Miracle-dz/UniFAR-FTUs huggingface dataset:
Influence of axial grooves in floating-ring-bearings on the nonlinear oscillations of turbocharger rotors

Turbochargers represent rotor systems with high rotation speed, low weight and low static load. They are usually supported in floating-ring bearings and subject to different nonlinear phenomena. Especially subsynchronous oscillations cause undesired acoustic effects in automotive applications. Numerical simulations are an economic and fast way to investigate the influence of different bearing parameters and geometries on the nonlinear oscillation behavior. Here, a coupled model is used in order to analyze the effect of axial grooves on the subsynchronous oscillations. The turbocharger rotor is modeled as a flexible multibody model. The hydrodynamic bearing forces and torques are calculated with a finite-element model. The pressure and sheer stress distributions in the oil films change due to the modified boundary conditions introduced by the grooves. Furthermore, the rotation of the rings and thus the position of the grooves has to be taken into account. Results of run-up simulations for a turbocharger rotor in full-floating-ring bearings are presented for both the plain cylindrical bearing and the bearing with axial grooves.
Tuning for Performance and Stability in Systems of Nearly Tautochronic Torsional Vibration Absorbers

This paper considers the dynamic response and performance characteristics of a special class of centrifugal pendulum torsional vibration absorbers. The absorbers of interest are designed by selection of the path that their center of mass follows, such that their dynamics are linear or nearly so, out to large amplitudes of motion, thereby avoiding the nonlinear-induced detuning that typically accompanies such responses. These order-tuned, tautochronic or isochronic, absorbers have been the subject of previous investigations, including analyses of the synchronous and certain nonsynchronous responses of systems comprised of a set of identical absorbers. The analysis and experiments have demonstrated that the synchronous response of such absorber systems can experience an instability that results in nonsynchronous responses in which a subset of absorbers have significantly larger amplitude than the corresponding synchronous response. In this study, we present results that generalize these stability results to include absorbers whose dynamics differ slightly from tautochronic by varying the absorber path such that both linear and nonlinear perturbations of perfect tuning are included. It is shown by analysis and verified by simulations that the perfect tuning case is quite special, specifically that the instability described above occurs for tunings very close to ideal and that the synchronous response can be made stable over the entire feasible operating range by employing small levels of linear and/or nonlinear detuning. Such detuning is known to have the additional benefit of resulting in smaller absorber responses and an attendant larger operating range albeit at the expense of absorber performance in terms of attenuating rotor torsional vibrations. The main conclusion of these results is that one can select a very small amount of detuning to avoid this undesirable instability and that such detuning does not have a significant effect on absorber effectiveness. The analytical results derived also provide a quantitative means of predicting synchronous absorber response amplitudes and the associated rotor torsional vibration levels, as well as the stability properties of these responses, results are very useful for the design of absorber systems.
Momentum of Light in a Refracting Medium.

It is pointed out that neither Minkowski’s nor Abraham’s proposal gives correctly the momentum density of light in a refracting medium. The correct result due to Peierls is simply derived. The imbalance of momentum flux at an interface corresponds to a force on the surface, and this is contrasted with a delayed force due to a finite beam width.
Analysis of differential GPS performance for marine users during solar maximum

GPS signals are refracted by the dispersive ionosphere, resulting in ranging errors dependent on both the given signal frequency and ionospheric total electron content. Such range errors translate into a degradation of positioning accuracies. While it is possible to mitigate the impact of ionospheric effects on GPS positioning applications through ionosphere modeling and/or differential techniques (DGPS), residual errors may persist in regions where steep gradients or localized irregularities in electron density exist, particularly during periods of high geomagnetic activity. Such effects are an issue for the reliable implementation of safety‐critical GPS systems. A solar maximum was observed in mid 2000 with associated degradations in GPS positioning accuracies. In this paper the impact of solar maximum on DGPS horizontal positioning applications is investigated. Analyses focus on determining limitations in horizontal positioning accuracies for operational marine DGPS systems. Long‐term analyses are conducted using data from permanent GPS reference networks in Canada, Brazil, and the United States. Several million observations are processed in this study during the years 1998–2000. Studies focus on large ionospheric gradients near the equatorial anomaly and at subauroral latitudes (associated with the main trough and storm‐enhanced densities). Results indicate that DGPS horizontal positioning accuracies are degraded by a factor of 2–5 relative to average values.
Optimal sample size allocation for tests with multiple levels of stress with extreme value regression

In this article, we discuss the optimal allocation problem in a multiple stress levels life‐testing experiment when an extreme value regression model is used for statistical analysis. We derive the maximum likelihood estimators, the Fisher information, and the asymptotic variance–covariance matrix of the maximum likelihood estimators. Three optimality criteria are defined and the optimal allocation of units for two‐ and k‐stress level situations are determined. We demonstrate the efficiency of the optimal allocation of units in a multiple stress levels life‐testing experiment by using real experimental situations discussed earlier by McCool and Nelson and Meeker. Monte Carlo simulations are used to show that the optimality results hold for small sample sizes as well. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007
Tropical Rainfall: A Comparison of Satellite-derived Rainfall Estimates with Model Precipitation Forecasts, Climatologies, and Observations

Abstract Quantitative estimates of rainfall, as derived from satellite observations of cloud-top temperature, have been produced for each 2.5° lat-long location from 30°N to 30°S for the period 1986–89. These remotely sensed estimates are a preliminary product of the Global Precipitation Climatology Project (GPCP), which is charged with the development of a global rainfall dataset during the period 1986–95, using all available in situ data supplemented with satellite-derived estimates of precipitation. Four-year means (1986–89) of monthly satellite-derived rainfall estimates were compared to the climatological rainfall datasets compiled by Jaeger and Legates and Willmott in the tropics, to assess the performance of the satellite estimates in the context of existing state-of-the-art global precipitation datasets. It is shown that the satellite estimates and the climatologies are in reasonable agreement both in temporal and spatial variation, although some large regional differences were found. A more quant.
THE COLD SHOULDER: EMISSION MEASURE DISTRIBUTIONS OF ACTIVE REGION CORES

The coronal heating mechanism for active region core loops is difficult to determine because these loops are often not resolved and cannot be studied individually. Rather, we concentrate on the “inter-moss” areas between loop footpoints. We use observations from the Hinode EUV Imaging Spectrometer and the X-Ray Telescope to calculate the emission measure distributions of eight inter-moss areas in five different active regions. The combined data sets provide both high- and low-temperature constraints and ensure complete coverage in the temperature range appropriate for active regions. For AR 11113, the emission can be modeled with heating events that occur on timescales less than the cooling time. The loops in the core regions appear to be close to equilibrium and are consistent with steady heating. The other regions studied, however, appear to be dominated by nanoflare heating. Our results are consistent with the idea that active region age is an important parameter in determining whether steady or nanoflare heating is primarily responsible for the core emission, that is, older regions are more likely to be dominated by steady heating, while younger regions show more evidence of nanoflares.
Gemini Multi-Object Spectrograph Observations of SCUBA Galaxies behind A851

We have identified counterparts to two submillimeter (submm) sources, SMM J09429+4659 and SMM J09431+4700, seen through the core of the z = 0.41 cluster A851. We employ deep 1.4 GHz observations and the far-infrared/radio correlation to refine the submm positions and then optical and near-infrared imaging to locate their counterparts. We identify an extremely red counterpart to SMM J09429+4659, while Gemini Multi-Object Spectrograph spectroscopy with Gemini North shows that the R = 23.8 radio source identified with SMM J09431+4700 is a hyperluminous infrared galaxy (LFIR ~ 1.5 × 1013 L☉) at z = 3.35, the highest spectroscopic redshift so far for a galaxy discovered in the submm. The emission-line properties of this galaxy are characteristic of a narrow-line Seyfert 1 galaxy, although the lack of detected X-ray emission in a deep XMM-Newton observation suggests that the bulk of the luminosity of this galaxy is derived from massive star formation. We suggest that active nuclei, and the outflows they engender, may be an important part of the evolution of the brightest submm galaxies at high redshifts.
COMPARATIVE STUDIES OF CLUSTERING PROPERTIES BETWEEN PASSIVE GALAXIES AND STAR-FORMING ONES

Using the volume-limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 6, we have explored the dependence of clustering properties of galaxies on the star formation activity. It is found that star-forming galaxies preferentially form isolated, close double and multiple systems, while passive galaxies preferentially inhabit the dense groups and clusters. We also construct the two samples with the same galaxy number and number density, and reach the same conclusion, which shows that our statistical conclusion is robust.
TM/sub 010/-mode microwave excited high power CO/sub 2/ laser using a cylindrical resonant cavity

Microwave discharges for excitation of CO/sub 2/ lasers have been investigated. A resonant microwave cavity (2.45 GHz) has been employed to get high power laser operation. Laser experiments using a system composed of axial fast gas flow, axial electric field, and axial laser beam have been performed. Homogeneous discharges have been obtained by a TM/sub 010/-mode cavity with reentrant type tuners on the both end plates. Calculations of the electric field inside the cylindrical cavity filled with a dielectric tube using the program SUPERFISH were compared with the results of the measurements. The laser output of 259 W and the efficiency of 14% (rf power to laser power conversion ratio) were obtained from a newly developed two-cavity CO/sub 2/ laser module. >
The thermal, magnetic, and structural characterization of the crystallization kinetics of Fe/sub 88/Zr/sub 7/B/sub 4/Cu/sub 1/, an amorphous soft magnetic ribbon

The characterization of the crystallization kinetics of an amorphous soft magnetic alloy, Fe/sub 88/Zr/sub 7/B/sub 4/Cu/sub 1/, called NANOPERM, is presented. Vibrating sample magnetometry (VSM), X-ray diffractometry, and differential scanning calorimetry have been used to observe crystallization kinetics. The VSM observations take advantage of the Curie temperature of the amorphous phase Tc-/sub amorphous/ of the NANOPERM alloy being below its primary crystallization temperature T/sub x1/. This allows for the volume of nanocrystals transformed in the crystallization process to be inferred magnetically, as well as thermally and structurally. The Johnson-Mehl-Avrami model for isothermal crystallization kinetics is compared with the Kissinger model for nonisothermal crystallization kinetics using data gathered from the three characterization methods. Linear regression and nonlinear regression analysis of crystallization data for NANOPERM ribbon and the significance of the values that describe them, namely, the activation energy Q and the morphology index n are investigated for isothermal and constant-heating crystallization. The activation energy for NANOPERM ribbon is presented here to be in the range of Q=2.8-3.4 eV, with the crystallization kinetics proceeding by three-dimensional diffusion and immediate nucleation, where the morphology index is n=1.5. A time constant to account for initial nonisothermal conditions during isothermal heating is introduced and determined to be T=120-200 s.
BVR photometry of comparison stars in selected blazar fields - I. Photometric sequences for 10 BL Lacertae objects

We present photometric sequences in the Johnson's BV and Cousins' R bands in the elds of 10 BL Lacertae objects (BL Lacs) monitored at the Torino Astronomical Observatory. Data were taken during 14 photometric nights from February 1995 to May 1997. The 56 calibrated stars are brighter than V = 16 and can be used as comparison objects in order to derive the BL Lac magnitudes. Finding charts are included for the stars iden- tication.
On the Eigenvalues of the Laplace Operator on a Thin Set with Neumann Boundary Conditions

Let Ω be open bounded set of IRn, whose boundary us of cluss C2 and let Ω(∞) be thcx set of whzch lic at a dtstance less than ∊ of Ω. CVt show that the p-th czqenvalue converges to the p-th eigenvalue λ of the Laplace-Beltrami oprator on δω. Ifλp Ap as sztnple, we give limit of . as ∊ tends to 0. These results are written zn thc language of analysis , and no knowledge of differntial geometry assumed.
Play or Work?: Generativity in Online Games

The digital multi-sided platform has led the growth of industries. Accelerating this growth, gen-erativity allowed innovation based on boundary-less modularity. Online games are a rich source of research but most of the research is dedicated in examining only the online game itself. However, there is a growing need to understand online games in an ecosystem level for a new phase of evolution is starting based on generativity. With generativity, online game users now make new graphics and quest that can be added and shared to the already existing game environment. The ecosystem is moving towards finding an amicable multi-sided distribution platform for these user generated game contents. Preliminary data suggest the possibility of actual connection between gen-erativity and users’ game engagement. Interviews and surveys will be prepared to find out the details of the possible relationship and how the ecosystem will shape accordingly.
PG 0922+162: Discovery of the Youngest Visual Double Degenerate

We recently discovered PG (WD) 0922+162 to be a visual double degenerate pair, the youngest found to date. Both components have effective temperatures just above 22,000 K, a region in which detailed fitting of the Balmer line profiles from high signal-to-noise spectra provides very accurate temperatures and gravities. Spatially resolved visual double degenerates can, in principle, be used to determine the initial-final mass (Mi-Mf) relation for white dwarfs. PG 0922+162 is the first resolved double degenerate for which the physical parameters may be derived with sufficient accuracy to improve on cluster results for the Mi-Mf relation. Using Wood's WD cooling models to determine the masses, our results are that the more luminous member of the pair, PG 0922+162 A, has Teff = 22,740 ± 230 K, log g = 8.27 ± 0.05, and M = 0.79 ± 0.03 M☉, while the fainter star, PG 0922+162 B, has Teff = 22,130 ± 220 K, log g = 8.78 ± 0.05, and M = 1.10 ± 0.03 M☉. The corresponding WD cooling times are about 90 and 260 Myr, respectively. Given the lack of an independent determination of the age of the system, we cannot directly obtain the progenitor mass for PG 0922+162 B. However, previous cluster results provide plausible limits to the progenitor mass for PG 0922+162 B of 5.5-7.5 M☉, which in turn limits the age of the PG 0922+162 system to the range of about 290-350 Myr. Given that age range, we find that the initial mass of the progenitor of PG 0922+162 A must lie within the narrow range of 3.6-4.0 M☉.
Statistical mechanics of uids at a permeable wall

eld imitating a permeable solid is considered. The cases of microand macroscopically smooth boundary are examined and the analysis of static membranes is performed within the framework of general consideration. Henry constant of adsorption and its connection with Henry constant of absorption, specic surface - potential (grand potential) and the surface number density are determined. High-temperature expansions for basic values are obtained. In the low-temperature limit it is shown that the results coincide with the previously considered problem of impermeable wall. \The surface tension coecient" decomposes into a value proportional to Henry constant of adsorption depending
Blind real-time low-complexity receivers for DS-CDMA mobile users

A new blind linear-filter receiver is proposed for the detection of DS-CDMA users in unknown multi-user interference and additive white Gaussian noise. The proposed receiver is motivated by the Wiener reconstruction-filter theory and it is a minimum-variance-distortionless-response-type filter that maximizes the output signal-to-interference-plus-noise-ratio. The receiver is randomized with input driven realizations and parametrized with respect to only a single scalar parameter. The batch solution for the single scalar tuning parameter is simple and requires no matrix inversion, while adaptive alternatives are fast, low-complexity, strongly consistent stochastic approximation recursions on R.
Strain–polarisation coupling and elastic constant determined from polarisation and strain curves in order–disorder uniaxial ferroelectrics

A practical method is developed to determine the strain dependence of the pseudospin–pseudospin interaction parameters in discrete models of the continuous order–disorder improper ferroelastic phase transitions from experimental data on the primary order parameter (polarisation). The temperature dependence of the mechanical strain can be then deduced from the spontaneous polarisation data only. It is also shown that the dependence of the elastic constant on the temperature can be obtained from the polarisation and the strain data. The temperature dependences of the coupling constant and the elastic constant between the molecular dipoles of the methylammonium ions in the uniaxial ferroelectrics (CH3NH3)5Bi2Cl11 (MAPCB) and (CH3NH3)5Bi2Br11 (MAPBB) are determined and shown to be at the origin of the particular shape of the polarisation and the strain curves.
Optimality of linear control systems

It is shown that every linear system with nondynamic feedback is optimal with respect to a quadratic performance index that includes a cross-product term between the state and control. If the index is further generalized to include derivatives of the control, every (sufficiently smooth) linear finite-dimensional dynamic feedback and feedforward control system is optimal. Methods of constructing all such indices are indicated, and some practical implications are discussed.
COMPARISON OF GALAXY CLUSTERS SELECTED BY WEAK-LENSING, OPTICAL SPECTROSCOPY, AND X-RAYS IN THE DEEP LENS SURVEY F2 FIELD

We compare galaxy clusters selected in Chandra and XMM-Newton X-ray observations of the 4 deg2 Deep Lens Survey (DLS) F2 field to the cluster samples previously selected in the same field from a sensitive weak-lensing shear map derived from the DLS and from a detailed galaxy redshift survey—the Smithsonian Hectospec Lensing Survey (SHELS). Our Chandra and XMM-Newton observations cover 1.6 deg2 of the DLS F2 field, including all 12 weak-lensing peaks above a signal-to-noise ratio of 3.5, along with 16 of the 20 SHELS clusters with published velocity dispersions >500 km s−1. We detect 26 extended X-ray sources in this area and confirm 23 of them as galaxy clusters using the optical imaging. Approximately 75% of clusters detected in either X-ray or spectroscopic surveys are found in both; these follow the previously established scaling relations between velocity dispersion, LX, and TX. A lower percentage, 60%, of clusters are in common between X-ray and DLS samples. With the exception of a high false-positive rate in the DLS weak-lensing search (5 out of 12 DLS candidates appear to be false), differences between the three cluster detection methods can be attributed primarily to observational uncertainties and intrinsic scatter between different observables and cluster mass.
Hexagonally ordered 100 nm period nickel nanowire arrays

The magnetic behavior of 100 nm period arrays of Ni nanowires embedded in a highly ordered alumina pore matrix were characterized by magnetometry and magnetic force microscopy. Reducing the diameter of the nanowires from 55 to 30 nm while keeping the interwire distance constant leads to increasing coercive fields from 600 to 1200 Oe and to increasing remanence from 30% to 100%. The domain structure of the arrays exhibits in the demagnetized state a labyrith-like pattern. These results show that stray field interactions of single domain nanowires are entirely dependent on the nanowire diameter.
Acceleration of cosmic rays in the solar wind termination shock. I. A steady state technique in a spherically symmetric model

In this paper, it is shown that a steady state model for the combined acceleration and modulation of cosmic rays in the heliosphere is possible. In this first of a series of papers, a spherically symmetric heliosphere with a termination shock at 50 AU is adopted. It is shown that the accelerated spectrum develops naturally from the shock boundary condition and that the low-energy source of particles to be accelerated need not be specified explicitly. The demonstration solutions on the shock are the expected power laws, and it is shown where shock curvature and acceleration time scale effects set in. Some of the basic features of the anomalous cosmic-ray component are explained by the solutions, but, as expected, a detailed comparison with observations must await more extensive and realistic models. 25 references.
The irrationality of certain infinite series

The aim of this paper is to prove the irrationality of a certain class of infinite series. The main theorem is related to some results due to Erdos and Straus [7], Erdos [5] and Sándor [15]. As applications of the main result, the solutions of two problems posed by Erdös and Graham [6] are given, among others.
Dynamics of the Outer Arm high-velocity cloud and the triaxiality of the Milky Way

Among high-velocity clouds of neutral hydrogen (HVCs) a so-called Outer Arm Cloud, often interpreted as a part of the general warp of the Milky Way disc, can be distinguished, which is located at 49° ≤ l ≤ 161° and 4° ≤ b ≤ 31° and has quite smooth velocity variation along its length. Closer inspection of the arm shows that its velocity field can be explained in two ways: (i) gas is moving in a circular orbit around the Galactic Centre, but the Sun has a galactocentric radial velocity component with respect to the Local Standard of Rest (LSR) of 28.5 km/s rather than -9.2 km/s as usually accepted; (ii) gas is moving in an elliptic orbit around the Glactic Centre