1,953 research outputs found
Computed Tomography in Abdominal Imaging: How to Gain Maximum Diagnostic Information at the Lowest Radiation Dose
Medium Effects on Binary Collisions with the Delta Resonance
To facilitate the relativistic heavy-ion calculations based on transport
equations, the binary collisions involving a resonance in either the
entrance channel or the exit channel are investigated within a Hamiltonian
formulation of interactions. An averaging procedure is developed to
define a quasi-particle and to express the experimentally measured
cross section in terms of an effective cross section. In contrast to previous works, the main feature of
the present approach is that the mass and the momentum of the produced
's are calculated dynamically from the bare vertex interaction of the model Hamiltonian and are constrained by the
unitarity condition. The procedure is then extended to define the effective
cross sections for the experimentally inaccessible and reactions. The predicted cross
sections are significantly different from what are commonly assumed in
relativistic heavy-ion calculations. The potential in nuclear matter
has been calculated by using a Bruckner-Hartree-Fock approximation. By
including the mean-field effects on the propagation, the effective
cross sections of the , and reactions in nuclear matter are
predicted. It is demonstrated that the density dependence is most dramatic in
the energy region close to the pion production threshold.Comment: 20 pages, RevTe
Autonomous docking ground demonstration (category 3)
The NASA Johnson Space Center (JSC) is involved in the development of an autonomous docking ground demonstration. The demonstration combines the technologies, expertise and facilities of the JSC Tracking and Communications Division (EE), Structures and Mechanics Division (ES), and the Navigation, Guidance and Control Division (EG) and their supporting contractors. The autonomous docking ground demonstration is an evaluation of the capabilities of the laser sensor system to support the docking phase (12ft to contact) when operated in conjunction with the Guidance, Navigation and Control Software. The docking mechanism being used was developed for the Apollo Soyuz Test Program. This demonstration will be conducted using the Six-Degrees of Freedom (6-DOF) Dynamic Test System (DTS). The DTS environment simulates the Space Station Freedom as the stationary or target vehicle and the Orbiter as the active or chase vehicle. For this demonstration the laser sensor will be mounted on the target vehicle and the retroreflectors on the chase vehicle. This arrangement was used to prevent potential damage to the laser. The sensor system. GN&C and 6-DOF DTS will be operated closed-loop. Initial condition to simulate vehicle misalignments, translational and rotational, will be introduced within the constraints of the systems involved. Detailed description of each of the demonstration components (e.g., Sensor System, GN&C, 6-DOF DTS and supporting computer configuration) including their capabilities and limitations will be discussed. A demonstration architecture drawing and photographs of the test configuration will be presented
Brief of Fred T. Korematsu Center for Law and Equality as Amicus Curiae in Support of Petitioners
State of Washington v. Anthony A. Moretti, Hung Van Nguyen, and Frederick Or
Brief of Fred T. Korematsu Center for Law and Equality as Amicus Curiae in Support of Petitioner
State of Washington v. Jeremiah James Gilber
Brief of Fred T. Korematsu Center for Law and Equality, American Civil Liberties Union of Washington, Washington Association of Criminal Defense Lawyers, and Washington Defender Association as Amici Curiae in Support of Respondent
State of Washington v. Cristian Delbosqu
Integralni pristup sustavima energetske elektronike
Today\u27s power electronics systems are typically manufactured using non-standard parts, resulting in labor-intensive manufacturing processes, increased cost and poor reliability. As a possible way to overcome these problems, this paper discusses an integrated approach to design and manufacture power electronics systems to improve performance, reliability and cost effectiveness. Addressed in the paper are the technologies being developed for integration of both power supplies and motor drives. These technologies include the planar metalization to eliminate bonding wires, the integration of power passives, the integration of current sensors, the development of power devices to facilitate integration as well as to improve performance, and the integration of necessary CAD tools to address the multidisciplinary aspects of integrated systems. The development of Integrated Power Electronics Modules (IPEMs) is demonstrated for two applications: (1) 1 kW asymmetrical half-bridge DC-DC converter and (2) 1–3 kW motor drive for heating, ventilation and air conditioning (HVAC). Electrical and thermal design tradeoffs of IPEMs and related enabling technologies are described in the paper.Današnji sustavi energetske elektronike se obično proizvode iz nestandardnih dijelova. Posljedica toga je laboratorijska proizvodnja elektroničkih učinskih pretvarača, povećani troškovi i smanjena pouzdanost. Jedan od mogućih načina prevladavanja ovih poteškoća jest integralni pristup projektiranju i proizvodnji sustava energetske elektronike. Posebice se razmatraju tehnologije razvijene za integraciju učinskih krugova i motora. Ove tehnologije uključuju postupke planarne metalizacije za izbjegavanje žičanih vodova, integraciju pasivnih dijelova učinskih krugova, integraciju strujnih senzora, te razvoj takvih poluvodičkih komponenata koje olakšavaju integraciju i poboljšavaju karakteristike uređaja. Pri projektiranju, zbog multidisciplinarnih aspekata integriranih sustava, treba primijeniti nužne CAD alate. Razvoj integriranih modula elektroničkih učinskih pretvarača (engl. integrated power electronics modules, IPEM) ilustriran je na dvije primjene: (1) istosmjerni pretvarač snage 1 kW u asimetričnom polumosnom spoju i (2) elektromotorni pogon snage 1 . . . 3 kW za grijanje, ventilaciju i klimatizaciju (engl. heating, ventilation and air conditioning, HVAC). Na IPEM-u objašnjeni su projektantski i tehnološki kompromisi električkog i toplinskog projekta
- …