Miracle-dz/UniFAR-FTUs huggingface dataset:
Coherent Detection Algorithm for Radar Maneuvering Targets Based on Discrete Polynomial-Phase Transform

Radar detection of maneuvering targets with high velocity and acceleration often results in severely deteriorative performance or even failure. Parameter-search approaches are commonly used to overcome such difficulty, but the substantial computational load involved makes them unable to meet the real-time requirements of practical systems. In this paper, to improve the detection performance for maneuvering targets at no expense of computing resource, we derive a coherent detection algorithm for maneuvering targets based on the discrete polynomial-phase transform. The proposed algorithm simultaneously decouples the displacement and velocity of target and reduces the order of the acceleration-induced quadratic phase in the frequency domain of the pulse compressed echoes. As such, the range and Doppler walks are both compensated without any a priori knowledge. In addition, the impact of the cross terms on the detection of auto-terms is investigated in the multiple targets scenario, and the applicable conditions of the proposed algorithm are given. Using numerical simulation and real-data experiments, we demonstrate the advantages of the proposed algorithm over state-of-the-art methods in terms of integration gain and estimation accuracy.
The effect of aspect ratio on the wake structure of finite wall-mounted square cylinders

This paper presents a combined experimental and large-eddy simulation study to characterise the effect of aspect ratio on the near-wake structure of a square finite wall-mounted cylinder (FWMC). The cylinder aspect ratios (span $L$ to width $W$ ) investigated in the experiments were $1.4\leqslant L/W\leqslant 21.4$ and the oncoming boundary-layer thicknesses were $1.3W$ and $0.9W$ at a Reynolds number based on cylinder width of $1.4\times 10^{4}$ and $1.1\times 10^{4}$ , respectively. In complementary simulations, the cylinder aspect ratios investigated were 1.4, 4.3, 10 and 18.6. The cylinder wake structure was visualised in three-dimensional space using a vortex core detection method and decomposed to its oscillation modes using the spectral proper orthogonal decomposition (SPOD) technique. A parametric diagram is proposed to predict whether the time-averaged wake structure is a dipole or a quadrupole pattern, based on oncoming boundary-layer height and aspect ratio. Cellular shedding occurs when the aspect ratio is high with up to three shedding cells occurring across the span for aspect ratios $L/W>18$ . Each of these cells sheds at a distinct frequency, as evidenced by the spectral content of the surface pressure measured on the side face and the near-wake velocity. Amplitude modulation is also observed in the vortex shedding, which explains the amplitude modulation of the acoustic pressure emitted by square FWMCs. SPOD is shown to be a viable method to identify the occurrence of cellular shedding in the wake.
Nonlinear disturbance observer-based control for a class of discrete-time stochastic systems with multiple heterogenous disturbances

In this paper, the nonlinear disturbance observer-based control (NDOBC) scheme is proposed for a class of discrete-time stochastic systems with multiple heterogenous disturbances, which include the non-harmonic disturbance and a sequence of random vectors. A nonlinear disturbance observer (NDO) is designed to estimate the non-harmonic disturbance, then the NDOBC scheme is proposed by combining DOBC with H ∞ control, such that the composite system can achieves asymptotically mean-square bounded and asymptotically mean-square stable in different conditions. Finally, simulation results show the effectiveness of the proposed method.
Iterative feedback tuning for Hamiltonian systems based on variational symmetry

This paper proposes a novel iterative feedback tuning (IFT) for Hamiltonian systems, which can describe a practically important class of nonlinear systems. Hamiltonian systems have a special property called variational symmetry, and it can be used to estimate the input‐output mapping of the variational adjoint for certain input‐output mappings of the systems. First, we derive a modified variational symmetry to adapt to the gradient estimation of an optimal control–type cost function with respect to adjustable parameters of a controller. Second, we provide an IFT algorithm based on the property, which generates the optimal parameters minimizing the cost function by iteration of experiments. The proposed algorithm requires less number of experiments to estimate the gradient than the conventional IFT methods for nonlinear systems. We also provide a method to optimize the elements of the dissipation matrix, which does not directly appear in the Hamiltonian function, by equipping a dynamic feedback of the generalized coordinate. Moreover, we provide an IFT algorithm considering parameter constraints so that the parameters can be optimized within a prescribed search range. Finally, a numerical simulation of a two‐link robot manipulator including a comparison with the conventional IFT methods demonstrates the effectiveness of the proposed method.
Giant Enhancement of Nonlinear Optical Processes With Split-Ring Resonators for THz Applications

Plasmonic resonances have been widely applied in nonlinear optics due to their unprecedented capability of concentrating and manipulating light at the deep subwavelength scale. Doubly resonant cavities can confine light of different wavelengths in the same cavity with large modal overlap and strong field enhancement. However, designing of such cavities is usually difficult when the resonant wavelengths differ by orders of magnitude. Here, by using plasmonics to match the modal sizes, we propose a split-ring resonator that resonates in both the near-infrared and terahertz (THz) bands simultaneously, with their fields colocalized within a deep subwavelength gap to achieve strong nonlinear interactions. THz wave generation through difference-frequency generation can be significantly enhanced in this resonator, yielding a 4-order-of-magnitude enhancement of the effective nonlinear susceptibility from the material’s intrinsic value. Therefore, such structures can serve as an ideal platform for nonlinear optical processes between the near-infrared and THz waves, which can be employed for THz applications such as THz wave generation and detection.
Parameterized Resiliency Problems ∗

We introduce an extension of decision problems called resiliency problems . In a resiliency problem, the goal is to decide whether an instance remains positive after any (appropriately deﬁned) perturbation has been applied to it. To tackle these kinds of problems, some of which might be of practical interest, we introduce a notion of resiliency for Integer Linear Programs (ILP) and show how to use a result of Eisenbrand and Shmonin (Math. Oper. Res., 2008) on Parametric Linear Programming to prove that ILP Resiliency is ﬁxed-parameter tractable (FPT) under a certain parameterization. Todemonstrate the utility of our result, we consider natural resiliency variants of several concrete problems, and prove that they are FPT under natural parameterizations. Our ﬁrst results concern a four-variate problem which generalizes the Disjoint Set Cover problem and which is of interest in access control. We obtain a complete parameterized complexity classiﬁcation for every possible combination of the parameters. Then, we introduce and study a resiliency variant of the Closest String problem, for which we extend an FPT result of Gramm et al. (Algorithmica, 2003). We also consider problems in the ﬁelds of scheduling and social choice. We believe that many other problems can be tackled by our framework.
On BMRN*-colouring of planar digraphs

International audience In a recent work, Bensmail, Blanc, Cohen, Havet and Rocha, motivated by applications for TDMA scheduling problems, have introduced the notion of BMRN*-colouring of digraphs, which is a type of arc-colouring with particular colouring constraints. In particular, they gave a special focus to planar digraphs. They notably proved that every planar digraph can be 8-BMRN*-coloured, while there exist planar digraphs for which 7 colours are needed in a BMRN*-colouring. They also proved that the problem of deciding whether a planar digraph can be 3-BMRN*-coloured is NP-hard. In this work, we pursue these investigations on planar digraphs, in particular by answering some of the questions left open by the authors in that seminal work. We exhibit planar digraphs needing 8 colours to be BMRN*-coloured, thus showing that the upper bound of Bensmail, Blanc, Cohen, Havet and Rocha cannot be decreased in general. We also generalize their complexity result by showing that the problem of deciding whether a planar digraph can be k-BMRN*-coloured is NP-hard for every k ∈ {3,. ,6}. Finally, we investigate the connection between the girth of a planar digraphs and the least number of colours in its BMRN*-colourings.
Matrix estimation using shrinkage of singular values with applications to signal denoising

This thesis documents investigations on developing the better spectral shrinkage functions for matrix estimation. It proposes two effective spectral shrinkage estimators. The first estimator exploits the correlation present in the data matrix by decoupling the shrinkage and the truncation of singular values. It employs a logistic function based shrinkage of singular values and shows better rank estimation than the existing methods. The parameters of this estimator are tuned by grid-search solution of a SURE formulation. However, the method is computationally expensive and the applicability of this estimator is limited. The second estimator addresses this problem. It expresses the thresholding function as a linear combination of the derivatives of a Gaussian so that the corresponding SURE admits a closed form solution for the optimal parameters of the shrinkage function. Hence, it avoids the huge computational cost involved in the first method in parameter search. In addition, this linearization of thresholding function allows to increase the number of parameters arbitrarily, providing a sufficient flexibility in the shape of the shrinkage function. The estimator performs better matrix estimation than the state-of-the art methods. The thesis further investigates the effectiveness of the proposed estimators in signal denoising applications in a collaborative filtering framework. In this framework, the noisy signals under investigation are rearranged in the form of several data matrices. The denoising of electrocardiogram (ECG) signal is presented as the first application. For this purpose, the data matrices are formed by grouping similar blocks from the noisy ECG signal. These data matrices are then denoised by the proposed matrix estimation methods. The denoised signal is obtained by inverse operation of the matrix formation. The quality of the denoised signal is measured
Nonlinear Dynamic Analysis of an Electrostatically Actuated Cylindrical Micro-Beam Subjected to Cross Fluid Flow

This work investigates the nonlinear dynamic behavior of an electrostatically actuated clamped–clamped cylindrical micro-beam subjected to vortex induced vibrations (VIV). Lift and drag forces are the two basic flow-induced factors affecting the dynamics of the micro-beam under fluid flow which are neglected in micro-structures immersed in stationary fluids. The electrostatically actuated micro-beam is modelled using Timoshenko beam theory and the impact of the fluid cross-flow is accounted for by considering its resultant force elements comprising inertia, lift and drag force vectors. In addition, the size dependency effect on the nonlinear dynamics of the micro-beam is studied based on the Modified Couple Stress Theory (MCST). The governing nonlinear equations are solved using the Galerkin and step-by-step linearization method to evaluate the response of the coupled structure to a combined voltage excitation plus fluid flow. Response of the micro-beam to different input voltages in the presence of fluid velocities are investigated and it is shown that the range and intensity of the lock-in regime is effectively controlled by the input voltage and fluid-to-beam density ratio.
EFEKTIVITAS PELAKSANAAN METODE DISKUSI KELOMPOK TERPUSAT (FOCUS GROUP DISCUSSION)TERHADAP MOTIVASI BELAJAR IPS MURID KELAS V SD NEGERI II BONE-BONE KOTA BAUBAU

Abstrak : Pembelajaran yang terlaksana di sekolah dasar, khususnya pada proses pembelajaran IPS pada proses transfer terjadi guru hanya terpusat pada buku dan tidak menggunakan berbagai metode dalam pembelajaran, murid hanya berperan sebagai pendengar dan pencatat, guru kurang memberi kesempatan kepada murid untuk mengemukakan pendapatnya, sehingga didalam proses pembelajaran murid hanya terkesan diam dan tidak berperan aktif didalam kegiatan belajar mengajar, hal ini menyebabkan kurangnya motivasi murid dalam belajar. Sehingga metode FGD menjadi alternatif untuk memotivasi murid dalam belajar khususnya pada pembelajaran IPS. FGD sebagai bentuk diskusi yang menggali lebih dalam pemahaman murid terhadap suatu topik pembelajaran yang dipelajari yang dapat menarik perhatian murid sehingga dapat memotivasi mereka dalam proses pembelajaran. Jenis penelitian ini adalah penelitian eksperimen dengan desain True Eksperimental Design adalah penelitian yang benar-benar untuk melihat hubungan sebab-akibat”. Peneliti menggunakan ekperimen dikarenakan ingin memanipulasi variabel dengan memberikan perlakuan. Penelitian ini bertujuan untuk mengetahui efektivitas pelaksanaan metode FGD terhadap motivasi belajar IPS murid kelas V SDN II Bone-bone Kota Baubau. Hasil penelitian nantinya diharapkan menjadi acuan atau referensi bagi yang akan melakukan penelitian berikutnya, serta dijadikan sebagai metode pembelajaran di sekolah. Kata kunci : Metode FGD, Motivasi Belajar.
A Comparative Study on the Performance of Marine Magnetohydrodynamic Motors With Helical and Linear Channels

A magnetohydrodynamic (MHD) thruster is a type of electric motors which moves electrically conductive fluids without any mechanical moving parts. In this study, a linear-type MHD thruster is compared with a helical-type MHD thruster that has the same channel length and volume. For this purpose, two analytical models are used to predict the behaviors of these two types of marine MHD thrusters. The analytical model used for the helical thruster is validated by comparison to the experimental data obtained by other researchers. To validate the analytical model used for the linear thruster, a thruster prototype is manufactured and tested. The results show that although the solenoid magnet of the helical-type thruster is much easier to get a higher magnetic flux density than the saddle-shaped magnet of the linear-type thruster, the efficiency and propulsion force density of the linear-type thruster are much better than those of the helical-type one. Therefore, the linear-type thrusters cannot be ignored simply because of the complexity of their coils.
Mathematical models in cancer risk assessment.

Standardized long-term carcinogenicity tests aim to reveal the relationship between exposure to a chemical and occurrence of a carcinogenic response. The analysis of such tests may be facilitated by the use of mathematical models. To what extent current models actually achieve this purpose is difficult to evaluate. Various aspects of chemically induced carcinogenesis are treated by different modeling approaches, which proceed very much in isolation of each other. With this Chapter we aim to provide for the nonmathematician a comprehensive and critical overview of models dealing with processes involved in chemical carcinogenesis. We cover the entire process of carcinogenesis, from exposure to effect. We succinctly summarize the biology underlying the models and emphasize the relationship between model assumptions and model formulations. The use of mathematics is restricted as far as possible with some additional information relegated to tables.
PARA: experimental device for virtual and augmented reality

The device we are presenting is a patented HMD with a custom stereo camera mounted on the front side. With a 110°field of view for both augmented and virtual realities, we perform live software-based distortions using diﬀerent methods for the HMD and cameras lenses for real-time rendering and the lowest photon-to-pixel time. The reality and the virtual space are properly aligned thanks to real-time distortion methods. The device is also fully autonomous and can track its translation and rotation in known and unknown environments thanks to Simultaneous Location and Mapping with the cameras, having the option to perform dense 3D reconstruction.
S-Shaped Current–Voltage Characteristics in Solar Cells: A Review

S-shaped current–voltage (<italic>I</italic>–<italic>V</italic>) characteristics are a frequently occurring hurdle in the development of new solar cell material combinations and device architectures. Their presence points to the existence of a charge transport bottleneck that needs to be removed in order to unlock high fill factors and power conversion efficiencies. In this review, examples of studies in which s-shaped <italic>I</italic>–<italic>V</italic> curves have appeared are presented, and the cause and mitigation are discussed. Different solar cell material systems are often treated by separate communities, thereby, also the physics of s-shaped <italic>I</italic>–<italic>V</italic> curves have been treated separately. This review covers the main solar cell technologies—silicon, thin film, organic, hybrid—with the aim to provide an overarching picture of the common mechanisms and universal guidelines for mitigation of s-shaped <italic>I</italic>–<italic>V</italic> characteristics in emerging solar cell technologies. Except for a few studies on organic solar cells, s-shaped <italic>I</italic>–<italic>V</italic> curves are reported to result from charge transport barriers at one of the (selective) contact layers that can be overcome by interface engineering and doping.
Diffusional Glueing in Solutions of the Periodically Forced Fitzhugh-Nagumo Equations

equations are widely used in medicine,physiology,chemistry and other elds in the form of two-coupled partial differential equations for activator and inhibitor variables.In this an extended FHN model ,which considers diffusion and external periodic forcing. In this work we discovered an phenomenon:the diffusion acts as a glue. The glue combines multiple waves and turns them into a uniform structure. The presented. ABSTRACT
Unsupervised Change Detection Based on a Unified Framework for Weighted Collaborative Representation With RDDL and Fuzzy Clustering

In this paper, we propose a novel unsupervised change detection method of remote sensing (RS) images based on a unified framework for weighted collaborative representation (WCR) with robust deep dictionary learning (RDDL) and fuzzy clustering. Specifically, WCR is employed to collaboratively represent neighborhood features with lower computational complexity, for which the RDDL model is built to learn more effective and representative overcomplete dictionary and enhance the robustness against the noise and outliers. Meanwhile, in order to make the resulting collaborative coefficients more beneficial for clustering, the unified framework for WCR with RDDL and fuzzy clustering is designed. By doing so, our framework not only precludes the utilization of third-party clustering algorithm, but also achieves better detection performance. Subsequently, the spatial constraint is enforced on the membership matrix to yield the updated one for further improving the accuracy of change detection. Finally, a binary change mask (CM) is achieved by assigning the pixels into the changed and unchanged classes. Experiments are performed on five pairs of RS images, and experimental results demonstrate the effectiveness of the proposed method.
Statistics, plumes and azimuthally travelling waves in ultimate Taylor–Couette turbulent vortices

In this paper, we experimentally study the influence of large-scale Taylor rolls on the small-scale statistics and the flow organization in fully turbulent Taylor–Couette flow for Reynolds numbers up to $Re_{S}=3\times 10^{5}$ . The velocity field in the gap confined by coaxial and independently rotating cylinders at a radius ratio of $\unicode[STIX]{x1D702}=0.714$ is measured using planar particle image velocimetry in horizontal planes at different cylinder heights. Flow regions with and without prominent Taylor vortices are compared. We show that the local angular momentum transport (expressed in terms of a Nusselt number) mainly takes place in the regions of the vortex in- and outflow, where the radial and azimuthal velocity components are highly correlated. The efficient momentum transfer is reflected in intermittent bursts, which becomes visible in the exponential tails of the probability density functions of the local Nusselt number. In addition, by calculating azimuthal energy co-spectra, small-scale plumes are revealed to be the underlying structure of these bursts. These flow features are very similar to the one observed in Rayleigh–Bénard convection, which emphasizes the analogies of these systems. By performing a complex proper orthogonal decomposition, we remarkably detect azimuthally travelling waves superimposed on the turbulent Taylor vortices, not only in the classical but also in the ultimate regime. This very large-scale flow pattern, which is most pronounced at the axial location of the vortex centre, is similar to the well-known wavy Taylor vortex flow, which has comparable wave speeds, but much larger azimuthal wavenumbers.
Robust Restoration of Sparse Multidimensional Single-Photon LiDAR Images

The challenges of real world applications of the laser detection and ranging (Lidar) three-dimensional (3-D) imaging require specialized algorithms. In this paper, a new reconstruction algorithm for single-photon 3-D Lidar images is presented that can deal with multiple tasks. For example, when the return signal contains multiple peaks due to imaging semitransparent surfaces, or when imaging through obscurants such as scattering media. A generalization to the multidimensional case, including multispectral and multitemporal 3-D images, is also provided. The approach is based on the minimization of a cost function accounting for Poissonian observations of the single-photon data, the nonlocal spatial correlations between pixels and the small number of depth layers inside the observed range window. An alternating direction method of multipliers that offers good convergence properties is used to solve this minimization problem. The resulting algorithm is validated on synthetic and real data and in challenging realistic scenarios including sparse photon regimes for fast imaging, the presence of high background due to obscurants, and the joint processing of multispectral and/or multitemporal data.
GE_GRAVITY: Stata module to solve a simple general equilibrium one sector Armington-CES trade model

ge_gravity solves for general equilibrium effects of changes in trade policies using a one sector Armington-CES trade model. It uses a simple fixed point algorithm that allows for fast computation. This approach, together with the implementation in Stata, make this program ideal for bootstrapping confidence intervals for general equilibrium simulations based on prior gravity estimates of FTAs or other similar variables. Examples of references which conduct general equilibrium analysis based on FTA estimates in this way include Egger, Larch, Staub, & Winkelmann (2011), Anderson & Yotov (2016), and Baier, Yotov, & Zylkin (2019). Yotov, Piermartini, Monteiro, & Larch (2016) provide a detailed survey and introduction to the topic.