2,031 research outputs found
Impact of microphysics on the growth of one-dimensional breath figures
Droplet patterns condensing on solid substrates (breath figures) tend to
evolve into a self-similar regime, characterized by a bimodal droplet size
distribution. The distributions comprise a bell-shaped peak of monodisperse
large droplets, and a broad range of smaller droplets. The size distribution of
the latter follows a scaling law characterized by a non-trivial polydispersity
exponent. We present here a numerical model for three-dimensional droplets on a
one-dimensional substrate (fiber) that accounts for droplet nucleation, growth
and merging. The polydispersity exponent retrieved using this model is not
universal. Rather it depends on the thickness of the fiber and on details of
the droplet interaction leading to merging. In addition, its values
consistently differ from the theoretical prediction by Blackman (Phys. Rev.
Lett., 2000). Possible causes of this discrepancy are pointed out
DORMAN computer program (study 2.5). Volume 1: Executive summary
The DORCA Applications study has been directed at development of a data bank management computer program identified as DORMAN. Because of the size of the DORCA data files and the manipulations required on that data to support analyses with the DORCA program, automated data techniques to replace time-consuming manual input generation are required. The Dynamic Operations Requirements and Cost Analysis (DORCA) program was developed for use by NASA in planning future space programs. Both programs are designed for implementation on the UNIVAC 1108 computing system. The purpose of this Executive Summary Report is to define for the NASA management the basic functions of the DORMAN program and its capabilities
Acoustic cavitation and sonochemistry
Sonochemistry is the use of cavitation for achieving a chemical conversion. When microbubbles are driven in the nonlinear regime, localized extreme temperatures (up to 10000 K) and pressures (up to 1000 bar) can be reached upon collapse, the surrounding liquid remaining ambient,thus giving origin to intriguing phenomena, such as light emission (sonoluminescence) and high temperature chemical reactions (sonochemistry). These reaction products then diffuse outside the bubble and dissolve inside the surrounding liquid. Due to their unstable nature, they are highly reactice and have therefore a vast potential for technological applications, eg. chemical synthesis, water cleaning, cells disruption and textile processing. However, sonochemical reactors are known to suffer from a lack of efficiency and controllability, which has until now prevented the large-scale employment of this technology. When we started the present study the challenge was to improve the efficiency of a sonochemical reactor, by reducing its dimensions to a micrometric scale, still retaining the possibility to control the precess
Programmatic effects of utilizing various space tug options
The results are summarized of the computerized (DORCA) analyses of a number of NASA/Non-NASA and DoD payload mission models that have been used in conjunction with studies of the Space Transportation System (STS). The first analysis performed was on the 1971 NASA/Non-NASA and DoD mission models. Subsequent to that, analyses of the June 1972 excursion to the 1971 NASA/Non-NASA mission models were performed. The mission models have two basic versions; i.e., one employing expendable payloads and another employing a best mix of expendable and reusable payloads. Both versions of the models have the same payload deployment schedule. However, in the best mix version, payloads are retrieved from orbit and whenever possible, refurbished payloads are deployed. The analyses were performed to determine the relative merits to different Tug configurations and of Tug combinations employed in several phased development schemes
Manned systems utilization analysis (study 2.1). Volume 3: LOVES computer simulations, results, and analyses
The LOVES computer program was employed to analyze the geosynchronous portion of the NASA's 1973 automated satellite mission model from 1980 to 1990. The objectives of the analyses were: (1) to demonstrate the capability of the LOVES code to provide the depth and accuracy of data required to support the analyses; and (2) to tradeoff the concept of space servicing automated satellites composed of replaceable modules against the concept of replacing expendable satellites upon failure. The computer code proved to be an invaluable tool in analyzing the logistic requirements of the various test cases required in the tradeoff. It is indicated that the concept of space servicing offers the potential for substantial savings in the cost of operating automated satellite systems
DORMAN computer program (study 2.5). Volume 3: Original data bank listing
A number of analyses have been performed using the DORCA program for several NASA-funded Aerospace Corporation studies in the past few years. The data decks containing the input data for these analyses have been compiled and are submitted, under separate cover. A few of the data decks are full (basic) decks containing every data item and are used as reference decks in the data bank. The other data decks were obtained by differencing a full deck with respect to one of the reference decks. Using the DORMAN program, a full deck can be recreated from the modified deck and its reference deck when and if desired. The content and structure of the data bank are described. A description of each of these data decks is presented. Three of the cases that are included in this volume have become so widely recognized and accepted that additional descriptive material has been provided. The three cases are: Case 500 Costs, Case 506 Costs, and Case 403
The future of insurance intermediation in the age of the digital platform economy
Today most insurance is sold by over a million brokers and independent agents acting as intermediaries between the insurance companies and their customers. Digitalization and changing customer behavior have fostered the development of insurtech businesses, and, more recently, multi-sided platforms are emerging as new market forms for insurance intermediation. This paper aims to provide a better understanding of how the emergence of the platform economy with a market dominated by multi-sided platforms potentially impacts insurance intermediation in the future. Using inductive content analysis on the results of a systematic literature review of the body of research on insurance intermediation, we identify the key functional roles fulfilled by insurance intermediaries. Applying these roles to a literature review on multi-sided platforms allows us to compare how different market forms and players embody the functional roles of intermediaries. Our findings suggest that multi-sided platforms are better able to perform certain roles in terms of agility, scale and scope, and we discuss the future role of platforms in insurance intermediation
Pion-nucleus optical potential valid up to the DELTA-resonance region
We present in this article an optical potential for the -nucleus
interaction that can be used in various studies involving -nucleus
channels. Based on earlier treatments of the low energy -nucleus optical
potential, we have derived a potential expression applicable from threshold up
to the -resonance region. We extracted the impulse approximation form
for this potential from the scattering amplitude and then added to it
kinematical and physical corrections. The kinematic corrections arise from
transforming the impulse approximation expression from the center of
mass frame to the -nucleus center of mass frame, while the physical
corrections arise mostly from the many-body nature of the -nucleus
interaction. By taking advantage of the experimental progress in our knowledge
of the process, we have updated earlier treatments with parameters
calculated from state-of-the-art experimental measurements.Comment: 23 pages, 12 figures. Accepted for publication in Physical Review
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