14,375 research outputs found
Multicomputer communication system
A local area network is provided for a plurality of autonomous computers which operate at different rates and under different protocols coupled by network bus adapters to a global bus. A host computer (HC) divides a message file to be transmitted into blocks, each with a header that includes a data type identifier and a trailer. The associated network bus adapter (NBA) then divides the data into packets, each with a header to which a transport header and trailer is added with frame type code which specifies one of three modes of addressing in the transmission of data, namely a physical address mode for computer to computer transmission using two bytes for source and destination addresses, a logical address mode and a data type mode. In the logical address mode, one of the two addressing bytes contains a logical channel number (LCN) established between the transmitting and one or more receiving computers. In the data type mode, one of the addressing bytes contains a code identifying the type of data
Consequences of self-consistency violations in Hartree-Fock random-phase approximation calculations of the nuclear breathing mode energy
We provide for the first time accurate assessments of the consequences of
violations of self-consistency in the Hartree-Fock based random phase
approximation (RPA) as commonly used to calculate the energy of the
nuclear breathing mode. Using several Skyrme interactions we find that the
self-consistency violated by ignoring the spin-orbit interaction in the RPA
calculation causes a spurious enhancement of the breathing mode energy for spin
unsaturated systems. Contrarily, neglecting the Coulomb interaction in the RPA
or performing the RPA calculations in the TJ scheme underestimates the
breathing mode energy. Surprisingly, our results for the Zr and
Pb nuclei for several Skyrme type effective nucleon-nucleon
interactions having a wide range of nuclear matter incompressibility ( MeV) and symmetry energy ( MeV) indicate that
the net uncertainty ( MeV) is comparable to the
experimental one.Comment: Revtex file (11 pages), Accepted for the publication in Phys. Rev.
Feasibility and benefits of laminar flow control on supersonic cruise airplanes
An evaluation was made of the applicability and benefits of laminar flow control (LFC) technology to supersonic cruise airplanes. Ancillary objectives were to identify the technical issues critical to supersonic LFC application, and to determine how those issues can be addressed through flight and wind-tunnel testing. Vehicle types studied include a Mach 2.2 supersonic transport configuration, a Mach 4.0 transport, and two Mach 2-class fighter concepts. Laminar flow control methodologies developed for subsonic and transonic wing laminarization were extended and applied. No intractible aerodynamic problems were found in applying LFC to airplanes of the Mach 2 class, even ones of large size. Improvements of 12 to 17 percent in lift-drag ratios were found. Several key technical issues, such as contamination avoidance and excresence criteria were identified. Recommendations are made for their resolution. A need for an inverse supersonic wing design methodology is indicated
Constraining the density dependence of symmetry energy from nuclear masses
Empirically determined values of the nuclear volume and surface symmetry
energy coefficients from nuclear masses are expressed in terms of density
distributions of nucleons in heavy nuclei in the local density approximation.
This is then used to extract the value of the symmetry energy slope parameter
. The density distributions in both spherical and well deformed nuclei
calculated within microscopic framework with different energy density
functionals give MeV. Application of the method also helps
in a precision determination of the neutron skin thickness of nuclei that are
difficult to measure accurately.Comment: 6 pages including 3 figures, accepted in Phys. Rev. C (Rapid Comm.
Numerical simulation of bubble growth in film boiling using a coupled level-set and volume-of-fluid method
A coupled level-set and volume-of-fluid method is presented for modeling incompressible two-phase flows with surface tension. The coupled algorithm conserves mass and captures the complicated interfaces very accurately. A planar simulation of bubble growth is performed in water at near critical pressure for different degrees of superheat. The effect of superheat on the frequency of bubble formation has been analyzed. In addition, simulation of film boiling and bubble formation is performed in refrigerant R134a at near critical and far critical pressures. The effect of saturation pressure on the frequency of bubble formation has also been studied. A deviation from the periodic bubble release is observed in the case of superheat beyond 15 K in water. The effect of heat flux on the instability has also been analyzed. It is found that for water at near critical condition, a decrease in superheat from 15 to 10 K leads to oscillations with subharmonics influencing the time period of the ebullition cycle
Techniques for the Synthesis of Reversible Toffoli Networks
This paper presents novel techniques for the synthesis of reversible networks
of Toffoli gates, as well as improvements to previous methods. Gate count and
technology oriented cost metrics are used. Our synthesis techniques are
independent of the cost metrics. Two new iterative synthesis procedure
employing Reed-Muller spectra are introduced and shown to complement earlier
synthesis approaches. The template simplification suggested in earlier work is
enhanced through introduction of a faster and more efficient template
application algorithm, updated (shorter) classification of the templates, and
presentation of the new templates of sizes 7 and 9. A novel ``resynthesis''
approach is introduced wherein a sequence of gates is chosen from a network,
and the reversible specification it realizes is resynthesized as an independent
problem in hopes of reducing the network cost. Empirical results are presented
to show that the methods are effective both in terms of the realization of all
3x3 reversible functions and larger reversible benchmark specifications.Comment: 20 pages, 5 figure
Fermionic bright soliton in a boson-fermion mixture
We use a time-dependent dynamical mean-field-hydrodynamic model to study the
formation of fermionic bright solitons in a trapped degenerate Fermi gas mixed
with a Bose-Einstein condensate in a quasi-one-dimensional cigar-shaped
geometry. Due to a strong Pauli-blocking repulsion among spin-polarized
fermions at short distances there cannot be bright fermionic solitons in the
case of repulsive boson-fermion interactions. However, we demonstrate that
stable bright fermionic solitons can be formed for a sufficiently attractive
boson-fermion interaction in a boson-fermion mixture. We also consider the
formation of fermionic solitons in the presence of a periodic axial
optical-lattice potential. These solitons can be formed and studied in the
laboratory with present technology.Comment: 7 pages, 7 ps figure
Stability and decay of Bloch oscillations in presence of time-dependent nonlinearity
We consider Bloch oscillations of Bose-Einstein condensates in presence of a
time-modulated s-wave scattering length. Generically, interaction leads to
dephasing and decay of the wave packet. Based on a cyclic-time argument, we
find---additionally to the linear Bloch oscillation and a rigid soliton
solution---an infinite family of modulations that lead to a periodic time
evolution of the wave packet. In order to quantitatively describe the dynamics
of Bloch oscillations in presence of time-modulated interactions, we employ two
complementary methods: collective-coordinates and the linear stability analysis
of an extended wave packet. We provide instructive examples and address the
question of robustness against external perturbations.Comment: 15 pages, 8 figures. Slightly amended final versio
Head injury at a tertiary referral centre in the Eastern Region of Nepal
Background: The purpose of this epidemiologic study was to determine the pattern and characteristics of head injuries and to establish an epidemiologic data bank for designing preventive strategies for head injuries in the eastern region of Nepal.Patients and Methods: This retrospective review was done at B.P.Koirala institute of Health Sciences, Dharan, Nepal. All the patients with head injury admitted to the Department of Surgery between the periods January 2005 to December 2005 were included in the study.Results: The study population consisted of 334 patients who sustained head injuries. Their ages ranged from 1 to 88 with a mean age of 28.53 years. The majority (66.3%), were young adults in the 2nd to 5th decades The male to female sex ratio was 2.6:1. Road traffic crushes were the most common cause (43.4%) followed by fall from heights (30.8%). X-ray of skull showed lesions in 114 cases (49.8%) such as depressed fracture (11.4%) and linear fracture (24.0%). Common lesions on CT scan included cerebral contusion (21.6%), extradural haematoma (20.9%), linear fracture (23.8%), subarachnoid haemorrhage (18.5%) and pnemocephalus (11.2%). Forty patients (12.0%) sustained moderate head injury. There were 15 deaths. One patient had associated intra-abdominal injury (splenic rupture) and two patient sustained pulmonary trauma and succumbed to haemothorax and aspiration.Conclusion: A clearer understanding of the patterns of head injuries will assist health care providers to plan and manage the treatment of traumatic facial injuries. Such epidemiological information can also be used to guide the future funding of public health programs geared toward prevention
Observation of asymmetric spectrum broadening induced by silver nanoparticles in a heavy-metal oxide glass
We demonstrate experimentally and support by a theoretical analysis an effect
of asymmetric spectrum broadening, which results from doping of silver
nanoparticles into a heavy-glass matrix, 90(0.5WO3-0.3SbPO4-0.2PbO)-10AgCl. The
strong dispersion of the effective nonlinear coefficient of the composite
significantly influences the spectral broadening via the self-phase modulation,
and leads to a blue upshift of the spectrum. Further extension of the spectrum
towards shorter wavelengths is suppressed by a growing loss caused by the
plasmon resonance in the silver particles. The red-edge spectral broadening is
dominated by the stimulated Raman Scattering.Comment: Accepted for publishing epl13477; EPL Journal 201
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