Miracle-dz/UniFAR-FTUs huggingface dataset:
Random walks exhibiting anomalous diffusion: elephants, urns and the limits of normality

A random walk model is presented which exhibits a transition from standard to anomalous diffusion as a parameter is varied. The model is a variant on the elephant random walk and differs in respect of the treatment of the initial state, which in the present work consists of a given number N of fixed steps. This also links the elephant random walk to other types of history dependent random walk. As well as being amenable to direct analysis, the model is shown to be asymptotically equivalent to a non-linear urn process. This provides fresh insights into the limiting form of the distribution of the walker’s position at large times. Although the distribution is intrinsically non-Gaussian in the anomalous diffusion regime, it gradually reverts to normal form when N is large under quite general conditions.
Extending the coverage area of regional ionosphere maps using a support vector machine algorithm

Abstract. The coverage of regional ionosphere maps is determined by the distribution of ground-based monitoring stations, e.g., GNSS receivers. Since ionospheric delay has a high spatial correlation, ionosphere map coverage can be extended using spatial extrapolation methods. This paper proposes a support vector machine (SVM) to extrapolate the ionosphere map data with solar and geomagnetic parameters. One year of IGS ionospheric delay map data over South Korea is used to train the SVM algorithm. Subsequently, 1 month of ionospheric delay data outside the input data region is estimated. In addition to solar and geomagnetic environmental parameters, the ionospheric delay data from the inner data region are used to estimate the ionospheric delay data for the outside region. The accuracy evaluation is performed at three levels of range −5, 10, and 15∘ outside the inner data regions. The extrapolation errors are 0.33 TECU (total electron content unit) for the 5∘ region and 1.95 TECU for the 15∘ region. These values are substantially lower than the GPS Klobuchar model error values. Comparison with another machine learning extrapolation method, the neural network, shows a substantial improvement of up to 26.7 %.
Comparative performance analysis of 2DOF state feedback controller for automatic generation control using whale optimization algorithm

This paper presents the design of two‐degree‐of‐freedom state feedback controller (2DOFSFC) for automatic generation control problem. A recently developed new metaheuristic algorithm called whale optimization algorithm is employed to optimize the parameters of 2DOFSFC. The proposed 2DOFSFC is analyzed for a two‐area interconnected thermal power system including governor dead band nonlinearity and further extended to multiunit hydrothermal power system. The supremacy of the 2DOFSFC is established comparing with proportional‐integral, proportional‐integral‐derivative (PID), and 2DOFPID controllers optimized with different competitive algorithms for the concerned system. The sensitivity analysis of the optimal 2DOFSFC is performed with uncertainty condition made by varying bias coefficient B and regulation R parameters. Furthermore, the proposed controller is also verified against random load variations and step load perturbation at different locations of the system.
Study on high performance of a ship propulsion device by using the Weis-Fogh mechanism

Paper No.18-00105 © 2018 The Japan Society of Mechanical Engineers [DOI: 10.1299/jfst.2018jfst0016] Abstract The purpose of this study is to develop a high performance propulsive mechanism with high efficiency at high sailing speed by using a mechanism of rotary reciprocating wing motion based on the two-dimensional WeisFogh model. The sailing tests by both towing the model ship and its self-propulsion were carried out. In the towing test, the thrust of the model ship, the drag acting on the wing, and the wing opening angle in motion were measured for various parameters such as the wing moving speed and the sailing speed of the model ship. On the other hand, in the self-propulsion test the sailing speed of the model ship was measured for various frequency of wing reciprocating motion. The following results were obtained. The change of the wing opening angle in the mechanism of rotary reciprocating wing motion is obviously different from that of the wing opening angle in the mechanism of linear reciprocating wing motion. It was confirmed that the former is effective for the speeding up of the wing motion in comparison with the latter.
Overnight GLP-1 normalizes fasting but not daytime plasma glucose levels in NIDDM patients

GLP-1 (7-36 amide) normalizes fasting plasma glucose in NIDDM patients. lt was the aim to study the effect of overnight intravenous GLP-1 (7-36 amide) on the following 24 h-glucose profiles. Ten NTDDM patients (7 female, 3 male; age 62 ± 4 y., BM! (Body-Mass-Index) 29.6 ± 3.9 kg/rn2, duration 10 ± 7 y. , HbA1 10.9 ± 1.3% (normal 4.0-6.1%), treated with glibenclarnide and/or metformin) were studied on two occasions in random order: Either GLP-1 (7-36 amide) (Saxon Biochemicals, Hannover, FRG, 1 pmo! . kg . rnin') or placebo (0.9% NaCI with l% human serum albumin, Behringwerke, Marburg, FRG) were infused intravenously from 2200 to 700 (9 h) and plasma glucose profiles were obtained during the GLP-1 infusion and the following 24 hours. GLP-1 (7-36 amide)
Spiking activity in the visual thalamus is coupled to pupil dynamics across temporal scales

The processing of sensory information, even at early processing stages, is influenced by the internal state of the animal. Internal states, such as arousal, are often characterized by relating neural activity to a single “level” of arousal, defined by a behavioral indicator such as pupil size. In this study, we expand the understanding of arousal-related modulations in sensory systems by uncovering multiple timescales of pupil dynamics and their relationship to neural activity. Specifically, we observed coupling between spiking activity in the mouse dorsal lateral geniculate nucleus (dLGN) of the thalamus and pupil dynamics across timescales spanning three orders of magnitude, from seconds to minutes. Throughout all of these timescales, two distinct spiking patterns – tonic spikes and bursts – preferred opposing phases of pupil dynamics. This multi-scale coupling captures modulations distinct from those captured by pupil size per se, transitions between locomotion and quiescence, or saccadic eye movements. Furthermore, coupling persisted even during viewing of a naturalistic movie, where it contributed to differences in how visual information was encoded. We conclude that dLGN spiking activity is influenced by arousal processes associated with pupil dynamics occurring simultaneously across a broad range of timescales, with implications for the transfer of sensory information to the cortex.
Agressividade Tributária e Cash Holdings: um Estudo das Companhias Abertas Brasileiras

Esta pesquisa analisa a relação entre o grau de agressividade tributária e o nível de caixa apresentado no balanço das empresas brasileiras, listadas na BM&FBovespa, no período de 2010 a 2015, tendo por objetivo identificar se as empresas mais agressivas em termos tributários estão mais propensas a manter um nível maior de caixa. Os resultados desta pesquisa sugerem que em média esta amostra apresenta o equivalente em caixa em torno de 14,8% do ativo total da empresa. A medida de agressividade tributária utilizada foi a taxa efetiva de tributação de longo prazo (Effective Tax Rate – ETR). A ETR apresentou um índice médio de 23,2% demonstrando que as empresas desta amostra são consideradas agressivas tributariamente. Os resultados encontrados sugerem que a ETR possui significativa correlação com o nível de caixa e apresentou sinal positivo em seu coeficiente, evidenciando que as empresas menos agressivas, ou seja, com maiores índices de ETR, tendem a aumentar suas disponibilidades em caixa. Comportamento diferente do que aponta a pesquisa americana de Hanlon, Maydew e Saavedra (2014), que serviu como base para este estudo. Para os referidos autores as empresas com menor índice de ETR apresentam um caixa maior se comparado as empresas menos agressivas.
Natural transverse vibrations of helical springs in sections covered with elastic coatings

Manuscript submitted 2017-03-29, revised 2017-04-14, initially accepted for publication 2017-04-19, published in December 2017. Abstract. It has been demonstrated in previous studies that local elastomer coatings covering the end coils of helical springs can efficiently reduce the amplitudes of circum-resonant vibrations in such springs. The analysis of the influence that elastic coatings have on the frequencies and modes of natural transverse vibrations of springs is presented in this paper. The concept of the equivalent beam of the Timoshenko type is utilized in calculations of the frequencies and modes of transverse vibrations. The model developed allows users to determine the frequencies and modes of symmetric as well as antisymmetric vibrations of axially loaded springs with elastic coatings of arbitrary length. A comparison of the results obtained using FEM analysis, in which the model represented the actual spring geometry, with the results obtained by means of the presented model indicates its high accuracy.
The spatial -Fleming-Viot process on a large torus: genealogies in the presence of recombination

We extend the spatial �-Fleming-Viot process introduced in [BEV10] to incorporate recombination. The process models allele frequencies in a population which is distributed over the two-dimensional torus T(L) of sidelength L and is subject to two kinds of reproduction events : small events of radius O(1) and much rarer large events of radius O(L � ) for some α ∈ (0,1]. We investigate the correlation between the times to the most recent common ancestor of alleles at two linked loci for a sample of size two from the population. These individuals are initially sampled from ‘far apart’ on the torus. As L tends to infinity, depending on the frequency of the large events, the recombination rate and the initial distance between the two individuals sampled, we obtain either a complete decorrelation of the coalescence times at the two loci, or a sharp transition between a first period of complete correlation and a subsequent period during which the remaining times needed to reach the most recent common ancestor at each locus are independent. We use our computations to derive approximate probabilities of identity by descent as a function of the separation at which the two individuals are sampled.
Proportional–Integral Extremum Seeking for Vapor Compression Systems

In this paper, we optimize vapor compression system (VCS) power consumption through the application of a novel proportional–integral extremum-seeking controller (PI-ESC) that converges at the same timescale as the process. This extremum-seeking method uses time-varying parameter estimation to determine the local gradient in the map from manipulated inputs to performance output. Additionally, the extremum-seeking control law includes terms proportional to the estimated gradient, which requires subsequent modification of the estimation routine in order to avoid bias. The PI-ESC algorithm is derived and compared to other methods on a benchmark example that demonstrates the improved convergence rate of PI-ESC. PI-ESC is applied to the problem of compressor discharge temperature setpoint selection for a VCS such that power consumption is driven to a minimum. A physics-based simulation model of the VCS is used to demonstrate that with PI-ESC, convergence to the optimal operating point occurs faster than the bandwidth of typical disturbances—enabling application of extremum-seeking control to VCSs in environments under realistic operating conditions. Finally, experiments on a production room air conditioner installed in an adiabatic test facility validate the approach in the presence of significant noise and actuator and sensor quantization.
Robust Pre-Processing: A Robust Defense Method Against Adversary Attack

Deep learning algorithms and networks are vulnerable to perturbed inputs which are known as the adversarial attack. Many defense methodologies have been investigated to defend such adversarial attack. In this work, we propose a novel methodology to defend the existing powerful attack model. Such attack models have achieved record success against MNIST dataset to force it to miss-classify all of its inputs. Whereas Our proposed defense method robust pre-processing achieves the best accuracy among the current state of the art defenses. It consists of Tanh (hyperbolic tangent) function, smoothing and batch normalization to process the input data which will make it more robust over the adversarial attack. robust pre-processing improves the white box attack accuracy of MNIST from 94.3% to 98.7%. Even with increasing defense when others defenses completely fail, robust pre-processing remains one of the strongest ever reported. Another strength of our defense is that it eliminates the need for adversarial training as it can significantly increase the MNIST accuracy without adversarial training as well. This makes it a more generalized defense method with almost half training overhead and much-improved accuracy. robust pre-processing can also increase the inference accuracy in the face of the powerful attack on CIFAR-10 and SVHN data set as well without much sacrificing clean data accuracy.
A Modified Cartesian Factorized Back-Projection Algorithm for Highly Squint Spotlight Synthetic Aperture Radar Imaging

Highly squint synthetic aperture radar (SAR) increases the flexibility and aspect-information of observation but poses several challenges to frequency-domain algorithms. The back-projection (BP) algorithm is recognized to produce the best results for highly squint mode but at high computational expense. Several fast BP algorithms have been developed to enhance the efficiency of the BP integral. The Cartesian factorized BP (CFBP) algorithm has been proposed to improve the performance. However, CFBP is ineffective in the highly squint case because its range model (RM) is imprecise. In this letter, we propose a modified CFBP (MCFBP) algorithm for highly squint spotlight SAR imaging. We employ a transformed Cartesian coordinate system to treat the transceiver mode as approximately side-looking mode. According to the transformed coordinate system, we propose a modified RM (MRM) to reduce the range error. Based on the MRM, we derive modified image spectrum compression steps and the Nyquist sampling rate of the subaperture image. MCFBP inherits CFBP’s accuracy and efficiency advantages. Results of simulations and experiments performed by the X-band airborne SAR system with a maximum bandwidth of 1.2 GHz validate the improved performance of the proposed algorithm relative to BP and fast factorized BP.
On dealing with spatially correlated residuals in remote sensing and GIS

Key assumptions in standard regression models are that the residuals are independent and identically distributed. These assumptions are often not met in practice. In particular, the issue of spatial correlation amongst the residuals has had limited attention in the remote sensing and GIS literature. This paper discusses approaches that use familiar authorized models to specify the covariance amongst the residuals. The model parameters were estimated using a maximum likelihood approach (ML or REML). The accuracy of the approach was investigated using simulated data and found to give accurate estimates of the error variance (σ), although estimates of and range (a) and nugget component (s) were less accurate. The approach was found to be robust to choice of covariance function (exponential or spherical). The approach was then extended to deal with heteroskedastic residuals by incorporating a weighting component analogous to that used in weighted least squares. This was also shown to yield accurate results for σ, a and s. Finally, possibilities for extending these approaches to prediction are considered.
Generalized Maxwell model for micro-cracked viscoelastic materials

This paper aims to model the effective viscoelastic properties of micro-cracked materials based on the homogenization micro-macro approach. The isotropic case with random orientation and parallel distribution of micro-cracks in Burger and generalized Kelvin non-ageing linear viscoelastic solids was recently considered. To complete these works, this paper develops a model to estimate viscoelastic properties of materials that are constituted of two phases: a non-cracked phase described by Generalized Maxwell model and micro-cracks. The methodology consists in an approximation by using the same Generalized Maxwell model of the non-cracked phase for the overall cracked material. The crucial advantage of this technique is to avoid the complexity of the inverse Laplace–Carson (LC) transform. The approximation is carried out in short- and long-term behaviors in the LC space and validated in transient situation with exact solution obtained from the inverse LC transform in simple loading condition. Useful explicit formulas are provided for calculation of effective viscoelastic properties of isotropic micro-cracked media.
Acoustical design of the ELA4 launch pad for the Ariane 6 launcher

A new launch pad, ELA4, is going to be built in Kourou (French Guyana) for the future launcher Ariane 6. As the A64 version of the launcher will be more powerful at lift-off than Ariane 5, the exhaust ducts and the water injection systems have to be carefully designed, in order to be as effective as possible, and to reduce the acoustics on the payloads and the launcher. This has been done using the experience acquired and Ariane 5 and VEGA launch pads, as well as the understanding of the complex phenomena obtained by research activities. The general design have been validated and optimized by subscale test campaigns at the MARTEL test bench. Numerous configurations and parameters have been tested, including the geometry of the ducts and the launch table, the altitude of the launcher, the position and the mass flow rate and the spray type of the water injection systems. [These works have been done in collaboration between ESA, CNES, ASL, ONERA and PPRIME. ]
Assessing Aircraft Security: A Comprehensive Survey and Methodology for Evaluation

The sophistication and complexity of cyber attacks and the variety of targeted platforms have grown in recent years. Adversaries are targeting a wide range of platforms, e.g., enterprise networks, mobile phones, PCs, and industrial control systems. The past few years have also seen various cyber attacks on transportation systems, including attacks on ports, trains, airports, and aircraft. Due to the enormous potential damage inherent in attacking vehicles carrying many passengers and the lack of security measures applied in existing airborne systems, the vulnerability of aircraft systems is one of the most concerning topics in the vehicle security domain. This article provides a comprehensive review of aircraft systems and components and their various networks, emphasizing the cyber threats they are exposed to and the impact of a cyber attack on these components and networks and an aircraft’s essential capabilities. In addition, we present a comprehensive and in-depth taxonomy that standardizes the knowledge and understanding of cyber security in the avionics field. The taxonomy divides attack techniques into relevant categories (tactics) reflecting the various phases of the adversarial attack lifecycle and maps existing attacks according to the MITRE ATT&CK methodology. To contribute to increased understanding of the potential risks, we categorize the identified threats related to the various systems based on STRIDE threat model and demonstrate the practical application of this taxonomy in the analysis of real-world attack use cases. Finally, we review various mitigation techniques aimed at addressing security risks related to aircraft systems. Future work directions are presented as guidelines for industry and academia.
The Dirac-Higgs bundle

The Dirac–Higgs Bundle Jakob Lindblad Blaavand Balliol College A thesis submitted for the degree of Doctor of Philosophy, July 2015 The Dirac–Higgs bundle is a vector bundle with a natural connection on the moduli space of stable Higgs bundles on a compact Riemann surface. It is a vector bundle of null-spaces of a Dirac-operator coupled to stable Higgs bundles. In this thesis, we study various aspects of this bundle and its natural connection. The Dirac–Higgs bundle is hyperholomorphic on the smooth hyperkähler moduli space of stable Higgs bundles. This property is a generalisation of the four-dimensional antiself-duality equations to hyperkähler manifolds. One use of the Dirac–Higgs bundle is the construction of a Nahm transform for Higgs bundles. This transform produces hyperholomorphic bundles on the moduli space of rank one Higgs bundles. The Higgs bundle moduli space is non-compact and we study the asymptotics of the connection in the Nahm transform of a Higgs bundle. We show that elements of the nullspaces concentrate at a finite number of points on the Riemann surface. This asymptotical behaviour naturally defines a frame for the Nahm transform, which is conjectured to be asymptotically unitary. By considering only the holomorphic structure, the Nahm transform of a Higgs bundle extends to a holomorphic bundle on the natural compactification of the rank one Higgs bundle moduli space. We discuss various aspects of this extended holomorphic bundle. Most importantly, it is a sheaf extension in which the constituent sheaves and the extension class have natural interpretations in terms of the original Higgs bundle. Furthermore, the extended bundle is not fixed at the divisor at infinity; explicit examples show that it depends on the type of Riemann surface, for example. The Dirac–Higgs bundle has a parabolic cousin. In the parabolic case the rank depends on the number of marked points and the total multiplicity of the zero weights in the parabolic structure. The moduli space of stable rank two parabolic Higgs bundles on the Riemann sphere with four marked points has complex dimension two. Furthermore, there is a combination of parabolic weights such that the Dirac–Higgs bundle is a line bundle with an instanton connection. We study the topology of this line bundle and find that the instanton does not have finite energy. As in the non-parabolic case we define a Nahm transform for parabolic Higgs bundles, and in the case of genus one Riemann surfaces use it to produce doubly-periodic instantons of finite energy.