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Arabidopsis Thaliana--Myzus Persicae Interaction: Shaping the Understanding of Plant Defense Against Phloem-Feeding Aphids (open access)

Arabidopsis Thaliana--Myzus Persicae Interaction: Shaping the Understanding of Plant Defense Against Phloem-Feeding Aphids

This review article summarizes recent studies that have exploited the compatible interaction between Arabidopsis and the green peach aphid (GPA) to understand the molecular and physiological mechanisms utilized by plants to control aphid infestation, as well as genes and mechanisms that contribute to susceptibility.
Date: July 1, 2013
Creator: Louis, Joe & Shah, Jyoti
System: The UNT Digital Library
ASME Material Challenges for Advanced Reactor Concepts (open access)

ASME Material Challenges for Advanced Reactor Concepts

This study presents the material Challenges associated with Advanced Reactor Concept (ARC) such as the Advanced High Temperature Reactor (AHTR). ACR are the next generation concepts focusing on power production and providing thermal energy for industrial applications. The efficient transfer of energy for industrial applications depends on the ability to incorporate cost-effective heat exchangers between the nuclear heat transport system and industrial process heat transport system. The heat exchanger required for AHTR is subjected to a unique set of conditions that bring with them several design challenges not encountered in standard heat exchangers. The corrosive molten salts, especially at higher temperatures, require materials throughout the system to avoid corrosion, and adverse high-temperature effects such as creep. Given the very high steam generator pressure of the supercritical steam cycle, it is anticipated that water tube and molten salt shell steam generators heat exchanger will be used. In this paper, the ASME Section III and the American Society of Mechanical Engineers (ASME) Section VIII requirements (acceptance criteria) are discussed. Also, the ASME material acceptance criteria (ASME Section II, Part D) for high temperature environment are presented. Finally, lack of ASME acceptance criteria for thermal design and analysis are discussed.
Date: July 1, 2013
Creator: Sabharwall, Piyush & Siahpush, Ali
System: The UNT Digital Library
Assessing Fatigue and Ultimate Load Uncertainty in Floating Offshore Wind Turbines Due to Varying Simulation Length (open access)

Assessing Fatigue and Ultimate Load Uncertainty in Floating Offshore Wind Turbines Due to Varying Simulation Length

With the push towards siting wind turbines farther offshore due to higher wind quality and less visibility, floating offshore wind turbines, which can be located in deep water, are becoming an economically attractive option. The International Electrotechnical Commission's (IEC) 61400-3 design standard covers fixed-bottom offshore wind turbines, but there are a number of new research questions that need to be answered to modify these standards so that they are applicable to floating wind turbines. One issue is the appropriate simulation length needed for floating turbines. This paper will discuss the results from a study assessing the impact of simulation length on the ultimate and fatigue loads of the structure, and will address uncertainties associated with changing the simulation length for the analyzed floating platform. Recommendations of required simulation length based on load uncertainty will be made and compared to current simulation length requirements.
Date: July 1, 2013
Creator: Stewart, G.; Lackner, M.; Haid, L.; Matha, D.; Jonkman, J. & Robertson, A.
System: The UNT Digital Library
Autonomous Vehicles Have a Wide Range of Possible Energy Impacts (Poster) (open access)

Autonomous Vehicles Have a Wide Range of Possible Energy Impacts (Poster)

This poster presents initial estimates of the net energy impacts of automated vehicles (AVs). Automated vehicle technologies are increasingly recognized as having potential to decrease carbon dioxide emissions and petroleum consumption through mechanisms such as improved efficiency, better routing, lower traffic congestion, and by enabling advanced technologies. However, some effects of AVs could conceivably increase fuel consumption through possible effects such as longer distances traveled, increased use of transportation by underserved groups, and increased travel speeds. The net effect on petroleum use and climate change is still uncertain. To make an aggregate system estimate, we first collect best estimates for the energy impacts of approximately ten effects of AVs. We then use a modified Kaya Identity approach to estimate the range of aggregate effects and avoid double counting. We find that depending on numerous factors, there is a wide range of potential energy impacts. Adoption of automated personal or shared vehicles can lead to significant fuel savings but has potential for backfire.
Date: July 1, 2013
Creator: Brown, A.; Repac, B. & Gonder, J.
System: The UNT Digital Library
Bioenergy market competition for biomass: A system dynamics review of current policies (open access)

Bioenergy market competition for biomass: A system dynamics review of current policies

There is growing interest in the United States and abroad to increase the use of biomass as an energy source due to environmental and energy security benefits. In the United States, the biofuel and biopower industries are regulated by different policies and different agencies and have different drivers, which impact the maximum price the industries are willing to pay for biomass. This article describes a dynamic computer simulation model that analyzes future behavior of bioenergy feedstock markets based on varying policy and technical options. The model simulates the long-term dynamics of these markets by treating advanced biomass feedstocks as a commodity and projecting the total demand of each industry, as well as the market price over time. The model is used for an analysis of the United States bioenergy feedstock market that projects supply, demand, and market price given three independent buyers: domestic biopower, domestic biofuels, and foreign exports. With base-case assumptions, the biofuels industry is able to dominate the market and meet the federal Renewable Fuel Standard (RFS) targets for advanced biofuels. Further analyses suggest that United States bioenergy studies should include estimates of export demand for biomass in their projections, and that GHG-limiting policy would partially shield both …
Date: July 1, 2013
Creator: Jacobson, Jacob J. & Jeffers, Robert
System: The UNT Digital Library
Charged-Particle Multiplicities in $Pp$ Interactions at $\sqrt{s}=900$ GeV Measured with the ATLAS Detector at the LHC (open access)
The CJ12 parton distributions (open access)

The CJ12 parton distributions

Three new sets of next-to-leading order parton distribution functions (PDFs) are presented, determined by global fits to a wide variety of data for hard scattering processes. The analysis includes target mass and higher twist corrections needed for the description of deep-inelastic scattering data at large x and low Q^2, and nuclear corrections for deuterium targets. The PDF sets correspond to three different models for the nuclear effects, and provide a more realistic uncertainty range for the d quark PDF compared with previous fits. Applications to weak boson production at colliders are also discussed.
Date: July 1, 2013
Creator: Accardi, Alberto & Owens, Jeff F.
System: The UNT Digital Library
Constitutive Modeling of High Temperature Uniaxial (open access)

Constitutive Modeling of High Temperature Uniaxial

Inconel Alloy 617 is a high temperature creep and
Date: July 1, 2013
Creator: Pritchard, P.G.; Carroll, L.J. & Hassan, T.
System: The UNT Digital Library
Constitutive Modeling of High Temperature Uniaxial Creep-Fatigue and Creep-Ratcheting Responses of Alloy 617 (open access)

Constitutive Modeling of High Temperature Uniaxial Creep-Fatigue and Creep-Ratcheting Responses of Alloy 617

Inconel Alloy 617 is a high temperature creep and corrosion resistant alloy and is a leading candidate for use in Intermediate Heat Exchangers (IHX) of the Next Generation Nuclear Plants (NGNP). The IHX of the NGNP is expected to experience operating temperatures in the range of 800 degrees - 950 degrees C, which is in the creep regime of Alloy 617. A broad set of uniaxial, low-cycle fatigue, fatigue-creep, ratcheting, and ratcheting-creep experiments are conducted in order to study the fatigue and ratcheting responses, and their interactions with the creep response at high temperatures. A unified constitutive model developed at North Carolina State University is used to simulate these experimental responses. The model is developed based on the Chaboche viscoplastic model framework. It includes cyclic hardening/softening, strain rate dependence, strain range dependence, static and dynamic recovery modeling features. For simulation of the alloy 617 responses, new techniques of model parameter determination are developed for optimized simulations. This paper compares the experimental responses and model simulations for demonstrating the strengths and shortcomings of the model.
Date: July 1, 2013
Creator: Pritchard, P.G.; Carroll, L.J. & Hassan, T.
System: The UNT Digital Library
Constrained gamma-Z interference corrections to parity-violating electron scattering (open access)

Constrained gamma-Z interference corrections to parity-violating electron scattering

We present a comprehensive analysis of gamma-Z interference corrections to the weak charge of the proton measured in parity-violating electron scattering, including a survey of existing models and a critical analysis of their uncertainties. Constraints from parton distributions in the deep-inelastic region, together with new data on parity-violating electron scattering in the resonance region, result in significantly smaller uncertainties on the corrections compared to previous estimates. At the kinematics of the Qweak experiment, we determine the gamma-Z box correction to be Re\box_{gamma-Z}^V = (5.61 +- 0.36) x 10^{-3}. The new constraints also allow precise predictions to be made for parity-violating deep-inelastic asymmetries on the deuteron.
Date: July 1, 2013
Creator: Hall, Nathan Luke; Blunden, Peter Gwithian; Melnitchouk, Wally; Thomas, Anthony W. & Young, Ross D.
System: The UNT Digital Library
Diffusion of Scientific Knowledge in Agriculture: The Case for Africa (open access)

Diffusion of Scientific Knowledge in Agriculture: The Case for Africa

Article on the diffusion of scientific knowledge on agriculture for Africa. Using an exploratory research method, this article sets out to investigate existing knowledge diffusion models and their limitations, available best practices, and the potential to infuse translational research as a way to augment extension service programs in SSA agricultural practices.
Date: July 1, 2013
Creator: Assefa, Shimelis; Alemneh, Daniel Gelaw & Rorissa, Abebe
System: The UNT Digital Library
Effect of Chrome Coating on Resistance of Sintered Joint for ITER Central Solenoid (open access)

Effect of Chrome Coating on Resistance of Sintered Joint for ITER Central Solenoid

None
Date: July 1, 2013
Creator: Martovetsky, N. N. & Irick, D. K.
System: The UNT Digital Library
Effect of Second-Order Hydrodynamics on Floating Offshore Wind Turbines: Preprint (open access)

Effect of Second-Order Hydrodynamics on Floating Offshore Wind Turbines: Preprint

Offshore winds are generally stronger and more consistent than winds on land, making the offshore environment attractive for wind energy development. A large part of the offshore wind resource is however located in deep water, where floating turbines are the only economical way of harvesting the energy. The design of offshore floating wind turbines relies on the use of modeling tools that can simulate the entire coupled system behavior. At present, most of these tools include only first-order hydrodynamic theory. However, observations of supposed second-order hydrodynamic responses in wave-tank tests performed by the DeepCwind consortium suggest that second-order effects might be critical. In this paper, the methodology used by the oil and gas industry has been modified to apply to the analysis of floating wind turbines, and is used to assess the effect of second-order hydrodynamics on floating offshore wind turbines. The method relies on combined use of the frequency-domain tool WAMIT and the time-domain tool FAST. The proposed assessment method has been applied to two different floating wind concepts, a spar and a tension-leg-platform (TLP), both supporting the NREL 5-MW baseline wind turbine. Results showing the hydrodynamic forces and motion response for these systems are presented and analysed, and …
Date: July 1, 2013
Creator: Roald, L.; Jonkman, J.; Robertson, A, & Chokani, N.
System: The UNT Digital Library
Energetic Photon and Electron Interactions With Positive Ions (open access)

Energetic Photon and Electron Interactions With Positive Ions

The objective of this research is a deeper understanding of the complex multi-electron interactions that govern inelastic processes involving positive ions in plasma environments, such as those occurring in stellar cares and atmospheres, x-ray lasers, thermonuclear fusion reactors and materials-processing discharges. In addition to precision data on ionic structure and transition probabilities, high resolution quantitative measurements of ionization test the theoretical methods that provide critical input to computer codes used for plasma modeling and photon opacity calculations. Steadily increasing computational power and a corresponding emphasis on simulations gives heightened relevance to precise and accurate benchmark data. Photons provide a highly selective probe of the internal electronic structure of atomic and molecular systems, and a powerful means to better understand more complex electron-ion interactions.
Date: July 1, 2013
Creator: Phaneuf, Ronald A.
System: The UNT Digital Library
Evolution of the helicity and transversity Transverse-Momentum-Dependent parton distributions (open access)

Evolution of the helicity and transversity Transverse-Momentum-Dependent parton distributions

We examine the QCD evolution of the helicity and transversity parton distribution functions when including also their dependence on transverse momentum. Using an appropriate definition of these polarized transverse momentum distributions (TMDs), we describe their dependence on the factorization scale and rapidity cutoff, which is essential for phenomenological applications.
Date: July 1, 2013
Creator: Prokudin, Alexei & Bacchetta, Alessandro
System: The UNT Digital Library
The GlueX experiment: Search for gluonic excitations via photoproduction at Jefferson Lab (open access)

The GlueX experiment: Search for gluonic excitations via photoproduction at Jefferson Lab

Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by an overview of the progress at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.
Date: July 1, 2013
Creator: Eugenio, Paul
System: The UNT Digital Library
Helium Compton Form Factor Measurements at CLAS (open access)

Helium Compton Form Factor Measurements at CLAS

The distribution of the parton content of nuclei, as encoded via the generalized parton distributions (GPDs), can be accessed via the deeply virtual Compton scattering (DVCS) process contributing to the cross section for leptoproduction of real photons. Similarly to the scattering of light by a material, DVCS provides information about the dynamics and the spatial structure of hadrons. The sensitivity of this process to the lepton beam polarization allows to single-out the DVCS amplitude in terms of Compton form factors that contain GPDs information. The beam spin asymmetry of the $^4$He($\vec {\mathrm e}$,e$' \gamma ^4$He) process was measured in the experimental Hall B of the Jefferson Laboratory to extract the real and imaginary parts of the twist-2 Compton form factor of the $^4$He nucleus. The experimental results reported here demonstrate the relevance of this method for such a goal, and suggest the dominance of the Bethe-Heitler amplitude to the unpolarized process in the kinematic range explored by the experiment.
Date: July 1, 2013
Creator: Voutier, Eric J.-M.
System: The UNT Digital Library
HOM Damping Coupler Design for the 400-MHz RF Dipole Compact Crab Cavity for the LHC HiLumi Upgrade (open access)

HOM Damping Coupler Design for the 400-MHz RF Dipole Compact Crab Cavity for the LHC HiLumi Upgrade

None
Date: July 1, 2013
Creator: Li, Zenghai; Ge, Lixin; Delayen, J. R. & Silva, S. U. de
System: The UNT Digital Library
How Many Jobs are there in the Domestic Small Wind Industry? (Presentation) (open access)

How Many Jobs are there in the Domestic Small Wind Industry? (Presentation)

This poster introduces the preliminary small wind Jobs and Economic Development Impacts (JEDI) model.
Date: July 1, 2013
Creator: Tegen, S.
System: The UNT Digital Library
The INL Nuclear and Radiological Activity Center (open access)

The INL Nuclear and Radiological Activity Center

Since 1949 Idaho National Laboratory (INL) and its
Date: July 1, 2013
Creator: Chichester, D. L.; Sanders, J.; Turnage, J. A. & A., M.
System: The UNT Digital Library
Investigation of Response Amplitude Operators for Floating Offshore Wind Turbines: Preprint (open access)

Investigation of Response Amplitude Operators for Floating Offshore Wind Turbines: Preprint

This paper examines the consistency between response amplitude operators (RAOs) computed from WAMIT, a linear frequency-domain tool, to RAOs derived from time-domain computations based on white-noise wave excitation using FAST, a nonlinear aero-hydro-servo-elastic tool. The RAO comparison is first made for a rigid floating wind turbine without wind excitation. The investigation is further extended to examine how these RAOs change for a flexible and operational wind turbine. The RAOs are computed for below-rated, rated, and above-rated wind conditions. The method is applied to a floating wind system composed of the OC3-Hywind spar buoy and NREL 5-MW wind turbine. The responses are compared between FAST and WAMIT to verify the FAST model and to understand the influence of structural flexibility, aerodynamic damping, control actions, and waves on the system responses. The results show that based on the RAO computation procedure implemented, the WAMIT- and FAST-computed RAOs are similar (as expected) for a rigid turbine subjected to waves only. However, WAMIT is unable to model the excitation from a flexible turbine. Further, the presence of aerodynamic damping decreased the platform surge and pitch responses, as computed by both WAMIT and FAST when wind was included. Additionally, the influence of gyroscopic excitation increased …
Date: July 1, 2013
Creator: Ramachandran, G. K. V.; Robertson, A.; Jonkman, J. M. & Masciola, M. D.
System: The UNT Digital Library
New Automotive Air Conditioning System Simulation Tool Developed in MATLAB/Simulink (open access)

New Automotive Air Conditioning System Simulation Tool Developed in MATLAB/Simulink

Further improvements in vehicle fuel efficiency require accurate evaluation of the vehicle's transient total power requirement. When operated, the air conditioning (A/C) system is the largest auxiliary load on a vehicle; therefore, accurate evaluation of the load it places on the vehicle's engine and/or energy storage system is especially important. Vehicle simulation software, such as 'Autonomie,' has been used by OEMs to evaluate vehicles' energy performance. A transient A/C simulation tool incorporated into vehicle simulation models would also provide a tool for developing more efficient A/C systems through a thorough consideration of the transient A/C system performance. The dynamic system simulation software Matlab/Simulink was used to develop new and more efficient vehicle energy system controls. The various modeling methods used for the new simulation tool are described in detail. Comparison with measured data is provided to demonstrate the validity of the model.
Date: July 1, 2013
Creator: Kiss, T.; Chaney, L. & Meyer, J.
System: The UNT Digital Library
Novel Use of Water Soluble "Aquapour" As A Temporary Spacer During Coil Winding For The NSTX-U Centerstack (open access)

Novel Use of Water Soluble "Aquapour" As A Temporary Spacer During Coil Winding For The NSTX-U Centerstack

A major facility upgrade to the National Spherical Torus eXperiment (NSTX-U) is currently underway at Princeton Plasma Physics Laboratory (PPPL). A key component of NSTX-U is the fabrication of a new, higher field centerstack (CS). In order to simultaneously provide robust joints between the inner and outer legs of the Toroidal Field Coils (TF) and minimize radial build, the NSTX-U CS design requires that the Ohmic Heating solenoid (OH) be wound directly on the inner TF bundle. To protect the OH against thermal expansion stress during scenarios where the inner TF bundle is hot but the OH is relatively cool, the completed CS will have a 0.100 inch annular gap between the outer diameter of the TF bundle and the inner diameter of the OH solenoid. "Aquapour", a proprietary material produced by the Advanced Ceramics Manufacturing Company will be used during manufacture to produce this gap. After the TF bundle is vacuum pressure impregnated and cured, a cylindrical "clam shell" mold will be assembled around it, and a slurry of powdered Aquapour and water will be pumped into the annular space between the mold and TF bundle. Subsequent baking will turn the Aquapour solid, and a protective layer of wet …
Date: July 1, 2013
Creator: Mardenfeld, Michael
System: The UNT Digital Library
Path Integral for Stochastic Inflation: Non-Perturbative Volume Weighting, Complex Histories, Initial Conditions and the End of Inflation (open access)

Path Integral for Stochastic Inflation: Non-Perturbative Volume Weighting, Complex Histories, Initial Conditions and the End of Inflation

None
Date: July 1, 2013
Creator: Gratton, Steven & /KIPAC, Menlo Park /Cambridge U.
System: The UNT Digital Library