Miracle-dz/UniFAR-FTUs huggingface dataset:
A robust pairwise likelihood method for incomplete longitudinal binary data arising in clusters

Clustered longitudinal data feature cross‐sectional associations within clusters, serial dependence within subjects, and associations between responses at different time points from different subjects within the same cluster. Generalized estimating equations are often used for inference with data of this sort since they do not require full specification of the response model. When data are incomplete, however, they require data to be missing completely at random unless inverse probability weights are introduced based on a model for the missing data process. The authors propose a robust approach for incomplete clustered longitudinal data using composite likelihood. Specifically, pairwise likelihood methods are described for conducting robust estimation with minimal model assumptions made. The authors also show that the resulting estimates remain valid for a wide variety of missing data problems including missing at random mechanisms and so in such cases there is no need to model the missing data process. In addition to describing the asymptotic properties of the resulting estimators, it is shown that the method performs well empirically through simulation studies for complete and incomplete data. Pairwise likelihood estimators are also compared with estimators obtained from inverse probability weighted alternating logistic regression. An application to data from the Waterloo Smoking Prevention Project is provided for illustration. The Canadian Journal of Statistics 39: 34–51; 2011 © 2010 Statistical Society of Canada
Magnetic and Magnetoresistive Properties of Pr<formula formulatype="inline"><tex Notation="TeX">$_{1 - {\rm x}}$</tex> </formula>Ca<formula formulatype="inline"><tex Notation="TeX">$_{\rm x}$</tex> </formula>CoO<formula formulatype="inline"><tex Notation="TeX">$_{3}$</tex> </formula> <formula formul

Polycrystalline perovskite Pr<sub>0.7</sub>Ca<sub>0.3</sub>CoO<sub>3</sub> and Pr<sub>0.5</sub>Ca<sub>0.5</sub>CoO<sub>3</sub> have been investigated by electrical resistivity, magnetization, ac susceptibility, and mu SR measurements. The magnetic measurements data indicate that the samples have, at low temperatures, similar properties to the frustrated magnets. The muSR measurements, suggest the presence of magnetic clusters at low temperatures. The electrical behavior has the main features of conduction in a phase separated system: it shows negative magnetoresistance and it is controlled by grain-boundary effects.
Solving Interval Constraints in Computer-Aided Design

Currently available CAD systems require geometric parameters to have fixed values. Valid range information on parameters cannot be properly represented and embedded in existing CAD data. Specifying fixed parameter values implicitly adds rigid constraints on the geometry, which have the potential to introduce conflicts during later design stages. In this paper, a geometric modeling scheme based on nominal interval representation and analysis is presented to represent design uncertainty and inexactness. Parameters are represented by nominal intervals, which contain the information of nominal values, lower bounds, and upper bounds. Interval constraints represent inexactness at the early design stages, uncertainty in the detailed design, as well as the boundary information for design optimization. To solve under-constrained and over-constrained interval problems, iteration-based equation solving methods are used. A generalized nonlinear constraint solving method based on linear enclosure is developed for fast convergence. Inequalities are transformed into equations and can be solved uniformly. Interval subdivision and constraint re-specification methods are developed for design refinement. Active and inactive constraints are differentiated in sensitivity analysis.
Concentric cylindrical metamaterials for subwavelength dark hollow light cones

We report a concentric cylindrical metamaterial (CCM) which can be used for acquiring a dark hollow light cone (DHLC). The proposed structure is composed of a concentric cylindrical silver–dielectric multilayer composite, which is covered by a thin layer of chromium (Cr) containing an annulus or a hole opening for incidence. The simulation results show that nanometer-level dark hollow light cones with good quality can be formed in the output for circularly polarized incidence and its position can be monitored by choosing different dielectric materials and dimensions of annular apertures. Such a dark hollow light cone is believed to have potential applications in manipulating atoms and molecules.
An X-ray temperature map of Abell 754: A major merger

We present the first two-dimensional X-ray temperature map of the rich cluster of galaxies Abell 754. We also present an X-ray surface brightness map with improved spatial resolution and sensitivity compared with previous maps. Both the temperature map and the surface brightness map show that A754 is in the throes of a violent merger; it is probably far from hydrostatic equilibrium.
Downwind Gauß‐Seidel‐Smoothing for Convection‐Dominated Problems

Due to the vanishing ellipticity, multigrid methods for convection‐dominated problems tend to loose their good convergence properties. With a suited discretisation, an appropriate ordering of the unknowns and, if necessary, a special block partitioning, the smoothing property of the Gauß‐Seidel iteration and therefore good convergence can be regained. This paper deals with such an ordering strategy and block partitionings.
Semiclassical Analysis for the Ground State Energy of a Schrödinger Operator with Magnetic Wells

Abstract Motivated by a recent paper by Montgomery [Mon], we give the asymptotic behavior, in the semi-classical sense, of the ground state energy for the Schrodinger operator with a magnetic field. We consider the case when the locus of the minima of the intensity of the magnetic field is compact and our study is sharper when this locus is an hypersurface or a finite union of points
Numerical analysis of the Raman spectrum evolution and soliton pulse generation in single-mode fibers

Numerical simulation is used to investigate the evolution of Raman spectra in the negative group-velocity dispersion regime of fibers for continuous-wave pump radiation. It is shown that the ratio of the pump power to the power of the fundamental soliton with a duration of approximately the inverse of the Raman gain linewidth is of great importance. Depending on its value, either cascade Raman scattering (with successive generation of the discrete Stokes components at relative frequency shifts of ~440 cm−1) or the generation of a Raman continuum is observed. In the time domain such a Raman continuum represents a random sequence of soliton-like pulses. The possibilities of the generation of a single solitonlike pulse from the Raman continuum are analyzed.
A Review of the Optimisation of Photopolymer Materials for Holographic Data Storage

Photopolymers are very interesting as optically sensitive recording media due to the fact that they are inexpensive, self-processing materials with the ability to capture low-loss, high-fidelity volume recordings of 3D illuminating patterns. We have prepared this paper in part in order to enable the recognition of outstanding issues, which limit in particular the data storage capacity in holographic data storage media. In an attempt to further develop the data storage capacity and quality of the information stored, that is, the material sensitivity and resolution, a deeper understanding of such materials in order to improve them has become ever more crucial. In this paper a brief review of the optimisation of photopolymer materials for holographic data storage (HDS) applications is described. The key contributions of each work examined and many of the suggestions made for the improvement of the different photopolymer material discussed are presented.
ARMA model order determination and MDL: a new perspective

Much research has focused on the problem of estimating the model order of autoregressive moving average (ARMA) processes. The most well-known of the proposed solutions for this problem include the final prediction error (FPE), Akaike information criterion (AIC), and minimum description length (MDL). A new approach for model order determination based on the MDL criterion is proposed and shown to depend on the minimum eigenvalue of a covariance matrix derived from the observed data. As a result, a new selection procedure for estimating the model order via MDL is proposed. Examples that illustrate the significantly improved accuracy of the proposed technique are given. <<ETX>>
Spurious regression and econometric trends

This paper analyses the asymptotic and finite sample implications of different types of nonstationary behavior among the dependent and explanatory variables in a linear spurious regression model. We study cases when the nonstationarity in the dependent and explanatory variables is deterministic as well as stochastic. In particular, we derive the order in probability of the t-statistic in a spurious regression equation under a variety of empirically relevant data generation processes, and show that the spurious regression phenomenon is present in all cases when at least one of the variables behaves in a nonstationary way. Simulation experiments confirm our asymptotic results
Small Sample Correction for the Variance of GEE Estimators

When clustered multinomial responses are fit using the generalized logistic link, Morel (1989) introduced a small sample correction in the Taylor series based estimator of the covariance matrix of the parameter estimates. The correction reduces the bias of the Type I error rates in small samples and guarantees positive definiteness of the estimated variance‐covariance matrix. It is well known that small sample bias in the use of the Delta method persists in any application of the Generalized Estimating Equations (GEE) methodology. In this article, we extend the correction originally suggested for the generalized logistic link, to other link functions and distributions, when parameters are estimated by GEE. In a Monte Carlo study with correlated data generated under different sampling schemes, the small sample correction has been shown to be effective in reducing the Type I error rates when the number of clusters is relatively small.
Fabrication and Mechanical Characterization of Micro Electro Mechanical System Based Vertical Probe Tips for Micro Pad Measurements

As a result of new developments in semiconductor technology, the number of pads per unit area is increasing and pad arrays are becoming irregular. Therefore, there is an increased need for a versatile probe card to address these issues. We developed a vertical micro electro mechanical system (MEMS) probe tip that is usable in a small pad (approximately 100 µm) and a two-dimensional pad array. The main process used to produce the tip was wafer bonding, silicon etching by deep reactive ion etcher (RIE) and electro-plating. The material of the electro-plated probe tip was an Ni–Co alloy. To optimize the design of the vertical probe tip, we designed various models and measured them in a micro compression and tensile tester. The structural analyses of the probe tip were accomplished using finite element method (FEM) and compared with actual measurement values. In this study, we demonstrated the potential of the vertical probe tip applied to a small area with the over drive (O.D.) of 10–40 µm and the contact force of 1–8gf.
Further Study of an Optimum Non-linear Control System†

ABSTRACT This paper is the second of two in which the system studied has a plant which consists of two integrators with a saturable control input, and the performance criterion which is to be minimized is integral-error-squared. In the first paper the known optimum controller was shown to satisfy Pontryagin's maximum principle. In the present paper further verification of the optimum system is obtained by showing that the best performance function satisfies Bellman's partial differential equation. It is found that Bellman's equation is even satisfied for points on the switching curve, Results are also given for other performance criteria.
Transition to shear banding in pipe and Couette flow of wormlike micellar solutions

We used both conventional rheometry and nuclear magnetic resonance (NMR) velocimetry to study shear banding in a solution of 200 mM cetylpyridinium chloride and 120 mM sodium salicylate in 0.5 M sodium chloride. The solution behaved as a Maxwell fluid up to frequencies of 10 Hz. Theoretical predictions of critical strain rate and shear stress were in good agreement with measurements obtained using controlled strain rate rheometry. Using NMR velocimetry, we observed convincing evidence of shear banding in capillary flow with a band of very high, approximately constant, shear rate next to the wall that grew in thickness with increasing apparent shear rate. We believe that the shear rate in this band (∼600 s−1) marks the beginning of the hypothesized high shear rate limb of the flow curve. We also observed shear banding in both the cylindrical Couette and cone-and-plate geometries. Shear banding started at shear rates that were approximately the same as the critical shear rate measured with the mechanical rh.
Fluid Dynamics of Pitching and Plunging Flat Plate at Intermediate Reynolds Numbers

A combined numerical and experimental study of two- and three-dimensional pitching and plunging flat plates at Reynolds numbers of O(104) is presented. The focus of this paper is the interplay between the geometry, kinematics, Reynolds numbers, and three-dimensional effects with the resulting aerodynamic forces and flow structures. A shallow-stall and a deep-stall motion with higher maximum effective angles of attacks are considered. Under both kinematic motions, massive leading-edge separation is observed at the sharp leading edge of the flat plate. This geometric effect is seen to dominate over other viscosity effects, and the Reynolds number dependence is limited. Compared with the blunter SD7003 airfoil, where the flow is mostly attached for the shallow-stall motion at Re=6×104, the sharper leading edge of the flat plate leads to earlier and stronger leading-edge vortex formation and greater lift and drag. Finally, the presence of a tip vortex significantly reduces lift generation during the downstrok.
An n Job, One Machine Sequencing Algorithm for Minimizing the Number of Late Jobs

An algorithm, computationally feasible for large problems, has been formulated for sequencing n jobs through a single facility to minimize the number of late jobs. This algorithm is then extended to solve the problem in which each job is associated with a continuous, monotone non-decreasing deferral cost function. The object is to produce a schedule where the maximum deferral cost incurred is minimal.
Vortex shedding and shear-layer instability of wing at low-Reynolds numbers

Flow patterns and characteristics of vortex shedding and shear-layer instability of a NACA 0012 cantilever wing are experimentally studied. Smoke-wire and surface oil-flow techniques are employed to visualize the flow patterns and evolution of vortex shedding. Hot-wire anemometers are used to characterize the frequency domain of the unsteady flow structures. Several characteristic flow modes are classified in the domain of chord Reynolds number and root angle of attack. Effects of the juncture and wing tip are discussed. Vortex shedding can be classified into four characteristic modes. Vortex shedding at low and high angles of attack are found to have different dominant mechanisms. Effects of the juncture and wing tip on the vortex shedding are discussed. Shear-layer instabilities are found to be closely related to the behaviors of the vortex shedding. Behaviors of the shear-layer instabilities can be traced back to the characteristics of the boundary layer on the suction surface of the airfoil.
Shock-Tube Experiments and Kinetic Modeling of Toluene Ignition

Recent ignition delay time studies of toluene ignition (using shock tubes and rapid-compression machines) have not achieved a strong consensus at intermediate temperatures (900-1200 K) and high pressures (near 50 atm). However, the development and refinement of reaction mechanisms for toluene at engine-relevant conditions demand an accurate knowledge of these ignition delay times. To help resolve this issue, we have measured ignition delay times for toluene/air mixtures (φ = 1.0) at high pressures (near 50 atm) over the temperature range of 966 to 1211 K using pressure and emission measurements behind reflected shock waves. The new ignition delay times were found to be in good agreement with the previous study of Davidson et al. [Davidson, D. F. , Gauthier, B. M. , and Hanson, R. K. , "Shock Tube Ignition Measurements of Iso-Octane/Air and Toluene/Air at High Pressures," Proceedings of the Combustion Institute, Vol. 301, 2005, pp. 1175-1182. ]. Although the preignition pressure-time histories varied with the shock-tube loading protocol (e.g., cleaning and passivating), the ignition delay times were not significantly affected. Ignition delay time measurements were also compared with the predictions of several current toluene reaction mechanisms, and updated reaction rate values were suggested to improve modeling performance.
Effect of the electron energy distribution on total energy loss with argon in inductively coupled plasmas

The total energy lost per electron-ion pair lost eT is investigated with the electron energy distribution function (EEDF). The EEDFs are measured at various argon powers in RF inductively coupled plasma, and the EEDFs show a depleted distribution (a discontinuity occurring at the minimum argon excitation threshold energy level) with the bulk temperature and the tail temperature. The total energy loss per electron-ion pair lost eT is calculated from a power balance model with the Maxwellian EEDFs and the depleted EEDFs and then compared with the measured eT from the floating probe. It is concluded that the small population of the depleted high energy electrons dramatically increases the collisional energy loss, and the calculated eT from the depleted EEDFs has a value that is similar to the measured eT.
Self-Sensing Active Magnetic Dampers for Vibration Control

The aim of this paper is to investigate the potential of a self-sensing strategy in the case of an electromagnetic damper for the vibration control of flexible structures and rotors. The study has been performed in the case of a single degree of freedom mechanical oscillator actuated by a couple of electromagnets. The self-sensing system is based on a Luenberger observer. Two sets of parameters have been used: nominal ones (based on simplifications on the actuator model) and identified ones. In the latter case, the parameters of the electromechanical model used in the observer are identified starting from the open-loop system response. The observed states are used to close a state-feedback loop with the objective of increasing the damping of the system. The results show that the damping performance are good in both cases, although much better in the second one. Furthermore, the good correlation between the closed-loop model response and the experimental results validates the modeling, the identification procedure, the control design, and its implementation. The paper concludes on a sensitivity analysis, in which the influence of the model parameters on the closed-loop response is shown.
Collective magnetic properties of cobalt nanocrystals self-assembled in a hexagonal network: Theoretical model supported by experiments

Numerical calculations of magnetization curves versus applied field based on a simple model taking into account dipolar interactions were performed for cobalt nanocrystals deposited on a substrate and organized in a hexagonal network. A random distribution of the easy axes orientations of the nanocrystals is considered. The study is focused on the effect of the applied field orientation relative to the substrate surface. Two orientations were chosen: parallel and perpendicular to the surface. The corresponding hysteresis loops are compared to that of a volumic random distribution of nanocrystals at vanishing concentration. The calculation results are compared to experimental data for spherical cobalt nanocrystals coated by lauric acid $({\mathrm{C}}_{12}{\mathrm{H}}_{25}{\mathrm{COO}}^{\mathrm{\ensuremath{-}}}). $ The particles are either dispersed in hexane (considered as randomly distributed) or deposited in a hexagonal network on a highly oriented pyrolithic graphite substrate. The changes in the magnetization curves with the applied field orientation on the one hand and when going from dispersed to deposited particles on the other hand were calculated and measured. Qualitative agreement is obtained.
Dust formation of Be stars with large infrared excess

Abstract Classical Be stars, in addition to their emission-line spectra, are associated with infrared excess which is attributable to free-free emission from ionized gas. However, a few with exceptionally large near-infrared excess, namely with J–H, and H–Ks both greater than 0.6 mag—and excess emission extending to mid- and far-infrared wavelengths—must be accounted for by thermal emission from circumstellar dust. Evolved Be stars on the verge of turning off the main sequence may condense dust in their expanding cooling envelopes. The dust particles should be very small in size, hence reprocess starlight efficiently. This is in contrast to Herbig Ae/Be stars for which the copious infrared excess arises from relatively large grains as part of the surplus star-forming materials.
Row Ordering for a Sparse QR Decomposition

A new row ordering strategy based on pairing rows to minimize local fill-in is presented. The row ordering can be combined with most column ordering strategies to reduce computation, maintain sparsity, and solve rank deficient problems. Comparison of the new row pairing algorithm with Duff's fixed pivot row ordering on a collection of sparse matrix test problems shows a median 47-71\% reduction, depending on the column ordering, in floating point operations (flops) required for the QR decomposition. On a finite element application using nested domain decomposition for the column ordering, the new row ordering is competitive with the row ordering from nested domain decomposition.
Mapping nonlinear integro-differential equations to a generalized describing function form

An algebraic relationship is derived which enables the generalized amplitude dependent describing function to be expressed in terms of the parameters of a general nonlinear integro-differential equation. The algorithm is not restricted to a specific input, but treats the whole class of harmonically related, phase independent, sinusoidal inputs, and is illustrated by a number of examples.