2,947 research outputs found
A comparison of a statistical-mechanics based plasticity model with discrete dislocation plasticity calculations
A two-dimensional nonlocal version of continuum crystal plasticity theory is proposed, which is based on a statistical-mechanics description of the collective behavior of dislocations coupled to standard small-strain crystal continuum kinematics for single slip. It involves a set of transport equations for the total dislocation density field and for the net-Burgers vector density field, which include a slip system back stress associated to the gradient of the net-Burgers vector density. The theory is applied to the problem of shearing of a two-dimensional composite material with elastic reinforcements in a crystalline matrix. The results are compared to those of discrete dislocation simulations of the same problem. The continuum theory is shown to be able to pick up the distinct dependence on the size of the reinforcing particles for one of the morphologies being studied. Also, its predictions are consistent with the discrete dislocation results during unloading, showing a pronounced Bauschinger effect. None of these features are captured by standard local plasticity theories. (C) 2003 Elsevier Ltd. All rights reserved
Interaction and Localization of One-electron Orbitals in an Organic Molecule: Fictitious Parameter Analysis for Multi-physics Simulations
We present a new methodology to analyze complicated multi-physics simulations
by introducing a fictitious parameter. Using the method, we study quantum
mechanical aspects of an organic molecule in water. The simulation is
variationally constructed from the ab initio molecular orbital method and the
classical statistical mechanics with the fictitious parameter representing the
coupling strength between solute and solvent. We obtain a number of
one-electron orbital energies of the solute molecule derived from the
Hartree-Fock approximation, and eigenvalue-statistical analysis developed in
the study of nonintegrable systems is applied to them. Based on the results, we
analyze localization properties of the electronic wavefunctions under the
influence of the solvent.Comment: 4 pages, 5 figures, the revised version will appear in J. Phys. Soc.
Jpn. Vol.76 (No.1
Self-Assembly of Supramolecules Consisting of Octyl Gallate Hydrogen Bonded to Polyisoprene-block-poly(vinylpyridine) Diblock Copolymers
Synchrotron radiation was used to investigate the self-assembly in two comb-shaped supramolecules systems consisting of octyl gallate (OG), i.e., 1-octyl-3,4,5-trihydroxybenzoate, hydrogen bonded to the pyridine groups of polyisoprene-block-poly(vinylpyridine) diblock copolymers. In the case of the 1,2-polyisoprene-block-poly(4-vinylpyridine)(OG)x system, self-assembly was only observed for x ≥0.5, where x denotes the number of OG molecules per pyridine group. For x = 0.5, 0.75, 1.0, and 1.2 the system self-assembled in the form of hexagonally ordered cylinders of P4VP(OG) throughout the entire temperature range of 25-200 °C investigated. For the 1,4-polyisoprene-block-poly(2-vinylpyridine)(OG)x system, on the other hand, a considerably more complex phase behavior was found, including the formation of cubic, hexagonally ordered cylinders and lamellar morphologies. In this case several order-order transitions were observed as a function of temperature, including a lamellar to lamellar transition involving a collapse of the layer thickness. The absence of hydrogen bonding between the octyl gallate molecules and the pyridine groups at elevated temperatures is argued to be a key factor for many of the phenomena observed.
Sub-Chronic Administration of Aqueous Leaf Extract of Ficus Sycomorus on some Liver and Kidney Function Indices in Rats
The stem bark of Ficus sycomorus is used traditionally for cure of fungal infection, jaundice and dysentery in some parts of northern Nigeria. The leaves of Ficus sycomorus were collected, dried and extracted to screen for some phytochemicals and study its effect on liver and kidney functions in experimental rats. Phytochemical screening of leaf extract of F. sycomorus indicates the presence of alkaloids, tannins, saponins, flavonoids and reducing sugars. Animals were divided into two sets (A&B) of five groups each and were administered 0.00, 200, 400, 800 and 1600 mgkg-1 body weight of the aqueous leaf extract for 14 days orally with set A administered once daily and set B administered twice daily. Serum activities of ALT, AST, ALP and concentration of urea and creatinine of both sets show no significant difference (p<0.05) compared to the control group; except in ALP (148.00±0.77 and 175.80±0.45U/L) and urea (41.20±0.09 and 53.38±0.17mg/dL) at higher doses (1600mgkg-1) of the extract. Base on this study, the extract show neither liver nor kidney toxicity, however, it should be use with caution especially at higher dose and long time exposure.Keyword: Ficus sycomorus, phytochemical screening, kidney indices, liver indices
HetFS: A heterogeneous file system for everyone
Storage devices have been getting more and more diverse during the last decade. The advent of SSDs made it painfully clear that rotating devices, such as HDDs or magnetic tapes, were lacking in regards to response time. However, SSDs currently have a limited number of write cycles and a significantly larger price per capacity, which has prevented rotational technologies from begin abandoned. Additionally, Non-Volatile Memories (NVMs) have been lately gaining traction, offering devices that typically outperform NAND-based SSDs but exhibit a full new set of idiosyncrasies.
Therefore, in order to appropriately support this diversity, intelligent mechanisms will be needed in the near-future to balance the benefits and drawbacks of each storage technology available to a system. In this paper, we present a first step towards such a mechanism called HetFS, an extension to the ZFS file system that is capable of choosing the storage device a file should be kept in according to preprogrammed filters. We introduce the prototype and show some preliminary results of the effects obtained when placing specific files into different devices.The research leading to these results has received funding from the European
Community under the BIGStorage ETN (Project 642963 of the H2020-MSCA-ITN-2014), by the Spanish Ministry of Economy and Competitiveness under
the TIN2015-65316 grant and by the Catalan Government under the 2014-SGR-
1051 grant. To learn more about the BigStorage project, please visit http:
//bigstorage-project.eu/.Peer ReviewedPostprint (author's final draft
Alterations in fuel homeostasis in adult male rats by perinatal poly-unsaturated fatty acid supplementation are insulin-dependent
Dielectric and thermal relaxation in the energy landscape
We derive an energy landscape interpretation of dielectric relaxation times
in undercooled liquids, comparing it to the traditional Debye and
Gemant-DiMarzio-Bishop pictures. The interaction between different local
structural rearrangements in the energy landscape explains qualitatively the
recently observed splitting of the flow process into an initial and a final
stage. The initial mechanical relaxation stage is attributed to hopping
processes, the final thermal or structural relaxation stage to the decay of the
local double-well potentials. The energy landscape concept provides an
explanation for the equality of thermal and dielectric relaxation times. The
equality itself is once more demonstrated on the basis of literature data for
salol.Comment: 7 pages, 3 figures, 41 references, Workshop Disordered Systems,
Molveno 2006, submitted to Philosophical Magazin
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Assessment of RELAP5/MOD3.1 for gravity-driven injection experiment in the core makeup tank of the CARR Passive Reactor (CP-1300)
The objective of the present work is to improve the analysis capability of RELAP5/MOD3.1 on the direct contact condensation in the core makeup tank (CMT) of passive high-pressure injection system (PHPIS) in the CARR Passive Reactor (CP-1300). The gravity-driven injection experiment is conducted by using a small scale test facility to identify the parameters having significant effects on the gravity-driven injection and the major condensation modes. It turns out that the larger the water subcooling is, the more initiation of injection is delayed, and the sparger and the natural circulation of the hot water from the steam generator accelerate the gravity-driven injection. The condensation modes are divided into three modes: sonic jet, subsonic jet, and steam cavity. RELAP5/MOD3.1 is chosen to evaluate the cod predictability on the direct contact condensation in the CMT. It is found that the predictions of MOD3.1 are in better agreement with the experimental data than those of MOD3.0. From the nodalization study of the test section, the 1-node model shows better agreement with the experimental data than the multi-node models. RELAP5/MOD3.1 identifies the flow regime of the test section as vertical stratification. However, the flow regime observed in the experiment is the subsonic jet with the bubble having the vertical cone shape. To accurately predict the direct contact condensation in the CMT with RELAP5/MOD3.1, it is essential that a new set of the interfacial heat transfer coefficients and a new flow regime map for direct contact condensation in the CMT be developed
Electronic stress tensor analysis of hydrogenated palladium clusters
We study the chemical bonds of small palladium clusters Pd_n (n=2-9)
saturated by hydrogen atoms using electronic stress tensor. Our calculation
includes bond orders which are recently proposed based on the stress tensor. It
is shown that our bond orders can classify the different types of chemical
bonds in those clusters. In particular, we discuss Pd-H bonds associated with
the H atoms with high coordination numbers and the difference of H-H bonds in
the different Pd clusters from viewpoint of the electronic stress tensor. The
notion of "pseudo-spindle structure" is proposed as the region between two
atoms where the largest eigenvalue of the electronic stress tensor is negative
and corresponding eigenvectors forming a pattern which connects them.Comment: 22 pages, 13 figures, published online, Theoretical Chemistry
Account
Measurements of scattering observables for the break-up reaction
High-precision measurements of the scattering observables such as cross
sections and analyzing powers for the proton-deuteron elastic and break-up
reactions have been performed at KVI in the last two decades and elsewhere to
investigate various aspects of the three-nucleon force (3NF) effects
simultaneously. In 2006 an experiment was performed to study these effects in
break-up reaction at 135 MeV with the detection system, Big
Instrument for Nuclear polarization Analysis, BINA. BINA covers almost the
entire kinematical phase space of the break-up reaction. The results are
interpreted with the help of state-of-the-art Faddeev calculations and are
partly presented in this contribution.Comment: Proceedings of 19th International IUPAP Conference on Few-Body
Problems in Physics, Bonn University, 31.08 - 05.09.2009, Bonn, GERMAN
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