14,595 research outputs found
Silver-chlorine fuel cell: A concept
Fuel cell regenerated by photochemical reduction enables novel slurry system to transport particles of reduced silver between regenerator section and anode. Fundamental reactions which provide electrical power from the fuel cell are given
Effect of refining variables on the properties and composition of JP-5
Potential future problem areas that could arise from changes in the composition, properties, and potential availability of JP-5 produced in the near future are identified. Potential fuel problems concerning thermal stability, lubricity, low temperature flow, combustion, and the effect of the use of specific additives on fuel properties and performance are discussed. An assessment of available crudes and refinery capabilities is given
Investigation of heatless desorption technology for carbon dioxide control in manned spacecraft
Heatless desorption technology for carbon dioxide control in manned spacecraf
Shock Diffraction by Convex Cornered Wedges for the Nonlinear Wave System
We are concerned with rigorous mathematical analysis of shock diffraction by
two-dimensional convex cornered wedges in compressible fluid flow governed by
the nonlinear wave system. This shock diffraction problem can be formulated as
a boundary value problem for second-order nonlinear partial differential
equations of mixed elliptic-hyperbolic type in an unbounded domain. It can be
further reformulated as a free boundary problem for nonlinear degenerate
elliptic equations of second order. We establish a first global theory of
existence and regularity for this shock diffraction problem. In particular, we
establish that the optimal regularity for the solution is across the
degenerate sonic boundary. To achieve this, we develop several mathematical
ideas and techniques, which are also useful for other related problems
involving similar analytical difficulties.Comment: 50 pages;7 figure
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The evolving maintenance of certification process: update on the financial status of the medical boards
Medical board organizations have accumulated large asset balances, in part due to the monetization of physician board recertification, as well as capital gains in positive investment conditions. Physicians across the country have raised concerns regarding the effectiveness and efficiency of existing recertification processes, to which the American Board of Medical Specialties and independent accreditation boards have responded with newly instituted changes. The present article analyzes the publicly available F990 tax forms of the medical boards in an effort to provide data to the ongoing debate. Although some boards have begun to mobilize assets in recent years, many continue to accumulate wealth. It remains to be seen whether the new recertification programs will bring about change or perpetuate organizational wealth
Valid Asymptotic Expansions for the Maximum Likelihood Estimator of the Parameter of a Stationary, Gaussian, Strongly Dependent Process
We establish the validity of an Edgeworth expansion to the distribution of the maximum likelihood estimator of the parameter of a stationary, Gaussian, strongly dependent process. The result covers ARFIMA type models, including fractional Gaussian noise. The method of proof consists of three main ingredients: (i) verification of a suitably modified version of Durbin's (1980) general conditions for the validity of the Edgeworth expansion to the joint density of the log-likelihood derivatives; (ii) appeal to a simple result of Skovgaard (1986) to obtain from this an Edgeworth expansion for the joint distribution of the log-likelihood derivatives; (iii) appeal to and extension of arguments of Bhattacharya and Ghosh (1978) to accomplish the passage from the result on the log-likelihood derivatives to the result for the maximum likelihood estimators. We develop and make extensive use of a uniform version of Dahlhaus's (1989) Theorem 5.1 on products of Toeplitz matrices; the extension of Dahlhaus's result is of interest in its own right. A small numerical study of the efficacy of the Edgeworth expansion is presented for the case of fractional Gaussian noise.Edgeworth expansions, long memory processes, ARFIMA models
The ASL-CDI 2.0: an updated, normed adaptation of the MacArthur Bates Communicative Development Inventory for American Sign Language
Vocabulary is a critical early marker of language development. The MacArthur Bates Communicative Development Inventory has been adapted to dozens of languages, and provides a bird’s-eye view of children’s early vocabularies which can be informative for both research and clinical purposes. We present an update to the American Sign Language Communicative Development Inventory (the ASL-CDI 2.0, https://www.aslcdi.org), a normed assessment of early ASL vocabulary that can be widely administered online by individuals with no formal training in sign language linguistics. The ASL-CDI 2.0 includes receptive and expressive vocabulary, and a Gestures and Phrases section; it also introduces an online interface that presents ASL signs as videos. We validated the ASL-CDI 2.0 with expressive and receptive in-person tasks administered to a subset of participants. The norming sample presented here consists of 120 deaf children (ages 9 to 73 months) with deaf parents. We present an analysis of the measurement properties of the ASL-CDI 2.0. Vocabulary increases with age, as expected. We see an early noun bias that shifts with age, and a lag between receptive and expressive vocabulary. We present these findings with indications for how the ASL-CDI 2.0 may be used in a range of clinical and research settingsAccepted manuscrip
Feasibility study of high performance hydrogen-oxygen fuel cells Final technical report
Engineering analysis for evaluating moving bed and mediator hydrogen-oxygen fuel cell conceptual design
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