sources control techniques: Topics by Science.gov

Sample records for sources control techniques

Control Techniques for Particulate Air Pollutants.

ERIC Educational Resources Information Center

National Air Pollution Control Administration (DHEW), Washington, DC.

Included is a comprehensive review of the approaches commonly recommended for controlling the sources of particulate air pollution. Not all possible combinations of control techniques that might bring about more stringent control of each individual source are reviewed. The many agricultural, commercial, domestic, industrial, and municipal…
Monitoring by Control Technique - Cyclone

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about cyclone control techniques used to reduce pollutant emissions.
Monitoring by Control Technique - Condensers

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about condenser control techniques used to reduce pollutant emissions.
Floating-point scaling technique for sources separation automatic gain control

NASA Astrophysics Data System (ADS)

Fermas, A.; Belouchrani, A.; Ait-Mohamed, O.

2012-07-01

Based on the floating-point representation and taking advantage of scaling factor indetermination in blind source separation (BSS) processing, we propose a scaling technique applied to the separation matrix, to avoid the saturation or the weakness in the recovered source signals. This technique performs an automatic gain control in an on-line BSS environment. We demonstrate the effectiveness of this technique by using the implementation of a division-free BSS algorithm with two inputs, two outputs. The proposed technique is computationally cheaper and efficient for a hardware implementation compared to the Euclidean normalisation.
Monitoring by Control Technique - Catalytic Oxidizer

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about catalytic oxidizer control techniques used to reduce pollutant emissions.
Monitoring by Control Technique - Thermal Oxidizer

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about thermal oxidizer control techniques used to reduce pollutant emissions.
Monitoring by Control Technique - Electrostatic Precipitators

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about electrostatic precipitator control techniques used to reduce pollutant emissions.
Monitoring by Control Technique - Fabric Filters

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about fabric filter control techniques used to reduce pollutant emissions.
Monitoring by Control Technique - Capture Systems

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about capture system control techniques used to reduce pollutant emissions.
Monitoring by Control Technique - Activated Carbon Adsorber

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about Activated Carbon Adsorber control techniques used to reduce pollutant emissions.
Monitoring by Control Technique - Electrified Filter Bed

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about electrified filter bed control techniques used to reduce pollutant emissions.
Monitoring by Control Technique - Compliant (Low/No VOC/HAP) Inks and Coatings

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about Compliant (Low/No VOC/HAP) Inks and Coatings control techniques used to reduce pollutant emissions.
[Demand for and the Development of Detection Techniques for Source of Schistosome Infection in China].

PubMed

Wang, Shi-ping; He, Xin; Zhou, Yun-fei

2015-12-01

Schistosomiasis is a type of zoonotic parasitosis that severely impairs human health. Rapid detection of infection sources is a key to the control of schistosomiasis. With the effective control of schistosomiasis in China, the detection techniques for infection sources have also been developed. The rate and the intensity of infection among humans and livestocks have been significantly decreased in China, as the control program has entered the transmission control stage in most of the endemic areas. Under this situation, the traditional etiological diagnosing techniques and common immunological methods can not afford rapid detection of infection sources of schistosomiasis. Instead, we are calling for detection methods with higher sensitivity, specificity and stability while being less time-consuming, more convenient and less costing. In recent years, many improved or novel detection methods have been applied for the epidemiological surveillance of schistosomiasis, such as the automatic scanning microscopic image acquisition system, PCR-ELISA, immunosensors, loop-mediated isothermal amplification, etc. The development of new monitoring techniques can facilitate rapid detection of schistosome infection sources in endemic areas.
78 FR 16783 - Approval and Promulgation of Implementation Plans; Georgia; Control Techniques Guidelines and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-19

... Promulgation of Implementation Plans; Georgia; Control Techniques Guidelines and Reasonably Available Control...), related to reasonably available control technology (RACT) requirements. This correcting amendment corrects... October 21, 2009, SIP submittal for certain source categories for which EPA has issued control technique...
40 CFR 52.2572 - Approval status.

Code of Federal Regulations, 2012 CFR

2012-07-01

... adoption and submittal of RACT requirements on: (1) Group III Control Techniques Guideline sources within 1 year after January 1st following the issuance of each Group III control technique guideline; and (2) Major (actual emissions equal or greater than 100 tons VOC per year) non-control technique guideline...
40 CFR 52.2572 - Approval status.

Code of Federal Regulations, 2011 CFR

2011-07-01

... adoption and submittal of RACT requirements on: (1) Group III Control Techniques Guideline sources within 1 year after January 1st following the issuance of each Group III control technique guideline; and (2) Major (actual emissions equal or greater than 100 tons VOC per year) non-control technique guideline...
Efficient Development of High Fidelity Structured Volume Grids for Hypersonic Flow Simulations

NASA Technical Reports Server (NTRS)

Alter, Stephen J.

2003-01-01

A new technique for the control of grid line spacing and intersection angles of a structured volume grid, using elliptic partial differential equations (PDEs) is presented. Existing structured grid generation algorithms make use of source term hybridization to provide control of grid lines, imposing orthogonality implicitly at the boundary and explicitly on the interior of the domain. A bridging function between the two types of grid line control is typically used to blend the different orthogonality formulations. It is shown that utilizing such a bridging function with source term hybridization can result in the excessive use of computational resources and diminishes robustness. A new approach, Anisotropic Lagrange Based Trans-Finite Interpolation (ALBTFI), is offered as a replacement to source term hybridization. The ALBTFI technique captures the essence of the desired grid controls while improving the convergence rate of the elliptic PDEs when compared with source term hybridization. Grid generation on a blunt cone and a Shuttle Orbiter is used to demonstrate and assess the ALBTFI technique, which is shown to be as much as 50% faster, more robust, and produces higher quality grids than source term hybridization.
Active room compensation for sound reinforcement using sound field separation techniques.

PubMed

Heuchel, Franz M; Fernandez-Grande, Efren; Agerkvist, Finn T; Shabalina, Elena

2018-03-01

This work investigates how the sound field created by a sound reinforcement system can be controlled at low frequencies. An indoor control method is proposed which actively absorbs the sound incident on a reflecting boundary using an array of secondary sources. The sound field is separated into incident and reflected components by a microphone array close to the secondary sources, enabling the minimization of reflected components by means of optimal signals for the secondary sources. The method is purely feed-forward and assumes constant room conditions. Three different sound field separation techniques for the modeling of the reflections are investigated based on plane wave decomposition, equivalent sources, and the Spatial Fourier transform. Simulations and an experimental validation are presented, showing that the control method performs similarly well at enhancing low frequency responses with the three sound separation techniques. Resonances in the entire room are reduced, although the microphone array and secondary sources are confined to a small region close to the reflecting wall. Unlike previous control methods based on the creation of a plane wave sound field, the investigated method works in arbitrary room geometries and primary source positions.
Programmable solid state atom sources for nanofabrication.

PubMed

Han, Han; Imboden, Matthias; Stark, Thomas; del Corro, Pablo G; Pardo, Flavio; Bolle, Cristian A; Lally, Richard W; Bishop, David J

2015-06-28

In this paper we discuss the development of a MEMS-based solid state atom source that can provide controllable atom deposition ranging over eight orders of magnitude, from ten atoms per square micron up to hundreds of atomic layers, on a target ∼1 mm away. Using a micron-scale silicon plate as a thermal evaporation source we demonstrate the deposition of indium, silver, gold, copper, iron, aluminum, lead and tin. Because of their small sizes and rapid thermal response times, pulse width modulation techniques are a powerful way to control the atomic flux. Pulsing the source with precise voltages and timing provides control in terms of when and how many atoms get deposited. By arranging many of these devices into an array, one has a multi-material, programmable solid state evaporation source. These micro atom sources are a complementary technology that can enhance the capability of a variety of nano-fabrication techniques.
Aircraft Drag Prediction and Reduction

DTIC Science & Technology

1985-07-01

Figure 10 with their subsources. The major source groups are the airfiame noise sources, the propulsion system noise sources, and the lamirar-flow control ...the emerging areas of non -planar geometry and large-eddy alteration. Turbulent control techniques for air generally result in modest (but...17. 57. Ketchem, Jeffery J.; and Velkoff, Henry R.: An Experimental Investigation of the Effect of Electrically Induced Controlled Frequency

Monitoring Knowledge Base (MKB)

EPA Pesticide Factsheets

The Monitoring Knowledge Base (MKB) is a compilation of emissions measurement and monitoring techniques associated with air pollution control devices, industrial process descriptions, and permitting techniques, including flexible permit development. Using MKB, one can gain a comprehensive understanding of emissions sources, control devices, and monitoring techniques, enabling one to determine appropriate permit terms and conditions.
Techniques for Tracking, Evaluating, and Reporting the Implementation of Nonpoint Source Control Measures - Forestry

EPA Pesticide Factsheets

This guidance is intended to assist state, regional, and local environmental professionals in tracking the implementation of best management practices (BMPs) used to control nonpoint source pollution generated by forestry practices.
Monitoring by Control Technique - Wet Scrubber For Particulate Matter

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about Wet Scrubber For Particulate Matter controls used to reduce pollutant emissions.
75 FR 59179 - Approval and Promulgation of Air Quality Implementation Plans; Maryland; Adoption of Control...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-27

... (RACT) for sources covered by EPA's Control Techniques Guidelines (CTG) for flexible packaging printing... Promulgation of Air Quality Implementation Plans; Maryland; Adoption of Control Techniques Guidelines for Flexible Packaging Printing AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY...
Assessment and control of spacecraft electromagnetic interference

NASA Technical Reports Server (NTRS)

1972-01-01

Design criteria are presented to provide guidance in assessing electromagnetic interference from onboard sources and establishing requisite control in spacecraft design, development, and testing. A comprehensive state-of-the-art review is given which covers flight experience, sources and transmission of electromagnetic interference, susceptible equipment, design procedure, control techniques, and test methods.
SOURCE MANAGEMENT AND CONTROL TECHNOLOGIES

EPA Science Inventory

The options for pollution abatement in WWF can be implemented at the source by land management and pollution prevention techniques, in the collection system, offline by storage, or in a treatment plant. An integrated system that combines prevention, control, and treatment has of...
Time domain localization technique with sparsity constraint for imaging acoustic sources

NASA Astrophysics Data System (ADS)

Padois, Thomas; Doutres, Olivier; Sgard, Franck; Berry, Alain

2017-09-01

This paper addresses source localization technique in time domain for broadband acoustic sources. The objective is to accurately and quickly detect the position and amplitude of noise sources in workplaces in order to propose adequate noise control options and prevent workers hearing loss or safety risk. First, the generalized cross correlation associated with a spherical microphone array is used to generate an initial noise source map. Then a linear inverse problem is defined to improve this initial map. Commonly, the linear inverse problem is solved with an l2 -regularization. In this study, two sparsity constraints are used to solve the inverse problem, the orthogonal matching pursuit and the truncated Newton interior-point method. Synthetic data are used to highlight the performances of the technique. High resolution imaging is achieved for various acoustic sources configurations. Moreover, the amplitudes of the acoustic sources are correctly estimated. A comparison of computation times shows that the technique is compatible with quasi real-time generation of noise source maps. Finally, the technique is tested with real data.
HANDBOOK: CONTROL TECHNIQUES FOR HAZARDOUS AIR POLLUTANTS

EPA Science Inventory

This manual is a revision of the first (1986) edition of the Handbook: Control Technologies for Hazardous Air Pollutants, which incorporated information from numerous sources into a single, self-contained reference source focusing on the design and cost of VOC and partic...
Estimation of point source fugitive emission rates from a single sensor time series: a conditionally-sampled Gaussian plume reconstruction

EPA Science Inventory

This paper presents a technique for determining the trace gas emission rate from a point source. The technique was tested using data from controlled methane release experiments and from measurement downwind of a natural gas production facility in Wyoming. Concentration measuremen...
One way Doppler Extractor. Volume 2: Digital VCO technique

NASA Technical Reports Server (NTRS)

Nossen, E. J.; Starner, E. R.

1974-01-01

A feasibility analysis and trade-offs for a one-way Doppler extractor using digital VCO techniques is presented. The method of Doppler measurement involves the use of a digital phase lock loop; once this loop is locked to the incoming signal, the precise frequency and hence the Doppler component can be determined directly from the contents of the digital control register. The only serious error source is due to internally generated noise. Techniques are presented for minimizing this error source and achieving an accuracy of 0.01 Hz in a one second averaging period. A number of digitally controlled oscillators were analyzed from a performance and complexity point of view. The most promising technique uses an arithmetic synthesizer as a digital waveform generator.
A study of interior noise levels, noise sources and transmission paths in light aircraft

NASA Technical Reports Server (NTRS)

Hayden, R. E.; Murray, B. S.; Theobald, M. A.

1983-01-01

The interior noise levels and spectral characteristics of 18 single-and twin-engine propeller-driven light aircraft, and source-path diagnosis of a single-engine aircraft which was considered representative of a large part of the fleet were studied. The purpose of the flight surveys was to measure internal noise levels and identify principal noise sources and paths under a carefully controlled and standardized set of flight procedures. The diagnostic tests consisted of flights and ground tests in which various parts of the aircraft, such as engine mounts, the engine compartment, exhaust pipe, individual panels, and the wing strut were instrumented to determine source levels and transmission path strengths using the transfer function technique. Predominant source and path combinations are identified. Experimental techniques are described. Data, transfer function calculations to derive source-path contributions to the cabin acoustic environment, and implications of the findings for noise control design are analyzed.
Photochemical grid model implementation and application of VOC, NOx, and O3 source apportionment

EPA Science Inventory

For the purposes of developing optimal emissions control strategies, efficient approaches are needed to identify the major sources or groups of sources that contribute to elevated ozone (O3) concentrations. Source-based apportionment techniques implemented in photochemical grid m...
Fuzzy logic controller versus classical logic controller for residential hybrid solar-wind-storage energy system

NASA Astrophysics Data System (ADS)

Derrouazin, A.; Aillerie, M.; Mekkakia-Maaza, N.; Charles, J. P.

2016-07-01

Several researches for management of diverse hybrid energy systems and many techniques have been proposed for robustness, savings and environmental purpose. In this work we aim to make a comparative study between two supervision and control techniques: fuzzy and classic logics to manage the hybrid energy system applied for typical housing fed by solar and wind power, with rack of batteries for storage. The system is assisted by the electric grid during energy drop moments. A hydrogen production device is integrated into the system to retrieve surplus energy production from renewable sources for the household purposes, intending the maximum exploitation of these sources over years. The models have been achieved and generated signals for electronic switches command of proposed both techniques are presented and discussed in this paper.
40 CFR 52.1168 - Certification of no sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1168... sources are located in the Commonwealth which are covered by the following Control Techniques Guidelines...
40 CFR 52.1168 - Certification of no sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1168... sources are located in the Commonwealth which are covered by the following Control Techniques Guidelines...
40 CFR 52.1168 - Certification of no sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1168... sources are located in the Commonwealth which are covered by the following Control Techniques Guidelines...
40 CFR 52.1168 - Certification of no sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1168... sources are located in the Commonwealth which are covered by the following Control Techniques Guidelines...
General Aviation Interior Noise. Part 3; Noise Control Measure Evaluation

NASA Technical Reports Server (NTRS)

Unruh, James F.; Till, Paul D.; Palumbo, Daniel L. (Technical Monitor)

2002-01-01

The work reported herein is an extension to the work accomplished under NASA Grant NAG1-2091 on the development of noise/source/path identification techniques for single engine propeller driven General Aviation aircraft. The previous work developed a Conditioned Response Analysis (CRA) technique to identify potential noise sources that contributed to the dominating tonal responses within the aircraft cabin. The objective of the present effort was to improve and verify the findings of the CRA and develop and demonstrate noise control measures for single engine propeller driven General Aviation aircraft.
Techniques for detection and localization of weak hippocampal and medial frontal sources using beamformers in MEG.

PubMed

Mills, Travis; Lalancette, Marc; Moses, Sandra N; Taylor, Margot J; Quraan, Maher A

2012-07-01

Magnetoencephalography provides precise information about the temporal dynamics of brain activation and is an ideal tool for investigating rapid cognitive processing. However, in many cognitive paradigms visual stimuli are used, which evoke strong brain responses (typically 40-100 nAm in V1) that may impede the detection of weaker activations of interest. This is particularly a concern when beamformer algorithms are used for source analysis, due to artefacts such as "leakage" of activation from the primary visual sources into other regions. We have previously shown (Quraan et al. 2011) that we can effectively reduce leakage patterns and detect weak hippocampal sources by subtracting the functional images derived from the experimental task and a control task with similar stimulus parameters. In this study we assess the performance of three different subtraction techniques. In the first technique we follow the same post-localization subtraction procedures as in our previous work. In the second and third techniques, we subtract the sensor data obtained from the experimental and control paradigms prior to source localization. Using simulated signals embedded in real data, we show that when beamformers are used, subtraction prior to source localization allows for the detection of weaker sources and higher localization accuracy. The improvement in localization accuracy exceeded 10 mm at low signal-to-noise ratios, and sources down to below 5 nAm were detected. We applied our techniques to empirical data acquired with two different paradigms designed to evoke hippocampal and frontal activations, and demonstrated our ability to detect robust activations in both regions with substantial improvements over image subtraction. We conclude that removal of the common-mode dominant sources through data subtraction prior to localization further improves the beamformer's ability to project the n-channel sensor-space data to reveal weak sources of interest and allows more accurate localization.
Fuzzy logic controller versus classical logic controller for residential hybrid solar-wind-storage energy system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Derrouazin, A., E-mail: derrsid@gmail.com; Université de Lorraine, LMOPS, EA 4423, 57070 Metz; CentraleSupélec, LMOPS, 57070 Metz

Several researches for management of diverse hybrid energy systems and many techniques have been proposed for robustness, savings and environmental purpose. In this work we aim to make a comparative study between two supervision and control techniques: fuzzy and classic logics to manage the hybrid energy system applied for typical housing fed by solar and wind power, with rack of batteries for storage. The system is assisted by the electric grid during energy drop moments. A hydrogen production device is integrated into the system to retrieve surplus energy production from renewable sources for the household purposes, intending the maximum exploitationmore » of these sources over years. The models have been achieved and generated signals for electronic switches command of proposed both techniques are presented and discussed in this paper.« less

Status and Needs Research for On-line Monitoring of VOCs Emissions from Stationary Sources

NASA Astrophysics Data System (ADS)

Zhou, Gang; Wang, Qiang; Zhong, Qi; Zhao, Jinbao; Yang, Kai

2018-01-01

Based on atmospheric volatile organic compounds (VOCs) pollution control requirements during the twelfth-five year plan and the current status of monitoring and management at home and abroad, instrumental architecture and technical characteristics of continuous emission monitoring systems (CEMS) for VOCs emission from stationary sources are investigated and researched. Technological development needs of VOCs emission on-line monitoring techniques for stationary sources in china are proposed from the system sampling pretreatment technology and analytical measurement techniques.
Reduction of Helicopter Blade-Vortex Interaction Noise by Active Rotor Control Technology

NASA Technical Reports Server (NTRS)

Yu, Yung H.; Gmelin, Bernd; Splettstoesser, Wolf; Brooks, Thomas F.; Philippe, Jean J.; Prieur, Jean

1997-01-01

Helicopter blade-vortex interaction noise is one of the most severe noise sources and is very important both in community annoyance and military detection. Research over the decades has substantially improved basic physical understanding of the mechanisms generating rotor blade-vortex interaction noise and also of controlling techniques, particularly using active rotor control technology. This paper reviews active rotor control techniques currently available for rotor blade vortex interaction noise reduction, including higher harmonic pitch control, individual blade control, and on-blade control technologies. Basic physical mechanisms of each active control technique are reviewed in terms of noise reduction mechanism and controlling aerodynamic or structural parameters of a blade. Active rotor control techniques using smart structures/materials are discussed, including distributed smart actuators to induce local torsional or flapping deformations, Published by Elsevier Science Ltd.
Relating to monitoring ion sources

DOEpatents

Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore; Bounds, John Alan

2002-01-01

The apparatus and method provide techniques for monitoring the position on alpha contamination in or on items or locations. The technique is particularly applicable to pipes, conduits and other locations to which access is difficult. The technique uses indirect monitoring of alpha emissions by detecting ions generated by the alpha emissions. The medium containing the ions is moved in a controlled manner frog in proximity with the item or location to the detecting unit and the signals achieved over time are used to generate alpha source position information.
An improved DPSM technique for modelling ultrasonic fields in cracked solids

NASA Astrophysics Data System (ADS)

Banerjee, Sourav; Kundu, Tribikram; Placko, Dominique

2007-04-01

In recent years Distributed Point Source Method (DPSM) is being used for modelling various ultrasonic, electrostatic and electromagnetic field modelling problems. In conventional DPSM several point sources are placed near the transducer face, interface and anomaly boundaries. The ultrasonic or the electromagnetic field at any point is computed by superimposing the contributions of different layers of point sources strategically placed. The conventional DPSM modelling technique is modified in this paper so that the contributions of the point sources in the shadow region can be removed from the calculations. For this purpose the conventional point sources that radiate in all directions are replaced by Controlled Space Radiation (CSR) sources. CSR sources can take care of the shadow region problem to some extent. Complete removal of the shadow region problem can be achieved by introducing artificial interfaces. Numerically synthesized fields obtained by the conventional DPSM technique that does not give any special consideration to the point sources in the shadow region and the proposed modified technique that nullifies the contributions of the point sources in the shadow region are compared. One application of this research can be found in the improved modelling of the real time ultrasonic non-destructive evaluation experiments.
Model Predictive Control techniques with application to photovoltaic, DC Microgrid, and a multi-sourced hybrid energy system

NASA Astrophysics Data System (ADS)

Shadmand, Mohammad Bagher

Renewable energy sources continue to gain popularity. However, two major limitations exist that prevent widespread adoption: availability and variability of the electricity generated and the cost of the equipment. The focus of this dissertation is Model Predictive Control (MPC) for optimal sized photovoltaic (PV), DC Microgrid, and multi-sourced hybrid energy systems. The main considered applications are: maximum power point tracking (MPPT) by MPC, droop predictive control of DC microgrid, MPC of grid-interaction inverter, MPC of a capacitor-less VAR compensator based on matrix converter (MC). This dissertation firstly investigates a multi-objective optimization technique for a hybrid distribution system. The variability of a high-penetration PV scenario is also studied when incorporated into the microgrid concept. Emerging (PV) technologies have enabled the creation of contoured and conformal PV surfaces; the effect of using non-planar PV modules on variability is also analyzed. The proposed predictive control to achieve maximum power point for isolated and grid-tied PV systems speeds up the control loop since it predicts error before the switching signal is applied to the converter. The low conversion efficiency of PV cells means we want to ensure always operating at maximum possible power point to make the system economical. Thus the proposed MPPT technique can capture more energy compared to the conventional MPPT techniques from same amount of installed solar panel. Because of the MPPT requirement, the output voltage of the converter may vary. Therefore a droop control is needed to feed multiple arrays of photovoltaic systems to a DC bus in microgrid community. Development of a droop control technique by means of predictive control is another application of this dissertation. Reactive power, denoted as Volt Ampere Reactive (VAR), has several undesirable consequences on AC power system network such as reduction in power transfer capability and increase in transmission loss if not controlled appropriately. Inductive loads which operate with lagging power factor consume VARs, thus load compensation techniques by capacitor bank employment locally supply VARs needed by the load. Capacitors are highly unreliable components due to their failure modes and aging inherent. Approximately 60% of power electronic devices failure such as voltage-source inverter based static synchronous compensator (STATCOM) is due to the use of aluminum electrolytic DC capacitors. Therefore, a capacitor-less VAR compensation is desired. This dissertation also investigates a STATCOM capacitor-less reactive power compensation that uses only inductors combined with predictive controlled matrix converter.
Current Source Based on H-Bridge Inverter with Output LCL Filter

NASA Astrophysics Data System (ADS)

Blahnik, Vojtech; Talla, Jakub; Peroutka, Zdenek

2015-09-01

The paper deals with a control of current source with an LCL output filter. The controlled current source is realized as a single-phase inverter and output LCL filter provides low ripple of output current. However, systems incorporating LCL filters require more complex control strategies and there are several interesting approaches to the control of this type of converter. This paper presents the inverter control algorithm, which combines model based control with a direct current control based on resonant controllers and single-phase vector control. The primary goal is to reduce the current ripple and distortion under required limits and provides fast and precise control of output current. The proposed control technique is verified by measurements on the laboratory model.
A boundary element approach to optimization of active noise control sources on three-dimensional structures

NASA Technical Reports Server (NTRS)

Cunefare, K. A.; Koopmann, G. H.

1991-01-01

This paper presents the theoretical development of an approach to active noise control (ANC) applicable to three-dimensional radiators. The active noise control technique, termed ANC Optimization Analysis, is based on minimizing the total radiated power by adding secondary acoustic sources on the primary noise source. ANC Optimization Analysis determines the optimum magnitude and phase at which to drive the secondary control sources in order to achieve the best possible reduction in the total radiated power from the noise source/control source combination. For example, ANC Optimization Analysis predicts a 20 dB reduction in the total power radiated from a sphere of radius at a dimensionless wavenumber ka of 0.125, for a single control source representing 2.5 percent of the total area of the sphere. ANC Optimization Analysis is based on a boundary element formulation of the Helmholtz Integral Equation, and thus, the optimization analysis applies to a single frequency, while multiple frequencies can be treated through repeated analyses.
High-Resolution Fast-Neutron Spectrometry for Arms Control and Treaty Verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

David L. Chichester; James T. Johnson; Edward H. Seabury

2012-07-01

Many nondestructive nuclear analysis techniques have been developed to support the measurement needs of arms control and treaty verification, including gross photon and neutron counting, low- and high-resolution gamma spectrometry, time-correlated neutron measurements, and photon and neutron imaging. One notable measurement technique that has not been extensively studied to date for these applications is high-resolution fast-neutron spectrometry (HRFNS). Applied for arms control and treaty verification, HRFNS has the potential to serve as a complimentary measurement approach to these other techniques by providing a means to either qualitatively or quantitatively determine the composition and thickness of non-nuclear materials surrounding neutron-emitting materials.more » The technique uses the normally-occurring neutrons present in arms control and treaty verification objects of interest as an internal source of neutrons for performing active-interrogation transmission measurements. Most low-Z nuclei of interest for arms control and treaty verification, including 9Be, 12C, 14N, and 16O, possess fast-neutron resonance features in their absorption cross sections in the 0.5- to 5-MeV energy range. Measuring the selective removal of source neutrons over this energy range, assuming for example a fission-spectrum starting distribution, may be used to estimate the stoichiometric composition of intervening materials between the neutron source and detector. At a simpler level, determination of the emitted fast-neutron spectrum may be used for fingerprinting 'known' assemblies for later use in template-matching tests. As with photon spectrometry, automated analysis of fast-neutron spectra may be performed to support decision making and reporting systems protected behind information barriers. This paper will report recent work at Idaho National Laboratory to explore the feasibility of using HRFNS for arms control and treaty verification applications, including simulations and experiments, using fission-spectrum neutron sources to assess neutron transmission through composite low-Z attenuators.« less
Alternative control techniques document: NOx emissions from industrial/commercial/institutional (ICI) boilers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1994-03-01

Industrial, commercial, and institutional (ICI) boilers have been identified as a category that emits more than 25 tons of oxides of nitrogen (NOx) per year. This alternative control techniques (ACT) document provides technical information for use by State and local agencies to develop and implement regulatory programs to control NOx emissions from ICI boilers. Additional ACT documents are being developed for other stationary source categories. Chapter 2 summarizes the findings of this study. Chapter 3 presents information on the ICI boiler types, fuels, operation, and industry applications. Chapter 4 discusses NOx formation and uncontrolled NOx emission factors. Chapter 5 coversmore » alternative control techniques and achievable controlled emission levels. Chapter 6 presents the cost and cost effectiveness of each control technique. Chapter 7 describes environmental and energy impacts associated with implementing the NOx control techniques. Finally, Appendices A through G provide the detailed data used in this study to evaluate uncontrolled and controlled emissions and the costs of controls for several retrofit scenarios.« less
Monitoring Information By Industry - Printing and Publishing

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about control techniques used to reduce pollutant emissions in the printing and publishing industry.
Statistical atmospheric inversion of local gas emissions by coupling the tracer release technique and local-scale transport modelling: a test case with controlled methane emissions

NASA Astrophysics Data System (ADS)

Ars, Sébastien; Broquet, Grégoire; Yver Kwok, Camille; Roustan, Yelva; Wu, Lin; Arzoumanian, Emmanuel; Bousquet, Philippe

2017-12-01

This study presents a new concept for estimating the pollutant emission rates of a site and its main facilities using a series of atmospheric measurements across the pollutant plumes. This concept combines the tracer release method, local-scale atmospheric transport modelling and a statistical atmospheric inversion approach. The conversion between the controlled emission and the measured atmospheric concentrations of the released tracer across the plume places valuable constraints on the atmospheric transport. This is used to optimise the configuration of the transport model parameters and the model uncertainty statistics in the inversion system. The emission rates of all sources are then inverted to optimise the match between the concentrations simulated with the transport model and the pollutants' measured atmospheric concentrations, accounting for the transport model uncertainty. In principle, by using atmospheric transport modelling, this concept does not strongly rely on the good colocation between the tracer and pollutant sources and can be used to monitor multiple sources within a single site, unlike the classical tracer release technique. The statistical inversion framework and the use of the tracer data for the configuration of the transport and inversion modelling systems should ensure that the transport modelling errors are correctly handled in the source estimation. The potential of this new concept is evaluated with a relatively simple practical implementation based on a Gaussian plume model and a series of inversions of controlled methane point sources using acetylene as a tracer gas. The experimental conditions are chosen so that they are suitable for the use of a Gaussian plume model to simulate the atmospheric transport. In these experiments, different configurations of methane and acetylene point source locations are tested to assess the efficiency of the method in comparison to the classic tracer release technique in coping with the distances between the different methane and acetylene sources. The results from these controlled experiments demonstrate that, when the targeted and tracer gases are not well collocated, this new approach provides a better estimate of the emission rates than the tracer release technique. As an example, the relative error between the estimated and actual emission rates is reduced from 32 % with the tracer release technique to 16 % with the combined approach in the case of a tracer located 60 m upwind of a single methane source. Further studies and more complex implementations with more advanced transport models and more advanced optimisations of their configuration will be required to generalise the applicability of the approach and strengthen its robustness.
Sources and remediation techniques for mercury contaminated soil.

PubMed

Xu, Jingying; Bravo, Andrea Garcia; Lagerkvist, Anders; Bertilsson, Stefan; Sjöblom, Rolf; Kumpiene, Jurate

2015-01-01

Mercury (Hg) in soils has increased by a factor of 3 to 10 in recent times mainly due to combustion of fossil fuels combined with long-range atmospheric transport processes. Other sources as chlor-alkali plants, gold mining and cement production can also be significant, at least locally. This paper summarizes the natural and anthropogenic sources that have contributed to the increase of Hg concentration in soil and reviews major remediation techniques and their applications to control soil Hg contamination. The focus is on soil washing, stabilisation/solidification, thermal treatment and biological techniques; but also the factors that influence Hg mobilisation in soil and therefore are crucial for evaluating and optimizing remediation techniques are discussed. Further research on bioremediation is encouraged and future study should focus on the implementation of different remediation techniques under field conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.
Active sources in the cutoff of centrifugal fans to reduce the blade tones at higher-order duct mode frequencies

NASA Astrophysics Data System (ADS)

Neise, W.; Koopmann, G. H.

1991-01-01

A previously developed (e.g., Neise and Koopmann, 1984; Koopmann et al., 1988) active noise control technique in which the unwanted acoustic signals from centrifugal fans are suppressed by placing two externally driven sources near the cutoff of the casing was applied to the frequency region where not only plane sound waves are propagational in the fan ducts but also higher-order acoustic modes. Using a specially designed fan noise testing facility, the performance of two fans (280-mm impeller diam and 508 mm diam) was monitored with static pressure taps mounted peripherally around the inlet nozzle. Experimental results show that the aerodynamically generated source pressure field around the cutoff is too complex to be successfully counterimaged by only two active sources introduced in this region. It is suggested that, for an efficient application of this noise control technique in the higher-order mode frequency regime, it is neccessary to use an active source involving larger number of individually driven loudspeakers.
Modeling and control of distributed energy systems during transition between grid connected and standalone modes

NASA Astrophysics Data System (ADS)

Arafat, Md Nayeem

Distributed generation systems (DGs) have been penetrating into our energy networks with the advancement in the renewable energy sources and energy storage elements. These systems can operate in synchronism with the utility grid referred to as the grid connected (GC) mode of operation, or work independently, referred to as the standalone (SA) mode of operation. There is a need to ensure continuous power flow during transition between GC and SA modes, referred to as the transition mode, in operating DGs. In this dissertation, efficient and effective transition control algorithms are developed for DGs operating either independently or collectively with other units. Three techniques are proposed in this dissertation to manage the proper transition operations. In the first technique, a new control algorithm is proposed for an independent DG which can operate in SA and GC modes. The proposed transition control algorithm ensures low total harmonic distortion (THD) and less voltage fluctuation during mode transitions compared to the other techniques. In the second technique, a transition control is suggested for a collective of DGs operating in a microgrid system architecture to improve the reliability of the system, reduce the cost, and provide better performance. In this technique, one of the DGs in a microgrid system, referred to as a dispatch unit , takes the additional responsibility of mode transitioning to ensure smooth transition and supply/demand balance in the microgrid. In the third technique, an alternative transition technique is proposed through hybridizing the current and droop controllers. The proposed hybrid transition control technique has higher reliability compared to the dispatch unit concept. During the GC mode, the proposed hybrid controller uses current control. During the SA mode, the hybrid controller uses droop control. During the transition mode, both of the controllers participate in formulating the inverter output voltage but with different weights or coefficients. Voltage source inverters interfacing the DGs as well as the proposed transition control algorithms have been modeled to analyze the stability of the algorithms in different configurations. The performances of the proposed algorithms are verified through simulation and experimental studies. It has been found that the proposed control techniques can provide smooth power flow to the local loads during the GC, SA and transition modes.
[Strategy Discussion for Pollution Control of Post-Consumer Home Medical Equipment].

PubMed

Zhang, Xu; Xu, Honglei; Huang, Yanhong; Peng, Xiaolong

2015-09-01

Compared with the recycle of post-consumer medical equipments in medical institutions, the treatment of post-consumer home medical equipments (HME) should be consummated in the field of academic research, policy and regulatory plus corresponding supporting industries. The HME industry situation and its classification, main components and properties are reviewed in this paper. The merits and demerits of various pollution control techniques in the recycle of post-consumer medical equipments are analysed. For instance, the source control techniques to improve the property of raw materials, the end treatment technique to recycle the HME and regenerate energy are also discussed. Further, the development prospect of pollution control technique in the recycle of HME and the challenges must face up to are also probed.
Remote Sensing and Monitoring of Earthen Flood-Control Structures

DTIC Science & Technology

2017-07-01

The source of energy in passive techniques is derived from incident solar radiation or sunlight that reacts with the atmosphere, hydrosphere, and...the energy reflected or emitted from the earth’s surface. The source of energy in passive techniques involves incident solar radiation or sunlight... solar radiation is reflected back into the atmosphere, or where heat energy is emitted from the earth’s surface. As shown by Figure 2-3, certain regions
Sensorimotor System Measurement Techniques

PubMed Central

Riemann, Bryan L.; Myers, Joseph B.; Lephart, Scott M.

2002-01-01

Objective: To provide an overview of currently available sensorimotor assessment techniques. Data Sources: We drew information from an extensive review of the scientific literature conducted in the areas of proprioception, neuromuscular control, and motor control measurement. Literature searches were conducted using MEDLINE for the years 1965 to 1999 with the key words proprioception, somatosensory evoked potentials, nerve conduction testing, electromyography, muscle dynamometry, isometric, isokinetic, kinetic, kinematic, posture, equilibrium, balance, stiffness, neuromuscular, sensorimotor, and measurement. Additional sources were collected using the reference lists of identified articles. Data Synthesis: Sensorimotor measurement techniques are discussed with reference to the underlying physiologic mechanisms, influential factors and locations of the variable within the system, clinical research questions, limitations of the measurement technique, and directions for future research. Conclusions/Recommendations: The complex interactions and relationships among the individual components of the sensorimotor system make measuring and analyzing specific characteristics and functions difficult. Additionally, the specific assessment techniques used to measure a variable can influence attained results. Optimizing the application of sensorimotor research to clinical settings can, therefore, be best accomplished through the use of common nomenclature to describe underlying physiologic mechanisms and specific measurement techniques. PMID:16558672
RACT (Reasonably Available Control Technology) determination for five industry categories in Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawks, R.L.; Schlesser, S.P.; Loudin, D.L.

Section 172(b)(2) of the Clean Air Act as amended August 1977, requires that SIP revisions 'provide for the implementation of all reasonably available control measures as expeditiously as practicable.' The use of RACT for stationary sources is defined as the lowest emission limit that a particular source is capable of meeting by the application of control technology that is reasonably available considering technological and economic feasibility. The purpose of this report has been to identify control techniques that best represent RACT for particular emission sources in TSP nonattainment areas in the State of Florida. These sources include phosphate process operations;more » portland cement plants; electric arc furnaces; sweat or pot furnaces; materials handling, sizing, screening, crushing, and grinding operations.« less
75 FR 60013 - Approval and Promulgation of Air Quality Implementation Plans; Maryland; Control of Volatile...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-29

... Promulgation of Air Quality Implementation Plans; Maryland; Control of Volatile Organic Compounds Emissions... Maryland's Volatile Organic Compounds from Specific Processes Regulation. Maryland has adopted standards... (RACT) requirements for sources of volatile organic compounds (VOCs) covered by control techniques...
The Hubble Space Telescope Servicing Mission 3A Contamination Control Program

NASA Technical Reports Server (NTRS)

Hansen, Patricia A.

2000-01-01

After nearly 10 years on-orbit, the Hubble Space Telescope (HST) external thermal control materials and paint have degraded due to exposure to the low Earth orbit environment. This presented a potentially large on-orbit contamination source (particles and/or debris). Contamination mitigation techniques were developed to augment existing on-orbit servicing contamination controls. They encompassed mission management, crew training, and crew aids and tools. These techniques were successfully employed during the HST Servicing Mission 3A, December 1999.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zohar, S.; Sterbinsky, G. E.

Here, we propose an experimental technique for extending feedback compensation of dissipative radiation used in nuclear magnetic resonance (NMR) to encompass ferromagnetic resonance (FMR). This method uses a balanced microwave power detector whose output is phase shifted π/2, amplified, and fed back to drive precession. Using classical control theory, we predict an electronically controllable narrowing of field swept FMR line-widths. This technique is predicted to compensate other sources of spin dissipation in addition to radiative loss.
Vision Based Autonomous Robotic Control for Advanced Inspection and Repair

NASA Technical Reports Server (NTRS)

Wehner, Walter S.

2014-01-01

The advanced inspection system is an autonomous control and analysis system that improves the inspection and remediation operations for ground and surface systems. It uses optical imaging technology with intelligent computer vision algorithms to analyze physical features of the real-world environment to make decisions and learn from experience. The advanced inspection system plans to control a robotic manipulator arm, an unmanned ground vehicle and cameras remotely, automatically and autonomously. There are many computer vision, image processing and machine learning techniques available as open source for using vision as a sensory feedback in decision-making and autonomous robotic movement. My responsibilities for the advanced inspection system are to create a software architecture that integrates and provides a framework for all the different subsystem components; identify open-source algorithms and techniques; and integrate robot hardware.
Environmental Technology Verification, Baghouse Filtration Products TTG Inc., TG800 Filtration Media (Tested August 2012)

EPA Science Inventory

Baghouses are air pollution control devices used to control particulate emissions from stationary sources and are among the technologies evaluated by the APCT Center. Baghouses and their accompanying filter media have long been one of the leading particulate control techniques fo...
Donaldson Company, Inc., Dura-Life #0701607 Filtration Media(Tested October 2011) (ETV Baghouse Filtration Products) Verification Report

EPA Science Inventory

Baghouses are air pollution control devices used to control particulate emissions from stationary sources and are among the technologies evaluated by the APCT Center. Baghouses and their accompanying filter media have long been one of the leading particulate control techniques fo...
Environmental Technology Verification; Baghouse Filtration Products TTG Inc., TG100 Filtration Media (Tested August 2012)

EPA Science Inventory

Baghouses are air pollution control devices used to control particulate emissions from stationary sources and are among the technologies evaluated by the APCT Center. Baghouses and their accompanying filter media have long been one of the leading particulate control techniques fo...
Design and Simulation of Control Technique for Permanent Magnet Synchronous Motor Using Space Vector Pulse Width Modulation

NASA Astrophysics Data System (ADS)

Khan, Mansoor; Yong, Wang; Mustafa, Ehtasham

2017-07-01

After the rapid advancement in the field of power electronics devices and drives for last few decades, there are different kinds of Pulse Width Modulation techniques which have been brought to the market. The applications ranging from industrial appliances to military equipment including the home appliances. The vey common application for the PWM is three phase voltage source inverter, which is used to convert DC to AC in the homes to supply the power to the house in case electricity failure, usually named as Un-interrupted Power Supply. In this paper Space Vector Pulse Width Modulation techniques is discussed and analysed under the control technique named as Field Oriented Control. The working and implementation of this technique has been studied by implementing on the three phase bridge inverter. The technique is used to control the Permanente Magnet Synchronous Motor. The drive system is successfully implemented in MATLAB/Simulink using the mathematical equation and algorithm to achieve the satisfactory results. PI type of controller is used to tuned ers of the motothe parametr i.e. torque and current.
Programed asynchronous serial data interrogation in a two-computer system

NASA Technical Reports Server (NTRS)

Schneberger, N. A.

1975-01-01

Technique permits redundant computers, with one unit in control mode and one in MONITOR mode, to interrogate the same serial data source. Its use for program-controlled serial data transfer results in extremely simple hardware and software mechanization.
40 CFR 63.345 - Provisions for new and reconstructed sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... electroplating, or chromium anodizing); (viii) A description of the air pollution control technique to be used to... National Emission Standards for Chromium Emissions From Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks § 63.345 Provisions for new and reconstructed sources. (a) This section identifies...
40 CFR 63.345 - Provisions for new and reconstructed sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... electroplating, or chromium anodizing); (viii) A description of the air pollution control technique to be used to... National Emission Standards for Chromium Emissions From Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks § 63.345 Provisions for new and reconstructed sources. (a) This section identifies...
Recent Progress in the Remote Detection of Vapours and Gaseous Pollutants.

ERIC Educational Resources Information Center

Moffat, A. J.; And Others

Work has been continuing on the correlation spectrometry techniques described at previous remote sensing symposiums. Advances in the techniques are described which enable accurate quantitative measurements of diffused atmospheric gases to be made using controlled light sources, accurate quantitative measurements of gas clouds relative to…
Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

PubMed Central

Theriot, Jordan C.; Ryan, Matthew D.; French, Tracy A.; Pearson, Ryan M.; Miyake, Garret M.

2016-01-01

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism. PMID:27166728
The Fate of Trace Contaminants in a Crewed Spacecraft Cabin Environment

NASA Technical Reports Server (NTRS)

Perry, Jay L.; Kayatin, Matthew J.

2016-01-01

Trace chemical contaminants produced via equipment offgassing, human metabolic sources, and vehicle operations are removed from the cabin atmosphere by active contamination control equipment and incidental removal by other air quality control equipment. The fate of representative trace contaminants commonly observed in spacecraft cabin atmospheres is explored. Removal mechanisms are described and predictive mass balance techniques are reviewed. Results from the predictive techniques are compared to cabin air quality analysis results. Considerations are discussed for an integrated trace contaminant control architecture suitable for long duration crewed space exploration missions.
Lights and Larvae

ERIC Educational Resources Information Center

TItlow, Josh; Anderson, Heidi; Cooper, Robin

2014-01-01

Switching genes between organisms and controlling an animal's brain using lasers may seem like science fiction, but with advancements in a technique called optogenetics, such experiments are now common in neuroscience research. Optogenetics combines recombinant DNA technology with a controlled light source to help researchers address…
Active Control of Inlet Noise on the JT15D Turbofan Engine

NASA Technical Reports Server (NTRS)

Smith, Jerome P.; Hutcheson, Florence V.; Burdisso, Ricardo A.; Fuller, Chris R.

1999-01-01

This report presents the key results obtained by the Vibration and Acoustics Laboratories at Virginia Tech over the year from November 1997 to December 1998 on the Active Noise Control of Turbofan Engines research project funded by NASA Langley Research Center. The concept of implementing active noise control techniques with fuselage-mounted error sensors is investigated both analytically and experimentally. The analytical part of the project involves the continued development of an advanced modeling technique to provide prediction and design guidelines for application of active noise control techniques to large, realistic high bypass engines of the type on which active control methods are expected to be applied. Results from the advanced analytical model are presented that show the effectiveness of the control strategies, and the analytical results presented for fuselage error sensors show good agreement with the experimentally observed results and provide additional insight into the control phenomena. Additional analytical results are presented for active noise control used in conjunction with a wavenumber sensing technique. The experimental work is carried out on a running JT15D turbofan jet engine in a test stand at Virginia Tech. The control strategy used in these tests was the feedforward Filtered-X LMS algorithm. The control inputs were supplied by single and multiple circumferential arrays of acoustic sources equipped with neodymium iron cobalt magnets mounted upstream of the fan. The reference signal was obtained from an inlet mounted eddy current probe. The error signals were obtained from a number of pressure transducers flush-mounted in a simulated fuselage section mounted in the engine test cell. The active control methods are investigated when implemented with the control sources embedded within the acoustically absorptive material on a passively-lined inlet. The experimental results show that the combination of active control techniques with fuselage-mounted error sensors and passive control techniques is an effective means of reducing radiated noise from turbofan engines. Strategic selection of the location of the error transducers is shown to be effective for reducing the radiation towards particular directions in the farfield. An analytical model is used to predict the behavior of the control system and to guide the experimental design configurations, and the analytical results presented show good agreement with the experimentally observed results.
78 FR 9648 - Approval and Promulgation of Air Quality Implementation Plans; District of Columbia; Volatile...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-11

... Regulations (DCMR) for the Control of Volatile Organic Compounds (VOC) to meet the requirement to adopt reasonably available control technology (RACT) for sources as recommended by the Ozone Transport Commission (OTC) model rules and EPA's Control Techniques Guidelines (CTG) standards. On January 26, 2010 and...
Contributions of Organic Sources to Atmospheric Aerosol Particle Concentrations and Growth

NASA Astrophysics Data System (ADS)

Russell, L. M.

2017-12-01

Organic molecules are important contributors to aerosol particle mass and number concentrations through primary emissions as well as secondary growth in the atmosphere. New techniques for measuring organic aerosol components in atmospheric particles have improved measurements of this contribution in the last 20 years, including Scanning Transmission X-ray Microscopy Near Edge X-ray Absorption Fine Structure (STXM-NEXAFS), Fourier Transform Infrared spectroscopy (FTIR), and High-Resolution Aerosol Mass Spectrometry (AMS). STXM-NEXAFS individual aerosol particle composition illustrated the variety of morphology of organic components in marine aerosols, the inherent relationships between organic composition and shape, and the links between atmospheric aerosol composition and particles produced in smog chambers. This type of single particle microscopy has also added to size distribution measurements by providing evidence of how surface-controlled and bulk-controlled processes contribute to the growth of particles in the atmosphere. FTIR analysis of organic functional groups are sufficient to distinguish combustion, marine, and terrestrial organic particle sources and to show that each of those types of sources has a surprisingly similar organic functional group composition over four different oceans and four different continents. Augmenting the limited sampling of these off-line techniques with side-by-side inter-comparisons to online AMS provides complementary composition information and consistent quantitative attribution to sources (despite some clear method differences). Single-particle AMS techniques using light scattering and event trigger modes have now also characterized the types of particles found in urban, marine, and ship emission aerosols. Most recently, by combining with off-line techniques, single particle composition measurements have separated and quantified the contributions of organic, sulfate and salt components from ocean biogenic and sea spray emissions to particles, addressing the persistent question of the sources of cloud condensation nuclei in clean marine conditions.
Diagnostic techniques for measurement of aerodynamic noise in free field and reverberant environment of wind tunnels

NASA Technical Reports Server (NTRS)

El-Sum, H. M. A.; Mawardi, O. K.

1973-01-01

Techniques for studying aerodynamic noise generating mechanisms without disturbing the flow in a free field, and in the reverberation environment of the ARC wind tunnel were investigated along with the design and testing of an acoustic antenna with an electronic steering control. The acoustic characteristics of turbojet as a noise source, detection of direct sound from a source in a reverberant background, optical diagnostic methods, and the design characteristics of a high directivity acoustic antenna. Recommendations for further studies are included.
A novel low cost pulse excitation source to study trap spectroscopy of persistent luminescent materials

NASA Astrophysics Data System (ADS)

Chandrasekhar, Ngangbam; Singh, Nungleppam Monorajan; Gartia, R. K.

2018-04-01

Luminescent techniques require one or the other source of excitations which may vary from high cost X-rays, γ-rays, β-rays etc. to low cost LED. Persistent luminescent materials or Glow-in-the-Dark phosphors are the optical harvesters which store the optical energy from day light illuminating a whole night. They are so sensitive that they can be excited even with the low light of firefly. Therefore, instead of using a high cost excitation source authors have developed a low cost functioning of excitation source controlling short pulses of LED to excite persistent phosphors with the aid of ExpEYES Junior (Hardware/software framework developed by IUAC, New Delhi). Using this, the authors have excited the sample under investigation upto 10 ms. Trap spectroscopy of the pre-excited sample with LED is studied using Thermoluminescence (TL) technique. In this communication, development of the excitation source is discussed and demonstrate the its usefulness in the study of trap spectroscopy of commercially available CaS:Eu2+, Sm3+. Trapping parameters are also evaluated using Computerized Glow Curve Deconvolution (CGCD) technique.
Refinement and application of acoustic impulse technique to study nozzle transmission characteristics

NASA Technical Reports Server (NTRS)

Salikuddin, M.; Brown, W. H.; Ramakrishnan, R.; Tanna, H. K.

1983-01-01

An improved acoustic impulse technique was developed and was used to study the transmission characteristics of duct/nozzle systems. To accomplish the above objective, various problems associated with the existing spark-discharge impulse technique were first studied. These included (1) the nonlinear behavior of high intensity pulses, (2) the contamination of the signal with flow noise, (3) low signal-to-noise ratio at high exhaust velocities, and (4) the inability to control or shape the signal generated by the source, specially when multiple spark points were used as the source. The first step to resolve these problems was the replacement of the spark-discharge source with electroacoustic driver(s). These included (1) synthesizing on acoustic impulse with acoustic driver(s) to control and shape the output signal, (2) time domain signal averaging to remove flow noise from the contaminated signal, (3) signal editing to remove unwanted portions of the time history, (4) spectral averaging, and (5) numerical smoothing. The acoustic power measurement technique was improved by taking multiple induct measurements and by a modal decomposition process to account for the contribution of higher order modes in the power computation. The improved acoustic impulse technique was then validated by comparing the results derived by an impedance tube method. The mechanism of acoustic power loss, that occurs when sound is transmitted through nozzle terminations, was investigated. Finally, the refined impulse technique was applied to obtain more accurate results for the acoustic transmission characteristics of a conical nozzle and a multi-lobe multi-tube supressor nozzle.
40 CFR 63.1420 - Applicability and designation of affected sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... control technique. (iii) Group determinations. For emission points where the owner or operator is required... source is defined as the group of one or more polyether polyol manufacturing process units (PMPUs) and...), the group of one or more PMPUs and associated equipment, as listed in paragraph (a)(4) of this section...

40 CFR 63.1420 - Applicability and designation of affected sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... control technique. (iii) Group determinations. For emission points where the owner or operator is required... source is defined as the group of one or more polyether polyol manufacturing process units (PMPUs) and...), the group of one or more PMPUs and associated equipment, as listed in paragraph (a)(4) of this section...
Effect of mercury and arsenic from industrial effluents on the drinking water and comparison of the water quality of polluted and non-polluted areas: a case study of Peshawar and Lower Dir.

PubMed

Ishaq, M; Jan, F Akbar; Khan, Murad Ali; Ihsanullah, I; Ahmad, I; Shakirullah, M; Roohullah

2013-02-01

The purpose of the present study was to find out the sources of mercury and arsenic pollution of water in the industrial area of Peshawar, the capital of Khyber Pakhtunkhwa, Pakistan. Samples of effluents, mud, and water were collected from the target area (industrial area of Peshawar), the area of water supply source, and from the less polluted area, the Lower Dir district, as the control. Hg was determined by the cold vapor generation technique, while arsenic was determined using the electrothermal atomic absorption technique. Data of the water from the industrial area were compared with that of the source area, control area, as well as with the WHO and some international drinking water quality standards. The results show that some parameters, i.e., TDS, DO, pH, and hardness, were more than the permissible limits. Textile and glass industries were found to be the major sources of Hg and As pollution. Downstream dilution of these contaminants was also observed.
Measurement Techniques for Transmit Source Clock Jitter for Weak Serial RF Links

NASA Technical Reports Server (NTRS)

Lansdowne, Chatwin A.; Schlesinger, Adam M.

2010-01-01

Techniques for filtering clock jitter measurements are developed, in the context of controlling data modulation jitter on an RF carrier to accommodate low signal-to-noise ratio thresholds of high-performance error correction codes. Measurement artifacts from sampling are considered, and a tutorial on interpretation of direct readings is included.
Enhancing Self-Efficacy and Performance: An Experimental Comparison of Psychological Techniques

ERIC Educational Resources Information Center

Wright, Bradley James; O'Halloran, Paul Daniel; Stukas, Arthur Anthony

2016-01-01

Purpose: We assessed how 6 psychological performance enhancement techniques (PETs) differentially improved self-efficacy (SE) and skill performance. We also assessed whether vicarious experiences and verbal persuasion as posited sources of SE (Bandura, 1982) were supported and, further, if the effects of the 6 PETs remained after controlling for…
40 CFR 52.126 - Control strategy and regulations: Particulate matter.

Code of Federal Regulations, 2010 CFR

2010-07-01

... be determined by using method 2 and traversing according to method 1. Gas analysis shall be performed using the integrated sample technique of method 3, and moisture content shall be determined by the condenser technique of method 4. (iii) All tests shall be conducted while the source is operating at the...
TEST QA PLAN FOR THE VERIFICATION TESTING OF BAGHOUSE FILTRATION PRODUCTS

EPA Science Inventory

Baghouses and their accompanying filter media are a leading particulate control technique for industrial sources. Increasingly emphasis on higher removal efficiencies has helped the baghouse to be even more competitive when compared to other control devices. At present there is n...
Disturbance Source Separation in Shear Flows Using Blind Source Separation Methods

NASA Astrophysics Data System (ADS)

Gluzman, Igal; Cohen, Jacob; Oshman, Yaakov

2017-11-01

A novel approach is presented for identifying disturbance sources in wall-bounded shear flows. The method can prove useful for active control of boundary layer transition from laminar to turbulent flow. The underlying idea is to consider the flow state, as measured in sensors, to be a mixture of sources, and to use Blind Source Separation (BSS) techniques to recover the separate sources and their unknown mixing process. We present a BSS method based on the Degenerate Unmixing Estimation Technique. This method can be used to identify any (a priori unknown) number of sources by using the data acquired by only two sensors. The power of the new method is demonstrated via numerical and experimental proofs of concept. Wind tunnel experiments involving boundary layer flow over a flat plate were carried out, in which two hot-wire anemometers were used to separate disturbances generated by disturbance generators such as a single dielectric barrier discharge plasma actuator and a loudspeaker.
A technique for phase correction in Fourier transform spectroscopy

NASA Astrophysics Data System (ADS)

Artsang, P.; Pongchalee, P.; Palawong, K.; Buisset, C.; Meemon, P.

2018-03-01

Fourier transform spectroscopy (FTS) is a type of spectroscopy that can be used to analyze components in the sample. The basic setup that is commonly used in this technique is "Michelson interferometer". The interference signal obtained from interferometer can be Fourier transformed into the spectral pattern of the illuminating light source. To experimentally study the concept of the Fourier transform spectroscopy, the project started by setup the Michelson interferometer in the laboratory. The implemented system used a broadband light source in near infrared region (0.81-0.89 μm) and controlled the movable mirror by using computer controlled motorized translation stage. In the early study, there is no sample the interference path. Therefore, the theoretical spectral results after the Fourier transformation of the captured interferogram must be the spectral shape of the light source. One main challenge of the FTS is to retrieve the correct phase information of the inferferogram that relates with the correct spectral shape of the light source. One main source of the phase distortion in FTS that we observed from our system is the non-linear movement of the movable reference mirror of the Michelson interferometer. Therefore, to improve the result, we coupled a monochromatic light source to the implemented interferometer. We simultaneously measured the interferograms of the monochromatic and broadband light sources. The interferogram of the monochromatic light source was used to correct the phase of the interferogram of the broadband light source. The result shows significant improvement in the computed spectral shape.
Determination of Phenols and Trimethylamine in Industrial Effluents

NASA Technical Reports Server (NTRS)

Levaggi, D. A.; Feldstein, M.

1971-01-01

For regulatory purposes to control certain odorous compounds the analysis of phenols and trimethylamines in industrial effluents is necessary. The Bay Area Air Pollution Control District laboratory has been determining these gases by gas chromatographic techniques. The procedures for sample collection, preparation for analysis and determination are described in detail. Typical data from various sources showing the effect of proposed regulations is shown. Extensive sampling and usage of these procedures has shown them to be accurate, reliable and suitable to all types of source effluents.
Investigation of laser dynamics, modulation and control by means of intra-cavity time varying perturbation

NASA Technical Reports Server (NTRS)

Harris, S. E.; Siegman, A. E.; Kuizenga, D. J.; Kung, A. H.; Young, J. F.; Bekkers, G. W.; Bloom, D. M.; Newton, J. H.; Phillion, D. W.

1975-01-01

The generation of tunable visible, infrared, and ultraviolet light is examined, along with the control of this light by means of novel mode-locking and modulation techniques. Transient mode-locking of the Nd:YAG laser and generation of short tunable pulses in the visible and the alkali metal inert gas excimer laser systems were investigated. Techniques for frequency conversion of high power and high energy laser radiation are discussed, along with high average power blue and UV laser light sources.
A proposed method for electronic feedback compensation of damping in ferromagnetic resonance

DOE PAGES

Zohar, S.; Sterbinsky, G. E.

2017-07-10

Here, we propose an experimental technique for extending feedback compensation of dissipative radiation used in nuclear magnetic resonance (NMR) to encompass ferromagnetic resonance (FMR). This method uses a balanced microwave power detector whose output is phase shifted π/2, amplified, and fed back to drive precession. Using classical control theory, we predict an electronically controllable narrowing of field swept FMR line-widths. This technique is predicted to compensate other sources of spin dissipation in addition to radiative loss.
A proposed method for electronic feedback compensation of damping in ferromagnetic resonance

NASA Astrophysics Data System (ADS)

Zohar, S.; Sterbinsky, G. E.

2017-12-01

We propose an experimental technique for extending feedback compensation of dissipative radiation used in nuclear magnetic resonance (NMR) to encompass ferromagnetic resonance (FMR). This method uses a balanced microwave power detector whose output is phase shifted π / 2 , amplified, and fed back to drive precession. Using classical control theory, we predict an electronically controllable narrowing of field swept FMR line-widths. This technique is predicted to compensate other sources of spin dissipation in addition to radiative loss.
Environmental Technology Verification Report and Statement for Baghouse Filtration Products, W. L. Gore & Associates, Inc. 5117 High Durability PPS Laminate Filtration Media (Tested March-April 2012)

EPA Science Inventory

Baghouses are air pollution control devices used to control particulate emissions from stationary sources and are among the technologies evaluated by the APCT Center. Baghouses and their accompanying filter media have long been one of the leading particulate control techniques fo...
How to Integrate Variable Power Source into a Power Grid

NASA Astrophysics Data System (ADS)

Asano, Hiroshi

This paper discusses how to integrate variable power source such as wind power and photovoltaic generation into a power grid. The intermittent renewable generation is expected to penetrate for less carbon intensive power supply system, but it causes voltage control problem in the distribution system, and supply-demand imbalance problem in a whole power system. Cooperative control of customers' energy storage equipment such as water heater with storage tank for reducing inverse power flow from the roof-top PV system, the operation technique using a battery system and the solar radiation forecast for stabilizing output of variable generation, smart charging of plug-in hybrid electric vehicles for load frequency control (LFC), and other methods to integrate variable power source with improving social benefits are surveyed.
Multidimensional optimal droop control for wind resources in DC microgrids

NASA Astrophysics Data System (ADS)

Bunker, Kaitlyn J.

Two important and upcoming technologies, microgrids and electricity generation from wind resources, are increasingly being combined. Various control strategies can be implemented, and droop control provides a simple option without requiring communication between microgrid components. Eliminating the single source of potential failure around the communication system is especially important in remote, islanded microgrids, which are considered in this work. However, traditional droop control does not allow the microgrid to utilize much of the power available from the wind. This dissertation presents a novel droop control strategy, which implements a droop surface in higher dimension than the traditional strategy. The droop control relationship then depends on two variables: the dc microgrid bus voltage, and the wind speed at the current time. An approach for optimizing this droop control surface in order to meet a given objective, for example utilizing all of the power available from a wind resource, is proposed and demonstrated. Various cases are used to test the proposed optimal high dimension droop control method, and demonstrate its function. First, the use of linear multidimensional droop control without optimization is demonstrated through simulation. Next, an optimal high dimension droop control surface is implemented with a simple dc microgrid containing two sources and one load. Various cases for changing load and wind speed are investigated using simulation and hardware-in-the-loop techniques. Optimal multidimensional droop control is demonstrated with a wind resource in a full dc microgrid example, containing an energy storage device as well as multiple sources and loads. Finally, the optimal high dimension droop control method is applied with a solar resource, and using a load model developed for a military patrol base application. The operation of the proposed control is again investigated using simulation and hardware-in-the-loop techniques.
76 FR 4578 - Approval and Promulgation of Air Quality Implementation Plans; Maryland; Adoption of Control...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-26

... Wood Paneling Coatings AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY... (RACT) for sources covered by EPA's Control Techniques Guidelines (CTG) for flat wood paneling coatings. These amendments will reduce emissions of volatile organic compound (VOC) from flat wood coating...
76 FR 13567 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Adoption of Control...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-14

... Flat Wood Paneling Surface Coating Processes AGENCY: Environmental Protection Agency (EPA). ACTION... sources covered by EPA's Control Techniques Guidelines (CTG) standards for flat wood paneling surface... Protection (PADEP) submitted to EPA a SIP revision concerning the adoption of the CTG for flat wood paneling...
Translation of an Object Using Phase-Controlled Sound Sources in Acoustic Levitation

NASA Astrophysics Data System (ADS)

Matsui, Takayasu; Ohdaira, Etsuzo; Masuzawa, Nobuyoshi; Ide, Masao

1995-05-01

Acoustic levitation is used for positioning materials in the development of new materials in space where there is no gravity. This technique is applicable to materials for which electromagnetic force cannot be used. If the levitation point of the materials can be controlled freely in this application, possibilities of new applications will be extended. In this paper we report on an experimental study on controlling the levitation point of the object in an acoustic levitation system. The system fabricated and tested in this study has two sound sources with vibrating plates facing each other. Translation of the object can be achieved by controlling the phase of the energizing electrical signal for one of the sound sources. It was found that the levitation point can be moved smoothly in proportion to the phase difference between the vibrating plates.
Fuzzy Logic Controlled Solar Module for Driving Three- Phase Induction Motor

NASA Astrophysics Data System (ADS)

Afiqah Zainal, Nurul; Sooi Tat, Chan; Ajisman

2016-02-01

Renewable energy produced by solar module gives advantages for generated three- phase induction motor in remote area. But, solar module's ou tput is uncertain and complex. Fuzzy logic controller is one of controllers that can handle non-linear system and maximum power of solar module. Fuzzy logic controller used for Maximum Power Point Tracking (MPPT) technique to control Pulse-Width Modulation (PWM) for switching power electronics circuit. DC-DC boost converter used to boost up photovoltaic voltage to desired output and supply voltage source inverter which controlled by three-phase PWM generated by microcontroller. IGBT switched Voltage source inverter (VSI) produced alternating current (AC) voltage from direct current (DC) source to control speed of three-phase induction motor from boost converter output. Results showed that, the output power of solar module is optimized and controlled by using fuzzy logic controller. Besides that, the three-phase induction motor can be drive and control using VSI switching by the PWM signal generated by the fuzzy logic controller. This concluded that the non-linear system can be controlled and used in driving three-phase induction motor.
Investigation of the cross-ship comparison monitoring method of failure detection in the HIMAT RPRV. [digital control techniques using airborne microprocessors

NASA Technical Reports Server (NTRS)

Wolf, J. A.

1978-01-01

The Highly maneuverable aircraft technology (HIMAT) remotely piloted research vehicle (RPRV) uses cross-ship comparison monitoring of the actuator RAM positions to detect a failure in the aileron, canard, and elevator control surface servosystems. Some possible sources of nuisance trips for this failure detection technique are analyzed. A FORTRAN model of the simplex servosystems and the failure detection technique were utilized to provide a convenient means of changing parameters and introducing system noise. The sensitivity of the technique to differences between servosystems and operating conditions was determined. The cross-ship comparison monitoring method presently appears to be marginal in its capability to detect an actual failure and to withstand nuisance trips.

Bipolar square-wave current source for transient electromagnetic systems based on constant shutdown time

NASA Astrophysics Data System (ADS)

Wang, Shilong; Yin, Changchun; Lin, Jun; Yang, Yu; Hu, Xueyan

2016-03-01

Cooperative work of multiple magnetic transmitting sources is a new trend in the development of transient electromagnetic system. The key is the bipolar current waves shutdown, concurrently in the inductive load. In the past, it was difficult to use the constant clamping voltage technique to realize the synchronized shutdown of currents with different peak values. Based on clamping voltage technique, we introduce a new controlling method with constant shutdown time. We use the rising time to control shutdown time and use low voltage power source to control peak current. From the viewpoint of the circuit energy loss, by taking the high-voltage capacitor bypass resistance and the capacitor of the passive snubber circuit into account, we establish the relationship between the rising time and the shutdown time. Since the switch is not ideal, we propose a new method to test the shutdown time by the low voltage, the high voltage and the peak current. Experimental results show that adjustment of the current rising time can precisely control the value of the clamp voltage. When the rising time is fixed, the shutdown time is unchanged. The error for shutdown time deduced from the energy consumption is less than 6%. The new controlling method on current shutdown proposed in this paper can be used in the cooperative work of borehole and ground transmitting system.
Bipolar square-wave current source for transient electromagnetic systems based on constant shutdown time.

PubMed

Wang, Shilong; Yin, Changchun; Lin, Jun; Yang, Yu; Hu, Xueyan

2016-03-01

Cooperative work of multiple magnetic transmitting sources is a new trend in the development of transient electromagnetic system. The key is the bipolar current waves shutdown, concurrently in the inductive load. In the past, it was difficult to use the constant clamping voltage technique to realize the synchronized shutdown of currents with different peak values. Based on clamping voltage technique, we introduce a new controlling method with constant shutdown time. We use the rising time to control shutdown time and use low voltage power source to control peak current. From the viewpoint of the circuit energy loss, by taking the high-voltage capacitor bypass resistance and the capacitor of the passive snubber circuit into account, we establish the relationship between the rising time and the shutdown time. Since the switch is not ideal, we propose a new method to test the shutdown time by the low voltage, the high voltage and the peak current. Experimental results show that adjustment of the current rising time can precisely control the value of the clamp voltage. When the rising time is fixed, the shutdown time is unchanged. The error for shutdown time deduced from the energy consumption is less than 6%. The new controlling method on current shutdown proposed in this paper can be used in the cooperative work of borehole and ground transmitting system.
Photochemical grid model implementation and application of ...

EPA Pesticide Factsheets

For the purposes of developing optimal emissions control strategies, efficient approaches are needed to identify the major sources or groups of sources that contribute to elevated ozone (O3) concentrations. Source-based apportionment techniques implemented in photochemical grid models track sources through the physical and chemical processes important to the formation and transport of air pollutants. Photochemical model source apportionment has been used to track source impacts of specific sources, groups of sources (sectors), sources in specific geographic areas, and stratospheric and lateral boundary inflow on O3. The implementation and application of a source apportionment technique for O3 and its precursors, nitrogen oxides (NOx) and volatile organic compounds (VOCs), for the Community Multiscale Air Quality (CMAQ) model are described here. The Integrated Source Apportionment Method (ISAM) O3 approach is a hybrid of source apportionment and source sensitivity in that O3 production is attributed to precursor sources based on O3 formation regime (e.g., for a NOx-sensitive regime, O3 is apportioned to participating NOx emissions). This implementation is illustrated by tracking multiple emissions source sectors and lateral boundary inflow. NOx, VOC, and O3 attribution to tracked sectors in the application are consistent with spatial and temporal patterns of precursor emissions. The O3 ISAM implementation is further evaluated through comparisons of apportioned am
Support Center for Regulatory Atmospheric Modeling (SCRAM)

EPA Pesticide Factsheets

This technical site provides access to air quality models (including computer code, input data, and model processors) and other mathematical simulation techniques used in assessing air emissions control strategies and source impacts.
Improved techniques for thermomechanical testing in support of deformation modeling

NASA Technical Reports Server (NTRS)

Castelli, Michael G.; Ellis, John R.

1992-01-01

The feasibility of generating precise thermomechanical deformation data to support constitutive model development was investigated. Here, the requirement is for experimental data that is free from anomalies caused by less than ideal equipment and procedures. A series of exploratory tests conducted on Hastelloy X showed that generally accepted techniques for strain controlled tests were lacking in at least three areas. Specifically, problems were encountered with specimen stability, thermal strain compensation, and temperature/mechanical strain phasing. The source of these difficulties was identified and improved thermomechanical testing techniques to correct them were developed. These goals were achieved by developing improved procedures for measuring and controlling thermal gradients and by designing a specimen specifically for thermomechanical testing. In addition, innovative control strategies were developed to correctly proportion and phase the thermal and mechanical components of strain. Subsequently, the improved techniques were used to generate deformation data for Hastelloy X over the temperature range, 200 to 1000 C.
Urban Runoff: National Management Measures

EPA Pesticide Factsheets

This helps citizens and municipalities in urban areas protect bodies of water from polluted runoff . These scientifically sound techniques are the best practices known today. The guidance helps states to implement their nonpoint source control program.
Improved Pseudo-section Representation for CSAMT Data in Geothermal Exploration

NASA Astrophysics Data System (ADS)

Grandis, Hendra; Sumintadireja, Prihadi

2017-04-01

Controlled-Source Audio-frequency Magnetotellurics (CSAMT) is a frequency domain sounding technique employing typically a grounded electric dipole as the primary electromagnetic (EM) source to infer the subsurface resistivity distribution. The use of an artificial source provides coherent signals with higher signal-to-noise ratio and overcomes the problems with randomness and fluctuation of the natural EM fields used in MT. However, being an extension of MT, the CSAMT data still uses apparent resistivity and phase for data representation. The finite transmitter-receiver distance in CSAMT leads to a somewhat “distorted” response of the subsurface compared to MT data. We propose a simple technique to present CSAMT data as an apparent resistivity pseudo-section with more meaningful information for qualitative interpretation. Tests with synthetic and field CSAMT data showed that the simple technique is valid only for sounding curves exhibiting a transition from high - low - high resistivity (i.e. H-type) prevailing in data from a geothermal prospect. For quantitative interpretation, we recommend the use of the full-solution of CSAMT modelling since our technique is not valid for more general cases.
Gas turbine engine active clearance control

NASA Technical Reports Server (NTRS)

Deveau, Paul J. (Inventor); Greenberg, Paul B. (Inventor); Paolillo, Roger E. (Inventor)

1985-01-01

Method for controlling the clearance between rotating and stationary components of a gas turbine engine are disclosed. Techniques for achieving close correspondence between the radial position of rotor blade tips and the circumscribing outer air seals are disclosed. In one embodiment turbine case temperature modifying air is provided in flow rate, pressure and temperature varied as a function of engine operating condition. The modifying air is scheduled from a modulating and mixing valve supplied with dual source compressor air. One source supplies relatively low pressure, low temperature air and the other source supplies relatively high pressure, high temperature air. After the air has been used for the active clearance control (cooling the high pressure turbine case) it is then used for cooling the structure that supports the outer air seal and other high pressure turbine component parts.
Error Sources in Asteroid Astrometry

NASA Technical Reports Server (NTRS)

Owen, William M., Jr.

2000-01-01

Asteroid astrometry, like any other scientific measurement process, is subject to both random and systematic errors, not all of which are under the observer's control. To design an astrometric observing program or to improve an existing one requires knowledge of the various sources of error, how different errors affect one's results, and how various errors may be minimized by careful observation or data reduction techniques.
Combining chemometric tools for assessing hazard sources and factors acting simultaneously in contaminated areas. Case study: "Mar Piccolo" Taranto (South Italy).

PubMed

Mali, Matilda; Dell'Anna, Maria Michela; Notarnicola, Michele; Damiani, Leonardo; Mastrorilli, Piero

2017-10-01

Almost all marine coastal ecosystems possess complex structural and dynamic characteristics, which are influenced by anthropogenic causes and natural processes as well. Revealing the impact of sources and factors controlling the spatial distributions of contaminants within highly polluted areas is a fundamental propaedeutic step of their quality evaluation. Combination of different pattern recognition techniques, applied to one of the most polluted Mediterranean coastal basin, resulted in a more reliable hazard assessment. PCA/CA and factorial ANOVA were exploited as complementary techniques for apprehending the impact of multi-sources and multi-factors acting simultaneously and leading to similarities or differences in the spatial contamination pattern. The combination of PCA/CA and factorial ANOVA allowed, on one hand to determine the main processes and factors controlling the contamination trend within different layers and different basins, and, on the other hand, to ascertain possible synergistic effects. This approach showed the significance of a spatially representative overview given by the combination of PCA-CA/ANOVA in inferring the historical anthropogenic sources loading on the area. Copyright © 2017 Elsevier Ltd. All rights reserved.
Efficient techniques for wave-based sound propagation in interactive applications

NASA Astrophysics Data System (ADS)

Mehra, Ravish

Sound propagation techniques model the effect of the environment on sound waves and predict their behavior from point of emission at the source to the final point of arrival at the listener. Sound is a pressure wave produced by mechanical vibration of a surface that propagates through a medium such as air or water, and the problem of sound propagation can be formulated mathematically as a second-order partial differential equation called the wave equation. Accurate techniques based on solving the wave equation, also called the wave-based techniques, are too expensive computationally and memory-wise. Therefore, these techniques face many challenges in terms of their applicability in interactive applications including sound propagation in large environments, time-varying source and listener directivity, and high simulation cost for mid-frequencies. In this dissertation, we propose a set of efficient wave-based sound propagation techniques that solve these three challenges and enable the use of wave-based sound propagation in interactive applications. Firstly, we propose a novel equivalent source technique for interactive wave-based sound propagation in large scenes spanning hundreds of meters. It is based on the equivalent source theory used for solving radiation and scattering problems in acoustics and electromagnetics. Instead of using a volumetric or surface-based approach, this technique takes an object-centric approach to sound propagation. The proposed equivalent source technique generates realistic acoustic effects and takes orders of magnitude less runtime memory compared to prior wave-based techniques. Secondly, we present an efficient framework for handling time-varying source and listener directivity for interactive wave-based sound propagation. The source directivity is represented as a linear combination of elementary spherical harmonic sources. This spherical harmonic-based representation of source directivity can support analytical, data-driven, rotating or time-varying directivity function at runtime. Unlike previous approaches, the listener directivity approach can be used to compute spatial audio (3D audio) for a moving, rotating listener at interactive rates. Lastly, we propose an efficient GPU-based time-domain solver for the wave equation that enables wave simulation up to the mid-frequency range in tens of minutes on a desktop computer. It is demonstrated that by carefully mapping all the components of the wave simulator to match the parallel processing capabilities of the graphics processors, significant improvement in performance can be achieved compared to the CPU-based simulators, while maintaining numerical accuracy. We validate these techniques with offline numerical simulations and measured data recorded in an outdoor scene. We present results of preliminary user evaluations conducted to study the impact of these techniques on user's immersion in virtual environment. We have integrated these techniques with the Half-Life 2 game engine, Oculus Rift head-mounted display, and Xbox game controller to enable users to experience high-quality acoustics effects and spatial audio in the virtual environment.
Impacts of Oil and Gas Production on Winter Ozone Pollution in the Uintah Basin Using Model Source Apportionment

NASA Astrophysics Data System (ADS)

Tran, H. N. Q.; Tran, T. T.; Mansfield, M. L.; Lyman, S. N.

2014-12-01

Contributions of emissions from oil and gas activities to elevated ozone concentrations in the Uintah Basin - Utah were evaluated using the CMAQ Integrated Source Apportionment Method (CMAQ-ISAM) technique, and were compared with the results of traditional budgeting methods. Unlike the traditional budgeting method, which compares simulations with and without emissions of the source(s) in question to quantify its impacts, the CMAQ-ISAM technique assigns tags to emissions of each source and tracks their evolution through physical and chemical processes to quantify the final ozone product yield from the source. Model simulations were performed for two episodes in winter 2013 of low and high ozone to provide better understanding of source contributions under different weather conditions. Due to the highly nonlinear ozone chemistry, results obtained from the two methods differed significantly. The growing oil and gas industry in the Uintah Basin is the largest contributor to the elevated zone (>75 ppb) observed in the Basin. This study therefore provides an insight into the impact of oil and gas industry on the ozone issue, and helps in determining effective control strategies.
Controlled in situ etch-back

NASA Technical Reports Server (NTRS)

Mattauch, R. J.; Seabaugh, A. C. (Inventor)

1981-01-01

A controlled in situ etch-back technique is disclosed in which an etch melt and a growth melt are first saturated by a source-seed crystal and thereafter etch-back of a substrate takes place by the slightly undersaturated etch melt, followed by LPE growth of a layer by the growth melt, which is slightly supersaturated.
Controlling Air Pollution; A Primer on Stationary Source Control Techniques.

ERIC Educational Resources Information Center

Corman, Rena

This companion document to "Air Pollution Primer" is written for the nonexpert in air pollution; however, it does assume a familiarity with air pollution problems. This work is oriented toward providing the reader with knowledge about current and proposed air quality legislation and knowledge about available technology to meet these standards for…
MEG source imaging method using fast L1 minimum-norm and its applications to signals with brain noise and human resting-state source amplitude images.

PubMed

Huang, Ming-Xiong; Huang, Charles W; Robb, Ashley; Angeles, AnneMarie; Nichols, Sharon L; Baker, Dewleen G; Song, Tao; Harrington, Deborah L; Theilmann, Rebecca J; Srinivasan, Ramesh; Heister, David; Diwakar, Mithun; Canive, Jose M; Edgar, J Christopher; Chen, Yu-Han; Ji, Zhengwei; Shen, Max; El-Gabalawy, Fady; Levy, Michael; McLay, Robert; Webb-Murphy, Jennifer; Liu, Thomas T; Drake, Angela; Lee, Roland R

2014-01-01

The present study developed a fast MEG source imaging technique based on Fast Vector-based Spatio-Temporal Analysis using a L1-minimum-norm (Fast-VESTAL) and then used the method to obtain the source amplitude images of resting-state magnetoencephalography (MEG) signals for different frequency bands. The Fast-VESTAL technique consists of two steps. First, L1-minimum-norm MEG source images were obtained for the dominant spatial modes of sensor-waveform covariance matrix. Next, accurate source time-courses with millisecond temporal resolution were obtained using an inverse operator constructed from the spatial source images of Step 1. Using simulations, Fast-VESTAL's performance was assessed for its 1) ability to localize multiple correlated sources; 2) ability to faithfully recover source time-courses; 3) robustness to different SNR conditions including SNR with negative dB levels; 4) capability to handle correlated brain noise; and 5) statistical maps of MEG source images. An objective pre-whitening method was also developed and integrated with Fast-VESTAL to remove correlated brain noise. Fast-VESTAL's performance was then examined in the analysis of human median-nerve MEG responses. The results demonstrated that this method easily distinguished sources in the entire somatosensory network. Next, Fast-VESTAL was applied to obtain the first whole-head MEG source-amplitude images from resting-state signals in 41 healthy control subjects, for all standard frequency bands. Comparisons between resting-state MEG sources images and known neurophysiology were provided. Additionally, in simulations and cases with MEG human responses, the results obtained from using conventional beamformer technique were compared with those from Fast-VESTAL, which highlighted the beamformer's problems of signal leaking and distorted source time-courses. © 2013.
MEG Source Imaging Method using Fast L1 Minimum-norm and its Applications to Signals with Brain Noise and Human Resting-state Source Amplitude Images

PubMed Central

Huang, Ming-Xiong; Huang, Charles W.; Robb, Ashley; Angeles, AnneMarie; Nichols, Sharon L.; Baker, Dewleen G.; Song, Tao; Harrington, Deborah L.; Theilmann, Rebecca J.; Srinivasan, Ramesh; Heister, David; Diwakar, Mithun; Canive, Jose M.; Edgar, J. Christopher; Chen, Yu-Han; Ji, Zhengwei; Shen, Max; El-Gabalawy, Fady; Levy, Michael; McLay, Robert; Webb-Murphy, Jennifer; Liu, Thomas T.; Drake, Angela; Lee, Roland R.

2014-01-01

The present study developed a fast MEG source imaging technique based on Fast Vector-based Spatio-Temporal Analysis using a L1-minimum-norm (Fast-VESTAL) and then used the method to obtain the source amplitude images of resting-state magnetoencephalography (MEG) signals for different frequency bands. The Fast-VESTAL technique consists of two steps. First, L1-minimum-norm MEG source images were obtained for the dominant spatial modes of sensor-waveform covariance matrix. Next, accurate source time-courses with millisecond temporal resolution were obtained using an inverse operator constructed from the spatial source images of Step 1. Using simulations, Fast-VESTAL’s performance of was assessed for its 1) ability to localize multiple correlated sources; 2) ability to faithfully recover source time-courses; 3) robustness to different SNR conditions including SNR with negative dB levels; 4) capability to handle correlated brain noise; and 5) statistical maps of MEG source images. An objective pre-whitening method was also developed and integrated with Fast-VESTAL to remove correlated brain noise. Fast-VESTAL’s performance was then examined in the analysis of human mediannerve MEG responses. The results demonstrated that this method easily distinguished sources in the entire somatosensory network. Next, Fast-VESTAL was applied to obtain the first whole-head MEG source-amplitude images from resting-state signals in 41 healthy control subjects, for all standard frequency bands. Comparisons between resting-state MEG sources images and known neurophysiology were provided. Additionally, in simulations and cases with MEG human responses, the results obtained from using conventional beamformer technique were compared with those from Fast-VESTAL, which highlighted the beamformer’s problems of signal leaking and distorted source time-courses. PMID:24055704
Rain Fade Compensation for Ka-Band Communications Satellites

NASA Technical Reports Server (NTRS)

Mitchell, W. Carl; Nguyen, Lan; Dissanayake, Asoka; Markey, Brian; Le, Anh

1997-01-01

This report provides a review and evaluation of rain fade measurement and compensation techniques for Ka-band satellite systems. This report includes a description of and cost estimates for performing three rain fade measurement and compensation experiments. The first experiment deals with rain fade measurement techniques while the second one covers the rain fade compensation techniques. The third experiment addresses a feedback flow control technique for the ABR service (for ATM-based traffic). The following conclusions were observed in this report; a sufficient system signal margin should be allocated for all carriers in a network, that is a fixed clear-sky margin should be typically in the range of 4-5 dB and should be more like 15 dB in the up link for moderate and heavy rain zones; to obtain a higher system margin it is desirable to combine the uplink power control technique with the technique that implements the source information rate and FEC code rate changes resulting in a 4-5 dB increase in the dynamic part of the system margin. The experiments would assess the feasibility of the fade measurements and compensation techniques, and ABR feedback control technique.
Sexual development in fish, practical applications for aquaculture.

PubMed

Cnaani, A; Levavi-Sivan, B

2009-01-01

Aquaculture is one of the fastest rising sectors of world food production. Hundreds of fish species are cultured, providing an affordable, high quality food source. Two aspects of sexual development are critically important for the continued improvement of cultured fish stocks: sexual dimorphism and control of reproduction. In this paper, we review the main methods used to control sex determination in fish and their application in some of the most widely cultured species. Specifically, we review the techniques available for the production of all-male, all-female, and sterile populations. Techniques for endocrinological control of reproduction are also discussed. 2009 S. Karger AG, Basel.
Economics of electron beam and electrical discharge processing for post-combustion NO(x) control in internal combustion engines

NASA Astrophysics Data System (ADS)

Penetrante, B. M.

1993-08-01

The physics and chemistry of non-thermal plasma processing for post-combustion NO(x) control in internal combustion engines are discussed. A comparison of electron beam and electrical discharge processing is made regarding their power consumption, radical production, NO(x) removal mechanisms, and by-product formation. Pollution control applications present a good opportunity for transferring pulsed power techniques to the commercial sector. However, unless advances are made to drastically reduce the price and power consumption of electron beam sources and pulsed power systems, these plasma techniques will not become commercially competitive with conventional thermal or surface-catalytic methods.
Nonpoint sources as external threats to coastal water quality: lessons from Park Service experience

USGS Publications Warehouse

Burroughs, R.H.

1993-01-01

Program design for nonpoint source control was considered through an analogous problem, external threats to national parks. Nonpoint sources are diffuse land activities that degrade water quality, and recent federal legislation seeks to limit them in coastal areas. External threats occur outside a park boundary but affect the purposes for, or resources within, a park. They have been subject to federal management for many decades. Nonpoint sources are a class of external threat. Therefore, programs to limit them should consider techniques used in part protection. These park techniques include 'hard approaches', which rely on power, usually through legal devices, and 'soft approaches', which utilize shared values and objectives. A linked approach, as exemplified at the Cape Cod National Seashore, appears most promising. In a linked approach, if a soft approach fails, the manager of the protected unit is empowered to take an alternative hard action to protect the resource.

PM RESEARCH

EPA Science Inventory

Activity Area (F03): PM Implementation NRMRL conducts research to improve the techniques used to quantify PM and PM precursor emissions from stationary, mobile, and fugitive sources and investigates the performance and cost of innovative control technology systems. The emission...
A step-by-step solution for embedding user-controlled cines into educational Web pages.

PubMed

Cornfeld, Daniel

2008-03-01

The objective of this article is to introduce a simple method for embedding user-controlled cines into a Web page using a simple JavaScript. Step-by-step instructions are included and the source code is made available. This technique allows the creation of portable Web pages that allow the user to scroll through cases as if seated at a PACS workstation. A simple JavaScript allows scrollable image stacks to be included on Web pages. With this technique, you can quickly and easily incorporate entire stacks of CT or MR images into online teaching files. This technique has the potential for use in case presentations, online didactics, teaching archives, and resident testing.
[Application of THz technology to nondestructive detection of agricultural product quality].

PubMed

Jiang, Yu-ying; Ge, Hong-yi; Lian, Fei-yu; Zhang, Yuan; Xia, Shan-hong

2014-08-01

With recent development of THz sources and detector, applications of THz radiation to nondestructive testing and quality control have expanded in many fields, such as agriculture, safety inspection and quality control, medicine, biochemistry, communication etc. Compared with other detection technique, being a new kind of technique, THz radiation has low energy, good perspectivity, and high signal-to-noise ratio, and thus can obtain physical, chemical and biological information. This paper first introduces the basic concept of THz radiation and the major properties, then gives an extensive review of recent research progress in detection of the quality of agricultural products via THz technique, analyzes the existing shortcomings of THz detection and discusses the outlook of potential application, finally proposes the new application of THz technique to detection of quality of stored grain.
Forward model with space-variant of source size for reconstruction on X-ray radiographic image

NASA Astrophysics Data System (ADS)

Liu, Jin; Liu, Jun; Jing, Yue-feng; Xiao, Bo; Wei, Cai-hua; Guan, Yong-hong; Zhang, Xuan

2018-03-01

The Forward Imaging Technique is a method to solve the inverse problem of density reconstruction in radiographic imaging. In this paper, we introduce the forward projection equation (IFP model) for the radiographic system with areal source blur and detector blur. Our forward projection equation, based on X-ray tracing, is combined with the Constrained Conjugate Gradient method to form a new method for density reconstruction. We demonstrate the effectiveness of the new technique by reconstructing density distributions from simulated and experimental images. We show that for radiographic systems with source sizes larger than the pixel size, the effect of blur on the density reconstruction is reduced through our method and can be controlled within one or two pixels. The method is also suitable for reconstruction of non-homogeneousobjects.
Automatic recognition of light source from color negative films using sorting classification techniques

NASA Astrophysics Data System (ADS)

Sanger, Demas S.; Haneishi, Hideaki; Miyake, Yoichi

1995-08-01

This paper proposed a simple and automatic method for recognizing the light sources from various color negative film brands by means of digital image processing. First, we stretched the image obtained from a negative based on the standardized scaling factors, then extracted the dominant color component among red, green, and blue components of the stretched image. The dominant color component became the discriminator for the recognition. The experimental results verified that any one of the three techniques could recognize the light source from negatives of any film brands and all brands greater than 93.2 and 96.6% correct recognitions, respectively. This method is significant for the automation of color quality control in color reproduction from color negative film in mass processing and printing machine.
Locating and Quantifying Broadband Fan Sources Using In-Duct Microphones

NASA Technical Reports Server (NTRS)

Dougherty, Robert P.; Walker, Bruce E.; Sutliff, Daniel L.

2010-01-01

In-duct beamforming techniques have been developed for locating broadband noise sources on a low-speed fan and quantifying the acoustic power in the inlet and aft fan ducts. The NASA Glenn Research Center's Advanced Noise Control Fan was used as a test bed. Several of the blades were modified to provide a broadband source to evaluate the efficacy of the in-duct beamforming technique. Phased arrays consisting of rings and line arrays of microphones were employed. For the imaging, the data were mathematically resampled in the frame of reference of the rotating fan. For both the imaging and power measurement steps, array steering vectors were computed using annular duct modal expansions, selected subsets of the cross spectral matrix elements were used, and the DAMAS and CLEAN-SC deconvolution algorithms were applied.
Techniques and instrumentation for the measurement of transient sound energy flux

NASA Astrophysics Data System (ADS)

Watkinson, P. S.; Fahy, F. J.

1983-12-01

The evaluation of sound intensity distributions, and sound powers, of essentially continuous sources such as automotive engines, electric motors, production line machinery, furnaces, earth moving machinery and various types of process plants were studied. Although such systems are important sources of community disturbance and, to a lesser extent, of industrial health hazard, the most serious sources of hearing hazard in industry are machines operating on an impact principle, such as drop forges, hammers and punches. Controlled experiments to identify major noise source regions and mechanisms are difficult because it is normally impossible to install them in quiet, anechoic environments. The potential for sound intensity measurement to provide a means of overcoming these difficulties has given promising results, indicating the possibility of separation of directly radiated and reverberant sound fields. However, because of the complexity of transient sound fields, a fundamental investigation is necessary to establish the practicability of intensity field decomposition, which is basic to source characterization techniques.
Suppression of ambipolar current in tunnel FETs using drain-pocket: Proposal and analysis

NASA Astrophysics Data System (ADS)

Garg, Shelly; Saurabh, Sneh

2018-01-01

In this paper, we investigate the impact of a drain-pocket (DP) adjacent to the drain region in Tunnel Field-Effect Transistors (TFETs) to effectively suppress the ambipolar current. Using calibrated two-dimensional device simulation, we examine the impact of DP in Double Gate TFET (DGTFET). We demonstrate the superiority of the DP technique over the existing techniques in controlling the ambipolar current. In particular, the addition of DP to a TFET is able to fully suppress the ambipolar current even when TFET is biased at high negative gate voltages and drain doping is kept as high as the source doping. Moreover, adding DP is complementary to the well-known technique of employ-ing source-pocket (SP) in a TFET since both need similar doping type and doping concentration.
The design and implementation of hydrographical information management system (HIMS)

NASA Astrophysics Data System (ADS)

Sui, Haigang; Hua, Li; Wang, Qi; Zhang, Anming

2005-10-01

With the development of hydrographical work and information techniques, the large variety of hydrographical information including electronic charts, documents and other materials are widely used, and the traditional management mode and techniques are unsuitable for the development of the Chinese Marine Safety Administration Bureau (CMSAB). How to manage all kinds of hydrographical information has become an important and urgent problem. A lot of advanced techniques including GIS, RS, spatial database management and VR techniques are introduced for solving these problems. Some design principles and key techniques of the HIMS including the mixed mode base on B/S, C/S and stand-alone computer mode, multi-source & multi-scale data organization and management, multi-source data integration and diverse visualization of digital chart, efficient security control strategies are illustrated in detail. Based on the above ideas and strategies, an integrated system named Hydrographical Information Management System (HIMS) was developed. And the HIMS has been applied in the Shanghai Marine Safety Administration Bureau and obtained good evaluation.
Defining the best quality-control systems by design and inspection.

PubMed

Hinckley, C M

1997-05-01

Not all of the many approaches to quality control are equally effective. Nonconformities in laboratory testing are caused basically by excessive process variation and mistakes. Statistical quality control can effectively control process variation, but it cannot detect or prevent most mistakes. Because mistakes or blunders are frequently the dominant source of nonconformities, we conclude that statistical quality control by itself is not effective. I explore the 100% inspection methods essential for controlling mistakes. Unlike the inspection techniques that Deming described as ineffective, the new "source" inspection methods can detect mistakes and enable corrections before nonconformities are generated, achieving the highest degree of quality at a fraction of the cost of traditional methods. Key relationships between task complexity and nonconformity rates are also described, along with cultural changes that are essential for implementing the best quality-control practices.
Development of an interface for an ultrareliable fault-tolerant control system and an electronic servo-control unit

NASA Technical Reports Server (NTRS)

Shaver, Charles; Williamson, Michael

1986-01-01

The NASA Ames Research Center sponsors a research program for the investigation of Intelligent Flight Control Actuation systems. The use of artificial intelligence techniques in conjunction with algorithmic techniques for autonomous, decentralized fault management of flight-control actuation systems is explored under this program. The design, development, and operation of the interface for laboratory investigation of this program is documented. The interface, architecturally based on the Intel 8751 microcontroller, is an interrupt-driven system designed to receive a digital message from an ultrareliable fault-tolerant control system (UFTCS). The interface links the UFTCS to an electronic servo-control unit, which controls a set of hydraulic actuators. It was necessary to build a UFTCS emulator (also based on the Intel 8751) to provide signal sources for testing the equipment.
A fast feedback method to design easy-molding freeform optical system with uniform illuminance and high light control efficiency.

PubMed

Hongtao, Li; Shichao, Chen; Yanjun, Han; Yi, Luo

2013-01-14

A feedback method combined with fitting technique based on variable separation mapping is proposed to design freeform optical systems for an extended LED source with prescribed illumination patterns, especially with uniform illuminance distribution. Feedback process performs well with extended sources, while fitting technique contributes not only to the decrease of pieces of sub-surfaces in discontinuous freeform lenses which may cause loss in manufacture, but also the reduction in the number of feedback iterations. It is proved that light control efficiency can be improved by 5%, while keeping a high uniformity of 82%, with only two feedback iterations and one fitting operation can improve. Furthermore, the polar angle θ and azimuthal angle φ is used to specify the light direction from the light source, and the (θ,φ)-(x,y) based mapping and feedback strategy makes sure that even few discontinuous sections along the equi-φ plane exist in the system, they are perpendicular to the base plane, making it eligible for manufacturing the surfaces using injection molding.
[Groundwater organic pollution source identification technology system research and application].

PubMed

Wang, Xiao-Hong; Wei, Jia-Hua; Cheng, Zhi-Neng; Liu, Pei-Bin; Ji, Yi-Qun; Zhang, Gan

2013-02-01

Groundwater organic pollutions are found in large amount of locations, and the pollutions are widely spread once onset; which is hard to identify and control. The key process to control and govern groundwater pollution is how to control the sources of pollution and reduce the danger to groundwater. This paper introduced typical contaminated sites as an example; then carried out the source identification studies and established groundwater organic pollution source identification system, finally applied the system to the identification of typical contaminated sites. First, grasp the basis of the contaminated sites of geological and hydrogeological conditions; determine the contaminated sites characteristics of pollutants as carbon tetrachloride, from the large numbers of groundwater analysis and test data; then find the solute transport model of contaminated sites and compound-specific isotope techniques. At last, through groundwater solute transport model and compound-specific isotope technology, determine the distribution of the typical site of organic sources of pollution and pollution status; invest identified potential sources of pollution and sample the soil to analysis. It turns out that the results of two identified historical pollution sources and pollutant concentration distribution are reliable. The results provided the basis for treatment of groundwater pollution.
Electronic Flash In Data Acquisition

NASA Astrophysics Data System (ADS)

Miller, C. E.

1982-02-01

Photographic acquisition of data often may be simplified, or the data quality improved upon by employing electronic flash sources with traditional equipment or techniques. The relatively short flash duration compared to movie camera shutters, or to the long integration time of video camera provides improved spatial resolution through blur reduction, particularly important as image movement becomes a significant fraction of film format dimension. Greater accuracy typically is achieved in velocity and acceleration determinations by using a stroboscopic light source rather than a movie camera frame-rate control as a time standard. Electrical efficiency often is an important advantage of electronic flash sources since almost any necessary light level for exposure may be produced, yet the source typically is "off" most of the time. Various synchronization techniques greatly expand the precise control of exposure. Biomechanical and sports equipment studies may involve velocities up to 200 feet-per-second, and often will have associated very rapid actions of interest. The need for brief exposures increases H.s one "ZOOMS in on the action." In golf, for example, the swing may be examined using 100 microsecond (Us) flashes at rates of 60 or 120 flashes-per-second (FPS). Accurate determination of linear and rotational velocity of the ball requires 10 Us flashes at 500-1,000 FPS, while sub-Us flashes at 20,000-50,000 FPS are required to resolve the interaction of the ball and the club, head. Some seldom. used techniques involving streak photography are described, with enhanced results obtained by combining strobe with the usual continuous light source. The combination of strobe and a fast electro-mechanical shutter is considered for Us photography under daylight conditions.
76 FR 72844 - Approval and Promulgation of Air Quality Implementation Plans: South Carolina; Negative...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-28

... has various NO X sources. The 4110 Paper Mill-Coating unit requires Best Available Control Technology... Carolina; Negative Declarations for Groups I, II, III and IV Control Techniques Guidelines; and Reasonably... for Groups I and I CTG. ``EPA-R04-OAR-2010-0018'' for comments regarding the negative declarations for...
Single particle characterization, source apportionment, and aging effects of ambient aerosols in Southern California

NASA Astrophysics Data System (ADS)

Shields, Laura Grace

Composed of a mixture of chemical species and phases and existing in a variety of shapes and sizes, atmospheric aerosols are complex and can have serious influence on human health, the environment, and climate. In order to better understand the impact of aerosols on local to global scales, detailed measurements on the physical and chemical properties of ambient particles are essential. In addition, knowing the origin or the source of the aerosols is important for policymakers to implement targeted regulations and effective control strategies to reduce air pollution in their region. One of the most ground breaking techniques in aerosol instrumentation is single particle mass spectrometry (SPMS), which can provide online chemical composition and size information on the individual particle level. The primary focus of this work is to further improve the ability of one specific SPMS technique, aerosol time-of-flight mass spectrometry (ATOFMS), for the use of identifying the specific origin of ambient aerosols, which is known as source apportionment. The ATOFMS source apportionment method utilizes a library of distinct source mass spectral signatures to match the chemical information of the single ambient particles. The unique signatures are obtained in controlled source characterization studies, such as with the exhaust emissions of heavy duty diesel vehicles (HDDV) operating on a dynamometer. The apportionment of ambient aerosols is complicated by the chemical and physical processes an individual particle can undergo as it spends time in the atmosphere, which is referred to as "aging" of the aerosol. Therefore, the performance of the source signature library technique was investigated on the ambient dataset of the highly aged environment of Riverside, California. Additionally, two specific subsets of the Riverside dataset (ultrafine particles and particles containing trace metals), which are known to cause adverse health effects, were probed in greater detail. Finally, the impact of large wildfires on the ambient levels of particulate matter in Southern California is discussed. The results of this work provide insight into single particles impacting the Southern California region, the relative source contributions to this region, and finally an examination of how atmospheric aging influences the ability to perform source apportionment.
Oxygen isotopes as a tracer of phosphate sources and cycling in aquatic systems (Invited)

NASA Astrophysics Data System (ADS)

Young, M. B.; Kendall, C.; Paytan, A.

2013-12-01

The oxygen isotopic composition of phosphate can provide valuable information about sources and processes affecting phosphorus as it moves through hydrologic systems. Applications of this technique in soil and water have become more common in recent years due to improvements in extraction methods and instrument capabilities, and studies in multiple aquatic environments have demonstrated that some phosphorus sources may have distinct isotopic compositions within a given system. Under normal environmental conditions, the oxygen-phosphorus bonds in dissolved inorganic phosphate (DIP) can only be broken by enzymatic activity. Biological cycling of DIP will bring the phosphate oxygen into a temperature-dependent equilibrium with the surrounding water, overprinting any existing isotopic source signals. However, studies conducted in a wide range of estuarine, freshwater, and groundwater systems have found that the phosphate oxygen is often out of biological equilibrium with the water, suggesting that it is common for at least a partial isotopic source signal to be retained in aquatic systems. Oxygen isotope analysis on various potential phosphate sources such as synthetic and organic fertilizers, animal waste, detergents, and septic/wastewater treatment plant effluents show that these sources span a wide range of isotopic compositions, and although there is considerable overlap between the source groups, sources may be isotopically distinct within a given study area. Recent soil studies have shown that isotopic analysis of phosphate oxygen is also useful for understanding microbial cycling across different phosphorus pools, and may provide insights into controls on phosphorus leaching. Combining stable isotope information from soil and water studies will greatly improve our understanding of complex phosphate cycling, and the increasing use of this isotopic technique across different environments will provide new information regarding anthropogenic phosphate inputs and controls on biological cycling within hydrologic systems.
A Review of Heating and Temperature Control in Microfluidic Systems: Techniques and Applications

PubMed Central

Miralles, Vincent; Huerre, Axel; Malloggi, Florent; Jullien, Marie-Caroline

2013-01-01

This review presents an overview of the different techniques developed over the last decade to regulate the temperature within microfluidic systems. A variety of different approaches has been adopted, from external heating sources to Joule heating, microwaves or the use of lasers to cite just a few examples. The scope of the technical solutions developed to date is impressive and encompasses for instance temperature ramp rates ranging from 0.1 to 2,000 °C/s leading to homogeneous temperatures from −3 °C to 120 °C, and constant gradients from 6 to 40 °C/mm with a fair degree of accuracy. We also examine some recent strategies developed for applications such as digital microfluidics, where integration of a heating source to generate a temperature gradient offers control of a key parameter, without necessarily requiring great accuracy. Conversely, Temperature Gradient Focusing requires high accuracy in order to control both the concentration and separation of charged species. In addition, the Polymerase Chain Reaction requires both accuracy (homogeneous temperature) and integration to carry out demanding heating cycles. The spectrum of applications requiring temperature regulation is growing rapidly with increasingly important implications for the physical, chemical and biotechnological sectors, depending on the relevant heating technique. PMID:26835667
The '333' integrated strategy for effective pollution control and its application to the heavily polluted Jialu River in north China.

PubMed

Huang, Yu; Sun, Jie; Li, Aimin; Xie, Xianchuan

2018-05-01

In this study, an integrated approach named the '333' strategy was applied to pollution control in the Jialu River, in northern China, which is heavily burdened with anthropogenic pollution. Due to a deficiency of the natural ecological inflow, the Jialu River receives predominantly industrial and municipal effluent. The '333' strategy is composed of three steps of pollution control including industrial point-source pollution control, advanced treatment of municipal wastewater, and ecological restoration; three increased stringency emission standards; and three stages of reclamation. Phase 1 of the '333' strategy focuses on industrial point-source pollution control; phase 2 aims to harness municipal wastewater and minimize sewage effluents using novel techniques for advanced water purification; phase 3 of the '333' strategy focuses on the further purification of effluents flowing into Jialu River with the employment of an engineering-based ecological restoration project. The application of the '333' strategy resulted in the development of novel techniques for water purification including modified magnetic resins (NDMP resin), a two-stage internal circulation anaerobic reactor (IC reactor) and an ecological restoration system. The results indicate that water quality in the river was significantly improved, with increased concentrations of dissolved oxygen (DO), as well as reduction of COD by 42.8% and NH 3 -N by 61.4%. In addition, it was observed that the total population of phytoplankton in treated river water notably increased from only one prior to restoration to 8 following restoration. This system also provides a tool for pollution control of other similar industrial and anthropogenic source polluted rivers.
Headspace analysis of volatile organic compounds from ethanolic systems by direct APCI-MS

NASA Astrophysics Data System (ADS)

Aznar, Margarita; Tsachaki, Maroussa; Linforth, Robert S. T.; Ferreira, Vicente; Taylor, Andrew J.

2004-12-01

Measuring the dynamic release of aroma compounds from ethanolic solutions by direct gas phase mass spectrometry (MS) techniques is an important technique for flavor chemists but presents technical difficulties as the changing ethanol concentration in the source makes quantitative measurements impossible. The effect of adding ethanol into the source via the sweep gas (0-565 [mu]L ethanol/L N2), to act as the proton transfer reagent ion and thereby control ionization was studied. With increasing concentrations of ethanol in the source, the water ions were replaced by ethanol ions above 3.2 [mu]L/L. The effect of source ethanol on the ionization of eleven aroma compounds was then measured. Some compounds showed reduced signal (10-40%), others increased signal (150-400%) when ionized via ethanol reagent ions compared to water reagent ions. Noise also increased in most cases so there was no overall increase in sensitivity. Providing the ethanol concentration in the source was >6.5 [mu]L/L N2 and maintained at a fixed value, ionization was consistent and quantitative. The technique was successfully applied to measure the partition of the test volatile compounds from aqueous and 12% ethanol solutions at equilibrium. Ethanolic solutions decreased the partition coefficient of most of the aroma compounds, as a function of hydrophobicity.

Application of Semi Active Control Techniques to the Damping Suppression Problem of Solar Sail Booms

NASA Technical Reports Server (NTRS)

Adetona, O.; Keel, L. H.; Whorton, M. S.

2007-01-01

Solar sails provide a propellant free form for space propulsion. These are large flat surfaces that generate thrust when they are impacted by light. When attached to a space vehicle, the thrust generated can propel the space vehicle to great distances at significant speeds. For optimal performance the sail must be kept from excessive vibration. Active control techniques can provide the best performance. However, they require an external power-source that may create significant parasitic mass to the solar sail. However, solar sails require low mass for optimal performance. Secondly, active control techniques typically require a good system model to ensure stability and performance. However, the accuracy of solar sail models validated on earth for a space environment is questionable. An alternative approach is passive vibration techniques. These do not require an external power supply, and do not destabilize the system. A third alternative is referred to as semi-active control. This approach tries to get the best of both active and passive control, while avoiding their pitfalls. In semi-active control, an active control law is designed for the system, and passive control techniques are used to implement it. As a result, no external power supply is needed so the system is not destabilize-able. Though it typically underperforms active control techniques, it has been shown to out-perform passive control approaches and can be unobtrusively installed on a solar sail boom. Motivated by this, the objective of this research is to study the suitability of a Piezoelectric (PZT) patch actuator/sensor based semi-active control system for the vibration suppression problem of solar sail booms. Accordingly, we develop a suitable mathematical and computer model for such studies and demonstrate the capabilities of the proposed approach with computer simulations.
Contamination assessment and control in scientific satellites

NASA Technical Reports Server (NTRS)

Naumann, R. J.

1973-01-01

Techniques for assessment and control of the contamination environment for both particulates and condensible vapors in the vicinity of spacecraft are developed. An analysis of the deposition rate on critical surfaces is made considering sources within the line of sight of the surface in question as well as those obscured from the line of sight. The amount of contamination returned by collision with the surrounding atmosphere is estimated. Scattering and absorption from the induced atmosphere of gases and particulates around the spacecraft are estimated. Finally, design techniques developed for Skylab to reduce the contamination environment to an acceptable level are discussed.
Method And Apparatus For Evaluatin Of High Temperature Superconductors

DOEpatents

Fishman, Ilya M.; Kino, Gordon S.

1996-11-12

A technique for evaluation of high-T.sub.c superconducting films and single crystals is based on measurement of temperature dependence of differential optical reflectivity of high-T.sub.c materials. In the claimed method, specific parameters of the superconducting transition such as the critical temperature, anisotropy of the differential optical reflectivity response, and the part of the optical losses related to sample quality are measured. The apparatus for performing this technique includes pump and probe sources, cooling means for sweeping sample temperature across the critical temperature and polarization controller for controlling a state of polarization of a probe light beam.
Ultra-High Sensitivity Techniques for the Determination of 3 He /4 He Abundances in Helium by Accelerator Mass Spectrometry

NASA Astrophysics Data System (ADS)

Mumm, H. P.; Huber, M.; Bauder, W.; Abrams, N.; Deibel, C.; Huffer, C.; Huffman, P.; Schelhammer, K.; Janssens, R.; Jiang, C.; Scott, R.; Pardo, R.; Rehm, K.; Vondrasek, R.; Swank, C.; O'Shaughnessy, C.; Paul, M.; Yang, L.

2017-01-01

We report the development of an Accelerator Mass Spectrometry technique to measure the 3He/4He isotopic ratio using a radio frequency (RF) discharge source and the ATLAS facility at Argonne National Laboratory. Control over 3He/4He ratio in helium several orders of magnitude lower than natural abundance is critical for neutron lifetime and source experiments using liquid helium. Due to low ultimate beam currents, the ATLAS accelerator and beam line were tuned using a succession of species of the same M/q. A unique RF source was developed for the experiment due to large natural 3He backgrounds. Analog H_3 + and DH + molecular ions are eliminated by dissociation via a gold stripper foil near the detector. The stripped ions were dispersed in a magnetic spectrograph and 3He2 + ions counted in the focal plane detector. This technique is sensitive to 3 He /4 He ratios in the regime of 10-12 with backgrounds that appear to be below 10-14. The techniques used to reduce the backgrounds and remaining outstanding problems will be presented along with results from measurements on high purity 4He samples.
Analytical study of acoustic response of a semireverberant enclosure with application to active noise control

NASA Technical Reports Server (NTRS)

Parrott, T. L.; Schein, D. B.; Gridley, D.

1985-01-01

The acoustic response of a semireverberant enclosure with two interacting, velocity-prescribed source distributions was analyzed using standard modal analysis techniques with a view toward a better understanding of active noise control. Different source and enclosure dimensions, source separations, and single-wall admittances were studied over representative frequency bandwidths of 10 Hz with source relative phase as a parameter. Results indicate that power radiated into the enclosure agree qualitatively with the spatial average of the mean square pressure, even though the reverberant field is nondiffuse. Decreases in acoustic power can therefore be used to estimate global noise reduction in a nondiffuse semireverberant environment. As might be expected, parametric studies indicate that maximum power reductions of up to 25 dB can be achieved when secondary and primary sources are compact and closely spaced. Although less success is achieved with increasing frequency and source separation or size, significant suppression of up to 8 dB still occurs over the 1 to 2 Hz bandwidth.
Laser-induced contamination control for high-power lasers in space-based LIDAR missions

NASA Astrophysics Data System (ADS)

Alves, Jorge; Pettazzi, Federico; Tighe, Adrian; Wernham, Denny

2017-11-01

In the framework of the ADM-Aeolus satellite mission, successful test campaigns have been performed in ESTEC's laser laboratory, and the efficiency of several mitigation techniques against Laser-Induced Contamination (LIC) have been demonstrated for the ALADIN laser. These techniques include the standard contamination control methods of materials identification with particular tendency to cause LIC, reduction of the outgassing of organic materials by vacuum bake-out and shielding of optical surfaces from the contamination sources. Also novel mitigation methods such as in-situ cleaning via partial pressures, or the usage of molecular absorbers were demonstrated. In this context, a number of highly sensitive optical measurement techniques have been developed and tested to detect and monitor LIC deposits at nanometre level.
Probing the critical zone using passive- and active-source estimates of subsurface shear-wave velocities

NASA Astrophysics Data System (ADS)

Callahan, R. P.; Taylor, N. J.; Pasquet, S.; Dueker, K. G.; Riebe, C. S.; Holbrook, W. S.

2016-12-01

Geophysical imaging is rapidly becoming popular for quantifying subsurface critical zone (CZ) architecture. However, a diverse array of measurements and measurement techniques are available, raising the question of which are appropriate for specific study goals. Here we compare two techniques for measuring S-wave velocities (Vs) in the near surface. The first approach quantifies Vs in three dimensions using a passive source and an iterative residual least-squares tomographic inversion. The second approach uses a more traditional active-source seismic survey to quantify Vs in two dimensions via a Monte Carlo surface-wave dispersion inversion. Our analysis focuses on three 0.01 km2 study plots on weathered granitic bedrock in the Southern Sierra Critical Zone Observatory. Preliminary results indicate that depth-averaged velocities from the two methods agree over the scales of resolution of the techniques. While the passive- and active-source techniques both quantify Vs, each method has distinct advantages and disadvantages during data acquisition and analysis. The passive-source method has the advantage of generating a three dimensional distribution of subsurface Vs structure across a broad area. Because this method relies on the ambient seismic field as a source, which varies unpredictably across space and time, data quality and depth of investigation are outside the control of the user. Meanwhile, traditional active-source surveys can be designed around a desired depth of investigation. However, they only generate a two dimensional image of Vs structure. Whereas traditional active-source surveys can be inverted quickly on a personal computer in the field, passive source surveys require significantly more computations, and are best conducted in a high-performance computing environment. We use data from our study sites to compare these methods across different scales and to explore how these methods can be used to better understand subsurface CZ architecture.
An event-based vibration control for a two-link flexible robotic arm: Numerical and experimental observations

NASA Astrophysics Data System (ADS)

Özer, Abdullah; Eren Semercigil, S.

2008-06-01

Flexible robot manipulators have numerous advantages over their rigid counterparts. They have increased payload-to-weight ratio, they run at higher speeds, use less energy and smaller actuators, and they are safer during interaction with their environments. On the other hand, light design combined with external effects result in components which can oscillate with excessive amplitudes. These oscillations cause deviation from the desired path and long idle periods between tasks in order to perform the intended operation safely and accurately. This paper is on an investigation into the effectiveness of a vibration control technique for a two-link flexible robotic arm. Variable stiffness control (VSC) technique is used to control the excessive oscillations. Owing to its dissipative nature, the technique is stable, it is relatively insensitive to significant parameter changes and suitable to be implemented on existing robots. This research considers that the source of the flexibility is either the joints or the links or both. Simulation results of the response of the arm are presented to show the versatility of the proposed control technique. Experiments are performed on a laboratory prototype and the results are presented to test the validity of simulations.
Graphene Synthesis by Plasma-Enhanced CVD Growth with Ethanol

DOE PAGES

Campo, Teresa; Cotto, María; Márquez, Francisco; ...

2016-03-01

A modified route to synthesize graphene flakes is proposed using the Chemical Vapor Deposition (CVD) technique, by using copper substrates as supports. The carbon source used was ethanol, the synthesis temperature was 950°C and the pressure was controlled along the whole process. In this CVD synthesis process the incorporation of the carbon source was produced at low pressure and 950°C inducing the appearance of a plasma blue flash inside the quartz tube. Apparently, the presence of this plasma blue flash is required for obtaining graphene flakes. The synthesized graphene was characterized by different techniques, showing the presence of non-oxidized graphenemore » with high purity.« less
Resolving z ~2 galaxy using adaptive coadded source plane reconstruction

NASA Astrophysics Data System (ADS)

Sharma, Soniya; Richard, Johan; Kewley, Lisa; Yuan, Tiantian

2018-06-01

Natural magnification provided by gravitational lensing coupled with Integral field spectrographic observations (IFS) and adaptive optics (AO) imaging techniques have become the frontier of spatially resolved studies of high redshift galaxies (z>1). Mass models of gravitational lenses hold the key for understanding the spatially resolved source–plane (unlensed) physical properties of the background lensed galaxies. Lensing mass models very sensitively control the accuracy and precision of source-plane reconstructions of the observed lensed arcs. Effective source-plane resolution defined by image-plane (observed) point spread function (PSF) makes it challenging to recover the unlensed (source-plane) surface brightness distribution.We conduct a detailed study to recover the source-plane physical properties of z=2 lensed galaxy using spatially resolved observations from two different multiple images of the lensed target. To deal with PSF’s from two data sets on different multiple images of the galaxy, we employ a forward (Source to Image) approach to merge these independent observations. Using our novel technique, we are able to present a detailed analysis of the source-plane dynamics at scales much better than previously attainable through traditional image inversion methods. Moreover, our technique is adapted to magnification, thus allowing us to achieve higher resolution in highly magnified regions of the source. We find that this lensed system is highly evident of a minor merger. In my talk, I present this case study of z=2 lensed galaxy and also discuss the applications of our algorithm to study plethora of lensed systems, which will be available through future telescopes like JWST and GMT.
Induction motor speed control using varied duty cycle terminal voltage via PI controller

NASA Astrophysics Data System (ADS)

Azwin, A.; Ahmed, S.

2018-03-01

This paper deals with the PI speed controller for the three-phase induction motor using PWM technique. The PWM generated signal is utilized for voltage source inverter with an optimal duty cycle on a simplified induction motor model. A control algorithm for generating PWM control signal is developed. Obtained results shows that the steady state error and overshoot of the developed system is in the limit under different speed and load condition. The robustness of the control performance would be potential for induction motor performance improvement.
Techniques used for the analysis of oculometer eye-scanning data obtained from an air traffic control display

NASA Technical Reports Server (NTRS)

Crawford, Daniel J.; Burdette, Daniel W.; Capron, William R.

1993-01-01

The methodology and techniques used to collect and analyze look-point position data from a real-time ATC display-format comparison experiment are documented. That study compared the delivery precision and controller workload of three final approach spacing aid display formats. Using an oculometer, controller lookpoint position data were collected, associated with gaze objects (e.g., moving aircraft) on the ATC display, and analyzed to determine eye-scan behavior. The equipment involved and algorithms for saving, synchronizing with the ATC simulation output, and filtering the data are described. Target (gaze object) and cross-check scanning identification algorithms are also presented. Data tables are provided of total dwell times, average dwell times, and cross-check scans. Flow charts, block diagrams, file record descriptors, and source code are included. The techniques and data presented are intended to benefit researchers in other studies that incorporate non-stationary gaze objects and oculometer equipment.
Real-time spectral characterization of a photon pair source using a chirped supercontinuum seed.

PubMed

Erskine, Jennifer; England, Duncan; Kupchak, Connor; Sussman, Benjamin

2018-02-15

Photon pair sources have wide ranging applications in a variety of quantum photonic experiments and protocols. Many of these protocols require well controlled spectral correlations between the two output photons. However, due to low cross-sections, measuring the joint spectral properties of photon pair sources has historically been a challenging and time-consuming task. Here, we present an approach for the real-time measurement of the joint spectral properties of a fiber-based four wave mixing source. We seed the four wave mixing process using a broadband chirped pulse, studying the stimulated process to extract information regarding the spontaneous process. In addition, we compare stimulated emission measurements with the spontaneous process to confirm the technique's validity. Joint spectral measurements have taken many hours historically and several minutes with recent techniques. Here, measurements have been demonstrated in 5-30 s depending on resolution, offering substantial improvement. Additional benefits of this approach include flexible resolution, large measurement bandwidth, and reduced experimental overhead.
Payload/orbiter contamination control requirement study

NASA Technical Reports Server (NTRS)

Bareiss, L. E.; Ress, E. B.

1975-01-01

The results of a contamination impact analysis upon the spacelab carrier and the spacelab carrier upon some of its potential payloads are presented. These results are based upon contamination computer modeling techniques developed to predict the induced environment for spacelab and to provide the basis for evaluation of the predicted environment against the current on orbit contamination control criteria as specified for payloads. Those spacelab carrier contamination sources evaluated against the stated contamination control criteria were outgassing/offgassing of the major nonmetallic thermal control coating of the spacelab carriers, spacelab core and experiment module and tunnel cabin atmosphere leakage, avionics bay vent, spacelab condensate vent, random particulate sloughing, and the return flux of the molecular content of these sources from the gas-gas interactions with the ambient orbital environment. It is indicated that the spacelab carrier can meet the intent of the contamination control criteria through incorporating known contamination control practices.
Rapid screening of basic colorants in processed vegetables through mass spectrometry using an interchangeable thermal desorption electrospray ionization source.

PubMed

Chao, Yu-Ying; Chen, Yen-Ling; Lin, Hong-Yi; Huang, Yeou-Lih

2018-06-20

Thermal desorption electrospray ionization/mass spectrometry (TD-ESI-MS) employing a quickly interchangeable ionization source is a relatively new ambient ionization mass spectrometric technique that has had, to date, only a limited number of applications related to food safety control. With reallocation of resources, this direct-analysis technique has had wider use in food analysis when operated in dual-working mode (pretreatment-free qualitative screening and conventional quantitative confirmation) after switching to an ambient ionization source from a traditional atmospheric pressure ionization source. Herein, we describe the benefits and challenges associated with the use of a TD-ESI source to detect adulterants in processed vegetables (PVs), as a proof-of-concept for the detection of basic colorants. While TD-ESI can offer direct qualitative screening analyses for PVs with detection capabilities lower than those provided with liquid chromatography/UV detection within 30 s, the use of TD-ESI for semi-quantification is applicable only for homogeneous food matrices. Copyright © 2018 Elsevier B.V. All rights reserved.
Impact of head models in N170 component source imaging: results in control subjects and ADHD patients

NASA Astrophysics Data System (ADS)

Beltrachini, L.; Blenkmann, A.; von Ellenrieder, N.; Petroni, A.; Urquina, H.; Manes, F.; Ibáñez, A.; Muravchik, C. H.

2011-12-01

The major goal of evoked related potential studies arise in source localization techniques to identify the loci of neural activity that give rise to a particular voltage distribution measured on the surface of the scalp. In this paper we evaluate the effect of the head model adopted in order to estimate the N170 component source in attention deficit hyperactivity disorder (ADHD) patients and control subjects, considering faces and words stimuli. The standardized low resolution brain electromagnetic tomography algorithm (sLORETA) is used to compare between the three shell spherical head model and a fully realistic model based on the ICBM-152 atlas. We compare their variance on source estimation and analyze the impact on the N170 source localization. Results show that the often used three shell spherical model may lead to erroneous solutions, specially on ADHD patients, so its use is not recommended. Our results also suggest that N170 sources are mainly located in the right occipital fusiform gyrus for faces stimuli and in the left occipital fusiform gyrus for words stimuli, for both control subjects and ADHD patients. We also found a notable decrease on the N170 estimated source amplitude on ADHD patients, resulting in a plausible marker of the disease.
Advanced Modeling and Uncertainty Quantification for Flight Dynamics; Interim Results and Challenges

NASA Technical Reports Server (NTRS)

Hyde, David C.; Shweyk, Kamal M.; Brown, Frank; Shah, Gautam

2014-01-01

As part of the NASA Vehicle Systems Safety Technologies (VSST), Assuring Safe and Effective Aircraft Control Under Hazardous Conditions (Technical Challenge #3), an effort is underway within Boeing Research and Technology (BR&T) to address Advanced Modeling and Uncertainty Quantification for Flight Dynamics (VSST1-7). The scope of the effort is to develop and evaluate advanced multidisciplinary flight dynamics modeling techniques, including integrated uncertainties, to facilitate higher fidelity response characterization of current and future aircraft configurations approaching and during loss-of-control conditions. This approach is to incorporate multiple flight dynamics modeling methods for aerodynamics, structures, and propulsion, including experimental, computational, and analytical. Also to be included are techniques for data integration and uncertainty characterization and quantification. This research shall introduce new and updated multidisciplinary modeling and simulation technologies designed to improve the ability to characterize airplane response in off-nominal flight conditions. The research shall also introduce new techniques for uncertainty modeling that will provide a unified database model comprised of multiple sources, as well as an uncertainty bounds database for each data source such that a full vehicle uncertainty analysis is possible even when approaching or beyond Loss of Control boundaries. Methodologies developed as part of this research shall be instrumental in predicting and mitigating loss of control precursors and events directly linked to causal and contributing factors, such as stall, failures, damage, or icing. The tasks will include utilizing the BR&T Water Tunnel to collect static and dynamic data to be compared to the GTM extended WT database, characterizing flight dynamics in off-nominal conditions, developing tools for structural load estimation under dynamic conditions, devising methods for integrating various modeling elements into a real-time simulation capability, generating techniques for uncertainty modeling that draw data from multiple modeling sources, and providing a unified database model that includes nominal plus increments for each flight condition. This paper presents status of testing in the BR&T water tunnel and analysis of the resulting data and efforts to characterize these data using alternative modeling methods. Program challenges and issues are also presented.
Taguchi's technique: an effective method for improving X-ray medical radiographic screen performance.

PubMed

Vlachogiannis, J G

2003-01-01

Taguchi's technique is a helpful tool to achieve experimental optimization of a large number of decision variables with a small number of off-line experiments. The technique appears to be an ideal tool for improving the performance of X-ray medical radiographic screens under a noise source. Currently there are very many guides available for improving the efficiency of X-ray medical radiographic screens. These guides can be refined using a second-stage parameter optimization. based on Taguchi's technique, selecting the optimum levels of controllable X-ray radiographic screen factors. A real example of the proposed technique is presented giving certain performance criteria. The present research proposes the reinforcement of X-ray radiography by Taguchi's technique as a novel hardware mechanism.
Is Wildlife Fertility Control Always Humane?

PubMed Central

Hampton, Jordan O.; Hyndman, Timothy H.; Barnes, Anne; Collins, Teresa

2015-01-01

Simple Summary There are various fertility control methods (modalities) currently available that aim to reduce the abundance of problematic free-ranging mammalian wildlife. Here, we propose that dissimilarities in the mechanism of action indicate these methods produce great variation in animal welfare outcomes. We present a framework to assist managers in minimising animal welfare risks. Abstract Investigation of fertility control techniques to reduce reproductive rates in wildlife populations has been the source of much research. Techniques targeting wildlife fertility have been diverse. Most research into fertility control methods has focused upon efficacy, with few studies rigorously assessing animal welfare beyond opportunistic anecdote. However, fertility control techniques represent several very different mechanisms of action (modalities), each with their own different animal welfare risks. We provide a review of the mechanisms of action for fertility control methods, and consider the role of manipulation of reproductive hormones (“endocrine suppression”) for the long-term ability of animals to behave normally. We consider the potential welfare costs of animal manipulation techniques that are required to administer fertility treatments, including capture, restraint, surgery and drug delivery, and the requirement for repeated administration within the lifetime of an animal. We challenge the assumption that fertility control modalities generate similar and desirable animal welfare outcomes, and we argue that knowledge of reproductive physiology and behaviour should be more adeptly applied to wild animal management decisions. We encourage wildlife managers to carefully assess long-term behavioural risks, associated animal handling techniques, and the importance of positive welfare states when selecting fertility control methods as a means of population control. PMID:26506395
Air Pollution Surveillance Systems

ERIC Educational Resources Information Center

Morgan, George B.; And Others

1970-01-01

Describes atmospheric data monitoring as part of total airpollution control effort. Summarizes types of gaseous, liquid and solid pollutants and their sources; contrast between urban and rural environmental air quality; instrumentation to identify pollutants; and anticipated new non-wet chemical physical and physiochemical techniques tor cetection…

Food toxin detection with atomic force microscope

USDA-ARS?s Scientific Manuscript database

Externally introduced toxins or internal spoilage correlated pathogens and their metabolites are all potential sources of food toxins. To prevent and protect unsafe food, many food toxin detection techniques have been developed to detect various toxins for quality control. Although several routine m...
Techniques for optimal crop selection in a controlled ecological life support system

NASA Technical Reports Server (NTRS)

Mccormack, Ann; Finn, Cory; Dunsky, Betsy

1993-01-01

A Controlled Ecological Life Support System (CELSS) utilizes a plant's natural ability to regenerate air and water while being grown as a food source in a closed life support system. Current plant research is directed toward obtaining quantitative empirical data on the regenerative ability of each species of plant and the system volume and power requirements. Two techniques were adapted to optimize crop species selection while at the same time minimizing the system volume and power requirements. Each allows the level of life support supplied by the plants to be selected, as well as other system parameters. The first technique uses decision analysis in the form of a spreadsheet. The second method, which is used as a comparison with and validation of the first, utilizes standard design optimization techniques. Simple models of plant processes are used in the development of these methods.
Techniques for optimal crop selection in a controlled ecological life support system

NASA Technical Reports Server (NTRS)

Mccormack, Ann; Finn, Cory; Dunsky, Betsy

1992-01-01

A Controlled Ecological Life Support System (CELSS) utilizes a plant's natural ability to regenerate air and water while being grown as a food source in a closed life support system. Current plant research is directed toward obtaining quantitative empirical data on the regenerative ability of each species of plant and the system volume and power requirements. Two techniques were adapted to optimize crop species selection while at the same time minimizing the system volume and power requirements. Each allows the level of life support supplied by the plants to be selected, as well as other system parameters. The first technique uses decision analysis in the form of a spreadsheet. The second method, which is used as a comparison with and validation of the first, utilizes standard design optimization techniques. Simple models of plant processes are used in the development of these methods.
Modulated infrared radiant source

NASA Technical Reports Server (NTRS)

Stewart, W. F.; Edwards, S. F.; Vann, D. S.; Mccormick, R. F.

1981-01-01

A modulated, infrared radiant energy source was developed to calibrate an airborne nadir-viewing pressure modulated radiometer to be used to detect from Earth orbit trace gases in the troposphere. The technique used an 8 cm long, 0.005 cm diameter platinum-iridium wire as an isothermal, thin line radiant energy source maintained at 1200 K. A + or - 20 K signal, oscillating at controllable frequencies from dc to 20 Hz, was superimposed on it. This periodic variation of the line source energy was used to verify the pressure modulated radiometer's capability to distinguish between the signal variations caused by the Earth's background surface and the signal from the atmospheric gases of interest.
Handbook for industrial noise control

NASA Technical Reports Server (NTRS)

1981-01-01

The basic principles of sound, measuring techniques, and instrumentation associated with general purpose noise control are discussed. Means for identifying and characterizing a noise problem so that subsequent work may provide the most efficient and cost effective solution are outlined. A methodology for choosing appropriate noise control materials and the proper implementation of control procedures is detailed. The most significant NASA sponsored contributions to the state of the art development of optimum noise control technologies are described including cases in which aeroacoustics and related research have shed some light on ways of reducing noise generation at its source.
Handbook for industrial noise control

NASA Astrophysics Data System (ADS)

The basic principles of sound, measuring techniques, and instrumentation associated with general purpose noise control are discussed. Means for identifying and characterizing a noise problem so that subsequent work may provide the most efficient and cost effective solution are outlined. A methodology for choosing appropriate noise control materials and the proper implementation of control procedures is detailed. The most significant NASA sponsored contributions to the state of the art development of optimum noise control technologies are described including cases in which aeroacoustics and related research have shed some light on ways of reducing noise generation at its source.
CSAMT Data Processing with Source Effect and Static Corrections, Application of Occam's Inversion, and Its Application in Geothermal System

NASA Astrophysics Data System (ADS)

Hamdi, H.; Qausar, A. M.; Srigutomo, W.

2016-08-01

Controlled source audio-frequency magnetotellurics (CSAMT) is a frequency-domain electromagnetic sounding technique which uses a fixed grounded dipole as an artificial signal source. Measurement of CSAMT with finite distance between transmitter and receiver caused a complex wave. The shifted of the electric field due to the static effect caused elevated resistivity curve up or down and affects the result of measurement. The objective of this study was to obtain data that have been corrected for source and static effects as to have the same characteristic as MT data which are assumed to exhibit plane wave properties. Corrected CSAMT data were inverted to reveal subsurface resistivity model. Source effect correction method was applied to eliminate the effect of the signal source and static effect was corrected by using spatial filtering technique. Inversion method that used in this study is the Occam's 2D Inversion. The results of inversion produces smooth models with a small misfit value, it means the model can describe subsurface conditions well. Based on the result of inversion was predicted measurement area is rock that has high permeability values with rich hot fluid.
Quantification of Gas Emissions from Refinieries, Gas Stations, Oil Wells and Agriculture using Optical Solar Occultation Flux and Tracer Correlation Methods

NASA Astrophysics Data System (ADS)

Mellqvist, J.; Samuelsson, J.; Marianne, E.; Brohede, S.; Andersson, P.; Johansson, J.; Isoz, O.; Tisopulos, L.; Polidori, A.; Pikelnaya, O.

2016-12-01

Industrial volatile organic compound (VOC) emissions may contribute significantly to ozone formation. In order to investigate how much small sources contribute to the VOC concentrations in the Los Angeles metropolitan area a comprehensive emission study has been carried out on behalf of the South Coast Air Quality Management District (SCAQMD). VOC emissions from major sources such as refineries, oil wells, petrol stations oil depots and oil platforms were measured during September and October 2015 using several unique optical methods, including the Solar Occultation Flux method (SOF) and tracer correlation technique based on extractive FTIR and DOAS combined with an open path multi reflection cell. In addition, measurements of ammonia emissions from farming in Chino were demonstrated. The measurements in this study were quality assured by carrying out a controlled source gas release study and side by side measurements with several other techniques. The results from the field campaign show that the emissions from the above mentioned sources are largely underestimated in inventories with potential impact on the air quality in the Los Angeles metropolitan area. The results show that oil and gas production is a very significant VOC emission source. In this presentation the techniques will be discussed together with the main results from the campaign including the quality assurance work.
X-ray generation using carbon nanotubes

NASA Astrophysics Data System (ADS)

Parmee, Richard J.; Collins, Clare M.; Milne, William I.; Cole, Matthew T.

2015-01-01

Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medical and inspection techniques, including computed tomography and tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a considerable level of interest in the development of new fabrication methods. The use of conventional thermionic sources is limited by their slow temporal response and large physical size. In response, field electron emission has emerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined distribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such systems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in carbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional advantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped cathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of some of the commercial progress made towards the realisation of an innovative and disruptive technology.
Simplified Rotation In Acoustic Levitation

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Gaspar, M. S.; Trinh, E. H.

1989-01-01

New technique based on old discovery used to control orientation of object levitated acoustically in axisymmetric chamber. Method does not require expensive equipment like additional acoustic drivers of precisely adjustable amplitude, phase, and frequency. Reflecting object acts as second source of sound. If reflecting object large enough, close enough to levitated object, or focuses reflected sound sufficiently, Rayleigh torque exerted on levitated object by reflected sound controls orientation of object.
Interior Noise

NASA Technical Reports Server (NTRS)

Mixson, John S.; Wilby, John F.

1991-01-01

The generation and control of flight vehicle interior noise is discussed. Emphasis is placed on the mechanisms of transmission through airborne and structure-borne paths and the control of cabin noise by path modification. Techniques for identifying the relative contributions of the various source-path combinations are also discussed along with methods for the prediction of aircraft interior noise such as those based on the general modal theory and statistical energy analysis.
Integrated Broadband Quantum Cascade Laser

NASA Technical Reports Server (NTRS)

Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

2016-01-01

A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.
Quadratic Optimization in the Problems of Active Control of Sound

NASA Technical Reports Server (NTRS)

Loncaric, J.; Tsynkov, S. V.; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

We analyze the problem of suppressing the unwanted component of a time-harmonic acoustic field (noise) on a predetermined region of interest. The suppression is rendered by active means, i.e., by introducing the additional acoustic sources called controls that generate the appropriate anti-sound. Previously, we have obtained general solutions for active controls in both continuous and discrete formulations of the problem. We have also obtained optimal solutions that minimize the overall absolute acoustic source strength of active control sources. These optimal solutions happen to be particular layers of monopoles on the perimeter of the protected region. Mathematically, minimization of acoustic source strength is equivalent to minimization in the sense of L(sub 1). By contrast. in the current paper we formulate and study optimization problems that involve quadratic functions of merit. Specifically, we minimize the L(sub 2) norm of the control sources, and we consider both the unconstrained and constrained minimization. The unconstrained L(sub 2) minimization is certainly the easiest problem to address numerically. On the other hand, the constrained approach allows one to analyze sophisticated geometries. In a special case, we call compare our finite-difference optimal solutions to the continuous optimal solutions obtained previously using a semi-analytic technique. We also show that the optima obtained in the sense of L(sub 2) differ drastically from those obtained in the sense of L(sub 1).
A Power Regulation and Droop Mode Control Method for a Stand-Alone Load Fed from a PV-Current Source Inverter

NASA Astrophysics Data System (ADS)

Khayamy, Mehdy; Ojo, Olorunfemi

2015-04-01

A current source inverter fed from photovoltaic cells is proposed to power an autonomous load when operating under either power regulation or voltage and frequency drooping modes. Input-output linearization technique is applied to the overall nonlinear system to achieve a globally stable system under feasible operating conditions. After obtaining the steady-state model that demarcates the modes of operation, computer Simulation results for variations in irradiance and the load power of the controlled system are generated in which an acceptable dynamic response of the power generator system under the two modes of operation is observed.
Modeling, Development and Control of Multilevel Converters for Power System Application =

NASA Astrophysics Data System (ADS)

Vahedi, Hani

The main goal of this project is to develop a multilevel converter topology to be useful in power system applications. Although many topologies are introduced rapidly using a bunch of switches and isolated dc sources, having a single-dc-source multilevel inverter is still a matter of controversy. In fact, each isolated dc source means a bulky transformer and a rectifier that have their own losses and costs forcing the industries to avoid entering in this topic conveniently. On the other hand, multilevel inverters topologies with single-dc-source require associated controllers to regulate the dc capacitors voltages in order to have multilevel voltage waveform at the output. Thus, a complex controller would not interest investors properly. Consequently, developing a single-dc-source multilevel inverter topology along with a light and reliable voltage control is still a challenging topic to replace the 2-level inverters in the market effectively. The first effort in this project was devoted to the PUC7 inverter to design a simple and yet efficient controller. A new modelling is performed on the PUC7 inverter and it has been simplified to first order system. Afterwards, a nonlinear cascaded controller is designed and applied to regulate the capacitor voltage at 1/3 of the DC source amplitude and to generate 7 identical voltage levels at the output supplying different type of loads such as RL or rectifier harmonic ones. In next work, the PUC5 topology is proposed as a remedy to the PUC7 that requires a complicated controller to operate properly. The capacitor voltage is regulated at half of dc source amplitude to generate 5 voltage levels at the output. Although the 7-level voltage waveform is replaced by a 5-level one in PUC5 topology, it is shown that the PUC5 needs a very simple and reliable voltage balancing technique due to having some redundant switching states. Moreover, a sensor-less voltage balancing technique is designed and implemented on the PUC5 inverter successfully to work in both stand-alone and gridconnected mode of operation. Eventually, a modified configuration of the PUC5 topology is presented to work as a buck PFC rectifier. The internal performance of the rectifier is like a buck converter to generate stepped down DC voltages at the two output terminals while the grid sees a boost converter externally. As well, a decoupled voltage/current controller is designed and applied to balance the output voltages identically and synchronize the input current with grid voltage to have a PFC operation acceptably. A power balance analysis is done to show the load variation range limit. All the theoretical and simulation studies are validated by experimental results completely.
AIRBORNE PARTICLE SIZES AND SOURCES FOUND IN INDOOR AIR

EPA Science Inventory

As concern about indoor air quality (IAQ) has grown in recent years, understanding indoor aerosols has become increasingly important so that control techniques may be implemented to reduce damaging health effects and soiling problems. This paper begins with a brief look at the me...
La conception, la modelisation et la simulation du systeme VSC-HVDC offshore

NASA Astrophysics Data System (ADS)

Benhalima, Seghir

Wind energy is recognized worldwide as a proven technology to meet the growing demands of green sustainable energy. To exploit this stochastic energy source and put together with the conventional energy sources without affecting the performance of existing electrical grids, several research projects have been achieved. In addition, at ocean level, wind energy has a great potential. It means that the production of this energy will increase in the world. The optimal extraction of this energy source needs to be connected to the grid via a voltage source converter which plays the role of interface. To minimise losses due to the transport of energy at very long distances, the technology called High Voltage Direct Current based on Voltage Source Converter (VSC-HVDC) is used. To achieve this goal, a new topology is designed with a new control algorithm based on control of power generated by the wind farm, the DC voltage regulation and the synchronization between wind farm and VSC-HVDC (based on NPC). The proposed topology and its control technique are validated using the "MATLAB/Simulink program". The results are promising, because the THD is less than 5% and the power factor is close to one.
The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source

NASA Astrophysics Data System (ADS)

Yokoyama, K.; Lord, J. S.; Murahari, P.; Wang, K.; Dunstan, D. J.; Waller, S. P.; McPhail, D. J.; Hillier, A. D.; Henson, J.; Harper, M. R.; Heathcote, P.; Drew, A. J.

2016-12-01

A high power pulsed laser system has been installed on the high magnetic field muon spectrometer (HiFi) at the International Science Information Service pulsed neutron and muon source, situated at the STFC Rutherford Appleton Laboratory in the UK. The upgrade enables one to perform light-pump muon-probe experiments under a high magnetic field, which opens new applications of muon spin spectroscopy. In this report we give an overview of the principle of the HiFi laser system and describe the newly developed techniques and devices that enable precisely controlled photoexcitation of samples in the muon instrument. A demonstration experiment illustrates the potential of this unique combination of the photoexcited system and avoided level crossing technique.
The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source.

PubMed

Yokoyama, K; Lord, J S; Murahari, P; Wang, K; Dunstan, D J; Waller, S P; McPhail, D J; Hillier, A D; Henson, J; Harper, M R; Heathcote, P; Drew, A J

2016-12-01

A high power pulsed laser system has been installed on the high magnetic field muon spectrometer (HiFi) at the International Science Information Service pulsed neutron and muon source, situated at the STFC Rutherford Appleton Laboratory in the UK. The upgrade enables one to perform light-pump muon-probe experiments under a high magnetic field, which opens new applications of muon spin spectroscopy. In this report we give an overview of the principle of the HiFi laser system and describe the newly developed techniques and devices that enable precisely controlled photoexcitation of samples in the muon instrument. A demonstration experiment illustrates the potential of this unique combination of the photoexcited system and avoided level crossing technique.
Making AlN(x) Tunnel Barriers Using a Low-Energy Nitrogen-Ion Beam

NASA Technical Reports Server (NTRS)

Kaul, Anupama; Kleinsasser, Alan; Bumble, Bruce; LeDuc, Henry; Lee, Karen

2005-01-01

A technique based on accelerating positive nitrogen ions onto an aluminum layer has been demonstrated to be effective in forming thin (<2 nm thick) layers of aluminum nitride (AlN(x)) for use as tunnel barriers in Nb/Al-AlN(x)/Nb superconductor/insulator/ superconductor (SIS) Josephson junctions. AlN(x) is the present material of choice for tunnel barriers because, to a degree greater than that of any other suitable material, it offers the required combination of low leakage current at high current density and greater thermal stability. While ultra-thin AlN films with good thickness and stoichiometry control are easily formed using techniques such as reactive molecular beam epitaxy and chemical vapor deposition, growth temperatures of 900 C are necessary for the dissociative adsorption of nitrogen from either nitrogen (N2) or ammonia (NH3). These growth temperatures are prohibitively high for the formation of tunnel barriers on Nb films because interfacial reactions at temperatures as low as 200 to 300 C degrade device properties. Heretofore, deposition by reactive sputtering and nitridation of thin Al layers with DC and RF nitrogen plasmas have been successfully used to form AlN barriers in SIS junctions. However, precise control over critical current density Jc has proven to be a challenge, as is attaining adequate process reproducibility from system to system. The present ion-beam technique is an alternative to the plasma or reactive sputtering techniques as it provides a highly controlled arrival of reactive species, independent of the electrical conditions of the substrate or vacuum chamber. Independent and accurate control of parameters such as ion energy, flux, species, and direction promises more precise control of film characteristics such as stoichiometry and thickness than is the case with typical plasma processes. In particular, the background pressure during ion-beam nitride growth is 2 or 3 orders of magnitude lower, minimizing the formation of compounds with contaminants, which is critical in devices the performance of which is dictated by interfacial characteristics. In addition, the flux of incoming species can be measured in situ using ion probes so that the dose can be controlled accurately. The apparatus used in the present ion-beam technique includes a vacuum chamber containing a commercial collimated- ion-beam source, a supply of nitrogen and argon, and an ion probe for measuring the ion dose. Either argon or nitrogen can be used as the feed gases for the ion source, depending on whether cleaning of the substrate or growth of the nitride, respectively, is desired. Once the Nb base electrode and Al proximity layer have been deposited, the N2 gas line to the ion beam is vented and purged, and the ion-source is turned on until a stable discharge is obtained. The substrate is moved over the ion-beam source to expose the Al surface layer to the ion beam (see figure) for a specified duration for the formation of the nitride tunnel barrier. Next, the Nb counter-electrode layer is deposited on the nitride surface layer. The Nb/Al- AlN(x)/Nb-trilayer-covered substrate is then patterned into individual devices by use of conventional integrated-circuit processing techniques.

Controlling Fringe Sensitivity of Electro-Optic Holography Systems Using Laser Diode Current Modulation

NASA Technical Reports Server (NTRS)

Bybee, Shannon J.

2001-01-01

Electro-Optic Holography (EOH) is a non-intrusive, laser-based, displacement measurement technique capable of static and dynamic displacement measurements. EOH is an optical interference technique in which fringe patterns that represent displacement contour maps are generated. At excessively large displacements the fringe density may be so great that individual fringes are not resolvable using typical EOH techniques. This thesis focuses on the development and implementation of a method for controlling the sensitivity of the EOH system. This method is known as Frequency Translated Electro-Optic Holography (FTEOH). It was determined that by modulating the current source of the laser diode at integer multiples of the object vibration, the fringe pattern is governed by higher order Bessel function of the first kind and the number of fringes that represent a given displacement can be controlled. The reduction of fringes is theoretically unlimited but physically limited by the frequency bandwidth of the signal generator, providing modulation to the laser diode. Although this research technique has been verified theoretically and experimentally in this thesis, due to the current laser diode capabilities it is a tedious and time consuming process to acquire data using the FTEOH technique.
High Power Laser Safety

NASA Astrophysics Data System (ADS)

Brusl, Helmut

1986-10-01

The Austrian legislation about laser safety is discussed. Appropriate control measures for laser use and alternate means of enclosure and baffling are presented. Present laser safety standards are explained briefly. Eye protective techniques and eyewear are considered for a variety of sources. The optical properties of enclosure materials are also discussed.
Induction motor control

NASA Technical Reports Server (NTRS)

Hansen, Irving G.

1990-01-01

Electromechanical actuators developed to date have commonly utilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilizes induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high frequency power distribution and management techniques developed by NASA for Space Station Freedom.
Induction motor control

NASA Technical Reports Server (NTRS)

Hansen, Irving G.

1990-01-01

Electromechanical actuators developed to date have commonly ultilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilized induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high-frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high-frequency power distribution and management techniques developed by NASA for Space Station Freedom.
Agent-based power sharing scheme for active hybrid power sources

NASA Astrophysics Data System (ADS)

Jiang, Zhenhua

The active hybridization technique provides an effective approach to combining the best properties of a heterogeneous set of power sources to achieve higher energy density, power density and fuel efficiency. Active hybrid power sources can be used to power hybrid electric vehicles with selected combinations of internal combustion engines, fuel cells, batteries, and/or supercapacitors. They can be deployed in all-electric ships to build a distributed electric power system. They can also be used in a bulk power system to construct an autonomous distributed energy system. An important aspect in designing an active hybrid power source is to find a suitable control strategy that can manage the active power sharing and take advantage of the inherent scalability and robustness benefits of the hybrid system. This paper presents an agent-based power sharing scheme for active hybrid power sources. To demonstrate the effectiveness of the proposed agent-based power sharing scheme, simulation studies are performed for a hybrid power source that can be used in a solar car as the main propulsion power module. Simulation results clearly indicate that the agent-based control framework is effective to coordinate the various energy sources and manage the power/voltage profiles.
Sources of hydrocarbons in urban road dust: Identification, quantification and prediction.

PubMed

Mummullage, Sandya; Egodawatta, Prasanna; Ayoko, Godwin A; Goonetilleke, Ashantha

2016-09-01

Among urban stormwater pollutants, hydrocarbons are a significant environmental concern due to their toxicity and relatively stable chemical structure. This study focused on the identification of hydrocarbon contributing sources to urban road dust and approaches for the quantification of pollutant loads to enhance the design of source control measures. The study confirmed the validity of the use of mathematical techniques of principal component analysis (PCA) and hierarchical cluster analysis (HCA) for source identification and principal component analysis/absolute principal component scores (PCA/APCS) receptor model for pollutant load quantification. Study outcomes identified non-combusted lubrication oils, non-combusted diesel fuels and tyre and asphalt wear as the three most critical urban hydrocarbon sources. The site specific variabilities of contributions from sources were replicated using three mathematical models. The models employed predictor variables of daily traffic volume (DTV), road surface texture depth (TD), slope of the road section (SLP), effective population (EPOP) and effective impervious fraction (EIF), which can be considered as the five governing parameters of pollutant generation, deposition and redistribution. Models were developed such that they can be applicable in determining hydrocarbon contributions from urban sites enabling effective design of source control measures. Copyright © 2016 Elsevier Ltd. All rights reserved.
Optical control of hard X-ray polarization by electron injection in a laser wakefield accelerator

PubMed Central

Schnell, Michael; Sävert, Alexander; Uschmann, Ingo; Reuter, Maria; Nicolai, Maria; Kämpfer, Tino; Landgraf, Björn; Jäckel, Oliver; Jansen, Oliver; Pukhov, Alexander; Kaluza, Malte Christoph; Spielmann, Christian

2013-01-01

Laser-plasma particle accelerators could provide more compact sources of high-energy radiation than conventional accelerators. Moreover, because they deliver radiation in femtosecond pulses, they could improve the time resolution of X-ray absorption techniques. Here we show that we can measure and control the polarization of ultra-short, broad-band keV photon pulses emitted from a laser-plasma-based betatron source. The electron trajectories and hence the polarization of the emitted X-rays are experimentally controlled by the pulse-front tilt of the driving laser pulses. Particle-in-cell simulations show that an asymmetric plasma wave can be driven by a tilted pulse front and a non-symmetric intensity distribution of the focal spot. Both lead to a notable off-axis electron injection followed by collective electron–betatron oscillations. We expect that our method for an all-optical steering is not only useful for plasma-based X-ray sources but also has significance for future laser-based particle accelerators. PMID:24026068
External control of electron energy distributions in a dual tandem inductively coupled plasma

NASA Astrophysics Data System (ADS)

Liu, Lei; Sridhar, Shyam; Zhu, Weiye; Donnelly, Vincent M.; Economou, Demetre J.; Logue, Michael D.; Kushner, Mark J.

2015-08-01

The control of electron energy probability functions (EEPFs) in low pressure partially ionized plasmas is typically accomplished through the format of the applied power. For example, through the use of pulse power, the EEPF can be modulated to produce shapes not possible under continuous wave excitation. This technique uses internal control. In this paper, we discuss a method for external control of EEPFs by transport of electrons between separately powered inductively coupled plasmas (ICPs). The reactor incorporates dual ICP sources (main and auxiliary) in a tandem geometry whose plasma volumes are separated by a grid. The auxiliary ICP is continuously powered while the main ICP is pulsed. Langmuir probe measurements of the EEPFs during the afterglow of the main ICP suggests that transport of hot electrons from the auxiliary plasma provided what is effectively an external source of energetic electrons. The tail of the EEPF and bulk electron temperature were then elevated in the afterglow of the main ICP by this external source of power. Results from a computer simulation for the evolution of the EEPFs concur with measured trends.
Nucleation and convection effects in protein crystal growth

NASA Technical Reports Server (NTRS)

Rosenberger, Franz (Principal Investigator)

1996-01-01

The following activities are reported on: repartitioning of NaCl and protein impurities in lysozyme crystallization; dependence of lysozyme growth kinetics on step sources and impurities; facet morphology response to nonuniformities in nutrient and impurity supply; interactions in undersaturated and supersaturated lysozyme solutions; heterogeneity determination and purification of commercial hen egg white lysozyme; nonlinear response of layer growth dynamics in the mixed kinetics-bulk transport regime; development of a simultaneous multiangle light scattering technique; and x-ray topography of tetragonal lysozyme grown by the temperature-control technique.
77 FR 28336 - Approval and Promulgation of Air Quality Implementation Plans; Maryland; Offset Lithographic...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-14

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Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-23

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Optical tools and techniques for aligning solar payloads with the SPARCS control system. [Solar Pointing Aerobee Rocket Control System

NASA Technical Reports Server (NTRS)

Thomas, N. L.; Chisel, D. M.

1976-01-01

The success of a rocket-borne experiment depends not only on the pointing of the attitude control system, but on the alignment of the attitude control system to the payload. To ensure proper alignment, special optical tools and alignment techniques are required. Those that were used in the SPARCS program are described and discussed herein. These tools include theodolites, autocollimators, a 38-cm diameter solar simulator, a high-performance 1-m heliostat to provide a stable solar source during the integration of the rocket payload, a portable 75-cm sun tracker for use at the launch site, and an innovation called the Solar Alignment Prism. Using the real sun as the primary reference under field conditions, the Solar Alignment Prism facilitates the coalignment of the attitude sun sensor with the payload. The alignment techniques were developed to ensure the precise alignment of the solar payloads to the SPARCS attitude sensors during payload integration and to verify the required alignment under field conditions just prior to launch.
Tracing nitrates and sulphates in river basins using isotope techniques.

PubMed

Rock, L; Mayer, B

2006-01-01

The objective of this paper is to outline how stable isotope techniques can contribute to the elucidation of the sources and the fate of riverine nitrate and sulphate in watershed studies. The example used is the Oldman River Basin (OMRB), located in southern Alberta (Canada). Increasing sulphate concentrations and decreasing delta(34)S values along the flowpath of the Oldman River indicate that oxidation of pyrite in tills is a major source of riverine sulphate in the agriculturally used portion of the OMRB. Chemical and isotopic data showed that manure-derived nitrogen contributes significantly to the increase in nitrate concentrations in the Oldman River and its tributaries draining agricultural land. It is suggested that hydrological conditions control agricultural return flows to the surface water bodies in southern Alberta and impart significant seasonal variations on concentrations and isotopic compositions of riverine nitrate. Combining isotopic, chemical, and hydrometric data permitted us to estimate the relative contribution of major sources to the total solute fluxes. Hence, we submit that isotopic measurements can make an important contribution to the identification of nutrient and pollutant sources and to river basin management.
Common method biases in behavioral research: a critical review of the literature and recommended remedies.

PubMed

Podsakoff, Philip M; MacKenzie, Scott B; Lee, Jeong-Yeon; Podsakoff, Nathan P

2003-10-01

Interest in the problem of method biases has a long history in the behavioral sciences. Despite this, a comprehensive summary of the potential sources of method biases and how to control for them does not exist. Therefore, the purpose of this article is to examine the extent to which method biases influence behavioral research results, identify potential sources of method biases, discuss the cognitive processes through which method biases influence responses to measures, evaluate the many different procedural and statistical techniques that can be used to control method biases, and provide recommendations for how to select appropriate procedural and statistical remedies for different types of research settings.
High-power femtosecond pulses without a modelocked laser

PubMed Central

Fu, Walter; Wright, Logan G.; Wise, Frank W.

2017-01-01

We demonstrate a fiber system which amplifies and compresses pulses from a gain-switched diode. A Mamyshev regenerator shortens the pulses and improves their coherence, enabling subsequent amplification by parabolic pre-shaping. As a result, we are able to control nonlinear effects and generate nearly transform-limited, 140-fs pulses with 13-MW peak power—an order-of-magnitude improvement over previous gain-switched diode sources. Seeding with a gain-switched diode results in random fluctuations of 2% in the pulse energy, which future work using known techniques may ameliorate. Further development may allow such systems to compete directly with sources based on modelocked oscillators in some applications while enjoying unparalleled robustness and repetition rate control. PMID:29214187
A linearly controlled direct-current power source for high-current inductive loads in a magnetic suspension wind tunnel

NASA Technical Reports Server (NTRS)

Tripp, John S.; Daniels, Taumi S.

1990-01-01

The NASA Langley 6 inch magnetic suspension and balance system (MSBS) requires an independently controlled bidirectional DC power source for each of six positioning electromagnets. These electromagnets provide five-degree-of-freedom control over a suspended aerodynamic test model. Existing power equipment, which employs resistance coupled thyratron controlled rectifiers as well as AC to DC motor generator converters, is obsolete, inefficient, and unreliable. A replacement six phase bidirectional controlled bridge rectifier is proposed, which employs power MOSFET switches sequenced by hybrid analog/digital circuits. Full load efficiency is 80 percent compared to 25 percent for the resistance coupled thyratron system. Current feedback provides high control linearity, adjustable current limiting, and current overload protection. A quenching circuit suppresses inductive voltage impulses. It is shown that 20 kHz interference from positioning magnet power into MSBS electromagnetic model position sensors results predominantly from capacitively coupled electric fields. Hence, proper shielding and grounding techniques are necessary. Inductively coupled magnetic interference is negligible.
[Strengthening the control of goat schistosomiasis to facilitate the progress towards elimination of schistosomiasis in China].

PubMed

Jiao-Jiao, Lin

2016-10-20

Although great success has been achieved in schistosomiasis control, schistosomiasis japonica remains a publichealth concern in China. Schistosoma japonicum is found to naturally infect over 40 mammalian animals. The implementation of the integrated schistosomiasis control strategy emphasizing infectious source control since 2004, which integrates replacement of bovines with machines, breeding domestic animals in fences, building safe pastures and chemotherapy of infected bovines, results in a clear-cut reduction in the prevalence of S. japonicum infection in both humans and bovines, as well as the areas of infected snail habitats, and the national schistosomiasis control program is moving from transmission control towards transmission interruption and elimination. It has been found that goat is highly susceptible to S. japonicum infection, and previous epidemiological data have shown a high prevalence of infection in goat. However, the role of goat in the transmission of schistosomiasis japonica has not been paid much attention, and there are few systematic surveys to evaluate the role of goat in schistosomiasis transmission in China to date. Professor Liang Yousheng's group investigated S. japonicum development and reproduction (egglaying) in goat body, environmental contamination by goat feces, and the effect of temperature and humidity on the survival of S. japonicum eggs in goat feces. Their findings further demonstrate the role of goat in the transmission of schistosomiasis japonica. In addition, they proposed, based on their findings and previous reports, that the management of goat should be integrated into the national schistosomiasis control program in China, since goat is virtually one of the major infectious sources of schistosomiasis japonica in China. Moreover, this group improved the fecal hatching test and optimized the parasitological technique for diagnosis of S. japonicum infection in goats. These innovative studies fill in the gaps of goat schitsosomiasis japonica research in China, and the research outcomes will enrich the currently implemented integrated schistosomiasis control strategy emphasizing infectious source control, and are believed to play a critical role in schistosomiasis elimination in China. Since schistosomiasis seriously affects goat husbandry development and local famer income, and goat has become a major infectious source of schistosomiasis japonica in China, the control of goat schistosomiaiss will facilitate the progress towards the elimination of schistosomiasis in China, and the following research priorities are suggested: (1) to emphasize the control of goat schistosomiasis, and to integrate the comprehensive management of goat into the national schistosomiasis control program in China; and (2) to develop new techniques, products and interventions for the control of goat schistosomiasis.
Obsessive-compulsive dimension localized using low-resolution brain electromagnetic tomography (LORETA).

PubMed

Sherlin, Leslie; Congedo, Marco

2005-10-21

Electroencephalographic mapping techniques have been used to show differences between normal subjects and those diagnosed with various mental disorders. To date, there is no other research using the techniques of low-resolution brain electromagnetic tomography (LORETA) with the obsessive-compulsive disorder (OCD) population. The current investigation compares current source density measures of persons with OCD symptoms to an age-matched control group. The main finding is excess current source density in the Beta frequencies in the cingulate gyrus. This Beta activity is primarily located in the middle cingulate gyrus as well as adjacent frontal parieto-occipital regions. Lower frequency Beta is prominent more anteriorly in the cingulate gyrus whereas higher frequency Beta is seen more posteriorly. These preliminary findings indicate the utility of LORETA as a clinical and diagnostic tool.
Coherent Bragg nanodiffraction at the hard X-ray Nanoprobe beamline.

PubMed

Hruszkewycz, S O; Holt, M V; Maser, J; Murray, C E; Highland, M J; Folkman, C M; Fuoss, P H

2014-03-06

Bragg coherent diffraction with nanofocused hard X-ray beams provides unique opportunities for quantitative in situ studies of crystalline structure in nanoscale regions of complex materials and devices by a variety of diffraction-based techniques. In the case of coherent diffraction imaging, a major experimental challenge in using nanoscale coherent beams is maintaining a constant scattering volume such that coherent fringe visibility is maximized and maintained over the course of an exposure lasting several seconds. Here, we present coherent Bragg diffraction patterns measured from different nanostructured thin films at the Sector 26 Nanoprobe beamline at the Advanced Photon Source and demonstrate that with nanoscale positional control, coherent diffraction patterns can be measured with source-limited fringe visibilities more than 50% suitable for imaging by coherent Bragg ptychography techniques.
Coherent Bragg nanodiffraction at the hard X-ray Nanoprobe beamline

PubMed Central

Hruszkewycz, S. O.; Holt, M. V.; Maser, J.; Murray, C. E.; Highland, M. J.; Folkman, C. M.; Fuoss, P. H.

2014-01-01

Bragg coherent diffraction with nanofocused hard X-ray beams provides unique opportunities for quantitative in situ studies of crystalline structure in nanoscale regions of complex materials and devices by a variety of diffraction-based techniques. In the case of coherent diffraction imaging, a major experimental challenge in using nanoscale coherent beams is maintaining a constant scattering volume such that coherent fringe visibility is maximized and maintained over the course of an exposure lasting several seconds. Here, we present coherent Bragg diffraction patterns measured from different nanostructured thin films at the Sector 26 Nanoprobe beamline at the Advanced Photon Source and demonstrate that with nanoscale positional control, coherent diffraction patterns can be measured with source-limited fringe visibilities more than 50% suitable for imaging by coherent Bragg ptychography techniques. PMID:24470418

A technique to control cross-field diffusion of plasma across a transverse magnetic field

NASA Astrophysics Data System (ADS)

Hazarika, P.; Chakraborty, M.; Das, B. K.; Bandyopadhyay, M.

2016-12-01

A study to control charged particle transport across a transverse magnetic field (TMF), popularly known as the magnetic filter in a negative ion source, has been carried out in a double plasma device. In the experimental setup, the TMF placed between the two magnetic cages divides the whole plasma chamber into two distinct regions, viz., the source and the target on the basis of the plasma production and the corresponding electron temperature. The plasma produced in the source region by the filament discharge method diffuses into the target region through the TMF. Data are acquired by the Langmuir probe and are compared in different source configurations, in terms of external biasing applied to metallic plates inserted in the TMF plane but in the orthogonal direction. The effect of the direction of current between the two plates in either polarity of bias in the presence of TMF on the plasma parameters and the cross-field transport of charge particles are discussed.
Etching radical controlled gas chopped deep reactive ion etching

DOEpatents

Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

2013-10-01

A method for silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping has been developed capable of producing essentially scallop-free, smooth, sidewall surfaces. The method uses precisely controlled, alternated (or chopped) gas flow of the etching and deposition gas precursors to produce a controllable sidewall passivation capable of high anisotropy. The dynamic control of sidewall passivation is achieved by carefully controlling fluorine radical presence with moderator gasses, such as CH.sub.4 and controlling the passivation rate and stoichiometry using a CF.sub.2 source. In this manner, sidewall polymer deposition thicknesses are very well controlled, reducing sidewall ripples to very small levels. By combining inductively coupled plasmas with controlled fluorocarbon chemistry, good control of vertical structures with very low sidewall roughness may be produced. Results show silicon features with an aspect ratio of 20:1 for 10 nm features with applicability to nano-applications in the sub-50 nm regime. By comparison, previous traditional gas chopping techniques have produced rippled or scalloped sidewalls in a range of 50 to 100 nm roughness.
Development of a complex experimental system for controlled ecological life support technique

NASA Astrophysics Data System (ADS)

Guo, S.; Tang, Y.; Zhu, J.; Wang, X.; Feng, H.; Ai, W.; Qin, L.; Deng, Y.

A complex experimental system for controlled ecological life support technique can be used as a test platform for plant-man integrated experiments and material close-loop experiments of the controlled ecological life support system CELSS Based on lots of plan investigation plan design and drawing design the system was built through the steps of processing installation and joined debugging The system contains a volume of about 40 0m 3 its interior atmospheric parameters such as temperature relative humidity oxygen concentration carbon dioxide concentration total pressure lighting intensity photoperiod water content in the growing-matrix and ethylene concentration are all monitored and controlled automatically and effectively Its growing system consists of two rows of racks along its left-and-right sides separately and each of which holds two up-and-down layers eight growing beds hold a total area of about 8 4m 2 and their vertical distance can be adjusted automatically and independently lighting sources consist of both red and blue light-emitting diodes Successful development of the test platform will necessarily create an essential condition for next large-scale integrated study of controlled ecological life support technique
Robust terahertz self-heterodyne system using a phase noise compensation technique.

PubMed

Song, Hajun; Song, Jong-In

2015-08-10

We propose and demonstrate a robust terahertz self-heterodyne system using a phase noise compensation technique. Conventional terahertz self-heterodyne systems suffer from degraded phase noise performance due to phase noise of the laser sources. The proposed phase noise compensation technique uses an additional photodiode and a simple electric circuit to produce phase noise identical to that observed in the terahertz signal produced by the self-heterodyne system. The phase noise is subsequently subtracted from the terahertz signal produced by the self-heterodyne system using a lock-in amplifier. While the terahertz self-heterodyne system using a phase noise compensation technique offers improved phase noise performance, it also provides a reduced phase drift against ambient temperature variations. The terahertz self-heterodyne system using a phase noise compensation technique shows a phase noise of 0.67 degree in terms of a standard deviation value even without using overall delay balance control. It also shows a phase drift of as small as approximately 10 degrees in an open-to-air measurement condition without any strict temperature control.
Power System Analysis

NASA Astrophysics Data System (ADS)

Taniguchi, Haruhito

Electric power generation that relies on various sources as the primary sources of energy is expected to bring down CO2 emissions levels to support the overall strategy to curb global warming. Accordingly, utilities are moving towards integrating more renewable sources for generation, mostly dispersed, and adopting Smart Grid Technologies for system control. In order to construct, operate, and maintain power systems stably and economically in such background, thorough understanding about the characteristics of power systems and their components is essential. This paper presents modeling and simulation techniques available for the analysis of critical aspects such as thermal capacity, stability, voltage stability, and frequency dynamics, vital for the stable operation of power systems.
Adaptive Environmental Source Localization and Tracking with Unknown Permittivity and Path Loss Coefficients †

PubMed Central

Fidan, Barış; Umay, Ilknur

2015-01-01

Accurate signal-source and signal-reflector target localization tasks via mobile sensory units and wireless sensor networks (WSNs), including those for environmental monitoring via sensory UAVs, require precise knowledge of specific signal propagation properties of the environment, which are permittivity and path loss coefficients for the electromagnetic signal case. Thus, accurate estimation of these coefficients has significant importance for the accuracy of location estimates. In this paper, we propose a geometric cooperative technique to instantaneously estimate such coefficients, with details provided for received signal strength (RSS) and time-of-flight (TOF)-based range sensors. The proposed technique is integrated to a recursive least squares (RLS)-based adaptive localization scheme and an adaptive motion control law, to construct adaptive target localization and adaptive target tracking algorithms, respectively, that are robust to uncertainties in aforementioned environmental signal propagation coefficients. The efficiency of the proposed adaptive localization and tracking techniques are both mathematically analysed and verified via simulation experiments. PMID:26690441
DOE Office of Scientific and Technical Information (OSTI.GOV)

Mukamel, Shaul, E-mail: smukamel@uci.edu; Bakker, Huib J.

Multidimensional signals are generated by subjecting molecules to sequences of short optical pulses and recording correlation plots related to the various controlled delay periods. These techniques which span all the way from the THz to the x-ray regimes provide qualitatively new structural and dynamical molecular information not available from conventional one-dimensional techniques. This issue surveys the recent experimental and theoretical progresses in this rapidly developing 20 year old field which illustrates the novel insights provided by multidimensional techniques into electronic and nuclear motions. It should serve as a valuable source for experts in the field and help introduce newcomers tomore » this exciting and challenging branch of nonlinear spectroscopy.« less
Detection of active noise control on the standard motorcycle exhaust Supra X 125 D using PVC pipe technique form Y

NASA Astrophysics Data System (ADS)

Isranuri, I.; Alfisyahrin; Nasution, A. R.

2018-02-01

This detection aims to obtain noise reduction on the supra X 125D motorcycle exhaust by using the Active Noise Control Method. The technique is done using a Y-shaped PVC pipe to be bolted on the exhaust, which then branch Y PVC is placed loudspeaker with impermeable conditions. The function of this loudspeaker is as a secondary noise to counter the primary noise of the sound of exhaust motorcycle Supra X 125D. The sound generator in this study is the ISD 4004 module, which serves to generate noise to counter the source noise. How this ISD 4004 module works is by recording source noise then recording the source noise and then reversed the phase 180° by phase reversing circuit. So that, the noise generated by the sound generator will hit the source noise and encounter or such as addition of two different phase of sound will result in noise reduction when detected at the end of the Y-shaped PVC pipe. Inverted phase reversed using feed-back resistor 1 kΩ and 2 kΩ input resistors, 16V capacitor 2500μf and as amplifier using ICL 7660 and TL 702 CP. Test results on the highest 1000 rpm rotation engine speed on the Z axis of 2 dB, and at the highest 2000 rpm rotation engine speed also occurs on the Z axis of 1.5 dB.
DC Microgrids–Part I: A Review of Control Strategies and Stabilization Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dragicevic, Tomislav; Lu, Xiaonan; Vasquez, Juan

2015-01-01

This paper presents a review of control strategies, stability analysis, and stabilization techniques for dc microgrids (MGs). Overall control is systematically classified into local and coordinated control levels according to respective functionalities in each level. As opposed to local control, which relies only on local measurements, some line of communication between units needs to be made available in order to achieve the coordinated control. Depending on the communication method, three basic coordinated control strategies can be distinguished, i.e., decentralized, centralized, and distributed control. Decentralized control can be regarded as an extension of the local control since it is also basedmore » exclusively on local measurements. In contrast, centralized and distributed control strategies rely on digital communication technologies. A number of approaches using these three coordinated control strategies to achieve various control objectives are reviewed in this paper. Moreover, properties of dc MG dynamics and stability are discussed. This paper illustrates that tightly regulated point-of-load converters tend to reduce the stability margins of the system since they introduce negative impedances, which can potentially oscillate with lightly damped power supply input filters. It is also demonstrated that how the stability of the whole system is defined by the relationship of the source and load impedances, referred to as the minor loop gain. Several prominent specifications for the minor loop gain are reviewed. Finally, a number of active stabilization techniques are presented.« less
Generating High-Brightness Ion Beams for Inertial Confinement Fusion

NASA Astrophysics Data System (ADS)

Cuneo, M. E.

1997-11-01

The generation of high current density ion beams with applied-B ion diodes showed promise in the late-1980's as an efficient, rep-rate, focusable driver for inertial confinement fusion. These devices use several Tesla insulating magnetic fields to restrict electron motion across anode-cathode gaps of order 1-2 cm, while accelerating ions to generate ≈ 1 kA/cm^2, 5 - 15 MeV beams. These beams have been used to heat hohlraums to about 65 eV. However, meeting the ICF driver requirements for low-divergence and high-brightness lithium ion beams has been more technically challenging than initially thought. Experimental and theoretical work over the last 5 years shows that high-brightness beams meeting the requirements for inertial confinement fusion are possible. The production of these beams requires the simultaneous integration of at least four conditions: 1) rigorous vacuum cleaning techniques for control of undesired anode, cathode, ion source and limiter plasma formation from electrode contaminants to control impurity ions and impedance collapse; 2) carefully tailored insulating magnetic field geometry for uniform beam generation; 3) high magnetic fields (V_crit/V > 2) and other techniques to control the electron sheath and the onset of a high divergence electromagnetic instability that couples strongly to the ion beam; and 4) an active, pre-formed, uniform lithium plasma for low source divergence which is compatible with the above electron-sheath control techniques. These four conditions have never been simultaneously present in any lithium beam experiment, but simulations and experimental tests of individual conditions have been done. The integration of these conditions is a goal of the present ion beam generation program at Sandia. This talk will focus on the vacuum cleaning techniques for ion diodes and pulsed power devices in general, including experimental results obtained on the SABRE and PBFA-II accelerators over the last 3 years. The current status of integration of the other key physics and technologies required to demonstrate high-brightness ion beams will also be presented.
Numerical Analysis of the Cavity Flow subjected to Passive Controls Techniques

NASA Astrophysics Data System (ADS)

Melih Guleren, Kursad; Turk, Seyfettin; Mirza Demircan, Osman; Demir, Oguzhan

2018-03-01

Open-source flow solvers are getting more and more popular for the analysis of challenging flow problems in aeronautical and mechanical engineering applications. They are offered under the GNU General Public License and can be run, examined, shared and modified according to user’s requirements. SU2 and OpenFOAM are the two most popular open-source solvers in Computational Fluid Dynamics (CFD) community. In the present study, some passive control methods on the high-speed cavity flows are numerically simulated using these open-source flow solvers along with one commercial flow solver called ANSYS/Fluent. The results are compared with the available experimental data. The solver SU2 are seen to predict satisfactory the mean streamline velocity but not turbulent kinetic energy and overall averaged sound pressure level (OASPL). Whereas OpenFOAM predicts all these parameters nearly as the same levels of ANSYS/Fluent.
Reporting the accuracy of biochemical measurements for epidemiologic and nutrition studies.

PubMed

McShane, L M; Clark, L C; Combs, G F; Turnbull, B W

1991-06-01

Procedures for reporting and monitoring the accuracy of biochemical measurements are presented. They are proposed as standard reporting procedures for laboratory assays for epidemiologic and clinical-nutrition studies. The recommended procedures require identification and estimation of all major sources of variability and explanations of laboratory quality control procedures employed. Variance-components techniques are used to model the total variability and calculate a maximum percent error that provides an easily understandable measure of laboratory precision accounting for all sources of variability. This avoids ambiguities encountered when reporting an SD that may taken into account only a few of the potential sources of variability. Other proposed uses of the total-variability model include estimating precision of laboratory methods for various replication schemes and developing effective quality control-checking schemes. These procedures are demonstrated with an example of the analysis of alpha-tocopherol in human plasma by using high-performance liquid chromatography.
In-situ x-ray studies of compositional control during synthesis of LaGaO 3 by radio frequency-magnetron sputtering

DOE PAGES

Highland, Matthew J.; Fong, Dillon D.; Ju, Guangxu; ...

2015-08-28

In-situ synchrotron x-ray scattering has been used to monitor and control the synthesis of LaGaO 3 epitaxial thin films by 90° off-axis RF-magnetron sputtering. We compared films deposited from a single LaGaO 3 source with those prepared by alternating deposition from separate La 2O 3 and Ga 2O 3 sources. The conditions for growth of stoichiometric films were determined by real-time monitoring of secondary phase formation as well as from features in the diffuse scatter from island formation during synthesis. Our results provide atomic-scale insight into the mechanisms taking place during reactive epitaxial growth and demonstrate how in-situ techniques canmore » be utilized to achieve stoichiometric control in ultrathin films.« less
A high accuracy sequential solver for simulation and active control of a longitudinal combustion instability

NASA Technical Reports Server (NTRS)

Shyy, W.; Thakur, S.; Udaykumar, H. S.

1993-01-01

A high accuracy convection scheme using a sequential solution technique has been developed and applied to simulate the longitudinal combustion instability and its active control. The scheme has been devised in the spirit of the Total Variation Diminishing (TVD) concept with special source term treatment. Due to the substantial heat release effect, a clear delineation of the key elements employed by the scheme, i.e., the adjustable damping factor and the source term treatment has been made. By comparing with the first-order upwind scheme previously utilized, the present results exhibit less damping and are free from spurious oscillations, offering improved quantitative accuracy while confirming the spectral analysis reported earlier. A simple feedback type of active control has been found to be capable of enhancing or attenuating the magnitude of the combustion instability.
Nonlinear adaptive control of grid-connected three-phase inverters for renewable energy applications

NASA Astrophysics Data System (ADS)

Mahdian-Dehkordi, N.; Namvar, M.; Karimi, H.; Piya, P.; Karimi-Ghartemani, M.

2017-01-01

Distributed generation (DG) units are often interfaced to the main grid using power electronic converters including voltage-source converters (VSCs). A VSC offers dc/ac power conversion, high controllability, and fast dynamic response. Because of nonlinearities, uncertainties, and system parameters' changes involved in the nature of a grid-connected renewable DG system, conventional linear control methods cannot completely and efficiently address all control objectives. In this paper, a nonlinear adaptive control scheme based on adaptive backstepping strategy is presented to control the operation of a grid-connected renewable DG unit. As compared to the popular vector control technique, the proposed controller offers smoother transient responses, and lower level of current distortions. The Lyapunov approach is used to establish global asymptotic stability of the proposed control system. Linearisation technique is employed to develop guidelines for parameters tuning of the controller. Extensive time-domain digital simulations are performed and presented to verify the performance of the proposed controller when employed in a VSC to control the operation of a two-stage DG unit and also that of a single-stage solar photovoltaic system. Desirable and superior performance of the proposed controller is observed.
Fabrication of selective-area growth InGaN LED by mixed-source hydride vapor-phase epitaxy

NASA Astrophysics Data System (ADS)

Bae, Sung Geun; Jeon, Injun; Jeon, Hunsoo; Kim, Kyoung Hwa; Yang, Min; Yi, Sam Nyung; Lee, Jae Hak; Ahn, Hyung Soo; Yu, Young Moon; Sawaki, Nobuhiko; Kim, Suck-Whan

2018-01-01

We prepared InGaN light-emitting diodes (LEDs) with the active layers grown from a mixed source of Ga-In-N materials on an n-type GaN substrate by a selective-area growth method and three fabrication steps: photolithography, epitaxial layer growth, and metallization. The preparation followed a previously developed experimental process using apparatus for mixed-source hydride vapor-phase epitaxy (HVPE), which consisted of a multi-graphite boat, for insulating against the high temperature and to control the growth rate of epilayers, filled with the mixed source on the inside and a radio-frequency (RF) heating coil for heating to a high temperature (T > 900 °C) and for easy control of temperature outside the source zone. Two types of LEDs were prepared, with In compositions of 11.0 and 6.0% in the InGaN active layer, and room-temperature electroluminescence measurements exhibited a main peak corresponding to the In composition at either 420 or 390 nm. The consecutive growth of InGaN LEDs by the mixed-source HVPE method provides a technique for the production of LEDs with a wide range of In compositions in the active layer.
Inter-noise 89 - Engineering for environmental noise control; Proceedings of the International Conference on Noise Control Engineering, Newport Beach, CA, Dec. 4-6, 1989. Vols. 1 & 2

NASA Astrophysics Data System (ADS)

Maling, George C., Jr.

Recent advances in noise analysis and control theory and technology are discussed in reviews and reports. Topics addressed include noise generation; sound-wave propagation; noise control by external treatments; vibration and shock generation, transmission, isolation, and reduction; multiple sources and paths of environmental noise; noise perception and the physiological and psychological effects of noise; instrumentation, signal processing, and analysis techniques; and noise standards and legal aspects. Diagrams, drawings, graphs, photographs, and tables of numerical data are provided.
Anaerobic soil disinfestation: Carbon rate effects on tomato plant growth and organic acid production

USDA-ARS?s Scientific Manuscript database

Anaerobic soil disinfestation (ASD) is a non-chemical soil disinfestation technique proposed for the control of soil-borne pathogens, plant parasitic-nematodes, and weeds in different crops. ASD is applied in three steps: 1) Soil amendment with a labile carbon (C) source; 2) Cover the soil with tota...
40 CFR Appendix W to Part 51 - Guideline on Air Quality Models

Code of Federal Regulations, 2011 CFR

2011-07-01

... sufficient spatial and temporal coverage are available. c. It would be advantageous to categorize the various... control strategies. These are referred to as refined models. c. The use of screening techniques followed... location of the source in question and its expected impacts. c. In all regulatory analyses, especially if...
A Public-Use, Full-Screen Interface for SPIRES Databases.

ERIC Educational Resources Information Center

Kriz, Harry M.

This paper describes the techniques for implementing a full-screen, custom SPIRES interface for a public-use library database. The database-independent protocol that controls the system is described in detail. Source code for an entire working application using this interface is included. The protocol, with less than 170 lines of procedural code,…

New technology recipes include horseradish, vinegar, mushrooms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishop, J.

1995-08-01

Technology development for more effective environmental management continues to abound. This article contains some recent innovations in the following areas: wastewater treatment; site remediation; and air pollution control. In addition several emerging technologies address solid and hazardous waste management with techniques designed to reduce waste volume, recycle valuable materials and create new energy sources.
Use of artificial landscapes to isolate controls on burn probability

Treesearch

Marc-Andre Parisien; Carol Miller; Alan A. Ager; Mark A. Finney

2010-01-01

Techniques for modeling burn probability (BP) combine the stochastic components of fire regimes (ignitions and weather) with sophisticated fire growth algorithms to produce high-resolution spatial estimates of the relative likelihood of burning. Despite the numerous investigations of fire patterns from either observed or simulated sources, the specific influence of...
PI and fuzzy logic controllers for shunt Active Power Filter--a report.

PubMed

P, Karuppanan; Mahapatra, Kamala Kanta

2012-01-01

This paper presents a shunt Active Power Filter (APF) for power quality improvements in terms of harmonics and reactive power compensation in the distribution network. The compensation process is based only on source current extraction that reduces the number of sensors as well as its complexity. A Proportional Integral (PI) or Fuzzy Logic Controller (FLC) is used to extract the required reference current from the distorted line-current, and this controls the DC-side capacitor voltage of the inverter. The shunt APF is implemented with PWM-current controlled Voltage Source Inverter (VSI) and the switching patterns are generated through a novel Adaptive-Fuzzy Hysteresis Current Controller (A-F-HCC). The proposed adaptive-fuzzy-HCC is compared with fixed-HCC and adaptive-HCC techniques and the superior features of this novel approach are established. The FLC based shunt APF system is validated through extensive simulation for diode-rectifier/R-L loads. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.
Cancelation and its simulation using Matlab according to active noise control case study of automotive noise silencer

NASA Astrophysics Data System (ADS)

Alfisyahrin; Isranuri, I.

2018-02-01

Active Noise Control is a technique to overcome noisy with noise or sound countered with sound in scientific terminology i.e signal countered with signals. This technique can be used to dampen relevant noise in accordance with the wishes of the engineering task and reducing automotive muffler noise to a minimum. Objective of this study is to develop a Active Noise Control which should cancel the noise of automotive Exhaust (Silencer) through Signal Processing Simulation methods. Noise generator of Active Noise Control is to make the opponent signal amplitude and frequency of the automotive noise. The steps are: Firstly, the noise of automotive silencer was measured to characterize the automotive noise that its amplitude and frequency which intended to be expressed. The opposed sound which having similar character with the signal source should be generated by signal function. A comparison between the data which has been completed with simulation calculations Fourier transform field data is data that has been captured on the muffler (noise silencer) Toyota Kijang Capsule assembly 2009. MATLAB is used to simulate how the signal processing noise generated by exhaust (silencer) using FFT. This opponent is inverted phase signal from the signal source 180° conducted by Instruments of Signal Noise Generators. The process of noise cancelation examined through simulation using computer software simulation. The result is obtained that attenuation of sound (noise cancellation) has a difference of 33.7%. This value is obtained from the comparison of the value of the signal source and the signal value of the opponent. So it can be concluded that the noisy signal can be attenuated by 33.7%.
SEM-EDX analysis in the source apportionment of particulate matter on Hypogymnia physodes lichen transplants around the Cu smelter and former mining town of Karabash, South Urals, Russia.

PubMed

Williamson, B J; Mikhailova, I; Purvis, O W; Udachin, V

2004-04-25

Scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX) of particulate matter on lichen transplant thalli (Hypogymnia physodes) was assessed as a complementary technique to wet chemical analysis for source apportionment of airborne contaminants. Transplants (2 month exposure) stationed in the Cu smelter and former mining town of Karabash were compared with those from a control site 30 km south. Particulate matter in Karabash samples (715 analyses) showed higher levels of S, Pb, Cu, Sn and Zn compared with the control (598 analyses). Complex element associations among the particles confounded detailed mineralogical identifications, and therefore a simplified particle classification scheme was devised for source apportionment. Karabash samples contained high levels of particles classified as mining-related (MRP), and these were also identified in control samples, indicating wide spatial dispersion from the smelter and highlighting the sensitivity of the method. It was noted that MRP <2.5-microm diameter were poorly represented on lichen surfaces suggesting this may limit the usefulness of Hypogymnia transplants as proxies when assessing human health impacts from airborne particulates. Analyses of the lichen thallus surface (away from surface particulates) revealed high levels of Cu, Zn, Fe and Pb associated with organics in the Karabash samples compared with the control, with a proportionate loss of K, interpreted as being due to a stress-related increase in cell membrane permeability. This type of analysis may provide a novel SEM-EDX-based method for assessing lichen vitality. The techniques developed are presented and further implications of the study are discussed.
Advanced controls for light sources

NASA Astrophysics Data System (ADS)

Biedron, S. G.; Edelen, A. L.; Milton, S. V.

2016-09-01

We present a summary of our team's recent efforts in developing adaptive, artificial intelligence-inspired techniques specifically to address several control challenges that arise in machines/systems including those in particle accelerator systems. These techniques can readily be adapted to other systems such as lasers, beamline optics, etc… We are not at all suggesting that we create an autonomous system, but create a system with an intelligent control system, that can continually use operational data to improve itself and combines both traditional and advanced techniques. We believe that the system performance and reliability can be increased based on our findings. Another related point is that the controls sub-system of an overall system is usually not the heart of the system architecture or design process. More bluntly, often times all of the peripheral systems are considered as secondary to the main system components in the architecture design process because it is assumed that the controls system will be able to "fix" challenges found later with the sub-systems for overall system operation. We will show that this is not always the case and that it took an intelligent control application to overcome a sub-system's challenges. We will provide a recent example of such a "fix" with a standard controller and with an artificial intelligence-inspired controller. A final related point to be covered is that of system adaptation for requirements not original to a system's original design.
Turbomachinery noise

NASA Astrophysics Data System (ADS)

Groeneweg, John F.; Sofrin, Thomas G.; Rice, Edward J.; Gliebe, Phillip R.

1991-08-01

Summarized here are key advances in experimental techniques and theoretical applications which point the way to a broad understanding and control of turbomachinery noise. On the experimental side, the development of effective inflow control techniques makes it possible to conduct, in ground based facilities, definitive experiments in internally controlled blade row interactions. Results can now be valid indicators of flight behavior and can provide a firm base for comparison with analytical results. Inflow control coupled with detailed diagnostic tools such as blade pressure measurements can be used to uncover the more subtle mechanisms such as rotor strut interaction, which can set tone levels for some engine configurations. Initial mappings of rotor wake-vortex flow fields have provided a data base for a first generation semiempirical flow disturbance model. Laser velocimetry offers a nonintrusive method for validating and improving the model. Digital data systems and signal processing algorithms are bringing mode measurement closer to a working tool that can be frequently applied to a real machine such as a turbofan engine. On the analytical side, models of most of the links in the chain from turbomachine blade source to far field observation point have been formulated. Three dimensional lifting surface theory for blade rows, including source noncompactness and cascade effects, blade row transmission models incorporating mode and frequency scattering, and modal radiation calculations, including hybrid numerical-analytical approaches, are tools which await further application.
Evaluating agricultural nonpoint-source pollution using integrated geographic information systems and hydrologic/water quality model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tim, U.S.; Jolly, R.

1994-01-01

Considerable progress has been made in developing physically based, distributed parameter, hydrologic/water quality (HIWQ) models for planning and control of nonpoint-source pollution. The widespread use of these models is often constrained by the excessive and time-consuming input data demands and the lack of computing efficiencies necessary for iterative simulation of alternative management strategies. Recent developments in geographic information systems (GIS) provide techniques for handling large amounts of spatial data for modeling nonpoint-source pollution problems. Because a GIS can be used to combine information from several sources to form an array of model input data and to examine any combinations ofmore » spatial input/output data, it represents a highly effective tool for HiWQ modeling. This paper describes the integration of a distributed-parameter model (AGNPS) with a GIS (ARC/INFO) to examine nonpoint sources of pollution in an agricultural watershed. The ARC/INFO GIS provided the tools to generate and spatially organize the disparate data to support modeling, while the AGNPS model was used to predict several water quality variables including soil erosion and sedimentation within a watershed. The integrated system was used to evaluate the effectiveness of several alternative management strategies in reducing sediment pollution in a 417-ha watershed located in southern Iowa. The implementation of vegetative filter strips and contour buffer (grass) strips resulted in a 41 and 47% reduction in sediment yield at the watershed outlet, respectively. In addition, when the integrated system was used, the combination of the above management strategies resulted in a 71% reduction in sediment yield. In general, the study demonstrated the utility of integrating a simulation model with GIS for nonpoini-source pollution control and planning. Such techniques can help characterize the diffuse sources of pollution at the landscape level. 52 refs., 6 figs., 1 tab.« less
Identification of active sources inside cavities using the equivalent source method-based free-field recovery technique

NASA Astrophysics Data System (ADS)

Bi, Chuan-Xing; Hu, Ding-Yu; Zhang, Yong-Bin; Jing, Wen-Qian

2015-06-01

In previous studies, an equivalent source method (ESM)-based technique for recovering the free sound field in a noisy environment has been successfully applied to exterior problems. In order to evaluate its performance when applied to a more general noisy environment, that technique is used to identify active sources inside cavities where the sound field is composed of the field radiated by active sources and that reflected by walls. A patch approach with two semi-closed surfaces covering the target active sources is presented to perform the measurements, and the field that would be radiated by these target active sources into free space is extracted from the mixed field by using the proposed technique, which will be further used as the input of nearfield acoustic holography for source identification. Simulation and experimental results validate the effectiveness of the proposed technique for source identification in cavities, and show the feasibility of performing the measurements with a double layer planar array.
A modular Space Station/Base electrical power system - Requirements and design study.

NASA Technical Reports Server (NTRS)

Eliason, J. T.; Adkisson, W. B.

1972-01-01

The requirements and procedures necessary for definition and specification of an electrical power system (EPS) for the future space station are discussed herein. The considered space station EPS consists of a replaceable main power module with self-contained auxiliary power, guidance, control, and communication subsystems. This independent power source may 'plug into' a space station module which has its own electrical distribution, control, power conditioning, and auxiliary power subsystems. Integration problems are discussed, and a transmission system selected with local floor-by-floor power conditioning and distribution in the station module. This technique eliminates the need for an immediate long range decision on the ultimate space base power sources by providing capability for almost any currently considered option.
1985 Particle Accelerator Conference: Accelerator Engineering and Technology, 11th, Vancouver, Canada, May 13-16, 1985, Proceedings

NASA Astrophysics Data System (ADS)

Strathdee, A.

1985-10-01

The topics discussed are related to high-energy accelerators and colliders, particle sources and electrostatic accelerators, controls, instrumentation and feedback, beam dynamics, low- and intermediate-energy circular accelerators and rings, RF and other acceleration systems, beam injection, extraction and transport, operations and safety, linear accelerators, applications of accelerators, radiation sources, superconducting supercolliders, new acceleration techniques, superconducting components, cryogenics, and vacuum. Accelerator and storage ring control systems are considered along with linear and nonlinear orbit theory, transverse and longitudinal instabilities and cures, beam cooling, injection and extraction orbit theory, high current dynamics, general beam dynamics, and medical and radioisotope applications. Attention is given to superconducting RF structures, magnet technology, superconducting magnets, and physics opportunities with relativistic heavy ion accelerators.
A Systematic Review of Techniques and Sources of Big Data in the Healthcare Sector.

PubMed

Alonso, Susel Góngora; de la Torre Díez, Isabel; Rodrigues, Joel J P C; Hamrioui, Sofiane; López-Coronado, Miguel

2017-10-14

The main objective of this paper is to present a review of existing researches in the literature, referring to Big Data sources and techniques in health sector and to identify which of these techniques are the most used in the prediction of chronic diseases. Academic databases and systems such as IEEE Xplore, Scopus, PubMed and Science Direct were searched, considering the date of publication from 2006 until the present time. Several search criteria were established as 'techniques' OR 'sources' AND 'Big Data' AND 'medicine' OR 'health', 'techniques' AND 'Big Data' AND 'chronic diseases', etc. Selecting the paper considered of interest regarding the description of the techniques and sources of Big Data in healthcare. It found a total of 110 articles on techniques and sources of Big Data on health from which only 32 have been identified as relevant work. Many of the articles show the platforms of Big Data, sources, databases used and identify the techniques most used in the prediction of chronic diseases. From the review of the analyzed research articles, it can be noticed that the sources and techniques of Big Data used in the health sector represent a relevant factor in terms of effectiveness, since it allows the application of predictive analysis techniques in tasks such as: identification of patients at risk of reentry or prevention of hospital or chronic diseases infections, obtaining predictive models of quality.
Engineering Design Handbook: Timing Systems and Components

DTIC Science & Technology

1975-12-01

23-1 23-2 Modular Components 23-2 23—3 Integrated Circuits 23—2 23—4 Matching Techniques 23-5 23-5 DC and AC Systems 23-7 23-6 Hybrid...Assembly Illustrating Modular Design . . 23—4 23-3 Characteristics of the Source 23—6 23—4 Characteristics of the Load 23—6 23—5 Matching Source and...4-1 INTRODUCTION There is a continuous demand for increased precision and accuracy in frequency control. Today fast time pulses are used in
Preceedings of the International Congress (12th), Corrosion Control for Low-Cost Reliability, Held in Houston, Texas on September 19 -24, 1993. Volume 2. Process Industries Plant Operations.

DTIC Science & Technology

1993-09-24

respectively. That study generally emphasized that the pollutant sources and concentrations indoors can be quite different from those outdoors. [he present...potent source .1 9 Another general argument can be applied to account for upward curvature at the low end, i.e., the lowest concen- tration cannot fall...conclusions can be reached. The technique of z-direction scaling by normalising Rq leads to similar values of Ra because both are averages obtained by
Planar regions of GaAs (001) prepared by Ga droplet motion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Changxi, E-mail: changxi.zheng@monash.edu; Tang, Wen-Xin; Jesson, David E., E-mail: jessonDE@cardiff.ac.uk

2016-07-15

The authors describe a simple method for obtaining planar regions of GaAs (001) suitable for surface science studies. The technique, which requires no buffer layer growth, atomic hydrogen source, or the introduction of As flux, employs controllable Ga droplet motion to create planar trail regions during Langmuir evaporation. Low-energy electron microscopy/diffraction techniques are applied to monitor the droplet motion and characterize the morphology and the surface reconstruction. It is found that the planar regions exhibit atomic flatness at the level of a high-quality buffer layer.
Visualization of Computational Fluid Dynamics

NASA Technical Reports Server (NTRS)

Gerald-Yamasaki, Michael; Hultquist, Jeff; Bryson, Steve; Kenwright, David; Lane, David; Walatka, Pamela; Clucas, Jean; Watson, Velvin; Lasinski, T. A. (Technical Monitor)

1995-01-01

Scientific visualization serves the dual purpose of exploration and exposition of the results of numerical simulations of fluid flow. Along with the basic visualization process which transforms source data into images, there are four additional components to a complete visualization system: Source Data Processing, User Interface and Control, Presentation, and Information Management. The requirements imposed by the desired mode of operation (i.e. real-time, interactive, or batch) and the source data have their effect on each of these visualization system components. The special requirements imposed by the wide variety and size of the source data provided by the numerical simulation of fluid flow presents an enormous challenge to the visualization system designer. We describe the visualization system components including specific visualization techniques and how the mode of operation and source data requirements effect the construction of computational fluid dynamics visualization systems.
Nanoparticle coated optical fibers for single microbubble generation

NASA Astrophysics Data System (ADS)

Pimentel-Domínguez, Reinher; Hernández-Cordero, Juan

2011-09-01

The study of bubbles and bubbly flows is important in various fields such as physics, chemistry, medicine, geophysics, and even the food industry. A wide variety of mechanical and acoustic techniques have been reported for bubble generation. Although a single bubble may be generated with these techniques, controlling the size and the mean lifetime of the bubble remains a difficult task. Most of the optical methods for generation of microbubbles involve high-power pulsed laser sources focused in absorbing media such as liquids or particle solutions. With these techniques, single micron-sized bubbles can be generated with typical mean lifetimes ranging from nano to microseconds. The main problem with these bubbles is their abrupt implosion: this produces a shock wave that can potentially produce damages on the surroundings. These effects have to be carefully controlled in biological applications and in laser surgery, but thus far, not many options are available to effectively control micron-size bubble growth. In this paper, we present a new technique to generate microbubbles in non-absorbing liquids. In contrast to previous reports, the proposed technique uses low-power and a CW radiation from a laser diode. The laser light is guided through an optical fiber whose output end has been coated with nanostructures. Upon immersing the tip of the fiber in ethanol or water, micron-size bubbles can be readily generated. With this technique, bubble growth can be controlled through adjustments on the laser power. We have obtained micron-sized bubbles with mean lifetimes in the range of seconds. Furthermore, the generated bubbles do not implode, as verified with a high-speed camera and flow visualization techniques.
Pollution prevention and control procedure case study: an application for petroleum refineries.

PubMed

Rodríguez, Encarnación; Martínez, Jose-Luis

2005-06-01

There is global environmental concern about the pollution from industries and other organizations that should not only be controlled but also prevented. Many alternatives are available to those in charge of environmental protection, but they should be able to draw on a systematic procedure to help implement prevention and control measures. At present, there are three immediate tasks: defining the objective of any environmental study, identifying the potential pollution sources, and selecting alternatives to these sources. However, it is necessary to evaluate these alternatives by using as large a number of criteria as possible and making them cumulative so as to enable the classification and selection of the best available techniques for each pollution source. The petroleum refining industry plays an important role in the developed economies and also has a potential for pollution generation that must be controlled. The best solution for all (i.e., petroleum companies, the public, and the environment) is pollution prevention, because this option will protect all of them and will also reduce costs in terms of lower raw materials consumption as well as reducing potential fines. The procedure we have presented in this article has been applied successfully.
Absolute calorimetric calibration of low energy brachytherapy sources

NASA Astrophysics Data System (ADS)

Stump, Kurt E.

In the past decade there has been a dramatic increase in the use of permanent radioactive source implants in the treatment of prostate cancer. A small radioactive source encapsulated in a titanium shell is used in this type of treatment. The radioisotopes used are generally 125I or 103Pd. Both of these isotopes have relatively short half-lives, 59.4 days and 16.99 days, respectively, and have low-energy emissions and a low dose rate. These factors make these sources well suited for this application, but the calibration of these sources poses significant metrological challenges. The current standard calibration technique involves the measurement of ionization in air to determine the source air-kerma strength. While this has proved to be an improvement over previous techniques, the method has been shown to be metrologically impure and may not be the ideal means of calbrating these sources. Calorimetric methods have long been viewed to be the most fundamental means of determining source strength for a radiation source. This is because calorimetry provides a direct measurement of source energy. However, due to the low energy and low power of the sources described above, current calorimetric methods are inadequate. This thesis presents work oriented toward developing novel methods to provide direct and absolute measurements of source power for low-energy low dose rate brachytherapy sources. The method is the first use of an actively temperature-controlled radiation absorber using the electrical substitution method to determine total contained source power of these sources. The instrument described operates at cryogenic temperatures. The method employed provides a direct measurement of source power. The work presented here is focused upon building a metrological foundation upon which to establish power-based calibrations of clinical-strength sources. To that end instrument performance has been assessed for these source strengths. The intent is to establish the limits of the current instrument to direct further work in this field. It has been found that for sources with powers above approximately 2 muW the instrument is able to determine the source power in agreement to within less than 7% of what is expected based upon the current source strength standard. For lower power sources, the agreement is still within the uncertainty of the power measurement, but the calorimeter noise dominates. Thus, to provide absolute calibration of lower power sources additional measures must be taken. The conclusion of this thesis describes these measures and how they will improve the factors that limit the current instrument. The results of the work presented in this thesis establish the methodology of active radiometric calorimetey for the absolute calibration of radioactive sources. The method is an improvement over previous techniques in that there is no reliance upon the thermal properties of the materials used or the heat flow pathways on the source measurements. The initial work presented here will help to shape future refinements of this technique to allow lower power sources to be calibrated with high precision and high accuracy.
Environmental effects of energy production and utilization in the U. S. Volume I. Sources, trends, and costs of control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newkirk, H.W.

1976-05-01

Volume I deals with sources (what the emissions are and where they come from), trends (quantities of emissions and their dispersion with time), and costs of control (what it takes in time, energy, and money to meet minimum standards). Volume II concerns itself with the public health effects of energy production and utilization. Volume III summarizes the various techniques for controlling emissions, technological as well as economic, social, and political. (For abstracts of Vols. II and III, see ERDA Energy Research Abstracts, Vol. 2, Absts. 5764 and 5670, respectively) Each volume is divided into sections dealing with the atmosphere, water,more » land, and social activities--each division indicating a particular sphere of man's environment affected by energy production and use. The sources of information that were used in this study included textbooks, journal articles, technical reports, memoranda, letters, and personal communications. These are cited in the text at the end of each subsection and on the applicable tables and figures.« less

Comprehensive Review of Adipose Stem Cells and Their Implication in Distraction Osteogenesis and Bone Regeneration

PubMed Central

Morcos, Mina W.; Al-Jallad, Hadil; Hamdy, Reggie

2015-01-01

Bone is one of the most dynamic tissues in the human body that can heal following injury without leaving a scar. However, in instances of extensive bone loss, this intrinsic capacity of bone to heal may not be sufficient and external intervention becomes necessary. Several techniques are available to address this problem, including autogenous bone grafts and allografts. However, all these techniques have their own limitations. An alternative method is the technique of distraction osteogenesis, where gradual and controlled distraction of two bony segments after osteotomy leads to induction of new bone formation. Although distraction osteogenesis usually gives satisfactory results, its major limitation is the prolonged duration of time required before the external fixator is removed, which may lead to numerous complications. Numerous methods to accelerate bone formation in the context of distraction osteogenesis have been reported. A viable alternative to autogenous bone grafts for a source of osteogenic cells is mesenchymal stem cells from bone marrow. However, there are certain problems with bone marrow aspirate. Hence, scientists have investigated other sources for mesenchymal stem cells, specifically adipose tissue, which has been shown to be an excellent source of mesenchymal stem cells. In this paper, the potential use of adipose stem cells to stimulate bone formation is discussed. PMID:26448947
Film fabrication of Fe or Fe3O4 nanoparticles mixed with palmitic acid for vertically aligned carbon nanotube growth using Langmuir-Blodgett technique

NASA Astrophysics Data System (ADS)

Nakamura, Kentaro; Kuriyama, Naoki; Takagiwa, Shota; Sato, Taiga; Kushida, Masahito

2016-03-01

Vertically aligned carbon nanotubes (VA-CNTs) were studied as a new catalyst support for polymer electrolyte fuel cells (PEFCs). Controlling the number density and the diameter of VA-CNTs may be necessary to optimize PEFC performance. As the catalyst for CNT growth, we fabricated Fe or Fe3O4 nanoparticle (NP) films by the Langmuir-Blodgett (LB) technique. The catalyst Fe or Fe3O4 NPs were widely separated by mixing with filler molecules [palmitic acid (C16)]. The number density of VA-CNTs was controlled by varying the ratio of catalyst NPs to C16 filler molecules. The VA-CNTs were synthesized from the catalyst NP-C16 LB films by thermal chemical vapor deposition (CVD) using acetylene gas as the carbon source. The developing solvents used in the LB technique and the hydrogen reduction conditions of CVD were optimized to improve the VA-CNT growth rate. We demonstrate that the proposed method can independently control both the density and the diameter of VA-CNTs.
Adaptive disturbance compensation finite control set optimal control for PMSM systems based on sliding mode extended state observer

NASA Astrophysics Data System (ADS)

Wu, Yun-jie; Li, Guo-fei

2018-01-01

Based on sliding mode extended state observer (SMESO) technique, an adaptive disturbance compensation finite control set optimal control (FCS-OC) strategy is proposed for permanent magnet synchronous motor (PMSM) system driven by voltage source inverter (VSI). So as to improve robustness of finite control set optimal control strategy, a SMESO is proposed to estimate the output-effect disturbance. The estimated value is fed back to finite control set optimal controller for implementing disturbance compensation. It is indicated through theoretical analysis that the designed SMESO could converge in finite time. The simulation results illustrate that the proposed adaptive disturbance compensation FCS-OC possesses better dynamical response behavior in the presence of disturbance.
Space shuttle program information control and retrieval system feasibility study report

NASA Technical Reports Server (NTRS)

Lingle, C. P.

1973-01-01

The feasibility of having a common information management network for space shuttle data, is studied. Identified are the information types required, sources and users of the information, and existing techniques for acquiring, storing and retrieving the data. The study concluded that a decentralized system is feasible, and described a recommended development plan for it.
Neutron-Activated Gamma-Emission: Technology Review

DTIC Science & Technology

2012-01-01

valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) January 2012 2. REPORT TYPE Progress 3... DATES COVERED (From - To) January to March 2010 4. TITLE AND SUBTITLE Neutron-Activated Gamma-Emission: Technology Review 5a. CONTRACT NUMBER...Backscatter Analysis Techniques........................................................................13 3. Sources of Neutrons 15 3.1 Radioisotope
Vaporization of a mixed precursors in chemical vapor deposition for YBCO films

NASA Technical Reports Server (NTRS)

Zhou, Gang; Meng, Guangyao; Schneider, Roger L.; Sarma, Bimal K.; Levy, Moises

1995-01-01

Single phase YBa2Cu3O7-delta thin films with T(c) values around 90 K are readily obtained by using a single source chemical vapor deposition technique with a normal precursor mass transport. The quality of the films is controlled by adjusting the carrier gas flow rate and the precursor feed rate.
Eye Movement Monitoring in the Study of Silent Reading.

ERIC Educational Resources Information Center

McConkie, George W.

Eye movement monitoring is useful both in the control of experiments on reading and as a source of data. Experiments using eye monitoring techniques have helped develop the following conclusions about the reading process: the region of text read during a fixation is quite small and asymmetric to the right of the center of vision, successive…
Control strategy on the double-diffusive convection in a nanofluid layer with internal heat generation

NASA Astrophysics Data System (ADS)

Mokhtar, N. F. M.; Khalid, I. K.; Siri, Z.; Ibrahim, Z. B.; Gani, S. S. A.

2017-10-01

The influences of feedback control and internal heat source on the onset of Rayleigh-Bénard convection in a horizontal nanofluid layer is studied analytically due to Soret and Dufour parameters. The confining boundaries of the nanofluid layer (bottom boundary-top boundary) are assumed to be free-free, rigid-free, and rigid-rigid, with a source of heat from below. Linear stability theory is applied, and the eigenvalue solution is obtained numerically using the Galerkin technique. Focusing on the stationary convection, it is shown that there is a positive thermal resistance in the presence of feedback control on the onset of double-diffusive convection, while there is a positive thermal efficiency in the existence of internal heat generation. The possibilities of suppress or augment of the Rayleigh-Bénard convection in a nanofluid layer are also discussed in detail.
Operational factors affecting microgravity levels in orbit

NASA Technical Reports Server (NTRS)

Olsen, R. E.; Mockovciak, J., Jr.

1980-01-01

Microgravity levels desired for proposed materials processing payloads are fundamental considerations in the design of future space platforms. Disturbance sources, such as aerodynamic drag, attitude control torques, crew motion and orbital dynamics, influence the microgravity levels attainable in orbit. The nature of these effects are assessed relative to platform design parameters such as orbital altitude and configuration geometry, and examples are presented for a representative spacecraft configuration. The possible applications of control techniques to provide extremely low acceleration levels are also discussed.
A compact inflow control device for simulating flight fan noise

NASA Technical Reports Server (NTRS)

Homyak, L.; Mcardle, J. G.; Heidelberg, L. J.

1983-01-01

Inflow control device (ICD's) of various shapes and sizes have been used to simulate inflight fan tone noise during ground static tests. A small, simple inexpensive ICD design was optimized from previous design and fabrication techniques. This compact two-fan-diameter ICD exhibits satisfactory acoustic performance characteristics without causing noise attenuation or redirection. In addition, it generates no important new noise sources. Design and construction details of the compact ICD are discussed and acoustic performance test results are presented.
Universal main magnetic focus ion source for production of highly charged ions

NASA Astrophysics Data System (ADS)

Ovsyannikov, V. P.; Nefiodov, A. V.; Levin, A. A.

2017-10-01

A novel room-temperature compact ion source has been developed for the efficient production of atomic ions by means of an electron beam with energy Ee and current density je controllable within wide ranges (100 eV ≲Ee ≲ 60 keV, 10 A/cm2 ≲je ≲ 20 kA/cm2). In the first experiments, the X-ray emission of Ir64+ ions has been measured. Based on a combination of two different techniques, the device can operate both as conventional Electron Beam Ion Source/Trap and novel Main Magnetic Focus Ion Source. The tunable electron-optical system allows for realizing laminar and turbulent electron flows in a single experimental setup. The device is intended primarily for fundamental and applied research at standard university laboratories.
Novel method to control antenna currents based on theory of characteristic modes

NASA Astrophysics Data System (ADS)

Elghannai, Ezdeen Ahmed

Characteristic Mode Theory is one of the very few numerical methods that provide a great deal of physical insight because it allows us to determine the natural modes of the radiating structure. The key feature of these modes is that the total induced antenna current, input impedance/admittance and radiation pattern can be expressed as a linear weighted combination of individual modes. Using this decomposition method, it is possible to study the behavior of the individual modes, understand them and therefore control the antennas behavior; in other words, control the currents induced on the antenna structure. This dissertation advances the topic of antenna design by carefully controlling the antenna currents over the desired frequency band to achieve the desired performance specifications for a set of constraints. Here, a systematic method based on the Theory of Characteristic Modes (CM) and lumped reactive loading to achieve the goal of current control is developed. The lumped reactive loads are determined based on the desired behavior of the antenna currents. This technique can also be used to impedance match the antenna to the source/generator connected to it. The technique is much more general than the traditional impedance matching. Generally, the reactive loads that properly control the currents exhibit a combination of Foster and non-Foster behavior. The former can be implemented with lumped passive reactive components, while the latter can be implemented with lumped non-Foster circuits (NFC). The concept of current control is applied to design antennas with a wide band (impedance/pattern) behavior using reactive loads. We successfully applied this novel technique to design multi band and wide band antennas for wireless applications. The technique was developed to match the antenna to resistive and/or complex source impedance and control the radiation pattern at these frequency bands, considering size and volume constraints. A wide band patch antenna was achieved using the developed technique. In addition, the technique was applied to multi band wire less Universal Serial Bus (USB) dongle antenna that serves for WLAN IEEE 802.11 a/b/g/n band applications and Radio Frequency Identification (RFID) tag antenna for 915MHz band applications with superior performance compared to previous published results. This dissertation also discusses the total Q of an antenna from the CM standpoint. A new expression as well as additional physical information about each mode's individual contribution to the total antenna Q are provided. Finally, the theory is used to an analyze the antenna in both radiation and/or scattering modes. In the antenna scattering mode, the field scattered by an antenna contains a component that is the short circuit scattered field, and a second component that is proportional to the radiation field. In this dissertation, an analytical study of this phenomena from the CM standpoint is performed aiming to shed some light on antenna scattering phenomenon where additional physical insight is obtained and thus used to reach desire results.
Spatial interpolation methods and geostatistics for mapping groundwater contamination in a coastal area.

PubMed

Elumalai, Vetrimurugan; Brindha, K; Sithole, Bongani; Lakshmanan, Elango

2017-04-01

Mapping groundwater contaminants and identifying the sources are the initial steps in pollution control and mitigation. Due to the availability of different mapping methods and the large number of emerging pollutants, these methods need to be used together in decision making. The present study aims to map the contaminated areas in Richards Bay, South Africa and compare the results of ordinary kriging (OK) and inverse distance weighted (IDW) interpolation techniques. Statistical methods were also used for identifying contamination sources. Na-Cl groundwater type was dominant followed by Ca-Mg-Cl. Data analysis indicate that silicate weathering, ion exchange and fresh water-seawater mixing are the major geochemical processes controlling the presence of major ions in groundwater. Factor analysis also helped to confirm the results. Overlay analysis by OK and IDW gave different results. Areas where groundwater was unsuitable as a drinking source were 419 and 116 km 2 for OK and IDW, respectively. Such diverse results make decision making difficult, if only one method was to be used. Three highly contaminated zones within the study area were more accurately identified by OK. If large areas are identified as being contaminated such as by IDW in this study, the mitigation measures will be expensive. If these areas were underestimated, then even though management measures are taken, it will not be effective for a longer time. Use of multiple techniques like this study will help to avoid taking harsh decisions. Overall, the groundwater quality in this area was poor, and it is essential to identify alternate drinking water source or treat the groundwater before ingestion.
CERTS Microgrid Laboratory Test Bed - PIER Final Project Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eto, Joseph H.; Eto, Joseph H.; Lasseter, Robert

2008-07-25

The objective of the CERTS Microgrid Laboratory Test Bed project was to enhance the ease of integrating small energy sources into a microgrid. The project accomplished this objective by developing and demonstrating three advanced techniques, collectively referred to as the CERTS Microgrid concept, that significantly reduce the level of custom field engineering needed to operate microgrids consisting of small generating sources. The techniques comprising the CERTS Microgrid concept are: 1) a method for effecting automatic and seamless transitions between grid-connected and islanded modes of operation; 2) an approach to electrical protection within the microgrid that does not depend on highmore » fault currents; and 3) a method for microgrid control that achieves voltage and frequency stability under islanded conditions without requiring high-speed communications. The techniques were demonstrated at a full-scale test bed built near Columbus, Ohio and operated by American Electric Power. The testing fully confirmed earlier research that had been conducted initially through analytical simulations, then through laboratory emulations, and finally through factory acceptance testing of individual microgrid components. The islanding and resychronization method met all Institute of Electrical and Electronics Engineers 1547 and power quality requirements. The electrical protections system was able to distinguish between normal and faulted operation. The controls were found to be robust and under all conditions, including difficult motor starts. The results from these test are expected to lead to additional testing of enhancements to the basic techniques at the test bed to improve the business case for microgrid technologies, as well to field demonstrations involving microgrids that involve one or mroe of the CERTS Microgrid concepts.« less
A universal heliostat control system

NASA Astrophysics Data System (ADS)

Gross, Fabian; Geiger, Mark; Buck, Reiner

2017-06-01

This paper describes the development of a universal heliostat control system as part of the AutoR project [1]. The system can control multiple receivers and heliostat types in a single application. The system offers support for multiple operators on different machines and is designed to be as adaptive as possible. Thus, the system can be used for different heliostat field setups with only minor adaptations of the system's source code. This is achieved by extensive usage of modern programming techniques like reflection and dependency injection. Furthermore, the system features co-simulation of a ray tracer, a reference PID-controller implementation for open volumetric receivers and methods for heliostat calibration and monitoring.
Comparison of four different techniques to evaluate the elastic properties of phantom in elastography: is there a gold standard?

NASA Astrophysics Data System (ADS)

Oudry, Jennifer; Lynch, Ted; Vappou, Jonathan; Sandrin, Laurent; Miette, Véronique

2014-10-01

Elastographic techniques used in addition to imaging techniques (ultrasound, resonance magnetic or optical) provide new clinical information on the pathological state of soft tissues. However, system-dependent variation in elastographic measurements may limit the clinical utility of these measurements by introducing uncertainty into the measurement. This work is aimed at showing differences in the evaluation of the elastic properties of phantoms performed by four different techniques: quasi-static compression, dynamic mechanical analysis, vibration-controlled transient elastography and hyper-frequency viscoelastic spectroscopy. Four Zerdine® gel materials were tested and formulated to yield a Young’s modulus over the range of normal and cirrhotic liver stiffnesses. The Young’s modulus and the shear wave speed obtained with each technique were compared. Results suggest a bias in elastic property measurement which varies with systems and highlight the difficulty in finding a reference method to determine and assess the elastic properties of tissue-mimicking materials. Additional studies are needed to determine the source of this variation, and control for them so that accurate, reproducible reference standards can be made for the absolute measurement of soft tissue elasticity.
Comparison of four different techniques to evaluate the elastic properties of phantom in elastography: is there a gold standard?

PubMed

Oudry, Jennifer; Lynch, Ted; Vappou, Jonathan; Sandrin, Laurent; Miette, Véronique

2014-10-07

Elastographic techniques used in addition to imaging techniques (ultrasound, resonance magnetic or optical) provide new clinical information on the pathological state of soft tissues. However, system-dependent variation in elastographic measurements may limit the clinical utility of these measurements by introducing uncertainty into the measurement. This work is aimed at showing differences in the evaluation of the elastic properties of phantoms performed by four different techniques: quasi-static compression, dynamic mechanical analysis, vibration-controlled transient elastography and hyper-frequency viscoelastic spectroscopy. Four Zerdine® gel materials were tested and formulated to yield a Young's modulus over the range of normal and cirrhotic liver stiffnesses. The Young's modulus and the shear wave speed obtained with each technique were compared. Results suggest a bias in elastic property measurement which varies with systems and highlight the difficulty in finding a reference method to determine and assess the elastic properties of tissue-mimicking materials. Additional studies are needed to determine the source of this variation, and control for them so that accurate, reproducible reference standards can be made for the absolute measurement of soft tissue elasticity.
Intrinsic and extrinsic parameters for controlling the growth of organic single-crystalline nanopillars in photovoltaics.

PubMed

Zhang, Yue; Diao, Ying; Lee, Hyunbok; Mirabito, Timothy J; Johnson, Richard W; Puodziukynaite, Egle; John, Jacob; Carter, Kenneth R; Emrick, Todd; Mannsfeld, Stefan C B; Briseno, Alejandro L

2014-10-08

The most efficient architecture for achieving high donor/acceptor interfacial area in organic photovoltaics (OPVs) would employ arrays of vertically interdigitated p- and n- type semiconductor nanopillars (NPs). Such morphology could have an advantage in bulk heterojunction systems; however, precise control of the dimension morphology in a crystalline, interpenetrating architecture has not yet been realized. Here we present a simple, yet facile, crystallization technique for the growth of vertically oriented NPs utilizing a modified thermal evaporation technique that hinges on a fast deposition rate, short substrate-source distance, and ballistic mass transport. A broad range of organic semiconductor materials is beneficial from the technique to generate NP geometries. Moreover, this technique can also be generalized to various substrates, namely, graphene, PEDOT-PSS, ZnO, CuI, MoO3, and MoS2. The advantage of the NP architecture over the conventional thin film counterpart is demonstrated with an increase of power conversion efficiency of 32% in photovoltaics. This technique will advance the knowledge of organic semiconductor crystallization and create opportunities for the fabrication and processing of NPs for applications that include solar cells, charge storage devices, sensors, and vertical transistors.
Modeling and analysis of CSAMT field source effect and its characteristics

NASA Astrophysics Data System (ADS)

Da, Lei; Xiaoping, Wu; Qingyun, Di; Gang, Wang; Xiangrong, Lv; Ruo, Wang; Jun, Yang; Mingxin, Yue

2016-02-01

Controlled-source audio-frequency magnetotellurics (CSAMT) has been a highly successful geophysical tool used in a variety of geological exploration studies for many years. However, due to the artificial source used in the CSAMT technique, two important factors are considered during interpretation: non-plane-wave or geometric effects and source overprint effects. Hence, in this paper we simulate the source overprint effects and analyzed the rule and characteristics of its influence on CSAMT applications. Two-dimensional modeling was carried out using an adaptive unstructured finite element method to simulate several typical models. Also, we summarized the characteristics and rule of the source overprint effects and analyzed its influence on the data taken over several mining areas. The results obtained from the study shows that the occurrence and strength of the source overprint effect is dependent on the location of the source dipole, in relation to the receiver and the subsurface geology. In order to avoid source overprint effects, three principle were suggested to determine the best location for the grounded dipole source in the field.
Modeling, Analysis and Mitigation of Sub-Synchronous Interactions between Full- and Partial-Scale Voltage-Source Converters and Power Networks

NASA Astrophysics Data System (ADS)

Alawasa, Khaled Mohammad

Voltage-source converters (VSCs) have gained widespread acceptance in modern power systems. The stability and dynamics of power systems involving these devices have recently become salient issues. In the small-signal sense, the dynamics of VSC-based systems is dictated by its incremental output impedance, which is formed by a combination of 'passive' circuit components and 'active' control elements. Control elements such as control parameters, control loops, and control topologies play a significant role in shaping the impedance profile. Depending on the control schemes and strategies used, VSC-based systems can exhibit different incremental impedance dynamics. As the control elements and dynamics are involved in the impedance structure, the frequency-dependent output impedance might have a negative real-part (i.e., a negative resistance). In the grid-connected mode, the negative resistance degrades the system damping and negatively impacts the stability. In high-voltage networks where high-power VSC-based systems are usually employed and where sub-synchronous dynamics usually exist, integrating large VSC-based systems might reduce the overall damping and results in unstable dynamics. The objectives of this thesis are to (1) investigate and analyze the output impedance properties under different control strategies and control functions, (2) identify and characterize the key contributors to the impedance and sub-synchronous damping profiles, and (3) propose mitigation techniques to minimize and eliminate the negative impact associated with integrating VSC-based systems into power systems. Different VSC configurations are considered in this thesis; in particular, the full-scale and partial-scale topologies (doubly fed-induction generators) are addressed. Additionally, the impedance and system damping profiles are studied under two different control strategies: the standard vector control strategy and the recently-developed power synchronization control strategy. Furthermore, this thesis proposes a simple and robust technique for damping the sub-synchronous resonance in a power system.

Intelligent Systems Approach for Automated Identification of Individual Control Behavior of a Human Operator

NASA Technical Reports Server (NTRS)

Zaychik, Kirill B.; Cardullo, Frank M.

2012-01-01

Results have been obtained using conventional techniques to model the generic human operator?s control behavior, however little research has been done to identify an individual based on control behavior. The hypothesis investigated is that different operators exhibit different control behavior when performing a given control task. Two enhancements to existing human operator models, which allow personalization of the modeled control behavior, are presented. One enhancement accounts for the testing control signals, which are introduced by an operator for more accurate control of the system and/or to adjust the control strategy. This uses the Artificial Neural Network which can be fine-tuned to model the testing control. Another enhancement takes the form of an equiripple filter which conditions the control system power spectrum. A novel automated parameter identification technique was developed to facilitate the identification process of the parameters of the selected models. This utilizes a Genetic Algorithm based optimization engine called the Bit-Climbing Algorithm. Enhancements were validated using experimental data obtained from three different sources: the Manual Control Laboratory software experiments, Unmanned Aerial Vehicle simulation, and NASA Langley Research Center Visual Motion Simulator studies. This manuscript also addresses applying human operator models to evaluate the effectiveness of motion feedback when simulating actual pilot control behavior in a flight simulator.
Analysis of Nonvolatile Residue (NVR) from Spacecraft Systems

NASA Technical Reports Server (NTRS)

Colony, J. A.

1985-01-01

Organic contamination on critical spacecraft surfaces can cause electronic problems, serious attenuation of various optical signals, thermal control changes, and adhesion problems. Such contaminants can be detected early by the controlled use of witness mirrors, witness plates, wipe sampling, or direct solvent extraction. Each method requires careful control of variables of technique and materials to attain the ultimate sensitivities inherent to that procedure. Subsequent chemical analysis of the contaminant sample by infrared and mass spectrometry identifies the components, gives semiquantitative estimates of contaminant thickness, indicates possible sources of the nonvolatile residue (NVR), and provides guidance for effective cleanup procedures.
Indirect adaptive soft computing based wavelet-embedded control paradigms for WT/PV/SOFC in a grid/charging station connected hybrid power system.

PubMed

Mumtaz, Sidra; Khan, Laiq; Ahmed, Saghir; Bader, Rabiah

2017-01-01

This paper focuses on the indirect adaptive tracking control of renewable energy sources in a grid-connected hybrid power system. The renewable energy systems have low efficiency and intermittent nature due to unpredictable meteorological conditions. The domestic load and the conventional charging stations behave in an uncertain manner. To operate the renewable energy sources efficiently for harvesting maximum power, instantaneous nonlinear dynamics should be captured online. A Chebyshev-wavelet embedded NeuroFuzzy indirect adaptive MPPT (maximum power point tracking) control paradigm is proposed for variable speed wind turbine-permanent synchronous generator (VSWT-PMSG). A Hermite-wavelet incorporated NeuroFuzzy indirect adaptive MPPT control strategy for photovoltaic (PV) system to extract maximum power and indirect adaptive tracking control scheme for Solid Oxide Fuel Cell (SOFC) is developed. A comprehensive simulation test-bed for a grid-connected hybrid power system is developed in Matlab/Simulink. The robustness of the suggested indirect adaptive control paradigms are evaluated through simulation results in a grid-connected hybrid power system test-bed by comparison with conventional and intelligent control techniques. The simulation results validate the effectiveness of the proposed control paradigms.
Indirect adaptive soft computing based wavelet-embedded control paradigms for WT/PV/SOFC in a grid/charging station connected hybrid power system

PubMed Central

Khan, Laiq; Ahmed, Saghir; Bader, Rabiah

2017-01-01

This paper focuses on the indirect adaptive tracking control of renewable energy sources in a grid-connected hybrid power system. The renewable energy systems have low efficiency and intermittent nature due to unpredictable meteorological conditions. The domestic load and the conventional charging stations behave in an uncertain manner. To operate the renewable energy sources efficiently for harvesting maximum power, instantaneous nonlinear dynamics should be captured online. A Chebyshev-wavelet embedded NeuroFuzzy indirect adaptive MPPT (maximum power point tracking) control paradigm is proposed for variable speed wind turbine-permanent synchronous generator (VSWT-PMSG). A Hermite-wavelet incorporated NeuroFuzzy indirect adaptive MPPT control strategy for photovoltaic (PV) system to extract maximum power and indirect adaptive tracking control scheme for Solid Oxide Fuel Cell (SOFC) is developed. A comprehensive simulation test-bed for a grid-connected hybrid power system is developed in Matlab/Simulink. The robustness of the suggested indirect adaptive control paradigms are evaluated through simulation results in a grid-connected hybrid power system test-bed by comparison with conventional and intelligent control techniques. The simulation results validate the effectiveness of the proposed control paradigms. PMID:28877191
Charting a Path to Location Intelligence for STD Control.

PubMed

Gerber, Todd M; Du, Ping; Armstrong-Brown, Janelle; McNutt, Louise-Anne; Coles, F Bruce

2009-01-01

This article describes the New York State Department of Health's GeoDatabase project, which developed new methods and techniques for designing and building a geocoding and mapping data repository for sexually transmitted disease (STD) control. The GeoDatabase development was supported through the Centers for Disease Control and Prevention's Outcome Assessment through Systems of Integrated Surveillance workgroup. The design and operation of the GeoDatabase relied upon commercial-off-the-shelf tools that other public health programs may also use for disease-control systems. This article provides a blueprint of the structure and software used to build the GeoDatabase and integrate location data from multiple data sources into the everyday activities of STD control programs.
Preliminary experiments on active control of fan noise from a turbofan engine

NASA Technical Reports Server (NTRS)

Thomas, R. H.; Burdisso, R. A.; Fuller, C. R.; O'Brien, W. F.

1993-01-01

In the preliminary experiments reported here, active acoustic sources positioned around the circumference of a turbofan engine were used to control the fan noise radiated forward through the inlet. The main objective was to demonstrate the potential of active techniques to alleviate the noise pollution that will be produced by the next generation of larger engines. A reduction of up to 19 dB in the radiation directivity was demonstrated in a zone that encompasses a 30-deg angle, near the error sensor, while spillover effects were observed toward the lateral direction. The simultaneous control of two tones was also demonstrated using two identical controllers in a parallel control configuration.
Use of PZT's for adaptive control of Fabry-Perot etalon plate figure

NASA Technical Reports Server (NTRS)

Skinner, WIlbert; Niciejewski, R.

2005-01-01

A Fabry Perot etalon, consisting of two spaced and reflective glass flats, provides the mechanism by which high resolution spectroscopy may be performed over narrow spectral regions. Space based applications include direct measurements of Doppler shifts of airglow absorption and emission features and the Doppler broadening of spectral lines. The technique requires a high degree of parallelism between the two flats to be maintained through harsh launch conditions. Monitoring and adjusting the plate figure by illuminating the Fabry Perot interferometer with a suitable monochromatic source may be performed on orbit to actively control of the parallelism of the flats. This report describes the use of such a technique in a laboratory environment applied to a piezo-electric stack attached to the center of a Fabry Perot etalon.
Exploring the structure of high temperature, iron-bearing liquids

DOE PAGES

Wilding, Martin; Benmore, Chris; Weber, Rick; ...

2015-06-25

This paper describes the direct measurements of the structure of iron-bearing liquids using a combination of containerless techniques and in–situ high energy x-ray diffraction. These capabilities provide data that is important to help model and optimize processes such as smelting, steel making, and controlling slag chemistry. A successful programme of liquid studies has been undertaken and the Advanced Photon Source using these combined techniques which include the provision of gas mixing and the control of pO₂ and the changing influence of mixed valance elements. It is possible to combine rapid image acquisition with quenching of liquids to obtain the fullmore » diffraction patterns of deeply supercooled liquids and the metastable supercooled liquid regime, where the liquid structures and viscosity change most dramatically, can also be explored.« less
The use of the virtual source technique in computing scattering from periodic ocean surfaces.

PubMed

Abawi, Ahmad T

2011-08-01

In this paper the virtual source technique is used to compute scattering of a plane wave from a periodic ocean surface. The virtual source technique is a method of imposing boundary conditions using virtual sources, with initially unknown complex amplitudes. These amplitudes are then determined by applying the boundary conditions. The fields due to these virtual sources are given by the environment Green's function. In principle, satisfying boundary conditions on an infinite surface requires an infinite number of sources. In this paper, the periodic nature of the surface is employed to populate a single period of the surface with virtual sources and m surface periods are added to obtain scattering from the entire surface. The use of an accelerated sum formula makes it possible to obtain a convergent sum with relatively small number of terms (∼40). The accuracy of the technique is verified by comparing its results with those obtained using the integral equation technique.
On-board data management study for EOPAP

NASA Technical Reports Server (NTRS)

Davisson, L. D.

1975-01-01

The requirements, implementation techniques, and mission analysis associated with on-board data management for EOPAP were studied. SEASAT-A was used as a baseline, and the storage requirements, data rates, and information extraction requirements were investigated for each of the following proposed SEASAT sensors: a short pulse 13.9 GHz radar, a long pulse 13.9 GHz radar, a synthetic aperture radar, a multispectral passive microwave radiometer facility, and an infrared/visible very high resolution radiometer (VHRR). Rate distortion theory was applied to determine theoretical minimum data rates and compared with the rates required by practical techniques. It was concluded that practical techniques can be used which approach the theoretically optimum based upon an empirically determined source random process model. The results of the preceding investigations were used to recommend an on-board data management system for (1) data compression through information extraction, optimal noiseless coding, source coding with distortion, data buffering, and data selection under command or as a function of data activity, (2) for command handling, (3) for spacecraft operation and control, and (4) for experiment operation and monitoring.
Vibration Method for Tracking the Resonant Mode and Impedance of a Microwave Cavity

NASA Technical Reports Server (NTRS)

Barmatz, M.; Iny, O.; Yiin, T.; Khan, I.

1995-01-01

A vibration technique his been developed to continuously maintain mode resonance and impedance much between a constant frequency magnetron source and resonant cavity. This method uses a vibrating metal rod to modulate the volume of the cavity in a manner equivalent to modulating an adjustable plunger. A similar vibrating metal rod attached to a stub tuner modulates the waveguide volume between the source and cavity. A phase sensitive detection scheme determines the optimum position of the adjustable plunger and stub turner during processing. The improved power transfer during the heating of a 99.8% pure alumina rod was demonstrated using this new technique. Temperature-time and reflected power-time heating curves are presented for the cases of no tracking, impedance tracker only, mode tracker only and simultaneous impedance and mode tracking. Controlled internal melting of an alumina rod near 2000 C using both tracking units was also demonstrated.
Methods and apparatus for broadband frequency comb stabilization

DOEpatents

Cox, Jonathan A; Kaertner, Franz X

2015-03-17

Feedback loops can be used to shift and stabilize the carrier-envelope phase of a frequency comb from a mode-locked fibers laser or other optical source. Compared to other frequency shifting and stabilization techniques, feedback-based techniques provide a wideband closed-loop servo bandwidth without optical filtering, beam pointing errors, or group velocity dispersion. It also enables phase locking to a stable reference, such as a Ti:Sapphire laser, continuous-wave microwave or optical source, or self-referencing interferometer, e.g., to within 200 mrad rms from DC to 5 MHz. In addition, stabilized frequency combs can be coherently combined with other stable signals, including other stabilized frequency combs, to synthesize optical pulse trains with pulse durations of as little as a single optical cycle. Such a coherent combination can be achieved via orthogonal control, using balanced optical cross-correlation for timing stabilization and balanced homodyne detection for phase stabilization.
Spatial patterns of heavy metals in soil under different geological structures and land uses for assessing metal enrichments.

PubMed

Krami, Loghman Khoda; Amiri, Fazel; Sefiyanian, Alireza; Shariff, Abdul Rashid B Mohamed; Tabatabaie, Tayebeh; Pradhan, Biswajeet

2013-12-01

One hundred and thirty composite soil samples were collected from Hamedan county, Iran to characterize the spatial distribution and trace the sources of heavy metals including As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn, and Fe. The multivariate gap statistical analysis was used; for interrelation of spatial patterns of pollution, the disjunctive kriging and geoenrichment factor (EF(G)) techniques were applied. Heavy metals and soil properties were grouped using agglomerative hierarchical clustering and gap statistic. Principal component analysis was used for identification of the source of metals in a set of data. Geostatistics was used for the geospatial data processing. Based on the comparison between the original data and background values of the ten metals, the disjunctive kriging and EF(G) techniques were used to quantify their geospatial patterns and assess the contamination levels of the heavy metals. The spatial distribution map combined with the statistical analysis showed that the main source of Cr, Co, Ni, Zn, Pb, and V in group A land use (agriculture, rocky, and urban) was geogenic; the origin of As, Cd, and Cu was industrial and agricultural activities (anthropogenic sources). In group B land use (rangeland and orchards), the origin of metals (Cr, Co, Ni, Zn, and V) was mainly controlled by natural factors and As, Cd, Cu, and Pb had been added by organic factors. In group C land use (water), the origin of most heavy metals is natural without anthropogenic sources. The Cd and As pollution was relatively more serious in different land use. The EF(G) technique used confirmed the anthropogenic influence of heavy metal pollution. All metals showed concentrations substantially higher than their background values, suggesting anthropogenic pollution.
Management of fluid mud in estuaries, bays, and lakes. II: Measurement, modeling, and management

USGS Publications Warehouse

McAnally, W.H.; Teeter, A.; Schoellhamer, David H.; Friedrichs, C.; Hamilton, D.; Hayter, E.; Shrestha, P.; Rodriguez, H.; Sheremet, A.; Kirby, R.

2007-01-01

Techniques for measurement, modeling, and management of fluid mud are available, but research is needed to improve them. Fluid mud can be difficult to detect, measure, or sample, which has led to new instruments and new ways of using existing instruments. Multifrequency acoustic fathometers sense neither density nor viscosity and are, therefore, unreliable in measuring fluid mud. Nuclear density probes, towed sleds, seismic, and drop probes equipped with density meters offer the potential for accurate measurements. Numerical modeling of fluid mud requires solving governing equations for flow velocity, density, pressure, salinity, water surface, plus sediment submodels. A number of such models exist in one-, two-, and three-dimensional form, but they rely on empirical relationships that require substantial site-specific validation to observations. Management of fluid mud techniques can be classified as those that accomplish: Source control, formation control, and removal. Nautical depth, a fourth category, defines the channel bottom as a specific fluid mud density or alternative parameter as safe for navigation. Source control includes watershed management measures to keep fine sediment out of waterways and in-water measures such as structures and traps. Formation control methods include streamlined channels and structures plus other measures to reduce flocculation and structures that train currents. Removal methods include the traditional dredging and transport of dredged material plus agitation that contributes to formation control and/or nautical depth. Conditioning of fluid mud by dredging and aerating offers the possibility of improved navigability. Two examples—the Atchafalaya Bar Channel and Savannah Harbor—illustrate the use of measurements and management of fluid mud.
Open-Source Data Collection Techniques for Weapons Transfer Information

DTIC Science & Technology

2012-03-01

IR Infrared ISO International Organization for Standardization ITAR International Traffic in Arms Regulations NER Named Entity Recognition NLP ...Control Protocol UAE United Arab Emirates URI Uniform Resource Identifier URL Uniform Resource Locator USSR Union of Soviet Socialist Republics UTF...KOREA, DEMOCRATIC PEOPLE’S REPUBLIC OF North Korea KOREA, REPUBLIC OF South Korea LIBYAN ARAB JAMAHIRIYA Libya RUSSIAN FEDERATION Russia Table 3
DOE Office of Scientific and Technical Information (OSTI.GOV)

Abudureyimu, Reheman; Huang, Chunning; Liu, Yun

We report on a first experimental demonstration of locking a doubly-resonant Fabry-Perot cavity to burst-mode picosecond ultraviolet (UV) pulses by using a temperature controlled dispersion compensation method. This technique will eventually enable the intra cavity power enhancement of burst-mode 402.5MHz/50ps UV laser pulses with a MW level peak power required for the laser assisted H- beam stripping experiment at the Spallation Neutron Source.
An Incremental Life-cycle Assurance Strategy for Critical System Certification

DTIC Science & Technology

2014-11-04

for Safe Aircraft Operation Embedded software systems introduce a new class of problems not addressed by traditional system modeling & analysis...Platform Runtime Architecture Application Software Embedded SW System Engineer Data Stream Characteristics Latency jitter affects control behavior...do system level failures still occur despite fault tolerance techniques being deployed in systems ? Embedded software system as major source of
Visualizing medium and biodistribution in complex cell culture bioreactors using in vivo imaging.

PubMed

Ratcliffe, E; Thomas, R J; Stacey, A J

2014-01-01

There is a dearth of technology and methods to aid process characterization, control and scale-up of complex culture platforms that provide niche micro-environments for some stem cell-based products. We have demonstrated a novel use of 3d in vivo imaging systems to visualize medium flow and cell distribution within a complex culture platform (hollow fiber bioreactor) to aid characterization of potential spatial heterogeneity and identify potential routes of bioreactor failure or sources of variability. This can then aid process characterization and control of such systems with a view to scale-up. Two potential sources of variation were observed with multiple bioreactors repeatedly imaged using two different imaging systems: shortcutting of medium between adjacent inlet and outlet ports with the potential to create medium gradients within the bioreactor, and localization of bioluminescent murine 4T1-luc2 cells upon inoculation with the potential to create variable seeding densities at different points within the cell growth chamber. The ability of the imaging technique to identify these key operational bioreactor characteristics demonstrates an emerging technique in troubleshooting and engineering optimization of bioreactor performance. © 2013 American Institute of Chemical Engineers.
Minimization of nanosatellite low frequency magnetic fields.

PubMed

Belyayev, S M; Dudkin, F L

2016-03-01

Small weight and dimensions of the micro- and nanosatellites constrain researchers to place electromagnetic sensors on short booms or on the satellite body. Therefore the electromagnetic cleanliness of such satellites becomes a central question. This paper describes the theoretical base and practical techniques for determining the parameters of DC and very low frequency magnetic interference sources. One of such sources is satellite magnetization, the reduction of which improves the accuracy and stability of the attitude control system. We present design solutions for magnetically clean spacecraft, testing equipment, and technology for magnetic moment measurements, which are more convenient, efficient, and accurate than the conventional ones.
Wind-energy recovery by a static Scherbius induction generator

NASA Astrophysics Data System (ADS)

Smith, G. A.; Nigim, K. A.

1981-11-01

The paper describes a technique for controlling a doubly fed induction generator driven by a windmill, or other form of variable-speed prime mover, to provide power generation into the national grid system. The secondary circuit of the generator is supplied at a variable frequency from a current source inverter which for test purposes is rated to allow energy recovery, from a simulated windmill, from maximum speed to standstill. To overcome the stability problems normally associated with doubly fed machines a novel signal generator, which is locked in phase with the rotor EMF, controls the secondary power to provide operation over a wide range of subsynchronous and supersynchronous speeds. Consideration of power flow enables the VA rating of the secondary power source to be determined as a function of the gear ratio and online operating range of the system. A simple current source model is used to predict performance which is compared with experimental results. The results indicate a viable system, and suggestions for further work are proposed.

A study of methods to predict and measure the transmission of sound through the walls of light aircraft

NASA Technical Reports Server (NTRS)

Bernhard, R. J.; Bolton, J. S.

1988-01-01

The objectives are: measurement of dynamic properties of acoustical foams and incorporation of these properties in models governing three-dimensional wave propagation in foams; tests to measure sound transmission paths in the HP137 Jetstream 3; and formulation of a finite element energy model. In addition, the effort to develop a numerical/empirical noise source identification technique was completed. The investigation of a design optimization technique for active noise control was also completed. Monthly progress reports which detail the progress made toward each of the objectives are summarized.
Different types of maximum power point tracking techniques for renewable energy systems: A survey

NASA Astrophysics Data System (ADS)

Khan, Mohammad Junaid; Shukla, Praveen; Mustafa, Rashid; Chatterji, S.; Mathew, Lini

2016-03-01

Global demand for electricity is increasing while production of energy from fossil fuels is declining and therefore the obvious choice of the clean energy source that is abundant and could provide security for development future is energy from the sun. In this paper, the characteristic of the supply voltage of the photovoltaic generator is nonlinear and exhibits multiple peaks, including many local peaks and a global peak in non-uniform irradiance. To keep global peak, MPPT is the important component of photovoltaic systems. Although many review articles discussed conventional techniques such as P & O, incremental conductance, the correlation ripple control and very few attempts have been made with intelligent MPPT techniques. This document also discusses different algorithms based on fuzzy logic, Ant Colony Optimization, Genetic Algorithm, artificial neural networks, Particle Swarm Optimization Algorithm Firefly, Extremum seeking control method and hybrid methods applied to the monitoring of maximum value of power at point in systems of photovoltaic under changing conditions of irradiance.
Fast in-database cross-matching of high-cadence, high-density source lists with an up-to-date sky model

NASA Astrophysics Data System (ADS)

Scheers, B.; Bloemen, S.; Mühleisen, H.; Schellart, P.; van Elteren, A.; Kersten, M.; Groot, P. J.

2018-04-01

Coming high-cadence wide-field optical telescopes will image hundreds of thousands of sources per minute. Besides inspecting the near real-time data streams for transient and variability events, the accumulated data archive is a wealthy laboratory for making complementary scientific discoveries. The goal of this work is to optimise column-oriented database techniques to enable the construction of a full-source and light-curve database for large-scale surveys, that is accessible by the astronomical community. We adopted LOFAR's Transients Pipeline as the baseline and modified it to enable the processing of optical images that have much higher source densities. The pipeline adds new source lists to the archive database, while cross-matching them with the known cataloguedsources in order to build a full light-curve archive. We investigated several techniques of indexing and partitioning the largest tables, allowing for faster positional source look-ups in the cross matching algorithms. We monitored all query run times in long-term pipeline runs where we processed a subset of IPHAS data that have image source density peaks over 170,000 per field of view (500,000 deg-2). Our analysis demonstrates that horizontal table partitions of declination widths of one-degree control the query run times. Usage of an index strategy where the partitions are densely sorted according to source declination yields another improvement. Most queries run in sublinear time and a few (< 20%) run in linear time, because of dependencies on input source-list and result-set size. We observed that for this logical database partitioning schema the limiting cadence the pipeline achieved with processing IPHAS data is 25 s.
Disruptive technology for vector control: the Innovative Vector Control Consortium and the US Military join forces to explore transformative insecticide application technology for mosquito control programmes.

PubMed

Knapp, Jennifer; Macdonald, Michael; Malone, David; Hamon, Nicholas; Richardson, Jason H

2015-09-26

Malaria vector control technology has remained largely static for decades and there is a pressing need for innovative control tools and methodology to radically improve the quality and efficiency of current vector control practices. This report summarizes a workshop jointly organized by the Innovative Vector Control Consortium (IVCC) and the Armed Forces Pest Management Board (AFPMB) focused on public health pesticide application technology. Three main topics were discussed: the limitations with current tools and techniques used for indoor residual spraying (IRS), technology innovation to improve efficacy of IRS programmes, and truly disruptive application technology beyond IRS. The group identified several opportunities to improve application technology to include: insuring all IRS programmes are using constant flow valves and erosion resistant tips; introducing compression sprayer improvements that help minimize pesticide waste and human error; and moving beyond IRS by embracing the potential for new larval source management techniques and next generation technology such as unmanned "smart" spray systems. The meeting served to lay the foundation for broader collaboration between the IVCC and AFPMB and partners in industry, the World Health Organization, the Bill and Melinda Gates Foundation and others.
Study of Radio sources and interferences detected by MEXART

NASA Astrophysics Data System (ADS)

Villanueva Hernandez, P.; Gonzalez Esparza, J. A.; Carrillo, A.; Andrade, E.; Jeyacumar, S.; Kurtz, S.

2007-05-01

The Mexican Array Radio Telescope (MEXART) is a radio telescope that will perform studies of solar wind disturbances using the Interplanetary Scintillation (IPS) technique. The radiotelescope is its final calibration stage, and in this work we report two testings: the interference signals detected around the operation frequency, and the transit of the main radio sources detected by individual lines of 64 dipoles. These radio sources are: Sun, Casiopea, Crab nebula, Cygnus and Virgo. These testings allow us to know the response of the array elements in order to calibrate them. The final operation of the MEXART requires that the signal detected and transmitted by each East-West line of 64 dipoles arrives at the butler matrix (control room) with the same phase and amplitude.
A review on automated sorting of source-separated municipal solid waste for recycling.

PubMed

Gundupalli, Sathish Paulraj; Hait, Subrata; Thakur, Atul

2017-02-01

A crucial prerequisite for recycling forming an integral part of municipal solid waste (MSW) management is sorting of useful materials from source-separated MSW. Researchers have been exploring automated sorting techniques to improve the overall efficiency of recycling process. This paper reviews recent advances in physical processes, sensors, and actuators used as well as control and autonomy related issues in the area of automated sorting and recycling of source-separated MSW. We believe that this paper will provide a comprehensive overview of the state of the art and will help future system designers in the area. In this paper, we also present research challenges in the field of automated waste sorting and recycling. Copyright © 2016 Elsevier Ltd. All rights reserved.
Functional source separation and hand cortical representation for a brain–computer interface feature extraction

PubMed Central

Tecchio, Franca; Porcaro, Camillo; Barbati, Giulia; Zappasodi, Filippo

2007-01-01

A brain–computer interface (BCI) can be defined as any system that can track the person's intent which is embedded in his/her brain activity and, from it alone, translate the intention into commands of a computer. Among the brain signal monitoring systems best suited for this challenging task, electroencephalography (EEG) and magnetoencephalography (MEG) are the most realistic, since both are non-invasive, EEG is portable and MEG could provide more specific information that could be later exploited also through EEG signals. The first two BCI steps require set up of the appropriate experimental protocol while recording the brain signal and then to extract interesting features from the recorded cerebral activity. To provide information useful in these BCI stages, our aim is to provide an overview of a new procedure we recently developed, named functional source separation (FSS). As it comes from the blind source separation algorithms, it exploits the most valuable information provided by the electrophysiological techniques, i.e. the waveform signal properties, remaining blind to the biophysical nature of the signal sources. FSS returns the single trial source activity, estimates the time course of a neuronal pool along different experimental states on the basis of a specific functional requirement in a specific time period, and uses the simulated annealing as the optimization procedure allowing the exploit of functional constraints non-differentiable. Moreover, a minor section is included, devoted to information acquired by MEG in stroke patients, to guide BCI applications aiming at sustaining motor behaviour in these patients. Relevant BCI features – spatial and time-frequency properties – are in fact altered by a stroke in the regions devoted to hand control. Moreover, a method to investigate the relationship between sensory and motor hand cortical network activities is described, providing information useful to develop BCI feedback control systems. This review provides a description of the FSS technique, a promising tool for the BCI community for online electrophysiological feature extraction, and offers interesting information to develop BCI applications to sustain hand control in stroke patients. PMID:17331989
Design of system calibration for effective imaging

NASA Astrophysics Data System (ADS)

Varaprasad Babu, G.; Rao, K. M. M.

2006-12-01

A CCD based characterization setup comprising of a light source, CCD linear array, Electronics for signal conditioning/ amplification, PC interface has been developed to generate images at varying densities and at multiple view angles. This arrangement is used to simulate and evaluate images by Super Resolution technique with multiple overlaps and yaw rotated images at different view angles. This setup also generates images at different densities to analyze the response of the detector port wise separately. The light intensity produced by the source needs to be calibrated for proper imaging by the high sensitive CCD detector over the FOV. One approach is to design a complex integrating sphere arrangement which costs higher for such applications. Another approach is to provide a suitable intensity feed back correction wherein the current through the lamp is controlled in a closed loop arrangement. This method is generally used in the applications where the light source is a point source. The third method is to control the time of exposure inversely to the lamp variations where lamp intensity is not possible to control. In this method, light intensity during the start of each line is sampled and the correction factor is applied for the full line. The fourth method is to provide correction through Look Up Table where the response of all the detectors are normalized through the digital transfer function. The fifth method is to have a light line arrangement where the light through multiple fiber optic cables are derived from a single source and arranged them in line. This is generally applicable and economical for low width cases. In our applications, a new method wherein an inverse multi density filter is designed which provides an effective calibration for the full swath even at low light intensities. The light intensity along the length is measured, an inverse density is computed, a correction filter is generated and implemented in the CCD based Characterization setup. This paper describes certain novel techniques of design and implementation of system calibration for effective Imaging to produce better quality data product especially while handling high resolution data.
A constrained joint source/channel coder design and vector quantization of nonstationary sources

NASA Technical Reports Server (NTRS)

Sayood, Khalid; Chen, Y. C.; Nori, S.; Araj, A.

1993-01-01

The emergence of broadband ISDN as the network for the future brings with it the promise of integration of all proposed services in a flexible environment. In order to achieve this flexibility, asynchronous transfer mode (ATM) has been proposed as the transfer technique. During this period a study was conducted on the bridging of network transmission performance and video coding. The successful transmission of variable bit rate video over ATM networks relies on the interaction between the video coding algorithm and the ATM networks. Two aspects of networks that determine the efficiency of video transmission are the resource allocation algorithm and the congestion control algorithm. These are explained in this report. Vector quantization (VQ) is one of the more popular compression techniques to appear in the last twenty years. Numerous compression techniques, which incorporate VQ, have been proposed. While the LBG VQ provides excellent compression, there are also several drawbacks to the use of the LBG quantizers including search complexity and memory requirements, and a mismatch between the codebook and the inputs. The latter mainly stems from the fact that the VQ is generally designed for a specific rate and a specific class of inputs. In this work, an adaptive technique is proposed for vector quantization of images and video sequences. This technique is an extension of the recursively indexed scalar quantization (RISQ) algorithm.
Evaluating the Acoustic Effect of Over-the-Rotor Foam-Metal Liner Installed on a Low Speed Fan Using Virtual Rotating Microphone Imaging

NASA Technical Reports Server (NTRS)

Sutliff, Daniel L.; Dougherty, Robert P.; Walker, Bruce E.

2010-01-01

An in-duct beamforming technique for imaging rotating broadband fan sources has been used to evaluate the acoustic characteristics of a Foam-Metal Liner installed over-the-rotor of a low-speed fan. The NASA Glenn Research Center s Advanced Noise Control Fan was used as a test bed. A duct wall-mounted phased array consisting of several rings of microphones was employed. The data are mathematically resampled in the fan rotating reference frame and subsequently used in a conventional beamforming technique. The steering vectors for the beamforming technique are derived from annular duct modes, so that effects of reflections from the duct walls are reduced.
Distance-Based Behaviors for Low-Complexity Control in Multiagent Robotics

NASA Astrophysics Data System (ADS)

Pierpaoli, Pietro

Several biological examples show that living organisms cooperate to collectively accomplish tasks impossible for single individuals. More importantly, this coordination is often achieved with a very limited set of information. Inspired by these observations, research on autonomous systems has focused on the development of distributed control techniques for control and guidance of groups of autonomous mobile agents, or robots. From an engineering perspective, when coordination and cooperation is sought in large ensembles of robotic vehicles, a reduction in hardware and algorithms' complexity becomes mandatory from the very early stages of the project design. The research for solutions capable of lowering power consumption, cost and increasing reliability are thus worth investigating. In this work, we studied low-complexity techniques to achieve cohesion and control on swarms of autonomous robots. Starting from an inspiring example with two-agents, we introduced effects of neighbors' relative positions on control of an autonomous agent. The extension of this intuition addressed the control of large ensembles of autonomous vehicles, and was applied in the form of a herding-like technique. To this end, a low-complexity distance-based aggregation protocol was defined. We first showed that our protocol produced a cohesion aggregation among the agent while avoiding inter-agent collisions. Then, a feedback leader-follower architecture was introduced for the control of the swarm. We also described how proximity measures and probability of collisions with neighbors can also be used as source of information in highly populated environments.
Spreadsheet WATERSHED modeling for nonpoint-source pollution management in a Wisconsin basin

USGS Publications Warehouse

Walker, J.F.; Pickard, S.A.; Sonzogni, W.C.

1989-01-01

Although several sophisticated nonpoint pollution models exist, few are available that are easy to use, cover a variety of conditions, and integrate a wide range of information to allow managers and planners to assess different control strategies. Here, a straightforward pollutant input accounting approach is presented in the form of an existing model (WATERSHED) that has been adapted to run on modern electronic spreadsheets. As an application, WATERSHED is used to assess options to improve the quality of highly eutrophic Delavan Lake in Wisconsin. WATERSHED is flexible in that several techniques, such as the Universal Soil Loss Equation or unit-area loadings, can be used to estimate nonpoint-source inputs. Once the model parameters are determined (and calibrated, if possible), the spreadsheet features can be used to conduct a sensitivity analysis of management options. In the case of Delavan Lake, it was concluded that, although some nonpoint controls were cost-effective, the overall reduction in phosphorus would be insufficient to measurably improve water quality.A straightforward pollutant input accounting approach is presented in the form of an existing model (WATERSHED) that has been adapted to run on modern electronic spreadsheets. As an application, WATERSHED is used to assess options to improve the quality of highly eutrophic Delavan Lake in Wisconsin. WATERSHED is flexible in that several techniques, such as the Universal Soil Loss Equation or unit-area loadings, can be used to estimate nonpoint-source inputs. Once the model parameters are determined (and calibrated, if possible), the spreadsheet features can be used to conduct a sensitivity analysis of management options. In the case of Delavan Lake, it was concluded that, although some nonpoint controls were cost-effective, the overall reduction in phosphorus would be insufficient to measurably improve water quality.
Perceptually controlled doping for audio source separation

NASA Astrophysics Data System (ADS)

Mahé, Gaël; Nadalin, Everton Z.; Suyama, Ricardo; Romano, João MT

2014-12-01

The separation of an underdetermined audio mixture can be performed through sparse component analysis (SCA) that relies however on the strong hypothesis that source signals are sparse in some domain. To overcome this difficulty in the case where the original sources are available before the mixing process, the informed source separation (ISS) embeds in the mixture a watermark, which information can help a further separation. Though powerful, this technique is generally specific to a particular mixing setup and may be compromised by an additional bitrate compression stage. Thus, instead of watermarking, we propose a `doping' method that makes the time-frequency representation of each source more sparse, while preserving its audio quality. This method is based on an iterative decrease of the distance between the distribution of the signal and a target sparse distribution, under a perceptual constraint. We aim to show that the proposed approach is robust to audio coding and that the use of the sparsified signals improves the source separation, in comparison with the original sources. In this work, the analysis is made only in instantaneous mixtures and focused on voice sources.
Acoustic emission source location in complex structures using full automatic delta T mapping technique

NASA Astrophysics Data System (ADS)

Al-Jumaili, Safaa Kh.; Pearson, Matthew R.; Holford, Karen M.; Eaton, Mark J.; Pullin, Rhys

2016-05-01

An easy to use, fast to apply, cost-effective, and very accurate non-destructive testing (NDT) technique for damage localisation in complex structures is key for the uptake of structural health monitoring systems (SHM). Acoustic emission (AE) is a viable technique that can be used for SHM and one of the most attractive features is the ability to locate AE sources. The time of arrival (TOA) technique is traditionally used to locate AE sources, and relies on the assumption of constant wave speed within the material and uninterrupted propagation path between the source and the sensor. In complex structural geometries and complex materials such as composites, this assumption is no longer valid. Delta T mapping was developed in Cardiff in order to overcome these limitations; this technique uses artificial sources on an area of interest to create training maps. These are used to locate subsequent AE sources. However operator expertise is required to select the best data from the training maps and to choose the correct parameter to locate the sources, which can be a time consuming process. This paper presents a new and improved fully automatic delta T mapping technique where a clustering algorithm is used to automatically identify and select the highly correlated events at each grid point whilst the "Minimum Difference" approach is used to determine the source location. This removes the requirement for operator expertise, saving time and preventing human errors. A thorough assessment is conducted to evaluate the performance and the robustness of the new technique. In the initial test, the results showed excellent reduction in running time as well as improved accuracy of locating AE sources, as a result of the automatic selection of the training data. Furthermore, because the process is performed automatically, this is now a very simple and reliable technique due to the prevention of the potential source of error related to manual manipulation.
Movable-molybdenum-reflector reactivity experiments for control studies of compact space power reactor concepts

NASA Technical Reports Server (NTRS)

Fox, T. A.

1973-01-01

An experimental reflector reactivity study was made with a compact cylindrical reactor using a uranyl fluoride - water fuel solution. The reactor was axially unreflected and radially reflected with segments of molybdenum. The reflector segments were displaced incrementally in both the axial and radial dimensions, and the shutdown of each configuration was measured by using the pulsed-neutron source technique. The reactivity effects for axial and radial displacement of reflector segments are tabulated separately and compared. The experiments provide data for control-system studies of compact-space-power-reactor concepts.
Source And Sink Of Iodine For Drinking Water

NASA Technical Reports Server (NTRS)

Sauer, Richard L.; Flanagan, David T.; Gibbons, Randall E.

1991-01-01

Proposed system for controlling concentration of iodine in potable water exploits temperature dependence of equilibrium partition of iodine between solution in water and residence in ion-exchange resin. Used to maintain concentration of iodine sufficient to kill harmful microbes, but not so great to make water unpalatable. Requires little attention, yet controls concentration of iodine more precisely than iodination and deiodination by manual techniques. Conceived for use aboard spacecraft, system has terrestrial applications in regions where water must be kept potable, resupply difficult, and system must operate largely unattended.
Frequency division multiplex technique

NASA Technical Reports Server (NTRS)

Brey, H. (Inventor)

1973-01-01

A system for monitoring a plurality of condition responsive devices is described. It consists of a master control station and a remote station. The master control station is capable of transmitting command signals which includes a parity signal to a remote station which transmits the signals back to the command station so that such can be compared with the original signals in order to determine if there are any transmission errors. The system utilizes frequency sources which are 1.21 multiples of each other so that no linear combination of any harmonics will interfere with another frequency.
Control strategy based on SPWM switching patterns for grid connected photovoltaic inverter

NASA Astrophysics Data System (ADS)

Hassaine, L.; Mraoui, A.

2017-02-01

Generally, for lower installation of photovoltaic systems connected to the grid, pulse width modulation (PWM) is a widely used technique for controlling the voltage source inverters injects currents into the grid. The current injected must be sinusoidal with reduced harmonic distortion. In this paper, a digital implementation of a control strategy based on PWM switching patterns for an inverter for photovoltaic system connected to the grid is presented. This strategy synchronize a sinusoidal inverter output current with a grid voltage The digital implementation of the proposed PWM switching pattern when is compared with the conventional one exhibit the advantage: Simplicity, reduction of the memory requirements and power calculation for the control
Measuring trace gas emission from multi-distributed sources using vertical radial plume mapping (VRPM) and backward Lagrangian stochastic (bLS) techniques

USDA-ARS?s Scientific Manuscript database

Two micrometeorological techniques for measuring trace gas emission rates from distributed area sources were evaluated using a variety of synthetic area sources. The accuracy of the vertical radial plume mapping (VRPM) and the backward Lagrangian (bLS) techniques with an open-path optical spectrosco...
Bi-Frequency Modulated Quasi-Resonant Converters: Theory and Applications

NASA Astrophysics Data System (ADS)

Zhang, Yuefeng

1995-01-01

To avoid the variable frequency operation of quasi -resonant converters, many soft-switching PWM converters have been proposed, all of them require an auxiliary switch, which will increase the cost and complexity of the power supply system. In this thesis, a new kind of technique for quasi -resonant converters has been proposed, which is called the bi-frequency modulation technique. By operating the quasi-resonant converters at two switching frequencies, this technique enables quasi-resonant converters to achieve the soft-switching, at fixed switching frequencies, without an auxiliary switch. The steady-state analysis of four commonly used quasi-resonant converters, namely, ZVS buck, ZCS buck, ZVS boost, and ZCS boost converter has been presented. Using the concepts of equivalent sources, equivalent sinks, and resonant tank, the large signal models of these four quasi -resonant converters were developed. Based on these models, the steady-state control characteristics of BFM ZVS buck, BFM ZCS buck, BFM ZVS boost, and BFM ZCS boost converter have been derived. The functional block and design consideration of the bi-frequency controller were presented, and one of the implementations of the bi-frequency controller was given. A complete design example has been presented. Both computer simulations and experimental results have verified that the bi-frequency modulated quasi-resonant converters can achieve soft-switching, at fixed switching frequencies, without an auxiliary switch. One of the application of bi-frequency modulation technique is for EMI reduction. The basic principle of using BFM technique for EMI reduction was introduced. Based on the spectral analysis, the EMI performances of the PWM, variable-frequency, and bi-frequency modulated control signals was evaluated, and the BFM control signals show the lowest EMI emission. The bi-frequency modulated technique has also been applied to the power factor correction. A BFM zero -current switching boost converter has been designed for the power factor correction, and the simulation results show that the power factor has been improved.

Enhancing Self-Efficacy and Performance: An Experimental Comparison of Psychological Techniques.

PubMed

Wright, Bradley James; O'Halloran, Paul Daniel; Stukas, Arthur Anthony

2016-01-01

We assessed how 6 psychological performance enhancement techniques (PETs) differentially improved self-efficacy (SE) and skill performance. We also assessed whether vicarious experiences and verbal persuasion as posited sources of SE (Bandura, 1982 ) were supported and, further, if the effects of the 6 PETs remained after controlling for achievement motivation traits and self-esteem. A within-subject design assessed each individual across 2 trials for 3 disparate PETs. A between-groups design assessed differences between PETs paired against each other for 3 similar novel tasks. Participants (N = 96) performed 2 trials of 10 attempts at each of the tasks (kick, throw, golf putt) in a counterbalanced sequence using their nondominant limb. Participants completed the Sport Orientation Questionnaire, Rosenberg Self-Esteem Scale, and General Self-Efficacy Scale and were randomly allocated to either the modeling or imagery, goal-setting or instructional self-statement, or knowledge-of-results or motivational feedback conditions aligned with each task. An instructional self-statement improved performance better than imagery, modeling, goal setting, and motivational and knowledge-of-results augmented feedback. Motivational auditory feedback most improved SE. Increased SE change scores were related to increased performance difference scores on all tasks after controlling for age, sex, achievement motivation, and self-esteem. Some sources of SE may be more influential than others on both SE and performance improvements. We provide partial support for the sources of SE proposed by Bandura's social-cognitive theory with verbal persuasion but not vicarious experiences improving SE.
Cuphea: a new plant source of medium-chain fatty acids.

PubMed

Graham, S A

1989-01-01

The plant genus Cuphea (family Lythraceae) promises to provide a new source of industrially and nutritionally important medium-chain fatty acids, especially of lauric acid now supplied exclusively by coconut and palm kernel oils from foreign sources. The seed lipids of Cuphea were first discovered in the 1960s to contain high percentages of several medium-chain fatty acids, including caprylic, capric, lauric, and myristic acid. Research is still in the early stages, but it is intensifying toward the goal of developing the genus into a new temperate climate crop for production of specialty oils. Given the diversity of Cuphea seed lipid composition and the wide ecological and distributional range of the genus, it may be possible to tailor crops to produce selected fatty acids on demand under a variety of growing conditions. Cuphea comprises about 260 species, most native to the New World tropics. Its morphology, classification, chromosome numbers, distribution, ecology, and folk uses are presented. Seed structure is described and seed lipid composition for 73 species is summarized. Problems in domestication and agronomic progress are reviewed. Knowledge of the biosynthetic mechanism controlling the lipids produced by Cuphea remains very limited. Future research in this area, and particularly successful employment of gene transfer techniques, may allow genes controlling the mechanism to be transferred to an already established seed oil producer such as rapeseed. Presently, both traditional plant breeding techniques and newer biotechnological methods are directed toward Cuphea oilseed development.
A 10-year observation of PM2.5-bound nickel in Xi’an, China: Effects of source control on its trend and associated health risks

NASA Astrophysics Data System (ADS)

Xu, Hongmei; Ho, Steven Sai Hang; Cao, Junji; Guinot, Benjamin; Kan, Haidong; Shen, Zhenxing; Ho, Kin Fai; Liu, Suixin; Zhao, Zhuzi; Li, Jianjun; Zhang, Ningning; Zhu, Chongshu; Zhang, Qian; Huang, Rujin

2017-01-01

This study presents the first long term (10-year period, 2004-2013) datasets of PM2.5-bound nickel (Ni) concentration obtained from the daily sample in urban of Xi’an, Northwestern China. The Ni concentration trend, pollution sources, and the potential health risks associated to Ni were investigated. The Ni concentrations increased from 2004 to 2008, but then decreased due to coal consumption reduction, energy structure reconstruction, tighter emission rules and the improvement of the industrial and motor vehicle waste control techniques. With the comparison of distributions between workday and non-workday periods, the effectiveness of local and regional air pollution control policies and contributions of hypothetical Ni sources (industrial and automobile exhausts) were evaluated, demonstrating the health benefits to the populations during the ten years. Mean Ni cancer risk was higher than the threshold value of 10-6, suggesting that carcinogenic Ni still was a concern to the residents. Our findings conclude that there are still needs to establish more strict strategies and guidelines for atmospheric Ni in our living area, assisting to balance the relationship between economic growth and environmental conservation in China.
Efficient Privacy-Aware Record Integration.

PubMed

Kuzu, Mehmet; Kantarcioglu, Murat; Inan, Ali; Bertino, Elisa; Durham, Elizabeth; Malin, Bradley

2013-01-01

The integration of information dispersed among multiple repositories is a crucial step for accurate data analysis in various domains. In support of this goal, it is critical to devise procedures for identifying similar records across distinct data sources. At the same time, to adhere to privacy regulations and policies, such procedures should protect the confidentiality of the individuals to whom the information corresponds. Various private record linkage (PRL) protocols have been proposed to achieve this goal, involving secure multi-party computation (SMC) and similarity preserving data transformation techniques. SMC methods provide secure and accurate solutions to the PRL problem, but are prohibitively expensive in practice, mainly due to excessive computational requirements. Data transformation techniques offer more practical solutions, but incur the cost of information leakage and false matches. In this paper, we introduce a novel model for practical PRL, which 1) affords controlled and limited information leakage, 2) avoids false matches resulting from data transformation. Initially, we partition the data sources into blocks to eliminate comparisons for records that are unlikely to match. Then, to identify matches, we apply an efficient SMC technique between the candidate record pairs. To enable efficiency and privacy, our model leaks a controlled amount of obfuscated data prior to the secure computations. Applied obfuscation relies on differential privacy which provides strong privacy guarantees against adversaries with arbitrary background knowledge. In addition, we illustrate the practical nature of our approach through an empirical analysis with data derived from public voter records.
Simple, inexpensive technique for high-quality smartphone fundus photography in human and animal eyes.

PubMed

Haddock, Luis J; Kim, David Y; Mukai, Shizuo

2013-01-01

Purpose. We describe in detail a relatively simple technique of fundus photography in human and rabbit eyes using a smartphone, an inexpensive app for the smartphone, and instruments that are readily available in an ophthalmic practice. Methods. Fundus images were captured with a smartphone and a 20D lens with or without a Koeppe lens. By using the coaxial light source of the phone, this system works as an indirect ophthalmoscope that creates a digital image of the fundus. The application whose software allows for independent control of focus, exposure, and light intensity during video filming was used. With this app, we recorded high-definition videos of the fundus and subsequently extracted high-quality, still images from the video clip. Results. The described technique of smartphone fundus photography was able to capture excellent high-quality fundus images in both children under anesthesia and in awake adults. Excellent images were acquired with the 20D lens alone in the clinic, and the addition of the Koeppe lens in the operating room resulted in the best quality images. Successful photodocumentation of rabbit fundus was achieved in control and experimental eyes. Conclusion. The currently described system was able to take consistently high-quality fundus photographs in patients and in animals using readily available instruments that are portable with simple power sources. It is relatively simple to master, is relatively inexpensive, and can take advantage of the expanding mobile-telephone networks for telemedicine.
Topography of activation deficits in schizophrenia during P300 task related to cognition and structural connectivity.

PubMed

Molina, Vicente; Bachiller, Alejandro; de Luis, Rodrigo; Lubeiro, Alba; Poza, Jesús; Hornero, Roberto; Alonso, Joan Francesc; Mañanas, Miguel Angel; Marqués, Patricia; Romero, Sergio

2018-02-02

The study of cerebral underpinnings of schizophrenia may benefit from the high temporal resolution of electromagnetic techniques, but its spatial resolution is low. However, source imaging approaches such as low-resolution brain electromagnetic tomography (LORETA) allow for an acceptable compromise between spatial and temporal resolutions. We combined LORETA with 32 channels and 3-Tesla diffusion magnetic resonance (Dmr) to study cerebral dysfunction in 38 schizophrenia patients (17 first episodes, FE), compared to 53 healthy controls. The EEG was acquired with subjects performing an odd-ball task. Analyses included an adaptive window of interest to take into account the interindividual variability of P300 latency. We compared source activation patters to distractor (P3a) and target (P3b) tones within- and between-groups. Patients showed a reduced activation in anterior cingulate and lateral and medial prefrontal cortices, as well as inferior/orbital frontal regions. This was also found in the FE patients alone. The activation was directly related to IQ in the patients and controls and to working memory performance in controls. Symptoms were unrelated to source activation. Fractional anisotropy in the tracts connecting lateral prefrontal and anterior cingulate regions predicted source activation in these regions in the patients. These results replicate the source activation deficit found in a previous study with smaller sample size and a lower number of sensors and suggest an association between structural connectivity deficits and functional alterations.
Source-space ICA for MEG source imaging.

PubMed

Jonmohamadi, Yaqub; Jones, Richard D

2016-02-01

One of the most widely used approaches in electroencephalography/magnetoencephalography (MEG) source imaging is application of an inverse technique (such as dipole modelling or sLORETA) on the component extracted by independent component analysis (ICA) (sensor-space ICA + inverse technique). The advantage of this approach over an inverse technique alone is that it can identify and localize multiple concurrent sources. Among inverse techniques, the minimum-variance beamformers offer a high spatial resolution. However, in order to have both high spatial resolution of beamformer and be able to take on multiple concurrent sources, sensor-space ICA + beamformer is not an ideal combination. We propose source-space ICA for MEG as a powerful alternative approach which can provide the high spatial resolution of the beamformer and handle multiple concurrent sources. The concept of source-space ICA for MEG is to apply the beamformer first and then singular value decomposition + ICA. In this paper we have compared source-space ICA with sensor-space ICA both in simulation and real MEG. The simulations included two challenging scenarios of correlated/concurrent cluster sources. Source-space ICA provided superior performance in spatial reconstruction of source maps, even though both techniques performed equally from a temporal perspective. Real MEG from two healthy subjects with visual stimuli were also used to compare performance of sensor-space ICA and source-space ICA. We have also proposed a new variant of minimum-variance beamformer called weight-normalized linearly-constrained minimum-variance with orthonormal lead-field. As sensor-space ICA-based source reconstruction is popular in EEG and MEG imaging, and given that source-space ICA has superior spatial performance, it is expected that source-space ICA will supersede its predecessor in many applications.
Controlling chaotic behavior in CO2 and other lasers

NASA Astrophysics Data System (ADS)

1993-06-01

Additional substantial experimental progress has been made, in the third month of the project, in setting up equipment and testing for producing chaotic behavior with a CO2 laser. The project goal is to synchronize and control chaos in CO2 and other lasers, and thereby increase the power in ensembles of coupled laser sources. Numerous investigations into the chaos regime have been made, a second CO2 laser has been brought on stream, and work is progressing in the fourth month toward coupling the two lasers and control of the first laser. It is also intended to submit at least two papers to the Second Experimental Chaos Conference which is supported by the Office of Naval Research. Abstracts to those two papers are attached. Last month's report discussed the experimental investigation of nonlinear dynamics of CO2 lasers which involved a new technique of inducing chaos. In this new technique, an acoustically modulated feedback of the laser light was used and led to chaotic dynamics at a very low modulation frequency of 375 Hz. Since then, new results have been obtained by an Electro-Optical Modulation (EOM) technique. In the new setup, the electro-optical modulator is placed in an external cavity outside the laser.
The validation of the Z-Scan technique for the determination of plasma glucose

NASA Astrophysics Data System (ADS)

Alves, Sarah I.; Silva, Elaine A. O.; Costa, Simone S.; Sonego, Denise R. N.; Hallack, Maira L.; Coppini, Ornela L.; Rowies, Fernanda; Azzalis, Ligia A.; Junqueira, Virginia B. C.; Pereira, Edimar C.; Rocha, Katya C.; Fonseca, Fernando L. A.

2013-11-01

Glucose is the main energy source for the human body. The concentration of blood glucose is regulated by several hormones including both antagonists: insulin and glucagon. The quantification of glucose in the blood is used for diagnosing metabolic disorders of carbohydrates, such as diabetes, idiopathic hypoglycemia and pancreatic diseases. Currently, the methodology used for this determination is the enzymatic colorimetric with spectrophotometric. This study aimed to validate the use of measurements of nonlinear optical properties of plasma glucose via the Z-Scan technique. For this we used samples of calibrator patterns that simulate commercial samples of patients (ELITech ©). Besides calibrators, serum glucose levels within acceptable reference values (normal control serum - Brazilian Society of Clinical Pathology and Laboratory Medicine) and also overestimated (pathological control serum - Brazilian Society of Clinical Pathology and Laboratory Medicine) were used in the methodology proposal. Calibrator dilutions were performed and determined by the Z-Scan technique for the preparation of calibration curve. In conclusion, Z-Scan method can be used to determinate glucose levels in biological samples with enzymatic colorimetric reaction and also to apply the same quality control parameters used in biochemistry clinical.
A Review of Distributed Control Techniques for Power Quality Improvement in Micro-grids

NASA Astrophysics Data System (ADS)

Zeeshan, Hafiz Muhammad Ali; Nisar, Fatima; Hassan, Ahmad

2017-05-01

Micro-grid is typically visualized as a small scale local power supply network dependent on distributed energy resources (DERs) that can operate simultaneously with grid as well as in standalone manner. The distributed generator of a micro-grid system is usually a converter-inverter type topology acting as a non-linear load, and injecting harmonics into the distribution feeder. Hence, the negative effects on power quality by the usage of distributed generation sources and components are clearly witnessed. In this paper, a review of distributed control approaches for power quality improvement is presented which encompasses harmonic compensation, loss mitigation and optimum power sharing in multi-source-load distributed power network. The decentralized subsystems for harmonic compensation and active-reactive power sharing accuracy have been analysed in detail. Results have been validated to be consistent with IEEE standards.
Robotic vision. [process control applications

NASA Technical Reports Server (NTRS)

Williams, D. S.; Wilf, J. M.; Cunningham, R. T.; Eskenazi, R.

1979-01-01

Robotic vision, involving the use of a vision system to control a process, is discussed. Design and selection of active sensors employing radiation of radio waves, sound waves, and laser light, respectively, to light up unobservable features in the scene are considered, as are design and selection of passive sensors, which rely on external sources of illumination. The segmentation technique by which an image is separated into different collections of contiguous picture elements having such common characteristics as color, brightness, or texture is examined, with emphasis on the edge detection technique. The IMFEX (image feature extractor) system performing edge detection and thresholding at 30 frames/sec television frame rates is described. The template matching and discrimination approach to recognize objects are noted. Applications of robotic vision in industry for tasks too monotonous or too dangerous for the workers are mentioned.
Flux control coefficients determined by inhibitor titration: the design and analysis of experiments to minimize errors.

PubMed Central

Small, J R

1993-01-01

This paper is a study into the effects of experimental error on the estimated values of flux control coefficients obtained using specific inhibitors. Two possible techniques for analysing the experimental data are compared: a simple extrapolation method (the so-called graph method) and a non-linear function fitting method. For these techniques, the sources of systematic errors are identified and the effects of systematic and random errors are quantified, using both statistical analysis and numerical computation. It is shown that the graph method is very sensitive to random errors and, under all conditions studied, that the fitting method, even under conditions where the assumptions underlying the fitted function do not hold, outperformed the graph method. Possible ways of designing experiments to minimize the effects of experimental errors are analysed and discussed. PMID:8257434
IDENTIFICATION OF SOURCES OF GROUND-WATER SALINIZA- TION USING GEOCHEMICAL TECHNIQUES

EPA Science Inventory

This report deals with salt-water sources that commonly mix and deteriorate fresh ground water. It reviews characteristics of salt-water sources and geochemical techniques that can be used to identify these sources after mixing has occurred. The report is designed to assist inves...
The association of funding source on effect size in randomized controlled trials: 2013-2015 - a cross-sectional survey and meta-analysis.

PubMed

Falk Delgado, Alberto; Falk Delgado, Anna

2017-03-14

Trials financed by for-profit organizations have been associated with favorable outcomes of new treatments, although the effect size of funding source impact on outcome is unknown. The aim of this study was to estimate the effect size for a favorable outcome in randomized controlled trials (RCTs), stratified by funding source, that have been published in general medical journals. Parallel-group RCTs published in The Lancet, New England Journal of Medicine, and JAMA between 2013 and 2015 were identified. RCTs with binary primary endpoints were included. The primary outcome was the OR of patients' having a favorable outcome in the intervention group compared with the control group. The OR of a favorable outcome in each trial was calculated by the number of positive events that occurred in the intervention and control groups. A meta-analytic technique with random effects model was used to calculate summary OR. Data were stratified by funding source as for-profit, mixed, and nonprofit. Prespecified sensitivity, subgroup, and metaregression analyses were performed. Five hundred nine trials were included. The OR for a favorable outcome in for-profit-funded RCTs was 1.92 (95% CI 1.72-2.14), which was higher than mixed source-funded RCTs (OR 1.34, 95% CI 1.25-1.43) and nonprofit-funded RCTs (OR 1.32, 95% CI 1.26-1.39). The OR for a favorable outcome was higher for both clinical and surrogate endpoints in for-profit-funded trials than in RCTs with other funding sources. Excluding drug trials lowered the OR for a favorable outcome in for-profit-funded RCTs. The OR for a favorable surrogate outcome in drug trials was higher in for-profit-funded trials than in nonprofit-funded trials. For-profit-funded RCTs have a higher OR for a favorable outcome than nonprofit- and mixed source-funded RCTs. This difference is associated mainly with the use of surrogate endpoints in for-profit-financed drug trials.
Description of the SSF PMAD DC testbed control system data acquisition function

NASA Technical Reports Server (NTRS)

Baez, Anastacio N.; Mackin, Michael; Wright, Theodore

1992-01-01

The NASA LeRC in Cleveland, Ohio has completed the development and integration of a Power Management and Distribution (PMAD) DC Testbed. This testbed is a reduced scale representation of the end to end, sources to loads, Space Station Freedom Electrical Power System (SSF EPS). This unique facility is being used to demonstrate DC power generation and distribution, power management and control, and system operation techniques considered to be prime candidates for the Space Station Freedom. A key capability of the testbed is its ability to be configured to address system level issues in support of critical SSF program design milestones. Electrical power system control and operation issues like source control, source regulation, system fault protection, end-to-end system stability, health monitoring, resource allocation, and resource management are being evaluated in the testbed. The SSF EPS control functional allocation between on-board computers and ground based systems is evolving. Initially, ground based systems will perform the bulk of power system control and operation. The EPS control system is required to continuously monitor and determine the current state of the power system. The DC Testbed Control System consists of standard controllers arranged in a hierarchical and distributed architecture. These controllers provide all the monitoring and control functions for the DC Testbed Electrical Power System. Higher level controllers include the Power Management Controller, Load Management Controller, Operator Interface System, and a network of computer systems that perform some of the SSF Ground based Control Center Operation. The lower level controllers include Main Bus Switch Controllers and Photovoltaic Controllers. Power system status information is periodically provided to the higher level controllers to perform system control and operation. The data acquisition function of the control system is distributed among the various levels of the hierarchy. Data requirements are dictated by the control system algorithms being implemented at each level. A functional description of the various levels of the testbed control system architecture, the data acquisition function, and the status of its implementationis presented.
Modeling Pilot Pulse Control

NASA Technical Reports Server (NTRS)

Bachelder, Edward; Hess, Ronald; Godfroy-Cooper, Martine; Aponso, Bimal

2017-01-01

In this study, behavioral models are developed that closely reproduced pulsive control response of two pilots from the experimental pool using markedly different control techniques (styles) while conducting a tracking task. An intriguing find was that the pilots appeared to: 1) produce a continuous, internally-generated stick signal that they integrated in time; 2) integrate the actual stick position; and 3) compare the two integrations to issue and cease pulse commands. This suggests that the pilots utilized kinesthetic feedback in order to perceive and integrate stick position, supporting the hypothesis that pilots can access and employ the proprioceptive inner feedback loop proposed by Hess' pilot Structural Model. The Pulse Models used in conjunction with the pilot Structural Model closely recreated the pilot data both in the frequency and time domains during closed-loop simulation. This indicates that for the range of tasks and control styles encountered, the models captured the fundamental mechanisms governing pulsive and control processes. The pilot Pulse Models give important insight for the amount of remnant (stick output uncorrelated with the forcing function) that arises from nonlinear pilot technique, and for the remaining remnant arising from different sources unrelated to tracking control (i.e. neuromuscular tremor, reallocation of cognitive resources, etc.).
Effects of pre- and post-harvest site preparation treatments on natural regeneration success in a mixed hardwood stand after 10 years

Treesearch

Wayne K. Clatterbuck; Martin R. Schubert

2010-01-01

Advance regeneration, sprouts and seeds are sources of reproduction in the regeneration of mixed hardwood stands following harvest. The control of undesirable, non-commercial, competing vegetation is a common technique in site preparation to promote the establishment and growth of desirable species. This study was designed to evaluate the effectiveness of pre- and post...
40 CFR 141.135 - Treatment technique for control of disinfection byproduct (DBP) precursors.

Code of Federal Regulations, 2010 CFR

2010-07-01

... or enhanced softening to achieve the TOC percent removal levels specified in paragraph (b) of this... requirements in § 141.132(d). (i) The system's source water TOC level, measured according to § 141.131(d)(3... water TOC level, measured according to § 141.131(d)(3), is less than 2.0 mg/L, calculated quarterly as a...
Insider Threat Control: Using Plagiarism Detection Algorithms to Prevent Data Exfiltration in Near Real Time

DTIC Science & Technology

2013-10-01

Threats: Tools and Techniques 2 2.1 The Man-in-The-Middle ( MiTM ) Proxy 2 2.2 The Inspection Process 2 3 Installing WebDLPIndexer 4 3.1 Install JDK SE...selected open source and public-domain tools since they are freely available to the public. 2.1 The Man-in-The-Middle ( MiTM ) Proxy This report builds
Favorable toxicity and biochemical control using real-time inverse optimization technique for prostate brachytherapy.

PubMed

Raben, Adam; Rusthoven, Kyle E; Sarkar, Abrihup; Glick, Andrew; Benge, Bruce; Jacobs, Dayee; Raben, David

2009-01-01

Favorable dosimetric results have been reported using intraoperative inverse optimization (IO) for permanent prostate brachytherapy. The clinical implications of these improvements in dosimetry are unclear. We review toxicity and early biochemical outcomes for patients implanted using IO technique. Between 2001 and 2007, 165 patients received permanent prostate implants using real-time IO and had >/=3 months of followup. Dose constraints for inverse planning were: the prostate volume receiving 100% of the prescription dose [prostate V(100)] was >95%; the dose received by 90% of the gland [prostate D(90)] was within the 140-180 by dose range; the volume of urethra receiving 150% of the prescription dose [urethra V(150)] was <30%; and the volume of rectal wall receiving 110% of the prescription dose [rectal V(110)] was <1.0 cc. Toxicity was prospectively scored using the Radiation Therapy Oncology Group toxicity scale and the International Prostate Symptom Score questionnaire. Biochemical control was determined using the nadir + 2 ng/mL definition. Mean followup was 30 months (range, 6-63 months). Risk classification was low risk in 89% and intermediate risk in 11%. Iodine-125 sources were used for 161 implants and palladium-103 sources for four implants. The median number of seeds and total activity implanted were 61 and 999 MBq, respectively, for a median prostate volume of 33.6 cc. Late GU and GI morbidity was uncommon. Among patients with at least 24 months followup, 16% had persistent Grade 2-3 urinary morbidity. Grade 2 rectal bleeding occurred in 1 patient (0.6%). Biochemical failure has occurred in only 4 patients at last followup. IO technique for prostate brachytherapy is associated with low rates of late morbidity and excellent early biochemical control. Additionally, the number of seeds and total implanted activity required to achieve a high-quality implant are lower compared with historical controls.

In vivo quantitative imaging of point-like bioluminescent and fluorescent sources: Validation studies in phantoms and small animals post mortem

NASA Astrophysics Data System (ADS)

Comsa, Daria Craita

2008-10-01

There is a real need for improved small animal imaging techniques to enhance the development of therapies in which animal models of disease are used. Optical methods for imaging have been extensively studied in recent years, due to their high sensitivity and specificity. Methods like bioluminescence and fluorescence tomography report promising results for 3D reconstructions of source distributions in vivo. However, no standard methodology exists for optical tomography, and various groups are pursuing different approaches. In a number of studies on small animals, the bioluminescent or fluorescent sources can be reasonably approximated as point or line sources. Examples include images of bone metastases confined to the bone marrow. Starting with this premise, we propose a simpler, faster, and inexpensive technique to quantify optical images of point-like sources. The technique avoids the computational burden of a tomographic method by using planar images and a mathematical model based on diffusion theory. The model employs in situ optical properties estimated from video reflectometry measurements. Modeled and measured images are compared iteratively using a Levenberg-Marquardt algorithm to improve estimates of the depth and strength of the bioluminescent or fluorescent inclusion. The performance of the technique to quantify bioluminescence images was first evaluated on Monte Carlo simulated data. Simulated data also facilitated a methodical investigation of the effect of errors in tissue optical properties on the retrieved source depth and strength. It was found that, for example, an error of 4 % in the effective attenuation coefficient led to 4 % error in the retrieved depth for source depths of up to 12mm, while the error in the retrieved source strength increased from 5.5 % at 2mm depth, to 18 % at 12mm depth. Experiments conducted on images from homogeneous tissue-simulating phantoms showed that depths up to 10mm could be estimated within 8 %, and the relative source strength within 20 %. For sources 14mm deep, the inaccuracy in determining the relative source strength increased to 30 %. Measurements on small animals post mortem showed that the use of measured in situ optical properties to characterize heterogeneous tissue resulted in a superior estimation of the source strength and depth compared to when literature optical properties for organs or tissues were used. Moreover, it was found that regardless of the heterogeneity of the implant location or depth, our algorithm consistently showed an advantage over the simple assessment of the source strength based on the signal strength in the emission image. Our bioluminescence algorithm was generally able to predict the source strength within a factor of 2 of the true strength, but the performance varied with the implant location and depth. In fluorescence imaging a more complex technique is required, including knowledge of tissue optical properties at both the excitation and emission wavelengths. A theoretical study using simulated fluorescence data showed that, for example, for a source 5 mm deep in tissue, errors of up to 15 % in the optical properties would give rise to errors of +/-0.7 mm in the retrieved depth and the source strength would be over- or under-estimated by a factor ranging from 1.25 to 2. Fluorescent sources implanted in rats post mortem at the same depth were localized with an error just slightly higher than predicted theoretically: a root-mean-square value of 0.8 mm was obtained for all implants 5 mm deep. However, for this source depth, the source strength was assessed within a factor ranging from 1.3 to 4.2 from the value estimated in a controlled medium. Nonetheless, similarly to the bioluminescence study, the fluorescence quantification algorithm consistently showed an advantage over the simple assessment of the source strength based on the signal strength in the fluorescence image. Few studies have been reported in the literature that reconstruct known sources of bioluminescence or fluorescence in vivo or in heterogeneous phantoms. The few reported results show that the 3D tomographic methods have not yet reached their full potential. In this context, the simplicity of our technique emerges as a strong advantage.
Personal sound zone reproduction with room reflections

NASA Astrophysics Data System (ADS)

Olik, Marek

Loudspeaker-based sound systems, capable of a convincing reproduction of different audio streams to listeners in the same acoustic enclosure, are a convenient alternative to headphones. Such systems aim to generate "sound zones" in which target sound programmes are to be reproduced with minimum interference from any alternative programmes. This can be achieved with appropriate filtering of the source (loudspeaker) signals, so that the target sound's energy is directed to the chosen zone while being attenuated elsewhere. The existing methods are unable to produce the required sound energy ratio (acoustic contrast) between the zones with a small number of sources when strong room reflections are present. Optimization of parameters is therefore required for systems with practical limitations to improve their performance in reflective acoustic environments. One important parameter is positioning of sources with respect to the zones and room boundaries. The first contribution of this thesis is a comparison of the key sound zoning methods implemented on compact and distributed geometrical source arrangements. The study presents previously unpublished detailed evaluation and ranking of such arrangements for systems with a limited number of sources in a reflective acoustic environment similar to a domestic room. Motivated by the requirement to investigate the relationship between source positioning and performance in detail, the central contribution of this thesis is a study on optimizing source arrangements when strong individual room reflections occur. Small sound zone systems are studied analytically and numerically to reveal relationships between the geometry of source arrays and performance in terms of acoustic contrast and array effort (related to system efficiency). Three novel source position optimization techniques are proposed to increase the contrast, and geometrical means of reducing the effort are determined. Contrary to previously published case studies, this work presents a systematic examination of the key problem of first order reflections and proposes general optimization techniques, thus forming an important contribution. The remaining contribution considers evaluation and comparison of the proposed techniques with two alternative approaches to sound zone generation under reflective conditions: acoustic contrast control (ACC) combined with anechoic source optimization and sound power minimization (SPM). The study provides a ranking of the examined approaches which could serve as a guideline for method selection for rooms with strong individual reflections.
Damage source identification of reinforced concrete structure using acoustic emission technique.

PubMed

Panjsetooni, Alireza; Bunnori, Norazura Muhamad; Vakili, Amir Hossein

2013-01-01

Acoustic emission (AE) technique is one of the nondestructive evaluation (NDE) techniques that have been considered as the prime candidate for structural health and damage monitoring in loaded structures. This technique was employed for investigation process of damage in reinforced concrete (RC) frame specimens. A number of reinforced concrete RC frames were tested under loading cycle and were simultaneously monitored using AE. The AE test data were analyzed using the AE source location analysis method. The results showed that AE technique is suitable to identify the sources location of damage in RC structures.
Damage Source Identification of Reinforced Concrete Structure Using Acoustic Emission Technique

PubMed Central

Panjsetooni, Alireza; Bunnori, Norazura Muhamad; Vakili, Amir Hossein

2013-01-01

Acoustic emission (AE) technique is one of the nondestructive evaluation (NDE) techniques that have been considered as the prime candidate for structural health and damage monitoring in loaded structures. This technique was employed for investigation process of damage in reinforced concrete (RC) frame specimens. A number of reinforced concrete RC frames were tested under loading cycle and were simultaneously monitored using AE. The AE test data were analyzed using the AE source location analysis method. The results showed that AE technique is suitable to identify the sources location of damage in RC structures. PMID:23997681
Bioinspired large-scale aligned porous materials assembled with dual temperature gradients

PubMed Central

Bai, Hao; Chen, Yuan; Delattre, Benjamin; Tomsia, Antoni P.; Ritchie, Robert O.

2015-01-01

Natural materials, such as bone, teeth, shells, and wood, exhibit outstanding properties despite being porous and made of weak constituents. Frequently, they represent a source of inspiration to design strong, tough, and lightweight materials. Although many techniques have been introduced to create such structures, a long-range order of the porosity as well as a precise control of the final architecture remain difficult to achieve. These limitations severely hinder the scale-up fabrication of layered structures aimed for larger applications. We report on a bidirectional freezing technique to successfully assemble ceramic particles into scaffolds with large-scale aligned, lamellar, porous, nacre-like structure and long-range order at the centimeter scale. This is achieved by modifying the cold finger with a polydimethylsiloxane (PDMS) wedge to control the nucleation and growth of ice crystals under dual temperature gradients. Our approach could provide an effective way of manufacturing novel bioinspired structural materials, in particular advanced materials such as composites, where a higher level of control over the structure is required. PMID:26824062
Analysis and experimental evaluation of shunt active power filter for power quality improvement based on predictive direct power control.

PubMed

Aissa, Oualid; Moulahoum, Samir; Colak, Ilhami; Babes, Badreddine; Kabache, Nadir

2017-10-12

This paper discusses the use of the concept of classical and predictive direct power control for shunt active power filter function. These strategies are used to improve the active power filter performance by compensation of the reactive power and the elimination of the harmonic currents drawn by non-linear loads. A theoretical analysis followed by a simulation using MATLAB/Simulink software for the studied techniques has been established. Moreover, two test benches have been carried out using the dSPACE card 1104 for the classic and predictive DPC control to evaluate the studied methods in real time. Obtained results are presented and compared in this paper to confirm the superiority of the predictive technique. To overcome the pollution problems caused by the consumption of fossil fuels, renewable energies are the alternatives recommended to ensure green energy. In the same context, the tested predictive filter can easily be supplied by a renewable energy source that will give its impact to enhance the power quality.
Development of Real Time Implementation of 5/5 Rule based Fuzzy Logic Controller Shunt Active Power Filter for Power Quality Improvement

NASA Astrophysics Data System (ADS)

Puhan, Pratap Sekhar; Ray, Pravat Kumar; Panda, Gayadhar

2016-12-01

This paper presents the effectiveness of 5/5 Fuzzy rule implementation in Fuzzy Logic Controller conjunction with indirect control technique to enhance the power quality in single phase system, An indirect current controller in conjunction with Fuzzy Logic Controller is applied to the proposed shunt active power filter to estimate the peak reference current and capacitor voltage. Current Controller based pulse width modulation (CCPWM) is used to generate the switching signals of voltage source inverter. Various simulation results are presented to verify the good behaviour of the Shunt active Power Filter (SAPF) with proposed two levels Hysteresis Current Controller (HCC). For verification of Shunt Active Power Filter in real time, the proposed control algorithm has been implemented in laboratory developed setup in dSPACE platform.
WE-DE-201-08: Multi-Source Rotating Shield Brachytherapy Apparatus for Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dadkhah, H; Wu, X; Kim, Y

Purpose: To introduce a novel multi-source rotating shield brachytherapy (RSBT) apparatus for the precise simultaneous angular and linear positioning of all partially-shielded 153Gd radiation sources in interstitial needles for treating prostate cancer. The mechanism is designed to lower the detrimental dose to healthy tissues, the urethra in particular, relative to conventional high-dose-rate brachytherapy (HDR-BT) techniques. Methods: Following needle implantation, the delivery system is docked to the patient template. Each needle is coupled to a multi-source afterloader catheter by a connector passing through a shaft. The shafts are rotated by translating a moving template between two stationary templates. Shaft walls asmore » well as moving template holes are threaded such that the resistive friction produced between the two parts exerts enough force on the shafts to bring about the rotation. Rotation of the shaft is then transmitted to the shielded source via several keys. Thus, shaft angular position is fully correlated with the position of the moving template. The catheter angles are simultaneously incremented throughout treatment as needed, and only a single 360° rotation of all catheters is needed for a full treatment. For each rotation angle, source depth in each needle is controlled by a multi-source afterloader, which is proposed as an array of belt-driven linear actuators, each of which drives a source wire. Results: Optimized treatment plans based on Monte Carlo dose calculations demonstrated RSBT with the proposed apparatus reduced urethral D{sub 1cc} below that of conventional HDR-BT by 35% for urethral dose gradient volume within 3 mm of the urethra surface. Treatment time to deliver 20 Gy with multi-source RSBT apparatus using nineteen 62.4 GBq {sup 153}Gd sources is 117 min. Conclusions: The proposed RSBT delivery apparatus in conjunction with multiple nitinol catheter-mounted platinum-shielded {sup 153}Gd sources enables a mechanically feasible urethra-sparing treatment technique for prostate cancer in a clinically reasonable timeframe.« less
Applicability of geochemical techniques and artificial sweeteners in discriminating the anthropogenic sources of chloride in shallow groundwater north of Toronto, Canada.

PubMed

Khazaei, Esmaeil; Milne-Home, William

2017-05-01

Elevated levels of chloride concentration due to anthropogenic activities including the road salts, septic effluent and agricultural sources are common in shallow groundwater of the recent glacial deposits north of Toronto, Ontario, Canada. Identifying suitable techniques for discriminating the source of the chloride concentration helps to better plan the protection of groundwater in the area. This paper examines the applicability of geochemical techniques with emphasis on Panno et al. (Ground Water 44: 176-187, 2006) and Mullaney et al. (2009) graphical approaches for discriminating the sources of chloride with known causes of impacts. The results indicated that the graphical methods developed using Cl - , Br - and/or total nitrogen (N) could identify the combined sources of road salts and septic systems. However, discriminating between the road salts, septic effluent or agricultural sources needs to be complemented by other techniques including the artificial sweeteners and isotope tracers.
InGaAsP-based uni-travelling carrier photodiode structure grown by solid source molecular beam epitaxy.

PubMed

Natrella, Michele; Rouvalis, Efthymios; Liu, Chin-Pang; Liu, Huiyun; Renaud, Cyril C; Seeds, Alwyn J

2012-08-13

We report the first InGaAsP-based uni-travelling carrier photodiode structure grown by Solid Source Molecular Beam Epitaxy; the material contains layers of InGaAsP as thick as 300 nm and a 120 nm thick InGaAs absorber. Large area vertically illuminated test devices have been fabricated and characterised; the devices exhibited 0.1 A/W responsivity at 1550 nm, 12.5 GHz -3 dB bandwidth and -5.8 dBm output power at 10 GHz for a photocurrent of 4.8 mA. The use of Solid Source Molecular Beam Epitaxy enables the major issue associated with the unintentional diffusion of zinc in Metal Organic Vapour Phase Epitaxy to be overcome and gives the benefit of the superior control provided by MBE growth techniques without the costs and the risks of handling toxic gases of Gas Source Molecular Beam Epitaxy.
Lunar cartographic dossier, volume 1

NASA Technical Reports Server (NTRS)

Schimerman, L. A. (Editor)

1975-01-01

The dossier is designed to provide an up to date summary of the extent and quality of cartographic information as well as describing materials available to support lunar scientific investigation and study. It covers the specific photographic, selenodetic and cartographic data considered to be of continuing significance to users of lunar cartographic information. Historical background data is included. Descriptive and evaluative information is presented concerning lunar maps, photomaps and photo mosaics. Discussion comprises identification of series or individual sheet characteristics, control basis, source materials and compilation methodology used. The global, regional and local selenodetic control are described which were produced for lunar feature location in support of lunar mapping or positional study. Further discussion covers the fundamental basis for each control system, number of points produced, techniques employed and evaluated accuracy. Although lunar photography is an informational source rather than a cartographic product, a photography section was included to facilitate correlation to the mapping and control works described. Description of lunar photographic systems, photography and photo support data are presented from a cartographic-photogrammetric viewpoint with commentary on cartographic applications.
Sediment connectivity at source-bordering aeolian dunefields along the Colorado River in the Grand Canyon, USA

NASA Astrophysics Data System (ADS)

Sankey, Joel; Kasprak, Alan; Caster, Joshua; East, Amy; Fairley, Helen

2017-04-01

Aeolian dunefields that are primarily built and maintained with river-derived sediment are found in many river valleys throughout the world and are impacted by changes in climate, land use, and river regulation. Quantifying the dynamic response of these aeolian dunefields to alterations in river flow is especially difficult given the highly correlated nature of the interacting geomorphic and sediment transport processes that drive their formation and maintenance. We characterize the effects of controlled river floods on changes in sediment connectivity at source-bordering aeolian dunefields in the Grand Canyon, USA. Controlled floods from the Glen Canyon Dam are used to build sandbars along the Colorado River in Grand Canyon which provide the main sediment source for aeolian dunefields. Aeolian dunefields are a primary resource of concern for land managers in the Grand Canyon because they often contain buried archaeological features. To characterize dunefield response to controlled floods, we use a novel, automated approach for the mechanistic segregation of geomorphic change to discern the geomorphic processes responsible for driving topographic change in very high resolution digital elevation models-of-difference (DODs) that span multiple, consecutive controlled river floods at source-bordering dunefields. We subsequently compare the results of mechanistic segregation with modelled estimates of aeolian dunefield evolution in order to understand how dunefields respond to contemporary, anthropogenically-driven variability in sediment supply and connectivity. These methods provide a rapid technique for sediment budgeting and enable the inference of spatial and temporal patterns in sediment flux between the fluvial and aeolian domains. We anticipate that this approach will be adaptable to other river valleys where the interactions of aeolian, fluvial, and hillslope processes drive sediment connectivity for the maintenance of source-bordering aeolian dunefields.
100 years of seismic research on the Moho

NASA Astrophysics Data System (ADS)

Prodehl, Claus; Kennett, Brian; Artemieva, Irina M.; Thybo, Hans

2013-12-01

The detection of a seismic boundary, the “Moho”, between the outermost shell of the Earth, the Earth's crust, and the Earth's mantle by A. Mohorovičić was the consequence of increased insight into the propagation of seismic waves caused by earthquakes. This short history of seismic research on the Moho is primarily based on the comprehensive overview of the worldwide history of seismological studies of the Earth's crust using controlled sources from 1850 to 2005, by Prodehl and Mooney (2012). Though the art of applying explosions, so-called “artificial events”, as energy sources for studies of the uppermost crustal layers began in the early 1900s, its effective use for studying the entire crust only began at the end of World War II. From 1945 onwards, controlled-source seismology has been the major approach to study details of the crust and underlying crust-mantle boundary, the Moho. The subsequent description of history of controlled-source crustal seismology and its seminal results is subdivided into separate chapters for each decade, highlighting the major advances achieved during that decade in terms of data acquisition, processing technology, and interpretation methods. Since the late 1980s, passive seismology using distant earthquakes has played an increasingly important role in studies of crustal structure. The receiver function technique exploiting conversions between P and SV waves at discontinuities in seismic wavespeed below a seismic station has been extensively applied to the increasing numbers of permanent and portable broad-band seismic stations across the globe. Receiver function studies supplement controlled source work with improved geographic coverage and now make a significant contribution to knowledge of the nature of the crust and the depth to Moho.
Centers for Disease Control and Prevention injury research agenda: identification of acute care research topics of interest to the Centers for disease Control and Prevention--National Center for Injury Prevention and Control.

PubMed

Jurkovich, Gregory J; Rivara, Frederick P; Johansen, Jennifer M; Maier, Ronald V

2004-05-01

The purpose of this report is to identify the most important research questions pertaining to the acute care of the injured patient using a Web-based Delphi technique to achieve expert opinion consensus. Experts in trauma care from the United States and Canada (n =39) generated structured research questions and then ranked these questions in order of importance, using a Web-based survey for question generation, question ranking, and a Delphi technique of consensus. Guidelines for question construction and ranking specified that participants considered questions that fall within the interest and domain of the Centers for Disease Control (CDC)-National Center for Injury Prevention and Control (NCIPC). One hundred thirty-seven questions in 18 distinct categories of interest were initially generated. After two rounds of merging, collating, reassessing, and ranking by significance and importance, 25 research questions were deemed most important and significant in the care of the injured patient. Ten of these (40%) were considered to be appropriate issues for the CDC-NCIPC to address and fund, dealing with injury prevention strategies, trauma systems design and funding, the epidemiology of injury, and global outcome determinants. These 25 questions were also reviewed with consideration given to the most likely source of federal funding of investigations. This report identifies the areas of trauma care in which research efforts might best be directed. Fully 40% of the key research questions could be considered to fall under the interest and auspices of the CDC-NCIPC. The remaining questions cover a broad range of topics and likely funding sources, emphasizing the need for a coordinated oversight of research funding in trauma care.
A new wave front shape-based approach for acoustic source localization in an anisotropic plate without knowing its material properties.

PubMed

Sen, Novonil; Kundu, Tribikram

2018-07-01

Estimating the location of an acoustic source in a structure is an important step towards passive structural health monitoring. Techniques for localizing an acoustic source in isotropic structures are well developed in the literature. Development of similar techniques for anisotropic structures, however, has gained attention only in the recent years and has a scope of further improvement. Most of the existing techniques for anisotropic structures either assume a straight line wave propagation path between the source and an ultrasonic sensor or require the material properties to be known. This study considers different shapes of the wave front generated during an acoustic event and develops a methodology to localize the acoustic source in an anisotropic plate from those wave front shapes. An elliptical wave front shape-based technique was developed first, followed by the development of a parametric curve-based technique for non-elliptical wave front shapes. The source coordinates are obtained by minimizing an objective function. The proposed methodology does not assume a straight line wave propagation path and can predict the source location without any knowledge of the elastic properties of the material. A numerical study presented here illustrates how the proposed methodology can accurately estimate the source coordinates. Copyright © 2018 Elsevier B.V. All rights reserved.
Minimization of nanosatellite low frequency magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belyayev, S. M., E-mail: belyayev@isr.lviv.ua; Royal Institute of Technology, Stockholm 11428; Dudkin, F. L.

2016-03-15

Small weight and dimensions of the micro- and nanosatellites constrain researchers to place electromagnetic sensors on short booms or on the satellite body. Therefore the electromagnetic cleanliness of such satellites becomes a central question. This paper describes the theoretical base and practical techniques for determining the parameters of DC and very low frequency magnetic interference sources. One of such sources is satellite magnetization, the reduction of which improves the accuracy and stability of the attitude control system. We present design solutions for magnetically clean spacecraft, testing equipment, and technology for magnetic moment measurements, which are more convenient, efficient, and accuratemore » than the conventional ones.« less
A compact 500 MHz 4 kW Solid-State Power Amplifier for accelerator applications

NASA Astrophysics Data System (ADS)

Gaspar, M.; Pedrozzi, M.; Ferreira, L. F. R.; Garvey, T.

2011-05-01

We present the development of a compact narrow-band Solid-State Power Amplifier (SSPA). We foresee a promising application of solid-state amplifiers specifically in accelerators for new generation synchrotron light sources. Such a new technology has reached a competitive price/performance ratio and expected lifetime in comparison with klystron and IOT amplifiers. The increasing number of synchrotron light sources using 500 MHz as base frequency justifies the effort in the development of the proposed amplifier. Two different techniques are also proposed to improve the control and performance of these new distributed amplification systems which we call, respectively, complete distributed system and forced compression.
Applications of absorption spectroscopy using quantum cascade lasers.

PubMed

Zhang, Lizhu; Tian, Guang; Li, Jingsong; Yu, Benli

2014-01-01

Infrared laser absorption spectroscopy (LAS) is a promising modern technique for sensing trace gases with high sensitivity, selectivity, and high time resolution. Mid-infrared quantum cascade lasers, operating in a pulsed or continuous wave mode, have potential as spectroscopic sources because of their narrow linewidths, single mode operation, tunability, high output power, reliability, low power consumption, and compactness. This paper reviews some important developments in modern laser absorption spectroscopy based on the use of quantum cascade laser (QCL) sources. Among the various laser spectroscopic methods, this review is focused on selected absorption spectroscopy applications of QCLs, with particular emphasis on molecular spectroscopy, industrial process control, combustion diagnostics, and medical breath analysis.
Observations of flat-spectrum radio sources at λ850 μm from the James Clerk Maxwell Telescope - I. 1997 April to 2000 April

NASA Astrophysics Data System (ADS)

Robson, E. I.; Stevens, J. A.; Jenness, T.

2001-11-01

Calibrated data for 65 flat-spectrum extragalactic radio sources are presented at a wavelength of 850μm, covering a three-year period from 1997 April. The data, obtained from the James Clerk Maxwell Telescope using the SCUBA camera in pointing mode, were analysed using an automated pipeline process based on the Observatory Reduction and Acquisition Control-Data Reduction (orac-dr) system. This paper describes the techniques used to analyse and calibrate the data, and presents the data base of results along with a representative sample of the better-sampled light curves.
Auditory spatial representations of the world are compressed in blind humans.

PubMed

Kolarik, Andrew J; Pardhan, Shahina; Cirstea, Silvia; Moore, Brian C J

2017-02-01

Compared to sighted listeners, blind listeners often display enhanced auditory spatial abilities such as localization in azimuth. However, less is known about whether blind humans can accurately judge distance in extrapersonal space using auditory cues alone. Using virtualization techniques, we show that auditory spatial representations of the world beyond the peripersonal space of blind listeners are compressed compared to those for normally sighted controls. Blind participants overestimated the distance to nearby sources and underestimated the distance to remote sound sources, in both reverberant and anechoic environments, and for speech, music, and noise signals. Functions relating judged and actual virtual distance were well fitted by compressive power functions, indicating that the absence of visual information regarding the distance of sound sources may prevent accurate calibration of the distance information provided by auditory signals.

Light curves of flat-spectrum radio sources (Jenness+, 2010)

NASA Astrophysics Data System (ADS)

Jenness, T.; Robson, E. I.; Stevens, J. A.

2010-05-01

Calibrated data for 143 flat-spectrum extragalactic radio sources are presented at a wavelength of 850um covering a 5-yr period from 2000 April. The data, obtained at the James Clerk Maxwell Telescope using the Submillimetre Common-User Bolometer Array (SCUBA) camera in pointing mode, were analysed using an automated pipeline process based on the Observatory Reduction and Acquisition Control - Data Reduction (ORAC-DR) system. This paper describes the techniques used to analyse and calibrate the data, and presents the data base of results along with a representative sample of the better-sampled light curves. A re-analysis of previously published data from 1997 to 2000 is also presented. The combined catalogue, comprising 10493 flux density measurements, provides a unique and valuable resource for studies of extragalactic radio sources. (2 data files).
Ion beam sputter modification of the surface morphology of biological implants

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Banks, B. A.

1976-01-01

The surface chemistry and texture of materials used for biological implants may significantly influence their performance and biocompatibility. Recent interest in the microscopic control of implant surface texture has led to the evaluation of ion beam sputtering as a potentially useful surface roughening technique. Ion sources, similar to electron bombardment ion thrusters designed for propulsive applications, are used to roughen the surfaces of various biocompatible alloys or polymer materials. These materials are typically used for dental implants, orthopedic prostheses, vascular prostheses, and artificial heart components. Masking techniques and resulting surface textures are described along with progress concerning evaluation of the biological response to the ion beam sputtered surfaces.
Ion-beam-sputter modification of the surface morphology of biological implants

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Banks, B. A.

1977-01-01

The surface chemistry and texture of materials used for biological implants may significantly influence their performance and biocompatibility. Recent interest in the microscopic control of implant surface texture has led to the evaluation of ion-beam sputtering as a potentially useful surface roughening technique. Ion sources, similar to electron-bombardment ion thrusters designed for propulsive applications, are used to roughen the surfaces of various biocompatible alloys or polymer materials. These materials are typically used for dental implants, orthopedic prostheses, vascular prostheses, and artificial heart components. Masking techniques and resulting surface textures are described along with progress concerning evaluation of the biological response to the ion-beam-sputtered surfaces.
Near-Field Magnetic Dipole Moment Analysis

NASA Technical Reports Server (NTRS)

Harris, Patrick K.

2003-01-01

This paper describes the data analysis technique used for magnetic testing at the NASA Goddard Space Flight Center (GSFC). Excellent results have been obtained using this technique to convert a spacecraft s measured magnetic field data into its respective magnetic dipole moment model. The model is most accurate with the earth s geomagnetic field cancelled in a spherical region bounded by the measurement magnetometers with a minimum radius large enough to enclose the magnetic source. Considerably enhanced spacecraft magnetic testing is offered by using this technique in conjunction with a computer-controlled magnetic field measurement system. Such a system, with real-time magnetic field display capabilities, has been incorporated into other existing magnetic measurement facilities and is also used at remote locations where transport to a magnetics test facility is impractical.
Apportionment of urban aerosol sources in Chongqing (China) using synergistic on-line techniques

NASA Astrophysics Data System (ADS)

Chen, Yang; Yang, Fumo

2016-04-01

The sources of ambient fine particulate matter (PM2.5) during wintertime at a background urban location in Chongqing (southwestern China) have been determined. Aerosol chemical composition analyses were performed using multiple on-line techniques, such as single particle aerosol mass spectrometer (SPAMS) for single particle chemical composition, on-line elemental carbon-organic carbon analyzer (on-line OC-EC), on-line X-ray fluorescence (XRF) for elements, and in-situ Gas and Aerosol Compositions monitor (IGAC) for water-soluble ions in PM2.5. All the datasets from these techniques have been adjusted to a 1-h time resolution for receptor model input. Positive matrix factorization (PMF) has been used for resolving aerosol sources. At least six sources, including domestic coal burning, biomass burning, dust, traffic, industrial and secondary/aged factors have been resolved and interpreted. The synergistic on-line techniques were helpful for identifying aerosol sources more clearly than when only employing the results from the individual techniques. This results are useful for better understanding of aerosol sources and atmospheric processes.
Control of submersible vortex flows

NASA Technical Reports Server (NTRS)

Bushnell, D. M.; Donaldson, C. D.

1990-01-01

Vortex flows produced by submersibles typically unfavorably influence key figures of merit such as acoustic and nonacoustic stealth, control effectiveness/maneuverability, and propulsor efficiency/body drag. Sources of such organized, primarily longitudinal, vorticity include the basic body (nose and sides) and appendages (both base/intersection and tip regions) such as the fairwater, dive planes, rear control surfaces, and propulsor stators/tips. Two fundamentally different vortex control approaches are available: (1) deintensification of the amplitude and/or organization of the vortex during its initiation process; and (2) downstream vortex disablement. Vortex control techniques applicable to the initiation region (deintensification approach) include transverse pressure gradient minimization via altered body cross section, appendage dillets, fillets, and sweep, and various appendage tip and spanload treatment along with the use of active controls to minimize control surface size and motions. Vortex disablement can be accomplished either via use of control vortices (which can also be used to steer the vortices off-board), direct unwinding, inducement of vortex bursting, or segmentation/tailoring for enhanced dissipation. Submersible-applicable vortex control technology is also included derived from various aeronautical applications such as mitigation of the wing wake vortex hazard and flight aircraft maneuverability at high angle of attack as well as the status of vortex effects upon, and mitigation of, nonlinear control forces on submersibles. Specific suggestions for submersible-applicable vortex control techniques are presented.
Utility of antioxidants during assisted reproductive techniques: an evidence based review.

PubMed

Agarwal, Ashok; Durairajanayagam, Damayanthi; du Plessis, Stefan S

2014-11-24

Assisted reproductive technology (ART) is a common treatment of choice for many couples facing infertility issues, be it due to male or female factor, or idiopathic. Employment of ART techniques, however, come with its own challenges as the in vitro environment is not nearly as ideal as the in vivo environment, where reactive oxygen species (ROS) build-up leading to oxidative stress is kept in check by the endogenous antioxidants system. While physiological amounts of ROS are necessary for normal reproductive function in vivo, in vitro manipulation of gametes and embryos exposes these cells to excessive ROS production either by endogenous or exogenous environmental factors. In this review, we discuss the sources of ROS in an in vitro clinical setting and the influence of oxidative stress on gamete/embryo quality and the outcome of IVF/ICSI. Sources of ROS and different strategies of overcoming the excessive generation of ROS in vitro are also highlighted. Endogenously, the gametes and the developing embryo become sources of ROS. Multiple exogenous factors act as potential sources of ROS, including exposure to visible light, composition of culture media, pH and temperature, oxygen concentration, centrifugation during spermatozoa preparation, ART technique involving handling of gamete/embryo and cryopreservation technique (freeze/thawing process). Finally, the use of antioxidants as agents to minimize ROS generation in the in vitro environment and as oral therapy is highlighted. Both enzymatic and non-enzymatic antioxidants are discussed and the outcome of studies using these antioxidants as oral therapy in the male or female or its use in vitro in media is presented. While results of studies using certain antioxidant agents are promising, the current body of evidence as a whole suggests the need for further well-designed and larger scale randomized controlled studies, as well as research to minimize oxidative stress conditions in the clinical ART setting.
Portable microcontroller-based instrument for near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Giardini, Mario E.; Corti, Mario; Lago, Paolo; Gelmetti, Andrea

2000-05-01

Near IR Spectroscopy (NIRS) can be employed to noninvasively and continuously measure in-vivo local changes in haemodynamics and oxygenation of human tissues. In particular, the technique can be particularly useful for muscular functional monitoring. We present a portable NIRS research-grade acquisition system prototype, strictly dedicate to low-noise measurements during muscular exercise. The prototype is able to control four LED sources and a detector. Such a number of sources allows for multipoint measurements or for multi-wavelength spectroscopy of tissue constituents other than oxygen, such as cytochrome aa3 oxidation. The LEDs and the detector are mounted on separate probes, which carry also the relevant drivers and preamplifiers. By employing surface-mount technologies, probe size and weight are kept to a minimum. A single-chip mixed-signal RISC microcontroller performs source-to- detector multiplexing with a digital correlation technique. The acquired data are stored on an on-board 64 K EEPROM bank, and can be subsequently uploaded to a personal computer via serial port for further analysis. The resulting instrument is compact and lightweight. Preliminary test of the prototype on oxygen consumption during tourniquet- induced forearm ischaemia show adequate detectivity and time response.
Improved performance of inkjet-printed Ag source/drain electrodes for organic thin-film transistors by overcoming the coffee ring effects

NASA Astrophysics Data System (ADS)

Liu, Cheng-Fang; Lin, Yan; Lai, Wen-Yong; Huang, Wei

2017-11-01

Inkjet printing is a promising technology for the scalable fabrication of organic electronics because of the material conservation and facile patterning as compared with other solution processing techniques. In this study, we have systematically investigated the cross-sectional profile control of silver (Ag) electrode via inkjet printing. A facile methodology for achieving inkjet-printed Ag source/drain with improved profiles is developed. It is demonstrated that the printing conditions such as substrate temperature, drop spacing and printing layers affect the magnitude of the droplet deposition and the rate of evaporation, which can be optimized to greatly reduce the coffee ring effects for improving the inkjet-printed electrode profiles. Ag source/drain electrodes with uniform profiles were successfully inkjet-printed and incorporated into organic thin-film transistors (OTFTs). The resulting devices showed superior electrical performance than those without special treatments. It is noted to mention that the strategy for modulating the inkjet-printed Ag electrodes in this work does not demand the ink formulation or complicated steps, which is beneficial for scaling up the printing techniques for potential large-area/mass manufacturing.
An optimal merging technique for high-resolution precipitation products: OPTIMAL MERGING OF PRECIPITATION METHOD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrestha, Roshan; Houser, Paul R.; Anantharaj, Valentine G.

2011-04-01

Precipitation products are currently available from various sources at higher spatial and temporal resolution than any time in the past. Each of the precipitation products has its strengths and weaknesses in availability, accuracy, resolution, retrieval techniques and quality control. By merging the precipitation data obtained from multiple sources, one can improve its information content by minimizing these issues. However, precipitation data merging poses challenges of scale-mismatch, and accurate error and bias assessment. In this paper we present Optimal Merging of Precipitation (OMP), a new method to merge precipitation data from multiple sources that are of different spatial and temporal resolutionsmore » and accuracies. This method is a combination of scale conversion and merging weight optimization, involving performance-tracing based on Bayesian statistics and trend-analysis, which yields merging weights for each precipitation data source. The weights are optimized at multiple scales to facilitate multiscale merging and better precipitation downscaling. Precipitation data used in the experiment include products from the 12-km resolution North American Land Data Assimilation (NLDAS) system, the 8-km resolution CMORPH and the 4-km resolution National Stage-IV QPE. The test cases demonstrate that the OMP method is capable of identifying a better data source and allocating a higher priority for them in the merging procedure, dynamically over the region and time period. This method is also effective in filtering out poor quality data introduced into the merging process.« less
Design methodology for micro-discrete planar optics with minimum illumination loss for an extended source.

PubMed

Shim, Jongmyeong; Park, Changsu; Lee, Jinhyung; Kang, Shinill

2016-08-08

Recently, studies have examined techniques for modeling the light distribution of light-emitting diodes (LEDs) for various applications owing to their low power consumption, longevity, and light weight. The energy mapping technique, a design method that matches the energy distributions of an LED light source and target area, has been the focus of active research because of its design efficiency and accuracy. However, these studies have not considered the effects of the emitting area of the LED source. Therefore, there are limitations to the design accuracy for small, high-power applications with a short distance between the light source and optical system. A design method for compensating for the light distribution of an extended source after the initial optics design based on a point source was proposed to overcome such limits, but its time-consuming process and limited design accuracy with multiple iterations raised the need for a new design method that considers an extended source in the initial design stage. This study proposed a method for designing discrete planar optics that controls the light distribution and minimizes the optical loss with an extended source and verified the proposed method experimentally. First, the extended source was modeled theoretically, and a design method for discrete planar optics with the optimum groove angle through energy mapping was proposed. To verify the design method, design for the discrete planar optics was achieved for applications in illumination for LED flash. In addition, discrete planar optics for LED illuminance were designed and fabricated to create a uniform illuminance distribution. Optical characterization of these structures showed that the design was optimal; i.e., we plotted the optical losses as a function of the groove angle, and found a clear minimum. Simulations and measurements showed that an efficient optical design was achieved for an extended source.
Air pollution source identification

NASA Technical Reports Server (NTRS)

Fordyce, J. S.

1975-01-01

Techniques for air pollution source identification are reviewed, and some results obtained with them are evaluated. Described techniques include remote sensing from satellites and aircraft, on-site monitoring, and the use of injected tracers and pollutants themselves as tracers. The use of a large number of trace elements in ambient airborne particulate matter as a practical means of identifying sources is discussed in detail. Sampling and analysis techniques are described, and it is shown that elemental constituents can be related to specific source types such as those found in the earth's crust and those associated with specific industries. Source identification sytems are noted which utilize charged particle X-ray fluorescence analysis of original field data.
Active noise attenuation in ventilation windows.

PubMed

Huang, Huahua; Qiu, Xiaojun; Kang, Jian

2011-07-01

The feasibility of applying active noise control techniques to attenuate low frequency noise transmission through a natural ventilation window into a room is investigated analytically and experimentally. The window system is constructed by staggering the opening sashes of a spaced double glazing window to allow ventilation and natural light. An analytical model based on the modal expansion method is developed to calculate the low frequency sound field inside the window and the room and to be used in the active noise control simulations. The effectiveness of the proposed analytical model is validated by using the finite element method. The performance of the active control system for a window with different source and receiver configurations are compared, and it is found that the numerical and experimental results are in good agreement and the best result is achieved when the secondary sources are placed in the center at the bottom of the staggered window. The extra attenuation at the observation points in the optimized window system is almost equivalent to the noise reduction at the error sensor and the frequency range of effective control is up to 390 Hz in the case of a single channel active noise control system. © 2011 Acoustical Society of America
An investigation of the source of air Ar contamination in KAr dating

USGS Publications Warehouse

Mussett, A.E.; Brent, Dalrymple G.

1968-01-01

Precision of young KAr ages is limited by air argon contamination. A series of experiments in which the exposure of basalt and sanidine samples to air argon was controlled, shows that most of the air contamination does not arise in the laboratory. Because of this, it seems unlikely that air argon contamination can be significantly reduced by special sample handling and preparation techniques. ?? 1968.
A Compilation of Common Algal Control and Management Techniques.

DTIC Science & Technology

1980-01-01

sources within their exten- sive watersheds. Excessive algal production and the subsequent decay of algal biomass often result in oxygen depletion...organisms in the food chain. c. Harmless to man and animals. 8 d. No incorporation into mineral or biological cycles. e. No adverse effect on water...phytoplankton decreased by ca 30 percent and, due to better light conditions, the productive layer increased. The number of zooplankton, especially
A System Approach to Navy Medical Education and Training. Appendix 2. Task Inventory Booklet (Form N21-Physicians).

DTIC Science & Technology

1974-08-31

STOREC PROPERLY 37 ICHECK INSTRUMENTS ANn SUPPLIES FOR STERILIZATION INDICATORS 38 IDETERMINE ADEQUACY OF STERILIZATION PROCEDURES 39 IINSPECT SUPPLIES...NARCOTICS/CONTROLLED DRUGS/ALCOHCL TO WARO/CLINIC/OTHER IDEPARTMENTS 5 ISEARCH FOR UNACCOUNTABLE WARD/CLINIC NARCOTICSICONTPOLLED DRUGS 6 ICHECK ...SOURCES OF BACTERIAL CONTAMINATICN 30 IREVIEW -ND EVALUATE ASEPTIC TECHNIQUES 31 IINSPECT SPACES FOR INSECT INFESTATION 32 ICHECK EQUIPMENT FCR
Summary report of working group 5: Beam sources, monitoring and control

NASA Astrophysics Data System (ADS)

Conde, Manoel; Zgadzaj, Rafal

2017-03-01

This paper summarizes the topics presented in Working Group 5 at the 17th Advanced Accelerator Concepts Workshop, which was held from 31 July to 5 August 2016 at the Gaylord Hotel and Conference Center, National Harbor, MD, USA. The presentations included a variety of topics covering cathode and RF gun design, new user facilities, beam phase space manipulation, and a range of novel diagnostic techniques.
Comparison of Logistic Regression and Random Forests techniques for shallow landslide susceptibility assessment in Giampilieri (NE Sicily, Italy)

NASA Astrophysics Data System (ADS)

Trigila, Alessandro; Iadanza, Carla; Esposito, Carlo; Scarascia-Mugnozza, Gabriele

2015-11-01

The aim of this work is to define reliable susceptibility models for shallow landslides using Logistic Regression and Random Forests multivariate statistical techniques. The study area, located in North-East Sicily, was hit on October 1st 2009 by a severe rainstorm (225 mm of cumulative rainfall in 7 h) which caused flash floods and more than 1000 landslides. Several small villages, such as Giampilieri, were hit with 31 fatalities, 6 missing persons and damage to buildings and transportation infrastructures. Landslides, mainly types such as earth and debris translational slides evolving into debris flows, were triggered on steep slopes and involved colluvium and regolith materials which cover the underlying metamorphic bedrock. The work has been carried out with the following steps: i) realization of a detailed event landslide inventory map through field surveys coupled with observation of high resolution aerial colour orthophoto; ii) identification of landslide source areas; iii) data preparation of landslide controlling factors and descriptive statistics based on a bivariate method (Frequency Ratio) to get an initial overview on existing relationships between causative factors and shallow landslide source areas; iv) choice of criteria for the selection and sizing of the mapping unit; v) implementation of 5 multivariate statistical susceptibility models based on Logistic Regression and Random Forests techniques and focused on landslide source areas; vi) evaluation of the influence of sample size and type of sampling on results and performance of the models; vii) evaluation of the predictive capabilities of the models using ROC curve, AUC and contingency tables; viii) comparison of model results and obtained susceptibility maps; and ix) analysis of temporal variation of landslide susceptibility related to input parameter changes. Models based on Logistic Regression and Random Forests have demonstrated excellent predictive capabilities. Land use and wildfire variables were found to have a strong control on the occurrence of very rapid shallow landslides.
Evaluation of Nonpoint-Source Contamination, Wisconsin: Selected Topics for Water Year 1995

USGS Publications Warehouse

Owens, D.W.; Corsi, Steven R.; Rappold, K.F.

1997-01-01

The objective of the watershed-management evaluation monitoring program in Wisconsin is to evaluate the effectiveness of best-management practices (BMP's) for controlling nonpoint-source contamination in eight rural and four urban watersheds. This report, the fourth in an annual series of reports, presents a summary of the data collected for the program by the U.S. Geological Survey and the results of several detailed analyses of the data. To complement assessments of water quality, a land-use and BMP inventory is ongoing for 12 evaluation monitoring projects to track nonpoint sources of contamination in each watershed and to document implementation of BMP's that were designed to cause changes in the water quality of streams. Each year, updated information is gathered, mapped, and stored in a geographic-information-system data base. Summaries of land-use, BMP implementation, and water-quality data collected during water years 1989-95 are presented. Storm loads, snowmelt-period loads, and annual loads of suspended sediment and total phosphorus are summarized for eight rural sites. Storm-load data for suspended solids, total phosphorus, total recoverable lead, copper, zinc, and cadmium are summarized for four urban sites. Quality-assurance and quality-control (QA/QC) samples were collected at the eight rural sites to evaluate inorganic sample contamination and at one urban site to evaluate sample-collection and filtration techniques for polycyclic aromatic hydrocarbons (PAR's). Some suspended solids and fecal coliform contamination was detected at the rural sites. Corrective actions will be taken to address this contamination. Evaluation of PAR sample-collection techniques did not uncover any deficiencies, but the small amount of data collected was not sufficient to draw any definite conclusions. Evaluation of PAR filtration techniques indicate that water-sample filtration with O.7-um glass-fiber filters in an aluminum filter unit does not result in significant loss of PAR.
Medical Expenditures among Immigrant and Non-Immigrant Groups in the U.S.: Findings from the Medical Expenditures Panel Survey (2000–2008)

PubMed Central

Tarraf, Wassim; Miranda, Patricia Y.; González, Hector M.

2011-01-01

Objective To examine time trends and differences in medical expenditures between non-citizens, foreign-born, and U.S.-born citizens. Methods We used multi-year Medical Expenditures Panel Survey (2000–2008) data on non-institutionalized adults in the U.S. (N=190,965). Source specific and total medical expenditures were analyzed using regression models, bootstrap prediction techniques, and linear and non-linear decomposition methods to evaluate the relationship between immigration status and expenditures, controlling for confounding effects. Results We found that the average health expenditures between 2000 and 2008 for non-citizens immigrants ($1,836) were substantially lower compared to both foreign-born ($3,737) and U.S.-born citizens ($4,478). Differences were maintained after controlling for confounding effects. Decomposition techniques showed that the main determinants of these differences were the availability of a usual source of healthcare, insurance, and ethnicity/race. Conclusion Lower healthcare expenditures among immigrants result from disparate access to healthcare. The dissipation of demographic advantages among immigrants could prospectively produce higher pressures on the U.S. healthcare system as immigrants age and levels of chronic conditions rise. Barring a shift in policy, the brunt of the effects could be borne by an already overextended public healthcare system. PMID:22222383

Techniques for grid manipulation and adaptation. [computational fluid dynamics

NASA Technical Reports Server (NTRS)

Choo, Yung K.; Eisemann, Peter R.; Lee, Ki D.

1992-01-01

Two approaches have been taken to provide systematic grid manipulation for improved grid quality. One is the control point form (CPF) of algebraic grid generation. It provides explicit control of the physical grid shape and grid spacing through the movement of the control points. It works well in the interactive computer graphics environment and hence can be a good candidate for integration with other emerging technologies. The other approach is grid adaptation using a numerical mapping between the physical space and a parametric space. Grid adaptation is achieved by modifying the mapping functions through the effects of grid control sources. The adaptation process can be repeated in a cyclic manner if satisfactory results are not achieved after a single application.
Functions of the human frontoparietal attention network: Evidence from neuroimaging

PubMed Central

Scolari, Miranda; Seidl-Rathkopf, Katharina N; Kastner, Sabine

2016-01-01

Human frontoparietal cortex has long been implicated as a source of attentional control. However, the mechanistic underpinnings of these control functions have remained elusive due to limitations of neuroimaging techniques that rely on anatomical landmarks to localize patterns of activation. The recent advent of topographic mapping via functional magnetic resonance imaging (fMRI) has allowed the reliable parcellation of the network into 18 independent subregions in individual subjects, thereby offering unprecedented opportunities to address a wide range of empirical questions as to how mechanisms of control operate. Here, we review the human neuroimaging literature that has begun to explore space-based, feature-based, object-based and category-based attentional control within the context of topographically defined frontoparietal cortex. PMID:27398396
Passive lighting responsive three-dimensional integral imaging

NASA Astrophysics Data System (ADS)

Lou, Yimin; Hu, Juanmei

2017-11-01

A three dimensional (3D) integral imaging (II) technique with a real-time passive lighting responsive ability and vivid 3D performance has been proposed and demonstrated. Some novel lighting responsive phenomena, including light-activated 3D imaging, and light-controlled 3D image scaling and translation, have been realized optically without updating images. By switching the on/off state of a point light source illuminated on the proposed II system, the 3D images can show/hide independent of the diffused illumination background. By changing the position or illumination direction of the point light source, the position and magnification of the 3D image can be modulated in real time. The lighting responsive mechanism of the 3D II system is deduced analytically and verified experimentally. A flexible thin film lighting responsive II system with a 0.4 mm thickness was fabricated. This technique gives some additional degrees of freedom in order to design the II system and enable the virtual 3D image to interact with the real illumination environment in real time.
Magneto-hydrodynamically stable axisymmetric mirrorsa)

NASA Astrophysics Data System (ADS)

Ryutov, D. D.; Berk, H. L.; Cohen, B. I.; Molvik, A. W.; Simonen, T. C.

2011-09-01

Making axisymmetric mirrors magnetohydrodynamically (MHD) stable opens up exciting opportunities for using mirror devices as neutron sources, fusion-fission hybrids, and pure-fusion reactors. This is also of interest from a general physics standpoint (as it seemingly contradicts well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole mirror configurations. In this tutorial, after a summary of classical results, several techniques for achieving MHD stabilization of the axisymmetric mirrors are considered, in particular: (1) employing the favorable field-line curvature in the end tanks; (2) using the line-tying effect; (3) controlling the radial potential distribution; (4) imposing a divertor configuration on the solenoidal magnetic field; and (5) affecting the plasma dynamics by the ponderomotive force. Some illuminative theoretical approaches for understanding axisymmetric mirror stability are described. The applicability of the various stabilization techniques to axisymmetric mirrors as neutron sources, hybrids, and pure-fusion reactors are discussed; and the constraints on the plasma parameters are formulated.
Automated strip-mine and reclamation mapping from ERTS

NASA Technical Reports Server (NTRS)

Rogers, R. H. (Principal Investigator); Reed, L. E.; Pettyjohn, W. A.

1974-01-01

The author has identified the following significant results. Computer processing techniques were applied to ERTS-1 computer-compatible tape (CCT) data acquired in August 1972 on the Ohio Power Company's coal mining operation in Muskingum County, Ohio. Processing results succeeded in automatically classifying, with an accuracy greater than 90%: (1) stripped earth and major sources of erosion; (2) partially reclaimed areas and minor sources of erosion; (3) water with sedimentation; (4) water without sedimentation; and (5) vegetation. Computer-generated tables listing the area in acres and square kilometers were produced for each target category. Processing results also included geometrically corrected map overlays, one for each target category, drawn on a transparent material by a pen under computer control. Each target category is assigned a distinctive color on the overlay to facilitate interpretation. The overlays, drawn at a scale of 1:250,000 when placed over an AMS map of the same area, immediately provided map locations for each target. These mapping products were generated at a tenth of the cost of conventional mapping techniques.
Preponderance of toxigenic Escherichia coli in stool pathogens correlates with toxin detection in accessible drinking-water sources.

PubMed

Igbokwe, H; Bhattacharyya, S; Gradus, S; Khubbar, M; Griswold, D; Navidad, J; Igwilo, C; Masson-Meyers, D; Azenabor, A A

2015-02-01

Since early detection of pathogens and their virulence factors contribute to intervention and control strategies, we assessed the enteropathogens in diarrhoea disease and investigated the link between toxigenic strains of Escherichia coli from stool and drinking-water sources; and determined the expression of toxin genes by antibiotic-resistant E. coli in Lagos, Nigeria. This was compared with isolates from diarrhoeal stool and water from Wisconsin, USA. The new Luminex xTAG GPP (Gastroplex) technique and conventional real-time PCR were used to profile enteric pathogens and E. coli toxin gene isolates, respectively. Results showed the pathogen profile of stool and indicated a relationship between E. coli toxin genes in water and stool from Lagos which was absent in Wisconsin isolates. The Gastroplex technique was efficient for multiple enteric pathogens and toxin gene detection. The co-existence of antibiotic resistance with enteroinvasive E. coli toxin genes suggests an additional prognostic burden on patients.
A novel sensor for two-degree-of-freedom motion measurement of linear nanopositioning stage using knife edge displacement sensing technique

NASA Astrophysics Data System (ADS)

Zolfaghari, Abolfazl; Jeon, Seongkyul; Stepanick, Christopher K.; Lee, ChaBum

2017-06-01

This paper presents a novel method for measuring two-degree-of-freedom (DOF) motion of flexure-based nanopositioning systems based on optical knife-edge sensing (OKES) technology, which utilizes the interference of two superimposed waves: a geometrical wave from the primary source of light and a boundary diffraction wave from the secondary source. This technique allows for two-DOF motion measurement of the linear and pitch motions of nanopositioning systems. Two capacitive sensors (CSs) are used for a baseline comparison with the proposed sensor by simultaneously measuring the motions of the nanopositioning system. The experimental results show that the proposed sensor closely agrees with the fundamental linear motion of the CS. However, the two-DOF OKES technology was shown to be approximately three times more sensitive to the pitch motion than the CS. The discrepancy in the two sensor outputs is discussed in terms of measuring principle, linearity, bandwidth, control effectiveness, and resolution.
On the path to fusion energy

NASA Astrophysics Data System (ADS)

Tabak, M.

2016-10-01

There is a need to develop alternate energy sources in the coming century because fossil fuels will become depleted and their use may lead to global climate change. Inertial fusion can become such an energy source, but significant progress must be made before its promise is realized. The high-density approach to inertial fusion suggested by Nuckolls et al. leads reaction chambers compatible with civilian power production. Methods to achieve the good control of hydrodynamic stability and implosion symmetry required to achieve these high fuel densities will be discussed. Fast Ignition, a technique that achieves fusion ignition by igniting fusion fuel after it is assembled, will be described along with its gain curves. Fusion costs of energy for conventional hotspot ignition will be compared with those of Fast Ignition and their capital costs compared with advanced fission plants. Finally, techniques that may improve possible Fast Ignition gains by an order of magnitude and reduce driver scales by an order of magnitude below conventional ignition requirements are described.
Reducing Brain Signal Noise in the Prediction of Economic Choices: A Case Study in Neuroeconomics

PubMed Central

Sundararajan, Raanju R.; Palma, Marco A.; Pourahmadi, Mohsen

2017-01-01

In order to reduce the noise of brain signals, neuroeconomic experiments typically aggregate data from hundreds of trials collected from a few individuals. This contrasts with the principle of simple and controlled designs in experimental and behavioral economics. We use a frequency domain variant of the stationary subspace analysis (SSA) technique, denoted as DSSA, to filter out the noise (nonstationary sources) in EEG brain signals. The nonstationary sources in the brain signal are associated with variations in the mental state that are unrelated to the experimental task. DSSA is a powerful tool for reducing the number of trials needed from each participant in neuroeconomic experiments and also for improving the prediction performance of an economic choice task. For a single trial, when DSSA is used as a noise reduction technique, the prediction model in a food snack choice experiment has an increase in overall accuracy by around 10% and in sensitivity and specificity by around 20% and in AUC by around 30%, respectively. PMID:29311784
Reducing Brain Signal Noise in the Prediction of Economic Choices: A Case Study in Neuroeconomics.

PubMed

Sundararajan, Raanju R; Palma, Marco A; Pourahmadi, Mohsen

2017-01-01

In order to reduce the noise of brain signals, neuroeconomic experiments typically aggregate data from hundreds of trials collected from a few individuals. This contrasts with the principle of simple and controlled designs in experimental and behavioral economics. We use a frequency domain variant of the stationary subspace analysis (SSA) technique, denoted as DSSA, to filter out the noise (nonstationary sources) in EEG brain signals. The nonstationary sources in the brain signal are associated with variations in the mental state that are unrelated to the experimental task. DSSA is a powerful tool for reducing the number of trials needed from each participant in neuroeconomic experiments and also for improving the prediction performance of an economic choice task. For a single trial, when DSSA is used as a noise reduction technique, the prediction model in a food snack choice experiment has an increase in overall accuracy by around 10% and in sensitivity and specificity by around 20% and in AUC by around 30%, respectively.
Resolving small signal measurements in experimental plasma environments using calibrated subtraction of noise signals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fimognari, P. J., E-mail: PJFimognari@XanthoTechnologies.com; Demers, D. R.; Chen, X.

2014-11-15

The performance of many diagnostic and control systems within fusion and other fields of research are often detrimentally affected by spurious noise signals. This is particularly true for those (such as radiation or particle detectors) working with very small signals. Common sources of radiated and conducted noise in experimental fusion environments include the plasma itself and instrumentation. The noise complicates data analysis, as illustrated by noise on signals measured with the heavy ion beam probe (HIBP) installed on the Madison Symmetric Torus. The noise is time-varying and often exceeds the secondary ion beam current (in contrast with previous applications). Analysismore » of the noise identifies the dominant source as photoelectric emission from the detectors induced by ultraviolet light from the plasma. This has led to the development of a calibrated subtraction technique, which largely removes the undesired temporal noise signals from data. The advantages of the technique for small signal measurement applications are demonstrated through improvements realized on HIBP fluctuation measurements.« less
Maximum power point tracking for photovoltaic applications by using two-level DC/DC boost converter

NASA Astrophysics Data System (ADS)

Moamaei, Parvin

Recently, photovoltaic (PV) generation is becoming increasingly popular in industrial applications. As a renewable and alternative source of energy they feature superior characteristics such as being clean and silent along with less maintenance problems compared to other sources of the energy. In PV generation, employing a Maximum Power Point Tracking (MPPT) method is essential to obtain the maximum available solar energy. Among several proposed MPPT techniques, the Perturbation and Observation (P&O;) and Model Predictive Control (MPC) methods are adopted in this work. The components of the MPPT control system which are P&O; and MPC algorithms, PV module and high gain DC-DC boost converter are simulated in MATLAB Simulink. They are evaluated theoretically under rapidly and slowly changing of solar irradiation and temperature and their performance is shown by the simulation results, finally a comprehensive comparison is presented.
Survey of instrumentation for environmental monitoring: major update. Volume 3. Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1979-09-01

This is the third volume of a four-volume (seven-part) series, the culmination of a comprehensive survey of instrumentation for environmental monitoring. Consideration is given to instruments and techniques presently in use and to those developed for other purposes but having possible applications to radiation monitoring. The results of the survey are given as descriptions of the physical and operating characteristics of available instruments, critical comparisons among instrumentation methods, and recommendations of promising methodology and development of new instrumentation. Information is also given regarding the pollutants to be monitored, their characteristics and forms, their sources and pathways, their effects on themore » ecosystem, and the means of controlling them through process and regulatory controls. The discussion is presented under sections entitled radiation sources; instrumentation: by type of radiation or instrument type; and, instrumentation for specific radionuclides. (JGB)« less
Fan noise research at NASA

NASA Technical Reports Server (NTRS)

Groeneweg, John F.

1994-01-01

Results of recent NASA research to reduce aircraft turbofan noise are described. As the bypass ratio of a turbofan engine increases from 5 to as much as 20, the dominant source of engine noise is the fan. A primary mechanism of tone noise generation is the rotor blade wakes interacting with downstream stator vanes. Methods of analyzing rotor-stator tone noise generation are described and sample results are given. The role of an acoustic modal description is emphasized. Wind tunnel tests of model fans and nacelles are described including a novel rotating microphone technique for modal measurement. Sample far field results are given showing the effects of inlet length, and modal measurements are shown which point to a new generation mechanism. Concepts for active fan noise control at the source are addressed. Implications of the research which have general relevance to fan noise generation and control are discussed.
Fan noise research at NASA

NASA Astrophysics Data System (ADS)

Groeneweg, John F.

Results of recent NASA research to reduce aircraft turbofan noise are described. As the bypass ratio of a turbofan engine increases from 5 to as much as 20, the dominant source of engine noise is the fan. A primary mechanism of tone noise generation is the rotor blade wakes interacting with downstream stator vanes. Methods of analyzing rotor-stator tone noise generation are described and sample results are given. The role of an acoustic modal description is emphasized. Wind tunnel tests of model fans and nacelles are described including a novel rotating microphone technique for modal measurement. Sample far field results are given showing the effects of inlet length, and modal measurements are shown which point to a new generation mechanism. Concepts for active fan noise control at the source are addressed. Implications of the research which have general relevance to fan noise generation and control are discussed.
Solid-state surface luminescence of polycyclic aromatic hydrocarbons adsorbed on cellulose diacetate matrices

NASA Astrophysics Data System (ADS)

Rogacheva, Svetlana M.; Shipovskaya, Anna B.; Volkova, Elena V.; Khurshudyan, Grachia N.; Suska-Malawska, Malgorzata; Gubina, Tamara I.

2018-04-01

The spectral-kinetic characteristics of luminescence of 17 polycyclic aromatic hydrocarbons (PAH) sorbed from a "water-organic solvent" medium on cellulose diacetate (CDA) matrices were studied. A significant increase in the fluorescence signal on the CDA matrix was observed for 13 PAHs in comparison with aqueous solutions. The highest detection sensitivity was found for pyrene, benzo(a)pyrene, and benzo(k)fluoranthene. The fluorescence spectra of two PAH indicator pairs (anthracene-phenanthrene and pyrene-fluoranthene) used to control toxicant emission sources were studied with the simultaneous presence of isomers in the analyte, depending on the excitation wavelength. For both isomer pairs, it has been found that the spectra of their solid-state luminescence overlap insignificantly, the characteristic peaks do not coincide and do not overlap, the sensitivities of detection are close to each other, which makes it possible to consider this technique as promising to control PAH contamination sources.
Widely tunable (PbSn)Te lasers using etched cavities for mass production. [for infrared spectroscopic applications

NASA Technical Reports Server (NTRS)

Miller, M. D.

1980-01-01

Lead salt diode lasers are being used increasingly as tunable sources of monochromatic infrared radiation in a variety of spectroscopic systems. These devices are particularly useful, both in the laboratory and in the field, because of their high spectral brightness (compared to thermal sources) and wide spectral coverage (compared to line-tunable gas lasers). While the primary commercial application of these lasers has been for ultrahigh resolution laboratory spectroscopy, there are numerous systems applications, including laser absorbtion pollution monitors and laser heterodyne radiometers, for which diode lasers have great potential utility. Problem areas related to the wider use of these components are identified. Among these are total tuning range, mode control, and high fabrication cost. A fabrication technique which specifically addresses the problems of tuning range and cost, and which also has potential application for mode control, is reported.
Evidence for expression of eosinophil-associated IL-12 messenger RNA and immunoreactivity in bronchial asthma.

PubMed

Nutku, E; Gounni, A S; Olivenstein, R; Hamid, Q

2000-08-01

Eosinophils are a source of cytokines within the airways of asthmatic individuals that may exert an important immunoregulatory influence. We examined IL-12 messenger (m)RNA and protein expression in eosinophils from peripheral blood and bronchoalveolar lavage (BAL) fluid obtained from subjects with atopic asthma (n = 7), patients with chronic bronchitis (n = 5), and nonatopic healthy control subjects (n = 7). To further define this IL-12(+) population of eosinophils for the expression of other cytokines, we colocalized IL-12 and IL-5 within the peripheral blood eosinophils. To detect IL-12 mRNA and protein expression, we used in situ hybridization and immunocytochemistry techniques. The double-immunocytochemistry technique was used to localize IL-12 protein to BAL eosinophils and to colocalize IL-5 and IL-12 in peripheral blood eosinophils. IL-12 mRNA and immunoreactive protein were localized to peripheral blood eosinophils. BAL fluid-derived eosinophils from asthmatic subjects were also reactive to IL-12. The percentage of peripheral blood eosinophils expressing mRNA for IL-12 was significantly lower in asthmatic subjects compared with that found in eosinophils obtained from patients with chronic bronchitis (P<.001) and control patients (P <.05). Colocalization studies demonstrated that the percentages of IL-12(+) eosinophils that are also IL-5(+) were 72% in asthmatic subjects and only 11% in control subjects (P<.001). These results suggest that eosinophils are a potential source of IL-12. Eosinophil-derived IL-12 may contribute and modulate the local allergic inflammatory responses.
Healing potential of transplanted allogeneic chondrocytes of three different sources in lesions of the avascular zone of the meniscus: a pilot study.

PubMed

Weinand, Christian; Peretti, Giuseppe M; Adams, Samuel B; Randolph, Mark A; Savvidis, Estafios; Gill, Thomas J

2006-11-01

Successful treatment of tears to the avascular region of the meniscus remains a challenge. Current repair techniques, such as sutures and anchors, are effective in stabilizing the peripheral, vascularized regions of the meniscus, but are not adequate for promoting healing in the avascular region. The purpose of this study was to demonstrate the healing ability of a tissue-engineered repair technique using allogenic chondrocytes from three different sources for the avascular zone of the meniscus. Articular, auricular, and costal chondrocytes were harvested from 3-month-old Yorkshire swine. A 1-cm bucket-handle lesion was created in the avascular zone of each three swine. A cell-scaffold construct, composed of a single chondrocyte cell type and Vicryl mesh, was implanted into the lesion and secured with two vertical mattress sutures. Controls consisted of each three sutured unseeded mesh implants, suture only, and untreated lesions. The swine were allowed immediate post-operative full weight bearing. Menisci and controls were harvested after 12 weeks. In all experimental samples, lesion closure was observed. Gross mechanical testing with two Adson forceps demonstrated bonding of the lesion. Histological analysis showed formation of new tissue in all three experimental samples. None of the control samples demonstrated closure and formation of new matrix. We present preliminary data that demonstrates the potential of a tissue-engineered, allogenic cellular repair to provide successful healing of lesions in the avascular zone in a large animal model.
Optical Sensors for Use in Propulsion Control Systems

NASA Technical Reports Server (NTRS)

Fritsch, Klaus

1997-01-01

This final technical report describes the results of a cooperative effort which was originally established between John Carroll University and the Instrumentation and Control Technology Division at NASA Lewis Research Center on November, 1982, and then continued with the Engine Sensor Technology Branch at NASA Lewis until March, 1995. All work at John Carroll University was directed by the principal investigator of this grant, Klaus Fritsch, Ph.D. For the first two years of this grant this effort was supervised at NASA by Mr. Robert J. Baumbick and for the remainder of the grant by Dr. Glenn M. Beheim. All research was carried out in close cooperation with Dr. Beheim. Electrically passive optical sensors for measurands such as pressure, temperature, position, and rotational speed are required for aircraft engine control in fly-by-light digital aircraft control systems. Fiberoptic data links and optical multiplexing techniques should be used for combining and processing the outputs from several sensors, sharing as many optical end electronic parts as possible. The overall objective of this grant was to explore techniques for designing and constructing such electrically passive optical sensors for measuring physical parameters in jet aircraft engines and for use in aircraft control systems. We have concentrated our efforts on pressure, temperature, and position sensors employing techniques which are relatively immune to transmissivity variations of the fiber links and to variations in intensity of the light source. Infrared light-emitting diodes are employed because of their longevity and immunity to vibration. We have also studied a number of multiplexing techniques. On the following pages I will give thumbnail sketches of the projects carried out under this grant and provide references to publications and John Carroll M.S. theses which resulted directly from this work and which describe these projects in greater detail.

Evaluating barnyard Best Management Practices in Wisconsin using upstream-downstream monitoring

USGS Publications Warehouse

Stuntebeck, Todd D.

1995-01-01

The Nonpoint Source Water Pollution Abatement Program was created in 1978 by the Wisconsin Legislature. The goal of the program is to improve and protect the water quality of lakes, streams, wetlands, and ground water within selected priority watersheds by controlling sources of nonpoint pollution. For each selected watershed, the Wisconsin Department of Natural Resources drafts a management plan that guides the implementation of pollution-control strategies known as Best Management Practices (BMP's). This plan summarizes resource and land-use inventories, describes the results of pollution-source modeling, and suggests pollution reduction goals. The U.S. Geological Survey, through a cooperative effort with the Wisconsin Department of Natural Resources, is monitoring water-quality improvements that result from the implementation of BMP's. The data collected are then compared to the watershed plans to assess progress and determine whether goals are being realized. This fact sheet describes the data-collection efforts, preliminary results, and planned data-analysis techniques of monitoring projects for pre-BMP conditions at two barnyards, one each on Otter Creek and Halfway Prairie Creek.
Physical and numerical sources of computational inefficiency in integration of chemical kinetic rate equations: Etiology, treatment and prognosis

NASA Technical Reports Server (NTRS)

Pratt, D. T.; Radhakrishnan, K.

1986-01-01

The design of a very fast, automatic black-box code for homogeneous, gas-phase chemical kinetics problems requires an understanding of the physical and numerical sources of computational inefficiency. Some major sources reviewed in this report are stiffness of the governing ordinary differential equations (ODE's) and its detection, choice of appropriate method (i.e., integration algorithm plus step-size control strategy), nonphysical initial conditions, and too frequent evaluation of thermochemical and kinetic properties. Specific techniques are recommended (and some advised against) for improving or overcoming the identified problem areas. It is argued that, because reactive species increase exponentially with time during induction, and all species exhibit asymptotic, exponential decay with time during equilibration, exponential-fitted integration algorithms are inherently more accurate for kinetics modeling than classical, polynomial-interpolant methods for the same computational work. But current codes using the exponential-fitted method lack the sophisticated stepsize-control logic of existing black-box ODE solver codes, such as EPISODE and LSODE. The ultimate chemical kinetics code does not exist yet, but the general characteristics of such a code are becoming apparent.
PCB remediation in schools: a review.

PubMed

Brown, Kathleen W; Minegishi, Taeko; Cummiskey, Cynthia Campisano; Fragala, Matt A; Hartman, Ross; MacIntosh, David L

2016-02-01

Growing awareness of polychlorinated biphenyls (PCBs) in legacy caulk and other construction materials of schools has created a need for information on best practices to control human exposures and comply with applicable regulations. A concise review of approaches and techniques for management of building-related PCBs is the focus of this paper. Engineering and administrative controls that block pathways of PCB transport, dilute concentrations of PCBs in indoor air or other exposure media, or establish uses of building space that mitigate exposure can be effective initial responses to identification of PCBs in a building. Mitigation measures also provide time for school officials to plan a longer-term remediation strategy and to secure the necessary resources. These longer-term strategies typically involve removal of caulk or other primary sources of PCBs as well as nearby masonry or other materials contaminated with PCBs by the primary sources. The costs of managing PCB-containing building materials from assessment through ultimate disposal can be substantial. Optimizing the efficacy and cost-effectiveness of remediation programs requires aligning a thorough understanding of sources and exposure pathways with the most appropriate mitigation and abatement methods.
Pelvic packing or angiography: competitive or complementary?

PubMed

Suzuki, Takashi; Smith, Wade R; Moore, Ernest E

2009-04-01

Pelvic angiography is an established technique that has evolved into a highly effective means of controlling arterial pelvic haemorrhage. The current dominant paradigm for haemodynamically unstable patients with pelvic fractures is angiographic management combined with mechanical stabilisation of the pelvis. However, an effective rapid screening tool for arterial bleeding in pelvic fracture patients has yet to be identified. There is also no precise way to determine the major source of bleeding responsible for haemodynamic instability. In many pelvic fracture patients, bleeding is from venous lacerations which are not effectively treated with angiography to fractured bony surfaces. Modern pelvic packing consists of time-saving and minimally invasive techniques which appear to result in effective control of the haemorrhage via tamponade. This review article focuses on the recent body of knowledge on angiography and pelvic packing. We propose the optimal role for each modality in trauma centres.
Classification of smoke tainted wines using mid-infrared spectroscopy and chemometrics.

PubMed

Fudge, Anthea L; Wilkinson, Kerry L; Ristic, Renata; Cozzolino, Daniel

2012-01-11

In this study, the suitability of mid-infrared (MIR) spectroscopy, combined with principal component analysis (PCA) and linear discriminant analysis (LDA), was evaluated as a rapid analytical technique to identify smoke tainted wines. Control (i.e., unsmoked) and smoke-affected wines (260 in total) from experimental and commercial sources were analyzed by MIR spectroscopy and chemometrics. The concentrations of guaiacol and 4-methylguaiacol were also determined using gas chromatography-mass spectrometry (GC-MS), as markers of smoke taint. LDA models correctly classified 61% of control wines and 70% of smoke-affected wines. Classification rates were found to be influenced by the extent of smoke taint (based on GC-MS and informal sensory assessment), as well as qualitative differences in wine composition due to grape variety and oak maturation. Overall, the potential application of MIR spectroscopy combined with chemometrics as a rapid analytical technique for screening smoke-affected wines was demonstrated.
Synchronization trigger control system for flow visualization

NASA Technical Reports Server (NTRS)

Chun, K. S.

1987-01-01

The use of cinematography or holographic interferometry for dynamic flow visualization in an internal combustion engine requires a control device that globally synchronizes camera and light source timing at a predefined shaft encoder angle. The device is capable of 0.35 deg resolution for rotational speeds of up to 73 240 rpm. This was achieved by implementing the shaft encoder signal addressed look-up table (LUT) and appropriate latches. The developed digital signal processing technique achieves 25 nsec of high speed triggering angle detection by using direct parallel bit comparison of the shaft encoder digital code with a simulated angle reference code, instead of using angle value comparison which involves more complicated computation steps. In order to establish synchronization to an AC reference signal whose magnitude is variant with the rotating speed, a dynamic peak followup synchronization technique has been devised. This method scrutinizes the reference signal and provides the right timing within 40 nsec. Two application examples are described.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Chironis, N.P.

This book contains a wealth of valuable information carefully selected and compiled from recent issues of Coal Age magazine. Much of the source material has been gathered by Coal Age Editors during their visits to coal mines, research establishments, universities and technical symposiums. Equally important are the articles and data contributed by over 50 top experts, many of whom are well known to the mining industry. Specifically, this easy-to-use handbook is divided into eleven key areas of underground mining. Here you will find the latest information on continuous mining techniques, longwall and shortwall methods and equipment, specialized mining and boringmore » systems, continuous haulage techniques, improved roof control and ventilation methods, mine communications and instrumentation, power systems, fire control methods, and new mining regulations. There is also a section on engineering and management considerations, including the modern use of computer terminals, practical techniques for picking leaders and for encouraging more safety consciousness in employees, factors affecting absenteeism, and some highly important financial considerations. All of this valuable information has been thoroughly indexed to provide immediate access to the specific data needed by the reader.« less
Feasibility of Stochastic Voltage/VAr Optimization Considering Renewable Energy Resources for Smart Grid

NASA Astrophysics Data System (ADS)

Momoh, James A.; Salkuti, Surender Reddy

2016-06-01

This paper proposes a stochastic optimization technique for solving the Voltage/VAr control problem including the load demand and Renewable Energy Resources (RERs) variation. The RERs often take along some inputs like stochastic behavior. One of the important challenges i. e., Voltage/VAr control is a prime source for handling power system complexity and reliability, hence it is the fundamental requirement for all the utility companies. There is a need for the robust and efficient Voltage/VAr optimization technique to meet the peak demand and reduction of system losses. The voltages beyond the limit may damage costly sub-station devices and equipments at consumer end as well. Especially, the RERs introduces more disturbances and some of the RERs are not even capable enough to meet the VAr demand. Therefore, there is a strong need for the Voltage/VAr control in RERs environment. This paper aims at the development of optimal scheme for Voltage/VAr control involving RERs. In this paper, Latin Hypercube Sampling (LHS) method is used to cover full range of variables by maximally satisfying the marginal distribution. Here, backward scenario reduction technique is used to reduce the number of scenarios effectively and maximally retain the fitting accuracy of samples. The developed optimization scheme is tested on IEEE 24 bus Reliability Test System (RTS) considering the load demand and RERs variation.
Strengths and limitations of molecular subtyping in a community outbreak of Legionnaires' disease.

PubMed

Kool, J L; Buchholz, U; Peterson, C; Brown, E W; Benson, R F; Pruckler, J M; Fields, B S; Sturgeon, J; Lehnkering, E; Cordova, R; Mascola, L M; Butler, J C

2000-12-01

An epidemiological and microbiological investigation of a cluster of eight cases of Legionnaires' disease in Los Angeles County in November 1997 yielded conflicting results. The epidemiological part of the investigation implicated one of several mobile cooling towers used by a film studio in the centre of the outbreak area. However, water sampled from these cooling towers contained L. pneumophila serogroup 1 of another subtype than the strain that was recovered from case-patients in the outbreak. Samples from two cooling towers located downwind from all of the case-patients contained a Legionella strain that was indistinguishable from the outbreak strain by four subtyping techniques (AP-PCR, PFGE, MAb, and MLEE). It is unlikely that these cooling towers were the source of infection for all the case-patients, and they were not associated with risk of disease in the case-control study. The outbreak strain also was not distinguishable, by three subtyping techniques (AP-PCR, PFGE, and MAb), from a L. pneumophila strain that had caused an outbreak in Providence, RI, in 1993. Laboratory cross-contamination was unlikely because the initial subtyping was done in different laboratories. In this investigation, microbiology was helpful for distinguishing the outbreak cluster from unrelated cases of Legionnaires' disease occurring elsewhere. However, multiple subtyping techniques failed to distinguish environmental sources that were probably not associated with the outbreak. Persons investigating Legionnaires' disease outbreaks should be aware that microbiological subtyping does not always identify a source with absolute certainty.
Awareware: Narrowcasting Attributes for Selective Attention, Privacy, and Multipresence

NASA Astrophysics Data System (ADS)

Cohen, Michael; Newton Fernando, Owen Noel

The domain of cscw, computer-supported collaborative work, and DSC, distributed synchronous collaboration, spans real-time interactive multiuser systems, shared information spaces, and applications for teleexistence and artificial reality, including collaborative virtual environments ( cves) (Benford et al., 2001). As presence awareness systems emerge, it is important to develop appropriate interfaces and architectures for managing multimodal multiuser systems. Especially in consideration of the persistent connectivity enabled by affordable networked communication, shared distributed environments require generalized control of media streams, techniques to control source → sink transmissions in synchronous groupware, including teleconferences and chatspaces, online role-playing games, and virtual concerts.
Solar energy control system. [temperature measurement

NASA Technical Reports Server (NTRS)

Currie, J. R. (Inventor)

1981-01-01

A solar energy control system for a hot air type solar energy heating system wherein thermocouples are arranged to sense the temperature of a solar collector, a space to be heated, and a top and bottom of a heat storage unit is disclosed. Pertinent thermocouples are differentially connected together, and these are employed to effect the operation of dampers, a fan, and an auxiliary heat source. In accomplishing this, the differential outputs from the thermocouples are amplified by a single amplifier by multiplexing techniques. Additionally, the amplifier is corrected as to offset by including as one multiplex channel a common reference signal.
Optimal use of electrophysiological indicators of muscular effort and fatigue

NASA Technical Reports Server (NTRS)

Updike, O. L.

1981-01-01

Electromyograms (EMG) from working muscles convey information on effort and fatigue. Their application, e.g., to assess the demands of vehicle control tasks, is complicated by the cooperative action of sets of muscles, by both intrinsic and imposed filtering, and by numerous other sources of variation. Fourier analyses of these noise like signals offer one approach to interpretation; downward spectral shifts accompany fatigue. Techniques are being sought (in both time and frequency domains) for further condensing the wideband EMG signals, while retaining essential information, into a concise 'state vector' usable in comparing control system designs.
Infrared Radiation Filament And Metnod Of Manufacture

DOEpatents

Johnson, Edward A.

1998-11-17

An improved IR radiation source is provided by the invention. A radiation filament has a textured surface produced by seeded ion bombardment of a metal foil which is cut to a serpentine shape and mounted in a windowed housing. Specific ion bombardment texturing techniques tune the surface to maximize emissions in the desired wavelength range and to limit emissions outside that narrow range, particularly at longer wavelengths. A combination of filament surface texture, thickness, material, shape and power circuit feedback control produce wavelength controlled and efficient radiation at much lower power requirements than devices of the prior art.
A modified cementing technique using BoneSource to augment fixation of the acetabulum in a sheep model.

PubMed

Timperley, A John; Nusem, Iulian; Wilson, Kathy; Whitehouse, Sarah L; Buma, Pieter; Crawford, Ross W

2010-08-01

Our aim was to assess in an animal model whether the use of HA paste at the cement-bone interface in the acetabulum improves fixation. We examined, in sheep, the effect of interposing a layer of hydroxyapatite cement around the periphery of a polyethylene socket prior to fixing it using polymethylmethacrylate (PMMA). We performed a randomized study involving 22 sheep that had BoneSource hydroxyapatite material applied to the surface of the acetabulum before cementing a polyethylene cup at arthroplasty. We studied the gross radiographic appearance of the implant-bone interface and the histological appearance at the interface. There were more radiolucencies evident in the control group. Histologically, only sheep randomized into the BoneSource group exhibited a fully osseointegrated interface. Use of the hydroxyapatite material did not give any detrimental effects. In some cases, the material appeared to have been fully resorbed. When the material was evident in histological sections, it was incorporated into an osseointegrated interface. There was no giant cell reaction present. There was no evidence of migration of BoneSource to the articulation. The application of HA material prior to cementation of a socket produced an improved interface. The technique may be useful in humans, to extend the longevity of the cemented implant by protecting the socket interface from the effect of hydrodynamic fluid flow and particulate debris.
The Impact of Pollution Prevention on Toxic Environmental Releases from U.S. Manufacturing Facilities.

PubMed

Ranson, Matthew; Cox, Brendan; Keenan, Cheryl; Teitelbaum, Daniel

2015-11-03

Between 1991 and 2012, the facilities that reported to the U.S. Environmental Protection Agency's Toxic Release Inventory (TRI) Program conducted 370,000 source reduction projects. We use this data set to conduct the first quasi-experimental retrospective evaluation of how implementing a source reduction (pollution prevention) project affects the quantity of toxic chemicals released to the environment by an average industrial facility. We use a differences-in-differences methodology, which measures how implementing a source reduction project affects a facility's releases of targeted chemicals, relative to releases of (a) other untargeted chemicals from the same facility, or (b) the same chemical from other facilities in the same industry. We find that the average source reduction project causes a 9-16% decrease in releases of targeted chemicals in the year of implementation. Source reduction techniques vary in effectiveness: for example, raw material modification causes a large decrease in releases, while inventory control has no detectable effect. Our analysis suggests that in aggregate, the source reduction projects carried out in the U.S. since 1991 have prevented between 5 and 14 billion pounds of toxic releases.
Reducing the ingress of urban noise through natural ventilation openings.

PubMed

Oldham, D J; de Salis, M H; Sharples, S

2004-01-01

For buildings in busy urban areas affected by high levels of road traffic noise the potential to use natural ventilation can be limited by excessive noise entering through ventilation openings. This paper is concerned with techniques to reduce noise ingress into naturally ventilated buildings while minimizing airflow path resistance. A combined experimental and theoretical approach to the interaction of airflow and sound transmission through ventilators for natural ventilation applications is described. A key element of the investigation has been the development of testing facilities capable of measuring the airflow and sound transmission losses for a range of ventilation noise control strategies. It is demonstrated that a combination of sound reduction mechanisms -- one covering low frequency sound and another covering high frequency sound -- is required to attenuate effectively noise from typical urban sources. A method is proposed for quantifying the acoustic performance of different strategies to enable comparisons and informed decisions to be made leading to the possibility of a design methodology for optimizing the ventilation and acoustic performance of different strategies. The need for employing techniques for combating low frequency sound in tandem with techniques for reducing high frequency sound in reducing the ingress of noise from urban sources such as road traffic to acceptable levels is demonstrated. A technique is proposed for enabling the acoustic and airflow performance of apertures for natural ventilation systems to be designed simultaneously.
Holograms for acoustics.

PubMed

Melde, Kai; Mark, Andrew G; Qiu, Tian; Fischer, Peer

2016-09-22

Holographic techniques are fundamental to applications such as volumetric displays, high-density data storage and optical tweezers that require spatial control of intricate optical or acoustic fields within a three-dimensional volume. The basis of holography is spatial storage of the phase and/or amplitude profile of the desired wavefront in a manner that allows that wavefront to be reconstructed by interference when the hologram is illuminated with a suitable coherent source. Modern computer-generated holography skips the process of recording a hologram from a physical scene, and instead calculates the required phase profile before rendering it for reconstruction. In ultrasound applications, the phase profile is typically generated by discrete and independently driven ultrasound sources; however, these can only be used in small numbers, which limits the complexity or degrees of freedom that can be attained in the wavefront. Here we introduce monolithic acoustic holograms, which can reconstruct diffraction-limited acoustic pressure fields and thus arbitrary ultrasound beams. We use rapid fabrication to craft the holograms and achieve reconstruction degrees of freedom two orders of magnitude higher than commercial phased array sources. The technique is inexpensive, appropriate for both transmission and reflection elements, and scales well to higher information content, larger aperture size and higher power. The complex three-dimensional pressure and phase distributions produced by these acoustic holograms allow us to demonstrate new approaches to controlled ultrasonic manipulation of solids in water, and of liquids and solids in air. We expect that acoustic holograms will enable new capabilities in beam-steering and the contactless transfer of power, improve medical imaging, and drive new applications of ultrasound.
Advanced control of neutral beam injected power in DIII-D

DOE PAGES

Pawley, Carl J.; Crowley, Brendan J.; Pace, David C.; ...

2017-03-23

In the DIII-D tokamak, one of the most powerful techniques to control the density, temperature and plasma rotation is by eight independently modulated neutral beam sources with a total power of 20 MW. The rapid modulation requires a high degree of reproducibility and precise control of the ion source plasma and beam acceleration voltage. Recent changes have been made to the controls to provide a new capability to smoothly vary the beam current and beam voltage during a discharge, while maintaining the modulation capability. The ion source plasma inside the arc chamber is controlled through feedback from the Langmuir probesmore » measuring plasma density near the extraction end. To provide the new capability, the plasma control system (PCS) has been enabled to change the Langmuir probe set point and the beam voltage set point in real time. When the PCS varies the Langmuir set point, the plasma density is directly controlled in the arc chamber, thus changing the beam current (perveance) and power going into the tokamak. Alternately, the PCS can sweep the beam voltage set point by 20 kV or more and adjust the Langmuir probe setting to match, keeping the perveance constant and beam divergence at a minimum. This changes the beam power and average neutral particle energy, which changes deposition in the tokamak plasma. The ion separating magnetic field must accurately match the beam voltage to protect the beam line. To do this, the magnet current control accurately tracks the beam voltage set point. In conclusion, these new capabilities allow continuous in-shot variation of neutral beam ion energy to complement« less
Contact Force Compensated Thermal Stimulators for Holistic Haptic Interfaces.

PubMed

Sim, Jai Kyoung; Cho, Young-Ho

2016-05-01

We present a contact force compensated thermal stimulator that can provide a consistent tempera- ture sensation on the human skin independent of the contact force between the thermal stimulator and the skin. Previous passive thermal stimulators were not capable of providing a consistent tem- perature on the human skin even when using identical heat source voltage due to an inconsistency of the heat conduction, which changes due to the force-dependent thermal contact resistance. We propose a force-based feedback method that monitors the contact force and controls the heat source voltage according to this contact force, thus providing consistent temperature on the skin. We composed a heat circuit model equivalent to the skin heat-transfer rate as it is changed by the contact forces; we obtained the optimal voltage condition for the constant skin heat-transfer rate independent of the contact force using a numerical estimation simulation tool. Then, in the experiment, we heated real human skin at the obtained heat source voltage condition, and investigated the skin heat transfer-rate by measuring the skin temperature at various times at different levels of contact force. In the numerical estimation results, the skin heat-transfer rate for the contact forces showed a linear profile in the contact force range of 1-3 N; from this profile we obtained the voltage equation for heat source control. In the experimental study, we adjusted the heat source voltage according to the contact force based on the obtained equation. As a result, without the heat source voltage control for the contact forces, the coefficients of variation (CV) of the skin heat-transfer rate in the contact force range of 1-3 N was found to be 11.9%. On the other hand, with the heat source voltage control for the contact forces, the CV of the skin heat-transfer rate in the contact force range of 1-3 N was found to be barely 2.0%, which indicate an 83.2% improvement in consistency compared to the skin heat-transfer rate without the heat source voltage control. The present technique provides a consistent temperature sensation on the human skin independent of the body movement environment; therefore, it has high potential for use in holistic haptic interfaces that have thermal displays.
Authentication techniques for smart cards

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, R.A.

1994-02-01

Smart card systems are most cost efficient when implemented as a distributed system, which is a system without central host interaction or a local database of card numbers for verifying transaction approval. A distributed system, as such, presents special card and user authentication problems. Fortunately, smart cards offer processing capabilities that provide solutions to authentication problems, provided the system is designed with proper data integrity measures. Smart card systems maintain data integrity through a security design that controls data sources and limits data changes. A good security design is usually a result of a system analysis that provides a thoroughmore » understanding of the application needs. Once designers understand the application, they may specify authentication techniques that mitigate the risk of system compromise or failure. Current authentication techniques include cryptography, passwords, challenge/response protocols, and biometrics. The security design includes these techniques to help prevent counterfeit cards, unauthorized use, or information compromise. This paper discusses card authentication and user identity techniques that enhance security for microprocessor card systems. It also describes the analysis process used for determining proper authentication techniques for a system.« less

Technique for Radiometer and Antenna Array Calibration with Two Antenna Noise Diodes

NASA Technical Reports Server (NTRS)

Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

2011-01-01

This paper presents a new technique to calibrate a microwave radiometer and phased array antenna system. This calibration technique uses a radiated noise source in addition to an injected noise sources for calibration. The plane of reference for this calibration technique is the face of the antenna and therefore can effectively calibration the gain fluctuations in the active phased array antennas. This paper gives the mathematical formulation for the technique and discusses the improvements brought by the method over the existing calibration techniques.
In-situ droplet monitoring for self-tuning spectrometers

DOEpatents

Montaser, Akbar; Jorabchi, Kaveh; Kahen, Kaveh

2010-09-28

A laser scattering based imaging technique is utilized in order to visualize the aerosol droplets in an inductively coupled plasma (ICP) torch from an aerosol source to the site of analytical measurements. The resulting snapshots provide key information about the spatial distribution of the aerosol introduced by direct and indirect injection devices: 1) a direct injection high efficiency nebulizer (DIHEN); 2) a large-bore DIHEN (LB-DIHEN); and 3) a PFA microflow nebulizer with a PFA Scott-type spray chamber. Moreover, particle image velocimetry (PIV) is used to study the in-situ behavior of the aerosol before interaction with, for example, plasma, while the individual surviving droplets are explored by particle tracking velocimetry (PTV). Further, the velocity distribution of the surviving droplets demonstrates the importance of the initial droplet velocities in complete desolvation of the aerosol for optimum analytical performance in ICP spectrometries. These new observations are important in the design of the next-generation direct injection devices for lower sample consumption, higher sensitivity, lower noise levels, suppressed matrix effects, and for developing smart spectrometers. For example, a controller can be provided to control the output of the aerosol source by controlling the configuration of the source or the gas flow rate via feedback information concerning the aerosol.
Coherent X-ray imaging across length scales

NASA Astrophysics Data System (ADS)

Munro, P. R. T.

2017-04-01

Contemporary X-ray imaging techniques span a uniquely wide range of spatial resolutions, covering five orders of magnitude. The evolution of X-ray sources, from the earliest laboratory sources through to highly brilliant and coherent free-electron lasers, has been key to the development of these imaging techniques. This review surveys the predominant coherent X-ray imaging techniques with fields of view ranging from that of entire biological organs, down to that of biomolecules. We introduce the fundamental principles necessary to understand the image formation for each technique as well as briefly reviewing coherent X-ray source development. We present example images acquired using a selection of techniques, by leaders in the field.
A combined approach for the evaluation of a volatile organic compound emissions inventory.

PubMed

Choi, Yu-Jin; Calabrese, Richard V; Ehrman, Sheryl H; Dickerson, Russell R; Stehr, Jeffrey W

2006-02-01

Emissions inventories significantly affect photochemical air quality model performance and the development of effective control strategies. However, there have been very few studies to evaluate their accuracy. Here, to evaluate a volatile organic compound (VOC) emissions inventory, we implemented a combined approach: comparing the ratios of carbon bond (CB)-IV VOC groups to nitrogen oxides (NOx) or carbon monoxide (CO) using an emission preprocessing model, comparing the ratios of VOC source contributions from a source apportionment technique to NOx or CO, and comparing ratios of CB-IV VOC groups to NOx or CO and the absolute concentrations of CB-IV VOC groups using an air quality model, with the corresponding ratios and concentrations observed at three sites (Maryland, Washington, DC, and New Jersey). The comparisons of the ethene/NOx ratio, the xylene group (XYL)/NOx ratio, and ethene and XYL concentrations between estimates and measurements showed some differences, depending on the comparison approach, at the Maryland and Washington, DC sites. On the other hand, consistent results at the New Jersey site were observed, implying a possible overestimation of vehicle exhaust. However, in the case of the toluene group (TOL), which is emitted mainly from surface coating and printing sources in the solvent utilization category, the ratios of TOL/ NOx or CO, as well as the absolute concentrations revealed an overestimate of these solvent sources by a factor of 1.5 to 3 at all three sites. In addition, the overestimate of these solvent sources agreed with the comparisons of surface coating and printing source contributions relative to NOx from a source apportionment technique to the corresponding value of estimates at the Maryland site. Other studies have also suggested an overestimate of solvent sources, implying a possibility of inaccurate emission factors in estimating VOC emissions from surface coating and printing sources. We tested the impact of these overestimates with a chemical transport model and found little change in ozone but substantial changes in calculated secondary organic aerosol concentrations.
Dc microgrid stabilization through fuzzy control of interleaved, heterogeneous storage elements

NASA Astrophysics Data System (ADS)

Smith, Robert David

As microgrid power systems gain prevalence and renewable energy comprises greater and greater portions of distributed generation, energy storage becomes important to offset the higher variance of renewable energy sources and maximize their usefulness. One of the emerging techniques is to utilize a combination of lead-acid batteries and ultracapacitors to provide both short and long-term stabilization to microgrid systems. The different energy and power characteristics of batteries and ultracapacitors imply that they ought to be utilized in different ways. Traditional linear controls can use these energy storage systems to stabilize a power grid, but cannot effect more complex interactions. This research explores a fuzzy logic approach to microgrid stabilization. The ability of a fuzzy logic controller to regulate a dc bus in the presence of source and load fluctuations, in a manner comparable to traditional linear control systems, is explored and demonstrated. Furthermore, the expanded capabilities (such as storage balancing, self-protection, and battery optimization) of a fuzzy logic system over a traditional linear control system are shown. System simulation results are presented and validated through hardware-based experiments. These experiments confirm the capabilities of the fuzzy logic control system to regulate bus voltage, balance storage elements, optimize battery usage, and effect self-protection.
Machine-learning-based diagnosis of schizophrenia using combined sensor-level and source-level EEG features.

PubMed

Shim, Miseon; Hwang, Han-Jeong; Kim, Do-Won; Lee, Seung-Hwan; Im, Chang-Hwan

2016-10-01

Recently, an increasing number of researchers have endeavored to develop practical tools for diagnosing patients with schizophrenia using machine learning techniques applied to EEG biomarkers. Although a number of studies showed that source-level EEG features can potentially be applied to the differential diagnosis of schizophrenia, most studies have used only sensor-level EEG features such as ERP peak amplitude and power spectrum for machine learning-based diagnosis of schizophrenia. In this study, we used both sensor-level and source-level features extracted from EEG signals recorded during an auditory oddball task for the classification of patients with schizophrenia and healthy controls. EEG signals were recorded from 34 patients with schizophrenia and 34 healthy controls while each subject was asked to attend to oddball tones. Our results demonstrated higher classification accuracy when source-level features were used together with sensor-level features, compared to when only sensor-level features were used. In addition, the selected sensor-level features were mostly found in the frontal area, and the selected source-level features were mostly extracted from the temporal area, which coincide well with the well-known pathological region of cognitive processing in patients with schizophrenia. Our results suggest that our approach would be a promising tool for the computer-aided diagnosis of schizophrenia. Copyright © 2016 Elsevier B.V. All rights reserved.
Gesture-Controlled Interface for Contactless Control of Various Computer Programs with a Hooking-Based Keyboard and Mouse-Mapping Technique in the Operating Room

PubMed Central

Park, Ben Joonyeon; Jang, Taekjin; Choi, Jong Woo; Kim, Namkug

2016-01-01

We developed a contactless interface that exploits hand gestures to effectively control medical images in the operating room. We developed an in-house program called GestureHook that exploits message hooking techniques to convert gestures into specific functions. For quantitative evaluation of this program, we used gestures to control images of a dynamic biliary CT study and compared the results with those of a mouse (8.54 ± 1.77 s to 5.29 ± 1.00 s; p < 0.001) and measured the recognition rates of specific gestures and the success rates of tasks based on clinical scenarios. For clinical applications, this program was set up in the operating room to browse images for plastic surgery. A surgeon browsed images from three different programs: CT images from a PACS program, volume-rendered images from a 3D PACS program, and surgical planning photographs from a basic image viewing program. All programs could be seamlessly controlled by gestures and motions. This approach can control all operating room programs without source code modification and provide surgeons with a new way to safely browse through images and easily switch applications during surgical procedures. PMID:26981146
Gesture-Controlled Interface for Contactless Control of Various Computer Programs with a Hooking-Based Keyboard and Mouse-Mapping Technique in the Operating Room.

PubMed

Park, Ben Joonyeon; Jang, Taekjin; Choi, Jong Woo; Kim, Namkug

2016-01-01

We developed a contactless interface that exploits hand gestures to effectively control medical images in the operating room. We developed an in-house program called GestureHook that exploits message hooking techniques to convert gestures into specific functions. For quantitative evaluation of this program, we used gestures to control images of a dynamic biliary CT study and compared the results with those of a mouse (8.54 ± 1.77 s to 5.29 ± 1.00 s; p < 0.001) and measured the recognition rates of specific gestures and the success rates of tasks based on clinical scenarios. For clinical applications, this program was set up in the operating room to browse images for plastic surgery. A surgeon browsed images from three different programs: CT images from a PACS program, volume-rendered images from a 3D PACS program, and surgical planning photographs from a basic image viewing program. All programs could be seamlessly controlled by gestures and motions. This approach can control all operating room programs without source code modification and provide surgeons with a new way to safely browse through images and easily switch applications during surgical procedures.
Capillary plasma jet: A low volume plasma source for life science applications

NASA Astrophysics Data System (ADS)

Topala, I.; Nagatsu, M.

2015-02-01

In this letter, we present results from multispectroscopic analysis of protein films, after exposure to a peculiar plasma source, i.e., the capillary plasma jet. This plasma source is able to generate very small pulsed plasma volumes, in kilohertz range, with characteristic dimensions smaller than 1 mm. This leads to specific microscale generation and transport of all plasma species. Plasma diagnosis was realized using general electrical and optical methods. Depending on power level and exposure duration, this miniature plasma jet can induce controllable modifications to soft matter targets. Detailed discussions on protein film oxidation and chemical etching are supported by results from absorption, X-ray photoelectron spectroscopy, and microscopy techniques. Further exploitation of principles presented here may consolidate research interests involving plasmas in biotechnologies and plasma medicine, especially in patterning technologies, modified biomolecule arrays, and local chemical functionalization.
Py4Syn: Python for synchrotrons.

PubMed

Slepicka, H H; Canova, H F; Beniz, D B; Piton, J R

2015-09-01

In this report, Py4Syn, an open-source Python-based library for data acquisition, device manipulation, scan routines and other helper functions, is presented. Driven by easy-to-use and scalability ideals, Py4Syn offers control system agnostic solution and high customization level for scans and data output, covering distinct techniques and facilities. Here, most of the library functionalities are described, examples of use are shown and ideas for future implementations are presented.
Nonlinear dispersion-based incoherent photonic processing for microwave pulse generation with full reconfigurability.

PubMed

Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

2012-03-12

A novel all-optical technique based on the incoherent processing of optical signals using high-order dispersive elements is analyzed for microwave arbitrary pulse generation. We show an approach which allows a full reconfigurability of a pulse in terms of chirp, envelope and central frequency by the proper control of the second-order dispersion and the incoherent optical source power distribution, achieving large values of time-bandwidth product.
Five Bit, Five Gigasample TED Analog-to-Digital Converter Development.

DTIC Science & Technology

1981-06-01

pliers. TRW uses two sources at present: materials grown by Horizontal I Bridgman technique from Crystal Specialties, and Czochralski from MRI. The...the circuit modelling and circuit design tasks. A number of design iterations were required to arrive at a satisfactory design. In or-der to riake...made by modeling the TELD as a voltage-controlled current generator with a built-in time delay between impressed voltage and output current. Based on
Spectrum Efficiency Through Dynamic Spectrum Access Techniques (Briefing Charts)

DTIC Science & Technology

2014-06-01

Telemetry Data Sources IP BASED TELEMETRY STATION Flow control • Volume- based • Credit- based • Rate- based Signaling using custom protocols or standards...Responsible for all T&E infrastructure assessment within the Major Range and Test Facility Base (MRTFB) DoD Directive 3200.11 • Administer three...Memorandum Unleashing of the Wireless Broadband Revolution THE WHY: Based on the view that “we are now beginning the next transformation in
The low-frequency sound power measuring technique for an underwater source in a non-anechoic tank

NASA Astrophysics Data System (ADS)

Zhang, Yi-Ming; Tang, Rui; Li, Qi; Shang, Da-Jing

2018-03-01

In order to determine the radiated sound power of an underwater source below the Schroeder cut-off frequency in a non-anechoic tank, a low-frequency extension measuring technique is proposed. This technique is based on a unique relationship between the transmission characteristics of the enclosed field and those of the free field, which can be obtained as a correction term based on previous measurements of a known simple source. The radiated sound power of an unknown underwater source in the free field can thereby be obtained accurately from measurements in a non-anechoic tank. To verify the validity of the proposed technique, a mathematical model of the enclosed field is established using normal-mode theory, and the relationship between the transmission characteristics of the enclosed and free fields is obtained. The radiated sound power of an underwater transducer source is tested in a glass tank using the proposed low-frequency extension measuring technique. Compared with the free field, the radiated sound power level of the narrowband spectrum deviation is found to be less than 3 dB, and the 1/3 octave spectrum deviation is found to be less than 1 dB. The proposed testing technique can be used not only to extend the low-frequency applications of non-anechoic tanks, but also for measurement of radiated sound power from complicated sources in non-anechoic tanks.
Implementation of fuzzy-sliding mode based control of a grid connected photovoltaic system.

PubMed

Menadi, Abdelkrim; Abdeddaim, Sabrina; Ghamri, Ahmed; Betka, Achour

2015-09-01

The present work describes an optimal operation of a small scale photovoltaic system connected to a micro-grid, based on both sliding mode and fuzzy logic control. Real time implementation is done through a dSPACE 1104 single board, controlling a boost chopper on the PV array side and a voltage source inverter (VSI) on the grid side. The sliding mode controller tracks permanently the maximum power of the PV array regardless of atmospheric condition variations, while The fuzzy logic controller (FLC) regulates the DC-link voltage, and ensures via current control of the VSI a quasi-total transit of the extracted PV power to the grid under a unity power factor operation. Simulation results, carried out via Matlab-Simulink package were approved through experiment, showing the effectiveness of the proposed control techniques. Copyright © 2015. Published by Elsevier Ltd.
Preliminary analysis of an extensive one year survey of trace elements and compounds in the suspended particulate matter in Cleveland, Ohio

NASA Technical Reports Server (NTRS)

King, R. B.; Fordyce, J. S.; Antoine, A. C.; Leibecki, H. F.; Neustadter, H. E.; Sidik, S. M.; Burr, J. C.; Craig, G. T.; Cornett, C. L.

1974-01-01

Beginning in 1971 a cooperative program has been carried on by the City of Cleveland Division of Air Pollution Control and NASA Lewis Research Center to study the trace element and compound concentrations in the ambient suspended particulate matter in Cleveland Ohio as a function of source, monitoring location and meteorological conditions. The major objectives were to determine the ambient concentration levels at representative urban sites and to develop a technique using trace element and compound data in conjunction with meteorological conditions to identify specific pollution sources which could be developed into a practical system that could be readily utilized by an enforcement agency.
History of surgery for atrial fibrillation.

PubMed

Edgerton, Zachary J; Edgerton, James R

2009-12-01

There is a rich history of surgery for atrial fibrillation. Initial procedures were aimed at controlling the ventricular response rate. Later procedures were directed at converting atrial fibrillation to normal sinus rhythm. These culminated in the Cox Maze III procedure. While highly effective, the complexity and morbidity of the cut and sew Maze III limited its adoption. Enabling technology has developed alternate energy sources designed to produce a transmural atrial scar without cutting and sewing. Termed the Maze IV, this lessened the morbidity of the procedure and widened the applicability. Further advances in minimal access techniques are now being developed to allow totally thorascopic placement of all the left atrial lesions on the full, beating heart, using alternate energy sources.
Efficient optical cloud removal technique for earth observation based on MOEMs device

NASA Astrophysics Data System (ADS)

Zamkotsian, Frédéric; Lanzoni, Patrick; Liotard, Arnaud; Viard, Thierry; Noell, Wilfried

2017-11-01

In Earth Observation instruments, observation of scenes including bright sources leads to an important degradation of the recorded signal. We propose a new concept to remove dynamically the bright sources and then obtain a field of view with an optically enhanced Signal-to-Noise Ratio (SNR). Micro-Opto-Electro-Mechanical Systems (MOEMS) could be key components in future generation of space instruments. MOEMS-based programmable slit masks will permit the straylight control in future Earth Observation instruments. Experimental demonstration of this concept has been conducted on a dedicated bench. This successful first demonstration shows the high potential of this new concept in future spectro-imager for Earth Observation.
APTI Course 450, Source Sampling for Particulate Pollutants. Instructor's Guide.

ERIC Educational Resources Information Center

Aldina, G. J.; And Others

This manual covers a four and one half day laboratory course in source sampling for particulates. The course presents principles and techniques necessary for performing isokinetic source sampling procedures. Lectures cover formulas dealing with basic fluid mechanics appropriate to the techniques employed. Laboratory exercises are intended to…
Assessment and application of clustering techniques to atmospheric particle number size distribution for the purpose of source apportionment

NASA Astrophysics Data System (ADS)

Salimi, F.; Ristovski, Z.; Mazaheri, M.; Laiman, R.; Crilley, L. R.; He, C.; Clifford, S.; Morawska, L.

2014-06-01

Long-term measurements of particle number size distribution (PNSD) produce a very large number of observations and their analysis requires an efficient approach in order to produce results in the least possible time and with maximum accuracy. Clustering techniques are a family of sophisticated methods which have been recently employed to analyse PNSD data, however, very little information is available comparing the performance of different clustering techniques on PNSD data. This study aims to apply several clustering techniques (i.e. K-means, PAM, CLARA and SOM) to PNSD data, in order to identify and apply the optimum technique to PNSD data measured at 25 sites across Brisbane, Australia. A new method, based on the Generalised Additive Model (GAM) with a basis of penalised B-splines, was proposed to parameterise the PNSD data and the temporal weight of each cluster was also estimated using the GAM. In addition, each cluster was associated with its possible source based on the results of this parameterisation, together with the characteristics of each cluster. The performances of four clustering techniques were compared using the Dunn index and silhouette width validation values and the K-means technique was found to have the highest performance, with five clusters being the optimum. Therefore, five clusters were found within the data using the K-means technique. The diurnal occurrence of each cluster was used together with other air quality parameters, temporal trends and the physical properties of each cluster, in order to attribute each cluster to its source and origin. The five clusters were attributed to three major sources and origins, including regional background particles, photochemically induced nucleated particles and vehicle generated particles. Overall, clustering was found to be an effective technique for attributing each particle size spectra to its source and the GAM was suitable to parameterise the PNSD data. These two techniques can help researchers immensely in analysing PNSD data for characterisation and source apportionment purposes.

Assessment and application of clustering techniques to atmospheric particle number size distribution for the purpose of source apportionment

NASA Astrophysics Data System (ADS)

Salimi, F.; Ristovski, Z.; Mazaheri, M.; Laiman, R.; Crilley, L. R.; He, C.; Clifford, S.; Morawska, L.

2014-11-01

Long-term measurements of particle number size distribution (PNSD) produce a very large number of observations and their analysis requires an efficient approach in order to produce results in the least possible time and with maximum accuracy. Clustering techniques are a family of sophisticated methods that have been recently employed to analyse PNSD data; however, very little information is available comparing the performance of different clustering techniques on PNSD data. This study aims to apply several clustering techniques (i.e. K means, PAM, CLARA and SOM) to PNSD data, in order to identify and apply the optimum technique to PNSD data measured at 25 sites across Brisbane, Australia. A new method, based on the Generalised Additive Model (GAM) with a basis of penalised B-splines, was proposed to parameterise the PNSD data and the temporal weight of each cluster was also estimated using the GAM. In addition, each cluster was associated with its possible source based on the results of this parameterisation, together with the characteristics of each cluster. The performances of four clustering techniques were compared using the Dunn index and Silhouette width validation values and the K means technique was found to have the highest performance, with five clusters being the optimum. Therefore, five clusters were found within the data using the K means technique. The diurnal occurrence of each cluster was used together with other air quality parameters, temporal trends and the physical properties of each cluster, in order to attribute each cluster to its source and origin. The five clusters were attributed to three major sources and origins, including regional background particles, photochemically induced nucleated particles and vehicle generated particles. Overall, clustering was found to be an effective technique for attributing each particle size spectrum to its source and the GAM was suitable to parameterise the PNSD data. These two techniques can help researchers immensely in analysing PNSD data for characterisation and source apportionment purposes.
Precision calibration of the silicon doping level in gallium arsenide epitaxial layers

NASA Astrophysics Data System (ADS)

Mokhov, D. V.; Berezovskaya, T. N.; Kuzmenkov, A. G.; Maleev, N. A.; Timoshnev, S. N.; Ustinov, V. M.

2017-10-01

An approach to precision calibration of the silicon doping level in gallium arsenide epitaxial layers is discussed that is based on studying the dependence of the carrier density in the test GaAs layer on the silicon- source temperature using the Hall-effect and CV profiling techniques. The parameters are measured by standard or certified measuring techniques and approved measuring instruments. It is demonstrated that the use of CV profiling for controlling the carrier density in the test GaAs layer at the thorough optimization of the measuring procedure ensures the highest accuracy and reliability of doping level calibration in the epitaxial layers with a relative error of no larger than 2.5%.
Highly selective deuteration of pharmaceutically relevant nitrogen-containing heterocycles: a flow chemistry approach.

PubMed

Ötvös, Sándor B; Mándity, István M; Fülöp, Ferenc

2011-08-01

A simple and efficient flow-based technique is reported for the catalytic deuteration of several model nitrogen-containing heterocyclic compounds which are important building blocks of pharmacologically active materials. A continuous flow reactor was used in combination with on-demand pressure-controlled electrolytic D(2) production. The D(2) source was D(2)O, the consumption of which was very low. The experimental set-up allows the fine-tuning of pressure, temperature, and flow rate so as to determine the optimal conditions for the deuteration reactions. The described procedure lacks most of the drawbacks of the conventional batch deuteration techniques, and additionally is highly selective and reproducible.
Ultrafast X-Ray Coherent Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reis, David

2009-05-01

This main purpose of this grant was to develop the nascent eld of ultrafast x-ray science using accelerator-based sources, and originally developed from an idea that a laser could modulate the di racting properties of a x-ray di racting crystal on a fast enough time scale to switch out in time a shorter slice from the already short x-ray pulses from a synchrotron. The research was carried out primarily at the Advanced Photon Source (APS) sector 7 at Argonne National Laboratory and the Sub-Picosecond Pulse Source (SPPS) at SLAC; in anticipation of the Linac Coherent Light Source (LCLS) x-ray freemore » electron laser that became operational in 2009 at SLAC (all National User Facilities operated by BES). The research centered on the generation, control and measurement of atomic-scale dynamics in atomic, molecular optical and condensed matter systems with temporal and spatial resolution . It helped develop the ultrafast physics, techniques and scienti c case for using the unprecedented characteristics of the LCLS. The project has been very successful with results have been disseminated widely and in top journals, have been well cited in the eld, and have laid the foundation for many experiments being performed on the LCLS, the world's rst hard x-ray free electron laser.« less
Storm Event Suspended Sediment-Discharge Hysteresis and Controls in Agricultural Watersheds: Implications for Watershed Scale Sediment Management.

PubMed

Sherriff, Sophie C; Rowan, John S; Fenton, Owen; Jordan, Philip; Melland, Alice R; Mellander, Per-Erik; hUallacháin, Daire Ó

2016-02-16

Within agricultural watersheds suspended sediment-discharge hysteresis during storm events is commonly used to indicate dominant sediment sources and pathways. However, availability of high-resolution data, qualitative metrics, longevity of records, and simultaneous multiwatershed analyses has limited the efficacy of hysteresis as a sediment management tool. This two year study utilizes a quantitative hysteresis index from high-resolution suspended sediment and discharge data to assess fluctuations in sediment source location, delivery mechanisms and export efficiency in three intensively farmed watersheds during events over time. Flow-weighted event sediment export was further considered using multivariate techniques to delineate rainfall, stream hydrology, and antecedent moisture controls on sediment origins. Watersheds with low permeability (moderately- or poorly drained soils) with good surface hydrological connectivity, therefore, had contrasting hysteresis due to source location (hillslope versus channel bank). The well-drained watershed with reduced connectivity exported less sediment but, when watershed connectivity was established, the largest event sediment load of all watersheds occurred. Event sediment export was elevated in arable watersheds when low groundcover was coupled with high connectivity, whereas in the grassland watershed, export was attributed to wetter weather only. Hysteresis analysis successfully indicated contrasting seasonality, connectivity and source availability and is a useful tool to identify watershed specific sediment management practices.
A stroboscopic technique for using CCD cameras in flow visualization systems for continuous viewing and stop action photography

NASA Technical Reports Server (NTRS)

Franke, John M.; Rhodes, David B.; Jones, Stephen B.; Dismond, Harriet R.

1992-01-01

A technique for synchronizing a pulse light source to charge coupled device cameras is presented. The technique permits the use of pulse light sources for continuous as well as stop action flow visualization. The technique has eliminated the need to provide separate lighting systems at facilities requiring continuous and stop action viewing or photography.
The Application of Coherent Local Time for Optical Time Transfer and the Quantification of Systematic Errors in Satellite Laser Ranging

NASA Astrophysics Data System (ADS)

Schreiber, K. Ulrich; Kodet, Jan

2018-02-01

Highly precise time and stable reference frequencies are fundamental requirements for space geodesy. Satellite laser ranging (SLR) is one of these techniques, which differs from all other applications like Very Long Baseline Interferometry (VLBI), Global Navigation Satellite Systems (GNSS) and finally Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) by the fact that it is an optical two-way measurement technique. That means that there is no need for a clock synchronization process between both ends of the distance covered by the measurement technique. Under the assumption of isotropy for the speed of light, SLR establishes the only practical realization of the Einstein Synchronization process so far. Therefore it is a powerful time transfer technique. However, in order to transfer time between two remote clocks, it is also necessary to tightly control all possible signal delays in the ranging process. This paper discusses the role of time and frequency in SLR as well as the error sources before it address the transfer of time between ground and space. The need of an improved signal delay control led to a major redesign of the local time and frequency distribution at the Geodetic Observatory Wettzell. Closure measurements can now be used to identify and remove systematic errors in SLR measurements.
Emerging Preservation Techniques for Controlling Spoilage and Pathogenic Microorganisms in Fruit Juices

PubMed Central

Aneja, Kamal Rai; Dhiman, Romika; Aggarwal, Neeraj Kumar; Aneja, Ashish

2014-01-01

Fruit juices are important commodities in the global market providing vast possibilities for new value added products to meet consumer demand for convenience, nutrition, and health. Fruit juices are spoiled primarily due to proliferation of acid tolerant and osmophilic microflora. There is also risk of food borne microbial infections which is associated with the consumption of fruit juices. In order to reduce the incidence of outbreaks, fruit juices are preserved by various techniques. Thermal pasteurization is used commercially by fruit juice industries for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. Nonthermal pasteurization methods such as high hydrostatic pressure, pulsed electric field, and ultrasound and irradiations have also been employed in fruit juices to overcome the negative effects of thermal pasteurization. Some of these techniques have already been commercialized. Some are still in research or pilot scale. Apart from these emerging techniques, preservatives from natural sources have also shown considerable promise for use in some food products. In this review article, spoilage, pathogenic microflora, and food borne outbreaks associated with fruit juices of last two decades are given in one section. In other sections various prevention methods to control the growth of spoilage and pathogenic microflora to increase the shelf life of fruit juices are discussed. PMID:25332721
QPA-CLIPS: A language and representation for process control

NASA Technical Reports Server (NTRS)

Freund, Thomas G.

1994-01-01

QPA-CLIPS is an extension of CLIPS oriented towards process control applications. Its constructs define a dependency network of process actions driven by sensor information. The language consists of three basic constructs: TASK, SENSOR, and FILTER. TASK's define the dependency network describing alternative state transitions for a process. SENSOR's and FILTER's define sensor information sources used to activate state transitions within the network. Deftemplate's define these constructs and their run-time environment is an interpreter knowledge base, performing pattern matching on sensor information and so activating TASK's in the dependency network. The pattern matching technique is based on the repeatable occurrence of a sensor data pattern. QPA-CIPS has been successfully tested on a SPARCStation providing supervisory control to an Allen-Bradley PLC 5 controller driving molding equipment.
Brain glucose sensing in homeostatic and hedonic regulation.

PubMed

Steinbusch, Laura; Labouèbe, Gwenaël; Thorens, Bernard

2015-09-01

Glucose homeostasis as well as homeostatic and hedonic control of feeding is regulated by hormonal, neuronal, and nutrient-related cues. Glucose, besides its role as a source of metabolic energy, is an important signal controlling hormone secretion and neuronal activity, hence contributing to whole-body metabolic integration in coordination with feeding control. Brain glucose sensing plays a key, but insufficiently explored, role in these metabolic and behavioral controls, which when deregulated may contribute to the development of obesity and diabetes. The recent introduction of innovative transgenic, pharmacogenetic, and optogenetic techniques allows unprecedented analysis of the complexity of central glucose sensing at the molecular, cellular, and neuronal circuit levels, which will lead to a new understanding of the pathogenesis of metabolic diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.
Optimal Dynamic Sub-Threshold Technique for Extreme Low Power Consumption for VLSI

NASA Technical Reports Server (NTRS)

Duong, Tuan A.

2012-01-01

For miniaturization of electronics systems, power consumption plays a key role in the realm of constraints. Considering the very large scale integration (VLSI) design aspect, as transistor feature size is decreased to 50 nm and below, there is sizable increase in the number of transistors as more functional building blocks are embedded in the same chip. However, the consequent increase in power consumption (dynamic and leakage) will serve as a key constraint to inhibit the advantages of transistor feature size reduction. Power consumption can be reduced by minimizing the voltage supply (for dynamic power consumption) and/or increasing threshold voltage (V(sub th), for reducing leakage power). When the feature size of the transistor is reduced, supply voltage (V(sub dd)) and threshold voltage (V(sub th)) are also reduced accordingly; then, the leakage current becomes a bigger factor of the total power consumption. To maintain low power consumption, operation of electronics at sub-threshold levels can be a potentially strong contender; however, there are two obstacles to be faced: more leakage current per transistor will cause more leakage power consumption, and slow response time when the transistor is operated in weak inversion region. To enable low power consumption and yet obtain high performance, the CMOS (complementary metal oxide semiconductor) transistor as a basic element is viewed and controlled as a four-terminal device: source, drain, gate, and body, as differentiated from the traditional approach with three terminals: i.e., source and body, drain, and gate. This technique features multiple voltage sources to supply the dynamic control, and uses dynamic control to enable low-threshold voltage when the channel (N or P) is active, for speed response enhancement and high threshold voltage, and when the transistor channel (N or P) is inactive, to reduce the leakage current for low-leakage power consumption.
Monitoring fugitive methane and natural gas emissions, validation of measurement techniques.

NASA Astrophysics Data System (ADS)

Robinson, Rod; Innocenti, Fabrizio; Gardiner, Tom; Helmore, Jon; Finlayson, Andrew; Connor, Andy

2017-04-01

The detection and quantification of fugitive and diffuse methane emissions has become an increasing priority in recent years. As the requirements for routine measurement to support industry initiatives increase there is a growing requirement to assess and validate the performance of fugitive emission measurement technologies. For reported emissions traceability and comparability of measurements is important. This talk will present recent work addressing these needs. Differential Absorption Lidar (DIAL) is a laser based remote sensing technology, able to map the concentration of gases in the atmosphere and determine emission fluxes for fugitive emissions. A description of the technique and its application for determining fugitive emissions of methane from oil and gas operations and waste management sites will be given. As DIAL has gained acceptance as a powerful tool for the measurement and quantification of fugitive emissions, and given the rich data it produces, it is being increasingly used to assess and validate other measurement approaches. In addition, to support the validation of technologies, we have developed a portable controlled release facility able to simulate the emissions from area sources. This has been used to assess and validate techniques which are used to monitor emissions. The development and capabilities of the controlled release facility will be described. This talk will report on recent studies using DIAL and the controlled release facility to validate fugitive emission measurement techniques. This includes side by side comparisons of two DIAL systems, the application of both the DIAL technique and the controlled release facility in a major study carried out in 2015 by South Coast Air Quality Management District (SCAQMD) in which a number of optical techniques were assessed and the development of a prototype method validation approach for techniques used to measure methane emissions from shale gas sites. In conclusion the talk will provide an update on the current status in the development of a European Standard for the measurement of fugitive emissions of VOCs and the use of validation data in the standardisation process and discuss the application of this to methane measurement.
Design and Analysis Tools for Concurrent Blackboard Systems

NASA Technical Reports Server (NTRS)

McManus, John W.

1991-01-01

A blackboard system consists of a set of knowledge sources, a blackboard data structure, and a control strategy used to activate the knowledge sources. The blackboard model of problem solving is best described by Dr. H. Penny Nii of the Stanford University AI Laboratory: "A Blackboard System can be viewed as a collection of intelligent agents who are gathered around a blackboard, looking at pieces of information written on it, thinking about the current state of the solution, and writing their conclusions on the blackboard as they generate them. " The blackboard is a centralized global data structure, often partitioned in a hierarchical manner, used to represent the problem domain. The blackboard is also used to allow inter-knowledge source communication and acts as a shared memory visible to all of the knowledge sources. A knowledge source is a highly specialized, highly independent process that takes inputs from the blackboard data structure, performs a computation, and places the results of the computation in the blackboard data structure. This design allows for an opportunistic control strategy. The opportunistic problem-solving technique allows a knowledge source to contribute towards the solution of the current problem without knowing which of the other knowledge sources will use the information. The use of opportunistic problem-solving allows the data transfers on the blackboard to determine which processes are active at a given time. Designing and developing blackboard systems is a difficult process. The designer is trying to balance several conflicting goals and achieve a high degree of concurrent knowledge source execution while maintaining both knowledge and semantic consistency on the blackboard. Blackboard systems have not attained their apparent potential because there are no established tools or methods to guide in their construction or analyze their performance.
Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

NASA Astrophysics Data System (ADS)

Kar, S.; Ahmed, H.; Nersisyan, G.; Brauckmann, S.; Hanton, F.; Giesecke, A. L.; Naughton, K.; Willi, O.; Lewis, C. L. S.; Borghesi, M.

2016-05-01

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ˜20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from a laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.
Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Nersisyan, G.

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ∼20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from amore » laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.« less
Development of at-wavelength metrology for x-ray optics at the ALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Yuan, Sheng

2010-07-09

The comprehensive realization of the exciting advantages of new third- and forth-generation synchrotron radiation light sources requires concomitant development of reflecting and diffractive x-ray optics capable of micro- and nano-focusing, brightness preservation, and super high resolution. The fabrication, tuning, and alignment of the optics are impossible without adequate metrology instrumentation, methods, and techniques. While the accuracy of ex situ optical metrology at the Advanced Light Source (ALS) has reached a state-of-the-art level, wavefront control on beamlines is often limited by environmental and systematic alignment factors, and inadequate in situ feedback. At ALS beamline 5.3.1, we are developing broadly applicable, high-accuracy,more » in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of tests with increasing accuracy and sensitivity. Geometric Hartmann tests, performed with a scanning illuminated sub-aperture determine the wavefront slope across the full mirror aperture. Shearing interferometry techniques use coherent illumination and provide higher sensitivity wavefront measurements. Combining these techniques with high precision optical metrology and experimental methods will enable us to provide in situ setting and alignment of bendable x-ray optics to realize diffraction-limited, sub 50 nm focusing at beamlines. We describe here details of the metrology beamline endstation, the x-ray beam diagnostic system, and original experimental techniques that have already allowed us to precisely set a bendable KB mirror to achieve a focused spot size of 150 nm.« less
Use of the Drawing-Writing Technique to Determine the Level of Knowledge of Pre-Service Teachers Regarding Renewable Energy Sources

ERIC Educational Resources Information Center

Kara, Filiz

2015-01-01

The aim of this study was to determine the level of knowledge of pre-service science teachers in Turkey regarding the different types of renewable energy sources, the methods used for obtaining energy from these sources, and the areas of use for these energy sources. Within the context of the study, the drawing-writing technique was used in order…
Sediment data sources and estimated annual suspended-sediment loads of rivers and streams in Colorado

USGS Publications Warehouse

Elliott, J.G.; DeFeyter, K.L.

1986-01-01

Sources of sediment data collected by several government agencies through water year 1984 are summarized for Colorado. The U.S. Geological Survey has collected suspended-sediment data at 243 sites; these data are stored in the U.S. Geological Survey 's water data storage and retrieval system. The U.S. Forest Service has collected suspended-sediment and bedload data at an additional 225 sites, and most of these data are stored in the U.S. Environmental Protection Agency 's water-quality-control information system. Additional unpublished sediment data are in the possession of the collecting entities. Annual suspended-sediment loads were computed for 133 U.S. Geological Survey sediment-data-collection sites using the daily mean water-discharge/sediment-transport-curve method. Sediment-transport curves were derived for each site by one of three techniques: (1) Least-squares linear regression of all pairs of suspended-sediment and corresponding water-discharge data, (2) least-squares linear regression of data sets subdivided on the basis of hydrograph season; and (3) graphical fit to a logarithm-logarithm plot of data. The curve-fitting technique used for each site depended on site-specific characteristics. Sediment-data sources and estimates of annual loads of suspended, bed, and total sediment from several other reports also are summarized. (USGS)
Frequency and time domain three-dimensional inversion of electromagnetic data for a grounded-wire source

NASA Astrophysics Data System (ADS)

Sasaki, Yutaka; Yi, Myeong-Jong; Choi, Jihyang; Son, Jeong-Sul

2015-01-01

We present frequency- and time-domain three-dimensional (3-D) inversion approaches that can be applied to transient electromagnetic (TEM) data from a grounded-wire source using a PC. In the direct time-domain approach, the forward solution and sensitivity were obtained in the frequency domain using a finite-difference technique, and the frequency response was then Fourier-transformed using a digital filter technique. In the frequency-domain approach, TEM data were Fourier-transformed using a smooth-spectrum inversion method, and the recovered frequency response was then inverted. The synthetic examples show that for the time derivative of magnetic field, frequency-domain inversion of TEM data performs almost as well as time-domain inversion, with a significant reduction in computational time. In our synthetic studies, we also compared the resolution capabilities of the ground and airborne TEM and controlled-source audio-frequency magnetotelluric (CSAMT) data resulting from a common grounded wire. An airborne TEM survey at 200-m elevation achieved a resolution for buried conductors almost comparable to that of the ground TEM method. It is also shown that the inversion of CSAMT data was able to detect a 3-D resistivity structure better than the TEM inversion, suggesting an advantage of electric-field measurements over magnetic-field-only measurements.
Analysis of heavy metal sources in soil using kriging interpolation on principal components.

PubMed

Ha, Hoehun; Olson, James R; Bian, Ling; Rogerson, Peter A

2014-05-06

Anniston, Alabama has a long history of operation of foundries and other heavy industry. We assessed the extent of heavy metal contamination in soils by determining the concentrations of 11 heavy metals (Pb, As, Cd, Cr, Co, Cu, Mn, Hg, Ni, V, and Zn) based on 2046 soil samples collected from 595 industrial and residential sites. Principal Component Analysis (PCA) was adopted to characterize the distribution of heavy metals in soil in this region. In addition, a geostatistical technique (kriging) was used to create regional distribution maps for the interpolation of nonpoint sources of heavy metal contamination using geographical information system (GIS) techniques. There were significant differences found between sampling zones in the concentrations of heavy metals, with the exception of the levels of Ni. Three main components explaining the heavy metal variability in soils were identified. The results suggest that Pb, Cd, Cu, and Zn were associated with anthropogenic activities, such as the operations of some foundries and major railroads, which released these heavy metals, whereas the presence of Co, Mn, and V were controlled by natural sources, such as soil texture, pedogenesis, and soil hydrology. In general terms, the soil levels of heavy metals analyzed in this study were higher than those reported in previous studies in other industrial and residential communities.

CSI-EPT in Presence of RF-Shield for MR-Coils.

PubMed

Arduino, Alessandro; Zilberti, Luca; Chiampi, Mario; Bottauscio, Oriano

2017-07-01

Contrast source inversion electric properties tomography (CSI-EPT) is a recently developed technique for the electric properties tomography that recovers the electric properties distribution starting from measurements performed by magnetic resonance imaging scanners. This method is an optimal control approach based on the contrast source inversion technique, which distinguishes itself from other electric properties tomography techniques for its capability to recover also the local specific absorption rate distribution, essential for online dosimetry. Up to now, CSI-EPT has only been described in terms of integral equations, limiting its applicability to homogeneous unbounded background. In order to extend the method to the presence of a shield in the domain-as in the recurring case of shielded radio frequency coils-a more general formulation of CSI-EPT, based on a functional viewpoint, is introduced here. Two different implementations of CSI-EPT are proposed for a 2-D transverse magnetic model problem, one dealing with an unbounded domain and one considering the presence of a perfectly conductive shield. The two implementations are applied on the same virtual measurements obtained by numerically simulating a shielded radio frequency coil. The results are compared in terms of both electric properties recovery and local specific absorption rate estimate, in order to investigate the requirement of an accurate modeling of the underlying physical problem.
Intelligent control for PMSM based on online PSO considering parameters change

NASA Astrophysics Data System (ADS)

Song, Zhengqiang; Yang, Huiling

2018-03-01

A novel online particle swarm optimization method is proposed to design speed and current controllers of vector controlled interior permanent magnet synchronous motor drives considering stator resistance variation. In the proposed drive system, the space vector modulation technique is employed to generate the switching signals for a two-level voltage-source inverter. The nonlinearity of the inverter is also taken into account due to the dead-time, threshold and voltage drop of the switching devices in order to simulate the system in the practical condition. Speed and PI current controller gains are optimized with PSO online, and the fitness function is changed according to the system dynamic and steady states. The proposed optimization algorithm is compared with conventional PI control method in the condition of step speed change and stator resistance variation, showing that the proposed online optimization method has better robustness and dynamic characteristics compared with conventional PI controller design.
Stabilization of Particle Discrimination Efficiencies for Neutron Spectrum Unfolding With Organic Scintillators

NASA Astrophysics Data System (ADS)

Lawrence, Chris C.; Polack, J. K.; Febbraro, Michael; Kolata, J. J.; Flaska, Marek; Pozzi, S. A.; Becchetti, F. D.

2017-02-01

The literature discussing pulse-shape discrimination (PSD) in organic scintillators dates back several decades. However, little has been written about PSD techniques that are optimized for neutron spectrum unfolding. Variation in n-γ misclassification rates and in γ/n ratio of incident fields can distort the neutron pulse-height response of scintillators and these distortions can in turn cause large errors in unfolded spectra. New applications in arms-control verification call for detection of lower-energy neutrons, for which PSD is particularly problematic. In this article, we propose techniques for removing distortions on pulse-height response that result from the merging of PSD distributions in the low-pulse-height region. These techniques take advantage of the repeatable shapes of PSD distributions that are governed by the counting statistics of scintillation-photon populations. We validate the proposed techniques using accelerator-based time-of-flight measurements and then demonstrate them by unfolding the Watt spectrum from measurement with a 252Cf neutron source.
Changes of soil functional diversity induced by the use of different fertilizers

NASA Astrophysics Data System (ADS)

Onica, Bogdan-Mihai; Sandor, Valentina; Brad, Traian; Vidican, Roxana; Sandor, Mignon

2017-04-01

Agricultural practices like fertilization can change the structure and function of soil microbial community. Monitoring and assessing the soil microbiota and its dynamic related to different factors can be a powerful tool for understanding basic and applied ecological contexts. An important tool to assess changes of community level physiological profile is MicroResp, a colorimetric method that uses a 96-well microtitre plate, 16 carbon sources and a detection plate to quantify the respiratory activity of the soil microbial community. The main objective of this work is to assess the changes of the community level physiological profile when different fertilizers were used. In order to achieve this goal, a microcosm experiment was designed and performed under controlled temperature and humidity, and the soil samples were analyzed using the MicroResp technique. The experiment was designed with two types of soil (chernozem and luvisol), four types of fertilizers (mineral fertilizer, mustard as green manure, slurry manure and cattle manure) with three replicates for each and a control. Soil samples analyzed with MicroResp technique were prepared and loaded into the deep-well plates and incubated for six hours at 25 oC with the 15 carbon sources which were used at the concentration of 30 mg g-1 soil H2O, one in each well and water as control. The detection plates were read with a spectrophotometer before and after six hours incubation at a wavelength of 570 nm. Highest respiratory activity between the two types of soil used in experiment was given by the luvisol compared with chernozem. Regarding to the differences between the types of fertilizers, we observed that the highest microbial metabolic activity was given by green manure followed in order by cattle manure, slurry manure, control and mineral fertilizer with the lowest respiratory values. This pattern was same for both soils. However, highest respiratory activity was given by α-ketoglutaric acid, malic acid, oxalic acid, citric acid carbon sources, while the lowest respiratory activity was obtained in case of arginine.
Accounting for uncertainty in model-based prevalence estimation: paratuberculosis control in dairy herds.

PubMed

Davidson, Ross S; McKendrick, Iain J; Wood, Joanna C; Marion, Glenn; Greig, Alistair; Stevenson, Karen; Sharp, Michael; Hutchings, Michael R

2012-09-10

A common approach to the application of epidemiological models is to determine a single (point estimate) parameterisation using the information available in the literature. However, in many cases there is considerable uncertainty about parameter values, reflecting both the incomplete nature of current knowledge and natural variation, for example between farms. Furthermore model outcomes may be highly sensitive to different parameter values. Paratuberculosis is an infection for which many of the key parameter values are poorly understood and highly variable, and for such infections there is a need to develop and apply statistical techniques which make maximal use of available data. A technique based on Latin hypercube sampling combined with a novel reweighting method was developed which enables parameter uncertainty and variability to be incorporated into a model-based framework for estimation of prevalence. The method was evaluated by applying it to a simulation of paratuberculosis in dairy herds which combines a continuous time stochastic algorithm with model features such as within herd variability in disease development and shedding, which have not been previously explored in paratuberculosis models. Generated sample parameter combinations were assigned a weight, determined by quantifying the model's resultant ability to reproduce prevalence data. Once these weights are generated the model can be used to evaluate other scenarios such as control options. To illustrate the utility of this approach these reweighted model outputs were used to compare standard test and cull control strategies both individually and in combination with simple husbandry practices that aim to reduce infection rates. The technique developed has been shown to be applicable to a complex model incorporating realistic control options. For models where parameters are not well known or subject to significant variability, the reweighting scheme allowed estimated distributions of parameter values to be combined with additional sources of information, such as that available from prevalence distributions, resulting in outputs which implicitly handle variation and uncertainty. This methodology allows for more robust predictions from modelling approaches by allowing for parameter uncertainty and combining different sources of information, and is thus expected to be useful in application to a large number of disease systems.
New techniques to control salinity-wastewater reuse interactions in golf courses of the Mediterranean regions

NASA Astrophysics Data System (ADS)

Beltrao, J.; Costa, M.; Rosado, V.; Gamito, P.; Santos, R.; Khaydarova, V.

2003-04-01

Due to the lack water around the Mediterranean regions, potable water luxurious uses - as in golf courses - are increasingly contested. In order to solve this problem, non conventional water resources (effluent, gray, recycled, reclaimed, brackish), like treated wastewater, for irrigation gained increasing role in the planning and development of additional water supplies in golf courses. In most cases, the intense use of effluent for irrigation attracted public awareness in respect of contaminating pathogens and heavy metals. The contaminating effect of salinity in soil and underground water is very often neglected. The objective of this work is to present the conventional techniques to control salinity of treated wastewater and to present some results on new clean techniques to solve this problem, in the framework of the INCO-COPERNICUS project (no. IC-15CT98-0105) "Adaptation of Efficient Water Use Criteria in Marginal Regions of Europe and Middle Asia with Scarce Sources Subject to Environmental Control, Climate Change and Socio-Economic Development" and of the INCO-DC project (no. IC18-CT98-0266) "Control of Salination and Combating Desertification Effects in the Mediterranean Region. Phase II". Saline water is the most common irrigation water in arid climates. Moreover, for each region treated wastewater is always more saline than tap water, and therefore, when treated wastewater is reused in golf courses, more salinity problems occur. Conventional techniques to combat the salination process in golf courses can be characterized by four generations: 1) Problem of root zone salination by soil leaching - two options can occur - when there is an impermeable layer, salts will be concentrated above this layer; on the other hand, when there is no impermeable layer, aquifers contamination can be observed; 2) Use of subsurface trickle irrigation - economy of water, and therefore less additional salts; however the problem of groundwater contamination due to natural rain or artificial leaching remained; 3) Enhanced fertilization increases turfgrass tolerance to salinity, but the contamination will be increased by other hazardous chemicals such as nitrate; 4) Use of salt tolerant turfgrass species this technique will be very useful to the plants, but does not solve the problem os soil or groundwater contamination. When reusing treated wastewater in the Mediterranean areas, the only way to control the salination process and to maintain the sustainability of golf courses is to combat the salination problems by environmentally safe and clean techniques. These new clean techniques include: 1) Use of salt removing turfgrass species; 2) Use of drought tolerant turfgrass species - reduction of salt application by deficit irrigation; 3) Reuse of minimal levels of wastewater enough to obtain a good visual appearance GVA of the turfgrass. Regarding these new clean techniques, experiments were carried out in golf courses of Algarve, Portugal, the most southwest part of Europe. It was shown: 1) Use of salt removing turfgrass species - 3 sprinkle irrigated cultivars were studied (Agrostis solonífera L.; Cynodon dactylon, L. and Penninsetum clandestinum Hochst ex Chiov). 2) Use of drought tolerant turfgrass species -responses to several levels of sprinkle irrigation wastewater and potable water (with and without fertilization). An experimental design, known as sprinkle point source was specially used to simulate the several levels of water application, expressed by the crop coefficient kc and by the crop evapotranspiration rate ETc. Turfgrass yield was enhanced linearly with the increased application of treated wastewater. 3) Reuse of minimal levels of wastewater enough to obtain a good visual appearance GVA of the turfgrass - The minimal crop coefficient kc for a good visual appearance GVA of the turfgrass was around 1.0 to potable water irrigated mixed cultivars (with 30 kg nitrogen ha-1 month-1) and 1.2 to wastewater irrigated Bermuda grass (without any mineral fertilization). As concluding remarks, our results show that these new clean techniques are a strong and powerful tool to control salinity and to avoid soil salination and to maintain sustainability of golf courses.
Joint spectral characterization of photon-pair sources

NASA Astrophysics Data System (ADS)

Zielnicki, Kevin; Garay-Palmett, Karina; Cruz-Delgado, Daniel; Cruz-Ramirez, Hector; O'Boyle, Michael F.; Fang, Bin; Lorenz, Virginia O.; U'Ren, Alfred B.; Kwiat, Paul G.

2018-06-01

The ability to determine the joint spectral properties of photon pairs produced by the processes of spontaneous parametric downconversion (SPDC) and spontaneous four-wave mixing (SFWM) is crucial for guaranteeing the usability of heralded single photons and polarization-entangled pairs for multi-photon protocols. In this paper, we compare six different techniques that yield either a characterization of the joint spectral intensity or of the closely related purity of heralded single photons. These six techniques include: (i) scanning monochromator measurements, (ii) a variant of Fourier transform spectroscopy designed to extract the desired information exploiting a resource-optimized technique, (iii) dispersive fibre spectroscopy, (iv) stimulated-emission-based measurement, (v) measurement of the second-order correlation function ? for one of the two photons, and (vi) two-source Hong-Ou-Mandel interferometry. We discuss the relative performance of these techniques for the specific cases of a SPDC source designed to be factorable and SFWM sources of varying purity, and compare the techniques' relative advantages and disadvantages.
Quick Vegas: Improving Performance of TCP Vegas for High Bandwidth-Delay Product Networks

NASA Astrophysics Data System (ADS)

Chan, Yi-Cheng; Lin, Chia-Liang; Ho, Cheng-Yuan

An important issue in designing a TCP congestion control algorithm is that it should allow the protocol to quickly adjust the end-to-end communication rate to the bandwidth on the bottleneck link. However, the TCP congestion control may function poorly in high bandwidth-delay product networks because of its slow response with large congestion windows. In this paper, we propose an enhanced version of TCP Vegas called Quick Vegas, in which we present an efficient congestion window control algorithm for a TCP source. Our algorithm improves the slow-start and congestion avoidance techniques of original Vegas. Simulation results show that Quick Vegas significantly improves the performance of connections as well as remaining fair when the bandwidth-delay product increases.
NOx control techniques for the CPI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambert, D.; McGowan, T.F.

1996-06-01

After years of air pollution control innovation, the control of emissions of nitrogen oxide compounds stands out as an area where much work remains to be performed in the chemical process industries (CPI). Federal regulations, ozone non-attainment areas, acid rain provisions of the US Clean Air Act, and corporate goals for emission reductions are all motivators. Primary CPI sources are high-temperature combustion systems, including fired heaters, boilers and Kilns. Nitrogen-based processes such as nitric acid manufacture also contribute. The paper discusses the regulations which define the problem and some solutions. These include fuel switching, low-excess air burners, fluegas recirculation, stagedmore » combustion, out of service burners, and wet scrubbing of flue gas. The paper briefly discusses costs of these options.« less
Amputation rehabilitation and prosthetic restoration. From surgery to community reintegration.

PubMed

Esquenazi, Alberto

The purpose of this review is to summarize the literature related to the advances that have taken place in the management and rehabilitation care of limb amputation. Prostheses for the lower and upper limb amputee have changed greatly over the past several years, with advances in components, socket fabrication and fitting techniques, suspension systems and sources of power and electronic controls. Higher levels of limb amputation can now be fitted with functional prostheses, which allow more patients to achieve independent life styles. This is of particular importance for the multi-limb amputee. The rehabilitation of more traditional lower limb levels of amputation have also greatly benefited from the technological advances including energy storing feet, electronic control hydraulic knees, ankle rotators and shock absorbers to mention a few. For the upper limb amputee, myoelectric and proportional controlled terminal devices and elbow joints are now used routinely in some rehabilitation facilities. Experimental prosthetic fitting techniques and devices such as the use of osseo-implantation for suspension of the prosthesis, tension control hands or electromagnetic fluids for knee movement control will also be briefly discussed in this paper. It is possible to conclude from this review that many advances have occurred that have greatly impacted the functional outcomes of patients with limb amputation.
Technology for large space systems: A bibliography with indexes (supplement 11)

NASA Technical Reports Server (NTRS)

1985-01-01

This bibliography contains 539 abstracts of reports, articles and other documents introduced into the NASA scientific and technical information system between January 1, 1984 and December 31, 1984. Abstracts are arranged in the following categories: systems; analysis and design techniques; structural concepts; structural and thermal analysis; structural dynamics and control; electronics; advanced materials; assembly concepts; propulsion; and miscellaneous. Subject, personal author, corporate source, contract number, report number, and accession number indexes are listed.
Design Issues for Traffic Management for the ATM UBR + Service for TCP Over Satellite Networks

NASA Technical Reports Server (NTRS)

Jain, Raj

1999-01-01

This project was a comprehensive research program for developing techniques for improving the performance of Internet protocols over Asynchronous Transfer Mode (ATM) based satellite networks. Among the service categories provided by ATM networks, the most commonly used category for data traffic is the unspecified bit rate (UBR) service. UBR allows sources to send data into the network without any feedback control. The project resulted in the numerous ATM Forum contributions and papers.
Quality Control Studies of Wavelength Shifting Fibers for a Scintillator-Based Tail Catcher Muon Tracker for Linear Collider Prototype Detector

NASA Astrophysics Data System (ADS)

Dyshkant, A.; Beznosko, D.; Blazey, G.; Fisk, E.; Hahn, E.; Rykalin, V.; Wayne, M.; Zutshi, V.

2006-12-01

Detailed measurements of the wavelength shifting fiber response to a stable and reliable light source are presented. Particulars about materials, a double reference method, and measurement technique are included. The fibers studied were several hundred Kuraray, Y-11, multiclad, 1.2-mm outer diameter wavelength shifting fibers, each cut from a reel to about one meter length. The fibers were polished, mirrored, and the mirrors were UV epoxy protected. Each fiber passed quality control requirements before installation. About 94% of the fibers tested have a response within 1% of the overall mean
Spatial characterization of dissolved trace elements and heavy metals in the upper Han River (China) using multivariate statistical techniques.

PubMed

Li, Siyue; Zhang, Quanfa

2010-04-15

A data matrix (4032 observations), obtained during a 2-year monitoring period (2005-2006) from 42 sites in the upper Han River is subjected to various multivariate statistical techniques including cluster analysis, principal component analysis (PCA), factor analysis (FA), correlation analysis and analysis of variance to determine the spatial characterization of dissolved trace elements and heavy metals. Our results indicate that waters in the upper Han River are primarily polluted by Al, As, Cd, Pb, Sb and Se, and the potential pollutants include Ba, Cr, Hg, Mn and Ni. Spatial distribution of trace metals indicates the polluted sections mainly concentrate in the Danjiang, Danjiangkou Reservoir catchment and Hanzhong Plain, and the most contaminated river is in the Hanzhong Plain. Q-model clustering depends on geographical location of sampling sites and groups the 42 sampling sites into four clusters, i.e., Danjiang, Danjiangkou Reservoir region (lower catchment), upper catchment and one river in headwaters pertaining to water quality. The headwaters, Danjiang and lower catchment, and upper catchment correspond to very high polluted, moderate polluted and relatively low polluted regions, respectively. Additionally, PCA/FA and correlation analysis demonstrates that Al, Cd, Mn, Ni, Fe, Si and Sr are controlled by natural sources, whereas the other metals appear to be primarily controlled by anthropogenic origins though geogenic source contributing to them. 2009 Elsevier B.V. All rights reserved.
Occurrence of bacteriophages infecting Aeromonas, Enterobacter, and Klebsiella in water and association with contamination sources in Thailand.

PubMed

Wangkahad, Bencharong; Bosup, Suchada; Mongkolsuk, Skorn; Sirikanchana, Kwanrawee

2015-06-01

The co-residence of bacteriophages and their bacterial hosts in humans, animals, and environmental sources directed the use of bacteriophages to track the origins of the pathogenic bacteria that can be found in contaminated water. The objective of this study was to enumerate bacteriophages of Aeromonas caviae (AecaKS148), Enterobacter sp. (EnspKS513), and Klebsiella pneumoniae (KlpnKS648) in water and evaluate their association with contamination sources (human vs. animals). Bacterial host strains were isolated from untreated wastewater in Bangkok, Thailand. A double-layer agar technique was used to detect bacteriophages. All three bacteriophages were detected in polluted canal samples, with likely contamination from human wastewater, whereas none was found in non-polluted river samples. AecaKS148 was found to be associated with human fecal sources, while EnspKS513 and KlpnKS648 seemed to be equally prevalent in both human and animal fecal sources. Both bacteriophages were also present in polluted canals that could receive contamination from other fecal sources or the environment. In conclusion, all three bacteriophages were successfully monitored in Bangkok, Thailand. This study provided an example of bacteriophages for potential use as source identifiers of pathogen contamination. The results from this study will assist in controlling sources of pathogen contamination, especially in developing countries.
Centralized light-source optical access network based on polarization multiplexing.

PubMed

Grassi, Fulvio; Mora, José; Ortega, Beatriz; Capmany, José

2010-03-01

This paper presents and demonstrates a centralized light source optical access network based on optical polarization multiplexing technique. By using two optical sources emitting light orthogonally polarized in the Central Node for downstream and upstream operations, the Remote Node is kept source-free. EVM values below telecommunication standard requirements have been measured experimentally when bidirectional digital signals have been transmitted over 10 km of SMF employing subcarrier multiplexing technique in the electrical domain.
Application of simple adaptive control to water hydraulic servo cylinder system

NASA Astrophysics Data System (ADS)

Ito, Kazuhisa; Yamada, Tsuyoshi; Ikeo, Shigeru; Takahashi, Koji

2012-09-01

Although conventional model reference adaptive control (MRAC) achieves good tracking performance for cylinder control, the controller structure is much more complicated and has less robustness to disturbance in real applications. This paper discusses the use of simple adaptive control (SAC) for positioning a water hydraulic servo cylinder system. Compared with MRAC, SAC has a simpler and lower order structure, i.e., higher feasibility. The control performance of SAC is examined and evaluated on a water hydraulic servo cylinder system. With the recent increased concerns over global environmental problems, the water hydraulic technique using pure tap water as a pressure medium has become a new drive source comparable to electric, oil hydraulic, and pneumatic drive systems. This technique is also preferred because of its high power density, high safety against fire hazards in production plants, and easy availability. However, the main problems for precise control in a water hydraulic system are steady state errors and overshoot due to its large friction torque and considerable leakage flow. MRAC has been already applied to compensate for these effects, and better control performances have been obtained. However, there have been no reports on the application of SAC for water hydraulics. To make clear the merits of SAC, the tracking control performance and robustness are discussed based on experimental results. SAC is confirmed to give better tracking performance compared with PI control, and a control precision comparable to MRAC (within 10 μm of the reference position) and higher robustness to parameter change, despite the simple controller. The research results ensure a wider application of simple adaptive control in real mechanical systems.
Near Real-Time Imaging of the Galactic Plane with BATSE

NASA Technical Reports Server (NTRS)

Harmon, B. A.; Zhang, S. N.; Robinson, C. R.; Paciesas, W. S.; Barret, D.; Grindlay, J.; Bloser, P.; Monnelly, C.

1997-01-01

The discovery of new transient or persistent sources in the hard X-ray regime with the BATSE Earth occultation Technique has been limited previously to bright sources of about 200 mCrab or more. While monitoring known source locations is not a problem to a daily limiting sensitivity of about 75 mCrab, the lack of a reliable background model forces us to use more intensive computer techniques to find weak, previously unknown emission from hard X-ray/gamma sources. The combination of Radon transform imaging of the galactic plane in 10 by 10 degree fields and the Harvard/CFA-developed Image Search (CBIS) allows us to straightforwardly search the sky for candidate sources in a +/- 20 degree latitude band along the plane. This procedure has been operating routinely on a weekly basis since spring 1997. We briefly describe the procedure, then concentrate on the performance aspects of the technique and candidate source results from the search.
Methods and systems for remote detection of gases

DOEpatents

Johnson, Timothy J.

2007-11-27

Novel systems and methods for remotely detecting at least one constituent of a gas via infrared detection are provided. A system includes at least one extended source of broadband infrared radiation and a spectrally sensitive receiver positioned remotely from the source. The source and the receiver are oriented such that a surface of the source is in the field of view of the receiver. The source includes a heating component thermally coupled to the surface, and the heating component is configured to heat the surface to a temperature above ambient temperature. The receiver is operable to collect spectral infrared absorption data representative of a gas present between the source and the receiver. The invention advantageously overcomes significant difficulties associated with active infrared detection techniques known in the art, and provides an infrared detection technique with a much greater sensitivity than passive infrared detection techniques known in the art.
Methods and systems for remote detection of gases

DOEpatents

Johnson, Timothy J

2012-09-18

Novel systems and methods for remotely detecting at least one constituent of a gas via infrared detection are provided. A system includes at least one extended source of broadband infrared radiation and a spectrally sensitive receiver positioned remotely from the source. The source and the receiver are oriented such that a surface of the source is in the field of view of the receiver. The source includes a heating component thermally coupled to the surface, and the heating component is configured to heat the surface to a temperature above ambient temperature. The receiver is operable to collect spectral infrared absorption data representative of a gas present between the source and the receiver. The invention advantageously overcomes significant difficulties associated with active infrared detection techniques known in the art, and provides an infrared detection technique with a much greater sensitivity than passive infrared detection techniques known in the art.

Heralded quantum repeater based on the scattering of photons off single emitters using parametric down-conversion source.

PubMed

Song, Guo-Zhu; Wu, Fang-Zhou; Zhang, Mei; Yang, Guo-Jian

2016-06-28

Quantum repeater is the key element in quantum communication and quantum information processing. Here, we investigate the possibility of achieving a heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides. We design the compact quantum circuits for nonlocal entanglement generation, entanglement swapping, and entanglement purification, and discuss the feasibility of our protocols with current experimental technology. In our scheme, we use a parametric down-conversion source instead of ideal single-photon sources to realize the heralded quantum repeater. Moreover, our protocols can turn faulty events into the detection of photon polarization, and the fidelity can reach 100% in principle. Our scheme is attractive and scalable, since it can be realized with artificial solid-state quantum systems. With developed experimental technique on controlling emitter-waveguide systems, the repeater may be very useful in long-distance quantum communication.
Heralded quantum repeater based on the scattering of photons off single emitters using parametric down-conversion source

PubMed Central

Song, Guo-Zhu; Wu, Fang-Zhou; Zhang, Mei; Yang, Guo-Jian

2016-01-01

Quantum repeater is the key element in quantum communication and quantum information processing. Here, we investigate the possibility of achieving a heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides. We design the compact quantum circuits for nonlocal entanglement generation, entanglement swapping, and entanglement purification, and discuss the feasibility of our protocols with current experimental technology. In our scheme, we use a parametric down-conversion source instead of ideal single-photon sources to realize the heralded quantum repeater. Moreover, our protocols can turn faulty events into the detection of photon polarization, and the fidelity can reach 100% in principle. Our scheme is attractive and scalable, since it can be realized with artificial solid-state quantum systems. With developed experimental technique on controlling emitter-waveguide systems, the repeater may be very useful in long-distance quantum communication. PMID:27350159
Observations of flat-spectrum radio sources at λ850μm from the James Clerk Maxwell Telescope II. April 2000 to June 2005

NASA Astrophysics Data System (ADS)

Jenness, T.; Robson, E. I.; Stevens, J. A.

2010-01-01

Calibrated data for 143 flat-spectrum extragalactic radio sources are presented at a wavelength of 850μm covering a 5-yr period from 2000 April. The data, obtained at the James Clerk Maxwell Telescope using the Submillimetre Common-User Bolometer Array (SCUBA) camera in pointing mode, were analysed using an automated pipeline process based on the Observatory Reduction and Acquisition Control - Data Reduction (ORAC-DR) system. This paper describes the techniques used to analyse and calibrate the data, and presents the data base of results along with a representative sample of the better-sampled light curves. A re-analysis of previously published data from 1997 to 2000 is also presented. The combined catalogue, comprising 10493 flux density measurements, provides a unique and valuable resource for studies of extragalactic radio sources.
Marked Campylobacteriosis Decline after Interventions Aimed at Poultry, New Zealand

PubMed Central

Sears, Ann; Wilson, Nick; Marshall, Jonathan; Muellner, Petra; Campbell, Donald M.; Lake, Robin J.; French, Nigel P.

2011-01-01

Beginning in the 1980s, New Zealand experienced rising annual rates of campylobacteriosis that peaked in 2006. We analyzed notification, hospitalization, and other data to explore the 2007–2008 drop in campylobacteriosis incidence. Source attribution techniques based on genotyping of Campylobacter jejuni isolates from patients and environmental sources were also used to examine the decline. In 2008, the annual campylobacteriosis notification rate was 161.5/100,000 population, representing a 54% decline compared with the average annual rate of 353.8/100,000 for 2002–2006. A similar decline was seen for hospitalizations. Source attribution findings demonstrated a 74% (95% credible interval 49%–94%) reduction in the number of cases attributed to poultry. These reductions coincided with the introduction of a range of voluntary and regulatory interventions to reduce Campylobacter spp. contamination of poultry. The apparent success of these interventions may inform approaches other countries could consider to help control foodborne campylobacteriosis. PMID:21749761
Adaptive near-field beamforming techniques for sound source imaging.

PubMed

Cho, Yong Thung; Roan, Michael J

2009-02-01

Phased array signal processing techniques such as beamforming have a long history in applications such as sonar for detection and localization of far-field sound sources. Two sometimes competing challenges arise in any type of spatial processing; these are to minimize contributions from directions other than the look direction and minimize the width of the main lobe. To tackle this problem a large body of work has been devoted to the development of adaptive procedures that attempt to minimize side lobe contributions to the spatial processor output. In this paper, two adaptive beamforming procedures-minimum variance distorsionless response and weight optimization to minimize maximum side lobes--are modified for use in source visualization applications to estimate beamforming pressure and intensity using near-field pressure measurements. These adaptive techniques are compared to a fixed near-field focusing technique (both techniques use near-field beamforming weightings focusing at source locations estimated based on spherical wave array manifold vectors with spatial windows). Sound source resolution accuracies of near-field imaging procedures with different weighting strategies are compared using numerical simulations both in anechoic and reverberant environments with random measurement noise. Also, experimental results are given for near-field sound pressure measurements of an enclosed loudspeaker.
Design methodology and results evaluation of a heating functionality in modular lab-on-chip systems

NASA Astrophysics Data System (ADS)

Streit, Petra; Nestler, Joerg; Shaporin, Alexey; Graunitz, Jenny; Otto, Thomas

2018-06-01

Lab-on-a-chip (LoC) systems offer the opportunity of fast and customized biological analyses executed at the ‘point-of-need’ without expensive lab equipment. Some biological processes need a temperature treatment. Therefore, it is important to ensure a defined and stable temperature distribution in the biosensor area. An integrated heating functionality is realized with discrete resistive heating elements including temperature measurement. The focus of this contribution is a design methodology and evaluation technique of the temperature distribution in the biosensor area with regard to the thermal-electrical behaviour of the heat sources. Furthermore, a sophisticated control of the biosensor temperature is proposed. A finite element (FE) model with one and more integrated heat sources in a polymer-based LoC system is used to investigate the impact of the number and arrangement of heating elements on the temperature distribution around the heating elements and in the biosensor area. Based on this model, various LOC systems are designed and fabricated. Electrical characterization of the heat sources and independent temperature measurements with infrared technique are performed to verify the model parameters and prove the simulation approach. The FE model and the proposed methodology is the foundation for optimization and evaluation of new designs with regard to temperature requirements of the biosensor. Furthermore, a linear dependency of the heater temperature on the electric current is demonstrated in the targeted temperature range of 20 °C to 70 °C enabling the usage of the heating functionality for biological reactions requiring a steady-state temperature up to 70 °C. The correlation between heater and biosensor area temperature is derived for a direct control through the heating current.
Broadband geophysical time series data from a stressed environment

NASA Astrophysics Data System (ADS)

Pun, W.; Saleh, R.; Zwaan, D.; Milkereit, B.; Valley, B.; Pilz, M.; Milkereit, C.; Milkereit, R.

2011-12-01

As classical exploration geophysical tools and techniques find new application in time lapse and monitoring studies, a fresh look at the performance and repeatability of various geophysical techniques is worth to take a closer look. We used an active, deep mine site close to Sudbury (Canada) for 3D deployment of broadband geophysical sensors for passive monitoring and detecting anomalous regions in the earth based on physical rock properties. In addition, we conducted controlled source experiments to evaluate repeatability of geophysical sources. To extend from detection to monitoring, continuous repeated measurements are necessary over a long period of time. If a controlled source is stable, the convolution problem is simplified such that any variation in the geophysical data is an effect of the earth's response. Repeated measurements are important for in-mine use to provide a better insight of stress and strain changes due to natural events and mining processes. The development, build-up and redistribution of stress lead to rock failures that can have disastrous consequences if they occur in an uncontrolled manner. In this project, different continuous and repeated in-situ geophysical measurements from a deep underground mine were analyzed to validate the feasibility of in-mine monitoring. Data acquisition tests covered both active and passive methods: gravity meter, fibre optic strain meters, fixed and portable three-component seismic arrays, EM induction coils and borehole based DC/IP resistivity sensors. The newly acquired data cover a wide range of frequencies which allow the study of short- and long-period events, ranging from 10-5 Hz to 10 kHz. Earth tides, global seismic events, tremors, acoustic emissions (microseismic events) and blasts were recorded within a 3D volume.
A study on thermal damage during hyperthermia treatment based on DPL model for multilayer tissues using finite element Legendre wavelet Galerkin approach.

PubMed

Kumar, Dinesh; Rai, K N

2016-12-01

Hyperthermia is a process that uses heat from the spatial heat source to kill cancerous cells without damaging the surrounding healthy tissues. Efficacy of hyperthermia technique is related to achieve temperature at the infected cells during the treatment process. A mathematical model on heat transfer in multilayer tissues in finite domain is proposed to predict the control temperature profile at hyperthermia position. The treatment technique uses dual-phase-lag model of heat transfer in multilayer tissues with modified Gaussian distribution heat source subjected to the most generalized boundary condition and interface at the adjacent layers. The complete dual-phase-lag model of bioheat transfer is solved using finite element Legendre wavelet Galerkin approach. The present solution has been verified with exact solution in a specific case and provides a good accuracy. The effect of the variability of different parameters such as lagging times, external heat source, metabolic heat source and the most generalized boundary condition on temperature profile in multilayer tissues is analyzed and also discussed the effective approach of hyperthermia treatment. Furthermore, we studied the modified thermal damage model with regeneration of healthy tissues as well. For viewpoint of thermal damage, the least thermal damage has been observed in boundary condition of second kind. The article concludes with a discussion of better opportunities for future clinical application of hyperthermia treatment. Copyright Â© 2016 Elsevier Ltd. All rights reserved.
Physiologic Cryoamputation in Managing Critically Ill Patients with Septic, Advanced Acute Limb Ischemia.

PubMed

Chen, Samuel L; Kuo, Isabella J; Kabutey, Nii-Kabu; Fujitani, Roy M

2017-07-01

Certain critically ill patients with advanced acute limb ischemia with a nonviable extremity may be unsuitable for transport to the operating room to undergo definitive amputation. In these unstable patients, rapid regional cryotherapy allows for prompt infectious source control and correction of hemodynamic and metabolic abnormalities, thereby lessening the risk associated with definitive surgical amputation. We describe our refined technique for lower extremity physiologic cryoamputation and review our institutional experience. After adequate analgesia is administered to the patient, a heating pad is secured circumferentially at the proximal amputation margin and the affected extremity is placed in a customized Styrofoam cooler. A circumferential seal is secured at the proximal chill zone without use of a tourniquet and dry ice is placed into the cooler to surround the entire affected leg. Delayed definitive lower extremity amputation is later performed when hemodynamic and metabolic derangements are corrected. We reviewed 5 patients who underwent lower extremity cryoamputation with this technique identified at our institution between 2005 and 2015. Age ranged from 31 to 79 years old. All presented with severe foot infection and septic shock requiring vasopressor support. All 5 patients stabilized hemodynamically following the initial cryoamputation and later underwent definitive lower extremity amputation, with a median time of 3 days following initial cryoamputation. Lower extremity physiologic cryoamputation is an effective, immediate bedside procedure that can provide local source control and the opportunity for correction of metabolic derangements in initially unstable patients to lessen the risk for definitive major lower extremity amputation. Refinement of the cryoamputation technique, as described in this report, allows for a predictable and reproducible physiologic amputation. Copyright © 2017 Elsevier Inc. All rights reserved.
Technique for Radiometer and Antenna Array Calibration with a Radiated Noise Diode

NASA Technical Reports Server (NTRS)

Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

2009-01-01

This paper presents a new technique to calibrate a microwave radiometer and antenna array system. This calibration technique uses a radiated noise source in addition to two calibration sources internal to the radiometer. The method accurately calibrates antenna arrays with embedded active devices (such as amplifiers) which are used extensively in active phased array antennas.
KINETICS OF LOW SOURCE REACTOR STARTUPS. PART II

DOE Office of Scientific and Technical Information (OSTI.GOV)

hurwitz, H. Jr.; MacMillan, D.B.; Smith, J.H.

1962-06-01

A computational technique is described for computation of the probability distribution of power level for a low source reactor startup. The technique uses a mathematical model, for the time-dependent probability distribution of neutron and precursor concentration, having finite neutron lifetime, one group of delayed neutron precursors, and no spatial dependence. Results obtained by the technique are given. (auth)
Research to support sterile-male-release and genetic alteration techniques for sea lamprey control

USGS Publications Warehouse

Bergstedt, Roger A.; Twohey, Michael B.

2007-01-01

Integrated pest management of sea lampreys in the Laurentian Great Lakes has recently been enhanced by addition of a sterile-male-release program, and future developments in genetic approaches may lead to additional methods for reducing sea lamprey reproduction. We review the development, implementation, and evaluation of the sterile-male-release technique (SMRT) as it is being applied against sea lampreys in the Great Lakes, review the current understanding of SMRT efficacy, and identify additional research areas and topics that would increase either the efficacy of the SMRT or expand its geographic potential for application. Key areas for additional research are in the sterilization process, effects of skewed sex ratios on mating behavior, enhancing attractiveness of sterilized males, techniques for genetic alteration of sea lampreys, and sources of animals to enhance or expand the use of sterile lampreys.
Importance of differential charging for controlling both natural and induced vehicle potentials on ATS-5 and ATS-6

NASA Technical Reports Server (NTRS)

Whipple, E. C.; Olsen, R. C.

1980-01-01

Three techniques of discharging satellites used on the P78-2 satellite were the ejection of a beam of electrons from an electron gun; the emission of electrons from a heated, biased filament; and the ejection of a plasma containing energetic positive xenon ions and low energy electrons. When the P78-2 satellite ground to plasma potential difference reached several hundred volts, each of the three techniques was able to completely discharge the satellite. The comparative effctiveness of the techniques were clearly shown. Two days later, the satellite charged to -8 keV upon entering eclipse. The electron gun, emitting 1 mA of electrons with 150 eV energy, reduced the difference in potential between satellite ground and the ambient plasma to -1 kV, but could not completely discharge the satellite. The plasma source completely discharged the satellite.
Deposition And Characterization of (Ti,Zr)N Thin Films Grown Through PAPVD By The Pulsed Arc Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marulanda, D. M.; Trujillo, O.; Devia, A.

The Plasma Assisted Physic Vapor Deposition (PAPVD) by the pulsed arc technique has been used for deposition of Titanium Zirconium Nitride (Ti,Zr)N coatings, using a segmented target of TiZr. The deposition was performed in a vacuum chamber with two faced electrodes (target and substrate) using nitrogen as working gas, and a power-controlled source used to produce the arc discharges. Films were deposited on stainless steel 304, and they were characterized using the X-Ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), Energy Dispersion Spectroscopy (EDS) and Scanning Probe Microscopy (SPM) techniques. The XRD patterns show different planes in which the film grows.more » Through SPM, using Atomic Force Microscopy (AFM) and Lateral Force Microscopy (LFM) modes, a nanotribologic study of the thin film was made, determining hardness and friction coefficient.« less
Time-resolved two-window measurement of Wigner functions for coherent backscatter from a turbid medium

NASA Astrophysics Data System (ADS)

Reil, Frank; Thomas, John E.

2002-05-01

For the first time we are able to observe the time-resolved Wigner function of enhanced backscatter from a random medium using a novel two-window technique. This technique enables us to directly verify the phase-conjugating properties of random media. An incident divergent beam displays a convergent enhanced backscatter cone. We measure the joint position and momentum (x, p) distributions of the light field as a function of propagation time in the medium. The two-window technique allows us to independently control the resolutions for position and momentum, thereby surpassing the uncertainty limit associated with Fourier transform pairs. By using a low-coherence light source in a heterodyne detection scheme, we observe enhanced backscattering resolved by path length in the random medium, providing information about the evolution of optical coherence as a function of penetration depth in the random medium.
Coherent fiber supercontinuum for biophotonics

PubMed Central

Tu, Haohua; Boppart, Stephen A.

2013-01-01

Biophotonics and nonlinear fiber optics have traditionally been two independent fields. Since the discovery of fiber-based supercontinuum generation in 1999, biophotonics applications employing incoherent light have experienced a large impact from nonlinear fiber optics, primarily because of the access to a wide range of wavelengths and a uniform spatial profile afforded by fiber supercontinuum. However, biophotonics applications employing coherent light have not benefited from the most well-known techniques of supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, and inadequate portability. Fortunately, a few key techniques involving nonlinear fiber optics and femtosecond laser development have emerged to overcome these critical limitations. Despite their relative independence, these techniques are the focus of this review, because they can be integrated into a low-cost portable biophotonics source platform. This platform can be shared across many different areas of research in biophotonics, enabling new applications such as point-of-care coherent optical biomedical imaging. PMID:24358056
Passive coherent location direct signal suppression using hardware mixing techniques

NASA Astrophysics Data System (ADS)

Kaiser, Sean A.; Christianson, Andrew J.; Narayanan, Ram M.

2017-05-01

Passive coherent location (PCL) is a radar technique, in which the system uses reflections from opportunistic illumination sources in the environment for detection and tracking. Typically, PCL uses civilian communication transmitters not ideally suited for radar. The physical geometry of PCL is developed on the basis of bistatic radar without control of the transmitter antenna or waveform design. This poses the problem that often the receiver is designed with two antennas and channels, one for reference and one for surveillance. The surveillance channel is also contaminated with the direct signal and thus direct signal suppression (DSS) techniques must be used. This paper proposes an analytical solution based around hardware for DSS which is compared to other methods available in the literature. The methods are tested in varying bistatic geometries and with varying target radar cross section (RCS) and signal-to-noise ratio (SNR).
Software error detection

NASA Technical Reports Server (NTRS)

Buechler, W.; Tucker, A. G.

1981-01-01

Several methods were employed to detect both the occurrence and source of errors in the operational software of the AN/SLQ-32. A large embedded real time electronic warfare command and control system for the ROLM 1606 computer are presented. The ROLM computer provides information about invalid addressing, improper use of privileged instructions, stack overflows, and unimplemented instructions. Additionally, software techniques were developed to detect invalid jumps, indices out of range, infinte loops, stack underflows, and field size errors. Finally, data are saved to provide information about the status of the system when an error is detected. This information includes I/O buffers, interrupt counts, stack contents, and recently passed locations. The various errors detected, techniques to assist in debugging problems, and segment simulation on a nontarget computer are discussed. These error detection techniques were a major factor in the success of finding the primary cause of error in 98% of over 500 system dumps.
Evaluation and study of advanced optical contamination, deposition, measurement, and removal techniques. [including computer programs and ultraviolet reflection analysis

NASA Technical Reports Server (NTRS)

Linford, R. M. F.; Allen, T. H.; Dillow, C. F.

1975-01-01

A program is described to design, fabricate and install an experimental work chamber assembly (WCA) to provide a wide range of experimental capability. The WCA incorporates several techniques for studying the kinetics of contaminant films and their effect on optical surfaces. It incorporates the capability for depositing both optical and contaminant films on temperature-controlled samples, and for in-situ measurements of the vacuum ultraviolet reflectance. Ellipsometer optics are mounted on the chamber for film thickness determinations, and other features include access ports for radiation sources and instrumentation. Several supporting studies were conducted to define specific chamber requirements, to determine the sensitivity of the measurement techniques to be incorporated in the chamber, and to establish procedures for handling samples prior to their installation in the chamber. A bibliography and literature survey of contamination-related articles is included.
Acoustic impulse response method as a source of undergraduate research projects and advanced laboratory experiments.

PubMed

Robertson, W M; Parker, J M

2012-03-01

A straightforward and inexpensive implementation of acoustic impulse response measurement is described utilizing the signal processing technique of coherent averaging. The technique is capable of high signal-to-noise measurements with personal computer data acquisition equipment, an amplifier/speaker, and a high quality microphone. When coupled with simple waveguide test systems fabricated from commercial PVC plumbing pipe, impulse response measurement has proven to be ideal for undergraduate research projects-often of publishable quality-or for advanced laboratory experiments. The technique provides important learning objectives for science or engineering students in areas such as interfacing and computer control of experiments; analog-to-digital conversion and sampling; time and frequency analysis using Fourier transforms; signal processing; and insight into a variety of current research areas such as acoustic bandgap materials, acoustic metamaterials, and fast and slow wave manipulation. © 2012 Acoustical Society of America

Can Anomalous Amplification be Attained without Postselection?

PubMed

Martínez-Rincón, Julián; Liu, Wei-Tao; Viza, Gerardo I; Howell, John C

2016-03-11

We present a parameter estimation technique based on performing joint measurements of a weak interaction away from the weak-value-amplification approximation. Two detectors are used to collect full statistics of the correlations between two weakly entangled degrees of freedom. Without discarding of data, the protocol resembles the anomalous amplification of an imaginary-weak-value-like response. The amplification is induced in the difference signal of both detectors allowing robustness to different sources of technical noise, and offering in addition the advantages of balanced signals for precision metrology. All of the Fisher information about the parameter of interest is collected. A tunable phase controls the strength of the amplification response. We experimentally demonstrate the proposed technique by measuring polarization rotations in a linearly polarized laser pulse. We show that in the presence of technical noise the effective sensitivity and precision of a split detector is increased when compared to a conventional continuous-wave balanced detection technique.
Can Anomalous Amplification be Attained without Postselection?

NASA Astrophysics Data System (ADS)

Martínez-Rincón, Julián; Liu, Wei-Tao; Viza, Gerardo I.; Howell, John C.

2016-03-01

We present a parameter estimation technique based on performing joint measurements of a weak interaction away from the weak-value-amplification approximation. Two detectors are used to collect full statistics of the correlations between two weakly entangled degrees of freedom. Without discarding of data, the protocol resembles the anomalous amplification of an imaginary-weak-value-like response. The amplification is induced in the difference signal of both detectors allowing robustness to different sources of technical noise, and offering in addition the advantages of balanced signals for precision metrology. All of the Fisher information about the parameter of interest is collected. A tunable phase controls the strength of the amplification response. We experimentally demonstrate the proposed technique by measuring polarization rotations in a linearly polarized laser pulse. We show that in the presence of technical noise the effective sensitivity and precision of a split detector is increased when compared to a conventional continuous-wave balanced detection technique.
Techniques for integrating ‐omics data

PubMed Central

Akula, Siva Prasad; Miriyala, Raghava Naidu; Thota, Hanuman; Rao, Allam Appa; Gedela, Srinubabu

2009-01-01

The challenge for -omics research is to tackle the problem of fragmentation of knowledge by integrating several sources of heterogeneous information into a coherent entity. It is widely recognized that successful data integration is one of the keys to improve productivity for stored data. Through proper data integration tools and algorithms, researchers may correlate relationships that enable them to make better and faster decisions. The need for data integration is essential for present ‐omics community, because ‐omics data is currently spread world wide in wide variety of formats. These formats can be integrated and migrated across platforms through different techniques and one of the important techniques often used is XML. XML is used to provide a document markup language that is easier to learn, retrieve, store and transmit. It is semantically richer than HTML. Here, we describe bio warehousing, database federation, controlled vocabularies and highlighting the XML application to store, migrate and validate -omics data. PMID:19255651
Techniques for integrating -omics data.

PubMed

Akula, Siva Prasad; Miriyala, Raghava Naidu; Thota, Hanuman; Rao, Allam Appa; Gedela, Srinubabu

2009-01-01

The challenge for -omics research is to tackle the problem of fragmentation of knowledge by integrating several sources of heterogeneous information into a coherent entity. It is widely recognized that successful data integration is one of the keys to improve productivity for stored data. Through proper data integration tools and algorithms, researchers may correlate relationships that enable them to make better and faster decisions. The need for data integration is essential for present -omics community, because -omics data is currently spread world wide in wide variety of formats. These formats can be integrated and migrated across platforms through different techniques and one of the important techniques often used is XML. XML is used to provide a document markup language that is easier to learn, retrieve, store and transmit. It is semantically richer than HTML. Here, we describe bio warehousing, database federation, controlled vocabularies and highlighting the XML application to store, migrate and validate -omics data.
A systematic review of current and emergent manipulator control approaches

NASA Astrophysics Data System (ADS)

Ajwad, Syed Ali; Iqbal, Jamshed; Ullah, Muhammad Imran; Mehmood, Adeel

2015-06-01

Pressing demands of productivity and accuracy in today's robotic applications have highlighted an urge to replace classical control strategies with their modern control counterparts. This recent trend is further justified by the fact that the robotic manipulators have complex nonlinear dynamic structure with uncertain parameters. Highlighting the authors' research achievements in the domain of manipulator design and control, this paper presents a systematic and comprehensive review of the state-of-the-art control techniques that find enormous potential in controlling manipulators to execute cuttingedge applications. In particular, three kinds of strategies, i.e., intelligent proportional-integral-derivative (PID) scheme, robust control and adaptation based approaches, are reviewed. Future trend in the subject area is commented. Open-source simulators to facilitate controller design are also tabulated. With a comprehensive list of references, it is anticipated that the review will act as a firsthand reference for researchers, engineers and industrialinterns to realize the control laws for multi-degree of freedom (DOF) manipulators.
Efficient RF energy harvesting by using a fractal structured rectenna system

NASA Astrophysics Data System (ADS)

Oh, Sechang; Ramasamy, Mouli; Varadan, Vijay K.

2014-04-01

A rectenna system delivers, collects, and converts RF energy into direct current to power the electronic devices or recharge batteries. It consists of an antenna for receiving RF power, an input filter for processing energy and impedance matching, a rectifier, an output filter, and a load resistor. However, the conventional rectenna systems have drawback in terms of power generation, as the single resonant frequency of an antenna can generate only low power compared to multiple resonant frequencies. A multi band rectenna system is an optimal solution to generate more power. This paper proposes the design of a novel rectenna system, which involves developing a multi band rectenna with a fractal structured antenna to facilitate an increase in energy harvesting from various sources like Wi-Fi, TV signals, mobile networks and other ambient sources, eliminating the limitation of a single band technique. The usage of fractal antennas effects certain prominent advantages in terms of size and multiple resonances. Even though, a fractal antenna incorporates multiple resonances, controlling the resonant frequencies is an important aspect to generate power from the various desired RF sources. Hence, this paper also describes the design parameters of the fractal antenna and the methods to control the multi band frequency.
Intense, carrier frequency and bandwidth tunable quasi single-cycle pulses from an organic emitter covering the Terahertz frequency gap

PubMed Central

Vicario, C.; Monoszlai, B.; Jazbinsek, M.; Lee, S. -H.; Kwon, O. -P.; Hauri, C. P.

2015-01-01

In Terahertz (THz) science, one of the long-standing challenges has been the formation of spectrally dense, single-cycle pulses with tunable duration and spectrum across the frequency range of 0.1–15 THz (THz gap). This frequency band, lying between the electronically and optically accessible spectra hosts important molecular fingerprints and collective modes which cannot be fully controlled by present strong-field THz sources. We present a method that provides powerful single-cycle THz pulses in the THz gap with a stable absolute phase whose duration can be continuously selected between 68 fs and 1100 fs. The loss-free and chirp-free technique is based on optical rectification of a wavelength-tunable pump pulse in the organic emitter HMQ-TMS that allows for tuning of the spectral bandwidth from 1 to more than 7 octaves over the entire THz gap. The presented source tunability of the temporal carrier frequency and spectrum expands the scope of spectrally dense THz sources to time-resolved nonlinear THz spectroscopy in the entire THz gap. This opens new opportunities towards ultrafast coherent control over matter and light. PMID:26400005
Lock Acquisition and Sensitivity Analysis of Advanced LIGO Interferometers

NASA Astrophysics Data System (ADS)

Martynov, Denis

Laser interferometer gravitational wave observatory (LIGO) consists of two complex large-scale laser interferometers designed for direct detection of gravitational waves from distant astrophysical sources in the frequency range 10Hz - 5kHz. Direct detection of space-time ripples will support Einstein's general theory of relativity and provide invaluable information and new insight into physics of the Universe. The initial phase of LIGO started in 2002, and since then data was collected during the six science runs. Instrument sensitivity improved from run to run due to the effort of commissioning team. Initial LIGO has reached designed sensitivity during the last science run, which ended in October 2010. In parallel with commissioning and data analysis with the initial detector, LIGO group worked on research and development of the next generation of detectors. Major instrument upgrade from initial to advanced LIGO started in 2010 and lasted until 2014. This thesis describes results of commissioning work done at the LIGO Livingston site from 2013 until 2015 in parallel with and after the installation of the instrument. This thesis also discusses new techniques and tools developed at the 40m prototype including adaptive filtering, estimation of quantization noise in digital filters and design of isolation kits for ground seismometers. The first part of this thesis is devoted to the description of methods for bringing the interferometer into linear regime when collection of data becomes possible. States of longitudinal and angular controls of interferometer degrees of freedom during lock acquisition process and in low noise configuration are discussed in details. Once interferometer is locked and transitioned to low noise regime, instrument produces astrophysics data that should be calibrated to units of meters or strain. The second part of this thesis describes online calibration technique set up in both observatories to monitor the quality of the collected data in real time. Sensitivity analysis was done to understand and eliminate noise sources of the instrument. The coupling of noise sources to gravitational wave channel can be reduced if robust feedforward and optimal feedback control loops are implemented. Static and adaptive feedforward noise cancellation techniques applied to Advanced LIGO interferometers and tested at the 40m prototype are described in the last part of this thesis. Applications of optimal time domain feedback control techniques and estimators to aLIGO control loops are also discussed. Commissioning work is still ongoing at the sites. First science run of advanced LIGO is planned for September 2015 and will last for 3-4 months. This run will be followed by a set of small instrument upgrades that will be installed on a time scale of few months. Second science run will start in spring 2016 and last for about six months. Since current sensitivity of advanced LIGO is already more than a factor of 3 higher compared to initial detectors and keeps improving on a monthly basis, the upcoming science runs have a good chance for the first direct detection of gravitational waves.
Source Memory Rehabilitation: A Review Toward Recommendations for Setting Up a Strategy Training Aimed at the "What, Where, and When" of Episodic Retrieval.

PubMed

El Haj, Mohamad; Kessels, Roy P C; Allain, Philippe

2016-01-01

Source memory is a core component of episodic recall as it allows for the reconstruction of contextual details characterizing the acquisition of episodic events. Unlike episodic memory, little is known about source memory rehabilitation. Our review addresses this issue by emphasizing several strategies as useful tools in source memory rehabilitation programs. Four main strategies are likely to improve source recall in amnesic patients-namely, (a) contextual cueing, (b) unitization, (c) errorless learning, and (d) executive function programs. The rationale behind our suggestion is that: (a) reinstating contextual cues during retrieval can serve as retrieval cues and enhance source memory; (b) unitization as an encoding process allows for the integration of several pieces of contextual information into a new single entity; (c) errorless learning may prevent patients from making errors during source learning; and (d) as source memory deteriorations have been classically attributed to executive dysfunction, the rehabilitation of the latter ability is likely to maintain the former ability. Besides these four strategies, our review suggests several additional rehabilitation techniques such as the vanishing cues and spaced retrieval methods. Another additional strategy is the use of electronic devices. By gathering these strategies, our review provides a helpful guideline for clinicians dealing with source memory impairments. Our review further highlights the lack of randomized and controlled studies in the field of source memory rehabilitation.
Quantitative phase imaging of living cells with a swept laser source

NASA Astrophysics Data System (ADS)

Chen, Shichao; Zhu, Yizheng

2016-03-01

Digital holographic phase microscopy is a well-established quantitative phase imaging technique. However, interference artifacts from inside the system, typically induced by elements whose optical thickness are within the source coherence length, limit the imaging quality as well as sensitivity. In this paper, a swept laser source based technique is presented. Spectra acquired at a number of wavelengths, after Fourier Transform, can be used to identify the sources of the interference artifacts. With proper tuning of the optical pathlength difference between sample and reference arms, it is possible to avoid these artifacts and achieve sensitivity below 0.3nm. Performance of the proposed technique is examined in live cell imaging.
Radical Sources in the Uintah Basin during 2013 Winter Ozone Episodes

NASA Astrophysics Data System (ADS)

Roberts, J. M.; Yuan, B.; Veres, P. R.; Warneke, C.; De Gouw, J. A.; Geiger, F.; Brown, S. S.; Edwards, P. M.; Wild, R.; Min, K.; Bates, T. S.; Quinn, P.; Banta, R. M.; Zamora, R. J.; McLaren, R.; Young, C.; Kercher, J. P.; Thornton, J. A.; Williams, E. J.

2013-12-01

Winter time O3 in excess of the NAAQS, 75 ppbv, has been observed in several geographic basins in Wyoming and Utah that are heavily impacted by emissions from oil and gas operations. The timing and circumstances of these high O3 events imply that radical sources such as HONO, HCHO, and perhaps ClNO2 are significant relative to the traditional O3-photolysis channel. Here we present data from the 2013 Uintah Basin Winter Ozone Study (UBWOS) that show that HONO and HCHO were the major sources of radicals during O3 episodes. This result stands in contrast to the results obtained in more typical urban atmospheres, such as the CalNEx 2010 measurements in Pasadena, where O3 photolysis was found to be the major radical source. The precise contribution of each radical source during UBWOS 2013 awaits further work on the fluxes to and from snow surfaces, and verification of HONO measurement techniques. Such a coupling of radical and NOx sources complicates the traditional NOx vs.VOC paradigm in which one or the other quantity determines the best O3 control strategy. This amplifies the need for a quantitative understanding of NOx to HONO conversion mechanisms.
Use of FEC coding to improve statistical multiplexing performance for video transport over ATM networks

NASA Astrophysics Data System (ADS)

Kurceren, Ragip; Modestino, James W.

1998-12-01

The use of forward error-control (FEC) coding, possibly in conjunction with ARQ techniques, has emerged as a promising approach for video transport over ATM networks for cell-loss recovery and/or bit error correction, such as might be required for wireless links. Although FEC provides cell-loss recovery capabilities it also introduces transmission overhead which can possibly cause additional cell losses. A methodology is described to maximize the number of video sources multiplexed at a given quality of service (QoS), measured in terms of decoded cell loss probability, using interlaced FEC codes. The transport channel is modelled as a block interference channel (BIC) and the multiplexer as single server, deterministic service, finite buffer supporting N users. Based upon an information-theoretic characterization of the BIC and large deviation bounds on the buffer overflow probability, the described methodology provides theoretically achievable upper limits on the number of sources multiplexed. Performance of specific coding techniques using interlaced nonbinary Reed-Solomon (RS) codes and binary rate-compatible punctured convolutional (RCPC) codes is illustrated.
Environmental Electrokinetics for a sustainable subsurface.

PubMed

Lima, A T; Hofmann, A; Reynolds, D; Ptacek, C J; Van Cappellen, P; Ottosen, L M; Pamukcu, S; Alshawabekh, A; O'Carroll, D M; Riis, C; Cox, E; Gent, D B; Landis, R; Wang, J; Chowdhury, A I A; Secord, E L; Sanchez-Hachair, A

2017-08-01

Soil and groundwater are key components in the sustainable management of the subsurface environment. Source contamination is one of its main threats and is commonly addressed using established remediation techniques such as in-situ chemical oxidation (ISCO), in-situ chemical reduction (ISCR; most notably using zero-valent iron [ZVI]), enhanced in-situ bioremediation (EISB), phytoremediation, soil-washing, pump-and-treat, soil vapour extraction (SVE), thermal treatment, and excavation and disposal. Decades of field applications have shown that these techniques can successfully treat or control contaminants in higher permeability subsurface materials such as sands, but achieve only limited success at sites where low permeability soils, such as silts and clays, prevail. Electrokinetics (EK), a soil remediation technique mostly recognized in in-situ treatment of low permeability soils, has, for the last decade, been combined with more conventional techniques and can significantly enhance the performance of several of these remediation technologies, including ISCO, ISCR, EISB and phytoremediation. Herein, we discuss the use of emerging EK techniques in tandem with conventional remediation techniques, to achieve improved remediation performance. Furthermore, we highlight new EK applications that may come to play a role in the sustainable treatment of the contaminated subsurface. Copyright © 2017 Elsevier Ltd. All rights reserved.
Formaldehyde concentrations in household air of asthma patients determined using colorimetric detector tubes

PubMed Central

Dannemiller, Karen C.; Murphy, Johnna S.; Dixon, Sherry L.; Pennell, Kelly G.; Suuberg, Eric M.; Jacobs, David E.; Sandel, Megan

2013-01-01

Formaldehyde is a colorless, pungent gas commonly found in homes that is a respiratory irritant, sensitizer, carcinogen and asthma trigger. Typical household sources include plywood and particleboard, cleaners, cosmetics, pesticides, and others. Development of a fast and simple measurement technique could facilitate continued research on this important chemical. The goal of this research is to apply an inexpensive short-term measurement method to find correlations between formaldehyde sources and concentration, and formaldehyde concentration and asthma control. Formaldehyde was measured using 30-minute grab samples in length-of-stain detector tubes in homes (n=70) of asthmatics in the Boston, MA area. Clinical status and potential formaldehyde sources were determined. The geometric mean formaldehyde level was 35.1 ppb and ranged from 5–132 ppb. Based on one-way ANOVA, t-tests, and linear regression, predictors of log-transformed formaldehyde concentration included absolute humidity, season, and the presence of decorative laminates, fiberglass, or permanent press fabrics (p<0.05), as well as temperature and household cleaner use (p<0.10). The geometric mean formaldehyde concentration was 57% higher in homes of children with very poorly controlled asthma compared to homes of other asthmatic children (p=0.078). This study provides a simple method for measuring household formaldehyde and suggests that exposure is related to poorly controlled asthma. PMID:23278296
Spatio-temporal patterns and source apportionment of pollution in Qiantang River (China) using neural-based modeling and multivariate statistical techniques

NASA Astrophysics Data System (ADS)

Su, Shiliang; Zhi, Junjun; Lou, Liping; Huang, Fang; Chen, Xia; Wu, Jiaping

Characterizing the spatio-temporal patterns and apportioning the pollution sources of water bodies are important for the management and protection of water resources. The main objective of this study is to describe the dynamics of water quality and provide references for improving river pollution control practices. Comprehensive application of neural-based modeling and different multivariate methods was used to evaluate the spatio-temporal patterns and source apportionment of pollution in Qiantang River, China. Measurement data were obtained and pretreated for 13 variables from 41 monitoring sites for the period of 2001-2004. A self-organizing map classified the 41 monitoring sites into three groups (Group A, B and C), representing different pollution characteristics. Four significant parameters (dissolved oxygen, biochemical oxygen demand, total phosphorus and total lead) were identified by discriminant analysis for distinguishing variations of different years, with about 80% correct assignment for temporal variation. Rotated principal component analysis (PCA) identified four potential pollution sources for Group A (domestic sewage and agricultural pollution, industrial wastewater pollution, mineral weathering, vehicle exhaust and sand mining), five for Group B (heavy metal pollution, agricultural runoff, vehicle exhaust and sand mining, mineral weathering, chemical plants discharge) and another five for Group C (vehicle exhaust and sand mining, chemical plants discharge, soil weathering, biochemical pollution, mineral weathering). The identified potential pollution sources explained 75.6% of the total variances for Group A, 75.0% for Group B and 80.0% for Group C, respectively. Receptor-based source apportionment was applied to further estimate source contributions for each pollution variable in the three groups, which facilitated and supported the PCA results. These results could assist managers to develop optimal strategies and determine priorities for river pollution control and effective water resources management.
A new storage-ring light source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, Alex

2015-06-01

A recently proposed technique in storage ring accelerators is applied to provide potential high-power sources of photon radiation. The technique is based on the steady-state microbunching (SSMB) mechanism. As examples of this application, one may consider a high-power DUV photon source for research in atomic and molecular physics or a high-power EUV radiation source for industrial lithography. A less challenging proof-of-principle test to produce IR radiation using an existing storage ring is also considered.
The optimal modified variational iteration method for the Lane-Emden equations with Neumann and Robin boundary conditions

NASA Astrophysics Data System (ADS)

Singh, Randhir; Das, Nilima; Kumar, Jitendra

2017-06-01

An effective analytical technique is proposed for the solution of the Lane-Emden equations. The proposed technique is based on the variational iteration method (VIM) and the convergence control parameter h . In order to avoid solving a sequence of nonlinear algebraic or complicated integrals for the derivation of unknown constant, the boundary conditions are used before designing the recursive scheme for solution. The series solutions are found which converges rapidly to the exact solution. Convergence analysis and error bounds are discussed. Accuracy, applicability of the method is examined by solving three singular problems: i) nonlinear Poisson-Boltzmann equation, ii) distribution of heat sources in the human head, iii) second-kind Lane-Emden equation.
Inhomogeneities and segregation behavior in strontium—barium niobate fibers grown by laser-heated pedestal growth technique. Part II

NASA Astrophysics Data System (ADS)

Erdei, S.; Galambos, L.; Tanaka, I.; Hesselink, L.; Cross, L. E.; Feigelson, R. S.; Ainger, F. W.; Kojima, H.

1996-10-01

Inhomogeneities in Ce-doped and undoped fibers grown by laser-heated pedestal growth (LHPG) along the c- or a- axis were investigated by two-dimensional scanning electron microprobe analysis (SEPMA). SEPMA data indicated that these cores are primarily connected with the source rod compositions utilized and the convection characteristics of the LHPG technique. Ba enrichment and Sr decrease were primarily detected in the cores and qualitatively described in terms of the composition-control mechanism of LHPG, the complex-segregation and a modified Burton—Prim—Slichter (BPS) equation. Certain aspects of defect structure as a complex congruency related phenomenon are also discussed in the paper giving a more complete interpretation of the origin of cores in SBN fibers.
A study of poultry processing plant noise control techniques

NASA Technical Reports Server (NTRS)

Wyvill, J. C.; Morrison, W. G., Jr.

1981-01-01

A number of techniques can be used to reduce noise in poultry processing plants. In general, covering the ceiling with a noise-absorbing medium is a practical first step. Once the reflected noise levels are abated, treatment of specific identifiable noise courses can take place. The development, flammability, and mechanical properties of acoustic panels to be vertically suspended from the ceiling are discussed as well as the covers need to comply with USDA cleanability requirements. The isolation of drive motors and pumps from large expansive areas, the muffling of pneumatic devices, and the insulation of ice chutes are methods of source quieting. Proper maintenance of machinery and vibration monitoring are also needed to reduce hearing damage risk and to improve worker productivity and employee/supervisor relations.
Technique of after-loading interstitial implants.

PubMed

Syed, A M; Feder, B H

1977-01-01

Interstitial implants are either removable or permanent (and occasionally a combination of both). Permanent implants are generally utilized where tumors are not accessible enough to permit easy removal of sources or where accurate source distribution is less critical. They are useful for cancers of the lung, pancreas, prostate, bladder, lymph nodes, etc. Radon and gold-198 have been largely replaced by iodine-125. Our major interests are in the removable after-loading iridium-192 implant techniques. Template (steel guide) and non-template (plastic tube) techniques are utilized. Templates are preferred where the tumor volume can only be approached from one side and where accurate positioning of sources would otherwise be difficult. They are useful for cancers of the cervix, vagina, urethra, and rectum. Non-template (plastic tube) techniques are preferred where the tumor volume can be approached from at least two sides and where templates are either not feasible or not essential for accurate positioning of sources. The single needle non-template approach is useful for cancers of lip, nodes, and breast (plastic button) and for cancers of the oral cavity and oropharynx (gold button). The paired needle non-template approach is useful for cancers of the gum, retromolar trigone, and base of tongue (loop technique) and for cancers of the palate (arch technique). Procedures for each technique are described in detail.

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