Graduiertenschule Hybrid Monte Carlo
Heermann, Dieter W.
Graduiertenschule Hybrid Monte Carlo SS 2005 Heermann - Universit¨at Heidelberg Seite 1 #12;Graduiertenschule · In conventional Monte-Carlo (MC) calculations of condensed matter systems, such as an N probability distribution, unlike Monte-Carlo calculations. · The Hybrid Monte-Carlo (HMC) method combines
NASA Astrophysics Data System (ADS)
Miura, Shinichi
2007-03-01
In this paper, we present a path integral hybrid Monte Carlo (PIHMC) method for rotating molecules in quantum fluids. This is an extension of our PIHMC for correlated Bose fluids [S. Miura and J. Tanaka, J. Chem. Phys. 120, 2160 (2004)] to handle the molecular rotation quantum mechanically. A novel technique referred to be an effective potential of quantum rotation is introduced to incorporate the rotational degree of freedom in the path integral molecular dynamics or hybrid Monte Carlo algorithm. For a permutation move to satisfy Bose statistics, we devise a multilevel Metropolis method combined with a configurational-bias technique for efficiently sampling the permutation and the associated atomic coordinates. Then, we have applied the PIHMC to a helium-4 cluster doped with a carbonyl sulfide molecule. The effects of the quantum rotation on the solvation structure and energetics were examined. Translational and rotational fluctuations of the dopant in the superfluid cluster were also analyzed.
A Novel Multiple-Time Scale Integrator for the Hybrid Monte Carlo Algorithm
Kamleh, Waseem [Special Research Centre for the Subatomic Structure of Matter and Department of Physics, University of Adelaide 5005 (Australia)
2011-05-24
Hybrid Monte Carlo simulations that implement the fermion action using multiple terms are commonly used. By the nature of their formulation they involve multiple integration time scales in the evolution of the system through simulation time. These different scales are usually dealt with by the Sexton-Weingarten nested leapfrog integrator. In this scheme the choice of time scales is somewhat restricted as each time step must be an exact multiple of the next smallest scale in the sequence. A novel generalisation of the nested leapfrog integrator is introduced which allows for far greater flexibility in the choice of time scales, as each scale now must only be an exact multiple of the smallest step size.
NASA Astrophysics Data System (ADS)
Paquet, E.; Viktor, H. L.
2011-03-01
When considering probabilistic pattern recognition methods, especially methods based on Bayesian analysis, the probabilistic distribution is of the utmost importance. However, despite the fact that the geometry associated with the probability distribution constitutes essential background information, it is often not ascertained. This paper discusses how the standard Euclidian geometry should be generalized to the Riemannian geometry when a curvature is observed in the distribution. To this end, the probability distribution is defined for curved geometry. In order to calculate the probability distribution, a Lagrangian and a Hamiltonian constructed from curvature invariants are associated with the Riemannian geometry and a generalized hybrid Monte Carlo sampling is introduced. Finally, we consider the calculation of the probability distribution and the expectation in Riemannian space with path integrals, which allows a direct extension of the concept of probability to curved space.
NASA Astrophysics Data System (ADS)
Miura, Shinichi
2007-09-01
Microscopic structure of small helium-4 clusters doped with a carbonyl sulfide molecule, OCS(4He) N , at 0.37 K is studied by the path integral hybrid Monte Carlo method; the size of the cluster N ranges from N=2 to N=5. In all the cases examined in the present study, the helium atoms are localized around the carbon atom of the OCS molecule, forming a doughnut-type structure around the molecular axis. Bosonic exchange among the helium atoms is found to be promoted in the doughnut region, showing an anisotropic “superfluid” response of the clusters.
Extra Chance Hybrid Monte Carlo$ Cdric M. Campos
Sanz-Serna , J M
Extra Chance Hybrid Monte Carlo$ CÃ©dric M. Campos , J. M. Sanz-Serna Dept. MatemÃ¡tica Aplicada e Chance Generalized Hybrid Monte Carlo) to avoid rejections in the Hybrid Monte Carlo (HMC) method of the quality of the samples generated. Keywords: sampling methods, hybrid Monte Carlo, detailed balance
NASA Astrophysics Data System (ADS)
Suzuki, Kimichi; Tachikawa, Masanori; Shiga, Motoyuki
2010-04-01
We propose an efficient path integral hybrid Monte Carlo (PIHMC) method based on fourth-order Trotter expansion. Here, the second-order effective force is employed to generate short trial trajectories to avoid computationally expensive Hessian matrix, while the final acceptance is judged based on fourth-order effective potential. The computational performance of our PIHMC scheme is compared with that of conventional PIHMC and PIMD methods based on second- and fourth-order Trotter expansions. Our method is applied to on-the-fly ab initio PIHMC calculation of fluoride ion-water complexes, F-(H2O) and F-(D2O), at ambient temperature, particularly focusing on the geometrical isotope effect.
Hybrid Silicon Integration R. Jones et al. Hybrid Silicon Integration
Bowers, John
Hybrid Silicon Integration R. Jones et al. 1 / 23 Hybrid Silicon Integration R. Jones1 , H. D. Park.jones@intel.com #12;Hybrid Silicon Integration R. Jones et al. 2 / 23 Hybrid Silicon Integration R. Jones1 , H. D.jones@intel.com Abstract: An overview is presented of the hybrid AlGaInAs-silicon platform that enables wafer level
A separable shadow Hamiltonian hybrid Monte Carlo method.
Sweet, Christopher R; Hampton, Scott S; Skeel, Robert D; Izaguirre, Jesús A
2009-11-01
Hybrid Monte Carlo (HMC) is a rigorous sampling method that uses molecular dynamics (MD) as a global Monte Carlo move. The acceptance rate of HMC decays exponentially with system size. The shadow hybrid Monte Carlo (SHMC) was previously introduced to reduce this performance degradation by sampling instead from the shadow Hamiltonian defined for MD when using a symplectic integrator. SHMC's performance is limited by the need to generate momenta for the MD step from a nonseparable shadow Hamiltonian. We introduce the separable shadow Hamiltonian hybrid Monte Carlo (S2HMC) method based on a formulation of the leapfrog/Verlet integrator that corresponds to a separable shadow Hamiltonian, which allows efficient generation of momenta. S2HMC gives the acceptance rate of a fourth order integrator at the cost of a second-order integrator. Through numerical experiments we show that S2HMC consistently gives a speedup greater than two over HMC for systems with more than 4000 atoms for the same variance. By comparison, SHMC gave a maximum speedup of only 1.6 over HMC. S2HMC has the additional advantage of not requiring any user parameters beyond those of HMC. S2HMC is available in the program PROTOMOL 2.1. A Python version, adequate for didactic purposes, is also in MDL (http://mdlab.sourceforge.net/s2hmc). PMID:19894997
The Rational Hybrid Monte Carlo Algorithm
M. A. Clark
2006-10-06
The past few years have seen considerable progress in algorithmic development for the generation of gauge fields including the effects of dynamical fermions. The Rational Hybrid Monte Carlo (RHMC) algorithm, where Hybrid Monte Carlo is performed using a rational approximation in place the usual inverse quark matrix kernel is one of these developments. This algorithm has been found to be extremely beneficial in many areas of lattice QCD (chiral fermions, finite temperature, Wilson fermions etc.). We review the algorithm and some of these benefits, and we compare against other recent algorithm developements. We conclude with an update of the Berlin wall plot comparing costs of all popular fermion formulations.
TECHNICAL MATERIAL New Hybrid Monte Carlo Methods for Efficient Sampling
Reich, Sebastian
TECHNICAL MATERIAL New Hybrid Monte Carlo Methods for Efficient Sampling: from Physics to Biology in physics, biology, materials science and statistics. These generalized shadow Hybrid Monte Carlo (GSHMC known methods in sampling efficiency by an order of magnitude4) . KEYWORDS: Hybrid, Monte Carlo
TOWARDS A HYBRID MONTE CARLO METHOD FOR RAREFIED GAS DYNAMICS
Pareschi, Lorenzo
TOWARDS A HYBRID MONTE CARLO METHOD FOR RAREFIED GAS DYNAMICS RUSSEL E. CAFLISCH #3; AND LORENZO PARESCHI y Abstract. For the Boltzmann equation, we present a hybrid Monte Carlo method that is robust-equilibrium particle distribution and a Maxwellian. The hybrid distribution is then evolved by Monte Carlo
Non-Hermitian Polynomial Hybrid Monte Carlo
Oliver Witzel
2008-09-05
We report on a new variant of the hybrid Monte Carlo algorithm employing a polynomial approximation of the inverse of the non-Hermitian Dirac-Wilson operator. Our approximation relies on simple and stable recurrence relations of complex Chebyshev polynomials. First performance figures are presented.
Hybrid Radiosity\\/Monte Carlo Methods
Peter Shirley
1994-01-01
this document said that absorb and reemit wasasymptotically equivalent to the photon tracking model.8 Hybrid Radiosity\\/Monte Carlo MethodsRadiositySolutionGather fromsolution for smallarea zonesFinal (corrected)solutionFigure 4: Zones with small areas have their radiance recalculated more accurately in a postprocess.iteration (each ray carries approximately the same amount of power). The other is that, unlike in[7], the zone with the most power is not
Aklan, B; Jakoby, B W; Watson, C C; Braun, H; Ritt, P; Quick, H H
2015-06-21
A simulation toolkit, GATE (Geant4 Application for Tomographic Emission), was used to develop an accurate Monte Carlo (MC) simulation of a fully integrated 3T PET/MR hybrid imaging system (Siemens Biograph mMR). The PET/MR components of the Biograph mMR were simulated in order to allow a detailed study of variations of the system design on the PET performance, which are not easy to access and measure on a real PET/MR system. The 3T static magnetic field of the MR system was taken into account in all Monte Carlo simulations. The validation of the MC model was carried out against actual measurements performed on the PET/MR system by following the NEMA (National Electrical Manufacturers Association) NU 2-2007 standard. The comparison of simulated and experimental performance measurements included spatial resolution, sensitivity, scatter fraction, and count rate capability. The validated system model was then used for two different applications. The first application focused on investigating the effect of an extension of the PET field-of-view on the PET performance of the PET/MR system. The second application deals with simulating a modified system timing resolution and coincidence time window of the PET detector electronics in order to simulate time-of-flight (TOF) PET detection. A dedicated phantom was modeled to investigate the impact of TOF on overall PET image quality. Simulation results showed that the overall divergence between simulated and measured data was found to be less than 10%. Varying the detector geometry showed that the system sensitivity and noise equivalent count rate of the PET/MR system increased progressively with an increasing number of axial detector block rings, as to be expected. TOF-based PET reconstructions of the modeled phantom showed an improvement in signal-to-noise ratio and image contrast to the conventional non-TOF PET reconstructions. In conclusion, the validated MC simulation model of an integrated PET/MR system with an overall accuracy error of less than 10% can now be used for further MC simulation applications such as development of hardware components as well as for testing of new PET/MR software algorithms, such as assessment of point-spread function-based reconstruction algorithms. PMID:26040657
NASA Astrophysics Data System (ADS)
Aklan, B.; Jakoby, B. W.; Watson, C. C.; Braun, H.; Ritt, P.; Quick, H. H.
2015-06-01
A simulation toolkit, GATE (Geant4 Application for Tomographic Emission), was used to develop an accurate Monte Carlo (MC) simulation of a fully integrated 3T PET/MR hybrid imaging system (Siemens Biograph mMR). The PET/MR components of the Biograph mMR were simulated in order to allow a detailed study of variations of the system design on the PET performance, which are not easy to access and measure on a real PET/MR system. The 3T static magnetic field of the MR system was taken into account in all Monte Carlo simulations. The validation of the MC model was carried out against actual measurements performed on the PET/MR system by following the NEMA (National Electrical Manufacturers Association) NU 2-2007 standard. The comparison of simulated and experimental performance measurements included spatial resolution, sensitivity, scatter fraction, and count rate capability. The validated system model was then used for two different applications. The first application focused on investigating the effect of an extension of the PET field-of-view on the PET performance of the PET/MR system. The second application deals with simulating a modified system timing resolution and coincidence time window of the PET detector electronics in order to simulate time-of-flight (TOF) PET detection. A dedicated phantom was modeled to investigate the impact of TOF on overall PET image quality. Simulation results showed that the overall divergence between simulated and measured data was found to be less than 10%. Varying the detector geometry showed that the system sensitivity and noise equivalent count rate of the PET/MR system increased progressively with an increasing number of axial detector block rings, as to be expected. TOF-based PET reconstructions of the modeled phantom showed an improvement in signal-to-noise ratio and image contrast to the conventional non-TOF PET reconstructions. In conclusion, the validated MC simulation model of an integrated PET/MR system with an overall accuracy error of less than 10% can now be used for further MC simulation applications such as development of hardware components as well as for testing of new PET/MR software algorithms, such as assessment of point-spread function-based reconstruction algorithms.
Monte Carlo Integration Lecture 2 The Problem
Liang, Faming
Monte Carlo Integration Lecture 2 The Problem Let be a probability measure over the Borel -field X S and h(x) = 0 otherwise. #12;Monte Carlo Integration Lecture 2 When the problem appears to be intractable, Press et al (1992) and reference therein). For high dimensional problems, Monte Carlo methods have
Advanced topics 5.1 Hybrid Monte Carlo
Schofield, Jeremy
5 Advanced topics 5.1 Hybrid Monte Carlo 5.1.1 The Method One drawback of traditional Monte-Carlo in a Monte-Carlo procedure. See S. Duane, A.D. Kennedy, B.J. Pendleton and D. Roweth, Phys. Lett. B 45, 216;5.1. HYBRID MONTE CARLO 89 · Claim: The transition probability Eq. (5.3) satisfies the stationarity condition
Hybrid algorithms in quantum Monte Carlo
Esler, Kenneth P [ORNL] [ORNL; Mcminis, Jeremy [University of Illinois, Urbana-Champaign] [University of Illinois, Urbana-Champaign; Morales, Miguel A [Lawrence Livermore National Laboratory (LLNL)] [Lawrence Livermore National Laboratory (LLNL); Clark, Bryan K. [Princeton University] [Princeton University; Shulenburger, Luke [Sandia National Laboratory (SNL)] [Sandia National Laboratory (SNL); Ceperley, David M [ORNL] [ORNL
2012-01-01
With advances in algorithms and growing computing powers, quantum Monte Carlo (QMC) methods have become a leading contender for high accuracy calculations for the electronic structure of realistic systems. The performance gain on recent HPC systems is largely driven by increasing parallelism: the number of compute cores of a SMP and the number of SMPs have been going up, as the Top500 list attests. However, the available memory as well as the communication and memory bandwidth per element has not kept pace with the increasing parallelism. This severely limits the applicability of QMC and the problem size it can handle. OpenMP/MPI hybrid programming provides applications with simple but effective solutions to overcome efficiency and scalability bottlenecks on large-scale clusters based on multi/many-core SMPs. We discuss the design and implementation of hybrid methods in QMCPACK and analyze its performance on current HPC platforms characterized by various memory and communication hierarchies.
Configuration Path Integral Monte Carlo
NASA Astrophysics Data System (ADS)
Bonitz, Michael; Schoof, Tim; Groth, Simon; Filinov, Alexei; Hochstuhl, David
2011-10-01
A novel path integral Monte Carlo (PIMC) approach for correlated many-particle systems with arbitrary pair interaction in continuous space at low temperatures is presented. It is based on a representation of the N-particle density operator in a basis of (anti-)symmetrized N-particle states (``configurations'' of occupation numbers). The path integral is transformed into a sum over trajectories with the same topology and, finally, the limit of M to infinity, (M is the number of high-temperature factors), is analytically performed. This yields exact expressions for the thermodynamic quantities and allows to perform efficient simulations for fermions at low temperature and weak to moderate coupling. Our method is applicable to dense quantum plasmas in the regime of strong degeneracy where conventional PIMC, e.g., fails due to the fermion sign problem. This work is supported by the Deutsche Forschungsgemeinschaft.
The Tunneling Hybrid Monte-Carlo algorithm
Maarten Golterman; Yigal Shamir
2007-10-09
The hermitian Wilson kernel used in the construction of the domain-wall and overlap Dirac operators has exceptionally small eigenvalues that make it expensive to reach high-quality chiral symmetry for domain-wall fermions, or high precision in the case of the overlap operator. An efficient way of suppressing such eigenmodes consists of including a positive power of the determinant of the Wilson kernel in the Boltzmann weight, but doing this also suppresses tunneling between topological sectors. Here we propose a modification of the Hybrid Monte-Carlo algorithm which aims to restore tunneling between topological sectors by excluding the lowest eigenmodes of the Wilson kernel from the molecular-dynamics evolution, and correcting for this at the accept/reject step. We discuss the implications of this modification for the acceptance rate.
Stanford University
Chapter 2 Monte Carlo Integration This chapter gives an introduction to Monte Carlo integration useful in computer graphics. Good references on Monte Carlo methods include Kalos & Whitlock [1986 for Monte Carlo applications to neutron transport problems; Lewis & Miller [1984] is a good source
Monte-Carlo Integration Using Cryptographically Secure Pseudorandom Generator
Hiroshi Sugita
2002-01-01
The drastic reduction of randomness by random Weyl sampling enables us to use cryptographically secure pseudo-random generators\\u000a for Monte-Carlo integration as well as for parallel Monte-Carlo integration.
Densmore, Jeffery D., E-mail: jdd@lanl.gov [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States); Thompson, Kelly G., E-mail: kgt@lanl.gov [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States); Urbatsch, Todd J., E-mail: tmonster@lanl.gov [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States)
2012-08-15
Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations in optically thick media. In DDMC, particles take discrete steps between spatial cells according to a discretized diffusion equation. Each discrete step replaces many smaller Monte Carlo steps, thus improving the efficiency of the simulation. In this paper, we present an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold, as optical thickness is typically a decreasing function of frequency. Above this threshold we employ standard Monte Carlo, which results in a hybrid transport-diffusion scheme. With a set of frequency-dependent test problems, we confirm the accuracy and increased efficiency of our new DDMC method.
Testing trivializing maps in the Hybrid Monte Carlo algorithm
Georg P. Engel; Stefan Schaefer
2011-02-09
We test a recent proposal to use approximate trivializing maps in a field theory to speed up Hybrid Monte Carlo simulations. Simulating the CP^{N-1} model, we find a small improvement with the leading order transformation, which is however compensated by the additional computational overhead. The scaling of the algorithm towards the continuum is not changed. In particular, the effect of the topological modes on the autocorrelation times is studied.
Replica exchange with Smart Monte Carlo and Hybrid Monte Carlo in manifolds
NASA Astrophysics Data System (ADS)
Jenkins, R.; Curotto, E.; Mella, Massimo
2013-12-01
Several Smart Monte Carlo (SMC) and Hybrid Monte Carlo (HMC) simulations coupled with the Replica Exchange (RE) strategy are compared in multidimensional flat and curved manifolds characterized by extremely rugged potential energy surfaces, to quantify their convergence properties with respect to walk length and overall cost. We learn that the HMC coupled with a sampling enhancing method is much more efficient in manifolds mapped with unconventional coordinates than SMC. This is due to an inherent difficulty in conserving energy in curved spaces directly mapped, and the lack of such strict requirement for HMC.
Faller, Roland
Constant pressure hybrid Molecular DynamicsMonte Carlo simulations Roland Faller and Juan J. de August 2001; accepted 28 September 2001 New hybrid Molecular Dynamics-Monte Carlo methods are proposed-pressure Monte Carlo technique based on the reversible generalization of the weak-coupling barostat H. J. C
Path Integral Monte Carlo Methods for Fermions
NASA Astrophysics Data System (ADS)
Ethan, Ethan; Dubois, Jonathan; Ceperley, David
2014-03-01
In general, Quantum Monte Carlo methods suffer from a sign problem when simulating fermionic systems. This causes the efficiency of a simulation to decrease exponentially with the number of particles and inverse temperature. To circumvent this issue, a nodal constraint is often implemented, restricting the Monte Carlo procedure from sampling paths that cause the many-body density matrix to change sign. Unfortunately, this high-dimensional nodal surface is not a priori known unless the system is exactly solvable, resulting in uncontrolled errors. We will discuss two possible routes to extend the applicability of finite-temperatue path integral Monte Carlo. First we extend the regime where signful simulations are possible through a novel permutation sampling scheme. Afterwards, we discuss a method to variationally improve the nodal surface by minimizing a free energy during simulation. Applications of these methods will include both free and interacting electron gases, concluding with discussion concerning extension to inhomogeneous systems. Support from DOE DE-FG52-09NA29456, DE-AC52-07NA27344, LLNL LDRD 10- ERD-058, and the Lawrence Scholar program.
Parallel Monte Carlo Approach for Integration of the Rendering Equation
Dimov, Ivan
Parallel Monte Carlo Approach for Integration of the Rendering Equation Ivan T. Dimov1 , Anton A are the Monte Carlo methods for solving the rendering equation in order to create photorealistic images. In this work we consider the Monte Carlo solving of the render- ing equation in the context of the parallel
Monte Carlo Reliability Model for Microwave Monolithic Integrated Circuits
Rubloff, Gary W.
Monte Carlo Reliability Model for Microwave Monolithic Integrated Circuits Aris Christou Materials of the failure rate of each component due to interaction effects of the failed components. The Monte Carlo failure rates become nonconstant. The Monte Carlo technique is an appropriate methodology used to treat
Optimized Fermion Path Integral Monte Carlo
NASA Astrophysics Data System (ADS)
Khairallah, Saad; Draeger, Erik; Shumway, John
2011-03-01
We present the latest developments in a new path integral Monte Carlo method for continuum fermions. The new formalism uses the maximum entropy principle to map the approximated density matrix to an effective bosonic problem. Verification and performance results are presented for both free electrons and compressed hydrogen, showing accurate results with a substantial performance gain over reference slice fPIMC, particularly at lower temperatures where ergodicity issues can significantly impact sampling efficiency. The limiting approximations in the method are identified and discussed, and suggest the need for improved nodal models. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
A Primer in Monte Carlo Integration Using Mathcad
ERIC Educational Resources Information Center
Hoyer, Chad E.; Kegerreis, Jeb S.
2013-01-01
The essentials of Monte Carlo integration are presented for use in an upper-level physical chemistry setting. A Mathcad document that aids in the dissemination and utilization of this information is described and is available in the Supporting Information. A brief outline of Monte Carlo integration is given, along with ideas and pedagogy for…
Accelerating Staggered Fermion Dynamics with the Rational Hybrid Monte Carlo (RHMC) Algorithm
M. A. Clark; A. D. Kennedy
2007-10-18
Improved staggered fermion formulations are a popular choice for lattice QCD calculations. Historically, the algorithm used for such calculations has been the inexact R algorithm, which has systematic errors that only vanish as the square of the integration step-size. We describe how the exact Rational Hybrid Monte Carlo (RHMC) algorithm may be used in this context, and show that for parameters corresponding to current state-of-the-art computations it leads to a factor of approximately seven decrease in cost as well as having no step-size errors.
A hybrid Monte Carlo and response matrix Monte Carlo method in criticality calculation
Li, Z.; Wang, K. [Dept. of Engineering Physics, Tsinghua Univ., Beijing, 100084 (China)
2012-07-01
Full core calculations are very useful and important in reactor physics analysis, especially in computing the full core power distributions, optimizing the refueling strategies and analyzing the depletion of fuels. To reduce the computing time and accelerate the convergence, a method named Response Matrix Monte Carlo (RMMC) method based on analog Monte Carlo simulation was used to calculate the fixed source neutron transport problems in repeated structures. To make more accurate calculations, we put forward the RMMC method based on non-analog Monte Carlo simulation and investigate the way to use RMMC method in criticality calculations. Then a new hybrid RMMC and MC (RMMC+MC) method is put forward to solve the criticality problems with combined repeated and flexible geometries. This new RMMC+MC method, having the advantages of both MC method and RMMC method, can not only increase the efficiency of calculations, also simulate more complex geometries rather than repeated structures. Several 1-D numerical problems are constructed to test the new RMMC and RMMC+MC method. The results show that RMMC method and RMMC+MC method can efficiently reduce the computing time and variations in the calculations. Finally, the future research directions are mentioned and discussed at the end of this paper to make RMMC method and RMMC+MC method more powerful. (authors)
ITER Neutronics Modeling Using Hybrid Monte Carlo/Deterministic and CAD-Based Monte Carlo Methods
Ibrahim, A. [University of Wisconsin; Mosher, Scott W [ORNL; Evans, Thomas M [ORNL; Peplow, Douglas E. [ORNL; Sawan, M. [University of Wisconsin; Wilson, P. [University of Wisconsin; Wagner, John C [ORNL; Heltemes, Thad [University of Wisconsin, Madison
2011-01-01
The immense size and complex geometry of the ITER experimental fusion reactor require the development of special techniques that can accurately and efficiently perform neutronics simulations with minimal human effort. This paper shows the effect of the hybrid Monte Carlo (MC)/deterministic techniques - Consistent Adjoint Driven Importance Sampling (CADIS) and Forward-Weighted CADIS (FW-CADIS) - in enhancing the efficiency of the neutronics modeling of ITER and demonstrates the applicability of coupling these methods with computer-aided-design-based MC. Three quantities were calculated in this analysis: the total nuclear heating in the inboard leg of the toroidal field coils (TFCs), the prompt dose outside the biological shield, and the total neutron and gamma fluxes over a mesh tally covering the entire reactor. The use of FW-CADIS in estimating the nuclear heating in the inboard TFCs resulted in a factor of ~ 275 increase in the MC figure of merit (FOM) compared with analog MC and a factor of ~ 9 compared with the traditional methods of variance reduction. By providing a factor of ~ 21 000 increase in the MC FOM, the radiation dose calculation showed how the CADIS method can be effectively used in the simulation of problems that are practically impossible using analog MC. The total flux calculation demonstrated the ability of FW-CADIS to simultaneously enhance the MC statistical precision throughout the entire ITER geometry. Collectively, these calculations demonstrate the ability of the hybrid techniques to accurately model very challenging shielding problems in reasonable execution times.
Direct Lighting Calculation by Monte Carlo Integration
Peter Shirley Changyaw Wang
1991-01-01
The details of doing a Monte Carlo direct lighting calculation are presented. For directlighting from multiple luminaires, a method of sending one shadow ray per viewing ray ispresented, and it is argued that this is preferable for scenes with many luminaires. Someissues of the design of probability densities on unions of luminaire surfaces are discussed.1 IntroductionMany rendering algorithms separately calculate
Path Integral Quantum Monte Carlo Benchmarks for Molecules and Plasmas
NASA Astrophysics Data System (ADS)
Shumway, John
2013-03-01
Path integral quantum Monte Carlo is used to simulate hot dense plasmas and other systems where quantum and thermal fluctuations are important. The fixed node approximation--ubiquitous in ab initio ground state Quantum Monte Carlo--is more complicated at finite temperatures, with many unanswered questions. In this talk I discuss the current state of fermionic path integral quantum Monte Carlo, with an emphasis on molecular systems where good benchmark data exists. We look at two ways of formulating the fixed node constraint and strategies for constructing finite-temperature nodal surfaces. We compare different the free energies of different nodal choices by sampling an ensemble of nodal models within a Monte Carlo simulation. We also present data on imaginary-time correlation fluctuations, which can be surprisingly accurate for molecular vibrations and polarizabilty. Path integral quantum Monte Carlo is used to simulate hot dense plasmas and other systems where quantum and thermal fluctuations are important. The fixed node approximation--ubiquitous in ab initio ground state Quantum Monte Carlo--is more complicated at finite temperatures, with many unanswered questions. In this talk I discuss the current state of fermionic path integral quantum Monte Carlo, with an emphasis on molecular systems where good benchmark data exists. We look at two ways of formulating the fixed node constraint and strategies for constructing finite-temperature nodal surfaces. We compare different the free energies of different nodal choices by sampling an ensemble of nodal models within a Monte Carlo simulation. We also present data on imaginary-time correlation fluctuations, which can be surprisingly accurate for molecular vibrations and polarizabilty. Work supported by NSF OCI 1148502.
Del Moral , Pierre
Sequential Monte Carlo simulation for the estimation of small reachability probabilities for stochastic hybrid systems Jaroslav Krystul and Henk A.P. Blom Abstract-- The problem of estimating the probability that a system reaches a given set within some time horizon is considered. Standard Monte Carlo
Hybridizing Constraint Programming and Monte-Carlo Tree Search: Application to the
Paris-Sud XI, Université de
Hybridizing Constraint Programming and Monte-Carlo Tree Search: Application to the Job Shop problem the solution space using tree search-based heuristics. Monte-Carlo Tree-Search (MCTS), a tree-search based. This paper examines the tight combination of MCTS and CP on the job shop problem (JSP). The contribution
Wu, Zhigang
Quantum Monte Carlo calculations of the energy-level alignment at hybrid interfaces: Role of many-level alignment at hybrid interfaces, using quantum Monte Carlo calculations to include many-body effects cancellation on both sides of the interface.11,12 However, a hybrid structure composed of two distinct
Hybrid Monte Carlo-Deterministic Methods for Nuclear Reactor-Related Criticality Calculations
Edward W. Larson
2004-02-17
The overall goal of this project is to develop, implement, and test new Hybrid Monte Carlo-deterministic (or simply Hybrid) methods for the more efficient and more accurate calculation of nuclear engineering criticality problems. These new methods will make use of two (philosophically and practically) very different techniques - the Monte Carlo technique, and the deterministic technique - which have been developed completely independently during the past 50 years. The concept of this proposal is to merge these two approaches and develop fundamentally new computational techniques that enhance the strengths of the individual Monte Carlo and deterministic approaches, while minimizing their weaknesses.
An application of the UV-filtering preconditioner to the Polynomial Hybrid Monte Carlo algorithm
PACS-CS Collaboration; :; K-I. Ishikawa; S. Aoki; T. Ishikawa; N. Ishizuka; K. Kanaya; Y. Kuramashi; M. Okawa; Y. Taniguchi; A. Ukawa; T. Yoshie
2006-10-11
We apply the UV-filtering preconditioner, previously used to improve the Multi-Boson algorithm, to the Polynomial Hybrid Monte Carlo (UV-PHMC) algorithm. The performance test for the algorithm is given for the plaquette gauge action and the $O(a)$-improved Wilson action at $\\beta=5.2, c_{\\mathrm{sw}}=2.02, M_{\\pi}/M_{\\rho}\\sim 0.8$ and 0.7 on a $16^3\\times 48$ lattice. We find that the UV-filtering reduces the magnitude of the molecular dynamics force from the pseudo fermion by a factor 3 by tuning the UV-filter parameter. Combining with the multi-time scale molecular dynamics integrator we achieve a factor 2 improvement.
CWDM Transmitter Module Based on Hybrid Integration
Torsten Mitze; Martin Schnarrenberger; Lars Zimmermann; J. Bruns; F. Fidorra; K. Janiak; J. Kreissl; S. Fidorra; H. Heidrich; K. Petermann
2006-01-01
A simple concept for hybrid integration and packaging of III\\/V active devices in a multipurpose optical platform is introduced. The board could be used as a coarse wavelength-division multiplexing transmitter with four lasers or as a receiver with photodiodes, respectively. The assembly ensures ample heat dissipation, so the laser performance does not suffer after the packaging
Path integral Monte Carlo and the electron gas
NASA Astrophysics Data System (ADS)
Brown, Ethan W.
Path integral Monte Carlo is a proven method for accurately simulating quantum mechanical systems at finite-temperature. By stochastically sampling Feynman's path integral representation of the quantum many-body density matrix, path integral Monte Carlo includes non-perturbative effects like thermal fluctuations and particle correlations in a natural way. Over the past 30 years, path integral Monte Carlo has been successfully employed to study the low density electron gas, high-pressure hydrogen, and superfluid helium. For systems where the role of Fermi statistics is important, however, traditional path integral Monte Carlo simulations have an exponentially decreasing efficiency with decreased temperature and increased system size. In this thesis, we work towards improving this efficiency, both through approximate and exact methods, as specifically applied to the homogeneous electron gas. We begin with a brief overview of the current state of atomic simulations at finite-temperature before we delve into a pedagogical review of the path integral Monte Carlo method. We then spend some time discussing the one major issue preventing exact simulation of Fermi systems, the sign problem. Afterwards, we introduce a way to circumvent the sign problem in PIMC simulations through a fixed-node constraint. We then apply this method to the homogeneous electron gas at a large swatch of densities and temperatures in order to map out the warm-dense matter regime. The electron gas can be a representative model for a host of real systems, from simple medals to stellar interiors. However, its most common use is as input into density functional theory. To this end, we aim to build an accurate representation of the electron gas from the ground state to the classical limit and examine its use in finite-temperature density functional formulations. The latter half of this thesis focuses on possible routes beyond the fixed-node approximation. As a first step, we utilize the variational principle inherent in the path integral Monte Carlo method to optimize the nodal surface. By using a ansatz resembling a free particle density matrix, we make a unique connection between a nodal effective mass and the traditional effective mass of many-body quantum theory. We then propose and test several alternate nodal ansatzes and apply them to single atomic systems. Finally, we propose a method to tackle the sign problem head on, by leveraging the relatively simple structure of permutation space. Using this method, we find we can perform exact simulations this of the electron gas and 3He that were previously impossible.
Hydrogen molecule ion: Path-integral Monte Carlo approach
I. Kylänpää; M. Leino; T. T. Rantala
2007-01-01
The path-integral Monte Carlo approach is used to study the coupled quantum dynamics of the electron and nuclei in hydrogen molecule ion. The coupling effects are demonstrated by comparing differences in adiabatic Born-Oppenheimer and nonadiabatic simulations, and inspecting projections of the full three-body dynamics onto the adiabatic Born-Oppenheimer approximation. Coupling of the electron and nuclear quantum dynamics is clearly seen.
Path Integral Monte Carlo calculation of hydrogen Hugoniot
NASA Astrophysics Data System (ADS)
Khairallah, Saad; Shumway, John; Draeger, Erik
2010-03-01
We use restricted path integral Monte Carlo to calculate the compression of liquid Hydrogen/Deuterium between 50 and 600 GPa for a temperature ranging from 10,000 to 1 Million Kelvin. Different theories and experiments place the compression between 4 and 6. We attempt to tackle this inconsistency with a new fermion fixed node algorithm and careful finite size effect study. Our preliminary results place the compression at 4.3.
The S/sub N//Monte Carlo response matrix hybrid method
Filippone, W.L.; Alcouffe, R.E.
1987-01-01
A hybrid method has been developed to iteratively couple S/sub N/ and Monte Carlo regions of the same problem. This technique avoids many of the restrictions and limitations of previous attempts to do the coupling and results in a general and relatively efficient method. We demonstrate the method with some simple examples.
Hybrid manufacturing : integrating direct write and sterolithography.
Davis, Donald W.; Inamdar, Asim (University of Texas at El Paso, El Paso, TX); Lopes, Amit (University of Texas at El Paso, El Paso, TX); Chavez, Bart D.; Gallegos, Phillip L.; Palmer, Jeremy Andrew (University of Texas at El Paso, El Paso, TX); Wicker, Ryan B. (University of Texas at El Paso); Medina, Francisco (University of Texas at El Paso, El Paso, TX); Hennessey, Robert E. (University of Texas at El Paso, El Paso, TX)
2005-07-01
A commercial stereolithography (SL) machine was modified to integrate fluid dispensing or direct-write (DW) technology with SL in an integrated manufacturing environment for automated and efficient hybrid manufacturing of complex electrical devices, combining three-dimensional (3D) electrical circuitry with SL-manufactured parts. The modified SL system operates similarly to a commercially available machine, although build interrupts were used to stop and start the SL build while depositing fluid using the DW system. An additional linear encoder was attached to the SL platform z-stage and used to maintain accurate part registration during the SL and DW build processes. Individual STL files were required as part of the manufacturing process plan. The DW system employed a three-axis translation mechanism that was integrated with the commercial SL machine. Registration between the SL part, SL laser and the DW nozzle was maintained through the use of 0.025-inch diameter cylindrical reference holes manufactured in the part during SL. After depositing conductive ink using DW, the SL laser was commanded to trace the profile until the ink was cured. The current system allows for easy exchange between SL and DW in order to manufacture fully functional 3D electrical circuits and structures in a semi-automated environment. To demonstrate the manufacturing capabilities, the hybrid SL/DW setup was used to make a simple multi-layer SL part with embedded circuitry. This hybrid system is not intended to function as a commercial system, it is intended for experimental demonstration only. This hybrid SL/DW system has the potential for manufacturing fully functional electromechanical devices that are more compact, less expensive, and more reliable than their conventional predecessors, and work is ongoing in order to fully automate the current system.
Path-integral Monte Carlo method for Rényi entanglement entropies
NASA Astrophysics Data System (ADS)
Herdman, C. M.; Inglis, Stephen; Roy, P.-N.; Melko, R. G.; Del Maestro, A.
2014-07-01
We introduce a quantum Monte Carlo algorithm to measure the Rényi entanglement entropies in systems of interacting bosons in the continuum. This approach is based on a path-integral ground state method that can be applied to interacting itinerant bosons in any spatial dimension with direct relevance to experimental systems of quantum fluids. We demonstrate how it may be used to compute spatial mode entanglement, particle partitioned entanglement, and the entanglement of particles, providing insights into quantum correlations generated by fluctuations, indistinguishability, and interactions. We present proof-of-principle calculations and benchmark against an exactly soluble model of interacting bosons in one spatial dimension. As this algorithm retains the fundamental polynomial scaling of quantum Monte Carlo when applied to sign-problem-free models, future applications should allow for the study of entanglement entropy in large-scale many-body systems of interacting bosons.
Hydrogen molecule ion: Path integral Monte Carlo approach
I. Kylanpaa; M. Leino; T. T. Rantala
2008-01-01
Path integral Monte Carlo approach is used to study the coupled quantum dynamics of the electron\\u000d\\u000aand nuclei in hydrogen molecule ion. The coupling effects are demonstrated by comparing differences\\u000d\\u000ain adiabatic Born–Oppenheimer and non-adiabatic simulations, and inspecting projections of the\\u000d\\u000afull three-body dynamics onto adiabatic Born–Oppenheimer approximation.\\u000d\\u000aCoupling of electron and nuclear quantum dynamics is clearly seen. Nuclear pair
Ibrahim, Ahmad M [ORNL] [ORNL; Peplow, Douglas E. [ORNL] [ORNL; Peterson, Joshua L [ORNL] [ORNL; Grove, Robert E [ORNL] [ORNL
2013-01-01
The rigorous 2-step (R2S) method uses three-dimensional Monte Carlo transport simulations to calculate the shutdown dose rate (SDDR) in fusion reactors. Accurate full-scale R2S calculations are impractical in fusion reactors because they require calculating space- and energy-dependent neutron fluxes everywhere inside the reactor. The use of global Monte Carlo variance reduction techniques was suggested for accelerating the neutron transport calculation of the R2S method. The prohibitive computational costs of these approaches, which increase with the problem size and amount of shielding materials, inhibit their use in the accurate full-scale neutronics analyses of fusion reactors. This paper describes a novel hybrid Monte Carlo/deterministic technique that uses the Consistent Adjoint Driven Importance Sampling (CADIS) methodology but focuses on multi-step shielding calculations. The Multi-Step CADIS (MS-CADIS) method speeds up the Monte Carlo neutron calculation of the R2S method using an importance function that represents the importance of the neutrons to the final SDDR. Using a simplified example, preliminarily results showed that the use of MS-CADIS enhanced the efficiency of the neutron Monte Carlo simulation of an SDDR calculation by a factor of 550 compared to standard global variance reduction techniques, and that the increase over analog Monte Carlo is higher than 10,000.
Finite element model updating using the shadow hybrid Monte Carlo technique
NASA Astrophysics Data System (ADS)
Boulkaibet, I.; Mthembu, L.; Marwala, T.; Friswell, M. I.; Adhikari, S.
2015-02-01
Recent research in the field of finite element model updating (FEM) advocates the adoption of Bayesian analysis techniques to dealing with the uncertainties associated with these models. However, Bayesian formulations require the evaluation of the Posterior Distribution Function which may not be available in analytical form. This is the case in FEM updating. In such cases sampling methods can provide good approximations of the Posterior distribution when implemented in the Bayesian context. Markov Chain Monte Carlo (MCMC) algorithms are the most popular sampling tools used to sample probability distributions. However, the efficiency of these algorithms is affected by the complexity of the systems (the size of the parameter space). The Hybrid Monte Carlo (HMC) offers a very important MCMC approach to dealing with higher-dimensional complex problems. The HMC uses the molecular dynamics (MD) steps as the global Monte Carlo (MC) moves to reach areas of high probability where the gradient of the log-density of the Posterior acts as a guide during the search process. However, the acceptance rate of HMC is sensitive to the system size as well as the time step used to evaluate the MD trajectory. To overcome this limitation we propose the use of the Shadow Hybrid Monte Carlo (SHMC) algorithm. The SHMC algorithm is a modified version of the Hybrid Monte Carlo (HMC) and designed to improve sampling for large-system sizes and time steps. This is done by sampling from a modified Hamiltonian function instead of the normal Hamiltonian function. In this paper, the efficiency and accuracy of the SHMC method is tested on the updating of two real structures; an unsymmetrical H-shaped beam structure and a GARTEUR SM-AG19 structure and is compared to the application of the HMC algorithm on the same structures.
Somasundaram, E.; Palmer, T. S. [Department of Nuclear Engineering and Radiation Health Physics, Oregon State University, 116 Radiation Center, Corvallis, OR 97332-5902 (United States)
2013-07-01
In this paper, the work that has been done to implement variance reduction techniques in a three dimensional, multi group Monte Carlo code - Tortilla, that works within the frame work of the commercial deterministic code - Attila, is presented. This project is aimed to develop an integrated Hybrid code that seamlessly takes advantage of the deterministic and Monte Carlo methods for deep shielding radiation detection problems. Tortilla takes advantage of Attila's features for generating the geometric mesh, cross section library and source definitions. Tortilla can also read importance functions (like adjoint scalar flux) generated from deterministic calculations performed in Attila and use them to employ variance reduction schemes in the Monte Carlo simulation. The variance reduction techniques that are implemented in Tortilla are based on the CADIS (Consistent Adjoint Driven Importance Sampling) method and the LIFT (Local Importance Function Transform) method. These methods make use of the results from an adjoint deterministic calculation to bias the particle transport using techniques like source biasing, survival biasing, transport biasing and weight windows. The results obtained so far and the challenges faced in implementing the variance reduction techniques are reported here. (authors)
Irbäck, Anders
Hybrid Monte Carlo simulation of polymer chains A. It-b&k Department of Theoretical Physics) We develop the hybrid Monte Carlo method for simulations of single off-lattice polymer chains. We(ln N)-". 1. INTRODUCTION Monte Carlo methods is a well-established tool in the study of polymer models
When Are Quasi-Monte Carlo Algorithms Efficient for High Dimensional Integrals?
Ian H. Sloan; Henryk Wozniakowski
1998-01-01
Recently, quasi-Monte Carlo algorithms have been successfully used for multivariate integration of high dimensiond, and were significantly more efficient than Monte Carlo algorithms. The existing theory of the worst case error bounds of quasi-Monte Carlo algorithms does not explain this phenomenon. This paper presents a partial answer to why quasi-Monte Carlo algorithms can work well for arbitrarily larged. It is
Development of integrated controller for a compound hybrid excavator
Jaewoong Choi; Hakgu Kim; Seungjin Yu; Kyongsu Yi
2011-01-01
This paper presents an integrated control algorithm for a compound hybrid excavator. Both conventional hydraulic excavator\\u000a and compound hybrid excavator models are developed to compute fuel consumption. The excavator simulation models, which consist\\u000a of engine, pump and electric components have been validated with test data. To design the hybrid system’s integrated control\\u000a algorithm which determines the output power of two
Hydrogen molecule ion: Path-integral Monte Carlo approach
Kylaenpaeae, I.; Leino, M.; Rantala, T. T. [Institute of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere (Finland)
2007-11-15
The path-integral Monte Carlo approach is used to study the coupled quantum dynamics of the electron and nuclei in hydrogen molecule ion. The coupling effects are demonstrated by comparing differences in adiabatic Born-Oppenheimer and nonadiabatic simulations, and inspecting projections of the full three-body dynamics onto the adiabatic Born-Oppenheimer approximation. Coupling of the electron and nuclear quantum dynamics is clearly seen. The nuclear pair correlation function is found to broaden by 0.040a{sub 0}, and the average bond length is larger by 0.056a{sub 0}. Also, a nonadiabatic correction to the binding energy is found. The electronic distribution is affected less than the nuclear one upon inclusion of nonadiabatic effects.
Monte Carlo Simulations of Background Spectra in Integral Imager Detectors
NASA Technical Reports Server (NTRS)
Armstrong, T. W.; Colborn, B. L.; Dietz, K. L.; Ramsey, B. D.; Weisskopf, M. C.
1998-01-01
Predictions of the expected gamma-ray backgrounds in the ISGRI (CdTe) and PiCsIT (Csl) detectors on INTEGRAL due to cosmic-ray interactions and the diffuse gamma-ray background have been made using a coupled set of Monte Carlo radiation transport codes (HETC, FLUKA, EGS4, and MORSE) and a detailed, 3-D mass model of the spacecraft and detector assemblies. The simulations include both the prompt background component from induced hadronic and electromagnetic cascades and the delayed component due to emissions from induced radioactivity. Background spectra have been obtained with and without the use of active (BGO) shielding and charged particle rejection to evaluate the effectiveness of anticoincidence counting on background rejection.
Hydrogen molecule ion: Path-integral Monte Carlo approach
NASA Astrophysics Data System (ADS)
Kylänpää, I.; Leino, M.; Rantala, T. T.
2007-11-01
The path-integral Monte Carlo approach is used to study the coupled quantum dynamics of the electron and nuclei in hydrogen molecule ion. The coupling effects are demonstrated by comparing differences in adiabatic Born-Oppenheimer and nonadiabatic simulations, and inspecting projections of the full three-body dynamics onto the adiabatic Born-Oppenheimer approximation. Coupling of the electron and nuclear quantum dynamics is clearly seen. The nuclear pair correlation function is found to broaden by 0.040a0 , and the average bond length is larger by 0.056a0 . Also, a nonadiabatic correction to the binding energy is found. The electronic distribution is affected less than the nuclear one upon inclusion of nonadiabatic effects.
Hydrogen molecule ion: Path integral Monte Carlo approach
Kylänpää, I; Rantala, T T
2007-01-01
Path integral Monte Carlo approach is used to study the coupled quantum dynamics of the electron and nuclei in hydrogen molecule ion. The coupling effects are demonstrated by comparing differences in adiabatic Born--Oppenheimer and non-adiabatic simulations, and inspecting projections of the full three-body dynamics onto adiabatic Born--Oppenheimer approximation. Coupling of electron and nuclear quantum dynamics is clearly seen. Nuclear pair correlation function is found to broaden by 0.040 a_0 and average bond length is larger by 0.056 a_0. Also, non-adiabatic correction to the binding energy is found. Electronic distribution is affected less, and therefore, we could say that the adiabatic approximation is better for the electron than for the nuclei.
Lecture 15 Monte Carlo integration Weinan E1,2
Li, Tiejun
@pku.edu.cn No.1 Science Building, 1575 #12;Monte Carlo methods: basics Variance reduction methods An introduction to Markov chain Outline Monte Carlo methods: basics Variance reduction methods An introduction to Markov chain #12;Monte Carlo methods: basics Variance reduction methods An introduction to Markov chain
CAD-based Monte Carlo Program for Integrated Simulation of Nuclear System SuperMC
NASA Astrophysics Data System (ADS)
Wu, Yican; Song, Jing; Zheng, Huaqing; Sun, Guangyao; Hao, Lijuan; Long, Pengcheng; Hu, Liqin
2014-06-01
Monte Carlo (MC) method has distinct advantages to simulate complicated nuclear systems and is envisioned as routine method for nuclear design and analysis in the future. High fidelity simulation with MC method coupled with multi-physical phenomenon simulation has significant impact on safety, economy and sustainability of nuclear systems. However, great challenges to current MC methods and codes prevent its application in real engineering project. SuperMC is a CAD-based Monte Carlo program for integrated simulation of nuclear system developed by FDS Team, China, making use of hybrid MC-deterministic method and advanced computer technologies. The design aim, architecture and main methodology of SuperMC were presented in this paper. SuperMC2.1, the latest version for neutron, photon and coupled neutron and photon transport calculation, has been developed and validated by using a series of benchmarking cases such as the fusion reactor ITER model and the fast reactor BN-600 model. SuperMC is still in its evolution process toward a general and routine tool for nuclear system. Warning, no authors found for 2014snam.conf06023.
A Hybrid Monte Carlo-Deterministic Method for Global Binary Stochastic Medium Transport Problems
Keady, K P; Brantley, P
2010-03-04
Global deep-penetration transport problems are difficult to solve using traditional Monte Carlo techniques. In these problems, the scalar flux distribution is desired at all points in the spatial domain (global nature), and the scalar flux typically drops by several orders of magnitude across the problem (deep-penetration nature). As a result, few particle histories may reach certain regions of the domain, producing a relatively large variance in tallies in those regions. Implicit capture (also known as survival biasing or absorption suppression) can be used to increase the efficiency of the Monte Carlo transport algorithm to some degree. A hybrid Monte Carlo-deterministic technique has previously been developed by Cooper and Larsen to reduce variance in global problems by distributing particles more evenly throughout the spatial domain. This hybrid method uses an approximate deterministic estimate of the forward scalar flux distribution to automatically generate weight windows for the Monte Carlo transport simulation, avoiding the necessity for the code user to specify the weight window parameters. In a binary stochastic medium, the material properties at a given spatial location are known only statistically. The most common approach to solving particle transport problems involving binary stochastic media is to use the atomic mix (AM) approximation in which the transport problem is solved using ensemble-averaged material properties. The most ubiquitous deterministic model developed specifically for solving binary stochastic media transport problems is the Levermore-Pomraning (L-P) model. Zimmerman and Adams proposed a Monte Carlo algorithm (Algorithm A) that solves the Levermore-Pomraning equations and another Monte Carlo algorithm (Algorithm B) that is more accurate as a result of improved local material realization modeling. Recent benchmark studies have shown that Algorithm B is often significantly more accurate than Algorithm A (and therefore the L-P model) for deep penetration problems such as examined in this paper. In this research, we investigate the application of a variant of the hybrid Monte Carlo-deterministic method proposed by Cooper and Larsen to global deep penetration problems involving binary stochastic media. To our knowledge, hybrid Monte Carlo-deterministic methods have not previously been applied to problems involving a stochastic medium. We investigate two approaches for computing the approximate deterministic estimate of the forward scalar flux distribution used to automatically generate the weight windows. The first approach uses the atomic mix approximation to the binary stochastic medium transport problem and a low-order discrete ordinates angular approximation. The second approach uses the Levermore-Pomraning model for the binary stochastic medium transport problem and a low-order discrete ordinates angular approximation. In both cases, we use Monte Carlo Algorithm B with weight windows automatically generated from the approximate forward scalar flux distribution to obtain the solution of the transport problem.
Rational hybrid Monte Carlo algorithm for theories with unknown spectral bounds
Kogut, J. B.; Sinclair, D. K. [Department of Energy, Division of High Energy Physics, Washington, D.C. 20585 (United States) and Dept. of Physics-TQHN, Univ. of Maryland, 82 Regents Dr., College Park, Maryland 20742 (United States); HEP Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)
2006-12-01
The Rational Hybrid Monte Carlo (RHMC) algorithm extends the Hybrid Monte Carlo algorithm for lattice QCD simulations to situations involving fractional powers of the determinant of the quadratic Dirac operator. This avoids the updating increment (dt) dependence of observables which plagues the Hybrid Molecular-dynamics (HMD) method. The RHMC algorithm uses rational approximations to fractional powers of the quadratic Dirac operator. Such approximations are only available when positive upper and lower bounds to the operator's spectrum are known. We apply the RHMC algorithm to simulations of 2 theories for which a positive lower spectral bound is unknown: lattice QCD with staggered quarks at finite isospin chemical potential and lattice QCD with massless staggered quarks and chiral 4-fermion interactions ({chi}QCD). A choice of lower bound is made in each case, and the properties of the RHMC simulations these define are studied. Justification of our choices of lower bounds is made by comparing measurements with those from HMD simulations, and by comparing different choices of lower bounds.
Rational hybrid Monte Carlo algorithm for theories with unknown spectral bounds.
Sinclair, D. K.; Kogut, J. B.; High Energy Physics; Univ. of Maryland
2006-12-01
The Rational Hybrid Monte Carlo (RHMC) algorithm extends the Hybrid Monte Carlo algorithm for lattice QCD simulations to situations involving fractional powers of the determinant of the quadratic Dirac operator. This avoids the updating increment (dt) dependence of observables which plagues the Hybrid Molecular-dynamics (HMD) method. The RHMC algorithm uses rational approximations to fractional powers of the quadratic Dirac operator. Such approximations are only available when positive upper and lower bounds to the operator's spectrum are known. We apply the RHMC algorithm to simulations of 2 theories for which a positive lower spectral bound is unknown: lattice QCD with staggered quarks at finite isospin chemical potential and lattice QCD with massless staggered quarks and chiral 4-fermion interactions (chiQCD). A choice of lower bound is made in each case, and the properties of the RHMC simulations these define are studied. Justification of our choices of lower bounds is made by comparing measurements with those from HMD simulations, and by comparing different choices of lower bounds.
Empirical Analysis of Stochastic Volatility Model by Hybrid Monte Carlo Algorithm
NASA Astrophysics Data System (ADS)
Takaishi, Tetsuya
2013-04-01
The stochastic volatility model is one of volatility models which infer latent volatility of asset returns. The Bayesian inference of the stochastic volatility (SV) model is performed by the hybrid Monte Carlo (HMC) algorithm which is superior to other Markov Chain Monte Carlo methods in sampling volatility variables. We perform the HMC simulations of the SV model for two liquid stock returns traded on the Tokyo Stock Exchange and measure the volatilities of those stock returns. Then we calculate the accuracy of the volatility measurement using the realized volatility as a proxy of the true volatility and compare the SV model with the GARCH model which is one of other volatility models. Using the accuracy calculated with the realized volatility we find that empirically the SV model performs better than the GARCH model.
A hybrid (Monte Carlo/deterministic) approach for multi-dimensional radiation transport
Bal, Guillaume, E-mail: gb2030@columbia.edu [Department of Applied Physics and Applied Mathematics, Columbia University, 200 S.W. Mudd Building, 500 W. 120th Street, New York, NY 10027 (United States); Davis, Anthony B., E-mail: Anthony.B.Davis@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-237, Pasadena, CA 91109 (United States); Kavli Institute for Theoretical Physics, Kohn Hall, University of California, Santa Barbara, CA 93106-4030 (United States); Langmore, Ian, E-mail: ianlangmore@gmail.com [Department of Applied Physics and Applied Mathematics, Columbia University, 200 S.W. Mudd Building, 500 W. 120th Street, New York, NY 10027 (United States)
2011-08-20
Highlights: {yields} We introduce a variance reduction scheme for Monte Carlo (MC) transport. {yields} The primary application is atmospheric remote sensing. {yields} The technique first solves the adjoint problem using a deterministic solver. {yields} Next, the adjoint solution is used as an importance function for the MC solver. {yields} The adjoint problem is solved quickly since it ignores the volume. - Abstract: A novel hybrid Monte Carlo transport scheme is demonstrated in a scene with solar illumination, scattering and absorbing 2D atmosphere, a textured reflecting mountain, and a small detector located in the sky (mounted on a satellite or a airplane). It uses a deterministic approximation of an adjoint transport solution to reduce variance, computed quickly by ignoring atmospheric interactions. This allows significant variance and computational cost reductions when the atmospheric scattering and absorption coefficient are small. When combined with an atmospheric photon-redirection scheme, significant variance reduction (equivalently acceleration) is achieved in the presence of atmospheric interactions.
A Hybrid (Monte-Carlo/Deterministic) Approach for Multi-Dimensional Radiation Transport
Guillaume Bal; Anthony Davis; Ian Langmore
2011-05-07
A novel hybrid Monte Carlo transport scheme is demonstrated in a scene with solar illumination, scattering and absorbing 2D atmosphere, a textured reflecting mountain, and a small detector located in the sky (mounted on a satellite or a airplane). It uses a deterministic approximation of an adjoint transport solution to reduce variance, computed quickly by ignoring atmospheric interactions. This allows significant variance and computational cost reductions when the atmospheric scattering and absorption coefficient are small. When combined with an atmospheric photon-redirection scheme, significant variance reduction (equivalently acceleration) is achieved in the presence of atmospheric interactions.
Design of integrated hybrid silicon waveguide optical gyroscope
Bowers, John
Design of integrated hybrid silicon waveguide optical gyroscope Sudharsanan Srinivasan,* Renan a novel highly integrated optical gyroscope using low loss silicon nitride waveguides. By integrating the dependence of sensitivity on sensor area. ©2014 Optical Society of America OCIS codes: (060.2800) Gyroscopes
Thermal dissociation of dipositronium: Path-integral Monte Carlo approach
NASA Astrophysics Data System (ADS)
Kylänpää, Ilkka; Rantala, Tapio T.
2009-08-01
Path-integral Monte Carlo simulation of the dipositronium “molecule” Ps2 reveals its surprising thermal instability. Although, the binding energy is ˜0.4eV , due to the strong temperature dependence of its free-energy Ps2 dissociates, or does not form, above ˜1000K , except for high densities where a small fraction of molecules are in equilibrium with Ps atoms. This prediction is consistent with the recently reported first observation of stable Ps2 molecules by Cassidy and Mills, Jr., [Nature (London) 449, 195 (2007); Phys. Rev. Lett. 100, 013401 (2008)] at temperatures below 1000 K. The relatively sharp transition from molecular to atomic equilibrium, which we find, remains to be experimentally verified. To shed light on the origin of the large entropy factor in free-energy, we analyze the nature of interatomic interactions of these strongly correlated quantum particles. The conventional diatomic potential curve is given by the van der Waals interaction at large distances; but due to the correlations and high delocalization of constituent particles, the concept of potential curve becomes ambiguous at short atomic distances.
High order Chin actions in path integral Monte Carlo
NASA Astrophysics Data System (ADS)
Sakkos, K.; Casulleras, J.; Boronat, J.
2009-05-01
High order actions proposed by Chin have been used for the first time in path integral Monte Carlo simulations. Contrary to the Takahashi-Imada action, which is accurate to the fourth order only for the trace, the Chin action is fully fourth order, with the additional advantage that the leading fourth-order error coefficients are finely tunable. By optimizing two free parameters entering in the new action, we show that the time step error dependence achieved is best fitted with a sixth order law. The computational effort per bead is increased but the total number of beads is greatly reduced and the efficiency improvement with respect to the primitive approximation is approximately a factor of 10. The Chin action is tested in a one-dimensional harmonic oscillator, a H2 drop, and bulk liquid H4e. In all cases a sixth-order law is obtained with values of the number of beads that compare well with the pair action approximation in the stringent test of superfluid H4e.
Chenhong Huang; Zuoguo Wu; Robert D. Nevels
1994-01-01
The stationary phase Monte Carlo (SPMC) path integral method is applied to analyze electromagnetic wave propagation in transversely inhomogeneous media. A filter, which gives a stable result with respect to various Monte Carlo parameters and thus overcomes the difficulties previously associated with the multi-dimensional SPMC technique, is constructed to evaluate the propagation field. Numerical results are presented for a graded-index
Using hybrid implicit Monte Carlo diffusion to simulate gray radiation hydrodynamics
NASA Astrophysics Data System (ADS)
Cleveland, Mathew A.; Gentile, Nick
2015-06-01
This work describes how to couple a hybrid Implicit Monte Carlo Diffusion (HIMCD) method with a Lagrangian hydrodynamics code to evaluate the coupled radiation hydrodynamics equations. This HIMCD method dynamically applies Implicit Monte Carlo Diffusion (IMD) [1] to regions of a problem that are opaque and diffusive while applying standard Implicit Monte Carlo (IMC) [2] to regions where the diffusion approximation is invalid. We show that this method significantly improves the computational efficiency as compared to a standard IMC/Hydrodynamics solver, when optically thick diffusive material is present, while maintaining accuracy. Two test cases are used to demonstrate the accuracy and performance of HIMCD as compared to IMC and IMD. The first is the Lowrie semi-analytic diffusive shock [3]. The second is a simple test case where the source radiation streams through optically thin material and heats a thick diffusive region of material causing it to rapidly expand. We found that HIMCD proves to be accurate, robust, and computationally efficient for these test problems.
Hybrid Integrals over Slater-Type Atomic Orbitals
Ralph E. Christoffersen; Klaus Ruedenberg
1968-01-01
General formulas for the evaluation of two-center hybrid integrals over Slater-type orbitals of arbitrary integral quantum numbers (nlm) are developed. The development leads to a single numerical integration over quantities f(r) and F(r), which are required for several integrals, and require only small tables of auxiliary functions for their evaluation. Formulas that are appropriate for use on an electronic computer
Hybrid Monte Carlo/Deterministic Methods for Accelerating Active Interrogation Modeling
Peplow, Douglas E. [ORNL; Miller, Thomas Martin [ORNL; Patton, Bruce W [ORNL; Wagner, John C [ORNL
2013-01-01
The potential for smuggling special nuclear material (SNM) into the United States is a major concern to homeland security, so federal agencies are investigating a variety of preventive measures, including detection and interdiction of SNM during transport. One approach for SNM detection, called active interrogation, uses a radiation source, such as a beam of neutrons or photons, to scan cargo containers and detect the products of induced fissions. In realistic cargo transport scenarios, the process of inducing and detecting fissions in SNM is difficult due to the presence of various and potentially thick materials between the radiation source and the SNM, and the practical limitations on radiation source strength and detection capabilities. Therefore, computer simulations are being used, along with experimental measurements, in efforts to design effective active interrogation detection systems. The computer simulations mostly consist of simulating radiation transport from the source to the detector region(s). Although the Monte Carlo method is predominantly used for these simulations, difficulties persist related to calculating statistically meaningful detector responses in practical computing times, thereby limiting their usefulness for design and evaluation of practical active interrogation systems. In previous work, the benefits of hybrid methods that use the results of approximate deterministic transport calculations to accelerate high-fidelity Monte Carlo simulations have been demonstrated for source-detector type problems. In this work, the hybrid methods are applied and evaluated for three example active interrogation problems. Additionally, a new approach is presented that uses multiple goal-based importance functions depending on a particle s relevance to the ultimate goal of the simulation. Results from the examples demonstrate that the application of hybrid methods to active interrogation problems dramatically increases their calculational efficiency.
Local Coarse-Grained Approximation to Path Integral Monte Carlo Integration for Fermion Systems
NASA Astrophysics Data System (ADS)
Sun, Deyan
2010-03-01
An approximate treatment of exchange in finite-temperature path integral Monte Carlo simulations for fermions has been proposed. In this method, some of the fine details of density matrix due to permutations have been smoothed over or averaged out by using the coarse-grained approximation. The practical usefulness of the method is tested for interacting fermions in a three dimensional harmonic well. The results show that, the present method not only reduces the sign fluctuation of the density matrix, but also avoid the fermion system collapsing into boson system at low temperatures. The method is substantiated to be exact when applied to free particles.
Hybrid Online Education: Identifying Integration Models Using Adventure Learning
ERIC Educational Resources Information Center
Doering, Aaron; Veletsianos, George
2008-01-01
In this paper we sought to understand how teachers chose to integrate a hybrid online education program in their classrooms, how students responded to this choice, and how students' experiences were influenced by the integration model chosen by the teachers. Data collected via classroom observations, personal interviews, and focus groups suggest…
The Acceptance Probability of the Hybrid Monte Carlo Method in High-Dimensional Problems
NASA Astrophysics Data System (ADS)
Beskos, A.; Pillai, N. S.; Roberts, G. O.; Sanz-Serna, J. M.; Stuart, A. M.
2010-09-01
We investigate the properties of the Hybrid Monte-Carlo algorithm in high dimensions. In the simplified scenario of independent, identically distributed components, we prove that, to obtain an G(1) acceptance probability as the dimension d of the state space tends to ?, the Verlet/leap-frog step-size h should be scaled as h = ?×d-1/4. We also identify analytically the asymptotically optimal acceptance probability, which turns out to be 0.651 (with three decimal places); this is the choice that optimally balances the cost of generating a proposal, which decreases as ? increases, against the cost related to the average number of proposals required to obtain acceptance, which increases as ? increases.
Global Evaluation of Prompt Dose Rates in ITER Using Hybrid Monte Carlo/Deterministic Techniques
Ibrahim, A. [University of Wisconsin; Sawan, M. [University of Wisconsin; Mosher, Scott W [ORNL; Evans, Thomas M [ORNL; Peplow, Douglas E. [ORNL; Wilson, P. [University of Wisconsin; Wagner, John C [ORNL
2011-01-01
The hybrid Monte Carlo (MC)/deterministic techniques - Consistent Adjoint Driven Importance Sampling (CADIS) and Forward Weighted CADIS (FW-CADIS) - enable the full 3-D modeling of very large and complicated geometries. The ability of performing global MC calculations for nuclear parameters throughout the entire ITER reactor was demonstrated. The 2 m biological shield (bioshield) reduces the total prompt operational dose by six orders of magnitude. The divertor cryo-pump port results in a peaking factor of 120 in the prompt operational dose rate behind the bioshield by a factor of 47. The peak values of the prompt dose rates at the back surface of the bioshield were 240 uSv/hr and 94 uSv/hr corresponding to the regions behind the divertor cryo-pump port and the equatorial port, respectively.
A hybrid Monte Carlo approach to the entanglement entropy of interacting fermions
Drut, Joaquín E
2015-01-01
The Monte Carlo calculation of R\\'enyi entanglement entropies $S^{}_n$ of interacting fermions suffers from a well-known signal-to-noise problem, even for a large number of situations in which the infamous sign problem is absent. A few methods have been proposed to overcome this issue, such as ensemble switching and the use of auxiliary partition-function ratios. Here, we present an approach that builds on the recently proposed free-fermion decomposition method; it incorporates entanglement in the probability measure in a natural way; it takes advantage of the hybrid Monte Carlo algorithm (an essential tool in lattice quantum chromodynamics and other gauge theories with dynamical fermions); and it does not suffer from noise problems. This method displays no sign problem for the same cases as other approaches and is therefore useful for a wide variety of systems. As a proof of principle, we calculate $S_2^{}$ for the one-dimensional, half-filled Hubbard model and compare with results from exact diagonalization...
Numerical Integration of the Langevin Equation: Monte Carlo Simulation
Donald L. Ermak; Helen Buckholz
1980-01-01
Monte Carlo simulation techniques are derived for solving the ordinary Langevin equation of motion for a Brownian particle in the presence of an external force. These methods allow considerable freedom in selecting the size of the time step, which is restricted only by the rate of change in the external force. This approach is extended to the generalized Langevin equation
Feasibility of a Monte Carlo-deterministic hybrid method for fast reactor analysis
Heo, W.; Kim, W.; Kim, Y. [Korea Advanced Institute of Science and Technology - KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); Yun, S. [Korea Atomic Energy Research Institute - KAERI, 989-111 Daedeok-daero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)
2013-07-01
A Monte Carlo and deterministic hybrid method is investigated for the analysis of fast reactors in this paper. Effective multi-group cross sections data are generated using a collision estimator in the MCNP5. A high order Legendre scattering cross section data generation module was added into the MCNP5 code. Both cross section data generated from MCNP5 and TRANSX/TWODANT using the homogeneous core model were compared, and were applied to DIF3D code for fast reactor core analysis of a 300 MWe SFR TRU burner core. For this analysis, 9 groups macroscopic-wise data was used. In this paper, a hybrid calculation MCNP5/DIF3D was used to analyze the core model. The cross section data was generated using MCNP5. The k{sub eff} and core power distribution were calculated using the 54 triangle FDM code DIF3D. A whole core calculation of the heterogeneous core model using the MCNP5 was selected as a reference. In terms of the k{sub eff}, 9-group MCNP5/DIF3D has a discrepancy of -154 pcm from the reference solution, 9-group TRANSX/TWODANT/DIF3D analysis gives -1070 pcm discrepancy. (authors)
Hybrid integration of light emitting diodes with photonic integrated circuits on silicon
D. Cristea; M. Modreanu; M. Caldararu; H. Cernica; V. Avramescu
1998-01-01
This paper presents the experiments we performed for hybrid integration of LEDs with silicon photonic integration circuits. LEDs were face down mounted in a silicon cavity. The edge-emitted light is coupled in SiON waveguides. The silicon cavity was obtained by anisotropic etching of the silicon substrate. The integration of all the components on one chip increases the sensor reliability and
Novel technology for hybrid integration of photonic and electronic circuits
Shinji Matsuo; Tatsushi Nakahara; Kouta Tateno; Takaslii Kurokawa
1996-01-01
We have developed a new three-dimensional integration technology which involves hybrid integration of photonic and electronic circuits by means of polyimide bonding. To demonstrate this technology, we fabricated a GaAs metal-semiconductor-metal photodetector on a silicon substrate. Each photodetector on a polyimide layer is electrically connected to the electrode on the silicon substrate. The electrical interconnection between the photodetector and electrode
NASA Astrophysics Data System (ADS)
Park, Sungjin; Shin, Hyeondeok; Kwon, Yongkyung
2012-08-01
The recently-proposed fourth-order propagator based on the multi-product expansion has been applied to path-integral Monte Carlo calculations for asymmetric quantum quadruploar rotors fixed at face-centered cubic lattice sites. The rotors are observed to undergo an orientational orderdisorder phase transition at a low temperature when the electric quadrupole-quadrupole interaction is strong enough. At intermediate interaction strength, a further decrease of temperature after the first transition to the ordered phase results in a reentrant transition back to the disordered phase. The theoretical phase diagram of these asymmetric rotors determined by using fourth-order path-integral Monte Carlo calculations is found to be in good quantitative agreement with the experimental one for solid hydrogen deuteride. This leads us to conclude that the fourth-order propagator can be effectively implemented for an accurate path-integral Monte Carlo calculation of a quantum many-body system with rotational degrees of freedom.
Path Integral Monte Carlo Simulation of Charged Particles in Traps
NASA Astrophysics Data System (ADS)
Filinov, Alexei; Böning, Jens; Bonitz, Michael
This chapter is devoted to the computation of equilibrium (thermodynamic) properties of quantum systems. In particular, we will be interested in the situation where the interaction between particles is so strong that it cannot be treated as a small perturbation. For weakly coupled systems many efficient theoretical and computational techniques do exist. However, for strongly interacting systems such as nonideal gases or plasmas, strongly correlated electrons and so on, perturbation methods fail and alternative approaches are needed. Among them, an extremely successful one is the Monte Carlo (MC) method which we are going to consider in this chapter.
High-order path-integral Monte Carlo methods for solving quantum dot problems.
Chin, Siu A
2015-03-01
The conventional second-order path-integral Monte Carlo method is plagued with the sign problem in solving many-fermion systems. This is due to the large number of antisymmetric free-fermion propagators that are needed to extract the ground state wave function at large imaginary time. In this work we show that optimized fourth-order path-integral Monte Carlo methods, which use no more than five free-fermion propagators, can yield accurate quantum dot energies for up to 20 polarized electrons with the use of the Hamiltonian energy estimator. PMID:25871047
Nasif, Hesham; Neyama, Atsushi
2003-02-26
This paper presents results of an uncertainty and sensitivity analysis for performance of the different barriers of high level radioactive waste repositories. SUA is a tool to perform the uncertainty and sensitivity on the output of Wavelet Integrated Repository System model (WIRS), which is developed to solve a system of nonlinear partial differential equations arising from the model formulation of radionuclide transport through repository. SUA performs sensitivity analysis (SA) and uncertainty analysis (UA) on a sample output from Monte Carlo simulation. The sample is generated by WIRS and contains the values of the output values of the maximum release rate in the form of time series and values of the input variables for a set of different simulations (runs), which are realized by varying the model input parameters. The Monte Carlo sample is generated with SUA as a pure random sample or using Latin Hypercube sampling technique. Tchebycheff and Kolmogrov confidence bounds are compute d on the maximum release rate for UA and effective non-parametric statistics to rank the influence of the model input parameters SA. Based on the results, we point out parameters that have primary influences on the performance of the engineered barrier system of a repository. The parameters found to be key contributor to the release rate are selenium and Cesium distribution coefficients in both geosphere and major water conducting fault (MWCF), the diffusion depth and water flow rate in the excavation-disturbed zone (EDZ).
New model for dwelling dose calculation using Monte Carlo integration.
Allam, K A
2009-02-01
A new methodology and computer model using Monte Carlo simulation for indoor dose calculation are developed. A room model of six rectangular slabs of finite thickness with door or window in each slab was used. Point-kernel photon transport model with self-absorption correction was applied for dose calculations. New software was designed and programmed using Pascal programming language, which was evaluated for standard room design. The calculated dose due to natural radionuclides in the concert walls has differences from the average model results of 0.21% for (238)U, 12.3% for (232)Th and 13.9% for (40)K; and the variability of specific dose rate with changing position density and composition of walls was studied. The new model has more flexibility for real dose calculation of any room structure and tailing, which is not given in the published models. PMID:19287012
Bousige, Colin; Bo?an, Alexandru; Ulm, Franz-Josef; Pellenq, Roland J-M; Coasne, Benoît
2015-03-21
We report an efficient atom-scale reconstruction method that consists of combining the Hybrid Reverse Monte Carlo algorithm (HRMC) with Molecular Dynamics (MD) in the framework of a simulated annealing technique. In the spirit of the experimentally constrained molecular relaxation technique [Biswas et al., Phys. Rev. B 69, 195207 (2004)], this modified procedure offers a refined strategy in the field of reconstruction techniques, with special interest for heterogeneous and disordered solids such as amorphous porous materials. While the HRMC method generates physical structures, thanks to the use of energy penalties, the combination with MD makes the method at least one order of magnitude faster than HRMC simulations to obtain structures of similar quality. Furthermore, in order to ensure the transferability of this technique, we provide rational arguments to select the various input parameters such as the relative weight ? of the energy penalty with respect to the structure optimization. By applying the method to disordered porous carbons, we show that adsorption properties provide data to test the global texture of the reconstructed sample but are only weakly sensitive to the presence of defects. In contrast, the vibrational properties such as the phonon density of states are found to be very sensitive to the local structure of the sample. PMID:25796236
Molecular dynamics and Monte Carlo hybrid simulation for fuzzy tungsten nanostructure formation
NASA Astrophysics Data System (ADS)
Ito, A. M.; Takayama, A.; Oda, Y.; Tamura, T.; Kobayashi, R.; Hattori, T.; Ogata, S.; Ohno, N.; Kajita, S.; Yajima, M.; Noiri, Y.; Yoshimoto, Y.; Saito, S.; Takamura, S.; Murashima, T.; Miyamoto, M.; Nakamura, H.
2015-07-01
For the purposes of long-term use of tungsten divertor walls, the formation process of the fuzzy tungsten nanostructure induced by exposure to the helium plasma was studied. In the present paper, the fuzzy nanostructure's formation has been successfully reproduced by the new hybrid simulation method in which the deformation of the tungsten material due to pressure of the helium bubbles was simulated by the molecular dynamics and the diffusion of the helium atoms was simulated by the random walk based on the Monte Carlo method. By the simulation results, the surface height of the fuzzy nanostructure increased only when helium retention was under the steady state. It was proven that the growth of the fuzzy nanostructure was brought about by bursting of the helium bubbles. Moreover, we suggest the following key formation mechanisms of the fuzzy nanostructure: (1) lifting in which the surface lifted up by the helium bubble changes into a convexity, (2) bursting by which the region of the helium bubble changes into a concavity, and (3) the difference of the probability of helium retention by which the helium bubbles tend to appear under the concavity. Consequently, the convex-concave surface structure was enhanced and grew to create the fuzzy nanostructure.
Comparison of hybrid and pure Monte Carlo shower generators on an event by event basis
Jeff Allen; Hans-Joachim Drescher; Glennys Farrar
2007-08-21
SENECA is a hybrid air shower simulation written by H. Drescher that utilizes both Monte Carlo simulation and cascade equations. By using the cascade equations only in the high energy portion of the shower, where the shower is inherently one-dimensional, SENECA is able to utilize the advantages in speed from the cascade equations yet still produce complete, three dimensional particle distributions at ground level which capture the shower to shower variations coming from the early interactions. We present a comparison, on an event by event basis, of SENECA and CORSIKA, a well trusted MC simulation code. By using the same first interaction in both SENECA and CORSIKA, the effect of the cascade equations can be studied within a single shower, rather than averaged over many showers. Our study shows that for showers produced in this manner, SENECA agrees with CORSIKA to a very high accuracy with respect to densities, energies, and timing information for individual species of ground-level particles from both iron and proton primaries with energies between 1 EeV and 100 EeV. Used properly, SENECA produces ground particle distributions virtually indistinguishable from those of CORSIKA in a fraction of the time. For example, for a shower induced by a 10 EeV proton, SENECA is 10 times faster than CORSIKA, with comparable accuracy.
Abdel-Khalik, Hany S.; Gardner, Robin; Mattingly, John; Sood, Avneet
2014-05-20
The development of hybrid Monte-Carlo-Deterministic (MC-DT) approaches, taking place over the past few decades, have primarily focused on shielding and detection applications where the analysis requires a small number of responses, i.e. at the detector locations(s). This work further develops a recently introduced global variance reduction approach, denoted by the SUBSPACE approach is designed to allow the use of MC simulation, currently limited to benchmarking calculations, for routine engineering calulations. By way of demonstration, the SUBSPACE approach is applied to assembly level calculations used to generate the few-group homogenized cross-sections. These models are typically expensive and need to be executed in the order of 10-10 times to properly characterize the few-group cross-sections for deownstream core-wide calculations. Applicability to k-eigenvalue core-wide models is also demonstrated in this work. Given the faborable results obtained in this work, we believe the applicability of the MC method for reactor analysis calculations could be realized in the near future.
Neutral depletion in inductively coupled plasmas using hybrid-type direct simulation Monte Carlo
Shimada, Masashi; Tynan, George R.; Cattolica, Robert [Department of Mechanical and Aerospace Engineering, and Center for Energy Research, University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States)
2008-02-01
Neutral and ion transport phenomena were simulated by a hybrid-type direct simulation Monte Carlo (DSMC) method for a one-dimensional (1D) electrostatic plasma in Ar/N{sub 2} mixtures to identify the mechanism of neutral depletion. The results show that gas heating and pressure balance are the main mechanisms of neutral depletion in an inductively coupled plasma. When plasma pressure becomes comparable to neutral pressure in high density plasma sources (T{sub e}{approx}2-5 eV, n{sub e}{approx}10{sup 11}-10{sup 12} cm{sup -3}), the total pressure (neutral pressure and plasma pressure) is conserved. Therefore, the finite plasma pressure (mainly electron pressure) reduces the neutral pressure. Neutrals collide with ions that have been accelerated by the ambipolar electric field and with Franck-Condon dissociated atoms, resulting in gas heating. Significant neutral depletion (up to 90%) is found at the typical condition of inductively coupled plasma process reactors. The resulting neutral depletion enhances the plasma transport to the surrounding wall, increases the particle loss, and decreases the plasma density.
Path-integral quantum Monte Carlo studies of lattice polarons and bipolarons
NASA Astrophysics Data System (ADS)
Kornilovitch, Pavel
2008-05-01
A path-integral Quantum Monte Carlo method for lattice polaron and bipolaron is presented. Analytical integration eliminates the phonons exactly leading to one or two self-interacting imaginary-time trajectories, which are then simulated by Metropolis Monte Carlo. Projection operators separate states of different symmetry, which provides access to various excited states such as the polaron energy, spectrum, effective mass, density of states and singlet-triplet bipolaron splitting. Monte Carlo updates are formulated in continuous imaginary time on infinite lattices and as such provide statistically unbiased results without finite-size and finite time-step errors. Numerical data are presented for models with short-range and long-range electron--phonon interactions. It is shown that a long-range electron-phonon interaction dramatically reduces the polaron and bipolaron mass, potentially leading to a high critical temperature of the bipolaronic superconductor.
Integrated Hybrid System Architecture for Risk Analysis
NASA Technical Reports Server (NTRS)
Moynihan, Gary P.; Fonseca, Daniel J.; Ray, Paul S.
2010-01-01
A conceptual design has been announced of an expert-system computer program, and the development of a prototype of the program, intended for use as a project-management tool. The program integrates schedule and risk data for the purpose of determining the schedule applications of safety risks and, somewhat conversely, the effects of changes in schedules on changes on safety. It is noted that the design has been delivered to a NASA client and that it is planned to disclose the design in a conference presentation.
DNA amplification and hybridization assays in integrated plastic monolithic devices.
Liu, Yingjie; Rauch, Cory B; Stevens, Randall L; Lenigk, Ralf; Yang, Jianing; Rhine, David B; Grodzinski, Piotr
2002-07-01
PCR amplification, DNA hybridization, and a hybridization wash have been integrated in a disposable monolithic DNA device, containing all of the necessary fluidic channels and reservoirs. These integrated devices were fabricated in polycarbonate plastic material by CO2 laser machining and were assembled using a combination of thermal bonding and adhesive tape bonding. Pluronics polymer phase change valves were implemented in the devices to fulfill the valving requirements. Pluronics polymer material is PCR compatible, and 30% Pluronics polymer valves provide enough holding pressure to ensure a successful PCR amplification. By reducing the temperature locally, to approximately 5 degrees C, Pluronics valves were liquefied and easily opened. A hybridization channel was made functional by oligonucleotide deposition, using Motorola proprietary surface attachment chemistry. Reagent transport on the device was provided by syringe pumps, which were docked onto the device. Peltier thermal electrical devices powered the heating and cooling functionality of the device. Asymmetrical PCR amplification and subsequent hybridization detection of both Escherichia coli K-12 MG1655 and Enterococcus faecalis DNAE genes have been successfully demonstrated in these disposable monolithic devices. PMID:12141665
Stevens, Bjorn
Monte Carlo spectra integration: A consistent approximation for radiative transfer in large eddy-dynamical simulation. Current methods for detailed radiation calculations, even those using simple one is acceptable in radiative transfer treatments for large eddy simulation? The term "large-eddy simulation" (LES
Improvements to the Integrated TIGER Series Monte Carlo radiation transport codes
L. Montgomery Smith; Reuben D. Hochstedler
1997-01-01
This paper describes two areas in which the usability of the Integrated TIGER Series (ITS) Monte Carlo radiation transport codes has been improved for use in the design and analysis of tests conducted with the DECADE nuclear weapons effects simulator. The first area is in improving the speed of execution. By benchmarking and profiling the member codes of the ITS
Atsushi Mori; Brian B. Laird; Yoshihiro Kangawa; Tomonori Ito; Akinori Koukitu
2003-01-01
Formulation is given for the Gibbs-Duhem integration (GDI) method in the semigrand canonical (SGC) ensemble, in which the total number of particles N is fixed with the specified chemical potential differences between species ?? i (?? i -?? 1 ;i =2,3,...). Demonstration of the SGC Monte Carlo simulation with the GDI technique is given for a pseudo-binary semiconductor alloy, In
Color path-integral Monte Carlo simulations of quark-gluon plasma
NASA Astrophysics Data System (ADS)
Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Fortov, V. E.; Levashov, P. R.
2012-02-01
Thermodynamic properties of a strongly coupled quark-gluon plasma (QGP) of constituent quasiparticles are studied by a color path-integral Monte Carlo simulations (CPIMC). For our simulations we have presented QGP partition function in the form of color path integral with new relativistic measure instead of Gaussian one used in Feynman and Wiener path integrals. For integration over color variable we have also developed procedure of sampling color variables according to the group SU(3) Haar measure. It is shown that this method is able to reproduce the available quantum lattice chromodynamics (QCD) data.
Silicon Photonic Switches Hybrid-Integrated With CMOS Drivers
Alexander V. Rylyakov; Clint L. Schow; Benjamin G. Lee; William M. J. Green; Solomon Assefa; Fuad E. Doany; Min Yang; Joris Van Campenhout; Christopher V. Jahnes; Jeffrey A. Kash; Yurii A. Vlasov
2012-01-01
This paper describes the design and measured performance of three different silicon photonic switches: a 2$\\\\,\\\\times\\\\,$ 2 switch, a 1$\\\\,\\\\times\\\\,$ 2 switch, and a 4$\\\\,\\\\times\\\\,$ 4 switch. All of the devices have been hybrid integrated with a corresponding custom 90-nm CMOS driver. The 2 $\\\\,\\\\times\\\\,$2 switch is based on a wavelength-insensitive Mach–Zehnder interferometer (WIMZ) and the 1 $\\\\,\\\\times\\\\,$2 is based
HRMC_1.1: Hybrid Reverse Monte Carlo method with silicon and carbon potentials
NASA Astrophysics Data System (ADS)
Opletal, G.; Petersen, T. C.; O'Malley, B.; Snook, I. K.; McCulloch, D. G.; Yarovsky, I.
2011-02-01
The Hybrid Reverse Monte Carlo (HRMC) code models the atomic structure of materials via the use of a combination of constraints including experimental diffraction data and an empirical energy potential. This energy constraint is in the form of either the Environment Dependent Interatomic Potential (EDIP) for carbon and silicon and the original and modified Stillinger-Weber potentials applicable to silicon. In this version, an update is made to correct an error in the EDIP carbon energy calculation routine. New version program summaryProgram title: HRMC version 1.1 Catalogue identifier: AEAO_v1_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAO_v1_1.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 36 991 No. of bytes in distributed program, including test data, etc.: 907 800 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Any computer capable of running executables produced by the g77 Fortran compiler. Operating system: Unix, Windows RAM: Depends on the type of empirical potential use, number of atoms and which constraints are employed. Classification: 7.7 Catalogue identifier of previous version: AEAO_v1_0 Journal reference of previous version: Comput. Phys. Comm. 178 (2008) 777 Does the new version supersede the previous version?: Yes Nature of problem: Atomic modelling using empirical potentials and experimental data. Solution method: Monte Carlo Reasons for new version: An error in a term associated with the calculation of energies using the EDIP carbon potential which results in incorrect energies. Summary of revisions: Fix to correct brackets in the two body part of the EDIP carbon potential routine. Additional comments: The code is not standard FORTRAN 77 but includes some additional features and therefore generates errors when compiled using the Nag95 compiler. It does compile successfully with the GNU g77 compiler ( http://www.gnu.org/software/fortran/fortran.html). Running time: Depends on the type of empirical potential use, number of atoms and which constraints are employed. The test included in the distribution took 37 minutes on a DEC Alpha PC.
Graphene/Si CMOS Hybrid Hall Integrated Circuits
Huang, Le; Xu, Huilong; Zhang, Zhiyong; Chen, Chengying; Jiang, Jianhua; Ma, Xiaomeng; Chen, Bingyan; Li, Zishen; Zhong, Hua; Peng, Lian-Mao
2014-01-01
Graphene/silicon CMOS hybrid integrated circuits (ICs) should provide powerful functions which combines the ultra-high carrier mobility of graphene and the sophisticated functions of silicon CMOS ICs. But it is difficult to integrate these two kinds of heterogeneous devices on a single chip. In this work a low temperature process is developed for integrating graphene devices onto silicon CMOS ICs for the first time, and a high performance graphene/CMOS hybrid Hall IC is demonstrated. Signal amplifying/process ICs are manufactured via commercial 0.18?um silicon CMOS technology, and graphene Hall elements (GHEs) are fabricated on top of the passivation layer of the CMOS chip via a low-temperature micro-fabrication process. The sensitivity of the GHE on CMOS chip is further improved by integrating the GHE with the CMOS amplifier on the Si chip. This work not only paves the way to fabricate graphene/Si CMOS Hall ICs with much higher performance than that of conventional Hall ICs, but also provides a general method for scalable integration of graphene devices with silicon CMOS ICs via a low-temperature process. PMID:24998222
Copula Based Monte Carlo Integration in Financial Problems
Sancetta, Alessio
2006-03-14
positive random variables. For example, if we were to model daily financial returns, the modified Weibull distribution or the double gamma could be good choices (e.g. Knight et al., 1995, and Laherrere and Sornette, 1998). The exponential distribution... would usually do with the standard MC integral, or to construct quasi-random numbers in order to reduce the number of simulations (e.g. Spanier and Maize, 1994). Consider the expectation of some function with respect to the multivariate Gaussian density...
Extrapolated high-order propagators for path integral Monte Carlo simulations
NASA Astrophysics Data System (ADS)
Zillich, Robert E.; Mayrhofer, Johannes M.; Chin, Siu A.
2010-01-01
We present a new class of high-order imaginary time propagators for path integral Monte Carlo simulations that require no higher order derivatives of the potential nor explicit quadratures of Gaussian trajectories. Higher orders are achieved by an extrapolation of the primitive second-order propagator involving subtractions. By requiring all terms of the extrapolated propagator to have the same Gaussian trajectory, the subtraction only affects the potential part of the path integral. The resulting violation of positivity has surprisingly little effects on the accuracy of the algorithms at practical time steps. Thus in principle, arbitrarily high order algorithms can be devised for path integral Monte Carlo simulations. We verified the fourth, sixth, and eighth order convergences of these algorithms by solving for the ground state energy and pair distribution function of liquid H4e, which is representative of a dense, and strongly interacting, quantum many-body system.
Exploiting symmetries for exponential error reduction in path integral Monte Carlo
NASA Astrophysics Data System (ADS)
Della Morte, Michele; Giusti, Leonardo
2009-06-01
The path integral of a quantum system with an exact symmetry can be written as a sum of functional integrals each giving the contribution from quantum states with definite symmetry properties. We propose a strategy to compute each of them, normalized to the one with vacuum quantum numbers, by a Monte Carlo procedure whose cost increases power-like with the time extent of the lattice. This is achieved thanks to a multi-level integration scheme, inspired by the transfer matrix formalism, which exploits the symmetry and the locality in time of the underlying statistical system. As a result the cost of computing the lowest energy level in a given channel, its multiplicity and its matrix elements is exponentially reduced with respect to the standard path-integral Monte Carlo. We test the strategy with a one-dimensional harmonic oscillator, by computing the ratio of the parity odd over the parity even functional integrals and the two-point correlation function. The cost of the simulations scales as expected. In particular the effort for computing the lowest energy eigenvalue in the parity odd sector grows linearly with the time extent. At a fixed CPU time, the statistical error on the two-point correlation function is exponentially reduced with respect to the standard Monte Carlo procedure, and at large time distances it is lowered by many orders of magnitude.
SU-E-T-117: Dose to Organs Outside of CT Scan Range- Monte Carlo and Hybrid Phantom Approach
Pelletier, C; Jung, J [East Carolina University, Greenville, NC (United States); Lee, C [University of Michigan, Ann Arbor, MI (United States); Kim, J [University of Pittsburgh Medical Center, Pittsburgh, PA (United States); Lee, C [National Cancer Institute, Rockville, MD (United States)
2014-06-01
Purpose: Epidemiological study of second cancer risk for cancer survivors often requires the dose to normal tissues located outside the anatomy covered by radiological imaging, which is usually limited to tumor and organs at risk. We have investigated the feasibility of using whole body computational human phantoms for estimating out-of-field organ doses for patients treated by Intensity Modulated Radiation Therapy (IMRT). Methods: Identical 7-field IMRT prostate plans were performed using X-ray Voxel Monte Carlo (XVMC), a radiotherapy-specific Monte Carlo transport code, on the computed tomography (CT) images of the torso of an adult male patient (175 cm height, 66 kg weight) and an adult male hybrid computational phantom with the equivalent body size. Dose to the liver, right lung, and left lung were calculated and compared. Results: Considerable differences are seen between the doses calculated by XVMC for the patient CT and the hybrid phantom. One major contributing factor is the treatment method, deep inspiration breath hold (DIBH), used for this patient. This leads to significant differences in the organ position relative to the treatment isocenter. The transverse distances from the treatment isocenter to the inferior border of the liver, left lung, and right lung are 19.5cm, 29.5cm, and 30.0cm, respectively for the patient CT, compared with 24.3cm, 36.6cm, and 39.1cm, respectively, for the hybrid phantom. When corrected for the distance, the mean doses calculated using the hybrid phantom are within 28% of those calculated using the patient CT. Conclusion: This study showed that mean dose to the organs located in the missing CT coverage can be reconstructed by using whole body computational human phantoms within reasonable dosimetric uncertainty, however appropriate corrections may be necessary if the patient is treated with a technique that will significantly deform the size or location of the organs relative to the hybrid phantom.
A. F. W. van Hameren
2001-01-10
Discrepancies play an important role in the study of uniformity properties of point sets. Their probability distributions are a help in the analysis of the efficiency of the Quasi Monte Carlo method of numerical integration, which uses point sets that are distributed more uniformly than sets of independently uniformly distributed random points. In this thesis, generating functions of probability distributions of quadratic discrepancies are calculated using techniques borrowed from quantum field theory. The second part of this manuscript deals with the application of the Monte Carlo method to phase space integration, and in particular with an explicit example of importance sampling. It concerns the integration of differential cross sections of multi-parton QCD-processes, which contain the so-called kinematical antenna pole structures. The algorithm is presented and compared with RAMBO, showing a substantial reduction in computing time. In behalf of completeness of the thesis, short introductions to probability theory, Feynman diagrams and the Monte Carlo method of numerical integration are included.
Integration of hybrid silicon lasers and electroabsorption modulators.
Sysak, Matthew N; Anthes, Joel O; Bowers, John E; Raday, Omri; Jones, Richard
2008-08-18
We present an integration platform based on quantum well intermixing for multi-section hybrid silicon lasers and electroabsorption modulators. As a demonstration of the technology, we have fabricated discrete sampled grating DBR lasers and sampled grating DBR lasers integrated with InGaAsP/InP electroabsorption modulators. The integrated sampled grating DBR laser-modulators use the as-grown III-V bandgap for optical gain, a 50 nm blue shifted bandgap for the electrabosprtion modulators, and an 80 nm blue shifted bandgap for low loss mirrors. Laser continuous wave operation up to 45 ?C is achieved with output power >1.0 mW and threshold current of <50 mA. The modulator bandwidth is >2GHz with 5 dB DC extinction. PMID:18711484
NASA Astrophysics Data System (ADS)
Driver, K. P.; Militzer, B.
2012-03-01
We develop an all-electron path integral Monte Carlo method with free-particle nodes for warm dense matter and apply it to water and carbon plasmas. We thereby extend path integral Monte Carlo studies beyond hydrogen and helium to elements with core electrons. Path integral Monte Carlo results for pressures, internal energies, and pair-correlation functions compare well with density functional theory molecular dynamics calculations at temperatures of (2.5-7.5)×105K, and both methods together form a coherent equation of state over a density-temperature range of 3-12g/cm3 and 104-109K.
Monte Carlo thermal model of an integrating light pipe for rapid thermal processing
Thomas, J.C. [Ball Aerospace and Technologies Corp., Broomfield, CO (United States); DeWitt, D.P. [Purdue Univ., West Lafayette, IN (United States). School of Mechanical Engineering
1996-12-01
A Monte Carlo model is developed to simulate transient wafer heating as a function of system parameters in a kaleidoscope- or integrating light-pipe type cavity with square cross-section. Trends in wafer temperature uniformity are examined as a function of length-to-width ratio, cavity width, and the number of heating lamps. The effect on temperature determination by a radiometer placed in the bottom end wall of the cavity is simulated.
Path-integral Monte Carlo simulation of helium at negative pressures
Gregory H. Bauer; David M. Ceperley; Nigel Goldenfeld
2000-01-01
Path integral Monte Carlo (PIMC) simulations of liquid helium at negative\\u000apressure have been carried out for a temperature range from the critical\\u000atemperature to below the superfluid transition. We have calculated the\\u000atemperature dependence of the spinodal line as well as the pressure dependence\\u000aof the isothermal sound velocity in the region of the spinodal. We discuss the\\u000aslope
Iterative Monte Carlo path integral with optimal grids from whole-necklace sampling
NASA Astrophysics Data System (ADS)
Jadhao, Vikram; Makri, Nancy
2010-09-01
The efficiency of the iterative Monte Carlo (IMC) path integral methodology for complex time correlation functions is increased through the use of optimal grids, which are sampled from paths that span the entire path integral necklace. The two-bead marginal distributions required in each step of the IMC iteration are obtained from a recursive procedure. Applications to one-dimensional and multi-dimensional model systems illustrate the enhancement in stability effected by the use of grids based on whole-necklace sampling.
Hybrid polymer photonic crystal fiber with integrated chalcogenide glass nanofilms.
Markos, Christos; Kubat, Irnis; Bang, Ole
2014-01-01
The combination of chalcogenide glasses with polymer photonic crystal fibers (PCFs) is a difficult and challenging task due to their different thermo-mechanical material properties. Here we report the first experimental realization of a hybrid polymer-chalcogenide PCF with integrated As2S3 glass nanofilms at the inner surface of the air-channels of a poly-methyl-methacrylate (PMMA) PCF. The integrated high refractive index glass films introduce distinct antiresonant transmission bands in the 480-900 nm wavelength region. We demonstrate that the ultra-high Kerr nonlinearity of the chalcogenide glass makes the polymer PCF nonlinear and provides a possibility to shift the transmission band edges as much as 17 nm by changing the intensity. The proposed fabrication technique constitutes a new highway towards all-fiber nonlinear tunable devices based on polymer PCFs, which at the moment is not possible with any other fabrication method. PMID:25317501
Better HMC integrators for dynamical simulations
M.A. Clark, Balint Joo, A.D. Kennedy, P.J. Silva
2010-06-01
We show how to improve the molecular dynamics step of Hybrid Monte Carlo, both by tuning the integrator using Poisson brackets measurements and by the use of force gradient integrators. We present results for moderate lattice sizes.
Hybrid integrated optic modules for real-time signal processing
NASA Astrophysics Data System (ADS)
Tsai, C. S.
1984-03-01
The most recent progress on four relatively new hybrid integrated optic device modules in LiNbO3 waveguides and one in YIG/GGG waveguide that are currently being studied are discussed. The five hybrid modules include a time-integrating acoustooptic correlator, a channel waveguide acoustooptic frequency shifter/modulator, an electrooptic channel waveguide total internal reflection moculator/switch, an electrooptic analog-to-digital converter using a Fabry-Perot modulator array, and a noncollinear magnetooptic modulator using magnetostatic surface waves. All of these devices possess the desirable characteristics of very large bandwidth (GHz or higher), very small substrate size along the optical path (typically 1.5 cm or less), single-mode optical propagation, and low drive power requirement. The devices utilize either acoustooptic, electrooptic or magnetooptic effects in planar or channel waveguides and, therefore, act as efficient interface devices between a light wave and temporal signals. Major areas of application lie in wideband multichannel optical real-time signal processing and communications. Some of the specific applications include spectral analysis and correlation of radio frequency (RF) signals, fiber-optic sensing, optical computing and multiport switching/routing, and analog-to-digital conversion of wide RF signals.
NASA Astrophysics Data System (ADS)
Eylenceo?lu, E.; Rafatov, I.; Kudryavtsev, A. A.
2015-01-01
Two-dimensional hybrid Monte Carlo-fluid numerical code is developed and applied to model the dc glow discharge. The model is based on the separation of electrons into two parts: the low energetic (slow) and high energetic (fast) electron groups. Ions and slow electrons are described within the fluid model using the drift-diffusion approximation for particle fluxes. Fast electrons, represented by suitable number of super particles emitted from the cathode, are responsible for ionization processes in the discharge volume, which are simulated by the Monte Carlo collision method. Electrostatic field is obtained from the solution of Poisson equation. The test calculations were carried out for an argon plasma. Main properties of the glow discharge are considered. Current-voltage curves, electric field reversal phenomenon, and the vortex current formation are developed and discussed. The results are compared to those obtained from the simple and extended fluid models. Contrary to reports in the literature, the analysis does not reveal significant advantages of existing hybrid methods over the extended fluid model.
NASA Technical Reports Server (NTRS)
Ellison, Donald C.; Giacalone, J.; Burgess, D.; Schwartz, S. J.
1993-01-01
We have made a direct comparison between two different computer simulations of a plane, parallel, collisionless shock including particle acceleration to energies typical of those of diffuse ions observed at the earth bow shock. Despite the fact that the one-dimensional hybrid and Monte Carlo techniques employ entirely different algorithms, they give surprisingly close agreement in the overall shapes of the complete distribution functions for protons as well as heavier ions. Both methods show that energetic ions emerge smoothly from the background thermal plasma with approximately the same relative injection rate and that the fraction of the incoming plasma's energy flux that is converted into downstream enthalpy flux of the accelerated population (i.e., the acceleration efficiency) is similar in the two cases. The fraction of the downstream proton distribution made up of superthermal particles is quite large, with at least 10% of the energy flux going into protons with energies above 10 keV. In addition, an upstream precursor, produced by backstreaming energetic particles, is present in both shocks, although the Monte Carlo precursor is considerably longer than that produced in the hybrid shock. These results offer convincing evidence that, at least in these ways, the two simulations are consistent in their description of parallel shock structure and particle acceleration, and they lay the groundwork for development of shock models employing a combination of both methods.
S. M. Mesli; M. Habchi; M. Kotbi; H. Xu
2013-03-25
The choice of appropriate interaction models is among the major disadvantages of conventional methods such as molecular dynamics and Monte Carlo simulations. On the other hand, the so-called reverse Monte Carlo (RMC) method, based on experimental data, can be applied without any interatomic and/or intermolecular interactions. The RMC results are accompanied by artificial satellite peaks. To remedy this problem, we use an extension of the RMC algorithm, which introduces an energy penalty term into the acceptance criteria. This method is referred to as the hybrid reverse Monte Carlo (HRMC) method. The idea of this paper is to test the validity of a combined potential model of coulomb and Lennard-Jones in a fluoride glass system BaMnMF_{7} (M=Fe,V) using HRMC method. The results show a good agreement between experimental and calculated characteristics, as well as a meaningful improvement in partial pair distribution functions. We suggest that this model should be used in calculating the structural properties and in describing the average correlations between components of fluoride glass or a similar system. We also suggest that HRMC could be useful as a tool for testing the interaction potential models, as well as for conventional applications.
Hybrid integrated metro ring node subsystem on a chip
NASA Astrophysics Data System (ADS)
Gerhardt, Reinald; Fujita, Junichiro; Radojevic, Antonije M.; Zhuromskyy, Oleksandr; Eldada, Louay A.
2003-07-01
We report on a hybrid integrated metro ring node subsystem on a chip that consists of an array of four independent reconfigurable optical add-drop circuits, each with power monitoring and automatic load balancing, and supporting shared and dedicated protection protocols in two-fiber metro ring optical networks. The four-channel metro ring node chip has polymeric optical waveguiding circuitry, thermally actuated with heaters consisting of resistive strips of metal. Photodiode arrays are flip-chip mounted on top of 45° mirrors cut in the waveguides of optical power taps. The mirrors are fabricated by Excimer laser ablation of the polymer followed by smoothing and metalization. The non-integrated implementation of a metro ring node uses 48 discrete elements, namely 8 1×2 switches, 8 2×2 switches, 8 VOAs, 12 taps, and 12 photodiodes. The proposed integrated solution is an exemplary embodiment of the benefits of optoelectronic integration as it provides, when compared to the discrete solution, significant cost reduction, space savings, lower electrical power consumption, higher reliability (fewer devices, runs cooler), and fewer board-level fiber interconnects.
Quantum Mechanical Single Molecule Partition Function from PathIntegral Monte Carlo Simulations
Chempath, Shaji; Bell, Alexis T.; Predescu, Cristian
2006-10-01
An algorithm for calculating the partition function of a molecule with the path integral Monte Carlo method is presented. Staged thermodynamic perturbation with respect to a reference harmonic potential is utilized to evaluate the ratio of partition functions. Parallel tempering and a new Monte Carlo estimator for the ratio of partition functions are implemented here to achieve well converged simulations that give an accuracy of 0.04 kcal/mol in the reported free energies. The method is applied to various test systems, including a catalytic system composed of 18 atoms. Absolute free energies calculated by this method lead to corrections as large as 2.6 kcal/mol at 300 K for some of the examples presented.
Modeling integrated cellular machinery using hybrid Petri-Boolean networks.
Berestovsky, Natalie; Zhou, Wanding; Nagrath, Deepak; Nakhleh, Luay
2013-01-01
The behavior and phenotypic changes of cells are governed by a cellular circuitry that represents a set of biochemical reactions. Based on biological functions, this circuitry is divided into three types of networks, each encoding for a major biological process: signal transduction, transcription regulation, and metabolism. This division has generally enabled taming computational complexity dealing with the entire system, allowed for using modeling techniques that are specific to each of the components, and achieved separation of the different time scales at which reactions in each of the three networks occur. Nonetheless, with this division comes loss of information and power needed to elucidate certain cellular phenomena. Within the cell, these three types of networks work in tandem, and each produces signals and/or substances that are used by the others to process information and operate normally. Therefore, computational techniques for modeling integrated cellular machinery are needed. In this work, we propose an integrated hybrid model (IHM) that combines Petri nets and Boolean networks to model integrated cellular networks. Coupled with a stochastic simulation mechanism, the model simulates the dynamics of the integrated network, and can be perturbed to generate testable hypotheses. Our model is qualitative and is mostly built upon knowledge from the literature and requires fine-tuning of very few parameters. We validated our model on two systems: the transcriptional regulation of glucose metabolism in human cells, and cellular osmoregulation in S. cerevisiae. The model produced results that are in very good agreement with experimental data, and produces valid hypotheses. The abstract nature of our model and the ease of its construction makes it a very good candidate for modeling integrated networks from qualitative data. The results it produces can guide the practitioner to zoom into components and interconnections and investigate them using such more detailed mathematical models. PMID:24244124
Golden Ratio Versus Pi as Random Sequence Sources for Monte Carlo Integration
NASA Technical Reports Server (NTRS)
Sen, S. K.; Agarwal, Ravi P.; Shaykhian, Gholam Ali
2007-01-01
We discuss here the relative merits of these numbers as possible random sequence sources. The quality of these sequences is not judged directly based on the outcome of all known tests for the randomness of a sequence. Instead, it is determined implicitly by the accuracy of the Monte Carlo integration in a statistical sense. Since our main motive of using a random sequence is to solve real world problems, it is more desirable if we compare the quality of the sequences based on their performances for these problems in terms of quality/accuracy of the output. We also compare these sources against those generated by a popular pseudo-random generator, viz., the Matlab rand and the quasi-random generator ha/ton both in terms of error and time complexity. Our study demonstrates that consecutive blocks of digits of each of these numbers produce a good random sequence source. It is observed that randomly chosen blocks of digits do not have any remarkable advantage over consecutive blocks for the accuracy of the Monte Carlo integration. Also, it reveals that pi is a better source of a random sequence than theta when the accuracy of the integration is concerned.
Interacting electrons in one dimension: a path integral Monte Carlo study
NASA Astrophysics Data System (ADS)
Lyubartsev, Alexander P.
2007-06-01
Path integral Monte Carlo simulations have been carried out for a system of interacting fermionic particles in one dimension. Due to the fact that the sign problem can be completely eliminated for one-dimensional systems, such simulations allow one to obtain accurate energies and particle densities in arbitrary external potentials. Two cases were considered: electrons in the field of a uniform neutralizing background and in an effective field of atoms on a lattice. In the latter case, a clear asymmetry of the charge density distribution of conducting electrons and holes has been observed.
Path-Integral Monte Carlo Simulations of the Ideal Strength of HCP Helium 4
NASA Astrophysics Data System (ADS)
de Koning, Maurice; Josué Landinez Borda, Edgar
2012-02-01
Using path-integral Monte Carlo simulations we assess the ideal strength of solid He-4 in its HCP phase. This fundamental material parameter is defined as the stress necessary to produce irreversible deformation in a defect-free crystal. For this purpose we impose slowly increasing homogeneous deformations to defect-free He-4 crystals and measure the corresponding internal stress state. In this manner, we determine the ideal shear strength in the basal plane as a function of the shear orientation, as well as the tensile and compressive strength perpendicular to this plane. Our results establish upper bounds to the strength of real HCP He-4 crystals.
Path-Integral Monte Carlo Simulation of the Warm Dense Homogeneous Electron Gas
NASA Astrophysics Data System (ADS)
Brown, Ethan W.; Clark, Bryan K.; DuBois, Jonathan L.; Ceperley, David M.
2013-04-01
We perform calculations of the 3D finite-temperature homogeneous electron gas in the warm-dense regime (rs?(3/4?n)1/3a0-1=1.0-40.0 and ??T/TF=0.0625-8.0) using restricted path-integral Monte Carlo simulations. Precise energies, pair correlation functions, and structure factors are obtained. For all densities, we find a significant discrepancy between the ground state parametrized local density approximation and our results around TF. These results can be used as a benchmark for developing finite-temperature density functionals, as well as input for orbital-free density function theory formulations.
Path-Integral Monte Carlo Simulations of Ideal Strength and Peierls Stress in HCP 4He
NASA Astrophysics Data System (ADS)
Landinez Borda, Edgar Josué; de Koning, Maurice
2013-03-01
The ideal strength of a crystal is defined as the stress required to induce plastic deformation in a defect-free crystal. It is a theoretical upper bound to the strength of real crystals. The Peierls stress, on the other hand, is the minimum stress required to move a lattice dislocation and produce defect-mediated deformation. Here we present results for both quantities in HCP 4He as obtained from a series of Path-integral Monte Carlo simulations and discuss them in terms of its deformation behavior.
Energy levels and expectation values via accelerated path integral Monte Carlo
NASA Astrophysics Data System (ADS)
Stojiljkovi?, D.; Bogojevi?, A.; Balaž, A.
2008-08-01
A recently developed method systematically improved the convergence of generic path integrals for transition amplitudes, partition functions, expectation values and energy spectra. This was achieved by analytically constructing a hierarchy of discretized effective actions indexed by a level number p and converging to the continuum limit as 1/Np. Here we apply the above general method to numerical calculations using Metropolis Monte Carlo simulations of energy expectation values and energy spectra. We analyze and compare the ensuing increase in efficiency of several orders of magnitude.
Path Integral Monte Carlo Calculation of Momentum Distribution in Solid 4He
NASA Astrophysics Data System (ADS)
Rota, R.; Boronat, J.
2011-02-01
We perform calculations of the momentum distribution n( k) in solid 4He by means of path integral Monte Carlo methods. We see that, in perfect crystals, n( k) does not depend on temperature T and that is different from the classical Gaussian shape of the Maxwell-Boltzmann distribution, even though these discrepancies decrease when the density of the system increases. In crystals presenting vacancies, we see that for T?0.75 K, n( k) presents the same behavior as in the perfect crystal, but, at lower T, it presents a peak when k?0.
NASA Technical Reports Server (NTRS)
Wolynes, Peter G.
1987-01-01
Nonadiabatic transitions are central to many areas of chemical and condensed matter physics, ranging from biological electron transfer to the optical properties of one-dimensional conductors. Here, a path integral Monte Carlo method is used to simulate such transitions, based on the observation that nonadiabatic rate coefficients are often dominated by saddle point trajectories that correspond to an imaginary time. Simple analytic theories can be used to continue these imaginary time correlation functions to determine rate coefficients. The advantages and drawbacks of this approach are discussed.
Marco Saraniti; Stephen M. Goodnick
2000-01-01
We present a fullband cellular automaton (CA) code for simulation of electron and hole transport in Si and GaAs. In this implementation, the entire Brillouin zone is discretized using a nonuniform mesh in k-space, and a transition table is generated between all initial and final states on the mesh, greatly simplifying the final state selection of the conventional Monte Carlo
Andújar, C; Arribas, P; Ruiz, C; Serrano, J; Gómez-Zurita, J
2014-09-01
In species differentiation, characters may not diverge synchronously, and there are also processes that shuffle character states in lineages descendant from a common ancestor. Species are thus expected to show some degree of incongruence among characters; therefore, taxonomic delimitation can benefit from integrative approaches and objective strategies that account for character conflict. We illustrate the potential of exploiting conflict for species delimitation in a study case of ground beetles of the subgenus Carabus (Mesocarabus), where traditional taxonomy does not accurately delimit species. The molecular phylogenies of four mitochondrial and three nuclear genes, cladistic analysis of the aedeagus, ecological niche divergence and morphometry of pronotal shape in more than 500 specimens of Mesocarabus show that these characters are not fully congruent. For these data, a three-step operational strategy is proposed for species delimitation by (i) delineating candidate species based on the integration of incongruence among conclusive lines of evidence, (ii) corroborating candidate species with inconclusive lines of evidence and (iii) refining a final species proposal based on an integrated characterization of candidate species based on the evolutionary analysis of incongruence. This procedure provided a general understanding of the reticulate process of hybridization and introgression acting on Mesocarabus and generated the hypothesis of seven Mesocarabus species, including two putative hybrid lineages. Our work emphasizes the importance of incorporating critical analyses of character and phylogenetic conflict to infer both the evolutionary history and species boundaries through an integrative taxonomic approach. PMID:24828576
Effect of Nonlinearity in Hybrid Kinetic Monte Carlo-Continuum Models
Balter, Ariel I.; Lin, Guang; Tartakovsky, Alexandre M.
2012-04-23
Recently there has been interest in developing efficient ways to model heterogeneous surface reactions with hybrid computational models that couple a KMC model for a surface to a finite difference model for bulk diffusion in a continuous domain. We consider two representative problems that validate a hybrid method and also show that this method captures the combined effects of nonlinearity and stochasticity. We first validate a simple deposition/dissolution model with a linear rate showing that the KMC-continuum hybrid agrees with both a fully deterministic model and its analytical solution. We then study a deposition/dissolution model including competitive adsorption, which leads to a nonlinear rate, and show that, in this case, the KMC-continuum hybrid and fully deterministic simulations do not agree. However, we are able to identify the difference as a natural result of the stochasticity coming from the KMC surface process. Because KMC captures inherent fluctuations, we consider it to be more realistic than a purely deterministic model. Therefore, we consider the KMC-continuum hybrid to be more representative of a real system.
Castin, N; Pascuet, M I; Malerba, L
2011-08-14
We simulate the coherent stage of Cu precipitation in ?-Fe with an atomistic kinetic Monte Carlo (AKMC) model. The vacancy migration energy as a function of the local chemical environment is provided on-the-fly by a neural network, trained with high precision on values calculated with the nudged elastic band method, using a suitable interatomic potential. To speed up the simulation, however, we modify the standard AKMC algorithm by treating large Cu clusters as objects, similarly to object kinetic Monte Carlo approaches. Seamless matching between the fully atomistic and the coarse-grained approach is achieved again by using a neural network, that provides all stability and mobility parameters for large Cu clusters, after training on atomistically informed results. The resulting hybrid algorithm allows long thermal annealing experiments to be simulated, within a reasonable CPU time. The results obtained are in very good agreement with several series of experimental data available from the literature, spanning over different conditions of temperature and alloy composition. We deduce from these results and relevant parametric studies that the mobility of Cu clusters containing one vacancy plays a central role in the precipitation mechanism. PMID:21842938
Elastic constants of hcp 4He: Path-integral Monte Carlo results versus experiment
NASA Astrophysics Data System (ADS)
Ardila, Luis Aldemar Peña; Vitiello, Silvio A.; de Koning, Maurice
2011-09-01
The elastic constants of hcp 4He are computed using the path-integral Monte Carlo (PIMC) method. The stiffness coefficients are obtained by imposing different distortions to a periodic cell containing 180 atoms, followed by measurement of the elements of the corresponding stress tensor. For this purpose an appropriate path-integral expression for the stress tensor observable is derived and implemented into the pimc++ package. In addition to allowing the determination of the elastic stiffness constants, this development also opens the way to an explicit atomistic determination of the Peierls stress for dislocation motion using the PIMC technique. A comparison of the results to available experimental data shows an overall good agreement of the density dependence of the elastic constants, with the single exception of C13. Additional calculations for the bcc phase, on the other hand, show good agreement for all elastic constants.
On processed splitting methods and high-order actions in path-integral Monte Carlo simulations
NASA Astrophysics Data System (ADS)
Casas, Fernando
2010-10-01
Processed splitting methods are particularly well adapted to carry out path-integral Monte Carlo (PIMC) simulations: since one is mainly interested in estimating traces of operators, only the kernel of the method is necessary to approximate the thermal density matrix. Unfortunately, they suffer the same drawback as standard, nonprocessed integrators: kernels of effective order greater than two necessarily involve some negative coefficients. This problem can be circumvented, however, by incorporating modified potentials into the composition, thus rendering schemes of higher effective order. In this work we analyze a family of fourth-order schemes recently proposed in the PIMC setting, paying special attention to their linear stability properties, and justify their observed behavior in practice. We also propose a new fourth-order scheme requiring the same computational cost but with an enlarged stability interval.
Data assimilation using a GPU accelerated path integral Monte Carlo approach
NASA Astrophysics Data System (ADS)
Quinn, John C.; Abarbanel, Henry D. I.
2011-09-01
The answers to data assimilation questions can be expressed as path integrals over all possible state and parameter histories. We show how these path integrals can be evaluated numerically using a Markov Chain Monte Carlo method designed to run in parallel on a graphics processing unit (GPU). We demonstrate the application of the method to an example with a transmembrane voltage time series of a simulated neuron as an input, and using a Hodgkin-Huxley neuron model. By taking advantage of GPU computing, we gain a parallel speedup factor of up to about 300, compared to an equivalent serial computation on a CPU, with performance increasing as the length of the observation time used for data assimilation increases.
State and parameter estimation using Monte Carlo evaluation of path integrals
NASA Astrophysics Data System (ADS)
Quinn, John C.; Abarbanel, Henry D. I.
2010-10-01
Transferring information from observations of a dynamical system to estimate the fixed parameters and unobserved states of a system model can be formulated as the evaluation of a discrete time path integral in model state space. The observations serve as a guiding potential working with the dynamical rules of the model to direct system orbits in state space. The path integral representation permits direct numerical evaluation of the conditional mean path through the state space as well as conditional moments about this mean. Using a Monte Carlo method for selecting paths through state space we show how these moments can be evaluated and demonstrate in an interesting model system the explicit influence of the role of transfer of information from the observations. We address the question of how many observations are required to estimate the unobserved state variables, and we examine the assumptions of Gaussianity of the underlying conditional probability.
Monte Carlo Simulations of Globular Cluster Evolution. IV. Direct Integration of Strong Interactions
John M. Fregeau; Frederic A. Rasio
2006-12-06
We study the dynamical evolution of globular clusters containing populations of primordial binaries, using our newly updated Monte Carlo cluster evolution code with the inclusion of direct integration of binary scattering interactions. We describe the modifications we have made to the code, as well as improvements we have made to the core Monte Carlo method. We present several test calculations to verify the validity of the new code, and perform many comparisons with previous analytical and numerical work in the literature. We simulate the evolution of a large grid of models, with a wide range of initial cluster profiles, and with binary fractions ranging from 0 to 1, and compare with observations of Galactic globular clusters. We find that our code yields very good agreement with direct N-body simulations of clusters with primordial binaries, but yields some results that differ significantly from other approximate methods. Notably, the direct integration of binary interactions reduces their energy generation rate relative to the simple recipes used in Paper III, and yields smaller core radii. Our results for the structural parameters of clusters during the binary-burning phase are now in the tail of the range of parameters for observed clusters, implying that either clusters are born significantly more or less centrally concentrated than has been previously considered, or that there are additional physical processes beyond two-body relaxation and binary interactions that affect the structural characteristics of clusters.
Incremental adaptive integration of layers of a hybrid control architecture
Matthew Powers; Tucker Balch
2010-01-01
Hybrid deliberative-reactive control architectures are a popular and effective approach to the control of robotic navigation applications. However, due to the fundamental differences in the design of the reactive and deliberative layers, the design of hybrid control architectures can pose significant difficulties. We propose a novel approach to improving system-level performance of hybrid control architectures by incrementally improving the deliberative
Application of ECSPN to RAMS modeling and analysis of hybrid drive systems
Steffen Nebel; A. Dieter; P. Muller; B. Bertsche
2010-01-01
In our paper we present a modeling and simulation approach based on a class of Extended Colored Stochastic Petri Nets and a Monte Carlo Simulation to analyze and optimize hybrid car systems. The approach allows the modeling of various functional dependencies between the components of a hybrid car drive system and the integration of lifetime models. The Monte Carlo simulation
Integrated Hybrid Lasers and Amplifiers on a Silicon Richard Jones, Matthew N. Sysak
Bowers, John
temperature plasma-assisted bonding step [2]. After bonding the InP substrate is removed and Mesa's are etched of the hybrid AlGaInAs-silicon platform where InP active and silicon passive components are integrated using and low cost waveguides to InP. Here an overview of our recent research into hybrid silicon devices
Path Integral Monte Carlo finite-temperature electronic structure of quantum dots
NASA Astrophysics Data System (ADS)
Leino, Markku; Rantala, Tapio T.
2003-03-01
Quantum Monte Carlo methods allow a straightforward procedure for evaluation of electronic structures with a proper treatment of electronic correlations. This can be done even at finite temperatures [1]. We apply the Path Integral Monte Carlo (PIMC) simulation method [2] for one and two electrons in a single and double quantum dots. With this approach we evaluate the electronic distributions and correlations, and finite temperature effects on those. Temperature increase broadens the one-electron distribution as expected. This effect is smaller for correlated electrons than for single ones. The simulated one and two electron distributions of a single and two coupled quantum dots are also compared to those from experiments and other theoretical (0 K) methods [3]. Computational capacity is found to become the limiting factor in simulations with increasing accuracy. This and other essential aspects of PIMC and its capability in this type of calculations are also discussed. [1] R.P. Feynman: Statistical Mechanics, Addison Wesley, 1972. [2] D.M. Ceperley, Rev.Mod.Phys. 67, 279 (1995). [3] M. Pi, A. Emperador and M. Barranco, Phys.Rev.B 63, 115316 (2001).
NASA Astrophysics Data System (ADS)
Shim, Sangwoo; Aspuru-Guzik, Alán
2012-12-01
The reduced density matrix of excitons coupled to a phonon bath at a finite temperature is studied using the path integral Monte Carlo method. Appropriate choices of estimators and importance sampling schemes are crucial to the performance of the Monte Carlo simulation. We show that by choosing the population-normalized estimator for the reduced density matrix, an efficient and physically-meaningful sampling function can be obtained. In addition, the nonadiabatic phonon probability density is obtained as a byproduct during the sampling procedure. For importance sampling, we adopted the Metropolis-adjusted Langevin algorithm. The analytic expression for the gradient of the target probability density function associated with the population-normalized estimator cannot be obtained in closed form without a matrix power series. An approximated gradient that can be efficiently calculated is explored to achieve better computational scaling and efficiency. Application to a simple one-dimensional model system from the previous literature confirms the correctness of the method developed in this manuscript. The displaced harmonic model system within the single exciton manifold shows the numerically exact temperature dependence of the coherence and population of the excitonic system. The sampling scheme can be applied to an arbitrary anharmonic environment, such as multichromophoric systems embedded in the protein complex. The result of this study is expected to stimulate further development of real time propagation methods that satisfy the detailed balance condition for exciton populations.
Phase behavior of parallel cut spheres. Monte Carlo and integral equation results
NASA Astrophysics Data System (ADS)
Azzouz, H.; Caillol, J. M.; Levesque, D.; Weis, J. J.
1992-03-01
Monte Carlo simulations of a system of 2500 parallel cut spheres of thickness L/D=0.1 give evidence for a phase transition, at packing fraction ?˜0.40, from the low density nematic phase to a smectic phase. No tendency to formation of columnar ordering is observed up to densities as high as ?=0.60. This behavior contrasts with that of freely rotating cut spheres for which the sequence of stable phases has been identified as isotropic-nematic-columnar-solid [D. Frenkel, Liquid Cryst. 5, 929 (1989)]. For the present system of highly anisotropic molecules the slow convergence of the expansion of correlation functions on rotational invariants precludes quantitative comparison between integral equation theory and simulation results.
Path integral Monte Carlo simulations for rigid rotors and their application to water
NASA Astrophysics Data System (ADS)
Noya, Eva G.; Sesé, Luis M.; Ramírez, Rafael; McBride, Carl; Conde, Maria M.; Vega, Carlos
2011-01-01
In this work the path integral formulation for rigid rotors, proposed by M\\"user and Berne [Phys. Rev. Lett. {\\bf 77}, 2638 (1996)], is described in detail. It is shown how this formulation can be used to perform Monte Carlo simulations of water. Our numerical results show that whereas some properties of water can be accurately reproduced using classical simulations with an empirical potential which, implicitly, includes quantum effects, other properties can only be described quantitatively when quantum effects are explicitly incorporated. In particular, quantum effects are extremely relevant when it comes to describing the equation of state of the ice phases at low temperatures, the structure of the ices at low temperatures, and the heat capacity of both liquid water and the ice phases. They also play a minor role in the relative stability of the ice phases.
Path integral Monte Carlo study of CO2 solvation in 4He clusters
NASA Astrophysics Data System (ADS)
Li, Zheng; Wang, Lecheng; Ran, Hong; Xie, Daiqian; Blinov, N.; Roy, P.-N.; Guo, Hua
2008-06-01
We present a finite temperature quantum mechanical study of the dynamical and structural properties of small 4HeN-CO2 clusters (N<=17) using a path integral Monte Carlo (PIMC) method. The simulations were based on a He-CO2 interaction potential with explicit dependence on the asymmetric stretch of the CO2 molecule obtained at the CCSD(T) level. The shift of the CO2 antisymmetric stretching (?3) band origin and effective rotational constant were calculated as a function of the cluster size. In excellent agreement with experimental observations, the CO2 vibrational band origin shifts and rotational constant show a turnaround near N=5, corresponding to a donut structure with the He atoms in equatorial positions of the linear dopant molecule.
Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Warm Dense Matter
NASA Astrophysics Data System (ADS)
Militzer, Burkhard; Driver, Kevin
2011-10-01
We analyze the applicability of two first-principles simulation techniques, path integral Monte Carlo (PIMC) and density functional molecular dynamics (DFT-MD), to study the regime of warm dense matter. We discuss the advantages as well as the limitations of each method and propose directions for future development. Results for dense, liquid helium, where both methods have been applied, demonstrate the range of each method's applicability. Comparison of the equations of state from simulations with analytical theories and free energy models show that DFT is useful for temperatures below 100000 K and then PIMC provides accurate results for all higher temperatures. We characterize the structure of the liquid in terms of pair correlation functions and study the closure of the band gap with increasing density and temperature. Finally, we discuss simulations of heavier elements and demonstrate the reliability are both methods in such cases with preliminary results.
Path Integral Monte Carlo Study of the Electrical Polarizability of Dimerized Hydrogen Chains
NASA Astrophysics Data System (ADS)
Sanger, Mark; Shumway, John
2007-10-01
Density functional theory is a powerful technique for obtaining ab initio properties of molecules. However, the commonly used techniques have well known weaknesses, especially when computing polarizabilites or band gaps. We have developed a new Quantum Monte Carlo(QMC) technique for calculating static polarizability of molecules using current-current correlation functions in imaginary-time path integrals. The method is applicable to isolated molecules as well as periodic structures. We present the successfull results obtained from simulating the polarizability of dimerized chains of hydrogen atoms at T=300K for both open and periodic boundary conditions. We find excellent agreement with high accuracy quantum chemistry estimates, with a very modest order(N^3) scaling with system size and easy accommodation of periodic boundary conditions.
Localization of acoustic polarons at low temperatures: A path-integral Monte Carlo approach
NASA Astrophysics Data System (ADS)
Fantoni, Riccardo
2012-10-01
We calculate the low-temperature properties of an acoustic polaron in three dimensions in thermal equilibrium at a given temperature using a specialized path-integral Monte Carlo method. In particular we find numerical evidence that the chosen Hamiltonian for the acoustic polaron describes a phase transition from a localized state to an unlocalized state for the electron as the phonon-electron coupling constant decreases. The phase transition manifests itself with a jump discontinuity in the potential energy as a function of the coupling constant. In the weak coupling regime the electron is in an extended state whereas in the strong coupling regime it is found in a self-trapped state.
Finite Size Effect in Path Integral Monte Carlo Simulations of 4 He Systems
NASA Astrophysics Data System (ADS)
Zhao, Xing-Wen; Cheng, Xin-Lu
2008-10-01
Path integral Monte Carlo (PIMC) simulations are a powerful computational method to study interacting quantum systems at finite temperatures. In this work, PIMC has been applied to study the finite size effect of the simulated systems of 4 He. We determine the energy as a function of temperature at saturated-vapor-pressure (SVP) conditions in the temperature range of T ? [1.0 K,4.0 K], and the equation of state (EOS) in the ground state for systems consisted of 32, 64 and 128 4 He atoms, respectively. We find that the energy at SVP is influenced significantly by the size of the simulated system in the temperature range of T ? [2.1 K, 3.0 K] and the larger the system is, the better results are obtained in comparison with the experimental values; while the EOS appeared to be unrelated to it.
WORM ALGORITHM PATH INTEGRAL MONTE CARLO APPLIED TO THE 3He-4He II SANDWICH SYSTEM
NASA Astrophysics Data System (ADS)
Al-Oqali, Amer; Sakhel, Asaad R.; Ghassib, Humam B.; Sakhel, Roger R.
2012-12-01
We present a numerical investigation of the thermal and structural properties of the 3He-4He sandwich system adsorbed on a graphite substrate using the worm algorithm path integral Monte Carlo (WAPIMC) method [M. Boninsegni, N. Prokof'ev and B. Svistunov, Phys. Rev. E74, 036701 (2006)]. For this purpose, we have modified a previously written WAPIMC code originally adapted for 4He on graphite, by including the second 3He-component. To describe the fermions, a temperature-dependent statistical potential has been used. This has proven very effective. The WAPIMC calculations have been conducted in the millikelvin temperature regime. However, because of the heavy computations involved, only 30, 40 and 50 mK have been considered for the time being. The pair correlations, Matsubara Green's function, structure factor, and density profiles have been explored at these temperatures.
Comparisons of Different Particle-Chain Methods for Path Integral Monte Carlo Methods
NASA Astrophysics Data System (ADS)
Reese, Terrence; Miller, Bruce
2007-10-01
In previous work we have used Path Integral Monte Carlo methods to simulate a Positronium atom in a Lennard-Jones fluid. Trial positions are created for sub-chains of particles on the polymer chain to allow for proper exploration of the configuration space. Different methods can be used to determine how the different chains are selected. In this report we compare the results from simulations of Positronium in Xenon at 300 and 340K using our leap frog method and another method where the selection of the sub-chains for trial movements is done randomly. The results indicate that a random selection of sub-chains leads to more accurate simulation results at higher densities.
Platform technologies for hybrid optoelectronic integration and packaging
NASA Astrophysics Data System (ADS)
Datta, Madhumita
In order to bring fiber-optics closer to individual home and business services, the optical network components have to be inexpensive and reliable. Integration and packaging of optoelectronic devices holds the key to high-volume low-cost component manufacturing. The goal of this dissertation is to propose, study, and demonstrate various ways to integrate optoelectronic devices on a packaging platform to implement cost-effective, functional optical modules. Two types of hybrid integration techniques have been proposed: flip-chip solder bump bonding for high-density two-dimensional array packaging of surface-emitting devices, and solder preform bonding for fiber-coupled edge-emitting semiconductor devices. For flip-chip solder bump bonding, we developed a simple, inexpensive remetallization process called "electroless plating", which converts the aluminum bond pads of foundry-made complementary metal oxide semiconductor (CMOS) chips into solder-bondable and wire-bondable gold surfaces. We have applied for a patent on this remetallization technique. For fiber-pigtailed edge-emitting laser modules, we have studied the coupling characteristics of different types of lensed single-mode fibers including semispherically lensed fiber, cylindrically lensed fiber and conically lensed fiber. We have experimentally demonstrated 66% coupling efficiency with semispherically lensed fiber and 50% efficiency with conically lensed fibers. We have proposed and designed a packaging platform on which lensed fibers can be actively aligned to a laser and solder-attached reliably to the platform so that the alignment is retained. We have designed thin-film nichrome heaters on fused quartz platforms as local heat source to facilitate on-board solder alignment and attachment of fiber. The thermal performance of the heaters was simulated using finite element analysis tool ANSYS prior to fabrication. Using the heater's reworkability advantage, we have estimated the shift of the fiber due to solder shrinkage and introduced a pre-correction in the alignment process to restore optimum coupling efficiency close to 50% with conically lensed fibers. We have applied for a patent on this unique active alignment method through the University of Maryland's Technology Commercialization Office. Although we have mostly concentrated on active alignment platforms, we have proposed the idea of combining the passive alignment advantages of silicon optical benches to the on-board heater-assisted active alignment technique. This passive-active alignment process has the potential of cost-effective array packaging of edge-emitting devices.
Fermionic path-integral Monte Carlo results for the uniform electron gas at finite temperature.
Filinov, V S; Fortov, V E; Bonitz, M; Moldabekov, Zh
2015-03-01
The uniform electron gas (UEG) at finite temperature has recently attracted substantial interest due to the experimental progress in the field of warm dense matter. To explain the experimental data, accurate theoretical models for high-density plasmas are needed that depend crucially on the quality of the thermodynamic properties of the quantum degenerate nonideal electrons and of the treatment of their interaction with the positive background. Recent fixed-node path-integral Monte Carlo (RPIMC) data are believed to be the most accurate for the UEG at finite temperature, but they become questionable at high degeneracy when the Brueckner parameter rs=a/aB--the ratio of the mean interparticle distance to the Bohr radius--approaches 1. The validity range of these simulations and their predictive capabilities for the UEG are presently unknown. This is due to the unknown quality of the used fixed nodes and of the finite-size scaling from N=33 simulated particles (per spin projection) to the macroscopic limit. To analyze these questions, we present alternative direct fermionic path integral Monte Carlo (DPIMC) simulations that are independent from RPIMC. Our simulations take into account quantum effects not only in the electron system but also in their interaction with the uniform positive background. Also, we use substantially larger particle numbers (up to three times more) and perform an extrapolation to the macroscopic limit. We observe very good agreement with RPIMC, for the polarized electron gas, up to moderate densities around rs=4, and larger deviations for the unpolarized case, for low temperatures. For higher densities (high electron degeneracy), rs?1.5, both RPIMC and DPIMC are problematic due to the increased fermion sign problem. PMID:25871225
Dunn, K. L.; Wilson, P. P. H. [Department of Engineering Physics, University of Wisconsin - Madison, 1500 Engineering Drive, Madison, WI 53706 (United States)
2013-07-01
A new Monte Carlo mesh tally based on a Kernel Density Estimator (KDE) approach using integrated particle tracks is presented. We first derive the KDE integral-track estimator and present a brief overview of its implementation as an alternative to the MCNP fmesh tally. To facilitate a valid quantitative comparison between these two tallies for verification purposes, there are two key issues that must be addressed. The first of these issues involves selecting a good data transfer method to convert the nodal-based KDE results into their cell-averaged equivalents (or vice versa with the cell-averaged MCNP results). The second involves choosing an appropriate resolution of the mesh, since if it is too coarse this can introduce significant errors into the reference MCNP solution. After discussing both of these issues in some detail, we present the results of a convergence analysis that shows the KDE integral-track and MCNP fmesh tallies are indeed capable of producing equivalent results for some simple 3D transport problems. In all cases considered, there was clear convergence from the KDE results to the reference MCNP results as the number of particle histories was increased. (authors)
NASA Astrophysics Data System (ADS)
Youquan, Jia; Jinan, Xie; Yinyan, Wang
1988-11-01
The paper describes a hybrid experimental and numerical method of Moiré Interferometry and the boundary-integral-element method. The interference patterns used for the evaluation of the displacement vector are obtained by Moiré Interferometry. The boundary displacements obtained experimentally are conveniently used for the calculation of the stress intensity factor in the body by the boundary-integral-method. Some examples bear witness to the effectiveness and accuracy of the hybrid technique.
Radiation Transport for Explosive Outflows: A Multigroup Hybrid Monte Carlo Method
NASA Astrophysics Data System (ADS)
Wollaeger, Ryan T.; van Rossum, Daniel R.; Graziani, Carlo; Couch, Sean M.; Jordan, George C., IV; Lamb, Donald Q.; Moses, Gregory A.
2013-12-01
We explore Implicit Monte Carlo (IMC) and discrete diffusion Monte Carlo (DDMC) for radiation transport in high-velocity outflows with structured opacity. The IMC method is a stochastic computational technique for nonlinear radiation transport. IMC is partially implicit in time and may suffer in efficiency when tracking MC particles through optically thick materials. DDMC accelerates IMC in diffusive domains. Abdikamalov extended IMC and DDMC to multigroup, velocity-dependent transport with the intent of modeling neutrino dynamics in core-collapse supernovae. Densmore has also formulated a multifrequency extension to the originally gray DDMC method. We rigorously formulate IMC and DDMC over a high-velocity Lagrangian grid for possible application to photon transport in the post-explosion phase of Type Ia supernovae. This formulation includes an analysis that yields an additional factor in the standard IMC-to-DDMC spatial interface condition. To our knowledge the new boundary condition is distinct from others presented in prior DDMC literature. The method is suitable for a variety of opacity distributions and may be applied to semi-relativistic radiation transport in simple fluids and geometries. Additionally, we test the code, called SuperNu, using an analytic solution having static material, as well as with a manufactured solution for moving material with structured opacities. Finally, we demonstrate with a simple source and 10 group logarithmic wavelength grid that IMC-DDMC performs better than pure IMC in terms of accuracy and speed when there are large disparities between the magnitudes of opacities in adjacent groups. We also present and test our implementation of the new boundary condition.
An integrated software system for hybrid flight simulation: The boeing hybrid simulator
E. F. Reed; R. P. Schuh; E. Missall
1966-01-01
The Boeing Hybrid Simulator is a general-purpose hybrid computer designed to provide a laboratory for the development of hybrid methods of solving a variety of aero-space problems as well as to support large-scale simulations. The first such simulation is a Flight Simulation Program which provides both a three-degrees-of-freedom missile performance analysis tool and a six-degrees-of-freedom missile subsystem design analysis tool.
Streamline Integration using MPI-Hybrid Parallelism on a Large Multi-Core Architecture
Camp, David; Garth, Christoph; Childs, Hank; Pugmire, Dave; Joy, Kenneth I.
2010-11-01
Streamline computation in a very large vector field data set represents a significant challenge due to the non-local and datadependentnature of streamline integration. In this paper, we conduct a study of the performance characteristics of hybrid parallel programmingand execution as applied to streamline integration on a large, multicore platform. With multi-core processors now prevalent in clustersand supercomputers, there is a need to understand the impact of these hybrid systems in order to make the best implementation choice.We use two MPI-based distribution approaches based on established parallelization paradigms, parallelize-over-seeds and parallelize-overblocks,and present a novel MPI-hybrid algorithm for each approach to compute streamlines. Our findings indicate that the work sharing betweencores in the proposed MPI-hybrid parallel implementation results in much improved performance and consumes less communication andI/O bandwidth than a traditional, non-hybrid distributed implementation.
Boyer, Edmond
Toward Optimal Stratification for Stratified Monte-Carlo Integration Alexandra Carpentier a, the more refined the stratification, the more difficult it is to adjust the allocation of the samples to the stratification, i.e. sample more points where the noise or variations of the function are larger. We provide
Shimkin, Nahum
3 Variance Reduction Methods, I We return to the problem of Monte-Carlo integration, namely approaches. 3.1 Monitoring the Estimation Error Before going into variance reduction, let us discuss briefly = Var(^N ) = · · · = 1 N Var(H(X)) . (Note that the MSE and variance are the same here since
Integrated graphene/nanoparticle hybrids for biological and electronic applications
NASA Astrophysics Data System (ADS)
Nguyen, Kim Truc; Zhao, Yanli
2014-05-01
The development of novel graphene/nanoparticle hybrid materials is currently the subject of tremendous research interest. The intrinsic exceptional assets of both graphene (including graphene oxide and reduced graphene oxide) and nanoparticles render their hybrid materials synergic properties that can be useful in various applications. In this feature review, we highlight recent developments in graphene/nanoparticle hybrids and their promising potential in electronic and biological applications. First, the latest advances in synthetic methods for the preparation of the graphene/nanoparticle hybrids are introduced, with the emphasis on approaches to (1) decorate nanoparticles onto two-dimensional graphene and (2) wrap nanoparticles with graphene sheets. The pros and cons of large-scale synthesis are also discussed. Then, the state-of-the-art of graphene/nanoparticle hybrids in electronic and biological applications is reviewed. For electronic applications, we focus on the advantages of using these hybrids in transparent conducting films, as well as energy harvesting and storage. Biological applications, electrochemical biosensing, bioimaging, and drug delivery using the hybrids are showcased. Finally, the future research prospects and challenges in this rapidly developing area are discussed.
[The economic solution for integrating radiology and surgery: hybrid OR].
Freitag, T; Langer, S
2012-10-01
Currently, interventional (angiographically-guided) therapies have become more and more important in cardiovascular medicine. Hybrid procedures in hybrid operating rooms (ORs) have now become major topics at national and international meetings. A few hospitals have already implemented the project "hybrid OR", in some institutions the system is still in the planning stage. The aim of our article is to present the hospital management point of view, and thus, to focus on the economic and logistic issues from planning through to implementation. PMID:23136104
McSKY: A hybrid Monte-Carlo lime-beam code for shielded gamma skyshine calculations
Shultis, J.K.; Faw, R.E.; Stedry, M.H. [Kansas State Univ., Manhattan, KS (United States). Dept. of Nuclear Engineering; Hall, W. [Kansas State Univ., Manhattan, KS (United States)
1994-07-01
McSKY evaluates skyshine dose from an isotropic, monoenergetic, point photon source collimated into either a vertical cone or a vertical structure with an N-sided polygon cross section. The code assumes an overhead shield of two materials, through the user can specify zero shield thickness for an unshielded calculation. The code uses a Monte-Carlo algorithm to evaluate transport through source shields and the integral line source to describe photon transport through the atmosphere. The source energy must be between 0.02 and 100 MeV. For heavily shielded sources with energies above 20 MeV, McSKY results must be used cautiously, especially at detector locations near the source.
Advanced Monte Carlo Methods: General Principles of the Monte
Mascagni, Michael
Advanced Monte Carlo Methods: General Principles of the Monte Carlo Method Prof. Dr. Michael of Monte CarloProf. Dr. Michael Mascagni: Advanced Monte Carlo Methods Slide 2 of 61 Numerical Integration: The Canonical Monte Carlo Application Numerical integration is a simple problem to explain and thoroughly
Two-step hybrid methods adapted to the numerical integration of perturbed oscillators
Hans Van de Vyver
2006-01-01
Two-step hybrid methods specially adapted to the numerical integration of perturbed oscillators are obtained. The formulation of the methods is based on a refinement of classical Taylor expansions due to Scheifele [{\\\\em Z. Angew. Math. Phys.}, {\\\\bf 22}, 186--210 (1971)]. The key property is that those algorithms are able to integrate exactly harmonic oscillators with frequency $\\\\omega$ and that, for
Nobuhide Fujioka; Tao Chu; Masashige Ishizaka
2010-01-01
Silicon photonics is expected to reduce size and cost of photonic devices and realize large scale photonic integrated circuits for telecom and datacom applications. In this paper, we demonstrate a compact wavelength tunable laser module using hybrid integrated semiconductor optical amplifier and silicon waveguide resonators. The power consumption of the laser module is 1 W to obtain +8 dBm fiber
Hybrid Clustering by Integrating Text and Citation based Graphs in Journal Database Analysis
Hybrid Clustering by Integrating Text and Citation based Graphs in Journal Database Analysis Xinhai with the crite- rion of maximizing the Average Normalized Mutual Infor- mation(ANMI). The methods are applied to obtain struc- tural mapping of large scale Web of Science (WoS) journal database by integrating attribute
Monte Carlo solution of the volume-integral equation of electromagnetic scattering
NASA Astrophysics Data System (ADS)
Peltoniemi, J.; Muinonen, K.
2014-07-01
Electromagnetic scattering is often the main physical process to be understood when interpreting the observations of asteroids, comets, and meteors. Modeling the scattering faces still many problems, and one needs to assess several different cases: multiple scattering and shadowing by the rough surface, multiple scattering inside a surface element, and single scattering by a small object. Our specific goal is to extend the electromagnetic techniques to larger and more complicated objects, and derive approximations taking into account the most important effects of waves. Here we experiment with Monte Carlo techniques: can they provide something new to solving the scattering problems? The electromagnetic wave equation in the presence of a scatterer of volume V and refractive index m, with an incident wave EE_0, including boundary conditions and the scattering condition at infinity, can be presented in the form of an integral equation EE(rr)(1+suski(rr) Q(?))-int_{V-V_?}ddrr' GG(rr-rr')suski(rr')EE(rr') =EE_0, where suski(rr)=m(rr)^2-1, Q(?)=-1/3+{cal O}(?^2)+{O'}(m^2?^2), {O}, and {O'} are some second- and higher-order corrections for the finite-size volume V_? of radius ? around the singularity and GG is the dyadic Green's function of the form GG(RR)={exp(im kR)}/{4? R}[unittensor(1+{im}/{R}-{1}/{R^2})-RRRR(1+{3im}/{R}-{3}/{R^2})]. In general, this is solved by extending the internal field in terms of some simple basis functions, e.g., plane or spherical waves or a cubic grid, approximating the integrals in a clever way, and determining the goodness of the solution somehow, e.g., moments or least square. Whatever the choice, the solution usually converges nicely towards a correct enough solution when the scatterer is small and simple, and diverges when the scatterer becomes too complicated. With certain methods, one can reach larger scatterers faster, but the memory and CPU needs can be huge. Until today, all successful solutions are based on more or less regular quadratures. Because of the oscillating singularity of the Green's function, the quadrature must match exactly the canceling patterns of the integrand, and any improper quadrature leads to large errors. Monte Carlo based integration appears thus a very bad choice, but we take the challenge, and formulate the integration applying a three-finger rule to catch the singularity. Our other selections are the least-squares technique and plane-wave basis, though both can be freely and easily changed. The singularity is treated fully numerically, and the radius ? is assumed so small that the correction terms do not contribute. Any other choice only worsens the accuracy, without a significant gain in speed. As with any other technique, we can solve small spheres of size x<5/|m| within an hour of processor time with about 1% accuracy for a large range of refractive indices. In speed, this technique does not compete with faster techniques such as ADDA, but in some random cases the accuracy can be even better (probably due to sub-optimal singularity formula in ADDA -- applying numerical integration also there could probably make ADDA winner in all the cases). We continue towards more complicated cases and multiple scattering to see, if some further improvements can be made.
Streamline Integration Using MPI-Hybrid Parallelism on a Large Multicore Architecture
Garth, Christoph [unknown
2011-01-01
Streamline computation in a very large vector field data set represents a significant challenge due to the nonlocal and data-dependent nature of streamline integration. In this paper, we conduct a study of the performance characteristics of hybrid parallel programming and execution as applied to streamline integration on a large, multicore platform. With multicore processors now prevalent in clusters and supercomputers, there is a need to understand the impact of these hybrid systems in order to make the best implementation choice. We use two MPI-based distribution approaches based on established parallelization paradigms, parallelize over seeds and parallelize over blocks, and present a novel MPI-hybrid algorithm for each approach to compute streamlines. Our findings indicate that the work sharing between cores in the proposed MPI-hybrid parallel implementation results in much improved performance and consumes less communication and I/O bandwidth than a traditional, nonhybrid distributed implementation.
Enhancing CMOS Using Nanoelectronic Devices: A Perspective on Hybrid Integrated Systems
David S. Ricketts; James A. Bain; Yi Luo; R. D. Blanton; Kenneth Mai; Gary K. Fedder
2010-01-01
In this paper, we present a vision for the cointegration of deeply scaled complementary metal-oxide-semiconductor (CMOS) and emerging nanoelectronic devices into CMOS-hybrid systems. These hybrid systems will create new functionality, modality and add value to existing CMOS integrated circuits. We describe several new nanoelectronic devices which may enable new dimensions to traditional CMOS circuits and systems that build on CMOS
ZHANG, HUAN; LI, TAO; WU, GUANJI; MA, FENG
2014-01-01
Coronary artery disease (CAD) is the most common type of cardiovascular disease and leading cause of mortality worldwide. Microarray technology for gene expression analysis has facilitated the identification of the molecular mechanism that underlies the pathogenesis of CAD. Previous studies have primarily used variance or regression analysis, without considering array specific factors. Thus, the aim of the present study was to investigate the mechanism of CAD using partial least squares (PLS)-based analysis, which was integrated with the Monte Carlo technique. Microarray analysis was performed with a data set of 110 CAD patients and 111 controls obtained from the Gene Expression Omnibus database. A total of 390 dysregulated genes were acquired. Significantly increased representations of dysregulated genes in Gene Ontology items, including transforming growth factor ?-activated receptor activity and acyl-CoA oxidase activity, were identified. Network analysis revealed three hub genes with a degree of >10, including ESR1, ITGA4 and ARRB2. The results of the present study provide novel information on the gene expression signatures of CAD patients and offer further theoretical support for future therapeutic study. PMID:24940402
Path integral Monte Carlo and density functional molecular dynamics simulations of hot, dense helium
NASA Astrophysics Data System (ADS)
Militzer, B.
2009-04-01
Two first-principles simulation techniques, path integral Monte Carlo (PIMC) and density functional molecular dynamics (DFT-MD), are applied to study hot, dense helium in the density-temperature range of 0.387-5.35gcm-3 and 500K-1.28×108K . One coherent equation of state is derived by combining DFT-MD data at lower temperatures with PIMC results at higher temperatures. Good agreement between both techniques is found in an intermediate-temperature range. For the highest temperatures, the PIMC results converge to the Debye-Hückel limiting law. In order to derive the entropy, a thermodynamically consistent free-energy fit is used that reproduces the internal energies and pressure derived from the first-principles simulations. The equation of state is presented in the form of a table as well as a fit and is compared with different free-energy models. Pair-correlation functions and the electronic density of states are discussed. Shock Hugoniot curves are compared with recent laser shock-wave experiments.
Path integral Monte Carlo study of quantum-hard sphere solids
NASA Astrophysics Data System (ADS)
Sesé, Luis M.
2013-07-01
A path integral study of the fcc, hcp, and bcc quantum hard-sphere solids is presented. Ranges of densities within the interval of reduced de Broglie wavelengths 0.2 ? ? _B^* ? 0.8 have been analyzed using Monte Carlo simulations with Cao-Berne propagator. Energies, pressures, and structural quantities (pair radial correlation functions, centroid structure factors, and Steinhardt order parameters) have been computed. Also, applications of the Einstein crystal technique [L. M. Sesé, J. Chem. Phys. 126, 164508 (2007)] have been made to compute the free energies of the fcc and hcp solids. Some technical points related to the latter technique are discussed, and it is shown that these calculations produce consistent results with increasing sample sizes. The fluid-solid (fcc and hcp) equilibria have been studied, thus completing prior work by this author on the fluid-fcc equilibrium. Within the accuracy attained no significant differences between the relative stabilities of the fcc and hcp lattices have been detected. The bcc case stands apart from the other two lattices, as the simulations lead either to irregular lattices (two types) that keep some traces of bcc-memory, or to spontaneous transitions to hcp-like lattices. The latter transitions make manifestly clear the potential repercussions that the quantum hard-sphere behavior can have on solid-solid equilibria at low temperatures in real systems (e.g., helium).
Path-integral ground-state Monte Carlo study of two-dimensional solid He4
NASA Astrophysics Data System (ADS)
Vitali, E.; Rossi, M.; Tramonto, F.; Galli, D. E.; Reatto, L.
2008-05-01
We have studied a two-dimensional (2D) triangular commensurate crystal of He4 with the exact T=0K path-integral ground-state (PIGS) Monte Carlo method. We have projected onto the true ground state two qualitatively different wave functions, a Jastrow-Nosanow wave function and a translationally invariant shadow wave function. The PIGS method passes this hard test of validity and applicability by obtaining the convergence to the same properties, both the diagonal ones as well as the off-diagonal one-body density matrix ?1 . Thus, the commensurate 2D He4 crystal at T=0K is exactly solved, we find no Bose-Einstein condensation (BEC), and ?1 shows a dominant exponential decay in the large distance range. The structure found in ?1 is due to virtual vacancy-interstitial pairs and this shows up in the momentum distribution. Our result indicates that BEC in 2D solid He4 can only arise in the presence of some kind of disorder, either intrinsic or extrinsic.
A path-integral Monte Carlo study of a small cluster: The Ar trimer
NASA Astrophysics Data System (ADS)
Pérez de Tudela, R.; Márquez-Mijares, M.; González-Lezana, T.; Roncero, O.; Miret-Artés, S.; Delgado-Barrio, G.; Villarreal, P.
2010-06-01
The Ar3 system has been studied between T =0 K and T =40 K by means of a path-integral Monte Carlo (PIMC) method. The behavior of the average energy in terms of the temperature has been explained by comparison with results obtained with the thermal averaged rovibrational spectra estimated via: (i) a quantum mechanical method based on distributed Gaussian functions for the interparticle distances and (ii) an analytical model which precisely accounts for the participation of the dissociative continua Ar2+Ar and Ar+Ar+Ar. Beyond T ˜20 K, the system explores floppier configurations than the rigid equilateral geometry, as linear and Ar-Ar2-like arrangements, and fragmentates around T ˜40 K. A careful investigation of the specific heat in terms of a confining radius in the PIMC calculation seems to discard a proper phase transition as in larger clusters, in apparent contradiction with previous reports of precise values for a liquid-gas transition. The onset of this noticeable change in the dynamics of the trimer occurs, however, at a remarkably low value of the temperature in comparison with Arn systems formed with more Ar atoms. Quantum mechanical effects are found of relevance at T ?15 K, with both energies and radial distributions obtained with a quantum PIMC deviating from the corresponding classical results, thus precluding exclusively classical approaches for a precise description of the system at this low temperature range.
Dilute Bose gas with correlated disorder: a path integral Monte Carlo study
NASA Astrophysics Data System (ADS)
Pilati, S.; Giorgini, S.; Modugno, M.; Prokof'ev, N.
2010-07-01
We investigate the thermodynamic properties of a dilute Bose gas in a correlated random potential using exact path integral Monte Carlo methods. The study is carried out in continuous space and disorder is produced in the simulations by a three-dimensional (3D) speckle pattern with tunable intensity and correlation length. We calculate the shift of the superfluid transition temperature due to disorder and we highlight the role of quantum localization by comparing the critical chemical potential with the classical percolation threshold. The equation of state of the gas is determined in the regime of strong disorder, where superfluidity is suppressed and the normal phase exists down to very low temperatures. We find a T2 dependence of the energy in agreement with the expected behavior in the Bose glass phase. We also discuss the major role played by the disorder correlation length and we make contact with a Hartree-Fock mean-field approach that holds if the correlation length is very large. The density profiles are analyzed as a function of temperature and interaction strength. Effects of localization and the depletion of the order parameter are emphasized in the comparison between local condensate and total density. At very low temperature, we find that the energy and the particle distribution of the gas are very well described by the T=0 Gross-Pitaevskii theory, even in the regime of very strong disorder.
Path-integral Monte Carlo Study on Weakly-Coupled ^4He Superfluids
NASA Astrophysics Data System (ADS)
Kwon, Yongkyung; Whaley, K. Birgitta
2010-03-01
We have performed path-integral Monte Carlo calculations to analyze the dynamics of flow between two weakly-coupled ^4He superfluids, employing a system of ^4He atoms inside a tube whose diameter and length are an order of a few nanometers. The two ^4He superfluids separated by a wall in the middle of the tube are connected to each other through an array of apertures created in the wall. For the case of a single aperture it is found that the local suppression of superfluidity near the wall is greatly dependent on the size of the aperture hole. The superfluid fraction computed through the local decomposition of the winding number estimator is reduced to about 30% at T=0.6 K near the aperture hole with the diameter of ˜ 4 while it is hardly suppressed at all when the diameter of the hole is as large as 8 å. For the case of an array of apertures, we investigate the effects of aperture-aperture coupling on the local superfluidity by varying the inter-aperture distance. The velocity-velocity correlation function is computed to analyze the correlation among the superflows through the different apertures. These results are discussed in relation with the synchronous phase slippages observed in recent experiments of Packard et al. for an array of apertures connecting two reservoirs of superfluid ^4He.
4 He Adsorption on a Single Graphene Sheet: Path-integral Monte Carlo Study
NASA Astrophysics Data System (ADS)
Kwon, Yongkyung; Ceperley, David
2011-03-01
We have performed path-integral Monte Carlo calculations to study 4He adsorption on a single graphene sheet, where the 4He-substrate interaction is described by the sum of the helium-carbon pair potentials. Among those proposed to account for helium scattering data on the graphite surface, we employ three different types of the inter-atomic pair potentials; a spherical 6-12 potential, an anisotropic 6-12 potential, and an anisotropic Yukawa-6 potential. Regardless of the choice of the pair potential, a first 4He monolayer is found to show the C1 / 3 commensurate structure at a surface density of 0.0636 Å-2 and to go through the domain wall phases for densities above the commensurate one before crystallizing into an incommensurate triangular solid. Below the commensurate density, however, the low-temperature phase of this helium adlayer varies depending on the choice of the 4He-substrate interaction. The calculation based on the spherical pair potentials suggests a superfluid liquid phase at lower densities while incorporation of anisotropy into the helium-carbon pair potential results in a low-density state of a solid with clustered vacancies. Finally we observe van der Waals correlation between the upper monolayer and the one below the graphene sheet. The effects of this interlayer correlation on a possible formation of stable vacancies will be discussed.
4He adsorption on a single graphene sheet: Path-integral Monte Carlo study
NASA Astrophysics Data System (ADS)
Kwon, Yongkyung; Ceperley, David M.
2012-06-01
We have performed path-integral Monte Carlo calculations to study 4He adsorption on a single graphene sheet. The 4He-substrate interaction was assumed to be a pairwise sum of the helium-carbon potentials constructed by Carlos and Cole to fit helium scattering data from a graphite surface. We employed both an anisotropic 6-12 Lennard-Jones potential and a spherical 6-12 potential. For both potentials, the first 4He layer has the C1/3 commensurate structure at a surface density of 0.0636 Å-2. Vacancy states created in the C1/3 commensurate solid, however, behave differently depending on the 4He-substrate interaction: a cluster of localized vacancies are formed with the fully anisotropic 6-12 pair potentials while mobile vacancies are found to induce finite superfluid fractions with the substrate potential based on only the isotropic parts of the inter-atomic pair potentials. For the second helium layer we find that exchange among 4He adatoms results in quantum melting of a C7/12 commensurate structure, which is registered to a first-layer triangular solid. The possible stabilization of this commensurate structure with the addition of 3He impurities is discussed.
Zhang, Wenli; Muck-Hausl, Martin; Wang, Jichang; Sun, Chuanbo; Gebbing, Maren; Miskey, Csaba; Ivics, Zoltan; Izsvak, Zsuzsanna; Ehrhardt, Anja
2013-01-01
We recently developed adenovirus/transposase hybrid-vectors utilizing the previously described hyperactive Sleeping Beauty (SB) transposase HSB5 for somatic integration and we could show stabilized transgene expression in mice and a canine model for hemophilia B. However, the safety profile of these hybrid-vectors with respect to vector dose and genotoxicity remains to be investigated. Herein, we evaluated this hybrid-vector system in C57Bl/6 mice with escalating vector dose settings. We found that in all mice which received the hyperactive SB transposase, transgene expression levels were stabilized in a dose-dependent manner and that the highest vector dose was accompanied by fatalities in mice. To analyze potential genotoxic side-effects due to somatic integration into host chromosomes, we performed a genome-wide integration site analysis using linker-mediated PCR (LM-PCR) and linear amplification-mediated PCR (LAM-PCR). Analysis of genomic DNA samples obtained from HSB5 treated female and male mice revealed a total of 1327 unique transposition events. Overall the chromosomal distribution pattern was close-to-random and we observed a random integration profile with respect to integration into gene and non-gene areas. Notably, when using the LM-PCR protocol, 27 extra-chromosomal integration events were identified, most likely caused by transposon excision and subsequent transposition into the delivered adenoviral vector genome. In total, this study provides a careful evaluation of the safety profile of adenovirus/Sleeping Beauty transposase hybrid-vectors. The obtained information will be useful when designing future preclinical studies utilizing hybrid-vectors in small and large animal models. PMID:24124483
Axel Hoefer; Oliver Buss; Maik Hennebach; Michael Schmid; Dieter Porsch
2014-11-12
MOCABA is a combination of Monte Carlo sampling and Bayesian updating algorithms for the prediction of integral functions of nuclear data, such as reactor power distributions or neutron multiplication factors. Similarly to the established Generalized Linear Least Squares (GLLS) methodology, MOCABA offers the capability to utilize integral experimental data to reduce the prior uncertainty of integral observables. The MOCABA approach, however, does not involve any series expansions and, therefore, does not suffer from the breakdown of first-order perturbation theory for large nuclear data uncertainties. This is related to the fact that, in contrast to the GLLS method, the updating mechanism within MOCABA is applied directly to the integral observables without having to "adjust" any nuclear data. A central part of MOCABA is the nuclear data Monte Carlo program NUDUNA, which performs random sampling of nuclear data evaluations according to their covariance information and converts them into libraries for transport code systems like MCNP or SCALE. What is special about MOCABA is that it can be applied to any integral function of nuclear data, and any integral measurement can be taken into account to improve the prediction of an integral observable of interest. In this paper we present two example applications of the MOCABA framework: the prediction of the neutron multiplication factor of a water-moderated PWR fuel assembly based on 21 criticality safety benchmark experiments and the prediction of the power distribution within a toy model reactor containing 100 fuel assemblies.
Murakami, Yohei; Takada, Shoji
2013-01-01
When exact values of model parameters in systems biology are not available from experiments, they need to be inferred so that the resulting simulation reproduces the experimentally known phenomena. For the purpose, Bayesian statistics with Markov chain Monte Carlo (MCMC) is a useful method. Biological experiments are often performed with cell population, and the results are represented by histograms. On another front, experiments sometimes indicate the existence of a specific bifurcation pattern. In this study, to deal with both type of such experimental results and information for parameter inference, we introduced functions to evaluate fitness to both type of experimental results, named quantitative and qualitative fitness measures respectively. We formulated Bayesian formula for those hybrid fitness measures (HFM), and implemented it to MCMC (MCMC-HFM). We tested MCMC-HFM first for a kinetic toy model with a positive feedback. Inferring kinetic parameters mainly related to the positive feedback, we found that MCMC-HFM reliably infer them with both qualitative and quantitative fitness measures. Then, we applied the MCMC-HFM to an apoptosis signal transduction network previously proposed. For kinetic parameters related to implicit positive feedbacks, which are important for bistability and irreversibility of the output, the MCMC-HFM reliably inferred these kinetic parameters. In particular, some kinetic parameters that have the experimental estimates were inferred without these data and the results were consistent with the experiments. Moreover, for some parameters, the mixed use of quantitative and qualitative fitness measures narrowed down the acceptable range of parameters. Taken together, our approach could reliably infer the kinetic parameters of the target systems. PMID:24086320
The importance of hybrid PV-building integration
M. Posnansky; S. Gnos; S. Coonen
1994-01-01
An extensive utilization of photovoltaics for future electricity generation and for hybrid generation of electricity and thermal energy is possible, when PV-panels are designed to become a part of the building envelope itself. Large areas are available, since roofs and facades are perfectly suited for solar energy conversion. TALENTS ENERGY LTD has developed special PV-generators which fulfill at the same
Hybrid Silicon Evanescent Photonic Integrated Circuit John E. Bowersa
Bowers, John
Blvd, SC-12-326, Santa Clara, CA 95054, USA c Intel Corporation, SBI Park Har Hotzvim, Jerusalem, 91031 Santa Barbara, ECE Department, Santa Barbara, CA 93106, USA b Intel Corporation, 2200 Mission College-V active devices and the silicon waveguides. Recently, we demonstrated an electrically pumped hybrid
Ultra-efficient 10 Gb/s hybrid integrated silicon photonic transmitter and receiver.
Zheng, Xuezhe; Patil, Dinesh; Lexau, Jon; Liu, Frankie; Li, Guoliang; Thacker, Hiren; Luo, Ying; Shubin, Ivan; Li, Jieda; Yao, Jin; Dong, Po; Feng, Dazeng; Asghari, Mehdi; Pinguet, Thierry; Mekis, Attila; Amberg, Philip; Dayringer, Michael; Gainsley, Jon; Moghadam, Hesam Fathi; Alon, Elad; Raj, Kannan; Ho, Ron; Cunningham, John E; Krishnamoorthy, Ashok V
2011-03-14
Using low parasitic microsolder bumping, we hybrid integrated efficient photonic devices from different platforms with advanced 40 nm CMOS VLSI circuits to build ultra-low power silicon photonic transmitters and receivers for potential applications in high performance inter/intra-chip interconnects. We used a depletion racetrack ring modulator with improved electro-optic efficiency to allow stepper optical photo lithography for reduced fabrication complexity. Integrated with a low power cascode 2 V CMOS driver, the hybrid silicon photonic transmitter achieved better than 7 dB extinction ratio for 10 Gbps operation with a record low power consumption of 1.35 mW. A received power penalty of about 1 dB was measured for a BER of 10(-12) compared to an off-the-shelf lightwave LiNOb3 transmitter, which comes mostly from the non-perfect extinction ratio. Similarly, a Ge waveguide detector fabricated using 130 nm SOI CMOS process was integrated with low power VLSI circuits using hybrid bonding. The all CMOS hybrid silicon photonic receiver achieved sensitivity of -17 dBm for a BER of 10(-12) at 10 Gbps, consuming an ultra-low power of 3.95 mW (or 395 fJ/bit in energy efficiency). The scalable hybrid integration enables continued photonic device improvements by leveraging advanced CMOS technologies with maximum flexibility, which is critical for developing ultra-low power high performance photonic interconnects for future computing systems. PMID:21445153
Submonolayer molecular hydrogen on graphite: A path-integral Monte Carlo study
NASA Astrophysics Data System (ADS)
Nho, Kwangsik; Manousakis, Efstratios
2002-03-01
We have used path-integral Monte Carlo (PIMC) to simulate molecular hydrogen on graphite at submonolayer coverage. First we use a flat substrate and we study the first layer for various values of the coverage up to layer completion. We found that the first layer has a solid-gas coexistence phase at low densities and a triangular solid phase at and above the equilibrium density ?0=0.0705 Å-2. We also determine that the first layer promotion coverage is at 0.094 Å-2 in agreement with experiment. Second we introduce the full H2-graphite interaction, i.e., we include the effects of substrate corrugations. In this case we carry our PIMC simulations on a variety of systems at and below the 1/3 coverage. We calculate the energy as a function of coverage, contour plots of the molecule probability distribution, the pair distribution function, the static structure function and the specific heat. When the substrate corrugation part of the interaction is included we find that at 1/3 coverage the system is in a (3)×(3) commensurate solid phase. At coverages below that and at low enough temperature the system exists in solid clusters surrounded by vapor. At coverages below a critical density, defining a tricrical point, as the system is heated up these clusters melt into a uniform fluid phase. We find that below the commensurate density and above the tricritical point, as the clusters are heated up, first they undergo a transition into a phase where the vapor phase disappears and a commensurate phase with vacancies arises. This commensurate solid melts at higher temperature into a uniform fluid phase.
Path integral Monte Carlo studies of the H5+/D5+ clusters using ab initio potential surfaces
NASA Astrophysics Data System (ADS)
Barragán, P.; Pérez de Tudela, R.; Prosmiti, R.; Villarreal, P.; Delgado-Barrio, G.
2011-08-01
We report here on classical and path integral Monte Carlo studies for the H5+ cluster and its deuterated counterpart, in order to investigate the floppy nature of its molecular structure due to anharmonic quantum effects. This method relies on the standard harmonic normal mode analysis and has been found to be effective for evaluating thermochemical/ground-state properties of highly anharmonic systems. A full-dimensional recent analytical CCSD(T) potential surface and a novel realistic density functional theory (DFT) 'on the fly'-based potential scheme were employed. Thermal equilibrium energies for H5+ and D5+ are determined from the path integral Monte Carlo (PIMC) calculations. The H5+ and D5+ probability density distributions are also obtained from both classical Monte Carlo and fully converged PIMC calculations, and they show strong spatial delocalization with highly anharmonic character. It was found that, on average, H5+ and D5+ can be described as a proton shared between the two outer almost freely rotating H2/D2 molecules. The implementation of such a combined PIMC/DFT approach to study nuclear quantum fluctuation on the electronic properties of H5+ is discussed, and its extension to larger protonated hydrogen clusters is also proposed.
A New Approach to the Design of Hybrid Lenses for Integrated Optics
Michele A. Forastiere; Giancarlo C. Righini
1999-01-01
The Fresnel lens is one of the most extensively studied components in both classical and integrated optics. This structure is free from axial spherical aberration, but is heavily affected by both off-axis and chromatic aberrations. The latter can be compensated by introducing a refractive component, whose chromatic behavior is the opposite of that of the diffractive lens. This hybrid refractive-diffractive
Remote power delivery for hybrid integrated bio-implantable electrical stimulation system
Venkat R. Gaddam; Jagadish Yernagula; Raghavendra R. Anantha; Satish Kona; Sunitha Kopparthi; A. Chamakura; Pratul K. Ajmera; Ashok Srivastava
2005-01-01
In this work, a remote power delivery system to charge rechargeable batteries that power a Bio-implanted Electrical Stimulation System (BESS) is first described. A loosely coupled inductive transmitter and receiver system has been used to power a bio-implanted gastric pacer. The receiver coil, rechargeable batteries, battery charging chip and the chip containing stimulation circuitry form a hybrid integrated microsystem. A
Lauermann, M.; Weimann, C.; Palmer, R.; Schindler, P. C. [Institute of Photonics and Quantum Electronics, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Koeber, S.; Freude, W., E-mail: christian.koos@kit.edu; Koos, C., E-mail: christian.koos@kit.edu [Institute of Photonics and Quantum Electronics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany and Institute of Microstructure Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen (Germany); Rembe, C. [Polytec GmbH, 76337 Waldbronn (Germany)
2014-05-27
We demonstrate a waveguide-based frequency shifter on the silicon photonic platform, enabling frequency shifts up to 10 GHz. The device is realized by silicon-organic hybrid (SOH) integration. Temporal shaping of the drive signal allows the suppression of spurious side-modes by more than 23 dB.
LOW COST IMPROVEMENTS TO BUILDING INTEGRATED AIR COOLED HYBRID PV-THERMAL SYSTEMS
Y. Tripanagnostopoulos; M. Souliotis
Hybrid PV-Thermal systems can be integrated on building façade and inclined roof, instead of plain PV modules, providing simultaneously electricity and heat. Heat extraction by air circulation is considered a simple PV cooling mode, by which PV electrical efficiency can be kept at a satisfactory level, building undesirable heating can be avoided during summer and space heating of building can
An integrated ant colony optimization algorithm for the hybrid flow shop scheduling problem
Safa Khalouli; Fatima Ghedjati; Abdelaziz Hamzaoui
2009-01-01
This study addresses the multistage hybrid flow shop scheduling problem. The objective of scheduling is to assign each operation to a machine out of the set of eligible machines and to determine the processing operation sequences on the machines so that the makespan is minimized. Hence to solve this NP-hard problem, an integrated ant colony optimization algorithm is proposed. To
Chantana Punlek; Rattanachai Pairintra; Sirinuch Chindaraksa; Somchai Maneewan
2009-01-01
The aim of this research is to make a simulation design for a hybrid PV\\/T assisted desiccant integrated HA-IR drying system (HPIRD) which has two components: a photovoltaic air collector (PVAC), and a desiccant silica gel bed (DB). The PVAC and DB have been improved by fins and different bed shapes for improved performance of the drying system. The designed
HiFi-WiN: Hybrid Integrated Fiber-Wireless Networking for Broadband Metropolitan Area
Kansas, University of
. In this configuration, the fiber optic cables act as "extension cords" between the CO and WAP units, where, and (iii) the fiber capacity is increased due to the use of an analog optical transmission format. DespiteHiFi-WiN: Hybrid Integrated Fiber-Wireless Networking for Broadband Metropolitan Area Access
Hybrid integration of optical and electronic components on a silicon motherboard
C. A. Jones; K. Cooper; M. W. Nield; J. D. Rush; J. V. Collins; I. P. Hall; A. P. McDonna; S. J. Brown
1994-01-01
We have demonstrated silicon motherboard transmitter and receiver modules with planar silica waveguide optical interconnects. In both modules the active optoelectronic components were passively aligned to the silica waveguides, and electronic circuitry was also hybrid integrated. We are now- developing motherboards which include an electrical interconnect layer formed directly on the silicon, in order to overcome the limitations encountered with
Hybrid derivative-free EKF for USBL\\/INS tightly-coupled integration in AUV
Yanrui Geng; Joao Sousa
2010-01-01
This paper presents a novel hybrid derivative-free extended Kalman filter, which takes advantage of both the linear time propagation of the Kalman filter and nonlinear measurement propagation of the derivative-free extended Kalman filter. The proposed filter is very suitable for the tightly coupled integration navigation system which consists of USBL or GPS with INS. The computation burden is reduced sharply
The energy demand of distillation-molecular sieve systems for ethanol recovery/dehydration can be significant, particularly for dilute solutions. An alternative hybrid process integrating vapor stripping (like a beer still) with vapor compression and a vapor permeation membrane s...
An Integrated Optofluidic Platform for DNA Hybridization and Detection
Des Brennan; Paul Lambkin; Eric J. Moore; Paul Galvin
2008-01-01
There has been extensive research into micro total analysis systems (micro-TAS) and lab-on-a-chip research due to the benefits of increased sample throughput, reduced sample consumption, and rapid analysis times. The integration of low-cost fluidic and optical components offers the possibility of complex systems with increased functionality on a single detection platform. For the development of an integrated optofluidic system for
Design of integrated hybrid silicon waveguide optical gyroscope.
Srinivasan, Sudharsanan; Moreira, Renan; Blumenthal, Daniel; Bowers, John E
2014-10-20
We propose and analyze a novel highly integrated optical gyroscope using low loss silicon nitride waveguides. By integrating the active optical components on chip, we show the possibility of reaching a detection limit on the order of 19°/hr/?Hz in an area smaller than 10 cm(2). This study examines a number of parameters, including the dependence of sensitivity on sensor area. PMID:25401532
El-Kady, Maher F; Ihns, Melanie; Li, Mengping; Hwang, Jee Youn; Mousavi, Mir F; Chaney, Lindsay; Lech, Andrew T; Kaner, Richard B
2015-04-01
Supercapacitors now play an important role in the progress of hybrid and electric vehicles, consumer electronics, and military and space applications. There is a growing demand in developing hybrid supercapacitor systems to overcome the energy density limitations of the current generation of carbon-based supercapacitors. Here, we demonstrate 3D high-performance hybrid supercapacitors and microsupercapacitors based on graphene and MnO2 by rationally designing the electrode microstructure and combining active materials with electrolytes that operate at high voltages. This results in hybrid electrodes with ultrahigh volumetric capacitance of over 1,100 F/cm(3). This corresponds to a specific capacitance of the constituent MnO2 of 1,145 F/g, which is close to the theoretical value of 1,380 F/g. The energy density of the full device varies between 22 and 42 Wh/l depending on the device configuration, which is superior to those of commercially available double-layer supercapacitors, pseudocapacitors, lithium-ion capacitors, and hybrid supercapacitors tested under the same conditions and is comparable to that of lead acid batteries. These hybrid supercapacitors use aqueous electrolytes and are assembled in air without the need for expensive "dry rooms" required for building today's supercapacitors. Furthermore, we demonstrate a simple technique for the fabrication of supercapacitor arrays for high-voltage applications. These arrays can be integrated with solar cells for efficient energy harvesting and storage systems. PMID:25831542
Hybrid Lentivirus-transposon Vectors With a Random Integration Profile in Human Cells
Staunstrup, Nicklas H; Moldt, Brian; Mátés, Lajos; Villesen, Palle; Jakobsen, Maria; Ivics, Zoltán; Izsvák, Zsuzsanna; Mikkelsen, Jacob Giehm
2009-01-01
Gene delivery by human immunodeficiency virus type 1 (HIV-1)-based lentiviral vectors (LVs) is efficient, but genomic integration of the viral DNA is strongly biased toward transcriptionally active loci resulting in an increased risk of insertional mutagenesis in gene therapy protocols. Nonviral Sleeping Beauty (SB) transposon vectors have a significantly safer insertion profile, but efficient delivery into relevant cell/tissue types is a limitation. In an attempt to combine the favorable features of the two vector systems we established a novel hybrid vector technology based on SB transposase-mediated insertion of lentiviral DNA circles generated during transduction of target cells with integrase (IN)-defective LVs (IDLVs). By construction of a lentivirus-transposon hybrid vector allowing transposition exclusively from circular viral DNA substrates, we demonstrate that SB transposase added in trans directs efficient transposon mobilization from DNA circles in vector-transduced cells. Both transfected plasmid DNA and transduced IDLVs can serve as the source of active transposase. Most important, we demonstrate that the SB transposase overrides the natural lentiviral integration pathway and directs vector integration less frequently toward transcriptional units, resulting in a random genomic integration profile. The novel hybrid vector system combines the attractive features of efficient gene delivery by viral transduction and a safer genomic integration profile by DNA transposition. PMID:19240688
Low-loss silicon nitride waveguide hybridly integrated with colloidal quantum dots.
Xie, Weiqiang; Zhu, Yunpeng; Aubert, Tangi; Verstuyft, Steven; Hens, Zeger; Van Thourhout, Dries
2015-05-01
Silicon nitride waveguides with a monolayer of colloidal quantum dots embedded inside were fabricated using a low-temperature deposition process and an optimized dry etching step for the composite layers. We experimentally demonstrated the luminescence of the embedded quantum dots is preserved and the loss of these hybrid waveguide wires is as low as 2.69dB/cm at 900nm wavelength. This hybrid integration of low loss silicon nitride photonics with active emitters offers opportunities for optical sources operating over a very broad wavelength range. PMID:25969303
Heterogeneously integrated 2.0 ?m CW hybrid silicon lasers at room temperature.
Spott, Alexander; Davenport, Michael; Peters, Jon; Bovington, Jock; Heck, Martijn J R; Stanton, Eric J; Vurgaftman, Igor; Meyer, Jerry; Bowers, John
2015-04-01
Here we experimentally demonstrate room temperature, continuous-wave (CW), 2.0 ?m wavelength lasers heterogeneously integrated on silicon. Molecular wafer bonding of InP to Si is employed. These hybrid silicon lasers operate CW up to 35°C and emit up to 4.2 mW of single-facet CW power at room temperature. III-V tapers transfer light from a hybrid III-V/silicon optical mode into a Si waveguide mode. These lasers enable the realization of a number of sensing and detection applications in compact silicon photonic systems. PMID:25831364
Integrated thermal management of a hybrid electric vehicle
Richard M. Traci; Robert Acebal; Tom Mohler
1999-01-01
A thermal management methodology, based on the Vehicle Integrated Thermal Management Analysis Code (VITMAC), has been developed for a notional vehicle employing the all-electric combat vehicle (AECV) concept. AECV uses a prime power source, such as a diesel, to provide mechanical energy which is converted to electrical energy and stored in a central energy storage system consisting of flywheels, batteries
A Hybrid Object Matching Method for Deep Web Information Integration
Pengpeng Zhao; Chao Lin; Wei Fang; Zhiming Cui
2007-01-01
Object matching is a crucial step to integration of Deep Web sources. Existing methods suppose that record extraction and attribute segmentation are of high accuracy. But because of limitation of extraction techniques, information gained through the above methods is often incomplete. If we match object base on noisy and incomplete information, we can not achieve satisfactory performance. This paper proposes
Outcome of the First wwPDB Hybrid/Integrative Methods Task Force Workshop.
Sali, Andrej; Berman, Helen M; Schwede, Torsten; Trewhella, Jill; Kleywegt, Gerard; Burley, Stephen K; Markley, John; Nakamura, Haruki; Adams, Paul; Bonvin, Alexandre M J J; Chiu, Wah; Peraro, Matteo Dal; Di Maio, Frank; Ferrin, Thomas E; Grünewald, Kay; Gutmanas, Aleksandras; Henderson, Richard; Hummer, Gerhard; Iwasaki, Kenji; Johnson, Graham; Lawson, Catherine L; Meiler, Jens; Marti-Renom, Marc A; Montelione, Gaetano T; Nilges, Michael; Nussinov, Ruth; Patwardhan, Ardan; Rappsilber, Juri; Read, Randy J; Saibil, Helen; Schröder, Gunnar F; Schwieters, Charles D; Seidel, Claus A M; Svergun, Dmitri; Topf, Maya; Ulrich, Eldon L; Velankar, Sameer; Westbrook, John D
2015-07-01
Structures of biomolecular systems are increasingly computed by integrative modeling that relies on varied types of experimental data and theoretical information. We describe here the proceedings and conclusions from the first wwPDB Hybrid/Integrative Methods Task Force Workshop held at the European Bioinformatics Institute in Hinxton, UK, on October 6 and 7, 2014. At the workshop, experts in various experimental fields of structural biology, experts in integrative modeling and visualization, and experts in data archiving addressed a series of questions central to the future of structural biology. How should integrative models be represented? How should the data and integrative models be validated? What data should be archived? How should the data and models be archived? What information should accompany the publication of integrative models? PMID:26095030
Monte Carlo Monte Carlo at Work by Gary D. Doolen and John Hendricks E very second nearly 10,000,000,000 "random" numbers are being generated on computers around the world for Monte Carlo solutions to problems hundreds of full-time careers invested in the fine art of generating Monte Carlo solutions--a livelihood
Barends, Thomas; White, Thomas A; Barty, Anton; Foucar, Lutz; Messerschmidt, Marc; Alonso-Mori, Roberto; Botha, Sabine; Chapman, Henry; Doak, R Bruce; Galli, Lorenzo; Gati, Cornelius; Gutmann, Matthias; Koglin, Jason; Markvardsen, Anders; Nass, Karol; Oberthur, Dominik; Shoeman, Robert L; Schlichting, Ilme; Boutet, Sébastien
2015-05-01
Serial femtosecond crystallography (SFX) is an emerging method for data collection at free-electron lasers (FELs) in which single diffraction snapshots are taken from a large number of crystals. The partial intensities collected in this way are then combined in a scheme called Monte Carlo integration, which provides the full diffraction intensities. However, apart from having to perform this merging, the Monte Carlo integration must also average out all variations in crystal quality, crystal size, X-ray beam properties and other factors, necessitating data collection from thousands of crystals. Because the pulses provided by FELs running in the typical self-amplified spontaneous emission (SASE) mode of operation have very irregular, spiky spectra that vary strongly from pulse to pulse, it has been suggested that this is an important source of variation contributing to inaccuracies in the intensities, and that, by using monochromatic pulses produced through a process called self-seeding, fewer images might be needed for Monte Carlo integration to converge, resulting in more accurate data. This paper reports the results of two experiments performed at the Linac Coherent Light Source in which data collected in both SASE and self-seeded mode were compared. Importantly, no improvement attributable to the use of self-seeding was detected. In addition, other possible sources of variation that affect SFX data quality were investigated, such as crystal-to-crystal variations reflected in the unit-cell parameters; however, these factors were found to have no influence on data quality either. Possibly, there is another source of variation as yet undetected that affects SFX data quality much more than any of the factors investigated here. PMID:25931080
Path-Integral Monte Carlo for the Gauge-Fixed Berry Connection and the Local Z2 Berry Phase
NASA Astrophysics Data System (ADS)
Motoyama, Yuichi; Todo, Synge
We present a general formula of the gauge-fixed Berry connection which can be evaluated by path-integral Monte Carlo method. We also propose that the gauge-fixed local Berry connection can be another effective tool to estimate precisely the quantum critical point. For a demonstration, we calculate the gauge-fixed Berry connection and the local Z2 Berry phase of the antiferromagnetic Heisenberg model on a staggered bond-alternating ladder, and estimated quantum critical point is consistent with other methods.
NASA Astrophysics Data System (ADS)
Prosmiti, R.; Barragán, P.; Pérez de Tudela, R.; Villarreal, P.; Delgado-Barrio, G.
2012-11-01
Classical and path integral Monte Carlo studies for the H+5 cluster and its deuterated counterpart are reported, based on an analytical CCSD(T) potential surface, and a novel realistic DFT "on the fly" based potential schemes. Thermal equilibrium energies and probability density distributions are obtained for H+5 and D+5, and their molecular structure shows strong spatial delocalization with highly anharmonic character. The implementation of such combined PIMC/DFT approach to study nuclear quantum fluctuation on the electronic properties of larger protonated hydrogen clusters is also discussed.
NASA Astrophysics Data System (ADS)
Paolini, Stefano; Ancilotto, Francesco; Toigo, Flavio
2007-03-01
The local order around alkali (Li+ and Na+) and alkaline-earth (Be+, Mg+, and Ca+) ions in He4 clusters has been studied using ground-state path integral Monte Carlo calculations. The authors apply a criterion based on multipole dynamical correlations to discriminate between solidlike and liquidlike behaviors of the He4 shells coating the ions. As it was earlier suggested by experimental measurements in bulk He4, their findings indicate that Be+ produces a solidlike ("snowball") structure, similar to alkali ions and in contrast to the more liquidlike He4 structure embedding heavier alkaline-earth ions.
Utrecht, Universiteit
dei Corvi (Middle^Upper Miocene, northern Italy) F.J. Hilgen a;Ã , H. Abdul Aziz b , W. Krijgsman b della Terra, Univ. `G. D'Annunzio', via dei Vestini 31, 66013 Chieti Scalo, Italy d Dip. di Scienze^Upper Miocene) of the Monte dei Corvi section located in northern Italy. The detailed biostratigraphic analysis
The Markov chain Monte Carlo method: an approach to approximate counting and integration
Mark Jerrum; Alistair Sinclair
1996-01-01
In the area of statistical physics, Monte Carlo algorithms based on Markov chain simulation have been in use for many years. The validity of these algorithms depends cru- cially on the rate of convergence to equilibrium of the Markov chain being simulated. Unfortunately, the classical theory of stochastic processes hardly touches on the sort of non-asymptotic analysis required in this
Bayesian Estimates of Equation System Parameters: An Application of Integration by Monte Carlo
Tuen Kloek; Herman K van Dijk
1978-01-01
Monte Carlo (MC) is used to draw parameter values from a distribution defined on the structural parameter space of an equation system. Making use of the prior density, the likelihood, and Bayes' Theorem it is possible to estimate posterior moments of both structural and reduced form parameters. The MC method allows a rather liberal choice of prior distributions. The number
Zhao, L; Clapsaddle, B; Jr., J S; Schaefer, D; Shea, K
2004-10-15
A sol-gel approach for the synthesis of hybrid nanocomposites of iron oxide and bridged polysilsesquioxanes has been established. The procedures allow for the simultaneous formation of iron oxide and polysilsesquioxane networks in monolithic xerogels and aerogels. These hybrid nanocomposites are synthesized from FeCl{sub 3} {center_dot} 6H{sub 2}O and functionalized silsesquioxane monomers in a one-pot reaction using epoxides as a gelation agent. The porosity and microstructure of the materials has been determined by nitrogen porosimetry, electron microscopy and ultra small angle X-ray scattering (USAXS). The hybrid nanocomposites exhibit a uniform dispersion of both components with no evidence for phase separation at length scales > 5 nm. At this limit of resolution it is not possible to distinguish between two independent interpenetrating networks integrated at molecular length scales or a random copolymer or mixtures of both.
Integrated thermal management of a hybrid electric vehicle
Traci, R.M.; Acebal, R. [Science Applications International Corp., La Jolla, CA (United States)] [Science Applications International Corp., La Jolla, CA (United States); Mohler, T. [United Defense L.P., Santa Clara, CA (United States)] [United Defense L.P., Santa Clara, CA (United States)
1999-01-01
A thermal management methodology, based on the Vehicle Integrated Thermal Management Analysis Code (VITMAC), has been developed for a notional vehicle employing the All-Electric Combat Vehicle (AECV) concept. AECV uses a prime power source, such as a diesel, to provide mechanical energy which is converted to electrical energy and stored in a central energy storage system consisting of flywheels, batteries and/or capacitors. The combination of prime power and stored energy powers the vehicle drive system and also advanced weapons subsystems such as an ETC or EM gun, electrically driven lasers, an EM armor system and an active suspension. Every major system is electrically driven with energy reclamation when possible from braking and gun recoil. Thermal management of such a complicated energy transfer and utilization system is a major design consideration due to the substantial heat rejection requirements. In the present paper, an overall integrated thermal management system (TMS) is described which accounts for energy losses from each subsystem component, accepts the heat using multiple coolant loops and expels the heat from the vehicle. VITMAC simulations are used to design the TMS and to demonstrate that a conventional TMS approach is capable of successfully handling vehicle heat rejection requirements under stressing operational conditions.
NASA Astrophysics Data System (ADS)
Militzer, B.; Khairallah, S. A.
2008-12-01
In this talk, four different computational methods will be compared, their advantages and disadvantages discussed, and their application to solid and fluid helium described. Helium was chosen because it is a major component of giant gas planets, was studied recently with shock wave experiments [1], and is comparatively simple to treat computationally that allowed us to apply all these different techniques. First we studied the insulator-to-metal transition in solid helium at high pressure. Density functional theory (DFT) was used to optimize the c/a ratio in the h.c.p. solid. Applying groundstate quantum Monte Carlo (QMC) [3], one finds that DFT predicts band gaps that are 4 eV too small. This inaccuracy means that DFT underestimates the metallization density by 20% and the metallization pressure by 40%. The band gaps computed with QMC are in very good agreement with GW calculations. However, GW cannot be used to correct the total energies and the equation of state (EOS). QMC yields the energy directly, and the correlation energy that is missing in DFT can be determined. To study fluids, DFT can also be combined with molecular dynamics for the nuclei by treating the electrons either in the instantaneous groundstate or by including thermal electronic excitations. At temperature above 20000K, electronic excitations affect the EOS significantly and make the material more compressible in shock wave experiments [1,2]. Despite the band gap problem in DFT, one would expect this method describe electronic excitations qualitatively. But it has not yet been demonstrated whether it is quantitatively accurate to determine correction to the EOS due to thermally excited electrons. By comparing with path integral Monte Carlo (PIMC) [4], we demonstrate DFT-MD EOS is surprising accurate but the method eventually becomes impractical because too many electronic orbital must be considered. PIMC, on the other hand, becomes more efficient at high temperature. In [4], we show that PIMC and DFT-MD can be combined to obtain one coherent EOS over several orders of magnitude in temperature. Finally, we compare our computed EOS with recent shock wave experiments [1]. We find good agreement between first-principles simulations and those experiments where the sample has been precompressed statically before the shock is launched. For the experiments without precompression, one finds that our first- principles EOS predicts a lower compressibility than was measured. This work was supported by NSF and NASA. A part of the computational resources were provided by NERSC. [1] J. Eggert et al., Phys. Rev. Lett. 100 (2008) 124503 [2] B. Militzer, Phys. Rev. Lett. 97 (2006) 175501. [3] S. Khairrallah and B. Militzer, Phys. Rev. Lett. 101 (2008) 106407. [4] B. Militzer, cond-mat/08050317.
Path-integral Monte Carlo method for the local Z2 Berry phase
NASA Astrophysics Data System (ADS)
Motoyama, Yuichi; Todo, Synge
2013-02-01
We present a loop cluster algorithm Monte Carlo method for calculating the local Z2 Berry phase of the quantum spin models. The Berry connection, which is given as the inner product of two ground states with different local twist angles, is expressed as a Monte Carlo average on the worldlines with fixed spin configurations at the imaginary-time boundaries. The “complex weight problem” caused by the local twist is solved by adopting the meron cluster algorithm. We present the results of simulation on the antiferromagnetic Heisenberg model on an out-of-phase bond-alternating ladder to demonstrate that our method successfully detects the change in the valence bond pattern at the quantum phase transition point. We also propose that the gauge-fixed local Berry connection can be an effective tool to estimate precisely the quantum critical point.
NASA Astrophysics Data System (ADS)
Reese, Terrence; Miller, Bruce
2008-10-01
A quantum particle (qp) in a fluid near the liquid vapor-critical point creates a volume of altered density in which it becomes localized. In previous research we have used the Path Integral Monte Carlo (PIMC) technique to investigate the properties of the qp-fluid molecule system. The path integral formulation represents the quantum particle as a closed chain of P classical particles in which the quantum spread of the qp is manifest in the spread of the chain. This formulation allows classical Monte Carlo techniques to be used to compute quantum mechanical equilibrium values. In this work we will explore the convergence of the PIMC technique for a qp equilibrated in a Lennard-Jones fluid whose characteristics resemble Xenon. The computations were done for two densities of the fluid at 300 and 340K. The correlation function, the number of independent samples and the radius of gyration were computed. The autocorrelation function for the pick-off decay rate was computed for increments of 500 and 5000. It was discovered that for the lower density the computed values of the pick-off decay rate became independent within an increment of 500, while near the critical density an increment of more than 1000 was required for the values to become uncorrelated.
Rapid microarray processing using a disposable hybridization chamber with an integrated micropump.
Rupp, Jochen; Schmidt, Manuela; Münch, Susanne; Cavalar, Markus; Steller, Ulf; Steigert, Jürgen; Stumber, Michael; Dorrer, Christian; Rothacher, Peter; Zengerle, Roland; Daub, Martina
2012-04-01
We present a disposable microarray hybridization chamber with an integrated micropump to speed up diffusion based reaction kinetics by generating convective flow. The time-to-result for the hybridization reaction was reduced from 60 min (standard protocol) down to 15 min for a commercially available microarray. The integrated displacement micropump is pneumatically actuated. It includes two active microvalves and is designed for low-cost, high volume manufacturing. The setup is made out of two microstructured polymer parts realized in polycarbonate (PC) separated by a 25 ?m thermoplastic elastomer (TPE) membrane. Pump rate can be controlled between 0.3 ?l s(-1) and 5.7 ?l s(-1) at actuation frequencies between 0.2 Hz and 8.0 Hz, respectively. PMID:22361890
Hybrid photonic integrated circuits for faster and greener optical communication networks
NASA Astrophysics Data System (ADS)
Stampoulidis, L.; Kehayas, E.; Zimmermann, L.
2011-01-01
We present current development efforts on hybrid photonic integration for new generation "faster and greener" Tb/scapacity optical networks. On the physical layer, we present the development of a versatile, silicon-based photonic integration platform that acts as a technology "blender" bringing together different material systems including III-V and silicon-based semiconductors. The platform is also used to implement the so-called O-to-O (optical-to-optical) functionalities by patterning low-loss passive components such as MMI couplers and delay interferometers. With these passive building blocks as well as the ability for hybrid assembly of active material, we demonstrate the fabrication of key optical transport and routing devices such as optical demodulators and all-optical wavelength converters. These devices can now be used to fabricate chip-scale 100 GbE transceiver PICs and Tb/s-capacity wavelength switching platforms.
Nigar Kantarci-Carsibasi; Turkan Haliloglu; Pemra Doruker
2008-01-01
Conformational transitions between open\\/closed or free\\/bound states in proteins possess functional importance. We propose a technique in which the collective modes obtained from an anisotropic network model (ANM) are used in conjunction with a Monte Carlo (MC) simulation approach, to investigate conformational transition pathways and pathway intermediates. The ANM-MC technique is applied to adenylate kinase (AK) and hemoglobin. The iterative
Automatic on-chip RNA–DNA hybridization assay with integrated phase change microvalves
Xuan Weng; Hai Jiang; Junsheng Wang; Shu Chen; Honghe Cao; Dongqing Li
2012-01-01
An RNA–DNA hybridization assay microfluidic chip integrated with electrothermally actuated phase change microvalves for detecting pathogenic bacteria is presented in this paper. In order to realize the sequential loading and washing processes required in such an assay, gravity-based pressure-driven flow and phase-change microvalves were used in the microfluidic chip. Paraffin wax was used as the phase change material in the
Amir Boag; Uri Shemer; Raphael Kastner
2004-01-01
Novel hybrid (local- global) absorbing boundary condi- tions (ABCs) are proposed for the truncation of computational domains in finite-method analysis of open-region problems. The pertinent bound- ary integration is accelerated by the nonuniform grid-interpolation scheme, resulting in a fast algorithm for treating electrically large ob- jects with largely concave outer boundaries. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett
40Gb\\/s All-Optical Processing Systems Using Hybrid Photonic Integration Technology
Efstratios Kehayas; Dimitris Tsiokos; Paraskevas Bakopoulos; Dimitris Apostolopoulos; Dimitrios Petrantonakis; Leontios Stampoulidis; Alistair Poustie; Rob McDougall; Graeme Maxwell; Yong Liu; Shaoxian Zhang; H. J. S. Dorren; Jorge Seoane; P Van Holm-Nielsen; Palle Jeppesen; Hercules Avramopoulos
2006-01-01
This paper presents an experimental performance characterization of all-optical subsystems at 40 Gb\\/s using interconnected hybrid integrated all-optical semiconductor optical amplifier (SOA) Mach-Zehnder interferometer (MZI) gates and flip-flop prototypes. It was shown that optical gates can be treated as generic switching elements and, when efficiently interconnected, can form larger and more functional network subsystems. Specifically, this paper reports on all-optical
Samuel Charlot; Anne-Marie Gué; Josiane Tasselli; Antoine Marty; Patrick Abgrall; Daniel Estève
2008-01-01
This paper describes a new technology permitting a hybrid integration of silicon chips in polymer (PDMS and SU8) microfluidic structures. This two-step technology starts with transferring the silicon device onto a rigid substrate (typically PCB) and planarizing it, and then it proceeds with stacking of the polymer-made fluidic network onto the device. The technology is low cost, based on screen
Integration of Hybrid Fibre Radio and IEEE 802.11 WLAN network Kenneth K L. Ho and J. E. Mitchell
Haddadi, Hamed
Integration of Hybrid Fibre Radio and IEEE 802.11 WLAN network Kenneth K L. Ho and J. E. Mitchell radio (HFR), a method in integrating wireless and optical networks, large part of the radio complexity in deploying IEEE 802.11 wireless local access network (WLAN) through integration with HFR. We will discuss its
NASA Astrophysics Data System (ADS)
Yang, Diwu; Xing, Da; Tan, Yi; Gu, Huaimin; Yang, Sihua
2006-04-01
A prototype B-scan photoacoustic tomography system is developed. It integrates pumping fiber, ultrasound coupling medium, and a transducer array into a novel hybridized scanning head. By moving the scanning head a photoacoustic tomography can be obtained in the reflection mode. Concentration-adjustable glycerite is used as the ultrasonic coupling medium to match the ultrasonic velocities in tissues, reducing the acoustic reflection, eliminating the acoustic refraction, and rectifying the acoustic path difference. This system is used to image graphite phantom in tissue and human blood vessels. Our experimental results show that this integrative system has the potential for fast photoacoustic imaging.
NASA Astrophysics Data System (ADS)
Schumacher, Andreas B.; Krabe, Detlef; Dieckroeger, Jens; Spott, Thorsten; Kraeker, Tobias; Martins, Evely; Zavrsnik, Miha; Schneider, Hartmut W.; Baumann, Ingo
2003-03-01
We built a 20 channel, 200 GHz, fully reconfigurable optical add-/drop multiplexer with integrated variable optical attenuators and power monitor diodes. A single planar lightwave circuit chip contains demultiplexer, switch array, attenuators and multiplexers. It also serves as an "optical motherboard" for a hybrid, flip-chip assembly containing four 10-channel photo detector arrays. A thermal management concept which considers both microscopic and macroscopic aspects of the device was developed. The final device exhibits an insertion loss of 9 dB from "in"- to "through"-port, a 1 dB bandwidth of >50 GHz and switch extinction ratios in excess of 40 dB.
Urbic, T.; Holovko, M. F.
2011-01-01
Associative version of Henderson-Abraham-Barker theory is applied for the study of Mercedes–Benz model of water near hydrophobic surface. We calculated density profiles and adsorption coefficients using Percus-Yevick and soft mean spherical associative approximations. The results are compared with Monte Carlo simulation data. It is shown that at higher temperatures both approximations satisfactory reproduce the simulation data. For lower temperatures, soft mean spherical approximation gives good agreement at low and at high densities while in at mid range densities, the prediction is only qualitative. The formation of a depletion layer between water and hydrophobic surface was also demonstrated and studied. PMID:21992334
Path-integral-expanded-ensemble Monte Carlo method in treatment of the sign problem for fermions
NASA Astrophysics Data System (ADS)
Voznesenskiy, M. A.; Vorontsov-Velyaminov, P. N.; Lyubartsev, A. P.
2009-12-01
Expanded-ensemble Monte Carlo method with Wang-Landau algorithm was used for calculations of the ratio of partition functions for classes of permutations in the problem of several interacting quantum particles (fermions) in an external field. Simulations for systems consisting of 2 up to 7 interacting particles in harmonic or Coulombic field were performed. The presented approach allows one to carry out calculations for low enough temperatures that makes it possible to extract data for the ground-state energy and low-temperature thermodynamics.
Xiong, Pan; Liu, Borui; Teran, Vincent; Zhao, Yu; Peng, Lele; Wang, Xin; Yu, Guihua
2014-08-26
Hybrid inorganic/graphene two-dimensional (2D) nanostructures can offer vastly open large surface areas for ion transport and storage and enhanced electron transport, representing a promising material platform for next-generation energy storage. Here we report chemically integrated hybrid ZnMn2O4/graphene nanosheets synthesized via a facile two-step method for greatly enhanced lithium storage capability. The hybrid 2D nanosheets are composed of ultrafine ZnMn2O4 nanocrystals with a mean diameter of ?4 nm attached to and well dispersed on the surface of reduced graphene oxide sheets. The hybrid nanosheets based anode offers a high capacity of ?800 mAh g(–1) at a current rate of 500 mA g(–1), excellent rate capability, and long-term cyclability with reversible capacity of ?650 mAh g(–1) over 1500 cycles at a current density of 2000 mA g(–1). Moreover, when tested in a temperature range of ?0–60 °C, the designed anode can maintain high discharge capacities from 570 to 820 mAh g(–1). PMID:25072966
Los Alamos hybrid environment: an integrated development/configuration management system
Cort, G.
1984-01-01
I present the details of a hybrid configuration management system that utilizes a commercial configuration management tool (Softool's Change and Configuration Control environment) to monitor and control the development of mission-critical software systems at the Los Alamos Weapons Neutron Research Facility. The hybrid system combines features of the VMS host operating system and elements of the tool environment to integrate a flexible development environment with a very powerful automated configuration management system. The features of this system are presented with particular emphasis on the benefits of the hybrid approach. The complementary nature of the constituent environments is described. Special attention is given the issues of operational tradeoffs, personnel interaction and utilization, management visibility and overall system performance. It is shown that by employing a special interface data structure, the hybrid environment supports a much higher level of automation (of both development and configuration management activities) than is realizable in either environment individually. Examples are provided to illustrate the extent to which development activities and all phases of configuration management can be automated under this system. It is shown that in the process of providing a rigorous configuration management environment, the system remains virtually transparent to software development personnel and actually enhances the programmer's capabilities.
NASA Astrophysics Data System (ADS)
Krzakala, Florent; Rosso, Alberto; Semerjian, Guilhem; Zamponi, Francesco
2008-10-01
The cavity method is a well-established technique for solving classical spin models on sparse random graphs (mean-field models with finite connectivity). Laumann [Phys. Rev. B 78, 134424 (2008)] proposed recently an extension of this method to quantum spin-1/2 models in a transverse field, using a discretized Suzuki-Trotter imaginary-time formalism. Here we show how to take analytically the continuous imaginary-time limit. Our main technical contribution is an explicit procedure to generate the spin trajectories in a path-integral representation of the imaginary-time dynamics. As a side result we also show how this procedure can be used in simple heat bath Monte Carlo simulations of generic quantum spin models. The replica symmetric continuous-time quantum cavity method is formulated for a wide class of models and applied as a simple example on the Bethe lattice ferromagnet in a transverse field. The results of the methods are confronted with various approximation schemes in this particular case. On this system we performed quantum Monte Carlo simulations that confirm the exactness of the cavity method in the thermodynamic limit.
Mohamed S. Zaky; Ehab M. Ismaeil; Mahmoud M. Khater
2012-01-01
This article presents a gain-scheduling adaptive proportional-integral speed controller for field-oriented control of hybrid stepper motor drives. The proportional-integral gains are designed to be a function of the speed error and are allowed to vary within a pre-determined range. This, therefore, eliminates the problems suffered by the conventional proportional-integral controller. The performance of the proposed gain-scheduled proportional-integral controller with field-oriented
NASA Astrophysics Data System (ADS)
Filinov, V. S.; Bonitz, M.; Ivanov, Y. B.; Ilgenfritz, E.-M.; Fortov, V. E.
2015-02-01
Based on the constituent quasiparticle model of the quark-gluon plasma (QGP), color quantum path-integral Monte-Carlo (PIMC) calculations of the thermodynamic properties of the QGP are performed. We extend our previous zero chemical potential simulations to the QGP at finite baryon chemical potential. The results indicate that color PIMC can be applied not only above the QCD critical temperature $T_c$ but also below $T_c$. Besides reproducing the lattice equation of state our approach yields also valuable additional insight into the internal structure of the QGP, via the pair distribution functions of the various quasiparticles. In particular, the pair distribution function of gluons reflects the existence of gluon-gluon bound states at low temperatures and $\\mu=175$ MeV, i.e. glueballs, while meson-like bound states are not found.
Chen, Chia-Lin; Wang, Yuchuan; Lee, Jason J. S.; Tsui, Benjamin M. W.
2008-01-01
The authors developed and validated an efficient Monte Carlo simulation (MCS) workflow to facilitate small animal pinhole SPECT imaging research. This workflow seamlessly integrates two existing MCS tools: simulation system for emission tomography (SimSET) and GEANT4 application for emission tomography (GATE). Specifically, we retained the strength of GATE in describing complex collimator?detector configurations to meet the anticipated needs for studying advanced pinhole collimation (e.g., multipinhole) geometry, while inserting the fast SimSET photon history generator (PHG) to circumvent the relatively slow GEANT4 MCS code used by GATE in simulating photon interactions inside voxelized phantoms. For validation, data generated from this new SimSET-GATE workflow were compared with those from GATE-only simulations as well as experimental measurements obtained using a commercial small animal pinhole SPECT system. Our results showed excellent agreement (e.g., in system point response functions and energy spectra) between SimSET-GATE and GATE-only simulations, and, more importantly, a significant computational speedup (up to ?10-fold) provided by the new workflow. Satisfactory agreement between MCS results and experimental data were also observed. In conclusion, the authors have successfully integrated SimSET photon history generator in GATE for fast and realistic pinhole SPECT simulations, which can facilitate research in, for example, the development and application of quantitative pinhole and multipinhole SPECT for small animal imaging. This integrated simulation tool can also be adapted for studying other preclinical and clinical SPECT techniques. PMID:18697552
NASA Astrophysics Data System (ADS)
Belof, Jonathan; Dubois, Jonathan
2013-06-01
Warm dense matter (WDM), the regime of degenerate and strongly coupled Coulomb systems, is of great interest due to it's importance in understanding astrophysical processes and high energy density laboratory experiments. Path Integral Monte Carlo (PIMC) presents a particularly attractive formalism for tackling outstanding questions in WDM, in that electron correlation can be calculated exactly, with the nuclear and electronic degrees of freedom on equal footing. Here we present an efficient means of solving the Feynman path integral numerically by variational optimization of a trial density matrix, a method originally proposed for simple potentials by Feynman and Kleinert, and we show that this formalism provides an accurate description of warm dense matter with a number of unique advantages over other PIMC approaches. An exchange interaction term is derived for the variationally optimized path, as well as a numerically efficient scheme for dealing with long-range electrostatics. Finally, we present results for the pair correlation functions and thermodynamic observables of the spin polarized electron gas, warm dense hydrogen and all-electron warm dense carbon within the presented VPT-PIMC formalism. Warm dense matter (WDM), the regime of degenerate and strongly coupled Coulomb systems, is of great interest due to it's importance in understanding astrophysical processes and high energy density laboratory experiments. Path Integral Monte Carlo (PIMC) presents a particularly attractive formalism for tackling outstanding questions in WDM, in that electron correlation can be calculated exactly, with the nuclear and electronic degrees of freedom on equal footing. Here we present an efficient means of solving the Feynman path integral numerically by variational optimization of a trial density matrix, a method originally proposed for simple potentials by Feynman and Kleinert, and we show that this formalism provides an accurate description of warm dense matter with a number of unique advantages over other PIMC approaches. An exchange interaction term is derived for the variationally optimized path, as well as a numerically efficient scheme for dealing with long-range electrostatics. Finally, we present results for the pair correlation functions and thermodynamic observables of the spin polarized electron gas, warm dense hydrogen and all-electron warm dense carbon within the presented VPT-PIMC formalism. Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344.
Bichutskiy, Vadim Y.; Colman, Richard; Brachmann, Rainer K.; Lathrop, Richard H.
2006-01-01
Complex problems in life science research give rise to multidisciplinary collaboration, and hence, to the need for heterogeneous database integration. The tumor suppressor p53 is mutated in close to 50% of human cancers, and a small drug-like molecule with the ability to restore native function to cancerous p53 mutants is a long-held medical goal of cancer treatment. The Cancer Research DataBase (CRDB) was designed in support of a project to find such small molecules. As a cancer informatics project, the CRDB involved small molecule data, computational docking results, functional assays, and protein structure data. As an example of the hybrid strategy for data integration, it combined the mediation and data warehousing approaches. This paper uses the CRDB to illustrate the hybrid strategy as a viable approach to heterogeneous data integration in biomedicine, and provides a design method for those considering similar systems. More efficient data sharing implies increased productivity, and, hopefully, improved chances of success in cancer research. (Code and database schemas are freely downloadable, http://www.igb.uci.edu/research/research.html.) PMID:19458771
NASA Astrophysics Data System (ADS)
Uyemura, John P.; Austin, Blanca L.
1992-04-01
Photodiodes are integrated into complementary metal-oxide semiconductor very-large-scale integration logic circuits to provide a hybrid interface between parallel-optical and electronic computing formats. This permits direct parallel transfer from an optical processor or storage element to a standard electronic system. The optical input beams may be viewed as control signals or as logical inputs that increase the system complexity and permit direct interaction of the electronic logic circuits with the optical beam states. Applications of the approach include hybrid optical-electronic logic gates, optical control of electronic data paths, and optically reconfigured very-large-scale integration circuits.
Reisinger, Jürgen; Rumpler, Silvia; Lion, Thomas; Ambros, Peter F
2006-04-01
For many Epstein-Barr virus (EBV)-associated malignancies, it is still a matter of controversy whether infected cells harbor episomal or chromosomally integrated EBV genomes or both. It is well established that the expression of EBV genes per se carries oncogenic potential, but the discrimination between episomal and integrated forms is of great relevance because integration events can contribute to the oncogenic properties of EBV, whereas host cells that exclusively harbor viral episomes may not carry the risks mediated by chromosomal integration. This notion prompted us to establish a reliable technique that not only allows to unequivocally discriminate episomal from integrated EBV DNA, but also provides detailed insights into the genomic organization of the virus. Here, we show that dynamic molecular combing of host cell DNA combined with fluorescence in situ hybridization (FISH) using EBV-specific DNA probes facilitate unambiguous discrimination of episomal from integrated viral DNA. Furthermore, the detection of highly elongated internal repeat 1 (IR1) sequences provides evidence that this method permits detection of major genomic alterations within the EBV genome. Thus, fiber FISH may also provide valuable insights into the genomic organization of viral genomes other than EBV. PMID:16217752
Integration of multisensor hybrid reasoners to support personal autonomy in the smart home.
Valero, Miguel Ángel; Bravo, José; Chamizo, Juan Manuel García; López-de-Ipiña, Diego
2014-01-01
The deployment of the Ambient Intelligence (AmI) paradigm requires designing and integrating user-centered smart environments to assist people in their daily life activities. This research paper details an integration and validation of multiple heterogeneous sensors with hybrid reasoners that support decision making in order to monitor personal and environmental data at a smart home in a private way. The results innovate on knowledge-based platforms, distributed sensors, connected objects, accessibility and authentication methods to promote independent living for elderly people. TALISMAN+, the AmI framework deployed, integrates four subsystems in the smart home: (i) a mobile biomedical telemonitoring platform to provide elderly patients with continuous disease management; (ii) an integration middleware that allows context capture from heterogeneous sensors to program environment's reaction; (iii) a vision system for intelligent monitoring of daily activities in the home; and (iv) an ontologies-based integrated reasoning platform to trigger local actions and manage private information in the smart home. The framework was integrated in two real running environments, the UPM Accessible Digital Home and MetalTIC house, and successfully validated by five experts in home care, elderly people and personal autonomy. PMID:25232910
G. Jacucci; E. Omerti
1983-01-01
The two body contribution to the radial distribution function of quantum hard spheres is calculated using the Monte Carlo method based on path integrals. Hard core boundary conditions are taken into account by means of an ‘‘image’’ approximation obtaining accurate numerical results.
All-fiber hybrid photon-plasmon circuits: integrating nanowire plasmonics with fiber optics.
Li, Xiyuan; Li, Wei; Guo, Xin; Lou, Jingyi; Tong, Limin
2013-07-01
We demonstrate all-fiber hybrid photon-plasmon circuits by integrating Ag nanowires with optical fibers. Relying on near-field coupling, we realize a photon-to-plasmon conversion efficiency up to 92% in a fiber-based nanowire plasmonic probe. Around optical communication band, we assemble an all-fiber resonator and a Mach-Zehnder interferometer (MZI) with Q-factor of 6 × 10(6) and extinction ratio up to 30 dB, respectively. Using the MZI, we demonstrate fiber-compatible plasmonic sensing with high sensitivity and low optical power. PMID:23842356
Progress of Integral Experiments in Benchmark Fission Assemblies for a Blanket of Hybrid Reactor
NASA Astrophysics Data System (ADS)
Liu, R.; Zhu, T. H.; Yan, X. S.; Lu, X. X.; Jiang, L.; Wang, M.; Han, Z. J.; Wen, Z. W.; Lin, J. F.; Yang, Y. W.
2014-04-01
This article describes recent progress in integral neutronics experiments in benchmark fission assemblies for the blanket design in a hybrid reactor. The spherical assemblies consist of three layers of depleted uranium shells and several layers of polyethylene shells, separately. In the assemblies with centralizing the D-T neutron source, the plutonium production rates, uranium fission rates and leakage neutron spectra are measured. The measured results are compared to the calculated ones with the MCNP-4B code and ENDF/B-VI library data, available.
Integrated hybrid Si/InGaAs 50 Gb/s DQPSK receiver.
Faralli, Stefano; Nguyen, Kimchau N; Peters, Jonathan D; Spencer, Daryl T; Blumenthal, Daniel J; Bowers, John E
2012-08-27
A monolithic 25 Gbaud DQPSK receiver based on delay interferometers and balanced detection has been designed and fabricated on the hybrid Si/InGaAs platform. The integrated 30 µm long InGaAs p-i-n photodetectors have a responsivity of 0.64 A/W at 1550 nm and a 3dB bandwidth higher than 25 GHz. The delay interferometer shows a delay time of 39.2 ps and an extinction ratio higher than 20 dB. The demodulation of a 25 Gb/s DPSK signal by a single branch of the receiver demonstrates its correct working principle. PMID:23037025
NASA Astrophysics Data System (ADS)
Leow, Shin Woei; Corrado, Carley; Osborn, Melissa; Carter, Sue A.
2013-09-01
Luminescent solar concentrators (LSCs) have the ability to receive light from a wide range of angles, concentrating the captured light onto small photo active areas. This enables greater incorporation of LSCs into building designs as windows, skylights and wall claddings in addition to rooftop installations of current solar panels. Using relatively cheap luminescent dyes and acrylic waveguides to effect light concentration onto lesser photovoltaic (PV) cells, there is potential for this technology to approach grid price parity. We employ a panel design in which the front facing PV cells collect both direct and concentrated light ensuring a gain factor greater than one. This also allows for flexibility in determining the placement and percentage coverage of PV cells during the design process to balance reabsorption losses against the power output and level of light concentration desired. To aid in design optimization, a Monte-Carlo ray tracing program was developed to study the transport of photons and loss mechanisms in LSC panels. The program imports measured absorption/emission spectra and transmission coefficients as simulation parameters with interactions of photons in the panel determined by comparing calculated probabilities with random number generators. LSC panels with multiple dyes or layers can also be simulated. Analysis of the results reveals optimal panel dimensions and PV cell layouts for maximum power output for a given dye concentration, absorbtion/emission spectrum and quantum efficiency.
NASA Astrophysics Data System (ADS)
Filinov, V. S.; Ivanov, Yu. B.; Fortov, V. E.; Bonitz, M.; Levashov, P. R.
2013-03-01
Based on the quasiparticle model of the quark-gluon plasma (QGP), a color quantum path-integral Monte-Carlo (PIMC) method for the calculation of thermodynamic properties and—closely related to the latter—a Wigner dynamics method for calculation of transport properties of the QGP are formulated. The QGP partition function is presented in the form of a color path integral with a new relativistic measure instead of the Gaussian one traditionally used in the Feynman-Wiener path integral. A procedure of sampling color variables according to the SU(3) group Haar measure is developed for integration over the color variable. It is shown that the PIMC method is able to reproduce the lattice QCD equation of state at zero baryon chemical potential at realistic model parameters (i.e., quasiparticle masses and coupling constant) and also yields valuable insight into the internal structure of the QGP. Our results indicate that the QGP reveals quantum liquidlike(rather than gaslike) properties up to the highest considered temperature of 525 MeV. The pair distribution functions clearly reflect the existence of gluon-gluon bound states, i.e., glueballs, at temperatures just above the phase transition, while mesonlike qq¯ bound states are not found. The calculated self-diffusion coefficient agrees well with some estimates of the heavy-quark diffusion constant available from recent lattice data and also with an analysis of heavy-quark quenching in experiments on ultrarelativistic heavy-ion collisions, however, appreciably exceeds other estimates. The lattice and heavy-quark-quenching results on the heavy-quark diffusion are still rather diverse. The obtained results for the shear viscosity are in the range of those deduced from an analysis of the experimental elliptic flow in ultrarelativistic heavy-ions collisions, i.e., in terms the viscosity-to-entropy ratio, 1/4???/S<2.5/4?, in the temperature range from 170 to 440 MeV.
Wendland, D; Ballenegger, V; Alastuey, A
2014-11-14
We compute two- and three-body cluster functions that describe contributions of composite entities, like hydrogen atoms, ions H(-), H2(+), and helium atoms, and also charge-charge and atom-charge interactions, to the equation of state of a hydrogen-helium mixture at low density. A cluster function has the structure of a truncated virial coefficient and behaves, at low temperatures, like a usual partition function for the composite entity. Our path integral Monte Carlo calculations use importance sampling to sample efficiently the cluster partition functions even at low temperatures where bound state contributions dominate. We also employ a new and efficient adaptive discretization scheme that allows one not only to eliminate Coulomb divergencies in discretized path integrals, but also to direct the computational effort where particles are close and thus strongly interacting. The numerical results for the two-body function agree with the analytically known quantum second virial coefficient. The three-body cluster functions are compared at low temperatures with familiar partition functions for composite entities. PMID:25399134
NASA Astrophysics Data System (ADS)
Wendland, D.; Ballenegger, V.; Alastuey, A.
2014-11-01
We compute two- and three-body cluster functions that describe contributions of composite entities, like hydrogen atoms, ions H-, H_2^+, and helium atoms, and also charge-charge and atom-charge interactions, to the equation of state of a hydrogen-helium mixture at low density. A cluster function has the structure of a truncated virial coefficient and behaves, at low temperatures, like a usual partition function for the composite entity. Our path integral Monte Carlo calculations use importance sampling to sample efficiently the cluster partition functions even at low temperatures where bound state contributions dominate. We also employ a new and efficient adaptive discretization scheme that allows one not only to eliminate Coulomb divergencies in discretized path integrals, but also to direct the computational effort where particles are close and thus strongly interacting. The numerical results for the two-body function agree with the analytically known quantum second virial coefficient. The three-body cluster functions are compared at low temperatures with familiar partition functions for composite entities.
Shang, Yu; Li, Ting; Chen, Lei; Lin, Yu; Toborek, Michal; Yu, Guoqiang
2014-01-01
Conventional semi-infinite solution for extracting blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements may cause errors in estimation of BFI (?DB) in tissues with small volume and large curvature. We proposed an algorithm integrating Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in tissue for the extraction of ?DB. The volume and geometry of the measured tissue were incorporated in the Monte Carlo simulation, which overcome the semi-infinite restrictions. The algorithm was tested using computer simulations on four tissue models with varied volumes/geometries and applied on an in vivo stroke model of mouse. Computer simulations shows that the high-order (N???5) linear algorithm was more accurate in extracting ?DB (errors?
Shang, Yu; Lin, Yu; Yu, Guoqiang, E-mail: guoqiang.yu@uky.edu [Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States); Li, Ting [Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States); State Key Laboratory for Electronic Thin Film and Integrated Device, University of Electronic Science and Technology of China, Chengdu 610054 (China); Chen, Lei; Toborek, Michal [Department of Neurosurgery, University of Kentucky, Lexington, Kentucky 40536 (United States)
2014-05-12
Conventional semi-infinite solution for extracting blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements may cause errors in estimation of BFI (?D{sub B}) in tissues with small volume and large curvature. We proposed an algorithm integrating Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in tissue for the extraction of ?D{sub B}. The volume and geometry of the measured tissue were incorporated in the Monte Carlo simulation, which overcome the semi-infinite restrictions. The algorithm was tested using computer simulations on four tissue models with varied volumes/geometries and applied on an in vivo stroke model of mouse. Computer simulations shows that the high-order (N???5) linear algorithm was more accurate in extracting ?D{sub B} (errors?
Hybrid and heterogeneous photonic integrated circuits for high-performance applications
NASA Astrophysics Data System (ADS)
Heck, Martijn J. R.
2015-02-01
Photonic integration based on silicon, silica, or indium phosphide technologies has reached a level of maturity where it has now become an integral part of telecom and datacom networks. However, although impressive levels of integration and bandwidth have been achieved, the performance of these technologies is relatively low, compared to fiber-optics and discrete bulk optics counterparts. This limits their application in more demanding fields like microwave photonics, e.g., for 4G/5G wireless communications, more advanced complex modulation formats for telecommunications, and highly energy-efficient interconnects. The invention of the ultra-low loss waveguide (ULLW) platform, by me and my co-workers at UC Santa Barbara, heralds a new range of applications for photonic integrated circuits. Fiber-like loss performance, with waveguide propagation losses < 0.1 dB/m, has been realized in waveguides with silicon nitride cores. This performance level represents an order of magnitude lower loss than silica-based waveguides, and 2 - 3 orders of magnitude lower than the silicon-on-insulator and indium phosphide PIC platforms. A combination of the silicon, ULLW, and/or indium phosphide platforms can be made using hybrid or heterogeneous integration techniques. Using "the best of both worlds" approach, improved performance can be achieved. I will discuss the opportunities that these technologies offer for various high-performance applications, such as low-noise lasers and oscillators, high-resolution radars and gyroscopes, and high-bandwidth photonic analog-to-digital converters.
NASA Astrophysics Data System (ADS)
Hosseini, Seyed Mahmoud; Shahabian, Farzad
2009-09-01
In this article, the dynamic responses of functionally graded thick hollow cylinders are studied from stochastic view using Monte Carlo method. The FG cylinder is subjected to mechanical shock loads applied to inner surface of cylinder. The FG cylinder is assumed to be in plane strain conditions and axisymmetry conditions. To obtain the radial displacement in each point, the Navier equation in displacement form is derived using isotropic elements. To solve the problem, the combined numerical method is used (Galerkin finite element and Newmark finite difference methods). The maximum, mean and minimum values of radial displacement also variance of variation in radial displacement are calculated in various points across thickness for different values of volume fraction exponent (in mechanical properties function of FG cylinder).
Integration Issues of Cells into Battery Packs for Plug-in and Hybrid Electric Vehicles: Preprint
Pesaran, A. A.; Kim, G. H.; Keyser, M.
2009-05-01
The main barriers to increased market share of hybrid electric vehicles (HEVs) and commercialization of plug-in HEVs are the cost, safety, and life of lithium ion batteries. Significant effort is being directed to address these issues for lithium ion cells. However, even the best cells may not perform as well when integrated into packs for vehicles because of the environment in which vehicles operate. This paper discusses mechanical, electrical, and thermal integration issues and vehicle interface issues that could impact the cost, life, and safety of the system. It also compares the advantages and disadvantages of using many small cells versus a few large cells and using prismatic cells versus cylindrical cells.
The ObjECTS: Framework for Integrated Assessment: Hybrid Modeling of Transportation
Kim, Son H.; Edmonds, James A.; Lurz, Joshua; Smith, Steven J.; Wise, Marshall A.
2006-09-01
Technology is a central issue for the global climate change problem, requiring analysis tools that can examine the impact of specific technologies with a long-term, global context. This paper describes the architecture of the ObjECTS-MiniCAM integrated assessment model, which implements a long-term, global model of energy, economy, agriculture, land-use, atmosphere, and climate change in a framework that allows the flexible incorporation of explicit technology detail. We describe the implementation of a ''bottom-up'' representation of the transportation sector as an illustration of this approach, in which the resulting hybrid model is fully integrated, internally consistent and theoretically compatible with the regional and global modeling framework. The analysis of the transportation sector presented here supports and clarifies the need for a comprehensive strategy promoting advanced vehicle technologies and an economy-wide carbon policy to cost-effectively reduce carbon emissions from the transportation sector in the long-term.
Path Integral Quantum Monte Carlo Study of Coupling and Proximity Effects in Superfluid Helium-4
NASA Astrophysics Data System (ADS)
Graves, Max T.
When bulk helium-4 is cooled below T = 2.18 K, it undergoes a phase transition to a superfluid, characterized by a complex wave function with a macroscopic phase and exhibits inviscid, quantized flow. The macroscopic phase coherence can be probed in a container filled with helium-4, by reducing one or more of its dimensions until they are smaller than the coherence length, the spatial distance over which order propagates. As this dimensional reduction occurs, enhanced thermal and quantum fluctuations push the transition to the superfluid state to lower temperatures. However, this trend can be countered via the proximity effect, where a bulk 3-dimensional (3d) superfluid is coupled to a low (2d) dimensional superfluid via a weak link producing superfluid correlations in the film at temperatures above the Kosterlitz-Thouless temperature. Recent experiments probing the coupling between 3d and 2d superfluid helium-4 have uncovered an anomalously large proximity effect, leading to an enhanced superfluid density that cannot be explained using the correlation length alone. In this work, we have determined the origin of this enhanced proximity effect via large scale quantum Monte Carlo simulations of helium-4 in a topologically non-trivial geometry that incorporates the important aspects of the experiments. We find that due to the bosonic symmetry of helium-4, identical particle permutations lead to correlations between contiguous spatial regions at a length scale greater than the coherence length. We show that quantum exchange plays a large role in explaining the anomalous experimental results while simultaneously showing how classical arguments fall short of this task.
Unifying scheme for generating discrete integrable systems including inhomogeneous and hybrid models
NASA Astrophysics Data System (ADS)
Kundu, Anjan
2003-10-01
A unifying scheme based on an ancestor model is proposed for generating a wide range of integrable discrete and continuum as well as inhomogeneous and hybrid models. They include in particular discrete versions of sine-Gordon, Landau-Lifshitz, nonlinear Schrödinger (NLS), derivative NLS equations, Liouville model, (non-)relativistic Toda chain, Ablowitz-Ladik model, etc. Our scheme introduces the possibility of building a novel class of integrable hybrid systems including multicomponent models like massive Thirring, discrete self-trapping, two-mode derivative NLS by combining different descendant models. We also construct inhomogeneous systems like Gaudin model including new ones like variable mass sine-Gordon, variable coefficient NLS, Ablowitz-Ladik, Toda chains, etc. keeping their flows isospectral, as opposed to the standard approach. All our models are generated from the same ancestor Lax operator (or its q?1 limit) and satisfy the classical Yang-Baxter equation sharing the same r-matrix. This reveals an inherent universality in these diverse systems, which become explicit at their action-angle level.
Microscopic Studies of Solid 4HE with Path Integral Projector Monte Carlo
NASA Astrophysics Data System (ADS)
Rossi, M.; Rota, R.; Vitali, E.; Galli, D. E.; Reatto, L.
2008-06-01
We have investigated the ground state properties of solid 4He with the Shadow Path Integral Ground State method. This exact T = 0 K projector method allows to describes quantum solids without introducing any a priori equilibrium position. We have found that the efficiency in computing off-diagonal properties in the solid phase sensibly improves when the direct sampling of permutations, in principle not required, is introduced. We have computed the exact one-body density matrix (OBDM) in large commensurate 4He crystal finding a decreasing condensate fraction with increasing imaginary time of projection, making our result not conclusive on the presence of Bose-Einstein condensation in bulk solid 4He. We can only give an upper bound of 2.5×10-8 on the condensate fraction. We have exploited the Shadow Path Integral Ground State (SPIGS) method to study also 4He crystal containing grain boundaries by computing the related surface energy and the OBDM along these defects. We have found that also highly symmetrical grain boundaries have a finite condensate fraction. We have also derived a route for the estimation of the true equilibrium concentration of vacancies x? in bulk T = 0 k solid 4He, which is shown to be finite, x? = (1.4 ± 0.1) × 10-3 at the melting density, when computed with the variational shadow wave function technique.
Harvey, J-P; Gheribi, A E; Chartrand, P
2011-08-28
The design of multicomponent alloys used in different applications based on specific thermo-physical properties determined experimentally or predicted from theoretical calculations is of major importance in many engineering applications. A procedure based on Monte Carlo simulations (MCS) and the thermodynamic integration (TI) method to improve the quality of the predicted thermodynamic properties calculated from classical thermodynamic calculations is presented in this study. The Gibbs energy function of the liquid phase of the Cu-Zr system at 1800 K has been determined based on this approach. The internal structure of Cu-Zr melts and amorphous alloys at different temperatures, as well as other physical properties were also obtained from MCS in which the phase trajectory was modeled by the modified embedded atom model formalism. A rigorous comparison between available experimental data and simulated thermo-physical properties obtained from our MCS is presented in this work. The modified quasichemical model in the pair approximation was parameterized using the internal structure data obtained from our MCS and the precise Gibbs energy function calculated at 1800 K from the TI method. The predicted activity of copper in Cu-Zr melts at 1499 K obtained from our thermodynamic optimization was corroborated by experimental data found in the literature. The validity of the amplitude of the entropy of mixing obtained from the in silico procedure presented in this work was analyzed based on the thermodynamic description of hard sphere mixtures. PMID:21895194
NASA Astrophysics Data System (ADS)
Ahn, Jeonghwan; Lee, Hoonkyung; Kwon, Yongkyung
2015-03-01
Existence of a stable commensurate structure in the second 4He layer on graphite has been a subject of intensive experimental and theoretical studies because of its implication in the possible realization of two-dimensional supersolidity. Earlier path-integral Monte Carlo (PIMC) calculations of Pierce and Manousakis predicted a stable C4/7 commensurate structure above the first-layer 4He atoms fixed at triangular lattice sites, but Corboz et al. later showed that no commensurate phase was stable when quantum dynamics of the first-layer 4He atoms was incorporated in the PIMC calculations. On the other hand, recent heat capacity measurements of Nakamura et al. provided a strong evidence for a commensurate solid in the second 4He layer over an extended density range. Motivated by this, we have performed new PIMC calculations for the second helium layer on graphite. Unlike previous PIMC calculations where a laterally-averaged one-dimensional substrate potential was used, we here employ an anisotropic 4He-graphite potential described by a sum of the 4He-C pair potentials. With this fully-corrugated substrate potential we make more accurate description of quantum dynamics of the first-layer 4He atoms and analyze its effects on the phase diagram of the second layer.
NASA Astrophysics Data System (ADS)
Bonitz, Michael; Schoof, Tim; Groth, Simon
2014-10-01
Thermodynamic properties of the homogeneous electron gas (HEG) at finite temperatures are of high importance for many systems, including dense quantum plasmas, warm dense matter or plasmas in the interior of compact stars. Recently, Restricted Path Integral Monte-Carlo data for low to moderate densities (rs = r /aB >= 1) have been presented, while the high-density regime was not accessible due to the Fermion sign problem. Here we apply the recently developed Configuration PIMC (CPIMC) method to the HEG at high densities (rs <~ 0 . 5) and low to moderate temperatures (? =kB T /EF <= 1). We demonstrate that CPIMC allows for efficient ab-initio quilibrium calculations of thermodynamic properties of highly degenerate, moderately coupled electrons. It is based on the representation of the N-particle density operator in a basis of antisymmetrized N-particle states) and does not suffer from the Fermion sign problem in the non-interacting limit. Deutsche Forschungsgemeinschaft, BO1366-9.
Path Integral Monte Carlo Study of X@C50 [X=H2, He, Ne, Ar
NASA Astrophysics Data System (ADS)
Peng, Chun; Zhang, Hong; Cheng, Xin-Lu
2013-11-01
Path integral Monte Carlo (PIMC) method is employed to study the thermal properties of the X@C50[X=H2, He, Ne, Ar] system at temperatures from 5K to 300 K. The interaction energies and probability distribution functions of one noble gas atom or H2 inside D5h-symmetry C50 are obtained. A rough sphere model is used in calculating interaction energies, as a comparison. This model gives much lower interaction energy than PIMC calculations on all X@C50, except He@C50. The PIMC method and the sphere model get nearly the same values of interaction energies on He@C50. The spatial distributions are enlarged by the increase in temperature, while the interaction energies change slowly in a wide range of temperature. Temperature is not the major reason for the stability of the system. It is impossible to trap an X atom into C50, except H2 because only the H2@C50 has positive interaction energies from the PIMC calculations.
NASA Astrophysics Data System (ADS)
Kwon, Yongkyung; Shin, Hyeondeok
2010-11-01
We have studied adsorption of H4e on the surface of a single C20 fullerene molecule using the path-integral Monte Carlo method. For a full incorporation of the surface corrugations on the molecular surface the H4e-C20 interaction is treated with a sum of empirical helium-carbon interatomic pair potentials. Radial density distributions show layer-by-layer growth of H4e , and a detailed analysis of energetics and angular density distributions reveals that the strongly bound first layer, located at a distance of ˜4.9Å from the center of the C20 molecule, is in various quantum states as the number of H4e atoms changes. This layer, when completed with 32 atoms, is found to be a solid whose structure is commensurate with the underlying molecular surface. Near the completion of the first layer we observe a finite superfluid fraction as well as a solid order at a low temperature of T=0.31K . This manifestation of supersolidity on a nanometer scale is understood to be induced by the presence of mobile vacancies.
NASA Astrophysics Data System (ADS)
Otaki, Hiroki; Ando, Koji
2015-01-01
The dielectric properties of proton(H)-deuteron(D) mixed crystals of the hydrogen-bonded material 5-Bromo-9-hydroxyphenalenone are studied using a novel path integral Monte Carlo (PIMC) method that takes account of the dipole induction effect depending on the relative proton configurations in the surrounding molecules. The induced dipole is evaluated using the fragment molecular orbital method with electron correlation included by second-order Møller-Plesset perturbation theory and long-range corrected density functional theory. The results show a greater influence of Csbnd H ⋯O intermolecular weak hydrogen bonding on the induction than for results evaluated with the Hartree-Fock method. The induction correction is incorporated into the PIMC simulations with a model Hamiltonian that consists of long-range dipolar interactions and a transverse term describing proton tunneling. The relationship between the calculated phase transition temperature and H/D mixing ratio is consistent with the experimental phase diagram, indicating that the balance between the proton tunneling and the collective ordering is appropriately described.
NASA Astrophysics Data System (ADS)
Wang, Lecheng; Xie, Daiqian
2012-08-01
We report finite temperature quantum mechanical simulations of structural and dynamical properties of ArN-CO2 clusters using a path integral Monte Carlo algorithm. The simulations are based on a newly developed analytical Ar-CO2 interaction potential obtained by fitting ab initio results to an anisotropic two-dimensional Morse/Long-range function. The calculated distributions of argon atoms around the CO2 molecule in ArN-CO2 clusters with different sizes are consistent to the previous studies of the configurations of the clusters. A first-order perturbation theory is used to quantitatively predict the CO2 vibrational frequency shift in different clusters. The first-solvation shell is completed at N = 17. Interestingly, our simulations for larger ArN-CO2 clusters showed several different structures of the argon shell around the doped CO2 molecule. The observed two distinct peaks (2338.8 and 2344.5 cm-1) in the ?3 band of CO2 may be due to the different arrangements of argon atoms around the dopant molecule.
NASA Astrophysics Data System (ADS)
Shams, Ali; Glyde, Henry
2008-03-01
We evaluate the Bose-Einstein condensate density and the superfluid fraction of bosons in a periodic external potential using Path-Integral Monte Carlo (PIMC) methods. A unit cell containing a potential well is replicated into a lattice along 1D using periodic boundary conditions. The aim is to describe bosons in a 1D optical lattice or helium confined in a periodic porous medium. The One-Body Density Matrix (OBDM) is evaluated and diagonalized to obtain the single boson natural orbitals (e.g. the condensate orbital) and the occupation of these orbitals (e.g. the condensate fraction). The superfluid density is obtained from the winding number. We investigate (1) the impact of the periodic external potential on the spatial distribution of the condensate, and (2) the correlation between localizing the condensate into separated parts and the loss of superflow along the lattice. For strongly interaction Bosons, as the well depth increases, the condensate becomes depleted in the wells (depletion by interaction). For weakly interacting bosons, as the well depth increases, the BEC is localized at the center of the wells (tight binding). In both cases, the localization of the condensate suppresses superflow leading to a superfluid-insulator cross-over. The temperature dependence is investigated and comparison with Hubbard models and experiment is made.
Superfluid response of 4He N-N 2O clusters probed by path integral Monte Carlo simulations
NASA Astrophysics Data System (ADS)
Wang, Lecheng; Xie, Daiqian; Guo, Hua; Li, Hui; Le Roy, Robert J.; Roy, Pierre-Nicholas
2011-05-01
Using an improved path integral Monte Carlo method, finite-temperature structural and dynamical properties of 4He N-N 2O clusters ( N ? 40) are investigated. The simulations employed a newly developed He-N 2O interaction potential obtained at the CCSD(T) level. Good agreement with experimental observations was obtained for the evolution of the effective rotational constant as a function of cluster size. In particular, the experimentally observed turnaround at N = 6 for the effective rotational constant B eff is attributed to filling of the "donut" ring structure around the equator of the linear impurity molecule, and a second extremum in B eff for cluster sizes near N = 10 is associated with the emergence of superfluidity of the quantum solvent. A careful comparison with properties of He N-CO 2 clusters suggests that the difference between the renormalized rotational constants of the two impurity molecules is due to the anisotropy of the solute-solvent interaction potential.
Quantum rotation of Rb2 (3 ? {u/+}) attached to HeN droplets: a path-integral Monte Carlo study
NASA Astrophysics Data System (ADS)
Rodríguez-Cantano, Rocío; Pérez de Tudela, Ricardo; López-Durán, David; González-Lezana, Tomás; Gianturco, Franco A.; Delgado-Barrio, Gerardo; Villarreal, Pablo
2013-06-01
Doped He N Rb2 (3 ? u +) systems, with N = 20 and 40, have been studied by means of a path integral Monte Carlo method at two different temperatures T = 1 K and 2 K. The impurity, Rb2, is assumed as a rigid rotor and results are compared with a previous analysis in which no rotational or translational degrees of freedom were taken into account. Quantum effects are observed to play a noticeable role accounting for the extra energy with respect to the fixed Rb2 case although differences between the two approaches do not seem to be as important as reported for some other dopants attached to helium droplets, such as OCS for example. Probability density distributions exhibit the same overall features as the non-rotating system, predicting the outer location of Rb2 with respect to the helium atoms. The stability of the two clusters under study at T = 2 K is uncertain: the energy of He20Rb2 is positive and for He40Rb2, the observed dependence on the confinements imposed on the system precludes definitive statements regarding its physical existence.
NASA Astrophysics Data System (ADS)
Tramonto, F.; Salvestrini, P.; Nava, M.; Galli, D. E.
2015-07-01
By means of the Path Integral Monte Carlo method, we have performed a detailed microscopic study of 4He nanodroplets doped with an argon ion, Ar, at K. We have computed density profiles, energies, dissociation energies, and characterized the local order around the ion for nanodroplets with a number of 4He atoms ranging from 10 to 64 and also 128. We have found the formation of a stable solid structure around the ion, a "snowball", consisting of three concentric shells in which the 4He atoms are placed at the vertices of platonic solids: the first inner shell is an icosahedron (12 atoms); the second one is a dodecahedron with 20 atoms placed on the faces of the icosahedron of the first shell; the third shell is again an icosahedron composed of 12 atoms placed on the faces of the dodecahedron of the second shell. The "magic numbers" implied by this structure, 12, 32, and 44 helium atoms, have been observed in a recent experimental study (Bartl et al., J Phys Chem A 118:8050, 2014) of these complexes; the dissociation energy curve computed in the present work shows jumps in correspondence with those found in the nanodroplets abundance distribution measured in that experiment, strengthening the agreement between theory and experiment. The same structures were predicted in Galli et al. (J Phys Chem A 115:7300, 2011) in a study regarding Na+@4He when ; a comparison between Ar+@4He and Na+@4He complexes is also presented.
NASA Astrophysics Data System (ADS)
Cuccoli, Alessandro; Macchi, Alessandro; Pedrolli, Gaia; Tognetti, Valerio; Vaia, Ruggero
1995-05-01
We consider the problem of the extrapolation of path-integral Monte Carlo (PIMC) data to infinite Trotter number P. Finite-P data, being even functions of P, have high-P dependence that is generally well described by a quadratic fit, a0+a1P-2, where a0 is the exact quantum value. However, in order to get convergence it is often necessary to run PIMC codes with rather high P values, which implies long computer times and larger statistical errors of the data. It is well known that also for harmonic systems the finite-P data are not exact; nevertheless, they can be easily calculated by Gaussian quadrature. Starting from this observation, we suggest an easy way to correct PIMC data for anharmonic systems in order to take into account the harmonic part exactly, with strong improvement of the extrapolation to P=?. Lower Trotter numbers are thus required, with the advantages of computer-time saving and much better accuracy of the extrapolated values, without any change in the PIMC code. In order to demonstrate the effectiveness of the approach, we report finite-P data processing for a single anharmonic particle, whose finite-P data are obtained by the matrix-squaring method, and for a chain of atoms with Morse interaction.
Wu, Chunxiao; Wyatt, Alexander W; Lapuk, Anna V; McPherson, Andrew; McConeghy, Brian J; Bell, Robert H; Anderson, Shawn; Haegert, Anne; Brahmbhatt, Sonal; Shukin, Robert; Mo, Fan; Li, Estelle; Fazli, Ladan; Hurtado-Coll, Antonio; Jones, Edward C; Butterfield, Yaron S; Hach, Faraz; Hormozdiari, Fereydoun; Hajirasouliha, Iman; Boutros, Paul C; Bristow, Robert G; Jones, Steven Jm; Hirst, Martin; Marra, Marco A; Maher, Christopher A; Chinnaiyan, Arul M; Sahinalp, S Cenk; Gleave, Martin E; Volik, Stanislav V; Collins, Colin C
2012-05-01
Next-generation sequencing is making sequence-based molecular pathology and personalized oncology viable. We selected an individual initially diagnosed with conventional but aggressive prostate adenocarcinoma and sequenced the genome and transcriptome from primary and metastatic tissues collected prior to hormone therapy. The histology-pathology and copy number profiles were remarkably homogeneous, yet it was possible to propose the quadrant of the prostate tumour that likely seeded the metastatic diaspora. Despite a homogeneous cell type, our transcriptome analysis revealed signatures of both luminal and neuroendocrine cell types. Remarkably, the repertoire of expressed but apparently private gene fusions, including C15orf21:MYC, recapitulated this biology. We hypothesize that the amplification and over-expression of the stem cell gene MSI2 may have contributed to the stable hybrid cellular identity. This hybrid luminal-neuroendocrine tumour appears to represent a novel and highly aggressive case of prostate cancer with unique biological features and, conceivably, a propensity for rapid progression to castrate-resistance. Overall, this work highlights the importance of integrated analyses of genome, exome and transcriptome sequences for basic tumour biology, sequence-based molecular pathology and personalized oncology. PMID:22294438
Integration of Xantrex HY-100 Hybrid Inverter with an AC Induction Wind Turbine
Corbus, D.; Newcomb, C.; Friedly, S.
2003-05-01
Several issues must be addressed before solid-state inverters can be used in wind-diesel systems with larger wind turbines. This project addresses those issues by using a commercial hybrid inverter designed for PV-diesel systems and modifying the inverter for use with an AC induction wind turbine. Another approach would have entailed building an inverter specifically for use with an AC induction wind turbine, but that was beyond the scope of this project. The inverter chosen for this project was a Xantrex HY-100, an inverter designed for PV systems. The unit consists of an inverter/rectifier bridge, a generator interface contactor, a battery charge controller, a hybrid controller, and the associated control electronics. Details of the inverter may be found in Appendix A. A twofold approach was taken to integrating the existing inverter for use with an AC induction wind turbine: 1) development of a detailed model to model both steady-state and transient behavior of the system, and 2) modification and testing of the inverter with an induction wind turbine based on the modeling results. This report describes these two tasks.
Electrocoagulation-integrated hybrid membrane processes for the treatment of tannery wastewater.
Keerthi; Vinduja, V; Balasubramanian, N
2013-10-01
Three different combinations of treatment techniques, i.e. electrocoagulation combined with microfiltration (EMR), membrane bioreactor (MBR) and electrocoagulation integrated with membrane bioreactor (hybrid MBR, (HMBR)), were analysed and compared for the treatment of tannery wastewater operated for 7 days under the constant trans-membrane pressure of 5 kPa. HMBR was found to be most suitable in performance as well as fouling reduction, with 94 % of chemical oxygen demand (COD) removal, 100 % chromium removal and 8 % improvement in percentage reduction in permeate flux compared to MBR with only 90 % COD removal and 67 % chromium removal. The effect of mixed liquor suspended solids on fouling was also investigated and was found to be insignificant. EMR was capable of elevating the flux but was not as efficient as HMBR and MBR in COD removal. Fouling reduction by HMBR was further confirmed by SEM-EDX and particle size analysis. PMID:23653316
Celik, Metin
2009-03-01
The International Safety Management (ISM) Code defines a broad framework for the safe management and operation of merchant ships, maintaining high standards of safety and environmental protection. On the other hand, ISO 14001:2004 provides a generic, worldwide environmental management standard that has been utilized by several industries. Both the ISM Code and ISO 14001:2004 have the practical goal of establishing a sustainable Integrated Environmental Management System (IEMS) for shipping businesses. This paper presents a hybrid design methodology that shows how requirements from both standards can be combined into a single execution scheme. Specifically, the Analytic Hierarchy Process (AHP) and Fuzzy Axiomatic Design (FAD) are used to structure an IEMS for ship management companies. This research provides decision aid to maritime executives in order to enhance the environmental performance in the shipping industry. PMID:19038488
NASA Technical Reports Server (NTRS)
Combi, Michael R.
2004-01-01
In order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic (MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important. At the University of Michigan we have an established base of experience and expertise in numerical simulations based on particle codes which address these physical regimes. The Principal Investigator, Dr. Michael Combi, has over 20 years of experience in the development of particle-kinetic and hybrid kinetichydrodynamics models and their direct use in data analysis. He has also worked in ground-based and space-based remote observational work and on spacecraft instrument teams. His research has involved studies of cometary atmospheres and ionospheres and their interaction with the solar wind, the neutral gas clouds escaping from Jupiter s moon Io, the interaction of the atmospheres/ionospheres of Io and Europa with Jupiter s corotating magnetosphere, as well as Earth s ionosphere. This report describes our progress during the year. The contained in section 2 of this report will serve as the basis of a paper describing the method and its application to the cometary coma that will be continued under a research and analysis grant that supports various applications of theoretical comet models to understanding the inner comae of comets (grant NAGS- 13239 from the Planetary Atmospheres program).
NSDL National Science Digital Library
David Joiner
Monte Carlo modeling refers to the solution of mathematical problems with the use of random numbers. This can include both function integration and the modeling of stochastic phenomena using random processes.
Christian Artigues; Michel Gendreau; Louis-Martin Rousseau; Adrien Vergnaud
2009-01-01
We propose exact hybrid methods based on integer linear programming and constraint programming for an integrated employee timetabling and job-shop scheduling problem. Each method we investigate uses a constraint programming (CP) formulation associated with a linear programming (LP) relaxation. Under a CP framework, the LP-relaxation is integrated into a global constraint using in addition reduced cost-based filtering techniques. We propose
Abdallah Bacha; K. Wu
1998-01-01
The newly proposed hybrid-integration technology of a nonradiative dielectric (NRD)-guide and planar structure offers an attractive alternative for designing microwave and millimeter-wave integrated circuits and systems. This paper presents an attempt with a transmission-line matrix (TLM) analysis toward accurate design and optimization of the NRD\\/microstrip-line transitions for the proposed scheme. Electrical performance of the transitions is studied with respect to
Clark, Michael A. [Harvard; Joo, Balint [JLAB; Kennedy, Anthony D. [Edinburgh; Silva, Paolo J. [Coimbra
2011-10-01
We show how the integrators used for the molecular dynamics step of the Hybrid Monte Carlo algorithm can be further improved. These integrators not only approximately conserve some Hamiltonian H but conserve exactly a nearby shadow Hamiltonian H~. This property allows for a new tuning method of the molecular dynamics integrator and also allows for a new class of integrators (force-gradient integrators) which is expected to reduce significantly the computational cost of future large-scale gauge field ensemble generation.
Andreas W. Schell; Günter Kewes; Tim Schröder; Janik Wolters; Thomas Aichele; Oliver Benson
2011-01-01
Integrated quantum optical hybrid devices consist of fundamental constituents such as single emitters and tailored photonic nanostructures. A reliable fabrication method requires the controlled deposition of active nanoparticles on arbitrary nanostructures with highest precision. Here, we describe an easily adaptable technique that employs picking and placing of nanoparticles with an atomic force microscope combined with a confocal setup. In this
Paris-Sud XI, Université de
whereas the objective of employee timetabling is to maximize employee satisfaction (or to minimize labor process would allow to balance production costs and employee satisfaction in a better way. HoweverSolving an integrated employee timetabling and job-shop scheduling problem via hybrid branch
Joaquín Espinosa-García; Cipriano Rangel; Marta Navarrete; José C. Corchado
2004-01-01
A computational approach to calculating potential energy surfaces for reactive systems is presented and tested. This hybrid approach is based on integrated methods where calculations for a small model system are performed by using analytical potential energy surfaces, and for the real system by using molecular orbital or molecular mechanics methods. The method is tested on a hydrogen abstraction reaction
Reisslein, Martin
Integrating emerging topics through online team design in a hybrid communication networks course in the introductory communication networks course at Arizona State University, the authors have developed an online Abstract An important challenge in the introductory communication networks course in electrical
Raymond S. T. Lee; James N. K. Liu
2000-01-01
We present an automatic and integrated neural network-based tropical cyclone (TC) identification and track mining system. The proposed system consists of two main modules: 1) TC pattern identification system using neural oscillatory elastic graph matching model; and 2) TC track mining system using hybrid radial basis function network with time difference and structural learning algorithm. For system evaluation, 120 TC
Electric-drive tractability indicator integrated in hybrid electric vehicle tachometer
Tamai, Goro; Zhou, Jing; Weslati, Feisel
2014-09-02
An indicator, system and method of indicating electric drive usability in a hybrid electric vehicle. A tachometer is used that includes a display having an all-electric drive portion and a hybrid drive portion. The all-electric drive portion and the hybrid drive portion share a first boundary which indicates a minimum electric drive usability and a beginning of hybrid drive operation of the vehicle. The indicated level of electric drive usability is derived from at least one of a percent battery discharge, a percent maximum torque provided by the electric drive, and a percent electric drive to hybrid drive operating cost for the hybrid electric vehicle.
NASA Astrophysics Data System (ADS)
Shams, Ali A.; Glyde, H. R.
2009-06-01
We evaluate the Bose-Einstein condensate density and the superfluid fraction of bosons in a periodic external potential using path-integral Monte Carlo methods. The periodic lattice consists of a cubic cell containing a potential well that is replicated along one dimension using periodic boundary conditions. The aim is to describe bosons in a one-dimensional optical lattice or helium confined in a periodic porous medium. The one-body density matrix is evaluated and diagonalized numerically to obtain the single boson natural orbitals and the occupation of these orbitals. The condensate fraction is obtained as the fraction of bosons in the orbital that has the highest occupation. The superfluid density is obtained from the winding number. From the condensate orbital and superfluid fraction, we investigate (1) the impact of the periodic external potential on the spatial distribution of the condensate, and (2) the correlation of localizing the condensate into separated parts and the loss of superflow along the lattice. For high-density systems, as the well depth increases, the condensate becomes depleted in the wells and confined to the plateaus between successive wells, as in pores between necks in a porous medium. For low-density systems, as the well depth increases the BEC is localized at the center of the wells (tight binding) and depleted between the wells. In both cases, the localization of the condensate suppresses superflow leading to a superfluid-insulator crossover. The impact of the external potential on the temperature dependence of the superfluidity is also investigated. The external potential suppresses the superfluid fraction at all temperatures, with a superfluid fraction significantly less than one at low temperature. The addition of an external potential does not, however, significantly reduce the transition temperature.
NASA Astrophysics Data System (ADS)
Tramonto, F.; Salvestrini, P.; Nava, M.; Galli, D. E.
2015-01-01
By means of the exact Path Integral Monte Carlo method we have performed a detailed microscopic study of $^4$He nanodroplets doped with an argon ion, Ar$^+$, at $T=0.5$ K. We have computed density profiles, energies, dissociation energies and characterized the local order around the ion for nanodroplets with a number of 4He atoms ranging from 10 to 64 and also 128. We have found the formation of a stable solid structure around the ion, a "snowball", consisting of 3 concentric shells in which the 4He atoms are placed on at the vertices of platonic solids: the first inner shell is an icosahedron (12 atoms); the second one is a dodecahedron with 20 atoms placed on the faces of the icosahedron of the first shell; the third shell is again an icosahedron composed of 12 atoms placed on the faces of the dodecahedron of the second shell. The "magic numbers" implied by this structure, 12, 32 and 44 helium atoms, have been observed in a recent experimental study [Bartl et al, J. Phys. Chem. A 118, 2014] of these complexes; the dissociation energy curve computed in the present work shows jumps in correspondence with those found in the nanodroplets abundance distribution measured in that experiment, strengthening the agreement between theory and experiment. The same structures were predicted in Ref. [Galli et al, J. Phys. Chem. A 115, 2011] in a study regarding Na$^+$@$^4$He$_n$ when n>30; a comparison between Ar$^+$@$^4$He$_n$ and Na$^+$@$^4$He$_n$ complexes is also presented.
SiGe Integrated Circuit/SQUID Hybrid Cryogenic Multiplexer for Superconducting Bolometer Array
NASA Astrophysics Data System (ADS)
Prêle, D.; Voisin, F.; Oger, R.; Chapron, C.; Bréelle, E.; Piat, M.
2009-12-01
The development of large superconducting bolometer (Transition Edge Sensor: TES) arrays requires ultra low noise amplification and multiplexing electronics. The use of a first transducer stage such as a SQUID (Superconducting QUantum Interference Device) allows ultimate performance in terms of noise. However, the linearization of the SQUID characteristic requires low noise amplification. Furthermore, to realize a time domain multiplexer with SQUIDs, switched biasing is also needed. We have designed an Integrated Circuit (IC) in standard BiCMOS SiGe technology for the readout and the control of a SQUID multiplexer. It includes a low noise amplifier with multiplexed inputs, switched current sources for SQUIDs, and digital circuit for the addressing with only one room temperature clock signal. We have successfully tested this integrated circuit down to 2 K. To validate the operation of a SQUID multiplexer controlled by this SiGe cryogenic IC, we have developed a 2×2 SQUID hybrid demonstrator. It consists of four commercial SQUIDs connected to a SiGe IC.
First application close measurements applying the new hybrid integrated MEMS spectrometer
NASA Astrophysics Data System (ADS)
Grüger, Heinrich; Pügner, Tino; Knobbe, Jens; Schenk, Harald
2013-05-01
Grating spectrometers have been designed in many different configurations. Now potential high volume applications ask for extremely miniaturized and low cost systems. By the use of integrated MEMS (micro electro mechanical systems) scanning grating devices a less expensive single detector can be used in the NIR instead of the array detectors required for fixed grating systems. Meanwhile the design of a hybrid integrated MEMS scanning grating spectrometer has been drawn. The MEMS device was fabricated in the Fraunhofer IPMS own clean room facility. This chip is mounted on a small circuit board together with the detector and then stacked with spacer and mirror substrate. The spectrometer has been realized by stacking several planar substrates by sophisticated mounting technologies. The spectrometer has been designed for the 950nm - 1900nm spectral range and 9nm spectral resolution with organic matter analysis in mind. First applications are considered in the food quality analysis and food processing technology. As example for the use of a spectrometer with this performance the grill process of steak was analyzed. Similar measurement would be possible on dairy products, vegetables or fruit. The idea is a mobile spectrometer for in situ and on site analysis applications in or attached to a host system providing processing, data access and input-output capabilities, disregarding this would be a laptop, tablet, smart phone or embedded platform.
40-Gb/s All-Optical Processing Systems Using Hybrid Photonic Integration Technology
NASA Astrophysics Data System (ADS)
Kehayas, Efstratios; Tsiokos, Dimitris; Bakopoulos, Paraskevas; Apostolopoulos, Dimitris; Petrantonakis, Dimitrios; Stampoulidis, Leontios; Poustie, Alistair; McDougall, Rob; Maxwell, Graeme; Liu, Yong; Zhang, Shaoxian; Dorren, Harmen J. S.; Seoane, Jorge; van Holm-Nielsen, Pablo; Jeppesen, Palle; Avramopoulos, Hercules
2006-12-01
This paper presents an experimental performance characterization of all-optical subsystems at 40 Gb/s using interconnected hybrid integrated all-optical semiconductor optical amplifier (SOA) Mach Zehnder interferometer (MZI) gates and flip-flop prototypes. It was shown that optical gates can be treated as generic switching elements and, when efficiently interconnected, can form larger and more functional network subsystems. Specifically, this paper reports on all-optical subsystems capable of performing on-the-fly packet clock recovery, 3R regeneration, label/payload separation, and packet routing using the wavelength domain. The all-optical subsystems are capable of operating with packet-mode traffic and are suitable for all-optical label-switched and self-routed network nodes. The intelligent functionality offered, combined with the compactness and stability of the optical gates, verifies the potential that all-optical technology can find application in future data-centric networks with efficient and dynamic bandwidth utilization. This paper also reports on the latest photonic integration breakthroughs as a potential migration path for reducing fabrication cost by developing photonic systems-on-chip utilizing multiple SOA-MZI optical gates on a single chip.
NASA Astrophysics Data System (ADS)
Zhang, Xingyu; Hosseini, Amir; Subbaraman, Harish; Wang, Shiyi; Zhan, Qiwen; Luo, Jingdong; Jen, Alex K.; Chung, Chi-jui; Yan, Hai; Pan, Zeyu; Nelson, Robert L.; Lee, Charles Y.; Chen, Ray T.
2015-03-01
The detection and measurement of electromagnetic fields have attracted significant amounts of attention in recent years. Traditional electronic electromagnetic field sensors use large active conductive probes which perturb the field to be measured and also make the devices bulky. In order to address these problems, integrated photonic electromagnetic field sensors have been developed, in which an optical signal is modulated by an RF signal collected by a miniaturized antenna. In this work, we design, fabricate and characterize a compact, broadband and highly sensitive integrated photonic electromagnetic field sensor based on a silicon-organic hybrid modulator driven by a bowtie antenna. The large electro-optic (EO) coefficient of organic polymer, the slow-light effects in the silicon slot photonic crystal waveguide (PCW), and the broadband field enhancement provided by the bowtie antenna, are all combined to enhance the interaction of microwaves and optical waves, enabling a high EO modulation efficiency and thus a high sensitivity. The modulator is experimentally demonstrated with a record-high effective in-device EO modulation efficiency of r33=1230pm/V. Modulation response up to 40GHz is measured, with a 3-dB bandwidth of 11GHz. The slot PCW has an interaction length of 300?m, and the bowtie antenna has an area smaller than 1cm2. The bowtie antenna in the device is experimentally demonstrated to have a broadband characteristics with a central resonance frequency of 10GHz, as well as a large beam width which enables the detection of electromagnetic waves from a large range of incident angles. The sensor is experimentally demonstrated with a minimum detectable electromagnetic power density of 8.4mW/m2 at 8.4GHz, corresponding to a minimum detectable electric field of 2.5V/m and an ultra-high sensitivity of 0.000027V/m Hz-1/2 ever demonstrated. To the best of our knowledge, this is the first silicon-organic hybrid device and also the first PCW device used for the photonic detection of electromagnetic waves. Finally, we propose some future work, including a Teraherz wave sensor based on antenna-coupled electrooptic polymer filled plasmonic slot waveguide, as well as a fully packaged and tailgated device.
NASA Astrophysics Data System (ADS)
Griesheimer, D. P.; Gill, D. F.; Nease, B. R.; Sutton, T. M.; Stedry, M. H.; Dobreff, P. S.; Carpenter, D. C.; Trumbull, T. H.; Caro, E.; Joo, H.; Millman, D. L.
2014-06-01
MC21 is a continuous-energy Monte Carlo radiation transport code for the calculation of the steady-state spatial distributions of reaction rates in three-dimensional models. The code supports neutron and photon transport in fixed source problems, as well as iterated-fission-source (eigenvalue) neutron transport problems. MC21 has been designed and optimized to support large-scale problems in reactor physics, shielding, and criticality analysis applications. The code also supports many in-line reactor feedback effects, including depletion, thermal feedback, xenon feedback, eigenvalue search, and neutron and photon heating. MC21 uses continuous-energy neutron/nucleus interaction physics over the range from 10-5 eV to 20 MeV. The code treats all common neutron scattering mechanisms, including fast-range elastic and non-elastic scattering, and thermal- and epithermal-range scattering from molecules and crystalline materials. For photon transport, MC21 uses continuous-energy interaction physics over the energy range from 1 keV to 100 GeV. The code treats all common photon interaction mechanisms, including Compton scattering, pair production, and photoelectric interactions. All of the nuclear data required by MC21 is provided by the NDEX system of codes, which extracts and processes data from EPDL-, ENDF-, and ACE-formatted source files. For geometry representation, MC21 employs a flexible constructive solid geometry system that allows users to create spatial cells from first- and second-order surfaces. The system also allows models to be built up as hierarchical collections of previously defined spatial cells, with interior detail provided by grids and template overlays. Results are collected by a generalized tally capability which allows users to edit integral flux and reaction rate information. Results can be collected over the entire problem or within specific regions of interest through the use of phase filters that control which particles are allowed to score each tally. The tally system has been optimized to maintain a high level of efficiency, even as the number of edit regions becomes very large.
Bio-hybrid integrated system for wide-spectrum solar energy harvesting
NASA Astrophysics Data System (ADS)
Martin, Kathleen; Erdman, Matthew; Quintana, Hope; Shelnutt, John; Nogan, John; Swartzentruber, B.; Martinez, Julio; Lavrova, Olga; Busani, Tito
2014-03-01
An integrated hybrid photovoltaic-thermoelectric system has been developed using multiple layers of organic photosensitizers on inorganic semiconductors in order to efficiently convert UV-visible and IR energy into electricity. The hot anode of n-type ZnO nanowires was fabricated using a thermal process on pre-seeded layer and results to be crystalline with a transmittance up to 92 % and a bandgap of 3.32 eV. The visible-UV light-active organic layer was deposited between the anode and cathode at room temperature using a layer-by-layer deposition onto ITO and ZnO and Bi2Te3 nanowires from aqueous solution. The organic layer, a cooperative binary ionic (CBI) solid is composed of oppositely charged porphyrin metal (Zn(II) and Sn(IV)(OH-)2) derivatives that are separately water soluble, but when combined form a virtually insoluble solid. The electron donor/acceptor properties (energy levels, band gaps) of the solid can be controlled by the choice of metals and the nature of the peripheral substituent groups of the porphyrin ring. The highly thermoelectric structure, which acts as a cold cathode, is composed of p-type Bi2Te3 nanowires with a thermoelectric efficiency (ZT) between ~0.7 to 1, values that are twice that expected for bulk Bi2Te3. Efficiency of the integrated device, was found to be 35 at 0.2 suns illumination and thermoelectric properties are enhanced by the charge transfer between the CBI and the Bi2Te3 is presented in terms of photo- and thermogenerated current and advantages of the low cost fabrication process is discussed.
NASA Technical Reports Server (NTRS)
Rothmann, Elizabeth; Dugan, Joanne Bechta; Trivedi, Kishor S.; Mittal, Nitin; Bavuso, Salvatore J.
1994-01-01
The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. The Hybrid Automated Reliability Predictor (HARP) tutorial provides insight into HARP modeling techniques and the interactive textual prompting input language via a step-by-step explanation and demonstration of HARP's fault occurrence/repair model and the fault/error handling models. Example applications are worked in their entirety and the HARP tabular output data are presented for each. Simple models are presented at first with each succeeding example demonstrating greater modeling power and complexity. This document is not intended to present the theoretical and mathematical basis for HARP.
Jeongwoo Han; Cam Nguyen
2005-01-01
A new compact low-cost sampling mixer with internal local strobe-pulse generator for (carrierless) ultra-wideband (UWB) applications, especially for sub-sampling of UWB video pulse signals, is presented along with detailed design information. The sampler employs a double-sided planar structure to facilitate interface with the strobe-pulse generator and the baseband circuit without using wire connections or air bridges, enabling hybrid microwave integrated-circuit
Hyunjae Yoo; Seung-Ki Sul; Yongho Park; Jongchan Jeong
2008-01-01
In this paper, system integration and power-flow management algorithms for a four-wheel-driven series hybrid electric vehicle (HEV) having multiple power sources composed of a diesel-engine-based generator, lead acid battery bank, and supercapacitor bank are presented. The super-capacitor is utilized as a short-term energy storage device to meet the dynamic performance of the vehicle, while the battery is utilized as a
F. G. Bogdanov; D. D. Karkashadze; R. G. Jobava; E. Yavolovskaya; N. Bondarenko
2008-01-01
Based on modified mirror image method, an equivalent model of layered glass antenna structure is suggested and applied to consider finite-sized glass antennas integrated into a full car model. The hybrid MoM is derived and validated by comparison of simulated results with those obtained by measurements on complex finite-sized grid antenna model placed near a metallic plate. Some EMC characteristics
Kyeong-Sik Shin; Young-Hwan Kim; Kyeong-Kap Paek; Jung-Ho Park; Eun-Gyeong Yang; Tae-Song Kim; Ji-Yoon Kang; Byeong-Kwon Ju
2006-01-01
A new integrated fluorescence-detection hybrid device with a photodiode and an organic light-emitting diode (OLED), and its characteristics are presented. To detect the fluorescent signal using OLED as a light source, a finger-type photodiode with low parasitic resistance was designed, which utilizes the side depletion region in the p+n junction. In addition, OLED was designed to have the peak intensity
Monte Carlo Neutrino Oscillations
James P. Kneller; Gail C. McLaughlin
2005-09-29
We demonstrate that the effects of matter upon neutrino propagation may be recast as the scattering of the initial neutrino wavefunction. Exchanging the differential, Schrodinger equation for an integral equation for the scattering matrix S permits a Monte Carlo method for the computation of S that removes many of the numerical difficulties associated with direct integration techniques.
NASA Astrophysics Data System (ADS)
Del Maestro, Adrian; Affleck, Ian
2010-08-01
Harmonically trapped ultracold atoms and H4e in nanopores provide different experimental realizations of bosons in one dimension, motivating the search for a more complete theoretical understanding of their low-energy properties. Worm algorithm path-integral quantum Monte Carlo results for interacting bosons restricted to the one dimensional continuum are compared to the finite temperature and system size predictions of Luttinger-liquid theory. For large system sizes at low temperature, excellent agreement is obtained after including the leading irrelevant interactions in the Hamiltonian which are determined explicitly.
NASA Astrophysics Data System (ADS)
Cruz, Anthony; López, Gustavo E.
2014-04-01
By using path integral Monte Carlo simulations coupled to Replica Exchange algorithms, various phases of (p-H2)7 physically adsorbed on a model graphite surface were identified at low temperatures. At T=0.5 K, the expected superfluid phase was observed for flat and slightly corrugated surfaces. At intermediate and high corrugations, a "supersolid" phase in C7/16 registry and a solid phase in C1/3 registry were observed, respectively. At higher temperatures, the superfluid is converted to a fluid and the "supersolid" to a solid.
NASA Astrophysics Data System (ADS)
Cramer, S. N.; Roussin, R. W.
1981-11-01
A Monte Carlo analysis of a time-dependent neutron and secondary gamma-ray integral experiment on a thick concrete and steel shield is presented. The energy range covered in the analysis is 15-2 MeV for neutron source energies. The multigroup MORSE code was used with the VITAMIN C 171-36 neutron-gamma-ray cross-section data set. Both neutron and gamma-ray count rates and unfolded energy spectra are presented and compared, with good general agreement, with experimental results.
Asselineau, Charles-Alexis; Zapata, Jose; Pye, John
2015-06-01
A stochastic optimisation method adapted to illumination and radiative heat transfer problems involving Monte-Carlo ray-tracing is presented. A solar receiver shape optimisation case study illustrates the advantages of the method and its potential: efficient receivers are identified using a moderate computational cost. PMID:26072868
Kevin M. Warren; Andrew L. Sternberg; Robert A. Weller; Mark P. Baze; Lloyd W. Massengill; Robert A. Reed; Marcus H. Mendenhall; Ronald D. Schrimpf
2008-01-01
Monte-Carlo radiation transport code is coupled with SPICE circuit level simulation to identify regions of single event upset vulnerability in an SEU hardened flip-flop, as well as predict single event upset cross sections and on-orbit soft error rates under static and dynamic operating conditions.
1-D EQUILIBRIUM DISCRETE DIFFUSION MONTE CARLO
T. EVANS; ET AL
2000-08-01
We present a new hybrid Monte Carlo method for 1-D equilibrium diffusion problems in which the radiation field coexists with matter in local thermodynamic equilibrium. This method, the Equilibrium Discrete Diffusion Monte Carlo (EqDDMC) method, combines Monte Carlo particles with spatially discrete diffusion solutions. We verify the EqDDMC method with computational results from three slab problems. The EqDDMC method represents an incremental step toward applying this hybrid methodology to non-equilibrium diffusion, where it could be simultaneously coupled to Monte Carlo transport.
Hybrid materials science: a promised land for the integrative design of multifunctional materials.
Nicole, Lionel; Laberty-Robert, Christel; Rozes, Laurence; Sanchez, Clément
2014-06-21
For more than 5000 years, organic-inorganic composite materials created by men via skill and serendipity have been part of human culture and customs. The concept of "hybrid organic-inorganic" nanocomposites exploded in the second half of the 20th century with the expansion of the so-called "chimie douce" which led to many collaborations between a large set of chemists, physicists and biologists. Consequently, the scientific melting pot of these very different scientific communities created a new pluridisciplinary school of thought. Today, the tremendous effort of basic research performed in the last twenty years allows tailor-made multifunctional hybrid materials with perfect control over composition, structure and shape. Some of these hybrid materials have already entered the industrial market. Many tailor-made multiscale hybrids are increasingly impacting numerous fields of applications: optics, catalysis, energy, environment, nanomedicine, etc. In the present feature article, we emphasize several fundamental and applied aspects of the hybrid materials field: bioreplication, mesostructured thin films, Lego-like chemistry designed hybrid nanocomposites, and advanced hybrid materials for energy. Finally, a few commercial applications of hybrid materials will be presented. PMID:24866174
Integration of rapid DNA hybridization and capillary zone electrophoresis using bidirectional
Santiago, Juan G.
The second is bidirectional ITP which uses a strong counter-migrating pH gradient across a cationic ITP based hybridization to the extraction and detection of 16S ribosomal RNA (rRNA) of E. coli in human addresses the issue of a relatively high background signal in ITP based hybridization assays by effecting
Buettgenback, T.H. (California Inst. of Tech., Pasadena, CA (United States). Div. of Physics)
1993-10-01
The hybrid antenna discussed here is defined as a dielectric lens-antenna as a special case of an extended hemispherical dielectric lens that is operated in the diffraction limited regime. It is a modified version of the planar antenna on a lens scheme developed by Rutledge. The dielectric lens-antenna is fed by a planar-structure antenna, which is mounted on the flat side of the dielectric lens-antenna using it as a substrate, and the combination is termed a hybrid antenna. Beam pattern and aperture efficiency measurements were made at millimeter and submillimeter wavelengths as a function of extension of the hemispherical lens and different lens sizes. An optimum extension distance is found experimentally and numerically for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved. At 115 GHz the aperture efficiency was measured to be (76 [+-] 6)% for a diffraction limited beam with sidelobes below [minus]17 dB. Results of a single hybrid antenna with an integrated Superconductor-Insulator-Superconductor (SIS) detector and a broad-band matching structure at submillimeter wavelengths are presented. The hybrid antenna is diffraction limited, space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal plane heterodyne receiver arrays.
NASA Astrophysics Data System (ADS)
Lesiuk, Micha?; Moszynski, Robert
2014-12-01
In this paper, which constitutes the first part of the series, we consider calculation of two-center Coulomb and hybrid integrals over Slater-type orbitals. General formulas for these integrals are derived with no restrictions on the values of the quantum numbers and nonlinear parameters. Direct integration over the coordinates of one of the electrons leaves us with the set of overlaplike integrals which are evaluated by using two distinct methods. The first one is based on the transformation to the ellipsoidal coordinates system and the second utilizes a recursive scheme for consecutive increase of the angular momenta in the integrand. In both methods simple one-dimensional numerical integrations are used in order to avoid severe digital erosion connected with the straightforward use of the alternative analytical formulas. It is discussed that the numerical integration does not introduce a large computational overhead since the integrands are well-behaved functions, calculated recursively with decent speed. Special attention is paid to the numerical stability of the algorithms. Applicability of the resulting scheme over a large range of the nonlinear parameters is tested on examples of the most difficult integrals appearing in the actual calculations including, at most, 7 i -type functions (l =6 ).
Primordial black hole seeding from hybrid inflation : the direct integration approach
Giguere, Alexis
2013-01-01
We examine the notion that supermassive black holes at the centre of galaxies, such as the Milky Way, could have been seeded in the early universe by the mechanisms of hybrid inflation. Using luminosity data, we estimate ...
ITS Version 3.0: The Integrated TIGER Series of coupled electron/photon Monte Carlo transport codes
Halbleib, J.A.; Kensek, R.P.; Valdez, G.D.; Mehlhorn, T.A. [Sandia National Labs., Albuquerque, NM (United States); Seltzer, S.M.; Berger, M.J. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Ionizing Radiation Div.
1993-06-01
ITS is a powerful and user-friendly software package permitting state-of-the-art Monte Carlo solution of linear time-independent coupled electron/photon radiation transport problems, with or without the presence of macroscopic electric and magnetic fields. It combines operational simplicity and physical accuracy in order to provide experimentalists and theorists alike with a method for the routine but rigorous solution of sophisticated radiation transport problems. Flexibility of construction permits tailoring of the codes to specific applications and extension of code capabilities to more complex applications through simple update procedures.
NASA Astrophysics Data System (ADS)
Leclerc, Melanie R.; Côté, Patrice; Duchesne, François; Bastien, Pierre; Hernandez, Olivier; Colonna d'Istria, Pierre; Demers, Mathieu; Girard, Marc; Savard, Maxime; Lemieux, Dany; Thibault, Simon; Brousseau, Denis
2014-08-01
A polarimeter, to observe exoplanets in the visible and infrared, was built for the "Observatoire du Mont Mégantic" (OMM) to replace an existing instrument and reach 10-6 precision, a factor 100 improvement. The optical and mechanical designs are presented, with techniques used to precisely align the optical components and rotation axes to achieve the targeted precision. A photo-elastic modulator (PEM) and a lock-in amplifier are used to measure the polarization. The typical signal is a high DC superimposed to a very faint sinusoidal oscillation. Custom electronics was developed to measure the AC and DC amplitudes, and characterization results are presented.
NASA Astrophysics Data System (ADS)
Buchowiecki, Marcin; Vaní?ek, Ji?í
2013-11-01
The Feynman path integral approach for computing equilibrium isotope effects and isotope fractionation corrects the approximations made in standard methods, although at significantly increased computational cost. We describe an accelerated path integral approach based on three ingredients: the fourth-order Takahashi-Imada factorization of the path integral, thermodynamic integration with respect to mass, and centroid virial estimators for relevant free energy derivatives. While the first ingredient speeds up convergence to the quantum limit, the second and third improve statistical convergence. The combined method is applied to compute the equilibrium constants for isotope exchange reactions H+D?H+HDand H+D?2HD.
Buchowiecki, Marcin
2013-01-01
The Feynman path integral approach for computing equilibrium isotope effects and isotope fractionation corrects the approximations made in standard methods, although at significantly increased computational cost. We describe an accelerated path integral approach based on three ingredients: the fourth- order Takahashi-Imada factorization of the path integral, thermodynamic integration with respect to mass, and centroid virial estimators for relevant free energy derivatives. While the frst ingredient speeds up convergence to the quantum limit, the second and third improve statistical convergence. The combined method is applied to compute the equilibrium constants for isotope exchange reactions H2+D=H+HD and H2+D2=2HD.
Riboldi, M.; Chen, G. T. Y.; Baroni, G.; Paganetti, H.; Seco, J.
2015-01-01
We have designed a simulation framework for motion studies in radiation therapy by integrating the anthropomorphic NCAT phantom into a 4D Monte Carlo dose calculation engine based on DPM. Representing an artifact-free environment, the system can be used to identify class solutions as a function of geometric and dosimetric parameters. A pilot dynamic conformal study for three lesions (~ 2.0 cm) in the right lung was performed (70 Gy prescription dose). Tumor motion changed as a function of tumor location, according to the anthropomorphic deformable motion model. Conformal plans were simulated with 0 to 2 cm margin for the aperture, with additional 0.5 cm for beam penumbra. The dosimetric effects of intensity modulated radiotherapy (IMRT) vs. conformal treatments were compared in a static case. Results show that the Monte Carlo simulation framework can model tumor tracking in deformable anatomy with high accuracy, providing absolute doses for IMRT and conformal radiation therapy. A target underdosage of up to 3.67 Gy (lower lung) was highlighted in the composite dose distribution mapped at exhale. Such effects depend on tumor location and treatment margin and are affected by lung deformation and ribcage motion. In summary, the complexity in the irradiation of moving targets has been reduced to a controlled simulation environment, where several treatment options can be accurately modeled and quantified The implemented tools will be utilized for extensive motion study in lung/liver irradiation. PMID:19044324
NASA Astrophysics Data System (ADS)
Beccara, S. A.; Fornasini, P.
2008-05-01
The distributions of interatomic distances of the first four coordination shells of copper and their leading cumulants have been determined by a path-integral Monte Carlo calculation on a many-body potential model, in the temperature range of 4 300 K. The asymmetry of the distance distribution, measured by the third cumulant, is much larger for the first shell than for the outer shells. The mean value of the distance between neighboring atoms is given for each shell by the first cumulant of the distribution. This allowed us to test a well-known method of estimating the thermal expansion of each shell from the second and third cumulants of its distribution. This method gave values smaller by 40% for the first shell and much smaller for all outer shells.
NASA Astrophysics Data System (ADS)
Li, Hui; Blinov, Nicholas; Roy, Pierre-Nicholas; Le Roy, Robert J.
2009-04-01
Path-integral Monte Carlo simulations of the ?3 vibrational band origin frequency shifts of CO2 in (He)n clusters for n =1-40 show that although only the asymmetric-stretch mode of CO2 is being excited, the effect of the associated change in the average value of Q1 cannot be ignored. When this fourth degree of freedom is taken into account, the resulting predicted vibrational frequency shifts are in excellent agreement with experiment across this whole range of cluster size. It is also shown that the quality of predictions obtained from simulations on a given potential energy surface can depend significantly on the choice of the analytic function used to represent it.
Hybrid information privacy system: integration of chaotic neural network and RSA coding
Ming-Kai Hsu; Jeff Willey; Ting N. Lee; Harold H. Szu
2005-01-01
Electronic mails are adopted worldwide; most are easily hacked by hackers. In this paper, we purposed a free, fast and convenient hybrid privacy system to protect email communication. The privacy system is implemented by combining private security RSA algorithm with specific chaos neural network encryption process. The receiver can decrypt received email as long as it can reproduce the specified
Uhde, Britta; Andreas Hahn, W; Griess, Verena C; Knoke, Thomas
2015-08-01
Multi-criteria decision analysis (MCDA) is a decision aid frequently used in the field of forest management planning. It includes the evaluation of multiple criteria such as the production of timber and non-timber forest products and tangible as well as intangible values of ecosystem services (ES). Hence, it is beneficial compared to those methods that take a purely financial perspective. Accordingly, MCDA methods are increasingly popular in the wide field of sustainability assessment. Hybrid approaches allow aggregating MCDA and, potentially, other decision-making techniques to make use of their individual benefits and leading to a more holistic view of the actual consequences that come with certain decisions. This review is providing a comprehensive overview of hybrid approaches that are used in forest management planning. Today, the scientific world is facing increasing challenges regarding the evaluation of ES and the trade-offs between them, for example between provisioning and regulating services. As the preferences of multiple stakeholders are essential to improve the decision process in multi-purpose forestry, participatory and hybrid approaches turn out to be of particular importance. Accordingly, hybrid methods show great potential for becoming most relevant in future decision making. Based on the review presented here, the development of models for the use in planning processes should focus on participatory modeling and the consideration of uncertainty regarding available information. PMID:25896820
INTEGRATING THE DESIGN AND RELIABILITY ASSESSMENT OF A HYBRID PV-THERMAL MICROCONCENTRATOR SYSTEM
of Technology, Austria. ABSTRACT The Australian National University (ANU) is developing a new hybrid CPV of the active cooling system. IEC 62108 tests procedures have been analysed in order to verify and extend their suitability for active cooling systems. A modified and extended test sequence is proposed to assess actively-cooled
Chakrabortty, S; Sen, M; Pal, P
2014-03-01
A simulation software (ARRPA) has been developed in Microsoft Visual Basic platform for optimization and control of a novel membrane-integrated arsenic separation plant in the backdrop of absence of such software. The user-friendly, menu-driven software is based on a dynamic linearized mathematical model, developed for the hybrid treatment scheme. The model captures the chemical kinetics in the pre-treating chemical reactor and the separation and transport phenomena involved in nanofiltration. The software has been validated through extensive experimental investigations. The agreement between the outputs from computer simulation program and the experimental findings are excellent and consistent under varying operating conditions reflecting high degree of accuracy and reliability of the software. High values of the overall correlation coefficient (R (2)?=?0.989) and Willmott d-index (0.989) are indicators of the capability of the software in analyzing performance of the plant. The software permits pre-analysis, manipulation of input data, helps in optimization and exhibits performance of an integrated plant visually on a graphical platform. Performance analysis of the whole system as well as the individual units is possible using the tool. The software first of its kind in its domain and in the well-known Microsoft Excel environment is likely to be very useful in successful design, optimization and operation of an advanced hybrid treatment plant for removal of arsenic from contaminated groundwater. PMID:24288068
Hou, Chao; Lang, Xing-You; Han, Gao-Feng; Li, Ying-Qi; Zhao, Lei; Wen, Zi; Zhu, Yong-Fu; Zhao, Ming; Li, Jian-Chen; Lian, Jian-She; Jiang, Qing
2013-01-01
Nanoarchitectured electroactive materials can boost rates of Li insertion/extraction, showing genuine potential to increase power output of Li-ion batteries. However, electrodes assembled with low-dimensional nanostructured transition metal oxides by conventional approach suffer from dramatic reductions in energy capacities owing to sluggish ion and electron transport kinetics. Here we report that flexible bulk electrodes, made of three-dimensional bicontinuous nanoporous Cu/MnO2 hybrid and seamlessly integrated with Cu solid current collector, substantially optimizes Li storage behavior of the constituent MnO2. As a result of the unique integration of solid/nanoporous hybrid architecture that simultaneously enhances the electron transport of MnO2, facilitates fast ion diffusion and accommodates large volume changes on Li insertion/extraction of MnO2, the supported MnO2 exhibits a stable capacity of as high as ~1100?mA h g?1 for 1000 cycles, and ultrahigh charge/discharge rates. It makes the environmentally friendly and low-cost electrode as a promising anode for high-performance Li-ion battery applications. PMID:24096928
P(VDF-TrFE) ferroelectrics: Integration in hybrid and thin-film memories
Michael O. Thompson; Connie Lew; Johan Carlsson; Per Brahms
2008-01-01
Poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) is a promising ferroelectric polymer with potential application for both high density hybrid and printable low-cost memory. This talk will review the structural, polarization, and electrical properties of this polymer ferroelectric, identifying the key challenges and opportunities at the system level from both processing and architectural standpoints. The unique hysteresis and time-response properties permit fabrication of large
Fluorescent In Situ Hybridization to Detect Transgene Integration into Plant Genomes
NASA Astrophysics Data System (ADS)
Schwarzacher, Trude
Fluorescent chromosome analysis technologies have advanced our understanding of genome organization during the last 30 years and have enabled the investigation of DNA organization and structure as well as the evolution of chromosomes. Fluorescent chromosome staining allows even small chromosomes to be visualized, characterized by their composition and morphology, and counted. Aneuploidies and polyploidies can be established for species, breeding lines, and individuals, including changes occurring during hybridization or tissue culture and transformation protocols. Fluorescent in situ hybridization correlates molecular information of a DNA sequence with its physical location on chromosomes and genomes. It thus allows determination of the physical position of sequences and often is the only means to determine the abundance and distribution of DNA sequences that are difficult to map with any other molecular method or would require segregation analysis, in particular multicopy or repetitive DNA. Equally, it is often the best way to establish the incorporation of transgenes, their numbers, and physical organization along chromosomes. This chapter presents protocols for probe and chromosome preparation, fluorescent in situ hybridization, chromosome staining, and the analysis of results.
NASA Astrophysics Data System (ADS)
Topper, Robert Q.; Zhang, Qi; Liu, Yi-Ping; Truhlar, Donald G.
1993-03-01
Converged quantum mechanical vibrational-rotational partition functions and free energies are calculated using realistic potential energy surfaces for several chalcogen dihydrides (H2O, D2O, H2S, H2Se) over a wide range of temperatures (600-4000 K). We employ an adaptively optimized Monte Carlo integration scheme for computing vibrational-rotational partition functions by the Fourier path-integral method. The partition functions and free energies calculated in this way are compared to approximate calculations that assume the separation of vibrational motions from rotational motions. In the approximate calculations, rotations are treated as those of a classical rigid rotator, and vibrations are treated by perturbation theory methods or by the harmonic oscillator model. We find that the perturbation theory treatments yield molecular partition functions which agree closely overall (within ˜7%) with the fully coupled accurate calculations, and these treatments reduce the errors by about a factor of 2 compared to the independent-mode harmonic oscillator model (with errors of ˜16%). These calculations indicate that vibrational anharmonicity and mode-mode coupling effects are significant, but that they may be treated with useful accuracy by perturbation theory for these molecules. The quantal free energies for gaseous water agree well with previously available approximate values for this well studied molecule, and similarly accurate values are also presented for the less well studied D2O, H2S, and H2Se.
NASA Technical Reports Server (NTRS)
Richardson, Erin; Hays, M. J.; Blackwood, J. M.; Skinner, T.
2014-01-01
The Liquid Propellant Fragment Overpressure Acceleration Model (L-FOAM) is a tool developed by Bangham Engineering Incorporated (BEi) that produces a representative debris cloud from an exploding liquid-propellant launch vehicle. Here it is applied to the Core Stage (CS) of the National Aeronautics and Space Administration (NASA) Space Launch System (SLS launch vehicle). A combination of Probability Density Functions (PDF) based on empirical data from rocket accidents and applicable tests, as well as SLS specific geometry are combined in a MATLAB script to create unique fragment catalogues each time L-FOAM is run-tailored for a Monte Carlo approach for risk analysis. By accelerating the debris catalogue with the BEi blast model for liquid hydrogen / liquid oxygen explosions, the result is a fully integrated code that models the destruction of the CS at a given point in its trajectory and generates hundreds of individual fragment catalogues with initial imparted velocities. The BEi blast model provides the blast size (radius) and strength (overpressure) as probabilities based on empirical data and anchored with analytical work. The coupling of the L-FOAM catalogue with the BEi blast model is validated with a simulation of the Project PYRO S-IV destruct test. When running a Monte Carlo simulation, L-FOAM can accelerate all catalogues with the same blast (mean blast, 2 s blast, etc.), or vary the blast size and strength based on their respective probabilities. L-FOAM then propagates these fragments until impact with the earth. Results from L-FOAM include a description of each fragment (dimensions, weight, ballistic coefficient, type and initial location on the rocket), imparted velocity from the blast, and impact data depending on user desired application. LFOAM application is for both near-field (fragment impact to escaping crew capsule) and far-field (fragment ground impact footprint) safety considerations. The user is thus able to use statistics from a Monte Carlo set of L-FOAM catalogues to quantify risk for a multitude of potential CS destruct scenarios. Examples include the effect of warning time on the survivability of an escaping crew capsule or the maximum fragment velocities generated by the ignition of leaking propellants in internal cavities.
Arora, Bhavna; Mohanty, Binayak P; McGuire, Jennifer T
2015-04-15
Predicting and controlling the concentrations of redox-sensitive elements are primary concerns for environmental remediation of contaminated sites. These predictions are complicated by dynamic flow processes as hydrologic variability is a governing control on conservative and reactive chemical concentrations. Subsurface heterogeneity in the form of layers and lenses further complicates the flow dynamics of the system impacting chemical concentrations including redox-sensitive elements. In response to these complexities, this study investigates the role of heterogeneity and hydrologic processes in an effective parameter upscaling scheme from the column to the landfill scale. We used a Markov chain Monte Carlo (MCMC) algorithm to derive upscaling coefficients for hydrological and geochemical parameters, which were tested for variations across heterogeneous systems (layers and lenses) and interaction of flow processes based on the output uncertainty of dominant biogeochemical concentrations at the Norman Landfill site, a closed municipal landfill with prevalent organic and trace metal contamination. The results from MCMC analysis indicated that geochemical upscaling coefficients based on effective concentration ratios incorporating local heterogeneity across layered and lensed systems produced better estimates of redox-sensitive biogeochemistry at the field scale. MCMC analysis also suggested that inclusion of hydrological parameters in the upscaling scheme reduced the output uncertainty of effective mean geochemical concentrations by orders of magnitude at the Norman Landfill site. This was further confirmed by posterior density plots of the scaling coefficients that revealed unimodal characteristics when only geochemical processes were involved, but produced multimodal distributions when hydrological parameters were included. The multimodality again suggests the effect of heterogeneity and lithologic variability on the distribution of redox-sensitive elements at the Norman Landfill site. PMID:25644839
NASA Astrophysics Data System (ADS)
Adams, A. D.; Johnson, Greg A.; Jolivet, Noel D.; Metschuleit, Jeff L.
1992-07-01
When testing infrared readouts, detector-readout hybrid assemblies, or focal plane arrays (FPAs), performance optimization is usually limited to adjustment of biases or clock rails, or subtle changes in readout timing. These generally result in global changes to the characteristics of the entire array rather than affecting individual pixels and channels. Using a scanning system that incorporates per channel gain normalization and a redundant time delay and integrate (TDI) architecture in the readout, pixels can be enhanced or deselected using an on- chip static RAM according to user-defined criteria resulting in improved uniformity of performance. A series of tests can be run automatically that evaluate each pixel's behavior at the readout or the hybrid level. When compared to or compiled against array-wide averages or system specifications, a map of dead or degraded pixels is created, and the timing necessary to either normalize each channel from a gain standpoint or mask out individual pixels is applied to the device under test. This technique has been successfully applied to 480 X 6 (120 X 4 X 6 in TDI) scanning architectures in both InSb and HgCdTe systems as well as multiple-chip and dual-band configurations. This paper describes a methodology and details how readout devices were screened and selected for hybridization and FPA build. The chip architecture and control timing is discussed to show how normalization and deselection was accomplished with a minimum of clock lines involved. A software utility is presented that allowed easy graphical interface to the user for manipulating the functions of the device. Algorithms for optimizing performance are then discussed and evaluated. Trade-offs made in optimizing one parameter against another are analyzed. Finally, results are presented demonstrating improved performance, customized by pixel to suit application specifications.
A. A. AZIMI; B. HOOSHYARI; N. MEHRDADI; G. H. NABI BIDHENDI
Nowadays, innovative processes especially processes with integrated growth (combined attached and suspended growth) such as moving bed biofilm reactor (MBBR) and integrated fixed film activated Sludge (IFAS) are being used successfully for new construction and upgrading existing wastewater treatment plants. Increasing the hydraulic capacity, COD and nutrients removal from the effluent are the two main targets of applying these processes.
NASA Astrophysics Data System (ADS)
Buchowiecki, Marcin
2014-03-01
The TI/PIMC method proposed in Buchowiecki (2012) [1] for computing the temperature dependence of the equilibrium constant is used with the Takahashi-Imada approximation of the path integral. It is shown that the Takahashi-Imada approximation allows faster convergence than primitive approximation. The method is used to calculate the equilibrium constant of the deuterium exchange reaction NH+HD?NHD+H. The substituent effect was simulated by changing mass of one of the hydrogen atoms in the NH molecule.
Monte Carlo sampling from the quantum state space. II
NASA Astrophysics Data System (ADS)
Seah, Yi-Lin; Shang, Jiangwei; Khoon Ng, Hui; Nott, David John; Englert, Berthold-Georg
2015-04-01
High-quality random samples of quantum states are needed for a variety of tasks in quantum information and quantum computation. Searching the high-dimensional quantum state space for a global maximum of an objective function with many local maxima or evaluating an integral over a region in the quantum state space are but two exemplary applications of many. These tasks can only be performed reliably and efficiently with Monte Carlo methods, which involve good samplings of the parameter space in accordance with the relevant target distribution. We show how the Markov-chain Monte Carlo method known as Hamiltonian Monte Carlo, or hybrid Monte Carlo, can be adapted to this context. It is applicable when an efficient parameterization of the state space is available. The resulting random walk is entirely inside the physical parameter space, and the Hamiltonian dynamics enable us to take big steps, thereby avoiding strong correlations between successive sample points while enjoying a high acceptance rate. We use examples of single and double qubit measurements for illustration.
Monte Carlo sampling from the quantum state space. II
Yi-Lin Seah; Jiangwei Shang; Hui Khoon Ng; David John Nott; Berthold-Georg Englert
2015-04-27
High-quality random samples of quantum states are needed for a variety of tasks in quantum information and quantum computation. Searching the high-dimensional quantum state space for a global maximum of an objective function with many local maxima or evaluating an integral over a region in the quantum state space are but two exemplary applications of many. These tasks can only be performed reliably and efficiently with Monte Carlo methods, which involve good samplings of the parameter space in accordance with the relevant target distribution. We show how the Markov-chain Monte Carlo method known as Hamiltonian Monte Carlo, or hybrid Monte Carlo, can be adapted to this context. It is applicable when an efficient parameterization of the state space is available. The resulting random walk is entirely inside the physical parameter space, and the Hamiltonian dynamics enable us to take big steps, thereby avoiding strong correlations between successive sample points while enjoying a high acceptance rate. We use examples of single and double qubit measurements for illustration.
NASA Astrophysics Data System (ADS)
Symeonidis, Vasileios; Karniadakis, George Em
2006-10-01
We propose new schemes for integrating the stochastic differential equations of dissipative particle dynamics (DPD) in simulations of dilute polymer solutions. The hybrid DPD models consist of hard potentials that describe the microscopic dynamics of polymers and soft potentials that describe the mesoscopic dynamics of the solvent. In particular, we develop extensions to the velocity-Verlet and Lowe's approaches - two representative DPD time-integrators - following a subcycling procedure whereby the solvent is advanced with a timestep much larger than the one employed in the polymer time-integration. The introduction of relaxation parameters allows optimization studies for accuracy while maintaining the low computational complexity of standard DPD algorithms. We demonstrate through equilibrium simulations that a 10-fold gain in efficiency can be obtained with the time-staggered algorithms without loss of accuracy compared to the non-staggered schemes. We then apply the new approach to investigate the scaling response of polymers in equilibrium as well as the dynamics of ?-phage DNA molecules subjected to shear.
NASA Astrophysics Data System (ADS)
Chen, Po-Chiang; Ishikawa, Fumiaki N.; Chang, Hsiao-Kang; Ryu, Koungmin; Zhou, Chongwu
2009-03-01
A novel hybrid chemical sensor array composed of individual In2O3 nanowires, SnO2 nanowires, ZnO nanowires, and single-walled carbon nanotubes with integrated micromachined hotplates for sensitive gas discrimination was demonstrated. Key features of our approach include the integration of nanowire and carbon nanotube sensors, precise control of the sensor temperature using the micromachined hotplates, and the use of principal component analysis for pattern recognition. This sensor array was exposed to important industrial gases such as hydrogen, ethanol and nitrogen dioxide at different concentrations and sensing temperatures, and an excellent selectivity was obtained to build up an interesting 'smell-print' library of these gases. Principal component analysis of the sensing results showed great discrimination of those three tested chemicals, and in-depth analysis revealed clear improvement of selectivity by the integration of carbon nanotube sensors. This nanoelectronic nose approach has great potential for detecting and discriminating between a wide variety of gases, including explosive ones and nerve agents.
NASA Astrophysics Data System (ADS)
Sima, Felix; Wu, Dong; Xu, Jian; Midorikawa, Katsumi; Sugioka, Koji
2015-03-01
We propose herein the "ship-in-a-bottle" integration of three-dimensional (3D) polymeric sinusoidal ridges inside photosensitive glass microfluidic channel by a hybrid subtractive - additive femtosecond laser processing method. It consists of Femtosecond Laser Assisted Wet Etching (FLAE) of a photosensitive Foturan glass followed by Two-Photon Polymerization (TPP) of a SU-8 negative epoxy-resin. Both subtractive and additive processes are carried out using the same set-up with the change of laser focusing objective only. A 522 nm wavelength of the second harmonic generation from an amplified femtosecond Yb-fiber laser (FCPA µJewel D-400, IMRA America, 1045 nm; pulse width 360 fs, repetition rate 200 kHz) was employed for irradiation. The new method allows lowering the size limit of 3D objects created inside channels to smaller details down to the dimensions of a cell, and improve the structure stability. Sinusoidal periodic patterns and ridges are of great use as base scaffolds for building up new structures on their top or for modulating cell migration, guidance and orientation while created interspaces can be exploited for microfluidic applications. The glass microchannel offers robustness and appropriate dynamic flow conditions for cellular studies while the integrated patterns are reducing the size of structure to the level of cells responsiveness. Taking advantage of the ability to directly fabricate 3D complex shapes, both glass channels and polymeric integrated patterns enable us to 3D spatially design biochips for specific applications.
Homodyne laser Doppler vibrometer on silicon-on-insulator with integrated 90 degree optical hybrids.
Li, Yanlu; Baets, Roel
2013-06-01
A miniaturized homodyne laser Doppler vibrometer (LDV) with a compact 90° optical hybrid is experimentally demonstrated on a CMOS compatible silicon-on-insulator (SOI) platform. Optical components on this platform usually have inadequate suppressions of spurious reflections, which significantly influence the performance of the LDV. Numerical compensation methods are implemented to effectively decrease the impact of these spurious reflections. With the help of these compensation methods, measurements for both super-half-wavelength and sub-half-wavelength vibrations are demonstrated. Results show that the minimal detectable velocity is around 1.2 ?m/s. PMID:23736586
NASA Astrophysics Data System (ADS)
Cicak, K.; Andrews, R. W.; Yu, P.-L.; Peterson, R. W.; Purdy, T. P.; Burns, P. S.; Regal, C. A.; Lehnert, K. W.; Simmonds, R. W.
2015-03-01
Macroscopic high-stress silicon nitride membranes can be implemented as ultra-high-quality-factor mechanical resonators operating in the quantum regime with average phonon occupancy below one quantum. Mechanical motion of these resonators can be engineered to simultaneously couple both to (THz) light in free-space optical cavities and to microwave (GHz) fields in superconducting circuits. Exploiting this parametric coupling to realize quantum information transfer between these domains entails construction of devices with challenging requirements. These devices must integrate the membranes with superconducting circuits operating at cryogenic temperatures in proximity of free space optical photons while meeting demands for various quantum and coupling requirements. Here we show how to construct such ``hybrid quantum devices'' by microfabricating and assembling chip-based structures that can be inserted into high-finesse optical cavities compatible with low temperatures. We include an overview of recent fabrication improvements of membranes mechanically isolated from environment by phononic band-gap crystals.
Serge M. Gisler; Saranya Kittanakom; Daniel Fuster; Victoria Wong; Mia Bertic; Tamara Radanovic; Randy A. Hall; Heini Murer; Jurg Biber; Daniel Markovich; Orson W. Moe; Igor Stagljar
2008-01-01
PDZ-binding motifs are found in the C-terminal tails of numerous integral membrane proteins where they medi- ate specific protein-protein interactions by binding to PDZ-containing proteins. Conventional yeast two-hybrid screens have been used to probe protein-protein interac- tions of these soluble C termini. However, to date no in vivo technology has been available to study interactions between the full-length integral membrane
Quantum thermodynamics of (H2)x@C60 [x=1-2]: A path integral Monte Carlo study
NASA Astrophysics Data System (ADS)
Cruz, Anthony; López, Gustavo E.
2012-04-01
The thermodynamic properties of H2 and (H2)2 inside C60 were computed using the path integral formalism. In accordance with experimental data, H2@C60 is thermodynamically stable in a wide range of temperatures due to energetic factors. Variations in the molecular hydrogen-fullerene interaction energy were considered in order to increase the stability of the monomeric system. For (H2)2@C60 no stable states were observed in the temperature range studied or in any reasonable modification in the molecular hydrogen-fullerene interaction parameter. Modification of the attractive part of the molecular hydrogen-fullerene interaction stabilized the dimeric system.
Electronic integration of fuel cell and battery system in novel hybrid vehicle
NASA Astrophysics Data System (ADS)
Fisher, Peter; Jostins, John; Hilmansen, Stuart; Kendall, Kevin
2012-12-01
The objective of this work was to integrate a lithium ion battery pack, together with its management system, into a hydrogen fuel cell drive train contained in a lightweight city car. Electronic units were designed to link the drive train components using conventional circuitry. These were built, tested and shown to perform according to the design. These circuits allowed start-up of battery management system, motor controller, fuel cell warm-up and torque monitoring. After assembling the fuel cell and battery in the vehicle, full system tests were performed. Analysis of results from vehicle demonstrations showed operation was satisfactory. The conclusion was that the electronic integration was successful, but the design needed optimisation and fine tuning. Eight vehicles were then fitted with the electronically integrated fuel cell-battery power pack. Trials were then started to test the integration more fully, with a duration of 12 months from 2011 to 2012 in the CABLED project.
Chiang, C C; Kennell, J C; Wanner, L A; Lambowitz, A M
1994-01-01
The Mauriceville and Varkud mitochondrial plasmids of Neurospora spp. are closely related, small circular DNAs that propagate via an RNA intermediate and reverse transcription. Although the plasmids ordinarily replicate autonomously, they can also integrate into mitochondrial DNA (mtDNA), yielding defective mtDNAs that in some cases cause senescence. To investigate the integration mechanism, we analyzed four cases in which the Varkud plasmid integrated into the mitochondrial small rRNA gene, three in wild-type subcultures and one in a senescent mutant. Our analysis suggests that the integrations occurred by the plasmid reverse transcriptase template switching between the plasmid transcript and internal sequences in the mitochondrial small rRNA to yield hybrid cDNAs that circularized and recombined homologously with the mtDNA. The integrated plasmid sequences are transcribed, presumably from the mitochondrial small rRNA promoters, resulting in hybrid RNAs containing the 5' segment of the mitochondrial small rRNA linked head-to-tail to the full-length plasmid transcript. Analysis of additional senescent mutants revealed three cases in which the plasmid used the same mechanism to integrate at other locations in the mtDNA. In these cases, circular variant plasmids that had incorporated a mitochondrial tRNA or tRNA-like sequence by template switching integrated by homologous recombination at the site of the corresponding tRNA or tRNA-like sequence in mtDNA. This simple integration mechanism involving template switching to generate a hybrid cDNA that integrates homologously could have been used by primitive retroelements prior to the acquisition of a specialized integration machinery. Images PMID:7523850
Clark, M. A. [Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138 (United States); Joo, Balint [Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Kennedy, A. D. [Tait Institute and SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Silva, P. J. [Centro de Fisica Computacional, Universidade de Coimbra (Portugal)
2011-10-01
We show how the integrators used for the molecular dynamics step of the Hybrid Monte Carlo algorithm can be further improved. These integrators not only approximately conserve some Hamiltonian H but conserve exactly a nearby shadow Hamiltonian H-tilde. This property allows for a new tuning method of the molecular dynamics integrator and also allows for a new class of integrators (force-gradient integrators) which is expected to reduce significantly the computational cost of future large-scale gauge field ensemble generation.
NASA Astrophysics Data System (ADS)
Wilson, Robert H.; Vishwanath, Karthik; Mycek, Mary-Ann
2009-02-01
Monte Carlo (MC) simulations are considered the "gold standard" for mathematical description of photon transport in tissue, but they can require large computation times. Therefore, it is important to develop simple and efficient methods for accelerating MC simulations, especially when a large "library" of related simulations is needed. A semi-analytical method involving MC simulations and a path-integral (PI) based scaling technique generated time-resolved reflectance curves from layered tissue models. First, a zero-absorption MC simulation was run for a tissue model with fixed scattering properties in each layer. Then, a closed-form expression for the average classical path of a photon in tissue was used to determine the percentage of time that the photon spent in each layer, to create a weighted Beer-Lambert factor to scale the time-resolved reflectance of the simulated zero-absorption tissue model. This method is a unique alternative to other scaling techniques in that it does not require the path length or number of collisions of each photon to be stored during the initial simulation. Effects of various layer thicknesses and absorption and scattering coefficients on the accuracy of the method will be discussed.
Quantum Gibbs ensemble Monte Carlo
Fantoni, Riccardo, E-mail: rfantoni@ts.infn.it [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Calle Larga S. Marta DD2137, I-30123 Venezia (Italy); Moroni, Saverio, E-mail: moroni@democritos.it [DEMOCRITOS National Simulation Center, Istituto Officina dei Materiali del CNR and SISSA Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34136 Trieste (Italy)
2014-09-21
We present a path integral Monte Carlo method which is the full quantum analogue of the Gibbs ensemble Monte Carlo method of Panagiotopoulos to study the gas-liquid coexistence line of a classical fluid. Unlike previous extensions of Gibbs ensemble Monte Carlo to include quantum effects, our scheme is viable even for systems with strong quantum delocalization in the degenerate regime of temperature. This is demonstrated by an illustrative application to the gas-superfluid transition of {sup 4}He in two dimensions.
Navarro, Julio A
1990-01-01
-Controlled Oscillators and Switchable 8z Tunable CPW-Slotline Filters. (December 1990) Julio Angel Navarro, B. S. , Texas ASM University Chair of Advisory Committee: Dr. Kai Chang A Gunn device has been integrated with a notch antenna to create a bias tuned active... antenna. This design uses a coplanar waveguide (CPW) resonator and a stepped-notch antenna with bias tuning to achieve a bandwidth of 275 MHz cen- tered at 9. 33 GHz with a power output of 14. 2+1. 5 dBm. A Gunn and a varactor diode have been integrated...
Breen, Matthew; Jouquand, Sophie; Renier, Corinne; Mellersh, Cathryn S.; Hitte, Christophe; Holmes, Nigel G.; Chéron, Angélique; Suter, Nicola; Vignaux, Françoise; Bristow, Anna E.; Priat, Catherine; McCann, E.; André, Catherine; Boundy, Sam; Gitsham, Paul; Thomas, Rachael; Bridge, Wendy L.; Spriggs, Helen F.; Ryder, Ed J.; Curson, Alistair; Sampson, Jeff; Ostrander, Elaine A.; Binns, Matthew M.; Galibert, Francis
2001-01-01
We present here the first fully integrated, comprehensive map of the canine genome, incorporating detailed cytogenetic, radiation hybrid (RH), and meiotic information. We have mapped a collection of 266 chromosome-specific cosmid clones, each containing a microsatellite marker, to all 38 canine autosomes by fluorescence in situ hybridization (FISH). A 1500-marker RH map, comprising 1078 microsatellites, 320 dog gene markers, and 102 chromosome-specific markers, has been constructed using the RHDF5000-2 whole-genome radiation hybrid panel. Meiotic linkage analysis was performed, with at least one microsatellite marker from each dog autosome on a panel of reference families, allowing one meiotic linkage group to be anchored to all 38 dog autosomes. We present a karyotype in which each chromosome is identified by one meiotic linkage group and one or more RH groups. This updated integrated map, containing a total of 1800 markers, covers >90% of the dog genome. Positional selection of anchor clones enabled us, for the first time, to orientate nearly all of the integrated groups on each chromosome and to evaluate the extent of individual chromosome coverage in the integrated genome map. Finally, the inclusion of 320 dog genes into this integrated map enhances existing comparative mapping data between human and dog, and the 1000 mapped microsatellite markers constitute an invaluable tool with which to perform genome scanning studies on pedigrees of interest. PMID:11591656
Guan, Binbin; Scott, Ryan P; Qin, Chuan; Fontaine, Nicolas K; Su, Tiehui; Ferrari, Carlo; Cappuzzo, Mark; Klemens, Fred; Keller, Bob; Earnshaw, Mark; Yoo, S J B
2014-01-13
We demonstrate free-space space-division-multiplexing (SDM) with 15 orbital angular momentum (OAM) states using a three-dimensional (3D) photonic integrated circuit (PIC). The hybrid device consists of a silica planar lightwave circuit (PLC) coupled to a 3D waveguide circuit to multiplex/demultiplex OAM states. The low excess loss hybrid device is used in individual and two simultaneous OAM states multiplexing and demultiplexing link experiments with a 20 Gb/s, 1.67 b/s/Hz quadrature phase shift keyed (QPSK) signal, which shows error-free performance for 379,960 tested bits for all OAM states. PMID:24514976
Tan, Wee Chong
2012-07-16
It is well known that thermally evaporated a-As2S3 thin films are prone to oxidation when exposed to an ambient environment. These As2O3 crystals are a major source of scattering loss in sub-micron optical integrated circuits. Magnetron sputtering a...
A time dependent signal of DNA hybridization from CMOS chip integrated with CNT network
Seok Hyang Kim; Jun-Myung Woo; Jung Woo Ko; Jae Heung Lim; Jin Hong Ahn; Young June Park
2010-01-01
A fully CMOS integrated carbon nanotube (CNT) sensor array platform that consists of an 8×8 array of unitary CNT elements has been designed and fabricated. For digital conversion of the analog voltage of CNT sensor elements, a correlated double sampling (CDS) type Successive Approximation Register (SAR) Analog\\/Digital converter has been used. The chip has been applied to sense the DNA
Using Integrated Course Design to Build Student Communities of Practice in a Hybrid Course
ERIC Educational Resources Information Center
Fayne, Harriet R.
2009-01-01
In this article, the author describes how she used integrated course design to design a course that would help special education teachers satisfy the "Highly Qualified Teacher" (HQT) requirement established by No Child Left Behind (NCLB) in the area of English/language arts. The approach she chose was based on principles advanced by Fink in…
ERIC Educational Resources Information Center
Kamruzzaman, M.
2014-01-01
This study reports an action research undertaken at Queensland University of Technology. It evaluates the effectiveness of the integration of geographic information systems (GIS) within the substantive domains of an existing land use planning course in 2011. Using student performance, learning experience survey, and questionnaire survey data, it…
A hybrid numerical-asymptotic boundary integral method for high-frequency acoustic scattering
I. G. Graham; V. P. Smyshlyaev
2006-01-01
Received: date \\/ Revised: date Abstract We propose a new robust method for the computation of scattering of high-frequency acoustic plane waves by smooth convex objects in 2D. We formulate this problem by the direct boundary integral method, using the classical combined potential approach. By exploiting the known asymptotics of the solution, we devise particular expansions, valid in various zones
Design of embedded controller using hybrid systems for integrated building systems
A. Yahiaoui; JLM Hensen; L. Soethout; Paassen van AHC
2006-01-01
The design of controllers for integrated building systems has been traditionally carried out using basic techniques validated frequently by simulation. However, the demands on occupants' comfort, safety and energy consumption increase speedily as the current controllers used in buildings are not efficient and enough flexible to be adapted to any changes. To investigate such issues, this paper focuses mainly on
Integrated hybrid silicon DFB laser-EAM array using quantum well intermixing
Bowers, John
of California, Santa Barbara, California 93106, USA 2 Photonics Technology Labs, Intel Corporation, Santa Clara, California 95054, USA *siddharth@ece.ucsb.edu Abstract: We demonstrate multiple bandgap integration dissertation, Department of Electrical and Computer Engineering, University of California, Santa Barbara. June
Fazal U. Syed; Ming L. Kuang; Matt Smith; Shunsuke Okubo; Hao Ying
2009-01-01
With the increased emphasis on improving fuel economy and reducing emissions, hybrid electric vehicles (HEVs) have emerged as very strong candidates to achieve these goals. The power-split hybrid system, which is a complex hybrid powertrain, exhibits great potential to improve fuel economy by determining the most efficient regions for engine operation and thereby high-voltage (HV) battery operation to achieve overall
Benchmarking the OLGA lower-hybrid full-wave code for a future integration with ALOHA
NASA Astrophysics Data System (ADS)
Preinhaelter, J.; Hillairet, J.; Urban, J.
2014-02-01
The ALOHA [1] code is frequently used as a standard to solve the coupling of lower hybrid grills to the plasma. To remove its limitations on the linear density profile, homogeneous magnetic field and the fully decoupled fast and slow waves in the determination of the plasma surface admittance, we exploit the recently developed efficient full wave code OLGA [2]. There is simple connection between these two codes, namely, the plasma surface admittances used in ALOHA-2D can be expressed as the slowly varying parts of the coupling element integrands in OLGA and the ALOHA coupling elements are then linear combinations of OLGA coupling elements. We developed AOLGA module (subset of OLGA) for ALOHA. An extensive benchmark has been performed. ALOHA admittances differ from AOLGA results mainly for N?in the inaccessible region but the coupling elements differ only slightly. We compare OLGA and ALOHA for a simple 10-waveguide grill operating at 3.7 GHz and the linear density profile as it is used in ALOHA. Hence we can detect pure effects of fast and slow waves coupling on grill efficiency. The effects are weak for parameters near the optimum coupling and confirm the ALOHA results validity. We also compare the effect of the plasma surface density and the density gradient on the grill coupling determined by OLGA and ALOHA.
Tabernacka, Agnieszka; Zborowska, Ewa; Lebkowska, Maria; Borawski, Maciej
2014-01-15
A two-stage waste air treatment system, consisting of hybrid bioreactors (modified bioscrubbers) and a biofilter, was used to treat waste air containing chlorinated ethenes - trichloroethylene (TCE) and tetrachloroethylene (PCE). The bioreactor was operated with loadings in the range 0.46-5.50gm(-3)h(-1) for TCE and 2.16-9.02gm(-3)h(-1) for PCE. The biofilter loadings were in the range 0.1-0.97gm(-3)h(-1) for TCE and 0.2-2.12gm(-3)h(-1) for PCE. Under low pollutant loadings, the efficiency of TCE elimination was 23-25% in the bioreactor and 54-70% in the biofilter. The efficiency of PCE elimination was 44-60% in the bioreactor and 50-75% in the biofilter. The best results for the bioreactor were observed one week after the pollutant loading was increased. However, the process did not stabilize. In the next seven days contaminant removal efficiency, enzymatic activity and biomass content were all diminished. PMID:24316808
Integrated thermal and energy management of plug-in hybrid electric vehicles
NASA Astrophysics Data System (ADS)
Shams-Zahraei, Mojtaba; Kouzani, Abbas Z.; Kutter, Steffen; Bäker, Bernard
2012-10-01
In plug-in hybrid electric vehicles (PHEVs), the engine temperature declines due to reduced engine load and extended engine off period. It is proven that the engine efficiency and emissions depend on the engine temperature. Also, temperature influences the vehicle air-conditioner and the cabin heater loads. Particularly, while the engine is cold, the power demand of the cabin heater needs to be provided by the batteries instead of the waste heat of engine coolant. The existing energy management strategies (EMS) of PHEVs focus on the improvement of fuel efficiency based on hot engine characteristics neglecting the effect of temperature on the engine performance and the vehicle power demand. This paper presents a new EMS incorporating an engine thermal management method which derives the global optimal battery charge depletion trajectories. A dynamic programming-based algorithm is developed to enforce the charge depletion boundaries, while optimizing a fuel consumption cost function by controlling the engine power. The optimal control problem formulates the cost function based on two state variables: battery charge and engine internal temperature. Simulation results demonstrate that temperature and the cabin heater/air-conditioner power demand can significantly influence the optimal solution for the EMS, and accordingly fuel efficiency and emissions of PHEVs.
Hybrid Integration of End-to-End Optical Interconnects on Printed Circuit Boards
Zhaoran Rena Huang; Daniel Guidotti; Lixi Wan; Yin-Jung Chang; Jianjun Yu; Jin Liu; Hung-Fei Kuo; Gee-Kung Chang; Fuhan Liu; Rao R. Tummala
2007-01-01
This paper discusses the integration of an end-to-end optical interconnect testbed on printed circuit boards using inexpensive off-the-shelf, bare die, optoelectronic components. We developed a process for efficient and simultaneous in-plane optical coupling between edge emitting laser and waveguides, and between photodetector and waveguide. We demonstrated an optically smooth buffer layer separating the printed circuit layer from the optical transport
A hybrid numerical-asymptotic boundary integral method for high-frequency acoustic scattering
V. Domínguez; I. G. Graham; V. P. Smyshlyaev
2007-01-01
We propose a new robust method for the computation of scattering of high-frequency acoustic plane waves by smooth convex objects\\u000a in 2D. We formulate this problem by the direct boundary integral method, using the classical combined potential approach.\\u000a By exploiting the known asymptotics of the solution, we devise particular expansions, valid in various zones of the boundary,\\u000a which express the
John J. Mahmarian
2007-01-01
A natural extension of current imaging paradigms for diagnosing coronary artery disease may well be the integration of CT\\u000a with myocardial perfusion single-photon CT (SPECT). Although there is a wealth of clinical information regarding the utility\\u000a of SPECT, the value of CT in the cardiology arena has only recently been explored. CT has the advantage of detecting coronary\\u000a atherosclerosis at
NASA Astrophysics Data System (ADS)
Yang, Wei; Hall, Trevor J.
2013-12-01
The Internet is entering an era of cloud computing to provide more cost effective, eco-friendly and reliable services to consumer and business users. As a consequence, the nature of the Internet traffic has been fundamentally transformed from a pure packet-based pattern to today's predominantly flow-based pattern. Cloud computing has also brought about an unprecedented growth in the Internet traffic. In this paper, a hybrid optical switch architecture is presented to deal with the flow-based Internet traffic, aiming to offer flexible and intelligent bandwidth on demand to improve fiber capacity utilization. The hybrid optical switch is capable of integrating IP into optical networks for cloud-based traffic with predictable performance, for which the delay performance of the electronic module in the hybrid optical switch architecture is evaluated through simulation.
High quality proton beams from hybrid integrated laser-driven ion acceleration systems
NASA Astrophysics Data System (ADS)
Sinigardi, Stefano; Turchetti, Giorgio; Rossi, Francesco; Londrillo, Pasquale; Giove, Dario; De Martinis, Carlo; Bolton, Paul R.
2014-03-01
We consider a hybrid acceleration scheme for protons where the laser generated beam is selected in energy and angle and injected into a compact linac, which raises the energy from 30 to 60 MeV. The laser acceleration regime is TNSA and the energy spectrum is determined by the cutoff energy and proton temperature. The dependence of the spectrum on the target properties and the incidence angle is investigated with 2D PIC simulations. We base our work on widely available technologies and on laser with a short pulse, having in mind a facility whose cost is approximately 15 M€. Using a recent experiment as the reference, we choose the laser pulse and target so that the energy spectrum obtained from the 3D PIC simulation is close to the one observed, whose cutoff energy was estimated to be over 50 MeV. Laser accelerated protons in the TNSA regime have wide energy spectrum and broad divergence. In this paper we compare three transport lines, designed to perform energy selection and beam collimation. They are based on a solenoid, a quadruplet of permanent magnetic quadrupoles and a chicane. To increase the maximum available energy, which is actually seen as an upper limit due to laser properties and available targets, we propose to inject protons into a small linac for post-acceleration. The number of selected and injected protons is the highest with the solenoid and lower by one and two orders of magnitude with the quadrupoles and the chicane respectively. Even though only the solenoid enables achieving to reach a final intensity at the threshold required for therapy with the highest beam quality, the other systems will be very likely used in the first experiments. Realistic start-to-end simulations, as the ones reported here, are relevant for the design of such experiments.
Discrete Diffusion Monte Carlo for grey Implicit Monte Carlo simulations.
Densmore, J. D. (Jeffery D.); Urbatsch, T. J. (Todd J.); Evans, T. M. (Thomas M.); Buksas, M. W. (Michael W.)
2005-01-01
Discrete Diffusion Monte Carlo (DDMC) is a hybrid transport-diffusion method for Monte Carlo simulations in diffusive media. In DDMC, particles take discrete steps between spatial cells according to a discretized diffusion equation. Thus, DDMC produces accurate solutions while increasing the efficiency of the Monte Carlo calculation. In this paper, we extend previously developed DDMC techniques in several ways that improve the accuracy and utility of DDMC for grey Implicit Monte Carlo calculations. First, we employ a diffusion equation that is discretized in space but is continuous time. Not only is this methodology theoretically more accurate than temporally discretized DDMC techniques, but it also has the benefit that a particle's time is always known. Thus, there is no ambiguity regarding what time to assign a particle that leaves an optically thick region (where DDMC is used) and begins transporting by standard Monte Carlo in an optically thin region. In addition, we treat particles incident on an optically thick region using the asymptotic diffusion-limit boundary condition. This interface technique can produce accurate solutions even if the incident particles are distributed anisotropically in angle. Finally, we develop a method for estimating radiation momentum deposition during the DDMC simulation. With a set of numerical examples, we demonstrate the accuracy and efficiency of our improved DDMC method.
Monte Carlo methods Sequential Monte Carlo
Doucet, Arnaud
Monte Carlo methods Sequential Monte Carlo A. Doucet Carcans Sept. 2011 A. Doucet (MLSS Sept. 2011) Sequential Monte Carlo Sept. 2011 1 / 85 #12;Generic Problem Consider a sequence of probability distributions, Fn = Fn 1 F. A. Doucet (MLSS Sept. 2011) Sequential Monte Carlo Sept. 2011 2 / 85 #12;Generic Problem
Hybrid Pixel-Based Method for Cardiac Ultrasound Fusion Based on Integration of PCA and DWT
Sulaiman, Puteri Suhaiza; Wirza, Rahmita; Dimon, Mohd Zamrin; Khalid, Fatimah; Moosavi Tayebi, Rohollah
2015-01-01
Medical image fusion is the procedure of combining several images from one or multiple imaging modalities. In spite of numerous attempts in direction of automation ventricle segmentation and tracking in echocardiography, due to low quality images with missing anatomical details or speckle noises and restricted field of view, this problem is a challenging task. This paper presents a fusion method which particularly intends to increase the segment-ability of echocardiography features such as endocardial and improving the image contrast. In addition, it tries to expand the field of view, decreasing impact of noise and artifacts and enhancing the signal to noise ratio of the echo images. The proposed algorithm weights the image information regarding an integration feature between all the overlapping images, by using a combination of principal component analysis and discrete wavelet transform. For evaluation, a comparison has been done between results of some well-known techniques and the proposed method. Also, different metrics are implemented to evaluate the performance of proposed algorithm. It has been concluded that the presented pixel-based method based on the integration of PCA and DWT has the best result for the segment-ability of cardiac ultrasound images and better performance in all metrics.
Onar, Omer C [ORNL] [ORNL
2011-01-01
This study presents a bi-directional multi-level power electronic interface for the grid interactions of plug-in hybrid electric vehicles (PHEVs) as well as a novel bi-directional power electronic converter for the combined operation of battery/ultracapacitor hybrid energy storage systems (ESS). The grid interface converter enables beneficial vehicle-to-grid (V2G) interactions in a high power quality and grid friendly manner; i.e, the grid interface converter ensures that all power delivered to/from grid has unity power factor and almost zero current harmonics. The power electronic converter that provides the combined operation of battery/ultra-capacitor system reduces the size and cost of the conventional ESS hybridization topologies while reducing the stress on the battery, prolonging the battery lifetime, and increasing the overall vehicle performance and efficiency. The combination of hybrid ESS is provided through an integrated magnetic structure that reduces the size and cost of the inductors of the ESS converters. Simulation and experimental results are included as prove of the concept presenting the different operation modes of the proposed converters.
Propulsion Airframe Aeroacoustic Integration Effects for a Hybrid Wing Body Aircraft Configuration
NASA Technical Reports Server (NTRS)
Czech, Michael J.; Thomas, Russell H.; Elkoby, Ronen
2010-01-01
An extensive experimental investigation was performed to study the propulsion airframe aeroacoustic effects of a high bypass ratio engine for a hybrid wing body aircraft configuration where the engine is installed above the wing. The objective was to provide an understanding of the jet noise shielding effectiveness as a function of engine gas condition and location as well as nozzle configuration. A 4.7% scale nozzle of a bypass ratio seven engine was run at characteristic cycle points under static and forward flight conditions. The effect of the pylon and its orientation on jet noise was also studied as a function of bypass ratio and cycle condition. The addition of a pylon yielded significant spectral changes lowering jet noise by up to 4dB at high polar angles and increasing it by 2 to 3dB at forward angles. In order to assess jet noise shielding, a planform representation of the airframe model, also at 4.7% scale was traversed relative to the jet nozzle from downstream to several diameters upstream of the wing trailing edge. Installations at two fan diameters upstream of the wing trailing edge provided only limited shielding in the forward arc at high frequencies for both the axisymmetric and a conventional round nozzle with pylon. This was consistent with phased array measurements suggesting that the high frequency sources are predominantly located near the nozzle exit and, consequently, are amenable to shielding. The mid to low frequencies sources were observed further downstream and shielding was insignificant. Chevrons were designed and used to impact the distribution of sources with the more aggressive design showing a significant upstream migration of the sources in the mid frequency range. Furthermore, the chevrons reduced the low frequency source levels and the typical high frequency increase due to the application of chevron nozzles was successfully shielded. The pylon was further modified with a technology that injects air through the shelf of the pylon which was effective in reducing low frequency noise and moving jet noise sources closer to the nozzle exit. In general, shielding effectiveness varied as a function of cycle condition with the cutback condition producing higher shielding compared to sideline power. The configuration with a more strongly immersed chevron and a pylon oriented opposite to the microphones produced the largest reduction in jet noise. In addition to the jet noise source, the shielding of a broadband point noise source was documented with up to 20 dB of noise reduction at directivity angles directly under the shielding surface.
LU,YUNFENG; FAN,HONGYOU; DOKE,NILESH; LOY,DOUGLAS A.; ASSINK,ROGER A.; LAVAN,DAVID A.; BRINKER,C. JEFFREY
2000-06-12
Since the discovery of surfactant-templated silica mesophases, the development of organic modification schemes to impart functionality to the pore surfaces has received much attention. Most recently, using the general class of compounds referred to as bridged silsesquioxanes (RO){sub 3}Si-R{prime}-Si(OR){sub 3} (Scheme 1), three research groups have reported the formation of a new class of poly(bridgedsilsesquioxane) mesophases BSQMs with integral organic functionality. In contrast to previous hybrid mesophases where organic ligands or molecules are situated on pore surfaces, this class of materials necessarily incorporates the organic constituents into the framework as molecularly dispersed bridging ligands. Although it is anticipated that this new mesostructural organization should result in synergistic properties derived from the molecular scale mixing of the inorganic and organic components, few properties of BSQMs have been measured. In addition samples prepared to date have been in the form of granular precipitates, precluding their use in applications like membranes, fluidics, and low k dielectric films needed for all foreseeable future generations of microelectronics.
NASA Astrophysics Data System (ADS)
Zhang, Xingyu; Hosseini, Amir; Subbaraman, Harish; Luo, Jingdong; Jen, Alex K.-Y.; Chung, Chi-jui; Yan, Hai; Pan, Zeyu; Nelson, Robert L.; Chen, Ray T.
2015-03-01
Silicon-organic hybrid integrated devices have emerging applications ranging from high-speed optical interconnects to photonic electromagnetic-field sensors. Silicon slot photonic crystal waveguides (PCWs) filled with electro-optic (EO) polymers combine the slow-light effect in PCWs with the high polarizability of EO polymers, which promises the realization of high-performance optical modulators. In this paper, a broadband, power-efficient, low-dispersion, and compact optical modulator based on an EO polymer filled silicon slot PCW is presented. A small voltage-length product of V?×L=0.282V×mm is achieved, corresponding to an unprecedented record-high effective in-device EO coefficient (r33) of 1230pm/V. Assisted by a backside gate voltage, the modulation response up to 50GHz is observed, with a 3-dB bandwidth of 15GHz, and the estimated energy consumption is 94.4fJ/bit at 10Gbit/s. Furthermore, lattice-shifted PCWs are utilized to enhance the optical bandwidth by a factor of ~10X over other modulators based on non-band-engineered PCWs and ring-resonators.
NASA Astrophysics Data System (ADS)
Darne, Chinmay D.; Lu, Yujie; Tan, I.-Chih; Zhu, Banghe; Rasmussen, John C.; Smith, Anne M.; Yan, Shikui; Sevick-Muraca, Eva M.
2012-12-01
The work presented herein describes the system design and performance evaluation of a miniaturized near-infrared fluorescence (NIRF) frequency-domain photon migration (FDPM) system with non-contact excitation and homodyne detection capability for small animal fluorescence tomography. The FDPM system was developed specifically for incorporation into a Siemens micro positron emission tomography/computed tomography (microPET/CT) commercial scanner for hybrid small animal imaging, but could be adapted to other systems. Operating at 100 MHz, the system noise was minimized and the associated amplitude and phase errors were characterized to be ±0.7% and ±0.3°, respectively. To demonstrate the tomographic ability, a commercial mouse-shaped phantom with 50 µM IRDye800CW and 68Ga containing inclusion was used to associate PET and NIRF tomography. Three-dimensional mesh generation and anatomical referencing was accomplished through CT. A third-order simplified spherical harmonics approximation (SP3) algorithm, for efficient prediction of light propagation in small animals, was tailored to incorporate the FDPM approach. Finally, the PET-NIRF target co-localization accuracy was analyzed in vivo with a dual-labeled imaging agent targeting orthotopic growth of human prostate cancer. The obtained results validate the integration of time-dependent fluorescence tomography system within a commercial microPET/CT scanner for multimodality small animal imaging.
Darne, Chinmay D.; Lu, Yujie; Tan, I-Chih; Zhu, Banghe; Rasmussen, John C.; Smith, Anne M.; Yan, Shikui; Sevick-Muraca, Eva M
2012-01-01
The work presented herein describes system design and performance evaluation of a miniaturized near-infrared fluorescence (NIRF) frequency-domain photon migration (FDPM) system with non-contact excitation and homodyne detection capability for small animal fluorescence tomography. The FDPM system was developed specifically for incorporation into a Siemens microPET/CT commercial scanner for hybrid small animal imaging, but could be adapted to other systems. Operating at 100 MHz, the system noise was minimized and the associated amplitude and phase errors were characterized to be ±0.7% and ±0.3°, respectively. To demonstrate the tomographic ability, a commercial mouse-shaped phantom with 50 ?M IRDye800CW and 68Ga containing inclusion was used to associate PET and NIRF tomography. 3-D mesh generation and anatomical referencing was accomplished through CT. A simplified spherical harmonics approximation (SP3) algorithm, for efficient prediction of light propagation in small animals, was tailored to incorporate FDPM approach. Finally, PET-NIRF target co-localization accuracy was analyzed in vivo with a dual-labeled imaging agent targeting orthotopic growth of human prostate cancer. The results obtained validate the integration of time-dependent fluorescence tomography system within a commercial microPET/CT scanner for multimodality small animal imaging. PMID:23171509
Darne, Chinmay D; Lu, Yujie; Tan, I-Chih; Zhu, Banghe; Rasmussen, John C; Smith, Anne M; Yan, Shikui; Sevick-Muraca, Eva M
2012-12-21
The work presented herein describes the system design and performance evaluation of a miniaturized near-infrared fluorescence (NIRF) frequency-domain photon migration (FDPM) system with non-contact excitation and homodyne detection capability for small animal fluorescence tomography. The FDPM system was developed specifically for incorporation into a Siemens micro positron emission tomography/computed tomography (microPET/CT) commercial scanner for hybrid small animal imaging, but could be adapted to other systems. Operating at 100 MHz, the system noise was minimized and the associated amplitude and phase errors were characterized to be ±0.7% and ±0.3°, respectively. To demonstrate the tomographic ability, a commercial mouse-shaped phantom with 50 µM IRDye800CW and ??Ga containing inclusion was used to associate PET and NIRF tomography. Three-dimensional mesh generation and anatomical referencing was accomplished through CT. A third-order simplified spherical harmonics approximation (SP?) algorithm, for efficient prediction of light propagation in small animals, was tailored to incorporate the FDPM approach. Finally, the PET-NIRF target co-localization accuracy was analyzed in vivo with a dual-labeled imaging agent targeting orthotopic growth of human prostate cancer. The obtained results validate the integration of time-dependent fluorescence tomography system within a commercial microPET/CT scanner for multimodality small animal imaging. PMID:23171509
NASA Astrophysics Data System (ADS)
Sandner, Thilo; Baulig, Claudia; Grasshoff, Thomas; Wildenhain, Michael; Schwarzenberg, Markus; Dahlmann, Hans-Georg; Schwarzer, Stefan
2015-03-01
This paper presents a large aperture micro scanning mirror (MSM) array especially developed for the novel 3D-laser camera Fovea3D. This 3D-camera uses a pulsed ToF technique with 1MVoxel distance measuring rate and targets for a large measurement range of 30…100m and FOV of 120°x60° at video like frame rates. To guarantee a large reception aperture of ? 20mm, large FOV and 3200 Hz bi-directional scanning frequency at the same time, a hybrid assembled MSM array was developed consisting of 22 reception mirrors and a separate sending mirror. A hybrid assembly of frequency selected scanner elements and a driving in parametric resonance were chosen to enable a fully synchronized operation of all scanner elements. For position feedback piezo-resistive position sensors are integrated on each MEMS chip. The paper discusses details of the MEMS system integration including the synchronized operation of multiple scanning elements.
Yan, Sheng; Zhang, Jun; Yuan, Yuan; Lovrecz, George; Alici, Gursel; Du, Haiping; Zhu, Yonggang; Li, Weihua
2015-01-01
This work explores dielectrophoresis (DEP)-active hydrophoresis in sorting particles and cells. The device consists of prefocusing region and sorting region with great potential to be integrated into advanced lab-on-a-chip bioanalysis devices. Particles or cells can be focused in the prefocusing region and then sorted in the sorting region. The DEP-active hydrophoretic sorting is not only based on size but also on dielectric properties of the particles or cells of interest without any labelling. A mixture of 3 and 10 ?m particles were sorted and collected from corresponding outlets with high separation efficiency. According to the different dielectric properties of viable and nonviable Chinese Hamster Ovary (CHO) cells at the medium conductivity of 0.03 S/m, the viable CHO cells were focused well and sorted from cell sample with a high purity. PMID:25363719
Hiroshi Uemura; Hiroshi Hamasaki; Hideto Furuyama; Hideo Numata; Chiaki Takubo; Hideki Shibata
2009-01-01
In order to meet increasing demand for higher-speed signal transmission and smaller electromagnetic noise, we propose the hybrid optical interconnection module with built-in electrical power lines as highly practical optoelectronic interconnection in mobile phones. Highly-flexible integrally-formed OE-FPC with high productivity and reliability was utilized in this module. Optical semiconductor devices and ICs driving such optical devices were all mounted on
Chan-Chiao Lin; Zoran Filipi; Yongsheng Wang; Loucas Louca; Huei Peng; Dennis Assanis; Jeffrey Stein
2001-01-01
A hybrid electric vehicle simulation tool (HE-VESIM) has been developed at the Automotive Research Center of the University of Michigan to study the fuel economy potential of hybrid military\\/civilian trucks. In this paper, the fundamental architecture of the feed-forward parallel hybrid-electric vehicle system is described, together with dynamic equations and basic features of sub-system modules. Two vehicle-level power management control
Lahdenperä, Susanne; Spangar, Anni; Lempainen, Anna-Maija; Joki, Laura; Soukka, Tero
2015-06-21
Switchable lanthanide luminescence is a binary probe technology that inherently enables a high signal modulation in separation-free detection of DNA targets. A luminescent lanthanide complex is formed only when the two probes hybridize adjacently to their target DNA. We have now further adapted this technology for the first time in the integration of a 2-plex polymerase chain reaction (PCR) amplification and hybridization-based solid-phase detection of the amplification products of the Staphylococcus aureus gyrB gene and an internal amplification control (IAC). The assay was performed in a sealed polypropylene PCR chip containing a flat-bottom reaction chamber with two immobilized capture probe spots. The surface of the reaction chamber was functionalized with NHS-PEG-azide and alkyne-modified capture probes for each amplicon, labeled with a light harvesting antenna ligand, and covalently attached as spots to the azide-modified reaction chamber using a copper(i)-catalyzed azide-alkyne cycloaddition. Asymmetric duplex-PCR was then performed with no template, one template or both templates present and with a europium ion carrier chelate labeled probe for each amplicon in the reaction. After amplification europium fluorescence was measured by scanning the reaction chamber as a 10 × 10 raster with 0.6 mm resolution in time-resolved mode. With this assay we were able to co-amplify and detect the amplification products of the gyrB target from 100, 1000 and 10?000 copies of isolated S. aureus DNA together with the amplification products from the initial 5000 copies of the synthetic IAC template in the same sealed reaction chamber. The addition of 10?000 copies of isolated non-target Escherichia coli DNA in the same reaction with 5000 copies of the synthetic IAC template did not interfere with the amplification or detection of the IAC. The dynamic range of the assay for the synthetic S. aureus gyrB target was three orders of magnitude and the limit of detection of 8 pM was obtained. This proof-of-concept study shows that the switchable lanthanide luminescent probes enable separation-free array-based multiplexed detection of the amplification products in a closed-tube PCR which can enable a higher degree of multiplexing than is currently feasible by using different spectrally separated fluorescent probes. PMID:25882638
NASA Astrophysics Data System (ADS)
Joosten, A.; Bochud, F.; Moeckli, R.
2014-08-01
The comparison of radiotherapy techniques regarding secondary cancer risk has yielded contradictory results possibly stemming from the many different approaches used to estimate risk. The purpose of this study was to make a comprehensive evaluation of different available risk models applied to detailed whole-body dose distributions computed by Monte Carlo for various breast radiotherapy techniques including conventional open tangents, 3D conformal wedged tangents and hybrid intensity modulated radiation therapy (IMRT). First, organ-specific linear risk models developed by the International Commission on Radiological Protection (ICRP) and the Biological Effects of Ionizing Radiation (BEIR) VII committee were applied to mean doses for remote organs only and all solid organs. Then, different general non-linear risk models were applied to the whole body dose distribution. Finally, organ-specific non-linear risk models for the lung and breast were used to assess the secondary cancer risk for these two specific organs. A total of 32 different calculated absolute risks resulted in a broad range of values (between 0.1% and 48.5%) underlying the large uncertainties in absolute risk calculation. The ratio of risk between two techniques has often been proposed as a more robust assessment of risk than the absolute risk. We found that the ratio of risk between two techniques could also vary substantially considering the different approaches to risk estimation. Sometimes the ratio of risk between two techniques would range between values smaller and larger than one, which then translates into inconsistent results on the potential higher risk of one technique compared to another. We found however that the hybrid IMRT technique resulted in a systematic reduction of risk compared to the other techniques investigated even though the magnitude of this reduction varied substantially with the different approaches investigated. Based on the epidemiological data available, a reasonable approach to risk estimation would be to use organ-specific non-linear risk models applied to the dose distributions of organs within or near the treatment fields (lungs and contralateral breast in the case of breast radiotherapy) as the majority of radiation-induced secondary cancers are found in the beam-bordering regions.
Monte Carlo results for the hydrogen Hugoniot
V. Bezkrovniy; V. S. Filinov; D. Kremp; M. Bonitz; M. Schlanges; W. D. Kraeft; P. R. Levashov; V. E. Fortov
2004-01-01
We propose a theoretical Hugoniot relation obtained by combining results for the equation of state from the direct path integral Monte Carlo technique (DPIMC) and those from reaction ensemble Monte Carlo (REMC) simulations. The main idea of this proposal is based on the fact that the DPMIC technique provides first-principle results for a wide range of densities and temperatures including
Perkins, James Michael, 1978-
2007-01-01
A new heterogeneous integration technique has been developed and demonstrated to integrate vertical cavity surface emitting lasers (VCSELs) on silicon CMOS integrated circuits for optical interconnect applications. Individual ...
Bayesian Monte Carlo Carl Edward Rasmussen and Zoubin Ghahramani
Ghahramani, Zoubin
Bayesian Monte Carlo Carl Edward Rasmussen and Zoubin Ghahramani Gatsby Computational Neuroscience,zoubin@gatsby.ucl.ac.uk http://www.gatsby.ucl.ac.uk Abstract We investigate Bayesian alternatives to classical Monte Carlo methods for evaluating integrals. Bayesian Monte Carlo (BMC) allows the in- corporation of prior knowledge
NASA Astrophysics Data System (ADS)
Ghassib, Humam B.; Sakhel, Asaad R.; Obeidat, Omar; Al-Oqali, Amer; Sakhel, Roger R.
2012-01-01
We demonstrate the effectiveness of a statistical potential (SP) in the description of fermions in a worm-algorithm path-integral Monte Carlo simulation of a few 3He atoms floating on a 4He layer adsorbed on graphite. The SP in this work yields successful results, as manifested by the clusterization of 3He, and by the observation that the 3He atoms float on the surface of 4He. We display the positions of the particles in 3D coordinate space, which reveal clusterization of the 3He component. The correlation functions are also presented, which give further evidence for the clusterization.
NASA Astrophysics Data System (ADS)
Zagórski, R.; Voitsekhovitch, I.; Ivanova-Stanik, I.; Köchl, F.; Belo, P.; Fable, E.; Garcia, J.; Garzotti, L.; Hobirk, J.; Hogeweij, G. M. D.; Joffrin, E.; Litaudon, X.; Polevoi, A. R.; Telesca, G.; contributors, JET
2015-05-01
The compatibility of two operational constraints—operation above the L–H power threshold and at low power to divertor—is examined for ITER long pulse H-mode and hybrid scenarios in integrated core–scrape off layer (SOL)–divertor modelling including impurities (intrinsic Be, He, W and seeded Ne). The core thermal, particle and momentum transport is simulated with the GLF23 transport model tested in the self-consistent simulations of temperatures, density and toroidal rotation velocity in JET hybrid discharges and extrapolated to ITER. The beneficial effect of toroidal rotation velocity on fusion gain is shown. The sensitivity studies with respect to operational (separatrix and pedestal density, Ne gas puff) and unknown physics (W convective velocity and perpendicular diffusion in SOL as well as W prompt re-deposition) parameters are performed to determine their influence on the operational window and fusion gain.
W. M. Mattheij; R. Eijlander; J. R. A. Koning; K. M. Louwes
1992-01-01
Somatic fusions between the cultivated potato Solanum tuberosum and the wild species S. circaeifolium subsp. circaeifolium Bitter were produced in order to incorporate desirable traits into the potato gene pool. Selection of the putative hybrids was based on a difference in callus morphology between the hybrids and their parents, with the hybrids showing typical purple-colored cells in otherwise green calli.
S. D. G. Jayasinghe; D. M. Vilathgamuwa; U. K. Madawala
2011-01-01
Battery-supercapacitor hybrid energy storage systems are becoming popular in the renewable energy sector due to their improved power and energy performances. These hybrid systems require separate dc-dc converters, or at least one dc-dc converter for the supercapacitor bank, to connect them to the dc-link of the grid interfacing inverter. These additional dc-dc converters increase power losses, complexity and cost. Therefore,
NASA Astrophysics Data System (ADS)
Alexoudi, T.; Fitsios, D.; Kanellos, G. T.; Pleros, N.; Tekin, T.; Cherchi, M.; Ylinen, S.; Harjanne, M.; Kapulainen, M.; Aalto, T.
2014-03-01
Hybrid integration on Silicon-on-Insulator (SOI) has emerged as a practical solution for compact and high-performance Photonic Integrated Circuits (PICs). It aims at combining the cost-effectiveness and CMOS-compatibility benefits of the low-loss SOI waveguide platform with the versatile active optical functions that can be realized by III-V photonic materials. The utilization of SOI, as an integration board, with ?m-scale dimensions allows for an excellent optical mode matching between silicon rib waveguides and active chips, allowing for minimal-loss coupling of the pre-fabricated IIIV components. While dual-facet coupling as well as III-V multi-element array bonding should be employed to enable enhanced active on-chip functions, so far only single side SOA bonding has been reported. In the present communication, we present a novel integration scheme that flip-chip bonds a 6-SOA array on 4-?m thick SOI technology by coupling both lateral SOA facets to the waveguides, and report on the experimental results of wavelength conversion operation of a dual-element Semiconductor Optical Amplifier - Mach Zehnder Interferometer (SOA-MZI) circuit. Thermocompression bonding was applied to integrate the pre-fabricated SOAs on SOI, with vertical and horizontal alignment performed successfully at both SOA facets. The demonstrated device has a footprint of 8.2mm x 0.3mm and experimental evaluation revealed a 12Gb/s wavelength conversion operation capability with only 0.8dB power penalty for the first SOA-MZI-on-SOI circuit and a 10Gb/s wavelength conversion operation capability with 2 dB power penalty for the second SOA-MZI circuit. Our experiments show how dual facet integration can significantly increase the level of optical functionalities achievable by flip-chip hybrid technology and pave the way for more advanced and more densely PICs.
NASA Astrophysics Data System (ADS)
Manipon, G. J. M.; Hua, H.; Owen, S. E.; Sacco, G. F.; Agram, P. S.; Moore, A. W.; Yun, S. H.; Fielding, E. J.; Lundgren, P.; Rosen, P. A.; Webb, F.; Liu, Z.; Smith, A. T.; Wilson, B. D.; Simons, M.; Poland, M. P.; Cervelli, P. F.
2014-12-01
The Hybrid Science Data System (HySDS) scalably powers the ingestion, metadata extraction, cataloging, high-volume data processing, and publication of the geodetic data products for the Advanced Rapid Imaging & Analysis for Monitoring Hazard (ARIA-MH) project at JPL. HySDS uses a heterogeneous set of worker nodes from private & public clouds as well as virtual & bare-metal machines to perform every aspect of the traditional science data system. For our science data users, the forefront of HySDS is the facet search interface, FacetView, which allows them to browse, filter, and access the published products. Users are able to explore the collection of product metadata information and apply multiple filters to constrain the result set down to their particular interests. It allows them to download these faceted products for further analysis and generation of derived products. However, we have also employed a novel approach to faceting where it is also used to apply constraints for custom monitoring of products, system resources, and triggers for automated data processing. The power of the facet search interface is well documented across various domains and its usefulness is rooted in the current state of existence of metadata. However, user needs usually extend beyond what is currently present in the data system. A user interested in synthetic aperture radar (SAR) data over Kilauea will download them from FacetView but would also want email notification of future incoming scenes. The user may even want that data pushed to a remote workstation for automated processing. Better still, these future products could trigger HySDS to run the user's analysis on its array of worker nodes, on behalf of the user, and ingest the resulting derived products. We will present our findings in integrating an ancillary, user-defined, system-driven processing system for HySDS that allows users to define faceted rules based on facet constraints and triggers actions when new SAR data products arrive that match the constraints. We will discuss use cases where users have defined rules for the automated generation of InSAR derived products: interferograms for California and Kilauea, time-series analyses, and damage proxy maps. These findings are relevant for science data system development of the proposed NASA-ISRO SAR mission.
Yukito Iba
2001-01-01
``Extended Ensemble Monte Carlo'' is a generic term that indicates a set of algorithms, which are now popular in a variety of fields in physics and statistical information processing. Exchange Monte Carlo (Metropolis-Coupled Chain, Parallel Tempering), Simulated Tempering (Expanded Ensemble Monte Carlo) and Multicanonical Monte Carlo (Adaptive Umbrella Sampling) are typical members of this family. Here, we give a cross-disciplinary
McCreddin, A; Alam, M S; McNabola, A
2015-01-01
An experimental assessment of personal exposure to PM10 in 59 office workers was carried out in Dublin, Ireland. 255 samples of 24-h personal exposure were collected in real time over a 28 month period. A series of modelling techniques were subsequently assessed for their ability to predict 24-h personal exposure to PM10. Artificial neural network modelling, Monte Carlo simulation and time-activity based models were developed and compared. The results of the investigation showed that using the Monte Carlo technique to randomly select concentrations from statistical distributions of exposure concentrations in typical microenvironments encountered by office workers produced the most accurate results, based on 3 statistical measures of model performance. The Monte Carlo simulation technique was also shown to have the greatest potential utility over the other techniques, in terms of predicting personal exposure without the need for further monitoring data. Over the 28 month period only a very weak correlation was found between background air quality and personal exposure measurements, highlighting the need for accurate models of personal exposure in epidemiological studies. PMID:25260856
Alwee, Razana; Shamsuddin, Siti Mariyam Hj; Sallehuddin, Roselina
2013-01-01
Crimes forecasting is an important area in the field of criminology. Linear models, such as regression and econometric models, are commonly applied in crime forecasting. However, in real crimes data, it is common that the data consists of both linear and nonlinear components. A single model may not be sufficient to identify all the characteristics of the data. The purpose of this study is to introduce a hybrid model that combines support vector regression (SVR) and autoregressive integrated moving average (ARIMA) to be applied in crime rates forecasting. SVR is very robust with small training data and high-dimensional problem. Meanwhile, ARIMA has the ability to model several types of time series. However, the accuracy of the SVR model depends on values of its parameters, while ARIMA is not robust to be applied to small data sets. Therefore, to overcome this problem, particle swarm optimization is used to estimate the parameters of the SVR and ARIMA models. The proposed hybrid model is used to forecast the property crime rates of the United State based on economic indicators. The experimental results show that the proposed hybrid model is able to produce more accurate forecasting results as compared to the individual models. PMID:23766729
Wu, Weitai; Shen, Jing; Banerjee, Probal; Zhou, Shuiqin
2010-10-01
We report a class of core-shell structured hybrid nanogels to demonstrate the conception of integrating the functional building blocks into a single nanoparticle system for simultaneously optical temperature-sensing, cancer cell targeting, fluorescence imaging, and combined chemo-photothermal treatment. The hybrid nanogels were constructed by coating the Ag-Au bimetallic NP core with a thermo-responsive nonlinear poly(ethylene glycol) (PEG)-based hydrogel as shell, and semi-interpenetrating the targeting ligands of hyaluronic acid chains into the surface networks of gel shell. The Ag-Au NP core can emit strong visible fluorescence for imaging of mouse melanoma B16F10 cells. The reversible thermo-responsive volume phase transition of the nonlinear PEG-based gel shell cannot only modify the physicochemical environment of the Ag-Au NP core to manipulate the fluorescence intensity for sensing the environmental temperature change, but also provide a high loading capacity for a model anticancer drug temozolomide and offer a thermo-triggered drug release. The drug release can be induced by both the heat generated by external NIR irradiation and the temperature increase of local environmental media. The ability of the hybrid nanogels to combine the local specific chemotherapy with external NIR photothermal treatment significantly improves the therapeutic efficacy due to a synergistic effect. PMID:20643481
Cinget, Benjamin; de Lafontaine, Guillaume; Gérardi, Sébastien; Bousquet, Jean
2015-06-01
Secondary contact between closely related taxa routinely occurs during postglacial migrations. After initial contact, the location of hybrid zones may shift geographically or remain spatially stable over time in response to various selective pressures or neutral processes. Studying the extent and direction of introgression using markers having contrasted levels of gene flow can help unravel the historical dynamics of hybrid zones. Thanks to their contrasted maternal and paternal inheritance, resulting in different levels of gene flow for mitochondrial and chloroplast DNA (mtDNA and cpDNA), the Pinaceae stand out as a relevant biological model for this purpose. The objective of the study was to assess whether the hybrid zone between Abies balsamea and Abies lasiocarpa (two largely distributed Pinaceae) has moved or remained stable over time by analysing the distribution of cytoplasmic DNA variation as well as published palaeobotanical data. Interspecific gene flow was higher for cpDNA than mtDNA markers; hence, the geographic distribution of mitotypes was more congruent with species distributions than chlorotypes. This genetic signature was contrary to expectations under a moving hybrid zone scenario, as well as empirical observations in other conifers. Genetic evidence for this rare instance of stable hybrid zone was corroborated by the colonization chronology derived from published fossil data, indicating that the two fir species initially came into contact in the area corresponding to the current sympatric zone 11 kyr ago. While an explanatory analysis suggested the putative influence of various environmental factors on the relative abundance of cytoplasmic genome combinations, further research appears necessary to assess the role of both demographic history and selective factors in driving the dynamics of hybrid zones. PMID:25865063
Monte Carlo EM for Generalized Linear Mixed Models using Randomized Spherical Radial
Booth, James
Monte Carlo EM for Generalized Linear Mixed Models using Randomized Spherical Radial Integration by Monte Carlo methods. However, in practice, the Monte Carlo sample sizes required for convergence for such methods. One solution is to use Monte Carlo approximation, as proposed by Wei and Tanner (1990
Shuai Lu; Keith A. Corzine; Mehdi Ferdowsi
2007-01-01
This paper proposes a new energy storage system (ESS) design, including both batteries and ultracapacitors (UCs) in hybrid electric vehicle (HEV) and electric vehicle applications. The conventional designs require a DC-DC converter to interface the UC unit. Herein, the UC can be directly switched across the motor drive DC link during the peak power demands. The resulting wide voltage variation
A. D. Adams; Greg A. Johnson; Noel D. Jolivet; Jeff L. Metschuleit
1992-01-01
When testing infrared readouts, detector-readout hybrid assemblies, or focal plane arrays (FPAs), performance optimization is usually limited to adjustment of biases or clock rails, or subtle changes in readout timing. These generally result in global changes to the characteristics of the entire array rather than affecting individual pixels and channels. Using a scanning system that incorporates per channel gain normalization
F. Tavares; R. Johri; A. Salvi; S. Baseley; Z. S. Filipi
2011-01-01
The energy supply, environmental concerns, and upcoming regulation\\u000d\\u000a\\u0009for heavy trucks provide a strong impetus for development of new\\u000d\\u000a\\u0009clean and efficient vehicle propulsion technologies. Hybrid powertrains\\u000d\\u000a\\u0009provide significant opportunities for reducing fuel consumption and\\u000d\\u000a\\u0009exhaust emission. The research aimed at novel hybrid configurations\\u000d\\u000a\\u0009typically starts with a simulation analysis and optimization for\\u000d\\u000a\\u0009best fuel economy, but assessment of emissions
2005-01-01
This report summarizes the results of a research and development (R&D) program to design and optimize an active desiccant-vapor compression hybrid rooftop system. The primary objective was to combine the strengths of both technologies to produce a compact, high-performing, energy-efficient system that could accommodate any percentage of outdoor air and deliver essentially any required combination of temperature and humidity, or
M. Mahmoud; A. Tawfik; F. Samhan; F. El-Gohary
2009-01-01
This paper presents an evaluation of a combined wastewater treatment train consisting of an anaerobic hybrid reactor (AHR) followed by a downflow hanging sponge (DHS) system. The combined system was operated at a total constant hydraulic retention time (HRT) of 8 h (AHR: 6.0 h and DHS: 2.0 h) and an average organic loading rate of 1.9 kg COD\\/m.d for
Polynomial Stochastic Hybrid Systems Jo~ao Pedro Hespanha
Hespanha, João Pedro
Polynomial Stochastic Hybrid Systems Jo~ao Pedro Hespanha Center for Control Engineering stochastic hybrid systems (pSHSs), which generally correspond to stochastic hybrid systems with polynomial the accuracy of the results obtained through comparisons with Monte Carlo simulations. These examples include
Topological Zero Modes in Monte Carlo Simulations
Dilger, H
2015-01-01
We present an improvement of global Metropolis updating steps, the instanton hits, used in a hybrid Monte Carlo simulation of the two-flavor Schwinger model with staggered fermions. These hits are designed to change the topological sector of the gauge field. In order to match these hits to an unquenched simulation with pseudofermions, the approximate zero mode structure of the lattice Dirac operator has to be considered explicitly.
Buckle, Tessa; Kuil, Joeri; van den Berg, Nynke S.; Bunschoten, Anton; Lamb, Hildo J.; Yuan, Hushan; Josephson, Lee; Jonkers, Jos; Borowsky, Alexander D.; van Leeuwen, Fijs W. B.
2013-01-01
Screening of biomarker expression levels in tumor biopsy samples not only provides an assessment of prognostic and predictive factors, but may also be used for selection of biomarker-specific imaging strategies. To assess the feasibility of using a biopsy specimen for a personalized selection of an imaging agent, the chemokine receptor 4 (CXCR4) was used as a reference biomarker. Methods A hybrid CXCR4 targeting peptide (MSAP-Ac-TZ14011) containing a fluorescent dye and a chelate for radioactive labeling was used to directly compare initial flow cytometry–based target validation in fresh tumor tissue to in vivo single photon emission computed tomography (SPECT) imaging and in vivo and ex vivo fluorescence imaging. Results Flow cytometric analysis of mouse tumor derived cell suspensions enabled discrimination between 4T1 control tumor lesions (with low levels of CXCR4 expression) and CXCR4 positive early, intermediate and late stage MIN-O lesions based on their CXCR4 expression levels; CXCR4basal, CXCR4+ and CXCR4++ cell populations could be accurately discriminated. Mean fluorescent intensity ratios between expression in MIN-O and 4T1 tissue found with flow cytometry were comparable to ratios obtained with in vivo SPECT/CT and fluorescence imaging, ex vivo fluorescence evaluation and standard immunohistochemistry. Conclusion The hybrid nature of a targeting imaging agent like MSAP-Ac-TZ14011 enables integration of target selection, in vivo imaging and ex vivo validation using a single agent. The use of biopsy tissue for biomarker screening can readily be expanded to other targeting hybrid imaging agents and can possibly help increase the clinical applicability of tumor-specific imaging approaches. PMID:23326303
Jarrell, John D; Dolly, Brandon; Morgan, Jeffrey R
2010-03-01
Metal-organic chemistry allows for molecular mixing and creation of a range of submicron phase-separated structures from normally brittle metal oxides and flexible polymers with improved bioactivity and delivery properties. In this study, we used a high throughput platform to investigate the influence of organic metal oxide doping of polydimethylsiloxane (PDMS) coatings on cellular bioactivity and controlled release of vanadium compared with titanium oxide coatings without additional PDMS. Metal-organic-derived titanium and or vanadium was doped into PDMS and used to form a coating on the bottom of cell culture microplates in the absence of added water, acids, or bases. These hybrid coatings were rapidly screened to establish how titanium and vanadium concentration influences cell proliferation, adhesion, and morphology. We demonstrate that titanium doping of PDMS can be used to improve cell proliferation and adhesion, and that vanadium doping caused a biphasic dose response in proliferation. A 28-day vanadium and titanium elution study indicated that titanium was not released, but the presence of PDMS in coatings increased delivery rates of vanadium compared with titania coatings without polymer. Hybrid coatings of titanium-doped polymers have potential for improving wound healing dynamics, soft-tissue integration of medical implants, and use as controlled delivery vehicles. PMID:19301265
Dong, Haiyan; Wu, Zai-Sheng; Xu, Jianguo; Ma, Ji; Zhang, Huijuan; Wang, Jie; Shen, Weiyu; Xie, Jingjing; Jia, Lee
2015-10-15
Molecular beacon (MB) is widely explored as a signaling probe in powerful biosensing systems, for example, enzyme-assisted strand displacement amplification (SDA)-based system. The existing polymerization-based amplification system is often composed of recognition element, primer, template and fluorescence reporter. To develop a new MB sensing system and simply the signal amplification design, we herein attempted to propose a multifunctional integrated MB (MI-MB) for the polymerization amplification detection of target DNA via introducing a G-rich fragment into the loop of MB without using any exogenous auxiliary oligonucleotide probe. Utilizing only one MI-MB probe, the p53 target gene could trigger the cycles of hybridization/polymerization/displacement, resulting in amplification of the target hybridization event. Thus, the p53 gene can be detected down to 5×10(-10)M with the linear response range from 5×10(-10)M to 4×10(-7)M. Using the MI-MB, we could readily discriminate the point mutation-contained p53 from the wild-type one. As a proof-of-concept study, owing to its simplicity and multifunction, including recognition, replication, amplification and signaling, the MI-MB exhibits the great potential for the development of different biosensors for various biomedical applications, especially, for early cancer diagnosis. PMID:25982726
NASA Astrophysics Data System (ADS)
Skarlatos, A.; Gilles-Pascaud, C.; Pichenot, G.; Cattiaux, G.; Sollier, T.
2010-02-01
A hybrid Volume Integral Method (VIM)—Finite Elements Method (FEM) model for the numerical modeling of eddy current inspection of steam generator (SG) tubes near quadrifoiled tube support plates (TSP) is presented. The coupled approach combines the flexibility of the FEM in modeling complex geometries with the numerical efficiency of the VIM, reducing the computational time demanded for the solution of the problem. Material deposit in the TSP openings, responsible for clogging up effects, can also be taken into account with this approach and will be considered in a next stage. The present work is conducted in the context of the further development of the CIVA nondestructive evaluation simulation platform, notably within the undertaken developments concerning coupled FEM-VIM calculations.
NASA Astrophysics Data System (ADS)
Yagi, Hideki; Inoue, Naoko; Masuyama, Ryuji; Katsuyama, Tomokazu; Kikuchi, Takehiko; Onishi, Yutaka; Yoneda, Yoshihiro; Shoji, Hajime
2014-02-01
The InP-based pin-photodiode array monolithically integrated with a 90° hybrid consisting of multimode interference structures was fabricated using the butt-joint regrowth for compact 100 Gbps coherent receivers. The low dark current of less than 0.2 nA was obtained with InP passivation effect through the selective regrowth process in four-channel photodiodes. A responsivity including total loss of 8.3 dB in the waveguide was as high as 0.14 A/W. The wide 3 dB bandwidth of 24 GHz at a low reverse bias voltage of 1.6 V was also achieved under high optical input power conditions (photocurrent: 4 mA).
Bowers, John
as a means of implementing Light Detection and Ranging (LIDAR) and free-space communication links without complexity. In this work we demonstrate a free-space diode laser together with beam steering implemented on communication, optical phased array, laser, hybrid silicon, integrated optics, beam steering, photonic
Mineralogy of Libya Montes, Mars
NASA Astrophysics Data System (ADS)
Perry, K. A.; Bishop, J. L.; McKeown, N. K.
2009-12-01
Observations by CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) have revealed a range of minerals in Libya Montes including olivine, pyroxene, and phyllosilicate [1]. Here we extend our spectral analyses of CRISM images in Libya Montes to identify carbonates. We have also performed detailed characterization of the spectral signature of the phyllosilicate- and carbonate-bearing outcrops in order to constrain the types of phyllosilicates and carbonates present. Phyllosilicate-bearing rocks in Libya Montes have spectral bands at 1.42, 2.30 and 2.39 µm, consistent with Fe- and Mg- bearing smectites. The mixture of Fe and Mg in Libya Montes may be within the clay mineral structure or within the CRISM pixel. Because the pixels have 18 meter/pixel spatial resolution, it is possible that the bands observed are due to the mixing of nontronite and saponite rather than a smectite with both Fe and Mg. Carbonates found in Libya Montes are similar to those found in Nili Fossae [2]. The carbonates have bands centered at 2.30 and 2.52 µm. Libya Montes carbonates most closely resemble the Mg-carbonate, magnesite. Olivine spectra are seen throughout Libya Montes, characterized by a positive slope from 1.2-1.8 µm. Large outcrops of olivine are relatively rare on Mars [3]. This implies that fresh bedrock has been recently exposed because olivine weathers readily compared to pyroxene and feldspar. Pyroxene in Libya Montes resembles an Fe-bearing orthopyroxene with a broad band centered at 1.82 µm. The lowermost unit identified in Libya Montes is a clay-bearing unit. Overlying this is a carbonate-bearing unit with a clear unit division visible in at least one CRISM image. An olivine-bearing unit unconformably overlies these two units and may represent a drape related to the Isidis impact, as suggested for Nili Fossae [2]. However, it appears that the carbonate in Libya Montes is an integral portion of the rock underlying the olivine-bearing unit rather than an alteration product, contrasting with proposed stratigraphy for Nili Fossae. The uppermost unit identified is a pyroxene-bearing unit. Some spectra of clays and carbonates in this region present a slope from 1.2 to 1.8 µm similar to olivine. Laboratory experiments were conducted in attempt to understand the relationship of mixtures including olivine, nontronite, and magnesite. The characteristic olivine slope is evident in the spectra in any mixture, even with as little as 10% olivine. In ternary mixtures, the magnesite is almost completely overshadowed by the nontronite and olivine characteristics. The discovery of clays and carbonates in Libya Montes indicates that there was an aqueous environment with neutral pH in the past. In addition, water needs to be relatively still and deep for the small particles to precipitate out and form into the minerals. On Earth, this would be a still lake or deep ocean, and perhaps a similar environment may have been present here in Mars’ past. References [1] Bishop, J. L., et al. (2007) 7th Int'l Mars Conf. [2] Ehlmann, B. L., et al. (2008) Science, 322, 1828. [3] Mustard, J. F., et al. (2008) Nature, 454, 07305.
Shell model Monte Carlo methods
Koonin, S.E. [California Inst. of Tech., Pasadena, CA (United States). W.K. Kellogg Radiation Lab.; Dean, D.J. [Oak Ridge National Lab., TN (United States)
1996-10-01
We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, thermal behavior of {gamma}-soft nuclei, and calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. 87 refs.
Discrete diffusion Monte Carlo for frequency-dependent radiative transfer
Densmore, Jeffrey D [Los Alamos National Laboratory; Kelly, Thompson G [Los Alamos National Laboratory; Urbatish, Todd J [Los Alamos National Laboratory
2010-11-17
Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations. In this paper, we develop an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold. Above this threshold we employ standard Monte Carlo. With a frequency-dependent test problem, we confirm the increased efficiency of our new DDMC technique.
Hybrid solar-fossil fuel power generation
Sheu, Elysia J. (Elysia Ja-Zeng)
2012-01-01
In this thesis, a literature review of hybrid solar-fossil fuel power generation is first given with an emphasis on system integration and evaluation. Hybrid systems are defined as those which use solar energy and fuel ...
Brown, F.B.; Sutton, T.M.
1996-02-01
This report is composed of the lecture notes from the first half of a 32-hour graduate-level course on Monte Carlo methods offered at KAPL. These notes, prepared by two of the principle developers of KAPL`s RACER Monte Carlo code, cover the fundamental theory, concepts, and practices for Monte Carlo analysis. In particular, a thorough grounding in the basic fundamentals of Monte Carlo methods is presented, including random number generation, random sampling, the Monte Carlo approach to solving transport problems, computational geometry, collision physics, tallies, and eigenvalue calculations. Furthermore, modern computational algorithms for vector and parallel approaches to Monte Carlo calculations are covered in detail, including fundamental parallel and vector concepts, the event-based algorithm, master/slave schemes, parallel scaling laws, and portability issues.
Kumar, Ramesh; Pal, Parimal
2015-02-01
Experimental investigations were carried out on continuous and direct production of poly-(?-glutamic acid) in a hybrid reactor system that integrated conventional fermentative production step with membrane-based downstream separation and purification. Novelty of the integrated system lies in high degree of purity, conversion, yield and productivity of poly-(?-glutamic acid) through elimination of substrate-product inhibitions of traditional batch production system. This new system is compact, flexible, eco-friendly and largely fouling-free ensuring steady and continuous production of poly-(?-glutamic acid) directly from a renewable carbon source at the rate of 0.91 g/L/h. Cross-flow microfiltration membrane modules ensured almost complete separation and recycle of cells without much fouling problem. Well-screened ultrafiltration membrane module helped to concentrate poly-(?-glutamic acid) while ensuring recovery and recycle of 96% unconverted carbon source resulting in yield of 0.6g/g along with high product purity. PMID:25484125
ERIC Educational Resources Information Center
Reisslein, Jana; Seeling, Patrick; Reisslein, Martin
2005-01-01
An important challenge in the introductory communication networks course in electrical and computer engineering curricula is to integrate emerging topics, such as wireless Internet access and network security, into the already content-intensive course. At the same time it is essential to provide students with experiences in online collaboration,…
Kushner, Mark
for plasma processing reactors Michael J. Grapperhausa) and Mark J. Kushnerb) University of Illinois, 1406 W In high plasma density [e] 1011 1012 cm 3 reactors for materials processing, the sheath thickness been integrated into a two-dimensional model for plasma etching reactors. The basis of the sheath model
Esfandyar Mazhari; Jiayun Zhao; Nurcin Celik; Seungho Lee; Young-Jun Son; Larry Head
2011-01-01
Unlike fossil-fueled generation, solar energy resources are geographically distributed and highly intermittent, which makes their direct control extremely difficult and requires storage units as an additional concern. The goal of this research is to design and develop a flexible tool, which will allow us to obtain (1) an optimal capacity of an integrated photovoltaic (PV) system and storage units and
A. Ganguly; D. Misra; S. Ghosh
2010-01-01
This paper presents the modeling and analysis of a greenhouse-integrated power system consisting of solar photovoltaic panels, electrolyzer bank and Polymer Electrolyte Membrane (PEM) fuel cell stacks. Electric power is generated in an array of solar photovoltaic modules. Excess energy after meeting the requirements of the greenhouse during peak sunshine hours, is supplied to an electrolyzer bank to generate hydrogen
Bowers, John
93106, USA 2 Intel Corporation, 2200 Mission College Blvd, SC12-326, Santa Clara, California 95054, USA University of California, Santa Barbara, Department of Electrical and Computer Engineering, Santa Barbara, CA silicon evanescent racetrack laser with integrated photodetectors has been demonstrated running continuous
Monte Carlo Methods for the Linearized Poisson-Boltzmann Equation
Simonov, Nikolai Aleksandrovich
algo- rithm, another, related, Monte Carlo algorithm is presented. This modified Monte Carlo method- timating certain Gaussian path integrals without the need for simulating Brownian trajectories in detail. We then similarly interpret the exponential weight in the Feynman-Kac formula as a survival
Inverse Monte Carlo: a unified reconstruction algorithm for SPECT
Carey E. Floyd; R. E. Coleman; R. J. Jaszczak
1985-01-01
Inverse Monte Carlo (IMOC) is presented as a unified reconstruction algorithm for Emission Computed Tomography (ECT) providing simultaneous compensation for scatter, attenuation, and the variation of collimator resolution with depth. The technique of inverse Monte Carlo is used to find an inverse solution to the photon transport equation (an integral equation for photon flux from a specified source) for a
NASA Astrophysics Data System (ADS)
Nagarajan, Rao M.; Rask, Steven D.
1988-06-01
A hybrid lithography technique is described in which selected levels are fabricated by high resolution direct write electron beam lithography and all other levels are fabricated optically. This technique permits subhalf micron geometries and the site-by-site alignment for each field written by electron beam lithography while still maintaining the high throughput possible with optical lithography. The goal is to improve throughput and reduce overall cost of fabricating MIMIC GaAS chips without compromising device performance. The lithography equipment used for these experiments is the Cambridge Electron beam vector scan system EBMF 6.4 capable of achieving ultra high current densities with a beam of circular cross section and a gaussian intensity profile operated at 20 kev. The optical aligner is a Karl Suss Contact aligner. The flexibility of the Cambridge electron beam system is matched to the less flexible Karl Suss contact aligner. The lithography related factors, such as image placement, exposure and process related analyses, which influence overlay, pattern quality and performance, are discussed. A process chip containing 3.2768mm fields in an eleven by eleven array was used for alignment evaluation on a 3" semi-insulating GaAS wafer. Each test chip contained five optical verniers and four Prometrix registration marks per field along with metal bumps for alignment marks. The process parameters for these chips are identical to those of HEMT/epi-MESFET ohmic contact and gate layer processes. These layers were used to evaluate the overlay accuracy because of their critical alignment and dimensional control requirements. Two cases were examined: (1) Electron beam written gate layers aligned to optically imaged ohmic contact layers and (2) Electron beam written gate layers aligned to electron beam written ohmic contact layers. The effect of substrate charging by the electron beam is also investigated. The resulting peak overlay error accuracies are: (1) Electron beam to optical with t 0.2?m (2 sigma) and (2) Electron beam to electron beam with f 0.l?m (2 sigma). These results suggest that the electron beam/optical hybrid lithography techniques could be used for MIMIC volume production as alignment tolerances required by GaAS chips are met in both cases. These results are discussed in detail.
Duncavage, Eric J.; Magrini, Vincent; Becker, Nils; Armstrong, Jon R.; Demeter, Ryan T.; Wylie, Todd; Abel, Haley J.; Pfeifer, John D.
2011-01-01
Although next-generation sequencing (NGS) has been the domain of large genome centers, it is quickly becoming more accessible to general pathology laboratories. In addition to finding single-base changes, NGS allows for the detection of larger structural variants, including insertions/deletions, translocations, and viral insertions. We describe the use of targeted NGS on DNA extracted from formalin-fixed, paraffin-embedded (FFPE) tissue, and show that the short read lengths of NGS are ideally suited to fragmented DNA obtained from FFPE tissue. Further, we describe a novel method for performing hybrid-capture target enrichment using PCR-generated capture probes. As a model, we captured the 5.3-kb Merkel cell polyomavirus (MCPyV) genome in FFPE cases of Merkel cell carcinoma using inexpensive, PCR-derived capture probes, and achieved up to 37,000-fold coverage of the MCPyV genome without prior virus-specific PCR amplification. This depth of coverage made it possible to reproducibly detect viral genome deletions and insertion sites anywhere within the human genome. Out of four cases sequenced, we identified the 5? insertion sites in four of four cases and the 3? sites in three of four cases. These findings demonstrate the potential for an inexpensive gene targeting and NGS method that can be easily adapted for use with FFPE tissue to identify large structural rearrangements, opening up the possibility for further discovery from archival tissue. PMID:21497292
NSDL National Science Digital Library
AMPS GK-12 Program,
At its core, the LEGO® MINDSTORMS® NXT product provides a programmable microprocessor. Students use the NXT processor to simulate an experiment involving thousands of uniformly random points placed within a unit square. Using the underlying geometry of the experimental model, as well as the geometric definition of the constant ? (pi), students form an empirical ratio of areas to estimate a numerical value of ?. Although typically used for numerical integration of irregular shapes, in this activity, students use a Monte Carlo simulation to estimate a common but rather complex analytical form—the numerical value of the most famous irrational number, ?.
Yanrui Geng; Richard Deurloo; Luisa Bastos
2011-01-01
Differential carrier phase observations from GPS (Global Positioning System) integrated with high-rate sensor measurements,\\u000a such as those from an inertial navigation system (INS) or an inertial measurement unit (IMU), in a tightly coupled approach\\u000a can guarantee continuous and precise geo-location information by bridging short outages in GPS and providing a solution even\\u000a when less than four satellites are visible. However,
Thomas C. Henderson; Brandt Erickson; Travis Longoria; Edward Grant; Kyle Luthy; Leonardo Mattos; Matt Craver
2005-01-01
Biswas et al. (1) introduced a probabilistic approach to inference with limited information in sensor networks. They represented the sensor network as a Bayesian network and performed approximate inference using Markov Chain Monte Carlo (MCMC). The goal is to robustly answer queries even under noisy or partial information scenarios. We propose an alter- native method based on simple Monte Carlo
Monte Carlo techniques for direct lighting calculations
Peter Shirley; Changyaw Wang; Kurt Zimmerman
1996-01-01
In a distributed ray tracer, the sampling strategy is the crucial part of the direct lighting calculation. Monte Carlo integration with importance sampling is used to carry out this calculation. Importance sampling involves the design of integrand-specific probability density functions that are used to generate sample points for the numerical quadrature. Probability density functions are presented that aid in the
Monte-Carlo Tests Diplomarbeit
Monte-Carlo Tests Diplomarbeit Wiebke Werft Mathematisches Institut der Heinrich.2 Suffizienz und Vollständigkeit . . . . . . . . . . . . . . . . . . . . 5 2 Monte-Carlo Tests 8 2.1 Formulierung des Testproblems . . . . . . . . . . . . . . . . . . . 8 2.2 Definition des Monte-Carlo Tests
Sun, Sean
Metropolis Monte Carlo Sean X. Suna) and William H. Miller Department of Chemistry, University of California. The averaging of oscillatory integrals is converted into a Monte Carlo algorithm where one diffuses through in classical simulations such as importance sampling, biased sampling based on Monte Carlo MC techniques can
Jeong, Hee Jin; Kim, Ho Young; Jeong, Hyun; Han, Joong Tark; Jeong, Seung Yol; Baeg, Kang-Jun; Jeong, Mun Seok; Lee, Geon-Woong
2014-05-28
We present a straightforward method for simultaneously enhancing the electrical conductivity, environmental stability, and photocatalytic properties of graphene films through one-step transfer of CVD graphene and integration by introducing TiO2/graphene oxide layer. A highly durable and flexible TiO2 layer is successfully used as a supporting layer for graphene transfer instead of the commonly used PMMA. Transferred graphene/TiO2 film is directly used for measuring the carrier transport and optoelectronic properties without an extra TiO2 removal and following deposition steps for multifunctional integration into devices because the thin TiO2 layer is optically transparent and electrically semiconducting. Moreover, the TiO2 layer induces charge screening by electrostatically interacting with the residual oxygen moieties on graphene, which are charge scattering centers, resulting in a reduced current hysteresis. Adsorption of water and other chemical molecules onto the graphene surface is also prevented by the passivating TiO2 layer, resulting in the long term environmental stability of the graphene under high temperature and humidity. In addition, the graphene/TiO2 film shows effectively enhanced photocatalytic properties because of the increase in the transport efficiency of the photogenerated electrons due to the decrease in the injection barrier formed at the interface between the F-doped tin oxide and TiO2 layers. PMID:24578338
NSDL National Science Digital Library
David Liao
In this video, we become familiar with integrals, both by understanding them as sums of areas under plots of functions, and by understanding them as anti-derivatives. We present the u-substitution rule, which is the analog of the chain rule for differentiating composite functions.
NASA Astrophysics Data System (ADS)
Garcia, A.
2001-08-01
In the past decade a number of hybrid methods, which combine Direct Simulation Monte Carlo (DSMC) with computational fluid dynamics (CFD) algorithms, have been proposed. The motivation for developing such hybrids is primarily the computational expense of DSMC relative to continuum CFD schemes. After expanding on this motivation, specifically as it applies to microscopic flows, this talk will present a brief, chronological review of the various existing schemes. Elements common to all schemes (e.g., the choice of CFD algorithm, the creation of DSMC particles, the selection of the interface location, the numerical accuracy and stability of the coupling) will be discussed. Adaptive Mesh and Algorithm Refinement, a hybrid built with using framework of adaptive mesh refinement, will be presented in greater detail. Finally, future directions and challenges for particle/continuum hybrids will be outlined.
Powers, J J
2011-11-28
This study focused on creating a new tristructural isotropic (TRISO) coated particle fuel performance model and demonstrating the integration of this model into an existing system of neutronics and heat transfer codes, creating a user-friendly option for including fuel performance analysis within system design optimization and system-level trade-off studies. The end product enables both a deeper understanding and better overall system performance of nuclear energy systems limited or greatly impacted by TRISO fuel performance. A thorium-fueled hybrid fusion-fission Laser Inertial Fusion Energy (LIFE) blanket design was used for illustrating the application of this new capability and demonstrated both the importance of integrating fuel performance calculations into mainstream design studies and the impact that this new integrated analysis had on system-level design decisions. A new TRISO fuel performance model named TRIUNE was developed and verified and validated during this work with a novel methodology established for simulating the actual lifetime of a TRISO particle during repeated passes through a pebble bed. In addition, integrated self-consistent calculations were performed for neutronics depletion analysis, heat transfer calculations, and then fuel performance modeling for a full parametric study that encompassed over 80 different design options that went through all three phases of analysis. Lastly, side studies were performed that included a comparison of thorium and depleted uranium (DU) LIFE blankets as well as some uncertainty quantification work to help guide future experimental work by assessing what material properties in TRISO fuel performance modeling are most in need of improvement. A recommended thorium-fueled hybrid LIFE engine design was identified with an initial fuel load of 20MT of thorium, 15% TRISO packing within the graphite fuel pebbles, and a 20cm neutron multiplier layer with beryllium pebbles in flibe molten salt coolant. It operated at a system power level of 2000 MW{sub th}, took about 3.5 years to reach full plateau power, and was capable of an End of Plateau burnup of 38.7 %FIMA if considering just the neutronic constraints in the system design; however, fuel performance constraints led to a maximum credible burnup of 12.1 %FIMA due to a combination of internal gas pressure and irradiation effects on the TRISO materials (especially PyC) leading to SiC pressure vessel failures. The optimal neutron spectrum for the thorium-fueled blanket options evaluated seemed to favor a hard spectrum (low but non-zero neutron multiplier thicknesses and high TRISO packing fractions) in terms of neutronic performance but the fuel performance constraints demonstrated that a significantly softer spectrum would be needed to decrease the rate of accumulation of fast neutron fluence in order to improve the maximum credible burnup the system could achieve.
Fiedoruk, Marta; Cocovi-Solberg, David J; Tymecki, ?ukasz; Koncki, Robert; Miró, Manuel
2015-02-01
An integrated Sequential Injection (SI)/Flow Injection (FI) system furnished with a miniaturized LED-based fluorometric detector is presented in this work for expedient bioaccessibility tests of orthophosphate in soils. Equipped with a microcolumn of conical shape containing 50 mg of soil, the hybrid flow system was resorted to on-line dynamic leaching and real-time quantification of pools of mobilizable orthophosphate using a bi-directional syringe pump and multiposition valve. The flexibility of the flow manifold was harnessed to explore both bi-directional and uni-directional flow extraction modes with the added degree of freedom of on-line dilution of extracts whenever needed. Bioaccessible orthophosphate was split in three fractions, the so-called NH4Cl fraction containing labile exchangeable phosphates, the alkaline fraction with Fe and Al-bound phosphates and the acidic fraction containing Ca-bound phosphates. The prevailing molybdenum blue photometric detection method is replaced by spectrofluorometric detection based on the ion pair formation between the phosphomolybdate heteropolyacid and rhodamine B with the subsequent quenching of the dye fluorescence. The dedicated optoelectronic detector was integrated in a secondary FI manifold and operated according to the fluorometric paired emitter-detector diode (FPEDD) principle involving two light emitting diodes as fluorescence inductors and one as detector of LED-induced fluorescence. Demonstrated with the analysis of a standard reference material (SRM 2711) and a real agricultural soil, the developed FI/SI fractionation system with FPEDD detection is proven reliable against the standard molybdenum blue method (p>0.05), and useful for investigation of the leaching kinetics of orthophosphate in bioaccessibility tests through in-line recording of the extraction profiles. PMID:25435227
Yoon, Ki-Hong; Oh, Su Hwan; Kim, Ki Soo; Kwon, O-Kyun; Oh, Dae Kon; Noh, Young-Ouk; Lee, Hyung-Jong
2010-03-15
We presented a hybridly-integrated tunable external cavity laser with 0.8 nm mode spacing 16 channels operating in the direct modulation of 2.5-Gbps for a low-cost source of a WDM-PON system. The tunable laser was fabricated by using a superluminescent diode (SLD) and a polymer Bragg reflector. The maximum output power and the power slope efficiency of the tunable laser were 10.3 mW and 0.132 mW/mA, respectively, at the SLD current of 100 mA and the temperature of 25 degrees C. The directly-modulated tunable laser successfully provided 2.5-Gbps transmissions through 20-km standard single mode fiber. The power penalty of the tunable laser was less than 0.8 dB for 16 channels after a 20-km transmission. The power penalty variation was less than 1.4 dB during the blue-shifted wavelength tuning. PMID:20389571
Cramer, S.N.
1984-01-01
The MORSE code is a large general-use multigroup Monte Carlo code system. Although no claims can be made regarding its superiority in either theoretical details or Monte Carlo techniques, MORSE has been, since its inception at ORNL in the late 1960s, the most widely used Monte Carlo radiation transport code. The principal reason for this popularity is that MORSE is relatively easy to use, independent of any installation or distribution center, and it can be easily customized to fit almost any specific need. Features of the MORSE code are described.
Monte Carlo methods Monte Carlo Principle and MCMC
Doucet, Arnaud
Monte Carlo methods Monte Carlo Principle and MCMC A. Doucet Carcans Sept. 2011 A. Doucet (MLSS Sept. 2011) MCMC Sept. 2011 1 / 91 #12;Overview of the Lectures 1 Monte Carlo Principles A. Doucet (MLSS Sept. 2011) MCMC Sept. 2011 2 / 91 #12;Overview of the Lectures 1 Monte Carlo Principles 2 Markov
Anne Stary; Alain Sarasin
1992-01-01
We analysed the DNA rearrangements that occurred during the integration and amplification of an Epstein- Barr virus (EBV)-simian virus 40 (SV40) hybrid shuttle vector in human cells. The human HeLa cell line was episomally transformed with the EBV-SV40 p205-GTI plasmid. After a 2 month culture in a selective medium, a HeLa cell-derived population (H-G1 cells) was obtained in which the
Enhancements in Continuous-Energy Monte Carlo Capabilities in SCALE
Bekar, Kursat B [ORNL] [ORNL; Celik, Cihangir [ORNL] [ORNL; Wiarda, Dorothea [ORNL] [ORNL; Peplow, Douglas E. [ORNL] [ORNL; Rearden, Bradley T [ORNL] [ORNL; Dunn, Michael E [ORNL] [ORNL
2013-01-01
Monte Carlo tools in SCALE are commonly used in criticality safety calculations as well as sensitivity and uncertainty analysis, depletion, and criticality alarm system analyses. Recent improvements in the continuous-energy data generated by the AMPX code system and significant advancements in the continuous-energy treatment in the KENO Monte Carlo eigenvalue codes facilitate the use of SCALE Monte Carlo codes to model geometrically complex systems with enhanced solution fidelity. The addition of continuous-energy treatment to the SCALE Monaco code, which can be used with automatic variance reduction in the hybrid MAVRIC sequence, provides significant enhancements, especially for criticality alarm system modeling. This paper describes some of the advancements in continuous-energy Monte Carlo codes within the SCALE code system.
NASA Astrophysics Data System (ADS)
Kwak, Eunju
The development of sensor technologies and the increase in user requirements have resulted in many different approaches for efficient building model generation. Three-dimensional building models are important in various applications, such as disaster management and urban planning. Despite this importance, generation of these models lacks economical and reliable techniques which take advantage of the available multi-sensory data from single and multiple platforms. Therefore, this research develops a framework for fully-automated building model generation by integrating data-driven and model-driven methods as well as exploiting the advantages of images and LiDAR datasets. The building model generation starts by employing LiDAR data for building detection and approximate boundary determination. The generated building boundaries are then integrated into a model-based image processing strategy, because LiDAR derived planes show irregular boundaries due to the nature of LiDAR point acquisition. The focus of the research is generating models for the buildings with right-angled-corners, which can be described with a collection of rectangles (e.g., L-shape, T-shape, U-shape, gable roofs, and more complex building shapes which are combinations of the aforementioned shapes), under the assumption that the majority of the buildings in urban areas belong to this category. Therefore, by applying the Minimum Bounding Rectangle (MBR) algorithm recursively, the LiDAR boundaries are decomposed into sets of rectangles for further processing. At the same time the quality of the MBRs are examined to verify that the buildings, from which the boundaries are generated, are buildings with right-angled-corners. These rectangles are preliminary model primitives. The parameters that define the model primitives are adjusted using detected edges in the imagery through the least-squares adjustment procedure, i.e., model-based image fitting. The level of detail in the final Digital Building Model is based on the number of recursions during the MBR processing, which in turn are determined by the LiDAR point density. The model-based image fitting refines the search space and resolves the matching ambiguities in multiple images, which results in higher quality boundaries. This research thus develops an approach which not only automates the building model generation, but also improves the accuracy of the building model itself.
Interchange Format for Hybrid Systems: Abstract Semantics
Carloni, Luca
Interchange Format for Hybrid Systems: Abstract Semantics Alessandro Pinto1 , Luca P. Carloni3] we advocated the need for an interchange format for hybrid systems that enables the integration interchange format. In doing so, we clearly separate the structure of a hybrid system from the semantics
Hybrid Traffic Simulation with Adaptive Signal Control
Wilco Burghout; Johan Wahlstedt
2007-01-01
A hybrid mesoscopic–microscopic model is implemented that applies microscopic simulation to areas of specific interest while simulating a large surrounding network in lesser detail with a mesoscopic model. The hybrid model integrates VisSim, a microscopic traffic simulation model, and Mezzo, a recently developed mesoscopic model. The hybrid model is applied on a network in which Mezzo simulates the entire area
High-coherence semiconductor lasers based on integral high-Q resonators in hybrid Si/III-V platforms
Santis, Christos Theodoros; Steger, Scott T.; Vilenchik, Yaakov; Vasilyev, Arseny; Yariv, Amnon
2014-01-01
The semiconductor laser (SCL) is the principal light source powering the worldwide optical fiber network. The ever-increasing demand for data is causing the network to migrate to phase-coherent modulation formats, which place strict requirements on the temporal coherence of the light source that no longer can be met by current SCLs. This failure can be traced directly to the canonical laser design, in which photons are both generated and stored in the same, optically lossy, III-V material. This leads to an excessive and large amount of noisy spontaneous emission commingling with the laser mode, thereby degrading its coherence. High losses also decrease the amount of stored optical energy in the laser cavity, magnifying the effect of each individual spontaneous emission event on the phase of the laser field. Here, we propose a new design paradigm for the SCL. The keys to this paradigm are the deliberate removal of stored optical energy from the lossy III-V material by concentrating it in a passive, low-loss material and the incorporation of a very high-Q resonator as an integral (i.e., not externally coupled) part of the laser cavity. We demonstrate an SCL with a spectral linewidth of 18 kHz in the telecom band around 1.55 ?m, achieved using a single-mode silicon resonator with Q of 106. PMID:24516134
Santis, Christos Theodoros; Steger, Scott T; Vilenchik, Yaakov; Vasilyev, Arseny; Yariv, Amnon
2014-02-25
The semiconductor laser (SCL) is the principal light source powering the worldwide optical fiber network. The ever-increasing demand for data is causing the network to migrate to phase-coherent modulation formats, which place strict requirements on the temporal coherence of the light source that no longer can be met by current SCLs. This failure can be traced directly to the canonical laser design, in which photons are both generated and stored in the same, optically lossy, III-V material. This leads to an excessive and large amount of noisy spontaneous emission commingling with the laser mode, thereby degrading its coherence. High losses also decrease the amount of stored optical energy in the laser cavity, magnifying the effect of each individual spontaneous emission event on the phase of the laser field. Here, we propose a new design paradigm for the SCL. The keys to this paradigm are the deliberate removal of stored optical energy from the lossy III-V material by concentrating it in a passive, low-loss material and the incorporation of a very high-Q resonator as an integral (i.e., not externally coupled) part of the laser cavity. We demonstrate an SCL with a spectral linewidth of 18 kHz in the telecom band around 1.55 ?m, achieved using a single-mode silicon resonator with Q of 10(6). PMID:24516134
Monte Carlo variance reduction
NASA Technical Reports Server (NTRS)
Byrn, N. R.
1980-01-01
Computer program incorporates technique that reduces variance of forward Monte Carlo method for given amount of computer time in determining radiation environment in complex organic and inorganic systems exposed to significant amounts of radiation.
Arnold Flores
1986-01-01
A hybrid connector is presented whereby both electrical and fiber optic cables are connected to a printed circuit card. The connector consists of a female half which contains a plurality of fiber optic contact inserts molded into the connector, and also female electrical connections. The male half of the connector is an integral part of a printed circuit card constructed
B. Rekiek; A. Delchambre
2001-01-01
This paper presents a method to address the multiple objective hybrid assembly line balancing problem. The aim is to assign a set of tasks to stations and select equipment to perform each of them. The goal is to minimize the total cost of the line by integrating design (station space, equipment cost, etc.) and operation issues (cycle time, precedence constraints
Geometric Ergodicity and Hybrid Markov Chains Gareth O. Roberts* and Jeffrey S. Rosenthal**
Rosenthal, Jeffrey S.
Geometric Ergodicity and Hybrid Markov Chains by Gareth O. Roberts* and Jeffrey S. Rosenthal them. We then apply these results to a collection of chains commonly used in Markov chain Monte Carlo simulation algorithms, the soÂcalled hybrid chains. We prove that under certain conditions, a hybrid chain
MODELING AND ANALYSIS OF STOCHASTIC HYBRID SYSTEMS Jo~ao P. Hespanha
Hespanha, João Pedro
of the results obtained is evaluated through comparisons with Monte Carlo simulations. I. INTRODUCTION Hybrid1 MODELING AND ANALYSIS OF STOCHASTIC HYBRID SYSTEMS Jo~ao P. Hespanha Center for Control@ece.ucsb.edu http://www.ece.ucsb.edu/~hespanha Abstract The author describes a model for Stochastic Hybrid Systems
Hybrid fitness across time and habitats Michael L. Arnold1
Aspbury, Andrea S. - Department of Biology, Texas State University
Hybrid fitness across time and habitats Michael L. Arnold1 and Noland H. Martin2 1 Department in the evolutionary process. One question has involved the relative fitness of hybrid versus non-hybrid genotypes. For some, the assumption of lower hybrid fitness continues to be integral to their concept of species
NASA Astrophysics Data System (ADS)
Robinson, Patrick J.
Gasification has been used in industry on a relatively limited scale for many years, but it is emerging as the premier unit operation in the energy and chemical industries. The switch from expensive and insecure petroleum to solid hydrocarbon sources (coal and biomass) is occurring due to the vast amount of domestic solid resources, national security and global warming issues. Gasification (or partial oxidation) is a vital component of "clean coal" technology. Sulfur and nitrogen emissions can be reduced, overall energy efficiency is increased and carbon dioxide recovery and sequestration are facilitated. Gasification units in an electric power generation plant produce a fuel gas for driving combustion turbines. Gasification units in a chemical plant generate synthesis gas, which can be used to produce a wide spectrum of chemical products. Future plants are predicted to be hybrid power/chemical plants with gasification as the key unit operation. The coupling of an Integrated Gasification Combined Cycle (IGCC) with a methanol plant can handle swings in power demand by diverting hydrogen gas from a combustion turbine and synthesis gas from the gasifier to a methanol plant for the production of an easily-stored, hydrogen-consuming liquid product. An additional control degree of freedom is provided with this hybrid plant, fundamentally improving the controllability of the process. The idea is to base-load the gasifier and use the more responsive gas-phase units to handle disturbances. During the summer days, power demand can fluctuate up to 50% over a 12-hour period. The winter provides a different problem where spikes of power demand can go up 15% within the hour. The following dissertation develops a hybrid IGCC / methanol plant model, validates the steady-state results with a National Energy Technical Laboratory study, and tests a proposed control structure to handle these significant disturbances. All modeling was performed in the widely used chemical process simulators Aspen Plus and Aspen Dynamics. This dissertation first presents a simple approximate method for achieving the objective of having a gasifier model that can be exported into Aspen Dynamics. Limitations in the software dealing with solids make this a necessary task. The basic idea is to use a high molecular weight hydrocarbon that is present in the Aspen library as a pseudo fuel. For many plantwide dynamic studies, a rigorous high-fidelity dynamic model of the gasifier is not needed because its dynamics are very fast and the gasifier gas volume is a relatively small fraction of the total volume of the entire plant. The proposed approximate model captures the essential macro-scale thermal, flow, composition and pressure dynamics. This paper does not attempt to optimize the design or control of gasifiers, but merely presents an idea of how to dynamically simulate coal gasification in an approximate way. This dissertation also presents models of the downstream units of a typical IGCC. Dynamic simulations of the H2S absorption/stripping unit, Water-gas Shift (WGS) reactors, and CO2 absorption/stripping unit are essential for the development of stable and agile plantwide control structures of this hybrid power/chemical plant. Due to the high pressure of the system, hydrogen sulfide is removed by means of physical absorption. SELEXOLRTM (a mixture of the dimethyl ethers of polyethylene glycol) is used to achieve a gas purity of less than 5 ppm H2S. This desulfurized synthesis gas is sent to two water gas shift reactors that convert a total of 99% of carbon monoxide to hydrogen. Physical absorption of carbon dioxide with Selexol produces a hydrogen rich stream (90 mol% H2) to be fed into combustion turbines or to a methanol plant. Steady-state economic designs and plantwide control structures are developed in this dissertation. A steady-state economic design, control structure, and successful turndown of the methanol plant are shown in this dissertation. The Plantwide control structure and interaction among units are also shown. The methanol plant was si
Boltzmann bias grand canonical Monte Carlo
NASA Astrophysics Data System (ADS)
Garberoglio, G.
2008-04-01
We derive an efficient method for the insertion of structured particles in grand canonical Monte Carlo simulations of adsorption in very confining geometries. We extend this method to path integral simulations and use it to calculate the isotherm of adsorption of hydrogen isotopes in narrow carbon nanotubes (two-dimensional confinement) and slit pores (one-dimensional confinement) at the temperatures of 20 and 77 K, discussing its efficiency by comparison to the standard path integral grand canonical Monte Carlo algorithm. We use this algorithm to perform multicomponent simulations in order to calculate the hydrogen isotope selectivity for adsorption in narrow carbon nanotubes and slit pores at finite pressures. The algorithm described here can be applied to the study of adsorption of real oligomers and polymers in narrow pores and channels.
Hybridization of a sigma-delta-based CMOS hybrid detector Kolb, K.E.a
Figer, Donald F.
Hybridization of a sigma-delta-based CMOS hybrid detector Kolb, K.E.a ; Stoffel, N.C.c , Douglas, B-Out Integrated Circuit). The hybridized detector will have low noise, low power dissipation, low mass, Zeljkoe a Rochester Imaging Detector Lab, Rochester Institute of Technology, 54 Lomb Memorial Dr., 76- A
Chen, Ray
/polymer hybrid slot photonic crystal wave- guide modulators for on chip applications are presented. Recently-temperature process and wet- coating process of large areas suitable for almost all kinds of substrates are key
Filippone, W.L.; Baker, R.S. [Arizona Univ., Tucson, AZ (United States)
1990-12-31
The neutron transport equation is solved by a hybrid method that iteratively couples regions where deterministic (S{sub N}) and stochastic (Monte Carlo) methods are applied. Unlike previous hybrid methods, the Monte Carlo and S{sub N} regions are fully coupled in the sense that no assumption is made about geometrical separation or decoupling. The hybrid method provides a new means of solving problems involving both optically thick and optically thin regions that neither Monte Carlo nor S{sub N} is well suited for by themselves. The fully coupled Monte Carlo/S{sub N} technique consists of defining spatial and/or energy regions of a problem in which either a Monte Carlo calculation or an S{sub N} calculation is to be performed. The Monte Carlo region may comprise the entire spatial region for selected energy groups, or may consist of a rectangular area that is either completely or partially embedded in an arbitrary S{sub N} region. The Monte Carlo and S{sub N} regions are then connected through the common angular boundary fluxes, which are determined iteratively using the response matrix technique, and volumetric sources. The hybrid method has been implemented in the S{sub N} code TWODANT by adding special-purpose Monte Carlo subroutines to calculate the response matrices and volumetric sources, and linkage subrountines to carry out the interface flux iterations. The common angular boundary fluxes are included in the S{sub N} code as interior boundary sources, leaving the logic for the solution of the transport flux unchanged, while, with minor modifications, the diffusion synthetic accelerator remains effective in accelerating S{sub N} calculations. The special-purpose Monte Carlo routines used are essentially analog, with few variance reduction techniques employed. However, the routines have been successfully vectorized, with approximately a factor of five increase in speed over the non-vectorized version.
NASA Astrophysics Data System (ADS)
Tomczak, M.; Dubieniecki, P.
2015-04-01
On the basis of the Solar Maximum Mission observations, Švestka (Solar Phys. 121, 399, 1989) introduced a new class of flares, the so-called flare hybrids. When they start, they look like typical compact flares (phase 1), but later on, they look like flares with arcades of magnetic loops (phase 2). We summarize the characteristic features of flare hybrids in soft and hard X-rays as well as in the extreme ultraviolet; these features allow us to distinguish flare hybrids from other flares. In this article, additional energy release or long plasma cooling timescales are suggested as possible causes of phase 2. We estimate the frequency of flare hybrids, and study the magnetic configurations favorable for flare hybrid occurrence. Flare hybrids appear to be quite frequent, and the difference between the lengths of magnetic loops in the two interacting loop systems seem to be a crucial parameter for determining their characteristics.
Public Infrastructure for Monte Carlo Simulation : publicMCatBATAN
NASA Astrophysics Data System (ADS)
Waskita, A. A.; Prasetyo, N. A.; Akbar, Z.; Handoko, L. T.
2010-06-01
The first cluster-based public computing for Monte Carlo simulation in Indonesia is introduced. The system has been developed to enable public to perform Monte Carlo simulation on a parallel computer through an integrated and user friendly dynamic web interface. The beta version, so called publicMC@BATAN, has been released and implemented for internal users at the National Nuclear Energy Agency (BATAN). In this paper the concept and architecture of publicMC@BATAN are presented.
Shell model Monte Carlo calculations for Dy-170
D. J. Dean; S. E. Koonin; G. H. Lang; P. B. Radha; W. E. Ormand
1993-09-28
We present the first auxiliary field Monte Carlo calculations for a rare earth nucleus, Dy-170. A pairing plus quadrupole Hamiltonian is used to demonstrate the physical properties that can be studied in this region. We calculate various static observables for both uncranked and cranked systems and show how the shape distribution evolves with temperature. We also introduce a discretization of the path integral that allows a more efficient Monte Carlo sampling.
Quantum Monte Carlo Helsinki 2011
Boyer, Edmond
Quantum Monte Carlo Helsinki 2011 Marius Lewerenz MSME/CT, UMR 8208 CNRS, Universit´e Paris Est? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 What is a Monte Carlo method? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 What are Monte Carlo methods good for? . . . . . . . . . . . . . . . . . . . . . . . 5 1
Tan, Li; Jiang, Hongbo; Wang, Ying; Wei, Sheng; Nie, Shaofa
2014-01-01
Background Outbreaks of hand-foot-mouth disease (HFMD) have been reported for many times in Asia during the last decades. This emerging disease has drawn worldwide attention and vigilance. Nowadays, the prevention and control of HFMD has become an imperative issue in China. Early detection and response will be helpful before it happening, using modern information technology during the epidemic. Method In this paper, a hybrid model combining seasonal auto-regressive integrated moving average (ARIMA) model and nonlinear auto-regressive neural network (NARNN) is proposed to predict the expected incidence cases from December 2012 to May 2013, using the retrospective observations obtained from China Information System for Disease Control and Prevention from January 2008 to November 2012. Results The best-fitted hybrid model was combined with seasonal ARIMA and NARNN with 15 hidden units and 5 delays. The hybrid model makes the good forecasting performance and estimates the expected incidence cases from December 2012 to May 2013, which are respectively ?965.03, ?1879.58, 4138.26, 1858.17, 4061.86 and 6163.16 with an obviously increasing trend. Conclusion The model proposed in this paper can predict the incidence trend of HFMD effectively, which could be helpful to policy makers. The usefulness of expected cases of HFMD perform not only in detecting outbreaks or providing probability statements, but also in providing decision makers with a probable trend of the variability of future observations that contains both historical and recent information. PMID:24893000
Kundu, Debasis
likelihood estimators, asymptotic distribution, Bayes estimators, hybrid censoring, Markov chain Monte CarloIEEE TRANSACTIONS ON RELIABILITY, VOL. 57, NO. 2, JUNE 2008 369 Inference Based on Type-II Hybrid Censored Data From a Weibull Distribution Aveek Banerjee and Debasis Kundu Abstract--A hybrid censoring
Ceragioli, Francesca
we present a hybrid particle-grid Monte Carlo method for the Boltzmann equation, whichA hybrid method for hydrodynamic-kinetic flow - Part I - A particle-grid method for reducing is characterized by a significant reduction of the stochastic noise in the kinetic regime. The hybrid method
Monte Carlo results for the hydrogen Hugoniot.
Bezkrovniy, V; Filinov, V S; Kremp, D; Bonitz, M; Schlanges, M; Kraeft, W D; Levashov, P R; Fortov, V E
2004-11-01
We propose a theoretical Hugoniot relation obtained by combining results for the equation of state from the direct path integral Monte Carlo technique (DPIMC) and those from reaction ensemble Monte Carlo (REMC) simulations. The main idea of this proposal is based on the fact that the DPMIC technique provides first-principle results for a wide range of densities and temperatures including the region of partially ionized plasmas. On the other hand, for lower temperatures where the formation of molecules becomes dominant, DPIMC simulations become cumbersome and inefficient. For this region it is possible to use accurate REMC simulations where bound states (molecules) are treated on the Born-Oppenheimer level. The remaining interaction is then reduced to the scattering between neutral particles which is reliably treated classically by applying effective potentials. The resulting Hugoniot is located between the experimental values of Knudson et al. [Phys. Rev. Lett. 87, 225501 (2001)] and Collins et al. [Science 281, 1178 (1998)]. PMID:15600800
Quest, K.B.
1987-01-01
The philosophy and numerical implementation of hybrid algorithms are reviewed. In the hybrid approximation, a plasma is described by a set of discrete equations, equivalent to a Vlasov-fluid system. The dynamics of one or more species are modeled using moment equations, while the remaining species are treated as a large number of individual macro-particles. In this paper the hybrid method will be compared to fluid and particle-in-cell algorithms, and the strengths and weaknesses of the various methods will be discussed. A specific limit of the hybrid model, that of macro-particle ions and massless, charge-neutralizing fluid electrons, will be analyzed in detail with particular emphasis on multi-dimensional codes.
Advances in the modeling of single electron transistors for the design of integrated circuit.
Chi, Yaqing; Sui, Bingcai; Yi, Xun; Fang, Liang; Zhou, Hailiang
2010-09-01
Single electron transistor (SET) has become a promising candidate for the key device of logic circuit in the near future. The advances of recent 5 years in the modeling of SETs are reviewed for the simulation of SET/hybrid CMOS-SET integrated circuit. Three dominating SET models, Monte Carlo model, master equation model and macro model, are analyzed, tested and compared on their principles, characteristics, applicability and development trend. The Monte Carlo model is suitable for SET structure research and simulation of small scale SET circuit, while the analytical model based on combination with master equation and macro model is suitable to simulate the SET circuit at balanceable efficiency and accuracy. PMID:21133161
Chin, P.W. [Department of Medical Physics, Velindre Cancer Centre, Velindre Road, Cardiff CF14 2TL (United Kingdom)]. E-mail: mary.chin@physics.org
2005-10-15
This project developed a solution for verifying external photon beam radiotherapy. The solution is based on a calibration chain for deriving portal dose maps from acquired portal images, and a calculation framework for predicting portal dose maps. Quantitative comparison between acquired and predicted portal dose maps accomplishes both geometric (patient positioning with respect to the beam) and dosimetric (two-dimensional fluence distribution of the beam) verifications. A disagreement would indicate that beam delivery had not been according to plan. The solution addresses the clinical need for verifying radiotherapy both pretreatment (without the patient in the beam) and on treatment (with the patient in the beam). Medical linear accelerators mounted with electronic portal imaging devices (EPIDs) were used to acquire portal images. Two types of EPIDs were investigated: the amorphous silicon (a-Si) and the scanning liquid ion chamber (SLIC). The EGSnrc family of Monte Carlo codes were used to predict portal dose maps by computer simulation of radiation transport in the beam-phantom-EPID configuration. Monte Carlo simulations have been implemented on several levels of high throughput computing (HTC), including the grid, to reduce computation time. The solution has been tested across the entire clinical range of gantry angle, beam size (5 cmx5 cm to 20 cmx20 cm), and beam-patient and patient-EPID separations (4 to 38 cm). In these tests of known beam-phantom-EPID configurations, agreement between acquired and predicted portal dose profiles was consistently within 2% of the central axis value. This Monte Carlo portal dosimetry solution therefore achieved combined versatility, accuracy, and speed not readily achievable by other techniques.
Hybrid Solar Vehicles: Perspectives, Problems, Management Strategies
Ivan Arsie; Gianfranco Rizzo; Marco Sorrentino
Hybrid Solar Vehicles (HSV), derived by integration of Hybrid Electric Vehicles with Photo-Voltaic sources, may represent a valuable solution to face both energy saving and environmental issues, particularly in urban driving. Previous studies have also shown that economic feasibility could be achieved in a near future. After a presentation of the perspectives and the problems related to the use of
Design and Optimization of Future Hybrid and Electric Propulsion Systems
Paris-Sud XI, Université de
Design and Optimization of Future Hybrid and Electric Propulsion Systems: An Advanced Tool and Optimization of Future Hybrid and Electric Propulsion Systems: An Advanced Tool Integrated in a Complete systèmes de propulsion hybride et électrique: un outil avancé et intégré dans une chaîne complète dédiée à
40 CFR 1036.525 - Hybrid engines.
Code of Federal Regulations, 2014 CFR
2014-07-01
...system (RESS) and the power electronics between the hybrid electric...work done over the cycle. Use W cycle as the integrated...the brake energy fraction. W neg = the negative work over the cycle. W pos = the positive...
40 CFR 1036.525 - Hybrid engines.
Code of Federal Regulations, 2013 CFR
2013-07-01
...system (RESS) and the power electronics between the hybrid electric...work done over the cycle. Use W cycle as the integrated...the brake energy fraction. W neg = the negative work over the cycle. W pos = the positive...
40 CFR 1036.525 - Hybrid engines.
Code of Federal Regulations, 2012 CFR
2012-07-01
...system (RESS) and the power electronics between the hybrid electric...work done over the cycle. Use W cycle as the integrated...the brake energy fraction. W neg = the negative work over the cycle. W pos = the positive...
Monte Carlo errors with less errors
NASA Astrophysics Data System (ADS)
Wolff, Ulli; Alpha Collaboration
2004-01-01
We explain in detail how to estimate mean values and assess statistical errors for arbitrary functions of elementary observables in Monte Carlo simulations. The method is to estimate and sum the relevant autocorrelation functions, which is argued to produce more certain error estimates than binning techniques and hence to help toward a better exploitation of expensive simulations. An effective integrated autocorrelation time is computed which is suitable to benchmark efficiencies of simulation algorithms with regard to specific observables of interest. A Matlab code is offered for download that implements the method. It can also combine independent runs (replica) allowing to judge their consistency.
Monte Carlo Generation of Bohmian Trajectories
T. M. Coffey; R. E. Wyatt; W. C. Schieve
2008-07-01
We report on a Monte Carlo method that generates one-dimensional trajectories for Bohm's formulation of quantum mechanics that doesn't involve differentiation or integration of any equations of motion. At each time, t=n\\delta t (n=1,2,3,...), N particle positions are randomly sampled from the quantum probability density. Trajectories are built from the sorted N sampled positions at each time. These trajectories become the exact Bohm solutions in the limits N->\\infty and \\delta t -> 0. Higher dimensional problems can be solved by this method for separable wave functions. Several examples are given, including the two-slit experiment.
Monte Carlo and Quasi-Monte Carlo algorithms for the Barker-Ferry equation with low
Whitlock, Paula
Monte Carlo and Quasi-Monte Carlo algorithms for the Barker-Ferry equation with low complexity ? T. The quasi-Monte Carlo (QMC) solutions obtained by QRNs are compared with the Monte Carlo (MC) solutions) converges [3] and the solution can be evaluated by a MC estimator. 2 Monte Carlo and Quasi-Monte Carlo
Practical Markov Chain Monte Carlo
Charles J. Geyer
1992-01-01
Markov chain Monte Carlo using the Metropolis-Hastings algorithm is a general method for the simulation of stochastic processes having probability densities known up to a constant of proportionality. Despite recent advances in its theory, the practice has remained controversial. This article makes the case for basing all inference on one long run of the Markov chain and estimating the Monte
Compartment fire risk analysis by advanced Monte Carlo simulation
Siu Kui Au; Zhi-Hua Wang; Siu-Ming Lo
2007-01-01
Quantitative fire risk analysis aims at providing an assessment of fire safety on a scientific basis and taking relevant uncertainties into account in a rational quantitative manner. Under a probabilistic approach, performance measures are formulated as multi-dimensional probability integrals, whose efficient computation is pivotal for practical implementation. Direct Monte Carlo method is a well-known technique, but it is not efficient
MAGNETIC PROPERTIES OF MAGHEMITE: A HEISENBERG-MONTE CARLO APPROACH
J. Restrepo
Magnetic properties of bulk maghemite are addressed by means of the Monte Carlo method in the framework of a three dimensional classical Heisenberg model with cubic crystalline anisotropy. The crystalline structure has been simulated in the most realistic way and different sets of exchan- ge integrals have been taken from literature in order to check their influence upon the magnetic
Variance Reduction Techniques for Monte Carlo Sampling from Student Distributions
Daniel A. Relles
1970-01-01
A Monte Carlo design is presented for estimating the variance and cumulative distribution function of translation and scale invariant statistics based on independent Student random variables. One obvious application is studying estimates of the location parameter from a symmetric, possibly long-tailed distribution. The method itself amounts to suppressing some of the variability in the sampled objects by integrating these objects
Cao, Shaomei; Feng, Xin; Song, Yuanyuan; Xue, Xin; Liu, Hongjiang; Miao, Miao; Fang, Jianhui; Shi, Liyi
2015-05-27
A free-standing lithium titanate (Li4Ti5O12)/carbon nanotube/cellulose nanofiber hybrid network film is successfully assembled by using a pressure-controlled aqueous extrusion process, which is highly efficient and easily to scale up from the perspective of disposable and recyclable device production. This hybrid network film used as a lithium-ion battery (LIB) electrode has a dual-layer structure consisting of Li4Ti5O12/carbon nanotube/cellulose nanofiber composites (hereinafter referred to as LTO/CNT/CNF), and carbon nanotube/cellulose nanofiber composites (hereinafter referred to as CNT/CNF). In the heterogeneous fibrous network of the hybrid film, CNF serves simultaneously as building skeleton and a biosourced binder, which substitutes traditional toxic solvents and synthetic polymer binders. Of importance here is that the CNT/CNF layer is used as a lightweight current collector to replace traditional heavy metal foils, which therefore reduces the total mass of the electrode while keeping the same areal loading of active materials. The free-standing network film with high flexibility is easy to handle, and has extremely good conductivity, up to 15.0 S cm(-1). The flexible paper-electrode for LIBs shows very good high rate cycling performance, and the specific charge/discharge capacity values are up to 142 mAh g(-1) even at a current rate of 10 C. On the basis of the mild condition and fast assembly process, a CNF template fulfills multiple functions in the fabrication of paper-electrode for LIBs, which would offer an ever increasing potential for high energy density, low cost, and environmentally friendly flexible electronics. PMID:25938940
NASA Astrophysics Data System (ADS)
Flores, Arnold
1986-07-01
A hybrid connector is presented whereby both electrical and fiber optic cables are connected to a printed circuit card. The connector consists of a female half which contains a plurality of fiber optic contact inserts molded into the connector, and also female electrical connections. The male half of the connector is an integral part of a printed circuit card constructed to contain male fiber optical contact inserts in addition to the standard plated electrical male type contact points. Both halves of the connector may be fitted with removable and interchangeable fiber optic contacts, radio frequency contacts, and/or power pins in addition to the standard printed circuit card contacts for wire wrap or solder connections. The printed circuit card hybrid fiber optic connector presented here provides normal card installation and removal of fiber optic interconnects from standard card cages or other boards without threading or other special engaging mechanisms.
Pajunen, Maria; Turakainen, Hilkka; Poussu, Eini; Peränen, Johan; Vihinen, Mauno; Savilahti, Harri
2007-01-01
Understanding networks of protein–protein interactions constitutes an essential component on a path towards comprehensive description of cell function. Whereas efficient techniques are readily available for the initial identification of interacting protein partners, practical strategies are lacking for the subsequent high-resolution mapping of regions involved in protein–protein interfaces. We present here a genetic strategy to accurately map interacting protein regions at amino acid precision. The system is based on parallel construction, sampling and analysis of a comprehensive insertion mutant library. The methodology integrates Mu in vitro transposition-based random pentapeptide mutagenesis of proteins, yeast two-hybrid screening and high-resolution genetic footprinting. The strategy is general and applicable to any interacting protein pair. We demonstrate the feasibility of the methodology by mapping the region in human JFC1 that interacts with Rab8A, and we show that the association is mediated by the Slp homology domain 1. PMID:17702760
Nonlinear hybrid Boltzmannparticle-in-cell acceleration algorithm K. L. Cartwright,a)
Wurtele, Jonathan
Nonlinear hybrid Boltzmannparticle-in-cell acceleration algorithm K. L. Cartwright,a) J. P scales. Hybrid electrostatic particle-in-cell PIC algorithms are presented in which most of the electrons distribution. Collisions for PIC electrons are included via a Monte Carlo model, while for the MB electrons
Monte Carlo Eikonal Scattering
NASA Astrophysics Data System (ADS)
Gibbs, W. R.; Dedonder, J.-P.
2011-04-01
Eikonal multiple scattering theory in the form of the Glauber model is believed to be accurate for high-energy elastic scattering of heavy-ion systems. The evaluation of the full expression has only been done for the lightest systems with recourse often being made to an optical model model approximation. We evaluate the full expression without further approximation using a Monte Carlo representation of the nuclear density including the center-of-mass and Coulomb corrections. The center-of-mass correction remains very important for all nuclei investigated. The input to these calculations is the basic NN amplitude, characterized by four parameters, and the nuclear density. We have made calculations of a number of cases of elastic scattering using NN parameters taken from the VPI/GWU fits. Results of several calculations will be shown and compared with data.
A new method to assess Monte Carlo convergence
Forster, R.A.; Booth, T.E.; Pederson, S.P.
1993-05-01
The central limit theorem can be applied to a Monte Carlo solution if the following two requirements are satisfied: (1) the random variable has a finite mean and a finite variance; and (2) the number N of independent observations grows large. When these are satisfied, a confidence interval based on the normal distribution with a specified coverage probability can be formed. The first requirement is generally satisfied by the knowledge of the type of Monte Carlo tally being used. The Monte Carlo practitioner has only a limited number of marginally quantifiable methods that use sampled values to assess the fulfillment of the second requirement; e.g., statistical error reduction proportional to 1{radical}N with error magnitude guidelines. No consideration is given to what has not yet been sampled. A new method is presented here to assess the convergence of Monte Carlo solutions by analyzing the shape of the empirical probability density function (PDF) of history scores, f(x), where the random variable x is the score from one particle history and {integral}{sub {minus}{infinity}}{sup {infinity}} f(x) dx = 1. Since f(x) is seldom known explicitly, Monte Carlo particle random walks sample f(x) implicitly. Unless there is a largest possible history score, the empirical f(x) must eventually decrease more steeply than l/x{sup 3} for the second moment ({integral}{sub {minus}{infinity}}{sup {infinity}} x{sup 2}f(x) dx) to exist.
Gisler, Serge M.; Kittanakom, Saranya; Fuster, Daniel; Wong, Victoria; Bertic, Mia; Radanovic, Tamara; Hall, Randy A.; Murer, Heini; Biber, Jürg; Markovich, Daniel; Moe, Orson W.; Stagljar, Igor
2008-01-01
PDZ-binding motifs are found in the C-terminal tails of numerous integral membrane proteins where they mediate specific protein-protein interactions by binding to PDZ-containing proteins. Conventional yeast two-hybrid screens have been used to probe protein-protein interactions of these soluble C termini. However, to date no in vivo technology has been available to study interactions between the full-length integral membrane proteins and their cognate PDZ-interacting partners. We previously developed a split-ubiquitin membrane yeast two-hybrid (MYTH) system to test interactions between such integral membrane proteins by using a transcriptional output based on cleavage of a transcription factor from the C terminus of membrane-inserted baits. Here we modified MYTH to permit detection of C-terminal PDZ domain interactions by redirecting the transcription factor moiety from the C to the N terminus of a given integral membrane protein thus liberating their native C termini. We successfully applied this “MYTH 2.0” system to five different mammalian full-length renal transporters and identified novel PDZ domain-containing partners of the phosphate (NaPi-IIa) and sulfate (NaS1) transporters that would have otherwise not been detectable. Furthermore this assay was applied to locate the PDZ-binding domain on the NaS1 protein. We showed that the PDZ-binding domain for PDZK1 on NaS1 is upstream of its C terminus, whereas the two interacting proteins, NHERF-1 and NHERF-2, bind at a location closer to the N terminus of NaS1. Moreover NHERF-1 and NHERF-2 increased functional sulfate uptake in Xenopus oocytes when co-expressed with NaS1. Finally we used MYTH 2.0 to demonstrate that the NaPi-IIa transporter homodimerizes via protein-protein interactions within the lipid bilayer. In summary, our study establishes the MYTH 2.0 system as a novel tool for interactive proteomics studies of membrane protein complexes. PMID:18407958
Monte Carlo Capabilities of the SCALE Code System
NASA Astrophysics Data System (ADS)
Rearden, B. T.; Petrie, L. M.; Peplow, D. E.; Bekar, K. B.; Wiarda, D.; Celik, C.; Perfetti, C. M.; Ibrahim, A. M.; Hart, S. W. D.; Dunn, M. E.
2014-06-01
SCALE is a widely used suite of tools for nuclear systems modeling and simulation that provides comprehensive, verified and validated, user-friendly capabilities for criticality safety, reactor physics, radiation shielding, and sensitivity and uncertainty analysis. For more than 30 years, regulators, licensees, and research institutions around the world have used SCALE for nuclear safety analysis and design. SCALE provides a "plug-and-play" framework that includes three deterministic and three Monte Carlo radiation transport solvers that can be selected based on the desired solution, including hybrid deterministic/Monte Carlo simulations. SCALE includes the latest nuclear data libraries for continuous-energy and multigroup radiation transport as well as activation, depletion, and decay calculations. SCALE's graphical user interfaces assist with accurate system modeling, visualization, and convenient access to desired results. SCALE 6.2, to be released in 2014, will provide several new capabilities and significant improvements in many existing features, especially with expanded continuous-energy Monte Carlo capabilities for criticality safety, shielding, depletion, and sensitivity and uncertainty analysis. An overview of the Monte Carlo capabilities of SCALE is provided here, with emphasis on new features for SCALE 6.2.
Parallelizing Monte Carlo with PMC
Rathkopf, J.A.; Jones, T.R.; Nessett, D.M.; Stanberry, L.C.
1994-11-01
PMC (Parallel Monte Carlo) is a system of generic interface routines that allows easy porting of Monte Carlo packages of large-scale physics simulation codes to Massively Parallel Processor (MPP) computers. By loading various versions of PMC, simulation code developers can configure their codes to run in several modes: serial, Monte Carlo runs on the same processor as the rest of the code; parallel, Monte Carlo runs in parallel across many processors of the MPP with the rest of the code running on other MPP processor(s); distributed, Monte Carlo runs in parallel across many processors of the MPP with the rest of the code running on a different machine. This multi-mode approach allows maintenance of a single simulation code source regardless of the target machine. PMC handles passing of messages between nodes on the MPP, passing of messages between a different machine and the MPP, distributing work between nodes, and providing independent, reproducible sequences of random numbers. Several production codes have been parallelized under the PMC system. Excellent parallel efficiency in both the distributed and parallel modes results if sufficient workload is available per processor. Experiences with a Monte Carlo photonics demonstration code and a Monte Carlo neutronics package are described.
Plastic biochannel hybridization devices: a new concept for microfluidic DNA arrays
Ralf Lenigk; Robin H Liu; Mahesh Athavale; Zhijian Chen; Dale Ganser; Jianing Yang; Cory Rauch; Yingjie Liu; Betty Chan; Huinan Yu; Melissa Ray; Robert Marrero; Piotr Grodzinski
2002-01-01
Conventional DNA hybridization assay kinetics depends solely on the diffusion of target to surface-bound probes, causing long hybridization times. In this study, we examined the possibilities of accelerating the hybridization process by using microfluidic channels (“biochannels”) made of polycarbonate, optionally with an integrated pump. We produced two different devices to study these effects: first, hybridization kinetics was investigated by using
Eulerian-Lagrangian relationships in Monte Carlo simulations of turbulent diffusion
Lee, J.T.; Stone, G.L.
1983-01-01
The results of this study show that Monte Carlo simulations of diffusion in homogeneous turbulence can be formulated in terms of the Eulerian space-time velocity autocorrelation function. Numerical results obtained using this approach agree with results obtained by Taylor (1921) using the Lagrangian autocorrelation function. Use was made of the equivalence of the Lagrangian and Eulerian Monte Carlo approaches to derive analytic relations between the Lagrangian integral time scale and the Eulerian integral space and time scales. These analytic results were verified by comparison to Monte Carlo simulations and to other theoretical results. They are in general agreement with many existing theories and semi-empirical relations.
Multiscale kinetic Monte Carlo algorithm for simulating epitaxial growth
NASA Astrophysics Data System (ADS)
Devita, Jason P.; Sander, Leonard M.; Smereka, Peter
2005-11-01
We present a fast Monte Carlo algorithm for simulating epitaxial surface growth, based on the continuous-time Monte Carlo algorithm of Bortz, Kalos, and Lebowitz. When simulating realistic growth regimes, much computational time is consumed by the relatively fast dynamics of the adatoms. Continuum and continuum-discrete hybrid methods have been developed to approach this issue; however, in many situations, the density of adatoms is too low to efficiently and accurately simulate as a continuum. To solve the problem of fast adatom dynamics, we allow adatoms to take larger steps, effectively reducing the number of transitions required. We achieve nearly a factor of ten speed up, for growth at moderate temperatures and large D/F .
Modelling cerebral blood oxygenation using Monte Carlo XYZ-PA
NASA Astrophysics Data System (ADS)
Zam, Azhar; Jacques, Steven L.; Alexandrov, Sergey; Li, Youzhi; Leahy, Martin J.
2013-02-01
Continuous monitoring of cerebral blood oxygenation is critically important for the management of many lifethreatening conditions. Non-invasive monitoring of cerebral blood oxygenation with a photoacoustic technique offers advantages over current invasive and non-invasive methods. We introduce a Monte Carlo XYZ-PA to model the energy deposition in 3D and the time-resolved pressures and velocity potential based on the energy absorbed by the biological tissue. This paper outlines the benefits of using Monte Carlo XYZ-PA for optimization of photoacoustic measurement and imaging. To the best of our knowledge this is the first fully integrated tool for photoacoustic modelling.
Wormhole Hamiltonian Monte Carlo
Lan, Shiwei; Streets, Jeffrey; Shahbaba, Babak
2015-01-01
In machine learning and statistics, probabilistic inference involving multimodal distributions is quite difficult. This is especially true in high dimensional problems, where most existing algorithms cannot easily move from one mode to another. To address this issue, we propose a novel Bayesian inference approach based on Markov Chain Monte Carlo. Our method can effectively sample from multimodal distributions, especially when the dimension is high and the modes are isolated. To this end, it exploits and modifies the Riemannian geometric properties of the target distribution to create wormholes connecting modes in order to facilitate moving between them. Further, our proposed method uses the regeneration technique in order to adapt the algorithm by identifying new modes and updating the network of wormholes without affecting the stationary distribution. To find new modes, as opposed to redis-covering those previously identified, we employ a novel mode searching algorithm that explores a residual energy function obtained by subtracting an approximate Gaussian mixture density (based on previously discovered modes) from the target density function. PMID:25861551
NASA Astrophysics Data System (ADS)
Karioja, Pentti; Mäkinen, Jukka-Tapani; Keränen, Kimmo; Aikio, Janne; Alajoki, Teemu; Jaakola, Tuomo; Koponen, Matti; Keränen, Antti; Heikkinen, Mikko; Tuomikoski, Markus; Suhonen, Riikka; Hakalahti, Leena; Kopola, Pälvi; Hast, Jukka; Liedert, Ralf; Hiltunen, Jussi; Masuda, Noriyuki; Kemppainen, Antti; Rönkä, Kari; Korhonen, Raimo
2012-04-01
This paper presents research activities carried out at VTT Technical Research Centre of Finland in the field of hybrid integration of optics, electronics and mechanics. Main focus area in our research is the manufacturing of electronic modules and product structures with printed electronics, film-over-molding and polymer sheet lamination technologies and the goal is in the next generation of smart systems utilizing monolithic polymer packages. The combination of manufacturing technologies such as roll-to-roll -printing, injection molding and traditional component assembly is called Printed Hybrid Systems (PHS). Several demonstrator structures have been made, which show the potential of polymer packaging technology. One demonstrator example is a laminated structure with embedded LED chips. Element thickness is only 0.3mm and the flexible stack of foils can be bent in two directions after assembly process and was shaped curved using heat and pressure. The combination of printed flexible circuit boards and injection molding has also been demonstrated with several functional modules. The demonstrators illustrate the potential of origami electronics, which can be cut and folded to 3D shapes. It shows that several manufacturing process steps can be eliminated by Printed Hybrid Systems technology. The main benefits of this combination are small size, ruggedness and conformality. The devices are ideally suited for medical applications as the sensitive electronic components are well protected inside the plastic and the structures can be cleaned easily due to the fact that they have no joints or seams that can accumulate dirt or bacteria.
Monte Carlo discretization of general relativistic radiation transport
Burkhard Zink
2012-12-11
An indirect, hybrid Monte Carlo discretization of general relativistic kinetic theory suitable for the development of numerical schemes for radiation transport is presented. The discretization is based on surface flux estimators obtained from a local decomposition of the distribution function, and can handle optically thick regions by means of formal solutions within each cell. Furthermore, the scheme is designed for parallel implementation, and it admits the use of adaptive techniques by virtue of leaving all probability density functions unspecified. Some considerations for numerical uses of the scheme are discussed.
Monte Carlo Methods for Inference and Learning
Hinton, Geoffrey E.
Monte Carlo Methods for Inference and Learning Guest Lecturer: Ryan Adams CSC 2535 http://www.cs.toronto.edu/~rpa #12;Overview ·Monte Carlo basics ·Rejection and Importance sampling ·Markov chain Monte Carlo ·Metropolis-Hastings and Gibbs sampling ·Slice sampling ·Hamiltonian Monte Carlo #12;Computing Expectations We
Monte Carlo Simulation of Interacting Electron Models
Robinson, Robert W.
Monte Carlo Simulation of Interacting Electron Models by a New Determinant Approach by Mucheng discusses the calculation of determinants and Monte Carlo simulation of Hub- bard models by a new and a Monte Carlo summation algorithm to evaluate the relevant diagram determinant sums. Index words: Monte
SPQR: a Monte Carlo reactor kinetics code. [LMFBR
Cramer, S.N.; Dodds, H.L.
1980-02-01
The SPQR Monte Carlo code has been developed to analyze fast reactor core accident problems where conventional methods are considered inadequate. The code is based on the adiabatic approximation of the quasi-static method. This initial version contains no automatic material motion or feedback. An existing Monte Carlo code is used to calculate the shape functions and the integral quantities needed in the kinetics module. Several sample problems have been devised and analyzed. Due to the large statistical uncertainty associated with the calculation of reactivity in accident simulations, the results, especially at later times, differ greatly from deterministic methods. It was also found that in large uncoupled systems, the Monte Carlo method has difficulty in handling asymmetric perturbations.