Search results for "Simulation."

Interaction of Charged Amino-Acid Side Chains with Ions: An Optimization Strategy for Classical Force Fields

2014

Many well-established classical biomolecular force fields, fitted on the solvation properties of single ions, do not necessarily describe all the details of ion pairing accurately, especially for complex polyatomic ions. Depending on the target application, it might not be sufficient to reproduce the thermodynamics of ion pairing, but it may also be necessary to correctly capture structural details, such as the coordination mode. In this work, we analyzed how classical force fields can be optimized to yield a realistic description of these different aspects of ion pairing. Given the prominent role of the interactions of negatively charged amino-acid side chains and divalent cations in many …

Modelling and simulation of gas-liquid hydrodynamics in mechnically stirred tanks

2007

Abstract Computational fuid dynamics (CFD) is an increasingly important tool for carrying out realistic simulations of process equipment. In the case of multiphase systems the development of CFD models is less advanced than for single-phase systems. In the present work CFD simulations of gas–liquid stirred tanks are reported. An Eulerian–Eulerian multi-fluid approach is used in conjunction with the simplest two-phase extension of the k–ɛ turbulence model. All bubbles are assumed to share the same size. The effect of inter-phase forces on simulation results is separately considered. As concerns drag, it is shown that the sole parameter needed to characterize the dispersed phase behaviour is …

Numerical study of photolithography system: electromagnetic differential method

2004

The R-matrix propagation algorithm is incorporated into the differential method to achieve an extended capability for modelling a photolithography systems. We show throughout this work the ability of the R-matrix algorithm and differential method to analyse gratings of arbitrary depth, profile, and conductivity without encountering numerical instabilities. We calculate the field intensity and the transmitted amplitudes in the 0 and −1 orders below different masks. We study also the influence of the various parameters (incidence, groove spacing, groove depth and index of refraction) on the field intensity maps and the transmittivity power. These results agree with the experimental patent: we…

Interactive Visualization of DICOM Volumetric Datasets in the Web - Providing VR Experiences within the Web Browser

2017

Web Traffic Modeling for E-Commerce Web Server System

2009

The paper concerns a problem of the e-commerce Web server system performance evaluation through simulation experiments, especially a problem of modeling a representative stream of user requests at the input of such system. Motivated by a need of a benchmarking tool for the Business-to-Consumer (B2C) environment we discuss a workload model typical of such Web sites and also a model of a multi-tiered e-commerce Web server system. A simulation tool in which the proposed models have been implemented is briefly talked over and some experimental results on the Web system performance in terms of traditional and business performance measures are presented.

User-oriented evaluation of mechanical single-channel axial pipettes.

2013

Hand tools should be designed so that they are comfortable to use, fit the hand and are user-oriented. Six different manual, single-channel axial pipettes were evaluated for such objective outcomes as muscular activity, wrist postures and efficiency, as well as for subjective outcomes concerning self-assessed features of pipette usability and musculoskeletal strain. Ten experienced laboratory employees volunteered for the study. The results showed that light and short pipettes with better tool comfort resulted in reduced muscular activity and perceived musculoskeletal strain when they were compared with a long and heavy pipette. There were no differences in the efficiency between the differ…

Cyclic tetraureas with variable flexibility--synthesis, crystal structures and properties.

2008

Macrocyclic molecules containing several amide or urea functions may serve as anion receptors. We describe the synthesis of 32-membered macrocycles, in which four rigid xanthene units (X) and/or diphenyl ether units (D) as flexible analogues are linked via urea groups. All six possible combinations of these units (XXXX, XXXD, XXDD, XDXD, XDDD and DDDD) were synthesized and two examples were characterised by single-crystal X-ray analyses (DDDD and two structures for XXXD). Both macrocycles showed distinct differences in their overall conformation and consequently in their hydrogen-bonding pattern. Hydrogen-bonded solvent molecules are found for both compounds and intramolecular hydrogen bond…

IV-Curves of tunnel junction arrays at lowered temperature by numerical simulation

1996

We have numerically investigated the effect of lowered T on the performance of the Coulomb blockade thermometer, which has been demostrated to yield primary thermometry in the high T limit where thermal excitations compete with the Coulomb blockade. The thermometer is formed by an array of tunnel junctions whose differentiated IV—curve is used to determine the temperature. The IV—curves were calculated by computer simulations and we have obtained corrections to the analytic high T behaviour due to the lowered temperature.

"Table 1" of "Determination of $alpha_{s}$ in second order {QCD} from hadronic $Z$ decays"

1992

Experimental differential Thrust distributions.

Il metodo delle funzioni di trasferimento applicato ad un singola zona termica

2006

Nel lavoro viene presentato un algoritmo basato sull’utilizzo dell’operatore Z-Trasformata per lo studio della trasmissione del calore all’interno di una singola zona termica costituita da pareti multistrato. L’algoritmo utilizzato è molto versatile e potrebbe venire utilizzato per il calcolo dei coefficienti delle funzioni di trasferimento nella simulazione del comportamento termico di un ambiente in free floating. Noti i coefficienti delle funzioni di trasferimento è possibile simulare in regime dinamico il profilo della temperatura di ciascuna superficie interna e dell’aria interna all’ambiente analizzato. L’algoritmo viene descritto in maniera completa in tutte le sue parti. Per valutar…