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Journal articles on the topic 'Extended moment invariants'
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1
Polihronov, J. "Incompressible flows: Relative scale invariance and isobaric polynomial fields." AIP Advances 12, no. 8 (2022): 085022. http://dx.doi.org/10.1063/5.0101855.
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This article examines the Bouton–Lie group invariants of the Navier–Stokes equation (NSE) for incompressible fluids. The theory is applied to the general scaling transformation admitted by the NSE: it adds new partial differential equations to the Navier–Stokes system of equations and is used to derive all self-similar solutions. This method can be applied to any differential equation exhibiting scaling invariance. The solutions are found to be based on isobaric polynomials, which can be smooth and nonzero at the initial moment. The non-self-similar velocity and pressure fields in the case of constant viscosity at all scales are studied and also found to be polynomials, nonzero, and smooth at the initial moment; they vanish far away from the origin and are not increasing in time. For a subset of the solutions, the cavitation number is shown to be a conserved quantity; the invariant analysis is extended to higher-dimensioned manifolds for the purpose of finding additional conserved quantities.
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Liang, Chen Hua, and Qing Chang. "Weighted Modified Hu Moment in Human Behavior Recognition." Advanced Materials Research 765-767 (September 2013): 2603–7. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.2603.
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t has been shown that the traditional seven Hu invariant moment does not have scaling invariance with low recognition rate in human behavior recognition. In order to improve the recognition rate, a human behavior recognition method will be put forward in this paper based on weighted modified Hu moments. Firstly, the traditional seven Hu moments will be extended to ten Hu moments to get more image details. Then, the extended Hu moments will be modified to make the Hu moments has the feature of scaling invariance. Lastly, the weighted modified Hu moment will be obtained through least squares method based on minimum variance criterion. The simulation of the sequence images shows that the weighted modified Hu moment can improve the recognition rate effectively.
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PODESTA, J. J. "Laws for third-order moments in homogeneous anisotropic incompressible magnetohydrodynamic turbulence." Journal of Fluid Mechanics 609 (July 31, 2008): 171–94. http://dx.doi.org/10.1017/s0022112008002280.
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It is known that Kolmogorov's four-fifths law for statistically homogeneous and isotropic turbulence can be generalized to anisotropic turbulence. This fundamental result for homogeneous anisotropic turbulence says that in the inertial range the divergence of the vector third-order moment 〈|δv(r)|2δv(r)〉 is constant and is equal to -4ϵ, where ϵ is the dissipation rate of the turbulence. This law can be extended to incompressible magnetohydrodyamic (MHD) turbulence where statistical isotropy is often not valid due, for example, to the presence of a large-scale magnetic field. Laws for anisotropic incompressible MHD turbulence were first derived by Politano and Pouquet. In this paper, the laws for vector third-order moments in homogeneous non-isotropic incompressible MHD turbulence are derived by a technique due to Frisch that clarifies the relationship between the energy flux in Fourier space and the vector third-order moments in physical space. This derivation is different from the original derivation of Politano and Pouquet which is based on the Kármán–Howarth equation, and provides some new physical insights. Separate laws are derived for the cascades of energy, cross-helicity and magnetic-helicity, the three ideal invariants of incompressible MHD for flows in three dimensions. These laws are of fundamental importance in the theory of MHD turbulence where non-isotropic turbulence is much more prevalent than isotropic turbulence.
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Iong, P. T., S. H. Chen, and Y. Yang. "Vision guidance of a fixed wing UAV using a single camera configuration." Aeronautical Journal 117, no. 1188 (2013): 147–73. http://dx.doi.org/10.1017/s0001924000007922.
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Abstract In this paper a single camera vision guidance system for fixed wing UAV is developed. This system searches for and identifies a target object with known colour and shape from images captured by an onboard camera. HSV colour space and moment invariants are utilised to describe the colour and shape features of the target object. Position, area and rotation angle of the target object in the image plane are collected. This information is then processed by the Extended Kalman Filter to estimate the relative positions and attitudes of the UAV. The vision guidance system guides the UAV towards the target object automatically based on these estimated states by using a proportional controller. A Senior Telemaster aircraft model kit installed with an onboard camera and computer is used for flight test. The target object for the flight test is a white flag with a red cross. Flight simulations and flight tests results are presented in this paper, showing that the vision guidance system can recognise the target object and guide the UAV effectively.
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Singh, Pawan Kumar, Ram Sarkar, and Mita Nasipuri. "Word-Level Script Identification Using Texture Based Features." International Journal of System Dynamics Applications 4, no. 2 (2015): 74–94. http://dx.doi.org/10.4018/ijsda.2015040105.
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Script identification is an appealing research interest in the field of document image analysis during the last few decades. The accurate recognition of the script is paramount to many post-processing steps such as automated document sorting, machine translation and searching of text written in a particular script in multilingual environment. For automatic processing of such documents through Optical Character Recognition (OCR) software, it is necessary to identify different script words of the documents before feeding them to the OCR of individual scripts. In this paper, a robust word-level handwritten script identification technique has been proposed using texture based features to identify the words written in any of the seven popular scripts namely, Bangla, Devanagari, Gurumukhi, Malayalam, Oriya, Telugu, and Roman. The texture based features comprise of a combination of Histograms of Oriented Gradients (HOG) and Moment invariants. The technique has been tested on 7000 handwritten text words in which each script contributes 1000 words. Based on the identification accuracies and statistical significance testing of seven well-known classifiers, Multi-Layer Perceptron (MLP) has been chosen as the final classifier which is then tested comprehensively using different folds and with different epoch sizes. The overall accuracy of the system is found to be 94.7% using 5-fold cross validation scheme, which is quite impressive considering the complexities and shape variations of the said scripts. This is an extended version of the paper described in (Singh et al., 2014).
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Premnath, Kannan N., and Sanjoy Banerjee. "Inertial Frame Independent Forcing for Discrete Velocity Boltzmann Equation: Implications for Filtered Turbulence Simulation." Communications in Computational Physics 12, no. 3 (2012): 732–66. http://dx.doi.org/10.4208/cicp.181210.090911a.
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AbstractWe present a systematic derivation of a model based on the central moment lattice Boltzmann equation that rigorously maintains Galilean invariance of forces to simulate inertial frame independent flow fields. In this regard, the central moments, i.e. moments shifted by the local fluid velocity, of the discrete source terms of the lattice Boltzmann equation are obtained by matching those of the continuous full Boltzmann equation of various orders. This results in an exact hierarchical identity between the central moments of the source terms of a given order and the components of the central moments of the distribution functions and sources of lower orders. The corresponding source terms in velocity space are then obtained from an exact inverse transformation due to a suitable choice of orthogonal basis for moments. Furthermore, such a central moment based kinetic model is further extended by incorporating reduced compressibility effects to represent incompressible flow. Moreover, the description and simulation of fluid turbulence for full or any subset of scales or their averaged behavior should remain independent of any inertial frame of reference. Thus, based on the above formulation, a new approach in lattice Boltzmann framework to incorporate turbulence models for simulation of Galilean invariant statistical averaged or filtered turbulent fluid motion is discussed.
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Toropov, Andrey A., Ozod M. Nabiev, Pablo Duchowicz, Eduardo A. Castro, and Francisco Torrens. "QSPR Modeling of Hydrocarbon Dipole Moments by Means of Correlation Weighting of Local Graph Invariants." Journal of Theoretical and Computational Chemistry 02, no. 02 (2003): 139–46. http://dx.doi.org/10.1142/s0219633603000409.
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Hydrocarbon dipole moments are calculated by means of correlation weighting of local graph invariants within the context of QSPR theory. This sort of flexible topological descriptor is used for several parameters: local invariants of k th vertex in the labeled hydrogen filled graph extended connectivity of zero-, first- and second-orders, number of paths of length 2 at k th vertex and valence shell of the k th vertex. The models predict hydrocarbon dipole moments in a quite sensible way. The best model is that one based upon numbers of path length 2 correlation weighting.
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Wang, Chunpeng, Hongling Gao, Meihong Yang, Jian Li, Bin Ma, and Qixian Hao. "Invariant Image Representation Using Novel Fractional-Order Polar Harmonic Fourier Moments." Sensors 21, no. 4 (2021): 1544. http://dx.doi.org/10.3390/s21041544.
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Continuous orthogonal moments, for which continuous functions are used as kernel functions, are invariant to rotation and scaling, and they have been greatly developed over the recent years. Among continuous orthogonal moments, polar harmonic Fourier moments (PHFMs) have superior performance and strong image description ability. In order to improve the performance of PHFMs in noise resistance and image reconstruction, PHFMs, which can only take integer numbers, are extended to fractional-order polar harmonic Fourier moments (FrPHFMs) in this paper. Firstly, the radial polynomials of integer-order PHFMs are modified to obtain fractional-order radial polynomials, and FrPHFMs are constructed based on the fractional-order radial polynomials; subsequently, the strong reconstruction ability, orthogonality, and geometric invariance of the proposed FrPHFMs are proven; and, finally, the performance of the proposed FrPHFMs is compared with that of integer-order PHFMs, fractional-order radial harmonic Fourier moments (FrRHFMs), fractional-order polar harmonic transforms (FrPHTs), and fractional-order Zernike moments (FrZMs). The experimental results show that the FrPHFMs constructed in this paper are superior to integer-order PHFMs and other fractional-order continuous orthogonal moments in terms of performance in image reconstruction and object recognition, as well as that the proposed FrPHFMs have strong image description ability and good stability.
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Pawlak, Mirosław, Gurmukh Singh Panesar, and Marcin Korytkowski. "A Novel Method for Invariant Image Reconstruction." Journal of Artificial Intelligence and Soft Computing Research 11, no. 1 (2021): 69–80. http://dx.doi.org/10.2478/jaiscr-2021-0005.
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AbstractIn this paper we propose a novel method for invariant image reconstruction with the properly selected degree of symmetry. We make use of Zernike radial moments to represent an image due to their invariance properties to isometry transformations and the ability to uniquely represent the salient features of the image. The regularized ridge regression estimation strategy under symmetry constraints for estimating Zernike moments is proposed. This extended regularization problem allows us to enforces the bilateral symmetry in the reconstructed object. This is achieved by the proper choice of two regularization parameters controlling the level of reconstruction accuracy and the acceptable degree of symmetry. As a byproduct of our studies we propose an algorithm for estimating an angle of the symmetry axis which in turn is used to determine the possible asymmetry present in the image. The proposed image recovery under the symmetry constraints model is tested in a number of experiments involving image reconstruction and symmetry estimation.
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MONEMZADEH, M., V. NIKOOFARD, and R. RAMEZANI-ARANI. "HAMILTONIAN EMBEDDING OF EINSTEIN–HILBERT ACTION IN (1+1) DIMENSIONS." Modern Physics Letters A 26, no. 26 (2011): 1995–2006. http://dx.doi.org/10.1142/s0217732311036358.
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Canonical analysis of constraint structure of Einstein–Hilbert action in (1+1) dimensions possesses a mixed constrained model. By means of finite order BFT approach in the extended phase space, it converts to a fully gauge-invariant model. Embedded Hamiltonian in this extended phase space is independent of momenta similar to the classical Hamiltonian.
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Bai, Shiyu, Weisong Wen, Yue Yu, and Li-Ta Hsu. "Invariant Extended Kalman Filtering for Pedestrian Deep-Inertial Odometry." International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-4-2024 (October 21, 2024): 607–12. http://dx.doi.org/10.5194/isprs-archives-xlviii-4-2024-607-2024.
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Abstract. Indoor localization for pedestrians, which relies solely on inertial odometry, has been a topic of great interest. Its significance lies in its ability to provide positioning solutions independently, without the need for external data. Although traditional strap-down inertial navigation shows rapid drift, the introduction of pedestrian dead reckoning (PDR), and artificial intelligence (AI) has enhanced the applicability of inertial odometry for indoor localization. However, inertial odometry continues to be affected by drift, inherent to the nature of dead reckoning. This implies that even a slight error at a given moment can lead to a significant decrease in accuracy after continuous integration operations. In this paper, we propose a novel approach aimed at enhancing the positioning accuracy of inertial odometry. Firstly, we derive a learning-based forward speed using inertial measurements from a smartphone. Unlike mainstream methods where the learned speed is directly used to determine the position, we use the forward speed combined with non-holonomic constraint (NHC) as a measurement to update the state predicted within a strap-down inertial navigation framework. Secondly, we employ an invariant extended Kalman filter (IEKF)-based state estimation to facilitate fusion to cope with the nonlinearity arising from the system and measurement model. Experimental tests are carried out in different scenarios using an iPhone 12, and traditional methods, including PDR, robust neural inertial navigation (RONIN), and the EKF-based method, are compared. The results suggest that the method we propose surpasses these traditional methods in performance.
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LEIVA, CARLOS. "EXTENDED CONFORMAL GROUP AND DSR VELOCITIES ON THE PHYSICAL SURFACE." International Journal of Modern Physics A 21, no. 13n14 (2006): 2863–76. http://dx.doi.org/10.1142/s0217751x06031053.
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The relation between conformal generators and Magueijo–Smolin Doubly Special Relativity term, is achieved. Through a dimensional reduction procedure, it is demonstrated that a massless relativistic particle living in a d-dimensional space, is isomorphic to the one living in a d+2 space with pure Lorentz invariance and to a particle living in a AdS d+1 space. To accomplish these identifications, the conformal group is extended and a nonlinear algebra is obtained. Finally, because the relation between momenta and velocities is known through the dimensional reduction procedure, the problem of position space dynamics is solved.
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Demetriou, P., S. Boffi, M. Radici, and R. F. Wagenbrunn. "Nucléon Electromagnetic Form Factors in a constituent-quark model." HNPS Proceedings 10 (December 5, 2019): 132. http://dx.doi.org/10.12681/hnps.2181.
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The electromagnetic form factors of the nucléon are calculated in an extended chiral constituent-quark model where the effective interaction is described by the exchange of pseudoscalar and vector mesons belonging to the pseudoscalar and pseudovector octet, respectively, and a scalar meson . Two-body current-density operators, constructed consistently with the extended model Hamiltonian in order to preserve gauge invariance and current conservation, are found to give a significant contribution to the nucléon magnetic form factors and improve the estimates of the nucleon magnetic moments.
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Louzada, Francisco, Pedro L. Ramos, and Gleici S. C. Perdoná. "Different Estimation Procedures for the Parameters of the Extended Exponential Geometric Distribution for Medical Data." Computational and Mathematical Methods in Medicine 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/8727951.
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We have considered different estimation procedures for the unknown parameters of the extended exponential geometric distribution. We introduce different types of estimators such as the maximum likelihood, method of moments, modified moments,L-moments, ordinary and weighted least squares, percentile, maximum product of spacings, and minimum distance estimators. The different estimators are compared by using extensive numerical simulations. We discovered that the maximum product of spacings estimator has the smallest mean square errors and mean relative estimates, nearest to one, for both parameters, proving to be the most efficient method compared to other methods. Combining these results with the good properties of the method such as consistency, asymptotic efficiency, normality, and invariance we conclude that the maximum product of spacings estimator is the best one for estimating the parameters of the extended exponential geometric distribution in comparison with its competitors. For the sake of illustration, we apply our proposed methodology in two important data sets, demonstrating that the EEG distribution is a simple alternative to be used for lifetime data.
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Bremigan, Ralph J. "Real Moment Map and Hyperkähler Geometry Techniques: The Cotangent Bundle to the 2-Sphere and SL(2, ℂ)-Adjoint Orbits". Algebra Colloquium 19, № 02 (2012): 181–218. http://dx.doi.org/10.1142/s1005386712000144.
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Going back to Kirwan and others, there is an established theory that uses moment map techniques to study actions by complex reductive groups on Kähler manifolds. Work of P. Heinzner, G. Schwarz, and H. Stötzel has extended this theory to actions by real reductive groups. In this paper, we apply these techniques to actions of the real group SU(1,1) ⊂ SL(2, ℂ) on a certain complex manifold of dimension two. More precisely, because of the SU(2)-invariant hyperkähler structure on this manifold, we are able to study a family of actions which includes and “interpolates” two well-known actions of SL(2, ℂ): the adjoint action on the orbit of a semisimple element of 𝔰𝔩(2, ℂ), and the action of SL(2, ℂ) on the cotangent bundle of the flag variety of SL(2, ℂ).
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Wilson, Adrian J., Robert M. Gifford, Henry Crosby, et al. "Changes in body composition and average daily energy expenditure of men and women during arduous extended polar travel." PLOS ONE 19, no. 10 (2024): e0308804. http://dx.doi.org/10.1371/journal.pone.0308804.
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Weight and skin-fold measurements were made at five-day intervals during a 47-day expedition by six men and three women from the edge of the sea ice to the South Pole. From these, together with detailed manual records of the nutrition for individual participants, the average daily energy expenditure was determined before and after a resupply at approximately mid-point of the expedition. For all participants body weight fell during the expedition with the overall loss being much smaller for the three female participants (-4.0, -4.0, -4.4kg) than for the male participants, (mean±sd) -8.6±2.0kg. Fat weight fell approximately linearly during the expedition with a total loss of (-4.1, -6.5 and -2.5kg) for the three female participants and -6.8±1.7kg for the male participants. Individual fat-free weight changed by a smaller amount overall: (0.13, 2.5 and -1.8kg) for the three female participants; -1.8±2.0kg for the male participants who, with one exception, lost fat-free tissue All participants showed a substantial variation in fat-free tissue weight during the expedition. Analysis of the daily energy expenditure showed adequate nutrition but the intake fell for the second part of the expedition although the reasons for this are unclear, but adaptation to the cold, altitude and workload are possible explanations. The validity of this time-averaged measurement for individual participants was determined from analysing moments about the mean of time-series actigraphy data from wrist worn devices. The mean and autocorrelation function of the actigraphy data across subjects were analysed to determine whether measures could be compared between participants. The first, second and third moment about the mean of the day-to-day activity was found to be time-invariant for individual subjects (χ2, p>0.05) and the normalized mean and autocorrelation measured over a day for each participant indistinguishable from the mean of the group (χ2, p>0.05) allowing both longitudinal and cross-sectional analysis.
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Zhu, Zun Shang, Yue Qiang Zhang, Xiang Zhou, and Yang Shang. "An Affine SIFT Matching Algorithm Based on Local Patch Shape Estimation." Applied Mechanics and Materials 519-520 (February 2014): 553–56. http://dx.doi.org/10.4028/www.scientific.net/amm.519-520.553.
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In this paper we present an affine SIFT matching method to achieve reliable correspondence points in stereo matching with large viewpoint changes. We extended the affine invariant of the conventional SIFT approach by estimating the shape of the local patch around the interest point. Since we can obtain the scale information by SIFT detector, a second moment matrix (SMM) descriptor was employed to describe the shape. Furthermore, by comparing the shapes of the potential matches, we can normalize the template of SIFT descriptor and obtain the initial affine transformation. At last, we applied the iterative based method to achieve a fine registration with the estimated initial transformation parameters. The experiment results show that the proposed method is more robust to viewpoint changes and the accuracy of registration is better than feature based methods.
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Lake, M. J. "A Solution to the Soccer Ball Problem for Generalized Uncertainty Relations." Ukrainian Journal of Physics 64, no. 11 (2019): 1036. http://dx.doi.org/10.15407/ujpe64.11.1036.
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We propose a new method for generating generalized uncertainty relations (GURs) including the generalized uncertainty principle (GUP), extended uncertainty principle (EUP), and extended generalized uncertainty principle (EGUP), previously proposed in the quantum gravity literature, without modifying the Heisenberg algebra. Our approach is compatible with the equivalence principle, and with local Poincar´e invariance in the relativistic limit, thus circumventing many of the problems associated with GURs derived from modified commutation relations. In particular, it does not require the existence of a nonlinear additional law for momenta. This allows sensible multi-particle states to be constructed in which the total momentum is macroscopic, even if the momentum of an individual particle is bounded by the Planck momentum, thus providing a resolution of the “soccer ball problem” that plagues current approaches to GURs.
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Burde, Georgy I. "Groups of Coordinate Transformations between Accelerated Frames." Symmetry 15, no. 6 (2023): 1226. http://dx.doi.org/10.3390/sym15061226.
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The analysis of the present paper reveals that, besides the relativistic symmetry expressed by the Lorentz group of coordinate transformations which leave invariant the Minkowski metric of space-time of inertial frames, there exists one more relativistic symmetry expressed by a group of coordinate transformations leaving invariant the space-time metric of the frames with a constant proper-acceleration. It is remarkable that, in the flat space-time, only those two relativistic symmetries, corresponding to groups of continuous transformations leaving invariant the metric of space-time of extended rigid reference frames, exist. Therefore, the new relativistic symmetry should be considered on an equal footing with the Lorentz symmetry. The groups of transformations leaving invariant the metric of the space-time of constant proper-acceleration are determined using the Lie group analysis, supplemented by the requirement that the group include transformations to or from an inertial to an accelerated frame. Two-parameter groups of two-dimensional (1 + 1), three-dimensional (2 + 1), and four-dimensional (3 + 1) transformations, with the group parameters related to the ratio of accelerations of the frames and the relative velocity of the frame space origins at the initial moment, can be considered as counterparts of the Lorentz group of corresponding dimensions. Defining the form of the interval and the groups of coordinate transformations satisfying the relativity principle paves the way to defining the invariant forms of the laws of dynamics and electrodynamics in accelerated frames. Thus, the problem of extending the relativity principle from inertial to uniformly accelerated frames has been resolved without use of the equivalence principle and/or the general relativity equations. As an application of the transformations to purely kinematic phenomena, the problem of differential aging between accelerated twins is treated.
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Peters, Norbert, Jonas Boschung, Michael Gauding, Jens Henrik Goebbert, Reginald J. Hill, and Heinz Pitsch. "Higher-order dissipation in the theory of homogeneous isotropic turbulence." Journal of Fluid Mechanics 803 (August 19, 2016): 250–74. http://dx.doi.org/10.1017/jfm.2016.489.
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The two-point theory of homogeneous isotropic turbulence is extended to source terms appearing in the equations for higher-order structure functions. For this, transport equations for these source terms are derived. We focus on the trace of the resulting equations, which is of particular interest because it is invariant and therefore independent of the coordinate system. In the trace of the even-order source term equation, we discover the higher-order moments of the dissipation distribution, and the individual even-order source term equations contain the higher-order moments of the longitudinal, transverse and mixed dissipation distribution functions. This shows for the first time that dissipation fluctuations, on which most of the phenomenological intermittency models are based, are contained in the Navier–Stokes equations. Noticeably, we also find the volume-averaged dissipation $\unicode[STIX]{x1D700}_{r}$ used by Kolmogorov (J. Fluid Mech., vol. 13, 1962, pp. 82–85) in the resulting system of equations, because it is related to dissipation correlations.
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Turvey, M. T., and Claudia Carello. "Obtaining information by dynamic (effortful) touching." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1581 (2011): 3123–32. http://dx.doi.org/10.1098/rstb.2011.0159.
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Dynamic touching is effortful touching. It entails deformation of muscles and fascia and activation of the embedded mechanoreceptors, as when an object is supported and moved by the body. It is realized as exploratory activities that can vary widely in spatial and temporal extents (a momentary heft, an extended walk). Research has revealed the potential of dynamic touching for obtaining non-visual information about the body (e.g. limb orientation), attachments to the body (e.g. an object's height and width) and the relation of the body both to attachments (e.g. hand's location on a grasped object) and surrounding surfaces (e.g. places and their distances). Invariants over the exploratory activity (e.g. moments of a wielded object's mass distribution) seem to ground this ‘information about’. The conception of a haptic medium as a nested tensegrity structure has been proposed to express the obtained information realized by myofascia deformation, by its invariants and transformations. The tensegrity proposal rationalizes the relative indifference of dynamic touch to the site of mechanical contact (hand, foot, torso or probe) and the overtness of exploratory activity. It also provides a framework for dynamic touching's fractal nature, and the finding that its degree of fractality may matter to its accomplishments.
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Brodsky, Stanley J. "Color Confinement, Hadron Dynamics, and Hadron Spectroscopy from Light-Front Holography and Superconformal Algebra." Advances in High Energy Physics 2018 (2018): 1–16. http://dx.doi.org/10.1155/2018/7236382.
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The QCD light-front Hamiltonian equation HLFΨ=M2Ψ derived from quantization at fixed LF time τ=t + z/c provides a causal, frame-independent method for computing hadron spectroscopy as well as dynamical observables such as structure functions, transverse momentum distributions, and distribution amplitudes. The QCD Lagrangian with zero quark mass has no explicit mass scale. de Alfaro, Fubini, and Furlan (dAFF) have made an important observation that a mass scale can appear in the equations of motion without affecting the conformal invariance of the action if one adds a term to the Hamiltonian proportional to the dilatation operator or the special conformal operator. If one applies the dAFF procedure to the QCD light-front Hamiltonian, it leads to a color-confining potential κ4ζ2 for mesons, where ζ2 is the LF radial variable conjugate to the qq¯ invariant mass squared. The same result, including spin terms, is obtained using light-front holography, the duality between light-front dynamics and AdS5, if one modifies the AdS5 action by the dilaton eκ2z2 in the fifth dimension z. When one generalizes this procedure using superconformal algebra, the resulting light-front eigensolutions provide a unified Regge spectroscopy of meson, baryon, and tetraquarks, including remarkable supersymmetric relations between the masses of mesons and baryons and a universal Regge slope. The pion qq¯ eigenstate has zero mass at mq=0. The superconformal relations also can be extended to heavy-light quark mesons and baryons. This approach also leads to insights into the physics underlying hadronization at the amplitude level. I will also discuss the remarkable features of the Poincaré invariant, causal vacuum defined by light-front quantization and its impact on the interpretation of the cosmological constant. AdS/QCD also predicts the analytic form of the nonperturbative running coupling αs(Q2)∝e-Q2/4κ2. The mass scale κ underlying hadron masses can be connected to the parameter ΛMS¯ in the QCD running coupling by matching the nonperturbative dynamics to the perturbative QCD regime. The result is an effective coupling αs(Q2) defined at all momenta. One obtains empirically viable predictions for spacelike and timelike hadronic form factors, structure functions, distribution amplitudes, and transverse momentum distributions. Finally, I address the interesting question of whether the momentum sum rule is valid for nuclear structure functions.
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GIELERAK, R., and P. ŁUGIEWICZ. "4D LOCAL QUANTUM FIELD THEORY MODELS FROM COVARIANT STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS I: GENERALITIES." Reviews in Mathematical Physics 13, no. 03 (2001): 335–408. http://dx.doi.org/10.1142/s0129055x01000685.
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A general class of covariant stochastic partial differential equations in Euclidean space-time dimension D=4 is selected and solutions of them are discussed. In particular we demonstrate a possibility of an analytic continuation of the moments of the constructed solutions to the Minkowski space-time. That gives rise to systems of tempered distributions obeying a substantial part of Wightman axioms. Specific models appropriate for vector, Higgs-like and Maxwell-like fields are described in detail. Covariant schemes for solving rectangular systems of equations are presented. Those ideas lead in particular to clarification of the concept of gauge-invariance in the present context. The explicit forms of Wightman distributions are obtained and used to prove the Hilbert Space Structure Condition. Some explicitly computable covariant models of extended random objects like loops, membranes and bags are presented.
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W Lee, Keum, and Sahjendra N Singh. "Immersion and invariance based adaptive attitude control of asteroid-orbiting spacecraft using modified Rodrigues parameters." Aeronautics and Aerospace Open Access Journal 5, no. 2 (2021): 57–64. http://dx.doi.org/10.15406/aaoaj.2021.05.00128.
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The attitude control of an asteroid-orbiting spacecraft based on immersion and invariance (I&I) theory is the subject of this paper. It is assumed that the moment of inertia matrix and the gravitational parameters are not known. The objective is to attain nadir pointing attitude on an elliptic orbit. First, based on the I&I principle, an adaptive attitude control system using the Modified Rodrigues Parameters (MRPs) is derived. Through the Lyapunov stability analysis, the asymptotic convergence of the MRP trajectories to the origin is established. Interestingly, in contrast to traditional adaptive systems, the trajectories of the closed-loop system converge to an attractive manifold in an extended state space. Then, for the purpose of comparison, this MRPs-based control law and a quaternions-based control system (also designed using the I&I principle) are simulated for the attitude control of the spacecraft in eccentric orbits around asteroid 433 Eros. It is observed that while each I&I-based control law can accomplish precise attitude control, for identical design parameters in these two control systems, the MRPs-based control law requires smaller control magnitude and accomplishes smoother convergence of trajectories to the attractive manifold, but requires larger settling time for the attitude trajectories, compared with the quaternions-based adaptive control law.
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AVDEEV, L. V., D. I. KAZAKOV, and I. N. KONDRASHUK. "DIFFICULTIES OF AN INFRARED EXTENSION OF DIFFERENTIAL RENORMALIZATION." International Journal of Modern Physics A 09, no. 07 (1994): 1067–96. http://dx.doi.org/10.1142/s0217751x94000492.
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We investigate the possibility of generalizing the differential renormalization of D. Z. Freedman, K. Johnson and J. I. Latorre in an invariant fashion to theories with infrared divergencies via an infrared [Formula: see text] operation. Two-dimensional σ models and the four-dimensional ɸ4-theory diagrams with exceptional momenta are used as examples, while dimensional renormalization serves as a test scheme for comparison. We write the basic differential identities of the method simultaneously in co-ordinate and momentum space, introducing two scales which remove ultraviolet and infrared singularities. A consistent set of Fourier-transformation formulae is derived. However, the values for tadpole-type Feynman integrals in higher orders of perturbation theory prove to be ambiguous, depending on the order of evaluation of the subgraphs. In two dimensions, even earlier than this ambiguity manifests itself, renormalization-group calculations based on the infrared extension of differential renormalization lead to incorrect results. We conclude that the procedure of extended differential renormalization does not perform the infrared [Formula: see text] operation in a self-consistent way.
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Shi, Dong Yan, Qing Shan Wang, and Xian Jie Shi. "Dynamic Analysis of T-Shaped Plate with General Boundary Conditions." Key Engineering Materials 572 (September 2013): 509–12. http://dx.doi.org/10.4028/www.scientific.net/kem.572.509.
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In this investigation, an analytical method is proposed for the dynamic analysis of T-shaped plates with general boundary conditions. Four types of springs are uniformly distributed along each edge, which are used to simulate the transverse shearing forces, bending moments, in-plane longitudinal forces and in-plane shearing forces, respectively. Arbitrary boundary conditions can be readily realized by setting the stiffness of the four types restraining springs. The interactions between the plates have been taken into account at the junction with four types of coupling springs. The in-plane and out-of-plane displacements are invariantly expressed, regardless of boundary conditions, as a new form of double Fourier series with a drastically improved convergence as compared with the traditional Fourier series. The expansion coefficients are considered as the generalized coordinates, and determined using the Rayleigh-Ritz technique. Numerical examples are presented to validate the accuracy and reliability of the proposed method. A good agreement is observed between the current results and FEA results. The present method can be directly extended to more complicated structures with any number of plates.
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Tao, Chen, Jialiang Lu, Miao Su, and Xinghua Hong. "Modeling and refactoring the indigo patterns." Journal of Engineered Fibers and Fabrics 14 (January 2019): 155892501988397. http://dx.doi.org/10.1177/1558925019883971.
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For purpose of reconstruction and innovation of indigo patterns, this study explores modeling, reconstruction, and assembling of the pattern elements by means of mathematics. A model for indigo pattern elements is proposed based on cardinal splines, in which the rigidity of shape is conveyed by the tension coefficient, and the concavity and variety by configuration of the knots. The generalized version of this model is capable of covering any complex element. The contour tracing technique is employed to extract pattern elements from the image, and the closest model instance is selected in virtue of invariance of the improved Hu moments. The selected instances are transformed with respect to the geometric center, the coverage, and the coincidence to match the pattern elements in the image so as to reconstruct the whole pattern. The element filters are conducted on the reconstructed patterns to modify the elements and produce new innovative patterns of constant skeleton. The model is borrowed serving as a skeleton in element assembling. The skeleton properties are investigated to provide basis for skeleton embodiment in which these properties are involved into establishing the placement determiner and element determiner so as to carry out the assembling of elements. Also discussed is the extended skeleton which goes beyond the model and brings about variety and flexibility to element assembling. It is turned out that reconstruction with the model well implements a mathematical copy of the pattern, and the assembling of elements by skeletons provides rich possibilities to innovation of indigo patterns.
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Tishchenko, Aramis Viktorovich, Anatoly Mikhailovich Kulabukhov, and Victor Alexandrovich Masalskiy. "SYNTHESIS OF AN ADAPTIVE AUTOMATIC SYSTEM OF AIRCRAFT CONTROLS WITH MULTIDIMENSIONAL PI-REGULATOR." Journal of Rocket-Space Technology 27, no. 4 (2019): 79–85. http://dx.doi.org/10.15421/51913.
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The article presents the synthesis of a functional diagram of an adaptive automatic control system (ACS) for controlling an aircraft with an automatically reconfigurable multidimensional PI controller, which provides the minimum static and minimum mean square error of control with minimal energy consumption for the formation of the control exposure. The synthesis of ACS algorithms is performed as a result of solving the problem of conditionally minimizing the quadratic functional of the generalized work (taking into account restrictions on state variables and control actions given by differential equations of the control object (CO) and inequalities). The mathematical description of the multidimensional CO is carried out using the CO model in the state space, which automatically takes into account the mutual influence of individual control loops on each other. As the state variables of the aircraft, linear displacements, speeds and accelerations of the center of mass of the aircraft, and angular displacements, speeds and accelerations of the rotational movement of the aircraft relative to the center of mass are used. The matrix equation of dynamics of the aircraft is formed by a system of nonlinear differential equations of the first order of forces and moments of forces acting on the aircraft. To ensure the minimum static control error, integrators are included in the ACS (for each control action). The algorithm for the formation of control actions of the extended CO, providing the declared properties of the ACS, is obtained as a result of solving the problem of conditional minimization of the generalized work functional. The task of conditional minimization of a functional with constraints is performed by the maximum principle. The resulting two-point boundary value problem is transformed by the invariant immersion method into a Cauchy problem for optimal values of state variables. The evaluation of the characteristics of a specific adaptive ACS for the spacecraft is expected to be obtained as a result of further research by mathematical modeling.
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PANDYA, R. V. R., and F. MASHAYEK. "Non-isothermal dispersed phase of particles in turbulent flow." Journal of Fluid Mechanics 475 (January 25, 2003): 205–45. http://dx.doi.org/10.1017/s0022112002002781.
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In this paper we consider, for modelling and simulation, a non-isothermal turbulent flow laden with non-evaporating spherical particles which exchange heat with the surrounding fluid and do not collide with each other during the course of their journey under the influence of the stochastic fluid drag force. In the modelling part of this study, a closed kinetic or probability density function (p.d.f.) equation is derived which describes the distribution of position x, velocity v, and temperature θ of the particles in the flow domain at time t. The p.d.f. equation represents the transport of the ensemble-average (denoted by 〈 〉) phase-space density 〈W(x, v, θ, t)〉. The process of ensemble averaging generates unknown terms, namely the phase-space diffusion current j = βv〈u′W〉 and the phase-space heat current h = βθ〈t′W〉, which pose closure problems in the kinetic equation. Here, u′ and t′ are the fluctuating parts of the velocity and temperature, respectively, of the fluid in the vicinity of the particle, and βv and βθ are inverse of the time constants for the particle velocity and temperature, respectively. The closure problems are first solved for the case of homogeneous turbulence with uniform mean velocity and temperature for the fluid phase by using Kraichnan’s Lagrangian history direct interaction (LHDI) approximation method and then the method is generalized to the case of inhomogeneous flows. Another method, which is due to Van Kampen, is used to solve the closure problems, resulting in a closed kinetic equation identical to the equation obtained by the LHDI method. Then, the closed equation is shown to be compatible with the transformation constraint that is proposed by extending the concept of random Galilean transformation invariance to non-isothermal flows and is referred to as the ‘extended random Galilean transformation’ (ERGT). The macroscopic equations for the particle phase describing the time evolution of statistical properties related to particle velocity and temperature are derived by taking various moments of the closed kinetic equation. These equations are in the form of transport equations in the Eulerian framework, and are computed for the case of two-phase homogeneous shear turbulent flows with uniform temperature gradients. The predictions are compared with the direct numerical simulation (DNS) data which are generated as another part of this study. The predictions for the particle phase require statistical properties of the fluid phase which are taken from the DNS data. In DNS, the continuity, Navier–Stokes, and energy equations are solved for homogeneous turbulent flows with uniform mean velocity and temperature gradients. For the mean velocity gradient along the x2- (cross-stream) axis, three different cases in which the mean temperature gradient is along the x1-, x2-, and x3-axes, respectively, are simulated. The statistical properties related to the particle phase are obtained by computing the velocity and temperature of a large number of particles along their Lagrangian trajectories and then averaging over these trajectories. The comparisons between the model predictions and DNS results show very encouraging agreement.
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Hamid, Reza Boveiri. "Persian Printed Numerals Classification Using Extended Moment Invariants." March 24, 2010. https://doi.org/10.5281/zenodo.1082017.
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Classification of Persian printed numeral characters has been considered and a proposed system has been introduced. In representation stage, for the first time in Persian optical character recognition, extended moment invariants has been utilized as characters image descriptor. In classification stage, four different classifiers namely minimum mean distance, nearest neighbor rule, multi layer perceptron, and fuzzy min-max neural network has been used, which first and second are traditional nonparametric statistical classifier. Third is a well-known neural network and forth is a kind of fuzzy neural network that is based on utilizing hyperbox fuzzy sets. Set of different experiments has been done and variety of results has been presented. The results showed that extended moment invariants are qualified as features to classify Persian printed numeral characters.
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Komech, A. I., and E. A. Kopylova. "On the Stability of Solitons for the Maxwell-Lorentz Equations with Rotating Particle." Milan Journal of Mathematics, March 20, 2023. http://dx.doi.org/10.1007/s00032-022-00372-z.
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AbstractWe prove the stability of solitons of the Maxwell–Lorentz equations with extended charged rotating particle. The solitons are solutions which correspond to the uniform rotation of the particle. To prove the stability, we construct the Hamilton–Poisson representation of the Maxwell–Lorentz system. The construction relies on the Hamilton least action principle. The constructed structure is degenerate and admits a functional family of the Casimir invariants. This structure allows us to construct the Lyapunov function corresponding to a soliton. The function is a combination of the Hamiltonian with a suitable Casimir invariant. The function is conserved, and the soliton is its critical point. The key point of the proof is a lower bound for the Lyapunov function. This bound implies that the soliton is a strict local minimizer of the function. The bound holds if the effective moment of inertia of the particle in the Maxwell field is sufficiently large with respect to the “bar moment of inertia".
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Freidel, Laurent, Seyed Faroogh Moosavian та Daniele Pranzetti. "On the Definition of the Spin Charge in Asymptotically-Flat Spacetimes". Classical and Quantum Gravity, 13 листопада 2024. http://dx.doi.org/10.1088/1361-6382/ad9216.
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Abstract We propose a solution to a classic problem in gravitational physics consisting of defining the spin associated with asymptotically-flat spacetimes. We advocate that the correct asymptotic symmetry algebra to approach this problem is the generalized‒BMS algebra gbms instead of the BMS algebra used hitherto in the literature for which a notion of spin is generically unavailable. We approach the problem of defining the spin charges from the perspective of coadjoint orbits of gbms and construct the complete set of Casimir invariants that determine gbms coadjoint orbits, using the notion of vorticity for gbms. This allows us to introduce spin charges for gbms as the generators of area-preserving diffeomorphisms forming its isotropy subalgebra. To elucidate the parallelism between our analysis and the Poincaré case, we clarify several features of the Poincaré embedding in gbms and reveal the presence of condensate fields associated with the symmetry breaking from gbms to Poincaré. We also introduce the notion of a rest frame available only for this extended algebra. This allows us to construct, from the spin generator, the gravitational analog of the Pauli‒Lubański pseudo-vector. Finally, we obtain the gbms moment map, which we use to construct the gravitational spin-charges and gravitational Casimirs from their dual algebra counterparts.
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Bhatt, Shikha, and B. C. Chanyal. "Generalized quaternionic free rotational Dirac equation and spinor solutions in the electromagnetic field." International Journal of Geometric Methods in Modern Physics, April 5, 2022. http://dx.doi.org/10.1142/s0219887822501031.
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Starting with the quaternionic Minkowski space–time and its four-vector representation, a rotational analogue of the quaternionic Dirac equation in the electromagnetic field is developed, which includes not only the energy solutions but also the angular momentum solutions for rotating Dirac fermions. The striking feature of the quaternionic approach is that it depicts a unified representation of energy–momentum in a single framework as the space–time. Furthermore, we establish the generalized Schrodinger–Pauli-like equation associated with generalized electric and magnetic dipole energies that corresponds to their dipole moments. As such, the present analysis deals with the invariant behavior of the extended quaternionic rotational Dirac equation under Lorentz–Poincaré, Gauge, duality, and CPT invariance.
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Baake, Olaf, and Mokhtar Hassaine. "Rotating stealth black holes with a cohomogeneity$$-1$$ metric." European Physical Journal C 81, no. 7 (2021). http://dx.doi.org/10.1140/epjc/s10052-021-09449-2.
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AbstractIn five dimensions we consider a general shift symmetric and parity preserving scalar tensor action that contains up to second order covariant derivatives of the scalar field. A rotating stealth black hole solution is constructed where the metric is given by the Myers–Perry spacetime with equal momenta and the scalar field is identified with the Hamilton–Jacobi potential. This nontrivial scalar field has an extra hair associated with the rest mass of the test particle, and the solution does not require any fine tuning of the coupling functions of the theory. Interestingly enough, we show that the disformal transformation, generated by this scalar field, and with a constant degree of disformality, leaves invariant (up to diffeomorphisms) the Myers–Perry metric with equal momenta. This means that the hair of the scalar field, along with the constant disformality parameter, can be consistently absorbed into further redefinitions of the mass and of the single angular parameter of the disformed metric. These results are extended in higher odd dimensions with a Myers–Perry metric for which all the momenta are equal. The key of the invariance under disformal transformation of the metric is mainly the cohomogeneity$$-1$$ - 1 character of the Myers–Perry metric with equal momenta. Starting from this observation, we consider a general class of cohomogeneity$$-1$$ - 1 metrics in arbitrary dimension, and we list the conditions ensuring that this class of metrics remain invariant (up to diffeomorphisms) under a disformal transformation with a constant degree of disformality and with a scalar field with constant kinetic term. The extension to the Kerr+-de Sitter case is also considered where it is shown that rotating stealth solutions may exist provided some fine tuning of the coupling functions of the scalar tensor theory.
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Ashmore, Anthony, Charles Strickland-Constable, David Tennyson, and Daniel Waldram. "Heterotic backgrounds via generalised geometry: moment maps and moduli." Journal of High Energy Physics 2020, no. 11 (2020). http://dx.doi.org/10.1007/jhep11(2020)071.
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Abstract We describe the geometry of generic heterotic backgrounds preserving minimal supersymmetry in four dimensions using the language of generalised geometry. They are characterised by an SU(3) × Spin(6 + n) structure within O(6, 6 + n) × ℝ+ generalised geometry. Supersymmetry of the background is encoded in the existence of an involutive subbundle of the generalised tangent bundle and the vanishing of a moment map for the action of diffeomorphisms and gauge symmetries. We give both the superpotential and the Kähler potential for a generic background, showing that the latter defines a natural Hitchin functional for heterotic geometries. Intriguingly, this formulation suggests new connections to geometric invariant theory and an extended notion of stability. Finally we show that the analysis of infinitesimal deformations of these geometric structures naturally reproduces the known cohomologies that count the massless moduli of supersymmetric heterotic backgrounds.
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Integral, square error, Least-squares, Markovparameters, matching Moment, and reduction. Order. "Order Reduction by Least-Squares Methods about General Point ''a''." February 25, 2007. https://doi.org/10.5281/zenodo.1080074.
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The concept of order reduction by least-squares moment matching and generalised least-squares methods has been extended about a general point ?a?, to obtain the reduced order models for linear, time-invariant dynamic systems. Some heuristic criteria have been employed for selecting the linear shift point ?a?, based upon the means (arithmetic, harmonic and geometric) of real parts of the poles of high order system. It is shown that the resultant model depends critically on the choice of linear shift point ?a?. The validity of the criteria is illustrated by solving a numerical example and the results are compared with the other existing techniques.
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Szabados, László B. "Three-Space from Quantum Mechanics." Foundations of Physics 52, no. 5 (2022). http://dx.doi.org/10.1007/s10701-022-00617-2.
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AbstractThe spin geometry theorem of Penrose is extended from SU(2) to E(3) (Euclidean) invariant elementary quantum mechanical systems. Using the natural decomposition of the total angular momentum into its spin and orbital parts, the distance between the centre-of-mass lines of the elementary subsystems of a classical composite system can be recovered from their relative orbital angular momenta by E(3)-invariant classical observables. Motivated by this observation, an expression for the ‘empirical distance’ between the elementary subsystems of a composite quantum mechanical system, given in terms of E(3)-invariant quantum observables, is suggested. It is shown that, in the classical limit, this expression reproduces the a priori Euclidean distance between the subsystems, though at the quantum level it has a discrete character. ‘Empirical’ angles and 3-volume elements are also considered.
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Nugara, Vincenzo, Salvatore Plumari, Lucia Oliva, and Vincenzo Greco. "Far-from-equilibrium attractors with full relativistic Boltzmann approach in boost-invariant and non-boost-invariant systems." European Physical Journal C 84, no. 8 (2024). http://dx.doi.org/10.1140/epjc/s10052-024-13227-1.
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AbstractWe study the universal behavior associated with a Relativistic Boltzmann Transport (RBT) approach with the full collision integral in 0+1D conformal systems. We show that all momentum moments of the distribution function exhibit universal behavior. Furthermore, the RBT approach allows to calculate the full distribution function, showing that an attractor behavior is present in both the longitudinal and transverse momentum dependence. We compare our results to the far-from-equilibrium attractors determined with other approaches, such as kinetic theory in Relaxation Time Approximation (RTA) and relativistic hydrodynamic theories, both in their viscous (DNMR) an anisotropic (aHydro) formulations, finding a very similar evolution, but an even faster thermalization in RBT for higher order moments. For the first time, we extended this analysis also to study the attractor behavior under a temperature-dependent viscosity $$\eta /s(T)$$ η / s ( T ) , accounting also for the rapid increase toward the hadronic phase. We find that a partial breaking of the scaling behavior with respect to $$\tau /\tau _{eq}$$ τ / τ eq emerges only at $$T \approx T_c$$ T ≈ T c generating a transient deviation from attractors; interestingly this in realistic finite systems may occur around the freeze-out dynamics. Finally, we investigate for the first time results beyond the boost-invariant picture, finding that also in such a case the system evolves toward the universal attractor. In particular, we present the forward and pull-back attractors at different space-time rapidities including rapidity regions where initially the distribution function is even vanishing.
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Rong, YongFeng, and Wusheng Chou. "Design and Control of an Aerial Manipulator with Invariant Center of Gravity for Physical Interaction." Journal of Mechanisms and Robotics, September 7, 2023, 1–17. http://dx.doi.org/10.1115/1.4063368.
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Abstract The deployment of manipulators enhances the versatility and flexibility of unmanned aerial vehicles (UAVs) in aerial physical interaction tasks but also challenges their designs and controls due to variations in the center of gravity (CoG), moment of inertia and reaction wrenches. This work presents a novel design of a two-degree-of-freedom dual-tool manipulator with invariant-center-of-gravity (ICoG) property. The ICoG conditions are strictly deduced, and a practical optimization-based parameter tuning method is proposed. A novel adaptive-extended-state-observer-based (AESO-based) impedance control method is developed with actuator dynamics taken into account. The AESO can estimate and compensate for both the lumped disturbance, including the influences of moment-of-inertia variation and counter torque, and the unmeasurable states for the controller. In addition, a switching adaptive law is proposed to attenuate the peaking phenomenon under high observer gains. The impedance controller is designed using an auxiliary impedance tracking error to overcome the difficulty of the increased system order. The Lyapunov approach is used to evaluate the stability of the entire system. The proposed approach is implemented on a fully-actuated hexarotor with a prototype of the ICoG manipulator. Comparative experiments are conducted to validate the effectiveness and advantages of the proposed design and control methods.
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Gao, Jing, Xiao-Fang Han, Jinghong Ma, Lei Wang, and Haotian Xu. "95 GeV Higgs boson and spontaneous CP -violation at the finite temperature." Physical Review D 110, no. 11 (2024). https://doi.org/10.1103/physrevd.110.115045.
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The ATLAS and CMS collaborations reported a diphoton excess in the invariant mass distribution around the 95.4 GeV with a local significance of 3.1σ. Moreover, there is another 2.3σ local excess in the bb¯ final state at large electron-positron collider in the same mass region. A plausible solution is that the Higgs sector is extended to include an additional Higgs boson with a mass of 95.4 GeV. We study a complex singlet scalar extension of the two-Higgs-doublet model in which the 95.4 GeV Higgs is from the mixing of three CP-even Higgs fields. In addition, the extended Higgs potential can achieve spontaneous CP-violation at the finite temperature and restore CP symmetry at the present temperature of the Universe. We find that the model can simultaneously explain the baryon asymmetry of the Universe, the diphoton and bb¯ excesses around the 95.4 GeV while satisfying various relevant constraints including the experiments of collider and electric dipole moment. Published by the American Physical Society 2024
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Li, Hang, and P. Wang. "Nonlocal QED and lepton g-2 anomalies." European Physical Journal C 84, no. 7 (2024). http://dx.doi.org/10.1140/epjc/s10052-024-13013-z.
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AbstractQuantum electrodynamics is generally extended to a nonlocal QED by introducing the correlation functions. The gauge link is introduced to guarantee that the nonlocal QED is locally U(1) gauge invariant. The corresponding Feynman rules as well as the proof of Ward–Takahashi identity are presented. As an example, the anomalous magnetic moments of leptons are studied in nonlocal QED. At one-loop level, besides the ordinary diagrams, there are many additional Feynman diagrams which are generated from the gauge link. It shows the nonlocal QED can provide a reasonable explanation for lepton $$g-2$$ g - 2 anomalies.
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Shang, Ce, Shuo Liu, Caigui Jiang, et al. "Observation of a Higher‐Order End Topological Insulator in a Real Projective Lattice." Advanced Science, January 12, 2024. http://dx.doi.org/10.1002/advs.202303222.
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AbstractThe modern theory of quantized polarization has recently extended from 1D dipole moment to multipole moment, leading to the development from conventional topological insulators (TIs) to higher‐order TIs, i.e., from the bulk polarization as primary topological index, to the fractional corner charge as secondary topological index. The authors here extend this development by theoretically discovering a higher‐order end TI (HOETI) in a real projective lattice and experimentally verifying the prediction using topolectric circuits. A HOETI realizes a dipole‐symmetry‐protected phase in a higher‐dimensional space (conventionally in one dimension), which manifests as 0D topologically protected end states and a fractional end charge. The discovered bulk‐end correspondence reveals that the fractional end charge, which is proportional to the bulk topological invariant, can serve as a generic bulk probe of higher‐order topology. The authors identify the HOETI experimentally by the presence of localized end states and a fractional end charge. The results demonstrate the existence of fractional charges in non‐Euclidean manifolds and open new avenues for understanding the interplay between topological obstructions in real and momentum space.
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Antusch, Stefan, Oliver Fischer, A. Hammad, and Christiane Scherb. "Explaining excesses in four-leptons at the LHC with a double peak from a CP violating Two Higgs Doublet Model." Journal of High Energy Physics 2022, no. 8 (2022). http://dx.doi.org/10.1007/jhep08(2022)224.
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Abstract Extended scalar sectors with additional degrees of freedom appear in many scenarios beyond the Standard Model. Heavy scalar resonances that interact with the neutral current could be discovered via broad resonances in the tails of the four-lepton invariant mass spectrum, where the Standard Model background is small and well understood. In this article we consider a recent ATLAS measurement of four-lepton final states, where the data is in excess over the background for invariant masses above 500 GeV. We discuss the possibility that this excess could be interpreted as a “double peak” from the two extra heavy neutral scalars of a CP violating Two Higgs Doublet Model, both coupling to the Z boson. We apply an iterative fitting procedure to find viable model parameters that can match the excess, resulting in a benchmark point where the observed four-lepton invariant mass spectrum can be explained by two scalar particles H2 and H3, with masses of 544 GeV and 629 GeV, respectively, being admixtures of the CP eigenstates. Our explanation predicts additional production processes for $$ t\overline{t} $$ t t ¯ , W+W−, 4b and γγ, some of which have cross sections close to the current experimental limits. Our results further imply that the electric dipole moment of the electron should be close to the present bounds.
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Akl Ahmed, Doaa. "Modelling the Density of Inflation Using Autoregressive Conditional Heteroscedasticity, Skewness, and Kurtosis Models." Ensayos Revista de Economía 30, no. 2 (2011). http://dx.doi.org/10.29105/ensayos30.2-1.
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The paper aimed at modelling the density of inflation based on time-varying conditional variance, skewness and kurtosis model developed by Leon, Rubio, and Serna (2005) who model higher-order moments as GARCH-type processes by applying a Gram-Charlier series expansion of the normal density function. Additionally, it extended their work by allowing both conditional skewness and kurtosis to have an asymmetry term. The results revealed the significant persistence in conditional variance, skewness and kurtosis which indicate high asymmetry of inflation. Additionally, diagnostic tests reveal that models with nonconstant volatility, skewness and kurtosis are superior to models that keep them invariant. JEL Classification: C13, E31, E37.
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Han, Qi, Zhitao Liu, Hongye Su, and Xiangbin Liu. "Adaptive trajectory tracking control for VTOL UAVs with unknown time‐varying mass using an extended I&I estimator." International Journal of Adaptive Control and Signal Processing, January 14, 2024. http://dx.doi.org/10.1002/acs.3746.
Full textAbstract:
SummaryThis article presents an adaptive control scheme for vertical takeoff and landing unmanned aerial vehicles subject to time‐varying mass based on the immersion and invariance scheme in an extended form. For the varying mass parameter in the position control, a generalized I&I adaptive law is proposed with higher dimension to estimate the mass and its derivatives. The stability of the resulting estimation error manifold, which is in a cascade form, is guaranteed by introducing smooth saturation functions in the position control law. The attitude control is designed by employing a smooth function with positive integrable time‐varying function to compensate unknown time‐varying moment of inertia to achieve asymptotic attitude tracking. Simulation and experimental results verify the effectiveness of the proposed method under different cases, and the robustness to time‐varying parameter is assured.
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Bhadury, Samapan. "Relativistic spin hydrodynamics with momentum- and spin-dependent relaxation time." Physical Review C 111, no. 3 (2025). https://doi.org/10.1103/physrevc.111.034909.
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Using the extended relaxation time approximation along with the theory of semiclassical spin, a framework of relativistic dissipative spin hydrodynamics is developed such that the relaxation time can depend on the momenta and spin of the constituent spin-1/2 particles. A general definition of the fluid four-velocity is considered, allowing the theory to be valid in a general frame and matching conditions. Consequently, the frame-invariant bulk, shear, particle diffusion, and spin transport coefficients are obtained, showing that the evolution of fluid remains unaffected by spin in the limit of small polarization as was the case where the relaxation time was independent of spin or momentum. Published by the American Physical Society 2025
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Li, Jianqing, Changsheng Gao, Tianming Feng, and Wuxing Jing. "Novel Moving Mass Flight Vehicle and Its Equivalent Experiment." Journal of Dynamic Systems, Measurement, and Control 140, no. 11 (2018). http://dx.doi.org/10.1115/1.4040326.
Full textAbstract:
This paper presents a novel configuration of flight vehicle with moving mass control. We focus on the development of the proposed control mechanism and investigate the feasibility of an equivalent experimental setup. First, the effect of the moving mass parameters on the control authority is investigated. Then, a control law based on immersion and invariance (I&I) theory is presented for the moving mass control system. In the design process, we select a first-order target system to reduce the difficulty of controller design. To deal with the coupling caused by the additional inertia moment, which is generated by the motion of the moving mass, the extended state observer (ESO) is designed. The proposed adaptive controller is simulated and tested on the experimental setup. Finally, the simulation results validate the quality of the proposed adaptive controller, which ensures a good performance in the novel configuration with internal moving mass.
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Wang, Zhigang, Zhichao Lyu, Dengyan Duan, and Jianbo Li. "A novel system identification algorithm for quad tilt-rotor based on neural network with foraging strategy." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, December 8, 2020, 095441002097659. http://dx.doi.org/10.1177/0954410020976598.
Full textAbstract:
Quad tilt-rotor(QTR) UAV is a nonlinear time-varying system in full flight mode. It is difficult and inaccurate to model the nonlinear time-varying system, which cannot fully reflect the problem of controlling input and system response output in the full flight mode. In order to solve the above problems, a novel neural network model was adopt to identify the nonlinear time-varying system of quad tilt-rotor in full flight mode. An adaptive learning rate algorithm based on foraging strategy is proposed based on the global error BP neural network. Corresponding to the nonlinear time-varying system, BP neural network is set as the time-invariant system structure with constant network structure and continuously changing weights at multiple times, and the nonlinear input-output relationship under the time-varying system is jointly described by fitting the network at all times. The extended Kalman filtering algorithm is used to track the network connection weights by modifying the network weights at the current moment with the input and output data at the next moment. The final identification result shows that the smaller mean square error of both only transition process and full flight mode, shows that using this optimization algorithm can well describe the input and output characteristics of the nonlinear time-varying systems. When the same network structure is adopted, no matter for transition mode or full mode, the BP optimization algorithm based on foraging strategy is better than the global BP algorithm for system identification of the full mode quad tilt-rotor. Therefore, when the BP neural network based on foraging strategy is adopted, the same network structure can be adopted to systematically identify the full mode of quad tilt-rotor by changing the weight.
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Ma, Chen-Te, and Franco Pezzella. "More stringy effects in target space from Double Field Theory." Journal of High Energy Physics 2020, no. 8 (2020). http://dx.doi.org/10.1007/jhep08(2020)113.
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Abstract In Double Field Theory, the mass-squared of doubled fields associated with bosonic closed string states is proportional to NL + NR− 2. Massless states are therefore not only the graviton, anti-symmetric, and dilaton fields with (NL = 1, NR = 1) such theory is focused on, but also the symmetric traceless tensor and the vector field relative to the states (NL = 2, NR = 0) and (NL = 0, NR = 2) which are massive in the lower-dimensional non-compactified space. While they are not even physical in the absence of compact dimensions, they provide a sample of states for which both momenta and winding numbers are non-vanishing, differently from the states (NL = 1, NR = 1). A quadratic action is therefore here built for the corresponding doubled fields. It results that its gauge invariance under the linearized double diffeomorphisms is based on a generalization of the usual weak constraint, giving rise to an extra mass term for the symmetric traceless tensor field, not otherwise detectable: this can be interpreted as a mere stringy effect in target space due to the simultaneous presence of momenta and windings. Furthermore, in the context of the generalized metric formulation, a non-linear extension of the gauge transformations is defined involving the constraint extended from the weak constraint that can be uniquely defined in triple products of fields. Finally, we show that the above mentioned stringy effect does not appear in the case of only one compact doubled space dimension.
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Gaur, Himanshu. "Total and symmetry resolved entanglement spectra in some fermionic CFTs from the BCFT approach." Journal of High Energy Physics 2024, no. 9 (2024). http://dx.doi.org/10.1007/jhep09(2024)173.
Full textAbstract:
Abstract In this work, we study the universal total and symmetry-resolved entanglement spectra for a single interval of some 2d Fermionic CFTs using the Boundary Conformal Field theory (BCFT) approach. In this approach, the partition of Hilbert space is achieved by cutting out discs around the entangling boundary points and imposing boundary conditions preserving the extended symmetry under scrutiny. The reduced density moments are then related to the BCFT partition functions and are also found to be diagonal in the symmetry charge sectors. In particular, we first study the entanglement spectra of massless Dirac fermion and modular invariant Z2-gauged Dirac fermion by considering the boundary conditions preserving either the axial or the vector U(1) symmetry. The total entanglement spectra of the modular invariant Z2-gauged Dirac fermion are shown to match with the compact boson result at the compactification radius where the Bose-Fermi duality holds, while for the massless Dirac fermion, it is found that the boundary entropy term doesn’t match with the self-dual compact boson. The symmetry-resolved entanglement is found to be the same in all cases, except for the charge spectrum which is dependent on both the symmetry and the theory. We also study the entanglement spectra of N massless Dirac fermions by considering boundary conditions preserving different chiral U(1)N symmetries. Entanglement spectra are studied for U(1)M subgroups, where M ≤ N, by imposing boundary conditions preserving different chiral symmetries. The total entanglement spectra are found to be sensitive to the representations of the U(1)M symmetry in the boundary theory among other behaviours at O(1). Similar results are also found for the Symmetry resolved entanglement entropies. The characteristic log log (ℓ/ϵ) term of the U(1) symmetry is found to be proportional to M in the symmetry-resolved entanglement spectra.