369 research outputs found
Requirements for a transformerless power conditioning system
Requirements for development of a Transformerless Power Conditioning Subsystem (TPCS) that will meet utility, manufacturer, and customer needs are detailed. Issues analyzed include current utility guidelines, safety and grounding issues that appear as local codes, various kinds of TPCS connections that can be developed, dc injection, and a brief survey of TPCS circuit topologies that will meet requirements. The major result is that a finite time exists for control operation before dc injection into the distribution transformer causes customer outage (on the order of seconds). This time permits the control system to sense a dc injection condition and remove the TPCS from the utility system. Requirements for such a control system are specified. A three wire connection will ensure balanced operation for customer loads and two wire connections caused average value dc to be injected into single phase loads. This type of connection also allows for the lowest array voltage. The conclusion is that requirements for a TPCS can be determined and that there are not showstopping issues preventing implementation. The actual design and topology of the TPCS was left for further study
Letter From Lewis A. Kalbach to Francis Mairs Huntington-Wilson, February 27, 1918
A typed letter by Lewis Kalbach to Francis Mairs Huntington-Wilson, dated February 27, 1918. Within, Kalbach writes to acknowledge that Philander Claxton\u27s office had received Wilson\u27s prior letter containing his War of the Unborn essay.https://digitalcommons.ursinus.edu/fmhw_firstworldwar_documents/1076/thumbnail.jp
Prioritisation, resources and search terms: a study of decision-making at the virtual reference desk.
The reinterpretation of the traditional reference service in an online context is the virtual reference desk. Placing reference services into an online setting, however, presents many challenges. We report a study and analytic framework which addresses support for decision-making during virtual enquiry work. Focusing on specialist law-libraries, the study shows that enquirers do not volunteer important information to the service and that asynchronous communication media and some social obstacles present barriers to prompting. Also, previous enquiries are frequently used to inform current enquiry strategies but barriers exist in accessing this information. We conclude that email is an inadequate medium for supporting virtual reference services, and that system should support automatic, speculative matching between new enquiry content and integrated enquiry knowledge bases. The contribution of the framework is to offer a structured approach to evaluation in multiple virtual reference contexts and enable rapid convergence on barriers to efficient and effective service
Excitation functions of proton induced nuclear reactions on natW up to 40 MeV
Excitation functions for the production of the 181,182m,182g,183,184g,186Re
and 183,184Ta radionuclides from proton bombardment on natural tungsten were
measured using the stacked-foil activation technique for the proton energies up
to 40 MeV. A new data set has been given for the formation of the investigated
radionuclides. Results are in good agreement with the earlier reported
experimental data and theoretical calculations based on the ALICE-IPPE code.
The thick target integral yields were also deduced from the measured excitation
functions. The deduced yield values were compared with the directly measured
thick target yield (TTY), and found acceptable agreement. The investigated
radionuclide 186Re has remarkable applications in the field of nuclear
medicine, whereas the data of 183,184gRe and 183Ta have potential applications
in thin layer activation analysis and biomedical tracer studies, respectively.Comment: 21papes, 14 figure
Fast-neutron induced pre-equilibrium reactions on 55Mn and 63,65Cu at energies up to 40 MeV
Excitation functions were measured for the Mn(n,2n)Mn,
Mn(n,)V, Cu(n,)Co,
Cu(n,2n)Cu, and Cu(n,p)Ni reactions from 13.47 to
14.83 MeV. The experimental cross sections are compared with the results of
calculations including all activation channels for the stable isotopes of Mn
and Cu, for neutron incident energies up to 50 MeV. Within the energy range up
to 20 MeV the model calculations are most sensitive to the parameters related
to nuclei in the early stages of the reaction, while the model assumptions are
better established by analysis of the data in the energy range 20-40 MeV. While
the present analysis has taken advantage of both a new set of accurate measured
cross sections around 14 MeV and the larger data basis fortunately available
between 20 and 40 MeV for the Mn and Cu isotopes, the need of additional
measurements below as well as above 40 MeV is pointed out. Keywords: 55Mn,
63,65Cu, E40 MeV, Neutron activation cross section measurements, Nuclear
reactions, Model calculations, Manganese, CopperComment: 39 pages, 12 figure
Particle-hole state densities with non-equidistant single-particle levels
The correct use of energy-dependent single-particle level (s.p.l.) densities
within particle-hole state densities based on the equidistant spacing model
(ESM) is analysed. First, an analytical expression is obtained following the
convolution of energy-dependent excited-particle and hole densities. Next, a
comparison is made with results of the ESM formula using average s.p.l.
densities for the excited particles and holes, respectively. The Fermi-gas
model (FGM) s.p.l. densities calculated at the corresponding average excitation
energies are used in both cases. The analysis concerns also the density of
particle-hole bound states. The pairing correlations are taken into account
while the comparison of various effects includes the exact correction for the
Pauli exclusion principle. Quantum-mechanical s.p.l. densities and the
continuum effect can also match a corresponding FGM formula, suitable for use
within the average energy-dependent partial state density in multistep reaction
models.Comment: 29 pages, ReVTeX, 11 postscript figures, submitted to Phys.Rev.
Implementation of a new energy-angular distribution of particles emitted by deuteron induced nuclear reaction in transport simulations
How potential users of music search and retrieval systems describe the semantic quality of music
Nucleon-induced reactions at intermediate energies: New data at 96 MeV and theoretical status
Double-differential cross sections for light charged particle production (up
to A=4) were measured in 96 MeV neutron-induced reactions, at TSL laboratory
cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U,
were performed using two independent devices, SCANDAL and MEDLEY. The data were
recorded with low energy thresholds and for a wide angular range (20-160
degrees). The normalization procedure used to extract the cross sections is
based on the np elastic scattering reaction that we measured and for which we
present experimental results. A good control of the systematic uncertainties
affecting the results is achieved. Calculations using the exciton model are
reported. Two different theoretical approches proposed to improve its
predictive power regarding the complex particle emission are tested. The
capabilities of each approach is illustrated by comparison with the 96 MeV data
that we measured, and with other experimental results available in the
literature.Comment: 21 pages, 28 figure
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