44,742 research outputs found
A model of the near-earth plasma environment and application to the ISEE-A and -B orbit
A model of the near-earth environment to obtain a best estimate of the average flux of protons and electrons in the energy range from 0.1 to 100 keV for the International Sun-Earth Explorer (ISEE)-A and -B spacecraft. The possible radiation damage to the thermal coating on these spinning spacecraft is also studied. Applications of the model to other high-altitude satellites can be obtained with the appropriate orbit averaging. This study is the first attempt to synthesize an overall quantitative environment of low-energy particles for high altitude spacecraft, using data from in situ measurements
A simulation model for wind energy storage systems. Volume 1: Technical report
A comprehensive computer program for the modeling of wind energy and storage systems utilizing any combination of five types of storage (pumped hydro, battery, thermal, flywheel and pneumatic) was developed. The level of detail of Simulation Model for Wind Energy Storage (SIMWEST) is consistent with a role of evaluating the economic feasibility as well as the general performance of wind energy systems. The software package consists of two basic programs and a library of system, environmental, and load components. The first program is a precompiler which generates computer models (in FORTRAN) of complex wind source storage application systems, from user specifications using the respective library components. The second program provides the techno-economic system analysis with the respective I/O, the integration of systems dynamics, and the iteration for conveyance of variables. SIMWEST program, as described, runs on the UNIVAC 1100 series computers
Exact States in Waveguides With Periodically Modulated Nonlinearity
We introduce a one-dimensional model based on the nonlinear
Schrodinger/Gross-Pitaevskii equation where the local nonlinearity is subject
to spatially periodic modulation in terms of the Jacobi dn function, with three
free parameters including the period, amplitude, and internal form-factor. An
exact periodic solution is found for each set of parameters and, which is more
important for physical realizations, we solve the inverse problem and predict
the period and amplitude of the modulation that yields a particular exact
spatially periodic state. Numerical stability analysis demonstrates that the
periodic states become modulationally unstable for large periods, and regain
stability in the limit of an infinite period, which corresponds to a bright
soliton pinned to a localized nonlinearity-modulation pattern. Exact
dark-bright soliton complex in a coupled system with a localized modulation
structure is also briefly considered . The system can be realized in planar
optical waveguides and cigar-shaped atomic Bose-Einstein condensates.Comment: EPL, in pres
Embodied carbon and construction cost differences between Hong Kong and Melbourne buildings
Limiting the amount of embodied carbon in buildings can help minimize the damaging impacts of global warming through lower upstream emission of CO2. This study empirically investigates the embodied carbon footprint of new-build and refurbished buildings in both Hong Kong and Melbourne to determine the embodied carbon profile and its relationship to both embodied energy and construction cost. The Hong Kong findings suggest that mean embodied carbon for refurbished buildings is 33-39% lower than new-build projects, and the cost for refurbished buildings is 22-50% lower than new-build projects (per square metre of floor area). The Melbourne findings, however, suggest that mean embodied carbon for refurbished buildings is 4% lower than new-build projects, and the cost for refurbished buildings is 24% higher than new-build projects (per square metre of floor area). Embodied carbon ranges from 645-1,059 kgCO2e/m2 for new-build and 294-655 kgCO2e/m2 for refurbished projects in Hong Kong, and 1,138-1,705 kgCO2e/m2 for new-build and 900-1,681 kgCO2e/m2 for refurbished projects in Melbourne. The reasons behind these locational discrepancies are explored and critiqued. Overall, a very strong linear relationship between embodied energy and construction cost in both cities was found and can be used to predict the former, given the latter
Calibration of the ER-2 meteorological measurement system
The Meteorological Measurement System (MMS) on the high altitude ER-2 aircraft was developed specifically for atmospheric research. The MMS provides accurate measurements of pressure, temperature, wind vector, position (longitude, latitude, altitude), pitch, roll, heading, angle of attack, angle of sideslip, true airspeed, aircraft eastward velocity, northward velocity, vertical acceleration, and time, at a sample rate of 5/s. MMS data products are presented in the form of either 5 or 1 Hz time series. The 1 Hz data stream, generally used by ER-2 investigators, is obtained from the 5 Hz data stream by filtering and desampling. The method of measurement of the meteorological parameters is given and the results of their analyses are discussed
A mini-array for large air showers
A mini-array that utilizes the Linsley effect is proposed for the measurement of large air showers. An estimate of the detectable shower rates for various shower sizes is made. Details of the detection and data collection systems are also described
Transverse Entanglement Migration in Hilbert Space
We show that, although the amount of mutual entanglement of photons
propagating in free space is fixed, the type of correlations between the
photons that determine the entanglement can dramatically change during
propagation. We show that this amounts to a migration of entanglement in
Hilbert space, rather than real space. For the case of spontaneous parametric
down conversion, the migration of entanglement in transverse coordinates takes
place from modulus to phase of the bi-photon state and back again. We propose
an experiment to observe this migration in Hilbert space and to determine the
full entanglement.Comment: 4 pages, 3 figure
Kinetics and mechanism of formic acid decomposition on Ru(001)
The steady-state rate of decomposition of formic acid on
Ru(001) has been measured as a function of surface temperature, parametric in the pressure of formic acid. The
products of the decomposition reaction are C0_2, H_2, CO,
and H_2)0, i.e., both dehydrogenation and dehydration occur
on Ru (001). A similar product distribution has been observed on Ni(110), Ni(100), Ru(100), Fe(100), and
Ni(111) surfaces; whereas only dehydrogenation to C0_2
and H_2 occurs on the Cu(100), Cu(110), and Pt(111)
surfaces. Only reversible adsorption and desorption of formic acid is observed on the less reactive Ag(110) surface at low temperatures, whereas the more reactive Mo(100) surface is oxidized by formic acid at low temperatures with the products of this reaction being H_2, CO, and H_(2)O (Ref. 10). We report here the confirmation of earlier observations of the occurrence of both dehydrogenation and dehydration of formic acid on Ru(001), and more importantly, we provide a detailed mechanistic description of the steady-state decomposition reaction on this surface in terms of elementary steps
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