Unwrapped phase inversion with an exponential damping
Choi, Yun Seok
2015-07-28
Full-waveform inversion (FWI) suffers from the phase wrapping (cycle skipping) problem when the frequency of data is not low enough. Unless we obtain a good initial velocity model, the phase wrapping problem in FWI causes a result corresponding to a local minimum, usually far away from the true solution, especially at depth. Thus, we have developed an inversion algorithm based on a space-domain unwrapped phase, and we also used exponential damping to mitigate the nonlinearity associated with the reflections. We construct the 2D phase residual map, which usually contains the wrapping discontinuities, especially if the model is complex and the frequency is high. We then unwrap the phase map and remove these cycle-based jumps. However, if the phase map has several residues, the unwrapping process becomes very complicated. We apply a strong exponential damping to the wavefield to eliminate much of the residues in the phase map, thus making the unwrapping process simple. We finally invert the unwrapped phases using the back-propagation algorithm to calculate the gradient. We progressively reduce the damping factor to obtain a high-resolution image. Numerical examples determined that the unwrapped phase inversion with a strong exponential damping generated convergent long-wavelength updates without low-frequency information. This model can be used as a good starting model for a subsequent inversion with a reduced damping, eventually leading to conventional waveform inversion.
Cellular-automata method for phase unwrapping
International Nuclear Information System (INIS)
Ghiglia, D.C.; Mastin, G.A.; Romero, L.A.
1987-01-01
Research into two-dimensional phase unwrapping has uncovered interesting and troublesome inconsistencies that cause path-dependent results. Cellular automata, which are simple, discrete mathematical systems, offered promise of computation in nondirectional, parallel manner. A cellular automaton was discovered that can unwrap consistent phase data in n dimensions in a path-independent manner and can automatically accommodate noise-induced (pointlike) inconsistencies and arbitrary boundary conditions (region partitioning). For data with regional (nonpointlike) inconsistencies, no phase-unwrapping algorithm will converge, including the cellular-automata approach. However, the automata method permits more simple visualization of the regional inconsistencies. Examples of its behavior on one- and two-dimensional data are presented
Assessment of autonomous phase unwrapping of isochromatic ...
Indian Academy of Sciences (India)
An excellent summary of phase unwrapping techniques applied to ... to fully exploit the advantage of these new developments, in this paper, ..... Madhu K R, Ramesh K 2007 New boundary information encoding and auto ... Ramesh K, Mangal S K 1999 Phase-shifting calculations in 2-D photoelasticity: revisited. J. Aero-.
Iterated unscented Kalman filter for phase unwrapping of interferometric fringes.
Xie, Xianming
2016-08-22
A fresh phase unwrapping algorithm based on iterated unscented Kalman filter is proposed to estimate unambiguous unwrapped phase of interferometric fringes. This method is the result of combining an iterated unscented Kalman filter with a robust phase gradient estimator based on amended matrix pencil model, and an efficient quality-guided strategy based on heap sort. The iterated unscented Kalman filter that is one of the most robust methods under the Bayesian theorem frame in non-linear signal processing so far, is applied to perform simultaneously noise suppression and phase unwrapping of interferometric fringes for the first time, which can simplify the complexity and the difficulty of pre-filtering procedure followed by phase unwrapping procedure, and even can remove the pre-filtering procedure. The robust phase gradient estimator is used to efficiently and accurately obtain phase gradient information from interferometric fringes, which is needed for the iterated unscented Kalman filtering phase unwrapping model. The efficient quality-guided strategy is able to ensure that the proposed method fast unwraps wrapped pixels along the path from the high-quality area to the low-quality area of wrapped phase images, which can greatly improve the efficiency of phase unwrapping. Results obtained from synthetic data and real data show that the proposed method can obtain better solutions with an acceptable time consumption, with respect to some of the most used algorithms.
The Phase Transition of Higher Dimensional Charged Black Holes
International Nuclear Information System (INIS)
Li, Huaifan; Zhao, Ren; Zhang, Lichun; Guo, Xiongying
2016-01-01
We have studied phase transitions of higher dimensional charge black hole with spherical symmetry. We calculated the local energy and local temperature and find that these state parameters satisfy the first law of thermodynamics. We analyze the critical behavior of black hole thermodynamic system by taking state parameters (Q,Φ) of black hole thermodynamic system, in accordance with considering the state parameters (P,V) of van der Waals system, respectively. We obtain the critical point of black hole thermodynamic system and find that the critical point is independent of the dual independent variables we selected. This result for asymptotically flat space is consistent with that for AdS spacetime and is intrinsic property of black hole thermodynamic system.
Frequency-domain waveform inversion using the unwrapped phase
Choi, Yun Seok; Alkhalifah, Tariq Ali
2011-01-01
Phase wrapping in the frequency-domain (or cycle skipping in the time-domain) is the major cause of the local minima problem in the waveform inversion. The unwrapped phase has the potential to provide us with a robust and reliable waveform inversion
Frequency-domain waveform inversion using the unwrapped phase
Choi, Yun Seok
2011-01-01
Phase wrapping in the frequency-domain (or cycle skipping in the time-domain) is the major cause of the local minima problem in the waveform inversion. The unwrapped phase has the potential to provide us with a robust and reliable waveform inversion, with reduced local minima. We propose a waveform inversion algorithm using the unwrapped phase objective function in the frequency-domain. The unwrapped phase, or what we call the instantaneous traveltime, is given by the imaginary part of dividing the derivative of the wavefield with respect to the angular frequency by the wavefield itself. As a result, the objective function is given a traveltime-like function, which allows us to smooth it and reduce its nonlinearity. The gradient of the objective function is computed using the back-propagation algorithm based on the adjoint-state technique. We apply both our waveform inversion algorithm using the unwrapped phase and the conventional waveform inversion and show that our inversion algorithm gives better convergence to the true model than the conventional waveform inversion. © 2011 Society of Exploration Geophysicists.
Speedup of minimum discontinuity phase unwrapping algorithm with a reference phase distribution
Liu, Yihang; Han, Yu; Li, Fengjiao; Zhang, Qican
2018-06-01
In three-dimensional (3D) shape measurement based on phase analysis, the phase analysis process usually produces a wrapped phase map ranging from - π to π with some 2 π discontinuities, and thus a phase unwrapping algorithm is necessary to recover the continuous and nature phase map from which 3D height distribution can be restored. Usually, the minimum discontinuity phase unwrapping algorithm can be used to solve many different kinds of phase unwrapping problems, but its main drawback is that it requires a large amount of computations and has low efficiency in searching for the improving loop within the phase's discontinuity area. To overcome this drawback, an improvement to speedup of the minimum discontinuity phase unwrapping algorithm by using the phase distribution on reference plane is proposed. In this improved algorithm, before the minimum discontinuity phase unwrapping algorithm is carried out to unwrap phase, an integer number K was calculated from the ratio of the wrapped phase to the nature phase on a reference plane. And then the jump counts of the unwrapped phase can be reduced by adding 2K π, so the efficiency of the minimum discontinuity phase unwrapping algorithm is significantly improved. Both simulated and experimental data results verify the feasibility of the proposed improved algorithm, and both of them clearly show that the algorithm works very well and has high efficiency.
Unweighted least squares phase unwrapping by means of multigrid techniques
Pritt, Mark D.
1995-11-01
We present a multigrid algorithm for unweighted least squares phase unwrapping. This algorithm applies Gauss-Seidel relaxation schemes to solve the Poisson equation on smaller, coarser grids and transfers the intermediate results to the finer grids. This approach forms the basis of our multigrid algorithm for weighted least squares phase unwrapping, which is described in a separate paper. The key idea of our multigrid approach is to maintain the partial derivatives of the phase data in separate arrays and to correct these derivatives at the boundaries of the coarser grids. This maintains the boundary conditions necessary for rapid convergence to the correct solution. Although the multigrid algorithm is an iterative algorithm, we demonstrate that it is nearly as fast as the direct Fourier-based method. We also describe how to parallelize the algorithm for execution on a distributed-memory parallel processor computer or a network-cluster of workstations.
Efficient Phase Unwrapping Architecture for Digital Holographic Microscopy
Directory of Open Access Journals (Sweden)
Wen-Jyi Hwang
2011-09-01
Full Text Available This paper presents a novel phase unwrapping architecture for accelerating the computational speed of digital holographic microscopy (DHM. A fast Fourier transform (FFT based phase unwrapping algorithm providing a minimum squared error solution is adopted for hardware implementation because of its simplicity and robustness to noise. The proposed architecture is realized in a pipeline fashion to maximize through put of thecomputation. Moreover, the number of hardware multipliers and dividers are minimized to reduce the hardware costs. The proposed architecture is used as a custom user logic in a system on programmable chip (SOPC for physical performance measurement. Experimental results reveal that the proposed architecture is effective for expediting the computational speed while consuming low hardware resources for designing an embedded DHM system.
Weighted least squares phase unwrapping based on the wavelet transform
Chen, Jiafeng; Chen, Haiqin; Yang, Zhengang; Ren, Haixia
2007-01-01
The weighted least squares phase unwrapping algorithm is a robust and accurate method to solve phase unwrapping problem. This method usually leads to a large sparse linear equation system. Gauss-Seidel relaxation iterative method is usually used to solve this large linear equation. However, this method is not practical due to its extremely slow convergence. The multigrid method is an efficient algorithm to improve convergence rate. However, this method needs an additional weight restriction operator which is very complicated. For this reason, the multiresolution analysis method based on the wavelet transform is proposed. By applying the wavelet transform, the original system is decomposed into its coarse and fine resolution levels and an equivalent equation system with better convergence condition can be obtained. Fast convergence in separate coarse resolution levels speeds up the overall system convergence rate. The simulated experiment shows that the proposed method converges faster and provides better result than the multigrid method.
Comparison of multihardware parallel implementations for a phase unwrapping algorithm
Hernandez-Lopez, Francisco Javier; Rivera, Mariano; Salazar-Garibay, Adan; Legarda-Sáenz, Ricardo
2018-04-01
Phase unwrapping is an important problem in the areas of optical metrology, synthetic aperture radar (SAR) image analysis, and magnetic resonance imaging (MRI) analysis. These images are becoming larger in size and, particularly, the availability and need for processing of SAR and MRI data have increased significantly with the acquisition of remote sensing data and the popularization of magnetic resonators in clinical diagnosis. Therefore, it is important to develop faster and accurate phase unwrapping algorithms. We propose a parallel multigrid algorithm of a phase unwrapping method named accumulation of residual maps, which builds on a serial algorithm that consists of the minimization of a cost function; minimization achieved by means of a serial Gauss-Seidel kind algorithm. Our algorithm also optimizes the original cost function, but unlike the original work, our algorithm is a parallel Jacobi class with alternated minimizations. This strategy is known as the chessboard type, where red pixels can be updated in parallel at same iteration since they are independent. Similarly, black pixels can be updated in parallel in an alternating iteration. We present parallel implementations of our algorithm for different parallel multicore architecture such as CPU-multicore, Xeon Phi coprocessor, and Nvidia graphics processing unit. In all the cases, we obtain a superior performance of our parallel algorithm when compared with the original serial version. In addition, we present a detailed comparative performance of the developed parallel versions.
Tile-Based Two-Dimensional Phase Unwrapping for Digital Holography Using a Modular Framework.
Directory of Open Access Journals (Sweden)
Georgios C Antonopoulos
Full Text Available A variety of physical and biomedical imaging techniques, such as digital holography, interferometric synthetic aperture radar (InSAR, or magnetic resonance imaging (MRI enable measurement of the phase of a physical quantity additionally to its amplitude. However, the phase can commonly only be measured modulo 2π, as a so called wrapped phase map. Phase unwrapping is the process of obtaining the underlying physical phase map from the wrapped phase. Tile-based phase unwrapping algorithms operate by first tessellating the phase map, then unwrapping individual tiles, and finally merging them to a continuous phase map. They can be implemented computationally efficiently and are robust to noise. However, they are prone to failure in the presence of phase residues or erroneous unwraps of single tiles. We tried to overcome these shortcomings by creating novel tile unwrapping and merging algorithms as well as creating a framework that allows to combine them in modular fashion. To increase the robustness of the tile unwrapping step, we implemented a model-based algorithm that makes efficient use of linear algebra to unwrap individual tiles. Furthermore, we adapted an established pixel-based unwrapping algorithm to create a quality guided tile merger. These original algorithms as well as previously existing ones were implemented in a modular phase unwrapping C++ framework. By examining different combinations of unwrapping and merging algorithms we compared our method to existing approaches. We could show that the appropriate choice of unwrapping and merging algorithms can significantly improve the unwrapped result in the presence of phase residues and noise. Beyond that, our modular framework allows for efficient design and test of new tile-based phase unwrapping algorithms. The software developed in this study is freely available.
Tile-Based Two-Dimensional Phase Unwrapping for Digital Holography Using a Modular Framework.
Antonopoulos, Georgios C; Steltner, Benjamin; Heisterkamp, Alexander; Ripken, Tammo; Meyer, Heiko
2015-01-01
A variety of physical and biomedical imaging techniques, such as digital holography, interferometric synthetic aperture radar (InSAR), or magnetic resonance imaging (MRI) enable measurement of the phase of a physical quantity additionally to its amplitude. However, the phase can commonly only be measured modulo 2π, as a so called wrapped phase map. Phase unwrapping is the process of obtaining the underlying physical phase map from the wrapped phase. Tile-based phase unwrapping algorithms operate by first tessellating the phase map, then unwrapping individual tiles, and finally merging them to a continuous phase map. They can be implemented computationally efficiently and are robust to noise. However, they are prone to failure in the presence of phase residues or erroneous unwraps of single tiles. We tried to overcome these shortcomings by creating novel tile unwrapping and merging algorithms as well as creating a framework that allows to combine them in modular fashion. To increase the robustness of the tile unwrapping step, we implemented a model-based algorithm that makes efficient use of linear algebra to unwrap individual tiles. Furthermore, we adapted an established pixel-based unwrapping algorithm to create a quality guided tile merger. These original algorithms as well as previously existing ones were implemented in a modular phase unwrapping C++ framework. By examining different combinations of unwrapping and merging algorithms we compared our method to existing approaches. We could show that the appropriate choice of unwrapping and merging algorithms can significantly improve the unwrapped result in the presence of phase residues and noise. Beyond that, our modular framework allows for efficient design and test of new tile-based phase unwrapping algorithms. The software developed in this study is freely available.
Linear programming phase unwrapping for dual-wavelength digital holography.
Wang, Zhaomin; Jiao, Jiannan; Qu, Weijuan; Yang, Fang; Li, Hongru; Tian, Ailing; Asundi, Anand
2017-01-20
A linear programming phase unwrapping method in dual-wavelength digital holography is proposed and verified experimentally. The proposed method uses the square of height difference as a convergence standard and theoretically gives the boundary condition in a searching process. A simulation was performed by unwrapping step structures at different levels of Gaussian noise. As a result, our method is capable of recovering the discontinuities accurately. It is robust and straightforward. In the experiment, a microelectromechanical systems sample and a cylindrical lens were measured separately. The testing results were in good agreement with true values. Moreover, the proposed method is applicable not only in digital holography but also in other dual-wavelength interferometric techniques.
Unwrapped phase inversion with an exponential damping
Choi, Yun Seok; Alkhalifah, Tariq Ali
2015-01-01
Full-waveform inversion (FWI) suffers from the phase wrapping (cycle skipping) problem when the frequency of data is not low enough. Unless we obtain a good initial velocity model, the phase wrapping problem in FWI causes a result corresponding to a
Global approaches and local strategies for phase unwrapping
International Nuclear Information System (INIS)
Guerriero, L.; Refice, A.; Stramaglia, S.; Chiaradia, M. T.; Satalino, G.; Veneziani, N.; Blonda, P.; Pasquariello, G.
2001-01-01
Phase unwrapping, i.e. the retrieval of absolute phases from wrapped, noisy measures, is a tough problem because of the presence of rotational inconsistencies (residues), randomly generated by noise and undersampling on the principal phase gradient field. These inconsistencies prevent the recovery of the absolute phase field by direct integration of the wrapped gradients. In this paper it is examined the relative merit of known global approaches and then it is presented evidence that the approach based on stochastic annealing can recover the true phase field also in noisy areas with severe undersampling, where other methods fail. Then, some experiments with local approaches are presented. A fast neural filter has been trained to eliminate close residue couples by joining them in a way which takes into account the local phase information. Performances are about 60-70% of the residues. Finally, other experiments have been aimed at designing an automated method for the determination of weight matrices to use in conjunction with local phase unwrapping algorithms. The method, tested with the minimum cost flow algorithm, gives good performances over both simulated and real data
A Parallel Computational Model for Multichannel Phase Unwrapping Problem
Imperatore, Pasquale; Pepe, Antonio; Lanari, Riccardo
2015-05-01
In this paper, a parallel model for the solution of the computationally intensive multichannel phase unwrapping (MCh-PhU) problem is proposed. Firstly, the Extended Minimum Cost Flow (EMCF) algorithm for solving MCh-PhU problem is revised within the rigorous mathematical framework of the discrete calculus ; thus permitting to capture its topological structure in terms of meaningful discrete differential operators. Secondly, emphasis is placed on those methodological and practical aspects, which lead to a parallel reformulation of the EMCF algorithm. Thus, a novel dual-level parallel computational model, in which the parallelism is hierarchically implemented at two different (i.e., process and thread) levels, is presented. The validity of our approach has been demonstrated through a series of experiments that have revealed a significant speedup. Therefore, the attained high-performance prototype is suitable for the solution of large-scale phase unwrapping problems in reasonable time frames, with a significant impact on the systematic exploitation of the existing, and rapidly growing, large archives of SAR data.
Phase unwrapping in digital holography based on non-subsampled contourlet transform
Zhang, Xiaolei; Zhang, Xiangchao; Xu, Min; Zhang, Hao; Jiang, Xiangqian
2018-01-01
In the digital holographic measurement of complex surfaces, phase unwrapping is a critical step for accurate reconstruction. The phases of the complex amplitudes calculated from interferometric holograms are disturbed by speckle noise, thus reliable unwrapping results are difficult to be obtained. Most of existing unwrapping algorithms implement denoising operations first to obtain noise-free phases and then conduct phase unwrapping pixel by pixel. This approach is sensitive to spikes and prone to unreliable results in practice. In this paper, a robust unwrapping algorithm based on the non-subsampled contourlet transform (NSCT) is developed. The multiscale and directional decomposition of NSCT enhances the boundary between adjacent phase levels and henceforth the influence of local noise can be eliminated in the transform domain. The wrapped phase map is segmented into several regions corresponding to different phase levels. Finally, an unwrapped phase map is obtained by elevating the phases of a whole segment instead of individual pixels to avoid unwrapping errors caused by local spikes. This algorithm is suitable for dealing with complex and noisy wavefronts. Its universality and superiority in the digital holographic interferometry have been demonstrated by both numerical analysis and practical experiments.
International Nuclear Information System (INIS)
Zhang, Chunwei; Zhao, Hong; Gu, Feifei; Ma, Yueyang
2015-01-01
A phase unwrapping algorithm specially designed for the phase-shifting fringe projection profilometry (FPP) is proposed. It combines a revised dual-frequency fringe projectionalgorithm and a proposed fringe background based quality guided phase unwrapping algorithm (FB-QGPUA). Phase demodulated from the high-frequency fringe patterns is partially unwrapped by that demodulated from the low-frequency ones. Then FB-QGPUA is adopted to further unwrap the partially unwrapped phase. Influences of the phase error on the measurement are researched. Strategy to select the fringe pitch is given. Experiments demonstrate that the proposed method is very robust and efficient. (paper)
Fringe-period selection for a multifrequency fringe-projection phase unwrapping method
International Nuclear Information System (INIS)
Zhang, Chunwei; Zhao, Hong; Jiang, Kejian
2016-01-01
The multi-frequency fringe-projection phase unwrapping method (MFPPUM) is a typical phase unwrapping algorithm for fringe projection profilometry. It has the advantage of being capable of correctly accomplishing phase unwrapping even in the presence of surface discontinuities. If the fringe frequency ratio of the MFPPUM is too large, fringe order error (FOE) may be triggered. FOE will result in phase unwrapping error. It is preferable for the phase unwrapping to be kept correct while the fewest sets of lower frequency fringe patterns are used. To achieve this goal, in this paper a parameter called fringe order inaccuracy (FOI) is defined, dominant factors which may induce FOE are theoretically analyzed, a method to optimally select the fringe periods for the MFPPUM is proposed with the aid of FOI, and experiments are conducted to research the impact of the dominant factors in phase unwrapping and demonstrate the validity of the proposed method. Some novel phenomena are revealed by these experiments. The proposed method helps to optimally select the fringe periods and detect the phase unwrapping error for the MFPPUM. (paper)
Two-dimensional unwrapped phase inversion with damping and a Gaussian filter
Choi, Yun Seok; Alkhalifah, Tariq Ali
2014-01-01
Phase wrapping is one of main causes of the local minima problem in waveform inversion. However, the unwrapping process for 2D phase maps that includes singular points (residues) is complicated and does not guarantee unique solutions. We employ an exponential damping to eliminate the residues in the 2D phase maps, which makes the 2D phase unwrapping process easy and produce a unique solution. A recursive inversion process using the damped unwrapped phase provides an opportunity to invert for smooth background updates first, and higher resolution updates later as we reduce the damping. We also apply a Gaussian filter to the gradient to mitigate the edge artifacts resulting from the narrow shape of the sensitivity kernels at high damping. Numerical examples demonstrate that our unwrapped phase inversion with damping and a Gaussian filter produces good convergent results even for a 3Hz single frequency of Marmousi dataset and with a starting model far from the true model.
Fast phase processing in off-axis holography by CUDA including parallel phase unwrapping.
Backoach, Ohad; Kariv, Saar; Girshovitz, Pinhas; Shaked, Natan T
2016-02-22
We present parallel processing implementation for rapid extraction of the quantitative phase maps from off-axis holograms on the Graphics Processing Unit (GPU) of the computer using computer unified device architecture (CUDA) programming. To obtain efficient implementation, we parallelized both the wrapped phase map extraction algorithm and the two-dimensional phase unwrapping algorithm. In contrast to previous implementations, we utilized unweighted least squares phase unwrapping algorithm that better suits parallelism. We compared the proposed algorithm run times on the CPU and the GPU of the computer for various sizes of off-axis holograms. Using the GPU implementation, we extracted the unwrapped phase maps from the recorded off-axis holograms at 35 frames per second (fps) for 4 mega pixel holograms, and at 129 fps for 1 mega pixel holograms, which presents the fastest processing framerates obtained so far, to the best of our knowledge. We then used common-path off-axis interferometric imaging to quantitatively capture the phase maps of a micro-organism with rapid flagellum movements.
Ensemble of hybrid genetic algorithm for two-dimensional phase unwrapping
Balakrishnan, D.; Quan, C.; Tay, C. J.
2013-06-01
The phase unwrapping is the final and trickiest step in any phase retrieval technique. Phase unwrapping by artificial intelligence methods (optimization algorithms) such as hybrid genetic algorithm, reverse simulated annealing, particle swarm optimization, minimum cost matching showed better results than conventional phase unwrapping methods. In this paper, Ensemble of hybrid genetic algorithm with parallel populations is proposed to solve the branch-cut phase unwrapping problem. In a single populated hybrid genetic algorithm, the selection, cross-over and mutation operators are applied to obtain new population in every generation. The parameters and choice of operators will affect the performance of the hybrid genetic algorithm. The ensemble of hybrid genetic algorithm will facilitate to have different parameters set and different choice of operators simultaneously. Each population will use different set of parameters and the offspring of each population will compete against the offspring of all other populations, which use different set of parameters. The effectiveness of proposed algorithm is demonstrated by phase unwrapping examples and advantages of the proposed method are discussed.
Phase-unwrapping algorithm by a rounding-least-squares approach
Juarez-Salazar, Rigoberto; Robledo-Sanchez, Carlos; Guerrero-Sanchez, Fermin
2014-02-01
A simple and efficient phase-unwrapping algorithm based on a rounding procedure and a global least-squares minimization is proposed. Instead of processing the gradient of the wrapped phase, this algorithm operates over the gradient of the phase jumps by a robust and noniterative scheme. Thus, the residue-spreading and over-smoothing effects are reduced. The algorithm's performance is compared with four well-known phase-unwrapping methods: minimum cost network flow (MCNF), fast Fourier transform (FFT), quality-guided, and branch-cut. A computer simulation and experimental results show that the proposed algorithm reaches a high-accuracy level than the MCNF method by a low-computing time similar to the FFT phase-unwrapping method. Moreover, since the proposed algorithm is simple, fast, and user-free, it could be used in metrological interferometric and fringe-projection automatic real-time applications.
Energy Technology Data Exchange (ETDEWEB)
Li, Hui-Ling [University of Electronic Science and Technology of China, School of Physical Electronics, Chengdu (China); Shenyang Normal University, College of Physics Science and Technology, Shenyang (China); Feng, Zhong-Wen [China West Normal University, College of Physics and Space Science, Nanchong (China); Zu, Xiao-Tao [University of Electronic Science and Technology of China, School of Physical Electronics, Chengdu (China)
2018-01-15
With motivation by holography, employing black hole entropy, two-point connection function and entanglement entropy, we show that, for the higher-dimensional Anti-de Sitter charged hairy black hole in the fixed charged ensemble, a Van der Waals-like phase transition can be observed. Furthermore, based on the Maxwell equal-area construction, we check numerically the equal-area law for a first order phase transition in order to further characterize the Van der Waals-like phase transition. (orig.)
International Nuclear Information System (INIS)
Li, Hui-Ling; Feng, Zhong-Wen; Zu, Xiao-Tao
2018-01-01
With motivation by holography, employing black hole entropy, two-point connection function and entanglement entropy, we show that, for the higher-dimensional Anti-de Sitter charged hairy black hole in the fixed charged ensemble, a Van der Waals-like phase transition can be observed. Furthermore, based on the Maxwell equal-area construction, we check numerically the equal-area law for a first order phase transition in order to further characterize the Van der Waals-like phase transition. (orig.)
Application of the unwrapped phase inversion to land data without source estimation
Choi, Yun Seok
2015-08-19
Unwrapped phase inversion with a strong damping was developed to solve the phase wrapping problem in frequency-domain waveform inversion. In this study, we apply the unwrapped phase inversion to band-limited real land data, for which the available minimum frequency is quite high. An important issue of the data is a strong ambiguity of source-ignition time (or source shift) shown in a seismogram. A source-estimation approach does not fully address the issue of source shift, since the velocity model and the source wavelet are updated simultaneously and interact with each other. We suggest a source-independent unwrapped phase inversion approach instead of relying on source-estimation from this land data. In the source-independent approach, the phase of the modeled data converges not to the exact phase value of the observed data, but to the relative phase value (or the trend of phases); thus it has the potential to solve the ambiguity of source-ignition time in a seismogram and work better than the source-estimation approach. Numerical examples show the validation of the source-independent unwrapped phase inversion, especially for land field data having an ambiguity in the source-ignition time.
Choi, Yun Seok; Alkhalifah, Tariq Ali; Saragiotis, Christos
2011-01-01
an approach based on unwrapping the phase. We unwrap the phase by taking the derivative of the Fourier-transformed wavefield with respect to the angular frequency and isolate its amplitude component. To do so, we first apply a damping function to the seismic
Application of the unwrapped phase inversion to land data without source estimation
Choi, Yun Seok; Alkhalifah, Tariq Ali; DeVault, Bryan
2015-01-01
and the source wavelet are updated simultaneously and interact with each other. We suggest a source-independent unwrapped phase inversion approach instead of relying on source-estimation from this land data. In the source-independent approach, the phase
Phase unwrapping algorithm using polynomial phase approximation and linear Kalman filter.
Kulkarni, Rishikesh; Rastogi, Pramod
2018-02-01
A noise-robust phase unwrapping algorithm is proposed based on state space analysis and polynomial phase approximation using wrapped phase measurement. The true phase is approximated as a two-dimensional first order polynomial function within a small sized window around each pixel. The estimates of polynomial coefficients provide the measurement of phase and local fringe frequencies. A state space representation of spatial phase evolution and the wrapped phase measurement is considered with the state vector consisting of polynomial coefficients as its elements. Instead of using the traditional nonlinear Kalman filter for the purpose of state estimation, we propose to use the linear Kalman filter operating directly with the wrapped phase measurement. The adaptive window width is selected at each pixel based on the local fringe density to strike a balance between the computation time and the noise robustness. In order to retrieve the unwrapped phase, either a line-scanning approach or a quality guided strategy of pixel selection is used depending on the underlying continuous or discontinuous phase distribution, respectively. Simulation and experimental results are provided to demonstrate the applicability of the proposed method.
Multi-frequency Phase Unwrap from Noisy Data: Adaptive Least Squares Approach
Katkovnik, Vladimir; Bioucas-Dias, José
2010-04-01
Multiple frequency interferometry is, basically, a phase acquisition strategy aimed at reducing or eliminating the ambiguity of the wrapped phase observations or, equivalently, reducing or eliminating the fringe ambiguity order. In multiple frequency interferometry, the phase measurements are acquired at different frequencies (or wavelengths) and recorded using the corresponding sensors (measurement channels). Assuming that the absolute phase to be reconstructed is piece-wise smooth, we use a nonparametric regression technique for the phase reconstruction. The nonparametric estimates are derived from a local least squares criterion, which, when applied to the multifrequency data, yields denoised (filtered) phase estimates with extended ambiguity (periodized), compared with the phase ambiguities inherent to each measurement frequency. The filtering algorithm is based on local polynomial (LPA) approximation for design of nonlinear filters (estimators) and adaptation of these filters to unknown smoothness of the spatially varying absolute phase [9]. For phase unwrapping, from filtered periodized data, we apply the recently introduced robust (in the sense of discontinuity preserving) PUMA unwrapping algorithm [1]. Simulations give evidence that the proposed algorithm yields state-of-the-art performance for continuous as well as for discontinues phase surfaces, enabling phase unwrapping in extraordinary difficult situations when all other algorithms fail.
Wrapped and unwrapped phase of radiation scattered by a discrete number of particles
International Nuclear Information System (INIS)
Watson, Stephen M; Ridley, Kevin D
2007-01-01
This paper investigates wrapped and unwrapped phase differences generated by a non-Gaussian scattering model: the two-dimensional random walk. Mean square values for these quantities are obtained for one and two scatterers, as well as the large scatterer limit when the field constitutes a circular complex Gaussian process. Numerical simulation is used to investigate the phase under more general fluctuation conditions, and reveals that the wrapped phase difference correlation converges rapidly to that result predicted for a Gaussian speckle field. Analytical results for the unwrapped phase indicate that this quantity transitions from a stationary process for one and two scatterers to a non-stationary process in the large scatterer limit. The nature of this transition is examined using numerical simulation for arbitrary scatterer number. Phase correlations are of consequence in various phase sensitive detection systems, and this paper examines both Gaussian and non-Gaussian fields
Fringe order error in multifrequency fringe projection phase unwrapping: reason and correction.
Zhang, Chunwei; Zhao, Hong; Zhang, Lu
2015-11-10
A multifrequency fringe projection phase unwrapping algorithm (MFPPUA) is important to fringe projection profilometry, especially when a discontinuous object is measured. However, a fringe order error (FOE) may occur when MFPPUA is adopted. An FOE will result in error to the unwrapped phase. Although this kind of phase error does not spread, it brings error to the eventual 3D measurement results. Therefore, an FOE or its adverse influence should be obviated. In this paper, reasons for the occurrence of an FOE are theoretically analyzed and experimentally explored. Methods to correct the phase error caused by an FOE are proposed. Experimental results demonstrate that the proposed methods are valid in eliminating the adverse influence of an FOE.
Research Note: Full-waveform inversion of the unwrapped phase of a model
Alkhalifah, Tariq Ali
2013-12-06
Reflections in seismic data induce serious non-linearity in the objective function of full- waveform inversion. Thus, without a good initial velocity model that can produce reflections within a half cycle of the frequency used in the inversion, convergence to a solution becomes difficult. As a result, we tend to invert for refracted events and damp reflections in data. Reflection induced non-linearity stems from cycle skipping between the imprint of the true model in observed data and the predicted model in synthesized data. Inverting for the phase of the model allows us to address this problem by avoiding the source of non-linearity, the phase wrapping phenomena. Most of the information related to the location (or depths) of interfaces is embedded in the phase component of a model, mainly influenced by the background model, while the velocity-contrast information (responsible for the reflection energy) is mainly embedded in the amplitude component. In combination with unwrapping the phase of data, which mitigates the non-linearity introduced by the source function, I develop a framework to invert for the unwrapped phase of a model, represented by the instantaneous depth, using the unwrapped phase of the data. The resulting gradient function provides a mechanism to non-linearly update the velocity model by applying mainly phase shifts to the model. In using the instantaneous depth as a model parameter, we keep track of the model properties unfazed by the wrapping phenomena. © 2013 European Association of Geoscientists & Engineers.
Traveltime sensitivity kernels for wave equation tomography using the unwrapped phase
Djebbi, Ramzi
2014-02-18
Wave equation tomography attempts to improve on traveltime tomography, by better adhering to the requirements of our finite-frequency data. Conventional wave equation tomography, based on the first-order Born approximation followed by cross-correlation traveltime lag measurement, or on the Rytov approximation for the phase, yields the popular hollow banana sensitivity kernel indicating that the measured traveltime at a point is insensitive to perturbations along the ray theoretical path at certain finite frequencies. Using the instantaneous traveltime, which is able to unwrap the phase of the signal, instead of the cross-correlation lag, we derive new finite-frequency traveltime sensitivity kernels. The kernel reflects more the model-data dependency, we typically encounter in full waveform inversion. This result confirms that the hollow banana shape is borne of the cross-correlation lag measurement, which exposes the Born approximations weakness in representing transmitted waves. The instantaneous traveltime can thus mitigate the additional component of nonlinearity introduced by the hollow banana sensitivity kernels in finite-frequency traveltime tomography. The instantaneous traveltime simply represents the unwrapped phase of Rytov approximation, and thus is a good alternative to Born and Rytov to compute the misfit function for wave equation tomography. We show the limitations of the cross-correlation associated with Born approximation for traveltime lag measurement when the source signatures of the measured and modelled data are different. The instantaneous traveltime is proven to be less sensitive to the distortions in the data signature. The unwrapped phase full banana shape of the sensitivity kernels shows smoother update compared to the banana–doughnut kernels. The measurement of the traveltime delay caused by a small spherical anomaly, embedded into a 3-D homogeneous model, supports the full banana sensitivity assertion for the unwrapped phase.
Traveltime sensitivity kernels for wave equation tomography using the unwrapped phase
Djebbi, Ramzi; Alkhalifah, Tariq Ali
2014-01-01
Wave equation tomography attempts to improve on traveltime tomography, by better adhering to the requirements of our finite-frequency data. Conventional wave equation tomography, based on the first-order Born approximation followed by cross-correlation traveltime lag measurement, or on the Rytov approximation for the phase, yields the popular hollow banana sensitivity kernel indicating that the measured traveltime at a point is insensitive to perturbations along the ray theoretical path at certain finite frequencies. Using the instantaneous traveltime, which is able to unwrap the phase of the signal, instead of the cross-correlation lag, we derive new finite-frequency traveltime sensitivity kernels. The kernel reflects more the model-data dependency, we typically encounter in full waveform inversion. This result confirms that the hollow banana shape is borne of the cross-correlation lag measurement, which exposes the Born approximations weakness in representing transmitted waves. The instantaneous traveltime can thus mitigate the additional component of nonlinearity introduced by the hollow banana sensitivity kernels in finite-frequency traveltime tomography. The instantaneous traveltime simply represents the unwrapped phase of Rytov approximation, and thus is a good alternative to Born and Rytov to compute the misfit function for wave equation tomography. We show the limitations of the cross-correlation associated with Born approximation for traveltime lag measurement when the source signatures of the measured and modelled data are different. The instantaneous traveltime is proven to be less sensitive to the distortions in the data signature. The unwrapped phase full banana shape of the sensitivity kernels shows smoother update compared to the banana–doughnut kernels. The measurement of the traveltime delay caused by a small spherical anomaly, embedded into a 3-D homogeneous model, supports the full banana sensitivity assertion for the unwrapped phase.
Alkhalifah, Tariq Ali
2012-09-25
Traveltime inversion focuses on the geometrical features of the waveform (traveltimes), which is generally smooth, and thus, tends to provide averaged (smoothed) information of the model. On other hand, general waveform inversion uses additional elements of the wavefield including amplitudes to extract higher resolution information, but this comes at the cost of introducing non-linearity to the inversion operator, complicating the convergence process. We use unwrapped phase-based objective functions in waveform inversion as a link between the two general types of inversions in a domain in which such contributions to the inversion process can be easily identified and controlled. The instantaneous traveltime is a measure of the average traveltime of the energy in a trace as a function of frequency. It unwraps the phase of wavefields yielding far less non-linearity in the objective function than that experienced with conventional wavefields, yet it still holds most of the critical wavefield information in its frequency dependency. However, it suffers from non-linearity introduced by the model (or reflectivity), as reflections from independent events in our model interact with each other. Unwrapping the phase of such a model can mitigate this non-linearity as well. Specifically, a simple modification to the inverted domain (or model), can reduce the effect of the model-induced non-linearity and, thus, make the inversion more convergent. Simple numerical examples demonstrate these assertions.
Alkhalifah, Tariq Ali; Choi, Yun Seok
2012-01-01
Traveltime inversion focuses on the geometrical features of the waveform (traveltimes), which is generally smooth, and thus, tends to provide averaged (smoothed) information of the model. On other hand, general waveform inversion uses additional elements of the wavefield including amplitudes to extract higher resolution information, but this comes at the cost of introducing non-linearity to the inversion operator, complicating the convergence process. We use unwrapped phase-based objective functions in waveform inversion as a link between the two general types of inversions in a domain in which such contributions to the inversion process can be easily identified and controlled. The instantaneous traveltime is a measure of the average traveltime of the energy in a trace as a function of frequency. It unwraps the phase of wavefields yielding far less non-linearity in the objective function than that experienced with conventional wavefields, yet it still holds most of the critical wavefield information in its frequency dependency. However, it suffers from non-linearity introduced by the model (or reflectivity), as reflections from independent events in our model interact with each other. Unwrapping the phase of such a model can mitigate this non-linearity as well. Specifically, a simple modification to the inverted domain (or model), can reduce the effect of the model-induced non-linearity and, thus, make the inversion more convergent. Simple numerical examples demonstrate these assertions.
Use of (N-1)-D expansions for N-D phase unwrapping in MRI
Bones, Philip J.; King, Laura J.; Millane, Rick P.
2017-09-01
In MRI the presence of metal implants causes severe artifacts in images and interferes with the usual techniques used to separate fat signals from other tissues. In the Dixon method, three images are acquired at different echo times to enable the variation in the magnetic field to be estimated. However, the estimate is represented as the phase of a complex quantity and therefore suffers from wrapping. High field gradients near the metal mean that the phase estimate is undersampled and therefore challenging to unwrap. We have developed POP, phase estimation by onion peeling, an algorithm which unwraps the phase along 1-D paths for a 2-D image obtained with the Dixon method. The unwrapping is initially performed along a closed path enclosing the implant and well separated from it. The recovered phase is expanded using a smooth periodic basis along the path. Then, path-by-path, the estimate is applied to the next path and then the expansion coefficients are estimated to best fit the wrapped measurements. We have successfully tested POP on MRI images of specially constructed phantoms and on a group of patients with hip implants. In principle, POP can be extended to 3-D imaging. In that case, POP would entail representing phase with a suitably smooth basis over a series of surfaces enclosing the implant (the "onion skins"), again beginning the phase estimation well away from the implant. An approach for this is proposed. Results are presented for fat and water separation for 2-D images of phantoms and actual patients. The practicality of the method and its employment in clinical MRI are discussed.
Unwrapped phase inversion for near surface seismic data
Choi, Yun Seok; Alkhalifah, Tariq Ali
2012-01-01
The Phase-wrapping is one of the main obstacles of waveform inversion. We use an inversion algorithm based on the instantaneous-traveltime that overcomes the phase-wrapping problem. With a high damping factor, the frequency-dependent instantaneous
Li, Xiangyu; Huang, Zhanhua; Zhu, Meng; He, Jin; Zhang, Hao
2014-12-01
Hilbert transform (HT) is widely used in temporal speckle pattern interferometry, but errors from low modulations might propagate and corrupt the calculated phase. A spatio-temporal method for phase retrieval using temporal HT and spatial phase unwrapping is presented. In time domain, the wrapped phase difference between the initial and current states is directly determined by using HT. To avoid the influence of the low modulation intensity, the phase information between the two states is ignored. As a result, the phase unwrapping is shifted from time domain to space domain. A phase unwrapping algorithm based on discrete cosine transform is adopted by taking advantage of the information in adjacent pixels. An experiment is carried out with a Michelson-type interferometer to study the out-of-plane deformation field. High quality whole-field phase distribution maps with different fringe densities are obtained. Under the experimental conditions, the maximum number of fringes resolvable in a 416×416 frame is 30, which indicates a 15λ deformation along the direction of loading.
Unwrapped phase inversion for near surface seismic data
Choi, Yun Seok
2012-11-04
The Phase-wrapping is one of the main obstacles of waveform inversion. We use an inversion algorithm based on the instantaneous-traveltime that overcomes the phase-wrapping problem. With a high damping factor, the frequency-dependent instantaneous-traveltime inversion provides the stability of refraction tomography, with higher resolution results, and no arrival picking involved. We apply the instantaneous-traveltime inversion to the synthetic data generated by the elastic time-domain modeling. The synthetic data is a representative of the near surface seismic data. Although the inversion algorithm is based on the acoustic wave equation, the numerical examples show that the instantaneous-traveltime inversion generates a convergent velocity model, very similar to what we see from traveltime tomography.
Reentrant phase transitions of higher-dimensional AdS black holes in dRGT massive gravity
International Nuclear Information System (INIS)
Zou, De-Cheng; Yue, Ruihong; Zhang, Ming
2017-01-01
We study the P-V criticality and phase transition in the extended phase space of anti-de Sitter (AdS) black holes in higher-dimensional de Rham, Gabadadze and Tolley (dRGT) massive gravity, treating the cosmological constant as pressure and the corresponding conjugate quantity is interpreted as thermodynamic volume. Besides the usual small/large black hole phase transitions, the interesting thermodynamic phenomena of reentrant phase transitions (RPTs) are observed for black holes in all d ≥ 6-dimensional spacetime when the coupling coefficients c_im"2 of massive potential satisfy some certain conditions. (orig.)
Reentrant phase transitions of higher-dimensional AdS black holes in dRGT massive gravity
Energy Technology Data Exchange (ETDEWEB)
Zou, De-Cheng; Yue, Ruihong [Yangzhou University, College of Physical Science and Technology, Yangzhou (China); Zhang, Ming [Xi' an Aeronautical University, Faculty of Science, Xi' an (China)
2017-04-15
We study the P-V criticality and phase transition in the extended phase space of anti-de Sitter (AdS) black holes in higher-dimensional de Rham, Gabadadze and Tolley (dRGT) massive gravity, treating the cosmological constant as pressure and the corresponding conjugate quantity is interpreted as thermodynamic volume. Besides the usual small/large black hole phase transitions, the interesting thermodynamic phenomena of reentrant phase transitions (RPTs) are observed for black holes in all d ≥ 6-dimensional spacetime when the coupling coefficients c{sub i}m{sup 2} of massive potential satisfy some certain conditions. (orig.)
Li, Sikun; Wang, Xiangzhao; Su, Xianyu; Tang, Feng
2012-04-20
This paper theoretically discusses modulus of two-dimensional (2D) wavelet transform (WT) coefficients, calculated by using two frequently used 2D daughter wavelet definitions, in an optical fringe pattern analysis. The discussion shows that neither is good enough to represent the reliability of the phase data. The differences between the two frequently used 2D daughter wavelet definitions in the performance of 2D WT also are discussed. We propose a new 2D daughter wavelet definition for reliability-guided phase unwrapping of optical fringe pattern. The modulus of the advanced 2D WT coefficients, obtained by using a daughter wavelet under this new daughter wavelet definition, includes not only modulation information but also local frequency information of the deformed fringe pattern. Therefore, it can be treated as a good parameter that represents the reliability of the retrieved phase data. Computer simulation and experimentation show the validity of the proposed method.
Directory of Open Access Journals (Sweden)
Wanli Liu
2015-07-01
Full Text Available Differential interferometric synthetic aperture radar has been shown to be effective for monitoring subsidence in coal mining areas. Phase unwrapping can have a dramatic influence on the monitoring result. In this paper, a filtering-based phase unwrapping algorithm in combination with path-following is introduced to unwrap differential interferograms with high noise in mining areas. It can perform simultaneous noise filtering and phase unwrapping so that the pre-filtering steps can be omitted, thus usually retaining more details and improving the detectable deformation. For the method, the nonlinear measurement model of phase unwrapping is processed using a simplified Cubature Kalman filtering, which is an effective and efficient tool used in many nonlinear fields. Three case studies are designed to evaluate the performance of the method. In Case 1, two tests are designed to evaluate the performance of the method under different factors including the number of multi-looks and path-guiding indexes. The result demonstrates that the unwrapped results are sensitive to the number of multi-looks and that the Fisher Distance is the most suitable path-guiding index for our study. Two case studies are then designed to evaluate the feasibility of the proposed phase unwrapping method based on Cubature Kalman filtering. The results indicate that, compared with the popular Minimum Cost Flow method, the Cubature Kalman filtering-based phase unwrapping can achieve promising results without pre-filtering and is an appropriate method for coal mining areas with high noise.
It is only a banana-Traveltime sensitivity kernels using the unwrapped phase
Djebbi, Ramzi; Alkhalifah, Tariq Ali
2012-01-01
Traveltime sensitivity kernels for finite-frequency traveltimes computed using the Born or Rytov approximations admits hallow banana shaped responses in the plane of propagation and a circular doughnut shaped responses in the cross section. This suggests that finite-frequency traveltimes are insensitive to velocity information along the infinite-frequency ray path, which is obviously inaccurate and creates a disconnect in the traveltime dependency on frequency. Using the instantaneous traveltime of the wavefield, which is capable of unwrapping the phase function, we obtain traveltime sensitivity kernels that have plain banana shape responses, with the thickness of the banana governed by the investigated frequency. This result confirms that the hallow banana shape is simply a result of the wrapping of the phase of the wavefield, in which Born nor Rytov approximations can properly deal with. The instantaneous traveltime can, thus, mitigate the nonlinearity problem encountered in finite-frequency traveltime inversions that may arise from these hallow banana sensitivity kernels.
Li, Yuanbo; Cui, Xiaoqian; Wang, Hongbei; Zhao, Mengge; Ding, Hongbin
2017-10-01
Digital speckle pattern interferometry (DSPI) can diagnose the topography evolution in real-time, continuous and non-destructive, and has been considered as a most promising technique for Plasma-Facing Components (PFCs) topography diagnostic under the complicated environment of tokamak. It is important for the study of digital speckle pattern interferometry to enhance speckle patterns and obtain the real topography of the ablated crater. In this paper, two kinds of numerical model based on flood-fill algorithm has been developed to obtain the real profile by unwrapping from the wrapped phase in speckle interference pattern, which can be calculated through four intensity images by means of 4-step phase-shifting technique. During the process of phase unwrapping by means of flood-fill algorithm, since the existence of noise pollution, and other inevitable factors will lead to poor quality of the reconstruction results, this will have an impact on the authenticity of the restored topography. The calculation of the quality parameters was introduced to obtain the quality-map from the wrapped phase map, this work presents two different methods to calculate the quality parameters. Then quality parameters are used to guide the path of flood-fill algorithm, and the pixels with good quality parameters are given priority calculation, so that the quality of speckle interference pattern reconstruction results are improved. According to the comparison between the flood-fill algorithm which is suitable for speckle pattern interferometry and the quality-guided flood-fill algorithm (with two different calculation approaches), the errors which caused by noise pollution and the discontinuous of the strips were successfully reduced.
Zhang, Minliang; Chen, Qian; Tao, Tianyang; Feng, Shijie; Hu, Yan; Li, Hui; Zuo, Chao
2017-08-21
Temporal phase unwrapping (TPU) is an essential algorithm in fringe projection profilometry (FPP), especially when measuring complex objects with discontinuities and isolated surfaces. Among others, the multi-frequency TPU has been proven to be the most reliable algorithm in the presence of noise. For a practical FPP system, in order to achieve an accurate, efficient, and reliable measurement, one needs to make wise choices about three key experimental parameters: the highest fringe frequency, the phase-shifting steps, and the fringe pattern sequence. However, there was very little research on how to optimize these parameters quantitatively, especially considering all three aspects from a theoretical and analytical perspective simultaneously. In this work, we propose a new scheme to determine simultaneously the optimal fringe frequency, phase-shifting steps and pattern sequence under multi-frequency TPU, robustly achieving high accuracy measurement by a minimum number of fringe frames. Firstly, noise models regarding phase-shifting algorithms as well as 3-D coordinates are established under a projector defocusing condition, which leads to the optimal highest fringe frequency for a FPP system. Then, a new concept termed frequency-to-frame ratio (FFR) that evaluates the magnitude of the contribution of each frame for TPU is defined, on which an optimal phase-shifting combination scheme is proposed. Finally, a judgment criterion is established, which can be used to judge whether the ratio between adjacent fringe frequencies is conducive to stably and efficiently unwrapping the phase. The proposed method provides a simple and effective theoretical framework to improve the accuracy, efficiency, and robustness of a practical FPP system in actual measurement conditions. The correctness of the derived models as well as the validity of the proposed schemes have been verified through extensive simulations and experiments. Based on a normal monocular 3-D FPP hardware system
The phase structure of higher-dimensional black rings and black holes
International Nuclear Information System (INIS)
Emparan, Roberto; Harmark, Troels; Niarchos, Vasilis; Obers, Niels A.; RodrIguez, Maria J.
2007-01-01
We construct an approximate solution for an asymptotically flat, neutral, thin rotating black ring in any dimension D ≥ 5 by matching the near-horizon solution for a bent boosted black string, to a linearized gravity solution away from the horizon. The rotating black ring solution has a regular horizon of topology S 1 x S D-3 and incorporates the balancing condition of the ring as a zero-tension condition. For D = 5 our method reproduces the thin ring limit of the exact black ring solution. For D ≥ 6 we show that the black ring has a higher entropy than the Myers-Perry black hole in the ultra-spinning regime. By exploiting the correspondence between ultra-spinning black holes and black membranes on a two-torus, we take steps towards qualitatively completing the phase diagram of rotating blackfolds with a single angular momentum. We are led to propose a connection between MP black holes and black rings, and between MP black holes and black Saturns, through merger transitions involving two kinds of 'pinched' black holes. More generally, the analogy suggests an infinite number of pinched black holes of spherical topology leading to a complicated pattern of connections and mergers between phases
Choi, Yun Seok
2011-01-01
First-arrival picking has long suffered from cycle skipping, especially when the first arrival is contaminated with noise or have experienced complex near surface phenomena. We propose a new algorithm for automatic picking of first arrivals using an approach based on unwrapping the phase. We unwrap the phase by taking the derivative of the Fourier-transformed wavefield with respect to the angular frequency and isolate its amplitude component. To do so, we first apply a damping function to the seismic trace, calculate the derivative of the wavefield with respect to the angular frequency, divide the derivative of wavefield by the wavefield itself, and finally take its imaginary part. We compare our derivative approach to the logarithmic one and show that the derivative approach does not suffer from the phase wrapping or cycle-skipping effects. Numerical examples show that our automatic picking algorithm gives convergent and reliable results for the noise-free synthetic data and noisy field data. © 2011 Society of Exploration Geophysicists.
Energy Technology Data Exchange (ETDEWEB)
Li, Huai-Fan; Zhao, Hui-Hua; Zhang, Li-Chun; Zhao, Ren [Shanxi Datong University, Institute of Theoretical Physics, Datong (China); Shanxi Datong University, Department of Physics, Datong (China)
2017-05-15
Using Maxwell's equal area law, we discuss the phase transition of higher dimensional charged topological dilaton AdS black hole with a nonlinear source. The coexisting region of the two phases is found and we depict the coexistence region in the P-v diagrams. The two-phase equilibrium curves in the P-T diagrams are plotted, and we take the first order approximation of volume v in the calculation. To better compare with a general thermodynamic system, the Clapeyron equation is derived for a higher dimensional charged topological black hole with a nonlinear source. The latent heat of an isothermal phase transition is investigated. We also study the effect of the parameters of the black hole on the region of two-phase coexistence. The results show that the black hole may go through a small-large phase transition similar to those of usual non-gravity thermodynamic systems. (orig.)
Refraction traveltime tomography with irregular topography using the unwrapped phase inversion
Choi, Yun Seok; Alkhalifah, Tariq Ali
2013-01-01
inversion zones and ray shadow regions. We develop a tomographic approach based on traveltime solutions obtained by tracking the phase (instantaneous traveltime) of the wavefield solution of the Helmholtz wave equation. Since the instantaneous
Dong, Jingtao; Lu, Rongsheng
2018-04-30
The simultaneous determination of t, n(λ), and κ(λ) of thin films can be a tough task for the high correlation of fit parameters. The strong assumptions about the type of dispersion relation are commonly used as a consequence to alleviate correlation concerns by reducing the free parameters before the nonlinear regression analysis. Here we present an angle-resolved spectral reflectometry for the simultaneous determination of weakly absorbing thin film parameters, where a reflectance interferogram is recorded in both angular and spectral domains in a single-shot measurement for the point of the sample being illuminated. The variations of the phase recovered from the interferogram as functions of t, n, and κ reveals that the unwrapped phase is monotonically related to t, n, and κ, thereby allowing the problem of correlation to be alleviated by multiple linear regression. After removing the 2π ambiguity of the unwrapped phase, the merit function based on the absolute unwrapped phase performs a 3D data cube with variables of t, n and κ at each wavelength. The unique solution of t, n, and κ can then be directly determined from the extremum of the 3D data cube at each wavelength with no need of dispersion relation. A sample of GaN thin film grown on a polished sapphire substrate is tested. The experimental data of t and [n(λ), κ(λ)] are confirmed by the scanning electron microscopy and the comparison with the results of other related works, respectively. The consistency of the results shows the proposed method provides a useful tool for the determination of the thickness and optical constants of weakly absorbing thin films.
Refraction traveltime tomography with irregular topography using the unwrapped phase inversion
Choi, Yun Seok
2013-01-01
Traveltime tomography has long served as a stable and efficient tool for velocity estimation, especially for the near surface. It, however, suffers from some of limitations associated with ray tracing and high-frequency traveltime in velocity inversion zones and ray shadow regions. We develop a tomographic approach based on traveltime solutions obtained by tracking the phase (instantaneous traveltime) of the wavefield solution of the Helmholtz wave equation. Since the instantaneous-traveltime does not suffer from phase wrapping, the inversion algorithm using the instantaneous-traveltime has the potential to generate robust inversion results. With a high damping factor, the instantaneous-traveltime inversion provides refraction tomography similar results, but from a single frequency. Despite the Helmholtz-based solver implementation, the tomographic inversion handles irrgular topography. The numerical examples show that our inversion algorithm generates a convergent smooth velocity model, which looks very much like a tomographic result. Next, we plan to apply the instantaneous-traveltime inversion algorithm to real seismic data acquired from the near surface with irregular topography.
Wave equation tomography using the unwrapped phase - Analysis of the traveltime sensitivity kernels
Djebbi, Ramzi
2013-01-01
Full waveform inversion suffers from the high non-linearity in the misfit function, which causes the convergence to a local minimum. In the other hand, traveltime tomography has a quasi-linear misfit function but yields low- resolution models. Wave equation tomography (WET) tries to improve on traveltime tomography, by better adhering to the requirements of our finite-frequency data. However, conventional (WET), based on the crosscorelaion lag, yields the popular hallow banana sensitivity kernel indicating that the measured wavefield at a point is insensitive to perturbations along the ray theoretical path at certain finite frequencies. Using the instantaneous traveltime, the sensitivity kernel reflects more the model-data dependency we grown accustom to in seismic inversion (even phase inversion). Demonstrations on synthetic and the Mamousi model support such assertions.
Higher dimensional loop quantum cosmology
International Nuclear Information System (INIS)
Zhang, Xiangdong
2016-01-01
Loop quantum cosmology (LQC) is the symmetric sector of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogeneous cosmological model in n + 1 dimensions is quantized by the loop quantization method. Interestingly, we find that the underlying quantum theories are divided into two qualitatively different sectors according to spacetime dimensions. The effective Hamiltonian and modified dynamical equations of n + 1 dimensional LQC are obtained. Moreover, our results indicate that the classical big bang singularity is resolved in arbitrary spacetime dimensions by a quantum bounce. We also briefly discuss the similarities and differences between the n + 1 dimensional model and the 3 + 1 dimensional one. Our model serves as a first example of higher dimensional loop quantum cosmology and offers the possibility to investigate quantum gravity effects in higher dimensional cosmology. (orig.)
Photogrammetric fingerprint unwrapping
Paar, Gerhard; del Pilar Caballo Perucha, Maria; Bauer, Arnold; Nauschnegg, Bernhard
2008-04-01
Fingerprints are important biometric cues. Compared to conventional fingerprint sensors the use of contact-free stereoscopic image acquisition of the front-most finger segment has a set of advantages: Finger deformation is avoided, the entire relevant area for biometric use is covered, some technical aspects like sensor maintenance and cleaning are facilitated, and access to a three-dimensional reconstruction of the covered area is possible. We describe a photogrammetric workflow for nail-to-nail fingerprint reconstruction: A calibrated sensor setup with typically 5 cameras and dedicated illumination acquires adjacent stereo pairs. Using the silhouettes of the segmented finger a raw cylindrical model is generated. After preprocessing (shading correction, dust removal, lens distortion correction), each individual camera texture is projected onto the model. Image-to-image matching on these pseudo ortho images and dense 3D reconstruction obtains a textured cylindrical digital surface model with radial distances around the major axis and a grid size in the range of 25-50 µm. The model allows for objective fingerprint unwrapping and novel fingerprint matching algorithms since 3D relations between fingerprint features are available as additional cues. Moreover, covering the entire region with relevant fingerprint texture is particularly important for establishing a comprehensive forensic database. The workflow has been implemented in portable C and is ready for industrial exploitation. Further improvement issues are code optimization, unwrapping method, illumination strategy to avoid highlights and to improve the initial segmentation, and the comparison of the unwrapping result to conventional fingerprint acquisition technology.
Extended inflation from higher dimensional theories
International Nuclear Information System (INIS)
Holman, R.; Kolb, E.W.; Vadas, S.L.; Wang, Yun.
1990-04-01
The possibility is considered that higher dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. Two separate models are analayzed. One is a very simple toy model consisting of higher dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of non-trivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a non-trivial potential for the radius of the internal space. It was found that extended inflation does not occur in these models. It was also found that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation
Extended inflation from higher-dimensional theories
International Nuclear Information System (INIS)
Holman, R.; Kolb, E.W.; Vadas, S.L.; Wang, Y.
1991-01-01
We consider the possibility that higher-dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. We analyze two separate models. One is a very simple toy model consisting of higher-dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of nontrivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a nontrivial potential for the radius of the internal space. We find that extended inflation does not occur in these models. We also find that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation
Instabilities of higher dimensional compactifications
International Nuclear Information System (INIS)
Accetta, F.S.
1987-02-01
Various schemes for cosmological compactification of higher dimensional theories are considered. Possible instabilities which drive the ground state with static internal space to de Sitter-like expansion of all dimensions are discussed. These instabilities are due to semiclassical barrier penetration and classical thermal fluctuations. For the case of the ten dimensional Chapline-Manton action, it is possible to avoid such difficulties by balancing one-loop Casimir corrections against monopole contributions from the field strength H/sub MNP/ and fermionic condensates. 10 refs
Gravastars with higher dimensional spacetimes
Ghosh, Shounak; Ray, Saibal; Rahaman, Farook; Guha, B. K.
2018-07-01
We present a new model of gravastar in the higher dimensional Einsteinian spacetime including Einstein's cosmological constant Λ. Following Mazur and Mottola (2001, 2004) we design the star with three specific regions, as follows: (I) Interior region, (II) Intermediate thin spherical shell and (III) Exterior region. The pressure within the interior region is equal to the negative matter density which provides a repulsive force over the shell. This thin shell is formed by ultra relativistic plasma, where the pressure is directly proportional to the matter-energy density which does counter balance the repulsive force from the interior whereas the exterior region is completely vacuum assumed to be de Sitter spacetime which can be described by the generalized Schwarzschild solution. With this specification we find out a set of exact non-singular and stable solutions of the gravastar which seems physically very interesting and reasonable.
Higher dimensional discrete Cheeger inequalities
Directory of Open Access Journals (Sweden)
Anna Gundert
2015-01-01
Full Text Available For graphs there exists a strong connection between spectral and combinatorial expansion properties. This is expressed, e.g., by the discrete Cheeger inequality, the lower bound of which states that $\\lambda(G \\leq h(G$, where $\\lambda(G$ is the second smallest eigenvalue of the Laplacian of a graph $G$ and $h(G$ is the Cheeger constant measuring the edge expansion of $G$. We are interested in generalizations of expansion properties to finite simplicial complexes of higher dimension (or uniform hypergraphs. Whereas higher dimensional Laplacians were introduced already in 1945 by Eckmann, the generalization of edge expansion to simplicial complexes is not straightforward. Recently, a topologically motivated notion analogous to edge expansion that is based on $\\mathbb{Z}_2$-cohomology was introduced by Gromov and independently by Linial, Meshulam and Wallach. It is known that for this generalization there is no direct higher dimensional analogue of the lower bound of the Cheeger inequality. A different, combinatorially motivated generalization of the Cheeger constant, denoted by $h(X$, was studied by Parzanchevski, Rosenthal and Tessler. They showed that indeed $\\lambda(X \\leq h(X$, where $\\lambda(X$ is the smallest non-trivial eigenvalue of the ($(k-1$-dimensional upper Laplacian, for the case of $k$-dimensional simplicial complexes $X$ with complete $(k-1$-skeleton. Whether this inequality also holds for $k$-dimensional complexes with non-com\\-plete$(k-1$-skeleton has been an open question.We give two proofs of the inequality for arbitrary complexes. The proofs differ strongly in the methods and structures employed,and each allows for a different kind of additional strengthening of the original result.
Tavakkoli Estahbanat, A.; Dehghani, M.
2017-09-01
In interferometry technique, phases have been modulated between 0-2π. Finding the number of integer phases missed when they were wrapped is the main goal of unwrapping algorithms. Although the density of points in conventional interferometry is high, this is not effective in some cases such as large temporal baselines or noisy interferograms. Due to existing noisy pixels, not only it does not improve results, but also it leads to some unwrapping errors during interferogram unwrapping. In PS technique, because of the sparse PS pixels, scientists are confronted with a problem to unwrap phases. Due to the irregular data separation, conventional methods are sterile. Unwrapping techniques are divided in to path-independent and path-dependent in the case of unwrapping paths. A region-growing method which is a path-dependent technique has been used to unwrap PS data. In this paper an idea of EKF has been generalized on PS data. This algorithm is applied to consider the nonlinearity of PS unwrapping problem as well as conventional unwrapping problem. A pulse-pair method enhanced with singular value decomposition (SVD) has been used to estimate spectral shift from interferometric power spectral density in 7*7 local windows. Furthermore, a hybrid cost-map is used to manage the unwrapping path. This algorithm has been implemented on simulated PS data. To form a sparse dataset, A few points from regular grid are randomly selected and the RMSE of results and true unambiguous phases in presented to validate presented approach. The results of this algorithm and true unwrapped phases were completely identical.
Higher dimensional homogeneous cosmology in Lyra geometry
Indian Academy of Sciences (India)
1Department of Mathematics, Jadavpur University, Kolkata 700 032, India. 2Khodar ... 1. Introduction. The idea of higher dimensional theory was originated in super string and super gravity .... Equation (7) can easily be integrated to obtain.
Execution spaces for simple higher dimensional automata
DEFF Research Database (Denmark)
Raussen, Martin
2012-01-01
Higher dimensional automata (HDA) are highly expressive models for concurrency in Computer Science, cf van Glabbeek (Theor Comput Sci 368(1–2): 168–194, 2006). For a topologist, they are attractive since they can be modeled as cubical complexes—with an inbuilt restriction for directions of allowa......Higher dimensional automata (HDA) are highly expressive models for concurrency in Computer Science, cf van Glabbeek (Theor Comput Sci 368(1–2): 168–194, 2006). For a topologist, they are attractive since they can be modeled as cubical complexes—with an inbuilt restriction for directions...
Execution spaces for simple higher dimensional automata
DEFF Research Database (Denmark)
Raussen, Martin
Higher Dimensional Automata (HDA) are highly expressive models for concurrency in Computer Science, cf van Glabbeek [26]. For a topologist, they are attractive since they can be modeled as cubical complexes - with an inbuilt restriction for directions´of allowable (d-)paths. In Raussen [25], we...
Isoclinic Ambiguity Unwrapping of Circular Ring under Diametric Compression
Directory of Open Access Journals (Sweden)
Huang M.-J.
2010-06-01
Full Text Available Isoclinic and isochromatic parameters in photoelastic analysis are formulated by arc tangent function of several phase shifting frames but for isochromatic calculation it is, in addition, in terms of isoclinic data also. Thus, any isoclinic phase ambiguity would also result in the phase inconsistencies of isochromatic calculation and cause unwrapping problems and difficulties. Many methods had been proposed to treat these kinds of isochromatic fringes but lots of treatments were needed for the correct retrieval. In this work, the isoclinic ambiguity problem is investigated and solved directly by a novel regional phase unwrapping technique. Once the isoclinic phase ambiguity problems are solved, a correct isoclinic result can be obtained. Then, substituting this result into the isochromatic formation yields an ambiguity free isochromatic phase map, which can be easily restored by any phase unwrapping algorithm. A stress frozen sample - circular ring under diametric compression verifies its effectiveness. Usually happened is that this kind of sample is with ambiguous isoclinic data which would cause phase ambiguities of the isochromatic formulation if not treated well first.
Thermodynamics of higher dimensional black holes
International Nuclear Information System (INIS)
Accetta, F.S.; Gleiser, M.
1986-05-01
We discuss the thermodynamics of higher dimensional black holes with particular emphasis on a new class of spinning black holes which, due to the increased number of Casimir invariants, have additional spin degrees of freedom. In suitable limits, analytic solutions in arbitrary dimensions are presented for their temperature, entropy, and specific heat. In 5 + 1 and 9 + 1 dimensions, more general forms for these quantities are given. It is shown that the specific heat for a higher dimensional black hole is negative definite if it has only one non-zero spin parameter, regardless of the value of this parameter. We also consider equilibrium configurations with both massless particles and massive string modes. 16 refs., 3 figs
Thermodynamics of higher dimensional black holes
Energy Technology Data Exchange (ETDEWEB)
Accetta, F.S.; Gleiser, M.
1986-05-01
We discuss the thermodynamics of higher dimensional black holes with particular emphasis on a new class of spinning black holes which, due to the increased number of Casimir invariants, have additional spin degrees of freedom. In suitable limits, analytic solutions in arbitrary dimensions are presented for their temperature, entropy, and specific heat. In 5 + 1 and 9 + 1 dimensions, more general forms for these quantities are given. It is shown that the specific heat for a higher dimensional black hole is negative definite if it has only one non-zero spin parameter, regardless of the value of this parameter. We also consider equilibrium configurations with both massless particles and massive string modes. 16 refs., 3 figs.
Perturbations of higher-dimensional spacetimes
Energy Technology Data Exchange (ETDEWEB)
Durkee, Mark; Reall, Harvey S, E-mail: M.N.Durkee@damtp.cam.ac.uk, E-mail: H.S.Reall@damtp.cam.ac.uk [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)
2011-02-07
We discuss linearized gravitational perturbations of higher-dimensional spacetimes. For algebraically special spacetimes (e.g. Myers-Perry black holes), we show that there exist local gauge invariant quantities linear in the metric perturbation. These are the higher-dimensional generalizations of the 4D Newman-Penrose scalars that (in an algebraically special vacuum spacetime) satisfy decoupled equations of motion. We show that decoupling occurs in more than four dimensions if, and only if, the spacetime admits a null geodesic congruence with vanishing expansion, rotation and shear. Decoupling of electromagnetic perturbations occurs under the same conditions. Although these conditions are not satisfied in black hole spacetimes, they are satisfied in the near-horizon geometry of an extreme black hole.
Spatial infinity in higher dimensional spacetimes
International Nuclear Information System (INIS)
Shiromizu, Tetsuya; Tomizawa, Shinya
2004-01-01
Motivated by recent studies on the uniqueness or nonuniqueness of higher dimensional black hole spacetime, we investigate the asymptotic structure of spatial infinity in n-dimensional spacetimes (n≥4). It turns out that the geometry of spatial infinity does not have maximal symmetry due to the nontrivial Weyl tensor (n-1) C abcd in general. We also address static spacetime and its multipole moments P a 1 a 2 ···a s . Contrasting with four dimensions, we stress that the local structure of spacetimes cannot be unique under fixed multipole moments in static vacuum spacetimes. For example, we consider the generalized Schwarzschild spacetimes which are deformed black hole spacetimes with the same multipole moments as spherical Schwarzschild black holes. To specify the local structure of the static vacuum solution we need some additional information, at least the Weyl tensor (n-2) C abcd at spatial infinity
Higher-dimensional relativistic-fluid spheres
International Nuclear Information System (INIS)
Patel, L. K.; Ahmedabad, Gujarat Univ.
1997-01-01
They consider the hydrostatic equilibrium of relativistic-fluid spheres for a D-dimensional space-time. Three physically viable interior solutions of the Einstein field equations corresponding to perfect-fluid spheres in a D-dimensional space-time are obtained. When D = 4 they reduce to the Tolman IV solution, the Mehra solution and the Finch-Skea solution. The solutions are smoothly matched with the D-dimensional Schwarzschild exterior solution at the boundary r = a of the fluid sphere. Some physical features and other related details of the solutions are briefly discussed. A brief description of two other new solutions for higher-dimensional perfect-fluid spheres is also given
Multifractal and higher-dimensional zeta functions
International Nuclear Information System (INIS)
Véhel, Jacques Lévy; Mendivil, Franklin
2011-01-01
In this paper, we generalize the zeta function for a fractal string (as in Lapidus and Frankenhuijsen 2006 Fractal Geometry, Complex Dimensions and Zeta Functions: Geometry and Spectra of Fractal Strings (New York: Springer)) in several directions. We first modify the zeta function to be associated with a sequence of covers instead of the usual definition involving gap lengths. This modified zeta function allows us to define both a multifractal zeta function and a zeta function for higher-dimensional fractal sets. In the multifractal case, the critical exponents of the zeta function ζ(q, s) yield the usual multifractal spectrum of the measure. The presence of complex poles for ζ(q, s) indicates oscillations in the continuous partition function of the measure, and thus gives more refined information about the multifractal spectrum of a measure. In the case of a self-similar set in R n , the modified zeta function yields asymptotic information about both the 'box' counting function of the set and the n-dimensional volume of the ε-dilation of the set
Moduli stabilization in higher dimensional brane models
International Nuclear Information System (INIS)
Flachi, Antonino; Pujolas, Oriol; Garriga, Jaume; Tanaka, Takahiro
2003-01-01
We consider a class of warped higher dimensional brane models with topology M x Σ x S 1 /Z 2 , where Σ is a D2 dimensional manifold. Two branes of co-dimension one are embedded in such a bulk space-time and sit at the orbifold fixed points. We concentrate on the case where an exponential warp factor (depending on the distance along the orbifold) accompanies the Minkowski M and the internal space Σ line elements. We evaluate the moduli effective potential induced by bulk scalar fields in these models, and we show that generically this can stabilize the size of the extra dimensions. As an application, we consider a scenario where supersymmetry is broken not far below the cutoff scale, and the hierarchy between the electroweak and the effective Planck scales is generated by a combination of redshift and large volume effects. The latter is efficient due to the shrinking of Σ at the negative tension brane, where matter is placed. In this case, we find that the effective potential can stabilize the size of the extra dimensions (and the hierarchy) without fine tuning, provided that the internal space Σ is flat. (author)
Moduli stabilization in higher dimensional brane models
Energy Technology Data Exchange (ETDEWEB)
Flachi, Antonino; Pujolas, Oriol [IFAE, Campus UAB, 08193 Bellaterra, Barcelona (Spain)]. E-mail: pujolas@ifae.es; Garriga, Jaume [IFAE, Campus UAB, 08193 Bellaterra, Barcelona (Spain); Departament de Fisica Fonamental and C.E.R. en Astrofisica, Fisica de Particules i Cosmologia Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Tanaka, Takahiro [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford MA 02155 (United States); Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)
2003-08-01
We consider a class of warped higher dimensional brane models with topology M x {sigma} x S{sup 1}/Z{sub 2}, where {sigma} is a D2 dimensional manifold. Two branes of co-dimension one are embedded in such a bulk space-time and sit at the orbifold fixed points. We concentrate on the case where an exponential warp factor (depending on the distance along the orbifold) accompanies the Minkowski M and the internal space {sigma} line elements. We evaluate the moduli effective potential induced by bulk scalar fields in these models, and we show that generically this can stabilize the size of the extra dimensions. As an application, we consider a scenario where supersymmetry is broken not far below the cutoff scale, and the hierarchy between the electroweak and the effective Planck scales is generated by a combination of redshift and large volume effects. The latter is efficient due to the shrinking of {sigma} at the negative tension brane, where matter is placed. In this case, we find that the effective potential can stabilize the size of the extra dimensions (and the hierarchy) without fine tuning, provided that the internal space {sigma} is flat. (author)
Higher dimensional time-energy entanglement
International Nuclear Information System (INIS)
Richart, Daniel Lampert
2014-01-01
Judging by the compelling number of innovations based on taming quantum mechanical effects, such as the development of transistors and lasers, further research in this field promises to tackle further technological challenges in the years to come. This statement gains even more importance in the information processing scenario. Here, the growing data generation and the correspondingly higher need for more efficient computational resources and secure high bandwidth networks are central problems which need to be tackled. In this sense, the required CPU minituarization makes the design of structures at atomic levels inevitable, as foreseen by Moore's law. From these perspectives, it is necessary to concentrate further research efforts into controlling and manipulating quantum mechanical systems. This enables for example to encode quantum superposition states to tackle problems which are computationally NP hard and which therefore cannot be solved efficiently by classical computers. The only limitation affecting these solutions is the low scalability of existing quantum systems. Similarly, quantum communication schemes are devised to certify the secure transmission of quantum information, but are still limited by a low transmission bandwidth. This thesis follows the guideline defined by these research projects and aims to further increase the scalability of the quantum mechanical systems required to perform these tasks. The method used here is to encode quantum states into photons generated by spontaneous parametric down-conversion (SPDC). An intrinsic limitation of photons is that the scalability of quantum information schemes employing them is limited by the low detection efficiency of commercial single photon detectors. This is addressed by encoding higher dimensional quantum states into two photons, increasing the scalability of the scheme in comparison to multi-photon states. Further on, the encoding of quantum information into the emission-time degree of
Higher dimensional time-energy entanglement
Energy Technology Data Exchange (ETDEWEB)
Richart, Daniel Lampert
2014-07-08
Judging by the compelling number of innovations based on taming quantum mechanical effects, such as the development of transistors and lasers, further research in this field promises to tackle further technological challenges in the years to come. This statement gains even more importance in the information processing scenario. Here, the growing data generation and the correspondingly higher need for more efficient computational resources and secure high bandwidth networks are central problems which need to be tackled. In this sense, the required CPU minituarization makes the design of structures at atomic levels inevitable, as foreseen by Moore's law. From these perspectives, it is necessary to concentrate further research efforts into controlling and manipulating quantum mechanical systems. This enables for example to encode quantum superposition states to tackle problems which are computationally NP hard and which therefore cannot be solved efficiently by classical computers. The only limitation affecting these solutions is the low scalability of existing quantum systems. Similarly, quantum communication schemes are devised to certify the secure transmission of quantum information, but are still limited by a low transmission bandwidth. This thesis follows the guideline defined by these research projects and aims to further increase the scalability of the quantum mechanical systems required to perform these tasks. The method used here is to encode quantum states into photons generated by spontaneous parametric down-conversion (SPDC). An intrinsic limitation of photons is that the scalability of quantum information schemes employing them is limited by the low detection efficiency of commercial single photon detectors. This is addressed by encoding higher dimensional quantum states into two photons, increasing the scalability of the scheme in comparison to multi-photon states. Further on, the encoding of quantum information into the emission-time degree of
Higher-Dimensional Solitons Stabilized by Opposite Charge
Binder, B
2002-01-01
In this paper it is shown how higher-dimensional solitons can be stabilized by a topological phase gradient, a field-induced shift in effective dimensionality. As a prototype, two instable 2-dimensional radial symmetric Sine-Gordon extensions (pulsons) are coupled by a sink/source term such, that one becomes a stable 1d and the other a 3d wave equation. The corresponding physical process is identified as a polarization that fits perfectly to preliminary considerations regarding the nature of electric charge and background of 1/137. The coupling is iterative with convergence limit and bifurcation at high charge. It is driven by the topological phase gradient or non-local Gauge potential that can be mapped to a local oscillator potential under PSL(2,R).
An approach to higher dimensional theories based on lattice gauge theory
International Nuclear Information System (INIS)
Murata, M.; So, H.
2004-01-01
A higher dimensional lattice space can be decomposed into a number of four-dimensional lattices called as layers. The higher dimensional gauge theory on the lattice can be interpreted as four-dimensional gauge theories on the multi-layer with interactions between neighboring layers. We propose the new possibility to realize the continuum limit of a five-dimensional theory based on the property of the phase diagram
Fermion tunneling from higher-dimensional black holes
International Nuclear Information System (INIS)
Lin Kai; Yang Shuzheng
2009-01-01
Via the semiclassical approximation method, we study the 1/2-spin fermion tunneling from a higher-dimensional black hole. In our work, the Dirac equations are transformed into a simple form, and then we simplify the fermion tunneling research to the study of the Hamilton-Jacobi equation in curved space-time. Finally, we get the fermion tunneling rates and the Hawking temperatures at the event horizon of higher-dimensional black holes. We study fermion tunneling of a higher-dimensional Schwarzschild black hole and a higher-dimensional spherically symmetric quintessence black hole. In fact, this method is also applicable to the study of fermion tunneling from four-dimensional or lower-dimensional black holes, and we will take the rainbow-Finsler black hole as an example in order to make the fact explicit.
Charged fluid distribution in higher dimensional spheroidal space-time
Indian Academy of Sciences (India)
A general solution of Einstein field equations corresponding to a charged fluid distribution on the background of higher dimensional spheroidal space-time is obtained. The solution generates several known solutions for superdense star having spheroidal space-time geometry.
Higher-dimensional Bianchi type-VIh cosmologies
Lorenz-Petzold, D.
1985-09-01
The higher-dimensional perfect fluid equations of a generalization of the (1 + 3)-dimensional Bianchi type-VIh space-time are discussed. Bianchi type-V and Bianchi type-III space-times are also included as special cases. It is shown that the Chodos-Detweiler (1980) mechanism of cosmological dimensional-reduction is possible in these cases.
On conformal Paneitz curvature equations in higher dimensional spheres
International Nuclear Information System (INIS)
El Mehdi, Khalil
2004-11-01
We study the problem of prescribing the Paneitz curvature on higher dimensional spheres. Particular attention is paid to the blow-up points, i.e. the critical points at infinity of the corresponding variational problem. Using topological tools and a careful analysis of the gradient flow lines in the neighborhood of such critical points at infinity, we prove some existence results. (author)
Higher dimensional global monopole in Brans–Dicke theory
Indian Academy of Sciences (India)
Keywords. Global monopole; Brans–Dicke theory; higher dimension. PACS Nos 04.20.Jb; 98.80.Bp; 04.50.+h. 1. Introduction. The idea of higher dimensional theory was originated in super string and super gravity the- ories to unify gravity with other fundamental forces in nature. Solutions of Einstein field equations in higher ...
Heeding the waveform inversion nonlinearity by unwrapping the model and data
Alkhalifah, Tariq Ali
2012-01-01
Unlike traveltime inversion, waveform inversion provides relatively higher-resolution inverted models. This feature, however, comes at the cost of introducing complex nonlinearity to the inversion operator complicating the convergence process. We use unwrapped-phase-based objective functions to reduce such nonlinearity in a domain in which the high-frequency component is given by the traveltime inversion. Such information is packaged in a frequency-dependent attribute (or traveltime) that can be easily manipulated at different frequencies. It unwraps the phase of the wavefield yielding far less nonlinearity in the objective function than those experienced with the conventional misfit objective function, and yet it still holds most of the critical waveform information in its frequency dependency. However, it suffers from nonlinearity introduced by the model (or reflectivity), as events interact with each other (something like cross talk). This stems from the sinusoidal nature of the band-limited reflectivity model. Unwrapping the phase for such a model can mitigate this nonlinearity as well. Specifically, a simple modification to the inverted domain (or model), can reduce the effect of the model-induced nonlinearity and, thus, make the inversion more convergent. Simple examples are used to highlight such features.
Higher-dimensional analogues of Donaldson-Witten theory
International Nuclear Information System (INIS)
Acharya, B.S.; Spence, B.
1997-01-01
We present a Donaldson-Witten-type field theory in eight dimensions on manifolds with Spin(7) holonomy. We prove that the stress tensor is BRST exact for metric variations preserving the holonomy and we give the invariants for this class of variations. In six and seven dimensions we propose similar theories on Calabi-Yau threefolds and manifolds of G 2 holonomy, respectively. We point out that these theories arise by considering supersymmetric Yang-Mills theory defined on such manifolds. The theories are invariant under metric variations preserving the holonomy structure without the need for twisting. This statement is a higher-dimensional analogue of the fact that Donaldson-Witten field theory on hyper-Kaehler 4-manifolds is topological without twisting. Higher-dimensional analogues of Floer cohomology are briefly outlined. All of these theories arise naturally within the context of string theory. (orig.)
Higher dimensional strange quark matter solutions in self creation cosmology
Energy Technology Data Exchange (ETDEWEB)
Şen, R., E-mail: ramazansen-1991@hotmail.com [Institute for Natural and Applied Sciences, Çanakkale Onsekiz Mart University, 17020, Çanakkale (Turkey); Aygün, S., E-mail: saygun@comu.edu.tr [Department of Physics, Art and Science Faculty, Çanakkale Onsekiz Mart University, Çanakkale 17020 (Turkey)
2016-03-25
In this study, we have generalized the higher dimensional flat Friedmann-Robertson-Walker (FRW) universe solutions for a cloud of string with perfect fluid attached strange quark matter (SQM) in Self Creation Cosmology (SCC). We have obtained that the cloud of string with perfect fluid does not survive and the string tension density vanishes for this model. However, we get dark energy model for strange quark matter with positive density and negative pressure in self creation cosmology.
Torsion and curvature in higher dimensional supergravity theories
International Nuclear Information System (INIS)
Smith, A.W.; Pontificia Univ. Catolica do Rio de Janeiro
1983-01-01
This work is an extension of Dragon's theorems to higher dimensional space-time. It is shown that the first set of Bianchi identities allow us to express the curvature components in terms of torsion components and its covariant derivatives. It is also shown that the second set of Bianchi identities does not give any new information which is not already contained in the first one. (Author) [pt
Bisimulation for Higher-Dimensional Automata. A Geometric Interpretation
DEFF Research Database (Denmark)
Fahrenberg, Ulrich
We show how parallel compostition of higher-dimensional automata (HDA) can be expressed categorically in the spirit of Winskel & Nielsen. Employing the notion of computation path introduced by van Glabbeek, we define a new notion of bisimulation of HDA using open maps. We derive a connection...... between computation paths and carrier sequences of dipaths and show that bisimilarity of HDA can be decided by the use of geometric techniques....
Electromagnetic field in higher-dimensional black-hole spacetimes
International Nuclear Information System (INIS)
Krtous, Pavel
2007-01-01
A special test electromagnetic field in the spacetime of the higher-dimensional generally rotating NUT-(anti-)de Sitter black hole is found. It is adjusted to the hidden symmetries of the background represented by the principal Killing-Yano tensor. Such an electromagnetic field generalizes the field of charged black hole in four dimensions. In higher dimensions, however, the gravitational backreaction of such a field cannot be consistently solved
Higher dimensional curved domain walls on Kähler surfaces
Energy Technology Data Exchange (ETDEWEB)
Akbar, Fiki T., E-mail: ftakbar@fi.itb.ac.id [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, 40132 (Indonesia); Gunara, Bobby E., E-mail: bobby@fi.itb.ac.id [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, 40132 (Indonesia); Radjabaycolle, Flinn C. [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, 40132 (Indonesia); Departement of Physics, Faculty of Mathematics and Natural Sciences, Cendrawasih University, Jl. Kampwolker Kampus Uncen Baru Waena-Jayapura 99351 (Indonesia); Wijaya, Rio N. [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, 40132 (Indonesia)
2017-03-15
In this paper we study some aspects of curved BPS-like domain walls in higher dimensional gravity theory coupled to scalars where the scalars span a complex Kähler surface with scalar potential turned on. Assuming that a fake superpotential has a special form which depends on Kähler potential and a holomorphic function, we prove that BPS-like equations have a local unique solution. Then, we analyze the vacuum structure of the theory including their stability using dynamical system and their existence in ultraviolet-infrared regions using renormalization group flow.
Ultraviolet divergences in higher dimensional supersymmetric Yang-Mills theories
International Nuclear Information System (INIS)
Howe, P.S.; Stelle, K.S.
1984-01-01
We determine the loop orders for the onset of allowed ultra-violet divergences in higher dimensional supersymmetric Yang-Mills theories. Cancellations are controlled by the non-renormalization theorems for the linearly realizable supersymmetries and by the requirement that counterterms display the full non-linear supersymmetries when the classical equations of motion are imposed. The first allowed divergences in the maximal super Yang-Mills theories occur at four loops in five dimensions, three loops in six dimensions and two loops in seven dimensions. (orig.)
Higher dimensional curved domain walls on Kähler surfaces
International Nuclear Information System (INIS)
Akbar, Fiki T.; Gunara, Bobby E.; Radjabaycolle, Flinn C.; Wijaya, Rio N.
2017-01-01
In this paper we study some aspects of curved BPS-like domain walls in higher dimensional gravity theory coupled to scalars where the scalars span a complex Kähler surface with scalar potential turned on. Assuming that a fake superpotential has a special form which depends on Kähler potential and a holomorphic function, we prove that BPS-like equations have a local unique solution. Then, we analyze the vacuum structure of the theory including their stability using dynamical system and their existence in ultraviolet-infrared regions using renormalization group flow.
Naked singularities in higher dimensional Vaidya space-times
International Nuclear Information System (INIS)
Ghosh, S. G.; Dadhich, Naresh
2001-01-01
We investigate the end state of the gravitational collapse of a null fluid in higher-dimensional space-times. Both naked singularities and black holes are shown to be developing as the final outcome of the collapse. The naked singularity spectrum in a collapsing Vaidya region (4D) gets covered with the increase in dimensions and hence higher dimensions favor a black hole in comparison to a naked singularity. The cosmic censorship conjecture will be fully respected for a space of infinite dimension
Accretion onto a charged higher-dimensional black hole
International Nuclear Information System (INIS)
Sharif, M.; Iftikhar, Sehrish
2016-01-01
This paper deals with the steady-state polytropic fluid accretion onto a higher-dimensional Reissner-Nordstroem black hole. We formulate the generalized mass flux conservation equation, energy flux conservation and relativistic Bernoulli equation to discuss the accretion process. The critical accretion is investigated by finding the critical radius, the critical sound velocity, and the critical flow velocity. We also explore gas compression and temperature profiles to analyze the asymptotic behavior. It is found that the results for the Schwarzschild black hole are recovered when q = 0 in four dimensions. We conclude that the accretion process in higher dimensions becomes slower in the presence of charge. (orig.)
Accretion onto a charged higher-dimensional black hole
Energy Technology Data Exchange (ETDEWEB)
Sharif, M.; Iftikhar, Sehrish [University of the Punjab, Department of Mathematics, Lahore (Pakistan)
2016-03-15
This paper deals with the steady-state polytropic fluid accretion onto a higher-dimensional Reissner-Nordstroem black hole. We formulate the generalized mass flux conservation equation, energy flux conservation and relativistic Bernoulli equation to discuss the accretion process. The critical accretion is investigated by finding the critical radius, the critical sound velocity, and the critical flow velocity. We also explore gas compression and temperature profiles to analyze the asymptotic behavior. It is found that the results for the Schwarzschild black hole are recovered when q = 0 in four dimensions. We conclude that the accretion process in higher dimensions becomes slower in the presence of charge. (orig.)
Diffusion in higher dimensional SYK model with complex fermions
Cai, Wenhe; Ge, Xian-Hui; Yang, Guo-Hong
2018-01-01
We construct a new higher dimensional SYK model with complex fermions on bipartite lattices. As an extension of the original zero-dimensional SYK model, we focus on the one-dimension case, and similar Hamiltonian can be obtained in higher dimensions. This model has a conserved U(1) fermion number Q and a conjugate chemical potential μ. We evaluate the thermal and charge diffusion constants via large q expansion at low temperature limit. The results show that the diffusivity depends on the ratio of free Majorana fermions to Majorana fermions with SYK interactions. The transport properties and the butterfly velocity are accordingly calculated at low temperature. The specific heat and the thermal conductivity are proportional to the temperature. The electrical resistivity also has a linear temperature dependence term.
Graviton emission from a higher-dimensional black hole
International Nuclear Information System (INIS)
Cornell, Alan S.; Naylor, Wade; Sasaki, Misao
2006-01-01
We discuss the graviton absorption probability (greybody factor) and the cross-section of a higher-dimensional Schwarzschild black hole (BH). We are motivated by the suggestion that a great many BHs may be produced at the LHC and bearing this fact in mind, for simplicity, we shall investigate the intermediate energy regime for a static Schwarzschild BH. That is, for (2M) 1/(n-1) ω ∼ 1, where M is the mass of the black hole and ω is the energy of the emitted gravitons in (2+n)-dimensions. To find easily tractable solutions we work in the limit l >> 1, where l is the angular momentum quantum number of the graviton
The dynamical structure of higher dimensional Chern-Simons theory
International Nuclear Information System (INIS)
Banados, M.; Garay, L.J.; Henneaux, M.
1996-01-01
Higher dimensional Chern-Simons theories, even though constructed along the same topological pattern as in 2+1 dimensions, have been shown recently to have generically a non-vanishing number of degrees of freedom. In this paper, we carry out the complete Dirac Hamiltonian analysis (separation of first and second class constraints and calculation of the Dirac bracket) for a group G x U(1). We also study the algebra of surface charges that arise in the presence of boundaries and show that it is isomorphic to the WZW 4 discussed in the literature. Some applications are then considered. It is shown, in particular, that Chern-Simons gravity in dimensions greater than or equal to five has a propagating torsion. (orig.)
Bianchi's Bäcklund transformation for higher dimensional quadrics
Dincă, Ion I.
2016-12-01
We provide a generalization of Bianchi's Bäcklund transformation from 2-dimensional quadrics to higher dimensional quadrics (which is also a generalization of Tenenblat-Terng's Bäcklund transformation of isometric deformations of Hn(R) in R 2 n - 1 to general quadrics). Our investigation is the higher dimensional version of Bianchi's main three theorems on the theory of isometric deformations of quadrics and Bianchi's treatment of the Bäcklund transformation for diagonal paraboloids via conjugate systems. It became the driving force which led to the flourishing of the classical differential geometry in the second half of the XIX th century and its profound study by illustrious geometers led to interesting results. Today it is still an open problem in its full generality, but basic familiar results like the Gauß-Bonnet fundamental theorem of surfaces and the Codazzi-Mainardi equations (independently discovered also by Peterson) were first communicated to the French Academy of Sciences. A list (most likely incomplete) of the winners of the prize includes Bianchi, Bonnet, Guichard, Weingarten.Up to 1899 isometric deformations of the (pseudo-)sphere and isotropic quadrics without center (from a metric point of view they can be considered as metrically degenerate quadrics without center) together with their Bäcklund transformation and the complementary transformation of isometric deformations of surfaces of revolution were investigated by geometers such as Bäcklund, Bianchi, Bonnet, Darboux, Goursat, Hazzidakis, Lie, Weingarten, etc.In 1899 Guichard discovered that when quadrics with(out) center and of revolution around the focal axis roll on their isometric deformations their foci describe constant mean curvature (minimal) surfaces (and Bianchi proved the converse: all constant mean curvature (minimal) surfaces can be realized in this way).With Guichard's result the race to find the isometric deformations of general quadrics was on; it ended with Bianchi
Exact coefficients for higher dimensional operators with sixteen supersymmetries
Energy Technology Data Exchange (ETDEWEB)
Chen, Wei-Ming [Department of Physics and Astronomy, National Taiwan University,Taipei 10617, Taiwan, R.O.C. (China); Huang, Yu-tin [Department of Physics and Astronomy, National Taiwan University,Taipei 10617, Taiwan, R.O.C. (China); School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Wen, Congkao [INFN Sezione di Roma “Tor Vergata' ,Via della Ricerca Scientifica, 00133 Roma (Italy)
2015-09-15
We consider constraints on higher-dimensional operators for supersymmetric effective field theories. In four dimensions with maximal supersymmetry and SU(4) R-symmetry, we demonstrate that the coefficients of abelian operators F{sup n} with MHV helicity configurations must satisfy a recursion relation, and are completely determined by that of F{sup 4}. As the F{sup 4} coefficient is known to be one-loop exact, this allows us to derive exact coefficients for all such operators. We also argue that the results are consistent with the SL(2,Z) duality symmetry. Breaking SU(4) to Sp(4), in anticipation for the Coulomb branch effective action, we again find an infinite class of operators whose coefficients are determined exactly. We also consider three-dimensional N=8 as well as six-dimensional N=(2,0),(1,0) and (1,1) theories. In all cases, we demonstrate that the coefficient of dimension-six operator must be proportional to the square of that of dimension-four.
The Higgs particle and higher-dimensional theories
International Nuclear Information System (INIS)
Lim, C. S.
2014-01-01
In spite of the great success of LHC experiments, we do not know whether the discovered “standard model-like” Higgs particle is really what the standard model predicts, or a particle that some new physics has in its low-energy effective theory. Also, the long-standing problems concerning the property of the Higgs and its interactions are still there, and we still do not have any conclusive argument on the origin of the Higgs itself. In this article we focus on higher-dimensional theories as new physics. First we give a brief review of their representative scenarios and closely related 4D scenarios. Among them, we mainly discuss two interesting possibilities of the origin of the Higgs: the Higgs as a gauge boson and the Higgs as a (pseudo) Nambu–Goldstone boson. Next, we argue that theories of new physics are divided into two categories, i.e., theories with normal Higgs interactions and those with anomalous Higgs interactions. Interestingly, both the candidates for the origin of the Higgs mentioned above predict characteristic “anomalous” Higgs interactions, such as the deviation of the Yukawa couplings from the standard model predictions. Such deviations can hopefully be investigated by precision tests of Higgs interactions at the planned ILC experiment. Also discussed is the main decay mode of the Higgs, H→γγ. Again, theories belonging to different categories are known to predict remarkably different new physics contributions to this important process
Possibility of higher-dimensional anisotropic compact star
International Nuclear Information System (INIS)
Bhar, Piyali; Rahaman, Farook; Ray, Saibal; Chatterjee, Vikram
2015-01-01
We provide a new class of interior solutions for anisotropic stars admitting conformal motion in higher-dimensional noncommutative spacetime. The Einstein field equations are solved by choosing a particular density distribution function of Lorentzian type as provided by Nazari and Mehdipour [1, 2] under a noncommutative geometry. Several cases with 4 and higher dimensions, e.g. 5, 6, and 11 dimensions, are discussed separately. An overall observation is that the model parameters, such as density, radial pressure, transverse pressure, and anisotropy, all are well behaved and represent a compact star with mass 2.27 M s un and radius 4.17 km. However, emphasis is put on the acceptability of the model from a physical point of view. As a consequence it is observed that higher dimensions, i.e. beyond 4D spacetime, exhibit several interesting yet bizarre features, which are not at all untenable for a compact stellar model of strange quark type; thus this dictates the possibility of its extra-dimensional existence. (orig.)
Possibility of higher-dimensional anisotropic compact star
Energy Technology Data Exchange (ETDEWEB)
Bhar, Piyali; Rahaman, Farook [Jadavpur University, Department of Mathematics, Kolkata, West Bengal (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Chatterjee, Vikram [Central Footwear Training Centre, Department of Physics, Parganas, West Bengal (India)
2015-05-15
We provide a new class of interior solutions for anisotropic stars admitting conformal motion in higher-dimensional noncommutative spacetime. The Einstein field equations are solved by choosing a particular density distribution function of Lorentzian type as provided by Nazari and Mehdipour [1, 2] under a noncommutative geometry. Several cases with 4 and higher dimensions, e.g. 5, 6, and 11 dimensions, are discussed separately. An overall observation is that the model parameters, such as density, radial pressure, transverse pressure, and anisotropy, all are well behaved and represent a compact star with mass 2.27 M{sub s}un and radius 4.17 km. However, emphasis is put on the acceptability of the model from a physical point of view. As a consequence it is observed that higher dimensions, i.e. beyond 4D spacetime, exhibit several interesting yet bizarre features, which are not at all untenable for a compact stellar model of strange quark type; thus this dictates the possibility of its extra-dimensional existence. (orig.)
Stationary strings near a higher-dimensional rotating black hole
International Nuclear Information System (INIS)
Frolov, Valeri P.; Stevens, Kory A.
2004-01-01
We study stationary string configurations in a space-time of a higher-dimensional rotating black hole. We demonstrate that the Nambu-Goto equations for a stationary string in the 5D (five-dimensional) Myers-Perry metric allow a separation of variables. We present these equations in the first-order form and study their properties. We prove that the only stationary string configuration that crosses the infinite redshift surface and remains regular there is a principal Killing string. A worldsheet of such a string is generated by a principal null geodesic and a timelike at infinity Killing vector field. We obtain principal Killing string solutions in the Myers-Perry metrics with an arbitrary number of dimensions. It is shown that due to the interaction of a string with a rotating black hole, there is an angular momentum transfer from the black hole to the string. We calculate the rate of this transfer in a space-time with an arbitrary number of dimensions. This effect slows down the rotation of the black hole. We discuss possible final stationary configurations of a rotating black hole interacting with a string
Spinning higher dimensional Einstein-Yang-Mills black holes
International Nuclear Information System (INIS)
Ghosh, Sushant G.; Papnoi, Uma
2014-01-01
We construct a Kerr-Newman-like spacetime starting from higher dimensional (HD) Einstein-Yang-Mills black holes via complex transformations suggested by Newman-Janis. The new metrics are a HD generalization of Kerr-Newman spacetimes which has a geometry that is precisely that of Kerr-Newman in 4D corresponding to a Yang-Mills (YM) gauge charge, but the sign of the charge term gets flipped in the HD spacetimes. It is interesting to note that the gravitational contribution of the YM gauge charge, in HD, is indeed opposite (attractive rather than repulsive) to that of the Maxwell charge. The effect of the YM gauge charge on the structure and location of static limit surface and apparent horizon is discussed. We find that static limit surfaces become less prolate with increase in dimensions and are also sensitive to the YM gauge charge, thereby affecting the shape of the ergosphere. We also analyze some thermodynamical properties of these BHs. (orig.)
Spinning higher dimensional Einstein-Yang-Mills black holes
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Sushant G. [Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India); University of Kwa-Zulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, Private Bag 54001, Durban (South Africa); Papnoi, Uma [Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India)
2014-08-15
We construct a Kerr-Newman-like spacetime starting from higher dimensional (HD) Einstein-Yang-Mills black holes via complex transformations suggested by Newman-Janis. The new metrics are a HD generalization of Kerr-Newman spacetimes which has a geometry that is precisely that of Kerr-Newman in 4D corresponding to a Yang-Mills (YM) gauge charge, but the sign of the charge term gets flipped in the HD spacetimes. It is interesting to note that the gravitational contribution of the YM gauge charge, in HD, is indeed opposite (attractive rather than repulsive) to that of the Maxwell charge. The effect of the YM gauge charge on the structure and location of static limit surface and apparent horizon is discussed. We find that static limit surfaces become less prolate with increase in dimensions and are also sensitive to the YM gauge charge, thereby affecting the shape of the ergosphere. We also analyze some thermodynamical properties of these BHs. (orig.)
International Nuclear Information System (INIS)
Gorthi, Sai Siva; Rastogi, Pramod
2009-01-01
A noisy wrapped phase map is the end-output of commonly employed phase estimation methods in digital holographic interferometry. Hence filtering and unwrapping are necessary to obtain continuous phase distributions. This paper introduces a new approach for phase estimation in digital holographic interferometry using the polynomial phase transform. The proposed approach directly provides an accurate estimation of the unwrapped phase distribution from a noisy reconstructed interference field, thereby bypassing cumbersome and error-prone filtering and 2D phase unwrapping procedures
Higher dimensional quantum Hall effect as A-class topological insulator
Energy Technology Data Exchange (ETDEWEB)
Hasebe, Kazuki, E-mail: khasebe@stanford.edu
2014-09-15
We perform a detail study of higher dimensional quantum Hall effects and A-class topological insulators with emphasis on their relations to non-commutative geometry. There are two different formulations of non-commutative geometry for higher dimensional fuzzy spheres: the ordinary commutator formulation and quantum Nambu bracket formulation. Corresponding to these formulations, we introduce two kinds of monopole gauge fields: non-abelian gauge field and antisymmetric tensor gauge field, which respectively realize the non-commutative geometry of fuzzy sphere in the lowest Landau level. We establish connection between the two types of monopole gauge fields through Chern–Simons term, and derive explicit form of tensor monopole gauge fields with higher string-like singularity. The connection between two types of monopole is applied to generalize the concept of flux attachment in quantum Hall effect to A-class topological insulator. We propose tensor type Chern–Simons theory as the effective field theory for membranes in A-class topological insulators. Membranes turn out to be fractionally charged objects and the phase entanglement mediated by tensor gauge field transforms the membrane statistics to be anyonic. The index theorem supports the dimensional hierarchy of A-class topological insulator. Analogies to D-brane physics of string theory are discussed too.
International Nuclear Information System (INIS)
Naumis, Gerardo G.; Bazan, A.; Torres, M.; Aragon, J.L.; Quintero-Torres, R.
2008-01-01
One of the few examples in which the physical properties of an incommensurable system reflect an underlying higher dimensionality is presented. Specifically, we show that the reflectivity distribution of an incommensurable one-dimensional cavity is given by the density of states of a tight-binding Hamiltonian in a two-dimensional triangular lattice. Such effect is due to an independent phase decoupling of the scattered waves, produced by the incommensurable nature of the system, which mimics a random noise generator. This principle can be applied to design a cavity that avoids resonant reflections for almost any incident wave. An optical analogy, by using three mirrors with incommensurable distances between them, is also presented. Such array produces a countable infinite fractal set of reflections, a phenomena which is opposite to the effect of optical invisibility
Quality-guided orientation unwrapping for fringe direction estimation.
Wang, Haixia; Kemao, Qian
2012-02-01
Fringe patterns produced by various optical interferometric techniques encode information such as shape, deformation, and refractive index. Denoising and demodulation are two important procedures to retrieve information from a single closed fringe pattern. Various existing denoising and demodulation techniques require fringe direction/orientation during the processing. Fringe orientation is often easier to obtain but fringe direction is needed in some demodulation techniques. A quality-guided orientation unwrapping scheme is proposed to estimate direction from orientation. Two techniques, one based on windowed Fourier ridges and the other based on fringe gradient, are proposed for the quality-guided orientation unwrapping scheme. The direction qualities are compared for both simulated and experimental fringe patterns. Their application to demodulation technique is also given.
Unwrapping an Ancient Egyptian Mummy Using X-Rays
Hughes, Stephen W.
2010-01-01
This article describes a project of unwrapping an ancient Egyptian mummy using x-ray computed tomography (CT). About 600 x-ray CT images were obtained through the mummified body of a female named Tjetmutjengebtiu (or Jeni for short), who was a singer in the great temple of Karnak in Egypt during the 22nd dynasty (c 945-715 BC). The x-ray CT images…
CSIR Research Space (South Africa)
Mafu, M
2013-09-01
Full Text Available We present an experimental study of higher-dimensional quantum key distribution protocols based on mutually unbiased bases, implemented by means of photons carrying orbital angular momentum. We perform (d + 1) mutually unbiased measurements in a...
Linear waves on higher dimensional Schwarzschild black holes and Schwarzschild de Sitter spacetimes
Schlue, Volker
2012-01-01
I study linear waves on higher dimensional Schwarzschild black holes and Schwarzschild de Sitter spacetimes. In the first part of this thesis two decay results are proven for general finite energy solutions to the linear wave equation on higher dimensional Schwarzschild black holes. I establish uniform energy decay and improved interior first order energy decay in all dimensions with rates in accordance with the 3 + 1-dimensional case. The method of proof departs from earlier work on th...
Unlabored system motion by specially conditioned electromagnetic fields in higher dimensional realms
David Froning, H.; Meholic, Gregory V.
2010-01-01
This third of three papers explores the possibility of swift, stress-less system transitions between slower-than-light and faster-than-light speeds with negligible net expenditure of system energetics. The previous papers derived a realm of higher dimensionality than 4-D spacetime that enabled such unlabored motion; and showed that fields that could propel and guide systems on unlabored paths in the higher dimensional realm must be fields that have been conditioned to SU(2) (or higher) Lie group symmetry. This paper shows that the system's surrounding vacuum dielectric ɛμ, within the higher dimensional realm's is a vector (not scalar) quantity with fixed magnitude ɛ0μ0 and changing direction within the realm with changing system speed. Thus, ɛμ generated by the system's EM field must remain tuned to vacuum ɛ0μ0 in both magnitude and direction during swift, unlabored system transitions between slower and faster than light speeds. As a result, the system's changing path and speed is such that the magnitude of the higher dimensional realm's ɛ0μ0 is not disturbed. And it is shown that a system's flight trajectories associated with its swift, unlabored transitions between zero and infinite speed can be represented by curved paths traced-out within the higher dimensional realm.
Magnetized black holes and black rings in the higher dimensional dilaton gravity
International Nuclear Information System (INIS)
Yazadjiev, Stoytcho S.
2006-01-01
In this paper we consider magnetized black holes and black rings in the higher dimensional dilaton gravity. Our study is based on exact solutions generated by applying a Harrison transformation to known asymptotically flat black hole and black ring solutions in higher dimensional spacetimes. The explicit solutions include the magnetized version of the higher dimensional Schwarzschild-Tangherlini black holes, Myers-Perry black holes, and five-dimensional (dipole) black rings. The basic physical quantities of the magnetized objects are calculated. We also discuss some properties of the solutions and their thermodynamics. The ultrarelativistic limits of the magnetized solutions are briefly discussed and an explicit example is given for the D-dimensional magnetized Schwarzschild-Tangherlini black holes
Charged particle in higher dimensional weakly charged rotating black hole spacetime
International Nuclear Information System (INIS)
Frolov, Valeri P.; Krtous, Pavel
2011-01-01
We study charged particle motion in weakly charged higher dimensional black holes. To describe the electromagnetic field we use a test field approximation and the higher dimensional Kerr-NUT-(A)dS metric as a background geometry. It is shown that for a special configuration of the electromagnetic field, the equations of motion of charged particles are completely integrable. The vector potential of such a field is proportional to one of the Killing vectors (called a primary Killing vector) from the 'Killing tower' of symmetry generating objects which exists in the background geometry. A free constant in the definition of the adopted electromagnetic potential is proportional to the electric charge of the higher dimensional black hole. The full set of independent conserved quantities in involution is found. We demonstrate that Hamilton-Jacobi equations are separable, as is the corresponding Klein-Gordon equation and its symmetry operators.
Pair creation of higher dimensional black holes on a de Sitter background
International Nuclear Information System (INIS)
Dias, Oscar J.C.; Lemos, Jose P.S.
2004-01-01
We study in detail the quantum process in which a pair of black holes is created in a higher D-dimensional de Sitter (dS) background. The energy to materialize and accelerate the pair comes from the positive cosmological constant. The instantons that describe the process are obtained from the Tangherlini black hole solutions. Our pair creation rates reduce to the pair creation rate for Reissner-Nordstroem-dS solutions when D=4. Pair creation of black holes in the dS background becomes less suppressed when the dimension of the spacetime increases. The dS space is the only background in which we can discuss analytically the pair creation process of higher dimensional black holes, since the C-metric and the Ernst solutions, which describe, respectively, a pair accelerated by a string and by an electromagnetic field, are not known yet in a higher dimensional spacetime
The applications of a higher-dimensional Lie algebra and its decomposed subalgebras
Yu, Zhang; Zhang, Yufeng
2009-01-01
With the help of invertible linear transformations and the known Lie algebras, a higher-dimensional 6 × 6 matrix Lie algebra sμ(6) is constructed. It follows a type of new loop algebra is presented. By using a (2 + 1)-dimensional partial-differential equation hierarchy we obtain the integrable coupling of the (2 + 1)-dimensional KN integrable hierarchy, then its corresponding Hamiltonian structure is worked out by employing the quadratic-form identity. Furthermore, a higher-dimensional Lie algebra denoted by E, is given by decomposing the Lie algebra sμ(6), then a discrete lattice integrable coupling system is produced. A remarkable feature of the Lie algebras sμ(6) and E is used to directly construct integrable couplings. PMID:20084092
World-volume effective theory for higher-dimensional black holes.
Emparan, Roberto; Harmark, Troels; Niarchos, Vasilis; Obers, Niels A
2009-05-15
We argue that the main feature behind novel properties of higher-dimensional black holes, compared to four-dimensional ones, is that their horizons can have two characteristic lengths of very different size. We develop a long-distance world-volume effective theory that captures the black hole dynamics at scales much larger than the short scale. In this limit the black hole is regarded as a blackfold: a black brane (possibly boosted locally) whose world volume spans a curved submanifold of the spacetime. This approach reveals black objects with novel horizon geometries and topologies more complex than the black ring, but more generally it provides a new organizing framework for the dynamics of higher-dimensional black holes.
The applications of a higher-dimensional Lie algebra and its decomposed subalgebras
International Nuclear Information System (INIS)
Yu Zhang; Zhang Yufeng
2009-01-01
With the help of invertible linear transformations and the known Lie algebras, a higher-dimensional 6 x 6 matrix Lie algebra sμ(6) is constructed. It follows a type of new loop algebra is presented. By using a (2 + 1)-dimensional partial-differential equation hierarchy we obtain the integrable coupling of the (2 + 1)-dimensional KN integrable hierarchy, then its corresponding Hamiltonian structure is worked out by employing the quadratic-form identity. Furthermore, a higher-dimensional Lie algebra denoted by E, is given by decomposing the Lie algebra sμ(6), then a discrete lattice integrable coupling system is produced. A remarkable feature of the Lie algebras sμ(6) and E is used to directly construct integrable couplings
The applications of a higher-dimensional Lie algebra and its decomposed subalgebras.
Yu, Zhang; Zhang, Yufeng
2009-01-15
With the help of invertible linear transformations and the known Lie algebras, a higher-dimensional 6 x 6 matrix Lie algebra smu(6) is constructed. It follows a type of new loop algebra is presented. By using a (2 + 1)-dimensional partial-differential equation hierarchy we obtain the integrable coupling of the (2 + 1)-dimensional KN integrable hierarchy, then its corresponding Hamiltonian structure is worked out by employing the quadratic-form identity. Furthermore, a higher-dimensional Lie algebra denoted by E, is given by decomposing the Lie algebra smu(6), then a discrete lattice integrable coupling system is produced. A remarkable feature of the Lie algebras smu(6) and E is used to directly construct integrable couplings.
Using Harry Potter to Bridge Higher Dimensionality in Mathematics and High-interest Literature
Boerman-Cornell, William; Klanderman, David; Schut, Alexa
2017-01-01
The Harry Potter series is a favorite for out-of-school reading and has been used in school, largely as an object of study in language arts. Using a content analysis to highlight the ways in which J.K. Rowling's work could be used to teach higher dimensionality in math, the authors argues that the content is sufficient in such books to engage the…
Existence of local degrees of freedom for higher dimensional pure Chern-Simons theories
International Nuclear Information System (INIS)
Banados, M.; Garay, L.J.; Henneaux, M.
1996-01-01
The canonical structure of higher dimensional pure Chern-Simons theories is analyzed. It is shown that these theories have generically a nonvanishing number of local degrees of freedom, even though they are obtained by means of a topological construction. This number of local degrees of freedom is computed as a function of the spacetime dimension and the dimension of the gauge group. copyright 1996 The American Physical Society
On higher dimensional Einstein spacetimes with a non-degenerate double Weyl aligned null direction
Czech Academy of Sciences Publication Activity Database
Ortaggio, Marcello; Pravda, Vojtěch; Pravdová, Alena
Roč. 35, č. 7 ( 2018 ), č. článku 075004. ISSN 0264-9381 R&D Projects: GA ČR GB14-37086G Institutional support: RVO:67985840 Keywords : higher-dimensional gravity * WANDs * Weyl tensor Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 3.119, year: 2016 http://iopscience.iop.org/article/10.1088/1361-6382/aaae25
International Nuclear Information System (INIS)
Pollock, M.D.
1988-01-01
We consider super-exponential inflation in the early universe, for which H 2 /H = q >> 1, with particular reference to the higher-dimensional theory of Shafi and Wetterich, which is discussed in further detail. The Hubble parameter H is given by H 2 ≅ (8π/3m P 2 )V(Φ), where the ''inflation'' field Φ is related to the radius of the internal space, and obeys the equation of motion 3HΦ ≅ -dW/dΦ. The spectrum of density perturbations is given by δρ/ρ = (M/M 0 ) -s , where s -1 ≅ 3(q + 1); and X = (-dV/dΦ)/(dW/dΦ). The parameters q and X are both positive constants, hence the need for two distinct potentials, which can be met in a higher-dimensional theory with higher-derivative terms R 2 = α 1 R 2 + α 2 R AB R AB + α 3 R ABCD R ABCD . Some fine-tuning of the parameters α i and/or of the cosmological constant Λ is always necessary in order to have super-exponential inflation. It is possible to obtain a spectrum of density perturbations with s > or approx. 1/20, which helps to give agreement with observations of the cosmic microwave background radiation at very large scales ∝ 1000 Mpc. When R 2 is proportional to the Euler number density, making the four-dimensional theory free of ghosts, then super-exponential inflation is impossible, but a phase of inflation with H < 0 can still occur. (orig.)
Iris unwrapping using the Bresenham circle algorithm for real-time iris recognition
Carothers, Matthew T.; Ngo, Hau T.; Rakvic, Ryan N.; Broussard, Randy P.
2015-02-01
An efficient parallel architecture design for the iris unwrapping process in a real-time iris recognition system using the Bresenham Circle Algorithm is presented in this paper. Based on the characteristics of the model parameters this algorithm was chosen over the widely used polar conversion technique as the iris unwrapping model. The architecture design is parallelized to increase the throughput of the system and is suitable for processing an inputted image size of 320 × 240 pixels in real-time using Field Programmable Gate Array (FPGA) technology. Quartus software is used to implement, verify, and analyze the design's performance using the VHSIC Hardware Description Language. The system's predicted processing time is faster than the modern iris unwrapping technique used today∗.
Software Method for Computed Tomography Cylinder Data Unwrapping, Re-slicing, and Analysis
Roth, Don J.
2013-01-01
A software method has been developed that is applicable for analyzing cylindrical and partially cylindrical objects inspected using computed tomography (CT). This method involves unwrapping and re-slicing data so that the CT data from the cylindrical object can be viewed as a series of 2D sheets (or flattened onion skins ) in addition to a series of top view slices and 3D volume rendering. The advantages of viewing the data in this fashion are as follows: (1) the use of standard and specialized image processing and analysis methods is facilitated having 2D array data versus a volume rendering; (2) accurate lateral dimensional analysis of flaws is possible in the unwrapped sheets versus volume rendering; (3) flaws in the part jump out at the inspector with the proper contrast expansion settings in the unwrapped sheets; and (4) it is much easier for the inspector to locate flaws in the unwrapped sheets versus top view slices for very thin cylinders. The method is fully automated and requires no input from the user except proper voxel dimension from the CT experiment and wall thickness of the part. The software is available in 32-bit and 64-bit versions, and can be used with binary data (8- and 16-bit) and BMP type CT image sets. The software has memory (RAM) and hard-drive based modes. The advantage of the (64-bit) RAM-based mode is speed (and is very practical for users of 64-bit Windows operating systems and computers having 16 GB or more RAM). The advantage of the hard-drive based analysis is one can work with essentially unlimited-sized data sets. Separate windows are spawned for the unwrapped/re-sliced data view and any image processing interactive capability. Individual unwrapped images and un -wrapped image series can be saved in common image formats. More information is available at http://www.grc.nasa.gov/WWW/OptInstr/ NDE_CT_CylinderUnwrapper.html.
Directory of Open Access Journals (Sweden)
Muhammad Aslam Noor
2008-01-01
Full Text Available We suggest and analyze a technique by combining the variational iteration method and the homotopy perturbation method. This method is called the variational homotopy perturbation method (VHPM. We use this method for solving higher dimensional initial boundary value problems with variable coefficients. The developed algorithm is quite efficient and is practically well suited for use in these problems. The proposed scheme finds the solution without any discritization, transformation, or restrictive assumptions and avoids the round-off errors. Several examples are given to check the reliability and efficiency of the proposed technique.
A Killing tensor for higher dimensional Kerr-AdS black holes with NUT charge
International Nuclear Information System (INIS)
Davis, Paul
2006-01-01
In this paper, we study the recently discovered family of higher dimensional Kerr-AdS black holes with an extra NUT-like parameter. We show that the inverse metric is additively separable after multiplication by a simple function. This allows us to separate the Hamilton-Jacobi equation, showing that geodesic motion is integrable on this background. The separation of the Hamilton-Jacobi equation is intimately linked to the existence of an irreducible Killing tensor, which provides an extra constant of motion. We also demonstrate that the Klein-Gordon equation for this background is separable
A higher dimensional explanation of the excess of Higgs-like events at CERN LEP
Van der Bij, J J
2006-01-01
Searches for the SM Higgs boson by the four LEP experiments have found a 2.3 sigma excess at 98 GeV and a smaller 1.7 sigma at around 115 GeV. We interpret these excesses as evidence for a Higgs boson coupled to a higher dimensional singlet scalar. The fit implies a relatively low dimensional mixing scale mu_{lhd} 100 GeV. The data show a slight preference for a five-dimensional over a six-dimensional field. This Higgs boson cannot be seen at the LHC, but can be studied at the ILC.
International Nuclear Information System (INIS)
Froning, H. David; Meholic, Gregory V.
2010-01-01
This paper briefly explores higher dimensional spacetimes that extend Meholic's visualizable, fluidic views of: subluminal-luminal-superluminal flight; gravity, inertia, light quanta, and electromagnetism from 2-D to 3-D representations. Although 3-D representations have the potential to better model features of Meholic's most fundamental entities (Transluminal Energy Quantum) and of the zero-point quantum vacuum that pervades all space, the more complex 3-D representations loose some of the clarity of Meholic's 2-D representations of subluminal and superlumimal realms. So, much new work would be needed to replace Meholic's 2-D views of reality with 3-D ones.
Higher dimensional operator corrections to the goldstino Goldberger-Treiman vertices
International Nuclear Information System (INIS)
Lee, T.
2000-01-01
The goldstino-matter interactions given by the Goldberger-Treiman relations can receive higher dimensional operator corrections of O(q 2 /M 2 ), where M denotes the mass of the mediators through which SUSY breaking is transmitted. These corrections in the gauge mediated SUSY breaking models arise from loop diagrams, and an explicit calculation of such corrections is presented. It is emphasized that the Goldberger-Treiman vertices are valid only below the mediator scale, and at higher energies goldstinos decouple from the MSSM fields. The implication of this fact for gravitino cosmology in GMSB models is mentioned. (orig.)
Grand unified theory precursors and nontrivial fixed points in higher-dimensional gauge theories
International Nuclear Information System (INIS)
Dienes, Keith R.; Dudas, Emilian; Gherghetta, Tony
2003-01-01
Within the context of traditional logarithmic grand unification at M GUT ≅10 16 GeV, we show that it is nevertheless possible to observe certain GUT states such as X and Y gauge bosons at lower scales, perhaps even in the TeV range. We refer to such states as 'GUT precursors'. These states offer an interesting alternative possibility for new physics at the TeV scale, and could be used to directly probe GUT physics even though the scale of gauge coupling unification remains high. Our results also give rise to a Kaluza-Klein realization of nontrivial fixed points in higher-dimensional gauge theories
Higher-dimensional bulk wormholes and their manifestations in brane worlds
International Nuclear Information System (INIS)
Rodrigo, Enrico
2006-01-01
There is nothing to prevent a higher-dimensional anti-de Sitter bulk spacetime from containing various other branes in addition to hosting our universe, presumed to be a positive-tension 3-brane. In particular, it could contain closed, microscopic branes that form the boundary surfaces of void bubbles and thus violate the null energy condition in the bulk. The possible existence of such micro branes can be investigated by considering the properties of the ground state of a pseudo-Wheeler-DeWitt equation describing brane quantum dynamics in minisuperspace. If they exist, a concentration of these micro branes could act as a fluid of exotic matter able to support macroscopic wormholes connecting otherwise-distant regions of the bulk. Were the brane constituting our universe to expand into a region of the bulk containing such higher-dimensional macroscopic wormholes, they would likely manifest themselves in our brane as wormholes of normal dimensionality, whose spontaneous appearance and general dynamics would seem inexplicably peculiar. This encounter could also result in the formation of baby universes of a particular type
Identifying Talent in Youth Sport: A Novel Methodology Using Higher-Dimensional Analysis
Till, Kevin; Jones, Ben L.; Cobley, Stephen; Morley, David; O'Hara, John; Chapman, Chris; Cooke, Carlton; Beggs, Clive B.
2016-01-01
Prediction of adult performance from early age talent identification in sport remains difficult. Talent identification research has generally been performed using univariate analysis, which ignores multivariate relationships. To address this issue, this study used a novel higher-dimensional model to orthogonalize multivariate anthropometric and fitness data from junior rugby league players, with the aim of differentiating future career attainment. Anthropometric and fitness data from 257 Under-15 rugby league players was collected. Players were grouped retrospectively according to their future career attainment (i.e., amateur, academy, professional). Players were blindly and randomly divided into an exploratory (n = 165) and validation dataset (n = 92). The exploratory dataset was used to develop and optimize a novel higher-dimensional model, which combined singular value decomposition (SVD) with receiver operating characteristic analysis. Once optimized, the model was tested using the validation dataset. SVD analysis revealed 60 m sprint and agility 505 performance were the most influential characteristics in distinguishing future professional players from amateur and academy players. The exploratory dataset model was able to distinguish between future amateur and professional players with a high degree of accuracy (sensitivity = 85.7%, specificity = 71.1%; ptalent identification. PMID:27224653
Identifying Talent in Youth Sport: A Novel Methodology Using Higher-Dimensional Analysis.
Till, Kevin; Jones, Ben L; Cobley, Stephen; Morley, David; O'Hara, John; Chapman, Chris; Cooke, Carlton; Beggs, Clive B
2016-01-01
Prediction of adult performance from early age talent identification in sport remains difficult. Talent identification research has generally been performed using univariate analysis, which ignores multivariate relationships. To address this issue, this study used a novel higher-dimensional model to orthogonalize multivariate anthropometric and fitness data from junior rugby league players, with the aim of differentiating future career attainment. Anthropometric and fitness data from 257 Under-15 rugby league players was collected. Players were grouped retrospectively according to their future career attainment (i.e., amateur, academy, professional). Players were blindly and randomly divided into an exploratory (n = 165) and validation dataset (n = 92). The exploratory dataset was used to develop and optimize a novel higher-dimensional model, which combined singular value decomposition (SVD) with receiver operating characteristic analysis. Once optimized, the model was tested using the validation dataset. SVD analysis revealed 60 m sprint and agility 505 performance were the most influential characteristics in distinguishing future professional players from amateur and academy players. The exploratory dataset model was able to distinguish between future amateur and professional players with a high degree of accuracy (sensitivity = 85.7%, specificity = 71.1%; ptalent identification.
Upper Estimates on the Higher-dimensional Multifractal Spectrum of Local Entropy%局部熵高维重分形谱的上界估计
Institute of Scientific and Technical Information of China (English)
严珍珍; 陈二才
2008-01-01
We discuss the problem of higher-dimensional multifractal spectrum of lo-cal entropy for arbitrary invariant measures. By utilizing characteristics of a dynam-ical system, namely, higher-dimensional entropy capacities and higher-dimensional correlation entropies, we obtain three upper estimates on the higher-dimensional mul-tifractal spectrum of local entropies. We also study the domain of higher-dimensional multifractal spetrum of entropies.
Schure, Mark R; Davis, Joe M
2017-11-10
Orthogonality metrics (OMs) for three and higher dimensional separations are proposed as extensions of previously developed OMs, which were used to evaluate the zone utilization of two-dimensional (2D) separations. These OMs include correlation coefficients, dimensionality, information theory metrics and convex-hull metrics. In a number of these cases, lower dimensional subspace metrics exist and can be readily calculated. The metrics are used to interpret previously generated experimental data. The experimental datasets are derived from Gilar's peptide data, now modified to be three dimensional (3D), and a comprehensive 3D chromatogram from Moore and Jorgenson. The Moore and Jorgenson chromatogram, which has 25 identifiable 3D volume elements or peaks, displayed good orthogonality values over all dimensions. However, OMs based on discretization of the 3D space changed substantially with changes in binning parameters. This example highlights the importance in higher dimensions of having an abundant number of retention times as data points, especially for methods that use discretization. The Gilar data, which in a previous study produced 21 2D datasets by the pairing of 7 one-dimensional separations, was reinterpreted to produce 35 3D datasets. These datasets show a number of interesting properties, one of which is that geometric and harmonic means of lower dimensional subspace (i.e., 2D) OMs correlate well with the higher dimensional (i.e., 3D) OMs. The space utilization of the Gilar 3D datasets was ranked using OMs, with the retention times of the datasets having the largest and smallest OMs presented as graphs. A discussion concerning the orthogonality of higher dimensional techniques is given with emphasis on molecular diversity in chromatographic separations. In the information theory work, an inconsistency is found in previous studies of orthogonality using the 2D metric often identified as %O. A new choice of metric is proposed, extended to higher dimensions
Bulk emission by higher-dimensional black holes: almost perfect blackbody radiation
International Nuclear Information System (INIS)
Hod, Shahar
2011-01-01
We study the Hawking radiation emitted into the bulk by (D + 1)-dimensional Schwarzschild black holes. It is well known that the black-hole spectrum departs from exact blackbody form due to the frequency dependence of the 'greybody' factors. For intermediate values of D (3 ≤ D ∼ > 1, the typical wavelengths in the black-hole spectrum are much shorter than the size of the black hole. In this regime, the greybody factors are well described by the geometric-optics approximation according to which they are almost frequency independent. Following this observation, we argue that for higher-dimensional black holes with D >> 1, the total power emitted into the bulk should be well approximated by the analytical formula for perfect blackbody radiation. We test the validity of this analytical prediction with numerical computations.
The universe as a topological defect in a higher-dimensional Einstein-Yang-Mills theory
International Nuclear Information System (INIS)
Nakamura, A.; Shiraishi, K.
1989-04-01
An interpretation is suggested that a spontaneous compactification of space-time can be regarded as a topological defect in a higher-dimensional Einstein-Yang-Mills (EYM) theory. We start with D-dimensional EYM theory in our present analysis. A compactification leads to a D-2 dimensional effective action of Abelian gauge-Higgs theory. We find a 'vortex' solution in the effective theory. Our universe appears to be confined in a center of a 'vortex', which has D-4 large dimensions. In this paper we show an example with SU (2) symmetry in the original EYM theory, and the resulting solution is found to be equivalent to the 'instanton-induced compactification'. The cosmological implication is also mentioned. (author)
Higher-dimensional black holes: hidden symmetries and separation of variables
International Nuclear Information System (INIS)
Frolov, Valeri P; Kubiznak, David
2008-01-01
In this paper, we discuss hidden symmetries in rotating black hole spacetimes. We start with an extended introduction which mainly summarizes results on hidden symmetries in four dimensions and introduces Killing and Killing-Yano tensors, objects responsible for hidden symmetries. We also demonstrate how starting with a principal CKY tensor (that is a closed non-degenerate conformal Killing-Yano 2-form) in 4D flat spacetime one can 'generate' the 4D Kerr-NUT-(A)dS solution and its hidden symmetries. After this we consider higher-dimensional Kerr-NUT-(A)dS metrics and demonstrate that they possess a principal CKY tensor which allows one to generate the whole tower of Killing-Yano and Killing tensors. These symmetries imply complete integrability of geodesic equations and complete separation of variables for the Hamilton-Jacobi, Klein-Gordon and Dirac equations in the general Kerr-NUT-(A)dS metrics
Principal Killing strings in higher-dimensional Kerr-NUT-(A)dS spacetimes
Boos, Jens; Frolov, Valeri P.
2018-04-01
We construct special solutions of the Nambu-Goto equations for stationary strings in a general Kerr-NUT-(A)dS spacetime in any number of dimensions. This construction is based on the existence of explicit and hidden symmetries generated by the principal tensor which exists for these metrics. The characteristic property of these string configurations, which we call "principal Killing strings," is that they are stretched out from "infinity" to the horizon of the Kerr-NUT-(A)dS black hole and remain regular at the latter. We also demonstrate that principal Killing strings extract angular momentum from higher-dimensional rotating black holes and interpret this as the action of an asymptotic torque.
Euclidean scalar Green function in a higher dimensional global monopole space-time
International Nuclear Information System (INIS)
Bezerra de Mello, E.R.
2002-01-01
We construct the explicit Euclidean scalar Green function associated with a massless field in a higher dimensional global monopole space-time, i.e., a (1+d)-space-time with d≥3 which presents a solid angle deficit. Our result is expressed in terms of an infinite sum of products of Legendre functions with Gegenbauer polynomials. Although this Green function cannot be expressed in a closed form, for the specific case where the solid angle deficit is very small, it is possible to develop the sum and obtain the Green function in a more workable expression. Having this expression it is possible to calculate the vacuum expectation value of some relevant operators. As an application of this formalism, we calculate the renormalized vacuum expectation value of the square of the scalar field, 2 (x)> Ren , and the energy-momentum tensor, μν (x)> Ren , for the global monopole space-time with spatial dimensions d=4 and d=5
Kragh, John F; Aden, James K; Lambert, Connor D; Moore, Virgil K; Dubick, Michael A
The purpose of this study was to gather data about unwrapping a packaged limb tourniquet from its plastic wrapper while wearing different types of gloves. Because already unwrapped tourniquets require no time to unwrap, unwrapping data may provide insights into the issue of having tourniquets unwrapped when stowed in a first aid kit of a Serviceperson at war. In a laboratory setting, 36 tests of nine glove groups were performed in which four people, gloved and ungloved, unwrapped tourniquets. Other tourniquets were environmentally exposed for 3 months. All the users successfully unwrapped each tourniquet. Mean times to unwrap by glove group were not significantly different (p = .0961). When mean values of eight experimental groups were compared with that of one control group (i.e., bare hands), results showed no significant difference (p > .07). Mean time was least for bare hands (12 seconds) and most for cold gloves layered under mittens (22 seconds). Among the 36 pairwise comparisons of difference between glove group means, after adjustment for multiple comparisons, no comparison was noted to be statistically significant (p > .052, all 36 pairs). Glove thickness ranged from 0 mm for bare hands to 2.5 mm for cold gloves layered under mittens. By glove group, the thickness-time association was moderate, as tested by linear regression (R2 = 0.6096). The tourniquets exposed to the environment had evidence of rapid photodegradation due to direct exposure to sunlight. Such exposure also destroyed the wrappers. In a preliminary study, different gloves performed similarly when wearers unwrapped a tourniquet from its wrapper. The tourniquet wrappers gave no visible protection from sunlight, and environmental exposure destroyed the wrappers. 2017.
Identifying Talent in Youth Sport: A Novel Methodology Using Higher-Dimensional Analysis.
Directory of Open Access Journals (Sweden)
Kevin Till
Full Text Available Prediction of adult performance from early age talent identification in sport remains difficult. Talent identification research has generally been performed using univariate analysis, which ignores multivariate relationships. To address this issue, this study used a novel higher-dimensional model to orthogonalize multivariate anthropometric and fitness data from junior rugby league players, with the aim of differentiating future career attainment. Anthropometric and fitness data from 257 Under-15 rugby league players was collected. Players were grouped retrospectively according to their future career attainment (i.e., amateur, academy, professional. Players were blindly and randomly divided into an exploratory (n = 165 and validation dataset (n = 92. The exploratory dataset was used to develop and optimize a novel higher-dimensional model, which combined singular value decomposition (SVD with receiver operating characteristic analysis. Once optimized, the model was tested using the validation dataset. SVD analysis revealed 60 m sprint and agility 505 performance were the most influential characteristics in distinguishing future professional players from amateur and academy players. The exploratory dataset model was able to distinguish between future amateur and professional players with a high degree of accuracy (sensitivity = 85.7%, specificity = 71.1%; p<0.001, although it could not distinguish between future professional and academy players. The validation dataset model was able to distinguish future professionals from the rest with reasonable accuracy (sensitivity = 83.3%, specificity = 63.8%; p = 0.003. Through the use of SVD analysis it was possible to objectively identify criteria to distinguish future career attainment with a sensitivity over 80% using anthropometric and fitness data alone. As such, this suggests that SVD analysis may be a useful analysis tool for research and practice within talent identification.
Fractal zeta functions and fractal drums higher-dimensional theory of complex dimensions
Lapidus, Michel L; Žubrinić, Darko
2017-01-01
This monograph gives a state-of-the-art and accessible treatment of a new general higher-dimensional theory of complex dimensions, valid for arbitrary bounded subsets of Euclidean spaces, as well as for their natural generalization, relative fractal drums. It provides a significant extension of the existing theory of zeta functions for fractal strings to fractal sets and arbitrary bounded sets in Euclidean spaces of any dimension. Two new classes of fractal zeta functions are introduced, namely, the distance and tube zeta functions of bounded sets, and their key properties are investigated. The theory is developed step-by-step at a slow pace, and every step is well motivated by numerous examples, historical remarks and comments, relating the objects under investigation to other concepts. Special emphasis is placed on the study of complex dimensions of bounded sets and their connections with the notions of Minkowski content and Minkowski measurability, as well as on fractal tube formulas. It is shown for the f...
Araneda, Bernardo
2018-04-01
We present weighted covariant derivatives and wave operators for perturbations of certain algebraically special Einstein spacetimes in arbitrary dimensions, under which the Teukolsky and related equations become weighted wave equations. We show that the higher dimensional generalization of the principal null directions are weighted conformal Killing vectors with respect to the modified covariant derivative. We also introduce a modified Laplace–de Rham-like operator acting on tensor-valued differential forms, and show that the wave-like equations are, at the linear level, appropriate projections off shell of this operator acting on the curvature tensor; the projection tensors being made out of weighted conformal Killing–Yano tensors. We give off shell operator identities that map the Einstein and Maxwell equations into weighted scalar equations, and using adjoint operators we construct solutions of the original field equations in a compact form from solutions of the wave-like equations. We study the extreme and zero boost weight cases; extreme boost corresponding to perturbations of Kundt spacetimes (which includes near horizon geometries of extreme black holes), and zero boost to static black holes in arbitrary dimensions. In 4D our results apply to Einstein spacetimes of Petrov type D and make use of weighted Killing spinors.
International Nuclear Information System (INIS)
Rami, El-Nabulsi Ahmad
2009-01-01
Higher dimensional cosmological implications of a decay law for the cosmological constant term are analyzed. Three independent cosmological models are explored mainly: 1) In the first model, the effective cosmological constant was chosen to decay with times like Δ effective = Ca -2 + D(b/a I ) 2 where a I is an arbitrary scale factor characterizing the isotropic epoch which proceeds the graceful exit period. Further, the extra-dimensional scale factor decays classically like b(t) approx. a x (t), x is a real negative number. 2) In the second model, we adopt in addition to Δ effective = Ca -2 + D(b/a I ) 2 the phenomenological law b(t) = a(t)exp( -Qt) as we expect that at the origin of time, there is no distinction between the visible and extra dimensions; Q is a real number. 3) In the third model, we study a Δ - decaying extra-dimensional cosmology with a static traversable wormhole in which the four-dimensional Friedmann-Robertson-Walker spacetime is subject to the conventional perfect fluid while the extra-dimensional part is endowed by an exotic fluid violating strong energy condition and where the cosmological constant in (3+n+1) is assumed to decays like Δ(a) = 3Ca -2 . The three models are discussed and explored in some details where many interesting points are revealed. (author)
Generalized Uncertainty Principle and Black Hole Entropy of Higher-Dimensional de Sitter Spacetime
International Nuclear Information System (INIS)
Zhao Haixia; Hu Shuangqi; Zhao Ren; Li Huaifan
2007-01-01
Recently, there has been much attention devoted to resolving the quantum corrections to the Bekenstein-Hawking black hole entropy. In particular, many researchers have expressed a vested interest in the coefficient of the logarithmic term of the black hole entropy correction term. In this paper, we calculate the correction value of the black hole entropy by utilizing the generalized uncertainty principle and obtain the correction term caused by the generalized uncertainty principle. Because in our calculation we think that the Bekenstein-Hawking area theorem is still valid after considering the generalized uncertainty principle, we derive that the coefficient of the logarithmic term of the black hole entropy correction term is positive. This result is different from the known result at present. Our method is valid not only for four-dimensional spacetimes but also for higher-dimensional spacetimes. In the whole process, the physics idea is clear and calculation is simple. It offers a new way for studying the entropy correction of the complicated spacetime.
Kanti, P.; Pappas, T.
2017-07-01
The absence of a true thermodynamical equilibrium for an observer located in the causal area of a Schwarzschild-de Sitter spacetime has repeatedly raised the question of the correct definition of its temperature. In this work, we consider five different temperatures for a higher-dimensional Schwarzschild-de Sitter black hole: the bare T0, the normalized TBH, and three effective ones given in terms of both the black-hole and cosmological horizon temperatures. We find that these five temperatures exhibit similarities but also significant differences in their behavior as the number of extra dimensions and the value of the cosmological constant are varied. We then investigate their effect on the energy emission spectra of Hawking radiation. We demonstrate that the radiation spectra for the normalized temperature TBH—proposed by Bousso and Hawking over twenty years ago—leads to the dominant emission curve, while the other temperatures either support a significant emission rate only in a specific Λ regime or have their emission rates globally suppressed. Finally, we compute the bulk-over-brane emissivity ratio and show that the use of different temperatures may lead to different conclusions regarding the brane or bulk dominance.
Emission of massive scalar fields by a higher-dimensional rotating black hole
International Nuclear Information System (INIS)
Kanti, P.; Pappas, N.
2010-01-01
We perform a comprehensive study of the emission of massive scalar fields by a higher-dimensional, simply rotating black hole both in the bulk and on the brane. We derive approximate, analytic results as well as exact numerical ones for the absorption probability, and demonstrate that the two sets agree very well in the low and intermediate-energy regime for scalar fields with mass m Φ ≤1 TeV in the bulk and m Φ ≤0.5 TeV on the brane. The numerical values of the absorption probability are then used to derive the Hawking radiation power emission spectra in terms of the number of extra dimensions, angular-momentum of the black hole and mass of the emitted field. We compute the total emissivities in the bulk and on the brane, and demonstrate that, although the brane channel remains the dominant one, the bulk-over-brane energy ratio is considerably increased (up to 34%) when the mass of the emitted field is taken into account.
Spontaneous symmetry breaking and fermion chirality in higher-dimensional gauge theory
International Nuclear Information System (INIS)
Wetterich, C.
1985-01-01
The number of chiral fermions may change in the course of spontaneous symmetry breaking. We discuss solutions of a six-dimensional Einstein-Yang-Mills theory based on SO(12). In the resulting effective four-dimensional theory they can be interpreted as spontaneous breaking of a gauge group SO(10) to H=SU(3)sub(C)xSU(2)sub(L)xU(1)sub(R)xU(1)sub(B-L). For all solutions, the fermions which are chiral with respect to H form standard generations. However, the number of generations for the solutions with broken SO(10) may be different compared to the symmetric solutions. All solutions considered here exhibit a local generation group SU(2)sub(G)xU(1)sub(G). For the solutions with broken SO(10) symmetry, the leptons and quarks within one generation transform differently with respect to SU(2)sub(G)xU(1)sub(G). Spontaneous symmetry breaking also modifies the SO(10) relations among Yukawa couplings. All this has important consequences for possible fermion mass relations obtained from higher-dimensional theories. (orig.)
What we think about the higher dimensional Chern-Simons theories
International Nuclear Information System (INIS)
Fock, V.V.; Nekrasov, N.A.; Rosly, A.A.; Selivanov, K.G.
1992-01-01
This paper reports that one of the most interesting developments in mathematical physics was the investigation of the so-called topological field theories i.e. such theories which do not need a metric on the manifold for their definition a d hence the observable of which are topologically invariant. The Chern-Simons (CS) functionals considered as actions give us examples the theories of such a type. The CS theory on a 3d manifold was firstly considered in the Abelian case by A.S. Schwartz and then after papers of E. Witten there has been an explosive process of publications on this subject. This paper discusses topological invariants of the manifolds (like the Ray-Singer torsion) computed by the quantum field theory methods; conformal blocks of 2d conformal field theories as vectors in the CS theory Hilbert space; correlators of Wilson loop and the invariants of 1d links in 3d manifolds; braid groups; unusual relations between spin and statistics; here we would like to consider the generalization of a part of the outlined ideas to the CS theories on higher dimensional manifolds. Some of our results intersect with
Black holes in higher dimensional gravity theory with corrections quadratic in curvature
International Nuclear Information System (INIS)
Frolov, Valeri P.; Shapiro, Ilya L.
2009-01-01
Static spherically symmetric black holes are discussed in the framework of higher dimensional gravity with quadratic in curvature terms. Such terms naturally arise as a result of quantum corrections induced by quantum fields propagating in the gravitational background. We focus our attention on the correction of the form C 2 =C αβγδ C αβγδ . The Gauss-Bonnet equation in four-dimensional spacetime enables one to reduce this term in the action to the terms quadratic in the Ricci tensor and scalar curvature. As a result the Schwarzschild solution which is Ricci flat will be also a solution of the theory with the Weyl scalar C 2 correction. An important new feature of the spaces with dimension D>4 is that in the presence of the Weyl curvature-squared term a necessary solution differs from the corresponding 'classical' vacuum Tangherlini metric. This difference is related to the presence of secondary or induced hair. We explore how the Tangherlini solution is modified by 'quantum corrections', assuming that the gravitational radius r 0 is much larger than the scale of the quantum corrections. We also demonstrated that finding a general solution beyond the perturbation method can be reduced to solving a single third order ordinary differential equation (master equation).
New developments for determination of uncertainty in phase evaluation
Liu, Sheng
Phase evaluation exists mostly in, but not limited to, interferometric applications that utilize coherent multidimensional signals to modulate the physical quantity of interest into a nonlinear form, represented by repeating the phase modulo of 271 radians. In order to estimate the underlying physical quantity, the wrapped phase has to be unwrapped by an evaluation procedure which is usually called phase unwrapping. The procedure of phase unwrapping will obviously face the challenge of inconsistent phase, which could bring errors in phase evaluation. The main objectives of this research include addressing the problem of inconsistent phase in phase unwrapping and applications in modern optical techniques. In this research, a new phase unwrapping algorithm is developed. The creative idea of doing phase unwrapping between regions has an advantage over conventional pixel-to-pixel unwrapping methods because the unwrapping result is more consistent by using a voting mechanism based on all Zit-discontinuities hints. Furthermore, a systematic sequence of regional unwrapping is constructed in order to achieve a global consistent result. An implementation of the idea is illustrated in dct.il with step-by-step pseudo codes. The performance of the algorithm is demonstrated on real world applications. In order to solve a phase unwrapping problem which is caused by depth discontinuities in 3D shape measurement, a new absolute phase coding strategy is developed. The algorithm presented has two merits: effectively extends the coding range and preserves the measurement sensitivity. The performance of the proposed absolute coding strategy is proved by results of 3D shape measurement for objects with surface discontinuities. As a powerful tool for real world applications a universal software package, Optical Measurement and Evaluation Software (OMES), is designed for the purposes of automatic measurement and quantitative evaluation in 3D shape measurement and laser interferometry
Vacuum polarization and classical self-action near higher-dimensional defects
Energy Technology Data Exchange (ETDEWEB)
Grats, Yuri V.; Spirin, Pavel [Moscow State University, Department of Theoretical Physics, Faculty of Physics, Moscow (Russian Federation)
2017-02-15
We analyze the gravity-induced effects associated with a massless scalar field in a higher-dimensional spacetime being the tensor product of (d - n)-dimensional Minkowski space and n-dimensional spherically/cylindrically symmetric space with a solid/planar angle deficit. These spacetimes are considered as simple models for a multidimensional global monopole (if n ≥ 3) or cosmic string (if n = 2) with (d - n - 1) flat extra dimensions. Thus, we refer to them as conical backgrounds. In terms of the angular-deficit value, we derive the perturbative expression for the scalar Green function, valid for any d ≥ 3 and 2 ≤ n ≤ d - 1, and compute it to the leading order. With the use of this Green function we compute the renormalized vacuum expectation value of the field square left angle φ{sup 2}(x) right angle {sub ren} and the renormalized vacuum averaged of the scalar-field energy-momentum tensor left angle T{sub MN}(x) right angle {sub ren} for arbitrary d and n from the interval mentioned above and arbitrary coupling constant to the curvature ξ. In particular, we revisit the computation of the vacuum polarization effects for a non-minimally coupled massless scalar field in the spacetime of a straight cosmic string. The same Green function enables to consider the old purely classical problem of the gravity-induced self-action of a classical point-like scalar or electric charge, placed at rest at some fixed point of the space under consideration. To deal with divergences, which appear in consideration of the two problems, we apply the dimensional-regularization technique, widely used in quantum field theory. The explicit dependence of the results upon the dimensionalities of both the bulk and conical submanifold is discussed. (orig.)
Lohe, M. A.
2018-06-01
We generalize the Watanabe–Strogatz (WS) transform, which acts on the Kuramoto model in d = 2 dimensions, to a higher-dimensional vector transform which operates on vector oscillator models of synchronization in any dimension , for the case of identical frequency matrices. These models have conserved quantities constructed from the cross ratios of inner products of the vector variables, which are invariant under the vector transform, and have trajectories which lie on the unit sphere S d‑1. Application of the vector transform leads to a partial integration of the equations of motion, leaving independent equations to be solved, for any number of nodes N. We discuss properties of complete synchronization and use the reduced equations to derive a stability condition for completely synchronized trajectories on S d‑1. We further generalize the vector transform to a mapping which acts in and in particular preserves the unit ball , and leaves invariant the cross ratios constructed from inner products of vectors in . This mapping can be used to partially integrate a system of vector oscillators with trajectories in , and for d = 2 leads to an extension of the Kuramoto system to a system of oscillators with time-dependent amplitudes and trajectories in the unit disk. We find an inequivalent generalization of the Möbius map which also preserves but leaves invariant a different set of cross ratios, this time constructed from the vector norms. This leads to a different extension of the Kuramoto model with trajectories in the complex plane that can be partially integrated by means of fractional linear transformations.
Directory of Open Access Journals (Sweden)
ShuZheng Yang
2016-01-01
Full Text Available Based on semiclassical tunneling method, we focus on charged fermions tunneling from higher-dimensional Reissner-Nordström black hole. We first simplify the Dirac equation by semiclassical approximation, and then a semiclassical Hamilton-Jacobi equation is obtained. Using the Hamilton-Jacobi equation, we study the Hawking temperature and fermions tunneling rate at the event horizon of the higher-dimensional Reissner-Nordström black hole space-time. Finally, the correct entropy is calculation by the method beyond semiclassical approximation.
Hong, Sungwoo
Warped higher-dimensional compactifications with "bulk'' standard model, or their AdS/CFT dual as the purely 4D scenario of Higgs compositeness and partial compositeness, offer an elegant approach to resolving the electroweak hierarchy problem as well as the origins of flavor structure. However, low-energy electroweak/flavor/CP constraints and the absence of non-standard physics at LHC Run 1 suggest that a "little hierarchy problem'' remains, and that the new physics underlying naturalness may lie out of LHC reach. Assuming this to be the case, we show that there is a simple and natural extension of the minimal warped model in the Randall-Sundrum framework, in which matter, gauge and gravitational fields propagate modestly different degrees into the IR of the warped dimension, resulting in rich and striking consequences for the LHC (and beyond). The LHC-accessible part of the new physics is AdS/CFT dual to the mechanism of "vectorlike confinement'', with TeV-scale Kaluza-Klein excitations of the gauge and gravitational fields dual to spin-0,1,2 composites. Unlike the minimal warped model, these low-lying excitations have predominantly flavor-blind and flavor/CP-safe interactions with the standard model. In addition, the usual leading decay modes of the lightest KK gauge bosons into top and Higgs bosons are suppressed. This effect permits erstwhile subdominant channels to become significant. These include flavor-universal decays to all pairs of SM fermions, and a novel channel--decay to a radion and a SM gauge boson, followed by radion decay to a pair of SM gauge bosons. We present a detailed phenomenological study of the latter cascade decay processes. Remarkably, this scenario also predicts small deviations from flavor-blindness originating from virtual effects of Higgs/top compositeness at O(10) TeV, with subdominant resonance decays into a pair of Higgs/top-rich final states, giving the LHC an early "preview'' of the nature of the resolution of the hierarchy
Zhang, Zhenhai; Li, Kejie; Wu, Xiaobing; Zhang, Shujiang
2008-03-01
The unwrapped and correcting algorithm based on Coordinate Rotation Digital Computer (CORDIC) and bilinear interpolation algorithm was presented in this paper, with the purpose of processing dynamic panoramic annular image. An original annular panoramic image captured by panoramic annular lens (PAL) can be unwrapped and corrected to conventional rectangular image without distortion, which is much more coincident with people's vision. The algorithm for panoramic image processing is modeled by VHDL and implemented in FPGA. The experimental results show that the proposed panoramic image algorithm for unwrapped and distortion correction has the lower computation complexity and the architecture for dynamic panoramic image processing has lower hardware cost and power consumption. And the proposed algorithm is valid.
Directory of Open Access Journals (Sweden)
Hasibun Naher
2012-01-01
Full Text Available We construct new analytical solutions of the (3+1-dimensional modified KdV-Zakharov-Kuznetsev equation by the Exp-function method. Plentiful exact traveling wave solutions with arbitrary parameters are effectively obtained by the method. The obtained results show that the Exp-function method is effective and straightforward mathematical tool for searching analytical solutions with arbitrary parameters of higher-dimensional nonlinear partial differential equation.
Testud, Frederik; Gallichan, Daniel; Layton, Kelvin J; Barmet, Christoph; Welz, Anna M; Dewdney, Andrew; Cocosco, Chris A; Pruessmann, Klaas P; Hennig, Jürgen; Zaitsev, Maxim
2015-03-01
PatLoc (Parallel Imaging Technique using Localized Gradients) accelerates imaging and introduces a resolution variation across the field-of-view. Higher-dimensional encoding employs more spatial encoding magnetic fields (SEMs) than the corresponding image dimensionality requires, e.g. by applying two quadratic and two linear spatial encoding magnetic fields to reconstruct a 2D image. Images acquired with higher-dimensional single-shot trajectories can exhibit strong artifacts and geometric distortions. In this work, the source of these artifacts is analyzed and a reliable correction strategy is derived. A dynamic field camera was built for encoding field calibration. Concomitant fields of linear and nonlinear spatial encoding magnetic fields were analyzed. A combined basis consisting of spherical harmonics and concomitant terms was proposed and used for encoding field calibration and image reconstruction. A good agreement between the analytical solution for the concomitant fields and the magnetic field simulations of the custom-built PatLoc SEM coil was observed. Substantial image quality improvements were obtained using a dynamic field camera for encoding field calibration combined with the proposed combined basis. The importance of trajectory calibration for single-shot higher-dimensional encoding is demonstrated using the combined basis including spherical harmonics and concomitant terms, which treats the concomitant fields as an integral part of the encoding. © 2014 Wiley Periodicals, Inc.
Pappas, T.; Kanti, P.; Pappas, N.
2016-01-01
In this work, we study the propagation of scalar fields in the gravitational background of a higher-dimensional Schwarzschild-de-Sitter black hole as well as on the projected-on-the-brane 4-dimensional background. The scalar fields have also a non-minimal coupling to the corresponding, bulk or brane, scalar curvature. We perform a comprehensive study by deriving exact numerical results for the greybody factors, and study their profile in terms of particle and spacetime properties. We then pro...
Pappas, T.; Kanti, P.; Pappas, N.
2016-07-01
In this work, we study the propagation of scalar fields in the gravitational background of a higher-dimensional Schwarzschild-de Sitter black hole as well as on the projected-on-the-brane four-dimensional background. The scalar fields have also a nonminimal coupling to the corresponding, bulk or brane, scalar curvature. We perform a comprehensive study by deriving exact numerical results for the greybody factors, and study their profile in terms of particle and spacetime properties. We then proceed to derive the Hawking radiation spectra for a higher-dimensional Schwarzschild-de Sitter black hole, and we study both bulk and brane channels. We demonstrate that the nonminimal field coupling, which creates an effective mass term for the fields, suppresses the energy emission rates while the cosmological constant assumes a dual role. By computing the relative energy rates and the total emissivity ratio for bulk and brane emission, we demonstrate that the combined effect of a large number of extra dimensions and value of the field coupling gives to the bulk channel the clear domination in the bulk-brane energy balance.
Research Note: Full-waveform inversion of the unwrapped phase of a model
Alkhalifah, Tariq Ali
2013-01-01
, convergence to a solution becomes difficult. As a result, we tend to invert for refracted events and damp reflections in data. Reflection induced non-linearity stems from cycle skipping between the imprint of the true model in observed data and the predicted
Wave equation tomography using the unwrapped phase - Analysis of the traveltime sensitivity kernels
Djebbi, Ramzi; Alkhalifah, Tariq Ali
2013-01-01
equation tomography (WET) tries to improve on traveltime tomography, by better adhering to the requirements of our finite-frequency data. However, conventional (WET), based on the crosscorelaion lag, yields the popular hallow banana sensitivity kernel
International Nuclear Information System (INIS)
Anderson, Gregory W.; Blazek, Tomas
2005-01-01
E 6 is an attractive group for unification model building. However, the complexity of a rank 6 group makes it nontrivial to write down the structure of higher dimensional operators in an E 6 theory in terms of the states labeled by quantum numbers of the standard model gauge group. In this paper, we show the results of our computation of the Clebsch-Gordan coefficients for the products of the 27 with irreducible representations of higher dimensionality: 78, 351, 351 ' , 351, and 351 ' . Application of these results to E 6 model building involving higher dimensional operators is straightforward
Energy Technology Data Exchange (ETDEWEB)
Lin Kai, E-mail: lk314159@126.co [Institute of Theoretical Physics, China West Normal University, NanChong, SiChuan 637002 (China); Yang Shuzheng, E-mail: szyangcwnu@126.co [Institute of Theoretical Physics, China West Normal University, NanChong, SiChuan 637002 (China)
2009-10-12
Applying the method beyond semiclassical approximation, fermion tunneling from higher-dimensional anti-de Sitter Schwarzschild black hole is researched. In our work, the 'tortoise' coordinate transformation is introduced to simplify Dirac equation, so that the equation proves that only the (r-t) sector is important to our research. Because we only need to study the (r-t) sector, the Dirac equation is decomposed into several pairs of equations spontaneously, and we then prove the components of wave functions are proportional to each other in every pair of equations. Therefore, the suitable action forms of the wave functions are obtained, and finally the correctional Hawking temperature and entropy can be determined via the method beyond semiclassical approximation.
International Nuclear Information System (INIS)
Abbagari, Souleymanou; Bouetou, Thomas B.; Kofane, Timoleon C.
2013-01-01
The prolongation structure methodologies of Wahlquist—Estabrook [H.D. Wahlquist and F.B. Estabrook, J. Math. Phys. 16 (1975) 1] for nonlinear differential equations are applied to a more general set of coupled integrable dispersionless system. Based on the obtained prolongation structure, a Lie-Algebra valued connection of a closed ideal of exterior differential forms related to the above system is constructed. A Lie-Algebra representation of some hidden structural symmetries of the previous system, its Bäcklund transformation using the Riccati form of the linear eigenvalue problem and their general corresponding Lax-representation are derived. In the wake of the previous results, we extend the above prolongation scheme to higher-dimensional systems from which a new (2 + 1)-dimensional coupled integrable dispersionless system is unveiled along with its inverse scattering formulation, which applications are straightforward in nonlinear optics where additional propagating dimension deserves some attention. (general)
International Nuclear Information System (INIS)
Kuetche, Victor Kamgang; Bouetou, Thomas Bouetou; Kofane, Timoleon Crepin
2010-12-01
We investigate the singularity structure analysis of the higher-dimensional time-gated Manakov system referring to the (2+1)-dimensional coupled nonlinear Schroedinger (CNLS) equations, and we show that these equations are Painleve-integrable. By means of the Weiss et al.'s methodology, we show the arbitrariness of the expansion coefficients and the consistency of the truncation corresponding to a special Baecklund transformation (BT) of these CNLS equations. In the wake of such transformation, following the Hirota's formalism, we derive a one-soliton solution. Besides, by using the Zakharov-Shabat (ZS) scheme which provides a general Lax-representation of an evolution system, we show that the (2+1)-dimensional CNLS system under interests is completely integrable. Furthermore, using the arbitrariness of the above coefficients, we unearth and investigate a typical spectrum of periodic coherent structures while depicting elastic interactions amongst such patterns. (author)
Humidification of unwrapped chilled meat on retail display using an ultrasonic fogging system.
Brown, Tim; Corry, Janet E L; Evans, Judith A
2007-12-01
The effects of an ultrasonic humidification system on unwrapped meat in a chilled retail display cabinet were assessed. Humidification raised the relative humidity of the cabinet air from a mean of 76.7% to just below saturation at 98.8%. This reduced the mean evaporative weight loss from whole samples of meat after 14h from 1.68% to 0.62% of their initial weight. The rate of deterioration in the appearance of the meat due to dehydration was reduced to the extent that while the unhumidified trial was terminated after 14h because all samples were judged to be unacceptable, the humidified trial was continued for 24h without any major changes in appearance. Levels of presumptive pseudomonas bacteria were relatively high in water samples taken from the humidification system and defrost water during the humidified trial, but Legionella spp. were not isolated. Significant increases in the numbers of bacteria on the meat during either trial were only found in one case, that of humidified minced beef. However, some of the samples had high counts even before display, and this may have masked any effect due to humidification. Differences in levels of air-borne contamination were small and inconsistent. Air temperatures were raised by humidification by between 1 and 2°C and this was reflected in similarly raised product temperatures. Temperatures of air leaving the evaporator indicated that this was due to icing of the evaporator in the periods leading up to defrosts.
Institute of Scientific and Technical Information of China (English)
XU Dian-Yan
2003-01-01
The free energy and entropy of Reissner-Nordstrom black holes in higher-dimensional space-time are calculated by the quantum statistic method with a brick wall model. The space-time of the black holes is divided into three regions: region 1, (r > r0); region 2, (r0 > r > n); and region 3, (T-J > r > 0), where r0 is the radius of the outer event horizon, and r, is the radius of the inner event horizon. Detailed calculation shows that the entropy contributed by region 2 is zero, the entropy contributed by region 1 is positive and proportional to the outer event horizon area, the entropy contributed by region 3 is negative and proportional to the inner event horizon area. The total entropy contributed by all the three regions is positive and proportional to the area difference between the outer and inner event horizons. As rt approaches r0 in the nearly extreme case, the total quantum statistical entropy approaches zero.
Energy Technology Data Exchange (ETDEWEB)
Furuuchi, Kazuyuki [Manipal Centre for Natural Sciences, Manipal University,Manipal, Karnataka 576104 (India); Koyama, Yoji [National Center for Theoretical Sciences, National Tsing-Hua University,Hsinchu 30013, Taiwan R.O.C. (China)
2016-06-21
We continue our investigation of large field inflation models obtained from higher-dimensional gauge theories, initiated in our previous study http://dx.doi.org/10.1088/1475-7516/2015/02/031. We focus on Dante’s Inferno model which was the most preferred model in our previous analysis. We point out the relevance of the IR obstruction to UV completion, which constrains the form of the potential of the massive vector field, under the current observational upper bound on the tensor to scalar ratio. We also show that in simple examples of the potential arising from DBI action of a D5-brane and that of an NS5-brane that the inflation takes place in the field range which is within the convergence radius of the Taylor expansion. This is in contrast to the well known examples of axion monodromy inflation where inflaton takes place outside the convergence radius of the Taylor expansion. This difference arises from the very essence of Dante’s Inferno model that the effective inflaton potential is stretched in the inflaton field direction compared with the potential for the original field.
International Nuclear Information System (INIS)
Furuuchi, Kazuyuki; Koyama, Yoji
2016-01-01
We continue our investigation of large field inflation models obtained from higher-dimensional gauge theories, initiated in our previous study http://dx.doi.org/10.1088/1475-7516/2015/02/031. We focus on Dante’s Inferno model which was the most preferred model in our previous analysis. We point out the relevance of the IR obstruction to UV completion, which constrains the form of the potential of the massive vector field, under the current observational upper bound on the tensor to scalar ratio. We also show that in simple examples of the potential arising from DBI action of a D5-brane and that of an NS5-brane that the inflation takes place in the field range which is within the convergence radius of the Taylor expansion. This is in contrast to the well known examples of axion monodromy inflation where inflaton takes place outside the convergence radius of the Taylor expansion. This difference arises from the very essence of Dante’s Inferno model that the effective inflaton potential is stretched in the inflaton field direction compared with the potential for the original field.
Phase estimation for global defocus correction in optical coherence tomography
DEFF Research Database (Denmark)
Jensen, Mikkel; Israelsen, Niels Møller; Podoleanu, Adrian
2017-01-01
In this work we investigate three techniques for estimation of the non-linear phase present due to defocus in opticalcoherence tomography, and apply them with the angular spectrum method. The techniques are: Least squarestting the of unwrapped phase of the angular spectrum, iterative optimization......, and sub-aperture correlations. The estimated phase of a single en-face image is used to extrapolate the non-linear phase at all depths, whichin the end can be used to correct the entire 3-D tomogram, and any other tomogram from the same system.......In this work we investigate three techniques for estimation of the non-linear phase present due to defocus in opticalcoherence tomography, and apply them with the angular spectrum method. The techniques are: Least squarestting the of unwrapped phase of the angular spectrum, iterative optimization...
Robust water fat separated dual-echo MRI by phase-sensitive reconstruction.
Romu, Thobias; Dahlström, Nils; Leinhard, Olof Dahlqvist; Borga, Magnus
2017-09-01
The purpose of this work was to develop and evaluate a robust water-fat separation method for T1-weighted symmetric two-point Dixon data. A method for water-fat separation by phase unwrapping of the opposite-phase images by phase-sensitive reconstruction (PSR) is introduced. PSR consists of three steps; (1), identification of clusters of tissue voxels; (2), unwrapping of the phase in each cluster by solving Poisson's equation; and (3), finding the correct sign of each unwrapped opposite-phase cluster, so that the water-fat images are assigned the correct identities. Robustness was evaluated by counting the number of water-fat swap artifacts in a total of 733 image volumes. The method was also compared to commercial software. In the water-fat separated image volumes, the PSR method failed to unwrap the phase of one cluster and misclassified 10. One swap was observed in areas affected by motion and was constricted to the affected area. Twenty swaps were observed surrounding susceptibility artifacts, none of which spread outside the artifact affected regions. The PSR method had fewer swaps when compared to commercial software. The PSR method can robustly produce water-fat separated whole-body images based on symmetric two-echo spoiled gradient echo images, under both ideal conditions and in the presence of common artifacts. Magn Reson Med 78:1208-1216, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.
International Nuclear Information System (INIS)
Akarsu, Özgür; Dereli, Tekin
2013-01-01
We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales
Akarsu, Özgür; Dereli, Tekin
2013-02-01
We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales.
Hanke, Jan-Philipp; Freimuth, Frank; Blügel, Stefan; Mokrousov, Yuriy
2018-04-01
We present an advanced first-principles formalism to evaluate the Dzyaloshinskii-Moriya interaction (DMI) in its modern theory as well as Berry curvatures in complex spaces based on a higher-dimensional Wannier interpolation. Our method is applied to the Co-based trilayer systems IrδPt1-δ/Co/Pt and AuγPt1-γ/Co/Pt, where we gain insights into the correlations between the electronic structure and the DMI, and we uncover prominent sign changes of the chiral interaction with the overlayer composition. Beyond the discussed phenomena, the scope of applications of our Wannier-based scheme is particularly broad as it is ideally suited to study efficiently the Hamiltonian evolution under the slow variation of very general parameters.
Directory of Open Access Journals (Sweden)
Farhad A. Namin
2016-08-01
Full Text Available A rigorous method for obtaining the diffraction patterns of quasicrystals is presented. Diffraction patterns are an essential analytical tool in the study of quasicrystals, since they can be used to determine their photonic resonances. Previous methods for approximating the diffraction patterns of quasicrystals have relied on evaluating the Fourier transform of finite-sized super-lattices. Our approach, on the other hand, is exact in the sense that it is based on a technique that embeds quasicrystals into higher dimensional periodic hyper-lattices, thereby completely capturing the properties of the infinite structure. The periodicity of the unit cell in the higher dimensional space can be exploited to obtain the Fourier series expansion in closed-form of the corresponding atomic surfaces. The utility of the method is demonstrated by applying it to one-dimensional Fibonacci and two-dimensional Penrose quasicrystals. The results are verified by comparing them to those obtained by using the conventional super-lattice method. It is shown that the conventional super-cell approach can lead to inaccurate results due to the continuous nature of the Fourier transform, since quasicrystals have a discrete spectrum, whereas the approach introduced in this paper generates discrete Fourier harmonics. Furthermore, the conventional approach requires very large super-cells and high-resolution sampling of the reciprocal space in order to produce accurate results leading to a very large computational burden, whereas the proposed method generates accurate results with a relatively small number of terms. Finally, we propose how this approach can be generalized from the vertex model, which assumes identical particles at all vertices, to a more realistic case where the quasicrystal is composed of different atoms.
Zhu, Haitao; Nie, Binbin; Liu, Hua; Guo, Hua; Demachi, Kazuyuki; Sekino, Masaki; Shan, Baoci
2016-05-01
Phase map cross-correlation detection and quantification may produce highlighted signal at superparamagnetic iron oxide nanoparticles, and distinguish them from other hypointensities. The method may quantify susceptibility change by performing least squares analysis between a theoretically generated magnetic field template and an experimentally scanned phase image. Because characteristic phase recognition requires the removal of phase wrap and phase background, additional steps of phase unwrapping and filtering may increase the chance of computing error and enlarge the inconsistence among algorithms. To solve problem, phase gradient cross-correlation and quantification method is developed by recognizing characteristic phase gradient pattern instead of phase image because phase gradient operation inherently includes unwrapping and filtering functions. However, few studies have mentioned the detectable limit of currently used phase gradient calculation algorithms. The limit may lead to an underestimation of large magnetic susceptibility change caused by high-concentrated iron accumulation. In this study, mathematical derivation points out the value of maximum detectable phase gradient calculated by differential chain algorithm in both spatial and Fourier domain. To break through the limit, a modified quantification method is proposed by using unwrapped forward differentiation for phase gradient generation. The method enlarges the detectable range of phase gradient measurement and avoids the underestimation of magnetic susceptibility. Simulation and phantom experiments were used to quantitatively compare different methods. In vivo application performs MRI scanning on nude mice implanted by iron-labeled human cancer cells. Results validate the limit of detectable phase gradient and the consequent susceptibility underestimation. Results also demonstrate the advantage of unwrapped forward differentiation compared with differential chain algorithms for susceptibility
Ding, Yi; Peng, Kai; Yu, Miao; Lu, Lei; Zhao, Kun
2017-08-01
The performance of the two selected spatial frequency phase unwrapping methods is limited by a phase error bound beyond which errors will occur in the fringe order leading to a significant error in the recovered absolute phase map. In this paper, we propose a method to detect and correct the wrong fringe orders. Two constraints are introduced during the fringe order determination of two selected spatial frequency phase unwrapping methods. A strategy to detect and correct the wrong fringe orders is also described. Compared with the existing methods, we do not need to estimate the threshold associated with absolute phase values to determine the fringe order error, thus making it more reliable and avoiding the procedure of search in detecting and correcting successive fringe order errors. The effectiveness of the proposed method is validated by the experimental results.
Pfaff equation and Fourier analysis to phase extraction from an interferogram with carrier frequency
International Nuclear Information System (INIS)
Lara-Cortez, Francisco; Meneses-Fabian, Cruz; Rodriguez-Zurita, Gustavo
2011-01-01
In the phase extraction techniques, one of the steps most used is to calculate the phase unwrapping from the wrapped phase, which is generally obtained via the inverse tangent function. With the idea to avoid this process, in the present manuscript a method based in the solution of the Pfaff equations is proposed. It is shown that the Pfaff equation is formed with the phase gradient and an auxiliary vector. The phase gradient is obtained from an interference patron with carrier frequency by applying the Fourier transform method and the partial derivatives. In the present manuscript, mathematical analysis, numerical simulation, and the phase extraction of some experimental interferograms are shown.
Real-time quantitative phase reconstruction in off-axis digital holography using multiplexing.
Girshovitz, Pinhas; Shaked, Natan T
2014-04-15
We present a new approach for obtaining significant speedup in the digital processing of extracting unwrapped phase profiles from off-axis digital holograms. The new technique digitally multiplexes two orthogonal off-axis holograms, where the digital reconstruction, including spatial filtering and two-dimensional phase unwrapping on a decreased number of pixels, can be performed on both holograms together, without redundant operations. Using this technique, we were able to reconstruct, for the first time to our knowledge, unwrapped phase profiles from off-axis holograms with 1 megapixel in more than 30 frames per second using a standard single-core personal computer on a MATLAB platform, without using graphic-processing-unit programming or parallel computing. This new technique is important for real-time quantitative visualization and measurements of highly dynamic samples and is applicable for a wide range of applications, including rapid biological cell imaging and real-time nondestructive testing. After comparing the speedups obtained by the new technique for holograms of various sizes, we present experimental results of real-time quantitative phase visualization of cells flowing rapidly through a microchannel.
Schuler, Michael; Whitsitt, Seth; Henry, Louis-Paul; Sachdev, Subir; Läuchli, Andreas M
2016-11-18
The low-energy spectra of many body systems on a torus, of finite size L, are well understood in magnetically ordered and gapped topological phases. However, the spectra at quantum critical points separating such phases are largely unexplored for (2+1)D systems. Using a combination of analytical and numerical techniques, we accurately calculate and analyze the low-energy torus spectrum at an Ising critical point which provides a universal fingerprint of the underlying quantum field theory, with the energy levels given by universal numbers times 1/L. We highlight the implications of a neighboring topological phase on the spectrum by studying the Ising* transition (i.e. the transition between a Z_{2} topological phase and a trivial paramagnet), in the example of the toric code in a longitudinal field, and advocate a phenomenological picture that provides qualitative insight into the operator content of the critical field theory.
Phase gradient algorithm based on co-axis two-step phase-shifting interferometry and its application
Wang, Yawei; Zhu, Qiong; Xu, Yuanyuan; Xin, Zhiduo; Liu, Jingye
2017-12-01
A phase gradient method based on co-axis two-step phase-shifting interferometry, is used to reveal the detailed information of a specimen. In this method, the phase gradient distribution can only be obtained by calculating both the first-order derivative and the radial Hilbert transformation of the intensity difference between two phase-shifted interferograms. The feasibility and accuracy of this method were fully verified by the simulation results for a polystyrene sphere and a red blood cell. The empirical results demonstrated that phase gradient is sensitive to changes in the refractive index and morphology. Because phase retrieval and tedious phase unwrapping are not required, the calculation speed is faster. In addition, co-axis interferometry has high spatial resolution.
3D measurement using combined Gray code and dual-frequency phase-shifting approach
Yu, Shuang; Zhang, Jing; Yu, Xiaoyang; Sun, Xiaoming; Wu, Haibin; Liu, Xin
2018-04-01
The combined Gray code and phase-shifting approach is a commonly used 3D measurement technique. In this technique, an error that equals integer multiples of the phase-shifted fringe period, i.e. period jump error, often exists in the absolute analog code, which can lead to gross measurement errors. To overcome this problem, the present paper proposes 3D measurement using a combined Gray code and dual-frequency phase-shifting approach. Based on 3D measurement using the combined Gray code and phase-shifting approach, one set of low-frequency phase-shifted fringe patterns with an odd-numbered multiple of the original phase-shifted fringe period is added. Thus, the absolute analog code measured value can be obtained by the combined Gray code and phase-shifting approach, and the low-frequency absolute analog code measured value can also be obtained by adding low-frequency phase-shifted fringe patterns. Then, the corrected absolute analog code measured value can be obtained by correcting the former by the latter, and the period jump errors can be eliminated, resulting in reliable analog code unwrapping. For the proposed approach, we established its measurement model, analyzed its measurement principle, expounded the mechanism of eliminating period jump errors by error analysis, and determined its applicable conditions. Theoretical analysis and experimental results show that the proposed approach can effectively eliminate period jump errors, reliably perform analog code unwrapping, and improve the measurement accuracy.
Chiral anomalies in higher dimensional supersymmetric theories
International Nuclear Information System (INIS)
Bonora, L.; Pasti, P.; Tonin, M.
1987-01-01
We derive explicit formulas for pure gauge anomalies in a SYM theory in 6D as well as in 10D. Each anomaly consists of two terms: a gauge cocycle and a cocycle of the superdiffeomorphisms. The derivation is based essentially on a remarkable property of supersymmetric theories which we call Weil triviality and is directly connected with the constraints. The analogous problem for Lorentz anomalies is stated in the same way. However, in general, there are difficulties concerning Weil triviality. We prove that for pure SUGRA in 6D as well as in 10D it is possible to prove Weil triviality and, consequently, to obtain explict expressions for pure Lorentz anomalies. However, as far as SUGRA coupled to SYM a la Chapline-Manton or a la Green-Schwarz is concerned, no self-evident solution is available. (orig.)
Higher dimensional uniformisation and W-geometry
International Nuclear Information System (INIS)
Govindarajan, S.
1995-01-01
We formulate the uniformisation problem underlying the geometry of W n -gravity using the differential equation approach to W-algebras. We construct W n -space (analogous to superspace in supersymmetry) as an (n-1)-dimensional complex manifold using isomonodromic deformations of linear differential equations. The W n -manifold is obtained by the quotient of a Fuchsian subgroup of PSL(n,R) which acts properly discontinuously on a simply connected domain in bfCP n-1 . The requirement that a deformation be isomonodromic furnishes relations which enable one to convert non-linear W-diffeomorphisms to (linear) diffeomorphisms on the W n -manifold. We discuss how the Teichmueller spaces introduced by Hitchin can then be interpreted as the space of complex structures or the space of projective structures with real holonomy on the W n -manifold. The projective structures are characterised by Halphen invariants which are appropriate generalisations of the Schwarzian. This construction will work for all ''generic'' W-algebras. (orig.)
Higher-dimensional puncture initial data
International Nuclear Information System (INIS)
Zilhao, Miguel; Ansorg, Marcus; Cardoso, Vitor; Gualtieri, Leonardo; Herdeiro, Carlos; Sperhake, Ulrich; Witek, Helvi
2011-01-01
We calculate puncture initial data, corresponding to single and binary black holes with linear momenta, which solve the constraint equations of D-dimensional vacuum gravity. The data are generated by a modification of the pseudospectral code presented in [M. Ansorg, B. Bruegmann, and W. Tichy, Phys. Rev. D 70, 064011 (2004).] and made available as the TwoPunctures thorn inside the Cactus computational toolkit. As examples, we exhibit convergence plots, the violation of the Hamiltonian constraint as well as the initial data for D=4,5,6,7. These initial data are the starting point to perform high-energy collisions of black holes in D dimensions.
Higher dimensional supersymmetric quantum mechanics and Dirac ...
Indian Academy of Sciences (India)
We exhibit the supersymmetric quantum mechanical structure of the full 3+1 dimensional Dirac equation considering `mass' as a function of coordinates. Its usefulness in solving potential problems is discussed with speciﬁc examples. We also discuss the `physical' signiﬁcance of the supersymmetric states in this formalism.
Higher dimensional generalizations of the SYK model
Energy Technology Data Exchange (ETDEWEB)
Berkooz, Micha [Department of Particle Physics and Astrophysics, Weizmann Institute of Science,Rehovot 7610001 (Israel); Narayan, Prithvi [International Centre for Theoretical Sciences, Hesaraghatta,Bengaluru North, 560 089 (India); Rozali, Moshe [Department of Physics and Astronomy, University of British Columbia,Vancouver, BC V6T 1Z1 (Canada); Simón, Joan [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh,King’s Buildings, Edinburgh EH9 3FD (United Kingdom)
2017-01-31
We discuss a 1+1 dimensional generalization of the Sachdev-Ye-Kitaev model. The model contains N Majorana fermions at each lattice site with a nearest-neighbour hopping term. The SYK random interaction is restricted to low momentum fermions of definite chirality within each lattice site. This gives rise to an ordinary 1+1 field theory above some energy scale and a low energy SYK-like behavior. We exhibit a class of low-pass filters which give rise to a rich variety of hyperscaling behaviour in the IR. We also discuss another set of generalizations which describes probing an SYK system with an external fermion, together with the new scaling behavior they exhibit in the IR.
Full-Field Calibration of Color Camera Chromatic Aberration using Absolute Phase Maps.
Liu, Xiaohong; Huang, Shujun; Zhang, Zonghua; Gao, Feng; Jiang, Xiangqian
2017-05-06
The refractive index of a lens varies for different wavelengths of light, and thus the same incident light with different wavelengths has different outgoing light. This characteristic of lenses causes images captured by a color camera to display chromatic aberration (CA), which seriously reduces image quality. Based on an analysis of the distribution of CA, a full-field calibration method based on absolute phase maps is proposed in this paper. Red, green, and blue closed sinusoidal fringe patterns are generated, consecutively displayed on an LCD (liquid crystal display), and captured by a color camera from the front viewpoint. The phase information of each color fringe is obtained using a four-step phase-shifting algorithm and optimum fringe number selection method. CA causes the unwrapped phase of the three channels to differ. These pixel deviations can be computed by comparing the unwrapped phase data of the red, blue, and green channels in polar coordinates. CA calibration is accomplished in Cartesian coordinates. The systematic errors introduced by the LCD are analyzed and corrected. Simulated results show the validity of the proposed method and experimental results demonstrate that the proposed full-field calibration method based on absolute phase maps will be useful for practical software-based CA calibration.
Shifting of wrapped phase maps in the frequency domain using a rational number
International Nuclear Information System (INIS)
Gdeisat, Munther A; Abushakra, Ahmad; Qaddoura, Maen; Burton, David R; Lilley, Francis; Arevalillo-Herráez, Miguel
2016-01-01
The number of phase wraps in an image can be either reduced, or completely eliminated, by transforming the image into the frequency domain using a Fourier transform, and then shifting the spectrum towards the origin. After this, the spectrum is transformed back to the spatial domain using the inverse Fourier transform and finally the phase is extracted using the arctangent function. However, it is a common concern that the spectrum can be shifted only by an integer number, meaning that the phase wrap reduction is often not optimal. In this paper we propose an algorithm than enables the spectrum to be frequency shifted by a rational number. The principle of the proposed method is confirmed both by using an initial computer simulation and is subsequently validated experimentally on real fringe patterns. The technique may offer in some cases the prospects of removing the necessity for a phase unwrapping process altogether and/or speeding up the phase unwrapping process. This may be beneficial in terms of potential increases in signal recovery robustness and also for use in time-critical applications. (paper)
Unwrapping Students' Ideas about Fractions
Lewis, Rebecca M.; Gibbons, Lynsey K.; Kazemi, Elham; Lind, Teresa
2015-01-01
Supporting students to develop an understanding of the meaning of fractions is an important goal of elementary school mathematics. This involves developing partitioning strategies, creating representations, naming fractional quantities, and using symbolic notation. This article describes how teachers can use a formative assessment problem to…
Phase-preserved optical elevator.
Luo, Yuan; Zhang, Baile; Han, Tiancheng; Chen, Zhi; Duan, Yubo; Chu, Chia-Wei; Barbastathis, George; Qiu, Cheng Wei
2013-03-25
The unique superiority of transformation optics devices designed from coordinate transformation is their capability of recovering both ray trajectory and optical path length in light manipulation. However, very few experiments have been done so far to verify this dual-recovery property from viewpoints of both ray trajectory and optical path length simultaneously. The experimental difficulties arise from the fact that most previous optical transformation optics devices only work at the nano-scale; the lack of intercomparison between data from both optical path length and ray trajectory measurement in these experiments obscured the fact that the ray path was subject to a subwavelength lateral shift that was otherwise not easily perceivable and, instead, was pointed out theoretically [B. Zhang et al. Phys. Rev. Lett. 104, 233903, 2010]. Here, we use a simple macroscopic transformation optics device of phase-preserved optical elevator, which is a typical birefringent optical phenomenon that can virtually lift an optical image by a macroscopic distance, to demonstrate decisively the unique optical path length preservation property of transformation optics. The recovery of ray trajectory is first determined with no lateral shift in the reflected ray. The phase preservation is then verified with incoherent white-light interferometry without ambiguity and phase unwrapping.
Optimization of phase-variation measurements in low-coherence methods: implications for OCE
Zaitsev, Vladimir Y.; Matveyev, Alexandr L.; Matveev, Lev A.; Gelikonov, Grigory V.; Sovetsky, Alexander A.; Vitkin, Alex
2016-04-01
Phase-resolved measurements found numerous applications in low-coherence methods, in particular in OCT-based compressional elastography, where phase-variation gradients are used for estimating strains produced by the OCT probe pressed onto the tissue. Conventionally, for the reference and deformed pixelated OCT scans, one performs comparison of phases taken from pixels with the same coordinates. This is reasonable in regions of sufficiently small sub-pixel displacements, for which the so-compared pixels contain the same scatterers. Furthermore, to avoid error-prone multiple phase unwrapping for reconstructing displacements, one have to ensure even smaller sub-wavelength displacements. This limits the allowable strains to less than ~10-4-10-3, although such weak phase gradients can be strongly corrupted by measurement noises. Here, we discuss how creation of an order of magnitude greater strains can be used for increasing the signal-to noise ratio in estimating phase gradients by obviating the phase-unwrapping procedures and reducing the influence of decorrelation noise for supra-pixel displacements. This optimized phase-variation measurement makes it possible to perform strain mapping in optical coherence elastography with exceptionally high tolerance to noises due to possibility of using significantly increased strains. We also discuss the effect of "frozen-phase zones" associated with displaced strong scatterers. This effect can result in appearance of artifacts in the form of false stiff inclusions in elastograms in the vicinity of bright scatterers in OCT scans. We present analytical arguments, numerical simulations and experimental examples illustrating the above-mentioned features of the "frozen-phase" effect and advantages of using the proposed optimized phase-variation measurement with pixel-scale displacement compensation in the compared OCT scans.
Lu, Jin; Mo, Rong; Sun, Huibin; Chang, Zhiyong; Zhao, Xiaxia
2016-04-01
In fringe projection profilometry, a simplified method is proposed to recover absolute phase maps of two-frequency fringe patterns by using a unique mapping rule. The mapping rule is designed from the rounded phase values to the fringe order of each pixel. Absolute phase can be recovered by the fringe order maps. Unlike the existing techniques, where the lowest frequency of dual- or multiple-frequency fringe patterns must be single, the presented method breaks the limitation and simplifies the procedure of phase unwrapping. Additionally, due to many issues including ambient light, shadow, sharp edges, step height boundaries and surface reflectivity variations, a novel framework of automatically identifying and removing invalid phase values is also proposed. Simulations and experiments have been carried out to validate the performances of the proposed method.
Extended Kalman filtering for joint mitigation of phase and amplitude noise in coherent QAM systems.
Pakala, Lalitha; Schmauss, Bernhard
2016-03-21
We numerically investigate our proposed carrier phase and amplitude noise estimation (CPANE) algorithm using extend Kalman filter (EKF) for joint mitigation of linear and non-linear phase noise as well as amplitude noise on 4, 16 and 64 polarization multiplexed (PM) quadrature amplitude modulation (QAM) 224 Gb/s systems. The results are compared to decision directed (DD) carrier phase estimation (CPE), DD phase locked loop (PLL) and universal CPE (U-CPE) algorithms. Besides eliminating the necessity of phase unwrapping function, EKF-CPANE shows improved performance for both back-to-back (BTB) and transmission scenarios compared to the aforementioned algorithms. We further propose a weighted innovation approach (WIA) of the EKF-CPANE which gives an improvement of 0.3 dB in the Q-factor, compared to the original algorithm.
Stabilization of compactification volume in a noncommutative mini-super-phase-space
International Nuclear Information System (INIS)
Khosravi, N.; Sepangi, H.R.; Sheikh-Jabbari, M.M.
2007-01-01
We consider a class of generalized FRW type metrics in the context of higher dimensional Einstein gravity in which the extra dimensions are allowed to have different scale factors. It is shown that noncommutativity between the momenta conjugate to the internal space scale factors controls the power-law behavior of the scale factors in the extra dimensions, taming it to an oscillatory behavior. Hence noncommutativity among the internal momenta of the mini-super-phase-space can be used to explain stabilization of the compactification volume of the internal space in a higher dimensional gravity theory
Jiang, Hongzhi; Zhao, Huijie; Li, Xudong; Quan, Chenggen
2016-03-07
We propose a novel hyper thin 3D edge measurement technique to measure the profile of 3D outer envelope of honeycomb core structures. The width of the edges of the honeycomb core is less than 0.1 mm. We introduce a triangular layout design consisting of two cameras and one projector to measure hyper thin 3D edges and eliminate data interference from the walls. A phase-shifting algorithm and the multi-frequency heterodyne phase-unwrapping principle are applied for phase retrievals on edges. A new stereo matching method based on phase mapping and epipolar constraint is presented to solve correspondence searching on the edges and remove false matches resulting in 3D outliers. Experimental results demonstrate the effectiveness of the proposed method for measuring the 3D profile of honeycomb core structures.
Wilson loop's phase transition probed by non-local observable
Directory of Open Access Journals (Sweden)
Hui-Ling Li
2018-04-01
Full Text Available In order to give further insights into the holographic Van der Waals phase transition, it would be of great interest to investigate the behavior of Wilson loop across the holographic phase transition for a higher dimensional hairy black hole. We offer a possibility to proceed with a numerical calculation in order to discussion on the hairy black hole's phase transition, and show that Wilson loop can serve as a probe to detect a phase structure of the black hole. Furthermore, for a first order phase transition, we calculate numerically the Maxwell's equal area construction; and for a second order phase transition, we also study the critical exponent in order to characterize the Wilson loop's phase transition.
Absolute phase map recovery of two fringe patterns with flexible selection of fringe wavelengths.
Long, Jiale; Xi, Jiangtao; Zhu, Ming; Cheng, Wenqing; Cheng, Rui; Li, Zhongwei; Shi, Yusheng
2014-03-20
A novel approach is proposed to unwrap the phase maps of two fringe patterns in fringe pattern projection-based profilometry. In contrast to existing techniques, where spatial frequencies (i.e., the number of fringes on a pattern) of the two fringe patterns must be integers and coprime, the proposed method is applicable for any two fringe patterns with different fringe wavelengths (i.e., the number of pixels in a fringe) and thus provides more flexibility in the use of fringe patterns. Moreover, compared to the existing techniques, the proposed method is simpler in its implementation and has better antierror capability. Theoretical analysis and experiment results are presented to confirm the effectiveness of the proposed method.
Li, Minkang; Zhou, Changhe; Wei, Chunlong; Jia, Wei; Lu, Yancong; Xiang, Changcheng; Xiang, XianSong
2016-10-01
Large-sized gratings are essential optical elements in laser fusion and space astronomy facilities. Scanning beam interference lithography is an effective method to fabricate large-sized gratings. To minimize the nonlinear phase written into the photo-resist, the image grating must be measured to adjust the left and right beams to interfere at their waists. In this paper, we propose a new method to conduct wavefront metrology based on phase-stepping interferometry. Firstly, a transmission grating is used to combine the two beams to form an interferogram which is recorded by a charge coupled device(CCD). Phase steps are introduced by moving the grating with a linear stage monitored by a laser interferometer. A series of interferograms are recorded as the displacement is measured by the laser interferometer. Secondly, to eliminate the tilt and piston error during the phase stepping, the iterative least square phase shift method is implemented to obtain the wrapped phase. Thirdly, we use the discrete cosine transform least square method to unwrap the phase map. Experiment results indicate that the measured wavefront has a nonlinear phase around 0.05 λ@404.7nm. Finally, as the image grating is acquired, we simulate the print-error written into the photo-resist.
Lepton electric dipole moments, supersymmetric seesaw, and leptogenesis phase
International Nuclear Information System (INIS)
Dutta, Bhaskar; Mohapatra, R.N.
2003-01-01
We calculate the lepton electric dipole moments in a class of supersymmetric seesaw models and explore the possibility that they may provide a way to probe some of the CP violating phases responsible for the origin of matter via leptogenesis. We show that in models where the right handed neutrino masses M R arise from the breaking of local B-L by a Higgs field with B-L=2, some of the leptogenesis phases can lead to enhancement of the lepton dipole moments compared to the prediction of models where M R is either directly put in by hand or is a consequence of a higher dimensional operator
The Peierls argument for higher dimensional Ising models
International Nuclear Information System (INIS)
Bonati, Claudio
2014-01-01
The Peierls argument is a mathematically rigorous and intuitive method to show the presence of a non-vanishing spontaneous magnetization in some lattice models. This argument is typically explained for the D = 2 Ising model in a way which cannot be easily generalized to higher dimensions. The aim of this paper is to present an elementary discussion of the Peierls argument for the general D-dimensional Ising model. (paper)
Geometry of higher-dimensional black hole thermodynamics
International Nuclear Information System (INIS)
Aaman, Jan E.; Pidokrajt, Narit
2006-01-01
We investigate thermodynamic curvatures of the Kerr and Reissner-Nordstroem (RN) black holes in spacetime dimensions higher than four. These black holes possess thermodynamic geometries similar to those in four-dimensional spacetime. The thermodynamic geometries are the Ruppeiner geometry and the conformally related Weinhold geometry. The Ruppeiner geometry for a d=5 Kerr black hole is curved and divergent in the extremal limit. For a d≥6 Kerr black hole there is no extremality but the Ruppeiner curvature diverges where one suspects that the black hole becomes unstable. The Weinhold geometry of the Kerr black hole in arbitrary dimension is a flat geometry. For the RN black hole the Ruppeiner geometry is flat in all spacetime dimensions, whereas its Weinhold geometry is curved. In d≥5 the Kerr black hole can possess more than one angular momentum. Finally we discuss the Ruppeiner geometry for the Kerr black hole in d=5 with double angular momenta
Higher-dimensional cosmological model with variable gravitational ...
Indian Academy of Sciences (India)
We have studied five-dimensional homogeneous cosmological models with variable and bulk viscosity in Lyra geometry. Exact solutions for the field equations have been obtained and physical properties of the models are discussed. It has been observed that the results of new models are well within the observational ...
Light higgsinos as heralds of higher-dimensional unification
International Nuclear Information System (INIS)
Bruemmer, F.; Buchmueller, W.
2011-05-01
Grand-unified models with extra dimensions at the GUT scale will typically contain exotic states with Standard Model charges and GUT-scale masses. They can act as messengers for gauge-mediated supersymmetry breaking. If the number of messengers is sizeable, soft terms for the visible sector fields will be predominantly generated by gauge mediation, while gravity mediation can induce a small μ parameter. We illustrate this hybrid mediation pattern with two examples, in which the superpartner spectrum contains light and near-degenerate higgsinos with masses below 200 GeV. The typical masses of all other superpartners are much larger, from at least 500 GeV up to several TeV. The lightest superparticle is the gravitino, which may be the dominant component of dark matter. (orig.)
Gravitational collapse in higher-dimensional charged-Vaidya space ...
Indian Academy of Sciences (India)
time. We show that singularities arising in a charged null fluid in higher dimension are always naked violating ... of matter is one of the most active field of research in the contemporary general relativity. ... The main open issue ..... [3] A Papapetrou, in A random walk in relativity and cosmology edited by N Dadhich, J K Rao,.
Euclidean D-branes and higher-dimensional gauge theory
International Nuclear Information System (INIS)
Acharya, B.S.; Figueroa-O'Farrill, J.M.; Spence, B.; O'Loughlin, M.
1997-07-01
We consider euclidean D-branes wrapping around manifolds of exceptional holonomy in dimensions seven and eight. The resulting theory on the D-brane-that is, the dimensional reduction of 10-dimensional supersymmetric Yang-Mills theory-is a cohomological field theory which describes the topology of the moduli space of instantons. The 7-dimensional theory is an N T =2 (or balanced) cohomological theory given by an action potential of Chern-Simons type. As a by-product of this method, we construct a related cohomological field theory which describes the monopole moduli space on a 7-manifold of G 2 holonomy. (author). 22 refs, 3 tabs
Exploring Higher Dimensional Black Holes at the Large Hadron Collider
Harris, C M; Parker, M A; Richardson, P; Sabetfakhri, A; Webber, Bryan R
2005-01-01
In some extra dimension theories with a TeV fundamental Planck scale, black holes could be produced in future collider experiments. Although cross sections can be large, measuring the model parameters is difficult due to the many theoretical uncertainties. Here we discuss those uncertainties and then we study the experimental characteristics of black hole production and decay at a typical detector using the ATLAS detector as a guide. We present a new technique for measuring the temperature of black holes that applies to many models. We apply this technique to a test case with four extra dimensions and, using an estimate of the parton-level production cross section error of 20\\%, determine the Planck mass to 15\\% and the number of extra dimensions to $\\pm$0.75.
Exploring higher dimensional black holes at the Large Hadron Collider
International Nuclear Information System (INIS)
Harris, Christopher M.; Palmer, Matthew J.; Parker, Michael A.; Richardson, Peter; Sabetfakhri, Ali; Webber, Bryan R.
2005-01-01
In some extra dimension theories with a TeV fundamental Planck scale, black holes could be produced in future collider experiments. Although cross sections can be large, measuring the model parameters is difficult due to the many theoretical uncertainties. Here we discuss those uncertainties and then we study the experimental characteristics of black hole production and decay at a typical detector using the ATLAS detector as a guide. We present a new technique for measuring the temperature of black holes that applies to many models. We apply this technique to a test case with four extra dimensions and, using an estimate of the parton-level production cross section error of 20%, determine the Planck mass to 15% and the number of extra dimensions to ±0.75
Application of Quantum Process Calculus to Higher Dimensional Quantum Protocols
Directory of Open Access Journals (Sweden)
Simon J. Gay
2014-07-01
Full Text Available We describe the use of quantum process calculus to describe and analyze quantum communication protocols, following the successful field of formal methods from classical computer science. We have extended the quantum process calculus to describe d-dimensional quantum systems, which has not been done before. We summarise the necessary theory in the generalisation of quantum gates and Bell states and use the theory to apply the quantum process calculus CQP to quantum protocols, namely qudit teleportation and superdense coding.
Higher-dimensional string theory in Lyra geometry
Indian Academy of Sciences (India)
Cosmic strings as source of gravitational field in general relativity was discussed by ... tensor theory of gravitation and constructed an analog of Einstein field ... As string concept is useful before the particle creation and can explain galaxy for-.
Conductivity of higher dimensional holographic superconductors with nonlinear electrodynamics
Sheykhi, Ahmad; Hashemi Asl, Doa; Dehyadegari, Amin
2018-06-01
We investigate analytically as well as numerically the properties of s-wave holographic superconductors in d-dimensional spacetime and in the presence of Logarithmic nonlinear electrodynamics. We study three aspects of this kind of superconductors. First, we obtain, by employing analytical Sturm-Liouville method as well as numerical shooting method, the relation between critical temperature and charge density, ρ, and disclose the effects of both nonlinear parameter b and the dimensions of spacetime, d, on the critical temperature Tc. We find that in each dimension, Tc /ρ 1 / (d - 2) decreases with increasing the nonlinear parameter b while it increases with increasing the dimension of spacetime for a fixed value of b. Then, we calculate the condensation value and critical exponent of the system analytically and numerically and observe that in each dimension, the dimensionless condensation get larger with increasing the nonlinear parameter b. Besides, for a fixed value of b, it increases with increasing the spacetime dimension. We confirm that the results obtained from our analytical method are in agreement with the results obtained from numerical shooting method. This fact further supports the correctness of our analytical method. Finally, we explore the holographic conductivity of this system and find out that the superconducting gap increases with increasing either the nonlinear parameter or the spacetime dimension.
Higher-dimensional bosonization and its application to Fermi liquids
Energy Technology Data Exchange (ETDEWEB)
Meier, Hendrik
2012-06-28
The bosonization scheme presented in this thesis allows to map models of interacting fermions onto equivalent models describing collective bosonic excitations. For simple systems that do not require plenty computational power and optimized algorithms, the positivity of the weight function in the bosonic frame has been confirmed - in particular also for those configurations in which the fermionic representation shows the minus-sign problem. The numerical tests are absolutely elementary and based on the simplest possible regularization scheme. The second part of this thesis presented an analytical study about the non-analytic corrections to thermodynamic quantities in a two-dimensional Fermi liquid. The perturbation theory developed for the exact formulation is by no means more convenient than the well-established fermionic diagram technique. The effective low-energy theory for studying the anomalous contributions to the Fermi liquid was derived focussing on the relevant soft modes of the interaction only. The final effective model took the form of a field theory for a bosonic superfield Ψ interacting in quadratic, cubic, and quartic terms in the action. This field theory turned out nontrivial and was shown to lead to logarithmic divergencies in both spin and charge channels. By means of a combined scheme of ladder diagram summations and renormalization group equations, the logarithmic terms were summed up in the first-loop order, thus yielding the renormalized effective coupling constants of the theory at low temperatures. The fully renormalized action then allowed to conveniently compute the low-temperature limit behavior of the non-analytic corrections to the Fermi-liquid thermodynamic response functions such as the low temperature non-analytic correction δc to the specific heat. The explicit formula for δc is the sum of two contributions - one due to the spin singlet and one due to the spin triplet superconducting excitations. Depending on the values of the bare coupling constants, the system may be driven toward an instability at a sufficiently low temperature. Furthermore, the result shows that also certain variations of repulsive interaction flow toward an instability: Specifically in models with a large 2p{sub F}-scattering amplitude, the Fermi-liquid picture breaks down at a critical temperature T{sub c} and a transition to triplet Cooper pairing similar to the Kohn-Luttinger scenario occurs.
Higher-dimensional cosmological model with variable gravitational ...
Indian Academy of Sciences (India)
variable G and bulk viscosity in Lyra geometry. Exact solutions for ... a comparative study of Robertson–Walker models with a constant deceleration .... where H is defined as H =(˙A/A)+(1/3)( ˙B/B) and β0,H0 are representing present values of β ...
GUT precursors and fixed points in higher-dimensional theories
Indian Academy of Sciences (India)
that it is possible to construct self-consistent 'hybrid' models containing ... states associated with the emergence of a grand unified theory (GUT) at this en- .... However, even though these couplings are extremely weak, the true loop expansion.
Simplicial models for trace spaces II: General higher dimensional automata
DEFF Research Database (Denmark)
Raussen, Martin
of directed paths with given end points in a pre-cubical complex as the nerve of a particular category. The paper generalizes the results from Raussen [19, 18] in which we had to assume that the HDA in question arises from a semaphore model. In particular, important for applications, it allows for models...
Static wormhole solution for higher-dimensional gravity in vacuum
International Nuclear Information System (INIS)
Dotti, Gustavo; Oliva, Julio; Troncoso, Ricardo
2007-01-01
A static wormhole solution for gravity in vacuum is found for odd dimensions greater than four. In five dimensions the gravitational theory considered is described by the Einstein-Gauss-Bonnet action where the coupling of the quadratic term is fixed in terms of the cosmological constant. In higher dimensions d=2n+1, the theory corresponds to a particular case of the Lovelock action containing higher powers of the curvature, so that in general, it can be written as a Chern-Simons form for the AdS group. The wormhole connects two asymptotically locally AdS spacetimes each with a geometry at the boundary locally given by RxS 1 xH d-3 . Gravity pulls towards a fixed hypersurface located at some arbitrary proper distance parallel to the neck. The causal structure shows that both asymptotic regions are connected by light signals in a finite time. The Euclidean continuation of the wormhole is smooth independently of the Euclidean time period, and it can be seen as instanton with vanishing Euclidean action. The mass can also be obtained from a surface integral and it is shown to vanish
Casimir energy and the possibility of higher dimensional manipulation
Obousy, R. K.; Saharian, A. A.
2009-01-01
It is well known that the Casimir effect is an excellent candidate for the stabilization of the extra dimensions. It has also been suggested that the Casimir effect in higher dimensions may be the underlying phenomenon that is responsible for the dark energy which is currently driving the accelerated expansion of the universe. In this paper we suggest that, in principle, it may be possible to directly manipulate the size of an extra dimension locally using Standard Model fields in the next ge...
Higher dimensional unitary braid matrices: Construction, associated structures and entanglements
International Nuclear Information System (INIS)
Abdesselam, B.; Chakrabarti, A.; Dobrev, V.K.; Mihov, S.G.
2007-03-01
We construct (2n) 2 x (2n) 2 unitary braid matrices R-circumflex for n ≥ 2 generalizing the class known for n = 1. A set of (2n) x (2n) matrices (I, J,K,L) are defined. R-circumflex is expressed in terms of their tensor products (such as K x J), leading to a canonical formulation for all n. Complex projectors P ± provide a basis for our real, unitary R-circumflex. Baxterization is obtained. Diagonalizations and block- diagonalizations are presented. The loss of braid property when R-circumflex (n > 1) is block-diagonalized in terms of R-circumflex (n = 1) is pointed out and explained. For odd dimension (2n + 1) 2 x (2n + 1) 2 , a previously constructed braid matrix is complexified to obtain unitarity. R-circumflexLL- and R-circumflexTT- algebras, chain Hamiltonians, potentials for factorizable S-matrices, complex non-commutative spaces are all studied briefly in the context of our unitary braid matrices. Turaev construction of link invariants is formulated for our case. We conclude with comments concerning entanglements. (author)
Light higgsinos as heralds of higher-dimensional unification
Energy Technology Data Exchange (ETDEWEB)
Bruemmer, F.; Buchmueller, W.
2011-05-15
Grand-unified models with extra dimensions at the GUT scale will typically contain exotic states with Standard Model charges and GUT-scale masses. They can act as messengers for gauge-mediated supersymmetry breaking. If the number of messengers is sizeable, soft terms for the visible sector fields will be predominantly generated by gauge mediation, while gravity mediation can induce a small {mu} parameter. We illustrate this hybrid mediation pattern with two examples, in which the superpartner spectrum contains light and near-degenerate higgsinos with masses below 200 GeV. The typical masses of all other superpartners are much larger, from at least 500 GeV up to several TeV. The lightest superparticle is the gravitino, which may be the dominant component of dark matter. (orig.)
Instability of higher dimensional Yang-Mills systems
International Nuclear Information System (INIS)
Randjbar-Daemi, S.; Strathdee, J.
1983-01-01
We investigate the stability of Poincare xO(3) invariant solutions for a pure semi-simple Yang-Mills, as well as Yang-Mills coupled to gravity in 6-dimensional space-time compactified over M 4 xS 2 . In contrast to the Maxwell U(1) theory (IC-82/208) in six dimensions coupled with gravity and investigated previously, the present theory exhibits tachyonic excitations and is unstable. (author)
Massive Higher Dimensional Gauge Fields as Messengers of Supersymmetry Breaking
International Nuclear Information System (INIS)
Chacko, Z.; Luty, Markus A.; Ponton, Eduardo
2000-01-01
We consider theories with one or more compact dimensions with size r > 1/M, where M is the fundamental Planck scale, with the visible and hidden sectors localized on spatially separated 3 -branes''. We show that a bulk U(1) gauge field spontaneously broken on the hidden-sector 3-brane is an attractive candidate for the messenger of supersymmetry breaking. In this scenario scalar mass-squared terms are proportional to U(1) charges, and therefore naturally conserve flavor. Arbitrary flavor violation at the Planck scale gives rise to exponentially suppressed flavor violation at low energies. Gaugino masses can be generated if the standard gauge fields propagate in the bulk; μ and Bμ terms can be generated by the Giudice-Masiero or by the VEV of a singlet in the visible sector. The latter case naturally solves the SUSY CP problem. Realistic phenomenology can be obtained either if all microscopic parameters are order one in units of M, or if the theory is strongly coupled at the scale M. (For the latter case, we estimate parameters by extending n aive dimensional analysis'' to higher-dimension theories with branes.) In either case, the only unexplained hierarchy is the l arge'' size of the extra dimensions in fundamental units, which need only be an order of magnitude. All soft masses are naturally within an order of magnitude of m 3/2 , and trilinear scalar couplings are negligible. Squark and slepton masses can naturally unify even in the absence of grand unification. (author)
Higher Dimensional Mappings for Which the Area Formula Holds
Goffman, Casper; Ziemer, William P.
1970-01-01
For each continuous mapping of 2 space into n space, n ≥ 2, the Lebesgue area is given by the classical formula provided that the partial derivatives exist almost everywhere and belong to the class L2. The analogous question for mappings of m space into n space, 2 < m ≤ n, has been open for a long time. We answer this question in the affirmative in a more general setting. Accordingly, as a special case, we show that if a continuous mapping of m space into n space, m ≤ n, has partial derivatives which belong to Lm then the Lebesgue area is given by the classical formula. PMID:16591817
Charged fluid distribution in higher dimensional spheroidal space-time
Indian Academy of Sciences (India)
associated 3-spaces obtained as hypersurfaces t = constant, 3-spheroids, are suit- ... pressure. Considering the Vaidya–Tikekar [12] spheroidal geometry, ... a relativistic star in hydrostatic equilibrium having the spheroidal geometry of the .... K = 1, the spheroidal 3-space degenerates into a flat 3-space and when K = 0 it.
Kulkarni, Rishikesh; Rastogi, Pramod
2018-05-01
A new approach is proposed for the multiple phase estimation from a multicomponent exponential phase signal recorded in multi-beam digital holographic interferometry. It is capable of providing multidimensional measurements in a simultaneous manner from a single recording of the exponential phase signal encoding multiple phases. Each phase within a small window around each pixel is appproximated with a first order polynomial function of spatial coordinates. The problem of accurate estimation of polynomial coefficients, and in turn the unwrapped phases, is formulated as a state space analysis wherein the coefficients and signal amplitudes are set as the elements of a state vector. The state estimation is performed using the extended Kalman filter. An amplitude discrimination criterion is utilized in order to unambiguously estimate the coefficients associated with the individual signal components. The performance of proposed method is stable over a wide range of the ratio of signal amplitudes. The pixelwise phase estimation approach of the proposed method allows it to handle the fringe patterns that may contain invalid regions.
Unwrapping Court-Connected Mediation Agreements
DEFF Research Database (Denmark)
Adrian, Lin; Mykland, Solfrid
2018-01-01
Court-connected mediated agreements seem to both fulfil and fail the ideal of self-determination in mediation theory. In a study of 134 agreements from court-connected mediation, we found that the majority of agreements contain creative elements and display great variation in the provisions...... and understand them. The judicial language is well known for the drafters of the agreement but not the parties. Thus, court-connected mediation seems to fail aspects of self-determination when it comes to drafting agreements. We draw on new-institutional theory when we explore and explain this apparent...... they contain. These results indicate that the parties play an important role in crafting the substance of their agreements. However, we also found that the wording of the agreements is characterised by legal and bureaucratic language to the extent that people without legal training find it difficult to read...
New phases of D≥2 current and diffeomorphism algebras in particle physics
International Nuclear Information System (INIS)
Tze, Chia-Hsiung.
1990-09-01
We survey some global results and open issues of current algebras and their canonical field theoretical realization in D ≥ 2 dimensional spacetime. We assess the status of the representation theory of their generalized Kac-Moody and diffeomorphism algebras. Particular emphasis is put on higher dimensional analogs of fermi-bose correspondence, complex analyticity and the phase entanglements of anyonic solitons with exotic spin and statistics. 101 refs
New phases of D ge 2 current and diffeomorphism algebras in particle physics
Energy Technology Data Exchange (ETDEWEB)
Tze, Chia-Hsiung.
1990-09-01
We survey some global results and open issues of current algebras and their canonical field theoretical realization in D {ge} 2 dimensional spacetime. We assess the status of the representation theory of their generalized Kac-Moody and diffeomorphism algebras. Particular emphasis is put on higher dimensional analogs of fermi-bose correspondence, complex analyticity and the phase entanglements of anyonic solitons with exotic spin and statistics. 101 refs.
String-net condensation: A physical mechanism for topological phases
International Nuclear Information System (INIS)
Levin, Michael A.; Wen Xiaogang
2005-01-01
We show that quantum systems of extended objects naturally give rise to a large class of exotic phases--namely topological phases. These phases occur when extended objects, called ''string-nets,'' become highly fluctuating and condense. We construct a large class of exactly soluble 2D spin Hamiltonians whose ground states are string-net condensed. Each ground state corresponds to a different parity invariant topological phase. The models reveal the mathematical framework underlying topological phases: tensor category theory. One of the Hamiltonians--a spin-1/2 system on the honeycomb lattice--is a simple theoretical realization of a universal fault tolerant quantum computer. The higher dimensional case also yields an interesting result: we find that 3D string-net condensation naturally gives rise to both emergent gauge bosons and emergent fermions. Thus, string-net condensation provides a mechanism for unifying gauge bosons and fermions in 3 and higher dimensions
Vector method for strain estimation in phase-sensitive optical coherence elastography
Matveyev, A. L.; Matveev, L. A.; Sovetsky, A. A.; Gelikonov, G. V.; Moiseev, A. A.; Zaitsev, V. Y.
2018-06-01
A noise-tolerant approach to strain estimation in phase-sensitive optical coherence elastography, robust to decorrelation distortions, is discussed. The method is based on evaluation of interframe phase-variation gradient, but its main feature is that the phase is singled out at the very last step of the gradient estimation. All intermediate steps operate with complex-valued optical coherence tomography (OCT) signals represented as vectors in the complex plane (hence, we call this approach the ‘vector’ method). In comparison with such a popular method as least-square fitting of the phase-difference slope over a selected region (even in the improved variant with amplitude weighting for suppressing small-amplitude noisy pixels), the vector approach demonstrates superior tolerance to both additive noise in the receiving system and speckle-decorrelation caused by tissue straining. Another advantage of the vector approach is that it obviates the usual necessity of error-prone phase unwrapping. Here, special attention is paid to modifications of the vector method that make it especially suitable for processing deformations with significant lateral inhomogeneity, which often occur in real situations. The method’s advantages are demonstrated using both simulated and real OCT scans obtained during reshaping of a collagenous tissue sample irradiated by an IR laser beam producing complex spatially inhomogeneous deformations.
Energy Technology Data Exchange (ETDEWEB)
Li, Hui-Ling, E-mail: LHL51759@126.com [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); College of Physics Science and Technology, Shenyang Normal University, Shenyang 110034 (China); Yang, Shu-Zheng, E-mail: szyangcwnu@126.com [Institute of Theoretical Physics, China West Normal University, Nanchong 637002 (China); Zu, Xiao-Tao, E-mail: xtzu@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China)
2017-01-10
In the framework of holography, we survey the phase structure for a higher dimensional hairy black hole including the effects of the scalar field hair. It is worth emphasizing that, not only black hole entropy, but also entanglement entropy and two point correlation function exhibit the Van der Waals-like phase transition in a fixed scalar charge ensemble. Furthermore, by making use of numerical computation, we show that the Maxwell's equal area law is valid for the first order phase transition. In addition, we also discuss how the hair parameter affects the black hole's phase transition.
Application of Phase Shifted, Laser Feedback Interferometry to Fluid Physics
Ovryn, Ben; Eppell, Steven J.; Andrews, James H.; Khaydarov, John
1996-01-01
We have combined the principles of phase-shifting interferometry (PSI) and laser-feedback interferometry (LFI) to produce a new instrument that can measure both optical path length (OPL) changes and discern sample reflectivity variations. In LFI, coherent feedback of the incident light either reflected directly from a surface or reflected after transmission through a region of interest will modulate the output intensity of the laser. LFI can yield a high signal-to-noise ratio even for low reflectivity samples. By combining PSI and LFI, we have produced a robust instrument, based upon a HeNe laser, with high dynamic range that can be used to measure either static (dc) or oscillatory changes along the optical path. As with other forms of interferometry, large changes in OPL require phase unwrapping. Conversely, small phase changes are limited by the fraction of a fringe that can be measured. We introduce the phase shifts with an electro-optic modulator (EOM) and use either the Carre or Hariharan algorithms to determine the phase and visibility. We have determined the accuracy and precision of our technique by measuring both the bending of a cantilevered piezoelectric bimorph and linear ramps to the EOM. Using PSI, sub-nanometer displacements can be measured. We have combined our interferometer with a commercial microscope and scanning piezoelectric stage and have measured the variation in OPL and visibility for drops of PDMS (silicone oil) on coated single crystal silicon. Our measurement of the static contact angle agrees with the value of 68 deg stated in the literature.
A self-reference PRF-shift MR thermometry method utilizing the phase gradient
International Nuclear Information System (INIS)
Langley, Jason; Potter, William; Phipps, Corey; Zhao Qun; Huang Feng
2011-01-01
In magnetic resonance (MR) imaging, the most widely used and accurate method for measuring temperature is based on the shift in proton resonance frequency (PRF). However, inter-scan motion and bulk magnetic field shifts can lead to inaccurate temperature measurements in the PRF-shift MR thermometry method. The self-reference PRF-shift MR thermometry method was introduced to overcome such problems by deriving a reference image from the heated or treated image, and approximates the reference phase map with low-order polynomial functions. In this note, a new approach is presented to calculate the baseline phase map in self-reference PRF-shift MR thermometry. The proposed method utilizes the phase gradient to remove the phase unwrapping step inherent to other self-reference PRF-shift MR thermometry methods. The performance of the proposed method was evaluated using numerical simulations with temperature distributions following a two-dimensional Gaussian function as well as phantom and in vivo experimental data sets. The results from both the numerical simulations and experimental data show that the proposed method is a promising technique for measuring temperature. (note)
Canonical Entropy and Phase Transition of Rotating Black Hole
International Nuclear Information System (INIS)
Ren, Zhao; Yue-Qin, Wu; Li-Chun, Zhang
2008-01-01
Recently, the Hawking radiation of a black hole has been studied using the tunnel effect method. The radiation spectrum of a black hole is derived. By discussing the correction to spectrum of the rotating black hole, we obtain the canonical entropy. The derived canonical entropy is equal to the sum of Bekenstein–Hawking entropy and correction term. The correction term near the critical point is different from the one near others. This difference plays an important role in studying the phase transition of the black hole. The black hole thermal capacity diverges at the critical point. However, the canonical entropy is not a complex number at this point. Thus we think that the phase transition created by this critical point is the second order phase transition. The discussed black hole is a five-dimensional Kerr-AdS black hole. We provide a basis for discussing thermodynamic properties of a higher-dimensional rotating black hole. (general)
Transportable and vibration-free full-field low-coherent quantitative phase microscope
Yamauchi, Toyohiko; Yamada, Hidenao; Goto, Kentaro; Matsui, Hisayuki; Yasuhiko, Osamu; Ueda, Yukio
2018-02-01
We developed a transportable Linnik-type full-field low-coherent quantitative phase microscope that is able to compensate for optical path length (OPL) disturbance due to environmental mechanical noises. Though two-beam interferometers such as Linnik ones suffer from unstable OPL difference, we overcame this problem with a mechanical feedback system based on digital signal-processing that controls the OPL difference in sub-nanometer resolution precisely with a feedback bandwidth of 4 kHz. The developed setup has a footprint of 200 mm by 200 mm, a height of 500 mm, and a weight of 4.5 kilograms. In the transmission imaging mode, cells were cultured on a reflection-enhanced glass-bottom dish, and we obtained interference images sequentially while performing stepwise quarter-wavelength phase-shifting. Real-time image processing, including retrieval of the unwrapped phase from interference images and its background correction, along with the acquisition of interference images, was performed on a laptop computer. Emulation of the phase contrast (PhC) images and the differential interference contrast (DIC) images was also performed in real time. Moreover, our setup was applied for full-field cell membrane imaging in the reflection mode, where the cells were cultured on an anti-reflection (AR)-coated glass-bottom dish. The phase and intensity of the light reflected by the membrane revealed the outer shape of the cells independent of the refractive index. In this paper, we show imaging results on cultured cells in both transmission and reflection modes.
Sole, Ricard V; Solé, Ricard V; SolÃ©, Ricard V; Sol, Ricard V; Solé, Ricard V
2011-01-01
Phase transitions--changes between different states of organization in a complex system--have long helped to explain physics concepts, such as why water freezes into a solid or boils to become a gas. How might phase transitions shed light on important problems in biological and ecological complex systems? Exploring the origins and implications of sudden changes in nature and society, Phase Transitions examines different dynamical behaviors in a broad range of complex systems. Using a compelling set of examples, from gene networks and ant colonies to human language and the degradation of diverse ecosystems, the book illustrates the power of simple models to reveal how phase transitions occur. Introductory chapters provide the critical concepts and the simplest mathematical techniques required to study phase transitions. In a series of example-driven chapters, Ricard Solé shows how such concepts and techniques can be applied to the analysis and prediction of complex system behavior, including the origins of ...
Gilbert, Guillaume; Savard, Geneviève; Bard, Céline; Beaudoin, Gilles
2012-06-01
The aim of this study was to investigate the benefits arising from the use of a multiecho sequence for susceptibility-weighted phase imaging using a quantitative comparison with a standard single-echo acquisition. Four healthy adult volunteers were imaged on a clinical 3-T system using a protocol comprising two different three-dimensional susceptibility-weighted gradient-echo sequences: a standard single-echo sequence and a multiecho sequence. Both sequences were repeated twice in order to evaluate the local noise contribution by a subtraction of the two acquisitions. For the multiecho sequence, the phase information from each echo was independently unwrapped, and the background field contribution was removed using either homodyne filtering or the projection onto dipole fields method. The phase information from all echoes was then combined using a weighted linear regression. R2 maps were also calculated from the multiecho acquisitions. The noise standard deviation in the reconstructed phase images was evaluated for six manually segmented regions of interest (frontal white matter, posterior white matter, globus pallidus, putamen, caudate nucleus and lateral ventricle). The use of the multiecho sequence for susceptibility-weighted phase imaging led to a reduction of the noise standard deviation for all subjects and all regions of interest investigated in comparison to the reference single-echo acquisition. On average, the noise reduction ranged from 18.4% for the globus pallidus to 47.9% for the lateral ventricle. In addition, the amount of noise reduction was found to be strongly inversely correlated to the estimated R2 value (R=-0.92). In conclusion, the use of a multiecho sequence is an effective way to decrease the noise contribution in susceptibility-weighted phase images, while preserving both contrast and acquisition time. The proposed approach additionally permits the calculation of R2 maps. Copyright © 2012 Elsevier Inc. All rights reserved.
Behavior of quasinormal modes and high dimension RN-AdS black hole phase transition
Energy Technology Data Exchange (ETDEWEB)
Chabab, M.; Iraoui, S.; Masmar, K. [Cadi Ayyad University, High Energy Physics and Astrophysics Laboratory, Faculty of Science Semlalia, Marrakesh (Morocco); El Moumni, H. [Cadi Ayyad University, High Energy Physics and Astrophysics Laboratory, Faculty of Science Semlalia, Marrakesh (Morocco); Ibn Zohr University, LMTI, Physics Department, Faculty of Sciences, Agadir (Morocco)
2016-12-15
In this work we use the quasinormal frequencies of a massless scalar perturbation to probe the phase transition of the high dimension charged AdS black hole. The signature of the critical behavior of this black hole solution is detected in the isobaric as well as in isothermal process. This paper is a natural generalization of Liu et al. (JHEP 1409:179, 2014) to higher dimensional spacetime. More precisely our study shows a clear signal for any dimension d in the isobaric process. As to the isothermal case, we find that this signature can be affected by other parameters like the pressure and the horizon radius. We conclude that the quasinormal modes can be an efficient tool to investigate the first-order phase transition, but fail to disclose the signature of the second-order phase transition. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Soliman, A; Safigholi, H [Sunnybrook Research Institute, Toronto, ON (Canada); Sunnybrook Health Sciences Center, Toronto, ON (Canada); Nosrati, R [Sunnybrook Health Sciences Center, Toronto, ON (Canada); Ryerson University, Toronto, ON (Canada); Owrangi, A; Morton, G [Sunnybrook Health Sciences Center, Toronto, ON (Canada); University of Toronto, Toronto, ON (Canada); Song, W [Sunnybrook Research Institute, Toronto, ON (Canada); Sunnybrook Health Sciences Center, Toronto, ON (Canada); Ryerson University, Toronto, ON (Canada); University of Toronto, Toronto, ON (Canada)
2016-06-15
Purpose: To propose a new method that provides a positive contrast visualization of the prostate brachytherapy seeds using the phase information from MR images. Additionally, the feasibility of using the processed phase information to distinguish seeds from calcifications is explored. Methods: A gel phantom was constructed using 2% agar dissolved in 1 L of distilled water. Contrast agents were added to adjust the relaxation times. Four iodine-125 (Eckert & Ziegler SML86999) dummy seeds were placed at different orientations with respect to the main magnetic field (B0). Calcifications were obtained from a sheep femur cortical bone due to its close similarity to human bone tissue composition. Five samples of calcifications were shaped into different dimensions with lengths ranging between 1.2 – 6.1 mm.MR imaging was performed on a 3T Philips Achieva using an 8-channel head coil. Eight images were acquired at eight echo-times using a multi-gradient echo sequence. Spatial resolution was 0.7 × 0.7 × 2 mm, TR/TE/dTE = 20.0/2.3/2.3 ms and BW = 541 Hz/pixel. Complex images were acquired and fed into a two-step processing pipeline: the first includes phase unwrapping and background phase removal using Laplacian operator (Wei et al. 2013). The second step applies a specific phase mask on the resulting tissue phase from the first step to provide the desired positive contrast of the seeds and to, potentially, differentiate them from the calcifications. Results: The phase-processing was performed in less than 30 seconds. The proposed method has successfully resulted in a positive contrast of the brachytherapy seeds. Additionally, the final processed phase image showed difference between the appearance of seeds and calcifications. However, the shape of the seeds was slightly distorted compared to the original dimensions. Conclusion: It is feasible to provide a positive contrast of the seeds from MR images using Laplacian operator-based phase processing.
International Nuclear Information System (INIS)
Radhakrishnan, B.; Gorti, S.B.; Clarno, K.; Tonks, M.R.
2015-01-01
In this work, the phase-field method and its application to microstructure evolution in reactor fuel and clad are discussed. The examples highlight the capability of the phase-field method to capture evolution processes that are influenced by both thermal and elastic stress fields that are caused by microstructural changes in the solid-state. The challenges that need to be overcome before the technique can become predictive and material-specific are discussed. (authors)
Directory of Open Access Journals (Sweden)
J.L. Flanagan
2013-08-01
Full Text Available A vocoder technique is described in which speech signals are represented by their short-time phase and amplitude spectra. A complete transmission system utilizing this approach is simulated on a digital computer. The encoding method leads to an economy in transmission bandwidth and to a means for time compression and expansion of speech signals.
Directory of Open Access Journals (Sweden)
Yuncheng Bu
2018-03-01
Full Text Available The multi-baseline synthetic aperture radar (SAR tomography (TomoSAR system is employed in such applications as disaster remote sensing, urban 3-D reconstruction, and forest carbon storage estimation. This is because of its 3-D imaging capability in a single-pass platform. However, a high 3-D resolution of TomoSAR is based on the premise that the channel imbalance and antenna phase center (APC position are precisely known. If this is not the case, the 3-D resolution performance will be seriously degraded. In this paper, a unified algorithm for channel imbalance and APC position calibration of a single-pass multi-baseline TomoSAR system is proposed. Based on the maximum likelihood method, as well as the least squares and the damped Newton method, we can calibrate the channel imbalance and APC position. The algorithm is suitable for near-field conditions, and no phase unwrapping operation is required. The effectiveness of the proposed algorithm has been verified by simulation and experimental results.
Convex unwraps its first grown-up supercomputer
Energy Technology Data Exchange (ETDEWEB)
Manuel, T.
1988-03-03
Convex Computer Corp.'s new supercomputer family is even more of an industry blockbuster than its first system. At a tenfold jump in performance, it's far from just an incremental upgrade over its first minisupercomputer, the C-1. The heart of the new family, the new C-2 processor, churning at 50 million floating-point operations/s, spawns a group of systems whose performance could pass for some fancy supercomputers-namely those of the Cray Research Inc. family. When added to the C-1, Convex's five new supercomputers create the C series, a six-member product group offering a performance range from 20 to 200 Mflops. They mark an important transition for Convex from a one-product high-tech startup to a multinational company with a wide-ranging product line. It's a tough transition but the Richardson, Texas, company seems to be doing it. The extended product line propels Convex into the upper end of the minisupercomputer class and nudges it into the low end of the big supercomputers. It positions Convex in an uncrowded segment of the market in the $500,000 to $1 million range offering 50 to 200 Mflops of performance. The company is making this move because the minisuper area, which it pioneered, quickly became crowded with new vendors, causing prices and gross margins to drop drastically.
Sex and Candy: Unwrapping How We Define Sexuality
Ott, Kate
2016-01-01
When seeking a more nuanced understanding of sexuality, participants can benefit from hands-on activities that provide experience with the limitation of descriptors and social shaping of definitions. In many sexuality education contexts, participants enter the learning environment with a narrow definition of sexuality. The following game provides…
Unwrapping ADMM: Efficient Distributed Computing via Transpose Reduction
2016-05-11
applications of the Split Bregman method: Segmen- tation and surface reconstruction. J. Sci. Comput., 45:272– 293, October 2010. [17] Stephen Boyd and...Garcia, Gretchen Greene, Fabrizia Guglielmetti, Christopher Hanley, George Hawkins , et al. The second-generation guide star cata- log: description
Iterative-Transform Phase Retrieval Using Adaptive Diversity
Dean, Bruce H.
2007-01-01
A phase-diverse iterative-transform phase-retrieval algorithm enables high spatial-frequency, high-dynamic-range, image-based wavefront sensing. [The terms phase-diverse, phase retrieval, image-based, and wavefront sensing are defined in the first of the two immediately preceding articles, Broadband Phase Retrieval for Image-Based Wavefront Sensing (GSC-14899-1).] As described below, no prior phase-retrieval algorithm has offered both high dynamic range and the capability to recover high spatial-frequency components. Each of the previously developed image-based phase-retrieval techniques can be classified into one of two categories: iterative transform or parametric. Among the modifications of the original iterative-transform approach has been the introduction of a defocus diversity function (also defined in the cited companion article). Modifications of the original parametric approach have included minimizing alternative objective functions as well as implementing a variety of nonlinear optimization methods. The iterative-transform approach offers the advantage of ability to recover low, middle, and high spatial frequencies, but has disadvantage of having a limited dynamic range to one wavelength or less. In contrast, parametric phase retrieval offers the advantage of high dynamic range, but is poorly suited for recovering higher spatial frequency aberrations. The present phase-diverse iterative transform phase-retrieval algorithm offers both the high-spatial-frequency capability of the iterative-transform approach and the high dynamic range of parametric phase-recovery techniques. In implementation, this is a focus-diverse iterative-transform phaseretrieval algorithm that incorporates an adaptive diversity function, which makes it possible to avoid phase unwrapping while preserving high-spatial-frequency recovery. The algorithm includes an inner and an outer loop (see figure). An initial estimate of phase is used to start the algorithm on the inner loop, wherein
Moment-angle manifolds, intersection of quadrics and higher dimensional contact manifolds
Barreto, Yadira; Verjovsky, Alberto
2013-01-01
We construct new examples of contact manifolds in arbitrarily large dimensions. These manifolds which we call quasi moment-angle manifolds, are closely related to the classical moment-angle manifolds.
Scalar QNMs for higher dimensional black holes surrounded by quintessence in Rastall gravity
Energy Technology Data Exchange (ETDEWEB)
Graca, J.P.M.; Lobo, Iarley P. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil)
2018-02-15
The spacetime solution for a black hole, surrounded by an exotic matter field, in Rastall gravity, is calculated in an arbitrary d-dimensional spacetime. After this, we calculate the scalar quasinormal modes of such solution, and study the shift on the modes caused by the modification of the theory of gravity, i.e., by the introduction of a new term due to Rastall. We conclude that the shift strongly depends on the kind of exotic field one is studying, but for a low density matter that supposedly pervades the universe, it is unlikely that Rastall gravity will cause an instability for the probe field. (orig.)
Riccion from higher-dimensional space-time with D-dimensional ...
Indian Academy of Sciences (India)
suggest that space-time above 3 05¢1016 GeV should be fractal. .... Here VD is the volume of SD, g´4·Dµ is the determinant of the metric tensor gMN (M ...... means that above 3.05x1016 GeV, SD is not a smooth surface whereas M4 is smooth.
International Nuclear Information System (INIS)
Wiliardy, Abednego; Gunara, Bobby Eka
2016-01-01
An n dimensional flat manifold N is embedded into an n +1 dimensional stationary manifold M. The metric of M is derived from a general form of stationary manifold. By taking several assumption, such as 1) the ambient manifold M to be maximally symmetric space and satisfying a pure gauge condition, and 2) the submanifold is taken to be flat, then we find the solution that satisfies Ricci scalar of N . Moreover, we determine whether the solution is compatible with the Ricci and Riemann tensor of manifold N depending on the dimension. (paper)
Higher-Dimensional Origin of Heavy Sneutrino Domination and Low-Scale Leptogenesis
Hebecker, A; Yanagida, T
2003-01-01
If the expectation value of the right-handed (rhd) sneutrino comes to dominate the universe, its decay naturally leads to successful leptogenesis, as well as significant dilution of dangerous inflationary relics, such as the gravitino. The resulting baryon asymmetry is independent of other cosmological initial conditions. This attractive variant of leptogenesis requires at least one of the rhd neutrinos to have small Yukawa coupling and to have mass ~ 10^6 GeV, much smaller than the grand unified (GUT) scale. We show that these features naturally arise in the context of independently motivated and successful 5d orbifold GUTs with inverse-GUT-scale-sized extra dimensions. Rhd neutrinos are realized as bulk fields N_i with 5d bulk masses, while Yukawa couplings and lepton-number-violating masses for the N_i are localized at the SM boundary. The exponential suppression of the would-be N_i zero-modes leads to the desired small 4d Yukawa couplings and small masses for the rhd neutrino states. The see-saw predictio...
Late-time tails of wave propagation in higher dimensional spacetimes
International Nuclear Information System (INIS)
Cardoso, Vitor; Yoshida, Shijun; Dias, Oscar J.C.; Lemos, Jose P.S.
2003-01-01
We study the late-time tails appearing in the propagation of massless fields (scalar, electromagnetic, and gravitational) in the vicinities of a D-dimensional Schwarzschild black hole. We find that at late times the fields always exhibit a power-law falloff, but the power law is highly sensitive to the dimensionality of the spacetime. Accordingly, for odd D>3 we find that the field behaves as t -(2l+D-2) at late times, where l is the angular index determining the angular dependence of the field. This behavior is entirely due to D being odd; it does not depend on the presence of a black hole in the spacetime. Indeed this tail is already present in the flat space Green's function. On the other hand, for even D>4 the field decays as t -(2l+3D-8) , and this time there is no contribution from the flat background. This power law is entirely due to the presence of the black hole. The D=4 case is special and exhibits, as is well known, t -(2l+3) behavior. In the extra dimensional scenario for our Universe, our results are strictly correct if the extra dimensions are infinite, but also give a good description of the late-time behavior of any field if the large extra dimensions are large enough
Multiphysics Model of Palladium Hydride Isotope Exchange Accounting for Higher Dimensionality
Energy Technology Data Exchange (ETDEWEB)
Gharagozloo, Patricia E.; Eliassi, Mehdi; Bon, Bradley Luis
2015-03-01
This report summarizes computational model developm ent and simulations results for a series of isotope exchange dynamics experiments i ncluding long and thin isothermal beds similar to the Foltz and Melius beds and a lar ger non-isothermal experiment on the NENG7 test bed. The multiphysics 2D axi-symmetr ic model simulates the temperature and pressure dependent exchange reactio n kinetics, pressure and isotope dependent stoichiometry, heat generation from the r eaction, reacting gas flow through porous media, and non-uniformities in the bed perme ability. The new model is now able to replicate the curved reaction front and asy mmetry of the exit gas mass fractions over time. The improved understanding of the exchange process and its dependence on the non-uniform bed properties and te mperatures in these larger systems is critical to the future design of such sy stems.
Parallel-propagated frame along null geodesics in higher-dimensional black hole spacetimes
International Nuclear Information System (INIS)
Kubiznak, David; Frolov, Valeri P.; Connell, Patrick; Krtous, Pavel
2009-01-01
In [arXiv:0803.3259] the equations describing the parallel transport of orthonormal frames along timelike (spacelike) geodesics in a spacetime admitting a nondegenerate principal conformal Killing-Yano 2-form h were solved. The construction employed is based on studying the Darboux subspaces of the 2-form F obtained as a projection of h along the geodesic trajectory. In this paper we demonstrate that, although slightly modified, a similar construction is possible also in the case of null geodesics. In particular, we explicitly construct the parallel-transported frames along null geodesics in D=4, 5, 6 Kerr-NUT-(A)dS spacetimes. We further discuss the parallel transport along principal null directions in these spacetimes. Such directions coincide with the eigenvectors of the principal conformal Killing-Yano tensor. Finally, we show how to obtain a parallel-transported frame along null geodesics in the background of the 4D Plebanski-Demianski metric which admits only a conformal generalization of the Killing-Yano tensor.
Dynamics of higher-dimensional FRW cosmology in Rp exp(λR ...
Indian Academy of Sciences (India)
2017-01-04
Jan 4, 2017 ... In these theories, the Hilbert–Einstein action of general relativity (GR) is generalized by replacing the Ricci ... explain the inflationary expansion of the Universe. On the other ... dimensions will in general be different from that.
Fourier two-level analysis for higher dimensional discontinuous Galerkin discretisation
P.W. Hemker (Piet); M.H. van Raalte (Marc)
2002-01-01
textabstractIn this paper we study the convergence of a multigrid method for the solution of a two-dimensional linear second order elliptic equation, discretized by discontinuous Galerkin (DG) methods. For the Baumann-Oden and for the symmetric DG method, we give a detailed analysis of the
Surface Casimir densities and induced cosmological constant in higher dimensional braneworlds
International Nuclear Information System (INIS)
Saharian, Aram A.
2006-01-01
We investigate the vacuum expectation value of the surface energy-momentum tensor for a massive scalar field with general curvature coupling parameter obeying the Robin boundary conditions on two codimension one parallel branes in a (D+1)-dimensional background spacetime AdS D 1 +1 xΣ with a warped internal space Σ. These vacuum densities correspond to a gravitational source of the cosmological constant type for both subspaces of the branes. Using the generalized zeta function technique in combination with contour integral representations, the surface energies on the branes are presented in the form of the sum of single-brane and second-brane-induced parts. For the geometry of a single brane both regions, on the left and on the right of the brane, are considered. At the physical point the corresponding zeta functions contain pole and finite contributions. For an infinitely thin brane taking these regions together, in odd spatial dimensions the pole parts cancel and the total zeta function is finite. The renormalization procedure for the surface energies and the structure of the corresponding counterterms are discussed. The parts in the surface densities generated by the presence of the second brane are finite for all nonzero values of the interbrane separation and are investigated in various asymptotic regions of the parameters. In particular, it is shown that for large distances between the branes the induced surface densities give rise to an exponentially suppressed cosmological constant on the brane. The total energy of the vacuum including the bulk and boundary contributions is evaluated by the zeta function technique and the energy balance between separate parts is discussed
A higher-dimensional Bianchi type-I inflationary Universe in general ...
Indian Academy of Sciences (India)
Inflation, the stage of accelerated expansion of the Universe, first proposed ... ary model in the context of grand unified theory (GUT), which has been ... The role of self-interacting scalar fields in inflationary cosmology in four-dimensional.
Higher dimensional models of cross-coupled oscillators and application to design
Elwakil, Ahmed S.; Salama, Khaled N.
2010-01-01
We present four-dimensional and five-dimensional models for classical cross-coupled LC oscillators. Using these models, sinusoidal oscillation condition, frequency and amplitude can be found. Further, undesired behaviors such as relaxation-mode oscillations and latchup can be explained and detected. A simple graphical design procedure is also described. © 2010 World Scientific Publishing Company.
Exact solutions of Einstein and Einstein-Maxwell equations in higher-dimensional spacetime
International Nuclear Information System (INIS)
Xu Dianyan; Beijing Univ., BJ
1988-01-01
The D-dimensional Schwarzschild-de Sitter metric and Reissner-Nordstrom-de-Sitter metric are derived directly by solving the Einstein and Einstein-Maxwell equations. The D-dimensional Kerr metric is rederived by using the complex coordinate transformation method and the D-dimensional Kerr-de Sitter metric is also given. The conjecture about the D-dimensional metric of a rotating charged mass is given at the end of this paper. (author)
Higher Dimensional Kerr-Schild Spacetimes with (A)dS Background
Czech Academy of Sciences Publication Activity Database
Málek, T.; Pravda, Vojtěch
2011-01-01
Roč. 314, - (2011), 012111 ISSN 1742-6588. [Spanish Relativity Meeting (ERE 2010). Granada, 06.09.2010-10.09.2010] R&D Projects: GA ČR GAP203/10/0749 Institutional research plan: CEZ:AV0Z10190503 Keywords : Kerr-Schild metrics * Einstein equations Subject RIV: BA - General Mathematics http://iopscience.iop.org/1742-6596/314/1/012111
Higher Dimensional Charged Black Hole Solutions in f(R Gravitational Theories
Directory of Open Access Journals (Sweden)
G. G. L. Nashed
2018-01-01
Full Text Available We present, without any assumption, a class of electric and magnetic flat horizon D-dimension solutions for a specific class of f(R=R+αR2, all of which behave asymptotically as Anti-de-Sitter spacetime. The most interesting property of these solutions is that the higher dimensions black holes, D>4, always have constant electric and magnetic charges in contrast to what is known in the literature. For D=4, we show that the magnetic field participates in the metric on equal foot as the electric field participates. Another interesting result is the fact that the Cauchy horizon is not identical with the event horizon. We use Komar formula to calculate the conserved quantities. We study the singularities and calculate the Hawking temperature and entropy and show that the first law of thermodynamics is always satisfied.
Maximal locality and predictive power in higher-dimensional, compactified field theories
International Nuclear Information System (INIS)
Kubo, Jisuke; Nunami, Masanori
2004-01-01
To realize maximal locality in a trivial field theory, we maximize the ultraviolet cutoff of the theory by fine tuning the infrared values of the parameters. This optimization procedure is applied to the scalar theory in D + 1 dimensional (D ≥ 4) with one extra dimension compactified on a circle of radius R. The optimized, infrared values of the parameters are then compared with the corresponding ones of the uncompactified theory in D dimensions, which is assumed to be the low-energy effective theory. We find that these values approximately agree with each other as long as R -1 > approx sM is satisfied, where s ≅ 10, 50, 50, 100 for D = 4,5,6,7, and M is a typical scale of the D-dimensional theory. This result supports the previously made claim that the maximization of the ultraviolet cutoff in a nonrenormalizable field theory can give the theory more predictive power. (author)
On higher-dimensional loop algebras, pseudodifferential operators and Fock space realizations
International Nuclear Information System (INIS)
Westerberg, A.
1997-01-01
We discuss a previously discovered extension of the infinite-dimensional Lie algebra map(M,g) which generalizes the Kac-Moody algebras in 1+1 dimensions and the Mickelsson-Faddeev algebras in 3+1 dimensions to manifolds M of general dimensions. Furthermore, we review the method of regularizing current algebras in higher dimensions using pseudodifferential operator (PSDO) symbol calculus. In particular, we discuss the issue of Lie algebra cohomology of PSDOs and its relation to the Schwinger terms arising in the quantization process. Finally, we apply this regularization method to the algebra with partial success, and discuss the remaining obstacles to the construction of a Fock space representation. (orig.)
Faster exact algorithms for computing Steiner trees in higher dimensional Euclidean spaces
DEFF Research Database (Denmark)
Fonseca, Rasmus; Brazil, Marcus; Winter, Pawel
The Euclidean Steiner tree problem asks for a network of minimum total length interconnecting a finite set of points in d-dimensional space. For d ≥ 3, only one practical algorithmic approach exists for this problem --- proposed by Smith in 1992. A number of refinements of Smith's algorithm have...
Towards realistic models from Higher-Dimensional theories with Fuzzy extra dimensions
Gavriil, D.; Zoupanos, G.
2014-01-01
We briefly review the Coset Space Dimensional Reduction (CSDR) programme and the best model constructed so far and then we present some details of the corresponding programme in the case that the extra dimensions are considered to be fuzzy. In particular, we present a four-dimensional $\\mathcal{N} = 4$ Super Yang Mills Theory, orbifolded by $\\mathbb{Z}_3$, which mimics the behaviour of a dimensionally reduced $\\mathcal{N} = 1$, 10-dimensional gauge theory over a set of fuzzy spheres at intermediate high scales and leads to the trinification GUT $SU(3)^3$ at slightly lower, which in turn can be spontaneously broken to the MSSM in low scales.
The effective action for edge states in higher-dimensional quantum Hall systems
International Nuclear Information System (INIS)
Karabali, Dimitra; Nair, V.P.
2004-01-01
We show that the effective action for the edge excitations of a quantum Hall droplet of fermions in higher dimensions is generically given by a chiral bosonic action. We explicitly analyze the quantum Hall effect on complex projective spaces CP k , with a U(1) background magnetic field. The edge excitations are described by Abelian bosonic fields on S 2k-1 with only one spatial direction along the boundary of the droplet relevant for the dynamics. Our analysis also leads to an action for edge excitations for the case of the Zhang-Hu four-dimensional quantum Hall effect defined on S 4 with an SU(2) background magnetic field, using the fact that CP 3 is an S 2 -bundle over S 4
Higher dimensional models of cross-coupled oscillators and application to design
Elwakil, Ahmed S.
2010-06-01
We present four-dimensional and five-dimensional models for classical cross-coupled LC oscillators. Using these models, sinusoidal oscillation condition, frequency and amplitude can be found. Further, undesired behaviors such as relaxation-mode oscillations and latchup can be explained and detected. A simple graphical design procedure is also described. © 2010 World Scientific Publishing Company.
Approaches to analysis of data that concentrate near higher-dimensional manifolds
International Nuclear Information System (INIS)
Friedman, J.H.; Tukey, J.W.; Tukey, P.A.
1979-01-01
The need to explore structure in high-dimensional clouds of data points that may concentrate near (possibly nonlinear) manifolds of lower dimension led to the current development of three new approaches. The first is a computer-graphic system (PRIM'79) that facilitates interactive viewing and manipulation of an ensemble of points. The other two are automatic procedures for separating a cloud into more manageable pieces. One of these (BIDEC) performs successive partitioning of the cloud by use of hyperplanes; the other (Cake Maker) explores expanding sequences of neighborhoods. Both procedures provide facilities for examining the resulting pieces and the relationships among them
The Fuzzy analogy of chiral diffeomorphisms in higher dimensional quantum field theories
International Nuclear Information System (INIS)
Fassarella, Lucio; Schroer, Bert
2001-06-01
Our observation that the chiral diffeomorphisms allow an interpretation as modular groups of local operator algebras in the sense of Tomita and takesaki allows us to conclude that the higher deimensional generalizations are certain infinite dimensional groups which act in a 'fuzzy' way on the operator algebras of local quantum physics. These actions do not require any spacetime noncommutativity and are in complete harmony with causality and localization principles. The use of an appropriately defined isomorphism reprocesses these fuzzy actions into partially geometric actions on the holographic image and in this way tightens the relation with chiral structures and makes recent attempts to explain the required universal structure of a would be quantum Bekenstein law in terms of Virasoro algebra structures more palatable. (author)
Static and radiating p-form black holes in the higher dimensional Robinson-Trautman class
Czech Academy of Sciences Publication Activity Database
Ortaggio, Marcello; Podolský, J.; Žofka, M.
2015-01-01
Roč. 2015, č. 2 (2015), 045 ISSN 1029-8479 R&D Projects: GA ČR GB14-37086G Institutional support: RVO:67985840 Keywords : Einstein-Maxwell spacetimes * classical theories of gravity * black holes Subject RIV: BA - General Mathematics Impact factor: 6.023, year: 2015 http://link.springer.com/article/10.1007/JHEP02%282015%29045
First law of black ring thermodynamics in higher dimensional Chern-Simons gravity
International Nuclear Information System (INIS)
Rogatko, Marek
2007-01-01
The physical process version and the equilibrium state version of the first law of black ring thermodynamics in n-dimensional Einstein gravity with Chern-Simons term were derived. This theory constitutes the simplest generalization of the five-dimensional one admitting a stationary black ring solution. The equilibrium state version of the first law of black ring mechanics was achieved by choosing any cross section of the event horizon to the future of the bifurcation surface
Multi-phase flow monitoring with electrical impedance tomography using level set based method
International Nuclear Information System (INIS)
Liu, Dong; Khambampati, Anil Kumar; Kim, Sin; Kim, Kyung Youn
2015-01-01
Highlights: • LSM has been used for shape reconstruction to monitor multi-phase flow using EIT. • Multi-phase level set model for conductivity is represented by two level set functions. • LSM handles topological merging and breaking naturally during evolution process. • To reduce the computational time, a narrowband technique was applied. • Use of narrowband and optimization approach results in efficient and fast method. - Abstract: In this paper, a level set-based reconstruction scheme is applied to multi-phase flow monitoring using electrical impedance tomography (EIT). The proposed scheme involves applying a narrowband level set method to solve the inverse problem of finding the interface between the regions having different conductivity values. The multi-phase level set model for the conductivity distribution inside the domain is represented by two level set functions. The key principle of the level set-based method is to implicitly represent the shape of interface as the zero level set of higher dimensional function and then solve a set of partial differential equations. The level set-based scheme handles topological merging and breaking naturally during the evolution process. It also offers several advantages compared to traditional pixel-based approach. Level set-based method for multi-phase flow is tested with numerical and experimental data. It is found that level set-based method has better reconstruction performance when compared to pixel-based method
Phase contrast image synthesis
DEFF Research Database (Denmark)
Glückstad, J.
1996-01-01
A new method is presented for synthesizing arbitrary intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zernike phase contrast method into the domain of full range [0; 2 pi] phase modulation. By controlling the average value of the input phase funct...... function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished. The method presented is also directly applicable in dark field image synthesis....
Brignole, Esteban Alberto
2013-01-01
Traditionally, the teaching of phase equilibria emphasizes the relationships between the thermodynamic variables of each phase in equilibrium rather than its engineering applications. This book changes the focus from the use of thermodynamics relationships to compute phase equilibria to the design and control of the phase conditions that a process needs. Phase Equilibrium Engineering presents a systematic study and application of phase equilibrium tools to the development of chemical processes. The thermodynamic modeling of mixtures for process development, synthesis, simulation, design and
International Nuclear Information System (INIS)
Sikka, S.K.; Vohra, Y.K.; Chidambaram, R.
1982-01-01
The subject is reviewed under the headings: introduction; occurrence and some systematics of omega phase; crystallography; physical properties; kinetics of formation, synthesis and metastability of omega phase; electronic structure of omega phase; electronic basis for omega phase stability; omega phase formation under combined thermal and pressure treatment in alloys; transformation mechanisms and models for diffuse omega phase; conclusion. The following elements of nuclear interest (or their alloys) are included: Zr, Hf, Nb, V, Mo. (U.K.)
Fourier phasing with phase-uncertain mask
International Nuclear Information System (INIS)
Fannjiang, Albert; Liao, Wenjing
2013-01-01
Fourier phasing is the problem of retrieving Fourier phase information from Fourier intensity data. The standard Fourier phase retrieval (without a mask) is known to have many solutions which cause the standard phasing algorithms to stagnate and produce wrong or inaccurate solutions. In this paper Fourier phase retrieval is carried out with the introduction of a randomly fabricated mask in measurement and reconstruction. Highly probable uniqueness of solution, up to a global phase, was previously proved with exact knowledge of the mask. Here the uniqueness result is extended to the case where only rough information about the mask’s phases is assumed. The exponential probability bound for uniqueness is given in terms of the uncertainty-to-diversity ratio of the unknown mask. New phasing algorithms alternating between the object update and the mask update are systematically tested and demonstrated to have the capability of recovering both the object and the mask (within the object support) simultaneously, consistent with the uniqueness result. Phasing with a phase-uncertain mask is shown to be robust with respect to the correlation in the mask as well as the Gaussian and Poisson noises. (paper)
CrowdPhase: crowdsourcing the phase problem
Energy Technology Data Exchange (ETDEWEB)
Jorda, Julien; Sawaya, Michael R. [Institute for Genomics and Proteomics, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); Yeates, Todd O., E-mail: yeates@mbi.ucla.edu [Institute for Genomics and Proteomics, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); Molecular Biology Institute, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); University of California, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States)
2014-06-01
The idea of attacking the phase problem by crowdsourcing is introduced. Using an interactive, multi-player, web-based system, participants work simultaneously to select phase sets that correspond to better electron-density maps in order to solve low-resolution phasing problems. The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as ‘crowdsourcing’. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of ‘individuals’, each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it
CrowdPhase: crowdsourcing the phase problem
International Nuclear Information System (INIS)
Jorda, Julien; Sawaya, Michael R.; Yeates, Todd O.
2014-01-01
The idea of attacking the phase problem by crowdsourcing is introduced. Using an interactive, multi-player, web-based system, participants work simultaneously to select phase sets that correspond to better electron-density maps in order to solve low-resolution phasing problems. The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as ‘crowdsourcing’. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of ‘individuals’, each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it
DEFF Research Database (Denmark)
Glückstad, Jesper; Palima, Darwin
Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast...
Poirier, Bill; Salam, A
2004-07-22
In a previous paper [J. Theo. Comput. Chem. 2, 65 (2003)], one of the authors (B.P.) presented a method for solving the multidimensional Schrodinger equation, using modified Wilson-Daubechies wavelets, and a simple phase space truncation scheme. Unprecedented numerical efficiency was achieved, enabling a ten-dimensional calculation of nearly 600 eigenvalues to be performed using direct matrix diagonalization techniques. In a second paper [J. Chem. Phys. 121, 1690 (2004)], and in this paper, we extend and elaborate upon the previous work in several important ways. The second paper focuses on construction and optimization of the wavelength functions, from theoretical and numerical viewpoints, and also examines their localization. This paper deals with their use in representations and eigenproblem calculations, which are extended to 15-dimensional systems. Even higher dimensionalities are possible using more sophisticated linear algebra techniques. This approach is ideally suited to rovibrational spectroscopy applications, but can be used in any context where differential equations are involved.
Directory of Open Access Journals (Sweden)
Meng Cheng
2016-12-01
Full Text Available The Lieb-Schultz-Mattis theorem and its higher-dimensional generalizations by Oshikawa and Hastings require that translationally invariant 2D spin systems with a half-integer spin per unit cell must either have a continuum of low energy excitations, spontaneously break some symmetries, or exhibit topological order with anyonic excitations. We establish a connection between these constraints and a remarkably similar set of constraints at the surface of a 3D interacting topological insulator. This, combined with recent work on symmetry-enriched topological phases with on-site unitary symmetries, enables us to develop a framework for understanding the structure of symmetry-enriched topological phases with both translational and on-site unitary symmetries, including the effective theory of symmetry defects. This framework places stringent constraints on the possible types of symmetry fractionalization that can occur in 2D systems whose unit cell contains fractional spin, fractional charge, or a projective representation of the symmetry group. As a concrete application, we determine when a topological phase must possess a “spinon” excitation, even in cases when spin rotational invariance is broken down to a discrete subgroup by the crystal structure. We also describe the phenomena of “anyonic spin-orbit coupling,” which may arise from the interplay of translational and on-site symmetries. These include the possibility of on-site symmetry defect branch lines carrying topological charge per unit length and lattice dislocations inducing degeneracies protected by on-site symmetry.
High temperature phase equilibria and phase diagrams
Kuo, Chu-Kun; Yan, Dong-Sheng
2013-01-01
High temperature phase equilibria studies play an increasingly important role in materials science and engineering. It is especially significant in the research into the properties of the material and the ways in which they can be improved. This is achieved by observing equilibrium and by examining the phase relationships at high temperature. The study of high temperature phase diagrams of nonmetallic systems began in the early 1900s when silica and mineral systems containing silica were focussed upon. Since then technical ceramics emerged and more emphasis has been placed on high temperature
Therapy Provider Phase Information
U.S. Department of Health & Human Services — The Therapy Provider Phase Information dataset is a tool for providers to search by their National Provider Identifier (NPI) number to determine their phase for...
Micropatch Antenna Phase Shifting
National Research Council Canada - National Science Library
Thursby, Michael
2000-01-01
.... We have been looking at the ability of embedded element to adjust the phase shift seen by the element with the goal of being able to remove the phase shifting devices from the antenna and replace...
Micropatch Antenna Phase Shifting
National Research Council Canada - National Science Library
Thursby, Michael
1999-01-01
.... We have been looking at the ability of embedded element to adjust the phase shift seen by the element wit the goal of being able to remove the phase shifting devices from the antenna and replace...
Digital quadrature phase detection
Smith, J.A.; Johnson, J.A.
1992-05-26
A system for detecting the phase of a frequency or phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2[pi] when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2[pi] when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention. 6 figs.
Bowers, Michael T
1979-01-01
Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation
Brookner, E.
1985-02-01
The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US military systems COBRA DANE and PAVE PAWS as examples.
Computation of Phase Equilibrium and Phase Envelopes
DEFF Research Database (Denmark)
Ritschel, Tobias Kasper Skovborg; Jørgensen, John Bagterp
formulate the involved equations in terms of the fugacity coefficients. We present expressions for the first-order derivatives. Such derivatives are necessary in computationally efficient gradient-based methods for solving the vapor-liquid equilibrium equations and for computing phase envelopes. Finally, we......In this technical report, we describe the computation of phase equilibrium and phase envelopes based on expressions for the fugacity coefficients. We derive those expressions from the residual Gibbs energy. We consider 1) ideal gases and liquids modeled with correlations from the DIPPR database...... and 2) nonideal gases and liquids modeled with cubic equations of state. Next, we derive the equilibrium conditions for an isothermal-isobaric (constant temperature, constant pressure) vapor-liquid equilibrium process (PT flash), and we present a method for the computation of phase envelopes. We...
International Nuclear Information System (INIS)
Sikka, S.K.; Vohra, Y.K.; Chidambaram, R.
1982-01-01
The subject is covered in sections, entitled: introduction; occurrence and some systematics of omega phase (omega phase in Ti, Zr and Hf under high pressures; omega phase in Group IV transition metal alloys; omega in other systems; omega embryos at high temperatures); crystallography (omega structure; relationship of ω-structure to bcc (β) and hcp (α) structures); physical properties; kinetics of formation, synthesis and metastability of omega phase (kinetics of α-ω transformation under high pressures; kinetics of β-ω transformation; synthesis and metastability studies); electronic structure of omega phase (electronic structure models; band structure calculations; theoretical results and experimental studies); electronic basis for omega phase stability (unified phase diagram; stability of omega phase); omega phase formation under combined thermal and pressure treatment in alloys (Ti-V alloys under pressure - a prototype case study; P-X phase diagrams for alloys; transformation mechanisms and models for diffuse omega phase (is omega structure a charge density distortion of the bcc phase; nature of incommensurate ω-structure and models for diffuse scattering); conclusion. (U.K.)
Zhao, Bo
Phase transitions are one of the most exciting physical phenomena ever discovered. The understanding of phase transitions has long been of interest. Recently eigenstate phase transitions have been discovered and studied; they are drastically different from traditional thermal phase transitions. In eigenstate phase transitions, a sharp change is exhibited in properties of the many-body eigenstates of the Hamiltonian of a quantum system, but not the thermal equilibrium properties of the same system. In this thesis, we study two different types of eigenstate phase transitions. The first is the eigenstate phase transition within the ferromagnetic phase of an infinite-range spin model. By studying the interplay of the eigenstate thermalization hypothesis and Ising symmetry breaking, we find two eigenstate phase transitions within the ferromagnetic phase: In the lowest-temperature phase the magnetization can macroscopically oscillate by quantum tunneling between up and down. The relaxation of the magnetization is always overdamped in the remainder of the ferromagnetic phase, which is further divided into phases where the system thermally activates itself over the barrier between the up and down states, and where it quantum tunnels. The second is the many-body localization phase transition. The eigenstates on one side of the transition obey the eigenstate thermalization hypothesis; the eigenstates on the other side are many-body localized, and thus thermal equilibrium need not be achieved for an initial state even after evolving for an arbitrary long time. We study this many-body localization phase transition in the strong disorder renormalization group framework. After setting up a set of coarse-graining rules for a general one dimensional chain, we get a simple "toy model'' and obtain an almost purely analytical solution to the infinite-randomness critical fixed point renormalization group equation. We also get an estimate of the correlation length critical exponent nu
DEFF Research Database (Denmark)
Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez
2017-01-01
Single-phase phase-locked loops (PLLs) are popular for the synchronization and control of single-phase gridconnected converters. They are also widely used for monitoring and diagnostic purposes in the power and energy areas. In recent years, a large number of single-phase PLLs with different stru......-PLLs). The members of each category are then described and their pros and cons are discussed. This work provides a deep insight into characteristics of different single-phase PLLs and, therefore, can be considered as a reference for researchers and engineers....
Phase correction and error estimation in InSAR time series analysis
Zhang, Y.; Fattahi, H.; Amelung, F.
2017-12-01
During the last decade several InSAR time series approaches have been developed in response to the non-idea acquisition strategy of SAR satellites, such as large spatial and temporal baseline with non-regular acquisitions. The small baseline tubes and regular acquisitions of new SAR satellites such as Sentinel-1 allows us to form fully connected networks of interferograms and simplifies the time series analysis into a weighted least square inversion of an over-determined system. Such robust inversion allows us to focus more on the understanding of different components in InSAR time-series and its uncertainties. We present an open-source python-based package for InSAR time series analysis, called PySAR (https://yunjunz.github.io/PySAR/), with unique functionalities for obtaining unbiased ground displacement time-series, geometrical and atmospheric correction of InSAR data and quantifying the InSAR uncertainty. Our implemented strategy contains several features including: 1) improved spatial coverage using coherence-based network of interferograms, 2) unwrapping error correction using phase closure or bridging, 3) tropospheric delay correction using weather models and empirical approaches, 4) DEM error correction, 5) optimal selection of reference date and automatic outlier detection, 6) InSAR uncertainty due to the residual tropospheric delay, decorrelation and residual DEM error, and 7) variance-covariance matrix of final products for geodetic inversion. We demonstrate the performance using SAR datasets acquired by Cosmo-Skymed and TerraSAR-X, Sentinel-1 and ALOS/ALOS-2, with application on the highly non-linear volcanic deformation in Japan and Ecuador (figure 1). Our result shows precursory deformation before the 2015 eruptions of Cotopaxi volcano, with a maximum uplift of 3.4 cm on the western flank (fig. 1b), with a standard deviation of 0.9 cm (fig. 1a), supporting the finding by Morales-Rivera et al. (2017, GRL); and a post-eruptive subsidence on the same
International Nuclear Information System (INIS)
Wide, L.
1977-01-01
Solid phase coupled antibodies were introduced to facilitate the separation of bound and free labelled ligand in the competitive inhibition radioimmunoassay. Originally, the solid matrix used was in the form of small particles and since then a number of different matrices have been used such as very fine powder particles, gels, paper and plastic discs, magnetic particles and the inside surface of plastic tubes. The coupling of antibodies may be that of a covalent chemical binding, a strong physical adsorbtion, or an immunological binding to a solid phase coupled antigen. New principles of radioimmunoassay such as the solid phase sandwich techniques and the immunoradiometric assay were developped from the use of solid phase coupled antigens and antibodies. The solid phase sandwich techniques are reagent excess methods with a very wide applicability. Several of the different variants of solid phase techniques are suitable for automation. Advantages and disadvantages of solid phase radioimmunoassays when compared with those using soluble reagents are discussed. (orig.) [de
Glückstad, Jesper
2009-01-01
Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than the restrictive assumptions of conventional Zernike phase contrast analysis and achieves an expanded range of validity beyond weak phase perturbations. The generalized analysis yields design criteria for tuning experimental parameters to achieve optimal performance in terms of accuracy, fidelity and light efficiency. Optimization can address practical issues, such as finding an optimal spatial filter for the chosen application, ...
International Nuclear Information System (INIS)
Sachdev, S.
1999-01-01
Phase transitions are normally associated with changes of temperature but a new type of transition - caused by quantum fluctuations near absolute zero - is possible, and can tell us more about the properties of a wide range of systems in condensed-matter physics. Nature abounds with phase transitions. The boiling and freezing of water are everyday examples of phase transitions, as are more exotic processes such as superconductivity and superfluidity. The universe itself is thought to have passed through several phase transitions as the high-temperature plasma formed by the big bang cooled to form the world as we know it today. Phase transitions are traditionally classified as first or second order. In first-order transitions the two phases co-exist at the transition temperature - e.g. ice and water at 0 deg., or water and steam at 100 deg. In second-order transitions the two phases do not co-exist. In the last decade, attention has focused on phase transitions that are qualitatively different from the examples noted above: these are quantum phase transitions and they occur only at the absolute zero of temperature. The transition takes place at the ''quantum critical'' value of some other parameter such as pressure, composition or magnetic field strength. A quantum phase transition takes place when co-operative ordering of the system disappears, but this loss of order is driven solely by the quantum fluctuations demanded by Heisenberg's uncertainty principle. The physical properties of these quantum fluctuations are quite distinct from those of the thermal fluctuations responsible for traditional, finite-temperature phase transitions. In particular, the quantum system is described by a complex-valued wavefunction, and the dynamics of its phase near the quantum critical point requires novel theories that have no analogue in the traditional framework of phase transitions. In this article the author describes the history of quantum phase transitions. (UK)
McGraw, John T [Placitas, NM; Zimmer, Peter C [Albuquerque, NM; Ackermann, Mark R [Albuquerque, NM
2012-01-24
Methods and apparatus for a structure function monitor provide for generation of parameters characterizing a refractive medium. In an embodiment, a structure function monitor acquires images of a pupil plane and an image plane and, from these images, retrieves the phase over an aperture, unwraps the retrieved phase, and analyzes the unwrapped retrieved phase. In an embodiment, analysis yields atmospheric parameters measured at spatial scales from zero to the diameter of a telescope used to collect light from a source.
Gravity waves from the non-renormalizable electroweak vacua phase transition
Energy Technology Data Exchange (ETDEWEB)
Greenwood, Eric [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics; Vaudrevange, Pascal M. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2010-11-15
It is currently believed that the Standard Model is an effective low energy theory which in principle may contain higher dimensional non-renormalizable operators. These operators may modify the standard model Higgs potential in many ways, one of which being the appearance of a second vacuum. For a wide range of parameters, this new vacuum becomes the true vacuum. It is then assumed that our universe is currently sitting in the false vacuum. Thus the usual second-order electroweak phase transition at early times will be followed by a second, first-order phase transition. In cosmology, a first-order phase transition is associated with the production of gravity waves. In this paper we present an analysis of the production of gravitational waves during such a second electroweak phase transition. We find that, for one certain range of parameters, the stochastic background of gravitational waves generated by bubble nucleation and collision have an amplitude which is estimated to be of order {omega}{sub GW}h{sup 2}{proportional_to}10{sup -11} at f=3 x 10{sup -4} Hz, which is within reach of the planned sensitivity of LISA. For another range of parameters, we find that the amplitude is estimated to be of order {omega}{sub GW}h{sup 2}{proportional_to} 0{sup -25} around f=10{sup 3} Hz, which is within reach of LIGO. Hence, it is possible to detect gravity waves from such a phase transition at two different detectors, with completely different amplitude and frequency ranges. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Chao, Alexander Wu; /SLAC
2012-03-01
As accelerator technology advances, the requirements on accelerator beam quality become increasingly demanding. Facing these new demands, the topic of phase space gymnastics is becoming a new focus of accelerator physics R&D. In a phase space gymnastics, the beam's phase space distribution is manipulated and precision tailored to meet the required beam qualities. On the other hand, all realization of such gymnastics will have to obey accelerator physics principles as well as technological limitations. Recent examples of phase space gymnastics include Emittance exchanges, Phase space exchanges, Emittance partitioning, Seeded FELs and Microbunched beams. The emittance related topics of this list are reviewed in this report. The accelerator physics basis, the optics design principles that provide these phase space manipulations, and the possible applications of these gymnastics, are discussed. This fascinating new field promises to be a powerful tool of the future.
Diffusionless phase transformations
International Nuclear Information System (INIS)
Vejman, K.M.
1987-01-01
Diffusionless phase transformations in metals and alloys in the process of which atomic displacements occur at the distances lower than interatomic ones and relative correspondence of neighbour atoms is preserved, are considered. Special attention is paid to the mechanism of martensitic transformations. Phenomenologic crystallographical theory of martensitic transformations are presented. Two types of martensitic transformations different from the energy viewpoint are pointed out - thermoelastic and non-thermoelastic ones - which are characterized by transformation hysteresis and ways of martensite - initial phase reverse transformation realization. Mechanical effect in the martensitic transformations have been analyzed. The problem of diffusionless formation of ω-phases and the effect of impurities and vacancies on the process are briefly discussed. The role of charge density waves in phase transformations of the second type (transition of initial phase into noncommensurate one) and of the first type (transition of noncommensurate phase into commensurate one) is considered
DEFF Research Database (Denmark)
1996-01-01
The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift phi is less than 1 radian. An improved method based on a simple imaging operation...... phasors attain predetermined values for predetermined spatial frequencies, and the phasor value of the specific resolution element of the spatial phase mask corresponds to a distinct intensity level of the image of the resolution element in the intensity pattern, and a spatial phase filter for phase...... shifting of a part of the electromagntic radiation, in combination with an imaging system for generation of the intensity pattern by interference in the image plane of the imaging system between the part of the electromagnetic raidation that has been phase shifted by the phase filter and the remaining part...
International Nuclear Information System (INIS)
Checon, A.
1983-01-01
Theoretical formulation of a straight edge diffraction shows a phase difference of π/2 between the incoming and diffracted waves. Experiments using two straight edges do not confirm the π/2 difference but suggest that the incoming wave is in phase with the wave diffracted into the shadowed region of the edge and out of phase by a factor of π with the wave diffracted into the illuminated region. (Author) [pt
Cosmological phase transitions
International Nuclear Information System (INIS)
Kolb, E.W.
1993-10-01
If modern ideas about the role of spontaneous symmetry breaking in fundamental physics are correct, then the Universe should have undergone a series of phase transitions early in its history. The study of cosmological phase transitions has become an important aspect of early-Universe cosmology. In this lecture I review some very recent work on three aspects of phase transitions: the electroweak transition, texture, and axions
Maker, Paul D.; Muller, Richard E.
1994-01-01
Complex, computer-generated phase holograms written in thin films of poly(methyl methacrylate) (PMMA) by process of electron-beam exposure followed by chemical development. Spatial variations of phase delay in holograms quasi-continuous, as distinquished from stepwise as in binary phase holograms made by integrated-circuit fabrication. Holograms more precise than binary holograms. Greater continuity and precision results in decreased scattering loss and increased imaging efficiency.
Thermodynamics of phase transitions
International Nuclear Information System (INIS)
Cofta, H.
1972-01-01
The phenomenology of the phase transitions has been considered. The definitions of thermodynamic functions and parameters, as well as those of the phase transitions, are given and some of the relations between those quantities are discussed. The phase transitions classification proposed by Ehrenfest has been described. The most important features of phase transitions are discussed using the selected physical examples including the critical behaviour of ferromagnetic materials at the Curie temperature and antiferromagnetic materials at the Neel temperature. Some aspects of the Ehrenfest's equations, that have been derived, for the interfacial lines and surfaces are considered as well as the role the notion of interfaces. (S.B.)
Retroreflective Phase Retardation Prisms.
1981-06-01
resonant cavity of a 1.064 Mm laser. This report shows that it is possible to coat the reflecting surfaces of a porro prism so that incident plane...with controlled phase retardation can be made by coating each reflecting surface of a porro prism with a single dielectric film. The amount of phase...of angle of incidence (n, < n2) S. Phase change on reflection as a function of angle of incidence (n" n ) [RL-0202-’R 6. Porro prism 7. Phase change
Green, David G; Abbass, Hussein A
2014-01-01
This book explains how dual phase evolution operates in all these settings and provides a detailed treatment of the subject. The authors discuss the theoretical foundations for the theory, how it relates to other phase transition phenomena and its advantages in evolutionary computation and complex adaptive systems. The book provides methods and techniques to use this concept for problem solving. Dual phase evolution concerns systems that evolve via repeated phase shifts in the connectivity of their elements. It occurs in vast range of settings, including natural systems (species evolution, landscape ecology, geomorphology), socio-economic systems (social networks) and in artificial systems (annealing, evolutionary computing).
Soustelle, Michel
2015-01-01
This book is part of a set of books which offers advanced students successive characterization tool phases, the study of all types of phase (liquid, gas and solid, pure or multi-component), process engineering, chemical and electrochemical equilibria, and the properties of surfaces and phases of small sizes. Macroscopic and microscopic models are in turn covered with a constant correlation between the two scales. Particular attention has been given to the rigor of mathematical developments. This second volume in the set is devoted to the study of liquid phases.
National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will investigate a new architecture for photovoltaic devices based on nanotechnology: photovoltaic wire. The...
International Nuclear Information System (INIS)
Lippert, Matthew
2009-01-01
We investigated the Sakai-Sugimoto model of large N QCD at nonzero temperature and baryon chemical potential and in the presence of background electric and magnetic fields. We studied the holographic representation of baryons and the deconfinement, chiral-symmetry breaking, and nuclear matter phase transitions. In a background electric field, chiral-symmetry breaking corresponds to an insulator-conductor transition. A magnetic field both catalyzes chiral-symmetry breaking and generates, in the confined phase, a pseudo-scalar gradient or, in the deconfined phase, an axial current. The resulting phase diagram is in qualitative agreement with studies of hot, dense QCD.
International Nuclear Information System (INIS)
Menk, Ralf Hendrik
2008-01-01
All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift φ directly (using interference phenomena), the gradient ∇ φ , or the Laplacian ∇ 2 φ. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1,000-10,000 in the energy
International Nuclear Information System (INIS)
Blanchard, R.J.
1995-01-01
This documents Phase 1 determinations on sampler induced bias for four sampler types used in tank characterization. Each sampler, grab sampler or bottle-on-a-string, auger sampler, sludge sampler and universal sampler, is briefly discussed and their physical limits noted. Phase 2 of this document will define additional testing and analysis to further define Sampler Bias
Shawl, Stephen J.
2010-01-01
This paper describes a lunar phases planisphere with which a user can answer questions about the rising and setting times of the Moon as well as questions about where the Moon will be at a given phase and time. The article contains figures that can be photocopied to make the planisphere. (Contains 2 figures.)
Fisher, Robert A
1983-01-01
This book appears at a time of intense activity in optical phase conjugation. We chose not to await the maturation of the field, but instead to provide this material in time to be useful in its development. We have tried very hard to elucidate and interrelate the various nonlinear phenomena which can be used for optical phase conjugation.
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-08-01
The Utility PhotoVoltaic Group (UPVG), supported by member dues and a grant from the US Department of Energy, has as its mission the acceleration of the use of cost-effective small-scale and emerging large-scale applications of photovoltaics for the benefit of electric utilities and their customers. Formed in October, 1992, with the support of the American Public Power Association, Edison Electric Institute, and the National Rural Electric Cooperative Association, the UPVG currently has 90 members from all sectors of the electric utility industry. The UPVG`s efforts as conceived were divided into four phases: Phase 0--program plan; Phase 1--organization and strategy development; Phase 2--creating market assurance; and Phase 3--higher volume purchases. The Phase 0 effort developed the program plan and was completed early in 1993. The Phase 1 goal was to develop the necessary background information and analysis to lead to a decision as to which strategies could be undertaken by utilities to promote greater understanding of PV markets and achieve increased volumes of PV purchases. This report provides the details of the UPVG`s Phase 2 efforts to initiate TEAM-UP, its multiyear, 50-MW hardware initiative.
Simulation of phase structures
International Nuclear Information System (INIS)
Lawson, J.
1995-01-01
This memo outlines a procedure developed by the author to extract information from phase measurements and produce a simulated phase structure for use in modeling optical systems, including characteristic optics for the Beamlet and NIF laser systems. The report includes an IDL program listing
International Nuclear Information System (INIS)
1995-08-01
The Utility PhotoVoltaic Group (UPVG), supported by member dues and a grant from the US Department of Energy, has as its mission the acceleration of the use of cost-effective small-scale and emerging large-scale applications of photovoltaics for the benefit of electric utilities and their customers. Formed in October, 1992, with the support of the American Public Power Association, Edison Electric Institute, and the National Rural Electric Cooperative Association, the UPVG currently has 90 members from all sectors of the electric utility industry. The UPVG's efforts as conceived were divided into four phases: Phase 0--program plan; Phase 1--organization and strategy development; Phase 2--creating market assurance; and Phase 3--higher volume purchases. The Phase 0 effort developed the program plan and was completed early in 1993. The Phase 1 goal was to develop the necessary background information and analysis to lead to a decision as to which strategies could be undertaken by utilities to promote greater understanding of PV markets and achieve increased volumes of PV purchases. This report provides the details of the UPVG's Phase 2 efforts to initiate TEAM-UP, its multiyear, 50-MW hardware initiative
Smooth Phase Interpolated Keying
Borah, Deva K.
2007-01-01
Smooth phase interpolated keying (SPIK) is an improved method of computing smooth phase-modulation waveforms for radio communication systems that convey digital information. SPIK is applicable to a variety of phase-shift-keying (PSK) modulation schemes, including quaternary PSK (QPSK), octonary PSK (8PSK), and 16PSK. In comparison with a related prior method, SPIK offers advantages of better performance and less complexity of implementation. In a PSK scheme, the underlying information waveform that one seeks to convey consists of discrete rectangular steps, but the spectral width of such a waveform is excessive for practical radio communication. Therefore, the problem is to smooth the step phase waveform in such a manner as to maintain power and bandwidth efficiency without incurring an unacceptably large error rate and without introducing undesired variations in the amplitude of the affected radio signal. Although the ideal constellation of PSK phasor points does not cause amplitude variations, filtering of the modulation waveform (in which, typically, a rectangular pulse is converted to a square-root raised cosine pulse) causes amplitude fluctuations. If a power-efficient nonlinear amplifier is used in the radio communication system, the fluctuating-amplitude signal can undergo significant spectral regrowth, thus compromising the bandwidth efficiency of the system. In the related prior method, one seeks to solve the problem in a procedure that comprises two major steps: phase-value generation and phase interpolation. SPIK follows the two-step approach of the related prior method, but the details of the steps are different. In the phase-value-generation step, the phase values of symbols in the PSK constellation are determined by a phase function that is said to be maximally smooth and that is chosen to minimize the spectral spread of the modulated signal. In this step, the constellation is divided into two groups by assigning, to information symbols, phase values
International Nuclear Information System (INIS)
Read, R.J.; Schierbeek, A.J.
1988-01-01
A phased translation function, which takes advantage of prior phase information to determine the position of an oriented mulecular replacement model, is examined. The function is the coefficient of correlation between the electron density computed with the prior phases and the electron density of the translated model, evaluated in reciprocal space as a Fourier transform. The correlation coefficient used in this work is closely related to an overlap function devised by Colman, Fehlhammer and Bartels. Tests with two protein structures, one of which was solved with the help of the phased translation function, show that little phase information is required to resolve the translation problem, and that the function is relatively insensitive to misorientation of the model. (orig.)
International Nuclear Information System (INIS)
Kehayias, John; Profumo, Stefano
2010-01-01
Upcoming gravitational wave (GW) detectors might detect a stochastic background of GWs potentially arising from many possible sources, including bubble collisions from a strongly first-order electroweak phase transition. We investigate whether it is possible to connect, via a semi-analytical approximation to the tunneling rate of scalar fields with quartic potentials, the GW signal through detonations with the parameters entering the potential that drives the electroweak phase transition. To this end, we consider a finite temperature effective potential similar in form to the Higgs potential in the Standard Model (SM). In the context of a semi-analytic approximation to the three dimensional Euclidean action, we derive a general approximate form for the tunneling temperature and the relevant GW parameters. We explore the GW signal across the parameter space describing the potential which drives the phase transition. We comment on the potential detectability of a GW signal with future experiments, and physical relevance of the associated potential parameters in the context of theories which have effective potentials similar in form to that of the SM. In particular we consider singlet, triplet, higher dimensional operators, and top-flavor extensions to the Higgs sector of the SM. We find that the addition of a temperature independent cubic term in the potential, arising from a gauge singlet for instance, can greatly enhance the GW power. The other parameters have milder, but potentially noticeable, effects
Energy Technology Data Exchange (ETDEWEB)
Schmidt, R.
2007-03-15
The present work is addressed to defects and boundaries in quantum field theory considering the application to AdS/CFT correspondence. We examine interactions of fermions with spins localised on these boundaries. Therefore, an algebra method is emphasised adding reflection and transmission terms to the canonical quantisation prescription. This method has already been applied to bosons in two space-time dimensions before. We show the possibilities of such reflection-transmission algebras in two, three, and four dimensions. We compare with models of solid state physics as well as with the conformal field theory approach to the Kondo effect. Furthermore, we discuss ansatzes of extensions to lattice structures. (orig.)
2013-12-01
depiction of “space” is simplified (for pedagogical purposes) as a 2-D plane with a point in that planar “space” defined by its location in Cartesian...93 define a value associated with the color of each plotted dot. For pedagogical purposes, the color scale in this example is discretized to only...trajectory design in this 146 investigation, a “zoom” in color is often accompanied by a filtering based on the same color scale limits, thus
Dorren, H.J.S.
1998-01-01
It is shown that the Korteweg–de Vries (KdV) equation can be transformed into an ordinary linear partial differential equation in the wave number domain. Explicit solutions of the KdV equation can be obtained by subsequently solving this linear differential equation and by applying a cascade of
Ryttov, Thomas A
2007-01-01
We present the conformal windows of SU(N) supersymmetric and nonsupersymmetric gauge theories with vector-like matter transforming according to higher irreducible representations of the gauge group. We determine the fraction of asymptotically free theories expected to develop an infrared fixed point and find that it does not depend on the specific choice of the representation. This result is exact in supersymmetric theories while it is an approximate one in the nonsupersymmetric case. The analysis allows us to size the unparticle world related to the existence of underlying gauge theories developing an infrared stable fixed point. We find that exactly 50 % of the asymptotically free theories can develop an infrared fixed point while for the nonsupersymmetric theories it is circa 25 %. When considering multiple representations, only for the nonsupersymmetric case, the conformal regions quickly dominate over the nonconformal ones. For four representations, 70 % of the asymptotically free space is filled by the ...
International Nuclear Information System (INIS)
Ryttov, Thomas A.; Sannino, Francesco
2007-01-01
We present the conformal windows of SU(N) supersymmetric and nonsupersymmetric gauge theories with vectorlike matter transforming according to higher irreducible representations of the gauge group. We determine the fraction of asymptotically free theories expected to develop an infrared fixed point and find that it does not depend on the specific choice of the representation. This result is exact in supersymmetric theories while it is an approximate one in the nonsupersymmetric case. The analysis allows us to size the unparticle world related to the existence of underlying gauge theories developing an infrared stable fixed point. We find that exactly 50% of the asymptotically free theories can develop an infrared fixed point while for the nonsupersymmetric theories it is circa 25%. When considering multiple representations, only for the nonsupersymmetric case, the conformal regions quickly dominate over the nonconformal ones. For four representations, 70% of the asymptotically free space is filled by the conformal region. According to our theoretical landscape survey the unparticle physics world occupies a sizable amount of the particle world, at least in theory space, and before mixing it (at the operator level) with the nonconformal one
International Nuclear Information System (INIS)
Nariai, Hidekazu; Ishihara, Hideki.
1983-01-01
Various geometrical properties of Nariai's less-familiar solution of the vacuum Einstein equations R sub( mu nu ) = lambda g sub( mu nu ) is f irst summarized in comparison with de Sitter's well-known solution. Next an extension of both solutions is performed in a six-dimensional space on the supposition that such an extension will in future become useful to elucidate more closely the creation of particles in an inflationary stage of the big-bang universe. For preparation, the behavior of a massive scalar field in the extended space-time is studied in a classical level. (author)
International Nuclear Information System (INIS)
Townsend, P.K.; Sierra, G.
1983-01-01
Chiral anomalies for gauge theories in any even dimension are computed and the results applied to supersymmetric theories in D=6, 8 and 10. For D=8 there is an anomalous chiral U(1) invariance, just as in D=4, except for certain special groups. For D=6 and D=10 there is no anomalous chiral U(1) symmetry, but the gauge current is anomalous except for certain ''anomaly-free'' groups. For D=6 the group is thereby constrained to be one of [SU(2), SU(3), exceptional], while for D=10 it is constrained to be one of [SU(n)n 8 ]. (orig.)
International Nuclear Information System (INIS)
Spinelly, J.; Mello, E.R. Bezerra de
2008-01-01
In this paper we investigate the vacuum polarization effects associated with quantum fermionic charged fields in a generalized (d+1)-dimensional cosmic string space-times considering the presence of a magnetic flux along the string. In order to develop this analysis we calculate a general expression for the respective Green function, valid for several different values of d, which is expressed in terms of a bispinor associated with the square of the Dirac operator. Adopting this result, we explicitly calculate the renormalized vacuum expectation values of the energy-momentum tensors, (T A B ) Ren. , associated with massless fields. Moreover, for specific values of the parameters which codify the cosmic string and the fractional part of the ratio of the magnetic flux by the quantum one, we were able to present in closed forms the bispinor and the respective Green function for massive fields.
Marcin, Martin; Abramovici, Alexander
2008-01-01
The software of a commercially available digital radio receiver has been modified to make the receiver function as a two-channel low-noise phase meter. This phase meter is a prototype in the continuing development of a phase meter for a system in which radiofrequency (RF) signals in the two channels would be outputs of a spaceborne heterodyne laser interferometer for detecting gravitational waves. The frequencies of the signals could include a common Doppler-shift component of as much as 15 MHz. The phase meter is required to measure the relative phases of the signals in the two channels at a sampling rate of 10 Hz at a root power spectral density measurements in laser metrology of moving bodies. To illustrate part of the principle of operation of the phase meter, the figure includes a simplified block diagram of a basic singlechannel digital receiver. The input RF signal is first fed to the input terminal of an analog-to-digital converter (ADC). To prevent aliasing errors in the ADC, the sampling rate must be at least twice the input signal frequency. The sampling rate of the ADC is governed by a sampling clock, which also drives a digital local oscillator (DLO), which is a direct digital frequency synthesizer. The DLO produces samples of sine and cosine signals at a programmed tuning frequency. The sine and cosine samples are mixed with (that is, multiplied by) the samples from the ADC, then low-pass filtered to obtain in-phase (I) and quadrature (Q) signal components. A digital signal processor (DSP) computes the ratio between the Q and I components, computes the phase of the RF signal (relative to that of the DLO signal) as the arctangent of this ratio, and then averages successive such phase values over a time interval specified by the user.
Phase transformation and diffusion
Kale, G B; Dey, G K
2008-01-01
Given that the basic purpose of all research in materials science and technology is to tailor the properties of materials to suit specific applications, phase transformations are the natural key to the fine-tuning of the structural, mechanical and corrosion properties. A basic understanding of the kinetics and mechanisms of phase transformation is therefore of vital importance. Apart from a few cases involving crystallographic martensitic transformations, all phase transformations are mediated by diffusion. Thus, proper control and understanding of the process of diffusion during nucleation, g
Gas Phase Nanoparticle Synthesis
Granqvist, Claes; Kish, Laszlo; Marlow, William
This book deals with gas-phase nanoparticle synthesis and is intended for researchers and research students in nanomaterials science and engineering, condensed matter physics and chemistry, and aerosol science. Gas-phase nanoparticle synthesis is instrumental to nanotechnology - a field in current focus that raises hopes for environmentally benign, resource-lean manufacturing. Nanoparticles can be produced by many physical, chemical, and even biological routes. Gas-phase synthesis is particularly interesting since one can achieve accurate manufacturing control and hence industrial viability.
International Nuclear Information System (INIS)
Petry, W.; Neuhaus, J.
1996-01-01
Many elements transform from a high temperature bcc phase to a more dense packed temperature phase. The great majority of these transitions are of 1st order, displacive and reconstructive. The lattice potentials which govern these martensitic transitions can be probed by inelastic neutron scattering, thereby answering fundamental questions like : Will the transition be announced by dynamical or static fluctuations? What are the trajectories for the displacements needed for the transformation? Does the vibrational entropy stabilize the high temperature phase? Are the unusual transport properties in these materials related to their ability to transform? (author) 17 figs., 1 tab., 46 refs
Energy Technology Data Exchange (ETDEWEB)
Petry, W; Neuhaus, J [Techn. Universitaet Muenchen, Physik Department E13, Munich (Germany)
1996-11-01
Many elements transform from a high temperature bcc phase to a more dense packed temperature phase. The great majority of these transitions are of 1st order, displacive and reconstructive. The lattice potentials which govern these martensitic transitions can be probed by inelastic neutron scattering, thereby answering fundamental questions like : Will the transition be announced by dynamical or static fluctuations? What are the trajectories for the displacements needed for the transformation? Does the vibrational entropy stabilize the high temperature phase? Are the unusual transport properties in these materials related to their ability to transform? (author) 17 figs., 1 tab., 46 refs.
Su, Wei-Hung; Kuo, Cho-Yo; Kao, Fu-Jen
2014-08-20
A fringe projection technique to trace the shape of a fast-moving object is proposed. A binary-encoded fringe pattern is illuminated by a strobe lamp and then projected onto the moving object at a sequence of time. Phases of the projected fringes obtained from the sequent measurements are extracted by the Fourier transform method. Unwrapping is then performed with reference to the binary-encoded fringe pattern. Even though the inspected object is colorful, fringe orders can be identified. A stream of profiles is therefore retrieved from the sequent unwrapped phases. This makes it possible to analyze physical properties of the dynamic objects. Advantages of the binary-encoded fringe pattern for phase unwrapping also include (1) reliable performance for colorful objects, spatially isolated objects, and surfaces with large depth discontinuities; (2) unwrapped errors only confined in a local area; and (3) low computation cost.
Katarina Anthony
2012-01-01
Building on the success of their feasibility phase, the CLIC test facility, CTF3, has just launched into a five-year project development phase. This will involve detailed performance optimisation studies, marking the project’s transition from pure research and development to prototyping and construction. CLIC accelerator modules under construction at CERN. “With the feasibility phase now complete, we have established that CLIC can be built,” says Roberto Corsini, CLIC Collaboration spokesperson. “Now we want to be sure that it can provide the luminosity and energy performance needed. We will be looking at the engineering, performance and cost of a real CLIC machine also seeing if we can reduce it.” CTF3’s second phase will focus on selected performance-related research areas for further investigation. The largest of these involves the construction and testing of several authentic CLIC accelerator modules that are currently being ...
Phase transitions modern applications
Gitterman, Moshe
2014-01-01
This book provides a comprehensive review of the theory of phase transitions and its modern applications, based on the five pillars of the modern theory of phase transitions i.e. the Ising model, mean field, scaling, renormalization group and universality. This expanded second edition includes, along with a description of vortices and high temperature superconductivity, a discussion of phase transitions in chemical reaction and moving systems. The book covers a close connection between phase transitions and small world phenomena as well as scale-free systems such as the stock market and the Internet. Readership: Scientists working in different fields of physics, chemistry, biology and economics as well as teaching material for undergraduate and graduate courses.
International Nuclear Information System (INIS)
Watson, R.E.; Ehrenreich, H.; Bennett, L.H.
1977-01-01
Various non-thermodynamic approaches to understanding and predicting phase diagrams are explored from the viewpoint of solid-state physics. The review is intended to indicate the scope of activity and some of the progress which has been made
Doland, G. D. (Inventor)
1978-01-01
Several new and useful improvements in steering and control of phased array antennas having a small number of elements, typically on the order of 5 to 17 elements are provided. Among the improvements are increasing the number of beam steering positions, reducing the possibility of phase transients in signals received or transmitted with the antennas, and increasing control and testing capacity with respect to the antennas.
Ahmad, Zahoor; Hanif, Muhammad
2013-01-01
The development of estimators of population parameters based on two-phase sampling schemes has seen a dramatic increase in the past decade. Various authors have developed estimators of population using either one or two auxiliary variables. The present volume is a comprehensive collection of estimators available in single and two phase sampling. The book covers estimators which utilize information on single, two and multiple auxiliary variables of both quantitative and qualitative nature. Th...
Phase Control in Nonlinear Systems
Zambrano, Samuel; Seoane, Jesús M.; Mariño, Inés P.; Sanjuán, Miguel A. F.; Meucci, Riccardo
The following sections are included: * Introduction * Phase Control of Chaos * Description of the model * Numerical exploration of phase control of chaos * Experimental evidence of phase control of chaos * Phase Control of Intermittency in Dynamical Systems * Crisis-induced intermittency and its control * Experimental setup and implementation of the phase control scheme * Phase control of the laser in the pre-crisis regime * Phase control of the intermittency after the crisis * Phase control of the intermittency in the quadratic map * Phase Control of Escapes in Open Dynamical Systems * Control of open dynamical systems * Model description * Numerical simulations and heuristic arguments * Experimental implementation in an electronic circuit * Conclusions and Discussions * Acknowledgments * References
Cosmological phase transitions
International Nuclear Information System (INIS)
Kolb, E.W.
1987-01-01
If the universe stated from conditions of high temperature and density, there should have been a series of phase transitions associated with spontaneous symmetry breaking. The cosmological phase transitions could have observable consequences in the present Universe. Some of the consequences including the formation of topological defects and cosmological inflation are reviewed here. One of the most important tools in building particle physics models is the use of spontaneous symmetry breaking (SSB). The proposal that there are underlying symmetries of nature that are not manifest in the vacuum is a crucial link in the unification of forces. Of particular interest for cosmology is the expectation that are the high temperatures of the big bang symmetries broken today will be restored, and that there are phase transitions to the broken state. The possibility that topological defects will be produced in the transition is the subject of this section. The possibility that the Universe will undergo inflation in a phase transition will be the subject of the next section. Before discussing the creation of topological defects in the phase transition, some general aspects of high-temperature restoration of symmetry and the development of the phase transition will be reviewed. 29 references, 1 figure, 1 table
Electron microscope phase enhancement
Jin, Jian; Glaeser, Robert M.
2010-06-15
A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.
Electron Holography: phases matter.
Lichte, Hannes
2013-06-01
Essentially, all optics is wave optics, be it with light, X-rays, neutrons or electrons. The information transfer from the object to the image can only be understood in terms of waves given by amplitude and phase. However, phases are difficult to measure: for slowly oscillating waves such as sound or low-frequency electromagnetic waves, phases can be measured directly; for high frequencies this has to be done by heterodyne detection, i.e. superposition with a reference and averaging over time. In optics, this is called interferometry. Because interference is mostly very difficult to achieve, phases have often been considered 'hidden variables' seemingly pulling the strings from backstage, only visible by their action on the image intensity. This was almost the case in conventional Electron Microscopy with the phase differences introduced by an object. However, in the face of the urgent questions from solid state physics and materials science, these phases have to be determined precisely, because they encode the most dominant object properties, such as charge distributions and electromagnetic fields. After more than six decades of very patient advancement, electron interferometry and holography offer unprecedented analytical facilities down to an atomic scale. Akira Tonomura has prominently contributed to the present state.
Vapor Compressor Driven Hybrid Two-Phase Loop, Phase I
National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will demonstrate a vapor compressor driven hybrid two-phase loop technology. The hybrid two-phase loop...
Anomaly manifestation of Lieb-Schultz-Mattis theorem and topological phases
Cho, Gil Young; Hsieh, Chang-Tse; Ryu, Shinsei
2017-11-01
The Lieb-Schultz-Mattis (LSM) theorem dictates that emergent low-energy states from a lattice model cannot be a trivial symmetric insulator if the filling per unit cell is not integral and if the lattice translation symmetry and particle number conservation are strictly imposed. In this paper, we compare the one-dimensional gapless states enforced by the LSM theorem and the boundaries of one-higher dimensional strong symmetry-protected topological (SPT) phases from the perspective of quantum anomalies. We first note that they can both be described by the same low-energy effective field theory with the same effective symmetry realizations on low-energy modes, wherein non-on-site lattice translation symmetry is encoded as if it were an internal symmetry. In spite of the identical form of the low-energy effective field theories, we show that the quantum anomalies of the theories play different roles in the two systems. In particular, we find that the chiral anomaly is equivalent to the LSM theorem, whereas there is another anomaly that is not related to the LSM theorem but is intrinsic to the SPT states. As an application, we extend the conventional LSM theorem to multiple-charge multiple-species problems and construct several exotic symmetric insulators. We also find that the (3+1)d chiral anomaly provides only the perturbative stability of the gaplessness local in the parameter space.
Aerospace Systems Monitor, Phase II
National Aeronautics and Space Administration — Proposal Title: Aerospace Systems Monitor PHASE 1 Technical Abstract: This Phase II STTR project will continue development and commercialization of the Aerospace...
DEFF Research Database (Denmark)
Khandige, Surabhi; Møller-Jensen, Jakob
2016-01-01
Surface fimbriae of pathogenic Escherichia coli facilitate sensing, adhesion and even invasion of host epithelial cells. While it is known that the pathogen has the potential to express a plethora of fimbrial variants susceptible to rapid phase ON/OFF variation, it is an open question if the fimb......Surface fimbriae of pathogenic Escherichia coli facilitate sensing, adhesion and even invasion of host epithelial cells. While it is known that the pathogen has the potential to express a plethora of fimbrial variants susceptible to rapid phase ON/OFF variation, it is an open question...... if the fimbrial diversity seen at the population level is the product of random stochasticity or a concerted effort based on active communication. Here we discuss the possibility of a mechanism alternative to a stochastic fimbrial phase variation model affecting the dynamics of a heterogeneous population....
Energy Technology Data Exchange (ETDEWEB)
Gulminelli, F
2003-05-01
In this work the general theory of first order phase transitions in finite systems is discussed, with a special emphasis to the conceptual problems linked to a thermodynamic description for small, short-lived systems de-exciting in the vacuum as nuclear samples coming from heavy ion collisions. After a short review of the general theory of phase transitions in the framework of information theory; we will present the different possible extensions to the field of finite systems. The concept of negative heat capacity, developed in the early seventies in the context of self-gravitating systems, will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. A careful study of the thermodynamic limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. In the second part of the paper we will apply the theoretical ideas developed in the first part to the possible observation of a liquid-to-gas-like phase transition in heavy ion collisions. The applicability of equilibrium concepts in a dynamical collisional process without boundary conditions will first be critically discussed. The observation of abnormally large partial energy fluctuations in carefully selected samples of collisions detected with the MULTICS-Miniball array will then be reported as a strong evidence of a first order phase transition with negative heat capacity in the nuclear equation of state. (author)
International Nuclear Information System (INIS)
Anderson, G.W.
1991-01-01
An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, left-angle φ right-angle T is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of left-angle φ right-angle T . In very minimal extensions of the standard model it is quite easy to increase left-angle φ right-angle T so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value left-angle φ right-angle = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state left-angle φ right-angle = 246 GeV unstable. The requirement that the state left-angle φ right-angle = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field
Compressive Phase Contrast Tomography
International Nuclear Information System (INIS)
Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao
2010-01-01
When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).
Bowers, Michael T
1979-01-01
Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well
Čermák, J
2008-01-01
This special-topic book, devoted to ""Solid Phase Transformations"" , covers a broad range of phenomena which are of importance in a number of technological processes. Most commercial alloys undergo thermal treatment after casting, with the aim of imparting desired compositions and/or optimal morphologies to the component phases. In spite of the fact that the topic has lain at the center of physical metallurgy for a long time, there are numerous aspects which are wide open to potential investigative breakthroughs. Materials with new structures also stimulate research in the field, as well as n
Kopaev, YuV
1992-01-01
Electronic Phase Transitions deals with topics, which are presently at the forefront of scientific research in modern solid-state theory. Anderson localization, which has fundamental implications in many areas of solid-state physics as well as spin glasses, with its influence on quite different research activities such as neural networks, are two examples that are reviewed in this book. The ab initio statistical mechanics of structural phase transitions is another prime example, where the interplay and connection of two unrelated disciplines of solid-state theory - first principle ele
Detecting phase synchronization between coupled non-phase-coherent oscillators
International Nuclear Information System (INIS)
Follmann, Rosangela; Macau, Elbert E.N.; Rosa, Epaminondas
2009-01-01
We compare two methods for detecting phase synchronization in coupled non-phase-coherent oscillators. One method is based on the locking of self-sustained oscillators with an irregular signal. The other uses trajectory recurrences in phase space. We identify the pros and cons of both methods and propose guidelines to detect phase synchronization in data series.
Stochastic modelling of two-phase flows including phase change
International Nuclear Information System (INIS)
Hurisse, O.; Minier, J.P.
2011-01-01
Stochastic modelling has already been developed and applied for single-phase flows and incompressible two-phase flows. In this article, we propose an extension of this modelling approach to two-phase flows including phase change (e.g. for steam-water flows). Two aspects are emphasised: a stochastic model accounting for phase transition and a modelling constraint which arises from volume conservation. To illustrate the whole approach, some remarks are eventually proposed for two-fluid models. (authors)
de Boer, J.; Papadodimas, K.; Verlinde, E.
2009-01-01
Supersymmetric black holes are characterized by a large number of degenerate ground states. We argue that these black holes, like other quantum mechanical systems with such a degeneracy, are subject to a phenomenon which is called the geometric or Berry’s phase: under adiabatic variations of the
International Nuclear Information System (INIS)
Jonah, C.D.; Andong Liu; Mulac, W.A.
1987-01-01
Gas phase pulse radiolysis, a technique which can be used to study many different phenomena in chemistry and physics, is discussed. As a source of small radicals, pulse radiolysis is important to the field of chemistry, particularly to combustion and atmospheric kinetics. The reactions of 1,3-butadiene, allene, ethylene and acetylene with OH are presented. 52 refs., 1 fig., 1 tab
Directory of Open Access Journals (Sweden)
Nobuyuki Kenmochi
1996-01-01
w is constrained to have double obstacles σ*≤w≤σ* (i.e., σ* and σ* are the threshold values of w. The objective of this paper is to discuss the semigroup {S(t} associated with the phase separation model, and construct its global attractor.
International Nuclear Information System (INIS)
Chizhov, A.V.; Paris, M.G.A.
1998-01-01
Phase squeezed states of a single mode radiation field have been introduced as eigenstates of a linear combination of lowering and raising operators. The explicit expression in the Fock basis has been obtained and some relevant properties have been illustrated. (author)
DEFF Research Database (Denmark)
Margheritini, Lucia; Taraborrelli, Valeria Taraborrelli
Margheritini and Valeria Taraborrelli(valeria.taraborrelli@hotmail.it) with a total of 3 day visit from the developers. Laboratory tests in irregular waves will be performed by Lucia Margheritini. The report is aimed at the first stage testing of the Rolling Cylinder wave energy device. This phase includes...
Indian Academy of Sciences (India)
The ferroelectric phase transition is diffuse in nature and broadening of the peak increases with La content. Keywords. PLZT ... Marssi et al (1998) concluded the PLZTs x/65/35 as a model. ∗ ... by analysing field cooled (FC) and zero field cooled (ZFC) dielectric ... material are fitted with universal dielectric behaviour within.
DEFF Research Database (Denmark)
Carlsen, Lars; Egsgaard, Helge
1982-01-01
The unimolecular gas-phase thermolyses of 1,2,3-oxadithiolan 2-oxide and thiiran 1-oxide have been studied by the flash vacuum thermolysis–field ionization mass spectrometry (f.v.t.–f.i.m.s.) technique in the temperature range from 1 043 to 1 404 K. The reactions are rationalized in terms of sulp...
DEFF Research Database (Denmark)
Carlsen, Lars; Egsgaard, Helge
1982-01-01
The unimolecular gas-phase thermolyses of the four methyl and ethyl monothioacetates (5)–(8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range 883–1 404 K. The types of reactions verified were keten formation, thiono–thiolo rea...
DEFF Research Database (Denmark)
Boone, Aaron; de Rosnay, Patricia; Beljaars, Anton
This report describes the experimental setup and results of the Phase 1 (i.e. the Regional Scale) of the AMMA (African Monsoon Multidisciplinary Analysis) Land surface Model Intercomparison Project (ALMIP). It is part of the AMMA-EU (European Union) and API (Action Programmée Interorganisme...
International Nuclear Information System (INIS)
Cohen, A.
2001-01-01
Phasing of two proteins, the 17 kDa Fe protein myoglobin from sperm whale (P. catodon) and an 18 kDa protein (SP18) from green abalone (H. fulgens), using Kr-edge MAD with frozen crystals demonstrates the feasibility of this technique as a routine method for structure determination
Phase transitions in nuclear physics
Energy Technology Data Exchange (ETDEWEB)
Moretto, L.G.; Phair, L.; Wozniak, G.J.
1997-08-01
A critical overview of the low energy phase transitions in nuclei is presented with particular attention to the 2nd (1st) order pairing phase transitions, and to the 1st order liquid-vapor phase transition. The role of fluctuations in washing out these transitions is discussed and illustrated with examples. A robust indicator of phase coexistence in multifragmentation is presented.
Phase transitions in nuclear physics
International Nuclear Information System (INIS)
Moretto, L.G.; Phair, L.; Wozniak, G.J.
1997-08-01
A critical overview of the low energy phase transitions in nuclei is presented with particular attention to the 2nd (1st) order pairing phase transitions, and to the 1st order liquid-vapor phase transition. The role of fluctuations in washing out these transitions is discussed and illustrated with examples. A robust indicator of phase coexistence in multifragmentation is presented
Energy Technology Data Exchange (ETDEWEB)
Schuknecht, Nate [Project Manager; White, David [Principle Investigator; Hoste, Graeme [Research Engineer
2014-09-11
The SkyTrough DSP will advance the state-of-the-art in parabolic troughs for utility applications, with a larger aperture, higher operating temperature, and lower cost. The goal of this project was to develop a parabolic trough collector that enables solar electricity generation in the 2020 marketplace for a 216MWe nameplate baseload power plant. This plant requires an LCOE of 9¢/kWhe, given a capacity factor of 75%, a fossil fuel limit of 15%, a fossil fuel cost of $6.75/MMBtu, $25.00/kWht thermal storage cost, and a domestic installation corresponding to Daggett, CA. The result of our optimization was a trough design of larger aperture and operating temperature than has been fielded in large, utility scale parabolic trough applications: 7.6m width x 150m SCA length (1,118m2 aperture), with four 90mm diameter × 4.7m receivers per mirror module and an operating temperature of 500°C. The results from physical modeling in the System Advisory Model indicate that, for a capacity factor of 75%: The LCOE will be 8.87¢/kWhe. SkyFuel examined the design of almost every parabolic trough component from a perspective of load and performance at aperture areas from 500 to 2,900m2. Aperture-dependent design was combined with fixed quotations for similar parts from the commercialized SkyTrough product, and established an installed cost of $130/m2 in 2020. This project was conducted in two phases. Phase I was a preliminary design, culminating in an optimum trough size and further improvement of an advanced polymeric reflective material. This phase was completed in October of 2011. Phase II has been the detailed engineering design and component testing, which culminated in the fabrication and testing of a single mirror module. Phase II is complete, and this document presents a summary of the comprehensive work.
Phase estimation in optical interferometry
Rastogi, Pramod
2014-01-01
Phase Estimation in Optical Interferometry covers the essentials of phase-stepping algorithms used in interferometry and pseudointerferometric techniques. It presents the basic concepts and mathematics needed for understanding the phase estimation methods in use today. The first four chapters focus on phase retrieval from image transforms using a single frame. The next several chapters examine the local environment of a fringe pattern, give a broad picture of the phase estimation approach based on local polynomial phase modeling, cover temporal high-resolution phase evaluation methods, and pre
International Nuclear Information System (INIS)
Hsu, Y.Y.
1974-01-01
The following papers related to two-phase flow are summarized: current assumptions made in two-phase flow modeling; two-phase unsteady blowdown from pipes, flow pattern in Laval nozzle and two-phase flow dynamics; dependence of radial heat and momentum diffusion; transient behavior of the liquid film around the expanding gas slug in a vertical tube; flooding phenomena in BWR fuel bundles; and transient effects in bubble two-phase flow. (U.S.)
Measurement by phase severance
International Nuclear Information System (INIS)
Noyes, H.P.
1987-03-01
It is claimed that the measurement process is more accurately described by ''quasi-local phase severance'' than by ''wave function collapse''. The approach starts from the observation that the usual route to quantum mechanics starting from the Hamilton-Jacobi equations throws away half the degrees of freedom, namely, the classical initial state parameters. To overcome this difficulty, the full set of Hamilton-Jacobi equations is interpreted as operator equations acting on a state vector. The measurement theory presented is based on the conventional S-matrix boundary condition of N/sub A/ free particles in the distant past and N/sub B/ free particles in the distant future and taking the usual free particle wave functions, multiplied by phase factors
Pawliszyn, J
2001-01-01
Solid Phase Microextraction (SPME) uses a small volume of sorbent dispersed typically on the surface of small fibres, to isolate and concentrate analytes from sample matrix. After contact with sample, analytes are absorbed or adsorbed by the fibre phase (depending on the nature of the coating) until an equilibrium is reached in the system. The amount of an analyte extracted by the coating at equilibrium is determined by the magnitude of the partition coefficient of the analyte between the sample matrix and the coating material. After the extraction step, the fibres are transferred, with the help of a syringe-like handling device, to analytical instrument, for separation and quantitation of target analytes. This technique integrates sampling, extraction and sample introduction and is a simple way of facilitating on-site monitoring. Applications of this technique include environmental monitoring, industrial hygiene, process monitoring, clinical, forensic, food, flavour, fragrance and drug analyses, in laboratory and on-site analysis.
International Nuclear Information System (INIS)
1989-01-01
The International Thermonuclear Experimental Reactor (ITER) is envisioned as a fusion device which would demonstrate the scientific and technological feasibility of fusion power. As a first step towards achieving this goal, the European Community, Japan, the Soviet Union, and the United States of America have entered into joint conceptual design activities under the auspices of the International Atomic Energy Agency. A brief summary of the Definition Phase of ITER activities is contained in this report. Included in this report are the background, objectives, organization, definition phase activities, and research and development plan of this endeavor in international scientific collaboration. A more extended technical summary is contained in the two-volume report, ''ITER Concept Definition,'' IAEA/ITER/DS/3. 2 figs, 2 tabs
Discommensurates and incommensurate phases
International Nuclear Information System (INIS)
Gordon, Mirta Beatriz
1983-01-01
In its first part, this research thesis reports the study of the commensurate-incommensurate (C-I) transition of single layers of rare gases adsorbed on graphite. The anharmonicity of the interaction between adatoms could explain experimental results corresponding to krypton. The author also studied the orientation instability of the single layer with respect to the chemical potential. Near the C-I transition, walls or discommensurates are oriented in substrate symmetry directions which are determined. The effect of substrate deformation on C-I transition is also studied. In the second part, the author studied the phase diagram at low temperature of the anisotropic Ising model with competing interactions for the approximation of the mean field. Finally, the author presents a phenomenological model of Cerium Antimony which reproduces a large part of its phase diagram [fr
Phases, phase equilibria, and phase rules in low-dimensional systems
International Nuclear Information System (INIS)
Frolov, T.; Mishin, Y.
2015-01-01
We present a unified approach to thermodynamic description of one, two, and three dimensional phases and phase transformations among them. The approach is based on a rigorous definition of a phase applicable to thermodynamic systems of any dimensionality. Within this approach, the same thermodynamic formalism can be applied for the description of phase transformations in bulk systems, interfaces, and line defects separating interface phases. For both lines and interfaces, we rigorously derive an adsorption equation, the phase coexistence equations, and other thermodynamic relations expressed in terms of generalized line and interface excess quantities. As a generalization of the Gibbs phase rule for bulk phases, we derive phase rules for lines and interfaces and predict the maximum number of phases than may coexist in systems of the respective dimensionality
Solid phase extraction membrane
Carlson, Kurt C [Nashville, TN; Langer, Roger L [Hudson, WI
2002-11-05
A wet-laid, porous solid phase extraction sheet material that contains both active particles and binder and that possesses excellent wet strength is described. The binder is present in a relatively small amount while the particles are present in a relatively large amount. The sheet material is sufficiently strong and flexible so as to be pleatable so that, for example, it can be used in a cartridge device.
Phase controlled rectifier study
International Nuclear Information System (INIS)
Bronner, G.; Murray, J.G.
1976-03-01
This report introduces the results of an engineering study incorporating a computer program to determine the transient and steady-state voltage and current wave shapes for a 12-pulse rectifier system. Generally, rectifier engineering studies are completed by making simplified assumptions and neglecting many circuit parameters. The studies incorporate the 3-phase AC parameters including nonlinear source or generator, 3-winding transformer impedances, and shunt and series capacitors. It includes firing angle control, and DC filter circuits with inductive loads
Phase Transitions in Geomorphology
Ortiz, C. P.; Jerolmack, D. J.
2015-12-01
Landscapes are patterns in a dynamic steady-state, due to competing processes that smooth or sharpen features over large distances and times. Geomorphic transport laws have been developed to model the mass-flux due to different processes, but are unreasonably effective at recovering the scaling relations of landscape features. Using a continuum approximation to compare experimental landscapes and the observed landscapes of the earth, one finds they share similar morphodynamics despite a breakdown of classical dynamical similarity between the two. We propose the origin of this effectiveness is a different kind of dynamic similarity in the statistics of initiation and cessation of motion of groups of grains, which is common to disordered systems of grains under external driving. We will show how the existing data of sediment transport points to common signatures with dynamical phase transitions between "mobile" and "immobile" phases in other disordered systems, particularly granular materials, colloids, and foams. Viewing landscape evolution from the lens of non-equilibrium statistical physics of disordered systems leads to predictions that the transition of bulk measurements such as particle flux is continuous from one phase to another, that the collective nature of the particle dynamics leads to very slow aging of bulk properties, and that the dynamics are history-dependent. Recent results from sediment transport experiments support these predictions, suggesting that existing geomorphic transport laws may need to be replaced by a new generation of stochastic models with ingredients based on the physics of disordered phase transitions. We discuss possible strategies for extracting the necessary information to develop these models from measurements of geomorphic transport noise by connecting particle-scale collective dynamics and space-time fluctuations over landscape features.
DEFF Research Database (Denmark)
Carlsen, Lars; Egsgaard, Helge; Schaumann, Ernst
1980-01-01
The unimolecular gas-phase thermolytic decomposition of three silylated thionocarboxylic acid derivatives (2b), (3), and (8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range from 783 to 1 404 K in order to elucidate its possible...... applicability as a route to thioketens. Only very minor amounts of the expected thioketens were found, whereas the corresponding ketens were obtained as the major products. A possible mechanism for keten formation is discussed....
Phases and phase transitions of S=1 bosons
Indian Academy of Sciences (India)
smukerjee
Quantum phases and phase transitions of bosons. Subroto Mukerjee. Dept. of Physics & Centre for Quantum. Information and Quantum Computing (CQIQC). Indian Institute of Science, Bangalore. 77th annual meeting of the IAS, Nov. 20 2011, PRL Ahmedabad ...
Qualitative behaviour of incompressible two-phase flows with phase ...
Indian Academy of Sciences (India)
Jan Prüss
2017-11-07
Nov 7, 2017 ... Qualitative behaviour of incompressible two-phase flows with phase ... Germany. 2Graduate School of Human and Environmental Studies, Kyoto University, ... Note that j is a dummy variable as it can be eliminated from the ...
Phase separation and shape deformation of two-phase membranes
International Nuclear Information System (INIS)
Jiang, Y.; Lookman, T.; Saxena, A.
2000-01-01
Within a coupled-field Ginzburg-Landau model we study analytically phase separation and accompanying shape deformation on a two-phase elastic membrane in simple geometries such as cylinders, spheres, and tori. Using an exact periodic domain wall solution we solve for the shape and phase separating field, and estimate the degree of deformation of the membrane. The results are pertinent to preferential phase separation in regions of differing curvature on a variety of vesicles. (c) 2000 The American Physical Society
Analyzing phase diagrams and phase transitions in networked competing populations
Ni, Y.-C.; Yin, H. P.; Xu, C.; Hui, P. M.
2011-03-01
Phase diagrams exhibiting the extent of cooperation in an evolutionary snowdrift game implemented in different networks are studied in detail. We invoke two independent payoff parameters, unlike a single payoff often used in most previous works that restricts the two payoffs to vary in a correlated way. In addition to the phase transition points when a single payoff parameter is used, phase boundaries separating homogeneous phases consisting of agents using the same strategy and a mixed phase consisting of agents using different strategies are found. Analytic expressions of the phase boundaries are obtained by invoking the ideas of the last surviving patterns and the relative alignments of the spectra of payoff values to agents using different strategies. In a Watts-Strogatz regular network, there exists a re-entrant phenomenon in which the system goes from a homogeneous phase into a mixed phase and re-enters the homogeneous phase as one of the two payoff parameters is varied. The non-trivial phase diagram accompanying this re-entrant phenomenon is quantitatively analyzed. The effects of noise and cooperation in randomly rewired Watts-Strogatz networks are also studied. The transition between a mixed phase and a homogeneous phase is identify to belong to the directed percolation universality class. The methods used in the present work are applicable to a wide range of problems in competing populations of networked agents.
Phase sensitive multichannel OCT
International Nuclear Information System (INIS)
Trasischker, W.
2015-01-01
The main aim of this thesis was to develop and improve phase sensitive, multichannel methods for optical coherence tomography (OCT) using light in the 840 nm and 1040 nm regime. Conventional OCT provides purely structural information by illuminating the sample by one beam and recording the backscattered signal with one detection channel. Combination of this approach with a raster scan enables the acquisition of 2D and 3D structural information with a resolution in the micrometer regime. However, sometimes additional image contrast or information is desired. Amongst other approaches, this can be provided by a phase sensitive analysis of the interference pattern. Combining phase sensitivity with the illumination of the sample by more than one beam and/or by recording the data using more than one data acquisition channel allows for even more enhanced imaging. While phase sensitive OCT gives access to additional contrast and information, multichannel OCT can provide higher imaging speed, scan eld size and exible dierential measurements. Amongst the dierential, phase sensitive approaches, Doppler OCT (DOCT) and polarization sensitive OCT (PS-OCT) are two of the most promising OCT modalities. While the former targets information on the movement of backscattering particles, the latter measures alterations of the polarization state of the light induced by the sample. Both techniques provide additional image contrast and are, due to the non-invasive and fast character of OCT, well suited for in vivo imaging of the human eye. In the course of this thesis, two dierent multichannel, phase sensitive OCT systems will be presented. First, a D-OCT system with three dierent sampling beams is described. With a central wavelength of 840 nm these three beams are emitted by three individual laser sources. This eectively eliminates any cross talk and provides the full depth range for each channel. Furthermore, by illuminating the sample from three dierent directions, the absolute
Qureshi, Moinuddin K
2011-01-01
As conventional memory technologies such as DRAM and Flash run into scaling challenges, architects and system designers are forced to look at alternative technologies for building future computer systems. This synthesis lecture begins by listing the requirements for a next generation memory technology and briefly surveys the landscape of novel non-volatile memories. Among these, Phase Change Memory (PCM) is emerging as a leading contender, and the authors discuss the material, device, and circuit advances underlying this exciting technology. The lecture then describes architectural solutions t
International Nuclear Information System (INIS)
Reese, M.G.; Johnson, L.R.; Ransom, D.K.
1980-01-01
In a solid phase assay for quantitative determination of biological and other analytes, a sample such as serum is contacted with a receptor for the analyte being assayed, the receptor being supported on a solid support. No tracer for the analyte is added to the sample before contacting with the receptor; instead the tracer is contacted with the receptor after unbound analyte has been removed from the receptor. The assay can be otherwise performed in a conventional manner but can give greater sensitivity. (author)
Incommensurate phase transitions
Energy Technology Data Exchange (ETDEWEB)
Currat, R [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)
1996-11-01
We review the characteristic aspects of modulated crystals from the point of view of inelastic neutron scattering. We discuss the phenomenological Landau theory of the normal-to-incommensurate displacive instability and its predictions concerning the fluctuation spectrum of the modulated phase. General results on the form of the normal-mode eigenvectors and on the inelastic scattering channels through which they couple to the probe are established using the superspace approach. We illustrate these results on a simple discrete model symmetry and we review available inelastic neutron scattering data on several displacively modulated compounds. (author) 21 figs., 73 refs.
Selected cerium phase diagrams
International Nuclear Information System (INIS)
Gschneidner, K.A. Jr.; Verkade, M.E.
1974-09-01
A compilation of cerium alloy phase equilibria data based on the most reliable information available is presented. The binary systems selected are those of cerium with each of the following twenty nine elements which might be commonly found in steels: Al, Sb, As, Bi, Ca, C, Cr, Co, Nb, Cu, Fe, Pb, Mg, Mn, Mo, Ni, N, O, P, Se, Si, Ag, S, Te, Sn, Ti, W, and Zn. A brief discussion, a summary of crystal lattice parameters where applicable, and a list of references is included for each element surveyed. (U.S.)
Microcellular foams via phase separation
International Nuclear Information System (INIS)
Young, A.T.
1985-01-01
A study of wide variety of processes for making plastic foams shows that phase separation processes for polymers from solutions offers the most viable methods for obtaining rigid plastic foams which met the physical requirements for fusion target designs. Four general phase separation methods have been shown to give polymer foams with densities less than 0.1 g/cm 3 and cell sizes of 30μm or less. These methods involve the utilization of non-solvent, chemical or thermal cooling processes to achieve a controlled phase separation wherein either two distinct phases are obtained where the polymer phase is a continuous phase or two bicontinuous phases are obtained where both the polymer and solvent are interpenetrating, continuous, labyrinthine phases. Subsequent removal of the solvent gives the final foam structure
Indicators of Indiscipline. Phase 2
National Research Council Canada - National Science Library
Owens, S
1991-01-01
.... Phase 2 research was conducted to determine which of the indicators identified by the phase 1 study could successfully identify soldiers who cause accidents due to indiscipline and to field test...
Phase diagrams of the elements
International Nuclear Information System (INIS)
Young, D.A.
1975-01-01
A summary of the pressure-temperature phase diagrams of the elements is presented, with graphs of the experimentally determined solid-solid phase boundaries and melting curves. Comments, including theoretical discussion, are provided for each diagram. The crystal structure of each solid phase is identified and discussed. This work is aimed at encouraging further experimental and theoretical research on phase transitions in the elements
Exotic phases in neutron stars
International Nuclear Information System (INIS)
Li, A.; Burgio, G.F.; Lombardo, U.; Peng, G.X.
2008-01-01
The appearance of exotic phases in neutron stars is studied. The possible transition from hadron to quark phase is studied within the density dependent mass quark model, and the kaon condensation within the Nelson and Kaplan model. In both cases a microscopic approach is adopted for dense hadron matter. From the study of the possible coexistence between the two phases it is found that the hybrid phase may strongly hinder the onset of kaon condensation. (author)
Phase Referencing in Optical Interferometry
Filho, Mercedes E.; Garcia, Paulo; Duvert, Gilles; Duchene, Gaspard; Thiebaut, Eric; Young, John; Absil, Olivier; Berger, Jean-Phillipe; Beckert, Thomas; Hoenig, Sebastian; Schertl, Dieter; Weigelt, Gerd; Testi, Leonardo; Tatuli, Eric; Borkowski, Virginie
2008-01-01
One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce...
The nuclear liquid gas phase transition and phase coexistence
International Nuclear Information System (INIS)
Chomaz, Ph.
2001-01-01
In this talk we will review the different signals of liquid gas phase transition in nuclei. From the theoretical side we will first discuss the foundations of the concept of equilibrium, phase transition and critical behaviors in infinite and finite systems. From the experimental point of view we will first recall the evidences for some strong modification of the behavior of hot nuclei. Then we will review quantitative detailed analysis aiming to evidence phase transition, to define its order and phase diagram. Finally, we will present a critical discussion of the present status of phase transitions in nuclei and we will draw some lines for future development of this field. (author)
The nuclear liquid gas phase transition and phase coexistence
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph
2001-07-01
In this talk we will review the different signals of liquid gas phase transition in nuclei. From the theoretical side we will first discuss the foundations of the concept of equilibrium, phase transition and critical behaviors in infinite and finite systems. From the experimental point of view we will first recall the evidences for some strong modification of the behavior of hot nuclei. Then we will review quantitative detailed analysis aiming to evidence phase transition, to define its order and phase diagram. Finally, we will present a critical discussion of the present status of phase transitions in nuclei and we will draw some lines for future development of this field. (author)
Unwrapping the Bundle: An Examination of Research Libraries and the "Big Deal"
Strieb, Karla L.; Blixrud, Julia C.
2014-01-01
This study presents and analyzes the findings of a 2012 survey of member libraries belonging to the Association of Research Libraries (ARL) about publishers' large journal bundles and compares the results to earlier surveys. The data illuminate five research questions: market penetration, journal bundle construction, collection format shifts,…
Heeding the waveform inversion nonlinearity by unwrapping the model and data
Alkhalifah, Tariq Ali; Choi, Yun Seok
2012-01-01
Unlike traveltime inversion, waveform inversion provides relatively higher-resolution inverted models. This feature, however, comes at the cost of introducing complex nonlinearity to the inversion operator complicating the convergence process. We
Kammeyer-Mueller, John D; Wanberg, Connie R
2003-10-01
This 4-wave longitudinal study of newcomers in 7 organizations examined preentry knowledge, proactive personality, and socialization influences as antecedents of both proximal (task mastery, role clarity, work group integration, and political knowledge) and distal (organizational commitment, work withdrawal, and turnover) indicators of newcomer adjustment. Results suggest that preentry knowledge, proactive personality, and socialization influences from the organization, supervisors, and coworkers are independently related to proximal adjustment outcomes, consistent with a theoretical framework highlighting distinct dimensions of organizational and work task adjustment. The proximal adjustment outcomes partially mediated most of the relationships between the antecedents of adjustment and organizational commitment, work withdrawal, and turnover.
Phase-change materials handbook
Hale, D. V.; Hoover, M. J.; Oneill, M. J.
1972-01-01
Handbook describes relationship between phase-change materials and more conventional thermal control techniques and discusses materials' space and terrestrial applications. Material properties of most promising phase-change materials and purposes and uses of metallic filler materials in phase-change material composites are provided.
Phase strength and super lattices
Indian Academy of Sciences (India)
Unknown
much below the solubility limit, so that the short chain molecules do not behave as solvent molecules). Therefore enhanced phase separation and lesser incorporation of. C10-ol (which is however still higher than the value at point B) is responsible for the formation of relatively lesser βo phase and more βm phase at MR ...
International Nuclear Information System (INIS)
Brykina, G.D.; Marchenko, D.Yu.; Shpigun, O.A.
1995-01-01
Solid-phase spectrophotometry (SPS), which is based on the direct measurement of light absorption of an ion exchanger containing a substance of interest, was reviewed. Since 1976, it has been known that aborbance of an ion exchanger is directly proportional to the concentration of a particular ion in solution. A similar dependence can also be followed for other sorbents, as well as for foams, membranes, films, etc., which do not exhibit ion exchange properties. One can use absorption, diffuse reflection, and luminescence spectra parameters as an analytical signal. Thus, SPS of ion exchangers is among the analytical techniques that combine the sorption concentration and surface determination of the substance of interest. This review summarizes the advancements in SPS over the last six years and demonstrates the prospects for its development. Special attention is paid to experimental methods for measuring solid-phase absorption and to the basic procedures of sample preparation, including new ones. These two facets are of great importance for obtaining precise results and extending the capabilities of SPS
Energy Technology Data Exchange (ETDEWEB)
Roessner, Simon
2009-04-09
Quantum Chromodynamics (QCD) is the theory of the strong interaction within the Standard Model of elementary particles. Today's research in this area dedicates substantial resources to numeric solutions of the QCD field equations and experimental programs exploring the phases of QCD. This thesis proceeds along a complementary line - that of modelling QCD, with the aim of identifying its dominant degrees of freedom. This is possible by minimally coupling effective potentials for the Polyakov loop to Nambu-Jona-Lasinio models using temporal background fields to model chiral symmetry breaking respecting colour confinement. The fermion sign problem resulting from the minimal coupling is addressed in this work establishing a novel, systematically ordered approach. The modifications to the approximative order parameter of colour confinement, the Polyakov loop, are in direct connection with the fermion sign problem. Furthermore an effective coupling of quark densities of different flavours is induced. This mechanism, most likely also present in QCD, produces finite contributions to flavour off diagonal susceptibilities. Susceptibilities are amongst the most promising physical quantities for the experimental exploration of the phase transition at high temperatures and densities. (orig.)
International Nuclear Information System (INIS)
Roessner, Simon
2009-01-01
Quantum Chromodynamics (QCD) is the theory of the strong interaction within the Standard Model of elementary particles. Today's research in this area dedicates substantial resources to numeric solutions of the QCD field equations and experimental programs exploring the phases of QCD. This thesis proceeds along a complementary line - that of modelling QCD, with the aim of identifying its dominant degrees of freedom. This is possible by minimally coupling effective potentials for the Polyakov loop to Nambu-Jona-Lasinio models using temporal background fields to model chiral symmetry breaking respecting colour confinement. The fermion sign problem resulting from the minimal coupling is addressed in this work establishing a novel, systematically ordered approach. The modifications to the approximative order parameter of colour confinement, the Polyakov loop, are in direct connection with the fermion sign problem. Furthermore an effective coupling of quark densities of different flavours is induced. This mechanism, most likely also present in QCD, produces finite contributions to flavour off diagonal susceptibilities. Susceptibilities are amongst the most promising physical quantities for the experimental exploration of the phase transition at high temperatures and densities. (orig.)
2006-01-01
This month has seen the launch of the second two-year phase of the Enabling Grids for E-sciencE project (EGEE-II), with a transition meeting for the partners held at CERN on 12-13 April. Co-funded by the European Commission and coordinated by CERN, the EGEE project is providing an international Grid computing infrastructure - now numbering some 200 sites and 20 000 CPUs in 39 countries - to support the scientific community worldwide. 'We are all very happy about the smooth start of the second phase of EGEE,' said Project Director Bob Jones. 'The project builds on the successes of its first two years and we are now focussing on the stability of the deployed infrastructure. Growing beyond our pilot application areas of HEP and biomedicine, we now see increasing use by researchers from other fields. Recently we've added finance and fusion to the list of disciplines we support, and we are always looking for new users.' More information on EGEE can be found at www.eu-egee.org.
Phase-step retrieval for tunable phase-shifting algorithms
Ayubi, Gastón A.; Duarte, Ignacio; Perciante, César D.; Flores, Jorge L.; Ferrari, José A.
2017-12-01
Phase-shifting (PS) is a well-known technique for phase retrieval in interferometry, with applications in deflectometry and 3D-profiling, which requires a series of intensity measurements with certain phase-steps. Usually the phase-steps are evenly spaced, and its knowledge is crucial for the phase retrieval. In this work we present a method to extract the phase-step between consecutive interferograms. We test the proposed technique with images corrupted by additive noise. The results were compared with other known methods. We also present experimental results showing the performance of the method when spatial filters are applied to the interferograms and the effect that they have on their relative phase-steps.
International Nuclear Information System (INIS)
Delaje, Dzh.
1984-01-01
General hypothesis used to simplify the equations, describing two-phase flows, are considered. Two-component and one-component models of two-phase flow, as well as Zuber and Findlay model for actual volumetric steam content, and Wallis model, describing the given phase rates, are presented. The conclusion is made, that the two-component model, in which values averaged in time are included, is applicable for the solving of three-dimensional tasks for unsteady two-phase flow. At the same time, using the two-component model, including values, averaged in space only one-dimensional tasks for unsteady two-phase flow can be solved
International Nuclear Information System (INIS)
Foxall, W; Vincent, P; Walter, W
1999-01-01
immediate implication of this finding is that underground nuclear explosions may not need to be captured coseismically by radar images acquired before and after an event in order to be detectable. This has obvious advantages in CTBT monitoring since suspect seismic events-which usually can be located within a 100 km by 100 km area of an ERS-1/2 satellite frame by established seismic methods-can be imaged after the event has been identified and located by existing regional seismic networks. Key Words: InSAR, SLC images, interferogram, synthetic interferogram, ERS-1/2 frame, phase unwrapping, DEM, coseismic, postseismic, source parameters
Hockney, Roger
1987-01-01
Algorithmic phase diagrams are a neat and compact representation of the results of comparing the execution time of several algorithms for the solution of the same problem. As an example, the recent results are shown of Gannon and Van Rosendale on the solution of multiple tridiagonal systems of equations in the form of such diagrams. The act of preparing these diagrams has revealed an unexpectedly complex relationship between the best algorithm and the number and size of the tridiagonal systems, which was not evident from the algebraic formulae in the original paper. Even so, for a particular computer, one diagram suffices to predict the best algorithm for all problems that are likely to be encountered the prediction being read directly from the diagram without complex calculation.
International Nuclear Information System (INIS)
Berry, M.V.
2002-01-01
For illumination with white light, the spectra near a typical isolated phase singularity (nodal point of the component wavelengths) can be described by a universal function of position, up to linear distortion and a weak dependence on the spectrum of the source. The appearance of the singularity when viewed by a human observer is predicted by transforming the spectrum to trichromatic variables and chromaticity coordinates, and then rendering the colours, scaled to constant luminosity, on a computer monitor. The pattern far from the singularity is a white that depends on the source temperature, and the centre of the pattern is flanked by intensely coloured 'eyes', one orange and one blue, separated by red, and one of the eyes is surrounded by a bright white circle. Only a small range of possible colours appears near the singularity; in particular, there is no green. (author)
Directory of Open Access Journals (Sweden)
Marco Liuni
2013-08-01
Full Text Available For a broad range of sound transformations, quality is measured according to the common expectation about the result: if a male’s voice has to be changed in a female’s one, there exists a common reference for the perceptive evaluation of the result; the same holds if an instrumental sound has to be made longer, or shorter. Following the argument in Röbel, “Between Physics and Perception: Signal Models for High Level Audio Processing”, a fundamental requirement for these transformation algorithms is their need of signal models that are strongly linked to perceptually relevant physical properties of the sound source. This paper is a short survey about the phase vocoder technique, together with its extensions and improvements relying on appropriate sound models, which have led to high level audio processing algorithms.
International Nuclear Information System (INIS)
Olive, J.
1990-01-01
The design, operation and safety of nuclear components requires increasingly accurate knowledge of two-phase flows. This knowledge is also necessary for some studies related to electricity applications. The author presents some concrete examples showing the range of problems and the complexity of the phenomena involved in these types of flows. Then, the basic principles of their numerical modelling are explained, as well as the new tendency to use increasingly local and refined models. The newest computer codes developed at EDF are briefly presented. Experimental studies dealing with twophase flow are also referred to, and their connections to numerical modelling are explained. Emphasis is placed on the major efforts devoted to the development of new test rigs and instrumentation [fr
DEFF Research Database (Denmark)
Nilsson, Torben
The objective of this study has been to develop new analytical methods using the rapid, simple and solvent-free extraction technique solid-phase microextraction (SPME) for the quantitative analysis of organic pollutants at trace level in drinking water and environmental samples. The dynamics...... of SPME were examined for halogenated and non-halogenated volatile hydrocarbons, and a standard method for their quantitative analysis in aqueous samples was developed and validated in inter-laboratory studies on the basis of reference material and in comparison with the traditional methods....... The influences of some possible interferences on the SPME process were examined, and new SPME probes were tested for the in situ monitoring of groundwater pollutants. Inter-laboratory studies were carried out also for the validation of SPME for the quantitative analysis of organochlorine, organonitrogen...
Phase coexistence in multifragmentation?
International Nuclear Information System (INIS)
Moretto, L.G.; Phair, L.; Ghetti, R.; Tso, K.; Colonna, N.; Skulski, W.; Wozniak, G.J.; Bowman, D.R.; Carlin, N.; Chartier, M.; Gelbke, C.K.; Gong, W.G.; Hsi, W.C.; Kim, Y.D.; Lisa, M.A.; Lynch, W.G.; Peaslee, G.F.; Schwarz, C.; de Souza, R.T.; Tsang, M.B.; Zhu, F.
1996-01-01
The charge (Z) distributions from intermediate energy heavy-ion reactions depend upon the multiplicity n of intermediate mass fragments through a factor of the form e -cnZ . Experimentally c starts from zero at low values of the transverse energy E t and reaches a saturation value at high E t . In a liquid-gas phase diagram c=0 for the saturated vapor, while c approx-gt 0 for the unsaturated vapor. It is suggested that in the c≅0 regime the source evaporates down to a sizable remnant, while for c approx-gt 0 the source vaporizes completely. Percolation of finite systems and nuclear evaporation portray a behavior similar to that observed experimentally. copyright 1996 The American Physical Society
Superconductivity in Chevrel phases
International Nuclear Information System (INIS)
Fischer, O.; Seeber, B.
1979-01-01
In the last years several ternary superconductors have been discovered, which possess unusual physical properties. Among them the molybdenum chalcogenides, which are often called Chevrel phases, have a special position. Some of these compounds have very high critical fields, which is of special interest for a technical application. In these substances the coexistence of magnetic ordering and superconductivity has been found for the first time, too. Recently it has become possible to prepare new compounds, which are interesting for superconductivity, by the appropriate coalescence of Mo 6 clusters. In the case of Tl 2 Mo 6 Se 6 (Tsub(c) = 3K) this development leads to a quasi-one-dimensional metallic system. (orig.)
Energy Technology Data Exchange (ETDEWEB)
R. Wigeland; T. Taiwo; M. Todosow; W. Halsey; J. Gehin
2010-09-01
The Options Study has been conducted for the purpose of evaluating the potential of alternative integrated nuclear fuel cycle options to favorably address the issues associated with a continuing or expanding use of nuclear power in the United States. The study produced information that can be used to inform decisions identifying potential directions for research and development on such fuel cycle options. An integrated nuclear fuel cycle option is defined in this study as including all aspects of the entire nuclear fuel cycle, from obtaining natural resources for fuel to the ultimate disposal of used nuclear fuel (UNF) or radioactive wastes. Issues such as nuclear waste management, especially the increasing inventory of used nuclear fuel, the current uncertainty about used fuel disposal, and the risk of nuclear weapons proliferation have contributed to the reluctance to expand the use of nuclear power, even though it is recognized that nuclear power is a safe and reliable method of producing electricity. In this Options Study, current, evolutionary, and revolutionary nuclear energy options were all considered, including the use of uranium and thorium, and both once-through and recycle approaches. Available information has been collected and reviewed in order to evaluate the ability of an option to clearly address the challenges associated with the current implementation and potential expansion of commercial nuclear power in the United States. This Options Study is a comprehensive consideration and review of fuel cycle and technology options, including those for disposal, and is not constrained by any limitations that may be imposed by economics, technical maturity, past policy, or speculated future conditions. This Phase II report is intended to be used in conjunction with the Phase I report, and much information in that report is not repeated here, although some information has been updated to reflect recent developments. The focus in this Options Study was to
Para-equilibrium phase diagrams
International Nuclear Information System (INIS)
Pelton, Arthur D.; Koukkari, Pertti; Pajarre, Risto; Eriksson, Gunnar
2014-01-01
Highlights: • A rapidly cooled system may attain a state of para-equilibrium. • In this state rapidly diffusing elements reach equilibrium but others are immobile. • Application of the Phase Rule to para-equilibrium phase diagrams is discussed. • A general algorithm to calculate para-equilibrium phase diagrams is described. - Abstract: If an initially homogeneous system at high temperature is rapidly cooled, a temporary para-equilibrium state may result in which rapidly diffusing elements have reached equilibrium but more slowly diffusing elements have remained essentially immobile. The best known example occurs when homogeneous austenite is quenched. A para-equilibrium phase assemblage may be calculated thermodynamically by Gibbs free energy minimization under the constraint that the ratios of the slowly diffusing elements are the same in all phases. Several examples of calculated para-equilibrium phase diagram sections are presented and the application of the Phase Rule is discussed. Although the rules governing the geometry of these diagrams may appear at first to be somewhat different from those for full equilibrium phase diagrams, it is shown that in fact they obey exactly the same rules with the following provision. Since the molar ratios of non-diffusing elements are the same in all phases at para-equilibrium, these ratios act, as far as the geometry of the diagram is concerned, like “potential” variables (such as T, pressure or chemical potentials) rather than like “normal” composition variables which need not be the same in all phases. A general algorithm to calculate para-equilibrium phase diagrams is presented. In the limit, if a para-equilibrium calculation is performed under the constraint that no elements diffuse, then the resultant phase diagram shows the single phase with the minimum Gibbs free energy at any point on the diagram; such calculations are of interest in physical vapor deposition when deposition is so rapid that phase
Sakaguchi, Toshimasa; Fujigaki, Motoharu; Murata, Yorinobu
2015-03-01
Accurate and wide-range shape measurement method is required in industrial field. The same technique is possible to be used for a shape measurement of a human body for the garment industry. Compact 3D shape measurement equipment is also required for embedding in the inspection system. A shape measurement by a phase shifting method can measure the shape with high spatial resolution because the coordinates can be obtained pixel by pixel. A key-device to develop compact equipment is a grating projector. Authors developed a linear LED projector and proposed a light source stepping method (LSSM) using the linear LED projector. The shape measurement euipment can be produced with low-cost and compact without any phase-shifting mechanical systems by using this method. Also it enables us to measure 3D shape in very short time by switching the light sources quickly. A phase unwrapping method is necessary to widen the measurement range with constant accuracy for phase shifting method. A general phase unwrapping method with difference grating pitches is often used. It is one of a simple phase unwrapping method. It is, however, difficult to apply the conventional phase unwrapping algorithm to the LSSM. Authors, therefore, developed an expansion unwrapping algorithm for the LSSM. In this paper, an expansion algorithm of measurement range suited for 3D shape measurement using two pitches of projected grating with the LSSM was evaluated.
Phase equilibria and phase structures of polymer blends
International Nuclear Information System (INIS)
Chalykh, Anatolii E; Gerasimov, Vladimir K
2004-01-01
Experimental, methodical and theoretical studies dealing with phase equilibria and phase structures of polymer blends are generalised. The general and specific features of the change in solubility of polymers with changes in the molecular mass and copolymer composition and upon the formation of three-dimensional cross-linked networks are described. The results of the effect of the prehistory on the phase structure and the non-equilibrium state of polymer blends are considered in detail.
Carlstrom, Nicholas Mercury
2016-01-01
This position with the Simulation and Graphics Branch (ER7) at Johnson Space Center (JSC) provided an introduction to vehicle hardware, mission planning, and simulation design. ER7 supports engineering analysis and flight crew training by providing high-fidelity, real-time graphical simulations in the Systems Engineering Simulator (SES) lab. The primary project assigned by NASA mentor and SES lab manager, Meghan Daley, was to develop a graphical simulation of the rendezvous, proximity operations, and docking (RPOD) phases of flight. The simulation is to include a generic crew/cargo transportation vehicle and a target object in low-Earth orbit (LEO). Various capsule, winged, and lifting body vehicles as well as historical RPOD methods were evaluated during the project analysis phase. JSC core mission to support the International Space Station (ISS), Commercial Crew Program (CCP), and Human Space Flight (HSF) influenced the project specifications. The simulation is characterized as a 30 meter +V Bar and/or -R Bar approach to the target object's docking station. The ISS was selected as the target object and the international Low Impact Docking System (iLIDS) was selected as the docking mechanism. The location of the target object's docking station corresponds with the RPOD methods identified. The simulation design focuses on Guidance, Navigation, and Control (GNC) system architecture models with station keeping and telemetry data processing capabilities. The optical and inertial sensors, reaction control system thrusters, and the docking mechanism selected were based on CCP vehicle manufacturer's current and proposed technologies. A significant amount of independent study and tutorial completion was required for this project. Multiple primary source materials were accessed using the NASA Technical Report Server (NTRS) and reference textbooks were borrowed from the JSC Main Library and International Space Station Library. The Trick Simulation Environment and User
Crystalline liquids: the blue phases
Wright, David C.; Mermin, N. David
1989-04-01
The blue phases of cholesteric liquid crystals are liquids that exhibit orientational order characterized by crystallographic space-group symmetries. We present here a pedagogical introduction to the current understanding of the equilibrium structure of these phases accompanied by a general overview of major experimental results. Using the Ginzburg-Landau free energy appropriate to the system, we first discuss in detail the character and stability of the usual helical phase of cholesterics, showing that for certain parameter ranges the helical phase is unstable to the appearance of one or more blue phases. The two principal models for the blue phases are two limiting cases of the Ginzburg-Landau theory. We explore each limit and conclude with some general considerations of defects in both models and an exact minimization of the free energy in a curved three-dimensional space.
Berry phase in entangled systems
International Nuclear Information System (INIS)
Bertlmann, R.A.; Hasegawa, Y.; Hiesmayr, B.C.; Durstberger, C.
2005-01-01
Full text: The influence of the geometric phase, in particular the Berry phase, on an entangled spin-1/2 system is studied. We discuss in detail the case, where the geometric phase is generated only by one part of the Hilbert space. We are able to cancel the effects of the dynamical phase by using the 'spin-echo' method. We analyze how the Berry phase affects the Bell angles and the maximal violation of a CHSH-Bell inequality. Furthermore, we suggest an experimental realization of our setup within neutron interferometry. It is possible to create entanglement between different degrees of freedom (spin and spatial degree of freedom) for a single neutron. The influence of the geometrical phase on the entangled neutron state is tested experimentally which is work in progress. (author)
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-11-01
Knud E. Hansen A/S (KEH) has, partly funded by the Energy Research Programme, (EFP-95) investigated in the possibilities of using windships for transportation of cargo on long routes, i.e. across the Atlantic or Pacific Ocean. The task was to peruse experiences from projects made during the past 30 years and then, based on new materials and design principle to make proposals to modern wind driven ships to transportation of cargo - especially bulk carriers. KEH has thus prepared a suggestion for a 50,000 DWT wind driven bulk carrier on these terms. The bulk carrier in question is a modern rig inspired by the classical lugger and junk sail with a total sail area of abt. 10,000 m{sup 2}. The hull of the ship has been developed in order to limit wave resistance and drifting. Project Windship has, in contrast to earlier tests and projects, designed a bulk carrier based on a complete evaluation of ecology, safety, economy and reasonable transportation speed. The research project shows that international sea transportation, with wind as the primary source of energy, does not seem to run up against any obstacles as regards safety. The economical analyses show that windship transportation, with today`s oil prices, will be about 10% higher compared to the diesel driven transportation. In the light of the positive results of the research project the steering committee recommends that phase II of project `Modern Windships` is carried out. (EG)
International Nuclear Information System (INIS)
1996-11-01
Knud E. Hansen A/S (KEH) has, partly funded by the Energy Research Programme, (EFP-95) investigated in the possibilities of using windships for transportation of cargo on long routes, i.e. across the Atlantic or Pacific Ocean. The task was to peruse experiences from projects made during the past 30 years and then, based on new materials and design principle to make proposals to modern wind driven ships to transportation of cargo - especially bulk carriers. KEH has thus prepared a suggestion for a 50,000 DWT wind driven bulk carrier on these terms. The bulk carrier in question is a modern rig inspired by the classical lugger and junk sail with a total sail area of abt. 10,000 m 2 . The hull of the ship has been developed in order to limit wave resistance and drifting. Project Windship has, in contrast to earlier tests and projects, designed a bulk carrier based on a complete evaluation of ecology, safety, economy and reasonable transportation speed. The research project shows that international sea transportation, with wind as the primary source of energy, does not seem to run up against any obstacles as regards safety. The economical analyses show that windship transportation, with today's oil prices, will be about 10% higher compared to the diesel driven transportation. In the light of the positive results of the research project the steering committee recommends that phase II of project 'Modern Windships' is carried out. (EG)
Phase change materials handbook
Hale, D. V.; Hoover, M. J.; Oneill, M. J.
1971-01-01
This handbook is intended to provide theory and data needed by the thermal design engineer to bridge the gap between research achievements and actual flight systems, within the limits of the current state of the art of phase change materials (PCM) technology. The relationship between PCM and more conventional thermal control techniques is described and numerous space and terrestrial applications of PCM are discussed. Material properties of the most promising PCMs are provided; the purposes and use of metallic filler materials in PCM composites are presented; and material compatibility considerations relevant to PCM design are included. The engineering considerations of PCM design are described, especially those pertaining to the thermodynamic and heat transfer phenomena peculiar to PCM design. Methods of obtaining data not currently available are presented. The special problems encountered in the space environment are described. Computational tools useful to the designer are discussed. In summary, each aspect of the PCM problem important to the design engineer is covered to the extent allowed by the scope of this effort and the state of the art.
Kinetics of phase transformations
International Nuclear Information System (INIS)
Thompson, M.O.; Aziz, M.J.; Stephenson, G.B.
1992-01-01
This volume contains papers presented at the Materials Research Society symposium on Kinetics of Phase Transformations held in Boston, Massachusetts from November 26-29, 1990. The symposium provided a forum for research results in an exceptionally broad and interdisciplinary field. Presentations covered nearly every major class of transformations including solid-solid, liquid-solid, transport phenomena and kinetics modeling. Papers involving amorphous Si, a dominant topic at the symposium, are collected in the first section followed by sections on four major areas of transformation kinetics. The symposium opened with joint sessions on ion and electron beam induced transformations in conjunction with the Surface Chemistry and Beam-Solid Interactions: symposium. Subsequent sessions focused on the areas of ordering and nonlinear diffusion kinetics, solid state reactions and amorphization, kinetics and defects of amorphous silicon, and kinetics of melting and solidification. Seven internationally recognized invited speakers reviewed many of the important problems and recent results in these areas, including defects in amorphous Si, crystal to glass transformations, ordering kinetics, solid-state amorphization, computer modeling, and liquid/solid transformations
Fisher, J. Richard; Bradley, Richard F.; Brisken, Walter F.; Cotton, William D.; Emerson, Darrel T.; Kerr, Anthony R.; Lacasse, Richard J.; Morgan, Matthew A.; Napier, Peter J.; Norrod, Roger D.; Payne, John M.; Pospieszalski, Marian W.; Symmes, Arthur; Thompson, A. Richard; Webber, John C.
2009-03-01
This white paper offers cautionary observations about the planning and development of new, large radio astronomy instruments. Complexity is a strong cost driver so every effort should be made to assign differing science requirements to different instruments and probably different sites. The appeal of shared resources is generally not realized in practice and can often be counterproductive. Instrument optimization is much more difficult with longer lists of requirements, and the development process is longer and less efficient. More complex instruments are necessarily further behind the technology state of the art because of longer development times. Including technology R&D in the construction phase of projects is a growing trend that leads to higher risks, cost overruns, schedule delays, and project de-scoping. There are no technology breakthroughs just over the horizon that will suddenly bring down the cost of collecting area. Advances come largely through careful attention to detail in the adoption of new technology provided by industry and the commercial market. Radio astronomy instrumentation has a very bright future, but a vigorous long-term R&D program not tied directly to specific projects needs to be restored, fostered, and preserved.
Membrane fusion and inverted phases
International Nuclear Information System (INIS)
Ellens, H.; Siegel, D.P.; Alford, D.; Yeagle, P.L.; Boni, L.; Lis, L.J.; Quinn, P.J.; Bentz, J.
1989-01-01
We have found a correlation between liposome fusion kinetics and lipid phase behavior for several inverted phase forming lipids. N-Methylated dioleoylphosphatidylethanolamine (DOPE-Me), or mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), will form an inverted hexagonal phase (HII) at high temperatures (above TH), a lamellar phase (L alpha) at low temperatures, and an isotropic/inverted cubic phase at intermediate temperatures, which is defined by the appearance of narrow isotropic 31 P NMR resonances. The phase behavior has been verified by using high-sensitivity DSC, 31 P NMR, freeze-fracture electron microscopy, and X-ray diffraction. The temperature range over which the narrow isotropic resonances occur is defined as delta TI, and the range ends at TH. Extruded liposomes (approximately 0.2 microns in diameter) composed of these lipids show fusion and leakage kinetics which are strongly correlated with the temperatures of these phase transitions. At temperatures below delta TI, where the lipid phase is L alpha, there is little or no fusion, i.e., mixing of aqueous contents, or leakage. However, as the temperature reaches delta TI, there is a rapid increase in both fusion and leakage rates. At temperatures above TH, the liposomes show aggregation-dependent lysis, as the rapid formation of HII phase precursors disrupts the membranes. We show that the correspondence between the fusion and leakage kinetics and the observed phase behavior is easily rationalized in terms of a recent kinetic theory of L alpha/inverted phase transitions. In particular, it is likely that membrane fusion and the L alpha/inverted cubic phase transition proceed via a common set of intermembrane intermediates
Phase detection electronics for CLIC
Andersson, A
2011-01-01
The Compact Linear Collider (CLIC) requires very tight RF phase synchronisation in order to preserve high luminosity. The electronics required for processing the signals delivered from the phase pick-ups present a significant challenge. This paper discusses the strategy adopted to achieve a sufficiently accurate measurement of the phase. Performance measurements performed in the lab of some of the sub-systems are also presented.
Hybrid Nanocomposite Photovoltaics, Phase I
National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will develop an innovative solar cell design that combines nanotechnology with conducting polymer...
Quantum computers in phase space
International Nuclear Information System (INIS)
Miquel, Cesar; Paz, Juan Pablo; Saraceno, Marcos
2002-01-01
We represent both the states and the evolution of a quantum computer in phase space using the discrete Wigner function. We study properties of the phase space representation of quantum algorithms: apart from analyzing important examples, such as the Fourier transform and Grover's search, we examine the conditions for the existence of a direct correspondence between quantum and classical evolutions in phase space. Finally, we describe how to measure directly the Wigner function in a given phase-space point by means of a tomographic method that, itself, can be interpreted as a simple quantum algorithm
Qubit rotation and Berry phase
International Nuclear Information System (INIS)
Banerjee, D.; Bandyopadhyay, P.
2005-11-01
A quantized fermion is represented by a scalar particle encircling a magnetic flux line. It has the spinor structure which can be constructed from quantum gates and qubits. We have studied here the role of Berry phase in removing dynamical phase during one qubit rotation of a quantized fermion. The entanglement of two qubits inserting spin-echo to one of them results the trapped Berry phase to measure entanglement. Some effort is given to study the effect of noise on the Berry phase of spinors and their entangled states. (author)
Magnetic resonance of phase transitions
Owens, Frank J; Farach, Horacio A
1979-01-01
Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also
Three phase spiral liver Scanning
International Nuclear Information System (INIS)
Kanyanja, T.A.
2006-01-01
The ability to perform rapid back-to-back spiral acquisitions is an important recent technical advantage of spiral CT. this allows imaging of the upper abdomen (liver) during peak arterial enhancement (arterial phase) and during peak hepatic parenchymal enhancement (portal venous phase). Breatheld spiral CT has completely replaced dynamic incremental CT for evaluation of the liver. in selected patients with hyper vascular metastasis (hepatoma, neuroendocrine tumors, renal cell carcinoma, etc.) a biphasic examination is performed with one spiral acquisition obtained during the hepatic arterial phase and a second acquisition during the portal venous phase
Geometric phase from dielectric matrix
International Nuclear Information System (INIS)
Banerjee, D.
2005-10-01
The dielectric property of the anisotropic optical medium is found by considering the polarized photon as two component spinor of spherical harmonics. The Geometric Phase of a polarized photon has been evaluated in two ways: the phase two-form of the dielectric matrix through a twist and the Pancharatnam phase (GP) by changing the angular momentum of the incident polarized photon over a closed triangular path on the extended Poincare sphere. The helicity in connection with the spin angular momentum of the chiral photon plays the key role in developing these phase holonomies. (author)
Electronically soft phases in manganites.
Milward, G C; Calderón, M J; Littlewood, P B
2005-02-10
The phenomenon of colossal magnetoresistance in manganites is generally agreed to be a result of competition between crystal phases with different electronic, magnetic and structural order; a competition which can be strong enough to cause phase separation between metallic ferromagnetic and insulating charge-modulated states. Nevertheless, closer inspection of phase diagrams in many manganites reveals complex phases where the two order parameters of magnetism and charge modulation unexpectedly coexist. Here we show that such experiments can be naturally explained within a phenomenological Ginzburg-Landau theory. In contrast to models where phase separation originates from disorder or as a strain-induced kinetic phenomenon, we argue that magnetic and charge modulation coexist in new thermodynamic phases. This leads to a rich diagram of equilibrium phases, qualitatively similar to those seen experimentally. The success of this model argues for a fundamental reinterpretation of the nature of charge modulation in these materials, from a localized to a more extended 'charge-density wave' picture. The same symmetry considerations that favour textured coexistence of charge and magnetic order may apply to many electronic systems with competing phases. The resulting 'electronically soft' phases of matter with incommensurate, inhomogeneous and mixed order may be general phenomena in correlated systems.
Qubit rotation and Berry phase
International Nuclear Information System (INIS)
Banerjee, Dipti; Bandyopadhyay, Pratul
2006-01-01
A quantized fermion is represented by a scalar particle encircling a magnetic flux line. It has a spinor structure which can be constructed from quantum gates and qubits. We have studied here the role of Berry phase in removing dynamical phase during one qubit rotation of a quantized fermion. The entanglement of two qubits inserting spin-echo to one of them allows the trapped Berry phase to measure entanglement. Some effort is given to study the effect of noise on the Berry phase of spinors and their entangled states
Savanna ecosystem project: phase I summary and phase II progress
CSIR Research Space (South Africa)
Huntely, BJ
1978-07-01
Full Text Available A summary of the results of the first phase (mid 1974 to mid 1976) of the South African Savanna Ecosystem Project being undertaken at Nylsvley in the northern Transvaal is presented. Phase I of this ten year study of the structure and functioning...
High pressure phases of terbium: Possibility of a thcp phase
International Nuclear Information System (INIS)
Staun Olsen, J.; Steenstrup, S.; Gerward, L.
1985-01-01
High pressure phases of trivalent Tb studied by energy dispersive X-ray diffraction with synchrotron radiation exhibits the closed packed sequence (hcp -> Sm -> dhcp -> fcc) typical of the trivalent rare earth metals. Furthermore, a phase consistent with a triple hexagonal closed packed (thcp) structure was observed in a narrow pressure range around 30 GPa. (orig.)
Environmental program. Phase 2
International Nuclear Information System (INIS)
1993-03-01
The Norwegian Oil Industry Association (OLF) has between 1991 and 1993 conducted an environmental program. The objectives were to: Enhance the knowledge of emissions to air and discharges to sea from Norwegian offshore oil and gas production operations. Evaluate the technology and the associated costs for potential reduction of continuous emissions and discharges. Phase 2 of the program has in particular focused on the relationship between the cost and benefit of emission and discharge reduction measures. The purpose has been to identify the measures giving the largest reductions per unit cost. This has now been performed and is documented in 24 technical reports. Total production of oil and gas from the Norwegian sector was 130 million tons oil equivalents (toe) in 1992, most of which was exported to markets in Europe. All this will ultimately be consumed, primarily through energy conversion processes, with release of CO 2 and other greenhouse emission gases. The current gas production of 26 million toe per year will increase rapidly during the coming ten years, while the present increase in oil production is expected to culminate in the same period. Reduction of atmospheric emissions from the Norwegian oil and gas industry may be achieved primarily through energy efficiency measures. Approximately 2.5% of the fossil fuel energy is consumed in the production and transportation process. Different environmental standards between producing nations will primarily affect production cost. The competitiveness of the various producing regions, rather than the overall environmental impact of the petroleum industry and its products, will be effected. 36 refs., 61 figs., 33 tabs
Phase transitions in surfactant monolayers
International Nuclear Information System (INIS)
Casson, B.D.
1998-01-01
Two-dimensional phase transitions have been studied in surfactant monolayers at the air/water interface by sum-frequency spectroscopy and ellipsometry. In equilibrium monolayers of medium-chain alcohols C n H 2n+1 OH (n = 9-14) a transition from a two-dimensional crystalline phase to a liquid was observed at temperatures above the bulk melting point. The small population of gauche defects in the solid phase increased only slightly at the phase transition. A model of the hydrocarbon chains as freely rotating rigid rods allowed the area per molecule and chain tilt in the liquid phase to be determined. The area per molecule, chain tilt and density of the liquid phase all increased with increasing chain length, but for each chain length the density was higher than in a bulk liquid hydrocarbon. In a monolayer of decanol adsorbed at the air/water interface a transition from a two-dimensional liquid to a gas was observed. A clear discontinuity in the coefficient of ellipticity as a function of temperature showed that the transition is first-order. This result suggests that liquid-gas phase transitions in surfactant monolayers may be more widespread than once thought. A solid-liquid phase transition has also been studied in mixed monolayers of dodecanol with an anionic surfactant (sodium dodecyl sulphate) and with a homologous series of cationic surfactants (alkyltrimethylammonium bromides: C n TABs, n = 12, 14, 16). The composition and structure of the mixed monolayers was studied above and below the phase transition. At low temperatures the mixed monolayers were as densely packed as a monolayer of pure dodecanol in its solid phase. At a fixed temperature the monolayers under-went a first-order phase transition to form a phase that was less dense and more conformationally disordered. The proportion of ionic surfactant in the mixed monolayer was greatest in the high temperature phase. As the chain length of the C n TAB increased the number of conformational defects
78 FR 33911 - Phased Retirement
2013-06-05
... to implement phased retirement, a new human resources tool that allows full-time employees to work a..., 582, 831, et al. Phased Retirement; Proposed Rule #0;#0;Federal Register / Vol. 78 , No. 108 / Wednesday, June 5, 2013 / Proposed Rules#0;#0; [[Page 33912
Generalized definitions of phase transitions
International Nuclear Information System (INIS)
Chomaz, Ph.; Gulminelli, F.
2001-09-01
We define a first order phase transition as a bimodality of the event distribution in the space of observations and we show that this is equivalent to a curvature anomaly of the thermodynamical potential and that it implies the Yang Lee behavior of the zeros of the partition sum. Moreover, it allows to study phase transitions out of equilibrium. (authors)
Beam phase space and emittance
International Nuclear Information System (INIS)
Buon, J.
1990-12-01
The classical and elementary results for canonical phase space, the Liouville theorem and the beam emittance are reviewed. Then, the importance of phase portraits to obtain a geometrical description of motion is emphasized, with examples in accelerator physics. Finally, a statistical point of view is used to define beam emittance, to study its law of approximate conservation and to treat two particular examples
Multiphase flows with phase change
Indian Academy of Sciences (India)
Multiphase flows with phase change are ubiquitous in many industrial sectors ranging from energy and infra-structure to specialty chemicals and pharmaceuticals. My own interest in mul- tiphase flows with phase change started more than 15 years ago when I had initiated work on riser reactor for fluid catalytic cracking and ...
Phase transitions in field theory
International Nuclear Information System (INIS)
Carvalho, C.A.A. de; Bollini, C.G.; Giambiagi, J.J.
1984-01-01
By means of an example for which the effective potential is explicitly calculable (up to the one loop approximation), it is discussed how a phase transition takes place as the temperature is increased and pass from spontaneously broken symmetry to a phase in which the symmetry is restored. (Author) [pt
Moment Distributions of Phase Type
DEFF Research Database (Denmark)
Bladt, Mogens; Nielsen, Bo Friis
2011-01-01
Moment distributions of phase-type and matrix-exponential distributions are shown to remain within their respective classes. We provide a probabilistic phase-type representation for the former case and an alternative representation, with an analytically appealing form, for the latter. First order...
Graphene based terahertz phase modulators
Kakenov, N.; Ergoktas, M. S.; Balci, O.; Kocabas, C.
2018-07-01
Electrical control of amplitude and phase of terahertz radiation (THz) is the key technological challenge for high resolution and noninvasive THz imaging. The lack of active materials and devices hinders the realization of these imaging systems. Here, we demonstrate an efficient terahertz phase and amplitude modulation using electrically tunable graphene devices. Our device structure consists of electrolyte-gated graphene placed at quarter wavelength distance from a reflecting metallic surface. In this geometry, graphene operates as a tunable impedance surface which yields electrically controlled reflection phase. Terahertz time domain reflection spectroscopy reveals the voltage controlled phase modulation of π and the reflection modulation of 50 dB. To show the promises of our approach, we demonstrate a multipixel phase modulator array which operates as a gradient impedance surface.
Nanoscale phase change memory materials.
Caldwell, Marissa A; Jeyasingh, Rakesh Gnana David; Wong, H-S Philip; Milliron, Delia J
2012-08-07
Phase change memory materials store information through their reversible transitions between crystalline and amorphous states. For typical metal chalcogenide compounds, their phase transition properties directly impact critical memory characteristics and the manipulation of these is a major focus in the field. Here, we discuss recent work that explores the tuning of such properties by scaling the materials to nanoscale dimensions, including fabrication and synthetic strategies used to produce nanoscale phase change memory materials. The trends that emerge are relevant to understanding how such memory technologies will function as they scale to ever smaller dimensions and also suggest new approaches to designing materials for phase change applications. Finally, the challenges and opportunities raised by integrating nanoscale phase change materials into switching devices are discussed.
Phase-sensitive flow cytometer
Energy Technology Data Exchange (ETDEWEB)
Steinkamp, J.A.
1992-12-31
This report describes phase-sensitive flow cytometer (FCM) which provides additional FCM capability to use the fluorescence lifetime of one or more fluorochromes bound to single cells to provide additional information regarding the cells. The resulting fluorescence emission can be resolved into individual fluorescence signals if two fluorochromes are present or can be converted directly to a decay lifetime from a single fluorochrome. The excitation light for the fluorochromes is modulated to produce an amplitude modulated fluorescence pulse as the fluorochrome is excited in the FCM. The modulation signal also forms a reference signal that is phase-shifted a selected amount for subsequent mixing with the output modulated fluorescence intensity signal in phase-sensitive detection circuitry. The output from the phase-sensitive circuitry is then an individual resolved fluorochrome signal or a single fluorochrome decay lifetime, depending on the applied phase shifts.
Phase transition in finite systems
International Nuclear Information System (INIS)
Chomaz, Ph.; Duflot, V.; Duflot, V.; Gulminelli, F.
2000-01-01
In this paper we present a review of selected aspects of Phase transitions in finite systems applied in particular to the liquid-gas phase transition in nuclei. We show that the problem of the non existence of boundary conditions can be solved by introducing a statistical ensemble with an averaged constrained volume. In such an ensemble the microcanonical heat capacity becomes negative in the transition region. We show that the caloric curve explicitly depends on the considered transformation of the volume with the excitation energy and so does not bear direct informations on the characteristics of the phase transition. Conversely, partial energy fluctuations are demonstrated to be a direct measure of the equation of state. Since the heat capacity has a negative branch in the phase transition region, the presence of abnormally large kinetic energy fluctuations is a signal of the liquid gas phase transition. (author)
129I Interlaboratory comparison: phase I and phase II
International Nuclear Information System (INIS)
Caffee, M. W.; Roberts, M. L.
1999-01-01
An interlaboratory comparison exercise for 129 I was organized and conducted. Nine laboratories participated in the exercise to either a full or limited extent. In Phase I of the comparison, 11 samples were measured. The suite of samples contained both synthetic ''standard type'' materials (i.e., AgI) and environmental materials. The isotopic 129 I/ 127 I ratios of the samples varied from 10 -8 to 10 -14 . In this phase, each laboratory was responsible for its own chemical preparation of the samples. In Phase I, the 129 I AMS measurements for prepared AgI were in good agreement. However, large discrepancies were seen in 129 I AMS measurements of environmental samples. Because of the large discrepancies seen in the Phase I 129 I intercomparison, a subsequent study was conducted. In Phase II of the 129 I intercomparison, three separate laboratories prepared AgI from two environmental samples (IAEA 375 soil and maples leaves). Each laboratory used its own chemical preparation method with each of the methods being distinctly different. The resulting six samples (two sets of three) were then re-distributed to the participating 129 I AMS facilities and 129 I/ 127 I ratios measured. Results and discussion of both the Phase I and Phase II interlaboratory comparison are presented
Phase conversion for fusion lasers
International Nuclear Information System (INIS)
Kessler, T.; Castle, W.; Sampat, N.; Skupsky, S.; Smith, D.; Swales, S.
1988-01-01
An essential requirement for direct drive laser fusion is the uniform irradiation of spherical targets that are located in the quasi-far field of a laser system. A major impediment to irradiation uniformity with high-power solid-state laser systems is the presence of a hot-spot structure at the target plane. The hot-spot intensity nonuniformities are caused by spatial variations in the near-field phase front of each laser beam. Although for many tabletop applications diffraction-limited laser performance can be obtained through static phase correction, adaptive optics, or phase conjugation, such approaches are either excessively expensive, difficult to implement, or not yet available for large-aperture, high-peak-power laser beams. An alternative to phase correcting a wavefront involves modifying the laser beam's coherence properties thereby changing its focusing characteristics. The method of induced spatial incoherence (ISI) involves a reduction in both spatial and temporal coherence. Other methods are based on modifications of only the spatial coherence of a laser beam. A phase conversion technology which incorporates a distribution of near-field phases to either perform static phase correction or induce spatial incoherence offers a route toward increasingly higher levels of irradiation uniformity
Anisotropies of in-phase, out-of-phase,\
Czech Academy of Sciences Publication Activity Database
Hrouda, F.; Chadima, Martin; Ježek, J.; Kadlec, Jaroslav
2018-01-01
Roč. 62 (2018) ISSN 0039-3169 Institutional support: RVO:67985530 ; RVO:67985831 Keywords : anisotropy * out-of-phase susceptibility * frequency-dependent susceptibility Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.764, year: 2016
Flexible, Phase Change Fabric for Deployable Decelerators, Phase I
National Aeronautics and Space Administration — SDMA proposes to develop a flexible fabric containing Phase Change Materials that is suitable for use on Deployable Decelerators. This technology will make...
Gas hydrate phase equilibria measurement techniques and phase rule considerations
International Nuclear Information System (INIS)
Beltran, Juan G.; Bruusgaard, Hallvard; Servio, Phillip
2012-01-01
Highlights: → Inconsistencies found in hydrate literature. → Clarification to the number of variables needed to satisfy and justify equilibrium data. → Application of phase rule to mixed hydrate systems. → Thermodynamically consistent format to present data. - Abstract: A brief review of the Gibbs phase rule for non-reacting systems and its correct application to clathrate hydrates is presented. Clarification is provided for a common mistake found in hydrate phase-equilibria literature, whereby initial compositions are used as intensive variables to satisfy the Gibbs phase rule instead of the equilibrium values. The system of (methane + carbon dioxide + water) under (hydrate + liquid + vapor) equilibrium is used as a case study to illustrate key points and suggestions to improve experimental techniques are proposed.
An absorbing phase transition from a structured active particle phase
Energy Technology Data Exchange (ETDEWEB)
Lopez, Cristobal [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain); Ramos, Francisco [Departamento de Electromagnetismo y Fisica de la Materia and Instituto de Fisica Teorica y Computacional Carlos I, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain); Hernandez-GarcIa, Emilio [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain)
2007-02-14
In this work we study the absorbing state phase transition of a recently introduced model for interacting particles with neighbourhood-dependent reproduction rates. The novelty of the transition is that as soon as the active phase is reached by increasing a control parameter a periodically arranged structure of particle clusters appears. A numerical study in one and two dimensions shows that the system falls into the directed percolation universality class.
Phase behavior and phase inversion for dispersant systems
International Nuclear Information System (INIS)
Solheim, A.; Brandvik, P.J.
1991-06-01
This report describes some preliminary phase behavior studies and phase inversion temperature measurements in seawater, bunker oil and dispersant. The objectives have been to find new ways of characterizing dispersants for dispersing oil spill at sea and, perhaps, to throw new lights on the mechanism of dispersion formation (oil-in-water emulsification). The work has been focussed on the relation to phase behavior and the existence of microemulsion in equilibrium with excess oil and water phases. The dispersing process is also compared to the recommended conditions for emulsion formation. When forming an oil-in-water emulsion in an industrial process, it is recommended to choose an emulsifier which gives a phase inversion temperature (PIT) which is 20 - 60 o C higher than the actual temperature for use. The emulsification process must take place close to the PIT which is the temperature at which the emulsion change from oil-in-water emulsion to water-in-oil emulsion when the system is stirred. This condition corresponds to the temperature where the phase behavior change character. The purpose has been to find out if the composition of the dispersants corresponds to the recommendations for oil-in-water emulsification. The amount of experimental work has been limited. Two kinds of experiments have been carried out. Phase behavior studies have been done for seawater, bunker oil and four different dispersants where one had an optimal composition. The phase behavior was hard to interpret and is not recommended for standard dispersants test. The other experimental technique was PIT-measurements by conductivity measurements versus temperature. 4 figs., 1 tab., 4 refs
Phase Noise Tolerant QPSK Receiver Using Phase Sensitive Wavelength Conversion
DEFF Research Database (Denmark)
Da Ros, Francesco; Xu, Jing; Lei, Lei
2013-01-01
A novel QPSK receiver based on a phase noise reduction pre-stage exploiting PSA in a HNLF and balanced detection is presented. Receiver sensitivity improvement over a conventional balanced receiver is demonstrated.......A novel QPSK receiver based on a phase noise reduction pre-stage exploiting PSA in a HNLF and balanced detection is presented. Receiver sensitivity improvement over a conventional balanced receiver is demonstrated....
Quantum mechanics in phase space
DEFF Research Database (Denmark)
Hansen, Frank
1984-01-01
A reformulation of quantum mechanics for a finite system is given using twisted multiplication of functions on phase space and Tomita's theory of generalized Hilbert algebras. Quantization of a classical observable h is achieved when the twisted exponential Exp0(-h) is defined as a tempered....... Generalized Weyl-Wigner maps related to the notion of Hamiltonian weight are studied and used in the formulation of a twisted spectral theory for functions on phase space. Some inequalities for Wigner functions on phase space are proven. A brief discussion of the classical limit obtained through dilations...
Fundamentals of ultrasonic phased arrays
Schmerr, Lester W
2014-01-01
This book describes in detail the physical and mathematical foundations of ultrasonic phased array measurements.?The book uses linear systems theory to develop a comprehensive model of the signals and images that can be formed with phased arrays. Engineers working in the field of ultrasonic nondestructive evaluation (NDE) will find in this approach a wealth of information on how to design, optimize and interpret ultrasonic inspections with phased arrays. The fundamentals and models described in the book will also be of significant interest to other fields, including the medical ultrasound and
A Phase Matching, Adiabatic Accelerator
Energy Technology Data Exchange (ETDEWEB)
Lemery, Francois [Hamburg U.; Flöttmann, Klaus [DESY; Kärtner, Franz [CFEL, Hamburg; Piot, Philippe [Northern Illinois U.
2017-05-01
Tabletop accelerators are a thing of the future. Reducing their size will require scaling down electromagnetic wavelengths; however, without correspondingly high field gradients, particles will be more susceptible to phase-slippage – especially at low energy. We investigate how an adiabatically-tapered dielectric-lined waveguide could maintain phase-matching between the accelerating mode and electron bunch. We benchmark our simple model with CST and implement it into ASTRA; finally we provide a first glimpse into the beam dynamics in a phase-matching accelerator.
Covariant phase difference observables in quantum mechanics
International Nuclear Information System (INIS)
Heinonen, Teiko; Lahti, Pekka; Pellonpaeae, Juha-Pekka
2003-01-01
Covariant phase difference observables are determined in two different ways, by a direct computation and by a group theoretical method. A characterization of phase difference observables which can be expressed as the difference of two phase observables is given. The classical limits of such phase difference observables are determined and the Pegg-Barnett phase difference distribution is obtained from the phase difference representation. The relation of Ban's theory to the covariant phase theories is exhibited
Composite Repair System, Phase I
National Aeronautics and Space Administration — GTL has developed an innovative composite repair methodology known as the Composite Repair System (CRS). In this phase I effort, CRS is being developed for the...
Non-equilibrium phase transitions
Henkel, Malte; Lübeck, Sven
2009-01-01
This book describes two main classes of non-equilibrium phase-transitions: (a) static and dynamics of transitions into an absorbing state, and (b) dynamical scaling in far-from-equilibrium relaxation behaviour and ageing. The first volume begins with an introductory chapter which recalls the main concepts of phase-transitions, set for the convenience of the reader in an equilibrium context. The extension to non-equilibrium systems is made by using directed percolation as the main paradigm of absorbing phase transitions and in view of the richness of the known results an entire chapter is devoted to it, including a discussion of recent experimental results. Scaling theories and a large set of both numerical and analytical methods for the study of non-equilibrium phase transitions are thoroughly discussed. The techniques used for directed percolation are then extended to other universality classes and many important results on model parameters are provided for easy reference.
Vermont Center for Geographic Information — The stream geomorphic assessment (SGA) is a physical assessment competed by geomorphologists to determine the condition and sensitivity of a stream. The Phase 2 SGA...
Phase transition in finite systems
International Nuclear Information System (INIS)
Chomaz, Ph.; Duflot, V.; Duflot, V.; Gulminelli, F.
2000-01-01
The general problem of the definition of a phase transition without employing the thermodynamical limit is addressed. Different necessary conditions are considered and illustrated with examples from different nuclear and general physics phenomenologies. (authors)
Phase transitions and quantum entropy
International Nuclear Information System (INIS)
Arrachea, L.; Canosa, N.; Plastino, A.; Portesi, M.; Rossignoli, R.
1990-01-01
An examination is made of the possibility to predict phase transitions of the fundamental state of finite quantum system, knowing the quantum entropy of these states, defined on the basis of the information theory. (Author). 7 refs., 3 figs
CLIC Drive Beam Phase Stabilisation
Gerbershagen, Alexander; Schulte, Daniel
The thesis presents phase stability studies for the Compact Linear Collider (CLIC) and focuses in particular on CLIC Drive Beam longitudinal phase stabilisation. This topic constitutes one of the main feasibility challenges for CLIC construction and is an essential component of the current CLIC stabilisation campaign. The studies are divided into two large interrelated sections: the simulation studies for the CLIC Drive Beam stability, and measurements, data analysis and simulations of the CLIC Test Facility (CTF3) Drive Beam phase errors. A dedicated software tool has been developed for a step-by-step analysis of the error propagation through the CLIC Drive Beam. It uses realistic RF potential and beam loading amplitude functions for the Drive and Main Beam accelerating structures, complete models of the recombination scheme and compressor chicane as well as of further CLIC Drive Beam modules. The tool has been tested extensively and its functionality has been verified. The phase error propagation at CLIC h...
Phase transition in finite systems
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph.; Duflot, V. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France); Duflot, V.; Gulminelli, F. [Laboratoire de Physique Corpusculaire, LPC-ISMRa, CNRS-IN2P3, 14 - Caen (France)
2000-07-01
The general problem of the definition of a phase transition without employing the thermodynamical limit is addressed. Different necessary conditions are considered and illustrated with examples from different nuclear and general physics phenomenologies. (authors)
Berry's Phase and Fine Structure
Binder, B
2002-01-01
Irrational numbers can be assigned to physical entities based on iterative processes of geometric objects. It is likely that iterative round trips of vector signals include a geometric phase component. If so, this component will couple back to the round trip frequency or path length generating an non-linear feedback loop (i.e. induced by precession). In this paper such a quantum feedback mechanism is defined including generalized fine structure constants in accordance with the fundamental gravitomagnetic relation of spin-orbit coupling. Supported by measurements, the general relativistic and topological background allows to propose, that the deviation of the fine structure constant from 1/137 could be assigned to Berry's phase. The interpretation is straightforward: spacetime curvature effects can be greatly amplified by non-linear phase-locked feedback-loops adjusted to single-valued phase relationships in the quantum regime.
Inequalities for scattering phase shifts
International Nuclear Information System (INIS)
Baumgartner, B.; Grosse, H.
1985-01-01
A recently developed method, which was used to derive bounds on energy levels, is applied to continuous spectra and gives relations between scattering phase shifts of various angular momenta. (Author)
Berry phase in Heisenberg representation
Andreev, V. A.; Klimov, Andrei B.; Lerner, Peter B.
1994-01-01
We define the Berry phase for the Heisenberg operators. This definition is motivated by the calculation of the phase shifts by different techniques. These techniques are: the solution of the Heisenberg equations of motion, the solution of the Schrodinger equation in coherent-state representation, and the direct computation of the evolution operator. Our definition of the Berry phase in the Heisenberg representation is consistent with the underlying supersymmetry of the model in the following sense. The structural blocks of the Hamiltonians of supersymmetrical quantum mechanics ('superpairs') are connected by transformations which conserve the similarity in structure of the energy levels of superpairs. These transformations include transformation of phase of the creation-annihilation operators, which are generated by adiabatic cyclic evolution of the parameters of the system.
Sustainable Water Purification, Phase I
National Aeronautics and Space Administration — Newly developed phase-engineered and low dimensional materials have opened the door to the design of materials structures that exhibit extremely efficient ionic...
Phase holograms in polymethyl methacrylate
Maker, P. D.; Muller, R. E.
1992-01-01
A procedure is described for the fabrication of complex computer-generated phase holograms in polymethyl methacrylate (PMMA) by means of partial-exposure e-beam lithography and subsequent carefully controlled partial development. Following the development, the pattern appears (rendered in relief) in the PMMA, which then acts as the phase-delay medium. The devices fabricated were designed with 16 equal phase steps per retardation cycle, were up to 3 mm square, and consisted of up to 10 millions of 0.3-2.0-micron square pixels. Data files were up to 60 Mb-long, and the exposure times ranged to several hours. A Fresnel phase lens was fabricated with a diffraction-limited optical performance of 83-percent efficiency.
High Performance Nanolauncher, Phase I
National Aeronautics and Space Administration — The proposed Low Cost Nanolauncher (LCN) is an upper stage using a new, inexpensive propulsion system. The Phase I program will combine several technologies with a...
Vermont Center for Geographic Information — The stream geomorphic assessment (SGA) is a physical assessment competed by geomorphologists to determine the condition and sensitivity of a stream. The Phase 1 SGA...
Modern theories of phase transitions
International Nuclear Information System (INIS)
Rajaraman, R.
1979-01-01
Modern applications of the ideas of phase transitions to nuclear systems and the modern techniques as applied to familiar phase transitions in solid-state physics are discussed with illustrations. The phenomenon of pion condensation in nuclei and neutron stars, is presented as an example of phase transitions in nuclear systems. The central physical ideas behind this subject as well as techniques used to tackle it are broadly summarised. It is pointed out that unlike familiar examples of ferromagnetism or superconductivity, the order parameter here has spatial variation even in the ground state. Possible experimental consequences are discussed. As an example of the second category, the use of renormalisation group techniques in solid state physics is reviewed. The basic idea behind the renormalisation group in the infra-red (thermodynamic) limit is presented. The observed universality and scaling of critical exponents in second order phase transitions is explained in a model-independent way. (auth.)
International Nuclear Information System (INIS)
Balonis, M.; Glasser, F.P.
2009-01-01
The densities of principal crystalline phases occurring in Portland cement are critically assessed and tabulated, in some cases with addition of new data. A reliable and self-consistent density set for crystalline phases was obtained by calculating densities from crystallographic data and unit cell contents. Independent laboratory work was undertaken to synthesize major AFm and AFt cement phases, determine their unit cell parameters and compare the results with those recorded in the literature. Parameters were refined from powder diffraction patterns using CELREF 2 software. A density value is presented for each phase, showing literature sources, in some cases describing limitations on the data, and the weighting attached to numerical values where an averaging process was used for accepted data. A brief discussion is made of the consequences of the packing of water to density changes in AFm and AFt structures.
International Nuclear Information System (INIS)
Aoki, Ken-ichi
1988-01-01
Existence of a strong coupling phase in QED has been suggested in solutions of the Schwinger-Dyson equation and in Monte Carlo simulation of lattice QED. In this article we recapitulate the previous arguments, and formulate the problem in the modern framework of the renormalization theory, Wilsonian renormalization. This scheme of renormalization gives the best understanding of the basic structure of a field theory especially when it has a multi-phase structure. We resolve some misleading arguments in the previous literature. Then we set up a strategy to attack the strong phase, if any. We describe a trial; a coupled Schwinger-Dyson equation. Possible picture of the strong coupling phase QED is presented. (author)
Licensee Performance Evaluation: Phase II
International Nuclear Information System (INIS)
Chakoff, H.E.; Speaker, D.M.; Thompson, S.R.; Cohen, S.C.
1979-08-01
This report details work performed during the second phase of a two-phase contract to develop methodology for Licensee Performance Evaluation. The Phase I report, NUREG/CR-0110 details initial efforts on the contract. The model developed in Phase I was used to evaluate nine additional facilities for this report. Performance indicators from noncompliance data were also evaluated. Methodology was developed employing the noncompliance indicators and used for 12 case studies. It was found that licensee event report indicators could be more easily identified and utilized than noncompliance indicators based on presently available data systems. However, noncompliance data, appropriately related to cause, could provide real insight into why performance was what it was
Phase Coexistence in Insect Swarms
Sinhuber, Michael; Ouellette, Nicholas T.
2017-10-01
Animal aggregations are visually striking, and as such are popular examples of collective behavior in the natural world. Quantitatively demonstrating the collective nature of such groups, however, remains surprisingly difficult. Inspired by thermodynamics, we applied topological data analysis to laboratory insect swarms and found evidence for emergent, material-like states. We show that the swarms consist of a core "condensed" phase surrounded by a dilute "vapor" phase. These two phases coexist in equilibrium, and maintain their distinct macroscopic properties even though individual insects pass freely between them. We further define a pressure and chemical potential to describe these phases, extending theories of active matter to aggregations of macroscopic animals and laying the groundwork for a thermodynamic description of collective animal groups.
Phasing multi-segment undulators
International Nuclear Information System (INIS)
Chavanne, J.; Elleaume, P.; Vaerenbergh, P. Van
1996-01-01
An important issue in the manufacture of multi-segment undulators as a source of synchrotron radiation or as a free-electron laser (FEL) is the phasing between successive segments. The state of the art is briefly reviewed, after which a novel pure permanent magnet phasing section that is passive and does not require any current is presented. The phasing section allows the introduction of a 6 mm longitudinal gap between each segment, resulting in complete mechanical independence and reduced magnetic interaction between segments. The tolerance of the longitudinal positioning of one segment with respect to the next is found to be 2.8 times lower than that of conventional phasing. The spectrum at all gaps and useful harmonics is almost unchanged when compared with a single-segment undulator of the same total length. (au) 3 refs
Lunar Health Monitor, Phase II
National Aeronautics and Space Administration — During the Phase II Lunar Health Monitor program, Orbital Research will develop a second generation wearable sensor suite for astronaut physiologic monitoring. The...
High pressure phase transformations revisited.
Levitas, Valery I
2018-04-25
High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The main reason for the above mentioned discrepancy is the lack of understanding that there is a fundamental difference between pressure-induced transformations under hydrostatic conditions, stress-induced transformations under nonhydrostatic conditions below yield, and strain-induced transformations during plastic flow. Each of these types of transformations has different mechanisms and requires a completely different thermodynamic and kinetic description and experimental characterization. In comparison with other fields the following challenges are indicated for high pressure phase transformation: (a) initial and evolving microstructure is not included in characterization of transformations; (b) continuum theory is poorly developed; (c) heterogeneous stress and strain fields in experiments are not determined, which leads to confusing material transformational properties with a system behavior. Some ways to advance the field of high pressure phase transformations are suggested. The key points are: (a) to take into account plastic deformations and microstructure evolution during transformations; (b) to formulate phase transformation criteria and kinetic equations in terms of stress and plastic strain tensors (instead of pressure alone); (c) to develop multiscale continuum
High pressure phase transformations revisited
Levitas, Valery I.
2018-04-01
High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The main reason for the above mentioned discrepancy is the lack of understanding that there is a fundamental difference between pressure-induced transformations under hydrostatic conditions, stress-induced transformations under nonhydrostatic conditions below yield, and strain-induced transformations during plastic flow. Each of these types of transformations has different mechanisms and requires a completely different thermodynamic and kinetic description and experimental characterization. In comparison with other fields the following challenges are indicated for high pressure phase transformation: (a) initial and evolving microstructure is not included in characterization of transformations; (b) continuum theory is poorly developed; (c) heterogeneous stress and strain fields in experiments are not determined, which leads to confusing material transformational properties with a system behavior. Some ways to advance the field of high pressure phase transformations are suggested. The key points are: (a) to take into account plastic deformations and microstructure evolution during transformations; (b) to formulate phase transformation criteria and kinetic equations in terms of stress and plastic strain tensors (instead of pressure alone); (c) to develop multiscale continuum
Novel Quantum Phases at Interfaces
2014-12-12
defined quasiparticle and the system cannot be adequately described by an electronic band structure. The chief theoretical challenges for the study of...electronic quasiparticle weight is proportional to the expectation value of the rotor field. The resulting theory typically has two dis- tinct stable phases...band structure is well defined, while in the strongly interacting phase the quasiparticle weight vanishes due to strong rotor fluc- tuations
Phase transitions in two dimensions
International Nuclear Information System (INIS)
Henderson, D.
1980-01-01
Although a two-dimensional solid with long-range translational order cannot existin the thermodynamic limit (N → ∞, V →∞, N/V finite) macroscopic samples of two-dimensional solids can exist. In this work, stability of the phase was determined by the usuar method of equating the pressure and chemical potential of the phases. (A.C.A.S.) [pt
Glare Spot Phase Doppler Anemometry
Hespel, Camille; Ren, Kuan Fang; Gréhan, Gérard; Onofri, Fabrice
2006-01-01
International audience; The Phase Doppler anemometry has been developed to measure simultaneously the velocity and the size of droplets. The measurement of the refractive index is also necessary since it depends on the temperature and the composition of the particle and its measurement permits both to increase the quality of the diameter measurement and to obtain information on the temperature and/or the composition of the droplets. In this paper, we introduce a Glare Spot Phase Doppler Anemo...
Schleich, Wolfgang P.
2001-04-01
Quantum Optics in Phase Space provides a concise introduction to the rapidly moving field of quantum optics from the point of view of phase space. Modern in style and didactically skillful, Quantum Optics in Phase Space prepares students for their own research by presenting detailed derivations, many illustrations and a large set of workable problems at the end of each chapter. Often, the theoretical treatments are accompanied by the corresponding experiments. An exhaustive list of references provides a guide to the literature. Quantum Optics in Phase Space also serves advanced researchers as a comprehensive reference book. Starting with an extensive review of the experiments that define quantum optics and a brief summary of the foundations of quantum mechanics the author Wolfgang P. Schleich illustrates the properties of quantum states with the help of the Wigner phase space distribution function. His description of waves ala WKB connects semi-classical phase space with the Berry phase. These semi-classical techniques provide deeper insight into the timely topics of wave packet dynamics, fractional revivals and the Talbot effect. Whereas the first half of the book deals with mechanical oscillators such as ions in a trap or atoms in a standing wave the second half addresses problems where the quantization of the radiation field is of importance. Such topics extensively discussed include optical interferometry, the atom-field interaction, quantum state preparation and measurement, entanglement, decoherence, the one-atom maser and atom optics in quantized light fields. Quantum Optics in Phase Space presents the subject of quantum optics as transparently as possible. Giving wide-ranging references, it enables students to study and solve problems with modern scientific literature. The result is a remarkably concise yet comprehensive and accessible text- and reference book - an inspiring source of information and insight for students, teachers and researchers alike.
Modulational instability of nematic phase
Indian Academy of Sciences (India)
2014-02-08
Feb 8, 2014 ... all phases show MI, but at the same time it has also been found that for antiferro- magnetic phase, MI depends on the relative .... with wave functions, time and spatial coordinates are measured in the units of. (¯h/2mωz)−3/2, ω−1 ... The manipulation of the resulting matrix gives eigenvalues. From the form of ...
Phase transitions in nuclear matter
International Nuclear Information System (INIS)
Glendenning, N.K.
1984-11-01
The rather general circumstances under which a phase transition in hadronic matter at finite temperature to an abnormal phase in which baryon effective masses become small and in which copious baryon-antibaryon pairs appear is emphasized. A preview is also given of a soliton model of dense matter, in which at a density of about seven times nuclear density, matter ceases to be a color insulator and becomes increasingly color conducting. 22 references
Describing phase coexistence in systems with small phases
International Nuclear Information System (INIS)
Lovett, R
2007-01-01
Clusters of atoms can be studied in molecular beams and by computer simulation; 'liquid drops' provide elementary models for atomic nuclei and for the critical nuclei of nucleation theory. These clusters are often described in thermodynamic terms, but the behaviour of small clusters near a phase boundary is qualitatively different from the behaviour at a first order phase transition in idealized thermodynamics. In the idealized case the density and entropy show mathematically sharp discontinuities when the phase boundary is crossed. In large, but finite, systems, the phase boundaries become regions of state space wherein these properties vary rapidly but continuously. In small clusters with a large surface/volume ratio, however, the positive interfacial free energy makes it unlikely, even in states on phase boundaries, that a cluster will have a heterogeneous structure. What is actually seen in these states is a structure that fluctuates in time between homogeneous structures characteristic of the two sides of the phase boundary. That is, structural fluctuations are observed. Thermodynamics only predicts average properties; statistical mechanics is required to understand these fluctuations. Failure to distinguish thermodynamic properties and characterizations of fluctuations, particularly in the context of first order phase transitions, has led to suggestions that the classical rules for thermodynamic stability are violated in small systems and that classical thermodynamics provides an inconsistent description of these systems. Much of the confusion stems from taking statistical mechanical identifications of thermodynamic properties, explicitly developed for large systems, and applying them uncritically to small systems. There are no inconsistencies if thermodynamic properties are correctly identified and the distinction between thermodynamic properties and fluctuations is made clear