ADVANCED COMPOSITE WIND TURBINE BLADE DESIGN BASED ON DURABILITY AND DAMAGE TOLERANCE (open access)

ADVANCED COMPOSITE WIND TURBINE BLADE DESIGN BASED ON DURABILITY AND DAMAGE TOLERANCE

The objective of the program was to demonstrate and verify Certification-by-Analysis (CBA) capability for wind turbine blades made from advanced lightweight composite materials. The approach integrated durability and damage tolerance analysis with robust design and virtual testing capabilities to deliver superior, durable, low weight, low cost, long life, and reliable wind blade design. The GENOA durability and life prediction software suite was be used as the primary simulation tool. First, a micromechanics-based computational approach was used to assess the durability of composite laminates with ply drop features commonly used in wind turbine applications. Ply drops occur in composite joints and closures of wind turbine blades to reduce skin thicknesses along the blade span. They increase localized stress concentration, which may cause premature delamination failure in composite and reduced fatigue service life. Durability and damage tolerance (D&DT) were evaluated utilizing a multi-scale micro-macro progressive failure analysis (PFA) technique. PFA is finite element based and is capable of detecting all stages of material damage including initiation and propagation of delamination. It assesses multiple failure criteria and includes the effects of manufacturing anomalies (i.e., void, fiber waviness). Two different approaches have been used within PFA. The first approach is Virtual Crack Closure Technique …
Date: February 16, 2012
Creator: Abumeri, Galib & Abdi, Frank
Object Type: Report
System: The UNT Digital Library
Search for Dark Matter Satellites Using the FERMI-LAT (open access)

Search for Dark Matter Satellites Using the FERMI-LAT

Numerical simulations based on the {Lambda}CDM model of cosmology predict a large number of as yet unobserved Galactic dark matter satellites. We report the results of a Large Area Telescope (LAT) search for these satellites via the {gamma}-ray emission expected from the annihilation of weakly interacting massive particle (WIMP) dark matter. Some dark matter satellites are expected to have hard {gamma}-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. We sought to identify LAT sources with these characteristics, focusing on {gamma}-ray spectra consistent with WIMP annihilation through the b{bar b} channel. We found no viable dark matter satellite candidates using one year of data, and we present a framework for interpreting this result in the context of numerical simulations to constrain the velocity-averaged annihilation cross section for a conventional 100 GeV WIMP annihilating through the b{bar b} channel.
Date: August 16, 2012
Creator: Ackermann, M.; Albert, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D. et al.
Object Type: Article
System: The UNT Digital Library
First Results From the Electron Hose Instability Studies in FACET (open access)

First Results From the Electron Hose Instability Studies in FACET

None
Date: October 16, 2013
Creator: Adli, E.; Corde, S.; England, R. J.; Frederico, J.; Gessner, S. J.; Li, S. et al.
Object Type: Article
System: The UNT Digital Library
Noise Performance Evaluation of the Candidate Digitizers for the MAJORANA DEMONSTRATOR (open access)

Noise Performance Evaluation of the Candidate Digitizers for the MAJORANA DEMONSTRATOR

The noise performance evaluation of the two digitizer cards being considered for the MAJORANA DEMONSTRATOR (MJD) is presented in this document. The procurement of the data acquisition electronics for the MJD is scheduled to happen this year. At the time of writing this document, there are two candidate digitizer electronic boards. One aspect that is being considered by the collaboration is the feasibility of using the MJD for dark matter searches. The feasibility of using the MJD for this application is going to be dictated by the ability of the demonstrator to reach sub-keV energy resolution. One of the potential sources of noise in the MJD is the data acquisition system. This document will is concluded with a recommendation for the final digitizer board by comparing the noise performance of the two electronics systems. Noise parameters such as the effective number of bits, input range linearity and signal to noise ratio are experimentally determined. The two digitizer cards feature different on-board digital signal processing and these features are compared. The experimental set-up was also used to identify sources of noise. This paper describes these sources of noise in the data acquisition system, along with mitigation strategies. Issues such as grounding …
Date: March 16, 2011
Creator: Aguayo Navarrete, Estanislao
Object Type: Report
System: The UNT Digital Library
World Trade Organization (WTO): Issues in the Debate on Continued U.S. Participation (open access)

World Trade Organization (WTO): Issues in the Debate on Continued U.S. Participation

Following World War II, the United States led efforts to establish an open and nondiscriminatory trading system with the expressed goal of raising the economic well-being of all countries and bolstering world peace. These efforts culminated in the creation of the General Agreement on Tariffs and Trade (GATT) in 1948, a provisional agreement on tariffs and trade rules that governed world trade for 47 years. The World Trade Organization (WTO) succeeded the GATT in 1995 and today serves as a permanent body that administers the rules and agreements negotiated and signed by 153 participating parties, as well as a forum for dispute settlement and negotiations. The purpose of this report is to analyze some of the main issues in any debate on U.S. participation in the WTO and to address some of the criticisms leveled at the organization. Academic studies indicate that the United States benefits from broad reductions in trade barriers worldwide, but some workers and industries might not share in those gains. Decisions in the WTO are made by member governments, which determine their negotiating positions, file dispute challenges, and implement their decisions. However, some argue that smaller countries are left out of decision-making and that governments tend …
Date: June 16, 2010
Creator: Ahearn, Raymond J. & Fergusson, Ian F.
Object Type: Report
System: The UNT Digital Library
The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars (open access)

The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars

Fermi has provided the largest sample of {gamma}-ray selected blazars to date. In this work we use a complete sample of FSRQs detected during the first year of operation to determine the luminosity function (LF) and its evolution with cosmic time. The number density of FSRQs grows dramatically up to redshift {approx}0.5-2.0 and declines thereafter. The redshift of the peak in the density is luminosity dependent, with more luminous sources peaking at earlier times; thus the LF of {gamma}-ray FSRQs follows a luminosity-dependent density evolution similarly to that of radio-quiet AGN. Also using data from the Swift Burst Alert Telescope we derive the average spectral energy distribution of FSRQs in the 10 keV-100GeV band and show that there is no correlation of the peak {gamma}-ray luminosity with {gamma}-ray peak frequency. The coupling of the SED and LF allows us to predict that the contribution of FSRQs to the Fermi isotropic {gamma}-ray background is 9.3{sub -1.0}{sup +1.6}% ({+-}3% systematic uncertainty) in the 0.1-100GeV band. Finally we determine the LF of unbeamed FSRQs, finding that FSRQs have an average Lorentz factor of {gamma} = 11.7{sub -2.2}{sup +3.3}, that most are seen within 5{sup o} of the jet axis, and that they represent …
Date: April 16, 2012
Creator: Ajello, M.; Shaw, M. S.; Romani, R. W.; Dermer, C. D.; Costamante, L.; King, O. G. et al.
Object Type: Article
System: The UNT Digital Library
Advanced Compton scattering light source R&D at LLNL (open access)

Advanced Compton scattering light source R&D at LLNL

We report the design and current status of a monoenergetic laser-based Compton scattering 0.5-2.5 MeV {gamma}-ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented. At MeV photon energies relevant for nuclear processes, Compton scattering light sources are attractive because of their relative compactness and improved brightness above 100 keV, compared to typical 4th generation synchrotrons. Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable Mono-Energetic Gamma-Ray (MEGa-Ray) light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A new precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. Based on the success of the previous Thomson-Radiated Extreme X-rays (T-REX) Compton scattering source at LLNL, the source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include …
Date: February 16, 2010
Creator: Albert, F.; Anderson, S. G.; Anderson, G.; Betts, S. M.; Chu, T. S.; Gibson, D. J. et al.
Object Type: Article
System: The UNT Digital Library
Administrative Appeals in the Bureau of Land Management and the Forest Service (open access)

Administrative Appeals in the Bureau of Land Management and the Forest Service

This report describes Congressional interest in the Bureau of Land Management's (BLM) appeal process due to rumors that it affects the BLM's capacity to handle various resources. Moreover, the report defines what an administrative appeal is, and describes the process required to undertake one. The report also lists the various types of administrative appeals.
Date: September 16, 2013
Creator: Alexander, Kristina
Object Type: Report
System: The UNT Digital Library
The Lacey Act: Protecting the Environment by Restricting Trade (open access)

The Lacey Act: Protecting the Environment by Restricting Trade

Report that looks at the history and applications of the Lacey Act, which allows the U.S. to enforce the laws of other countries.
Date: July 16, 2013
Creator: Alexander, Kristina
Object Type: Report
System: The UNT Digital Library
Ready, set...go! (open access)

Ready, set...go!

The objectives of this paper are: (1) Discuss organizational readiness for changes in an ergonomics program or intervention; (2) Assessing organizational readiness; (3) Benefits and challenges of change; and (4) Case studies of ergonomic programs that were 'not ready' and 'ready'.
Date: June 16, 2010
Creator: Alexandre, Melanie
Object Type: Report
System: The UNT Digital Library
Availability Performance and Considerations for LCLS X-Ray FEL at SLAC (open access)

Availability Performance and Considerations for LCLS X-Ray FEL at SLAC

The Linac Coherent Light Source (LCLS) is an X-ray Free Electron Laser (FEL) facility located at the SLAC National Accelerator Laboratory. LCLS has been in operation since spring 2009, and it has completed its 3rd user run. LCLS is the first in its class of X-ray FEL user facilities, and presents different availability challenges compared to storage ring light sources. This paper presents recent availability performance of the FEL as well as factors to consider when defining the operational availability figure of merit for user runs. During LCLS [1] user runs, an availability of 95% has been set as a goal. In run III, LCLS photon and electron beam systems achieved availabilities of 94.8% and 96.7%, respectively. The total availability goal can be distributed among subsystems to track performance and identify areas that need attention in order to maintain and improve hardware reliability and operational availability. Careful beam time accounting is needed to understand the distribution of down time. The LCLS complex includes multiple experimental hutches for X-ray science, and each user program has different requirements of a set of parameters that the FEL can be configured to deliver. Since each user may have different criteria for what is considered …
Date: August 16, 2011
Creator: Allen, W. B.; Brachmann, A.; Colocho, W.; Stanek, M. & Warren, J.
Object Type: Article
System: The UNT Digital Library
TRACKING SURPLUS PLUTONIUM FROM WEAPONS TO DISPOSITION (open access)

TRACKING SURPLUS PLUTONIUM FROM WEAPONS TO DISPOSITION

Supporting nuclear nonproliferation and global security principles, beginning in 1994 the United States has withdrawn more than 50 metric tons (MT) of government-controlled plutonium from potential use in nuclear weapons. The Department of Energy (DOE), including the National Nuclear Security Administration, established protocols for the tracking of this "excess" and "surplus" plutonium, and for reconciling the current storage and utilization of the plutonium to show that its management is consistent with the withdrawal policies. Programs are underway to ensure the safe and secure disposition of the materials that formed a major part of the weapons stockpile during the Cold War, and growing quantities have been disposed as waste, after which they are not included in traditional nuclear material control and accountability (NMC&A) data systems. A combination of resources is used to perform the reconciliations that form the basis for annual reporting to DOE, to U.S. Department of State, and to international partners including the International Atomic Energy Agency.
Date: July 16, 2013
Creator: Allender, J.; Beams, J.; Sanders, K. & Myers, L.
Object Type: Article
System: The UNT Digital Library
2d Affine XY-Spin Model/4d Gauge Theory Duality and Deconfinement (open access)

2d Affine XY-Spin Model/4d Gauge Theory Duality and Deconfinement

We introduce a duality between two-dimensional XY-spin models with symmetry-breaking perturbations and certain four-dimensional SU(2) and SU(2) = Z{sub 2} gauge theories, compactified on a small spatial circle R{sup 1,2} x S{sup 1}, and considered at temperatures near the deconfinement transition. In a Euclidean set up, the theory is defined on R{sup 2} x T{sup 2}. Similarly, thermal gauge theories of higher rank are dual to new families of 'affine' XY-spin models with perturbations. For rank two, these are related to models used to describe the melting of a 2d crystal with a triangular lattice. The connection is made through a multi-component electric-magnetic Coulomb gas representation for both systems. Perturbations in the spin system map to topological defects in the gauge theory, such as monopole-instantons or magnetic bions, and the vortices in the spin system map to the electrically charged W-bosons in field theory (or vice versa, depending on the duality frame). The duality permits one to use the two-dimensional technology of spin systems to study the thermal deconfinement and discrete chiral transitions in four-dimensional SU(N{sub c}) gauge theories with n{sub f} {ge} 1 adjoint Weyl fermions.
Date: August 16, 2012
Creator: Anber, Mohamed M.; Poppitz, Erich; U., /Toronto; Unsal, Mithat & /SLAC /Stanford U., Phys. Dept. /San Francisco State U.
Object Type: Article
System: The UNT Digital Library
Identification and Prioritization of Analysis Cases for Marine and Hydrokinetic Energy Risk Screening (open access)

Identification and Prioritization of Analysis Cases for Marine and Hydrokinetic Energy Risk Screening

In this report we describe the development of the Environmental Risk Evaluation System (ERES), a risk-informed analytical process for estimating the environmental risks associated with the construction and operation of marine and hydrokinetic energy generation projects. The development process consists of two main phases of analysis. In the first phase, preliminary risk analyses will take the form of screening studies in which key environmental impacts and the uncertainties that create risk are identified, leading to a better-focused characterization of the relevant environmental effects. Existence of critical data gaps will suggest areas in which specific modeling and/or data collection activities should take place. In the second phase, more detailed quantitative risk analyses will be conducted, with residual uncertainties providing the basis for recommending risk mitigation and monitoring activities. We also describe the process used for selecting three cases for fiscal year 2010 risk screening analysis using the ERES. A case is defined as a specific technology deployed in a particular location involving certain environmental receptors specific to that location. The three cases selected satisfy a number of desirable criteria: 1) they correspond to real projects whose deployment is likely to take place in the foreseeable future; 2) the technology developers are …
Date: June 16, 2010
Creator: Anderson, Richard M.; Unwin, Stephen D. & Van Cleve, Frances B.
Object Type: Report
System: The UNT Digital Library
Commercial Building Partnerships Replication and Diffusion (open access)

Commercial Building Partnerships Replication and Diffusion

This study presents findings from survey and interview data investigating replication efforts of Commercial Building Partnership (CBP) partners that worked directly with the Pacific Northwest National Laboratory (PNNL). PNNL partnered directly with 12 organizations on new and retrofit construction projects, which represented approximately 28 percent of the entire U.S. Department of Energy (DOE) CBP program. Through a feedback survey mechanism, along with personal interviews, PNNL gathered quantitative and qualitative data relating to replication efforts by each organization. These data were analyzed to provide insight into two primary research areas: 1) CBP partners’ replication efforts of technologies and approaches used in the CBP project to the rest of the organization’s building portfolio (including replication verification), and, 2) the market potential for technology diffusion into the total U.S. commercial building stock, as a direct result of the CBP program. The first area of this research focused specifically on replication efforts underway or planned by each CBP program participant. Factors that impact replication include motivation, organizational structure and objectives firms have for implementation of energy efficient technologies. Comparing these factors between different CBP partners revealed patterns in motivation for constructing energy efficient buildings, along with better insight into market trends for green building …
Date: September 16, 2013
Creator: Antonopoulos, Chrissi A.; Dillon, Heather E. & Baechler, Michael C.
Object Type: Report
System: The UNT Digital Library
THGEM-Based Detectors for Sampling Elements in DHCAL: Laboratory and Beam Evaluation (open access)

THGEM-Based Detectors for Sampling Elements in DHCAL: Laboratory and Beam Evaluation

None
Date: October 16, 2013
Creator: Arazi, L.; Breskin, A.; Chechik, R.; Cortesi, M.; Pitt, M.; Rubin, A. et al.
Object Type: Article
System: The UNT Digital Library
U.S.-EU Cooperation on Ukraine and Russia (open access)

U.S.-EU Cooperation on Ukraine and Russia

This report discusses the United States, and European Union policies with Russia in response to the crisis in Ukraine.
Date: September 16, 2014
Creator: Archick, Kristin
Object Type: Report
System: The UNT Digital Library
European Security, Islamist Terrorism, and Returning Fighters (open access)

European Security, Islamist Terrorism, and Returning Fighters

This report discusses European security after the terrorist attacks in Paris. French President François Hollande attributed the attacks to the Islamic State terrorist organization (which subsequently claimed responsibility), and asserted that France's response would be "merciless."
Date: November 16, 2015
Creator: Archick, Kristin & Belkin, Paul
Object Type: Report
System: The UNT Digital Library
Terrorist Attacks in Europe and Mounting Security Concerns (open access)

Terrorist Attacks in Europe and Mounting Security Concerns

This report briefly discusses the European policy response to recent terrorist attacks.
Date: March 16, 2015
Creator: Archick, Kristin & Belkin, Paul
Object Type: Report
System: The UNT Digital Library
Border Security Metrics Between Ports of Entry (open access)

Border Security Metrics Between Ports of Entry

This report provides background and information about performance and operational metrics related to U.S. border security as well as issues for Congressional consideration.
Date: February 16, 2016
Creator: Argueta, Carla N.
Object Type: Report
System: The UNT Digital Library
Guinea: In Brief (open access)

Guinea: In Brief

This report provides background information on politics and economy of Guinea. The report discusses human rights and governance in Guinea, as well as the role of military, drug trafficking and mining sector.
Date: October 16, 2014
Creator: Arieff, Alexis
Object Type: Report
System: The UNT Digital Library
Political Transition in Tunisia (open access)

Political Transition in Tunisia

This report discusses Tunisia's "Jasmine Revolution," the common term for President Zine El Abidine Ben Ali's flight from the country following weeks of mounting anti-government protests. This report discusses how the Jasmine Revolution appears to have added momentum to anti-government sentiment in Egypt, Libya, Yemen, and other countries. This report discusses Tunisia's pro-democracy movement; concerns over potential instability in a previously secure, pro-Western area; and U.S.-Tunisian relations.
Date: December 16, 2011
Creator: Arieff, Alexis
Object Type: Report
System: The UNT Digital Library
Senegal: Background and U.S. Relations (open access)

Senegal: Background and U.S. Relations

This report covers the background, recent politics, government, and economy of Senegal. It also looks at security and human rights issues and Senegal's ties with France and the Middle East. It ends with a look at U.S. - Senegal relations.
Date: August 16, 2010
Creator: Arieff, Alexis
Object Type: Report
System: The UNT Digital Library
Crisis In Mali (open access)

Crisis In Mali

This report discusses the West African country of Mali that faces multiple overlapping crises. The country’s political leadership has been uncertain and disputed since a military coup on March 22, 2012, overthrew a democratically elected government in the capital, Bamako.
Date: August 16, 2012
Creator: Arieff, Alexis & Johnson, Kelly
Object Type: Report
System: The UNT Digital Library