Miracle-dz/UniFAR-FTUs huggingface dataset:
Measurement of plasma current dependent changes in impurity transport and comparison with nonlinear gyrokinetic simulationa)

Measured impurity transport coefficients are found to demonstrate a strong dependence on plasma current in the core of Alcator C-Mod. These measurements are compared directly with linear and nonlinear gyrokinetic simulation in an attempt to both qualitatively and quantitatively reproduce the measured impurity transport. Discharges constituting a scan of plasma current from 0.6 to 1.2 MA were performed during the 2010 run campaign. The impurity transport from these discharges was determined using a novel set of spectroscopic diagnostics available on Alcator C-Mod. This diagnostic suite allowed for the effective constraint of impurity transport coefficient profiles inside of r/a = 0.6. A decrease in the measured impurity diffusivity and inward convection is found with increased plasma current. Global, nonlinear gyrokinetic simulations were performed using the GYRO code [J. Candy and R. E. Waltz, J Comput. Phys. 186, 545 (2003)] for all discharges in the experimental scan and are found to reproduce the exper.
A New Fast Iterative Method for Interpolation of Multivariate Scattered Data

Abstract This paper presents Iterative Scalable Smoothing (ISS), a new itera- tive multi-scale method for multivariate interpolation of scattered data. Each iteration step in the process reduces the residues of the current interpolation result by appli- cation of a smoothing operator to a piecewise constant function that interpolates the residues of the current interpolant, and by adding the resulting function to the current approximation, which is initially set to zero. The convergence of the method is proved and conditions for the di®erentiability of the convergence result are given. For a uni- form mesh an e±cient algorithm is constructed, for which the numerical complexity is estimated. Several 2D numerical examples illustrate the theoretical results. By a 3D test with several test-functions and random nodes it is shown that the accuracy of the proposed method is comparable with the quadratic modiffcation of Shepard's method, which is known to be more accurate than triangle-based methods. Then, in 1D tests, by stochastic simulation with random nodes and random functions the ISS method is compared with the Cubic Splines method, Shepard's method and the Kriging method. We also compare the stability of these methods with respect to noisy data. For the special case of regular nodes, properties of the method are verified by comparing its 1D response function with the response function of the cubic spline and the perfect interpolator (the sinc-function). Special attention is paid to the e®ect of the tuning parameter
Oils Derived from GM Crops as Sustainable Solutions to the Supply of Long-Chain Omega-3 for On-Growing Atlantic Bluefin Tuna (Thunnus thynnus L.)

Recently Camelina sativa, has been genetically modified to produce oils rich in omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), EPA (eicosapentaenoic acid) and EPA + DHA (docosahexaenoic acid). The aim of this study was to test the feasibility of using these novel sources of de novo EPA and EPA + DHA as substitutes for marine oil in feeds for juvenile Atlantic Bluefin tuna (ABT). The results showed the oils were practical sources of n-3 LC-PUFA which could potentially replace fish oil (FO) in feeds for ABT juveniles. Fish fed the test diets (ECO, EPA alone and DCO, EPA + DHA) displayed good growth performance, survival and feed utilisation approaching that of ABT fed the reference diet (MGK) containing marine fish oil with the rank order being MGK > DCO > ECO. The test diets showed positive effects, upregulating the expression of genes of major nuclear receptors and those of lipid metabolism including digestion, LC-PUFA synthesis and antioxidant pathways. The results indicated that the DCO feed containing both DHA and EPA performed better than the ECO feed with much lower DHA. However, feeds formulated with both these oils may still require supplementary DHA to satisfy the high requirement of ABT for this essential nutrient.
The Clifford Paterson Lecture, 1993, Accurate measurement in in vivo magnetic Resonance: an engineering problem?

Measurement in in vivo magnetic resonance — both in imaging and spectroscopy — has proved to be a much more intractable problem than extrapolation from conventional high resolution studies might have suggested. Although this paper concentrates mainly on some of the complications of magnetic resonance imaging, the same conceptual difficulties (compounded by much reduced signal levels) affect in vivo spectroscopy. Tissue is an extremely complex system and many of the difficulties studying it arise from the interactions that are unintentionally engendered when it is observed. Patient motion is a potent source of artifact to the technical challenge of making better measurements, and different forms of motion are likely to be the ultimate limitation on the sensitivity and discrimination of the technique as a whole. In this context it is observed that the traditional criterion of performance — system signal-to-noise ratio — should be replaced by a signal-to-artifact estimate, and that this may affect the design and implementation of detector systems to a significant extent.
Asymptotics of Eigenvalues and Unit-Length Eigenvectors of Sample Variance and Correlation Matrices

Multivariate asymptotic (normal) distributions for eigenvalues and unit-length eigenvectors of sample variance and correlation matrices are derived. Beside the general case, when existence of the (finite) fourth-order moments of the population distribution is assumed, formulae for the asymptotic variance matrices in the cases of normal and elliptical populations are also derived. It is assumed throughout that population variance and correlation matrices are nonsingular and without multiple eigenvalues.
Farsi handwritten character recognition with moment invariants

This paper introduces an experimental evaluation of the effectiveness of utilizing various moments as pattern features in recognition of the handwritten Farsi characters. The moments that have been used are Zernike moments, pseudo Zernike moments, and Legendre moments. We have used an unsupervised neural network (ART2) for this application, so that the clusters are formed only based on inherent properties of pattern features. The performance of classification is dependent on the moment order as well as the type of the moment invariant, but the classification error rate was below 10% in all cases. The pseudo Zernike moments of order 5 had the best performance among all the moment invariants. Its error rate and discrimination factor were 3.06% and 96.92% respectively.
Polarization in lamp-post model of black-hole accretion discs

We revisit the lamp-post geometry of the black-hole accretion disc with a primary illuminating source on the rotational axis. The primary X-ray power-law radiation is Compton reflected from the disc towards the observer. The gravitational field of a rotating black hole influences the photon properties on its way from the primary source to the disc and from the primary source and accretion disc to a distant observer. We study the polarization properties of the radiation how they would be observed in this scenario. The degree and the angle of polarization are examined as functions of the black hole spin, observers inclination angle and the position of the primary source.
Salient Features of a Lecture Course on Reliability Theory

The module ‘oReliability Modelling and Analysis’ has been taught by the author at the University of Bradford in the School of Informatics over several years. In this paper, four aspects of the lecture course are described. After reviewing the general course structure, we examine within the field of maintenance modelling the method of marginal cost analysis. The application of this technique is deemed to be novel in the present (teaching) context and it is intended to make a basically mathematical subject amenable also to engineers and economists. Next, we outline the use of the computer algebra package Maxima in teaching ‘reliability’. This is exemplified with a classroom example, an exercise and a coursework assignment. Experience shows that the use of Maxima enriches the teaching of reliability to aspiring practitioners. Finally, some general principles are reviewed which help the learner to keep an eye on the reasonableness of purported results, using properties such as model structure, model symmetry, dimensional correctness, boundary conditions, specialization and generalization.
On Semidefinite Programming Relaxations of Association Schemes with Application to Combinatorial Optimization Problems

We construct convex, semidefinite programming (SDP) relaxations of the convex hull of association schemes with given parameters. As an application, we obtain new and known SDP relaxations of several combinatorial optimizations problems, including the traveling salesman and cycle covering problems (by considering the Lee association scheme) and the maximum p-section problem (by considering the scheme of the complete p-partite graph). Thus, the approach in this paper may be seen as a unified framework to generate SDP relaxations of various combinatorial optimization problems.
The micro-mechanical properties of ion irradiated tungsten

Micro-mechanical testing techniques have proved successful in extracting the properties of bulk materials from small-scale tests. In particular, focussed ion beam (FIB)-machined micro-cantilevers have been shown to produce quantitative, accurate modulus values when used on materials such as pure copper or silicon. In this work, this technique is extended to study the micro-mechanical properties of ion-irradiated, commercially pure tungsten. Ion irradiation has been used to model the cascade damage produced by fusion neutrons in tungsten. Due to the small depth of ion-implanted layers, micro-mechanical tests must be carried out to determine the mechanical properties of the material. These cantilever tests and additional nanoindentation produces data comparable with literature data. An increase in hardness after implantation is measured, while the yield stress of the material remains unchanged. Helium implantation has an effect on the mechanical properties of tungsten. It is hypothesized that this is due to a change in the damage formed under irradiation, from dislocation loops formed in self-ion irradiation to helium-filled vacancies in simultaneous irradiation.
Diffusion Constants near the Critical Point for Time-Dependent Ising Models. I

The diffusion constant of spins in ferromagnets or of molecules in binary mixtures near the critical point is discussed employing a time-dependent Ising model in which spin interactions are replaced by certain temperature-dependent transition probabilities of spin exchange. The spin diffusion constant is calculated with the single approximation of replacing a reduced spin distribution function by its value for local equilibrium with a given inhomogeneous spin density. The behavior of the diffusion constant near the critical point is dominated by a factor ${\ensuremath{\chi}}^{\ensuremath{-}1}$, where $\ensuremath{\chi}$ is the magnetic susceptibility. This problem is also studied with the use of the Bethe lattice. The effects of surrounding spins on the transition probability for spin exchange are found to be essential for obtaining the critical slowing-down near the critical point. In view of this, Koci\ifmmode \acute{n}\else \'{n}\fi{}ski's calculation of the spin diffusion constant is critically discussed.
Consistency of maximum likelihood estimators for the regime-switching GARCH model

The regime-switching GARCH (generalized autoregressive conditionally heteroscedastic) model incorporates the idea of Markov switching into the more restrictive GARCH model, which significantly extends the GARCH model. However, the statistical inference for such an extended model is rather difficult because observations at any time point then depend on the whole regime path and the likelihood becomes intractable quickly as the length of observations increases. In this paper, by transforming it into an infinite order ARCH model, we obtain the possibility of writing a likelihood which can be handled directly and the consistency of the maximum likelihood estimators is proved. Simulation studies to illustrate the consistency and asymptotic normality of the estimators (for both Gaussian and non-Gaussian innovations) and a model specification problem are presented.
VARIANCE COMPONENT ESTIMATION AND PRECISE GPS POSITIONING: CASE STUDY

The underlying motivation of variance component estimation (VCE) is to construct an adequate variance-covariance (VC) matrix for the processing of global positioning system (GPS) code and phase data. Prior to developing a full procedure for VCE in precise GPS positioning, an experimental inventory has been carried out to get acquainted with the key issues in the stochastics of the GPS range observables, and hence with the structure of the eventual VC matrix. The experiences of this inventory are shown in this contribution aspect by aspect, using code and phase data of a geodetic dual frequency receiver pair on a zero baseline at a 1 s sampling interval. The paper treats elevation dependent variances, covariances between channels and between observation types, as well as time correlation. For each aspect easy-to-compute formulas are derived and attention is paid to the redundancy necessary to obtain sensible results. For the receiver at hand, elevation dependence of variance, correlation between observation types, and time correlation are found to be significant.
A study of the coherence parameter of the progressive compressive imager based on radon transform

We have recently introduced a progressive compressing sensing method based on an appropriate sampling scheme of optical Radon projections. By choosing the sampling steps to be of the size of the golden angle new information is optimally acquired with each angular sampling step thus permitting gradual improvement of the reconstructed image. A comparison between the progressive sampling scheme with the conventional one based on uniform sampling is given in terms of their coherence parameter.
Cesiation of W(001): Work function lowering by multiple dipole formation

Rigorous, self-consistent, all-electron, full potential linearized augmented plane wave studies reveal that the lowering of the W(001) work function upon cesiation arises from a complex multiple dipole formation mechanism: Essentially, Cs forms a metallic overlayer with its valence electrons strongly polarized and its 5p semicore shell polarized oppositely.
Convective updraught evaluation in high‐resolution NWP simulations using single‐Doppler radar measurements

This study presents an evaluation of the size and strength of convective updraughts in high‐resolution simulations by the UK Met Office Unified Model (UM). Updraught velocities have been estimated from range–height indicator (RHI) Doppler velocity measurements using the Chilbolton advanced meteorological radar, as part of the Dynamical and Microphysical Evolution of Convective Storms (DYMECS) project. Based on mass continuity and the vertical integration of the observed radial convergence, vertical velocities tend to be underestimated for convective clouds due to the undetected cross‐radial convergence. Velocity fields from the UM at a resolution corresponding to the radar observations are used to scale such estimates to mitigate the inherent biases. The analysis of more than 100 observed and simulated storms indicates that the horizontal scale of updraughts in simulations tend to decrease with grid length; the 200 m grid length agreed most closely with the observations. Typical updraught mass fluxes in the 500 m grid length simulations were up to an order of magnitude greater than observed, and greater still in the 1.5 km grid length simulations. The effect of increasing the mixing length in the sub‐grid turbulence scheme depends on the grid length. For the 1.5 km simulations, updraughts were weakened though their horizontal scale remained largely unchanged. Progressively more so for the sub‐kilometre grid lengths, updraughts were broadened and intensified; horizontal scale was now determined by the mixing length rather than the grid length. In general, simulated updraughts were found to weaken too quickly with height. The findings were supported by the analysis of the widths of reflectivity patterns in both the simulations and observations.
BUNVIS-RG - Exact frame buckling and vibration program, with repetitive geometry and substructuring

BUNVIS-RG is a computationally efficient FORTRAN 77 program which uses an exact stiffness matrix method to find the eigenvalues (i.e., critical load factors, or natural frequencies of vibration) and modes of three-dimensional frames without making the usual approximations of conventional finite element analyses. BUNVIS-RG includes: axially loaded Timoshenko or Bernoulli-Euler beams with distributed mass; taut strings; tapered and other nonuniform members; very efficient computation of modal densities; initial static calculations which include prestress and acceleration; dead and live load in buckling problems; rigid body modes; bandwidth reduction; treatment of stayed columns as substructures; treatment of linearly and rotationally periodic structures by analyzing a single repeating element; and elastic and offset connections between members and nodes. These and other features of BUNVIS-RG are described in this paper, which also gives results to illustrate its scope and efficiency and to establish a formula for predicting solution times.
Lateral displacement of a light beam at a ferrite interface

The lateral Goos–Hanchen1 beam shift of a monochromatic plane wave incident from a denser magneto‐optical surface medium to a rarer magneto‐optical surface medium is theoretically investigated using Maxwell’s theory. We found a large but nondivergent enhancement in the beam displacement as the angle of incidence approaches critical angle.
“…Run, Forrest! Run!…”: A Powerful “Hollywood Physics” Activity

The use of short episodes from current big screen movies to drive home topics in general physics—known as “Hollywood Physics”—has received significant exposure in teaching circles.1,2 This paper details use of a video segment that can be used to actually begin a physics course during the first class meeting in the fall.3
Frequency Domain Design Method of the Aeroengine Fuel Servo Constant Pressure Difference Control System with High Performance

The constant pressure difference regulating mechanism is widely used in aeroengine fuel servo metering systems, and it almost decides the metering precision. However, the design theory and design method of the available constant pressure difference regulating mechanism are unclear, and it is difficult to follow the high stability, high accuracy, and high robustness requirements of the modern aeroengine fuel servo metering system. In this paper, the design theory of the constant pressure difference regulating mechanism is revealed, and it indicates that it consists of two basic control units: a state feedback stabilization controller to ensure the asymptotic stability and disturbance rejection performance; and a servo and feed-forward compensator to ensure the asymptotic tracking ability. In addition, based on the frequency domain analysis method, the decisive influences about the control gains of the two control units on the dynamic performance and stability are analyzed. On this basis, a frequency domain design method of the two core control gains is proposed to complete the design task of the closed-loop system. The simulation results show that, under the adverse conditions of 1 MPa strong step disturbance of the inlet pressure and 50 mm2 strong step disturbance of the variable inlet flow area, the steady-state working range of the controlled pressure difference meets 0.92 ± 0.01 MPa, the steady-state error is not more than 1%, the regulation time is not more than 0.01 s, the dynamic overshoot is not more than 10%, and the designed phase margin is more than 70°.
Influence of the sintering process on critical currents, irreversibility lines and pinning energies in multifilamentary MgB2 wires

We have investigated the electrical transport properties for two MgB2 wires containing four MgB2 filaments in an Fe matrix, made by an ex situ process. The two wires differed in their final treatment. While only the mechanical deformation steps were applied to one of them (wire A), the other (wire B) was annealed in an Ar atmosphere to perform sintering of the powder grains. Critical currents were measured by the transport method, at temperatures ranging from 4.2 K to 30 K, and in magnetic fields up to 8 T. Due to the sintering step, critical currents and pinning energies of the wire B strongly increased with respect to the wire A. The analysis of the R(T) curves and current–voltage characteristics revealed that the irreversibility line was affected by the sintering process. An explanation of the observed behaviours is given in terms of the different activation volumes for pinning energies.
Extended thermodynamics of a two group model of the Boltzmann equation

Abstract A multigroup model for the Boltzmann equation is proposed, which has the same structure of the multigroup equations obtained directly by speed discretization, and at the same time guarantees, at any approximation, exact fulfilment of conservation equations. The P 1 approximation and its relationship to extended thermodynamics are also investigated, and some two-group results regarding heat propagation are presented.
Variable depth thermal lesions in rabbit corneas using a tunable thulium fiber laser

Laser-induced thermal changes in the cornea have been used clinically for refractive surgery. This study describes the creation of variable depth thermal lesions in the cornea using a tunable Thulium fiber laser. Thermal lesions were created in fresh rabbit corneas, ex vivo, at three different wavelengths (1873 nm, 1890 nm, and 1904 nm) (n=6 corneas each). All other laser parameters were kept fixed with power of 5.5 W, 25-ms exposure time, and 650-&mgr;m diameter spot, yielding a single pulse exposure of 138 mJ, and a fluence of 42 J/cm2. Optical coherence tomography (OCT) and histology were used to measure pre- and post-operative corneal thickness and lesion dimensions. OCT measurements of pre and post-operative corneal thickness and lesion depth (in microns) were: (1873 nm: 450±30, 801±95, 655±51), (1890 nm: 460±27, 618±70, 332±56), (1904 nm: 448+20, 550±42, 245+36), respectively. By comparison, histologic measurements were: (1873 nm: 470+25, 828+21, 540±31), (1890 nm: 457±13, 625±17, 350±43), (1904 nm: 465±40, 627±35, 239±23), respectively. OCT lesion depth measured 82%, 54%, and 45% of corneal thickness, compared to histologic analysis of 65%, 56%, and 38%. This is the first preliminary test of a compact and tunable Thulium fiber laser for creating variable depth thermal lesions in the cornea. The Thulium fiber laser may have potential use as a replacement for the Ho:YAG and diode lasers for thermal keratoplasty.