Atom chip microscopy: A novel probe for strongly correlated materials (open access)

Atom chip microscopy: A novel probe for strongly correlated materials

Improved measurements of strongly correlated systems will enable the predicative design of the next generation of supermaterials. In this program, we are harnessing recent advances in the quantum manipulation of ultracold atomic gases to expand our ability to probe these technologically important materials in heretofore unexplored regions of temperature, resolution, and sensitivity parameter space. We are working to demonstrate the use of atom chips to enable single-shot, large area detection of magnetic flux at the 10^-7 flux quantum level and below. By harnessing the extreme sensitivity of atomic clocks and Bose-Einstein condensates (BECs) to external perturbations, the cryogenic atom chip technology developed here will provide a magnetic flux detection capability that surpasses other techniques---such as scanning SQUIDs---by a factor of 10--1000. We are testing the utility of this technique by using rubidium BECs to image the magnetic fields emanating from charge transport and magnetic domain percolation in strongly correlated materials as they undergo temperature-tuned metal--to--insulator phase transitions. Cryogenic atom chip microscopy introduces three very important features to the toolbox of high-resolution, strongly correlated material microscopy: simultaneous detection of magnetic and electric fields (down to the sub-single electron charge level); no invasive large magnetic fields or gradients; simultaneous micro- and macroscopic …
Date: November 3, 2011
Creator: Lev, Benjamin L
Object Type: Report
System: The UNT Digital Library
Development of Facilities Master Plan and Laboratory Renovation Project (open access)

Development of Facilities Master Plan and Laboratory Renovation Project

Funding from this grant has allowed Morehouse School of Medicine to complete its first professionally developed, comprehensive campus master plan that is in alignment with the recently completed strategic plan. In addition to master planning activities, funds were used for programming and designing research renovations, and also to supplement other research facility upgrades by providing lighting and equipment. The activities funded by this grant will provide the catalyst for substantial improvement in the School’s overall facilities for biomedical education and research, and will also provide much of the information needed to conduct a successful campaign to raise funds for proposed buildings and renovations.
Date: October 3, 2011
Creator: Fox, Andrea D.
Object Type: Report
System: The UNT Digital Library
Iterative Algorithms for Ptychographic Phase Retrieval (open access)

Iterative Algorithms for Ptychographic Phase Retrieval

Ptychography promises diffraction limited resolution without the need for high resolution lenses. To achieve high resolution one has to solve the phase problem for many partially overlapping frames. Here we review some of the existing methods for solving ptychographic phase retrieval problem from a numerical analysis point of view, and propose alternative methods based on numerical optimization.
Date: May 3, 2011
Creator: Yang, Chao; Qian, Jianliang; Schirotzek, Andre; Maia, Filipe & Marchesini, Stefano
Object Type: Article
System: The UNT Digital Library
Higher-order mode analysis at the BNL Energy Recovery Linac (open access)

Higher-order mode analysis at the BNL Energy Recovery Linac

Understanding the prevalence and structure of higher-order modes (HOMs) in accelerator cavities is critical because their excitation can result in problematic single bunch and multi-bunch effects. Particularly hazardous are dipole modes, which are more easily excited due to their linear field nature near the beam center. During a recent superconducting test on the energy recovery linac (ERL) cavity at Brookhaven National Laboratory (BNL), 8 of the highest-Q HOMs were measured for the first time. In conjunction with analysis of CST Microwave Studio simulation results for the ERL model, one of these modes was further studied in the copper prototype ERL cavity. A method of identifying HOMs utilizing existing holes drilled in copper cavity cells was developed and used to conclude that the observed high-Q mode was a quadrupole.
Date: August 3, 2011
Creator: Johnson, E. C.; Ben-Zvi, Ilan; Hahn, H.; Hammons, L. & Xu, W.
Object Type: Report
System: The UNT Digital Library
DEVELOPMENT OF A LAMINATED DISK FOR THE SPIN TEK ROTARY MICROFILTER (open access)

DEVELOPMENT OF A LAMINATED DISK FOR THE SPIN TEK ROTARY MICROFILTER

Funded by the Department of Energy Office of Environmental Management, EM-31, the Savannah River National Laboratory (SRNL) partnered with SpinTek Filtration{trademark} to develop a filter disk that would withstand a reverse pressure or flow during operation of the rotary microfilter. The ability to withstand a reverse pressure and flow eliminates a potential accident scenario that could have resulted in damage to the filter membranes. While the original welded filter disks have been shown to withstand and reverse pressure/flow in the static condition, the filter disk design discussed in this report will allow a reverse pressure/flow while the disks are rotating. In addition, the laminated disk increases the flexibility during filter startup and cleaning operations. The new filter disk developed by SRNL and SpinTek is manufactured with a more open structure significantly reducing internal flow restrictions in the disk. The prototype was tested at the University of Maryland and demonstrated to withstand the reverse pressure due to the centrifugal action of the rotary filter. The tested water flux of the disk was demonstrated to be 1.34 gpm in a single disk test. By comparison, the water flux of the current disk was 0.49 gpm per disk during a 25 disk test. …
Date: June 3, 2011
Creator: Herman, D.
Object Type: Report
System: The UNT Digital Library
Measures of trajectory ensemble disparity in nonequilibrium statistical dynamics (open access)

Measures of trajectory ensemble disparity in nonequilibrium statistical dynamics

Many interesting divergence measures between conjugate ensembles of nonequilibrium trajectories can be experimentally determined from the work distribution of the process. Herein, we review the statistical and physical significance of several of these measures, in particular the relative entropy (dissipation), Jeffreys divergence (hysteresis), Jensen-Shannon divergence (time-asymmetry), Chernoff divergence (work cumulant generating function), and Renyi divergence.
Date: June 3, 2011
Creator: Crooks, Gavin & Sivak, David
Object Type: Article
System: The UNT Digital Library
BENCH SCALE SALTSTONE PROCESS DEVELOPMENT MIXING STUDY (open access)

BENCH SCALE SALTSTONE PROCESS DEVELOPMENT MIXING STUDY

The Savannah River National Laboratory (SRNL) was requested to develop a bench scale test facility, using a mixer, transfer pump, and transfer line to determine the impact of conveying the grout through the transfer lines to the vault on grout properties. Bench scale testing focused on the effect the transfer line has on the rheological property of the grout as it was processed through the transfer line. Rheological and other physical properties of grout samples were obtained prior to and after pumping through a transfer line. The Bench Scale Mixing Rig (BSMR) consisted of two mixing tanks, grout feed tank, transfer pump and transfer hose. The mixing tanks were used to batch the grout which was then transferred into the grout feed tank. The contents of the feed tank were then pumped through the transfer line (hose) using a progressive cavity pump. The grout flow rate and pump discharge pressure were monitored. Four sampling stations were located along the length of the transfer line at the 5, 105 and 205 feet past the transfer pump and at 305 feet, the discharge of the hose. Scaling between the full scale piping at Saltstone to bench scale testing at SRNL was performed …
Date: August 3, 2011
Creator: Cozzi, A. & Hansen, E.
Object Type: Report
System: The UNT Digital Library
Fast Ion Effects During Test Blanket Module Simulation Experiments in DIII-D (open access)

Fast Ion Effects During Test Blanket Module Simulation Experiments in DIII-D

Fast beam-ion losses were studied in DIII-D in the presence of a scaled mockup of two Test Blanket Modules (TBM) for ITER. Heating of the protective tiles on the front of the TBM surface was found when neutral beams were injected and the TBM fields were engaged. The fast-ion core confinement was not significantly affected. Different orbit-following codes predict the formation of a hot spot on the TBM surface arising from beam-ions deposited near the edge of the plasma. The codes are in good agreement with each other on the total power deposited at the hot spot predicting an increase in power with decreasing separation between the plasma edge and the TBM surface. A thermal analysis of the heat flow through the tiles shows that the simulated power can account for the measured tile temperature rise. The thermal analysis, however, is very sensitive to the details of the localization of the hot spot which is predicted to be different among the various codes.
Date: June 3, 2011
Creator: Kramer, G. J.; Ellis, R.; Gorelenkova, M.; Heidbrink, W. W.; Kurki-Suonio, T.; Nazikian, R. et al.
Object Type: Report
System: The UNT Digital Library
Particle Suspension Mechanisms - Supplemental Material (open access)

Particle Suspension Mechanisms - Supplemental Material

This supplemental material provides a brief introduction to particle suspension mechanisms that cause exfoliated skin cells to become and remain airborne. The material presented here provides additional context to the primary manuscript and serves as background for designing possible future studies to assess the impact of skin cells as a source of infectious aerosols. This introduction is not intended to be comprehensive and interested readers are encouraged to consult the references cited.
Date: March 3, 2011
Creator: Dillon, M B
Object Type: Article
System: The UNT Digital Library
UCSD Support for Fusion Simulation Project Planning Activity (open access)

UCSD Support for Fusion Simulation Project Planning Activity

This document is a close-out report on work performed by UCSD researchers in support of the Fusion Simulation Project Planning Activity.
Date: November 3, 2011
Creator: Holland, C.; Tynan, G. R. & Diamond, P. H.
Object Type: Text
System: The UNT Digital Library
Water management practices used by Fayetteville shale gas producers. (open access)

Water management practices used by Fayetteville shale gas producers.

Water issues continue to play an important role in producing natural gas from shale formations. This report examines water issues relating to shale gas production in the Fayetteville Shale. In particular, the report focuses on how gas producers obtain water supplies used for drilling and hydraulically fracturing wells, how that water is transported to the well sites and stored, and how the wastewater from the wells (flowback and produced water) is managed. Last year, Argonne National Laboratory made a similar evaluation of water issues in the Marcellus Shale (Veil 2010). Gas production in the Marcellus Shale involves at least three states, many oil and gas operators, and multiple wastewater management options. Consequently, Veil (2010) provided extensive information on water. This current study is less complicated for several reasons: (1) gas production in the Fayetteville Shale is somewhat more mature and stable than production in the Marcellus Shale; (2) the Fayetteville Shale underlies a single state (Arkansas); (3) there are only a few gas producers that operate the large majority of the wells in the Fayetteville Shale; (4) much of the water management information relating to the Marcellus Shale also applies to the Fayetteville Shale, therefore, it can be referenced from …
Date: June 3, 2011
Creator: Veil, J. A. (Environmental Science Division)
Object Type: Report
System: The UNT Digital Library
General-purpose event generators for LHC physics (open access)

General-purpose event generators for LHC physics

We review the physics basis, main features and use of general-purpose Monte Carlo event generators for the simulation of proton-proton collisions at the Large Hadron Collider. Topics included are: the generation of hard-scattering matrix elements for processes of interest, at both leading and next-to-leading QCD perturbative order; their matching to approximate treatments of higher orders based on the showering approximation; the parton and dipole shower formulations; parton distribution functions for event generators; non-perturbative aspects such as soft QCD collisions, the underlying event and diffractive processes; the string and cluster models for hadron formation; the treatment of hadron and tau decays; the inclusion of QED radiation and beyond-Standard-Model processes. We describe the principal features of the Ariadne, Herwig++, Pythia 8 and Sherpa generators, together with the Rivet and Professor validation and tuning tools, and discuss the physics philosophy behind the proper use of these generators and tools. This review is aimed at phenomenologists wishing to understand better how parton-level predictions are translated into hadron-level events as well as experimentalists wanting a deeper insight into the tools available for signal and background simulation at the LHC.
Date: March 3, 2011
Creator: Buckley, Andy; Butterworth, Jonathan; Gieseke, Stefan; Grellscheid, David; Hoche, Stefan; Hoeth, Hendrik et al.
Object Type: Article
System: The UNT Digital Library
Modification Of The Electron Energy Distribution Function During Lithium Experiments On The National Spherical Torus Experiment (open access)

Modification Of The Electron Energy Distribution Function During Lithium Experiments On The National Spherical Torus Experiment

The National Spherical Torus Experiment (NSTX) has recently studied the use of a liquid lithium divertor (LLD). Divertor Langmuir probes have also been installed for making measurements of the local plasma conditions. A non-local probe interpretation method is used to supplement the classical probe interpretation and obtain measurements of the electron energy distribution function (EEDF) which show the occurrence of a hot-electron component. Analysis is made of two discharges within a sequence that exhibited changes in plasma fueling efficiency. It is found that the local electron temperature increases and that this increase is most strongly correlated with the energy contained within the hot-electron population. Preliminary interpretative modeling indicates that kinetic effects are likely in the NSTX.
Date: June 3, 2011
Creator: Jaworski, M. A.; Gray, T. K.; Kaita, R.; Kallman, J.; Kugel, H.; LeBlanc, B. et al.
Object Type: Report
System: The UNT Digital Library
ROTARY FILTER FINES TESTING FOR SMALL COLUMN ION EXCHANGE (open access)

ROTARY FILTER FINES TESTING FOR SMALL COLUMN ION EXCHANGE

SRNL was requested to quantify the amount of 'fines passage' through the 0.5 micron membranes currently used for the rotary microfilter (RMF). Testing was also completed to determine if there is any additional benefit to utilizing a 0.1 micron filter to reduce the amount of fines that could pass through the filter. Quantifying of the amount of fines that passed through the two sets of membranes that were tested was accomplished by analyzing the filtrate by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) for titanium. Even with preparations to isolate the titanium, all samples returned results of less than the instrument's detection limit of 0.184 mg/L. Test results show that the 0.5 micron filters produced a significantly higher flux while showing a negligible difference in filtrate clarity measured by turbidity. The first targeted deployment of the RMF is with the Small Column Ion Exchange (SCIX) at the Savannah River Site (SRS). SCIX uses crystalline silicotitanate (CST) to sorb cesium to decontaminate a clarified salt solution. The passage of fine particles through the filter membranes in sufficient quantities has the potential to impact the downstream facilities. To determine the amount of fines passage, a contract was established with SpinTek Filtration to …
Date: August 3, 2011
Creator: Herman, D.
Object Type: Report
System: The UNT Digital Library
Lensless x-ray imaging in reflection geometry (open access)

Lensless x-ray imaging in reflection geometry

Lensless X-ray imaging techniques such as coherent diffraction imaging and ptychography, and Fourier transform holography can provide time-resolved, diffraction-limited images. Nearly all examples of these techniques have focused on transmission geometry, restricting the samples and reciprocal spaces that can be investigated. We report a lensless X-ray technique developed for imaging in Bragg and small-angle scattering geometries, which may also find application in transmission geometries. We demonstrate this by imaging a nanofabricated pseudorandom binary structure in small-angle reflection geometry. The technique can be used with extended objects, places no restriction on sample size, and requires no additional sample masking. The realization of X-ray lensless imaging in reflection geometry opens up the possibility of single-shot imaging of surfaces in thin films, buried interfaces in magnetic multilayers, organic photovoltaic and field-effect transistor devices, or Bragg planes in a single crystal.
Date: February 3, 2011
Creator: Roy, S.; Parks, D. H.; Seu, K. A.; Turner, J. J.; Chao, W.; Anderson, E. H. et al.
Object Type: Article
System: The UNT Digital Library
Seaborne Delivery Interdiction of Weapons of Mass Destruction (WMD) (open access)

Seaborne Delivery Interdiction of Weapons of Mass Destruction (WMD)

Over the next 10-20 years, the probability of a terrorist attack using a weapon of mass destruction (WMD) on the United States is projected to increase. At some point over the next few decades, it may be inevitable that a terrorist group will have access to a WMD. The economic and social impact of an attack using a WMD anywhere in the world would be catastrophic. For weapons developed overseas, the routes of entry are air and sea with the maritime vector as the most porous. Providing a system to track, perform a risk assessment and inspect all inbound marine traffic before it reaches US coastal cities thereby mitigating the threat has long been a goal for our government. The challenge is to do so effectively without crippling the US economy. The Portunus Project addresses only the maritime threat and builds on a robust maritime domain awareness capability. It is a process to develop the technologies, policies and practices that will enable the US to establish a waypoint for the inspection of international marine traffic, screen 100% of containerized and bulk cargo prior to entry into the US if deemed necessary, provide a palatable economic model for transshipping, grow the …
Date: March 3, 2011
Creator: Glauser, H
Object Type: Report
System: The UNT Digital Library
RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics (open access)

RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics

The LHC RF station-beam interaction strongly influences the longitudinal beam dynamics, both single bunch and collective effects. Non-linearities and noise generated within the Radio Frequency (RF) accelerating system interact with the beam and contribute to beam motion and longitudinal emittance blowup. Thus, the noise power spectrum of the RF accelerating voltage strongly affects the longitudinal beam distribution. Furthermore, the coupled-bunch instabilities are also directly affected by the RF components and the configuration of the Low Level RF (LLRF) feedback loops. In this work we present a formalism relating the longitudinal beam dynamics with the RF system configurations, an estimation of collective effects stability margins, and an evaluation of longitudinal sensitivity to various LLRF parameters and configurations.
Date: March 3, 2011
Creator: Mastorides, T.; Rivetta, C.; Fox, J. D.; Winkle, D. Van & Baudrenghien, P.
Object Type: Article
System: The UNT Digital Library
Technical Advice and Support for the Joint Integrated Non-Intrusive Inspection (JINII) Program Task 2.2 Transmission Digital Radiography (DR) (open access)

Technical Advice and Support for the Joint Integrated Non-Intrusive Inspection (JINII) Program Task 2.2 Transmission Digital Radiography (DR)

The Cargo Advanced Automated Radiography System (CAARS) program aims to utilize advanced radiographic systems to detect radiological and nuclear threats. Validation of initial design and testing concepts is a precondition for prototype system development and large-scale deployment. As expected, Depleted Uranium (DU) is a valid surrogate for Special Nuclear Materials (SNM) in CAARS Advanced Technology Demonstration (ATD) performance field-tests of transmission radiography systems. Dual-energy transmission measurements of DU are nearly identical to SNM, and are distinct from lower Z materials, provided the samples are matched to equal areal density. Results from an alternative method, using samples of equal thickness, showed sample discrimination by material density, rather than by atomic number (Z). The transmission measurements of DU and SNM were made with equipment that is nearly identical to current field systems. X-ray source beams at endpoint energies of 5.4 MeV and 9.6 MeV were used to measure transmission through the selected sample materials. The ratio of the x-ray linear attenuation coefficient times length ({micro}L) at 5.4 MeV, to {micro}L at 9.6 MeV is a metric for atomic number based discrimination of materials. The measured ratios were compared with computed values based on LLNL photon cross section data and LLNL developed models …
Date: March 3, 2011
Creator: Martz, H; Chinn, D & Pincus, C
Object Type: Report
System: The UNT Digital Library
A measurement of the 2 neutrino double beta decay rate of Te-130 in the CUORICINO experiment (open access)

A measurement of the 2 neutrino double beta decay rate of Te-130 in the CUORICINO experiment

CUORICINO was a cryogenic bolometer experiment designed to search for neutrinoless double beta decay and other rare processes, including double beta decay with two neutrinos (2{nu}{beta}{beta}). The experiment was located at Laboratori Nazionali del Gran Sasso and ran for a period of about 5 years, from 2003 to 2008. The detector consisted of an array of 62 TeO{sub 2} crystals arranged in a tower and operated at a temperature of #24;10 mK. Events depositing energy in the detectors, such as radioactive decays or impinging particles, produced thermal pulses in the crystals which were read out using sensitive thermistors. The experiment included 4 enriched crystals, 2 enriched with {sup 130}Te and 2 with {sup 128}Te, in order to aid in the measurement of the 2{nu}{beta}{beta} rate. The enriched crystals contained a total of #24;350 g {sup 130}Te. The 128-enriched (130-depleted) crystals were used as background monitors, so that the shared backgrounds could be subtracted from the energy spectrum of the 130- enriched crystals. Residual backgrounds in the subtracted spectrum were fit using spectra generated by Monte-Carlo simulations of natural radioactive contaminants located in and on the crystals. The 2{nu}{beta}{beta} half-life was measured to be T{sup 2{nu}}{sub 1/2} = [9.81{+-} #6;0.96(stat){+-} 0.49(syst)]#2;x10{sup …
Date: November 3, 2011
Creator: Kogler, Laura
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Experience report with the Alignment Diagnostic System (open access)

Experience report with the Alignment Diagnostic System

Since 2009 an Alignment Diagnostic System (ADS) has been operating at the undulator of the new Linac Coherent Light Source at SLAC National Accelerator Laboratory. The undulator spans a distance of 132 meters and is structured into 33 segments. Each segment is equipped with four hydrostatic leveling sensors and four wire position monitors. This report describes the set up and reflects the experience gained with the ADS.
Date: March 3, 2011
Creator: Gassner, Georg
Object Type: Article
System: The UNT Digital Library
IMPACTS OF SMALL COLUMN ION EXCHANGE STREAMS ON DWPF GLASS FORMULATION: KT05- AND KT06-SERIES GLASS COMPOSITIONS (open access)

IMPACTS OF SMALL COLUMN ION EXCHANGE STREAMS ON DWPF GLASS FORMULATION: KT05- AND KT06-SERIES GLASS COMPOSITIONS

This report is the second in a series of studies of the impacts of the addition of Crystalline Silicotitanate (CST) and Monosodium Titanate (MST) from the Small Column Ion Exchange (SCIX) process on the Defense Waste Processing Facility (DWPF) glass waste form and the applicability of the DWPF process control models. The KT05-series glasses were selected, fabricated, and characterized to further study glass compositions where iron titanate crystals had been previously found to form. The intent was to better understand the mechanisms and compositions that favored the formation of crystals containing titanium. Formation of these crystalline phases was confirmed. Increased Na{sub 2}O concentrations had little if any impact on reducing the propensity for the formation of the iron titanate crystalline phases. Other physical properties of these glasses were not measured since the intent was to focus on crystallization. Additional studies are suggested to investigate the potential impacts of Al{sub 2}O{sub 3} and K{sub 2}O on crystallization in glasses with high TiO{sub 2} concentrations. The KT06-series glasses were selected, fabricated, and characterized to further study glass compositions that, while broader than the current projections for DWPF feeds with SCIX material, are potential candidates for future processing (i.e., the compositions are acceptable …
Date: January 3, 2011
Creator: Fox, K. & Edwards, T.
Object Type: Report
System: The UNT Digital Library
Cncc Craig Campus Geothermal Project: 82-Well Closed Loop GHP Well Field to Provide Geothermal Energy as a Common Utilitiy for a New Community College Campus (open access)

Cncc Craig Campus Geothermal Project: 82-Well Closed Loop GHP Well Field to Provide Geothermal Energy as a Common Utilitiy for a New Community College Campus

Colorado Northwestern Community College (CNCC) is working collaboratively with recipient vendor Chevron Energy Solutions, an energy services company (ESCO), to develop an innovative GHP project at the new CNCC Campus constructed in 2010/2011 in Craig, Colorado. The purpose of the CNCC Craig Campus Geothermal Program scope was to utilize an energy performance contracting approach to develop a geothermal system with a shared closed-loop field providing geothermal energy to each building's GHP mechanical system. Additional benefits to the project include promoting good jobs and clean energy while reducing operating costs for the college. The project has demonstrated that GHP technology is viable for new construction using the energy performance contracting model. The project also enabled the project team to evaluate several options to give the College a best value proposition for not only the initial design and construction costs but build high performance facilities that will save the College for many years to come. The design involved comparing the economic feasibility of GHP by comparing its cost to that of traditional HVAC systems via energy model, financial life cycle cost analysis of energy savings and capital cost, and finally by evaluating the compatibility of the mechanical design for GHP compared to …
Date: January 3, 2011
Creator: Solutions, Chevron Energy; Rush, Matt & Shulda, Scott
Object Type: Report
System: The UNT Digital Library
Light Duty Efficient, Clean Combustion (open access)

Light Duty Efficient, Clean Combustion

Cummins has successfully completed the Light Duty Efficient Clean Combustion (LDECC) cooperative program with DoE. This program was established in 2007 in support of the Department of Energy’s Vehicles Technologies Advanced Combustion and Emissions Control initiative to remove critical barriers to the commercialization of advanced, high efficiency, emissions compliant internal combustion (IC) engines for light duty vehicles. Work in this area expanded the fundamental knowledge of engine combustion to new regimes and advanced the knowledge of fuel requirements for these diesel engines to realize their full potential. All of the following objectives were met with fuel efficiency improvement targets exceeded: 1. Improve light duty vehicle (5000 lb. test weight) fuel efficiency by 10.5% over today’s state-ofthe- art diesel engine on the FTP city drive cycle 2. Develop & design an advanced combustion system plus aftertreatment system that synergistically meets Tier 2 Bin 5 NOx and PM emissions standards while demonstrating the efficiency improvements. 3. Maintain power density comparable to that of current conventional engines for the applicable vehicle class. 4. Evaluate different fuel components and ensure combustion system compatibility with commercially available biofuels. Key accomplishments include:  A 25% improvement in fuel efficiency was achieved with the advanced LDECC engine …
Date: June 3, 2011
Creator: Stanton, Donald W.
Object Type: Report
System: The UNT Digital Library
I/O Performance of Virtualized Cloud Environments (open access)

I/O Performance of Virtualized Cloud Environments

The scientific community is exploring the suitability of cloud infrastructure to handle High Performance Computing (HPC) applications. The goal of Magellan, a project funded through DOE ASCR, is to investigate the potential role of cloud computing to address the computing needs of the Department of Energy?s Office of Science, especially for mid-range computing and data-intensive applications which are not served through existing DOE centers today. Prior work has shown that applications with significant communication orI/O tend to perform poorly in virtualized cloud environments. However, there is a limited understanding of the I/O characteristics in virtualized cloud environments. This paper will present our results in benchmarking the I/O performance over different cloud and HPC platforms to identify the major bottlenecks in existing infrastructure. We compare the I/O performance using IOR benchmark on two cloud platforms - Amazon and Magellan. We analyze the performance of different storage options available, different instance types in multiple availability zones. Finally, we perform large-scale tests in order to analyze the variability in the I/O patterns over time and region. Our results highlight the overhead and variability in I/O performance on both public and private cloud solutions. Our results will help applications decide between the different storage …
Date: November 3, 2011
Creator: Ghoshal, Devarshi; Canon, Shane & Ramakrishnan, Lavanya
Object Type: Article
System: The UNT Digital Library