Miracle-dz/UniFAR-FTUs huggingface dataset:
A mathematical model for calculating effects of back corona in wire‐duct electrostatic precipitators

A new mathematical model for the electrical conditions in wire‐duct electrostatic precipitators is described. The model is based on the solution of Maxwell’s equations for the electric field components and offers several advantages over numerical solutions of Poisson’s equation. The model is used to calculate the effects of back corona on (1) the voltage‐current characteristic, (2) the current‐density distribution at the collector plate, and (3) particle collection for five simple mechanisms describing the generation of back corona. Each mechanism is capable of simulating the V‐I curves characteristic of precipitators operating in back corona, but two in particular are identified as potential back corona mechanisms on the basis of generating hysteresis in the V‐I curves or characteristic current density variations. These mechanisms are consistent with limited experimental data. This method of calculation is useful and can be extended to more complex mechanisms for back corona generation.
The luminosity function of the CfA Redshift Survey

We use the CfA Reshift Survey of galaxies with m(sub z) less than or equal to 15.5 to calculate the galaxy luminosity function over the range -13 less than or equal to M(sub z) less than or equal to -22. The sample includes 9063 galaxies distributed over 2.1 sr. For galaxies with velocities cz greater or equal to 2500 km per sec, where the effects of peculiar velocities are small, the luminosity function is well represented by a Schechter function with parameters phi(sub star) = 0.04 +/- 0.01 per cu Mpc, M(sub star) = -18.8 +/- 0.3, and alpha = -1.0 +/- 0.2. When we include all galaxies with cz greater or equal to 500 km per sec, the number of galaxies in the range -16 less than or equal to M(sub z) less than or equal to -13 exceeds the extrapolation of the Schechter function by a factor of 3.1 +/- 0.5. This faint-end excess is not caused by the local peculiar velocity field but may be partially explained by small scale errors in the Zwicky magnitudes. Even with a scale error as large as 0.2 mag per mag, which is unlikely, the excess is still a factor of 1.8 +/- 0.3. If real, this excess affects the interpretation of deep counts of field galaxies.
Two-dimensional hexagonal-shaped microcavities formed in a two-dimensional photonic crystal on an InP membrane

We present simulation and experimental results on hexagonal-shaped microcavities formed in two-dimensional (2D) photonic crystals (PC’s). The PC structures, realized with InP-based materials, are studied in two configurations : Air-suspended membranes (A type) and membranes supported by silica (S type). The optical properties of these microcavities are analyzed through photoluminescence experiments. Plane-wave expansion method calculations provide simulation results that are consistent with experimental data. The influence on spectral properties of various parameters, such as cavity size or air filling factor (f), is thoroughly analyzed, and their effect on resonator loss mechanisms is extracted, to give guidance for further PC laser improvement, e.g., threshold reduction.
Detection and Velocities of Hα Emission Regions in Stephan's Quintet

We present observations of Hα emission of Stephan's Quintet obtained with a scanning Fabry-Perot interferometer and samplings of ~11 km s-1 and ~1''. Our observations show an intragroup arclike feature formed of bright Hα knots and diffuse gas distributed along tidal tails associated with NGC 7318B and possibly also NGC 7318A. New velocities for 23 emitting regions detected along the Hα structure are presented. South of NGC 7318B, along a path covering ~12 h−175 kpc, H II regions with velocities ranging from 5540 to 6700 km s-1 are detected, suggesting that two or more overlapping tidal tails and/or a bow-shock region may have been formed through several interaction events within the group.
Texture-induced modulation noise and its impact on magnetic recording performance

The mechanical texturing of recording media which is necessary for good stiction characteristics can have an undesirable side effect on magnetic performance. A simple technique is described to measure the modulation noise caused by the texture in the substrate. Measurements made on CoPtCr media show a strong connection between the degree of modulation and the error rate. >
Comparison of Methods for Parameter Estimation in a Circular Linear Mixed Effect Model Incorporating the Diurnal Variation for Evaluating the Treatment Effects of Glaucoma Therapy

Glaucoma is the primary cause of vision loss in Japan. The most important glaucoma therapy is to decrease intraocular pressure (IOP) for preventing visual field defects in the pre-stage of vision loss. Considering a systematic diurnal variation of IOP, Kuwayama et al. (2006) proposed to use a circular linear mixed effect (CLME) model for evaluating the efficacy of therapy on IOP decrease for patients with normal tension glaucoma (NTG) and applied it to the data analysis in a clinical trial (Nipradilol trial) with 28 NTG patients. In this application, there occurred an issue that the parameter estimates were different depending on the method of estimation and the best method was not identified. We, therefore, compared six methods for parameter estimation (standard two-stage (STS) method, global two-stage (GTS) method, first order approximation (FOA) method, Laplacian approximation (LAP) method, Monte Carlo integration (MCI) method and Gaussian quadrature (GAUS) method) through a simulation experiment with the bias and square root of mean squared error as the criteria for evaluation. The GAUS method proved to be superior to others in realizing least bias and mean squared error under various simulation conditions, although it was most time consuming.
The integral cohomology rings of groups of order

0. Introduction. Most of the papers in cohomology of groups have been theoretical [1], [3]-[6], [8], [9], [13], [14], rather than computational. The following list describes all the (published and unpublished) computations I am aware of. Atiyah [1, p. 60] calculated the integral (cohomology) ring of the quaternion group Q of order 8. Wall [16] obtained the additive structure of split cyclic-by-cyclic extension. He could not get the ring structure. Cartan-Eilenberg [3, Chapter XII, §7] calculated the cohomology of a cyclic group with any coefficients, and gave an explicit diagonal map. Evens [6] wrote down the cohomology ring of the dihedral group D of order 8. Unfortunately, he did not publish the details of his calculations. Nakaoka [9] calculated the homology ring of symmetric groups with coefficients Zp and in [10, p. 52] found the cohomology ring of S4, coefficients Z2. Cardenas [2] calculated the ring of 2p2, coefficients Zp. Täte [15] got the integral homology ring of any finitely generated abelian group. Finally, Norman Hamilton and Arnold Shapiro got the integral cohomology ring of Zp I Zp, but neglected to write it down. In this paper, I will find the integral cohomology rings of groups of order /»3, except for Q and D. I merely sketch the abelian cases, as they are trivial. 1. Review of basic facts. 1.1. We recall some basic results on change of groups, transfer, and spectral sequences. Throughout this paper, all G-modules are left G-modules, all exact sequences of G-modules are assumed Z-split, and all groups are finite (in many places, this last assumption is superfluous). Let G, G' be groups, A, A' be G (resp. G')-modules. Definition. A change of groups </>: (G, A) -> (G', A') is a pair (<p, a) such that 9>: G' -*■ G is a morphism, and a: Aw -*■ A' is a G'-morphism. A change of groups </> induces a morphism </>*: Hn(G, A) -*■ Hn(G', A'), «50. </>* is obtained as follows: Let I be a G-projective resolution of Z, Ta G'-projective resolution of Z. The comparison theorem gives a homotopy class of chain maps Y1+ Xw. For £ e Hn(G, A), with representative cocycle A: Xn -> A, we let ç6*(A) be the image of incl A e HomG (X, A) -► HomG. (Xw, Aw) f* «* _ -> HomG. ( Y, Aw) -> HomG-(T, A') Received by the editors October 21, 1966. C) This research was done when the author was an NSF Graduate Fellow. 501
An analysis of the effect of entrainment temperature on jet impingement heat transfer

Developpement d'un modele analytique pour la determination de l'influence de la temperature du fluide entraine sur le transfert de chaleur local d'une surface a un jet d'air bidimensionnel qui vient la frapper. Comparaison du modele avec des mesures de transfert de chaleur effectuees sur des ensembles de jets demontrant la validite du modele
Vibration Control to Avoid Stick-Slip Motion

Friction-induced self-sustained oscillations result in a very robust limit cycle that characterizes stick-slip motion. This type of motion should be avoided under any circumstances because it creates noise, wear, and damage. In this paper we show, by simple models, how stick-slip motion can be avoided. Effective methods are: (i) appropriate increase of internal damping that compensates the negative damping induced by a friction characteristic, which decreases with increasing sliding speed; (ii) external excitation that breaks up the limit cycle (however, this often leads to chaotic motion); (iii) passive vibration control by fluctuating normal forces. The last mentioned mechanism is new and will be investigated in detail. The stick-slip oscillator is extended by an additional degree of freedom, which couples the slipping motion to the normal force. The dynamic behavior of the system has been worked out by analytical investigations and numerical integration. Scanning a broad range of values, parameters of the additional system, called the dynamic vibration absorber, have been found that prevent stick-slip and minimize the amplitude of the residual limit cycle. For this task the evaluation of the system behavior has been achieved by observing its energy content. The feasibility of the proposed dynamic vibration absorber is demonstrated by an experiment.
A boundary integral equation for Calderón's inverse conductivity problem

Towards a constructive method to determine an L1-conductivity from the corresponding Dirichlet to Neumann operator, we establish a Fredholm integral equation of the second kind at the boundary of a two dimensional body. We show that this equation depends directly on the measured data and has always a unique solution. This way the geometric optics solutions for the L1-conductivity problem can be determined in a stable manner at the boundary and outside of the body.
Propagation of a sudden impulse through the magnetosphere initiating magnetospheric Pc5 pulsations

[1] We compare multipoint observations of an interplanetary shock’s interaction with the Earth’s magnetosphere on 29 July 2002 with results from global MHD simulations. The sudden impulse associated with the shock’s arrival initiates global ultralow‐frequency waves with periods from 2 to 5 min. We interpret four cycles of Bz oscillations with T= ∼3 min at Geotail in the postdawn magnetosphere as radial magnetopause oscillations. GOES 8, in the same late morning sector, observed compressional and toroidal waves with the same frequency at the same time. GOES 10, in the early morning sector, observed toroidal waves with a slightly lower period. We suggest that these observations confirm the mode coupling theory. The interplanetary shock initiates compressional magnetospheric waves which, according to our estimates, oscillate between the ionosphere and magnetopause and gradually convert their energy into that of standing Alfven waves. At the same time, Polar in the outer predawn magnetosphere observed strong velocity oscillations and weak magnetic field oscillations with a ∼4 min period. Global MHD models successfully predict these oscillations and connect them to the Kelvin‐Helmholtz instability which results in large flow vortices with sizes of about ten Earth radii. However, the global models do not predict the multiple compressional oscillations with the observed periods and therefore cannot readily explain the GOES observations.
Classes of Graded Ideals with Given Data in the Exterior Algebra

Let ℱ be the family of graded ideals J in the exterior algebra E of a n-dimensional vector space over a field K such that e(E/J) = dim K (E/J) = e, indeg(E/J) = i and H E/J (i) = dim K (E/J) i are fixed integers. It is shown that there exists a unique lexsegment graded ideal J(n, e, i) ∈ ℱ whose Betti numbers give an upper bound for the Betti numbers of the ideals of ℱ. The authors continue the computation of upper bounds for the Betti numbers of graded ideals with given data started in Crupi and Utano (1999).
The impact of Omega dropwindsondes on operational hurricane track forecast models

Abstract Since 1982, the Hurricane Research Division (HRD) has conducted a series of experiments with research aircraft to enhance the number of observations in the environment and the core of hurricanes threatening the United States. During these experiments, the National Oceanic and Atmospheric Administration WP-3D aircraft crews release Omega dropwindsondes (ODWs) at 15–20-min intervals along the flight track to obtain profiles of wind, temperature, and humidity between flight level and the sea surface. Data from the ODWs are transmitted back to the aircraft and then sent via satellite to the Tropical Prediction Center and the National Centers for Environmental Prediction (NCEP), where the observations become part of the operational database. This paper tests the hypothesis that additional observations improve the objective track forecast models that provide operational guidance to the hurricane forecasters. The testing evaluates differences in forecast tracks from models run with and without the ODW d.
Heat Transfer in Trailing Edge Wedge-Shaped Pin-Fin Channels With Slot Ejection Under High Rotation Numbers

The heat transfer characteristics of a rotating pin-fin roughened wedge shaped channel have been studied. The model incorporates ejection through slots machined on the narrower end of the wedge, simulating a rotor blade trailing edge. The copperplate regional average method is used to determine the heat transfer coefficient; pressure taps have been used to estimate the flow discharged through each slot. Tests have been conducted at high rotation (≈ 1 ) and buoyancy (≈ 2) numbers, in a pressurized rotating rig. Reynolds Numbers investigated range from 10,000 to 40,000 and rotational speeds range from 0–400rpm. Pin-fins studied are made of copper as well as non-conducting garolite. Results show high heat transfer coefficients in the proximity of the slot. A significant enhancement in heat transfer due to the pin-fins, compared with a smooth channel is observed. Even the non-conducting pin-fins, indicative of heat transfer on the end-wall show a significant enhancement in the heat transfer coefficient. Results also show a strong rotation effect, increasing significantly the heat transfer coefficient on the trailing surface — and reducing the heat transfer on the leading surface.Copyright © 2010 by ASME
Symmetry Groups of Boolean Functions and Constructions of Permutation Groups

In this paper we deal with the symmetry groupS(f) of a boolean functionfonn-variables, that is, the set of all permutations onnelements which leavefinvariant. The main problem is that of concrete representation: which permutation groups onnelements can be represented asG = S(f) for somen-ary boolean functionf. Following P. Clote and E. Kranakis [6] we consider, more generally, groups represented in such a way byk-valued boolean functions (i.e., functions on a two-element set withkpossible values) and call such permutation groupsk-representable (k ≥ 2). The starting point of this paper is a false statement in one of the theorems of [6] that everyk-representable permutation group is 2-representable for allk ≥ 2. We show that there exists a 3-representable permutation group that is not 2-representable. A natural question arises whether there are other examples like this. This question turns out to be not easy and leads us to considering general constructions of permutation groups and investigating their properties. The main result of the present paper may be summarized as follows: using known groups and “standard” constructions no other example like that above can be constructed. Nevertheless, we conjecture that there arek + 1-representable permutation groups that are notk-representable for allk ≥ 2. If this is true, then this would open an interesting avenue toward investigating and classifying finite permutation groups.
Nonthermal X-ray emission from winds of OB supergiants

The mechanisms responsible for the hard X-ray emission of OB supergiants (OBSGs) are investigated theoretically, modifying the periodic-shock model of Lucy (1982). The physical processes discussed include (1) the particle acceleration (PA) mechanism and its effect on the structure of individual shocks, (2) the energy cutoff and spectral index of the relativistic electrons and ions, and (3) the efficiency of PA by shocks and its implications for the number densities of relativistic particles. The model is used to predict the spectrum and intensity of the dominant nonthermal X-ray emission source from OBSGs, and the results are shown to be in good agreement with Einstein Observatory Solid-State Spectrometer observations of three OBSGs in Orion (Cassinelli and Swank, 1983). It is inferred that the surface magnetic fields of OBSGs are no greater than a few G, and that the PA rates are significantly lower than generally predicted for collisionless astrophysical shocks. 66 refs.
For the inf‐sup condition on mesh‐dependent norms on a nonconvex polygon

It is shown that the inf‐sup condition, called the Babuska–Brezzi condition, is valid for certain mesh‐dependent norms on a nonconvex polygonal domain. A bilinear form that is derived by inserting the corner singularity expansion into the Laplace equation is considered. A mesh‐dependent fractional norm related to the least order of the corner singularity at a concave vertex is considered. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008
The role of NiAl underlayers in longitudinal thin-film recording media

Longitudinal recording media made with chromium and with nickel-aluminum underlayers are compared. NiAl films have smaller grains and random crystallographic orientation, while Cr films have larger grains and either a {110} or a {200} preferred orientation depending on the deposition conditions. Cobalt alloy films grown on NiAl have nearly random crystallographic orientation and significant c-axis out-of-plane component, and lower hysteresis loop squareness and coercivity than films made on a heated Cr underlayer. NiAl-underlayer media do not exhibit in-plane magnetic anisotropy induced by the substrate texture lines. CoCrTaPt/Cr/NiAl media had higher overwrite than CoCrTaPt/Cr media due to higher coercive squareness and a sharper hysteresis loop closure.
Surface plasmon polariton based modulators and switches operating at telecom wavelengths

We report design, fabrication, and characterization of thermo-optic Mach–Zender interferometric modulators and directional-coupler switches whose operation utilizes the long-range surface-plasmon-polariton waveguiding along 15-nm-thin and 8-μm-wide gold stripes embedded in polymer and heated by electrical signal currents. The devices are characterized at the light wavelength of 1.55 μm, featuring low driving powers ( 30dB), moderate response times (∼1ms), and the total (fiber-to-fiber) insertion loss of ∼13dB (for modulators) and ∼11dB (for switches) when using single-mode fibers.
Numerical Model for Simulation of Pump-Intake Flow and Vortices

This paper describes the development of a computational fluid dynamics model to simulate the three-dimensional flow field in a pump intake and to study the formation of free-surface and wall-attached vortices. The model solves the Reynolds-averaged Navier-Stokes equations and two turbulence-model equations in generalized curvilinear coordinates using a fully implicit, fractional-step algorithm based on alternate direction implicit approximate factorization. A two-layer k-e turbulence model is employed to resolve the near-wall flow that is critical to the description of wall-attached vortices. Solutions at a Reynolds number of 60,000 for flow in a simple rectangular sump are presented to demonstrate the use of the numerical model to predict the location and strength of free-surface and wall-attached vortices. As the case study was selected according to commonly used design criteria, relatively weak vortices are predicted. The predicted complex vortex structure is analyzed. The test case suggests that the n.
Commentary on: Changes in Glucose Control and Lipid Levels Following Trunk-Based Body Contouring Surgery in Postbariatric and Nonbariatric Patients

The effect of weight loss and bariatric surgery on comorbidities is well documented. In this article, the authors look at the effects of trunk-based body contouring (BC) surgery on metabolic changes, specifically on glucose and lipid levels, in nonbariatric and bariatric surgery patients. 1 The results of the study can assist with preoperative patient counseling and highlight the need for further study in this area (Video)
Distribution Functions of Means of a Dirichlet Process

Let $\chi$ be a random probability measure chosen by a Dirichlet process on $(\mathbb{R}, \mathscr{B})$ with parameter $\alpha$ and such that $\int x\chi(dx)$ turns out to be a (finite) random variable. The main concern of this paper is the statement of a suitable expression for the distribution function of that random variable. Such an expression is deduced through an extension of a procedure based on the use of generalized Stieltjes transforms, originally proposed by the present authors in 1978.
Topology of helical fluid flow

Considering a coordinate-free formulation of helical symmetry rather than more traditional definitions based on coordinates, we discuss basic properties of helical vector fields and compare results from the literature obtained with other approaches. In particular, we discuss the role of the stream function for the topology of the streamline pattern in incompressible flows. On this basis, we perform a comprehensive study of the topology of the flow field generated by a helical vortex filament in an ideal fluid. The classical expression for the stream function obtained by Hardin (Hardin, J. C. 1982 Phys. Fluids25, 1949–1952) contains an infinite sum of modified Bessel functions. Using the approach by Okulov (Okulov, V. L. 1995 Russ. J.Eng. Thermophys.5, 63–75) we obtain a closed-form approximation which is considerably easier to analyse. Critical points of the stream function can be found from the zeroes of a single real function of one variable, and we show that three different flow topologies can occur, depending on a single dimensionless parameter. By including the self-induced velocity on the vortex filament by a localised induction approximation, the stream function is slightly modified and an extra parameter is introduced. In this setting two new flow topologies arise, but not more than two critical points occur for any combination of parameters.