Miracle-dz/UniFAR-FTUs huggingface dataset:
Respiratory motion of the heart: Implications for magnetic resonance coronary angiography

Magnetic resonance(MR) coronary imaging is susceptible to artifacts caused by motion of the heart. The purpose of this thesis was to study the respiratory motion of the coronary arteries and to use the results to develop strategies for improved MRimaging. The first section of the thesis describes a MR motion correction technique for objects undergoing a 3D affine transformation. The remainder of the thesis focuses on measuring the respiratory motion of the heart from free breathing x-ray angiograms. Stereo reconstruction methods are used to generate 3D models of the arteries from biplane angiograms. A method for tracking the motion of the arteries in a sequence of biplane images is presented next. The algorithm uses 3D regularizing constraints on the length changes of the arteries and on the spatial regularity of their motion. The algorithm was validated using a deforming vascular phantom. RMS 3D distance errors were measured between centerline models tracked in the x-ray images and gold-standard models derived from a gated 3D MR acquisition. The mean error was 0.69±0.06 mm for four different orientations of the x-ray system. The motion field recovered from free breathing angiograms is a combination of the cardiac contraction and respiratory motion of the heart. A cardiac respiratory parametric model is formulated to decompose the field into independent cardiac and respiratory components. Results are presented for ten patients imaged during spontaneous tidal breathing. For all patients, the heart translated caudally (mean, 4.9±1.9 mm ) and rotated in a cranio-dorsal direction (mean, 1.5°±0.9°) during inspiration. In eight patients, the heart also translated anteriorly (mean, 1.3±1.8 mm ) and rotated in a caudo-dextral direction (mean, 1.2°±1.3°). Anatomic landmarks were used to compare results across patients. Three dimensional displacements and velocities were compared, and quiescent periods in the respiratory and cardiac cycles were measured. Finally, respiratory motion was analyzed using three linear motion models that correspond to available MR motion correction techniques: translation, rigid body, and affine. Calculations indicate that a two-to-four-fold increase in scan efficiency is attainable, resulting in reduced scan times while maintaining image quality.
Fractal image analysis - Application to the topography of Oregon and synthetic images.

The Earth’s topography generally obeys fractal statistics; after either one- or two-dimensional Fourier transforms the amplitudes have a power-law dependence on wave number. The slope gives the fractal dimension, and the unit wave-number amplitude is a measure of the roughness. In this study, digitized topography for the state of Oregon (∼7 points/km) has been used to obtain maps of fractal dimension and roughness amplitude. The roughness amplitude correlates well with variations in relief and is a promising parameter for the quantitative classification of landforms. The spatial variations in fractal dimension are low and show no clear correlation with different tectonic settings. For Oregon the mean fractal dimension from a two-dimensional spectral analysis is D = 2.586, and for a one-dimensional spectral analysis the mean fractal dimension is D = 1.487, which is close to the Brown noise value D = 1.5. Synthetic two-dimensional images have also been generated for a range of D values. For D = 2.6, the synthetic image has a mean one-dimensional spectral fractal dimension D = 1.58, which is consistent with our results for Oregon. This approach can be easily applied to any digitized image that obeys fractal statistics.
Dynamics of a classical hard-sphere gas. II. Numerical results

For pt.I see ibid., vol.15, p.2801 (1982). Numerical results for the correlation functions of density, transverse current and energy density of a classical hard-sphere fluid at high density are presented based on a mode-coupling theory developed in a previous paper. The results are compared with an approximate solution of generalised Enskog theory and with results of molecular dynamic experiments. The author finds propagating shear waves above a critical wavenumber and a slowly decaying density correlation function at intermediate wavenumbers, both new qualitative features being in agreement with molecular dynamic results.
Comparison properties of stochastic decision free Petri nets

Stochastic comparison problems arising in the analysis of stochastic decision free Petri nets are treated. The analysis is based on the evolution equations satisfied by firing times. Various structural properties are obtained, including the association of the firing times and their stochastic and convex monotonicity with respect to the holding time sequences, the initial marking, and the topology. The association and the stochastic monotonicity properties are extended to the counters using an inversion relation. It is also proven that the counters and the throughput are stochastically concave in the initial marking, provided that the holding times are independent, identically distributed, and belong to a subclass of the log-concave distribution functions that are introduced. Various bounds for the asymptotic cycle time and the throughput are then derived from these stochastic ordering results. Comparative results are presented for the marking and response times. >
On systems with non-Markovian regime changes

Jump models have been proposed for a wide variety of applications from fault-tolerant control to power network transient analysis and multitarget tracking. However, most available results are limited to Markovian transitions, which excludes systems with rates dependent on the time elapsed since the last transition; that is, typically, the burn-in and aging phenomena. A non-Markovian model is proposed and its use for the synthesis of feedback regulators is discussed. >
Homogenization in the Theory of Viscoplasticity

We study the homogenization of the quasistatic initial boundary value problem with internal variables which models the deformation behavior of viscoplastic bodies with a periodic microstructure. This problem is represented through a system of linear partial differential equations coupled with a nonlinear system of differential equations or inclusions. Recently it was shown by Alber [2] that the formally derived homogenized initial boundary value problem has a solution. From this solution we construct an asymptotic solution for the original problem and prove that the difference of the exact solution and the asymptotic solution tends to zero if the lengthscale of the microstructure goes to zero. The work is based on monotonicity properties of the differential equations or inclusions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Speaker identification made easy with pruned reassigned spectrograms

One common scenario for speaker identification presents the task of identifying samples of speech from members of a previously enrolled group. One recent (and typical) set of results used 36 s of speech from each speaker to train Gaussian models by expectation-maximization during enrollment, and 20 s of speech for the test samples. Three major problems with this procedure are (1) sensitivity to noise; (2) impractical amounts of speech are required; (3) computationally expensive training is required. In our study, the reassigned spectrogram is pruned using phase-derivative indicator functions to provide a sparse time-frequency matrix of very small (40 ms) samples of speech. The pruning eliminates Gaussian noise up to ~1 dB SNR. Principle components analysis provided a set of 30 features from each spectrogram. Using an enrolled group of 24 speakers recorded under low-fidelity conditions, 83% identification accuracy (comparable to state of the art results with 6 dB SNR) was achieved from real-time classification methods (e.g., support vector machines) without need for extensive training. Moreover, these results extend to 1 dB SNR where standard techniques break down. The three main problems of speaker identification can thus be better addressed by our methodology.
On the regularity of the magnetic field in a diffusive plasma

It is known that magnetic fields in ideal chaotic plasmas tend to become extremely irregular and to concentrate in a fractal set, and it is assumed that the presence of a positive resistivity will have a smoothing effect. Here we try to quantify this effect by proving new inequalities which, on the one hand, relate the local and global size of velocity and magnetic field with the gradient of this field, and on the other provide a bound of the area of generalized level surfaces.
Conference on Electronics , Telecommunications and Computers – CETC 2013 A New Testing Method for Hardware Trojan Detection

This paper presents a partitioning approach to improve the Trojan detection process. The proposed transition probability based method tries to partition combinational circuits for pseudo exhaustive testing. The nodes of digital circuit in which the transition probability is less than predefined threshold mark as the potential point for hardware Trojan insertion. Thus, our objective is new circuit partitioning method to increase the transition probability of the potential points. We propose I-PIFAN partitioning algorithm in which the optimal size of primary input cone (N) and Fan-out (F) values are selected to partition a given combinational circuit. The partitioning method determines the optimal values of N and F to increase the transition probability and minimize 1) the number of test vector, 2) the number of partitions and 3) the critical path delay. This work ensures that all nodes with low transition probability pass the threshold after partitioning. The proposed algorithm reduces the test time of digital combinational circuits and improves Trojan detection quality. The partitioning method is applied to the ISCAS’85 benchmark circuits and the simulation results show the test vectors reduction and improvement of transition probabilities. © 2014 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of ISEL – Instituto Superior de Engenharia de Lisboa.
Weak Nonlinear Long Waves in Channel Flow with Internal Dissipation

This article concerns the evolution of long waves (O(ε−1/2) wavelength) of small [O(ε)] amplitude in channel flow with internal dissipation. We use multiple scale expansions to derive a generalized Kuramoto–Sivashinsky (GKS) equation that governs the dominant asymptotic solution in the limit of small disturbances and marginal linear instability. We compare this solution with numerical integrations of the full quasilinear system, and show that the error is consistent with an asymptotic solution to ε3/2 over a time interval of order ε−3/2.
Astro-1 and ground-based observations of Markarian 335: Evidence for an accretion disk

Simultaneous UV and optical observations of the Seyfert galaxy Markarian 335 (z = 0.026) during the Astro-1 mission yield a spectrum spanning the wavelength range of 912-8410 A. In the sub-Ly alpha region a prominent blended emission feature of O VI lambda lambda 1032, 1038, and Ly beta is nearly as strong as C IV wavelength 1549. The continuum flux extends beyond the redshifted Luman limit without a noticeable discontinuity, but a siginificant change in slope exists near the redhsifted Lyman edge. We suggest that such a change may be the signature of a Lyman edge in an accretion disk seen at a small inclination angle. Using a disk model including such an edge, we fit the spectrum with a central black hole mass of 5 x 10(exp 7) solar mass, an accretion rate of 0.07 solar mass/yr, and an optical depth at the Lyman edge of 0.4. To account for the strong O VI emission as well as the soft X-ray excess, we consider the effects of Comptonization on the disk spectrum, which can produce a high-energy tail for the UV bump and also smooth the Lyman edge feature.
Optimization of Optical Components for Optical Computer Systems

We analyze several different methods of encoding and calculating optically thin periodic Fourier-transform binary phase gratings and multiple or continuous phase kinoforms for use as e.g. optical fan-out elements in all-optical computing systems. The construction of the gratings and kinoforms is equivalent to the phase retrieval problem which we formulate as a nonlinear optimization problem and solve using different numerical techniques. Typical gratings have very high diffraction efficiency (up to 95%) and high reconstruction accuracy.
Electrospinning of continuous aligned polymer fibers

Electrospinning is a technique employed for preparing polymer fibers having diameters in the range of 10 μm–10 nm using high electrostatic field. In this letter, we report the formation of aligned polymer fibers, several centimeters in length, with separation between the fibers in the range of 5–100 μm. Achieving alignment is an important step toward the exploitation of these fibers in applications. We have employed about 4500 V and a separation distance of about 1–3 cm between the electrodes. Smaller distance between electrodes, we believe, provides better control on the formation of the fibers.
Regularized iterative and noniterative procedures for object restoration in the presence of noise: an error analysis

An analysis is carried out, using the prolate spheroidal wave functions, of certain regularized iterative and noniterative methods previously proposed for the achievement of object restoration (or, equivalently, spectral extrapolation) from noisy image data. The ill-posedness inherent in the problem is treated by means of a regularization parameter, and the analysis shows explicitly how the deleterious effects of the noise are then contained. The error in the object estimate is also assessed, and it is shown that the optimal choice for the regularization parameter depends on the signal-to-noise ratio. Numerical examples are used to demonstrate the performance of both unregularized and regularized procedures and also to show how, in the unregularized case, artefacts can be generated from pure noise. Finally, the relative error in the estimate is calculated as a function of the degree of superresolution demanded for reconstruction problems characterized by low space–bandwidth products.
Long‐duration hectometric type III radio bursts and their association with solar energetic particle (SEP) events

It has recently been suggested by Cane et al. [2002] that a class of type III solar radio bursts, called type III‐l, is reliably associated with intense solar energetic particle (SEP) events. They proposed that the causative electrons for these bursts are accelerated in regions of reconnecting magnetic field in the wakes of coronal mass ejections (CMEs). In this paper, we examine the durations, intensities, and other characteristics of such radio bursts in the hectometric frequency range and compare them to several groups of control events. We conclude that simple criteria, based on hectometric data alone, can identify the majority (∼80%) of type III‐l radio bursts, which are associated with >20 MeV SEP proton events, while excluding almost 100% of the control events. Detailed study of these type III‐l bursts may play a significant role in a better understanding of the acceleration of SEPs and of the magnetic field evolution in the vicinity of CMEs.
The use of bowed reverse twist disclination lines for the measurement of long pitch lengths in chiral nematic liquid crystals

A novel method is described for the measurement of long pitch lengths in chiral nematic liquid crystals using the bowing of reverse twist disclination lines in 90° twisted nematic devices. The method has been used to measure pitch lengths of up to 50 mm, significantly longer than previously possible using existing methods. † The research was performed in part at the Department of Chemistry, The University of York, Heslington, York YO10 5DD, UK.
Multiphoton fluorescence spectra and lifetimes of biliverdins and their protein-associated complex

To investigate whether endogenous biliverdins can serve as a fluorescence metabolic marker in cancer diagnosis, we measured their multiphoton fluorescence spectra and lifetimes with femtosecond Cr:forsterite laser. Excited at 1230nm, the two-photon fluorescence of biliverdins peaks around 670nm. The corresponding lifetime (<100ps) was much shorter than those of porphyrins (~10ns), which is another commonly present metabolites in living cells. Further mixing biliverdins with proteins like fetal bovine serum (FBS), biliverdins reductase A (BVRA), or heme oxygenase-1 (HO-1), the yields of red autofluorescences didn't change a lot, but the corresponding lifetimes with HO-1 and BSA were lengthened to 200~300ps. This indicates that biliverdin can have an association with these proteins and change its lifetime. These spectral and temporal characteristics of fluorescence make biliverdin a potential marker fluorophore for hyperspectral diagnosis on the heme catabolism in human cells or tissues.
A kinetic energy reduction technique and characterizations of the ground states of spin-1 Bose-Einstein condensates

We justify some characterizations of the ground states of spin-1 Bose-Einstein condensates exhibited from numerical simulations. For ferromagnetic systems, we show the validity of the single-mode approximation (SMA). For an antiferromagnetic system with nonzero magnetization, we prove the vanishing of the $m_F=0$ component. In the end of the paper some remaining degenerate situations are also discussed. The proofs of the main results are all based on a simple observation, that a redistribution of masses among different components will reduce the kinetic energy.
Level set based robust shape and topology optimization under random field uncertainties

A robust shape and topology optimization (RSTO) approach with consideration of random field uncertainty in loading and material properties is developed in this work. The proposed approach integrates the state-of-the-art level set methods for shape and topology optimization and the latest research development in design under uncertainty. To characterize the high-dimensional random-field uncertainty with a reduced set of random variables, the Karhunen–Loeve expansion is employed. The univariate dimension-reduction (UDR) method combined with Gauss-type quadrature sampling is then employed for calculating statistical moments of the design response. The combination of the above techniques greatly reduces the computational cost in evaluating the statistical moments and enables a semi-analytical approach that evaluates the shape sensitivity of the statistical moments using shape sensitivity at each quadrature node. The applications of our approach to structure and compliant mechanism designs show that the proposed RSTO method can lead to designs with completely different topologies and superior robustness.
Minimal geodesics on groups of volume-preserving maps and generalized solutions of the Euler equations

The three-dimensional motion of an incompressible inviscid fluid is classically described by the Euler equations but can also be seen, following Arnold [1], as a geodesic on a group of volume-preserving maps. Local existence and uniqueness of minimal geodesics have been established by Ebin and Marsden [16]. In the large, for a large class of data, the existence of minimal geodesics may fail, as shown by Shnirelman [26]. For such data, we show that the limits of approximate solutions are solutions of a suitable extension of the Euler equations or, equivalently, are sharp measure-valued solutions to the Euler equations in the sense of DiPerna and Majda [14]. © 1999 John Wiley & Sons, Inc.
Visualisation methods for complex nematic fields

In analysis of numerically simulated or experimentally obtained nematic textures, data visualisation plays an important role in interpretation and comparison of results. We review both commonly used, and more recently developed visual presentation methods that expose different aspects of the textures, from director field patterns and topological content of nematic defects, to deformation modes and simulated optical effects. We outline the theoretical background and potential uses, with examples that highlight the features of each of the described techniques.
Microwave imaging with a time-reversed finite-difference time-domain technique

A novel approach to microwave imaging in three dimensions based on time-reversed finite-difference time-domain method (FDTD-TR) is presented. The proposed computationally efficient technique allows the reconstruction of detailed images of scattering objects. Transmissions as well as reflection imaging modalities in the near-field and far-field were investigated. In this study, we implemented the FDTD-TR algorithm in three dimensions using time-reversed convolutional perfectly matching layers as boundaries to truncate the simulation domain. The method works for dielectric as well as conducting objects. The method’s capabilities in imaging multiple objects and behind-the-wall imaging are also presented.
Extension of Smoothed Particle Hydrodynamics (SPH), Mathematical Background of Vortex Blob Method (VBM) and Moving Particle Semi-Implicit (MPS)

SPH has a reasonable mathematical background. Although VBM and MPS are similar to SPH, their ma-thematical backgrounds seem fragile. VBM has some problems in treating the viscous diffusion of vortices but is known as a practical method for calculating viscous flows. The mathematical background of MPS is also not sufficient. Not with standing, the numerical results seem reasonable in many cases. The problem common in both VBM and MPS is that the space derivatives necessary for calculating viscous diffusion are not estimated reasonably, although the treatment of advection is mathematically correct. This paper discusses a method to estimate the above mentioned problem of how to treat the space derivatives. The numerical results show the comparison among FDM (Finite Difference Method), SPH and MPS in detail. In some cases, there are big differences among them. An extension of SPH is also given.
Duoplasmatron Ion Beam Source for Vacuum Sputtering of Thin Films

A variation of the von Ardenne type of a duoplasmatron ion source is described. Here the arc discharge is maintained between the cathode in the high pressure and the anode in the vacuum chamber, as opposed to the conventional arrangement in which the arc discharge is confined primarily to the high pressure chamber. This modification allows the extraction, through apertures, of a well defined ion beam of current up to 500 mA over an area ∼1 cm2 into a vacuum chamber at a pressure of ∼10−5 Torr. The ion beam is accelerated and made to impinge on a target material for sputtering. Sequential sputtering of different targets inside the vacuum chamber is possible with the help of suitable magnetic fields. The ion beam has been used to sputter conducting, semiconducting, and insulating target materials. Typical rate of deposition of silver films at a distance of 8 cm from the target with a 50 mA, 2 kV ion beam of 8 mm diam is ∼400 A/min. Deposition rates of ∼50 A/min are obtained for SiO2 and TiO films. Vacuum sp.
Photonic nanojet calculations in layered radially inhomogeneous micrometer-sized spherical particles

A photonic nanojet (PNJ) corresponds to the specific highly localized spatial region of electromagnetic near-field distribution in the vicinity of a transparent micrometer-sized particle illuminated by a light wave. Here we consider dielectric spherical composite particles consisting of a core and several concentric shells having different refractive indices. The longitudinal and latitudinal sizes of a PNJ and its peak intensity depending on the optical contrast variation of shells are numerically investigated. We show that by properly changing the refractive indices of neighboring shells, it is possible to manipulate the PNJ shape and, in particular, extend its longitudinal size or increase its peak intensity.