18,624 research outputs found
NASTRAN migration to UNIX
COSMIC/NASTRAN, as it is supported and maintained by COSMIC, runs on four main-frame computers - CDC, VAX, IBM and UNIVAC. COSMIC/NASTRAN on other computers, such as CRAY, AMDAHL, PRIME, CONVEX, etc., is available commercially from a number of third party organizations. All these computers, with their own one-of-a-kind operating systems, make NASTRAN machine dependent. The job control language (JCL), the file management, and the program execution procedure of these computers are vastly different, although 95 percent of NASTRAN source code was written in standard ANSI FORTRAN 77. The advantage of the UNIX operating system is that it has no machine boundary. UNIX is becoming widely used in many workstations, mini's, super-PC's, and even some main-frame computers. NASTRAN for the UNIX operating system is definitely the way to go in the future, and makes NASTRAN available to a host of computers, big and small. Since 1985, many NASTRAN improvements and enhancements were made to conform to the ANSI FORTRAN 77 standards. A major UNIX migration effort was incorporated into COSMIC NASTRAN 1990 release. As a pioneer work for the UNIX environment, a version of COSMIC 89 NASTRAN was officially released in October 1989 for DEC ULTRIX VAXstation 3100 (with VMS extensions). A COSMIC 90 NASTRAN version for DEC ULTRIX DECstation 3100 (with RISC) is planned for April 1990 release. Both workstations are UNIX based computers. The COSMIC 90 NASTRAN will be made available on a TK50 tape for the DEC ULTRIX workstations. Previously in 1988, an 88 NASTRAN version was tested successfully on a SiliconGraphics workstation
Surface Impedance and Bulk Band Geometric Phases in One-Dimensional Systems
Surface impedance is an important concept in classical wave systems such as
photonic crystals (PCs). For example, the condition of an interface state
formation in the interfacial region of two different one-dimensional PCs is
simply Z_SL +Z_SR=0, where Z_SL (Z_SR)is the surface impedance of the
semi-infinite PC on the left- (right-) hand side of the interface. Here, we
also show a rigorous relation between the surface impedance of a
one-dimensional PC and its bulk properties through the geometrical (Zak) phases
of the bulk bands, which can be used to determine the existence or
non-existence of interface states at the interface of the two PCs in a
particular band gap. Our results hold for any PCs with inversion symmetry,
independent of the frequency of the gap and the symmetry point where the gap
lies in the Brillouin Zone. Our results provide new insights on the
relationship between surface scattering properties, the bulk band properties
and the formation of interface states, which in turn can enable the design of
systems with interface states in a rational manner
Microscopic Investigation of Vortex Breakdown in a Dividing T-Junction Flow
3D-printed microfluidic devices offer new ways to study fluid dynamics. We
present the first clear visualization of vortex breakdown in a dividing
T-junction flow. By individual control of the inflow and two outflows, we
decouple the effects of swirl and rate of vorticity decay. We show that even
slight outflow imbalances can greatly alter the structure of vortex breakdown,
by creating a net pressure difference across the junction. Our results are
summarized in a dimensionless phase diagram, which will guide the use of vortex
breakdown in T-junctions to achieve specific flow manipulation.Comment: 5 pages, 5 figure
A systematic review comparing the functional changes and complications of DIEP and TRAM flaps in patients receiving breast reconstruction
Aim: Treatment for breast cancer may involve unilateral or bilateral mastectomy, with subsequent breast reconstruction surgery. Using autologous tissue flaps during reconstructive surgery is increasingly popular. The aim of this systematic review was to determine if the DIEP flap is more effective than the TRAM flap for breast reconstruction in females after a mastectomy in terms of donor site morbidity, recipient site morbidity, and functional outcome.
Methods: Studies were identified using the databases Medline and Embase and applying predefined search criteria. The limits applied were; peer-reviewed, published between January 1980 to May 2013, human trials, English language. Study inclusion followed a review of the title, abstract, and full text by two independent researchers.
Results: Two trends were identified. 1) DIEP flap surgery reduces the risk of abdominal weakness without increasing the risk of flap complications if performed by a surgeon well trained in microsurgery; 2) TRAM flap surgery remains a good alternative due to its evolution towards muscle-sparing techniques.
Conclusion: This appears to be the first systematic review in this area of research. The evidence demonstrates that DIEP flap reduces postoperative abdominal morbidity, with no increased flap complication compared to the TRAM flap if performed by a surgeon well trained in microsurgery
Adaptive Image Denoising by Targeted Databases
We propose a data-dependent denoising procedure to restore noisy images.
Different from existing denoising algorithms which search for patches from
either the noisy image or a generic database, the new algorithm finds patches
from a database that contains only relevant patches. We formulate the denoising
problem as an optimal filter design problem and make two contributions. First,
we determine the basis function of the denoising filter by solving a group
sparsity minimization problem. The optimization formulation generalizes
existing denoising algorithms and offers systematic analysis of the
performance. Improvement methods are proposed to enhance the patch search
process. Second, we determine the spectral coefficients of the denoising filter
by considering a localized Bayesian prior. The localized prior leverages the
similarity of the targeted database, alleviates the intensive Bayesian
computation, and links the new method to the classical linear minimum mean
squared error estimation. We demonstrate applications of the proposed method in
a variety of scenarios, including text images, multiview images and face
images. Experimental results show the superiority of the new algorithm over
existing methods.Comment: 15 pages, 13 figures, 2 tables, journa
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