A Combination of WKNN to Fault Diagnosis of Rolling Element Bearings
Yaguo Lei, Zhengjia He, and Yanyang Zi
This paper presents a new method for fault diagnosis of rolling element bearings, which is developed based on a combination of weighted K nearest neighbor (WKNN) classifiers. This method uses wavelet packet transform based on the lifting scheme to preprocess the vibration signals before feature extr ... [J. Vib. Acoust. 131, 064502 (2009)] published Fri Nov 20, 2009.
Quantifying fatigue generated in high strain rate cyclic loading of Norway spruce
Ari Salmi, Lauri Salminen, and Edward Haeggstrom
Papermaking, especially mechanical pulping, consumes much energy. To reduce this energy consumption one has to understand and exploit the phenomena present during the pulping. An important phenomenon to understand is wood fatigue. We quantitatively measure the fatigue generated during high strain ra ... [J. Appl. Phys. 106, 104905 (2009)] published Fri Nov 20, 2009.
Random walker in temporally deforming higher-order potential forces observed in a financial crisis
Kota Watanabe, Hideki Takayasu, and Misako Takayasu
Basic peculiarities of market price fluctuations are known to be well described by a recently developed random-walk model in a temporally deforming quadratic potential force whose center is given by a moving average of past price traces [M. Takayasu, T. Mizuno, and H. Takayasu, Physica A 370, 91 (20 ... [Phys. Rev. E 80, 056110 (2009)] published Thu Nov 19, 2009.
Language structure in the n-object naming game
Adam Lipowski and Dorota Lipowska
We examine a naming game with two agents trying to establish a common vocabulary for n objects. Such efforts lead to the emergence of language that allows for an efficient communication and exhibits some degree of homonymy and synonymy. Although homonymy reduces the communication efficiency, it seem ... [Phys. Rev. E 80, 056107 (2009)] published Thu Nov 19, 2009.
Resonance, criticality, and emergence in city traffic investigated in cellular automaton models
A. Varas, M. D. Cornejo, B. A. Toledo, V. Munoz, J. Rogan et al.
The complex behavior that occurs when traffic lights are synchronized is studied for a row of interacting cars. The system is modeled through a cellular automaton. Two strategies are considered: all lights in phase and a green wave with a propagating green signal. It is found that the mean velocity ... [Phys. Rev. E 80, 056108 (2009)] published Thu Nov 19, 2009.
Topology-independent impact of noise on cooperation in spatial public goods games
Attila Szolnoki, Matjaz Perc, and Gyorgy Szabo
We study the evolution of cooperation in public goods games on different regular graphs as a function of the noise level underlying strategy adoptions. We focus on the effects that are brought about by different group sizes of public goods games in which individuals participate, revealing that large ... [Phys. Rev. E 80, 056109 (2009)] published Thu Nov 19, 2009.
A New Rotor-Ball Bearing-Stator Coupling Dynamics Model for Whole Aero-Engine Vibration
G. Chen
In this paper, a new rotor-ball bearing-stator coupling system dynamics model is established for simulating the practical whole aero-engine vibration. The main characteristics of the new model are as follows: (1) the coupling effect between rotor, ball bearing, and stator is fully considered; (2) th ... [J. Vib. Acoust. 131, 061009 (2009)] published Thu Nov 19, 2009.
Flow Physics of a Race Car Wing With Vortex Generators in Ground Effect
Yuichi Kuya, Kenji Takeda, Xin Zhang, Scott Beeton, and Ted Pandaleon
This paper experimentally investigates the use of vortex generators for separation control on an inverted wing in ground effect using off-surface flow measurements and surface flow visualization. A typical racing car wing geometry is tested in a rolling road wind tunnel over a wide range of incidenc ... [J. Fluids Eng. 131, 121103 (2009)] published Thu Nov 19, 2009.
Experimental Aeroacoustic Studies on Improved Tip Configurations for Passive Control of Noise Signatures in Low-Speed Axial Fans
Stefano Bianchi, Alessandro Corsini, Franco Rispoli, and Anthony G. Sheard
This paper presents the findings of an investigation on the use of several blade-tip configurations (modified by the addition of various end plates at the blade tip) for passive noise control in industrial fans. Utilizing an experimental technique developed to investigate noise sources along the rad ... [J. Vib. Acoust. 131, 061007 (2009)] published Wed Nov 18, 2009.
Effects of a Cracked Blade on Mistuned Turbine Engine Rotor Vibration
Akira Saito, Matthew P. Castanier, and Christophe Pierre
An efficient methodology for predicting the nonlinear forced vibration response of a turbine engine rotor with a cracked blade is presented and used to investigate the effects of the damage on the forced response. The influence of small random blade-to-blade differences (mistuning) and rotation on t ... [J. Vib. Acoust. 131, 061006 (2009)] published Wed Nov 18, 2009.
Multimode Dynamics and Out-of-Plane Drift in Suspended Cable Using the Kinematically Condensed Model
Lianhua Wang, Yueyu Zhao, and Giuseppe Rega
The large amplitude vibration and modal interactions of shallow suspended cable with three-to-three-to-one internal resonances are investigated. The quasistatic assumption and direct approach are used to obtain the condensed suspended cable model and the corresponding modulation equations for the ca ... [J. Vib. Acoust. 131, 061008 (2009)] published Wed Nov 18, 2009.
Nonlinear Free Vibration of a Symmetrically Conservative Two-Mass System With Cubic Nonlinearity
T. Pirbodaghi and S. Hoseini
In this study, the nonlinear free vibration of conservative two degrees of freedom systems is analyzed using the homotopy analysis method (HAM). The mathematical model of such systems is described by two second-order coupled differential equations with cubic nonlinearities. First, novel approximate ... [J. Comput. Nonlinear Dynam. 5, 011006 (2009)] published Wed Nov 18, 2009.
On Diluted-Fuel Combustion Issues in Burning Biogas Surrogates
David A. Wilson and Kevin M. Lyons
This paper describes an analysis of the burning velocity of pure and diluted fuels, with implications for the development and operation of biogas-fueled combustors. Background work in the area of flame stabilization and propagation are introduced from the combustion literature. Fuels examined in thi ... [J. Energy Resour. Technol. 131, 041802 (2009)] published Wed Nov 18, 2009.
Numerical Modeling of Heat Transfer and Pressure Losses for an Uncooled Gas Turbine Blade Tip: Effect of Tip Clearance and Tip Geometry
Lamyaa A. El-Gabry
A computational study has been performed to predict the heat transfer distribution on the blade tip surface for a representative gas turbine first stage blade. Computational fluid dynamics (CFD) predictions of blade tip heat transfer are compared with test measurements taken in a linear cascade, whe ... [J. Thermal Sci. Eng. Appl. 1, 022005 (2009)] published Wed Nov 18, 2009.
Influence of Gerotor Performance in Varied Geometrical Design Parameters
Chiu-Fan Hsieh
Gerotor performance is influenced by sealing properties, area efficiency, contact stress, and outlet pressure. This paper uses the hypotrochoidal curve to generate the gerotor profile, and adopts the curvature difference method to assess the sealing property and predict the stress on the rotor profi ... [J. Mech. Des. 131, 121008 (2009)] published Tue Nov 17, 2009.
Revising the simple measures of assortativity in complex networks
Xiao-Ke Xu, Jie Zhang, Junfeng Sun, and Michael Small
We find that traditional statistics for measuring degree mixing are strongly affected by superrich nodes. To counteract and measure the effect of superrich nodes, we propose a paradigm to quantify the mixing pattern of a real network in which different mixing patterns may appear among low-degree nod ... [Phys. Rev. E 80, 056106 (2009)] published Tue Nov 17, 2009.
Leakage mechanism in flat seals
F. Bottiglione, G. Carbone, L. Mangialardi, and G. Mantriota
We present a theoretical approach to estimate the fluid leakage in flat seals. The approach is based on the analogy between the seal-substrate interface and a porous medium. We assume that the interface is constituted of a random distribution of noncontact patches (the pores) and small but numerous ... [J. Appl. Phys. 106, 104902 (2009)] published Tue Nov 17, 2009.
Stabilization Method for Small-Bore Journal Bearings Utilizing Starved Lubrication
Hiromu Hashimoto and Masayuki Ochiai
This paper describes the stabilization method for small-bore circular journal bearings using starved lubrication. First, we describe the experimental examination to confirm the effect of supply oil conditions on stability of circular journal bearing by using a high-speed test rig. Then, the theoreti ... [J. Tribol. 132, 011703 (2009)] published Tue Nov 17, 2009.
Temporal structure and gain-loss asymmetry for real and artificial stock indices
Johannes Vitalis Siven and Jeffrey Todd Lins
Previous research has shown that for stock indices, the most likely time until a return of a particular size has been observed is longer for gains than for losses. We demonstrate that this so-called gain-loss asymmetry vanishes if the temporal dependence structure is destroyed by scrambling the time ... [Phys. Rev. E 80, 057102 (2009)] published Mon Nov 16, 2009.
Search and detection comparing midwave and longwave infrared
Tana Maurer, David L. Wilson, Stevie R. Smith, Dawne M. Deaver, Eric A. Flug et al.
To investigate the benefits of multiband infrared sensor design for target detection, search and detection experiments were conducted in the midwave infrared (MWIR) and longwave infrared (LWIR) wavebands in both rural and urban battlefields. In each battlefield environment, real imagery was collecte ... [Opt. Eng. 48, 116401 (2009)] published Mon Nov 16, 2009.
Zipf's Law in the Popularity Distribution of Chess Openings
Bernd Blasius and Ralf Tonjes
We perform a quantitative analysis of extensive chess databases and show that the frequencies of opening moves are distributed according to a power law with an exponent that increases linearly with the game depth, whereas the pooled distribution of all opening weights follows Zipf's law with univers ... [Phys. Rev. Lett. 103, 218701 (2009)] published Mon Nov 16, 2009.