451 research outputs found
Ground-State Properties of a One-Dimensional System of Hard Rods
A quantum Monte Carlo simulation of a system of hard rods in one dimension is
presented and discussed. The calculation is exact since the analytical form of
the wavefunction is known, and is in excellent agreement with predictions
obtained from asymptotic expansions valid at large distances. The analysis of
the static structure factor and the pair distribution function indicates that a
solid-like and a gas-like phases exist at high and low densities, respectively.
The one-body density matrix decays following a power-law at large distances and
produces a divergence in the low density momentum distribution at k=0 which can
be identified as a quasi-condensate.Comment: 4 pages, 4 figure
4He adsorbed inside (10,10) single walled carbon nanotubes
Diffusion Monte Carlo calculations on the adsorption of He in open-ended
single walled (10,10) nanotubes are presented. We have found a first order
phase transition separating a low density liquid phase in which all He
atoms are adsorbed close to the tube wall and a high density arrangement
characterized by two helium concentric layers. The energy correction due to the
presence of neighboring tubes in a bundle has also been calculated, finding it
negligible in the density range considered.Comment: 5 pages, accepted for publication in Phys. Rev.
The free surface of superfluid 4He at zero temperature
The structure and energetics of the free surface of superfluid He are
studied using the diffusion Monte Carlo method. Extending a previous
calculation by Vall\'es and Schmidt, which used the Green's function Monte
Carlo method, we study the surface of liquid He within a slab geometry
using a larger number of particles in the slab and an updated interatomic
potential. The surface tension is accurately estimated from the energy of slabs
of increasing surface density and its value is close to one of the two existing
experimental values. Results for the density profiles allow for the calculation
of the surface width which shows an overall agreement with recent experimental
data. The dependence on the transverse direction to the surface of other
properties such as the two-body radial distribution function, structure factor,
and one-body density matrix is also studied. The condensate fraction, extracted
from the asymptotic behavior of the one-body density matrix, shows an
unambiguous enhancement when approaching the surface.Comment: RevTex, 11 pages, accepted in Phys. Rev.
Momentum distributions in ^3He-^4He liquid mixtures
We present variational calculations of the one-body density matrices and
momentum distributions for ^3He-^4He mixtures in the zero temperature limit, in
the framework of the correlated basis functions theory. The ground-state wave
function contains two- and three-body correlations and the matrix elements are
computed by (Fermi)Hypernetted Chain techniques. The dependence on the ^3He
concentration (x_3) of the ^4He condensate fraction and of the
^3He pole strength (Z_F) is studied along the P=0 isobar. At low ^3He
concentration, the computed ^4He condensate fraction is not significantly
affected by the ^3He statistics. Despite of the low x_3 values, Z_F is found to
be quite smaller than that of the corresponding pure ^3He because of the strong
^3He-^4He correlations and of the overall, large total density \rho. A small
increase of along x_3 is found, which is mainly due to the decrease
of \rho respect to the pure ^4He phase.Comment: 23 pages, 7 postscript figures, Revte
High-momentum dynamic structure function of liquid 3He-4He mixtures: a microscopic approach
The high-momentum dynamic structure function of liquid 3He-4He mixtures has
been studied introducing final state effects. Corrections to the impulse
approximation have been included using a generalized Gersch-Rodriguez theory
that properly takes into account the Fermi statistics of 3He atoms. The
microscopic inputs, as the momentum distributions and the two-body density
matrices, correspond to a variational (fermi)-hypernetted chain calculation.
The agreement with experimental data obtained at \AA is not
completely satisfactory, the comparison being difficult due to inconsistencies
present in the scattering measurements. The significant differences between the
experimental determinations of the 4He condensate fraction and the 3He kinetic
energy, and the theoretical results, still remain unsolved.Comment: 18 pages, 11 figures, to appear in Phys. Rev.
H2 in the interstitial channels of nanotube bundles
The equation of state of H2 adsorbed in the interstitial channels of a carbon
nanotube bundle has been calculated using the diffusion Monte Carlo method. The
possibility of a lattice dilation, induced by H2 adsorption, has been analyzed
by modeling the cohesion energy of the bundle. The influence of factors like
the interatomic potentials, the nanotube radius and the geometry of the channel
on the bundle swelling is systematically analyzed. The most critical input is
proved to be the C-H2 potential. Using the same model than in planar graphite,
which is expected to be also accurate in nanotubes, the dilation is observed to
be smaller than in previous estimations or even inexistent. H2 is highly
unidimensional near the equilibrium density, the radial degree of freedom
appearing progressively at higher densities.Comment: Accepted for publication in PR
An Institutional Framework for Heterogeneous Formal Development in UML
We present a framework for formal software development with UML. In contrast
to previous approaches that equip UML with a formal semantics, we follow an
institution based heterogeneous approach. This can express suitable formal
semantics of the different UML diagram types directly, without the need to map
everything to one specific formalism (let it be first-order logic or graph
grammars). We show how different aspects of the formal development process can
be coherently formalised, ranging from requirements over design and Hoare-style
conditions on code to the implementation itself. The framework can be used to
verify consistency of different UML diagrams both horizontally (e.g.,
consistency among various requirements) as well as vertically (e.g.,
correctness of design or implementation w.r.t. the requirements)
Mejora de las propiedades mecánicas y compatibilidad de mezclas de PHBV/PLA con plastificantes comerciales de origen bio
Actas del Congreso publicadas por ed. Compobell. ISBN 978-84-942655-8-7Mezclas de poli (3-hidroxibutirato-co-3-hidroxivalerato) (PHBV) y ácido poliláctico
(PLA) se prepararon con un plastificante comercial funcionalizado de origen bio. La
morfología obtenida, así como las propiedades mecánicas y dinamo-mecánicas de
probetas inyectadas se ha evaluado observándose una mejora en la compatibilidad del
PHBV y el PLA y un aumento en la deformación a rotura en tracción.A number of samples of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polylactic acid (PLA) were treated with a commercial funcionalised bio plasticiser. The relevant assessment was made on the morphology and both the mechanic and dynamo-mechanic properties obtained in the injected test tubes. An improvement in terms of compatibility between PHBV and PLA has been observed, as well as an increase in strain at break in tensile testing.Ministerio de Economía y Competitividad (proyecto MAT2012-38947-C02-01) y Pla de Promoció de la Investigació de la Universitat Jaume I (PREDOC / 2012/32
Validation of the Use of SEBS Blends as a Substitute for Liquid Silicone Rubber in Injection Processes
Liquid silicone rubber is an interesting material at an industrial level, but there are great difficulties in the design and machining of molds,
and in addition, it cannot be processed using conventional equipment. Therefore, new lines of research have focused on the search for new
materials capable of providing final properties similar to liquid silicone rubber, that can also be engineered using simple, conventional processes
and machinery. In this investigation, a range of compatible blends, based on two commercial grades of styrene-b-ethyleneco-
butylene-b-styrene (SEBS) thermoplastic elastomer, was studied in order to obtain a range of different Shore A hardness blends for
industrial applications where liquid silicone rubber (different hardness) is currently used. The two blended elastomers used had widely differing
Shore A hardness values (5 and 90). Once the blended materials had been characterized, the Cross and Williams et al. [20] (Cross-WLF)
mathematical model was applied in order to obtain theoretical performance curves for the viscosity of each of the blends. After this, a model
was developed using the Computer Aided Engineering (CAE) software package Autodesk Moldflow 2012TM. This computer modeling validated
the results obtained from the mathematical models, thus making available to process engineers the full range of hardnesses necessary
for industrial products (where liquid silicone rubber is used), while still providing the advantages of thermoplastic injection molding.The authors wish to thank "Ministerio de Ciencia e Innovacion" IPT-310000-2010-37 and Universidad Politecnica de Valencia PAID 10012 for their financial support.Juárez Varón, D.; R. Balart; T. Boronat; Reig Pérez, MJ.; Ferrándiz Bou, S. (2013). Validation of the Use of SEBS Blends as a Substitute for Liquid Silicone Rubber in Injection Processes. Materials and Manufacturing Processes. 28(11):1215-1221. doi:10.1080/10426914.2013.811732S121512212811Zhang, B., Wong, J. S.-P., Shi, D., Yam, R. C.-M., & Li, R. K.-Y. (2010). Investigation on the mechanical performances of ternary nylon 6/SEBS elastomer/nano-SiO2hybrid composites with controlled morphology. Journal of Applied Polymer Science, 115(1), 469-479. doi:10.1002/app.30185Su, F.-H., & Huang, H.-X. (2009). Mechanical and rheological properties of PP/SEBS/OMMT ternary composites. Journal of Applied Polymer Science, 112(5), 3016-3023. doi:10.1002/app.29875Sugimoto, M., Sakai, K., Aoki, Y., Taniguchi, T., Koyama, K., & Ueda, T. (2009). Rheology and morphology change with temperature of SEBS/hydrocarbon oil blends. Journal of Polymer Science Part B: Polymer Physics, 47(10), 955-965. doi:10.1002/polb.21699Jose, A. J., Alagar, M., & P. Thomas, S. (2012). Preparation and Characterization of Organoclay Filled Polysulfone Nanocomposites. Materials and Manufacturing Processes, 27(3), 247-254. doi:10.1080/10426914.2011.585490Ivanović, N., Marjanović, N., Grbović Novaković, J., Manasijević, M., Rakočević, Z., Andrić, V., & Hadžić, B. (2009). Experimental and Theoretical Investigations of Cured and Uncured Disiloxane Bisbenzocyclobutene Thin Films. Materials and Manufacturing Processes, 24(10-11), 1180-1184. doi:10.1080/10426910902978811Perisić, M., Radojević, V., Uskoković, P. S., Stojanović, D., Jokić, B., & Aleksić, R. (2009). Wood–Thermoplastic Composites Based on Industrial Waste and Virgin High-Density Polyethylene (HDPE). Materials and Manufacturing Processes, 24(10-11), 1207-1213. doi:10.1080/10426910903032212Iqbal, H., Sheikh, A. K., Al-Yousef, A., & Younas, M. (2012). Mold Design Optimization for Sand Casting of Complex Geometries Using Advance Simulation Tools. Materials and Manufacturing Processes, 27(7), 775-785. doi:10.1080/10426914.2011.648250Özek, C., & Çelık, Y. H. (2011). Calculating Molding Parameters in Plastic Injection Molds with ANN and Developing Software. Materials and Manufacturing Processes, 27(2), 160-168. doi:10.1080/10426914.2011.560224Hirschmanner, M., Mörwald, K., & Fröhlich, C. (2011). Next Generation Mold Level Control: Development of LevCon 2.0. Materials and Manufacturing Processes, 26(1), 169-174. doi:10.1080/10426910903206691Selvakumar, P., & Bhatnagar, N. (2009). Studies on Polypropylene/Carbon Fiber Composite Foams by Nozzle-Based Microcellular Injection Molding System. Materials and Manufacturing Processes, 24(5), 533-540. doi:10.1080/10426910902742738Gramegna, N., Corte, E. D., & Poles, S. (2011). Manufacturing Process Simulation for Product Design Chain Optimization. Materials and Manufacturing Processes, 26(3), 527-533. doi:10.1080/10426914.2011.564248Marković, G., Radovanović, B., Marinović-Cincović, M., & Budinski-Simendić, J. (2009). The Effect of Accelerators on Curing Characteristics and Properties of Natural Rubber/Chlorosulphonated Polyethylene Rubber Blend. Materials and Manufacturing Processes, 24(10-11), 1224-1228. doi:10.1080/10426910902967087Mehat, N. M., & Kamaruddin, S. (2011). Investigating the Effects of Injection Molding Parameters on the Mechanical Properties of Recycled Plastic Parts Using the Taguchi Method. Materials and Manufacturing Processes, 26(2), 202-209. doi:10.1080/10426914.2010.529587Chen, C.-C., Su, P.-L., Chiou, C.-B., & Chiang, K.-T. (2011). Experimental Investigation of Designed Parameters on Dimension Shrinkage of Injection Molded Thin-Wall Part by Integrated Response Surface Methodology and Genetic Algorithm: A Case Study. Materials and Manufacturing Processes, 26(3), 534-540. doi:10.1080/10426914.2010.530331Martinez, A., Castany, J., & Aisa, J. (2011). Characterization of In-Mold Decoration Process and Influence of the Fabric Characteristics in This Process. Materials and Manufacturing Processes, 26(9), 1164-1172. doi:10.1080/10426914.2010.536934Primo Benitez-Rangel, J., Trejo-Hernández, M., Alberto Morales-Hernández, L., & Domínguez-González, A. (2010). Improvement of the Injection Mold Process by Using Vibration Through a Mold Accessory. Materials and Manufacturing Processes, 25(7), 577-580. doi:10.1080/10426910903124902Chen, C.-C. (2011). Design of Effective Parameters on the Wick-Debinding Process for Powder Injection Molded Green Compact. Materials and Manufacturing Processes, 26(10), 1261-1268. doi:10.1080/10426914.2010.544826Boronat, T., Segui, V. J., Peydro, M. A., & Reig, M. J. (2009). Influence of temperature and shear rate on the rheology and processability of reprocessed ABS in injection molding process. Journal of Materials Processing Technology, 209(5), 2735-2745. doi:10.1016/j.jmatprotec.2008.06.013Cross, M. M. (1965). Rheology of non-Newtonian fluids: A new flow equation for pseudoplastic systems. Journal of Colloid Science, 20(5), 417-437. doi:10.1016/0095-8522(65)90022-xReig, M. J., Segui, V. J., & Zamanillo, J. D. (2005). Rheological Behavior Modeling of Recycled ABS/PC Blends Applied to Injection Molding Process. Journal of Polymer Engineering, 25(5). doi:10.1515/polyeng.2005.25.5.43
A precise characterisation of the top quark electro-weak vertices at the ILC
Top quark production in the process at a future linear
electron positron collider with polarised beams is a powerful tool to determine
indirectly the scale of new physics. The presented study, based on a detailed
simulation of the ILD detector concept, assumes a centre-of-mass energy of
GeV and a luminosity of
equally shared between the incoming beam polarisations of . Events are selected in which the top pair
decays semi-leptonically and the cross sections and the forward-backward
asymmetries are determined. Based on these results, the vector, axial vector
and tensorial conserving couplings are extracted separately for the photon
and the component. With the expected precision, a large number of models
in which the top quark acts as a messenger to new physics can be distinguished
with many standard deviations. This will dramatically improve expectations from
e.g. the LHC for electro-weak couplings of the top quark.Comment: This work is an update of arXiv:1307.8102, minor changes w.r.t. v1
(typos, wrong grammar, incomplete sentences etc.
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