Miracle-dz/UniFAR-FTUs huggingface dataset:
Effective cubic nonlinearity and cnoidal waves in the degenerate parametric frequency conversion

It is shown that under the degenerate conditions (SHG and type-I degenerate parametric generation), the increase in the order of a system of truncated wave equations reduces the initial problem to the solution of two independent nonlinear Schrödinger equations, which allows one to write down the analytic solutions of the corresponding problems by using the standard methods for constructing the searched-for solutions in the form of cnoidal waves. It is established that in realising of cascade processes (quasi-synchronism), one of which is degenerate, this approach based on the introduction of the concept of the effective cascade cubic nonlinearity is not very convenient because the latter in the general case is no longer the Kerr one.
Hamiltonian analysis of fluids in equal-time and light-cone basis

Ideal fluid dynamics is studied as a relativistic field theory with particular importance on its hamiltonian structure. The Schwinger condition, whose integrated version yields the stress tensor conservation, is explicitly verified both in equal-time and light-cone coordinate systems. Finally, a non-relativistic reduction of the system in light-cone coordinates has been carried out. Our dynamical approach reproduces results found earlier by a purely algebraic approach.
Investigation of three-dimensional two-phase flow structure in a bubbly pipe flow

A measurement study was performed to obtain a full-field quantitative description of a three-dimensional, two-phase bubbly flow. Particle image velocimetry (PIV), a whole-field, non-invasive velocity measurement technique, was utilized. PIV is capable of producing an instantaneous velocity map of steady-state and transient flows of a fluid seeded with microscopically small neutral density particles. The objective of this investigation was to study the turbulence structure in a co-current bubbly flow. The obtained information will help to determine parameters needed for two-phase flow modelling. The study investigated the influence of bubbles on the surrounding flow field (bubble/flow interaction). A stereoscopic reconstruction technique was used to obtain three-dimensional velocity vector data from the recorded planar images. Radial distributions of volume-averaged turbulence intensities and Reynolds stresses were calculated. The volume-averaged turbulent kinetic energy within the measurement zone due to a rising bubble is presented.
High responsivity tunable step quantum well infrared photodetector

Abstract : In this thesis, the performance of a step quantum well infrared photodetector (QWIP), which was designed to detect a laser spot at 1.05 m and IR radiation between 9.5 m to 10.5 m, was evaluated. In the far infrared (FIR), the maximum responsivity of the test detector at 10 K was measured at 1.02 A/W with a peak wavelength of 10.3 m under a negative bias of 0.83 V. The D* at background limited infrared performance (BLIP) was measured at 8.0x10(9) cm square root Hz/W with 180 degrees field of view. The BLIP temperature was found to be about 55 K. In addition, the FIR detection wavelength found shift with the amount of bias across the device. The amount of shift observed was 0.21 meV/KVcm-1 which is due to linear Stark effect associated with the step quantum well. The quantum well infrared detectors made of square quantum wells found to have an order of magnitude lower Stark shift originated from second order effects. This suggests that the step well infrared detector can have applications in tunable wavelength infrared detectors.
15O and 13N production by Van de Graaff accelerator (for medical use)

Yields quoted previously (see abstr. A73833 of 1973) have proved to be optimistic and are now expected to be 10-15 mCi of 15O and 5-6 mCi of 13N at the 25-30 mu A capacity of the University of Virginia 5.5 MeV accelerator.
Performance evaluation of hybrid millimeter wave systems under limited information

The increase of electronic devices with wireless connections, end up presenting problems to the current architectures. The current 4G architecture can not handle the demands that arise from the increase of users and it will be necessary to deal with higher traffic and connections with higher transmission rate. Consequently, to meet these requirements, new technologies and techniques are needed for the next generation(5G). Techniques such as the use of millimeter waves, combined with terminals equipped with large antenna arrays or massive number of antennas, although promising and presenting good results, bring with them new problems. Millimeter waves due to the smaller wavelength will allow systems with massive number of antennas. New transmit and receive signal processing (e.g. hybrid beamforming) has been proposed for millimeter wave communications combined with a massive number of antennas. However, transmit beamforming requires the knowledge of channel state information prior to the transmission. Therefore the design of efficient feedback techniques is of paramount importance for pratical systems. This issue is more relevant for massive MIMO based systems than for the conventional MIMO systems. For the first one the channel information to fed back is much higher. In this dissertation a low-overhead feedback channel quantization scheme is proposed. Then, a single-user mmW massive MIMO system is evaluated under the developed quantization strategy. It was considered a transmitter employing a hybrid analog-digital equalizer. The considered techniques quantizes separately some channel parameters, such as complex fading amplitudes, transmit and receive array response. After that, these quantized parameters are fed back to the transmitter and the channel is reconstructed in order to compute the transmit beamformers. The results have shown that a very low number of bits is needed to obtain a performance close to the one obtained with perfect channel information.
Effect of thermal lensing on the mode matching between pump and laser beams in Cr4+:forsterite lasers: a numerical study

The numerical study presented in this paper investigates the role of thermal lensing on the mode matching between the pump beam and the cavity beam in continuous-wave end-pumped Cr4+:forsterite lasers. A suitable mode overlap function was first derived to calculate the degree of overlap between the pump beam and the fundamental mode of the resonator. The effect of thermal lensing on mode matching was then numerically investigated by calculating the changes in the average value of the mode overlap function due to variations in pump power and crystal boundary temperature. Thermal lensing was taken into account by calculating the pump-induced thermal gradients and by approximating the gain medium as a distributed quadratic lens. Finally, the model was used to offer guidelines about how one of the resonator lenses should be readjusted in order to maintain optimum mode matching as the boundary temperature and pump power are varied.
Optical Bistability in Graded Core-Shell Granular Composites

The intrinsic optical bistability (OB) of graded core-shell granular composites is investigated. The coated particles are made of cores with gradient dielectric function ∊c(r) = A(r/a)k and nonlinear shells. In view of the exponential distribution of the core dielectric constant, the potential functions of each region are obtained by solving the Maxwell equations, and the mathematical expressions of electric field in the shells and cores are determined. Numerical study reveals that the optical bistable threshold and the threshold width of the composite medium are dependent on the shell thickness, core dielectric exponent, and power function coefficient. The optical bistable width increases with the decreasing shell thickness and the power exponent and with the increasing power function coefficient.
A Customized and Flexible Ideal Mobile Banking System Using 5G Technology

The word Ideal System refers to a system which is optimal or finest in terms of all its characteristics and any existing system can be improved or converted into the Ideal system by comparing existing system to Ideal system and by doing research and innovation. Mobile banking business will enable banking organizations to expand their markets, improve their services to all corners of the world without any barriers in terms of time, location and place. The rapid increase of mobile phone users is closely followed by security problems. The objective of this paper is to suggest some characteristics that will solve problems like security, bandwidth, network coverage, speed and much more. Fifth Generation (5G) mobile wireless communication technology an advanced modern upcoming technology that has significant change or difference in terms of bandwidth, speed access, and zone issues compare to its predecessors. In this paper, the concept of the Ideal mobile banking system is discussed, based on developing a suitable model with the predicted system and environmental characteristics which is ultimately very much user-friendly, customization and flexible in nature. To realize Ideal system model we have taken up 5G mobile wireless communication technologies and discussed how it will support Ideal mobile banking model by providing characteristics in terms of speed, bandwidth, data transfer rate, signaling efficiency and all advanced services. The paper makes an analysis of new model with its advantages, benefits, constraints, and disadvantages.
Energy-Efficient Multicast Precoding for Massive MIMO Transmission with Statistical CSI

In this paper, we investigate energy-efficient multicast precoding for massive multiple-input multiple-output (MIMO) transmission. In contrast with most previous work, where instantaneous channel state information (CSI) is exploited to facilitate energy-efficient wireless transmission design, we assume that the base station can only exploit statistical CSI of the user terminals for downlink multicast precoding. First, in terms of maximizing the system energy efficiency, the eigenvectors of the optimal energy-efficient multicast transmit covariance matrix are identified in closed form, which indicates that optimal energy-efficient multicast precoding should be performed in the beam domain in massive MIMO. Then, the large-dimensional matrix-valued precoding design is simplified into an energy-efficient power allocation problem in the beam domain with significantly reduced optimization variables. Using Dinkelbach’s transform, we further propose a sequential beam domain power allocation algorithm which is guaranteed to converge to the global optimum. In addition, we use the large-dimensional random matrix theory to derive the deterministic equivalent of the objective to reduce the computational complexity involved in sample averaging. We present numerical results to illustrate the near-optimal performance of our proposed energy-efficient multicast precoding for massive MIMO.
Damping of global Alfven waves in tokamaks due to resonant absorption

The MHD spectrum of circular cross-section tokamak plasmas with small aspect ratio is studied for low mode numbers. Particular attention is given to the continuous part of the ideal MHD spectrum of such plasmas. Poloidal mode coupling in finite aspect ratio tokamaks yields gaps in the Alfven continuum. Global Alfven modes are found with a frequency inside these gaps. By interaction with the continuum branches the global Alfven modes experience damping via phase-mixing. This damping is computed in resistive MHD. It is shown that for asymptotically small resistivity the damping is finite and independent of eta .
Spatial 1/f Spectra in Open Dynamical Systems

A new mechanism for spatial 1/f power spectra is proposed for a type of open dynamical system. This mechanism has two competing ingredients. One tends to preserve the long-range correlations while the other tends to destroy it. A specific model with this mechanism based on a class of extremely simple context-free grammars is analyzed. In this model replication and transposition are repeated applied to a string of discrete elements. Computer experiments show that for a wide range of parameter values, the model yields spatial power spectra of the form 1/fα with α close to 1. The frequency range spanned by the 1/fα form as well as the exponent α depend on the probability with which replication and transposition operations are applied.
Adaptive multi-grid FE simulation on dynamic damage and seismic failure of concrete structures

This paper presents a new adaptive multi-grid method for analyses on damage and failure in concrete column under cyclic loading. Self-adaptation of the method can carry out automatically coupling analysis on the process of evolving damage to structural failure with dynamic grid-change due to damage, without user intervention in the computation. The theory of multi-grid FEM coupled evolving damage is developed on the basis of the improved variational principle to consider damage evolution, in which the elements in each sub-domain with different grid sizes are under the different state of damage. Then the multi-grid FEM method is provided with the theory and a 3D adaptive mesh refinement procedure. As a case study of the method, the process of evolving damage to failure of a concrete column under cyclic loading is simulated by using the developed method, and the simulated results fit well with the experimental data. The results show that, the developed method is reliable in simulation on evolving damage and failure in concrete column under dynamic seismic loading with lower cost and sufficient precision.
Ion beam irradiation of nanostructures: sputtering, dopant incorporation, and dynamic annealing

We presented an approach to obtain sputter yields of ion irradiated nanoparticles using high resolution scanning elec-tron microscopy ( SEM ) [ 1, 2 ] . The approach compared the cross sectional areas of unirradiated ( A O ) and irradiated ( A i ) nanoparticles derived from of the respective SEM images. The sputter yield SY was then calculated from the volume ratio using where ρ at is the atomic density of the target material and f the ion ﬂ uence.Thisformula is correct in ﬁ rst approximation. However, it does not account for the decrease of the projection area ( A 0 ) during irradiation which becomes signi ﬁ cant if the ion ﬂ uence and, with this, the difference between initial cross sectional area and cross sectional area of the irradiated nanoparticle is large. More accurately, the number of ions per differential time has to be calculated. If a time interval d t is assumed, the number of sputtered atoms d N sp is given by where r is the nanoparticle radius. The number of ions is given by where A the cross sectional area of
The enclosure method for inverse obstacle scattering problems with dynamical data over a finite time interval

A simple method for some classes of inverse obstacle scattering problems is introduced. The observation data are given by a wave field measured on a known surface, surrounding unknown obstacles over a finite time interval. The wave is generated by the initial data with compact support outside the surface. The method yields the distance from a given point outside the surface to obstacles and thus more than the convex hull.
An Introduction to the Theory of Numbers

1. Farey Series. The theory of numbers has always occupied a peculiar position among the purely mathematical sciences. It has the reputation of great difficulty and mystery among many who should be competent to judge; I suppose that there is no mathematical theory of which so many wellqualified mathematicians are so much afraid. At the same time it is unique among mathematical theories in its appeal to the uninstructed imagination and in its fascination for the amateur. It would hardly be possible in any other subject to write books like Landau's Vorlesungen or Dickson's History, six great volumes of overwhelming erudition, better than the football reports for light breakfast table reading. The excursions of amateur mathematicians into mathematics do not usually produce interesting results. I wish to draw your attention for a moment to one very singular exception. Mr. John Farey, Sen., who lived in the Napoleonic era, has a notice of twenty lines in the Dictionary of National Biography, where he is described as a geologist. He received as a boy "a good mathematical training". He was at one time agent to the Duke of Bedford, but afterwards came to London, where he acquired an extensive practice as a consulting surveyor, which led him to travel much about the country and "collect minerals and rocks". His principal work was a geological survey of Derbyshire, undertaken for the Board of Agriculture, but he also wrote papers in the Philosophical Magazine, on geology and on many other subjects, such as
Low-Cost Thin and Flexible Screen-Printed Pressure Sensor

Commercial pressure sensors are often fabricated using well-established silicon micromachining technologies. The thickness and stiffness of silicon-based sensors make them in most cases unsuitable for the integration into materials and surfaces. We present a flexible pressure sensor fabricated by printing technology. Therefore, an intrinsically pressure sensitive ink is screen printed on interdigital electrodes on a thin and flexible foil substrate. The sensor shows sufficient sensitivity and is applicable in a wide pressure range from 0 to 2 MPa. The sensor can completely be fabricated using a low-cost screen printing process. It is very thin and flexible, making it possible to be applied on curved surfaces or to be integrated into materials in a minimal invasive way.
Symplectic structure on a moduli space of sheaves on the cubic fourfold

We construct a 10-dimensional symplectic moduli space of torsion sheaves on the cubic 4-fold in the 5-dimensional projective space. It parametrizes the stable rank 2 vector bundles on hyperplane sections of the cubic 4-fold which are obtained by the Serre construction from normal elliptic quintics. The natural projection of this moduli space onto the dual projective 5-space is a Lagrangian fibration. The symplectic structure is closely related (and conjecturally equal) to the quasi-symplectic structure induced by the Yoneda pairing on the moduli space.
Standardized Minimalistic Transfemoral Transcatheter Aortic Valve Replacement (TAVR) Using the SAPIEN 3 Device: Stepwise Description, Feasibility, and Safety from a Large Consecutive Single-Center Single-Operator Cohort

ABSTRACT Background: To describe our updated minimalist approach (MA) for transfemoral transcatheter aortic valve replacement (TF-TAVR) using the SAPIEN 3 device and its evolution, as well as associated safety and efficacy parameters from a large cohort of patients. Methods: A stepwise description of the MA technique for TAVR for 300 consecutive patients was detailed. Safety and efficacy parameters were assessed using the VARC-2 criteria at the in-hospital and 30-days follow-up. Results: A total of 300 consecutive patients (80 ± 7 years; median Logistic EuroSCORE of 11.4% [7.5–17.8]) between January 2014 and May 2016 were evaluated. TF-TAVR was performed under conscious sedation in 247 (82%) patients. Device success was achieved in 286 (95.6%) patients, and intended prosthesis performance in 289 (96.3%) patients. Significant paravalvular leak (PVL) graded more than mild was noted in 7 (2%) patients. No patient had severe PVL. All-cause mortality was noted in one (0.3%) patient in-hospital and in 2 (0.7%) patients at the 30-days follow-up. Major stroke occurred in 4 (1.3%) patients. 9 (3%) patients had major vascular complications at 30-days follow up. MACCE (VARC-2 criteria) were observed in 21 (7%) in-hospital and 25 (8.3%) at 30 days. A new permanent pacemaker implantation was required in 29 (10.7%) patients, and was reduced from 18% to 5.6% (p = 0.001) in a subgroup analysis considering higher implantation position of the valve after the first year of experience. Conclusion: MA of TF-TAVR, when simplified and standardized, is reproducible, safe and efficient, and should be encouraged to be accepted as the standard method of care.
Design methodology of a passive damped modified LCL filter for leakage current reduction in grid-connected transformerless three-phase PV inverters

Although grid-connected transformerless photovoltaic (PV) inverters present higher efficiency and power density compared with inverters with a transformer, the leakage current caused by the inverter common-mode voltage introduces several problems. Among the techniques to reduce the leakage current, the modified LCL (MLCL) filter with passive damping is an effective and simple solution. However, the classical design of the filter damping resistance is not adequate for ensuring both proper leakage current attenuation and control system stability. Therefore, this study proposes a methodology to design the resistance in a low-loss passive damping structure applied to the MLCL filter. In addition to the conventional specifications for LCL-type filters, this study includes the leakage current limit in the design procedure. Simulation and experimental results for a 10 kW PV inverter show the damping resistance impact on the leakage current. The results related to the efficiency and grid inductance variation are also presented. Therefore, it is possible to conclude that the proposed design methodology is very useful for obtaining a damping resistance that ensures control system stability and a leakage current in conformity with PV standards.
The Melvin universe in Born-Infeld theory and other theories of nonlinear electrodynamics

We derive a Melvin universe-type solution describing a magnetic field permeating the whole universe in gravity minimally coupled to any nonlinear electromagnetic theory, including Born-Infeld theory. For a large set of nonlinear electrodynamics theories, our solution is complete and non-singular, as long as the magnetic field is sub-critical. We examine some properties of the solution; in particular, there is a shift of the symmetry axis and a non-standard period along the orbits of the U(1) symmetry to avoid a conical singularity. We show these are consistent with the usual Dirac quantization condition for the magnetic flux. We find exact solutions describing propagation of waves in the `generalized Melvin universe' along the principal null directions of the electromagnetic field, where the Boillat and Einstein lightcone touch. By electric-magnetic duality we show that similar Melvin electric and dyonic universes can be obtained.
The generation of laser shock waves in a water-confinement regime with 50 ns and 150 ns XeCl excimer laser pulses

The generation of shock waves by laser-induced plasma in a water confinement regime has been investigated with 0.308 µm/50 ns and 0.308 µm/150 ns excimer laser pulses. Shock-wave profiles have been characterized by numerical simulations of rear surface velocity measurements behind Al foils with the use of a velocity interferometer system. The results are compared with those obtained with the third harmonic of a Nd:Yag. Above 1-2 GW cm-2, pressure levels saturate at 2-2.5 GPa and the pressure duration is much shortened by laser plasma breakdown which occurs in water. Therefore we suggest that this parasistic plasma generation is favoured by long pulse durations and a laser with short wavelengths.
Electron attachment in water vapour and ammonia

Electron attachment has been studied in water vapour and ammonia over the range E/N=0-91 Td. It has been shown that attachment proceeds via the dissociative attachment process for E/N greater than 40 Td in water vapour and 30 Td in ammonia. With the use of published values of electron drift velocities for these gases the attachment rate coefficient has been calculated. No evidence for any low-energy three-body attachment processes was observed.