Structural qualification testing and operational loading on a fiberglass rotor blade for the Mod-OA wind turbine

Fatigue tests were performed on full- and half-scale root end sections, first to qualify the root retention design, and second to induce failure. Test methodology and results are presented. Two operational blades were proof tested to design limit load to ascertain buckling resistance. Measurements of natural frequency, damping ratio, and deflection under load made on the operational blades are documented. The tests showed that all structural design requirements were met or exceeded. Blade loads measured during 3000 hr of field operation were close to those expected. The measured loads validated the loads used in the fatigue tests and gave high confidence in the ability of the blades to achieve design life

Effect of vortex generators on the power conversion performance and structural dynamic loads of the Mod-2 wind turbine

Applying vortex generators from 20 to 100 percent span of the Mod-2 rotor resulted in a projected increase in annual energy capture of 20 percent and reduced the wind speed at which rated power is reached by nearly 3 m/sec. Application of vortex generators from 20 to 70 percent span, the fixed portion of the Mod-2 rotor, resulted in a projected increase in annual energy capture of about half this. This improved performance came at the cost of a small increase in cyclic blade loads in below rated power conditions. Cyclic blade loads were found to correlate well with the change in wind speed during one rotor revolution

Higgs Boson Decay into a Pair of Leptons

The decay of a Higgs boson into a pair of W bosons h --> W^+W^-, is a dominant mode for Higgs boson masses above 135 GeV. At hadron colliders, searches for this decay focus on channels in which both W bosons decay leptonically into charged leptons, h --> W^+ W^- --> l^+ l^- plus missing energy. We show that semileptonic decays of heavy flavors are an important background to this signal. Lepton isolation provides too little suppression of heavy flavor contributions, and an additional 4 to 8 orders-of-magnitude suppression must come from physics cuts. An increase of the cut on the the minimum transverse momentum of non-leading leptons in multilepton events is one effective way to achieve the needed suppression, without appreciable loss of the Higgs boson signal.Comment: 4 pages, 2 figures, 1 table. AIP style file. Paper presented by Ed Berger. To be published in the proceedings of the 9th Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2006), Rio Grande, Puerto Rico, May 30-June 3, 200

A review of resonance response in large horizontal-axis wind turbines

Field operation of the Mod-0 and Mod-1 wind turbines is described. Operational experience shows that 1 per rev excitation exists in the drive train, high aerodynamic damping prevents resonance response of the blade flatwise modes, and teetering the hub substantially reduces the chordwise blade response to odd harmonic excitation. These results can be used by designer as a guide to system frequency placement. In addition it is found that present analytical techniques can accurately predict wind turbine natural frequencies

Crack growth measured on flat and curved surfaces at cryogenic temperatures

Multiple element continuity gage measures plane stress crack growth plus surface crack growth under plane strain conditions. The gage measures flat and curved surfaces and operates at cryogenic temperatures

Associated Higgs plus vector boson test of a fermiophobic Higgs boson

Production in association with an electroweak vector boson V is a distinctive mode of production for a Higgs boson H without tree-level couplings to fermions, known as a fermiophobic Higgs boson. We focus on HV associated production with H decay into a pair of photons, and V into a pair of jets, with the goal of distinguishing a fermiophobic Higgs boson from the standard model Higgs boson. Performing a simulation of the signal and pertinent QCD backgrounds, and using the same event selection cuts employed by the LHC ATLAS Collaboration, we argue that existing LHC data at 7 TeV with 4.9 fb^{-1} of integrated luminosity may distinguish a fermiophobic Higgs boson from a standard model Higgs boson near 125 GeV at about 1.9 standard deviation signal significance (1.9 sigma) per experiment. At 8 TeV we show that associated production could yield 2.8 sigma significance per experiment with 10 fb^{-1} of data.Comment: 5 pgs., 4 figs, version to appear in Phys. Rev.