2,509 research outputs found
Modular Workflow Engine for Distributed Services using Lightweight Java Clients
In this article we introduce the concept and the first implementation of a
lightweight client-server-framework as middleware for distributed computing. On
the client side an installation without administrative rights or privileged
ports can turn any computer into a worker node. Only a Java runtime environment
and the JAR files comprising the workflow client are needed. To connect all
clients to the engine one open server port is sufficient. The engine submits
data to the clients and orchestrates their work by workflow descriptions from a
central database. Clients request new task descriptions periodically, thus the
system is robust against network failures. In the basic set-up, data up- and
downloads are handled via HTTP communication with the server. The performance
of the modular system could additionally be improved using dedicated file
servers or distributed network file systems.
We demonstrate the design features of the proposed engine in real-world
applications from mechanical engineering. We have used this system on a compute
cluster in design-of-experiment studies, parameter optimisations and robustness
validations of finite element structures.Comment: 14 pages, 8 figure
Half-Life of O
We have measured the half-life of O, a superallowed decay isotope. The O was produced by the
C(He,n)O reaction using a carbon aerogel target. A
low-energy ion beam of O was mass separated and implanted in a thin
beryllium foil. The beta particles were counted with plastic scintillator
detectors. We find s. This result is
higher than an average value from six earlier experiments, but agrees more
closely with the most recent previous measurement.Comment: 10 pages, 5 figure
Planetary/DOD entry technology flight experiments. Volume 3: Planetary entry flight experiments handbook
The environments produced by entry into Jupiter and Saturn atmospheres are summarized. Worst case design environments are identified and the effect of entry angle, type of atmosphere and ballistic coefficient variations are presented. The range of environments experienced during earth entry is parametrically described as a function of initial entry conditions. The sensitivity of these environments to vehicle ballistic coefficient and nose radius is also shown. An elliptical deorbit maneuver strategy is defined in terms of the velocity increment required versus initial entry conditions and apoapsis altitude. Mission time, ground track, and out of plane velocity penalties are also presented. Performance capabilities of typical shuttle launched boosters are described including the initial entry conditions attainable as a function of paylaod mass and apoapsis altitude
Planetary/DOD entry technology flight experiments. Volume 4: DOD entry flight experiments
For abstract, see vol. 1
Planetary/DOD entry technology flight experiments. Volume 1: Executive summary
The feasibility of using the space shuttle to launch planetary and DoD entry flight experiments was examined. The results of the program are presented in two parts: (1) simulating outer planet environments during an earth entry test, the prediction of Jovian and earth radiative heating dominated environments, mission strategy, booster performance and entry vehicle design, and (2) the DoD entry test needs for the 1980's, the use of the space shuttle to meet these DoD test needs, modifications of test procedures as pertaining to the space shuttle, modifications to the space shuttle to accommodate DoD test missions and the unique capabilities of the space shuttle. The major findings of this program are summarized
Nonlinear Dynamics of Capacitive Charging and Desalination by Porous Electrodes
The rapid and efficient exchange of ions between porous electrodes and
aqueous solutions is important in many applications, such as electrical energy
storage by super-capacitors, water desalination and purification by capacitive
deionization (or desalination), and capacitive extraction of renewable energy
from a salinity difference. Here, we present a unified mean-field theory for
capacitive charging and desalination by ideally polarizable porous electrodes
(without Faradaic reactions or specific adsorption of ions) in the limit of
thin double layers (compared to typical pore dimensions). We illustrate the
theory in the case of a dilute, symmetric, binary electrolyte using the
Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae
are available for salt adsorption and capacitive charging of the diffuse part
of the double layer. We solve the full GCS mean-field theory numerically for
realistic parameters in capacitive deionization, and we derive reduced models
for two limiting regimes with different time scales: (i) In the
"super-capacitor regime" of small voltages and/or early times where the porous
electrode acts like a transmission line, governed by a linear diffusion
equation for the electrostatic potential, scaled to the RC time of a single
pore. (ii) In the "desalination regime" of large voltages and long times, the
porous electrode slowly adsorbs neutral salt, governed by coupled, nonlinear
diffusion equations for the pore-averaged potential and salt concentration
Comparison of monophasic with single and dual capacitor biphasic waveforms for nonthoracotomy canine internal defibrillation
AbstractMonophasic and single capacitor and dual capacitor biphasic truncated exponential shocks were tested in pentobarbital-anesthetized dogs with use of a nonthoracotomy internal defibrillation pathway consisting of a right ventricular catheter electrode and a subcutaneous chest wall patch electrode. Seven dogs weighing 20.2 ± 0.5 kg were utilized. Monophasic pulses of 10 ms duration were compared with three biphasic pulses. All biphasic waveforms had an initial positive phase (PI) followed by a terminal negative phase (P2) and the total duration of Pt Plus P2 was 10 ms. The dual capacitor biphasic waveform (PI 9 ms, P2 1 ms) had equal initial voltages of Pt and P2. Two simulated single capacitor biphasic waveforms were also tested, the first designed to minimize the magnitude of P2 (P19 ms, P21 ms with initial voltage of P2 equal to 0.3 of the initial voltage of P1) and the second to maximize P2 (PI 5 ms, P2 5 ms with initial voltage of P2 = 0.5 PI).Alternating current was used to induce ventricular fibrillation and four trials of eight initial voltages from 100 to 800 V were performed for each of the four waveforms. Stepwise logistic regression was utilized to construct curves relating probability of successful defibrillation and energy.In the logistic model, the dual capacitor biphasic and single capacitor biphasic waveforms that maximized P2 were associated with significantly (p < 0.001) lower energy requirements for defibrillation than those of the monophasic waveform. The single capacitor biphasic waveform that minimized P2 was not significantly better than the monophasic waveform. The biphasic waveforms associated with the lowest energy requirements for defibrillation were characterized by a higher P2/PI energy ratio.These results demonstrate that single capacitor biphasic waveforms can be constructed that are superior to similar duration monophasic waveforms and comparable with some dual capacitor biphasic waveforms. The relative magnitude of PI and P2 appears to be an important determinant of defibrillation efficacy
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Integrated Geothermal Well Testing: Test Objectives and Facilities
A new and highly integrated geothermal well test program was designed for three geothermal operators in the US (MCR, RGI and Mapco Geothermal). This program required the design, construction and operation of new well test facilities. The main objectives of the test program and facilities are to investigate the critical potential and worst problems associated with the well and produced fluids in a period of approximately 30 days. Field and laboratory investigations are required to determine and quantify the problems of fluid production, utilization and reinjection. The facilities are designed to handle a flow rate from a geothermal well of one million pounds per hour at a wellhead temperature of approximately 268 C (515 F). The facilities will handle an entire spectrum of temperature and rate conditions up to these limits. All pertinent conditions for future fluid exploitations can be duplicated with these facilities, thus providing critical information at the very early stages of field development. The new well test facilities have been used to test high temperature, liquid-dominated geothermal wells in the Imperial Valley of California. The test facilities still have some problems which should be solvable. The accomplishments of this new and highly integrated geothermal well test program are described in this paper
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