Miracle-dz/UniFAR-FTUs huggingface dataset:
Delaunay Triangular Meshes in Convex Polygons

An algorithm for producing a triangular mesh in a convex polygon is presented. It is used in a method for the finite element triangulation of a complex polygonal region of the plane in which the region is decomposed into convex polygons. The interior vertices of the mesh are chosen to be on a quasi-uniform grid, different mesh spacings are specified for the edges of the polygon, and the mesh is a Delaunay triangulation. The correctness of the algorithm is proved and the expected time complexity is shown to be linear in the number of triangles in the mesh.
Reordering of Hybrid Unstructured Grids for Lower-Upper Symmetric Gauss-Seidel Computations

This note is devoted to the three-dimensional hybrid grid implementation of the LU-SGS method. The original method was based on sweeps through grid node numbers and was applied to two-dimensional Euler computations. Unfortunately, in its original formulation, the method cannot be vectorized; in addition the method is not compatible with commonly used edge-based data structure. To fit the method to the three-dimensional computations on a vector supercomputer, grid reordering is necessary. It was applied to the cell-centered finite volume method
Whispering gallery modes microcavities with J-aggregates and plasmonic hot spots

We have studied the optical properties of a hybrid system consisting of cyanine dye J-aggregates (both PIC and TDBC) attached to a spherical microcavity. Instead of the commonly accepted chemical bonding of dye molecules to the surface of microspheres or deposition of dye-doped sol-gel film, in our experiments microspheres were coated with J-aggregate shell utilizing the layer-by-layer assembly of the ultrathin films. In this approach we aimed to take advantage of light confinement in the Whispering Gallery Modes (WGMs) microcavity by placing the emitter (shell of J-aggregates) just at the rim of the microsphere, where the resonant electromagnetic field reaches its maximum. A periodic structure of narrow peaks was observed in the photoluminescence spectrum of the J-aggregates, arising from the coupling between the emission of J-aggregates and the WGMs of the microcavity. The most striking result of our study is the observation of polarization sensitive mode damping caused by re-absorption of J-aggregate emission. This effect manifests itself in dominating emission from the transverse magnetic modes in the spectral region of J-aggregates absorption band where the transverse electric (TE) modes are strongly suppressed. Strong suppression of TE modes reflects preferential tangential orientation of transition dipole moment of J-aggregates in deposited microcavity shell. Observed polarization sensitive mode damping observed in the spectral region of high J-aggregate absorption can be used for suppression of unwanted modes in high Q optical resonators. We also demonstrate that the emission intensity can be further enhanced by depositing a hybrid layer of J-aggregates and Ag nanoparticles onto the spherical microcavity. Owing to the concerted action of WGMs and plasmonic hot spots in the Ag aggregates, we observe strongly enhanced Raman signal from the Jaggregates. Microcavities covered by J-aggregates and plasmonic nanoparticles could be thus useful for a variety of photonic applications in basic science and technology.
Nonlinear identification using inverse-repeatm sequences

A Complete formal solution of the Wiener approximation problem in the absence of noise is given for the case when the input is a ternary or an inverse-repeat binary m sequence. The full set of correlation equations are shown to depend on N/2 1st-order and N/2 2nd-order equations, where N is the sequence period; for the ternary sequence, the proof makes use of a new identity in the elements 0, 1, −1. It is concluded that these sequences do not effectively identify kernels of order greater than 2.
Hodographs of Slowly Rotating Winds in Midlatitudes

AbstractTrend analysis of hourly wind direction angle recorded at nine meteorological stations across southern Canada (in the 43°–53°N belt) identified wind direction rotation periods in the range of 7–9 days. Rotation persists during the “summertime” season from May to mid-October during 1953–2001. Rotation with a 7.5-day period was also established in the 850-hPa geostrophic summertime wind over the Canadian province of Saskatchewan in 2000. Hodographs built from wind vectors corresponding to consecutive days of the 7.5-day period (summertime average vectors of winds binned into separate days of the period) formed nearly elliptical loops centered around the end point of the net westerly transport vector that ranged from 0.5 to 1.3 m s−1 and was either smaller than or of comparable magnitude to the zonal and meridional oscillations of wind. The observed rotations appear quasi periodic rather than purely periodic, because nearly elliptical loops of relatively large amplitude were present at different hodo.
Mean square error of regression‐based constituent transport estimates

Estimates of long-term transport of constituents commonly are obtained by summing retransformed estimates from regressions of logarithmically transformed response variables. Typical explanatory variables for these regressions include functions of flow, change in flow, time, and time of year. The mean and mean square error of four estimators of long-term transport at periodically measured stations are presented as a function of the observed values of the explanatory variables from the long-term record and summary statistics of the regression data. Estimates of the mean square errors can be used in designing sampling strategies to attempt to minimize the uncertainty in the estimation of long-term transport subject to a constraint on the number of samples to be taken. This uncertainty is expressed in terms of the explanatory variables in the long-term record, the regression coefficients and standard error of the regression and the mean and covariance structure of the explanatory variables used in the regression.
The collapse of the cores of slowly rotating isothermal clouds

Rotation plays an important role in the formation of stars and planetary systems, but detailed calculations of its effects have been limited by the difficulty of following the collapse from interstellar dimensions to those characteristic of the solar system or binary stars. We present here a semianalytic perturbational solution for the collapse of a slowly rotating cloud core. The initial equilibrium state is exact and corresponds to the uniformly rotating analogue of the singular isothermal sphere. This equilibrium state has a density profile which is proportional to 1/r/sup 2/ in its inner regions and attaches smoothly to a uniform background, a plausible approximation for the core of a molecular cloud plus its envelope. We note that for reasonable values of interstellar parameters, the inner solar mass of the cloud has a total angular momentum on the order of that possessed by the augmented solar system, where the planetary masses are scaled to reflect solar abundances (Hoyle 1960; Safranov 1969). Star (and disk) formation proceeds because the equilibrium is unstable to core collapse. The evolution in time can be followed by performing a perturbational analysis on the known similarity solution for the nonrotating case. The hydrodynamic equations, including self-gravity, can bemore » reduced to a set of linear ordinary differential equations, which is solved by the method of matched asymptotic expansions. The solutions have inner limiting forms that attach smoothly to existing solutions for the buildup of protostars (Stahler, Shu, and Taam 1980a, b; Mercer-Smith, Cameron, and Epstein 1983) and protostellar disks (Cassen and Moosman 1981). Taken together, these calculations provide a self-consistent description of the dynamical collapse of rotating molecular cloud cores and a framework for the study of the formation of stars and nebular disks. « less
Impact of Weather Analysis on Agricultural Production and Planning Decisions for the Semiarid Areas of Kenya

Abstract Kenya's current 4% rate of population growth requires cultivation of food crops by smallholder farmers in ever drier zones of semiarid lands. Rainfall is limited, variable and unpredictable, but maize, widely known for susceptibility to drought, remains the staple and favorite food crop. A case study is presented in which “effective rainfall” for Katumani Composite B-type maize, grown at Katumani, Machakos District, is evaluated for each of the 48 wet seasons in the 24-year record. The newly developed analysis takes into account rainfall, evaporation, soil depth and water holding capacity, and growth characteristics of the crop influencing water uptake and yield. Conclusions are: 1) The analysis evaluates suitability of a given crop for production in any location where rainfall and evaporation records are available. 2) Dates of onset of the rains at Katumani are sortable into periods termed “early” (implies expectation of high to medium water adequacy for maize production), “late” (medium to low .
Numerical investigation of the stress field of particulate reinforced polymeric composites subjected to tension

The aim of the present study is the detailed numerical investigation of the stress/strain distribution in polymeric matrix composites reinforced with spherical inclusions, using the finite element method (FEM). Perfect adhesion between the matrix and the inclusions was assumed and from the computed stress/strain profiles of the system, debonding initiation and propagation can easily be predicted. Analytical models available in the literature may predict the stress/strain distribution within the inclusion and along the matrix/inclusion interface, while the FEM may yield results for the whole composite, including within the inclusions. Three typical volume fractions of the composite were examined and the results were justified by the analytical predictions of other researchers. The numerical results show that the matrix starts to debond from the inclusions at angular distance forty‐five degrees and as the applied load increases the debonding zone gradually extends. Copyright © 2005 John Wiley & Sons, Ltd.
Silicon-based anti-reflective spin-on hardmask materials with improved storage stability for 193-nm lithography

As the feature sizes of integrated circuits shrink, thinner photoresist coating should be used in order to avoid high aspect ratio which can cause pattern collapse. Especially for 193 nm lithography, photoresist coating is too thin to subsequent etching step. One of the solutions to this problem is using hardmasks which have good etch selectivity to adjacent layers. In this paper, silicon-based anti-reflective spin-on hardmasks (Si-SOH) are described. One of the major problems of silicon based polymers in the hardmask compositions is poor storage stability because silanol group is reactive enough to condense each other, which can instigate molecular weight increase to yield gel-type particles. The storage stability of our hardmask materials have been improved by thermodynamically controlled synthesis and reactive mask strategy. Especially the reactive masked silanol groups can take part in crosslinking reaction under the process conditions without additional deprotection step. Although this strategy could encounter intermixing problems with other layers, we can produce silicon-based hardmasks without any deleterious effects. These hardmasks show antireflective properties and great etch selectivity to both photoresists and organic hardmasks (C-SOH).
On the Migratory Behavior of Planetary Systems

For centuries, an orderly view of planetary system architectures dominated the discourse on planetary systems. However, there is growing evidence that many planetary systems underwent a period of upheaval, during which giant planets “migrated” from where they formed. This thesis addresses a question key to understanding how planetary systems evolve: is planetary migration typically a smooth, disk-driven process or a violent process involving strong multi-body gravitational interactions? First, we analyze evidence from the dynamical structure of debris disks dynamically sculpted during planets’ migration. Based on the orbital properties our own solar systems Kuiper belt, we deduce that Neptune likely underwent both planet-planet scattering and smooth migration caused by interactions with leftover planetesimals. In another planetary system, Pictoris, we find that the giant planet discovered there must be responsible for the observed warp of the systems debris belt, reconciling observations that suggested otherwise. Second, we develop two new approaches for characterizing planetary orbits: one for distinguishing the signal of a planets orbit from aliases, spurious signals caused by gaps in the time sampling of the data, and another to measure the eccentricity of a planet’s orbit from transit photometry, ”the photoeccentric e↵ect. ” We use the photoeccentric e↵ect to determine whether any of the giant planets discovered by the Kepler Mission are currently undergoing planetary migration on highly elliptical orbits. We find a lack of such “super-eccentric” Jupiters, allowing us to place an upper limit on the fraction of hot Jupiters created by the stellar binary Kozai mechanism. Finally, iii we find new correlations between the orbital properties of planets and the metallicity of their host stars. Planets orbiting metal-rich stars show signatures of strong planet-planet gravitational interactions, while those orbiting metal-poor stars do not. Taken together, the results of thesis suggest that suggest that both disk migration and planet-planet interactions likely play a role in setting the architectures of planetary systems.
Bayesian Optimization with a Neural Network Meta-learned on Synthetic Data Only

Bayesian Optimization (BO) is an effective approach to optimize black-box functions, relying on a probabilistic surrogate to model the response surface. In this work, we propose to use a Prior-data Fitted Network (PFN) as a cheap and flexible surrogate. PFNs are neural networks that approximate the Posterior Predictive Distribution (PPD) in a single forward-pass. Most importantly, they can approximate the PPD for any prior distribution that we can sample from efficiently. Additionally, we show what is required for PFNs to be used in a standard BO setting with common acquisition functions. We evaluated the performance of a PFN surrogate for Hyperparameter optimization (HPO), a major application of BO. While the method can still fail for some search spaces, we fare comparable or better than the state-of-the-art on the HPO-B and PD1 benchmark.
An H‐matrix Type Preconditioner For Frictional Contact Problems

The bilateral or unilateral contact problem with Coulomb friction between two elastic bodies is considered [1]. An algorithm is introduced to solve the resulting finite element system by a non‐overlapping domain decomposition method [2, 3]. The global problem is transformed to a independant local problems posed in each bodie and a problem posed on the contact surface (the interface problem). The solution is obtained by using a successive approximation method, in each step of this algorithm we solve two intermediate problems the first with prescribed tangential pressure and the second with prescribed normal pressure [8]. Our preconditioner construction is based on the application of the H‐matrix technique [6, 7] together with the representation of the H1/2 seminorm by a sum of partial seminorms [4]. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wave scattering from random sets of closely spaced objects through linear embedding via Green's operators

In this paper we present the application of linear embedding via Green's operators (LEGO) to the solution of the electromagnetic scattering from clusters of arbitrary (both conducting and penetrable) bodies randomly placed in a homogeneous background medium. In the LEGO method the objects are enclosed within simple-shaped bricks described in turn via scattering operators of equivalent surface current densities. Such operators have to be computed only once for a given frequency, and hence they can be re-used to perform the study of many distributions comprising the same objects located in different positions. The surface integral equations of LEGO are solved via the Moments Method combined with Adaptive Cross Approximation (to save memory) and Arnoldi basis functions (to compress the system). By means of purposefully selected numerical experiments we discuss the time requirements with respect to the geometry of a given distribution. Besides, we derive an approximate relationship between the (near-field) accuracy of the computed solution and the number of Arnoldi basis functions used to obtain it. This result endows LEGO with a handy practical criterion for both estimating the error and keeping it in check.
Robust sharp features infer from point clouds

A novel sharp features extraction method is proposed in this paper. First, we calculate the displacement between the point and its local weighted average position and we label the point with salient this value as the candidate sharp feature points and we estimate the normal direction of those candidate sharp feature points by means of local PCA methods. Then we refine the normal estimated by inferring the orientation of the points near the candidate sharp feature region and bilateral filtering in the normal field of point clouds. At last we project the displacement between point and its local weighted average position along the direction of normal . We use value of this projection as the criteria of whether a point can be labeled as sharp feature. The extracted discrete sharp feature points are represented in the form of piecewised B-Spline lines. Experiment on both real scanner point clouds and synthesized point clouds show that our method of sharp features extraction are simple to be implemented and efficient for both space and time overhead as well as it robust to the noise ,outlier and un even sample witch are inherent in the point clouds.
Application of the Finite Piece Method to Simulate Viscoelastic Fluid Flows in L-Shaped Channel

The finite piece method is established to solve the flows of K-BKZ fluid in L-shaped channel. Numerical results are given to compare to the three-dimensional simulation using the finite element method (FEM). It is found that the results are highly consistent as a whole. The error of flow distribution is smaller than 2% at the outlet. There is a minor discrepancy of the pressure in the convergence region of channel but they are restricted to a small region. The present approach demonstrates its superiority over the conventional FEM for analyzing slit flow.
THE EFFECTS OF GRAIN SIZE AND GRAIN GROWTH ON THE CHEMICAL EVOLUTION OF COLD DENSE CLOUDS

We investigate the formation of molecules during the chemical evolution of a cold dense interstellar cloud using a gas–grain numerical code in order to study the effects of grain-size distribution and grain growth on molecular abundances. Three initial size distributions have been used, based on earlier models. To incorporate different granular sizes, we divided the distribution of sizes utilized into five logarithmically equally spaced ranges, integrated over each range to find its total granular number density, and assigned that number density to an average size in that range. We utilized rate coefficients for surface reactions, accretion, and desorption as functions of grain size. We then followed the chemical evolution of the surface populations of the five average-sized grains along with the gas-phase chemistry. We find that the total effective granular surface area of a distribution is an important parameter in the determination of surface abundances, with and without grain growth. The effect on gas-phase abundances can also be sizable. Grain growth with time increases the rate of depletion of molecules, such as CO, produced in the gas phase. Use of a size distribution for grains in gas–grain models does not improve the agreement of calculated and observed abundances, in the gas or on grains, as compared with models containing “classical” grains of a fixed radius of 0.1 μm. This result helps to verify the quality of the classical grain approximation for cold cloud models. Further, it provides an important basis for future gas–grain models.
Large-scale Langmuir circulation and double-diffusive convection: evolution equations and flow transitions

Two-dimensional Langmuir circulation in a layer of stably stratified water and the mathematically analogous problem of double-diffusive convection are studied with mixed boundary conditions. When the Biot numbers that occur in the mechanical boundary conditions are small and the destabilizing factors are large enough, the system will be unstable to perturbations of large horizontal length. The instability may be either direct or oscillatory depending on the control parameters. Evolution equations are derived here to account for both cases and for the transition between them. These evolution equations are not limited to small disturbances of the nonconvective basic velocity and temperature fields, provided the spatial variations in the horizontal remain small. The direct bifurcation may be supercritical or subcritical, while in the case of oscillatory motions, stable finite-amplitude travelling waves emerge. At the transition, travelling waves, standing waves, and modulated travelling waves all are stable in sub-regimes.
Research on Skin Friction Drag Reduction by Vibrant Wall

To reduce aerodynamic drag, reduction of skin friction is required. Vibrant flexible wall has been proposed to reduce skin friction drag for a long time. However, there are many problems for the flexible wall to get practical durability, easy maintenance and reasonable cost. On the other hand, vibrant solid wall, which is much adequate for a car body, has been rarely proposed. In this research, mechanism of drag reduction by a vibrating solid wall is considered from the velocity distribution near the wall surface. Reduction of skin friction drag on a vibrant wall is mainly caused by decrease of Reynolds shear stress, and the effect of shear stress from velocity gradient near the wall is small. The optimum condition of vibration for drag reduction is also discussed in this paper.
New approach to magnetohydrodynamic stability. I. A practical stability concept

An equilibrium is called σ stable if growth faster than exp (σt) does not occur. On the basis of this definition a modified energy principle is obtained by means of which the stability of plasma confinement systems can be tested for times of thermonuclear interest, instead of the infinitely long times which are pertinent to the usual stability analysis. The theory is applied to the diffuse linear pinch, a theorem for σ stability is derived, and the connection with the normal‐mode analysis is shown to be given with the Sturmian property, which holds for the unstable side of the spectrum, whereas the stable side consists of Sturmian and anti‐Sturmian point spectra separated by continuous spectra. Growth rates and eigen‐functions of Suydam modes are numerically calculated, and it is shown that violation of Suydam's criterion in the high and intermediate shear case leads to nonlocalized rapidly growing m = 1 modes. Consequently, this criterion obtains new relevance in the σ‐stability analysis for this regime.