Developing an Instrumentation Package for in-Water Testing of Marine Hydrokinetic Energy Devices: Preprint (open access)

Developing an Instrumentation Package for in-Water Testing of Marine Hydrokinetic Energy Devices: Preprint

The ocean-energy industry is still in its infancy and device developers have provided their own equipment and procedures for testing. Currently, no testing standards exist for ocean energy devices in the United States. Furthermore, as prototype devices move from the test tank to in-water testing, the logistical challenges and costs grow exponentially. Development of a common instrumentation package that can be moved from device to device is one means of reducing testing costs and providing normalized data to the industry as a whole. As a first step, the U.S. National Renewable Energy Laboratory (NREL) has initiated an effort to develop an instrumentation package to provide a tool to allow common measurements across various ocean energy devices. The effort is summarized in this paper. First, we present the current status of ocean energy devices. We then review the experiences of the wind industry in its development of the instrumentation package and discuss how they can be applied in the ocean environment. Next, the challenges that will be addressed in the development of the ocean instrumentation package are discussed. For example, the instrument package must be highly adaptable to fit a large array of devices but still conduct common measurements. Finally, some …
Date: August 1, 2010
Creator: Nelson, E.
Object Type: Article
System: The UNT Digital Library
Opportunities for Open Automated Demand Response in Wastewater Treatment Facilities in California - Phase II Report. San Luis Rey Wastewater Treatment Plant Case Study (open access)

Opportunities for Open Automated Demand Response in Wastewater Treatment Facilities in California - Phase II Report. San Luis Rey Wastewater Treatment Plant Case Study

This case study enhances the understanding of open automated demand response opportunities in municipal wastewater treatment facilities. The report summarizes the findings of a 100 day submetering project at the San Luis Rey Wastewater Treatment Plant, a municipal wastewater treatment facility in Oceanside, California. The report reveals that key energy-intensive equipment such as pumps and centrifuges can be targeted for large load reductions. Demand response tests on the effluent pumps resulted a 300 kW load reduction and tests on centrifuges resulted in a 40 kW load reduction. Although tests on the facility?s blowers resulted in peak period load reductions of 78 kW sharp, short-lived increases in the turbidity of the wastewater effluent were experienced within 24 hours of the test. The results of these tests, which were conducted on blowers without variable speed drive capability, would not be acceptable and warrant further study. This study finds that wastewater treatment facilities have significant open automated demand response potential. However, limiting factors to implementing demand response are the reaction of effluent turbidity to reduced aeration load, along with the cogeneration capabilities of municipal facilities, including existing power purchase agreements and utility receptiveness to purchasing electricity from cogeneration facilities.
Date: August 20, 2010
Creator: Thompson, Lisa; Lekov, Alex; McKane, Aimee & Piette, Mary Ann
Object Type: Report
System: The UNT Digital Library
Walmart Experimental Store Performance Stories: Preprint (open access)

Walmart Experimental Store Performance Stories: Preprint

Walmart opened two experimental stores--one in Colorado and one in Texas--in 2005 to serve as test beds for several advanced building systems. Each embodied more than 50 experiments covering materials, water systems, energy systems, and renewable energy production. Walmart worked for three years with the National Renewable Energy Laboratory for the Colorado Store and Oak Ridge National Laboratory for the Texas store to monitor, analyze, and report on their performance. HVAC experiments included waste oil boilers, a microturbine/absorption chiller combined heat and power system, evaporative cooling, and a transpired solar collector. The refrigeration systems integrated a medium-temperature secondary loop, evaporatively cooled condenser, doors on medium-temperature cases, and light-emitting diodes on cases. Experiments in the lighting systems included a redesigned roof for clerestory daylighting and T-5 fluorescent lamps. Three photovoltaic systems for a total of 135 kW and a 50-kW wind turbine are also included. The energy system performance was compared to the measured performance of a prototypical Walmart store and to other benchmarks.
Date: August 1, 2010
Creator: Deru, M.; Kozubal, E. & Norton, P.
Object Type: Article
System: The UNT Digital Library
2009 Wind Technologies Market Report (open access)

2009 Wind Technologies Market Report

The U.S. wind power industry experienced yet another record year in 2009, once again surpassing even optimistic growth projections from years past. At the same time, 2009 was a year of upheaval, with the global financial crisis impacting the wind power industry and with federal policy changes enacted to push the industry toward continued aggressive expansion. The year 2010, meanwhile, is anticipated to be one of some retrenchment, with expectations for fewer wind power capacity additions than seen in 2009. The rapid pace of development and change within the industry has made it difficult to keep up with trends in the marketplace, yet the need for timely, objective information on the industry and its progress has never been greater. This report - the fourth in an ongoing annual series - attempts to meet this need by providing a detailed overview of developments and trends in the United States wind power market, with a particular focus on 2009.
Date: August 1, 2010
Creator: Wiser, R. & Bolinger, M.
Object Type: Report
System: The UNT Digital Library
Practical Integration Approach and Whole Building Energy Simulation of Three Energy Efficient Building Technologies: Preprint (open access)

Practical Integration Approach and Whole Building Energy Simulation of Three Energy Efficient Building Technologies: Preprint

Three technologies that have potential to save energy and improve sustainability of buildings are dedicated outdoor air systems, radiant heating and cooling systems and tighter building envelopes. To investigate the energy savings potential of these three technologies, whole building energy simulations were performed for a barracks facility and an administration facility in 15 U.S. climate zones and 16 international locations.
Date: August 1, 2010
Creator: Miller, J. P.; Zhivov, A.; Heron, D.; Deru, M. & Benne, K.
Object Type: Article
System: The UNT Digital Library
Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS) (open access)

Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities …
Date: August 31, 2010
Creator: Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim et al.
Object Type: Report
System: The UNT Digital Library
Building Energy Simulation Test for Existing Homes (BESTEST-EX); Phase 1 Test Procedure: Building Thermal Fabric Cases (open access)

Building Energy Simulation Test for Existing Homes (BESTEST-EX); Phase 1 Test Procedure: Building Thermal Fabric Cases

The U.S. Department of Energy tasked NREL to develop a process for testing the reliability of models that predict retrofit energy savings, including their associated calibration methods. DOE asked NREL to conduct the work in phases so that a test procedure would be ready should DOE need it to meet legislative requirements related to residential retrofits in FY 2010. This report documents the initial 'Phase 1' test procedure.
Date: August 1, 2010
Creator: Judkoff, R.; Polly, B.; Bianchi, M. & Neymark, J.
Object Type: Report
System: The UNT Digital Library
Optimization of the LCLS Single Pulse Shutter (open access)

Optimization of the LCLS Single Pulse Shutter

A mechanical shutter which operates on demand is used to isolate a single pulse from a 120 Hz X-ray source. This is accomplished with a mechanical shutter which is triggered on demand with frequencies ranging from 0 to 10 Hz. The single pulse shutter is an iron blade that oscillates on a pivot in response to a force generated by a pair of pulsed electromagnets (current driven teeter-totter). To isolate an individual pulse from the X-ray beam, the motion of the mechanical shutter should be synchronized in such a way that it allows a single pulse to pass through the aperture and blocks the other incoming pulses. Two consecutive pulses are only {approx} 8 ms apart and the shutter is required to complete one full cycle such that no two pulses pass through the opening. Also the opening of the shutter blade needs to be at least 4 mm so that a 1 mm diameter rms Gaussian beam can pass through without modulation. However, the 4 mm opening is difficult to obtain due to blade rebound and oscillation of the blade after colliding with the electromagnet. The purpose of this project is to minimize and/or totally eliminate the rebound of …
Date: August 25, 2010
Creator: Adera, Solomon & /Georgia Tech., Atlanta /SLAC
Object Type: Report
System: The UNT Digital Library
Fuel Efficient Diesel Particulate Filter (DPF) Modeling and Development (open access)

Fuel Efficient Diesel Particulate Filter (DPF) Modeling and Development

The project described in this report seeks to promote effective diesel particulate filter technology with minimum fuel penalty by enhancing fundamental understanding of filtration mechanisms through targeted experiments and computer simulations. The overall backpressure of a filtration system depends upon complex interactions of particulate matter and ash with the microscopic pores in filter media. Better characterization of these phenomena is essential for exhaust system optimization. The acicular mullite (ACM) diesel particulate filter substrate is under continuing development by Dow Automotive. ACM is made up of long mullite crystals which intersect to form filter wall framework and protrude from the wall surface into the DPF channels. ACM filters have been demonstrated to effectively remove diesel exhaust particles while maintaining relatively low backpressure. Modeling approaches developed for more conventional ceramic filter materials, such as silicon carbide and cordierite, have been difficult to apply to ACM because of properties arising from its unique microstructure. Penetration of soot into the high-porosity region of projecting crystal structures leads to a somewhat extended depth filtration mode, but with less dramatic increases in pressure drop than are normally observed during depth filtration in cordierite or silicon carbide filters. Another consequence is greater contact between the soot and …
Date: August 1, 2010
Creator: Stewart, Mark L.; Gallant, Thomas R.; Kim, Do Heui; Maupin, Gary D. & Zelenyuk, Alla
Object Type: Report
System: The UNT Digital Library
Beam dynamics simulations of the NML photoinjector at Fermilab (open access)

Beam dynamics simulations of the NML photoinjector at Fermilab

Fermilab is currently constructing a superconducting RF (SRF) test linear accelerator at the New Muon Lab (NML). Besides testing SRF accelerating modules for ILC and Project-X, NML will also eventually support a variety of advanced accelerator R&D experiments. The NML incorporates a 40 MeV photoinjector capable of providing electron bunches with variable parameters. The photoinjector is based on the 1+1/2 cell DESY-type gun followed by two superconducting cavities. It also includes a magnetic bunch compressor, a round-to-flat beam transformer and a low-energy experimental area for beam physics experiments and beam diagnostics R&D. In this paper, we explore, via beam dynamics simulations, the performance of the photoinjector for different operating scenarios.
Date: August 1, 2010
Creator: Piot, P.; U., /Fermilab /Northern Illinois; Sun, Y. E.; Church, M. & /Fermilab
Object Type: Article
System: The UNT Digital Library
Thermal Storage and Advanced Heat Transfer Fluids (Fact Sheet) (open access)

Thermal Storage and Advanced Heat Transfer Fluids (Fact Sheet)

Fact sheet describing NREL CSP Program capabilities in the area of thermal storage and advanced heat transfer fluids: measuring thermophysical properties, measuring fluid flow and heat transfer, and simulating flow of thermal energy and fluid.
Date: August 1, 2010
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Lessons Learned From Developing Reactor Pressure Vessel Steel Embrittlement Database (open access)

Lessons Learned From Developing Reactor Pressure Vessel Steel Embrittlement Database

Materials behaviors caused by neutron irradiation under fission and/or fusion environments can be little understood without practical examination. Easily accessible material information system with large material database using effective computers is necessary for design of nuclear materials and analyses or simulations of the phenomena. The developed Embrittlement Data Base (EDB) at ORNL is this comprehensive collection of data. EDB database contains power reactor pressure vessel surveillance data, the material test reactor data, foreign reactor data (through bilateral agreements authorized by NRC), and the fracture toughness data. The lessons learned from building EDB program and the associated database management activity regarding Material Database Design Methodology, Architecture and the Embedded QA Protocol are described in this report. The development of IAEA International Database on Reactor Pressure Vessel Materials (IDRPVM) and the comparison of EDB database and IAEA IDRPVM database are provided in the report. The recommended database QA protocol and database infrastructure are also stated in the report.
Date: August 1, 2010
Creator: Wang, Jy-An John
Object Type: Report
System: The UNT Digital Library
High precision tune and coupling measurements and tune/coupling feedback in RHIC (open access)

High precision tune and coupling measurements and tune/coupling feedback in RHIC

Precision measurement and control of the betatron tunes and betatron coupling in RHIC are required for establishing and maintaining both good operating conditions and, particularly during the ramp to high beam energies, high proton beam polarization. While the proof-of-principle for simultaneous tune and coupling feedback was successfully demonstrated earlier, routine application of these systems has only become possible recently. Following numerous modifications for improved measurement resolution and feedback control, the time required to establish full-energy beams with the betatron tunes and coupling regulated by feedback was reduced from several weeks to a few hours. A summary of these improvements, select measurements benefitting from the improved resolution and a review of system performance are the subject of this report.
Date: August 1, 2010
Creator: Minty, M.; Curcio, A.; Dawson, C.; Degen, C.; Luo, Y.; Marr, G. et al.
Object Type: Report
System: The UNT Digital Library
Present Limits on the Precision of SM Predictions for Jet Energies (open access)

Present Limits on the Precision of SM Predictions for Jet Energies

We investigate the impact of theoretical uncertainties on the accuracy of measurements involving hadronic jets. The analysis is performed using events with a Z boson and a single jet observed in p{bar p} collisions at {radical}s = 1.96 TeV in 4.6 fb{sup -1} of data from the Collider Detector at Fermilab (CDF). The transverse momenta (p{sub T}) of the jet and the boson should balance each other due to momentum conservation in the plane transverse to the direction of the p and {bar p} beams. We evaluate the dependence of the measured p{sub T}-balance on theoretical uncertainties associated with initial and final state radiation, choice of renormalization and factorization scales, parton distribution functions, jet-parton matching, calculations of matrix elements, and parton showering. We find that the uncertainty caused by parton showering at large angles is the largest amongst the listed uncertainties. The proposed method can be re-applied at the LHC experiments to investigate and evaluate the uncertainties on the predicted jet energies. The distributions produced at the CDF environment are intended for comparison to those from modern event generators and new tunes of parton showering.
Date: August 1, 2010
Creator: Paramonov, A. A.; Canelli, F.; D'Onofrio, M.; Frisch, H. J. & Mrenna, S.
Object Type: Article
System: The UNT Digital Library
Basis for NGNP Reactor Design Down-Selection (open access)

Basis for NGNP Reactor Design Down-Selection

The purpose of this paper is to identify the extent of technology development, design and licensing maturity anticipated to be required to credibly identify differences that could make a technical choice practical between the prismatic and pebble bed reactor designs. This paper does not address a business decision based on the economics, business model and resulting business case since these will vary based on the reactor application. The selection of the type of reactor, the module ratings, the number of modules, the configuration of the balance of plant and other design selections will be made on the basis of optimizing the Business Case for the application. These are not decisions that can be made on a generic basis.
Date: August 1, 2010
Creator: Demick, L. E.
Object Type: Report
System: The UNT Digital Library
First Demonstration of the Echo-Enabled Harmonic Generation Technique for Short-Wavelength Seeded Free Electron Lasers (open access)

First Demonstration of the Echo-Enabled Harmonic Generation Technique for Short-Wavelength Seeded Free Electron Lasers

We report the first experimental demonstration of the echo-enabled harmonic generation (EEHG) technique which holds great promise for generation of high power, fully coherent short-wavelength radiation. In this experiment, coherent radiation at the 3rd and 4th harmonic of the second seed laser is generated from the so-called beam echo effect. The experiment confirms the physics behind this technique and paves the way for applying the EEHG technique for seeded x-ray free electron lasers.
Date: August 25, 2010
Creator: Xiang, D.; Colby, E.; Dunning, M.; Gilevich, S.; Hast, C.; Jobe, K. et al.
Object Type: Article
System: The UNT Digital Library
A Direct Top-Quark Width Measurement from Lepton + Jets Events at CDF II (open access)

A Direct Top-Quark Width Measurement from Lepton + Jets Events at CDF II

We present a measurement of the top-quark width using t{bar t} events produced in p{bar p} collisions at Fermilab's Tevatron collider and collected by the CDF II detector. In the mode where the top quark decays to a W boson and a bottom quark, we select events in which one W decays leptonically and the other hadronically (lepton + jets channel) . From a data sample corresponding to 4.3 fb{sup -1} of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of W boson that decays hadronically are reconstructed for each event and compared with templates of different top-quark widths ({Lambda}{sub t}) and deviations from nominal jet energy scale ({Delta}{sub JES}) to perform a simultaneous fit for both parameters, where {Delta}{sub JES} is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of {Lambda}{sub t} < 7.6 GeV and a two-sided 68% CL interval of 0.3 GeV < {Lambda}{sub t} < 4.4 GeV for a top-quark mass of 172.5 GeV/c{sup 2}, which are consistant with the standard model prediction. This is the first direct measurement of {Lambda}{sub t} to …
Date: August 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Object Type: Article
System: The UNT Digital Library
Migratory Behavior and Survival of Juvenile Salmonids in the Lower Columbia River and Estuary in 2009 (open access)

Migratory Behavior and Survival of Juvenile Salmonids in the Lower Columbia River and Estuary in 2009

The study reported herein was funded as part of the Anadromous Fish Evaluation Program, which is managed by the U.S. Army Corps of Engineers (USACE). The Anadromous Fish Evaluation Program study code is EST P 02 01: A Study of Salmonid Survival and Behavior through the Columbia River Estuary Using Acoustic Tags. The study was conducted by the Pacific Northwest National Laboratory (PNNL) and National Oceanic and Atmospheric Administration (NOAA) Fisheries for the USACE Portland District. Estimated survival of acoustic-tagged juvenile Chinook salmon and steelhead through the lower Columbia River and estuary in 2009 was lowest in the final 50 km of the estuary. Probability of survival was relatively high (>0.90) for yearling and subyearling Chinook salmon from the Bonneville Dam forebay (rkm 236) to Three-tree Point (rkm 49.6). Survival of juvenile Chinook salmon declined sharply through the lower 50 km of the estuary. Acoustic-tagged steelhead smolts did not survive as well as juvenile Chinook salmon between Bonneville Dam and the mouth of the Columbia River. Steelhead survival began to decline farther upstream (at rkm 86) relative to that of the Chinook salmon stocks. Subyearling Chinook salmon survival decreased markedly as the season progressed. It remains to be determined whether …
Date: August 1, 2010
Creator: McMichael, Geoffrey A.; Harnish, Ryan A.; Bellgraph, Brian J.; Carter, Jessica A.; Ham, Kenneth D.; Titzler, P. Scott et al.
Object Type: Report
System: The UNT Digital Library
In-situ Creep Testing Capability Development for Advanced Test Reactor (open access)

In-situ Creep Testing Capability Development for Advanced Test Reactor

Creep is the slow, time-dependent strain that occurs in a material under a constant strees (or load) at high temperature. High temperature is a relative term, dependent on the materials being evaluated. A typical creep curve is shown in Figure 1-1. In a creep test, a constant load is applied to a tensile specimen maintained at a constant temperature. Strain is then measured over a period of time. The slope of the curve, identified in the figure below, is the strain rate of the test during Stage II or the creep rate of the material. Primary creep, Stage I, is a period of decreasing creep rate due to work hardening of the material. Primary creep is a period of primarily transient creep. During this period, deformation takes place and the resistance to creep increases until Stage II, Secondary creep. Stage II creep is a period with a roughly constant creep rate. Stage II is referred to as steady-state creep because a balance is achieved between the work hardening and annealing (thermal softening) processes. Tertiary creep, Stage III, occurs when there is a reduction in cross sectional area due to necking or effective reduction in area due to internal void formation; …
Date: August 1, 2010
Creator: Kim, B. G.; Rempe, J. L.; Knudson, D. L.; Condie, K. G. & Sencer, B. H.
Object Type: Report
System: The UNT Digital Library
Essence of the Vacuum Quark Condensate (open access)

Essence of the Vacuum Quark Condensate

We show that the chiral-limit vacuum quark condensate is qualitatively equivalent to the pseudoscalar meson leptonic decay constant in the sense that they are both obtained as the chiral-limit value of well-defined gauge-invariant hadron-to-vacuum transition amplitudes that possess a spectral representation in terms of the current-quark mass. Thus, whereas it might sometimes be convenient to imagine otherwise, neither is essentially a constant mass-scale that fills all spacetime. This means, in particular, that the quark condensate can be understood as a property of hadrons themselves, which is expressed, for example, in their Bethe-Salpeter or light-front wavefunctions.
Date: August 25, 2010
Creator: Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Roberts, Craig D.; /Argonne, PHY /Peking U.; Shrock, Robert; /YITP, Stony Brook et al.
Object Type: Article
System: The UNT Digital Library
License Structure for Multi-Module Facilities (open access)

License Structure for Multi-Module Facilities

The Next Generation Nuclear Plant (NGNP) Project is intended to be the prototype for multi-module commercial high temperature gas reactors (HTGRs) for process heat and/or electricity generation. Part of the objectives of the project are to establish the conditions that would govern or enhance the design, licensing, construction and operation of numerous, modular nuclear plants, particularly suited for industrial applications or that could reduce the risk of such projects. A determination is desired regarding whether a multi-module reactor plant can be licensed with a single Nuclear Regulatory Commission (NRC) review, hearing, and safety evaluation report. If it is determined that a multi-modular reactor plant can be licensed under a single review/hearing process, the structure and the duration of the license for each module will also need to be determined. The purpose of this paper is to describe for the NRC the NGNP position on these two issues and obtain either NRC general concurrence or comments on the approach to these issues. While the current NGNP planning provides for only a single reactor module, the project is intended to provide the basis and establish a licensing framework that can be used by future commercial HTGRs and other reactor designs, including a …
Date: August 1, 2010
Creator: Hicks, Thomas
Object Type: Report
System: The UNT Digital Library
A framework for graph-based synthesis, analysis, and visualization of HPC cluster job data. (open access)

A framework for graph-based synthesis, analysis, and visualization of HPC cluster job data.

The monitoring and system analysis of high performance computing (HPC) clusters is of increasing importance to the HPC community. Analysis of HPC job data can be used to characterize system usage and diagnose and examine failure modes and their effects. This analysis is not straightforward, however, due to the complex relationships that exist between jobs. These relationships are based on a number of factors, including shared compute nodes between jobs, proximity of jobs in time, etc. Graph-based techniques represent an approach that is particularly well suited to this problem, and provide an effective technique for discovering important relationships in job queuing and execution data. The efficacy of these techniques is rooted in the use of a semantic graph as a knowledge representation tool. In a semantic graph job data, represented in a combination of numerical and textual forms, can be flexibly processed into edges, with corresponding weights, expressing relationships between jobs, nodes, users, and other relevant entities. This graph-based representation permits formal manipulation by a number of analysis algorithms. This report presents a methodology and software implementation that leverages semantic graph-based techniques for the system-level monitoring and analysis of HPC clusters based on job queuing and execution data. Ontology development …
Date: August 1, 2010
Creator: Mayo, Jackson R.; Kegelmeyer, W. Philip, Jr.; Wong, Matthew H.; Pebay, Philippe Pierre; Gentile, Ann C.; Thompson, David C. et al.
Object Type: Report
System: The UNT Digital Library
Control system devices : architectures and supply channels overview. (open access)

Control system devices : architectures and supply channels overview.

This report describes a research project to examine the hardware used in automated control systems like those that control the electric grid. This report provides an overview of the vendors, architectures, and supply channels for a number of control system devices. The research itself represents an attempt to probe more deeply into the area of programmable logic controllers (PLCs) - the specialized digital computers that control individual processes within supervisory control and data acquisition (SCADA) systems. The report (1) provides an overview of control system networks and PLC architecture, (2) furnishes profiles for the top eight vendors in the PLC industry, (3) discusses the communications protocols used in different industries, and (4) analyzes the hardware used in several PLC devices. As part of the project, several PLCs were disassembled to identify constituent components. That information will direct the next step of the research, which will greatly increase our understanding of PLC security in both the hardware and software areas. Such an understanding is vital for discerning the potential national security impact of security flaws in these devices, as well as for developing proactive countermeasures.
Date: August 1, 2010
Creator: Trent, Jason; Atkins, William Dee; Schwartz, Moses Daniel & Mulder, John C.
Object Type: Report
System: The UNT Digital Library
The DAFT/FADA survey. I.Photometric redshifts along lines of sight to clusters in the z=[0.4,0.9] interval (open access)

The DAFT/FADA survey. I.Photometric redshifts along lines of sight to clusters in the z=[0.4,0.9] interval

As a contribution to the understanding of the dark energy concept, the Dark energy American French Team (DAFT, in French FADA) has started a large project to characterize statistically high redshift galaxy clusters, infer cosmological constraints from Weak Lensing Tomography, and understand biases relevant for constraining dark energy and cluster physics in future cluster and cosmological experiments. Aims. The purpose of this paper is to establish the basis of reference for the photo-z determination used in all our subsequent papers, including weak lensing tomography studies. This project is based on a sample of 91 high redshift (z {ge} 0.4), massive ({approx}> 3 x 10{sup 14} M{sub {circle_dot}}) clusters with existing HST imaging, for which we are presently performing complementary multi-wavelength imaging. This allows us in particular to estimate spectral types and determine accurate photometric redshifts for galaxies along the lines of sight to the first ten clusters for which all the required data are available down to a limit of I{sub AB} = 24./24.5 with the LePhare software. The accuracy in redshift is of the order of 0.05 for the range 0.2 {le} z {le} 1.5. We verified that the technique applied to obtain photometric redshifts works well by comparing …
Date: August 1, 2010
Creator: Guennou, L.; /Northwestern U. /Marseille, Lab. Astrophys.; Adami, C.; /Marseille, Lab. Astrophys.; Ulmer, M.P.; /Northwestern U. /Marseille, Lab. Astrophys. et al.
Object Type: Article
System: The UNT Digital Library