Non perturbative methods in two dimensional quantum field theory
Abdalla, Elcio; Rothe, Klaus D
1991-01-01
This book is a survey of methods used in the study of two-dimensional models in quantum field theory as well as applications of these theories in physics. It covers the subject since the first model, studied in the fifties, up to modern developments in string theories, and includes exact solutions, non-perturbative methods of study, and nonlinear sigma models.
Coding for Two Dimensional Constrained Fields
DEFF Research Database (Denmark)
Laursen, Torben Vaarbye
2006-01-01
for the No Isolated Bits constraint. Finally we present a variation of the encoding scheme of bit-stuffing that is applicable to the class of checkerboard constrained fields. It is possible to calculate the entropy of the coding scheme thus obtaining lower bounds on the entropy of the fields considered. These lower....... The important concept of entropy is introduced. In general, the entropy of a constrained field is not readily computable, but we give a series of upper and lower bounds based on one dimensional techniques. We discuss the use of a Pickard probability model for constrained fields. The novelty lies in using...... bounds are very tight for the Run-Length limited fields. Explicit bounds are given for the diamond constrained field as well....
Bounds on the capacity of constrained two-dimensional codes
DEFF Research Database (Denmark)
Forchhammer, Søren; Justesen, Jørn
2000-01-01
Bounds on the capacity of constrained two-dimensional (2-D) codes are presented. The bounds of Calkin and Wilf apply to first-order symmetric constraints. The bounds are generalized in a weaker form to higher order and nonsymmetric constraints. Results are given for constraints specified by run...
Two-Dimensional Tail-Biting Convolutional Codes
Alfandary, Liam
2011-01-01
The multidimensional convolutional codes are an extension of the notion of convolutional codes (CCs) to several dimensions of time. This paper explores the class of two-dimensional convolutional codes (2D CCs) and 2D tail-biting convolutional codes (2D TBCCs), in particular, from several aspects. First, we derive several basic algebraic properties of these codes, applying algebraic methods in order to find bijective encoders, create parity check matrices and to inverse encoders. Next, we discuss the minimum distance and weight distribution properties of these codes. Extending an existing tree-search algorithm to two dimensions, we apply it to find codes with high minimum distance. Word-error probability asymptotes for sample codes are given and compared with other codes. The results of this approach suggest that 2D TBCCs can perform better than comparable 1D TBCCs or other codes. We then present several novel iterative suboptimal algorithms for soft decoding 2D CCs, which are based on belief propagation. Two ...
Non-Perturbative Two-Dimensional Dilaton Gravity
Mikovic, A
1993-01-01
We present a review of the canonical quantization approach to the problem of non-perturbative 2d dilaton gravity. In the case of chiral matter we describe a method for solving the constraints by constructing a Kac-Moody current algebra. For the models of interest, the relevant Kac-Moody algebras are based on SL(2,R) X U(1) group and on an extended 2d Poincare group. As a consequence, the constraints become free-field Virasoro generators with background charges. We argue that the same happens in the non-chiral case. The problem of the corresponding BRST cohomology is discussed as well as the unitarity of the theory. One can show that the theory is unitary by chosing a physical gauge, and hence the problem of transitions from pure into mixed sates is absent. Implications for the physics of black holes are discussed. (Based on the talks presented at Trieste conference on Gauge Theories, Applied Supersymmetry and Quantum Gravity, May 1993 and at Danube '93 Workshop, Belgrade, Yugoslavia, June 1993)
Ultraviolet finiteness of Chiral Perturbation Theory for two-dimensional Quantum Electrodynamics
Paston, S A; Franke, V A
2003-01-01
We consider the perturbation theory in the fermion mass (chiral perturbation theory) for the two-dimensional quantum electrodynamics. With this aim, we rewrite the theory in the equivalent bosonic form in which the interaction is exponential and the fermion mass becomes the coupling constant. We reformulate the bosonic perturbation theory in the superpropagator language and analyze its ultraviolet behavior. We show that the boson Green's functions without vacuum loops remain finite in all orders of the perturbation theory in the fermion mass.
New Two-dimensional Modified Quadratic Congruence Code/Optical Orthogonal Code for OCDMA
Institute of Scientific and Technical Information of China (English)
WANG Dong; QIU Luo-lin; ZHANG Jin-rong; TANG Xian-lun; CAO Chang-xiu
2007-01-01
A new family of two-dimensional optical orthogonal code(2-DOOC), namely, modified quadratic congruence code(MQCC )/optical orthogonal code(OOC) is proposed who employs MQCC and OOC as wavelength hopping and time-spreading patterns, respectively. Through analyzing the performance of MQCC/OOC, we can see that the correlation properties of the MQCC/OOC are still ideal. Simultaneously, our analysis shows that the proposed new code families can get more cardinalities than other codes and can improve the bit error rate(BER) of optical code division multiple access(OCDMA) effectively.
Intensity Coding in Two-Dimensional Excitable Neural Networks
Copelli, Mauro
2016-01-01
In the light of recent experimental findings that gap junctions are essential for low level intensity detection in the sensory periphery, the Greenberg-Hastings cellular automaton is employed to model the response of a two-dimensional sensory network to external stimuli. We show that excitable elements (sensory neurons) that have a small dynamical range are shown to give rise to a collective large dynamical range. Therefore the network transfer (gain) function (which is Hill or Stevens law-like) is an emergent property generated from a pool of small dynamical range cells, providing a basis for a "neural psychophysics". The growth of the dynamical range with the system size is approximately logarithmic, suggesting a functional role for electrical coupling. For a fixed number of neurons, the dynamical range displays a maximum as a function of the refractory period, which suggests experimental tests for the model. A biological application to ephaptic interactions in olfactory nerve fascicles is proposed.
Directory of Open Access Journals (Sweden)
Musa Danjuma SHEHU
2008-06-01
Full Text Available This paper lays emphasis on formulation of two dimensional differential games via optimal control theory and consideration of control systems whose dynamics is described by a system of Ordinary Differential equation in the form of linear equation under the influence of two controls U(. and V(.. Base on this, strategies were constructed. Hence we determine the optimal strategy for a control say U(. under a perturbation generated by the second control V(. within a given manifold M.
Soliton solutions of the two-dimensional KdV-Burgers equation by homotopy perturbation method
Energy Technology Data Exchange (ETDEWEB)
Molabahrami, A. [Department of Mathematics, Ilam University, PO Box 69315516, Ilam (Iran, Islamic Republic of)], E-mail: a_m_bahrami@yahoo.com; Khani, F. [Department of Mathematics, Ilam University, PO Box 69315516, Ilam (Iran, Islamic Republic of); Bakhtar Institute of Higher Education, PO Box 696, Ilam (Iran, Islamic Republic of)], E-mail: farzad_khani59@yahoo.com; Hamedi-Nezhad, S. [Bakhtar Institute of Higher Education, PO Box 696, Ilam (Iran, Islamic Republic of)
2007-10-29
In this Letter, the He's homotopy perturbation method (HPM) to finding the soliton solutions of the two-dimensional Korteweg-de Vries Burgers' equation (tdKdVB) for the initial conditions was applied. Numerical solutions of the equation were obtained. The obtained solutions, in comparison with the exact solutions admit a remarkable accuracy. The results reveal that the HPM is very effective and simple.
Two-dimensional QR-coded metamaterial absorber
Sui, Sai; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Zhang, Jieqiu; Qu, Shaobo
2016-01-01
In this paper, the design of metamaterial absorbers is proposed based on QR coding and topology optimization. Such absorbers look like QR codes and can be recognized by decoding softwares as well as mobile phones. To verify the design, two lightweight wideband absorbers are designed, which can achieve wideband absorption above 90 % in 6.68-19.30 and 7.00-19.70 GHz, respectively. More importantly, polarization-independent absorption over 90 % can be maintained under incident angle within 55°. The QR code absorber not only can achieve wideband absorption, but also can carry information such as texts and Web sites. They are of important values in applications such identification and electromagnetic protection.
Stability of a compressible two-dimensional vortex under a three-dimensional perturbation
Broadbent, E. G.
1984-04-01
It was shown by Kelvin that a two-dimensional vortex under a two-dimensional disturbance in incompressible flow responds at a discrete set of eigenvalues. These were found by Broadbent and Moore (1979) to become unstable in a compressible fluid. Three-dimensional perturbations are shown here also to be unstable, provided that the wavelength is greater than some critical value that depends on the Mach number of the vortex. A definition is given of a critical boundary dividing stable from unstable modes. Whereas the results for the most part relate to a Rankine vortex, some are also given for a vortex with a different velocity profile within the core; qualitatively, the same type of behavior is observed.
Bounds on the Capacity of Weakly constrained two-dimensional Codes
DEFF Research Database (Denmark)
Forchhammer, Søren
2002-01-01
Upper and lower bounds are presented for the capacity of weakly constrained two-dimensional codes. The maximum entropy is calculated for two simple models of 2-D codes constraining the probability of neighboring 1s as an example. For given models of the coded data, upper and lower bounds...
A minimum action method for small random perturbations of two-dimensional parallel shear flows
Wan, Xiaoliang
2013-02-01
In this work, we develop a parallel minimum action method for small random perturbations of Navier-Stokes equations to solve the optimization problem given by the large deviation theory. The Freidlin-Wentzell action functional is discretized by hp finite elements in time direction and spectral methods in physical space. A simple diagonal preconditioner is constructed for the nonlinear conjugate gradient solver of the optimization problem. A hybrid parallel strategy based on MPI and OpenMP is developed to improve numerical efficiency. Both h- and p-convergence are obtained when the discretization error from physical space can be neglected. We also present preliminary results for the transition in two-dimensional Poiseuille flow from the base flow to a non-attenuated traveling wave.
Du, Yijun; Segall, Paul; Gao, Huajian
1994-07-01
Quasi-static elastic dislocations in a homogeneous elastic half-space are commonly used to model earthquake faulting processes. Recent studies of the 1989 Kalapana, Hawaii, and Loma Prieta, California, earthquakes suggest that spatial variations in elastic properties are necessary to reconcile geodetic and seismic results. In this paper, we use a moduli perturbation approach to investigate the effect of lateral and vertical variations in elastic properties on the elastic fields produced by dislocations. The method is simple, efficient, and in some cases leads to closed form solutions. The zero-order solution is simply the solution for a homogeneous body. The first-order correction for elastic heterogeneity is given by a volume integral involving the spatial variations in moduli, the displacements due to a dislocation in a homogeneous half-space, and the half-space Green's function. The same representation can be also used to obtain higher-order solutions. If there are only piecewise constant variations in shear modulus, the volume integral can be reduced to a surface integral (or line integral in two-dimensions). Comparisons with the analytical solutions for a screw dislocation in a layered medium suggest that the perturbation solutions are valid for nearly an order of magnitude variation in modulus. It is shown that a simple two-dimensional model with both vertical and lateral variations in the elastic properties may explain a large part of the discrepancy between seismic and geodetically inferred fault depths for the 1989 Kalapana, Hawaii, earthquake.
Luukko, P J J
2013-01-01
We present a code for solving the single-particle, time-independent Schr\\"odinger equation in two dimensions. Our program utilizes the imaginary time propagation (ITP) algorithm, and it includes the most recent developments in the ITP method: the arbitrary order operator factorization and the exact inclusion of a (possibly very strong) magnetic field. Our program is able to solve thousands of eigenstates of a two-dimensional quantum system in reasonable time with commonly available hardware. The main motivation behind our work is to allow the study of highly excited states and energy spectra of two-dimensional quantum dots and billiard systems with a single versatile code, e.g., in quantum chaos research. In our implementation we emphasize a modern and easily extensible design, simple and user-friendly interfaces, and an open-source development philosophy.
2013-01-01
We present a code for solving the single-particle, time-independent Schr\\"odinger equation in two dimensions. Our program utilizes the imaginary time propagation (ITP) algorithm, and it includes the most recent developments in the ITP method: the arbitrary order operator factorization and the exact inclusion of a (possibly very strong) magnetic field. Our program is able to solve thousands of eigenstates of a two-dimensional quantum system in reasonable time with commonly available hardware. ...
Steinke, Ronald J.
1989-01-01
The Rai ROTOR1 code for two-dimensional, unsteady viscous flow analysis was applied to a supersonic throughflow fan stage design. The axial Mach number for this fan design increases from 2.0 at the inlet to 2.9 at the outlet. The Rai code uses overlapped O- and H-grids that are appropriately packed. The Rai code was run on a Cray XMP computer; then data postprocessing and graphics were performed to obtain detailed insight into the stage flow. The large rotor wakes uniformly traversed the rotor-stator interface and dispersed as they passed through the stator passage. Only weak blade shock losses were computerd, which supports the design goals. High viscous effects caused large blade wakes and a low fan efficiency. Rai code flow predictions were essentially steady for the rotor, and they compared well with Chima rotor viscous code predictions based on a C-grid of similar density.
Numerical model for two-dimensional hydrodynamics and energy transport. [VECTRA code
Energy Technology Data Exchange (ETDEWEB)
Trent, D.S.
1973-06-01
The theoretical basis and computational procedure of the VECTRA computer program are presented. VECTRA (Vorticity-Energy Code for TRansport Analysis) is designed for applying numerical simulation to a broad range of intake/discharge flows in conjunction with power plant hydrological evaluation. The code computational procedure is based on finite-difference approximation of the vorticity-stream function partial differential equations which govern steady flow momentum transport of two-dimensional, incompressible, viscous fluids in conjunction with the transport of heat and other constituents.
Simulation study of scalings in scrape-off layer plasma by two-dimensional transport code
Energy Technology Data Exchange (ETDEWEB)
Itoh, S.-I.; Ueda, Noriaki; Itoh, Kimitaka (National Inst. for Fusion Science, Nagoya (Japan))
1990-07-01
Scrape-off Layer (SOL) plasma and divertor plasma in Tokamaks were numerically analyzed using a two-dimensional time-dependent transport code (UEDA code). Plasma transport in the SOL and the divertor region was studied for given particle and heat sources from the main plasma. A scaling study of the density, the temperature and their fall-off lengths was carried out for the JFT-2M Tokamak. The results show the inter-relations between the divertor plasma parameters and core plasma confinement. The operational conditions of the core necessary to guarantee the divertor performance are discussed. (author).
A Two-Dimensional Fem Code for Impedance Calculation in High Frequency Domain
Energy Technology Data Exchange (ETDEWEB)
Wang, Lanfa; /SLAC; Lee, Lie-Quan; /SLAC; Stupakov, Gennady; /SLAC
2010-08-25
A new method, using the parabolic equation (PE), for the calculation of both high-frequency impedances of small-angle taper (or collimator) is developed in [1]. One of the most important advantages of the PE approach is that it eliminates the spatial scale of the small wavelength from the problem. As a result, only coarser spatial meshes are needed in calculating the numerical solution of the PE. We developed a new code based on Finite Element Method (FEM) which can handle arbitrary profile of a transition and speed up the calculation by orders of magnitude. As a first step, we completed and benchmarked a two-dimensional code. It can be upgraded to three-dimensional geometry.
Loop equations and Virasoro constraints in non-perturbative two-dimensional quantum gravity
Energy Technology Data Exchange (ETDEWEB)
Dijkgraaf, R.; Verlinde, H. (Princeton Univ., NJ (USA). Joseph Henry Labs.); Verlinde, E. (Institute for Advanced Study, Princeton, NJ (USA). School of Natural Sciences)
1991-01-21
We give a derivation of the loop equation for two-dimensional gravity from the KdV equations and the string equation of the one-matrix model. We find that the loop equation is equivalent to an infinite set of linear constraints on the square root of the partition function satisfying the Virasoro algebra. We give an interpretation of these equations in topological gravity and discuss their extension to multi-matrix models. For the multi-critical models the loop equation naturally singles out the operators corresponding to the primary fields of the minimal models. (orig.).
Loop Equations and Virasoro Constraints in Non-Perturbative Two-Dimensional Quantum Gravity
Dijkgraaf, Robbert; Verlinde, Herman; Verlinde, Erik
We give a derivation of the loop equation for two-dimensional gravity from the KdV equations and the string equation of the one-matrix model. We find that the loop equation is equivalent to an infinite set of linear constraints on the square root of the partition function satisfying the Virasoro algebra. We give an interpretation of these equations in topological gravity and discuss their extension to multi-matrix models. For the multi-critical models the loop equation naturally singles out the operators corresponding to the primary fields of the minimal models.
Parallel processing method for two-dimensional Sn transport code DOT3.5
Energy Technology Data Exchange (ETDEWEB)
Uematsu, Mikio [Toshiba Corp., Kawasaki, Kanagawa (Japan)
1998-03-01
A parallel processing method for the two-dimensional Sn transport code DOT3.5 has been developed to achieve drastic reduction of computation time. In the proposed method, parallelization is made with angular domain decomposition and/or space domain decomposition. Calculational speedup for parallel processing by angular domain decomposition is achieved by minimizing frequency of communications between processing elements. As for parallel processing by space domain decomposition, two-step rescaling method consisting of segmentwise rescaling and the ordinary pointwise rescaling have been developed to accelerate convergence, which will otherwise be degraded because of discontinuity at the segment boundaries. The developed method was examined with a Sun workstation using the PVM message-passing library, and sufficient speedup was observed. (author)
Luukko, P. J. J.; Räsänen, E.
2013-03-01
We present a code for solving the single-particle, time-independent Schrödinger equation in two dimensions. Our program utilizes the imaginary time propagation (ITP) algorithm, and it includes the most recent developments in the ITP method: the arbitrary order operator factorization and the exact inclusion of a (possibly very strong) magnetic field. Our program is able to solve thousands of eigenstates of a two-dimensional quantum system in reasonable time with commonly available hardware. The main motivation behind our work is to allow the study of highly excited states and energy spectra of two-dimensional quantum dots and billiard systems with a single versatile code, e.g., in quantum chaos research. In our implementation we emphasize a modern and easily extensible design, simple and user-friendly interfaces, and an open-source development philosophy. Catalogue identifier: AENR_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AENR_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 3 No. of lines in distributed program, including test data, etc.: 11310 No. of bytes in distributed program, including test data, etc.: 97720 Distribution format: tar.gz Programming language: C++ and Python. Computer: Tested on x86 and x86-64 architectures. Operating system: Tested under Linux with the g++ compiler. Any POSIX-compliant OS with a C++ compiler and the required external routines should suffice. Has the code been vectorised or parallelized?: Yes, with OpenMP. RAM: 1 MB or more, depending on system size. Classification: 7.3. External routines: FFTW3 (http://www.fftw.org), CBLAS (http://netlib.org/blas), LAPACK (http://www.netlib.org/lapack), HDF5 (http://www.hdfgroup.org/HDF5), OpenMP (http://openmp.org), TCLAP (http://tclap.sourceforge.net), Python (http://python.org), Google Test (http://code.google.com/p/googletest/) Nature of problem: Numerical calculation
Bassetto, A.; Nardelli, G.; Torrielli, A.
2002-10-01
Commutative Yang-Mills theories in 1+1 dimensions exhibit an interesting interplay between geometrical properties and U(N) gauge structures: in the exact expression of a Wilson loop with n windings a nontrivial scaling intertwines n and N. In the noncommutative case the interplay becomes tighter owing to the merging of space-time and ``internal'' symmetries in a larger gauge group U(∞). We perform an explicit perturbative calculation of such a loop up to O(g6) rather surprisingly, we find that in the contribution from the crossed graphs (the genuine noncommutative terms) the scaling we mentioned occurs for large n and N in the limit of maximal noncommutativity θ=∞. We present arguments in favor of the persistence of such a scaling at any perturbative order and succeed in summing the related perturbative series.
A two-dimensional mutate-and-map strategy for non-coding RNA structure
Kladwang, Wipapat; Vanlang, Christopher C.; Cordero, Pablo; Das, Rhiju
2011-12-01
Non-coding RNAs fold into precise base-pairing patterns to carry out critical roles in genetic regulation and protein synthesis, but determining RNA structure remains difficult. Here, we show that coupling systematic mutagenesis with high-throughput chemical mapping enables accurate base-pair inference of domains from ribosomal RNA, ribozymes and riboswitches. For a six-RNA benchmark that has challenged previous chemical/computational methods, this ‘mutate-and-map’ strategy gives secondary structures that are in agreement with crystallography (helix error rates, 2%), including a blind test on a double-glycine riboswitch. Through modelling of partially ordered states, the method enables the first test of an interdomain helix-swap hypothesis for ligand-binding cooperativity in a glycine riboswitch. Finally, the data report on tertiary contacts within non-coding RNAs, and coupling to the Rosetta/FARFAR algorithm gives nucleotide-resolution three-dimensional models (helix root-mean-squared deviation, 5.7 Å) of an adenine riboswitch. These results establish a promising two-dimensional chemical strategy for inferring the secondary and tertiary structures that underlie non-coding RNA behaviour.
Scalar Perturbations of two-dimensional Horava-Lifshitz Black Holes
Cruz, Miguel; Saavedra, Joel; Vargas-Arancibia, Diego
2015-01-01
In this article, we study the stability of black hole solutions found in the context of dilatonic Horava-Lifshitz gravity in $1+1$ dimensions by means of the quasinormal modes approach. In order to find the corresponding quasinormal modes, we consider the perturbations of massive and massless scalar fields minimally coupled to gravity. In both cases, we found that the quasinormal modes have a discrete spectrum and are completely imaginary, which leads to damping modes. For a massive scalar field and a non-vanishing cosmological constant, our results suggest unstable behaviour for large values of the scalar field mass.
Scalar perturbations of two-dimensional Horava-Lifshitz black holes
Energy Technology Data Exchange (ETDEWEB)
Cruz, Miguel; Gonzalez-Espinoza, Manuel; Saavedra, Joel; Vargas-Arancibia, Diego [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile)
2016-02-15
In this article, we study the stability of black hole solutions found in the context of dilatonic Horava-Lifshitz gravity in 1 + 1 dimensions by means of the quasinormal modes approach. In order to find the corresponding quasinormal modes, we consider the perturbations of massive and massless scalar fields minimally coupled to gravity. In both cases, we found that the quasinormal modes have a discrete spectrum and are completely imaginary, which leads to damping modes. For a massive scalar field and a non-vanishing cosmological constant, our results suggest unstable behavior for large values of the scalar field mass. (orig.)
Sohier, Thibault; Calandra, Matteo; Mauri, Francesco
2017-08-01
The ability to perform first-principles calculations of electronic and vibrational properties of two-dimensional heterostructures in a field-effect setup is crucial for the understanding and design of next-generation devices. We present here an implementation of density functional perturbation theories tailored for the case of two-dimensional heterostructures in field-effect configuration. Key ingredients are the inclusion of a truncated Coulomb interaction in the direction perpendicular to the slab and the possibility of simulating charging of the slab via field effects. With this implementation we can access total energies, force and stress tensors, the vibrational properties and the electron-phonon interaction. We demonstrate the relevance of the method by studying flexural acoustic phonons and their coupling to electrons in graphene doped by field effect. In particular, we show that while the electron-phonon coupling to those phonons can be significant in neutral graphene, it is strongly screened and negligible in doped graphene, in disagreement with other recent first-principles reports. Consequently, the gate-induced coupling with flexural acoustic modes would not be detectable in transport measurements on doped graphene.
The Two-dimensional Code QR Code Encoding of Principle and Realization%二维条码QR Code编码原理及实现
Institute of Scientific and Technical Information of China (English)
黄吉兰
2013-01-01
In the implementation of the two-dimensional code encoding, to analysis QR Code structure of the two-dimensional barcode, the encoding step, the encoding principle and the Reed-Solomon algorithm, for instance,in digital mode,according to QR Code coding theory to describes how to achieve the two-dimensional code QR Code encoding, error correction and other functions. In the VC++ programming environment, achieved the two-dimensional code QR Code program designed, by the testing repeatedly for the two-dimensional coding program.%在二维码编码的实现过程中,分析了QR Code二维条码的结构、编码步骤、编码原理和Reed-Solomon算法,并以数字模式为实例按照QR Code编码原理直观的描述了实现二维码QR Code的编码、纠错等功能.采用VC++的编程环境,通过对二维码编码程序反复测试,实现了二维码QR Code的编码程序设计.
MULTI2D - a computer code for two-dimensional radiation hydrodynamics
Ramis, R.; Meyer-ter-Vehn, J.; Ramírez, J.
2009-06-01
required. Nature of problem: In inertial confinement fusion and related experiments with lasers and particle beams, energy transport by thermal radiation becomes important. Under these conditions, the radiation field strongly interacts with the hydrodynamic motion through emission and absorption processes. Solution method: The equations of radiation transfer coupled with Lagrangian hydrodynamics, heat diffusion and beam tracing (laser or ions) are solved, in two-dimensional axial-symmetric geometry ( R-Z coordinates) using a fractional step scheme. Radiation transfer is solved with angular resolution. Matter properties are either interpolated from tables (equations-of-state and opacities) or computed by user routines (conductivities and beam attenuation). Restrictions: The code has been designed for typical conditions prevailing in inertial confinement fusion (ns time scale, matter states close to local thermodynamical equilibrium, negligible radiation pressure, …). Although a wider range of situations can be treated, extrapolations to regions beyond this design range need special care. Unusual features: A special computer language, called r94, is used at top levels of the code. These parts have to be converted to standard C by a translation program (supplied as part of the package). Due to the complexity of code (hydro-code, grid generation, user interface, graphic post-processor, translator program, installation scripts) extensive manuals are supplied as part of the package. Running time: 567 seconds for the example supplied.
Further two-dimensional code development for Stirling space engine components
Ibrahim, Mounir; Tew, Roy C.; Dudenhoefer, James E.
1990-01-01
The development of multidimensional models of Stirling engine components is described. Two-dimensional parallel plate models of an engine regenerator and a cooler were used to study heat transfer under conditions of laminar, incompressible oscillating flow. Substantial differences in the nature of the temperature variations in time over the cycle were observed for the cooler as contrasted with the regenerator. When the two-dimensional cooler model was used to calculate a heat transfer coefficient, it yields a very different result from that calculated using steady-flow correlations. Simulation results for the regenerator and the cooler are presented.
Institute of Scientific and Technical Information of China (English)
Hongxi Yin; Wei Liang; Le Ma; Liqiao Qin
2009-01-01
A new generation algorithm of two-dimensional triple-codeweight asymmetric optical orthogonal codes for optical code division multiple access (OCDMA) networks is proposed. The code cardinality is obtained and the error-probability performance for corresponding OCDMA system is analyzed. The codes with two constraints (i.e., auto- and cross-correlation properties) being unequal are taken into account. On the premise of fixed system resources, the code cardinality can be significantly improved. By analysis of the error-probability performance, it is shown that the codes with different parameters have different performances. Therefore, this type of codes can be applied to support diverse quality of service (QoS) and satisfy the quality requirement of different multimedia or distinct users, and simultaneously make the better use of bandwidth resources in optical networks.
Directory of Open Access Journals (Sweden)
Chu Jianli
2013-09-01
Full Text Available This article designs a new mobile-phone entrance guard system, uses the encryption two-dimensional code for identity authentication. Different from other similar products in the market, this system does not rely on specialized mobile phone card or NFC (near field communication module. It can be directly realized through mobile-phone software, and it can be operated simple and safer. This article designs the whole system model, includes structure, function and workflow. It also analyzes and researches the main algorithms used in the system, which include security policy algorithm, encryption two-dimensional code algorithm and image recognition algorithm. Finally, it provides the solution method for the problem in the experimental simulation. It also evaluated and summarized the experimental results.
Coding/decoding two-dimensional images with orbital angular momentum of light.
Chu, Jiaqi; Li, Xuefeng; Smithwick, Quinn; Chu, Daping
2016-04-01
We investigate encoding and decoding of two-dimensional information using the orbital angular momentum (OAM) of light. Spiral phase plates and phase-only spatial light modulators are used in encoding and decoding of OAM states, respectively. We show that off-axis points and spatial variables encoded with a given OAM state can be recovered through decoding with the corresponding complimentary OAM state.
Modeling strong motions produced by earthquakes with two-dimensional numerical codes
Helmberger, Donald V.; Vidale, John E.
1988-01-01
We present a scheme for generating synthetic point-source seismograms for shear dislocation sources using line source (two-dimensional) theory. It is based on expanding the complete three-dimensional solution of the wave equation expressed in cylindrical coordinates in an asymptotic form which provides for the separation of the motions into SH and P-SV systems. We evaluate the equations of motion with the aid of the Cagniard-de Hoop technique and derive close-formed expressions appropriate fo...
Energy Technology Data Exchange (ETDEWEB)
Muir, D.W.; Davidson, J.W.; Dudziak, D.J.; Davierwalla, D.M.; Higgs, C.E.; Stepanek, J.
1988-01-01
The lack of suitable benchmark problems makes it difficult to test sensitivity codes with a covariance library. A benchmark problem has therefore been defined for one- and two-dimensional sensitivity and uncertainity analysis codes and code systems. The problem, representative of a fusion reactor blanket, has a simple, three-zone )tau)-z geometry containing a D-T fusion neutron source distributed in a central void region surrounded by a thick /sup 6/LiH annulus. The response of interest is the /sup 6/Li tritium production per source neutron, T/sub 6/. The calculation has been performed with SENSIBL using other codes from the AARE code system as a test of both SENSIBL and the linked, modular system. The caluclation was performed using the code system in the standard manner with a covariance data library in the COVFILS-2 format but modified to contain specifically tailored covariance data for H and /sup 6/Li (Path A). The calculation was also performed by a second method which uses specially perturbed H and Li cross sections (Path B). This method bypasses SENSIBL and allows a hand calculation of the benchmark T/sub 6/ uncertainties. The results of Path A and Path B were total uncertainties in T/sub 6/ of 0.21% and 0.19%, respectively. The closeness of the results for this challenging test gives confidence that SENSIBL and the AARE system will perform well for realistic sensitivity and uncertainty analyses
FX2-TH: a two-dimensional nuclear reactor kinetics code with thermal-hydraulic feedback
Energy Technology Data Exchange (ETDEWEB)
Shober, R.A.; Daly, T.A.; Ferguson, D.R.
1978-10-01
FX2-TH is a two-dimensional, time-dependent nuclear reactor kinetics program with thermal and hydraulic feedback. The neutronics model used is multigroup neutron diffusion theory. The following geometry options are available: x, r, x-y, r-z, theta-r, and triangular. FX2-TH contains two basic thermal and hydraulic models: a simple adiabatic fuel temperature calculation, and a more detailed model consisting of an explicit representation of a fuel pin, gap, clad, and coolant. FX2-TH allows feedback effects from both fuel temperature (Doppler) and coolant temperature (density) changes. FX2-TH will calculate a consistent set of steady state conditions by iterating between the neutronics and thermal-hydraulics until convergence is reached. The time-dependent calculation is performed by the use of the improved quasistatic method. A disk editing capability is available. FX2-TH is operational on IBM system 360 or 370 computers and on the CDC 7600.
MARG2D code. 1. Eigenvalue problem for two dimensional Newcomb equation
Energy Technology Data Exchange (ETDEWEB)
Tokuda, Shinji [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Watanabe, Tomoko
1997-10-01
A new method and a code MARG2D have been developed to solve the 2-dimensional Newcomb equation which plays an important role in the magnetohydrodynamic (MHD) stability analysis in an axisymmetric toroidal plasma such as a tokamak. In the present formulation, an eigenvalue problem is posed for the 2-D Newcomb equation, where the weight function (the kinetic energy integral) and the boundary conditions at rational surfaces are chosen so that an eigenfunction correctly behaves as the linear combination of the small solution and the analytical solutions around each of the rational surfaces. Thus, the difficulty on solving the 2-D Newcomb equation has been resolved. By using the MARG2D code, the ideal MHD marginally stable state can be identified for a 2-D toroidal plasma. The code is indispensable on computing the outer-region matching data necessary for the resistive MHD stability analysis. Benchmark with ERATOJ, an ideal MHD stability code, has been carried out and the MARG2D code demonstrates that it indeed identifies both stable and marginally stable states against ideal MHD motion. (author)
Phase coding by grid cells in unconstrained environments: Two-dimensional (2D) phase precession
Climer, Jason R.; Newman, Ehren L.; Hasselmo, Michael E.
2014-01-01
Action potential timing is thought to play a critical role in neural representation. For example, theta phase precession is a robust phenomenon exhibited by spatial cells of the rat entorhinal-hippocampal circuit. In phase precession, the time a neuron fires relative to the phase of theta rhythm (6-10Hz) oscillations in the local field potential reduces uncertainty about the position of the animal. This relationship between neural firing and behavior has made precession an important constraint for hypothetical mechanisms of temporal coding. However, challenges exist in identifying what regulates the spike timing of these cells. We have developed novel analytical techniques for mapping between behavior and neural firing that provide sufficient sensitivity to examine features of grid cell phase coding in open environments. Here, we show robust, omnidirectional phase precession by entorhinal grid cells in openfield enclosures. We present evidence that full phase precession persists regardless of how close the animal comes to the center of a firing field. We found many conjunctive grid cells, previously thought to be phase locked, also exhibit phase coding. However, we were unable to detect directional or field specific phase coding predicted by some variants of models. Finally, we present data that suggests bursting of layer II grid cells contributes to the bimodality of phase precession. We discuss implications of these observations for models of temporal coding and propose the utility of these techniques in other domains where behavior is aligned to neural spiking. PMID:23718553
QR Code 二维码在准考证中的应用%Application of QR code two - dimensional code in the examination certificate
Institute of Scientific and Technical Information of China (English)
李文江; 陈诗琴
2015-01-01
针对现有纸质准考证身份验证存在的缺点，基于 QR Code 二维码技术，设计并实现了准考证的二维码生成、发布与识别，并从需求分析与技术思路、应用设计、具体实现和实际运行效果等方面进行阐述。二维码的应用可以极大地方便考试组织部门和考生。%Based on the QR Code technology,this paper designs and implements the confirmation code generation,distribution and identification according to the disadvantages of the existing paper ticket authenti-cation,and the paper explains in detail from the aspects of demand analysis and technical ideas,application design,implementation and practical operation effect. The application of two - dimensional code promotes the fairness of the exam. Also it greatly facilitates the examination of the organization department and the candidates.
Directory of Open Access Journals (Sweden)
Mihai-Victor PRICOP
2010-09-01
Full Text Available The present paper introduces a numerical approach of static linear elasticity equations for anisotropic materials. The domain and boundary conditions are simple, to enhance an easy implementation of the finite difference scheme. SOR and gradient are used to solve the resulting linear system. The simplicity of the geometry is also useful for MPI parallelization of the code.
Extended pseudorandom sequences and two-dimensional coding collimators based on them
Fedorov, G. A.; Tereshchenko, S. A.
2007-01-01
A new extensive class of one-dimensional binary sequences, called extended pseudorandom sequences, is proposed which enables a radiation-physics experiment to be optimized more completely and enables problems of planar emission tomography to be solved effectively using integral-code measuring system
CSQII: a two-dimensional Eulerian code for computation of material motion in two dimensions
Energy Technology Data Exchange (ETDEWEB)
McGlaun, J M; Thompson, S L
1980-01-01
CSQII is a general-purpose code with a wide variety of options: rectangular or cylindrical coordinates, up to ten materials, allowance for void, elestic-plastic or distended material, inclusion of energy sources or gravity. The basic solution scheme integrates the Lagrangian form of the conservation equations through a time step and then explicity rezones back to the Eulerian grid. The following aspects are treated in some detail: equation of state, momentum balance, energy balance, rezoning, and radiation. (RWR)
Neutronics code VALE for two-dimensional triagonal (hexagonal) and three-dimensional geometries
Energy Technology Data Exchange (ETDEWEB)
Vondy, D.R.; Fowler, T.B.
1981-08-01
This report documents the computer code VALE designed to solve multigroup neutronics problems with the diffusion theory approximation to neutron transport for a triagonal arrangement of mesh points on planes in two- and three-dimensional geometry. This code parallels the VENTURE neutronics code in the local computation system, making exposure and fuel management capabilities available. It uses and generates interface data files adopted in the cooperative effort sponsored by Reactor Physics RRT Division of the US DOE. The programming in FORTRAN is straightforward, although data is transferred in blocks between auxiliary storage devices and main core, and direct access schemes are used. The size of problems which can be handled is essentially limited only by cost of calculation since the arrays are variably dimensioned. The memory requirement is held down while data transfer during iteration is increased only as necessary with problem size. There is provision for the more common boundary conditions including the repeating boundary, 180/sup 0/ rotational symmetry, and the rotational symmetry conditions for the 30/sup 0/, 60/sup 0/, and 120/sup 0/ triangular grids on planes. A variety of types of problems may be solved: the usual neutron flux eignevalue problem, or a direct criticality search on the buckling, on a reciprocal velocity absorber (prompt mode), or on nuclide concentrations. The adjoint problem and fixed source problem may be solved, as well as the dominating higher harmonic, or the importance problem for an arbitrary fixed source.
Rathjen, K. A.
1977-01-01
A digital computer code CAVE (Conduction Analysis Via Eigenvalues), which finds application in the analysis of two dimensional transient heating of hypersonic vehicles is described. The CAVE is written in FORTRAN 4 and is operational on both IBM 360-67 and CDC 6600 computers. The method of solution is a hybrid analytical numerical technique that is inherently stable permitting large time steps even with the best of conductors having the finest of mesh size. The aerodynamic heating boundary conditions are calculated by the code based on the input flight trajectory or can optionally be calculated external to the code and then entered as input data. The code computes the network conduction and convection links, as well as capacitance values, given basic geometrical and mesh sizes, for four generations (leading edges, cooled panels, X-24C structure and slabs). Input and output formats are presented and explained. Sample problems are included. A brief summary of the hybrid analytical-numerical technique, which utilizes eigenvalues (thermal frequencies) and eigenvectors (thermal mode vectors) is given along with aerodynamic heating equations that have been incorporated in the code and flow charts.
Malo, Sergio; Fateri, Sina; Livadas, Makis; Mares, Cristinel; Gan, Tat-Hean
2017-07-01
Ultrasonic guided waves testing is a technique successfully used in many industrial scenarios worldwide. For many complex applications, the dispersive nature and multimode behavior of the technique still poses a challenge for correct defect detection capabilities. In order to improve the performance of the guided waves, a 2-D compressed pulse analysis is presented in this paper. This novel technique combines the use of pulse compression and dispersion compensation in order to improve the signal-to-noise ratio (SNR) and temporal-spatial resolution of the signals. The ability of the technique to discriminate different wave modes is also highlighted. In addition, an iterative algorithm is developed to identify the wave modes of interest using adaptive peak detection to enable automatic wave mode discrimination. The employed algorithm is developed in order to pave the way for further in situ applications. The performance of Barker-coded and chirp waveforms is studied in a multimodal scenario where longitudinal and flexural wave packets are superposed. The technique is tested in both synthetic and experimental conditions. The enhancements in SNR and temporal resolution are quantified as well as their ability to accurately calculate the propagation distance for different wave modes.
二维码标准与检测质量的研究%Research of Two-dimensional Code Standard and Test Quality
Institute of Scientific and Technical Information of China (English)
严风
2016-01-01
二维码质量是二维码技术应用的关键因素，针对我国对二维码标准和质量研究的成熟度远远低于一维码的现状，文中对二维码标准和主要质量指标“符号等级”进行深入研究，探讨层排式和矩阵式二维条码符号的符号等级与印刷质量评判以及相关参数指标对符号等级的影响，旨在提高二维码印制质量，促进二维码技术推广应用。%The two-dimensional code quality is a key factor in the application of two-dimensional code technology. In view of the situation that the research maturity of the standard and the quality on two-dimensional code is far below one-dimensional code. The article makes a deep study about the two-dimensional code standard and the main quality index of "symbol level".In order to improve two-dimensional code printing quality and promote the popularization and application of two-dimensional code technology,the article also discusses the inlfuence of line type and matrix two-dimensional bar code symbol level on printing quality evaluation,as well as the inlfuence of relative parameters on the symbol level.
Bassetto, A; Torrielli, A
2002-01-01
Commutative Yang-Mills theories in 1+1 dimensions exhibit an interesting interplay between geometrical properties and U(N) gauge structures: in the exact expression of a Wilson loop with $n$ windings a non trivial scaling intertwines $n$ and $N$. In the non-commutative case the interplay becomes tighter owing to the merging of space-time and ``internal'' symmetries in a larger group $U(\\infty)$. We perform an explicit perturbative calculation of such a loop up to ${\\cal O}(g^6)$; rather surprisingly, we find that in the contribution from the crossed graphs (the genuine non-commutative terms) the scaling we mentioned occurs for large $n$ and $N$ in the limit of maximal non-commutativity $\\theta=\\infty$. We present arguments in favour of the persistence of such a scaling at any perturbative order and succeed in summing the related perturbative series.
Directory of Open Access Journals (Sweden)
Puskar Raj SHARMA
2012-01-01
Full Text Available Aim of the paper is to investigate solution of twodimensional linear parabolic partial differential equation with non-local boundary conditions using Homotopy Perturbation Method (HPM. This method is not only reliable in obtaining solution of such problems in series form with high accuracy but it also guarantees considerable saving of the calculation volume and time as compared to other methods. The application of the method has been illustrated through an example
Torrielli, Alessandro
2003-01-01
The results of our research on noncommutative perturbative quantum field theory and its relation to string theory are exposed with details. 1) We give an introduction to noncommutative quantum field theory and its derivation from open string theory in an antisymmetric background. 2) We perform a perturbative Wilson loop calculation for 2D NCYM. We compare the LCG results for the WML and the PV prescription. With WML the loop is well-defined and regular in the commutative limit. With PV the result is singular. This is intriguing: in the commutative theory their difference is related to topological excitations, moreover PV provides a point-like potential. 3) Commutative 2D YM exhibits an interplay between geometrical and U(N) gauge properties: in the exact expression of a Wilson loop with n windings a scaling intertwines n and N. In the NC case the interplay becomes tighter due to the merging of space-time and ``internal'' symmetries. Surprisingly, in our up to O(g^6) (and beyond) crossed graphs calculations the scaling we mentioned occurs for large n, N and theta. 4) We discuss the breakdown of perturbative unitarity of noncommutative electric-type QFT in the light of strings. We consider the analytic structure of string loop two-point functions suitably continuing them off-shell, and then study the Seiberg-Witten limit. In this way we pick up how the unphysical tachyonic branch cut appears in the NC field theory.
Torrielli, A
2003-01-01
The results of our research on noncommutative perturbative quantum field theory and its relation to string theory are exposed with details. 1) We give an introduction to noncommutative quantum field theory and its derivation from open string theory in an antisymmetric background. 2) We perform a perturbative Wilson loop calculation for 2D NCYM. We compare the LCG results for the WML and the PV prescription. With WML the loop is well-defined and regular in the commutative limit. With PV the result is singular. This is intriguing: in the commutative theory their difference is related to topological excitations, moreover PV provides a point-like potential. 3) Commutative 2D YM exhibits an interplay between geometrical and U(N) gauge properties: in the exact expression of a Wilson loop with n windings a scaling intertwines n and N. In the NC case the interplay becomes tighter due to the merging of space-time and ``internal'' symmetries. Surprisingly, in our up to O(g^6) (and beyond) crossed graphs calculations th...
Application of two-dimensional code in mobile education%二维码在移动学习中的应用
Institute of Scientific and Technical Information of China (English)
吕海燕; 刘瑞儒; 霍惠芳
2013-01-01
随着3G时代的到来以及手机、平板电脑等移动终端的普及,使得二维码这种新的信息传递方式迅速发展,目前已被大量应用于商业领域,但在教育领域应用很少.文章主要介绍了二维码的相关知识,并结合当前一些商用二维码软件,以手机终端为例,构建了一个基于二维码的移动教育案例.同时,介绍了相关操作步骤及使用注意事项.%With the coming of the 3G era and the popularity of mobile terminals such as mobile phones and tablet PCs, two-dimensional code, the new mode of information transmission, is developing rapidly. However, this technology is rarely applied in education. This article briefly introduces related knowledge of two-dimensional code, and constructs a mobile education case based on the two-dimensional code by combining current business two-dimensional code software and taking mobile phone terminal as an example. The article also introduces the operation steps and related precautions when it is used.
Shinzawa, Hideyuki; Murakami, Takurou N.; Nishida, Masakazu; Kanematsu, Wataru; Noda, Isao
2014-07-01
Multiple-perturbation two-dimensional (2D) correlation spectroscopy was applied to sets of near-infrared (NIR) imaging data of polylactic acid (PLA) nanocomposite samples undergoing UV degradation. Incorporation of clay nanoparticles substantially lowers the surface free energy barrier for the nucleation of PLA and eventually increases the frequency of the spontaneous nucleation of PLA crystals. Thus, when exposed to external stimuli such as UV light, PLA nanocomposite may show different structure alternation depending on the clay dispersion. Multiple-perturbation 2D correlation analysis of the PLA nanocomposite samples revealed different spatial variation between crystalline and amorphous structure of PLA, and the phenomenon especially becomes acute in the region where the clay particles are coagulated. The incorporation of the clay leads to the cleavage-induced crystallization of PLA when the sample is subjected to the UV light. The additional development of the ordered crystalline structure then works favorably to restrict the initial degradation of the polymer, providing the delay in the weight loss of the PLA.
Energy Technology Data Exchange (ETDEWEB)
Jost, G.; Tran, T.M.; Appert, K. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Wuethrich, S. [CRAY Research, PATP/PSE, EPFL, Lausanne (Switzerland)
1996-12-01
A two-dimensional PIC code aimed at the investigation of electron-cyclotron beam instabilities in gyrotrons and their effects on the beam quality is presented. The code is based on recently developed techniques for handling charge conservation and open boundaries and uses an electromagnetic field which is decomposed in its transverse magnetic (TM) and electric (TE) components. The code has been implemented on the massively parallel computer CRAY T3D, and on the CRAY Y-MP. (author) figs., tabs., refs.
Energy Technology Data Exchange (ETDEWEB)
Vilardy, Juan M; Giacometto, F; Torres, C O; Mattos, L, E-mail: vilardy.juan@unicesar.edu.co [Laboratorio de Optica e Informatica, Universidad Popular del Cesar, Sede balneario Hurtado, Valledupar, Cesar (Colombia)
2011-01-01
The two-dimensional Fast Fourier Transform (FFT 2D) is an essential tool in the two-dimensional discrete signals analysis and processing, which allows developing a large number of applications. This article shows the description and synthesis in VHDL code of the FFT 2D with fixed point binary representation using the programming tool Simulink HDL Coder of Matlab; showing a quick and easy way to handle overflow, underflow and the creation registers, adders and multipliers of complex data in VHDL and as well as the generation of test bench for verification of the codes generated in the ModelSim tool. The main objective of development of the hardware architecture of the FFT 2D focuses on the subsequent completion of the following operations applied to images: frequency filtering, convolution and correlation. The description and synthesis of the hardware architecture uses the XC3S1200E family Spartan 3E FPGA from Xilinx Manufacturer.
Applications of two-dimensional code in academic journals%科技期刊二维码的应用情况分析
Institute of Scientific and Technical Information of China (English)
杨郁霞
2013-01-01
Applications of two-dimensional code in academic journals are explored from two aspects:reading and being read.Meanwhile the possible problems and solutions involved in editors,authors and readers,technology and standard drafting in the applications of two-dimensional code in academic journals are put forward.%二维码的应用分为主读和被读2类.从这2个方面分析二维码在科技期刊中的应用情况,并从编辑、作者、读者以及技术、标准的制订等方面指出二维码应用中存在的问题,提出解决问题的途径.
The Application of QR Two-dimensional Code in the Elevator Using Sign%QR二维码在电梯使用标志中的应用
Institute of Scientific and Technical Information of China (English)
王艳平; 吴爱京; 廖学春; 李春红
2014-01-01
According to the relevant requirements of the state, the anti-counterfeiting mark with two-dimensional code should be used to realize the information management in the elevator using symbol by the institute of especial equipment supervision and inspection with appropriate conditions. The selection and realization of two-dimensional code in elevator are researched in this paper, and the advantages and principle of QR two-dimensional code are briefly introduced. Then the systems to generate and print and read and recognize the elevator using symbol based on QR two-dimensional code are developed, and the reading of intelligent information and anti-counterfeit identification of elevator using symbol in the on-site inspection are realized, which are easy to query and verify the equipment information.%根据国家有关要求，有条件的检验机构应在电梯使用标志上使用二维码防伪标志，实现信息化管理。该文对电梯二维码选型及实现进行了研究，简要介绍了QR二维码的优点及原理，开发了基于QR二维码的电梯使用标志生成打印、读取识别系统，实现检验现场对电梯设备信息智能化读取及电梯使用标志防伪识别，便于检验现场查询及核实设备信息。
A Novel Automatic Algorithm of Customized Two Dimensional Code%一种个性化二维码自动生成算法
Institute of Scientific and Technical Information of China (English)
丘文峰; 王耀民; 赵云
2012-01-01
针对个性化QR码手工设计过程复杂，无法精确放置嵌入个性化图片的问题．根据QK数据存放的位置特性，修改QR码生成算法，设计一个个性化二维码自动生成算法。该算法可以设定图像前景和背景色，在QR码中央、角落、放置图像。实验表明，生成的个性化二维码可以被主流QR码识别工具识别、%According to the problem that the personalized QR code manual design process is complex, and cannot be accurately placed embedded personalized picture, for the QR data storage location characteristics, modifies the QR code generation algorithm, designs a personalized two-dimensional code automatic generation algorithm. This algorithm can set the colors of the image foreground and background, in the QR code central, corner, placing the image. Experimental result shows that the generated personalized two-dimensional code can be distinguished by mainstream QR code identification tool.
Shinzawa, Hideyuki; Awa, Kimie; Noda, Isao; Ozaki, Yukihiro
2013-02-01
Transient water absorption by cellulosic samples manufactured under varying pressure was monitored by near-infrared spectroscopy to explore the absorption behavior affected by the pressure. A substantial level of variation of the spectral features was induced by the water absorption and changes in the pressure. The detail of the spectral changes was analyzed with a multiple-perturbation, two-dimensional (2D) correlation method to determine the underlying mechanism. The 2D correlation spectra indicated that the compression of the cellulose increased the packing density of the samples, preventing the penetration of water. In addition, the compression substantially disintegrated its crystalline structure and eventually resulted in the development of inter- and intrachain hydrogen-bonded structures arising from an interaction between the water and cellulose. Consequently, the cellulose samples essentially underwent an evolutionary change in the polymer structure as well as in the packing density during the compression. This structural change, in turn, led to the seemingly complicated absorption trends, depending on the pressure.
Research and Implementation of a Secure Two-dimensional Code%安全实用的二维码研究与实现
Institute of Scientific and Technical Information of China (English)
高彦受; 许春根
2012-01-01
Two-dimensional code is carried large amounts of information in the form of pictures, to achieve the purpose of fast and convenient. So far, It is widely used in e-commerce and ticketing systems. However, two-dimensional codes is also faced with security threats such as information disclosure and information altered. Our article research the main problem faced by the two-dimensional code. For example, when we generated the QR code, we encrypt the source data to prevent information leakage. The encryption method is RC4. Finally, designed and implemented a QR code. This design will not disclose personal information and generate high efficiency. The important is application value in practice.% 二维码是将大量信息以图片的形式承载，达到快捷方便的目的，目前广泛运用于电子商务、票务系统等。然而，二维码也面临着信息泄露和信息涂改等安全威胁，文章对二维码所面临的主要问题进行了研究，以QR码为例，为防止信息泄露，在进行QR码生成时对数据进行了加密处理，主要是RC4加密，最后设计并实现了QR码的生成，该设计方案不仅不会泄露个人信息，而且生成效率很高，在实际中具有应用价值。
User's manual for EVITS: a steady state fluids code for complex two-dimensional geometries
Energy Technology Data Exchange (ETDEWEB)
Domanus, H.M.
1976-07-01
A 2-D computer code, EVITS, has been developed for estimating steady state, incompressible, isothermal flow fields in complex geometries. A vorticity-stream function formulation is used along with a model to resolve viscous effects at solid boundaries. Sufficient geometry and boundary type options are included within the code so that a large number of flow situations can be specified without modifying the program. All instructions to the code are via an input dataset. Detailed instructions for preparing the user oriented input, along with examples, are included in this users' manual.
Li, Hanshan; Lei, Zhiyong
2013-01-01
To improve projectile coordinate measurement precision in fire measurement system, this paper introduces the optical fiber coding fire measurement method and principle, sets up their measurement model, and analyzes coordinate errors by using the differential method. To study the projectile coordinate position distribution, using the mathematical statistics hypothesis method to analyze their distributing law, firing dispersion and probability of projectile shooting the object center were put under study. The results show that exponential distribution testing is relatively reasonable to ensure projectile position distribution on the given significance level. Through experimentation and calculation, the optical fiber coding fire measurement method is scientific and feasible, which can gain accurate projectile coordinate position.
二维欧拉程序中一种新的分界面跟踪技术%AN ALGORITHM FOR TRACKING INTERFACES IN TWO-DIMENSIONAL EULERIAN CODE
Institute of Scientific and Technical Information of China (English)
温万治; 恽寿榕; 张月琴
2000-01-01
A method is presented for tracking interfaces, which is MOCL (marker oncell line) employed in two-dimensional Eulerian code. To test it, fivekinds of objects with different shapes being uniform motion arenumerically simulated in a two-dimensional Eulerian hydrodynamics codethat uses the MOCL technique to track interfaces. Results show that themethod is simple and feasible.
Toroidal Energy Principle (TEP) and perturbed equilibrium code STB
Zakharov, Leonid; Hu, Di
2016-10-01
The MHD energy principle TEP is presented in terms of perturbations of the vector potential, rather than plasma displacement. This form makes TEP capable to discribe both the ideal plasmas stability and the perturbed equilibria. The functional is expressed in two terms. The first one represents the energy of magnetic field and is calculated using working equilibrium coordinate system. The second term, containing plasma displacement is expressed in the compact form using Hamada coordinates. This representation uses the same combinations of metric coefficients as in the equilibrium calculations. The STB code implements the TEP for both ideal MHD and perturbed equilibria. In the first case, it uses the matching conditions of the ideal MHD. In the second case, the 2-D equilibrium islands are introduced in order to resolve the singularity and match the solutions across the resonant surfaces Partially by (a) US DoE Contract No. DE-AC02-09-CH11466, (b) General Fusion Inc.
Directory of Open Access Journals (Sweden)
Jung-Sik Choi
2015-06-01
Full Text Available The operating characteristics of hydrogen iodide (HI decomposition for hydrogen production were investigated using the commercial computational fluid dynamics code, and various factors, such as hydrogen production, heat of reaction, and temperature distribution, were studied to compare device performance with that expected for device development. Hydrogen production increased with an increase of the surface-to-volume (STV ratio. With an increase of hydrogen production, the reaction heat increased. The internal pressure and velocity of the HI decomposer were estimated through pressure drop and reducing velocity from the preheating zone. The mass of H2O was independent of the STV ratio, whereas that of HI decreased with increasing STV ratio.
Institute of Scientific and Technical Information of China (English)
吕慧中; 蓝凤华; 李宏昌
2015-01-01
This paper introduces the color two-dimensional code on the basis of introducing the traditional black and white two-dimensional code. The two dimensional code is changed into color to provide more watermark embedding position and higher visibility. The MATLAB simulation experiment proves the feasibility of embedding the watermark information in the two-dimensional code. Based on characteristics of color two-dimensional code, this paper studies the application of digital watermark in color two-dimensional code. By embedding watermark through through R, G, B color component translation and rotation, this paper designs a watermarking algorithm based on the color two-dimensional code, which can resist geometric attacks and improve the security and practicability of two-dimensional code.%在介绍了传统黑白二维码的基础上,对彩色二维码进行了介绍.将二维码变成彩色,提供了更多的水印嵌入位置和更高的不可见性.通过Matlab仿真实验,验证了在彩色二维码中嵌入水印信息的可行性,并结合彩色二维码的特点,对数字水印在彩色二维码中的应用进行研究,采用R、G和B三种颜色分量分别平移和旋转的方法嵌入水印,设计出了一种可抵抗几何攻击的彩色二维码水印算法,提高了二维码的安全性和实用性.
Einkemmer, Lukas
2017-01-01
To optimize the geometry of airfoils for a specific application is an important engineering problem. In this context genetic algorithms have enjoyed some success as they are able to explore the search space without getting stuck in local optima. However, these algorithms require the computation of aerodynamic properties for a significant number of airfoil geometries. Consequently, for low-speed aerodynamics, panel methods are most often used as the inner solver. In this paper we evaluate the performance of such an optimization algorithm on modern accelerators (more specifically, the Intel Xeon Phi 7120 and the NVIDIA K80). For that purpose, we have implemented an optimized version of the algorithm on the CPU and Xeon Phi (based on OpenMP, vectorization, and the Intel MKL library) and on the GPU (based on CUDA and the MAGMA library). We present timing results for all codes and discuss the similarities and differences between the three implementations. Overall, we observe a speedup of approximately 2.5 for adding an Intel Xeon Phi 7120 to a dual socket workstation and a speedup between 3.4 and 3.8 for adding a NVIDIA K80 to a dual socket workstation.
Evaluation of the Intel Xeon Phi and NVIDIA K80 as accelerators for two-dimensional panel codes
Einkemmer, Lukas
2015-01-01
To predict the properties of fluid flow over a solid geometry is an important engineering problem. In many applications so-called panel methods (or boundary element methods) have become the standard approach to solve the corresponding partial differential equation. Since panel methods in two dimensions are computationally cheap, they are well suited as the inner solver in an optimization algorithm. In this paper we evaluate the performance of the Intel Xeon Phi 7120 and the NVIDIA K80 to accelerate such an optimization algorithm. For that purpose, we have implemented an optimized version of the algorithm on the CPU and Xeon Phi (based on OpenMP, vectorization, and the Intel MKL library) and on the GPU (based on CUDA and the MAGMA library). We present timing results for all codes and discuss the similarities and differences between the three implementations. Overall, we observe a speedup of approximately $2.5$ for adding a Intel Xeon Phi 7120 to a dual socket workstation and a speedup between $3$ and $3.5$ for...
Gonzalez, C. M.; Sanchez, D. A.; Yuen, D. A.; Wright, G. B.; Barnett, G. A.
2010-12-01
As computational modeling became prolific throughout the physical sciences community, newer and more efficient ways of processing large amounts of data needed to be devised. One particular method for processing such large amounts of data arose in the form of using a graphics processing unit (GPU) for calculations. Computational scientists were attracted to the GPU as a computational tool as the performance, growth, and availability of GPUs over the past decade increased. Scientists began to utilize the GPU as the sole workhorse for their brute force calculations and modeling. The GPUs, however, were not originally designed for this style of use. As a result, difficulty arose when trying to find a use for the GPU from a scientific standpoint. A lack of parallel programming routines was the main culprit behind the difficulty in programming with a GPU, but with time and a rise in popularity, NVIDIA released a proprietary architecture named Fermi. The Fermi architecture, when used in conjunction with development tools such as CUDA, allowed the programmer easier access to routines that made parallel programming with the NVIDIA GPUs an ease. This new architecture enabled the programmer full access to faster memory, double-precision support, and large amounts of global memory at their fingertips. Our model was based on using a second-order, spatially correct finite difference method and a third order Runge-Kutta time-stepping scheme for studying the 2D Rayleigh-Benard code. The code extensively used the CUBLAS routines to do the heavy linear algebra calculations. The calculations themselves were completed using a single GPU, the NVDIA C2070 Fermi, which boasts 6 GB of global memory. The overall scientific goal of our work was to apply the Tesla C2070's computing potential to achieve an onset of flow reversals as a function of increasing large Rayleigh numbers. Previous investigations were successful using a smaller grid size of 1000x1999 and a Rayleigh number of 10^9. The
A Recognition Algorithm for Highly Deformed Two-Dimensional Code%高形变二维码识别算法设计与实现
Institute of Scientific and Technical Information of China (English)
于继明; 徐楠; 陈硕
2014-01-01
针对 QR(Quick Response)二维码在高偏离拍摄角度下难以识别的问题，设计一种在高偏离拍摄角度下正确识别的算法。该算法通过对图像二值化处理、形态学处理、边缘检测、Hough 变换和射影几何变换5个步骤，实现对图像的高准确率识别，使用 java 语言环境和移动终端的 android 环境下对算法进行仿真与算法验证，并实现了通过扫描或读取二维码图像来写入、查找信息等操作。%A recognition algorithm at a highly deviated shooting angle is proposed,which can solve the puzzle of identification for QR (Quick Response)two-dimensional code in case of high-angle shooting deviation from itself.The image can be recognized with high accuracy through the method with five procedures to process the image,i.e.,binarization processing, morphological processing,edge detection,Hough transformation and projective geometry trans-formation.Then the algorithm has been simulated and evaluated by using java language envi-ronment and android mobile terminal.By scanning or reading two-dimensional code image,the i-dentification function can be realized with the algorithm.
Institute of Scientific and Technical Information of China (English)
肖菲菲; 刘真
2011-01-01
The principle of two-dimensional bar code anti-counterfeiting technology was analyzed.A plan of applying two-dimensional code anti-counterfeiting technology in variable-data printing was put forward.On the basis of experiments on generation and recognition of two-dimensional bar code,anti-counterfeiting properties of two different two-dimensional bar codes（PDF417 code and QR code） were obtained and their difference was compared.The theoretical analysis and experiment results showed that anti-counterfeiting technology based on two-dimensional bar code can be used in variable data printing,besides,different two-dimensional bar codes have different anti-counterfeiting properties;different two-dimensional bar code should be selected according to specific requirements.%分析了二维码的防伪原理,提出了在可变数据印刷中应用二维码进行防伪的方案,在完成基于可变数据印刷的二维码的生成和识别实验的基础上,设计实验比较得出了不同二维码（PDF417码与QR码）的防伪特性的差异。理论分析及实验结果表明,利用二维码对可变数据印刷进行防伪的方案是可行的,并且不同二维码的防伪特性存在差异,在实际应用中可以根据具体的要求选用不同的二维码。
Institute of Scientific and Technical Information of China (English)
徐义钊; 白瑞林; 余震虹; 吉峰
2012-01-01
为实现工业现场中Data Matrix二维条码的快速识别,提出一种基于链码跟踪、直线段提取的条码快速识别方法.首先采用Sobel算子提取图像边缘；然后基于链码跟踪方法,跟踪图像的边缘点,记录链码；接着根据快速直线段提取方法,将直线相似度低于阈值的线段剔除,结合线形连接方法合并断裂线段,并使用长度判别剔除不可靠的线段；最后结合Data Matrix二维条码的特征,定位Data Matrix二维条码.实际测试表明,该识别方法能够快速、准确地定位二维条码区域,识别正确率可达99.39％以上,具有实时性强、可靠性好等特点,满足工业现场要求.%A two-dimensional bar code recognition method based on chain code tracking and straight line segment extraction was proposed in order to realize quick identification of the Data Matrix two-dimensional bar code in the industrial field. Firstly, the Sobel operator was used to extract the edge of image. Secondly, the image edge points were tracked and chain codes were recorded based on chain code tracking method. Thirdly, line segment whose straight line similarity was below the threshold was removed with fast straight line segment extraction method. The fracture line was combined with the linear connection method and the unreliable line was excluded by length discrimination. Finally, the Data Matrix bar code was located with the characteristics of the Data Matrix two-dimensional bar code. The application test shows that the two-dimensional bar code area can be quickly and accurately located by the recognition method with the recognition rate of 99. 39%. The proposed method is ready to meet the requirements of industrial field with strong real-time ability and high reliability.
Directory of Open Access Journals (Sweden)
Jian Zhou
2016-09-01
Full Text Available Hydraulic fracturing is a useful tool for enhancing rock mass permeability for shale gas development, enhanced geothermal systems, and geological carbon sequestration by the high-pressure injection of a fracturing fluid into tight reservoir rocks. Although significant advances have been made in hydraulic fracturing theory, experiments, and numerical modeling, when it comes to the complexity of geological conditions knowledge is still limited. Mechanisms of fluid injection-induced fracture initiation and propagation should be better understood to take full advantage of hydraulic fracturing. This paper presents the development and application of discrete particle modeling based on two-dimensional particle flow code (PFC2D. Firstly, it is shown that the modeled value of the breakdown pressure for the hydraulic fracturing process is approximately equal to analytically calculated values under varied in situ stress conditions. Furthermore, a series of simulations for hydraulic fracturing in competent rock was performed to examine the influence of the in situ stress ratio, fluid injection rate, and fluid viscosity on the borehole pressure history, the geometry of hydraulic fractures, and the pore-pressure field, respectively. It was found that the hydraulic fractures in an isotropic medium always propagate parallel to the orientation of the maximum principal stress. When a high fluid injection rate is used, higher breakdown pressure is needed for fracture propagation and complex geometries of fractures can develop. When a low viscosity fluid is used, fluid can more easily penetrate from the borehole into the surrounding rock, which causes a reduction of the effective stress and leads to a lower breakdown pressure. Moreover, the geometry of the fractures is not particularly sensitive to the fluid viscosity in the approximate isotropic model.
Domański, J.; Badziak, J.; Jabloński, S.
2016-04-01
Laser-driven generation of high-energy ion beams has recently attracted considerable interest due to a variety of potential applications including proton radiography, ICF fast ignition, nuclear physics or hadron therapy. The ion beam parameters depend on both laser pulse and target parameters, and in order to produce the ion beam of properties required for a particular application the laser and target parameters must be carefully selected, and the mechanism of the ion beam generation should be well understood and controlled. Convenient and commonly used tools for studies of the ion acceleration process are particle-in-cell (PIC) codes. Using two-dimensional PIC simulations, the properties of a proton beam generated from a thin erbium hydride (ErH3) target irradiated by a 25fs laser pulse of linear or circular polarization and of intensity ranging from 1020 to 1021 W/cm2 are investigated and compared with the features of a proton beam produced from a hydrocarbon (CH) target. It has been found that using erbium hydride targets instead of hydrocarbon ones creates an opportunity to generate more compact proton beams of higher mean energy, intensity and of better collimation. This is especially true for the linear polarization of the laser beam, for which the mean proton energy, the amount of high energy protons and the intensity of the proton beam generated from the hydride target is by an order of magnitude higher than for the hydrocarbon target. For the circular polarization, the proton beam parameters are lower than those for the linear one, and the effect of target composition on the acceleration process is weaker.
Institute of Scientific and Technical Information of China (English)
蒋佳男; 王必超; 冯善武; 王化宇; 付东英
2015-01-01
Objective To manage the precious instruments in operating room using the self-made two-di-mensional code by QR two-dimensional code storage information principle. Methods Two-dimensional QR code, generated by the two-dimensional code software based on the relevant information of the required storage instru-ments edited by the office software, were pasted in the instruments for equipment management. Results The effi-ciency of equipment management using two-dimensional QR code technology was higher than that of traditional method. Conclusion Two-dimensional QR codes provide valuable benefits for the optimization of management pro-cess, data statistics, and instrument tracing, showing great convenience to equipment management in operating room.%目的：运用QR二维码存储信息原理，自制二维码对手术室贵重仪器进行管理。方法利用Office软件编辑所需存储仪器的相应信息，使二维码软件生成对应的二维码并粘贴在仪器上，进行仪器管理。结果使用QR二维码技术进行仪器管理效率明显高于传统管理效率。结论 QR二维码在优化管理流程，数据统计，仪器追踪等方面效果明显，为手术室仪器管理工作提供便捷。
Sznajd, J.
2016-12-01
The linear perturbation renormalization group (LPRG) is used to study the phase transition of the weakly coupled Ising chains with intrachain (J ) and interchain nearest-neighbor (J1) and next-nearest-neighbor (J2) interactions forming the triangular and rectangular lattices in a field. The phase diagrams with the frustration point at J2=-J1/2 for a rectangular lattice and J2=-J1 for a triangular lattice have been found. The LPRG calculations support the idea that the phase transition is always continuous except for the frustration point and is accompanied by a divergence of the specific heat. For the antiferromagnetic chains, the external field does not change substantially the shape of the phase diagram. The critical temperature is suppressed to zero according to the power law when approaching the frustration point with an exponent dependent on the value of the field.
Sznajd, J
2016-12-01
The linear perturbation renormalization group (LPRG) is used to study the phase transition of the weakly coupled Ising chains with intrachain (J) and interchain nearest-neighbor (J_{1}) and next-nearest-neighbor (J_{2}) interactions forming the triangular and rectangular lattices in a field. The phase diagrams with the frustration point at J_{2}=-J_{1}/2 for a rectangular lattice and J_{2}=-J_{1} for a triangular lattice have been found. The LPRG calculations support the idea that the phase transition is always continuous except for the frustration point and is accompanied by a divergence of the specific heat. For the antiferromagnetic chains, the external field does not change substantially the shape of the phase diagram. The critical temperature is suppressed to zero according to the power law when approaching the frustration point with an exponent dependent on the value of the field.
Energy Technology Data Exchange (ETDEWEB)
Yun, G. S.; Lee, W.; Choi, M. J.; Lee, J.; Park, H. K. [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Domier, C. W.; Luhmann, N. C. Jr. [University of California at Davis, Davis, California 95616 (United States); Tobias, B. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Donne, A. J. H. [FOM-Institute for Plasma Physics Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Einhoven University of Technology, 5600 MB Einhoven (Netherlands); Lee, J. H.; Jeon, Y. M.; Yoon, S. W. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Collaboration: KSTAR Team
2012-05-15
The temporal evolution of edge-localized modes (ELMs) has been studied using a 2-D electron cyclotron emission imaging system in the KSTAR tokamak. The ELMs are observed to evolve in three distinctive stages: the initial linear growth of multiple filamentary structures having a net poloidal rotation, the interim state of regularly spaced saturated filaments, and the final crash through a short transient phase characterized by abrupt changes in the relative amplitudes and distance among filaments. The crash phase, typically consisted of multiple bursts of a single filament, involves a complex dynamics, poloidal elongation of the bursting filament, development of a fingerlike bulge, and fast localized burst through the finger. Substantial alterations of the ELM dynamics, such as mode number, poloidal rotation, and crash time scale, have been observed under external magnetic perturbations with the toroidal mode number n= 1.
Institute of Scientific and Technical Information of China (English)
何旭凤; 金镇; 颜凯利; 钟倩茹; 赵一飞
2015-01-01
Two-dimensional code as one of the entrances of the Mobile Internet Marketing, connecting online with offline. It becomes an effective platform for information dissemination and communication between businesses and consumers, and forms a marketing mode of O2O. Based on the relevant theory of information dissemination, the research status of the two-dimensional code marketing is analyzed, and the two-dimensional code marketing model is designed, and the application of two-dimensional code marketing in real life is described.%二维码作为移动互联网营销的入口之一，连接线上与线下，成为商家与消费者之间信息传播与交流的有效平台，并形成O2O的营销模式。基于信息传播的相关理论，分析二维码营销的研究现状，设计并提出二维码营销模型，并阐述二维码营销在现实生活中的应用。
浅谈设计型二维码在品牌识别系统中的应用%Application of Design Two-dimensional Code in Brand Recognition System
Institute of Scientific and Technical Information of China (English)
高立伟
2013-01-01
With the continuous development of image recognition technology and wireless communication technology, two-dimensional code technology has a wide range of application in the new media such as mobile phone. Creative two-dimensional code with high reorganization is significant to the improvement of enterprise's brand image the increase of consumer's attention and fancy to brand for brand design and communication. The current design of two-dimensional code in our country is made of the simple black and white squares, and it is more and more difficult to meet the increasing demand of consumer, and is difficult to make the brand stand out form the general two-dimensional code design. The paper puts forward that the new design philosophy that changing line and color, adding drawing and graphics elements for increasing the design sense of two-dimensional code and improving its reorganization and affinity, and states the necessity of the two-dimensional code with design sense and its development trend in order to promote the progress of two-dimensional code design.%随着无线通信技术、图像识别技术的不断发展，二维码技术在手机等新媒体上的应用也更为广泛，在品牌设计与传播中，充满创意、辨识度较高的二维码对提升企业品牌形象，增加消费者对于品牌的关注和喜爱具有重要意义。然而当前我国的二维码设计大多还停留在在简单的黑白格子上，越来越难以满足消费者日益增大的求新求异需求，难以让品牌在同一的二维码设计中脱颖而出，因此本文提出在传统二维码中改变线条、颜色，加入手绘、图形等元素，增加二维码的设计感，提升其辨别度和亲和度，并对发展这种有设计感的二维码的必要性及其未来发展趋势做了阐述，以期促进我国二维码设计的进步。
Nakamura, Kaoru; Higuchi, Sadao; Ohnuma, Toshiharu
2016-03-01
Using density functional perturbation theory, we investigated the effect of various substitutional dopant elements and in-plane strain on the piezoelectric properties of ZnO. The piezoelectric stress constant e33 of doped ZnO was found to depend on the formal charge of the substitutional dopant. By decomposing the piezoelectric stress constant e33 into the individual atomic contributions, the change in the piezoelectric properties was found to originate from a change in the coupling between the atomic displacement and the strain. Furthermore, we found that in-plane tensile strain along the a axis, which is specific to the thin film, can enhance the piezoelectric constant of ZnO. A phase transition from wurtzite to h-BN-type structure was found to occur with increasing in-plane tensile. The piezoelectric strain constant d33 was predicted to reach ˜200 pC/N for 2.78 at. % V-substituted ZnO at 5.5% in-plane strain, just before the phase transition. These theoretical results suggest that the piezoelectric constant of ZnO can be enhanced by controlling the in-plane strain via selection of the substrate material and dopant element.
Xiao, Yun; Gong, Yonghui; Lv, Yanling; Lan, Yujia; Hu, Jing; Li, Feng; Xu, Jinyuan; Bai, Jing; Deng, Yulan; Liu, Ling; Zhang, Guanxiong; Yu, Fulong; Li, Xia
2015-06-03
Genome-wide transcriptome profiling after gene perturbation is a powerful means of elucidating gene functional mechanisms in diverse contexts. The comprehensive collection and analysis of the resulting transcriptome profiles would help to systematically characterize context-dependent gene functional mechanisms and conduct experiments in biomedical research. To this end, we collected and curated over 3000 transcriptome profiles in human and mouse from diverse gene perturbation experiments, which involved 1585 different perturbed genes (microRNAs, lncRNAs and protein-coding genes) across 1170 different cell lines/tissues. For each profile, we identified differential genes and their associated functions and pathways, constructed perturbation networks, predicted transcription regulation and cancer/drug associations, and assessed cooperative perturbed genes. Based on these transcriptome analyses, the Gene Perturbation Atlas (GPA) can be used to detect (i) novel or cell-specific functions and pathways affected by perturbed genes, (ii) protein interactions and regulatory cascades affected by perturbed genes, and (iii) perturbed gene-mediated cooperative effects. The GPA is a user-friendly database to support the rapid searching and exploration of gene perturbations. Particularly, we visualized functional effects of perturbed genes from multiple perspectives. In summary, the GPA is a valuable resource for characterizing gene functions and regulatory mechanisms after single-gene perturbations. The GPA is freely accessible at http://biocc.hrbmu.edu.cn/GPA/.
Hallo, L.; Olazabal-Loumé, M.; Maire, P. H.; Breil, J.; Morse, R.-L.; Schurtz, G.
2006-06-01
This paper deals with ablation front instabilities simulations in the context of direct drive ICF. A simplified DT target, representative of realistic target on LIL is considered. We describe here two numerical approaches: the linear perturbation method using the perturbation codes Perle (planar) and Pansy (spherical) and the direct simulation method using our Bi-dimensional hydrodynamic code Chic. Numerical solutions are shown to converge, in good agreement with analytical models.
Institute of Scientific and Technical Information of China (English)
姚立; 刘幺和
2012-01-01
GPS positioning and two-dimensional bar code scanning system based on ARM is presented, using the linux operating system and the associated software is provided. System can tin ly locate the positon of the goods on the transporting way and timely read the infor-mation in the two-dimensional code of the goods. Thereby increasing the efficiency of the system.%文章提出了一种以嵌入式ARM为核心,以GPS定位和二维条码扫描为基础的系统,采用Linux操作系统,并给出了相关的软件程序设计.系统可以在物品运输的途中实时的定位,并且还可以实时的了解物品上二维码的信息,从而提高了系统的效率.
Institute of Scientific and Technical Information of China (English)
滕旭
2013-01-01
In other countries ,two-dimensional code has been common for document management ,but because its encoding technology is mature ,criminals can be forged .Using pseudo fingerprint key feature encryption of two-dimensional code technology program ,achieves a"witness identity"issue ,and has an important significance for document management base on two-dimensional code .%二维条码用于证件管理在国外已经十分常见，但由于二维码的编解码技术已经非常成熟，很容易被不法分子伪造。提出了利用伪指纹特征密钥加密二维条码的技术方案，实现了“人证同一性”问题，对基于二维码的证件管理具有重要的现实意义。
Institute of Scientific and Technical Information of China (English)
刘金元; 陆野; 汪天睿
2016-01-01
This paper expounds the present situation of the two -dimensional code technology of power supplies in settlement,then explore the specific application of two-dimensional code technology in the related business process,finally the two-dimensional code technology in the material balance the next step in the direction of the application,to further improve the electric power material has an important guiding significance to the settlement system.%文中首先阐述了电力物资结算中二维码技术应用的现状，其次探索了二维码技术在相关业务流程中的具体应用，最后提出了二维码技术在物资结算中的下一步应用方向，对进一步完善电力物资结算体系具有重要的指导意义。
Implement of Product Secret Key Two-Dimensional Code Based on Unity 3D%基于Unity 3D的产品秘钥二维码实现
Institute of Scientific and Technical Information of China (English)
倪莹莹; 王晓峰; 丁小未
2016-01-01
With the development of computer technology and the rapid rise of the mobile Internet, two-dimensional code, as an automatic identifica-tion technology, is widely applied in various fields. For many software products with their own activate the secret key to maintain the copyright, puts forward to use Unity 3D to perform the client implementation, explores a new method two-dimensional code to realize the activation of the secret key. The experimental results show that, compared with the traditional activation methods, two-dimensional code is more convenient and quick, to some extent, it is of certain practical value.%随着计算机技术的发展以及移动互联网的迅速崛起，二维码作为自动识别技术广泛应用于各个领域。针对不少软件产品通过激活秘钥维护版权的问题，提出利用Unity 3D作为客户端，探索用二维码作为激活秘钥激活产品的新方法。实验结果表明，与传统激活方式相比，二维码作为激活秘钥更方便快捷，具有一定的实用价值。
PYESSENCE: Generalized Coupled Quintessence Linear Perturbation Python Code
Leithes, Alexander
2016-09-01
PYESSENCE evolves linearly perturbed coupled quintessence models with multiple (cold dark matter) CDM fluid species and multiple DE (dark energy) scalar fields, and can be used to generate quantities such as the growth factor of large scale structure for any coupled quintessence model with an arbitrary number of fields and fluids and arbitrary couplings.
Institute of Scientific and Technical Information of China (English)
晏燕; 王大程; 王前前; 孙婷婷
2012-01-01
In order to reduce the waste of papers used for printing admission tickets for all kinds of examinations and avoid the problem that two-dimensional bar code cannot carry certificate images of high quality, a two-dimensional bar code examination information system was designed and realized based on QR code. In this system a half-on-line and half-off-line method was used to provide major functions such as information gathering of candidates, arrangement of examination information, generation of electronic admission tickets with two dimensional bar code, and identification of examination information. It could not only save the paper resources but also realize triple-sided united authentication among candidates, information of electronic admission tickets, and database of candidate information.%为了减少各类考试中纸质准考证件造成的资源浪费,同时避免二维码无法承载高质量证件图像的难题,设计并实现了基于QR码的二维码考务信息系统.采用半离线半在线的方式提供考生信息采集、考务信息安排、二维码电子准考凭证生成和考务信息识别等主要功能,不但可以节约纸张资源,还可以实现参加考试人员与电子凭证信息和考生信息数据库之间的三方联合认证.
基于FPGA快速二维DCT图像编码结构%FPGA Rapid Two-dimensional DCT Image Coding Structure
Institute of Scientific and Technical Information of China (English)
龙飞; 李良荣; 李绪诚
2012-01-01
本文提出了一种二维DCT快速算法的FPGA实现结构,采用行列分解算法将二维DCT分解成两个一维DCT和一个转置缓冲器组成的结构,其中一雏DCT借鉴Arai DCT算法,并采取了FPGA特有的并行的流水线技术,该结构极大减少了加法器和乘法器的数量,节省了计算时间.该结构的特点是高数据吞吐率、硬件资源消耗少,功耗低.实验结果证明了二维DCT核设计的正确性,适合图像的实时处理.%In this paper, a two-dimensional DCT fast algorithm for FPGA implementation structure. Decomposition algorithm using the line-column, 2D-DCT is broken down into the structure of two 1D-DCT and a transpose buffer, and 1D-DCT is learn from Arai DCT algorithm, and mining is indeed a unique parallel pipeline technique in FPGA. The structure greatly reduces the adder and multiplier is the number, to save calculation time. The structure is characterized by high data throughput, the hardware resource consumption, low power consumption. The experimental results show the correctness of the two-dimensional DCT core design, suitable for real-time processing of the image.
Osserman, Robert
2011-01-01
The basic component of several-variable calculus, two-dimensional calculus is vital to mastery of the broader field. This extensive treatment of the subject offers the advantage of a thorough integration of linear algebra and materials, which aids readers in the development of geometric intuition. An introductory chapter presents background information on vectors in the plane, plane curves, and functions of two variables. Subsequent chapters address differentiation, transformations, and integration. Each chapter concludes with problem sets, and answers to selected exercises appear at the end o
Juday, Richard D. (Inventor)
1992-01-01
A two-dimensional vernier scale is disclosed utilizing a cartesian grid on one plate member with a polar grid on an overlying transparent plate member. The polar grid has multiple concentric circles at a fractional spacing of the spacing of the cartesian grid lines. By locating the center of the polar grid on a location on the cartesian grid, interpolation can be made of both the X and Y fractional relationship to the cartesian grid by noting which circles coincide with a cartesian grid line for the X and Y direction.
Energy Technology Data Exchange (ETDEWEB)
Hallo, L.; Olazabal-Loume, M.; Maire, P.H.; Breil, J.; Schurtz, G. [CELIA, 33 - Talence (France); Morse, R.L. [Arizona Univ., Dept. of Nuclear Engineering, Tucson (United States)
2006-06-15
This paper deals with ablation front instabilities simulations in the context of direct drive inertial confinement fusion. A simplified deuterium-tritium target, representative of realistic target on LIL (laser integration line at Megajoule laser facility) is considered. We describe here two numerical approaches: the linear perturbation method using the perturbation codes Perle (planar) and Pansy (spherical) and the direct simulation method using our bi-dimensional hydrodynamic code Chic. Our work shows a good behaviour of all methods even for large wavenumbers during the acceleration phase of the ablation front. We also point out a good agreement between model and numerical predictions at ablation front during the shock wave transit.
PYESSENCE - Generalised Coupled Quintessence Linear Perturbation Python Code - User Guide
Leithes, Alexander
2016-01-01
This paper is a guide to the installation and use of the Python package PYESSENCE. PYESSENCE is designed to evolve linear perturbations to Coupled Quintessence models with a arbitrary number of cold dark matter (CDM) fluids and dark energy (DE) scalar fields as dictated by a given model. The equations are sufficiently general to allow for more exotic dark matter with a non-zero equation of state. Several example uses are included in order to demonstrate typical functionality to the potential user. PYESSENCE is released under an open source modified BSD license and is available on Bitbucket.
Energy Technology Data Exchange (ETDEWEB)
Hummel, D.W.; Langton, S.E.; Ball, M.R.; Novog, D.R.; Buijs, A., E-mail: hummeld@mcmaster.ca [McMaster Univ., Hamilton, Ontario (Canada)
2013-07-01
Discrepancies have been observed among a number of recent reactor physics studies in support of the PT-SCWR pre-conceptual design, including differences in lattice-level predictions of infinite neutron multiplication factor, coolant void reactivity, and radial power profile. As a first step to resolving these discrepancies, a lattice-level benchmark problem was designed based on the 78-element plutonium-thorium PT-SCWR fuel design under a set of prescribed local conditions. This benchmark problem was modeled with a suite of both deterministic and Monte Carlo neutron transport codes. The results of these models are presented here as the basis of a code-to-code comparison. (author)
Two-dimensional optical spectroscopy
Cho, Minhaeng
2009-01-01
Discusses the principles and applications of two-dimensional vibrational and optical spectroscopy techniques. This book provides an account of basic theory required for an understanding of two-dimensional vibrational and electronic spectroscopy.
Reichert, R, S.; Biringen, S.; Howard, J. E.
1999-01-01
LINER is a system of Fortran 77 codes which performs a 2D analysis of acoustic wave propagation and noise suppression in a rectangular channel with a continuous liner at the top wall. This new implementation is designed to streamline the usage of the several codes making up LINER, resulting in a useful design tool. Major input parameters are placed in two main data files, input.inc and nurn.prm. Output data appear in the form of ASCII files as well as a choice of GNUPLOT graphs. Section 2 briefly describes the physical model. Section 3 discusses the numerical methods; Section 4 gives a detailed account of program usage, including input formats and graphical options. A sample run is also provided. Finally, Section 5 briefly describes the individual program files.
Application of QR Two-dimensional Code in Iinternational Project Logistics%QR二维码在国际工程项目物流的应用初探
Institute of Scientific and Technical Information of China (English)
朱艳平
2016-01-01
Aiming at the problems encountered in international engineering project regarding the tracking and management of logistics information,this paper discusses the demand analysis,and then establishes the QR two dimensional code element design,generation and use of methods and processes in the international engineering project logistics management.At last,as per an actual case,this paper proposes operational plans and suggestions for the application of the two -dimensional bar code technology in the international project logistics implementation and management.%针对国际工程项目在物流信息化追踪和管理中遇到的问题，文中论述了需求分析，构建了应用于国际工程项目物流的QR二维码的要素设计、生成及使用方法和流程，结合参与管理项目的实际案例，为二维码技术在国际工程项目物流实施和管理中的应用提出了具有可操作性的方案和建议。
Two dimensional structural analysis of reactor fuel element claddings due to local effects
Energy Technology Data Exchange (ETDEWEB)
Karimi, R; Wolf, L
1978-04-01
Two dimensional thermoelastic and inelastic stresses and deformation of typical LWR (PWR) and LMFBR (CRBR) claddings are evaluated by utilizing the following codes, for (1) Thermoelastic analysis (a) STRESS Code (b) SEGPIPE Code (2) Thermoinelastic analysis (a) Modified version of the GOGO code (b) One dimensional GRO-II code. The primary objective of this study is to analyze the effect of various local perturbations in the clad temperature field, namely eccentrically mounted fuel pellet, clad ovality, power tilt across the fuel and clad-coolant heat transfer variation on the cladding stress and deformation. In view of the fact that the thermoelastic analysis is always the first logical choice entering the structural field, it was decided to start the analysis with the two dimensional codes such as STRESS and SEGPIPE. Later, in order to assess the validity and compare the thermoelastic results to those obtained for actual reactor conditions, a two dimensional code, namely a modified version of the GOGO code, was used to account for inelastic effects such as irradiation and thermal creep and swelling in the evaluation. The comparison of thermoelastic and inelastic results shows that the former can be used effectively to analyze LWR fuel pin over 350 hours of lifetime under the most adverse condition and 500 hours of lifetime for an LMFBR fuel pin. Beyond that the inelastic solution must be used. The impact of the individual thermal perturbation and combinations thereof upon the structural quantity is also shown. Finally, the effect of rod displacement on the two dimensional thermal and structural quantities of the LMFBR fuel pin cladding is analyzed.
Directory of Open Access Journals (Sweden)
Szymkiewicz Adam
2015-09-01
Full Text Available Flow in unsaturated porous media is commonly described by the Richards equation. This equation is strongly nonlinear due to interrelationships between water pressure head (negative in unsaturated conditions, water content and hydraulic conductivity. The accuracy of numerical solution of the Richards equation often depends on the method used to estimate average hydraulic conductivity between neighbouring nodes or cells of the numerical grid. The present paper discusses application of the computer simulation code VS2DI to three test problems concerning infiltration into an initially dry medium, using various methods for inter-cell conductivity calculation (arithmetic mean, geometric mean and upstream weighting. It is shown that the influence of the averaging method can be very large for coarse grid, but that it diminishes as cell size decreases. Overall, the arithmetic average produced the most reliable results for coarse grids. Moreover, the difference between results obtained with various methods is a convenient indicator of the adequacy of grid refinement.
Szymkiewicz, Adam; Tisler, Witold; Burzyński, Kazimierz
2015-09-01
Flow in unsaturated porous media is commonly described by the Richards equation. This equation is strongly nonlinear due to interrelationships between water pressure head (negative in unsaturated conditions), water content and hydraulic conductivity. The accuracy of numerical solution of the Richards equation often depends on the method used to estimate average hydraulic conductivity between neighbouring nodes or cells of the numerical grid. The present paper discusses application of the computer simulation code VS2DI to three test problems concerning infiltration into an initially dry medium, using various methods for inter-cell conductivity calculation (arithmetic mean, geometric mean and upstream weighting). It is shown that the influence of the averaging method can be very large for coarse grid, but that it diminishes as cell size decreases. Overall, the arithmetic average produced the most reliable results for coarse grids. Moreover, the difference between results obtained with various methods is a convenient indicator of the adequacy of grid refinement.
Institute of Scientific and Technical Information of China (English)
徐任弘; 曾武
2016-01-01
随着移动通信技术的发展，基于移动终端的自动识别技术已经成为研究热点。二维码技术是一种信息存储，传递和识别防伪技术，已经融入到了人们的日常应用中。本文研究了基于Android平台的生物特征信息及其二维码的生成识别应用技术的开发技术，并将二维码和移动终端结合，该系统开发研究对身份信息防伪及存储方面有重要意义。%With the develop of mobile communication technology, the technology of identification based on the mobile terminal has become a frontier subject, as a new information storage, transmission and identification technology, the two-dimensional code has been integrated into the social life. In this paper, an identification and security system is designed and developed based on the Android platform of mobile terminal. Combined the mobile terminal and two-dimensional, the research of this system has important significance in the security and storage of identity information.
The characters of nonlinear vibration in the two-dimensional discrete monoatomic lattice
Institute of Scientific and Technical Information of China (English)
XU Quan; TIAN Qiang
2005-01-01
The two-dimensional discrete monoatomic lattice is analyzed. Taking nearest-neighbor interaction into account, the characters of the nonlinear vibration in two-dimensional discrete monoatomic lattice are described by the two-dimensional cubic nonlinear Schrodinger equation. Considering the quartic nonlinear potential, the two-dimensional discrete-soliton trains and the solutions perturbed by the neck mode are presented.
Thebault, Philippe
2011-01-01
Debris discs are traditionally studied using two distinct types of numerical models: statistical particle-in-a-box codes to study their collisional and size distribution evolution, and dynamical N-body models to study their spatial structure. The absence of collisions from N-body codes is in particular a major shortcoming, as collisional processes are expected to significantly alter the results obtained from pure N-body runs. We present a new numerical model, to study the spatial structure of perturbed debris discs at dynamical and collisional steady-state. We focus on the competing effects between gravitational perturbations by a massive body (planet or star), collisional production of small grains, and radiation pressure placing these grains in possibly dynamically unstable regions. We consider a disc of parent bodies at dynamical steady-state, from which small radiation-pressure-affected grains are released in a series of runs, each corresponding to a different orbital position of the perturber, where part...
Institute of Scientific and Technical Information of China (English)
朱雯晶; 夏翠娟
2012-01-01
针对种类繁多的二维码标准，选择目前使用较普及的QR码，将上海市中心图书馆联盟各成员馆各类信息进行编辑并生成相应QR码，然后印制在“上海市中心图书馆一卡通分布图册”上，再由上海图书馆手机客户端或其他条码识别软件进行识别，即可随时获取上海市中心图书馆各成员馆基本信息，并可通过其中的地理位置信息进行导航，从而形成比较完整的移动服务应用场景。%Shanghai Library chooses the QR code as the standard to generate the two - dimensional code including all the common information of Shanghai Central Library members, then prints them on the Shanghai Central Library One - card - through map and uses Shanghai Library＇s smart- phone app or other apps to identify all the information, especially the GEO information inside the QR code. Combined with navigation apps, the users can get to the library more efficiently.
Comparison of metrics obtained with analytic perturbation theory and a numerical code
Cuchí, Javier E; Ruiz, Eduardo
2012-01-01
We compare metrics obtained through analytic perturbation theory with their numerical counterparts. The analytic solutions are computed with the CMMR post-Minkowskian and slow rotation approximation due to Cabezas et al. (2007) for an asymptotically flat stationary spacetime containing a rotating perfect fluid compact source. The same spacetime is studied with the AKM numerical multi-domain spectral code (Ansorg et al., 2002,2003). We then study their differences inside the source, near the infinity and in the matching surface, or equivalently, the global character of the analytic perturbation scheme.
Nonlinear kinetic modeling and simulations of Raman scattering in a two-dimensional geometry
Directory of Open Access Journals (Sweden)
Bénisti Didier
2013-11-01
Full Text Available In this paper, we present our nonlinear kinetic modeling of stimulated Raman scattering (SRS by the means of envelope equations, whose coefficients have been derived using a mixture of perturbative and adiabatic calculations. First examples of the numerical resolution of these envelope equations in a two-dimensional homogeneous plasma are given, and the results are compared against those of particle-in-cell (PIC simulations. These preliminary comparisons are encouraging since our envelope code provides threshold intensities consistent with those of PIC simulations while requiring computational resources reduced by 4 to 5 orders of magnitude compared to full-kinetic codes.
Institute of Scientific and Technical Information of China (English)
韩飞; 薛劭节; 宋纪恩
2016-01-01
With the in-depth work related to the construction of UHV,UHV materials by categories and specifications of various types,affecting performance supervision difficult constraints,Jiangsu province electric power company supplies the in-creasing pressure of uhv.This paper mainly by citing the concept of modern logistics management,in-depth study of the two-dimensional code technology,the use of two-dimensional code technology innovation of the effective management of UHV electric power supplies,explore the “standard”management mode,clear UHV supplies customized performance tracking process and scheme,supplemented by the development of the material performance visual tracking system,the material will be two-dimen-sional code the basic information and dynamic information display in the system,the formation of visual effect,realize the tracking of material supply,enhance UHV supply management level.%随着深入开展特高压建设相关工作以来，受特高压物资品类、规格型号繁多，履约监管难度大等制约因素影响，江苏省电力公司特高压物资供应压力日益增大。文中主要通过引用现代物流管理理念，深入研究二维码技术，创新性的运用二维码技术对电力特高压物资进行有效管理，探索“标准件”管理模式，明确特高压物资客户化履约跟踪流程及方案，同时辅以开发物资可视化履约跟踪系统，将物资二维码基础信息和动态信息展示在系统内，形成可视化效果，实现对物资供应的全程跟踪，全面提升特高压物资供应管理水平。
Institute of Scientific and Technical Information of China (English)
吉建华; 范戈
2002-01-01
A new one-dimensional optical orthogonal codes(1-D OOC) named extended hyperbolic line congruence codes(EHLC) is constructed,and its performance is analyzed.Compared with extended quadratic congruence codes(EQC),EHLC has large code cardinality,but has a little poor performances of auto-correlation and cross-correlation.Then,using EHLC for time spreading and prime sequence(PC) for wavelength hopping,a new two-dimensional optical orthogonal codes(2-D OOC)named EHLC/PC is constructed.Because the code weight of EHLC equals(p-1) and the code weight of PC equals p,selection function f(i) should be used to pick out(p-1)wavelengths from each prime sequence.At last,the performance of EHLC/PC is analyzed,and is also compared with EQC/PC.Because each wavelength within a code is different,auto-correlation of EHLC/PC equals zero.When examining the cross-correlation of EHLC/PC,authors should consider four different modes:same time spreading pattern/same wavelength hopping pattern(different sk),same time spreading pattern/different wavelength hopping pattern,different time spreading pattern/same wavelength hopping pattern,different time spreading pattern/different wavelenght hopping pattern.By using difference function and wavelength hopping pattern,it is not difficult to get the cross-correlation performances of EHLC/PC.It is shown that the cross-correlation performance of EHLC/PC is a little worse than EQC/PC,but EHLC/PC has much larger code cardinality.Moreover,EHLC/PC has shorter code length and smaller code weight,which can enhance user data rate and also can reduce the complexity of optical encoders/decoders.Therefore,EHLC/PC is suitable for massive optical code-division multiple-access(OCDMA) networks.%构造了一种扩展的双曲线性同余码(EHLC)并分析了其码字性能.用该码作为时间扩频伪随机序列和以素数码(PC)作为波长跳频伪随机序列,再构成一种新的二维光正交码EHLC/PC.然后分析了EHLC/PC码字的性能,并与EQC/PC
Institute of Scientific and Technical Information of China (English)
王晨; 司占军; 沈柯
2015-01-01
产品平面宣传广告是关系产品销售的重要环节，在产品的市场推广中起着重要的作用，而二维码作为新兴的条码存储技术使人们获取信息的方式更便捷。因此，将二维码技术应用于平面广告宣传中，以手机的平面广告为研究对象，对其使用3DS Max进行建模并在网页上实现360度实景展示，最终通过二维码技术实现广告从平面到立体的延伸，完善平面媒体在信息表达方式上的缺憾。%The product graphic advertisement is an important part of the relationship among product sales, it plays an important role in product marketing, and the QR code as the barcode emerging storage technology makes people access to information in more convenient way. Therefore, the QR code technology is applied in the graphic advertising, as the research object, mobile phone to the plane advertisement can be used with 3DS Max modeling and Realization in Webpage real 360 degree display performance, finally from the plane to three-dimensional extension acheives two-dimensional code technology, where consummate the graphic media in the form of expression of the information.
Development of a perturbation code, PERT-K, for hexagonal core geometry
Energy Technology Data Exchange (ETDEWEB)
Kim, Taek Kyum; Kim, Sang Ji; Song, Hoon; Kim, Young Il; Kim, Young Jin [Korea Atomic Energy Research Institute, Taejon (Korea)
1999-01-01
A perturbation code for hexagonal core geometry has been developed based on Nodal Expansion Method. By using relevant output files of DIF3D code, it can calculate the reactivity changes caused by perturbation in composition or/and neutron cross section libraries. The accuracy of PERT-K code has been validated by calculating the reactivity changes due to fuel composition change, the sodium void coefficients, and the sample reactivity worths of BFS-73-1 critical experiments. In the case of 10% reduction in all fuel isotopics at a assembly located in the outer core, PERT-K computation agrees with the direct computation by DIF3D within 60 pcm. The sample reactivity worths of BFS-73-1 critical experiments are predicted with PERT-K code within the experimental error bounds. For 100% sodium void occurrence at the inner core, the maximum difference of reactivity changes between PERT-K and direct DIF3D computations is less than 40 pcm. On the other hand, the same sodium void condition at the outer core leads to a difference of reactivity change greater than 400 pcm. However, as sodium voiding becomes near zero value, the difference becomes less and rapidly falls within the acceptable bound, i.e. 40 pcm. (author). 11 refs., 9 figs., 6 tabs.
Institute of Scientific and Technical Information of China (English)
钟州; 金梁; 黄开枝; 白慧卿; 易鸣
2013-01-01
该文通过分析安全编码的原理推导了安全间隙约束条件下高斯窃听信道保密速率的计算方法，并根据置信传播(Belief Propagation, BP)译码算法及其改进算法，针对基于中短码长LDPC码所设计的安全编码提出一种2维信息修正的分类归一化最小和译码算法。该算法先将输入校验节点信息绝对值分成最小值和次小值两类，然后在译码初始化时利用概率统计理论分别推导出相应的最佳归一化因子对分类后的信息进行修正。仿真结果表明，该算法在高信噪比区域的译码性能高于BP算法和归一化最小和算法，低信噪比区域误比特率迅速逼近0.5，且能减小不同安全编码速率LDPC码的安全间隙，提高了保密信息安全传输的性能。%This paper analyzes the mechanism of physical layer secrecy coding and calculates the secrecy rate for the Gaussian wiretap channel under the security gap constraint. Furthermore, a classified normalized decoding algorithm with two-dimensional information correction based on Belief Propagation (BP) algorithm and its improvements for the short and medium block length Low Density Parity Check (LDPC) based secrecy codes is presented. The algorithm first utilizes classification according to the absolute values of incoming messages in check nodes. Then it uses 2-dimensional normalization to correct the minimum and sub-minimum values. The 2-dimensional normalized factors can be calculated respectively by using probability and statistic theory in the initialization step. Simulation results show that the proposed algorithm achieves better performance than BP algorithm and normalized BP-based algorithm at the high SNR, but the bit error radio gets close to 0.5 rapidly at the low SNR. It can reduce security gap of LDPC-based secrecy codes with different secrecy rates efficiently.
Two-dimensional liquid chromatography
DEFF Research Database (Denmark)
Græsbøll, Rune
of this thesis is on online comprehensive two-dimensional liquid chromatography (online LC×LC) with reverse phase in both dimensions (online RP×RP). Since online RP×RP has not been attempted before within this research group, a significant part of this thesis consists of knowledge and experience gained...
Dirac quasinormal modes of two-dimensional charged dilatonic black holes
Energy Technology Data Exchange (ETDEWEB)
Becar, Ramon [Universidad Catolica de Temuco, Departamento de Ciencias Matematicas y Fisicas, Temuco (Chile); Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)
2014-06-15
We study charged fermionic perturbations in the background of two-dimensional charged dilatonic black holes, and we present the exact Dirac quasinormal modes. Also, we study the stability of these black holes under charged fermionic perturbations. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Vong, T.S.; Leroy, M. [CEA Vaujours-Moronvilliers, 77 - Courtry (France)
1996-12-31
In this paper, the kinetics of hot spots priming in heterogenous explosives is introduced into a 2D hydrodynamical code. The AMORC kinetics model takes into account the two priming phases (formation, firing of hot spots and combustion of grains) and is evaluated in various experimental configurations with 1D and 2D symmetries. A TATB-based composition was used for this first evaluation. (J.S.) 7 refs.
Institute of Scientific and Technical Information of China (English)
徐真
2015-01-01
随着移动通信和互联网的快速发展，O2O 营销平台模式应运而生。其后，对 O2O 平台商业模式的探索从未停歇。自2012年二维码于各行各业的广泛应用以来，其作为移动互联网的线下入口，将在诸多方面引领O2O 营销平台模式的创新，具体包括引流阶段的创新、转化阶段的创新、消费阶段的创新、反馈阶段的创新和留存阶段的创新等。并对二级码在我国的未来发展进行了展望。%With the rapid development of mobile communications and the Internet,O2O marketing platform has e-merged and the exploration of the O2O platform business model has been ever growing.In 2012,the emergence of a small black and white box opened a new way for the innovation of O2O marketing platform,which included the drainage stage innovation,the transformation stage innovation,the consumption stage innovation,the feedback phase innovation and the innovation of the retention period.This paper will discuss how the small two-dimensional code promoting the innovation of O2O marketing platform model.
基于二维码识别技术的电子签到模块设计%The Modern Check-in System Based on Two-Dimensional Bar Code
Institute of Scientific and Technical Information of China (English)
李立峰
2012-01-01
With the continuous development of the socio-economic information network technology,people increasingly rely on mobile Internet,and have much higher requirements for the mobile experience; on the other hand,another part of consumption - the merchant is also gradually looking for more innovative and efficient means to demonstrate their products and services to increase revenue. In such circumstances,the sign business model appears on the scene,people can go to merchant stores to check-in and get more promotions with handheld devices. In order to solve the consumer to sign the accurate location positioning,two-dimensional code recognition technology is used to provide a real and effective sign experience.%随着社会经济与信息网络技术的不断发展,人们对移动互联网越来越依赖,对移动体验的要求也越来越高；另一方面消费的另一环节-商户也渐渐地在寻找更加新颖快捷的技术手段来表现他们的产品及服务以增加收入.在这样的环境下,签到商业模式应运而生,人们可以通过手持设备向某地的商户门店进行签到进行互动.为了解决消费者签到位置定位不准确的问题,采取了二维码识别技术来为商家和消费者提供真实有效的签到体验.
Two dimensional unstable scar statistics.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Kotulski, Joseph Daniel; Lee, Kelvin S. H. (ITT Industries/AES Los Angeles, CA)
2006-12-01
This report examines the localization of time harmonic high frequency modal fields in two dimensional cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This paper examines the enhancements for these unstable orbits when the opposing mirrors are both convex and concave. In the latter case the construction includes the treatment of interior foci.
Juday, Richard D.
1992-01-01
Modified vernier scale gives accurate two-dimensional coordinates from maps, drawings, or cathode-ray-tube displays. Movable circular overlay rests on fixed rectangular-grid overlay. Pitch of circles nine-tenths that of grid and, for greatest accuracy, radii of circles large compared with pitch of grid. Scale enables user to interpolate between finest divisions of regularly spaced rule simply by observing which mark on auxiliary vernier rule aligns with mark on primary rule.
TreePM Method for Two-Dimensional Cosmological Simulations
Indian Academy of Sciences (India)
Suryadeep Ray
2004-09-01
We describe the two-dimensional TreePM method in this paper. The 2d TreePM code is an accurate and efficient technique to carry out large two-dimensional N-body simulations in cosmology. This hybrid code combines the 2d Barnes and Hut Tree method and the 2d Particle–Mesh method. We describe the splitting of force between the PM and the Tree parts. We also estimate error in force for a realistic configuration. Finally, we discuss some tests of the code.
Optimal excitation of two dimensional Holmboe instabilities
Constantinou, Navid C
2010-01-01
Highly stratified shear layers are rendered unstable even at high stratifications by Holmboe instabilities when the density stratification is concentrated in a small region of the shear layer. These instabilities may cause mixing in highly stratified environments. However these instabilities occur in tongues for a limited range of parameters. We perform Generalized Stability analysis of the two dimensional perturbation dynamics of an inviscid Boussinesq stratified shear layer and show that Holmboe instabilities at high Richardson numbers can be excited by their adjoints at amplitudes that are orders of magnitude larger than by introducing initially the unstable mode itself. We also determine the optimal growth that obtains for parameters for which there is no instability. We find that there is potential for large transient growth regardless of whether the background flow is exponentially stable or not and that the characteristic structure of the Holmboe instability asymptotically emerges for parameter values ...
Phonon hydrodynamics in two-dimensional materials.
Cepellotti, Andrea; Fugallo, Giorgia; Paulatto, Lorenzo; Lazzeri, Michele; Mauri, Francesco; Marzari, Nicola
2015-03-06
The conduction of heat in two dimensions displays a wealth of fascinating phenomena of key relevance to the scientific understanding and technological applications of graphene and related materials. Here, we use density-functional perturbation theory and an exact, variational solution of the Boltzmann transport equation to study fully from first-principles phonon transport and heat conductivity in graphene, boron nitride, molybdenum disulphide and the functionalized derivatives graphane and fluorographene. In all these materials, and at variance with typical three-dimensional solids, normal processes keep dominating over Umklapp scattering well-above cryogenic conditions, extending to room temperature and more. As a result, novel regimes emerge, with Poiseuille and Ziman hydrodynamics, hitherto typically confined to ultra-low temperatures, characterizing transport at ordinary conditions. Most remarkably, several of these two-dimensional materials admit wave-like heat diffusion, with second sound present at room temperature and above in graphene, boron nitride and graphane.
Two-dimensional liquid chromatography
DEFF Research Database (Denmark)
Græsbøll, Rune
Two-dimensional liquid chromatography has received increasing interest due to the rise in demand for analysis of complex chemical mixtures. Separation of complex mixtures is hard to achieve as a simple consequence of the sheer number of analytes, as these samples might contain hundreds or even...... dimensions. As a consequence of the conclusions made within this thesis, the research group has, for the time being, decided against further development of online LC×LC systems, since it was not deemed ideal for the intended application, the analysis of the polar fraction of oil. Trap-and...
Two-dimensional capillary origami
Energy Technology Data Exchange (ETDEWEB)
Brubaker, N.D., E-mail: nbrubaker@math.arizona.edu; Lega, J., E-mail: lega@math.arizona.edu
2016-01-08
We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid. - Highlights: • Full solution set of the two-dimensional capillary origami problem. • Fluid does not necessarily wet the entire plate. • Global energy approach provides exact differential equations satisfied by minimizers. • Bifurcation diagrams highlight three different regimes. • Conditions for spontaneous encapsulation are identified.
Two-dimensional quantum repeaters
Wallnöfer, J.; Zwerger, M.; Muschik, C.; Sangouard, N.; Dür, W.
2016-11-01
The endeavor to develop quantum networks gave rise to a rapidly developing field with far-reaching applications such as secure communication and the realization of distributed computing tasks. This ultimately calls for the creation of flexible multiuser structures that allow for quantum communication between arbitrary pairs of parties in the network and facilitate also multiuser applications. To address this challenge, we propose a two-dimensional quantum repeater architecture to establish long-distance entanglement shared between multiple communication partners in the presence of channel noise and imperfect local control operations. The scheme is based on the creation of self-similar multiqubit entanglement structures at growing scale, where variants of entanglement swapping and multiparty entanglement purification are combined to create high-fidelity entangled states. We show how such networks can be implemented using trapped ions in cavities.
Two-dimensional capillary origami
Brubaker, N. D.; Lega, J.
2016-01-01
We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid.
Two-dimensional cubic convolution.
Reichenbach, Stephen E; Geng, Frank
2003-01-01
The paper develops two-dimensional (2D), nonseparable, piecewise cubic convolution (PCC) for image interpolation. Traditionally, PCC has been implemented based on a one-dimensional (1D) derivation with a separable generalization to two dimensions. However, typical scenes and imaging systems are not separable, so the traditional approach is suboptimal. We develop a closed-form derivation for a two-parameter, 2D PCC kernel with support [-2,2] x [-2,2] that is constrained for continuity, smoothness, symmetry, and flat-field response. Our analyses, using several image models, including Markov random fields, demonstrate that the 2D PCC yields small improvements in interpolation fidelity over the traditional, separable approach. The constraints on the derivation can be relaxed to provide greater flexibility and performance.
Classifying Two-dimensional Hyporeductive Triple Algebras
Issa, A Nourou
2010-01-01
Two-dimensional real hyporeductive triple algebras (h.t.a.) are investigated. A classification of such algebras is presented. As a consequence, a classification of two-dimensional real Lie triple algebras (i.e. generalized Lie triple systems) and two-dimensional real Bol algebras is given.
Tracking dynamics of two-dimensional continuous attractor neural networks
Fung, C. C. Alan; Wong, K. Y. Michael; Wu, Si
2009-12-01
We introduce an analytically solvable model of two-dimensional continuous attractor neural networks (CANNs). The synaptic input and the neuronal response form Gaussian bumps in the absence of external stimuli, and enable the network to track external stimuli by its translational displacement in the two-dimensional space. Basis functions of the two-dimensional quantum harmonic oscillator in polar coordinates are introduced to describe the distortion modes of the Gaussian bump. The perturbative method is applied to analyze its dynamics. Testing the method by considering the network behavior when the external stimulus abruptly changes its position, we obtain results of the reaction time and the amplitudes of various distortion modes, with excellent agreement with simulation results.
Two-dimensional function photonic crystals
Wu, Xiang-Yao; Liu, Xiao-Jing; Liang, Yu
2016-01-01
In this paper, we have firstly proposed two-dimensional function photonic crystals, which the dielectric constants of medium columns are the functions of space coordinates $\\vec{r}$, it is different from the two-dimensional conventional photonic crystals constituting by the medium columns of dielectric constants are constants. We find the band gaps of two-dimensional function photonic crystals are different from the two-dimensional conventional photonic crystals, and when the functions form of dielectric constants are different, the band gaps structure should be changed, which can be designed into the appropriate band gaps structures by the two-dimensional function photonic crystals.
Specification of a Two-Dimensional Test Case
DEFF Research Database (Denmark)
Nielsen, Peter Vilhelm
This paper describes the geometry and other boundary conditions for a test case which can be used to test different two-dimensional CFD codes in the lEA Annex 20 work. The given supply opening is large compared with practical openings. Therefore, this geometry will reduce the need for a high number...... of grid points in the wall jet region....
Institute of Scientific and Technical Information of China (English)
李健; 杨京峰; 张成昱
2012-01-01
针对国内图书馆中地理信息的缺失,介绍条形码/二维码在国内外的研究现状,利用Android等技术,设计并实现以图书导航服务为中心的图书馆个性化服务系统,重点介绍该系统的用户需求、设计思路与功能实现。通过对应用效果的评估,认为该系统可以极大地提升图书馆的服务效率和服务质量。%Due to the lack of geographic information in national library,the paper introduces the research of bar code and two-dimensional bar code,using Android and other technology,designs and realizes library personalized services system which is based on book navigation service.It focuses on user needs,design thought and implementation of main functions.According to the assessment of the application,the system can greatly enhance the efficiency and quality of library services.
Level crossings in complex two-dimensional potentials
Indian Academy of Sciences (India)
Qing-Hai Wang
2009-08-01
Two-dimensional $\\mathcal{PT}$-symmetric quantum-mechanical systems with the complex cubic potential 12 = 2 + 2 + 2 and the complex Hénon–Heiles potential HH = 2 + 2 + (2 − 3/3) are investigated. Using numerical and perturbative methods, energy spectra are obtained to high levels. Although both potentials respect the $\\mathcal{PT}$ symmetry, the complex energy eigenvalues appear when level crossing happens between same parity eigenstates.
Two-dimensional correlation spectroscopy in polymer study
Park, Yeonju; Noda, Isao; Jung, Young Mee
2015-01-01
This review outlines the recent works of two-dimensional correlation spectroscopy (2DCOS) in polymer study. 2DCOS is a powerful technique applicable to the in-depth analysis of various spectral data of polymers obtained under some type of perturbation. The powerful utility of 2DCOS combined with various analytical techniques in polymer studies and noteworthy developments of 2DCOS used in this field are also highlighted. PMID:25815286
Drift modes of a quasi-two-dimensional current sheet
Energy Technology Data Exchange (ETDEWEB)
Artemyev, A. V.; Malova, Kh. V.; Popov, V. Yu.; Zelenyi, L. M. [Russian Academy of Sciences, Space Research Institute (Russian Federation)
2012-03-15
Stability of a plasma configuration consisting of a thin one-dimensional current sheet embedded into a two-dimensional background current sheet is studied. Drift modes developing in plasma as unstable waves along the current direction are considered. Dispersion relations for kink and sausage perturbation modes are obtained depending on the ratio of parameters of thin and background current sheets. It is shown that the existence of the background sheet results in a decrease in the instability growth rates and a significant increase in the perturbation wavelengths. The role of drift modes in the excitation of oscillations observed in the current sheet of the Earth's magnetotail is discussed.
DEFF Research Database (Denmark)
2008-01-01
A Coding/Modulating units (200-1-200-N) outputs modulated symbols by modulating coding bit streams based on certain modulation scheme. The limited perturbation vector is calculated by using distribution of perturbation vectors. The original constellation points of modulated symbols are extended...
DEFF Research Database (Denmark)
2008-01-01
A Coding/Modulating units (200-1-200-N) outputs modulated symbols by modulating coding bit streams based on certain modulation scheme. The limited perturbation vector is calculated by using distribution of perturbation vectors. The original constellation points of modulated symbols are extended t...
Hadamard States and Two-dimensional Gravity
Salehi, H
2001-01-01
We have used a two-dimensional analog of the Hadamard state-condition to study the local constraints on the two-point function of a linear quantum field conformally coupled to a two-dimensional gravitational background. We develop a dynamical model in which the determination of the state of the quantum field is essentially related to the determination of a conformal frame. A particular conformal frame is then introduced in which a two-dimensional gravitational equation is established.
Topological defects in two-dimensional crystals
Chen, Yong; Qi, Wei-Kai
2008-01-01
By using topological current theory, we study the inner topological structure of the topological defects in two-dimensional (2D) crystal. We find that there are two elementary point defects topological current in two-dimensional crystal, one for dislocations and the other for disclinations. The topological quantization and evolution of topological defects in two-dimensional crystals are discussed. Finally, We compare our theory with Brownian-dynamics simulations in 2D Yukawa systems.
Spectral Radiative Properties of Two-Dimensional Rough Surfaces
Xuan, Yimin; Han, Yuge; Zhou, Yue
2012-12-01
Spectral radiative properties of two-dimensional rough surfaces are important for both academic research and practical applications. Besides material properties, surface structures have impact on the spectral radiative properties of rough surfaces. Based on the finite difference time domain algorithm, this paper studies the spectral energy propagation process on a two-dimensional rough surface and analyzes the effect of different factors such as the surface structure, angle, and polarization state of the incident wave on the spectral radiative properties of the two-dimensional rough surface. To quantitatively investigate the spatial distribution of energy reflected from the rough surface, the concept of the bidirectional reflectance distribution function is introduced. Correlation analysis between the reflectance and different impact factors is conducted to evaluate the influence degree. Comparison between the theoretical and experimental data is given to elucidate the accuracy of the computational code. This study is beneficial to optimizing the surface structures of optoelectronic devices such as solar cells.
Institute of Scientific and Technical Information of China (English)
于英政; 许宏丽
2014-01-01
With the wide application of two‐dimensional code, two‐dimensional code encryption technology has attracted more and more attention. QR(Quick Response) two‐dimensional code is a widely used two‐dimensional code. The different stages of the implementation procedure have different characteristics. This paper presents a multilevel fusion encryption algo‐rithm based on QR code, greatly improved the encryption intensity of QR code by using DES and fixed keys RC4 encryption in different stages. This algorithm does not significantly increase the length and the processing time of QR code. The experi‐mental data show the validity of the algorithm.%随着二维码的广泛应用，二维码加密技术受到越来越多的关注。快速响应（Quick Response ，QR）二维码是一种被广泛使用的二维码，其实现过程的不同阶段有不同的特点。论文提出一种基于QR二维码的多级融合加密算法概念，通过对不同阶段采取DES加密和固定密钥的RC4加密大大提高QR二维码的加密强度，同时不明显增加二维码的长度和处理时间。实验数据表明了论文所提算法的有效性。
Strongly interacting two-dimensional Dirac fermions
Lim, L.K.; Lazarides, A.; Hemmerich, Andreas; de Morais Smith, C.
2009-01-01
We show how strongly interacting two-dimensional Dirac fermions can be realized with ultracold atoms in a two-dimensional optical square lattice with an experimentally realistic, inherent gauge field, which breaks time reversal and inversion symmetries. We find remarkable phenomena in a temperature
Topology optimization of two-dimensional waveguides
DEFF Research Database (Denmark)
Jensen, Jakob Søndergaard; Sigmund, Ole
2003-01-01
In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss.......In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss....
Two-dimensional localized structures in harmonically forced oscillatory systems
Ma, Y.-P.; Knobloch, E.
2016-12-01
Two-dimensional spatially localized structures in the complex Ginzburg-Landau equation with 1:1 resonance are studied near the simultaneous presence of a steady front between two spatially homogeneous equilibria and a supercritical Turing bifurcation on one of them. The bifurcation structures of steady circular fronts and localized target patterns are computed in the Turing-stable and Turing-unstable regimes. In particular, localized target patterns grow along the solution branch via ring insertion at the core in a process reminiscent of defect-mediated snaking in one spatial dimension. Stability of axisymmetric solutions on these branches with respect to axisymmetric and nonaxisymmetric perturbations is determined, and parameter regimes with stable axisymmetric oscillons are identified. Direct numerical simulations reveal novel depinning dynamics of localized target patterns in the radial direction, and of circular and planar localized hexagonal patterns in the fully two-dimensional system.
Rahman, T.
2009-01-01
In this thesis, a finite element based perturbation approach is presented for geometrically nonlinear analysis of thin-walled structures. Geometrically nonlinear static and dynamic analyses are essential for this class of structures. Nowadays nonlinear analysis of thin-walled shell structures is oft
A Two-dimensional Magnetohydrodynamics Scheme for General Unstructured Grids
Livne, Eli; Dessart, Luc; Burrows, Adam; Meakin, Casey A.
2007-05-01
We report a new finite-difference scheme for two-dimensional magnetohydrodynamics (MHD) simulations, with and without rotation, in unstructured grids with quadrilateral cells. The new scheme is implemented within the code VULCAN/2D, which already includes radiation hydrodynamics in various approximations and can be used with arbitrarily moving meshes (ALEs). The MHD scheme, which consists of cell-centered magnetic field variables, preserves the nodal finite difference representation of divB by construction, and therefore any initially divergence-free field remains divergence-free through the simulation. In this paper, we describe the new scheme in detail and present comparisons of VULCAN/2D results with those of the code ZEUS/2D for several one-dimensional and two-dimensional test problems. The code now enables two-dimensional simulations of the collapse and explosion of the rotating, magnetic cores of massive stars. Moreover, it can be used to simulate the very wide variety of astrophysical problems for which multidimensional radiation magnetohydrodynamics (RMHD) is relevant.
Two Dimensional Plasmonic Cavities on Moire Surfaces
Balci, Sinan; Kocabas, Askin; Karabiyik, Mustafa; Kocabas, Coskun; Aydinli, Atilla
2010-03-01
We investigate surface plasmon polariton (SPP) cavitiy modes on two dimensional Moire surfaces in the visible spectrum. Two dimensional hexagonal Moire surface can be recorded on a photoresist layer using Interference lithography (IL). Two sequential exposures at slightly different angles in IL generate one dimensional Moire surfaces. Further sequential exposure for the same sample at slightly different angles after turning the sample 60 degrees around its own axis generates two dimensional hexagonal Moire cavity. Spectroscopic reflection measurements have shown plasmonic band gaps and cavity states at all the azimuthal angles (omnidirectional cavity and band gap formation) investigated. The plasmonic band gap edge and the cavity states energies show six fold symmetry on the two dimensional Moire surface as measured in reflection measurements.
Two-dimensional function photonic crystals
Liu, Xiao-Jing; Liang, Yu; Ma, Ji; Zhang, Si-Qi; Li, Hong; Wu, Xiang-Yao; Wu, Yi-Heng
2017-01-01
In this paper, we have studied two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , that can become true easily by electro-optical effect and optical kerr effect. We calculated the band gap structures of TE and TM waves, and found the TE (TM) wave band gaps of function photonic crystals are wider (narrower) than the conventional photonic crystals. For the two-dimensional function photonic crystals, when the dielectric constant functions change, the band gaps numbers, width and position should be changed, and the band gap structures of two-dimensional function photonic crystals can be adjusted flexibly, the needed band gap structures can be designed by the two-dimensional function photonic crystals, and it can be of help to design optical devices.
Two-Dimensional Planetary Surface Lander
Hemmati, H.; Sengupta, A.; Castillo, J.; McElrath, T.; Roberts, T.; Willis, P.
2014-06-01
A systems engineering study was conducted to leverage a new two-dimensional (2D) lander concept with a low per unit cost to enable scientific study at multiple locations with a single entry system as the delivery vehicle.
ARM11-based video capture system and two-dimensional code recognition%基于ARM11的视频采集系统及二维码识别
Institute of Scientific and Technical Information of China (English)
段东波; 靳天玉
2013-01-01
With the development of information technology,more and more application of ARM embedded system as the core. Therefore,further research ARM core and based on the ARM core application will make it better to meet the practical need. This article through to ARM core as well as the embedded Linux research, using QT programming,realized the video acquisition which based on Samsung S3C6410 processor and QR code recognition.The article emphasis on describes the process of Embedded Linux transplantation, Video acquisition and QR code recognition.%随着信息技术的发展，越来越多的领域应用ARM作为嵌入式系统的核心。因此，深入研究ARM核心以及基于ARM核心的应用使其更好的符合实际需要，便显得尤为重要。本文通过对ARM核心以及嵌入式Linux的研究，利用QT编程，实现了基于三星S3C6410处理器的视频采集以及二维码识别。文章重点描述了嵌入式Linux的移植、视频采集以及二维码识别等应用程序的流程。
Institute of Scientific and Technical Information of China (English)
李佳芮
2015-01-01
This thesis introduced the spreading characteristics of wechat and QR code's release,generate and threat,analyzed the problems in wechat network information communication from the case of phishing.Based on the concepts of complex network,we made a research on the characteristics and propagation model of complex network and introduced weighted network spread model,then applied them into the spread through wechat networks,trying to make a research on wechat dynamic broadcast about phishing hidden in QR code,and the analyzes were made quantitatively and qualitatively,which helped us have a better understanding on the spread of phising and find the key factor in spreading in order to propose an effective system to prevent the phishing spreading.%文章针对微信传播特点和二维码病毒的发布方式、如何生成以及危害进行简要概述,以隐藏在二维码中的钓鱼信息为例分析二维码在微信传播中存在的安全问题.通过对复杂网络的特征、传播模型的研究,结合加权网络传播模型的进一步分析,将这种研究结果应用到微信网络的传播中,对微信传播网络中的二维码钓鱼信息动态传播进行定性和定量研究,从而更加完备和深入地认识钓鱼信息传播过程,找到传播的关键因素,并简要设计了一套有效的系统来控制钓鱼信息的传播.
Complex Saddles in Two-dimensional Gauge Theory
Buividovich, P V; Valgushev, S N
2015-01-01
We study numerically the saddle point structure of two-dimensional (2D) lattice gauge theory, represented by the Gross-Witten-Wadia unitary matrix model. The saddle points are in general complex-valued, even though the original integration variables and action are real. We confirm the trans-series/instanton gas structure in the weak-coupling phase, and identify a new complex-saddle interpretation of non-perturbative effects in the strong-coupling phase. In both phases, eigenvalue tunneling refers to eigenvalues moving off the real interval, into the complex plane, and the weak-to-strong coupling phase transition is driven by saddle condensation.
Institute of Scientific and Technical Information of China (English)
梁飞凤; 刘海燕; 李彩婷; 张洁芳
2013-01-01
目的探讨应用二维条形码信息管理对手术灭菌器械进行质量追溯的效果。方法将16857件手术灭菌器械分为实验组8356件和对照组8501件，模拟实验组有276件和对照组有288件灭菌器械不合格，实验组使用二维条形码信息管理，对照组采用传统方法对手术灭菌不合格器械质量进行追溯。比较两组器械质量追溯花费时间的差异。结果实验组质量追溯时间短于对照组，两组比较，t=-244.09，t=P＜0.001，差异具有统计学意义。结论使用二维条形码信息管理对手术灭菌器械进行质量追溯，不仅能提高工作效率，同时保证手术病人的安全。%Objective To investigate the application of two dimensional bar code on the quality tracking of surgical instrument. Methods Sixty cases of surgical instrument packets without sterilization in sterilization and supply center were selected.The parkets were divided into the observation group and the control group with 30 cases in each group.The observation group was applied two dimensional bar code on the surgical instrument packets.We eraluated the effect of quality tracking according to the using time that started from discorering sterilization items unqualified to tracking to the patient who use this item.The control group was applied traditional methods.Results The quality tracking time of experiment group was significantly shorter than the time of control group. The difference was statistically significant(P<0.001).The staff satisfaction of the observation group was better than that of the control group.The difference was statistically significant(P<0.001).Conclusion Applying two dimensional bar code can improve the work efficiency,the sterilization quality of surgical instrument packet and guarantee the operation safety of patients.
Interpolation by two-dimensional cubic convolution
Shi, Jiazheng; Reichenbach, Stephen E.
2003-08-01
This paper presents results of image interpolation with an improved method for two-dimensional cubic convolution. Convolution with a piecewise cubic is one of the most popular methods for image reconstruction, but the traditional approach uses a separable two-dimensional convolution kernel that is based on a one-dimensional derivation. The traditional, separable method is sub-optimal for the usual case of non-separable images. The improved method in this paper implements the most general non-separable, two-dimensional, piecewise-cubic interpolator with constraints for symmetry, continuity, and smoothness. The improved method of two-dimensional cubic convolution has three parameters that can be tuned to yield maximal fidelity for specific scene ensembles characterized by autocorrelation or power-spectrum. This paper illustrates examples for several scene models (a circular disk of parametric size, a square pulse with parametric rotation, and a Markov random field with parametric spatial detail) and actual images -- presenting the optimal parameters and the resulting fidelity for each model. In these examples, improved two-dimensional cubic convolution is superior to several other popular small-kernel interpolation methods.
Large scale instabilities in two-dimensional magnetohydrodynamics
Boffetta; Celani; Prandi
2000-04-01
The stability of a sheared magnetic field is analyzed in two-dimensional magnetohydrodynamics with resistive and viscous dissipation. Using a multiple-scale analysis, it is shown that at large enough Reynolds numbers the basic state describing a motionless fluid and a layered magnetic field, becomes unstable with respect to large scale perturbations. The exact expressions for eddy-viscosity and eddy-resistivity are derived in the nearby of the critical point where the instability sets in. In this marginally unstable case the nonlinear phase of perturbation growth obeys to a Cahn-Hilliard-like dynamics characterized by coalescence of magnetic islands leading to a final new equilibrium state. High resolution numerical simulations confirm quantitatively the predictions of multiscale analysis.
TWO-DIMENSIONAL TOPOLOGY OF COSMOLOGICAL REIONIZATION
Energy Technology Data Exchange (ETDEWEB)
Wang, Yougang; Xu, Yidong; Chen, Xuelei [Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 China (China); Park, Changbom [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of); Kim, Juhan, E-mail: wangyg@bao.ac.cn, E-mail: cbp@kias.re.kr [Center for Advanced Computation, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of)
2015-11-20
We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two-dimensional genus curve for the early, middle, and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometre Array.
Two dimensional topology of cosmological reionization
Wang, Yougang; Xu, Yidong; Chen, Xuelei; Kim, Juhan
2015-01-01
We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two dimensional genus curve for the early, middle and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometer Array.
Two-dimensional x-ray diffraction
He, Bob B
2009-01-01
Written by one of the pioneers of 2D X-Ray Diffraction, this useful guide covers the fundamentals, experimental methods and applications of two-dimensional x-ray diffraction, including geometry convention, x-ray source and optics, two-dimensional detectors, diffraction data interpretation, and configurations for various applications, such as phase identification, texture, stress, microstructure analysis, crystallinity, thin film analysis and combinatorial screening. Experimental examples in materials research, pharmaceuticals, and forensics are also given. This presents a key resource to resea
Matching Two-dimensional Gel Electrophoresis' Spots
DEFF Research Database (Denmark)
Dos Anjos, António; AL-Tam, Faroq; Shahbazkia, Hamid Reza
2012-01-01
This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches. This ar......This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches...
Mobility anisotropy of two-dimensional semiconductors
Lang, Haifeng; Zhang, Shuqing; Liu, Zhirong
2016-12-01
The carrier mobility of anisotropic two-dimensional semiconductors under longitudinal acoustic phonon scattering was theoretically studied using deformation potential theory. Based on the Boltzmann equation with the relaxation time approximation, an analytic formula of intrinsic anisotropic mobility was derived, showing that the influence of effective mass on mobility anisotropy is larger than those of deformation potential constant or elastic modulus. Parameters were collected for various anisotropic two-dimensional materials (black phosphorus, Hittorf's phosphorus, BC2N , MXene, TiS3, and GeCH3) to calculate their mobility anisotropy. It was revealed that the anisotropic ratio is overestimated by the previously described method.
Towards two-dimensional search engines
Ermann, Leonardo; Chepelianskii, Alexei D.; Shepelyansky, Dima L.
2011-01-01
We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way the ranking of nodes becomes two-dimensional that paves the way for development of two-dimensional search engines of new type. Statistical properties of inf...
Piezoelectricity in Two-Dimensional Materials
Wu, Tao
2015-02-25
Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards embedding low-dimensional materials into future disruptive technologies. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.
Kronecker Product of Two-dimensional Arrays
Institute of Scientific and Technical Information of China (English)
Lei Hu
2006-01-01
Kronecker sequences constructed from short sequences are good sequences for spread spectrum communication systems. In this paper we study a similar problem for two-dimensional arrays, and we determine the linear complexity of the Kronecker product of two arrays. Our result shows that similar good property on linear complexity holds for Kronecker product of arrays.
Two-Dimensional Toda-Heisenberg Lattice
Directory of Open Access Journals (Sweden)
Vadim E. Vekslerchik
2013-06-01
Full Text Available We consider a nonlinear model that is a combination of the anisotropic two-dimensional classical Heisenberg and Toda-like lattices. In the framework of the Hirota direct approach, we present the field equations of this model as a bilinear system, which is closely related to the Ablowitz-Ladik hierarchy, and derive its N-soliton solutions.
A novel two dimensional particle velocity sensor
Pjetri, Olti; Wiegerink, Remco J.; Lammerink, Theo S.; Krijnen, Gijs J.
2013-01-01
In this paper we present a two wire, two-dimensional particle velocity sensor. The miniature sensor of size 1.0x2.5x0.525 mm, consisting of only two crossed wires, shows excellent directional sensitivity in both directions, thus requiring no directivity calibration, and is relatively easy to fabrica
Two-dimensional microstrip detector for neutrons
Energy Technology Data Exchange (ETDEWEB)
Oed, A. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)
1997-04-01
Because of their robust design, gas microstrip detectors, which were developed at ILL, can be assembled relatively quickly, provided the prefabricated components are available. At the beginning of 1996, orders were received for the construction of three two-dimensional neutron detectors. These detectors have been completed. The detectors are outlined below. (author). 2 refs.
Two-dimensional magma-repository interactions
Bokhove, O.
2001-01-01
Two-dimensional simulations of magma-repository interactions reveal that the three phases --a shock tube, shock reflection and amplification, and shock attenuation and decay phase-- in a one-dimensional flow tube model have a precursor. This newly identified phase ``zero'' consists of the impact of
Two-dimensional subwavelength plasmonic lattice solitons
Ye, F; Hu, B; Panoiu, N C
2010-01-01
We present a theoretical study of plasmonic lattice solitons (PLSs) formed in two-dimensional (2D) arrays of metallic nanowires embedded into a nonlinear medium with Kerr nonlinearity. We analyze two classes of 2D PLSs families, namely, fundamental and vortical PLSs in both focusing and defocusing media. Their existence, stability, and subwavelength spatial confinement are studied in detai
A two-dimensional Dirac fermion microscope
DEFF Research Database (Denmark)
Bøggild, Peter; Caridad, Jose; Stampfer, Christoph
2017-01-01
in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2...
Validation of lattice code 'EXCEL' with TIC experiments on uniform and regularly perturbed lattices
Energy Technology Data Exchange (ETDEWEB)
Ramakrishna, A., E-mail: anantatmula.ramakrishna@gmail.co [Atomic Energy Regulatory Board, Niyamak Bhavan, Anushaktinagar, Mumbai 400 094 (India); Jagannathan, V. [Light Water Reactors Physics Section, Reactor Physics Design Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Jain, R.P. [IIT Bombay, Mumbai (India)
2010-12-15
Temporary International Collective (TIC) was established in 1972 by an agreement among seven countries, namely, Bulgaria, Czechoslovakia, Germany, Hungary, Poland, Romania and Union of Soviet Socialist Republics. The main objective of TIC was to provide the experimental data for the reactor physics analysis of water cooled and water moderated power reactors (WWER). Extensive experimental work for different core configurations was carried out by TIC countries to investigate the physics behaviour of WWER lattices and the results were published in TIC volumes. Two VVER-1000 MWe reactors are currently in an advanced stage of construction and due for commissioning in Kudankulam, Tamil Nadu, India. Indigenous development of in-core fuel management computer codes for the analysis of hexagonal lattice cores is also in an advanced stage to address various design, operation and safety issues of VVER type cores. The validation of the above TIC lattice experiments will help in the identification of deficiencies in reactor physics design computational codes and the associated nuclear data libraries. In this paper, TIC experiments on uniform and regularly perturbed lattices have been analyzed as part of the validation of indigenous computer codes, EXCEL, TRIHEX-FA and HEXPIN developed at Light Water Reactors Physics Section, B.A.R.C. Neutron-nuclear multi-group cross-section libraries in WIMS/D format in 69/172 energy groups have been released by IAEA at the conclusion of WIMS library update project (WLUP). In the present study we have used libraries based on ENDF/B-6, ENDF/B-7, JEFF3.1 and JENDL3.2 evaluated nuclear datasets. The results of the theoretical analyses bring out the performance of the code system and various cross-section libraries.
Simple models of two-dimensional information sources and codes
DEFF Research Database (Denmark)
Justesen, Jørn; Shtarkov, Y. M.
1998-01-01
We consider discrete random fields which have simple descriptions of rows and columns. We present constructions which combine high entropy with simple means of generating the fields and analyzing the probability distribution. Hidden state Markov sources are an essential tool in the construction...
Development of a Two-Dimensional Implicit Interior Ballistics Code
1980-01-01
the universal gas constant, W is the gas molecular weight, u m and n is the covolume factor, which is composition dependent . Following Gough (Ref...c is dependent on the gas composition but not temperature. v The static enthalpy is then h = p e + p The specific heat at constant pressure is...Gun Interior Ballistics Transient Combustion Time- dependent Adaptive Grid 20, ABST’RACT (Cazrt&au:e _. .. ._._ lliO 11 ~ llltld ldenllly by block
Object-Oriented Two-Dimensional Electromagnetic Field Solver Code
2007-11-02
MX2 = sizeof (ds.svil 1); new TEdit (this, idcinfo0 1, MX 1); new TEdit (this, idcinfo02, MX 1); new TEdit (this, idcinfo03, MX1 ); new TEdit (this...idcinfo04, MX1 ); new TEdit (this, idcinfo05, MXl); new TEdit (this, idcinfo06, MXl); new TEdit (this, idcinfo07, MXl); new TEdit (this, idcinfol 1, MX2
Two-dimensional transport study of scrape off layer plasmas
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, Nobuyuki [Interdisciplinary Graduate School of Advanced Energy Engineering Sciences, Kyushu University, Fukuoka (Japan); Yagi, Masatoshi; Itoh, Sanae-I. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics
1999-09-01
Two-dimensional transport code is developed to analyzed the heat pulse propagation in the scrape-off layer plasma. The classical and anomalous transport models are considered as a thermal diffusivity perpendicular to the magnetic field. On the other hand, the classical transport model is chosen as a thermal diffusivity parallel to the magnetic field. The heat deposition profiles are evaluated for various kinds of transport models. It is found that the heat pulse which arrives at the divertor plate due to the classical transport is largest compared with other models. The steady state temperate profiles of the electron and ion are also discussed. (author)
Institute of Scientific and Technical Information of China (English)
顾伟; 况华; 孙科芬; 张科娜; 王天鹰
2013-01-01
目的：开发医院设备管理系统，提高设备资产管理工作的质量和效率。方法结合国家、行业、地方医疗器械编码标准，借助二维条码和移动技术开发一套符合医院设备管理需要的信息系统。结果本系统的使用，提升了医院整体管理水平。结论该系统实现了国有资产的规范管理、合理利用。%Objective To develop medical equipment management system to improve the quality and efficiency of equipment assets management. Methods Combined with national, industrial and local coding standards of medical equipment, the management system which is in accordance with management requirements of hospital equipment is developed by using two-dimensional bar code and mobile technologies. Results The overall management level of the hospital has been improved with the application of the management system. Conclusion The standard management and rational utilization of state-owned property have been implemented with the application of the system.
Electronics based on two-dimensional materials.
Fiori, Gianluca; Bonaccorso, Francesco; Iannaccone, Giuseppe; Palacios, Tomás; Neumaier, Daniel; Seabaugh, Alan; Banerjee, Sanjay K; Colombo, Luigi
2014-10-01
The compelling demand for higher performance and lower power consumption in electronic systems is the main driving force of the electronics industry's quest for devices and/or architectures based on new materials. Here, we provide a review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches. We focus on the performance limits and advantages of these materials and associated technologies, when exploited for both digital and analog applications, focusing on the main figures of merit needed to meet industry requirements. We also discuss the use of two-dimensional materials as an enabling factor for flexible electronics and provide our perspectives on future developments.
Two-dimensional ranking of Wikipedia articles
Zhirov, A. O.; Zhirov, O. V.; Shepelyansky, D. L.
2010-10-01
The Library of Babel, described by Jorge Luis Borges, stores an enormous amount of information. The Library exists ab aeterno. Wikipedia, a free online encyclopaedia, becomes a modern analogue of such a Library. Information retrieval and ranking of Wikipedia articles become the challenge of modern society. While PageRank highlights very well known nodes with many ingoing links, CheiRank highlights very communicative nodes with many outgoing links. In this way the ranking becomes two-dimensional. Using CheiRank and PageRank we analyze the properties of two-dimensional ranking of all Wikipedia English articles and show that it gives their reliable classification with rich and nontrivial features. Detailed studies are done for countries, universities, personalities, physicists, chess players, Dow-Jones companies and other categories.
Two-Dimensional NMR Lineshape Analysis
Waudby, Christopher A.; Ramos, Andres; Cabrita, Lisa D.; Christodoulou, John
2016-04-01
NMR titration experiments are a rich source of structural, mechanistic, thermodynamic and kinetic information on biomolecular interactions, which can be extracted through the quantitative analysis of resonance lineshapes. However, applications of such analyses are frequently limited by peak overlap inherent to complex biomolecular systems. Moreover, systematic errors may arise due to the analysis of two-dimensional data using theoretical frameworks developed for one-dimensional experiments. Here we introduce a more accurate and convenient method for the analysis of such data, based on the direct quantum mechanical simulation and fitting of entire two-dimensional experiments, which we implement in a new software tool, TITAN (TITration ANalysis). We expect the approach, which we demonstrate for a variety of protein-protein and protein-ligand interactions, to be particularly useful in providing information on multi-step or multi-component interactions.
Towards two-dimensional search engines
Ermann, Leonardo; Shepelyansky, Dima L
2011-01-01
We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way the ranking of nodes becomes two-dimensional that paves the way for development of two-dimensional search engines of new type. Information flow properties on PageRank-CheiRank plane are analyzed for networks of British, French and Italian Universities, Wikipedia, Linux Kernel, gene regulation and other networks. Methods of spam links control are also analyzed.
Toward two-dimensional search engines
Ermann, L.; Chepelianskii, A. D.; Shepelyansky, D. L.
2012-07-01
We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way, the ranking of nodes becomes two dimensional which paves the way for the development of two-dimensional search engines of a new type. Statistical properties of information flow on the PageRank-CheiRank plane are analyzed for networks of British, French and Italian universities, Wikipedia, Linux Kernel, gene regulation and other networks. A special emphasis is done for British universities networks using the large database publicly available in the UK. Methods of spam links control are also analyzed.
A two-dimensional Dirac fermion microscope
Bøggild, Peter; Caridad, José M.; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads
2017-06-01
The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.
A two-dimensional Dirac fermion microscope.
Bøggild, Peter; Caridad, José M; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads
2017-06-09
The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.
Two-Dimensional Scheduling: A Review
Directory of Open Access Journals (Sweden)
Zhuolei Xiao
2013-07-01
Full Text Available In this study, we present a literature review, classification schemes and analysis of methodology for scheduling problems on Batch Processing machine (BP with both processing time and job size constraints which is also regarded as Two-Dimensional (TD scheduling. Special attention is given to scheduling problems with non-identical job sizes and processing times, with details of the basic algorithms and other significant results.
Two dimensional fermions in four dimensional YM
Narayanan, R
2009-01-01
Dirac fermions in the fundamental representation of SU(N) live on a two dimensional torus flatly embedded in $R^4$. They interact with a four dimensional SU(N) Yang Mills vector potential preserving a global chiral symmetry at finite $N$. As the size of the torus in units of $\\frac{1}{\\Lambda_{SU(N)}}$ is varied from small to large, the chiral symmetry gets spontaneously broken in the infinite $N$ limit.
Two-dimensional Kagome photonic bandgap waveguide
DEFF Research Database (Denmark)
Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou;
2000-01-01
The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....
String breaking in two-dimensional QCD
Hornbostel, K J
1999-01-01
I present results of a numerical calculation of the effects of light quark-antiquark pairs on the linear heavy-quark potential in light-cone quantized two-dimensional QCD. I extract the potential from the Q-Qbar component of the ground-state wavefunction, and observe string breaking at the heavy-light meson pair threshold. I briefly comment on the states responsible for the breaking.
Two-dimensional supramolecular electron spin arrays.
Wäckerlin, Christian; Nowakowski, Jan; Liu, Shi-Xia; Jaggi, Michael; Siewert, Dorota; Girovsky, Jan; Shchyrba, Aneliia; Hählen, Tatjana; Kleibert, Armin; Oppeneer, Peter M; Nolting, Frithjof; Decurtins, Silvio; Jung, Thomas A; Ballav, Nirmalya
2013-05-07
A bottom-up approach is introduced to fabricate two-dimensional self-assembled layers of molecular spin-systems containing Mn and Fe ions arranged in a chessboard lattice. We demonstrate that the Mn and Fe spin states can be reversibly operated by their selective response to coordination/decoordination of volatile ligands like ammonia (NH3). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Two dimensional echocardiographic detection of intraatrial masses.
DePace, N L; Soulen, R L; Kotler, M N; Mintz, G S
1981-11-01
With two dimensional echocardiography, a left atrial mass was detected in 19 patients. Of these, 10 patients with rheumatic mitral stenosis had a left atrial thrombus. The distinctive two dimensional echocardiographic features of left atrial thrombus included a mass of irregular nonmobile laminated echos within an enlarged atrial cavity, usually with a broad base of attachment to the posterior left atrial wall. Seven patients had a left atrial myxoma. Usually, the myxoma appeared as a mottled ovoid, sharply demarcated mobile mass attached to the interatrial septum. One patient had a right atrial angiosarcoma that appeared as a nonmobile mass extending from the inferior vena caval-right atrial junction into the right atrial cavity. One patient had a left atrial leiomyosarcoma producing a highly mobile mass attached to the lateral wall of the left atrium. M mode echocardiography detected six of the seven myxomas, one thrombus and neither of the other tumors. Thus, two dimensional echocardiography appears to be the technique of choice in the detection, localization and differentiation of intraatrial masses.
Commensurability oscillations in a two-dimensional lateral superlattice
Davies, John; Long, Andrew; Grant, David; Chowdhury, Suja
2000-03-01
We have calculated and measured conduction in a two-dimensional electron gas subject to a weak two-dimensional periodic potential and a normal magnetic field. Simulations with a potential Vx \\cos(2π x/a) + Vy \\cos(2π y/a) show the usual commensurability oscillations in ρ_xx(B) with Vx alone. The introduction of Vy suppresses these oscillations, rather than introducing the additional oscillations in ρ_yy(B) expected from previous perturbation theories. We explain this in terms of drift of the guiding center of cyclotron motion along contours of an effective potential: open orbits of the guiding center contribute to conduction but closed orbits do not. All orbits are closed in a symmetric superlattice with |V_x| = |V_y| and commensurability oscillations are therefore quenched. Experiments on etched superlattices confirm this picture. Conventional lattice-matched samples give a symmetric potential and weak oscillations; the symmetry is broken by the piezoelectric effect in stressed samples, leading to strong oscillations. Periodic modulation of the magnetic field can be treated in the same way, which explains previous experimental results.
Nematic Equilibria on a Two-Dimensional Annulus
Lewis, A. H.
2017-01-16
We study planar nematic equilibria on a two-dimensional annulus with strong and weak tangent anchoring, in the Oseen–Frank theoretical framework. We analyze a radially invariant defect-free state and compute analytic stability criteria for this state in terms of the elastic anisotropy, annular aspect ratio, and anchoring strength. In the strong anchoring case, we define and characterize a new spiral-like equilibrium which emerges as the defect-free state loses stability. In the weak anchoring case, we compute stability diagrams that quantify the response of the defect-free state to radial and azimuthal perturbations. We study sector equilibria on sectors of an annulus, including the effects of weak anchoring and elastic anisotropy, giving novel insights into the correlation between preferred numbers of boundary defects and the geometry. We numerically demonstrate that these sector configurations can approximate experimentally observed equilibria with boundary defects.
Anomaly matching condition in two-dimensional systems
Dubinkin, O; Gubankova, E
2016-01-01
Based on Son-Yamamoto relation obtained for transverse part of triangle axial anomaly in ${\\rm QCD}_4$, we derive its analog in two-dimensional system. It connects the transverse part of mixed vector-axial current two-point function with diagonal vector and axial current two-point functions. Being fully non-perturbative, this relation may be regarded as anomaly matching for conductivities or certain transport coefficients depending on the system. We consider the holographic RG flows in holographic Yang-Mills-Chern-Simons theory via the Hamilton-Jacobi equation with respect to the radial coordinate. Within this holographic model it is found that the RG flows for the following relations are diagonal: Son-Yamamoto relation and the left-right polarization operator. Thus the Son-Yamamoto relation holds at wide range of energy scales.
Collective Modes in Two Dimensional Binary Yukawa Systems
Kalman, Gabor J; Donko, Zoltan; Golden, Kenneth I; Kyrkos, Stamatios
2013-01-01
We analyze via theoretical approaches and molecular dynamics simulations the collective mode structure of strongly coupled two-dimensional binary Yukawa systems, for selected density, mass and charge ratios, both in the liquid and crystalline solid phases. Theoretically, the liquid phase is described through the Quasi-Localized Charge Approximation (QLCA) approach, while in the crystalline phase we study the centered honeycomb and the staggered rectangular crystal structures through the standard harmonic phonon approximation. We identify "longitudinal" and "transverse" acoustic and optic modes and find that the longitudinal acoustic mode evolves from its weakly coupled counterpart in a discontinuous non-perturbative fashion. The low frequency acoustic excitations are governed by the oscillation frequency of the average atom, while the high frequency optic excitation frequencies are related to the Einstein frequencies of the systems.
Stability of a Two-Dimensional Poiseuille-Type Flow for a Viscoelastic Fluid
Endo, Masakazu; Giga, Yoshikazu; Götz, Dario; Liu, Chun
2017-03-01
A viscoelastic flow in a two-dimensional layer domain is considered. An L 2-stability of the Poiseuille-type flow is established provided that both Poiseuille flow and perturbation is sufficiently small. Our analysis is based on a stream function formulation introduced by Lin et al. (Commun Pure Appl Math 58(11):1437-1471, 2005).
Weakly disordered two-dimensional Frenkel excitons
Boukahil, A.; Zettili, Nouredine
2004-03-01
We report the results of studies of the optical properties of weakly disordered two- dimensional Frenkel excitons in the Coherent Potential Approximation (CPA). An approximate complex Green's function for a square lattice with nearest neighbor interactions is used in the self-consistent equation to determine the coherent potential. It is shown that the Density of States is very much affected by the logarithmic singularities in the Green's function. Our CPA results are in excellent agreement with previous investigations by Schreiber and Toyozawa using the Monte Carlo simulation.
Two-dimensional photonic crystal surfactant detection.
Zhang, Jian-Tao; Smith, Natasha; Asher, Sanford A
2012-08-07
We developed a novel two-dimensional (2-D) crystalline colloidal array photonic crystal sensing material for the visual detection of amphiphilic molecules in water. A close-packed polystyrene 2-D array monolayer was embedded in a poly(N-isopropylacrylamide) (PNIPAAm)-based hydrogel film. These 2-D photonic crystals placed on a mirror show intense diffraction that enables them to be used for visual determination of analytes. Binding of surfactant molecules attaches ions to the sensor that swells the PNIPAAm-based hydrogel. The resulting increase in particle spacing red shifts the 2-D diffracted light. Incorporation of more hydrophobic monomers increases the sensitivity to surfactants.
Theory of two-dimensional transformations
Kanayama, Yutaka J.; Krahn, Gary W.
1998-01-01
The article of record may be found at http://dx.doi.org/10.1109/70.720359 Robotics and Automation, IEEE Transactions on This paper proposes a new "heterogeneous" two-dimensional (2D) transformation group ___ to solve motion analysis/planning problems in robotics. In this theory, we use a 3×1 matrix to represent a transformation as opposed to a 3×3 matrix in the homogeneous formulation. First, this theory is as capable as the homogeneous theory, Because of the minimal size, its implement...
Two-dimensional ranking of Wikipedia articles
Zhirov, A O; Shepelyansky, D L
2010-01-01
The Library of Babel, described by Jorge Luis Borges, stores an enormous amount of information. The Library exists {\\it ab aeterno}. Wikipedia, a free online encyclopaedia, becomes a modern analogue of such a Library. Information retrieval and ranking of Wikipedia articles become the challenge of modern society. We analyze the properties of two-dimensional ranking of all Wikipedia English articles and show that it gives their reliable classification with rich and nontrivial features. Detailed studies are done for countries, universities, personalities, physicists, chess players, Dow-Jones companies and other categories.
Mobility anisotropy of two-dimensional semiconductors
Lang, Haifeng; Liu, Zhirong
2016-01-01
The carrier mobility of anisotropic two-dimensional (2D) semiconductors under longitudinal acoustic (LA) phonon scattering was theoretically studied with the deformation potential theory. Based on Boltzmann equation with relaxation time approximation, an analytic formula of intrinsic anisotropic mobility was deduced, which shows that the influence of effective mass to the mobility anisotropy is larger than that of deformation potential constant and elastic modulus. Parameters were collected for various anisotropic 2D materials (black phosphorus, Hittorf's phosphorus, BC$_2$N, MXene, TiS$_3$, GeCH$_3$) to calculate their mobility anisotropy. It was revealed that the anisotropic ratio was overestimated in the past.
Sums of two-dimensional spectral triples
DEFF Research Database (Denmark)
Christensen, Erik; Ivan, Cristina
2007-01-01
construct a sum of two dimensional modules which reflects some aspects of the topological dimensions of the compact metric space, but this will only give the metric back approximately. At the end we make an explicit computation of the last module for the unit interval in. The metric is recovered exactly......, the Dixmier trace induces a multiple of the Lebesgue integral but the growth of the number of eigenvalues is different from the one found for the standard differential operator on the unit interval....
Binding energy of two-dimensional biexcitons
DEFF Research Database (Denmark)
Singh, Jai; Birkedal, Dan; Vadim, Lyssenko;
1996-01-01
Using a model structure for a two-dimensional (2D) biexciton confined in a quantum well, it is shown that the form of the Hamiltonian of the 2D biexciton reduces into that of an exciton. The binding energies and Bohr radii of a 2D biexciton in its various internal energy states are derived...... analytically using the fractional dimension approach. The ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be 0.228, which agrees very well with the recent experimental value. The results of our approach are compared with those of earlier theories....
Dynamics of film. [two dimensional continua theory
Zak, M.
1979-01-01
The general theory of films as two-dimensional continua are elaborated upon. As physical realizations of such a model this paper examines: inextensible films, elastic films, and nets. The suggested dynamic equations have enabled us to find out the characteristic speeds of wave propagation of the invariants of external and internal geometry and formulate the criteria of instability of their shape. Also included herein is a detailed account of the equation describing the film motions beyond the limits of the shape stability accompanied by the formation of wrinkles. The theory is illustrated by examples.
Two-dimensional gauge theoretic supergravities
Cangemi, D.; Leblanc, M.
1994-05-01
We investigate two-dimensional supergravity theories, which can be built from a topological and gauge invariant action defined on an ordinary surface. One is the N = 1 supersymmetric extension of the Jackiw-Teitelboim model presented by Chamseddine in a superspace formalism. We complement the proof of Montano, Aoaki and Sonnenschein that this extension is topological and gauge invariant, based on the graded de Sitter algebra. Not only do the equations of motion correspond to the supergravity ones and do gauge transformations encompass local supersymmetries, but we also identify the ∫-theory with the superfield formalism action written by Chamseddine. Next, we show that the N = 1 supersymmetric extension of string-inspired two-dimensional dilaton gravity put forward by Park and Strominger cannot be written as a ∫-theory. As an alternative, we propose two topological and gauge theories that are based on a graded extension of the extended Poincaré algebra and satisfy a vanishing-curvature condition. Both models are supersymmetric extensions of the string-inspired dilaton gravity.
Two-Dimensional Theory of Scientific Representation
Directory of Open Access Journals (Sweden)
A Yaghmaie
2013-03-01
Full Text Available Scientific representation is an interesting topic for philosophers of science, many of whom have recently explored it from different points of view. There are currently two competing approaches to the issue: cognitive and non-cognitive, and each of them claims its own merits over the other. This article tries to provide a hybrid theory of scientific representation, called Two-Dimensional Theory of Scientific Representation, which has the merits of the two accounts and is free of their shortcomings. To do this, we will argue that although scientific representation needs to use the notion of intentionality, such a notion is defined and realized in a simply structural form contrary to what cognitive approach says about intentionality. After a short introduction, the second part of the paper is devoted to introducing theories of scientific representation briefly. In the third part, the structural accounts of representation will be criticized. The next step is to introduce the two-dimensional theory which involves two key components: fixing and structural fitness. It will be argued that fitness is an objective and non-intentional relation, while fixing is intentional.
Two-dimensional shape memory graphene oxide
Chang, Zhenyue; Deng, Junkai; Chandrakumara, Ganaka G.; Yan, Wenyi; Liu, Jefferson Zhe
2016-06-01
Driven by the increasing demand for micro-/nano-technologies, stimuli-responsive shape memory materials at nanoscale have recently attracted great research interests. However, by reducing the size of conventional shape memory materials down to approximately nanometre range, the shape memory effect diminishes. Here, using density functional theory calculations, we report the discovery of a shape memory effect in a two-dimensional atomically thin graphene oxide crystal with ordered epoxy groups, namely C8O. A maximum recoverable strain of 14.5% is achieved as a result of reversible phase transition between two intrinsically stable phases. Our calculations conclude co-existence of the two stable phases in a coherent crystal lattice, giving rise to the possibility of constructing multiple temporary shapes in a single material, thus, enabling highly desirable programmability. With an atomic thickness, excellent shape memory mechanical properties and electric field stimulus, the discovery of a two-dimensional shape memory graphene oxide opens a path for the development of exceptional micro-/nano-electromechanical devices.
Institute of Scientific and Technical Information of China (English)
XU Quan; TIAN Qiang
2007-01-01
Two-dimensional compact-like discrete breathers in discrete two-dimensional monatomic square lattices are investigated by discussing a generafized discrete two-dimensional monatomic model.It is proven that the twodimensional compact-like discrete breathers exist not only in two-dimensional soft Ф4 potentials but also in hard two-dimensional Ф4 potentials and pure two-dimensional K4 lattices.The measurements of the two-dimensional compact-like discrete breather cores in soft and hard two-dimensional Ф4 potential are determined by coupling parameter K4,while those in pure two-dimensional K4 lattices have no coupling with parameter K4.The stabilities of the two-dimensional compact-like discrete breathers correlate closely to the coupling parameter K4 and the boundary condition of lattices.
Fast Ion Effects on Fishbones and n=1 Kinks in JET Simulated by a Non-perturbative NOVA-KN Code
Energy Technology Data Exchange (ETDEWEB)
N.N. Gorelenkov; C.Z. Cheng; V.G. Kiptily; M.J. Mantsinen; S.E. Sharapov; the JET-EFDA Contributors
2004-10-28
New global non-perturbative hybrid code, NOVA-KN, and simulations of resonant type modes in JET [Joint European Torus] plasmas driven by energetic H-minority ions are presented. The NOVA-KN code employs the ideal-MHD description for the background plasma and treats non-perturbatively the fast particle kinetic response, which includes the fast ion finite orbit width (FOW) effect. In particular, the n = 1 fishbone mode, which is in precession drift resonance with fast ions, is studied. The NOVA-KN code is applied to model an n = 1 (f = 50-80kHz) MHD activity observed recently in JET low density plasma discharges with high fast ion (H-minority) energy content generated during the ion cyclotron resonance heating (ICRH). This n = 1 MHD activity is interpreted as the instability of the n = 1 precession drift frequency fishbone modes.
Fault-tolerance in Two-dimensional Topological Systems
Anderson, Jonas T.
This thesis is a collection of ideas with the general goal of building, at least in the abstract, a local fault-tolerant quantum computer. The connection between quantum information and topology has proven to be an active area of research in several fields. The introduction of the toric code by Alexei Kitaev demonstrated the usefulness of topology for quantum memory and quantum computation. Many quantum codes used for quantum memory are modeled by spin systems on a lattice, with operators that extract syndrome information placed on vertices or faces of the lattice. It is natural to wonder whether the useful codes in such systems can be classified. This thesis presents work that leverages ideas from topology and graph theory to explore the space of such codes. Homological stabilizer codes are introduced and it is shown that, under a set of reasonable assumptions, any qubit homological stabilizer code is equivalent to either a toric code or a color code. Additionally, the toric code and the color code correspond to distinct classes of graphs. Many systems have been proposed as candidate quantum computers. It is very desirable to design quantum computing architectures with two-dimensional layouts and low complexity in parity-checking circuitry. Kitaev's surface codes provided the first example of codes satisfying this property. They provided a new route to fault tolerance with more modest overheads and thresholds approaching 1%. The recently discovered color codes share many properties with the surface codes, such as the ability to perform syndrome extraction locally in two dimensions. Some families of color codes admit a transversal implementation of the entire Clifford group. This work investigates color codes on the 4.8.8 lattice known as triangular codes. I develop a fault-tolerant error-correction strategy for these codes in which repeated syndrome measurements on this lattice generate a three-dimensional space-time combinatorial structure. I then develop an
On the existence of two-dimensional nonlinear steady states in plane Couette flow
Rincon, Francois
2007-01-01
The problem of two-dimensional steady nonlinear dynamics in plane Couette flow is revisited using homotopy from either plane Poiseuille flow or from plane Couette flow perturbed by a small symmetry-preserving identity operator. Our results show that it is not possible to obtain the nonlinear plane Couette flow solutions reported by Cherhabili and Ehrenstein [Eur. J. Mech. B/Fluids, 14, 667 (1995)] using their Poiseuille-Couette homotopy. We also demonstrate that the steady solutions obtained by Mehta and Healey [Phys. Fluids, 17, 4108 (2005)] for small symmetry-preserving perturbations are influenced by an artefact of the modified system of equations used in their paper. However, using a modified version of their model does not help to find plane Couette flow solution in the limit of vanishing symmetry-preserving perturbations either. The issue of the existence of two-dimensional nonlinear steady states in plane Couette flow remains unsettled.
Probabilistic Universality in two-dimensional Dynamics
Lyubich, Mikhail
2011-01-01
In this paper we continue to explore infinitely renormalizable H\\'enon maps with small Jacobian. It was shown in [CLM] that contrary to the one-dimensional intuition, the Cantor attractor of such a map is non-rigid and the conjugacy with the one-dimensional Cantor attractor is at most 1/2-H\\"older. Another formulation of this phenomenon is that the scaling structure of the H\\'enon Cantor attractor differs from its one-dimensional counterpart. However, in this paper we prove that the weight assigned by the canonical invariant measure to these bad spots tends to zero on microscopic scales. This phenomenon is called {\\it Probabilistic Universality}. It implies, in particular, that the Hausdorff dimension of the canonical measure is universal. In this way, universality and rigidity phenomena of one-dimensional dynamics assume a probabilistic nature in the two-dimensional world.
Two-dimensional position sensitive neutron detector
Indian Academy of Sciences (India)
A M Shaikh; S S Desai; A K Patra
2004-08-01
A two-dimensional position sensitive neutron detector has been developed. The detector is a 3He + Kr filled multiwire proportional counter with charge division position readout and has a sensitive area of 345 mm × 345 mm, pixel size 5 mm × 5 mm, active depth 25 mm and is designed for efficiency of 70% for 4 Å neutrons. The detector is tested with 0.5 bar 3He + 1.5 bar krypton gas mixture in active chamber and 2 bar 4He in compensating chamber. The pulse height spectrum recorded at an anode potential of 2000 V shows energy resolution of ∼ 25% for the 764 keV peak. A spatial resolution of 8 mm × 6 mm is achieved. The detector is suitable for SANS studies in the range of 0.02–0.25 Å-1.
Two-dimensional heterostructures for energy storage
Pomerantseva, Ekaterina; Gogotsi, Yury
2017-07-01
Two-dimensional (2D) materials provide slit-shaped ion diffusion channels that enable fast movement of lithium and other ions. However, electronic conductivity, the number of intercalation sites, and stability during extended cycling are also crucial for building high-performance energy storage devices. While individual 2D materials, such as graphene, show some of the required properties, none of them can offer all properties needed to maximize energy density, power density, and cycle life. Here we argue that stacking different 2D materials into heterostructured architectures opens an opportunity to construct electrodes that would combine the advantages of the individual building blocks while eliminating the associated shortcomings. We discuss characteristics of common 2D materials and provide examples of 2D heterostructured electrodes that showed new phenomena leading to superior electrochemical performance. We also consider electrode fabrication approaches and finally outline future steps to create 2D heterostructured electrodes that could greatly expand current energy storage technologies.
Rationally synthesized two-dimensional polymers.
Colson, John W; Dichtel, William R
2013-06-01
Synthetic polymers exhibit diverse and useful properties and influence most aspects of modern life. Many polymerization methods provide linear or branched macromolecules, frequently with outstanding functional-group tolerance and molecular weight control. In contrast, extending polymerization strategies to two-dimensional periodic structures is in its infancy, and successful examples have emerged only recently through molecular framework, surface science and crystal engineering approaches. In this Review, we describe successful 2D polymerization strategies, as well as seminal research that inspired their development. These methods include the synthesis of 2D covalent organic frameworks as layered crystals and thin films, surface-mediated polymerization of polyfunctional monomers, and solid-state topochemical polymerizations. Early application targets of 2D polymers include gas separation and storage, optoelectronic devices and membranes, each of which might benefit from predictable long-range molecular organization inherent to this macromolecular architecture.
Janus Spectra in Two-Dimensional Flows
Liu, Chien-Chia; Cerbus, Rory T.; Chakraborty, Pinaki
2016-09-01
In large-scale atmospheric flows, soap-film flows, and other two-dimensional flows, the exponent of the turbulent energy spectra, α , may theoretically take either of two distinct values, 3 or 5 /3 , but measurements downstream of obstacles have invariably revealed α =3 . Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which α transitions from 3 to 5 /3 for the streamwise fluctuations but remains equal to 3 for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows.
Local doping of two-dimensional materials
Wong, Dillon; Velasco, Jr, Jairo; Ju, Long; Kahn, Salman; Lee, Juwon; Germany, Chad E.; Zettl, Alexander K.; Wang, Feng; Crommie, Michael F.
2016-09-20
This disclosure provides systems, methods, and apparatus related to locally doping two-dimensional (2D) materials. In one aspect, an assembly including a substrate, a first insulator disposed on the substrate, a second insulator disposed on the first insulator, and a 2D material disposed on the second insulator is formed. A first voltage is applied between the 2D material and the substrate. With the first voltage applied between the 2D material and the substrate, a second voltage is applied between the 2D material and a probe positioned proximate the 2D material. The second voltage between the 2D material and the probe is removed. The first voltage between the 2D material and the substrate is removed. A portion of the 2D material proximate the probe when the second voltage was applied has a different electron density compared to a remainder of the 2D material.
Two-dimensional fourier transform spectrometer
Energy Technology Data Exchange (ETDEWEB)
DeFlores, Lauren; Tokmakoff, Andrei
2016-10-25
The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.
Two-dimensional fourier transform spectrometer
DeFlores, Lauren; Tokmakoff, Andrei
2013-09-03
The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.
FACE RECOGNITION USING TWO DIMENSIONAL LAPLACIAN EIGENMAP
Institute of Scientific and Technical Information of China (English)
Chen Jiangfeng; Yuan Baozong; Pei Bingnan
2008-01-01
Recently,some research efforts have shown that face images possibly reside on a nonlinear sub-manifold. Though Laplacianfaces method considered the manifold structures of the face images,it has limits to solve face recognition problem. This paper proposes a new feature extraction method,Two Dimensional Laplacian EigenMap (2DLEM),which especially considers the manifold structures of the face images,and extracts the proper features from face image matrix directly by using a linear transformation. As opposed to Laplacianfaces,2DLEM extracts features directly from 2D images without a vectorization preprocessing. To test 2DLEM and evaluate its performance,a series of ex-periments are performed on the ORL database and the Yale database. Moreover,several experiments are performed to compare the performance of three 2D methods. The experiments show that 2DLEM achieves the best performance.
Equivalency of two-dimensional algebras
Energy Technology Data Exchange (ETDEWEB)
Santos, Gildemar Carneiro dos; Pomponet Filho, Balbino Jose S. [Universidade Federal da Bahia (UFBA), BA (Brazil). Inst. de Fisica
2011-07-01
Full text: Let us consider a vector z = xi + yj over the field of real numbers, whose basis (i,j) satisfy a given algebra. Any property of this algebra will be reflected in any function of z, so we can state that the knowledge of the properties of an algebra leads to more general conclusions than the knowledge of the properties of a function. However structural properties of an algebra do not change when this algebra suffers a linear transformation, though the structural constants defining this algebra do change. We say that two algebras are equivalent to each other whenever they are related by a linear transformation. In this case, we have found that some relations between the structural constants are sufficient to recognize whether or not an algebra is equivalent to another. In spite that the basis transform linearly, the structural constants change like a third order tensor, but some combinations of these tensors result in a linear transformation, allowing to write the entries of the transformation matrix as function of the structural constants. Eventually, a systematic way to find the transformation matrix between these equivalent algebras is obtained. In this sense, we have performed the thorough classification of associative commutative two-dimensional algebras, and find that even non-division algebra may be helpful in solving non-linear dynamic systems. The Mandelbrot set was used to have a pictorial view of each algebra, since equivalent algebras result in the same pattern. Presently we have succeeded in classifying some non-associative two-dimensional algebras, a task more difficult than for associative one. (author)
Energy Technology Data Exchange (ETDEWEB)
Boudesocque-Dubois, C.; Clarisse, J.M
2007-07-01
In the context of linear perturbation computations of planar or spherically symmetric flows, we propose numerical methods, in Lagrangian coordinates, for integrating the one-dimensional gas dynamics equations with nonlinear heat conduction and their linear perturbations. Numerical results are presented for different configurations, with or without flow motion. (authors)
Grant, David E.; Long, Andrew R.; Davies, John H.
2000-05-01
We have simulated conduction in a two-dimensional electron gas subject to a weak two-dimensional periodic potential Vx cos(2πx/a)+Vy cos(2πy/a). The usual commensurability oscillations in ρxx(B) are seen with Vx alone. An increase of Vy suppresses these oscillations, rather than introducing the additional oscillations in ρyy(B) expected from previous perturbation theories. We show that this behavior arises from drift of the guiding center of cyclotron motion along contours of an effective potential. Periodic modulation in the magnetic field can be treated in the same way.
Surface Ship Shock Modeling and Simulation: Two-Dimensional Analysis
Directory of Open Access Journals (Sweden)
Young S. Shin
1998-01-01
Full Text Available The modeling and simulation of the response of a surface ship system to underwater explosion requires an understanding of many different subject areas. These include the process of underwater explosion events, shock wave propagation, explosion gas bubble behavior and bubble-pulse loading, bulk and local cavitation, free surface effect, fluid-structure interaction, and structural dynamics. This paper investigates the effects of fluid-structure interaction and cavitation on the response of a surface ship using USA-NASTRAN-CFA code. First, the one-dimensional Bleich-Sandler model is used to validate the approach, and second, the underwater shock response of a two-dimensional mid-section model of a surface ship is predicted with a surrounding fluid model using a constitutive equation of a bilinear fluid which does not allow transmission of negative pressures.
On numerical evaluation of two-dimensional phase integrals
DEFF Research Database (Denmark)
Lessow, H.; Rusch, W.; Schjær-Jacobsen, Hans
1975-01-01
The relative advantages of several common numerical integration algorithms used in computing two-dimensional phase integrals are evaluated.......The relative advantages of several common numerical integration algorithms used in computing two-dimensional phase integrals are evaluated....
Perspective: Two-dimensional resonance Raman spectroscopy
Molesky, Brian P.; Guo, Zhenkun; Cheshire, Thomas P.; Moran, Andrew M.
2016-11-01
Two-dimensional resonance Raman (2DRR) spectroscopy has been developed for studies of photochemical reaction mechanisms and structural heterogeneity in complex systems. The 2DRR method can leverage electronic resonance enhancement to selectively probe chromophores embedded in complex environments (e.g., a cofactor in a protein). In addition, correlations between the two dimensions of the 2DRR spectrum reveal information that is not available in traditional Raman techniques. For example, distributions of reactant and product geometries can be correlated in systems that undergo chemical reactions on the femtosecond time scale. Structural heterogeneity in an ensemble may also be reflected in the 2D spectroscopic line shapes of both reactive and non-reactive systems. In this perspective article, these capabilities of 2DRR spectroscopy are discussed in the context of recent applications to the photodissociation reactions of triiodide and myoglobin. We also address key differences between the signal generation mechanisms for 2DRR and off-resonant 2D Raman spectroscopies. Most notably, it has been shown that these two techniques are subject to a tradeoff between sensitivity to anharmonicity and susceptibility to artifacts. Overall, recent experimental developments and applications of the 2DRR method suggest great potential for the future of the technique.
Janus spectra in two-dimensional flows
Liu, Chien-Chia; Chakraborty, Pinaki
2016-01-01
In theory, large-scale atmospheric flows, soap-film flows and other two-dimensional flows may host two distinct types of turbulent energy spectra---in one, $\\alpha$, the spectral exponent of velocity fluctuations, equals $3$ and the fluctuations are dissipated at the small scales, and in the other, $\\alpha=5/3$ and the fluctuations are dissipated at the large scales---but measurements downstream of obstacles have invariably revealed $\\alpha = 3$. Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which $\\alpha$ has transitioned from $3$ to $5/3$ for the streamwise fluctuations but remains equal to $3$ for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows...
Comparative Two-Dimensional Fluorescence Gel Electrophoresis.
Ackermann, Doreen; König, Simone
2018-01-01
Two-dimensional comparative fluorescence gel electrophoresis (CoFGE) uses an internal standard to increase the reproducibility of coordinate assignment for protein spots visualized on 2D polyacrylamide gels. This is particularly important for samples, which need to be compared without the availability of replicates and thus cannot be studied using differential gel electrophoresis (DIGE). CoFGE corrects for gel-to-gel variability by co-running with the sample proteome a standardized marker grid of 80-100 nodes, which is formed by a set of purified proteins. Differentiation of reference and analyte is possible by the use of two fluorescent dyes. Variations in the y-dimension (molecular weight) are corrected by the marker grid. For the optional control of the x-dimension (pI), azo dyes can be used. Experiments are possible in both vertical and horizontal (h) electrophoresis devices, but hCoFGE is much easier to perform. For data analysis, commercial software capable of warping can be adapted.
Two-dimensional hexagonal semiconductors beyond graphene
Nguyen, Bich Ha; Hieu Nguyen, Van
2016-12-01
The rapid and successful development of the research on graphene and graphene-based nanostructures has been substantially enlarged to include many other two-dimensional hexagonal semiconductors (THS): phosphorene, silicene, germanene, hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMDCs) such as MoS2, MoSe2, WS2, WSe2 as well as the van der Waals heterostructures of various THSs (including graphene). The present article is a review of recent works on THSs beyond graphene and van der Waals heterostructures composed of different pairs of all THSs. One among the priorities of new THSs compared to graphene is the presence of a non-vanishing energy bandgap which opened up the ability to fabricate a large number of electronic, optoelectronic and photonic devices on the basis of these new materials and their van der Waals heterostructures. Moreover, a significant progress in the research on TMDCs was the discovery of valley degree of freedom. The results of research on valley degree of freedom and the development of a new technology based on valley degree of freedom-valleytronics are also presented. Thus the scientific contents of the basic research and practical applications os THSs are very rich and extremely promising.
Two-Dimensional Phononic Crystals: Disorder Matters.
Wagner, Markus R; Graczykowski, Bartlomiej; Reparaz, Juan Sebastian; El Sachat, Alexandros; Sledzinska, Marianna; Alzina, Francesc; Sotomayor Torres, Clivia M
2016-09-14
The design and fabrication of phononic crystals (PnCs) hold the key to control the propagation of heat and sound at the nanoscale. However, there is a lack of experimental studies addressing the impact of order/disorder on the phononic properties of PnCs. Here, we present a comparative investigation of the influence of disorder on the hypersonic and thermal properties of two-dimensional PnCs. PnCs of ordered and disordered lattices are fabricated of circular holes with equal filling fractions in free-standing Si membranes. Ultrafast pump and probe spectroscopy (asynchronous optical sampling) and Raman thermometry based on a novel two-laser approach are used to study the phononic properties in the gigahertz (GHz) and terahertz (THz) regime, respectively. Finite element method simulations of the phonon dispersion relation and three-dimensional displacement fields furthermore enable the unique identification of the different hypersonic vibrations. The increase of surface roughness and the introduction of short-range disorder are shown to modify the phonon dispersion and phonon coherence in the hypersonic (GHz) range without affecting the room-temperature thermal conductivity. On the basis of these findings, we suggest a criteria for predicting phonon coherence as a function of roughness and disorder.
Two-dimensional topological photonic systems
Sun, Xiao-Chen; He, Cheng; Liu, Xiao-Ping; Lu, Ming-Hui; Zhu, Shi-Ning; Chen, Yan-Feng
2017-09-01
The topological phase of matter, originally proposed and first demonstrated in fermionic electronic systems, has drawn considerable research attention in the past decades due to its robust transport of edge states and its potential with respect to future quantum information, communication, and computation. Recently, searching for such a unique material phase in bosonic systems has become a hot research topic worldwide. So far, many bosonic topological models and methods for realizing them have been discovered in photonic systems, acoustic systems, mechanical systems, etc. These discoveries have certainly yielded vast opportunities in designing material phases and related properties in the topological domain. In this review, we first focus on some of the representative photonic topological models and employ the underlying Dirac model to analyze the edge states and geometric phase. On the basis of these models, three common types of two-dimensional topological photonic systems are discussed: 1) photonic quantum Hall effect with broken time-reversal symmetry; 2) photonic topological insulator and the associated pseudo-time-reversal symmetry-protected mechanism; 3) time/space periodically modulated photonic Floquet topological insulator. Finally, we provide a summary and extension of this emerging field, including a brief introduction to the Weyl point in three-dimensional systems.
Radiation effects on two-dimensional materials
Energy Technology Data Exchange (ETDEWEB)
Walker, R.C. II; Robinson, J.A. [Department of Materials Science, Penn State, University Park, PA (United States); Center for Two-Dimensional Layered Materials, Penn State, University Park, PA (United States); Shi, T. [Department of Mechanical and Nuclear Engineering, Penn State, University Park, PA (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States); Silva, E.C. [GlobalFoundries, Malta, NY (United States); Jovanovic, I. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States)
2016-12-15
The effects of electromagnetic and particle irradiation on two-dimensional materials (2DMs) are discussed in this review. Radiation creates defects that impact the structure and electronic performance of materials. Determining the impact of these defects is important for developing 2DM-based devices for use in high-radiation environments, such as space or nuclear reactors. As such, most experimental studies have been focused on determining total ionizing dose damage to 2DMs and devices. Total dose experiments using X-rays, gamma rays, electrons, protons, and heavy ions are summarized in this review. We briefly discuss the possibility of investigating single event effects in 2DMs based on initial ion beam irradiation experiments and the development of 2DM-based integrated circuits. Additionally, beneficial uses of irradiation such as ion implantation to dope materials or electron-beam and helium-beam etching to shape materials have begun to be used on 2DMs and are reviewed as well. For non-ionizing radiation, such as low-energy photons, we review the literature on 2DM-based photo-detection from terahertz to UV. The majority of photo-detecting devices operate in the visible and UV range, and for this reason they are the focus of this review. However, we review the progress in developing 2DMs for detecting infrared and terahertz radiation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Photodetectors based on two dimensional materials
Zheng, Lou; Zhongzhu, Liang; Guozhen, Shen
2016-09-01
Two-dimensional (2D) materials with unique properties have received a great deal of attention in recent years. This family of materials has rapidly established themselves as intriguing building blocks for versatile nanoelectronic devices that offer promising potential for use in next generation optoelectronics, such as photodetectors. Furthermore, their optoelectronic performance can be adjusted by varying the number of layers. They have demonstrated excellent light absorption, enabling ultrafast and ultrasensitive detection of light in photodetectors, especially in their single-layer structure. Moreover, due to their atomic thickness, outstanding mechanical flexibility, and large breaking strength, these materials have been of great interest for use in flexible devices and strain engineering. Toward that end, several kinds of photodetectors based on 2D materials have been reported. Here, we present a review of the state-of-the-art in photodetectors based on graphene and other 2D materials, such as the graphene, transition metal dichalcogenides, and so on. Project supported by the National Natural Science Foundation of China (Nos. 61377033, 61574132, 61504136) and the State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences.
Asymptotics for Two-dimensional Atoms
DEFF Research Database (Denmark)
Nam, Phan Thanh; Portmann, Fabian; Solovej, Jan Philip
2012-01-01
We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E^{\\TF}(\\lambd......We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E......^{\\TF}(\\lambda)$ is given by a Thomas-Fermi type variational problem and $c^{\\rm H}\\approx -2.2339$ is an explicit constant. We also show that the radius of a two-dimensional neutral atom is unbounded when $Z\\to \\infty$, which is contrary to the expected behavior of three-dimensional atoms....
Predicting Two-Dimensional Silicon Carbide Monolayers.
Shi, Zhiming; Zhang, Zhuhua; Kutana, Alex; Yakobson, Boris I
2015-10-27
Intrinsic semimetallicity of graphene and silicene largely limits their applications in functional devices. Mixing carbon and silicon atoms to form two-dimensional (2D) silicon carbide (SixC1-x) sheets is promising to overcome this issue. Using first-principles calculations combined with the cluster expansion method, we perform a comprehensive study on the thermodynamic stability and electronic properties of 2D SixC1-x monolayers with 0 ≤ x ≤ 1. Upon varying the silicon concentration, the 2D SixC1-x presents two distinct structural phases, a homogeneous phase with well dispersed Si (or C) atoms and an in-plane hybrid phase rich in SiC domains. While the in-plane hybrid structure shows uniform semiconducting properties with widely tunable band gap from 0 to 2.87 eV due to quantum confinement effect imposed by the SiC domains, the homogeneous structures can be semiconducting or remain semimetallic depending on a superlattice vector which dictates whether the sublattice symmetry is topologically broken. Moreover, we reveal a universal rule for describing the electronic properties of the homogeneous SixC1-x structures. These findings suggest that the 2D SixC1-x monolayers may present a new "family" of 2D materials, with a rich variety of properties for applications in electronics and optoelectronics.
Ellis, S.; Giometti, C. S.; Riley, D. A.
1985-01-01
Using 320 g rats, a two-dimensional electrophoretic analysis of muscle proteins in the soleus and EDL muscles from hindlimbs maintained load-free for 10 days is performed. Statistical analysis of the two-dimensional patterns of control and suspended groups reveals more protein alteration in the soleus muscle, with 25 protein differences, than the EDL muscle, with 9 protein differences, as a result of atrophy. Most of the soleus differences reside in minor components. It is suggested that the EDL may also show alteration in its two-dimensional protein map, even though no significant atrophy occurred in muscle wet weight. It is cautioned that strict interpretation of data must take into account possible endocrine perturbations.
Perturbations and quantum relaxation
Kandhadai, Adithya
2016-01-01
We investigate whether small perturbations can cause relaxation to quantum equilibrium over very long timescales. We consider in particular a two-dimensional harmonic oscillator, which can serve as a model of a field mode on expanding space. We assume an initial wave function with small perturbations to the ground state. We present evidence that the trajectories are highly confined so as to preclude relaxation to equilibrium even over very long timescales. Cosmological implications are briefly discussed.
Renormalization of two-dimensional quantum electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Casana S, Rodolfo; Dias, Sebastiao A
1997-12-01
The Schwinger model, when quantized in a gauge non-invariant way exhibits a dependence on a parameter {alpha} (the Jackiw-Rajaraman parameter) in a way which is analogous to the case involving chiral fermions (the chiral Schwinger model). For all values of a {alpha}1, there are divergences in the fermionic Green`s functions. We propose a regularization of the generating functional Z [{eta}, {eta}, J] and we use it to renormalize the theory to one loop level, in a semi-perturbative sense. At the end of the renormalization procedure we find an implicit dependence of {alpha} on the renormalization scale {mu}. (author) 26 refs.
Interaction of two-dimensional magnetoexcitons
Dumanov, E. V.; Podlesny, I. V.; Moskalenko, S. A.; Liberman, M. A.
2017-04-01
We study interaction of the two-dimensional magnetoexcitons with in-plane wave vector k→∥ = 0 , taking into account the influence of the excited Landau levels (ELLs) and of the external electric field perpendicular to the surface of the quantum well and parallel to the external magnetic field. It is shown that the account of the ELLs gives rise to the repulsion between the spinless magnetoexcitons with k→∥ = 0 in the Fock approximation, with the interaction constant g decreasing inverse proportional to the magnetic field strength B (g (0) ∼ 1 / B) . In the presence of the perpendicular electric field the Rashba spin-orbit coupling (RSOC), Zeeman splitting (ZS) and nonparabolicity of the heavy-hole dispersion law affect the Landau quantization of the electrons and holes. They move along the new cyclotron orbits, change their Coulomb interactions and cause the interaction between 2D magnetoexcitons with k→∥ = 0 . The changes of the Coulomb interactions caused by the electrons and by the holes moving with new cyclotron orbits are characterized by some coefficients, which in the absence of the electric field turn to be unity. The differences between these coefficients of the electron-hole pairs forming the magnetoexcitons determine their affinities to the interactions. The interactions between the homogeneous, semihomogeneous and heterogeneous magnetoexcitons forming the symmetric states with the same signs of their affinities are attractive whereas in the case of different sign affinities are repulsive. In the heterogeneous asymmetric states the interactions have opposite signs in comparison with the symmetric states. In all these cases the interaction constant g have the dependence g (0) 1 /√{ B} .
Two-dimensional materials and their prospects in transistor electronics.
Schwierz, F; Pezoldt, J; Granzner, R
2015-05-14
During the past decade, two-dimensional materials have attracted incredible interest from the electronic device community. The first two-dimensional material studied in detail was graphene and, since 2007, it has intensively been explored as a material for electronic devices, in particular, transistors. While graphene transistors are still on the agenda, researchers have extended their work to two-dimensional materials beyond graphene and the number of two-dimensional materials under examination has literally exploded recently. Meanwhile several hundreds of different two-dimensional materials are known, a substantial part of them is considered useful for transistors, and experimental transistors with channels of different two-dimensional materials have been demonstrated. In spite of the rapid progress in the field, the prospects of two-dimensional transistors still remain vague and optimistic opinions face rather reserved assessments. The intention of the present paper is to shed more light on the merits and drawbacks of two-dimensional materials for transistor electronics and to add a few more facets to the ongoing discussion on the prospects of two-dimensional transistors. To this end, we compose a wish list of properties for a good transistor channel material and examine to what extent the two-dimensional materials fulfill the criteria of the list. The state-of-the-art two-dimensional transistors are reviewed and a balanced view of both the pros and cons of these devices is provided.
Two-dimensional equilibrium in coronal magnetostatic flux tubes: an accurate equilibrium solver
Belien, A. J. C.; Poedts, S.; Goedbloed, J. P.
1997-01-01
To study linearized magnetohydrodynamic (MHD) waves, continuous spectra, and instabilities in coronal magnetic flux tubes that are anchored in dense chromospheric and photospheric regions, a two-dimensional numerical code, called PARIS, has been developed. PARIS solves the pertinent nonlinear Grad-S
Internetwork magnetic field as revealed by two-dimensional inversions
Danilovic, S.; van Noort, M.; Rempel, M.
2016-09-01
Context. Properties of magnetic field in the internetwork regions are still fairly unknown because of rather weak spectropolarimetric signals. Aims: We address the matter by using the two-dimensional (2D) inversion code, which is able to retrieve the information on smallest spatial scales up to the diffraction limit, while being less susceptible to noise than most of the previous methods used. Methods: Performance of the code and the impact of various effects on the retrieved field distribution is tested first on the realistic magneto-hydrodynamic (MHD) simulations. The best inversion scenario is then applied to the real data obtained by Spectropolarimeter (SP) on board Hinode. Results: Tests on simulations show that: (1) the best choice of node position ensures a decent retrieval of all parameters; (2) the code performs well for different configurations of magnetic field; (3) slightly different noise levels or slightly different defocus included in the spatial point spread function (PSF) produces no significant effect on the results; and (4) temporal integration shifts the field distribution to a stronger, more horizontally inclined field. Conclusions: Although the contribution of the weak field is slightly overestimated owing to noise, 2D inversions are able to recover well the overall distribution of the magnetic field strength. Application of the 2D inversion code on the Hinode SP internetwork observations reveals a monotonic field strength distribution. The mean field strength at optical depth unity is ~ 130 G. At higher layers, field strength drops as the field becomes more horizontal. Regarding the distribution of the field inclination, tests show that we cannot directly retrieve it with the observations and tools at hand, however, the obtained distributions are consistent with those expected from simulations with a quasi-isotropic field inclination after accounting for observational effects.
Optimal Padding for the Two-Dimensional Fast Fourier Transform
Dean, Bruce H.; Aronstein, David L.; Smith, Jeffrey S.
2011-01-01
One-dimensional Fast Fourier Transform (FFT) operations work fastest on grids whose size is divisible by a power of two. Because of this, padding grids (that are not already sized to a power of two) so that their size is the next highest power of two can speed up operations. While this works well for one-dimensional grids, it does not work well for two-dimensional grids. For a two-dimensional grid, there are certain pad sizes that work better than others. Therefore, the need exists to generalize a strategy for determining optimal pad sizes. There are three steps in the FFT algorithm. The first is to perform a one-dimensional transform on each row in the grid. The second step is to transpose the resulting matrix. The third step is to perform a one-dimensional transform on each row in the resulting grid. Steps one and three both benefit from padding the row to the next highest power of two, but the second step needs a novel approach. An algorithm was developed that struck a balance between optimizing the grid pad size with prime factors that are small (which are optimal for one-dimensional operations), and with prime factors that are large (which are optimal for two-dimensional operations). This algorithm optimizes based on average run times, and is not fine-tuned for any specific application. It increases the amount of times that processor-requested data is found in the set-associative processor cache. Cache retrievals are 4-10 times faster than conventional memory retrievals. The tested implementation of the algorithm resulted in faster execution times on all platforms tested, but with varying sized grids. This is because various computer architectures process commands differently. The test grid was 512 512. Using a 540 540 grid on a Pentium V processor, the code ran 30 percent faster. On a PowerPC, a 256x256 grid worked best. A Core2Duo computer preferred either a 1040x1040 (15 percent faster) or a 1008x1008 (30 percent faster) grid. There are many industries that
Image encryption using the two-dimensional logistic chaotic map
Wu, Yue; Yang, Gelan; Jin, Huixia; Noonan, Joseph P.
2012-01-01
Chaos maps and chaotic systems have been proved to be useful and effective for cryptography. In our study, the two-dimensional logistic map with complicated basin structures and attractors are first used for image encryption. The proposed method adopts the classic framework of the permutation-substitution network in cryptography and thus ensures both confusion and diffusion properties for a secure cipher. The proposed method is able to encrypt an intelligible image into a random-like one from the statistical point of view and the human visual system point of view. Extensive simulation results using test images from the USC-SIPI image database demonstrate the effectiveness and robustness of the proposed method. Security analysis results of using both the conventional and the most recent tests show that the encryption quality of the proposed method reaches or excels the current state-of-the-art methods. Similar encryption ideas can be applied to digital data in other formats (e.g., digital audio and video). We also publish the cipher MATLAB open-source-code under the web page https://sites.google.com/site/tuftsyuewu/source-code.
WAVE PROPAGATION IN TWO-DIMENSIONAL DISORDERED PIEZOELECTRIC PHONONIC CRYSTALS
Institute of Scientific and Technical Information of China (English)
Jinqiang Li; Fengming Li; Yuesheng Wang; Kikuo Kishimoto
2008-01-01
The wave propagation is studied in two-dimensional disordered piezoelectric phononie crystals using the finite-difference time-domain (FDTD) method. For different eases of disorder,the transmission coefficients are calculated. The influences of disorders on band gaps are investigated. The results show that the disorder in the piezoelectric phononic crystals has more significant influences on the band gap in the low frequency regions than in the high frequency ones. The relation between the width of band gap and the direction of position disorder is also discussed. When the position disorder is along the direction perpendicular to the wave transmission, the piezoelectric phononic crystals have wider band gaps at low frequency regions than the case of position disorder being along the wave transmission direction. It can also be found that the effect of. size disorder on band gaps is analogous to that of location disorder. When the perturbation coefficient is big, it has more pronounced effects on the pass bands in the piezoelectric phononic crystals with both size and location disorders than in the piezoelectric phononic crystals with single disorder.In higher frequency regions the piezoelectric effect reduces the transmission coefficients. But for larger disorder degree, the effects of the piezoelectricity will be reduced.
Ab Initio Prediction of Piezoelectricity in Two-Dimensional Materials.
Blonsky, Michael N; Zhuang, Houlong L; Singh, Arunima K; Hennig, Richard G
2015-10-27
Two-dimensional (2D) materials present many unique materials concepts, including material properties that sometimes differ dramatically from those of their bulk counterparts. One of these properties, piezoelectricity, is important for micro- and nanoelectromechanical systems applications. Using symmetry analysis, we determine the independent piezoelectric coefficients for four groups of predicted and synthesized 2D materials. We calculate with density-functional perturbation theory the stiffness and piezoelectric tensors of these materials. We determine the in-plane piezoelectric coefficient d11 for 37 materials within the families of 2D metal dichalcogenides, metal oxides, and III-V semiconductor materials. A majority of the structures, including CrSe2, CrTe2, CaO, CdO, ZnO, and InN, have d11 coefficients greater than 5 pm/V, a typical value for bulk piezoelectric materials. Our symmetry analysis shows that buckled 2D materials exhibit an out-of-plane coefficient d31. We find that d31 for 8 III-V semiconductors ranges from 0.02 to 0.6 pm/V. From statistical analysis, we identify correlations between the piezoelectric coefficients and the electronic and structural properties of the 2D materials that elucidate the origin of the piezoelectricity. Among the 37 2D materials, CdO, ZnO, and CrTe2 stand out for their combination of large piezoelectric coefficient and low formation energy and are recommended for experimental exploration.
Subsurface imaging of two-dimensional materials at the nanoscale
Dinelli, Franco; Pingue, Pasqualantonio; Kay, Nicholas D.; Kolosov, Oleg V.
2017-02-01
Scanning probe microscopy (SPM) represents a powerful tool that, in the past 30 years, has allowed for the investigation of material surfaces in unprecedented ways at the nanoscale level. However, SPM has shown very little capability for depth penetration, which several nanotechnology applications require. Subsurface imaging has been achieved only in a few cases, when subsurface features influence the physical properties of the surface, such as the electronic states or the heat transfer. Ultrasonic force microscopy (UFM), an adaption of the contact mode atomic force microscopy, can dynamically measure the stiffness of the elastic contact between the probing tip and the sample surface. In particular, UFM has proven highly sensitive to the near-surface elastic field in non-homogeneous samples. In this paper, we present an investigation of two-dimensional (2D) materials, namely flakes of graphite and molybdenum disulphide placed on structured polymeric substrates. We show that UFM can non-destructively distinguish suspended and supported areas and localise defects, such as buckling or delamination of adjacent monolayers, generated by residual stress. Specifically, UFM can probe small variations in the local indentation induced by the mechanical interaction between the tip and the sample. Therefore, any change in the elastic modulus within the volume perturbed by the applied load or the flexural bending of the suspended areas can be detected and imaged. These investigation capabilities are very promising in order to study the buried interfaces of nanostructured 2D materials such as in graphene-based devices.
Two-dimensional Nutation Echo Nuclear Quadrupole Resonance Spectroscopy
Harbison, Gerard S.; Slokenbergs, Andris
1990-04-01
We discuss two new two-dimensional nuclear quadrupole resonance experiments, both based on the principle of nutation spectroscopy, which can be used to determine the asymmetry parameter, and thus the full quadrupolar tensor, of spin-3/2 nuclei at zero applied magnetic field. The first experiment is a simple nutation pulse sequence in which the first time period (t1) is the duration of the radiofrequency exciting pulse; and the second (t2) is the normal free-precession of a quadrupolar nucleus at zero-field. After double Fourier-transformation, the result is a 2 D spectrum in which the first frequency dimension is the nutation spectrum for the quadrupolar nucleus at zero-field. For polycrystalline samples this sequence generates powder lineshapes; the position of the singularities, in these lineshapes can be used to determine the asymmetry parameters η in a very straightforward manner, η has previously only been obtainable using Zeeman perturbed NQR methods. The second sequence is the same nutation experiment with a spin-echo pulse added. The virtue of this refocussing pulse is that it allows acquisition of nutation spectra from samples with arbitrary inhomogeneous linewidth; thus, asymmetry parameters can be determined even where the quadrupolar resonance is wider than the bandwidth of the spectrometer. Experimental examples of 35Cl, 81Br and 63Cu nutation and nutation-echo spectra are presented.
Improvement in two-dimensional barcode
Indian Academy of Sciences (India)
SONAM WASULE; SHILPA METKAR
2017-07-01
Barcode is one of the existing systems which is very fast in scanning and more accurate when compared with other coding systems. It is extensively used because speed of scanning the barcode is very high as compared with manual data entry. To increase the capacity of 2D monochrome QR code to 3 fold, 2D colour QR code is developed. The challenge in the development of colour barcode is in its decoding, since the intensity and depth of colours vary during the printing and scanning process. We need to understand the decoding process and make it insensitive to such variations. A lot of work has been already done to deal with such variations but acceptable results have not yet been achieved. The objective behind colour barcode is to increase the capacity to 3 fold as compared with 2D monochrome barcode. In this paper we proposed a novel approach that will increase the capacity of barcode beyond 3 fold and deals with decoding problem of intensity variation. In the proposed technique, quantization of grey levels is specified to handle the problem of intensity variation.
Ultrafast two dimensional infrared chemical exchange spectroscopy
Fayer, Michael
2011-03-01
The method of ultrafast two dimensional infrared (2D IR) vibrational echo spectroscopy is described. Three ultrashort IR pulses tuned to the frequencies of the vibrational transitions of interest are directed into the sample. The interaction of these pulses with the molecular vibrational oscillators produces a polarization that gives rise to a fourth pulse, the vibrational echo. The vibrational echo pulse is combined with another pulse, the local oscillator, for heterodyne detection of the signal. For fixed time between the second and third pulses, the waiting time, the first pulse is scanned. Two Fourier transforms of the data yield a 2D IR spectrum. The waiting time is increased, and another spectrum is obtained. The change in the 2D IR spectra with increased waiting time provides information on the time evolution of the structure of the molecular system under observation. In a 2D IR chemical exchange experiment, two species A and B, are undergoing chemical exchange. A's are turning into B's, and B's are turning into A's, but the overall concentrations of the species are not changing. The kinetics of the chemical exchange on the ground electronic state under thermal equilibrium conditions can be obtained 2D IR spectroscopy. A vibration that has a different frequency for the two species is monitored. At very short time, there will be two peaks on the diagonal of the 2D IR spectrum, one for A and one for B. As the waiting time is increased, chemical exchange causes off-diagonal peaks to grow in. The time dependence of the growth of these off-diagonal peaks gives the chemical exchange rate. The method is applied to organic solute-solvent complex formation, orientational isomerization about a carbon-carbon single bond, migration of a hydrogen bond from one position on a molecule to another, protein structural substate interconversion, and water hydrogen bond switching between ions and water molecules. This work was supported by the Air Force Office of Scientific
Molecular assembly on two-dimensional materials
Kumar, Avijit; Banerjee, Kaustuv; Liljeroth, Peter
2017-02-01
Molecular self-assembly is a well-known technique to create highly functional nanostructures on surfaces. Self-assembly on two-dimensional (2D) materials is a developing field driven by the interest in functionalization of 2D materials in order to tune their electronic properties. This has resulted in the discovery of several rich and interesting phenomena. Here, we review this progress with an emphasis on the electronic properties of the adsorbates and the substrate in well-defined systems, as unveiled by scanning tunneling microscopy. The review covers three aspects of the self-assembly. The first one focuses on non-covalent self-assembly dealing with site-selectivity due to inherent moiré pattern present on 2D materials grown on substrates. We also see that modification of intermolecular interactions and molecule–substrate interactions influences the assembly drastically and that 2D materials can also be used as a platform to carry out covalent and metal-coordinated assembly. The second part deals with the electronic properties of molecules adsorbed on 2D materials. By virtue of being inert and possessing low density of states near the Fermi level, 2D materials decouple molecules electronically from the underlying metal substrate and allow high-resolution spectroscopy and imaging of molecular orbitals. The moiré pattern on the 2D materials causes site-selective gating and charging of molecules in some cases. The last section covers the effects of self-assembled, acceptor and donor type, organic molecules on the electronic properties of graphene as revealed by spectroscopy and electrical transport measurements. Non-covalent functionalization of 2D materials has already been applied for their application as catalysts and sensors. With the current surge of activity on building van der Waals heterostructures from atomically thin crystals, molecular self-assembly has the potential to add an extra level of flexibility and functionality for applications ranging
Scattering of Fexural Gravity Waves by a Two-Dimensional Thin Plate
Directory of Open Access Journals (Sweden)
Sudeshna Banerjee
2017-01-01
Full Text Available An approximate analysis based on standard perturbation technique together with an application of Green’s integral theorem is used in this paper to study the problem of scattering of water waves by a two dimensional thin plate submerged in deep ocean with ice cover. The reﬂection and transmission coefﬁcients upto ﬁrst order are obtained in terms of the shape function describing the plate and are studied graphically for different shapes of the plate.
Truchet, G.; Leconte, P.; Peneliau, Y.; Santamarina, A.; Malvagi, F.
2014-06-01
Pile-oscillation experiments are performed in the MINERVE reactor at the CEA Cadarache to improve nuclear data accuracy. In order to precisely calculate small reactivity variations (experiments, a reference calculation need to be achieved. This calculation may be accomplished using the continuous-energy Monte Carlo code TRIPOLI-4® by using the eigenvalue difference method. This "direct" method has shown limitations in the evaluation of very small reactivity effects because it needs to reach a very small variance associated to the reactivity in both states. To answer this problem, it has been decided to implement the exact perturbation theory in TRIPOLI-4® and, consequently, to calculate a continuous-energy adjoint flux. The Iterated Fission Probability (IFP) method was chosen because it has shown great results in some other Monte Carlo codes. The IFP method uses a forward calculation to compute the adjoint flux, and consequently, it does not rely on complex code modifications but on the physical definition of the adjoint flux as a phase-space neutron importance. In the first part of this paper, the IFP method implemented in TRIPOLI-4® is described. To illustrate the effciency of the method, several adjoint fluxes are calculated and compared with their equivalent obtained by the deterministic code APOLLO-2. The new implementation can calculate angular adjoint flux. In the second part, a procedure to carry out an exact perturbation calculation is described. A single cell benchmark has been used to test the accuracy of the method, compared with the "direct" estimation of the perturbation. Once again the method based on the IFP shows good agreement for a calculation time far more inferior to the "direct" method. The main advantage of the method is that the relative accuracy of the reactivity variation does not depend on the magnitude of the variation itself, which allows us to calculate very small reactivity perturbations with high precision. Other applications of
Huang, Xueqin; Zhang, Zhao-Qing; Chan, C T
2014-01-01
There is no assurance that interface states can be found at the boundary separating two materials. As a strong perturbation typically favors wave localization, it is natural to expect that an interface state should form more easily in the boundary that represents a strong perturbation. Here, we show on the contrary that in some two dimensional photonic crystals (PCs) with a square lattice possessing Dirac-like cone at k=0, a small perturbation guarantees the existence of interface states. More specifically, we find that single-mode localized states exist in a deterministic manner at an interface formed by two PCs each with system parameters slightly perturbed from the conical dispersion condition. The conical dispersion guarantees the existence of gaps in the projected band structure which allows interface states to form and the assured existence of interface states stems from the geometric phases of the bulk bands.
Resonant state expansion applied to two-dimensional open optical systems
Doost, M B; Muljarov, E A
2013-01-01
The resonant state expansion (RSE), a rigorous perturbative method in electrodynamics, is applied to two-dimensional open optical systems. The analytically solvable homogeneous dielectric cylinder is used as unperturbed system, and its Green's function is shown to contain a cut in the complex frequency plane, which is included in the RSE basis. The complex eigenfrequencies of modes are calculated using the RSE for a selection of perturbations which mix unperturbed modes of different orbital momentum, such as half-cylinder, thin-film and thin-wire perturbation, demonstrating the accuracy and convergency of the method. The resonant states for the thin-wire perturbation are shown to reproduce an approximative analytical solution.
The convolution theorem for two-dimensional continuous wavelet transform
Institute of Scientific and Technical Information of China (English)
ZHANG CHI
2013-01-01
In this paper , application of two -dimensional continuous wavelet transform to image processes is studied. We first show that the convolution and correlation of two continuous wavelets satisfy the required admissibility and regularity conditions ,and then we derive the convolution and correlation theorem for two-dimensional continuous wavelet transform. Finally, we present numerical example showing the usefulness of applying the convolution theorem for two -dimensional continuous wavelet transform to perform image restoration in the presence of additive noise.
Fission-gas release at extended burnups: effect of two-dimensional heat transfer
Energy Technology Data Exchange (ETDEWEB)
Tayal, M. [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada); Yu, S.D. [Ryerson Polytechnic Univ., Toronto, Ontario (Canada); Lau, J.H.K
2000-09-01
To better simulate the performance of high-burnup CANDU fuel, a two-dimensional model for heat transfer between the pellet and the sheath has been added to the computer code ELESTRES. The model covers four relative orientations of the pellet and the sheath and their impacts on heat transfer and fission-gas release. The predictions of the code were compared to a database of 27 experimental irradiations involving extended burnups and normal burnups. The calculated values of fission gas release matched the measurements to an average of 94%. Thus, the two-dimensional heat transfer model increases the versatility of the ELESTRES code to better simulate fuels at normal as well as at extended burnups. (author)
Two dimensional simulation of high power laser-surface interaction
Energy Technology Data Exchange (ETDEWEB)
Goldman, S.R.; Wilke, M.D.; Green, R.E.L.; Johnson, R.P. [Los Alamos National Lab., NM (United States); Busch, G.E. [KMS Fusion, Inc., Ann Arbor, MI (United States)
1998-08-01
For laser intensities in the range of 10{sup 8}--10{sup 9} W/cm{sup 2}, and pulse lengths of order 10 {micro}sec or longer, the authors have modified the inertial confinement fusion code Lasnex to simulate gaseous and some dense material aspects of the laser-matter interaction. The unique aspect of their treatment consists of an ablation model which defines a dense material-vapor interface and then calculates the mass flow across this interface. The model treats the dense material as a rigid two-dimensional mass and heat reservoir suppressing all hydrodynamic motion in the dense material. The computer simulations and additional post-processors provide predictions for measurements including impulse given to the target, pressures at the target interface, electron temperatures and densities in the vapor-plasma plume region, and emission of radiation from the target. The authors will present an analysis of some relatively well diagnosed experiments which have been useful in developing their modeling. The simulations match experimentally obtained target impulses, pressures at the target surface inside the laser spot, and radiation emission from the target to within about 20%. Hence their simulational technique appears to form a useful basis for further investigation of laser-surface interaction in this intensity, pulse-width range. This work is useful in many technical areas such as materials processing.
Development of two-dimensional hot pool model
Energy Technology Data Exchange (ETDEWEB)
Lee, Yong Bum; Hahn, H. D
2000-05-01
During a normal reactor scram, the heat generation is reduced almost instantaneously while the coolant flow rate follows the pump coast-down. This mismatch between power and flow results in a situation where the core flow entering the hot pool is at a lower temperature than the temperature of the bulk pool sodium. This temperature difference leads to thermal stratification. Thermal stratification can occur in the hot pool region if the entering coolant is colder than the existing hot pool coolant and the flow momentum is not large enough to overcome the negative buoyancy force. Since the fluid of hot pool enters IHX{sub s}, the temperature distribution of hot pool can alter the overall system response. Hence, it is necessary to predict the pool coolant temperature distribution with sufficient accuracy to determine the inlet temperature conditions for the IHX{sub s} and its contribution to the net buoyancy head. Therefore, in this study two-dimensional hot pool model is developed instead of existing one-dimensional model to predict the hot pool coolant temperature and velocity distribution more accurately and is applied to the SSC-K code.
Two-dimensional audio watermark for MPEG AAC audio
Tachibana, Ryuki
2004-06-01
Since digital music is often stored in a compressed file, it is desirable that an audio watermarking method in a content management system handles compressed files. Using an audio watermarking method that directly manipulates compressed files makes it unnecessary to decompress the files before embedding or detection, so more files can be processed per unit time. However, it is difficult to detect a watermark in a compressed file that has been compressed after the file was watermarked. This paper proposes an MPEG Advanced Audio Coding (AAC) bitstream watermarking method using a two-dimensional pseudo-random array. Detection is done by correlating the absolute values of the recovered MDCT coefficients and the pseudo-random array. Since the embedding algorithm uses the same pseudo-random values for two adjacent overlapping frames and the detection algorithm selects the better frame in the two by comparing detected watermark strengths, it is possible to detect a watermark from a compressed file that was compressed after the watermark was embedded in the original uncompressed file. Though the watermark is not detected as clearly in this case, the watermark can still be detected even when the watermark was embedded in a compressed file and the file was then decompressed, trimmed, and compressed again.
The Chandrasekhar's Equation for Two-Dimensional Hypothetical White Dwarfs
De, Sanchari
2014-01-01
In this article we have extended the original work of Chandrasekhar on the structure of white dwarfs to the two-dimensional case. Although such two-dimensional stellar objects are hypothetical in nature, we strongly believe that the work presented in this article may be prescribed as Master of Science level class problem for the students in physics.
Beginning Introductory Physics with Two-Dimensional Motion
Huggins, Elisha
2009-01-01
During the session on "Introductory College Physics Textbooks" at the 2007 Summer Meeting of the AAPT, there was a brief discussion about whether introductory physics should begin with one-dimensional motion or two-dimensional motion. Here we present the case that by starting with two-dimensional motion, we are able to introduce a considerable…
Spatiotemporal surface solitons in two-dimensional photonic lattices.
Mihalache, Dumitru; Mazilu, Dumitru; Lederer, Falk; Kivshar, Yuri S
2007-11-01
We analyze spatiotemporal light localization in truncated two-dimensional photonic lattices and demonstrate the existence of two-dimensional surface light bullets localized in the lattice corners or the edges. We study the families of the spatiotemporal surface solitons and their properties such as bistability and compare them with the modes located deep inside the photonic lattice.
Explorative data analysis of two-dimensional electrophoresis gels
DEFF Research Database (Denmark)
Schultz, J.; Gottlieb, D.M.; Petersen, Marianne Kjerstine;
2004-01-01
Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening...
Mechanics of Apparent Horizon in Two Dimensional Dilaton Gravity
Cai, Rong-Gen
2016-01-01
In this article, we give a definition of apparent horizon in a two dimensional general dilaton gravity theory. With this definition, we construct the mechanics of the apparent horizon by introducing a quasi-local energy of the theory. Our discussion generalizes the apparent horizons mechanics in general spherically symmetric spactimes in four or higher dimensions to the two dimensional dilaton gravity case.
Topological aspect of disclinations in two-dimensional crystals
Institute of Scientific and Technical Information of China (English)
Qi Wei-Kai; Zhu Tao; Chen Yong; Ren Ji-Rong
2009-01-01
By using topological current theory, this paper studies the inner topological structure of disclinations during the melting of two-dimensional systems. From two-dimensional elasticity theory, it finds that there are topological currents for topological defects in homogeneous equation. The evolution of disclinations is studied, and the branch conditions for generating, annihilating, crossing, splitting and merging of disclinations are given.
Status for the two-dimensional Navier-Stokes solver EllipSys2D
DEFF Research Database (Denmark)
Bertagnolio, F.; Sørensen, Niels N.; Johansen, J.
2001-01-01
This report sets up an evaluation of the two-dimensional Navier-Stokes solver EllipSys2D in its present state. This code is used for blade aerodynamics simulations in the Aeroelastic Design group at Risø. Two airfoils are investigated by computing theflow at several angles of attack ranging from...... the linear to the stalled region. The computational data are compared to experimental data and numerical results from other computational codes. Several numerical aspects are studied, as mesh dependency,convective scheme, steady state versus unsteady computations, transition modelling. Some general...... conclusions intended to help in using this code for numerical simulations are given....
Invariant Subspaces of the Two-Dimensional Nonlinear Evolution Equations
Directory of Open Access Journals (Sweden)
Chunrong Zhu
2016-11-01
Full Text Available In this paper, we develop the symmetry-related methods to study invariant subspaces of the two-dimensional nonlinear differential operators. The conditional Lie–Bäcklund symmetry and Lie point symmetry methods are used to construct invariant subspaces of two-dimensional differential operators. We first apply the multiple conditional Lie–Bäcklund symmetries to derive invariant subspaces of the two-dimensional operators. As an application, the invariant subspaces for a class of two-dimensional nonlinear quadratic operators are provided. Furthermore, the invariant subspace method in one-dimensional space combined with the Lie symmetry reduction method and the change of variables is used to obtain invariant subspaces of the two-dimensional nonlinear operators.
Lacivita, Valentina; Rérat, Michel; Kirtman, Bernard; Ferrero, Mauro; Orlando, Roberto; Dovesi, Roberto
2009-11-01
The high-frequency dielectric ɛ and the first nonlinear electric susceptibility χ(2) tensors of crystalline potassium dihydrogen phosphate (KH2PO4) are calculated by using the coupled perturbed Hartree-Fock and Kohn-Sham methods as implemented in the CRYSTAL code. The effect of basis sets of increasing size on ɛ and χ(2) is explored. Five different levels of theory, namely, local-density approximation, generalized gradient approximation (PBE), hybrids (B3LYP and PBE0), and HF are compared using the experimental and theoretical structures corresponding not only to the tetragonal geometry I4d2 at room temperature but also to the orthorhombic phase Fdd2 at low temperature. Comparison between the two phases and their optical behavior is made. The calculated results for the tetragonal phase are in good agreement with the experimental data.
Two-dimensional discrete gap breathers in a two-dimensional discrete diatomic Klein-Gordon lattice
Institute of Scientific and Technical Information of China (English)
XU Quan; QIANG Tian
2009-01-01
We study the existence and stability of two-dimensional discrete breathers in a two-dimensional discrete diatomic Klein-Gordon lattice consisting of alternating light and heavy atoms, with nearest-neighbor harmonic coupling.Localized solutions to the corresponding nonlinear differential equations with frequencies inside the gap of the linear wave spectrum, i.e. two-dimensional gap breathers, are investigated numerically. The numerical results of the corresponding algebraic equations demonstrate the possibility of the existence of two-dimensional gap breathers with three types of symmetries, i.e., symmetric, twin-antisymmetric and single-antisymmetric. Their stability depends on the nonlinear on-site potential (soft or hard), the interaction potential (attractive or repulsive)and the center of the two-dimensional gap breather (on a light or a heavy atom).
Spherical-shell boundaries for two-dimensional compressible convection in a star
Pratt, J; Goffrey, T; Geroux, C; Viallet, M; Folini, D; Constantino, T; Popov, M; Walder, R
2016-01-01
Context: We study the impact of two-dimensional spherical shells on compressible convection. Realistic profiles for density and temperature from a one-dimensional stellar evolution code are used to produce a model of a large stellar convection zone representative of a young low-mass star. Methods: We perform hydrodynamic implicit large-eddy simulations of compressible convection using the MUltidimensional Stellar Implicit Code (MUSIC). Because MUSIC has been designed to use realistic stellar models produced from one-dimensional stellar evolution calculations, MUSIC simulations are capable of seamlessly modeling a whole star. Simulations in two-dimensional spherical shells that have different radial extents are performed over hundreds of convective turnover times, permitting the collection of well-converged statistics. Results: We evaluate basic statistics of the convective turnover time, the convective velocity, and the overshooting layer. These quantities are selected for their relevance to one-dimensional s...
Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway
2012-09-01
ER D C/ CH L TR -1 2 -2 0 Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway C oa st al a n d H yd ra u lic s La b or at...distribution is unlimited. ERDC/CHL TR-12-20 September 2012 Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway Stephen H. Scott, Jeremy A...A two-dimensional Adaptive Hydraulics (AdH) hydrodynamic model was developed to simulate the Moose Creek Floodway. The Floodway is located
RESEARCH ON TWO-DIMENSIONAL LDA FOR FACE RECOGNITION
Institute of Scientific and Technical Information of China (English)
Han Ke; Zhu Xiuchang
2006-01-01
The letter presents an improved two-dimensional linear discriminant analysis method for feature extraction. Compared with the current two-dimensional methods for feature extraction, the improved two-dimensional linear discriminant analysis method makes full use of not only the row and the column direction information of face images but also the discriminant information among different classes. The method is evaluated using the Nanjing University of Science and Technology (NUST) 603 face database and the Aleix Martinez and Robert Benavente (AR) face database. Experimental results show that the method in the letter is feasible and effective.
ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES
Directory of Open Access Journals (Sweden)
Nikola Stefanović
2007-06-01
Full Text Available In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic leadership style, leadership theory researchers use two dimensional matrices. The two-dimensional matrices define leadership styles on the basis of different parameters. By using these parameters, one can identify two-dimensional styles.
Development of Particle-in-Cell Simulation in a Two Dimensional Trench Geometry
Lin, Tai-Lu
2016-01-01
A two dimensional electrostatic Particle-in-Cell simulation code is developed to investigate anisotropy of ions in a trench geometry for plasma etching. The numerical simulation results suggest that if the trench width is larger than Debye length scale, anisotropy can be lost due to potential development across the trench. Furthermore, the effects of ion charge build up on the trench bottom is investigated, which can degrade the anisotropy.
Two-Dimensional Simulation of Left-Handed Metamaterial Flat Lens Using Remcon XFDTD
Wilson, Jeffrey D.; Reinert, Jason M.
2006-01-01
Remcom's XFDTD software was used to model the properties of a two-dimensional left-handed metamaterial (LHM) flat lens. The focusing capability and attenuation of the material were examined. The results showed strong agreement with experimental results and theoretical predictions of focusing effects and focal length. The inherent attenuation in the model corresponds well with the experimental results and implies that the code does a reasonably accurate job of modeling the actual metamaterial.
Kumar, Manish; Atkins, Joshua; Cairns, Murray; Ali, Ayesha; Tanwar, Pradeep S.
2016-01-01
Dysregulated Wnt signalling is associated with human infertility and testicular cancer. However, the role of Wnt signalling in male germ cells remains poorly understood. In this study, we first confirmed the activity of Wnt signalling in mouse, dog and human testes. To determine the physiological importance of the Wnt pathway, we developed a mouse model with germ cell-specific constitutive activation of βcatenin. In young mutants, similar to controls, germ cell development was normal. However, with age, mutant testes showed defective spermatogenesis, progressive germ cell loss, and flawed meiotic entry of spermatogonial cells. Flow sorting confirmed reduced germ cell populations at the leptotene/zygotene stages of meiosis in mutant group. Using thymidine analogues-based DNA double labelling technique, we further established decline in germ cell proliferation and differentiation. Overactivation of Wnt/βcatenin signalling in a spermatogonial cell line resulted in reduced cell proliferation, viability and colony formation. RNA sequencing analysis of testes revealed significant alterations in the non-coding regions of mutant mouse genome. One of the novel non-coding RNAs was switched on in mutant testes compared to controls. QPCR analysis confirmed upregulation of this unique non-coding RNA in mutant testis. In summary, our results highlight the significance of Wnt signalling in male germ cells. PMID:27992363
A Two-Dimensional MagnetoHydrodynamics Scheme for General Unstructured Grids
Livne, E; Burrows, A; Meakin, C A; Livne, Eli; Dessart, Luc; Burrows, Adam; Meakin, Casey A.
2007-01-01
We report a new finite-difference scheme for two-dimensional magnetohydrodynamics (MHD) simulations, with and without rotation, in unstructured grids with quadrilateral cells. The new scheme is implemented within the code VULCAN/2D, which already includes radiation-hydrodynamics in various approximations and can be used with arbitrarily moving meshes (ALE). The MHD scheme, which consists of cell-centered magnetic field variables, preserves the nodal finite difference representation of $div(\\bB)$ by construction, and therefore any initially divergence-free field remains divergence-free through the simulation. In this paper, we describe the new scheme in detail and present comparisons of VULCAN/2D results with those of the code ZEUS/2D for several one-dimensional and two-dimensional test problems. The code now enables two-dimensional simulations of the collapse and explosion of the rotating, magnetic cores of massive stars. Moreover, it can be used to simulate the very wide variety of astrophysical problems for...
A study of two-dimensional magnetic polaron
Institute of Scientific and Technical Information of China (English)
LIU; Tao; ZHANG; Huaihong; FENG; Mang; WANG; Kelin
2006-01-01
By using the variational method and anneal simulation, we study in this paper the self-trapped magnetic polaron (STMP) in two-dimensional anti-ferromagnetic material and the bound magnetic polaron (BMP) in ferromagnetic material. Schwinger angular momentum theory is applied to changing the problem into a coupling problem of carriers and two types of Bosons. Our calculation shows that there are single-peak and multi-peak structures in the two-dimensional STMP. For the ferromagnetic material, the properties of the two-dimensional BMP are almost the same as that in one-dimensional case; but for the anti-ferromagnetic material, the two-dimensional STMP structure is much richer than the one-dimensional case.
UPWIND DISCONTINUOUS GALERKIN METHODS FOR TWO DIMENSIONAL NEUTRON TRANSPORT EQUATIONS
Institute of Scientific and Technical Information of China (English)
袁光伟; 沈智军; 闫伟
2003-01-01
In this paper the upwind discontinuous Galerkin methods with triangle meshes for two dimensional neutron transport equations will be studied.The stability for both of the semi-discrete and full-discrete method will be proved.
Two-Dimensionally-Modulated, Magnetic Structure of Neodymium Metal
DEFF Research Database (Denmark)
Lebech, Bente; Bak, P.
1979-01-01
The incipient magnetic order of dhcp Nd is described by a two-dimensional, incommensurably modulated structure ("triple-q" structure). The ordering is accompanied by a lattice distortion that forms a similar pattern....
Entanglement Entropy for time dependent two dimensional holographic superconductor
Mazhari, N S; Myrzakulov, Kairat; Myrzakulov, R
2016-01-01
We studied entanglement entropy for a time dependent two dimensional holographic superconductor. We showed that the conserved charge of the system plays the role of the critical parameter to have condensation.
Decoherence in a Landau Quantized Two Dimensional Electron Gas
Directory of Open Access Journals (Sweden)
McGill Stephen A.
2013-03-01
Full Text Available We have studied the dynamics of a high mobility two-dimensional electron gas as a function of temperature. The presence of satellite reflections in the sample and magnet can be modeled in the time-domain.
Quantization of Two-Dimensional Gravity with Dynamical Torsion
Lavrov, P M
1999-01-01
We consider two-dimensional gravity with dynamical torsion in the Batalin - Vilkovisky and Batalin - Lavrov - Tyutin formalisms of gauge theories quantization as well as in the background field method.
Spatiotemporal dissipative solitons in two-dimensional photonic lattices.
Mihalache, Dumitru; Mazilu, Dumitru; Lederer, Falk; Kivshar, Yuri S
2008-11-01
We analyze spatiotemporal dissipative solitons in two-dimensional photonic lattices in the presence of gain and loss. In the framework of the continuous-discrete cubic-quintic Ginzburg-Landau model, we demonstrate the existence of novel classes of two-dimensional spatiotemporal dissipative lattice solitons, which also include surface solitons located in the corners or at the edges of the truncated two-dimensional photonic lattice. We find the domains of existence and stability of such spatiotemporal dissipative solitons in the relevant parameter space, for both on-site and intersite lattice solitons. We show that the on-site solitons are stable in the whole domain of their existence, whereas most of the intersite solitons are unstable. We describe the scenarios of the instability-induced dynamics of dissipative solitons in two-dimensional lattices.
Bound states of two-dimensional relativistic harmonic oscillators
Institute of Scientific and Technical Information of China (English)
Qiang Wen-Chao
2004-01-01
We give the exact normalized bound state wavefunctions and energy expressions of the Klein-Gordon and Dirac equations with equal scalar and vector harmonic oscillator potentials in the two-dimensional space.
A two-dimensional polymer prepared by organic synthesis.
Kissel, Patrick; Erni, Rolf; Schweizer, W Bernd; Rossell, Marta D; King, Benjamin T; Bauer, Thomas; Götzinger, Stephan; Schlüter, A Dieter; Sakamoto, Junji
2012-02-05
Synthetic polymers are widely used materials, as attested by a production of more than 200 millions of tons per year, and are typically composed of linear repeat units. They may also be branched or irregularly crosslinked. Here, we introduce a two-dimensional polymer with internal periodicity composed of areal repeat units. This is an extension of Staudinger's polymerization concept (to form macromolecules by covalently linking repeat units together), but in two dimensions. A well-known example of such a two-dimensional polymer is graphene, but its thermolytic synthesis precludes molecular design on demand. Here, we have rationally synthesized an ordered, non-equilibrium two-dimensional polymer far beyond molecular dimensions. The procedure includes the crystallization of a specifically designed photoreactive monomer into a layered structure, a photo-polymerization step within the crystal and a solvent-induced delamination step that isolates individual two-dimensional polymers as free-standing, monolayered molecular sheets.
Second invariant for two-dimensional classical super systems
Indian Academy of Sciences (India)
S C Mishra; Roshan Lal; Veena Mishra
2003-10-01
Construction of superpotentials for two-dimensional classical super systems (for ≥ 2) is carried out. Some interesting potentials have been studied in their super form and also their integrability.
Extreme paths in oriented two-dimensional percolation
Andjel, E. D.; Gray, L. F.
2016-01-01
International audience; A useful result about leftmost and rightmost paths in two dimensional bond percolation is proved. This result was introduced without proof in \\cite{G} in the context of the contact process in continuous time. As discussed here, it also holds for several related models, including the discrete time contact process and two dimensional site percolation. Among the consequences are a natural monotonicity in the probability of percolation between different sites and a somewha...
Two Dimensional Nucleation Process by Monte Carlo Simulation
T., Irisawa; K., Matsumoto; Y., Arima; T., Kan; Computer Center, Gakushuin University; Department of Physics, Gakushuin University
1997-01-01
Two dimensional nucleation process on substrate is investigated by Monte Carlo simulation, and the critical nucleus size and its waiting time are measured with a high accuracy. In order to measure the critical nucleus with a high accuracy, we calculate the attachment and the detachment rate to the nucleus directly, and define the critical nucleus size when both rate are equal. Using the kinematical nucleation theory by Nishioka, it is found that, our obtained kinematical two dimensional criti...
Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers
2016-06-15
polymers . 2. Introduction . Research objectives: This research aims to study the physical (van der Waals forces: crystal epitaxy and π-π...AFRL-AFOSR-JP-TR-2016-0071 Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers Cheolmin Park YONSEI UNIVERSITY...Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA2386-14-1-4054 5c. PROGRAM ELEMENT
Two-Dimensional Weak Pseudomanifolds on Eight Vertices
Indian Academy of Sciences (India)
Basudeb Datta; Nandini Nilakantan
2002-05-01
We explicitly determine all the two-dimensional weak pseudomanifolds on 8 vertices. We prove that there are (up to isomorphism) exactly 95 such weak pseudomanifolds, 44 of which are combinatorial 2-manifolds. These 95 weak pseudomanifolds triangulate 16 topological spaces. As a consequence, we prove that there are exactly three 8-vertex two-dimensional orientable pseudomanifolds which allow degree three maps to the 4-vertex 2-sphere.
Two-Dimensional Materials for Sensing: Graphene and Beyond
Directory of Open Access Journals (Sweden)
Seba Sara Varghese
2015-09-01
Full Text Available Two-dimensional materials have attracted great scientific attention due to their unusual and fascinating properties for use in electronics, spintronics, photovoltaics, medicine, composites, etc. Graphene, transition metal dichalcogenides such as MoS2, phosphorene, etc., which belong to the family of two-dimensional materials, have shown great promise for gas sensing applications due to their high surface-to-volume ratio, low noise and sensitivity of electronic properties to the changes in the surroundings. Two-dimensional nanostructured semiconducting metal oxide based gas sensors have also been recognized as successful gas detection devices. This review aims to provide the latest advancements in the field of gas sensors based on various two-dimensional materials with the main focus on sensor performance metrics such as sensitivity, specificity, detection limit, response time, and reversibility. Both experimental and theoretical studies on the gas sensing properties of graphene and other two-dimensional materials beyond graphene are also discussed. The article concludes with the current challenges and future prospects for two-dimensional materials in gas sensor applications.
Efficient processing of two-dimensional arrays with C or C++
Donato, David I.
2017-07-20
Because fast and efficient serial processing of raster-graphic images and other two-dimensional arrays is a requirement in land-change modeling and other applications, the effects of 10 factors on the runtimes for processing two-dimensional arrays with C and C++ are evaluated in a comparative factorial study. This study’s factors include the choice among three C or C++ source-code techniques for array processing; the choice of Microsoft Windows 7 or a Linux operating system; the choice of 4-byte or 8-byte array elements and indexes; and the choice of 32-bit or 64-bit memory addressing. This study demonstrates how programmer choices can reduce runtimes by 75 percent or more, even after compiler optimizations. Ten points of practical advice for faster processing of two-dimensional arrays are offered to C and C++ programmers. Further study and the development of a C and C++ software test suite are recommended.Key words: array processing, C, C++, compiler, computational speed, land-change modeling, raster-graphic image, two-dimensional array, software efficiency
Temperature dependence of universal fluctuations in the two-dimensional harmonic XY model.
Palma, G
2006-04-01
We compute exact analytical expressions for the skewness and kurtosis in the two-dimensional harmonic XY model. These quantities correspond to the third and fourth normalized moments of the probability density function (PDF) of the magnetization of the model. From their behavior, we conclude that they depend explicitly on the system temperature even in the thermodynamic limit, and hence the PDF itself must depend on it. Our results correct the hypothesis called universal fluctuations, they confirm and extend previous results which showed a T dependence of the PDF, including perturbative expansions within the XY model up to first order in temperature.
Fundamental and vortex solitons in a two-dimensional optical lattice
Yang, J; Yang, Jianke; Musslimani, Ziad
2003-01-01
Fundamental and vortex solitons in a two-dimensional optically induced waveguide array are reported. In the strong localization regime, the fundamental soliton is largely confined to one lattice site, while the vortex state comprises of four fundamental modes superimposed in a square configuration with a phase structure that is topologically equivalent to the conventional vortex. However, in the weak localization regime, both the fundamental and vortex solitons spread over many lattice sites. We further show that fundamental and vortex solitons are stable against small perturbations in the strong localization regime.
Ultrashort light bullets described by the two-dimensional sine-Gordon equation
Leblond, Hervé; 10.1103/PHYSREVA.81.063815
2011-01-01
By using a reductive perturbation technique applied to a two-level model, this study puts forward a generic two-dimensional sine-Gordon evolution equation governing the propagation of femtosecond spatiotemporal optical solitons in Kerr media beyond the slowly varying envelope approximation. Direct numerical simulations show that, in contrast to the long-wave approximation, no collapse occurs, and that robust (2+1)-dimensional ultrashort light bullets may form from adequately chosen few-cycle input spatiotemporal wave forms. In contrast to the case of quadratic nonlinearity, the light bullets oscillate in both space and time and are therefore not steady-state lumps.
Hall Conductivity in a Quasi-Two-Dimensional Disordered Electron System
Institute of Scientific and Technical Information of China (English)
YANG Yong-Hong; WANG Yong-Gang; LIU Mei
2002-01-01
By making use of the diagrammatic techniques in perturbation theory,we have investigated the Hall effect in a quasi-two-dimensional disordered electron system.In the weakly localized regime,the analytical expression for quantum correction to Hall conductivity has been obtained using the Kubo formalism and quasiclassical approximation.The relevant dimensional crossover behavior from three dimensions to two dimensions with decreasing the interlayer hopping energy is discussed.The quantum interference effect is shown to have a vanishing correction t,o the Hall coefficient.
Energy Technology Data Exchange (ETDEWEB)
Becar, Ramon [Universidad Catolica de Temuco, Departamento de Ciencias Matematicas y Fisicas, Temuco (Chile); Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Saavedra, Joel [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)
2015-02-01
We study massive charged fermionic perturbations in the background of a charged two-dimensional dilatonic black hole, and we solve the Dirac equation analytically. Then we compute the reflection and transmission coefficients and the absorption cross section for massive charged fermionic fields, and we show that the absorption cross section vanishes at the low- and high-frequency limits. However, there is a range of frequencies where the absorption cross section is not null. Furthermore, we study the effect of the mass and electric charge of the fermionic field over the absorption cross section. (orig.)
Selection rule for Dirac-like points in two-dimensional dielectric photonic crystals
Li, Yan
2013-01-01
We developed a selection rule for Dirac-like points in two-dimensional dielectric photonic crystals. The rule is derived from a perturbation theory and states that a non-zero, mode-coupling integral between the degenerate Bloch states guarantees a Dirac-like point, regardless of the type of the degeneracy. In fact, the selection rule can also be determined from the symmetry of the Bloch states even without computing the integral. Thus, the existence of Dirac-like points can be quickly and conclusively predicted for various photonic crystals independent of wave polarization, lattice structure, and composition. © 2013 Optical Society of America.
Reddy, T. S. R.; Srivastava, R.; Mehmed, Oral
2002-01-01
An aeroelastic analysis system for flutter and forced response analysis of turbomachines based on a two-dimensional linearized unsteady Euler solver has been developed. The ASTROP2 code, an aeroelastic stability analysis program for turbomachinery, was used as a basis for this development. The ASTROP2 code uses strip theory to couple a two dimensional aerodynamic model with a three dimensional structural model. The code was modified to include forced response capability. The formulation was also modified to include aeroelastic analysis with mistuning. A linearized unsteady Euler solver, LINFLX2D is added to model the unsteady aerodynamics in ASTROP2. By calculating the unsteady aerodynamic loads using LINFLX2D, it is possible to include the effects of transonic flow on flutter and forced response in the analysis. The stability is inferred from an eigenvalue analysis. The revised code, ASTROP2-LE for ASTROP2 code using Linearized Euler aerodynamics, is validated by comparing the predictions with those obtained using linear unsteady aerodynamic solutions.
Directory of Open Access Journals (Sweden)
Yong Cai
2015-01-01
Full Text Available Chemical fingerprinting is currently a widely used tool that enables rapid and accurate quality evaluation of Traditional Chinese Medicine (TCM. However, chemical fingerprints are not amenable to information storage, recognition, and retrieval, which limit their use in Chinese medicine traceability. In this study, samples of three kinds of Chinese medicines were randomly selected and chemical fingerprints were then constructed by using high performance liquid chromatography. Based on chemical data, the process of converting the TCM chemical fingerprint into two-dimensional code is presented; preprocess and filtering algorithm are also proposed aiming at standardizing the large amount of original raw data. In order to know which type of two-dimensional code (2D is suitable for storing data of chemical fingerprints, current popular types of 2D codes are analyzed and compared. Results show that QR Code is suitable for recording the TCM chemical fingerprint. The fingerprint information of TCM can be converted into data format that can be stored as 2D code for traceability and quality control.
Energy Technology Data Exchange (ETDEWEB)
Davidson, J.W.; Dudziak, D.J.; Pelloni, S.; Stepanek, J.
1988-01-01
In a recent common Los Alamos/PSI effort, a sensitivity and nuclear data uncertainty path for the modular code system AARE (Advanced Analysis for Reactor Engineering) was developed. This path includes the cross-section code TRAMIX, the one-dimensional finite difference S/sub N/-transport code ONEDANT, the two-dimensional finite element S/sub N/-transport code TRISM, and the one- and two-dimensional sensitivity and nuclear data uncertainty code SENSIBL. Within the framework of the present work a complete set of forward and adjoint two-dimensional TRISM calculations were performed both for the bare, as well as for the Pb- and Be-preceeded, LBM using MATXS8 libraries. Then a two-dimensional sensitivity and uncertainty analysis for all cases was performed. The goal of this analysis was the determination of the uncertainties of a calculated tritium production per source neutron from lithium along the central Li/sub 2/O rod in the LBM. Considered were the contributions from /sup 1/H, /sup 6/Li, /sup 7/Li, /sup 9/Be, /sup nat/C, /sup 14/N, /sup 16/O, /sup 23/Na, /sup 27/Al, /sup nat/Si, /sup nat/Cr, /sup nat/Fe, /sup nat/Ni, and /sup nat/Pb. 22 refs., 1 fig., 3 tabs.
Dynamic patterns in a two-dimensional neural field with refractoriness.
Qi, Yang; Gong, Pulin
2015-08-01
The formation of dynamic patterns such as localized propagating waves is a fascinating self-organizing phenomenon that happens in a wide range of spatially extended systems including neural systems, in which they might play important functional roles. Here we derive a type of two-dimensional neural-field model with refractoriness to study the formation mechanism of localized waves. After comparing this model with existing neural-field models, we show that it is able to generate a variety of localized patterns, including stationary bumps, localized waves rotating along a circular path, and localized waves with longer-range propagation. We construct explicit bump solutions for the two-dimensional neural field and conduct a linear stability analysis on how a stationary bump transitions to a propagating wave under different spatial eigenmode perturbations. The neural-field model is then partially solved in a comoving frame to obtain localized wave solutions, whose spatial profiles are in good agreement with those obtained from simulations. We demonstrate that when there are multiple such propagating waves, they exhibit rich propagation dynamics, including propagation along periodically oscillating and irregular trajectories; these propagation dynamics are quantitatively characterized. In addition, we show that these waves can have repulsive or merging collisions, depending on their collision angles and the refractoriness parameter. Due to its analytical tractability, the two-dimensional neural-field model provides a modeling framework for studying localized propagating waves and their interactions.
Sufficient condition for the existence of interface states in some two-dimensional photonic crystals
Huang, Xueqin; Xiao, Meng; Zhang, Zhao-Qing; Chan, C. T.
2014-08-01
There is no assurance that interface states can be found at the boundary separating two materials. While a strong perturbation typically favors wave localization, we show on the contrary that in some two-dimensional photonic crystals (PCs) possessing a Dirac-like cone at k = 0 derived from monopole and dipoles excitation, a small perturbation is sufficient to create interface states. The conical dispersion together with the flat band at the zone center generates the existence of gaps in the projected band structure and the existence of single mode interface states inside the projected band gaps stems from the geometric phases of the bulk bands. The underlying physics for the existence of an interface state is related to the sign change of the surface impedance in the gaps above and below the flat band. The established results are applicable for long wavelength regimes where there is only one propagating diffraction order for an interlayer scattering.
Indian Academy of Sciences (India)
ALY R SEADAWY
2017-09-01
Nonlinear two-dimensional Kadomtsev–Petviashvili (KP) equation governs the behaviour of nonlinear waves in dusty plasmas with variable dust charge and two temperature ions. By using the reductive perturbation method, the two-dimensional dust-acoustic solitary waves (DASWs) in unmagnetized cold plasma consisting of dust fluid, ions and electrons lead to a KP equation. We derived the solitary travelling wave solutions of the twodimensional nonlinear KP equation by implementing sech–tanh, sinh–cosh, extended direct algebraic and fraction direct algebraicmethods. We found the electrostatic field potential and electric field in the form travellingwave solutions for two-dimensional nonlinear KP equation. The solutions for the KP equation obtained by using these methods can be demonstrated precisely and efficiency. As an illustration, we used the readymade package of $\\it{Mathematica}$ program 10.1 to solve the original problem. These solutions are in good agreement with the analytical one.
Numerically exact correlations and sampling in the two-dimensional Ising spin glass.
Thomas, Creighton K; Middleton, A Alan
2013-04-01
A powerful existing technique for evaluating statistical mechanical quantities in two-dimensional Ising models is based on constructing a matrix representing the nearest-neighbor spin couplings and then evaluating the Pfaffian of the matrix. Utilizing this technique and other more recent developments in evaluating elements of inverse matrices and exact sampling, a method and computer code for studying two-dimensional Ising models is developed. The formulation of this method is convenient and fast for computing the partition function and spin correlations. It is also useful for exact sampling, where configurations are directly generated with probability given by the Boltzmann distribution. These methods apply to Ising model samples with arbitrary nearest-neighbor couplings and can also be applied to general dimer models. Example results of computations are described, including comparisons with analytic results for the ferromagnetic Ising model, and timing information is provided.
Two-Dimensional Rotating Stall Analysis in a Wide Vaneless Diffuser
Directory of Open Access Journals (Sweden)
2006-01-01
Full Text Available We report a numerical study on the vaneless diffuser core flow instability in centrifugal compressors. The analysis is performed for the purpose of better understanding of the rotating stall flow mechanism in radial vaneless diffusers. Since the analysis is restricted to the two-dimensional core flow, the effect of the wall boundary layers is neglected. A commercial code with the standard incompressible viscous flow solver is applied to model the vaneless diffuser core flow in the plane parallel to the diffuser walls. At the diffuser inlet, rotating jet-wake velocity pattern is prescribed and at the diffuser outlet constant static pressure is assumed. Under these circumstances, two-dimensional rotating flow instability similar to rotating stall is found to exist. Performed parameter analysis reveals that this instability is strongly influenced by the diffuser geometry and the inlet and outlet flow conditions.
Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.
Wang, Qing Hua; Kalantar-Zadeh, Kourosh; Kis, Andras; Coleman, Jonathan N; Strano, Michael S
2012-11-01
The remarkable properties of graphene have renewed interest in inorganic, two-dimensional materials with unique electronic and optical attributes. Transition metal dichalcogenides (TMDCs) are layered materials with strong in-plane bonding and weak out-of-plane interactions enabling exfoliation into two-dimensional layers of single unit cell thickness. Although TMDCs have been studied for decades, recent advances in nanoscale materials characterization and device fabrication have opened up new opportunities for two-dimensional layers of thin TMDCs in nanoelectronics and optoelectronics. TMDCs such as MoS(2), MoSe(2), WS(2) and WSe(2) have sizable bandgaps that change from indirect to direct in single layers, allowing applications such as transistors, photodetectors and electroluminescent devices. We review the historical development of TMDCs, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.
Hamiltonian formalism of two-dimensional Vlasov kinetic equation.
Pavlov, Maxim V
2014-12-08
In this paper, the two-dimensional Benney system describing long wave propagation of a finite depth fluid motion and the multi-dimensional Russo-Smereka kinetic equation describing a bubbly flow are considered. The Hamiltonian approach established by J. Gibbons for the one-dimensional Vlasov kinetic equation is extended to a multi-dimensional case. A local Hamiltonian structure associated with the hydrodynamic lattice of moments derived by D. J. Benney is constructed. A relationship between this hydrodynamic lattice of moments and the two-dimensional Vlasov kinetic equation is found. In the two-dimensional case, a Hamiltonian hydrodynamic lattice for the Russo-Smereka kinetic model is constructed. Simple hydrodynamic reductions are presented.
Control Operator for the Two-Dimensional Energized Wave Equation
Directory of Open Access Journals (Sweden)
Sunday Augustus REJU
2006-07-01
Full Text Available This paper studies the analytical model for the construction of the two-dimensional Energized wave equation. The control operator is given in term of space and time t independent variables. The integral quadratic objective cost functional is subject to the constraint of two-dimensional Energized diffusion, Heat and a source. The operator that shall be obtained extends the Conjugate Gradient method (ECGM as developed by Hestenes et al (1952, [1]. The new operator enables the computation of the penalty cost, optimal controls and state trajectories of the two-dimensional energized wave equation when apply to the Conjugate Gradient methods in (Waziri & Reju, LEJPT & LJS, Issues 9, 2006, [2-4] to appear in this series.
Two-Dimensional Electronic Spectroscopy Using Incoherent Light: Theoretical Analysis
Turner, Daniel B; Sutor, Erika J; Hendrickson, Rebecca A; Gealy, M W; Ulness, Darin J
2012-01-01
Electronic energy transfer in photosynthesis occurs over a range of time scales and under a variety of intermolecular coupling conditions. Recent work has shown that electronic coupling between chromophores can lead to coherent oscillations in two-dimensional electronic spectroscopy measurements of pigment-protein complexes measured with femtosecond laser pulses. A persistent issue in the field is to reconcile the results of measurements performed using femtosecond laser pulses with physiological illumination conditions. Noisy-light spectroscopy can begin to address this question. In this work we present the theoretical analysis of incoherent two-dimensional electronic spectroscopy, I(4) 2D ES. Simulations reveal diagonal peaks, cross peaks, and coherent oscillations similar to those observed in femtosecond two-dimensional electronic spectroscopy experiments. The results also expose fundamental differences between the femtosecond-pulse and noisy-light techniques; the differences lead to new challenges and opp...
A two-dimensional spin liquid in quantum kagome ice.
Carrasquilla, Juan; Hao, Zhihao; Melko, Roger G
2015-06-22
Actively sought since the turn of the century, two-dimensional quantum spin liquids (QSLs) are exotic phases of matter where magnetic moments remain disordered even at zero temperature. Despite ongoing searches, QSLs remain elusive, due to a lack of concrete knowledge of the microscopic mechanisms that inhibit magnetic order in materials. Here we study a model for a broad class of frustrated magnetic rare-earth pyrochlore materials called quantum spin ices. When subject to an external magnetic field along the [111] crystallographic direction, the resulting interactions contain a mix of geometric frustration and quantum fluctuations in decoupled two-dimensional kagome planes. Using quantum Monte Carlo simulations, we identify a set of interactions sufficient to promote a groundstate with no magnetic long-range order, and a gap to excitations, consistent with a Z2 spin liquid phase. This suggests an experimental procedure to search for two-dimensional QSLs within a class of pyrochlore quantum spin ice materials.
Two dimensional convolute integers for machine vision and image recognition
Edwards, Thomas R.
1988-01-01
Machine vision and image recognition require sophisticated image processing prior to the application of Artificial Intelligence. Two Dimensional Convolute Integer Technology is an innovative mathematical approach for addressing machine vision and image recognition. This new technology generates a family of digital operators for addressing optical images and related two dimensional data sets. The operators are regression generated, integer valued, zero phase shifting, convoluting, frequency sensitive, two dimensional low pass, high pass and band pass filters that are mathematically equivalent to surface fitted partial derivatives. These operators are applied non-recursively either as classical convolutions (replacement point values), interstitial point generators (bandwidth broadening or resolution enhancement), or as missing value calculators (compensation for dead array element values). These operators show frequency sensitive feature selection scale invariant properties. Such tasks as boundary/edge enhancement and noise or small size pixel disturbance removal can readily be accomplished. For feature selection tight band pass operators are essential. Results from test cases are given.
Optical modulators with two-dimensional layered materials
Sun, Zhipei; Wang, Feng
2016-01-01
Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that two-dimensional layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this review, we cover the state-of-the-art of optical modulators based on two-dimensional layered materials including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as two-dimensional heterostructures, plasmonic structures, and silicon/fibre integrated structures. We also take a look at future perspectives and discuss the potential of yet relatively unexplored mechanisms such as magneto-optic and acousto-optic modulation.
Two-dimensional superconductors with atomic-scale thickness
Uchihashi, Takashi
2017-01-01
Recent progress in two-dimensional superconductors with atomic-scale thickness is reviewed mainly from the experimental point of view. The superconducting systems treated here involve a variety of materials and forms: elemental metal ultrathin films and atomic layers on semiconductor surfaces; interfaces and superlattices of heterostructures made of cuprates, perovskite oxides, and rare-earth metal heavy-fermion compounds; interfaces of electric-double-layer transistors; graphene and atomic sheets of transition metal dichalcogenide; iron selenide and organic conductors on oxide and metal surfaces, respectively. Unique phenomena arising from the ultimate two dimensionality of the system and the physics behind them are discussed.
Singular analysis of two-dimensional bifurcation system
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Bifurcation properties of two-dimensional bifurcation system are studied in this paper.Universal unfolding and transition sets of the bifurcation equations are obtained.The whole parametric plane is divided into several different persistent regions according to the type of motion,and the different qualitative bifurcation diagrams in different persistent regions are given.The bifurcation properties of the two-dimensional bifurcation system are compared with its reduced one-dimensional system.It is found that the system which is reduced to one dimension has lost many bifurcation properties.
Critical Behaviour of a Two-Dimensional Random Antiferromagnet
DEFF Research Database (Denmark)
Als-Nielsen, Jens Aage; Birgeneau, R. J.; Guggenheim, H. J.
1976-01-01
A neutron scattering study of the order parameter, correlation length and staggered susceptibility of the two-dimensional random antiferromagnet Rb2Mn0.5Ni0.5F4 is reported. The system is found to exhibit a well-defined phase transition with critical exponents identical to those of the isomorphou...... pure materials K2NiF4 and K2MnF4. Thus, in these systems, which have the asymptotic critical behaviour of the two-dimensional Ising model, randomness has no measurable effect on the phase-transition behaviour....
Nonlinear excitations in two-dimensional molecular structures with impurities
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Rasmussen, Kim; Christiansen, Peter Leth
1995-01-01
We study the nonlinear dynamics of electronic excitations interacting with acoustic phonons in two-dimensional molecular structures with impurities. We show that the problem is reduced to the nonlinear Schrodinger equation with a varying coefficient. The latter represents the influence of the imp......We study the nonlinear dynamics of electronic excitations interacting with acoustic phonons in two-dimensional molecular structures with impurities. We show that the problem is reduced to the nonlinear Schrodinger equation with a varying coefficient. The latter represents the influence...... excitations. Analytical results are in good agreement with numerical simulations of the nonlinear Schrodinger equation....
Vortices in the Two-Dimensional Simple Exclusion Process
Bodineau, T.; Derrida, B.; Lebowitz, Joel L.
2008-06-01
We show that the fluctuations of the partial current in two dimensional diffusive systems are dominated by vortices leading to a different scaling from the one predicted by the hydrodynamic large deviation theory. This is supported by exact computations of the variance of partial current fluctuations for the symmetric simple exclusion process on general graphs. On a two-dimensional torus, our exact expressions are compared to the results of numerical simulations. They confirm the logarithmic dependence on the system size of the fluctuations of the partial flux. The impact of the vortices on the validity of the fluctuation relation for partial currents is also discussed in an Appendix.
Two-dimensional hazard estimation for longevity analysis
DEFF Research Database (Denmark)
Fledelius, Peter; Guillen, M.; Nielsen, J.P.
2004-01-01
the two-dimensional mortality surface. Furthermore we look at aggregated synthetic population metrics as 'population life expectancy' and 'population survival probability'. For Danish women these metrics indicate decreasing mortality with respect to chronological time. The metrics can not directly be used......We investigate developments in Danish mortality based on data from 1974-1998 working in a two-dimensional model with chronological time and age as the two dimensions. The analyses are done with non-parametric kernel hazard estimation techniques. The only assumption is that the mortality surface...... for analysis of economic implications arising from mortality changes....
Field analysis of two-dimensional focusing grating couplers
Borsboom, P.-P.; Frankena, H. J.
1995-05-01
A different technique was developed by which several two-dimensional dielectric optical gratings, consisting 100 or more corrugations, were treated in a numerical reliable approach. The numerical examples that were presented were restricted to gratings made up of sequences of waveguide sections symmetric about the x = 0 plane. The newly developed method was effectively used to investigate the field produced by a two-dimensional focusing grating coupler. Focal-region fields were determined for three symmetrical gratings with 19, 50, and 124 corrugations. For focusing grating coupler with limited length, high-frequency intensity variations were noted in the focal region.
Self-assembly of two-dimensional DNA crystals
Institute of Scientific and Technical Information of China (English)
SONG Cheng; CHEN Yaqing; WEI Shuai; YOU Xiaozeng; XIAO Shoujun
2004-01-01
Self-assembly of synthetic oligonucleotides into two-dimensional lattices presents a 'bottom-up' approach to the fabrication of devices on nanometer scale. We report the design and observation of two-dimensional crystalline forms of DNAs that are composed of twenty-one plane oligonucleotides and one phosphate-modified oligonucleotide. These synthetic sequences are designed to self-assemble into four double-crossover (DX) DNA tiles. The 'sticky ends' of these tiles that associate according to Watson-Crick's base pairing are programmed to build up specific periodic patterns upto tens of microns. The patterned crystals are visualized by the transmission electron microscopy.
Dynamics of vortex interactions in two-dimensional flows
DEFF Research Database (Denmark)
Juul Rasmussen, J.; Nielsen, A.H.; Naulin, V.
2002-01-01
a critical value, a(c). Using the Weiss-field, a(c) is estimated for vortex patches. Introducing an effective radius for vortices with distributed vorticity, we find that 3.3 a(c) ...The dynamics and interaction of like-signed vortex structures in two dimensional flows are investigated by means of direct numerical solutions of the two-dimensional Navier-Stokes equations. Two vortices with distributed vorticity merge when their distance relative to their radius, d/R-0l. is below...
Two-dimensional assignment with merged measurements using Langrangrian relaxation
Briers, Mark; Maskell, Simon; Philpott, Mark
2004-01-01
Closely spaced targets can result in merged measurements, which complicate data association. Such merged measurements violate any assumption that each measurement relates to a single target. As a result, it is not possible to use the auction algorithm in its simplest form (or other two-dimensional assignment algorithms) to solve the two-dimensional target-to-measurement assignment problem. We propose an approach that uses the auction algorithm together with Lagrangian relaxation to incorporate the additional constraints resulting from the presence of merged measurements. We conclude with some simulated results displaying the concepts introduced, and discuss the application of this research within a particle filter context.
Two-dimensional lattice Boltzmann model for magnetohydrodynamics.
Schaffenberger, Werner; Hanslmeier, Arnold
2002-10-01
We present a lattice Boltzmann model for the simulation of two-dimensional magnetohydro dynamic (MHD) flows. The model is an extension of a hydrodynamic lattice Boltzman model with 9 velocities on a square lattice resulting in a model with 17 velocities. Earlier lattice Boltzmann models for two-dimensional MHD used a bidirectional streaming rule. However, the use of such a bidirectional streaming rule is not necessary. In our model, the standard streaming rule is used, allowing smaller viscosities. To control the viscosity and the resistivity independently, a matrix collision operator is used. The model is then applied to the Hartmann flow, giving reasonable results.
Quasinormal frequencies of asymptotically flat two-dimensional black holes
Lopez-Ortega, A
2011-01-01
We discuss whether the minimally coupled massless Klein-Gordon and Dirac fields have well defined quasinormal modes in single horizon, asymptotically flat two-dimensional black holes. To get the result we solve the equations of motion in the massless limit and we also calculate the effective potentials of Schrodinger type equations. Furthermore we calculate exactly the quasinormal frequencies of the Dirac field propagating in the two-dimensional uncharged Witten black hole. We compare our results on its quasinormal frequencies with other already published.
Spin dynamics in a two-dimensional quantum gas
DEFF Research Database (Denmark)
Pedersen, Poul Lindholm; Gajdacz, Miroslav; Deuretzbacher, Frank
2014-01-01
We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions with superimp......We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions...
Institute of Scientific and Technical Information of China (English)
Xu Quan; Tian Qiang
2009-01-01
This paper discusses the two-dimensional discrete monatomic Fermi-Pasta-Ulam lattice, by using the method of multiple-scale and the quasi-discreteness approach. By taking into account the interaction between the atoms in the lattice and their nearest neighbours, it obtains some classes of two-dimensional local models as follows: two-dimensional bright and dark discrete soliton trains, two-dimensional bright and dark line discrete breathers, and two-dimensional bright and dark discrete breather.
Mapping two-dimensional polar active fluids to two-dimensional soap and one-dimensional sandblasting
Chen, Leiming; Lee, Chiu Fan; Toner, John
2016-07-01
Active fluids and growing interfaces are two well-studied but very different non-equilibrium systems. Each exhibits non-equilibrium behaviour distinct from that of their equilibrium counterparts. Here we demonstrate a surprising connection between these two: the ordered phase of incompressible polar active fluids in two spatial dimensions without momentum conservation, and growing one-dimensional interfaces (that is, the 1+1-dimensional Kardar-Parisi-Zhang equation), in fact belong to the same universality class. This universality class also includes two equilibrium systems: two-dimensional smectic liquid crystals, and a peculiar kind of constrained two-dimensional ferromagnet. We use these connections to show that two-dimensional incompressible flocks are robust against fluctuations, and exhibit universal long-ranged, anisotropic spatio-temporal correlations of those fluctuations. We also thereby determine the exact values of the anisotropy exponent ζ and the roughness exponents χx,y that characterize these correlations.
Wetting of two-dimensional physically patterned surfaces
Bell, Michael Scott
features. In this work, we relax these assumptions. We begin by investigating the role of hierarchical roughness (specifically dual-scale roughness) in affecting static contact angles by making no assumptions other than that the effect of gravity is negligible, though the surface features are allowed to be similar in size to the droplet. By investigating phase diagrams of contact angles as a function of surface feature parameters, we find that the nanoscale roughness in hierarchical roughness serves mainly to amplify the intrinsic contact angle of the macroscale roughness, thereby allowing for large contact angles on relatively low aspect ratio macroscale structures. Next, we lift the assumption of the negligible effect of gravity, and consider arbitrarily-sized droplets relative to the surface features, for which the effect of gravity is non-negligible. From this, we find that the effect of gravity is primarily to shift the boundary between the Cassie and Wenzel modes in the phase diagram. Other effects of gravity on contact angles occur mainly when the drops are similar in size to the surface features. Further, by comparing predictions of a circular cap model with a deformable cap model, we find that the gravitationally-induced deformations mainly affect the contact angle, with the equilibrium wetting configurations predicted by both models being otherwise quite similar. Both of these studies reinforce the idea that pinning effects become less important when the surface features become much smaller than the drop size. We next explore this regime, in which the Cassie and Wenzel models become valid, in more detail. Specifically, we use perturbation theory to derive a correction to the Wenzel equation to properly account for the volume of liquid stored in the grooves which was not considered in the original derivation. By considering both the two- and three-dimensional cases, we find an intuitive explanation for the two-dimensional correction which unfortunately breaks down
Waiting Time Dynamics in Two-Dimensional Infrared Spectroscopy
Jansen, Thomas L. C.; Knoester, Jasper
We review recent work on the waiting time dynamics of coherent two-dimensional infrared (2DIR) spectroscopy. This dynamics can reveal chemical and physical processes that take place on the femto- and picosecond time scale, which is faster than the time scale that may be probed by, for example,
The partition function of two-dimensional string theory
Dijkgraaf, Robbert; Moore, Gregory; Plesser, Ronen
1993-04-01
We derive a compact and explicit expression for the generating functional of all correlation functions of tachyon operators in two-dimensional string theory. This expression makes manifest relations of the c = 1 system to KP flow nd W 1 + ∞ constraints. Moreover we derive a Kontsevich-Penner integral representation of this generating functional.
The partition function of two-dimensional string theory
Energy Technology Data Exchange (ETDEWEB)
Dijkgraaf, R. (School of Natural Sciences, Inst. for Advanced Study, Princeton, NJ (United States) Dept. of Mathematics, Univ. Amsterdam (Netherlands)); Moore, G.; Plesser, R. (Dept. of Physics, Yale Univ., New Haven, CT (United States))
1993-04-12
We derive a compact and explicit expression for the generating functional of all correlation functions of tachyon operators in two-dimensional string theory. This expression makes manifest relations of the c=1 system to KP flow and W[sub 1+[infinity
Two-Dimensional Electronic Spectroscopy of a Model Dimer System
Directory of Open Access Journals (Sweden)
Prokhorenko V.I.
2013-03-01
Full Text Available Two-dimensional spectra of a dimer were measured to determine the timescale for electronic decoherence at room temperature. Anti-correlated beats in the crosspeaks were observed only during the period corresponding to the measured homogeneous lifetime.
Torque magnetometry studies of two-dimensional electron systems
Schaapman, Maaike Ruth
2004-01-01
This thesis describes a study of the magnetization two-dimensional electron gases (2DEGs). To detect the typically small magnetization, a sensitive magnetometer with optical angular detection was developed. The magnetometer uses a quadrant detector to measure the rotation of the sample. By mounting
Low-frequency scattering from two-dimensional perfect conductors
DEFF Research Database (Denmark)
Hansen, Thorkild; Yaghjian, A.D
1991-01-01
Exact expressions have been obtained for the leading terms in the low-frequency expansions of the far fields scattered from three different types of two-dimensional perfect conductors: a cylinder with finite cross section, a cylindrical bump on an infinite ground plane, and a cylindrical dent...
Two-Dimensional Mesoscale-Ordered Conducting Polymers
Liu, Shaohua; Zhang, Jian; Dong, Renhao; Gordiichuk, Pavlo; Zhang, Tao; Zhuang, Xiaodong; Mai, Yiyong; Liu, Feng; Herrmann, Andreas; Feng, Xinliang
2016-01-01
Despite the availability of numerous two-dimensional (2D) materials with structural ordering at the atomic or molecular level, direct construction of mesoscale-ordered superstructures within a 2D monolayer remains an enormous challenge. Here, we report the synergic manipulation of two types of assem
Piezoelectricity and Piezomagnetism: Duality in two-dimensional checkerboards
Fel, Leonid G.
2002-05-01
The duality approach in two-dimensional two-component regular checkerboards is extended to piezoelectricity and piezomagnetism. The relation between the effective piezoelectric and piezomagnetic moduli is found for a checkerboard with the p6'mm'-plane symmetry group (dichromatic triangle).
Operator splitting for two-dimensional incompressible fluid equations
Holden, Helge; Karper, Trygve K
2011-01-01
We analyze splitting algorithms for a class of two-dimensional fluid equations, which includes the incompressible Navier-Stokes equations and the surface quasi-geostrophic equation. Our main result is that the Godunov and Strang splitting methods converge with the expected rates provided the initial data are sufficiently regular.
Chaotic dynamics for two-dimensional tent maps
Pumariño, Antonio; Ángel Rodríguez, José; Carles Tatjer, Joan; Vigil, Enrique
2015-02-01
For a two-dimensional extension of the classical one-dimensional family of tent maps, we prove the existence of an open set of parameters for which the respective transformation presents a strange attractor with two positive Lyapounov exponents. Moreover, periodic orbits are dense on this attractor and the attractor supports a unique ergodic invariant probability measure.
Divorticity and dihelicity in two-dimensional hydrodynamics
DEFF Research Database (Denmark)
Shivamoggi, B.K.; van Heijst, G.J.F.; Juul Rasmussen, Jens
2010-01-01
A framework is developed based on the concepts of divorticity B (≡×ω, ω being the vorticity) and dihelicity g (≡vB) for discussing the theoretical structure underlying two-dimensional (2D) hydrodynamics. This formulation leads to the global and Lagrange invariants that could impose significant...
Spin-orbit torques in two-dimensional Rashba ferromagnets
Qaiumzadeh, A.; Duine, R. A.|info:eu-repo/dai/nl/304830127; Titov, M.
2015-01-01
Magnetization dynamics in single-domain ferromagnets can be triggered by a charge current if the spin-orbit coupling is sufficiently strong. We apply functional Keldysh theory to investigate spin-orbit torques in metallic two-dimensional Rashba ferromagnets in the presence of spin-dependent
Numerical blowup in two-dimensional Boussinesq equations
Yin, Zhaohua
2009-01-01
In this paper, we perform a three-stage numerical relay to investigate the finite time singularity in the two-dimensional Boussinesq approximation equations. The initial asymmetric condition is the middle-stage output of a $2048^2$ run, the highest resolution in our study is $40960^2$, and some signals of numerical blowup are observed.
Exact two-dimensional superconformal R symmetry and c extremization.
Benini, Francesco; Bobev, Nikolay
2013-02-08
We uncover a general principle dubbed c extremization, which determines the exact R symmetry of a two-dimensional unitary superconformal field theory with N=(0,2) supersymmetry. To illustrate its utility, we study superconformal theories obtained by twisted compactifications of four-dimensional N=4 super-Yang-Mills theory on Riemann surfaces and construct their gravity duals.
Zero sound in a two-dimensional dipolar Fermi gas
Lu, Z.K.; Matveenko, S.I.; Shlyapnikov, G.V.
2013-01-01
We study zero sound in a weakly interacting two-dimensional (2D) gas of single-component fermionic dipoles (polar molecules or atoms with a large magnetic moment) tilted with respect to the plane of their translational motion. It is shown that the propagation of zero sound is provided by both mean-f
Topology optimization of two-dimensional elastic wave barriers
DEFF Research Database (Denmark)
Van Hoorickx, C.; Sigmund, Ole; Schevenels, M.
2016-01-01
Topology optimization is a method that optimally distributes material in a given design domain. In this paper, topology optimization is used to design two-dimensional wave barriers embedded in an elastic halfspace. First, harmonic vibration sources are considered, and stiffened material is insert...
Thermodynamics of Two-Dimensional Black-Holes
Nappi, Chiara R.; Pasquinucci, Andrea
1992-01-01
We explore the thermodynamics of a general class of two dimensional dilatonic black-holes. A simple prescription is given that allows us to compute the mass, entropy and thermodynamic potentials, with results in agreement with those obtained by other methods, when available.
Influence of index contrast in two dimensional photonic crystal lasers
DEFF Research Database (Denmark)
Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Christiansen, Mads Brøkner;
2010-01-01
The influence of index contrast variations for obtaining single-mode operation and low threshold in dye doped polymer two dimensional photonic crystal (PhC) lasers is investigated. We consider lasers made from Pyrromethene 597 doped Ormocore imprinted with a rectangular lattice PhC having a cavit...
Magnetic order in two-dimensional nanoparticle assemblies
Georgescu, M
2008-01-01
This thesis involves a fundamental study of two-dimensional arrays of magnetic nanoparticles using non-contact Atomic Force Microscopy, Magnetic Force Microscopy, and Atomic Force Spectroscopy. The goal is to acquire a better understanding of the interactions between magnetic nanoparticles and the
Dynamical phase transitions in the two-dimensional ANNNI model
Energy Technology Data Exchange (ETDEWEB)
Barber, M.N.; Derrida, B.
1988-06-01
We study the phase diagram of the two-dimensional anisotropic next-nearest neighbor Ising (ANNNI) model by comparing the time evolution of two distinct spin configurations submitted to the same thermal noise. We clearly se several dynamical transitions between ferromagnetic, paramagnetic, antiphase, and floating phases. These dynamical transitions seem to occur rather close to the transition lines determined previously in the literature.
Two-dimensional static black holes with pointlike sources
Melis, M
2004-01-01
We study the static black hole solutions of generalized two-dimensional dilaton-gravity theories generated by pointlike mass sources, in the hypothesis that the matter is conformally coupled. We also discuss the motion of test particles. Due to conformal coupling, these follow the geodesics of a metric obtained by rescaling the canonical metric with the dilaton.
Magnetic order in two-dimensional nanoparticle assemblies
Georgescu, M
2008-01-01
This thesis involves a fundamental study of two-dimensional arrays of magnetic nanoparticles using non-contact Atomic Force Microscopy, Magnetic Force Microscopy, and Atomic Force Spectroscopy. The goal is to acquire a better understanding of the interactions between magnetic nanoparticles and the r
Two-Dimensional Chirality in Three-Dimensional Chemistry.
Wintner, Claude E.
1983-01-01
The concept of two-dimensional chirality is used to enhance students' understanding of three-dimensional stereochemistry. This chirality is used as a key to teaching/understanding such concepts as enaniotropism, diastereotopism, pseudoasymmetry, retention/inversion of configuration, and stereochemical results of addition to double bonds. (JN)
Field analysis of two-dimensional focusing grating
Borsboom, P.P.; Frankena, H.J.
1995-01-01
The method that we have developed [P-P. Borsboom, Ph.D. dissertation (Delft University of Technology, Delft, The Netherlands); P-P. Borsboom and H. J. Frankena, J. Opt. Soc. Am. A 12, 1134–1141 (1995)] is successfully applied to a two-dimensional focusing grating coupler. The field in the focal regi
Torque magnetometry studies of two-dimensional electron systems
Schaapman, Maaike Ruth
2004-01-01
This thesis describes a study of the magnetization two-dimensional electron gases (2DEGs). To detect the typically small magnetization, a sensitive magnetometer with optical angular detection was developed. The magnetometer uses a quadrant detector to measure the rotation of the sample. By mounting
Two-Dimensional Mesoscale-Ordered Conducting Polymers
Liu, Shaohua; Zhang, Jian; Dong, Renhao; Gordiichuk, Pavlo; Zhang, Tao; Zhuang, Xiaodong; Mai, Yiyong; Liu, Feng; Herrmann, Andreas; Feng, Xinliang
2016-01-01
Despite the availability of numerous two-dimensional (2D) materials with structural ordering at the atomic or molecular level, direct construction of mesoscale-ordered superstructures within a 2D monolayer remains an enormous challenge. Here, we report the synergic manipulation of two types of
Vibrations of Thin Piezoelectric Shallow Shells: Two-Dimensional Approximation
Indian Academy of Sciences (India)
N Sabu
2003-08-01
In this paper we consider the eigenvalue problem for piezoelectric shallow shells and we show that, as the thickness of the shell goes to zero, the eigensolutions of the three-dimensional piezoelectric shells converge to the eigensolutions of a two-dimensional eigenvalue problem.
Two-dimensional effects in nonlinear Kronig-Penney models
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Christiansen, Peter Leth; Rasmussen, Kim
1997-01-01
An analysis of two-dimensional (2D) effects in the nonlinear Kronig-Penney model is presented. We establish an effective one-dimensional description of the 2D effects, resulting in a set of pseudodifferential equations. The stationary states of the 2D system and their stability is studied...
Forensic potential of comprehensive two-dimensional gas chromatography
Sampat, A.; Lopatka, M.; Sjerps, M.; Vivo-Truyols, G.; Schoenmakers, P.; van Asten, A.
2016-01-01
In this study, the application of comprehensive two-dimensional (2D) gas chromatography (GC × GC) in forensic science is reviewed. The peer-reviewed publications on the forensic use of GC × GC and 2D gas chromatography with mass spectrometric detection (GC × GC-MS) have been studied in detail, not o
Easy interpretation of optical two-dimensional correlation spectra
Lazonder, K.; Pshenichnikov, M.S.; Wiersma, D.A.
2006-01-01
We demonstrate that the value of the underlying frequency-frequency correlation function can be retrieved from a two-dimensional optical correlation spectrum through a simple relationship. The proposed method yields both intuitive clues and a quantitative measure of the dynamics of the system. The t
Two Dimensional F(R) Horava-Lifshitz Gravity
Kluson, J
2016-01-01
We study two-dimensional F(R) Horava-Lifshitz gravity from the Hamiltonian point of view. We determine constraints structure with emphasis on the careful separation of the second class constraints and global first class constraints. We determine number of physical degrees of freedom and also discuss gauge fixing of the global first class constraints.
Localization of Tight Closure in Two-Dimensional Rings
Indian Academy of Sciences (India)
Kamran Divaani-Aazar; Massoud Tousi
2005-02-01
It is shown that tight closure commutes with localization in any two-dimensional ring of prime characteristic if either is a Nagata ring or possesses a weak test element. Moreover, it is proved that tight closure commutes with localization at height one prime ideals in any ring of prime characteristic.
Cryptanalysis of the Two-Dimensional Circulation Encryption Algorithm
Directory of Open Access Journals (Sweden)
Bart Preneel
2005-07-01
Full Text Available We analyze the security of the two-dimensional circulation encryption algorithm (TDCEA, recently published by Chen et al. in this journal. We show that there are several flaws in the algorithm and describe some attacks. We also address performance issues in current cryptographic designs.
New directions in science and technology: two-dimensional crystals
Energy Technology Data Exchange (ETDEWEB)
Neto, A H Castro [Graphene Research Centre, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Novoselov, K, E-mail: phycastr@nus.edu.sg, E-mail: konstantin.novoselov@manchester.ac.uk [School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom)
2011-08-15
Graphene is possibly one of the largest and fastest growing fields in condensed matter research. However, graphene is only one example in a large class of two-dimensional crystals with unusual properties. In this paper we briefly review the properties of graphene and look at the exciting possibilities that lie ahead.
Boundary-value problems for two-dimensional canonical systems
Hassi, Seppo; De Snoo, H; Winkler, Henrik
2000-01-01
The two-dimensional canonical system Jy' = -lHy where the nonnegative Hamiltonian matrix function H(x) is trace-normed on (0,∞) has been studied in a function-theoretic way by L. de Branges. We show that the Hamiltonian system induces a closed symmetric relation which can be reduced to a, not necess
On the continua in two-dimensional nonadiabatic magnetohydrodynamic spectra
De Ploey, A.; Van der Linden, R. A. M.; Belien, A. J. C.
2000-01-01
The equations for the continuous subspectra of the linear magnetohydrodynamic (MHD) normal modes spectrum of two-dimensional (2D) plasmas are derived in general curvilinear coordinates, taking nonadiabatic effects in the energy equation into account. Previously published derivations of continuous sp
Dislocation climb in two-dimensional discrete dislocation dynamics
Davoudi, K.M.; Nicola, L.; Vlassak, J.J.
2012-01-01
In this paper, dislocation climb is incorporated in a two-dimensional discrete dislocation dynamics model. Calculations are carried out for polycrystalline thin films, passivated on one or both surfaces. Climb allows dislocations to escape from dislocation pile-ups and reduces the strain-hardening r
SAR Processing Based On Two-Dimensional Transfer Function
Chang, Chi-Yung; Jin, Michael Y.; Curlander, John C.
1994-01-01
Exact transfer function, ETF, is two-dimensional transfer function that constitutes basis of improved frequency-domain-convolution algorithm for processing synthetic-aperture-radar, SAR data. ETF incorporates terms that account for Doppler effect of motion of radar relative to scanned ground area and for antenna squint angle. Algorithm based on ETF outperforms others.
Sound waves in two-dimensional ducts with sinusoidal walls
Nayfeh, A. H.
1974-01-01
The method of multiple scales is used to analyze the wave propagation in two-dimensional hard-walled ducts with sinusoidal walls. For traveling waves, resonance occurs whenever the wall wavenumber is equal to the difference of the wavenumbers of any two duct acoustic modes. The results show that neither of these resonating modes could occur without strongly generating the other.
Confined two-dimensional fermions at finite density
De Francia, M; Loewe, M; Santangelo, E M; De Francia, M; Falomir, H; Loewe, M; Santangelo, E M
1995-01-01
We introduce the chemical potential in a system of two-dimensional massless fermions, confined to a finite region, by imposing twisted boundary conditions in the Euclidean time direction. We explore in this simple model the application of functional techniques which could be used in more complicated situations.
Imperfect two-dimensional topological insulator field-effect transistors
Vandenberghe, William G.; Fischetti, Massimo V.
2017-01-01
To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose two-dimensional topological insulator field-effect transistors that switch based on the modulation of scattering. We model transistors made of two-dimensional topological insulator ribbons accounting for scattering with phonons and imperfections. In the on-state, the Fermi level lies in the bulk bandgap and the electrons travel ballistically through the topologically protected edge states even in the presence of imperfections. In the off-state the Fermi level moves into the bandgap and electrons suffer from severe back-scattering. An off-current more than two-orders below the on-current is demonstrated and a high on-current is maintained even in the presence of imperfections. At low drain-source bias, the output characteristics are like those of conventional field-effect transistors, at large drain-source bias negative differential resistance is revealed. Complementary n- and p-type devices can be made enabling high-performance and low-power electronic circuits using imperfect two-dimensional topological insulators. PMID:28106059
Miniature sensor for two-dimensional magnetic field distributions
Fluitman, J.H.J.; Krabbe, H.W.
1972-01-01
Describes a simple method of production of a sensor for two-dimensional magnetic field distributions. The sensor consists of a strip of Ni-Fe(81-19), of which the magnetoresistance is utilized. Typical dimensions of the strip, placed at the edge of a glass substrate, are: length 100 mu m, width 2 or
Forensic potential of comprehensive two-dimensional gas chromatography
Sampat, A.; Lopatka, M.; Sjerps, M.; Vivo-Truyols, G.; Schoenmakers, P.; van Asten, A.
2016-01-01
In this study, the application of comprehensive two-dimensional (2D) gas chromatography (GC × GC) in forensic science is reviewed. The peer-reviewed publications on the forensic use of GC × GC and 2D gas chromatography with mass spectrometric detection (GC × GC-MS) have been studied in detail, not o
Spontaneous emission in two-dimensional photonic crystal microcavities
DEFF Research Database (Denmark)
Søndergaard, Thomas
2000-01-01
The properties of the radiation field in a two-dimensional photonic crystal with and without a microcavity introduced are investigated through the concept of the position-dependent photon density of states. The position-dependent rate of spontaneous radiative decay for a two-level atom with random...
Linkage analysis by two-dimensional DNA typing
te Meerman, G J; Mullaart, E; van der Meulen, M A; den Daas, J H; Morolli, B; Uitterlinden, A G; Vijg, J
1993-01-01
In two-dimensional (2-D) DNA typing, genomic DNA fragments are separated, first according to size by electrophoresis in a neutral polyacrylamide gel and second according to sequence by denaturing gradient gel electrophoresis, followed by hybridization analysis using micro- and minisatellite core pro
Phase conjugated Andreev backscattering in two-dimensional ballistic cavities
Morpurgo, A.F.; Holl, S.; Wees, B.J.van; Klapwijk, T.M; Borghs, G.
1997-01-01
We have experimentally investigated transport in two-dimensional ballistic cavities connected to a point contact and to two superconducting electrodes with a tunable macroscopic phase difference. The point contact resistance oscillates as a function of the phase difference in a way which reflects
Two-dimensional manifold with point-like defects
Gani, Vakhid A; Rubin, Sergei G
2014-01-01
We study a class of two-dimensional extra spaces isomorphic to the $S^2$ sphere in the framework of the multidimensional gravitation. We show that there exists a family of stationary metrics that depend on the initial (boundary) conditions. All these geometries have a singular point. We also discuss the possibility for these deformed extra spaces to be considered as dark matter candidates.
Instability of two-dimensional heterotic stringy black holes
Azreg-Ainou, M
1999-01-01
We solve the eigenvalue problem of general relativity for the case of charged black holes in two-dimensional heterotic string theory, derived by McGuigan et al. For the case of $m^{2}>q^{2}$, we find a physically acceptable time-dependent growing mode; thus the black hole is unstable. The extremal case $m^{2}=q^{2}$ is stable.
Institute of Scientific and Technical Information of China (English)
XIONG Lei; LI haijiao; ZHANG Lewen
2008-01-01
The fourth-order B spline wavelet scaling functions are used to solve the two-dimensional unsteady diffusion equation. The calculations from a case history indicate that the method provides high accuracy and the computational efficiency is enhanced due to the small matrix derived from this method.The respective features of 3-spline wavelet scaling functions, 4-spline wavelet scaling functions and quasi-wavelet used to solve the two-dimensional unsteady diffusion equation are compared. The proposed method has potential applications in many fields including marine science.
Directory of Open Access Journals (Sweden)
shadan sadigh behzadi
2012-03-01
Full Text Available In this present paper, we solve a two-dimensional nonlinear Volterra-Fredholm integro-differential equation by using the following powerful, efficient but simple methods: (i Modified Adomian decomposition method (MADM, (ii Variational iteration method (VIM, (iii Homotopy analysis method (HAM and (iv Modified homotopy perturbation method (MHPM. The uniqueness of the solution and the convergence of the proposed methods are proved in detail. Numerical examples are studied to demonstrate the accuracy of the presented methods.
Energy Technology Data Exchange (ETDEWEB)
Goldberg, L.F. [Univ. of Minnesota, Minneapolis, MN (United States)
1990-08-01
The activities described in this report do not constitute a continuum but rather a series of linked smaller investigations in the general area of one- and two-dimensional Stirling machine simulation. The initial impetus for these investigations was the development and construction of the Mechanical Engineering Test Rig (METR) under a grant awarded by NASA to Dr. Terry Simon at the Department of Mechanical Engineering, University of Minnesota. The purpose of the METR is to provide experimental data on oscillating turbulent flows in Stirling machine working fluid flow path components (heater, cooler, regenerator, etc.) with particular emphasis on laminar/turbulent flow transitions. Hence, the initial goals for the grant awarded by NASA were, broadly, to provide computer simulation backup for the design of the METR and to analyze the results produced. This was envisaged in two phases: First, to apply an existing one-dimensional Stirling machine simulation code to the METR and second, to adapt a two-dimensional fluid mechanics code which had been developed for simulating high Rayleigh number buoyant cavity flows to the METR. The key aspect of this latter component was the development of an appropriate turbulence model suitable for generalized application to Stirling simulation. A final-step was then to apply the two-dimensional code to an existing Stirling machine for which adequate experimental data exist. The work described herein was carried out over a period of three years on a part-time basis. Forty percent of the first year`s funding was provided as a match to the NASA funds by the Underground Space Center, University of Minnesota, which also made its computing facilities available to the project at no charge.
Narin, B; Ozyörük, Y; Ulas, A
2014-05-30
This paper describes a two-dimensional code developed for analyzing two-phase deflagration-to-detonation transition (DDT) phenomenon in granular, energetic, solid, explosive ingredients. The two-dimensional model is constructed in full two-phase, and based on a highly coupled system of partial differential equations involving basic flow conservation equations and some constitutive relations borrowed from some one-dimensional studies that appeared in open literature. The whole system is solved using an optimized high-order accurate, explicit, central-difference scheme with selective-filtering/shock capturing (SF-SC) technique, to augment central-diffencing and prevent excessive dispersion. The sources of the equations describing particle-gas interactions in terms of momentum and energy transfers make the equation system quite stiff, and hence its explicit integration difficult. To ease the difficulties, a time-split approach is used allowing higher time steps. In the paper, the physical model for the sources of the equation system is given for a typical explosive, and several numerical calculations are carried out to assess the developed code. Microscale intergranular and/or intragranular effects including pore collapse, sublimation, pyrolysis, etc. are not taken into account for ignition and growth, and a basic temperature switch is applied in calculations to control ignition in the explosive domain. Results for one-dimensional DDT phenomenon are in good agreement with experimental and computational results available in literature. A typical shaped-charge wave-shaper case study is also performed to test the two-dimensional features of the code and it is observed that results are in good agreement with those of commercial software. Copyright © 2014 Elsevier B.V. All rights reserved.
Liu, Jen-Chang; Shieh, Hsiang-An
2011-01-01
Traditional two-dimensional (2-D) barcodes, such as the QR code and PDF417, do not carry visual information. This work proposes a visually meaningful 2-D barcode (or 2-D image code) that carries not only hidden information, but also visual information. Watermarking is employed to hide information in a meaningful cover image to produce the 2-D image code. The 2-D image code can be printed or displayed and then captured using a camera-equipped mobile device. The hidden information is extracted for innovative applications. To resist distortions in the print-and-photo process, a perceptual shaping algorithm, based on Watson's DCT-based perceptual model, is proposed for use in the data hiding procedure. The detection performance that can be achieved using two classes of position-detection patterns is evaluated, and the best pattern is then used as a part of the 2-D image code. A web service is provided for generating the 2-D image codes and a Java-based decoder is developed for mobile phones. The results of practical experiments reveal the applicability, robustness, and high capacity of the proposed 2-D image code.
A MATLAB package for the EIDORS project to reconstruct two-dimensional EIT images.
Vauhkonen, M; Lionheart, W R; Heikkinen, L M; Vauhkonen, P J; Kaipio, J P
2001-02-01
The EIDORS (electrical impedance and diffuse optical reconstruction software) project aims to produce a software system for reconstructing images from electrical or diffuse optical data. MATLAB is a software that is used in the EIDORS project for rapid prototyping, graphical user interface construction and image display. We have written a MATLAB package (http://venda.uku.fi/ vauhkon/) which can be used for two-dimensional mesh generation, solving the forward problem and reconstructing and displaying the reconstructed images (resistivity or admittivity). In this paper we briefly describe the mathematical theory on which the codes are based on and also give some examples of the capabilities of the package.
Quasiparticle GW calculations for solids, molecules, and two-dimensional materials
DEFF Research Database (Denmark)
Hüser, Falco; Olsen, Thomas; Thygesen, Kristian Sommer
2013-01-01
We present a plane-wave implementation of the GW approximation within the projector augmented wave method code GPAW. The computed band gaps of ten bulk semiconductors and insulators deviate on average by 0.2eV (~5%) from the experimental values, the only exception being ZnO where the calculated...... band gap is around 1eV too low. Similar relative deviations are found for the ionization potentials of a test set of 32 small molecules. The importance of substrate screening for a correct description of quasiparticle energies and Fermi velocities in supported two-dimensional (2D) materials...
Zhao, Qiang; Dong, Zhiwei
2016-11-01
We have developed two-dimensional Arbitrary Lagrangian Eulerian (ALE) code which is used to study the physical processes, the plasma absorption, the crater profile, and the temperature distribution on metallic target and below the surface. The ALE method overcomes problems with Lagrangian moving mesh distortion by mesh smoothing and conservative quantities remapping from Lagrangian mesh to smoothed one. The results of numerical simulation of pulsed laser ablation are presented. The study presents particular interest for the analysis of experimental results obtained during pulsed laser ablation.
Stress Wave Propagation in Two-dimensional Buckyball Lattice
Xu, Jun; Zheng, Bowen
2016-11-01
Orderly arrayed granular crystals exhibit extraordinary capability to tune stress wave propagation. Granular system of higher dimension renders many more stress wave patterns, showing its great potential for physical and engineering applications. At nanoscale, one-dimensionally arranged buckyball (C60) system has shown the ability to support solitary wave. In this paper, stress wave behaviors of two-dimensional buckyball (C60) lattice are investigated based on square close packing and hexagonal close packing. We show that the square close packed system supports highly directional Nesterenko solitary waves along initially excited chains and hexagonal close packed system tends to distribute the impulse and dissipates impact exponentially. Results of numerical calculations based on a two-dimensional nonlinear spring model are in a good agreement with the results of molecular dynamics simulations. This work enhances the understanding of wave properties and allows manipulations of nanoscale lattice and novel design of shock mitigation and nanoscale energy harvesting devices.
The separation of whale myoglobins with two-dimensional electrophoresis.
Spicer, G S
1988-10-01
Five myoglobins (sperm whale, Sei whale, Hubbs' beaked whale, pilot whale, and Amazon River dolphin) were examined using two-dimensional electrophoresis. Previous reports indicated that none of these proteins could be separated by using denaturing (in the presence of 8-9 M urea) isoelectric focusing. This result is confirmed in the present study. However, all the proteins could be separated by using denaturing nonequilibrium pH-gradient electrophoresis in the first dimension. Additionally, all the myoglobins have characteristic mobilities in the second dimension (sodium dodecyl sulfate), but these mobilities do not correspond to the molecular weights of the proteins. We conclude that two-dimensional electrophoresis can be more sensitive to differences in primary protein structure than previous studies indicate and that the assessment seems to be incorrect that this technique can separate only proteins that have a unit charge difference.
Entanglement Entropy in Two-Dimensional String Theory.
Hartnoll, Sean A; Mazenc, Edward A
2015-09-18
To understand an emergent spacetime is to understand the emergence of locality. Entanglement entropy is a powerful diagnostic of locality, because locality leads to a large amount of short distance entanglement. Two-dimensional string theory is among the very simplest instances of an emergent spatial dimension. We compute the entanglement entropy in the large-N matrix quantum mechanics dual to two-dimensional string theory in the semiclassical limit of weak string coupling. We isolate a logarithmically large, but finite, contribution that corresponds to the short distance entanglement of the tachyon field in the emergent spacetime. From the spacetime point of view, the entanglement is regulated by a nonperturbative "graininess" of space.
Topological defect motifs in two-dimensional Coulomb clusters
Radzvilavičius, A; 10.1088/0953-8984/23/38/385301
2012-01-01
The most energetically favourable arrangement of low-density electrons in an infinite two-dimensional plane is the ordered triangular Wigner lattice. However, in most instances of contemporary interest one deals instead with finite clusters of strongly interacting particles localized in potential traps, for example, in complex plasmas. In the current contribution we study distribution of topological defects in two-dimensional Coulomb clusters with parabolic lateral confinement. The minima hopping algorithm based on molecular dynamics is used to efficiently locate the ground- and low-energy metastable states, and their structure is analyzed by means of the Delaunay triangulation. The size, structure and distribution of geometry-induced lattice imperfections strongly depends on the system size and the energetic state. Besides isolated disclinations and dislocations, classification of defect motifs includes defect compounds --- grain boundaries, rosette defects, vacancies and interstitial particles. Proliferatio...
The Persistence Problem in Two-Dimensional Fluid Turbulence
Perlekar, Prasad; Mitra, Dhrubaditya; Pandit, Rahul
2010-01-01
We present a natural framework for studying the persistence problem in two-dimensional fluid turbulence by using the Okubo-Weiss parameter {\\Lambda} to distinguish between vortical and extensional regions. We then use a direct numerical simulation (DNS) of the two-dimensional, incompressible Navier-Stokes equation with Ekman friction to study probability distribution functions (PDFs) of the persistence times of vortical and extensional regions by employing both Eulerian and Lagrangian measurements. We find that, in the Eulerian case, the persistence-time PDFs have exponential tails; by contrast, this PDF for Lagrangian particles, in vortical regions, has a power-law tail with a universal exponent {\\theta} = 3.1 \\pm 0.2.
On Dirichlet eigenvectors for neutral two-dimensional Markov chains
Champagnat, Nicolas; Miclo, Laurent
2012-01-01
We consider a general class of discrete, two-dimensional Markov chains modeling the dynamics of a population with two types, without mutation or immigration, and neutral in the sense that type has no influence on each individual's birth or death parameters. We prove that all the eigenvectors of the corresponding transition matrix or infinitesimal generator \\Pi\\ can be expressed as the product of "universal" polynomials of two variables, depending on each type's size but not on the specific transitions of the dynamics, and functions depending only on the total population size. These eigenvectors appear to be Dirichlet eigenvectors for \\Pi\\ on the complement of triangular subdomains, and as a consequence the corresponding eigenvalues are ordered in a specific way. As an application, we study the quasistationary behavior of finite, nearly neutral, two-dimensional Markov chains, absorbed in the sense that 0 is an absorbing state for each component of the process.
Statistical mechanics of two-dimensional and geophysical flows
Bouchet, Freddy
2011-01-01
The theoretical study of the self-organization of two-dimensional and geophysical turbulent flows is addressed based on statistical mechanics methods. This review is a self-contained presentation of classical and recent works on this subject; from the statistical mechanics basis of the theory up to applications to Jupiter's troposphere and ocean vortices and jets. Emphasize has been placed on examples with available analytical treatment in order to favor better understanding of the physics and dynamics. The equilibrium microcanonical measure is built from the Liouville theorem. On this theoretical basis, we predict the output of the long time evolution of complex turbulent flows as statistical equilibria. This is applied to make quantitative models of two-dimensional turbulence, the Great Red Spot and other Jovian vortices, ocean jets like the Gulf-Stream, and ocean vortices. We also present recent results for non-equilibrium situations, for the studies of either the relaxation towards equilibrium or non-equi...
Two-dimensional hazard estimation for longevity analysis
DEFF Research Database (Denmark)
Fledelius, Peter; Guillen, M.; Nielsen, J.P.
2004-01-01
We investigate developments in Danish mortality based on data from 1974-1998 working in a two-dimensional model with chronological time and age as the two dimensions. The analyses are done with non-parametric kernel hazard estimation techniques. The only assumption is that the mortality surface...... the two-dimensional mortality surface. Furthermore we look at aggregated synthetic population metrics as 'population life expectancy' and 'population survival probability'. For Danish women these metrics indicate decreasing mortality with respect to chronological time. The metrics can not directly be used...... for prediction purposes. However, we suggest that life insurance companies use the estimation technique and the cross-validation for bandwidth selection when analyzing their portfolio mortality. The non-parametric approach may give valuable information prior to developing more sophisticated prediction models...
Analysis of one dimensional and two dimensional fuzzy controllers
Institute of Scientific and Technical Information of China (English)
Ban Xiaojun; Gao Xiaozhi; Huang Xianlin; Wu Tianbao
2006-01-01
The analytical structures and the corresponding mathematical properties of the one dimensional and two dimensional fuzzy controllers are first investigated in detail.The nature of these two kinds of fuzzy controllers is next probed from the perspective of control engineering. For the one dimensional fuzzy controller, it is concluded that this controller is a combination of a saturation element and a nonlinear proportional controller, and the system that employs the one dimensional fuzzy controller is the combination of an open-loop control system and a closedloop control system. For the latter case, it is concluded that it is a hybrid controller, which comprises the saturation part, zero-output part, nonlinear derivative part, nonlinear proportional part, as well as nonlinear proportional-derivative part, and the two dimensional fuzzy controller-based control system is a loop-varying system with varying number of control loops.
Extension of modified power method to two-dimensional problems
Zhang, Peng; Lee, Hyunsuk; Lee, Deokjung
2016-09-01
In this study, the generalized modified power method was extended to two-dimensional problems. A direct application of the method to two-dimensional problems was shown to be unstable when the number of requested eigenmodes is larger than a certain problem dependent number. The root cause of this instability has been identified as the degeneracy of the transfer matrix. In order to resolve this instability, the number of sub-regions for the transfer matrix was increased to be larger than the number of requested eigenmodes; and a new transfer matrix was introduced accordingly which can be calculated by the least square method. The stability of the new method has been successfully demonstrated with a neutron diffusion eigenvalue problem and the 2D C5G7 benchmark problem.
Two Dimensional Lattice Boltzmann Method for Cavity Flow Simulation
Directory of Open Access Journals (Sweden)
Panjit MUSIK
2004-01-01
Full Text Available This paper presents a simulation of incompressible viscous flow within a two-dimensional square cavity. The objective is to develop a method originated from Lattice Gas (cellular Automata (LGA, which utilises discrete lattice as well as discrete time and can be parallelised easily. Lattice Boltzmann Method (LBM, known as discrete Lattice kinetics which provide an alternative for solving the Navier–Stokes equations and are generally used for fluid simulation, is chosen for the study. A specific two-dimensional nine-velocity square Lattice model (D2Q9 Model is used in the simulation with the velocity at the top of the cavity kept fixed. LBM is an efficient method for reproducing the dynamics of cavity flow and the results which are comparable to those of previous work.
Transport behavior of water molecules through two-dimensional nanopores
Energy Technology Data Exchange (ETDEWEB)
Zhu, Chongqin; Li, Hui; Meng, Sheng, E-mail: smeng@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)
2014-11-14
Water transport through a two-dimensional nanoporous membrane has attracted increasing attention in recent years thanks to great demands in water purification and desalination applications. However, few studies have been reported on the microscopic mechanisms of water transport through structured nanopores, especially at the atomistic scale. Here we investigate the microstructure of water flow through two-dimensional model graphene membrane containing a variety of nanopores of different size by using molecular dynamics simulations. Our results clearly indicate that the continuum flow transits to discrete molecular flow patterns with decreasing pore sizes. While for pores with a diameter ≥15 Å water flux exhibits a linear dependence on the pore area, a nonlinear relationship between water flux and pore area has been identified for smaller pores. We attribute this deviation from linear behavior to the presence of discrete water flow, which is strongly influenced by the water-membrane interaction and hydrogen bonding between water molecules.
Transport behavior of water molecules through two-dimensional nanopores
Zhu, Chongqin; Li, Hui; Meng, Sheng
2014-11-01
Water transport through a two-dimensional nanoporous membrane has attracted increasing attention in recent years thanks to great demands in water purification and desalination applications. However, few studies have been reported on the microscopic mechanisms of water transport through structured nanopores, especially at the atomistic scale. Here we investigate the microstructure of water flow through two-dimensional model graphene membrane containing a variety of nanopores of different size by using molecular dynamics simulations. Our results clearly indicate that the continuum flow transits to discrete molecular flow patterns with decreasing pore sizes. While for pores with a diameter ≥15 Å water flux exhibits a linear dependence on the pore area, a nonlinear relationship between water flux and pore area has been identified for smaller pores. We attribute this deviation from linear behavior to the presence of discrete water flow, which is strongly influenced by the water-membrane interaction and hydrogen bonding between water molecules.
Thermodynamics of two-dimensional Yukawa systems across coupling regimes
Kryuchkov, Nikita P.; Khrapak, Sergey A.; Yurchenko, Stanislav O.
2017-04-01
Thermodynamics of two-dimensional Yukawa (screened Coulomb or Debye-Hückel) systems is studied systematically using molecular dynamics (MD) simulations. Simulations cover very broad parameter range spanning from weakly coupled gaseous states to strongly coupled fluid and crystalline states. Important thermodynamic quantities, such as internal energy and pressure, are obtained and accurate physically motivated fits are proposed. This allows us to put forward simple practical expressions to describe thermodynamic properties of two-dimensional Yukawa systems. For crystals, in addition to numerical simulations, the recently developed shortest-graph interpolation method is applied to describe pair correlations and hence thermodynamic properties. It is shown that the finite-temperature effects can be accounted for by using simple correction of peaks in the pair correlation function. The corresponding correction coefficients are evaluated using MD simulation. The relevance of the obtained results in the context of colloidal systems, complex (dusty) plasmas, and ions absorbed to interfaces in electrolytes is pointed out.
Topological states in two-dimensional hexagon lattice bilayers
Zhang, Ming-Ming; Xu, Lei; Zhang, Jun
2016-10-01
We investigate the topological states of the two-dimensional hexagon lattice bilayer. The system exhibits a quantum valley Hall (QVH) state when the interlayer interaction t⊥ is smaller than the nearest neighbor hopping energy t, and then translates to a trivial band insulator state when t⊥ / t > 1. Interestingly, the system is found to be a single-edge QVH state with t⊥ / t = 1. The topological phase transition also can be presented via changing bias voltage and sublattice potential in the system. The QVH states have different edge modes carrying valley current but no net charge current. The bias voltage and external electric field can be tuned easily in experiments, so the present results will provide potential application in valleytronics based on the two-dimensional hexagon lattice.
CORPORATE VALUATION USING TWO-DIMENSIONAL MONTE CARLO SIMULATION
Directory of Open Access Journals (Sweden)
Toth Reka
2010-12-01
Full Text Available In this paper, we have presented a corporate valuation model. The model combine several valuation methods in order to get more accurate results. To determine the corporate asset value we have used the Gordon-like two-stage asset valuation model based on the calculation of the free cash flow to the firm. We have used the free cash flow to the firm to determine the corporate market value, which was calculated with use of the Black-Scholes option pricing model in frame of the two-dimensional Monte Carlo simulation method. The combined model and the use of the two-dimensional simulation model provides a better opportunity for the corporate value estimation.
Two-dimensional magnetostriction under vector magnetic characteristic
Wakabayashi, D.; Enokizono, M.
2015-05-01
This paper presents two-dimensional magnetostriction of electrical steel sheet under vector magnetic characteristic. In conventional measurement method using Single Sheet Tester, the magnetic flux density, the magnetic field strength, and the magnetostriction have been measured in one direction. However, an angle between the magnetic flux density vector and the magnetic field strength vector exists because the magnetic property is vector quantity. An angle between the magnetic flux density vector and the direction of maximum magnetostriction also exists. We developed a new measurement method, which enables measurement of these angles. The vector magnetic characteristic and the two-dimensional magnetostriction have been measured using the new measurement method. The BH and Bλ curves considering the angles are shown in this paper. The analyzed results considering the angles are also made clear.
Phase separation under two-dimensional Poiseuille flow.
Kiwata, H
2001-05-01
The spinodal decomposition of a two-dimensional binary fluid under Poiseuille flow is studied by numerical simulation. We investigated time dependence of domain sizes in directions parallel and perpendicular to the flow. In an effective region of the flow, the power-law growth of a characteristic length in the direction parallel to the flow changes from the diffusive regime with the growth exponent alpha=1/3 to a new regime. The scaling invariance of the growth in the perpendicular direction is destroyed after the diffusive regime. A recurrent prevalence of thick and thin domains which determines log-time periodic oscillations has not been observed in our model. The growth exponents in the infinite system under two-dimensional Poiseuille flow are obtained by the renormalization group.
Enstrophy inertial range dynamics in generalized two-dimensional turbulence
Iwayama, Takahiro; Watanabe, Takeshi
2016-07-01
We show that the transition to a k-1 spectrum in the enstrophy inertial range of generalized two-dimensional turbulence can be derived analytically using the eddy damped quasinormal Markovianized (EDQNM) closure. The governing equation for the generalized two-dimensional fluid system includes a nonlinear term with a real parameter α . This parameter controls the relationship between the stream function and generalized vorticity and the nonlocality of the dynamics. An asymptotic analysis accounting for the overwhelming dominance of nonlocal triads allows the k-1 spectrum to be derived based upon a scaling analysis. We thereby provide a detailed analytical explanation for the scaling transition that occurs in the enstrophy inertial range at α =2 in terms of the spectral dynamics of the EDQNM closure, which extends and enhances the usual phenomenological explanations.
Folding two dimensional crystals by swift heavy ion irradiation
Energy Technology Data Exchange (ETDEWEB)
Ochedowski, Oliver; Bukowska, Hanna [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Freire Soler, Victor M. [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Departament de Fisica Aplicada i Optica, Universitat de Barcelona, E08028 Barcelona (Spain); Brökers, Lara [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Ban-d' Etat, Brigitte; Lebius, Henning [CIMAP (CEA-CNRS-ENSICAEN-UCBN), 14070 Caen Cedex 5 (France); Schleberger, Marika, E-mail: marika.schleberger@uni-due.de [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany)
2014-12-01
Ion irradiation of graphene, the showcase model of two dimensional crystals, has been successfully applied to induce various modifications in the graphene crystal. One of these modifications is the formation of origami like foldings in graphene which are created by swift heavy ion irradiation under glancing incidence angle. These foldings can be applied to locally alter the physical properties of graphene like mechanical strength or chemical reactivity. In this work we show that the formation of foldings in two dimensional crystals is not restricted to graphene but can be applied for other materials like MoS{sub 2} and hexagonal BN as well. Further we show that chemical vapour deposited graphene forms foldings after swift heavy ion irradiation while chemical vapour deposited MoS{sub 2} does not.
Explorative data analysis of two-dimensional electrophoresis gels
DEFF Research Database (Denmark)
Schultz, J.; Gottlieb, D.M.; Petersen, Marianne Kjerstine
2004-01-01
Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening...... of gels is presented. First, an approach is demonstrated in which no prior knowledge of the separated proteins is used. Alignment of the gels followed by a simple transformation of data makes it possible to analyze the gels in an automated explorative manner by principal component analysis, to determine...... if the gels should be further analyzed. A more detailed approach is done by analyzing spot volume lists by principal components analysis and partial least square regression. The use of spot volume data offers a mean to investigate the spot pattern and link the classified protein patterns to distinct spots...
Two-dimensional model of elastically coupled molecular motors
Institute of Scientific and Technical Information of China (English)
Zhang Hong-Wei; Wen Shu-Tang; Chen Gai-Rong; Li Yu-Xiao; Cao Zhong-Xing; Li Wei
2012-01-01
A flashing ratchet model of a two-headed molecular motor in a two-dimensional potential is proposed to simulate the hand-over-hand motion of kinesins.Extensive Langevin simulations of the model are performed.We discuss the dependences of motion and efficiency on the model parameters,including the external force and the temperature.A good qualitative agreement with the expected behavior is observed.
Conductivity of a two-dimensional guiding center plasma.
Montgomery, D.; Tappert, F.
1972-01-01
The Kubo method is used to calculate the electrical conductivity of a two-dimensional, strongly magnetized plasma. The particles interact through (logarithmic) electrostatic potentials and move with their guiding center drift velocities (Taylor-McNamara model). The thermal equilibrium dc conductivity can be evaluated analytically, but the ac conductivity involves numerical solution of a differential equation. Both conductivities fall off as the inverse first power of the magnetic field strength.
Minor magnetization loops in two-dimensional dipolar Ising model
Energy Technology Data Exchange (ETDEWEB)
Sarjala, M. [Aalto University, Department of Applied Physics, P.O. Box 14100, FI-00076 Aalto (Finland); Seppaelae, E.T., E-mail: eira.seppala@nokia.co [Nokia Research Center, Itaemerenkatu 11-13, FI-00180 Helsinki (Finland); Alava, M.J., E-mail: mikko.alava@tkk.f [Aalto University, Department of Applied Physics, P.O. Box 14100, FI-00076 Aalto (Finland)
2011-05-15
The two-dimensional dipolar Ising model is investigated for the relaxation and dynamics of minor magnetization loops. Monte Carlo simulations show that in a stripe phase an exponential decrease can be found for the magnetization maxima of the loops, M{approx}exp(-{alpha}N{sub l}) where N{sub l} is the number of loops. We discuss the limits of this behavior and its relation to the equilibrium phase diagram of the model.
Cryptography Using Multiple Two-Dimensional Chaotic Maps
Directory of Open Access Journals (Sweden)
Ibrahim S. I. Abuhaiba
2012-08-01
Full Text Available In this paper, a symmetric key block cipher cryptosystem is proposed, involving multiple two-dimensional chaotic maps and using 128-bits external secret key. Computer simulations indicate that the cipher has good diffusion and confusion properties with respect to the plaintext and the key. Moreover, it produces ciphertext with random distribution. The computation time is much less than previous related works. Theoretic analysis verifies its superiority to previous cryptosystems against different types of attacks.
A UNIVERSAL VARIATIONAL FORMULATION FOR TWO DIMENSIONAL FLUID MECHANICS
Institute of Scientific and Technical Information of China (English)
何吉欢
2001-01-01
A universal variational formulation for two dimensional fluid mechanics is obtained, which is subject to the so-called parameter-constrained equations (the relationship between parameters in two governing equations). By eliminating the constraints, the generalized variational principle (GVPs) can be readily derived from the formulation. The formulation can be applied to any conditions in case the governing equations can be converted into conservative forms. Some illustrative examples are given to testify the effectiveness and simplicity of the method.
Nonlocal bottleneck effect in two-dimensional turbulence
Biskamp, D; Schwarz, E
1998-01-01
The bottleneck pileup in the energy spectrum is investigated for several two-dimensional (2D) turbulence systems by numerical simulation using high-order diffusion terms to amplify the effect, which is weak for normal diffusion. For 2D magnetohydrodynamic (MHD) turbulence, 2D electron MHD (EMHD) turbulence and 2D thermal convection, which all exhibit direct energy cascades, a nonlocal behavior is found resulting in a logarithmic enhancement of the spectrum.
Extraction of plant proteins for two-dimensional electrophoresis
Granier, Fabienne
1988-01-01
Three different extraction procedures for two-dimensional electrophoresis of plant proteins are compared: (i) extraction of soluble proteins with a nondenaturing Tris-buffer, (ii) denaturing extraction in presence of sodium dodecyl sulfate at elevated temperature allowing the solubilization of membrane proteins in addition to a recovery of soluble proteins, and (iii) a trichloroacetic acid-acetone procedure allowing the direct precipitation of total proteins.
Lyapunov Computational Method for Two-Dimensional Boussinesq Equation
Mabrouk, Anouar Ben
2010-01-01
A numerical method is developed leading to Lyapunov operators to approximate the solution of two-dimensional Boussinesq equation. It consists of an order reduction method and a finite difference discretization. It is proved to be uniquely solvable and analyzed for local truncation error for consistency. The stability is checked by using Lyapunov criterion and the convergence is studied. Some numerical implementations are provided at the end of the paper to validate the theoretical results.
Complex dynamical invariants for two-dimensional complex potentials
Indian Academy of Sciences (India)
J S Virdi; F Chand; C N Kumar; S C Mishra
2012-08-01
Complex dynamical invariants are searched out for two-dimensional complex potentials using rationalization method within the framework of an extended complex phase space characterized by $x = x_{1} + ip_{3}. y = x_{2} + ip_{4}, p_{x} = p_{1} + ix_{3}, p_{y} = p_{2} + ix_{4}$. It is found that the cubic oscillator and shifted harmonic oscillator admit quadratic complex invariants. THe obtained invariants may be useful for studying non-Hermitian Hamiltonian systems.
Two-dimensional hydrogen negative ion in a magnetic field
Institute of Scientific and Technical Information of China (English)
Xie Wen-Fang
2004-01-01
Making use of the adiabatic hyperspherical approach, we report a calculation for the energy spectrum of the ground and low-excited states of a two-dimensional hydrogen negative ion H- in a magnetic field. The results show that the ground and low-excited states of H- in low-dimensional space are more stable than those in three-dimensional space and there may exist more bound states.
А heuristic algorithm for two-dimensional strip packing problem
Dayong, Cao; Kotov, V.M.
2011-01-01
In this paper, we construct an improved best-fit heuristic algorithm for two-dimensional rectangular strip packing problem (2D-RSPP), and compare it with some heuristic and metaheuristic algorithms from literatures. The experimental results show that BFBCC could produce satisfied packing layouts than these methods, especially for the large problem of 50 items or more, BFBCC could get better results in shorter time.
Chronology Protection in Two-Dimensional Dilaton Gravity
Mishima, T; Mishima, Takashi; Nakamichi, Akika
1994-01-01
The global structure of 1 + 1 dimensional compact Universe is studied in two-dimensional model of dilaton gravity. First we give a classical solution corresponding to the spacetime in which a closed time-like curve appears, and show the instability of this spacetime due to the existence of matters. We also observe quantum version of such a spacetime having closed timelike curves never reappear unless the parameters are fine-tuned.
Phase Transitions in Two-Dimensional Traffic Flow Models
Cuesta, J A; Molera, J M; Cuesta, José A; Martinez, Froilán C; Molera, Juan M
1993-01-01
Abstract: We introduce two simple two-dimensional lattice models to study traffic flow in cities. We have found that a few basic elements give rise to the characteristic phase diagram of a first-order phase transition from a freely moving phase to a jammed state, with a critical point. The jammed phase presents new transitions corresponding to structural transformations of the jam. We discuss their relevance in the infinite size limit.
Phase Transitions in Two-Dimensional Traffic Flow Models
Cuesta, José A; Molera, Juan M; Escuela, Angel Sánchez; 10.1103/PhysRevE.48.R4175
2009-01-01
We introduce two simple two-dimensional lattice models to study traffic flow in cities. We have found that a few basic elements give rise to the characteristic phase diagram of a first-order phase transition from a freely moving phase to a jammed state, with a critical point. The jammed phase presents new transitions corresponding to structural transformations of the jam. We discuss their relevance in the infinite size limit.
SU(1,2) invariance in two-dimensional oscillator
Krivonos, Sergey
2016-01-01
Performing the Hamiltonian analysis we explicitly established the canonical equivalence of the deformed oscillator, constructed in arXiv:1607.03756[hep-th], with the ordinary one. As an immediate consequence, we proved that the SU(1,2) symmetry is the dynamical symmetry of the ordinary two-dimensional oscillator. The characteristic feature of this SU(1,2) symmetry is a non-polynomial structure of its generators written it terms of the oscillator variables.
Multiple Potts Models Coupled to Two-Dimensional Quantum Gravity
Baillie, C F
1992-01-01
We perform Monte Carlo simulations using the Wolff cluster algorithm of {\\it multiple} $q=2,3,4$ state Potts models on dynamical phi-cubed graphs of spherical topology in order to investigate the $c>1$ region of two-dimensional quantum gravity. Contrary to naive expectation we find no obvious signs of pathological behaviour for $c>1$. We discuss the results in the light of suggestions that have been made for a modified DDK ansatz for $c>1$.
Multiple Potts models coupled to two-dimensional quantum gravity
Baillie, C. F.; Johnston, D. A.
1992-07-01
We perform Monte Carlo simulations using the Wolff cluster algorithm of multiple q=2, 3, 4 state Potts models on dynamical phi-cubed graphs of spherical topology in order to investigate the c>1 region of two-dimensional quantum gravity. Contrary to naive expectation we find no obvious signs of pathological behaviour for c>1. We discuss the results in the light of suggestions that have been made for a modified DDK ansatz for c>1.
Colloidal interactions in two-dimensional nematic emulsions
Indian Academy of Sciences (India)
N M Silvestre; P Patrício; M M Telo Da Gama
2005-06-01
We review theoretical and experimental work on colloidal interactions in two-dimensional (2D) nematic emulsions. We pay particular attention to the effects of (i) the nematic elastic constants, (ii) the size of the colloids, and (iii) the boundary conditions at the particles and the container. We consider the interactions between colloids and fluid (deformable) interfaces and the shape of fluid colloids in smectic-C films.
Thermal diode from two-dimensional asymmetrical Ising lattices.
Wang, Lei; Li, Baowen
2011-06-01
Two-dimensional asymmetrical Ising models consisting of two weakly coupled dissimilar segments, coupled to heat baths with different temperatures at the two ends, are studied by Monte Carlo simulations. The heat rectifying effect, namely asymmetric heat conduction, is clearly observed. The underlying mechanisms are the different temperature dependencies of thermal conductivity κ at two dissimilar segments and the match (mismatch) of flipping frequencies of the interface spins.
Numerical Study of Two-Dimensional Viscous Flow over Dams
Institute of Scientific and Technical Information of China (English)
王利兵; 刘宇陆; 涂敏杰
2003-01-01
In this paper, the characteristics of two-dimensional viscous flow over two dams were numerically investigated. The results show that the behavior of the vortices is closely related to the space between two dams, water depth, Fr number and Reynolds number. In addition, the flow properties behind each dam are different, and the changes over two dams are more complex than over one dam. Finally, the relevant turbulent characteristics were analyzed.
Spirals and Skyrmions in two dimensional oxide heterostructures.
Li, Xiaopeng; Liu, W Vincent; Balents, Leon
2014-02-14
We construct the general free energy governing long-wavelength magnetism in two dimensional oxide heterostructures, which applies irrespective of the microscopic mechanism for magnetism. This leads, in the relevant regime of weak but non-negligible spin-orbit coupling, to a rich phase diagram containing in-plane ferromagnetic, spiral, cone, and Skyrmion lattice phases, as well as a nematic state stabilized by thermal fluctuations.
Acoustic Bloch oscillations in a two-dimensional phononic crystal.
He, Zhaojian; Peng, Shasha; Cai, Feiyan; Ke, Manzhu; Liu, Zhengyou
2007-11-01
We report the observation of acoustic Bloch oscillations at megahertz frequency in a two-dimensional phononic crystal. By creating periodically arrayed cavities with a decreasing gradient in width along one direction in the phononic crystal, acoustic Wannier-Stark ladders are created in the frequency domain. The oscillatory motion of an incident Gaussian pulse inside the sample is demonstrated by both simulation and experiment.
Exact analytic flux distributions for two-dimensional solar concentrators.
Fraidenraich, Naum; Henrique de Oliveira Pedrosa Filho, Manoel; Vilela, Olga C; Gordon, Jeffrey M
2013-07-01
A new approach for representing and evaluating the flux density distribution on the absorbers of two-dimensional imaging solar concentrators is presented. The formalism accommodates any realistic solar radiance and concentrator optical error distribution. The solutions obviate the need for raytracing, and are physically transparent. Examples illustrating the method's versatility are presented for parabolic trough mirrors with both planar and tubular absorbers, Fresnel reflectors with tubular absorbers, and V-trough mirrors with planar absorbers.
Tricritical behavior in a two-dimensional field theory
Hamber, Herbert
1980-05-01
The critical behavior of a two-dimensional scalar Euclidean field theory with a potential term that allows for three minima is analyzed using an approximate position-space renormalization-group transformation on the equivalent quantum spin Hamiltonian. The global phase diagram shows a tricritical point separating a critical line from a line of first-order transitions. Other critical properties are examined, and good agreement is found with results on classical spin models belonging to the same universality class.
Quantum entanglement in a two-dimensional ion trap
Institute of Scientific and Technical Information of China (English)
王成志; 方卯发
2003-01-01
In this paper, we investigate the quantum entanglement in a two-dimensional ion trap system. We discuss the quantum entanglement between the ion and phonons by using reduced entropy, and that between two degrees of freedom of the vibrational motion along x and y directions by using quantum relative entropy. We discuss also the influence of initial state of the system on the quantum entanglement and the relation between two entanglements in the trapped ion system.
Coll Positioning systems: a two-dimensional approach
Ferrando, J J
2006-01-01
The basic elements of Coll positioning systems (n clocks broadcasting electromagnetic signals in a n-dimensional space-time) are presented in the two-dimensional case. This simplified approach allows us to explain and to analyze the properties and interest of these relativistic positioning systems. The positioning system defined in flat metric by two geodesic clocks is analyzed. The interest of the Coll systems in gravimetry is pointed out.
Interior design of a two-dimensional semiclassic black hole
Levanony, Dana; 10.1103/PhysRevD.80.084008
2009-01-01
We look into the inner structure of a two-dimensional dilatonic evaporating black hole. We establish and employ the homogenous approximation for the black-hole interior. The field equations admit two types of singularities, and their local asymptotic structure is investigated. One of these singularities is found to develop, as a spacelike singularity, inside the black hole. We then study the internal structure of the evaporating black hole from the horizon to the singularity.
Towards a two dimensional model of surface piezoelectricity
Monge Víllora, Oscar
2016-01-01
We want to understand the behaviour of flexoelectricity and surface piezoelectricity and distinguish them in order to go deep into the controversies of the filed. This motivate the construction of a model of continuum flexoelectric theory. The model proposed is a two-dimensional model that integrates the electromechanical equations that include the elastic, dielectric, piezoelectric and flexoelectric effect on a rectangular sample. As the flexoelectric and the surface piezoelectric effects ap...
Velocity Statistics in the Two-Dimensional Granular Turbulence
Isobe, Masaharu
2003-01-01
We studied the macroscopic statistical properties on the freely evolving quasi-elastic hard disk (granular) system by performing a large-scale (up to a few million particles) event-driven molecular dynamics systematically and found that remarkably analogous to an enstrophy cascade process in the decaying two-dimensional fluid turbulence. There are four typical stages in the freely evolving inelastic hard disk system, which are homogeneous, shearing (vortex), clustering and final state. In the...
Statistical study of approximations to two dimensional inviscid turbulence
Energy Technology Data Exchange (ETDEWEB)
Glaz, H.M.
1977-09-01
A numerical technique is developed for studying the ergodic and mixing hypotheses for the dynamical systems arising from the truncated Fourier transformed two-dimensional inviscid Navier-Stokes equations. This method has the advantage of exactly conserving energy and entropy (i.e., total vorticity) in the inviscid case except for numerical error in solving the ordinary differential equations. The development of the mathematical model as an approximation to a real physical (turbulent) flow and the numerical results obtained are discussed.
Static Structure of Two-Dimensional Granular Chain
Institute of Scientific and Technical Information of China (English)
WEN Ping-Ping; LI Liang-Sheng; ZHENG Ning; SHI Qing-Fan
2010-01-01
@@ Static packing structures of two-dimensional granular chains are investigated experimentally.It is shown that the packing density approximates the saturation with the exponential law as the length of chain increases.The packing structures are globally disordered,while the local square crystallization is found by using the radial distribution function.This characteristic phase of chain packing is similar to a liquid crystal state,and has properties between a conventional liquid and solid crystal.
THE DEGENERACY PROBLEM OF TWO-DIMENSIONAL LINEAR RECURRING ARRAYS
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The degeneracy degree and degeneracy position sets of a wo-dimensional linear recurrence relation set are characterized. The fact that a linear recurring array is essentially a doubly periodic array is shown. By using the Grbner base theory, a calculation formula for degeneracy degree is given and the existence of a special degeneracy position set is proved. In the present paper, the degeneracy problem of the two-dimensional linear recurring arrays is completely solved.
Two-Dimensional, High Flow, Precisely Controlled Monodisperse Drop Source
1993-03-15
pro - duces a small effect on the undriven sheet. When the spatial perturbations are combined with temporal perturbations (the acous- tic drive), the...Industrial Park Road Medway MA 02053 Telephone 800-255-8823 Distributor of tubing and fittings Laser drilling of small nozzles 22. Mikros
Two-Dimensional Identification of Fetal Tooth Germs.
Seabra, Mariana; Vaz, Paula; Valente, Francisco; Braga, Ana; Felino, António
2017-03-01
To demonstrate the efficiency and applicability of two-dimensional ultrasonography in the identification of tooth germs and in the assessment of potential pathology. Observational, descriptive, cross-sectional study. Prenatal Diagnosis Unit of Centro Hospitalar de Vila Nova de Gaia / Espinho-Empresa Pública in Portugal. A total of 157 white pregnant women (median age, 32 years; range, 14 to 47 years) undergoing routine ultrasound exams. Description of the fetal tooth germs, as visualized by two-dimensional ultrasonography, including results from prior fetal biometry and detailed screening for malformations. In the first trimester group, ultrasonography identified 10 tooth germs in the maxilla and 10 tooth germs in the mandible in all fetuses except for one who presented eight maxillary tooth germs. This case was associated with a chromosomal abnormality (trisomy 13) with a bilateral cleft palate. In the second and third trimesters group, ultrasonography identified a larger range of tooth germs: 81.2% of fetuses showed 10 tooth germs in the maxilla and 85.0% of fetuses had 10 tooth germs in the mandible. Hypodontia was more prevalent in the maxilla than in the mandible, which led us to use qualitative two-dimensional ultrasonography to analyze the possible association between hypodontia and other variables such as fetal pathology, markers, head, nuchal, face, and spine. We recommend using this method as the first exam to evaluate fetal morphology and also to help establish accurate diagnosis of abnormalities in pregnancy.
Electromagnetically induced two-dimensional grating assisted by incoherent pump
Energy Technology Data Exchange (ETDEWEB)
Chen, Yu-Yuan; Liu, Zhuan-Zhuan; Wan, Ren-Gang, E-mail: wrg@snnu.edu.cn
2017-04-25
We propose a scheme for realizing electromagnetically induced two-dimensional grating in a double-Λ system driven simultaneously by a coherent field and an incoherent pump field. In such an atomic configuration, the absorption is suppressed owing to the incoherent pumping process and the probe can be even amplified, while the refractivity is mainly attributed to the dynamically induced coherence. With the help of a standing-wave pattern coherent field, we obtain periodically modulated refractive index without or with gain, and therefore phase grating or gain-phase grating which diffracts a probe light into high-order direction efficiently can be formed in the medium via appropriate manipulation of the system parameters. The diffraction efficiency attainable by the present gratings can be controlled by tuning the coherent field intensity or the interaction length. Hence, the two-dimensional grating can be utilized as all-optical splitter or router in optical networking and communication. - Highlights: • Two-dimensional grating is coherently induced in four-level atoms. • Phase and gain-phase gratings are obtained assisted by incoherent pump. • The diffraction power is improved due to the enhanced refraction modulation. • The gratings can be utilized as multi-channel all-optical splitter and router.
a First Cryptosystem for Security of Two-Dimensional Data
Mishra, D. C.; Sharma, Himani; Sharma, R. K.; Kumar, Naveen
In this paper, we present a novel technique for security of two-dimensional data with the help of cryptography and steganography. The presented approach provides multilayered security of two-dimensional data. First layer security was developed by cryptography and second layer by steganography. The advantage of steganography is that the intended secret message does not attract attention to itself as an object of scrutiny. This paper proposes a novel approach for encryption and decryption of information in the form of Word Data (.doc file), PDF document (.pdf file), Text document, Gray-scale images, and RGB images, etc. by using Vigenere Cipher (VC) associated with Discrete Fourier Transform (DFT) and then hiding the data behind the RGB image (i.e. steganography). Earlier developed techniques provide security of either PDF data, doc data, text data or image data, but not for all types of two-dimensional data and existing techniques used either cryptography or steganography for security. But proposed approach is suitable for all types of data and designed for security of information by cryptography and steganography. The experimental results for Word Data, PDF document, Text document, Gray-scale images and RGB images support the robustness and appropriateness for secure transmission of these data. The security analysis shows that the presented technique is immune from cryptanalytic. This technique further provides security while decryption as a check on behind which RGB color the information is hidden.
Two-dimensional capillary electrophoresis using tangentially connected capillaries.
Sahlin, Eskil
2007-06-22
A novel type of fused silica capillary system is described where channels with circular cross-sections are tangentially in contact with each other and connected through a small opening at the contact area. Since the channels are not crossing each other in the same plane, the capillaries can easily be filled with different solutions, i.e. different solutions will be in contact with each other at the contact point. The system has been used to perform different types of two-dimensional separations and the complete system is fully automated where a high voltage switch is used to control the location of the high voltage in the system. Using two model compounds it is demonstrated that a type of two-dimensional separation can be performed using capillary zone electrophoresis at two different pH values. It is also shown that a compound with acid/base properties can be concentrated using a dynamic pH junction mechanism when transferred from the first separation to the second separation. In addition, the system has been used to perform a comprehensive two-dimensional capillary electrophoresis separation of tryptic digest of bovine serum albumin using capillary zone electrophoresis followed by micellar electrokinetic chromatography.
Procedures for two-dimensional electrophoresis of proteins
Energy Technology Data Exchange (ETDEWEB)
Tollaksen, S.L.; Giometti, C.S.
1996-10-01
High-resolution two-dimensional gel electrophoresis (2DE) of proteins, using isoelectric focusing in the first dimension and sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) in the second, was first described in 1975. In the 20 years since those publications, numerous modifications of the original method have evolved. The ISO-DALT system of 2DE is a high-throughput approach that has stood the test of time. The problem of casting many isoelectric focusing gels and SDS-PAGE slab gels (up to 20) in a reproducible manner has been solved by the use of the techniques and equipment described in this manual. The ISO-DALT system of two-dimensional gel electrophoresis originated in the late 1970s and has been modified many times to improve its high-resolution, high-throughput capabilities. This report provides the detailed procedures used with the current ISO-DALT system to prepare, run, stain, and photograph two-dimensional gels for protein analysis.
A two-dimensional analytical model of petroleum vapor intrusion
Yao, Yijun; Verginelli, Iason; Suuberg, Eric M.
2016-02-01
In this study we present an analytical solution of a two-dimensional petroleum vapor intrusion model, which incorporates a steady-state diffusion-dominated vapor transport in a homogeneous soil and piecewise first-order aerobic biodegradation limited by oxygen availability. This new model can help practitioners to easily generate two-dimensional soil gas concentration profiles for both hydrocarbons and oxygen and estimate hydrocarbon indoor air concentrations as a function of site-specific conditions such as source strength and depth, reaction rate constant, soil characteristics and building features. The soil gas concentration profiles generated by this new model are shown in good agreement with three-dimensional numerical simulations and two-dimensional measured soil gas data from a field study. This implies that for cases involving diffusion dominated soil gas transport, steady state conditions and homogenous source and soil, this analytical model can be used as a fast and easy-to-use risk screening tool by replicating the results of 3-D numerical simulations but with much less computational effort.
Strongly correlated two-dimensional plasma explored from entropy measurements.
Kuntsevich, A Y; Tupikov, Y V; Pudalov, V M; Burmistrov, I S
2015-06-23
Charged plasma and Fermi liquid are two distinct states of electronic matter intrinsic to dilute two-dimensional electron systems at elevated and low temperatures, respectively. Probing their thermodynamics represents challenge because of lack of an adequate technique. Here, we report a thermodynamic method to measure the entropy per electron in gated structures. Our technique appears to be three orders of magnitude superior in sensitivity to a.c. calorimetry, allowing entropy measurements with only 10(8) electrons. This enables us to investigate the correlated plasma regime, previously inaccessible experimentally in two-dimensional electron systems in semiconductors. In experiments with clean two-dimensional electron system in silicon-based structures, we traced entropy evolution from the plasma to Fermi liquid regime by varying electron density. We reveal that the correlated plasma regime can be mapped onto the ordinary non-degenerate Fermi gas with an interaction-enhanced temperature-dependent effective mass. Our method opens up new horizons in studies of low-dimensional electron systems.
Augmented reality simulator for training in two-dimensional echocardiography.
Weidenbach, M; Wick, C; Pieper, S; Quast, K J; Fox, T; Grunst, G; Redel, D A
2000-02-01
In two-dimensional echocardiography the sonographer must synthesize multiple tomographic slices into a mental three-dimensional (3D) model of the heart. Computer graphics and virtual reality environments are ideal to visualize complex 3D spatial relationships. In augmented reality (AR) applications, real and virtual image data are linked, to increase the information content. In the presented AR simulator a 3D surface model of the human heart is linked with echocardiographic volume data sets. The 3D echocardiographic data sets are registered with the heart model to establish spatial and temporal congruence. The heart model, together with an animated ultrasound sector represents a reference scenario, which displays the currently selected two-dimensional echocardiographic cutting plane calculated from the volume data set. Modifications of the cutting plane within the echocardiographic data are transferred and visualized simultaneously and in real time within the reference scenario. The trainee can interactively explore the 3D heart model and the registered 3D echocardiographic data sets by an animated ultrasound probe, whose position is controlled by an electromagnetic tracking system. The tracking system is attached to a dummy transducer and placed on a plastic puppet to give a realistic impression of a two-dimensional echocardiographic examination.
Experimental realization of two-dimensional boron sheets.
Feng, Baojie; Zhang, Jin; Zhong, Qing; Li, Wenbin; Li, Shuai; Li, Hui; Cheng, Peng; Meng, Sheng; Chen, Lan; Wu, Kehui
2016-06-01
A variety of two-dimensional materials have been reported in recent years, yet single-element systems such as graphene and black phosphorus have remained rare. Boron analogues have been predicted, as boron atoms possess a short covalent radius and the flexibility to adopt sp(2) hybridization, features that favour the formation of two-dimensional allotropes, and one example of such a borophene material has been reported recently. Here, we present a parallel experimental work showing that two-dimensional boron sheets can be grown epitaxially on a Ag(111) substrate. Two types of boron sheet, a β12 sheet and a χ3 sheet, both exhibiting a triangular lattice but with different arrangements of periodic holes, are observed by scanning tunnelling microscopy. Density functional theory simulations agree well with experiments, and indicate that both sheets are planar without obvious vertical undulations. The boron sheets are quite inert to oxidization and interact only weakly with their substrate. We envisage that such boron sheets may find applications in electronic devices in the future.
Two-dimensional oxides: multifunctional materials for advanced technologies.
Pacchioni, Gianfranco
2012-08-13
The last decade has seen spectacular progress in the design, preparation, and characterization down to the atomic scale of oxide ultrathin films of few nanometers thickness grown on a different material. This has paved the way towards several sophisticated applications in advanced technologies. By playing around with the low-dimensionality of the oxide layer, which sometimes leads to truly two-dimensional systems, one can exploit new properties and functionalities that are not present in the corresponding bulk materials or thick films. In this review we provide some clues about the most recent advances in the design of these systems based on modern electronic structure theory and on their preparation and characterization with specifically developed growth techniques and analytical methods. We show how two-dimensional oxides can be used in mature technologies by providing added value to existing materials, or in new technologies based on completely new paradigms. The fields in which two-dimensional oxides are used are classified based on the properties that are exploited, chemical or physical. With respect to chemical properties we discuss use of oxide ultrathin films in catalysis, solid oxide fuel cells, gas sensors, corrosion protection, and biocompatible materials; regarding the physical properties we discuss metal-oxide field effect transistors and memristors, spintronic devices, ferroelectrics and thermoelectrics, and solar energy materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Directory of Open Access Journals (Sweden)
D. A. Fetisov
2015-01-01
Full Text Available The controllability conditions are well known if we speak about linear stationary systems: a linear stationary system is controllable if and only if the dimension of the state vector is equal to the rank of the controllability matrix. The concept of the controllability matrix is extended to affine systems, but relations between affine systems controllability and properties of this matrix are more complicated. Various controllability conditions are set for affine systems, but they deal as usual either with systems of some special form or with controllability in some small neighborhood of the concerned point. An affine system is known to be controllable if the system is equivalent to a system of a canonical form, which is defined and regular in the whole space of states. In this case, the system is said to be feedback linearizable in the space of states. However there are examples, which illustrate that a system can be controllable even if it is not feedback linearizable in any open subset in the space of states. In this article we deal with such systems.Affine systems with two-dimensional control are considered. The system in question is assumed to be equivalent to a system of a quasicanonical form with two-dimensional zero dynamics which is defined and regular in the whole space of states. Therefore the controllability of the original system is equivalent to the controllability of the received system of a quasicanonical form. In this article the sufficient condition for an available solution of the terminal problem is proven for systems of a quasicanonical form with two-dimensional control and two-dimensional zero dynamics. The condition is valid in the case of an arbitrary time interval and arbitrary initial and finite states of the system. Therefore the controllability condition is set for systems of a quasicanonical form with two-dimensional control and two-dimensional zero dynamics. An example is given which illustrates how the proved
Energy Technology Data Exchange (ETDEWEB)
Considine, D.B.; Douglass, A.R.; Jackman, C.H. [Applied Research Corp., Landover, MD (United States)]|[NASA, Goddard Space Flight Center, Greenbelt, MD (United States)
1995-02-01
The Goddard Space Flight Center (GSFC) two-dimensional model of stratospheric photochemistry and dynamics has been used to calculate the O3 response to stratospheric aircraft (high-speed civil transport (HSCT)) emissions. The sensitivity of the model O3 response was examined for systematic variations of five parameters and two reaction rates over a wide range, expanding on calculations by various modeling groups for the NASA High Speed Research Program and the World Meteorological Organization. In all, 448 model runs were required to test the effects of variations in the latitude, altitude, and magnetitude of the aircraft emissions perturbation, the background chlorine levels, the background sulfate aerosol surface area densities, and the rates of two key reactions. No deviation from previous conclusions concerning the response of O3 to HSCTs was found in this more exhaustive exploration of parameter space. Maximum O3 depletions occur for high-altitude, low altitude HSCT perturbations. Small increases in global total O3 can occur for low-altitude, high-altitude injections. Decreasing aerosol surface area densities and background chlorine levels increases the sensitivity of model O3 to the HSCT perturbations. The location of the aircraft emissions is the most important determinant of the model response. Response to the location of the HSCT emissions is not changed qualitatively by changes in background chlorine and aerosol loading. The response is also not very sensitive to changes in the rates of the reactions NO + HO2 yields NO2 + OH and HO2 + O3 yields OH + 2O2 over the limits of their respective uncertainties. Finally, levels of lower stratospheric HO(sub x) generally decrease when the HSCT perturbation is included, even though there are large increases in H2O due to the perturbation.
Upper Semicontinuity of Attractors for a Non-Newtonian Fluid under Small Random Perturbations
Directory of Open Access Journals (Sweden)
Jianxin Luo
2014-01-01
Full Text Available This paper investigates the limiting behavior of attractors for a two-dimensional incompressible non-Newtonian fluid under small random perturbations. Under certain conditions, the upper semicontinuity of the attractors for diminishing perturbations is shown.
Institute of Scientific and Technical Information of China (English)
XU Quan; TIAN Qiang
2009-01-01
We restrict our attention to the discrete two-dimensional monatomic β-FPU lattice. We look for twodimensional breather lattice solutions and two-dimensional compact-like discrete breathers by using trying method and analyze their stability by using Aubry's linearly stable theory. We obtain the conditions of existence and stability of two-dimensional breather lattice solutions and two-dimensional compact-like discrete breathers in the discrete twodimensional monatomic β-FPU lattice.
Numerical Simulation of the Flow around Two-dimensional Partially Cavitating Hydrofoils
Institute of Scientific and Technical Information of China (English)
Fahri Celik; Yasemin Arikan Ozden; Sakir Bal
2014-01-01
In the present study, a new approach is applied to the cavity prediction for two-dimensional (2D) hydrofoils by the potential based boundary element method (BEM). The boundary element method is treated with the source and doublet distributions on the panel surface and cavity surface by the use of the Dirichlet type boundary conditions. An iterative solution approach is used to determine the cavity shape on partially cavitating hydrofoils. In the case of a specified cavitation number and cavity length, the iterative solution method proceeds by addition or subtraction of a displacement thickness on the cavity surface of the hydrofoil. The appropriate cavity shape is obtained by the dynamic boundary condition of the cavity surface and the kinematic boundary condition of the whole foil surface including the cavity. For a given cavitation number the cavity length of the 2D hydrofoil is determined according to the minimum error criterion among different cavity lengths, which satisfies the dynamic boundary condition on the cavity surface. The NACA 16006, NACA 16012 and NACA 16015 hydrofoil sections are investigated for two angles of attack. The results are compared with other potential based boundary element codes, the PCPAN and a commercial CFD code (FLUENT). Consequently, it has been shown that the results obtained from the two dimensional approach are consistent with those obtained from the others.
Numerical simulation of the flow around two-dimensional partially cavitating hydrofoils
Celik, Fahri; Ozden, Yasemin Arikan; Bal, Sakir
2014-09-01
In the present study, a new approach is applied to the cavity prediction for two-dimensional (2D) hydrofoils by the potential based boundary element method (BEM). The boundary element method is treated with the source and doublet distributions on the panel surface and cavity surface by the use of the Dirichlet type boundary conditions. An iterative solution approach is used to determine the cavity shape on partially cavitating hydrofoils. In the case of a specified cavitation number and cavity length, the iterative solution method proceeds by addition or subtraction of a displacement thickness on the cavity surface of the hydrofoil. The appropriate cavity shape is obtained by the dynamic boundary condition of the cavity surface and the kinematic boundary condition of the whole foil surface including the cavity. For a given cavitation number the cavity length of the 2D hydrofoil is determined according to the minimum error criterion among different cavity lengths, which satisfies the dynamic boundary condition on the cavity surface. The NACA 16006, NACA 16012 and NACA 16015 hydrofoil sections are investigated for two angles of attack. The results are compared with other potential based boundary element codes, the PCPAN and a commercial CFD code (FLUENT). Consequently, it has been shown that the results obtained from the two dimensional approach are consistent with those obtained from the others.
Two Dimensional Subsonic Euler Flows Past a Wall or a Symmetric Body
Chen, Chao; Du, Lili; Xie, Chunjing; Xin, Zhouping
2016-08-01
The existence and uniqueness of two dimensional steady compressible Euler flows past a wall or a symmetric body are established. More precisely, given positive convex horizontal velocity in the upstream, there exists a critical value {ρ_cr} such that if the incoming density in the upstream is larger than {ρ_cr}, then there exists a subsonic flow past a wall. Furthermore, {ρ_cr} is critical in the sense that there is no such subsonic flow if the density of the incoming flow is less than {ρ_cr}. The subsonic flows possess large vorticity and positive horizontal velocity above the wall except at the corner points on the boundary. Moreover, the existence and uniqueness of a two dimensional subsonic Euler flow past a symmetric body are also obtained when the incoming velocity field is a general small perturbation of a constant velocity field and the density of the incoming flow is larger than a critical value. The asymptotic behavior of the flows is obtained with the aid of some integral estimates for the difference between the velocity field and its far field states.
Surface science using radioactive ions at ISOLDE: from metal surfaces to two-dimensional materials
Potzger, K.; E Mølholt, T.; Fenta, A. S.; Pereira, L. M. C.
2017-06-01
We review the research carried out using the apparatus for surface physics and interfaces (ASPIC), at ISOLDE, CERN. We give an overview of the research highlights since 2000, focusing on magnetic and non-magnetic metallic surfaces, and introduce the scientific program that will follow the upgrade which is currently underway, focusing on two-dimensional materials. ASPIC was formerly used for the growth of ultrathin metallic films and their characterization by means of perturbed angular correlation spectroscopy. Past research has mainly focused on the determination of the magnetic hyperfine field at the probe atom located on different sites at the surface such as terraces, kinks, steps as well as on the investigation of the static magnetic polarization at the interface between ferromagnetic and paramagnetic layers. Future research on two-dimensional materials using ASPIC is foreseen to focus on the investigation of structural and electronic properties of adatoms (adsorption sites, hybridization effects, intra-atomic charge transfer, magnetic moments, etc). We emphasize, in this context, the exceptional capabilities of ASPIC in terms of broad applicability, high precision and low detection limits.
Beatification: Flattening the Poisson Bracket for Two-Dimensional Fluid and Plasma Theories
Viscondi, Thiago F; Morrison, Philip J
2016-01-01
A perturbative method called beatification is presented for a class of two-dimensional fluid and plasma theories. The Hamiltonian systems considered, namely the Euler, Vlasov-Poisson, Hasegawa-Mima, and modified Hasegawa-Mima equations, are naturally described in terms of noncanonical variables. The beatification procedure amounts to finding the correct transformation that removes the explicit variable dependence from a noncanonical Poisson bracket and replaces it with a fixed dependence on a chosen state in phase space. As such, beatification is a major step toward casting the Hamiltonian system in its canonical form, thus enabling or facilitating the use of analytical and numerical techniques that require or favor a representation in terms of canonical, or beatified, Hamiltonian variables.
2DCOS and I. Three decades of two-dimensional correlation spectroscopy
Noda, Isao
2016-11-01
Historical and personal accounts of the development of two-dimensional correlation spectroscopy (2DCOS) in the last 30 years are presented. 2DCOS originally started as a data sorting technique developed specifically for dynamic IR linear dichroism (DIRLD) spectra of polymers observed under a small amplitude sinusoidal strain. The concept was later generalized to provide a surprisingly versatile analytical tool to study many different types of samples under the influence of not only dynamic but also various static perturbations. Introduction of the efficient computational method based on discrete Hilbert transform and availability of software, as well as the comprehensive textbook in the field, have made the widespread and continuously growing use of 2DCOS technique possible. Evolution of the technique to incorporate new and variant forms of 2DCOS is also noted.
Sunahara, Y.; Kojima, F.
1988-01-01
The purpose of this paper is to establish a method for identifying unknown parameters involved in the boundary state of a class of diffusion systems under noisy observations. A mathematical model of the system dynamics is given by a two-dimensional diffusion equation. Noisy observations are made by sensors allocated on the system boundary. Starting with the mathematical model mentioned above, an online parameter estimation algorithm is proposed within the framework of the maximum likelihood estimation. Existence of the optimal solution and related necessary conditions are discussed. By solving a local variation of the cost functional with respect to the perturbation of parameters, the estimation mechanism is proposed in a form of recursive computations. Finally, the feasibility of the estimator proposed here is demonstrated through results of digital simulation experiments.
Two-dimensional cylindrical ion-acoustic solitary and rogue waves in ultrarelativistic plasmas
Energy Technology Data Exchange (ETDEWEB)
Ata-ur-Rahman [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Centre for Physics at QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics at QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Mushtaq, A. [National Centre for Physics at QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan)
2013-07-15
The propagation of ion-acoustic (IA) solitary and rogue waves is investigated in a two-dimensional ultrarelativistic degenerate warm dense plasma. By using the reductive perturbation technique, the cylindrical Kadomtsev–Petviashvili (KP) equation is derived, which can be further transformed into a Korteweg–de Vries (KdV) equation. The latter admits a solitary wave solution. However, when the frequency of the carrier wave is much smaller than the ion plasma frequency, the KdV equation can be transferred to a nonlinear Schrödinger equation to study the nonlinear evolution of modulationally unstable modified IA wavepackets. The propagation characteristics of the IA solitary and rogue waves are strongly influenced by the variation of different plasma parameters in an ultrarelativistic degenerate dense plasma. The present results might be helpful to understand the nonlinear electrostatic excitations in astrophysical degenerate dense plasmas.
Two-Dimensional Bumps in Piecewise Smooth Neural Fields with Synaptic Depression
Bressloff, Paul C.
2011-01-01
We analyze radially symmetric bumps in a two-dimensional piecewise-smooth neural field model with synaptic depression. The continuum dynamics is described in terms of a nonlocal integrodifferential equation, in which the integral kernel represents the spatial distribution of synaptic weights between populations of neurons whose mean firing rate is taken to be a Heaviside function of local activity. Synaptic depression dynamically reduces the strength of synaptic weights in response to increases in activity. We show that in the case of a Mexican hat weight distribution, sufficiently strong synaptic depression can destabilize a stationary bump solution that would be stable in the absence of depression. Numerically it is found that the resulting instability leads to the formation of a traveling spot. The local stability of a bump is determined by solutions to a system of pseudolinear equations that take into account the sign of perturbations around the circular bump boundary. © 2011 Society for Industrial and Applied Mathematics.
Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor
Branny, Artur; Kumar, Santosh; Proux, Raphaël; Gerardot, Brian D
2017-01-01
An outstanding challenge in quantum photonics is scalability, which requires positioning of single quantum emitters in a deterministic fashion. Site positioning progress has been made in established platforms including defects in diamond and self-assembled quantum dots, albeit often with compromised coherence and optical quality. The emergence of single quantum emitters in layered transition metal dichalcogenide semiconductors offers new opportunities to construct a scalable quantum architecture. Here, using nanoscale strain engineering, we deterministically achieve a two-dimensional lattice of quantum emitters in an atomically thin semiconductor. We create point-like strain perturbations in mono- and bi-layer WSe2 which locally modify the band-gap, leading to efficient funnelling of excitons towards isolated strain-tuned quantum emitters that exhibit high-purity single photon emission. We achieve near unity emitter creation probability and a mean positioning accuracy of 120±32 nm, which may be improved with further optimization of the nanopillar dimensions. PMID:28530219
Zeeman-Field-Tuned Topological Phase Transitions in a Two-Dimensional Class-DIII Superconductor.
Deng, W Y; Geng, H; Luo, W; Sheng, L; Xing, D Y
2016-01-01
We investigate the topological phase transitions in a two-dimensional time-reversal invariant topological superconductor in the presence of a Zeeman field. Based on the spin Chern number theory, we find that the system exhibits a number of topologically distinct phases with changing the out-of-plane component of the Zeeman field, including a quantum spin Hall-like phase, quantum anomalous Hall-like phases with total Chern number C = -2, -1, 1 and 2, and a topologically trivial superconductor phase. The BdG band gap closes at each boundary of the phase transitions. Furthermore, we demonstrate that the zero bias conductance provides clear transport signatures of the different topological phases, which are robust against symmetry-breaking perturbations.
Two-dimensional silica: Structural, mechanical properties, and strain-induced band gap tuning
Energy Technology Data Exchange (ETDEWEB)
Gao, Enlai; Xie, Bo [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); Xu, Zhiping, E-mail: xuzp@tsinghua.edu.cn [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)
2016-01-07
Two-dimensional silica is of rising interests not only for its practical applications as insulating layers in nanoelectronics, but also as a model material to understand crystals and glasses. In this study, we examine structural and electronic properties of hexagonal and haeckelite phases of silica bilayers by performing first-principles calculations. We find that the corner-sharing SiO{sub 4} tetrahedrons in these two phases are locally similar. The robustness and resilience of these tetrahedrons under mechanical perturbation allow effective strain engineering of the electronic structures with band gaps covering a very wide range, from of that for insulators, to wide-, and even narrow-gap semiconductors. These findings suggest that the flexible 2D silica holds great promises in developing nanoelectronic devices with strain-tunable performance, and lay the ground for the understanding of crystalline and vitreous phases in 2D, where bilayer silica provides an ideal test-bed.
Velocity selection at large undercooling in a two-dimensional nonlocal model of solidification
Barbieri, Angelo
1987-01-01
The formation of needle-crystal dendrites from an undercooled melt is investigated analytically, applying the method of Caroli et al. (1986) to Langer's (1980) symmetric two-dimensional nonlocal model of solidification with finite anisotropy in the limit of large undercooling. A solution based on the WKB approximation is obtained, and a saddle-point evaluation is performed. It is shown that needle-crystal solutions exist only if the capillary anisotropy is nonzero, in which case a particular value of the growth velocity can be selected. This finding and the expression for the dependence of the selected velocity on the singular perturbation parameter and the strength of the anisotropy are found to be in complete agreement with the results of a boundary-layer model (Langer and Hong, 1986).
Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor
Branny, Artur; Kumar, Santosh; Proux, Raphaël; Gerardot, Brian D.
2017-05-01
An outstanding challenge in quantum photonics is scalability, which requires positioning of single quantum emitters in a deterministic fashion. Site positioning progress has been made in established platforms including defects in diamond and self-assembled quantum dots, albeit often with compromised coherence and optical quality. The emergence of single quantum emitters in layered transition metal dichalcogenide semiconductors offers new opportunities to construct a scalable quantum architecture. Here, using nanoscale strain engineering, we deterministically achieve a two-dimensional lattice of quantum emitters in an atomically thin semiconductor. We create point-like strain perturbations in mono- and bi-layer WSe2 which locally modify the band-gap, leading to efficient funnelling of excitons towards isolated strain-tuned quantum emitters that exhibit high-purity single photon emission. We achieve near unity emitter creation probability and a mean positioning accuracy of 120+/-32 nm, which may be improved with further optimization of the nanopillar dimensions.
Effect of pulse propagation on the two-dimensional photon echo spectrum of multilevel systems
Keusters, Dorine; Warren, Warren S.
2003-08-01
The effect of pulse propagation on the two-dimensional photon echo (2DPE) spectrum of multilevel systems is investigated using a perturbative method. At high optical densities (OD) peak profiles are broadened asymmetrically, in most cases more strongly along the ω2 direction than along the ω1 direction. The amount of broadening is determined both by the OD and by the dynamics of the system. In addition, especially if the different transitions in the system are of unequal strength, the relative intensity of the peaks changes with OD. But even if the transition strengths are the same, the behavior of the cross peaks is different from the diagonal peaks. Since peak shape and relative intensity are important parameters in the interpretation of 2DPE spectra, such OD effects should be taken into account.
Pairing in the two-dimensional Hubbard model: An exact diagonalization study
Lin, H. Q.; Hirsch, J. E.; Scalapino, D. J.
1988-05-01
We have studied the pair susceptibilities for all possible pair wave functions that fit on a two-dimensional (2D) eight-site Hubbard cluster by exact diagonalization of the Hamiltonian. Band fillings corresponding to four and six electrons were studied (two or four holes in the half-filled band) for a wide range of Hubbard interaction strengths and temperatures. Our results show that all pairing susceptibilities are suppressed by the Hubbard repulsion. We have also carried out perturbation-theory calculations which show that the leading-order U2 contributions to the d-wave pair susceptibility suppresses d-wave pairing over a significant temperature range. These results are consistent with recent Monte Carlo results and provide further evidence suggesting that the 2D Hubbard model does not exhibit superconductivity.
Energy Technology Data Exchange (ETDEWEB)
Eaton, R.R.; Hopkins, P.L.
1992-08-01
LLUVIA-II is a program designed for the efficient solution of two- dimensional transient flow of liquid water through partially saturated, porous media. The code solves Richards equation using the method-of-lines procedure. This document describes the solution procedure employed, input data structure, output, and code verification.
Crompton, Helen; LaFrance, Jason; van 't Hooft, Mark
2012-01-01
A QR (quick-response) code is a two-dimensional scannable code, similar in function to a traditional bar code that one might find on a product at the supermarket. The main difference between the two is that, while a traditional bar code can hold a maximum of only 20 digits, a QR code can hold up to 7,089 characters, so it can contain much more…
Nonlinear acoustic propagation in two-dimensional ducts
Nayfeh, A. H.; Tsai, M.-S.
1974-01-01
The method of multiple scales is used to obtain a second-order uniformly valid expansion for the nonlinear acoustic wave propagation in a two-dimensional duct whose walls are treated with a nonlinear acoustic material. The wave propagation in the duct is characterized by the unsteady nonlinear Euler equations. The results show that nonlinear effects tend to flatten and broaden the absorption versus frequency curve, in qualitative agreement with the experimental observations. Moreover, the effect of the gas nonlinearity increases with increasing sound frequency, whereas the effect of the material nonlinearity decreases with increasing sound frequency.
Two-dimensional dispersive shock waves in dissipative optical media
Kartashov, Yaroslav V
2013-01-01
We study generation of two-dimensional dispersive shock waves and oblique dark solitons upon interaction of tilted plane waves with negative refractive index defects embedded into defocusing material with linear gain and two-photon absorption. Different evolution regimes are encountered including the formation of well-localized disturbances for input tilts below critical one, and generation of extended shock waves containing multiple intensity oscillations in the "upstream" region and gradually vanishing oblique dark solitons in "downstream" region for input tilts exceeding critical one. The generation of stable dispersive shock waves is possible only below certain critical defect strength.
Three-dimensional versus two-dimensional vision in laparoscopy
DEFF Research Database (Denmark)
Sørensen, Stine Maya Dreier; Savran, Mona M; Konge, Lars;
2016-01-01
BACKGROUND: Laparoscopic surgery is widely used, and results in accelerated patient recovery time and hospital stay were compared with laparotomy. However, laparoscopic surgery is more challenging compared with open surgery, in part because surgeons must operate in a three-dimensional (3D) space...... through a two-dimensional (2D) projection on a monitor, which results in loss of depth perception. To counter this problem, 3D imaging for laparoscopy was developed. A systematic review of the literature was performed to assess the effect of 3D laparoscopy. METHODS: A systematic search of the literature...
The Rare Two-Dimensional Materials with Dirac Cones
Wang, Jinying; Deng, Shibin; Liu, Zhongfan; Liu, Zhirong
2014-01-01
Inspired by the great development of graphene, more and more works have been conducted to seek new two-dimensional (2D) materials with Dirac cones. Although 2D Dirac materials possess many novel properties and physics, they are rare compared with the numerous 2D materials. To provide explanation for the rarity of 2D Dirac materials as well as clues in searching for new Dirac systems, here we review the recent theoretical aspects of various 2D Dirac materials, including graphene, silicene, ger...
Magnetic reconnection in two-dimensional magnetohydrodynamic turbulence.
Servidio, S; Matthaeus, W H; Shay, M A; Cassak, P A; Dmitruk, P
2009-03-20
Systematic analysis of numerical simulations of two-dimensional magnetohydrodynamic turbulence reveals the presence of a large number of X-type neutral points where magnetic reconnection occurs. We examine the statistical properties of this ensemble of reconnection events that are spontaneously generated by turbulence. The associated reconnection rates are distributed over a wide range of values and scales with the geometry of the diffusion region. Locally, these events can be described through a variant of the Sweet-Parker model, in which the parameters are externally controlled by turbulence. This new perspective on reconnection is relevant in space and astrophysical contexts, where plasma is generally in a fully turbulent regime.
Logarithmic divergent thermal conductivity in two-dimensional nonlinear lattices.
Wang, Lei; Hu, Bambi; Li, Baowen
2012-10-01
Heat conduction in three two-dimensional (2D) momentum-conserving nonlinear lattices are numerically calculated via both nonequilibrium heat-bath and equilibrium Green-Kubo algorithms. It is expected by mainstream theories that heat conduction in such 2D lattices is divergent and the thermal conductivity κ increases with lattice length N logarithmically. Our simulations for the purely quartic lattice firmly confirm it. However, very robust finite-size effects are observed in the calculations for the other two lattices, which well explain some existing studies and imply the extreme difficulties in observing their true asymptotic behaviors with affordable computation resources.
Two-dimensionally confined topological edge states in photonic crystals
Barik, Sabyasachi; Miyake, Hirokazu; DeGottardi, Wade; Waks, Edo; Hafezi, Mohammad
2016-11-01
We present an all-dielectric photonic crystal structure that supports two-dimensionally confined helical topological edge states. The topological properties of the system are controlled by the crystal parameters. An interface between two regions of differing band topologies gives rise to topological edge states confined in a dielectric slab that propagate around sharp corners without backscattering. Three-dimensional finite-difference time-domain calculations show these edges to be confined in the out-of-plane direction by total internal reflection. Such nanoscale photonic crystal architectures could enable strong interactions between photonic edge states and quantum emitters.
Two-Dimensionally Confined Topological Edge States in Photonic Crystals
Barik, Sabyasachi; DeGottardi, Wade; Waks, Edo; Hafezi, Mohammad
2016-01-01
We present an all-dielectric photonic crystal structure that supports two-dimensionally confined helical topological edge states. The topological properties of the system are controlled by the crystal parameters. An interface between two regions of differing band topologies gives rise to topological edge states confined in a dielectric slab that propagate around sharp corners without backscattering. Three dimensional finite-difference time-domain calculations show these edges to be confined in the out-of-plane direction by total internal reflection. Such nanoscale photonic crystal architectures could enable strong interactions between photonic edge states and quantum emitters.
Theories on Frustrated Electrons in Two-Dimensional Organic Solids
Directory of Open Access Journals (Sweden)
Chisa Hotta
2012-08-01
Full Text Available Two-dimensional quarter-filled organic solids are a promising class of materials to realize the strongly correlated insulating states called dimer Mott insulator and charge order. In their conducting layer, the molecules form anisotropic triangular lattices, harboring geometrical frustration effect, which could give rise to many interesting states of matter in the two insulators and in the metals adjacent to them. This review is concerned with the theoretical studies on such issue over the past ten years, and provides the systematic understanding on exotic metals, dielectrics, and spin liquids, which are the consequences of the competing correlation and fluctuation under frustration.
Wake-induced bending of two-dimensional plasma crystals
Energy Technology Data Exchange (ETDEWEB)
Röcker, T. B., E-mail: tbr@mpe.mpg.de; Ivlev, A. V., E-mail: ivlev@mpe.mpg.de; Zhdanov, S. K.; Morfill, G. E. [Max Planck Institute for Extraterrestrial Physics, 85741 Garching (Germany); Couëdel, L. [CNRS, Aix-Marseille-Université, Laboratoire de Physique des Interactions Ioniques et Moléculaires, UMR 7345, 13397 Marseille Cedex 20 (France)
2014-07-15
It is shown that the wake-mediated interactions between microparticles in a two-dimensional plasma crystal affect the shape of the monolayer, making it non-flat. The equilibrium shape is calculated for various distributions of the particle number density in the monolayer. For typical experimental conditions, the levitation height of particles in the center of the crystal can be noticeably smaller than at the periphery. It is suggested that the effect of wake-induced bending can be utilized in experiments, to deduce important characteristics of the interparticle interaction.
Wake-induced bending of two-dimensional plasma crystals
Röcker, T B; Zhdanov, S K; Couëdel, L; Morfill, G E
2014-01-01
It is shown that the wake-mediated interactions between microparticles in a two-dimensional plasma crystal affect the shape of the monolayer, making it non-flat. The equilibrium shape is calculated for various distributions of the particle number density in the monolayer. For typical experimental conditions, the levitation height of particles in the center of the crystal can be noticeably smaller than at the periphery. It is suggested that the effect of wake-induced bending can be utilized in experiments, to deduce important characteristics of the interparticle interaction.
Corner wetting transition in the two-dimensional Ising model
Lipowski, Adam
1998-07-01
We study the interfacial behavior of the two-dimensional Ising model at the corner of weakened bonds. Monte Carlo simulations results show that the interface is pinned to the corner at a lower temperature than a certain temperature Tcw at which it undergoes a corner wetting transition. The temperature Tcw is substantially lower than the temperature of the ordinary wetting transition with a line of weakened bonds. A solid-on-solid-like model is proposed, which provides a supplementary description of the corner wetting transition.
Dynamic Multiscaling in Two-dimensional Fluid Turbulence
Ray, Samriddhi Sankar; Perlekar, Prasad; Pandit, Rahul
2011-01-01
We obtain, by extensive direct numerical simulations, time-dependent and equal-time structure functions for the vorticity, in both quasi-Lagrangian and Eulerian frames, for the direct-cascade regime in two-dimensional fluid turbulence with air-drag-induced friction. We show that different ways of extracting time scales from these time-dependent structure functions lead to different dynamic-multiscaling exponents, which are related to equal-time multiscaling exponents by different classes of bridge relations; for a representative value of the friction we verify that, given our error bars, these bridge relations hold.
Absolute band gaps in two-dimensional graphite photonic crystal
Institute of Scientific and Technical Information of China (English)
Gaoxin Qiu(仇高新); Fanglei Lin(林芳蕾); Hua Wang(王华); Yongping Li(李永平)
2003-01-01
The off-plane propagation of electromagnetic (EM) waves in a two-dimensional (2D) graphite photoniccrystal structure was studied using transfer matrix method. Transmission spectra calculations indicatethat such a 2D structure has a common band gap from 0.202 to 0.2035 c/a for both H and E polarizationsand for all off-plane angles form 0° up to 90°. The presence of such an absolute band gap implies that 2Dgraphite photonic crystal, which is much easier and more feasible to fabricate, can exhibit some propertiesof a three-dimensional (3D) photonic crystal.
Kinetic analysis of two dimensional metallic grating Cerenkov maser
Energy Technology Data Exchange (ETDEWEB)
Zhao Ding [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China)
2011-08-15
The dispersion relation of two dimensional metallic grating Cerenkov maser has been given by using kinetic analysis, in which the influence of electron movement is directly considered without using an equivalent dielectric medium assumption. The effects of structural parameters and beam state on the interaction gain and synchronous frequency have also been investigated in detail by numerical calculations. To an illustrative case, the quantitative relations produced from varying the gap distance between electron beam and metallic grating, beam current, electron transverse to axial velocity ratio, and electron axial velocity spread have been obtained. The developed method can be used to predict the real interaction system performances.
Mean flow generation in rotating anelastic two-dimensional convection
Currie, Laura K
2016-01-01
We investigate the processes that lead to the generation of mean flows in two-dimensional anelastic convection. The simple model consists of a plane layer that is rotating about an axis inclined to gravity. The results are two-fold: firstly we numerically investigate the onset of convection in three-dimensions, paying particular attention to the role of stratification and highlight a curious symmetry. Secondly, we investigate the mechanisms that drive both zonal and meridional flows in two dimensions. We find that, in general, non-trivial Reynolds stresses can lead to systematic flows and, using statistical measures, we quantify the role of stratification in modifying the coherence of these flows.
Duality, Monodromy and Integrability of Two Dimensional String Effective Action
Das, A; Melikyan, A; Das, Ashok
2002-01-01
The monodromy matrix, ${\\hat{\\cal M}}$, is constructed for two dimensional tree level string effective action. The pole structure of ${\\hat{\\cal M}}$ is derived using its factorizability property. It is found that the monodromy matrix transforms non-trivially under the non-compact T-duality group, which leaves the effective action invariant and this can be used to construct the monodromy matrix for more complicated backgrounds starting from simpler ones. We construct, explicitly, ${\\hat{\\cal M}}$ for the exactly solvable Nappi-Witten model, both when B=0 and $B\
Homogenization of Two-Dimensional Phononic Crystals at Low Frequencies
Institute of Scientific and Technical Information of China (English)
NI Qing; CHENG Jian-Chun
2005-01-01
@@ Effective velocities of elastic waves propagating in two-dimensional phononic crystal at low frequencies are analysed theoretically, and exact analytical formulas for effective velocities of elastic waves are derived according to the method presented by Krokhin et al. [Phys. Rev. Lett. 91 (2003) 264302]. Numerical calculations for phononic crystals consisted of array of Pb cylinders embedded in epoxy show that the composites have distinct anisotropy at low filling fraction. The anisotropy increases as the filling fraction increases, while as the filling fraction closes to the limitation, the anisotropy decreases.
Electronic Transmission Properties of Two-Dimensional Quasi-Lattice
Institute of Scientific and Technical Information of China (English)
侯志林; 傅秀军; 刘有延
2002-01-01
In the framework of the tight binding model, the electronic transmission properties of two-dimensional Penrose lattices with free boundary conditions are studied using the generalized eigenfunction method (Phys. Rev. B 60(1999)13444). The electronic transmission coefficients for Penrose lattices with different sizes and widths are calculated, and the result shows strong energy dependence because of the quasiperiodic structure and quantum coherent effect. Around the Fermi level E = 0, there is an energy region with zero transmission amplitudes,which suggests that the studied systems are insulating. The spatial distributions of several typical electronic states with different transmission coefficients are plotted to display the propagation process.
Two-dimensional conformal field theory and the butterfly effect
Roberts, Daniel A
2014-01-01
We study chaotic dynamics in two-dimensional conformal field theory through out-of-time order thermal correlators of the form $\\langle W(t)VW(t)V\\rangle$. We reproduce bulk calculations similar to those of [1], by studying the large $c$ Virasoro identity block. The contribution of this block to the above correlation function begins to decrease exponentially after a delay of $\\sim t_* - \\frac{\\beta}{2\\pi}\\log \\beta^2E_w E_v$, where $t_*$ is the scrambling time $\\frac{\\beta}{2\\pi}\\log c$, and $E_w,E_v$ are the energy scales of the $W,V$ operators.
Two-Dimensional Gel Electrophoresis: A Reference Protocol.
Saia-Cereda, Veronica M; Aquino, Adriano; Guest, Paul C; Martins-de-Souza, Daniel
2017-01-01
Two-dimensional gel electrophoresis (2DE) has been a mainstay of proteomic techniques for more than four decades. It was even in use for several years before the term proteomics was actually coined in the early 1990s. Over this time, it has been used in the study of many diseases including cancer, diabetes, heart disease, and psychiatric disorders through the proteomic analysis of body fluids and tissues. This chapter presents a general protocol which can be applied in the study of biological samples such as blood serum or plasma and multiple tissues including the brain.
Basics and recent advances of two dimensional- polyacrylamide gel electrophoresis
2014-01-01
Gel- based proteomics is one of the most versatile methods for fractionating protein complexes. Among these methods, two dimensional- polyacrylamide gel electrophoresis (2-DE) represents a mainstay orthogonal approach, which is popularly used to simultaneously fractionate, identify, and quantify proteins when coupled with mass spectrometric identification or other immunological tests. Although 2-DE was first introduced more than three decades ago, several challenges and limitations to its utility still exist. This review discusses the principles of 2-DE as well as both recent methodological advances and new applications. PMID:24735559
Size-dispersity effects in two-dimensional melting.
Watanabe, Hiroshi; Yukawa, Satoshi; Ito, Nobuyasu
2005-01-01
In order to investigate the effect of size dispersity on two-dimensional melting transitions, hard-disk systems with equimolar bidispersity are studied by means of particle dynamics simulations. From the nonequilibrium relaxation behaviors of bond-orientational order parameters, we find that (i) there is a critical dispersity at which the melting transition of the hexagonal solid vanishes and (ii) the quadratic structure is metastable in a certain region of the dispersity-density parameter space. These results suggest that the dispersity not only destroys order but produces new structures under certain specific conditions.
Human muscle proteins: analysis by two-dimensional electrophoresis
Energy Technology Data Exchange (ETDEWEB)
Giometti, C.S.; Danon, M.J.; Anderson, N.G.
1983-09-01
Proteins from single frozen sections of human muscle were separated by two-dimensional gel electrophoresis and detected by fluorography or Coomassie Blue staining. The major proteins were identical in different normal muscles obtained from either sex at different ages, and in Duchenne and myotonic dystrophy samples. Congenital myopathy denervation atrophy, polymyositis, and Becker's muscular dystrophy samples, however, showed abnormal myosin light chain compositions, some with a decrease of fast-fiber myosin light chains and others with a decrease of slow-fiber light chains. These protein alterations did not correlate with any specific disease, and may be cause by generalized muscle-fiber damage.
The XY model coupled to two-dimensional quantum gravity
Baillie, C. F.; Johnston, D. A.
1992-09-01
We perform Monte Carlo simulations using the Wolff cluster algorithm of the XY model on both fixed and dynamical phi-cubed graphs (i.e. without and with coupling to two-dimensional quantum gravity). We compare the numerical results with the theoretical expectation that the phase transition remains of KT type when the XY model is coupled to gravity. We also examine whether the universality we discovered in our earlier work on various Potts models with the same value of the central charge, c, carries over to the XY model, which has c=1.
Two-dimensional chiral topological superconductivity in Shiba lattices
Li, Jian; Neupert, Titus; Wang, Zhijun; MacDonald, A. H.; Yazdani, A.; Bernevig, B. Andrei
2016-07-01
The chiral p-wave superconductor is the archetypal example of a state of matter that supports non-Abelian anyons, a highly desired type of exotic quasiparticle. With this, it is foundational for the distant goal of building a topological quantum computer. While some candidate materials for bulk chiral superconductors exist, they are subject of an ongoing debate about their actual paring state. Here we propose an alternative route to chiral superconductivity, consisting of the surface of an ordinary superconductor decorated with a two-dimensional lattice of magnetic impurities. We furthermore identify a promising experimental platform to realize this proposal.
Field analysis of two-dimensional focusing grating
Borsboom, P.P.; Frankena, H.J.
1995-01-01
The method that we have developed [P-P. Borsboom, Ph.D. dissertation (Delft University of Technology, Delft, The Netherlands); P-P. Borsboom and H. J. Frankena, J. Opt. Soc. Am. A 12, 1134–1141 (1995)] is successfully applied to a two-dimensional focusing grating coupler. The field in the focal region has been determined for symmetrical chirped gratings consisting of as many as 124 corrugations. The intensity distribution in the focal region agrees well with the approximate predictions of geo...
Field analysis of two-dimensional integrated optical gratings
Borsboom, P.-P.; Frankena, H. J.
1995-05-01
A rigorous technique to determine the field scattered by a two-dimensional rectangular grating made up of many corrugations was developed. In this method, the grating was deemed as a sequence of two types of waveguide sections, alternatingly connected by step discontinuities. A matrix was derived that described the entire rectangular grating by integrating the separate steps and waveguide sections. With the proposed technique, several configuration were analyzed. The obtained results showed good consistency with the consequences of previous studies. Furthermore, to examine the numerical stability of the proposed method, the length of the grating was increased and obtained results for a grating with 100 periods.