Enhancement of cooperation in highly clustered scale-free networks
Salvatore Assenza, Jesus Gomez-Gardenes, and Vito Latora
We study the effect of clustering on the organization of cooperation by analyzing the evolutionary dynamics of the Prisoner's Dilemma on scale-free networks with a tunable value of clustering. We find, on the one hand, that a high value of the clustering coefficient produces an overall enhancement o ... [Phys. Rev. E 78, 017101 (2008)] published Thu Jul 3, 2008.
Path integral approach to closed-form option pricing formulas with applications to stochastic volatility and interest rate models
D. Lemmens, M. Wouters, J. Tempere, and S. Foulon
We present a path integral method to derive closed-form solutions for option prices in a stochastic volatility model. The method is explained in detail for the pricing of a plain vanilla option. The flexibility of our approach is demonstrated by extending the realm of closed-form option price formul ... [Phys. Rev. E 78, 016101 (2008)] published Thu Jul 3, 2008.
Robust Multivariable Pitch Control Design for Load Reduction on Large Wind Turbines
M. Geyler and P. Caselitz
This paper deals with multivariable pitch control design for wind turbines, including load reducing control objectives. Different design approaches, including collective and cyclic pitch, and robustness aspects are discussed. A control design with decoupled controllers for collective and cyclic pitc ... [J. Sol. Energy Eng. 130, 031014 (2008)] published Thu Jul 3, 2008.
A Review of H[sub [infinity]] Robust Control of Piezoelectric Smart Structures
Lucian Iorga, Haim Baruh, and Ioan Ursu
Robust vibration control of piezoelectric actuated smart structures has attracted substantial interest in recent years. Such control laws are desirable for systems where guaranteed stability or performance is required despite the presence of multiple sources of uncertainty. In this work, we review t ... [Appl. Mech. Rev. 61, 040802 (2008)] published Thu Jul 3, 2008.
Energy efficiency in the built environment
Leon R. Glicksman
Policymakers, commercial enterprises, and scientists have focused increased attention over the past few years on the issue of energy. Of primary concern is the increase of atmospheric carbon dioxide from fossil-fuel consumption, which leads to global warming. National security is an additional conce ... [Phys. Today 61, 35 (2008)] published Wed Jul 2, 2008.
Social networks link interdisciplinary scientists
Jermey N. A. Matthews
Ten years ago newly hired mathematical physicist Jennifer Chayes told her boss, Microsoft Corp founder Bill Gates, about new methods, derived from the phase-transition theory of spin glasses, to solve constraint-satisfaction problems in social and other networks. She warned him, however, that they w ... [Phys. Today 61, 22 (2008)] published Wed Jul 2, 2008.
Model for the Lateral Behavior of Reinforced Concrete Columns Including Shear Deformations
Eric J. Setzler and Halil Sezen
This research is focused on modeling the behavior of reinforced concrete columns subjected to lateral loads. Deformations due to flexure, reinforcement slip, and shear are modeled individually using existing and new models. Columns are classified into five categories based on a comparison of their p ... [Earthquake Spectra 24, 493 (2008)] published Wed Jul 2, 2008.
Adaptive Pitch Control of Variable-Speed Wind Turbines
Kathryn E. Johnson and Lee Jay Fingersh
The aerodynamic efficiency of a variable-speed wind turbine operating in Region 2, or below-rated wind speeds, is greatly affected by the identification of accurate parameters for the controller. In particular, the power coefficient (C) surface must be well known for optimal efficiency to be achieve ... [J. Sol. Energy Eng. 130, 031012 (2008)] published Wed Jul 2, 2008.
Statistical Extrapolation Methods for Estimating Wind Turbine Extreme Loads
Patrick Ragan and Lance Manuel
With the introduction of the third edition of the International Electrotechnical Commission (IEC) Standard 61400-1, designers of wind turbines are now explicitly required, in one of the prescribed load cases, to use statistical extrapolation techniques to determine nominal design loads. In this stud ... [J. Sol. Energy Eng. 130, 031011 (2008)] published Wed Jul 2, 2008.
The Influence of the Joint Wind-Wave Environment on Offshore Wind Turbine Support Structure Loads
Puneet Agarwal and Lance Manuel
Our objective here is to establish long-term loads for offshore wind turbines using a probabilistic approach. This can enable one to estimate design loads for a prescribed level of return period, generally on the order of 2050 years for offshore wind turbines. In a probabilistic approach, one first ... [J. Sol. Energy Eng. 130, 031010 (2008)] published Wed Jul 2, 2008.
Apparatus for material tests using an internal loading system in high-pressure gas at room temperature
M. Imade, S. Fukuyama, and K. Yokogawa
A new type of apparatus for material tests using an internal loading system in high-pressure gas up to 100 MPa at room temperature without conventional material testing equipment was developed. The apparatus consists of a high-pressure control system and a pressure vessel, in which a piston is inst ... [Rev. Sci. Instrum. 79, 073903 (2008)] published Wed Jul 2, 2008.
From First Principles--Gauging the Web's Impact on Scientific Journals
Charles Day
... [Comput. Sci. Eng. 10, 96 (2008)] published Tue Jul 1, 2008.
Exposing Fortran Derived Types to C and Other Languages
Alexander Pletzer, Douglas McCune, Stefan Maszala, Srinath Vadlamani, and Scott Kruger
When building large scientific codes, you might have to mix different programming languages. The authors show how to bridge the interoperability gap between Fortran 90/95 and C, and from C to other languages, with working code examples. ... [Comput. Sci. Eng. 10, 86 (2008)] published Tue Jul 1, 2008.
Automatic Generation of Matlab Functions Using Mathematica and Thermath
Raquel S. Macedo, Marcelo F. Alfradique, and Marcelo Castier
The program tool Thermath now lets researchers automatically generate complete, ready-to-use Matlab functions. The examples here deal with critical-point calculations and the development of equipment models for separations in the chemical industry, but the ability to automatically generate Matlab fu ... [Comput. Sci. Eng. 10, 41 (2008)] published Tue Jul 1, 2008.
Uncertainty Analysis in MCP-Based Wind Resource Assessment and Energy Production Estimation
Matthew A. Lackner, Anthony L. Rogers, and James F. Manwell
This paper presents a mathematical framework to properly account for uncertainty in wind resource assessment and wind energy production estimation. A meteorological tower based wind measurement campaign is considered exclusively, in which measure-correlate-predict is used to estimate the long-term w ... [J. Sol. Energy Eng. 130, 031006 (2008)] published Tue Jul 1, 2008.
Multi-Scale Approach to the Fatigue Crack Propagation in High-Strength Pearlitic Steel Wires
J. Toribio, B. Gonzalez, J. C. Matos, and F. J. Ayaso
This paper deals with the influence of the manufacturing process on the fatigue behavior of pearlitic steels with different degrees of cold drawing. The fatigue crack growth rate (da/dN) is related to the stress intensity range (DeltaK) by means a compliance method to evaluate the crack depth a in t ... [J. ASTM Int. 5, 101564 (2008)] published Mon Jun 30, 2008.
Decelerating Microdynamics Can Accelerate Macrodynamics in the Voter Model
Hans-Ulrich Stark, Claudio J. Tessone, and Frank Schweitzer
For the voter model, we study the effect of a memory-dependent transition rate. We assume that the transition of a spin into the opposite state decreases with the time it has been in its current state. Counterintuitively, we find that the time to reach a macroscopically ordered state can be accelera ... [Phys. Rev. Lett. 101, 018701 (2008)] published Mon Jun 30, 2008.