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1

Rotational fluctuation of molecules in quantum clusters. I. Path integral hybrid Monte Carlo algorithm  

SciTech Connect

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.

Miura, Shinichi [Institute for Molecular Science, 38 Myodaiji, Okazaki 444-8585 (Japan)

2007-03-21

2

Testing and tuning symplectic integrators for the hybrid Monte Carlo algorithm in lattice QCD  

SciTech Connect

We examine a new second-order integrator recently found by Omelyan et al. The integration error of the new integrator measured in the root mean square of the energy difference, <{delta}H{sup 2}>{sup 1/2}, is about 10 times smaller than that of the standard second-order leapfrog (2LF) integrator. As a result, the step size of the new integrator can be made about three times larger. Taking into account a factor 2 increase in cost, the new integrator is about 50% more efficient than the 2LF integrator. Integrating over positions first, then momenta, is slightly more advantageous than the reverse. Further parameter tuning is possible. We find that the optimal parameter for the new integrator is slightly different from the value obtained by Omelyan et al., and depends on the simulation parameters. This integrator could also be advantageous for the Trotter-Suzuki decomposition in quantum Monte Carlo.

Takaishi, Tetsuya [Hiroshima University of Economics, Hiroshima 731-0124 (Japan); Forcrand, Philippe de [Physics Department, CERN, TH Unit, CH-1211 Geneva 23 (Switzerland); Institute for Theoretical Physics, ETH Zuerich, CH-8093 Zurich (Switzerland)

2006-03-15

3

Compressible generalized hybrid Monte Carlo  

NASA Astrophysics Data System (ADS)

One of the most demanding calculations is to generate random samples from a specified probability distribution (usually with an unknown normalizing prefactor) in a high-dimensional configuration space. One often has to resort to using a Markov chain Monte Carlo method, which converges only in the limit to the prescribed distribution. Such methods typically inch through configuration space step by step, with acceptance of a step based on a Metropolis(-Hastings) criterion. An acceptance rate of 100% is possible in principle by embedding configuration space in a higher dimensional phase space and using ordinary differential equations. In practice, numerical integrators must be used, lowering the acceptance rate. This is the essence of hybrid Monte Carlo methods. Presented is a general framework for constructing such methods under relaxed conditions: the only geometric property needed is (weakened) reversibility; volume preservation is not needed. The possibilities are illustrated by deriving a couple of explicit hybrid Monte Carlo methods, one based on barrier-lowering variable-metric dynamics and another based on isokinetic dynamics.

Fang, Youhan; Sanz-Serna, J. M.; Skeel, Robert D.

2014-05-01

4

Compressible generalized hybrid Monte Carlo.  

PubMed

One of the most demanding calculations is to generate random samples from a specified probability distribution (usually with an unknown normalizing prefactor) in a high-dimensional configuration space. One often has to resort to using a Markov chain Monte Carlo method, which converges only in the limit to the prescribed distribution. Such methods typically inch through configuration space step by step, with acceptance of a step based on a Metropolis(-Hastings) criterion. An acceptance rate of 100% is possible in principle by embedding configuration space in a higher dimensional phase space and using ordinary differential equations. In practice, numerical integrators must be used, lowering the acceptance rate. This is the essence of hybrid Monte Carlo methods. Presented is a general framework for constructing such methods under relaxed conditions: the only geometric property needed is (weakened) reversibility; volume preservation is not needed. The possibilities are illustrated by deriving a couple of explicit hybrid Monte Carlo methods, one based on barrier-lowering variable-metric dynamics and another based on isokinetic dynamics. PMID:24811626

Fang, Youhan; Sanz-Serna, J M; Skeel, Robert D

2014-05-01

5

Hybrid path integral Monte Carlo simulation of rigid diatomic molecules: effect of quantized rotations on the selectivity of hydrogen isotopes in carbon nanotubes  

Microsoft Academic Search

We present a multiple time step algorithm for hybrid path integral Monte Carlo simulations involving rigid linear rotors. We show how to calculate the quantum torques needed in the simulation from the rotational density matrix, for which we develop an approximate expression suitable in the case of heteronuclear molecules. We use this method to study the effect of rotational quantization

Giovanni Garberoglio; J. K. Johnson

2007-01-01

6

Efficient ab initio path integral hybrid Monte Carlo based on the fourth-order Trotter expansion: Application to fluoride ion-water cluster.  

PubMed

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(-)(H(2)O) and F(-)(D(2)O), at ambient temperature, particularly focusing on the geometrical isotope effect. PMID:20405986

Suzuki, Kimichi; Tachikawa, Masanori; Shiga, Motoyuki

2010-04-14

7

Efficient ab initio path integral hybrid Monte Carlo based on the fourth-order Trotter expansion: Application to fluoride ion-water cluster  

NASA Astrophysics Data System (ADS)

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.

Suzuki, Kimichi; Tachikawa, Masanori; Shiga, Motoyuki

2010-04-01

8

Quasi-Monte Carlo Integration  

NASA Astrophysics Data System (ADS)

The standard Monte Carlo approach to evaluating multidimensional integrals using (pseudo)-random integration nodes is frequently used when quadrature methods are too difficult or expensive to implement. As an alternative to the random methods, it has been suggested that lower error and improved convergence may be obtained by replacing the pseudo-random sequences with more uniformly distributed sequences known as quasi-random. In this paper quasi-random (Halton, Sobol', and Faure) and pseudo-random sequences are compared in computational experiments designed to determine the effects on convergence of certain properties of the integrand, including variance, variation, smoothness, and dimension. The results show that variation, which plays an important role in the theoretical upper bound given by the Koksma-Hlawka inequality, does not affect convergence, while variance, the determining factor in random Monte Carlo, is shown to provide a rough upper bound, but does not accurately predict performance. In general, quasi-Monte Carlo methods are superior to random Monte Carlo, but the advantage may be slight, particularly in high dimensions or for integrands that are not smooth. For discontinuous integrands, we derive a bound which shows that the exponent for algebraic decay of the integration error from quasi-Monte Carlo is only slightly larger than {1}/{2} in high dimensions.

Morokoff, William J.; Caflisch, Russel E.

1995-12-01

9

A separable shadow Hamiltonian hybrid Monte Carlo method.  

PubMed

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

Sweet, Christopher R; Hampton, Scott S; Skeel, Robert D; Izaguirre, Jesús A

2009-11-01

10

A separable shadow Hamiltonian hybrid Monte Carlo method  

NASA Astrophysics Data System (ADS)

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).

Sweet, Christopher R.; Hampton, Scott S.; Skeel, Robert D.; Izaguirre, Jesús A.

2009-11-01

11

Wavelet formulation of path integral Monte Carlo  

Microsoft Academic Search

A wavelet formulation of path integral Monte Carlo (PIMC) is constructed. Comparison with Fourier path integral Monte Carlo is presented using simple one-dimensional examples. Wavelet path integral Monte Carlo exhibits a few advantages over previous methods for PIMC. The efficiency of the current method is at least comparable to other techniques.

Art E. Cho; J. D. Doll; David L. Freeman

2002-01-01

12

Beating the Verlet integrator in Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

We propose a new methodology for constructing integrators to simulate Hamiltonian dynamics within Hybrid Monte Carlo and related algorithms. The algorithms based on the new approach are minor modifications of the standard Verlet integrator that nevertheless provide very substantial savings in computational cost.

Blanes, S.; Casas, F.; Sanz-Serna, J. M.

2013-10-01

13

Hybrid optofluidic integration.  

PubMed

Complete integration of microfluidic and optical functions in a single lab-on-chip device is one goal of optofluidics. Here, we demonstrate the hybrid integration of a PDMS-based fluid handling layer with a silicon-based optical detection layer in a single optofluidic system. The optical layer consists of a liquid-core antiresonant reflecting optical waveguide (ARROW) chip that is capable of single particle detection and interfacing with optical fiber. Integrated devices are reconfigurable and able to sustain high pressures despite the small dimensions of the liquid-core waveguide channels. We show the combination of salient sample preparation capabilities-particle mixing, distribution, and filtering-with single particle fluorescence detection. Specifically, we demonstrate fluorescent labelling of ?-DNA, followed by flow-based single-molecule detection on a single device. This points the way towards amplification-free detection of nucleic acids with low-complexity biological sample preparation on a chip. PMID:23969694

Parks, Joshua W; Cai, Hong; Zempoaltecatl, Lynnell; Yuzvinsky, Thomas D; Leake, Kaelyn; Hawkins, Aaron R; Schmidt, Holger

2013-10-21

14

Path integral Monte Carlo simulations of silicates  

Microsoft Academic Search

We investigate the thermal expansion of crystalline SiO2 in the beta-cristobalite and the beta-quartz structure with path integral Monte Carlo (PIMC) techniques. This simulation method allows to treat low-temperature quantum effects properly. At temperatures below the Debye temperature, thermal properties obtained with PIMC agree better with experimental results than those obtained with classical Monte Carlo methods.

Chr. Rickwardt; P. Nielaba; M. H. Müser; K. Binder

2001-01-01

15

A Primer in Monte Carlo Integration Using Mathcad  

ERIC Educational Resources Information Center

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…

Hoyer, Chad E.; Kegerreis, Jeb S.

2013-01-01

16

Path Integral Monte Carlo Calculation of Interatomic Forces  

Microsoft Academic Search

The calculation of electronic forces with quantum Monte Carlo has, for many years, been an outstanding problem. One can calculate interatomic forces with Path Integral Monte Carlo(PIMC) as the coordinate derivatives of the partition function. Advantages of using PIMC are that effects of thermal electronic excitations and correlations are included, no trial functions are involved and the force estimator is

Fenghua Zong; David Ceperley

1997-01-01

17

Green's function analysis of path integral Monte Carlo molecular simulations  

Microsoft Academic Search

We demonstrate the direct determination of molecular properties from path integral Monte Carlo simulations. By sampling Matsubura Green's functions, we have calculated several linear response properties of the hydrogen molecule (H2) directly from quantum Monte Carlo. We show that the vibration frequency of H2 as calculated directly from the phonon temperature Green's function is in very good agreement with the

Daejin Shin; John Shumway

2006-01-01

18

Bayesian Inference in Econometric Models Using Monte Carlo Integration  

Microsoft Academic Search

Methods for the systematic application of Monte Carlo integration with importance sampling to Bayesian inference are developed. Conditions under which the numerical approximation converges almost surely to the true value with the number of Monte Carlo replications, and its numerical accuracy may be assessed reliably, are given. Importance sampling densities are derived from multivariate normal or student approximations to the

John Geweke

1989-01-01

19

Path-Integral Monte Carlo Methods for Ultrasmall Device Modeling  

Microsoft Academic Search

Monte Carlo methods based on the Feynman path -integral (FPI) formulation of quantum mechanics are developed for modeling ultrasmall device structures. A brief introduction to pertinent aspects of the FPI formalism is given. A practical \\

Leonard Franklin Register II

1990-01-01

20

Path Integral Monte Carlo Simulation of Isotopic Liquid Helium Mixtures  

Microsoft Academic Search

We report results of a path integral Monte Carlo simulation of a liquid 3He- 4He mixture at low temperature. In the limit of low 3He concentration, a kinetic energy of 17 K is found for the 3He atoms; the 3He effective mass is m* = 2.3m. The restricted path integral Monte Carlo method was utilized to investigate the separation of

Massimo Boninsegni; David M. Ceperley

1995-01-01

21

Hybrid Monte Carlo algorithm with fat link fermion actions  

NASA Astrophysics Data System (ADS)

The use of APE smearing or other blocking techniques in lattice fermion actions can provide many advantages. There are many variants of these fat link actions in lattice QCD currently, such as flat link irrelevant clover (FLIC) fermions. The FLIC fermion formalism makes use of the APE blocking technique in combination with a projection of the blocked links back into the special unitary group. This reunitarization is often performed using an iterative maximization of a gauge invariant measure. This technique is not differentiable with respect to the gauge field and thus prevents the use of standard Hybrid Monte Carlo simulation algorithms. The use of an alternative projection technique circumvents this difficulty and allows the simulation of dynamical fat link fermions with standard HMC and its variants. The necessary equations of motion for FLIC fermions are derived, and some initial simulation results are presented. The technique is more general however, and is straightforwardly applicable to other smearing techniques or fat link actions.

Kamleh, Waseem; Leinweber, Derek B.; Williams, Anthony G.

2004-07-01

22

Path Integral Quantum Monte Carlo Benchmarks for Molecules and Plasmas  

NASA Astrophysics Data System (ADS)

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.

Shumway, John

2013-03-01

23

Numerical Pricing of Derivative Claims: Path Integral Monte Carlo Approach  

Microsoft Academic Search

We propose a path integral Monte Carlo method for pricing of derivative securities. Metropolisalgorithm is used to sample probability distribution of histories (paths) of the underlying security.The advantage of path integral approach is that complete information about the derivative security,including its parameter sensitivities is obtained in a single simulation. It is also possible to obtainresults for multiple values of parameters

Miloje S. Makivic

1994-01-01

24

ITER Neutronics Modeling Using Hybrid Monte Carlo/Deterministic and CAD-Based Monte Carlo Methods  

SciTech Connect

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.

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

25

Hybrid model of Monte Carlo simulation and diffusion theory for light reflectance by turbid media.  

PubMed

Light reflectance by semi-infinite turbid media is modeled by a hybrid of Monte Carlo simulation and diffusion theory, which combines the accuracy of Monte Carlo simulation near the source and the speed of diffusion theory distant from the source. For example, when the turbid medium has the following optical properties--absorption coefficient 1 cm-1, scattering coefficient 100 cm-1, anisotropy 0.9, and refractive-index-matched boundary--the hybrid simulation is 7 times faster than the pure Monte Carlo simulation (100,000 photon packets were traced), and the difference between the two simulations is within 2 standard deviations of the Monte Carlo simulation. PMID:8350159

Wang, L; Jacques, S L

1993-08-01

26

Hybrid Molecular Dynamics - Kinetic Monte Carlo Approach for the Simulation of the growth of Soot Precursors.  

National Technical Information Service (NTIS)

A new code, named Hybrid Molecular Dynamics--Kinetic Monte Carlo (Hybrid MD/KMC), has been developed and employed to analyze possible growth pathways that lead to high molecular mass compounds. The Hybrid MD-KMC code combines the strengths of two common s...

A. Violi A. Kubota T. N. Truong W. Pitz C. K. Westbrook A. F. Sarofim

2001-01-01

27

Recent progress on PLC hybrid integration  

NASA Astrophysics Data System (ADS)

Planar lightwave circuit (PLC) hybrid integration is a promising way to realizing low-cost and highly functional optical components which are integrated with opto-electronic (OE) devices. As low-cost components, WDM hybrid transceiver modules have been developed to construct the fiber-to-the- home networks. As highly functional optical components, a multi-wavelength light source, a high-speed optical wavelength selector and a differential photoreceiver module have been demonstrated to construct optical transmission and switching systems employing dense wavelength-division- multiplexing and time-division-multiplexing technologies. This paper reviews the current status and recent progress on the PLC hybrid integration.

Kato, Kuniharu; Inoue, Yasuyuki

1999-04-01

28

Path Integral Monte Carlo Simulation of Hot, Dense Hydrogen  

Microsoft Academic Search

Path integral Monte Carlo simulations have been applied to study the hot, dense hydrogen at Mega-bar pressures corresponding to the density and temperature range of 1 < rs < 14 and 5000 K < T < 1000000 K. We determine the equation of state and study the phase diagram including the molecular, atomic and plasma regime. We discuss the effects

Burkhard Militzer

2001-01-01

29

Path integral Monte Carlo for dissipative many-body systems  

Microsoft Academic Search

We address the possibility of performing numerical Monte Carlo simulations for the thermodynamics of quantum dissipative systems. Dissipation is considered within the Caldeira-Leggett formulation, which describes the system in the path-integral formalism through the inclusion of an influence action that is bilocal and quadratic in the system's coordinates. At a first sight the usual direct approach of discretizing the path

Luca Capriotti; Alessandro Cuccoli; Andrea Fubini; Valerio Tognetti; Ruggero Vaia

2003-01-01

30

a Path Integral Monte Carlo Method for the Quasielastic Response  

Microsoft Academic Search

We formulate the quasielastic response of a non -relativistic many-body system at zero temperature in terms of ground state density matrix elements and real time path integrals that embody the final state interactions. While the former provide the weight for a conventional Monte Carlo calculation, the latter require a more sophisticated treatment. We argue that the recently developed Stationary Phase

Carlo Carraro

1990-01-01

31

Global Optimization:  Quantum Thermal Annealing with Path Integral Monte Carlo  

Microsoft Academic Search

We investigate a new method (QTA-PIMC) for global optimization on complex potential energy surfaces which combines the path integral Monte Carlo method with quantum and thermal annealing. This method is applied to the BLN protein model (Honeycutt, J. D.; Thirumalai, D. Biopolymers 1992, 32, 695). We show that this new approach outperforms simulated (thermal) annealing (SA) and that in fact

Yong-Han Lee; B. J. Berne

2000-01-01

32

Path integral Monte Carlo simulations of hot dense hydrogen  

Microsoft Academic Search

Path integral Monte Carlo (PIMC) simulations are a powerful computational method to study interacting quantum systems at finite temperature. In this work, PIMC has been applied to study the equilibrium properties of hot, dense hydrogen in the temperature and density range of 5000 <= T <= 10 6K and 10--3 <= p <= 2.7gcm --3. We determine the equation of

Burkhard Militzer

2000-01-01

33

Path Integral Monte Carlo Calculation of the Deuterium Hugoniot  

Microsoft Academic Search

Restricted path integral Monte Carlo simulations have been used to calculate the equilibrium properties of deuterium for two densities: 0.674 and 0.838 g cm-3 ( rs = 2.00 and 1.86) in the temperature range of 105<=T<=106 K. We carefully assess size effects and dependence on the time step of the path integral. Further, we compare the results obtained with a

B. Militzer; D. M. Ceperley

2000-01-01

34

Path integral monte carlo simulations of H 2 surfaces  

Microsoft Academic Search

The (1,1, 1)-surfaces of bulk solid molecular hydrogen have been studied at temperatures between 0.5 K and 1.3 K, using path integral Monte Carlo. A general method is introduced for constructing an external potential to represent the tail correction for an arbitrary heterogeneous layered bulk substrate-adsorbate system. We compute density profiles parallel and perpendicular to the free H2 surface, total

Marcus Wagner; David M. Ceperley

1994-01-01

35

Path-integral Monte Carlo study of amorphous silicon  

Microsoft Academic Search

Amorphous silicon (a-Si) is studied by path-integral Monte Carlo simulations. These quantum atomistic simulations allow one to analyze the temperature dependence of the kinetic and potential contributions to the vibrational energy of the material, as well as the atomic mean-square displacements, further than the harmonic approximation. The results obtained for a-Si are compared with those found in similar quantum simulations

Carlos P. Herrero

2000-01-01

36

Path Integral Monte Carlo Studies of molecular parahydrogen clusters  

Microsoft Academic Search

Using the path integral Monte Carlo method, we have extensively studied para-hydrogen clusters, (pH_2)_N, with 6<= N <= 35 as a function of temperature. Small molecular para-hydrogen clusters are predicted to be superfluid at temperatures below about 2K. In view of recent experiments, we characterize the structual and energetic properties over the temperature range T = 1 - 10K using

Kwangsik Nho; Doerte Blume

2004-01-01

37

Monte Carlo integration with quasi-random numbers: some experience  

NASA Astrophysics Data System (ADS)

We report on our general experience and on some test calculations with quasi-random numbers of the Halton type applied to Monte Carlo integration in several (4-8) dimensions. Compared with the traditional use of (pseudo-)random numbers we find that, at a prescribed level of accuracy, at least one order of magnitude in computing time may be saved even for a step function integrand.

Berblinger, Michael; Schlier, Christoph

1991-09-01

38

Monte Carlo Modeling of an Integrating Sphere Reflectometer  

Microsoft Academic Search

The Monte Carlo method has been applied to numerical modeling of an integrating sphere designed for hemispherical-directional reflectance factor measurements. It is shown that a conventional algorithm of backward ray tracing used for estimation of characteristics of the radiation field at a given point has slow convergence for small source-to-sphere-diameter ratios. A newly developed algorithm that sub- stantially improves the

Alexander V. Prokhorov; Sergey N. Mekhontsev; Leonard M. Hanssen

2003-01-01

39

Path integral Monte Carlo on a lattice: extended states.  

PubMed

The equilibrium properties of a single quantum particle (qp) interacting with a classical gas for a wide range of temperatures that explore the system's behavior in the classical as well as in the quantum regime is investigated. Both the qp and atoms are restricted to the sites of a one-dimensional lattice. A path integral formalism is developed within the context of the canonical ensemble in which the qp is represented by a closed, variable-step random walk on the lattice. Monte Carlo methods are employed to determine the system's properties. For the case of a free particle, analytical expressions for the energy, its fluctuations, and the qp-qp correlation function are derived and compared with the Monte Carlo simulations. To test the usefulness of the path integral formalism, the Metropolis algorithm is employed to determine the equilibrium properties of the qp for a periodic interaction potential, forcing the qp to occupy extended states. We consider a striped potential in one dimension, where every other lattice site is occupied by an atom with potential ?, and every other lattice site is empty. This potential serves as a stress test for the path integral formalism because of its rapid site-to-site variation. An analytical solution was determined in this case by utilizing Bloch's theorem due to the periodicity of the potential. Comparisons of the potential energy, the total energy, the energy fluctuations, and the correlation function are made between the results of the Monte Carlo simulations and the analytical calculations. PMID:24827210

O'Callaghan, Mark; Miller, Bruce N

2014-04-01

40

Path integral Monte Carlo on a lattice: Extended states  

NASA Astrophysics Data System (ADS)

The equilibrium properties of a single quantum particle (qp) interacting with a classical gas for a wide range of temperatures that explore the system's behavior in the classical as well as in the quantum regime is investigated. Both the qp and atoms are restricted to the sites of a one-dimensional lattice. A path integral formalism is developed within the context of the canonical ensemble in which the qp is represented by a closed, variable-step random walk on the lattice. Monte Carlo methods are employed to determine the system's properties. For the case of a free particle, analytical expressions for the energy, its fluctuations, and the qp-qp correlation function are derived and compared with the Monte Carlo simulations. To test the usefulness of the path integral formalism, the Metropolis algorithm is employed to determine the equilibrium properties of the qp for a periodic interaction potential, forcing the qp to occupy extended states. We consider a striped potential in one dimension, where every other lattice site is occupied by an atom with potential ?, and every other lattice site is empty. This potential serves as a stress test for the path integral formalism because of its rapid site-to-site variation. An analytical solution was determined in this case by utilizing Bloch's theorem due to the periodicity of the potential. Comparisons of the potential energy, the total energy, the energy fluctuations, and the correlation function are made between the results of the Monte Carlo simulations and the analytical calculations.

O'Callaghan, Mark; Miller, Bruce N.

2014-04-01

41

Ferrite Elements for Hybrid Microwave Integrated Systems  

Microsoft Academic Search

Complete realization of the potentialities of hybrid microwave integrated circuits will require both semiconductor and ferrite elements. This paper presents performance data for several microstrip ferrite devices that can play an important role in the exploitation of microwave integrated circuits. Data on both fixed-field and latched microstrip junction circulators are given including a fixed-field circulator with less than 0.4-dB loss

J. LAMAR ALLEN; DONALD R. TAFT

1968-01-01

42

Ferrite elements for hybrid microwave integrated systems  

Microsoft Academic Search

Complete realization of the potentialities of hybrid microwave integrated circuits will require both semiconductor and ferrite elements. This paper presents performance data for several microstrip ferrite devices that can play an important role in the exploitation of microwave integrated circuits. Data on both fixed-field and latched microstrip junction circulators are given including a fixed-field circulator with less than 0.4- dB

J. L. Allen; D. R. Taft

1968-01-01

43

A hybrid device simulator that combines Monte Carlo and drift-diffusion analysis  

Microsoft Academic Search

A hybrid simulator suitable for modeling small semiconductor devices has been developed in which Monte Carlo and drift-diffusion models are combined. In critical device regions, the position-dependent coefficients of an extended drift-diffusion equation are extracted from a Monte Carlo simulation. Criteria for identifying these regions are described. Additional features which make the code more efficient are presented. First, a free-flight

Hans Kosina; Siegfried Selberherr

1994-01-01

44

Modified Hybrid Bronchoscope Tracking Based on Sequential Monte Carlo Sampler: Dynamic Phantom Validation  

Microsoft Academic Search

\\u000a This paper presents a new hybrid bronchoscope tracking method that uses an electromagnetic position sensor, a sequential Monte\\u000a Carlo sampler, and its evaluation on a dynamic motion phantom. Since airway deformation resulting from patient movement, respiratory\\u000a motion, and coughing can significantly affect the rigid registration between electromagnetic tracking and computed tomography\\u000a (CT) coordinate systems, a standard hybrid tracking approach that

Xióngbiao Luó; Tobias Reichl; Marco Feuerstein; Takayuki Kitasaka; Kensaku Mori

2010-01-01

45

Revisiting 1?+ Light Hybrid from Monte-Carlo Based QCD Sum Rules  

NASA Astrophysics Data System (ADS)

We reanalyze the 1?+ light hybrid from QCD sum rules with a Monte-Carlo based on uncertainty analysis. With 30% uncertainties in the accepted central values for QCD condensates and other input parameters, we obtain a prediction on the 1?+ hybrid mass of 1.71 ± 0.22 GeV, which covers the mass of ?1(1600). We also study the correlations between the input and output parameters of QCD sum rules.

Zhang, Zhu-Feng; Jin, Hong-Ying; G. Steele, T.

2014-05-01

46

The Local Hybrid Monte Carlo Algorithm for Free Field Theory: Reexamining Overrelaxation  

Microsoft Academic Search

We analyze the autocorrelations for the Local Hybrid Monte Carlo algorithm (1) in the context of free field theory. In this case this is just Adler's overrelaxation algorithm (2). We consider the algorithm with even\\/odd, lexicographic, and random updates, and show that its efficiency depends crucially on this ordering ofsites when optimized for a given class of operators. In particular,

Ivan Horvath; A. D. Kennedy

1987-01-01

47

A hybrid multiscale kinetic Monte Carlo method for simulation of copper electrodeposition  

Microsoft Academic Search

A hybrid multiscale kinetic Monte Carlo (HMKMC) method for speeding up the simulation of copper electrodeposition is presented. The fast diffusion events are simulated deterministically with a heterogeneous diffusion model which considers site-blocking effects of additives. Chemical reactions are simulated by an accelerated (tau-leaping) method for discrete stochastic simulation which adaptively selects exact discrete stochastic simulation for the appropriate reaction

Zheming Zheng; Ryan M. Stephens; Richard D. Braatz; Richard C. Alkire; Linda R. Petzold

2008-01-01

48

Path Integral Monte Carlo Simulation of Hot, Dense Hydrogen  

NASA Astrophysics Data System (ADS)

Path integral Monte Carlo simulations have been applied to study the hot, dense hydrogen at Mega-bar pressures corresponding to the density and temperature range of 1 < rs < 14 and 5000 K < T < 1000000 K. We determine the equation of state and study the phase diagram including the molecular, atomic and plasma regime. We discuss the effects of different fermion nodes, which we improved by developing a variational thermal density matrix [1]. Furthermore, we calculate the deuterium Hugoniot [2] and compare with shock wave experiments. [1] B. Militzer, E.L. Pollock, ``Variational Density Matrix Method for Warm Condensed Matter and Application to Dense Hydrogen'', Phys. Rev. E 61 (2000) 3470. [2] B. Militzer, D. M. Ceperley, "Path Integral Monte Carlo Calculation of the Deuterium Hugoniot", Phys. Rev. Lett. 85 (2000) 1890.

Militzer, Burkhard

2001-03-01

49

Path Integral Monte Carlo Calculation of the Deuterium Hugoniot  

SciTech Connect

Restricted path integral Monte Carlo simulations have been used to calculate the equilibrium properties of deuterium for two densities: 0.674 and 0.838 g cm {sup -3} (r{sub s}=2.00 and 1.86) in the temperature range of 10{sup 5}{<=}T{<=}10{sup 6} K . We carefully assess size effects and dependence on the time step of the path integral. Further, we compare the results obtained with a free particle nodal restriction with those from a self-consistent variational principle, which includes interactions and bound states. By using the calculated internal energies and pressures, we determine the shock Hugoniot and compare with recent laser shock wave experiments as well as other theories. (c) 2000 The American Physical Society.

Militzer, B.; Ceperley, D. M.

2000-08-28

50

All-Electron Path Integral Monte Carlo Simulations of Small Atoms and Molecules  

Microsoft Academic Search

Imaginary-time Feynman path integrals describe quantum mechanics at finite temperatures. Monte Carlo simulations using path integrals have many ap- plications to nanoscale physics. Fermions introduce negative terms in the partition function, which we remove with a fixed-node approximation. In this article, we give an introduction to path integral Monte Carlo simulations. We focus on a difficult problem: the direct application

J. Shumway

51

Local Coarse-Grained Approximation to Path Integral Monte Carlo Integration for Fermion Systems  

Microsoft Academic Search

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.

Deyan Sun

2010-01-01

52

Local Coarse-grained Approximation to Path Integral Monte Carlo Integration for Fermion Systems  

Microsoft Academic Search

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.

D. Y. Sun

2008-01-01

53

Longitudinal development of extensive air showers: Hybrid code SENECA and full Monte Carlo  

NASA Astrophysics Data System (ADS)

New experiments, exploring the ultra-high energy tail of the cosmic ray spectrum with unprecedented detail, are exerting a severe pressure on extensive air shower modelling. Detailed fast codes are in need in order to extract and understand the richness of information now available. Some hybrid simulation codes have been proposed recently to this effect (e.g., the combination of the traditional Monte Carlo scheme and system of cascade equations or pre-simulated air showers). In this context, we explore the potential of SENECA, an efficient hybrid tri-dimensional simulation code, as a valid practical alternative to full Monte Carlo simulations of extensive air showers generated by ultra-high energy cosmic rays. We extensively compare hybrid method with the traditional, but time consuming, full Monte Carlo code CORSIKA which is the de facto standard in the field. The hybrid scheme of the SENECA code is based on the simulation of each particle with the traditional Monte Carlo method at two steps of the shower development: the first step predicts the large fluctuations in the very first particle interactions at high energies while the second step provides a well detailed lateral distribution simulation of the final stages of the air shower. Both Monte Carlo simulation steps are connected by a cascade equation system which reproduces correctly the hadronic and electromagnetic longitudinal profile. We study the influence of this approach on the main longitudinal characteristics of proton, iron nucleus and gamma induced air showers and compare the predictions of the well known CORSIKA code using the QGSJET hadronic interaction model.

Ortiz, Jeferson A.; Medina-Tanco, Gustavo; de Souza, Vitor

2005-06-01

54

Hydrogen molecule ion: Path-integral Monte Carlo approach  

SciTech Connect

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.

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

55

Monte Carlo Simulations of Background Spectra in Integral Imager Detectors  

NASA Technical Reports Server (NTRS)

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.

Armstrong, T. W.; Colborn, B. L.; Dietz, K. L.; Ramsey, B. D.; Weisskopf, M. C.

1998-01-01

56

''Hybrid'' Monte Carlo simulation of ripple transport in stellarators  

SciTech Connect

A rapid simulation has been developed to accurately describe ripple effects on particle motion in stellarators at low collision frequencies. The majority of ripple trapped particles are followed through the iterative conservation of their bounce action J, while those particles in the region of phase space on either side of the ripple trap/detrap boundary are followed using guiding center equations. This ''hybrid'' formulation provides the most accurate numerical description of ripple trapped particle orbits to date, short of a fully guiding center code. This is important since these orbits are often substantially different from those allowed for in analytic theory and in other transport codes. Further, the hybrid simulation is much faster than a fully guiding center treatment, making all collision frequency regimes of interest accessible at reasonable costs of computer time. The methods employed allow the examination of stellarator configurations for which the magnitude of the toroidal well, epsilon/sub t/, is larger than that of the helical well, epsilon/sub h/, as well as configurations more often treated in which epsilon/sub h/ > epsilon/sub t/. Results are obtained for the usual analytic model of the helical ripple, epsilon/sub h/ = epsilon/sub h/(r), as well as a more realistic model for which epsilon/sub h/ = epsilon/sub h/(r,theta). The results are largely explainable in terms of existing analytic theories, although some slight modifications seem to be necessary.

Beidler, C.D.; Hitchon, W.N.G.; Shohet, J.L.

1986-02-01

57

A path integral Monte Carlo study of liquid neon and the quantum effective pair potential  

Microsoft Academic Search

The path integral Monte Carlo (PIMC) method is used to simulate liquid neon at T=40 K. It is shown that quantum effects are not negligible and that when the quantum effective pair potential is used in a classical molecular dynamics simulation the results obtained for the radial distribution function agrees with that predicted by a full path integral Monte Carlo

D. Thirumalai; Randall W. Hall; B. J. Berne

1984-01-01

58

Path integral Monte Carlo method and maximum entropy: a complete solution for the derivative valuation problem  

Microsoft Academic Search

Summary form only given. We propose a combination of the path-integral Monte Carlo method and the maximum entropy method as a comprehensive solution for the problem of pricing of derivative securities. The path-integral Monte Carlo approach relies on the probability distribution of the complete histories of the underlying security, from the present time to the contract expiration date. In our

M. S. Makivic

1996-01-01

59

A hybrid multiscale kinetic Monte Carlo method for simulation of copper electrodeposition  

SciTech Connect

A hybrid multiscale kinetic Monte Carlo (HMKMC) method for speeding up the simulation of copper electrodeposition is presented. The fast diffusion events are simulated deterministically with a heterogeneous diffusion model which considers site-blocking effects of additives. Chemical reactions are simulated by an accelerated (tau-leaping) method for discrete stochastic simulation which adaptively selects exact discrete stochastic simulation for the appropriate reaction whenever that is necessary. The HMKMC method is seen to be accurate and highly efficient.

Zheng Zheming [Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106 (United States); Stephens, Ryan M.; Braatz, Richard D.; Alkire, Richard C. [Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Petzold, Linda R. [Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106 (United States)], E-mail: petzold@cs.ucsb.edu

2008-05-01

60

The Local Hybrid Monte Carlo algorithm for free field theory: Reexamining overrelaxation  

Microsoft Academic Search

We analyze the autocorrelations for the Local Hybrid Monte Carlo algorithm [A.D. Kennedy, Nucl. Phys. B (Proc. Suppl.) 30 (1993) 96] in the context of free field theory. In this case this is just Adler's overrelaxation algorithm [S.L. Adler, Phys. Rev. D 23 (1981) 2901]. We consider the algorithm with even\\/odd, lexicographic, and random updates, and show that its efficiency

Ivan Horváth; A. D. Kennedy

1998-01-01

61

Hybrid asynchronous algorithm for parallel kinetic Monte Carlo simulations of thin film growth  

Microsoft Academic Search

We have generalized and implemented the hybrid asynchronous algorithm, originally proposed for parallel simulations of the spin-flip Ising model, in order to carry out parallel kinetic Monte Carlo (KMC) simulations. The parallel performance has been tested using a simple model of thin-film growth in both 1D and 2D. We also briefly describe how the data collection must be modified as

Yunsic Shim; Jacques G.. Amar

2006-01-01

62

A Hybrid EM and Monte Carlo EM Algorithm and Its Application to Analysis of Transmission of Infectious Diseases  

PubMed Central

Summary In epidemics of infectious diseases such as influenza, an individual may have one of four possible final states: prior immune, escaped from infection, infected with symptoms, and infected asymptomatically. The exact state is often not observed. In addition, the unobserved transmission times of asymptomatic infections further complicate analysis. Under the assumption of missing at random, data-augmentation techniques can be used to integrate out such uncertainties. We adapt an importance-sampling-based Monte Carlo EM (MCEM) algorithm to the setting of an infectious disease transmitted in close contact groups. Assuming the independence between close contact groups, we propose a hybrid EM-MCEM algorithm that applies the MCEM or the traditional EM algorithms to each close contact group depending on the dimension of missing data in that group, and discuss the variance estimation for this practice. In addition, we propose a bootstrap approach to assess the total Monte Carlo error and factor that error into the variance estimation. The proposed methods are evaluated using simulation studies. We use the hybrid EM-MCEM algorithm to analyze two influenza epidemics in the late 1970s to assess the effects of age and pre-season antibody levels on the transmissibility and pathogenicity of the viruses.

Yang, Yang; Longini, Ira M.; Halloran, M. Elizabeth; Obenchain, Valerie

2012-01-01

63

A hybrid EM and Monte Carlo EM algorithm and its application to analysis of transmission of infectious diseases.  

PubMed

In epidemics of infectious diseases such as influenza, an individual may have one of four possible final states: prior immune, escaped from infection, infected with symptoms, and infected asymptomatically. The exact state is often not observed. In addition, the unobserved transmission times of asymptomatic infections further complicate analysis. Under the assumption of missing at random, data-augmentation techniques can be used to integrate out such uncertainties. We adapt an importance-sampling-based Monte Carlo Expectation-Maximization (MCEM) algorithm to the setting of an infectious disease transmitted in close contact groups. Assuming the independence between close contact groups, we propose a hybrid EM-MCEM algorithm that applies the MCEM or the traditional EM algorithms to each close contact group depending on the dimension of missing data in that group, and discuss the variance estimation for this practice. In addition, we propose a bootstrap approach to assess the total Monte Carlo error and factor that error into the variance estimation. The proposed methods are evaluated using simulation studies. We use the hybrid EM-MCEM algorithm to analyze two influenza epidemics in the late 1970s to assess the effects of age and preseason antibody levels on the transmissibility and pathogenicity of the viruses. PMID:22506893

Yang, Yang; Longini, Ira M; Halloran, M Elizabeth; Obenchain, Valerie

2012-12-01

64

CAD-based Monte Carlo Program for Integrated Simulation of Nuclear System SuperMC  

NASA Astrophysics Data System (ADS)

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.

Wu, Yican; Song, Jing; Zheng, Huaqing; Sun, Guangyao; Hao, Lijuan; Long, Pengcheng; Hu, Liqin

2014-06-01

65

High order Chin actions in path integral Monte Carlo.  

PubMed

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 H(2) drop, and bulk liquid (4)He. 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 (4)He. PMID:19485439

Sakkos, K; Casulleras, J; Boronat, J

2009-05-28

66

High order Chin actions in path integral Monte Carlo  

SciTech Connect

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 H{sub 2} drop, and bulk liquid {sup 4}He. 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 {sup 4}He.

Sakkos, K.; Casulleras, J.; Boronat, J. [Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona (Spain)

2009-05-28

67

A Hybrid Monte Carlo-Deterministic Method for Global Binary Stochastic Medium Transport Problems  

SciTech Connect

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.

Keady, K P; Brantley, P

2010-03-04

68

Strong tunneling in the electron box: a path integral Monte Carlo analysis  

Microsoft Academic Search

Strong electron tunneling effects in the single-electron box are investigated by means of a path integral Monte Carlo analysis. Our results for the effective capacitance of the box are compared to previous theoretical predictions and Monte Carlo simulations. We discuss the accuracy of our simulations and convergence of our results as a function of the Trotter number used in the

C. P. Herrero; G. Schön; A. D. Zaikin

2000-01-01

69

Quantum mechanical single molecule partition function from path integral Monte Carlo simulations  

Microsoft Academic Search

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

Shaji Chempath; Cristian Predescu; Alexis T. Bell

2006-01-01

70

Path Integral Monte Carlo finite-temperature electronic structure of quantum dots  

Microsoft Academic Search

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

Markku Leino; Tapio T. Rantala

2003-01-01

71

Gibbs-ensemble path-integral Monte Carlo simulations of a mixed quantum-classical fluid  

Microsoft Academic Search

We study a model fluid with classical translational degrees of freedom and internal quantum states in two spatial dimensions. The path-integral Monte Carlo and the Gibbs-ensemble Monte Carlo techniques are combined to investigate the liquid-gas coexistence region in this mixed quantum-classical system. A comparison with the phase diagram obtained in the canonical ensemble is also presented.

F. Schneider; D. Marx; P. Nielaba

1995-01-01

72

Hybrid two-dimensional Monte-Carlo electron transport in self-consistent electromagnetic fields  

SciTech Connect

The physics and numerics of the hybrid electron transport code ANTHEM are described. The need for the hybrid modeling of laser generated electron transport is outlined, and a general overview of the hybrid implementation in ANTHEM is provided. ANTHEM treats the background ions and electrons in a laser target as coupled fluid components moving relative to a fixed Eulerian mesh. The laser converts cold electrons to an additional hot electron component which evolves on the mesh as either a third coupled fluid or as a set of Monte Carlo PIC particles. The fluids and particles move in two-dimensions through electric and magnetic fields calculated via the Implicit Moment method. The hot electrons are coupled to the background thermal electrons by Coulomb drag, and both the hot and cold electrons undergo Rutherford scattering against the ion background. Subtleties of the implicit E- and B-field solutions, the coupled hydrodynamics, and large time step Monte Carlo particle scattering are discussed. Sample applications are presented.

Mason, R.J.; Cranfill, C.W.

1985-01-01

73

Hybrid Parallel Programming Models for AMR Neutron Monte-Carlo Transport  

NASA Astrophysics Data System (ADS)

This paper deals with High Performance Computing (HPC) applied to neutron transport theory on complex geometries, thanks to both an Adaptive Mesh Refinement (AMR) algorithm and a Monte-Carlo (MC) solver. Several Parallelism models are presented and analyzed in this context, among them shared memory and distributed memory ones such as Domain Replication and Domain Decomposition, together with Hybrid strategies. The study is illustrated by weak and strong scalability tests on complex benchmarks on several thousands of cores thanks to the petaflopic supercomputer Tera100.

Dureau, David; Poëtte, Gaël

2014-06-01

74

Higher order and infinite Trotter-number extrapolations in path integral Monte Carlo  

Microsoft Academic Search

Improvements beyond the primitive approximation in the path integral Monte Carlo method are explored both in a model problem and in real systems. Two different strategies are studied: The Richardson extrapolation on top of the path integral Monte Carlo data and the Takahashi-Imada action. The Richardson extrapolation, mainly combined with the primitive action, always reduces the number-of-beads dependence, helps in

L. Brualla; K. Sakkos; J. Boronat; J. Casulleras

2004-01-01

75

Worm algorithm and diagrammatic Monte Carlo: A new approach to continuous-space path integral Monte Carlo simulations  

Microsoft Academic Search

A detailed description is provided of a new worm algorithm, enabling the accurate computation of thermodynamic properties of quantum many-body systems in continuous space, at finite temperature. The algorithm is formulated within the general path integral Monte Carlo (PIMC) scheme, but also allows one to perform quantum simulations in the grand canonical ensemble, as well as to compute off-diagonal imaginary-time

M. Boninsegni; N. V. Prokof'Ev; B. V. Svistunov

2006-01-01

76

Hybrid integration process for the development of multisensor chips  

NASA Astrophysics Data System (ADS)

A novel hybrid integration process had been developed for the integration of single crystal pyroelectric detector with readout IC based on a thinning and anisotropic conduction tape bonding technique. We report our recent progress in applying the hybrid integration process for the fabrication of a multisensor chip with thermal and sound detectors integrated. The sound detector in the multisensor chip is based on thinned single crystal quartz, while the thermal detector in the chip is making use of thinned PLZT ceramic wafer. A membrane transfer process (MTP) was applied for the thinning and integration of the single crystal and ceramic wafers.

Jin, Na; Liu, Weiguo

77

Power electronics system integration for electric and hybrid vehicles  

Microsoft Academic Search

The paper gives an overview of the basic requirements, concepts, and trends regarding a system integration of power electronics in hybrid (HEV) and electric vehicles (EV). A site-of-action system integration of the various power electronics subsystems minimizes costs and construction space requirements. New technologies that foster a system integration of power electronics and a merging with the mechanical environment are

Martin März; Andreas Schletz; Bernd Eckardt; Sven Egelkraut; Hubert Rauh

2010-01-01

78

A Hybrid Molecular Dynamics - Kinetic Monte Carlo Approach for the Simulation of the Growth of Soot Precursors  

SciTech Connect

A new code, named Hybrid Molecular Dynamics--Kinetic Monte Carlo (Hybrid MD/KMC), has been developed and employed to analyze possible growth pathways that lead to high molecular mass compounds. The Hybrid MD-KMC code combines the strengths of two common simulation methods: Kinetic Monte Carlo, and Molecular Dynamics. This code puts the two simulation procedures on an equal footing and involves alternating between MD and KMC steps during the simulation. The strength of this approach is that it provides information on the physical as well as chemical structure of soot precursors providing at the long term potential for information on particle characteristics such as density, porosity, and other physical properties. The Kinetic Monte Carlo and Molecular Dynamics simulation are used in conjunction with high-level quantum chemical calculations.

Violi, A; Kubota, A; Truong, T N; Pitz, W; Westbrook, C K; Sarofim, A F

2001-12-17

79

Pairing Hamiltonian by a path integral Monte Carlo procedure.  

National Technical Information Service (NTIS)

A Monte Carlo approach is presented for the treatment of the pairing force in nuclear systems. This method is computationally efficient and very simple to implement. Numerical results are given and compared to an exact calculation and to the predictions o...

N. Cerf O. Martin

1992-01-01

80

Plug-in integrated/hybrid circuit  

NASA Technical Reports Server (NTRS)

Hybrid circuitry can be installed into standard round bayonet connectors, to eliminate wiring from connector to circuit. Circuits can be connected directly into either section of connector pair, eliminating need for hard wiring to that section.

Stringer, E. J.

1974-01-01

81

Optofluidic hybrid platform with integrated solid core waveguides  

NASA Astrophysics Data System (ADS)

An optofluidic hybrid platform based on hybrid liquid core ARROW waveguides has been fabricated and tested. Solid core hybrid ARROW was integrated in a self-aligned optical configuration with the ARROW optofluidic channel for an improved collection efficiency. The platform was fabricated using a modular approaches. The microfluidic system was completely realized with PDMS using a layered structure while the optical part was realized developing a hybrid silicon/PDMS solution. The performance of the system has been tested by carrying out fluorescence measurements on Cy5 water solutions, obtaining an LOD of 2.5 nM.

Testa, G.; Persichetti, G.; Sarro, P. M.; Bernini, R.

2014-03-01

82

A hybrid integrity solution for precision landing and guidance  

Microsoft Academic Search

A design was developed for a hybrid integrity solution for precision approach and landing in a GPS jamming environment. The integrity solution described in this paper leverages the capabilities of next generation digital spatial processing and ultra-tightly-coupled (UTC) GPS\\/inertial integrated military user equipment (UE). A design is also included for a spatial environment integrity monitor, for a GPS\\/inertial receiver autonomous

Kenn L. Gold; Alison K. Brown

2004-01-01

83

Path integral Monte Carlo simulations: Study of the efficiency of energy estimators  

Microsoft Academic Search

This article presents a study of the relative efficiency of two commonly used energy estimators for path integral Monte Carlo (MC) simulations; the Barker estimator and the virial estimator. Two different path integral MC algorithms are considered; the simple algorithm augmented with whole chain moves and the normal-mode algorithm. The behavior of the two estimators is analyzed in some model

Pedro Alexandrino Fernandes; Alfredo Palace Carvalho; J. P. Prates Ramalho

1995-01-01

84

Exploiting symmetries for exponential error reduction in path integral Monte Carlo  

Microsoft Academic Search

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

Michele Della Morte; Leonardo Giusti

2007-01-01

85

Exploiting symmetries for exponential error reduction in path integral Monte Carlo  

Microsoft Academic Search

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

Michele Della Morte; Leonardo Giusti

2009-01-01

86

Particle exchange in the Fourier path-integral Monte Carlo technique  

Microsoft Academic Search

A formalism which incorporates the effects of particle exchange in the Fourier path integral Monte Carlo framework is developed. Expressions for thermal averages of static quantities as well as the kinetic and total energy for identical-particle systems are derived. For bosons, the procedure for evaluating thermal averages is analogous to that in the discretized path integral approach. For fermion systems,

Charusita Chakravarty

1993-01-01

87

Fixed-Phase Path Integral Monte Carlo Simulations in Quantum Dots in Magnetic Fields  

Microsoft Academic Search

We have developed a fixed-phase approximation for path integral Monte Carlo (PIMC) simulations. With the fixed phase approximation, the difficulties created by phases in path integrals for magnetic systems are managed in a practical way. We first demonstrate the method on electrons in a 2-D parabolic dot in a magnetic field. The PIMC method allows us to extend the simulation

Daejin Shin; John Shumway

2005-01-01

88

Path-integral Monte Carlo simulation of the second layer of 4He adsorbed on graphite  

Microsoft Academic Search

We have developed a path-integral Monte Carlo method for simulating helium films and apply it to the second layer of helium adsorbed on graphite. We use helium-helium and helium-graphite interactions that are found from potentials which realistically describe the interatomic interactions. The Monte Carlo sampling is over both particle positions and permutations of particle labels. From the particle configurations and

Marlon Pierce; Efstratios Manousakis

1999-01-01

89

Path Integral Monte Carlo Calculations of Symmetry-Breaking in Structural Phase Transitions  

Microsoft Academic Search

This paper summarizes recent developments in theoretical Monte Carlo investigations of crystallographic point- and space-group symmetries in solids and of symmetry-breaking in the liquid-solid phase transition. The formal and numerical path integral Monte Carlo treatment of crystallographic symmetries and symmetry-breaking in the one- and two-body densities is outlined and the relation to experiment and to other theories is described.

K. A. Gernoth

2001-01-01

90

Path integral Monte Carlo study of SF6-doped helium clusters  

Microsoft Academic Search

The path-integral Monte Carlo technique is applied to study the SF6He39 cluster at low temperatures. The method employs as input only pair potentials, the number of atoms, and the temperature, and is thus independent of the trial function bias which can affect calculation of structural quantities in variational and diffusion Monte Carlo. We thereby obtain an unambiguous answer to the

Yongkyung Kwon; David M. Ceperley; K. Birgitta Whaley

1996-01-01

91

Thermodynamic properties of small rare gas clusters by path integral Monte Carlo simulations: a preliminary study  

Microsoft Academic Search

A strategy for reducing the risk of non-ergodic simulations in Monte Carlo calculations of the thermodynamic properties of clusters is discussed with the support of some examples. The results obtained attest the significance of the approach for the low-temperature regime, as non-ergodic sampling of potential energy surfaces is a particularly insidious occurrence. Fourier path integral Monte Carlo techniques for taking

C. Parletta; C. Guidotti; G. P. Arrighini

2004-01-01

92

Path integral Monte Carlo simulations of nanowires and quantum point contacts  

Microsoft Academic Search

We study quantum wires and point contacts with a fixed-node path integral Monte Carlo technique. The fixed-node technique uses a variational principle to map fermionic problems into effective bosonic problems, which are then evaluated with standard quantum Monte Carlo techniques. While fixed-node is an approximation, it has the useful properties of being variational and being able to recover the exact

J. Shumway; M. J. Gilbert

2006-01-01

93

Monte Carlo Simulations of Globular Cluster Evolution. IV. Direct Integration of Strong Interactions  

Microsoft Academic Search

We study the dynamical evolution of globular clusters containing populations\\u000aof primordial binaries, using our newly updated Monte Carlo cluster evolution\\u000acode with the inclusion of direct integration of binary scattering\\u000ainteractions. We describe the modifications we have made to the code, as well\\u000aas improvements we have made to the core Monte Carlo method. We present several\\u000atest calculations

John M. Fregeau; Frederic A. Rasio

2006-01-01

94

The Acceptance Probability of the Hybrid Monte Carlo Method in High-Dimensional Problems  

NASA Astrophysics Data System (ADS)

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 = l×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 l increases, against the cost related to the average number of proposals required to obtain acceptance, which increases as l increases.

Beskos, A.; Pillai, N. S.; Roberts, G. O.; Sanz-Serna, J. M.; Stuart, A. M.

2010-09-01

95

QYMSYM: A GPU-accelerated hybrid symplectic integrator  

NASA Astrophysics Data System (ADS)

QYMSYM is a GPU accelerated 2nd order hybrid symplectic integrator that identifies close approaches between particles and switches from symplectic to Hermite algorithms for particles that require higher resolution integrations. This is a parallel code running with CUDA on a video card that puts the many processors on board to work while taking advantage of fast shared memory.

Moore, Alexander; Quillen, Alice C.

2012-10-01

96

HRMC: Hybrid Reverse Monte Carlo method with silicon and carbon potentials  

NASA Astrophysics Data System (ADS)

Fortran 77 code is presented for a hybrid method of the Metropolis Monte Carlo (MMC) and Reverse Monte Carlo (RMC) for the simulation of amorphous silicon and carbon structures. In additional to the usual constraints of the pair correlation functions and average coordination, the code also incorporates an optional energy constraint. This energy constraint is in the form of either the Environment Dependent Interatomic Potential (applicable to silicon and carbon) and the original and modified Stillinger-Weber potentials (applicable to silicon). The code also allows porous systems to be modeled via a constraint on porosity and internal surface area using a novel restriction on the available simulation volume. Program summaryProgram title: HRMC version 1.0 Catalogue identifier: AEAO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAO_v1_0.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.: 200 894 No. of bytes in distributed program, including test data, etc.: 907 557 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 Nature of problem: Atomic modeling using empirical potentials and experimental data Solution method: Monte Carlo 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.

Opletal, G.; Petersen, T. C.; O'Malley, B.; Snook, I. K.; McCulloch, D. G.; Yarovsky, I.

2008-05-01

97

A Deterministic-Monte Carlo Hybrid Method for Time-Dependent Neutron Transport Problems  

SciTech Connect

A new deterministic-Monte Carlo hybrid solution technique is derived for the time-dependent transport equation. This new approach is based on dividing the time domain into a number of coarse intervals and expanding the transport solution in a series of polynomials within each interval. The solutions within each interval can be represented in terms of arbitrary source terms by using precomputed response functions. In the current work, the time-dependent response function computations are performed using the Monte Carlo method, while the global time-step march is performed deterministically. This work extends previous work by coupling the time-dependent expansions to space- and angle-dependent expansions to fully characterize the 1D transport response/solution. More generally, this approach represents and incremental extension of the steady-state coarse-mesh transport method that is based on global-local decompositions of large neutron transport problems. An example of a homogeneous slab is discussed as an example of the new developments.

Justin Pounders; Farzad Rahnema

2001-10-01

98

Extrapolated High-Order Propagators for Path Integral Monte Carlo Simulations  

Microsoft Academic Search

We present a new class of high-order imaginary time propagators for\\u000apath-integral Monte Carlo simulations by subtracting lower order propagators.\\u000aBy requiring all terms of the extrapolated propagator be sampled uniformly, the\\u000asubtraction only affects the potential part of the path integral. The\\u000anegligible violation of positivity of the resulting path integral at small time\\u000asteps has no discernable affect

Robert E. Zillich; Johannes M. Mayrhofer; Siu A. Chin

2009-01-01

99

Improved Hybrid Monte Carlo/n-Moment Transport Equations Model for the Polar Wind  

NASA Astrophysics Data System (ADS)

In many space plasma problems (e.g. terrestrial polar wind, solar wind, etc.), the plasma gradually evolves from dense collision-dominated into rarified collisionless conditions. For decades, numerous attempts were made in order to address this type of problem using simulations based on one of two approaches. These approaches are: (1) the (fluid-like) Generalized Transport Equations, GTE, and (2) the particle-based Monte Carlo (MC) techniques. In contrast to the computationally intensive MC, the GTE approach can be considerably more efficient but its validity is questionable outside the collision-dominated region depending on the number of transport parameters considered. There have been several attempts to develop hybrid models that combine the strengths of both approaches. In particular, low-order GTE formulations were applied within the collision-dominated region, while an MC simulation was applied within the collisionless region and in the collisional-to-collisionless transition region. However, attention must be paid to assuring the consistency of the two approaches in the region where they are matched. Contrary to all previous studies, our model pays special attention to the ';matching' issue, and hence eliminates the discontinuities/inaccuracies associated with mismatching. As an example, we applied our technique to the Coulomb-Milne problem because of its relevance to the problem of space plasma flow from high- to low-density regions. We will compare the velocity distribution function and its moments (density, flow velocity, temperature, etc.) from the following models: (1) the pure MC model, (2) our hybrid model, and (3) previously published hybrid models. We will also consider a wide range of the test-to-background mass ratio.

Barakat, A. R.; Ji, J.; Schunk, R. W.

2013-12-01

100

Path-integral quantum Monte Carlo studies of lattice polarons and bipolarons  

NASA Astrophysics Data System (ADS)

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.

Kornilovitch, Pavel

2008-05-01

101

Extrapolated high-order propagators for path integral Monte Carlo simulations  

Microsoft Academic Search

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

Robert E. Zillich; Johannes M. Mayrhofer; Siu A. Chin

2010-01-01

102

Thermodynamics of hot dense H-plasmas: path integral Monte Carlo simulations and analytical approximations  

Microsoft Academic Search

This work is devoted to the thermodynamics of high-temperature dense hydrogen plasmas in the pressure region between 10-1 and 102 Mbar. In particular, we present for this region results of extensive calculations based on a recently developed path integral Monte Carlo scheme (direct PIMC). This method allows for a correct treatment of the thermodynamic properties of hot dense Coulomb systems.

V. S. Filinov; M. Bonitz; W. Ebeling; V. E. Fortov

2001-01-01

103

Simulation of excited states and the sign problem in the path integral Monte Carlo method  

Microsoft Academic Search

An approach is presented to compute properties of excited states in path integral Monte Carlo simulations of quantum systems. The approach is based on the introduction of several images of the studied system which have the total wavefunction antisymmetric over permutations of these images, and a simulation of the whole system at low enough temperature. The success of the approach

Alexander P Lyubartsev

2005-01-01

104

Efficient path-integral Monte Carlo technique for ultrasmall device applications  

Microsoft Academic Search

The ability to model equilibrium electronic properties of ultrasmall devices using a path-integral Monte Carlo (PIMC) method is demonstrated. First, a direct sampling PIMC method and its advantages over Metropolis importance sampling PIMC methods in this application are described. Then two potential structures typical of ultrasmall devices, a single and a coupled double finite square well potential, are analyzed and

L. F. Register; M. A. Stroscio; M. A. Littlejohn

1989-01-01

105

Orthorhombic phase of crystalline polyethylene: A constant pressure path-integral Monte Carlo study  

Microsoft Academic Search

In this paper we present a path-integral Monte Carlo (PIMC) simulation of the orthorhombic phase of crystalline polyethylene, using an explicit atom force field with unconstrained bond lengths and angles. This work represents a quantum extension of our recent classical simulation [R. Martonák et al., J. Chem. Phys. 106, 8918 (1997)]. It is aimed both at exploring the applicability of

R. Martonák; W. Paul; K. Binder

1998-01-01

106

Quantum atomic dynamics in amorphous silicon; a path-integral Monte Carlo simulation  

Microsoft Academic Search

The quantum dynamics of atoms in amorphous silicon has been addressed by using path-integral Monte Carlo simulations. Structural results (radial distribution functions) found from these simulations agree well with experimental data. We study the quantum delocalization of the silicon atoms around their equilibrium positions. This delocalization is larger for coordination defects (fivefold-coordinated Si atoms). Correlations in the atomic displacements are

Carlos P. Herrero

2000-01-01

107

Path-integral Monte Carlo study of low-temperature 4He clusters  

Microsoft Academic Search

Path-integral Monte Carlo calculations have been used to study 4He clusters at low temperatures. We develop a fluctuation formula for the superfluid fraction in terms of a projected area swept out by a path. Manifestations of superfluid behavior are shown to exist in a cluster of 64 atoms and a remnant of the lambda transition persists in a cluster of

Philippe Sindzingre; Michael L. Klein; David M. Ceperley

1989-01-01

108

Path-integral Monte Carlo simulations without the sign problem: Multilevel blocking approach for effective actions  

Microsoft Academic Search

The multilevel blocking algorithm recently proposed as a possible solution to the sign problem in path-integral Monte Carlo simulations has been extended to systems with long-ranged interactions along the Trotter direction. As an application, results for the real-time quantum dynamics of the spin-boson model are presented.

R. Egger; L. Mühlbacher; C. H. Mak

2000-01-01

109

Formally exact path integral Monte Carlo calculations using approximate projection operators  

Microsoft Academic Search

A class of approximate projection operators is used to reduce the variance in path integral Monte Carlo calculations in a formally exact manner. Paths are classified according to the projection operators, allowing the identification of paths whose contribution to the variance is negligible. The approach is applied to two canonical systems: Two like-spin electrons in a three dimensional harmonic well

Randall W. Hall

1992-01-01

110

Equation of state of the hydrogen plasma by path integral Monte Carlo simulation  

Microsoft Academic Search

The equation of state of hydrogen plasma is calculated by the restricted path integral Monte Carlo method. We have investigated the plasma from the classical weak coupling regime to the quantum strongly coupled regime. Good agreement is found with the existing theories for low electronic degeneracy. Inception of molecular formation is observed at low densities and temperatures.

C. Pierleoni; D. M. Ceperley; B. Bernu; W. R. Magro

1994-01-01

111

Thermodynamic properties of cSi derived by quantum path-integral Monte Carlo simulations  

Microsoft Academic Search

Feynman path-integral Monte Carlo simulations of crystalline silicon, using the empirical potential of Stillinger and Weber, have been performed in the isothermal-isobaric ensemble. Several thermodynamic properties have been evaluated as a function of pressure and temperature. The calculated lattice parameter, heat capacity, thermal expansion coefficient, and bulk modulus show an overall agreement with the experimental data. However, the negative thermal

José C. Noya; Carlos P. Herrero; Rafael Ramírez

1996-01-01

112

Phase transitions and quantum effects in pore condensates: A path integral Monte Carlo study  

Microsoft Academic Search

Lennard-Jones condensates in cylindrical pores are studied by path integral Monte Carlo simulations with particular emphasis on phase transitions and quantum effects. The pore diameter effect and the influence of the interaction strength between the cylinder wall and the adsorbate particles on the structures and the location of the phase boundaries is studied and the quantum effect on the phase

J. Hoffmann; P. Nielaba

2003-01-01

113

Parallel Fourier Path-Integral Monte Carlo calculations of absolute free energies and chemical equilibria  

Microsoft Academic Search

We present a parallel implementation of the Fourier Path Integral Monte Carlo method for calculating the absolute free energies of many-body systems. The implementation adopts the message-passing paradigm for parallelization, with the use of the Message Passing Interface (MPI) libraries. A portable computer program, written using Fortran 90, has been developed and tested on a variety of platforms such as

Jay Srinivasan; Yuri L. Volobuev; Steven L. Mielke; Donald G. Truhlar

2000-01-01

114

Path Integral Monte Carlo Calculation of the Momentum Distribution of the Homogeneous Electron Gas at Finite Temperature  

Microsoft Academic Search

Path integral Monte Carlo (PIMC) simulations are used to calculate the momentum distribution of the homogeneous electron gas at finite temperature. This is done by calculating the off-diagonal elements of the real-space density matrix, represented in PIMC by open paths. It is demonstrated how the restricted path integral Monte Carlo methods can be extended in order to deal with open

B. Militzer; E. L. Pollock; D. M. Ceperley

2003-01-01

115

A path integral Monte Carlo study of quantum solutes in liquid ammonia and ammonia clusters  

Microsoft Academic Search

The path integral Monte Carlo method is applied to some solvation problems involving quantum solutes. Thermodynamics quantities like partial molar volume and entropy change associated with the electron solvaton process are calculate. The ionization of alkali atoms in liquid ammonia and the electron attachment to ammonia clusters are investigated.\\u000aPath integral MC simulations at constant pressure lead to an expansion

Massimo Marchi

1988-01-01

116

Path integral Monte Carlo simulation of the low-density hydrogen plasma  

Microsoft Academic Search

Restricted path integral Monte Carlo simulations are used to calculate the equilibrium properties of hydrogen in the density and temperature range of 9.83×10-4<=rho<=0.153 g cm-3 and 5000<=T<=250 000 K. We test the accuracy of the pair density matrix and analyze the dependence on the system size, on the time step of the path integral, and on the type of nodal

B. Militzer; D. M. Ceperley

2001-01-01

117

Elastic constants of hcp 4He: Path-integral Monte Carlo results versus experiment  

Microsoft Academic Search

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

Luis Aldemar Peña Ardila; Silvio A. Vitiello; Maurice de Koning

2011-01-01

118

Total Energies of Atoms from Path Integral Monte Carlo Simulations  

Microsoft Academic Search

Several ab initio methods exist for calculating energies of atoms, molecules, and solids. We are testing a new technique that uses Feynman path integrals. This new many-body method includes finite temperature and can be much more accurate than other popular techniques. We calculated the ground state energies of the first four atoms in the periodic table, H, He, Li and

Daejin Shin; John Shumway

2003-01-01

119

Hybrid integrated silicon optical bench planar lightguide circuits  

Microsoft Academic Search

As optical system architectures have matured over the past ten years, the use of silicon optical bench (SiOB) technology for cost effective packaging of opto-electronic components has migrated from relatively simple laser and photodetector submounts to sophisticated hybrid integrated optical subsystems. Lucent Technologies Bell Laboratories has been developing SiOB technology for use as an integrated packaging platform for lasers, photodetectors,

J. Gates; D. Muehlner; M. Cappuzzo; M. Fishteyn; L. Gomez; G. Henein; E. Laskowski; I. Ryazansky; J. Shmulovich; D. Syvertsen; A. White

1998-01-01

120

Design and optimisation of integrated hybrid surface plasmon biosensor  

NASA Astrophysics Data System (ADS)

In this paper we present a novel idea for an integrated surface plasmon biosensor. The proposed hybrid sensor aims to couple the high sensitivity of the well known Kretchmann prism excitation design with the more robust integrated waveguide design. The sensor is modelled and simulated using a 2D Finite Element Method (FEM) in order to establish the devices sensitivity, resolution and signal-to-noise-ratio.

Gorman, T.; Haxha, S.

2014-08-01

121

Hybrid Eulerian-Lagrangian Semi-Implicit Time-Integrators.  

National Technical Information Service (NTIS)

Hybrid Eulerian-Lagrangian semi-implicit time-integrators (HELSI) are presented which use the standard semi-implicit formulation as their starting point. The advantage of such an approach is that existing models which employ Eulerian semi-implicit time-in...

F. X. Giraldo

2006-01-01

122

Extrapolated high-order propagators for path integral Monte Carlo simulations.  

PubMed

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 (4)He, which is representative of a dense, and strongly interacting, quantum many-body system. PMID:20113015

Zillich, Robert E; Mayrhofer, Johannes M; Chin, Siu A

2010-01-28

123

Mixed oxidizer hybrid propulsion system optimization under uncertainty using applied response surface methodology and Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

The analysis documented herein provides an integrated approach for the conduct of optimization under uncertainty (OUU) using Monte Carlo Simulation (MCS) techniques coupled with response surface-based methods for characterization of mixture-dependent variables. This novel methodology provides an innovative means of conducting optimization studies under uncertainty in propulsion system design. Analytic inputs are based upon empirical regression rate information obtained from design of experiments (DOE) mixture studies utilizing a mixed oxidizer hybrid rocket concept. Hybrid fuel regression rate was selected as the target response variable for optimization under uncertainty, with maximization of regression rate chosen as the driving objective. Characteristic operational conditions and propellant mixture compositions from experimental efforts conducted during previous foundational work were combined with elemental uncertainty estimates as input variables. Response surfaces for mixture-dependent variables and their associated uncertainty levels were developed using quadratic response equations incorporating single and two-factor interactions. These analysis inputs, response surface equations and associated uncertainty contributions were applied to a probabilistic MCS to develop dispersed regression rates as a function of operational and mixture input conditions within design space. Illustrative case scenarios were developed and assessed using this analytic approach including fully and partially constrained operational condition sets over all of design mixture space. In addition, optimization sets were performed across an operationally representative region in operational space and across all investigated mixture combinations. These scenarios were selected as representative examples relevant to propulsion system optimization, particularly for hybrid and solid rocket platforms. Ternary diagrams, including contour and surface plots, were developed and utilized to aid in visualization. The concept of Expanded-Durov diagrams was also adopted and adapted to this study to aid in visualization of uncertainty bounds. Regions of maximum regression rate and associated uncertainties were determined for each set of case scenarios. Application of response surface methodology coupled with probabilistic-based MCS allowed for flexible and comprehensive interrogation of mixture and operating design space during optimization cases. Analyses were also conducted to assess sensitivity of uncertainty to variations in key elemental uncertainty estimates. The methodology developed during this research provides an innovative optimization tool for future propulsion design efforts.

Whitehead, James Joshua

124

Thermodynamics of coupled protein adsorption and stability using hybrid monte carlo simulations.  

PubMed

A better understanding of changes in protein stability upon adsorption can improve the design of protein separation processes. In this study, we examine the coupling of the folding and the adsorption of a model protein, the B1 domain of streptococcal protein G, as a function of surface attraction using a hybrid Monte Carlo (HMC) approach with temperature replica exchange and umbrella sampling. In our HMC implementation, we are able to use a molecular dynamics (MD) time step that is an order of magnitude larger than in a traditional MD simulation protocol and observe a factor of 2 enhancement in the folding and unfolding rate. To demonstrate the convergence of our systems, we measure the travel of our order parameter the fraction of native contacts between folded and unfolded states throughout the length of our simulations. Thermodynamic quantities are extracted with minimum statistical variance using multistate reweighting between simulations at different temperatures and harmonic distance restraints from the surface. The resultant free energies, enthalpies, and entropies of the coupled unfolding and absorption processes are in qualitative agreement with previous experimental and computational observations, including entropic stabilization of the adsorbed, folded state relative to the bulk on surfaces with low attraction. PMID:24716898

Zhong, Ellen D; Shirts, Michael R

2014-05-01

125

Comparison of hybrid and pure Monte Carlo shower generators on an event by event basis  

NASA Astrophysics Data System (ADS)

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 they are extremely accurate, SENECA is able to utilize the advantages in speed from the cascade equations yet still produce complete, three dimensional particle distributions at ground level. We present a comparison, on an event by event basis, of SENECA and CORSIKA, a well trusted MC simulation. 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 averages over many showers. Our study shows that for showers produced in this manner, SENECA agrees with CORSIKA to a very high accuracy as to densities, energies, and timing information for individual species of ground-level particles from both iron and proton primaries with energies between 1EeV and 100EeV. 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 40 EeV proton simulated with 10-6 thinning, SENECA is 10 times faster than CORSIKA.

Allen, J.; Drescher, H.-J.; Farrar, G.

126

HRMC_2.1: Hybrid Reverse Monte Carlo method with silicon, carbon, germanium and silicon carbide potentials  

NASA Astrophysics Data System (ADS)

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. In this version 2.1 update, an empirical potential for silicon-carbide has been added to the code along with an experimentally motivated constraint on the bond type fraction applicable to systems containing multiple elements.

Opletal, G.; Petersen, T. C.; Russo, S. P.

2014-06-01

127

Integrated Hybrid-Simulation of Electric Power and Communications Systems  

SciTech Connect

The modern power grid is strongly integrated with its communication network. While a power system primarily consists of elements that are modeled by continuous equations, a communication system has discrete event dynamics. We model the integrated operation of these two systems with a hybrid modeling and simulation technique. Systematically combining continuous and discrete event system models is necessary for correctly simulating critical system behaviors. This paper discusses an approach based on the discrete event system specification (DEVS) that characterizes the interaction of the two systems formally to preserve simulation correctness. We demonstrate the implementation of our integrated hybrid simulation technique with detailed generator and network models in a wide-area cooperative automatic load-control scenario.

Nutaro, James J [ORNL; Kuruganti, Phani Teja [ORNL; Miller, Laurie E [ORNL; Mullen, Sara [ORNL; Shankar, Mallikarjun [ORNL

2007-01-01

128

All-electron path integral Monte Carlo simulations of warm dense matter: application to water and carbon plasmas.  

PubMed

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)×10(5) K, and both methods together form a coherent equation of state over a density-temperature range of 3-12 g/cm(3) and 10(4)-10(9) K. PMID:22540485

Driver, K P; Militzer, B

2012-03-16

129

Calculation of exchange frequencies in bcc 3He with the path-integral Monte Carlo method  

Microsoft Academic Search

The exchange frequency in crystal 3He is calculated from first principles with a combination of path-integral Monte Carlo method and a method used in classical statistical mechanics to determine free-energy differences. The frequency of nearest-neighbor exchange at melting density is 0.46 mK, that of triple exchange is 0.19 mK, and that of four-particle planar exchange is 0.27 mK. These exchange

D. M. Ceperley; G. Jacucci

1987-01-01

130

Path-integral Monte Carlo study of crystalline Lennard-Jones systems  

Microsoft Academic Search

The capability of the path-integral Monte Carlo (PIMC) method to describe thermodynamic and structural properties of solids at low temperatures is studied in detail, considering the noble-gas crystals as examples. In order to reduce the systematic limitations due to finite Trotter number and finite particle number we propose a combined Trotter and finite-size scaling. As a special application of the

M. H. Müser; P. Nielaba; K. Binder

1995-01-01

131

Path-integral Monte Carlo simulation of helium at negative pressures  

Microsoft Academic Search

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

Gregory H. Bauer; David M. Ceperley; Nigel Goldenfeld

2000-01-01

132

Orientational order in dense molecular hydrogen: A first-principles path-integral Monte Carlo calculation  

Microsoft Academic Search

A quantum-mechanical simulation of orientational order in solid molecular hydrogen is presented, based on path-integral Monte Carlo calculations. The effective potential between nearest-neighbor hydrogen molecules is derived from first-principles total energy calculations, taking full account of the symmetries of the Hamiltonian within a hexagonal close-packed arrangement of the molecule centers. A first-order orientational order transition is found by studying short-

Efthimios Kaxiras; Zhian Guo

1994-01-01

133

Path-integral Monte Carlo simulation of hydrogen in crystalline silicon  

Microsoft Academic Search

Isolated hydrogen and deuterium in crystalline silicon have been studied by the path-integral Monte Carlo method. Interactions between Si atoms were modeled by the Stillinger-Weber potential, and the Si-H interaction was parametrized by following the results of earlier pseudopotential-density-functional calculations for this system. Finite-temperature properties of these point defects are analyzed in the range from 50 to 600 K. Hydrogen

Carlos P. Herrero; Rafael Ramírez

1995-01-01

134

Worm Algorithm for Continuous-Space Path Integral Monte Carlo Simulations  

SciTech Connect

We present a new approach to path integral Monte Carlo (PIMC) simulations based on the worm algorithm, originally developed for lattice models and extended here to continuous-space many-body systems. The scheme allows for efficient computation of thermodynamic properties, including winding numbers and off-diagonal correlations, for systems of much greater size than that accessible to conventional PIMC simulations. As an illustrative application of the method, we simulate the superfluid transition of {sup 4}He in two dimensions.

Boninsegni, Massimo [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Prokof'ev, Nikolay [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Russian Research Center 'Kurchatov Institute', 123182 Moscow (Russian Federation); Department of Physics, Cornell University, Ithaca, New York 14850 (United States); Svistunov, Boris [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Russian Research Center 'Kurchatov Institute', 123182 Moscow (Russian Federation)

2006-02-24

135

Solid helium at high pressure: a path-integral Monte Carlo simulation  

Microsoft Academic Search

Solid helium (3He and 4He) in the hcp and fcc phases has been studied by path-integral Monte Carlo. Simulations were carried out in the isothermal-isobaric (NPT) ensemble at pressures up to 52 GPa. This allows one to study the temperature and pressure dependences of isotopic effects on the crystal volume and vibrational energy in a wide parameter range. The obtained

Carlos P. Herrero

2006-01-01

136

Rotational ordering in solid deuterium and hydrogen: A path integral Monte Carlo study  

Microsoft Academic Search

The path-integral Monte Carlo method with a constant-pressure ensemble is used to study both translational and orientational transitions in the phase diagram of Dâ and Hâ up to megabar pressures. With an intermolecular interaction potential determined to agree with the experimental equation of state, a rotational order-disorder phase transition is observed. The phase line for this transition is in quantitative

T. Cui; E. Cheng; B. J. Alder; K. B. Whaley

1997-01-01

137

Path-integral Monte Carlo calculation of the kinetic energy of condensed lithium  

Microsoft Academic Search

We report path-integral Monte Carlo calculations of the kinetic energy of condensed lithium for several temperatures in both the solid and liquid phases. The excess kinetic energy of lithium decreases from about 10.4% of the classical value at 300 K to 3.2% at 520 K indicating a very slow decay with temperature. A Wigner-Kirkwood perturbation treatment of quantum effects to

Claudia Filippi; David M. Ceperley

1998-01-01

138

Superfluidity and BEC in optical lattices and porous media: a path integral Monte Carlo study  

Microsoft Academic Search

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. The periodic lattice consists of a cubic cell containing a potential well that is replicated along 1D using periodic boundary conditions. The aim is to describe bosons in a 1D optical lattice or helium confined in a

Ali A. Shams; H. R. Glyde

139

Vortices and 2D Bosons: A Path-Integral Monte Carlo Study  

Microsoft Academic Search

The vortex system in a high- Tc superconductor has been studied numerically using the mapping to 2D bosons and the path-integral Monte Carlo method. We find a single first-order transition from an Abrikosov lattice to an entangled vortex liquid. The transition is characterized by an entropy jump DeltaS~0.4kB per vortex and layer (parameters for YBa2Cu3O7) and a Lindemann number cL~0.25.

Henrik Nordborg; Gianni Blatter

1997-01-01

140

Isotopic shift of helium melting pressure: Path integral Monte Carlo study  

Microsoft Academic Search

We compute by a path integral Monte Carlo calculation the isotropic shift of helium melting pressure in the temperature range (T>100 K) where a discrepancy between theory and experiment has been recently reported. We use a realistic Aziz pair potential together with Bruch-McGee three-body forces for the interaction. The isotopic shift predicted in this work is in agreement with experiment;

M. Boninsegni; C. Pierleoni; D. M. Ceperley

1994-01-01

141

Structural and thermodynamic properties of diamond: A path-integral Monte Carlo study  

Microsoft Academic Search

Path-integral Monte Carlo simulations in the isothermal-isobaric ensemble have been carried out to study structural and thermodynamic properties of diamond, as a function of temperature and hydrostatic pressure. Atomic nuclei were treated as quantum particles interacting through a Tersoff-type potential. The obtained lattice parameter, heat capacity, thermal expansion coefficient, and bulk modulus show an overall agreement with the experimental data.

Carlos P. Herrero; Rafael Ramírez

2001-01-01

142

Solid helium at high pressure: a path-integral Monte Carlo simulation  

Microsoft Academic Search

Solid helium (3He and 4He) in the hcp and fcc phases has been studied by the path-integral Monte Carlo technique. Simulations were carried out in the isothermal–isobaric (NPT) ensemble at pressures up to 52GPa. This allows one to study the temperature and pressure dependences of isotopic effects on the crystal volume and vibrational energy in a wide parameter range. The

Carlos P. Herrero

2006-01-01

143

Path-integral Monte Carlo study of phonons in the bcc phase of 4He  

Microsoft Academic Search

Using path-integral Monte Carlo and the maximum entropy method, we calculate the dynamic structure factor of solid He4 in the bcc phase at a finite temperature of T=1.6K and a molar volume of 21cm3 . Both the single-phonon contribution to the dynamic structure factor and the total dynamic structure factor are evaluated. From the dynamic structure factor, we obtain the

V. Sorkin; E. Polturak; Joan Adler

2005-01-01

144

Rare-gas solids under pressure: A path-integral Monte Carlo simulation  

Microsoft Academic Search

Rare-gas solids (Ne, Ar, Kr, and Xe) under hydrostatic pressure up to 30 kbar\\u000ahave been studied by path-integral Monte Carlo simulations in the\\u000aisothermal-isobaric ensemble. Results of these simulations have been compared\\u000awith available experimental data and with those obtained from a quasiharmonic\\u000aapproximation (QHA). This comparison allows us to quantify the overall\\u000aanharmonicity of the lattice vibrations and

Carlos P. Herrero; Rafael Ram ´ õrez

2005-01-01

145

Path integral Monte Carlo simulations of the melting of molecular hydrogen surfaces  

Microsoft Academic Search

We have used Path Integral Monte Carlo to study the surface melting of molecular hydrogen. Density profiles perpendicular and parallel to the bare H2 surface are computed showing the formation of a liquid adlayer at 6 K, less than half the bulk melting temperature of para-hydrogen, 13.8 K. To estimate the onset temperature and depth of H2 surface melting we

Marcus Wagner; David M. Ceperley

1996-01-01

146

A dense hydrogen plasma modeled by the path integral-Monte Carlo method  

Microsoft Academic Search

An approach to the exact description of exchange in disordered quantum systems at finite temperatures is formulated in terms\\u000a of Feynman path integrals, which eliminates rigid restrictions on the number of particles and allows numerical simulation\\u000a of the equilibrium characteristics of the electron component of a dense plasma to be performed by the Monte Carlo method.\\u000a The combinatorial weight factors

S. V. Shevkunov

2002-01-01

147

Isotope dependence of the lattice parameter of germanium from path-integral Monte Carlo simulations  

Microsoft Academic Search

The dependence of the lattice parameter upon the isotope mass for five isotopically pure Ge crystals was studied by quantum path-integral Monte Carlo simulations. The interatomic interactions in the solid were described by an empirical potential of the Stillinger-Weber type. At 50 K the isotopic effect leads to an increase of 2.3×10-4 Å in the lattice parameter of 70Ge with

José C. Noya; Carlos P. Herrero; Rafael Ramírez

1997-01-01

148

Path integral Monte Carlo and density functional molecular dynamics simulations of hot, dense helium  

Microsoft Academic Search

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

B. Militzer

2009-01-01

149

Path Integral Monte Carlo Studies of molecular para-hydrogen clusters  

Microsoft Academic Search

Using the path integral Monte Carlo method, we have extensively studied para-hydrogen clusters, (pH_2)_N, with 6<= N <= 35 as a function of temperature. Small molecular para-hydrogen clusters are predicted to be superfluid at temperatures below about 2K. In view of recent experiments, we characterize the structual and energetic properties over the temperature range T = 1 - 10K using

Kwangsik Nho; Doerte Blume

2004-01-01

150

Path integral monte carlo simulations of thin 4 He films on a H 2 surface  

Microsoft Academic Search

Atomatically thin4He films of up to three monolayers on molecular hydrogen (1,1,1) surfaces are studied at T = 0.5 K, using path integral Monte Carlo. We compute the binding energy of4He to the H2 substrate as a function of4He coverage and obtain evidence of the prewetting transition. Density profiles perpendicular to the4He-H2 interface are obtained, as well as the zero

Marcus Wagner; David M. Ceperley

1994-01-01

151

Rare-gas solids under pressure: A path-integral Monte Carlo simulation  

Microsoft Academic Search

Rare-gas solids (Ne, Ar, Kr, and Xe) under hydrostatic pressure up to 30kbar have been studied by path-integral Monte Carlo (PIMC) simulations in the isothermal-isobaric ensemble. Results of these simulations have been compared with available experimental data and with those obtained from a quasiharmonic approximation (QHA). This comparison allows us to quantify the overall anharmonicity of the lattice vibrations and

Carlos P. Herrero; Rafael Ramírez

2005-01-01

152

Integrating kinetic models for Simulating tumor growth in Monte Carlo Simulation of ECT systems  

Microsoft Academic Search

We have developed an integrated framework for linking tumor growth models directly into a Monte Carlo simulation algorithm for positron emission tomography and single-photon emission computed tomography systems. Tumors are approximated either by analytically defined five-dimensional (x,y,z,tgeometry,tactivity) compartments or by compound cellular lattice inserts. Both representation models can be placed into arbitrarily complex tomographic or mathematical phantoms. Various models for

Joerg Peter; Wolfhard Semmler

2004-01-01

153

Parallel Quasi-Monte Carlo Integration Using (t, s)Sequences  

Microsoft Academic Search

Currently, the most effective constructions of low-discrepancy point sets and sequences are based on the theory of (t, m, s)-nets and (t, s)-sequences. In this work we discuss parallelization techniques for quasi-Monte Carlo integration using (t, s)-sequences. We show that leapfrog parallelization may be very dangerous whereas block-based parallelization turns out to\\u000a be robust.

Wolfgang Ch. Schmid; Andreas Uhl

1999-01-01

154

Path integral Monte Carlo approach for weakly bound van der Waals complexes with rotations: Algorithm and benchmark calculations  

Microsoft Academic Search

A path integral Monte Carlo technique suitable for the treatment of doped helium clusters with inclusion of the rotational degrees of freedom of the dopant is introduced. The extrapolation of the results to the limit of infinite Trotter number is discussed in detail. Benchmark calculations for small weakly bound 4HeN-OCS clusters are presented. The Monte Carlo results are compared with

Nicholas Blinov; Xiaogeng Song; Pierre-Nicholas Roy

2004-01-01

155

Integration mechanism for a parallel hybrid vehicle system  

Microsoft Academic Search

The parallel hybrid-vehicle system discussed here features two mechanisms: an internal-combustion-engine energy-distribution mechanism and dual energy-integration mechanism. The former comprises a first pulley set and a second pulley set, whereby it is possible to adjust its radius ratio and change the road surface oriented output load, output speed and required load, to maintain an optimal operating state for the internal-combustion

K. David Huang; Sheng-Chung Tzeng; Tzer-Ming Jeng; Chia-Chang Chen

2005-01-01

156

Hybrid integration of optical modules for planar deflector switches  

NASA Astrophysics Data System (ADS)

Nonblocking crossconnect photonic switches based on light beam deflection require planar optical modules with hybrid integration of active deflector chips. In this work we present optical modules with two dimensional silica microlens arrays and slab waveguides fabricated on silicon substrates. The 1.55 ?m light is launched in the input microlens array, which collimates parallel beams propagating along the module. The slab waveguide vertically confines the light. The output microlenses focus the beams laterally into output fibers. Two chips are inserted in the light path after the input microlens and before the output microlens arrays. The input and output microlenses allow propagation of the light beams through modules up to 100 mm long with a beam width of less than 400 ?m. A hybrid integration process flow is developed to place the deflector chips in the light path with high alignment accuracy. The chips are flip-chip bonded to the substrate with submicron accuracy in the vertical positioning. Various contributions can lead to the chip displacements such as, for example, standoff island height variations, aligner tolerances, substrate bow, etc. Experiments are conducted to evaluate the effect of chip displacement on the insertion losses of the hybrid-integrated modules. 100-mm long optical modules with input and output chips are fabricated with less than 4 dB insertion losses. The analysis of loss contributions and possibilities for improvements are discussed.

Glebov, Alexei L.; Peters, Michael; Roman, James; Kudzuma, David; Liu, Kuo-Chuan; Lee, Michael; Yokouchi, Kishio

2004-06-01

157

Worm algorithm and diagrammatic Monte Carlo: A new approach to continuous-space path integral Monte Carlo simulations  

SciTech Connect

A detailed description is provided of a new worm algorithm, enabling the accurate computation of thermodynamic properties of quantum many-body systems in continuous space, at finite temperature. The algorithm is formulated within the general path integral Monte Carlo (PIMC) scheme, but also allows one to perform quantum simulations in the grand canonical ensemble, as well as to compute off-diagonal imaginary-time correlation functions, such as the Matsubara Green function, simultaneously with diagonal observables. Another important innovation consists of the expansion of the attractive part of the pairwise potential energy into elementary (diagrammatic) contributions, which are then statistically sampled. This affords a complete microscopic account of the long-range part of the potential energy, while keeping the computational complexity of all updates independent of the size of the simulated system. The computational scheme allows for efficient calculations of the superfluid fraction and off-diagonal correlations in space-time, for system sizes which are orders of magnitude larger than those accessible to conventional PIMC. We present illustrative results for the superfluid transition in bulk liquid {sup 4}He in two and three dimensions, as well as the calculation of the chemical potential of hcp {sup 4}He.

Boninsegni, M. [Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1 (Canada); Prokof'ev, N. V. [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); BEC-INFM, Dipartimento di Fisica, Universita di Trento, Via Sommarive 14, I-38050 Povo (Italy); Russian Research Center, Kurchatov Institute, 123182 Moscow (Russian Federation); Svistunov, B. V. [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Russian Research Center, Kurchatov Institute, 123182 Moscow (Russian Federation)

2006-09-15

158

Graphene/Si CMOS Hybrid Hall Integrated Circuits.  

PubMed

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

Huang, Le; Xu, Huilong; Zhang, Zhiyong; Chen, Chengying; Jiang, Jianhua; Ma, Xiaomeng; Chen, Bingyan; Li, Zishen; Zhong, Hua; Peng, Lian-Mao

2014-01-01

159

Graphene/Si CMOS Hybrid Hall Integrated Circuits  

PubMed Central

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.

Huang, Le; Xu, Huilong; Zhang, Zhiyong; Chen, Chengying; Jiang, Jianhua; Ma, Xiaomeng; Chen, Bingyan; Li, Zishen; Zhong, Hua; Peng, Lian-Mao

2014-01-01

160

Iterative Monte Carlo path integral with optimal grids from whole-necklace sampling.  

PubMed

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. PMID:20866124

Jadhao, Vikram; Makri, Nancy

2010-09-21

161

Hybrid method for fast Monte Carlo simulation of diffuse reflectance from a multilayered tissue model with tumor-like heterogeneities.  

PubMed

We present a hybrid method that combines a multilayered scaling method and a perturbation method to speed up the Monte Carlo simulation of diffuse reflectance from a multilayered tissue model with finite-size tumor-like heterogeneities. The proposed method consists of two steps. In the first step, a set of photon trajectory information generated from a baseline Monte Carlo simulation is utilized to scale the exit weight and exit distance of survival photons for the multilayered tissue model. In the second step, another set of photon trajectory information, including the locations of all collision events from the baseline simulation and the scaling result obtained from the first step, is employed by the perturbation Monte Carlo method to estimate diffuse reflectance from the multilayered tissue model with tumor-like heterogeneities. Our method is demonstrated to shorten simulation time by several orders of magnitude. Moreover, this hybrid method works for a larger range of probe configurations and tumor models than the scaling method or the perturbation method alone. PMID:22352630

Zhu, Caigang; Liu, Quan

2012-01-01

162

Path Integral Monte Carlo Calculation of the Momentum Distribution of the Homogeneous Electron Gas at Finite Temperature  

Microsoft Academic Search

Path integral Monte Carlo (PIMC) simulations are used to calculate the\\u000amomentum distribution of the homogeneous electron gas at finite temperature.\\u000aThis is done by calculating the off-diagonal elements of the real-space density\\u000amatrix, represented in PIMC by open paths. It is demonstrated how the\\u000arestricted path integral Monte Carlo methods can be extended in order to deal\\u000awith open

B. Militzer; E. L. Pollock; D. M. Ceperley

2003-01-01

163

Development of Integrated Motor Assist Hybrid System: Development of the 'Insight', a Personal Hybrid Coupe  

SciTech Connect

This paper presents the technical approach used to design and develop the powerplant for the Honda Insight, a new motor assist hybrid vehicle with an overall development objective of just half the fuel consumption of the current Civic over a wide range of driving conditions. Fuel consumption of 35km/L (Japanese 10-15 mode), and 3.4L/100km (98/69/EC) was realized. To achieve this, a new Integrated Motor Assist (IMA) hybrid power plant system was developed, incorporating many new technologies for packaging and integrating the motor assist system and for improving engine thermal efficiency. This was developed in combination with a new lightweight aluminum body with low aerodynamic resistance. Environmental performance goals also included the simultaneous achievement of low emissions (half the Japanese year 2000 standards, and half the EU2000 standards), high efficiency, and recyclability. Full consideration was also given to key consumer attributes, including crash safety performance, handling, and driving performance.

Kaoru Aoki; Shigetaka Kuroda; Shigemasa Kajiwara; Hiromitsu Sato; Yoshio Yamamoto

2000-06-19

164

Quantum Mechanical Single Molecule Partition Function from PathIntegral Monte Carlo Simulations  

SciTech Connect

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.

Chempath, Shaji; Bell, Alexis T.; Predescu, Cristian

2006-10-01

165

Path integrals and large deviations in stochastic hybrid systems.  

PubMed

We construct a path-integral representation of solutions to a stochastic hybrid system, consisting of one or more continuous variables evolving according to a piecewise-deterministic dynamics. The differential equations for the continuous variables are coupled to a set of discrete variables that satisfy a continuous-time Markov process, which means that the differential equations are only valid between jumps in the discrete variables. Examples of stochastic hybrid systems arise in biophysical models of stochastic ion channels, motor-driven intracellular transport, gene networks, and stochastic neural networks. We use the path-integral representation to derive a large deviation action principle for a stochastic hybrid system. Minimizing the associated action functional with respect to the set of all trajectories emanating from a metastable state (assuming that such a minimization scheme exists) then determines the most probable paths of escape. Moreover, evaluating the action functional along a most probable path generates the so-called quasipotential used in the calculation of mean first passage times. We illustrate the theory by considering the optimal paths of escape from a metastable state in a bistable neural network. PMID:24827272

Bressloff, Paul C; Newby, Jay M

2014-04-01

166

Path integrals and large deviations in stochastic hybrid systems  

NASA Astrophysics Data System (ADS)

We construct a path-integral representation of solutions to a stochastic hybrid system, consisting of one or more continuous variables evolving according to a piecewise-deterministic dynamics. The differential equations for the continuous variables are coupled to a set of discrete variables that satisfy a continuous-time Markov process, which means that the differential equations are only valid between jumps in the discrete variables. Examples of stochastic hybrid systems arise in biophysical models of stochastic ion channels, motor-driven intracellular transport, gene networks, and stochastic neural networks. We use the path-integral representation to derive a large deviation action principle for a stochastic hybrid system. Minimizing the associated action functional with respect to the set of all trajectories emanating from a metastable state (assuming that such a minimization scheme exists) then determines the most probable paths of escape. Moreover, evaluating the action functional along a most probable path generates the so-called quasipotential used in the calculation of mean first passage times. We illustrate the theory by considering the optimal paths of escape from a metastable state in a bistable neural network.

Bressloff, Paul C.; Newby, Jay M.

2014-04-01

167

Hybrid silicon free-space source with integrated beam steering  

NASA Astrophysics Data System (ADS)

Free-space beam steering using optical phase arrays are desirable as a means of implementing Light Detection and Ranging (LIDAR) and free-space communication links without the need for moving parts, thus alleviating vulnerabilities due to vibrations and inertial forces. Implementing such an approach in silicon photonic integrated circuits is particularly desirable in order to take advantage of established CMOS processing techniques while reducing both device size and packaging complexity. In this work we demonstrate a free-space diode laser together with beam steering implemented on-chip in a silicon photonic circuit. A waveguide phased array, surface gratings, a hybrid III-V/silicon laser and an array of hybrid III/V silicon amplifiers were fabricated on-chip in order to achieve a fully integrated steerable free-space optical source with no external optical inputs, thus eliminating the need for fiber coupling altogether. The chip was fabricated using a modified version of the hybrid silicon process developed at UCSB, with modifications in order to incorporate diodes within the waveguide layer as well as within the III-V gain layer. Beam steering across a 12° field of view with +/-0.3° accuracy and 1.8°x0.6° beam width was achieved, with background peaks suppressed 7 dB relative to the main lobe within the field of view for arbitrarily chosen beam directions.

Doylend, J. K.; Heck, M. J. R.; Bovington, J. T.; Peters, J. D.; Davenport, M. L.; Coldren, L. A.; Bowers, J. E.

2013-02-01

168

Hybrid and Parallel Domain-Decomposition Methods Development to Enable Monte Carlo for Reactor Analyses  

Microsoft Academic Search

This paper describes code and methods development at the Oak Ridge National Laboratory focused on enabling high-fidelity, large-scale reactor analyses with Monte Carlo (MC). Current state-of-the-art tools and methods used to perform ''real'' commercial reactor analyses have several undesirable features, the most significant of which is the non-rigorous spatial decomposition scheme. Monte Carlo methods, which allow detailed and accurate modeling

John C Wagner; Scott W Mosher; Thomas M Evans; Douglas E. Peplow; John A Turner

2010-01-01

169

Hybrid and Parallel Domain-Decomposition Methods Development to Enable Monte Carlo for Reactor Analyses  

Microsoft Academic Search

This paper describes code and methods development at the Oak Ridge National Laboratory focused on enabling high-fidelity, large-scale reactor analyses with Monte Carlo (MC). Current state-of-the-art tools and methods used to perform real commercial reactor analyses have several undesirable features, the most significant of which is the non-rigorous spatial decomposition scheme. Monte Carlo methods, which allow detailed and accurate modeling

John C Wagner; Scott W Mosher; Thomas M Evans; Douglas E. Peplow; John A Turner

2011-01-01

170

Metropolis Monte Carlo integration on the Lefschetz thimble: Application to a one-plaquette model  

NASA Astrophysics Data System (ADS)

We propose a new algorithm based on the Metropolis sampling method to perform Monte Carlo integration for path integrals in the recently proposed formulation of quantum field theories on the Lefschetz thimble. The algorithm is based on a mapping between the curved manifold defined by the Lefschetz thimble of the full action and the flat manifold associated with the corresponding quadratic action. We discuss an explicit method to calculate the residual phase due to the curvature of the Lefschetz thimble. Finally, we apply this new algorithm to a simple one-plaquette model where our results are in perfect agreement with the analytic integration. We also show that for this system the residual phase does not represent a sign problem.

Mukherjee, Abhishek; Cristoforetti, Marco; Scorzato, Luigi

2013-09-01

171

Golden Ratio Versus Pi as Random Sequence Sources for Monte Carlo Integration  

NASA Technical Reports Server (NTRS)

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.

Sen, S. K.; Agarwal, Ravi P.; Shaykhian, Gholam Ali

2007-01-01

172

Path-Integral Monte Carlo Simulations of Ideal Strength and Peierls Stress in HCP 4He  

NASA Astrophysics Data System (ADS)

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.

Josué Landinez Borda, Edgar; de Koning, Maurice

2013-03-01

173

Imaginary time path integral Monte Carlo route to rate coefficients for nonadiabatic barrier crossing  

NASA Technical Reports Server (NTRS)

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.

Wolynes, Peter G.

1987-01-01

174

Path-Integral Monte Carlo Simulation of the Warm Dense Homogeneous Electron Gas  

NASA Astrophysics Data System (ADS)

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.

Brown, Ethan W.; Clark, Bryan K.; DuBois, Jonathan L.; Ceperley, David M.

2013-04-01

175

Thermodynamic properties of c-Si derived by quantum path-integral Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

Feynman path-integral Monte Carlo simulations of crystalline silicon, using the empirical potential of Stillinger and Weber, have been performed in the isothermal-isobaric ensemble. Several thermodynamic properties have been evaluated as a function of pressure and temperature. The calculated lattice parameter, heat capacity, thermal expansion coefficient, and bulk modulus show an overall agreement with the experimental data. However, the negative thermal expansion of silicon at temperatures below 120 K is not reproduced with this model potential. The importance of anharmonicity and quantum effects on the properties derived from the Stillinger-Weber potential is addressed by comparison with the results expected in a quasiharmonic approximation and in the classical limit.

Noya, José C.; Herrero, Carlos P.; Ramírez, Rafael

1996-04-01

176

Path Integral Monte Carlo Simulations of Charged Particles in a Magnetic Field.  

NASA Astrophysics Data System (ADS)

The application of the path integral Monte Carlo (PIMC) method is discussed for the problem of charged particles in a static magnetic field. A major reason behind a lack of activity in this area has been a general pessimism regarding the statistical noise, which is expected to overwhelm the computation of thermal averages for moderately strong fields and low temperatures. Causes for the breakdown of PIMC in this regime are examined, while a modified procedure is derived, whose usefulness is illustrated via the computation of ground state properties of a system of parabolically confined non-interacting charged particles in a strong magnetic field.

Pearson, Sean

1997-03-01

177

Hybrid two-chain simulation and integral equation theory : application to polyethylene liquids.  

SciTech Connect

We present results from a hybrid simulation and integral equation approach to the calculation of polymer melt properties. The simulation consists of explicit Monte Carlo (MC) sampling of two polymer molecules, where the effect of the surrounding chains is accounted for by an HNC solvation potential. The solvation potential is determined from the Polymer Reference Interaction Site Model (PRISM) as a functional of the pair correlation function from simulation. This hybrid two-chain MC-PRISM approach was carried out on liquids of polyethylene chains of 24 and 66 CH{sub 2} units. The results are compared with MD simulation and self-consistent PRISM-PY theory under the same conditions, revealing that the two-chain calculation is close to MD, and able to overcome the defects of the PRISM-PY closure and predict more accurate structures of the liquid at both short and long range. The direct correlation function, for instance, has a tail at longer range which is consistent with MD simulation and avoids the short-range assumptions in PRISM-PY theory. As a result, the self-consistent two-chain MC-PRISM calculation predicts an isothermal compressibility closer to the MD results.

Huimin Li, David T. Wu (Colorado School of Mines Golden, CO.); Curro, John G.; McCoy, John Dwane (New Mexico Institute of Mining & Technology Socorro, NM.)

2006-02-01

178

Simulations of particle acceleration in parallel shocks: Direct comparison between Monte Carlo and one-dimensional hybrid codes  

NASA Technical Reports Server (NTRS)

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.

Ellison, Donald C.; Giacalone, J.; Burgess, D.; Schwartz, S. J.

1993-01-01

179

Improved methods for path integral Monte Carlo integration in fermionic systems  

Microsoft Academic Search

We generalize the discretized Feynman path integral expansion by replacing the path through pure states with a path through idempotent density matrices. The transformed expression converges to the ordinary path integral, but is computationally more flexible than the ordinary form. By introducing a particular choice of these idempotent density matrices, based on rotational averaging around the two-particle center of mass,

William H. Newman; Atsuo Kuki

1992-01-01

180

Hybrid integrated optic modules for real-time signal processing  

NASA Technical Reports Server (NTRS)

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.

Tsai, C. S.

1984-01-01

181

Path integral Monte Carlo calculations of helium and hydrogen–helium plasma thermodynamics and of the deuterium shock Hugoniot  

Microsoft Academic Search

In this work, we calculate the thermodynamic properties of hydrogen–helium plasmas with different mass fractions of helium by the direct path integral Monte Carlo method. To avoid unphysical approximations, we use the path integral representation of the density matrix. We pay special attention to the region of weak coupling and degeneracy and compare the results of simulation with a model

P. R. Levashov; V. S. Filinov; M. Bonitz; V. E. Fortov

2006-01-01

182

Convergence Study of the Path Integral Monte Carlo Technique for a Quantum Particle in a Supercritical Fluid  

Microsoft Academic Search

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

Terrence Reese; Bruce Miller

2008-01-01

183

Path integral Monte Carlo calculations of helium and hydrogen helium plasma thermodynamics and of the deuterium shock Hugoniot  

Microsoft Academic Search

In this work, we calculate the thermodynamic properties of hydrogen-helium plasmas with different mass fractions of helium by the direct path integral Monte Carlo method. To avoid unphysical approximations, we use the path integral representation of the density matrix. We pay special attention to the region of weak coupling and degeneracy and compare the results of simulation with a model

P. R. Levashov; V. S. Filinov; M. Bonitz; V. E. Fortov

2006-01-01

184

Quantum annealing by the path-integral Monte Carlo method: The two-dimensional random Ising model  

Microsoft Academic Search

Quantum annealing was recently found experimentally in a disordered spin-1\\/2 magnet to be more effective than its classical, thermal counterpart. We use the random two-dimensional Ising model as a test example and perform on it both classical and quantum (path-integral) Monte Carlo annealing. A systematic study of the dependence of the final residual energy on the annealing Monte Carlo time

Roman Martonák; Giuseppe E. Santoro; Erio Tosatti

2002-01-01

185

On processed splitting methods and high-order actions in path-integral Monte Carlo simulations.  

PubMed

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. PMID:20969377

Casas, Fernando

2010-10-21

186

Path integral Monte Carlo simulation of the low-density hydrogen plasma  

SciTech Connect

Restricted path integral Monte Carlo simulations are used to calculate the equilibrium properties of hydrogen in the density and temperature range of 9.83{times}10{sup {minus}4}{le}{rho}{le}0.153 gcm{sup {minus}3} and 5000{le}T{le}250000 K. We test the accuracy of the pair density matrix and analyze the dependence on the system size, on the time step of the path integral, and on the type of nodal surface. We calculate the equation of state and compare with other models for hydrogen valid in this regime. Further, we characterize the state of hydrogen and describe the changes from a plasma to an atomic and molecular liquid by analyzing the pair correlation functions and estimating the number of atoms and molecules present.

Militzer, B.; Ceperley, D. M.

2001-06-01

187

Data assimilation using a GPU accelerated path integral Monte Carlo approach  

NASA Astrophysics Data System (ADS)

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.

Quinn, John C.; Abarbanel, Henry D. I.

2011-09-01

188

hybridMANTIS: a CPU-GPU Monte Carlo method for modeling indirect x-ray detectors with columnar scintillators.  

PubMed

The computational modeling of medical imaging systems often requires obtaining a large number of simulated images with low statistical uncertainty which translates into prohibitive computing times. We describe a novel hybrid approach for Monte Carlo simulations that maximizes utilization of CPUs and GPUs in modern workstations. We apply the method to the modeling of indirect x-ray detectors using a new and improved version of the code MANTIS, an open source software tool used for the Monte Carlo simulations of indirect x-ray imagers. We first describe a GPU implementation of the physics and geometry models in fastDETECT2 (the optical transport model) and a serial CPU version of the same code. We discuss its new features like on-the-fly column geometry and columnar crosstalk in relation to the MANTIS code, and point out areas where our model provides more flexibility for the modeling of realistic columnar structures in large area detectors. Second, we modify PENELOPE (the open source software package that handles the x-ray and electron transport in MANTIS) to allow direct output of location and energy deposited during x-ray and electron interactions occurring within the scintillator. This information is then handled by optical transport routines in fastDETECT2. A load balancer dynamically allocates optical transport showers to the GPU and CPU computing cores. Our hybridMANTIS approach achieves a significant speed-up factor of 627 when compared to MANTIS and of 35 when compared to the same code running only in a CPU instead of a GPU. Using hybridMANTIS, we successfully hide hours of optical transport time by running it in parallel with the x-ray and electron transport, thus shifting the computational bottleneck from optical tox-ray transport. The new code requires much less memory than MANTIS and, asa result, allows us to efficiently simulate large area detectors. PMID:22469917

Sharma, Diksha; Badal, Andreu; Badano, Aldo

2012-04-21

189

A Hybrid Monte Carlo-Deterministic Method for Global Binary Stochastic Medium Transport Problems  

Microsoft Academic Search

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,

K P Keady; P Brantley

2010-01-01

190

Adatom density kinetic Monte Carlo: A hybrid approach to perform epitaxial growth simulations  

Microsoft Academic Search

We describe an alternative approach to perform growth simulations that combines the kinetic Monte Carlo (KMC) method with elements from continuum and rate equations. Similar to the KMC method it takes the atomistic structure of the growing surface fully into account but is based on the adatom density rather than on explicit trajectories of the adatoms. As will be demonstrated,

L. Mandreoli; J. Neugebauer; R. Kunert; E. Schöll

2003-01-01

191

Modeling integrated cellular machinery using hybrid Petri-Boolean networks.  

PubMed

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

Berestovsky, Natalie; Zhou, Wanding; Nagrath, Deepak; Nakhleh, Luay

2013-11-01

192

Integrated power divider/combiner at hybrid orthogonal junctions  

NASA Astrophysics Data System (ADS)

We propose an integrated power divider/combiner at the interface between silicon nanowire and plasmonic slot waveguide (PSW). The proposed configuration facilitates light access and manipulation in planar nano-plasmonic circuits. The light is incident from a standard silicon nanowire to be accessed by a nano-plasmonic circuit providing subwavelength confinement. The structure overcomes the losses associated with long distance light propagation in nanoplasmonic splitters as coupling and splitting are performed at the same interface with minimal losses. Two PSWs placed orthogonally to the silicon nanowire forming hybrid junctions are exploited for the power dividing/combining functionality. The power splitter has been analyzed using the finite difference time domain (FDTD) numerical method. The ultra-compact proposed device provides wide-band power splitting functionality. A splitting of 34.7%, over most of the wavelength spectrum from 0.8 ?m - 2.5 ?m, is demonstrated.

El Sherif, Mohamed H.; Ahmed, Osman S.; Bakr, Mohamed H.

2014-03-01

193

Reliability evaluation of stand-alone hybrid microgrid using Sequential Monte Carlo Simulation  

Microsoft Academic Search

Adequacy assessment of a stand-alone microgrid including diesel generator (DG), Micro Gas Turbine(MGT), Wind Turbine Generator(WTG), and Photovoltaic(PV) with different configurations is carried out using Sequential Monte Carlo Simulation(SMCS) method. To obtain the output power of WTG and PV, some atmospheric data such as wind speed, solar irradiation, and ambient temperature data are needed. Weibull distribution is used to obtain

Mohammad Moradi Ghahderijani; S. Masoud Barakati; Saeed Tavakoli

2012-01-01

194

Path integral Monte Carlo with importance sampling for excitons interacting with an arbitrary phonon bath.  

PubMed

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. PMID:23249075

Shim, Sangwoo; Aspuru-Guzik, Alán

2012-12-14

195

Effect of Nonlinearity in Hybrid Kinetic Monte Carlo-Continuum Models  

SciTech Connect

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.

Balter, Ariel I.; Lin, Guang; Tartakovsky, Alexandre M.

2012-04-23

196

Torsional path integral Monte Carlo method for calculating the absolute quantum free energy of large molecules  

NASA Astrophysics Data System (ADS)

A new technique for evaluating the absolute free energy of large molecules is presented. Quantum-mechanical contributions to the intramolecular torsions are included via the torsional path integral Monte Carlo (TPIMC) technique. Importance sampling schemes based on uncoupled free rotors and harmonic oscillators facilitate the use of the TPIMC technique for the direct evaluation of quantum partition functions. Absolute free energies are calculated for the molecules ethane, n-butane, n-octane, and enkephalin, and quantum contributions are found to be significant. Comparison of the TPIMC technique with the harmonic oscillator approximation and a variational technique is performed for the ethane molecule. For all molecules, the quantum contributions to free energy are found to be significant but slightly smaller than the quantum contributions to internal energy.

Miller, Thomas F.; Clary, David C.

2003-07-01

197

Torsional path integral Monte Carlo method for the quantum simulation of large molecules  

NASA Astrophysics Data System (ADS)

A molecular application is introduced for calculating quantum statistical mechanical expectation values of large molecules at nonzero temperatures. The Torsional Path Integral Monte Carlo (TPIMC) technique applies an uncoupled winding number formalism to the torsional degrees of freedom in molecular systems. The internal energy of the molecules ethane, n-butane, n-octane, and enkephalin are calculated at standard temperature using the TPIMC technique and compared to the expectation values obtained using the harmonic oscillator approximation and a variational technique. All studied molecules exhibited significant quantum mechanical contributions to their internal energy expectation values according to the TPIMC technique. The harmonic oscillator approximation approach to calculating the internal energy performs well for the molecules presented in this study but is limited by its neglect of both anharmonicity effects and the potential coupling of intramolecular torsions.

Miller, Thomas F.; Clary, David C.

2002-05-01

198

Rotational ordering in solid deuterium and hydrogen: A path integral Monte Carlo study  

SciTech Connect

The path-integral Monte Carlo method with a constant-pressure ensemble is used to study both translational and orientational transitions in the phase diagram of D{sub 2} and H{sub 2} up to megabar pressures. With an intermolecular interaction potential determined to agree with the experimental equation of state, a rotational order-disorder phase transition is observed. The phase line for this transition is in quantitative agreement with part of the phase diagram for both D{sub 2} and H{sub 2}. No structural phase transition, and no transitions to the D-A and H-A phases (phase III) are observed. We attribute this in part to the limitations of simulation cell size. {copyright} {ital 1997} {ital The American Physical Society}

Cui, T.; Cheng, E. [Department of Chemistry, University of California, Berkeley, California 94720 (United States)] [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Alder, B.J. [Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States); Whaley, K.B. [Department of Chemistry, University of California, Berkeley, California 94720 (United States)] [Department of Chemistry, University of California, Berkeley, California 94720 (United States)

1997-05-01

199

Monte Carlo calculation of the quantum partition function via path integral formulations  

SciTech Connect

Using Bennett's Monte Carlo (MC) method, we calculate the quantum partition functions of path integral formulations. First, from numerically exact results for a harmonic oscillator and a double-well potential, we discuss how fast each approximate partition function converges to the exact value as the number of integral variables involved in the formulation is increased. It turns out that most effective and most suitable for the MC simulation is Takahashi and Imada's path integral fomulation based on a modified Trotter formula in which the original potential is replaced with an effective one. This formulation is well balanced between the following two factors: the effect of zero potential energy is underestimated, resulting in an improper increase in the partition function; and, on the other hand, effective potential restricts the motion of fictitious particles born in the formulation so that the partition function value tends to be smaller. Fictitious particles can be treated as classical ones. We therefore can apply Bennett's MC method to calculating the ratio of two quantum partition functions (of a system under consideration and a reference system). As the number of fictitious particles N is increased, choice of reference system becomes less and less important and multistage sampling becomes dispensable. This, to some extent, compensates for the expense that N is larger than the real particle number. The tunneling mechanism of fictitious particles in the simulation is discussed.

Kono, H.; Takasaka, A.; Lin, S.H.

1988-05-15

200

Equation of state of an interacting Bose gas at finite temperature: A path-integral Monte Carlo study  

Microsoft Academic Search

By using exact path-integral Monte Carlo methods we calculate the equation of state of an interacting Bose gas as a function of temperature both below and above the superfluid transition. The universal character of the equation of state for dilute systems and low temperatures is investigated by modeling the interatomic interactions using different repulsive potentials corresponding to the same s

S. Pilati; K. Sakkos; J. Boronat; J. Casulleras; S. Giorgini

2006-01-01

201

Calculation of the Shock Hugoniot of Deuterium at Pressures above 1 Mbar by the Path-Integral Monte Carlo Method  

SciTech Connect

The shock Hugoniot of deuterium at pressures above 1 Mbar is calculated by the path-integral Monte Carlo method without introducing additional physical assumptions and approximations. The results obtained are compared to calculations by other authors, various theoretical models, and experimental data.

Filinov, V.S.; Levashov, P.R.; Fortov, V.E. [Institute for High Energy Densities, Associated Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya ul. 13/19, Moscow, 125412 (Russian Federation); Bonitz, M. [Institute of Theoretical Physics and Astrophysics, University of Kiel, Kiel (Germany)

2005-08-15

202

Equation of state of an interacting Bose gas at finite temperature: A path-integral Monte Carlo study  

Microsoft Academic Search

By using exact path-integral Monte Carlo methods we calculate the equation of state of an interacting Bose gas as a function of temperature both below and above the superfluid transition. The universal character of the equation of state for dilute systems and low temperatures is investigated by modeling the interatomic interactions using different repulsive potentials corresponding to the same s-wave

S. Pilati; S. Giorgini; K. Sakkos; J. Boronat; J. Casulleras

2006-01-01

203

Path integral Monte Carlo studies of the H5+\\/D5+ clusters using ab initio potential surfaces  

Microsoft Academic Search

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.

P. Barragán; R. Pérez de Tudela; R. Prosmiti; P. Villarreal; G. Delgado-Barrio

2011-01-01

204

A Monte Carlo Application to Approximate the Integral from a to b of e Raised to the x Squared.  

ERIC Educational Resources Information Center

Proposes an alternative means of approximating the value of complex integrals, the Monte Carlo procedure. Incorporating a discrete approach and probability, an approximation is obtained from the ratio of computer-generated points falling under the curve to the number of points generated in a predetermined rectangle. (MDH)

Easterday, Kenneth; Smith, Tommy

1992-01-01

205

The Monte Carlo Integration Computer as an Instructional Model for the Simulation of Equilibrium and Kinetic Chemical Processes: The Development and Evaluation of a Teaching Aid.  

ERIC Educational Resources Information Center

A special purpose digital computer which utilizes the Monte Carlo integration method of obtaining simulations of chemical processes was developed and constructed. The computer, designated as the Monte Carlo Integration Computer (MCIC), was designed as an instructional model for the illustration of kinetic and equilibrium processes, and was…

Wood, Dean Arthur

206

Kinetic isotope effect in malonaldehyde determined from path integral Monte Carlo simulations.  

PubMed

The primary H/D kinetic isotope effect on the intramolecular proton transfer in malonaldehyde is determined from quantum instanton path integral Monte Carlo simulations on a fully dimensional and validated potential energy surface for temperatures between 250 and 1500 K. Our calculations, based on thermodynamic integration with respect to the mass of the transferring particle, are significantly accelerated by the direct evaluation of the kinetic isotope effect instead of computing it as a ratio of two rate constants. At room temperature, the KIE from the present simulations is 5.2 ± 0.4. The KIE is found to vary considerably as a function of temperature and the low-T behaviour is dominated by the fact that the free energy derivative in the reactant state increases more rapidly than in the transition state. Detailed analysis of the various contributions to the quantum rate constant together with estimates for rates from conventional transition state theory and from periodic orbit theory suggest that the KIE in malonaldehyde is dominated by zero point energy effects and that tunneling plays a minor role at room temperature. PMID:24233185

Huang, Jing; Buchowiecki, Marcin; Nagy, Tibor; Vaní?ek, Ji?í; Meuwly, Markus

2014-01-01

207

Interface defects in integrated hybrid semiconductors by wafer bonding  

NASA Astrophysics Data System (ADS)

The integration of materials by wafer bonding offers novel device fabrication for applications in micromechanics, microelectronics, and optoelectronics. Two mirror-polished surfaces are brought into intimate contact by adhesive forces regardless of their crystallography, crystalline orientation and lattice mismatch. Followed by a thermal treatment at several hundred degrees centigrade, the interface energy of the material combination is increased to energies of covalent interatomic bonds. Attempts to break the bond lead to fracturing of the materials. In particular, thermomechanic stress in dissimilar material combinations may result in bending, gliding and cracking of the bonded wafers during annealing. The bonding interface of various hybrid semiconductor materials was studied by transmission electron microscopy. Occasionally, microscopic imperfections at the bonding interface were found in Si/Si, Si/GaAs, GaAs/GaAs, GaAs/Al 2O 3, GaAs/InP and moreover Al 2O 3/Al 2O 3 bonded wafer pairs. The imperfections were identified as voids, negative crystals, and oxide-containing precipitates ranging from 5 to 20 nm in diameter. Microscopic defects at the bonding interface in integrated bulk materials do not affect the mechanical and electrical properties of the device very much. However, in bonding of thin films the defects or precipitates may thread through the thin film, if the diameter of the precipitate surpasses the thickness of the film. These pinholes-containing thin films have a high leakage current, low electrical breakthrough and crystallographic disorder. Epitaxy of material on a pinholes containing, disordered surface results on deposition of bicystalline grains. In between the grains tilt grain boundaries were observed raising from the bonding interface. Bonding related defects at the interface can be avoided by alternative bonding techniques like UHV wafer bonding and low temperature wafer bonding.

Kopperschmidt, P.; Senz, St.; Scholz, R.

2001-12-01

208

Design of a hybrid-integrated MEMS scanning grating spectrometer  

NASA Astrophysics Data System (ADS)

Optical MEMS (micro electro mechanical systems) have been used to reduce size, weight and costs of any kind of optical systems very successfully starting in the last decades. Scientists at Fraunhofer IPMS invented a resonant drive for 1-d and 2-d MEMS scanning mirror devices. Besides mirrors also scanning gratings have been realized. Now, rapidly growing new applications demand for enhanced functions and further miniaturization. This task cannot be solved by simply putting more functionality into the MEMS chip, for example grating and slit structures, but by three dimensional hybrid integration of the complete optical system into a stack of several functional substrates. Here we present the optical system design and realization strategy for a scanning grating spectrometer for the near infrared (NIR) range. First samples will be mounted from single components by a bonder tool (Finetech Fineplacer Femto) but the option of wafer assembly will be kept open for future developments. Extremely miniaturized NIR spectrometer could serve a wide variety of applications for handheld devices from food quality analysis to medical services or materials identification.

Pügner, Tino; Knobbe, Jens; Grüger, Heinrich; Schenk, Harald

2011-09-01

209

Equation of state of an interacting Bose gas at finite temperature: A path-integral Monte Carlo study  

SciTech Connect

By using exact path-integral Monte Carlo methods we calculate the equation of state of an interacting Bose gas as a function of temperature both below and above the superfluid transition. The universal character of the equation of state for dilute systems and low temperatures is investigated by modeling the interatomic interactions using different repulsive potentials corresponding to the same s-wave scattering length. The results obtained for the energy and the pressure are compared to the virial expansion for temperatures larger than the critical temperature. At very low temperatures we find agreement with the ground-state energy calculated using the diffusion Monte Carlo method.

Pilati, S.; Giorgini, S. [Dipartimento di Fisica, Universita di Trento and CRS-BEC INFM, I-38050 Povo (Italy); Sakkos, K.; Boronat, J.; Casulleras, J. [Departament de Fisica i Enginyeria Nuclear, Campus Nord B4-B5, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain)

2006-10-15

210

An Event-Driven Hybrid Molecular Dynamics and Direct Simulation Monte Carlo Algorithm  

SciTech Connect

A novel algorithm is developed for the simulation of polymer chains suspended in a solvent. The polymers are represented as chains of hard spheres tethered by square wells and interact with the solvent particles with hard core potentials. The algorithm uses event-driven molecular dynamics (MD) for the simulation of the polymer chain and the interactions between the chain beads and the surrounding solvent particles. The interactions between the solvent particles themselves are not treated deterministically as in event-driven algorithms, rather, the momentum and energy exchange in the solvent is determined stochastically using the Direct Simulation Monte Carlo (DSMC) method. The coupling between the solvent and the solute is consistently represented at the particle level, however, unlike full MD simulations of both the solvent and the solute, the spatial structure of the solvent is ignored. The algorithm is described in detail and applied to the study of the dynamics of a polymer chain tethered to a hard wall subjected to uniform shear. The algorithm closely reproduces full MD simulations with two orders of magnitude greater efficiency. Results do not confirm the existence of periodic (cycling) motion of the polymer chain.

Donev, A; Garcia, A L; Alder, B J

2007-07-30

211

Path-Integral Monte Carlo and the Squeezed Trapped Bose-Einstein Gas  

SciTech Connect

Bose-Einstein condensation has been experimentally found to take place in finite trapped systems when one of the confining frequencies is increased until the gas becomes effectively two-dimensional (2D). We confirm the plausibility of this result by performing path-integral Monte Carlo (PIMC) simulations of trapped Bose gases of increasing anisotropy and comparing them to the predictions of finite-temperature many-body theory. PIMC simulations provide an essentially exact description of these systems; they yield the density profile directly and provide two different estimates for the condensate fraction. For the ideal gas, we find that the PIMC column density of the squeezed gas corresponds quite accurately to that of the exact analytic solution and, moreover, is well mimicked by the density of a 2D gas at the same temperature; the two estimates for the condensate fraction bracket the exact result. For the interacting case, we find 2D Hartree-Fock solutions whose density profiles coincide quite well with the PIMC column densities and whose predictions for the condensate fraction are again bracketed by the PIMC estimates.

Fernandez, Juan Pablo [Department of Physics, University of Massachusetts, Amherst, MA 01003 (United States); Lebanon College, Lebanon, NH 03766 (United States); Mullin, William J. [Department of Physics, University of Massachusetts, Amherst, MA 01003 (United States)

2006-09-07

212

Spatial correlations in the electron gas: Path integral Monte Carlo simulation  

SciTech Connect

Thermally excited states of the three-dimensional electron gas in a neutralizing background are computed by path integral Monte Carlo simulation for values of the Wigner-Seitz radius within the interval 5 < r{sub s} < 15. Coulomb and exchange interactions, permutation symmetry, and spin state are treated explicitly. Variation of electron correlation functions with density and temperature is analyzed. Quantum effects suppress and enhance spatial correlation at low and high densities, respectively. Transition between the electron-gas states characterized by these opposite trends corresponds to a density of approximately 2.5 x 10{sup 21} cm{sup -3}. A transition line between liquid-like and gaslike phases is determined in the temperature-density diagram. Weak anisotropy of many-body correlations in the liquid-like state stimulates excitation of spherically symmetric collective rotational modes. The effective short-range pseudopotential exhibits strong temperature dependence due to exchange effects. For strongly correlated systems, the characteristic screening length deviates from that predicted by the Thomas-Fermi screening model ({approx}{radical}r{sub s}), approaching a linear function of r{sub s}. The effective short-range interaction substantially differs from the Yukawa potential in mean field theory. Coulomb interaction shifts the Fermi level up by an order of magnitude or higher, and this effect becomes stronger with decreasing density.

Shevkunov, S. V. [St. Petersburg State Polytechnic University (Russian Federation)], E-mail: root@svsh.tu.neva.ru

2006-07-15

213

A path-integral Monte Carlo study of a small cluster: The Ar trimer.  

PubMed

The Ar(3) 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 Ar(2)+Ar and Ar+Ar+Ar. Beyond T approximately 20 K, the system explores floppier configurations than the rigid equilateral geometry, as linear and Ar-Ar(2)-like arrangements, and fragmentates around T approximately 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 Ar(n) systems formed with more Ar atoms. Quantum mechanical effects are found of relevance at T

Pérez de Tudela, R; Márquez-Mijares, M; González-Lezana, T; Roncero, O; Miret-Artés, S; Delgado-Barrio, G; Villarreal, P

2010-06-28

214

Path Integral Monte Carlo Calculations of Thermodynamic Properties of Dense Hydrogen-Helium Plasma  

NASA Astrophysics Data System (ADS)

In this work we present new results of ab initio/ calculations of thermodynamic properties of dense hydrogen-helium plasma with helium concentration corresponding to that in the higher layers of the Jovian atmosphere at temperatures from 10^4 K to 2.10^5 K and electron particle densities from 10^20 to 10^24 cm-3. The calculations were made by path-integral Monte Carlo method in a cubical cell using periodic boundary conditions. To correctly take into account exchange effects at high values of the degeneracy parameter we used a special correcting procedure. At temperature higher than 5.10^4 K the calculation results are practically coincides with computations by the equation of state based on the chemical plasma model. However at temperatures 10^4 and 2.10^4 K in the density range from 0.5 to 5 g/cm^3 we found a phase transition region positioned in a good agreement with other theories and the experimentally revealed region of the sharp electrical conductivity rise. Along the isotherm 10^4 K in the density range from 0.01 to 0.2 g/cm^3 we found one more region of bad convergence to the equilibrium state. We also present first simulation results for helium plasma in comparison with other models and experimental data. The authors are grateful to the Russian Science support foundation for financial support of the work.

Filinov, Vladimir; Levashov, Pavel; Bonitz, Michael; Fortov, Vladimir

2005-07-01

215

Integration of partial least squares and Monte Carlo gene expression analysis in coronary artery disease  

PubMed Central

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.

ZHANG, HUAN; LI, TAO; WU, GUANJI; MA, FENG

2014-01-01

216

Monte Carlo simulation studies of lipid order parameter profiles near integral membrane proteins.  

PubMed Central

Monte Carlo simulation techniques have been applied to a statistical mechanical lattice model in order to study the coherence length for the spatial fluctuations of the lipid order parameter profiles around integral membrane proteins in dipalmitoyl phosphatidylcholine bilayers. The model, which provides a detailed description of the pure lipid bilayer main transition, incorporates hydrophobic matching between the lipid and protein hydrophobic thicknesses as a major contribution to the lipid-protein interactions in lipid membranes. The model is studied at low protein-to-lipid ratios. The temperature dependence of the coherence length is found to have a dramatic peak at the phase transition temperature. The dependence on protein circumference as well as hydrophobic length is determined and it is concluded that in some cases the coherence length is much longer than previously anticipated. The long coherence length provides a mechanism for indirect lipid-mediated protein-protein long-range attraction and hence plays an important role in regulating protein segregation. Images FIGURE 5 FIGURE 6

Sperotto, M M; Mouritsen, O G

1991-01-01

217

Path-integral Monte Carlo simulation of hydrogen in crystalline silicon  

NASA Astrophysics Data System (ADS)

Isolated hydrogen and deuterium in crystalline silicon have been studied by the path-integral Monte Carlo method. Interactions between Si atoms were modeled by the Stillinger-Weber potential, and the Si-H interaction was parametrized by following the results of earlier pseudopotential-density-functional calculations for this system. Finite-temperature properties of these point defects are analyzed in the range from 50 to 600 K. Hydrogen and deuterium are found to be stable at the bond-center (B) site. Average values of the kinetic and potential energy of the defect are compared with those expected for the impurity within a harmonic approximation. At low temperatures, is larger than , as a consequence of the strong anharmonicity of the potential surface for the impurity around the B site. The density distribution of the impurity at the B site displays axial symmetry around the Si-B-Si axis. The width of the density distribution along the bond direction is roughly one-half of that found for directions perpendicular to the symmetry axis.

Herrero, Carlos P.; Ramírez, Rafael

1995-06-01

218

Hybrid-integrated optical acceleration seismometer and its digital processing system  

Microsoft Academic Search

Hybrid-integrated Optical acceleration seismometer and its digital signal processing system are researched and developed. The simple system figure of the seismometer is given. The principle of the seismometer is explicated. The seismometer is composed of a seismic mass,Integrated Optical Chips and a set of Michelson interferometer light path. The Michelson Integrated Optical Chips are critical parts among the sensor elements.

De En; Caihe Chen; Yuming Cui; Donglin Tang; Zhengxi Liang; Hongyu Gao

2005-01-01

219

Design of hybrid long integration in Geo-location in presence of CCI  

Microsoft Academic Search

Due to cell planning in a cellular communication network, it is difficult for a mobile user in a cell to get ranging measurements from other neighboring cells. Consequently, it is necessary to enhance signal sensitivity using long integration techniques so that the user position is obtained by trilateration. In order to maximize integration gain in coherent\\/noncoherent hybrid long integration, it

Seung-Hun Song; Ji-Won Park; Tae-Kyung Sung

2010-01-01

220

Modelling and reduction techniques for studies of integrated hybrid vehicle systems  

Microsoft Academic Search

Models of integrated vehicle systems are essential for designing hybrid vehicles by means of simulation-based optimization. Given the complexity of hybrid vehicle systems, designing is a time consuming process that requires the evaluation of a large number of different design configurations. Modelling and simulation can significantly reduce the design time through efficient design evaluations and reduced number of prototypes built.

Loucas S. Louca; B. Umut Yildir

2006-01-01

221

Integrated graphene/nanoparticle hybrids for biological and electronic applications.  

PubMed

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. PMID:24752364

Nguyen, Kim Truc; Zhao, Yanli

2014-05-29

222

Integrated graphene/nanoparticle hybrids for biological and electronic applications  

NASA Astrophysics Data System (ADS)

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.

Nguyen, Kim Truc; Zhao, Yanli

2014-05-01

223

Integrated approach to diagnosis of complex hybrid systems  

NASA Astrophysics Data System (ADS)

This paper presents a model-based approach to diagnosis of hybrid systems. We have developed a combined qualitative-quantitative diagnosis scheme that uses hybrid models of the system and a model of the supervisory controller. By applying the supervisory controller model to diagnostic analysis we significantly cut down on the complexity in tracking behaviors, and in generating and refining hypotheses across discrete mode changes in the system behavior. We present the algorithms for hybrid diagnosis: hypotheses generation by back propagation, and hypotheses refinement by forward propagation and parameter estimation. Example scenarios demonstrate the effectiveness of this approach.

Narasimhan, Sriram; Biswas, Gautam; Karsai, Gabor

2001-07-01

224

Hybrid-integrated coherent receiver using silica-based planar lightwave circuit technology  

NASA Astrophysics Data System (ADS)

A hybrid-integrated coherent receiver module has been achieved using flip-chip bonding technology, consisting of a silica-based 90°-hybrid planar lightwave circuit (PLC) platform, a spot-size converter integrated waveguide photodiode (SSC-WG-PD), and a dual-channel transimpedance amplifier (TIA). The receiver module shows error-free operation up to 40Gb/s and OSNR sensitivity of 11.5 dB for BER = 10-3 at 25 Gb/s.

Kim, Jong-Hoi; Choe, Joong-Seon; Choi, Kwang-Seong; Youn, Chun-Ju; Kim, Duk-Jun; Jang, Sun-Hyok; Kwon, Yong-Hwan; Nam, Eun-Soo

2011-11-01

225

Application of ECSPN to RAMS modeling and analysis of hybrid drive systems  

Microsoft Academic Search

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

Steffen Nebel; A. Dieter; P. Muller; B. Bertsche

2010-01-01

226

Bose-Einstein condensation temperature of a homogeneous weakly interacting Bose gas: Path integral Monte Carlo study  

Microsoft Academic Search

Using a finite-temperature path integral Monte Carlo simulation (PIMC) method and finite-size scaling, we have investigated the interaction-induced shift of the phase-transition temperature for Bose-Einstein condensation of homogeneous weakly interacting Bose gases in three dimensions, which is given by a proposed analytical expression Tc=Tc0{1+c1an1\\/3+[c2'ln(an1\\/3)+c2\\

Kwangsik Nho; D. P. Landau

2004-01-01

227

Effective Potential Method in Path-Integral Monte Carlo Calculation and Application to 4He at T<=4 K  

Microsoft Academic Search

The effective potential method is proposed in the path integral Monte Carlo calculation for many-body system interacting with two-body potential. This method is formulated for bosons, fermions and distinguishable particles. There are three types of effective potentials in accordance with statistics of particles. This is applied to liquid 4He at the density 0.03626 mol\\/cm3 and lambda transition is reproduced in

Minoru Takahashi

1986-01-01

228

Variants of the Koksma-Hlawka inequality for vertex-modified quasi-Monte Carlo integration rules  

Microsoft Academic Search

Vertex-modified rules have recently been introduced by the authors as a way of improving the performance of quasi-Monte Carlo methods for numerical integration. In this paper, we establish variants of the Koksma-Hlawka inequality for vertex-modified rules, and we show that there are choices for the vertex weights which, in general, yield smaller error bounds than the classical Koksma-Hlawka bound. Low-discrepancy

I. H. Sloan

1996-01-01

229

Viral Hybrid Vectors for Somatic Integration - Are They the Better Solution?  

PubMed Central

The turbulent history of clinical trials in viral gene therapy has taught us important lessons about vector design and safety issues. Much effort was spent on analyzing genotoxicity after somatic integration of therapeutic DNA into the host genome. Based on these findings major improvements in vector design including the development of viral hybrid vectors for somatic integration have been achieved. This review provides a state-of-the-art overview of available hybrid vectors utilizing viruses for high transduction efficiencies in concert with various integration machineries for random and targeted integration patterns. It discusses advantages but also limitations of each vector system.

Muther, Nadine; Noske, Nadja; Ehrhardt, Anja

2009-01-01

230

Integrated Vacuum Growth System for Hybrid Organic-Inorganic Materials.  

National Technical Information Service (NTIS)

Our recent demonstrations of efficient inorganic-quantum-dot light- emitting devices in molecular organic hosts indicate the vast potential of hybrid organic/inorganic nanostructured materials for development of practical active devices. Experience shows ...

V. Bulovic

2004-01-01

231

LEDGF Hybrids Efficiently Retarget Lentiviral Integration Into Heterochromatin  

Microsoft Academic Search

Correction of genetic diseases requires integration of the therapeutic gene copy into the genome of patient cells. Retroviruses are commonly used as delivery vehicles because of their precise integration mechanism, but their use has led to adverse events in which vector integration activated proto-oncogenes and contributed to leukemogenesis. Here, we show that integration by lentiviral vectors can be targeted away

Rik Gijsbers; Keshet Ronen; Sofie Vets; Nirav Malani; Jan De Rijck; Melissa McNeely; Frederic D Bushman; Zeger Debyser

2010-01-01

232

Streamline Integration using MPI-Hybrid Parallelism on a Large Multi-Core Architecture  

SciTech Connect

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.

Camp, David; Garth, Christoph; Childs, Hank; Pugmire, Dave; Joy, Kenneth I.

2010-11-01

233

A new class of hybrid global optimization algorithms for peptide structure prediction: integrated hybrids  

NASA Astrophysics Data System (ADS)

A novel class of hybrid global optimization methods for application to the structure prediction in protein-folding problem is introduced. These optimization methods take the form of a hybrid between a deterministic global optimization algorithm, the ?BB, and a stochastically based method, conformational space annealing (CSA), and attempt to combine the beneficial features of these two algorithms. The ?BB method as previously extant exhibits consistency, as it guarantees convergence to the global minimum for twice-continuously differentiable constrained nonlinear programming problems, but can benefit from improvements in the computational front. Computational studies for met-enkephalin demonstrate the promise for the proposed hybrid global optimization method.

Klepeis, J. L.; Pieja, M. J.; Floudas, C. A.

2003-03-01

234

Path integral Monte Carlo studies of the H5+/D5+ clusters using ab initio potential surfaces  

NASA Astrophysics Data System (ADS)

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.

Barragán, P.; Pérez de Tudela, R.; Prosmiti, R.; Villarreal, P.; Delgado-Barrio, G.

2011-08-01

235

A hybrid approach to device integration on a genetic analysis platform  

NASA Astrophysics Data System (ADS)

Point-of-care (POC) systems require significant component integration to implement biochemical protocols associated with molecular diagnostic assays. Hybrid platforms where discrete components are combined in a single platform are a suitable approach to integration, where combining multiple device fabrication steps on a single substrate is not possible due to incompatible or costly fabrication steps. We integrate three devices each with a specific system functionality: (i) a silicon electro-wetting-on-dielectric (EWOD) device to move and mix sample and reagent droplets in an oil phase, (ii) a polymer microfluidic chip containing channels and reservoirs and (iii) an aqueous phase glass microarray for fluorescence microarray hybridization detection. The EWOD device offers the possibility of fully integrating on-chip sample preparation using nanolitre sample and reagent volumes. A key challenge is sample transfer from the oil phase EWOD device to the aqueous phase microarray for hybridization detection. The EWOD device, waveguide performance and functionality are maintained during the integration process. An on-chip biochemical protocol for arrayed primer extension (APEX) was implemented for single nucleotide polymorphism (SNiP) analysis. The prepared sample is aspirated from the EWOD oil phase to the aqueous phase microarray for hybridization. A bench-top instrumentation system was also developed around the integrated platform to drive the EWOD electrodes, implement APEX sample heating and image the microarray after hybridization.

Brennan, Des; Jary, Dorothee; Kurg, Ants; Berik, Evgeny; Justice, John; Aherne, Margaret; Macek, Milan; Galvin, Paul

2012-10-01

236

Evaluation of Monte Carlo Electron-Transport Algorithms in the Integrated Tiger Series Codes for Stochastic-Media Simulations  

NASA Astrophysics Data System (ADS)

Stochastic-media simulations require numerous boundary crossings. We consider two Monte Carlo electron transport approaches and evaluate accuracy with numerous material boundaries. In the condensed-history method, approximations are made based on infinite-medium solutions for multiple scattering over some track length. Typically, further approximations are employed for material-boundary crossings where infinite-medium solutions become invalid. We have previously explored an alternative "condensed transport" formulation, a Generalized Boltzmann-Fokker-Planck GBFP method, which requires no special boundary treatment but instead uses approximations to the electron-scattering cross sections. Some limited capabilities for analog transport and a GBFP method have been implemented in the Integrated Tiger Series (ITS) codes. Improvements have been made to the condensed history algorithm. The performance of the ITS condensed-history and condensed-transport algorithms are assessed for material-boundary crossings. These assessments are made both by introducing artificial material boundaries and by comparison to analog Monte Carlo simulations.

Franke, Brian C.; Kensek, Ronald P.; Prinja, Anil K.

2014-06-01

237

Application of the Monte Carlo integration (MCI) method for calculation of the anisotropy of 192Ir brachytherapy sources.  

PubMed

Source anisotropy is a very important factor in the brachytherapy quality assurance of high-dose rate (HDR) 192Ir afterloading stepping sources. If anisotropy is not taken into account then doses received by a brachytherapy patient in certain directions can be in error by a clinically significant amount. Experimental measurements of anisotropy are very labour intensive. We have shown that within acceptable limits of accuracy, Monte Carlo integration (MCI) of a modified Sievert integral (3D generalization) can provide the necessary data within a much shorter time scale than can experiments. Hence MCI can be used for routine quality assurance schedules whenever a new design of HDR or PDR 192Ir is used for brachytherapy afterloading. Our MCI calculation results are compared with published experimental data and Monte Carlo simulation data for microSelectron and VariSource 192Ir sources. We have shown not only that MCI offers advantages over alternative numerical integration methods, but also that treating filtration coefficients as radial distance-dependent functions improves Sievert integral accuracy at low energies. This paper also provides anisotropy data for three new 192Ir sources, one for the microSelectron-HDR and two for the microSelectron-PDR, for which data are currently not available. The information we have obtained in this study can be incorporated into clinical practice. PMID:9651040

Baltas, D; Giannouli, S; Garbi, A; Diakonos, F; Geramani, K; Ioannidis, G T; Tsalpatouros, A; Uzunoglu, N; Kolotas, C; Zamboglou, N

1998-06-01

238

Integration Profile and Safety of an Adenovirus Hybrid-Vector Utilizing Hyperactive Sleeping Beauty Transposase for Somatic Integration  

PubMed Central

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.

Zhang, Wenli; Muck-Hausl, Martin; Wang, Jichang; Sun, Chuanbo; Gebbing, Maren; Miskey, Csaba; Ivics, Zoltan; Izsvak, Zsuzsanna; Ehrhardt, Anja

2013-01-01

239

Integration profile and safety of an adenovirus hybrid-vector utilizing hyperactive sleeping beauty transposase for somatic integration.  

PubMed

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

Zhang, Wenli; Muck-Hausl, Martin; Wang, Jichang; Sun, Chuanbo; Gebbing, Maren; Miskey, Csaba; Ivics, Zoltan; Izsvak, Zsuzsanna; Ehrhardt, Anja

2013-01-01

240

Method of Moments Modeling of Single Layer Microstrip Patch Antennas using GPU Acceleration and Quasi-Monte Carlo Integration  

NASA Astrophysics Data System (ADS)

The development of a spectral domain method of moments code for the modeling of single layer microstrip patch antennas is presented in this thesis. The mixed potential integral equation formulation of Maxwell's equations is used as the theoretical basis for the work, and is solved via the method of moments. General-purpose graphics processing units are used for the computation of the impedance matrix by incorporation of quasi-Monte Carlo integration. The development of the various components of the code, including Green's function, impedance matrix, and excitation vector modules are discussed with individual test cases for the major code modules. The integrated code was tested by modeling a suite of four coaxially probe fed circularly polarized single layer microstrip patch antennas and the computed results are compared to those obtained by measurement. Finally, a study examining the relationship between design parameters and S11 performance was undertaken using the code.

Cerjanic, Alexander M.

241

Hybrid fuzzy proportional-integral plus conventional derivative control of linear and nonlinear systems  

Microsoft Academic Search

This paper presents a new approach toward the optimal design of a hybrid proportional-integral-derivative (PID) controller applicable for controlling linear as well as nonlinear systems using genetic algorithms (GAs). The proposed hybrid PID controller is derived by replacing the conventional PI controller by a two-input normalized linear fuzzy logic controller (FLC) and executing the conventional D controller in an incremental

Meng Joo Er; Ya Lei Sun

2001-01-01

242

Inversion of Schlumberger resistivity sounding data from the critically dynamic Koyna region using the Hybrid Monte Carlo-based neural network approach  

NASA Astrophysics Data System (ADS)

Koyna region is well-known for its triggered seismic activities since the hazardous earthquake of M=6.3 occurred around the Koyna reservoir on 10 December 1967. Understanding the shallow distribution of resistivity pattern in such a seismically critical area is vital for mapping faults, fractures and lineaments. However, deducing true resistivity distribution from the apparent resistivity data lacks precise information due to intrinsic non-linearity in the data structures. Here we present a new technique based on the Bayesian neural network (BNN) theory using the concept of Hybrid Monte Carlo (HMC)/Markov Chain Monte Carlo (MCMC) simulation scheme. The new method is applied to invert one and two-dimensional Direct Current (DC) vertical electrical sounding (VES) data acquired around the Koyna region in India. Prior to apply the method on actual resistivity data, the new method was tested for simulating synthetic signal. In this approach the objective/cost function is optimized following the Hybrid Monte Carlo (HMC)/Markov Chain Monte Carlo (MCMC) sampling based algorithm and each trajectory was updated by approximating the Hamiltonian differential equations through a leapfrog discretization scheme. The stability of the new inversion technique was tested in presence of correlated red noise and uncertainty of the result was estimated using the BNN code. The estimated true resistivity distribution was compared with the results of singular value decomposition (SVD)-based conventional resistivity inversion results. Comparative results based on the HMC-based Bayesian Neural Network are in good agreement with the existing model results, however in some cases, it also provides more detail and precise results, which appears to be justified with local geological and structural details. The new BNN approach based on HMC is faster and proved to be a promising inversion scheme to interpret complex and non-linear resistivity problems. The HMC-based BNN results are quite useful for the interpretation of fractures and lineaments in seismically active region.

Maiti, S.; Gupta, G.; Erram, V. C.; Tiwari, R. K.

2011-03-01

243

Ground-state path integral Monte Carlo simulations of positive ions in (4)He clusters: bubbles or snowballs?  

PubMed

The local order around alkali (Li(+) and Na(+)) and alkaline-earth (Be(+), Mg(+), and Ca(+)) ions in (4)He 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 (4)He shells coating the ions. As it was earlier suggested by experimental measurements in bulk (4)He, their findings indicate that Be(+) produces a solidlike ("snowball") structure, similar to alkali ions and in contrast to the more liquidlike (4)He structure embedding heavier alkaline-earth ions. PMID:17411133

Paolini, Stefano; Ancilotto, Francesco; Toigo, Flavio

2007-03-28

244

Path-integral Monte Carlo method for the local Z2 Berry phase.  

PubMed

We present a loop cluster algorithm Monte Carlo method for calculating the local Z(2) 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. PMID:23496453

Motoyama, Yuichi; Todo, Synge

2013-02-01

245

Path-integral Monte Carlo method for the local Z2 Berry phase  

NASA Astrophysics Data System (ADS)

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.

Motoyama, Yuichi; Todo, Synge

2013-02-01

246

Hybrid symplectic integrators for relativistic particles in electric and magnetic fields  

NASA Astrophysics Data System (ADS)

We develop a new implicit symplectic integrator and derive the first and second order integration algorithms for it. We combine this integrator with a Yoshida composition and with a Suzuki composition to get third order hybrid symplectic integrators. We test the algorithms on an exactly solvable example from McMillan (1950 Phys. Rev. 79 498) of a particle in an electromagnetic wave and find very good results, including long term stability and exact preservation of constants associated with symmetries. We discuss the circumstances in which the new algorithms may be useful.

Channell, Paul J.

2014-01-01

247

Hybrid Integrated Label-Free Chemical and Biological Sensors  

PubMed Central

Label-free sensors based on electrical, mechanical and optical transduction methods have potential applications in numerous areas of society, ranging from healthcare to environmental monitoring. Initial research in the field focused on the development and optimization of various sensor platforms fabricated from a single material system, such as fiber-based optical sensors and silicon nanowire-based electrical sensors. However, more recent research efforts have explored designing sensors fabricated from multiple materials. For example, synthetic materials and/or biomaterials can also be added to the sensor to improve its response toward analytes of interest. By leveraging the properties of the different material systems, these hybrid sensing devices can have significantly improved performance over their single-material counterparts (better sensitivity, specificity, signal to noise, and/or detection limits). This review will briefly discuss some of the methods for creating these multi-material sensor platforms and the advances enabled by this design approach.

Mehrabani, Simin; Maker, Ashley J.; Armani, Andrea M.

2014-01-01

248

The absorption spectrum of the solvated electron in fluid helium by maximum entropy inversion of imaginary time correlation functions from path integral Monte Carlo simulations  

Microsoft Academic Search

The dipole absorption spectrum of an electron in fluid helium is calculated by the maximum entropy method (MEM) numerical inversion of quantum Monte Carlo data obtained from a path integral Monte Carlo (PIMC) simulation at 309 K at the reduced densities &rgr;*=0.1, 0.3, 0.5, 0.7, and 0.9. Our results agree with the RISM-polaron theory results of Nichols and Chandler [A.

E. Gallicchio; B. J. Berne

1994-01-01

249

noloco: An efficient implementation of van der Waals density functionals based on a Monte-Carlo integration technique  

PubMed Central

The treatment of van der Waals interactions in density functional theory is an important field of ongoing research. Among different approaches developed recently to capture these non-local interactions, the van der Waals density functional (vdW-DF) developed in the groups of Langreth and Lundqvist is becoming increasingly popular. It does not rely on empirical parameters, and has been successfully applied to molecules, surface systems, and weakly-bound solids. As the vdW-DF requires the evaluation of a six-dimensional integral, it scales, however, unfavorably with system size. In this work, we present a numerically efficient implementation based on the Monte-Carlo technique for multi-dimensional integration. It can handle different versions of vdW-DF. Applications range from simple dimers to complex structures such as molecular crystals and organic molecules physisorbed on metal surfaces.

Nabok, Dmitrii; Puschnig, Peter; Ambrosch-Draxl, Claudia

2011-01-01

250

Design of a hybrid monolithic integrated switched capacitor DC-DC step-up converter  

Microsoft Academic Search

A 5 V\\/12 V switched capacitor (SC) DC-DC converter fabricated in a hybrid monolithic integration technology is presented. The technology combines a standard BiCMOS process with Al\\/Ta2O5\\/p-Si capacitor process to fabricate the DC-DC converter with larger capacitors. The topological design, property simulation and the integration process of the inductorless DC-DC converter are described in detail. This new design makes the

Li Geng; Zhiming Chen; Jian Liu

2000-01-01

251

High-speed optoelectronic hybrid-integrated transmitter module using a planar lightwave circuit (PLC) platform  

Microsoft Academic Search

High-speed optoelectronic hybrid-integrated transmitter module has been developed using a silica-based planar lightwave circuit (PLC) platform on which a laser diode (LD) array and a two-channel LD driver IC were integrated. Heat absorption through a highly thermal conductive silicon terrace kept the average output power constant to within 5% during IC operation. Bit-error-rate (BER) measurement showed that this module operated

S. Mino; T. Ohyama; Y. Akahori; M. Yanagisawa; T. Hashimoto; Y. Yamada; H. Tsunetsugu; M. Togashi; Y. Itaya; Y. Shibata

1998-01-01

252

Integration of ranked lists via cross entropy Monte Carlo with applications to mRNA and microRNA Studies.  

PubMed

One of the major challenges facing researchers studying complex biological systems is integration of data from -omics platforms. Omic-scale data include DNA variations, transcriptom profiles, and RAomics. Selection of an appropriate approach for a data-integration task is problem dependent, primarily dictated by the information contained in the data. In situations where modeling of multiple raw datasets jointly might be extremely challenging due to their vast differences, rankings from each dataset would provide a commonality based on which results could be integrated. Aggregation of microRNA targets predicted from different computational algorithms is such a problem. Integration of results from multiple mRNA studies based on different platforms is another example that will be discussed. Formulating the problem of integrating ranked lists as minimizing an objective criterion, we explore the usage of a cross entropy Monte Carlo method for solving such a combinatorial problem. Instead of placing a discrete uniform distribution on all the potential solutions, an iterative importance sampling technique is utilized "to slowly tighten the net" to place most distributional mass on the optimal solution and its neighbors. Extensive simulation studies were performed to assess the performance of the method. With satisfactory simulation results, the method was applied to the microRNA and mRNA problems to illustrate its utility. PMID:18479487

Lin, Shili; Ding, Jie

2009-03-01

253

Flight tests of a hybrid-centered integrated 3D perspective-view primary flight display  

NASA Astrophysics Data System (ADS)

This paper describes flight tests of a Honeywell Synthetic Vision System (SVS) prototype operating in a hybrid-centered mode on a Primus EpicTM large format display. This novel hybrid mode effectively resolves some cognitive and perceptual human factors issues associated with traditional heading-up or track-up display modes. By integrating synthetic 3D perspective view with advanced Head-Up Display (HUD) symbology in this mode, the test results demonstrate that the hybrid display mode provides clear indications of current track and crab conditions, and is effective in overcoming flight guidance symbology collision and resultant ambiguity. The hybrid-centering SVS display concept is shown to be effective in all phases of flight and is particularly valuable during landing operations with a strong cross-wind. The recorded flight test data from Honeywell's prototype SVS concept at Reno, Nevada on board Honeywell Citation V aircraft will be discussed.

He, Gang; Feyereisen, Thea; Wilson, Blake; Wyatt, Sandy; Engels, Jary

2006-06-01

254

Toward Data Confidentiality via Integrating Hybrid Encryption Schemes and Hadoop Distributed File System  

Microsoft Academic Search

With the increasing popularity of cloud computing, Hadoop has become a widely used open source cloud computing framework for large scale data processing. However, few studies have been done to enhance data confidentiality of Hadoop against storage servers. In this paper, we address the data confidentiality issue by integrating hybrid encryption schemes and the Hadoop distributed file system (HDFS). We

Hsiao-Ying Lin; Shiuan-Tzuo Shen; Wen-Guey Tzeng; Bao-Shuh P. Lin

2012-01-01

255

Planarized thin film inductors and capacitors for hybrid integrated circuits made of aluminum and anodic alumina  

Microsoft Academic Search

Planarized inductors and capacitors made of aluminum layers by electrochemical anodization technique have been tested in the frequency region of 1 kHz-300 MHz at temperatures of 293-473 K. These microcomponents can be used for high-frequency hybrid integrated circuits

Victor Surganov

1994-01-01

256

Hybrid simultaneous localization and map building: a natural integration of topological and metric  

Microsoft Academic Search

In this paper the metric and topological paradigms are integrated in a hybrid system for both localization and map building. A global topological map connects local metric maps, allowing a compact environment model, which does not require global metric consistency and permits both precision and robustness. Furthermore, the approach handles loops in the environment during automatic mapping by means of

Nicola Tomatis; Illah R. Nourbakhsh; Roland Siegwart

2003-01-01

257

An Integrated Hybrid Power Supply for Distributed Generation Applications Fed by Nonconventional Energy Sources  

Microsoft Academic Search

A new, hybrid integrated topology, fed by photovoltaic (PV) and fuel cell (FC) sources and suitable for distributed generation applications, is proposed. It works as an uninterruptible power source that is able to feed a certain minimum amount of power into the grid under all conditions. PV is used as the primary source of power operating near maximum power point

Sachin Jain; Vivek Agarwal

2008-01-01

258

DESIGN OF AN INTEGRATED HYBRID SYSTEM ARCHITECTURE FOR RISK ANALYSIS APPLICATIONS  

Microsoft Academic Search

The objective of this project was to establish a conceptual design for a hybrid system architecture for risk analysis. The design encompasses modules for both simulation (for project risk analysis) and probabilistic risk assessment (regarding safety issues). The knowledge base incorporates heuristics to integrate and interpret the algorithmic results. By utilizing the information from the expert system, in concert with

Gary P. Moynihan; Daniel J. Fonseca; Paul S. Ray

259

Fuel cell system integration into a heavy-duty hybrid vehicle: preliminary experimental results  

Microsoft Academic Search

This paper is the second paper dealing with the evaluation of different power sources and hybridization strategies in a heavy-duty vehicle. It focuses on the physical integration of a fuel cell system (FCS) into the vehicle as well as the preliminary experimental results obtained with the FCS coupled to batteries. The vehicle considered here is a mobile research platform (ECCE)

J. Mulot; F. Harel; S. Begot; D. Hissel; I. Rodel; S. Boblet; M. Amiet

2010-01-01

260

LOW COST IMPROVEMENTS TO BUILDING INTEGRATED AIR COOLED HYBRID PV-THERMAL SYSTEMS  

Microsoft Academic Search

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

Y. Tripanagnostopoulos; M. Souliotis

261

An HEMT with an integrated on-drain capacitor as basis of an hybrid mixer  

Microsoft Academic Search

This paper reports the study of an HEMT, the characteristic of which is to have a decoupling capacitor directly integrated between its drain and source electrodes. It is shown that, with an appropriate design of this basic filtering element, such a device proves to be efficient as for the realization of hybrid gate mixers. An experimental demonstration of this property

R. Allam; C. Kolanowski; D. Theron; Y. Crosnier

1995-01-01

262

Hybrid VCSEL modules with integrated amorphous silicon power monitors  

NASA Astrophysics Data System (ADS)

We present a novel optoelectronic package incorporating Vertical-Cavity Surface-Emitting Laser (VCSEL) arrays with built-in power monitors. The power monitor consists of a thin film amorphous silicon p-i-n photodetector that is fabricated on glass. Sets of micro-machined springs for electrical contacting are also fabricated in the same process on the same glass substrate. The springs are made by sputtering, masking, and releasing a stress-engineered conductive thin film. The stress-engineered film is patterned into electrical routing wires whose ends curl up into compliant springs when released from the substrate. Hybrid packages are formed by pressing the micro-machined springs against individual contact pads of the GaAs VCSEL array in a flip-chip assembly process. The power monitor is designed so it lies directly in front of the laser array in the path of the light after module assembly. Although only about 2% of the laser power is absorbed by the sensor, a large signal to noise ratio is retained because of the sensor"s extremely low dark current. Our typical laser output powers of about 1 mW at wavelengths of 811 nm produces power monitor photocurrents of 0.5 to 1 ?A, which, for our detectors, correspond to dynamic ranges of over five orders of magnitude.

Chua, Christopher L.; Lemmi, Francesco; Lu, Jeng-Ping

2004-06-01

263

Path-integral-expanded-ensemble Monte Carlo method in treatment of the sign problem for fermions.  

PubMed

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. PMID:20365297

Voznesenskiy, M A; Vorontsov-Velyaminov, P N; Lyubartsev, A P

2009-12-01

264

Mercedes-Benz water molecules near hydrophobic wall: Integral equation theories vs Monte Carlo simulations  

PubMed Central

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.

Urbic, T.; Holovko, M. F.

2011-01-01

265

Microwave Hybrid Integrated Circuit Applicatins of High Transition Temperature Superconductor  

NASA Astrophysics Data System (ADS)

This research work involves microwave characterization of high Tc superconducting (HTS) thin film using microstrip ring resonators, studying the nonlinear properties of HTS thin film transmission lines using two-tone intermodulation technique, coupling mechanisms and coupling factors of microstrip ring resonators side coupled to a microstrip line, two-port S-parameters measurements of GaAs MESFET at low temperature, and the design and implementation of hybrid ring resonator stabilized microwave oscillator using both metal films and superconducting films. A microstrip ring resonators operating at 10 GHz have been fabricated from YBCO HTS thin films deposited on one side of LaAl_2O_3 substrates. Below 60^circ Kelvin the measured unloaded Q of the HTS thin film microstrip ring resonators are more than 1.5 times that of gold film resonators. The two distinct but very close resonance peaks of a ring resonator side coupled to a microstrip line are experimentally identified as due to odd-mode and even-mode coupling. These two mechanisms have different characteristic equivalent circuit models and lead to different coupling coefficients and loaded resonance frequencies. The coupling factors for the two coupling modes are calculated using piecewise coupled line approximations. The two-port S-parameters measurement techniques and GaAs MESFET low temperature DC and microwave characteristics have been investigated. A system errors model including the errors caused by the line constriction at low temperature has been proposed and a temperature errors correction procedure has been developed for the two-port microwave S-parameters measurements at low temperature. The measured GaAs MESFET DC characteristics shows a 20% increase in transconductance at 77^circ K. There is also a 2 db increase in /S21/ at 77^circ K. The microwave oscillator stabilized with both metal and HTS thin film ring resonators have been studied. The tuning ability of the oscillator by a varactor diode has also been investigated. The phase noise performance of one side of the high Tc film oscillator does not show appreciable improvement over the gold film oscillator. With a varactor diode, the oscillator tuning range can be 300 MHz more. Two-tone intermodulation distortion (IMD) at 6.3 GHz in an HTS YBCO superconducting thin film microstrip transmission line on LaAl_2O _3 substrates are experimentally studied. At fixed input power, the 3rd order IMD power as function of temperature shows a minimum at a temperature around 60^circ Kelvin. With DC current applied, the second order IMD is observed and shows a strong functional dependance to the applied DC current and input power.

Lu, Shih-Lin

266

Acceleration of Monte Carlo modeling of light transport in turbid media; an approach based on hybrid, theoretical and numerical, calculations  

Microsoft Academic Search

A novel method to accelerate Monte Carlo (MC) simulations of photon migration in turbid media is presented. It is specifically suited for transillumination studies in slab geometries including some deep inhomogeneity. Propagation up to the inhomogeneity, at a given depth S1, is replaced by theoretical calculations using well established models. Then, photon propagation is continued inside the complete slab using

Héctor O. Di Rocco; Daniela I. Iriarte; Juan A. Pomarico; Héctor F. Ranea-Sandoval

2009-01-01

267

Path-integral representation for quantum spin models: Application to the quantum cavity method and Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

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.

Krzakala, Florent; Rosso, Alberto; Semerjian, Guilhem; Zamponi, Francesco

2008-10-01

268

Integrated Plasma Simulation of Lower Hybrid Current Drive in Tokamaks  

NASA Astrophysics Data System (ADS)

It has been shown in Alcator C-Mod that the onset time for sawteeth can be delayed significantly (up to 0.5 s) relative to ohmically heated plasmas, through the injection of off-axis LH current drive power [1]. We are simulating these experiments using the Integrated Plasma Simulator (IPS) [2], where the driven LH current density profiles are computed using a ray tracing component (GENRAY) and Fokker Planck code (CQL3D) [3] that are run in a tightly coupled time advance. The background plasma is evolved using the TSC transport code with the Porcelli sawtooth model [4]. Predictions of the driven LH current profiles will be compared with simpler ``reduced'' models for LHCD such as the LSC code which is implemented in TSC and which is also invoked within the IPS. [4pt] [1] C. E. Kessel et al, Bull. of the Am. Phys. Soc. 53, Poster PP6.00074 (2008). [0pt] [2] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008). [0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Meeting on Simulation and Modeling of Therm. Plasmas, Montreal, Canada (1992). [0pt] [4] S. C. Jardin et al, J. Comp. Phys. 66, 481 (1986).

Bonoli, P. T.; Wright, J. C.; Harvey, R. W.; Batchelor, D. B.; Berry, L. A.; Kessel, C. E.; Jardin, S. C.

2012-03-01

269

Ground-state path integral Monte Carlo simulations of positive ions in {sup 4}He clusters: Bubbles or snowballs?  

SciTech Connect

The local order around alkali (Li{sup +} and Na{sup +}) and alkaline-earth (Be{sup +}, Mg{sup +}, and Ca{sup +}) ions in {sup 4}He 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 {sup 4}He shells coating the ions. As it was earlier suggested by experimental measurements in bulk {sup 4}He, their findings indicate that Be{sup +} produces a solidlike ('snowball') structure, similar to alkali ions and in contrast to the more liquidlike {sup 4}He structure embedding heavier alkaline-earth ions.

Paolini, Stefano; Ancilotto, Francesco; Toigo, Flavio [Dipartimento di Fisica 'G. Galilei', Universita' di Padova, via Marzolo 8, I-35131 Padova, Italy and CNR-INFM-DEMOCRITOS National Simulation Center, Trieste (Italy)

2007-03-28

270

The theory of hybrid stochastic algorithms  

SciTech Connect

These lectures introduce the family of Hybrid Stochastic Algorithms for performing Monte Carlo calculations in Quantum Field Theory. After explaining the basic concepts of Monte Carlo integration we discuss the properties of Markov processes and one particularly useful example of them: the Metropolis algorithm. Building upon this framework we consider the Hybrid and Langevin algorithms from the viewpoint that they are approximate versions of the Hybrid Monte Carlo method; and thus we are led to consider Molecular Dynamics using the Leapfrog algorithm. The lectures conclude by reviewing recent progress in these areas, explaining higher-order integration schemes, the asymptotic large-volume behaviour of the various algorithms, and some simple exact results obtained by applying them to free field theory. It is attempted throughout to give simple yet correct proofs of the various results encountered. 38 refs.

Kennedy, A.D. (Florida State Univ., Tallahassee, FL (USA). Supercomputer Computations Research Inst.)

1989-11-21

271

Integration of SimSET photon history generator in GATE for efficient Monte Carlo simulations of pinhole SPECT  

PubMed Central

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.

Chen, Chia-Lin; Wang, Yuchuan; Lee, Jason J. S.; Tsui, Benjamin M. W.

2008-01-01

272

Field-hardened optical waveguide hybrid integrated-circuit multisensor chemical probe and its chemistry  

NASA Astrophysics Data System (ADS)

A single probe containing three hybrid integrated-circuit, optical waveguide, chemical-biochemical sensors (chip sensors) has been developed. Each chip sensor contains two hybrid waveguides -- one for sensing and one for reference. The sense waveguide is coated with a species-specific or group-specific chemistry or biochemistry. The reference waveguide is coated with a version of the sense chemistry or biochemistry, which is not sensitive to the analyte. The integrated structure is encapsulated and contains a single fixed light source, two detectors (reference and sense), and an optical train. The design is amenable to fluorescence, absorption, and refraction measurements. The three chip sensors are individually mounted in a probe that contains all of the electronics and computing capability necessary to collect and process the output information from each chip sensor. Only the surface of the individual chips are exposed to the target analytes. The probe is rugged, intrinsically safe, and can operate under 75 m (250 ft) of water.

Pollina, Richard J.; Himka, Roger L.; Saini, Devinder P.; McGibbon, Alan; Klainer, Stanley M.

1997-05-01

273

Path-integral Monte Carlo techniques for rotational motion in two dimensions: Quenched, annealed, and no-spin quantum-statistical averages  

Microsoft Academic Search

We provide a path-integral Monte Carlo (PIMC) technique for two-dimensional quantum rotators in static potentials. In our PIMC scheme we perform the summations over the different homotopy classes on the circle. In the case of a homonuclear diatomic molecule the coupling of nuclear spin and rotations due to the symmetry requirement of the total wave function is also taken into

D. Marx; P. Nielaba

1992-01-01

274

Monte Carlo ray-tracing simulations of luminescent solar concentrators for building integrated photovoltaics  

NASA Astrophysics Data System (ADS)

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.

Leow, Shin Woei; Corrado, Carley; Osborn, Melissa; Carter, Sue A.

2013-09-01

275

Modeling uncertainty in risk assessment: an integrated approach with fuzzy set theory and Monte Carlo simulation.  

PubMed

Modeling uncertainty during risk assessment is a vital component for effective decision making. Unfortunately, most of the risk assessment studies suffer from uncertainty analysis. The development of tools and techniques for capturing uncertainty in risk assessment is ongoing and there has been a substantial growth in this respect in health risk assessment. In this study, the cross-disciplinary approaches for uncertainty analyses are identified and a modified approach suitable for industrial safety risk assessment is proposed using fuzzy set theory and Monte Carlo simulation. The proposed method is applied to a benzene extraction unit (BEU) of a chemical plant. The case study results show that the proposed method provides better measure of uncertainty than the existing methods as unlike traditional risk analysis method this approach takes into account both variability and uncertainty of information into risk calculation, and instead of a single risk value this approach provides interval value of risk values for a given percentile of risk. The implications of these results in terms of risk control and regulatory compliances are also discussed. PMID:23567215

Arunraj, N S; Mandal, Saptarshi; Maiti, J

2013-06-01

276

Finding linear dependencies in integration-by-parts equations: A Monte Carlo approach  

NASA Astrophysics Data System (ADS)

The reduction of a large number of scalar integrals to a small set of master integrals via Laporta’s algorithm is common practice in multi-loop calculations. It is also a major bottleneck in terms of running time and memory consumption. It involves solving a large set of linear equations where many of the equations are linearly dependent. We propose a simple algorithm that eliminates all linearly dependent equations from a given system, reducing the time and space requirements of a subsequent run of Laporta’s algorithm.

Kant, Philipp

2014-05-01

277

40Gb\\/s All-Optical Processing Systems Using Hybrid Photonic Integration Technology  

Microsoft Academic Search

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

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

278

Performance analysis of an OTEC plant and a desalination plant using an integrated hybrid cycle  

Microsoft Academic Search

A performance analysis of an OTEC plant using an integrated hybrid cycle (I-H OTEC Cycle) has been conducted. The I-H OTEC cycle is a combination of a closed-cycle OTEC plant and a spray flash desalination plant. In an I-H OTEC cycle, warm sea water evaporates the liquid ammonia in the OTEC evaporator, then enters the flash chamber and evaporates itself.

Haruo Uehara; Akio Miyara; Yasuyuki Ikegami; Tsutomu Nakaoka

1996-01-01

279

Towards an Expansive Hybrid Psychology: Integrating Theories of the Mediated Mind  

Microsoft Academic Search

This article develops an integrative theory of the mind by examining how the mind, understood as a set of skills and dispositions,\\u000a depends upon four sources of mediators. Harré’s hybrid psychology is taken as a meta-theoretical starting point, but is expanded\\u000a significantly by including the four sources of mediators that are the brain, the body, social practices and technological\\u000a artefacts.

Svend Brinkmann

2011-01-01

280

Optimization of the dual energy-integration mechanism in a parallel-type hybrid vehicle  

Microsoft Academic Search

This research has designed a new hybrid-electric system, which is characterized by two mechanisms: internal-combustion engine energy-distribution mechanism and dual energy-integration mechanism. The internal-combustion engine energy-distribution mechanism comprises a first pulley-set and a second pulley-set, whereby it is possible to adjust its radius ratio and change the output load according to the road-surface, output speed and corresponding load to maintain

Sheng-Chung Tzeng; K. David Huang; Chia-Chang Chen

2005-01-01

281

Organic–Inorganic Hybrids for Light-Emitting Devices and Integrated Optics  

Microsoft Academic Search

This work provides an overview of the latest advances in organic–inorganic hybrid materials with applications in light-emitting\\u000a devices and integrated optics. The organization of the chapter intends to help the reader to gain a clear insight into the\\u000a topic, from the description of the material’s synthesis to the photoluminescence results that emphasize the potential technological\\u000a applications of these photonic materials

L. D. Carlos; R. A. Sá Ferreira

282

Advanced hybrid integrated low-power telemetric pressure monitoring system for biomedical applications  

Microsoft Academic Search

A new, highly miniaturized hybrid integrated solution for telemetric pressure measurement in biomedical applications is presented. The telemetrically powered ITES (Implantable Telemetric Endo-System) consists of a surface micro-machined capacitive type absolute pressure sensor fabricated in an eight-mask MOS-like process and two low-power ASICs for capacitance change read-out and telemetric data and energy transmission. An advanced flip-chip mounting and assembly technology

T. Eggers; C. Marschner; U. Marschner; B. Clasbrummel; R. Laur; J. Binder

2000-01-01

283

DAMPING OPTIMIZATION BY INTEGRATING ENHANCED ACTIVE CONSTRAINED LAYER AND ACTIVE-PASSIVE HYBRID CONSTRAINED LAYER TREATMENTS  

Microsoft Academic Search

The feasibility of integrating the enhanced active constrained layer (EACL) and active–passive hybrid constrained layer (HCL) treatments to achieve a better combination of the system's closed-loop damping and open-loop (fail-safe) damping (without active action) is investigated in this research. Given a uniform strain field in the host structure, the EACL with stiff and equal edge elements (symmetric EACL) has been

Y. Liu; K. W. WANG

2002-01-01

284

Optical Binary-Phase-Shift-Keying Modulation of 10 GHz Using an Integrated Hybrid Device  

Microsoft Academic Search

An integrated optical\\/RF hybrid device was designed and fabricated for binary-phase-shift-keying (BPSK) subcarrier modulation. The device is composed of two identical high-speed multiple quantum well electroabsorption modulators branched with two multimode interference couplers. Using the device, we demonstrated that a RF subcarrier of 10 GHz is directly modulated in a BPSK scheme with an independently applied RF carrier and digital

Myunghun Shin; Jiyoun Lim; Jeha Kim; Jeong-Soo Kim; Kwang-Eui Pyun; Songcheol Hong

2001-01-01

285

An integrated hybrid device for binary-phase-shift-keying subcarrier modulation  

Microsoft Academic Search

We propose an integrated optical\\/radio frequency (RF) hybrid device for binary-phase-shift-keying subcarrier modulation that is based on optical amplitude modulation and interference with phase delay. The device consists of two multiple-quantum-well (MQW) electroabsorption (EA) modulators branched with two multimode interference (MMI) couplers. When an RF carrier was applied to one modulator and a digital signal to the other one, the

M. Shin; J. Lim; C. Y. Park; J. Kim; J. S. Kim; K. E. Pyun; S. Hong

2000-01-01

286

Finite element methods with stable hybrid explicit-implicit time-integration schemes  

Microsoft Academic Search

Finite element methods with stable hybrid explicit-implicit time-integration schemes are reviewed. In particular, constructions that reduce to the well-known finite-difference time-domain (FDTD) scheme on structured grids of cubes are considered. Unstructured tetrahedrons with implicit time-stepping are used in the vicinity of curved and complex boundaries. The tetrahedrons are connected to the FDTD cells either directly or by means of a

T. Rylander

2007-01-01

287

DYNAMIC SIMULATION OF HYBRID FUEL CELL\\/MICRO TURBINE UNITS INTEGRATED INTO LARGE POWER SYSTEMS  

Microsoft Academic Search

The paper presents dynamic models and corresponding simulation results of hybrid fuel cell \\/ micro-turbine units integrated into the low-voltage part of a large network. It is assumed that up to 30% of the total electricity demand in the low-voltage area will be covered by these units. The study aims to highlight the dynamic interaction of several units with each

Ahmed M. Azmy; István Erlich

288

High performance and highly functional semiconductor optical amplifiers based on hybrid and monolithic integration  

Microsoft Academic Search

A higher level of functionality in semiconductor optical amplifiers is demonstrated through hybrid and monolithic integration. A booster optical amplifier (BOA) is packaged with input and output power monitoring capability. A fiberto-fiber gain of 14.6 dB is achieved. Saturation power of 20 dBm is demonstrated in the package. An optical bench is used to position different optical components, including the

Mario Dagenais; Peter S. Heim; Stewart W. Wilson; Simarjeet S. Saini; Dennis Bowler; Timothy Horton; Yimin Hu; Anthony Yu; R. Leavitt; Dennis R Stone; Vince Luciani; Frankie Rogers

2003-01-01

289

Color path-integral Monte-Carlo simulations of quark-gluon plasma: Thermodynamic and transport properties  

NASA Astrophysics Data System (ADS)

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.

Filinov, V. S.; Ivanov, Yu. B.; Fortov, V. E.; Bonitz, M.; Levashov, P. R.

2013-03-01

290

Quasi-Monte Carlo methods for the numerical integration of multivariate walsh series  

Microsoft Academic Search

In [1], a method for the numerical integration of multivariate Walsh series, based on low-discrepancy point sets, was developed. In the present paper, we improve and generalize error estimates given in [1] and disprove a conjecture stated in [1,2].

G. Larcher; W. Ch. Schmid; R. Wolf

1996-01-01

291

Quantifying Integrated Hydrologic Model Input and Parameter Uncertainty using Markov Chain Monte Carlo Simulations  

NASA Astrophysics Data System (ADS)

Modeling complex hydrologic systems requires increasingly complex models to sufficiently describe the physical mechanisms observed in the domain. Streamflow in our study area is primarily driven by climate, reservoirs, and surface and groundwater interactions. Hence in this study, we are using the coupled surface and groundwater flow model, GSFLOW, to simulate streamflow in the Truckee River basin, Nevada and California. To characterize this hydrologic system the model domain is discretized into ~10,500 grid cells of 300m resolution for which a priori parameter estimates from observed climate, soils, geology, and well logs along with parameters that are default were derived. Due to the high dimensionality of the problem, it is important to quantify model uncertainty from multiple sources (parameter, climate input). In the current study, we adopt a stepwise approach to calibrate the model and to quantify the uncertainty in the simulation of different hydro-meteorological fluxes. This approach is preferred firstly due to the availability of multiple observations such as precipitation, solar radiation, snow depth and snow water equivalent, remotely sensed snow cover, and observed streamflow. Secondly, by focusing on individual modules and the parameters associated with simulating one process (e.g. solar radiation) we reduce the parameter search space which improves the robustness of the search algorithm in identifying the global minimum. The Differential Evolution Adaptive Metropolis (DREAM) algorithm, which is a Markov Chain Monte Carlo (MCMC) sampler, is applied to the GSFLOW model in this step wise approach to quantify meteorological input and parameter uncertainty. Results from this approach, posterior parameter distributions for model parameters, and model uncertainty is presented. This analysis will not only produce a robust model, but will also help model developers understand non-linear relationships between model parameters and simulated processes.

Rajagopal, S.; Huntington, J. L.; Niswonger, R. G.; Reeves, M.; Pohll, G.

2012-12-01

292

Bose-Einstein condensation temperature of a homogeneous weakly interacting Bose gas: Path integral Monte Carlo study  

SciTech Connect

Using a finite-temperature path integral Monte Carlo simulation (PIMC) method and finite-size scaling, we have investigated the interaction-induced shift of the phase-transition temperature for Bose-Einstein condensation of homogeneous weakly interacting Bose gases in three dimensions, which is given by a proposed analytical expression T{sub c}=T{sub c}{sup 0}{l_brace}1+c{sub 1}an{sup 1/3}+[c{sub 2}{sup '} ln(an{sup 1/3})+c{sub 2}]a{sup 2}n{sup 2/3}+O(a{sup 3}n){r_brace}, where T{sub c}{sup 0} is the critical temperature for an ideal gas, a is the s-wave scattering length, and n is the number density. We have used smaller number densities and more time slices than in the previous PIMC simulations [Gruter et al., Phys. Rev. Lett. 79, 3549 (1997)] in order to understand the difference in the value of the coefficient c{sub 1} between their results and the (apparently) other reliable results in the literature. Our results show that {l_brace}(T{sub c}-T{sub c}{sup 0})/T{sub c}{sup 0}{r_brace}/(an{sup 1/3}) depends strongly on the interaction strength an{sup 1/3} while the previous PIMC results are considerably flatter and smaller than our results. We obtain c{sub 1}=1.32{+-}0.14, in agreement with results from recent Monte Carlo methods of three-dimensional O(2) scalar {phi}{sup 4} field theory and variational perturbation theory.

Nho, Kwangsik; Landau, D.P. [Center for Simulational Physics, University of Georgia, Athens, Georgia 30602 (United States)

2004-11-01

293

Extraction of diffuse correlation spectroscopy flow index by integration of Nth-order linear model with Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

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 < ±2%) from the noise-free DCS data than the semi-infinite solution (errors: -5.3% to -18.0%) for different tissue models. Although adding random noises to DCS data resulted in ?DB variations, the mean values of errors in extracting ?DB were similar to those reconstructed from the noise-free DCS data. In addition, the errors in extracting the relative changes of ?DB using both linear algorithm and semi-infinite solution were fairly small (errors < ±2.0%) and did not rely on the tissue volume/geometry. The experimental results from the in vivo stroke mice agreed with those in simulations, demonstrating the robustness of the linear algorithm. DCS with the high-order linear algorithm shows the potential for the inter-subject comparison and longitudinal monitoring of absolute BFI in a variety of tissues/organs with different volumes/geometries.

Shang, Yu; Li, Ting; Chen, Lei; Lin, Yu; Toborek, Michal; Yu, Guoqiang

2014-05-01

294

Optimal sizing of hybrid wind\\/photovoltaic\\/battery considering the uncertainty of wind and photovoltaic power using Monte Carlo  

Microsoft Academic Search

Using hybrid renewable energy is one of the best alternatives to supply the electrical energy at remote areas. Renewable energy sources are depended to weather conditions or other factors, so for supplying load with renewable sources appropriate capacity of these sources should be selected. In determining the capacity of renewable energy such as wind and solar, considering the stochastic nature

M. Bashir; J. Sadeh

2012-01-01

295

Simple pair-wise interactions for hybrid Monte Carlo-molecular dynamics simulations of titania/yttria-doped iron.  

PubMed

We present pair-wise, charge-neutral model potentials for an iron-titanium-yttrium-oxygen system. These simple models are designed to provide a tractable method of simulating nanostructured ferritic alloys (NFAs) using off-lattice Monte Carlo and molecular dynamics techniques without deviating significantly from the formalism employed in existing Monte Carlo simulations. The model is fitted to diamagnetic density functional theory (DFT) calculations of the various species over a range of densities and concentrations. The resulting model potentials provide reasonable and in some cases even excellent mechanical and thermodynamic properties for the pure metals. The model replicates the qualitative trends in formation energy predicted by DFT, though the energies of formation do not agree as well for dilute systems as they do for more concentrated systems. We find that on-lattice models will consistently favor tetrahedral oxygen interstitial sites over octahedral interstitial sites, while relaxed systems typically favor octahedral sites. This emphasizes the need for the off-lattice simulations for which this potential was designed. PMID:23288578

Hammond, Karl D; Voigt, Hyon-Jee Lee; Marus, Lauren A; Juslin, Niklas; Wirth, Brian D

2013-02-01

296

hybrid\\scriptsize{{MANTIS}}: a CPU-GPU Monte Carlo method for modeling indirect x-ray detectors with columnar scintillators  

NASA Astrophysics Data System (ADS)

The computational modeling of medical imaging systems often requires obtaining a large number of simulated images with low statistical uncertainty which translates into prohibitive computing times. We describe a novel hybrid approach for Monte Carlo simulations that maximizes utilization of CPUs and GPUs in modern workstations. We apply the method to the modeling of indirect x-ray detectors using a new and improved version of the code \\scriptsize{{MANTIS}}, an open source software tool used for the Monte Carlo simulations of indirect x-ray imagers. We first describe a GPU implementation of the physics and geometry models in fast\\scriptsize{{DETECT}}2 (the optical transport model) and a serial CPU version of the same code. We discuss its new features like on-the-fly column geometry and columnar crosstalk in relation to the \\scriptsize{{MANTIS}} code, and point out areas where our model provides more flexibility for the modeling of realistic columnar structures in large area detectors. Second, we modify \\scriptsize{{PENELOPE}} (the open source software package that handles the x-ray and electron transport in \\scriptsize{{MANTIS}}) to allow direct output of location and energy deposited during x-ray and electron interactions occurring within the scintillator. This information is then handled by optical transport routines in fast\\scriptsize{{DETECT}}2. A load balancer dynamically allocates optical transport showers to the GPU and CPU computing cores. Our hybrid\\scriptsize{{MANTIS}} approach achieves a significant speed-up factor of 627 when compared to \\scriptsize{{MANTIS}} and of 35 when compared to the same code running only in a CPU instead of a GPU. Using hybrid\\scriptsize{{MANTIS}}, we successfully hide hours of optical transport time by running it in parallel with the x-ray and electron transport, thus shifting the computational bottleneck from optical to x-ray transport. The new code requires much less memory than \\scriptsize{{MANTIS}} and, as a result, allows us to efficiently simulate large area detectors.

Sharma, Diksha; Badal, Andreu; Badano, Aldo

2012-04-01

297

Hybrid-integrated 4×4 optical gate matrix switch using silica-based optical waveguides and LD array chips  

Microsoft Academic Search

The fabrication and characteristics of a hybrid-integrated optical gate matrix switch were studied. The switch was composed of a silica-based single-mode guided-wave circuit and two InGaAsP gate array chips, each of which comprised eight laser diode optical gates. The gate array chips were assembled on the guided-wave circuit using a hybrid integration technique. The insertion loss of the fabricated 4×4

Yasufumi Yamada; Hiroshi Terui; Yasuji Ohmori; Makoto Yamada; Akira Himeno; Morio Kobayashi

1992-01-01

298

Implementing an Integrated Learning System for Hybrid Vehicle Technology: Supporting the Green Transportation  

NSDL National Science Digital Library

World competition and stringent United States fuel economy goals, and emission regulations for the 21st century vehicles, have pressured the automotive industry to design and evaluate advanced automobiles at an accelerated rate. The industry consensus is that the Hybrid Electric Vehicle (HEV) represents the currently available technology for increasing propulsion system efficiency and decreasing pollutant emissions. However, HEVs operate much differently than conventional vehicles. Therefore, existing design techniques and guidelines developed for conventional powertrains do not apply well to hybrid vehicles. There is a need for training automotive technicians and engineers as well as educating students in this new and emergent technology of HEV. This paper describes a funded project whose goal is to fill this need by developing integrated learning system for HEV technology. This project targets engineering/engineering technology students in 4-year universities, automotive technology students in community colleges, automotive engineers and technicians in industries, and technology teachers in secondary schools.

College, Wayne S.

299

Quantum rotation of Rb2 (3 ? {u/+}) attached to HeN droplets: a path-integral Monte Carlo study  

NASA Astrophysics Data System (ADS)

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.

Rodríguez-Cantano, Rocío; Pérez de Tudela, Ricardo; López-Durán, David; González-Lezana, Tomás; Gianturco, Franco A.; Delgado-Barrio, Gerardo; Villarreal, Pablo

2013-06-01

300

Path Integral Monte Carlo Study of X@C50 [X=H2, He, Ne, Ar  

NASA Astrophysics Data System (ADS)

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.

Peng, Chun; Zhang, Hong; Cheng, Xin-Lu

2013-11-01

301

Monte Carlo Simulations of Luminescent Solar Concentrators with Front-Facing Photovoltaic Cells for Building Integrated Photovoltaics  

NASA Astrophysics Data System (ADS)

Luminescent solar concentrators (LSCs) have the ability to receive light from a wide range of angles and concentrate the captured light on to small photo active areas. This enables LSCs to be integrated more extensively into buildings as windows and wall claddings on top of roof installations. LSCs with front facing PV cells collect both direct and concentrated light ensuring a gain factor greater than one. It also allows for flexibility in determining the placement and percentage coverage of PV cells when designing panels to balance reabsorption losses, power output and the level of concentration desired. A Monte-Carlo ray tracing program was developed to study the transport of photons and loss mechanisms in LSC panels and aid in design optimization. The program imports measured absorption/emission spectra and transmission coefficients as simulation parameters. Interactions of photons with the LSC panel are determined by comparing calculated probabilities with random number generators. Simulation results reveal optimal panel dimensions and PV cell layouts to achieve maximum power output.

Woei Leow, Shin; Corrado, Carley; Osborn, Melissa; Carter, Sue

2013-03-01

302

Path integral Monte Carlo study of 4He clusters doped with alkali and alkali-earth ions.  

PubMed

Path integral Monte Carlo calculations of (4)He nanodroplets doped with alkali (Na(+), K(+) and Cs(+)) and alkali-earth (Be(+) and Mg(+)) ions are presented. We study the system at T = 1 K and between 14 and 128 (4)He atoms. For all studied systems, we find that the ion is well localized at the center of the droplet with the formation of a "snowball" of well-defined shells of localized (4)He atoms forming solid-like order in at least the first surrounding shell. The number of surrounding helium shells (two or three) and the number of atoms per shell and the degree of localization of the helium atoms are sensitive to the type of ion. The number of (4)He atoms in the first shell varies from 12 for Na(+) to 18 for Mg(+) and depends weakly on the size of the droplet. The study of the density profile and of the angular correlations shows that the local solid-like order is more pronounced for the alkali ions with Na(+) giving a very stable icosahedral order extending up to three shells. PMID:21568337

Galli, D E; Ceperley, D M; Reatto, L

2011-06-30

303

Finite temperature path integral Monte Carlo simulations of structural and dynamical properties of Ar(N)-CO2 clusters.  

PubMed

We report finite temperature quantum mechanical simulations of structural and dynamical properties of Ar(N)-CO(2) clusters using a path integral Monte Carlo algorithm. The simulations are based on a newly developed analytical Ar-CO(2) 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 CO(2) molecule in Ar(N)-CO(2) 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 CO(2) vibrational frequency shift in different clusters. The first-solvation shell is completed at N = 17. Interestingly, our simulations for larger Ar(N)-CO(2) clusters showed several different structures of the argon shell around the doped CO(2) molecule. The observed two distinct peaks (2338.8 and 2344.5 cm(-1)) in the ?(3) band of CO(2) may be due to the different arrangements of argon atoms around the dopant molecule. PMID:22920121

Wang, Lecheng; Xie, Daiqian

2012-08-21

304

A core-softened fluid model in disordered porous media. Grand canonical Monte Carlo simulation and integral equations  

NASA Astrophysics Data System (ADS)

We have studied the microscopic structure and thermodynamic properties of a core-softened fluid model in disordered matrices of Lennard-Jones particles by using grand canonical Monte Carlo simulation. The dependence of density on the applied chemical potential (adsorption isotherms), pair distribution functions, as well as the heat capacity in different matrices are discussed. The microscopic structure of the model in matrices changes with density similar to the bulk model. Thus one should expect that the structural anomaly persists at least in dilute matrices. The region of densities for the heat capacity anomaly shrinks with increasing matrix density. This behavior is also observed for the diffusion coefficient on density from independent molecular dynamics simulation. Theoretical results for the model have been obtained by using replica Ornstein-Zernike integral equations with hypernetted chain closure. Predictions of the theory generally are in good agreement with simulation data, except for the heat capacity on fluid density. However, possible anomalies of thermodynamic properties for the model in disordered matrices are not captured adequately by the present theory. It seems necessary to develop and apply more elaborated, thermodynamically self-consistent closures to capture these features.

Pizio, Orest; Dominguez, Hector; Pusztai, Laszlo; Soko?owski, Stefan

2009-06-01

305

Heterogeneous Biomedical Database Integration Using a Hybrid Strategy: A p53 Cantcer Research Database  

PubMed Central

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.)

Bichutskiy, Vadim Y.; Colman, Richard; Brachmann, Rainer K.; Lathrop, Richard H.

2006-01-01

306

Sole means navigation and integrity through hybrid Loran-C and NAVSTAR GPS  

NASA Technical Reports Server (NTRS)

A sole means navigation system does not only call for integrity, but also for coverage, reliability, availability and accuracy. Even though ground monitored GPS will provide integrity, availability is still not sufficient. One satellite outage can affect a large service area for several hours per day. The same holds for differential GPS; a total satellite outage cannot be corrected for. To obtain sufficient coverage, extra measurements are needed, either in the form of extra GPS satellites (expensive) or through redundant measurements from other systems. LORAN-C is available and will, hybridized with GPS, result in a system that has the potential to satisfy the requirements for a sole means navigation system for use in the continental United States. Assumptions are made about the qualification sole means, mainly based on current sole means systems such as VOR/DME. In order to allow for system design that will satisfy sole means requirements, it is recommended that a definition of a sole means navigation system be established. This definition must include requirements for availability, reliability, and integrity currently not specified. In addition to the definition of a sole means navigation system, certification requirements must be established for hybrid navigation systems. This will allow for design and production of a new generation of airborne navigation systems that will reduce overall system costs and simplify training procedures.

Vangraas, Frank

1990-01-01

307

A Hybrid Monte Carlo Method Based Artificial Neural Networks Approach for Rock Boundaries Identification: A Case Study from the KTB Bore Hole  

NASA Astrophysics Data System (ADS)

Identification of rock boundaries and structural features from well log response is a fundamental problem in geological field studies. However, in a complex geologic situation, such as in the presence of crystalline rocks where metamorphisms lead to facies changes, it is not easy to discern accurate information from well log data using conventional artificial neural network (ANN) methods. Moreover inferences drawn by such methods are also found to be ambiguous because of the strong overlapping of well log signals, which are generally tainted with deceptive noise. Here, we have developed an alternative ANN approach based on Bayesian statistics using the concept of Hybrid Monte Carlo (HMC)/Markov Chain Monte Carlo (MCMC) inversion scheme for modeling the German Continental Deep Drilling Program (KTB) well log data. MCMC algorithm draws an independent and identically distributed (i.i.d) sample by Markov Chain simulation technique from posterior probability distribution using the principle of statistical mechanics in Hamiltonian dynamics. In this algorithm, each trajectory is updated by approximating the Hamiltonian differential equations through a leapfrog discrimination scheme. We examined the stability and efficiency of the HMC-based approach on “noisy” data assorted with different levels of colored noise. We also perform uncertainty analysis by estimating standard deviation (STD) error map of a posteriori covariance matrix at the network output of three types of lithofacies over the entire length of the litho section of KTB. Our analyses demonstrate that the HMC-based approach renders robust means for classification of complex lithofacies successions from the KTB borehole noisy signals, and hence may provide a useful guide for understanding the crustal inhomogeneity and structural discontinuity in many other tectonically critical and complex regions.

Maiti, Saumen; Tiwari, R. K.

2009-11-01

308

Hybrid Monte Carlo self-consistent field approach to model a thin layer of a polyelectrolyte gel near an adsorbing surface.  

PubMed

The use of thin layers of a surface bound (polyelectrolyte) hydrogels for measuring the concentration of metal ions from electrolyte solutions is our motivation for modeling such hydrogels. The gels are composed of polymeric species with conformational degrees of freedom on the nanometer scale. The polymer conformations are affected by the presence of cross-links in the gel on a five to ten times larger length scale, and the repulsive interactions generated by the charges along the chains. Here we present a hybrid computational Monte Carlo Self-consistent field (MC-SCF) approach to model such hydrogels. The SCF formalism is used to evaluate the conformational properties of the chains, implementing a freely jointed chain model, in between featureless cross-links. The Monte Carlo simulation method is used to sample the (restricted) translational degrees of freedom of the cross-links in the gel. We consider the case that the polymers in the gel have an affinity for surface positioned at the edge of the simulation volume. The polymer density decays as a power-law from the surface to the gel-density with an exponent close to -4/3. The gel features relatively large density fluctuations which is natural for a gel with a low density (? ? 0.035), a low degree of cross-linking (average of three chainparts per cross-link), and relatively large chains (N = 50) in between the cross-links. Some parts of the gel can break loose from the gel and sample the adjoining volume. Representative snapshots exemplify large density fluctuations, which explain the large pore size distribution observed in experimental counterparts. PMID:22397698

Leermakers, F A M; Bergsma, J; van der Gucht, J

2012-06-28

309

Hybrid integration of synthesized dielectric image waveguides in substrate integrated circuit technology and its millimeter wave applications  

NASA Astrophysics Data System (ADS)

This thesis deals with a novel type of integrated dielectric waveguide which is synthesized on a planar grounded substrate by perforation of the zones adjacent to a guiding channel in the center. The resulting Substrate Integrated Image Guide (SIIG) not only allows for low-loss guidance of electromagnetic waves in a similar way as the standard image guide, but also meets the requirements of low cost and ease of integration. A first objective was the detailed analysis of the propagation properties of fundamental and higher order modes in this waveguide structure, regarding attenuation, dispersion behavior, bandwidth, leakage effects, and the impact of fabrication tolerances. For this purpose, specifically adapted techniques of analysis are presented, since established methods for the conventional image guide can not be applied to the more complex periodic SIIG. Commercial electromagnetic full-wave software is used along with a dual-line approach involving a subsequent extraction of the propagation constant from simulated S-parameters. Alternatively, the solution of the eigenmode problem of a single SIIG unit cell also performs the task. Both techniques are in good agreement and provide accurate results, which is supported by measurements on laser-fabricated prototypes. It is shown that the achievable attenuation is much lower than in the standard integrated technologies and that losses mainly depend on the chosen dielectric material. As a consequence, the SIIG also is an attractive technology for applications beyond the mmW band, i. e. in the terahertz range. Design recommendations for the geometric parameters of the SIIG are discussed and a simplified equivalent model with homogeneous dielectric regions is introduced to speed up the design of passive components. Low-loss transitions between dissimilar waveguide structures are indispensable key components for a hybrid integrated platform. In order to enable the connection of standard measurement equipment in the W-band (75 GHz to 110 GHz), a transition from rectangular waveguide to SIIG was developed. Another transition to either microstrip or CPW is essential to enable coplanar probe measurements and to achieve compatibility with monolithic millimeter wave integrated circuits (MMICs). Microstrip and image guide have very different requirements for the substrate thickness, for which reason efforts were concentrated on a wideband transition between the SIIG and CPW. The designed transition shows good broadband performance and minimal radiation loss. Other transitions from the SIIG to the Substrate Integrated Waveguide (SIW) are also presented in the context of substrate integrated circuits (SICs). The latter technology combines planar transmission lines and originally non-planar waveguide structures that are synthesized in planar form on a common substrate. High alignment precision is a direct consequence, which eliminates the necessity for additional tuning. As an open dielectric waveguide technology with very small transmission loss, the SIIG is particularly suitable for antennas and corresponding feed lines. The similarity of the SIIG with other dielectric waveguides and especially with the image guide suggests a knowledge transfer from known dielectric antennas. A planar SIIG rod antenna was designed and fabricated, as a derivative of the established polyrod antenna. The structural shape is simple and compact, and it provides a medium gain in the range of 10 dBi to 15 dBi. A second developed type, an SIIG traveling-wave linear array antenna, is frequency-steerable through broadside due to special radiation elements. The novel design of a slab-mode antenna forms an endfire beam by a planar lens configuration. In addition, all of those dielectric-based antennas are highly efficient. Being synthesized on a planar substrate, the SIIG can be combined in a hybrid way with other waveguide structures on the same substrate in so-called substrate integrated circuits (SICs). It joins the SIW and the Substrate Integrated Non-Radiative Dielectric guide (SINRD) and adds unique featu

Patrovsky, Andreas

310

Development of CdTe hybrid detector with CMOS charge integration amplifier  

NASA Astrophysics Data System (ADS)

A pixelated CdTe detector module is being developed for use in X-ray imaging application. The CdTe is expected to allow higher energy detection capability because of the high atomic number. And also, high resolution imaging becomes possible with a direct conversion method in which an incident X-ray photon is directly converted to electric charges. This paper reports the first results of a 50 ?m pitch, 64×64 pixels, CdTe hybrid imaging module with CMOS charge integration readout ASIC with a flip chip bonding technique.

Fujita, K.; Matsue, K.; Ichikawa, M.; Yamamoto, K.

2011-04-01

311

Progress of Integral Experiments in Benchmark Fission Assemblies for a Blanket of Hybrid Reactor  

NASA Astrophysics Data System (ADS)

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.

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

312

Organic-Inorganic Eu3+/Tb3+ codoped hybrid films for temperature mapping in integrated circuits  

PubMed Central

The continuous decrease on the geometric size of electronic devices and integrated circuits generates higher local power densities and localized heating problems that cannot be characterized by conventional thermographic techniques. Here, a self-referencing intensity-based molecular thermometer involving a di-ureasil organic-inorganic hybrid thin film co-doped with Eu3+ and Tb3+ tris (?-diketonate) chelates is used to obtain the temperature map of a FR4 printed wiring board with spatio-temporal resolutions of 0.42 ?m/4.8 ms.

Brites, Carlos D. S.; Lima, Patricia P.; Silva, Nuno J. O.; Millan, Angel; Amaral, Vitor S.; Palacio, Fernando; Carlos, Luis D.

2013-01-01

313

Cascaded all-optical operations in a hybrid integrated 80-Gb/s logic circuit.  

PubMed

We demonstrate logic functionalities in a high-speed all-optical logic circuit based on differential Mach-Zehnder interferometers with semiconductor optical amplifiers as the nonlinear optical elements. The circuit, implemented by hybrid integration of the semiconductor optical amplifiers on a planar lightwave circuit platform fabricated in silica glass, can be flexibly configured to realize a variety of Boolean logic gates. We present both simulations and experimental demonstrations of cascaded all-optical operations for 80-Gb/s on-off keyed data. PMID:24921554

LeGrange, J D; Dinu, M; Sochor, T; Bollond, P; Kasper, A; Cabot, S; Johnson, G S; Kang, I; Grant, A; Kay, J; Jaques, J

2014-06-01

314

All-fiber hybrid photon-plasmon circuits: integrating nanowire plasmonics with fiber optics.  

PubMed

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

Li, Xiyuan; Li, Wei; Guo, Xin; Lou, Jingyi; Tong, Limin

2013-07-01

315

Hybrid III/V silicon photonic source with integrated 1D free-space beam steering.  

PubMed

A chip-scale optical source with integrated beam steering is demonstrated. The chip was fabricated using the hybrid silicon platform and incorporates an on-chip laser, waveguide splitter, amplifiers, phase modulators, and surface gratings to comprise an optical phased array with beam steering across a 12° field of view in one axis. Tuning of the phased array is used to achieve 1.8°(steered axis)×0.6°(nonsteered axis) beam width with 7 dB background suppression for arbitrary beam direction within the field of view. PMID:23073429

Doylend, J K; Heck, M J R; Bovington, J T; Peters, J D; Davenport, M L; Coldren, L A; Bowers, J E

2012-10-15

316

An integrated kinetic Monte Carlo molecular dynamics approach for film growth modeling and simulation: ZrO 2 deposition on Si (1 0 0) surface  

Microsoft Academic Search

In this paper we present a novel integrated approach, which combines kinetic Monte Carlo and molecular dynamics (kMC-MD) methods, and its application in modeling initial steps of ZrO2 film growth on Si(100) surface. The modification of kMC for non-regular structures consists in dynamical determination of chemical structure at the energy minimization (surface relaxation) step using known and newly developed force

A. A. Knizhnik; A. A. Bagaturyants; I. V. Belov; B. V. Potapkin; A. A. Korkin

2002-01-01

317

Microfluidic chip integrating high throughput continuous-flow PCR and DNA hybridization for bacteria analysis.  

PubMed

Rapid identification of clinical pathogens is the initial and essential step for antimicrobial therapy. Herein, we successfully developed a microfluidic device which combines high-throughput continuous-flow PCR and DNA hybridization for the detection of various bacterial pathogens. Universal primers were designed based on the conserved regions of bacterial 16S ribosomal DNA (16S rDNA), and specific probes were designed from a variable region of 16S rDNA within the amplicon sequences. In the chip operation, after the continuous flow PCR was achieved in the first microfluidic chip, the product was directly introduced into a hybridization chip integrated with microarray containing the immobilized DNA probes. The target-probe hybridization was completed within 1h at 55°C, and fluorescence signals were obtained as the readout. The presented device is simple, versatile and with less sample consumption compared with traditional instruments. It can perform high-throughput bacteria detections continuously in a single assay, which makes it a promising platform for clinical bacteria identifications. PMID:24720991

Jiang, Xiran; Shao, Ning; Jing, Wenwen; Tao, Shengce; Liu, Sixiu; Sui, Guodong

2014-05-01

318

A hybrid approach to protein folding problem integrating constraint programming with local search  

PubMed Central

Background The protein folding problem remains one of the most challenging open problems in computational biology. Simplified models in terms of lattice structure and energy function have been proposed to ease the computational hardness of this optimization problem. Heuristic search algorithms and constraint programming are two common techniques to approach this problem. The present study introduces a novel hybrid approach to simulate the protein folding problem using constraint programming technique integrated within local search. Results Using the face-centered-cubic lattice model and 20 amino acid pairwise interactions energy function for the protein folding problem, a constraint programming technique has been applied to generate the neighbourhood conformations that are to be used in generic local search procedure. Experiments have been conducted for a few small and medium sized proteins. Results have been compared with both pure constraint programming approach and local search using well-established local move set. Substantial improvements have been observed in terms of final energy values within acceptable runtime using the hybrid approach. Conclusion Constraint programming approaches usually provide optimal results but become slow as the problem size grows. Local search approaches are usually faster but do not guarantee optimal solutions and tend to stuck in local minima. The encouraging results obtained on the small proteins show that these two approaches can be combined efficiently to obtain better quality solutions within acceptable time. It also encourages future researchers on adopting hybrid techniques to solve other hard optimization problems.

2010-01-01

319

Integration Issues of Cells into Battery Packs for Plug-in and Hybrid Electric Vehicles: Preprint  

SciTech Connect

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.

Pesaran, A. A.; Kim, G. H.; Keyser, M.

2009-05-01

320

The ObjECTS: Framework for Integrated Assessment: Hybrid Modeling of Transportation  

SciTech Connect

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.

Kim, Son H.; Edmonds, James A.; Lurz, Joshua; Smith, Steven J.; Wise, Marshall A.

2006-09-01

321

Structural Heterogeneity and Quantitative FRET Efficiency Distributions of Polyprolines through a Hybrid Atomistic Simulation and Monte Carlo Approach  

PubMed Central

Förster Resonance Energy Transfer (FRET) experiments probe molecular distances via distance dependent energy transfer from an excited donor dye to an acceptor dye. Single molecule experiments not only probe average distances, but also distance distributions or even fluctuations, and thus provide a powerful tool to study biomolecular structure and dynamics. However, the measured energy transfer efficiency depends not only on the distance between the dyes, but also on their mutual orientation, which is typically inaccessible to experiments. Thus, assumptions on the orientation distributions and averages are usually made, limiting the accuracy of the distance distributions extracted from FRET experiments. Here, we demonstrate that by combining single molecule FRET experiments with the mutual dye orientation statistics obtained from Molecular Dynamics (MD) simulations, improved estimates of distances and distributions are obtained. From the simulated time-dependent mutual orientations, FRET efficiencies are calculated and the full statistics of individual photon absorption, energy transfer, and photon emission events is obtained from subsequent Monte Carlo (MC) simulations of the FRET kinetics. All recorded emission events are collected to bursts from which efficiency distributions are calculated in close resemblance to the actual FRET experiment, taking shot noise fully into account. Using polyproline chains with attached Alexa 488 and Alexa 594 dyes as a test system, we demonstrate the feasibility of this approach by direct comparison to experimental data. We identified cis-isomers and different static local environments as sources of the experimentally observed heterogeneity. Reconstructions of distance distributions from experimental data at different levels of theory demonstrate how the respective underlying assumptions and approximations affect the obtained accuracy. Our results show that dye fluctuations obtained from MD simulations, combined with MC single photon kinetics, provide a versatile tool to improve the accuracy of distance distributions that can be extracted from measured single molecule FRET efficiencies.

Hoefling, Martin; Lima, Nicola; Haenni, Dominik; Seidel, Claus A. M.; Schuler, Benjamin; Grubmuller, Helmut

2011-01-01

322

Fully integrated hybrid silicon free-space beam steering source with 32-channel phased array  

NASA Astrophysics Data System (ADS)

Free-space beam steering using optical phased arrays is a promising method for implementing free-space communication links and Light Detection and Ranging (LIDAR) without the sensitivity to inertial forces and long latencies which characterize moving parts. Implementing this approach on a silicon-based photonic integrated circuit adds the additional advantage of working with highly developed CMOS processing techniques. In this work we discuss our progress in the development of a fully integrated 32 channel PIC with a widely tunable diode laser, a waveguide phased array, an array of fast phase modulators, an array of hybrid III-V/silicon amplifiers, surface gratings, and a graded index lens (GRIN) feeding an array of photodiodes for feedback control. The PIC has been designed to provide beam steering across a 15°x5° field of view with 0.6°x0.6° beam width and background peaks suppressed 15 dB relative to the main lobe within the field of view for arbitrarily chosen beam directions. Fabrication follows the hybrid silicon process developed at UCSB with modifications to incorporate silicon diodes and a GRIN lens.

Hulme, J. C.; Doylend, J. K.; Heck, M. J. R.; Peters, J. D.; Davenport, M. L.; Bovington, J. T.; Coldren, L. A.; Bowers, J. E.

2014-03-01

323

A Hybrid Neuro-Fuzzy Model For Integrating Large Earth-Science Datasets  

NASA Astrophysics Data System (ADS)

A GIS-based hybrid neuro-fuzzy approach to integration of large earth-science datasets for mineral prospectivity mapping is described. It implements a Takagi-Sugeno type fuzzy inference system in the framework of a four-layered feed-forward adaptive neural network. Each unique combination of the datasets is considered a feature vector whose components are derived by knowledge-based ordinal encoding of the constituent datasets. A subset of feature vectors with a known output target vector (i.e., unique conditions known to be associated with either a mineralized or a barren location) is used for the training of an adaptive neuro-fuzzy inference system. Training involves iterative adjustment of parameters of the adaptive neuro-fuzzy inference system using a hybrid learning procedure for mapping each training vector to its output target vector with minimum sum of squared error. The trained adaptive neuro-fuzzy inference system is used to process all feature vectors. The output for each feature vector is a value that indicates the extent to which a feature vector belongs to the mineralized class or the barren class. These values are used to generate a prospectivity map. The procedure is demonstrated by an application to regional-scale base metal prospectivity mapping in a study area located in the Aravalli metallogenic province (western India). A comparison of the hybrid neuro-fuzzy approach with pure knowledge-driven fuzzy and pure data-driven neural network approaches indicates that the former offers a superior method for integrating large earth-science datasets for predictive spatial mathematical modelling.

Porwal, A.; Carranza, J.; Hale, M.

2004-12-01

324

Site-specific integration mediated by a hybrid adenovirus/adeno-associated virus vector  

PubMed Central

Adenovirus (Ad) and adeno-associated virus (AAV) have attractive and complementary properties that can be exploited for gene transfer purposes. Ad vectors are probably the most efficient vehicles to deliver foreign genes both in vitro and in vivo. AAV exhibits the unique ability to establish latency by efficiently integrating at a specific locus of human chromosome 19 (AAVS1). Two viral elements are necessary for the integration at AAVS1: Rep68/78 and the inverted terminal repeats (AAV-ITRs). In this study, we report the development of two helper-dependent adenoviral (HD) vectors, one carrying the Rep78 gene, the other an AAV-ITR-flanked transgene. Although Rep proteins have been demonstrated to interfere with Ad replication, HD Rep78 vector was successfully amplified on serial passages in 293CRE4 cells with a yield of 50–100 transducing units per cell. DNA integration at the AAVS1 site also was demonstrated in hepatoma cells coinfected with the HD-expressing Rep78 and with the second HD vector carrying a transgene flanked by AAV-ITRs. The high transduction efficiency, large cloning capacity, and high titer of the HD, combined with the site-specific integration machinery provided by AAV-derived components, make the Ad/AAV hybrid viruses a promising vehicle for gene therapy.

Recchia, Alessandra; Parks, Robin J.; Lamartina, Stefania; Toniatti, Carlo; Pieroni, Luisa; Palombo, Fabio; Ciliberto, Gennaro; Graham, Frank L.; Cortese, Riccardo; La Monica, Nicola; Colloca, Stefano

1999-01-01

325

A Fast and Scalable Radiation Hybrid Map Construction and Integration Strategy  

PubMed Central

This paper describes a fast and scalable strategy for constructing a radiation hybrid (RH) map from data on different RH panels. The maps on each panel are then integrated to produce a single RH map for the genome. Recurring problems in using maps from several sources are that the maps use different markers, the maps do not place the overlapping markers in same order, and the objective functions for map quality are incomparable. We use methods from combinatorial optimization to develop a strategy that addresses these issues. We show that by the standard objective functions of obligate chromosome breaks and maximum likelihood, software for the traveling salesman problem produces RH maps with better quality much more quickly than using software specifically tailored for RH mapping. We use known algorithms for the longest common subsequence problem as part of our map integration strategy. We demonstrate our methods by reconstructing and integrating maps for markers typed on the Genebridge 4 (GB4) and the Stanford G3 panels publicly available from the RH database. We compare map quality of our integrated map with published maps for GB4 panel and G3 panel by considering whether markers occur in the same order on a map and in DNA sequence contigs submitted to GenBank. We find that all of the maps are inconsistent with the sequence data for at least 50% of the contigs, but our integrated maps are more consistent. The map integration strategy not only scales to multiple RH maps but also to any maps that have comparable criteria for measuring map quality. Our software improves on current technology for doing RH mapping in areas of computation time and algorithms for considering a large number of markers for mapping. The essential impediments to producing dense high-quality RH maps are data quality and panel size, not computation.

Agarwala, Richa; Applegate, David L.; Maglott, Donna; Schuler, Gregory D.; Schaffer, Alejandro A.

2000-01-01

326

Hybridization of curvilinear time-domain integral equation and time-domain optical methods for electromagnetic scattering analysis  

Microsoft Academic Search

Full-field solutions for scattering and similar problems become prohibitively expensive for electrically large bodies. Fortunately, broadly “optical” methods become accurate as larger bodies are considered. Often, however, large bodies have significant features that are not electrically large and here hybrid approaches are appropriate. We present a novel hybridization of time-domain integral equation methods with time-domain physical optics (PO). For both

S. P. Walker; Markku J. Vartiainen

1998-01-01

327

Hybrid Technique Plus Fast Frequency Sweep for the Efficient and Accurate Analysis of Substrate Integrated Waveguide Devices  

Microsoft Academic Search

In this paper, we adapt a novel mode-matching and method-of-moments hybrid technique to efficiently analyze sub- strate integrated waveguide (SIW) based devices. The hybrid tech- nique is formulated in terms of a single equivalent current. This fact is used to include the emergent modal weights, i.e., the scat- tering parameters, as unknowns of the method-of-moments system of equations. In this

Angel Belenguer; Héctor Esteban; Elena Diaz; Carmen Bachiller; Joaquin Cascon; Vicente E. Boria

2011-01-01

328

A Massively Parallel Hybrid Dusty-Gasdynamics and Kinetic Direct Simulation Monte Carlo Model for Planetary Applications  

NASA Technical Reports Server (NTRS)

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).

Combi, Michael R.

2004-01-01

329

Microsphere-integrated gelatin-siloxane hybrid scaffolds for bone tissue engineering: in vitro bioactivity & antibacterial activity  

Microsoft Academic Search

Microsphere integrated gelatin-siloxane hybrid scaffolds were successfully synthesized by using a combined sol-gel processing,\\u000a post-gelation soaking and freeze-drying process. A bone-like apatite layer was able to form in the Ca2+-containing porous hybrids upon soaking in a simulated body fluid (SBF) up to 1 day. The rate of gentamicin sulfate (GS) release\\u000a from the GS-loaded gelatin-siloxane hybrid microsphere became constant after

Lin Wang; Bing Yu; Li-ping Sun; Lei Ren; Qi-qing Zhang

2008-01-01

330

Integration of the Hybrid Adenoretroviral Vector AdLTR-luc Involves Both MoMLV Elements Flanking the Transgene  

PubMed Central

Vector delivery is still a bottleneck for gene therapy. To overcome some disadvantages of adenoviral and retroviral vectors, we developed a hybrid vector. This hybrid vector, AdLTR-luc, was created by adding two elements from Moloney murine leukemia virus (MoMLV) flanking the luciferase cDNA into an E1/E3-deleted, replication deficient serotype 5 adenovirus vector (Zheng et al., Nature Biotechnol, 2000), and demonstrated that the MoMLV element upstream of the luciferase cDNA was broken during the integration event. The purpose of the current study was to determine if the MoMLV element downstream of the luciferase cDNA was also broken when integration occurred. We used the same A5 cell clones (#10 and 11) from the earlier the paper along with restriction endonuclease digestions, plus Southern hybridization, and PCR. Southern hybridization indicated that the luciferase cDNA was intact in the cloned cells. Results from Xho I and Sal I digestions showed that integration occurred in cloned cells. Southern hybridizations after Nco I digestion suggested that there was a break in both MoMLV elements, upstream and downstream of the luciferase cDNA. After DNA digestion with Not I, hybridization analyses indicated that the MoMLV upstream element was broken during integration. Digestion of genomic DNA with either Xba I/Kpn I, Bam HI/Sac I, or Bam HI/Nco I demonstrated that the MoMLV downstream element was also broken during integration. A PCR assay was unable to amplify the junctional region between the downstream MoMLV element and the adenoviral E2B gene, consistent with a break in that element. Although AdLTR-luc integration is atypical (Zheng et al., Nature Biotechnol, 2000), the present results suggest that both MoMLV elements have important roles in this event.

Zheng, Changyu; Baum, Bruce J.

2014-01-01

331

Automatic on-chip RNA-DNA hybridization assay with integrated phase change microvalves  

NASA Astrophysics Data System (ADS)

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 valves and thin film heaters were used to electrothermally actuate microvalves. Light absorption measured by a photodetector to determine the concentrations of the samples. The automatic control of the complete assay was implemented by a self-coded LabVIEW program. To examine the performance of this chip, Salmonella was used as a sample pathogen. Significantly, reduction in reagent/sample consumption (up to 20 folds) was achieved by this on-chip assay, compared with using the commercial test kit following the same protocol in conventional labs. The experimental results show that the quantitative detection can be obtained in approximately 26 min, and the detection limit is as low as 103 CFU ml-1. This RNA-DNA hybridization assay microfluidic chip shows an excellent potential in the development of a portable device for point-of-testing applications.

Weng, Xuan; Jiang, Hai; Wang, Junsheng; Chen, Shu; Cao, Honghe; Li, Dongqing

2012-07-01

332

Integrated genome and transcriptome sequencing identifies a novel form of hybrid and aggressive prostate cancer.  

PubMed

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

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

333

Electrocoagulation-integrated hybrid membrane processes for the treatment of tannery wastewater.  

PubMed

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

Keerthi; Vinduja, V; Balasubramanian, N

2013-10-01

334

Large arrays of spatial light modulators hybridized to silicon integrated circuits  

NASA Astrophysics Data System (ADS)

Large, high-frame-rate spatial light modulators are key components required for the realization of real-time optical processors. We report a 128 \\times 128 array of GaAs-based optical modulators that we hybridized to a Si integrated circuit by using In bump bonds to form a spatial light modulator. These optical modulators are composed of a series of quantum wells within an asymmetric Fabry-Perot cavity to control the optical properties. The resulting 128 \\times 128 element array operates in an intensity-only reflection mode at greater than 100,000 frames per second. This array interfaces to a 486-based personal computer through a standard industry standard architecture bus.

Worchesky, T. L.; Ritter, K. J.; Martin, R.; Lane, B.

1996-03-01

335

A Hybrid GNSS Integrity Design Leveraging a Priori Signal Noise Characteristics  

NASA Astrophysics Data System (ADS)

The objective of this paper is to explore a hybrid Global Navigation Satellite System (GNSS) architecture that efficiently meets the stringent needs of safety of life systems. An architecture is proposed that allocates error bounding and alerting functionality between the space, ground and user segments based on refining the assumptions of the leading-order fault free error sources expected in the near future from developing GNSS technologies. By revisiting the first principles used to derive standard RAIM fault detection, a modified detection algorithm is developed to more accurately accommodate these new fault-free error distributions while supporting timely user alerts. The results of the analysis and simulation indicate that this optimized receiver algorithm and associated architecture can provide significant development and operational benefit for navigation users requiring high levels of integrity.

Dilellio, James

336

Simulation of solar-powered ammonia-water integrated hybrid cooling system  

SciTech Connect

a number of solar-operated air-conditioning systems based on the H{sub 2}O-LiBr absorption chiller were built, installed, and monitored. A systematic study at the University of Colorado has been published. This paper presents a simple cost-benefit analysis of the conventional vapor compression system (VCS), the vapor absorption system (VAS), and the integrated hybrid system (IHS). The cost of energy input to the VAS and the IHS were compared with the energy cost of the VCS that these solar-powered systems replace. It was found that cost savings can be realized with solar-powered systems, only after a critical overall solar fraction is exceeded. Typically, this value was about 0.7 for a VAS and about 0.12 for a IHS. These cost-benefit results provided the motivation for a more detailed study of the IHS. There has also been other efforts in this direction.

Chinnappa, J.C.V. (James Cook Univ., Townsville 4811 (AU)); Wijeysundera, N.E. (Dept. of Mechanical and Production Engineering, National Univ. of Singapore (SG))

1992-05-01

337

Image restoration of hybrid time delay and integration camera system with residual motion  

NASA Astrophysics Data System (ADS)

In this paper, we present a hybrid system for time delay and integration (TDI) image restoration. Images are degraded by residual motion, which distorts and blurs the TDI images during exposures and excludes the along-track scanning motion. The motion trajectory is estimated from the image sequence captured by an auxiliary high-speed camera. In order to make the estimated results less sensitive to the imaging conditions and noise, a new method based on cross-correlation is introduced for motion estimation. Then geometric distortion of the TDI image is removed by choosing the correct blurred block according to the central of the corresponding motion trajectory and the final image is restored row by row with the Richardson-Lucy algorithm. Simulated and experimental results are given to prove the effectiveness of our system.

Zheng, Zhenzhen; Wu, Jiagu; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting

2011-06-01

338

MC21 v.6.0 - A Continuous-Energy Monte Carlo Particle Transport Code with Integrated Reactor Feedback Capabilities  

NASA Astrophysics Data System (ADS)

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.

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

339

New integrated Monte Carlo code for the simulation of high-resolution scanning electron microscopy images for metrology in microlithography  

NASA Astrophysics Data System (ADS)

A new Monte Carlo code is presented that includes among others definition of arbitrary geometries with sub-nanometer resolution, high performance parallel computing capabilities, trapped charge, electric field calculation, electron tracking in electrostatic field, and calculation of 3D dose distributions. These functionalities are efficiently implemented thanks to the coupling of the Monte Carlo simulator with a TCAD environment. Applications shown are the synthesis of SEM linescans and images that focus on the evaluation of the impact of proximity effects and self charging on the quantitative extraction of critical dimensions in dense photoresist structures.

Ilgüsatiroglu, Emre; Illarionov, Alexey Yu.; Ciappa, Mauro; Pfäffli, Paul; Bomholt, Lars

2014-04-01

340

Novel Hybrid of LS-SVM and Kalman Filter for GPS/INS Integration  

NASA Astrophysics Data System (ADS)

Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) technologies can overcome the drawbacks of the individual systems. One of the advantages is that the integrated solution can provide continuous navigation capability even during GPS outages. However, bridging the GPS outages is still a challenge when Micro-Electro-Mechanical System (MEMS) inertial sensors are used. Methods being currently explored by the research community include applying vehicle motion constraints, optimal smoother, and artificial intelligence (AI) techniques. In the research area of AI, the neural network (NN) approach has been extensively utilised up to the present. In an NN-based integrated system, a Kalman filter (KF) estimates position, velocity and attitude errors, as well as the inertial sensor errors, to output navigation solutions while GPS signals are available. At the same time, an NN is trained to map the vehicle dynamics with corresponding KF states, and to correct INS measurements when GPS measurements are unavailable. To achieve good performance it is critical to select suitable quality and an optimal number of samples for the NN. This is sometimes too rigorous a requirement which limits real world application of NN-based methods.The support vector machine (SVM) approach is based on the structural risk minimisation principle, instead of the minimised empirical error principle that is commonly implemented in an NN. The SVM can avoid local minimisation and over-fitting problems in an NN, and therefore potentially can achieve a higher level of global performance. This paper focuses on the least squares support vector machine (LS-SVM), which can solve highly nonlinear and noisy black-box modelling problems. This paper explores the application of the LS-SVM to aid the GPS/INS integrated system, especially during GPS outages. The paper describes the principles of the LS-SVM and of the KF hybrid method, and introduces the LS-SVM regression algorithm. Field test data is processed to evaluate the performance of the proposed approach.

Xu, Zhenkai; Li, Yong; Rizos, Chris; Xu, Xiaosu

341

Toward an optimum design of NRD-guide and microstrip-line transition for hybrid-integration technology  

Microsoft Academic Search

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

Abdallah Bacha; K. Wu

1998-01-01

342

Film-level hybrid integration of AlGaAs laser diode with glass waveguide on Si substrate  

Microsoft Academic Search

A ridge-waveguide AlGaAs laser diode (LD) was integrated with a SiO2-Ta2O5 embedded waveguide on a Si substrate by using a film-level hybrid integration technique of semiconductor epitaxial film. CW operation of the LD was achieved at room temperature. The LD-waveguide butt-coupling loss was 9 dB, and the loss due to misalignment was estimated at 3 dB, which corresponds to a

Masahiro Yanagisawa; Hiroshi Terui; Keizou Shuto; Tetsuo Miya; Morio Kobayashi

1992-01-01

343

Highly efficient polarization-independent grating coupler used in silica-based hybrid photodetector integration  

NASA Astrophysics Data System (ADS)

A highly efficient polarization-independent output grating coupler was optimized and designed based on silicon-on-insulator used for silica-based hybrid photodetector integration in an arrayed waveguide grating demodulation-integrated microsystem. The finite-difference time-domain (FDTD) method optimizes coupling efficiency by enabling the design of the grating period, duty cycle, etch depth, grating length, and polarization-dependent loss (PDL). The output coupling efficiencies of both the transverse electric (TE) and transverse magnetic (TM) modes are higher than 60% at 1517 to 1605 nm and ˜67% at around 1550 nm. The designed grating exhibits the desired property at the 3-dB bandwidth of 200 nm from 1450 to 1650 nm and a PDL <0.5 dB of 110 nm from 1513 to 1623 nm. The power absorption efficiency at 1550 nm for TE and TM modes reaches 78% and 70%, respectively. Both the power absorption efficiency of TE mode and that of TM mode are over 70% in a broad band of 1491 to 1550 nm.

Li, Hongqiang; Liu, Yu; Zhang, Meiling; Zhou, Wenqian; Zhang, Cheng; Li, Enbang; Miao, Changyun; Tang, Chunxiao

2014-05-01

344

40-Gb/s All-Optical Processing Systems Using Hybrid Photonic Integration Technology  

NASA Astrophysics Data System (ADS)

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.

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

345

A family of time-staggered schemes for integrating hybrid DPD models for polymers: Algorithms and applications  

Microsoft Academic Search

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

Vasileios Symeonidis; George Em. Karniadakis

2006-01-01

346

Monte Carlo analysis of a time-dependent neutron and secondary gamma-ray integral experiment on a thick concrete and steel shield  

NASA Astrophysics Data System (ADS)

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.

Cramer, S. N.; Roussin, R. W.

1981-11-01

347

Effect of surface corrugation on low temperature phases of adsorbed (p-H2)7: A quantum path integral Monte Carlo study  

NASA Astrophysics Data System (ADS)

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.

Cruz, Anthony; López, Gustavo E.

2014-04-01

348

Epitaxial growth of semimetallic hybrid substrate systems for low temperature optoelectronic integration of nitrides on silicon  

NASA Astrophysics Data System (ADS)

With increasing device integration and miniaturization, it is desirable to grow Al-Ga-N optoelectronic devices on inexpensive, large size Si wafers. The latter enables seamless integration of optical components with conventional electronics. However, Si has large lattice and thermal expansion mismatches with group-III nitrides, and absorbs visible and UV light emitted by active nitride layers. To circumvent these difficulties, unique hybrid substrates were developed based on HfxZr1-xB2(0001) buffered Si(111) including on-axis and miscut geometries. The work described in this dissertation focuses on epitaxial synthesis, characterization, and theoretical description of strain, thermoelastic behavior, and electronic structure of thick ZrB2 films and associated heterostructures including Si/ZrB2/HfxZr1-xB2, Si/ZrB 2/HfB2 and Si/HfxZr1-xB2. Optical quality ZrB2 films up to 500 nm thick were obtained via reactions of carefully tuned Zr(BH4)/H2 admixtures using gas source molecular beam epitaxy (GS-MBE). A residual tensile strain persisted in these films, independent of thickness, and it vanished at the growth temperature of 900°C. Comparison of the lattice mismatch between sapphire (Al2O3), silicon carbide (SiC), and bulk ZrB 2 substrates with GaN films over 20-900°C illustrated superior structural and thermal characteristics of the boride templates. Measurements and density functional theory (DFT) simulations of the boride dielectric function and reflectivity indicated metallic Drude behavior across the IR range. At higher energies (2-7 eV) additional spectral features were identified to be interband transitions. The ZrB2 films were used as strain-compensating buffers to fabricate HfxZr1-xB2 including HfB2 . Ellipsometry indicated that the band structure and reflectivity evolved smoothly from ZrB2 to HfB2, paving the way for the fabrication of optimized hybrid substrates, enabling large scale nitride integration with Si technologies via simultaneous optical and strain engineering. The Hf xZr1-xB2/Si technology was utilized to grow Al xGa1-xN via displacement reactions of D2GaN 3 vapors and Al atoms at unprecedented low temperatures (650-700°C), compatible with Si processing. The films exhibited strong cathodoluminescence with narrow peak widths comparable to those observed in MOCVD samples grown at 1100°C. The formation of GaN was investigated theoretically using first principle simulations.

An, Yu Jing

349

Advanced Hybrid Spacesuit Concept Featuring Integrated Open Loop and Closed Loop Ventilation Systems  

NASA Technical Reports Server (NTRS)

A document discusses the design and prototype of an advanced spacesuit concept that integrates the capability to function seamlessly with multiple ventilation system approaches. Traditionally, spacesuits are designed to operate both dependently and independently of a host vehicle environment control and life support system (ECLSS). Spacesuits that operate independent of vehicle-provided ECLSS services must do so with equipment selfcontained within or on the spacesuit. Suits that are dependent on vehicle-provided consumables must remain physically connected to and integrated with the vehicle to operate properly. This innovation is the design and prototype of a hybrid spacesuit approach that configures the spacesuit to seamlessly interface and integrate with either type of vehicular systems, while still maintaining the ability to function completely independent of the vehicle. An existing Advanced Crew Escape Suit (ACES) was utilized as the platform from which to develop the innovation. The ACES was retrofitted with selected components and one-off items to achieve the objective. The ventilation system concept was developed and prototyped/retrofitted to an existing ACES. Components were selected to provide suit connectors, hoses/umbilicals, internal breathing system ducting/ conduits, etc. The concept utilizes a lowpressure- drop, high-flow ventilation system that serves as a conduit from the vehicle supply into the suit, up through a neck seal, into the breathing helmet cavity, back down through the neck seal, out of the suit, and returned to the vehicle. The concept also utilizes a modified demand-based breathing system configured to function seamlessly with the low-pressure-drop closed-loop ventilation system.

Daniel, Brian A.; Fitzpatrick, Garret R.; Gohmert, Dustin M.; Ybarra, Rick M.; Dub, Mark O.

2013-01-01

350

Cultivating Curiosity: Integrating Hybrid Teaching in Courses in Human Behavior in the Social Environment  

ERIC Educational Resources Information Center

This study illustrates an experience of implementing a hybrid model for teaching human behavior in the social environment in an urban university setting. Developing a hybrid model in a BSW program arose out of a desire to reach students in a different way. Designed to promote curiosity and active learning, this particular hybrid model has students…

Rodriguez-Keyes, Elizabeth; Schneider, Dana A.

2013-01-01

351

Design and construction of a VHGT-attached WDM-type triplex transceiver module using polymer PLC hybrid integration technology  

NASA Astrophysics Data System (ADS)

We report about design and construction of the bidirectional transceiver TRx module for subscriber part of the passive optical network PON for a fiber to the home FTTH topology. The TRx module consists of a epoxy novolak resin polymer planar lightwave circuit (PLC) hybrid integration technology with volume holographic grating triplex filter VHGT, surface-illuminated photodetectors and spot-size converted Fabry-Pérot laser diode in SMD package. The hybrid PLC has composed from a two parts-polymer optical waveguide including VHGT filter section and a optoelectronic microwave section. The both parts are placed on the composite substrate.

Jerábek, Vitezslav; Hüttel, Ivan; Prajzler, Václav; Busek, K.; Seliger, P.

2008-11-01

352

Diffusion-controlled evolution of core-shell nanowire arrays into integrated hybrid nanotube arrays for Li-ion batteries  

NASA Astrophysics Data System (ADS)

Controlled integration of multiple semiconducting oxides into each single unit of ordered nanotube arrays is highly desired in scientific research for the realization of more attractive applications. We herein report a diffusion-controlled solid-solid route to evolve simplex Co(CO3)0.5(OH)0.11H2O@TiO2 core-shell nanowire arrays (NWs) into CoO-CoTiO3 integrated hybrid nanotube arrays (NTs) with preserved morphology. During the evolution procedure, the decomposition of Co(CO3)0.5(OH)0.11H2O NWs into chains of CoCO3 nanoparticles initiates the diffusion process and promotes the interfacial solid-solid diffusion reaction even at a low temperature of 450 °C. The resulting CoO-CoTiO3 NTs possess well-defined sealed tubular geometries and a special ``inner-outer'' hybrid nature, which is suitable for application in Li-ion batteries (LIBs). As a proof-of-concept demonstration of the functions of such hybrid NTs in LIBs, CoO-CoTiO3 NTs are directly tested as LIB anodes, exhibiting both a high capacity (~600 mA h g-1 still remaining after 250 continuous cycles) and a much better cycling performance (no capacity fading within 250 total cycles) than CoO NWs. Our work presents not only a diffusion route for the formation of integrated hybrid NTs but also a new concept that can be employed as a general strategy to fabricate other oxide-based hybrid NTs for energy storage devices.Controlled integration of multiple semiconducting oxides into each single unit of ordered nanotube arrays is highly desired in scientific research for the realization of more attractive applications. We herein report a diffusion-controlled solid-solid route to evolve simplex Co(CO3)0.5(OH)0.11H2O@TiO2 core-shell nanowire arrays (NWs) into CoO-CoTiO3 integrated hybrid nanotube arrays (NTs) with preserved morphology. During the evolution procedure, the decomposition of Co(CO3)0.5(OH)0.11H2O NWs into chains of CoCO3 nanoparticles initiates the diffusion process and promotes the interfacial solid-solid diffusion reaction even at a low temperature of 450 °C. The resulting CoO-CoTiO3 NTs possess well-defined sealed tubular geometries and a special ``inner-outer'' hybrid nature, which is suitable for application in Li-ion batteries (LIBs). As a proof-of-concept demonstration of the functions of such hybrid NTs in LIBs, CoO-CoTiO3 NTs are directly tested as LIB anodes, exhibiting both a high capacity (~600 mA h g-1 still remaining after 250 continuous cycles) and a much better cycling performance (no capacity fading within 250 total cycles) than CoO NWs. Our work presents not only a diffusion route for the formation of integrated hybrid NTs but also a new concept that can be employed as a general strategy to fabricate other oxide-based hybrid NTs for energy storage devices. Electronic supplementary information (ESI) available: SEM images of Co(CO3)0.5(OH)0.11H2O NWs, SEM/TEM images of CoO-CoTiO3 hybrid nanotubes and the calculation of CoTiO3 theoretical capacity. See DOI: 10.1039/c3nr01786a

Jiang, Jian; Luo, Jingshan; Zhu, Jianhui; Huang, Xintang; Liu, Jinping; Yu, Ting

2013-08-01

353

Bio-hybrid integrated system for wide-spectrum solar energy harvesting  

NASA Astrophysics Data System (ADS)

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.

Martin, Kathleen; Erdman, Matthew; Quintana, Hope; Shelnutt, John; Nogan, John; Swartzentruber, B.; Martinez, Julio; Lavrova, Olga; Busani, Tito

2014-03-01

354

Femtosecond laser fabrication of hybrid micro-optical elements and their integration on the fiber tip  

NASA Astrophysics Data System (ADS)

Femtosecond laser photo-polymerization of zirconium-silicon based sol-gel photopolymer SZ2080 is used to fabricate micro-optical elements with a single and hybrid optical functions. We demonstrate photo-polymerization of the solid immersion and Fresnel lenses. Gratings can be added onto the surface of lenses. The effective refractive index of polymerized structures can be controlled via the volume fraction of polymer. We used woodpile structure with volume fraction of 0.65-0.8. Tailoring of dispersion properties of micro-optical elements by changing filling ratio of polymer are discussed. Direct write approach is used to form such structures on a cover glass and on the tip of an optical fiber. Close matching of refractive indices between the polymer and substrate in visible and near infra red spectral regions (nSZ2080 = 1.504, nglass = 1.52) is favorable for such integration. The surface roughness of laser-polymerized resits was ~30 nm (min-max value), which is acceptable for optical applications in the visible range. For the bulk micro-optical elements the efficiency of 3D laser polymerization is increased by a factor ~ (2 - 4) × 102 times (depends on the design) by the shell-formation polymerization: (i) contour scanning for definition of shell-surface, (ii) development for removal of nonfunctional resist, and (iii) UV exposure for the final volumetric polymerization of an enclosed volume.

Malinauskas, Mangirdas; Gilbergs, Holger; Zukauskas, Albertas; Belazaras, Kastytis; Purlys, Vytautas; Rutkauskas, Marius; Bickauskaite, Gabija; Momot, Andrej; Paipulas, Domas; Gadonas, Roaldas; Juodkazis, Saulius; Piskarskas, Algis

2010-04-01

355

Integration and optimization of the gas removal system for hybrid-cycle OTEC power plants  

SciTech Connect

A preliminary design of the noncondensible gas removal system for a 10 mWe, land-based hybrid-cycle OTEC power plant has been developed and is presented herein. This gas removal system is very different from that used for conventional power plants because of the substantially larger and continuous noncondensible gas flow rates and lower condenser pressure levels which predicate the need for higher-efficiency components. Previous OTEC studies discussed the need for multiple high-efficiency compressors with intercoolers; however, no previous design effort was devoted to the details of the intercoolers, integration and optimization of the intercoolers with the compressors, and the practical design constraints and feasibility issues of these components. The resulting gas removal system design uses centrifugal (radial) compressors with matrix-type crossflow aluminum heat exchangers as intercoolers. Once-through boiling of ammonia is used as the heat sink for the cooling and condensing of the steam-gas mixture. A computerized calculation method was developed for the performance analysis and subsystem optimization. For a specific number of compressor units and the stream arrangement, the method is used to calculate the dimensions, speeds, power requirements, and costs of all the components.

Rabas, T.J.; Panchal, C.B.; Stevens, H.C. (Energy Systems Div., Argonne National Lab., Argonne, IL (US))

1990-02-01

356

Integrated Plasma Simulation of Ion Cyclotron and Lower Hybrid Range of Frequencies Actuators in Tokamaks  

NASA Astrophysics Data System (ADS)

Recent upgrades to the ion cyclotron RF (ICRF) and lower hybrid RF (LHRF) components of the Integrated Plasma Simulator [1] have made it possible to simulate LH current drive in the presence of ICRF minority heating and mode conversion electron heating. The background plasma is evolved in these simulations using the TSC transport code [2]. The driven LH current density profiles are computed using advanced ray tracing (GENRAY) and Fokker Planck (CQL3D) [3] components and predictions from GENRAY/CQL3D are compared with a ``reduced'' model for LHCD (the LSC [4] code). The ICRF TORIC solver is used for minority heating with a simplified (bi-Maxwellian) model for the non-thermal ion tail. Simulation results will be presented for LHCD in the presence of ICRF heating in Alcator C-Mod. [4pt] [1] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008).[0pt] [2] S. C. Jardin et al, J. Comp. Phys. 66, 481 (1986).[0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Meeting on Simulation and Modeling of Therm. Plasmas, Montreal, Canada (1992).[0pt] [4] D. Ignat et al, Nucl. Fus. 34, 837 (1994).[0pt] [5] M. Brambilla, Plasma Phys. and Cont. Fusion 41,1 (1999).

Bonoli, P. T.; Shiraiwa, S.; Wright, J. C.; Harvey, R. W.; Batchelor, D. B.; Berry, L. A.; Chen, Jin; Poli, F.; Kessel, C. E.; Jardin, S. C.

2012-10-01

357

Hybrid Finite Element-Fast Spectral Domain Multilayer Boundary Integral Modeling of Doubly Periodic Structures  

SciTech Connect

Hybrid finite element (FE)--boundary integral (BI) analysis of infinite periodic arrays is extended to include planar multilayered Green's functions. In this manner, a portion of the volumetric dielectric region can be modeled via the finite element method whereas uniform multilayered regions can be modeled using a multilayered Green's function. As such, thick uniform substrates can be modeled without loss of efficiency and accuracy. The multilayered Green's function is analytically computed in the spectral domain and the resulting BI matrix-vector products are evaluated via the fast spectral domain algorithm (FSDA). As a result, the computational cost of the matrix-vector products is kept at O(N). Furthermore, the number of Floquet modes in the expansion are kept very few by placing the BI surfaces within the computational unit cell. Examples of frequency selective surface (FSS) arrays are analyzed with this method to demonstrate the accuracy and capability of the approach. One example involves complicated multilayered substrates above and below an inhomogeneous filter element and the other is an optical ring-slot array on a substrate several hundred wavelengths in thickness. Comparisons with measurements are included.

T.F. Eibert; J.L. Volakis; Y.E. Erdemli

2002-03-03

358

A high-density integrated genetic linkage and radiation hybrid map of the laboratory rat.  

PubMed

The laboratory rat (Rattus norvegicus) is a key animal model for biomedical research. However, the genetic infrastructure required for connecting phenotype and genotype in the rat is currently incomplete. Here, we report the construction and integration of two genomic maps: a dense genetic linkage map of the rat and the first radiation hybrid (RH) map of the rat. The genetic map was constructed in two F2 intercrosses (SHRSP x BN and FHH x ACI), containing a total of 4736 simple sequence length polymorphism (SSLP) markers. Allele sizes for 4328 of the genetic markers were characterized in 48 of the most commonly used inbred strains. The RH map is a lod >/= 3 framework map, including 983 SSLPs, thereby allowing integration with markers on various genetic maps and with markers mapped on the RH panel. Together, the maps provide an integrated reference to >3000 genes and ESTs and >8500 genetic markers (5211 of our SSLPs and >3500 SSLPs developed by other groups). [Bihoreau et al. (1997); James and Tanigami, RHdb (http:www.ebi.ac.uk/RHdb/index.html); Wilder (http://www.nih.gov/niams/scientific/ratgbase); Serikawa et al. (1992); RATMAP server (http://ratmap.gen.gu.se)] RH maps (v. 2.0) have been posted on our web sites at http://goliath.ifrc.mcw.edu/LGR/index.html or http://curatools.curagen.com/ratmap. Both web sites provide an RH mapping server where investigators can localize their own RH vectors relative to this map. The raw data have been deposited in the RHdb database. Taken together, these maps provide the basic tools for rat genomics. The RH map provides the means to rapidly localize genetic markers, genes, and ESTs within the rat genome. These maps provide the basic tools for rat genomics. They will facilitate studies of multifactorial disease and functional genomics, allow construction of physical maps, and provide a scaffold for both directed and large-scale sequencing efforts and comparative genomics in this important experimental organism. PMID:10400928

Steen, R G; Kwitek-Black, A E; Glenn, C; Gullings-Handley, J; Van Etten, W; Atkinson, O S; Appel, D; Twigger, S; Muir, M; Mull, T; Granados, M; Kissebah, M; Russo, K; Crane, R; Popp, M; Peden, M; Matise, T; Brown, D M; Lu, J; Kingsmore, S; Tonellato, P J; Rozen, S; Slonim, D; Young, P; Jacob, H J

1999-06-01

359

Diffusion-controlled evolution of core-shell nanowire arrays into integrated hybrid nanotube arrays for Li-ion batteries.  

PubMed

Controlled integration of multiple semiconducting oxides into each single unit of ordered nanotube arrays is highly desired in scientific research for the realization of more attractive applications. We herein report a diffusion-controlled solid-solid route to evolve simplex Co(CO3)0.5(OH)0.11H2O@TiO2 core-shell nanowire arrays (NWs) into CoO-CoTiO3 integrated hybrid nanotube arrays (NTs) with preserved morphology. During the evolution procedure, the decomposition of Co(CO3)0.5(OH)0.11H2O NWs into chains of CoCO3 nanoparticles initiates the diffusion process and promotes the interfacial solid-solid diffusion reaction even at a low temperature of 450 °C. The resulting CoO-CoTiO3 NTs possess well-defined sealed tubular geometries and a special "inner-outer" hybrid nature, which is suitable for application in Li-ion batteries (LIBs). As a proof-of-concept demonstration of the functions of such hybrid NTs in LIBs, CoO-CoTiO3 NTs are directly tested as LIB anodes, exhibiting both a high capacity (~600 mA h g(-1) still remaining after 250 continuous cycles) and a much better cycling performance (no capacity fading within 250 total cycles) than CoO NWs. Our work presents not only a diffusion route for the formation of integrated hybrid NTs but also a new concept that can be employed as a general strategy to fabricate other oxide-based hybrid NTs for energy storage devices. PMID:23884214

Jiang, Jian; Luo, Jingshan; Zhu, Jianhui; Huang, Xintang; Liu, Jinping; Yu, Ting

2013-09-01

360

Monte Carlo evaluation of the equilibrium isotope effects using the Takahashi-Imada factorization of the Feynman path integral  

NASA Astrophysics Data System (ADS)

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; Vaní?ek, Ji?í

2013-11-01

361

Modeling and control of a seven-phase claw-pole integrated starter alternator for micro-hybrid automotive applications  

Microsoft Academic Search

This paper deals with the modeling and the control of a new high power 12 V integrated starter alternator (ISA). This system is used to bring micro-hybrid functions to standard internal combustion engine (ICE) vehicles. The drive is composed of a seven-phase synchronous claw-pole machine with separate excitation, supplied with a seven-leg Voltage Source Inverter (VSI) designed for low voltage

A. Bruyere; E. Semail; A. Bouscayrol; F. Locment; J. M. Dubus; J. C. Mipo

2008-01-01

362

Integrated forward osmosis–membrane distillation (FO–MD) hybrid system for the concentration of protein solutions  

Microsoft Academic Search

For the first time, an integrated forward osmosis–membrane distillation (FO–MD) hybrid system has been demonstrated for the concentration of protein solutions, specifically a bovine serum albumin (BSA) solution. A hydrophilic polybenzimidazole (PBI) nanofiltration hollow fiber membrane and a hydrophobic polyvinylidene fluoride-polytetrafluoroethylene (PVDF-PTFE) hollow fiber membrane were fabricated and employed in the FO and MD processes, respectively. A concentrated NaCl solution

Kai Yu Wang; May May Teoh; Adrian Nugroho; Tai-Shung Chung

2011-01-01

363

Fabrication of a TFF-Attached WDM-Type Triplex Transceiver Module Using Silica PLC Hybrid Integration Technology  

Microsoft Academic Search

An optical triplex transceiver (TRx) module, which consists of thin-film filter (TFF)-attached wavelength-division multiplexer (WDM) and photodiode (PD) carriers, has been fabricated using a silica planar lightwave circuit (PLC) hybrid integration technology. Two types of TFFs were attached to a diced sidewall of a silica-terraced PLC platform to realize the TFF-attached WDM. The PD carriers with a 45deg mirror, on

Young-Tak Han; Yoon-Jung Park; Sang-Ho Park; Jang-Uk Shin; Chul-Wook Lee; Hyunsung Ko; Yongsoon Baek; Chul-Hee Park; Yoon-Koo Kwon; Wol-Yon Hwang; Kwang-Ryong Oh; Heekyung Sung

2006-01-01

364

Design and Analysis of a Hybrid Feed Antenna for a Flux-Flow Oscillator Integrated 460 GHz SIS Receiver  

Microsoft Academic Search

We have designed a 460 GHz FFO-driven integrated SIS receiver in which the sig- nal is fed via a quasi-optical hybrid antenna feeding system. Since in such quasi-optical SIS receivers the contribution of the quasi-optics to the overall receiver noise is consid- erable, it is important to be able to analyze the antenna efficiency in order to optimize its coupling

M.-H. Chung; M. Salez

2000-01-01

365

180-degree substrate integrated waveguide hybrid and its application to broadband millimeter-wave single balanced mixer design  

Microsoft Academic Search

This paper presents a broadband millimetre-wave single balanced diode mixer that makes use of an innovative substrate integrated waveguide (SIW) based 180-degree hybrid, fabricated with conventional printed circuit board (PCB) technique. The proposed mixer has advantages over other previously reported millimetre-wave mixer structures judging from a series of aspects such as cost, ease of fabrication, planar construction and broadband performance.

Zhen-Yu Zhang; Ke Wu; Ying Rao Wei

2010-01-01

366

Coupled-slotline-hybrid sampling mixer integrated with step-recovery-diode pulse generator for UWB applications  

Microsoft Academic Search

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

Jeongwoo Han; Cam Nguyen

2005-01-01

367

Prediction of qualitative outcome of oligonucleotide microarray hybridization by measurement of RNA integrity using the 2100 Bioanalyzer™ capillary electrophoresis system  

Microsoft Academic Search

RNA quality is critical to achieve valid results in microarray experiments and to save resources. The RNA integrity number\\u000a (RIN) can be measured with minimal sample consumption by microfluidics-based capillary electrophoresis. To determine whether\\u000a RIN can predict the qualitative outcome of microarray hybridization, we measured RIN in total RNA samples from 484 different\\u000a experiments by the 2100 Bioanalyzer system and

Philipp Kiewe; Saskia Gueller; Martina Komor; Andrea Stroux; Eckhard Thiel; Wolf-Karsten Hofmann

2009-01-01

368

A segmented hybrid photon detector with integrated auto-triggering front-end electronics for a PET scanner  

NASA Astrophysics Data System (ADS)

We describe the design, fabrication and test results of a segmented hybrid photon detector with integrated auto-triggering front-end electronics. Both the photodetector and its VLSI readout electronics are custom designed and have been tailored to the requirements of a recently proposed novel geometrical concept of a positron emission tomograph. Emphasis is put on the PET-specific features of the device. The detector has been fabricated in the photocathode facility at CERN.

Chesi, E.; Braem, A.; Joram, C.; Mathot, S.; Séguinot, J.; Weilhammer, P.; Ciocia, F.; De Leo, R.; Nappi, E.; Vilardi, I.; Argentieri, A.; Corsi, F.; Dragone, A.; Pasqua, D.

2006-08-01

369

Hybrid integrated plasmonic-photonic waveguides for on-chip localized surface plasmon resonance (LSPR) sensing and spectroscopy.  

PubMed

We experimentally demonstrate efficient extinction spectroscopy of single plasmonic gold nanorods with exquisite fidelity (SNR > 20dB) and high efficiency light coupling (e. g., 9.7%) to individual plasmonic nanoparticles in an integrated platform. We demonstrate chip-scale integration of lithographically defined plasmonic nanoparticles on silicon nitride (Si3N4) ridge waveguides for on-chip localized surface plasmon resonance (LSPR) sensing. The integration of this hybrid plasmonic-photonic platform with microfluidic sample delivery system is also discussed for on-chip LSPR sensing of D-glucose with a large sensitivity of ? 250 nm/RIU. The proposed architecture provides an efficient means of interrogating individual plasmonic nanoparticles with large SNR in an integrated alignment-insensitive platform, suitable for high-density on-chip sensing and spectroscopy applications. PMID:24514803

Chamanzar, Maysamreza; Xia, Zhixuan; Yegnanarayanan, Siva; Adibi, Ali

2013-12-30

370

MÖNCH, a small pitch, integrating hybrid pixel detector for X-ray applications  

NASA Astrophysics Data System (ADS)

PSI is developing several new detector families based on charge integration and analog readout (CI) to respond to the needs of X-ray free electron lasers (XFELs), where a signal up to ~ 104 photons impinging simultaneously on a pixel make single photon counting detectors unusable. MÖNCH is a novel hybrid silicon pixel detector where CI is combined with a challengingly small pixel size of 25 × 25 ?m2. CI enables the detector to process several incoming photon simultaneously in XFEL applications. Moreover, due to the small pixel size, the charge produced by an impinging photon is often shared. In low flux experiments the analog information provided by single photons can be used either to obtain spectral information or to improve the position resolution by interpolation. Possible applications are resonant and non-resonant inelastic X-ray scattering or X-ray tomography with X-ray tubes. Two prototype ASICs were designed in UMC 110 nm technology. MÖNCH01 contains only some test cells used to assess technology performance and make basic design choices. MÖNCH02 is a fully functional, small scale prototype of 4 × 4 mm2, containing an array of 160 × 160 pixels. This array is subdivided in five blocks, each featuring a different pixel architecture. Two blocks have statically selectable preamplifier gains and target synchrotron applications. In low gain mode they should provide single photon sensitivity (at 6-12 keV) as well as a reasonable dynamic range for such a small area ( > 120 photons). In high gain they target high resolution, low flux experiments where charge sharing can be exploited to reach ?m resolution. Three other architectures address possible uses at XFELs and implement automatic switching between two gains to increase the dynamic range, as well as input overvoltage control. The paper presents the MÖNCH project and first results obtained with the MÖNCH02 prototype.

Dinapoli, R.; Bergamaschi, A.; Cartier, S.; Greiffenberg, D.; Johnson, I.; Jungmann, J. H.; Mezza, D.; Mozzanica, A.; Schmitt, B.; Shi, X.; Tinti, G.

2014-05-01

371

Hybrid materials science: a promised land for the integrative design of multifunctional materials.  

PubMed

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

Nicole, Lionel; Laberty-Robert, Christel; Rozes, Laurence; Sanchez, Clément

2014-06-21

372

Hybrid materials science: a promised land for the integrative design of multifunctional materials  

NASA Astrophysics Data System (ADS)

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.

Nicole, Lionel; Laberty-Robert, Christel; Rozes, Laurence; Sanchez, Clément

2014-05-01

373

Hybrid polymer electrolyte membrane for silicon-based micro fuel cells integration  

Microsoft Academic Search

A novel approach for a hybrid polymer electrolyte membrane compatible with silicon-based fuel cells is proposed in this study. The membrane consists of a polymer matrix of polydimethylsiloxane (PDMS) filled with a proton-conducting polymer. The fabrication steps of the hybrid membrane as well as its electrochemical characterization are explained in detail. The obtained proton conductivities demonstrate the validity of the

J. P. Esquivel; N. Sabaté; A. Tarancón; N. Torres-Herrero; D. Dávila; J. Santander; I. Gràcia; C. Cané

2009-01-01

374

Computations for various edge configurations with the hybrid Finite Element - Boundary Integral - Multilevel Fast Multipole - uniform geometrical theory of diffraction method including double diffraction  

Microsoft Academic Search

Recently, a powerful hybrid numerical method was introduced, combining the finite element boundary integral (FEBI) method and the multilevel fast multipole method (MLFMM) with the Uniform geometrical theory of diffraction (UTD), in which single and multiple reflections on flat metallic objects, combined with single diffractions on straight metallic edges, were considered. In this contribution, the hybrid FEBI-MLFMM-UTD method is extended

A. Tzoulis; T. F. Eibert

2006-01-01

375

Unsteady Annular Viscous Flows Between Oscillating Cylinders. Part II: A Hybrid Time-Integration Solution Based on Azimuthal Fourier Expansions for Configurations with Annular Backsteps  

Microsoft Academic Search

A hybrid time-integration method based on azimuthal Fourier expansions for solving the time-dependent incompressible Navier-Stokes equations has been developed in order to obtain superior computational efficiency; this will permit simultaneous time-integration of the coupled systems of equations of fluid and structural unsteady motions. The hybrid method uses highly convergent Fourier expansions in the azimuthal angular coordinate for the unsteady pressure

D. Mateescu; M. P. Païdoussis; F. Belanger

1994-01-01

376

An Improved Solution for Integrated Array Optics in Quasi-Optical mm and Submm Receivers: the Hybrid Antenna  

NASA Technical Reports Server (NTRS)

The hybrid antenna discussed here is defined as a dielectric lens-antenna as a special case of an extended hemi-spherical 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 hemi- spherical 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 4 +/- 6) % for a diffraction limited beam with sidelobes below -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.

Buttgenbach, Thomas H.

1993-01-01

377

Hybrid extended particle filter (HEPF) for integrated inertial navigation and global positioning systems  

Microsoft Academic Search

Navigation includes the integration of methodologies and systems for estimating time-varying position, velocity and attitude of moving objects. Navigation incorporating the integrated inertial navigation system (INS) and global positioning system (GPS) generally requires extensive evaluations of nonlinear equations involving double integration. Currently, integrated navigation systems are commonly implemented using the extended Kalman filter (EKF). The EKF assumes a linearized process,

Priyanka Aggarwal; Zainab Syed; Naser El-Sheimy

2009-01-01

378

An integrated model for performance simulation of hybrid wind–diesel systems  

Microsoft Academic Search

Stand-alone hybrid systems have turned into one of the most promising ways to handle the electrification requirements of numerous isolated consumers worldwide. The proposed wind–diesel–battery hybrid system consists of a micro-wind converter, a small diesel-electric generator—basically operating as a back up energy production system—and a lead-acid battery bank that stores the wind energy surplus during high wind speed periods. In

J. K. Kaldellis

2007-01-01

379

VERIFICATION OF THE SHIFT MONTE CARLO CODE  

Microsoft Academic Search

Shift is a new hybrid Monte Carlo\\/deterministic radiation transport code being developed at Oak Ridge National Laboratory. At its current stage of development, Shift includes a fully-functional parallel Monte Carlo capability for simulating eigenvalue and fixed-source multigroup transport problems. This paper focuses on recent efforts to verify Shift s Monte Carlo component using the two-dimensional and three-dimensional C5G7 NEA benchmark

Nicholas Sly; Mervin Brenden Mervin; Scott W Mosher; Thomas M Evans; G. Ivan Maldonado

2012-01-01

380

How Safe is Control Banding? Integrated Evaluation by Comparing OELs with Measurement Data and Using Monte Carlo Simulation  

Microsoft Academic Search

The present study aims to explore the protection level that can be achieved by the German con- trol banding (CB) tool Einfaches Massnahmenkonzept Gefahrstoffe, 'Easy-to-use workplace control scheme for hazardous substances'. The rationale of our integrated approach is based on the Bewertungsindex (BWI), which is the quotient of the exposure level and the occupational exposure limit (OEL), with BWI <1

MARTIN TISCHER; SUSANNE BREDENDIEK-KAMPER; ULRICH POPPEK; ROLF PACKROFF

2009-01-01

381

Optimizing efficiency of perturbative Monte Carlo method  

Microsoft Academic Search

We introduce error weighting functions into the perturbative Monte Carlo method for use with a hybrid ab initio quantum . mechanicsrmolecular mechanics QMrMM potential. The perturbative Monte Carlo approach introduced earlier provides a means to reduce the number of full SCF calculations in simulations using a QMrMM potential by evoking perturbation theory to calculate energy changes due to displacements of

Tom J. Evans; Thanh N. Truong

1998-01-01

382

A hybrid approach to survival model building using integration of clinical and molecular information in censored data.  

PubMed

In medical society, the prognostic models, which use clinicopathologic features and predict prognosis after a certain treatment, have been externally validated and used in practice. In recent years, most research has focused on high dimensional genomic data and small sample sizes. Since clinically similar but molecularly heterogeneous tumors may produce different clinical outcomes, the combination of clinical and genomic information, which may be complementary, is crucial to improve the quality of prognostic predictions. However, there is a lack of an integrating scheme for clinic-genomic models due to the P ? N problem, in particular, for a parsimonious model. We propose a methodology to build a reduced yet accurate integrative model using a hybrid approach based on the Cox regression model, which uses several dimension reduction techniques, L? penalized maximum likelihood estimation (PMLE), and resampling methods to tackle the problem. The predictive accuracy of the modeling approach is assessed by several metrics via an independent and thorough scheme to compare competing methods. In breast cancer data studies on a metastasis and death event, we show that the proposed methodology can improve prediction accuracy and build a final model with a hybrid signature that is parsimonious when integrating both types of variables. PMID:22350208

Choi, Ickwon; Kattan, Michael W; Wells, Brian J; Yu, Changhong

2012-01-01

383

Hybrid adeno-associated viral vectors utilizing transposase-mediated somatic integration for stable transgene expression in human cells.  

PubMed

Recombinant adeno-associated viral (AAV) vectors have been shown to be one of the most promising vectors for therapeutic gene delivery because they can induce efficient and long-term transduction in non-dividing cells with negligible side-effects. However, as AAV vectors mostly remain episomal, vector genomes and transgene expression are lost in dividing cells. Therefore, to stably transduce cells, we developed a novel AAV/transposase hybrid-vector. To facilitate SB-mediated transposition from the rAAV genome, we established a system in which one AAV vector contains the transposon with the gene of interest and the second vector delivers the hyperactive Sleeping Beauty (SB) transposase SB100X. Human cells were infected with the AAV-transposon vector and the transposase was provided in trans either by transient and stable plasmid transfection or by AAV vector transduction. We found that groups which received the hyperactive transposase SB100X showed significantly increased colony forming numbers indicating enhanced integration efficiencies. Furthermore, we found that transgene copy numbers in transduced cells were dose-dependent and that predominantly SB transposase-mediated transposition contributed to stabilization of the transgene. Based on a plasmid rescue strategy and a linear-amplification mediated PCR (LAM-PCR) protocol we analysed the SB100X-mediated integration profile after transposition from the AAV vector. A total of 1840 integration events were identified which revealed a close to random integration profile. In summary, we show for the first time that AAV vectors can serve as template for SB transposase mediated somatic integration. We developed the first prototype of this hybrid-vector system which with further improvements may be explored for treatment of diseases which originate from rapidly dividing cells. PMID:24116154

Zhang, Wenli; Solanki, Manish; Müther, Nadine; Ebel, Melanie; Wang, Jichang; Sun, Chuanbo; Izsvak, Zsuzsanna; Ehrhardt, Anja

2013-01-01

384

A scanning probe-based pick-and-place procedure for assembly of integrated quantum optical hybrid devices  

NASA Astrophysics Data System (ADS)

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 way, both the topography and the optical response can be monitored simultaneously before and after the assembly. The technique can be applied to arbitrary particles. Here, we focus on nanodiamonds containing single nitrogen vacancy centers, which are particularly interesting for quantum optical experiments on the single photon and single emitter level.

Schell, Andreas W.; Kewes, Günter; Schröder, Tim; Wolters, Janik; Aichele, Thomas; Benson, Oliver

2011-07-01

385

Sub-array receiver with thick-film hybrid integrated micro-package for L-band  

NASA Astrophysics Data System (ADS)

A subarray receiver used in a line array test for L-band DBF (digital beamforming) is described in this paper. The receiver consists of a RF module, an IF module and an I/Q (in-phase and quadrature) channel module. The receiver is made of thick-film hybrid integrated circuit with monolithic chip inserts and surface mount components using micro-package technology. This receiver of the radar is small in volume, light in weight, and has advantages of low cost, high performance and high reliability in comparison with conventional receiver.

Zhou, Genxiang; Zhang, Yuanjian; Sun, Qi; Li, Jingwen; Xiao, Deyuan

386

Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with Quasi-Monte Carlo integration  

SciTech Connect

This thesis presents a measurement of the top quark mass obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. The measurement uses a matrix element integration method to calculate a t{bar t} likelihood, employing a Quasi-Monte Carlo integration, which enables us to take into account effects due to finite detector angular resolution and quark mass effects. We calculate a t{bar t} likelihood as a 2-D function of the top pole mass m{sub t} and {Delta}{sub JES}, where {Delta}{sub JES} parameterizes the uncertainty in our knowledge of the jet energy scale; it is a shift applied to all jet energies in units of the jet-dependent systematic error. By introducing {Delta}{sub JES} into the likelihood, we can use the information contained in W boson decays to constrain {Delta}{sub JES} and reduce error due to this uncertainty. We use a neural network discriminant to identify events likely to be background, and apply a cut on the peak value of individual event likelihoods to reduce the effect of badly reconstructed events. This measurement uses a total of 4.3 fb{sup -1} of integrated luminosity, requiring events with a lepton, large E{sub T}, and exactly four high-energy jets in the pseudorapidity range |{eta}| < 2.0, of which at least one must be tagged as coming from a b quark. In total, we observe 738 events before and 630 events after applying the likelihood cut, and measure m{sub t} = 172.6 {+-} 0.9 (stat.) {+-} 0.7 (JES) {+-} 1.1 (syst.) GeV/c{sup 2}, or m{sub t} = 172.6 {+-} 1.6 (tot.) GeV/c{sup 2}.

Lujan, Paul Joseph; /UC, Berkeley /LBL, Berkeley

2009-12-01

387

A hybrid approach to protein folding problem integrating constraint programming with local search  

Microsoft Academic Search

Background: The protein folding problem remains one of the most challenging open problems in computational biology. Simplified models in terms of lattice structure and energy function have been proposed to ease the computational hardness of this optimization problem. Heuristic search algorithms and constraint programming are two common techniques to approach this problem. The present study introduces a novel hybrid approach

Abu Zafer M. Dayem Ullah; Kathleen Steinhöfel

2010-01-01

388

AN INTEGRATED AUTOMOTIVE ROOF MODULE CONCEPT: PLASTIC-METAL HYBRID AND POLYURETHANE COMPOSITE TECHNOLOGY  

Microsoft Academic Search

The implementation of metal stampings combined with injection molded 30% glass fiber reinforced polyamide type 6 (PA6-GF30%) for commercial passenger car and truck front end modules has grown in the automotive industry over the past five years. This patented Plastic- Metal Hybrid (PMH) design technology has proven its ability to enable the automotive original equipment manufacturer (OEM) to engage a

C. Korson; D. Stratton

389

High performance Hybrid and Monolithic Backside Thinned CMOS Imagers realized using a new integration process  

Microsoft Academic Search

Hybrid and monolithic thinned backside illuminated CMOS imagers operating at full depletion at low substrate voltages were developed. The combination of a 50 mum EPI layer with varying doping concentration and trenches to reduce crosstalk is unique. All thin wafer processing is performed on 200 mm wafers using a specially developed temporary carrier process. As a result, working imagers exhibiting

Koen De Munck; Deniz Sabuncuoglu Tezcan; Tom Borgers; Wouter Ruythooren; P. De Moor; S. Sedky; C. Toccafondi; J. Bogaerts; C. Van Hoof

2006-01-01

390

On the integration of optimal energy management and thermal management of hybrid electric vehicles  

Microsoft Academic Search

This paper proposes a supervisory control for hybrid electrical vehicle (HEV). It is based on Equivalent Consumption Minimization Strategy (ECMS) extended with a new state reflecting the thermal state of the engine. A new consumption law taking into account the losses due to low engine temperature is therefore included in the optimal control problem. The strategy is tested offline on

Julien Lescot; Antonio Sciarretta; Yann Chamaillard; Alain Charlet

2010-01-01

391

Hybrid Architecture and Integrated Routing in a Scalable Optical–Wireless Access Network  

Microsoft Academic Search

We propose a hybrid optical-wireless access network that consists of reconfigurable optical backhaul and wireless mesh networks (WMNs). The complementary characteristics of wireless and optical networks are combined to provide a broadband and ubiquitous last-mile connection. Wireless mesh routers are deployed to penetrate the vicinity of end users for a flexible and ubiquitous connection. It eliminates massive and geographically scattered

Wei-Tao Shaw; Shing-Wa Wong; Ning Cheng; Koussalya Balasubramanian; Xiaoqing Zhu; Martin Maier; Leonid G. Kazovsky

2007-01-01

392

Integrated Backup Topology Control and Routing of Obscured Traffic in Hybrid RF\\/FSO Networks  

Microsoft Academic Search

We propose a framework for providing instanta- neous backup to traffic in a hybrid RF\\/FSO mesh network. Free Space Optical (FSO) links have high bandwidth and security, making them suitable for use in backbone networks. RF links have low bandwidth, but offer high reliability in conditions where FSO links are obscured. Thus, RF links are primarily used to provide instantaneous

Abhishek Kashyap; Anuj Rawat; Mark A. Shayman

2006-01-01

393

Active-Passive Hybrid Adaptive Structures for Vibration Controls -- An Integrated Approach.  

National Technical Information Service (NTIS)

The objective of this research is to develop, validate and evaluate novel active-passive hybrid adaptive structures for real-time vibration suppressions. These structures could have the advantages of both the passive (stable, low power requirement, tail-s...

K. Wang

2000-01-01

394

Integrative control strategy of regenerative and hydraulic braking for hybrid electric car  

Microsoft Academic Search

Since electric braking involvement, the braking system of an EV, HEV and FCV becomes much more complex than conventional mechanical alone braking system. The target in this hybrid braking system is to recover the braking energy as much as possible and meanwhile maintain a good braking performance for vehicle safety. For this purpose, the control of this braking system is

Liang Chu; Wanfeng Sun; Liang Yao; Yongsheng Zhang; Yang Ou; Wenruo Wei; Minghui Liu; Jun Li

2009-01-01

395

A High-Resolution Cat Radiation Hybrid and Integrated FISH Mapping Resource for Phylogenomic Studies across Felidae  

PubMed Central

We describe the construction of a high-resolution radiation hybrid (RH) map of the domestic cat genome, which includes 2,662 markers, translating to an estimated average intermarker distance of 939 kilobases (Kb). Targeted marker selection utilized the recent feline 1.9x genome assembly, concentrating on regions of low marker density on feline autosomes and the X chromosome, in addition to regions flanking interspecies chromosomal breakpoints. Average gap (breakpoint) size between cat-human ordered conserved segments is less than 900 Kb. The map was used for a fine-scale comparison of conserved syntenic blocks with the human and canine genomes. Corroborative fluorescence in situ hybridization (FISH) data were generated using 129 domestic cat BAC-clones as probes, providing independent confirmation of the long-range correctness of the map. Cross-species hybridization of BAC probes on divergent felids from the genera Profelis (serval) and Panthera (snow leopard) provides further evidence for karyotypic conservation within felids, and demonstrates the utility of such probes for future studies of chromosome evolution within the cat family and in related carnivores. The integrated map constitutes a comprehensive framework for identifying genes controlling feline phenotypes of interest, and to aid in assembly of a higher coverage feline genome sequence.

Davis, Brian W.; Raudsepp, Terje; Wilkerson, Alison J. Pearks; Agarwala, Richa; Schaffer, Alejandro A.; Houck, Marlys; Ryder, Oliver A.; Chowdhdary, Bhanu P.; Murphy, William J.

2008-01-01

396

Integrated hybrid Raman/fiber Bragg grating interrogation scheme for distributed temperature and point dynamic strain measurements.  

PubMed

We propose and experimentally demonstrate the feasibility of an integrated hybrid optical fiber sensing interrogation technique that efficiently combines distributed Raman-based temperature sensing with fiber Bragg grating (FBG)-based dynamic strain measurements. The proposed sensing system is highly integrated, making use of a common optical source/receiver block and exploiting the advantages of both (distributed and point) sensing technologies simultaneously. A multimode fiber is used for distributed temperature sensing, and a pair of FBGs in each discrete sensing point, partially overlapped in the spectral domain, allows for temperature-independent discrete strain measurements. Experimental results report a dynamic strain resolution of 7.8 n?/?Hz within a full range of 1700 ?? and a distributed temperature resolution of 1°C at 20 km distance with 2.7 m spatial resolution. PMID:23089781

Zaidi, Farhan; Nannipieri, Tiziano; Soto, Marcelo A; Signorini, Alessandro; Bolognini, Gabriele; Di Pasquale, Fabrizio

2012-10-20

397

12.5 pm/V hybrid silicon and lithium niobate optical microring resonator with integrated electrodes.  

PubMed

We present a silicon microring resonator with a lithium niobate top cladding and integrated tuning electrodes. Submicrometer thin films of z-cut lithium niobate are bonded to silicon microring resonators via benzocyclobutene. Integrated electrodes are incorporated to confine voltage controlled electric fields within the lithium niobate thin film. The electrode design utilizes thin film metal electrodes and an optically transparent electrode wherein the silicon waveguide core serves as both an optical waveguide medium and as a conductive electrode medium. The hybrid material system combines the electro-optic functionality of lithium niobate with the high index contrast of silicon waveguides, enabling compact low tuning voltage microring resonators. Optical characterization of fabricated devices results in a measured loaded quality factor of 11,500 and a free spectral range of 7.15 nm in the infrared. The demonstrated tunability is 12.5 pm/V, which is over an order of magnitude greater than electrode-free designs. PMID:24216923

Chen, Li; Wood, Michael G; Reano, Ronald M

2013-11-01

398

Depth Mapping of Integral Images Through Viewpoint Image Extraction With a Hybrid Disparity Analysis Algorithm  

Microsoft Academic Search

Integral imaging is a technique capable of displaying 3D images with continuous parallax in full natural color. It is one of the most promising methods for producing smooth 3D images. Extracting depth information from integral image has various applications ranging from remote inspection, robotic vision, medical imaging, virtual reality, to content-based image coding and manipulation for integral imaging based 3D

Chunhong Wu; Malcolm McCormick; Amar Aggoun; S. Y. Kung

2008-01-01

399

Large-scale complementary macroelectronics using hybrid integration of carbon nanotubes and IGZO thin-film transistors.  

PubMed

Carbon nanotubes and metal oxide semiconductors have emerged as important materials for p-type and n-type thin-film transistors, respectively; however, realizing sophisticated macroelectronics operating in complementary mode has been challenging due to the difficulty in making n-type carbon nanotube transistors and p-type metal oxide transistors. Here we report a hybrid integration of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors to achieve large-scale (>1,000 transistors for 501-stage ring oscillators) complementary macroelectronic circuits on both rigid and flexible substrates. This approach of hybrid integration allows us to combine the strength of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors, and offers high device yield and low device variation. Based on this approach, we report the successful demonstration of various logic gates (inverter, NAND and NOR gates), ring oscillators (from 51 stages to 501 stages) and dynamic logic circuits (dynamic inverter, NAND and NOR gates). PMID:24923382

Chen, Haitian; Cao, Yu; Zhang, Jialu; Zhou, Chongwu

2014-01-01

400

Arsenic removal from contaminated groundwater by membrane-integrated hybrid plant: optimization and control using Visual Basic platform.  

PubMed

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

Chakrabortty, S; Sen, M; Pal, P

2014-03-01

401

The correlation functions of hard-sphere chain fluids: Comparison of the Wertheim integral equation theory with the Monte Carlo simulation  

SciTech Connect

The correlation functions of homonuclear hard-sphere chain fluids are studied using the Wertheim integral equation theory for associating fluids and the Monte Carlo simulation method. The molecular model used in the simulations is the freely jointed hard-sphere chain with spheres that are tangentially connected. In the Wertheim theory, such a chain molecule is described by sticky hard spheres with two independent attraction sites on the surface of each sphere. The OZ-like equation for this associating fluid is analytically solved using the polymer-PY closure and by imposing a single bonding condition. By equating the mean chain length of this associating hard sphere fluid to the fixed length of the hard-sphere chains used in simulation, we find that the correlation functions for the chain fluids are accurately predicted. From the Wertheim theory we also obtain predictions for the overall correlation functions that include intramolecular correlations. In addition, the results for the average intermolecular correlation functions from the Wertheim theory and from the Chiew theory are compared with simulation results, and the differences between these theories are discussed.

Chang, J.; Sandler, S.I. (Center for Molecular and Engineering Thermodynamics, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716 (United States))

1995-01-01

402

Novel Framework of Integrated Security and Safety System Using Hybrid Network Technology  

Microsoft Academic Search

Advancement in micro-electro mechanical system (MEMS) that integrate mechanical system, sensor, actuator, and electronics has contributed to significant improvement of automation system including security and safety system. This paper will propose a framework of integrated security and safety system that combines microembedded system and computer based system. The framework is designed and developed based on conceptual model of security and

Edi Saputra; K. A. Bakar; H. Herman; S. Hassan

2009-01-01

403

ENHANCED COD AND NUTRIENT REMOVAL EFFICIENCY IN A HYBRID INTEGRATED FIXED FILM ACTIVATED SLUDGE PROCESS  

Microsoft Academic Search

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.

A. A. AZIMI; B. HOOSHYARI; N. MEHRDADI; G. H. NABI BIDHENDI

404

Integration and optimization of the gas removal system for hybrid-cycle OTEC power plants  

Microsoft Academic Search

A preliminary design of the noncondensible gas removal system for a 10 mWe, land-based hybrid-cycle OTEC power plant has been developed and is presented herein. This gas removal system is very different from that used for conventional power plants because of the substantially larger and continuous noncondensible gas flow rates and lower condenser pressure levels which predicate the need for

T. J. Rabas; C. B. Panchal; H. C. Stevens

1990-01-01

405

Hybridized 3D-FDTD and circuit simulator for analysis of PCB via's signal integrity  

Microsoft Academic Search

In this paper, the equivalent circuit model containing two pairs of vias is established, and a hybrid method is applied, which combines the full-wave finite difference time domain (FDTD) with an S-parameter based macromodel by using the rational function approximation and circuit simulation. The electromagnetic feature of the model is described by S-parameters, result of the simulation of FDTD. The

Xiaoshe Zhai; Zhengxiang Song; Yingsan Geng; Jianhua Wang; Degui Chen

2006-01-01

406

Cost-effective monolithic and hybrid integration for metro and long-haul applications  

NASA Astrophysics Data System (ADS)

Today's telecommunication market is characterized by conservative business practices: tight management of costs, low risk investing and incremental upgrades, rather than the more freewheeling approach taken a few years ago. Optimizing optical components for the current and near term market involves substantial integration, but within particular bounds. The emphasis on evolution, in particular, has led to increased standardization of functions and so created extensive opportunities for integrated product offerings. The same standardization that enables commercially successful integrated functions also changes the competitive environment, and changes the emphasis for component development; shifting the innovation priority from raw performance to delivering the most effective integrated products. This paper will discuss, with specific examples from our transmitter, receiver and passives product families, our understanding of the issues based on extensive experience in delivering high end integrated products to the market, and the direction it drives optical components.

Clayton, Rick; Carter, Andy; Betty, Ian; Simmons, Timothy

2003-12-01

407

Core–shell hybrid nanogels for integration of optical temperature-sensing, targeted tumor cell imaging, and combined chemo-photothermal treatment  

Microsoft Academic Search

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

Weitai Wu; Jing Shen; Probal Banerjee; Shuiqin Zhou

2010-01-01

408

Quasi–Monte Carlo Constructions  

Microsoft Academic Search

In this chapter and the following one, we discuss the use of low-discrepancy sampling to replace the pure random sampling that forms the backbone of the Monte Carlo method. Using this alternative sampling method\\u000a in the context of multivariate integration is usually referred to as quasi–Monte Carlo. A low-discrepancy sample is one whose points are distributed in a way that

Christiane Lemieux

409

Production Engineering Measure for Hybrid Integrated Circuits for Fuze Applications. Volume 1.  

National Technical Information Service (NTIS)

The initial review of the Integrated Arming and Firing Circuits indicated a need for revision to the Specifications, in regard to the plastic packaging. Thick film processing was selected as the method to produce the devices. A computerized testing system...

T. Sciacca H. Brandt

1974-01-01

410

Hybrid Semiconductor-Molecular Integrated Circuits for Digital Electronics: CMOL Approach  

Microsoft Academic Search

\\u000a This chapter describes architectures of digital circuits including memories, general-purpose, and application-specific reconfigurable\\u000a Boolean logic circuits for the prospective hybrid CMOS\\/nanowire\\/nanodevice (“CMOL”) technology. The basic idea of CMOL circuits\\u000a is to combine the advantages of CMOS technology (including its flexibility and high fabrication yield) with those of molecular-scale\\u000a nanodevices. Two-terminal nanodevices would be naturally incorporated into nanowire crossbar fabric, enabling

Dmitri B. Strukov

411

Path-integral Monte Carlo simulation of nu3 vibrational shifts for CO2 in (He)n clusters critically tests the He-CO2 potential energy surface  

Microsoft Academic Search

Path-integral Monte Carlo simulations of the nu3 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

Hui Li; Nicholas Blinov; Pierre-Nicholas Roy; Robert J. Le Roy

2009-01-01

412

A family of time-staggered schemes for integrating hybrid DPD models for polymers: Algorithms and applications  

SciTech Connect

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 {lambda}-phage DNA molecules subjected to shear.

Symeonidis, Vasileios [Division of Applied Mathematics, Brown University, 182 George Street, Box F, Providence, RI 02912 (United States); Karniadakis, George Em [Division of Applied Mathematics, Brown University, 182 George Street, Box F, Providence, RI 02912 (United States)]. E-mail: gk@dam.brown.edu

2006-10-10

413

A family of time-staggered schemes for integrating hybrid DPD models for polymers: Algorithms and applications  

NASA Astrophysics Data System (ADS)

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.

Symeonidis, Vasileios; Karniadakis, George Em

2006-10-01

414

Trap-state-assisted white light emission from a CdSe nanocrystal integrated hybrid light-emitting diode.  

PubMed

This Letter reports on the fabrication of hybrid white-light-emitting diodes made of semiconductor nanocrystals (NCs) integrated on InGaN/GaN LEDs. Using core type and core/shell type CdSe NCs, the white light properties are systematically engineered for white light generation with high color rendering index (CRI). Unlike CdSe/ZnS core/shell NCs, which exhibited a unique narrowband edge emission, core type CdSe NCs offered extended broad emission toward orange/red wavelengths associated with deep trap states. Consequently, the light-emitting properties of the devices showed strong dependence on the type of NCs used, and devices with CdSe NCs offered admirable characteristics, such as Commission Internationale d'Eclairage coordinates of (0.356, 0.330) and a CRI as high as 87.4. PMID:21403688

Chandramohan, S; Ryu, Beo Deul; Kim, Hyun Kyu; Hong, Chang-Hee; Suh, Eun-Kyung

2011-03-15

415

Highly integrated hybrid process with ceramic ultrafiltration-membrane for advanced treatment of drinking water: a pilot study.  

PubMed

This article presents a highly integrated hybrid process for the advanced treatment of drinking water in dealing with the micro-polluted raw water. A flat sheet ceramic membrane with the pore size of 50?60 nm for ultrafiltration (UF) is used to integrate coagulation and ozonation together. At the same time, biological activated carbon filtration (BAC) is used to remove the ammonia and organic pollutants in raw water. A pilot study in the scale of 120 m(3)/d has been conducted in Southern China. The mainly-analyzed parameters include turbidity, particle counts, ammonia, total organic carbon (TOC), UV254, biological dissolved organic carbon (BDOC), dissolved oxygen (DO) as well as trans-membrane pressure (TMP). The experiments demonstrated that ceramic UF-membrane was able to remove most of turbidity and suspended particulate matters. The final effluent turbidity reached to 0.14 NTU on average. BAC was effective in removing ammonia and organic matters. Dissolved oxygen (DO) is necessary for the biodegradation of ammonia at high concentration. The removal efficiencies reached to 90% for ammonia with the initial concentration of 3.6 mg/L and 76% for TOC with the initial concentration of 3.8 mg/L. Ozonation can alter the molecular structure of organics in terms of UV254, reduce membrane fouling, and extend the operation circle. It is believed the hybrid treatment process developed in this article can achieve high performance with less land occupation and lower cost compared with the conventional processes. It is especially suitable for the developing countries in order to obtain high-quality drinking water in a cost-effective way. PMID:23705617

Guo, Jianning; Wang, Lingyun; Zhu, Jia; Zhang, Jianguo; Sheng, Deyang; Zhang, Xihui

2013-01-01

416

Material properties of one-dimensional systems studied by path-integral quantum Monte Carlo simulations and an analytical many-body model  

NASA Astrophysics Data System (ADS)

Feynman path-integral quantum Monte Carlo (QMC) simulations and an analytic many-body approach are used to study the ground state properties of one-dimensional (1D) chains in the theoretical framework of model Hamiltonians of the Hubbard type. The QMC algorithm is employed to derive position-space quantities, while band structure properties are evaluated by combining QMC data with expressions derived in momentum (k) space. Bridging link between both representations is the quasi-chemical approximation (QCA). Electronic charge fluctuations <(?n2i)> and the fluctuations of the magnetic local moments <(?s2i)> are studied as a function of the on-site density and correlation strength, which is given by the ratio between two-electron interaction and kinetic hopping. Caused by the non-analytic behaviour of the chemical potential ? = ?E/? (with E denoting the electronic energy), strict 1D systems with an on-site density of 1·0 do not exhibit the properties of a conductor for any non-zero interaction beyond the mean-field approximation. The QMC simulations lead to straightforward access to the probabilities Pi(n) of finding n = 0, 1, 2 electrons at the ith lattice site. The Pi(n) elements allow to calculate the enhancement factors on the electron spin susceptibility ?, effective electronic mass m* and Knight shift ?. m* is enhanced by a bandwidth renormalization factor D-10, ? by an element ?K mapping the additional localization of the correlated electrons in the presence of an external magnetic field B and ? by the product D-10 ?K. Available experimental data are discussed in the light of the present theoretical findings.

Böhm, Michael C.; Schulte, Joachim; Utrera, Luis

417

Hybrid Learning Environments: Merging Learning and Work Processes to Facilitate Knowledge Integration and Transitions  

Microsoft Academic Search

This paper deals with the problematic nature of the transition between education and the workplace. A smooth transition between education and the workplace requires learners to develop an integrated knowledge base, but this is problematic as most educational programmes offer knowledge and experiences in a fragmented manner, scattered over a variety of subjects, modules and (work) experiences. To overcome this

Ilya Zitter; Aimée Hoeve

2012-01-01

418

A Hybrid Content-Collaborative Recommender System Integrated into an Electronic Performance Support System  

Microsoft Academic Search

An electronic performance support system (EPSS) introduces challenges on contextualized and personalized information delivery. Recommender systems aim at delivering and suggesting relevant information according to users preferences, thus EPSSs could take advantage of the recommendation algorithms that have the effect of guiding users in a large space of possible options. The JUMP project aims at integrating an EPSS with a

Leo Iaquinta; Anna Lisa Gentile; Pasquale Lops; Marco de Gemmis; Giovanni Semeraro

2007-01-01

419

Hybrid DC and AC-Linked Microgrids: Towards Integration of Distributed Energy Resources  

Microsoft Academic Search

This paper presents a microgrid paradigm with both DC and AC links, which may provide an effective way to integrate a heterogeneous set of small-size distributed energy resources into the existing electric power infrastructure. The collection of aggregated energy resource units at each level represents those distributed resources to the upper level as a single self-regulated entity (as a DC

Zhenhua Jiang; Xunwei Yu

2008-01-01

420

Transient analysis of integrated solar\\/diesel hybrid power system using MATLAB Simulink  

Microsoft Academic Search

This paper presents Matlab simulation the dynamic behavior of small autonomous power system with solar and diesel power sources. The solar power system and the diesel generator operate in parallel. It is more cost effective than a diesel generator acting alone. For the effective integration of the solar power into the power system, a method for controlling the Inverter's operation

Takyin Taky Chan

421

Managing Change in an Integrated School--A Hong Kong Hybrid Experience  

ERIC Educational Resources Information Center

Following the world trend of inclusion in education, many schools in Hong Kong have started including students with special needs in the regular classrooms. Given the unique educational context of Hong Kong as "East meets West", and given that inclusion is essentially a concept from the West, this paper argues that Hong Kong's integration has its…

Yee, Pattie Luk Fong Yuk

2005-01-01

422

Monitoring Protein-Protein Interactions between the Mammalian Integral Membrane Transporters and PDZ-interacting Partners Using a Modified Split-ubiquitin Membrane Yeast Two-hybrid System  

Microsoft Academic Search

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

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

423

Hybrid routing technique for a fault-tolerant, integrated information network  

NASA Technical Reports Server (NTRS)

The evolutionary growth of the space station and the diverse activities onboard are expected to require a hierarchy of integrated, local area networks capable of supporting data, voice, and video communications. In addition, fault-tolerant network operation is necessary to protect communications between critical systems attached to the net and to relieve the valuable human resources onboard the space station of time-critical data system repair tasks. A key issue for the design of the fault-tolerant, integrated network is the development of a robust routing algorithm which dynamically selects the optimum communication paths through the net. A routing technique is described that adapts to topological changes in the network to support fault-tolerant operation and system evolvability.

Meredith, B. D.

1986-01-01

424

Optimization of acoustic liners by the hybrid finite element-integral approach  

NASA Technical Reports Server (NTRS)

An iterative solution technique for predicting the sound field radiated from a turbofan inlet is used to predict the optimum inlet acoustic liner. The analytical approach divides the sound field into two regions: the sound field within and near the inlet which is computed using the finite element method and the radiation field beyond the inlet which is calculated using an integral solution technique. A continuous solution is obtained by matching the finite element and integral solutions at the interface between the two regions. Using a trial and error scheme, this analytical procedure is used to calculate the impedance value of the duct liner which will produce a minimum sound pressure level in the far field. Several examples of straight and non-uniform ducts with and without flow are presented.

Sigman, R. K.; Horowitz, S. J.; Zinn, B. T.

1983-01-01

425

The ObjECTS: Framework for Integrated Assessment: Hybrid Modeling of Transportation  

Microsoft Academic Search

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

Son H. Kim; James A. Edmonds; Joshua Lurz; Steven J. Smith; Marshall A. Wise

2006-01-01

426

The objECTS Framework for integrated Assessment: Hybrid Modeling of Transportation  

Microsoft Academic Search

Technology is a central issue for the global climate change problem, requiring analysis tools that can examine the impact of specific technologies within 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

2006-01-01

427

Hybrid Integration of End-to-End Optical Interconnects on Printed Circuit Boards  

Microsoft Academic Search

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

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

428

Multi-Energy, Fast Counting Hybrid CZT Pixel Detector with Dedicated Readout Integrated Circuit  

Microsoft Academic Search

A new mixed signal front-end readout electronics integrated circuit (IC) called HILDA (Hyperspectral Imaging with Large Detector Arrays) has been developed for two-dimensional CdZnTe (CZT) pixel detector arrays. The CZT array is directly bonded on top of the IC. The CZT array and the HILDA-IC have matching geometric pixel\\/channel structure and dimensions, a 16times16 array of 0.5 mm times 0.5

Martin Clajus; Victoria B. Cajipe; Satoshi Hayakawa; T. O. Turner; Paul D. Willson

2006-01-01

429

Hybrid integration of an eight-channel WDM transmitter and receiver module at 980 nm  

NASA Astrophysics Data System (ADS)

The inherent information bandwidth of optical fibers between the wavelengths 1.3 and 1.6 micrometers is in the terahertz range. One obvious way to exploit this bandwidth is to use wavelength-division multiplexing (WDM). The Canadian Solid State Optoelectronics Consortium (SSOC), an association of industry, university, and federal government research laboratories, has been developing the component technologies required to demonstrate the operation of an eight channel WDM system. This paper discusses the integration of the transmitter (Tx) and the receiver (Rx) modules using a thin film process on alumina substrates. The Tx module contains a fully integrated eight channel DBR laser array with two quad-laser driver circuits. The signal from the lasers is combined into a single waveguide and is then carried off-chip via a polarization maintaining optical fiber. The Rx module is made up of an integrated receiver circuit, and a series of amplifiers providing the gain required for signal and clock recovery. The receiver circuit consists of an echelle grating which disperses the eight distinct wavelengths into a bank of InGaAs metal-semiconductor-metal (MSM) detectors. Some of the performance parameters of the Tx and Rx modules are presented.

Berolo, Ezio; Coyne, W.; Hua, Heng; James, R.; Kuley, R. M.; Lisicka-Skrzek, Ewa; Millar, G.; Vineberg, Karen A.; Fallahi, Mahmoud; Barber, Richard A.; Chatenoud, F.; Wang, Weijian; Koteles, Emil S.

1995-03-01

430

Using a hybrid Monte Carlo/ Slip Estimator-Genetic Algorithm (MCSE-GA) to produce high resolution estimates of paleoearthquakes from geodetic data  

NASA Astrophysics Data System (ADS)

Identifying fault sections where slip deficits have accumulated may provide a means for understanding sequences of large megathrust earthquakes. Stress accumulated during the interseismic period on an active megathrust is stored as potential slip, referred to as slip deficit, along locked sections of the fault. Analysis of the spatial distribution of slip during antecedent events along the fault will show where the locked plate has spent its stored slip. Areas of unreleased slip indicate where the potential for large events remain. The location of recent earthquakes and their distribution of slip can be estimated from instrumentally recorded seismic and geodetic data. However, long-term slip-deficit modelling requires detailed information on the size and distribution of slip for pre-instrumental events over hundreds of years covering more than one 'seismic cycle'. This requires the exploitation of proxy sources of data. Coral microatolls, growing in the intertidal zone of the outer island arc of the Sunda trench, present the possibility of reconstructing slip for a number of pre-instrumental earthquakes. Their growth is influenced by tectonic flexing of the continental plate beneath them; they act as long term recorders of the vertical component of deformation. However, the sparse distribution of data available using coral geodesy results in a under determined problem with non-unique solutions. Rather than accepting any one realisation as the definite model satisfying the coral displacement data, a Monte Carlo approach identifies a suite of models consistent with the observations. Using a Genetic Algorithm to accelerate the identification of desirable models, we have developed a Monte Carlo Slip Estimator- Genetic Algorithm (MCSE-GA) which exploits the full range of uncertainty associated with the displacements. Each iteration of the MCSE-GA samples different values from within the spread of uncertainties associated with each coral displacement. The Genetic Algorithm element of the MCSE-GA allows it to recombine the information stored in a population of randomly generated models to rapidly converge on a possible solution. These solutions are evaluated and those satisfying a threshold number of observations join an ensemble of models contributing to a final Weighted Average Model (WAM). The WAM represents a high resolution estimate of the slip distribution responsible for any given set of displacements. Analysis of the slip values of the ensemble models allows areas of high confidence to be identified where the standard deviation is low. Similarly, areas of low confidence will be found where standard deviations are high. This presentation will demonstrate the ability of the MCSE-GA to produce both accurate models of slip for a number of recent instrumentally recorded earthquakes along the Sunda Trench and estimates of slip during 1797 and 1833 paleoearthquakes that are consistent with those produced from other techniques.

Lindsay, Anthony; McCloskey, John; Simão, Nuno; Murphy, Shane; Bhloscaidh, Mairead Nic

2014-05-01

431

Verification of the Shift Monte Carlo Code with the C5G7 Reactor Benchmark.  

National Technical Information Service (NTIS)

Shift is a new hybrid Monte Carlo/deterministic radiation transport code being developed at Oak Ridge National Laboratory. At its current stage of development, Shift includes a parallel Monte Carlo capability for simulating eigenvalue and fixed-source mul...

B. T. Mervin G. I. Maldonado J. C. Wagner N. C. Sly S. W. Mosher T. M. Evans

2012-01-01

432

Integration of photoswitchable proteins, photosynthetic reaction centers and semiconductor/biomolecule hybrids with electrode supports for optobioelectronic applications.  

PubMed

Light-triggered biological processes provide the principles for the development of man-made optobioelectronic systems. This Review addresses three recently developed topics in the area of optobioelectronics, while addressing the potential applications of these systems. The topics discussed include: (i) the reversible photoswitching of the bioelectrocatalytic functions of redox proteins by the modification of proteins with photoisomerizable units or by the integration of proteins with photoisomerizable environments; (ii) the integration of natural photosynthetic reaction centers with electrodes and the construction of photobioelectrochemical cells and photobiofuel cells; and (iii) the synthesis of biomolecule/semiconductor quantum dots hybrid systems and their immobilization on electrodes to yield photobioelectrochemical and photobiofuel cell elements. The fundamental challenge in the tailoring of optobioelectronic systems is the development of means to electrically contact photoactive biomolecular assemblies with the electrode supports. Different methods to establish electrical communication between the photoactive biomolecular assemblies and electrodes are discussed. These include the nanoscale engineering of the biomolecular nanostructures on surfaces, the development of photoactive molecular wires and the coupling of photoinduced electron transfer reactions with the redox functions of proteins. The different possible applications of optobioelectronic systems are discussed, including their use as photosensors, the design of biosensors, and the construction of solar energy conversion and storage systems. PMID:22933337

Wang, Fuan; Liu, Xiaoqing; Willner, Itamar

2013-01-18

433

THE HYBRIDATION ENTERS THE ORDERING OF THE SLIPPING MODE TO INTEGRAL ACTION AND THE FUZZY ORDER ( Application To The Permanent Magnet Synchronous Machine )  

Microsoft Academic Search

This article presents a new approach to indirect vector control of permanent magnet synchronous machine. In this order the scrambled controller is added to the controller of sliding mode with integral action in order to guarantee the stability of the system. The new hybrid controller obtained is applied to the permanent magnet synchronous machine PMSM. In a first stage, we

KECHICH ABDERRAHMANE; MAZARI BENYOUNES

434

Benchmarking the OLGA lower-hybrid full-wave code for a future integration with ALOHA  

NASA Astrophysics Data System (ADS)

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.

Preinhaelter, J.; Hillairet, J.; Urban, J.

2014-02-01

435

Hybrid Integration of Waveguide Photodiode and Preamplifier IC Using Au Stud Bump  

NASA Astrophysics Data System (ADS)

The authors developed an InP photodiode (PD) module integrated with an InP HBT preamplifier IC by using an Au stud bump. Theoretical analysis shows that the deviation of the group delay linearly increases in the inductance between the PD and IC. The flip-chip bonding based on the Au stud bump effectively reduces the inductance without sacrificing the individual device performance and reliability. Experimental results show that this technique is suitable for the receiver modules designed for applications with a bandwidth greater than 40 Gb/s.

Hatta, Tatsuo; Miyahara, Toshiharu; Okada, Norio; Ishizaki, Mitsunori; Nakaji, Masaharu; Ishimura, Eitaro; Motoshima, Kuniaki

2006-08-01

436

High quality proton beams from hybrid integrated laser-driven ion acceleration systems  

NASA Astrophysics Data System (ADS)

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 15M€. 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.

Sinigardi, Stefano; Turchetti, Giorgio; Rossi, Francesco; Londrillo, Pasquale; Giove, Dario; De Martinis, Carlo; Bolton, Paul R.

2014-03-01

437

Hybrid information privacy system: integration of chaotic neural network and RSA coding  

NASA Astrophysics Data System (ADS)

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 chaos neural network series, so called spatial-temporal keys. The chaotic typing and initial seed value of chaos neural network series, encrypted by the RSA algorithm, can reproduce spatial-temporal keys. The encrypted chaotic typing and initial seed value are hidden in watermark mixed nonlinearly with message media, wrapped with convolution error correction codes for wireless 3rd generation cellular phones. The message media can be an arbitrary image. The pattern noise has to be considered during transmission and it could affect/change the spatial-temporal keys. Since any change/modification on chaotic typing or initial seed value of chaos neural network series is not acceptable, the RSA codec system must be robust and fault-tolerant via wireless channel. The robust and fault-tolerant properties of chaos neural networks (CNN) were proved by a field theory of Associative Memory by Szu in 1997. The 1-D chaos generating nodes from the logistic map having arbitrarily negative slope a = p/q generating the N-shaped sigmoid was given first by Szu in 1992. In this paper, we simulated the robust and fault-tolerance properties of CNN under additive noise and pattern noise. We also implement a private version of RSA coding and chaos encryption process on messages.

Hsu, Ming-Kai; Willey, Jeff; Lee, Ting N.; Szu, Harold H.

2005-03-01

438

Design and characterization of a hybrid-integrated MEMS scanning grating spectrometer  

NASA Astrophysics Data System (ADS)

Grating spectrometer, like the well-established Czerny-Turner, are based on an optical design consisting of several components. Typically at least two slits, two mirrors, the grating stage and a detector are required. There has been much work to reduce this effort, setups using only one mirror (Ebert - Fastie) or the replacement of the entrance slit through the use of thin optical fibers as well as integrated electronic detector arrays instead of a moving grating and an exit slit and single detector device have been applied. Reduced effort comes along with performance limitations: Either the optical resolution or throughput is affected or the use of the system is limited to the availability of detectors arrays with reasonable price. Components in micro opto electro mechanical systems (MOEMS-) technology and spectroscopic systems based thereon have been developed to improve this situation. Miniaturized scanning gratings fabricated on bonded silicon on insulator (BSOI-) wafers were used to design grating spectrometer for the near infrared requiring single detectors only. Discrete components offer flexibility but also need for adjustment of two mirrors, grating stage, fiber mount and the detector with its slit and optionally a second slit in the entrance area. Further development leads towards the integration of the slits into the MOEMS chip, thus less effort for adjustment. Flexibility might be reduced as adjustments of the optical design or grating spacing would require a new chip with own set of masks. Nevertheless if extreme miniaturization is desired this approach seems to be promising. Besides this, high volume production might be able for a comparable low price. A new chip was developed offering grating, two slits and a cavity for the detector chip. The optical design was adjusted to a planar arrangement of grating and slits. A detector buried in a chip cavity required a new mounting strategy. Other optical components were optimized and fabricated then the systems was assembled with electronics and software adjusted to the new design including some new features like integrated position sensors. A first test of systems to grant function of all components is presented. Further work will be aimed at improved performance like higher resolution and lower SNR.

Grüger, Heinrich; Knobbe, Jens; Pügner, Tino; Schenk, Harald

2013-03-01

439

Chromosome-Specific Single-Locus FISH Probes Allow Anchorage of an 1800-Marker Integrated Radiation-Hybrid/Linkage Map of the Domestic Dog Genome to All Chromosomes  

PubMed Central

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.

Breen, Matthew; Jouquand, Sophie; Renier, Corinne; Mellersh, Cathryn S.; Hitte, Christophe; Holmes, Nigel G.; Cheron, Angelique; Suter, Nicola; Vignaux, Francoise; Bristow, Anna E.; Priat, Catherine; McCann, E.; Andre, 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

440

WEB Services Networks and Technological Hybrids — The Integration Challenges of WAN Distributed Computing for ASP Providers  

NASA Astrophysics Data System (ADS)

A necessity of integration of both information systems and office software existing in organizations has had a long history. The beginning of this kind of solutions reaches back to the old generation of network protocols called EDI (Electronic Data Interchange) and EDIFACT standard, which was initiated in 1988 and has dynamically evolved ever since (S. Michalski, M. Suskiewicz, 1995). The mentioned protocol was usually used for converting documents into natural formats processed by applications. It caused problems with binary files and, furthermore, the communication mechanisms had to be modified each time new documents or applications were added. When we compare EDI with the previously used communication mechanisms, EDI was a great step forward as it was the first, big scale attempt to define standards of data interchange between the applications in business transactions (V. Leyland, 1995, p. 47).

Mroczkiewicz, Pawel

441

Hybrid integrated optical subassembly module using a polymeric wavelength division multiplexing filter based on multimode interference for 1.31- and 1.55-?m bidirectional operation  

NASA Astrophysics Data System (ADS)

We present a new configuration for a polymer wavelength division multiplexing (WDM) filter based on multimode interference. We developed a hybrid integrated subassembly module for 1.31- and 1.55-?m bidirectional operation. Active devices including a laser diode with a monitoring photodiode and a receiving photodiode were integrated on a silicon optical bench (SiOB) platform using a flip-chip bonding technique. A polymer WDM filter chip made of polymethylmethacrylate was fabricated using a hot embossing technique. We then investigated the optical performance of the transmitter and receiver subassembly module using a SiOB platform. This hybrid integrated subassembly module exhibited bidirectional 2.5-Gbit/s signal modulation with a minimum sensitivity of -20.5 dBm at a bit error rate of 10-10 and an optical crosstalk of -35 dB.

Lim, Jung Woon; Hwang, Sung Hwan; Lee, Woo-Jin; Lee, Tae Ho; Jeong, Myung Yong; Kim, Boo-Gyoun; Rho, Byung Sup

2010-06-01

442

Propulsion Airframe Aeroacoustic Integration Effects for a Hybrid Wing Body Aircraft Configuration  

NASA Technical Reports Server (NTRS)

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.

Czech, Michael J.; Thomas, Russell H.; Elkoby, Ronen

2010-01-01

443

Libya Montes  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

This image shows the rugged cratered highland region of Libya Montes. Libya Montes forms part of the rim of an ancient impact basin called Isidis. This region of the highlands is fairly dissected with valley networks. There is still debate within the scientific community as to how valley networks themselves form: surface runoff (rainfall/snowmelt) or headward erosion via groundwater sapping. The degree of dissection here in this region suggests surface runoff rather than groundwater sapping. Small dunes are also visible on the floors of some of these channels.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2002-01-01

444

Femtosecond laser polymerization of hybrid/integrated micro-optical elements and their characterization  

NASA Astrophysics Data System (ADS)

The femtosecond laser-induced multi-photon polymerization of a zirconium-silicon based sol-gel photopolymer was employed for the fabrication of a series of micro-optical elements with single and combined optical functions: convex and Fresnel lenses, gratings, solid immersion lenses on a glass slide and on the tip of an optical fiber. The microlenses were produced as polymer caps of varying radii from 10 to 90 µm. The matching of refractive indices between the polymer and substrate was exploited for the creation of composite glass-resist structures which functioned as single lenses. Using this principle, solid immersion lenses were fabricated and their performance demonstrated. The magnification of the composite solid immersion lenses corresponded to the calculated values. The surface roughness of the lenses was below ~ 30 nm, acceptable for optical applications in the visible range. In addition, the integration of micro-optical elements onto the tip of an optical fiber was demonstrated. To increase the efficiency of the 3D laser polymerization, the lenses were formed by scanning only the outer shell and polymerizing the interior by exposure to UV light.

Malinauskas, Mangirdas; Žukauskas, Albertas; Purlys, Vytautas; Belazaras, Kastytis; Momot, Andrej; Paipulas, Domas; Gadonas, Roaldas; Piskarskas, Algis; Gilbergs, Holger; Gaidukevi?i?t?, Arun?; Sakellari, Ioanna; Farsari, Maria; Juodkazis, Saulius

2010-12-01

445

Integrated Plasma Simulation of Lower Hybrid Current Drive Modification of Sawtooth in Alcator C-Mod  

NASA Astrophysics Data System (ADS)

Experiments were performed in Alcator C-Mod, where the onset time for sawteeth was delayed significantly (up to 0.5 s) relative to ohmically heated plasmas, through injection of off-axis LH current drive power [1]. In this poster we discuss simulations of these experiments using the Integrated Plasma Simulator (IPS) [2], through which driven current density profiles and hard x-ray spectra are computed using a ray tracing code (GENRAY) and Fokker Planck code (CQL3D) [3], that are executed repeatedly in time. The background plasma is evolved in these simulations using the TSC transport code with the Porcelli sawtooth model [4]. [4pt] [1] C. E. Kessel et al, Bull. of the Am. Phys. Soc. 53, Poster PP6.00074 (2008). [0pt] [2] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008). [0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Mtg. on Sim. and Mod. of Therm. Plasmas, Montreal, Canada (1992). [0pt] [4] S. C. Jardin et al, Journal Comp. Phys. 66, 481 (1986).

Bonoli, P. T.; Hubbard, A. E.; Schmidt, A. E.; Wright, J. C.; Kessel, C. E.; Batchelor, D. B.; Berry, L. A.; Harvey, R. W.

2010-11-01

446

Analytical Applications of Monte Carlo Techniques.  

ERIC Educational Resources Information Center

Described are analytical applications of the theory of random processes, in particular solutions obtained by using statistical procedures known as Monte Carlo techniques. Supercomputer simulations, sampling, integration, ensemble, annealing, and explicit simulation are discussed. (CW)

Guell, Oscar A.; Holcombe, James A.

1990-01-01

447

A compact frequency-domain photon migration system for integration into commercial hybrid small animal imaging scanners for fluorescence tomography  

NASA Astrophysics Data System (ADS)

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.

2012-12-01

448

A compact frequency-domain photon migration system for integration into commercial hybrid small animal imaging scanners for fluorescence tomography  

PubMed Central

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.

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

449

Real-time hybrid simulation of a complex bridge model with MR dampers using the convolution integral method  

NASA Astrophysics Data System (ADS)

Magneto-rheological (MR) fluid dampers can be used to reduce the traffic induced vibration in highway bridges and protect critical structural components from fatigue. Experimental verification is needed to verify the applicability of the MR dampers for this purpose. Real-time hybrid simulation (RTHS), where the MR dampers are physically tested and dynamically linked to a numerical model of the highway bridge and truck traffic, provides an efficient and effective means to experimentally examine the efficacy of MR dampers for fatigue protection of highway bridges. In this paper a complex highway bridge model with 263?178 degrees-of-freedom under truck loading is tested using the proposed convolution integral (CI) method of RTHS for a semiactive structural control strategy employing two large-scale 200 kN MR dampers. The formation of RTHS using the CI method is first presented, followed by details of the various components in the RTHS and a description of the implementation of the CI method for this particular test. The experimental results confirm the practicability of the CI method for conducting RTHS of complex systems.

Jiang, Zhaoshuo; Jig Kim, Sung; Plude, Shelley; Christenson, Richard

2013-10-01

450

Fabrication of a TFF-Attached WDM-Type Triplex Transceiver Module Using Silica PLC Hybrid Integration Technology  

NASA Astrophysics Data System (ADS)

An optical triplex transceiver (TRx) module, which consists of thin-film filter (TFF)-attached wavelength-division multiplexer (WDM) and photodiode (PD) carriers, has been fabricated using a silica planar lightwave circuit (PLC) hybrid integration technology. Two types of TFFs were attached to a diced sidewall of a silica-terraced PLC platform to realize the TFF-attached WDM. The PD carriers with a 45° mirror, on which receiving surface-illuminated PDs were bonded, were assembled with the PLC platform to form receiver (Rx) parts. As the main performances of the packaged TRx module, a very clear transmitter (Tx) eye pattern and minimum Rx sensitivity of -25.7 dBm were obtained under a 1.25-Gb/s Tx Rx operation for digital applications. For an analog Rx application