small cell size and low resistive losses in the materials. The MSOFC operates in the range of 700 to 1000 C, at which temperatures rapid reform of hydrocarbon fuels is expected within the nickel-YSZ fuel channels. Tape casting and hot roll calendering are used to fabricate the MSOFC structure. The performance of the MSOFC has improved significantly during the course of development. The limitation of this system, based on materials resistance alone without interfacial resistances, is 0.093 ohm-sq cm area-specific resistance (ASR). The current typical performance of MSOFC single cells is characterized by ASRs of about 0.4 to 0.5 ohm-sq cm. With further development the ASR is expected to be reduced below 0.2 ohm-sq cm, which will result in power levels greater than 1.4 W/sq cm. The feasibility of the MSOFC concept was proven, and the performance was dramatically improved. The differences in thermal expansion coefficients and firing shrinkages among the fuel cell materials were minimized. As a result of good matching of these properties, the MSOFC structure was successfully fabricated with few defects, and the system shows excellent promise for development into a practical power source

    The effect of total knee arthroplasty on joint movement during functional activities and joint range of motion with particular regard to higher flexion users

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    Study aimed to evaluate active and functional knee excursion of patients before and after total knee arthroplasty (TKA) and to determine whether TKA restores quality of life related to functional activities of daily living. Found that although TKA offers excellent pain relief and contributes to the overall well-being of the patient, these results suggest that it also leads to a reduced range of active and functional motion in the majority of patients. This is associated with a lower-than-normal physical quality of life. The design of implants and rehabilitation programmes should be reconsidered so that better range of motion and quality of life can be achieved for patients

    Summer Camp as a Force for 21st Century Learning: Exploring Divergent Thinking and Activity Selection in a Residential Camp Setting

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    This study investigated change in divergent thinking (DT), an indicator of creative potential, at two gender-specific residential summer camps. Additionally, this study examined whether the change in DT varied by gender and by the type of activities campers self-select. Quantitative methods, using a quasi-experimental design was used in order to understand differences in camper scores. A total of 189 youth, 100 girls, 89 boys, between the ages of 9 and 14 years participated in the current study. Participants were administered a modified version of Guilford\u27s (1967) alternate uses task, a measure of DT, in which respondents were asked questions such as name all of the uses for a brick or name all of the uses for a plate before the camp session started, and then again at the end of the two-week session. Results indicate overall mean significant increases in DT across all scoring methods of fluency, flexibility, and originality. Participants who self-selected one or more artistic activities (e.g., drama, arts and crafts, dance) had significant increases on the tasks as opposed to participants who did not select any artistic activities (e.g., basketball, baseball, archery). Finally, girls significantly increased across all scoring methods, whereas boys slightly increased in fluency and flexibility but not in originality. These results indicate residential summer camp may provide a creativity benefit for youth in attendance, especially those who participate in certain activities. Practitioners should use this study to understand their own programming in terms of creativity, activity offerings, and camp cultur

    Self-employment income gap in Great Britain: How much and who?

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    This is the author accepted manuscript. The final version is available from Oxford University Press via the DOI in this record.This paper utilises an expenditure survey-based data set that is rich in terms of observable characteristics to estimate the ‘income gap’ (defined to be one minus the proportion of reported to true income) of the self-employed in Great Britain. It also estimates the evasion response of the individual characteristics of the self-employed. It emerges that self-employed report, on average, around 80.4 percent of their income to the tax authority, which translates into an income-gap of 19.6 percent which varies significantly by sex, age, and region. In particular, male self-employed taxpayers underreport more than female ones, and they, in general, become more compliant as they age. Particular emphasis is paid to verifying that the income gap observed cannot be explained by other reasons than underreporting.This work was supported by the Economic and Social Research Council (ESRC) under grant no. ES/K005944/

    Electrochemical Solutions for Advanced Life Support

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    The Oxygen Generating Assembly (OGA) on-board the International Space Station (ISS) employs a polymer electrolyte membrane (PEM) water electrolysis cell stack to electrochemically dissociate water into its two components oxygen and hydrogen. Oxygen is provided to the cabin atmosphere for crew respiration while the hydrogen is delivered to a carbon dioxide reduction system to recover oxygen as water. The design of the OGA evolved over a number of years to arrive at the system solution that is currently operational on ISS. Future manned missions to space will require advanced technologies that eliminate the need for resupply from earth and feature in-situ resource utilization to sustain crew life and to provide useful materials to the crew. The architects planning such missions should consider all potential solutions at their disposal to arrive at an optimal vehicle solution that minimizes crew maintenance time, launch weight, installed volume and energy consumption demands. Skyre is developing new technologies through funding from NASA, the Department of Energy, and internal investment based on PEM technology that could become an integral part of these new vehicle solutions. At varying stages of Technology Readiness Level (TRL) are: an oxygen concentrator and compressor that can separate oxygen from an air stream and provide an enriched oxygen resource for crew medical use and space suit recharge without any moving parts in the pure oxygen stream; a regenerative carbon dioxide removal system featuring a PEM-based sorbent regenerator; a carbon dioxide reduction system that electrochemically produces organic compounds that could serve as fuels or as a useful intermediary to more beneficial compounds; and an electrochemical hydrogen separator and compressor for hydrogen recycle. The technical maturity of these projects is presented along with pertinent performance test data that could be beneficial in future study efforts

    Impact of the abolition of EU Milk quotas on Agriculture in the UK

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    In recent years the CAP has undergone significant reforms, but the dairy sector has largely avoided wholesale changes. The sector, however, is now faced with a significant effort by the Commission to instigate reform. In this study the FAPRI-UK modelling system is simulated to identify the impact of abolishing or phasing out EU milk quotas on the dairy sector in the UK and the results are compared against a 2007 Baseline projection (2007--2016). The results demonstrate that although the impact of the abolition of dairy quotas is fairly modest at the EU-25 level, significant impacts are apparent at the individual country level.Milk Quotas, CAP Reform, Commodity Modelling, Agricultural and Food Policy, International Relations/Trade, Livestock Production/Industries,

    β-adrenergic inhibition prevents action potential and calcium handling changes during regional myocardial ischemia

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    β-adrenergic receptor (β-AR) blockers may be administered during acute myocardial infarction (MI), as they reduce energy demand through negative chronotropic and inotropic effects and prevent ischemia-induced arrhythmogenesis. However, the direct effects of β-AR blockers on ventricular electrophysiology and intracellular Ca2+ handling during ischemia remain unknown. Using optical mapping of transmembrane potential (with RH237) and sarcoplasmic reticulum (SR) Ca2+ (with the low-affinity indicator Fluo-5N AM), the effects of 15 min of regional ischemia were assessed in isolated rabbit hearts (n = 19). The impact of β-AR inhibition on isolated hearts was assessed by pre-treatment with 100 nM propranolol (Prop) prior to ischemia (n = 7). To control for chronotropy and inotropy, hearts were continuously paced at 3.3 Hz and contraction was inhibited with 20 μM blebbistatin. Untreated ischemic hearts displayed prototypical shortening of action potential duration (APD80) in the ischemic zone (IZ) compared to the non-ischemic zone (NI) at 10 and 15 min ischemia, whereas APD shortening was prevented with Prop. Untreated ischemic hearts also displayed significant changes in SR Ca2+ handling in the IZ, including prolongation of SR Ca2+ reuptake and SR Ca2+ alternans, which were prevented with Prop pre-treatment. At 5 min ischemia, Prop pre-treated hearts also showed larger SR Ca2+ release amplitude in the IZ compared to untreated hearts. These results suggest that even when controlling for chronotropic and inotropic effects, β-AR inhibition has a favorable effect during acute regional ischemia via direct effects on APD and Ca2+ handling

    POSTURING SPARES FOR STRATEGIC POWER COMPETITION

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    As the distribution of power evolves across the world and creates new threats, the Department of Defense (DOD) must continually seek ways to maintain a competitive advantage among dimensions of power that enable us to advance our interests and values. America’s competitors are becoming more assertive and technologically sound, meaning the Navy must improve readiness and adopt innovative capabilities. In the face of strategic challenges, it is important that there is a shift from legacy platforms to novel weapon system readiness. The purpose of this research was to evaluate the survivability of a primary defense weapon system onboard Arleigh Burke Class guided-missile destroyers (DDGs), the Phalanx Close-in-Weapon-System (CIWS), under continuous operation in a contested environment based on current supply forecasting. Currently, forecast supply models do not consider the increased demand in contested environments or additive manufacturing solution-based delivery. To extend the defense operational availability (Ao) time of primary defense systems, a selection methodology was used to identify the weapon components with the highest failure rates. Through simulation-based modeling, these components were evaluated for additive manufacturing capabilities and potential production onboard. This thesis exposed a critical shortcoming of the supply capacity in a contested environment while offering potential solutions to increase the effectiveness of operational sustainment.NPS Naval Research ProgramThis project was funded in part by the NPS Naval Research Program.Lieutenant Commander, United States NavyLieutenant Commander, United States NavyLieutenant, United States NavyApproved for public release. Distribution is unlimited
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