Color quality management in advanced flat panel display engines

Science.gov (United States)

Lebowsky, Fritz; Neugebauer, Charles F.; Marnatti, David M.

2003-01-01

During recent years color reproduction systems for consumer needs have experienced various difficulties. In particular, flat panels and printers could not reach a satisfactory color match. The RGB image stored on an Internet server of a retailer did not show the desired colors on a consumer display device or printer device. STMicroelectronics addresses this important color reproduction issue inside their advanced display engines using novel algorithms targeted for low cost consumer flat panels. Using a new and genuine RGB color space transformation, which combines a gamma correction Look-Up-Table, tetrahedrization, and linear interpolation, we satisfy market demands.

Laser illuminated flat panel display

Energy Technology Data Exchange (ETDEWEB)

Veligdan, J.T.

1995-12-31

A 10 inch laser illuminated flat panel Planar Optic Display (POD) screen has been constructed and tested. This POD screen technology is an entirely new concept in display technology. Although the initial display is flat and made of glass, this technology lends itself to applications where a plastic display might be wrapped around the viewer. The display screen is comprised of hundreds of planar optical waveguides where each glass waveguide represents a vertical line of resolution. A black cladding layer, having a lower index of refraction, is placed between each waveguide layer. Since the cladding makes the screen surface black, the contrast is high. The prototype display is 9 inches wide by 5 inches high and approximately I inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

Flat panel planar optic display

Energy Technology Data Exchange (ETDEWEB)

Veligdan, J.T. [Brookhaven National Lab., Upton, NY (United States). Dept. of Advanced Technology

1994-11-01

A prototype 10 inch flat panel Planar Optic Display, (POD), screen has been constructed and tested. This display screen is comprised of hundreds of planar optic class sheets bonded together with a cladding layer between each sheet where each glass sheet represents a vertical line of resolution. The display is 9 inches wide by 5 inches high and approximately 1 inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

Coupled Electro-Magneto-Mechanical-Acoustic Analysis Method Developed by Using 2D Finite Element Method for Flat Panel Speaker Driven by Magnetostrictive-Material-Based Actuator

Science.gov (United States)

Yoo, Byungjin; Hirata, Katsuhiro; Oonishi, Atsurou

In this study, a coupled analysis method for flat panel speakers driven by giant magnetostrictive material (GMM) based actuator was developed. The sound field produced by a flat panel speaker that is driven by a GMM actuator depends on the vibration of the flat panel, this vibration is a result of magnetostriction property of the GMM. In this case, to predict the sound pressure level (SPL) in the audio-frequency range, it is necessary to take into account not only the magnetostriction property of the GMM but also the effect of eddy current and the vibration characteristics of the actuator and the flat panel. In this paper, a coupled electromagnetic-structural-acoustic analysis method is presented; this method was developed by using the finite element method (FEM). This analysis method is used to predict the performance of a flat panel speaker in the audio-frequency range. The validity of the analysis method is verified by comparing with the measurement results of a prototype speaker.

Supersonic Panel Flutter Test Results for Flat Fiber-Glass Sandwich Panels with Foamed Cores

Science.gov (United States)

Tuovila, W. J.; Presnell, John G., Jr.

1961-01-01

Flutter tests have been made on flat panels having a 1/4 inch-thick plastic-foam core covered with thin fiber-glass laminates. The testing was done in the Langley Unitary Plan wind tunnel at Mach numbers from 1.76 t o 2.87. The flutter boundary for these panels was found to be near the flutter boundary of thin metal panels when compared on the basis of an equivalent panel stiffness. The results also demonstrated that the depth of the cavity behind the panel has a pronounced influence on flutter. Changing the cavity depth from 1 1/2 inches to 1/2 inch reduced the dynamic pressure at start of flutter by 40 percent. No flutter was obtained when the spacers on the back of the panel were against the bottom of the cavity.

Visual and ocular effects from the use of flat-panel displays

Directory of Open Access Journals (Sweden)

Esteban Porcar

2016-06-01

Full Text Available AIM: To evaluate the prevalence of eye symptoms in a non-presbyopic population of video display unit (VDU users with flat-panel displays. METHODS: One hundred and sixteen VDU users with flat-panel display from an urban population participated in the study; their ages ranging from 20 to 34y. There were 60 females and 56 males. An eye examination to rule out the presence of significant uncorrected refractive errors, general binocular dysfunctions and eye conditions was carried out. In order to determine and quantify the type and nature of eye symptoms, participants were asked to answer written questionnaire and the results were grouped by gender, age and number of hours a day spent using a VDU. RESULTS: Seventy-two percent of participants reported eye symptoms related to VDU use. Eye symptoms from moderate-to-severe were found in 23% of participants. The main symptom was moderate-to-severe tired eyes (14%; followed by sensitivity to bright lights (12%, blurred vision at far distances (10%, eyestrain or dry eye or irritated or burning eyes (9%, difficulty in refocusing from one distance to another or headache (8% and blurred vision at near or intermediate distances (<4%. Eye symptoms were greater among females (P=0.005 and increased with VDU use, markedly above 6h spent using a VDU in a typical day (P=0.01. CONCLUSION: Significant eye symptoms relate to VDU use often occur and should not be underestimated. The increasing use of electronic devices with flat-panel display should prompt users to take appropriate measures to prevent or to relieve the eye symptoms arising from their use.

High-performance flat-panel solar thermoelectric generators with high thermal concentration

Science.gov (United States)

Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J. Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

2011-07-01

The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m-2) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity.

High-performance flat-panel solar thermoelectric generators with high thermal concentration.

Science.gov (United States)

Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

2011-05-01

The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m(-2)) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity. © 2011 Macmillan Publishers Limited. All rights reserved

Indirect flat-panel detector with avalanche gain: Fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager)

International Nuclear Information System (INIS)

Zhao Wei; Li Dan; Reznik, Alla; Lui, B.J.M.; Hunt, D.C.; Rowlands, J.A.; Ohkawa, Yuji; Tanioka, Kenkichi

2005-01-01

An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed detector SHARP-AMFPI (scintillator HARP active matrix flat panel imager). The advantage of the SHARP-AMFPI is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoid pixel saturation. The purpose of this paper is to investigate the important design considerations for SHARP-AMFPI such as avalanche gain, which depends on both the thickness d Se and the applied electric field E Se of the HARP layer. To determine the optimal design parameter and operational conditions for HARP, we measured the E Se dependence of both avalanche gain and optical quantum efficiency of an 8 μm HARP layer. The results were used in a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and nonavalanche modes as a function of E Se : (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; (4) gain nonuniformity resulting from thickness nonuniformity; and (5) effects of direct x-ray interaction in HARP. Our results showed that a HARP layer thickness of 8 μm can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy

Improvement of illumination uniformity for LED flat panel light by using micro-secondary lens array.

Science.gov (United States)

Lee, Hsiao-Wen; Lin, Bor-Shyh

2012-11-05

LED flat panel light is an innovative lighting product in recent years. However, current flat panel light products still contain some drawbacks, such as narrow lighting areas and hot spots. In this study, a micro-secondary lens array technique was proposed and applied for the design of the light guide surface to improve the illumination uniformity. By using the micro-secondary lens array, the candela distribution of the LED flat panel light can be adjusted to similar to batwing distribution to improve the illumination uniformity. The experimental results show that the enhancement of the floor illumination uniformity is about 61%, and that of the wall illumination uniformity is about 20.5%.

Measurement of effective detective quantum efficiency for a photon counting scanning mammography system and comparison with two flat panel full-field digital mammography systems

Science.gov (United States)

Wood, Tim J.; Moore, Craig S.; Saunderson, John R.; Beavis, Andrew W.

2018-01-01

Effective detective quantum efficiency (eDQE) describes the resolution and noise properties of an imaging system along with scatter and primary transmission, all measured under clinically appropriate conditions. Effective dose efficiency (eDE) is the eDQE normalised to mean glandular dose and has been proposed as a useful metric for the optimisation of clinical imaging systems. The aim of this study was to develop a methodology for measuring eDQE and eDE on a Philips microdose mammography (MDM) L30 photon counting scanning system, and to compare performance with two conventional flat panel systems. A custom made lead-blocker was manufactured to enable the accurate determination of dose measurements, and modulation transfer functions were determined free-in-air at heights of 2, 4 and 6 cm above the breast support platform. eDQE were calculated for a Philips MDM L30, Hologic Dimensions and Siemens Inspiration digital mammography system for 2, 4 and 6 cm thick poly(methyl methacrylate) (PMMA). The beam qualities (target/filter and kilovoltage) assessed were those selected by the automatic exposure control, and anti-scatter grids were used where available. Measurements of eDQE demonstrate significant differences in performance between the slit- and scan-directions for the photon counting imaging system. MTF has been shown to be the limiting factor in the scan-direction, which results in a rapid fall in eDQE at mid-to-high spatial frequencies. A comparison with two flat panel mammography systems demonstrates that this may limit image quality for small details, such as micro-calcifications, which correlates with a more conventional image quality assessment with the CDMAM phantom. eDE has shown the scanning photon counting system offers superior performance for low spatial frequencies, which will be important for the detection of large low contrast masses. Both eDQE and eDE are proposed as useful metrics that should enable optimisation of the Philips MDM L30.

Flat-panel electronic displays: a triumph of physics, chemistry and engineering.

Science.gov (United States)

Hilsum, Cyril

2010-03-13

This paper describes the history and science behind the development of modern flat-panel displays, and assesses future trends. Electronic displays are an important feature of modern life. For many years the cathode ray tube, an engineering marvel, was universal, but its shape was cumbersome and its operating voltage too high. The need for a flat-panel display, working at a low voltage, became imperative, and much research has been applied to this need. Any versatile flat-panel display will exploit an electro-optical effect, a transparent conductor and an addressing system to deliver data locally. The first need is to convert an electrical signal into a visible change. Two methods are available, the first giving emission of light, the second modulating ambient illumination. The most useful light-emitting media are semiconductors, historically exploiting III-V or II-VI compounds, but more recently organic or polymer semiconductors. Another possible effect uses gas plasma discharges. The modulating, or subtractive, effects that have been studied include liquid crystals, electrophoresis, electrowetting and electrochromism. A transparent conductor makes it possible to apply a voltage to an extended area while observing the results. The design is a compromise, since the free electrons that carry current also absorb light. The first materials used were metals, but some semiconductors, when heavily doped, give a better balance, with high transmission for a low resistance. Delivering data unambiguously to a million or so picture elements across the display area is no easy task. The preferred solution is an amorphous silicon thin-film transistor deposited at each cross-point in an X-Y matrix. Success in these endeavours has led to many applications for flat-panel displays, including television, flexible displays, electronic paper, electronic books and advertising signs.

Diffractive flat panel solar concentrators of a novel design

NARCIS (Netherlands)

De Jong, T.M.; de Boer, D.K.G.; Bastiaansen, C.W.M.

2016-01-01

A novel design for a flat panel solar concentrator is presented which is based on a light guide with a grating applied on top that diffracts light into total internal reflection. By combining geometrical and diffractive optics the geometrical concentration ratio is optimized according to the

Tracking brachytherapy sources using emission imaging with one flat panel detector

International Nuclear Information System (INIS)

Song Haijun; Bowsher, James; Das, Shiva; Yin Fangfang

2009-01-01

This work proposes to use the radiation from brachytherapy sources to track their dwell positions in three-dimensional (3D) space. The prototype device uses a single flat panel detector and a BB tray. The BBs are arranged in a defined pattern. The shadow of the BBs on the flat panel is analyzed to derive the 3D coordinates of the illumination source, i.e., the dwell position of the brachytherapy source. A kilovoltage x-ray source located 3.3 m away was used to align the center BB with the center pixel on the flat panel detector. For a test plan of 11 dwell positions, with an Ir-192 high dose rate unit, one projection was taken for each dwell point, and locations of the BB shadows were manually identified on the projection images. The 3D coordinates for the 11 dwell positions were reconstructed based on two BBs. The distances between dwell points were compared with the expected values. The average difference was 0.07 cm with a standard deviation of 0.15 cm. With automated BB shadow recognition in the future, this technique possesses the potential of tracking the 3D trajectory and the dwell times of a brachytherapy source in real time, enabling real time source position verification.

A semiempirical linear model of indirect, flat-panel x-ray detectors

Energy Technology Data Exchange (ETDEWEB)

Huang, Shih-Ying; Yang Kai; Abbey, Craig K.; Boone, John M. [Department of Biomedical Engineering, University of California, Davis, California, One Shields Avenue, Davis, California 95616 (United States) and Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 0505, Sacramento, California 95817 (United States); Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 0505, Sacramento, California 95817 (United States); Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 92106 (United States); Department of Biomedical Engineering, University of California, Davis, California, One Shields Avenue, Davis, California 95616 (United States) and Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 3100, Sacramento, California 95817 (United States)

2012-04-15

Purpose: It is important to understand signal and noise transfer in the indirect, flat-panel x-ray detector when developing and optimizing imaging systems. For optimization where simulating images is necessary, this study introduces a semiempirical model to simulate projection images with user-defined x-ray fluence interaction. Methods: The signal and noise transfer in the indirect, flat-panel x-ray detectors is characterized by statistics consistent with energy-integration of x-ray photons. For an incident x-ray spectrum, x-ray photons are attenuated and absorbed in the x-ray scintillator to produce light photons, which are coupled to photodiodes for signal readout. The signal mean and variance are linearly related to the energy-integrated x-ray spectrum by empirically determined factors. With the known first- and second-order statistics, images can be simulated by incorporating multipixel signal statistics and the modulation transfer function of the imaging system. To estimate the semiempirical input to this model, 500 projection images (using an indirect, flat-panel x-ray detector in the breast CT system) were acquired with 50-100 kilovolt (kV) x-ray spectra filtered with 0.1-mm tin (Sn), 0.2-mm copper (Cu), 1.5-mm aluminum (Al), or 0.05-mm silver (Ag). The signal mean and variance of each detector element and the noise power spectra (NPS) were calculated and incorporated into this model for accuracy. Additionally, the modulation transfer function of the detector system was physically measured and incorporated in the image simulation steps. For validation purposes, simulated and measured projection images of air scans were compared using 40 kV/0.1-mm Sn, 65 kV/0.2-mm Cu, 85 kV/1.5-mm Al, and 95 kV/0.05-mm Ag. Results: The linear relationship between the measured signal statistics and the energy-integrated x-ray spectrum was confirmed and incorporated into the model. The signal mean and variance factors were linearly related to kV for each filter material (r

A semiempirical linear model of indirect, flat-panel x-ray detectors

International Nuclear Information System (INIS)

Huang, Shih-Ying; Yang Kai; Abbey, Craig K.; Boone, John M.

2012-01-01

Purpose: It is important to understand signal and noise transfer in the indirect, flat-panel x-ray detector when developing and optimizing imaging systems. For optimization where simulating images is necessary, this study introduces a semiempirical model to simulate projection images with user-defined x-ray fluence interaction. Methods: The signal and noise transfer in the indirect, flat-panel x-ray detectors is characterized by statistics consistent with energy-integration of x-ray photons. For an incident x-ray spectrum, x-ray photons are attenuated and absorbed in the x-ray scintillator to produce light photons, which are coupled to photodiodes for signal readout. The signal mean and variance are linearly related to the energy-integrated x-ray spectrum by empirically determined factors. With the known first- and second-order statistics, images can be simulated by incorporating multipixel signal statistics and the modulation transfer function of the imaging system. To estimate the semiempirical input to this model, 500 projection images (using an indirect, flat-panel x-ray detector in the breast CT system) were acquired with 50-100 kilovolt (kV) x-ray spectra filtered with 0.1-mm tin (Sn), 0.2-mm copper (Cu), 1.5-mm aluminum (Al), or 0.05-mm silver (Ag). The signal mean and variance of each detector element and the noise power spectra (NPS) were calculated and incorporated into this model for accuracy. Additionally, the modulation transfer function of the detector system was physically measured and incorporated in the image simulation steps. For validation purposes, simulated and measured projection images of air scans were compared using 40 kV/0.1-mm Sn, 65 kV/0.2-mm Cu, 85 kV/1.5-mm Al, and 95 kV/0.05-mm Ag. Results: The linear relationship between the measured signal statistics and the energy-integrated x-ray spectrum was confirmed and incorporated into the model. The signal mean and variance factors were linearly related to kV for each filter material (r 2 of

A semiempirical linear model of indirect, flat-panel x-ray detectors.

Science.gov (United States)

Huang, Shih-Ying; Yang, Kai; Abbey, Craig K; Boone, John M

2012-04-01

It is important to understand signal and noise transfer in the indirect, flat-panel x-ray detector when developing and optimizing imaging systems. For optimization where simulating images is necessary, this study introduces a semiempirical model to simulate projection images with user-defined x-ray fluence interaction. The signal and noise transfer in the indirect, flat-panel x-ray detectors is characterized by statistics consistent with energy-integration of x-ray photons. For an incident x-ray spectrum, x-ray photons are attenuated and absorbed in the x-ray scintillator to produce light photons, which are coupled to photodiodes for signal readout. The signal mean and variance are linearly related to the energy-integrated x-ray spectrum by empirically determined factors. With the known first- and second-order statistics, images can be simulated by incorporating multipixel signal statistics and the modulation transfer function of the imaging system. To estimate the semiempirical input to this model, 500 projection images (using an indirect, flat-panel x-ray detector in the breast CT system) were acquired with 50-100 kilovolt (kV) x-ray spectra filtered with 0.1-mm tin (Sn), 0.2-mm copper (Cu), 1.5-mm aluminum (Al), or 0.05-mm silver (Ag). The signal mean and variance of each detector element and the noise power spectra (NPS) were calculated and incorporated into this model for accuracy. Additionally, the modulation transfer function of the detector system was physically measured and incorporated in the image simulation steps. For validation purposes, simulated and measured projection images of air scans were compared using 40 kV∕0.1-mm Sn, 65 kV∕0.2-mm Cu, 85 kV∕1.5-mm Al, and 95 kV∕0.05-mm Ag. The linear relationship between the measured signal statistics and the energy-integrated x-ray spectrum was confirmed and incorporated into the model. The signal mean and variance factors were linearly related to kV for each filter material (r(2) of signal mean to k

Development of Surfaces Optically Suitable for Flat Solar Panels

Science.gov (United States)

Desmet, D.; Jason, A.

1978-01-01

Three areas of research in the development of flat solar panels are described. (1) A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces was developed. The reflectometer has a phase locked detection system. (2) A coating composed of strongly bound copper oxide that is formed by an etching process performed on an aluminum alloy with high copper content was also developed. Because of this one step fabrication process, fabrication costs are expected to be small. (3) A literature search was conducted and conclusions on the required optical properties of flat plate solar collectors are presented.

Near-field flat focusing mirrors

Science.gov (United States)

Cheng, Yu-Chieh; Staliunas, Kestutis

2018-03-01

This article reviews recent progress towards the design of near-field flat focusing mirrors, focusing/imaging light patterns in reflection. An important feature of such flat focusing mirrors is their transverse invariance, as they do not possess any optical axis. We start with a review of the physical background to the different focusing mechanisms of near- and far-field focusing. These near-field focusing devices like flat lenses and the reviewed near-field focusing mirrors can implement planar focusing devices without any optical axis. In contrast, various types of far-field planar focusing devices, such as high-contrast gratings and metasurfaces, unavoidably break the transverse invariance due to their radially symmetrical structures. The particular realizations of near-field flat focusing mirrors including Bragg-like dielectric mirrors and dielectric subwavelength gratings are the main subjects of the review. The first flat focusing mirror was demonstrated with a chirped mirror and was shown to manage an angular dispersion for beam focusing, similar to the management of chromatic dispersion for pulse compression. Furthermore, the reviewed optimized chirped mirror demonstrated a long near-field focal length, hardly achieved by a flat lens or a planar hyperlens. Two more different configurations of dielectric subwavelength gratings that focus a light beam at normal or oblique incidence are also reviewed. We also summarize and compare focusing performance, limitations, and future perspectives between the reviewed flat focusing mirrors and other planar focusing devices including a flat lens with a negative-index material, a planar hyperlens, a high-contrast grating, and a metasurface.

Analyzing panel acoustic contributions toward the sound field inside the passenger compartment of a full-size automobile.

Science.gov (United States)

Wu, Sean F; Moondra, Manmohan; Beniwal, Ravi

2015-04-01

The Helmholtz equation least squares (HELS)-based nearfield acoustical holography (NAH) is utilized to analyze panel acoustic contributions toward the acoustic field inside the interior region of an automobile. Specifically, the acoustic power flows from individual panels are reconstructed, and relative contributions to sound pressure level and spectrum at any point of interest are calculated. Results demonstrate that by correlating the acoustic power flows from individual panels to the field acoustic pressure, one can correctly locate the panel allowing the most acoustic energy transmission into the vehicle interior. The panel on which the surface acoustic pressure amplitude is the highest should not be used as indicative of the panel responsible for the sound field in the vehicle passenger compartment. Another significant advantage of this HELS-based NAH is that measurements of the input data only need to be taken once by using a conformal array of microphones in the near field, and ranking of panel acoustic contributions to any field point can be readily performed. The transfer functions between individual panels of any vibrating structure to the acoustic pressure anywhere in space are calculated not measured, thus significantly reducing the time and effort involved in panel acoustic contributions analyses.

Diffractive flat panel solar concentrators of a novel design.

Science.gov (United States)

de Jong, Ties M; de Boer, Dick K G; Bastiaansen, Cees W M

2016-07-11

A novel design for a flat panel solar concentrator is presented which is based on a light guide with a grating applied on top that diffracts light into total internal reflection. By combining geometrical and diffractive optics the geometrical concentration ratio is optimized according to the principles of nonimaging optics, while the thickness of the device is minimized due to the use of total internal reflection.

Peer review panel summary report for technical determination of mixed waste incineration off-gas systems for Rocky Flats

International Nuclear Information System (INIS)

1992-01-01

A Peer Review Panel was convened on September 15-17, 1992 in Boulder, Co. The members of this panel included representatives from DOE, EPA, and DOE contractors along with invited experts in the fields of air pollution control and waste incineration. The primary purpose of this review panel was to make a technical determination of a hold, test and release off gas capture system should be implemented in the proposed RF Pland mixed waste incineration system; or if a state of the art continuous air pollution control and monitoring system should be utilized as the sole off-gas control system. All of the evaluations by the panel were based upon the use of the fluidized bed unit proposed by Rocky Flats and cannot be generalized to other systems

Flat panel planar optic display. Revision 4/95

Energy Technology Data Exchange (ETDEWEB)

Veligdan, J.T.

1995-05-01

A prototype 10 inch flat panel Planar Optic display, (POD), screen has been constructed and tested. This display screen is comprised of hundreds of planar optic glass sheets bonded together with a cladding layer between each sheet where each glass sheet represents a vertical line of resolution. The display is 9 inches wide by 5 inches high and approximately 1 inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

Energy Technology Data Exchange (ETDEWEB)

Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee [Department of Radiological Sciences, University of California, Irvine, California 92697 (United States)

2010-03-15

Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

International Nuclear Information System (INIS)

Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

2010-01-01

Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

Flat panel detectors - closing the (digital) gap in chest and skeletal radiology

International Nuclear Information System (INIS)

Reiff, Kurt J.

1999-01-01

In the radiological department today the majority of all X-ray procedures on chest and skeletal radiography is performed with classical film-screen-systems. Using digital luminescence radiography (DLR or CR, which stands for Computed Radiography) as a technique has shown a way to replace this 100-year-old procedure of doing general radiography work by acquiring the X-rays digitally via phosphor screens, but this approach has faced criticism from lots of radiologists world wide and therefore has not been widely accepted except in the intensive care environment. A new technology is now rising based on the use of so called flat panel X-ray (FD) detectors. Semi-conducting material detects the X-rays in digital form directly and creates an instantaneous image for display, distribution and diagnosis. This ability combined with a large field of view and -- compared to existing methods -- excellent detective quantum efficiency represents a revolutionary step for chest and skeletal radiography and will put basic X-ray-work back into the focus of radiological solutions. This paper will explain the basic technology of flat panel detectors, possible system solutions based on this new technology, aspects of the user interface influencing the system utilization and versatility as well as the possibility to redefine the patient examination process for chest and skeletal radiography. Furthermore the author discusses limitations for the first released systems, upgrades for the installed base and possible scenarios for the future. e.g. fluoroscopy or angiography application

Implementation of a program of quality assurance of image in an imaging system of flat panel portal

International Nuclear Information System (INIS)

Gomez Barrado, A.; Sanchez Jimenez, E.; Benitez, J. A.; Sanchez-Reyes, A.

2013-01-01

(IGRT) image-guided radiation therapy is the one in which images are used to locate the area of treatment. Modern irradiation systems are equipped with different modalities for obtaining images, such as flat panel systems, systems conebeam, tomoimagen, etc. This paper describes the start-up and the experience of a quality assurance program based on a flat panel portal Imaging System. (Author)

Recommendations for the performance rating of flat plate terrestrial photovoltaic solar panels

Science.gov (United States)

Treble, F. C.

1976-01-01

A review of recommendations for standardizing the performance rating of flat plate terrestrial solar panels is given to develop an international standard code of practice for performance rating. Required data to characterize the performance of a solar panel are listed. Other items discussed are: (1) basic measurement procedures; (2) performance measurement in natural sunlight and simulated sunlight; (3) standard solar cells; (4) the normal incidence method; (5) global method and (6) definition of peak power.

X-ray performance of a wafer-scale CMOS flat panel imager for applications in medical imaging and nondestructive testing

International Nuclear Information System (INIS)

Cha, Bo Kyung; Jeon, Seongchae; Seo, Chang-Woo

2016-01-01

This paper presents a wafer-scale complementary metal-oxide semiconductor (CMOS)-based X-ray flat panel detector for medical imaging and nondestructive testing applications. In this study, our proposed X-ray CMOS flat panel imager has been fabricated by using a 0.35 µm 1-poly/4-metal CMOS process. The pixel size is 100 µm×100 µm and the pixel array format is 1200×1200 pixels, which provide a field-of-view (FOV) of 120mm×120 mm. The 14.3-bit extended counting analog-to digital converter (ADC) with built-in binning mode was used to reduce the area and simultaneously improve the image resolution. The different screens such as thallium-doped CsI (CsI:Tl) and terbium gadolinium oxysulfide (Gd_2O_2S:Tb) scintillators were used as conversion materials for X-rays to visible light photons. The X-ray imaging performance such as X-ray sensitivity as a function of X-ray exposure dose, spatial resolution, image lag and X-ray images of various objects were measured under practical medical and industrial application conditions. This paper results demonstrate that our prototype CMOS-based X-ray flat panel imager has the significant potential for medical imaging and non-destructive testing (NDT) applications with high-resolution and high speed rate.

X-ray performance of a wafer-scale CMOS flat panel imager for applications in medical imaging and nondestructive testing

Energy Technology Data Exchange (ETDEWEB)

Cha, Bo Kyung, E-mail: goldrain99@kaist.ac.kr [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Jeon, Seongchae [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Seo, Chang-Woo [Department of Radiological Science, Yonsei University, Gangwon-do 220-710 (Korea, Republic of)

2016-09-21

This paper presents a wafer-scale complementary metal-oxide semiconductor (CMOS)-based X-ray flat panel detector for medical imaging and nondestructive testing applications. In this study, our proposed X-ray CMOS flat panel imager has been fabricated by using a 0.35 µm 1-poly/4-metal CMOS process. The pixel size is 100 µm×100 µm and the pixel array format is 1200×1200 pixels, which provide a field-of-view (FOV) of 120mm×120 mm. The 14.3-bit extended counting analog-to digital converter (ADC) with built-in binning mode was used to reduce the area and simultaneously improve the image resolution. The different screens such as thallium-doped CsI (CsI:Tl) and terbium gadolinium oxysulfide (Gd{sub 2}O{sub 2}S:Tb) scintillators were used as conversion materials for X-rays to visible light photons. The X-ray imaging performance such as X-ray sensitivity as a function of X-ray exposure dose, spatial resolution, image lag and X-ray images of various objects were measured under practical medical and industrial application conditions. This paper results demonstrate that our prototype CMOS-based X-ray flat panel imager has the significant potential for medical imaging and non-destructive testing (NDT) applications with high-resolution and high speed rate.

Visual and ocular effects from the use of flat-panel displays.

Science.gov (United States)

Porcar, Esteban; Pons, Alvaro M; Lorente, Amalia

2016-01-01

To evaluate the prevalence of eye symptoms in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. One hundred and sixteen VDU users with flat-panel display from an urban population participated in the study; their ages ranging from 20 to 34y. There were 60 females and 56 males. An eye examination to rule out the presence of significant uncorrected refractive errors, general binocular dysfunctions and eye conditions was carried out. In order to determine and quantify the type and nature of eye symptoms, participants were asked to answer written questionnaire and the results were grouped by gender, age and number of hours a day spent using a VDU. Seventy-two percent of participants reported eye symptoms related to VDU use. Eye symptoms from moderate-to-severe were found in 23% of participants. The main symptom was moderate-to-severe tired eyes (14%); followed by sensitivity to bright lights (12%), blurred vision at far distances (10%), eyestrain or dry eye or irritated or burning eyes (9%), difficulty in refocusing from one distance to another or headache (8%) and blurred vision at near or intermediate distances (<4%). Eye symptoms were greater among females (P=0.005) and increased with VDU use, markedly above 6h spent using a VDU in a typical day (P=0.01). Significant eye symptoms relate to VDU use often occur and should not be underestimated. The increasing use of electronic devices with flat-panel display should prompt users to take appropriate measures to prevent or to relieve the eye symptoms arising from their use.

Reduction of ring artifacts in CBCT: Detection and correction of pixel gain variations in flat panel detectors

International Nuclear Information System (INIS)

Altunbas, Cem; Lai, Chao-Jen; Zhong, Yuncheng; Shaw, Chris C.

2014-01-01

Purpose: In using flat panel detectors (FPD) for cone beam computed tomography (CBCT), pixel gain variations may lead to structured nonuniformities in projections and ring artifacts in CBCT images. Such gain variations can be caused by change in detector entrance exposure levels or beam hardening, and they are not accounted by conventional flat field correction methods. In this work, the authors presented a method to identify isolated pixel clusters that exhibit gain variations and proposed a pixel gain correction (PGC) method to suppress both beam hardening and exposure level dependent gain variations. Methods: To modulate both beam spectrum and entrance exposure, flood field FPD projections were acquired using beam filters with varying thicknesses. “Ideal” pixel values were estimated by performing polynomial fits in both raw and flat field corrected projections. Residuals were calculated by taking the difference between measured and ideal pixel values to identify clustered image and FPD artifacts in flat field corrected and raw images, respectively. To correct clustered image artifacts, the ratio of ideal to measured pixel values in filtered images were utilized as pixel-specific gain correction factors, referred as PGC method, and they were tabulated as a function of pixel value in a look-up table. Results: 0.035% of detector pixels lead to clustered image artifacts in flat field corrected projections, where 80% of these pixels were traced back and linked to artifacts in the FPD. The performance of PGC method was tested in variety of imaging conditions and phantoms. The PGC method reduced clustered image artifacts and fixed pattern noise in projections, and ring artifacts in CBCT images. Conclusions: Clustered projection image artifacts that lead to ring artifacts in CBCT can be better identified with our artifact detection approach. When compared to the conventional flat field correction method, the proposed PGC method enables characterization of nonlinear

Evaluation of a flat panel digital radiographic system for low-dose portable imaging of neonates

International Nuclear Information System (INIS)

Samei, Ehsan; Hill, Jeanne G.; Frey, G. Donald; Southgate, W. Michael; Mah, Eugene; Delong, David

2003-01-01

The purpose of this study was to evaluate the clinical utility of an investigational flat-panel digital radiography system for low-dose portable neonatal imaging. Thirty image-pairs from neonatal intensive care unit patients were acquired with a commercial Computed Radiography system (Agfa, ADC 70), and with the investigational system (Varian, Paxscan 2520) at one-quarter of the exposure. The images were evaluated for conspicuity and localization of the endings of ancillary catheters and tubes in two observer performance experiments with three pediatric radiologists and three neonatologists serving as observers. The results indicated no statistically significant difference in diagnostic quality between the images from the investigational system and from CR. Given the investigational system's superior resolution and noise characteristics, observer results suggest that the high detective quantum efficiency of flat-panel digital radiography systems can be utilized to decrease the radiation dose/exposure to neonatal patients, although post-processing of the images remains to be optimized. The rapid availability of flat-panel images in portable imaging was found to be an added advantage for timely clinical decision-making

Investigation of the dosimetric properties of an a-Si flat panel epid

International Nuclear Information System (INIS)

Fielding, A.L.; Jahangir, S.T.

2004-01-01

Full text: Electronic portal imaging devices (EPIDs) are primarily used as an electronic replacement for film to verify the set-up of radiotherapy patients based on imaged anatomy. There has recently been much interest in the use of amorphous silicon (a-Si) flat panel EPIDs for dosimetric verification in radiotherapy. The work presented here has been carried out to determine their suitability for dosimetric applications by investigating some of the basic response characteristics and the implications these might have. The measurements reported in this paper were performed using 6-MV photon beams from an Elekta Precise linear accelerator fitted with Elekta iViewGT amorphous silicon flat panel EPIDs. Measurements were performed to investigate the response of the EPID as a function of exposure and field size. Similar measurements were made with an ionisation chamber for comparison. Further measurements were carried out to investigate the response of the EPID to multiple low dose exposures (e.g. 5x2 MU) such as might be encountered in Intensity Modulated Radiotherapy (IMRT). This was compared with the response to a single high dose exposure (e.g. 10 MU) and repeated for a range of exposures. The results show the response of the EPID, to a good approximation, to be linear with dose over the range of 1 -200 MU. However, 'under-responses' in the EPID of up to 5% were seen at the lowest exposures. For multiple low dose segments the sum of the EPID responses was found to be less than the response to the same total exposure in a single large segment. This effect reduces with increase in the magnitude of the low dose segments. The variation in EPID response with field size was found to be greater than that indicated by the ionisation chamber. The results show that the a-Si detector responds to dose, to a good approximation, in a linear manner. The EPID under-response at low doses is thought to be related to the so called ghosting effect. Each image frame has a residual

Transparent Solar Concentrator for Flat Panel Display

Science.gov (United States)

Yeh, Chia-Hung; Chang, Fuh-Yu; Young, Hong-Tsu; Hsieh, Tsung-Yen; Chang, Chia-Hsiung

2012-06-01

A new concept of the transparent solar concentrator for flat panel display is experimentally demonstrated without adversely affecting the visual effects. The solar concentrator is based on a solar light-guide plate with micro prisms, not only increasing the absorption area of solar energy but also enhancing the conversion efficiency. The incident light is guided by the designed solar light-guide plate according to the total internal reflection (TIR), and converted into electrical power by photovoltaic solar cells. The designed transparent solar concentrator was made and measured with high transparency, namely 94.8%. The developed solar energy system for display can store energy and supply the bias voltage to light on two light-emitting diodes (LEDs) successfully.

Flat panel computed tomography of human ex vivo heart and bone specimens: initial experience

Energy Technology Data Exchange (ETDEWEB)

Nikolaou, Konstantin; Becker, Christoph R.; Reiser, Maximilian F. [Ludwig-Maximilians-University, Department of Clinical Radiology, Munich (Germany); Flohr, Thomas; Stierstorfer, Karl [CT Division, Siemens Medical Solutions, Forchheim (Germany)

2005-02-01

The aim of this technical investigation was the detailed description of a prototype flat panel detector computed tomography system (FPCT) and its initial evaluation in an ex vivo setting. The prototype FPCT scanner consists of a conventional radiographic flat panel detector, mounted on a multi-slice CT scanner gantry. Explanted human ex vivo heart and foot specimens were examined. Images were reformatted with various reconstruction algorithms and were evaluated for high-resolution anatomic information. For comparison purposes, the ex vivo specimens were also scanned with a conventional 16-detector-row CT scanner (Sensation 16, Siemens Medical Solutions, Forchheim, Germany). With the FPCT prototype used, a 1,024 x 768 resolution matrix can be obtained, resulting in an isotropic voxel size of 0.25 x 0.25 x 0.25 mm at the iso-center. Due to the high spatial resolution, very small structures such as trabecular bone or third-degree, distal branches of coronary arteries could be visualized. This first evaluation showed that flat panel detector systems can be used in a cone-beam computed tomography scanner and that very high spatial resolutions can be achieved. However, there are limitations for in vivo use due to constraints in low contrast resolution and slow scan speed. (orig.)

Modelling of scintillator based flat-panel detectors with Monte-Carlo simulations

International Nuclear Information System (INIS)

Reims, N; Sukowski, F; Uhlmann, N

2011-01-01

Scintillator based flat panel detectors are state of the art in the field of industrial X-ray imaging applications. Choosing the proper system and setup parameters for the vast range of different applications can be a time consuming task, especially when developing new detector systems. Since the system behaviour cannot always be foreseen easily, Monte-Carlo (MC) simulations are keys to gain further knowledge of system components and their behaviour for different imaging conditions. In this work we used two Monte-Carlo based models to examine an indirect converting flat panel detector, specifically the Hamamatsu C9312SK. We focused on the signal generation in the scintillation layer and its influence on the spatial resolution of the whole system. The models differ significantly in their level of complexity. The first model gives a global description of the detector based on different parameters characterizing the spatial resolution. With relatively small effort a simulation model can be developed which equates the real detector regarding signal transfer. The second model allows a more detailed insight of the system. It is based on the well established cascade theory, i.e. describing the detector as a cascade of elemental gain and scattering stages, which represent the built in components and their signal transfer behaviour. In comparison to the first model the influence of single components especially the important light spread behaviour in the scintillator can be analysed in a more differentiated way. Although the implementation of the second model is more time consuming both models have in common that a relatively small amount of system manufacturer parameters are needed. The results of both models were in good agreement with the measured parameters of the real system.

On Energy Balance and Production Costs in Tubular and Flat Panel Photobioreactors

NARCIS (Netherlands)

Norsker, N.H.; Barbosa, M.J.; Vermue, M.H.; Wijffels, R.H.

2012-01-01

Reducing mixing in both flat panel and tubular photobioreactors can result in a positive net energy balance with state-of-the-art technology and Dutch weather conditions. In the tubular photobioreactor, the net energy balance becomes positive at velocities <0.3 ms-1, at which point the biomass

Quantitative digital radiography with two dimensional flat panels

International Nuclear Information System (INIS)

Dinten, J.M.; Robert-Coutant, C.; Darboux, M.

2003-01-01

Purpose: Attenuation law relates radiographic images to irradiated object thickness and chemical composition. Film radiography exploits qualitatively this property for diagnosis. Digital radiographic flat panels present large dynamic range, reproducibility and linearity properties which open the gate for quantification. We will present, through two applications (mammography and bone densitometry), an approach to extract quantitative information from digital 2D radiographs. Material and method: The main difficulty for quantification is X-rays scatter, which superimposes to acquisition data. Because of multiple scatterings and 3D geometry dependence, it cannot be directly exploited through an exact analytical model. Therefore we have developed an approach for its estimation and subtraction from medical radiographs, based on approximations and derivations of analytical models of scatter formation in human tissues. Results: In digital mammography, the objective is to build a map of the glandular tissue thickness. Its separation from fat tissue is based on two equations: height of compression and attenuation. This last equation needs X-Rays scatter correction. In bone densitometry, physicians look for quantitative bone mineral density. Today, clinical DEXA systems use collimated single or linear detectors to eliminate scatter. This scanning technology induces poor image quality. By applying our scatter correction approach, we have developed a bone densitometer using a digital flat panel (Lexxos, DMS). It provides with accurate and reproducible measurements while presenting radiological image quality. Conclusion: These applications show how information processing, and especially X-Rays scatter processing, enables to extract quantitative information from digital radiographs. This approach, associated to Computer Aided Diagnosis algorithms or reconstructions algorithms, gives access to useful information for diagnosis. (author)

Volumetry of human molars with flat panel-based volume CT in vitro

NARCIS (Netherlands)

Hannig, C.; Krieger, E.; Dullin, C.; Merten, H.A.; Attin, T.; Grabbe, E.; Heidrich, G.

2006-01-01

The flat panel-based volume computed tomography (fpVCT) is a new CT device applicable for experimental, three-dimensional evaluation of teeth at a resolution of about 150 microm in the high contrast region. The aim of this study was to investigate whether fpVCT was suitable for quantification of the

Flat-screen detector systems in skeletal radiology

International Nuclear Information System (INIS)

Grampp, S.; Czerny, C.; Krestan, C.; Henk, C.; Heiner, L.; Imhof, H.

2003-01-01

Implementation of flat-panel detectors and digital integration of the technique instead of the use of conventional radiographs leads to a shortening of the work process. With flat-panel technology the image production process is shortened by more than 30%. Major advantages in the implementation of integrated RIS, PACS and flat-panel detector system are increases in quality because most mistakes in picture labeling can be avoided, easier handling without the need for cassettes, and the possibility of image post-processing. The diagnostic quality of the images in the field of musculoskeletal radiology is, in comparison to conventional radiographs, at least adequate and in most cases markedly improved with a marked reduction in radiation exposure of around 30-50%. With respect to the numerous advantages of the digital techniques and especially flat-panel technology there is a very high likelihood that conventional radiographs will be substituted in the coming years, even though the cost of the new technology is currently significantly higher compared to conventional systems. (orig.) [de

Resolution requirements for monitor viewing of digital flat-panel detector radiographs: a contrast detail analysis

International Nuclear Information System (INIS)

Peer, Siegfried; Giacomuzzi, Salvatore M.; Peer, Regina; Gassner, Eva; Steingruber, Iris; Jaschke, Werner

2003-01-01

With the introduction of digital flat-panel detector systems into clinical practice, the still unresolved question of resolution requirements for picture archiving communication system (PACS) workstation monitors has gained new momentum. This contrast detail analysis was thus performed to define the differences in observer performance in the detection of small low-contrast objects on clinical 1K and 2K monitor workstations. Images of the CDRAD 2.0 phantom were acquired at varying exposures on an indirect-type digital flat-panel detector. Three observers evaluated a total of 15 images each with respect to the threshold contrast for each detail size. The numbers of correctly identified objects were determined for all image subsets. No significant difference in the correct detection ratio was detected among the observers; however, the difference between the two types of workstations (1K vs 2K monitors) despite less than 3% was significant at a 95% confidence level. Slight but statistically significant differences exist in the detection of low-contrast nodular details visualized on 1K- and 2K-monitor workstations. Further work is needed to see if this result holds true also for comparison of clinical flat-panel detector images and may, for example, exert an influence on the diagnostic accuracy of chest X-ray readings. (orig.)

Attenuated phase-shift mask (PSM) blanks for flat panel display

Science.gov (United States)

Kageyama, Kagehiro; Mochizuki, Satoru; Yamakawa, Hiroyuki; Uchida, Shigeru

2015-10-01

The fine pattern exposure techniques are required for Flat Panel display applications as smart phone, tablet PC recently. The attenuated phase shift masks (PSM) are being used for ArF and KrF photomask lithography technique for high end pattern Semiconductor applications. We developed CrOx based large size PSM blanks that has good uniformity on optical characteristics for FPD applications. We report the basic optical characteristics and uniformity, stability data of large sized CrOx PSM blanks.

Progress toward clinical implementation of the first flat-panel amorphous silicon imager

International Nuclear Information System (INIS)

Antonuk, Larry E.; El-Mohri, Youcef; Weidong, Huang; Sandler, Howard; Siewerdsen, Jeffrey H.; Yorkston, John

1995-01-01

the flat-panel imager are quite comparable to that of digitized film images. Even at this early stage, the overall image quality is sufficient to allow identification of skeletal anatomical landmarks and field edges permitting identification of gross setup errors. Conclusions: The image quality in this initial demonstration, though limited by array defects and the design of the current acquisition system, strongly supports the hypothesis that this technology will form the basis of a very compact, powerful imaging tool for radiotherapy localization and verification. The intrinsic properties of flat-panel megavoltage imagers strongly indicates that highly radiation damage resistant devices offering excellent contrast and spatial resolution, limited only by the nature and source of the radiation, are to be expected. Image quality is likely to exceed that of existing technologies at equivalent doses. Alternatively, clinically useful images at significantly lower doses is also a definite possibility. The realization of this potential will require an understanding of the origin of various noise sources, improvements in the acquisition electronics, as well as a reduction in the number of array defects. Notwithstanding the present limitations, the clinical utility of the technology is demonstrated and future enhancements are expected to make it an extremely valuable tool. The development of a clinical prototype offering high quality images over an area ultimately as large as ∼52x52 cm 2 is anticipated

Clinical evaluation of digital angiographic system equipped with the Safire' flat-panel detector of a direct conversion type

International Nuclear Information System (INIS)

Miura, Yoshiaki; Miura, Yusuke; Goto, Keiichi

2003-01-01

This report presents a report on clinical evaluation of our newly developed flat-panel X-ray detector of a direct conversion type, designed to provide images of a resolution higher than, or at least equal to, that ensured by X-ray photographic films, in clinical digital X-ray cinematography. This new detector was named 'Safire' the acronym of 'Shimadzu advanced flat imaging receptor', emphasizing its high technological level, such as the capability to ensure high quality of images. The clinical evaluation of Shimadzu DIGITEX Premier digital angiography system, equipped with this new flat-panel X-ray detector of a direct conversion type, has been started in March, 2003, at the Kokura Memorial Hospital in Kyushu, Japan. (author)

Digital chest radiography with an amorphous silicon flat-panel-detector versus a storage-phosphor system: comparison of soft-copy images

International Nuclear Information System (INIS)

Lee, Hyun Ju; Im, Jung Gi; Goo, Jin Mo; Lee, Chang Hyun

2006-01-01

We compared the soft-copy images produced by an amorphous silicon flat-panel-detector system with the images produced by a storage-phosphor radiography system for their ability to visualize anatomic regions of the chest. Two chest radiologists independently analyzed 234 posteroanterior chest radiographs obtained from 78 patients on high-resolution liquid crystal display monitors (2560 x 2048 x 8 bits). In each patient, one radiograph was obtained with a storage-phosphor system, and two radiographs were obtained via amorphous silicon flat-panel-detector radiography with and without spatial frequency filtering. After randomizing the 234 images, the interpreters rated the visibility and radiographic quality of 11 different anatomic regions. Each image was ranked on a five-point scale (1 = not visualized, 2 = poor visualization, 3 = fair visualization, 4 = good visualization, and 5 = excellent visualization). The statistical difference between each system was determined using the Wilcoxon's signed rank test. The visibility of three anatomic regions (hilum, heart border and ribs), as determined by the chest radiologist with 14 years experience (ρ < 0.05) and the visibility of the thoracic spine, as determined by the chest radiologist with 8 years experience (ρ = 0.036), on the amorphous silicon flat-panel-detector radiography prior to spatial frequency filtering were significantly superior to that on the storage-phosphor radiography. The visibility of 11 anatomic regions, as determined by the chest radiologist with 14 years experience (ρ < 0.0001) and the visibility of five anatomic regions (unobscured lung, rib, proximal airway, thoracic spine and overall appearance), as determined by the chest radiologist with 8 years experience (ρ < 0.05), on the amorphous silicon flat-panel-detector radiography after spatial frequency filtering were significantly superior to that on the storage-phosphor radiography. The amorphous silicon flat-panel-detector system depicted the

Flat Panel PMT: advances in position sensitive photodetection

International Nuclear Information System (INIS)

Pani, R.; Pellegrini, R.; Trotta, C.; Cinti, M.N.; Bennati, P.; Trotta, G.; Iurlaro, G.; Montani, L.; Ridolfi, S.; Cusanno, F.; Garibaldi, F.

2003-01-01

Over the last ten years there was being a strong advancement in photodetection. Different application fields are involved in their use in particular high energy physics, astrophysics and nuclear medicine. They usually work by coupling a scintillation crystal and more recent scintillation arrays with pixel size as small as 0.5 mm. PSPMT represents today the most ready technology for photodetection with large detection areas and very high spatial resolution. Flat panel PMT represents the last technological advancement. Its dimension is 50x50 mm 2 with a narrow peripheral dead zone (0.5 mm final goal). Its compactness allow to assemble different modules closely packed, achieving large detection areas with an effective active area of 97%. In this paper we analyze the imaging performances of PSPMT by coupling two scintillation arrays and by light spot scanning of photocathode to evaluate the linearity position response, spatial resolution and uniformity gain response as a function of light distribution spread and the number of photoelectrons generated on photocathode. The results point out a very narrow PMT intrinsic charge spread and low cross-talk between anodes. Energy resolution and spatial resolution show a good linearity with DRF variation. An unexpected intra-anode gain variation is carried out. In this paper we present the results obtained with this PSPMT regarding imaging performances principally addressed to nuclear medicine application

Synchrotron applications of an amorphous silicon flat-panel detector

International Nuclear Information System (INIS)

Lee, J. H.; Can Aydiner, C.; Almer, J.; Bernier, J.; Chapman, K. W.; Chupas, P. J.; Haeffner, D.; Kump, K.; Lee, P. L.; Lienert, U.; Miceli, A.; Vera, G.; LANL; GE Healthcare

2008-01-01

A GE Revolution 41RT flat-panel detector (GE 41RT) from GE Healthcare (GE) has been in operation at the Advanced Photon Source for over two years. The detector has an active area of 41 cm x 41 cm with 200 (micro)m x 200 (micro)m pixel size. The nominal working photon energy is around 80 keV. The physical set-up and utility software of the detector system are discussed in this article. The linearity of the detector response was measured at 80.7 keV. The memory effect of the detector element, called lag, was also measured at different exposure times and gain settings. The modulation transfer function was measured in terms of the line-spread function using a 25 (micro)m x 1 cm tungsten slit. The background (dark) signal, the signal that the detector will carry without exposure to X-rays, was measured at three different gain settings and with exposure times of 1 ms to 15 s. The radial geometric flatness of the sensor panel was measured using the diffraction pattern from a CeO 2 powder standard. The large active area and fast data-capturing rate, i.e. 8 frames s -1 in radiography mode, 30 frames s -1 in fluoroscopy mode, make the GE 41RT one of a kind and very versatile in synchrotron diffraction. The loading behavior of a Cu/Nb multilayer material is used to demonstrate the use of the detector in a strain-stress experiment. Data from the measurement of various samples, amorphous SiO 2 in particular, are presented to show the detector effectiveness in pair distribution function measurements

A novel heuristic for optimization aggregate production problem: Evidence from flat panel display in Malaysia

Science.gov (United States)

Al-Kuhali, K.; Hussain M., I.; Zain Z., M.; Mullenix, P.

2015-05-01

Aim: This paper contribute to the flat panel display industry it terms of aggregate production planning. Methodology: For the minimization cost of total production of LCD manufacturing, a linear programming was applied. The decision variables are general production costs, additional cost incurred for overtime production, additional cost incurred for subcontracting, inventory carrying cost, backorder costs and adjustments for changes incurred within labour levels. Model has been developed considering a manufacturer having several product types, which the maximum types are N, along a total time period of T. Results: Industrial case study based on Malaysia is presented to test and to validate the developed linear programming model for aggregate production planning. Conclusion: The model development is fit under stable environment conditions. Overall it can be recommended to adapt the proven linear programming model to production planning of Malaysian flat panel display industry.

Designing, Modeling, Constructing, and Testing a Flat Panel Speaker and Sound Diffuser for a Simulator

Science.gov (United States)

Dillon, Christina

2013-01-01

The goal of this project was to design, model, build, and test a flat panel speaker and frame for a spherical dome structure being made into a simulator. The simulator will be a test bed for evaluating an immersive environment for human interfaces. This project focused on the loud speakers and a sound diffuser for the dome. The rest of the team worked on an Ambisonics 3D sound system, video projection system, and multi-direction treadmill to create the most realistic scene possible. The main programs utilized in this project, were Pro-E and COMSOL. Pro-E was used for creating detailed figures for the fabrication of a frame that held a flat panel loud speaker. The loud speaker was made from a thin sheet of Plexiglas and 4 acoustic exciters. COMSOL, a multiphysics finite analysis simulator, was used to model and evaluate all stages of the loud speaker, frame, and sound diffuser. Acoustical testing measurements were utilized to create polar plots from the working prototype which were then compared to the COMSOL simulations to select the optimal design for the dome. The final goal of the project was to install the flat panel loud speaker design in addition to a sound diffuser on to the wall of the dome. After running tests in COMSOL on various speaker configurations, including a warped Plexiglas version, the optimal speaker design included a flat piece of Plexiglas with a rounded frame to match the curvature of the dome. Eight of these loud speakers will be mounted into an inch and a half of high performance acoustic insulation, or Thinsulate, that will cover the inside of the dome. The following technical paper discusses these projects and explains the engineering processes used, knowledge gained, and the projected future goals of this project

Clinical evaluation of digital angiographic system equipped with the Safire' flat-panel detector of a direct conversion type

Energy Technology Data Exchange (ETDEWEB)

Miura, Yoshiaki; Miura, Yusuke; Goto, Keiichi [Shimadzu Corporation, Medical Systems Division, Research and Development, Kyoto (JP)] [and others

2003-06-01

This report presents a report on clinical evaluation of our newly developed flat-panel X-ray detector of a direct conversion type, designed to provide images of a resolution higher than, or at least equal to, that ensured by X-ray photographic films, in clinical digital X-ray cinematography. This new detector was named 'Safire' the acronym of 'Shimadzu advanced flat imaging receptor', emphasizing its high technological level, such as the capability to ensure high quality of images. The clinical evaluation of Shimadzu DIGITEX Premier digital angiography system, equipped with this new flat-panel X-ray detector of a direct conversion type, has been started in March, 2003, at the Kokura Memorial Hospital in Kyushu, Japan. (author)

Wind loads on flat plate photovoltaic array fields

Science.gov (United States)

Miller, R. D.; Zimmerman, D. K.

1981-01-01

The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads. The arrays located at the outer boundary of an array field have a protective influence on the interior arrays of the field. A significant decrease of the array wind loads were recorded in the wind tunnel test on array panels located behind a fence and/or interior to the array field compared to the arrays on the boundary and unprotected from the wind. The magnitude of this decrease was the same whether caused by a fence or upwind arrays.

Target aligned heliostat field layout for non-flat terrrain

CSIR Research Space (South Africa)

Buck, R

2012-05-01

Full Text Available The layout for a solar tower test facility for CSIR, Pretoria, is described. The solar tower system is designed for 400kWth receiver outlet power. The heliostat field layout takes into account both the real (non-flat) topography of the terrain...

Flat-panel video resolution LED display system

Science.gov (United States)

Wareberg, P. G.; Kennedy, D. I.

The system consists of a 128 x 128 element X-Y addressable LED array fabricated from green-emitting gallium phosphide. The LED array is interfaced with a 128 x 128 matrix TV camera. Associated electronics provides for seven levels of grey scale above zero with a grey scale ratio of square root of 2. Picture elements are on 0.008 inch centers resulting in a resolution of 125 lines-per-inch and a display area of approximately 1 sq. in. The LED array concept lends itself to modular construction, permitting assembly of a flat panel screen of any desired size from 1 x 1 inch building blocks without loss of resolution. A wide range of prospective aerospace applications exist extending from helmet-mounted systems involving small dedicated arrays to multimode cockpit displays constructed as modular screens. High-resolution LED arrays are already used as CRT replacements in military film-marking reconnaissance applications.

Image quality analysis of vibration effects In C-arm-flat panel X-ray imaging

NARCIS (Netherlands)

Snoeren, R.M.; Kroon, J.N.; With, de P.H.N.

2011-01-01

The motion of C-arm scanning X-ray systems may result in vibrations of the imaging sub-system. In this paper, we connect C-arm system vibrations to Image Quality (IQ) deterioration for 2D angiography and 3D cone beam X-ray imaging, using large Flat Panel detectors. Vibrations will affect the

Extracting flat-field images from scene-based image sequences using phase correlation

Energy Technology Data Exchange (ETDEWEB)

Caron, James N., E-mail: Caron@RSImd.com [Research Support Instruments, 4325-B Forbes Boulevard, Lanham, Maryland 20706 (United States); Montes, Marcos J. [Naval Research Laboratory, Code 7231, 4555 Overlook Avenue, SW, Washington, DC 20375 (United States); Obermark, Jerome L. [Naval Research Laboratory, Code 8231, 4555 Overlook Avenue, SW, Washington, DC 20375 (United States)

2016-06-15

Flat-field image processing is an essential step in producing high-quality and radiometrically calibrated images. Flat-fielding corrects for variations in the gain of focal plane array electronics and unequal illumination from the system optics. Typically, a flat-field image is captured by imaging a radiometrically uniform surface. The flat-field image is normalized and removed from the images. There are circumstances, such as with remote sensing, where a flat-field image cannot be acquired in this manner. For these cases, we developed a phase-correlation method that allows the extraction of an effective flat-field image from a sequence of scene-based displaced images. The method uses sub-pixel phase correlation image registration to align the sequence to estimate the static scene. The scene is removed from sequence producing a sequence of misaligned flat-field images. An average flat-field image is derived from the realigned flat-field sequence.

Comparison of dose and image quality of a Flat-panel detector and an image intensifier

International Nuclear Information System (INIS)

Lazzaro, M.; Friedrich, B.Q.; Luz, R.M. da; Silva, A.M.M. da

2016-01-01

With the development of new technologies, have emerged new conversion methods of X-ray image, such as flat panel detectors. The aim of this work is the comparison of entrance surface air kerma (ESAK) and image quality between an image intensifier type of detector (A) and a flat panel (B). The ESAK was obtained by placing a ionization chamber under PMMA simulators of 10, 20 and 30 cm and the image quality was obtained by using the TOR "1"8FG simulator. The ESAK to the equipment A is higher when compared to the equipment B. The high contrast resolution is better for the equipment A for all thicknesses of simulators. The equipment A has low contrast resolution with a better viewing threshold for thicknesses of 10 and 20 cm, and a worse performance for 30 cm. It is concluded that the equipment B has ESAK smaller and despite having lower resolution, in almost all cases, have appropriate image quality for diagnosis. (author)

Evaluation the image obtained from X-ray flat-panel detectors utilizing a polycrystalline CdZnTe film as the conversion layer

International Nuclear Information System (INIS)

Tokuda, S.; Kishihara, H.; Kaino, M.; Sato, T.

2006-01-01

We can expect that fluoroscopic images with a high sensitivity and excellent detective efficiency can be obtained by using a semiconductor with a small W factor for the conversion layer of X-ray flat-panel detectors, which have experienced a rapid gain inpopularity for medical and non-destructive industrial inspection uses in recent years. We believe that polycrystalline CdZnTe film formed by the closed spaced sublimation (CSS) method is a promising conversion material for next-generation high efficiency X-ray flat-panel detectors, and have previously reported the results of feasibility studies. In this paper, we present an overview of X-ray flat-panel detectors and the features of CdZnTe film, then we describe the CSS method of deposition and evaluation of the physical characteristics of CdZnTe film, and finally we present the results of our fabrication and testing of proto-type detectors utilizing CdZnTe film. (author)

Flat-Panel Computed Tomography (DYNA-CT) in Neuroradiology. From High-Resolution Imaging of Implants to One-Stop-Shopping for Acute Stroke.

Science.gov (United States)

Doerfler, A; Gölitz, P; Engelhorn, T; Kloska, S; Struffert, T

2015-10-01

Originally aimed at improving standard radiography by providing higher absorption efficiency and a wider dynamic range, flat-panel detector technology has meanwhile got widely accepted in the neuroradiological community. Especially flat-panel detector computed tomography (FD-CT) using rotational C-arm mounted flat-panel detector technology is capable of volumetric imaging with a high spatial resolution. By providing CT-like images of the brain within the angio suite, FD-CT is able to rapidly visualize hemorrhage and may thus improve complication management without the need of patient transfer. As "Angiographic CT" FD-CT may be helpful during many diagnostic and neurointerventional procedures and for noninvasive monitoring and follow-up. In addition, spinal interventions and high-resolution imaging of the temporal bone might also benefit from FD-CT. Finally, using novel dynamic perfusion and angiographic protocols, FD-CT may provide functional information on brain perfusion and vasculature with the potential to replace standard imaging in selected acute stroke patients.

Dynamic modeling of the microalgae cultivation phase for energy production in open raceway ponds and flat panel photobioreactors

Directory of Open Access Journals (Sweden)

Matteo eMarsullo

2015-09-01

Full Text Available A dynamic model of microalgae cultivation phase is presented in this work. Two cultivation technologies are taken into account: the open raceway pond and the flat panel photobioreactor. For each technology, the model is able to evaluate the microalgae areal and volumetric productivity and the energy production and consumption. Differently from the most common existing models in literature, which deal with a specific part of the overall cultivation process, the model presented here includes all physical and chemical quantities that mostly affect microalgae growth: the equation of the specific growth rate for the microalgae is influenced by CO2 and nutrients concentration in the water, light intensity, temperature of the water in the reactor and by the microalgae species being considered. All these input parameters can be tuned to obtain reliable predictions. A comparison with experimental data taken from the literature shows that the predictions are consistent, slightly overestimating the productivity in case of closed photobioreactor. The results obtained by the simulation runs are consistent with those found in literature, being the areal productivity for the open raceway pond between 50 and 70 t/(ha*year in Southern Spain (Sevilla and Brazil (Petrolina and between 250 and 350 t/(ha*year for the flat panel photobioreactor in the same locations.

The effect of dose reduction on image quality in digital radiography using a flat-panel detector: experimental study in rabbits

International Nuclear Information System (INIS)

Jung, Sung Il; Goo, Jin Mo; Lee, Hyun Ju; Moon, Woo Kyung; Lim, Kun Young; Cho, Gyung Goo; Kim, Ji Hoon; Im, Jung Gi; Choi, Jang Yong; Nam, Sang Hee

2005-01-01

To evaluate the effect of dose reduction on image quality in digital radiography using a flat-panel detector. Digital radiographs of 30 rabbits were obtained at two different dose levels (33.23 μGY for the standard dose group and 20.09 μGY for the reduced dose group). The amorphous selenium-based flat-panel detector system had a panel size of 7 x 8.5 inches, a matrix of 1280 x 1536 (pixels?), and a pixel pitch of 138 μm. Four observers evaluated the soft-copy images on a high-resolution video monitor (2560 x 2048 x 8 bits) in random order. The observers rated the visibility of 13 different anatomic structures on a 5-point scale, viz, the retrocardiac lung, subdiaphragmatic lung, heart border, diaphragmatic border, proximal airway, unobscured lung, liver border, kidney border, bowel gas, flank stripe, ribs, and vertebrae in the mediastinal and abdominal regions. Statistical significance was determined using Wilcoxon's signed rank test. There was no statistically significant difference in the visibility of the anatomic structures on digital radiography between the standard and reduced dose groups. Digital radiography using an amorphous selenium-based flat-panel detector can preserve the image quality, though the dose is reduced to 40% of the standard level

The effect of dose reduction on image quality in digital radiography using a flat-panel detector: experimental study in rabbits

Energy Technology Data Exchange (ETDEWEB)

Jung, Sung Il; Goo, Jin Mo; Lee, Hyun Ju; Moon, Woo Kyung; Lim, Kun Young; Cho, Gyung Goo; Kim, Ji Hoon; Im, Jung Gi [Seoul National College of Medicine, Seoul (Korea, Republic of); Choi, Jang Yong; Nam, Sang Hee [Inje University, Seoul (Korea, Republic of)

2005-07-15

To evaluate the effect of dose reduction on image quality in digital radiography using a flat-panel detector. Digital radiographs of 30 rabbits were obtained at two different dose levels (33.23 {mu}GY for the standard dose group and 20.09 {mu}GY for the reduced dose group). The amorphous selenium-based flat-panel detector system had a panel size of 7 x 8.5 inches, a matrix of 1280 x 1536 (pixels?), and a pixel pitch of 138 {mu}m. Four observers evaluated the soft-copy images on a high-resolution video monitor (2560 x 2048 x 8 bits) in random order. The observers rated the visibility of 13 different anatomic structures on a 5-point scale, viz, the retrocardiac lung, subdiaphragmatic lung, heart border, diaphragmatic border, proximal airway, unobscured lung, liver border, kidney border, bowel gas, flank stripe, ribs, and vertebrae in the mediastinal and abdominal regions. Statistical significance was determined using Wilcoxon's signed rank test. There was no statistically significant difference in the visibility of the anatomic structures on digital radiography between the standard and reduced dose groups. Digital radiography using an amorphous selenium-based flat-panel detector can preserve the image quality, though the dose is reduced to 40% of the standard level.

Technical trends of large-size photomasks for flat panel displays

Science.gov (United States)

Yoshida, Koichiro

2017-06-01

Currently, flat panel displays (FPDs) are one of the main parts for information technology devices and sets. From 1990's to 2000's, liquid crystal displays (LCDs) and plasma displays had been mainstream FPDs. In the middle of 2000's, demand of plasma displays declined and organic light emitting diodes (OLEDs) newly came into FPD market. And today, major technology of FPDs are LCDs and OLEDs. Especially for mobile devices, the penetration of OLEDs is remarkable. In FPDs panel production, photolithography is the key technology as same as LSI. Photomasks for FPDs are used not only as original master of circuit pattern, but also as a tool to form other functional structures of FPDs. Photomasks for FPDs are called as "Large Size Photomasks(LSPMs)", since the remarkable feature is " Size" which reaches over 1- meter square and over 100kg. In this report, we discuss three LSPMs technical topics with FPDs technical transition and trend. The first topics is upsizing of LSPMs, the second is the challenge for higher resolution patterning, and the last is "Multi-Tone Mask" for "Half -Tone Exposure".

Performance Characteristic of a CsI(Tl) Flat Panel Detector Radiography System

International Nuclear Information System (INIS)

Jeong, Hoi Woun; Min, Jung Hwan; Kim, Jung Min; Park, Min Seok; Lee, Gaung Young

2012-01-01

The purpose of this work was to evaluate an amorphous silicon cesium iodide based indirect flat-panel detector (FPD) in terms of their modulation transfer function (MTF), Wiener spectrum (WS, or noise power spectrum, NPS), and detective quantum efficiency (DQE). Measurements were made on flat-panel detector using the International Electrotechnical Commission (IEC) defined RQA3, RQA5, RQA7, and RQA9 radiographic technique. The MTFs of the systems were measured using an edge method. The WS(NPS) of the systems were determined for a range of exposure levels by two-dimensional (2D). Fourier analysis of uniformly exposed radiographs. The DQEs were assessed from the measured MTF, WS(NPS), exposure, and estimated ideal signal-to-noise ratios. Characteristic curve in the RQA3 showed difference in the characteristic curve from RQA5, RQA7, RQA9. MTFs were not differences according to x-ray beam quality. WS(NPS) was reduced with increasing dose, and RQA 3, RQA5, RQA7, RQA9 as the order is reduced. DQE represented the best in the 1mR, RQA 3, RQA5, RQA7, RQA9 decrease in the order. The physical imaging characteristics of FPD may also differ from input beam quality. This study gives an initial motivation that the physical imaging characteristics of FPD is an important issue for the right use of digital radiography system.

Performance Characteristic of a CsI(Tl) Flat Panel Detector Radiography System

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hoi Woun [Dept. of Radiological Science, Baekseok Culture University, Seoul (Korea, Republic of); Min, Jung Hwan [Dept. of Radiological Technology, Shingu University, Seongnam (Korea, Republic of); Kim, Jung Min [Dept. of Radiological Science, Korea University, Health Science College, Seoul (Korea, Republic of); Park, Min Seok [Korea Institue of Radiological and Medical Sicences, Research Institute of Radiologycal and Medical Sciences, Seoul (Korea, Republic of); Lee, Gaung Young [National Institute of Food and Drug Safety Evaluation, Seoul (Korea, Republic of)

2012-06-15

The purpose of this work was to evaluate an amorphous silicon cesium iodide based indirect flat-panel detector (FPD) in terms of their modulation transfer function (MTF), Wiener spectrum (WS, or noise power spectrum, NPS), and detective quantum efficiency (DQE). Measurements were made on flat-panel detector using the International Electrotechnical Commission (IEC) defined RQA3, RQA5, RQA7, and RQA9 radiographic technique. The MTFs of the systems were measured using an edge method. The WS(NPS) of the systems were determined for a range of exposure levels by two-dimensional (2D). Fourier analysis of uniformly exposed radiographs. The DQEs were assessed from the measured MTF, WS(NPS), exposure, and estimated ideal signal-to-noise ratios. Characteristic curve in the RQA3 showed difference in the characteristic curve from RQA5, RQA7, RQA9. MTFs were not differences according to x-ray beam quality. WS(NPS) was reduced with increasing dose, and RQA 3, RQA5, RQA7, RQA9 as the order is reduced. DQE represented the best in the 1mR, RQA 3, RQA5, RQA7, RQA9 decrease in the order. The physical imaging characteristics of FPD may also differ from input beam quality. This study gives an initial motivation that the physical imaging characteristics of FPD is an important issue for the right use of digital radiography system.

Digital radiography with a large-scale electronic flat-panel detector vs screen-film radiography: observer preference in clinical skeletal diagnostics

International Nuclear Information System (INIS)

Hamers, S.; Freyschmidt, J.; Neitzel, U.

2001-01-01

The imaging performance of a recently developed digital flat-panel detector system was compared with conventional screen-film imaging in an observer preference study. In total, 34 image pairs of various regions of the skeleton were obtained in 24 patients; 30 image pairs were included in the study. The conventional images were acquired with 250- and 400-speed screen-film combinations, using the standard technique of our department. Within hours, the digital images were obtained using identical exposure parameters. The digital system employed a large-area (43 x 43 cm) flat-panel detector based on amorphous silicon (Trixell Pixium 4600), integrated in a Bucky table. Six radiologists independently evaluated the image pairs with respect to image latitude, soft tissue rendition, rendition of the periosteal and enosteal border of cortical bone, rendition of cancellous bone and the visibility of potentially present pathological changes, using a subjective five-point scale. The digital images were rated significantly (p=0.001) better than the screen-film images with respect to soft tissue rendition and image latitude. Also the rendition of the cancellous bone and the periosteal and enosteal border of the cortical bone was rated significantly (p=0.05) better for the flat-panel detector. The visibility of pathological lesions was equivalent; only large-area sclerotic lesions (n=2) were seen superiorly on screen-film images. The new digital flat-panel detector based on amorphous silicon appears to be at least equivalent to conventional screen-film combinations for skeletal examinations, and in most respects even superior. (orig.)

Characteristics and applications of a flat panel computer tomography system

International Nuclear Information System (INIS)

Knollmann, F.; Valencia, R.; Obenauer, S.; Buhk, J.H.

2006-01-01

Purpose: to assess a new flat panel volume computed tomography (FP-VCT) with very high isotropic spatial resolution as well as high Z-axis coverage. Materials and Methods: The prototype of an FP-VCT scanner with a detector cell size of 0.2 mm was used for numerous phantom studies, specimen examinations, and animal research projects. Results: The high spatial resolution of the new system can be used to accurately determine solid tumor volume, thus allowing for earlier assessment of the therapeutic response. In animal experimentation, whole-body perfusion mapping of mice is feasible. The high spatial resolution also improves the classification of coronary artery atherosclerotic plaques in the isolated post mortem human heart. With the depiction of intramyocardial segments of the coronary arteries, investigations of myocardial collateral circulation are feasible. In skeletal applications, an accurate analysis of the smallest bony structures, e.g., petrous bone and dental preparations, can be successfully performed, as well as investigations of repetitive studies of fracture healing and the treatment of osteoporosis. Conclusion: The introduction of FP-VCT opens up new applications for CT, including the field of molecular imaging, which are highly attractive for future clinical applications. Present limitations include limited temporal resolution and necessitate further improvement of the system. (orig.)

Qualification test results for DOE solar photovoltaic flat panel procurement - PRDA 38

Science.gov (United States)

Griffith, J. S.

1980-01-01

Twelve types of prototypes modules for the DOE Photovoltaic Flat Panel Procurement (PRDA 38) were subjected to qualification tests at the Jet Propulsion Laboratory according to a new specification. Environmental exposures were carried out separately and included temperature cycling, humidity, wind simulation, and hail. The most serious problems discovered were reduced insulation resistance to ground and ground continuity of the metal frames, electrical degradation, erratic power readings, and delamination. The electrical and physical characteristics of the newly received modules are also given.

Scan equalization digital radiography (SEDR) implemented with an amorphous selenium flat-panel detector: initial experience

Energy Technology Data Exchange (ETDEWEB)

Liu Xinming; Lai Chaojen; Chen Lingyun; Han Tao; Zhong Yuncheng; Shen Youtao; Wang Tianpeng; Shaw, Chris C [Department of Imaging Physics, Digital Imaging Research Laboratory, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030-4009 (United States)], E-mail: xliu@di.mdacc.tmc.edu

2009-11-21

It is well recognized in projection radiography that low-contrast detectability suffers in heavily attenuating regions due to excessively low x-ray fluence to the image receptor and higher noise levels. Exposure equalization can improve image quality by increasing the x-ray exposure to heavily attenuating regions, resulting in a more uniform distribution of exposure to the detector. Image quality is also expected to be improved by using the slot-scan geometry to reject scattered radiation effectively without degrading primary x-rays. This paper describes the design of a prototype scan equalization digital radiography (SEDR) system implemented with an amorphous silicon (a-Si) thin-film transistor (TFT) array-based flat-panel detector. With this system, slot-scan geometry with alternate line erasure and readout (ALER) technique was used to achieve scatter rejection. A seven-segment beam height modulator assembly was mounted onto the fore collimator to regulate exposure regionally for chest radiography. The beam modulator assembly, consisting of micro linear motors, lead screw cartridge with lead (Pb) beam blockers attached, position feedback sensors and motor driver circuitry, has been tested and found to have an acceptable response for exposure equalization in chest radiography. An anthropomorphic chest phantom was imaged in the posterior-anterior (PA) view under clinical conditions. Scatter component, primary x-rays, scatter-to-primary ratios (SPRs) and primary signal-to-noise ratios (PSNRs) were measured in the SEDR images to evaluate the rejection and redistribution of scattered radiation, and compared with those for conventional full-field imaging with and without anti-scatter grid methods. SPR reduction ratios (SPRRRs, defined as the differences between the non-grid full-field SPRs and the reduced SPRs divided by the former) yielded approximately 59% for the full-field imaging with grid and 82% for the SEDR technique in the lungs, and 77% for the full-field

No-contact method of determining average working-surface temperature of plate-type radiation-absorbing thermal exchange panels of flat solar collectors for heating heat-transfer fluid

International Nuclear Information System (INIS)

Avezova, N.R.; Avezov, R.R.

2015-01-01

A brand new no-contact method of determining the average working-surface temperature of plate-type radiation-absorbing thermal exchange panels (RATEPs) of flat solar collectors (FSCs) for heating a heat-transfer fluid (HTF) is suggested on the basis of the results of thermal tests in full-scale quasistationary conditions. (authors)

Development of flat panel X-ray detector utilizing a CdZnTe film as conversion layer

International Nuclear Information System (INIS)

Tokuda, Satoshi; Kishihara, Hiroyuki; Kaino, Masatomo; Sato, Toshiyuki

2006-01-01

A polycrystalline CdZnTe film formed by the CSS (closed-spaced sublimation) method is one of the most promising materials as a conversion layer of next-generation highly efficient flat-panel X-ray detectors. Therefore, we have developed a prototype of a new flat-panel X-ray detector (a sensing region of 3 inches by 3 inches) with the film and evaluated its commercial feasibility. This paper describes evaluation of the physical and imaging properties of the prototype and explains the features of the CdZnTe film and the construction, specifications, and fabrication procedures of the prototype. Also included in this paper are formation of a semiconductor thin film barrier layer by the CBD (chemical bath deposition) method and conjunction of a sensor substrate and a TFT array substrate with the bump electrodes formed by screen printing, both of which we have developed during the course of the development of the prototype. (author)

An asynchronous, pipelined, electronic acquisition system for Active Matrix Flat-Panel Imagers (AMFPIs)

CERN Document Server

Huang, W; Berry, J; Maolinbay, M; Martelli, C; Mody, P; Nassif, S; Yeakey, M

1999-01-01

The development of a full-custom electronic acquisition system designed for readout of large-area active matrix flat-panel imaging arrays is reported. The arrays, which comprise two-dimensional matrices of pixels utilizing amorphous silicon thin-film transistors, are themselves under development for a wide variety of X-ray imaging applications. The acquisition system was specifically designed to facilitate detailed, quantitative investigations of the properties of these novel imaging arrays and contains significant enhancements compared to a previously developed acquisition system. These enhancements include pipelined preamplifier circuits to allow faster readout speed, expanded addressing capabilities allowing a maximum of 4096 array data lines, and on-board summing of image frames. The values of many acquisition system parameters, including timings and voltages, may be specified and downloaded from a host computer. Once acquisition is enabled, the system operates asynchronously of its host computer. The sys...

FY 1998 annual summary report on comprehensive development study of high-function flat panel display techniques (second year); 1998 nendo koseino flat panel display gijutsu no sogo kaihatsu kenkyu seika hokokusho. Daininendo

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

This project is aimed at creation of the new world display industry in Shikoku by developing the high-function flat panel display techniques and thereby establishing new techniques which solve the problems involved in, e.g., LEDs, plasma-aided devices and ELs other than liquid crystal devices. For development of emitters using diamond, important results have been obtained for the morphology, and cathode luminescence, Raman and photoluminescence spectra of polycrystalline diamond, synthesized by the vapor-phase process under varying conditions, on the electron radiation characteristics of the emitters. These results have led to clarification of the optimum vapor-phase synthesis conditions for diamond for high-function emitters. The techniques utilizing focused ion beams have also advanced to develop thin polycrystalline diamond films for emitters which correspond to the image elements of quality for television. For electron emitters, a structure prepared by implantation without using a high electrical field is proposed, and the device mechanisms involved are clarified. (NEDO)

Implementation of a program of quality assurance of image in an imaging system of flat panel portal; Puesta en marcha de un programa de garantia de calidad de imagen en un sistema de imagen portal de panel plano

Energy Technology Data Exchange (ETDEWEB)

Gomez Barrado, A.; Sanchez Jimenez, E.; Benitez, J. A.; Sanchez-Reyes, A.

2013-07-01

(IGRT) image-guided radiation therapy is the one in which images are used to locate the area of treatment. Modern irradiation systems are equipped with different modalities for obtaining images, such as flat panel systems, systems conebeam, tomoimagen, etc. This paper describes the start-up and the experience of a quality assurance program based on a flat panel portal Imaging System. (Author)

Advances in infrastructure support for flat panel display manufacturing

Science.gov (United States)

Bardsley, James N.; Ciesinski, Michael F.; Pinnel, M. Robert

1997-07-01

The success of the US display industry, both in providing high-performance displays for the US Department of Defense at reasonable cost and in capturing a significant share of the global civilian market, depends on maintaining technological leadership and on building efficient manufacturing capabilities. The US Display Consortium (USDC) was set up in 1993 by the US Government and private industry to guide the development of the infrastructure needed to support the manufacturing of flat panel displays. This mainly involves the supply of equipment and materials, but also includes the formation of partnerships and the training of a skilled labor force. Examples are given of successful development projects, some involving USDC participation, others through independent efforts of its member companies. These examples show that US-based companies can achieve leadership positions in this young and rapidly growing global market.

Critical issues in enhancing brightness in thin film phosphors for flat-panel display applications

International Nuclear Information System (INIS)

Singh, R.K.; Chen, Z.; Kumar, D.; Cho, K.; Ollinger, M.

2002-01-01

Thin film phosphors have potential applications in field emission flat-panel displays. However, they are limited by the lower cathodoluminescent brightness in comparison to phosphor powders. In this paper, we have investigated the critical parameters that need to be optimized to increase the brightness of phosphor thin films. Specifically, we studied the role of surface roughness and optical properties of the substrate on the brightness of the phosphor films. Thin Y 2 O 3 :Eu phosphor films were deposited on various substrates (lanthanum aluminate, quartz, sapphire, and silicon) with thicknesses varying from 50 to 500 nm. A model that accounts for diffuse and specular or scattering effects has been developed to understand the effects of the microstructure on the emission characteristics of the cathodoluminescent films. The results from the model show that both the optical properties of the substrate and the surface roughness of the films play a critical role in controlling the brightness of laser deposited phosphor films

High resolution X-ray imaging of bone-implant interface by large area flat-panel detector

International Nuclear Information System (INIS)

Kytyr, D; Jirousek, O; Dammer, J

2011-01-01

The aim of the research was to investigate the cemented bone-implant interface behavior (cement layer degradation and bone-cement interface debonding) with emphasis on imaging techniques suitable to detect the early defects in the cement layer. To simulate in vivo conditions a human pelvic bone was implanted with polyurethane acetabular cup using commercial acrylic bone cement. The implanted cup was then loaded in a custom hip simulator to initiate fatigue crack propagation in the bone cement. The pelvic bone was then repetitively scanned in a micro-tomography device. Reconstructed tomography images showed failure processes that occurred in the cement layer during the first 250,000 cycles. A failure in cemented acetabular implant - debonding, crumbling and smeared cracks - has been found to be at the bone-cement interface. Use of micro-focus source and high resolution flat panel detector of large physical dimensions allowed to reconstruct the micro-structural models suitable for investigation of migration, micro-motions and consecutive loosening of the implant. The large area flat panel detector with physical dimensions 120 x 120mm with 50μm pixel size provided a superior image quality compared to clinical CT systems with 300-150μm pixel size.

Use and imaging performance of CMOS flat panel imager with LiF/ZnS(Ag) and Gadox scintillation screens for neutron radiography

Science.gov (United States)

Cha, B. K.; kim, J. Y.; Kim, T. J.; Sim, C.; Cho, G.; Lee, D. H.; Seo, C.-W.; Jeon, S.; Huh, Y.

2011-01-01

In digital neutron radiography system, a thermal neutron imaging detector based on neutron-sensitive scintillating screens with CMOS(complementary metal oxide semiconductor) flat panel imager is introduced for non-destructive testing (NDT) application. Recently, large area CMOS APS (active-pixel sensor) in conjunction with scintillation films has been widely used in many digital X-ray imaging applications. Instead of typical imaging detectors such as image plates, cooled-CCD cameras and amorphous silicon flat panel detectors in combination with scintillation screens, we tried to apply a scintillator-based CMOS APS to neutron imaging detection systems for high resolution neutron radiography. In this work, two major Gd2O2S:Tb and 6LiF/ZnS:Ag scintillation screens with various thickness were fabricated by a screen printing method. These neutron converter screens consist of a dispersion of Gd2O2S:Tb and 6LiF/ZnS:Ag scintillating particles in acrylic binder. These scintillating screens coupled-CMOS flat panel imager with 25x50mm2 active area and 48μm pixel pitch was used for neutron radiography. Thermal neutron flux with 6x106n/cm2/s was utilized at the NRF facility of HANARO in KAERI. The neutron imaging characterization of the used detector was investigated in terms of relative light output, linearity and spatial resolution in detail. The experimental results of scintillating screen-based CMOS flat panel detectors demonstrate possibility of high sensitive and high spatial resolution imaging in neutron radiography system.

Standard practice for radiologic examination of flat panel composites and sandwich core materials used in aerospace applications

CERN Document Server

American Society for Testing and Materials. Philadelphia

2009-01-01

1.1 This practice is intended to be used as a supplement to Practices E 1742, E 1255, and E 2033. 1.2 This practice describes procedures for radiologic examination of flat panel composites and sandwich core materials made entirely or in part from fiber-reinforced polymer matrix composites. Radiologic examination is: a) radiographic (RT) with film, b) Computed Radiography (CR) with Imaging Plate, c) Digital Radiology (DR) with Digital Detector Array’s (DDA), and d) Radioscopic (RTR) Real Time Radiology with a detection system such as an Image Intensifier. The composite materials under consideration typically contain continuous high modulus fibers (> 20 GPa), such as those listed in 1.4. 1.3 This practice describes established radiological examination methods that are currently used by industry that have demonstrated utility in quality assurance of flat panel composites and sandwich core materials during product process design and optimization, process control, after manufacture inspection, in service exami...

Flat connection, conformal field theory and quantum group

International Nuclear Information System (INIS)

Kato, Mitsuhiro.

1989-07-01

General framework of linear first order differential equation for four-point conformal block is studied by using flat connection. Integrability and SL 2 invariance restrict possible form of flat connection. Under a special ansatz classical Yang-Baxter equation appears as an integrability condition and the WZW model turns to be unique conformal field theory in that case. Monodromy property of conformal block can be easily determined by the flat connection. 11 refs

A camac based data acquisition system for flat-panel image array readout

International Nuclear Information System (INIS)

Morton, E.J.; Antonuk, L.E.; Berry, J.E.; Huang, W.; Mody, P.; Yorkston, J.; Longo, M.J.

1993-01-01

A readout system has been developed to facilitate the digitization and subsequent display of image data from two-dimensional, pixellated, flat-panel, amorphous silicon imaging arrays. These arrays have been designed specifically for medical x-ray imaging applications. The readout system is based on hardware and software developed for various experiments at CERN and Fermi National Accelerator Laboratory. Additional analog signal processing and digital control electronics were constructed specifically for this application. The authors report on the form of the resulting data acquisition system, discuss aspects of its performance, and consider the compromises which were involved in its design

Report of the results of the fiscal 1997 regional consortium R and D project. Regional consortium energy field/R and D high performance flat panel display technology (first fiscal year); 1997 nendo chiiki consortium kenkyu kaihatsu jigyo. Chiiki consortium energy bun`ya / koseino flat panel display gijutsu no sogo kaihatsu kenkyu (daiichi nendo ) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

One of the subjects in technology supporting the highly information-oriented society which will develop and diversify toward the 21st century is the construction of high grade man/machine interface. For it, high precision/high luminance/energy saving/thin plane displays are strongly requested. This R and D is to indicate models of systematical development in the region of element technology individually existing in the Shikoku area by forming a regional consortium in the industry/universities/government. Creation of new industries by gathering display related enterprises is a first step in a plan to realize `Display Island Shikoku.` As a concrete target, with the use of high-tech diamond semiconducting technology, a development is conducted of the high performance flat panel display using the negative electron affinity (NEA) electron emitter which drastically solves the problems such as luminance, visibility angle and response speed, the subjects on the commercialized liquid crystal flat panel display. 16 refs., 45 figs., 8 tabs.

Initial experiences in clinical application of the THORAX-FD: flat-panel detector radiography in thoracic diagnosis

International Nuclear Information System (INIS)

Herrmann, K.A.; Staebler, A.; Bonel, H.; Kulinna, C.; Holzknecht, N.; Reiser, M.F.; Geiger, B.; Boehm, S.; Maschke, M.

2000-01-01

The flat-panel detector closes the gap between radiography and the digital diagnostics equipment currently in use. In addition to the dose reduction that can be expected, the availability of diagnostic information in digital form enables the user to optimize the clinical workflow and to network radiography directly with a digital archiving and communication system. (orig.)

Modeling on the cathodoluminescence properties of the thin film phosphors for field emission flat panel displays

Science.gov (United States)

Cho, Kyu-Gong

2000-12-01

utilized to optimize the thin film phosphor properties for the application of field emission flat panel displays.

ACS/WFC Sky Flats from Frontier Fields Imaging

Science.gov (United States)

Mack, J.; Lucas, R. A.; Grogin, N. A.; Bohlin, R. C.; Koekemoer, A. M.

2018-04-01

Parallel imaging data from the HST Frontier Fields campaign (Lotz et al. 2017) have been used to compute sky flats for the ACS/WFC detector in order to verify the accuracy of the current set of flat field reference files. By masking sources and then co-adding many deep frames, the F606W and F814W filters have enough combined background signal that from Poisson statistics are efficiency tracks the thickness of the two WFC chips. Observations of blue and red calibration standards measured at various positions on the detector (Bohlin et al. 2017) confirm the fidelity of the F814W flat, with aperture photometry consistent to 1% across the FOV, regardless of spectral type. At bluer wavelengths, the total sky background is substantially lower, and the F435W sky flat shows a combination of both flat errors and detector artifacts. Aperture photometry of the red standard star shows a maximum deviation of 1.4% across the array in this filter. Larger residuals up to 2.5% are found for the blue standard, suggesting that the spatial sensitivity in F435W depends on spectral type.

Flat-panel detectors: how much better are they?

International Nuclear Information System (INIS)

Seibert, J.A.

2006-01-01

Interventional and fluoroscopic imaging procedures for pediatric patients are becoming more prevalent because of the less-invasive nature of these procedures compared to alternatives such as surgery. Flat-panel X-ray detectors (FPD) for fluoroscopy are a new technology alternative to the image intensifier/TV (II/TV) digital system that has been in use for more than two decades. Two major FPD technologies have been implemented, based on indirect conversion of X-rays to light (using an X-ray scintillator) and then to proportional charge (using a photodiode), or direct conversion of X-rays into charge (using a semiconductor material) for signal acquisition and digitization. These detectors have proved very successful for high-exposure interventional procedures but lack the image quality of the II/TV system at the lowest exposure levels common in fluoroscopy. The benefits for FPD image quality include lack of geometric distortion, little or no veiling glare, a uniform response across the field-of-view, and improved ergonomics with better patient access. Better detective quantum efficiency indicates the possibility of reducing the patient dose in accordance with ALARA principles. However, first-generation FPD devices have been implemented with less than adequate acquisition flexibility (e.g., lack of tableside controls/information, inability to easily change protocols) and the presence of residual signals from previous exposures, and additional cost of equipment and long-term maintenance have been serious impediments to purchase and implementation. Technological advances of second generation and future hybrid FPD systems should solve many current issues. The answer to the question ''how much better are they?'' is ''significantly better'', and they are certainly worth consideration for replacement or new implementation of an imaging suite for pediatric fluoroscopy. (orig.)

Evaluation of a flat-panel detector system

International Nuclear Information System (INIS)

Sato, Masami; Eguchi, Yoichi; Yamada, Kinichi; Kaga, Yuji; Endo, Yutaka; Yamazaki, Tatsuya

2001-01-01

We evaluated the imaging performance of a flat-panel detector digital radiography system (CXDI-11 X-ray Digital Camera, Canon Inc.) and a computed radiography system (FCR9000C-HQ, Fuji Film). The characteristics of the two detectors and of the overall systems were compared. This included evaluation and comparison of the fundamental physical characteristics, including x-ray response curve, modulation transfer function (MTF), Wiener spectra, noise-equivalent quanta, and x-ray tube voltage-dependent detector response. Overall system performance was evaluated using receiver operating characteristic (ROC) analysis. The results of the study showed that the dynamic range of the CXDI-11 measured relative to the input x-ray flux was 10 3 , similar to that of the FCR9000C-HQ. Both systems showed similar final MTFs, although the pre-sampling MTF of the CXDI-11 was better than that of the FCR9000C-HQ. Noise analysis, based on noise-equivalent quanta and Wiener spectra, showed that for normal exposure conditions the CXDI-11 had superior performance. With both systems, x-ray response (system output/incident x-ray exposure) increased with increasing x-ray tube voltage. ROC analysis indicated that the CXDI-11 was superior in overall performance. (author)

Variation in X-ray dose quantity using an amorphous selenium based flat-panel detector - a study on the dose reduction rate up to the limit of diagnostical utilization

International Nuclear Information System (INIS)

Lehnert, T.; Wohlers, J.; Manegold, K.; Wetter, A.; Jacobi, V.; Mack, M.G.; Vogl, T.J.; Streng, W.

2006-01-01

Purpose: To evaluate the diagnostic quality and minimum required dose to obtain acceptable images for diagnostic purposes in the field of musculoskeletal radiology. Materials and methods: A critical comparison of the image quality produced by a novel flat panel detector and the conventional screen/film system using a contrast-detail phantom was performed in phase I. Images from both systems were obtained with the same dose and displayed with similar contrast and density. In phase II images of significant anatomical structures in cadaver extremities obtained using the digital detector system and the standard film/screen system were critically evaluated. After a successive reduction in the X-ray dose for 84 patients in phase III, eight independent radiologists compared the image quality of the screen/film system to that of the novel flat panel detector. Results: Phases I and II revealed a difference in the image quality achieved by the standard screen/film system and the digital detector system to the advantage of the digital detector system. In 77 of 84 patients (91.7%), phase III showed equal image quality after a 50% reduction in the X-ray dose. In 3 cases (3.6%) the image quality and the level of contrast were better. No unified statement could be made for 4 patients (4.7%). Conclusion: Digital imaging of skeletal disorders using the novel flat panel detector makes it possible to reduce the X-ray dose by 50% with equal or even better image quality. (orig.)

Review of flat panel display programs and defense applications

Science.gov (United States)

Gnade, Bruce; Schulze, Raymond; Henderson, Girardeau L.; Hopper, Darrel G.

1997-07-01

Flat panel display research has comprised a substantial portion of the national investment in new technology for economic and national security for the past nine years. These investments have ben made principally via several Defense Advanced Research Projects Agency (DARPA) programs, known collectively as the continuing High Definition Systems Program, and the Office of the Secretary of Defense Production Act Title III Program. Using input from the Army, Navy, and Air Force to focus research and identify insertion opportunities, DARPA and the Title III Program Office have made investments to develop the national technology base and manufacturing infrastructure necessary to meet the twin challenge of providing affordable displays in current systems and enabling the DoD strategy of winning future conflicts by getting more information to all participants during the battle. These research programs are reviewed and opportunities for applications are described. Future technology development, transfer, and transition requirements are identified. Strategy and vision are documented to assist the identification of areas meriting further consideration.

Compact flat-panel gas-gap heat switch operating at 295 K

Science.gov (United States)

Krielaart, M. A. R.; Vermeer, C. H.; Vanapalli, S.

2015-11-01

Heat switches are devices that can change from a thermally conducting (on-) state to an insulating (off-) state whenever the need arises. They enable adaptive thermal management strategies in which cooling rates are altered either spatially or temporally, leading to a substantial reduction in the energy and mass budget of a large range of systems. State-of-the-art heat switches are only rarely employed in thermal system architectures, since they are rather bulky and have a limited thermal performance (expressed as the heat transfer ratio between the on- and off-state heat conductance). Using selective laser melting additive manufacturing technology, also known as 3D printing, we developed a compact flat-panel gas-gap heat switch that offers superior thermal performance, is simpler and more economic to produce and assemble, contains no moving parts, and is more reliable because it lacks welded joints. The manufactured rectangular panel heat switch has frontal device dimensions of 10 cm by 10 cm, thickness of 3.2 mm and weighs just 121 g. An off heat conductance of 0.2 W/K and on-off heat conductance ratio of 38 is observed at 295 K.

UVIS Flat Field Uniformity

Science.gov (United States)

Quijano, Jessica Kim

2009-07-01

The stability and uniformity of the low-frequency flat fields {L-flat} of the UVIS detector will be assessed by using multiple-pointing observations of the globular clusters 47 Tucanae {NGC104} and Omega Centauri {NGC5139}, thus imaging moderately dense stellar fields. By placing the same star over different portions of the detector and measuring relative changes in its brightness, it will be possible to determine local variations in the response of the UVIS detector. Based on previous experience with STIS and ACS, it is deemed that a total of 9 different pointings will suffice to provide adequate characterization of the flat field stability in any given band. For each filter to be tested, the baseline consists of 9 pointings in a 3X3 box pattern with dither steps of about 25% of the FOV, or 40.5", in either the x or y direction {useful also for CTE measurements, if needed in the future}. During SMOV, the complement of filters to be tested is limited to the following 6 filters: F225W, F275W, F336W, for Omega Cen, and F438W, F606W, and F814W for 47 Tuc. Three long exposures for each target are arranged such that the initial dither position is observed with the appropriate filters for that target within one orbit at a single pointing, so that filter-to-filter differences in the observed star positions can be checked. In addition to the 9 baseline exposures, two sets of short exposures will be taken:a} one short exposure will be taken of OmegaCen with each of the visible filters {F438W, F606W and F814W} in order to check the geometric distortion solution to be obtained with the data from proposal 11444;b} for each target, a single short exposure will be taken with each filter to facilitate the study of the PSF as a function of position on the detector by providing unsaturated images of sparsely-spaced bright stars.This proposal corresponds to Activity Description ID WF39. It should execute only after the following proposal has executed:WF21 - 11434

SOUND FIELD SHIELDING BY FLAT ELASTIC LAYER AND THIN UNCLOSED SPHERICAL SHELL

Directory of Open Access Journals (Sweden)

G. Ch. Shushkevich

2014-01-01

Full Text Available An analytical solution of a boundary problem describing the process of penetration of a sound field of a spherical radiator located inside a thin unclosed spherical shell through a flat elastic layer is constructed. An influence of some parameters of the problem on the value of the attenuation coeffi-cient (screening of the sound field was studied by using a numerical simulation.

Carbon Nanotube Thin Film Transistors for Flat Panel Display Application.

Science.gov (United States)

Liang, Xuelei; Xia, Jiye; Dong, Guodong; Tian, Boyuan; Peng, Lianmao

2016-12-01

Carbon nanotubes (CNTs) are promising materials for both high performance transistors for high speed computing and thin film transistors for macroelectronics, which can provide more functions at low cost. Among macroelectronics applications, carbon nanotube thin film transistors (CNT-TFT) are expected to be used soon for backplanes in flat panel displays (FPDs) due to their superior performance. In this paper, we review the challenges of CNT-TFT technology for FPD applications. The device performance of state-of-the-art CNT-TFTs are compared with the requirements of TFTs for FPDs. Compatibility of the fabrication processes of CNT-TFTs and current TFT technologies are critically examined. Though CNT-TFT technology is not yet ready for backplane production line of FPDs, the challenges can be overcome by close collaboration between research institutes and FPD manufacturers in the short term.

Potential Applications of Flat-Panel Volumetric CT in Morphologic, Functional Small Animal Imaging

Directory of Open Access Journals (Sweden)

Susanne Greschus

2005-08-01

Full Text Available Noninvasive radiologic imaging has recently gained considerable interest in basic, preclinical research for monitoring disease progression, therapeutic efficacy. In this report, we introduce flat-panel volumetric computed tomography (fpVCT as a powerful new tool for noninvasive imaging of different organ systems in preclinical research. The three-dimensional visualization that is achieved by isotropic high-resolution datasets is illustrated for the skeleton, chest, abdominal organs, brain of mice. The high image quality of chest scans enables the visualization of small lung nodules in an orthotopic lung cancer model, the reliable imaging of therapy side effects such as lung fibrosis. Using contrast-enhanced scans, fpVCT displayed the vascular trees of the brain, liver, kidney down to the subsegmental level. Functional application of fpVCT in dynamic contrast-enhanced scans of the rat brain delivered physiologically reliable data of perfusion, tissue blood volume. Beyond scanning of small animal models as demonstrated here, fpVCT provides the ability to image animals up to the size of primates.

Establishment of action levels for quality control of IMRT flat panel: experience with the algorithm iGRiMLO

International Nuclear Information System (INIS)

Gonzalez, V.; Dolores, VV. de los; Pastor, V.; Martinez, J.; Gimeno, J.; Guardino, C.; Crispin, V.

2011-01-01

Algorithm has been used at our institution iGRiMLO scheduled for individual verification of treatment plans for intensity modulated radiotherapy (IMRT) step and shoot through portal dosimetry pretreatment of non-transmission, triggering the plan directly to a portal imaging device (EPID) of an amorphous silicon flat panel.

Dynamic chest radiography: flat-panel detector (FPD) based functional X-ray imaging.

Science.gov (United States)

Tanaka, Rie

2016-07-01

Dynamic chest radiography is a flat-panel detector (FPD)-based functional X-ray imaging, which is performed as an additional examination in chest radiography. The large field of view (FOV) of FPDs permits real-time observation of the entire lungs and simultaneous right-and-left evaluation of diaphragm kinetics. Most importantly, dynamic chest radiography provides pulmonary ventilation and circulation findings as slight changes in pixel value even without the use of contrast media; the interpretation is challenging and crucial for a better understanding of pulmonary function. The basic concept was proposed in the 1980s; however, it was not realized until the 2010s because of technical limitations. Dynamic FPDs and advanced digital image processing played a key role for clinical application of dynamic chest radiography. Pulmonary ventilation and circulation can be quantified and visualized for the diagnosis of pulmonary diseases. Dynamic chest radiography can be deployed as a simple and rapid means of functional imaging in both routine and emergency medicine. Here, we focus on the evaluation of pulmonary ventilation and circulation. This review article describes the basic mechanism of imaging findings according to pulmonary/circulation physiology, followed by imaging procedures, analysis method, and diagnostic performance of dynamic chest radiography.

Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging

International Nuclear Information System (INIS)

Schmidgunst, C.; Ritter, D.; Lang, E.

2007-01-01

The continuing research and further development in flat panel detector technology have led to its integration into more and more medical x-ray systems for two-dimensional (2D) and three-dimensional (3D) imaging, such as fixed or mobile C arms. Besides the obvious advantages of flat panel detectors, like the slim design and the resulting optimum accessibility to the patient, their success is primarily a product of the image quality that can be achieved. The benefits in the physical and performance-related features as opposed to conventional image intensifier systems (e.g., distortion-free reproduction of imaging information or almost linear signal response over a large dynamic range) can be fully exploited, however, only if the raw detector images are correctly calibrated and postprocessed. Previous procedures for processing raw data contain idealizations that, in the real world, lead to artifacts or losses in image quality. Thus, for example, temperature dependencies or changes in beam geometry, as can occur with mobile C arm systems, have not been taken into account up to this time. Additionally, adverse characteristics such as image lag or aging effects have to be compensated to attain the best possible image quality. In this article a procedure is presented that takes into account the important dependencies of the individual pixel sensitivity of flat panel detectors used in 2D or 3D imaging and simultaneously minimizes the work required for an extensive recalibration. It is suitable for conventional detectors with only one gain mode as well as for the detectors specially developed for 3D imaging with dual gain read-out technology

A true minimally invasive approach for cochlear implantation: high accuracy in cranial base navigation through flat-panel-based volume computed tomography.

Science.gov (United States)

Majdani, Omid; Bartling, Soenke H; Leinung, Martin; Stöver, Timo; Lenarz, Minoo; Dullin, Christian; Lenarz, Thomas

2008-02-01

High-precision intraoperative navigation using high-resolution flat-panel volume computed tomography makes feasible the possibility of minimally invasive cochlear implant surgery, including cochleostomy. Conventional cochlear implant surgery is typically performed via mastoidectomy with facial recess to identify and avoid damage to vital anatomic landmarks. To accomplish this procedure via a minimally invasive approach--without performing mastoidectomy--in a precise fashion, image-guided technology is necessary. With such an approach, surgical time and expertise may be reduced, and hearing preservation may be improved. Flat-panel volume computed tomography was used to scan 4 human temporal bones. A drilling channel was planned preoperatively from the mastoid surface to the round window niche, providing a margin of safety to all functional important structures (e.g., facial nerve, chorda tympani, incus). Postoperatively, computed tomographic imaging and conventional surgical exploration of the drilled route to the cochlea were performed. All 4 specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in 1 specimen--this was preoperatively planned as a narrow facial recess was encountered. Using flat-panel volume computed tomography for image-guided surgical navigation, we were able to perform minimally invasive cochlear implant surgery defined as a narrow, single-channel mastoidotomy with cochleostomy. Although this finding is preliminary, it is technologically achievable.

On site evaluation of three flat panel detectors for digital radiography

International Nuclear Information System (INIS)

Borasi, Giovanni; Nitrosi, Andrea; Ferrari, Paolo; Tassoni, Davide

2003-01-01

During a tender we evaluated the image performance of three commercially available active matrix flat panel imagers (AMFPI) for general radiography, one based on direct detection method (Se photoconductor) the other two on indirect detection method (CsI phosphor). Basic image quality parameters (MTF, NNPS, DQE) were evaluated with particular attention to dose and energy dependence. As it is known, presampling modulation transfer function (MTF) of selenium based detector is very high (at 70 kV, 2 cycles/mm, 2.5 μGy, about 0.80). Indirect detection panels exhibit a comparable (lower) resolution (at 70 kV, 2 cycles/mm, 2.5 μGy, MTF is about 0.34 for both the systems analyzed) and a more pronounced energy and dose dependence could also be noted in one of them. As a consequence of the very high resolution, the normalized noise power spectrum (NNPS) of the direct system is substantially flat, very similar to a white noise. Considering that the sensitive layer of all detectors is the same (0.5 mm), the relatively higher NNPS values are related to selenium absorption properties (lower Z respect to CsI:Tl) and detector inherent noise. NNPSs of the other systems, at low frequencies, are comparable but the frequency dependence is significantly different. At 70 kV, 2.5 μGy, 0.5 cycles/mm detective quantum efficiency (DQE) is about 0.35 for the direct detection system, and about the same (0.6) for the indirect ones. The combined effect of additive and multiplicative noise components makes DQE dependence on dose not monotonic. DQE present a maximum for an intermediate exposure. This complex behavior may be useful to characterize the systems in terms of the monodimensional integral over the frequency of DQE (IDQE). Both visual contrast-detail experiment and the direct evaluation of the signal-to-noise ratio confirmed, at least in a qualitative way, the system performances predicted by IDQE

Field-theoretic approach to gravity in the flat space-time

Energy Technology Data Exchange (ETDEWEB)

Cavalleri, G [Centro Informazioni Studi Esperienze, Milan (Italy); Milan Univ. (Italy). Ist. di Fisica); Spinelli, G [Istituto di Matematica del Politecnico di Milano, Milano (Italy)

1980-01-01

In this paper it is discussed how the field-theoretical approach to gravity starting from the flat space-time is wider than the Einstein approach. The flat approach is able to predict the structure of the observable space as a consequence of the behaviour of the particle proper masses. The field equations are formally equal to Einstein's equations without the cosmological term.

Effect of the Tuner on the Field Flatness of SNS Superconducting RF Cavities

CERN Document Server

Sun, A

2004-01-01

Field flatness in a multi-cell superconducting cavity affects not only the net accelerating voltage, but also the peak surface field and the Lorenz Force detuning coefficient. Our measurement indicates that the field flatness changes both external Q of the Fundamental Power Coupler (FPC) and external Q of the Field Probe (FP). The field amplitude tilts linearly to the distance between the cell center and the cavity’s geometry center (pivot point). The tilt rate has been measured in a cryomodule cold (2 K) test, being about 2%/100 kHz, relative the field flatness at the cavity’s center frequency of 805 MHz. Bead-pull measurements confirmed that the field flatness change is 2.0%/100 kHz for a medium β cavity with helium vessel, and 1.72%/100 kHz without helium vessel. These results matched the predictions of simulations using ANSYS and SUPERFISH. A detailed analysis reveals that longitudinal capacitive gap deformation is the main cause of the frequency change. Field flatness change ...

Radiation exposure to operating staff during rotational flat-panel angiography and C-arm cone beam computed tomography (CT) applications

Energy Technology Data Exchange (ETDEWEB)

Schulz, Boris, E-mail: boris.schell@googlemail.com [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Heidenreich, Ralf, E-mail: ralf.heidenreich@roentgen-consult.de [Röntgen-Consult Company, Schulhausstrasse 37, 79199 Kirchzarten (Germany); Heidenreich, Monika, E-mail: info@roentgen-consult.de [Röntgen-Consult Company, Schulhausstrasse 37, 79199 Kirchzarten (Germany); Eichler, Katrin, E-mail: k.eichler@em.uni-frankfurt.de [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Thalhammer, Axel, E-mail: axel.thalhammer@kgu.de [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Naeem, Naguib Nagy Naguib, E-mail: nagynnn@yahoo.com [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Vogl, Thomas Josef, E-mail: T.Vogl@em.uni-frankfurt.de [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Zangos, Stefan, E-mail: Zangos@em.uni-frankfurt.de [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany)

2012-12-15

Purpose: To evaluate the radiation exposure for operating personel associated with rotational flat-panel angiography and C-arm cone beam CT. Materials and methods: Using a dedicated angiography-suite, 2D and 3D examinations of the liver were performed on a phantom to generate scattered radiation. Exposure was measured with a dosimeter at predefined heights (eye, thyroid, breast, gonads and knee) at the physician's location. Analysis included 3D procedures with a field of view (FOV) of 24 cm × 18 cm (8 s/rotation, 20 s/rotation and 5 s/2 rotations), and 47 cm × 18 cm (16 s/2 rotations) and standard 2D angiography (10 s, FOV 24 cm × 18 cm). Results: Measurements showed the highest radiation dose at the eye and thyroid level. In comparison to 2D-DSA (3.9 μSv eye-exposure), the 3D procedures caused an increased radiation exposure both in standard FOV (8 s/rotation: 28.0 μSv, 20 s/rotation: 79.3 μSv, 5 s/2 rotations: 32.5 μSv) and large FOV (37.6 μSv). Proportional distributions were measured for the residual heights. With the use of lead glass, irradiation of the eye lens was reduced to 0.2 μSv (2D DSA) and 10.6 μSv (3D technique with 20 s/rotation). Conclusion: Rotational flat-panel angiography and C-arm cone beam applications significantly increase radiation exposure to the attending operator in comparison to 2D angiography. Our study indicates that the physician should wear protective devices and leave the examination room when performing 3D examinations.

Radiation exposure to operating staff during rotational flat-panel angiography and C-arm cone beam computed tomography (CT) applications.

Science.gov (United States)

Schulz, Boris; Heidenreich, Ralf; Heidenreich, Monika; Eichler, Katrin; Thalhammer, Axel; Naeem, Naguib Nagy Naguib; Vogl, Thomas Josef; Zangos, Stefan

2012-12-01

To evaluate the radiation exposure for operating personnel associated with rotational flat-panel angiography and C-arm cone beam CT. Using a dedicated angiography-suite, 2D and 3D examinations of the liver were performed on a phantom to generate scattered radiation. Exposure was measured with a dosimeter at predefined heights (eye, thyroid, breast, gonads and knee) at the physician's location. Analysis included 3D procedures with a field of view (FOV) of 24 cm × 18 cm (8s/rotation, 20s/rotation and 5s/2 rotations), and 47 cm×18 cm (16s/2 rotations) and standard 2D angiography (10s, FOV 24 cm×18 cm). Measurements showed the highest radiation dose at the eye and thyroid level. In comparison to 2D-DSA (3.9 μSv eye-exposure), the 3D procedures caused an increased radiation exposure both in standard FOV (8s/rotation: 28.0 μSv, 20s/rotation: 79.3 μSv, 5s/2 rotations: 32.5 μSv) and large FOV (37.6 μSv). Proportional distributions were measured for the residual heights. With the use of lead glass, irradiation of the eye lens was reduced to 0.2 μSv (2D DSA) and 10.6 μSv (3D technique with 20s/rotation). Rotational flat-panel angiography and C-arm cone beam applications significantly increase radiation exposure to the attending operator in comparison to 2D angiography. Our study indicates that the physician should wear protective devices and leave the examination room when performing 3D examinations. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Radiation exposure to operating staff during rotational flat-panel angiography and C-arm cone beam computed tomography (CT) applications

International Nuclear Information System (INIS)

Schulz, Boris; Heidenreich, Ralf; Heidenreich, Monika; Eichler, Katrin; Thalhammer, Axel; Naeem, Naguib Nagy Naguib; Vogl, Thomas Josef; Zangos, Stefan

2012-01-01

Purpose: To evaluate the radiation exposure for operating personel associated with rotational flat-panel angiography and C-arm cone beam CT. Materials and methods: Using a dedicated angiography-suite, 2D and 3D examinations of the liver were performed on a phantom to generate scattered radiation. Exposure was measured with a dosimeter at predefined heights (eye, thyroid, breast, gonads and knee) at the physician's location. Analysis included 3D procedures with a field of view (FOV) of 24 cm × 18 cm (8 s/rotation, 20 s/rotation and 5 s/2 rotations), and 47 cm × 18 cm (16 s/2 rotations) and standard 2D angiography (10 s, FOV 24 cm × 18 cm). Results: Measurements showed the highest radiation dose at the eye and thyroid level. In comparison to 2D-DSA (3.9 μSv eye-exposure), the 3D procedures caused an increased radiation exposure both in standard FOV (8 s/rotation: 28.0 μSv, 20 s/rotation: 79.3 μSv, 5 s/2 rotations: 32.5 μSv) and large FOV (37.6 μSv). Proportional distributions were measured for the residual heights. With the use of lead glass, irradiation of the eye lens was reduced to 0.2 μSv (2D DSA) and 10.6 μSv (3D technique with 20 s/rotation). Conclusion: Rotational flat-panel angiography and C-arm cone beam applications significantly increase radiation exposure to the attending operator in comparison to 2D angiography. Our study indicates that the physician should wear protective devices and leave the examination room when performing 3D examinations.

An asynchronous, pipelined, electronic acquisition system for Active Matrix Flat-Panel Imagers (AMFPIs)

Energy Technology Data Exchange (ETDEWEB)

Huang, W.; Antonuk, L.E. E-mail: antonuk@umich.edu; Berry, J.; Maolinbay, M.; Martelli, C.; Mody, P.; Nassif, S.; Yeakey, M

1999-07-11

The development of a full-custom electronic acquisition system designed for readout of large-area active matrix flat-panel imaging arrays is reported. The arrays, which comprise two-dimensional matrices of pixels utilizing amorphous silicon thin-film transistors, are themselves under development for a wide variety of X-ray imaging applications. The acquisition system was specifically designed to facilitate detailed, quantitative investigations of the properties of these novel imaging arrays and contains significant enhancements compared to a previously developed acquisition system. These enhancements include pipelined preamplifier circuits to allow faster readout speed, expanded addressing capabilities allowing a maximum of 4096 array data lines, and on-board summing of image frames. The values of many acquisition system parameters, including timings and voltages, may be specified and downloaded from a host computer. Once acquisition is enabled, the system operates asynchronously of its host computer. The system allows image capture in both radiographic mode (corresponding to the capture of individual X-ray images), and fluoroscopic mode (corresponding to the capture of a continual series of X-ray images). A detailed description of the system architecture and the underlying motivations for the design is reported in this paper. (author)

Performance of a static-anode/flat-panel x-ray fluoroscopy system in a diagnostic strength magnetic field: a truly hybrid x-ray/MR imaging system.

Science.gov (United States)

Fahrig, R; Wen, Z; Ganguly, A; DeCrescenzo, G; Rowlands, J A; Stevens, G M; Saunders, R F; Pelc, N J

2005-06-01

Minimally invasive procedures are increasing in variety and frequency, facilitated by advances in imaging technology. Our hybrid imaging system (GE Apollo flat panel, custom Brand x-ray static anode x-ray tube, GE Lunar high-frequency power supply and 0.5 T Signa SP) provides both x-ray and MR imaging capability to guide complex procedures without requiring motion of the patient between two distant gantries. The performance of the x-ray tube in this closely integrated system was evaluated by modeling and measuring both the response of the filament to an externally applied field and the behavior of the electron beam for field strengths and geometries of interest. The performance of the detector was assessed by measuring the slanted-edge modulation transfer function (MTF) and when placed at zero field and at 0.5 T. Measured resonant frequencies of filaments can be approximated using a modified vibrating beam model, and were at frequencies well below the 25 kHz frequency of our generator for our filament geometry. The amplitude of vibration was not sufficient to cause shorting of the filament during operation within the magnetic field. A simple model of electrons in uniform electric and magnetic fields can be used to estimate the deflection of the electron beam on the anode for the fields of interest between 0.2 and 0.5 T. The MTF measured at the detector and the DQE showed no significant difference inside and outside of the magnetic field. With the proper modifications, an x-ray system can be fully integrated with a MR system, with minimal loss of image quality. Any x-ray tube can be assessed for compatibility when placed at a particular location within the field using the models. We have also concluded that a-Si electronics are robust against magnetic fields. Detailed knowledge of the x-ray system installation is required to provide estimates of system operation.

Performance of a static-anode/flat-panel x-ray fluoroscopy system in a diagnostic strength magnetic field: A truly hybrid x-ray/MR imaging system

International Nuclear Information System (INIS)

Fahrig, R.; Wen, Z.; Ganguly, A.; DeCrescenzo, G.; Rowlands, J.A.; Stevens, G.M.; Saunders, R.F.; Pelc, N.J.

2005-01-01

Minimally invasive procedures are increasing in variety and frequency, facilitated by advances in imaging technology. Our hybrid imaging system (GE Apollo TM flat panel, custom Brand x-ray static anode x-ray tube, GE Lunar high-frequency power supply and 0.5 T Signa SP TM ) provides both x-ray and MR imaging capability to guide complex procedures without requiring motion of the patient between two distant gantries. The performance of the x-ray tube in this closely integrated system was evaluated by modeling and measuring both the response of the filament to an externally applied field and the behavior of the electron beam for field strengths and geometries of interest. The performance of the detector was assessed by measuring the slanted-edge modulation transfer function (MTF) and when placed at zero field and at 0.5 T. Measured resonant frequencies of filaments can be approximated using a modified vibrating beam model, and were at frequencies well below the 25 kHz frequency of our generator for our filament geometry. The amplitude of vibration was not sufficient to cause shorting of the filament during operation within the magnetic field. A simple model of electrons in uniform electric and magnetic fields can be used to estimate the deflection of the electron beam on the anode for the fields of interest between 0.2 and 0.5 T. The MTF measured at the detector and the DQE showed no significant difference inside and outside of the magnetic field. With the proper modifications, an x-ray system can be fully integrated with a MR system, with minimal loss of image quality. Any x-ray tube can be assessed for compatibility when placed at a particular location within the field using the models. We have also concluded that a-Si electronics are robust against magnetic fields. Detailed knowledge of the x-ray system installation is required to provide estimates of system operation

Impact and Penetration of Thin Aluminum 2024 Flat Panels at Oblique Angles of Incidence

Science.gov (United States)

Ruggeri, Charles R.; Revilock, Duane M.; Pereira, J. Michael; Emmerling, William; Queitzsch, Gilbert K., Jr.

2015-01-01

The U.S. Federal Aviation Administration (FAA) and the National Aeronautics and Space Administration (NASA) are actively involved in improving the predictive capabilities of transient finite element computational methods for application to safety issues involving unintended impacts on aircraft and aircraft engine structures. One aspect of this work involves the development of an improved deformation and failure model for metallic materials, known as the Tabulated Johnson-Cook model, or MAT224, which has been implemented in the LS-DYNA commercial transient finite element analysis code (LSTC Corp., Livermore, CA) (Ref. 1). In this model the yield stress is a function of strain, strain rate and temperature and the plastic failure strain is a function of the state of stress, temperature and strain rate. The failure criterion is based on the accumulation of plastic strain in an element. The model also incorporates a regularization scheme to account for the dependency of plastic failure strain on mesh size. For a given material the model requires a significant amount of testing to determine the yield stress and failure strain as a function of the three-dimensional state of stress, strain rate and temperature. In addition, experiments are required to validate the model. Currently the model has been developed for Aluminum 2024 and validated against a series of ballistic impact tests on flat plates of various thicknesses (Refs. 1 to 3). Full development of the model for Titanium 6Al-4V is being completed, and mechanical testing for Inconel 718 has begun. The validation testing for the models involves ballistic impact tests using cylindrical projectiles impacting flat plates at a normal incidence (Ref. 2). By varying the thickness of the plates, different stress states and resulting failure modes are induced, providing a range of conditions over which the model can be validated. The objective of the study reported here was to provide experimental data to evaluate the model

Random source generating far field with elliptical flat-topped beam profile

International Nuclear Information System (INIS)

Zhang, Yongtao; Cai, Yangjian

2014-01-01

Circular and rectangular multi-Gaussian Schell-model (MGSM) sources which generate far fields with circular and rectangular flat-topped beam profiles were introduced just recently (Sahin and Korotkova 2012 Opt. Lett. 37 2970; Korotkova 2014 Opt. Lett. 39 64). In this paper, a random source named an elliptical MGSM source is introduced. An analytical expression for the propagation factor of an elliptical MGSM beam is derived. Furthermore, an analytical propagation formula for an elliptical MGSM beam passing through a stigmatic ABCD optical system is derived, and its propagation properties in free space are studied. It is interesting to find that an elliptical MGSM source generates a far field with an elliptical flat-topped beam profile, being qualitatively different from that of circular and rectangular MGSM sources. The ellipticity and the flatness of the elliptical flat-topped beam profile in the far field are determined by the initial coherence widths and the beam index, respectively. (paper)

Metallic artifacts from internal scaphoid fracture fixation screws: comparison between C-arm flat-panel, cone-beam, and multidetector computed tomography.

Science.gov (United States)

Finkenstaedt, Tim; Morsbach, Fabian; Calcagni, Maurizio; Vich, Magdalena; Pfirrmann, Christian W A; Alkadhi, Hatem; Runge, Val M; Andreisek, Gustav; Guggenberger, Roman

2014-08-01

The aim of this study was to compare image quality and extent of artifacts from scaphoid fracture fixation screws using different computed tomography (CT) modalities and radiation dose protocols. Imaging of 6 cadaveric wrists with artificial scaphoid fractures and different fixation screws was performed in 2 screw positions (45° and 90° orientation in relation to the x/y-axis) using multidetector CT (MDCT) and 2 flat-panel CT modalities, C-arm flat-panel CT (FPCT) and cone-beam CT (CBCT), the latter 2 with low and standard radiation dose protocols. Mean cartilage attenuation and metal artifact-induced absolute Hounsfield unit changes (= artifact extent) were measured. Two independent radiologists evaluated different image quality criteria using a 5-point Likert-scale. Interreader agreements (Cohen κ) were calculated. Mean absolute Hounsfield unit changes and quality ratings were compared using Friedman and Wilcoxon signed-rank tests. Artifact extent was significantly smaller for MDCT and standard-dose FPCT compared with CBCT low- and standard-dose acquisitions (all P 0.05). Both MDCT and FPCT standard-dose protocols showed equal ratings for screw bone interface, fracture line, and trabecular bone evaluation (P = 0.06, 0.2, and 0.2, respectively) and performed significantly better than FPCT low- and CBCT low- and standard-dose acquisitions (all P < 0.05). Good interreader agreement was found for image quality comparisons (Cohen κ = 0.76-0.78). Both MDCT and FPCT standard-dose acquisition showed comparatively less metal-induced artifacts and better overall image quality compared with FPCT low-dose and both CBCT acquisitions. Flat-panel CT may provide sufficient image quality to serve as a versatile CT alternative for postoperative imaging of internally fixated wrist fractures.

Feasibility study of flexible flat-panel X-ray detectors for digital radiography

International Nuclear Information System (INIS)

Joe, Ok La; Yun, Seung Man; Kim, Ho Kyung

2010-01-01

Flexible flat-panel detectors (FPDs), which utilize both organic photodiode (OPD) and organic thin-film transistor (OTFT) technologies, are recently concerned in digital radiography. The flexible FPD has several potential advantages, such as high accessibility to patient, avoidance of geometrical burr due to the oblique angle incidence of X-ray, great reduction in manufacturing cost due to jet-printing. At once, The OPD/OTFT arrays were fabricated by jet-printing techniques, mechanical robustness due to plastic substrates, and so on. In this study, we have investigated the feasibility of flexible FPD by comparing theoretical detective quantum efficiency (DQE) with that of the conventional amorphous silicon-based FPD. We chose copper phthalocyanine-fullerene (CuPc-C60) organic materials for the construction of the flexible FPD. DQE was calculated by the linear-systems transfer theory

Influence of Flat-Panel Fluoroscopic Equipment Variables on Cardiac Radiation Doses

International Nuclear Information System (INIS)

Nickoloff, Edward L.; Lu Zhengfeng; Dutta, Ajoy; So, James; Balter, Stephen; Moses, Jeffrey

2007-01-01

Purpose. To assess the influence of physician-selectable equipment variables on the potential radiation dose reductions during cardiac catheterization examinations using modern imaging equipment. Materials. A modern bi-plane angiography unit with flat-panel image receptors was used. Patients were simulated with 15-30 cm of acrylic plastic. The variables studied were: patient thickness, fluoroscopy pulse rates, record mode frame rates, image receptor field-of-view (FoV), automatic dose control (ADC) mode, SID/SSD geometry setting, automatic collimation, automatic positioning, and others. Results. Patient radiation doses double for every additional 3.5-4.5 cm of soft tissue. The dose is directly related to the imaging frame rate; a decrease from 30 pps to 15 pps reduces the dose by about 50%. The dose is related to [(FoV) -N ] where 2.0 < N < 3.0. Suboptimal positioning of the patient can nearly double the dose. The ADC system provides three selections that can vary the radiation level by 50%. For pediatric studies (2-5 years old), the selection of equipment variables can result in entrance radiation doses that range between 6 and 60 cGy for diagnostic cases and between 15 and 140 cGy for interventional cases. For adult studies, the equipment variables can produce entrance radiation doses that range between 13 and 130 cGy for diagnostic cases and between 30 and 400 cGy for interventional cases. Conclusions. Overall dose reductions of 70-90% can be achieved with pediatric patients and about 90% with adult patients solely through optimal selection of equipment variables

Flat holography: aspects of the dual field theory

Energy Technology Data Exchange (ETDEWEB)

Bagchi, Arjun [Indian Institute of Technology Kanpur,Kalyanpur, Kanpur 208016 (India); Center for Theoretical Physics, Massachusetts Institute of Technology,77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Basu, Rudranil [Saha Institute of Nuclear Physics,Block AF, Sector 1, Bidhannagar, Kolkata 700068 (India); Kakkar, Ashish [Indian Institute of Science Education and Research,Dr Homi Bhabha Road, Pashan, Pune 411008 (India); Mehra, Aditya [Indian Institute of Technology Kanpur,Kalyanpur, Kanpur 208016 (India); Indian Institute of Science Education and Research,Dr Homi Bhabha Road, Pashan, Pune 411008 (India)

2016-12-29

Assuming the existence of a field theory in D dimensions dual to (D+1)-dimensional flat space, governed by the asymptotic symmetries of flat space, we make some preliminary remarks about the properties of this field theory. We review briefly some successes of the 3d bulk – 2d boundary case and then focus on the 4d bulk – 3d boundary example, where the symmetry in question is the infinite dimensional BMS{sub 4} algebra. We look at the constraints imposed by this symmetry on a 3d field theory by constructing highest weight representations of this algebra. We construct two and three point functions of BMS primary fields and surprisingly find that symmetries constrain these correlators to be identical to those of a 2d relativistic conformal field theory. We then go one dimension higher and construct prototypical examples of 4d field theories which are putative duals of 5d Minkowski spacetimes. These field theories are ultra-relativistic limits of electrodynamics and Yang-Mills theories which exhibit invariance under the conformal Carroll group in D=4. We explore the different sectors within these Carrollian gauge theories and investigate the symmetries of the equations of motion to find that an infinite ultra-relativistic conformal structure arises in each case.

Practical expressions describing detective quantum efficiency in flat-panel detectors

Science.gov (United States)

Kim, H. K.

2011-11-01

In radiology, image quality excellence is a balance between system performance and patient dose, hence x-ray systems must be designed to ensure the maximum image quality is obtained for the lowest consistent dose. The concept of detective quantum efficiency (DQE) is widely used to quantify, understand, measure, and predict the performance of x-ray detectors and imaging systems. Cascaded linear-systems theory can be used to estimate DQE based on the system design parameters and this theoretical DQE can be utilized for determining the impact of various physical processes, such as secondary quantum sinks, noise aliasing, reabsorption noise, and others. However, the prediction of DQE usually requires tremendous efforts to determine each parameter consisting of the cascaded linear-systems model. In this paper, practical DQE formalisms assessing both the photoconductor- and scintillator-based flat-panel detectors under quantum-noise-limited operation are described. The developed formalisms are experimentally validated and discussed for their limits. The formalisms described in this paper would be helpful for the rapid prediction of the DQE performances of developing systems as well as the optimal design of systems.

Evaluation of imaging quality for flat-panel detector based low dose C-arm CT system

International Nuclear Information System (INIS)

Seo, Chang-Woo; Cha, Bo Kyung; Jeon, Sungchae; Huh, Young

2015-01-01

The image quality associated with the extent of the angle of gantry rotation, the number of projection views, and the dose of X-ray radiation was investigated in flat-panel detector (FPD) based C-arm cone-beam computed tomography (CBCT) system for medical applications. A prototype CBCT system for the projection acquisition used the X-ray tube (A-132, Varian inc.) having rhenium-tungsten molybdenum target and flat panel a-Si X-ray detector (PaxScan 4030CB, Varian inc.) having a 397 x 298 mm active area with 388 μm pixel pitch and 1024 x 768 pixels in 2 by 2 binning mode. The performance comparison of X-ray imaging quality was carried out using the Feldkamp, Davis, and Kress (FDK) reconstruction algorithm between different conditions of projection acquisition. In this work, head-and-dental (75 kVp/20 mA) and chest (90 kVp/25 mA) phantoms were used to evaluate the image quality. The 361 (30 fps x 12 s) projection data during 360 deg. gantry rotation with 1 deg. interval for the 3D reconstruction were acquired. Parke weighting function were applied to handle redundant data and improve the reconstructed image quality in a mobile C-arm system with limited rotation angles. The reconstructed 3D images were investigated for comparison of qualitative image quality in terms of scan protocols (projection views, rotation angles and exposure dose). Furthermore, the performance evaluation in image quality will be investigated regarding X-ray dose and limited projection data for a FPD based mobile C-arm CBCT system. (authors)

Leaf trajectory verification during dynamic intensity modulated radiotherapy using an amorphous silicon flat panel imager

International Nuclear Information System (INIS)

Sonke, Jan-Jakob; Ploeger, Lennert S.; Brand, Bob; Smitsmans, Monique H.P.; Herk, Marcel van

2004-01-01

An independent verification of the leaf trajectories during each treatment fraction improves the safety of IMRT delivery. In order to verify dynamic IMRT with an electronic portal imaging device (EPID), the EPID response should be accurate and fast such that the effect of motion blurring on the detected moving field edge position is limited. In the past, it was shown that the errors in the detected position of a moving field edge determined by a scanning liquid-filled ionization chamber (SLIC) EPID are negligible in clinical practice. Furthermore, a method for leaf trajectory verification during dynamic IMRT was successfully applied using such an EPID. EPIDs based on amorphous silicon (a-Si) arrays are now widely available. Such a-Si flat panel imagers (FPIs) produce portal images with superior image quality compared to other portal imaging systems, but they have not yet been used for leaf trajectory verification during dynamic IMRT. The aim of this study is to quantify the effect of motion distortion and motion blurring on the detection accuracy of a moving field edge for an Elekta iViewGT a-Si FPI and to investigate its applicability for the leaf trajectory verification during dynamic IMRT. We found that the detection error for a moving field edge to be smaller than 0.025 cm at a speed of 0.8 cm/s. Hence, the effect of motion blurring on the detection accuracy of a moving field edge is negligible in clinical practice. Furthermore, the a-Si FPI was successfully applied for the verification of dynamic IMRT. The verification method revealed a delay in the control system of the experimental DMLC that was also found using a SLIC EPID, resulting in leaf positional errors of 0.7 cm at a leaf speed of 0.8 cm/s

Extra-oral dental radiography for disaster victims using a flat panel X-ray detector and a hand-held X-ray generator.

Science.gov (United States)

Ohtani, M; Oshima, T; Mimasaka, S

2017-12-01

Forensic odontologists commonly incise the skin for post-mortem dental examinations when it is difficult to open the victim's mouth. However, it is prohibited by law to incise dead bodies without permission in Japan. Therefore, we attempted using extra-oral dental radiography, using a digital X-ray equipment with rechargeable batteries, to overcome this restriction. A phantom was placed in the prone position on a table, and three plain dental radiographs were used per case: "lateral oblique radiographs" for left and right posterior teeth and a "contact radiograph" for anterior teeth were taken using a flat panel X-ray detector and a hand-held X-ray generator. The resolving power of the images was measured by a resolution test chart, and the scattered X-ray dose was measured using an ionization chamber-type survey meter. The resolving power of the flat panel X-ray detector was 3.0 lp/mm, which was less than that of intra-oral dental methods, but the three extra-oral plain dental radiographs provided the overall dental information from outside of the mouth, and this approach was less time-consuming. In addition, the higher dose of scattered X-rays was laterally distributed, but the dose per case was much less than that of intra-oral dental radiographs. Extra-oral plain dental radiography can be used for disaster victim identification by dental methods even when it is difficult to open the mouth. Portable and rechargeable devices, such as a flat panel X-ray detector and a hand-held X-ray generator, are convenient to bring and use anywhere, even at a disaster scene lacking electricity and water.

Studies of the performance of different front-end systems for flat-panel multi-anode PMTs with CsI(Tl) scintillator arrays

International Nuclear Information System (INIS)

Sekiya, H.; Hattori, K.; Kubo, H.; Miuchi, K.; Nagayoshi, T.; Nishimura, H.; Okada, Y.; Orito, R.; Takada, A.; Takeda, A.; Tanimori, T.; Ueno, K.

2006-01-01

We have studied the performance of two different types of front-end systems for our gamma camera based on Hamamatsu H8500 (flat-panel 64 channels multi-anode PSPMT) with a CsI(Tl) scintillator array. The array consists of 64 pixels of 6x6x20mm 3 which corresponds to the anode pixels of H8500. One of the system is based on commercial ASIC chips in order to read out every anode. The others are based on resistive charge divider network between anodes to reduce readout channels. In both systems, each pixel (6mm) was clearly resolved by flood field irradiation of 137 Cs. We also investigated the energy resolution of these systems and showed the performance of the cascade connection of resistive network between some PMTs for large area detectors

Dynamic Modeling of the Microalgae Cultivation Phase for Energy Production in Open Raceway Ponds and Flat Panel Photobioreactors

Energy Technology Data Exchange (ETDEWEB)

Marsullo, Matteo [Department of Industrial Engineering, University of Padova, Padova (Italy); Mian, Alberto [Industrial Process and Energy System Engineering Group (IPESE), École Polytechnique Fédérale de Lausanne, Lausanne (Switzerland); Ensinas, Adriano Viana [Industrial Process and Energy System Engineering Group (IPESE), École Polytechnique Fédérale de Lausanne, Lausanne (Switzerland); Universidade Federal do ABC, Santo Andre (Brazil); Manente, Giovanni; Lazzaretto, Andrea, E-mail: andrea.lazzaretto@unipd.it [Department of Industrial Engineering, University of Padova, Padova (Italy); Marechal, François [Industrial Process and Energy System Engineering Group (IPESE), École Polytechnique Fédérale de Lausanne, Lausanne (Switzerland)

2015-09-15

A dynamic model of microalgae cultivation phase is presented in this work. Two cultivation technologies are taken into account: the open raceway pond and the flat panel photobioreactor. For each technology, the model is able to evaluate the microalgae areal and volumetric productivity and the energy production and consumption. Differently from the most common existing models in literature, which deal with a specific part of the overall cultivation process, the model presented here includes all physical and chemical quantities that mostly affect microalgae growth: the equation of the specific growth rate for the microalgae is influenced by CO{sub 2} and nutrients concentration in the water, light intensity, temperature of the water in the reactor, and by the microalgae species being considered. All these input parameters can be tuned to obtain reliable predictions. A comparison with experimental data taken from the literature shows that the predictions are consistent and slightly overestimating the productivity in the case of closed photobioreactor. The results obtained by the simulation runs are consistent with those found in literature, being the areal productivity for the open raceway pond between 50 and 70 t/(ha × year) in Southern Spain (Sevilla) and Brazil (Petrolina) and between 250 and 350 t/(ha × year) for the flat panel photobioreactor in the same locations.

Flat or curved thin optical display panel

Science.gov (United States)

Veligdan, J.T.

1995-01-10

An optical panel includes a plurality of waveguides stacked together, with each waveguide having a first end and an opposite second end. The first ends collectively define a first face, and the second ends collectively define a second face of the panel. The second face is disposed at an acute face angle relative to the waveguides to provide a panel which is relatively thin compared to the height of the second face. In an exemplary embodiment for use in a projection TV, the first face is substantially smaller in height than the second face and receives a TV image, with the second face defining a screen for viewing the image enlarged. 7 figures.

Performance quantification of a flat-panel imager in industrial mega-voltage X-ray imaging systems

Energy Technology Data Exchange (ETDEWEB)

Stritt, Carina, E-mail: carina.stritt@empa.ch [Empa, Swiss Federal Laboratories for Material Science and Technology, Center for X-ray Analytics, Ueberlandstrasse 129, 8600 Dübendorf (Switzerland); Plamondon, Mathieu; Hofmann, Jürgen; Flisch, Alexander [Empa, Swiss Federal Laboratories for Material Science and Technology, Center for X-ray Analytics, Ueberlandstrasse 129, 8600 Dübendorf (Switzerland); Sennhauser, Urs [Empa, Swiss Federal Laboratories for Material Science and Technology, Reliability Science and Technology Laboratory, Ueberlandstrasse 129, 8600 Dübendorf (Switzerland)

2017-03-11

Active matrix flat-panel detectors have gained popularity amongst X-ray imaging systems due to their speed, resolution and high dynamic range. With appropriate shielding modern flat-panel imagers can even be used in high energy Computed Tomography (CT) systems of energies up to several mega-electronvolt (MeV). However, the performance of a digital detector is not independent of the rest of the radiographic system but depends on all other components of the system. Signal and noise transfer properties highly depend on all parameters of an imaging chain. This work focuses on quantifying the resolution capabilities and the noise in the signals of a MeV X-ray imaging system. The performance quantification is done by computing the modulation transfer function (MTF) using the standard edge method as well as the noise power spectrum (NPS) of the imaging system. We performed Monte Carlo (MC) simulations in order to understand the influence of scattered radiation on the measurements. A comparison of the horizontal and vertical MTF showed that the imaging behaviour of the detector is isotropic. Moreover, an additional investigation of the noise performance of the system showed that there is no measurable noise correlation present in the system. It was shown that the thickness of the edge device does not have a significant influence on the resulting system MTF. A rapid drop in the visibility could be observed resulting in a value of 1.2 line pairs per mm at 50% MTF. The visibility limit of line pair patterns was found to be at 2.3 line pairs per mm given by the 10% MTF value.

Performance quantification of a flat-panel imager in industrial mega-voltage X-ray imaging systems

International Nuclear Information System (INIS)

Stritt, Carina; Plamondon, Mathieu; Hofmann, Jürgen; Flisch, Alexander; Sennhauser, Urs

2017-01-01

Active matrix flat-panel detectors have gained popularity amongst X-ray imaging systems due to their speed, resolution and high dynamic range. With appropriate shielding modern flat-panel imagers can even be used in high energy Computed Tomography (CT) systems of energies up to several mega-electronvolt (MeV). However, the performance of a digital detector is not independent of the rest of the radiographic system but depends on all other components of the system. Signal and noise transfer properties highly depend on all parameters of an imaging chain. This work focuses on quantifying the resolution capabilities and the noise in the signals of a MeV X-ray imaging system. The performance quantification is done by computing the modulation transfer function (MTF) using the standard edge method as well as the noise power spectrum (NPS) of the imaging system. We performed Monte Carlo (MC) simulations in order to understand the influence of scattered radiation on the measurements. A comparison of the horizontal and vertical MTF showed that the imaging behaviour of the detector is isotropic. Moreover, an additional investigation of the noise performance of the system showed that there is no measurable noise correlation present in the system. It was shown that the thickness of the edge device does not have a significant influence on the resulting system MTF. A rapid drop in the visibility could be observed resulting in a value of 1.2 line pairs per mm at 50% MTF. The visibility limit of line pair patterns was found to be at 2.3 line pairs per mm given by the 10% MTF value.

New holographic scalar field models of dark energy in non-flat universe

Energy Technology Data Exchange (ETDEWEB)

Karami, K., E-mail: KKarami@uok.ac.i [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Fehri, J. [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of)

2010-02-08

Motivated by the work of Granda and Oliveros [L.N. Granda, A. Oliveros, Phys. Lett. B 671 (2009) 199], we generalize their work to the non-flat case. We study the correspondence between the quintessence, tachyon, K-essence and dilaton scalar field models with the new holographic dark energy model in the non-flat FRW universe. We reconstruct the potentials and the dynamics for these scalar field models, which describe accelerated expansion of the universe. In the limiting case of a flat universe, i.e. k=0, all results given in [L.N. Granda, A. Oliveros, Phys. Lett. B 671 (2009) 199] are obtained.

New holographic scalar field models of dark energy in non-flat universe

International Nuclear Information System (INIS)

Karami, K.; Fehri, J.

2010-01-01

Motivated by the work of Granda and Oliveros [L.N. Granda, A. Oliveros, Phys. Lett. B 671 (2009) 199], we generalize their work to the non-flat case. We study the correspondence between the quintessence, tachyon, K-essence and dilaton scalar field models with the new holographic dark energy model in the non-flat FRW universe. We reconstruct the potentials and the dynamics for these scalar field models, which describe accelerated expansion of the universe. In the limiting case of a flat universe, i.e. k=0, all results given in [L.N. Granda, A. Oliveros, Phys. Lett. B 671 (2009) 199] are obtained.

Cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS flat panel detector: Visibility of simulated microcalcifications

OpenAIRE

Shen, Youtao; Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C.

2013-01-01

Purpose: To measure and investigate the improvement of microcalcification (MC) visibility in cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS/CsI flat panel detector (Dexela 2923, Perkin Elmer).

Robot arm based flat panel CT-guided electromagnetic tracked spine interventions: phantom and animal model experiments

Energy Technology Data Exchange (ETDEWEB)

Penzkofer, Tobias; Isfort, Peter; Bruners, Philipp; Mahnken, Andreas H. [RWTH Aachen University, Applied Medical Engineering, Helmholtz-Institute Aachen, Aachen (Germany); RWTH Aachen University, Department of Diagnostic Radiology, Aachen University Hospital, Aachen (Germany); Wiemann, Christian; Guenther, Rolf W. [RWTH Aachen University, Department of Diagnostic Radiology, Aachen University Hospital, Aachen (Germany); Kyriakou, Yiannis; Kalender, Willi A. [Friedrich-Alexander University of Erlangen-Nuremberg, Institute for Medical Physics, Erlangen (Germany); Schmitz-Rode, Thomas [RWTH Aachen University, Applied Medical Engineering, Helmholtz-Institute Aachen, Aachen (Germany)

2010-11-15

To evaluate accuracy and procedure times of electromagnetic tracking (EMT) in a robotic arm mounted flat panel setting using phantom and animal cadaveric models. A robotic arm mounted flat panel (RMFP) was used in combination with EMT to perform anthropomorphic phantom (n = 90) and ex vivo pig based punctures (n = 120) of lumbar facet joints (FJ, n = 120) and intervertebral discs (IVD, n = 90). Procedure accuracies and times were assessed and evaluated. FJ punctures were carried out with a spatial accuracy of 0.8 {+-} 0.9 mm (phantom) and 0.6 {+-} 0.8 mm (ex vivo) respectively. While IVD punctures showed puncture deviations of 0.6 {+-} 1.2 mm (phantom) and 0.5 {+-} 0.6 mm (ex vivo), direct and angulated phantom based punctures had accuracies of 0.8 {+-} 0.9 mm and 1.0 {+-} 1.3 mm. Planning took longer for ex vivo IVD punctures compared to phantom model interventions (39.3 {+-} 17.3 s vs. 20.8 {+-} 5.0 s, p = 0.001) and for angulated vs. direct phantom FJ punctures (19.7 {+-} 5.1 s vs. 28.6 {+-} 7.8 s, p < 0.001). Puncture times were longer for ex vivo procedures when compared to phantom model procedures in both FJ (37.9 {+-} 9.0 s vs. 23.6 {+-} 7.2 s, p = 0.001) and IVD punctures (43.9 {+-} 16.1 s vs. 31.1 {+-} 6.4 s, p = 0.026). The combination of RMFP with EMT provides an accurate method of navigation for spinal interventions such as facet joint punctures and intervertebral disc punctures. (orig.)

A performance comparison of direct- and indirect-detection flat-panel imagers

CERN Document Server

Partridge, M; Müller, L

2002-01-01

A comparison of the performance of a direct- and an indirect-detection amorphous silicon flat-panel X-ray imager is presented for a 6 MV beam. Experimental measurements of the noise characteristics, image lag, spectral response, spatial resolution and quantum efficiency are described, compared and discussed. The two systems are comprised of 512x512 pixel, 400 mu m pitch, arrays of a-Si:H p-i-n photodiodes and thin-film transistors. In the direct-detection system, X-rays interact to produce electron/hole pairs directly in the silicon photodiodes. For the indirect-detection system, a phosphor screen converts energy from the incident X-rays into visible light, which is then detected by the photodiodes. Both systems are shown to be quantum noise limited, with the total electronic noise in the detector 10-15 times smaller than the Poisson noise level in detected signal. The measured lag for both systems is 1.0+-0.1% or less in the first frame with subsequent signals decaying exponentially with frame read-out, with...

Digital chest radiography: flat-panel detectors or conventional radiographs

International Nuclear Information System (INIS)

Schaefer-Prokop, C.; Uffmann, M.; Sailer, J.; Kabalan, N.; Herold, C.; Prokop, M.

2003-01-01

Flat panel detectors are characterized by improved handling and increased dose efficiency. This allows for increasing of work flow efficiency and for reducing the exposure dose by about 50% compared to current systems with a sensitivity of 400. Whether the increased dose efficiency should be used to reduce acquisition dose or to increase image quality in the chest, will be shown by further clinical experience and will be also determined by the subjective preference of the radiologists. The decreased level of image noise opens new perspectives for image processing that way that elaborated multifrequency processing allows for optimizing the display of very small and low contrast structures that was so far limited by overlying image noise. Specialized applications of dual energy subtraction and temporal subtraction will also profit by the new detector technology and will be further driven forward in context with applications such as computed assisted diagnosis even though this is currently not yet broadly applied. Storage phosphor radiography still represents an important alternative technique based on its larger flexibility with respect to equipment configuration, its broader application options in intensive care and emergency radiology and due to economic reasons. These facts are further underlined by the fact that image quality also in storage phosphor radiography could be constantly increased by improving detector technology and image processing and consequently has a high standard. (orig.) [de

Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality

Science.gov (United States)

Vano, E.; Geiger, B.; Schreiner, A.; Back, C.; Beissel, J.

2005-12-01

The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 µGy/frame (cine) and 5 and 95 mGy min-1 (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality.

Preliminary evaluation of a prototype stereoscopic a-Si:H-based X-ray imaging system for full-field digital mammography

International Nuclear Information System (INIS)

Darambara, D.G.; Speller, R.D.; Horrocks, J.A.; Godber, S.; Wilson, R.; Hanby, A.

2001-01-01

In a pre-clinical study, we have been investigating the potential of a-Si:H active matrix, flat panel imagers for X-ray full-field digital mammography through the development of an advanced 3D X-ray imaging system and have measured a number of their important imaging characteristics. To enhance the information embodied into the digital images produced by the a-Si array, stereoscopic images, created by viewing the object under examination from two angles and recombining the images, were obtained. This method provided us with a full 3D X-ray image of the test object as well as left and right perspective 2D images all at the same time. Within this scope, images of fresh, small human breast tissue specimens--normal and diseased--were obtained at ±2 deg., processed and stereoscopically displayed for a pre-clinical evaluation by radiologists. It was demonstrated that the stereoscopic presentation of the images provides important additional information and has potential benefits over the more traditional 2D data

The effect of oblique angle of sound incidence, realistic edge conditions, curvature and in-plane panel stresses on the noise reduction characteristics of general aviation type panels

Science.gov (United States)

Grosveld, F.; Lameris, J.; Dunn, D.

1979-01-01

Experiments and a theoretical analysis were conducted to predict the noise reduction of inclined and curved panels. These predictions are compared to the experimental results with reasonable agreement between theory and experiment for panels under an oblique angle of sound incidence. Theoretical as well as experimental results indicate a big increase in noise reduction when a flat test panel is curved. Further curving the panel slightly decreases the noise reduction. Riveted flat panels are shown to give a higher noise reduction in the stiffness-controlled frequency region, while bonded panels are superior in this region when the test panel is curved. Experimentally measured noise reduction characteristics of flat aluminum panels with uniaxial in-plane stresses are presented and discussed. These test results indicate an important improvement in the noise reduction of these panels in the frequency range below the fundamental panel/cavity frequency.

Robot arm based flat panel CT-guided electromagnetic tracked spine interventions: phantom and animal model experiments

International Nuclear Information System (INIS)

Penzkofer, Tobias; Isfort, Peter; Bruners, Philipp; Mahnken, Andreas H.; Wiemann, Christian; Guenther, Rolf W.; Kyriakou, Yiannis; Kalender, Willi A.; Schmitz-Rode, Thomas

2010-01-01

To evaluate accuracy and procedure times of electromagnetic tracking (EMT) in a robotic arm mounted flat panel setting using phantom and animal cadaveric models. A robotic arm mounted flat panel (RMFP) was used in combination with EMT to perform anthropomorphic phantom (n = 90) and ex vivo pig based punctures (n = 120) of lumbar facet joints (FJ, n = 120) and intervertebral discs (IVD, n = 90). Procedure accuracies and times were assessed and evaluated. FJ punctures were carried out with a spatial accuracy of 0.8 ± 0.9 mm (phantom) and 0.6 ± 0.8 mm (ex vivo) respectively. While IVD punctures showed puncture deviations of 0.6 ± 1.2 mm (phantom) and 0.5 ± 0.6 mm (ex vivo), direct and angulated phantom based punctures had accuracies of 0.8 ± 0.9 mm and 1.0 ± 1.3 mm. Planning took longer for ex vivo IVD punctures compared to phantom model interventions (39.3 ± 17.3 s vs. 20.8 ± 5.0 s, p = 0.001) and for angulated vs. direct phantom FJ punctures (19.7 ± 5.1 s vs. 28.6 ± 7.8 s, p < 0.001). Puncture times were longer for ex vivo procedures when compared to phantom model procedures in both FJ (37.9 ± 9.0 s vs. 23.6 ± 7.2 s, p = 0.001) and IVD punctures (43.9 ± 16.1 s vs. 31.1 ± 6.4 s, p = 0.026). The combination of RMFP with EMT provides an accurate method of navigation for spinal interventions such as facet joint punctures and intervertebral disc punctures. (orig.)

Transparent Fingerprint Sensor System for Large Flat Panel Display

Directory of Open Access Journals (Sweden)

Wonkuk Seo

2018-01-01

Full Text Available In this paper, we introduce a transparent fingerprint sensing system using a thin film transistor (TFT sensor panel, based on a self-capacitive sensing scheme. An armorphousindium gallium zinc oxide (a-IGZO TFT sensor array and associated custom Read-Out IC (ROIC are implemented for the system. The sensor panel has a 200 × 200 pixel array and each pixel size is as small as 50 μm × 50 μm. The ROIC uses only eight analog front-end (AFE amplifier stages along with a successive approximation analog-to-digital converter (SAR ADC. To get the fingerprint image data from the sensor array, the ROIC senses a capacitance, which is formed by a cover glass material between a human finger and an electrode of each pixel of the sensor array. Three methods are reviewed for estimating the self-capacitance. The measurement result demonstrates that the transparent fingerprint sensor system has an ability to differentiate a human finger’s ridges and valleys through the fingerprint sensor array.

Preliminary performance of image quality for a low-dose C-arm CT system with a flat-panel detector

Energy Technology Data Exchange (ETDEWEB)

Kyung Cha, Bo [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Seo, Chang-Woo [Department of Radiation Convergence Engineering, College of Health Science, Yonsei University, Wonju (Korea, Republic of); Yang, Keedong [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Jeon, Seongchae, E-mail: sarim@keri.re.kr [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Huh, Young [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of)

2015-06-01

Digital flat panel imager (FPI)-based cone-beam computed tomography (CBCT) has been widely used in C-arm imaging for spine surgery and interventional procedures. The system provides real-time fluoroscopy with high spatial resolution and three-dimensional (3D) visualization of anatomical structure without the need for patient transportation in interventional suite. In this work, a prototype CBCT imaging platform with continuous single rotation about the gantry was developed by using a large-area flat-panel detector with amorphous Si-based thin film transistor matrix. The different 2D projection images were acquired during constant gantry velocity for reconstructed images at a tube voltage of 80–120 kVp, and different current (10–50 mA) conditions. Various scan protocols were applied to a chest phantom human by changing the number of projection images and scanning angles. The projections were then reconstructed into a volumetric data of sections by using a 3D reconstruction algorithm (e.g., filtered back projection). The preliminary quantitative X-ray performance of our CBCT system was investigated by using the American Association of Physicists in Medicine CT phantom in terms of spatial resolution, contrast resolution, and CT number linearity for mobile or fixed C-arm based CBCT application with limited rotational geometry. The novel results of the projection data with different scanning angles and angular increments in the orbital gantry platform were acquired and evaluated experimentally.

Preliminary performance of image quality for a low-dose C-arm CT system with a flat-panel detector

International Nuclear Information System (INIS)

Kyung Cha, Bo; Seo, Chang-Woo; Yang, Keedong; Jeon, Seongchae; Huh, Young

2015-01-01

Digital flat panel imager (FPI)-based cone-beam computed tomography (CBCT) has been widely used in C-arm imaging for spine surgery and interventional procedures. The system provides real-time fluoroscopy with high spatial resolution and three-dimensional (3D) visualization of anatomical structure without the need for patient transportation in interventional suite. In this work, a prototype CBCT imaging platform with continuous single rotation about the gantry was developed by using a large-area flat-panel detector with amorphous Si-based thin film transistor matrix. The different 2D projection images were acquired during constant gantry velocity for reconstructed images at a tube voltage of 80–120 kVp, and different current (10–50 mA) conditions. Various scan protocols were applied to a chest phantom human by changing the number of projection images and scanning angles. The projections were then reconstructed into a volumetric data of sections by using a 3D reconstruction algorithm (e.g., filtered back projection). The preliminary quantitative X-ray performance of our CBCT system was investigated by using the American Association of Physicists in Medicine CT phantom in terms of spatial resolution, contrast resolution, and CT number linearity for mobile or fixed C-arm based CBCT application with limited rotational geometry. The novel results of the projection data with different scanning angles and angular increments in the orbital gantry platform were acquired and evaluated experimentally

Normalized noise power spectrum of full field digital mammography detector system

International Nuclear Information System (INIS)

Norriza Mohd Isa; Wan Muhamad Saridan Wan Hassan

2009-01-01

Full text: A method to measure noise power spectrum of a full field digital mammography system is presented. The effect of X-ray radiation dose, size and configuration of region of interest on normalized noise power spectrum (NNPS) was investigated. Flat field images were acquired using RQA-M2 beam quality technique (Mo/Mo anode-filter, 28 kV, 2 mm Al) with different clinical radiation doses. The images were cropped at about 4 cm from the edge of the breast wall and then divided into different size of non-overlapping or overlapping segments. NNPS was determined through de trending, 2-D fast Fourier transformation and normalization. Our measurement shows that high radiation dose gave lower NNPS at a specific beam quality. (author)

Contrast-detail analysis of three flat panel detectors for digital radiography

International Nuclear Information System (INIS)

Borasi, Giovanni; Samei, Ehsan; Bertolini, Marco; Nitrosi, Andrea; Tassoni, Davide

2006-01-01

In this paper we performed a contrast detail analysis of three commercially available flat panel detectors, two based on the indirect detection mechanism (GE Revolution XQ/i, system A, and Trixell/Philips Pixium 4600, system B) and one based on the direct detection mechanism (Hologic DirectRay DR 1000, system C). The experiment was conducted using standard x-ray radiation quality and a widely used contrast-detail phantom. Images were evaluated using a four alternative forced choice paradigm on a diagnostic-quality softcopy monitor. At the low and intermediate exposures, systems A and B gave equivalent performances. At the high dose levels, system A performed better than system B in the entire range of target sizes, even though the pixel size of system A was about 40% larger than that of system B. At all the dose levels, the performances of the system C (direct system) were lower than those of system A and B (indirect systems). Theoretical analyses based on the Perception Statistical Model gave similar predicted SNR T values corresponding to an observer efficiency of about 0.08 for systems A and B and 0.05 for system C

Prototype of a flat-panel photoreactor using TiO2 nanoparticles coated on transparent granules for the degradation of Methylene Blue under solar illumination

Directory of Open Access Journals (Sweden)

Sutisna

2017-07-01

Full Text Available The purpose of this work is to design a prototype of a flat-panel (FP photoreactor for wastewater treatment via solar illumination using TiO2 nano-photocatalysts. The TiO2 nanoparticles are initially coated on transparent plastic granules to avoid the difficulties associated with the recovery of nanoparticles after completing the treatment process. The coated granules were distributed in the space inside the reactor panel. The upper cover of the reactor is a transparent material that allows light penetration to activate the catalyst. Wastewater is circulated into the spaces between the coated granules. When exposed to solar illumination, photocatalytic reactions occur on nearly the entire surface of the coated granules. To test the reactor viability, we used technical grade TiO2 (for affordability and a solution of Methylene Blue (MB as a sample of wastewater. The photoreactor was tested for treating 30 L of MB solution with an initial concentration of 25 mg L−1. We observed that the reactor was able to degrade more than 98% of the MB in the solution after 48 h of solar illumination. The performance of the FP photoreactor was also improved by arranging several reactor panels in series. Using four panels, we observed that the complete decomposition of the same MB solution can be achieved within 10 h. The proposed FP photoreactor is a very promising alternative for use in decomposing recalcitrant organic pollutants in wastewater.

JTEC panel on display technologies in Japan

Science.gov (United States)

Tannas, Lawrence E., Jr.; Glenn, William E.; Credelle, Thomas; Doane, J. William; Firester, Arthur H.; Thompson, Malcolm

1992-01-01

This report is one in a series of reports that describes research and development efforts in Japan in the area of display technologies. The following are included in this report: flat panel displays (technical findings, liquid crystal display development and production, large flat panel displays (FPD's), electroluminescent displays and plasma panels, infrastructure in Japan's FPD industry, market and projected sales, and new a-Si active matrix liquid crystal display (AMLCD) factory); materials for flat panel displays (liquid crystal materials, and light-emissive display materials); manufacturing and infrastructure of active matrix liquid crystal displays (manufacturing logistics and equipment); passive matrix liquid crystal displays (LCD basics, twisted nematics LCD's, supertwisted nematic LCD's, ferroelectric LCD's, and a comparison of passive matrix LCD technology); active matrix technology (basic active matrix technology, investment environment, amorphous silicon, polysilicon, and commercial products and prototypes); and projection displays (comparison of Japanese and U.S. display research, and technical evaluation of work).

Robot arm based flat panel CT-guided electromagnetic tracked spine interventions: phantom and animal model experiments.

Science.gov (United States)

Penzkofer, Tobias; Isfort, Peter; Bruners, Philipp; Wiemann, Christian; Kyriakou, Yiannis; Kalender, Willi A; Günther, Rolf W; Schmitz-Rode, Thomas; Mahnken, Andreas H

2010-11-01

To evaluate accuracy and procedure times of electromagnetic tracking (EMT) in a robotic arm mounted flat panel setting using phantom and animal cadaveric models. A robotic arm mounted flat panel (RMFP) was used in combination with EMT to perform anthropomorphic phantom (n = 90) and ex vivo pig based punctures (n = 120) of lumbar facet joints (FJ, n = 120) and intervertebral discs (IVD, n = 90). Procedure accuracies and times were assessed and evaluated. FJ punctures were carried out with a spatial accuracy of 0.8 ± 0.9 mm (phantom) and 0.6 ± 0.8 mm (ex vivo) respectively. While IVD punctures showed puncture deviations of 0.6 ± 1.2 mm (phantom) and 0.5 ± 0.6 mm (ex vivo), direct and angulated phantom based punctures had accuracies of 0.8 ± 0.9 mm and 1.0 ± 1.3 mm. Planning took longer for ex vivo IVD punctures compared to phantom model interventions (39.3 ± 17.3 s vs. 20.8 ± 5.0 s, p = 0.001) and for angulated vs. direct phantom FJ punctures (19.7 ± 5.1 s vs. 28.6 ± 7.8 s, p < 0.001). Puncture times were longer for ex vivo procedures when compared to phantom model procedures in both FJ (37.9 ± 9.0 s vs. 23.6 ± 7.2 s, p = 0.001) and IVD punctures (43.9 ± 16.1 s vs. 31.1 ± 6.4 s, p = 0.026). The combination of RMFP with EMT provides an accurate method of navigation for spinal interventions such as facet joint punctures and intervertebral disc punctures.

[Design of flat field holographic concave grating for near-infrared spectrophotometer].

Science.gov (United States)

Xiang, Xian-Yi; Wen, Zhi-Yu

2008-07-01

Near-infrared spectrum analysis can be used to determine the nature or test quantitatively some chemical compositions by detecting molecular double frequency and multiple frequency absorption. It has been used in agriculture, biology, petrifaction, foodstuff, medicament, spinning and other fields. Near-infrared spectrophotometer is the main apparatus for near-infrared spectrum analysis, and the grating is the most important part of the apparatus. Based on holographic concave grating theory and optic design software CODE V, a flat field holographic concave grating for near-infrared spectrophotometer was designed from primary structure, which relied on global optimization of the software. The contradiction between wide spectrum bound and limited spectrum extension was resolved, aberrations were reduced successfully, spectrum information was utilized fully, and the optic structure of spectrometer was highly efficient. Using CODE V software, complex high-order aberration equations need not be solved, the result can be evaluated quickly, flat field and resolving power can be kept in balance, and the work efficiency is also enhanced. A paradigm of flat field holographic concave grating is given, it works between 900 nm to 1 700 nm, the diameter of the concave grating is 25 mm, and F/ # is 1. 5. The design result was analyzed and evaluated. It was showed that if the slit source, whose width is 50 microm, is used to reconstruction, the theoretic resolution capacity is better than 6.3 nm.

Normalized Noise Power Spectrum of Full Field Digital Mammography System

International Nuclear Information System (INIS)

Isa, Norriza Mohd; Wan Hassan, Wan Muhamad Saridan

2010-01-01

A method to measure noise power spectrum of a full field digital mammography system is presented. The effect of X-ray radiation dose, size and configuration of region of interest on normalized noise power spectrum (NNPS) was investigated. Flat field images were acquired using RQA-M2 beam quality technique (Mo/Mo anode-filter, 28 kV, 2 mm Al) with different clinical radiation doses. The images were cropped at about 4 cm from the edge of the breast wall and then divided into different size of non-overlapping or overlapping segments. NNPS was determined through detrending, 2-D fast Fourier transformation and normalization. Our measurement shows that high radiation dose gave lower NNPS at a specific beam quality.

TU-E-217BCD-06: Cone Beam Breast CT with a High Resolution Flat Panel Detector-Improvement of Calcification Visibility.

Science.gov (United States)

Shen, Y; Zhong, Y; Lai, C; Wang, T; Shaw, C

2012-06-01

To investigate the advantage of a high resolution flat panel detector for improving the visibility of microcalcifications (MCs) in cone beam breast CT Methods: A paraffin cylinder was used to simulate a 100% adipose breast. Calcium carbonate grains, ranging from 125-140 μm to 224 - 250 μm in size, were used to simulate the MCs. Groups of 25 same size MCs were embedded at the phantom center. The phantom was scanned with a bench-top CBCT system at various exposure levels. A 75μm pitch flat panel detector (Dexela 2923, Perkin Elmer) with 500μm thick CsI scintillator plate was used as the high resolution detector. A 194 μm pitch detector (Paxscan 4030CB, Varian Medical Systems) was used for reference. 300 projection images were acquired over 360° and reconstructed. The images were reviewed by 6 readers. The MC visibility was quantified as the fraction of visible MCs and averaged for comparison. The visibility was plotted as a function of the estimated dose level for various MC sizes and detectors. The MTFs and DQEs were measured and compared. For imaging small (200 μm and smaller) MCs, the visibility achieved with the 75μm pitch detector was found to be significantly higher than those achieved with the 194μm pitch detector. For imaging larger MCs, there was little advantage in using the 75μm pitch detector. Using the 75μm pitch detector, MCs as small as 180 μm could be imaged to achieve a visibility of 78% with an isocenter tissue dose of ∼20 mGys versus 62% achieved with the 194 μm pitch detector at the same dose level. It was found that a high pitch flat panel detector had the advantages of extending its imaging capability to higher frequencies thus helping improve the visibility when used to image small MCs. This work was supported in part by grants CA104759, CA13852 and CA124585 from NIH-NCI, a grant EB00117 from NIH-NIBIB, and a subcontract from NIST-ATP. © 2012 American Association of Physicists in Medicine.

A compact high resolution flat panel PET detector based on the new 4-side buttable MPPC for biomedical applications.

Science.gov (United States)

Wang, Qiang; Wen, Jie; Ravindranath, Bosky; O'Sullivan, Andrew W; Catherall, David; Li, Ke; Wei, Shouyi; Komarov, Sergey; Tai, Yuan-Chuan

2015-09-11

Compact high-resolution panel detectors using virtual pinhole (VP) PET geometry can be inserted into existing clinical or pre-clinical PET systems to improve regional spatial resolution and sensitivity. Here we describe a compact panel PET detector built using the new Though Silicon Via (TSV) multi-pixel photon counters (MPPC) detector. This insert provides high spatial resolution and good timing performance for multiple bio-medical applications. Because the TSV MPPC design eliminates wire bonding and has a package dimension which is very close to the MPPC's active area, it is 4-side buttable. The custom designed MPPC array (based on Hamamatsu S12641-PA-50(x)) used in the prototype is composed of 4 × 4 TSV-MPPC cells with a 4.46 mm pitch in both directions. The detector module has 16 × 16 lutetium yttrium oxyorthosilicate (LYSO) crystal array, with each crystal measuring 0.92 × 0.92 × 3 mm 3 with 1.0 mm pitch. The outer diameter of the detector block is 16.8 × 16.8 mm 2 . Thirty-two such blocks will be arranged in a 4 × 8 array with 1 mm gaps to form a panel detector with detection area around 7 cm × 14 cm in the full-size detector. The flood histogram acquired with Ge-68 source showed excellent crystal separation capability with all 256 crystals clearly resolved. The detector module's mean, standard deviation, minimum (best) and maximum (worst) energy resolution were 10.19%, +/-0.68%, 8.36% and 13.45% FWHM, respectively. The measured coincidence time resolution between the block detector and a fast reference detector (around 200 ps single photon timing resolution) was 0.95 ns. When tested with Siemens Cardinal electronics the performance of the detector blocks remain consistent. These results demonstrate that the TSV-MPPC is a promising photon sensor for use in a flat panel PET insert composed of many high resolution compact detector modules.

PHYSICAL FIELDS OF CIRCULAR CYLINDRICAL PIEZOCERAMIC RECEIVER IN PRESENCE OF A FLAT ACOUSTIC SOFT SCREEN

Directory of Open Access Journals (Sweden)

A. V. Derepa

2017-01-01

Full Text Available System in the form of a circular cylindrical piezoceramic transducer near a flat acoustic screen was analyzed. The aim of the work was to solve the problem of receiving plane sound waves by «cylindrical piezoceramic transducer – flat acoustically soft screen» system.Considered system was characterized by a violation of the radial symmetry of the radiation load of the transducer while maintaining the radial symmetry of the electric load. At the same time, the energy perceived by the system under consideration is distributed between all modes of oscillation of the transducer, while the conversion of mechanical energy into electric is realized only at zero mole of oscillations.Special attention was paid to the method of coupled fields in multiply connected domains using the imaging method. The design model of the «transducer–creen» system was formulated taking into account the interaction of acoustic, mechanical and electric fields in the process of energy conversion, the interaction of a cylindrical transducer with a flat screen and the interaction of a converter with elastic media outside and inside it. The physical fields of the system under consideration were determined by following solutions: the wave equation; equations of motion of thin piezoceramic cylindrical shells in displacements; equations of stimulated electrostatics for piezoceramics for given boundary conditions, conditions for coupling fields at interfaces and electrical conditions.A general conclusion was made concerning solving of an infinite system of linear algebraic equations with respect to the unknown coefficients of the expansion of the fields. As an example of the application of the obtained relations, a calculation was made and an analysis of the dependences of the electric fields of the system under consideration for various parameters of its construction on the direction of arrival on the plane wave system was conducted.

Clinical evaluation of digital radiography based on a large-area cesium iodide-amorphous silicon flat-panel detector compared with screen-film radiography for skeletal system and abdomen

International Nuclear Information System (INIS)

Okamura, Terue; Tanaka, Saori; Koyama, Koichi; Norihumi, Nishida; Daikokuya, Hideo; Matsuoka, Toshiyuki; Yamada, Ryusaku; Kishimoto, Kenji; Hatagawa, Masakatsu; Kudoh, Hiroaki

2002-01-01

The aim of this clinical study was to compare the image quality of digital radiography using the new digital Bucky system based on a flat-panel detector with that of a conventional screen-film system for the skeletal structure and the abdomen. Fifty patients were examined using digital radiography with a flat-panel detector and screen-film systems, 25 for the skeletal structures and 25 for the abdomen. Six radiologists judged each paired image acquired under the same exposure parameters concerning three observation items for the bone and six items for the abdomen. Digital radiographic images for the bone were evaluated to be similar to screen-film images at the mean of 42.2%, to be superior at 50.2%, and to be inferior at 7.6%. Digital radiographic images for the abdomen were judged to be similar to screen-film images at the mean of 43.4%, superior at 52.4%, and inferior at 4.2%; thus, digital radiographic images were estimated to be either similar as or superior to screen-film images at over 92% for the bone and abdomen. On the statistical analysis, digital radiographic images were also judged to be preferred significantly in the most items for the bone and abdomen. In conclusion, the image quality of digital radiography with a flat-panel detector was superior to that of a screen-film system under the same exposure parameters, suggesting that dose reduction is possible with digital radiography. (orig.)

High-resolution dynamic angiography using flat-panel volume CT: feasibility demonstration for neuro and lower limb vascular applications

International Nuclear Information System (INIS)

Mehndiratta, Amit; Rabinov, James D.; Grasruck, Michael; Liao, Eric C.; Crandell, David; Gupta, Rajiv

2015-01-01

This paper evaluates a prototype flat-panel volume CT (fpVCT) for dynamic in vivo imaging in a variety of neurovascular and lower limb applications. Dynamic CTA was performed on 12 patients (neuro = 8, lower limb = 4) using an fpVCT with 120 kVp, 50 mA, rotation time varying from 8 to 19 s, and field of view of 25 x 25 x 18 cm 3 . Four-dimensional data sets (i.e. 3D images over time) were reconstructed and reviewed. Dynamic CTA demonstrated sufficient spatio-temporal resolution to elucidate first-pass and recirculation dynamics of contrast bolus through neurovasclar pathologies and phasic blood flow though lower-limb vasculature and grafts. The high spatial resolution of fpVCT resulted in reduced partial volume and metal beam-hardening artefacts. This facilitated assessment of vascular lumen in the presence of calcified plaque and evaluation of fractures, especially in the presence of fixation hardware. Evaluation of arteriovenous malformation using dynamic fpVCT angiography was of limited utility. Dynamic CTA using fpVCT can visualize time-varying phenomena in neuro and lower limb vascular applications and has sufficient diagnostic imaging quality to evaluate a number of pathologies affecting these regions. (orig.)

A Comparative Study of the Analysis, Numerical Modelling and Experimental Test on a Sandwich Panel with Plane and Profiled Facings

Directory of Open Access Journals (Sweden)

Raluca Hohan

2010-01-01

Full Text Available Sandwich panels are remarkable products because they can be as strong as a solid material but with less weight. The analysis that is required to predict the stresses and deflections in panels with flat or lightly profiled facings is that of conventional beam theory but with the addition of shear deformation. Knowing that the profiled sheets bring an increase of the flexural stiffness, formulas showing the calculus of a panel with flat and profiled facings are established. A comparison between the results of a mathematical calculus, an experimental test and a numerical modelling is provided.

Effect of air flow, panel curvature, and internal pressurization on field-incidence transmission loss

Science.gov (United States)

Koval, L. R.

1976-01-01

In the context of sound transmission through aircraft fuselage panels, equations for the field-incidence transmission loss (TL) of a single-walled panel are derived that include the effects of external air flow, panel curvature, and internal fuselage pressurization. Flow is shown to provide a modest increase in TL that is uniform with frequency up to the critical frequency. The increase is about 2 dB at Mach number M = 0.5, and about 3.5 dB at M = 1. Above the critical frequency where TL is damping controlled, the increase can be slightly larger at certain frequencies. Curvature is found to stiffen the panel, thereby increasing the TL at low frequencies, but also to introduce a dip at the 'ring frequency' of a full cylinder having the same radius as the panel. Pressurization appears to produce a slight decrease in TL throughout the frequency range, and also slightly shifts the dips at the critical frequency and at the ring frequency.

77 FR 31877 - Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Scheduling of Full Five...

Science.gov (United States)

2012-05-30

... INTERNATIONAL TRADE COMMISSION [Investigation Nos. 701-TA-350 and 731-TA-616 and 618 (Third Review)] Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Scheduling of Full Five-Year Reviews... corrosion-resistant carbon steel flat products from Korea and the antidumping duty orders on corrosion...

Contact-free handling using actively controlled electrostatic levitating fields

NARCIS (Netherlands)

Woo, S.J.

2012-01-01

In general electric field forces have the distinctive property of being able to mediate forces to virtually any material in a fully non-invasive and contact-free fashion. Based on this property, electrostatic levitation holds great promise for the semiconductor, solar panel, and flat-panel display

Multiple Site Damage in Flat Panel Testing

National Research Council Canada - National Science Library

Shrage, Daniel

2000-01-01

This report aimed to experimentally verify analytical models that predict the residual strength of representative aircraft structures, such as wide panels, that are subjected to Multiple Site Damage (MSD...

Normalized noise power spectrum of full field digital mammography system

International Nuclear Information System (INIS)

Norriza Mohd Isa; Wan Muhamad Saridan Wan Hassan

2009-01-01

A method to measure noise power spectrum of a full field digital mammography system is presented. The effect of X-ray radiation dose, size and configuration of region of interest on normalized noise power spectrum (NNPS) was investigated. Flat field images were acquired using RQA-M2 beam quality technique (Mo/Mo anode-filter, 28 kV, 2 mm Al) with different clinical radiation doses. The images were cropped at about 4 cm from the edge of the breast wall and then divided into different size of non-overlapping or overlapping segments. NNPS was determined through detrending, 2-D fast Fourier transformation and normalization. Our measurement shows that high radiation dose gave lower NNPS at a specific beam quality. (Author)

Aging of imaging properties of a CMOS flat-panel detector for dental cone-beam computed tomography

Science.gov (United States)

Kim, D. W.; Han, J. C.; Yun, S.; Kim, H. K.

2017-01-01

We have experimentally investigated the long-term stability of imaging properties of a flat-panel detector in conditions used for dental x-ray imaging. The detector consists of a CsI:Tl layer and CMOS photodiode pixel arrays. Aging simulations were carried out using an 80-kVp x-ray beam at an air-kerma rate of approximately 5 mGy s-1 at the entrance surface of the detector with a total air kerma of up to 0.6 kGy. Dark and flood-field images were periodically obtained during irradiation, and the mean signal and noise levels were evaluated for each image. We also evaluated the modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). The aging simulation showed a decrease in both the signal and noise of the gain-offset-corrected images, but there was negligible change in the signal-to-noise performance as a function of the accumulated dose. The gain-offset correction for analyzing images resulted in negligible changes in MTF, NPS, and DQE results over the total dose. Continuous x-ray exposure to a detector can cause degradation in the physical performance factors such the detector sensitivity, but linear analysis of the gain-offset-corrected images can assure integrity of the imaging properties of a detector during its lifetime.

Flat-space singletons

International Nuclear Information System (INIS)

Fronsdal, C.

1987-01-01

Singletons exist, as particles and as local fields, only in 3+2 de Sitter space. Their kinematical properties make them natural candidates for constituents of massless fields, and perhaps for quarks. It is interesting to find out how to describe this type of compositeness in flat space. A theory of interacting singleton fields in de Sitter space is now available, and in this paper we study the flat-space limit of the Green's functions of that theory. The flat-space limit is an autonomous theory of Green's functions, but is not an operator field theory. The three-point function is calculated and its flat-space limit is found to reveal glimpses of a physical interpretation. Causal and spectral properties are in accord with the tenets of axiomatic field theory. The theory is a generalization of local field theory, in which photons appear as composite objects although the physical S matrix is the same as in conventional QED

Comparison of imaging properties of direct-type and indirect-type of flat-panel detector

International Nuclear Information System (INIS)

Matsumoto, Masao; Suekane, Koji; Ichimaru, Yasunobu; Ogata, Yuji; Inamura, Kiyonari; Kanai, Kouzou; Kanamori, Hitoshi

2002-01-01

A Flat-Panel Detector (FPD) has many advantages such as eliminating cassette handling and being able to display a preview image immediately in addition to the digital image processing and the networking. Thus, the FPD has ability to innovate the radiology department. We measured and evaluated the digital and over-all imaging properties (characteristic curves, modulation Transfer Functions, Wiener spectra and Noise Equivalent Quanta (NEQ) for the direct-type and indirect-type of FPD. The pre-sampling and overall NEQ of the indirect-type of FPD were better than the NEQ of the direct-type of FPD at lower spatial frequencies, but were worse at higher spatial frequencies. The FPD can take image data at real-time and be easy to digitalize. From these results, Screen/Film system and Computed Radiography system will be replaced by the FPD system, together with diffusion of CAD, cone beam Computed Tomography (CT) system and open-type Magnetic Resonance Imagining (MRI) system. (T. Tanaka)

Human health and ecological toxicity potentials due to heavy metal content in waste electronic devices with flat panel displays

International Nuclear Information System (INIS)

Lim, Seong-Rin; Schoenung, Julie M.

2010-01-01

Display devices such as cathode-ray tube (CRT) televisions and computer monitors are known to contain toxic substances and have consequently been banned from disposal in landfills in the State of California and elsewhere. New types of flat panel display (FPD) devices, millions of which are now purchased each year, also contain toxic substances, but have not previously been systematically studied and compared to assess the potential impact that could result from their ultimate disposal. In the current work, the focus is on the evaluation of end-of-life toxicity potential from the heavy metal content in select FPD devices with the intent to inform material selection and design-for-environment (DfE) decisions. Specifically, the metals antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, selenium, silver, vanadium, and zinc in plasma TVs, LCD (liquid crystal display) TVs, LCD computer monitors and laptop computers are considered. The human health and ecotoxicity potentials are evaluated through a life cycle assessment perspective by combining data on the respective heavy metal contents, the characterization factors in the U.S. EPA Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI), and a pathway and impact model. Principal contributors to the toxicity potentials are lead, arsenic, copper, and mercury. Although the heavy metal content in newer flat panel display devices creates less human health toxicity potential than that in CRTs, for ecological toxicity, the new devices are worse, especially because of the mercury in LCD TVs and the copper in plasma TVs.

Design of wide flat-topped low transverse field solenoid magnet

International Nuclear Information System (INIS)

Jing Xiaobing; Chen Nan; Li Qin

2010-01-01

A wide flat-topped low transverse error field solenoid magnet design for linear induction accelerator is presented. The design features non-uniform winding to reduce field fluctuation due to the magnets' gap, and homogenizer rings within the solenoid to greatly reduce the effects of winding errors. Numerical modeling of several designs for 12 MeV linear induction accelerator (LIA) in China Academy of Engineering Physics has demonstrated that by using these two techniques the magnetic field fluctuations in the accelerator gap can be reduced by 70% and the transverse error field can be reduced by 96.5%. (authors)

High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging

Science.gov (United States)

Abu Anas, Emran Mohammad; Kim, Jae Gon; Lee, Soo Yeol; Kamrul Hasan, Md

2011-10-01

The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging

International Nuclear Information System (INIS)

Anas, Emran Mohammad Abu; Hasan, Md Kamrul; Kim, Jae Gon; Lee, Soo Yeol

2011-01-01

The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

Cone-Beam CT with Flat-Panel-Detector Digital Angiography System: Early Experience in Abdominal Interventional Procedures

International Nuclear Information System (INIS)

Hirota, Shozo; Nakao, Norio; Yamamoto, Satoshi; Kobayashi, Kaoru; Maeda, Hiroaki; Ishikura, Reiichi; Miura, Koui; Sakamoto, Kiyoshi; Ueda, Ken; Baba, Rika

2006-01-01

We developed a cone-beam computed tomography (CBCT) system equipped with a large flat-panel detector. Data obtained by 200 o rotation imaging are reconstructed by means of CBCT to generate three-dimensional images. We report the use of CBCT angiography using CBCT in 10 patients with 8 liver malignancies and 2 hypersplenisms during abdominal interventional procedures. CBCT was very useful for interventional radiologists to confirm a perfusion area of the artery catheter wedged on CT by injection of contrast media through the catheter tip, although the image quality was slightly degraded, scoring as 2.60 on average by streak artifacts. CBCT is space-saving because it does not require a CT system with a gantry, and it is also time-saving because it does not require the transfer of patients

Towards the mechanism of DC electric field effect on flat premixed flames

NARCIS (Netherlands)

Volkov, E.N.; Sepman, A.V.; Kornilov, V.N.; Konnov, A.A.; Shoshyn, Y.; Goey, de L.P.H.

2009-01-01

The influence of a DC electric field on CH4/air flat flame characteristics was experimentally investigated. To understand the mechanism of the electric field influence on a flame a number of experiments were conducted: measurements of the flame burning velocities using the heat flux method, OH LIF

Characteristics and applications of a flat panel computer tomography system; Eigenschaften und Anwendungen der Flaechendetektor-basierten Volumen-Computertomographie

Energy Technology Data Exchange (ETDEWEB)

Knollmann, F.; Valencia, R.; Obenauer, S. [Abt. Diagnostische Radiologie, Klinikum der Georg-August-Univ. Goettingen (Germany); Buhk, J.H. [Abt. Neuroradiologie, Univ. Goettingen (Germany)

2006-09-15

Purpose: to assess a new flat panel volume computed tomography (FP-VCT) with very high isotropic spatial resolution as well as high Z-axis coverage. Materials and Methods: The prototype of an FP-VCT scanner with a detector cell size of 0.2 mm was used for numerous phantom studies, specimen examinations, and animal research projects. Results: The high spatial resolution of the new system can be used to accurately determine solid tumor volume, thus allowing for earlier assessment of the therapeutic response. In animal experimentation, whole-body perfusion mapping of mice is feasible. The high spatial resolution also improves the classification of coronary artery atherosclerotic plaques in the isolated post mortem human heart. With the depiction of intramyocardial segments of the coronary arteries, investigations of myocardial collateral circulation are feasible. In skeletal applications, an accurate analysis of the smallest bony structures, e.g., petrous bone and dental preparations, can be successfully performed, as well as investigations of repetitive studies of fracture healing and the treatment of osteoporosis. Conclusion: The introduction of FP-VCT opens up new applications for CT, including the field of molecular imaging, which are highly attractive for future clinical applications. Present limitations include limited temporal resolution and necessitate further improvement of the system. (orig.)

High-resolution dynamic angiography using flat-panel volume CT: feasibility demonstration for neuro and lower limb vascular applications

Energy Technology Data Exchange (ETDEWEB)

Mehndiratta, Amit [Massachusetts General Hospital, Department of Radiology, Harvard Medical School, Boston, MA (United States); University of Oxford, Institute of Biomedical Engineering and Keble College, Oxford (United Kingdom); Indian Institute of Technology Delhi and All India Institute of Medical Science, Centre for Biomedical Engineering, New Delhi (India); Rabinov, James D. [Massachusetts General Hospital, Interventional Neuroradiology, Harvard Medical School, Boston, MA (United States); Grasruck, Michael [Siemens Medical Solutions, Forchheim (Germany); Liao, Eric C. [Massachusetts General Hospital, Department of Plastic and Reconstructive Surgery and Center for Regenerative Medicine, Harvard Medical School, Boston, MA (United States); Crandell, David [Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Charlestown, MA (United States); Gupta, Rajiv [Massachusetts General Hospital, Department of Radiology, Harvard Medical School, Boston, MA (United States)

2015-07-15

This paper evaluates a prototype flat-panel volume CT (fpVCT) for dynamic in vivo imaging in a variety of neurovascular and lower limb applications. Dynamic CTA was performed on 12 patients (neuro = 8, lower limb = 4) using an fpVCT with 120 kVp, 50 mA, rotation time varying from 8 to 19 s, and field of view of 25 x 25 x 18 cm{sup 3}. Four-dimensional data sets (i.e. 3D images over time) were reconstructed and reviewed. Dynamic CTA demonstrated sufficient spatio-temporal resolution to elucidate first-pass and recirculation dynamics of contrast bolus through neurovasclar pathologies and phasic blood flow though lower-limb vasculature and grafts. The high spatial resolution of fpVCT resulted in reduced partial volume and metal beam-hardening artefacts. This facilitated assessment of vascular lumen in the presence of calcified plaque and evaluation of fractures, especially in the presence of fixation hardware. Evaluation of arteriovenous malformation using dynamic fpVCT angiography was of limited utility. Dynamic CTA using fpVCT can visualize time-varying phenomena in neuro and lower limb vascular applications and has sufficient diagnostic imaging quality to evaluate a number of pathologies affecting these regions. (orig.)

Static and fatigue experimental tests on a full scale fuselage panel and FEM analyses

Directory of Open Access Journals (Sweden)

Raffaele Sepe

2016-02-01

Full Text Available A fatigue test on a full scale panel with complex loading condition and geometry configuration has been carried out using a triaxial test machine. The demonstrator is made up of two skins which are linked by a transversal butt-joint, parallel to the stringer direction. A fatigue load was applied in the direction normal to the longitudinal joint, while a constant load was applied in the longitudinal joint direction. The test panel was instrumented with strain gages and previously quasi-static tests were conducted to ensure a proper load transferring to the panel. In order to support the tests, geometric nonlinear shell finite element analyses were conducted to predict strain and stress distributions. The demonstrator broke up after about 177000 cycles. Subsequently, a finite element analysis (FEA was carried out in order to correlate failure events; due to the biaxial nature of the fatigue loads, Sines criterion was used. The analysis was performed taking into account the different materials by which the panel is composed. The numerical results show a good correlation with experimental data, successfully predicting failure locations on the panel.

A full scope nuclear power plant simulator for multiple reactor types with virtual control panels

International Nuclear Information System (INIS)

Yonezawa, Hisanori; Ueda, Hiroki; Kato, Takahisa

2017-01-01

This paper summarizes a full scope nuclear power plant simulator for multiple reactor types with virtual control panels which Toshiba developed and delivered. After the Fukushima DAIICHI nuclear power plants accident, it is required that all the people who are engaged in the design, manufacturing, operation, maintenance, management and regulation for the nuclear power plant should learn the wide and deep knowledge about the nuclear power plant design including the severe accident. For this purpose, the training with a full scope simulator is one of the most suitable ways. However the existing full scope simulators which are consist of the control panels replica of the referenced plants are costly and they are hard to remodel to fit to the real plant of the latest condition. That's why Toshiba developed and delivered the new concept simulator system which covers multiple referenced plants even though they have different design like BWR and PWR. The control panels of the simulator are made by combining 69 large Liquid Crystal Display (LCD) panels with touch screen instead of a control panel replica of referenced plant. The screen size of the each panel is 42 inches and 3 displays are arranged in tandem for one unit and 23 units are connected together. Each panel displays switches, indicators, recorders and lamps with the Computer Graphics (CG) and trainees operate them with touch operations. The simulator includes a BWR and a PWR simulator model, which enable trainees to learn the wide and deep knowledge about the nuclear power plant of BWR and PWR reactor types. (author)

The impact of round window vs cochleostomy surgical approaches on interscalar excursions in the cochlea: Preliminary results from a flat-panel computed tomography study

Directory of Open Access Journals (Sweden)

Nicole T. Jiam

2016-09-01

Full Text Available Objective: To evaluate incidence of interscalar excursions between round window (RW and cochleostomy approaches for cochlear implant (CI insertion. Methods: This was a retrospective case-comparison. Flat-panel CT (FPCT scans for 8 CI users with Med-El standard length electrode arrays were collected. Surgical technique was identified by a combination of operative notes and FPCT imaging. Four cochleae underwent round window insertion and 4 cochleae underwent cochleostomy approaches anterior and inferior to the round window. Results: In our pilot study, cochleostomy approaches were associated with a higher likelihood of interscalar excursion. Within the cochleostomy group, we found 29% of electrode contacts (14 of 48 electrodes to be outside the scala tympani. On the other hand, 8.5% of the electrode contacts (4 of 47 electrodes in the round window insertion group were extra-scalar to the scala tympani. These displacements occurred at a mean angle of occurrence of 364° ± 133°, near the apex of the cochlea. Round window electrode displacements tend to localize at angle of occurrences of 400° or greater. Cochleostomy electrodes occurred at an angle of occurrence of 19°–490°. Conclusions: Currently, the optimal surgical approach for standard CI electrode insertion is highly debated, to a certain extent due to a lack of post-operative assessment of intracochlear electrode contact. Based on our preliminary findings, cochleostomy approach is associated with an increased likelihood of interscalar excursions, and these findings should be further evaluated with future prospective studies. Keywords: Cochlear implantation, Round window insertion, Cochleostomy, Interscalar excursion, Electrode position, Flat-panel computed tomography, Surgical approach

The large-scale peculiar velocity field in flat models of the universe

International Nuclear Information System (INIS)

Vittorio, N.; Turner, M.S.

1986-10-01

The inflationary Universe scenario predicts a flat Universe and both adiabatic and isocurvature primordial density perturbations with the Zel'dovich spectrum. The two simplest realizations, models dominated by hot or cold dark matter, seem to be in conflict with observations. Flat models are examined with two components of mass density, where one of the components of mass density is smoothly distributed and the large-scale (≥10h -1 MpC) peculiar velocity field for these models is considered. For the smooth component relativistic particles, a relic cosmological term, and light strings are considered. At present the observational situation is unsettled; but, in principle, the large-scale peculiar velocity field is very powerful discriminator between these different models. 61 refs

Design and test of a flat-top magnetic field system driven by capacitor banks.

Science.gov (United States)

Jiang, Fan; Peng, Tao; Xiao, Houxiu; Zhao, Jianlong; Pan, Yuan; Herlach, Fritz; Li, Liang

2014-04-01

An innovative method for generating a flat-top pulsed magnetic field by means of capacitor banks is developed at the Wuhan National High Magnetic Field Center (WHMFC). The system consists of two capacitor banks as they are normally used to generate a pulsed field. The two discharge circuits (the magnet circuit and the auxiliary circuit) are coupled by a pulse transformer such that the electromotive force (EMF) induced via the transformer in the magnet circuit containing the magnet coil is opposed to the EMF of the capacitor bank. At a certain point before the current pulse in the coil reaches its peak, the auxiliary circuit is triggered. With optimized parameters for charging voltage and trigger delay, the current in the magnet circuit can be approximately kept constant to obtain a flat-top. A prototype was developed at the WHMFC; the magnet circuit was energized by seven 1 MJ (3.2 mF/25 kV) capacitor modules and the auxiliary circuit by four 1 MJ modules. Fields up to 41 T with 6 ms flat-top have been obtained with a conventional user magnet used at the WHMFC.

Scalar field collapse in a conformally flat spacetime

Energy Technology Data Exchange (ETDEWEB)

Chakrabarti, Soumya; Banerjee, Narayan [Indian Institute of Science Education and Research, Kolkata, Department of Physical Sciences, Mohanpur, West Bengal (India)

2017-03-15

The collapse scenario of a scalar field along with a perfect fluid distribution was investigated for a conformally flat spacetime. The theorem for the integrability of an anharmonic oscillator has been utilized. For a pure power-law potential of the form φ{sup n+1}, it was found that a central singularity is formed which is covered by an apparent horizon for n > 0 and n < -3. Some numerical results have also been presented for a combination of two different powers of φ in the potential. (orig.)

Metal artifact reduction for flat panel detector intravenous CT angiography in patients with intracranial metallic implants after endovascular and surgical treatment.

Science.gov (United States)

Pjontek, Rastislav; Önenköprülü, Belgin; Scholz, Bernhard; Kyriakou, Yiannis; Schubert, Gerrit A; Nikoubashman, Omid; Othman, Ahmed; Wiesmann, Martin; Brockmann, Marc A

2016-08-01

Flat panel detector CT angiography with intravenous contrast agent injection (IV CTA) allows high-resolution imaging of cerebrovascular structures. Artifacts caused by metallic implants like platinum coils or clips lead to degradation of image quality and are a significant problem. To evaluate the influence of a prototype metal artifact reduction (MAR) algorithm on image quality in patients with intracranial metallic implants. Flat panel detector CT after intravenous application of 80 mL contrast agent was performed with an angiography system (Artis zee; Siemens, Forchheim, Germany) using a 20 s rotation protocol (200° rotation angle, 20 s acquisition time, 496 projections). The data before and after MAR of 26 patients with a total of 34 implants (coils, clips, stents) were independently evaluated by two blinded neuroradiologists. MAR improved the assessability of the brain parenchyma and small vessels (diameter metallic implants and at a distance of 6 cm (p<0.001 each, Wilcoxon test). Furthermore, MAR significantly improved the assessability of parent vessel patency and potential aneurysm remnants (p<0.005 each, McNemar test). MAR, however, did not improve assessability of stented vessels. When an intravenous contrast protocol is used, MAR significantly ameliorates the assessability of brain parenchyma, vessels, and treated aneurysms in patients with intracranial coils or clips. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: zero-spatial frequency x-ray imaging properties of the solid-state SHARP sensor structure.

Science.gov (United States)

Wronski, M; Zhao, W; Tanioka, K; Decrescenzo, G; Rowlands, J A

2012-11-01

The authors are investigating the feasibility of a new type of solid-state x-ray imaging sensor with programmable avalanche gain: scintillator high-gain avalanche rushing photoconductor active matrix flat panel imager (SHARP-AMFPI). The purpose of the present work is to investigate the inherent x-ray detection properties of SHARP and demonstrate its wide dynamic range through programmable gain. A distributed resistive layer (DRL) was developed to maintain stable avalanche gain operation in a solid-state HARP. The signal and noise properties of the HARP-DRL for optical photon detection were investigated as a function of avalanche gain both theoretically and experimentally, and the results were compared with HARP tube (with electron beam readout) used in previous investigations of zero spatial frequency performance of SHARP. For this new investigation, a solid-state SHARP x-ray image sensor was formed by direct optical coupling of the HARP-DRL with a structured cesium iodide (CsI) scintillator. The x-ray sensitivity of this sensor was measured as a function of avalanche gain and the results were compared with the sensitivity of HARP-DRL measured optically. The dynamic range of HARP-DRL with variable avalanche gain was investigated for the entire exposure range encountered in radiography∕fluoroscopy (R∕F) applications. The signal from HARP-DRL as a function of electric field showed stable avalanche gain, and the noise associated with the avalanche process agrees well with theory and previous measurements from a HARP tube. This result indicates that when coupled with CsI for x-ray detection, the additional noise associated with avalanche gain in HARP-DRL is negligible. The x-ray sensitivity measurements using the SHARP sensor produced identical avalanche gain dependence on electric field as the optical measurements with HARP-DRL. Adjusting the avalanche multiplication gain in HARP-DRL enabled a very wide dynamic range which encompassed all clinically relevant

Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: Zero-spatial frequency x-ray imaging properties of the solid-state SHARP sensor structure

International Nuclear Information System (INIS)

Wronski, M.; Zhao, W.; Tanioka, K.; DeCrescenzo, G.; Rowlands, J. A.

2012-01-01

Purpose: The authors are investigating the feasibility of a new type of solid-state x-ray imaging sensor with programmable avalanche gain: scintillator high-gain avalanche rushing photoconductor active matrix flat panel imager (SHARP-AMFPI). The purpose of the present work is to investigate the inherent x-ray detection properties of SHARP and demonstrate its wide dynamic range through programmable gain. Methods: A distributed resistive layer (DRL) was developed to maintain stable avalanche gain operation in a solid-state HARP. The signal and noise properties of the HARP-DRL for optical photon detection were investigated as a function of avalanche gain both theoretically and experimentally, and the results were compared with HARP tube (with electron beam readout) used in previous investigations of zero spatial frequency performance of SHARP. For this new investigation, a solid-state SHARP x-ray image sensor was formed by direct optical coupling of the HARP-DRL with a structured cesium iodide (CsI) scintillator. The x-ray sensitivity of this sensor was measured as a function of avalanche gain and the results were compared with the sensitivity of HARP-DRL measured optically. The dynamic range of HARP-DRL with variable avalanche gain was investigated for the entire exposure range encountered in radiography/fluoroscopy (R/F) applications. Results: The signal from HARP-DRL as a function of electric field showed stable avalanche gain, and the noise associated with the avalanche process agrees well with theory and previous measurements from a HARP tube. This result indicates that when coupled with CsI for x-ray detection, the additional noise associated with avalanche gain in HARP-DRL is negligible. The x-ray sensitivity measurements using the SHARP sensor produced identical avalanche gain dependence on electric field as the optical measurements with HARP-DRL. Adjusting the avalanche multiplication gain in HARP-DRL enabled a very wide dynamic range which encompassed all

A novel full-field experimental method to measure the local compressibility of gas diffusion media

Energy Technology Data Exchange (ETDEWEB)

Lai, Yeh-Hung; Li, Yongqiang [Electrochemical Energy Research Lab, GM R and D, Honeoye Falls, NY 14472 (United States); Rock, Jeffrey A. [GM Powertrain, Honeoye Falls, NY 14472 (United States)

2010-05-15

The gas diffusion medium (GDM) in a proton exchange membrane (PEM) fuel cell needs to simultaneously satisfy the requirements of transporting reactant gases, removing product water, conducting electrons and heat, and providing mechanical support to the membrane electrode assembly (MEA). Concerning the localized over-compression which may force carbon fibers and other conductive debris into the membrane to cause fuel cell failure by electronically shorting through the membrane, we have developed a novel full-field experimental method to measure the local thickness and compressibility of GDM. Applying a uniform air pressure upon a thin polyimide film bonded on the top surface of the GDM with support from the bottom by a flat metal substrate and measuring the thickness change using the 3-D digital image correlation technique with an out-of-plane displacement resolution less than 0.5 {mu}m, we have determined the local thickness and compressive stress/strain behavior in the GDM. Using the local thickness and compressibility data over an area of 11.2 mm x 11.2 mm, we numerically construct the nominal compressive response of a commercial Toray trademark TGP-H-060 based GDM subjected to compression by flat platens. Good agreement in the nominal stress/strain curves from the numerical construction and direct experimental flat-platen measurement confirms the validity of the methodology proposed in this article. The result shows that a nominal pressure of 1.4 MPa compressed between two flat platens can introduce localized compressive stress concentration of more than 3 MPa in up to 1% of the total area at various locations from several hundred micrometers to 1 mm in diameter. We believe that this full-field experimental method can be useful in GDM material and process development to reduce the local hard spots and help to mitigate the membrane shorting failure in PEM fuel cells. (author)

A novel full-field experimental method to measure the local compressibility of gas diffusion media

Science.gov (United States)

Lai, Yeh-Hung; Li, Yongqiang; Rock, Jeffrey A.

The gas diffusion medium (GDM) in a proton exchange membrane (PEM) fuel cell needs to simultaneously satisfy the requirements of transporting reactant gases, removing product water, conducting electrons and heat, and providing mechanical support to the membrane electrode assembly (MEA). Concerning the localized over-compression which may force carbon fibers and other conductive debris into the membrane to cause fuel cell failure by electronically shorting through the membrane, we have developed a novel full-field experimental method to measure the local thickness and compressibility of GDM. Applying a uniform air pressure upon a thin polyimide film bonded on the top surface of the GDM with support from the bottom by a flat metal substrate and measuring the thickness change using the 3-D digital image correlation technique with an out-of-plane displacement resolution less than 0.5 μm, we have determined the local thickness and compressive stress/strain behavior in the GDM. Using the local thickness and compressibility data over an area of 11.2 mm × 11.2 mm, we numerically construct the nominal compressive response of a commercial Toray™ TGP-H-060 based GDM subjected to compression by flat platens. Good agreement in the nominal stress/strain curves from the numerical construction and direct experimental flat-platen measurement confirms the validity of the methodology proposed in this article. The result shows that a nominal pressure of 1.4 MPa compressed between two flat platens can introduce localized compressive stress concentration of more than 3 MPa in up to 1% of the total area at various locations from several hundred micrometers to 1 mm in diameter. We believe that this full-field experimental method can be useful in GDM material and process development to reduce the local hard spots and help to mitigate the membrane shorting failure in PEM fuel cells.

Relationship between x-ray illumination field size and flat field intensity and its impacts on x-ray imaging

International Nuclear Information System (INIS)

Dong Xue; Niu Tianye; Jia Xun; Zhu Lei

2012-01-01

Purpose: X-ray cone-beam CT (CBCT) is being increasingly used for various clinical applications, while its performance is still hindered by image artifacts. This work investigates a new source of reconstruction error, which is often overlooked in the current CBCT imaging. The authors find that the x-ray flat field intensity (I 0 ) varies significantly as the illumination volume size changes at different collimator settings. A wrong I 0 value leads to inaccurate CT numbers of reconstructed images as well as wrong scatter measurements in the CBCT research. Methods: The authors argue that the finite size of x-ray focal spot together with the detector glare effect cause the I 0 variation at different illumination sizes. Although the focal spot of commercial x-ray tubes typically has a nominal size of less than 1 mm, the off-focal-spot radiation covers an area of several millimeters on the tungsten target. Due to the large magnification factor from the field collimator to the detector, the penumbra effects of the collimator blades result in different I 0 values for different illumination field sizes. Detector glare further increases the variation, since one pencil beam of incident x-ray is scattered into an area of several centimeters on the detector. In this paper, the authors study these two effects by measuring the focal spot distribution with a pinhole assembly and the detector point spread function (PSF) with an edge-spread function method. The authors then derive a formula to estimate the I 0 value for different illumination field sizes, using the measured focal spot distribution and the detector PSF. Phantom studies are carried out to investigate the accuracy of scatter measurements and CT images with and without considering the I 0 variation effects. Results: On our tabletop system with a Varian Paxscan 4030CB flat-panel detector and a Varian RAD-94 x-ray tube as used on a clinical CBCT system, the focal spot distribution has a measured full

Near-field Spectroscopy of Surface Plasmons in Flat Gold Nanoparticles

International Nuclear Information System (INIS)

Achermann, Marc; Shuford, Kevin L.; Schatz, George C.; Dahanayaka, D.H.; Bumm, Lloyd A; Klimov, Victor I.

2007-01-01

We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to study local surface plasmon resonances in flat gold nanoparticles (FGNPs). Depending on nanoparticle dimensions, local near-field extinction spectra exhibit none, one, or two resonances in the range of visible wavelengths (1.6-2.6 eV). The measured spectra can be accurately described in terms of interference between the field emitted by the probe aperture and the field reradiated by driven FGNP surface plasmon oscillations. The measured resonances are in good agreement with those predicted by calculations using discrete dipole approximation. We observe that the amplitudes of these resonances are dependent upon the spatial position of the near-field probe, which indicates the possibility of spatially selective excitation of specific plasmon modes

Experimental vibroacoustic testing of plane panels using synthesized random pressure fields.

Science.gov (United States)

Robin, Olivier; Berry, Alain; Moreau, Stéphane

2014-06-01

The experimental reproduction of random pressure fields on a plane panel and corresponding induced vibrations is studied. An open-loop reproduction strategy is proposed that uses the synthetic array concept, for which a small array element is moved to create a large array by post-processing. Three possible approaches are suggested to define the complex amplitudes to be imposed to the reproduction sources distributed on a virtual plane facing the panel to be tested. Using a single acoustic monopole, a scanning laser vibrometer and a baffled simply supported aluminum panel, experimental vibroacoustic indicators such as the Transmission Loss for Diffuse Acoustic Field, high-speed subsonic and supersonic Turbulent Boundary Layer excitations are obtained. Comparisons with simulation results obtained using a commercial software show that the Transmission Loss estimation is possible under both excitations. Moreover and as a complement to frequency domain indicators, the vibroacoustic behavior of the panel can be studied in the wave number domain.

Recommendations for Longitudinal Post-Tensioning in Full-Depth Precast Concrete Bridge Deck Panels

OpenAIRE

Bowers, Susan Elizabeth

2007-01-01

Full-depth precast concrete panels offer an efficient alternative to traditional cast-in-place concrete for replacement or new construction of bridge decks. Research has shown that longitudinal post-tensioning helps keep the precast bridge deck in compression and avoid problems such as leaking, cracking, spalling, and subsequent rusting on the beams at the transverse panel joints. Current design recommendations suggest levels of initial compression for precast concrete decks in a very limit...

Ultra-high resolution flat-panel volume CT: fundamental principles, design architecture, and system characterization

International Nuclear Information System (INIS)

Gupta, Rajiv; Brady, Tom; Grasruck, Michael; Suess, Christoph; Schmidt, Bernhard; Stierstorfer, Karl; Popescu, Stefan; Flohr, Thomas; Bartling, Soenke H.

2006-01-01

Digital flat-panel-based volume CT (VCT) represents a unique design capable of ultra-high spatial resolution, direct volumetric imaging, and dynamic CT scanning. This innovation, when fully developed, has the promise of opening a unique window on human anatomy and physiology. For example, the volumetric coverage offered by this technology enables us to observe the perfusion of an entire organ, such as the brain, liver, or kidney, tomographically (e.g., after a transplant or ischemic event). By virtue of its higher resolution, one can directly visualize the trabecular structure of bone. This paper describes the basic design architecture of VCT. Three key technical challenges, viz., scatter correction, dynamic range extension, and temporal resolution improvement, must be addressed for successful implementation of a VCT scanner. How these issues are solved in a VCT prototype and the modifications necessary to enable ultra-high resolution volumetric scanning are described. The fundamental principles of scatter correction and dose reduction are illustrated with the help of an actual prototype. The image quality metrics of this prototype are characterized and compared with a multi-detector CT (MDCT). (orig.)

Ultra-high resolution flat-panel volume CT: fundamental principles, design architecture, and system characterization

Energy Technology Data Exchange (ETDEWEB)

Gupta, Rajiv; Brady, Tom [Massachusetts General Hospital, Department of Radiology, Founders House, FND-2-216, Boston, MA (United States); Grasruck, Michael; Suess, Christoph; Schmidt, Bernhard; Stierstorfer, Karl; Popescu, Stefan; Flohr, Thomas [Siemens Medical Solutions, Forchheim (Germany); Bartling, Soenke H. [Hannover Medical School, Department of Neuroradiology, Hannover (Germany)

2006-06-15

Digital flat-panel-based volume CT (VCT) represents a unique design capable of ultra-high spatial resolution, direct volumetric imaging, and dynamic CT scanning. This innovation, when fully developed, has the promise of opening a unique window on human anatomy and physiology. For example, the volumetric coverage offered by this technology enables us to observe the perfusion of an entire organ, such as the brain, liver, or kidney, tomographically (e.g., after a transplant or ischemic event). By virtue of its higher resolution, one can directly visualize the trabecular structure of bone. This paper describes the basic design architecture of VCT. Three key technical challenges, viz., scatter correction, dynamic range extension, and temporal resolution improvement, must be addressed for successful implementation of a VCT scanner. How these issues are solved in a VCT prototype and the modifications necessary to enable ultra-high resolution volumetric scanning are described. The fundamental principles of scatter correction and dose reduction are illustrated with the help of an actual prototype. The image quality metrics of this prototype are characterized and compared with a multi-detector CT (MDCT). (orig.)

The Electromagnetic Zero-Point Field and the Flat Polarizable Vacuum Representation

CERN Document Server

Desiato, J T

2003-01-01

There are several interpretations of the Polarizable Vacuum (PV). One is the variable speed of light (VSL) approach, that has been shown to be isomorphic to General Relativity (GR) within experimental limits. However, another interpretation is representative of flat geometry, in which intervals of time and distance are measured in local inertial reference frames where the speed of light remains constant. The Flat PV approach leads to variable impedance transformations, governed by the spectral energy content of the Quantum Vacuum’s Electromagnetic (EM) Zero-Point Field (ZPF). The EM ZPF consists of photons. An unlimited number of photons may occupy the same quantum state at an arbitrary set of coordinates. Therefore, the spectral energy of the ZPF may be varied smoothly, represented by a superposition of EM waves with a large number of photons per cubic wavelength. Utilizing the Flat PV representation, a family of frequency dependent solutions of Poisson’s equation are derived, that may be applied as tool...

Noise, sampling, and the number of projections in cone-beam CT with a flat-panel detector

International Nuclear Information System (INIS)

Zhao, Z.; Gang, G. J.; Siewerdsen, J. H.

2014-01-01

Purpose: To investigate the effect of the number of projection views on image noise in cone-beam CT (CBCT) with a flat-panel detector. Methods: This fairly fundamental consideration in CBCT system design and operation was addressed experimentally (using a phantom presenting a uniform medium as well as statistically motivated “clutter”) and theoretically (using a cascaded systems model describing CBCT noise) to elucidate the contributing factors of quantum noise (σ Q ), electronic noise (σ E ), and view aliasing (σ view ). Analysis included investigation of the noise, noise-power spectrum, and modulation transfer function as a function of the number of projections (N proj ), dose (D tot ), and voxel size (b vox ). Results: The results reveal a nonmonotonic relationship between image noise andN proj at fixed total dose: for the CBCT system considered, noise decreased with increasing N proj due to reduction of view sampling effects in the regime N proj proj due to increased electronic noise. View sampling effects were shown to depend on the heterogeneity of the object in a direct analytical relationship to power-law anatomical clutter of the form κ/f  β —and a general model of individual noise components (σ Q , σ E , and σ view ) demonstrated agreement with measurements over a broad range in N proj , D tot , and b vox . Conclusions: The work elucidates fairly basic elements of CBCT noise in a manner that demonstrates the role of distinct noise components (viz., quantum, electronic, and view sampling noise). For configurations fairly typical of CBCT with a flat-panel detector (FPD), the analysis reveals a “sweet spot” (i.e., minimum noise) in the rangeN proj ∼ 250–350, nearly an order of magnitude lower in N proj than typical of multidetector CT, owing to the relatively high electronic noise in FPDs. The analysis explicitly relates view aliasing and quantum noise in a manner that includes aspects of the object (“clutter”) and imaging chain

Solid-state, flat-panel, digital radiography detectors and their physical imaging characteristics

Energy Technology Data Exchange (ETDEWEB)

Cowen, A.R. [LXi Research, Academic Unit of Medical Physics, University of Leeds, West Yorkshire (United Kingdom)], E-mail: a.r.cowen@leeds.ac.uk; Kengyelics, S.M.; Davies, A.G. [LXi Research, Academic Unit of Medical Physics, University of Leeds, West Yorkshire (United Kingdom)

2008-05-15

Solid-state, digital radiography (DR) detectors, designed specifically for standard projection radiography, emerged just before the turn of the millennium. This new generation of digital image detector comprises a thin layer of x-ray absorptive material combined with an electronic active matrix array fabricated in a thin film of hydrogenated amorphous silicon (a-Si:H). DR detectors can offer both efficient (low-dose) x-ray image acquisition plus on-line readout of the latent image as electronic data. To date, solid-state, flat-panel, DR detectors have come in two principal designs, the indirect-conversion (x-ray scintillator-based) and the direct-conversion (x-ray photoconductor-based) types. This review describes the underlying principles and enabling technologies exploited by these designs of detector, and evaluates their physical imaging characteristics, comparing performance both against each other and computed radiography (CR). In standard projection radiography indirect conversion DR detectors currently offer superior physical image quality and dose efficiency compared with direct conversion DR and modern point-scan CR. These conclusions have been confirmed in the findings of clinical evaluations of DR detectors. Future trends in solid-state DR detector technologies are also briefly considered. Salient innovations include WiFi-enabled, portable DR detectors, improvements in x-ray absorber layers and developments in alternative electronic media to a-Si:H.

Flat-detector computed tomography in diagnostic and interventional neuroradiology

International Nuclear Information System (INIS)

Struffert, T.; Doerfler, A.

2009-01-01

Originally aimed at improving standard radiography by providing higher absorption efficiency and a wider dynamic range than available with film-screen and phosphor luminescence, radiography flat detector technology is now widely accepted for neuroangiographic imaging. Especially flat-detector computed tomography (FD-CT), which uses rotational C-arm mounted flat-panel detector technology, is capable of volumetric imaging with a high spatial resolution. As ''angiographic CT'' FD-CT may be helpful in many diagnostic and neurointerventional procedures, e.g. intracranial stenting for cerebrovascular stenoses, stent-assisted coil embolization of wide-necked cerebral aneurysms and embolization of arteriovenous malformations. By providing morphologic, CT-like images of the brain within the angiography suite FD-CT allows rapid visualization of periprocedural hemorrhaging and may thus improve rapid complication management without the need of patient transfer. In addition, myelography and postmyelographic FD-CT imaging can be carried out using a single modality. Spinal interventions, such as kyphoplasty or vertebroplasty might also benefit from FD-CT. Imaging of the temporal bone may also develop into an important field of FD-CT. This paper briefly reviews the technical principles of FD technology and the potential applications in diagnostic and interventional neuroradiology. (orig.) [de

Prediction of the niche effect for single flat panels with or without attached sound absorbing materials.

Science.gov (United States)

Sgard, Franck; Atalla, Noureddine; Nélisse, Hugues

2015-01-01

The sound transmission loss (STL) of a test sample measured in sound transmission facilities is affected by the opening in which it is located. This is called the niche effect. This paper uses a modal approach to study the STL of a rectangular plate with or without an attached porous material located inside a box-shaped niche. The porous material is modeled as a limp equivalent fluid. The proposed model is validated by comparison with finite element/boundary element computations. Using a condensation of the pressure fields in the niche, the niche effect is interpreted in terms of a modification of the modal blocked pressure fields acting on the panel induced by the front cavity and by a modification of the radiation efficiency of the panel modes due to the presence of the back cavity. The modal approach is then used to investigate the impact of (1) the presence of a porous material attached to the panel on the niche effect and (2) the niche effect on the assessment of the porous material insertion loss. A simplified model for the porous material based on a transfer matrix approach is also proposed to predict the STL of the system and its validity is discussed.

Flat panel detector-based cone beam computed tomography with a circle-plus-two-arcs data acquisition orbit: Preliminary phantom study

International Nuclear Information System (INIS)

Ning Ruola; Tang Xiangyang; Conover, David; Yu Rongfeng

2003-01-01

Cone beam computed tomography (CBCT) has been investigated in the past two decades due to its potential advantages over a fan beam CT. These advantages include (a) great improvement in data acquisition efficiency, spatial resolution, and spatial resolution uniformity, (b) substantially better utilization of x-ray photons generated by the x-ray tube compared to a fan beam CT, and (c) significant advancement in clinical three-dimensional (3D) CT applications. However, most studies of CBCT in the past are focused on cone beam data acquisition theories and reconstruction algorithms. The recent development of x-ray flat panel detectors (FPD) has made CBCT imaging feasible and practical. This paper reports a newly built flat panel detector-based CBCT prototype scanner and presents the results of the preliminary evaluation of the prototype through a phantom study. The prototype consisted of an x-ray tube, a flat panel detector, a GE 8800 CT gantry, a patient table and a computer system. The prototype was constructed by modifying a GE 8800 CT gantry such that both a single-circle cone beam acquisition orbit and a circle-plus-two-arcs orbit can be achieved. With a circle-plus-two-arcs orbit, a complete set of cone beam projection data can be obtained, consisting of a set of circle projections and a set of arc projections. Using the prototype scanner, the set of circle projections were acquired by rotating the x-ray tube and the FPD together on the gantry, and the set of arc projections were obtained by tilting the gantry while the x-ray tube and detector were at the 12 and 6 o'clock positions, respectively. A filtered backprojection exact cone beam reconstruction algorithm based on a circle-plus-two-arcs orbit was used for cone beam reconstruction from both the circle and arc projections. The system was first characterized in terms of the linearity and dynamic range of the detector. Then the uniformity, spatial resolution and low contrast resolution were assessed using

Assessment of electromagnetic fields intensity emitted by cellular phone base stations in surrounding flats - a preliminary study

International Nuclear Information System (INIS)

Zmyslony, M.; Politanski, P.; Mamrot, P.; Bortkiewicz, A.

2006-01-01

A rapid development of mobile telecommunications (MT) has resulted in an increased concern about possible detrimental health effects of electromagnetic fields (EMFs) emitted by MT systems, and by MT base stations in particular. Research into EMFs effects on the health of inhabitants living in their vicinity requires first of all a solid assessment of the exposure level. Up to now, the reports in this field have been rather scant. This article presents the results of preliminary measurements of EMFs fields in selected flats around selected base stations in the city of Lodz. Measurements of electric field strength, E, to assess EMF exposure were based on the standard procedures currently in force in Poland. As the study is regarded as a preliminary one, the measurements were conducted in buildings with the expected largest radiation. The measurements show that in the flats located up to 500 m from the base station, EMFs are within the limits specified by relevant Polish regulations on the general public and environmental protection. It was also observed that in a few (less than 10%) flats the field with E exceeded 0.8 V/m. The results show that there are no correlations between electric field strength and distance between the flat and the base station. Therefore, the distance from the base station cannot be used to represent the exposure rate; to determine the latter, EMF measurements are necessary. (author)

Flat-detector computed tomography (FD-CT)

International Nuclear Information System (INIS)

Kalender, Willi A.; Kyriakou, Yiannis

2007-01-01

Flat-panel detectors or, synonymously, flat detectors (FDs) have been developed for use in radiography and fluoroscopy with the defined goal to replace standard X-ray film, film-screen combinations and image intensifiers by an advanced sensor system. FD technology in comparison to X-ray film and image intensifiers offers higher dynamic range, dose reduction, fast digital readout and the possibility for dynamic acquisitions of image series, yet keeping to a compact design. It appeared logical to employ FD designs also for computed tomography (CT) imaging. Respective efforts date back a few years only, but FD-CT has meanwhile become widely accepted for interventional and intra-operative imaging using C-arm systems. FD-CT provides a very efficient way of combining two-dimensional (2D) radiographic or fluoroscopic and 3D CT imaging. In addition, FD technology made its way into a number of dedicated CT scanner developments, such as scanners for the maxillo-facial region or for micro-CT applications. This review focuses on technical and performance issues of FD technology and its full range of applications for CT imaging. A comparison with standard clinical CT is of primary interest. It reveals that FD-CT provides higher spatial resolution, but encompasses a number of disadvantages, such as lower dose efficiency, smaller field of view and lower temporal resolution. FD-CT is not aimed at challenging standard clinical CT as regards to the typical diagnostic examinations; but it has already proven unique for a number of dedicated CT applications, offering distinct practical advantages, above all the availability of immediate CT imaging in the interventional suite or the operating room. (orig.)

Stationary vacuum fields with a conformally flat three-space Pt. 1

International Nuclear Information System (INIS)

Lukacs, B.; Perjes, Z.; Sebestyen, A.; Sparling, G.A.J.

1982-01-01

A generalized notion of conformastat space-times is introduced in relativity theory. In this sense, the conformastat space-time is stationary with the three-space of time-like Killing trajectories being conformally flat. A 3+1 decomposition of the field equations is given, and two classes of nonstatic conformastat vacuum fields are exhaustively investigated. The resulting three metrics form a NUT-type extension of the solution of the static conformastat vacuum problem. The authors conjecture that all conformastat vacuum space-times are axially symmetric. (author)

Full-Color LCD Microdisplay System Based on OLED Backlight Unit and Field-Sequential Color Driving Method

Directory of Open Access Journals (Sweden)

Sungho Woo

2011-01-01

Full Text Available We developed a single-panel LCD microdisplay system using a field-sequential color (FSC driving method and an organic light-emitting diode (OLED as a backlight unit (BLU. The 0.76′′ OLED BLU with red, green, and blue (RGB colors was fabricated by a conventional UV photolithography patterning process and by vacuum deposition of small molecule organic layers. The field-sequential driving frequency was set to 255 Hz to allow each of the RGB colors to be generated without color mixing at the given display frame rate. A prototype FSC LCD microdisplay system consisting of a 0.7′′ LCD microdisplay panel and the 0.76′′ OLED BLU successfully exhibited color display and moving picture images using the FSC driving method.

Atomically flat superconducting nanofilms: multiband properties and mean-field theory

Science.gov (United States)

Shanenko, A. A.; Aguiar, J. Albino; Vagov, A.; Croitoru, M. D.; Milošević, M. V.

2015-05-01

Recent progress in materials synthesis enabled fabrication of superconducting atomically flat single-crystalline metallic nanofilms with thicknesses down to a few monolayers. Interest in such nano-thin systems is attracted by the dimensional 3D-2D crossover in their coherent properties which occurs with decreasing the film thickness. The first fundamental aspect of this crossover is dictated by the Mermin-Wagner-Hohenberg theorem and concerns frustration of the long-range order due to superconductive fluctuations and the possibility to track its impact with an unprecedented level of control. The second important aspect is related to the Fabri-Pérot modes of the electronic motion strongly bound in the direction perpendicular to the nanofilm. The formation of such modes results in a pronounced multiband structure that changes with the nanofilm thickness and affects both the mean-field behavior and superconductive fluctuations. Though the subject is very rich in physics, it is scarcely investigated to date. The main obstacle is that there are no manageable models to study a complex magnetic response in this case. Full microscopic consideration is rather time consuming, if practicable at all, while the standard Ginzburg-Landau theory is not applicable. In the present work we review the main achievements in the subject to date, and construct and justify an efficient multiband mean-field formalism which allows for numerical and even analytical treatment of nano-thin superconductors in applied magnetic fields.

Atomically flat superconducting nanofilms: multiband properties and mean-field theory

International Nuclear Information System (INIS)

Shanenko, A A; Aguiar, J Albino; Vagov, A; Croitoru, M D; Milošević, M V

2015-01-01

Recent progress in materials synthesis enabled fabrication of superconducting atomically flat single-crystalline metallic nanofilms with thicknesses down to a few monolayers. Interest in such nano-thin systems is attracted by the dimensional 3D–2D crossover in their coherent properties which occurs with decreasing the film thickness. The first fundamental aspect of this crossover is dictated by the Mermin–Wagner–Hohenberg theorem and concerns frustration of the long-range order due to superconductive fluctuations and the possibility to track its impact with an unprecedented level of control. The second important aspect is related to the Fabri–Pérot modes of the electronic motion strongly bound in the direction perpendicular to the nanofilm. The formation of such modes results in a pronounced multiband structure that changes with the nanofilm thickness and affects both the mean-field behavior and superconductive fluctuations. Though the subject is very rich in physics, it is scarcely investigated to date. The main obstacle is that there are no manageable models to study a complex magnetic response in this case. Full microscopic consideration is rather time consuming, if practicable at all, while the standard Ginzburg–Landau theory is not applicable. In the present work we review the main achievements in the subject to date, and construct and justify an efficient multiband mean-field formalism which allows for numerical and even analytical treatment of nano-thin superconductors in applied magnetic fields. (paper)

Comparison of dose and image quality of a Flat-panel detector and an image intensifier; Comparacao da dose e qualidade da imagem de um detector Flatpanel e um intensificador de imagem

Energy Technology Data Exchange (ETDEWEB)

Lazzaro, M.; Friedrich, B.Q.; Luz, R.M. da; Silva, A.M.M. da, E-mail: marcos.lazzaro@acad.pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil)

2016-07-01

With the development of new technologies, have emerged new conversion methods of X-ray image, such as flat panel detectors. The aim of this work is the comparison of entrance surface air kerma (ESAK) and image quality between an image intensifier type of detector (A) and a flat panel (B). The ESAK was obtained by placing a ionization chamber under PMMA simulators of 10, 20 and 30 cm and the image quality was obtained by using the TOR {sup 18}FG simulator. The ESAK to the equipment A is higher when compared to the equipment B. The high contrast resolution is better for the equipment A for all thicknesses of simulators. The equipment A has low contrast resolution with a better viewing threshold for thicknesses of 10 and 20 cm, and a worse performance for 30 cm. It is concluded that the equipment B has ESAK smaller and despite having lower resolution, in almost all cases, have appropriate image quality for diagnosis. (author)

An experimental and theoretical study of new phosphors for full color field emission displays

Science.gov (United States)

Zhang, Fu-Li

An in depth study is reported of the cathodoluminescent (CL) properties of three new highly efficiency blue phosphors for field emission display (FED) applications doped with fast activators. The superior performance of a new Eu-doped green SrGa2S4 will also be reported. This work addresses four main topics: (1) a detailed study of the dependence of the luminescent intensity on activator concentration, as a function of electron beam voltage and current density; (2) the optical properties of thew phosphors and the development of a CL efficiency characterization technique using a critical screen weight method, which can obtain maximum light output and improve measurement accuracy; (3) understanding the low voltage CL mechanism associated with nanocrystal size by developing a thin film and disk model based on transportation theory and experimental results; (4) Development of a comprehensive evaluation method of red, green, and blue (RGB) phosphors for full color displays by calculation of luminance ratios, required luminance, and measurements of spectra, efficiency and saturation behavior. For FEDs which combine the best properties of CRT and flat panel displays, the development of efficient phosphors at low voltages and high current densities is shown to be critical to meet the luminance and power requirement demands for portable displays. Of particular importance is the need for a good blue phosphor, and to understand the dependence of the CL efficiency on nanocrystal size, penetration depth, diffusion length and surface recombination rate. This has been obtained from the thin film and disk models and fits to experiment. Comparisons between full color phosphor sets show that the performance of a display can vary by over a factor of three depending on the choice of the RGB set. Other factors that are important for optimizing the performance of FED phosphors are reviewed.

Cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS flat panel detector: visibility of simulated microcalcifications.

Science.gov (United States)

Shen, Youtao; Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C

2013-10-01

To measure and investigate the improvement of microcalcification (MC) visibility in cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS/CsI flat panel detector (Dexela 2923, Perkin Elmer). Aluminum wires and calcium carbonate grains of various sizes were embedded in a paraffin cylinder to simulate imaging of calcifications in a breast. Phantoms were imaged with a benchtop experimental cone beam CT system at various exposure levels. In addition to the Dexela detector, a high pitch (50 μm), thin (150 μm) scintillator CMOS/CsI flat panel detector (C7921CA-09, Hamamatsu Corporation, Hamamatsu City, Japan) and a widely used low pitch (194 μm), thick (600 μm) scintillator aSi/CsI flat panel detector (PaxScan 4030CB, Varian Medical Systems) were also used in scanning for comparison. The images were independently reviewed by six readers (imaging physicists). The MC visibility was quantified as the fraction of visible MCs and measured as a function of the estimated mean glandular dose (MGD) level for various MC sizes and detectors. The modulation transfer functions (MTFs) and detective quantum efficiencies (DQEs) were also measured and compared for the three detectors used. The authors have demonstrated that the use of a high pitch (75 μm) CMOS detector coupled with a thick (500 μm) CsI scintillator helped make the smaller 150-160, 160-180, and 180-200 μm MC groups more visible at MGDs up to 10.8, 9, and 10.8 mGy, respectively. It also made the larger 200-212 and 212-224 μm MC groups more visible at MGDs up to 7.2 mGy. No performance improvement was observed for 224-250 μm or larger size groups. With the higher spatial resolution of the Dexela detector based system, the apparent dimensions and shapes of MCs were more accurately rendered. The results show that with the aforementioned detector, a 73% visibility could be achieved in imaging 160-180 μm MCs as compared to 28% visibility achieved by the low pitch (194 μm) aSi/CsI flat

Source strength verification and quality assurance of preloaded brachytherapy needles using a CMOS flat panel detector

Energy Technology Data Exchange (ETDEWEB)

Golshan, Maryam, E-mail: maryam.golshan@bccancer.bc.ca [Department of Physics, University of British Columbia, Vancouver, British Columbia V6T1Z1, Canada and Department of Medical Physics, Vancouver Center, British Columbia Cancer Agency, Vancouver, British Columbia V5Z 4E6 (Canada); Spadinger, Ingrid [Department of Medical Physics, Vancouver Center, British Columbia Cancer Agency, Vancouver, British Columbia V5Z 4E6 (Canada); Chng, Nick [Department of Medical Physics, Center for the North, British Columbia Cancer Agency, Prince George, British Columbia V2M 7E9 (Canada)

2016-06-15

Purpose: Current methods of low dose rate brachytherapy source strength verification for sources preloaded into needles consist of either assaying a small number of seeds from a separate sample belonging to the same lot used to load the needles or performing batch assays of a subset of the preloaded seed trains. Both of these methods are cumbersome and have the limitations inherent to sampling. The purpose of this work was to investigate an alternative approach that uses an image-based, autoradiographic system capable of the rapid and complete assay of all sources without compromising sterility. Methods: The system consists of a flat panel image detector, an autoclavable needle holder, and software to analyze the detected signals. The needle holder was designed to maintain a fixed vertical spacing between the needles and the image detector, and to collimate the emissions from each seed. It also provides a sterile barrier between the needles and the imager. The image detector has a sufficiently large image capture area to allow several needles to be analyzed simultaneously.Several tests were performed to assess the accuracy and reproducibility of source strengths obtained using this system. Three different seed models (Oncura 6711 and 9011 {sup 125}I seeds, and IsoAid Advantage {sup 103}Pd seeds) were used in the evaluations. Seeds were loaded into trains with at least 1 cm spacing. Results: Using our system, it was possible to obtain linear calibration curves with coverage factor k = 1 prediction intervals of less than ±2% near the centre of their range for the three source models. The uncertainty budget calculated from a combination of type A and type B estimates of potential sources of error was somewhat larger, yielding (k = 1) combined uncertainties for individual seed readings of 6.2% for {sup 125}I 6711 seeds, 4.7% for {sup 125}I 9011 seeds, and 11.0% for Advantage {sup 103}Pd seeds. Conclusions: This study showed that a flat panel detector dosimetry system

A new system for fully automatic inspection of digital flat-panel detector radiographs of aluminium castings

International Nuclear Information System (INIS)

Fuchs, T.; Hassler, U.; Huetten, U.; Wenzel, T.

2006-01-01

The aim of our work was the integration of various newly-developed methods into a system for fully automatic radioscopic inspection of arbitrary casting parts. Using a 16-bit flat-panel detector, projections in arbitrary directions through the part are acquired and analysed. The software tool for inspection can be separated into five stages: registration, calibration, image processing, fault segmentation, and quality assessment. Thereby, each step is realized with full 16-bit data processing. Within the first processing stage, information about the physical length and density of the aluminium structures is extracted from the primary projections. Next, the primary image is registered with a reference image, which was acquired previously. Afterwards, the third stage combines both reference image-based and reference-less testing. A filter is applied, which adapts automatically to the local object structure by referring to the properties of the reference. Thereby, the self-adapting filter selects its size, direction and filter method optimally according to the local situation. Similar to the reference-less procedure, a subtraction is followed by a threshold operation, resulting in a map of regions that are suspected to be faulty. The fourth step aims at an elimination of false-positive detections. Again, two methods are applied successively: evaluation of local image features at suspicious positions and a classification based on teachings independent of position and orientation of the faults. Within the last step the quality criteria are applied. These criteria may concern fault size and depth, the density of faults in critical regions and a minimum distance between two or more faults. (orig.)

An Approximate Solution to the Plastic Indentation of Circular Sandwich Panels

Science.gov (United States)

Xie, Z.

2018-05-01

The plastic indentation response of circular sandwich panels loaded by the flat end of a cylinder is investigated employing a velocity field model. Using the principles of virtual velocities and minimum work, an expression for the indenter load in relation to the indenter displacement and displacement field of the deformed face sheet is derived. The analytical solutions obtained are in good agreement with those found by simulations using the ABAQUS code. The radial tensile strain of the deformed face sheet and the ratio of energy absorption rate of the core to that of the face sheet are discussed.

Uniqueness of the Fock quantization of scalar fields in spatially flat cosmological spacetimes

Energy Technology Data Exchange (ETDEWEB)

Gomar, Laura Castelló [Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid (Spain); Cortez, Jerónimo [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico D.F. 04510 (Mexico); Blas, Daniel Martín-de; Marugán, Guillermo A. Mena [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Velhinho, José M., E-mail: laucaste@estumail.ucm.es, E-mail: jacq@ciencias.unam.mx, E-mail: daniel.martin@iem.cfmac.csic.es, E-mail: jvelhi@ubi.pt [Departamento de Física, Faculdade de Ciências, Universidade da Beira Interior, R. Marquês D' Ávila e Bolama, 6201-001 Covilhã (Portugal)

2012-11-01

We study the Fock quantization of scalar fields in (generically) time dependent scenarios, focusing on the case in which the field propagation occurs in –either a background or effective– spacetime with spatial sections of flat compact topology. The discussion finds important applications in cosmology, like e.g. in the description of test Klein-Gordon fields and scalar perturbations in Friedmann-Robertson-Walker spacetime in the observationally favored flat case. Two types of ambiguities in the quantization are analyzed. First, the infinite ambiguity existing in the choice of a Fock representation for the canonical commutation relations, understandable as the freedom in the choice of inequivalent vacua for a given field. Besides, in cosmological situations, it is customary to scale the fields by time dependent functions, which absorb part of the evolution arising from the spacetime, which is treated classically. This leads to an additional ambiguity, this time in the choice of a canonical pair of field variables. We show that both types of ambiguities are removed by the requirements of (a) invariance of the vacuum under the symmetries of the three-torus, and (b) unitary implementation of the dynamics in the quantum theory. In this way, one arrives at a unique class of unitarily equivalent Fock quantizations for the system. This result provides considerable robustness to the quantum predictions and renders meaningful the confrontation with observation.

Beyond the limits of present active matrix flat-panel imagers (AMFPIs) for diagnostic radiology

Science.gov (United States)

Antonuk, Larry E.; El-Mohri, Youcef; Jee, Kyung-Wook; Maolinbay, Manat; Nassif, Samer C.; Rong, Xiujiang; Siewerdsen, Jeffrey H.; Zhao, Qihua; Street, Robert A.

1999-05-01

A theoretical cascaded systems analysis of the performance limits of x-ray imagers based on thin-film, active matrix flat-panel technology is presented. This analysis specifically focuses upon an examination of the functional dependence of the detective quantum efficiency on exposure. While the DQE of AMFPI systems is relatively high at the large exposure levels associated with radiographic x-ray imaging, there is a significant decline in DQE with decreasing exposure over the medium and lower end of the exposure range associated with fluoroscopic imaging. This fall-off in DQE originates from the relatively large size of the additive noise of AMFPI systems compared to their overall system gain. Therefore, strategies to diminish additive noise and increase system gain should significantly improve performance. Potential strategies for noise reduction include the use of charge compensation lines while strategies for gain enhancement include continuous photodiodes, pixel amplification structures, or higher gain converters. The effect of the implementation of such strategies is examined for a variety for hypothetical imager configurations. Through the modeling of these configurations, such enhancements are shown to hold the potential of making low frequency DQE response large and essentially independent of exposure while greatly reducing the fall-off in DQE at higher spatial frequencies.

Dose reduction of radiographs of the pediatric pelvis for diagnosing hip dysplasia using a digital flat-panel detector system; Dosisreduktion bei Roentgenaufnahmen des kindlichen Beckenskelettes zur Diagnostik der Hueftgelenksdysplasie unter Verwendung eines digitalen Flachdetektorsystems

Energy Technology Data Exchange (ETDEWEB)

Ludwig, K.; Ahlers, K.; Kloska, S.; Vieth, V.; Meier, N.; Heindel, W. [Inst. fuer Klinische Radiologie, Westfaelische Wilhelms-Univ. Muenster (Germany); Sandmann, C.; Gosheger, G. [Orthopaedische Klinik, Westfaelische Wilhelms-Univ. Muenster (Germany)

2003-01-01

Purpose: To evaluate a possible dose reduction in pediatric pelvic radiographs in congenital hip dysplasia using a digital flat-panel system instead of a phosphor-storage system. Materials and Methods: During a six-month period, all pediatric patients referred for pelvic radiography for the evaluation of congenital hip dysplasia were randomely assigned to be examined by either a phosphor-storage system or a digital flat-panel system, whereby the latter system was operated with half the radiation dose. Thirty pairs of radiographs were assessed for the visibility of 16 anatomic details and for 5 orthopedic-radiographic measurements (5-point scale with 1 = excellent; three independent observers). The projection indices of Ball and Kommenda and of Toennis and Brunken were calculated for all radiographs. The Student's t-test was used to compare the flat-panel and the phosphor-storage radiographs for observers' assessments, patients' age and projection indices. Results: In a total of 7560 observations, the scores for the visibility of anatomic details and orthopedic-radiographic measurements were respectively 2.72 and 2.64 for the flat-panel system and 2.93 and 2.79 for the phosphor-storage system. No significant differences were found between both systems (p > 0.05) and between patient age and projection indices (p > 0.05). Conclusion: Pediatric pelvic radiographs can be obtained with a digital flat-panel system using half the radiation dose instead of a phosphor-storage system without sacrificing relevant information in the diagnosis of congenital hip dysplasia. (orig.) [German] Zielsetzung: Evaluation einer moeglichen Dosisreduktion bei kindlichen Beckenroentgenaufnahmen zur Diagnostik der Hueftgelenksdysplasie mit einem digitalen Flachdetektorsystem im Vergleich zu einem digitalen Speicherfoliensystem. Material und Methoden: Prospektiv wurden alle ueber einen Zeitraum von 6 Monaten zur Roentgenaufnahme des Beckenskelettes im Rahmen der Diagnostik der

Normalized glandular dose (DgN) coefficients for flat-panel CT breast imaging

International Nuclear Information System (INIS)

Thacker, Samta C; Glick, Stephen J

2004-01-01

The development of new digital mammography techniques such as dual-energy imaging, tomosynthesis and CT breast imaging will require investigation of optimal camera design parameters and optimal imaging acquisition parameters. In optimizing these acquisition protocols and imaging systems it is important to have knowledge of the radiation dose to the breast. This study presents a methodology for estimating the normalized glandular dose to the uncompressed breast using the geometry proposed for flat-panel CT breast imaging. The simulation uses the GEANT 3 Monte Carlo code to model x-ray transport and absorption within the breast phantom. The Monte Carlo software was validated for breast dosimetry by comparing results of the normalized glandular dose (DgN) values of the compressed breast to those reported in the literature. The normalized glandular dose was then estimated for a range of breast diameters from 10 cm to 18 cm using an uncompressed breast model with a homogeneous composition of adipose and glandular tissue, and for monoenergetic x-rays from 10 keV to 120 keV. These data were fit providing expressions for the normalized glandular dose. Using these expressions for the DgN coefficients and input variables such as the diameter, height and composition of the breast phantom, the mean glandular dose for any spectra can be estimated. A computer program to provide normalized glandular dose values has been made available online. In addition, figures displaying energy deposition maps are presented to better understand the spatial distribution of dose in CT breast imaging

Creation-field cosmology: A possible solution to singularity, horizon, and flatness problems

International Nuclear Information System (INIS)

Narlikar, J.V.; Padmanabhan, T.

1985-01-01

A solution of Einstein's equations which admits radiation and a negative-energy massless scalar creation field as a source is presented. It is shown that the cosmological model based on this solution satisfies all the observational tests and thus is a viable alternative to the standard big-bang model. The present model is free from singularity and particle horizon and provides a natural explanation for the flatness problem. We argue that these features make the creation-field cosmological model theoretically superior to the big-bang model

Design, Simulation and Experimental Investigation of a Solar System Based on PV Panels and PVT Collectors

Directory of Open Access Journals (Sweden)

Annamaria Buonomano

2016-06-01

Full Text Available This paper presents numerical and experimental analyses aimed at evaluating the technical and economic feasibility of photovoltaic/thermal (PVT collectors. An experimental setup was purposely designed and constructed in order to compare the electrical performance of a PVT solar field with the one achieved by an identical solar field consisting of conventional photovoltaic (PV panels. The experimental analysis also aims at evaluating the potential advantages of PVT vs. PV in terms of enhancement of electrical efficiency and thermal energy production. The installed experimental set-up includes four flat polycrystalline silicon PV panels and four flat unglazed polycrystalline silicon PVT collectors. The total electrical power and area of the solar field are 2 kWe and 13 m2, respectively. The experimental set-up is currently installed at the company AV Project Ltd., located in Avellino (Italy. This study also analyzes the system from a numerical point of view, including a thermo-economic dynamic simulation model for the design and the assessment of energy performance and economic profitability of the solar systems consisting of glazed PVT and PV collectors. The experimental setup was modelled and partly simulated in TRNSYS environment. The simulation model was useful to analyze efficiencies and temperatures reached by such solar technologies, by taking into account the reference technology of PVTs (consisting of glazed collectors as well as to compare the numerical data obtained by dynamic simulations with the gathered experimental results for the PV technology. The numerical analysis shows that the PVT global efficiency is about 26%. Conversely, from the experimental point of view, the average thermal efficiency of PVT collectors is around 13% and the electrical efficiencies of both technologies are almost coincident and equal to 15%.

The Usefulness of Three-Dimensional Angiography with a Flat Panel Detector of Direct Conversion Type in a Transcatheter Arterial Chemoembolization Procedure for Hepatocellular Carcinoma: Initial Experience

International Nuclear Information System (INIS)

Kakeda, Shingo; Korogi, Yukunori; Hatakeyama, Yoshihisa; Ohnari, Norihiro; Oda, Nobuhiro; Nishino, Kazuyoshi; Miyamoto, Wataru

2008-01-01

The purpose of this study was to assess the usefulness of a three-dimensional (3D) angiography system using a flat panel detector of direct conversion type in treatments with subsegmental transcatheter arterial chemoembolization (TACE) for hepatocellular carcinomas (HCCs). Thirty-six consecutive patients who underwent hepatic angiography were prospectively examined. First, two radiologists evaluated the degree of visualization of the peripheral branches of the hepatic arteries on 3D digital subtraction angiography (DSA). Then the radiologists evaluated the visualization of tumor staining and feeding arteries in 25 patients (30 HCCs) who underwent subsegmental TACE. The two radiologists who performed the TACE assessed whether the additional information provided by 3D DSA was useful for treatments. In 34 (94.4%) of 36 patients, the subsegmental branches of the hepatic arteries were sufficiently visualized. The feeding arteries of HCCs were sufficiently visualized in 28 (93%) of 30 HCCs, whereas tumor stains were sufficiently visualized in 18 (60%). Maximum intensity projection images were significantly superior to volume recording images for visualization of the tumor staining and feeding arteries of HCCs. In 27 (90%) of 30 HCCs, 3D DSA provided additional useful information for subsegmental TACE. The high-quality 3D DSA with flat panel detector angiography system provided a precise vascular road map, which was useful for performing subsegmental TACE .of HCCs

SU-E-J-45: The Correlation Between CBCT Flat Panel Misalignment and 3D Image Guidance Accuracy

International Nuclear Information System (INIS)

Kenton, O; Valdes, G; Yin, L; Teo, B; Brousmiche, S; Wikler, D

2015-01-01

Purpose To simulate the impact of CBCT flat panel misalignment on the image quality, the calculated correction vectors in 3D image guided proton therapy and to determine if these calibration errors can be caught in our QA process. Methods The X-ray source and detector geometrical calibration (flexmap) file of the CBCT system in the AdaPTinsight software (IBA proton therapy) was edited to induce known changes in the rotational and translational calibrations of the imaging panel. Translations of up to ±10 mm in the x, y and z directions (see supplemental) and rotational errors of up to ±3° were induced. The calibration files were then used to reconstruct the CBCT image of a pancreatic patient and CatPhan phantom. Correction vectors were calculated for the patient using the software’s auto match system and compared to baseline values. The CatPhan CBCT images were used for quantitative evaluation of image quality for each type of induced error. Results Translations of 1 to 3 mm in the x and y calibration resulted in corresponding correction vector errors of equal magnitude. Similar 10mm shifts were seen in the y-direction; however, in the x-direction, the image quality was too degraded for a match. These translational errors can be identified through differences in isocenter from orthogonal kV images taken during routine QA. Errors in the z-direction had no effect on the correction vector and image quality.Rotations of the imaging panel calibration resulted in corresponding correction vector rotations of the patient images. These rotations also resulted in degraded image quality which can be identified through quantitative image quality metrics. Conclusion Misalignment of CBCT geometry can lead to incorrect translational and rotational patient correction vectors. These errors can be identified through QA of the imaging isocenter as compared to orthogonal images combined with monitoring of CBCT image quality

Multiple-Panel Cylindrical Solar Concentrator

Science.gov (United States)

Brown, E. M.

1983-01-01

Trough composed of many panels concentrates Sun's energy on solar cells, even when trough is not pointed directly at Sun. Tolerates deviation as great as 5 degrees from direction of sun. For terrestrial applications, multiple-flat-plate design offers potential cost reduction and ease of fabrication.

Dynamic determination of modulus of elasticity of full-size wood composite panels using a vibration method

Science.gov (United States)

Cheng Guan; Houjiang Zhang; Lujing Zhou; Xiping Wang

2015-01-01

A vibration testing method based on free vibration theory in a ‘‘free–free” support condition was investigated for evaluating the modulus of elasticity (MOE) of full-size wood composite panels (WCPs). Vibration experiments were conducted on three types of WCPs (medium density fibreboard, particleboard, and plywood) to determine the dynamic MOE of the panels. Static...

Hydrogen production by the engineered cyanobacterial strain Nostoc PCC 7120 ΔhupW examined in a flat panel photobioreactor system.

Science.gov (United States)

Nyberg, Marcus; Heidorn, Thorsten; Lindblad, Peter

2015-12-10

Nitrogenase based hydrogen production was examined in a ΔhupW strain of the filamentous heterocystous cyanobacterium Nostoc PCC 7120, i.e., cells lacking the last step in the maturation system of the large subunit of the uptake hydrogenase and as a consequence with a non-functional uptake hydrogenase. The cells were grown in a developed flat panel photobioreactor system with 3.0L culture volume either aerobically (air) or anaerobically (Ar or 80% N2/20% Ar) and illuminated with a mixture of red and white LED. Aerobic growth of the ΔhupW strain of Nostoc PCC 7120 at 44μmolar photons m(-2)s(-1) PAR gave the highest hydrogen production of 0.7mL H2 L(-1)h(-1), 0.53mmol H2 mg chlorophyll a(-1)h(-1), and a light energy conversion efficiency of 1.2%. Anaerobic growth using 100% argon showed a maximal hydrogen production of 1.7mLL(-1)h(-1), 0.85mmol per mg chlorophyll a(-1) h(-1), and a light energy conversion efficiency of 2.7%. Altering between argon/N2 (20/80) and 100% argon phases resulted in a maximal hydrogen production at hour 128 (100% argon phase) with 6.2mL H2L(-1)h(-1), 0.71mL H2 mg chlorophyll a(-1)h(-1), and a light energy efficiency conversion of 4.0%. The highest buildup of hydrogen gas observed was 6.89% H2 (100% argon phase) of the total photobioreactor system with a maximal production of 4.85mL H2 L(-1)h(-1). The present study clearly demonstrates the potential to use purpose design cyanobacteria in developed flat panel photobioreactor systems for the direct production of the solar fuel hydrogen. Further improvements in the strain used, environmental conditions employed, and growth, production and collection systems used, are needed before a sustainable and economical cyanobacterial based hydrogen production can be realized. Copyright © 2015 Elsevier B.V. All rights reserved.

The Effect of Round Window vs Cochleostomy Surgical Approaches on Cochlear Implant Electrode Position: A Flat-Panel Computed Tomography Study.

Science.gov (United States)

Jiam, Nicole T; Jiradejvong, Patpong; Pearl, Monica S; Limb, Charles J

2016-09-01

The round window insertion (RWI) and cochleostomy approaches are the 2 most common surgical techniques used in cochlear implantation (CI). However, there is no consensus on which approach is ideal for electrode array insertion, in part because visualization of intracochlear electrode position is challenging, so postoperative assessment of intracochlear electrode contact is lacking. To measure and compare electrode array position between RWI and cochleostomy approaches for CI insertion. Retrospective case-comparison study of 17 CI users with Med-El standard-length electrode arrays who underwent flat-panel computed tomography scans after CI surgery at a tertiary referral center. The data was analyzed in October 2015. Flat-panel computed tomography scans were collected between January 1 and August 31, 2013, for 22 electrode arrays. The surgical technique was identified by a combination of operative notes and imaging. Eight cochleae underwent RWI and 14 cochleae underwent cochleostomy approaches anterior and inferior to the round window. Interscalar electrode position and electrode centroid distance to the osseous spiral lamina, lateral bony wall, and central axis of the modiolus. Nine participants were men, and 8, women; the mean age was 54.4 (range, 21-64) years. Electrode position was significantly closer to cochlear neural elements with RWI than cochleostomy approaches. Between the 2 surgical approaches, the RWI technique produced shorter distances between the electrode and the modiolus (mean difference, -0.33 [95% CI, -0.29 to -0.39] mm in the apical electrode; -1.42 [95% CI, -1.24 to -1.57] mm in the basal electrode). This difference, which was most prominent in the first third and latter third of the basal turn, decreased after the basal turn. The RWI approach was associated with an increased likelihood of perimodiolar placement. Opting to use RWI over cochleostomy approaches in CI candidates may position electrodes closer to cochlear neural substrates and

Transparent Fingerprint Sensor System for Large Flat Panel Display.

Science.gov (United States)

Seo, Wonkuk; Pi, Jae-Eun; Cho, Sung Haeung; Kang, Seung-Youl; Ahn, Seong-Deok; Hwang, Chi-Sun; Jeon, Ho-Sik; Kim, Jong-Uk; Lee, Myunghee

2018-01-19

In this paper, we introduce a transparent fingerprint sensing system using a thin film transistor (TFT) sensor panel, based on a self-capacitive sensing scheme. An armorphousindium gallium zinc oxide (a-IGZO) TFT sensor array and associated custom Read-Out IC (ROIC) are implemented for the system. The sensor panel has a 200 × 200 pixel array and each pixel size is as small as 50 μm × 50 μm. The ROIC uses only eight analog front-end (AFE) amplifier stages along with a successive approximation analog-to-digital converter (SAR ADC). To get the fingerprint image data from the sensor array, the ROIC senses a capacitance, which is formed by a cover glass material between a human finger and an electrode of each pixel of the sensor array. Three methods are reviewed for estimating the self-capacitance. The measurement result demonstrates that the transparent fingerprint sensor system has an ability to differentiate a human finger's ridges and valleys through the fingerprint sensor array.

On-axis and far-field sound radiation from resilient flat and dome-shaped radiators

NARCIS (Netherlands)

Aarts, R.M.; Janssen, A.J.E.M.

2009-01-01

On-axis and far-field series expansions are developed for the sound pressure due to an arbitrary, circular symmetric velocity distribution on a flat radiator in an infinite baffle. These expansions are obtained by expanding the velocity distributions in terms of orthogonal polynomials

Detection of Cement Leakage After Vertebroplasty with a Non-Flat-Panel Angio Unit Compared to Multidetector Computed Tomography - An Ex Vivo Study

International Nuclear Information System (INIS)

Baumann, Clemens; Fuchs, Heiko; Westphalen, Kerstin; Hierholzer, Johannes

2008-01-01

The purpose of this study was to investigate the detection of cement leakages after vertebroplasty using angiographic computed tomography (ACT) in a non-flat-panel angio unit compared to multidetector computed tomography (MDCT). Vertebroplasty was performed in 19 of 33 cadaver vertebrae (23 thoracic and 10 lumbar segments). In the angio suite, ACT (190 o ; 1.5 o per image) was performed to obtain volumetric data. Another volumetric data set of the specimen was obtained by MDCT using a standard algorithm. Nine multiplanar reconstructions in standardized axial, coronal, and sagittal planes of every vertebra were generated from both data sets. Images were evaluated on the basis of a nominal scale with 18 criteria, comprising osseous properties (e.g., integrity of the end plate) and cement distribution (e.g., presence of intraspinal cement). MDCT images were regarded as gold standard and analyzed by two readers in a consensus mode. Rotational acquisitions were analyzed by six blinded readers. Results were correlated with the gold standard using Cohen's κ-coefficient analysis. Furthermore, interobserver variability was calculated. Correlation with the gold standard ranged from no correlation (osseous margins of the neuroforamen, κ = 0.008) to intermediate (trace of vertebroplasty canula; κ = 0.615) for criteria referring to osseous morphology. However, there was an excellent correlation for those criteria referring to cement distribution, with κ values ranging from 0.948 (paravertebral cement distribution) to 0.972 (intraspinal cement distribution). With a minimum of κ = 0.768 ('good correlation') and a maximum of κ = 0.91 ('excellent'), interobserver variability was low. In conclusion, ACT in an angio suite without a flat-panel detector depicts a cement leakage after vertebroplasty as well as MDCT. However, the method does not provide sufficient depiction of osseous morphology.

Initial evaluation of a full breast digital system

International Nuclear Information System (INIS)

Vano, E.; Fernandez, J.M.; Chevalier, M.; Moran, P.; Cepeda, T.; Fabra, A.; Alvarez Pedrosa, C.S.

2001-01-01

Full-field digital mammography systems have been developed for overcoming the limitations of the screen-film mammography. This work is focused on the system from GE Medical Systems (Senographe 2000) which has been recently installed in our institution. The imager consists of a thin Ics:Tl scintillator which is in narrow contact with an array of amorphous silicon detectors mounted in a single panel. The flat-panel detector is integrated in a x-ray system with a high-frequency generator Senographe DM and dual track anode of Mo and Rh with Mo and Rh filtration. The aim of this work is to analyse the defaults exposure factors set at the installation of the x-ray unit. The image quality has been evaluated by using one of the two phantoms recommended in the ACR Accreditation Program. Phantom images were obtained at each of the three available imaging modes: contrast (CNT), standard (STD) and DOSE. While maintaining the defaults of kilovoltage and anode/filter combination, phantom images were obtained at lower dose vales. The contrast noise ratio (CNR) was calculated for each of the low contrast objects (masses) of the phantom images and the detail visibility was also evaluated. The results obtained for both parameters reveal that similar image quality can be obtained with significant reductions of the average glandular dose. (author)

Supersymmetric gauge theories, quantization of M{sub flat}, and conformal field theory

Energy Technology Data Exchange (ETDEWEB)

Teschner, J.; Vartanov, G.S.

2013-02-15

We propose a derivation of the correspondence between certain gauge theories with N=2 supersymmetry and conformal field theory discovered by Alday, Gaiotto and Tachikawa in the spirit of Seiberg-Witten theory. Based on certain results from the literature we argue that the quantum theory of the moduli spaces of flat SL(2,R)-connections represents a nonperturbative ''skeleton'' of the gauge theory, protected by supersymmetry. It follows that instanton partition functions can be characterized as solutions to a Riemann-Hilbert type problem. In order to solve it, we describe the quantization of the moduli spaces of flat connections explicitly in terms of two natural sets of Darboux coordinates. The kernel describing the relation between the two pictures represents the solution to the Riemann Hilbert problem, and is naturally identified with the Liouville conformal blocks.

Clinical investigation of flat panel CT following middle ear reconstruction: a study of 107 patients

Energy Technology Data Exchange (ETDEWEB)

Zaoui, K. [University Hospital Heidelberg, Ruprecht Karls University, Department of Otorhinolaryngology, Head and Neck Surgery, Heidelberg (Germany); Kromeier, J. [St. Josefs Hospital, RkK, Department of Radiology, Freiburg (Germany); Neudert, M.; Beleites, T.; Zahnert, T. [University Hospital Dresden, Technical University, Department of Otorhinolaryngology, Head and Neck Surgery, Dresden (Germany); Laszig, R.; Offergeld, C. [University Hospital Freiburg, Albert Ludwigs University, Department of Otorhinolaryngology, Head and Neck Surgery, Freiburg (Germany)

2014-03-15

After middle ear reconstruction using partial or total ossicular replacement prostheses (PORP/TORP), an air-bone gap (ABG) may persist because of prosthesis displacement or malposition. So far, CT of the temporal bone has played the main role in the diagnosis of reasons for postoperative insufficient ABG improvement. Recent experimental and clinical studies have evaluated flat panel CT (fpCT) as an alternative imaging technique that provides images with high isovolumetric resolution, fewer metal-induced artefacts and lower irradiation doses. One hundred and seven consecutive patients with chronic otitis media with or without cholesteatoma underwent reconstruction by PORP (n = 52) or TORP (n = 55). All subjects underwent preoperative and postoperative audiometric testing and postoperative fpCT. Statistical evaluation of all 107 patients as well as the sole sub-assembly groups (PORP or TORP) showed a highly significant correlation between hearing improvement and fpCT-determined prosthesis position. FpCT enables detailed postoperative information on patients with middle ear reconstruction. FpCT is a new imaging technique that provides immediate feedback on surgical results after reconstructive middle ear surgery. Specific parameters evaluated by fpCT may serve as a predictive tool for estimated postoperative hearing improvement. Therefore this imaging technique is suitable for postoperative quality control in reconstructive middle ear surgery. (orig.)

Development of CT and 3D-CT Using Flat Panel Detector Based Real-Time Digital Radiography System

International Nuclear Information System (INIS)

Ravindran, V. R.; Sreelakshmi, C.; Vibin

2008-01-01

The application of Digital Radiography in the Nondestructive Evaluation (NDE) of space vehicle components is a recent development in India. A Real-time DR system based on amorphous silicon Flat Panel Detector has been developed for the NDE of solid rocket motors at Rocket Propellant Plant of VSSC in a few years back. The technique has been successfully established for the nondestructive evaluation of solid rocket motors. The DR images recorded for a few solid rocket specimens are presented in the paper. The Real-time DR system is capable of generating sufficient digital X-ray image data with object rotation for the CT image reconstruction. In this paper the indigenous development of CT imaging based on the Realtime DR system for solid rocket motor is presented. Studies are also carried out to generate 3D-CT image from a set of adjacent CT images of the rocket motor. The capability of revealing the spatial location and characterisation of defect is demonstrated by the CT and 3D-CT images generated.

Semi-automatic classification of skeletal morphology in genetically altered mice using flat-panel volume computed tomography.

Directory of Open Access Journals (Sweden)

Christian Dullin

2007-07-01

Full Text Available Rapid progress in exploring the human and mouse genome has resulted in the generation of a multitude of mouse models to study gene functions in their biological context. However, effective screening methods that allow rapid noninvasive phenotyping of transgenic and knockout mice are still lacking. To identify murine models with bone alterations in vivo, we used flat-panel volume computed tomography (fpVCT for high-resolution 3-D imaging and developed an algorithm with a computational intelligence system. First, we tested the accuracy and reliability of this approach by imaging discoidin domain receptor 2- (DDR2- deficient mice, which display distinct skull abnormalities as shown by comparative landmark-based analysis. High-contrast fpVCT data of the skull with 200 microm isotropic resolution and 8-s scan time allowed segmentation and computation of significant shape features as well as visualization of morphological differences. The application of a trained artificial neuronal network to these datasets permitted a semi-automatic and highly accurate phenotype classification of DDR2-deficient compared to C57BL/6 wild-type mice. Even heterozygous DDR2 mice with only subtle phenotypic alterations were correctly determined by fpVCT imaging and identified as a new class. In addition, we successfully applied the algorithm to classify knockout mice lacking the DDR1 gene with no apparent skull deformities. Thus, this new method seems to be a potential tool to identify novel mouse phenotypes with skull changes from transgenic and knockout mice on the basis of random mutagenesis as well as from genetic models. However for this purpose, new neuronal networks have to be created and trained. In summary, the combination of fpVCT images with artificial neuronal networks provides a reliable, novel method for rapid, cost-effective, and noninvasive primary screening tool to detect skeletal phenotypes in mice.

Gain and offset calibration reduces variation in exposure-dependent SNR among systems with identical digital flat-panel detectors.

Science.gov (United States)

Willis, Charles E; Vinogradskiy, Yevgeniy Y; Lofton, Brad K; White, R Allen

2011-07-01

The conditions under which vendor performance criteria for digital radiography systems are obtained do not adequately simulate the conditions of actual clinical imaging with respect to radiographic technique factors, scatter production, and scatter control. Therefore, the relationship between performance under ideal conditions and performance in clinical practice remains unclear. Using data from a large complement of systems in clinical use, the authors sought to develop a method to establish expected performance criteria for digital flat-panel radiography systems with respect to signal-to-noise ratio (SNR) versus detector exposure under clinical conditions for thoracic imaging. The authors made radiographic exposures of a patient-equivalent chest phantom at 125 kVp and 180 cm source-to-image distance. The mAs value was modified to produce exposures above and below the mAs delivered by automatic exposure control. Exposures measured free-in-air were corrected to the imaging plane by the inverse square law, by the attenuation factor of the phantom, and by the Bucky factor of the grid for the phantom, geometry, and kilovolt peak. SNR was evaluated as the ratio of the mean to the standard deviation (SD) of a region of interest automatically selected in the center of each unprocessed image. Data were acquired from 18 systems, 14 of which were tested both before and after gain and offset calibration. SNR as a function of detector exposure was interpolated using a double logarithmic function to stratify the data into groups of 0.2, 0.5, 1.0, 2.0, and 5.0 mR exposure (1.8, 4.5, 9.0, 18, and 45 microGy air KERMA) to the detector. The mean SNR at each exposure interval after calibration exhibited linear dependence on the mean SNR before calibration (r2=0.9999). The dependence was greater than unity (m = 1.101 +/- 0.006), and the difference from unity was statistically significant (p grid replacement. The nonconformant behavior of the other system was corrected by replacing

A forward bias method for lag correction of an a-Si flat panel detector

International Nuclear Information System (INIS)

Starman, Jared; Tognina, Carlo; Partain, Larry; Fahrig, Rebecca

2012-01-01

Purpose: Digital a-Si flat panel (FP) x-ray detectors can exhibit detector lag, or residual signal, of several percent that can cause ghosting in projection images or severe shading artifacts, known as the radar artifact, in cone-beam computed tomography (CBCT) reconstructions. A major contributor to detector lag is believed to be defect states, or traps, in the a-Si layer of the FP. Software methods to characterize and correct for the detector lag exist, but they may make assumptions such as system linearity and time invariance, which may not be true. The purpose of this work is to investigate a new hardware based method to reduce lag in an a-Si FP and to evaluate its effectiveness at removing shading artifacts in CBCT reconstructions. The feasibility of a novel, partially hardware based solution is also examined. Methods: The proposed hardware solution for lag reduction requires only a minor change to the FP. For pulsed irradiation, the proposed method inserts a new operation step between the readout and data collection stages. During this new stage the photodiode is operated in a forward bias mode, which fills the defect states with charge. A Varian 4030CB panel was modified to allow for operation in the forward bias mode. The contrast of residual lag ghosts was measured for lag frames 2 and 100 after irradiation ceased for standard and forward bias modes. Detector step response, lag, SNR, modulation transfer function (MTF), and detective quantum efficiency (DQE) measurements were made with standard and forward bias firmware. CBCT data of pelvic and head phantoms were also collected. Results: Overall, the 2nd and 100th detector lag frame residual signals were reduced 70%-88% using the new method. SNR, MTF, and DQE measurements show a small decrease in collected signal and a small increase in noise. The forward bias hardware successfully reduced the radar artifact in the CBCT reconstruction of the pelvic and head phantoms by 48%-81%. Conclusions: Overall, the

Successful closure of treatment-naïve, flat edge (Type II, full-thickness macular hole using inverted internal limiting membrane flap technique

Directory of Open Access Journals (Sweden)

Hussain N

2016-10-01

Full Text Available Nazimul Hussain,1 Anjli Hussain2 1Department of Ophthalmology, Al Zahra Hospital, 2Al Zahra Medical Center, Dubai, United Arab Emirates Objective: The objective of this study was to present the outcome of the internal limiting membrane (ILM peeling flap technique for a treatment-naïve, flat edge (Type II, full-thickness macular hole (MH. Methods: A 52-year-old man presented with complaints of decreased vision and seeing black spot. He was diagnosed to have a flat edge, full-thickness MH, which was confirmed by optical coherence tomography (OCT. He underwent 23G vitrectomy with brilliant blue G-assisted inverted ILM peeling with an inverted flap over the hole followed by fluid gas exchange. Results: Postoperative follow-up until 3 months showed successful closure of the MH, which was confirmed by OCT. The best-corrected visual acuity improved from baseline 6/60 to 6/12 at the final follow-up. Conclusion: Using the inverted ILM flap technique, a treatment-naïve, flat edge (Type II, full thickness MH achieved successful anatomical and functional outcomes. Keywords: macular hole, inverted ILM, optical coherence tomography

A performance comparison of direct- and indirect-detection flat-panel imagers

International Nuclear Information System (INIS)

Partridge, M.; Hesse, B.-M.; Mueller, L.

2002-01-01

A comparison of the performance of a direct- and an indirect-detection amorphous silicon flat-panel X-ray imager is presented for a 6 MV beam. Experimental measurements of the noise characteristics, image lag, spectral response, spatial resolution and quantum efficiency are described, compared and discussed. The two systems are comprised of 512x512 pixel, 400 μm pitch, arrays of a-Si:H p-i-n photodiodes and thin-film transistors. In the direct-detection system, X-rays interact to produce electron/hole pairs directly in the silicon photodiodes. For the indirect-detection system, a phosphor screen converts energy from the incident X-rays into visible light, which is then detected by the photodiodes. Both systems are shown to be quantum noise limited, with the total electronic noise in the detector 10-15 times smaller than the Poisson noise level in detected signal. The measured lag for both systems is 1.0±0.1% or less in the first frame with subsequent signals decaying exponentially with frame read-out, with a half-life of between 3.3 and 3.8 frames. Both systems are demonstrated to have a pronounced sensitivity to low-energy multiply scattered photons, although this is shown to be effectively filtered out using a 2 mm copper build-up plate. The direct-detection system, with the 2 mm Cu build-up, shows greater sensitivity to scattered radiation than the indirect system. The spatial resolutions of both systems were effectively equal with an f 50 of 0.25 mm -1 when pixels are binned 2x2, although a slight contribution from optical scattering in the phosphor screen is seen for the indirect-detection system. The quantum efficiency of the direct-detection system is a factor of 0.45 lower than that of the indirect-detection system. The application of these detectors to megavoltage CT is discussed, with the conclusion that the indirect-detection system is to be preferred

The effect of air flow, panel curvature, and internal pressurization on field-incidence transmission loss. [acoustic propagation through aircraft fuselage

Science.gov (United States)

Koval, L. R.

1975-01-01

In the context of sound transmission through aircraft fuselage panels, equations for the field-incidence transmission loss (TL) of a single-walled panel are derived that include the effects of external air flow, panel curvature, and internal fuselage pressurization. These effects are incorporated into the classical equations for the TL of single panels, and the resulting double integral for field-incidence TL is numerically evaluated for a specific set of parameters.

A full-spectrum analysis of high-speed train interior noise under multi-physical-field coupling excitations

Science.gov (United States)

Zheng, Xu; Hao, Zhiyong; Wang, Xu; Mao, Jie

2016-06-01

High-speed-railway-train interior noise at low, medium, and high frequencies could be simulated by finite element analysis (FEA) or boundary element analysis (BEA), hybrid finite element analysis-statistical energy analysis (FEA-SEA) and statistical energy analysis (SEA), respectively. First, a new method named statistical acoustic energy flow (SAEF) is proposed, which can be applied to the full-spectrum HST interior noise simulation (including low, medium, and high frequencies) with only one model. In an SAEF model, the corresponding multi-physical-field coupling excitations are firstly fully considered and coupled to excite the interior noise. The interior noise attenuated by sound insulation panels of carriage is simulated through modeling the inflow acoustic energy from the exterior excitations into the interior acoustic cavities. Rigid multi-body dynamics, fast multi-pole BEA, and large-eddy simulation with indirect boundary element analysis are first employed to extract the multi-physical-field excitations, which include the wheel-rail interaction forces/secondary suspension forces, the wheel-rail rolling noise, and aerodynamic noise, respectively. All the peak values and their frequency bands of the simulated acoustic excitations are validated with those from the noise source identification test. Besides, the measured equipment noise inside equipment compartment is used as one of the excitation sources which contribute to the interior noise. Second, a full-trimmed FE carriage model is firstly constructed, and the simulated modal shapes and frequencies agree well with the measured ones, which has validated the global FE carriage model as well as the local FE models of the aluminum alloy-trim composite panel. Thus, the sound transmission loss model of any composite panel has indirectly been validated. Finally, the SAEF model of the carriage is constructed based on the accurate FE model and stimulated by the multi-physical-field excitations. The results show

Design and commission of an experimental test rig to apply a full-scale pressure load on composite sandwich panels representative of an aircraft secondary structure

International Nuclear Information System (INIS)

Crump, D A; Dulieu-Barton, J M; Savage, J

2010-01-01

This paper describes the design of a test rig, which is used to apply a representative pressure load to a full-scale composite sandwich secondary aircraft structure. A generic panel was designed with features to represent those in the composite sandwich secondary aircraft structure. To provide full-field strain data from the panels, the test rig was designed for use with optical measurement techniques such as thermoelastic stress analysis (TSA) and digital image correlation (DIC). TSA requires a cyclic load to be applied to a structure for the measurement of the strain state; therefore, the test rig has been designed to be mounted on a standard servo-hydraulic test machine. As both TSA and DIC require an uninterrupted view of the surface of the test panel, an important consideration in the design is facilitating the optical access for the two techniques. To aid the test rig design a finite element (FE) model was produced. The model provides information on the deflections that must be accommodated by the test rig, and ensures that the stress and strain levels developed in the panel when loaded in the test rig would be sufficient for measurement using TSA and DIC. Finally, initial tests using the test rig have shown it to be capable of achieving the required pressure and maintaining a cyclic load. It was also demonstrated that both TSA and DIC data can be collected from the panels under load, which are used to validate the stress and deflection derived from the FE model

1. Introduction. 2. Laboratory experiments. 3. Field experiments. 4. Integrated field-laboratory experiments. 5. Panel recommendations

International Nuclear Information System (INIS)

Anon.

1975-01-01

Some recommendations for the design of laboratory and field studies in marine radioecology are formulated. The difficulties concerning the comparability of various experimental methods used to measure the fluxes of radionuclides through marine organisms and ecosystems, and also the use of laboratory results to make predictions for the natural environment are discussed. Three working groups were established during the panel meeting, to consider laboratory experiments, field studies, and the design and execution of integrated laboratory and field studies respectively. A number of supporting papers dealing with marine radioecological experiments were presented

Dependence of the coefficient of environmental thermal losses of radiation-absorbing thermal exchange panels of flat solar collectors for heating heat-transfer fluid from their average operating and ambient temperatures

International Nuclear Information System (INIS)

Avezova, N.R.; Avezov, R.R.

2015-01-01

The approximation formula is derived for calculating the normalized coefficient of thermal losses of flat solar collectors (FSCs) for heating heat-transfer fluid (HTF). These are used in hot water supply systems in the warmer part of the year, depending on the average working surface temperature of their radiation-absorbing thermal exchange panels (RATEPs) (t"-_w_s_r) and the ambient temperature (t_a_m_b) in their realistic variation range. (author)

BUCLASP 3: A computer program for stresses and buckling of heated composite stiffened panels and other structures, user's manual

Science.gov (United States)

Tripp, L. L.; Tamekuni, M.; Viswanathan, A. V.

1973-01-01

The use of the computer program BUCLASP3 is described. The code is intended for thermal stress and instability analyses of structures such as unidirectionally stiffened panels. There are two types of instability analyses that can be effected by PAINT; (1) thermal buckling, and (2) buckling due to a specified inplane biaxial loading. Any structure that has a constant cross section in one direction, that may be idealized as an assemblage of beam elements and laminated flat and curved plate strip-elements can be analyzed. The two parallel ends of the panel must be simply supported, whereas arbitrary elastic boundary conditions may be imposed along any one or both external longitudinal side. Any variation in the temperature rise (from ambient) through the cross section of a panel is considered in the analyses but it must be assumed that in the longitudinal direction the temperature field is constant. Load distributions for the externally applied inplane biaxial loads are similar in nature to the permissible temperature field.

Polymeric flat focal field arrayed waveguide grating using electron-beam direct writing

Science.gov (United States)

Lu, Si; Yan, Yingbai; Jin, Guofan; Wong, W. H.; Pun, E. Y. B.

2004-06-01

A four-channel 400-GHz spacing flat focal field arrayed waveguide grating (AWG) demultiplexer is designed based on polymeric optical waveguide. The waveguide core-layer material is a newly developed negative tone epoxy Novolak resin (ENR) polymer with ultravoilet (UV) cured resin Norland optical adhesive 61 (NOA61) as the cladding layer. The device is fabricated using electron-beam direct writing, which has less processing steps than the reported polymeric AWGs. The experimental result is presented.

Panel discussion on near-field coupled processes with emphasis on performance assessment

International Nuclear Information System (INIS)

Codell, R.B.; Baca, R.G.; Ahola, M.P.

1996-01-01

The presentations in this panel discussion involve the general topic of near-field coupled processes and postclosure performance assessment with an emphasis on rock mechanics. The potential impact of near-field rock mass deformation on repository performance was discussed, as well as topics including long term excavation deterioration, the performance of geologic seals, and coupled processes concerning rock mechanics in performance assessments

IMac G4/800 (Flat Panel)

CERN Multimedia

2002-01-01

Apple introduced the iMac G4/800 on January 7, 2002. The total cost was about $2000 (base price of $1799 plus RAM upgrade). The iMac G4/800 has an 800 MHz G4 processor. The G4/800 has the following ports: three USB 1.1 ports, two Fire Wire 400-Mbps ports, one RJ-45, 10/100BASE-T Ethernet port, one RJ-11 56K V.90 modem port, one Mini-VGA output port, one speaker jack, and one headphone jack. There is a built in microphone set on the front of the monitor in the bottom left corner. There is a single internal SuperDrive capable of reading and writing CDs and DVDs. The disk drive is on the front of the computer. It opens by pushing the disk drive button on the iMac's keyboard. The monitor size is 15 inches. The G4/800 has a NVIDIA GeForce2 MX graphics processor with AGP 2X support that provides 32 MB of dedicated Double Data Rate (DDR) video memory. Native resolution is 1024 x 768, but the built in monitor is also capable of 640 x 480 and 800 x 600. RAM can be changed by removing a panel on the bottom of the chas...

The design and imaging characteristics of dynamic, solid-state, flat-panel x-ray image detectors for digital fluoroscopy and fluorography

International Nuclear Information System (INIS)

Cowen, A.R.; Davies, A.G.; Sivananthan, M.U.

2008-01-01

Dynamic, flat-panel, solid-state, x-ray image detectors for use in digital fluoroscopy and fluorography emerged at the turn of the millennium. This new generation of dynamic detectors utilize a thin layer of x-ray absorptive material superimposed upon an electronic active matrix array fabricated in a film of hydrogenated amorphous silicon (a-Si:H). Dynamic solid-state detectors come in two basic designs, the indirect-conversion (x-ray scintillator based) and the direct-conversion (x-ray photoconductor based). This review explains the underlying principles and enabling technologies associated with these detector designs, and evaluates their physical imaging characteristics, comparing their performance against the long established x-ray image intensifier television (TV) system. Solid-state detectors afford a number of physical imaging benefits compared with the latter. These include zero geometrical distortion and vignetting, immunity from blooming at exposure highlights and negligible contrast loss (due to internal scatter). They also exhibit a wider dynamic range and maintain higher spatial resolution when imaging over larger fields of view. The detective quantum efficiency of indirect-conversion, dynamic, solid-state detectors is superior to that of both x-ray image intensifier TV systems and direct-conversion detectors. Dynamic solid-state detectors are playing a burgeoning role in fluoroscopy-guided diagnosis and intervention, leading to the displacement of x-ray image intensifier TV-based systems. Future trends in dynamic, solid-state, digital fluoroscopy detectors are also briefly considered. These include the growth in associated three-dimensional (3D) visualization techniques and potential improvements in dynamic detector design

Surface runoff in flat terrain: How field topography and runoff generating processes control hydrological connectivity

NARCIS (Netherlands)

Appels, W.M.; Bogaart, P.W.; Bogaart, P.W.; Zee, van der S.E.A.T.M.

2016-01-01

In flat lowland agricultural catchments in temperate climate zones with highly permeable sandy soils, surface runoff is a rare process with a large impact on the redistribution of sediments and solutes and stream water quality. We examine hydrological data obtained on two field sites in the

Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors

Directory of Open Access Journals (Sweden)

Karim S. Karim

2011-05-01

Full Text Available In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs. We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE. Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the

Foil Panel Mirrors for Nonimaging Applications

Science.gov (United States)

Kuyper, D. J.; Castillo, A. A.

1984-01-01

Large durable, lightweight mirrors made by bonding thick aluminum foil to honeycomb panels or other rigid, flat backings. Mirrors suitable for use as infrared shields, telescope doors, solar-furnance doors, advertising displays, or other reflectors that require low thermal emissivity and high specularity but do not require precise surface figure necessary for imaging.

Effect of electromagnetic fields on the creation of scalar particles in a flat Robertson-Walker space-time

International Nuclear Information System (INIS)

Haouat, S.; Chekireb, R.

2012-01-01

The influence of electromagnetic fields on the creation of scalar particles from vacuum in a flat Robertson-Walker space-time is studied. The Klein-Gordon equation with varying electric field and constant magnetic one is solved. The Bogoliubov transformation method is applied to calculate the pair creation probability and the number density of created particles. It is shown that the electric field amplifies the creation of scalar particles while the magnetic field minimizes it. (orig.)

Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres

Science.gov (United States)

Suratwala, Tayyab; Steele, Rusty; Feit, Michael; Dylla-Spears, Rebecca; Desjardin, Richard; Mason, Dan; Wong, Lana; Geraghty, Paul; Miller, Phil; Shen, Nan

2014-01-01

Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial shape (i.e., surface figure), will converge to final surface figure with excellent surface quality under a fixed, unchanging set of polishing parameters in a single polishing iteration. In contrast, conventional full aperture polishing methods require multiple, often long, iterative cycles involving polishing, metrology and process changes to achieve the desired surface figure. The Convergent Polishing process is based on the concept of workpiece-lap height mismatch resulting in pressure differential that decreases with removal and results in the workpiece converging to the shape of the lap. The successful implementation of the Convergent Polishing process is a result of the combination of a number of technologies to remove all sources of non-uniform spatial material removal (except for workpiece-lap mismatch) for surface figure convergence and to reduce the number of rogue particles in the system for low scratch densities and low roughness. The Convergent Polishing process has been demonstrated for the fabrication of both flats and spheres of various shapes, sizes, and aspect ratios on various glass materials. The practical impact is that high quality optical components can be fabricated more rapidly, more repeatedly, with less metrology, and with less labor, resulting in lower unit costs. In this study, the Convergent Polishing protocol is specifically described for fabricating 26.5 cm square fused silica flats from a fine ground surface to a polished ~λ/2 surface figure after polishing 4 hr per surface on a 81 cm diameter polisher. PMID:25489745

Fire-induced reradiation underneath photovoltaic arrays on flat roofs

DEFF Research Database (Denmark)

Kristensen, Jens Steemann; Merci, Bart; Jomaas, Grunde

2018-01-01

The impact of the reflection of fire-induced heat from a gas burner was studied experimentally to gain knowledge on the interaction between photovoltaic (PV) panels and a fire on flat roofs. The heat flux was measured in a total of eight points at the same level as the top of the gas burner. The ...

Interacting new agegraphic tachyon, K-essence and dilaton scalar field models of dark energy in non-flat universe

Energy Technology Data Exchange (ETDEWEB)

Karami, K., E-mail: KKarami@uok.ac.i [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Khaledian, M.S.; Felegary, F.; Azarmi, Z. [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of)

2010-03-29

We study the correspondence between the tachyon, K-essence and dilaton scalar field models with the interacting new agegraphic dark energy model in the non-flat FRW universe. We reconstruct the potentials and the dynamics for these scalar field models, which describe accelerated expansion of the universe.

Interacting new agegraphic tachyon, K-essence and dilaton scalar field models of dark energy in non-flat universe

International Nuclear Information System (INIS)

Karami, K.; Khaledian, M.S.; Felegary, F.; Azarmi, Z.

2010-01-01

We study the correspondence between the tachyon, K-essence and dilaton scalar field models with the interacting new agegraphic dark energy model in the non-flat FRW universe. We reconstruct the potentials and the dynamics for these scalar field models, which describe accelerated expansion of the universe.

A full-field transmission x-ray microscope for time-resolved imaging of magnetic nanostructures

Energy Technology Data Exchange (ETDEWEB)

Ewald, J.; Nisius, T.; Abbati, G.; Baumbach, S.; Overbuschmann, J.; Wilhein, T. [Institute for X-Optics (IXO), Hochschule Koblenz, Joseph-Rovan-Allee 2, 53424 Remagen (Germany); Wessels, P.; Wieland, M.; Drescher, M. [The Hamburg Centre for Ultrafast Imaging (CUI), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Institut für Experimentalphysik, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Vogel, A. [Institut für Angewandte Physik, University of Hamburg, Jungiusstraße 11, 20355 Hamburg (Germany); Viefhaus, J. [Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg (Germany); Meier, G. [The Hamburg Centre for Ultrafast Imaging (CUI), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg (Germany)

2016-01-28

Sub-nanosecond magnetization dynamics of small permalloy (Ni{sub 80}Fe{sub 20}) elements has been investigated with a new full-field transmission microscope at the soft X-ray beamline P04 of the high brilliance synchrotron radiation source PETRA III. The soft X-ray microscope generates a flat-top illumination field of 20 μm diameter using a grating condenser. A tilted nanostructured magnetic sample can be excited by a picosecond electric current pulse via a coplanar waveguide. The transmitted light of the sample plane is directly imaged by a micro zone plate with < 65 nm resolution onto a 2D gateable X-ray detector to select one particular bunch in the storage ring that probes the time evolution of the dynamic information successively via XMCD spectromicroscopy in a pump-probe scheme. In the experiments it was possible to generate a homogeneously magnetized state in patterned magnetic layers by a strong magnetic Oersted field pulse of 200 ps duration and directly observe the recovery to the initial flux-closure vortex patterns.

TU-F-18C-02: Increasing Amorphous Selenium Thickness in Direct Conversion Flat-Panel Imagers for Contrast-Enhanced Dual-Energy Breast Imaging

International Nuclear Information System (INIS)

Scaduto, DA; Hu, Y-H; Zhao, W

2014-01-01

Purpose: Contrast-enhanced (CE) breast imaging using iodinated contrast agents requires imaging with x-ray spectra at energies greater than those used in mammography. Optimizing amorphous selenium (a-Se) flat panel imagers (FPI) for this higher energy range may increase lesion conspicuity. Methods: We compare imaging performance of a conventional FPI with 200 μm a-Se conversion layer to a prototype FPI with 300 μm a-Se layer. Both detectors are evaluated in a Siemens MAMMOMAT Inspiration prototype digital breast tomosynthesis (DBT) system using low-energy (W/Rh 28 kVp) and high-energy (W/Cu 49 kVp) x-ray spectra. Detectability of iodinated lesions in dual-energy images is evaluated using an iodine contrast phantom. Effects of beam obliquity are investigated in projection and reconstructed images using different reconstruction methods. The ideal observer signal-to-noise ratio is used as a figure-of-merit to predict the optimal a-Se thickness for CE lesion detectability without compromising conventional full-field digital mammography (FFDM) and DBT performance. Results: Increasing a-Se thickness from 200 μm to 300 μm preserves imaging performance at typical mammographic energies (e.g. W/Rh 28 kVp), and improves the detective quantum efficiency (DQE) for high energy (W/Cu 49 kVp) by 30%. While the more penetrating high-energy x-ray photons increase geometric blur due to beam obliquity in the FPI with thicker a-Se layer, the effect on lesion detectability in FBP reconstructions is negligible due to the reconstruction filters employed. Ideal observer SNR for CE objects shows improvements in in-plane detectability with increasing a-Se thicknesses, though small lesion detectability begins to degrade in oblique projections for a-Se thickness above 500 μm. Conclusion: Increasing a-Se thickness in direct conversion FPI from 200 μm to 300 μm improves lesion detectability in CE breast imaging with virtually no cost to conventional FFDM and DBT. This work was partially

Study of behaviour of workings in longwall panel based on field instrumentation

Energy Technology Data Exchange (ETDEWEB)

V.R. Sastry; Roshan Nair [National Institute of Technology Karnataka, Mangalore (India). Department of Mining Engineering

2009-07-01

The paper presents field monitoring study of two adjacent longwall panels based on stress measurements in longwall block and barrier, load transferred on to the gate roads and convergence measurements in the gate roads during face retreat in the panels. Results indicated that the section of barrier lying in the goaf experienced higher abutment stress when compared with the section lying ahead of face. There was a transfer of load in gate roads ahead of face after the occurrence of roof fall in goaf. Maximum cumulative convergence of more than 8 mm was observed in the gate roads during weightings.

Near-field modeling in Frenchman Flat, Nevada Test Site

International Nuclear Information System (INIS)

Pohlmann, K.; Shirley, C.; Andricevic, R.

1996-12-01

The US Department of Energy (DOE) is investigating the effects of nuclear testing in underground test areas (the UGTA program) at the Nevada Test Site. The principal focus of the UGTA program is to better understand and define subsurface radionuclide migration. The study described in this report focuses on the development of tools for generating maps of hydrogeologic characteristics of subsurface Tertiary volcanic units at the Frenchman Flat corrective Action Unit (CAU). The process includes three steps. The first step involves generation of three-dimensional maps of the geologic structure of subsurface volcanic units using geophysical logs to distinguish between two classes: densely welded tuff and nonwelded tuff. The second step generates three-dimensional maps of hydraulic conductivity utilizing the spatial distribution of the two geologic classes obtained in the first step. Each class is described by a correlation structure based on existing data on hydraulic conductivity, and conditioned on the generated spatial location of each class. The final step demonstrates the use of the maps of hydraulic conductivity for modeling groundwater flow and radionuclide transport in volcanic tuffs from an underground nuclear test at the Frenchman Flat CAU. The results indicate that the majority of groundwater flow through the volcanic section occurs through zones of densely welded tuff where connected fractures provide the transport pathway. Migration rates range between near zero to approximately four m/yr, with a mean rate of 0.68 m/yr. This report presents the results of work under the FY96 Near-Field Modeling task of the UGTA program

Final recommendations of the Peer Review Panel on the use of seismic methods for characterizing Yucca Mountain and vicinity

International Nuclear Information System (INIS)

1991-01-01

The Peer Review Panel was charged with deciding whether seismic methods, which had been utilized at Yucca Mountain with mixed results in the past, could provide useful information about the Tertiary structure in the Yucca Mountain area. The objectives of using seismic methods at Yucca Mountain are to: (a) obtain information about the structural character of the Paleozoic-Tertiary (Pz-T) contact, and (b) obtain information about the structural and volcanic details within the Tertiary and Quaternary section. The Panel recommends that a four part program be undertaken to test the utility of seismic reflection data for characterizing the structural setting of the Yucca Mountain area. The Panel feels strongly that all four parts of the program must be completed in order to provide the highest probability of success. The four parts of the program are: (a) drill or extend a deep hole in Crater Flat to provide depth control and allow for the identification of seismic reflectors in an area where good quality seismic reflection data are expected; (b) undertake a full seismic noise test in Crater Flat, test 2D receiver arrays as well as linear arrays; perform an expanding spread test using both P and S wave sources to obtain a quick look at the reflection quality in the area and see if shear wave reflections might provide structural information in areas of unsaturated rock; (c) acquire a P wave seismic reflection profile across Crater Flat through the deep control well, across Yucca Mountain, and continuing into Jackass Flats; and (d) acquire a standard VSP (vertical seismic profiling) in the deep control well to tie the seismic data into depth and to identify reflectors correctly

APPLIED ORIGAMI. Origami of thick panels.

Science.gov (United States)

Chen, Yan; Peng, Rui; You, Zhong

2015-07-24

Origami patterns, including the rigid origami patterns in which flat inflexible sheets are joined by creases, are primarily created for zero-thickness sheets. In order to apply them to fold structures such as roofs, solar panels, and space mirrors, for which thickness cannot be disregarded, various methods have been suggested. However, they generally involve adding materials to or offsetting panels away from the idealized sheet without altering the kinematic model used to simulate folding. We develop a comprehensive kinematic synthesis for rigid origami of thick panels that differs from the existing kinematic model but is capable of reproducing motions identical to that of zero-thickness origami. The approach, proven to be effective for typical origami, can be readily applied to fold real engineering structures. Copyright © 2015, American Association for the Advancement of Science.

Feasibility for the Use of Flat Booster Reflectors in Various Photovoltaic Installations

OpenAIRE

Gelegenis, John Joachim; Axaopoulos, Petros; Misailidis, Stavros; Giannakidis, George; Samarakou, Maria; Bonaros, Bassilios

2016-01-01

The feasibility for the addition of flat booster reflectors to PV panels is techno-economically investigated for various applications (building attached PVs, ground installations, grid-connected or stand-alone units) and various PV types (mono-crystalline and amorphous silicon PV panels). A model developed to this aim is applied to optimize the parameters of the PV/reflector module and to evaluate its applicability according to the solar radiation data of Athens (Greece). The reflectors may l...

Three-reflections telescope proposal as flat-field anastigmat for wide field observations at Dome C

Science.gov (United States)

Ferrari, M.; Lemaître, G.; Viotti, R.; La Padula, C.; Comte, G.; Blanc, M.; Boer, M.

It is now evident that the exceptional seeing at Dome C will allow, in the next years, to pursue astronomical programs with conditions better than at any other observatory in the world, and very close to space experiments. Considering a new type of wide-field telescope, particular astronomical programs could be well optimized for observations at Dome C such as surveys for the discovery and follow up of near-Earth asteroids, search for extra-solar planets using transit or micro-lensing events, and stellar luminosity variations. We propose to build a 1.5 2m class three-reflections telescope, with 1 1.5degree FOV, four times shorter than an equivalent Schmidt telescope, and providing a flat field without requiring a triplet- or quadruplet-lens corrector since its design is anastigmatic. We present the preliminary optical tests of such designs: MINITRUST1 and 2 are two 45cm identical prototypes based in France and Italy, and manufactured using active optics techniques.

Volume CT with a flat-panel detector on a mobile, isocentric C-arm: Pre-clinical investigation in guidance of minimally invasive surgery

International Nuclear Information System (INIS)

Siewerdsen, J.H.; Moseley, D.J.; Burch, S.; Bisland, S.K.; Bogaards, A.; Wilson, B.C.; Jaffray, D.A.

2005-01-01

A mobile isocentric C-arm (Siemens PowerMobil) has been modified in our laboratory to include a large area flat-panel detector (in place of the x-ray image intensifier), providing multi-mode fluoroscopy and cone-beam computed tomography (CT) imaging capability. This platform represents a promising technology for minimally invasive, image-guided surgical procedures where precision in the placement of interventional tools with respect to bony and soft-tissue structures is critical. The image quality and performance in surgical guidance was investigated in pre-clinical evaluation in image-guided spinal surgery. The control, acquisition, and reconstruction system are described. The reproducibility of geometric calibration, essential to achieving high three-dimensional (3D) image quality, is tested over extended time scales (7 months) and across a broad range in C-arm angulation (up to 45 deg.), quantifying the effect of improper calibration on spatial resolution, soft-tissue visibility, and image artifacts. Phantom studies were performed to investigate the precision of 3D localization (viz., fiber optic probes within a vertebral body) and effect of lateral projection truncation (limited field of view) on soft-tissue detectability in image reconstructions. Pre-clinical investigation was undertaken in a specific spinal procedure (photodynamic therapy of spinal metastases) in five animal subjects (pigs). In each procedure, placement of fiber optic catheters in two vertebrae (L1 and L2) was guided by fluoroscopy and cone-beam CT. Experience across five procedures is reported, focusing on 3D image quality, the effects of respiratory motion, limited field of view, reconstruction filter, and imaging dose. Overall, the intraoperative cone-beam CT images were sufficient for guidance of needles and catheters with respect to bony anatomy and improved surgical performance and confidence through 3D visualization and verification of transpedicular trajectories and tool placement

Cross Talk Study to the Single Photon Response of a Flat Panel PMT for the RICH Upgrade at LHCb

CERN Multimedia

Arnaboldi, C; Calvi, M; Fanchini, E; Gotti, C; Maino, M; Matteuzzi, C; Perego, D L; Pessina, G; Wang, J C

2009-01-01

The Ring Imaging CHerenkov, RICH, detector at LHCb is now readout by Hybrid Photon Detectors. In view of its upgrade a possible option is the adoption of the flat panel Photon Multipliers Tubes, PMT. An important issue for the good determination of the rings produced in the sensitive media is a negligible level of cross talk. We have experimentally studied the cross talk from the 64x64 pixels of the H9500 PMT from Hamamatsu. Results have shown that at the single photon signal level, as expected at LHCb, the statistics applied to the small number of electrons generated at the first dynode of the PMT chain leads to a cross talk mechanism that must be interpreted in term of the percentage of the number of induced signals rather than on the amplitude of the induced signals. The threshold to suppress cross talk must be increased to a significant fraction of the single photon signal for the worst case. The number of electrons generated at the first dynode is proportional to the biasing voltage. Measurements have sh...

Particle creation by a black hole as a consequence of quantum-field effects in flat space-time

International Nuclear Information System (INIS)

Nugayev, R.M.

1985-01-01

The application of quantum-field flat-space-time results to a black hole reveals the domain and the mechanism of particle creation. The Hawking radiation is ''squeezed out'' by the tail of gravitational-field potential barrier in the [1.5 Rg, infinity] region. Its black-body spectrum is due to the interaction of virtual particles with the ''cavity'' formed by the potential barrier

Development of high quantum efficiency, flat panel, thick detectors for megavoltage x-ray imaging: An experimental study of a single-pixel prototype

International Nuclear Information System (INIS)

Mei, X.; Pang, G.

2005-01-01

Our overall goal is to develop a new generation of electronic portal imaging devices (EPIDs) with a quantum efficiency (QE) more than an order of magnitude higher and a spatial resolution equivalent to that of EPIDs currently used for portal imaging. A novel design of such a high QE flat-panel based EPID was introduced recently and its feasibility was investigated theoretically [see Pang and Rowlands, Med. Phys. 31, 3004 (2004)]. In this work, we constructed a prototype single-pixel detector based on the novel design. Some fundamental imaging properties including the QE, spatial resolution, and sensitivity of the prototype detector were measured with a 6 MV beam. It has been shown that the experimental results agree well with theoretical predictions and further development based on the novel design including the construction of a prototype area detector is warranted

High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium

DEFF Research Database (Denmark)

Safafar, Hamed; Hass, Michael Z.; Møller, Per

2016-01-01

salina biomass, with a focus on eicosapentaenoic acid (EPA). Variations in fatty acid composition, lipids, protein, amino acids, tocopherols and pigments were studied and results compared to algae cultivated on F/2 media as reference. Mixed growth media and process water enhanced the nutritional quality...... of Nannochloropsis salina in laboratory scale when compared to algae cultivated in standard F/2 medium. Data from laboratory scale translated to the large scaleusing a 4000 L flat panel photo-bioreactor system. The algae growth rate in winter conditions in Denmark was slow, but results revealed that large...... after 21 days of cultivation. Variations in chemical compositions of Nannochloropsis salina were studied during the course of cultivation. Nannochloropsis salina can be presented as a good candidate for winter time cultivation in Denmark.The resulting biomass is a rich source of EPA and also a good...

Flat-Panel Detector—Based Volume Computed Tomography: A Novel 3D Imaging Technique to Monitor Osteolytic Bone Lesions in a Mouse Tumor Metastasis Model

Directory of Open Access Journals (Sweden)

Jeannine Missbach-Guentner

2007-09-01

Full Text Available Skeletal metastasis is an important cause of mortality in patients with breast cancer. Hence, animal models, in combination with various imaging techniques, are in high demand for preclinical assessment of novel therapies. We evaluated the applicability of flat-panel volume computed tomography (fpVCT to noninvasive detection of osteolytic bone metastases that develop in severe immunodeficient mice after intracardial injection of MDA-MB-231 breast cancer cells. A single fpVCT scan at 200-wm isotropic resolution was employed to detect osteolysis within the entire skeleton. Osteolytic lesions identified by fpVCT correlated with Faxitron X-ray analysis and were subsequently confirmed by histopathological examination. Isotropic three-dimensional image data sets obtained by fpVCT were the basis for the precise visualization of the extent of the lesion within the cortical bone and for the measurement of bone loss. Furthermore, fpVCT imaging allows continuous monitoring of growth kinetics for each metastatic site and visualization of lesions in more complex regions of the skeleton, such as the skull. Our findings suggest that fpVCT is a powerful tool that can be used to monitor the occurrence and progression of osteolytic lesions in vivo and can be further developed to monitor responses to antimetastatic therapies over the course of the disease.

Rain concentration and sheltering effect of solar panels on cultivated plots

Science.gov (United States)

Elamri, Yassin; Cheviron, Bruno; Mange, Annabelle; Dejean, Cyril; Liron, François; Belaud, Gilles

2018-02-01

Agrivoltaism is the association of agricultural and photovoltaic energy production on the same land area, coping with the increasing pressure on land use and water resources while delivering clean and renewable energy. However, the solar panels located above the cultivated plots also have a seemingly yes unexplored effect on rain redistribution, sheltering large parts of the plot but redirecting concentrated fluxes on a few locations. The spatial heterogeneity in water amounts observed on the ground is high in the general case; its dynamical patterns are directly attributable to the mobile panels through their geometrical characteristics (dimensions, height, coverage percentage) and the strategies selected to rotate them around their support tube. A coefficient of variation is used to measure this spatial heterogeneity and to compare it with the coefficient of uniformity that classically describes the efficiency of irrigation systems. A rain redistribution model (AVrain) was derived from literature elements and theoretical grounds and then validated from experiments in both field and controlled conditions. AVrain simulates the effective rain amounts on the plot from a few forcing data (rainfall, wind velocity and direction) and thus allows real-time strategies that consist in operating the panels so as to limit the rain interception mainly responsible for the spatial heterogeneities. Such avoidance strategies resulted in a sharp decrease in the coefficient of variation, e.g. 0.22 vs. 2.13 for panels held flat during one of the monitored rain events, which is a fairly good uniformity score for irrigation specialists. Finally, the water amounts predicted by AVrain were used as inputs to Hydrus-2D for a brief exploratory study on the impact of the presence of solar panels on rain redistribution at shallow depths within soils: similar, more diffuse patterns were simulated and were coherent with field measurements.

High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium

Directory of Open Access Journals (Sweden)

Hamed Safafar

2016-07-01

Full Text Available Nannochloropsis salina was grown on a mixture of standard growth media and pre-gasified industrial process water representing effluent from a local biogas plant. The study aimed to investigate the effects of enriched growth media and cultivation time on nutritional composition of Nannochloropsis salina biomass, with a focus on eicosapentaenoic acid (EPA. Variations in fatty acid composition, lipids, protein, amino acids, tocopherols and pigments were studied and results compared to algae cultivated on F/2 media as reference. Mixed growth media and process water enhanced the nutritional quality of Nannochloropsis salina in laboratory scale when compared to algae cultivated in standard F/2 medium. Data from laboratory scale translated to the large scale using a 4000 L flat panel photo-bioreactor system. The algae growth rate in winter conditions in Denmark was slow, but results revealed that large-scale cultivation of Nannochloropsis salina at these conditions could improve the nutritional properties such as EPA, tocopherol, protein and carotenoids compared to laboratory-scale cultivated microalgae. EPA reached 44.2% ± 2.30% of total fatty acids, and α-tocopherol reached 431 ± 28 µg/g of biomass dry weight after 21 days of cultivation. Variations in chemical compositions of Nannochloropsis salina were studied during the course of cultivation. Nannochloropsis salina can be presented as a good candidate for winter time cultivation in Denmark. The resulting biomass is a rich source of EPA and also a good source of protein (amino acids, tocopherols and carotenoids for potential use in aquaculture feed industry.

Combined-load buckling behavior of metal-matrix composite sandwich panels under different thermal environments

Science.gov (United States)

Ko, William L.; Jackson, Raymond H.

1991-01-01

Combined compressive and shear buckling analysis was conducted on flat rectangular sandwich panels with the consideration of transverse shear effects of the core. The sandwich panel is fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. The results show that the square panel has the highest combined load buckling strength, and that the buckling strength decreases sharply with the increases of both temperature and panel aspect ratio. The effect of layup (fiber orientation) on the buckling strength of the panels was studied in detail. The metal matrix composite sandwich panel was much more efficient than the sandwich panel with nonreinforced face sheets and had the same specific weight.

Photovoltaic systems on flat roofs. A new approach; Photovoltaique sur toits plats. Une nouvelle approche. Rapport final

Energy Technology Data Exchange (ETDEWEB)

Roecker, C.; Bonvin, J.; Muller, A.

1999-06-01

Flat roofs are among the best choices to mount photovoltaics on buildings. Nevertheless, standard solutions in use till the mid-nineties were quite poor, as far as price, aesthetics and ease of maintenance were concerned. This report presents, following a comprehensive typology study of flat roofs, a series of new and innovative solutions, fully developed and tested. There are three main system groups, differing essentially by the ballasting method used to keep the panels on the roof: (i) the SOFREL family, using concrete blocs weighting; (ii) the SOLBAC family, using existing ballast weighting; and (iii) the SOLGREEN family, using ballast and earth weighting. Some more systems, not finalised, are also described, giving some hints for possible new developments. To conclude, this project has brought three main systems, all three already or soon commercially available, allowing a simple and easy mounting of photovoltaic panels on any flat roof type. (author)

Performance Evaluation of PV Panel Under Dusty Condition

Directory of Open Access Journals (Sweden)

Abhishek Kumar Tripathi

2017-11-01

Full Text Available The performance of PV panel depends on the incoming sunlight on its surface. The accumulated airborne dust particles on panel surface creates a barrier in the path of sunlight and panel surface, which significantly reduces the amount of solar radiation falling on the panel surface. The present study shows a significant reduction in short circuit current and power output of PV panel due to dust deposition on its surface, whereas the reduction in open circuit voltage is not much prominent. This study has been carried in the field as well as in the laboratory. The reduction in maximum power output of PV panel for both the studies ensures a linear relation with the dust deposition on its surface. In the field study, the reduction in the power output due to 12.86gm of dust deposition on the panel surface was 43.18%, whereas in the laboratory study it was 44.75% due to 11gm of dust deposition Article History: Received July 10th 2017; Received in revised form Sept 15th 2017x; Accepted 1st Oct 2017; Available online How to Cite This Article: Tripathi, A.K., Aruna, M. and Murthy, Ch.,S.N. (2017. Performance Evaluation of PV Panel Under Dusty Condition. International Journal of Renewable Energy Develeopment, 6(3, 225-233. https://doi.org/10.14710/ijred.6.3.225-233

A two-parameter family of exact asymptotically flat solutions to the Einstein-scalar field equations

International Nuclear Information System (INIS)

Nikonov, V V; Tchemarina, Ju V; Tsirulev, A N

2008-01-01

We consider a static spherically symmetric real scalar field, minimally coupled to Einstein gravity. A two-parameter family of exact asymptotically flat solutions is obtained by using the inverse problem method. This family includes non-singular solutions, black holes and naked singularities. For each of these solutions the respective potential is partially negative but positive near spatial infinity. (comments, replies and notes)

Concrete Flow in Diaphragm Wall Panels : A Full-Scale In-Situ Test

NARCIS (Netherlands)

Van Dalen, J.H.; Bosch, J.W.; Broere, W.

2015-01-01

Flow processes, taking place during the concreting of diaphragm wall panels (D-wall panels), are of great importance for the quality of the wall. During this phase, the bentonite, present in the excavated trench, should be completely replaced by concrete in a controlled way. In literature several

Flat Surface Damage Detection System (FSDDS)

Science.gov (United States)

Williams, Martha; Lewis, Mark; Gibson, Tracy; Lane, John; Medelius, Pedro; Snyder, Sarah; Ciarlariello, Dan; Parks, Steve; Carrejo, Danny; Rojdev, Kristina

2013-01-01

The Flat Surface Damage Detection system (FSDDS} is a sensory system that is capable of detecting impact damages to surfaces utilizing a novel sensor system. This system will provide the ability to monitor the integrity of an inflatable habitat during in situ system health monitoring. The system consists of three main custom designed subsystems: the multi-layer sensing panel, the embedded monitoring system, and the graphical user interface (GUI). The GUI LABVIEW software uses a custom developed damage detection algorithm to determine the damage location based on the sequence of broken sensing lines. It estimates the damage size, the maximum depth, and plots the damage location on a graph. Successfully demonstrated as a stand alone technology during 2011 D-RATS. Software modification also allowed for communication with HDU avionics crew display which was demonstrated remotely (KSC to JSC} during 2012 integration testing. Integrated FSDDS system and stand alone multi-panel systems were demonstrated remotely and at JSC, Mission Operations Test using Space Network Research Federation (SNRF} network in 2012. FY13, FSDDS multi-panel integration with JSC and SNRF network Technology can allow for integration with other complementary damage detection systems.

An investigation of flat panel equipment variables on image quality with a dedicated cardiac phantom

Energy Technology Data Exchange (ETDEWEB)

Dragusin, O; Bosmans, H [Department of Radiology, University Hospital Gasthuisberg, 49, Herestraat, 3000-Leuven (Belgium); Pappas, C; Desmet, W [Department of Cardiology, University Hospital Gasthuisberg, 49, Herestraat, 3000-Leuven (Belgium)], E-mail: odragusin@yahoo.com

2008-09-21

Image quality (IQ) evaluation plays a key role in the process of optimization of new x-ray systems. Ideally, this process should be supported by real clinical images, but ethical issues and differences in anatomy and pathology of patients make it impossible. Phantom studies might overcome these issues. This paper presents the IQ evaluation of 30 cineangiographic films acquired with a cardiac flat panel system. The phantom used simulates the anatomy of the heart and allows the circulation of contrast agent boluses through coronary arteries. Variables investigated with influence on IQ and radiation dose are: tube potential, detector dose, added Copper filters, dynamic density optimization (DDO) and viewing angle. The IQ evaluation consisted of scoring 4 simulated calcified lesions located on different coronary artery segments in terms of degree of visualization. Eight cardiologists rated the lesions using a five-point scale ((1) lesion not visible to (5) very good visibility). Radiation doses associated to the angiograms are expressed in terms of incident air kerma (IAK) and effective dose that has been calculated with PCXMX software (STUK, Finland) from the exposure settings assuming a standard sized patient of 70 Kg. Mean IQ scores ranged from 1.68 to 4.88. The highest IQ scores were obtained for the angiograms acquired with tube potential 80 kVp, no added Cu filters, DDO 60%, RAO and LAO views and the highest entrance detector dose that has been used in the present study, namely 0.17 {mu}Gy/im. Radiation doses (IAK {approx}40 mGy and effective dose of 1 mSv) were estimated for angiograms acquired at 15 frames s{sup -1}, detector field-of-view 20 cm, and a length of 5 s. The following parameters improved the IQ factor significantly: a change in tube potential from 96 to 80 kVp, detector dose from 0.10 {mu}Gy/im to 0.17 {mu}Gy/im, the absence of Copper filtration. DDO variable which is a post-processing parameter should be carefully evaluated because it alters the

An investigation of flat panel equipment variables on image quality with a dedicated cardiac phantom

International Nuclear Information System (INIS)

Dragusin, O; Bosmans, H; Pappas, C; Desmet, W

2008-01-01

Image quality (IQ) evaluation plays a key role in the process of optimization of new x-ray systems. Ideally, this process should be supported by real clinical images, but ethical issues and differences in anatomy and pathology of patients make it impossible. Phantom studies might overcome these issues. This paper presents the IQ evaluation of 30 cineangiographic films acquired with a cardiac flat panel system. The phantom used simulates the anatomy of the heart and allows the circulation of contrast agent boluses through coronary arteries. Variables investigated with influence on IQ and radiation dose are: tube potential, detector dose, added Copper filters, dynamic density optimization (DDO) and viewing angle. The IQ evaluation consisted of scoring 4 simulated calcified lesions located on different coronary artery segments in terms of degree of visualization. Eight cardiologists rated the lesions using a five-point scale ((1) lesion not visible to (5) very good visibility). Radiation doses associated to the angiograms are expressed in terms of incident air kerma (IAK) and effective dose that has been calculated with PCXMX software (STUK, Finland) from the exposure settings assuming a standard sized patient of 70 Kg. Mean IQ scores ranged from 1.68 to 4.88. The highest IQ scores were obtained for the angiograms acquired with tube potential 80 kVp, no added Cu filters, DDO 60%, RAO and LAO views and the highest entrance detector dose that has been used in the present study, namely 0.17 μGy/im. Radiation doses (IAK ∼40 mGy and effective dose of 1 mSv) were estimated for angiograms acquired at 15 frames s -1 , detector field-of-view 20 cm, and a length of 5 s. The following parameters improved the IQ factor significantly: a change in tube potential from 96 to 80 kVp, detector dose from 0.10 μGy/im to 0.17 μGy/im, the absence of Copper filtration. DDO variable which is a post-processing parameter should be carefully evaluated because it alters the quality of the

TRANSVERSE MODES FOR FLAT INTER-BUNCH WAKES*

CERN Document Server

Burov, A

2013-01-01

If inter-bunch wake fields are flat, i.e. their variations over a bunch length can be neglected, all coherent modes have the same coupled-bunch structure, provided the bunches can be treated as identical by their inner qualities (train theorem). If a flat feedback is strong enough, the transverse modes are single-bunch, provided the inter-bunch wakes are also flat (damper theorem).

A study on the effect of flat plate friction resistance on speed performance prediction of full scale

Directory of Open Access Journals (Sweden)

Park Dong-Woo

2015-01-01

Full Text Available Flat plate friction lines hare been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study- was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996, and the curve developed by Katsui et al (2005. In the second part, change in the form factor by three kinds of

Line operators in theories of class S, quantized moduli space of flat connections, and Toda field theory

International Nuclear Information System (INIS)

Coman, Ioana; Teschner, Joerg

2015-05-01

Non-perturbative aspects of N=2 supersymmetric gauge theories of class S are deeply encoded in the algebra of functions on the moduli space M flat of at SL(N)-connections on Riemann surfaces. Expectation values of Wilson and 't Hooft line operators are related to holonomies of flat connections, and expectation values of line operators in the low-energy effective theory are related to Fock-Goncharov coordinates on M flat . Via the decomposition of UV line operators into IR line operators, we determine their noncommutative algebra from the quantization of Fock-Goncharov Laurent polynomials, and find that it coincides with the skein algebra studied in the context of Chern-Simons theory. Another realization of the skein algebra is generated by Verlinde network operators in Toda field theory. Comparing the spectra of these two realizations provides non-trivial support for their equivalence. Our results can be viewed as evidence for the generalization of the AGT correspondence to higher-rank class S theories.

Properties of flat-pressed wood plastic composites containing fire retardants

Science.gov (United States)

Nadir Ayrilmis; Jan. T. Benthien; Heiko Thoemen; Robert H. White

2011-01-01

This study investigated physical, mechanical, and fire properties of the flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) [5 or 15% by weight (wt)] at 50 wt % of the wood flour (WF). The WPC panels were made from dry-blended WF, polypropylene (PP) with maleic anhydride grafted PP (2 wt %), and FR powder formulations using a...

MO-AB-BRA-07: Low Dose Imaging with Avalanche Amorphous Selenium Flat Panel Imager

Energy Technology Data Exchange (ETDEWEB)

Scheuermann, J; Howansky, A; Goldan, A; Tanioka, K; Zhao, W [Stony Brook University, Stony Brook, New York (United States); Leveille, S; Tousignant, O [2Analogic Canada, Saint-laurent, Quebec (Canada)

2016-06-15

Purpose: We present the first active matrix flat panel imager (AMFPI) capable of producing x-ray quantum noise limited images at low doses by overcoming the electronic noise through signal amplification by photoconductive avalanche gain (gav). The indirect detector fabricated uses an optical sensing layer of amorphous selenium (a-Se) known as High-Gain Avalanche Rushing Photoconductor (HARP). The detector design is called Scintillator HARP (SHARP)-AMFPI. This is the first image sensor to utilize solid-state HARP technology. Methods: The detector’s electronic readout is a 24 × 30 cm{sup 2} array of thin film transistors (TFT) with a pixel pitch of 85 µm. The HARP structure consists of a 15 µm layer of a-Se isolated from the high voltage (HV) and signal electrode by a 2 µm thick hole blocking layer and electron blocking layer, respectively, to reduce dark current. A 150 µm thick structured CsI scintillator with reflective backing and a fiber optic faceplate (FOP) was coupled to the semi-transparent HV bias electrode of the HARP structure. Images were acquired using a 30 kVp Mo/Mo spectrum typically used in mammography. Results: Optical sensitivity measurements demonstrate that gav = 76 ± 5 can be achieved over the entire active area of the detector. At a constant dose to the detector of 6.67 µGy, image quality increases with gav until the effective electronic noise is negligible. Quantum noise limited images can be obtained with doses as low as 0.18 µGy. Conclusion: We demonstrate the feasibility of utilizing avalanche gain to overcome electronic noise. The indirect detector fabricated is the first solid-state imaging sensor to use HARP, and the largest active area HARP sensor to date. Our future work is to improve charge transport within the HARP structure and utilize a transparent HV electrode.

Whole field strain measurement in critical thin adhesive layer of single- and double-sided repaired CFRP panel using DIC

Science.gov (United States)

Kashfuddoja, Mohammad; Ramji, M.

2015-03-01

In the present work, the behavior of thin adhesively layer in patch repaired carbon fiber reinforced polymer (CFRP) panel under tensile load is investigated experimentally using digital image correlation (DIC) technique. The panel is made of Carbon/epoxy composite laminate and the stacking sequence in the panel is [0º]4. A circular hole of 10 mm diameter (d) is drilled at the center of the panel to mimic the case of low velocity impact damage removal. The panel with open hole is repaired with double sided (symmetrical) and single sided (unsymmetrical) rectangular patch made of same panel material having stacking sequence of [0º]3. Araldite 2011 is used for bonding the patch onto the panel over the damaged area. The global behavior of thin adhesive layer is examined by analyzing whole field strain distribution using DIC. Longitudinal, peel and shear strain field in both double and single sided repair configuration is studied and a compression is made between them. An estimate of shear transfer length which is an essential parameter in arriving at an appropriate overlap length in patch design is proposed from DIC and FEA. Damage development, failure mechanism and load displacement behavior is also investigated. The experimental results are compared with the numerical predictions.

Radiation monitor training program at Rocky Flats

International Nuclear Information System (INIS)

Medina, L.C.; Kittinger, W.D.; Vogel, R.M.

The Rocky Flats Radiation Monitor Training Program is tailored to train new health physics personnel in the field of radiation monitoring. The purpose of the prescribed materials and media is to be consistent in training in all areas of Rocky Flats radiation monitoring job involvement

Fire Resistant Panels for the Tunnel Linings

Directory of Open Access Journals (Sweden)

Gravit Marina

2016-01-01

Full Text Available Presents the results of studies of innovative materials in the field of experimental and theoretical research fire resistance fireproof panels Pyro-Safe Aestuver T. Owing to the assembly simplicity, materials cheapness, high ecological standard, recycling, reuse potential, are benefit. Research work is running to improve the knowledge about fireproof panels Pyro-Safe Aestuver T for tunnel lining, its basic performance, its long term behavior and in particular also its fire proof for example when used for the lining of road tunnels.

Flat directions in flipped SU(5). I: All-order analysis

Energy Technology Data Exchange (ETDEWEB)

Cleaver, G.B. E-mail: gcleaver@rainbow.physics.tamu.edu; Ellis, J. E-mail: john.ellis@cern.ch; Nanopoulos, D.V. E-mail: dimitri@soda.physics.tamu.edu

2001-04-23

We present a systematic classification of field directions for the string-derived flipped SU(5) model that are D- and F-flat to all orders. Properties of the flipped SU(5) model with field values in these directions are compared to those associated with other flat directions that have been shown to be F-flat to specific finite orders in the superpotential. We discuss the phenomenological Higgs spectrum, and quark and charged-lepton mass textures.

Flat Directions in Flipped SU(5); 1, All-Order Analysis

CERN Document Server

Cleaver, G B; Nanopoulos, Dimitri V

2001-01-01

We present a systematic classification of field directions for the string-derived flipped SU(5) model that are D- and F-flat to all orders. Properties of the flipped SU(5) model with field values in these directions are compared to those associated with other flat directions that have been shown to be F-flat to specific finite orders in the superpotential. We discuss the phenomenological Higgs spectrum, and quark and charged-lepton mass textures.

Flat Optical Fiber Daylighting System with Lateral Displacement Sun-Tracking Mechanism for Indoor Lighting

Directory of Open Access Journals (Sweden)

Ngoc Hai Vu

2017-10-01

Full Text Available An essential impact which can improve the indoor environment and save on power consumption for artificial lighting is utilization of daylight. Optical fiber daylighting technology offers a way to use direct daylight for remote spaces in a building. However, the existing paradigm based on the precise orientation of sunlight concentrator toward the Sun is very costly and difficult to install on the roof of buildings. Here, we explore an alternative approach using mirror-coated lens array and planar waveguide to develop a flat optical fiber daylighting system (optical fiber daylighting panel with lateral displacement Sun-tracking mechanism. Sunlight collected and reflected by each mirror-coated lens in a rectangular lens array is coupled into a planar waveguide using cone prisms placed at each lens focus. This geometry yields a thin, flat profile for Sunlight concentrator. Our proposed concentrating panel can be achieved with 35 mm thickness while the concentrator’s width and length are 500 mm × 500 mm. The commercial optical simulation tool (LightToolsTM was used to develop the simulation models and analyze the system performance. Simulation results based on the designed system demonstrated an optical efficiency of 51.4% at a concentration ratio of 125. The system can support utilizing a lateral displacement Sun-tracking system, which allows for replacing bulky and robust conventional rotational Sun-tracking systems. This study shows a feasibility of a compact and inexpensive optical fiber daylighting system to be installed on the roof of buildings.

Comparison between radiation exposure levels using an image intensifier and a flat-panel detector-based system in image-guided central venous catheter placement in children weighing less than 10 kg

Energy Technology Data Exchange (ETDEWEB)

Miraglia, Roberto; Maruzzelli, Luigi; Cortis, Kelvin; Gerasia, Roberta; Maggio, Simona; Luca, Angelo [Diagnostic and Therapeutic Services, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo (Italy); Piazza, Marcello [Department of Anesthesia, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo (Italy); Tuzzolino, Fabio [Department of Information Technology, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo (Italy)

2014-09-10

Ultrasound-guided central venous puncture and fluoroscopic guidance during central venous catheter (CVC) positioning optimizes technical success and lowers the complication rates in children, and is therefore considered standard practice. The purpose of this study was to compare the radiation exposure levels recorded during CVC placement in children weighing less than 10 kg in procedures performed using an image intensifier-based angiographic system (IIDS) to those performed in a flat-panel detector-based interventional suite (FPDS). A retrospective review of 96 image-guided CVC placements, between January 2008 and October 2013, in 49 children weighing less than 10 kg was performed. Mean age was 8.2 ± 4.4 months (range: 1-22 months). Mean weight was 7.1 ± 2.7 kg (range: 2.5-9.8 kg). The procedures were classified into two categories: non-tunneled and tunneled CVC placement. Thirty-five procedures were performed with the IIDS (21 non-tunneled CVC, 14 tunneled CVC); 61 procedures were performed with the FPDS (47 non-tunneled CVC, 14 tunneled CVC). For non-tunneled CVC, mean DAP was 113.5 ± 126.7 cGy cm{sup 2} with the IIDS and 15.9 ± 44.6 cGy . cm{sup 2} with the FPDS (P < 0.001). For tunneled CVC, mean DAP was 84.6 ± 81.2 cGy . cm{sup 2} with the IIDS and 37.1 ± 33.5 cGy cm{sup 2} with the FPDS (P = 0.02). The use of flat-panel angiographic equipment reduces radiation exposure in small children undergoing image-guided CVC placement. (orig.)

Panel 5: Microbiology and Immunology Panel

Science.gov (United States)

Murphy, Timothy F.; Chonmaitree, Tasnee; Barenkamp, Stephen; Kyd, Jennelle; Nokso-Koivisto, Johanna; Patel, Janak A.; Heikkinen, Terho; Yamanaka, Noboru; Ogra, Pearay; Swords, W. Edward; Sih, Tania; Pettigrew, Melinda M.

2014-01-01

Objective The objective is to perform a comprehensive review of the literature from January 2007 through June 2011 on the virology, bacteriology, and immunology related to otitis media. Data Sources PubMed database of the National Library of Medicine. Review Methods Three subpanels with co-chairs comprising experts in the virology, bacteriology, and immunology of otitis media were formed. Each of the panels reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a second draft was created. The entire panel met at the 10th International Symposium on Recent Advances in Otitis Media in June 2011 and discussed the review and refined the content further. A final draft was created, circulated, and approved by the panel. Conclusion Excellent progress has been made in the past 4 years in advancing an understanding of the microbiology and immunology of otitis media. Advances include laboratory-based basic studies, cell-based assays, work in animal models, and clinical studies. Implications for Practice The advances of the past 4 years formed the basis of a series of short-term and long-term research goals in an effort to guide the field. Accomplishing these goals will provide opportunities for the development of novel interventions, including new ways to better treat and prevent otitis media. PMID:23536533

Heat transfer in flow past a continuously moving semi-infinite flat plate in transverse magnetic field with heat flux

Digital Repository Service at National Institute of Oceanography (India)

Murty, T.V.R.

Thermal boundary layer on a continuously moving semi-infinite flat plate in the presence of transverse magnetic field with heat flux has been examined. Similarity solutions have been derived and the resulting equations are integrated numerically...

Comparison of higher irradiance and black panel temperature UV backsheet exposures to field performance

Science.gov (United States)

Felder, Thomas C.; Gambogi, William J.; Phillips, Nancy; MacMaster, Steven W.; Yu, Bao-Ling; Trout, T. John

2017-08-01

The need for faster PV qualification tests that more accurately match field observations is leading to tests with higher acceleration levels, and validating the new tests through comparison to field data is an important step. We have tested and compared a wide panel of backsheets according to a proposed new backsheet UV exposure qualification standard from the International Electrotechnical Commission (IEC). Weathering Technical Standard IEC 62788-7-2 specifies higher irradiance and higher black panel temperature UV Xenon exposures. We tested PVF, PVDF, PET, PA and FEVEbased backsheets in glass laminates and simple backsheet coupons in UV exposure condition A3 (0.8W/sqmnm@340nm and 90° C BPT) We find mild yellowing with no mechanical loss in the original lower intensity ASTM G155 0.55 W/sqm-nm 70C BPT exposure condition. The new A3 exposures creates mechanical loss in sensitive backsheets, with no effect on known durable backsheets. Results from the new exposure are closer to field mechanical loss data.

Study of noise reduction characteristics of double-wall panels

Science.gov (United States)

Navaneethan, R.; Quayle, B.; Stevenson, S.; Graham, M.

1983-05-01

The noise reduction characteristics of general aviation type, flat, double-wall structures were investigated. The experimental study was carried out on 20-by-20 inch panels with an exposed area of 18 by 18 inches. A frequency range from 20 to 5000 Hz was covered. The experimental results, in general, follow the expected trends. At low frequencies the double-wall structures are no better than the single-wall structures. However, for depths normally used in the general aviation industry, the double-wall panels are very attractive. The graphite-spoxy skin panels have higher noise reduction at very low frequencies ( 100 Hz) than the Kevlar skin panels. But the aluminum panels have higher noise reduction in the high frequency region, due to their greater mass. Use of fiberglass insulation is not effective in the low frequency region, and at times it is even negative. But the insulation is effective in the high-frequency region. The theoretical model for predicting the transmission loss of these multilayered panels is also discussed.

Comparison of scatter rejection and low-contrast performance of scan equalization digital radiography (SEDR), slot-scan digital radiography, and full-field digital radiography systems for chest phantom imaging

International Nuclear Information System (INIS)

Liu Xinming; Shaw, Chris C.; Lai, Chao-Jen; Wang Tianpeng

2011-01-01

Purpose: To investigate and compare the scatter rejection properties and low-contrast performance of the scan equalization digital radiography (SEDR) technique to the slot-scan and conventional full-field digital radiography techniques for chest imaging. Methods: A prototype SEDR system was designed and constructed with an a-Se flat-panel (FP) detector to improve image quality in heavily attenuating regions of an anthropomorphic chest phantom. Slot-scanning geometry was used to reject scattered radiation without attenuating primary x rays. The readout scheme of the FP was modified to erase accumulated scatter signals prior to image readout. A 24-segment beam width modulator was developed to regulate x-ray exposures regionally and compensate for the low x-ray flux in heavily attenuating regions. To measure the scatter-to-primary ratios (SPRs), a 2 mm thick lead plate with a 2-D array of aperture holes was used to measure the primary signals, which were then subtracted from those obtained without the lead plate to determine scatter components. A 2-D array of aluminum beads (3 mm in diameter) was used as the low-contrast objects to measure the contrast ratios (CRs) and contrast-to-noise ratios (CNRs) for evaluating the low-contrast performance in chest phantom images. A set of two images acquired with the same techniques were subtracted from each other to measure the noise levels. SPRs, CRs, and CNRs of the SEDR images were measured in four anatomical regions of chest phantom images and compared to those of slot-scan images and full-field images acquired with and without antiscatter grid. Results: The percentage reduction of SPR (percentage of SPRs reduced with scatter removal/rejection methods relative to that for nongrid full-field imaging) averaged over four anatomical regions was measured to be 80%, 83%, and 71% for SEDR, slot-scan, and full-field with grid, respectively. The average CR over four regions was found to improve over that for nongrid full-field

Comparison of scatter rejection and low-contrast performance of scan equalization digital radiography (SEDR), slot-scan digital radiography, and full-field digital radiography systems for chest phantom imaging

Energy Technology Data Exchange (ETDEWEB)

Liu Xinming; Shaw, Chris C.; Lai, Chao-Jen; Wang Tianpeng [Department of Imaging Physics, Digital Imaging Research Laboratory, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009 (United States)

2011-01-15

Purpose: To investigate and compare the scatter rejection properties and low-contrast performance of the scan equalization digital radiography (SEDR) technique to the slot-scan and conventional full-field digital radiography techniques for chest imaging. Methods: A prototype SEDR system was designed and constructed with an a-Se flat-panel (FP) detector to improve image quality in heavily attenuating regions of an anthropomorphic chest phantom. Slot-scanning geometry was used to reject scattered radiation without attenuating primary x rays. The readout scheme of the FP was modified to erase accumulated scatter signals prior to image readout. A 24-segment beam width modulator was developed to regulate x-ray exposures regionally and compensate for the low x-ray flux in heavily attenuating regions. To measure the scatter-to-primary ratios (SPRs), a 2 mm thick lead plate with a 2-D array of aperture holes was used to measure the primary signals, which were then subtracted from those obtained without the lead plate to determine scatter components. A 2-D array of aluminum beads (3 mm in diameter) was used as the low-contrast objects to measure the contrast ratios (CRs) and contrast-to-noise ratios (CNRs) for evaluating the low-contrast performance in chest phantom images. A set of two images acquired with the same techniques were subtracted from each other to measure the noise levels. SPRs, CRs, and CNRs of the SEDR images were measured in four anatomical regions of chest phantom images and compared to those of slot-scan images and full-field images acquired with and without antiscatter grid. Results: The percentage reduction of SPR (percentage of SPRs reduced with scatter removal/rejection methods relative to that for nongrid full-field imaging) averaged over four anatomical regions was measured to be 80%, 83%, and 71% for SEDR, slot-scan, and full-field with grid, respectively. The average CR over four regions was found to improve over that for nongrid full-field

Integrated radiotherapy imaging system (IRIS): design considerations of tumour tracking with linac gantry-mounted diagnostic x-ray systems with flat-panel detectors.

Science.gov (United States)

Berbeco, Ross I; Jiang, Steve B; Sharp, Gregory C; Chen, George T; Mostafavi, Hassan; Shirato, Hiroki

2004-01-21

The design of an integrated radiotherapy imaging system (IRIS), consisting of gantry mounted diagnostic (kV) x-ray tubes and fast read-out flat-panel amorphous-silicon detectors, has been studied. The system is meant to be capable of three main functions: radiographs for three-dimensional (3D) patient set-up, cone-beam CT and real-time tumour/marker tracking. The goal of the current study is to determine whether one source/panel pair is sufficient for real-time tumour/marker tracking and, if two are needed, the optimal position of each relative to other components and the isocentre. A single gantry-mounted source/imager pair is certainly capable of the first two of the three functions listed above and may also be useful for the third, if combined with prior knowledge of the target's trajectory. This would be necessary because only motion in two dimensions is visible with a single imager/source system. However, with previously collected information about the trajectory, the third coordinate may be derived from the other two with sufficient accuracy to facilitate tracking. This deduction of the third coordinate can only be made if the 3D tumour/marker trajectory is consistent from fraction to fraction. The feasibility of tumour tracking with one source/imager pair has been theoretically examined here using measured lung marker trajectory data for seven patients from multiple treatment fractions. The patients' selection criteria include minimum mean amplitudes of the tumour motions greater than 1 cm peak-to-peak. The marker trajectory for each patient was modelled using the first fraction data. Then for the rest of the data, marker positions were derived from the imager projections at various gantry angles and compared with the measured tumour positions. Our results show that, due to the three dimensionality and irregular trajectory characteristics of tumour motion, on a fraction-to-fraction basis, a 'monoscopic' system (single source/imager) is inadequate for

Panel acoustic contribution analysis.

Science.gov (United States)

Wu, Sean F; Natarajan, Logesh Kumar

2013-02-01

Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated.

"Flat-Fish" vacuum chamber for the ISR

CERN Multimedia

CERN PhotoLab

1983-01-01

The "Flat-Fish" vacuum chamber was a very special one for the ISR beam intersection I-4, inside the Split-Field Magnet. Technical descriptions are given with pictures 7802042 and 7712182. There were several generations of this chamber. This picture was taken during the last year of ISR operation. See also 7510230X, 7511123X, 7802039, 7802041. A flat-fish type vacuum chamber was also used at I-8, inside the Open Axial Field Magnet (OAFM, experiment 807 on large transverse momentum collision products), see 7901358.

Optimization of dual-energy subtraction chest radiography by use of a direct-conversion flat-panel detector system.

Science.gov (United States)

Fukao, Mari; Kawamoto, Kiyosumi; Matsuzawa, Hiroaki; Honda, Osamu; Iwaki, Takeshi; Doi, Tsukasa

2015-01-01

We aimed to optimize the exposure conditions in the acquisition of soft-tissue images using dual-energy subtraction chest radiography with a direct-conversion flat-panel detector system. Two separate chest images were acquired at high- and low-energy exposures with standard or thick chest phantoms. The high-energy exposure was fixed at 120 kVp with the use of an auto-exposure control technique. For the low-energy exposure, the tube voltages and entrance surface doses ranged 40-80 kVp and 20-100 % of the dose required for high-energy exposure, respectively. Further, a repetitive processing algorithm was used for reduction of the image noise generated by the subtraction process. Seven radiology technicians ranked soft-tissue images, and these results were analyzed using the normalized-rank method. Images acquired at 60 kVp were of acceptable quality regardless of the entrance surface dose and phantom size. Using a repetitive processing algorithm, the minimum acceptable doses were reduced from 75 to 40 % for the standard phantom and to 50 % for the thick phantom. We determined that the optimum low-energy exposure was 60 kVp at 50 % of the dose required for the high-energy exposure. This allowed the simultaneous acquisition of standard radiographs and soft-tissue images at 1.5 times the dose required for a standard radiograph, which is significantly lower than the values reported previously.

Non-destructive, preclinical evaluation of root canal anatomy of human teeth with flat-panel detector volume CT (FD-VCT)

International Nuclear Information System (INIS)

Heidrich, G.; Hassepass, F.; Dullin, C.; Grabbe, E.; Attin, T.; Hannig, C.

2005-01-01

Purpose: Successful endodontic diagnostics and therapy call for adequate depiction of the root canal anatomy with multimodal diagnostic imaging. The aim of the present study is to evaluate visualization of the endodont with flat-panel detector volume CT (FD-VCT). Materials and methods: 13 human teeth were examined with the prototype of a FD-VCT. After data acquisition and generation of volume data sets in volume rendering technology (VRT), the findings obtained were compared to conventional X-rays and cross-section preparations of the teeth. Results: The anatomical structures of the endodont such as root canals, side canals and communications between different root canals as well as dentricles could be detected precisely with FD-VCT. The length of curved root canals was also determined accurately. The spatial resolution of the system is around 140 μm. Only around 73% of the main root canals detected with FD-VCT and 87% of the roots could be visualized with conventional dental X-rays. None of the side canals, shown with FD-VCT, was detectable on conventional X-rays. In all cases the enamel and dentin of the teeth could be well delineated. No differences in image quality could be discerned between stored and freshly extracted teeth, or between primary and adult teeth. (orig.)

Embedded nonvolatile memory devices with various silicon nitride energy band gaps on glass used for flat panel display applications

International Nuclear Information System (INIS)

Son, Dang Ngoc; Van Duy, Nguyen; Jung, Sungwook; Yi, Junsin

2010-01-01

Nonvolatile memory (NVM) devices with a nitride–nitride–oxynitride stack structure on a rough poly-silicon (poly-Si) surface were fabricated using a low-temperature poly-Si (LTPS) thin film transistor technology on glass substrates for application of flat panel display (FPD). The plasma-assisted oxidation/nitridation method is used to form a uniform oxynitride with an ultrathin tunneling layer on a rough LTPS surface. The NVMs, using a Si-rich silicon nitride film as a charge-trapping layer, were proposed as one of the solutions for the improvement of device performance such as the program/erase speed, the memory window and the charge retention characteristics. To further improve the vertical scaling and charge retention characteristics of NVM devices, the high-κ high-density N-rich SiN x films are used as a blocking layer. The fabricated NVM devices have outstanding electrical properties, such as a low threshold voltage, a high ON/OFF current ratio, a low subthreshold swing, a low operating voltage of less than ±9 V and a large memory window of 3.7 V, which remained about 1.9 V over a period of 10 years. These characteristics are suitable for electrical switching and data storage with in FPD application

Non-Abelian bosonization as a nonholonomic transformation from a flat to a curved field space

International Nuclear Information System (INIS)

Kleinert, H.

1997-01-01

There exists a simple rule by which path integrals for the motion of a point particle in a flat space can be transformed correctly into those in a curved space. This rule arose from well-established methods in the theory of plastic deformations, where crystals with defects are described mathematically by applying active nonholonomic coordinate transformations to ideal crystals. In the context of time-sliced path integrals, this has given rise to a quantum equivalence principle which determines the short-time action and functional integration measure of fluctuating orbits in spaces with curvature and torsion. The nonholonomic transformations have a nontrivial Jacobian which in curved spaces produces an additional energy proportional to the curvature scalar, thereby canceling an equal term found earlier by DeWitt in his formulation of Feynman close-quote s time-sliced path integral in curved space. The importance of this cancelation has been documented in various systems (H-atom, particle on the surface of a sphere, spinning top). Here we point out its relevance to the bosonization of a non-Abelian one-dimensional quantum field theory, whose fields live in a flat field space. The bosonized version is a quantum-mechanical path integral of a point particle moving in a space with constant curvature. The additional term introduced by the Jacobian is crucial for the identity between original and bosonized theory. A useful bosonization tool is the so-called Hubbard endash Stratonovich formula for which we find a nonabelian version. copyright 1997 Academic Press, Inc

Method of estimating patient skin dose from dose displayed on medical X-ray equipment with flat panel detector

International Nuclear Information System (INIS)

Fukuda, Atsushi; Koshida, Kichiro; Togashi, Atsuhiko; Matsubara, Kousuke

2004-01-01

The International Electrotechnical Commission (IEC) has stipulated that medical X-ray equipment for interventional procedures must display radiation doses such as air kerma in free air at the interventional reference point and dose area product to establish radiation safety for patients (IEC 60601-2-43). However, it is necessary to estimate entrance skin dose for the patient from air kerma for an accurate risk assessment of radiation skin injury. To estimate entrance skin dose from displayed air kerma in free air at the interventional reference point, it is necessary to consider effective energy, the ratio of the mass-energy absorption coefficient for skin and air, and the backscatter factor. In addition, since automatic exposure control is installed in medical X-ray equipment with flat panel detectors, it is necessary to know the characteristics of control to estimate exposure dose. In order to calculate entrance skin dose under various conditions, we investigated clinical parameters such as tube voltage, tube current, pulse width, additional filter, and focal spot size, as functions of patient body size. We also measured the effective energy of X-ray exposure for the patient as a function of clinical parameter settings. We found that the conversion factor from air kerma in free air to entrance skin dose is about 1.4 for protection. (author)

Flat rotation curves using scalar-tensor theories

Energy Technology Data Exchange (ETDEWEB)

Cervantes-Cota, Jorge L [Depto de Fisica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 D.F. (Mexico); RodrIguez-Meza, M A [Depto de Fisica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 D.F. (Mexico); Nunez, Dario [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 D.F. (Mexico)

2007-11-15

We computed flat rotation curves from scalar-tensor theories in their weak field limit. Our model, by construction, fits a flat rotation profile for velocities of stars. As a result, the form of the scalar field potential and DM distribution in a galaxy are determined. By taking into account the constraints for the fundamental parameters of the theory ({lambda}, {alpha}), it is possible to obtain analytical results for the density profiles. For positive and negative values of {alpha}, the DM matter profile is as cuspy as NFW's.

Brushless Cleaning of Solar Panels and Windows

Science.gov (United States)

Schneider, H. W.

1982-01-01

Machine proposed for cleaning solar panels and reflectors uses multiple vortexes of air, solvent, and water to remove dust and dirt. Uses no brushes that might abrade solar surfaces and thereby reduce efficiency. Machine can be readily automated and can be used on curved surfaces such as aparbolic reflectors as well as on flat ones. Cleaning fluids are recycled, so that large quantities of water and solvent are not needed.

A performance comparison of flat-panel imager-based MV and kV cone-beam CT

International Nuclear Information System (INIS)

Groh, B.A.; Siewerdsen, J.H.; Drake, D.G.; Wong, J.W.; Jaffray, D.A.

2002-01-01

The use of cone-beam computed tomography (CBCT) has been proposed for guiding the delivery of radiation therapy, and investigators have examined the use of both kilovoltage (kV) and megavoltage (MV) x-ray beams in the development of such CBCT systems. In this paper, the inherent contrast and signal-to-noise ratio (SNR) performance for a variety of existing and hypothetical detectors for CBCT are investigated analytically as a function of imaging dose and object size. Theoretical predictions are compared to the results of experimental investigations employing large-area flat-panel imagers (FPIs) at kV and MV energies. Measurements were performed on two different FPI-based CBCT systems: a bench-top prototype incorporating an FPI and kV x-ray source (100 kVp x rays), and a system incorporating an FPI mounted on the gantry of a medical linear accelerator (6 MV x rays). The SNR in volume reconstructions was measured as a function of dose and found to agree reasonably with theoretical predictions. These results confirm the theoretically predicted advantages of employing kV energy x rays in imaging soft-tissue structures found in the human body. While MV CBCT may provide a valuable means of correcting 3D setup errors and may offer an advantage in terms of simplicity of mechanical integration with a linear accelerator (e.g., implementation in place of a portal imager), kV CBCT offers significant performance advantages in terms of image contrast and SNR per unit dose for visualization of soft-tissue structures. The relatively poor SNR performance at MV energies is primarily a result of the low x-ray quantum efficiencies (∼a few percent or less) that are currently achieved with FPIs at high energies. Furthermore, kV CBCT with an FPI offers the potential of combined volumetric and radiographic/fluoroscopic imaging using the same device

Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

International Nuclear Information System (INIS)

Siewerdsen, Jeffrey H.

2011-01-01

The development of large-area flat-panel X-ray detectors (FPDs) has spurred investigation in a spectrum of advanced medical imaging applications, including tomosynthesis and cone-beam CT (CBCT). Recent research has extended image quality metrics and theoretical models to such applications, providing a quantitative foundation for the assessment of imaging performance as well as a general framework for the design, optimization, and translation of such technologies to new applications. For example, cascaded systems models of the Fourier domain metrics, such as noise-equivalent quanta (NEQ), have been extended to these modalities to describe the propagation of signal and noise through the image acquisition and reconstruction chain and to quantify the factors that govern spatial resolution, image noise, and detectability. Moreover, such models have demonstrated basic agreement with human observer performance for a broad range of imaging conditions and imaging tasks. These developments in image science have formed a foundation for the knowledgeable development and translation of CBCT to new applications in image-guided interventions-for example, CBCT implemented on a mobile surgical C-arm for intraoperative 3D imaging. The ability to acquire high-quality 3D images on demand during surgical intervention overcomes conventional limitations of surgical guidance in the context of preoperative images alone. A prototype mobile C-arm developed in academic-industry partnership demonstrates CBCT with low radiation dose, sub-mm spatial resolution, and soft-tissue visibility potentially approaching that of diagnostic CT. Integration of the 3D imaging system with real-time tracking, deformable registration, endoscopic video, and 3D visualization offers a promising addition to the surgical arsenal in interventions ranging from head-and-neck/skull base surgery to spine, orthopaedic, thoracic, and abdominal surgeries. Cadaver studies show the potential for significant boosts in surgical

Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

Energy Technology Data Exchange (ETDEWEB)

Siewerdsen, Jeffrey H., E-mail: jeff.siewerdsen@jhu.edu [Department of Biomedical Engineering, Johns Hopkins University, Traylor Building, Room 718, 720 Rutland Avenue, Baltimore, MD 21205 (United States)

2011-08-21

The development of large-area flat-panel X-ray detectors (FPDs) has spurred investigation in a spectrum of advanced medical imaging applications, including tomosynthesis and cone-beam CT (CBCT). Recent research has extended image quality metrics and theoretical models to such applications, providing a quantitative foundation for the assessment of imaging performance as well as a general framework for the design, optimization, and translation of such technologies to new applications. For example, cascaded systems models of the Fourier domain metrics, such as noise-equivalent quanta (NEQ), have been extended to these modalities to describe the propagation of signal and noise through the image acquisition and reconstruction chain and to quantify the factors that govern spatial resolution, image noise, and detectability. Moreover, such models have demonstrated basic agreement with human observer performance for a broad range of imaging conditions and imaging tasks. These developments in image science have formed a foundation for the knowledgeable development and translation of CBCT to new applications in image-guided interventions-for example, CBCT implemented on a mobile surgical C-arm for intraoperative 3D imaging. The ability to acquire high-quality 3D images on demand during surgical intervention overcomes conventional limitations of surgical guidance in the context of preoperative images alone. A prototype mobile C-arm developed in academic-industry partnership demonstrates CBCT with low radiation dose, sub-mm spatial resolution, and soft-tissue visibility potentially approaching that of diagnostic CT. Integration of the 3D imaging system with real-time tracking, deformable registration, endoscopic video, and 3D visualization offers a promising addition to the surgical arsenal in interventions ranging from head-and-neck/skull base surgery to spine, orthopaedic, thoracic, and abdominal surgeries. Cadaver studies show the potential for significant boosts in surgical

Dirac fields in flat FLRW cosmology: Uniqueness of the Fock quantization

Energy Technology Data Exchange (ETDEWEB)

Cortez, Jerónimo, E-mail: jacq@ciencias.unam.mx [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Elizaga Navascués, Beatriz, E-mail: beatriz.elizaga@iem.cfmac.csic.es [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Martín-Benito, Mercedes, E-mail: m.martin@hef.ru.nl [Radboud University Nijmegen, Institute for Mathematics, Astrophysics and Particle Physics, Heyendaalseweg 135, NL-6525 AJ Nijmegen (Netherlands); Mena Marugán, Guillermo A., E-mail: mena@iem.cfmac.csic.es [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Velhinho, José M., E-mail: jvelhi@ubi.pt [Universidade da Beira Interior, Rua Marquês d’Ávila e Bolama, 6201-001, Covilhã (Portugal)

2017-01-15

We address the issue of the infinite ambiguity that affects the construction of a Fock quantization of a Dirac field propagating in a cosmological spacetime with flat compact sections. In particular, we discuss a physical criterion that restricts to a unique possibility (up to unitary equivalence) the infinite set of available vacua. We prove that this desired uniqueness is guaranteed, for any possible choice of spin structure on the spatial sections, if we impose two conditions. The first one is that the symmetries of the classical system must be implemented quantum mechanically, so that the vacuum is invariant under the symmetry transformations. The second and more important condition is that the constructed theory must have a quantum dynamics that is implementable as a (non-trivial) unitary operator in Fock space. Actually, this unitarity of the quantum dynamics leads us to identify as explicitly time dependent some very specific contributions of the Dirac field. In doing that, we essentially characterize the part of the dynamics governed by the Dirac equation that is unitarily implementable. The uniqueness of the Fock vacuum is attained then once a physically motivated convention for the concepts of particles and antiparticles is fixed.

Dirac fields in flat FLRW cosmology: Uniqueness of the Fock quantization

International Nuclear Information System (INIS)

Cortez, Jerónimo; Elizaga Navascués, Beatriz; Martín-Benito, Mercedes; Mena Marugán, Guillermo A.; Velhinho, José M.

2017-01-01

We address the issue of the infinite ambiguity that affects the construction of a Fock quantization of a Dirac field propagating in a cosmological spacetime with flat compact sections. In particular, we discuss a physical criterion that restricts to a unique possibility (up to unitary equivalence) the infinite set of available vacua. We prove that this desired uniqueness is guaranteed, for any possible choice of spin structure on the spatial sections, if we impose two conditions. The first one is that the symmetries of the classical system must be implemented quantum mechanically, so that the vacuum is invariant under the symmetry transformations. The second and more important condition is that the constructed theory must have a quantum dynamics that is implementable as a (non-trivial) unitary operator in Fock space. Actually, this unitarity of the quantum dynamics leads us to identify as explicitly time dependent some very specific contributions of the Dirac field. In doing that, we essentially characterize the part of the dynamics governed by the Dirac equation that is unitarily implementable. The uniqueness of the Fock vacuum is attained then once a physically motivated convention for the concepts of particles and antiparticles is fixed.

3D flat holography: entropy and logarithmic corrections

International Nuclear Information System (INIS)

Bagchi, Arjun; Basu, Rudranil

2014-01-01

We compute the leading corrections to the Bekenstein-Hawking entropy of the Flat Space Cosmological (FSC) solutions in 3D flat spacetimes, which are the flat analogues of the BTZ black holes in AdS 3 . The analysis is done by a computation of density of states in the dual 2D Galilean Conformal Field Theory and the answer obtained by this matches with the limiting value of the expected result for the BTZ inner horizon entropy as well as what is expected for a generic thermodynamic system. Along the way, we also develop other aspects of holography of 3D flat spacetimes

Reconstructing interacting entropy-corrected holographic scalar field models of dark energy in the non-flat universe

Energy Technology Data Exchange (ETDEWEB)

Karami, K; Khaledian, M S [Department of Physics, University of Kurdistan, Pasdaran Street, Sanandaj (Iran, Islamic Republic of); Jamil, Mubasher, E-mail: KKarami@uok.ac.ir, E-mail: MS.Khaledian@uok.ac.ir, E-mail: mjamil@camp.nust.edu.pk [Center for Advanced Mathematics and Physics (CAMP), National University of Sciences and Technology (NUST), Islamabad (Pakistan)

2011-02-15

Here we consider the entropy-corrected version of the holographic dark energy (DE) model in the non-flat universe. We obtain the equation of state parameter in the presence of interaction between DE and dark matter. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the interacting entropy-corrected holographic DE model.

Strain Behavior of Concrete Panels Subjected to Different Nose Shapes of Projectile Impact

Directory of Open Access Journals (Sweden)

Sangkyu Lee

2018-03-01

Full Text Available This study evaluates the fracture properties and rear-face strain distribution of nonreinforced and hooked steel fiber-reinforced concrete panels penetrated by projectiles of three different nose shapes: sharp, hemispherical, and flat. The sharp projectile nose resulted in a deeper penetration because of the concentration of the impact force. Conversely, the flat projectile nose resulted in shallower penetrations. The penetration based on different projectile nose shapes is directly related to the impact force transmitted to the rear face. Scabbing can be more accurately predicted by the tensile strain on the rear face of concrete due to the projectile nose shape. The tensile strain on the rear face of the concrete was reduced by the hooked steel fiber reinforcement because the hooked steel fiber absorbed some of the impact stress transmitted to the rear face of the concrete. Consequently, the strain behavior on the rear face of concrete according to the projectile nose shape was confirmed.

Developing a solar panel testing system

Directory of Open Access Journals (Sweden)

Árpád Rácz

2009-10-01

Full Text Available Solar energy is increasingly used togenerate electricity for individual households. There isa wide variety of solar panel technologies, whichshould be tested at an individual level during theirlifetime. In this paper, the development of a testingstation at the University of Debrecen is presented. Thetesting system can be used for research andeducational purposes and for in field applicationsequally well.

Innovative Ballasted Flat Roof Solar PV Racking System

Energy Technology Data Exchange (ETDEWEB)

Peek, Richard T. [Cascade Engineering, Grand Rapids, MI (United States)

2014-12-15

The objective of this project was to reduce the cost of racking for PV solar on flat commercial rooftops. Cost reductions would come from both labor savings and material savings related to the installation process. The rack would need to accommodate the majority of modules available on the market. Cascade Engineering has a long history of converting traditional metal type applications over to plastic. Injection molding of plastics have numerous advantages including selection of resin for the application, placing the material exactly where it is needed, designing in features that will speed up the installation process, and weight reduction of the array. A plastic rack would need to meet the requirements of UL2703, Mounting systems, mounting devices, clamping/retention devices, and ground lugs for use with flat-plate photovoltaic modules and panels. Comparing original data to the end of project racking design, racking material costs were reduced 50% and labor costs reduced 64%. The racking product accommodates all 60 and 72 cell panels on the market, meets UL2703 requirements, contributes only 1.3 pounds per square foot of weight to the array, requires little ballast to secure the array, automatically grounds the module when the module is secured, stacks/nests well for shipping/fewer lifts to the roof, provides integrated wire routing, allows water to drain on the roof, and accommodates various seismic roof connections. Project goals were achieved as noted in the original funding application.

A new signal restoration method based on deconvolution of the Point Spread Function (PSF) for the Flat-Field Holographic Concave Grating UV spectrometer system

Science.gov (United States)

Dai, Honglin; Luo, Yongdao

2013-12-01

In recent years, with the development of the Flat-Field Holographic Concave Grating, they are adopted by all kinds of UV spectrometers. By means of single optical surface, the Flat-Field Holographic Concave Grating can implement dispersion and imaging that make the UV spectrometer system design quite compact. However, the calibration of the Flat-Field Holographic Concave Grating is very difficult. Various factors make its imaging quality difficult to be guaranteed. So we have to process the spectrum signal with signal restoration before using it. Guiding by the theory of signals and systems, and after a series of experiments, we found that our UV spectrometer system is a Linear Space- Variant System. It means that we have to measure PSF of every pixel of the system which contains thousands of pixels. Obviously, that's a large amount of calculation .For dealing with this problem, we proposes a novel signal restoration method. This method divides the system into several Linear Space-Invariant subsystems and then makes signal restoration with PSFs. Our experiments turn out that this method is effective and inexpensive.

Flat directions in left-right symmetric string derived models

International Nuclear Information System (INIS)

Cleaver, Gerald B.; Clements, David J.; Faraggi, Alon E.

2002-01-01

The only string models known to reproduce the minimal supersymmetric standard model in the low energy effective field theory are those constructed in the free fermionic formulation. We demonstrate the existence of quasirealistic free fermionic heterotic string models in which supersymmetric singlet flat directions do not exist. This raises the possibility that supersymmetry is broken perturbatively in such models by the one-loop Fayet-Iliopoulos term. We show, however, that supersymmetric flat directions that utilize vacuum expectation values of some non-Abelian fields in the massless string spectrum do exist in the model. We argue that hidden sector condensates lift the flat directions and break supersymmetry hierarchically

Fracture Analysis of the FAA/NASA Wide Stiffened Panels

Science.gov (United States)

Seshadri, B. R.; Newman, J. C., Jr.; Dawicke, D. S.; Young, R. D.

1999-01-01

This paper presents the fracture analyses conducted on the FAA/NASA stiffened and unstiffened panels using the STAGS (STructural Analysis of General Shells) code with the critical crack-tip-opening angle (CTOA) fracture criterion. The STAGS code with the "plane-strain" core option was used in all analyses. Previous analyses of wide, flat panels have shown that the high-constraint conditions around a crack front, like plane strain, has to be modeled in order for the critical CTOA fracture criterion to predict wide panel failures from small laboratory tests. In the present study, the critical CTOA value was determined from a wide (unstiffened) panel with anti-buckling guides. The plane-strain core size was estimated from previous fracture analyses and was equal to about the sheet thickness. Rivet flexibility and stiffener failure was based on methods and criteria, like that currently used in industry. STAGS and the CTOA criterion were used to predict load-against-crack extension for the wide panels with a single crack and multiple-site damage cracking at many adjacent rivet holes. Analyses were able to predict stable crack growth and residual strength within a few percent (5%) of stiffened panel tests results but over predicted the buckling failure load on an unstiffened panel with a single crack by 10%.

Application of panel methods in external store load calculations

CSIR Research Space (South Africa)

Van Den Broek, GJ

1984-07-01

Full Text Available below the wing is first considered; then, the effect of the wing panelling in the leading edge region, where the singularity distributions show large gradients, on the flow field is studied. Both lift and thickness effects are taken into account....

A Patch Density Recommendation based on Convergence Studies for Vehicle Panel Vibration Response resulting from Excitation by a Diffuse Acoustic Field

Science.gov (United States)

Smith, Andrew; LaVerde, Bruce; Jones, Douglas; Towner, Robert; Waldon, James; Hunt, Ron

2013-01-01

Producing fluid structural interaction estimates of panel vibration from an applied pressure field excitation are quite dependent on the spatial correlation of the pressure field. There is a danger of either over estimating a low frequency response or under predicting broad band panel response in the more modally dense bands if the pressure field spatial correlation is not accounted for adequately. It is a useful practice to simulate the spatial correlation of the applied pressure field over a 2d surface using a matrix of small patch area regions on a finite element model (FEM). Use of a fitted function for the spatial correlation between patch centers can result in an error if the choice of patch density is not fine enough to represent the more continuous spatial correlation function throughout the intended frequency range of interest. Several patch density assumptions to approximate the fitted spatial correlation function are first evaluated using both qualitative and quantitative illustrations. The actual response of a typical vehicle panel system FEM is then examined in a convergence study where the patch density assumptions are varied over the same model. The convergence study results illustrate the impacts possible from a poor choice of patch density on the analytical response estimate. The fitted correlation function used in this study represents a diffuse acoustic field (DAF) excitation of the panel to produce vibration response.

Simulated hail impact testing of photovoltaic solar panels

Science.gov (United States)

Moore, D.; Wilson, A.; Ross, R.

1978-01-01

Techniques used to simulate and study the effect of hail on photovoltaic solar panels are described. Simulated hail stones (frozen ice spheres projected at terminal velocity) or steel balls were applied by air guns, gravity drop, or static loading. Tests with simulated hail and steel balls yielded different results. The impact strength of 10 commercially available flat-plate photovoltaic modules was tested. It was found that none of the six panel designs incorporating clear potting silicone material as the outermost layer remained undamaged by 1-in. simulated hailstones, while a photovoltaic module equipped with a 0.188-in.-thick acrylic cover sheet would be able to withstand the impact of a 2-in.-diameter hailstone.

Piecewise flat gravitational waves

NARCIS (Netherlands)

van de Meent, M.

2011-01-01

We examine the continuum limit of the piecewise flat locally finite gravity model introduced by ’t Hooft. In the linear weak field limit, we find the energy–momentum tensor and metric perturbation of an arbitrary configuration of defects. The energy–momentum turns out to be restricted to satisfy

C-arm flat-panel CT arthrography of the shoulder: Radiation dose considerations and preliminary data on diagnostic performance

International Nuclear Information System (INIS)

Guggenberger, Roman; Ulbrich, Erika J.; Kaelin, Pascal; Pfammatter, Thomas; Alkadhi, Hatem; Andreisek, Gustav; Dietrich, Tobias J.; Scholz, Rosemarie; Koehler, Christoph; Elsaesser, Thilo; Le Corroller, Thomas

2017-01-01

To investigate radiation dose and diagnostic performance of C-arm flat-panel CT (FPCT) versus standard multi-detector CT (MDCT) shoulder arthrography using MRI-arthrography as reference standard. Radiation dose of two different FPCT acquisitions (5 and 20 s) and standard MDCT of the shoulder were assessed using phantoms and thermoluminescence dosimetry. FPCT arthrographies were performed in 34 patients (mean age 44 ± 15 years). Different joint structures were quantitatively and qualitatively assessed by two independent radiologists. Inter-reader agreement and diagnostic performance were calculated. Effective radiation dose was markedly lower in FPCT 5 s (0.6 mSv) compared to MDCT (1.7 mSv) and FPCT 20 s (3.4 mSv). Contrast-to-noise ratios (CNRs) were significantly (p < 0.05) higher in FPCT 20-s versus 5-s protocols. Inter-reader agreements of qualitative ratings ranged between κ = 0.47-1.0. Sensitivities for cartilage and rotator cuff pathologies were low for FPCT 5-s (40 % and 20 %) and moderate for FPCT 20-s protocols (75 % and 73 %). FPCT showed high sensitivity (81-86 % and 89-99 %) for bone and acromioclavicular-joint pathologies. Using a 5-s protocol FPCT shoulder arthrography provides lower radiation dose compared to MDCT but poor sensitivity for cartilage and rotator cuff pathologies. FPCT 20-s protocol is moderately sensitive for cartilage and rotator cuff tendon pathology with markedly higher radiation dose compared to MDCT. (orig.)

C-arm flat-panel CT arthrography of the shoulder: Radiation dose considerations and preliminary data on diagnostic performance

Energy Technology Data Exchange (ETDEWEB)

Guggenberger, Roman; Ulbrich, Erika J.; Kaelin, Pascal; Pfammatter, Thomas; Alkadhi, Hatem; Andreisek, Gustav [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zuerich (Switzerland); Dietrich, Tobias J. [Balgrist University Hospital, Department of Radiology, Zurich (Switzerland); Scholz, Rosemarie; Koehler, Christoph; Elsaesser, Thilo [Siemens Healthcare GmbH, Business Area Advanced Therapies, Forchheim (Germany); Le Corroller, Thomas [Aix-Marseille Universite, CNRS, ISM UMR 7287, Marseille (France); Radiology Department, APHM, Marseille (France)

2017-02-15

To investigate radiation dose and diagnostic performance of C-arm flat-panel CT (FPCT) versus standard multi-detector CT (MDCT) shoulder arthrography using MRI-arthrography as reference standard. Radiation dose of two different FPCT acquisitions (5 and 20 s) and standard MDCT of the shoulder were assessed using phantoms and thermoluminescence dosimetry. FPCT arthrographies were performed in 34 patients (mean age 44 ± 15 years). Different joint structures were quantitatively and qualitatively assessed by two independent radiologists. Inter-reader agreement and diagnostic performance were calculated. Effective radiation dose was markedly lower in FPCT 5 s (0.6 mSv) compared to MDCT (1.7 mSv) and FPCT 20 s (3.4 mSv). Contrast-to-noise ratios (CNRs) were significantly (p < 0.05) higher in FPCT 20-s versus 5-s protocols. Inter-reader agreements of qualitative ratings ranged between κ = 0.47-1.0. Sensitivities for cartilage and rotator cuff pathologies were low for FPCT 5-s (40 % and 20 %) and moderate for FPCT 20-s protocols (75 % and 73 %). FPCT showed high sensitivity (81-86 % and 89-99 %) for bone and acromioclavicular-joint pathologies. Using a 5-s protocol FPCT shoulder arthrography provides lower radiation dose compared to MDCT but poor sensitivity for cartilage and rotator cuff pathologies. FPCT 20-s protocol is moderately sensitive for cartilage and rotator cuff tendon pathology with markedly higher radiation dose compared to MDCT. (orig.)

Optimised intake stroke analysis for flat and dome head pistons ...

African Journals Online (AJOL)

Optimised intake stroke analysis for flat and dome head pistons. ... in understanding the performance characteristics optioned between flat head and dome head pistons in engine design. ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

The Virtual Fields Method Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements

CERN Document Server

Pierron, Fabrice

2012-01-01

The Virtual Fields Method: Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements is the first book on the Virtual Fields Method (VFM), a technique to identify materials mechanical properties from full-field measurements. Firmly rooted with extensive theoretical description of the method, the book presents numerous examples of application to a wide range of materials (composites, metals, welds, biomaterials) and situations (static, vibration, high strain rate). The authors give a detailed training section with examples of progressive difficulty to lead the reader to program the VFM and include a set of commented Matlab programs as well as GUI Matlab-based software for more general situations. The Virtual Fields Method: Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements is an ideal book for researchers, engineers, and students interested in applying the VFM to new situations motivated by their research.  

Magnetized and Flat Beam Experiment at FAST

Energy Technology Data Exchange (ETDEWEB)

Halavanau, A. [Fermilab; Hyun, J. [Sokendai, Tsukuba; Mihalcea, D. [NIU, DeKalb; Piot, P. [NICADD, DeKalb; Sen, T. [Fermilab; Thangaraj, C. [Fermilab

2017-05-22

A photocathode, immersed in solenoidal magnetic field, can produce canonical-angular-momentum (CAM) dominated or “magnetized” electron beams. Such beams have an application in electron cooling of hadron beams and can also be uncoupled to yield asymmetric-emittance (“flat”) beams. In the present paper we explore the possibilities of the flat beam generation at Fermilab’s Accelerator Science and Technology (FAST) facility. We present optimization of the beam flatness and four-dimensional transverse emittance and investigate the mapping and its limitations of the produced eigen-emittances to conventional emittances using a skew-quadrupole channel. Possible application of flat beams at the FAST facility are also discussed.

PERBANDINGAN UNJUK KERJA ANTARA PANEL SEL SURYA BERPENJEJAK DENGAN PANEL SEL SURYA DIAM

Directory of Open Access Journals (Sweden)

Syafaruddin Ch

2010-07-01

Full Text Available The ability to produce electrical energy at Solar Power Plant  is highly dependent on the magnitude and duration of sun exposure on the solar cell panels. The movement of the sun from east to west that periodicity in every day is a problem at  the  optimization generation of electricity at  Solar Power Plant   if using solar panel that motionless. This is because the solar cell panel can not catch the maximum sun exposure. To solve the above problem then designed a solar cell panel  tracker  capable of follo-wing the movements of the sun. Then conducted a test to see the performance of solar cell pa-nel  tracker  and compare it with the performance of solar cell panel was motionless. The testing doing along 6 days, with way to irradiate the panel of solar cells  tracker  and panels of solar cell motionless with sun exposure  along a  full day. Then the electric current generated each panel were recorded. The comparison of current then generating comparison of electric power delivery. The result show that the solar cell panel  tracker  produce the average current is 2.19 A whereas solar-cell panel still 1.97 A.  This result   indicate that average power for solar cell panel  tracker  39.41 W while for solar cell panel that motionless is  35.46 W. These results indicate that the performance of solar cell panel  tracker  better than  solar cell panel motionless.

Effects of fire retardants on physical, mechanical, and fire properties of flat-pressed WPCs

Science.gov (United States)

Nadir Ayrilmis; Jan T. Benthien; Heiko Thoemen; Robert H. White

2012-01-01

Physical, mechanical, and fire properties of the flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (10% by weight) at different levels of wood flour (WF) content, 40, 50, or 60 wt%, were investigated. The WPC panels were made from dry-blended WF, polypropylene (PP), and fire retardant (FR) powders with maleic anhydride-grafted PP (2...

Can Integrated Micro-Optical Concentrator Technology Revolutionize Flat-Plate Photovoltaic Solar Energy Harvesting?

Science.gov (United States)

Haney, Michael W.

2015-12-01

The economies-of-scale and enhanced performance of integrated micro-technologies have repeatedly delivered disruptive market impact. Examples range from microelectronics to displays to lighting. However, integrated micro-scale technologies have yet to be applied in a transformational way to solar photovoltaic panels. The recently announced Micro-scale Optimized Solar-cell Arrays with Integrated Concentration (MOSAIC) program aims to create a new paradigm in solar photovoltaic panel technology based on the incorporation of micro-concentrating photo-voltaic (μ-CPV) cells. As depicted in Figure 1, MOSAIC will integrate arrays of micro-optical concentrating elements and micro-scale PV elements to achieve the same aggregated collection area and high conversion efficiency of a conventional (i.e., macro-scale) CPV approach, but with the low profile and mass, and hopefully cost, of a conventional non-concentrated PV panel. The reduced size and weight, and enhanced wiring complexity, of the MOSAIC approach provide the opportunity to access the high-performance/low-cost region between the conventional CPV and flat-plate (1-sun) PV domains shown in Figure 2. Accessing this portion of the graph in Figure 2 will expand the geographic and market reach of flat-plate PV. This talk reviews the motivation and goals for the MOSAIC program. The diversity of the technical approaches to micro-concentration, embedded solar tracking, and hybrid direct/diffuse solar resource collection found in the MOSAIC portfolio of projects will also be highlighted.

Software Simulates Sight: Flat Panel Mura Detection

Science.gov (United States)

2008-01-01

In the increasingly sophisticated world of high-definition flat screen monitors and television screens, image clarity and the elimination of distortion are paramount concerns. As the devices that reproduce images become more and more sophisticated, so do the technologies that verify their accuracy. By simulating the manner in which a human eye perceives and interprets a visual stimulus, NASA scientists have found ways to automatically and accurately test new monitors and displays. The Spatial Standard Observer (SSO) software metric, developed by Dr. Andrew B. Watson at Ames Research Center, measures visibility and defects in screens, displays, and interfaces. In the design of such a software tool, a central challenge is determining which aspects of visual function to include while accuracy and generality are important, relative simplicity of the software module is also a key virtue. Based on data collected in ModelFest, a large cooperative multi-lab project hosted by the Optical Society of America, the SSO simulates a simplified model of human spatial vision, operating on a pair of images that are viewed at a specific viewing distance with pixels having a known relation to luminance. The SSO measures the visibility of foveal spatial patterns, or the discriminability of two patterns, by incorporating only a few essential components of vision. These components include local contrast transformation, a contrast sensitivity function, local masking, and local pooling. By this construction, the SSO provides output in units of "just noticeable differences" (JND) a unit of measure based on the assumed smallest difference of sensory input detectable by a human being. Herein is the truly amazing ability of the SSO, while conventional methods can manipulate images, the SSO models human perception. This set of equations actually defines a mathematical way of working with an image that accurately reflects the way in which the human eye and mind behold a stimulus. The SSO is

Public involvement and risk communiction for the Rocky Flats health studies

International Nuclear Information System (INIS)

Zoda, S.M.; Lockhart, A.J.

1993-01-01

In 1990, the State of Colorado and the U.S. Department of Energy entered into an Agreement in Principle that provides funding for state studies and monitoring of the Rocky Flats Nuclear Weapons Plant. The Colorado Department of Health initiated a two-phase study to identify releases of radioactive and other contaminants from the year 1952, when Rocky Flats opened, through 1989, and to estimate the potential offsite exposures and health effects. Because one of the main goals for the study is to answer citizen questions about past operations and impacts from the Rocky Flats Plant, the Department of Health designed an open study process featuring a multi-faceted program for public involvement and two-way communication. To provide independent scientific oversight and increase public accountability, Governor Roy Romer appointed a 12-member Health Advisory Panel that includes local and national technical experts and community members. This paper describes the study process and the public involvement and risk communication program designed to address citizen concerns, foster understanding and build credibility

An epidemiologic study of flat foot in Iran

Directory of Open Access Journals (Sweden)

Alamy B

1997-07-01

Full Text Available Among 880 studied feet of 7-14 years old children 6.9% suffered mild and severe flat foot. 53.8% of the affected children were symptomatic. As 40.1% of the general population experiences symptoms, in a small proportion of affected persons, symptoms are due to flat foot. The prevalence of symptoms rises with increasing severity of the disorder. In this article, reviewing general aspects of flat food, prevalence and other epidemiological aspects of flat foot for the first time in Iran have been presented

Lens Systems Incorporating A Zero Power Corrector Part 3 New Four-Element Microscope Objectives With Flat Field Or High Power

Science.gov (United States)

Klee, H. W.; McDowell, M. W.

1986-02-01

The use of the zero power corrector concept has been extended to the design of microscope objectives. Several four and five-element designs are described which include a flat field 10x design of 0.25 numerical aperture and a 40x design of 0.65 numerical aperture.

Evaluation of patient exposure with Flat Panel Detector (FPD) in X-ray TV system

International Nuclear Information System (INIS)

Yamada, M.; Komiya, N.; Kawaguchi, A.; Suzuki, M.; Suzuki, Shoichi; Asada, Yasuki

2008-01-01

The use of flat-panel detector (FPD) systems in TV equipment for gastrointestinal tract examination is increasing. The use of FPD systems is believed to reduce the exposure dose. When our institution changed its TV equipment from an image intensifier (GE; MS90Tj) system to an FPD (Shimadzu; SONIALVISION safire DAR-3500) system, we measured the doses produced and carried out a comparative examination of the extent to which exposure could be reduced. Two TV systems were used. We used an analyzer to measure output waveform, tube voltage, and half-value layer (HVL), and an ionization chamber dosimeter to carry out dose-in-air measurements. Body thickness, number of image acquisitions, and fluoroscopy time are required for the calculation of entrance skin dose (ESD). We therefore measured body thicknesses in 1000 upper gastrointestinal tract (UGI) and barium enemas and obtained average body thicknesses for males and females by age group. Values used for number of image acquisitions and fluoroscopy times were the averages in our institution over a two-year period. When an I.I. system was used, the average ESD during UGI examination were 126.8 mGy fluoroscopy dose and 11.62 mGy imaging dose, for an average total dose of 138.42 mGy per examination. ESD during barium enema averaged 201.73 mGy fluoroscopy dose and 45.2 mGy imaging dose, for an average total dose of 246.92 mGy per examination. When an FPD system was used, the average ESD during UGI examination were 58.71 mGy fluoroscopy dose and 5.72 mGy imaging dose, for an average total dose of 64.43 mGy per examination. ESD during barium enema averaged 112.21 mGy fluoroscopy dose and 24.55 mGy imaging dose, for an average total dose of 136.76 mGy per examination. The use of an FPD system reduced both fluoroscopy dose and imaging dose by 50%. The number of TV systems equipped with FPD in Japan has increased from around 1300 in 2006 to around 1700 in 2007. The use of FPD systems can be expected to increase in future. This

Optimization of a flat-panel based real time dual-energy system for cardiac imaging

International Nuclear Information System (INIS)

Ducote, Justin L.; Xu Tong; Molloi, Sabee

2006-01-01

A simulation study was conducted to evaluate the effects of high-energy beam filtration, dual-gain operation and noise reduction on dual-energy images using a digital flat-panel detector. High-energy beam filtration increases image contrast through greater beam separation and tends to reduce total radiation exposure and dose per image pair. It is also possible to reduce dual-energy image noise by acquiring low and high-energy images at two different detector gains. In addition, dual-energy noise reduction algorithms can further reduce image noise. The cumulative effect of these techniques applied in series was investigated in this study. The contrast from a small thickness of calcium was simulated over a step phantom of tissue equivalent material with a CsI phosphor as the image detector. The dual-energy contrast-to-noise ratio was calculated using values of energy absorption and energy variance. A figure-of-merit (FOM) was calculated from dual-energy contrast-to-noise ratio (CNR) and patient effective dose estimated from values of entrance exposure. Filter atomic numbers in the range of 1-100 were considered with thicknesses ranging from 0-2500 mg/cm 2 . The simulation examined combinations of the above techniques which maximized the FOM. The application of a filter increased image contrast by as much as 45%. Near maximal increases were seen for filter atomic numbers in the range of 40-60 and 85-100 with masses above 750 mg/cm 2 . Increasing filter thickness beyond 1000 mg/cm 2 increased tube loading without further significant contrast enhancement. No additional FOM improvements were seen with dual gain before or after the application of any noise reduction algorithm. Narrow beam experiments were carried out to verify predictions. The measured FOM increased by more than a factor of 3.5 for a silver filter thickness of 800 μm, equal energy weighting and application of a noise clipping algorithm. The main limitation of dynamic high-energy filtration is increased

Percutaneous sacroplasty with the use of C-arm flat-panel detector CT: technical feasibility and clinical outcome

International Nuclear Information System (INIS)

Kang, Sung Eun; Lee, Joon Woo; Kim, Joo Hyung; Kang, Heung Sik; Park, Kun Woo; Yeom, Jin S.

2011-01-01

Sacroplasty for sacral insufficiency fractures (SIFs) has been performed mostly under computed tomography (CT) or fluoroscopy guidance. The purposes of this study are to describe technical tips and clinical outcomes of sacroplasty under C-arm flat panel detector CT (C-arm CT) guidance, and to compare the cement distributions shown on C-arm CT with those on multi-detector CT (MDCT). This study consisted of patients who underwent sacroplasty for SIF using C-arm CT from May 2006 to May 2009. Technical success was assessed in terms of cement filling and leakage. Clinical outcome was assessed at short-term (less than 1 month) and long-term (more than 1 month) follow-up using a four-grade patient satisfaction scale: poor, fair, good, and excellent. After sacroplasty, all patients underwent MDCT and three radiologists compared MDCT images with C-arm CT images in consensus, focusing on the cement distribution and cement leakage. Sacroplasties were performed on both sacral alae in all 8 patients (male:female = 2:6, mean age = 76.9, range = 63-82). The technical success rate was 100%. At short-term follow up, 6 patients (87.5%) reported significant improvement. Five patients (62.5%) were available for long-term follow-up and all 5 patients reported a reduced pain and an improved ability to ambulate. Using MDCT as the standard of reference, the cement distribution was visualized equally well by C-arm CT. Sacroplasty under C-arm CT showed excellent technical success and good clinical outcome. There was an excellent correlation between C-arm CT and MDCT in evaluating cement distribution and cement leakage. (orig.)

Percutaneous sacroplasty with the use of C-arm flat-panel detector CT: technical feasibility and clinical outcome

Energy Technology Data Exchange (ETDEWEB)

Kang, Sung Eun; Lee, Joon Woo; Kim, Joo Hyung; Kang, Heung Sik [Seoul National University Bundang Hospital, Department of Radiology, Gyeonggi-do (Korea, Republic of); Park, Kun Woo; Yeom, Jin S. [Seoul National University Bundang Hospital, Department of Orthopaedic Surgery, Gyeonggi-do (Korea, Republic of)

2011-04-15

Sacroplasty for sacral insufficiency fractures (SIFs) has been performed mostly under computed tomography (CT) or fluoroscopy guidance. The purposes of this study are to describe technical tips and clinical outcomes of sacroplasty under C-arm flat panel detector CT (C-arm CT) guidance, and to compare the cement distributions shown on C-arm CT with those on multi-detector CT (MDCT). This study consisted of patients who underwent sacroplasty for SIF using C-arm CT from May 2006 to May 2009. Technical success was assessed in terms of cement filling and leakage. Clinical outcome was assessed at short-term (less than 1 month) and long-term (more than 1 month) follow-up using a four-grade patient satisfaction scale: poor, fair, good, and excellent. After sacroplasty, all patients underwent MDCT and three radiologists compared MDCT images with C-arm CT images in consensus, focusing on the cement distribution and cement leakage. Sacroplasties were performed on both sacral alae in all 8 patients (male:female = 2:6, mean age = 76.9, range = 63-82). The technical success rate was 100%. At short-term follow up, 6 patients (87.5%) reported significant improvement. Five patients (62.5%) were available for long-term follow-up and all 5 patients reported a reduced pain and an improved ability to ambulate. Using MDCT as the standard of reference, the cement distribution was visualized equally well by C-arm CT. Sacroplasty under C-arm CT showed excellent technical success and good clinical outcome. There was an excellent correlation between C-arm CT and MDCT in evaluating cement distribution and cement leakage. (orig.)

Introduction of beam flatness filter for 60Co teletherapy beam and its efficacy in clinical radiotherapy

International Nuclear Information System (INIS)

Sathiyan, S.; Ravichandran, R.; Ravikumar, M.

2003-01-01

In the western countries cobalt-60 machines have become obsolete, whereas in India we have about 250 machines operational for clinical radiotherapy. The basic differences of 6 MV x-ray beam and cobalt-60 beam are: a) build-up d max point, b) flatness of beam at depths, and c) sharpness of the beam edge. We looked at the homogeneity of delivered dose in the target volume in a 3 field SAD technique for 60 Co (80 cm, 100 cm) and 6 MV treatments. More dose variations are seen in 60 Co treated volume. The excess curvature of isodose curves of 60 Co at depths may be one of the reasons for this inhomogeneity in dose to target volume. Therefore, there is need for achieving perfect flatness in the isodose curves at desired depths. A flattening filter was fabricated using dental wax impression material to account for depths of curvature of 50% 60 Co isodose curve. The filter was fabricated for the Theratron 780C machine for necessary flatness. The beam flatness with filter was measured with a) ionization and b) TL dosimetry methods. The flattened beam profile was compared with 6 MV x-ray beam (Clinac-1800, M/s Varian, USA). Our measurements show uniform flatness of cobalt-60 isodose curve at desired depth and useful radiation field width comparable to 6 MV x-ray photon profile at full width at half maximum (FWHM). If this concept is extendable to short field widths, it appears that there is scope for use of such filter in the treatments of oesophagus, larynx, and pituitary tumours to achieve dose homogeneity. Using this flatness filter and penumbra trimmer, we may achieve better quality cobalt-60 beam for radiotherapy. (author)

Method of gas emission control for safe working of flat gassy coal seams

Science.gov (United States)

Vinogradov, E. A.; Yaroshenko, V. V.; Kislicyn, M. S.

2017-10-01

The main problems at intensive flat gassy coal seam longwall mining are considered. For example, mine Kotinskaja JSC “SUEK-Kuzbass” shows that when conducting the work on the gassy coal seams, methane emission control by means of ventilation, degassing and insulated drain of methane-air mixture is not effective and stable enough. It is not always possible to remove the coal production restrictions by the gas factor, which leads to financial losses because of incomplete using of longwall equipment and the reduction of the technical and economic indicators of mining. To solve the problems, the authors used a complex method that includes the compilation and analysis of the theory and practice of intensive flat gassy coal seam longwall mining. Based on the results of field and numerical researches, the effect of parameters of technological schemes on efficiency of methane emission control on longwall panels, the non-linear dependence of the permissible according to gas factor longwall productivity on parameters of technological schemes, ventilation and degassing during intensive mining flat gassy coal seams was established. The number of recommendations on the choice of the location and the size of the intermediate section of coal heading to control gassing in the mining extracted area, and guidelines for choosing the parameters of ventilation of extracted area with the help of two air supply entries and removal of isolated methane-air mixture are presented in the paper. The technological scheme, using intermediate entry for fresh air intake, ensuring effective management gassing and allowing one to refuse from drilling wells from the surface to the mined-out space for mining gas-bearing coal seams, was developed.

Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation.

Science.gov (United States)

Zhang, Jinke; Williams, Bryan M; Lawman, Samuel; Atkinson, David; Zhang, Zijian; Shen, Yaochun; Zheng, Yalin

2017-08-07

Automotive coating systems are designed to protect vehicle bodies from corrosion and enhance their aesthetic value. The number, size and orientation of small metallic flakes in the base coat of the paint has a significant effect on the appearance of automotive bodies. It is important for quality assurance (QA) to be able to measure the properties of these small flakes, which are approximately 10μm in radius, yet current QA techniques are limited to measuring layer thickness. We design and develop a time-domain (TD) full-field (FF) optical coherence tomography (OCT) system to scan automotive panels volumetrically, non-destructively and without contact. We develop and integrate a segmentation method to automatically distinguish flakes and allow measurement of their properties. We test our integrated system on nine sections of five panels and demonstrate that this integrated approach can characterise small flakes in automotive coating systems in 3D, calculating the number, size and orientation accurately and consistently. This has the potential to significantly impact QA testing in the automotive industry.

Flat detectors and their clinical applications

International Nuclear Information System (INIS)

Spahn, Martin

2005-01-01

Diagnostic and interventional flat detector X-ray systems are penetrating the market in all application segments. First introduced in radiography and mammography, they have conquered cardiac and general angiography and are getting increasing attention in fluoroscopy. Two flat detector technologies prevail. The dominating method is based on an indirect X-ray conversion process, using cesium iodide scintillators. It offers considerable advantages in radiography, angiography and fluoroscopy. The other method employs a direct converter such as selenium which is particularly suitable for mammography. Both flat detector technologies are based on amorphous silicon active pixel matrices. Flat detectors facilitate the clinical workflow in radiographic rooms, foster improved image quality and provide the potential to reduce dose. This added value is based on their large dynamic range, their high sensitivity to X-rays and the instant availability of the image. Advanced image processing is instrumental in these improvements and expand the range of conventional diagnostic methods. In angiography and fluoroscopy the transition from image intensifiers to flat detectors is facilitated by ample advantages they offer, such as distortion-free images, excellent coarse contrast, large dynamic range and high X-ray sensitivity. These characteristics and their compatibility with strong magnetic fields are the basis for improved diagnostic methods and innovative interventional applications. (orig.)

Edge-Spread Functions Expected for Several Changes in a Commercial Flat-Panel System

International Nuclear Information System (INIS)

Schach von Wittenau, A E

2002-01-01

The Bldg. 239 radiography facility uses a 9 MeV bremsstrahlung linac and a commercially available fiat-panel detector system. Ref. [1] discusses the facility in detail. Ref. [1] furthermore discusses the imaging quality of the fiat-panel system, and identifies several sources of image blur for the system in question. The maim'' contributors to the imaging blur are radiation scattered from the front cover of the detector housing, radiation scattered from the back cover of the detector housing, and radiation scattered from the aluminum plate that supports the amorphous-Si detector within the detector housing. The manufacturer of one such fiat-panel system seems willing to modify one of their products as requested, if such modifications may be made easily. Easy modifications would include making the detector housing thinner, decreasing the sizes of air gaps inside tile detector system, etc. Removing the aluminum support plate is considered to be a difficult modification. This memo reports the results of a set of Monte Carlo simulations that were performed to predict the changes in imaging quality, compared to that of the current system, if the detector is modified as suggested above. In particular, the edge-spread function (ESF) was calculated for each modification. ESFs were calculated for three photon energies: 100 keV, 450 keV, and 3 MeV. The results suggest that thinning and moving tile front and back covers of the detector housing should result in improved image quality for all of the photon energies considered. Interestingly, the results also suggest that removing the aluminum support plate would improve tim imaging performance at 100 keV and 450 keV, but that removing the plate has no additional benefit for imaging with 3 MeV photons

Engineering flat electronic bands in quasiperiodic and fractal loop geometries

Energy Technology Data Exchange (ETDEWEB)

Nandy, Atanu, E-mail: atanunandy1989@gmail.com; Chakrabarti, Arunava, E-mail: arunava_chakrabarti@yahoo.co.in

2015-11-06

Exact construction of one electron eigenstates with flat, non-dispersive bands, and localized over clusters of various sizes is reported for a class of quasi-one-dimensional looped networks. Quasiperiodic Fibonacci and Berker fractal geometries are embedded in the arms of the loop threaded by a uniform magnetic flux. We work out an analytical scheme to unravel the localized single particle states pinned at various atomic sites or over clusters of them. The magnetic field is varied to control, in a subtle way, the extent of localization and the location of the flat band states in energy space. In addition to this we show that an appropriate tuning of the field can lead to a re-entrant behavior of the effective mass of the electron in a band, with a periodic flip in its sign. - Highlights: • Exact construction of eigenstates with flat and dispersive bands is reported. • Competition between translational order and growth of aperiodicity is discussed. • The effect of magnetic field on the location of flat band states is shown. • Flux tunable re-entrant behavior of the effective mass of electron is studied.

Owhership of flats

OpenAIRE

Přibil, Jan

2012-01-01

Ownership of Flats Summary In his diploma thesis "Ownership of Flats", the author focuses on applicable law of flat ownership in the Czech Republic, especially the Flat Ownership Act 72/1994 Sb. The author puts the contemporary regulation in historical context; he describes the theoretical principles underlining the current applicable law and defines in detail the basic legal terms used by the Flat Ownership Act. Original and derivative forms of flat ownership acquisition are explained, namel...

A soft X-Ray flat field grating spectrograph and its experimental applications

International Nuclear Information System (INIS)

Ni Yuanlong; Mao Chusheng

2001-01-01

The principle, structure, and application results of a flat field grating spectrograph for X-ray laser research is presented. There are two kinds of the spectrograph. One uses a varied space grating with nominal line spacing 1200 l/mm, the spectral detection range is 5 - 50 nm, and another uses a 2400 l/mm varied line space grating, detection range is 1 - 10 nm. The experimental results of the former is introduced only. Both experimental results of this instrument using the soft X-ray film and a streak camera as the detecting elements are given. The spectral resolutions are 0.01 nm and 0.05 nm, respectively. The temporal resolution is 30 ps. Finally, the stigmatic structure of the spectrograph is introduced, which uses cylindrical mirror and spherical mirror as a focusing system. The magnification is 5, spatial resolution is 25 μm. The experimental results are given as well

Breast imaging using an amorphous silicon-based full-field digital mammographic system: stability of a clinical prototype.

Science.gov (United States)

Vedantham, S; Karellas, A; Suryanarayanan, S; D'Orsi, C J; Hendrick, R E

2000-11-01

An amorphous silicon-based full-breast imager for digital mammography was evaluated for detector stability over a period of 1 year. This imager uses a structured CsI:TI scintillator coupled to an amorphous silicon layer with a 100-micron pixel pitch and read out by special purpose electronics. The stability of the system was characterized using the following quantifiable metrics: conversion factor (mean number of electrons generated per incident x-ray), presampling modulation transfer function (MTF), detector linearity and sensitivity, detector signal-to-noise ratio (SNR), and American College of Radiology (ACR) accreditation phantom scores. Qualitative metrics such as flat field uniformity, geometric distortion, and Society of Motion Picture and Television Engineers (SMPTE) test pattern image quality were also used to study the stability of the system. Observations made over this 1-year period indicated that the maximum variation from the average of the measurements were less than 0.5% for conversion factor, 3% for presampling MTF over all spatial frequencies, 5% for signal response, linearity and sensitivity, 12% for SNR over seven locations for all 3 target-filter combinations, and 0% for ACR accreditation phantom scores. ACR mammographic accreditation phantom images indicated the ability to resolve 5 fibers, 4 speck groups, and 5 masses at a mean glandular dose of 1.23 mGy. The SMPTE pattern image quality test for the display monitors used for image viewing indicated ability to discern all contrast steps and ability to distinguish line-pair images at the center and corners of the image. No bleeding effects were observed in the image. Flat field uniformity for all 3 target-filter combinations displayed no artifacts such as gridlines, bad detector rows or columns, horizontal or vertical streaks, or bad pixels. Wire mesh screen images indicated uniform resolution and no geometric distortion.

Three-Dimensional Exact Free Vibration Analysis of Spherical, Cylindrical, and Flat One-Layered Panels

Directory of Open Access Journals (Sweden)

Salvatore Brischetto

2014-01-01

equilibrium written in orthogonal curvilinear coordinates for the free vibrations of simply supported structures. These equations consider an exact geometry for shells without simplifications. The main novelty is the possibility of a general formulation for different geometries. The equations written in general orthogonal curvilinear coordinates allow the analysis of spherical shell panels and they automatically degenerate into cylindrical shell panel, cylindrical closed shell, and plate cases. Results are proposed for isotropic and orthotropic structures. An exhaustive overview is given of the vibration modes for a number of thickness ratios, imposed wave numbers, geometries, embedded materials, and angles of orthotropy. These results can also be used as reference solutions to validate two-dimensional models for plates and shells in both analytical and numerical form (e.g., closed solutions, finite element method, differential quadrature method, and global collocation method.

An Irrotational Flow Field That Approximates Flat Plate Boundary Conditions

OpenAIRE

Ruffa, Anthony A.

2004-01-01

An irrotational solution is derived for the steady-state Navier-Stokes equations that approximately satisfies the boundary conditions for flow over a finite flat plate. The nature of the flow differs substantially from boundary layer flow, with severe numerical difficulties in some regions.

Suspicious amorphous microcalcifications detected on full-field digital mammography: correlation with histopathology

Directory of Open Access Journals (Sweden)

Vera Christina Camargo de Siqueira Ferreira

2018-03-01

Full Text Available Abstract Objective: To evaluate suspicious amorphous calcifications diagnosed on full-field digital mammography (FFDM and establish correlations with histopathology findings. Materials and Methods: This was a retrospective study of 78 suspicious amorphous calcifications (all classified as BI-RADS® 4 detected on FFDM. Vacuum-assisted breast biopsy (VABB was performed. The histopathological classification of VABB core samples was as follows: pB2 (benign; pB3 (uncertain malignant potential; pB4 (suspicion of malignancy; and pB5 (malignant. Treatment was recommended for pB5 lesions. To rule out malignancy, surgical excision was recommended for pB3 and pB4 lesions. Patients not submitted to surgery were followed for at least 6 months. Results: Among the 78 amorphous calcifications evaluated, the histopathological analysis indicated that 8 (10.3% were malignant/suspicious (6 classified as pB5 and 2 classified as pB4 and 36 (46.2% were benign (classified as pB2. The remaining 34 lesions (43.6% were classified as pB3: 33.3% were precursor lesions (atypical ductal hyperplasia, lobular neoplasia, or flat epithelial atypia and 10.3% were high-risk lesions. For the pB3 lesions, the underestimation rate was zero. Conclusion: The diagnosis of precursor lesions (excluding atypical ductal hyperplasia, which can be pB4 depending on the severity and extent of the lesion should not necessarily be considered indicative of underestimation of malignancy. Suspicious amorphous calcifications correlated more often with precursor lesions than with malignant lesions, at a ratio of 3:1.

Calibration and validation of full-field techniques

Directory of Open Access Journals (Sweden)

Thalmann R.

2010-06-01

Full Text Available We review basic metrological terms related to the use of measurement equipment for verification of numerical model calculations. We address three challenges that are faced when performing measurements in experimental mechanics with optical techniques: the calibration of a measuring instrument that (i measures strain values, (ii provides full-field data, and (iii is dynamic.

Holography and Entanglement in Flat Spacetime

International Nuclear Information System (INIS)

Li Wei; Takayanagi, Tadashi

2011-01-01

We propose a holographic correspondence of the flat spacetime based on the behavior of the entanglement entropy and the correlation functions. The holographic dual theory turns out to be highly nonlocal. We argue that after most part of the space is traced out, the reduced density matrix gives the maximal entropy and the correlation functions become trivial. We present a toy model for this holographic dual using a nonlocal scalar field theory that reproduces the same property of the entanglement entropy. Our conjecture is consistent with the entropy of Schwarzschild black holes in asymptotically flat spacetimes.

STUDYING DEFORMATIONS OF AN FLAT TRUSS STRUCTURE STATICALLY INDETERMINATED EXTERNALLY

Directory of Open Access Journals (Sweden)

Kirsanov Mikhail Nikolaevich

2017-08-01

Full Text Available A flat statically determinate parallel-chord truss structure has a cross-shaped grid and rests upon two rigid pin-bearing supports. Loads in bars are determined in a symbol form using the method of joint isolation by the computer mathematics Maple system. The peculiarity of the considered truss structure is its external static indeterminacy. In fact, all efforts and reactions of supports can be determined from the equilibrium conditions. But the inconvenience is necessary to consider the equilibrium of all the nodes of the truss. The Ritter cross-section method is not applicable to this truss structure. The sections that cut the truss into two parts and pass through the three rods, here exist only for several rods of the extreme panels. The purpose of this paper is to calculate a truss structure with a different number of panels in analytical and numerical form. Finite element calculation method with the use of software LISA 8.0 is applied. It’s noted that a truss structure is kinetically changeable when the number of spans is odd. The corresponding plan of probable velocities is given. In order to receive analytic dependence of deflection on the span number, the induction method and Maxwell-Moor formula has been applied. The operators of the compilation and solution of recurrence equations are involved in determining the general terms of the coefficient sequences. The formulas for calculation of loads in the most compressed bars of a truss structure were received.

Generation of shape-invariant flat-top laser beams

CSIR Research Space (South Africa)

Ait-Ameur, K

2015-02-01

Full Text Available A great number of laser applications need in place of the usual Gaussian beam a flat-top intensity profile in the focal plane of a focusing lens. In general the transformation of the laser beam from the Gaussian to the flat-top shape is made by a...

Development of Partial Tubular Flat Knitting Fabric Composite Preform

Directory of Open Access Journals (Sweden)

Jiang Wei Qing

2016-01-01

Full Text Available After building some structures of partial tubular flat knitting fabric composite preform, the influencing factor on tubular section was analyzed and the fabric was knitted selectively. The partial tubular flat knitting fabric composite preform were Knitted by changing different yarn, row number and two-sided partial tubular flat knitting fabric. Multilayer sheet would be got after hot pressing and it has big market prospects and good application value.

Design and analysis of all-dielectric subwavelength focusing flat lens

Science.gov (United States)

Turduev, M.; Bor, E.; Kurt, H.

2017-09-01

In this letter, we numerically designed and experimentally demonstrated a compact photonic structure for the subwavelength focusing of light using all-dielectric absorption-free and nonmagnetic scattering objects distributed in an air medium. In order to design the subwavelength focusing flat lens, an evolutionary algorithm is combined with the finite-difference time-domain method for determining the locations of cylindrical scatterers. During the multi-objective optimization process, a specific objective function is defined to reduce the full width at half maximum (FWHM) and diminish side lobe level (SLL) values of light at the focal point. The time-domain response of the optimized flat lens exhibits subwavelength light focusing with an FWHM value of 0.19λ and an SLL value of 0.23, where λ denotes the operating wavelength of light. Experimental analysis of the proposed flat lens is conducted in a microwave regime and findings exactly verify the numerical results with an FWHM of 0.192λ and an SLL value of 0.311 at the operating frequency of 5.42 GHz. Moreover, the designed flat lens provides a broadband subwavelength focusing effect with a 9% bandwidth covering frequency range of 5.10 GHz-5.58 GHz, where corresponding FWHM values remain under 0.21λ. Also, it is important to note that the designed flat lens structure performs a line focusing effect. Possible applications of the designed structure in telecom wavelengths are speculated upon for future perspectives. Namely, the designed structure can perform well in photonic integrated circuits for different fields of applications such as high efficiency light coupling, imaging and optical microscopy, with its compact size and ability for strong focusing.

Novel Na(+) doped Alq3 hybrid materials for organic light-emitting diode (OLED) devices and flat panel displays.

Science.gov (United States)

Bhagat, S A; Borghate, S V; Kalyani, N Thejo; Dhoble, S J

2015-05-01

Pure and Na(+) -doped Alq3 complexes were synthesized by a simple precipitation method at room temperature, maintaining a stoichiometric ratio. These complexes were characterized by X-ray diffraction, Fourier transform infrared (FTIR), UV/Vis absorption and photoluminescence (PL) spectra. The X-ray diffractogram exhibits well-resolved peaks, revealing the crystalline nature of the synthesized complexes, FTIR confirms the molecular structure and the completion of quinoline ring formation in the metal complex. UV/Vis absorption and PL spectra of sodium-doped Alq3 complexes exhibit high emission intensity in comparison with Alq3 phosphor, proving that when doped in Alq3 , Na(+) enhances PL emission intensity. The excitation spectra of the synthesized complexes lie in the range 242-457 nm when weak shoulders are also considered. Because the sharp excitation peak falls in the blue region of visible radiation, the complexes can be employed for blue chip excitation. The emission wavelength of all the synthesized complexes lies in the bluish green/green region ranging between 485 and 531 nm. The intensity of the emission wavelength was found to be elevated when Na(+) is doped into Alq3 . Because both the excitation and emission wavelengths fall in the visible region of electromagnetic radiation, these phosphors can also be employed to improve the power conversion efficiency of photovoltaic cells by using the solar spectral conversion principle. Thus, the synthesized phosphors can be used as bluish green/green light-emitting phosphors for organic light-emitting diodes, flat panel displays, solid-state lighting technology - a step towards the desire to reduce energy consumption and generate pollution free light. Copyright © 2014 John Wiley & Sons, Ltd.

Magnetic evaluation of a solar panel using HTS-SQUID

Energy Technology Data Exchange (ETDEWEB)

Kiwa, Toshihiko, E-mail: kiwa@okayama-u.ac.jp; Fukudome, Yohei; Miyazaki, Shingo; Saari, Mohd Mawardi; Sakai, Kenji; Tsukada, Keiji

2013-11-15

Highlights: •The magnetic evaluation system of a solar panel using HTS-SQUID has been developed. •The electric circuits made by the discrete devices on the circuit board were visualized. •The electric properties of the commercial solar panels were demonstrated. -- Abstract: The magnetic evaluation system of a solar panel using HTS-SQUID has been proposed and developed. A normal pick-up coil was applied to detect the tangential magnetic field to the panel surface. Since the detected field could be related to the currents of the solar panels, the electric properties of the solar panels could be evaluated. In this work, the evaluation of the electric properties of the commercial solar panels as well as the electric circuits made by the discrete devices on the circuit board was visualized.

Magnetic evaluation of a solar panel using HTS-SQUID

International Nuclear Information System (INIS)

Kiwa, Toshihiko; Fukudome, Yohei; Miyazaki, Shingo; Saari, Mohd Mawardi; Sakai, Kenji; Tsukada, Keiji

2013-01-01

Highlights: •The magnetic evaluation system of a solar panel using HTS-SQUID has been developed. •The electric circuits made by the discrete devices on the circuit board were visualized. •The electric properties of the commercial solar panels were demonstrated. -- Abstract: The magnetic evaluation system of a solar panel using HTS-SQUID has been proposed and developed. A normal pick-up coil was applied to detect the tangential magnetic field to the panel surface. Since the detected field could be related to the currents of the solar panels, the electric properties of the solar panels could be evaluated. In this work, the evaluation of the electric properties of the commercial solar panels as well as the electric circuits made by the discrete devices on the circuit board was visualized

Scalar hairy black holes and solitons in asymptotically flat spacetimes

International Nuclear Information System (INIS)

Nucamendi, Ulises; Salgado, Marcelo

2003-01-01

A numerical analysis shows that the Einstein field equations allow static and spherically symmetric black hole solutions with scalar-field hair in asymptotically flat spacetimes. When regularity at the origin is imposed (i.e., in the absence of a horizon) globally regular scalar solitons are found. The asymptotically flat solutions are obtained provided that the scalar potential V(φ) of the theory is not positive semidefinite and such that its local minimum is also a zero of the potential, the scalar field settling asymptotically at that minimum. The configurations, although unstable under spherically symmetric linear perturbations, are regular and thus can serve as counterexamples to the no-scalar-hair conjecture

Concept of a selective tumour therapy and its evaluation by near-infrared fluorescence imaging and flat-panel volume computed tomography in mice.

Science.gov (United States)

Alves, Frauke; Dullin, Christian; Napp, Joanna; Missbach-Guentner, Jeannine; Jannasch, Katharina; Mathejczyk, Julia; Pardo, Luis A; Stühmer, Walter; Tietze, Lutz-F

2009-05-01

Conventional chemotherapy of cancer has its limitations, especially in advanced and disseminated disease and suffers from lack of specificity. This results in a poor therapeutic index and considerable toxicity to normal organs. Therefore, many efforts are made to develop novel therapeutic tools against cancer with the aim of selectively targeting the drug to the tumour site. Drug delivery strategies fundamentally rely on the identification of good-quality biomarkers, allowing unequivocal discrimination between cancer and healthy tissue. At present, antibodies or antibody fragments have clearly proven their value as carrier molecules specific for a tumour-associated molecular marker. This present review draws attention to the use of near-infrared fluorescence (NIRF) imaging to investigate binding specificity and kinetics of carrier molecules such as monoclonal antibodies. In addition, flat-panel volume computed tomography (fpVCT) will be presented to monitor anatomical structures in tumour mouse models over time in a non-invasive manner. Each imaging device sheds light on a different aspect; functional imaging is applied to optimise the dose schedule and the concept of selective tumour therapies, whereas anatomical imaging assesses preclinically the efficacy of novel tumour therapies. Both imaging techniques in combination allow the visualisation of functional information obtained by NIRF imaging within an adequate anatomic framework.

Analysis of 3-panel and 4-panel microscale ionization sources

International Nuclear Information System (INIS)

Natarajan, Srividya; Parker, Charles B.; Glass, Jeffrey T.; Piascik, Jeffrey R.; Gilchrist, Kristin H.; Stoner, Brian R.

2010-01-01

Two designs of a microscale electron ionization (EI) source are analyzed herein: a 3-panel design and a 4-panel design. Devices were fabricated using microelectromechanical systems technology. Field emission from carbon nanotube provided the electrons for the EI source. Ion currents were measured for helium, nitrogen, and xenon at pressures ranging from 10 -4 to 0.1 Torr. A comparison of the performance of both designs is presented. The 4-panel microion source showed a 10x improvement in performance compared to the 3-panel device. An analysis of the various factors affecting the performance of the microion sources is also presented. SIMION, an electron and ion optics software, was coupled with experimental measurements to analyze the ion current results. The electron current contributing to ionization and the ion collection efficiency are believed to be the primary factors responsible for the higher efficiency of the 4-panel microion source. Other improvements in device design that could lead to higher ion source efficiency in the future are also discussed. These microscale ion sources are expected to find application as stand alone ion sources as well as in miniature mass spectrometers.

Panel 3 Studies in Childhood, Chuldren's Culture and Play Culture

DEFF Research Database (Denmark)

Toft, Herdis

A presentation of the collected Works of Flemming Mouritsen as published in "Mouritsen's Metode'. Herdis Toft as Panel Chair introduces the publication and also the panel of 6 researchers discussing his influence in the field.......A presentation of the collected Works of Flemming Mouritsen as published in "Mouritsen's Metode'. Herdis Toft as Panel Chair introduces the publication and also the panel of 6 researchers discussing his influence in the field....

Demonstration of a large-size horizontal light-field display based on the LED panel and the micro-pinhole unit array

Science.gov (United States)

Yang, Le; Sang, Xinzhu; Yu, Xunbo; Liu, Boyang; Liu, Li; Yang, Shenwu; Yan, Binbin; Du, Jingyan; Gao, Chao

2018-05-01

A 54-inch horizontal-parallax only light-field display based on the light-emitting diode (LED) panel and the micro-pinhole unit array (MPUA) is demonstrated. Normally, the perceived 3D effect of the three-dimensional (3D) display with smooth motion parallax and abundant light-field information can be enhanced with increasing the density of viewpoints. However, the density of viewpoints is inversely proportional to the spatial display resolution for the conventional integral imaging. Here, a special MPUA is designed and fabricated, and the displayed 3D scene constructed by the proposed horizontal light-field display is presented. Compared with the conventional integral imaging, both the density of horizontal viewpoints and the spatial display resolution are significantly improved. In the experiment, A 54-inch horizontal light-field display with 42.8° viewing angle based on the LED panel with the resolution of 1280 × 720 and the MPUA is realized, which can provide natural 3D visual effect to observers with high quality.

FLAT FEET OF DHE CHILDREN IN PRE-SCHOOL AGE

Directory of Open Access Journals (Sweden)

Admira Koničanin

2011-03-01

Full Text Available Subjekt : Of this research are flat feet of the children of both sexes in pre-school age children Aim : Of the research is confirm wheter is exists or flat feel of the children of both sexes in pre-school age.

Development of electromagnetic welding facility of flat plates for nuclear industry

Science.gov (United States)

Kumar, Rajesh; Sahoo, Subhanarayan; Sarkar, Biswanath; Shyam, Anurag

2017-04-01

Electromagnetic pulse welding (EMPW) process, one of high speed welding process uses electromagnetic force from discharged current through working coil, which develops a repulsive force between the induced current flowing parallel and in opposite direction. For achieving the successful weldment using this process the design of working coil is the most important factor due to high magnetic field on surface of work piece. In case of high quality flat plate welding factors such as impact velocity, angle of impact standoff distance, thickness of flyer and overlap length have to be chosen carefully. EMPW has wide applications in nuclear industry, automotive industry, aerospace, electrical industries. However formability and weldability still remain major issues. Due to ease in controlling the magnetic field enveloped inside tubes, the EMPW has been widely used for tube welding. In case of flat components control of magnetic field is difficult. Hence the application of EMPW gets restricted. The present work attempts to make a novel contribution by investigating the effect of process parameters on welding quality of flat plates. The work emphasizes the approaches and engineering calculations required to effectively use of actuator in EMPW of flat components.

A high-resolution full-field range imaging system

Science.gov (United States)

Carnegie, D. A.; Cree, M. J.; Dorrington, A. A.

2005-08-01

There exist a number of applications where the range to all objects in a field of view needs to be obtained. Specific examples include obstacle avoidance for autonomous mobile robots, process automation in assembly factories, surface profiling for shape analysis, and surveying. Ranging systems can be typically characterized as being either laser scanning systems where a laser point is sequentially scanned over a scene or a full-field acquisition where the range to every point in the image is simultaneously obtained. The former offers advantages in terms of range resolution, while the latter tend to be faster and involve no moving parts. We present a system for determining the range to any object within a camera's field of view, at the speed of a full-field system and the range resolution of some point laser scans. Initial results obtained have a centimeter range resolution for a 10 second acquisition time. Modifications to the existing system are discussed that should provide faster results with submillimeter resolution.

Benthic microalgae community response to flooding in a tropical salt flat

Directory of Open Access Journals (Sweden)

L. S. M. Masuda

Full Text Available Abstract This research evaluated the effect of flooding on the microphytobenthos community structure in a microbial mat from a tropical salt flat. Field samples were collected during four consecutive days: on the first three days the salt flat was dry, on the fourth day it was flooded by rain. In order to evaluate the community maintained in flood conditions, samples from this area were collected and kept in the laboratory for 10 days with sea water. The results of total abundance of microphytobenthos varied from 4.2 × 108 to 2.9 × 109 organisms L–1, total density increased one order of magnitude under the effect of water for both situations of precipitation in the salt flat and in experimental conditions, an increase due to the high abundance of Microcoleus spp. Shannon index (H’ was higher during the desiccation period. Our data suggest that changes in the abundance of organisms were due to the effect of water. The dominance of the most abundant taxa remained the same under conditions of desiccation and influence of water, and there is probably a consortium of microorganisms in the microbial mat that helps to maintain these dominances.

Field emission properties of ZnO nanosheet arrays

International Nuclear Information System (INIS)

Naik, Kusha Kumar; Rout, Chandra Sekhar; Khare, Ruchita; More, Mahendra A.; Chakravarty, Disha; Late, Dattatray J.; Thapa, Ranjit

2014-01-01

Electron emission properties of electrodeposited ZnO nanosheet arrays grown on Indium tin oxide coated glass substrates have been studied. Influence of oxygen vacancies on electronic structures and field emission properties of ZnO nanosheets are investigated using density functional theory. The oxygen vacancies produce unshared d electrons which form an impurity energy state; this causes shifting of Fermi level towards the vacuum, and so the barrier energy for electron extraction reduces. The ZnO nanosheet arrays exhibit a low turn-on field of 2.4 V/μm at 0.1 μA/cm 2 and current density of 50.1 μA/cm 2 at an applied field of 6.4 V/μm with field enhancement factor, β = 5812 and good field emission current stability. The nanosheet arrays grown by a facile electrodeposition process have great potential as robust high performance vertical structure electron emitters for future flat panel displays and vacuum electronic device applications

Fast brazing development for the joining of the beryllium armor layer for the ITER First Wall panels

International Nuclear Information System (INIS)

Buodot, C.; Boireau, B.; Lorenzetto, P.; Macel, D.

2006-01-01

In order to reduce cost and manufacturing time induction brazing is being developed as an alternative to Hot Isostatic Pressing for the joining of the beryllium armor onto the copper alloy heat sink material for the manufacture of First Wall panels for the ITER Blanket. The copper alloy that is currently adopted by ITER is a Copper Chromium Zirconium alloy. Its good mechanical properties are obtained by precipitation hardening by means of an ageing heat treatment at a temperature of about 480 o C. In order to avoid over-ageing and keep acceptable mechanical properties, brazing at higher temperatures must therefore be done as fast as possible. The flat geometry of a panel is not familiar for induction process; nevertheless, a development work was done validating the feasibility of joining beryllium tiles onto a copper chromium zirconium flat surface of a panel by induction brazing process. The development was done in 2 stages: validation of the capability of the induction process to realise a heat cycle on a dummy panel and in parallel, validation of the brazing parameters giving acceptable mechanical results on the beryllium CuCrZr joint. A flat pancake inductor was manufactured and tested on a dummy panel in an induction brazing vessel manufactured for this purpose. Several heating cycles were done with the aim of defining a cycle that gives uniform temperature at the interface of all the beryllium tiles on the entire panel surface. These cycles gave us a temperature range in which the brazing can be performed. A special device for brazing small mock up was also manufactured. This was for the metallurgical characterisation program. Many brazing samples where done and mechanically characterised. Unfortunately, this first metallurgical stage led to unacceptably low shear test values. A complete analysis of this non conformance put in evidence that the bad results were due to the braze material that was not adapted to this process. By changing the braze material

Compact muon solenoid magnet reaches full field

CERN Multimedia

2006-01-01

Scientist of the U.S. Department of Energy in Fermilab and collaborators of the US/CMS project announced that the world's largest superconducting solenoid magnet has reached full field in tests at CERN. (1 apge)

Manufacturing and Structural Feasibility of Natural Fiber Reinforced Polymeric Structural Insulated Panels for Panelized Construction

Directory of Open Access Journals (Sweden)

Nasim Uddin

2011-01-01

Full Text Available Natural fibers are emerging in the fields of automobile and aerospace industries to replace the parts such as body panels, seats, and other parts subjected to higher bending strength. In the construction industries, they have the potential to replace the wood and oriented strand boards (OSB laminates in the structural insulated panels (SIPs. They possess numerous advantages over traditional OSB SIPs such as being environmental friendly, recyclable, energy efficient, inherently flood resistant, and having higher strength and wind resistance. This paper mainly focuses on the manufacturing feasibility and structural characterization of natural fiber reinforced structural insulated panels (NSIPs using natural fiber reinforced polymeric (NFRP laminates as skin. To account for the use of natural fibers, the pretreatments are required on natural fibers prior to use in NFRP laminates, and, to address this issue properly, the natural fibers were given bleaching pretreatments. To this end, flexure test and low-velocity impact (LVI tests were carried out on NSIPs in order to evaluate the response of NSIPs under sudden impact loading and uniform bending conditions typical of residential construction. The paper also includes a comparison of mechanical properties of NSIPs with OSB SIPs and G/PP SIPs. The results showed significant increase in the mechanical properties of resulting NSIP panels mainly a 53% increase in load-carrying capacity compared to OSB SIPs. The bending modulus of NSIPs is 190% higher than OSB SIPs and 70% weight reduction compared to OSB SIPs.

Unitarity in three-dimensional flat space higher spin theories

International Nuclear Information System (INIS)

Grumiller, D.; Riegler, M.; Rosseel, J.

2014-01-01

We investigate generic flat-space higher spin theories in three dimensions and find a no-go result, given certain assumptions that we spell out. Namely, it is only possible to have at most two out of the following three properties: unitarity, flat space, non-trivial higher spin states. Interestingly, unitarity provides an (algebra-dependent) upper bound on the central charge, like c=42 for the Galilean W_4"("2"−"1"−"1") algebra. We extend this no-go result to rule out unitary “multi-graviton” theories in flat space. We also provide an example circumventing the no-go result: Vasiliev-type flat space higher spin theory based on hs(1) can be unitary and simultaneously allow for non-trivial higher-spin states in the dual field theory.

Stationary solutions and asymptotic flatness I

International Nuclear Information System (INIS)

Reiris, Martin

2014-01-01

In general relativity, a stationary isolated system is defined as an asymptotically flat (AF) stationary spacetime with compact material sources. Other definitions that are less restrictive on the type of asymptotic could in principle be possible. Between this article and its sequel, we show that under basic assumptions, asymptotic flatness indeed follows as a consequence of Einstein's theory. In particular, it is proved that any vacuum stationary spacetime-end whose (quotient) manifold is diffeomorphic to R 3 minus a ball and whose Killing field has its norm bounded away from zero, is necessarily AF with Schwarzschildian fall off. The ‘excised’ ball would contain (if any) the actual material body, but this information is unnecessary to reach the conclusion. In this first article, we work with weakly asymptotically flat (WAF) stationary ends, a notion that generalizes as much as possible that of the AF end, and prove that WAF ends are AF with Schwarzschildian fall off. Physical and mathematical implications are also discussed. (paper)

INDUCTION HEATING OF NON-MAGNETIC SHEET METALS IN THE FIELD OF A FLAT CIRCULAR MULTITURN SOLENOID

Directory of Open Access Journals (Sweden)

Y. Batygin

2016-06-01

Full Text Available The theoretical analysis of electromagnetic processes in the system for induction heating presented by a flat circular multiturn solenoid positioned above a plane of thin sheet non-magnetic metal has been conducted. The calculated dependences for the current induced in a metal sheet blank and ratio of transformation determined have been obtained. The maximal value of the transformation ratio with regard to spreading the eddy-currents over the whole area of the sheet metal has been determined.

Flat beams in a 50 TeV hadron collider

International Nuclear Information System (INIS)

Peggs, S.; Harrison, M.; Pilat, F.; Syphers, M.

1997-01-01

The basic beam dynamics of a next generation 50 x 50 TeV hadron collider based on a high field magnet approach have been outlined over the past several years. Radiation damping not only produces small emittances, but also flat beams, just as in electron machines. Based on open-quotes Snowmass 96close quotes parameters, we investigate the issues associated with flat beams in very high energy hadron colliders

Flat-field response and geometric distortion measurements of optical streak cameras

International Nuclear Information System (INIS)

Montgomery, D.S.; Drake, R.P.; Jones, B.A.; Wiedwald, J.D.

1987-01-01

To accurately measure pulse amplitude, shape, and relative time histories of optical signals with an optical streak camera, it is necessary to correct each recorded image for spatially-dependent gain nonuniformity and geometric distortion. Gain nonuniformities arise from sensitivity variations in the streak-tube photocathode, phosphor screen, image-intensifier tube, and image recording system. By using a 1.053-μm, long-pulse, high-power laser to generate a spatially and temporally uniform source as input to the streak camera, the combined effects of flat-field response and geometric distortion can be measured under the normal dynamic operation of cameras with S-1 photocathodes. Additionally, by using the same laser system to generate a train of short pulses that can be spatially modulated at the input of the streak camera, the authors can create a two-dimensional grid of equally-spaced pulses. This allows a dynamic measurement of the geometric distortion of the streak camera. The author discusses the techniques involved in performing these calibrations, present some of the measured results for LLNL optical streak cameras, and will discuss software methods to correct for these effects

Discussion panel: field test design & data analysis

Science.gov (United States)

Daniel M. Schmitt; William E. Waters; B. Leo Cadogan; Gerald S. Walton

1985-01-01

I think it is time to open the panel. On my left respectively are Bill Waters, Professor of Entomology and Forestry, University of California, Berkeley; Gerald S. Walton, Biometrician, Northeastern Forest Experiment Station, Hamden; and Leo Cadogan, Forest Pest Management Institute, Canadian Forestry Service, Sault Ste. Marie, Ontario. My name is Dan Schmitt, Program...

Dual-frequency ring-magnet power supply with flat bottom

International Nuclear Information System (INIS)

Praeg, W.F.

1983-01-01

A power supply is described that furnishes an essentially flat-bottom injection field, followed by a dual-frequency cosine field. This results in efficient beam capture during injection and reduces significantly the peak rf power required during acceleration in a rapid-cycling synchrotron

Design of a photovoltaic central power station: flat-plate array

Energy Technology Data Exchange (ETDEWEB)

1984-02-01

A design for a photovoltaic central power station using fixed flat-panel arrays has been developed. The 100 MW plant is assumed to be located adjacent to the Saguaro Power Station of Arizona Public Service. The design assumes high-efficiency photovoltaic modules using dendritic web cells. The modules are arranged in 5 MW subfields, each with its own power conditioning unit. The photovoltaic output is connected to the existing 115 kV utility switchyard. The site specific design allows detailed cost estimates for engineering, site preparation, and installation. Collector and power conditioning costs have been treated parametrically.

Puncture panel optimization

International Nuclear Information System (INIS)

Glass, R.E.; Longenbaugh, R.S.

1986-01-01

Sandia National Laboratories developed the TRansUranic PACkage Transporter (TRUPACT) to transport defense contact-handled transuranic wastes. The package has been designed to meet the normal and hypothetical accident conditions in 10CFR71 which includes the demonstrated ability to survive a 1-meter drop onto a mild steel pin. The puncture protection is provided by puncture resistant panels. In conjunction with the development of TRUPACT, a series of experiments has been conducted to reduce the weight of the puncture resistant panels. The initial scoping tests resulted in a preliminary design incorporating 30 layers of Kevlar. This design has been shown to meet the regulatory puncture test. To reduce the weight of this panel, subscale tests were conducted on panels utilizing Kevlar yarns with varying mass per unit length (denier) as well as different resins. This paper reviews the testing undertaken in the original panel development and discusses the results obtained from the recent subscale and full-scale optimization tests

Higher-spin algebras, holography and flat space

Energy Technology Data Exchange (ETDEWEB)

Sleight, C. [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, D-80805 Munich (Germany); Université Libre de Bruxelles and International Solvay Institutes,ULB-Campus Plaine CP231, 1050 Brussels (Belgium); Taronna, M. [Université Libre de Bruxelles and International Solvay Institutes,ULB-Campus Plaine CP231, 1050 Brussels (Belgium)

2017-02-20

In this article we study the higher-spin algebra behind the type-A cubic couplings recently extracted from the free O(N) model in generic dimensions, demonstrating that they coincide with the known structure constants for the unique higher-spin algebra in generic dimensions. This provides an explicit check of the holographic reconstruction and of the duality between higher-spin theories and the free O(N) model in generic dimensions, generalising the result of Giombi and Yin in AdS{sub 4}. For completeness, we also address the same problem in the flat space for the cubic couplings derived by Metsaev in 1991, which are recovered from the flat limit of the AdS type-A cubic couplings. We observe that both flat and AdS{sub 4} higher-spin Lorentz subalgebras coincide, hinting towards the existence of a full higher-spin symmetry behind the flat-space cubic couplings of Metsaev.

New edge-centered photonic square lattices with flat bands

Science.gov (United States)

Zhang, Da; Zhang, Yiqi; Zhong, Hua; Li, Changbiao; Zhang, Zhaoyang; Zhang, Yanpeng; Belić, Milivoj R.

2017-07-01

We report a new class of edge-centered photonic square lattices with multiple flat bands, and consider in detail two examples: the Lieb-5 and Lieb-7 lattices. In these lattices, there are 5 and 7 sites in the unit cell and in general, the number is restricted to odd integers. The number of flat bands m in the new Lieb lattices is related to the number of sites N in the unit cell by a simple formula m =(N - 1) / 2. The flat bands reported here are independent of the pseudomagnetic field. The properties of lattices with even and odd number of flat bands are different. We consider the localization of light in such Lieb lattices. If the input beam excites the flat-band mode, it will not diffract during propagation, owing to the strong mode localization. In the Lieb-7 lattice, the beam will also oscillate during propagation and still not diffract. The period of oscillation is determined by the energy difference between the two flat bands. This study provides a new platform for investigating light trapping, photonic topological insulators, and pseudospin-mediated vortex generation.

Quantitative comparison using Generalized Relative Object Detectability (G-ROD) metrics of an amorphous selenium detector with high resolution Microangiographic Fluoroscopes (MAF) and standard flat panel detectors (FPD).

Science.gov (United States)

Russ, M; Shankar, A; Jain, A; Setlur Nagesh, S V; Ionita, C N; Scott, C; Karim, K S; Bednarek, D R; Rudin, S

2016-02-27

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25 μ m pixel pitch, and 1000 μ m thick a-Se layer operating at 10V/ μ m bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-prewhitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal-spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide breakthrough abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

49 CFR 845.22 - Technical panel.

Science.gov (United States)

2010-10-01

... 49 Transportation 7 2010-10-01 2010-10-01 false Technical panel. 845.22 Section 845.22... Technical panel. The Director, Bureau of Accident Investigation, or the Director, Bureau of Field Operations, shall designate members of the Board's technical staff to participate in the hearing and initially...

Flat-panel detector volumetric CT for visualization of subarachnoid hemorrhage and ventricles: preliminary results compared to conventional CT

International Nuclear Information System (INIS)

Doelken, M.; Struffert, T.; Richter, G.; Engelhorn, T.; Doerfler, A.; Nimsky, C.; Ganslandt, O.; Hammen, T.

2008-01-01

The aim of this study was to compare flat-panel volumetric CT (VCT) to conventional CT (cCT) in the visualization of the extent of subarachnoid hemorrhage (SAH) and the width of the ventricles in patients with acute SAH. Included in the study were 22 patients with an acutely ruptured cerebral aneurysm who received VCT during coil embolization. VCT image quality, the extent of SAH (using a modified Fisher score and total slice number with SAH visible) and the width of the ventricles (Evans index) were evaluated by two experienced neuroradiologists (RAD1 and RAD2) and compared to the findings on cCT. Ten patients undergoing VCT for reasons other than SAH served as negative controls. Interobserver agreement in rating image quality was excellent for cCT (Kendall W value 0.94) and good for VCT (0.74). SAH was identified by RAD1 and RAD2 on VCT images in all patients. The modified Fisher scores underestimated the extent of SAH on VCT images in comparison with cCT images. Pearson's correlation coefficient (r) regarding the number of image slices with SAH visible on cCT images compared with the number on VCT images was 0.85 for RAD1 and 0.84 for RAD2. The r value for the degree of interobserver agreement for the number of slices with SAH visible was 0.99 for cCT, and 0.95 for VCT images (n 19), respectively. The width of the ventricles measured in terms of the Evans Index showed excellent concordance between the modalities (r = 0.81 vs. 0.82). Our preliminary results indicate that VCT is helpful in evaluating SAH in the angiography suite. Additionally, reliable evaluation of ventricle width is feasible. However, there are limitations with regard to the visibility of SAH on VCT images in comparison to cCT images. (orig.)

A study of the structural-acoustic response and interior noise levels of fuselage structures

Science.gov (United States)

Koval, L. R.

1978-01-01

Models of both flat and curved fuselage panels were tested for their sound transmission characteristics. The effect of external air flow on transmission loss was simulated in a subsonic wind-tunnel. By numerically evaluating the known equations for field-incidence transmission loss of single-walled panels in a computer program, a comparison of the theory with the test results was made. As a further extension to aircraft fuselage simulation, equations for the field-incidence transmission loss of a double-walled panel were derived. Flow is shown to provide a small increase in transmission loss for a flat panel. Curvature is shown to increase transmission loss for low frequencies, while also providing a sharp decrease in transmission loss at the ring frequency of the cylindrical panel. The field-incidence transmission loss of a double-walled panel was found to be approximately twice that for a single-walled panel, with the addition of dips in the transmission loss at the air gap resonances and at the critical frequency of the internal panel.

Stringy stability of charged dilaton black holes with flat event horizon

Energy Technology Data Exchange (ETDEWEB)

Ong, Yen Chin [National Taiwan Univ., Taipei (Taiwan); Chen, Pisin [National Taiwan Univ., Taipei (Taiwan); SLAC National Accelerator Lab., Menlo Park, CA (United States)

2015-01-15

Electrically charged black holes with flat event horizon in anti-de Sitter space have received much attention due to various applications in Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence, from modeling the behavior of quark-gluon plasma to superconductor. Critical to the physics on the dual field theory is the fact that when embedded in string theory, black holes in the bulk may become vulnerable to instability caused by brane pair-production. Since dilation arises naturally in the context of string theory, we study the effect of coupling dilation to Maxwell field on the stability of flat charged AdS black holes.

Impact behavior of basalt/epoxy composite: Comparison between flat and twill fabric

Science.gov (United States)

Papa, I.; Ricciardi, M. R.; Antonucci, V.; Langella, A.; Lopresto, V.

2018-05-01

Two types of basalt fibre reinforced epoxy laminates were realized by overlapping flat and twill woven basalt fabrics by resin infusion. Rectangular specimens, cut from the panels were impacted at penetration and at increasing energy values, to investigate the damage onset and propagation. A non-destructive technique, Ultrasound testing (UT), was adopted to investigate the internal damage. Despite the difficulties to obtain information by UT method due to the high amount of signal absorbed, the technique, properly calibrated, proved to be very useful in providing information about the presence, the shape and the extent of the delaminations. The results were compared at the aim to investigate the effect of the fiber architecture (textile). The experimental results indicate a similar impact behavior between basalt flat and twill composites but in the case of the twill a minor delaminated area was detected, even if a higher absorbed energy was recorded

Design and construction of a photobioreactor for hydrogen production, including status in the field.

Science.gov (United States)

Skjånes, Kari; Andersen, Uno; Heidorn, Thorsten; Borgvang, Stig A

Several species of microalgae and phototrophic bacteria are able to produce hydrogen under certain conditions. A range of different photobioreactor systems have been used by different research groups for lab-scale hydrogen production experiments, and some few attempts have been made to upscale the hydrogen production process. Even though a photobioreactor system for hydrogen production does require special construction properties (e.g., hydrogen tight, mixing by other means than bubbling with air), only very few attempts have been made to design photobioreactors specifically for the purpose of hydrogen production. We have constructed a flat panel photobioreactor system that can be used in two modes: either for the cultivation of phototrophic microorganisms (upright and bubbling) or for the production of hydrogen or other anaerobic products (mixing by "rocking motion"). Special emphasis has been taken to avoid any hydrogen leakages, both by means of constructional and material choices. The flat plate photobioreactor system is controlled by a custom-built control system that can log and control temperature, pH, and optical density and additionally log the amount of produced gas and dissolved oxygen concentration. This paper summarizes the status in the field of photobioreactors for hydrogen production and describes in detail the design and construction of a purpose-built flat panel photobioreactor system, optimized for hydrogen production in terms of structural functionality, durability, performance, and selection of materials. The motivations for the choices made during the design process and advantages/disadvantages of previous designs are discussed.

Development of hard X-ray dark-field microscope using full-field optics

International Nuclear Information System (INIS)

Takano, Hidekazu; Azuma, Hiroaki; Shimomura, Sho; Tsuji, Takuya; Tsusaka, Yoshiyuki; Kagoshima, Yasushi

2016-01-01

We develop a dark-field X-ray microscope using full-field optics based on a synchrotron beamline. Our setup consists of a condenser system and a microscope objective with an angular acceptance larger than that of the condenser. The condenser system is moved downstream from its regular position such that the focus of the condenser is behind the objective. The dark-field microscope optics are configured by excluding the converging beam from the condenser at the focal point. The image properties of the system are evaluated by observing and calculating a Siemens star test chart with 10 keV X-rays. Our setup allows easy switching to bright-field imaging. (author)

Flat magnetic exchange springs as mechanism for additional magnetoresistance in magnetic nanoisland arrays

Energy Technology Data Exchange (ETDEWEB)

Boltaev, A.P.; Pudonin, F.A. [P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Leninskiy Prospekt 53, 119991 Moscow (Russian Federation); Sherstnev, I.A., E-mail: sherstnev@lebedev.ru [P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Leninskiy Prospekt 53, 119991 Moscow (Russian Federation); Egorov, D.A. [National Research Nuclear University MEPhI, Kashirskoe shosse 31, 115409 Moscow (Russian Federation); Kozmin, A.M. [National Research University of Electronic Technology, Shokin Square, 1, Zelenograd, 124482 Moscow (Russian Federation)

2017-04-15

Process of magnetization and magnetoresistance have been studied in nanoisland bilayer systems of FeNi-Co. Hysteresis loops show characteristic features (steps) most clearly observed in certain orientations of the sample in a magnetic field. To explain these features the concept of flat magnetic exchange spring has been introduced for nanoisland bilayers. It has been proposed that additional magnetoresistance can be the result of spin-dependent scattering of electrons in the area of flat magnetic exchange spring. Magnetoresistance studies of bilayer systems has shown that additional magnetoresistance occurs at the same magnetic fields as steps on hysteresis loops. - Highlights: • Metallic FeNi-Co bilayers are studied. • FeNi and Co layers magnetize independently. • Concept of flat spin spring is proposed. • Additional magnetoresistance occurs in intermediate magnetic fields.

Flat magnetic exchange springs as mechanism for additional magnetoresistance in magnetic nanoisland arrays

International Nuclear Information System (INIS)

Boltaev, A.P.; Pudonin, F.A.; Sherstnev, I.A.; Egorov, D.A.; Kozmin, A.M.

2017-01-01

Process of magnetization and magnetoresistance have been studied in nanoisland bilayer systems of FeNi-Co. Hysteresis loops show characteristic features (steps) most clearly observed in certain orientations of the sample in a magnetic field. To explain these features the concept of flat magnetic exchange spring has been introduced for nanoisland bilayers. It has been proposed that additional magnetoresistance can be the result of spin-dependent scattering of electrons in the area of flat magnetic exchange spring. Magnetoresistance studies of bilayer systems has shown that additional magnetoresistance occurs at the same magnetic fields as steps on hysteresis loops. - Highlights: • Metallic FeNi-Co bilayers are studied. • FeNi and Co layers magnetize independently. • Concept of flat spin spring is proposed. • Additional magnetoresistance occurs in intermediate magnetic fields.

Derotation of the cosmic microwave background polarization: Full-sky formalism

International Nuclear Information System (INIS)

Gluscevic, Vera; Kamionkowski, Marc; Cooray, Asantha

2009-01-01

Mechanisms have been proposed that might rotate the linear polarization of the cosmic microwave background (CMB) as it propagates from the surface of last scatter. In the simplest scenario, the rotation will be uniform across the sky, but the rotation angle may also vary across the sky. We develop in detail the complete set of full-sky quadratic estimators for the rotation of the CMB polarization that can be constructed from the CMB temperature and polarization. We derive the variance with which these estimators can be measured and show that these variances reduce to the simpler flat-sky expressions in the appropriate limit. We evaluate the variances numerically. While the flat-sky formalism may be suitable if the rotation angle arises as a realization of a random field, the full-sky formalism will be required to search for rotations that vary slowly across the sky as well as for models in which the angular power spectrum for the rotation angle peaks at large angles.

Development of electromagnetic welding facility of flat plates for nuclear industry

International Nuclear Information System (INIS)

Kumar, Rajesh; Sahoo, Subhanarayan; Sarkar, Biswanath; Shyam, Anurag

2015-01-01

Electromagnetic pulse welding (EMPW) process, one of high speed welding process uses electromagnetic force from discharged current through working coil, which develops a repulsive force between the induced current flowing parallel and in opposite direction. For achieving the successful weldment using this process the design of working coil is the most important factor due to high magnetic field on surface of work piece. In case of high quality flat plate welding factors such as impact velocity, angle of impact standoff distance, thickness of flyer and overlap length have to be chosen carefully. All the parameters should be optimized because above or below the optimized value, it is impossible to get high quality welding of flat components. Electromagnetic pulse welding of flat components has been studied in detail by many researches due to its advantages of increased formability and reduced spring back than other welding methods. The feasibility of electromagnetic welding of sheets has been established, but the effect of process parameters on the weld quality has not been justified properly. The present study investigates the effect of parameters on welding quality of flat sheets, which has wide applications in nuclear industry, automotive industry, aerospace, electrical industries. However formability and weld ability still remain major issues. The EMPW process for flat sheets and axi-symmetric components has been studied in details by many researchers. Due to ease in controlling the magnetic field enveloped inside tubes, the EMPW has been widely used for tube welding. In case of flat components control of magnetic field is difficult. Hence the application of EMPW gets restricted. The present work attempts to make a novel contribution by investigating the effect of process parameters on welding quality. The work emphasizes the approaches and engineering calculations required to effectively use of actuator in EMPW. (author)

75 FR 12981 - Eligibility for Commercial Flats Failing Deflection

Science.gov (United States)

2010-03-18

... applicable only to automation flats, for all commercial flat-size mail except saturation and high-density...[supreg] pricing. If automation prices are denied, pieces that are prepared to be part of full-service IMb... compliance, but at additional cost; and quarter-folding would not work well with any inserts. Also, there was...

Detecting delaminations and disbondings on full-scale wing composite panel by guided waves based SHM system

Science.gov (United States)

Monaco, E.; Boffa, N. D.; Memmolo, V.; Ricci, F.; Maio, L.

2016-04-01

A full-scale lower wing panel made of composite material has been designed, manufactured and sensorised within the European Funded research project named SARISTU. The authors contributed to the whole development of the system, from design to implementation as well as to the impacts campaign phase where Barely Visible and Visible Damages (BVID and VID) are to be artificially induced on the panel by a pneumatic impact machine. This work summarise part of the experimental results related to damages production, their assessment by C-SCAN as reference NDT method as well as damage detection of delimitations by a guided waves based SHM. The SHM system is made by customized piezoelectric patches secondary bonded on the wing plate acting both as guided waves sources and receivers. The paper will deal mostly with the experimental impact campaign and the signal analyses carried out to extract the metrics more sensitive to damages induced. Image reconstruction of the damages dimensions and shapes will be also described based mostly on the combination of metrics maps over the plate partial surfaces. Finally a comparison of damages maps obtained by the SHM approach and those obtained by "classic" C-SCAN will be presented analyzing briefly pros and cons of the two different approached as a combination to the most effective structural maintenance scenario of a commercial aircraft.

Does Preinterventional Flat-Panel Computer Tomography Pooled Blood Volume Mapping Predict Final Infarct Volume After Mechanical Thrombectomy in Acute Cerebral Artery Occlusion?

International Nuclear Information System (INIS)

Wagner, Marlies; Kyriakou, Yiannis; Mesnil de Rochemont, Richard du; Singer, Oliver C.; Berkefeld, Joachim

2013-01-01

PurposeDecreased cerebral blood volume is known to be a predictor for final infarct volume in acute cerebral artery occlusion. To evaluate the predictability of final infarct volume in patients with acute occlusion of the middle cerebral artery (MCA) or the distal internal carotid artery (ICA) and successful endovascular recanalization, pooled blood volume (PBV) was measured using flat-panel detector computed tomography (FPD CT).Materials and MethodsTwenty patients with acute unilateral occlusion of the MCA or distal ACI without demarcated infarction, as proven by CT at admission, and successful Thrombolysis in cerebral infarction score (TICI 2b or 3) endovascular thrombectomy were included. Cerebral PBV maps were acquired from each patient immediately before endovascular thrombectomy. Twenty-four hours after recanalization, each patient underwent multislice CT to visualize final infarct volume. Extent of the areas of decreased PBV was compared with the final infarct volume proven by follow-up CT the next day.ResultsIn 15 of 20 patients, areas of distinct PBV decrease corresponded to final infarct volume. In 5 patients, areas of decreased PBV overestimated final extension of ischemia probably due to inappropriate timing of data acquisition and misery perfusion.ConclusionPBV mapping using FPD CT is a promising tool to predict areas of irrecoverable brain parenchyma in acute thromboembolic stroke. Further validation is necessary before routine use for decision making for interventional thrombectomy

Full-field x-ray nano-imaging at SSRF

Science.gov (United States)

Deng, Biao; Ren, Yuqi; Wang, Yudan; Du, Guohao; Xie, Honglan; Xiao, Tiqiao

2013-09-01

Full field X-ray nano-imaging focusing on material science is under developing at SSRF. A dedicated full field X-ray nano-imaging beamline based on bending magnet will be built in the SSRF phase-II project. The beamline aims at the 3D imaging of the nano-scale inner structures. The photon energy range is of 5-14keV. The design goals with the field of view (FOV) of 20μm and a spatial resolution of 20nm are proposed at 8 keV, taking a Fresnel zone plate (FZP) with outermost zone width of 25 nm. Futhermore, an X-ray nano-imaging microscope is under developing at the SSRF BL13W beamline, in which a larger FOV will be emphasized. This microscope is based on a beam shaper and a zone plate using both absorption contrast and Zernike phase contrast, with the optimized energy set to 10keV. The detailed design and the progress of the project will be introduced.

WE-AB-BRB-10: Filmless QA of CyberKnife MLC-Collimated and Iris-Collimated Fields

International Nuclear Information System (INIS)

Gersh, J

2015-01-01

Purpose: Current methods of CK field shape QA is based on the use of radiochromic film. Though accurate results can be attained, these methods are prone to error, time consuming, and expensive. The techniques described herein perform similar QA using the FOIL Detector (Field, Output, and Image Localization). A key feature of this in-house QA solution, and central to this study, is an aSi flat-panel detector which provides the user with the means to perform accurate, immediate, and quantitative field analysis. Methods: The FOIL detector is automatically aligned in the CK beam using fiducial markers implanted within the detector case. Once the system is aligned, a treatment plan is delivered which irradiates the flat-panel imager using the field being tested. The current study tests each of the clinically-used fields shaped using the Iris variable-aperture collimation system using a plan which takes 6 minutes to deliver. The user is immediately provided with field diameter and beam profile, as well as a comparison to baseline values. Additionally, the detector is used to acquire and analyze leaf positions of the InCise multi-leaf collimation system. Results: Using a 6-minute plan consisting of 11 beams of 25MU-per-beam, the FOIL detector provided the user with a quantitative analysis of all clinically-used field shapes. The FOIL detector was also able to clearly resolve field edge junctions in a picket fence test, including slight over-travel of individual leaves as well as inter-leaf leakage. Conclusion: The FOIL system provided comparable field diameter and profile data when compared to methods using film; providing results much faster and with 5% of the MU used for film. When used with the MLC system, the FOIL detector provided the means for immediate quantification of the performance of the system through analysis of leaf positions in a picket fence test field. Author is the President/Owner of Spectrum Medical Physics, LLC, a company which maintains contracts

WE-AB-BRB-10: Filmless QA of CyberKnife MLC-Collimated and Iris-Collimated Fields

Energy Technology Data Exchange (ETDEWEB)

Gersh, J [Gibbs Cancer Center and Research Institute - Pelham, Greer, SC (United States); Spectrum Medical Physics, LLC, Greenville, SC (United States)

2015-06-15

Purpose: Current methods of CK field shape QA is based on the use of radiochromic film. Though accurate results can be attained, these methods are prone to error, time consuming, and expensive. The techniques described herein perform similar QA using the FOIL Detector (Field, Output, and Image Localization). A key feature of this in-house QA solution, and central to this study, is an aSi flat-panel detector which provides the user with the means to perform accurate, immediate, and quantitative field analysis. Methods: The FOIL detector is automatically aligned in the CK beam using fiducial markers implanted within the detector case. Once the system is aligned, a treatment plan is delivered which irradiates the flat-panel imager using the field being tested. The current study tests each of the clinically-used fields shaped using the Iris variable-aperture collimation system using a plan which takes 6 minutes to deliver. The user is immediately provided with field diameter and beam profile, as well as a comparison to baseline values. Additionally, the detector is used to acquire and analyze leaf positions of the InCise multi-leaf collimation system. Results: Using a 6-minute plan consisting of 11 beams of 25MU-per-beam, the FOIL detector provided the user with a quantitative analysis of all clinically-used field shapes. The FOIL detector was also able to clearly resolve field edge junctions in a picket fence test, including slight over-travel of individual leaves as well as inter-leaf leakage. Conclusion: The FOIL system provided comparable field diameter and profile data when compared to methods using film; providing results much faster and with 5% of the MU used for film. When used with the MLC system, the FOIL detector provided the means for immediate quantification of the performance of the system through analysis of leaf positions in a picket fence test field. Author is the President/Owner of Spectrum Medical Physics, LLC, a company which maintains contracts

Reactive barrier technologies for treatment of contaminated groundwater at Rocky Flats

International Nuclear Information System (INIS)

Marozas, D.C.; Bujewski, G.E.; Castaneda, N.

1997-01-01

The U.S. Department of Energy (DOE) Office of Science and Technology Subsurface Contaminants Focus Area is supporting the investigation of reactive barrier technologies to mitigate the risks associated with mixed organic/radioactive waste at several DOE sites. Groundwater from a small contaminated plume at the Rocky Flats Environmental Technology Site (RFETS) is being used to evaluate passive reactive material treatment. Permeable reactive barriers which intercept contaminants and destroy the VOC component while containing radionuclides are attractive for a number of reasons relating to public and regulatory acceptance. In situ treatment keeps contaminants away from the earth's surface, there is no above-ground treatment equipment that could expose workers and the public and operational costs are expected to be lower than currently used technologies. This paper will present results from preliminary site characterization and in-field small-scale column testing of reactive materials at RFETS. Successful demonstration is expected to lead to full-scale implementation of the technology at several DOE sites, including Rocky Flats

Measurement of joint kinematics using a conventional clinical single-perspective flat-panel radiography system

International Nuclear Information System (INIS)

Seslija, Petar; Teeter, Matthew G.; Yuan Xunhua; Naudie, Douglas D. R.; Bourne, Robert B.; MacDonald, Steven J.; Peters, Terry M.; Holdsworth, David W.

2012-01-01

Purpose: The ability to accurately measure joint kinematics is an important tool in studying both normal joint function and pathologies associated with injury and disease. The purpose of this study is to evaluate the efficacy, accuracy, precision, and clinical safety of measuring 3D joint motion using a conventional flat-panel radiography system prior to its application in an in vivo study. Methods: An automated, image-based tracking algorithm was implemented to measure the three-dimensional pose of a sparse object from a two-dimensional radiographic projection. The algorithm was tested to determine its efficiency and failure rate, defined as the number of image frames where automated tracking failed, or required user intervention. The accuracy and precision of measuring three-dimensional motion were assessed using a robotic controlled, tibiofemoral knee phantom programmed to mimic a subject with a total knee replacement performing a stair ascent activity. Accuracy was assessed by comparing the measurements of the single-plane radiographic tracking technique to those of an optical tracking system, and quantified by the measurement discrepancy between the two systems using the Bland–Altman technique. Precision was assessed through a series of repeated measurements of the tibiofemoral kinematics, and was quantified using the across-trial deviations of the repeated kinematic measurements. The safety of the imaging procedure was assessed by measuring the effective dose of ionizing radiation associated with the x-ray exposures, and analyzing its relative risk to a human subject. Results: The automated tracking algorithm displayed a failure rate of 2% and achieved an average computational throughput of 8 image frames/s. Mean differences between the radiographic and optical measurements for translations and rotations were less than 0.08 mm and 0.07° in-plane, and 0.24 mm and 0.6° out-of-plane. The repeatability of kinematics measurements performed using the

Atmospheric dispersion modeling at the Rocky Flats Plant. Progress report, December 1981-December 1985

International Nuclear Information System (INIS)

Hodgin, C.R.

1986-01-01

The Rocky Flats Plant applies atmospheric dispersion modeling as a tool for Emergency Response, Risk Assessment, and Regulatory Compliance. Extreme variations in terrain around the facility have necessitated the development of an advanced modeling approach. The Terrain-Responsive Atmospheric Code (TRAC) was developed to treat realistically the changing wind, stability, dispersion, and deposition patterns that are experienced in mountainous areas. The result is a detailed picture of dose and deposition patterns associated with postulated or actual releases. A unified approach was taken to modeling needs at Rocky Flats. This produces consistent dose projections for all applications. A Risk Assessment version of TRAC is now operational. A high-speed version of the code is being implemented for Emergency Response, and development of a regulatory version is under way. Public, scientific, and governmental acceptance of TRAC is critical to successful applications at the Rocky Flats Plant. A program of peer review and regulatory approval was initiated to provide a full outside evaluation of our techniques. Full field validation (tracer testing) is key to demonstrating reliability of the TRAC model. A validation study was planned for implementation beginning in early CY-1986. The necessary funding ($500,000) is being sought. Although the TRAC model development and approval program was developed for site-specific needs at the Rocky Flats Plant, potential exists for wider application within the Department of Energy (DOE). The TRAC model can be easily applied at other sites in complex terrain. A coordinated approach to model validation throughout the Albquerque Operations Office (AL) or DOE complexes could prove more cost effective than site-by-site evaluations. Finally, the model approval procedure developed jointly by Rocky Flats and the Environmental Protection Agency (EPA) is general and could be applied to other models or as the basis for a DOE-wide program

Installation package for concentrating solar collector panels

Science.gov (United States)

1978-01-01

The concentrating solar collector panels comprise a complete package array consisting of collector panels using modified Fresnel prismatic lenses for a 10 to 1 concentrating ratio, supporting framework, fluid manifolding and tracking drive system, and unassembled components for field erection.

RECIPANEL: RECYCLED PAPER PANELS

Directory of Open Access Journals (Sweden)

HERNÁN CAÑOLA

2012-01-01

Full Text Available En este artículo se estudia la fabricación y el comportamiento mecánico de paneles a base de papel reciclado. El objetivo principal del proyecto es producir un prototipo de panel que emplee elementos provenientes de residuos sólidos (papel periódico y de un material conglomerante (cemento Portland blanco. El panel debe ser económico, debe tener buenas propiedades mecánicas y debe tener dimensiones comerciales para su uso en muros tabiques y en cielos falsos en la industria de la construcción. El Recipanel es un panel no estructural a base de papel reciclado. El Recipanel cumple las normas colombianas en lo relativo a los paneles de uso no estructural y presenta además unas excelentes características mecánicas.

Geochemical evidence for waning magmatism and polycyclic volcanism at Crater Flat, Nevada

International Nuclear Information System (INIS)

Perry, F.V.; Crowe, B.M.

1992-01-01

This paper reports that petrologic and geochemical studies of basaltic rocks in the Yucca Mountain region are currently focused on understanding the evolution of volcanism in the Crater Flat volcanic field and the mechanisms of polycyclic volcanic field and the mechanisms of polycyclic volcanism at the Lathrop Wells volcanic center, the youngest center in the Crater Flat volcanic field. Geochemical and petrologic data indicate that the magma chambers which supplied the volcanic centers at Crater Flat became situated at greater crustal depths as the field evolved. Deep magma chambers may be related to a waning magma flux that was unable to sustain upper crustal magma conduits and chambers. Geochemical data from the Lathrop Wells volcanic center indicate that eruptive units identified from field and geomorphic relationships are geochemically distinct. The geochemical variations cannot be explained by fractional crystallization of a single magma batch, indicating that several magma batches were involved in the formation of the Lathrop Wells center. Considering the low magma flux in the Yucca Mountain region in the Quaternary, the probability of several magma batches erupting essentially simultaneously at Lathrop Wells is considered remote

Quantitative image quality evaluation of pixel-binning in a flat-panel detector for x-ray fluoroscopy

International Nuclear Information System (INIS)

Srinivas, Yogesh; Wilson, David L.

2004-01-01

X-ray fluoroscopy places stringent design requirements on new flat-panel (FP) detectors, requiring both low-noise electronics and high data transfer rates. Pixel-binning, wherein data from more that one detector pixel are collected simultaneously, not only lowers the data transfer rate but also increases x-ray counts and pixel signal-to-noise ratio (SNR). In this study, we quantitatively assessed image quality of image sequences from four acquisition methods; no-binning and three types of binning; in synthetic images using a clinically relevant task of detecting an extended guidewire in a four-alternative forced-choice paradigm. Binning methods were conventional data-line (D) and gate-line (G) binning, and a novel method in which alternate frames in an image sequence used D and G binning. Two detector orientations placed the data lines either parallel or perpendicular to the guide wire. At a low exposure of 0.6 μR (1.548x10 -10 C/kg) per frame, irrespective of detector orientation, D binning with its reduced electronic noise was significantly (p -10 C/kg) per frame, with data lines parallel to the guidewire, detection with D binning was significantly (p<0.1) better than G binning. However, with data lines perpendicular to the guidewire, G binning was significantly (p<0.1) better than D binning because the partial area effect was reduced. Alternate binning was the best binning method when results were averaged over both orientations, and it was as good as the best binning method at either orientation. In addition, at low and high exposures, alternate binning gave a temporally fused image with a smooth guidewire, an important image quality feature not assessed in a detection experiment. While at high exposure, detection with no binning was as good, or better, than the best binning method, it might be impractical at fluoroscopy imaging rates. A computational observer model based on signal detection theory successfully fit data and was used to predict effects of

Optical identifications of flat-spectrum radio sources

International Nuclear Information System (INIS)

Condon, J.J.; Condon, M.A.; Broderick, J.J.; Davis, M.M.

1983-01-01

A complete sample of radio sources with S> or =0.3 Jy at 1400 MHz, +24 0 0 , and low-frequency spectral indices α(408, 1400) or =+0.5 are usually in empty fields. The lower limits that can be assigned to the radio-optical spectral indices α/sub RO/ of these sources are significantly higher than the median α/sub RO/ of the sources with flat high-frequency spectra, so the optical characteristics of the two classes of radio source are intrinsically different. The radio and optical fluxes of flat-spectrum QSO's appear to be correlated, at least when averaged over 10 2 --10 3 yr

Developed Turbulence: From Full Simulations to Full Mode Reductions

NARCIS (Netherlands)

Grossmann, Siegfried; Lohse, Detlef; Reeh, Achim

1996-01-01

Developed Navier-Stokes turbulence is simulated with varying wave-vector mode reductions. The flatness and the skewness of the velocity derivative depend on the degree of mode reduction. They show a crossover towards the value of the full numerical simulation when the viscous subrange starts to be

Flat Files - JSNP | LSDB Archive [Life Science Database Archive metadata

Lifescience Database Archive (English)

Full Text Available switchLanguage; BLAST Search Image Search Home About Archive Update History Data ... Data file File name: jsnp_flat_files File URL: ftp://ftp.biosciencedbc.jp/archiv...his Database Database Description Download License Update History of This Database Site Policy | Contact Us Flat Files - JSNP | LSDB Archive ...

Full-Field Strain Mapping at a Ge/Si Heterostructure Interface

Directory of Open Access Journals (Sweden)

Buwen Cheng

2013-05-01

Full Text Available The misfit dislocations and strain fields at a Ge/Si heterostructure interface were investigated experimentally using a combination of high-resolution transmission electron microscopy and quantitative electron micrograph analysis methods. The type of misfit dislocation at the interface was determined to be 60° dislocation and 90° full-edge dislocation. The full-field strains at the Ge/Si heterostructure interface were mapped by using the geometric phase analysis (GPA and peak pairs analysis (PPA, respectively. The effect of the mask size on the GPA and PPA results was analyzed in detail. For comparison, the theoretical strain fields of the misfit dislocations were also calculated by the Peierls-Nabarro and Foreman dislocation models. The results showed that the optimal mask sizes in GPA and PPA were approximately three tenths and one-tenth of the reciprocal lattice vector, respectively. The Foreman dislocation model with an alterable factor a = 4 can best describe the strain field of the misfit dislocation at the Ge/Si heterostructure interface.

Out-of-autoclave manufacturing of a stiffened thermoplastic carbon fibre PEEK panel

Science.gov (United States)

Flanagan, M.; Goggins, J.; Doyle, A.; Weafer, B.; Ward, M.; Bizeul, M.; Canavan, R.; O'Bradaigh, C.; Doyle, K.; Harrison, N.

2017-10-01

Out-of-Autoclave manufacturing methods, specifically Automated Tape Placement (ATP) and induction welding, used in the fabrication of a stiffened thermoplastic demonstrator panel, are presented in this study. The demonstrator panel consists of two stiffeners induction welded to a flat skin, to form a typical load bearing aerospace sub-component. The skin of the panel is manufactured from uni-directional Carbon Fibre (CF) Polyetheretherkeytone (PEEK) using laser assisted Automated Tape Placement (ATP) and the stiffeners are press formed from woven CF-PEEK. The stiffeners are fusion bonded to the skin using a continuous induction welding process. A susceptor material is used at the interface to ensure the required heating is concentrated at the weldline. Microscopy was used to examine the manufactured coupons for defects. Destructive testing was carried out to evaluate the strength of the overall assembly. The work shows that assemblies manufactured using continuous induction welding and ATP are suitable for load bearing aerospace applications.

Mussel beds are biological power stations on intertidal flats

Science.gov (United States)

Engel, Friederike G.; Alegria, Javier; Andriana, Rosyta; Donadi, Serena; Gusmao, Joao B.; van Leeuwe, Maria A.; Matthiessen, Birte; Eriksson, Britas Klemens

2017-05-01

Intertidal flats are highly productive areas that support large numbers of invertebrates, fish, and birds. Benthic diatoms are essential for the function of tidal flats. They fuel the benthic food web by forming a thin photosynthesizing compartment in the top-layer of the sediment that stretches over the vast sediment flats during low tide. However, the abundance and function of the diatom film is not homogenously distributed. Recently, we have realized the importance of bivalve reefs for structuring intertidal ecosystems; by creating structures on the intertidal flats they provide habitat, reduce hydrodynamic stress and modify the surrounding sediment conditions, which promote the abundance of associated organisms. Accordingly, field studies show that high chlorophyll a concentration in the sediment co-vary with the presence of mussel beds. Here we present conclusive evidence by a manipulative experiment that mussels increase the local biomass of benthic microalgae; and relate this to increasing biomass of microalgae as well as productivity of the biofilm across a nearby mussel bed. Our results show that the ecosystem engineering properties of mussel beds transform them into hot spots for primary production on tidal flats, highlighting the importance of biological control of sedimentary systems.

Modelado y simulación de un panel fotovoltaico empleando técnicas de inteligencia artificial; Modeling and simulation of a photovoltaic panel using artificial intelligence techniques

Directory of Open Access Journals (Sweden)

Adalberto Ospino Castro

2015-04-01

Full Text Available El trabajo presenta la modelación del comportamiento energético y la determinación de los parámetros del circuito equivalente de un panel fotovoltaico con el empleo de técnicas de inteligencia artificial. Para tal efecto, se desarrolló en Matlab un algoritmo genético que permite obtener los parámetros físicos no brindados por los fabricantes para la implementación de funciones matemáticas que se homologuen al comportamiento dinámico de un panel solar. El algoritmo desarrollado en Matlab permite determinar, además, la eficiencia del algoritmo seguidor del punto de máxima potencia del inversor, el cual es un parámetro de no simple obtención o no determinado en condiciones de campo. Finalmente, el algoritmo se probó satisfactoriamente en un panel solar monocristalino de 50W obteniendo adecuados resultados en comparación con el modelo experimental para diferentes niveles de irradiación solar. Los resultados demuestran que el proceso desarrollado constituye una herramienta que puede ser aplicada a paneles fotovoltaicos en condiciones de campo. The paper presents the modeling of the energy behavior and determination of equivalent circuit parameters for a photovoltaic panel using artificial intelligence techniques. For this purpose, it was performed a genetic algorithm in Matlab, which calculates the physical parameters not provided by manufacturers to implement mathematical functions that approve the dynamic behavior of a solar panel. In addition, the algorithm can determine the efficiency of the maximum power point tracking algorithm of the inverter, which is a parameter of not simple obtaining or not determined under field conditions. Finally, the algorithm was successfully tested in a monocrystalline solar 50W panel with excellent results, compared to the experimental model for different levels of solar irradiation. The results demonstrate that the developed process is a tool that can be applied to photovoltaic panels under

On-Line Flatness Measurement in the Steelmaking Industry

Directory of Open Access Journals (Sweden)

Rubén Usamentiaga

2013-08-01

Full Text Available Shape is a key characteristic to determine the quality of outgoing flat-rolled products in the steel industry. It is greatly influenced by flatness, a feature to describe how the surface of a rolled product approaches a plane. Flatness is of the utmost importance in steelmaking, since it is used by most downstream processes and customers for the acceptance or rejection of rolled products. Flatness sensors compute flatness measurements based on comparing the length of several longitudinal fibers of the surface of the product under inspection. Two main different approaches are commonly used. On the one hand, most mechanical sensors measure the tensile stress across the width of the rolled product, while manufacturing and estimating the fiber lengths from this stress. On the other hand, optical sensors measure the length of the fibers by means of light patterns projected onto the product surface. In this paper, we review the techniques and the main sensors used in the steelmaking industry to measure and quantify flatness defects in steel plates, sheets and strips. Most of these techniques and sensors can be used in other industries involving rolling mills or continuous production lines, such as aluminum, copper and paper, to name a few. Encompassed in the special issue, State-of-the-Art Sensors Technology in Spain 2013, this paper also reviews the most important flatness sensors designed and developed for the steelmaking industry in Spain.

Testing flat plate photovoltaic modules for terrestrial environment

Science.gov (United States)

Hoffman, A. R.; Arnett, J. C.; Ross, R. G., Jr.

1979-01-01

New qualification tests have been developed for flat plate photovoltaic modules. Temperature cycling, cyclic pressure load, and humidity exposure are especially useful for detecting design and fabrication deficiencies. There is positive correlation between many of the observed field effects, such as power loss, and qualification test induced degradation. The status of research efforts for the development of test methodology for field-related problems is reviewed.

Light-cone AdS/CFT-adapted approach to AdS fields/currents, shadows, and conformal fields

Energy Technology Data Exchange (ETDEWEB)

Metsaev, R.R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute, Leninsky prospect 53, Moscow 119991 (Russian Federation)

2015-10-16

Light-cone gauge formulation of fields in AdS space and conformal field theory in flat space adapted for the study of AdS/CFT correspondence is developed. Arbitrary spin mixed-symmetry fields in AdS space and arbitrary spin mixed-symmetry currents, shadows, and conformal fields in flat space are considered on an equal footing. For the massless and massive fields in AdS and the conformal fields in flat space, simple light-cone gauge actions leading to decoupled equations of motion are found. For the currents and shadows, simple expressions for all 2-point functions are also found. We demonstrate that representation of conformal algebra generators on space of currents, shadows, and conformal fields can be built in terms of spin operators entering the light-cone gauge formulation of AdS fields. This considerably simplifies the study of AdS/CFT correspondence. Light-cone gauge actions for totally symmetric arbitrary spin long conformal fields in flat space are presented. We apply our approach to the study of totally antisymmetric (one-column) and mixed-symmetry (two-column) fields in AdS space and currents, shadows, and conformal fields in flat space.

Aging and characterization of PVC compound used as flat-panel of a low cost solar collector; Envelhecimento e caracterizacao de compostos de PVC usado em placas de coletores solares de baixo custo

Energy Technology Data Exchange (ETDEWEB)

Prado, Bruna R.; Pinto, Tatiana T.; Bartoli, Julio R. [Depto. de Tecnologia de Polimeros, Faculdade de Engenharia Quimica/Universidade Estadual de Campinas. FEQ/UNICAMP, SP (Brazil)], e-mail: bartoli@feq.unicamp.br; Fernandes, Elizabeth G. [Tezca P and D Celulas Solares (Brazil)

2011-07-01

Regardless the excellent amount of solar irradiation in Brazil, the development and production of solar water heating systems did not reach the low-income families yet. The relatively high cost of conventional solar water heaters is still the main reason to prevent it. The development of a low cost solar water heater (around US$ 200), easy technology, was the scope of previous work. All-plastic solar collector prototypes were developed using unplasticized Poly (vinyl chloride) ceiling panels and tubes, commodities from building engineering. Nevertheless, the main thermal and photo degradation mechanisms for PVC are well known; the unusual application of PVC as solar collector materials should need a specific investigation on environmental aging. This work presents a study on outdoor aging and characterization of PVC flat-plate absorber of solar collectors after 5 years on use. (author)

Coupled Thermo-Electro-Magneto-Elastic Response of Smart Stiffened Panels

Science.gov (United States)

Bednarcyk, Brett A.; Yarrington, Phillip W.

2009-01-01

This report documents the procedures developed for incorporating smart laminate and panel analysis capabilities within the HyperSizer aerospace structural sizing software package. HyperSizer analyzes stiffened panels composed of arbitrary composite laminates through stiffener homogenization, or "smearing " techniques. The result is an effective constitutive equation for the stiffened panel that is suitable for use in a full vehicle-scale finite element analysis via MSC/NASTRAN. The existing thermo-elastic capabilities of HyperSizer have herein been extended to include coupled thermo-electro-magneto-elastic analysis capabilities. This represents a significant step toward realization of design tools capable of guiding the development of the next generation of smart aerospace structures. Verification results are presented that compare the developed smart HyperSizer capability with an ABAQUS piezoelectric finite element solution for a facesheet-flange combination. These results show good agreement between HyperSizer and ABAQUS, but highlight a limitation of the HyperSizer formulation in that constant electric field components are assumed.

Detection of small pulmonary nodules on chest radiographs: efficacy of dual-energy subtraction technique using flat-panel detector chest radiography

International Nuclear Information System (INIS)

Oda, S.; Awai, K.; Funama, Y.; Utsunomiya, D.; Yanaga, Y.; Kawanaka, K.; Nakaura, T.; Hirai, T.; Murakami, R.; Nomori, H.; Yamashita, Y.

2010-01-01

Aim: To investigate the effect of a double-exposure dual-energy subtraction (DES) technique on the diagnostic performance of radiologists detecting small pulmonary nodules on flat-panel detector (FPD) chest radiographs. Materials and methods: Using FPD radiography 41 sets of chest radiographs were obtained from 26 patients with pulmonary nodules measuring ≤20 mm and from 15 normal participants. Each dataset included standard and corresponding DES images. There were six non-solid, 10 part-solid, and 10 solid nodules. The mean size of the 26 nodules was 15 ± 4.8 mm. Receiver operating characteristic (ROC) analysis was performed to compare the performance of the eight board-certified radiologists. Results: For the eight radiologists, the mean value of the area under the ROC curve (AUC) without and with DES images was 0.62 ± 0.05 and 0.68 ± 0.05, respectively; the difference was statistically significant (p = 0.02). For part-solid nodules, the difference of the mean AUC value was statistically significant (AUC = 0.61 ± 0.07 versus 0.69 ± 0.05; p < 0.01); for non-solid nodules it was not (AUC = 0.62 ± 0.1 versus 0.61 ± 0.09; p = 0.73), and for solid nodules it was not (AUC = 0.75 ± 0.1 versus 0.78 ± 0.08; p = 0.23). For nodules with overlapping bone shadows, the difference of the mean AUC value was statistically significant (p = 0.03), for nodules without overlapping, it was not (p = 0.26). Conclusion: Use of a double-exposure DES technique at FPD chest radiography significantly improved the diagnostic performance of radiologists to detect small pulmonary nodules.

Analysis of absorbed energy and efficiency of a solar flat plate collector

Directory of Open Access Journals (Sweden)

Anderson Miguel Lenz

2017-07-01

Full Text Available The highest percentage in home electricity demands in Brazil lies with the water heating systems, where the electric shower has a great contribution in consumption. The use of solar thermal panels is an alternative to minimize the strain on the electrical system by heating water. Current study evaluates a water heating system built with materials commonly used in home constructions. The tested collector is a 1 m² flat plate. Experiments were conducted at the State University of Western Paraná (UNIOESTE, campus Cascavel, Paraná State, Brazil. Temperature data were collected by PT100 sensors and solar radiation was measured with a pyranometer, coupled to a CR-1000 datalogger, with readings and collection every 5 minutes for 1 year. Data collection and analysis showed that the system presented monthly efficiency ranging between 33.7 and 53.54%, and energy absorbed between 30.79 and 75.29 kWh m-².month. Results show the system is a good option for use in residential or rural water heating due to decrease in the electric bill.

Scattering Effects of Solar Panels on Space Station Antenna Performance

Science.gov (United States)

Panneton, Robert J.; Ngo, John C.; Hwu, Shian U.; Johnson, Larry A.; Elmore, James D.; Lu, Ba P.; Kelley, James S.

1994-01-01

Characterizing the scattering properties of the solar array panels is important in predicting Space Station antenna performance. A series of far-field, near-field, and radar cross section (RCS) scattering measurements were performed at S-Band and Ku-Band microwave frequencies on Space Station solar array panels. Based on investigation of the measured scattering patterns, the solar array panels exhibit similar scattering properties to that of the same size aluminum or copper panel mockup. As a first order approximation, and for worse case interference simulation, the solar array panels may be modeled using perfect reflecting plates. Numerical results obtained using the Geometrical Theory of Diffraction (GTD) modeling technique are presented for Space Station antenna pattern degradation due to solar panel interference. The computational and experimental techniques presented in this paper are applicable for antennas mounted on other platforms such as ship, aircraft, satellite, and space or land vehicle.

Measurement of full-field deformation induced by a dc electrical field in organic insulator films

Directory of Open Access Journals (Sweden)

Boudou L.

2010-06-01

Full Text Available Digital image correlation method (DIC using the correlation coefficient curve-fitting for full-field surface deformation measurements of organic insulator films is investigated in this work. First the validation of the technique was undertaken. The computer-generated speckle images and the measurement of coefficient of thermal expansion (CTE of aluminium are used to evaluate the measurement accuracy of the technique. In a second part the technique is applied to measure the mechanical deformation induced by electrical field application to organic insulators. For that Poly(ethylene naphthalene 2,6-dicarboxylate (PEN thin films were subjected to DC voltage stress and DIC provides the full-field induced deformations of the test films. The obtained results show that the DIC is a practical and robust tool for better comprehension of mechanical behaviour of the organic insulator films under electrical stress.

Sub-crop geologic map of pre-Tertiary rocks in the Yucca Flat and northern Frenchman Flat areas, Nevada Test Site, southern Nevada

Energy Technology Data Exchange (ETDEWEB)

Cole, J.C.; Harris, A.G.; Wahl, R.R.

1997-10-02

This map displays interpreted structural and stratigraphic relations among the Paleozoic and older rocks of the Nevada Test Site region beneath the Miocene volcanic rocks and younger alluvium in the Yucca Flat and northern Frenchman Flat basins. These interpretations are based on a comprehensive examination and review of data for more than 77 drillholes that penetrated part of the pre-Tertiary basement beneath these post-middle Miocene structural basins. Biostratigraphic data from conodont fossils were newly obtained for 31 of these holes, and a thorough review of all prior microfossil paleontologic data is incorporated in the analysis. Subsurface relationships are interpreted in light of a revised regional geologic framework synthesized from detailed geologic mapping in the ranges surrounding Yucca Flat, from comprehensive stratigraphic studies in the region, and from additional detailed field studies on and around the Nevada Test Site. All available data indicate the subsurface geology of Yucca Flat is considerably more complicated than previous interpretations have suggested. The western part of the basin, in particular, is underlain by relics of the eastward-vergent Belted Range thrust system that are folded back toward the west and thrust by local, west-vergent contractional structures of the CP thrust system. Field evidence from the ranges surrounding the north end of Yucca Flat indicate that two significant strike-slip faults track southward beneath the post-middle Miocene basin fill, but their subsurface traces cannot be closely defined from the available evidence. In contrast, the eastern part of the Yucca Flat basin is interpreted to be underlain by a fairly simple north-trending, broad syncline in the pre-Tertiary units. Far fewer data are available for the northern Frenchman Flat basin, but regional analysis indicates the pre-Tertiary structure there should also be relatively simple and not affected by thrusting. This new interpretation has implications

Sub-crop geologic map of pre-Tertiary rocks in the Yucca Flat and northern Frenchman Flat areas, Nevada Test Site, southern Nevada

International Nuclear Information System (INIS)

Cole, J.C.; Harris, A.G.; Wahl, R.R.

1997-01-01

This map displays interpreted structural and stratigraphic relations among the Paleozoic and older rocks of the Nevada Test Site region beneath the Miocene volcanic rocks and younger alluvium in the Yucca Flat and northern Frenchman Flat basins. These interpretations are based on a comprehensive examination and review of data for more than 77 drillholes that penetrated part of the pre-Tertiary basement beneath these post-middle Miocene structural basins. Biostratigraphic data from conodont fossils were newly obtained for 31 of these holes, and a thorough review of all prior microfossil paleontologic data is incorporated in the analysis. Subsurface relationships are interpreted in light of a revised regional geologic framework synthesized from detailed geologic mapping in the ranges surrounding Yucca Flat, from comprehensive stratigraphic studies in the region, and from additional detailed field studies on and around the Nevada Test Site. All available data indicate the subsurface geology of Yucca Flat is considerably more complicated than previous interpretations have suggested. The western part of the basin, in particular, is underlain by relics of the eastward-vergent Belted Range thrust system that are folded back toward the west and thrust by local, west-vergent contractional structures of the CP thrust system. Field evidence from the ranges surrounding the north end of Yucca Flat indicate that two significant strike-slip faults track southward beneath the post-middle Miocene basin fill, but their subsurface traces cannot be closely defined from the available evidence. In contrast, the eastern part of the Yucca Flat basin is interpreted to be underlain by a fairly simple north-trending, broad syncline in the pre-Tertiary units. Far fewer data are available for the northern Frenchman Flat basin, but regional analysis indicates the pre-Tertiary structure there should also be relatively simple and not affected by thrusting. This new interpretation has implications

UPPER EXTREMITY KINEMATICS OF FLAT SERVE IN TENNIS ...

African Journals Online (AJOL)

Brian McAllister

kinematics on the ball velocity at the impact phase of a tennis flat serve. 15 elite male tennis players were recruited to participate in this study (mean age 18.4±3.3 .... For field calibration, a Direct Linear Transformation technique, developed by ...

Boundary dynamics of asymptotically flat 3D gravity coupled to higher spin fields

International Nuclear Information System (INIS)

González, Hernán A.; Pino, Miguel

2014-01-01

We construct a two-dimensional action principle invariant under a spin-three extension of BMS_3 group. Such a theory is obtained through a reduction of Chern-Simons action with a boundary. This procedure is carried out by imposing a set of boundary conditions obtained from asymptotically flat spacetimes in three dimensions. When implementing part of this set, we obtain an analog of chiral WZW model based on a contraction of sl(3,ℝ)×sl(3,ℝ). The remaining part of the boundary conditions imposes constraints on the conserved currents of the model, which allows to further reduce the action principle. It is shown that a sector of this latter theory is related to a flat limit of Toda theory

Boundary dynamics of asymptotically flat 3D gravity coupled to higher spin fields

Energy Technology Data Exchange (ETDEWEB)

González, Hernán A. [Physique Théorique et Mathématique,Université Libre de Bruxelles & International Solvay Institutes,Campus Plaine C.P. 231, B-1050 Bruxelles (Belgium); Pino, Miguel [Departamento de Física, Universidad de Santiago de Chile,Av. Ecuador 3493, Estación Central, Santiago (Chile)

2014-05-27

We construct a two-dimensional action principle invariant under a spin-three extension of BMS{sub 3} group. Such a theory is obtained through a reduction of Chern-Simons action with a boundary. This procedure is carried out by imposing a set of boundary conditions obtained from asymptotically flat spacetimes in three dimensions. When implementing part of this set, we obtain an analog of chiral WZW model based on a contraction of sl(3,ℝ)×sl(3,ℝ). The remaining part of the boundary conditions imposes constraints on the conserved currents of the model, which allows to further reduce the action principle. It is shown that a sector of this latter theory is related to a flat limit of Toda theory.

Flat Engineered Multichannel Reflectors

Directory of Open Access Journals (Sweden)

V. S. Asadchy

2017-09-01

Full Text Available Recent advances in engineered gradient metasurfaces have enabled unprecedented opportunities for light manipulation using optically thin sheets, such as anomalous refraction, reflection, or focusing of an incident beam. Here, we introduce a concept of multichannel functional metasurfaces, which are able to control incoming and outgoing waves in a number of propagation directions simultaneously. In particular, we reveal a possibility to engineer multichannel reflectors. Under the assumption of reciprocity and energy conservation, we find that there exist three basic functionalities of such reflectors: specular, anomalous, and retroreflections. Multichannel response of a general flat reflector can be described by a combination of these functionalities. To demonstrate the potential of the introduced concept, we design and experimentally test three different multichannel reflectors: three- and five-channel retroreflectors and a three-channel power splitter. Furthermore, by extending the concept to reflectors supporting higher-order Floquet harmonics, we forecast the emergence of other multichannel flat devices, such as isolating mirrors, complex splitters, and multi-functional gratings.

Rocky Flats Neutron Detector Testing at Valduc, France

International Nuclear Information System (INIS)

Kim, S.S.; Dulik, G.M.

2011-01-01

Recent program requirements of the US Department of Energy/NNSA have led to a need for a criticality accident alarm system to be installed at a newly activated facility. The Criticality Safety Group of the Lawrence Livermore National Laboratory (LLNL) was able to recover and store for possible future use approximately 200 neutron criticality detectors and 20 master alarm panels from the former Rocky Flats Plant in Golden, Colorado when the plant was closed. The Criticality Safety Group participated in a facility analysis and evaluation, the engineering design and review process, as well as the refurbishment, testing, and recalibration of the Rocky Flats criticality alarm system equipment to be used in the new facility. In order to demonstrate the functionality and survivability of the neutron detectors to the effects of an actual criticality accident, neutron detector testing was performed at the French CEA Valduc SILENE reactor from October 7 to October 19, 2010. The neutron detectors were exposed to three criticality events or pulses generated by the SILENE reactor. The first excursion was performed with a bare or unshielded reactor, and the second excursion was made with a lead shielded/reflected reactor, and the third excursion with a polyethylene reflected core. These tests of the Rocky Flats neutron detectors were performed as a part of the 2010 Criticality Accident Alarm System Benchmark Measurements at the SILENE Reactor. The principal investigators for this series of experiments were Thomas M. Miller and John C. Wagner of the Oak Ridge National Laboratory, with Nicolas Authier and Nathalie Baclet of CEA Valduc. Several other organizations were also represented, including the Y-12 National Security Complex, Lawrence Livermore National Laboratory, Los Alamos National Laboratory, CEA Saclay, and Babcock International Group.

Methods for determining the effect of flatness deviations, eccentricity and pyramidal errors on angle measurements

CSIR Research Space (South Africa)

Kruger, OA

2000-01-01

Full Text Available on face-to-face angle measurements. The results show that flatness and eccentricity deviations have less effect on angle measurements than do pyramidal errors. 1. Introduction Polygons and angle blocks are the most important transfer standards in the field... of angle metrology. Polygons are used by national metrology institutes (NMIs) as transfer standards to industry, where they are used in conjunction with autocollimators to calibrate index tables, rotary tables and other forms of angle- measuring equipment...

Panel cutting method: new approach to generate panels on a hull in Rankine source potential approximation

Directory of Open Access Journals (Sweden)

Hee-Jong Choi

2011-12-01

Full Text Available In the present study, a new hull panel generation algorithm, namely panel cutting method, was developed to predict flow phenomena around a ship using the Rankine source potential based panel method, where the iterative method was used to satisfy the nonlinear free surface condition and the trim and sinkage of the ship was taken into account. Numerical computations were performed to investigate the validity of the proposed hull panel generation algorithm for Series 60 (CB=0.60 hull and KRISO container ship (KCS, a container ship designed by Maritime and Ocean Engineering Research Institute (MOERI. The computational results were validated by comparing with the existing experimental data.

Energy and exergy analyses of Photovoltaic/Thermal flat transpired collectors: Experimental and theoretical study

International Nuclear Information System (INIS)

Gholampour, Maysam; Ameri, Mehran

2016-01-01

Highlights: • A Photovoltaic/Thermal flat transpired collector was theoretically and experimentally studied. • Performance of PV/Thermal flat transpired plate was evaluated using equivalent thermal, first, and second law efficiencies. • According to the actual exergy gain, a critical radiation level was defined and its effect was investigated. • As an appropriate tool, equivalent thermal efficiency was used to find optimum suction velocity and PV coverage percent. - Abstract: PV/Thermal flat transpired plate is a kind of air-based hybrid Photovoltaic/Thermal (PV/T) system concurrently producing both thermal and electrical energy. In order to develop a predictive model, validate, and investigate the PV/Thermal flat transpired plate capabilities, a prototype was fabricated and tested under outdoor conditions at Shahid Bahonar University of Kerman in Kerman, Iran. In order to develop a mathematical model, correlations for Nusselt numbers for PV panel and transpired plate were derived using CFD technique. Good agreement was obtained between measured and simulated values, with the maximum relative root mean square percent deviation (RMSE) being 9.13% and minimum correlation coefficient (R-squared) 0.92. Based on the critical radiation level defined in terms of the actual exergy gain, it was found that with proper fan and MPPT devices, there is no concern about the critical radiation level. To provide a guideline for designers, using equivalent thermal efficiency as an appropriate tool, optimum values for suction velocity and PV coverage percent under different conditions were obtained.

Lag and ghosting in a clinical flat-panel selenium digital mammography system

International Nuclear Information System (INIS)

Bloomquist, Aili K.; Yaffe, Martin J.; Mawdsley, Gordon E.; Hunter, David M.; Beideck, Daniel J.

2006-01-01

We present measurements of lag and ghosting in a FDA-approved digital mammography system that uses a dielectric/selenium based detector structure. Lag is the carryover of signal from a previous image, whereas ghosting is the reduction of sensitivity caused by previous exposure history of the detector. Data from six selenium units were acquired. For the type of selenium detector tested, and under typical clinical usage conditions, the lag was as high as 0.15% of source signal and the ghosting could be as high as 15%. The amount of lag and ghosting varied from unit to unit. Results were compared with data acquired on a phosphor-based full-field digital mammography system. Modifications in the technology of the selenium detectors appear to have resulted in a marked decrease in both lag and ghosting effects in more recent systems

Flat-topped emission centred at 1 250 nm from quantum dot superluminescent diodes

Directory of Open Access Journals (Sweden)

R.A. Hogg

2010-01-01

Full Text Available We present a method for tailoring a broadband and flat-topped emission spectrum in quantum dot superluminescent diodes based upon modification of the dots-in-compositionally-modulated-well (DCMWELL technique. We demonstrate flat-topped emission with 95 nm full width at half maximum (FWHM, centred at 1 250 nm, and with output power in excess of 8 mW.

Unitary evolution and uniqueness of the Fock quantization in flat cosmologies

International Nuclear Information System (INIS)

Marugán, G A Mena; Błas, D Martín-de; Gomar, L Castelló

2013-01-01

We study the Fock quantization of scalar fields with a time dependent mass in cosmological scenarios with flat compact spatial sections. This framework describes physically interesting situations like, e.g., cosmological perturbations in flat Friedmann-Robertson-Walker spacetimes, generally including a suitable scaling of them by a background function. We prove that the requirements of vacuum invariance under the spatial isometries and of a unitary quantum dynamics select (a) a unique canonical pair of field variables among all those related by time dependent canonical transformations which scale the field configurations, and (b) a unique Fock representation for the canonical commutation relations of this pair of variables. The proof is generalizable to any compact spatial topology in three or less dimensions, though we focus on the case of the three-torus owing to the especially relevant implications.

Stability of response characteristics of a Delphi panel: application of bootstrap data expansion

Directory of Open Access Journals (Sweden)

Cole Bryan R

2005-12-01

Full Text Available Abstract Background Delphi surveys with panels of experts in a particular area of interest have been widely utilized in the fields of clinical medicine, nursing practice, medical education and healthcare services. Despite this wide applicability of the Delphi methodology, there is no clear identification of what constitutes a sufficient number of Delphi survey participants to ensure stability of results. Methods The study analyzed the response characteristics from the first round of a Delphi survey conducted with 23 experts in healthcare quality and patient safety. The panel members had similar training and subject matter understanding of the Malcolm Baldrige Criteria for Performance Excellence in Healthcare. The raw data from the first round sampling, which usually contains the largest diversity of responses, were augmented via bootstrap sampling to obtain computer-generated results for two larger samples obtained by sampling with replacement. Response characteristics (mean, trimmed mean, standard deviation and 95% confidence intervals for 54 survey items were compared for the responses of the 23 actual study participants and two computer-generated samples of 1000 and 2000 resampling iterations. Results The results from this study indicate that the response characteristics of a small expert panel in a well-defined knowledge area are stable in light of augmented sampling. Conclusion Panels of similarly trained experts (who possess a general understanding in the field of interest provide effective and reliable utilization of a small sample from a limited number of experts in a field of study to develop reliable criteria that inform judgment and support effective decision-making.

Experimental study of the possibility of reducing the resistance and unevenness of output field of velocities in flat diffuser channels with large opening angles

Science.gov (United States)

Dmitriev, S. S.; Vasil'ev, K. E.; Mokhamed, S. M. S. O.; Gusev, A. A.; Barbashin, A. V.

2017-11-01

In modern combined cycle gas turbines (CCGT), when designing the reducers from the output diffuser of a gas turbine to a boiler-utilizer, wide-angle diffusers are used, in which practically from the input a flow separation and transition to jet stream regime occurs. In such channels, the energy loss in the field of velocities sharply rise and the field of velocities in the output from them is characterized by considerable unevenness that worsens the heat transfer process in the first by motion tube bundles of the boiler-utilizer. The results of experimental research of the method for reducing the energy loss and alignment of the field of velocities at the output from a flat asymmetrical diffuser channel with one deflecting wall with the opening angle of 40° by means of placing inside the channel the flat plate parallel to the deflecting wall are presented in the paper. It is revealed that, at this placement of the plate in the channel, it has a chance to reduce the energy loss by 20%, considerably align the output field of velocities, and decrease the dynamic loads on the walls in the output cross-section. The studied method of resistance reduction and alignment of the fields of velocities in the flat diffuser channels was used for optimization of the reducer from the output diffuser of the gas turbine to the boiler-utilizer of CCGT of PGU-450T type of Kaliningrad Thermal Power Plant-2. The obtained results are evidence that the configuration of the reducer installed in the PGU-450T of Kaliningrad Thermal Power Plant-2 is not optimal. It follows also from the obtained data that working-off the reducer should be necessarily conducted by the test results of the channel consisting of the model of reducer with the model of boiler-utilizer installed behind it. Application of the method of alignment of output field of velocities and reducing the resistance in the wide-angle diffusers investigated in the work made it possible—when using the known model of diffusion

Analysis and enhancement of multiactuator panels for wave field synthesis reproduction.

OpenAIRE

PUEO ORTEGA, BASILIO JAVIER

2011-01-01

Esta tesis aborda el desarrollo y mejora de los altavoces de panel multiexcitados (MAPs) con particular importancia en su aplicación para la reproducción de síntesis de campo (WFS). Los altavoces MAPs pueden usarse como alternativa a las agrupaciones de altavoces dinámicos para WFS con ventajas adicionales. Sin embargo, puesto que los altavoces MAPs son paneles finitos que se excitan en varios puntos de su superficie, existen cuestiones estructurales y geométricas que deben ser tratadas para ...

Flat-field response and geometric distortion measurements of optical streak cameras

International Nuclear Information System (INIS)

Montgomery, D.S.; Drake, R.P.; Jones, B.A.; Wiedwald, J.D.

1987-08-01

To accurately measure pulse amplitude, shape, and relative time histories of optical signals with an optical streak camera, it is necessary to correct each recorded image for spatially-dependent gain nonuniformity and geometric distortion. Gain nonuniformities arise from sensitivity variations in the streak-tube photocathode, phosphor screen, image-intensifier tube, and image recording system. These nonuniformities may be severe, and have been observed to be on the order of 100% for some LLNL optical streak cameras. Geometric distortion due to optical couplings, electron-optics, and sweep nonlinearity not only affects pulse position and timing measurements, but affects pulse amplitude and shape measurements as well. By using a 1.053-μm, long-pulse, high-power laser to generate a spatially and temporally uniform source as input to the streak camera, the combined effects of flat-field response and geometric distortion can be measured under the normal dynamic operation of cameras with S-1 photocathodes. Additionally, by using the same laser system to generate a train of short pulses that can be spatially modulated at the input of the streak camera, we can effectively create a two-dimensional grid of equally-spaced pulses. This allows a dynamic measurement of the geometric distortion of the streak camera. We will discuss the techniques involved in performing these calibrations, will present some of the measured results for LLNL optical streak cameras, and will discuss software methods to correct for these effects. 6 refs., 6 figs

Full-field measurements and identification in solid mechanics

CERN Document Server

Grediac, Michel

2008-01-01

This timely book presents cutting-edge developments by experts in the field on the rapidly developing and scientifically challenging area of full-field measurement techniques used in solid mechanics - including photoelasticity, grid methods, deflectometry, holography, speckle interferometry and digital image correlation. The evaluation of strains and the use of the measurements in subsequent parameter identification techniques to determine material properties are also presented. Since parametric identification techniques require a close coupling of theoretical models and experimental measurements, the book focuses on specific modeling approaches that include finite element model updating, the equilibrium gap method, constitutive equation gap method, virtual field method and reciprocity gap method. In the latter part of the book, the authors discuss two particular applications of selected methods that are of special interest to many investigators: the analysis of localized phenomenon and connections between mi...

A Coal Burst Mitigation Strategy for Tailgate during Deep Mining of Inclined Longwall Top Coal Caving Panels at Huafeng Coal Mine

Directory of Open Access Journals (Sweden)

Guorui Feng

2018-01-01

Full Text Available A coal burst mitigation strategy for tailgate in mining of deep inclined longwall panels with top coal caving at Huafeng Coal Mine is presented in this paper. Field data showed that coal bursts, rib sloughing or slabbing, large convergence, and so forth frequently occurred within the tailgate entries during development and panel retreating employing standard longwall top coal caving (LTCC layout which resulted in fatal injuries and tremendous profit loss. The contributing factors leading to coal bursts were analyzed. Laboratory tests, in situ measurement, and field observation demonstrate that the intrinsic bursting proneness of the coal seam and immediate roof stratum, deep cover, overlying ultrathick (500–800 m conglomerate strata, faults, and, most importantly, improper panel layout led to coal bursts. By employing a new strategy, that is, longwall mining with split-level gateroads (LMSG, gateroads on either end of a LMSG panel are located at different levels within a coal seam, adjacent LMSG panels overlap end to end, and the tailgate of the adjacent new LMSG panel can be located below the headgate entry of the previous LMSG panel or may be offset horizontally with respect to it. Numerical modeling was carried out to investigate the stress distribution and yield zone development within surrounding rock mass which was validated by field investigation. The results indicate that standard LTCC system gave rise to high ground pressure around tailgate entries next to the gob, while LMSG tailgate entry below the gob edge was in a destressed environment. Therefore, coal bursts are significantly mitigated. Field practice of LMSG at Huafeng Coal Mine demonstrates how the new strategy effectively dealt with coal burst problems in mining of deep inclined longwall panels with a reduced incidence of ground control problems. The new strategy can potentially be applied in similar settings.

Weyl-Euler-Lagrange Equations of Motion on Flat Manifold

Directory of Open Access Journals (Sweden)

Zeki Kasap

2015-01-01

Full Text Available This paper deals with Weyl-Euler-Lagrange equations of motion on flat manifold. It is well known that a Riemannian manifold is said to be flat if its curvature is everywhere zero. Furthermore, a flat manifold is one Euclidean space in terms of distances. Weyl introduced a metric with a conformal transformation for unified theory in 1918. Classical mechanics is one of the major subfields of mechanics. Also, one way of solving problems in classical mechanics occurs with the help of the Euler-Lagrange equations. In this study, partial differential equations have been obtained for movement of objects in space and solutions of these equations have been generated by using the symbolic Algebra software. Additionally, the improvements, obtained in this study, will be presented.

Creating flat design websites

CERN Document Server

Pratas, Antonio

2014-01-01

This book contains practical, step-by-step tutorials along with plenty of explanation about designing your flat website. Each section is introduced sequentially, building up your web design skills and completing your website.Creating Flat Design Websites is ideal for you if you are starting on your web development journey, but this book will also benefit seasoned developers wanting to start developing in flat.

40 CFR 230.42 - Mud flats.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Mud flats. 230.42 Section 230.42... Aquatic Sites § 230.42 Mud flats. (a) Mud flats are broad flat areas along the sea coast and in coastal rivers to the head of tidal influence and in inland lakes, ponds, and riverine systems. When mud flats...

Flat-port connectors

KAUST Repository

Alrashed, Mohammed

2017-05-26

Disclosed are various embodiments for connectors used with electronic devices, such as input and/or output ports to connect peripheral equipment or accessories. More specifically, various flat-port are provided that can be used in place of standard connectors including, but not limited to, audio jacks and Universal Serial Bus (USB) ports. The flat-port connectors are an alternate connection design to replace the traditional receptacle port (female-port), making the device more sealed creation more dust and water resistant. It is unique in the way of using the outer surfaces of the device for the electrical connection between the ports. Flat-port design can allow the manufacture of extremely thin devices by eliminating the side ports slots that take a lot of space and contribute to the increase thickness of the device. The flat-port receptacle improves the overall appearance of the device and makes it more resistant to dust and water.

Full-Field Indentation Damage Measurement Using Digital Image Correlation

Directory of Open Access Journals (Sweden)

Elías López-Alba

2017-07-01

Full Text Available A novel approach based on full-field indentation measurements to characterize and quantify the effect of contact in thin plates is presented. The proposed method has been employed to evaluate the indentation damage generated in the presence of bending deformation, resulting from the contact between a thin plate and a rigid sphere. For this purpose, the 3D Digital Image Correlation (3D-DIC technique has been adopted to quantify the out of plane displacements at the back face of the plate. Tests were conducted using aluminum thin plates and a rigid bearing sphere to evaluate the influence of the thickness and the material behavior during contact. Information provided by the 3D-DIC technique has been employed to perform an indirect measurement of the contact area during the loading and unloading path of the test. A symmetrical distribution in the contact damage region due to the symmetry of the indenter was always observed. In the case of aluminum plates, the presence of a high level of plasticity caused shearing deformation as the load increased. Results show the full-field contact damage area for different plates’ thicknesses at different loads. The contact damage region was bigger when the thickness of the specimen increased, and therefore, bending deformation was reduced. With the proposed approach, the elastic recovery at the contact location was quantified during the unloading, as well as the remaining permanent indentation damage after releasing the load. Results show the information obtained by full-field measurements at the contact location during the test, which implies a substantial improvement compared with pointwise techniques.

Development of Surfaces Optically Suitable for Flat Solar Panels. [using a reflectometer which separately evaluates spectral and diffuse reflectivities of surfaces

Science.gov (United States)

1979-01-01

A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces is described. A phase locked detection system for the reflectometer is also described. A selective coating on aluminum potentially useful for flat plate solar collector applications is presented. The coating is composed of strongly bound copper oxide (divalent) and is formed by an etching process performed on an aluminum alloy with high copper content. Fabrication costs are expected to be small due to the one stop fabrication process. A number of conclusions gathered from the literature as to the required optical properties of flat plate solar collectors are discussed.

Blackbody radiation from light cone in flat space time

International Nuclear Information System (INIS)

Gerlach, U.H.

1983-01-01

Blackbody radiation in flat space-time is not necessarily associated with the flat event horizon of a single accelerated observer. The author considers a spherical bubble which expands in a uniformly accelerating fashion. Its history traces out a time-like hyperboloid. Suppose the bubble membrane has a spatially isotropic and homogeneous (surface) stress energy tensor i.e. the membrane is made out of the stiffest possible material permitted by causality considerations. It follows that this bubble membrane is in equilibrium even though it is expanding. Such an expanding bubble membrane may serve as a detector of electromagnetic radiation if the membrane can interact with the electromagnetic field. (Auth.)

Prevalence of Flat Foot: Comparison between Male and Female Primary School Students

Directory of Open Access Journals (Sweden)

Reihaneh Askary Kachoosangy

2013-10-01

Full Text Available Objectives: The aim of this study was to determine the prevalence of flat foot in a population of 7-12 year old students and to investigate the relationship between flat foot and age and sex. Methods: In this cross-sectional study, a total of 945 students (460 girls and 485 boys were examined. The presence of flatfoot and the degree of its severity according to Tachdjian's system of grading for flatfoot was assessed. Results: The data showed that the overall prevalence of flat foot was 74% out of which 23% were mild, 34% were moderate and 17% were severe. The prevalence of flat foot in girl and boy students were 75.2% and 72.6% respectively, but this difference was not significant. Moreover, no significant relationship was observed between the prevalence of flat foot and age. Discussion: This study showed that flat foot is a common problem among primary school students and should be addressed by responsible organizations.

THE FLAT TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ1214b FROM WIDE FIELD CAMERA 3 ON THE HUBBLE SPACE TELESCOPE

International Nuclear Information System (INIS)

Berta, Zachory K.; Charbonneau, David; Désert, Jean-Michel; Irwin, Jonathan; Miller-Ricci Kempton, Eliza; Fortney, Jonathan J.; Nutzman, Philip; McCullough, Peter R.; Burke, Christopher J.; Homeier, Derek

2012-01-01

Capitalizing on the observational advantage offered by its tiny M dwarf host, we present Hubble Space Telescope/Wide Field Camera 3 (WFC3) grism measurements of the transmission spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, finding the transmission spectrum of GJ1214b to be flat between 1.1 and 1.7 μm. Inconsistent with a cloud-free solar composition atmosphere at 8.2σ, the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b's outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the flat transmission spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 μm in diameter.

Cosmological consequences of supersymmetric flat directions

CERN Document Server

Riva, Francesco; Sarkar, Subir; Giudice, Gian

In this work we analyze various implications of the presence of large field vacum expectation values (VEVs) along supersymmetric flat direct ions during the early universe. First, we discuss supersymmetric leptogenesis and the grav itino bound. Supersym- metric thermal leptogenesis with a hierarchical right-han ded neutrino mass spectrum normally requires the mass of the lightest right-handed neu trino to be heavier than about 10 9 GeV. This is in conflict with the upper bound on the reheating t empera- ture which is found by imposing that the gravitinos generate d during the reheating stage after inflation do not jeopardize successful nucleosy nthesis. We show that a solution to this tension is actually already incorporated i n the framework, because of the presence of flat directions in the supersymmetric scalar potential. Massive right- handed neutrinos are efficiently produced non-thermally and the observed baryon asymmetry can be explained even for a reheating temperature respecting the grav- itino bound...

The Development of the Flat-Knitted Shaped Uppers based on Ergonomics

Directory of Open Access Journals (Sweden)

Lu Zhiwen

2016-06-01

Full Text Available To achieve the efficiency and specification of the flat-knitted uppers design, the basic patterns of uppers are made from shoe lasts based on the research on the characteristics of human’s feet and wearability requirements on uppers. The knitting technology for half-shaped and fully shaped uppers was formed after the shear deformation of basic pattern and combination with flat knitting technology. As regards to the functional requirements on key parts of uppers, the structures of flat-knitted shaped uppers were intensively analysed and studied, dividing them into two categories (functional structure and decorative structure, discussing the knitting methods and advantages of different structure, and finally experimentally proving that the planar pattern of flat knitted uppers can apply to the design of flat-knitted uppers and achieve the combination of functionality and artistry of sneakers after combining with structural changes, with a great significance on the achievement of the efficient production of uppers and the enhancement of its commercial value.

Study on the optium operation of the solar assisted air-source heat pump system. Part 5. ; Fundamental performance of a SOL-AIR PANEL effected by environmental condition that can be controlled artifically. SOL-AIR heat pump system no saiteki untenho ni kansuru kenkyu. 5. ; Jinko kankyo joken hendo ni uoru shuhonetsu panel no kiso tokusei

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Y; Ohashi, K; Kasuya, A [Kogauin Univ., Tokyo (Japan); Shiraishi, K; Hino, T [Kajima Institute of Construction Technology, Tokyo (Japan)

1990-12-06

This paper follows the privious paper which reports about the experimental system of the solar air panel and the experimental conditions in the artificial environmental room. In this paper the basic performance of heat exchange of a solar panel related to the difference of the artificial enviromental conditions such as the wind speed, the wind direction, the radiation, and the dry or wet surface of the solar air panel, and the results of its analysis are presented. As a result of the experiment, the following were determined: wind direction affects the heat exchange characteristics of the solar air panel; the slits lead to improved heat conduction on both sides of the panel; and when the flat surface of the panel is wet the amount of all the heat exchange increases, due to increased air circulation and evaporation. It is possible to estimate the total quantity of heat exchange, and to determine the fundamental performance of a solar air panel. 7 refs., 10 figs.

Holographic interferometry for early diagnosisof children flat foot

Directory of Open Access Journals (Sweden)

Oleg Petrovich Bolshakov

2015-03-01

Full Text Available The article presents the first experience ofthe use of holographic interferometr y for earlydiagnosis of the flat foot in 4-5 years old children.13 patients were examined. The results of the clinicalexamination, plantography, and of the graphicalreconstruction of the form of the foot arch basedon the interferogramms of the prints on Pedilen areanalyzed. We revealed typical differences betweenthe form of the foot arches in children with flat foot and children with normal status. The use of the proposed method for early detection of congenital pes valgus and of the signs of “flexible flat” foot is being suggested.

Problematic of the integration of the solar panels in the cover of the buildings of houses; Problematica de la integracion de los paneles solares en la cubierta de los edificios de viviendas

Energy Technology Data Exchange (ETDEWEB)

Lopez, F.

2008-07-01

This report describes schematically the different possibilities to place the thermal solar panels in a block of flats (building) between party walls and the precautions for their maintenance, pointing out the need to solve the formal aspects related to the resolution of the technical-functional aspects of the whole installation. This requires an interdisciplinary work in which the different sectors implied (architects, engineers, industry and communication) will have to intervene, in a word to take part. (Author)

Holography in asymptotically flat spacetimes and the BMS group

International Nuclear Information System (INIS)

Arcioni, Giovanni; Dappiaggi, Claudio

2004-01-01

In a previous paper (Arcioni G and Dappiaggi C 2003 Preprint hep-th/0306142) we have started to explore the holographic principle in the case of asymptotically flat spacetimes and analysed, in particular, different aspects of the Bondi-Metzner-Sachs (BMS) group, namely the asymptotic symmetry group of any asymptotically flat spacetime. We continue this investigation in this paper. Having in mind an S-matrix approach with future and past null infinity playing the role of holographic screens on which the BMS group acts, we connect the IR sectors of the gravitational field with the representation theory of the BMS group. We analyse the (complicated) mapping between bulk and boundary symmetries pointing out differences with respect to the anti-de Sitter (AdS)/CFT set up. Finally, we construct a BMS phase space and a free Hamiltonian for fields transforming with respect to BMS representations. The last step is supposed to be an explorative investigation of the boundary data living on the degenerate null manifold at infinity

SU-E-I-53: Comparison of Kerma-Area-Product Between the Micro-Angiographic Fluoroscope (MAF) and a Flat Panel Detector (FPD) as Used in Neuro-Endovascular Procedures

International Nuclear Information System (INIS)

Vijayan, S; Rana, V; Nagesh, S Setlur; Xiong, Z; Rudin, S; Bednarek, D

2015-01-01

Purpose: To determine the reduction of integral dose to the patient when using the micro-angiographic fluoroscope (MAF) compared to when using the standard flat-panel detector (FPD) for the techniques used during neurointerventional procedures. Methods: The MAF is a small field-of-view, high resolution x-ray detector which captures 1024 x 1024 pixels with an effective pixel size of 35μm and is capable of real-time imaging up to 30 frames per second. The MAF was used in neuro-interventions during those parts of the procedure when high resolution was needed and the FPD was used otherwise. The technique parameters were recorded when each detector was used and the kerma-area-product (KAP) per image frame was determined. KAP values were calculated for seven neuro interventions using premeasured calibration files of output as a function of kVp and beam filtration and included the attenuation of the patient table for the frontal projections to be more representative of integral patient dose. The air kerma at the patient entrance was multiplied by the beam area at that point to obtain the KAP values. The ranges of KAP values per frame were determined for the range of technique parameters used during the clinical procedures. To appreciate the benefit of the higher MAF resolution in the region of interventional activity, DA technique parameters were generally used with the MAF. Results: The lowest and highest values of KAP per frame for the MAF in DA mode were 4 and 50 times lower, respectively, compared to those of the FPD in pulsed fluoroscopy mode. Conclusion: The MAF was used in those parts of the clinical procedures when high resolution and image quality was essential. The integral patient dose as represented by the KAP value was substantially lower when using the MAF than when using the FPD due to the much smaller volume of tissue irradiated. This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873

SU-E-I-53: Comparison of Kerma-Area-Product Between the Micro-Angiographic Fluoroscope (MAF) and a Flat Panel Detector (FPD) as Used in Neuro-Endovascular Procedures

Energy Technology Data Exchange (ETDEWEB)

Vijayan, S; Rana, V; Nagesh, S Setlur; Xiong, Z; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)

2015-06-15

Purpose: To determine the reduction of integral dose to the patient when using the micro-angiographic fluoroscope (MAF) compared to when using the standard flat-panel detector (FPD) for the techniques used during neurointerventional procedures. Methods: The MAF is a small field-of-view, high resolution x-ray detector which captures 1024 x 1024 pixels with an effective pixel size of 35μm and is capable of real-time imaging up to 30 frames per second. The MAF was used in neuro-interventions during those parts of the procedure when high resolution was needed and the FPD was used otherwise. The technique parameters were recorded when each detector was used and the kerma-area-product (KAP) per image frame was determined. KAP values were calculated for seven neuro interventions using premeasured calibration files of output as a function of kVp and beam filtration and included the attenuation of the patient table for the frontal projections to be more representative of integral patient dose. The air kerma at the patient entrance was multiplied by the beam area at that point to obtain the KAP values. The ranges of KAP values per frame were determined for the range of technique parameters used during the clinical procedures. To appreciate the benefit of the higher MAF resolution in the region of interventional activity, DA technique parameters were generally used with the MAF. Results: The lowest and highest values of KAP per frame for the MAF in DA mode were 4 and 50 times lower, respectively, compared to those of the FPD in pulsed fluoroscopy mode. Conclusion: The MAF was used in those parts of the clinical procedures when high resolution and image quality was essential. The integral patient dose as represented by the KAP value was substantially lower when using the MAF than when using the FPD due to the much smaller volume of tissue irradiated. This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873.

"Flat-Fish" Vacuum Chamber

CERN Multimedia

CERN PhotoLab

1978-01-01

The picture shows a "Flat-Fish" vacuum chamber being prepared in the ISR workshop for testing prior to installation in the Split Field Magnet (SFM) at intersection I4. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of thin stainless steel sheets to the Split Field Magnet poles in order to take the vertical component of the atmospheric pressure force. This was the thinnest vacuum chamber ever made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature. In this picture the thin sheets transferring the vertical component of the atmosferic pressure force are attached to a support frame for testing. See also 7712182, 7712179.

Flat-Panel Cone-Beam Ct-Guided Radiofrequency Ablation of Very Small (≤1.5 cm) Liver Tumors: Technical Note on a Preliminary Experience

Energy Technology Data Exchange (ETDEWEB)

Cazzato, Roberto Luigi, E-mail: r.cazzato@unicampus.it; Buy, Xavier, E-mail: x.buy@bordeaux.unicancer.fr; Alberti, Nicolas, E-mail: nicoalbertibdx@gmail.com; Fonck, Mariane, E-mail: m.fonk@bordeaux.unicancer.fr [Institut Bergonié 229 Cours de l’Argonne, Department of Radiology (France); Grasso, Rosario Francesco, E-mail: r.grasso@unicampus.it [Università “Campus Bio-Medico di Roma”, Department of Radiology and Diagnostic Imaging (Italy); Palussière, Jean, E-mail: j.palussiere@bordeaux.unicancer.fr [Institut Bergonié 229 Cours de l’Argonne, Department of Radiology (France)

2015-02-15

PurposeThe aim of the present study was to investigate the technical feasibility of flat-panel cone-beam CT (CBCT)-guided radiofrequency ablation (RFA) of very small (<1.5 cm) liver tumors.Materials and MethodsPatients included were candidates for hepatic percutaneous RFA as they had single biopsy-proven hepatic tumors sized ≤1.5 cm and poorly defined on ultrasonography. Following apnea induction, unenhanced CBCT scans were acquired and used to deploy the RF electrode with the aid of a virtual navigation system. If the tumor was not clearly identified on the unenhanced CBCT scan, a right retrograde arterial femoral access was established to carry out hepatic angiography and localize the tumor. Patients’ lesions and procedural variables were recorded and analyzed.ResultsThree patients (2 male and 1 female), aged 68, 76, and 87 years were included; 3 lesions (2 hepato-cellular carcinoma and 1 metastasis from colorectal cancer) were treated. One patient required hepatic angiography. Cycles of apnea used to acquire CBCT images and to deploy the electrode lasted <120 s. Mean fluoroscopic time needed to deploy the electrode was 36.6 ± 5.7 min. Mean overall procedural time was 66.0 ± 22.9 min. No peri- or post-procedural complications were noted. No cases of incomplete ablation were noted at 1-month follow-up.ConclusionPercutaneous CBCT-guided liver RFA with or without arterial hepatic angiography is technically feasible.

Imaging responses of on-site CsI and Gd2O2S flat-panel detectors: Dependence on the tube voltage

Science.gov (United States)

Jeon, Hosang; Chung, Myung Jin; Youn, Seungman; Nam, Jiho; Lee, Jayoung; Park, Dahl; Kim, Wontaek; Ki, Yongkan; Kim, Ho Kyung

2015-07-01

One of the emerging issues in radiography is low-dose imaging to minimize patient's exposure. The scintillating materials employed in most indirect flat-panel detectors show a drastic change of X-ray photon absorption efficiency around their K-edge energies that consequently affects image quality. Using various tube voltages, we investigated the imaging performance of most popular scintillators: cesium iodide (CsI) and gadolinium oxysulfide (Gd2O2S). The integrated detective quantum efficiencies (iDQE) of four detectors installed in the same hospital were evaluated according to the standardized procedure IEC 62220-1 at tube voltages of 40 - 120 kVp. The iDQE values of the Gd2O2S detectors were normalized by those of CsI detectors to exclude the effects of image postprocessing. The contrast-to-noise ratios (CNR) were also evaluated by using an anthropomorphic chest phantom. The iDQE of the CsI detector outperformed that of the Gd2O2S detector over all tube voltages. Moreover, we noted that the iDQE of the Gd2O2S detectors quickly rolled off with decreasing tube voltage under 70 kVp. The CNRs of the two scintillators were similar at 120 kVp. At 60 kVp, however, the CNR of Gd2O2S was about half that of CsI. Compared to the Gd2O2S detectors, variations in the DQE performance of the CsI detectors were relatively immune to variations in the applied tube voltages. Therefore, we claim that Gd2O2S detectors are inappropriate for use in low-tube-voltage imaging (e.g., extremities and pediatrics) with low patient exposure.

Modification of parabolic dish antenna pattern using two symmetrically placed circular flat plates

Science.gov (United States)

Thorpe, Glen C.

1987-12-01

This study aims to formulate a method of predicting the far field pattern of a parabolic dish antenna with two moveable flat plates mounted symmetrically on either side of the feed horn. The approach taken has been to first analyze the radiation pattern of the antenna with the disks at certain heights out from the surface of the dish. To do this the near-field radiation in amplitude and phase was measured over a plane surface in the near-field and the values were then transformed into the far field using a Fast Fourier Transform. Far field pattern values of the antenna were directly measured for each setting of the plates. The results obtained from the Fast Fourier Transform of the near field data were in good agreement with the values obtained by measurement. Finally, an approximate model of the antenna was developed and implemented as a computer program. This model, while relatively unsophisticated, provided some insights into the changes in the near field phase distribution caused by the moveable circular flat plates.

Noise variance analysis using a flat panel x-ray detector: A method for additive noise assessment with application to breast CT applications

Energy Technology Data Exchange (ETDEWEB)

Yang Kai; Huang, Shih-Ying; Packard, Nathan J.; Boone, John M. [Department of Radiology, University of California, Davis Medical Center, 4860 Y Street, Suite 3100 Ellison Building, Sacramento, California 95817 (United States); Department of Radiology, University of California, Davis Medical Center, 4860 Y Street, Suite 3100 Ellison Building, Sacramento, California 95817 (United States) and Department of Biomedical Engineering, University of California, Davis, Davis, California, 95616 (United States)

2010-07-15

Purpose: A simplified linear model approach was proposed to accurately model the response of a flat panel detector used for breast CT (bCT). Methods: Individual detector pixel mean and variance were measured from bCT projection images acquired both in air and with a polyethylene cylinder, with the detector operating in both fixed low gain and dynamic gain mode. Once the coefficients of the linear model are determined, the fractional additive noise can be used as a quantitative metric to evaluate the system's efficiency in utilizing x-ray photons, including the performance of different gain modes of the detector. Results: Fractional additive noise increases as the object thickness increases or as the radiation dose to the detector decreases. For bCT scan techniques on the UC Davis prototype scanner (80 kVp, 500 views total, 30 frames/s), in the low gain mode, additive noise contributes 21% of the total pixel noise variance for a 10 cm object and 44% for a 17 cm object. With the dynamic gain mode, additive noise only represents approximately 2.6% of the total pixel noise variance for a 10 cm object and 7.3% for a 17 cm object. Conclusions: The existence of the signal-independent additive noise is the primary cause for a quadratic relationship between bCT noise variance and the inverse of radiation dose at the detector. With the knowledge of the additive noise contribution to experimentally acquired images, system modifications can be made to reduce the impact of additive noise and improve the quantum noise efficiency of the bCT system.

Flat slices in Minkowski space

Science.gov (United States)

Murchadha, Niall Ó.; Xie, Naqing

2015-03-01

Minkowski space, flat spacetime, with a distance measure in natural units of d{{s}2}=-d{{t}2}+d{{x}2}+d{{y}2}+d{{z}2}, or equivalently, with spacetime metric diag(-1, +1, +1, +1), is recognized as a fundamental arena for physics. The Poincaré group, the set of all rigid spacetime rotations and translations, is the symmetry group of Minkowski space. The action of this group preserves the form of the spacetime metric. Each t = constant slice of each preferred coordinate system is flat. We show that there are also nontrivial non-singular representations of Minkowski space with complete flat slices. If the embedding of the flat slices decays appropriately at infinity, the only flat slices are the standard ones. However, if we remove the decay condition, we find non-trivial flat slices with non-vanishing extrinsic curvature. We write out explicitly the coordinate transformation to a frame with such slices.

Flatness of two-dimensional beam profile measured with an ionization chamber array

International Nuclear Information System (INIS)

Stefanovski, Z.

2006-01-01

Open beam profiles are basic dosimetric characteristics for the formation of the dose calculation algorithms parameters and for determination of beam quality. One characteristic of the beam profiles as a measure for the beam quality is the field flatness defined as ratio of the difference of maximum and minimum dose in central 80% of the field to the sum of these doses in the part of the field. The measurements, instead with an ordinary ionization chamber, were performed with a chamber array in two depths (1.6 cm and 10 cm) in water phantom. Nominal photon beam energy was 6 MV and field size was 25 cm x 25 cm on the water surface. Field flatness was in the range of 1-2 % which is in accordance with the data acquired during the acceptance testing and commissioning of the accelerators. with the array chamber the beam profiles can be performed quickly and preciously. These features recommend a chamber array as an excellent tool for periodic quality control of beam profiles. (Author)

Modelling the species distribution of flat-headed cats (Prionailurus planiceps, an endangered South-East Asian small felid.

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Andreas Wilting

Full Text Available BACKGROUND: The flat-headed cat (Prionailurus planiceps is one of the world's least known, highly threatened felids with a distribution restricted to tropical lowland rainforests in Peninsular Thailand/Malaysia, Borneo and Sumatra. Throughout its geographic range large-scale anthropogenic transformation processes, including the pollution of fresh-water river systems and landscape fragmentation, raise concerns regarding its conservation status. Despite an increasing number of camera-trapping field surveys for carnivores in South-East Asia during the past two decades, few of these studies recorded the flat-headed cat. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we designed a predictive species distribution model using the Maximum Entropy (MaxEnt algorithm to reassess the potential current distribution and conservation status of the flat-headed cat. Eighty-eight independent species occurrence records were gathered from field surveys, literature records, and museum collections. These current and historical records were analysed in relation to bioclimatic variables (WorldClim, altitude (SRTM and minimum distance to larger water resources (Digital Chart of the World. Distance to water was identified as the key predictor for the occurrence of flat-headed cats (>50% explanation. In addition, we used different land cover maps (GLC2000, GlobCover and SarVision LLC for Borneo, information on protected areas and regional human population density data to extract suitable habitats from the potential distribution predicted by the MaxEnt model. Between 54% and 68% of suitable habitat has already been converted to unsuitable land cover types (e.g. croplands, plantations, and only between 10% and 20% of suitable land cover is categorised as fully protected according to the IUCN criteria. The remaining habitats are highly fragmented and only a few larger forest patches remain. CONCLUSION/SIGNIFICANCE: Based on our findings, we recommend that future conservation

Theoretical and Field Experimental Investigation of an Arrayed Solar Thermoelectric Flat-Plate Generator

Science.gov (United States)

Rehman, Naveed ur; Siddiqui, Mubashir Ali

2018-05-01

This work theoretically and experimentally investigated the performance of an arrayed solar flat-plate thermoelectric generator (ASFTEG). An analytical model, based on energy balances, was established for determining load voltage, power output and overall efficiency of ASFTEGs. An array consists of TEG devices (or modules) connected electrically in series and operating in closed-circuit mode with a load. The model takes into account the distinct temperature difference across each module, which is a major feature of this model. Parasitic losses have also been included in the model for realistic results. With the given set of simulation parameters, an ASFTEG consisting of four commercially available Bi2Te3 modules had a predicted load voltage of 200 mV and generated 3546 μW of electric power output. Predictions from the model were in good agreement with field experimental outcomes from a prototype ASFTEG, which was developed for validation purposes. Later, the model was simulated to maximize the performance of the ASFTEG by adjusting the thermal and electrical design of the system. Optimum values of design parameters were evaluated and discussed in detail. Beyond the current limitations associated with improvements in thermoelectric materials, this study will eventually lead to the successful development of portable roof-top renewable TEGs.

Adsorption of branched and dendritic polymers onto flat surfaces: A Monte Carlo study

International Nuclear Information System (INIS)

Sommer, J.-U.; Kłos, J. S.; Mironova, O. N.

2013-01-01

Using Monte Carlo simulations based on the bond fluctuation model we study the adsorption of starburst dendrimers with flexible spacers onto a flat surface. The calculations are performed for various generation number G and spacer length S in a wide range of the reduced temperature τ as the measure of the interaction strength between the monomers and the surface. Our simulations indicate a two-step adsorption scenario. Below the critical point of adsorption, τ c , a weakly adsorbed state of the dendrimer is found. Here, the dendrimer retains its shape but sticks to the surface by adsorbed spacers. By lowering the temperature below a spacer-length dependent value, τ*(S) c , a step-like transition into a strongly adsorbed state takes place. In the flatly adsorbed state the shape of the dendrimer is well described by a mean field model of a dendrimer in two dimensions. We also performed simulations of star-polymers which display a simple crossover-behavior in full analogy to linear chains. By analyzing the order parameter of the adsorption transition, we determine the critical point of adsorption of the dendrimers which is located close to the critical point of adsorption for star-polymers. While the order parameter for the adsorbed spacers displays a critical crossover scaling, the overall order parameter, which combines both critical and discontinuous transition effects, does not display simple scaling. The step-like transition from the weak into the strong adsorbed regime is confirmed by analyzing the shape-anisotropy of the dendrimers. We present a mean-field model based on the concept of spacer adsorption which predicts a discontinuous transition of dendrimers due to an excluded volume barrier. The latter results from an increased density of the dendrimer in the flatly adsorbed state which has to be overcome before this state is thermodynamically stable

Adsorption of branched and dendritic polymers onto flat surfaces: A Monte Carlo study

Energy Technology Data Exchange (ETDEWEB)

Sommer, J.-U. [Leibniz Institute of Polymer Research Dresden e. V., 01069 Dresden (Germany); Institute for Theoretical Physics, Technische Universität Dresden, 01069 Dresden (Germany); Kłos, J. S. [Leibniz Institute of Polymer Research Dresden e. V., 01069 Dresden (Germany); Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Mironova, O. N. [Leibniz Institute of Polymer Research Dresden e. V., 01069 Dresden (Germany)

2013-12-28

Using Monte Carlo simulations based on the bond fluctuation model we study the adsorption of starburst dendrimers with flexible spacers onto a flat surface. The calculations are performed for various generation number G and spacer length S in a wide range of the reduced temperature τ as the measure of the interaction strength between the monomers and the surface. Our simulations indicate a two-step adsorption scenario. Below the critical point of adsorption, τ{sub c}, a weakly adsorbed state of the dendrimer is found. Here, the dendrimer retains its shape but sticks to the surface by adsorbed spacers. By lowering the temperature below a spacer-length dependent value, τ*(S) < τ{sub c}, a step-like transition into a strongly adsorbed state takes place. In the flatly adsorbed state the shape of the dendrimer is well described by a mean field model of a dendrimer in two dimensions. We also performed simulations of star-polymers which display a simple crossover-behavior in full analogy to linear chains. By analyzing the order parameter of the adsorption transition, we determine the critical point of adsorption of the dendrimers which is located close to the critical point of adsorption for star-polymers. While the order parameter for the adsorbed spacers displays a critical crossover scaling, the overall order parameter, which combines both critical and discontinuous transition effects, does not display simple scaling. The step-like transition from the weak into the strong adsorbed regime is confirmed by analyzing the shape-anisotropy of the dendrimers. We present a mean-field model based on the concept of spacer adsorption which predicts a discontinuous transition of dendrimers due to an excluded volume barrier. The latter results from an increased density of the dendrimer in the flatly adsorbed state which has to be overcome before this state is thermodynamically stable.