Miracle-dz/UniFAR-FTUs huggingface dataset:
The optical jet of the galaxy NGC 4258: interaction with the interstellar medium

Monochromatic H-alpha and red continuum images, as well as high-resolution aperture synthesis C-12 maps, were obtained in order to study the optical jet of the spiral galaxy NGC 4258. The jet morphology shows strong interaction with the ambient interstellar medium. The optical emission of the jet is due to line emission arising possibly from gas of the ambient interstellar medium which has been entrained and shocked by the radio-emitting gas. The jet near the center is resolved and has a width of about 200 pc. The CO observations show two clouds on each side of the nucleus; these clouds outline a channel, and the H-alpha jet falls right into this channel. These observations are consistent with the jet being in or making a small angle with the galaxy plane. It is suggested that the channel represents a tunnel bored by energetic material and that jet activity in NGC 4258 has been intermittent in the recent past. The interstellar medium may play an important role in making jets detectable optically and in shaping their forms. 28 refs.
On fast multiplication of polynomials, the Fourier and Hartley transforms

We give a fast algorithm for multiplication of polynomials with real-valued coefficients without resort to complex numbers and the fast Fourier transformation. The efficiency of this algorithm is compared with the multiplication algorithm based on the discrete Hartley transformation. We demonstrate that the complexity of the Hartley transformation coincides, to within a linear term, with the complexity of the Fourier transformation, but the use of the Hartley transformation leads to a more efficient multiplication algorithm. We give analogues of these results for finite fields. In some cases, the multiplicative constants in bounds for the complexity of multiplication of polynomials and of the Fourier and Hartley transformations over finite fields are smaller than those in the case of the field of real numbers. This research was supported by the Russian Foundation for Basic Research, grant 99-01-01175, and the Federal Special Program Integration', grant 473.
Control of cavity tones using a spanwise cylinder

A detailed experimental study of flow over a deep cavity was conducted towards understanding the attenuation of tones using a spanwise cylinder. Two “no-control” cavities were compared with a similar configuration using a cylinder on the leading edge of the cavities. Parametric changes of the spanwise cylinder such as the distance from the wall are studied. Maximum control across the range of studied velocities occurs for a particular position of the spanwise cylinder for the two configurations. Reductions in sound pressure levels (SPL) of up to 36 dB were obtained. Moreover, a shaped cylinder was also studied and shows that the attenuation of tones is not due to high-frequency pulsing as suggested in the literature, but to an increase of the cavity-shear-layer thickness due to the change in the mean axial velocity profiles.PACS Nos.: 47.27. Rc, 47.27. Sd
On the formulation of boundary value problems with the incompressible constituents constraint in finite deformation poroelasticity

This paper considers the finite deformation theory of poroelasticity for the case in which a deformable solid constituent and an interpenetrating liquid constituent are each regarded as incompressible, and the mixing itself is regarded as taking place without the creation of voids. The resulting kinematical constraint gives rise to a Lagrange multiplier pressure in the resulting constitutive description. This pressure therefore enters into the separate momentum balance statements for each individual constituent. The formulation of boundary value problems in this context is well known in continuum mechanics. This paper examines how a systematic elimination of the Lagrange multiplier pressure from the mathematical formulation leads to a stress‐like tensor that generalizes a stress tensor concept introduced by Rajagopal and Wineman in the late 1980s, which they called the saturation stress. Here, by providing a rather complete development, it is discussed how boundary value problems are naturally formulated in terms of a single such stress tensor, how the constitutive theory is framed in terms of this stress tensor, and how certain questions concerning the formulation of boundary conditions are naturally addressed. Connections to the small deformation linear poroelastic (biphasic) theory are also provided. Copyright © 2012 John Wiley & Sons, Ltd.
Influence of member geometric imperfection on geometrically nonlinear buckling and seismic performance of suspen-dome structures

This paper focuses on the effect of member geometric imperfection on nonlinear geometrically buckling and seismic performance of a new style of space steel structure, suspen-dome, which is composed of a reticulated shell and cable-strut system. By supposing the initial curvature of members as half-wave sinusoids, a stiffness equation of imperfect truss elements is derived for the struts, while that of imperfect beam elements is derived for the reticulated shell members. The proposed imperfect elements are implanted into ANSYS finite element program. Three numerical examples are employed to validate the proposed imperfect elements and analysis method. An ellipsoidal suspen-dome of Changzhou gymnasium is taken as an example. The results show that the imperfection value has relatively great influence on the structural stiffness. With the increase of member imperfection, the critical load decreases in a basically linear way. Under different prestress states, the relation curves between the critical load and imperfection are basically parallel. The nonlinear seismic analysis results show that when imperfection is included, the initial state responses are different, namely, the seismic displacement increases while the stress in rods and cables decreases. The proposed imperfection analysis method can be widely used in not only suspen-dome structures, but also other kinds of prestressed space grid structures. In this way, the influence of member imperfection on structural buckling and seismic performance can be estimated.
The influence of wave breaking on the surface pressure distribution in wind—wave interactions

In reviewing the current status of our understanding of the mechanisms underlying wind-wave generation, it is apparent that existing theories and models are not applicable to situations where the sea surface is disturbed by breaking waves, and that the available experimental data on this question are sparse. In this context, this paper presents the results of a detailed study of the effects of wave breaking on the aerodynamic surface pressure distribution and consequent wave-coherent momentum flux, as well as its influence on the total wind stress. Two complementary experimental configurations were used to focus on the details and consequences of the pressure distribution over breaking waves under wind forcing. The first utilized a stationary breaking wave configuration and confirmed the presence of significant phase shifting, due to air flow separation effects, between the surface pressure and surface elevation (and slope) distributions over a range of wind speeds. The second configuration examined the pressure distribution, recorded at a fixed height above the mean water surface just above the crest level, over short mechanically triggered waves which were induced to break almost continuously under wind forcing. This allowed a very detailed comparison of the form drag for actively breaking waves and for waves of comparable steepness just prior to breaking (‘incipiently’ breaking waves). For these propagating steep-wave experiments, the pressure phase shifts and distributions closely paralleled the stationary configuration findings. Moreover, a large increase (typically 100%) in the total windstress was observed for the breaking waves, with the increase corresponding closely to the comparably enhanced form drag associated with the actively breaking waves. In addition to further elucidating some fundamental features of wind-wave interactions for very steep wind waves, this paper provides a useful data set for future model calculations of wind flow over breaking waves. The results also provide the basis for a parameterization of the wind input source function applicable for a wave field undergoing active breaking, an important result for numerical modelling of short wind waves.
Traps in germanium nanocrystal memory and effect on charge retention : Modeling and experimental measurements

Surface traps, or traps at the interface of the nanocrystal and the surrounding matrix, play an important role in the charge retention performance of nanocrystal memory transistors. In this article, we report the investigation of trap energy levels in nanocrystalline germanium (nc-Ge) memory transistor and capacitor structures and their effect on the device charging and discharging kinetics through theoretical modeling and experimental measurements. The theoretical model, calibrated using the experimental data, uses a self-consistent quantum-mechanical tunneling numerical approach for calculating the transmission coefficient across the tunnel barrier. The effect of the trap energy on charge retention is shown by temperature-dependent measurements on the nc-Ge memory structures. The trap energy-level requirement for achieving a specified long-term charge retention performance (i.e., 10-yr retention time) is obtained from simulation as a function of the nanocrystal size.
The Properties and Environment of the Giant, Infrared-Luminous Galaxy IRAS 09104+4109

IRAS 09104 + 4109 is the most luminous object yet discovered by means of the IRAS survey. It is identified with a cD galaxy having a strong emission-line spectrum at a redshift of 0.442 and emits 6 x 10 to the 12th solar luminosities/sq h, 99 percent of which emerges at infrared wavelengths. One component of a double radio source is coincident with the center of the galaxy. The high luminosity of this source may be related to an interaction with one or more members of the rich cluster in which it lies. There is a secondary peak in the emission-line image of the galaxy. Emission lines from both regions are broad but narrower than those characteristic of the only other objects known to have such high luminosities, such as Seyfert 1's and QSOs. It is suggested that the strong infrared excess of IRAS 09104 + 4109 is produced by dust obscuring a broad line region.
What fuzzy interval operations should be hardware supported?

An essential part of our knowledge is not formulated in well-defined mathematical terms. We humans have no problem processing this informal knowledge as long as there is a reasonably small amount of it. In many cases, there is a lot of such knowledge, and we need an automated way to process it. Such processing is called "soft computing". In particular, when this knowledge is about numbers (e.g., about the temperature inside the reactor), then "informal") means that we do not know the exact value. Instead, we have some ideas of what this number can be. For different values, we can have different degrees of belief that a particular value is possible. These degrees of belief can be represented as membership functions (fuzzy sets). The values of membership functions are not precisely known, so, to make this description more adequate, we must use membership function with interval values, i.e., interval fuzzy sets. Processing a function takes much longer than processing a number. How to make processing faster? A natural idea is to implement operations with fuzzy interval in hardware. At first glance, the solution is simple: take all the operations with real numbers that are hardware supported in the usual computers (they are all functions of one or two variables), and support similar fuzzy interval operations. In this paper, we prove that we also need hardware support of fuzzy interval operations with three (or maybe more) fuzzy operands. <<ETX>>
A novel scheme for fractal image coding

In traditional fractal image coding schemes, domain blocks are constrained to be twice as large as range blocks in order to ensure the convergence of the iterative decoding stage. However, this constraint has limited the fractal encoder to exploit the self-similarity of the original image. In order to overcome the shortcoming, a novel scheme using same sized range and domain blocks is proposed. Experimental results show the improvement in compression ratio and image quality.
Attitude Dynamics Identification of Unmanned Aircraft Vehicle

The role of Unmanned Aircraft Vehicles (UAVs) has been increasing significantly in both military and civilian operations. Many complex systems, such as UAVs, are difficult to model accurately because they exhibit nonlinearity and show variations with time. Therefore, the control system must address the issues of uncertainty, nonlinearity, and complexity. Hence, identification of the mathematical model is an important process in controller design. In this paper, attitude dynamics identification of UAV is investigated. Using the flight data, nonlinear state space model for attitude dynamics of UAV is derived and verified. Real time simulation results show that the model dynamics match experimental data.
Analysis of the cylindrical-rectangular patch antenna

An analysis is presented of a thin cylindrical-rectangular microstrip patch antenna. After obtaining the electric field under the curved patch and the resonant frequencies using the cavity model, the far-field is found by considering the equivalent magnetic current radiating in the presence of a cylindrical surface. The input impedance and the total Q-factor are then calculated. Numerical and graphical results are presented to illustrate the effect of curvature on the characteristics of the TM/sub 10/ and TM/sub 01/ modes. >
Acceleration and deceleration of coherent structures in the initial shear layers of laminar circular jets

The acceleration and deceleration of the shear layer mode coherent structures in the initial shear layers of two initially laminar subsonic circular air jets were measured by a novel method employing three hot-wires and the structure capturing scheme of the conditional sampling technique. Several modes of pairing, some of them axisymmetric and others involving tilted flow structures, were established and confirmed by flow visualization.
A New Catalogue of Galactic SNRs Corrected for Distance from the Galactic Plane

A new catalogue of 125 galactic SNRs is presented. A surface brightness-diameter relationship, corrected for variation in height I z I above the galactic plane, is derived and applied to the catalogue to yield I z I-corrected distances and diameters. A birth rate of about one every 30 or 40 years is indicated from the number-diameter diagram.
Nuclear and Particle Physics: An Introduction, 2nd edition, by B.R. Martin

covering some of the mathematical tools which helps one handle aperiodic systems. Overall, an excellent book despite a significant number of minor English errors, pitched, for me at least, at just the right level. Unfamiliar concepts are introduced gently with some nice historical background and one is not often weighed down by too much technical detail. For postgraduate researchers who may wish to familiarise themselves with the fascinating world of aperiodicity this is a must read.
Determining hypocentral parameters for local earthquakes in 1-D using a genetic algorithm

SUMMARY This paper introduces a powerful method for determining hypocentral parameters for local earthquakes in 1-D using a genetic algorithm (GA) and two-point ray tracing. Using existing algorithms to determine hypocentral parameters is difficult, because these parameters can vary based on initial velocity models. We developed a new method to solve this problem by applying a GA to an existing algorithm, HYPO-71. The original HYPO-71 algorithm was modified by applying two-point ray tracing and a weighting factor with respect to the takeoff angle at the source to reduce errors from the ray path and hypocentre depth. Artificial data, without error, were generated by computer using two-point ray tracing in a true model, in which velocity structure and hypocentral parameters were known. The accuracy of the calculated results was easily determined by comparing calculated and actual values. We examined the accuracy of this method for several cases by changing the true and modelled layer numbers and thicknesses. The computational results show that this method determines nearly exact hypocentral parameters without depending on initial velocity models. Furthermore, accurate and nearly unique hypocentral parameters were obtained, although the number of modelled layers and thicknesses differed from those in the true model. Therefore, this method can be a useful tool for determining hypocentral parameters in regions where reliable local velocity values are unknown. This method also provides the basic a priori information for 3-D studies.
A modified ensemble Kalman particle filter for non‐Gaussian systems with nonlinear measurement functions

The ensemble Kalman particle filter (EnKPF) is a combination of two Bayesian‐based algorithms, namely, the ensemble Kalman filter (EnKF) and the sequential importance resampling particle filter (SIR‐PF). It was recently introduced to address non‐Gaussian features in data assimilation for highly nonlinear systems, by providing a continuous interpolation between the EnKF and SIR‐PF analysis schemes. In this paper, we first extend the EnKPF algorithm by modifying the formula for the computation of the covariance matrix, making it suitable for nonlinear measurement functions (we will call this extended algorithm nEnKPF). Further, a general form of the Kalman gain is introduced to the EnKPF to improve the performance of the nEnKPF when the measurement function is highly nonlinear (this improved algorithm is called mEnKPF). The Lorenz '63 model and Lorenz '96 model are used to test the two modified EnKPF algorithms. The experiments show that the mEnKPF and nEnKPF, given an affordable ensemble size, can perform better than the EnKF for the nonlinear systems with nonlinear observations. These results suggest a promising opportunity to develop a non‐Gaussian scheme for realistic numerical models.
Studying exothermic reactions in the Ni-Al system at rapid heating rates using a nanocalorimeter

Heats of reaction and heat capacity changes were measured using scanning nanocalorimetry for a nickel and aluminum bilayer where initial heating rates of 104 K/s were achieved. Multiple exotherms were observed on the initial heating, but the number of intermediate exotherms decreased with increasing heating rate. The final phase was the B2 NiAl intermetallic. Results from the nanocalorimeter were compared with a conventional differential scanning calorimeter (operating at 0.7 K/s) to understand the effect of significant (10 000×) increases in heating rate on the phase transformation sequence. The high heating rate in the nanocalorimeter delays reaction initiation, causes the exothermic peaks to shift to higher temperatures, and appears to suppress the formation of intermediate, metastable phases. Potential explanations for this apparent suppression are discussed.
The structure of the turbulent Ekman layer

A mathematical model is employed for analysing the structure of the homogeneous ocean surface layer. The model is verified against laboratory measurements of the fully developed channel flow and the wind-induced channel flow. Turbulence models of different complexities are used and discussed. An extension of the k — e turbulence model to rotating flows is derived and tested. The study indicates that a suitably chosen constant eddy viscosity is adequate for predicting the velocity and shear stress distributions in the Ekman layer. For transport of different chemical and biological species it is, however, necessary to know the detailed transport properties of the layer. Non-dimensional vertical distributions of different turbulence quantities, characterizing the Ekman layer, are therefore predicted and analysed. Rotational effects in the turbulence model are found to somewhat change the shear stress distribution in the deeper parts of the boundary layer. DOI: 10.1111/j.2153-3490.1979. tb00913.x
SAW characteristics of sputtered aluminum nitride on silicon and gallium arsenide

A study was undertaken to evaluate the SAW properties of sputtered aluminum nitride on silicon and gallium arsenide substrates with different interface layers and different AlN film thickness. Thick (2.9 μm) AlN films were deposited on Si. The experimental results suggested that the SAW properties of the thick films were not improved as expected from theoretical consideration. The deviation from the theoretical prediction resulted from the degradation of the preferred orientation of the grains as the films grew thicker. Thinner films (1.0 μm) were then applied to Si, silicon-on-insulator (SOI), and GaAs wafers for studying the effect of substrate materials. Also multilayered metal and dielectric (MLM/D) structures were deposited on Si and GaAs substrates to evaluate the effect of these layers on the AlN. The experimental results showed that AlN SAW transducers fabricated on silicon substrates with a thin dielectric buffer layer provided the best performances. The buried oxide in the SOI substrate increased the velocity dispersion. The addition of MLM/D layers to the Si substrate also increased the velocity dispersion. The addition of MLM/D layers to GaAs slightly lowered the phase velocity but significantly increased the propagation loss. The AlN transducers fabricated on GaAs substrates without MLM/D layers gave the lowest propagation losses. The primary effect on the transducer losses is related to the film growth characteristics as evidenced by the x-ray data, surface morphology and grain orientation of the reactivity sputtered AlN films. The SAW velocity dispersion is controlled by the relation between the SAW velocities of films, layer and substrate materials
Extragalactic co: gas distributions which follow the light in IC 342 and NGC 6946

The CO emission in the two Scd galaxies, IC 342 and NGC 6946, has been mapped using the 14 m FCRAO telescope (HPBW = 50''). In each galaxy, the radial distribution of CO out to Rroughly-equal10 kpc exhibits a falloff which follows the exponential luminosity profile from the stellar disk. Neither galaxy shows a breach in the molecular gas like that found in our Galaxy between the nucleus and the molecular cloud annulus. The occurrence of this gap in our own Galaxy, but in neither of the external galaxies, suggests a possible link between the deficiency of gas and the presence of either a nuclear bulge or inner Lindblad resonance (ILR). From its rotation curve, the Milky Way has a large nuclear bulge and also has an ILR expected in the vicinity of the hole in the CO distribution. The CO rotation curves for IC 342 and NGC 6946 agree well with previous HI observations; at the present resolution these galaxies appear to undergo nearly rigid rotation inside R = 5 kpc and therefore have no ILRs and have small nuclear bulges. Further support for the association of the gap with ILR or bulge is provided by brief observations reportedmore » here of NGC 4321, a more distant Sc galaxy with a rotation curve similar to the Milky Way; the CO distribution appears like that in our own Galaxy with coarser resolution. « less