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Sample records for reducing tube current

  1. Reduced radiation exposure to the mammary glands in thoracic computed tomography using organ-based tube-current modulation

    International Nuclear Information System (INIS)

    Munechika, Jiro; Ohgiya, Yoshimitsu; Gokan, Takehiko; Hashimoto, Toshi; Iwai, Tsugunori

    2013-01-01

    Organ-based tube-current modulation has been used to reduce radiation exposure to specific organs. However, there are no reports yet published on reducing radiation exposure in clinical cases. In this study, we assessed the reduction in radiation exposure to the mammary glands during thoracic computed tomography (CT) using X-CARE. In a phantom experiment, the use of X-CARE reduced radiation exposure at the midline of the precordial region by a maximum of 45.1%. In our corresponding clinical study, CT was performed using X-CARE in 15 patients, and without X-CARE in another 15. Compared to the non-X-CARE group, radiation exposure was reduced in the X-CARE group at the midline of the precordial region by 22.3% (P 0.05). X-CARE thus reduced radiation exposure at the midline of the precordial region and allowed us to obtain consistent CT values without increasing noise. However, this study revealed increases in radiation exposure at the lateral sides of the breasts. It is conceivable that patients' breasts were laterally displaced by gravity under the standard thoracic imaging conditions. Further studies that consider factors such as body size and adjustment of imaging conditions may be needed in the future. (author)

  2. Eddy current testing of heat exchangers tubes

    International Nuclear Information System (INIS)

    Gouez, J.F.; Rieusset, A.; Groix, F.

    An automatic system for Eddy Current testing of heat exchangers tubes of warships was developed. The advantages are an exposure of the controller limited at the time required to put in place the system and a reduced time of control [fr

  3. Eddy current inspection of tubing

    International Nuclear Information System (INIS)

    Bauza, J. L. R.; Herrero, J.; Diaz, J.

    1966-01-01

    The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)

  4. X-ray tube current control

    International Nuclear Information System (INIS)

    Dupuis, W.A.; Resnick, T.A.

    1982-01-01

    A closed loop feedback system for controlling the current output of an x-ray tube. The system has circuitry for improving the transient response and stability of the x-ray tube current over a substantial nonlinear portion of the tube current production characteristic. The system includes a reference generator for applying adjustable step function reference signals representing desired tube currents. The system also includes means for instantaneous sensing of actual tube current. An error detector compares the value of actual and reference tube current and produces an error signal as a function of their difference. The system feedback loop includes amplification circuitry for controlling x-ray tube filament dc voltage to regulate tube current as a function of the error signal value. The system also includes compensation circuitry, between the reference generator and the amplification circuitry, to vary the loop gain of the feedback control system as a function of the reference magnitude

  5. Thin tube testing by eddy currents

    International Nuclear Information System (INIS)

    David, Bernard; Pigeon, Michel

    1981-01-01

    It is often necessary to define test conditions in eddy current testing, in consequence rules and laws allowing a rapid choice of these conditions are welcome. The similarity law, given by Forster, using the reduced frequency f/fg, allows extrapolation of results from an object to one another, if these two objects are similar (i.e. all their dimensions are proportional). In a particular case, often met, a law going further is given to describe, in a sole way, eddy current behaviour using the reduced frequency in all thin tubes (internal to external diameter ratio between 0.85 to 1). For instance working at f/fe=2 defines the same verification leading to identical results, whatever the nature, the diameter or the thickness may be, if the tubes are thin. A diagram is given and a slide-rule, based on this principle, has been realized [fr

  6. Eddy current tube testing unit

    International Nuclear Information System (INIS)

    Dufayet, J.P.; Duret, G.

    1975-01-01

    The unit described can check a wide variety of tubes in quick succession and its modular design gives it a high degree of versability. Suitably defined working conditions and specific fittings enable most of the faults encountered in the manufacture of a tube to be detected. By appropriate means of selection based on signal amplitude, phase and frequency analyses it is possible to adapt selection criteria to the seriousness of the different categories of defect [fr

  7. Ion exchange currents in vacuum accelerator tubes

    International Nuclear Information System (INIS)

    Eastham, D.A.; Thorn, R.

    1978-01-01

    Ion exchange currents (microdischarges) have been observed in short lengths of accelerator tube. The occurrence of these discharges can be related to the trajectories of ions in the tube. High-resolution mass spectra of the negative and positive ion components have been obtained. (author)

  8. Testing and analysis of tube voltage and tube current in the radiation generator for mammography

    International Nuclear Information System (INIS)

    Jung, Hong Ryang; Hong, Dong Hee; Han, Beom Hui

    2014-01-01

    Breast shooting performance management and quality control of the generator is applied to the amount of current IEC(International Electrotechnical Commission) 60601-2-45 tube voltage and tube current are based on standards that were proposed in the analysis of the test results were as follows. Tube voltage according to the value of the standard deviation by year of manufacture from 2001 to 2010 as a 42-3.15 showed the most significant, according to the year of manufacture by tube amperage value of the standard deviation to 6.38 in the pre-2000 showed the most significant , manufactured after 2011 the standard deviation of the devices, the PAE(Percent Average Error) was relatively low. This latest generation device was manufactured in the breast of the tube voltage and tube diagnosed shooting the correct amount of current to maintain the performance that can be seen. The results of this study as the basis for radiography diagnosed breast caused by using the device's performance and maintain quality control, so the current Food and Drug Administration 'about the safety of diagnostic radiation generator rule' specified in the test cycle during three years of self-inspection radiation on a radiation generating device ensure safety and performance of the device using a coherent X-ray(constancy) by two ultimately able to keep the radiation dose to the public to reduce the expected effect is expected

  9. Reduced order model of draft tube flow

    International Nuclear Information System (INIS)

    Rudolf, P; Štefan, D

    2014-01-01

    Swirling flow with compact coherent structures is very good candidate for proper orthogonal decomposition (POD), i.e. for decomposition into eigenmodes, which are the cornerstones of the flow field. Present paper focuses on POD of steady flows, which correspond to different operating points of Francis turbine draft tube flow. Set of eigenmodes is built using a limited number of snapshots from computational simulations. Resulting reduced order model (ROM) describes whole operating range of the draft tube. ROM enables to interpolate in between the operating points exploiting the knowledge about significance of particular eigenmodes and thus reconstruct the velocity field in any operating point within the given range. Practical example, which employs axisymmetric simulations of the draft tube flow, illustrates accuracy of ROM in regions without vortex breakdown together with need for higher resolution of the snapshot database close to location of sudden flow changes (e.g. vortex breakdown). ROM based on POD interpolation is very suitable tool for insight into flow physics of the draft tube flows (especially energy transfers in between different operating points), for supply of data for subsequent stability analysis or as an initialization database for advanced flow simulations

  10. Comparison radiation dose of Z-axis automatic tube current modulation technique with fixed tube current multi-detector row CT scanning of lower extremity venography

    International Nuclear Information System (INIS)

    Yoo, Beong Gyu; Kweon, Dae Cheol; Lee, Jong Seok; Jang, Keun Jo; Jeon, Sang Hwan; Kim, Yong Soo

    2007-01-01

    Z-axis automatic tube current modulation technique automatically adjusts tube current based on size of body region scanned. The purpose of the current study was to compare noise, and radiation dose of Multi-Detector row CT (MDCT) of lower extremity performed with Z-axis modulation technique of automatic tube current modulation with manual selection fixed tube current. Fifty consecutive underwent MDCT venography of lower extremity with use of a MDCT scanner fixed tube current and Z-axis automatic tube current modulation technique (10, 11 and 12 HU noise index, 70∼450 mA). Scanning parameters included 120 kVp, 0.5 second gantry rotation time, 1.35:1 beam pitch, and 1 mm reconstructed section thickness. For each subject, images obtained with Z-axis modulation were compared with previous images obtained with fixed tube current (200, 250, 300 mA) and with other parameters identical. Images were compared for noise at five levels: iliac, femoral, popliteal, tibial, and peroneal vein of lower extremity. Tube current and gantry rotation time used for acquisitions at these levels were recorded. All CT examinations of study and control groups were diagnostically acceptable, though objective noise was significantly more with Z-axis automatic tube current modulation. Compared with fixed tube current, Z-axis modulation resulted in reduction of CTDIvol (range, -6.5%∼-35.6%) and DLP (range,-0.2%∼-20.2%). Compared with manually selected fixed tube current, Z-axis automatic tube current modulation resulted in reduced radiation dose at MDCT of lower extremity venography

  11. Eddy current testing of steam generator tubes

    International Nuclear Information System (INIS)

    Neumaier, P.

    1981-01-01

    A rotating probe is described for improving the inspection of tubes and end plate in steam generators. The method allows a representation of the whole defect, consequently the observer is able to determine directly the type of defect, signal processing in-line or off-line is possible [fr

  12. Problems and limitations of eddy current tube inspection

    International Nuclear Information System (INIS)

    Ilham Mukriz Zainal Abidin; Khairul Anuar Mohd Salleh; Mohamed Hairul Hasmoni

    2003-01-01

    Incomplete appreciation of eddy current limitations has contributed to both under-utilization and misapplication of the technique. A brief review on the physical principle of eddy current is presented. Eddy current technique in identifying inhomogeneity in tested tubes is discussed, highlighting its limitation in distinguishing between real pit type defects and other mundane anomalies. The variables responsible for limitation in eddy current tube inspection are discussed and alternative approaches, where they exist, are suggested. (Author)

  13. Multifrequency eddy current testing of helical tubes of steam generators

    International Nuclear Information System (INIS)

    Pigeon, M.; David, B.

    1983-06-01

    In the event of a water-sodium reaction in a steam-generator of a fast breeder reactor, it is necessary to test the tubes close to the leak to evaluate the damage. In SUPERPHENIX, the tubes are about 100m long and are coiled on a dead body. This report describes the equipment and the technic to test such tubes with multifrequency eddy current technics [fr

  14. Eddy current inspection on heat exchanger tubes - problems and limitations

    International Nuclear Information System (INIS)

    Ilham Mukriz; Zainal Abidin Mohamed; Hairul Hasmoni Khairul Anuar; Mohd Salleh; Mahmood Dollah

    2005-01-01

    This paper focus on problems associated to eddy current inspection of heat exchanger tubes. A brief review on heat exchanger design and operation is presented. Eddy current technique in identifying inhomogeneity in tested tubes is discussed, highlighting its limitation in distinguishing between real pit type defects and other mundane anomalies. The limitation of the eddy current probe and equipment pertinent to the inspection are identified and areas of improvement are discussed. (Author)

  15. Eddy current detection of corrosion damage in heat exchanger tubes

    International Nuclear Information System (INIS)

    Van Drunen, G.; Cecco, V.S.; Carter, J.R.

    1980-05-01

    Eddy current is often the most effective nondestructive test method available for in-service inspection of small bore tubing in heat exchangers. The basic principles, advantages and shortcomings of the technique are outlined. Typical eddy current indications from corrosion-related defects such as stress corrosion cracks, pitting and tube denting under support plates are presented. Eddy current signals from features such as magnetite deposits and ferromagnetic inclusions which might be mistaken for defects are also discussed. (auth)

  16. Annular gap measurement between pressure tube and calandria tube by eddy current technique

    International Nuclear Information System (INIS)

    Bhole, V.M.; Rastogi, P.K.; Kulkarni, P.G.

    1992-01-01

    In pressurised heavy water reactor (PHWR) major distinguishing feature is that there are number of identical fuel channels in the reactor core. Each channel consists of pressure tube of Zr-2.5 Nb or zircaloy-2 through which high temperature, high pressure primary coolant is passing. The pressure tube contains fuel. Surrounding the pressure tube there is low pressure, cool heavy water (moderator). The moderator is thermally separated from coolant by the tube which is nominally concentric with pressure tube called calandria tube. There are four garter springs in the annular gap between pressure tube and calandria tube. During the life of the reactor there are number of factors by which the pressure tube sags, most important factors are irradiation creep, thermal creep, fuel load etc. Because of the sag of pressure tube it can touch the calandria tube resulting in formation of cold spot. This leads to hydrogen concentration at that spot by which the material at that place becomes brittle and can lead to catastrophic failure of pressure tube. There is no useful access for measurement of annular gap either through the gas annular space or from exterior of calandria tube. So the annular gap was measured from inside surface of pressure tube which is accessible. Eddy current technique was used for finding the gap. The paper describe the details of split coil design of bobbin probe, selection of operating point on normalised impedance diagram by choosing frequency. Experimental results on full scale mock up, and actual gap measurement in reactor channel, are also given. (author). 7 figs

  17. Eddy current technique applied to automated tube profilometry

    International Nuclear Information System (INIS)

    Dobbeni, D.; Melsen, C. van

    1982-01-01

    The use of eddy current methods in the first totally automated pre-service inspection of the internal diameter of PWR steam generator tubes is described. The technique was developed at Laborelec, the Belgian Laboratory of the Electricity Supply Industry. Details are given of the data acquisition system and of the automated manipulator. Representative tube profiles are illustrated. (U.K.)

  18. Remote field eddy current testing of ferromagnetic tubes

    International Nuclear Information System (INIS)

    David, B.

    1990-01-01

    In order to test ferromagnetic tubes using internal probes, Intercontrole and the CEA have carried out theoretical and experimental works and developed a method to adapt the Remote Field Eddy Current technique which has been known and used for 30 years now. This document briefly recalls the basic principles of the Remote Field Eddy Current technique, the various steps of the works carried out and mainly describes examples of field inspection of ferromagnetic tubes and pipes [fr

  19. Dose reduction in subsecond multislice spiral CT examination of children by online tube current modulation

    International Nuclear Information System (INIS)

    Greess, H.; Lutze, J.; Noemayr, A.; Bautz, W.; Wolf, H.; Hothorn, T.; Kalender, W.A.

    2004-01-01

    The potential of online tube current modulation in subsecond multislice spiral CT (MSCT) examinations of children to reduce the dose without a loss in image quality is investigated in a controlled patient study. The dose can be reduced for oval patient sectional view without an increase in noise if the tube current is reduced where the patient diameter and, consequently, attenuation are small. We investigated a product version of an online control for tube current in a SOMATOM Sensation 4 (Siemens, Forchheim). We evaluated image quality, noise and dose reduction for examinations with online tube current modulation in 30 MSCT of thorax/abdomen and abdomen and compared mA s for tube current modulation to the mA s in standard weight-adapted children protocols. Image quality was rated as ''very good,'' ''good,'' ''diagnostic'' and ''poor'' in a consensus by three radiologists. Noise was assessed in comparison to 24 MSCT examinations without tube current modulation measured as SD in ROIs. The dose was reduced from 26 to 43% (mean 36%), depending on the patient's geometry and weight. (orig.)

  20. Eddy current inspection of mildly ferromagnetic tubing

    International Nuclear Information System (INIS)

    Mayo, W.R.; Carter, J.R.

    1984-02-01

    The past decade has seen the development of eddy current probes for inspection of the mildly ferro-magnetic alloy Monel 400. Due to the rapid advances in permanent magnet technology similar probes have been upgraded to magnetically saturate, and hence inspect, the duplex stainless steel Sandvik 3RE60, which has saturation induction more than twice that of Monel 400. Prototypes of these probes have been tested in three ways: saturation capability, quality of typical eddy current data, and ability to eliminate permeability induced signals. Successful laboratory testing, potential applications, and limitations of these type probes are discussed

  1. Performance demonstration requirements for eddy current steam generator tube inspection

    International Nuclear Information System (INIS)

    Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.

    1992-10-01

    This paper describes the methodology used for developing performance demonstration tests for steam generator tube eddy current (ET) inspection systems. The methodology is based on statistical design principles. Implementation of a performance demonstration test based on these design principles will help to ensure that field inspection systems have a high probability of detecting and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented. Probability of detection and flaw sizing tests are described

  2. CURRENT BUILDUP IN EMERGING SERPENTINE FLUX TUBES

    International Nuclear Information System (INIS)

    Pariat, E.; Masson, S.; Aulanier, G.

    2009-01-01

    The increase of magnetic flux in the solar atmosphere during active-region formation involves the transport of the magnetic field from the solar convection zone through the lowest layers of the solar atmosphere, through which the plasma β changes from >1 to <1 with altitude. The crossing of this magnetic transition zone requires the magnetic field to adopt a serpentine shape also known as the sea-serpent topology. In the frame of the resistive flux-emergence model, the rising of the magnetic flux is believed to be dynamically driven by a succession of magnetic reconnections which are commonly observed in emerging flux regions as Ellerman bombs. Using a data-driven, three-dimensional (3D) magnetohydrodynamic numerical simulation of flux emergence occurring in active region 10191 on 2002 November 16-17, we study the development of 3D electric current sheets. We show that these currents buildup along the 3D serpentine magnetic-field structure as a result of photospheric diverging horizontal line-tied motions that emulate the observed photospheric evolution. We observe that reconnection can not only develop following a pinching evolution of the serpentine field line, as usually assumed in two-dimensional geometry, but can also result from 3D shearing deformation of the magnetic structure. In addition, we report for the first time on the observation in the UV domain with the Transition Region and Coronal Explorer (TRACE) of extremely transient loop-like features, appearing within the emerging flux domain, which link several Ellermam bombs with one another. We argue that these loop transients can be explained as a consequence of the currents that build up along the serpentine magnetic field.

  3. Eddy current inspection of steam generator tubing plugs

    International Nuclear Information System (INIS)

    Cullen, W.K.

    1990-01-01

    In response to the issues raised regarding the integrity of nuclear steam generator tubing plugs manufactured from certain heats of Inconel 600, Westinghouse engineers have developed, qualified and implemented an eddy current inspection system for the in-place assessment of these plugs. The heart of the system is a robotic and effector which delivers an eddy current sensor through the reduced diameter of the plug expander and actuates the coil to physical contact with the expanded inside bore of the plug. Once deployed, the eddy current sensor is rotated along a helical path to produce a detailed scan of the plug surface above the final position of the expander. This testing produces an isometric display of degradation due to primary water stress corrosion cracking, on the inside surface of the plug. To date, successful inspections have been conducted at two nuclear units with two different robotic delivery systems. While designed specifically for mechanical plugs with a bottle bore cavity, the inspection system can also be used for expanded straight bore plugs. Details of the inspection system along with a discussion of qualification activities and actual field results are presented in this paper

  4. Reducing tube bundle deposition with alternative amines

    International Nuclear Information System (INIS)

    Turner, C.W.; Klimas, S.J.; Frattini, P.L.

    1998-01-01

    Particle deposition rates have been measured in a high-temperature loop for magnetite and hematite depositing onto Inconel-600 under flow-boiling conditions with pH controlled using one of the following amines: morpholine, ammonia, ethanolamine, or dimethylamine. Hematite particles deposited at rates an order of magnitude greater than those measured for magnetite, although the hematite deposition rate dropped when the loop was operated under reducing conditions. The magnetite deposition rate was influenced by the amine used to control the pH, with the relative rate decreasing in the following series: morpholine (1) : ethanolamine (0.72) ammonia (0.51) : dimethylamine (0.25). These trends in deposition rate are discussed in terms of the surface chemistry of the corrosion products. Deposition rates for both magnetite and hematite increased significantly once the mixture quality exceeded about 0.3, which may be related to a change in the heat transfer mechanism from nucleate boiling to two-phase forced convection through a thin film. (author)

  5. Reducing tube bundle deposition using alternative amines

    International Nuclear Information System (INIS)

    Turner, C.W.; Klimas, S.J.; Frattini, P.L.

    1999-07-01

    Particle deposition rates were measured in a high-temperature loop for magnetite and hematite depositing onto Inconel-600 under flow-boiling conditions with pH controlled, using one of the following amines: morpholine, ammonia, ethanolamine, or dimethylamine. Hematite particles deposited at rates 10 times greater than those measured for magnetite although the hematite deposition rate dropped when the loop was operated under reducing conditions. The magnetite deposition rate was influenced by the amine used to control the pH, with the relative rate decreasing in the following series: morpholine (1) : ethanolamine (0.72) : ammonia (0.51) dimethylamine (0.25). These trends in deposition rate are discussed in terms of the surface chemistry of the corrosion products. Deposition rates for both magnetite and hematite increased significantly once the mixture quality exceeded about 0.3, which may be related to a change in the heat-transfer mechanism from nucleate boiling to 2-phase forced-convection through a thin film. (author)

  6. Validating eddy current array probes for inspecting steam generator tubes

    International Nuclear Information System (INIS)

    Sullivan, S.P.; Cecco, V.S.; Obrutsky, L.S.

    1997-01-01

    A CANDU nuclear reactor was shut down for over one year because steam generator (SG) tubes had failed with outer diameter stress-corrosion cracking (ODSCC) in the U-bend section. Novel, single-pass eddy current transmit-receive probes, denoted as C3, were successful in detecting all significant cracks so that the cracked tubes could be plugged and the unit restarted. Significant numbers of tubes with SCC were removed from a SG in order to validate the results of the new probe. Results from metallurgical examinations were used to obtain probability-of-detection (POD) and sizing accuracy plots to quantify the performance of this new inspection technique. Though effective, the above approach of relying on tubes removed from a reactor is expensive, in terms of both economic and radiation-exposure costs. This led to a search for more affordable methods to validate inspection techniques and procedures. Methods are presented for calculating POD curves based on signal-to-noise studies using field data. Results of eddy current scans of tubes with laboratory-induced ODSCC are presented with associated POD curves. These studies appear promising in predicting realistic POD curves for new inspection technologies. They are being used to qualify an improved eddy current array probe in preparation for field use. (author)

  7. Eddy current test of fin tubes for a heat exchanger

    International Nuclear Information System (INIS)

    KIm, Young Joo; Lee, Se Kyung; Chung, Min Hwa

    1992-01-01

    Eddy current probes were designed for the test of fin tubes. Fin tubes, often used for heat exchangers, have uneven outer and inner surfaces to enhance the heat emission. The surface roughness make it difficult to detect flaws employing eddy current test(ECT). In order to overcome the difficulties we performed two types of works, one is the delopment of ECT probes, and the other is the signal processing including fast Fourier transform and digital filtering. In the development of ECT probes, we adopted empirical design method. Our ECT probes for fin tubes are inside diameter type. And we are specially concerned about geometric features such as the widths of the coils composing an ECT probe. We fabricated four probes with various coil widths. Eddy current test was performed using those ECT probes on specimens with artificial flaws. After analyzing the output signals, we found that, in order for the effective testing, the width of a coil should be determined considering the pitch of the fins of a tube. And we also learned that the frequency filtering could improve the s/n ratio.

  8. Eddy current inspection of weld defects in tubing

    Science.gov (United States)

    Katragadda, G.; Lord, W.

    1992-01-01

    An approach using differential probes for the inspection of weld defects in tubing is studied. Finite element analysis is used to model the weld regions and defects. Impedance plane signals are predicted for different weld defect types and compared wherever possible with signals from actual welds in tubing. Results show that detection and sizing of defects in tubing is possible using differential eddy current techniques. The phase angle of the impedance plane trajectory gives a good indication of the sizing of the crack. Data on the type of defect can be obtained from the shape of the impedance plane trajectory and the phase. Depending on the skin depth, detection of outer wall, inner wall, and subsurface defects is possible.

  9. Reliability of eddy current examination of steam generator tubes

    International Nuclear Information System (INIS)

    Birks, A.S.; Ferris, R.H.; Doctor, P.G.; Clark, R.A.; Spanner, G.E.

    1985-04-01

    A unique study of nondestructive examination reliability is underway at the Pacific Northwest Laboratory under US Nuclear Regulatory Commission sponsorship. Project participants include the Electric Power Research Institute and consortiums from France, Italy, and Japan. This study group has conducted a series of NDE examinations of tubes from a retired-from-service steam generator, using commercially available multifrequency eddy current equipment and ASME procedures. The examination results have been analyzed to identify factors contributing to variations in NDE inspection findings. The reliability of these examinations will then be validated by destructive analyses of the steam generator tubes. The program is expected to contribute to development of a model for steam generator inservice inspection sampling plans and inspection periods, as well as to improved regulatory guidelines for tube plugging

  10. New tube fitting range can slash assembly time, reduce tube material costs and eliminate hot work

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2008-09-15

    Parker Instrumentation has developed a permanent tube connection technology known as Phastite for use in high pressure applications such as in the offshore oil and gas sector. The Phastite push-fit connector offers major savings over traditional permanent and higher pressure connection techniques such as welded or cone-and-thread tube fittings. It also reduces assembly times by 20-fold or more and eliminates the need for hot work permits. The fittings are designed to withstand working pressures up to 1,379 bar. Phastite tube fittings can be used on offshore platforms, as well as on support vessels,, subsea equipment and ROVs such as hydraulic systems for wellhead control, emergency shut down, chemical injection, pumping packages, gas booster systems and test equipment. The connectors offer considerable savings in material cost and weight because they do not need to be used with more expensive tubing with extra thickness to accommodate a thread. Phastite is also resistant to vibration and does not need any anti-vibration accessories. A joint can be made in a matter of seconds with a simple handheld hydraulic tool that makes the push-fit connection. A sealing mechanism based on a series of defined internal ridges creates a secure seal by radial compression. The ridges grip in a way that retains all of the tubing's strength. An additional characteristic is the maintenance free nature of the Phastite connection. 1 fig.

  11. Current Status on the Development of a Double Wall Tube Steam Generator

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ho Yun; Choi, Byoung Hae; Kim, Jong Man; Kim, Byung Ho

    2007-12-15

    A fast reactor, which uses sodium as a coolant, has a lot of merits as a next generation nuclear reactor. However, the possibility of a sodium-water reaction occurrence hinders the commercialization of this reactor. As one way to improve the reliability of a steam generator, a double-wall tube steam generator is being developed in GEN-4 program. In this report, the current state of the technical developments for a double-wall tube steam generator are reviewed and a future plan for the development of a double-wall tube steam generator is established. The current focuses of this research are an improvement of the heat transfer capability for a double-wall tube and the development of a proper leak detection method for the failure of a double-wall tube during a reactor operation. The ideal goal is an on-line leak detection of a double wall tube to prevent the sodium-water reaction. However, such a method is not developed as yet. An alternative method is being used to improve the reliability of a steam generator by performing a non-destructive test of a double wall tube during the refueling period of a reactor. In this method a straight double wall tube is employed to perform this test easily, but has a difficulty regarding an absorption of a thermal expansion of the used materials. If an on-line leak detection method is developed, the demerits of a straight double-wall tube are avoided by using a helical type double-wall tube, and the probability of a sodium-water reaction can be reduced to a level less than the design-based accident.

  12. Comparison of image quality and radiation dose between combined automatic tube current modulation and fixed tube current technique in CT of abdomen and pelvis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sanghee (Dept. of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan Univ. School of Medicine (Korea, Republic of)); Yoon, Sang-Wook; Yoo, Seung-Min; Kim, Kyoung Ah; Kim, Sang Heum; Lee, Jong Tae (Dept. of Diagnostic Radiology, CHA Bundang Medical Center, CHA Univ. (Korea, Republic of)), email: jansons@cha.ac.kr; Ji, Young Geon (Preventive Medicine, CHA Bundang Medical Center, CHA Univ. (Korea, Republic of))

    2011-12-15

    Background. Tube current is an important determinant of radiation dose and image quality in X-ray-based examination. The combined automatic tube current modulation technique (ATCM) enables automatic adjustment of the tube current in various planes (x-y and z) based on the size and attenuation of the body area scanned. Purpose. To compare image quality and radiation dose of the ATCM with those of a fixed tube current technique (FTC) in CT of the abdomen and pelvis performed with a 16-slice multidetector row CT. Material and Methods. We reviewed 100 patients in whom initial and follow-up CT of the abdomen and pelvis were performed with FTC and ATCM. All acquisition parameters were identical in both techniques except for tube current. We recorded objective image noise in liver parenchyma, subjective image noise and diagnostic acceptability by using a five-point scale, radiation dose, and body mass index (BMI, kg/m2). Data were analyzed with parametric and non-parametric statistical tests. Results. There was no significant difference in image noise and diagnostic acceptability between two techniques. All subjects had acceptable subjective image noise in both techniques. The significant reduction in radiation dose (45.25% reduction) was noted with combined ATCM (P < 0.001). There was a significant linear statistical correlation between BMI and dose reduction (r = -0.78, P < 0.05). Conclusion. The ATCM for CT of the abdomen and pelvis substantially reduced radiation dose while maintaining diagnostic image quality. Patients with lower BMI showed more reduction in radiation dose

  13. Eddy current proximity measurement of perpendicular tubes from within pressure tubes in CANDU nuclear reactors

    Science.gov (United States)

    Bennett, P. F. D.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2018-04-01

    Fuel channels in CANDU® (CANada Deuterium Uranium) nuclear reactors consist of two non-concentric tubes; an inner pressure tube (PT) and a larger diameter calandria tube (CT). Up to 400 horizontally mounted fuel channels are contained within a calandria vessel, which also holds the heavy water moderator. Certain fuel channels pass perpendicularly over horizontally oriented tubes (nozzles) that are part of the reactor's liquid injection shutdown system (LISS). Due to sag, these fuel channels are at risk of coming into contact with the LISS nozzles. In the event of contact between the LISS nozzle and CT, flow-induced vibrations from within the moderator could lead to fretting and deformation of the CT. LISS nozzle proximity to CTs is currently measured optically from within the calandria vessel, but from outside the fuel channels. Measurement by an independent means would provide confidence in optical results and supplement cases where optical observations are not possible. Separation of PT and CT, known as gap, is monitored from within the PT using a transmit-receive eddy current probe. Investigation of the eddy current based gap probe as a tool to also measure proximity of LISS nozzles was carried out experimentally in this work. Eddy current response as a function of LISS-PT proximity was recorded. When PT-CT gap, PT wall thickness, PT resistivity and probe lift-off variations were not present this dependence could be used to determine the LISS-PT proximity. This method has the potential to provide LISS-CT proximity using existing gap measurement data. Obtaining LISS nozzle proximity at multiple inspection intervals could be used to provide an estimate of the time to LISS-CT contact, and thereby provide a means of optimizing maintenance schedules.

  14. Effect of tube current modulation for dose estimation using a simulation tool on body CT examination

    International Nuclear Information System (INIS)

    Kawaguchi, Ai; Matsunaga, Yuta; Kobayashi, Masanao; Suzuki, Shoichi; Matsubara, Kosuke; Chida, Koichi

    2015-01-01

    The purpose of this study was to evaluate the effect of tube current modulation for dose estimation of a body computed tomography (CT) examination using a simulation tool. The authors also compared longitudinal variations in tube current values between iterative reconstruction (IR) and filtered back-projection (FBP) reconstruction algorithms. One hundred patients underwent body CT examinations. The tube current values around 10 organ regions were recorded longitudinally from tube current information. The organ and effective doses were simulated by average tube current values and longitudinal modulated tube current values. The organ doses for the bladder and breast estimated by longitudinal modulated tube current values were 20 % higher and 25 % lower than those estimated using the average tube current values, respectively. The differences in effective doses were small (mean, 0.7 mSv). The longitudinal variations in tube current values were almost the same for the IR and FBP algorithms. (authors)

  15. The effects of bismuth breast shields in conjunction with automatic tube current modulation in CT imaging

    International Nuclear Information System (INIS)

    Servaes, Sabah; Zhu, Xiaowei

    2013-01-01

    There are mechanisms within CT scanners and shielding that can be used to lower dose to patients. The objective of our study was to evaluate the dose changes and image quality with and without a breast shield for multidetector CT of the chest with angular tube current modulation. An anthropomorphic 5-year-old phantom was scanned with and without bismuth breast shielding and with and without angular tube current modulation. Image quality was assessed by measuring signal-to-noise ratio and contrast-to-noise ratio as well as measuring qualitatively. ANOVA single-factor p-value analysis of paired datasets was used for the statistical analysis. The breast shielding and angular tube current modulation resulted in a dose reduction to 85% for the breast and 90% overall. Although no qualitative differences were noted with and without the breast shielding used with angular tube current modulation, there were statistically significant differences in the contrast-to-noise ratio and CT numbers. When used with angular tube current modulation, breast shields influence the contrast-to-noise ratio and CT numbers, and therefore should not be used for chest CT. Greater dose reduction can be obtained by reducing the reference mAs (or reference noise index). (orig.)

  16. Considerations on an automatic computed tomography tube current modulation system

    International Nuclear Information System (INIS)

    Moro, L.; Panizza, D.; D'Ambrosio, D.; Carne, I.

    2013-01-01

    The scope of this study was to evaluate the effects on radiation output and image noise varying the acquisition parameters with an automatic tube current modulation (ATCM) system in computed tomography (CT). Chest CT examinations of an anthropomorphic phantom were acquired using a GE LightSpeed VCT 64-slice tomograph. Acquisitions were performed using different pitch, slice thickness and noise index (NI) values and varying the orientation of the scanned projection radiograph (SPR). The radiation output was determined by the CT dose index (CTDI vol ). Image noise was evaluated measuring the standard deviation of CT numbers in several regions of interest. The radiation output was lower if the SPR was acquired in the anterior-posterior projection. The radiation dose with the posterior-anterior SPR was higher, because the divergence of the X-ray beam magnifies the anatomical structures closest to the tube, especially the spinal column, and this leads the ATCM system to estimate higher patient attenuation values and, therefore, to select higher tube current values. The NI was inversely proportional to the square root of the CTDI vol and, with fixed NI, the CTDI vol increased as the slice thickness decreased. This study suggests some important issues to use the GE ATCM system efficiently. (authors)

  17. High-current beam transport in electrostatic accelerator tubes

    International Nuclear Information System (INIS)

    Ramian, G.; Elais, L.

    1987-01-01

    The UCSB Free Electron Laser (FEL) has successfully demonstrated the use of a commercial 6 megavolt electrostatic accelerator as a high current beam source in a recirculating configuration. The accelerator, manufactured by National Electrostatics Corp. (NEC), Middleton WI, uses two standard high gradient accelerator tubes. Suppression of ion multiplication was accomplished by NEC with apertures and a shaped electrostatic field. This field shaping has fortuitously provided a periodically reversing radial field component with sufficient focusing strength to transport electron beams of up to 3 Amps current. Present two-stage FEL work requires a 20 Amp beam and proposed very high voltage FEL designs require currents as high as 100 Amps. A plan to permit transport of such high current beams by the addition of solenoidal focussing elements is described

  18. Establishment of a semi-biological phantom model for the study of the effect of dose reducing measures on radiation-induced DNA double strand breaks in CT using the example of risk organ based tube current modulation; Etablierung eines semibiologischen Phantommodells zur Untersuchung des Effekts dosisreduzierender Massnahmen auf strahleninduzierte DNA-Doppelstrangbrueche in der CT am Beispiel der risikoorganbasierten Roehrenstrommodulation

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, Matthias

    2013-12-12

    The number of computed tomography (CT) examinations has been rising during the last decades. Therefore techniques for dose reduction receive increasing attention. Risk organ-based tube current modulation (RCM) in CT is a new approach and works by lowering the tube current, while the tube is in front of the patient's body. Therefore it should lead to a dose reduction for radiosensitive organs like the female breast, the eye lenses and the thyroid gland. Biological radiation effects cannot be estimated by physical-based dose measurements. γ-H2AX is a sensitive marker for the determination of x-ray induced DNA double-strand breaks (DSB). Hence the aim of this study was to establish a biological phantom model based on the γ-H2AX immunofluorescence microscopy method and to investigate the effect of RCM on radiation induced DNA damages. The γ-H2AX method is based on the phosphorylation of the histone variant H2AX. The phosphorylated histone γ-H2AX can be visualised using antibodies and is specific for radiation induced DSB. Blood lymphocytes from healthy volunteers, skin fibroblasts (LN) and mammary epithelial cells (HMEpC-p) were placed in different positions of an Alderson-phantom and exposed to x-rays using a 128-slice dual-source CT scanner. Standard head, neck and chest-CT scan protocols either with or without risk-organ based tube current modulation were used. RCM reduces the tube current to 20 percent at an angle of 130 degree anterior to the body, whereas tube current is increased at an angle of 230 degree posterior to the body. Afterwards cells were isolated, fixed on slides und stained with specific primary γ-H2AX antibodies and fluorescent secondary antibodies. Tiny green dots (named foci) can be detected and quantified with a fluorescence microscope and represent distinct DSB. Non-irradiated samples served as controls and CT-induced DSB were calculated by subtraction of pre- from post-exposure values. In this study a semibiological phantom model

  19. Evaluation of machine learning tools for inspection of steam generator tube structures using pulsed eddy current

    Science.gov (United States)

    Buck, J. A.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2017-02-01

    Degradation of nuclear steam generator (SG) tubes and support structures can result in a loss of reactor efficiency. Regular in-service inspection, by conventional eddy current testing (ECT), permits detection of cracks, measurement of wall loss, and identification of other SG tube degradation modes. However, ECT is challenged by overlapping degradation modes such as might occur for SG tube fretting accompanied by tube off-set within a corroding ferromagnetic support structure. Pulsed eddy current (PEC) is an emerging technology examined here for inspection of Alloy-800 SG tubes and associated carbon steel drilled support structures. Support structure hole size was varied to simulate uniform corrosion, while SG tube was off-set relative to hole axis. PEC measurements were performed using a single driver with an 8 pick-up coil configuration in the presence of flat-bottom rectangular frets as an overlapping degradation mode. A modified principal component analysis (MPCA) was performed on the time-voltage data in order to reduce data dimensionality. The MPCA scores were then used to train a support vector machine (SVM) that simultaneously targeted four independent parameters associated with; support structure hole size, tube off-centering in two dimensions and fret depth. The support vector machine was trained, tested, and validated on experimental data. Results were compared with a previously developed artificial neural network (ANN) trained on the same data. Estimates of tube position showed comparable results between the two machine learning tools. However, the ANN produced better estimates of hole inner diameter and fret depth. The better results from ANN analysis was attributed to challenges associated with the SVM when non-constant variance is present in the data.

  20. Current microbiology of percutaneous endoscopic gastrostomy tube (PEG tube) insertion site infections in patients with cancer.

    Science.gov (United States)

    Rolston, Kenneth V I; Mihu, Coralia; Tarrand, Jeffrey J

    2011-08-01

    Percutaneous endoscopic gastrostomy (PEG) is frequently used to provide enteral access in cancer patients who are unable to swallow. Infection is an important complication in this setting. Current microbiological data are needed to guide infection prevention and treatment strategies. The microbiological records of our institution (a 550-bed comprehensive cancer center) were retrospectively reviewed over an 8-month study period in order to identify patients who developed PEG tube insertion site infections, and review their microbiological details and susceptibility/resistance data. Fifty-eight episodes of PEG tube insertion site infections were identified. Of these, 31 (53%) were monomicrobial, and the rest were polymicrobial. The most common organisms isolated were Candida species, Staphylococcus aureus, and Pseudomonas aeruginosa. All infections were local (cellulitis, complicated skin, and skin structure infections including abdominal wall abscess) with no cases of concomitant bacteremia being documented. Most of the organisms isolated were susceptible to commonly used antimicrobial agents, although some quinolone-resistant and some multidrug-resistant organisms were isolated. This retrospective study provides descriptive data regarding PEG tube insertion site infections. These data have helped us update institutional guidelines for infection prevention and treatment as part of our focus on antimicrobial stewardship.

  1. Eddy current testing device for metallic tubes at least locally curved

    International Nuclear Information System (INIS)

    Pigeon, Marcel; Vienot, Claude.

    1975-01-01

    Steam generators, condensers and heat exchangers generally consist of metallic tube bundles, the tubes having a complex geometry. The invention concerns an Eddy current testing device for metallic tubes at least locally curved, operating by translation of a probe inside the tubes [fr

  2. Current state and development trends of inspections of steam generator tubes by eddy currents method

    International Nuclear Information System (INIS)

    Kubis, S.; Herman, M.

    1988-01-01

    The requirements are presented for steam generator tube testing and the factors are discussed affecting the accuracy of measurement by the eddy currents method. The individual types of the eddy currents method are described, such as the single-frequency method, the multi-frequency method and the pulse eddy currents method. The demands are summed up on manipulator systems whose design is adapted to the steam generator configuration conditions. (E.S.). 5 figs., 16 possu

  3. Method and apparatus for remote tube crevice detection by current and voltage probe resistance measurement

    Science.gov (United States)

    Kikta, Thomas J.; Mitchell, Ronald D.

    1992-01-01

    A method and apparatus for determining the extent of contact between an electrically conducting tube and an electrically conductive tubesheet surrounding the tube, based upon the electrical resistance of the tube and tubesheet. A constant current source is applied to the interior of the electrically conducting tube by probes and a voltmeter is connected between other probes to measure the voltage at the point of current injection, which is inversely proportional to the amount of contact between the tube and tubesheet. Namely, the higher the voltage measured by the voltmeter, the less contact between the tube and tubesheet.

  4. Enhancing tube hydroformability by reducing the local strain gradient at potential necking sites

    International Nuclear Information System (INIS)

    Shin, S. G. R.; Joo, B. D.; Moon, Y. H.; Tyne, C. J. Van

    2014-01-01

    Bursting in tube hydroforming is preceded by localized deformation, which is often called necking. The retardation of the initiation of necking is a means to enhance hydroformability. Since high strain gradients occur at necking sites, a decrease in local strain gradients is an effective way to retard the initiation of necking. In the current study, the expansion at potential necking sites was intentionally restricted in order to reduce the strain gradient at potential necking sites. From the strain distribution obtained from FEM, it is possible to determine strain concentrated zones, which are the potential necking sites. Prior to the hydroforming of a trailing arm, lead patch is attached to the tube where the strain concentration would occur. Due to the incompressibility of lead, the tube expansion is locally restricted, and the resultant strain extends to adjacent regions of the tube during hydroforming. After the first stage of hydroforming, the lead is removed from the tube, and the hydroforming continues to obtain the targeted shape without the local restriction. This method was successfully used to fabricate a complex shaped automotive trailing arm that had previously failed during traditional hydroforming processing.

  5. Optimization of a Two Stage Pulse Tube Refrigerator for the Integrated Current Lead System

    Science.gov (United States)

    Maekawa, R.; Matsubara, Y.; Okada, A.; Takami, S.; Konno, M.; Tomioka, A.; Imayoshi, T.; Hayashi, H.; Mito, T.

    2008-03-01

    Implementation of a conventional current lead with a pulse tube refrigerator has been validated to be working as an Integrated Current Lead (ICL) system for the Superconducting Magnetic Energy Storage (SMES). Realization of the system is primarily accounted for the flexibility of a pulse tube refrigerator, which does not posses any mechanical piston and/or displacer. As for an ultimate version of the ICL system, a High Temperature Superconducting (HTS) lead links a superconducting coil with a conventional copper lead. To ensure the minimization of heat loads to the superconducting coil, a pulse tube refrigerator has been upgraded to have a second cooling stage. This arrangement reduces not only the heat loads to the superconducting coil but also the operating cost for a SMES system. A prototype two-stage pulse tube refrigerator, series connected arrangement, was designed and fabricated to satisfy the requirements for the ICL system. Operation of the first stage refrigerator is a four-valve mode, while the second stage utilizes a double inlet configuration to ensure its confined geometry. The paper discusses the optimization of second stage cooling to validate the conceptual design

  6. Measurement by eddy currents of tube-antivibratory bar gap steam generators of PWR power plants

    International Nuclear Information System (INIS)

    Savin, E.; Bieth, M.; Floze, J.C.

    1990-01-01

    In steam generators tubes are maintained by AVB to limit vibrations amplitude induced by secondary fluid flow. After some years wear sometimes occurs. For gap measurement between tubes and AVB Framatome developed a method based on eddy current and using a probe rotating inside the tube [fr

  7. Improved eddy-current inspection for steam generator tubing

    International Nuclear Information System (INIS)

    Dodd, C.V.; Pate, J.R.; Allen, J.D. Jr.

    1989-01-01

    Computer programs have been written to allow the analysis of different types of eddy-current probes and their performance under different steam generator test conditions. The probe types include the differential bobbin probe, the absolute bobbin probe, the pancake probe and the reflection probe. The generator test conditions include tube supports, copper deposits, magnetite deposits, denting, wastage, pitting, cracking and IGA. These studies are based mostly on computed values, with the limited number of test specimens available used to verify the computed results. The instrument readings were computed for a complete matrix of the different test conditions, and then the test conditions determined as a function of the readings by a least-squares technique. A comparison was made of the errors in fit and instrument drift for the different probe types. The computations of the change in instrument reading due to the defects have led to an ''inversion'' technique in which the defect properties can be computed from the instrument readings. This has been done both experimentally and analytically for each of these probe types. 3 refs., 13 figs., 1 tab

  8. New eddy current testing system in steam generator tubes

    International Nuclear Information System (INIS)

    Nagata, Yasuyuki; Shimone, Junri; Maeda, Kotaro; Harada, Yutaka; Murakami, Ryuji

    2003-01-01

    Eddy Current Testing (ECT) technique is applied to PWR Steam Generator (SG) tubes during refueling outage inspection. Bobbin type probe is generally used for the inspection, but it cannot provide sufficient detectability for very tight cracks. NEL, R/D Tech (Canada) and AECL (Canada) jointly developed new ECT probe. The probe is transmit and receive type array probe. It has axial defect detection mode and circumferential defect detection mode. Its inspection speed is as fast as conventional bobbin probe, and detectability performance is same or better than performance of rotating pancake coil (RPC) probe, which is used for detailed inspection. As a tester of the new probe, we have developed new ECT tester TC7700. It is able to transmit composite wave from the 4 independent oscillators (simultaneous excitation system) compared with the conventional inspection system. As regarding for field inspection system, we have integrated Zetec (USA) probe positioner, probe pusher and R/D Tech TC7700. We are also developing new analysis software. The software has automated data screening function, which can deal with large amount of data compared with conventional bobbin probe. We plan to perform a large-scale field trial using the probe and new system in near future. (author)

  9. In-service examination of IHX tubing with eddy current NDT equipment

    International Nuclear Information System (INIS)

    Brown, R.L.

    1972-01-01

    Single and multiple frequency eddy current (ET) nondestructive testing (NDT) techniques and equipment were investigated for in-service inspection of sodium-contaminated intermediate heat exchanger (IHX) tubing. A four frequency technique, demonstrated in the laboratory, was relatively insensitive to signals caused by probe motion, tube support plates, and residual sodium on the outer surface of the tubes. No method was found to avoid the signals from residual sodium on the inside surfaces of the tube. (U.S.)

  10. Reducing leakage current in semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Bin; Matioli, Elison de Nazareth; Palacios, Tomas Apostol

    2018-03-06

    A semiconductor device includes a first region having a first semiconductor material and a second region having a second semiconductor material. The second region is formed over the first region. The semiconductor device also includes a current blocking structure formed in the first region between first and second terminals of the semiconductor device. The current blocking structure is configured to reduce current flow in the first region between the first and second terminals.

  11. Reducing Current Spread using Current Focusing in Cochlear Implant Users

    Science.gov (United States)

    Landsberger, David M.; Padilla, Monica; Srinivasan, Arthi G.

    2012-01-01

    Cochlear implant performance in difficult listening situations is limited by channel interactions. It is known that partial tripolar (PTP) stimulation reduces the spread of excitation (SOE). However, the greater the degree of current focusing, the greater the absolute current required to maintain a fixed loudness. As current increases, so does SOE. In experiment 1, the SOE for equally loud stimuli with different degrees of current focusing is measured via a forward-masking procedure. Results suggest that at a fixed loudness, some but not all patients have a reduced SOE with PTP stimulation. Therefore, it seems likely that a PTP speech processing strategy could improve spectral resolution for only those patients with a reduced SOE. In experiment 2, the ability to discriminate different levels of current focusing was measured. In experiment 3, patients subjectively scaled verbal descriptors of stimuli of various levels of current focusing. Both discrimination and scaling of verbal descriptors correlated well with SOE reduction, suggesting that either technique have the potential to be used clinically to quickly predict which patients would receive benefit from a current focusing strategy. PMID:22230370

  12. Tube-AVB gap measurements using an eddy current rotating probe

    International Nuclear Information System (INIS)

    Badson, F.; Chiron, D.; Trumpff, B.

    1988-01-01

    The wears of tubes due to flow induced vibrations have been observed after a few years of operating PWR steam generators (SG). The vibration and wear are intimately related to the gap between tubes and anti-vibration bars (AVB's) located in the bundle. The authors report the development of an eddy current (EC) method for the measurement of this gap. The method is based on using an EC probe rotating in the tube. Since for each measurement zone the tube is interacting with two AVB's the use of a rotating EC probe is necessary to perform separate and accurate measurements of each tube-AVB gap

  13. Development of a 3D electromagnetic model for eddy current tubing inspection application to steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Maillot, V. [Institut de Radioprotection et de Surete Nucleaire, IRSN, 92 - Fontenay aux Roses (France); Pichenot, G.; Premel, D.; Sollier, T. [CEA Saclay, DRT/DECS, 91 - Gif-sur-Yvette (France)

    2003-10-01

    In nuclear plants, the inspection of heat exchanger tubes is usually carried out by using eddy current nondestructive testing. A numerical model, based on a volume integral approach using the Green's dyadic formalism, has been developed, with support from the French Institute for Radiological Protection and Nuclear Safety, to predict the response of an eddy current bobbin coil to 3D flaws located in the tube's wall. With an aim of integrating this model into the NDE multi techniques platform CIVA, it has been validated with experimental data for 2D and 3D flaws. (authors)

  14. Dose reduction in CT by on-line tube current control: principles and validation on phantoms and cadavers

    International Nuclear Information System (INIS)

    Kalender, W.A.; Wolf, H.; Suess, C.; Gies, M.; Greess, H.; Bautz, W.A.

    1999-01-01

    We investigated approaches to reducing the dose in CT without impairing image quality. Dose can be reduced for non-circular object cross-sections without a significant increase in noise if X-ray tube current is reduced at angular tube positions where the X-ray attenuation by the patients is small. We investigated different schemes of current modulation during tube rotation by simulation and phantom measurements. Both pre-programmed sinusoidal modulation functions and attenuation-based on-line control of the tube current were evaluated. All relevant scan parameters were varied, including constraints such as the maximum modulation amplitude. A circular, an elliptical and two oval water phantoms were used. Results were validated on six cadavers. Dose reduction of 10-45 % was obtained both in simulations and in measurements for the different non-circular phantom geometries and current modulation algorithms without an increase in pixel noise values. On-line attenuation-based control yielded higher reductions than modulation by a sinusoidal curve. The maximal dose reduction predicted by simulations could not be achieved due to limits in the modulation amplitude. In cadaver studies, a reduction of typically 20-40 % was achieved for the body and about 10 % for the head. Variations of our technique are possible; a slight increase in nominal tube current for high-attenuation projections combined with attenuation-based current modulation still yields significant dose reduction, but also a reduction in the structured noise that may obscure diagnostic details. We conclude that a significant reduction in dose can be achieved by tube current modulation without compromising image quality. Attenuation-based on-line control and a modulation amplitude of at least 90 % should be employed. (orig.)

  15. Monte Carlo simulations to assess the effects of tube current modulation on breast dose for multidetector CT

    International Nuclear Information System (INIS)

    Angel, Erin; Yaghmai, Nazanin; Jude, Cecilia Matilda; DeMarco, John J; Cagnon, Christopher H; Goldin, Jonathan G; McNitt-Gray, Michael F; Primak, Andrew N; McCollough, Cynthia H; Stevens, Donna M; Cody, Dianna D

    2009-01-01

    Tube current modulation was designed to reduce radiation dose in CT imaging while maintaining overall image quality. This study aims to develop a method for evaluating the effects of tube current modulation (TCM) on organ dose in CT exams of actual patient anatomy. This method was validated by simulating a TCM and a fixed tube current chest CT exam on 30 voxelized patient models and estimating the radiation dose to each patient's glandular breast tissue. This new method for estimating organ dose was compared with other conventional estimates of dose reduction. Thirty detailed voxelized models of patient anatomy were created based on image data from female patients who had previously undergone clinically indicated CT scans including the chest area. As an indicator of patient size, the perimeter of the patient was measured on the image containing at least one nipple using a semi-automated technique. The breasts were contoured on each image set by a radiologist and glandular tissue was semi-automatically segmented from this region. Previously validated Monte Carlo models of two multidetector CT scanners were used, taking into account details about the source spectra, filtration, collimation and geometry of the scanner. TCM data were obtained from each patient's clinical scan and factored into the model to simulate the effects of TCM. For each patient model, two exams were simulated: a fixed tube current chest CT and a tube current modulated chest CT. X-ray photons were transported through the anatomy of the voxelized patient models, and radiation dose was tallied in the glandular breast tissue. The resulting doses from the tube current modulated simulations were compared to the results obtained from simulations performed using a fixed mA value. The average radiation dose to the glandular breast tissue from a fixed tube current scan across all patient models was 19 mGy. The average reduction in breast dose using the tube current modulated scan was 17%. Results were

  16. Noise-based tube current reduction method with iterative reconstruction for reduction of radiation exposure in coronary CT angiography

    International Nuclear Information System (INIS)

    Shen, Junlin; Du, Xiangying; Guo, Daode; Cao, Lizhen; Gao, Yan; Bai, Mei; Li, Pengyu; Liu, Jiabin; Li, Kuncheng

    2013-01-01

    Purpose: To investigate the potential of noise-based tube current reduction method with iterative reconstruction to reduce radiation exposure while achieving consistent image quality in coronary CT angiography (CCTA). Materials and methods: 294 patients underwent CCTA on a 64-detector row CT equipped with iterative reconstruction. 102 patients with fixed tube current were assigned to Group 1, which was used to establish noise-based tube current modulation formulas, where tube current was modulated by the noise of test bolus image. 192 patients with noise-based tube current were randomly assigned to Group 2 and Group 3. Filtered back projection was applied for Group 2 and iterative reconstruction for Group 3. Qualitative image quality was assessed with a 5 point score. Image noise, signal intensity, volume CT dose index, and dose-length product were measured. Results: The noise-based tube current modulation formulas were established through regression analysis using image noise measurements in Group 1. Image noise was precisely maintained at the target value of 35.00 HU with small interquartile ranges for Group 2 (34.17–35.08 HU) and Group 3 (34.34–35.03 HU), while it was from 28.41 to 36.49 HU for Group 1. All images in the three groups were acceptable for diagnosis. A relative 14% and 41% reduction in effective dose for Group 2 and Group 3 were observed compared with Group 1. Conclusion: Adequate image quality could be maintained at a desired and consistent noise level with overall 14% dose reduction using noise-based tube current reduction method. The use of iterative reconstruction further achieved approximately 40% reduction in effective dose

  17. Multifrequency Eddy current testing of heat exchange tubes with a rotating probe

    International Nuclear Information System (INIS)

    Levy, R.

    1982-01-01

    Multi-frequency eddy current analyses have been used in France industrially since 1975. In light of the experienced gained during many steam generator inspections, this technique was applied to the examination of sheet and tube heat exchangers featuring tubes in very different materials such as copper, stainless steel and titanium. The principle of multi-frequency Eddy current inspection is first reviewed, using the example of a condenser with nickel alloy tubes (Inconel, Incoloy). This is followed by the description of a specific application of this technique to a condenser with titanium tubes, analyzed with a rotating local probe [fr

  18. Modeling of tube current modulation methods in computed tomography dose calculations for adult and pregnant patients

    International Nuclear Information System (INIS)

    Caracappa, Peter F.; Xu, X. George; Gu, Jianwei

    2011-01-01

    The comparatively high dose and increasing frequency of computed tomography (CT) examinations have spurred the development of techniques for reducing radiation dose to imaging patients. Among these is the application of tube current modulation (TCM), which can be applied either longitudinally along the body or rotationally along the body, or both. Existing computational models for calculating dose from CT examinations do not include TCM techniques. Dose calculations using Monte Carlo methods have been previously prepared for constant-current rotational exposures at various positions along the body and for the principle exposure projections for several sets of computational phantoms, including adult male and female and pregnant patients. Dose calculations from CT scans with TCM are prepared by appropriately weighting the existing dose data. Longitudinal TCM doses can be obtained by weighting the dose at the z-axis scan position by the relative tube current at that position. Rotational TCM doses are weighted using the relative organ doses from the principle projections as a function of the current at the rotational angle. Significant dose reductions of 15% to 25% to fetal tissues are found from simulations of longitudinal TCM schemes to pregnant patients of different gestational ages. Weighting factors for each organ in rotational TCM schemes applied to adult male and female patients have also been found. As the application of TCM techniques becomes more prevalent, the need for including TCM in CT dose estimates will necessarily increase. (author)

  19. Garter spring location of pressure tube for PHWR using eddy current testing methods

    International Nuclear Information System (INIS)

    Lee, Y. S.; Yang, D. J.; Jeong, H. K.

    2001-01-01

    There are garter springs between pressure tube and calandria tube for PHWR. If the space of these garter springs become to be changed, the sagging of tube is caused and the contact between the pressure tube and calandria tube will cause the tube to be failed. AECL has applied the eddy current testing methods using send-receive type probe for this purpose, but this study apply eddy current testing methods using bobbin differential type probe to detection of garter spring location. And we did the computer simulation using VIC-3D code and compared it with experiments results for inspection 1 ∼ 11kHz. The results was that the garter spring signal was successfully detected for every frequency, and 5 kHz was best

  20. Dose conversion coefficients for paediatric CT examinations with automatic tube current modulation

    International Nuclear Information System (INIS)

    Schlattl, H; Zankl, M; Becker, J; Hoeschen, C

    2012-01-01

    A common dose-saving technique used in modern CT devices is automatic tube current modulation (TCM), which was originally designed to also reduce the dose in paediatric CT patients. In order to be able to deduce detailed organ doses of paediatric models, dose conversion coefficients normalized to CTDI vol for an eight-week-old baby and seven- and eight-year-old children have been computed accounting for TCM. The relative difference in organ dose conversion coefficients with and without TCM is for many organs and examinations less than 10%, but can in some cases amount up to 30%, e.g., for the thyroid in the chest CT of the seven-year-old child. Overall, the impact of TCM on the conversion coefficients increases with increasing age. Besides TCM, also the effect of collimation and tube voltage on organ dose conversion coefficients has been investigated. It could be shown that the normalization to CTDI vol leads to conversion coefficients that can in most cases be considered to be independent of collimation and tube voltage. (paper)

  1. Automation of inspection methods for eddy current testing of steam generator tubes

    International Nuclear Information System (INIS)

    Meurgey, P.; Baumaire, A.

    1990-01-01

    Inspection of all the tubes of a steam generator when the reactor is stopped is required for some of these exchangers affected by stress corrosion cracking. Characterization of each crack, in each tube is made possible by the development of software for processing the signals from an eddy current probe. The ESTELLE software allows a rapid increase of tested tubes, more than 80,000 in 1989 [fr

  2. Achieving reduced fouling of cooling water exchangers with stainless steel tubes

    International Nuclear Information System (INIS)

    Iftikhar, A.; Mir, N.

    2010-01-01

    Good performance of cooling water heat exchangers plays a vital role in the over all energy efficiency of a chemical plant. Heavy fouling on carbon steel tubes of the cooling water exchangers was causing poor performance and frequent cleaning requirement. The carbon steel tubes were replaced with stainless steel tubes. Improved performance was achieved and cleaning frequency reduced. The paper covers the details of study and methodology applied for the above changes along with summary of results. (author)

  3. The impact of the AEC mode of tube current on the dose at CT scans

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Il Bong; Dong, Kyung Rae [Dept. of Radiological Technology, Gwangju Health University, Gwangju (Korea, Republic of); Kim, Kwang Cheol [Dept. of of Nuclear Engineering, Chosun University,Gwangju (Korea, Republic of)

    2016-11-15

    In this study, the automatic exposure control (AEC) modes of tube current (SIEMENSCare Dose 4D and GE AEC mode) that CT manufacturers are using was applied to neck, chest and abdomen in order to determine the difference in the respective dose parameters (CTDIvol, DLP and mSv) resulting from the dose reduction. Equipment in use at C university adopted Care Dose 4D of Siemens and AEC mode of General Electric (GE), and the x-ray exposure conditions were adjusted to be as identical as possible between the experiments. For the assessment of the dose reduction, the differences between the doses with and without the use of the tube current AEC mode by the respective manufacturer were measured for each body part including neck, chest and abdomen of a human phantom, Rando Phantom (Art-200x, Fluke Biomedical, USA). First, the assessment of SIEMENS-Care Dose 4D yielded the following results. At the neck, the automatic exposure control resulted in a 3.3% reduction in CTDIvol and DLP, and a 3% reduction in the effective dose, mSv, compared to manual exposure control. The automatic exposure control at the chest displayed the reduction in CTDIvol and DLP by 25.5%, and in the effective dose, mSv, by 25.4% compared to the manual exposure control. In case of abdomen, CTDIvol and DLP were shown to be reduced by 16%, and the effective dose (mSv) by 16.3% under the automatic exposure control compared to the manual exposure. Second, the assessment results of GE AEC mode are as follows. The automatic exposure control at the neck resulted in a 45.1% reduction in CTDIvol and DLP, and a 44.7% reduction in the effective dose (mSv) in comparison to the manual exposure control. At the chest, the automatic exposure control displayed a 47.6% reduction in CTDIvol and DLP, and a 47.5% reduction in the effective dose, mSv, compared to the manual exposure control. At the abdomen, it was shown that CTDIvol and DLP were reduced by 26.9%, and the effective dose (mSv) by 26.8% under the automatic

  4. The impact of the AEC mode of tube current on the dose at CT scans

    International Nuclear Information System (INIS)

    Moon, Il Bong; Dong, Kyung Rae; Kim, Kwang Cheol

    2016-01-01

    In this study, the automatic exposure control (AEC) modes of tube current (SIEMENSCare Dose 4D and GE AEC mode) that CT manufacturers are using was applied to neck, chest and abdomen in order to determine the difference in the respective dose parameters (CTDIvol, DLP and mSv) resulting from the dose reduction. Equipment in use at C university adopted Care Dose 4D of Siemens and AEC mode of General Electric (GE), and the x-ray exposure conditions were adjusted to be as identical as possible between the experiments. For the assessment of the dose reduction, the differences between the doses with and without the use of the tube current AEC mode by the respective manufacturer were measured for each body part including neck, chest and abdomen of a human phantom, Rando Phantom (Art-200x, Fluke Biomedical, USA). First, the assessment of SIEMENS-Care Dose 4D yielded the following results. At the neck, the automatic exposure control resulted in a 3.3% reduction in CTDIvol and DLP, and a 3% reduction in the effective dose, mSv, compared to manual exposure control. The automatic exposure control at the chest displayed the reduction in CTDIvol and DLP by 25.5%, and in the effective dose, mSv, by 25.4% compared to the manual exposure control. In case of abdomen, CTDIvol and DLP were shown to be reduced by 16%, and the effective dose (mSv) by 16.3% under the automatic exposure control compared to the manual exposure. Second, the assessment results of GE AEC mode are as follows. The automatic exposure control at the neck resulted in a 45.1% reduction in CTDIvol and DLP, and a 44.7% reduction in the effective dose (mSv) in comparison to the manual exposure control. At the chest, the automatic exposure control displayed a 47.6% reduction in CTDIvol and DLP, and a 47.5% reduction in the effective dose, mSv, compared to the manual exposure control. At the abdomen, it was shown that CTDIvol and DLP were reduced by 26.9%, and the effective dose (mSv) by 26.8% under the automatic

  5. Eddy-current inspection of ferromagnetic tubing using pulsed magnetic saturation

    Energy Technology Data Exchange (ETDEWEB)

    Dodd, C V; Deeds, W E

    1986-07-01

    A pulsed eddy-current system has been designed and developed for nondestructive evaluation of 2.25Cr-1Mo steam generator tubing from the bore side. Since the tubing is ferromagnetic, a large current pulse is sent through a driver coil to produce magnetic saturation all the way through the tube wall. A pickup coil produces an output pulse that is dependent upon the tube properties as well as the driving pulse. The output pulse heights at selected times are used as data that are computer-correlated with calibration data taken from machined standards. Performance data, circuit diagrams, and computer programs are given for the system, which has been demonstrated to detect small flaws located near the outside of a thick ferromagnetic tube.

  6. Motor Challenge: Improving Efficiency of Tube Drawing Bench Reduces Energy Use by 34%

    International Nuclear Information System (INIS)

    Erika Ericksen

    1999-01-01

    The case study reveals how a manufacturer of high-precision, small-diameter steel tubing has reduced energy consumption and realized considerable electrical, labor, and materials cost savings with a more energy-efficient motor

  7. Evaluation of the eddy-current method for the inspection of steam generator tubing: denting

    International Nuclear Information System (INIS)

    Brown, S.D.; Flora, J.H.

    1977-01-01

    Continued evaluation of existing eddy-current in-service inspection (ISI) methods for steam generator tubing has emphasized the effects of denting. Denting is a circumferential deformation of the tube in the support region as a result of the formation of a magnetite, Fe 3 O 4 , corrosion product on the carbon steel tube support plate in the crevice between the support plate and the tube wall. The effects of denting on eddy current inspection are twofold: (1) The detection and measurement of defects in the dented region is hampered by the distortion of the eddy-current response signals caused by the dents and (2) large dents may prevent the passage of high fill factor probes forcing the inspection teams to use a smaller probe in undented regions. Unless appropriate measures are taken, less reliable detection of defects and estimation of their depth can result. The report presents an experimental evaluation of existing eddy-current ISI methods when used to inspect dented regions. Tubes were mechanically dented to simulate various degrees of service induced denting. These tubes were then inserted in carbon steel tube support plates and the crevice region between the support plate and tube was subsequently packed with powdered magnetite. Diametral dent sizes considered during this program varied between 1 and 10 mils. Eddy-current signal patterns and strip chart recordings were obtained using a variety of test parameters, such as frequency, phase rotation and coil configuration, on tube samples containing various degrees of denting and with several types of defects in the dented system

  8. Achieving consistent image quality and overall radiation dose reduction for coronary CT angiography with body mass index-dependent tube voltage and tube current selection

    International Nuclear Information System (INIS)

    Wang, G.; Gao, J.; Zhao, S.; Sun, X.; Chen, X.; Cui, X.

    2014-01-01

    Aim: To develop a quantitative body mass index (BMI)-dependent tube voltage and tube current selection method for obtaining consistent image quality and overall dose reduction in computed tomography coronary angiography (CTCA). Methods and materials: The images of 190 consecutive patients (group A) who underwent CTCA with fixed protocols (100 kV/193 mAs for 100 patients with a BMI of <27 and 120 kV/175 mAs for 90 patients with a BMI of >27) were retrospectively analysed and reconstructed with an adaptive statistical iterative reconstruction (ASIR) algorithm at 50% blending. Image noise was measured and the relationship to BMI was studied to establish BMI-dependent tube current for obtaining CTCA images with user-specified image noise. One hundred additional cardiac patients (group B) were examined using prospective triggering with the BMI-dependent tube voltage/current. CTCA image-quality score, image noise, and effective dose from groups B and C (subgroup of A of 100 patients examined with prospective triggering only) were obtained and compared. Results: There was a linear relationship between image noise and BMI in group A. Using a BMI-dependent tube current in group B, an average CTCA image noise of 27.7 HU (target 28 HU) and 31.7 HU (target 33 HU) was obtained for the subgroups of patients with BMIs of >27 and of <27, respectively, and was independent of patient BMI. There was no difference between image-quality scores between groups B and C (4.52 versus 4.60, p > 0.05). The average effective dose for group B (2.56 mSv) was 42% lower than group C (4.38 mSv; p < 0.01). Conclusion: BMI-dependent tube voltage/current selection in CTCA provides an individualized protocol that generates consistent image quality and helps to reduce overall patient radiation dose. - Highlights: • BMI-dependent kVp and mA selection method may be established in CCTA. • BMI-dependent kVp and mA enables consistent CCTA image quality. • Overall dose reduction of 40% can

  9. Evaluation and field validation of Eddy-Current array probes for steam generator tube inspection

    International Nuclear Information System (INIS)

    Dodd, C.V.; Pate, J.R.

    1996-07-01

    The objective of the Improved Eddy-Current ISI for Steam Generator Tubing program is to upgrade and validate eddy-current inspections, including probes, instrumentation, and data processing techniques for inservice inspection of new, used, and repaired steam generator tubes; to improve defect detection, classification, and characterization as affected by diameter and thickness variations, denting, probe wobble, tube sheet, tube supports, copper and sludge deposits, even when defect types and other variables occur in combination; to transfer this advanced technology to NRC's mobile NDE laboratory and staff. This report describes the design of specialized high-speed 16-coil eddy-current array probes. Both pancake and reflection coils are considered. Test results from inspections using the probes in working steam generators are given. Computer programs developed for probe calculations are also supplied

  10. Duality of the magnetic flux tube and electric current descriptions magnetospheric plasma and energy flow

    International Nuclear Information System (INIS)

    Atkinson, G.

    1981-01-01

    The duality between electric current and magnetic flux tubes is outlined for the magnetosphere. Magnetic flux tubes are regarded as fluid elements subjected to various stresses. Current closure then becomes the dual of stress balance, and Poynting vector energy flow a dual of J x E dissipation. The stresses acting on a flux tube are magnetic stresses, which correspond to currents at a distance, and plasma stresses, which correspond to local currents. The duality between current and stress is traced for ionospheric ion drag forces, solar wind stresses at the magnetopause, inertial effects, and the effects of energetic plasma on flux tubes. The stress balance and dual current systems are outlined for idealized magnetospheres of increasing complexity. For a simple magnetosphere with no convective flow, the balance stresses are solar wind pressure and neutral sheet plasma pressure. The corresponding current systems are the Chapman-Ferraro magnetopause currents and the magetotail current system. The introduction of convective flow introduces further stresses: ionospheric ion drag. Alfven layer shielding, and an imbalance in day-night magnetic stresses due to transport of flux tubes to the nightside by the solar wind. These stresses balance, and hence the corresponding additional currents (the ionospheric Pedersen current and the electrojets, the partial ring current, and two other current systems from the magnetopause and tail) must form a closed current system and do so by the region I and II field-aligned currents of Iijima and Potemra. The energy flow in the above models is described in terms of both Poynting vectors and the above current systems. Temporal variations examined are (1) an increase in dayside merging and/or nightside reconnection, (2) an increase in the energy density of plasma in the plasma sheet, (3) an increase in ionospheric conductivity, and (4) an increase in solar wind pressure

  11. Scale Thickness Measurement of Steam Generator Tubing Using Eddy Current Signal of Bobbin Coil

    International Nuclear Information System (INIS)

    Kim, Chang Soo; Um, Ki Soo; Kim, Jae Dong

    2012-01-01

    Steam generator is one of the major components of nuclear power plant and steam generator tubes are the pressure boundary between primary and secondary side, which makes them critical for nuclear safety. As the operating time of nuclear power plant increases, not only damage mechanisms but also scaled deposits on steam generator tubes are known to be problematic causing tube support flow hole blockage and heat fouling. The ability to assess the extent and location of scaled deposits on tubes became essential for management and maintenance of steam generator and eddy current bobbin data can be utilized to measure thickness of scale on tubes. In this paper, tube reference standards with various thickness of scaled deposit has been set up to provide information about the overall deposit condition of steam generator tubes, providing essential tool for steam generator management and maintenance to predict and prevent future damages. Also, methodology to automatically measure scale thickness on tubes has been developed and applied to field data to estimate overall scale amount.

  12. Guiding effect of bent macroscopic quartz tube for high current electron beam

    International Nuclear Information System (INIS)

    Zhang Mingwu; Chen Jing; Wu Yehong; Yang Bian; Wang Wei; Xue Yingli; Yu Deyang; Cai Xiaohong

    2012-01-01

    By using an incident electron beam with the high current and high energy, the guiding effect of the bent macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing, the electron transmitted fraction increases, but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents, the process of guiding electrons is essentially different from that of guiding highly charged ions, the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube, rather than self-organized charging effect on the surface of inner wall of quartz tube. (authors)

  13. Automatic tube-current modulation in CT - A comparison between different solutions

    International Nuclear Information System (INIS)

    Althen, J. N.

    2005-01-01

    In this study, tube-current modulation systems on two different CT equipments have been evaluated: Care Dose from Siemens and Auto mA from GE Medical Systems. Care Dose modulates the tube current in the xy-plane during rotation whereas Auto mA modulates the tube current in the z-direction. xy-Plane modulation was investigated by using an elliptic Poly-methylmethacrylate phantom and a CTDI-ion chamber. To investigate modulation in the z-direction, an anthropomorphic dosimetry phantom (Atom) was used. Tests performed with and without tube-current modulation were compared with respect to absorbed dose and image quality. In the anthropomorphic phantom measurements, the dose savings were 15% using Care Dose and the photon starvation artefacts were negligible. Using Auto mA the absorbed dose depends on the chosen noise level. Image noise becomes more constant throughout the patient but photon starvation artefacts remain. We conclude that the two tube-current modulation techniques show different dose advantages and image quality artefacts. (authors)

  14. Eddy current technology for heat exchanger and steam generator tube inspection

    Energy Technology Data Exchange (ETDEWEB)

    Obrutsky, L.; Lepine, B.; Lu, J.; Cassidy, R.; Carter, J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2004-07-01

    A variety of degradation modes can affect the integrity of both heat exchanger (HX) and balance of plant tubing, resulting in expensive repairs, tube plugging or replacement of tube bundles. One key component for ensuring tube integrity is inspection and monitoring for detection and characterization of the degradation. In-service inspection of HX and balance of plant tubing is usually carried out using eddy current (EC) bobbin coils, which are adequate for the detection of volumetric degradations. However, detection and quantification of additional modes of degradation such as pitting, intergranular attack (IGA), axial cracking and circumferential cracking require specialized probes. The need for timely, reliable detection and characterization of these modes of degradation is especially critical in Nuclear Generating Stations. Transmit-receive single-pass array probes, developed by AECL, offer high defect detectability in conjunction with fast and reliable inspection capabilities. They have strong directional properties, permitting probe optimization for circumferential or axial crack detection. Compared to impedance probes, they offer improved performance in the presence of variable lift-off. This EC technology can help resolve critical detection issues at susceptible areas, such as the rolled-joint transitions at the tubesheet, U-bends and tube-support intersections. This paper provides an overview of the operating principles and the capabilities of advanced ET inspection technology available for HX tube inspection. Examples of recent application of this technology in Nuclear Generating Stations (NGSs) are discussed. (author)

  15. Eddy current technology for heat exchanger and steam generator tube inspection

    International Nuclear Information System (INIS)

    Obrutsky, L.; Lepine, B.; Lu, J.; Cassidy, R.; Carter, J.

    2004-01-01

    A variety of degradation modes can affect the integrity of both heat exchanger (HX) and balance of plant tubing, resulting in expensive repairs, tube plugging or replacement of tube bundles. One key component for ensuring tube integrity is inspection and monitoring for detection and characterization of the degradation. In-service inspection of HX and balance of plant tubing is usually carried out using eddy current (EC) bobbin coils, which are adequate for the detection of volumetric degradations. However, detection and quantification of additional modes of degradation such as pitting, intergranular attack (IGA), axial cracking and circumferential cracking require specialized probes. The need for timely, reliable detection and characterization of these modes of degradation is especially critical in Nuclear Generating Stations. Transmit-receive single-pass array probes, developed by AECL, offer high defect detectability in conjunction with fast and reliable inspection capabilities. They have strong directional properties, permitting probe optimization for circumferential or axial crack detection. Compared to impedance probes, they offer improved performance in the presence of variable lift-off. This EC technology can help resolve critical detection issues at susceptible areas, such as the rolled-joint transitions at the tubesheet, U-bends and tube-support intersections. This paper provides an overview of the operating principles and the capabilities of advanced ET inspection technology available for HX tube inspection. Examples of recent application of this technology in Nuclear Generating Stations (NGSs) are discussed. (author)

  16. Optimum Frequency for Eddy Current Testing Method of SMART SG tubes

    International Nuclear Information System (INIS)

    Lee, Yoon Sang; Jung, Hyun Kyu; Choung, Yun Hang

    2009-01-01

    The SMART SG tubes will be made of Alloy 690. The outside diameter will be 17 mm and the thickness will be 2.5 mm. They will be assembled helically around, and their innermost diameter will be about 600 mm and the total length will be about 32 meters. For safety, SMART SG tubes are designed for use with thick tubes such as 2.5 mm thickness compared to about 1 mm thickness of normal Korean standard pressurized water reactor tubes. Due to using thick tubes such as 2.5 mm varieties, it was doubted that the Eddy Current Testing Method (ECT) would be a feasible method. Therefore we are trying to simulate the bobbin probe signal for SMART SG tubes and comparing it to PWR SG ECT probe signal using VIM software, checking for the applicability of ECT. Also we are trying to compare the ECT signal of 2.5 mm thick stainless tubes to check if they are possible substitute material

  17. Evaluation of the inner wall axial cracks of steam generator tubes by eddy current test

    International Nuclear Information System (INIS)

    Hur, Do Haeng; Choi, Myung Sik; Lee, Doek Hyun; Han, Jung Ho

    2001-01-01

    For the enhancement of ECT reliability on the primary water stress corrosion cracks of nuclear steam generator tubes, it is important to comprehend the signal characteristics on crack morphology and to select an appropriate probe type. In this paper, the sizing accuracy and the detectability for the inner wall axial cracks of tubes were quantitatively evaluated using the electric discharge machined notches and the corrosion cracks which were developed on the operating steam generator tubes. The difference of eddy current signal characteristics between pancake and axial coil were also investigated. The results obtained from this study provide a useful information for more precise evaluation on the inner wall axial cracks of steam generator tubes.

  18. Evaluation of Eddy Current Signals from the Inner Wall Axial Cracks of Steam Generator Tubes

    International Nuclear Information System (INIS)

    Choi, Myung Sik; Hur, Do Haeng; Lee, Doek Hyun; Han, Jung Ho; Park, Jung Am

    2001-01-01

    For the enhancement of ECT reliability on the primary water stress corrosion cracks of nuclear steam generator tubes, of which the occurrence is on the increase, it is important to comprehend the signal characteristics on crack morphology and to select an appropriate probe type. In this paper, the sizing accuracy and the detectability for the inner wall axial cracks of tubes were quantitatively evaluated using the following specimens: the electric discharge machined notches and the corrosion cracks which were developed on the operating steam generator tubes. The difference of eddy current signal characteristics between pancake and axial coil were also Investigated. The results obtained from this study provide a useful information for more precise evaluation on the inner wall axial tracks oi steam generator tubes

  19. NASA Lewis Stirling SPRE testing and analysis with reduced number of cooler tubes

    International Nuclear Information System (INIS)

    Wong, W.A.; Cairelli, J.E.; Swec, D.M.; Doeberling, T.J.; Lakatos, T.F.; Madi, F.J.

    1994-01-01

    Free-piston Stirling power converters are a candidate for high capacity space power applications. The Space Power Research Engine (SPRE), a free-piston Stirling engine coupled with a linear alternator, is being tested at the NASA Lewis Research Center in support of the Civil Space Technology Initiative. The SPRE is used as a test bed for evaluating converter modifications which have the potential to improve converter performance and for validating computer code predictions. Reducing the number of cooler tubes on the SPRE has been identified as a modification with the potential to significantly improve power and efficiency. This paper describes experimental tests designed to investigate the effects of reducing the number of cooler tubes on converter power, efficiency and dynamics. Presented are test results from the converter operating with a reduced number of cooler tubes and comparisons between this data and both baseline test data and computer code predictions

  20. Eddy-current tests on operational evaluation of steam generator tubes in nuclear power plants

    International Nuclear Information System (INIS)

    Lopez, Luiz Antonio Negro Martin; Ting, Daniel Kao Sun

    2000-01-01

    This paper presents a worldwide research on the technical and economical impacts due to failure in tube bundles of nuclear power plant steam generators. An Eddy current non destructive test using Foucault currents for the inspection and failure detection on the tubes, and also the main type of defects. The paper also presents the signals generated by a Zetec MIZ-40 test equipment. This paper also presents a brief description of an automatic system for data analysis which is under development by using a fuzzy logic and artificial intelligence

  1. Regression analysis of pulsed eddy current signals for inspection of steam generator tube support structures

    International Nuclear Information System (INIS)

    Buck, J.; Underhill, P.R.; Mokros, S.G.; Morelli, J.; Krause, T.W.; Babbar, V.K.; Lepine, B.

    2015-01-01

    Nuclear steam generator (SG) support structure degradation and fouling can result in damage to SG tubes and loss of SG efficiency. Conventional eddy current technology is extensively used to detect cracks, frets at supports and other flaws, but has limited capabilities in the presence of multiple degradation modes or fouling. Pulsed eddy current (PEC) combined with principal components analysis (PCA) and multiple linear regression models was examined for the inspection of support structure degradation and SG tube off-centering with the goal of extending results to include additional degradation modes. (author)

  2. Signal Characteristics of Eddy Current Test for Intergranular Attack of Steam Generator Tubes

    International Nuclear Information System (INIS)

    Choi, Myung Sik; Lee, Deok Hyun; Han, Jung Ho; Hur, Do Haeng; Cho, Se Gon; Yim, Chang Jae

    2002-01-01

    Because intergranular attack (IGA), one of the localized corrosion forms occurring on steam generator tubes, can not be fabricated by an electric discharge machining method, there are few data for the eddy current test (ECT) characteristics of IGA. In this paper, the characteristics of eddy current signals are evaluated using nonexpanded tubes with IGA defects formed in 0.1 M sodium tetrathionate solution at 40 .deg. C. The detectability and sizing accuracy of IGA were discussed in terms of the coil type and frequency of the ECT probes

  3. Optimization of recommendations for abdomen computerized tomography based on reconstruction filters, voltage and tube current

    International Nuclear Information System (INIS)

    Silveira, Vinicius da Costa

    2015-01-01

    The use of computed tomography has increased significantly over the past decades. In Brazil the use increased more than twofold from 2008 to 2014, in the meantime the abdomen procedures have tripled. The high frequency of this procedure combined by the increasing collective radiation dose in medical exposures, has resulted development tools to maximize the benefit in CT images. This work aimed to establish protocols optimized in abdominal CT through acquisitions parameters and reconstructions techniques based on filters kernels. A sample of patients undergoing abdominal CT in a diagnostic center of Rio de Janeiro was assessed. Had been collected patients information and acquisitions parameters. The phantoms CT image acquisitions were performed by using different voltage values by adjusting the tube current (mAs) to obtain the same value from CTDI vol patients with normal BMI. Afterwards, the CTDIvol values were reduced by 30%, 50% and 60%. All images were reconstructed with low-contrast filters (A) and standard filters (B). The CTDIvol values for patients with normal BMI were 7% higher than in patients with underweight BMI and 30%, 50% and 60% lower than the overweight, obese I and III patients, respectively. The evaluations of image quality showed that variation of the current (mA) and the reconstruction filters did not affect the Hounsfield values. When the contrast-to-noise ratio (CNR) was normalized to CTDIvol, the protocols acquired with 60% reduction of CTDIvol with 140 kV and 80 kV showed CNR 6% lower than the routine. Modifications of the acquisition parameters did not affect spatial resolution, but the post-processing with B filters reduced the spatial frequency by 16%. With reduced the dose of 30%, lesions in the spleen had the CNR higher than 10% routine protocols with 140 kV acquired and post-processed to filter A. The image post-processing with a filter A with a 80kV voltage provided CNR values equal to the routine for the liver lesions with a 30

  4. Evaluation of the eddy-current method of inspecting steam generator tubing

    International Nuclear Information System (INIS)

    Flora, J.H.; Brown, S.D.; Weeks, J.R.

    1976-01-01

    The objective of this project has been to evaluate the eddy-current method of inspecting steam generator tubing by conducting a series of laboratory experiments with conventional eddy-current equipment. The experiments have involved obtaining eddy-current measurements on samples of 7/8-inch OD Inconel-600 tubing provided by the Westinghouse Nuclear Energy Systems Division. A variety of machined defects and some chemically induced flaws, such as stress corrosion cracks were fabricated in the tubing. Statistical evaluation of the data was employed to estimate the error encountered in measuring corrosion defects of various depths. It appears that the eddy-current technique can provide a reasonable measure of defect depth under certain conditions. On the other hand, the evaluation indicates that it is difficult to determine the depth of certain types of flaws with reliability and precision. Furthermore, although some defects as shallow as 10 percent of the tube wall could be detected, it was not possible to detect other types of flaws that were less than 40 percent deep even when the tube supports were not near the defects. The difficulty in detecting small volume flaws is attributed to low signal-to-noise ratio. Noise is a result of unwanted signals from test variables, such as wobble and variations in tube properties. The error in measurement of certain types of larger defects is associatedin part with test variables and also with the effects that the geometry of the defect has on the eddy-current signal patterns. The distortions in signal patterns caused by gradual wastage type defects and the poor reproducibility of signal patterns obtained from notches that represent stress corrosion cracks are described. Some developments that will rectify these detection and depth measurement problems are discussed

  5. Assessment of an organ‐based tube current modulation in thoracic computed tomography

    Science.gov (United States)

    Sugai, Mai; Toyoda, Asami; Koshida, Haruka; Sakuta, Keita; Takata, Tadanori; Koshida, Kichiro; Iida, Hiroji; Matsui, Osamu

    2012-01-01

    Recently, specific computed tomography (CT) scanners have been equipped with organ‐based tube current modulation (TCM) technology. It is possible that organ‐based TCM will replace the conventional dose‐reduction technique of reducing the effective milliampere‐second. The aim of this study was to determine if organ‐based TCM could reduce radiation exposure to the breasts without compromising the image uniformity and beam hardening effect in thoracic CT examinations. Breast and skin radiation doses and the absorbed radiation dose distribution within a single section were measured with an anthropomorphic phantom and radiophotoluminescent glass dosimeters using four approaches to thoracic CT (reference, organ‐based TCM, copper shielding, and the combination of the above two techniques, hereafter referred to as the combination technique). The CT value and noise level were measured using the same calibration phantom. Organ‐based TCM and copper shielding reduced radiation doses to the breast by 23.7% and 21.8%, respectively. However, the CT value increased, especially in the anterior region, using copper shielding. In contrast, the CT value and noise level barely increased using organ‐based TCM. The combination technique reduced the radiation dose to the breast by 38.2%, but greatly increased the absorbed radiation dose from the central to the posterior regions. Moreover, the CT value increased in the anterior region and the noise level increased by more than 10% in the entire region. Therefore, organ‐based TCM can reduce radiation doses to breasts with only small increases in noise levels, making it preferable for specific groups of patients, such as children and young women. PACS numbers: 87.53.Bn; 87.57.Q‐; 87.57.qp PMID:22402390

  6. Assessment of an organ-based tube current modulation in thoracic computed tomography.

    Science.gov (United States)

    Matsubara, Kosuke; Sugai, Mai; Toyoda, Asami; Koshida, Haruka; Sakuta, Keita; Takata, Tadanori; Koshida, Kichiro; Iida, Hiroji; Matsui, Osamu

    2012-03-08

    Recently, specific computed tomography (CT) scanners have been equipped with organ-based tube current modulation (TCM) technology. It is possible that organ-based TCM will replace the conventional dose-reduction technique of reducing the effective milliampere-second. The aim of this study was to determine if organ-based TCM could reduce radiation exposure to the breasts without compromising the image uniformity and beam hardening effect in thoracic CT examinations. Breast and skin radiation doses and the absorbed radiation dose distribution within a single section were measured with an anthropomorphic phantom and radiophotoluminescent glass dosimeters using four approaches to thoracic CT (reference, organ-based TCM, copper shielding, and the combination of the above two techniques, hereafter referred to as the combination technique). The CT value and noise level were measured using the same calibration phantom. Organ-based TCM and copper shielding reduced radiation doses to the breast by 23.7% and 21.8%, respectively. However, the CT value increased, especially in the anterior region, using copper shielding. In contrast, the CT value and noise level barely increased using organ-based TCM. The combination technique reduced the radiation dose to the breast by 38.2%, but greatly increased the absorbed radiation dose from the central to the posterior regions. Moreover, the CT value increased in the anterior region and the noise level increased by more than 10% in the entire region. Therefore, organ-based TCM can reduce radiation doses to breasts with only small increases in noise levels, making it preferable for specific groups of patients, such as children and young women.

  7. Diagnostic of corrosion defects in steam generator tubes using advanced signal processing from Eddy current testing

    International Nuclear Information System (INIS)

    Formigoni, Andre L.; Lopez, Luiz A.N.M.; Ting, Daniel K.S.

    2009-01-01

    Recently, the Brazilian Angra I PWR nuclear power plant went into a programmed shutdown for substitution of its Steam Generator (SG) which life was shortened due to stress corrosion in its tubes. The total cost of investment were around R$724 million. The signals generated during an Eddy-current Testing (ECT) inspection in SG tubes of nuclear plant allows for the localization and dimensioning of defects in the tubes. The defects related with corrosion generate complex signals that are difficult to analyze and are the most common cause in SG replacement in nuclear power plants around the world. The objective of this paper is the development of a methodology that allows for the characterization of corrosion signals by ECT inspections applied in the heat exchangers tubes of SG of a nuclear power plant. In this present work, the aim is to investigate distributed type defects by inducing controlled corrosion in sample tubes of different materials The ECT signals obtained from these samples tubes with corrosion implanted, will be analyzed using Zetec ECT equipment, the MIZ-17ET and its probes. The data acquisition will use a NI PC A/D CARD 700 card and the LabVIEW program. Subsequently, we will apply mathematical tools for signal processing like time windowed Fast Fourier transforms and Wavelets transforms, in MATLAB platform, which will allow effectiveness to remove the noises and to extract representative characteristics for the defect being analyzed. Previously obtained results as well as the proposal for the future work will be presented. (author)

  8. Computer modelling of eddy current probes for ISI of pressure tube/calandria tube assemblies in PHWRs

    International Nuclear Information System (INIS)

    Rao, B.P.C.; Shyamsunder, M.T.; Bhattacharya, D.K.; Raj, Baldev

    1992-01-01

    Non-destructive Evaluation (NDE) plays a major role in ensuring the safe and reliable operation of PHWRs which are the mainstay of India's nuclear power programme. An important in-service inspection (ISI) requirement in these reactors is carried out through Eddy Current Testing (ECT) of the pressure tube (PT)/calandria tube (CT) assemblies. The material of construction of these assemblies is zircaloy-2. The two main objectives of this ISI are the detection of garter spring between CT and PT and the profiling of gap between CT and PT. The paper discusses the work carried out at the authors' laboratory on the development of ECT probes for ISI of PT/CT assemblies. Emphasis has been given on the work done on the design and optimisation of the probes using computer modeling. A 2-D finite element code has been developed for this purpose. The code is developed around a diffusion equation which can be derived from Maxwell's equations governing the electromagnetic phenomenon. An axisymmetry has been considered, since the probes are bobbin type. Results of impedance plane outputs obtained by modelling and those by experiments using actual probes have shown good matching. Salient features of an indigenously developed interactive PC based data acquisition, analysis and retrieval system to cater to ISI of PC/CT assemblies are described. (author). 10 refs., 7 figs

  9. TU-EF-204-07: Add Tube Current Modulation to a Low Dose Simulation Tool for CT Systems

    International Nuclear Information System (INIS)

    Ding, Y.; Wen, G.; Brown, K.; Klahr, P.; Dhanantwari, A.

    2015-01-01

    Purpose: We extended the capabilities of a low dose simulation tool to model Tube-Current Modulation (TCM). TCM is widely used in clinical practice to reduce radiation dose in CT scans. We expect the tool to be valuable for various clinical applications (e.g., optimize protocols, compare reconstruction techniques and evaluate TCM methods). Methods: The tube current is input as a function of z location, instead of a fixed value. Starting from the line integrals of a scan, a new Poisson noise realization at a lower dose is generated for each view. To validate the new functionality, we compared simulated scans with real scans in image space. Results: First we assessed noise in the difference between the low-dose simulations and the original high-dose scan. When the simulated tube current is a step function of z location, the noise at each segment matches the noise of 3 separate constant-tube-current-simulations. Secondly, with a phantom that forces TCM, we compared a low-dose simulation with an equivalent real low-dose scan. The mean CT number of the simulated scan and the real low-dose scan were 137.7±0.6 and 137.8±0.5 respectively. Furthermore, with 240 ROIs, the noise of the simulated scan and the real low-dose scan were 24.03±0.45 and 23.99±0.43 respectively, and they were not statistically different (2-sample t-test, p-value=0.28). The facts that the noise reflected the trend of the TCM curve, and that the absolute noise measurements were not statistically different validated the TCM function. Conclusion: We successfully added tube-current modulation functionality in an existing low dose simulation tool. We demonstrated that the noise reflected an input tube-current modulation curve. In addition, we verified that the noise and mean CT number of our simulation agreed with a real low dose scan. The authors are all employees of Philips. Yijun Ding is also supported by NIBIB P41EB002035 and NIBIB R01EB000803

  10. The control of stainless steel tubes and wires of small diameter by the Eddy current method

    International Nuclear Information System (INIS)

    Stossel, A.; Gallet, G.

    1978-01-01

    Stainless steel tubes and wires with an outer diameter greater than 1 mm were studied by Eddy currents. The sensor characteristics and the detection of defects in function of frequency are presented together with the results obtained in the detection of dimensional and metallurgical defects [fr

  11. EXTRACSION: a system for automatic Eddy Current diagnosis of steam generator tubes in nuclear power plants

    International Nuclear Information System (INIS)

    Georgel, B.; Zorgati, R.

    1992-01-01

    Improving speed and quality of Eddy Current non-destructive testing of steam generator tubes leads to automation of all process that contribute to diagnosis. This paper describes how signal processing, pattern recognition and artificial and artificial intelligence are used to build a software package that is able to automatically provide an efficient diagnosis. (author)

  12. Extraction: a system for automatic eddy current diagnosis of steam generator tubes in nuclear power plants

    International Nuclear Information System (INIS)

    Georgel, B.; Zorgati, R.

    1994-01-01

    Improving speed and quality of Eddy Current non-destructive testing of steam generator tubes leads to automatize all processes that contribute to diagnosis. This paper describes how we use signal processing, pattern recognition and artificial intelligence to build a software package that is able to automatically provide an efficient diagnosis. (authors). 2 figs., 5 refs

  13. A Study of Frequency Mixing Approaches for Eddy Current Testing of Steam Generator Tubes

    International Nuclear Information System (INIS)

    Jung, Hee Jun; Song, Sung Jin; Kim, Chang Hwan; Kim, Dae Kwang

    2009-01-01

    The multifrequency eddy current testing(ECT) have been proposed various frequency mixing algorithms. In this study, we compare these approaches to frequency mixing of ECT signals from steam generator tubes; time-domain optimization, discrete cosine transform-domain optimization. Specifically, in this study, two different frequency mixing algorithms, a time-domain optimization method and a discrete cosine transform(DCT) optimization method, are investigated using the experimental signals captured from the ASME standard tube. The DCT domain optimization method is computationally fast but produces larger amount of residue.

  14. Influence of sodium deposits in steam generator tubes on remote field eddy current signals

    Energy Technology Data Exchange (ETDEWEB)

    Thirunavukkarasu, S. [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Rao, B.P.C. [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)], E-mail: bpcrao@igcar.gov.in; Vaidyanathan, S.; Jayakumar, T.; Raj, Baldev [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

    2008-04-15

    The presence of sodium deposits in defective regions of steam generator (SG) tubes of fast-breeder reactors is expected to influence the remote field eddy current (RFEC) signals. By exposing five SG tubes having uniform wall loss grooves to a sodium environment in a specially designed test vessel, changes in the shape of RFEC signals were observed and it was possible to approximate the volume of sodium deposited in defects. An invariant signal parameter was determined for quantitative characterization of defects despite the presence of sodium in the defects.

  15. Recent Advances in Simulation of Eddy Current Testing of Tubes and Experimental Validations

    Science.gov (United States)

    Reboud, C.; Prémel, D.; Lesselier, D.; Bisiaux, B.

    2007-03-01

    Eddy current testing (ECT) is widely used in iron and steel industry for the inspection of tubes during manufacturing. A collaboration between CEA and the Vallourec Research Center led to the development of new numerical functionalities dedicated to the simulation of ECT of non-magnetic tubes by external probes. The achievement of experimental validations led us to the integration of these models into the CIVA platform. Modeling approach and validation results are discussed here. A new numerical scheme is also proposed in order to improve the accuracy of the model.

  16. Field-aligned current density versus electric potential characteristics for magnetospheric flux tubes

    International Nuclear Information System (INIS)

    Lemaire, J.; Scherer, M.

    1983-01-01

    The field-aligned current density (Jsub(tot)) is a non-linear function of the applied potential difference (phi) between the ionosphere and the magnetosphere. This nonlinear function has been calculated for plasma boundary conditions typical in a dayside cusp magnetic flux tube. The J-characteristic of such a flux tube changes when the temperatures of the warm magnetospheric electrons and of the cold ionospheric electrons are modified; it changes also when the relative density of the warm plasma is modified; the presence of trapped secondary electrons changes also the J-characteristic. The partial currents contributed by the warm and cold electrons, and by warm and cold ions are illustrated. The dynamic characteristic of an electric circuit depends on the static characteristic of each component of the sytem: i.e. the resistive ionosphere, the return current region, and the region of particle precipitation whose field-aligned current/voltage characteristics have been studied in this article

  17. Eddy-current testing of nuclear fuel cladding tubes using tilted encircling coil system, 1

    International Nuclear Information System (INIS)

    Yin, Renzhong; Sekine, Kazuyoshi; Shimizu, Hisaji; Tsukui, Kazushige; Urata, Megumu.

    1989-01-01

    The eddy current testing method with external encircling-coils has been widely used as a standard technique for inspection of defects in irradiated zircaloy cladding tubes. In this inspection, the systematic procedure to reliably characterize defects is required. This paper describes the newly developed external tilted encircling-coil system, in which the coil axis is inclined by an angle α to the sample tube axis, for reliable determination of the sort, location and size of defects. As the results of experimental work concerning some kinds of artificial defects in zircaloy cladding tubes using newly designed tilted coil system, an adaptable general-procedure for characterization of defects has been proposed. Furthermore, it has been confirmed that in the case of smaller tilt angles of coil, the signal-to noise ratio for defect response in this coil system is approximately equal to that of ordinary encircling coil system. (author)

  18. Current-driven vortex domain wall motion in wire-tube nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Espejo, A. P. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); Institute of Nanostructure and Solid State Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Vidal-Silva, N. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); López-López, J. A. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Goerlitz, D.; Nielsch, K. [Institute of Nanostructure and Solid State Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Av. Ecuador 3493, 9170124 Santiago (Chile)

    2015-03-30

    We have investigated the current-driven domain wall motion in nanostructures comprised of a pair of nanotube and nanowire segments. Under certain values of external magnetic fields, it is possible to pin a vortex domain wall in the transition zone between the wire and tube segments. We explored the behavior of this domain wall under the action of an electron flow applied in the opposite direction to the magnetic field. Thus, for a fixed magnetic field, it is possible to release a domain wall pinned simply by increasing the intensity of the current density, or conversely, for a fixed current density, it is possible to release the domain wall simply decreasing the magnetic external field. When the domain wall remains pinned due to the competition between the current density and the magnetic external field, it exhibits a oscillation frequency close to 8 GHz. The amplitude of the oscillations increases with the current density and decreases over time. On the other hand, when the domain wall is released and propagated through the tube segment, this shows the standard separation between a steady and a precessional regime. The ability to pin and release a domain wall by varying the geometric parameters, the current density, or the magnetic field transforms these wire-tube nanostructures in an interesting alternative as an on/off switch nano-transistor.

  19. Enhanced methods for operating refueling station tube-trailers to reduce refueling cost

    Science.gov (United States)

    Elgowainy, Amgad; Reddi, Krishna

    2017-08-22

    A method and apparatus are provided for operating a refueling station including source tube-trailers and at least one compressor to reduce refueling cost. The refueling station includes a gaseous fuel supply source including a plurality of tanks on a tube trailer coupled to a first control unit, and high pressure buffer storage having predefined capacity coupled to a second control unit and the first tanks by a pressure control valve and the first control unit, and at least one compressor. The refueling station is operated at different modes depending on a state of the refueling station at the beginning of each operational mode. The refueling system is assessed at the end of each operational mode to identify the state of the system and select a next mode of operation. The operational modes include consolidating hydrogen, or any gaseous fuel, within the tubes mounted on the trailer.

  20. Eddy Currents Inspection of CANDU Steam Generator Tubes using Zetec's ZR-1 Robot. Experience in Romania

    International Nuclear Information System (INIS)

    Scott Hower; Luiza Vladu; Adrian Nichisov; Mihai Cretu

    2006-01-01

    Full text of publication follows: The commercial operation of Unit 1 of Cernavoda NPP started on 2 December, 1996. The unit's reactor type is PHWR-CANDU 6 (electrical capacity 706 MWe), using natural uranium. The nuclear fuel is manufactured in Romania. The Cernavoda nuclear power plant has four CANDU - design steam generators that have been in service since 1996. The paper introduces the new ZR-1 Robot System for Inspection and Maintenance/Repair from Zetec that combines the newest state-of-the-art robotics technology with Zetec experience - based innovation to address the needs for inspection and repair of steam generators. The multipurpose ZR-1 can be easily installed to perform the necessary eddy current inspection and remain installed ready for follow-up maintenance and repair. It has superior technical performances and a modular three axis motion of arm that enables 100% coverage of tube sheet. Automated, repeatable, and precise positioning of tool heads ensures accurate delivery and reducing costly rework and reduces inspection time by 30%. The modular, light weight, and portable design permits easy assembly and disassembly through small openings and it reduces setup/tear down time by 30%. The first deployment of the new ZR-1 Robot was made in September 2004 at the Cernavoda NPP inspection outage. The unit's reactor type is PHWR-CANDU 6 (electrical capacity 706 MWe), using natural uranium; the nuclear fuel is manufactured in Romania. The Cernavoda nuclear power plant Unit 1 has four CANDU - design steam generators that have been in service since 1996. The paper presents also the Zetec's field experience and customer experience with this system. It describes the equipment setup in Cernavoda's steam generators mock-up, functional tests and calibration. Finally, provides details on the execution of the inspection, options for standardizing the inspection techniques and conclusions. (authors)

  1. Data analysis algorithms for flaw sizing based on eddy current rotating probe examination of steam generator tubes

    International Nuclear Information System (INIS)

    Bakhtiari, S.; Elmer, T.W.

    2009-01-01

    Computer-aided data analysis tools can help improve the efficiency and reliability of flaw sizing based on nondestructive examination data. They can further help produce more consistent results, which is important for both in-service inspection applications and for engineering assessments associated with steam generator tube integrity. Results of recent investigations at Argonne on the development of various algorithms for sizing of flaws in steam generator tubes based on eddy current rotating probe data are presented. The research was carried out as part of the activities under the International Steam Generator Tube Integrity Program (ISG-TIP) sponsored by the U.S. Nuclear Regulatory Commission. A computer-aided data analysis tool has been developed for off-line processing of eddy current inspection data. The main objectives of the work have been to a) allow all data processing stages to be performed under the same user interface, b) simplify modification and testing of signal processing and data analysis scripts, and c) allow independent evaluation of viable flaw sizing algorithms. The focus of most recent studies at Argonne has been on the processing of data acquired with the +Point probe, which is one of the more widely used eddy current rotating probes for steam generator tube examinations in the U.S. The probe employs a directional surface riding differential coil, which helps reduce the influence of tubing artifacts and in turn helps improve the signal-to-noise ratio. Various algorithms developed under the MATLAB environment for the conversion, segmentation, calibration, and analysis of data have been consolidated within a single user interface. Data acquired with a number of standard eddy current test equipment are automatically recognized and converted to a standard format for further processing. Because of its modular structure, the graphical user interface allows user-developed routines to be easily incorporated, modified, and tested independent of the

  2. Application of numerical analysis techniques to eddy current testing for steam generator tubes

    International Nuclear Information System (INIS)

    Morimoto, Kazuo; Satake, Koji; Araki, Yasui; Morimura, Koichi; Tanaka, Michio; Shimizu, Naoya; Iwahashi, Yoichi

    1994-01-01

    This paper describes the application of numerical analysis to eddy current testing (ECT) for steam generator tubes. A symmetrical and three-dimensional sinusoidal steady state eddy current analysis code was developed. This code is formulated by future element method-boundary element method coupling techniques, in order not to regenerate the mesh data in the tube domain at every movement of the probe. The calculations were carried out under various conditions including those for various probe types, defect orientations and so on. Compared with the experimental data, it was shown that it is feasible to apply this code to actual use. Furthermore, we have developed a total eddy current analysis system which consists of an ECT calculation code, an automatic mesh generator for analysis, a database and display software for calculated results. ((orig.))

  3. Review of damages of nuclear power plants steam generator's tubes and way of detecting by using eddy current method

    International Nuclear Information System (INIS)

    Stanic, D.

    1996-01-01

    Steam generator tubing integrity is very important factor for reliable and safe operation of NPP. Several different types of tube degradation mechanisms were experienced in SG operation. To avoid possible tube rupture and primary-to-secondary leak, the EC examination of tubing should be performed. Different eddy current techniques may be used for detecting defects and theirs characterization. A comparison of data analysis results with pulled tube destructive metallography results can provide valuable insights in determining the capability of existing technology and provide guidance for procedure or technology improvements. (author)

  4. Application of eddy currents for identification of dimensional variations in PWR steam generator tubes and detection of stress corrosion cracks

    International Nuclear Information System (INIS)

    Comby, R.; Gourmelon, A.

    1985-01-01

    To avoid the risk of cracking on the secondary side of the roll expansion transition zone in steam generator (SG) tubes, tube profile at the upper face of the tube sheet must comply with specifications laid down by the manufacturer and EDF. EDF has developed an eddy current (EC) signal identification method, used for pre-service testing to detect any deviation in tube profile. Nevertheless, circumferential or longitudinal stress corrosion cracks (SCC), initiated on the primary side, have appeared on some SGs. A special rotating probe was used on these generators. The results of these checks have been correlated with metallurgical examination of the extracted tubes

  5. Experimental study of the processes accompanying argon breakdown in a long discharge tube at a reduced pressure

    Energy Technology Data Exchange (ETDEWEB)

    Meshchanov, A. V.; Ionikh, Yu. Z., E-mail: y.ionikh@spbu.ru; Shishpanov, A. I.; Kalinin, S. A. [St. Petersburg State University (Russian Federation)

    2016-10-15

    Results are presented from experimental studies of the breakdown stage of a low-pressure discharge (1 and 5 Torr) in a glass tube the length of which (75 cm) is much larger than its diameter (2.8 cm). Breakdowns occurred under the action of positive voltage pulses with an amplitude of up to 9.4 kV and a characteristic rise time of 2–50 μs. The discharge current in the steady-state mode was 10–120 mA. The electrode voltage, discharge current, and radiation from the discharge gap were detected simultaneously. The dynamic breakdown voltage was measured, the prebreakdown ionization wave was recorded, and its velocity was determined. The dependence of the discharge parameters on the time interval between voltage pulses (the socalled “memory effect”) was analyzed. The memory effect manifests itself in a decrease or an increase in the breakdown voltage and a substantial decrease in its statistical scatter. The time interval between pulses in this case can reach 0.5 s. The effect of illumination of the discharge tube with a light source on the breakdown was studied. It is found that the irradiation of the anode region of the tube by radiation with wavelengths of ≤500 nm substantially reduces the dynamic breakdown voltage. Qualitative explanations of the obtained results are offered.

  6. Feasibility Test with a STS304 tube of the Eddy Current Test using a Bobbin Probe for the SMART SG Tube Inspection

    International Nuclear Information System (INIS)

    Lee, Yoon Sang; Jung, Hyun Kyu; Choung, Yun Hang

    2010-01-01

    The SMART SG tubes will be made of Alloy 690. The outside diameter will be 17 mm and the thickness will be 2.5 mm. They will be assembled helically around, and their innermost diameter will be about 600 mm and the total length will be about 32 meters. For the sake of safety, SMART SG tubes are designed for use with thick tubes such as 2.5 mm thickness compared to about 1 mm thickness of normal Korean standard pressurized water reactor tubes. Due to using thick tubes such as the 2.5 mm varieties, it was doubted that the Eddy Current Testing Method (ECT) would be a feasible method. Therefore we are trying to check the feasibility of the ECT using the substitute material STS304 tube instead of Alloy 690 tubes with the bobbin type ECT probe. The previous paper reported the feasibility of the ECT using modeling, but this paper will report the preliminary experimental results and comparison with the previous results of the modeling for the STS304 tube

  7. An integrated automatic system for the eddy-current testing of the steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Hee Gon; Choi, Seong Su [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center

    1995-12-31

    This research project was focused on automation of steam generator tubes inspection for nuclear power plants. ECT (Eddy Current Testing) inspection process in nuclear power plants is classified into 3 subprocesses such as signal acquisition process, signal evaluation process, and inspection planning and data management process. Having been automated individually, these processes were effectively integrated into an automatic inspection system, which was implemented in HP workstation with expert system developed (author). 25 refs., 80 figs.

  8. An integrated automatic system for the eddy-current testing of the steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Hee Gon; Choi, Seong Su [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center

    1996-12-31

    This research project was focused on automation of steam generator tubes inspection for nuclear power plants. ECT (Eddy Current Testing) inspection process in nuclear power plants is classified into 3 subprocesses such as signal acquisition process, signal evaluation process, and inspection planning and data management process. Having been automated individually, these processes were effectively integrated into an automatic inspection system, which was implemented in HP workstation with expert system developed (author). 25 refs., 80 figs.

  9. Removing Eddy-current probe wobble noise from steam generator tubes testing using wavelet transform

    International Nuclear Information System (INIS)

    Lopez, Luiz Antonio Negro Martin; Ting, Daniel Kao Sun; Upadhyaya, Belle R.

    2005-01-01

    One of the most import nondestructive evaluation (NDE) applied to steam generator tubes inspection is the electromagnetic Eddy-Current testing (ECT). The signals generated in this NDE, in general, contain many noises which make difficult the interpretation and analysis of ECT signals. One of the noises present in the signals is the probe wobble noise, which is caused by the existing slack between the probe and the tube. In this work, Wavelet Transform (WT) is used in the probe wobble de-noising. WT is a relatively recent mathematical tool, which allows local analysis of non stationary signals such as ECT signals. This is a great advantage of WT when compared with other analysis tools such as Fourier Transform. However, using WT involves wavelets and coefficients selection as well as choosing the number of decomposition level needed. This work presents a probe wobble de-noising method when used in conjunction with the traditional ECT evaluation. Comparative results using several WT applied do Eddy-Current signals are presented in a reliable way, in other words, without loss of inherent defect information. A stainless steel tube, with 2 artificial defects generated by electro-erosion, was inspected by a ZETEC MIZ-17ET ECT equipment. The signals were de-noised through several different WT and the results are presented. The method offer good results and is a promising method because allows for the removal of Eddy-Current signals probe wobble effect without loss of essential signal information. (author)

  10. SU-F-J-39: Dose Reduction Strategy Using Attenuation-Based Tube Current Modulation Method in CBCT for IGRT

    Energy Technology Data Exchange (ETDEWEB)

    Son, K; Lee, H; Kim, C; Cho, S [KAIST, Daejeon (Korea, Republic of); Kim, J [Yonsei Cancer Center, Seoul (Korea, Republic of)

    2016-06-15

    Purpose: To reduce radiation dose to the patients, tube current modulation (TCM) method has been actively used in diagnostic CT systems. However, TCM method has not yet been applied to a kV-CBCT system on a LINAC machine. The purpose of this study is to investigate whether the use of TCM method is desirable in kV-CBCT system for IGRT. We have developed an attenuation-based tube current modulation (a-TCM) method using the prior knowledge of treatment CT image of a patient. Methods: Patients go through a diagnostic CT scan for RT planning; therefore, using this prior information of CT images, one can estimate the total attenuation of an x-ray through the patient body in a CBCT setting for radiation therapy. We performed a numerical study incorporating major factors into account such as polychromatic x-ray, scatter, noise, and bow-tie filter to demonstrate that a-TCM method can produce equivalent quality of images at reduced imaging radiation doses. Using the CT projector program, 680 projection images of the pediatric XCAT phantom were obtained both in conventional scanning condition, i.e., without modulating the tube current, and in the proposed a-TCM scanning condition. FDK reconstruction algorithm was used for image reconstruction, and the organ dose due to imaging radiation has been calculated in both cases and compared using GATE/Geant4 simulation toolkit. Results: Reconstructed CT images in the a-TCM method showed similar SSIM values and noise properties to the reference images acquired by the conventional CBCT. In addition, reduction of organ doses ranged from 12% to 27%. Conclusion: We have successfully demonstrated the feasibility and dosimetric merit of the a-TCM method for kV-CBCT, and envision that it can be a useful option of CBCT scanning that provides patient dose reduction without degrading image quality.

  11. Wavelets transforms and fuzzy logic in the eddy-current inspection of nuclear power plants steam generator tubes

    International Nuclear Information System (INIS)

    Lopez, Luiz Antonio Negro Martin

    2002-01-01

    Nuclear power plants steam generators around the world have presented early damage history in their tubes, caused either by design errors or by inappropriate operation, which besides reducing the availability and the safety of the nuclear power plants it also generates heavy economical burden. To monitor the steam generators operational condition, the Eddy Current testing of their tubes is the non destructive method used to detect, localize, classify and to size the defects. The inspection is performed by inserting probes with coils in the tubes generating a signal correlated to the defect. These signals produced by the probe electric circuit are composed by the resistance and the inductive components which can be combined to produce a Lissajous figure in the complex plane. However, Eddy-Current signals contain noise which induce subjectivity inducing to errors in the inspector diagnosis. It is not uncommon to have different diagnosis from two inspectors about the same signal. The present work has the objective of supplying a methodology to analyze the signals which could help the inspector in the difficult task of interpreting the Eddy Current signals. It is proposed a method to remove the noise based on Wavelets Transforms. It is also proposed a normalization in the signal phase angle measurements. Furthermore, two additional characteristics are also studied, namely: the signal amplitudes and the widths of the Lissajous petals. The use of a Fuzzy Logic based inference engine is also developed and its use is demonstrated to be viable. The defects studied in this work are those which produces volumetric changes in the material. In order to test the proposed methodology, several artificial defects were produced in tubes using different types of materials like: brass, 316L stainless steel and Inconel 600 to produce a experimental data base. An Eddy-Current inspection equipment, the MIZ-17ET was used. Around 1000 time series signals of defects were acquired through

  12. Investigation of the influence of image reconstruction filter and scan parameters on operation of automatic tube current modulation systems for different CT scanners

    International Nuclear Information System (INIS)

    Sookpeng, Supawitoo; Martin, Colin J.; Gentle, David J.

    2015-01-01

    Variation in the user selected CT scanning parameters under automatic tube current modulation (ATCM) between hospitals has a substantial influence on the radiation doses and image quality for patients. The aim of this study was to investigate the effect of changing image reconstruction filter and scan parameter settings on tube current, dose and image quality for various CT scanners operating under ATCM. The scan parameters varied were pitch factor, rotation time, collimator configuration, kVp, image thickness and image filter convolution (FC) used for reconstruction. The Toshiba scanner varies the tube current to achieve a set target noise. Changes in the FC setting and image thickness for the first reconstruction were the major factors affecting patient dose. A two-step change in FC from smoother to sharper filters doubles the dose, but is counterbalanced by an improvement in spatial resolution. In contrast, Philips and Siemens scanners maintained tube current values similar to those for a reference image and patient, and the tube current only varied slightly for changes in individual CT scan parameters. The selection of a sharp filter increased the image noise, while use of iDose iterative reconstruction reduced the noise. Since the principles used by CT manufacturers for ATCM vary, it is important that parameters which affect patient dose and image quality for each scanner are made clear to operator to aid in optimisation. (authors)

  13. Iterative reconstruction for quantitative computed tomography analysis of emphysema: consistent results using different tube currents

    Directory of Open Access Journals (Sweden)

    Yamashiro T

    2015-02-01

    Full Text Available Tsuneo Yamashiro,1 Tetsuhiro Miyara,1 Osamu Honda,2 Noriyuki Tomiyama,2 Yoshiharu Ohno,3 Satoshi Noma,4 Sadayuki Murayama1 On behalf of the ACTIve Study Group 1Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara, Okinawa, Japan; 2Department of Radiology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; 3Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan; 4Department of Radiology, Tenri Hospital, Tenri, Nara, Japan Purpose: To assess the advantages of iterative reconstruction for quantitative computed tomography (CT analysis of pulmonary emphysema. Materials and methods: Twenty-two patients with pulmonary emphysema underwent chest CT imaging using identical scanners with three different tube currents: 240, 120, and 60 mA. Scan data were converted to CT images using Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D and a conventional filtered-back projection mode. Thus, six scans with and without AIDR3D were generated per patient. All other scanning and reconstruction settings were fixed. The percent low attenuation area (LAA%; < -950 Hounsfield units and the lung density 15th percentile were automatically measured using a commercial workstation. Comparisons of LAA% and 15th percentile results between scans with and without using AIDR3D were made by Wilcoxon signed-rank tests. Associations between body weight and measurement errors among these scans were evaluated by Spearman rank correlation analysis. Results: Overall, scan series without AIDR3D had higher LAA% and lower 15th percentile values than those with AIDR3D at each tube current (P<0.0001. For scan series without AIDR3D, lower tube currents resulted in higher LAA% values and lower 15th percentiles. The extent of emphysema was significantly different between each pair among scans when not using AIDR3D (LAA%, P<0.0001; 15th percentile, P<0.01, but was not

  14. Eddy current inspection of tubing; Inspeccion de tubos por corrientes de Foucault

    Energy Technology Data Exchange (ETDEWEB)

    Bauza, J L. R.; Herrero, J; Diaz, J

    1966-07-01

    The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)

  15. A study on characteristic of glass dosimeter according to grade change of tube current

    Energy Technology Data Exchange (ETDEWEB)

    Son, Jin Hyun; Kim, Seong Ho; Mun, Hyun Jun; Kim, Lyun Kyun; Son, In Hwa; Kim, Young Jun; Min, Jung Whan [Dept. of Radiological Science, Shingu University, Sungnam (Korea, Republic of); Kim, Ki Won [Dept. of Radiology, Samsung Medical Center, Seoul (Korea, Republic of)

    2014-06-15

    This study was evaluated the linearity and reproducibility according to dose, and reproducibility according to delay time by changing tube current amount (5 mAs, 10 mAs, 16 mAs, 20 mAs, 25 mAs, 32 mAs respectively, which are low energy radiations) using Glass Dosimeter (GD) and piranha semiconductor dosimeter which are used for measuring exposure dose. Measurements of radiation dose were performed using external detector of piranha 657 which is multi-function QA device (RTI Electronic, Sweden). Conditions of measurement were 80 kVp, SSD 100 and exposure region is 10 cm x 10 cm. Glass dosimeter was exposed to radiation. Twenty-four glass dosimeters were divided into six groups (5 mAs, 10 mAs, 16 mAs, 20 mAs, 25 mAs, 32 mAs respectively), then measured. This study was resulted by measuring the linearity and reproducibility according to change of tube current in low energy field. In dose characteristic of GD, this study could be useful as previous study with regard to dose characteristic according to change of tube voltage in low energy field.

  16. Treatment with some anti-inflammatory drugs reduces germ tube formation in Candida albicans strains

    Directory of Open Access Journals (Sweden)

    Elena Rusu

    2014-12-01

    Full Text Available Candida albicans is an opportunistic dimorphic fungus that inhabits various host mucosal sites. It can cause both superficial and serious systemic disease. Conversion from the yeast to the hyphal form has been associated with increased virulence and mucosal invasiveness. The aim of this study was to investigate the effect of sodium diclofenac and aspirin on germs tube formation of different Candida albicans strains. Prostaglandins may play an important role in fungal colonization. Nonsteroidal anti-inflammatory drugs are inhibitors of the cyclooxygenase isoenzymes. These drugs specifically block the biosynthesis of mammalian prostaglandins by inhibiting one or both of cyclooxygenase isoenzymes. In tests for germ tube formation sodium diclofenac reduced the filamentation to the 12.5%- 5.1%. In the presence of aspirin the filamentation was reduced up to 85-45% depending on the tested strain. Our results suggest that cyclooxygenase-depending synthesis of fungal prostaglandins is important for morphogenesis and fungal virulence. Inhibitors of cyclooxygenase isoensymes (aspirin and diclofenac are effective in decreasing germ tube formation of Candida albicans.

  17. Particular treatments in Eddy current technique. Application to the control of corrugated tubes

    International Nuclear Information System (INIS)

    1982-11-01

    When the testing of a given product shows that, owing to a particular shape of this product or to its environment, disturbing effects can hide the presence of harmful defects, use must be made of testing artifices or particular treatments enabling an efficient examination to be made. On this score, many eddy current problems are solved by means of the following processes: - use of specific sensors adapted to the geometry of the product, - spectral analysis of the analog results of analyses, - combination of the results of analyses obtained simultaneously at different frequencies (multifrequency techniques). An example of an application is given for corrugated tubes achieved by hollow and helical milling of smooth tubes [fr

  18. Performance demonstration tests for eddy current inspection of steam generator tubing

    International Nuclear Information System (INIS)

    Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.

    1996-05-01

    This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given

  19. Performance demonstration tests for eddy current inspection of steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.

    1996-05-01

    This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given.

  20. Volume of interest CBCT and tube current modulation for image guidance using dynamic kV collimation

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, David, E-mail: david.parsons@dal.ca, E-mail: james.robar@nshealth.ca [Department of Physics and Atmospheric Science, Dalhousie University, 5820 University Avenue, Halifax, Nova Scotia B3H 1V7 (Canada); Robar, James L., E-mail: david.parsons@dal.ca, E-mail: james.robar@nshealth.ca [Department of Radiation Oncology and Department of Physics and Atmospheric Science, Dalhousie University, 5820 University Avenue, Halifax, Nova Scotia B3H 1V7 (Canada)

    2016-04-15

    Purpose: The focus of this work is the development of a novel blade collimation system enabling volume of interest (VOI) CBCT with tube current modulation using the kV image guidance source on a linear accelerator. Advantages of the system are assessed, particularly with regard to reduction and localization of dose and improvement of image quality. Methods: A four blade dynamic kV collimator was developed to track a VOI during a CBCT acquisition. The current prototype is capable of tracking an arbitrary volume defined by the treatment planner for subsequent CBCT guidance. During gantry rotation, the collimator tracks the VOI with adjustment of position and dimension. CBCT image quality was investigated as a function of collimator dimension, while maintaining the same dose to the VOI, for a 22.2 cm diameter cylindrical water phantom with a 9 mm diameter bone insert centered on isocenter. Dose distributions were modeled using a dynamic BEAMnrc library and DOSXYZnrc. The resulting VOI dose distributions were compared to full-field CBCT distributions to quantify dose reduction and localization to the target volume. A novel method of optimizing x-ray tube current during CBCT acquisition was developed and assessed with regard to contrast-to-noise ratio (CNR) and imaging dose. Results: Measurements show that the VOI CBCT method using the dynamic blade system yields an increase in contrast-to-noise ratio by a factor of approximately 2.2. Depending upon the anatomical site, dose was reduced to 15%–80% of the full-field CBCT value along the central axis plane and down to less than 1% out of plane. The use of tube current modulation allowed for specification of a desired SNR within projection data. For approximately the same dose to the VOI, CNR was further increased by a factor of 1.2 for modulated VOI CBCT, giving a combined improvement of 2.6 compared to full-field CBCT. Conclusions: The present dynamic blade system provides significant improvements in CNR for the same

  1. Effect of drag-reducing polymers on Tubing Performance Curve (TPC) in vertical gas-liquid flows

    NARCIS (Netherlands)

    Shoeibi Omrani, P.; Veltin, J.; Turkenburg, D.H.

    2014-01-01

    This paper discusses the effect of drag reducing polymers on the Tubing Performance Curve (TPC) of vertical air-water flows at near atmospheric conditions. The effect of polymer concentration, liquid and gas flow rates on the pressure drop curve (Tubing Performance Curve) was investigated

  2. CT breast dose reduction with the use of breast positioning and organ-based tube current modulation.

    Science.gov (United States)

    Fu, Wanyi; Tian, Xiaoyu; Sturgeon, Gregory M; Agasthya, Greeshma; Segars, William Paul; Goodsitt, Mitchell M; Kazerooni, Ella A; Samei, Ehsan

    2017-02-01

    This study aimed to investigate the breast dose reduction potential of a breast-positioning (BP) technique for thoracic CT examinations with organ-based tube current modulation (OTCM). This study included 13 female anthropomorphic computational phantoms (XCAT, age range: 27-65 y.o., weight range: 52-105.8 kg). Each phantom was modified to simulate three breast sizes in standard supine geometry. The modeled breasts were then morphed to emulate BP that constrained the majority of the breast tissue inside the 120° anterior tube current (mA) reduction zone. The OTCM mA value was modeled using a ray-tracing program, which reduced the mA to 20% in the anterior region with a corresponding increase to the posterior region. The organ doses were estimated by a validated Monte Carlo program for a typical clinical CT system (SOMATOM Definition Flash, Siemens Healthcare). The simulated organ doses and organ doses normalized by CTDI vol were used to compare three CT protocols: attenuation-based tube current modulation (ATCM), OTCM, and OTCM with BP (OTCM BP ). On average, compared to ATCM, OTCM reduced breast dose by 19.3 ± 4.5%, whereas OTCM BP reduced breast dose by 38.6 ± 8.1% (an additional 23.8 ± 9.4%). The dose saving of OTCM BP was more significant for larger breasts (on average 33, 38, and 44% reduction for 0.5, 1, and 2 kg breasts, respectively). Compared to ATCM, OTCM BP also reduced thymus and heart dose by 15.1 ± 7.4% and 15.9 ± 6.2% respectively. In thoracic CT examinations, OTCM with a breast-positioning technique can markedly reduce unnecessary exposure to radiosensitive organs in anterior chest wall, specifically breast tissue. The breast dose reduction is more notable for women with larger breasts. © 2016 American Association of Physicists in Medicine.

  3. Reduced program of inspection by induced currents for condenser of Embalse nuclear power plant

    International Nuclear Information System (INIS)

    Obrutsky, L.; Mendonca, H.

    1986-01-01

    In this work it's presented a reduced inspection in service program by the technique of induced currents to the turbine condenser of Embalse's Power Plant (Cordoba). The authors based its elaboration on the results obtained in the exam of a small number of tubes and on experience obtained through four inspections in the condensers of Atucha I Power Plant, through mathematical models of oxygen and ammoniac distribution in both Power Plants, and its experimental verification in the case of Atucha I. This program improves the quality of inspection thereby reducing time, equipment and personnel employed. (C.M.) [pt

  4. Effect of Localizer Radiography Projection on Organ Dose at Chest CT with Automatic Tube Current Modulation.

    Science.gov (United States)

    Saltybaeva, Natalia; Krauss, Andreas; Alkadhi, Hatem

    2017-03-01

    Purpose To calculate the effect of localizer radiography projections to the total radiation dose, including both the dose from localizer radiography and that from subsequent chest computed tomography (CT) with tube current modulation (TCM). Materials and Methods An anthropomorphic phantom was scanned with 192-section CT without and with differently sized breast attachments. Chest CT with TCM was performed after one localizer radiographic examination with anteroposterior (AP) or posteroanterior (PA) projections. Dose distributions were obtained by means of Monte Carlo simulations based on acquired CT data. For Monte Carlo simulations of localizer radiography, the tube position was fixed at 0° and 180°; for chest CT, a spiral trajectory with TCM was used. The effect of tube start angles on dose distribution was investigated with Monte Carlo simulations by using TCM curves with fixed start angles (0°, 90°, and 180°). Total doses for lungs, heart, and breast were calculated as the sum of the dose from localizer radiography and CT. Image noise was defined as the standard deviation of attenuation measured in 14 circular regions of interest. The Wilcoxon signed rank test, paired t test, and Friedman analysis of variance were conducted to evaluate differences in noise, TCM curves, and organ doses, respectively. Results Organ doses from localizer radiography were lower when using a PA instead of an AP projection (P = .005). The use of a PA projection resulted in higher TCM values for chest CT (P chest CT. © RSNA, 2016 Online supplemental material is available for this article.

  5. Dose reduction in spiral CT angiography of thoracic outlet syndrome by anatomically adapted tube current modulation

    International Nuclear Information System (INIS)

    Mastora, I.; Remy-Jardin, M.; Remy, J.; Suess, C.; Scherf, C.; Guillot, J.P.

    2001-01-01

    The aim of this study was to evaluate dose reduction in spiral CT angiography of the thoracic outlet by on-line tube-current control. Prospectively, 114 patients undergoing spiral CT angiography of the subclavian artery for thoracic outlet arterial syndromes were evaluated with and without tube-current modulation at the same session (scanning parameters for the two successive angiograms, one in the neutral position and one after the postural maneuver): 140 kV; 206 mA; scan time 0.75 s; collimation 3 mm; pitch = (1). The dose reduction system was applied in the neutral position in the first 92 consecutive patients and after postural maneuver in the remaining 22 consecutive patients. Dose reduction and image quality were analyzed in the overall study group (group 1; n = 114). The influence of the arm position was assessed in 44 of the 114 patients (group 2), matched by the transverse diameter of the upper thorax. The mean dose reduction was 33 % in group 1 (range 22-40 %) and 34 % in group 2 (range 26-40 %). In group 2 the only difference in image quality was a significantly higher frequency of graininess on low-dose scans compared with reference scans whatever the patient's arm position, graded as minimal in 38 of the 44 patients (86 %). When the low-dose technique was applied after postural maneuver in group 2: (a) the mean dose reduction was significantly higher (35 vs 32 % in the neutral position; p = 0.006); (b) graininess was less frequent (82 vs 91 % in the neutral position); and (c) the percentage of graininess graded as minimal was significantly higher (83 vs 70 % in the neutral position; p = 0.2027). On-line tube-current modulation enables dose reduction on high-quality, diagnostic spiral CT angiograms of the thoracic outlet and should be applied during data acquisition in the neutral position and after postural maneuver for optimal use. (orig.)

  6. Dose reduction in spiral CT angiography of thoracic outlet syndrome by anatomically adapted tube current modulation

    Energy Technology Data Exchange (ETDEWEB)

    Mastora, I.; Remy-Jardin, M.; Remy, J. [Dept. of Radiology, University Center Hospital Calmette, Lille (France); Medical Research Group, Lille (France); Suess, C.; Scherf, C. [Siemens Medical Systems, Forcheim (Germany); Guillot, J.P. [Dept. of Radiology, University Center Hospital Calmette, Lille (France)

    2001-04-01

    The aim of this study was to evaluate dose reduction in spiral CT angiography of the thoracic outlet by on-line tube-current control. Prospectively, 114 patients undergoing spiral CT angiography of the subclavian artery for thoracic outlet arterial syndromes were evaluated with and without tube-current modulation at the same session (scanning parameters for the two successive angiograms, one in the neutral position and one after the postural maneuver): 140 kV; 206 mA; scan time 0.75 s; collimation 3 mm; pitch = (1). The dose reduction system was applied in the neutral position in the first 92 consecutive patients and after postural maneuver in the remaining 22 consecutive patients. Dose reduction and image quality were analyzed in the overall study group (group 1; n = 114). The influence of the arm position was assessed in 44 of the 114 patients (group 2), matched by the transverse diameter of the upper thorax. The mean dose reduction was 33 % in group 1 (range 22-40 %) and 34 % in group 2 (range 26-40 %). In group 2 the only difference in image quality was a significantly higher frequency of graininess on low-dose scans compared with reference scans whatever the patient's arm position, graded as minimal in 38 of the 44 patients (86 %). When the low-dose technique was applied after postural maneuver in group 2: (a) the mean dose reduction was significantly higher (35 vs 32 % in the neutral position; p = 0.006); (b) graininess was less frequent (82 vs 91 % in the neutral position); and (c) the percentage of graininess graded as minimal was significantly higher (83 vs 70 % in the neutral position; p = 0.2027). On-line tube-current modulation enables dose reduction on high-quality, diagnostic spiral CT angiograms of the thoracic outlet and should be applied during data acquisition in the neutral position and after postural maneuver for optimal use. (orig.)

  7. Investigation and application of reduced-order methods for flows study in heat exchanger tube bundles

    International Nuclear Information System (INIS)

    Pomarede, M.

    2012-01-01

    The objective of this thesis is to study the ability of model reduction for investigations of flow-induced vibrations in heat exchangers tube bundle systems.These mechanisms are a cause of major concern because heat exchangers are key elements of nuclear power plants and on-board stoke-holds.In a first part, we give a recall on heat exchangers functioning and on vibratory problems to which they are prone. Then, complete calculations leaded with the CFD numerical code Code-Saturne are carried out, first for the flow around a single circular cylinder (fixed then elastically mounted) and then for the case of a tube bundle system submitted to cross-flow. Reduced-order method POD is applied to the flow resolution with fixed structures. The obtained results show the efficiency of this technique for such configurations, using stabilization methods for the dynamical system resolution in the tube-bundle case. Multiphase-POD, which is a method enabling the adaptation of POD to fluid-structure interactions, is applied. Large displacements of a single cylinder elastically mounted under cross-flow, corresponding to the lock-in phenomenon,are well reproduced with this reduction technique. In the same way, large displacements of a confined moving tube in a bundle are shown to be faithfully reconstructed.Finally, the use of model reduction is extended to parametric studies. First, we propose to use the method which consists in projecting Navier-Stokes equations for several values of the Reynolds number on to a unique POD basis. The results obtained confirm the fact that POD predictability is limited to a range of parameter values. Then, a basis interpolation method, constructed using Grassmann manifolds and allowing the construction of a POD basis from other pre-calculated basis, is applied to basic cases. (author)

  8. The Cause of an Eddy Current Signal Noise from a Steam Generator Tube and its Effect on the Detectability of a Crack

    International Nuclear Information System (INIS)

    Lee, Deok Hyun; Choi, Myung Sik; Hur, Do Haeng; Kim, Kyung Mo; Han, Jung Ho

    2008-01-01

    An eddy current inspection has been applied for a pre-service and in-service examination of a steam generator in nuclear power plants. The experience from the inspection of steam generators showed that many plants had an excessive number of tubes with eddy current noise signals over several hundreds, which originated from manufacturing anomalies. The plants in U.S suffered significant downstream inspection costs, history reviews, and diagnostic testing because some signals resembled flaws and others masked a flaw. These lessens learned resulted in issuing the guidelines for steam generator tubing specifications and repair, in order to reduce the number of anomalous signals in the tubes and also to provide the requirement of a signal to noise ratio by applying a field type examination with bobbin coil eddy current probes at a manufacturing process. Besides the noise signals of a bobbin coil eddy current probe from manufacturing anomalies, the excessive background noise of the rotating coil eddy current probe signal is frequently observed from a tube and it negatively affects the detection and sizing estimate of a defect. Since the inspection intervals are being extended up to 60 months for the more recent steam generator of corrosion resistant alloy 690TT tubing, the detection of an earlier crack and an accurate sizing are becoming more important in the activity of a non-destructive examination. In this study, the cause of an eddy current signal noise of a rotating coil probe from a steam generator tube was examined and its influence on the detectability of a crack was analyzed

  9. A review of current knowledge on the effects of hydrogen on the pressure tubes of Ontario Hydro operating reactors

    International Nuclear Information System (INIS)

    Leger, M.

    1982-01-01

    Since the occurrence of cracking in Zr-2.5 wt% Nb pressure tubes in Pickering 'A' units 3 and 4 in 1974/75 a great deal of information on the behaviour of hydrogen in pressure tube materials has been generated through research effort by both AECL and Ontario Hydro. In order to use this information effectively and to provide direction and co-ordination for ongoing research, a review of available information and current concerns on hydrogen in pressure tubes was undertaken. The review was divided into two main areas of interest: hydrogen ingress and hydride effects. The uncertainties in the rates of hydrogen ingress into the pressure tubes have been found to be very large. On the basis of current knowledge, predictions of the future behaviour of pressure tubes due to hydride effects are extremely difficult

  10. Signal to noise ratio enhancement for Eddy Current testing of steam generator tubes in PWR's

    International Nuclear Information System (INIS)

    Georgel, B.

    1985-01-01

    Noise reduction is a compulsory task when we try to recognize and characterize flaws. The signals we deal with come from Eddy Current testings of steam generator steel tubes. We point out the need for a spectral invariant in digital spectral analysis of 2 components signals. We make clear the pros and cons of classical passband filtering and suggest the use of a new noise cancellation method first discussed by Moriwaki and Tlusty. We generalize this tricky technique and prove it is a very special case of the well-known Wiener filter. In that sense the M-T method is shown to be optimal. 6 refs

  11. Sensitive technique for detecting outer defect on tube with remote field eddy current testing

    International Nuclear Information System (INIS)

    Kobayashi, Noriyasu; Nagai, Satoshi; Ochiai, Makoto; Jimbo, Noboru; Komai, Masafumi

    2008-01-01

    In the remote field eddy current testing, we proposed the method of enhancing the magnetic flux density in the vicinity of an exciter coil by controlling the magnetic flux direction for increasing the sensitivity of detecting outer defects on a tube and used the flux guide made of a magnetic material for the method. The optimum structural shape of the flux guide was designed by the magnetic field analysis. On the experiment with the application of the flux guide, the magnetic flux density increased by 59% and the artificial defect detection signal became clear. We confirmed the proposed method was effective in a high sensitivity. (author)

  12. Coaxial guiding assembly for internal through-passing probe for eddy current testing of tubes

    International Nuclear Information System (INIS)

    Kubis, S.; Holec, P.

    1989-01-01

    The device features guiding cases mounted on springs provided on the peripheries with two rows of radial openings into which are wound flexible fibres parallel with the case axis. The advantage of the design is that active elements which provide the coaxial guiding of the probe are oriented in the direction of the probe movement. This significantly reduces friction between the probe and the internal wall of the tube and thereby also wear of the guide parts of the probe. (J.B.). 2 figs

  13. Oral care may reduce pneumonia in the tube-fed elderly: a preliminary study.

    Science.gov (United States)

    Maeda, Keisuke; Akagi, Junji

    2014-10-01

    Pneumonia is one of the most important diseases in terms of mortality in the elderly. In particular, bedridden patients who are forbidden oral ingestion during enteral nutrition may have a poor outcome resulting from a respiratory infection. Oral hygiene can play a positive role in preventing aspiration pneumonia in the elderly. The aim of this study was to investigate the effectiveness of oral hygiene for bedridden and tube-fed patients at an increased risk of pneumonia. This retrospective study was conducted from July 2011 to June 2013 on a long-term-care hospital unit. The oral care protocol (OCP) intervention commenced in July 2012, during the study period. The subjects of this study were 63 elderly patients with a mean age of 81.7 years. Thirty-one patients were enrolled in the OCP intervention group, and the mean observation length was 130.4 days; the mean observation length for the 32 patients in the control group was 128.4 days. The incidence of pneumonia and the numbers of days with a recorded fever, antibiotics administration, blood tests, and radiological examinations were reduced from 1.20 to 0.45, 24.57 to 17.48, 25.52 to 10.12, 10.91 to 6.54, and 6.33 to 3.09 %, respectively. These reductions were significantly less in the OCP intervention group. In conclusion, the results of the present study suggest that daily oral care for tube-fed patients who do not receive nutrition by mouth reduced the incidence of pneumonia. In addition to patients consuming food by mouth, all tube-fed patients require dedicated oral care to maintain healthy oral conditions.

  14. The feasibility of a regional CTDIvol to estimate organ dose from tube current modulated CT exams

    International Nuclear Information System (INIS)

    Khatonabadi, Maryam; Kim, Hyun J.; Lu, Peiyun; McMillan, Kyle L.; Cagnon, Chris H.; McNitt-Gray, Michael F.; DeMarco, John J.

    2013-01-01

    Purpose: In AAPM Task Group 204, the size-specific dose estimate (SSDE) was developed by providing size adjustment factors which are applied to the Computed Tomography (CT) standardized dose metric, CTDI vol . However, that work focused on fixed tube current scans and did not specifically address tube current modulation (TCM) scans, which are currently the majority of clinical scans performed. The purpose of this study was to extend the SSDE concept to account for TCM by investigating the feasibility of using anatomic and organ specific regions of scanner output to improve accuracy of dose estimates. Methods: Thirty-nine adult abdomen/pelvis and 32 chest scans from clinically indicated CT exams acquired on a multidetector CT using TCM were obtained with Institutional Review Board approval for generating voxelized models. Along with image data, raw projection data were obtained to extract TCM functions for use in Monte Carlo simulations. Patient size was calculated using the effective diameter described in TG 204. In addition, the scanner-reported CTDI vol (CTDI vol,global ) was obtained for each patient, which is based on the average tube current across the entire scan. For the abdomen/pelvis scans, liver, spleen, and kidneys were manually segmented from the patient datasets; for the chest scans, lungs and for female models only, glandular breast tissue were segmented. For each patient organ doses were estimated using Monte Carlo Methods. To investigate the utility of regional measures of scanner output, regional and organ anatomic boundaries were identified from image data and used to calculate regional and organ-specific average tube current values. From these regional and organ-specific averages, CTDI vol values, referred to as regional and organ-specific CTDI vol , were calculated for each patient. Using an approach similar to TG 204, all CTDI vol values were used to normalize simulated organ doses; and the ability of each normalized dose to correlate with

  15. Dose reduction in CT examination of children by an attenuation-based on-line modulation of tube current (CARE Dose)

    International Nuclear Information System (INIS)

    Greess, Holger; Noemayr, Anton; Baum, Ulrich; Lell, Michael; Boewing, Bernhard; Bautz, Werner A.; Wolf, Heiko; Kalender, Willi

    2002-01-01

    In a controlled patient study we investigated the potential of attenuation-based on-line modulation of the tube current to reduce milliampere values (mAs) in CT examinations of children without loss of image quality. mAs can be reduced for non-circular patient cross sections without an increase in noise if tube current is reduced at those angular positions where the patient diameter and, consequently, attenuation are small. We investigated a technical approach with an attenuation-based on-line control for the tube current realised as a work-in-progress implementation. The CT projection data are analysed in real time to determine optimal mAs values for each projection angle. We evaluated mAs reduction for 100 spiral CT examinations with attenuation-based on-line modulation of the tube current in a group of children. Two radiologists evaluated image quality by visual interpretation in consensus. We compared the mAs values read from the CT scanner with preset mAs of a standard protocol. Four different scan regions were examined in spiral technique (neck, thorax, abdomen, thorax and abdomen). We found the mAs product to be reduced typically by 10-60% depending on patient geometry and anatomical regions. The mean reduction was 22.3% (neck 20%, thorax 23%, abdomen 23%, thorax and abdomen 22%). In general, no deterioration of image quality was observed. There was no correlation between the age and the mean mAs reduction in the different anatomical regions. By classifying the children respectively to their weight, there is a positive trend between increasing weight and mAs reduction. We conclude that mAs in spiral CT examinations of children can be reduced substantially by attenuation-based on-line modulation of the tube current without deterioration of image quality. Attenuation-based on-line modulation of tube current is efficient and practical for reducing dose exposure to children. (orig.)

  16. Effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies

    International Nuclear Information System (INIS)

    Murase, Kenya; Nanjo, Takafumi; Ii, Satoshi; Miyazaki, Shohei; Hirata, Masaaki; Sugawara, Yoshifumi; Kudo, Masayuki; Sasaki, Kousuke; Mochizuki, Teruhito

    2005-01-01

    The purpose of this study was to investigate the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using multi-detector row CT (MDCT). Following the standard CT perfusion study protocol, continuous (cine) scans (1 s/rotation x 60 s) consisting of four 5 mm thick contiguous slices were performed using an MDCT scanner with a tube voltage of 80 kVp and a tube current of 200 mA. We generated the simulated images with tube currents of 50 mA, 100 mA and 150 mA by adding the corresponding noise to the raw scan data of the original image acquired above using a noise simulation tool. From the original and simulated images, we generated the functional images of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) in seven patients with cerebrovascular disease, and compared the correlation coefficients (CCs) between the perfusion parameter values obtained from the original and simulated images. The coefficients of variation (CVs) in the white matter were also compared. The CC values deteriorated with decreasing tube current. There was a significant difference between 50 mA and 100 mA for all perfusion parameters. The CV values increased with decreasing tube current. There were significant differences between 50 mA and 100 mA and between 100 mA and 150 mA for CBF. For CBV and MTT, there was also a significant difference between 150 mA and 200 mA. This study will be useful for understanding the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using MDCT, and for selecting the tube current

  17. Limiting currents of an unneutralized magnetized electron beam in a cylindrical drift tube

    International Nuclear Information System (INIS)

    Thompson, J.R.; Sloan, M.L.

    1978-01-01

    Results of an investigation of the steady state injection of a uniform unneutralized, magnetized, relativistic electron beam into a cylindrical drift tube are presented. The space-charge-limited current and the asymptotic kinetic energy of electrons on axis is determined both numerically and analytically as a function of the input kinetic energy (γ 0 -1) mc 2 and of the ratio of beam-to-wall radii. A previously cited ''interpolation formula'' is obtained in the pencil beam limit, but more accurate limiting current expressions are developed for other cases (such as the fat beam limit) where the interpolation formula is as much as 20% in error. The corresponding axial electron energy is also found to be significantly smaller than the previously cited value of (γ/sup 1/3/ 0 -1) mc 2 except in the strong pencil beam limit

  18. The counter-current flooding limit in vertical tubes with and without orifices

    International Nuclear Information System (INIS)

    Tye, P.; Davidson, M.; Teyssedou, A.; Tapucu, A.; Matuszkiewicz, A.; Midvidy, W.

    1993-01-01

    For hypothetical loss of coolant accidents in nuclear reactors, rapid reflooding of the core is desirable. In CANDU reactors the cooling water is injected into the headers which are connected to the fuel channels by the feeder pipes. These pipes consist of vertical and horizontal runs; in some feeders, orifices and/or venturi flow meters are installed for flow adjustments and measurements respectively. For certain postulated accident scenarios, steam coming from the fuel channels and/or generated in the hot feeders may flow in the direction opposite to that of the cooling water thereby, creating a vertical or horizontal counter-current two-phase flow. Under these conditions, the rate at which cooling water can enter the fuel channels may be limited by the flooding phenomena. This phenomena is greatly affected by the geometry of the feeder pips, shape and number of fittings, and the flow area restrictions located in the feeders. In this paper the influence that orifice type flow area restrictions have on the counter-current flooding limit (CCFL) in a vertical tube is examined. air and water at close to atmospheric conditions are used as the working fluids. The data collected on the counter-current flooding limit in a vertical tube both with and without flow area restrictions is compared against some of the most commonly used correlations that are available in the open literature. Data on the two-phase counter-current pressure drop below the flooding point are also presented. 12 refs., 10 figs., 1 tab

  19. Method and system for a gas tube switch-based voltage source high voltage direct current transmission system

    Science.gov (United States)

    She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William

    2016-12-13

    A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.

  20. Topogram-based tube current modulation of head computed tomography for optimizing image quality while protecting the eye lens with shielding.

    Science.gov (United States)

    Lin, Ming-Fang; Chen, Chia-Yuen; Lee, Yuan-Hao; Li, Chia-Wei; Gerweck, Leo E; Wang, Hao; Chan, Wing P

    2018-01-01

    Background Multiple rounds of head computed tomography (CT) scans increase the risk of radiation-induced lens opacification. Purpose To investigate the effects of CT eye shielding and topogram-based tube current modulation (TCM) on the radiation dose received by the lens and the image quality of nasal and periorbital imaging. Material and Methods An anthropomorphic phantom was CT-scanned using either automatic tube current modulation or a fixed tube current. The lens radiation dose was estimated using cropped Gafchromic films irradiated with or without a shield over the orbit. Image quality, assessed using regions of interest drawn on the bilateral extraorbital areas and the nasal bone with a water-based marker, was evaluated using both a signal-to-noise ratio (SNR) and contrast-noise ratio (CNR). Two CT specialists independently assessed image artifacts using a three-point Likert scale. Results The estimated radiation dose received by the lens was significantly lower when barium sulfate or bismuth-antimony shields were used in conjunction with a fixed tube current (22.0% and 35.6% reduction, respectively). Topogram-based TCM mitigated the beam hardening-associated artifacts of bismuth-antimony and barium sulfate shields. This increased the SNR by 21.6% in the extraorbital region and the CNR by 7.2% between the nasal bones and extraorbital regions. The combination of topogram-based TCM and barium sulfate or bismuth-antimony shields reduced lens doses by 12.2% and 27.2%, respectively. Conclusion Image artifacts induced by the bismuth-antimony shield at a fixed tube current for lenticular radioprotection were significantly reduced by topogram-based TCM, which increased the SNR of the anthropomorphic nasal bones and periorbital tissues.

  1. Fetal doses to pregnant patients from CT with tube current modulation calculated using Monte Carlo simulations and realistic phantoms

    International Nuclear Information System (INIS)

    Gu, J.; George Xu, X.; Caracappa, P. F.; Liu, B.

    2013-01-01

    To investigate the radiation dose to the fetus using retrospective tube current modulation (TCM) data selected from archived clinical records. This paper describes the calculation of fetal doses using retrospective TCM data and Monte Carlo (MC) simulations. Three TCM schemes were adopted for use with three pregnant patient phantoms. MC simulations were used to model CT scanners, TCM schemes and pregnant patients. Comparisons between organ doses from TCM schemes and those from non-TCM schemes show that these three TCM schemes reduced fetal doses by 14, 18 and 25 %, respectively. These organ doses were also compared with those from ImPACT calculation. It is found that the difference between the calculated fetal dose and the ImPACT reported dose is as high as 46 %. This work demonstrates methods to study organ doses from various TCM protocols and potential ways to improve the accuracy of CT dose calculation for pregnant patients. (authors)

  2. A pulsed eddy current probe for inspection of support plates from within Alloy-800 steam generator tubes

    International Nuclear Information System (INIS)

    Krause, T. W.; Babbar, V. K.; Underhill, P. R.

    2014-01-01

    Support plate degradation and fouling in nuclear steam generators (SGs) can lead to SG tube corrosion and loss of efficiency. Inspection and monitoring of these conditions can be integrated with preventive maintenance programs, thereby advancing station-life management processes. A prototype pulsed eddy current (PEC) probe, targeting inspection issues associated with SG tubes in SS410 tube support plate structures, has been developed using commercial finite element (FE) software. FE modeling was used to identify appropriate driver and pickup coil configurations for optimum sensitivity to changes in gap and offset for Alloy-800 SG tubes passing through 25 mm thick SS410 support plates. Experimental measurements using a probe that was manufactured based on the modeled configuration, were used to confirm the sensitivity of differential PEC signals to changes in relative position of the tube within the tube support plate holes. Models investigated the effect of shift and tilt of tube with respect to hole centers. Near hole centers and for small shifts, modeled signal amplitudes from the differentially connected coil pairs were observed to change linearly with tube shift. This was in agreement with experimentally measured TEC coil response. The work paves the way for development of a system targeting the inspection and evaluation of support plate structures in steam generators

  3. A pulsed eddy current probe for inspection of support plates from within Alloy-800 steam generator tubes

    Science.gov (United States)

    Krause, T. W.; Babbar, V. K.; Underhill, P. R.

    2014-02-01

    Support plate degradation and fouling in nuclear steam generators (SGs) can lead to SG tube corrosion and loss of efficiency. Inspection and monitoring of these conditions can be integrated with preventive maintenance programs, thereby advancing station-life management processes. A prototype pulsed eddy current (PEC) probe, targeting inspection issues associated with SG tubes in SS410 tube support plate structures, has been developed using commercial finite element (FE) software. FE modeling was used to identify appropriate driver and pickup coil configurations for optimum sensitivity to changes in gap and offset for Alloy-800 SG tubes passing through 25 mm thick SS410 support plates. Experimental measurements using a probe that was manufactured based on the modeled configuration, were used to confirm the sensitivity of differential PEC signals to changes in relative position of the tube within the tube support plate holes. Models investigated the effect of shift and tilt of tube with respect to hole centers. Near hole centers and for small shifts, modeled signal amplitudes from the differentially connected coil pairs were observed to change linearly with tube shift. This was in agreement with experimentally measured TEC coil response. The work paves the way for development of a system targeting the inspection and evaluation of support plate structures in steam generators.

  4. Improvement of ISI techniques by multi-frequency eddy current testing method for steam generator tube in PWR plant

    International Nuclear Information System (INIS)

    Endo, Takashi; Kamimura, Takeo; Nishihara, Masatoshi; Araki, Yasuo; Fukui, Shigetaka.

    1982-05-01

    Eddy current flaw detection techniques are applied to the in-service inspection (ISI) of steam generator tubes in pressurized water reactors (PWR) plant. To improve the reliability and operating efficiency of the plants, efforts are being made to develop eddy current testing methods of various kinds. Multi-frequency eddy current testing method, one of new method, has recently been applied to actual heat exchanger tubes, contributing to the improvement of the detectability and signal evaluation of the ISI. The outline of multi-frequency eddy current testing method and its effects on the improvement of flaw detecting and signal evaluation accuracy are described. (author)

  5. An automated eddy current in-service inspection system for nuclear steam generator tubing

    International Nuclear Information System (INIS)

    Wells, N.S.

    1981-06-01

    A prototype steam generator in-service inspection system incorporating remotely-controlled instrumentation linked by a digital transmission line to an instrument and control trailer outside the reactor containment has been designed and manufactured and is presently undergoing field tests. The (Monel 400) steam generator tubes are scanned two at a time using absolute eddy current probes controlled by two remotely-operated probe drives at a scanning speed of 0.5 m/s. The probes are positioned on the tubesheet by a light-weight (1.5 kg) microprocessor-operated tubesheet walker mechanism. Digitized control and data signals are transmitted up to 300 m to the control trailer. There the control and analysis computers extract the relevant signal information and present it in condensed form as labelled graphics on CRT consoles for on-line visual assessment. Hard copy output is also provided for each tube scanned (one per minute). Condensed data is archived on magnetic tapes for additional off-line analysis and comparisons with other inspections

  6. Development and validation of a simulation tool dedicated to eddy current non destructive testing of tubes

    International Nuclear Information System (INIS)

    Reboud, Ch.

    2006-09-01

    Eddy current testing (ECT) technique is widely used in industrial fields such as iron and steel industry. Dedicated simulation tools provide a great assistance for the optimisation of ECT processes. CEA and the Vallourec Research Center have collaborated in order to develop a simulation tool of ECT of tubes. The volume integral method has been chosen for the resolution of Maxwell equations in a stratified medium, in order to get accurate results with a computation time short enough to carry out optimisation or inversion procedures. A fast model has been developed for the simulation of ECT of non magnetic tubes using specific external probes. New flaw geometries have been modelled: holes and notches with flat bottom. Validations of the developments, which have been integrated to the CIVA platform, have been carried out using experimental data recorded in laboratory conditions and in. industrial conditions, successively. The integral equations derived are solved using the Galerkin variant of the method of moments with pulse functions as projection functions. In order to overcome some memory limitations, other projection functions have been considered. A new discretization scheme based on non-uniform B-Splines of degree 1 or 2 has been implemented, which constitutes an original contribution to the existing literature. The decrease of the mesh size needed to get a given accuracy on the result may lead to the simulation of more complex ECT configurations. (author)

  7. Eddy Current Signature Classification of Steam Generator Tube Defects Using A Learning Vector Quantization Neural Network

    International Nuclear Information System (INIS)

    Garcia, Gabe V.

    2005-01-01

    A major cause of failure in nuclear steam generators is degradation of their tubes. Although seven primary defect categories exist, one of the principal causes of tube failure is intergranular attack/stress corrosion cracking (IGA/SCC). This type of defect usually begins on the secondary side surface of the tubes and propagates both inwards and laterally. In many cases this defect is found at or near the tube support plates

  8. Preliminary research on eddy current bobbin quantitative test for heat exchange tube in nuclear power plant

    Science.gov (United States)

    Qi, Pan; Shao, Wenbin; Liao, Shusheng

    2016-02-01

    For quantitative defects detection research on heat transfer tube in nuclear power plants (NPP), two parts of work are carried out based on the crack as the main research objects. (1) Production optimization of calibration tube. Firstly, ASME, RSEM and homemade crack calibration tubes are applied to quantitatively analyze the defects depth on other designed crack test tubes, and then the judgment with quantitative results under crack calibration tube with more accuracy is given. Base on that, weight analysis of influence factors for crack depth quantitative test such as crack orientation, length, volume and so on can be undertaken, which will optimize manufacture technology of calibration tubes. (2) Quantitative optimization of crack depth. Neural network model with multi-calibration curve adopted to optimize natural crack test depth generated in in-service tubes shows preliminary ability to improve quantitative accuracy.

  9. Assessing the Impact of Current National Policies to Reduce Salt ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Assessing the Impact of Current National Policies to Reduce Salt and Trans Fatty Acids in Argentina ... The Codex Alimentarius, or international food safety standards, will also decrease trans fatty acids (TFA) ... Researchers will develop a strategy to share results with policymakers and other stakeholders. ... Journal articles.

  10. Eddy current and quench loads and stress of SSC collider 4-K liner and the bore tube during magnet quench

    International Nuclear Information System (INIS)

    Leung, K.K.; Shu, Q.S.

    1993-07-01

    This paper describes the response of the eddy current and quench loads on a proposed Superconducting SuperCollider 4-K liner system. The liner within a bore tube is designed to remove the radiated power and the photodesorbed gas that impair the beam tube vacuum. The bimetallic liner tube is subjected to cooldown and eddy current loads. The square liner tube is a two-shell laminated Nitronic-40 steel is used for strength and a copper inner layer for low impedance to the image currents. Perforated holes are used to remove the photodesorbed gases for vacuum maintenance. The holes are located in a low-stress area of the liner. Rectangular holes in a four-pole symmetry pattern are required for beam dynamic stability. The liner is conductivity cooled by the round steel bore tube with a 2-mm wall. The copper layer must not be stressed over the yield strength limit because copper properties such as conductivity are known to change when the copper is stressed over yield strength. This analysis will address liner system response under thermal, eddy current, and vaporized liquid helium loads in a quenching dipole magnet

  11. Application of automatic tube current modulation with 64-detector CT in infant brain

    International Nuclear Information System (INIS)

    Li Jianming; Xu Wenbiao; Luo Yuanli; Liu Hongsheng; Zhou Ning

    2010-01-01

    Objective: To evaluate the effect of automatic tube modulation on imaging quality and lesion revealed in infant brain. Methods: The infant patients of 200 cases were divided into four groups according to the values of SD (2.5, 2.75, 3.0, 4.0), 50 cases in each group. They were performed with the automatic tube current modulation scanning in brain. The imaging quality and radiation dose were analyzed. Results: When the values of SD were 2.5, 2.75, 3.0 and 4.0, the high values of CTDI vol were 60.0, 49.8, 42.9 and 25.8 mGy, respectively. The effective doses were (3.27±1.01), (2.78±0.85), (2.40±0.74) and (1.49±0.45) mSv·mGy -1 ·cm -1 , respectively. There was significant difference among those groups (F=48.99, P<0.05). The excellent imaging qualities were 100%, 96%, 70% and 20%, 12 cases were neonate in SD 2.5 group. In SD 2.75 group, the imaging quality of neonate (2 cases) were all fine. In SD 3.0 group, the imaging quality was not ideal for the ages less than 1 year. In SD 4.0 group, when the infants aged over 2 years and 6 months, or with the larger head circumference, their imaging quality were all excellent. Conclusions: The individual application of ATCM could obtain the best balance among imaging quality, radiation dose and diagnostic quality. The SD 2.5, 2.75, 3.0 and 4.0 might be suitable to infants of newborn, 1 month to 1 year old, 1 to 3 years, the larger head circumference and part of the reviewed cases. (authors)

  12. Design options for reducing the impact of the fill-tube in ICF implosion experiments on the NIF

    Science.gov (United States)

    Weber, Christopher R.; Berzak Hopkins, L. F.; Casey, D. T.; Clark, D. S.; Hammel, B. A.; Le Pape, S.; Macphee, A.; Milovich, J.; Pickworth, L. A.; Robey, H. F.; Smalyuk, V. A.; Stadermann, M.; Felker, S. J.; Nikroo, A.; Thomas, C. A.; Crippen, J.; Rice, N.

    2017-10-01

    Inertial Confinement Fusion (ICF) capsules on the National Ignition Facility (NIF) are filled with thermonuclear fuel through a fill-tube. When the capsule implodes, perturbations caused by the fill-tube allow ablator material to mix into the hot spot and reduce fusion performance. This talk will explore several design options that attempt to reduce this damaging effect. Reducing the diameter of the fill-tube and its entrance hole is the obvious course and has been tested in experiments. Simulations also show sensitivity to the amount of glue holding the fill-tube to the capsule and suggest that careful control of this feature can limit the amount of injected mass. Finally, an off-axis fill-tube reduces the initial squirt of material into the fuel and may be a way of further optimizing this engineering feature. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  13. A standardized procedure for eddy-current testing of stainless steel, thin-walled nuclear fuel element cladding tubes

    International Nuclear Information System (INIS)

    Barat, P.; Raj, B.; Bhattacharya, D.K.

    1982-01-01

    Thin-walled nuclear fuel cladding tubes made of AISI 316 stainless steel have been examined by eddy-current testing. Standardization of the procedures has required investigations on optimizing the test frequency, finding a method to locate a defect with respect to the probe reference end, and the use of standard defects and sequential metallography of natural defects detected by eddy-current testing, to understand the influence of the nature of defects on the impedance output signals. Test frequency and method of locating the defect were optimized by the use of standard defects made by machining in reference cladding tubes. Subsequent metallography of natural defects detected by eddy-current testing revealed mainly clusters of inclusions but also other types of defects. The effect of the distribution of inclusions along the length of the tube on the impedance output is discussed. (author)

  14. Standardized procedure for eddy-current testing of stainless steel, thin-walled nuclear fuel element cladding tubes

    Energy Technology Data Exchange (ETDEWEB)

    Barat, P; Raj, B; Bhattacharya, D K [Reactor Research Centre, Kalpakkam (India)

    1982-10-01

    Thin-walled nuclear fuel cladding tubes made of AISI 316 stainless steel have been examined by eddy-current testing. Standardization of the procedures has required investigations on optimizing the test frequency, finding a method to locate a defect with respect to the probe reference end, and the use of standard defects and sequential metallography of natural defects detected by eddy-current testing, to understand the influence of the nature of defects on the impedance output signals. Test frequency and method of locating the defect were optimized by the use of standard defects made by machining in reference cladding tubes. Subsequent metallography of natural defects detected by eddy-current testing revealed mainly clusters of inclusions but also other types of defects. The effect of the distribution of inclusions along the length of the tube on the impedance output is discussed.

  15. Methods of evaluation of accuracy with multiple essential parameters for eddy current measurement of pressure tube to calandria tube gap in CANDU reactors

    Energy Technology Data Exchange (ETDEWEB)

    Shokralla, S., E-mail: shaddy.shokralla@opg.com [Ontario Power Generation, IMS NDE Projects, Ajax, Ontario (Canada); Krause, T.W., E-mail: thomas.krause@rmc.ca [Royal Military College of Canada, Kingston, Ontario (Canada)

    2014-01-15

    The purpose of inspection qualification of a particular inspection system is to show that it meets applicable inspection specification requirements. Often a requirement of the inspection system is that it meets a particular accuracy. In the case of a system with multiple inputs accompanied by additional influential parameters, calculation of the system's output accuracy can be formidable. Measurement of pressure-tube to calandria tube gap in CANDU reactors using an eddy current based technique is presented as a particular example of a system where multiple essential parameters combine to generate a final uncertainty for the inspection system. This paper outlines two possible methods of calculating such a system's accuracy, and discusses the advantages and disadvantages of each. (author)

  16. Prospective estimation of organ dose in CT under tube current modulation

    International Nuclear Information System (INIS)

    Tian, Xiaoyu; Li, Xiang; Segars, W. Paul; Frush, Donald P.; Samei, Ehsan

    2015-01-01

    Purpose: Computed tomography (CT) has been widely used worldwide as a tool for medical diagnosis and imaging. However, despite its significant clinical benefits, CT radiation dose at the population level has become a subject of public attention and concern. In this light, optimizing radiation dose has become a core responsibility for the CT community. As a fundamental step to manage and optimize dose, it may be beneficial to have accurate and prospective knowledge about the radiation dose for an individual patient. In this study, the authors developed a framework to prospectively estimate organ dose for chest and abdominopelvic CT exams under tube current modulation (TCM). Methods: The organ dose is mainly dependent on two key factors: patient anatomy and irradiation field. A prediction process was developed to accurately model both factors. To model the anatomical diversity and complexity in the patient population, the authors used a previously developed library of computational phantoms with broad distributions of sizes, ages, and genders. A selected clinical patient, represented by a computational phantom in the study, was optimally matched with another computational phantom in the library to obtain a representation of the patient’s anatomy. To model the irradiation field, a previously validated Monte Carlo program was used to model CT scanner systems. The tube current profiles were modeled using a ray-tracing program as previously reported that theoretically emulated the variability of modulation profiles from major CT machine manufacturers Li et al., [Phys. Med. Biol. 59, 4525–4548 (2014)]. The prediction of organ dose was achieved using the following process: (1) CTDI vol -normalized-organ dose coefficients (h organ ) for fixed tube current were first estimated as the prediction basis for the computational phantoms; (2) each computation phantom, regarded as a clinical patient, was optimally matched with one computational phantom in the library; (3) to

  17. Convolution-based estimation of organ dose in tube current modulated CT

    Science.gov (United States)

    Tian, Xiaoyu; Segars, W. Paul; Dixon, Robert L.; Samei, Ehsan

    2016-05-01

    Estimating organ dose for clinical patients requires accurate modeling of the patient anatomy and the dose field of the CT exam. The modeling of patient anatomy can be achieved using a library of representative computational phantoms (Samei et al 2014 Pediatr. Radiol. 44 460-7). The modeling of the dose field can be challenging for CT exams performed with a tube current modulation (TCM) technique. The purpose of this work was to effectively model the dose field for TCM exams using a convolution-based method. A framework was further proposed for prospective and retrospective organ dose estimation in clinical practice. The study included 60 adult patients (age range: 18-70 years, weight range: 60-180 kg). Patient-specific computational phantoms were generated based on patient CT image datasets. A previously validated Monte Carlo simulation program was used to model a clinical CT scanner (SOMATOM Definition Flash, Siemens Healthcare, Forchheim, Germany). A practical strategy was developed to achieve real-time organ dose estimation for a given clinical patient. CTDIvol-normalized organ dose coefficients ({{h}\\text{Organ}} ) under constant tube current were estimated and modeled as a function of patient size. Each clinical patient in the library was optimally matched to another computational phantom to obtain a representation of organ location/distribution. The patient organ distribution was convolved with a dose distribution profile to generate {{≤ft(\\text{CTD}{{\\text{I}}\\text{vol}}\\right)}\\text{organ, \\text{convolution}}} values that quantified the regional dose field for each organ. The organ dose was estimated by multiplying {{≤ft(\\text{CTD}{{\\text{I}}\\text{vol}}\\right)}\\text{organ, \\text{convolution}}} with the organ dose coefficients ({{h}\\text{Organ}} ). To validate the accuracy of this dose estimation technique, the organ dose of the original clinical patient was estimated using Monte Carlo program with TCM profiles explicitly modeled. The

  18. Low volume tubes are not effective to reduce the rate of hemolyzed specimens from the emergency department.

    Science.gov (United States)

    Lippi, Giuseppe; Bonelli, Patrizia; Graiani, Virna; Caleffi, Catia; Cervellin, Gianfranco

    2014-02-01

    Spurious hemolysis is the leading source of nonconformities that can be recorded in diagnostic samples, especially those collected in the emergency department (ED). The aim of this study was to assess whether the shift from regular to low volume blood collection tubes may reduce the rate of hemolysis in a large urban ED, where approximately 80% of blood collections are performed through catheters. In a former 5-month period, blood collection in the ED was performed using 5.0mL (13×100mm) plastic serum tubes, which were then completely replaced with 3.5mL (13×75mm) plastic serum tubes for another period of 5months. The rate of hemolyzed specimens (i.e., those containing a cell-free hemoglobin ≥0.5gL) collected in the two periods was compared by Fisher exact test. The rate of hemolyzed specimens received from the ED increased from 3.5% using 5.0mL plastic serum tubes to 5.2% after introduction of 3.5mL plastic serum tubes (p<0.001). The use of low volume tubes was not effective to decrease the hemolysis rate in a large urban ED. Copyright © 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  19. Special wrench for B-nuts reduces torque stress in tubing

    Science.gov (United States)

    Stein, J. A.

    1970-01-01

    Gear-driven torque wrench with bearing support is used to tighten B-nut connection of partially supported fluid line with minimum stress to adjacent tubing and fittings. Wrench is useful for working with weak or brittle lines such as glass tubing.

  20. Self-field AC losses and critical currents in multi-tube Ag-Bi-2223 conductors

    Energy Technology Data Exchange (ETDEWEB)

    Ciszek, M; Ashworth, S P; Campbell, A M [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); James, M P; Glowacki, B A [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Garre, R; Conti, S [Centro Ricerche Europa Metalli, Fornaci di Barga, LU (Italy)

    1996-05-01

    The purpose of this work was to investigate the influence of different technological treatments of silver sheathed Bi-2223 tapes on the critical current density and the AC transport losses. The tapes were produced using the 'tube-in-tube' technique, by including a silver rod in the centre of the superconducting powder during packing of the silver tube. The aim of the process is to increase the silver to superconductor surface area and thus also the alignment at the centre of the conductor ceramic core. AC transport losses were measured by means of an electrical method using sinusoidally varying currents in the frequency range 30-180 Hz. In this range the power losses are hysteretic. The measured variation in losses from those predicted by a critical state model is attributed to the complex geometry of superconducting regions existing in these tapes. (author)

  1. Lunar Lava Tube Sensing

    Science.gov (United States)

    York, Cheryl Lynn; Walden, Bryce; Billings, Thomas L.; Reeder, P. Douglas

    1992-01-01

    Large (greater than 300 m diameter) lava tube caverns appear to exist on the Moon and could provide substantial safety and cost benefits for lunar bases. Over 40 m of basalt and regolith constitute the lava tube roof and would protect both construction and operations. Constant temperatures of -20 C reduce thermal stress on structures and machines. Base designs need not incorporate heavy shielding, so lightweight materials can be used and construction can be expedited. Identification and characterization of lava tube caverns can be incorporated into current precursor lunar mission plans. Some searches can even be done from Earth. Specific recommendations for lunar lava tube search and exploration are (1) an Earth-based radar interferometer, (2) an Earth-penetrating radar (EPR) orbiter, (3) kinetic penetrators for lunar lava tube confirmation, (4) a 'Moon Bat' hovering rocket vehicle, and (5) the use of other proposed landers and orbiters to help find lunar lava tubes.

  2. The effect of angular and longitudinal tube current modulations on the estimation of organ and effective doses in x-ray computed tomography

    International Nuclear Information System (INIS)

    Straten, Marcel van; Deak, Paul; Shrimpton, Paul C.; Kalender, Willi A.

    2009-01-01

    Purpose: Tube current modulation (TCM) is one of the recent developments in multislice CT that has proven to reduce the patient radiation dose without affecting the image quality. Presently established methods and published coefficients for estimating organ doses from the dose measured free in air on the axis of rotation or in the CT dose index (CTDI) dosimetry phantoms do not take into account this relatively new development in CT scanner design and technology. Based on these organ dose coefficients effective dose estimates can be made. The estimates are not strictly valid for CT scanning protocols utilizing TCM. In this study, the authors investigated the need to take TCM into account when estimating organ and effective dose values. Methods: A whole-body adult anthropomorphic phantom (Alderson Rando) was scanned with a multislice CT scanner (Somatom Definition, Siemens, Forchheim, Germany) utilizing TCM (CareDose4D). Tube voltage was 120 kV, beam collimation 19.2 mm, and pitch 1. A voxelized patient model was used to define the tissues and organs in the phantom. Tube current values as a function of tube angle were obtained from the raw data for each individual tube rotation of the scan. These values were used together with the Monte Carlo dosimetry tool IMPACTMC (VAMP GmbH, Erlangen, Germany) to calculate organ dose values both with and without account of TCM. Angular and longitudinal modulations were investigated separately. Finally, corresponding effective dose conversion coefficients were determined for both cases according to the updated 2007 recommendations of the ICRP. Results: TCM amplitude was greatest in the shoulder and pelvic regions. Consequently, dose distributions and organ dose values for particular cross sections changed considerably when taking angular modulation into account. The effective dose conversion coefficients were up to 11% lower for a single rotation in the shoulder region and 17% lower in the pelvis when taking angular TCM into

  3. Expert system for eddy current signal analysis: non destructive testing of steam generator tubings

    International Nuclear Information System (INIS)

    Benoist, B.

    1991-01-01

    Automatic analysis, by computer, of defect signals in steam generator tubes, based on Eddy current multifrequency technique, is must often inefficient due to pilgrim noise. The first step is to use a method that allows us to eleminate the noise: the adaptative interpolation. Thanks to this method, which ensures reliable data on each channel, the analysis can be realised by taking into account the data corresponding to each basic or mixed channel. By correlating these diverse data, we can class the signals according to two types of defects: single defects (symmetrical), multiple defects (several in the same place). The second step is to use an expert system which allows a reliable diagnosis for whatever family the defect belongs to. According to this classification, analysis is continued and results in the characterization of the defect. The expert system has already been developed with the general purpose application expert system shell SUPER, which is briefly described. The knowledge base (SOCRATE) and the specific tools developed for this application are thoroughly described. The first results obtained with signals corresponding to real defects, that have been recorded in different places, are presented and discussed. The expert system is revealed efficient in all the studied cases, even with signals obtained in very noisy environments [fr

  4. An overview of current developments in position-sensitive hybrid photon detectors and photo-multiplier tubes

    CERN Document Server

    Gys, Thierry

    1999-01-01

    Current developments in position-sensitive hybrid photon detectors and photo-multiplier tubes have stimulated increased interest from a variety of fields such as astronomy, biomedical imaging and high- energy physics. These devices are sensitive to single photons over a photon energy spectrum defined by the transmission of the optical entrance window and the photo-cathode type. Their spatial resolution ranges from a few millimeters for pad hybrid photon detectors and multi-anode photo-multiplier tubes down to a few tens of microns for pixel hybrid photon detectors and electron-bombarded charge-coupled devices. Basic technological and design aspects are assessed in this paper. (21 refs).

  5. In service inspection of steam generator tubes with a multifrequence eddy current apparatus

    International Nuclear Information System (INIS)

    Pigeon, M.; Saglio, R.

    1976-01-01

    The described multifrequency device has been designed and developed for a complete testing of tubes. It is necessary to eliminate the signals given by plates, expanded parts, background noises and magnetic signals which can mask some possible defects [fr

  6. Combination of U.V.-B and ozone reduces pollen tube growth more than either stress alone

    International Nuclear Information System (INIS)

    Feder, W.A.; Shrier, R.

    1990-01-01

    The rate of in vitro Nicotiana tabacum L. “Bel-W3” pollen tube growth was reduced 62 and 44%, respectively, when pollen tubes were exposed to 120 ppb ozone (O 3 ) for 3 hr or 300 μW/cm 2 ultraviolet-B (u.v.-B) radiation for 30 min. Petunia hybrida Vilm. “White Cascade” pollen tube growth was reduced 34 and 59%, respectively, upon exposure to O 3 or u.v.-B at the above doses. The combination of u.v.-B at 300 μW/cm 2 for 30 min, followed by O 3 at 120 ppb for 3 hr, reduced pollen tube growth by 79% for “Bel-W3” and 75% for “White Cascade”. The effect appeared to be additive, implying that different target areas may be affected by the two stressors. In the Northeast, plants are exposed to both u.v.-B and O 3 during the normal growing season. This may result in an unexpectedly higher stress on the reproductive system than had been previously suspected based on these two stressors acting individually. (author)

  7. Eddy Currents Inspection of CANDU Steam Generator Tubes using Zetec's ZR-1 Robot. Experience in Romania

    Energy Technology Data Exchange (ETDEWEB)

    Scott Hower [Zetec Inc. (Romania); Luiza Vladu; Adrian Nichisov; Mihai Cretu [COMPCONTROL ING. (Romania)

    2006-07-01

    Full text of publication follows: The commercial operation of Unit 1 of Cernavoda NPP started on 2 December, 1996. The unit's reactor type is PHWR-CANDU 6 (electrical capacity 706 MWe), using natural uranium. The nuclear fuel is manufactured in Romania. The Cernavoda nuclear power plant has four CANDU - design steam generators that have been in service since 1996. The paper introduces the new ZR-1 Robot System for Inspection and Maintenance/Repair from Zetec that combines the newest state-of-the-art robotics technology with Zetec experience - based innovation to address the needs for inspection and repair of steam generators. The multipurpose ZR-1 can be easily installed to perform the necessary eddy current inspection and remain installed ready for follow-up maintenance and repair. It has superior technical performances and a modular three axis motion of arm that enables 100% coverage of tube sheet. Automated, repeatable, and precise positioning of tool heads ensures accurate delivery and reducing costly rework and reduces inspection time by 30%. The modular, light weight, and portable design permits easy assembly and disassembly through small openings and it reduces setup/tear down time by 30%. The first deployment of the new ZR-1 Robot was made in September 2004 at the Cernavoda NPP inspection outage. The unit's reactor type is PHWR-CANDU 6 (electrical capacity 706 MWe), using natural uranium; the nuclear fuel is manufactured in Romania. The Cernavoda nuclear power plant Unit 1 has four CANDU - design steam generators that have been in service since 1996. The paper presents also the Zetec's field experience and customer experience with this system. It describes the equipment setup in Cernavoda's steam generators mock-up, functional tests and calibration. Finally, provides details on the execution of the inspection, options for standardizing the inspection techniques and conclusions. (authors)

  8. Determination of semi-reducing layer and applied stress through spectra emitted by an X-ray tube

    International Nuclear Information System (INIS)

    Santos, Josilene C.; Gonzalez, Alejandro H.L.; Terini, Ricardo A.; Costa, Paulo R.

    2016-01-01

    This work describes a method for assessment of half value layer (HVL) and peak tube voltage (kVp) by means of experimental x-ray spectra measured using a CdTe detector. The work also evaluated spectrometry parameters such as dead time and count rate, and x-ray tube characteristics that can affect the assessment of these quantities. Two sets of x-ray spectra were measured: A) using Cu filters with different thicknesses and fixed tube current, and B) keeping a fixed Cu filtration and different tube current and, so, ranging the count rates. The spectrometer was energy calibrated using standard radioactive sources. kVp value was estimated by means of experimental measured x-ray spectra, using linear regression in order to search the end point of each spectrum. HVL was estimated after the correction of the measured spectra, using an analytical method implemented using Matlab® software. For comparison, HVL was also determined using a 30 cm"3 ion chamber and high purity Al filters. (author)

  9. Evaluation of the individual tube current setting in electrocardiogram-gated cardiac computed tomography estimated from plain chest computed tomography using computed tomography automatic exposure control

    International Nuclear Information System (INIS)

    Kishimoto, Junichi; Sakou, Toshio; Ohta, Yasutoshi

    2013-01-01

    The aim of this study was to estimate the tube current on a cardiac computed tomography (CT) from a plain chest CT using CT-automatic exposure control (CT-AEC), to obtain consistent image noise, and to optimize the scan tube current by individualizing the tube current. Sixty-five patients (Group A) underwent cardiac CT at fixed tube current. The mAs value for plain chest CT using CT-AEC (AEC value) and cardiac CT image noise were measured. The tube current needed to obtain the intended level of image noise in the cardiac CT was determined from their correlation. Another 65 patients (Group B) underwent cardiac CT with tube currents individually determined from the AEC value. Image noise was compared among Group A and B. Image noise of cardiac CT in Group B was 24.4±3.1 Hounsfield unit (HU) and was more uniform than in Group A (21.2±6.1 HU). The error with the desired image noise of 25 HU was lower in Group B (2.4%) than in Group A (15.2%). Individualized tube current selection based on AEC value thus provided consistent image noise and a scan tube current optimized for cardiac CT. (author)

  10. Combining automatic tube current modulation with adaptive statistical iterative reconstruction for low-dose chest CT screening.

    Directory of Open Access Journals (Sweden)

    Jiang-Hong Chen

    Full Text Available To reduce radiation dose while maintaining image quality in low-dose chest computed tomography (CT by combining adaptive statistical iterative reconstruction (ASIR and automatic tube current modulation (ATCM.Patients undergoing cancer screening (n = 200 were subjected to 64-slice multidetector chest CT scanning with ASIR and ATCM. Patients were divided into groups 1, 2, 3, and 4 (n = 50 each, with a noise index (NI of 15, 20, 30, and 40, respectively. Each image set was reconstructed with 4 ASIR levels (0% ASIR, 30% ASIR, 50% ASIR, and 80% ASIR in each group. Two radiologists assessed subjective image noise, image artifacts, and visibility of the anatomical structures. Objective image noise and signal-to-noise ratio (SNR were measured, and effective dose (ED was recorded.Increased NI was associated with increased subjective and objective image noise results (P<0.001, and SNR decreased with increasing NI (P<0.001. These values improved with increased ASIR levels (P<0.001. Images from all 4 groups were clinically diagnosable. Images with NI = 30 and 50% ASIR had average subjective image noise scores and nearly average anatomical structure visibility scores, with a mean objective image noise of 23.42 HU. The EDs for groups 1, 2, 3 and 4 were 2.79 ± 1.17, 1.69 ± 0.59, 0.74 ± 0.29, and 0.37 ± 0.22 mSv, respectively. Compared to group 1 (NI = 15, the ED reductions were 39.43%, 73.48%, and 86.74% for groups 2, 3, and 4, respectively.Using NI = 30 with 50% ASIR in the chest CT protocol, we obtained average or above-average image quality but a reduced ED.

  11. Combining automatic tube current modulation with adaptive statistical iterative reconstruction for low-dose chest CT screening.

    Science.gov (United States)

    Chen, Jiang-Hong; Jin, Er-Hu; He, Wen; Zhao, Li-Qin

    2014-01-01

    To reduce radiation dose while maintaining image quality in low-dose chest computed tomography (CT) by combining adaptive statistical iterative reconstruction (ASIR) and automatic tube current modulation (ATCM). Patients undergoing cancer screening (n = 200) were subjected to 64-slice multidetector chest CT scanning with ASIR and ATCM. Patients were divided into groups 1, 2, 3, and 4 (n = 50 each), with a noise index (NI) of 15, 20, 30, and 40, respectively. Each image set was reconstructed with 4 ASIR levels (0% ASIR, 30% ASIR, 50% ASIR, and 80% ASIR) in each group. Two radiologists assessed subjective image noise, image artifacts, and visibility of the anatomical structures. Objective image noise and signal-to-noise ratio (SNR) were measured, and effective dose (ED) was recorded. Increased NI was associated with increased subjective and objective image noise results (PASIR levels (PASIR had average subjective image noise scores and nearly average anatomical structure visibility scores, with a mean objective image noise of 23.42 HU. The EDs for groups 1, 2, 3 and 4 were 2.79 ± 1.17, 1.69 ± 0.59, 0.74 ± 0.29, and 0.37 ± 0.22 mSv, respectively. Compared to group 1 (NI = 15), the ED reductions were 39.43%, 73.48%, and 86.74% for groups 2, 3, and 4, respectively. Using NI = 30 with 50% ASIR in the chest CT protocol, we obtained average or above-average image quality but a reduced ED.

  12. Improvement of Eddy Current testing methods of steam generator tubings due to field experience

    International Nuclear Information System (INIS)

    Comby, R.; Meurgey, P.; David, B.

    1985-01-01

    This paper presents the main stages of the long rotating probe developed by EDF, this probe detects stress corrosion cracks. The method has been validated by the examination of numerous cracked tubes that the probe detected before. Methods to better characterize the signals with regard to the defects are being improved to avoid a complementary examination of the rolling zone more particularly [fr

  13. Grow tubes reduce root and crown growth but not early production during establishment of highbush blueberry

    Science.gov (United States)

    In blueberry, grow tubes have been used by some growers to establish new plantings and to replace plants within older plantings. We conducted two experiments at a commercial northern highbush blueberry (Vaccinium corymbosum L.) farm over three years using four cultivars (Aurora, Elliott, Liberty, Oz...

  14. Mechanics of neurulation: From classical to current perspectives on the physical mechanics that shape, fold, and form the neural tube.

    Science.gov (United States)

    Vijayraghavan, Deepthi S; Davidson, Lance A

    2017-01-30

    Neural tube defects arise from mechanical failures in the process of neurulation. At the most fundamental level, formation of the neural tube relies on coordinated, complex tissue movements that mechanically transform the flat neural epithelium into a lumenized epithelial tube (Davidson, 2012). The nature of this mechanical transformation has mystified embryologists, geneticists, and clinicians for more than 100 years. Early embryologists pondered the physical mechanisms that guide this transformation. Detailed observations of cell and tissue movements as well as experimental embryological manipulations allowed researchers to generate and test elementary hypotheses of the intrinsic and extrinsic forces acting on the neural tissue. Current research has turned toward understanding the molecular mechanisms underlying neurulation. Genetic and molecular perturbation have identified a multitude of subcellular components that correlate with cell behaviors and tissue movements during neural tube formation. In this review, we focus on methods and conceptual frameworks that have been applied to the study of amphibian neurulation that can be used to determine how molecular and physical mechanisms are integrated and responsible for neurulation. We will describe how qualitative descriptions and quantitative measurements of strain, force generation, and tissue material properties as well as simulations can be used to understand how embryos use morphogenetic programs to drive neurulation. Birth Defects Research 109:153-168, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  15. Estimating patient dose from CT exams that use automatic exposure control: Development and validation of methods to accurately estimate tube current values.

    Science.gov (United States)

    McMillan, Kyle; Bostani, Maryam; Cagnon, Christopher H; Yu, Lifeng; Leng, Shuai; McCollough, Cynthia H; McNitt-Gray, Michael F

    2017-08-01

    The vast majority of body CT exams are performed with automatic exposure control (AEC), which adapts the mean tube current to the patient size and modulates the tube current either angularly, longitudinally or both. However, most radiation dose estimation tools are based on fixed tube current scans. Accurate estimates of patient dose from AEC scans require knowledge of the tube current values, which is usually unavailable. The purpose of this work was to develop and validate methods to accurately estimate the tube current values prescribed by one manufacturer's AEC system to enable accurate estimates of patient dose. Methods were developed that took into account available patient attenuation information, user selected image quality reference parameters and x-ray system limits to estimate tube current values for patient scans. Methods consistent with AAPM Report 220 were developed that used patient attenuation data that were: (a) supplied by the manufacturer in the CT localizer radiograph and (b) based on a simulated CT localizer radiograph derived from image data. For comparison, actual tube current values were extracted from the projection data of each patient. Validation of each approach was based on data collected from 40 pediatric and adult patients who received clinically indicated chest (n = 20) and abdomen/pelvis (n = 20) scans on a 64 slice multidetector row CT (Sensation 64, Siemens Healthcare, Forchheim, Germany). For each patient dataset, the following were collected with Institutional Review Board (IRB) approval: (a) projection data containing actual tube current values at each projection view, (b) CT localizer radiograph (topogram) and (c) reconstructed image data. Tube current values were estimated based on the actual topogram (actual-topo) as well as the simulated topogram based on image data (sim-topo). Each of these was compared to the actual tube current values from the patient scan. In addition, to assess the accuracy of each method in estimating

  16. On Eddy current examination (ECE) of Incoloy 800 SG tube using OD encircling and ID bobbin coil

    International Nuclear Information System (INIS)

    Kapoor, K.; Sunder Krishna, K.; Bakshu, S.A.

    2015-01-01

    The purpose of this paper is to present and compare the results of ECE carried out on steam generator tubes from OD side and ID side. During the manufacturing of the tubes Eddy current testing is being carried out using OD encircling probe as per ASTM E 571. Here the purpose of the test is to capture the manufacturing defects. The parameters of the test are optimized to achieve best sensitivity to this requirement. These tubes are then installed in the steam generator and once again ECE is carried out during installation (pre-service inspection-PSI) and during in-service inspection (ISI) by using ID bobbin coil. These tests are carried out as per ASME section V article 8 appendix 1. Here the purpose of the test is to detect wall thinning, dent, pits etc due to operation and to locate these defects (OD side or ID side). Here the operating parameters are optimized for phase separation of defects from OD and ID. These parameters are quite different from those used during the manufacturing ECE. Interpretation of the signals detected in PSI/ISI in must be done with care to correlate with defect indications detected during manufacturing. In the present study, tubes with certain manufacturing defects, detected with OD encircling test were subjected to ID bobbin coil examination. Also certain tubes with signal picked up during test from ID were examined by using the OD encircling probe. This comparison of the results provides a clear picture about the sensitivity and deficiency of the either type of test. (author)

  17. review of current evidence for folate in the prevention of neural tube ...

    African Journals Online (AJOL)

    The incidence of neural tube defects (NTD) among black South. Africans living in urban areas is low compared with reports of _". I\\TTD incidence in rural areasY A NTD incidence of 0.95 per -;:-. 1000 live births was reported in Cape Town,l while an incidence of 0.99 per 1 000 live births was reported in a study performed at ...

  18. Ambulatory anesthetic care in children undergoing myringotomy and tube placement: current perspectives

    OpenAIRE

    Robinson H; Engelhardt T

    2017-01-01

    Hal Robinson, Thomas Engelhardt Department of Anaesthesia, Royal Aberdeen Children’s Hospital, Aberdeen, UK Purpose: Myringotomy and tube placement is one of the most frequently performed ear, nose and throat (ENT) surgeries in the pediatric population. Effective anesthetic management is vital to ensuring successful ambulatory care and ensuring child and parental satisfaction.Recent findings: This review summarizes recently published studies about the long-term effects of g...

  19. Design and array signal suggestion of array type pulsed eddy current probe for health monitoring of metal tubes

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Young Kil [Dept. of Electrical Engineering, Kunsan National University, Kunsan (Korea, Republic of)

    2015-10-15

    An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

  20. Numerical simulations of eddy current testing signals of steam generator tubes by 3-D finite element method

    International Nuclear Information System (INIS)

    Sakai, Takayuki; Soneda, Naoki

    1996-01-01

    In every inspection of Japanese PWR plants, all of steam generator tubes are inspected using Eddy Current Testing (ECT) method. However, the relationships between the ECT signals and the defect shapes are known only for the representative shapes of defects. In order to improve the reliability of inspections and the capability of ECT probes, development of numerical simulation technique of the ECT signals for arbitrarily shaped defects is essential. In this study, three-dimensional finite element code is developed to simulate the ECT signals for any kinds of defects in the SG tubes. The code is fully vectorized so that it runs on the supercomputers very efficiently. The simulation results agree very well with the experimental results. Sensitivity analyses are performed to investigate the relationships between the defect shapes and the ECT signals. (author)

  1. Angular detector of defects in a metallic tube by eddy currents

    International Nuclear Information System (INIS)

    Broudeur, R.

    1990-01-01

    The angular detector of defects in a metallic tube has two centering pieces for the clad positioning on both sides of a backing ring of the measuring coil. The inner diameter of the backing ring and the diameter of the centering pieces are in the ratio 4/3±0.6/3 and their axis are eccentric. This setting over associated at the guiding piece of the sheath in rotation gives at the measuring coil a functioning as a ponctual probe [fr

  2. Identifying Measures Used for Assessing Quality of YouTube Videos with Patient Health Information: A Review of Current Literature.

    Science.gov (United States)

    Gabarron, Elia; Fernandez-Luque, Luis; Armayones, Manuel; Lau, Annie Ys

    2013-02-28

    Recent publications on YouTube have advocated its potential for patient education. However, a reliable description of what could be considered quality information for patient education on YouTube is missing. To identify topics associated with the concept of quality information for patient education on YouTube in the scientific literature. A literature review was performed in MEDLINE, ISI Web of Knowledge, Scopus, and PsychINFO. Abstract selection was first conducted by two independent reviewers; discrepancies were discussed in a second abstract review with two additional independent reviewers. Full text of selected papers were analyzed looking for concepts, definitions, and topics used by its authors that focused on the quality of information on YouTube for patient education. In total, 456 abstracts were extracted and 13 papers meeting eligibility criteria were analyzed. Concepts identified related to quality of information for patient education are categorized as expert-driven, popularity-driven, or heuristic-driven measures. These include (in descending order): (1) quality of content in 10/13 (77%), (2) view count in 9/13 (69%), (3) health professional opinion in 8/13 (62%), (4) adequate length or duration in 6/13 (46%), (5) public ratings in 5/13 (39%), (6) adequate title, tags, and description in 5/13 (39%), (7) good description or a comprehensive narrative in 4/13 (31%), (8) evidence-based practices included in video in 4/13 (31%), (9) suitability as a teaching tool in 4/13 (31%), (10) technical quality in 4/13 (31%), (11) credentials provided in video in 4/13 (31%), (12) enough amount of content to identify its objective in 3/13 (23%), and (13) viewership share in 2/13 (15%). Our review confirms that the current topics linked to quality of information for patient education on YouTube are unclear and not standardized. Although expert-driven, popularity-driven, or heuristic-driven measures are used as proxies to estimate the quality of video information

  3. Nondestructive inspection of the tubes of TRIGA IPR-R1 reactor heat exchanger by eddy current testing

    International Nuclear Information System (INIS)

    Silva Junior, Silverio F.; Silva, Roger F.; Oliveira, Paulo F.; Barreto, Erika S.; Ribeiro, Isabela G.; Fraiz, Felipe C.

    2013-01-01

    The IPR-R1 TRIGA MARK 1 reactor is an open pool type reactor, cooled light water. It is used for research activities, personnel training and radioisotopes production, in operation since 1960 at the Nuclear Technology Development Center - CDTN/CNEN. It operates at a maximum thermal power of 100 kW and usually, the fuel cooling is done by natural circulation. If necessary, an external auxiliary cooling system, with a shell-and-tube type heat exchanger, can be used to improve the water heat removal. As part of the ageing management program of the reactor, a nondestructive evaluation of their heat exchanger stainless steel tubes will be performed, in order to verify its integrity. The examinations will be performed using the eddy current test method, which allows the detection and characterization of structural discontinuities in the wall of the tubes, if existing. For this purpose, probes and reference standards were designed and manufactured at CDTN facilities and test procedures were established and validated. In this paper, a description of the proposed infrastructure as well as the test methodology to be used in the examinations are presented and discussed. (author)

  4. Design Improvement of an X-ray Tube Applicator to Reduce ORE

    International Nuclear Information System (INIS)

    Lee, Juhyuk; Kim, Hyun Nam; Park, Han Beom; Cho, Sung Oh

    2017-01-01

    Radiation therapy has many advantages to treat cancer relative to other therapies. It does not induce scar or hair loss, and could can cover larger area than others. However, one the most critical issues about radiation therapy is shielding. Not only unnecessary exposure to patients but also those to doctors or nurses who participate in the treatment have to be lowered as possible. Occupational radiation exposure (ORE) is limited to 50 mSv per year by NCRP's recommendation. In this study, MC simulations were performed to evaluate the effective dose induced by the miniature x-ray tube. It was confirmed that when the applicator is adopted to the tube, the effective dose to doctor is less than the occupational radiation exposure limit recommended by ICRP. All assumptions used in this calculation were too highly conservative enough to have reliability. However some limitations still exist; for example, the more accurate results could be obtained if most recent version of conversion factors was used or we specified the organs irradiated and weighted the values by the radiation sensitivity.

  5. Low-dose respiratory-gated PET/CT: based on 30 mA tube current

    International Nuclear Information System (INIS)

    Wu Ping; Li Sijin; Zhang Yanlan; Hao Xinzhong; Qin Zhixing; Yan Min; Cheng Pengliang; Wu Zhifang

    2013-01-01

    Objective: To establish a low-dose but image-comparable respiratory-gated PET/CT (RG PET/CT) protocol based on 30 mA tube current plus other improved scanning parameters, such as the tube current, the number of respiratory phase and length of breathing cycle. Methods: Twenty-six patients with 18 F-FDG-intaking lung nodules underwent one-bed standard-dose PET/CT (120 mA, 2 min/bed) and low dose RG PET/CT (30 mA, 6 respiratory phases, 1 min/phase). The radiation dose and image quality were analyzed subsequently with signal to noise ratio (SNR) for PET and the homogeneity, noise level for CT in the water phantom respectively. Otherwise the CT images were both visual evaluated by two experienced doctors. In addition, different respiratory cycle was simulated to observe its relation with radiation dose. Results: The effective dose of low-dose RG PET/CT was 4.88∼7.69 mSv [mean (5.68±0.83) mSv]. The PET SNR showed no significance between groups. The homogeneity of 30 mA is good (< 5 HU), although noise level was high, the visual character like lobulation, speculation of lung nodule was superior in some respiratory phases. The radiation dose was positively correlated with respiratory cycle. Conclusions: The performance of low-dose RG PET/CT was comparable to those of standard-dose PET/CT based on a protocol with 30 mA tube current, 6 respiratory phases and breathing state of eupnoea. It produced a much lower radiation exposure and the image quality was enough for clinical use such as delineation of tumor active target, characterization and staging of lung nodules, etc. (authors)

  6. Efficacy of plastic mesh tubes in reducing herbivory damage by the invasive nutria (Myocastor coypus) in an urban restoration site

    Science.gov (United States)

    Sheffels, Trevor R.; Systma, Mark D.; Carter, Jacoby; Taylor, Jimmy D.

    2014-01-01

    The restoration of stream corridors is becoming an increasingly important component of urban landscape planning, and the high cost of these projects necessitates the need to understand and address potential ecological obstacles to project success. The nutria(Myocastor coypus) is an invasive, semi-aquatic rodent native to South America that causes detrimental ecological impacts in riparian and wetland habitats throughout its introduced range, and techniques are needed to reduce nutria herbivory damage to urban stream restoration projects. We assessed the efficacy of standard Vexar® plastic mesh tubes in reducing nutria herbivory damage to newly established woody plants. The study was conducted in winter-spring 2009 at Delta Ponds, a 60-ha urban waterway in Eugene, Oregon. Woody plants protected by Vexar® tubes demonstrated 100% survival over the 3-month initial establishment period, while only 17% of unprotected plantings survived. Nutria demonstrated a preference for black cottonwood (Populus balsamifera ssp trichocarpa) over red osier dogwood (Cornussericea) and willow (Salix spp). Camera surveillance showed that nutria were more active in unprotected rather than protected treatments. Our results suggest that Vexar® plastic mesh tubing can be an effective short-term herbivory mitigation tool when habitat use by nutria is low. Additionally, planting functionally equivalent woody plant species that are less preferred by nutria, and other herbivores, may be another method for reducing herbivory and improving revegetation success. This study highlights the need to address potential wildlife damage conflicts in the planning process for stream restoration in urban landscapes.

  7. Reducing consumption of electric current and energy carriers. [USSR

    Energy Technology Data Exchange (ETDEWEB)

    Ruppo, A.S.; Gruzdev, Yu.M.

    1985-01-01

    Evaluates the energy conservation program developed by the Giproshakht research institute is evaluated. The program was used in the Afanas'evo hydraulic mine in the Tulaugol association (with annual coal output of 2.1 Mt). Energy conservation program consisted of 2 groups of tasks: reducing energy consumption of the mine, and reducing energy consumption during the maximum demand hours in the morning and evening. The following methods were used: reducing idle running of chain and belt conveyors, separate draining of mine water free of dust and rock particles (reducing range of water cleaning), use of automatic control systems for mine blowers, automatic control of the system for coal drying, more efficient use of coal and materials transport in the mine. Energy demand of the mine during peak demand hours was reduced by adjusting fluctuations of energy consumption of the mine to fluctuations of energy demand in the power system of the area, e.g. by reducing mine draining in the morning and evening and operating at full capacity during the time of reduced energy demand. Using the energy conservation measures economized 4,324,300 kWh electric energy annually.

  8. Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing-Lei, E-mail: lijinglei80@126.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Huang, Mei-Ping, E-mail: huang_meiping@yahoo.com.cn [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liang, Chang-Hong, E-mail: cjr.lchh@vip.163.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhao, Zhen-Jun, E-mail: junabc2006@hotmail.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Hui, E-mail: liuhuijiujiu@gmail.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Cui, Yan-Hai, E-mail: yanhai_cui@126.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Qi-Shun, E-mail: liuqishun@yeah.net [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhang, Jin-E., E-mail: zhjine@yahoo.com.cn [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Yang, Lin, E-mail: yanglin001517@163.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Ivanc, Thomas B., E-mail: Thomas.ivanc@philips.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States); Yanof, Jeffrey H., E-mail: Jeffrey.yanof@philips.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States)

    2012-11-15

    Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R{sup 2} = 0.603). Effective radiation dose was reduced from 16.6 {+-} 0.9 to 9.8 {+-} 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

  9. Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection

    International Nuclear Information System (INIS)

    Li, Jing-Lei; Huang, Mei-Ping; Liang, Chang-Hong; Zhao, Zhen-Jun; Liu, Hui; Cui, Yan-Hai; Liu, Qi-Shun; Zhang, Jin-E.; Yang, Lin; Ivanc, Thomas B.; Yanof, Jeffrey H.

    2012-01-01

    Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R 2 = 0.603). Effective radiation dose was reduced from 16.6 ± 0.9 to 9.8 ± 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

  10. Real time flaw detection and characterization in tube through partial least squares and SVR: Application to eddy current testing

    Science.gov (United States)

    Ahmed, Shamim; Miorelli, Roberto; Calmon, Pierre; Anselmi, Nicola; Salucci, Marco

    2018-04-01

    This paper describes Learning-By-Examples (LBE) technique for performing quasi real time flaw localization and characterization within a conductive tube based on Eddy Current Testing (ECT) signals. Within the framework of LBE, the combination of full-factorial (i.e., GRID) sampling and Partial Least Squares (PLS) feature extraction (i.e., GRID-PLS) techniques are applied for generating a suitable training set in offine phase. Support Vector Regression (SVR) is utilized for model development and inversion during offine and online phases, respectively. The performance and robustness of the proposed GIRD-PLS/SVR strategy on noisy test set is evaluated and compared with standard GRID/SVR approach.

  11. Hypoglossal-facial nerve reconstruction using a Y-tube-conduit reduces aberrant synkinetic movements of the orbicularis oculi and vibrissal muscles in rats.

    Science.gov (United States)

    Kaya, Yasemin; Ozsoy, Umut; Turhan, Murat; Angelov, Doychin N; Sarikcioglu, Levent

    2014-01-01

    The facial nerve is the most frequently damaged nerve in head and neck trauma. Patients undergoing facial nerve reconstruction often complain about disturbing abnormal synkinetic movements of the facial muscles (mass movements, synkinesis) which are thought to result from misguided collateral branching of regenerating motor axons and reinnervation of inappropriate muscles. Here, we examined whether use of an aorta Y-tube conduit during reconstructive surgery after facial nerve injury reduces synkinesis of orbicularis oris (blink reflex) and vibrissal (whisking) musculature. The abdominal aorta plus its bifurcation was harvested (N = 12) for Y-tube conduits. Animal groups comprised intact animals (Group 1), those receiving hypoglossal-facial nerve end-to-end coaptation alone (HFA; Group 2), and those receiving hypoglossal-facial nerve reconstruction using a Y-tube (HFA-Y-tube, Group 3). Videotape motion analysis at 4 months showed that HFA-Y-tube group showed a reduced synkinesis of eyelid and whisker movements compared to HFA alone.

  12. Development of intelligent Eddy Current Testing (ECT) system for PWR steam generator tube inspection

    International Nuclear Information System (INIS)

    Kawata, K.; Kawase, N.; Kurokawa, M.; Asada, Y.

    2005-01-01

    The intelligent ECT system was developed for the inspection of heat transfer tubes of the steam generator of the PWR plant. It consists of intelligent probe, data acquisition unit and data analysis system. The probe combines 24 channels inclined lay out drive coils and thin film pick-up coils with built-in electric circuits to provide high inspection capability equivalent to rotating coil ECT and high-speed inspection equivalent to conventional bobbin coil ECT. The advanced data analysis system that has filtering and automatic analysis functions is also developed to enable fast and precise analysis of large volume inspection data. The system was qualified by confirmation tests in FY 2003 to show thinned thickness sizing accuracy within ± 5%. (T. Tanaka)

  13. Reducing hospital readmission rates: current strategies and future directions.

    Science.gov (United States)

    Kripalani, Sunil; Theobald, Cecelia N; Anctil, Beth; Vasilevskis, Eduard E

    2014-01-01

    New financial penalties for institutions with high readmission rates have intensified efforts to reduce rehospitalization. Several interventions that involve multiple components (e.g., patient needs assessment, medication reconciliation, patient education, arranging timely outpatient appointments, and providing telephone follow-up) have successfully reduced readmission rates for patients discharged to home. The effect of interventions on readmission rates is related to the number of components implemented; single-component interventions are unlikely to reduce readmissions significantly. For patients discharged to postacute care facilities, multicomponent interventions have reduced readmissions through enhanced communication, medication safety, advanced care planning, and enhanced training to manage medical conditions that commonly precipitate readmission. To help hospitals direct resources and services to patients with greater likelihood of readmission, risk-stratification methods are available. Future work should better define the roles of home-based services, information technology, mental health care, caregiver support, community partnerships, and new transitional care personnel.

  14. Ambulatory anesthetic care in children undergoing myringotomy and tube placement: current perspectives

    Directory of Open Access Journals (Sweden)

    Robinson H

    2017-04-01

    Full Text Available Hal Robinson, Thomas Engelhardt Department of Anaesthesia, Royal Aberdeen Children’s Hospital, Aberdeen, UK Purpose: Myringotomy and tube placement is one of the most frequently performed ear, nose and throat (ENT surgeries in the pediatric population. Effective anesthetic management is vital to ensuring successful ambulatory care and ensuring child and parental satisfaction.Recent findings: This review summarizes recently published studies about the long-term effects of general anesthesia in young children, novel approaches to preoperative fasting and simplified approaches to the assessment and management of emergence delirium (ED and emergence agitation (EA. New developments in perioperative ambulatory care, including management of comorbidities and day care unit logistics, are discussed.Summary: Long-term follow-up of children exposed to general anesthesia before the age of 4 years has limited impact on academic achievement or cognitive performance and should not delay the treatment of common ENT pathology, which can impair speech and language development. A more liberal approach to fasting, employing a 6–4–0 regime allowing children fluids up until theater, may become an accepted practice in future. ED and EA should be discriminated from pain in recovery and, where the child is at risk of harm, should be treated promptly. Postoperative pain at home remains problematic in ambulatory surgery and better parental education is needed. Effective ambulatory care ultimately requires a well-coordinated team approach from effective preassessment to postoperative follow-up. Keywords: myringotomy, ventilation tubes, anesthesia, pediatrics, ambulatory, day case

  15. Improved separation with the intermittently pressed tubing of multilayer coil in type-I counter-current chromatography.

    Science.gov (United States)

    Yang, Yi; Yang, Jiao; Fang, Chen; Wang, Jihui; Gu, Dongyu; Tian, Jing; Ito, Yoichiro

    2018-05-25

    The intermittently pressed tubing was introduced in type-I counter-current chromatographic system as the separation column to improve the separation performance in the present study. The separations were performed with two different solvent systems composed of 1-butanol-acetic acid-water (4:1:5, v/v) (BAW) and hexane-ethyl acetate-methanol-0.1 M HCl (1:1:1:1, v/v) (HEMW) using dipeptides and DNP-amino acids as test samples, respectively. The chromatographic performance was evaluated in terms of retention of the stationary phase (Sf), theoretical plate (N) and peak resolution (Rs). In general, the type-I planetary motion with the multilayer coil of non-modified standard tubing can yield the best separation at a low revolution speed of 200 rpm with lower flow rate. The present results with intermittently pressed tubing indicated that the performance was also optimal at the revolution speed of 200 rpm where the lower flow rate was more beneficial to retention of stationary phase and resolution. In the moderately hydrophobic two-phase solvent system composed of hexane-ethyl acetate-metanol-0.1 M hydrochloric acid (1:1:1:1, v/v), DNP-amino acids were separated with Rs at 1.67 and 1.47, respectively, with 12.66% of stationary phase retention at a flow rate of 0.25 ml/min. In the polar solvent system composed of 1-butanol-acetic acid-water (4:1:5, v/v), dipeptide samples were resolved with Rs at 2.18 and 18.75% of stationary phase retention at a flow rate of 0.25 ml/min. These results indicate that the present system substantially improves the separation efficiency of type-I counter-current chromatographic system. Published by Elsevier B.V.

  16. Method and system for a gas tube-based current source high voltage direct current transmission system

    Science.gov (United States)

    She, Xu; Chokhawala, Rahul Shantilal; Bray, James William; Sommerer, Timothy John; Zhou, Rui; Zhang, Di

    2017-08-29

    A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to "switch on" one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and "switch off" the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.

  17. Effect of the surface film electric resistance on eddy current detectability of surface cracks in Alloy 600 tubes

    International Nuclear Information System (INIS)

    Saario, T.; Paine, J.P.N.

    1995-01-01

    The most widely used technique for NDE of steam generator tubing is eddy current. This technique can reliably detect cracks grown in sodium hydroxide environment only at depths greater than 50% through wall. However, cracking caused by thiosulphate solutions have been detected and sized at shallower depths. The disparity has been proposed to be caused by the different electric resistance of the crack wall surface films and corrosion products in the cracks formed in different environments. This work was undertaken to clarify the role of surface film electric resistance on the disparity found in eddy current detectability of surface cracks in alloy 600 tubes. The proposed model explaining the above mentioned disparity is the following. The detectability of tightly closed cracks by the eddy current technique depends on the electric resistance of the surface films of the crack walls. The nature and resistance of the films which form on the crack walls during operation depends on the composition of the solution inside the crack and close to the crack location. During cooling down of the steam generator, because of contraction and loss of internal pressurization, the cracks are rather tightly closed so that exchange of electrolyte and thus changes in the film properties become difficult. As a result, the surface condition prevailing at high temperature is preserved. If the environment is such that the films formed on the crack walls under operating conditions have low electric resistance, eddy current technique will fail to indicate these cracks or will underestimate the size of these cracks. However, if the electric resistance of the films is high, a tightly closed crack will resemble an open crack and will be easily indicated and correctly sized by eddy current technique

  18. Dual capillary tube / heat exchanger in combination with cycle priming for reducing charge migration

    Science.gov (United States)

    Gomes, Alberto Regio; Kuehl, Steven J.; Litch, Andrew D.; Wu, Guolian

    2017-07-04

    A refrigerator appliance including a multi-capacity compressor and a refrigerant circuit with two conduits and pressure reducing devices arranged in parallel between an evaporator and a condenser. Refrigerant can flow through one, both or none of the conduits and pressure reducing devices. The appliance also has a heat exchanger in contact with either one pressure reducing device, or one conduit between the pressure reducing device and the valve system. The appliance also includes a controller for priming the compressor above a nominal capacity for a predetermined or calculated duration at the beginning of an ON-cycle.

  19. Ambulatory anesthetic care in children undergoing myringotomy and tube placement: current perspectives.

    Science.gov (United States)

    Robinson, Hal; Engelhardt, Thomas

    2017-01-01

    Myringotomy and tube placement is one of the most frequently performed ear, nose and throat (ENT) surgeries in the pediatric population. Effective anesthetic management is vital to ensuring successful ambulatory care and ensuring child and parental satisfaction. This review summarizes recently published studies about the long-term effects of general anesthesia in young children, novel approaches to preoperative fasting and simplified approaches to the assessment and management of emergence delirium (ED) and emergence agitation (EA). New developments in perioperative ambulatory care, including management of comorbidities and day care unit logistics, are discussed. Long-term follow-up of children exposed to general anesthesia before the age of 4 years has limited impact on academic achievement or cognitive performance and should not delay the treatment of common ENT pathology, which can impair speech and language development. A more liberal approach to fasting, employing a 6-4-0 regime allowing children fluids up until theater, may become an accepted practice in future. ED and EA should be discriminated from pain in recovery and, where the child is at risk of harm, should be treated promptly. Postoperative pain at home remains problematic in ambulatory surgery and better parental education is needed. Effective ambulatory care ultimately requires a well-coordinated team approach from effective preassessment to postoperative follow-up.

  20. Contribution to perfecting eddy current testing of steam generator tubes of sodium cooled breeders: description of the Monacault loop for the study of sodium deposit influence

    International Nuclear Information System (INIS)

    Lapicore, A.; Lemarquis, J.C.; Oberlin, C.; Pigeon, M.

    1981-12-01

    In the event of sodium-water reaction in the steam generator of a sodium cooled breeder reactor, it is essential to be able to monitor the local loss of thickness of the tubes located in the reaction area. A method for monitoring the tubes by an eddy current probe is being developed for Super Phenix. The sodium deposits on the outer wall of the tubes, as well as their prolonged contact with high temperature sodium are likely to bring about a change in the signals picked up. A test loop, Monacault, has been built in order to clarify the importance of these parameters (effect of sodium deposits, reproducibility of the wetting at different temperatures). It includes three test cells containing the sample tubes having a total of 61 standard defects to be tested. The first results on the wetting of tubes are given and discussed [fr

  1. Reducing the fuel temperature for pressure-tube supercritical-water-cooled reactors and the effect of fuel burnup

    Energy Technology Data Exchange (ETDEWEB)

    Nichita, E., E-mail: eleodor.nichita@uoit.ca; Kovaltchouk, V., E-mail: vitali.kovaltchouk@uoit.ca

    2015-12-15

    Highlights: • Typical PT-SCWR fuel uses single-region pins consisting of a homogeneous mixture of ThO{sub 2} and PuO{sub 2}. • Using two regions (central for the ThO{sub 2} and peripheral for the PuO{sub 2}) reduces the fuel temperature. • Single-region-pin melting-to-average power ratio is 2.5 at 0.0 MW d/kg and 2.3 at 40 MW d/kg. • Two-region-pin melting-to-average power ratio is 36 at 0.0 MW d/kg and 10.5 at 40 MW d/kg. • Two-region-pin performance drops with burnup due to fissile-element buildup in the ThO{sub 2} region. - Abstract: The Pressure-Tube Supercritical-Water-Cooled Reactor (PT-SCWR) is one of the concepts under investigation by the Generation IV International Forum for its promise to deliver higher thermal efficiency than nuclear reactors currently in operation. The high coolant temperature (>625 K) and high linear power density employed by the PT-SCWR cause the fuel temperature to be fairly high, leading to a reduced margin to fuel melting, thus increasing the risk of actual melting during accident scenarios. It is therefore desirable to come up with a fuel design that lowers the fuel temperature while preserving the high linear power ratio and high coolant temperature. One possible solution is to separate the fertile (ThO{sub 2}) and fissile (PuO{sub 2}) fuel materials into different radial regions in each fuel pin. Previously-reported work found that by locating the fertile material at the centre and the fissile material at the periphery of the fuel pin, the fuel centreline temperature can be reduced by ∼650 K for fresh fuel compared to the case of a homogeneous (Th–Pu)O{sub 2} mixture for the same coolant temperature and linear power density. This work provides a justification for the observed reduction in fuel centreline temperature and suggests a systematic approach to lower the fuel temperature. It also extends the analysis to the dependence of the radial temperature profile on fuel burnup. The radial temperature profile is

  2. Applying computer modeling to eddy current signal analysis for steam generator and heat exchanger tube inspections

    International Nuclear Information System (INIS)

    Sullivan, S.P.; Cecco, V.S.; Carter, J.R.; Spanner, M.; McElvanney, M.; Krause, T.W.; Tkaczyk, R.

    2000-01-01

    Licensing requirements for eddy current inspections for nuclear steam generators and heat exchangers are becoming increasingly stringent. The traditional industry-standard method of comparing inspection signals with flaw signals from simple in-line calibration standards is proving to be inadequate. A more complete understanding of eddy current and magnetic field interactions with flaws and other anomalies is required for the industry to generate consistently reliable inspections. Computer modeling is a valuable tool in improving the reliability of eddy current signal analysis. Results from computer modeling are helping inspectors to properly discriminate between real flaw signals and false calls, and improving reliability in flaw sizing. This presentation will discuss complementary eddy current computer modeling techniques such as the Finite Element Method (FEM), Volume Integral Method (VIM), Layer Approximation and other analytic methods. Each of these methods have advantages and limitations. An extension of the Layer Approximation to model eddy current probe responses to ferromagnetic materials will also be presented. Finally examples will be discussed demonstrating how some significant eddy current signal analysis problems have been resolved using appropriate electromagnetic computer modeling tools

  3. Feasibility study of automatic tube current modulation in low-dose thoracic imaging for young children with 64-slice spiral CT

    International Nuclear Information System (INIS)

    Peng Yun; Li Jianyin; Zhang Qifeng; Liu Yue; Wang Bei; Zheng Jinjin

    2008-01-01

    Objective: To assess the feasibility of using an automatic tube current modulation (ATCM) method to obtain consistent image quality with reduced radiation dose for young children undergoing chest scans with a set of 64-slice spiral CT. Methods: Fifty young children underwent chest scans on a GE 64-slice VCT with automatic tube current modulation. The noise index (NI) for this study group was set to 8 or 9 based on the proposed reference for pediatric chest imaging in our hospital. We compared image quality and radiation dose for the study group with the age-matched control group of 50 young children acquired with standard protocol of fixed-mAs (120 and 150 mAs for under 1 and above 1 year old, respectively). The volume CT dose index(CTDIvol) values were recorded for both groups. Two experienced pediatric radiologists assessed image quality on a 5-point scale with 5 being the best. Scores greater than or equal to 3 were considered clinically acceptable. The degree of interobserver concordance was determined by Kappa statistics. Results: The average objective image noise and CTDIvol for control group was (4.78±0.58) and (6.68±0.62) mGy, respectively. For the study group the mean value of objective mAs was (41.6±11.6) (20-79 mAs) with mean CTDIvol of (2.34±0.71) mGy, and the use of ATCM produced mean noise of (7.84±0.66). The average CTDIvol with the use of NI of 8-9 was about 65% lower than that with the fixed mAs setting. The mean image quality score for the study group and control group was (3.46±0.40) and (4.65±0.46) respectively. All studies had acceptable image quality, and there was good inter-observer agreement in diagnostic acceptability (Kappa=0.474 and 0.536). Conclusion: The automatic tube current modulation method could be used to obtain consistent image quality for young children undergoing 64-slice MSCT chest scans. With proper noise level setting (NI=8 or 9), one may obtain clinically acceptable images with much reduced radiation dose. (authors)

  4. SPIRAL COUNTER-CURRENT CHROMATOGRAPHY OF SMALL MOLECULES, PEPTIDES AND PROTEINS USING THE SPIRAL TUBING SUPPORT ROTOR

    OpenAIRE

    Knight, Martha; Finn, Thomas M.; Zehmer, John; Clayton, Adam; Pilon, Aprile

    2011-01-01

    An important advance in countercurrent chromatography (CCC) carried out in open flow-tubing coils, rotated in planetary centrifuges, is the new design to spread out the tubing in spirals. More spacing between the tubing was found to significantly increase the stationary phase retention, such that now all types of two-phase solvent systems can be used for liquid-liquid partition chromatography in the J-type planetary centrifuges. A spiral tubing support (STS) frame with circular channels was c...

  5. Reduced folate carrier polymorphism (80A-->G) and neural tube defects.

    Science.gov (United States)

    De Marco, Patrizia; Calevo, Maria Grazia; Moroni, Anna; Merello, Elisa; Raso, Alessandro; Finnell, Richard H; Zhu, Huiping; Andreussi, Luciano; Cama, Armando; Capra, Valeria

    2003-03-01

    Transport of folates in mammalian cells occurs by a carrier-mediated mechanism. The human folate carrier (RFC-1) gene has been isolated and characterized. Within this gene, a common polymorphism, 80A-->G, changing a histidine to an arginine in exon 2 (H27R), was recently identified. Defects in folate metabolism, such as defective carrier molecules, could be implicated in the etiology of neural tube defects (NTDs). In the present case-control study, we recruited 174 Italian probands with nonsyndromic NTD, 43 mothers, 53 fathers and 156 control individuals and evaluated the impact of RFC-1 variant on NTD risk. A statistically significant risk was calculated for the 80GG genotype of the NTD cases (OR=2.35; 95% CI 1.21-4.58) and mothers (OR=2.74; 95% CI 0.92-8.38). On the contrary, the heterozygous genotype of the mothers and both heterozygous and homozygous genotypes of the fathers did not seem to be significant NTD risk factors. Furthemore, according to the multifactorial inheritance of NTDs, we demonstrated that the combined genotypes for MTHFR 1298A-->C and RFC-1 80A-->G polymorphisms of cases resulted in greater NTD risk than heterozygosity or homozygosity for RFC-1 80A-->G variant alone. Conversely, our data provide no evidence for an association between NTD phenotype and combined MTHFR C677T/RFC-1 A80G genotypes. Moreover, here we describe the combinations of the two MTHFR polymorphic sites (677CT and 1298AC) with RFC-1 genotypes. We found that both patients and controls could have at most quadruple-mutation combinations. Interestingly, 27% (7/26) of the mothers and 18.75% (30/160) of the cases genotyped presented four mutant alleles in comparison with 8.5% (11/129) of the controls. Finally, the frequency of NTD cases and mothers carrying combined heterozygosity for the two MTHFR polymorphisms and RFC-1 80GG homozygosity (677CT/1298AC/80GG) (cases=11.3%; mothers 11.5%) was increased compared with controls (1.6%). Altogether, our findings support the hypothesis

  6. Attenuation-based size metric for estimating organ dose to patients undergoing tube current modulated CT exams

    Energy Technology Data Exchange (ETDEWEB)

    Bostani, Maryam, E-mail: mbostani@mednet.ucla.edu; McMillan, Kyle; Lu, Peiyun; Kim, Hyun J.; Cagnon, Chris H.; McNitt-Gray, Michael F. [Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90024 (United States); DeMarco, John J. [Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, California 90095 (United States)

    2015-02-15

    Purpose: Task Group 204 introduced effective diameter (ED) as the patient size metric used to correlate size-specific-dose-estimates. However, this size metric fails to account for patient attenuation properties and has been suggested to be replaced by an attenuation-based size metric, water equivalent diameter (D{sub W}). The purpose of this study is to investigate different size metrics, effective diameter, and water equivalent diameter, in combination with regional descriptions of scanner output to establish the most appropriate size metric to be used as a predictor for organ dose in tube current modulated CT exams. Methods: 101 thoracic and 82 abdomen/pelvis scans from clinically indicated CT exams were collected retrospectively from a multidetector row CT (Sensation 64, Siemens Healthcare) with Institutional Review Board approval to generate voxelized patient models. Fully irradiated organs (lung and breasts in thoracic scans and liver, kidneys, and spleen in abdominal scans) were segmented and used as tally regions in Monte Carlo simulations for reporting organ dose. Along with image data, raw projection data were collected to obtain tube current information for simulating tube current modulation scans using Monte Carlo methods. Additionally, previously described patient size metrics [ED, D{sub W}, and approximated water equivalent diameter (D{sub Wa})] were calculated for each patient and reported in three different ways: a single value averaged over the entire scan, a single value averaged over the region of interest, and a single value from a location in the middle of the scan volume. Organ doses were normalized by an appropriate mAs weighted CTDI{sub vol} to reflect regional variation of tube current. Linear regression analysis was used to evaluate the correlations between normalized organ doses and each size metric. Results: For the abdominal organs, the correlations between normalized organ dose and size metric were overall slightly higher for all three

  7. Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kvisgaard, M.; Montgomery, Melanie

    2017-01-01

    Superheater tubes in biomass-fired power plants experience high corrosion rates due to condensation of corrosive alkali chloride-rich deposits. To explore the possibility of reducing the corrosion attack by the formation of an initial protective oxide layer, the corrosion resistance of pre......-oxidised Al and Ti-containing alloys (Kanthal APM and Nimonic 80A, respectively) was investigated under laboratory conditions mimicking biomass firing. The alloys were pre-oxidised at 900°C for 1 week. Afterwards, pre-oxidised samples, and virgin non-pre-oxidised samples as reference, were coated...... with a synthetic deposit of KCl and exposed at 560°C for 1 week to a gas mixture typical of biomass firing. Results show that pre-oxidation could hinder the corrosion attack; however, the relative success was different for the two alloys. While corrosion attack was observed on the pre-oxidised Kanthal APM, the pre...

  8. Numerical Study on the Behaviour of Reduced Beam Section Presence in Rectangular Concrete Filled Tubes Connection

    Science.gov (United States)

    Amalia, A. R.; Suswanto, B.; Kristijanto, H.; Irawan, D.

    2018-01-01

    This paper discusses about the behaviour of two types of RCFT column connections with steel beams due to cyclic loads using software based on finite element method ABAQUS 6.14. This comparison involves modelling RCFT connections with rigid connection that do not allow any deformation and rotation in the joint. There are two types of model to be compared: BB and BRBS which include RCFT connections to ordinary beam without RBS (BB) and to Reduce Beam Section Beam (BRBS). The models behaviour can be discussed in this study are stress value, von misses stress pattern and rotational degree of each model. From the von misses stress pattern value, it found that the highest regions of stress occurs in vicinity of beam flange near column face for connection without RBS (BB). For earthquake resistant building, that behaviour needs to be avoided because sudden collapse often happen in that joint connection. Moreover, the connection with the presence of RBS (BRBS), the highest regions of stress occurs in reduced beam section of the beam, it means that the failure might be happen as proposed plan. The ultimate force that can be restrained by BB model (402 kN) is higher than BRBS model (257,18 kN) because of reducing of flange area. BRBS model has higher rotation angle (0,057 rad) than BB model (0,045 rad). The analysis results also observed that cyclic performances of the moment connection with RBS (BRBS) were more ductile than the connection with ordinary beam (BB).

  9. EddyOne automated analysis of PWR/WWER steam generator tubes eddy current data

    International Nuclear Information System (INIS)

    Nadinic, B.; Vanjak, Z.

    2004-01-01

    INETEC Institute for Nuclear Technology developed software package called Eddy One which has option of automated analysis of bobbin coil eddy current data. During its development and on site use, many valuable lessons were learned which are described in this article. In accordance with previous, the following topics are covered: General requirements for automated analysis of bobbin coil eddy current data; Main approaches to automated analysis; Multi rule algorithms for data screening; Landmark detection algorithms as prerequisite for automated analysis (threshold algorithms and algorithms based on neural network principles); Field experience with Eddy One software; Development directions (use of artificial intelligence with self learning abilities for indication detection and sizing); Automated analysis software qualification; Conclusions. Special emphasis is given on results obtained on different types of steam generators, condensers and heat exchangers. Such results are then compared with results obtained by other automated software vendors giving clear advantage to INETEC approach. It has to be pointed out that INETEC field experience was collected also on WWER steam generators what is for now unique experience.(author)

  10. Electron cyclotron heating/current-drive system using high power tubes for QUEST spherical tokamak

    Science.gov (United States)

    Onchi, Takumi; Idei, H.; Hasegawa, M.; Nagata, T.; Kuroda, K.; Hanada, K.; Kariya, T.; Kubo, S.; Tsujimura, T. I.; Kobayashi, S.; Quest Team

    2017-10-01

    Electron cyclotron heating (ECH) is the primary method to ramp up plasma current non-inductively in QUEST spherical tokamak. A 28 GHz gyrotron is employed for short pulses, where the radio frequency (RF) power is about 300 kW. Current ramp-up efficiency of 0.5 A/W has been obtained with focused beam of the second harmonic X-mode. A quasi-optical polarizer unit has been newly installed to avoid arcing events. For steady-state tokamak operation, 8.56 GHz klystron with power of 200 kW is used as the CW-RF source. The high voltage power supply (54 kV/13 A) for the klystron has been built recently, and initial bench test of the CW-ECH system is starting. The array of insulated-gate bipolar transistor works to quickly cut off the input power for protecting the klystron. This work is supported by JSPS KAKENHI (15H04231), NIFS Collaboration Research program (NIFS13KUTR085, NIFS17KUTR128), and through MEXT funding for young scientists associated with active promotion of national university reforms.

  11. Characterization and implementation of OSL dosimeters for use in evaluating the efficacy of organ-based tube current modulation for CT scans of the face and orbits

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, R. M.; Silosky, M., E-mail: michael.silosky@ucdenver.edu [Department of Radiology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States)

    2015-04-15

    Purpose: The purpose of this work was to characterize commercially available optically stimulated luminescent (OSL) dosimeters for general clinical applications and apply the results to the development of a method to evaluate the efficacy of a vendor-specific organ-based tube current modulation application for both phantom and clinical computed tomography (CT) scans of the face and orbits. Methods: This study consisted of three components: (1) thorough characterization of the dosimeters for CT scans in phantom, including evaluations of depletion, fading, angular dependence, and conversion from counts to absorbed dose; (2) evaluation of the efficacy of using plastic glasses to position the dosimeters over the eyes in both phantom and clinical studies; and (3) preliminary dosimetry measurements made using organ-based tube current modulation in computed tomography dose index (CTDI) and anthropomorphic phantom studies. Results: (1) Depletion effects were found to have a linear relationship with the output of the OSL dosimeters (R{sup 2} = 0.96). Fading was found to affect dosimeter readings during the first two hours following exposure but had no effect during the remaining 60-h period observed. No significant angular dependence was observed for the exposure conditions used in this study (with p-values ranging from 0.9 to 0.26 for all t-tests). Dosimeter counts varied linearly with absorbed dose when measured in the center and 12 o’clock positions of the CTDI phantoms. These linear models of counts versus absorbed dose had overlapping 95% confidence intervals for the intercepts but not for the slopes. (2) When dosimeters were positioned using safety glasses, there was no adverse effect on image quality, and there was no statistically significant difference between this placement and placement of the dosimeters directly on the eyes of the phantom (p = 0.24). (3) When using organ-based tube current modulation, the dose to the lens of the eye was reduced between 19% and

  12. A database for estimating organ dose for coronary angiography and brain perfusion CT scans for arbitrary spectra and angular tube current modulation

    International Nuclear Information System (INIS)

    Rupcich, Franco; Badal, Andreu; Kyprianou, Iacovos; Schmidt, Taly Gilat

    2012-01-01

    Purpose: The purpose of this study was to develop a database for estimating organ dose in a voxelized patient model for coronary angiography and brain perfusion CT acquisitions with any spectra and angular tube current modulation setting. The database enables organ dose estimation for existing and novel acquisition techniques without requiring Monte Carlo simulations. Methods: The study simulated transport of monoenergetic photons between 5 and 150 keV for 1000 projections over 360° through anthropomorphic voxelized female chest and head (0° and 30° tilt) phantoms and standard head and body CTDI dosimetry cylinders. The simulations resulted in tables of normalized dose deposition for several radiosensitive organs quantifying the organ dose per emitted photon for each incident photon energy and projection angle for coronary angiography and brain perfusion acquisitions. The values in a table can be multiplied by an incident spectrum and number of photons at each projection angle and then summed across all energies and angles to estimate total organ dose. Scanner-specific organ dose may be approximated by normalizing the database-estimated organ dose by the database-estimated CTDI vol and multiplying by a physical CTDI vol measurement. Two examples are provided demonstrating how to use the tables to estimate relative organ dose. In the first, the change in breast and lung dose during coronary angiography CT scans is calculated for reduced kVp, angular tube current modulation, and partial angle scanning protocols relative to a reference protocol. In the second example, the change in dose to the eye lens is calculated for a brain perfusion CT acquisition in which the gantry is tilted 30° relative to a nontilted scan. Results: Our database provides tables of normalized dose deposition for several radiosensitive organs irradiated during coronary angiography and brain perfusion CT scans. Validation results indicate total organ doses calculated using our database are

  13. Characterization and implementation of OSL dosimeters for use in evaluating the efficacy of organ-based tube current modulation for CT scans of the face and orbits

    International Nuclear Information System (INIS)

    Marsh, R. M.; Silosky, M.

    2015-01-01

    Purpose: The purpose of this work was to characterize commercially available optically stimulated luminescent (OSL) dosimeters for general clinical applications and apply the results to the development of a method to evaluate the efficacy of a vendor-specific organ-based tube current modulation application for both phantom and clinical computed tomography (CT) scans of the face and orbits. Methods: This study consisted of three components: (1) thorough characterization of the dosimeters for CT scans in phantom, including evaluations of depletion, fading, angular dependence, and conversion from counts to absorbed dose; (2) evaluation of the efficacy of using plastic glasses to position the dosimeters over the eyes in both phantom and clinical studies; and (3) preliminary dosimetry measurements made using organ-based tube current modulation in computed tomography dose index (CTDI) and anthropomorphic phantom studies. Results: (1) Depletion effects were found to have a linear relationship with the output of the OSL dosimeters (R 2 = 0.96). Fading was found to affect dosimeter readings during the first two hours following exposure but had no effect during the remaining 60-h period observed. No significant angular dependence was observed for the exposure conditions used in this study (with p-values ranging from 0.9 to 0.26 for all t-tests). Dosimeter counts varied linearly with absorbed dose when measured in the center and 12 o’clock positions of the CTDI phantoms. These linear models of counts versus absorbed dose had overlapping 95% confidence intervals for the intercepts but not for the slopes. (2) When dosimeters were positioned using safety glasses, there was no adverse effect on image quality, and there was no statistically significant difference between this placement and placement of the dosimeters directly on the eyes of the phantom (p = 0.24). (3) When using organ-based tube current modulation, the dose to the lens of the eye was reduced between 19% and 43

  14. Quantitative Evaluation of Defect in Stainless Steel 304 Tube Using Pulsed Eddy Current Technique

    International Nuclear Information System (INIS)

    Nurul Ain Ahmad Latif; Ilham Mukriz Zainal Abidin; Nurul Ain Ahmad Latif; Nordin Jamaludin; Zaredah Hashim; Norhayati Ramli

    2016-01-01

    Pulsed eddy current (PEC) is an advanced non-destructive testing (NDT) technique that operates based on electromagnetic principle. The excitation consists of broad frequency spectrum leading to be a potential in detecting defects that are deeply buried inside the specimen. In this paper, the experiment and simulation were conducted on stainless steel plate 304 fabricated with open surface defects having a different defect depth as an investigation towards the correlation between extracted signal feature and defect depth. Two common features; time to peak and peak value that corresponds to the location depth of defect and size of defect were used for signals analysis and evaluation. The results that acquired through finite element method (FEM) simulation were compared with experimental results for the signals evaluation and defect quantification. (author)

  15. Counter-current flow in a vertical to horizontal tube with obstructions

    Energy Technology Data Exchange (ETDEWEB)

    Tye, P.; Matuszkiewicz, A.; Teyssedou, A. [Institut de Genie Nucleaire, Quebec (Canada)] [and others

    1995-09-01

    This paper presents experimental results on counter-current flow and flooding in an elbow between a vertical and a horizontal run. The experimental technique used allowed not only the flooding limit to be determined, but also the entire partial delivery region to be studied as well. The influence that various size orifices placed in the horizontal run have on both the delivered liquid flow rates and on the flooding limits is also examined. It is observed that both the flooding limits and the delivered liquid flow rates decrease with decreasing orifice size. Further, it is also observed that the mechanisms that govern the partial delivery of the liquid are significantly different when an orifice is present in the horizontal leg as compared to the case when no orifice is present.

  16. Optimization of Tube Current in Cone-beam Computed Tomography for the Detection of Vertical Root Fractures with Different Intracanal Materials.

    Science.gov (United States)

    Gaêta-Araujo, Hugo; Silva de Souza, Gabriela Queiroz; Freitas, Deborah Queiroz; de Oliveira-Santos, Christiano

    2017-10-01

    There is no consensus about the accuracy of cone-beam computed tomography (CBCT) for detecting vertical root fractures (VRFs), nor is there certainty about the isolated effect of different tube current parameters on the diagnosis of VRF through CBCT scans. This study aimed to evaluate how tube current affects the detection of VRF on CBCT examinations in the absence of intracanal materials and in the presence of gutta-percha (GP) and metal (MP) or fiberglass (FP) intracanal posts. The sample consisted of 320 CBCT scans of tooth roots with and without VRF divided into 8 groups: no fracture/no intracanal material; no fracture + GP; no fracture + MP; no fracture + FP; fracture/no intracanal material; fracture + GP; fracture + MP; fracture + FP. The scans were acquired with an OP300 unit using 4 different milliamperes (4 mA, 8 mA, 10 mA, 13 mA). Five oral radiologists analyzed the images. The area under the receiver operating characteristic curve (Az), sensitivity, specificity, positive and negative predictive values, and interobserver agreement were calculated. Diagnostic performance for the different milliamperes tested was similar for teeth without root filling materials or with FP. Teeth with GP and MP showed the highest Az values for 8 mA and 10 mA, respectively. For teeth with MP, specificity was significantly higher when 10 mA was used. For teeth without root filling materials or with FP, the use of a reduced milliampere does not seem to influence the detection of VRF in a significant manner. For teeth with GP and MP, an increased milliampere may lead to increased diagnostic performance. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Reliable experimental setup to test the pressure modulation of Baerveldt Implant tubes for reducing post-operative hypotony

    Science.gov (United States)

    Ramani, Ajay

    future to evaluate custom inserts and their effects on the pressure drop over 4 -- 6 weeks. The design requirements were: simulate physiological conditions [flow rate between 1.25 and 2.5 mul/min], evaluate small inner diameter tubes [50 and 75 mum] and annuli, and demonstrate reliability and repeatability. The current study was focused on benchmarking the experimental setup for the IOP range of 15 -- 20 mm Hg. Repeated experiments have been conducted using distilled water with configurations [diameter of tube, insert diameter, lengths of insert and tube, and flow rate] that produce pressure variations which include the 15 -- 20 mm Hg range. Two similar setups were assembled and evaluated for repeatability between the two. Experimental measurements of pressure drop were validated using theoretical calculations. Theory predicted a range of expected values by considering manufacturing and performance tolerances of the apparatus components: tube diameter, insert diameter, and the flow-rate and pressure [controlled by pump]. In addition, preliminary experiments evaluated the dissolution of suture samples in a balanced salt solution and in distilled water. The balanced salt solution approximates the eye's aqueous humor properties, and it was expected that the salt and acid would help to hydrolyze sutures much faster than distilled water. Suture samples in a balanced salt solution showed signs of deterioration [flaking] within 23 days, and distilled water samples showed only slight signs of deterioration after about 30 days. These preliminary studies indicate that future dissolution and flow experiments should be conducted using the balanced salt solution. Also, the absorbable sutures showed signs of bulk erosion/deterioration in a balanced salt solution after 14 days, which indicates that they may not be suitable as inserts in the implant tubes because flakes could block the tube entrance. Further long term studies should be performed in order to understand the effects of

  18. Angular on-line tube current modulation in multidetector CT examinations of children and adults: The influence of different scanning parameters on dose reduction

    International Nuclear Information System (INIS)

    Papadakis, Antonios E.; Perisinakis, Kostas; Damilakis, John

    2007-01-01

    The purpose of this study was to assess the potential of angular on-line tube current modulation on dose reduction in pediatric and adult patients undergoing multidetector computed tomography (MDCT) examinations. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-year-old, 5-year-old, 10-year-old, and adult were employed in the current study. Phantoms were scanned with the use of on-line tube current modulation (TCM). Percent dose reduction (%DR) factors achieved by applying TCM, were determined for standard protocols used for head and neck, shoulder, thorax, thorax and abdomen, abdomen, abdomen and pelvis, pelvis, and whole body examinations. A preliminary study on the application of TCM in MDCT examinations of adult patients was performed to validate the results obtained in anthropomorphic phantoms. Dose reduction was estimated as the percentage difference of the modulated milliamperes for each scan and the preset milliamperes prescribed by the scan protocol. The dose reduction in children was found to be much lower than the corresponding reduction achieved for adults. For helical scans the %DR factors, ranged between 1.6% and 7.4% for the neonate, 2.9% and 8.7% for the 1-year old, 2% and 6% for the 5-year-old, 5% and 10.9% for the 10-year-old, and 10.4% and 20.7% for the adult individual. For sequential scans the corresponding %DR factors ranged between 1.3% and 6.7%, 4.5% and 11%, 4.2% and 6.6%, 6.4% and 12.3%, and 8.9% and 23.3%, respectively. Broader beam collimations are associated with decreased %DR factors, when other scanning parameters are held constant. TCM did not impair image noise. In adult patients, the %DR values were found to be in good agreement with the corresponding results obtained in the anthropomorphic adult phantom. In conclusion, on-line TCM may be considered as a valuable tool for reducing dose in routine CT examinations of pediatric and adult patients. However, the dose reduction achieved with TCM

  19. Current status of materials development of nuclear fuel cladding tubes for light water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Zhengang, E-mail: duan_zg@imr.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Yang, Huilong [Department of Nuclear Engineering, School of Engineering, The University of Tokyo, Nakagun, Ibaraki 319-1188 (Japan); Satoh, Yuhki [Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Murakami, Kenta; Kano, Sho; Zhao, Zishou; Shen, Jingjie [Department of Nuclear Engineering, School of Engineering, The University of Tokyo, Nakagun, Ibaraki 319-1188 (Japan); Abe, Hiroaki, E-mail: abe.hiroaki@n.t.u-tokyo.ac.jp [Department of Nuclear Engineering, School of Engineering, The University of Tokyo, Nakagun, Ibaraki 319-1188 (Japan)

    2017-05-15

    Zirconium-based (Zr-based) alloys have been widely used as materials for the key components in light water reactors (LWRs), such as fuel claddings which suffer from waterside corrosion, hydrogen uptakes and strength loss at elevated temperature, especially during accident scenarios like the lost-of-coolant accident (LOCA). For the purpose of providing a safer, nuclear leakage resistant and economically viable LWRs, three general approaches have been proposed so far to develop the accident tolerant fuel (ATF) claddings: optimization of metallurgical composition and processing of Zr-based alloys, coatings on existing Zr-based alloys and replacement of current Zr-based alloys. In this manuscript, an attempt has been made to systematically present the historic development of Zr-based cladding, including the impacts of alloying elements on the material properties. Subsequently, the research investigations on coating layer on the surface of Zr-based claddings, mainly referring coating materials and fabrication methods, have been broadly reviewed. The last section of this review provides the introduction to alternative materials (Non-Zr) to Zr-based alloys for LWRs, such as advanced steels, Mo-based, and SiC-based materials.

  20. Current status of materials development of nuclear fuel cladding tubes for light water reactors

    International Nuclear Information System (INIS)

    Duan, Zhengang; Yang, Huilong; Satoh, Yuhki; Murakami, Kenta; Kano, Sho; Zhao, Zishou; Shen, Jingjie; Abe, Hiroaki

    2017-01-01

    Zirconium-based (Zr-based) alloys have been widely used as materials for the key components in light water reactors (LWRs), such as fuel claddings which suffer from waterside corrosion, hydrogen uptakes and strength loss at elevated temperature, especially during accident scenarios like the lost-of-coolant accident (LOCA). For the purpose of providing a safer, nuclear leakage resistant and economically viable LWRs, three general approaches have been proposed so far to develop the accident tolerant fuel (ATF) claddings: optimization of metallurgical composition and processing of Zr-based alloys, coatings on existing Zr-based alloys and replacement of current Zr-based alloys. In this manuscript, an attempt has been made to systematically present the historic development of Zr-based cladding, including the impacts of alloying elements on the material properties. Subsequently, the research investigations on coating layer on the surface of Zr-based claddings, mainly referring coating materials and fabrication methods, have been broadly reviewed. The last section of this review provides the introduction to alternative materials (Non-Zr) to Zr-based alloys for LWRs, such as advanced steels, Mo-based, and SiC-based materials.

  1. Fabrication of Bi2223 bulks with high critical current properties sintered in Ag tubes

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Yasuaki, E-mail: ytakeda@g.ecc.u-tokyo.ac.jp [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shimoyama, Jun-ichi; Motoki, Takanori [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258 (Japan); Kishio, Kohji [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nakashima, Takayoshi; Kagiyama, Tomohiro; Kobayashi, Shin-ichi; Hayashi, Kazuhiko [Sumitomo Electric Industries, Ltd. 1-1-3 Shimaya, Konohana-ku, Osaka 554-0024 (Japan)

    2017-03-15

    Highlights: • Fabrication conditions of Bi2223 bulks was reconsidered in terms of high J{sub c}. • Pressure of uniaxial pressing and heat treatment conditions were investigated. • The best sample showed higher J{sub c} than that of practically used Bi2223 bulks. - Abstract: Randomly grain oriented Bi2223 sintered bulks are one of the representative superconducting materials having weak-link problem due to very short coherence length particularly along the c-axis, resulting in poor intergrain J{sub c} properties. In our previous studies, sintering and/or post-annealing under moderately reducing atmospheres were found to be effective for improving grain coupling in Bi2223 sintered bulks. Further optimizations of the synthesis process for Bi2223 sintered bulks were attempted in the present study to enhance their intergrain J{sub c}. Effects of applied pressure of uniaxial pressing and sintering conditions on microstructure and superconducting properties have been systematically investigated. The best sample showed intergrain J{sub c} of 2.0 kA cm{sup −2} at 77 K and 8.2 kA cm{sup −2} at 20 K, while its relative density was low ∼65%. These values are quite high as for a randomly oriented sintered bulk of cuprate superconductors.

  2. Eddy currents inspection of CANDU steam generator' tubes using Zetec's ZR-1 Robot: experience in Romania

    Energy Technology Data Exchange (ETDEWEB)

    Hower, S. [Zetec Inc., Quebec, Quebec (Canada); Serban, M. [CNE-Prod U1 Cernavoda (Romania); Vladu, L. [Compcontrol Ing., Bucharest (Romania)

    2006-07-01

    'Full text:' The paper introduces the new ZR-1 Robot System for Inspection and Maintenance/Repair from Zetec that combines the newest state-of-the-art robotics technology with Zetec experience-based innovation to address the needs for inspection and repair of steam generators. The multipurpose ZR-1 can be easily installed to perform the necessary eddy current inspection and remain installed ready for follow-up maintenance and repair. It has superior technical performances and a modular three axis motion of arm that enables 100% coverage of tube sheet. Automated, repeatable, and precise positioning of toolheads, ensures accurate delivery and reducing costly rework and reduces inspection time by 30%. The modular, lightweight, and portable design permits easy assembly and disassembly through small openings and it reduces setup/tear down time by 30%. The first deployment of the new ZR-1 Robot was made in September 2004 at the Cernavoda NPP inspection outage. The Cernavoda plant has four Advanced 600 MW CANDU-design generators that have been in service since 1996. The paper presents also the Zetec's filed experience and customer experience with this system. It describes the equipment setup in Cernavoda's generator mock-up, functional testes and calibration. Finally, provides details on the execution of the inspection, options for standardizing the inspection techniques and conclusions. (author)

  3. Helical CT for lung-cancer screening. 3. Fundamental study for ultra-low-dose CT by application of small tube current and filter

    International Nuclear Information System (INIS)

    Itoh, Shigeki; Koyama, Shuji; Tusaka, Masatoshi; Maekoshi, Hisashi; Satake, Hiroko; Ishigaki, Takeo.

    1996-01-01

    In order to develop ultra-low-dose helical CT for lung cancer screening, the effect of reduction of the tube current to 20 mA and application of a 10 mm thick aluminium filter upon radiation dose and image quality was evaluated with a phantom. Exposure dose at the center of a gantry and absorbed dose at the center of an acrylic phantom at 20 mA with the filter were 15% and 29% of the dose at 50 mA without the filter, respectively. For reduction of absorbed dose, reduction of the tube current was more useful than application of the filter. Image noise at 20 mA with the filter was double that at 50 mA without the filter. Neither reduction of the tube current nor application of the filter changed full width at half maximum on section sensitivity of the Z-axis. Although reduction of the tube current did not affect the difference in CT values between an acrylic sphere and styroform, application of the filter caused a reduction of 4.5% in the difference in CT values. Neither reduction of the tube current nor application of the filter affected the contrast resolution of the high-contrast phantom; however, that of the low-contrast phantom deteriorated. Although improvement of the filter and evaluation of clinical images are necessary, reduction of the tube current to 20 mA and application of the aluminium filter appear to be a promising method for ultra-low-dose helical CT of the lung. (author)

  4. Comparison of Measured and Estimated CT Organ Doses for Modulated and Fixed Tube Current:: A Human Cadaver Study.

    Science.gov (United States)

    Padole, Atul; Deedar Ali Khawaja, Ranish; Otrakji, Alexi; Zhang, Da; Liu, Bob; Xu, X George; Kalra, Mannudeep K

    2016-05-01

    The aim of this study was to compare the directly measured and the estimated computed tomography (CT) organ doses obtained from commercial radiation dose-tracking (RDT) software for CT performed with modulated tube current or automatic exposure control (AEC) technique and fixed tube current (mAs). With the institutional review board (IRB) approval, the ionization chambers were surgically implanted in a human cadaver (88 years old, male, 68 kg) in six locations such as liver, stomach, colon, left kidney, small intestine, and urinary bladder. The cadaver was scanned with routine abdomen pelvis protocol on a 128-slice, dual-source multidetector computed tomography (MDCT) scanner using both AEC and fixed mAs. The effective and quality reference mAs of 100, 200, and 300 were used for AEC and fixed mAs, respectively. Scanning was repeated three times for each setting, and measured and estimated organ doses (from RDT software) were recorded (N = 3*3*2 = 18). Mean CTDIvol for AEC and fixed mAs were 4, 8, 13 mGy and 7, 14, 21 mGy, respectively. The most estimated organ doses were significantly greater (P < 0.01) than the measured organ doses for both AEC and fixed mAs. At AEC, the mean estimated organ doses (for six organs) were 14.7 mGy compared to mean measured organ doses of 12.3 mGy. Similarly, at fixed mAs, the mean estimated organ doses (for six organs) were 24 mGy compared to measured organ doses of 22.3 mGy. The differences among the measured and estimated organ doses were higher for AEC technique compared to the fixed mAs for most organs (P < 0.01). The most CT organ doses estimated from RDT software are greater compared to directly measured organ doses, particularly when AEC technique is used for CT scanning. Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  5. New Czechoslovak detector of leaking condenser tubes usable in both shutdown and reduced output operation of power unit

    International Nuclear Information System (INIS)

    Matal, O.; Klinga, J.; Varvarovsky, F.; Zachar, J.; Fratric, D.

    1986-01-01

    The main reason for penetration of undesirable admixtures from cooling water in the condensate is the inleakage of steam turbine condensers. Briefly assessed are the means and methods of detecting and locating condenser leaks used in the world and in power facilities in Czechoslovakia. Equipment was developed based on measuring the difference between the pressure in a temporarily closed condenser tube and ambient pressure, for leak testing of condenser tubes during operation and during shutdown of WWER-440 units. Two types of the equipment were tested in practice. Type VUEZ-PHN 85P meets the requirements of objective leak tests and those of leak location in condenser tubes and of leak detection in tube expansion in the tube plates of WWER-440 unit condensers, this as concerns sensitivity, the objectivity of results, the cost of tests, and minimal losses of power during the test. Type VUEZ-PHN 85P can be used for leak location in all tube type heat exchangers with access to tube outlets in which under- or overpressure can be achieved in the space between the tubes relative to ambient pressure during the test. (Z.M.) 5 figs., 4 tabs., 11 refs

  6. Comparison of characteristics parameters in the evaluation of wall thickness diminishing in admiralty brass tubes of the steam condenser, tested by eddy currents

    International Nuclear Information System (INIS)

    Obrutsky, Alba E.; Mendez, Jorge A.; Acosta, Cesar D.; Scopelliti, Jose D.

    1999-01-01

    This work is aimed to appraise the measure of the wall thickness diminishing in the signals evaluation obtained in the inspection of steam condenser by eddy currents. In the analysis of the obtained signals were observed in the brass tubes a great quantity of internal defects whose signal indicates that there were diminishing of the wall thickness between 80% and 100%. With all this information and analyzing the data acquired, the tubes with more important indications were selected to make a more exhaustive study of the found defectology. As first test, it was measured the thickness of the worn tubes, comparing them with the original ones that are in stock. It was verified that the tubes separated for this study presented a 30% less thickness in comparison with the new tubes. A semiquantitative chemical test (EDAX) was made to verify if it was the same material. One of the extracted tubes (066 Y1) was reinspected in order to isolate the area with indications. Once this was performed, it was decided to cut the tube to make a visual inspection and to evaluate to what type of defect corresponds to the signals obtained. In the metallography it was confirm that it was a horseshoe type defect. When performing a dimensional control test of the found real defect, it was checked that the information obtained by eddy currents regarding the diminishing of the wall thickness diminishing was valid. At a last stage of the test, it was proceed to make an study and verification of the used parameters, probes, standards and finally determine which shall be the convenient modifications to minimize errors. (author)

  7. Effective dose and organ doses estimation taking tube current modulation into account with a commercial software package

    International Nuclear Information System (INIS)

    Lopez-Rendon, X.; Bosmans, H.; Zanca, F.; Oyen, R.

    2015-01-01

    To evaluate the effect of including tube current modulation (TCM) versus using the average mAs in estimating organ and effective dose (E) using commercial software. Forty adult patients (24 females, 16 males) with normal BMI underwent chest/abdomen computed tomography (CT) performed with TCM at 120 kVp, reference mAs of 110 (chest) and 200 (abdomen). Doses to fully irradiated organs (breasts, lungs, stomach, liver and ovaries) and E were calculated using two versions of a dosimetry software: v.2.0, which uses the average mAs, and v.2.2, which accounts for TCM by implementing a gender-specific mAs profile. Student's t-test was used to assess statistically significant differences between organ doses calculated with the two versions. A statistically significant difference (p < 0.001) was found for E on chest and abdomen CT, with E being lower by 4.2 % when TCM is considered. Similarly, organ doses were also significantly lower (p < 0.001): 13.7 % for breasts, 7.3 % for lungs, 9.1 % for the liver and 8.5 % for the stomach. Only the dose to the ovaries was higher with TCM (11.5 %). When TCM is used, for the stylized phantom, the doses to lungs, breasts, stomach and liver decreased while the dose to the ovaries increased. (orig.)

  8. Evaluation of critical current density and residual resistance ratio limits in powder in tube Nb$_{3}$Sn conductors

    CERN Document Server

    Segal, Christopher; Sung, Zu Hawn; Lee, Peter J; Sailer, Bernd; Thoener, Manfred; Schlenga, Klaud; Ballarino, Amalia; Bottura, Luca; Bordini, Bernardo; Scheuerlein, Christian; Larnalestier, David C

    2016-01-01

    High critical current density ( Jc) Nb$_{3}$Sn A15 multifilamentary wires require a large volume fraction of small grain (SG), superconducting A15 phase, as well as Cu stabilizer with high Residual Resistance Ratio (RRR) to provide electromagnetic stabilization and protection. In powder-in-tube (PIT) wires the unreacted Nb7.5 wt%Ta outer layer of the tubular filaments acts as a diffusion barrier and protects the interfilamentary Cu stabilizer from Sn contamination. A high RRR requirement generally imposes a restricted A15 reaction heat treatment to prevent localized full reaction of the filament that could allow Sn to reach the Cu. In this study we investigate recent high quality PIT wires that achieve a Jc (12 T, 4.2 K) up to ∼2500 A mm−2 and find that the minimum diffusion barrier thickness decreases as the filament aspect ratio increases from ∼1 in the inner rings of filaments to 1.3 in the outer filament rings. We found that just 2–3 diffusion barrier breaches can degrade RRR from 300 to 150 or le...

  9. Techniques for processing remote field eddy current signals from bend regions of steam generator tubes of prototype fast breeder reactor

    Energy Technology Data Exchange (ETDEWEB)

    Thirunavukkarasu, S. [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India); Rao, B.P.C., E-mail: bpcrao@igcar.gov.in [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India); Jayakumar, T.; Raj, Baldev [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India)

    2011-04-15

    Steam generator (SG) is one of the most critical components of sodium cooled fast breeder reactor. Remote field eddy current (RFEC) technique has been chosen for in-service inspection (ISI) of these ferromagnetic SG tubes made of modified 9Cr-1Mo steel (Grade 91). Expansion bends are provided in the SGs to accommodate differential thermal expansion. During ISI using RFEC technique, in expansion bend regions, exciter-receiver coil misalignment, bending stresses, probe wobble and magnetic permeability variations produce disturbing noise hindering detection of defects. Fourier filtering, cross-correlation and wavelet transform techniques have been studied for noise reduction as well as enhancement of RFEC signals of defects in bend regions, having machined grooves and localized defects. Performance of these three techniques has been compared using signal-to-noise ratio (SNR). Fourier filtering technique has shown better performance for noise reduction while cross-correlation technique has resulted in significant enhancement of signals. Wavelet transform technique has shown the combined capability of noise reduction and signal enhancement and resulted in unambiguous detection of 10% of wall loss grooves and localized defects in the bend regions with SNR better than 7 dB.

  10. Effective dose and organ doses estimation taking tube current modulation into account with a commercial software package

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Rendon, X. [KU Leuven, Department of Imaging and Pathology, Division of Medical Physics and Quality Assessment, Herestraat 49, box 7003, Leuven (Belgium); Bosmans, H.; Zanca, F. [KU Leuven, Department of Imaging and Pathology, Division of Medical Physics and Quality Assessment, Herestraat 49, box 7003, Leuven (Belgium); University Hospitals Leuven, Department of Radiology, Leuven (Belgium); Oyen, R. [University Hospitals Leuven, Department of Radiology, Leuven (Belgium)

    2015-07-15

    To evaluate the effect of including tube current modulation (TCM) versus using the average mAs in estimating organ and effective dose (E) using commercial software. Forty adult patients (24 females, 16 males) with normal BMI underwent chest/abdomen computed tomography (CT) performed with TCM at 120 kVp, reference mAs of 110 (chest) and 200 (abdomen). Doses to fully irradiated organs (breasts, lungs, stomach, liver and ovaries) and E were calculated using two versions of a dosimetry software: v.2.0, which uses the average mAs, and v.2.2, which accounts for TCM by implementing a gender-specific mAs profile. Student's t-test was used to assess statistically significant differences between organ doses calculated with the two versions. A statistically significant difference (p < 0.001) was found for E on chest and abdomen CT, with E being lower by 4.2 % when TCM is considered. Similarly, organ doses were also significantly lower (p < 0.001): 13.7 % for breasts, 7.3 % for lungs, 9.1 % for the liver and 8.5 % for the stomach. Only the dose to the ovaries was higher with TCM (11.5 %). When TCM is used, for the stylized phantom, the doses to lungs, breasts, stomach and liver decreased while the dose to the ovaries increased. (orig.)

  11. Do we need 3D tube current modulation information for accurate organ dosimetry in chest CT? Protocols dose comparisons

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Rendon, Xochitl; Develter, Wim [KU Leuven, Department of Imaging and Pathology, Division of Medical Physics and Quality Assessment, Leuven (Belgium); Zhang, Guozhi; Coudyzer, Walter; Zanca, Federica [University Hospitals of the KU Leuven, Department of Radiology, Leuven (Belgium); Bosmans, Hilde [KU Leuven, Department of Imaging and Pathology, Division of Medical Physics and Quality Assessment, Leuven (Belgium); University Hospitals of the KU Leuven, Department of Radiology, Leuven (Belgium)

    2017-11-15

    To compare the lung and breast dose associated with three chest protocols: standard, organ-based tube current modulation (OBTCM) and fast-speed scanning; and to estimate the error associated with organ dose when modelling the longitudinal (z-) TCM versus the 3D-TCM in Monte Carlo simulations (MC) for these three protocols. Five adult and three paediatric cadavers with different BMI were scanned. The CTDI{sub vol} of the OBTCM and the fast-speed protocols were matched to the patient-specific CTDI{sub vol} of the standard protocol. Lung and breast doses were estimated using MC with both z- and 3D-TCM simulated and compared between protocols. The fast-speed scanning protocol delivered the highest doses. A slight reduction for breast dose (up to 5.1%) was observed for two of the three female cadavers with the OBTCM in comparison to the standard. For both adult and paediatric, the implementation of the z-TCM data only for organ dose estimation resulted in 10.0% accuracy for the standard and fast-speed protocols, while relative dose differences were up to 15.3% for the OBTCM protocol. At identical CTDI{sub vol} values, the standard protocol delivered the lowest overall doses. Only for the OBTCM protocol is the 3D-TCM needed if an accurate (<10.0%) organ dosimetry is desired. (orig.)

  12. Hypoglossal-Facial Nerve Reconstruction Using a Y-Tube-Conduit Reduces Aberrant Synkinetic Movements of the Orbicularis Oculi and Vibrissal Muscles in Rats

    Directory of Open Access Journals (Sweden)

    Yasemin Kaya

    2014-01-01

    Full Text Available The facial nerve is the most frequently damaged nerve in head and neck trauma. Patients undergoing facial nerve reconstruction often complain about disturbing abnormal synkinetic movements of the facial muscles (mass movements, synkinesis which are thought to result from misguided collateral branching of regenerating motor axons and reinnervation of inappropriate muscles. Here, we examined whether use of an aorta Y-tube conduit during reconstructive surgery after facial nerve injury reduces synkinesis of orbicularis oris (blink reflex and vibrissal (whisking musculature. The abdominal aorta plus its bifurcation was harvested (N = 12 for Y-tube conduits. Animal groups comprised intact animals (Group 1, those receiving hypoglossal-facial nerve end-to-end coaptation alone (HFA; Group 2, and those receiving hypoglossal-facial nerve reconstruction using a Y-tube (HFA-Y-tube, Group 3. Videotape motion analysis at 4 months showed that HFA-Y-tube group showed a reduced synkinesis of eyelid and whisker movements compared to HFA alone.

  13. A simple tool for tubing modification to improve spiral high-speed counter-current chromatography for protein purification.

    Science.gov (United States)

    Ito, Yoichiro; Ma, Xiaofeng; Clary, Robert

    2016-01-01

    A simple tool is introduced which can modify the shape of tubing to enhance the partition efficiency in high-speed countercurrent chromatography. It consists of a pair of interlocking identical gears, each coaxially holding a pressing wheel to intermittently compress plastic tubing in 0 - 10 mm length at every 1 cm interval. The performance of the processed tubing is examined in protein separation with 1.6 mm ID PTFE tubing intermittently pressed in 3 mm and 10 mm width both at 10 mm intervals at various flow rates and revolution speeds. A series of experiments was performed with a polymer phase system composed of polyethylene glycol and dibasic potassium phosphate each at 12.5% (w/w) in deionized water using three protein samples. Overall results clearly demonstrate that the compressed tubing can yield substantially higher peak resolution than the non-processed tubing. The simple tubing modifier is very useful for separation of proteins with high-speed countercurrent chromatography.

  14. Gastroenteric tube feeding: Techniques, problems and solutions

    Science.gov (United States)

    Blumenstein, Irina; Shastri, Yogesh M; Stein, Jürgen

    2014-01-01

    Gastroenteric tube feeding plays a major role in the management of patients with poor voluntary intake, chronic neurological or mechanical dysphagia or gut dysfunction, and patients who are critically ill. However, despite the benefits and widespread use of enteral tube feeding, some patients experience complications. This review aims to discuss and compare current knowledge regarding the clinical application of enteral tube feeding, together with associated complications and special aspects. We conducted an extensive literature search on PubMed, Embase and Medline using index terms relating to enteral access, enteral feeding/nutrition, tube feeding, percutaneous endoscopic gastrostomy/jejunostomy, endoscopic nasoenteric tube, nasogastric tube, and refeeding syndrome. The literature showed common routes of enteral access to include nasoenteral tube, gastrostomy and jejunostomy, while complications fall into four major categories: mechanical, e.g., tube blockage or removal; gastrointestinal, e.g., diarrhea; infectious e.g., aspiration pneumonia, tube site infection; and metabolic, e.g., refeeding syndrome, hyperglycemia. Although the type and frequency of complications arising from tube feeding vary considerably according to the chosen access route, gastrointestinal complications are without doubt the most common. Complications associated with enteral tube feeding can be reduced by careful observance of guidelines, including those related to food composition, administration rate, portion size, food temperature and patient supervision. PMID:25024606

  15. Method for shaping polyethylene tubing

    Science.gov (United States)

    Kramer, R. C.

    1981-01-01

    Method forms polyethylene plastic tubing into configurations previously only possible with metal tubing. By using polyethylene in place of copper or stain less steel tubing inlow pressure systems, fabrication costs are significantly reduced. Polyethylene tubing can be used whenever low pressure tubing is needed in oil operations, aircraft and space applications, powerplants, and testing laboratories.

  16. Chest tube drainage of pleural effusions--an audit of current practice and complications at Hutt Hospital.

    Science.gov (United States)

    Epstein, Erica; Jayathissa, Sisira; Dee, Stephen

    2012-05-11

    The aims of the study were to review small-bore chest tube insertion practices for drainage of pleural fluid at Hutt Valley District Health Board (HVDHB), to assess complications, and compare the findings with international data. Retrospective analysis of clinical records was completed on all chest tube insertions for drainage of pleural fluid at HVDHB from December 2008 to November 2009. Descriptive statistics were used to present demographics and tube-associated complications. Comparison was made to available similar international data. Small-bore tubes comprised 59/65 (91%) chest tube insertions and 23/25 (92%) complications. Available comparative data was limited. Ultrasound was used in 36% of insertions. Nearly half of chest drains placed for empyema required subsequent cardiothoracic surgical intervention. Chest drain complication rates at HVDHB were comparable to those seen internationally. Referral rates to cardiothoracic surgery for empyema were within described ranges. The importance of procedural training for junior medical staff, optimising safety of drain insertions with ultrasound guidance, and clear clinical governance for chest tube insertions are important in minimising harm from this procedure. Specialist societies need to take a leadership in providing guidance on chest drain insertions to secondary and tertiary hospitals in Australia and New Zealand.

  17. CT vs 68Ge attenuation correction in a combined PET/CT system: evaluation of the effect of lowering the CT tube current

    International Nuclear Information System (INIS)

    Kamel, Ehab; Hany, Thomas F.; Burger, Cyrill; Treyer, Valerie; Schulthess von, Gustav K.; Buck, Alfred; Lonn, Albert H.R.

    2002-01-01

    With the introduction of combined positron emission tomography/computed tomography (PET/CT) systems, several questions have to be answered. In this work we addressed two of these questions: (a) to what value can the CT tube current be reduced while still yielding adequate maps for the attenuation correction of PET emission scans and (b) how do quantified uptake values in tumours derived from CT and germanium-68 attenuation correction compare. In 26 tumour patients, multidetector CT scans were acquired with 10, 40, 80 and 120 mA (CT 10 , CT 40 , CT 80 and CT 120 ) and used for the attenuation correction of a single FDG PET emission scan, yielding four PET scans designated PET CT10 -PET CT120 . In 60 tumorous lesions, FDG uptake and lesion size were quantified on PET CT10 -PET CT120 . In another group of 18 patients, one CT scan acquired with 80 mA and a standard transmission scan acquired using 68 Ge sources were employed for the attenuation correction of the FDG emission scan (PET CT80 , PET 68Ge ). Uptake values and lesion size in 26 lesions were compared on PET CT80 and PET 68Ge . In the first group of patients, analysis of variance revealed no significant effect of CT current on tumour FDG uptake or lesion size. In the second group, tumour FDG uptake was slightly higher using CT compared with 68 Ge attenuation correction, especially in lesions with high FDG uptake. Lesion size was similar on PET CT80 and PET 68Ge . In conclusion, low CT currents yield adequate maps for the attenuation correction of PET emission scans. Although the discrepancy between CT- and 68 Ge-derived uptake values is probably not relevant in most cases, it should be kept in mind if standardised uptake values derived from CT and 68 Ge attenuation correction are compared. (orig.)

  18. Do we need 3D tube current modulation information for accurate organ dosimetry in chest CT? Protocols dose comparisons.

    Science.gov (United States)

    Lopez-Rendon, Xochitl; Zhang, Guozhi; Coudyzer, Walter; Develter, Wim; Bosmans, Hilde; Zanca, Federica

    2017-11-01

    To compare the lung and breast dose associated with three chest protocols: standard, organ-based tube current modulation (OBTCM) and fast-speed scanning; and to estimate the error associated with organ dose when modelling the longitudinal (z-) TCM versus the 3D-TCM in Monte Carlo simulations (MC) for these three protocols. Five adult and three paediatric cadavers with different BMI were scanned. The CTDI vol of the OBTCM and the fast-speed protocols were matched to the patient-specific CTDI vol of the standard protocol. Lung and breast doses were estimated using MC with both z- and 3D-TCM simulated and compared between protocols. The fast-speed scanning protocol delivered the highest doses. A slight reduction for breast dose (up to 5.1%) was observed for two of the three female cadavers with the OBTCM in comparison to the standard. For both adult and paediatric, the implementation of the z-TCM data only for organ dose estimation resulted in 10.0% accuracy for the standard and fast-speed protocols, while relative dose differences were up to 15.3% for the OBTCM protocol. At identical CTDI vol values, the standard protocol delivered the lowest overall doses. Only for the OBTCM protocol is the 3D-TCM needed if an accurate (<10.0%) organ dosimetry is desired. • The z-TCM information is sufficient for accurate dosimetry for standard protocols. • The z-TCM information is sufficient for accurate dosimetry for fast-speed scanning protocols. • For organ-based TCM schemes, the 3D-TCM information is necessary for accurate dosimetry. • At identical CTDI vol , the fast-speed scanning protocol delivered the highest doses. • Lung dose was higher in XCare than standard protocol at identical CTDI vol .

  19. Spiral counter-current chromatography of small molecules, peptides and proteins using the spiral tubing support rotor.

    Science.gov (United States)

    Knight, Martha; Finn, Thomas M; Zehmer, John; Clayton, Adam; Pilon, Aprile

    2011-09-09

    An important advance in countercurrent chromatography (CCC) carried out in open flow-tubing coils, rotated in planetary centrifuges, is the new design to spread out the tubing in spirals. More spacing between the tubing was found to significantly increase the stationary phase retention, such that now all types of two-phase solvent systems can be used for liquid-liquid partition chromatography in the J-type planetary centrifuges. A spiral tubing support (STS) frame with circular channels was constructed by laser sintering technology into which FEP tubing was placed in 4 spiral loops per layer from the bottom to the top and a cover affixed allowing the tubing to connect to flow-tubing of the planetary centrifuge. The rotor was mounted and run in a P.C. Inc. type instrument. Examples of compounds of molecular weights ranging from <300 to approximately 15,000 were chromatographed in appropriate two-phase solvent systems to assess the capability for separation and purification. A mixture of small molecules including aspirin was completely separated in hexane-ethyl acetate-methanol-water. Synthetic peptides including a very hydrophobic peptide were each purified to a very high purity level in a sec-butanol solvent system. In the STS rotor high stationary phase retention was possible with the aqueous sec-butanol solvent system at a normal flow rate. Finally, the two-phase aqueous polyethylene glycol-potassium phosphate solvent system was applied to separate a protein from a lysate of an Escherichia coli expression system. These experiments demonstrate the versatility of spiral CCC using the STS rotor. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. The second eddy current testing of zircaloy tube samples from the OECD Halden reactor project at Reactor Fuel Examination Facility, Tokai, JAERI

    International Nuclear Information System (INIS)

    Ohwada, Isao; Nishino, Yasuharu

    1986-07-01

    The Reactor Fuel Examination Facility in Tokai/JAERI (Japan Atomic Energy Research Institute) joined to the second round robin programme on eddy current test of the Halden/IFE. In the programme, two zircaloy tube samples with some artificial defects were provided for measurements. To clarify the locations in axial and azimuthal directions, types and dimensions of the provided artificial defects, measured signals from eddy current test were analysed in comparison with the known defects on the calibration tube. As a result, fourteen defects were determined from the measurements. Then, the location, the type and the relative dimension of them were also revealed. The results of those eddy current test are described in this paper. (author)

  1. Low tube voltage dual source computed tomography to reduce contrast media doses in adult abdomen examinations: A phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Thor, Daniel [Department of Diagnostic Medical Physics, Karolinska University Hospital, Stockholm 14186 (Sweden); Brismar, Torkel B., E-mail: torkel.brismar@gmail.com; Fischer, Michael A. [Department of Clinical Science, Intervention and Technology at Karolinska Institutet and Department of Radiology, Karolinska University Hospital in Huddinge, Stockholm 14186 (Sweden)

    2015-09-15

    Purpose: To evaluate the potential of low tube voltage dual source (DS) single energy (SE) and dual energy (DE) computed tomography (CT) to reduce contrast media (CM) dose in adult abdominal examinations of various sizes while maintaining soft tissue and iodine contrast-to-noise ratio (CNR). Methods: Four abdominal phantoms simulating a body mass index of 16 to 35 kg/m{sup 2} with four inserted syringes of 0, 2, 4, and 8 mgI/ml CM were scanned using a 64-slice DS-CT scanner. Six imaging protocols were used; one single source (SS) reference protocol (120 kV, 180 reference mAs), four low kV SE protocols (70 and 80 kV using both SS and DS), and one DE protocol at 80/140 kV. Potential CM reduction with unchanged CNRs relative to the 120 kV protocol was calculated along with the corresponding increase in radiation dose. Results: The potential contrast media reductions were determined to be approximately 53% for DS 70 kV, 51% for SS 70 kV, 44% for DS 80 kV, 40% for SS 80 kV, and 20% for DE (all differences were significant, P < 0.05). Constant CNR could be achieved by using DS 70 kV for small to medium phantom sizes (16–26 kg/m{sup 2}) and for all sizes (16–35 kg/m{sup 2}) when using DS 80 kV and DE. Corresponding radiation doses increased by 60%–107%, 23%–83%, and 6%–12%, respectively. Conclusions: DS single energy CT can be used to reduce CM dose by 44%–53% with maintained CNR in adult abdominal examinations at the cost of an increased radiation dose. DS dual-energy CT allows reduction of CM dose by 20% at similar radiation dose as compared to a standard 120 kV single source.

  2. Reduce chest pain using modified silicone fluted drain tube for chest drainage after video-assisted thoracic surgery (VATS) lung resection.

    Science.gov (United States)

    Li, Xin; Hu, Bin; Miao, Jinbai; Li, Hui

    2016-02-01

    The aim of this study was to assess the feasibility, efficacy and safety of a modified silicone fluted drain tube after video-assisted thoracic surgery (VATS) lung resection. The prospective randomized study included 50 patients who underwent VATS lung resection between March 2015 and June 2015. Eligible patients were randomized into two groups: experimental group (using the silicone fluted drain tubes for chest drainage) and control group (using standard drain tubes for chest drainage). The volume and characteristics of drainage, postoperative (PO) pain scores and hospital stay were recorded. All patients received standard care during hospital admission. In accordance with the exit criteria, three patients were excluded from study. The remaining 47 patients included in the final analysis were divided into two groups: experiment group (N=24) and control group (N=23). There was no significant difference between the two groups in terms of age, sex, height, weight, clinical diagnosis and type of surgical procedure. There was a trend toward less PO pain in experimental group on postoperative day (POD) 1, with a statistically significant difference. Patients in experimental group had a reduced occurrence of fever [temperature (T) >37.4 °C] compared to the control group. The silicone fluted drain tube is feasible and safe and may relieve patient PO pain and reduce occurrence of fever without the added risk of PO complications.

  3. Dose reduction in multi-slice CT of the heart by use of ECG-controlled tube current modulation (''ECG pulsing''): phantom measurements

    International Nuclear Information System (INIS)

    Poll, L.W.; Cohnen, M.; Brachten, S.; Moedder, U.; Ewen, K.

    2002-01-01

    To evaluate the effect of ECG-controlled tube current modulation on radiation exposure in retrospectively-ECG-gated multislice CT (MSCT) of the heart. Material and methods: Three different cardiac MSCT protocols with different slice collimation (4 x 1, and 4 x 2.5 mm), and a pitch-factor of 1.5 and 1.8 were investigated at a multi-slice CT scanner Somatom Volume Zoom, Siemens. An anthropomorphic Alderson-Rando phantom was equipped with LiF-Thermoluminescence dosimeters at several organ sites, and effective doses were calculated using ICRP-weighting factors. Scan protocols were performed with ECG-controlled tube current modulation ('ECG pulsing') at two different heart rates (60 and 80 bpm). These data were compared to previous data from MSCT of the heart without use of 'ECG pulsing'. Results: Radiation exposure with (60 bpm) and without tube current modulation using a 2.5 mm collimation was 1.8 mSv and 2.9 mSv for females, and 1.5 mSv and 2.4 mSv for males, respectively. For protocols using a 1 mm collimation with a pitch-factor of 1.5 (1.8), radiation exposure with and without tube current modulation was 5.6 (6.3) mSv and 9.5 (11.2) mSv for females, and 4.6 (5.2) mSv and 7.7 (9.2) mSv for males, respectively. At higher heart rates (80 bpm) radiation exposure is increased from 1.5-1.8 mSv to 1.8-2.1 mSv, using the 2.5 mm collimation, and from 4.6-5.6 mSv to 5.9-7.2 mSv, for protocols using 1 mm collimation. Conclusions: The ECG-controlled tube current modulation allows a dose reduction of 37% to 44% when retrospectively ECG-gated MSCT of the heart is performed. The tube current - as a function over time - and therefore the radiation exposure is dependent on the heart rate. (orig.) [de

  4. High temperature ceramic-tubed reformer

    Science.gov (United States)

    Williams, Joseph J.; Rosenberg, Robert A.; McDonough, Lane J.

    1990-03-01

    The overall objective of the HiPHES project is to develop an advanced high-pressure heat exchanger for a convective steam/methane reformer. The HiPHES steam/methane reformer is a convective, shell and tube type, catalytic reactor. The use of ceramic tubes will allow reaction temperature higher than the current state-of-the-art outlet temperatures of about 1600 F using metal tubes. Higher reaction temperatures increase feedstock conversion to synthesis gas and reduce energy requirements compared to currently available radiant-box type reformers using metal tubes. Reforming of natural gas is the principal method used to produce synthesis gas (primarily hydrogen and carbon monoxide, H2 and CO) which is used to produce hydrogen (for refinery upgrading), methanol, as well as several other important materials. The HiPHES reformer development is an extension of Stone and Webster's efforts to develop a metal-tubed convective reformer integrated with a gas turbine cycle.

  5. Reducing AC-Winding Losses in High-Current High-Power Inductors

    DEFF Research Database (Denmark)

    Nymand, Morten; Madawala, Udaya K.; Andersen, Michael Andreas E.

    2009-01-01

    Foil windings are preferable in high-current high-power inductors to realize compact designs and to reduce dc-current losses. At high frequency, however, proximity effect will cause very significant increase in ac resistance in multi-layer windings, and lead to high ac winding losses. This paper ...

  6. Eddy current magnetic bias x-probe qualification and inspection of steam generator Monel 400 tubing in Pickering Nuclear Generating Station

    International Nuclear Information System (INIS)

    Lepine, B.A.; Van Langen, J.; Obrutsky, L.

    2006-01-01

    This paper presents an overview of the x-probe MB 350 eddy current inspection array probe, for detection of open OD axial crack-like flaws in Monel 400 tubes at Pickering Nuclear Generating Station. This report contains a selection of inspection results from the field inspections performed with this probe during the 2003 and 2004 period at Pickering Nuclear Generating Station A and B. During the 2003 in-service eddy current inspection results of Pickering Nuclear Generating Station A (PNGS-A) Unit 2, a 13 mm (0.5 inch) long axial indication was detected by the CTR1 bobbin and CTR2-C4 array probes in Tube R25-C52 of Steam Generator (SG) 11 in the hot leg sludge pile region. An experimental magnetic bias X-probe, specially designed by Zetec for inspection of Monel 400 tubing, was deployed and the indication was characterized as a potential out diameter (OD) axially oriented crack. Post-inspection tube pulling and destructive examination confirmed the presence of an Environmentally Assisted Crack (EAC), approximately 80% deep and 13mm long. Due to the significance of this discovery, Ontario Power Generation (OPG) requested AECL to initiate a program for qualification of the X-probe MB 350 for the detection of OD axial cracks in medium to high magnetic permeability μ r Monel 400 PNGS-A and B steam generator tubing at different locations. The X-probe MB 350 subsequently has been deployed as a primary inspection probe for crack detection for PNGS steam generators. (author)

  7. Educational Quality of YouTube Videos in Thumb Exercises for Carpometacarpal Osteoarthritis: A Search on Current Practice.

    Science.gov (United States)

    Villafañe, Jorge Hugo; Cantero-Tellez, Raquel; Valdes, Kristin; Usuelli, Federico Giuseppe; Berjano, Pedro

    2017-09-01

    Conservative treatments are commonly performed therapeutic interventions for the management of carpometacarpal (CMC) joint osteoarthritis (OA). Physical and occupational therapies are starting to use video-based online content as both a patient teaching tool and a source for treatment techniques. YouTube is a popular video-sharing website that can be accessed easily. The purpose of this study was to analyze the quality of content and potential sources of bias in videos available on YouTube pertaining to thumb exercises for CMC OA. The YouTube video database was systematically searched using the search term thumb osteoarthritis and exercises from its inception to March 10, 2017. Authors independently selected videos, conducted quality assessment, and extracted results. A total of 832 videos were found using the keywords. Of these, 10 videos clearly demonstrated therapeutic exercise for the management of CMC OA. In addition, the top-ranked video found by performing a search of "views" was a video with more than 121 863 views uploaded in 2015 that lasted 12.33 minutes and scored only 2 points on the Global Score for Educational Value rating scale. Most of the videos viewed that described conservative interventions for CMC OA management have a low level of evidence to support their use. Although patients and novice hand therapists are using YouTube and other online resources, videos that are produced by expert hand therapists are scarce.

  8. Improvement in reliability and accuracy of heater tube eddy current testing by integration with an appropriate destructive test

    International Nuclear Information System (INIS)

    Giovanelli, F.; Gabiccini, S.; Tarli, R.; Motta, P.

    1988-01-01

    A specially developed destructive test is described showing how the reliability and accuracy of a non-destructive technique can be improved if it is suitably accompanied by an appropriate destructive test. The experiment was carried out on samples of AISI 304L tubes from the low-pressure (LP) preheaters of a BWR 900 MW nuclear plant. (author)

  9. SU-F-207-03: Dosimetric Effect of the Position of Arms in Torso CT Scan with Tube Current Modulation

    International Nuclear Information System (INIS)

    Liu, H; Gao, Y; Xu, X; Zhuo, W; Wu, J

    2015-01-01

    Purpose: To evaluate the patient organ dose differences between the arms-raised and arms-lowered postures in Torso multidetector computed tomography (MDCT) scan protocols with tube current modulation (TCM). Methods: Patient CT organ doses were simulated using the Monte Carlo method with human phantoms and a validated CT scanner model. A set of adult human phantoms with arms raised and arms lowered postures were developed using advanced BREP-based mesh surface geometries. Organ doses from routine Torso scan protocols such as chest, abdomen-pelvis, and CAP scans were simulated. The organ doses differences caused by two different posutres were investigated when tube current modulation (TCM) were applied during the CT scan. Results: With TCM applied, organ doses of all the listed organs of arms-lowered posture phantom are larger than those of arms raised phantom. The dose difference for most of the organs or tissues are larger than 50%, and the skin doses difference for abdomen-pelvis scan even reaches 112.03%. This is due to the fact that the tube current for patient with arms-lowered is much higher than for the arms raised posture. Conclusion: Considering CT scan with TCM, which is commonly applied clinically, patients who could not raise their arms will receive higher radiation dose than the arms raised patient, with dose differences for some tissues such as the skin being larger than 100%. This is due to the additional tube current necessary to penetrate the arms while maintaining consistent image quality. National Nature Science Foundation of China(No.11475047)

  10. Development of a system for monitoring and diagnosis of steam generator tubes using artificial intelligence techniques on Eddy Current Test signals

    International Nuclear Information System (INIS)

    Mesquita, Roberto Navarro de; Ting, Daniel Kao Sun; Lopez, Luis A. Negro M.; Upadhyaya, Belle R.

    2002-01-01

    New classification and feature extraction methods for steam generator tube defects are being developed by IPEN/CNEN-SP in cooperation with UTK to improve a monitoring and diagnosis system for classification and characterization of steam generator tube defects using Eddy Current Testing (ECT) signals. The first methodology being developed uses a set of feature extraction methods applied to different tube defect type ECT signals and each obtained feature vector is projected into a bi-dimensional map obtained by a Self-Organizing Map neural network. This methodology allows an optimal feature extraction method selection for the defect type classification. Other approach is being developed using tubes with different manufactured defect types which are tested using MIZ-17ET equipment with 4 sets of probes (two different diameter). A fuzzy inference system will be used to build a knowledge base for these defects. These methodology and algorithms will be integrated into an automated diagnosis system being developed with UTK, which is designed to read both on-line acquired data, as well as stored data files. These commercial software tools are the ones usually utilized in nuclear power plants. (author)

  11. Development of a system for monitoring and diagnosis of steam generator tubes using artificial intelligence techniques on Eddy Current Test signals

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Roberto Navarro de [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Monitoracao e Diagnostico]|[Sao Paulo Univ., SP (Brazil); Ting, Daniel Kao Sun [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Monitoracao e Diagnostico; Cabral, Eduardo Lobo C. [Sao Paulo Univ., SP (Brazil); Lopez, Luis A. Negro M. [Faculdade de Engenharia Industrial, Sao Bernardo do Campo, SP (Brazil); Upadhyaya, Belle R. [Tennessee Univ., Knoxville, TN (United States)

    2002-07-01

    New classification and feature extraction methods for steam generator tube defects are being developed by IPEN/CNEN-SP in cooperation with UTK to improve a monitoring and diagnosis system for classification and characterization of steam generator tube defects using Eddy Current Testing (ECT) signals. The first methodology being developed uses a set of feature extraction methods applied to different tube defect type ECT signals and each obtained feature vector is projected into a bi-dimensional map obtained by a Self-Organizing Map neural network. This methodology allows an optimal feature extraction method selection for the defect type classification. Other approach is being developed using tubes with different manufactured defect types which are tested using MIZ-17ET equipment with 4 sets of probes (two different diameter). A fuzzy inference system will be used to build a knowledge base for these defects. These methodology and algorithms will be integrated into an automated diagnosis system being developed with UTK, which is designed to read both on-line acquired data, as well as stored data files. These commercial software tools are the ones usually utilized in nuclear power plants. (author)

  12. An Analysis of the Loads on and Dynamic Response of a Floating Flexible Tube in Waves and Currents

    Science.gov (United States)

    2014-05-09

    the tube about 4.57 meters. The CFD code associated with the SolidWorks Flow Simulation tool was applied for this application. Flow Simulation uses...Liquid-Filled Membrane Structure in Waves," Journal of Fluids and Structures, no. 9, pp. 937-956, 1995. [16] SolidWorks , " Flow Simulation 2012...influence of Reynolds number on the drag coefficient. Simulations were performed with the 100% full (solid) model with flow velocities that yielded

  13. Scale-up of counter-current chromatography: demonstration of predictable isocratic and quasi-continuous operating modes from the test tube to pilot/process scale.

    Science.gov (United States)

    Sutherland, Ian; Hewitson, Peter; Ignatova, Svetlana

    2009-12-11

    Predictable scale-up from test tube derived distribution ratios and analytical-scale sample loading optimisation is demonstrated using a model sample system of benzyl alcohol and p-cresol in a heptane:ethyl acetate:methanol:water phase system with the new 18 L Maxi counter-current chromatography centrifuge. The versatility of having a liquid stationary phase with its high loading capacity and flexible operating modes is demonstrated at two different scales by separating and concentrating target compounds using a mixture of caffeine, vanillin, naringenin and carvone using a quasi-continuous technique called intermittent counter-current extraction.

  14. A prospective evaluation of contrast and radiation dose and image quality in cardiac CT in children with complex congenital heart disease using low-concentration iodinated contrast agent and low tube voltage and current.

    Science.gov (United States)

    Hou, Qiao-Ru; Gao, Wei; Sun, Ai-Min; Wang, Qian; Qiu, Hai-Sheng; Wang, Fang; Hu, Li-Wei; Li, Jian-Ying; Zhong, Yu-Min

    2017-02-01

    To the assess image quality, contrast dose and radiation dose in cardiac CT in children with congenital heart disease (CHD) using low-concentration iodinated contrast agent and low tube voltage and current in comparison with standard dose protocol. 110 patients with CHD were randomized to 1 of the 2 scan protocols: Group A (n = 45) with 120 mA tube current and contrast agent of 270 mgI/ml in concentration (Visipaque ™ ; GE Healthcare Ireland, Co., Cork, UK); and Group B (n = 65) with the conventional 160 mA and 370 mgI/ml concentration contrast (Iopamiro ® ; Shanghai Bracco Sine Pharmaceutical Corp Ltd, Shanghai, China). Both groups used 80 kVp tube voltage and were reconstructed with 70% adaptive statistical iterative reconstruction algorithm. The CT value and noise in aortic arch were measured and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. A five-point scale was used to subjectively evaluate image quality. Contrast and radiation dose were recorded. There was no difference in age and weight between the two groups (all p > 0.05). The iodine load and radiation dose in Group A were statistically lower (3976 ± 747 mgI vs 5763 ± 1018 mgI in iodine load and 0.60 ± 0.08 mSv vs 0.77 ± 0.10 mSv in effective dose; p  0.05), and with good agreement between the two observers. Comparing the surgery results, the diagnostic accuracy for extracardiac and intracardiac defects for Group A was 96% and 92%, respectively, while the corresponding numbers for Group B were 95% and 93%. Compared with the standard dose protocol, the use of low tube voltage (80 kVp), low tube current (120 mA) and low-concentration iodinated contrast agent (270 mgI/ml) enables a reduction of 30% in iodine load and 22% in radiation dose while maintaining compatible image quality and diagnostic accuracy. Advances in knowledge: The new cardiac CT scanning protocol can largely reduce the adverse effects of

  15. Damping Resonant Current in a Spark-Gap Trigger Circuit to Reduce Noise

    Science.gov (United States)

    2009-06-01

    DAMPING RESONANT CURRENT IN A SPARK- GAP TRIGGER CIRCUIT TO REDUCE NOISE E. L. Ruden Air Force Research Laboratory, Directed Energy Directorate, AFRL...REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Damping Resonant Current In A Spark- Gap Trigger Circuit To Reduce Noise 5a...thereby triggering 2 after delay 0, is 1. Each of the two rail- gaps (represented by 2) is trig- gered to close after the spark- gap (1) in the

  16. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... search for current job openings visit HHS USAJobs Home >> NEI YouTube Videos >> NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia Animations Blindness Cataract ...

  17. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... search for current job openings visit HHS USAJobs Home » NEI YouTube Videos » NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia Animations Blindness Cataract ...

  18. Development of Interior Permanent Magnet Motors with Concentrated Windings for Reducing Magnet Eddy Current Loss

    Science.gov (United States)

    Yamazaki, Katsumi; Kanou, Yuji; Fukushima, Yu; Ohki, Shunji; Nezu, Akira; Ikemi, Takeshi; Mizokami, Ryoichi

    In this paper, we present the development of interior magnet motors with concentrated windings, which reduce the eddy current loss of the magnets. First, the mechanism of the magnet eddy current loss generation is investigated by a simple linear magnetic circuit. Due to the consideration, an automatic optimization method using an adaptive finite element method is carried out to determine the stator and rotor shapes, which decrease the eddy current loss of the magnet. The determined stator and rotor are manufactured in order to proof the effectiveness by the measurement.

  19. Strain reduced critical current in Bi-2223/Ag superconductors under axial tension and compression

    International Nuclear Information System (INIS)

    Haken, B. ten; Godeke, A.; Kate, H.H.J. ten

    1997-01-01

    The critical current of Ag sheathed Bi(Pb)SrCaCuO-2223 tape conductors is investigated as a function of various strain components. A reduction of the critical current occurs due to both tensile or a compressive strain. The critical current reduction is qualitatively similar with the results as observed in Bi-2212 conductors. An axial compression leads to an immediate critical current reduction. The critical current in an axially elongated sample remains nearly constant up to a certain limit typically close to 0.3% strain. For a larger elongation the critical current reduces rapidly. A transverse pressure acting on the tape surface leads also to an irreversible critical current reduction. This behavior is compared with the influence of an axial compression with an effective Young's modulus. The deformation induced critical current reductions in Bi-2223 conductors can be described by a model that is already proposed for Bi-2212 conductors. This model is based on the irreversible nature of the critical current reduction due to a certain deformation

  20. Non-square quantum well growth for reduced threshold current in ...

    African Journals Online (AJOL)

    This paper presents calculations demonstrating that non-square quantum well growth (well shaping) can result in reduced threshold current for tensilely strained quantum well bipolar diode lasers operating at 1.52ìm m. Calculations of subband structure, optical matrix elements and laser gain are performed for arbitrarily ...

  1. MO-F-CAMPUS-I-04: Patient Eye-Lens Dose Reduction in Routine Brain CT Examinations Using Organ-Based Tube Current Modulation and In-Plane Bismuth Shielding

    International Nuclear Information System (INIS)

    Tsai, Hui-Yu; Liao, Ying-Lan; Lai, Nan-Ku; Chen, Tou-Rong; Chen, Jun-Rong

    2015-01-01

    Purpose: The purpose of this study is to assess eye-lens dose for patients who underwent brain CT examinations using two dose reduction Methods: organ-based tube current modulation (OBTCM) and in-plane bismuth shielding method. Methods: This study received institutional review board approval; written informed consent to participate was obtained from all patients. Ninety patients who underwent the routine brain CT examination were randomly assigned to three groups, ie. routine, OBTCM, and bismuth shield. The OBTCM technique reduced the tube current when the X-ray tube rotates in front of patients’ eye-lens region. The patients in the bismuth shield group were covered one-ply bismuth shield in the eyes’ region. Eye-lens doses were measured using TLD-100H chips and the total effective doses were calculated using CT-Expo according to the CT scanning parameters. The surface doses for patients at off-center positions were assessed to evaluate the off-centering effect. Results: Phantom measurements indicates that OBTCM technique could reduced by 26% to 28% of the surface dose to the eye lens, and increased by 25% of the surface dose at the opposed incident direction at the angle of 180°. Patients’ eye-lens doses were reduced 16.9% and 30.5% dose of bismuth shield scan and OBTCM scan, respectively compared to the routine scan. The eye-lens doses were apparently increased when the table position was lower than isocenter. Conclusion: Reducing the dose to the radiosensitive organs, such as eye lens, during routine brain CT examinations could lower the radiation risks. The OBTCM technique and in-plane bismuth shielding could be used to reduce the eye-lens dose. The eye-lens dose could be effectively reduced using OBTCM scan without interfering the diagnostic image quality. Patient position relative the CT gantry also affects the dose level of the eye lens. This study was supported by the grants from the Ministry of Science and Technology of Taiwan (MOST103-2314-B-182

  2. Isolation of sutherlandins A, B, C and D from Sutherlandia frutescens (L.) R. Br. by counter-current chromatography using spiral tubing support rotors.

    Science.gov (United States)

    Chen, Cuiping; Folk, William R; Lazo-Portugal, Rodrigo; Finn, Thomas M; Knight, Martha

    2017-07-28

    Spiral countercurrent-chromatography has great potential for improving the capacity and efficiency of purification of secondary metabolites, and here we describe applications useful for the isolation of flavonoids from the widely used South African medicinal plant, Sutherlandia frutescens (L.) R. Br. In the spiral tubing support rotor, STS-4 for high-speed counter-current chromatography, several polar butanol aqueous solvent systems were selected using a logK plot, and the novel flavonol glycosides (sutherlandins A-D) were well separated by the optimized solvent system (ethyl acetate:n-butanol:acetic acid:water; 5:1:0.3:6 by vol.). The yield of purified flavonoids from 0.9g extract varied from 8.6mg to 54mg of the sutherlandins for a total of 85.3mg. The same extract was fractionated in the new STS-12 rotor of the same outside dimensions but with more radial channels forming 12 loops of the tubing instead of 4. The rotor holds more layers and increased length of tubing. From 0.9g extract the STS-12 rotor yielded more recovery of 110.4mg total with amounts varying from 11.2mg to 64mg of the sutherlandins and apparent increased separation efficiency as noted by less volume of each fraction peak. Thus from 1-g amounts of extract, good recovery of the flavonoids was achieved in the butanol aqueous solvent system. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Development and validation of a simulation tool dedicated to eddy current non destructive testing of tubes; Developpement d'un modele electromagnetique 3D pour la simulation du controle par Courants de Foucault de tubes en fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Reboud, Ch

    2006-09-15

    Eddy current testing (ECT) technique is widely used in industrial fields such as iron and steel industry. Dedicated simulation tools provide a great assistance for the optimisation of ECT processes. CEA and the Vallourec Research Center have collaborated in order to develop a simulation tool of ECT of tubes. The volume integral method has been chosen for the resolution of Maxwell equations in a stratified medium, in order to get accurate results with a computation time short enough to carry out optimisation or inversion procedures. A fast model has been developed for the simulation of ECT of non magnetic tubes using specific external probes. New flaw geometries have been modelled: holes and notches with flat bottom. Validations of the developments, which have been integrated to the CIVA platform, have been carried out using experimental data recorded in laboratory conditions and in. industrial conditions, successively. The integral equations derived are solved using the Galerkin variant of the method of moments with pulse functions as projection functions. In order to overcome some memory limitations, other projection functions have been considered. A new discretization scheme based on non-uniform B-Splines of degree 1 or 2 has been implemented, which constitutes an original contribution to the existing literature. The decrease of the mesh size needed to get a given accuracy on the result may lead to the simulation of more complex ECT configurations. (author)

  4. Influence of Tube Current Settings on Diagnostic Detection of Root Fractures Using Cone-beam Computed Tomography: An In Vitro Study.

    Science.gov (United States)

    Tangari-Meira, Ricardo; Vancetto, José Ricardo; Dovigo, Lívia Nordi; Tosoni, Guilherme Monteiro

    2017-10-01

    This study assessed the influence of tube current settings (milliamperes [mA]) on the diagnostic detection of root fractures (RFs) using cone-beam computed tomographic (CBCT) imaging. Sixty-eight human anterior and posterior teeth were submitted to root canal preparation, and 34 root canals were filled. The teeth were divided into 2 groups: the control group and the fractured group. RFs were induced using a universal mechanical testing machine; afterward, the teeth were placed in a phantom. Images were acquired using a Scanora 3DX unit (Soredex, Tuusula, Finland) with 5 different mA settings: 4.0, 5.0, 6.3, 8.0, and 10.0. Two examiners (E1 and E2) classified the images according to a 5-point confidence scale. Intra- and interexaminer reproducibility was assessed using the kappa statistic; diagnostic performance was assessed using the area under the receiver operating characteristic curve (AUROC). Intra- and interexaminer reproducibility showed substantial (κE1 = 0.791 and κE2 = 0.695) and moderate (κE1 × E2 = 0.545) agreement, respectively. AUROC was significantly higher (P ≤ .0389) at 8.0 and 10.0 mA and showed no statistical difference between the 2 tube current settings. Tube current has a significant influence on the diagnostic detection of RFs in CBCT images. Despite the acceptable diagnosis of RFs using 4.0 and 5.0 mA, those settings had lower discrimination abilities when compared with settings of 8.0 and 10.0 mA. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Design of Controller for Reducing In-Rush Current of Single-Phase Induction Motor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Su Kang; Baek, Hyung Lae; Lee, Sang Il [Chosun University, Kwangju (Korea)

    2001-05-01

    During an AC motor's start-up accelerating period, a large amount of current is required to reach to the rating speed. This is called in-rush current. This peak in-rush current can be more than about several times the operating or steady-state current in the full load rating of the motor. In-rush current is present in both and electronic ballasts. The main area of concern is the tripping of circuit breaker and fuses which can affect electrical system components From this, we can see that the electrical power controllers will be rather concerned, since they have to supply the actual current necessary to start the motor. This paper presents a new method to reducing in-rush current and energy saving of the single-phase induction motor used in air-conditioner. It can be obtained that proposed system is low cost and small size as compared with other controller. Experiments are focused on a capacitor starting single-phase induction motor. The optimal power saving and in-rush current limiting by phase angle control are verified by experimental results. Also, auxiliary winding was controlled by electronic starting switch. (author). 10 refs., 13 figs., 2 tabs.

  6. A comparative Thermal Analysis of conventional parabolic receiver tube and Cavity model tube in a Solar Parabolic Concentrator

    Science.gov (United States)

    Arumugam, S.; Ramakrishna, P.; Sangavi, S.

    2018-02-01

    Improvements in heating technology with solar energy is gaining focus, especially solar parabolic collectors. Solar heating in conventional parabolic collectors is done with the help of radiation concentration on receiver tubes. Conventional receiver tubes are open to atmosphere and loose heat by ambient air currents. In order to reduce the convection losses and also to improve the aperture area, we designed a tube with cavity. This study is a comparative performance behaviour of conventional tube and cavity model tube. The performance formulae were derived for the cavity model based on conventional model. Reduction in overall heat loss coefficient was observed for cavity model, though collector heat removal factor and collector efficiency were nearly same for both models. Improvement in efficiency was also observed in the cavity model’s performance. The approach towards the design of a cavity model tube as the receiver tube in solar parabolic collectors gave improved results and proved as a good consideration.

  7. Comparison of standardized uptake values measured on 18F-NaF PET/CT scans using three different tube current intensities

    OpenAIRE

    Agnes Araujo Valadares; Paulo Schiavom Duarte; Eduardo Bechtloff Woellner; George Barberio Coura-Filho; Marcelo Tatit Sapienza; Carlos Alberto Buchpiguel

    2015-01-01

    Objective: To analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on 18FNaF PET/CT scans. Materials and Methods: A total of 254 18F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses ...

  8. A method of multi-crack shape identification from eddy current testing signals of steam generator tubes including support plates as noise sources

    International Nuclear Information System (INIS)

    Nagaya, Yoshiaki; Endo, Hisashi; Takagi, Toshiyuki; Uchimoto, Tetsuya

    2005-01-01

    This paper deals with identifying multiple cracks from eddy current testing (ECT) signals obtained in a steam generator tube with a support plate and deposits. Assume two-dimensionally scanned ECT signals to be a picture image, then the signal processing by a multi-frequency technique eliminates noise caused by the support plate and deposits. A template matching with help of genetic algorithms detects number and positions of cracks from the image after the signal processing. Inverse analysis estimates the crack profile based on the predicted position of cracks. The number and positions of the cracks are sufficiently well predicted. Crack shape reconstructions are achieved with a satisfactory degree of accuracy. (author)

  9. Electrical current mediated interconversion between graphene oxide to reduced grapene oxide

    Science.gov (United States)

    Teoh, H. F.; Tao, Y.; Tok, E. S.; Ho, G. W.; Sow, C. H.

    2011-04-01

    In this work, we demonstrate that graphene oxide (GO) can be reversibly converted to reduced-graphene-oxide (rGO) through the use of electric current. Strong electric field could cause ionization of water molecules in air to generate H+ ions at cathode, causing GO to be reduced. When the bias is reversed, the same electrode becomes positive and OH- ions are produced. According to Le Chatelier Principle, it then favors the reverse reaction, converting rGO back to GO, GO+2H++2e-=>rGO+H2O. X-ray spectroscopy and Raman spectroscopy were carried to verify the conversion reversibility in the reversed process.

  10. Development Of Design Equations For A Square-tube Subbase Supporting A Shaft-mounted Speed Reducer

    OpenAIRE

    Brown III, William E.

    2002-01-01

    Shaft mounted speed reducers are used in material handling applications, such as conveyor systems for transporting ore out of mine shafts. A subbase joins the reducer with an electric motor, and serves to limit the misalignment between the motor shaft and the reducer input shaft. The entire assembly is supported at two points: the axis of rotation of the reducer output shaft, which is fixed, and a clevis-pin joint under the motor, which prevents rotation of the assembly about the reducer ou...

  11. Reducing iodine load in hepatic CT for patients with chronic liver disease with a combination of low-tube-voltage and adaptive statistical iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Noda, Yoshifumi [Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Kanematsu, Masayuki, E-mail: masa_gif@yahoo.co.jp [Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Department of Radiology Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Goshima, Satoshi; Kondo, Hiroshi; Watanabe, Haruo; Kawada, Hiroshi; Kawai, Nobuyuki; Tanahashi, Yukichi [Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Miyoshi, Toshiharu R.T. [Department of Radiology Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Bae, Kyongtae T. [Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, PA (United States)

    2015-01-15

    Highlights: • 80 kVp CT scanning was successfully applied to the hepatic imaging. • Iodine contrast material load was reduced to 400 mg iodine/kg. • Image quality and the detectability of HCCs were maintained. - Abstract: Purpose: To prospectively assess the effect of reduced iodine load to contrast enhancement, image quality, and detectability of hepatocellular carcinomas (HCCs) in hepatic CT with a combination of 80 kVp tube voltage setting and adaptive statistical iterative reconstruction (ASIR) technique in patients with chronic liver disease. Materials and methods: This HIPAA-compliant study was approved by our institutional review board and written informed consent was obtained in all patients. During a recent 9-month period, 170 consecutive patients (114 men and 56 women; age range, 40–85 years; mean, 67.7 years) with suspected chronic liver diseases were randomized into three CT groups according to the following iodine-load and tube-voltage protocols: 600 milligram per kilogram body weight (mg/kg) iodine load and 120 peak kilovolt (kVp) tube voltage setting (600-120 group), 500 mg/kg and 80 kVp (500-80 group), and 400 mg/kg and 80 kVp (400-80 group). Analysis of variance was conducted to evaluate differences in CT number, background noise, signal-to-noise ratio (SNR), effective dose, HCC-to-liver contrast-to-noise ratio (CNR), and figure of merit (FOM). Sensitivity, specificity, and area under the receiver-operating-characteristic curve (AUC) were compared to assess the detectability of HCCs. Results: Vascular and hepatic enhancement in the 400-80 and 500-80 groups was comparable to or greater than that in the 600-120 group (P < .05). Subjective image quality was comparable among the three groups. Sensitivity, specificity, and AUC for detecting HCCs were comparable among the groups. The effective dose was kept low (3.3–4.1 mSv) in all three groups. Conclusion: Iodine load can be reduced by 33% in CT of the liver with a combination of 80 kVp tube

  12. photomultiplier tubes

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  13. photomultiplier tube

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  14. Reduced Sodium Current in the Lateral Ventricular Wall Induces Inferolateral J-Waves.

    Science.gov (United States)

    Meijborg, Veronique M F; Potse, Mark; Conrath, Chantal E; Belterman, Charly N W; De Bakker, Jacques M T; Coronel, Ruben

    2016-01-01

    J-waves in inferolateral leads are associated with a higher risk for idiopathic ventricular fibrillation. We aimed to test potential mechanisms (depolarization or repolarization dependent) responsible for inferolateral J-waves. We hypothesized that inferolateral J-waves can be caused by regional delayed activation of myocardium that is activated late during normal conditions. Computer simulations were performed to evaluate how J-point elevation is influenced by reducing sodium current conductivity (GNa), increasing transient outward current conductivity (Gto), or cellular uncoupling in three predefined ventricular regions (lateral, anterior, or septal). Two pig hearts were Langendorff-perfused with selective perfusion with a sodium channel blocker of lateral or anterior/septal regions. Volume-conducted pseudo-electrocardiograms (ECG) were recorded to detect the presence of J-waves. Epicardial unipolar electrograms were simultaneously recorded to obtain activation times (AT). Simulation data showed that conduction slowing, caused by reduced sodium current, in lateral, but not in other regions induced inferolateral J-waves. An increase in transient outward potassium current or cellular uncoupling in the lateral zone elicited slight J-point elevations which did not meet J-wave criteria. Additional conduction slowing in the entire heart attenuated J-waves and J-point elevations on the ECG, because of masking by the QRS. Experimental data confirmed that conduction slowing attributed to sodium channel blockade in the left lateral but not in the anterior/septal ventricular region induced inferolateral J-waves. J-waves coincided with the delayed activation. Reduced sodium current in the left lateral ventricular myocardium can cause inferolateral J-waves on the ECG.

  15. Simulated Design Strategies for SPECT Collimators to Reduce the Eddy Currents Induced by MRI Gradient Fields

    Science.gov (United States)

    Samoudi, Amine M.; Van Audenhaege, Karen; Vermeeren, Günter; Verhoyen, Gregory; Martens, Luc; Van Holen, Roel; Joseph, Wout

    2015-10-01

    Combining single photon emission computed tomography (SPECT) with magnetic resonance imaging (MRI) requires the insertion of highly conductive SPECT collimators inside the MRI scanner, resulting in an induced eddy current disturbing the combined system. We reduced the eddy currents due to the insert of a novel tungsten collimator inside transverse and longitudinal gradient coils. The collimator was produced with metal additive manufacturing, that is part of a microSPECT insert for a preclinical SPECT/MRI scanner. We characterized the induced magnetic field due to the gradient field and adapted the collimators to reduce the induced eddy currents. We modeled the x-, y-, and z-gradient coil and the different collimator designs and simulated them with FEKO, a three-dimensional method of moments / finite element methods (MoM/FEM) full-wave simulation tool. We used a time analysis approach to generate the pulsed magnetic field gradient. Simulation results show that the maximum induced field can be reduced by 50.82% in the final design bringing the maximum induced magnetic field to less than 2% of the applied gradient for all the gradient coils. The numerical model was validated with measurements and was proposed as a tool for studying the effect of a SPECT collimator within the MRI gradient coils.

  16. Automatic exposure control in CT: the effect of patient size, anatomical region and prescribed modulation strength on tube current and image quality

    International Nuclear Information System (INIS)

    Papadakis, Antonios E.; Perisinakis, Kostas; Damilakis, John

    2014-01-01

    To study the effect of patient size, body region and modulation strength on tube current and image quality on CT examinations that use automatic tube current modulation (ATCM). Ten physical anthropomorphic phantoms that simulate an individual as neonate, 1-, 5-, 10-year-old and adult at various body habitus were employed. CT acquisition of head, neck, thorax and abdomen/pelvis was performed with ATCM activated at weak, average and strong modulation strength. The mean modulated mAs (mAs mod ) values were recorded. Image noise was measured at selected anatomical sites. The mAs mod recorded for neonate compared to 10-year-old increased by 30 %, 14 %, 6 % and 53 % for head, neck, thorax and abdomen/pelvis, respectively, (P mod was lower than the preselected mAs with the exception of the 10-year-old phantom. In paediatric and adult phantoms, the mAs mod ranged from 44 and 53 for weak to 117 and 93 for strong modulation strength, respectively. At the same exposure parameters image noise increased with body size (P < 0.05). The ATCM system studied here may affect dose differently for different patient habitus. Dose may decrease for overweight adults but increase for children older than 5 years old. Care should be taken when implementing ATCM protocols to ensure that image quality is maintained. circle ATCM efficiency is related to the size of the patient's body. (orig.)

  17. Comparison of standardized uptake values measured on {sup 18}F-NaF PET/CT scans using three different tube current intensities

    Energy Technology Data Exchange (ETDEWEB)

    Valadares, Agnes Araujo; Woellner, Eduardo Bechtloff; Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto, E-mail: agnesvaladares@me.com [Universidade de Sao Paulo (HC/FMUSP), Sao Paulo, SP (Brazil). Fac. de Medicina. Hospital das Clinicas; Duarte, Paulo Schiavom; Coura-Filho, George Barberio [Instituto do Cancer do Estado de Sao Paulo Octavio Frias de Oliveira (ICESP), Sao Paulo, SP (Brazil)

    2015-01-15

    Objective: to analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on {sup 18}FNaF PET/CT scans. Materials and methods: a total of 254 {sup 18}F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses covered 675 regions classified as normal (236 RH, 232 RF, and 207 LV1). Results: mean SUV for each skeletal region was 3.8, 5.4 and 14.4 for RH, RF, and LV1, respectively. As the studies were grouped according to mAs value, the mean SUV values were 3.8, 3.9 and 3.7 for 10, 20 and 30 mAs, respectively, in the RH region; 5.4, 5.5 and 5.4 for 10, 20 and 30 mAs, respectively, in the RF region; 13.8, 14.9 and 14.5 for 10, 20 and 30 mAs, respectively, in the LV1 region. Conclusion: the three tube current values yielded similar results for SUV calculation. (author)

  18. Comparison of standardized uptake values measured on 18F-NaF PET/CT scans using three different tube current intensities

    International Nuclear Information System (INIS)

    Valadares, Agnes Araujo; Woellner, Eduardo Bechtloff; Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto

    2015-01-01

    Objective: to analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on 18 FNaF PET/CT scans. Materials and methods: a total of 254 18 F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses covered 675 regions classified as normal (236 RH, 232 RF, and 207 LV1). Results: mean SUV for each skeletal region was 3.8, 5.4 and 14.4 for RH, RF, and LV1, respectively. As the studies were grouped according to mAs value, the mean SUV values were 3.8, 3.9 and 3.7 for 10, 20 and 30 mAs, respectively, in the RH region; 5.4, 5.5 and 5.4 for 10, 20 and 30 mAs, respectively, in the RF region; 13.8, 14.9 and 14.5 for 10, 20 and 30 mAs, respectively, in the LV1 region. Conclusion: the three tube current values yielded similar results for SUV calculation. (author)

  19. Comparison of standardized uptake values measured on F-NaF PET/CT scans using three different tube current intensities.

    Science.gov (United States)

    Valadares, Agnes Araujo; Duarte, Paulo Schiavom; Woellner, Eduardo Bechtloff; Coura-Filho, George Barberio; Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto

    2015-01-01

    To analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on (18)FNaF PET/CT scans. A total of 254 (18)F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses covered 675 regions classified as normal (236 RH, 232 RF, and 207 LV1). Mean SUV for each skeletal region was 3.8, 5.4 and 14.4 for RH, RF, and LV1, respectively. As the studies were grouped according to mAs value, the mean SUV values were 3.8, 3.9 and 3.7 for 10, 20 and 30 mAs, respectively, in the RH region; 5.4, 5.5 and 5.4 for 10, 20 and 30 mAs, respectively, in the RF region; 13.8, 14.9 and 14.5 for 10, 20 and 30 mAs, respectively, in the LV1 region. The three tube current values yielded similar results for SUV calculation.

  20. Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch

    Energy Technology Data Exchange (ETDEWEB)

    May, Matthias S.; Kuettner, Axel; Lell, Michael M.; Wuest, Wolfgang; Scharf, Michael; Uder, Michael [University of Erlangen, Department of Radiology, Erlangen (Germany); Deak, Paul; Kalender, Willi A. [University of Erlangen, Department of Medical Physics, Erlangen (Germany); Keller, Andrea K.; Haeberle, Lothar [University of Erlangen, Department of Medical Informatics, Biometry and Epidemiology, Erlangen (Germany); Achenbach, Stephan; Seltmann, Martin [University of Erlangen, Department of Cardiology, Erlangen (Germany)

    2012-03-15

    To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. Estimates for mean relative ED was 7.1 {+-} 2.1 mSv/100 mAs for TCM and 12.5 {+-} 5.3 mSv/100 mAs for CTC (P < 0.001). Relative dose reduction at low HR ({<=}60 bpm) was highest (49 {+-} 5%) compared to intermediate (60-70 bpm, 33 {+-} 12%) and high HR (>70 bpm, 29 {+-} 12%). However lowest ED is achieved at high HR (5.2 {+-} 1.5 mSv/100 mAs), compared with intermediate (6.7 {+-} 1.6 mSv/100 mAs) and low (8.3 {+-} 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. circle Monte Carlo simulations allow for individual radiation dose calculations. (orig.)

  1. Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch

    International Nuclear Information System (INIS)

    May, Matthias S.; Kuettner, Axel; Lell, Michael M.; Wuest, Wolfgang; Scharf, Michael; Uder, Michael; Deak, Paul; Kalender, Willi A.; Keller, Andrea K.; Haeberle, Lothar; Achenbach, Stephan; Seltmann, Martin

    2012-01-01

    To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. Estimates for mean relative ED was 7.1 ± 2.1 mSv/100 mAs for TCM and 12.5 ± 5.3 mSv/100 mAs for CTC (P 70 bpm, 29 ± 12%). However lowest ED is achieved at high HR (5.2 ± 1.5 mSv/100 mAs), compared with intermediate (6.7 ± 1.6 mSv/100 mAs) and low (8.3 ± 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. circle Monte Carlo simulations allow for individual radiation dose calculations. (orig.)

  2. Automatic exposure control in CT: the effect of patient size, anatomical region and prescribed modulation strength on tube current and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Papadakis, Antonios E. [University Hospital of Heraklion, Department of Medical Physics, Stavrakia, P.O. Box 1352, Heraklion, Crete (Greece); Perisinakis, Kostas; Damilakis, John [University of Crete, Faculty of Medicine, Department of Medical Physics, P.O. Box 2208, Heraklion, Crete (Greece)

    2014-10-15

    To study the effect of patient size, body region and modulation strength on tube current and image quality on CT examinations that use automatic tube current modulation (ATCM). Ten physical anthropomorphic phantoms that simulate an individual as neonate, 1-, 5-, 10-year-old and adult at various body habitus were employed. CT acquisition of head, neck, thorax and abdomen/pelvis was performed with ATCM activated at weak, average and strong modulation strength. The mean modulated mAs (mAs{sub mod}) values were recorded. Image noise was measured at selected anatomical sites. The mAs{sub mod} recorded for neonate compared to 10-year-old increased by 30 %, 14 %, 6 % and 53 % for head, neck, thorax and abdomen/pelvis, respectively, (P < 0.05). The mAs{sub mod} was lower than the preselected mAs with the exception of the 10-year-old phantom. In paediatric and adult phantoms, the mAs{sub mod} ranged from 44 and 53 for weak to 117 and 93 for strong modulation strength, respectively. At the same exposure parameters image noise increased with body size (P < 0.05). The ATCM system studied here may affect dose differently for different patient habitus. Dose may decrease for overweight adults but increase for children older than 5 years old. Care should be taken when implementing ATCM protocols to ensure that image quality is maintained. circle ATCM efficiency is related to the size of the patient's body. (orig.)

  3. A new circuit technique for reduced leakage current in Deep Submicron CMOS technologies

    Directory of Open Access Journals (Sweden)

    A. Schmitz

    2005-01-01

    Full Text Available Modern CMOS processes in the Deep Submicron regime are restricted to supply voltages below 2 volts and further to account for the transistors' field strength limitations and to reduce the power per logic gate. To maintain the high switching performance, the threshold voltage must be scaled according with the supply voltage. However, this leads to an increased subthreshold current of the transistors in standby mode (VGS=0. Another source of leakage is gate current, which becomes significant for gate oxides of 3nm and below. We propose a Self-Biasing Virtual Rails (SBVR - CMOS technique which acts like an adaptive local supply voltage in case of standby mode. Most important sources of leakage currents are reduced by this technique. Moreover, SBVR-CMOS is capable of conserving stored information in sleep mode, which is vital for memory circuits. Memories are exposed to radiation causing soft errors. This well-known problem becomes even worse in standby mode of typical SRAMs, that have low driving performance to withstand alpha particle hits. In this paper, a 16-transistor SRAM cell is proposed, which combines the advantage of extremely low leakage currents with a very high soft error stability.

  4. Failure analysis of retired steam generator tubings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong Pyo; Kim, J. S.; Hwang, S. S. and others

    2005-04-15

    Degradation of steam generator leads to forced outage and extension of outage, which causes increase in repair cost, cost of purchasing replacement power and radiation exposure of workers. Steam generator tube rupture incident occurred in Uljin 4 in 2002, which made public sensitive to nuclear power plant. To keep nuclear energy as a main energy source, integrity of steam generator should be demonstrated. Quantitative relationship between ECT(eddy current test) signal and crack size is needed in assesment of integrity of steam generator in pressurized water reactor. However, it is not fully established for application in industry. Retired steam generator of Kori 1 has many kinds of crack such as circumferential and axial primary water stress corrosion crack and outer diameter stress corrosion crack(ODSCC). So, it can be used in qualifying and improving ECT technology and in condition monitoring assesment for crack detected in ISI(in service inspection). In addition, examination of pulled tube of Kori 1 retired steam generator will give information about effectiveness of non welded sleeving technology which was employed to repair defect tubes and remedial action which was applied to mitigate ODSCC. In this project, hardware such as semi hot lab. for pulled tube examination and modification transportation cask for pulled tube and software such as procedure of transportation of radioactive steam generator tube and non-destructive and destructive examination of pulled tube were established. Non-destructive and destructive examination of pulled tubes from Kori 1 retired steam generator were performed in semi hot lab. Remedial actions applied to Kori 1 retired steam generator, PWSCC trend and bulk water chemistry and crevice chemistry in Kori 1 were evaluated. Electrochemical decontamination technology for pulled tube was developed to reduce radiation exposure and enhance effectiveness of pulled tube examination. Multiparameter algorithm developed at ANL, USA was

  5. Tube plug

    International Nuclear Information System (INIS)

    Zafred, P. R.

    1985-01-01

    The tube plug comprises a one piece mechanical plug having one open end and one closed end which is capable of being inserted in a heat exchange tube and internally expanded into contact with the inside surface of the heat exchange tube for preventing flow of a coolant through the heat exchange tube. The tube plug also comprises a groove extending around the outside circumference thereof which has an elastomeric material disposed in the groove for enhancing the seal between the tube plug and the tube

  6. Gastrostomy Tube (G-Tube)

    Science.gov (United States)

    ... any of these problems: a dislodged tube a blocked or clogged tube any signs of infection (including redness, swelling, or warmth at the tube site; discharge that's yellow, green, or foul-smelling; fever) excessive bleeding or drainage from the tube site severe abdominal pain lasting ...

  7. Simulation of Working Processes in the Water-Tube Boiler Furnace with the Purpose of Reducing Emissions of Nitrogen Oxides

    Directory of Open Access Journals (Sweden)

    Redko A.A.

    2017-04-01

    Full Text Available A significant number of domestic and industrial boilers are in operation in Ukraine. Nitrogen oxides are the most dangerous among all combustion products that pollute the atmosphere, therefore, one should take some measures for decreasing the formation of nitrogen oxides during combustion. The studies were carried out at the boilers of low power (100 kW with a tubular radiator and an open end. The studies in the furnaces of industrial steam boilers having a tubular radiator with a closed end have not been done. The numerical study results of the gaseous fuel combustion processes in the furnace of a DE-10/14 steam water-tube boiler are presented. The fuel-air mixture is formed by premixing the 15% part of the air with a primary burner twist factor n=2.4 and a secondary burner twist factor n=1.6, and an air excess factor αв=10. As a result of the studies, the temperature and velocity distributions of gases in the combustion chamber, the density of heat flows on the screen tubular surfaces, and the concentrations of the combustion components were determined. Flue gas recirculation in the volume of 80-100% is provided, and the reversible movement of combustion products towards the combustion front provides a reduction in the concentration of nitrogen oxides up to 123-125 mg/m3 at the furnace outlet. Disadvantages are the following: the formation of stagnant zones near the end of the secondary radiator. The optimum diameter of the tubular radiator equals to two burners diameters and tubular radiator is located at a distance of one meter from the burner cutoff.

  8. Estimation of plasma ion saturation current and reduced tip arcing using Langmuir probe harmonics.

    Science.gov (United States)

    Boedo, J A; Rudakov, D L

    2017-03-01

    We present a method to calculate the ion saturation current, I sat , for Langmuir probes at high frequency (>100 kHz) using the harmonics technique and we compare that to a direct measurement of I sat . It is noted that the I sat estimation can be made directly by the ratio of harmonic amplitudes, without explicitly calculating T e . We also demonstrate that since the probe tips using the harmonic method are oscillating near the floating potential, drawing little power, this method reduces tip heating and arcing and allows plasma density measurements at a plasma power flux that would cause continuously biased tips to arc. A multi-probe array is used, with two spatially separated tips employing the harmonics technique and measuring the amplitude of at least two harmonics per tip. A third tip, located between the other two, measures the ion saturation current directly. We compare the measured and calculated ion saturation currents for a variety of plasma conditions and demonstrate the validity of the technique and its use in reducing arcs.

  9. An overview of the Hadoop/MapReduce/HBase framework and its current applications in bioinformatics

    International Nuclear Information System (INIS)

    Taylor, Ronald C.

    2010-01-01

    Bioinformatics researchers are increasingly confronted with analysis of ultra large-scale data sets, a problem that will only increase at an alarming rate in coming years. Recent developments in open source software, that is, the Hadoop project and associated software, provide a foundation for scaling to petabyte scale data warehouses on Linux clusters, providing fault-tolerant parallelized analysis on such data using a programming style named MapReduce. An overview is given of the current usage within the bioinformatics community of Hadoop, a top-level Apache Software Foundation project, and of associated open source software projects. The concepts behind Hadoop and the associated HBase project are defined, and current bioinformatics software that employ Hadoop is described. The focus is on next-generation sequencing, as the leading application area to date.

  10. Modifications in agricultural and animal breeding current operations to reduce the contamination of food chains

    International Nuclear Information System (INIS)

    Maubert, Henry; Renard, Philippe

    1997-01-01

    After a nuclear accident it is compulsory to reduce as much as possible the population exposure to radioactive aerosols deposed upon soils and different surfaces. The radio-agronomic countermeasures are protection directives applicable to the agricultural system and agro-alimentary chain which enable to implement this commandment. Their intrinsic and cumulated efficiency, the conditions and preoccupations of implementation are now better recognized especially now by their large scale application after the Chernobyl accident. As modifications in the current agricultural operation two procedures are mentioned: the rehabilitation techniques and the utilization of adjuvants. Concerning modifications in the current animal breeding methodology in the specific conditions of animal production and restricted pasturage there are discussed methods of diminishing the metabolic transfer to milk and meat and removing radioactivity by proper and simpler agro-alimentary processing and culinary preparations

  11. Current pulse: can a production system reduce medical errors in health care?

    Science.gov (United States)

    Printezis, Antonios; Gopalakrishnan, Mohan

    2007-01-01

    One of the reasons for rising health care costs is medical errors, a majority of which result from faulty systems and processes. Health care in the past has used process-based initiatives such as Total Quality Management, Continuous Quality Improvement, and Six Sigma to reduce errors. These initiatives to redesign health care, reduce errors, and improve overall efficiency and customer satisfaction have had moderate success. Current trend is to apply the successful Toyota Production System (TPS) to health care since its organizing principles have led to tremendous improvement in productivity and quality for Toyota and other businesses that have adapted them. This article presents insights on the effectiveness of TPS principles in health care and the challenges that lie ahead in successfully integrating this approach with other quality initiatives.

  12. Reducing radiation dose in the diagnosis of pulmonary embolism using adaptive statistical iterative reconstruction and lower tube potential in computed tomography

    International Nuclear Information System (INIS)

    Kaul, David; Grupp, Ulrich; Kahn, Johannes; Wiener, Edzard; Hamm, Bernd; Streitparth, Florian; Ghadjar, Pirus

    2014-01-01

    To assess the impact of ASIR (adaptive statistical iterative reconstruction) and lower tube potential on dose reduction and image quality in chest computed tomography angiographies (CTAs) of patients with pulmonary embolism. CT data from 44 patients with pulmonary embolism were acquired using different protocols - Group A: 120 kV, filtered back projection, n = 12; Group B: 120 kV, 40 % ASIR, n = 12; Group C: 100 kV, 40 % ASIR, n = 12 and Group D: 80 kV, 40 % ASIR, n = 8. Normalised effective dose was calculated; image quality was assessed quantitatively and qualitatively. Normalised effective dose in Group B was 33.8 % lower than in Group A (p = 0.014) and 54.4 % lower in Group C than in Group A (p < 0.001). Group A, B and C did not show significant differences in qualitative or quantitative analysis of image quality. Group D showed significantly higher noise levels in qualitative and quantitative analysis, significantly more artefacts and decreased overall diagnosability. Best results, considering dose reduction and image quality, were achieved in Group C. The combination of ASIR and lower tube potential is an option to reduce radiation without significant worsening of image quality in the diagnosis of pulmonary embolism. (orig.)

  13. Reducing radiation dose in the diagnosis of pulmonary embolism using adaptive statistical iterative reconstruction and lower tube potential in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kaul, David [Campus Virchow-Klinikum, Department of Radiation Oncology, Charite School of Medicine and University Hospital, Berlin (Germany); Charite School of Medicine and University Hospital, Department of Radiology, Berlin (Germany); Grupp, Ulrich; Kahn, Johannes; Wiener, Edzard; Hamm, Bernd; Streitparth, Florian [Charite School of Medicine and University Hospital, Department of Radiology, Berlin (Germany); Ghadjar, Pirus [Campus Virchow-Klinikum, Department of Radiation Oncology, Charite School of Medicine and University Hospital, Berlin (Germany)

    2014-11-15

    To assess the impact of ASIR (adaptive statistical iterative reconstruction) and lower tube potential on dose reduction and image quality in chest computed tomography angiographies (CTAs) of patients with pulmonary embolism. CT data from 44 patients with pulmonary embolism were acquired using different protocols - Group A: 120 kV, filtered back projection, n = 12; Group B: 120 kV, 40 % ASIR, n = 12; Group C: 100 kV, 40 % ASIR, n = 12 and Group D: 80 kV, 40 % ASIR, n = 8. Normalised effective dose was calculated; image quality was assessed quantitatively and qualitatively. Normalised effective dose in Group B was 33.8 % lower than in Group A (p = 0.014) and 54.4 % lower in Group C than in Group A (p < 0.001). Group A, B and C did not show significant differences in qualitative or quantitative analysis of image quality. Group D showed significantly higher noise levels in qualitative and quantitative analysis, significantly more artefacts and decreased overall diagnosability. Best results, considering dose reduction and image quality, were achieved in Group C. The combination of ASIR and lower tube potential is an option to reduce radiation without significant worsening of image quality in the diagnosis of pulmonary embolism. (orig.)

  14. SU-G-JeP4-13: Continuous Intra-Fractional Monitoring of the Prostate Using Dynamic KV Collimation and Tube Current Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, D [Dalhousie Unviersity, Halifax, Nova Scotia (Canada); Robar, J [Dalhousie Unviersity, Halifax, Nova Scotia (Canada); Nova Scotia Health Authority, Halifax, NS (Canada)

    2016-06-15

    Purpose: The focus of this work is to improve the available kV image quality for continuous intra-fraction monitoring of the prostate. This is investigated using a novel blade collimation system enabling modulated volume-of-interest (VOI) imaging of prostate fiducial markers. Methods: A four-blade dynamic kV collimator was used to track a VOI during gantry rotation. Planar image quality was investigated as a function of collimator dimension, while maintaining the same dose to isocenter, for a 22.2 cm diameter cylindrical water phantom with a 9 mm diameter bone insert. A sample prostate anatomy was defined in the planning system, including three fiducial markers within the CTV. The VOI margin around each marker was set to be 2σ of the population covariance matrix characterizing prostate motion. DRRs were used to calculate the kV attenuation for each VOI as a function of angle. The optimal marker and tube current were determined using kV attenuation. Monte Carlo simulations were used to calculate the imaging dose to the phantom and MV scatter dose to the imaging panel. Results: Preliminary measurements show an increase in CNR by a factor of 1.3 with the VOI method, when decreasing from an 6×6 to 2×2 cm{sup 2} field. Attenuation calculations show a change in kV fluence at the detector by a factor of 21.6 with fiducial optimization; resultant tube current modulation increases maximum dose by a factor of 1.4 compared to no modulation. MV scatter contribution to the kV detector changes by approximately a factor of two over a complete gantry rotation. Conclusion: The dynamic collimation system allows single fiducial marker tracking at a very low dose, with reduction of scatter and improvement of image quality, compared to imaging the entire prostate. The approach is compatible with tube current modulation, which enables consistent image quality throughout the range of gantry rotation. This project was funded by Varian Medical Systems.

  15. Simple engineering design for complex thermoelectric generators based on reduced current approach

    DEFF Research Database (Denmark)

    Wijesooriyage, Waruna Dissanayaka; Rezaniakolaei, Alireza; Rosendahl, Lasse

    2015-01-01

    Thermoelectric generators (TEGs) are niche candidate for the field of energy management as electrical generator devices. Generally, comprehensive and accurate design techniques for TEGs (thermoelectric generators), such as reduced current approach (RCA), are complex and time consuming processes....... This study develops a simple, comprehensive and accurate TEG designing technique based on RCA. The proposed method can predict the most efficient TEG architecture with more than 97% accuracy comparing to the RCA over wide range of possible temperature and zT for present TEG applications. Moreover...

  16. Reduce the start current of Smith-Purcell backward wave oscillator by sidewall grating

    International Nuclear Information System (INIS)

    Li, D.; Imasaki, K.; Gao, X.; Yang, Z.; Park, Gun-Sik

    2007-01-01

    A sidewall grating for the Smith-Purcell device is proposed to enhance the coupling of the optical mode with the electron beam and, consequently, relax the stringent requirements to the electron beam. With the help of three-dimensional particle-in-cell simulations, it has been shown that, comparing with the general grating, the usage of a sidewall grating improves the growth rate and dramatically shortens the time for the device to reach saturation. It is also found that the sidewall grating holds the potential to reduce the start current for the operation of a Smith-Purcell backward wave oscillator

  17. Support of the 'fallopian tube hypothesis' in a prospective series of risk-reducing salpingo-oophorectomy specimens

    NARCIS (Netherlands)

    Reitsma, Welmoed; de Bock, Geertruida H.; Oosterwijk, Jan C.; Bart, Joost; Hollema, Harry; Mourits, Marian J. E.

    Objective: To determine the prevalence, localisation and type of occult (non) invasive cancer in risk-reducing salpingo-oophorectomy (RRSO) specimens in BRCA-mutation carriers and high-risk women from BRCA-negative families. Methods: A consecutive series of RRSO specimens of asymptomatic,

  18. Comment on 'Relation between space charge limited current and power loss in open drift tubes' [Phys. Plasmas 13, 073101 (2006)

    International Nuclear Information System (INIS)

    Swanekamp, S. B.; Schumer, J. W.

    2007-01-01

    In Phys Plasmas 13, 073101 (2006), the drop in the space-charge-limited (SCL) current for a beam injected into a space with an open boundary is analyzed with an electromagnetic particle-in-cell code. The authors explained the power loss observed at the open boundary as the loss of electromagnetic radiation created from the deceleration of electrons in the gap, and they developed an effective voltage theory to predict the drop in the SCL current observed in the simulations. In this Comment, we show that, provided the current remains below the SCL value, the electric and magnetic fields are constant in time so that power loss from the open boundary is a dc phenomenon with no rf power leaving through the boundary. We show that the electric and magnetic fields are static in time and static fields DO NOT RADIATE. Instead, the electron beam charges the collector plate, which causes a real electrostatic electric field to develop. The electron energy loss is not due to radiation but rather to the work done by this electrostatic field on the electrons as they move across the gap. This is precisely the energy dissipated in the matched resistance across the open boundary, which is a consequence of the boundary condition. Furthermore, since a real electrostatic potential develops, the voltage drop is real and there is no need to call the voltage drop an effective voltage

  19. TU-F-CAMPUS-I-04: A Novel Phantom to Evaluate Longitudinal and Angular Automatic Tube Current Modulation (ATCM) in CT

    Energy Technology Data Exchange (ETDEWEB)

    Merzan, D; Bujila, R; Nowik, P [Dept. of Medical Physics, Karolinska University Hospital, Stockholm (Sweden)

    2015-06-15

    Purpose: To manufacture a phantom specifically designed for the purpose of evaluating the performance of the longitudinal and angular automatic tube current modulation (ATCM) on modern CT scanners. Methods: In order to evaluate angular ATCM, the phantom has an elliptical cross section (aspect ratio 3:2). To evaluate longitudinal ATCM, the phantom consists of 3 sections, with different major axes (25 cm, 30 cm and 35 cm). Each section is 15 cm long in the longitudinal direction. Between each section is a smooth transition. The phantom was milled from a solid block of PMMA. ATCM performance is evaluated by 1) analyzing the applied tube current for each slice of the phantom and 2) analyzing the distribution of image noise (σ) along the scan direction at different positions in the phantom. A demonstration of the ATCM performance evaluation is given by investigating the effects of miscentering during a CT scan. Results: The developed phantom has proven useful for evaluating both the longitudinal and angular ATCM on modern CT scanners (spiral collimations ≥ 4 cm). Further benefits are the smooth transitions between the sections that prevent abnormal responses in the ATCM and the invariant sections that provide a means for investigating the stability of image noise. The homogeneity of the phantom makes image noise at different positions along the scan direction easy to quantify, which is crucial to understand how well the applied ATCM can produce a desired image quality. Conclusion: It is important to understand how the ATCM functions on CT scanners as it can directly affect dose and image quality. The phantom that has been developed is a most valuable tool to understand how different variables during a scan can affect the outcome of the longitudinal and angular ATCM.

  20. TU-F-CAMPUS-I-04: A Novel Phantom to Evaluate Longitudinal and Angular Automatic Tube Current Modulation (ATCM) in CT

    International Nuclear Information System (INIS)

    Merzan, D; Bujila, R; Nowik, P

    2015-01-01

    Purpose: To manufacture a phantom specifically designed for the purpose of evaluating the performance of the longitudinal and angular automatic tube current modulation (ATCM) on modern CT scanners. Methods: In order to evaluate angular ATCM, the phantom has an elliptical cross section (aspect ratio 3:2). To evaluate longitudinal ATCM, the phantom consists of 3 sections, with different major axes (25 cm, 30 cm and 35 cm). Each section is 15 cm long in the longitudinal direction. Between each section is a smooth transition. The phantom was milled from a solid block of PMMA. ATCM performance is evaluated by 1) analyzing the applied tube current for each slice of the phantom and 2) analyzing the distribution of image noise (σ) along the scan direction at different positions in the phantom. A demonstration of the ATCM performance evaluation is given by investigating the effects of miscentering during a CT scan. Results: The developed phantom has proven useful for evaluating both the longitudinal and angular ATCM on modern CT scanners (spiral collimations ≥ 4 cm). Further benefits are the smooth transitions between the sections that prevent abnormal responses in the ATCM and the invariant sections that provide a means for investigating the stability of image noise. The homogeneity of the phantom makes image noise at different positions along the scan direction easy to quantify, which is crucial to understand how well the applied ATCM can produce a desired image quality. Conclusion: It is important to understand how the ATCM functions on CT scanners as it can directly affect dose and image quality. The phantom that has been developed is a most valuable tool to understand how different variables during a scan can affect the outcome of the longitudinal and angular ATCM

  1. TU-H-207A-08: Estimating Radiation Dose From Low-Dose Lung Cancer Screening CT Exams Using Tube Current Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, A; Bostani, M [University of California, Los Angeles, Los Angeles, CA (United States); McMillan, K [Mayo Clinic, Rochester, MN (United States); Zankl, M [Helmholtz Zentrum Munchen, Neuherberg (Germany); Cagnon, C [UCLA Medical Center, Los Angeles, CA (United States); McNitt-Gray, M [UCLA School of Medicine, Los Angeles, CA (United States)

    2016-06-15

    Purpose: The purpose of this work is to estimate effective and lung doses from a low-dose lung cancer screening CT protocol using Tube Current Modulation (TCM) across patient models of different sizes. Methods: Monte Carlo simulation methods were used to estimate effective and lung doses from a low-dose lung cancer screening protocol for a 64-slice CT (Sensation 64, Siemens Healthcare) that used TCM. Scanning parameters were from the AAPM protocols. Ten GSF voxelized patient models were used and had all radiosensitive organs identified to facilitate estimating both organ and effective doses. Predicted TCM schemes for each patient model were generated using a validated method wherein tissue attenuation characteristics and scanner limitations were used to determine the TCM output as a function of table position and source angle. The water equivalent diameter (WED) was determined by estimating the attenuation at the center of the scan volume for each patient model. Monte Carlo simulations were performed using the unique TCM scheme for each patient model. Lung doses were tallied and effective doses were estimated using ICRP 103 tissue weighting factors. Effective and lung dose values were normalized by scanspecific 32 cm CTDIvol values based upon the average tube current across the entire simulated scan. Absolute and normalized doses were reported as a function of WED for each patient. Results: For all ten patients modeled, the effective dose using TCM protocols was below 1.5 mSv. Smaller sized patient models experienced lower absolute doses compared to larger sized patients. Normalized effective and lung doses showed some dependence on patient size (R2 = 0.77 and 0.78, respectively). Conclusion: Effective doses for a low-dose lung screening protocol using TCM were below 1.5 mSv for all patient models used in this study. Institutional research agreement, Siemens Healthcare; Past recipient, research grant support, Siemens Healthcare; Consultant, Toshiba America Medical

  2. TU-H-207A-08: Estimating Radiation Dose From Low-Dose Lung Cancer Screening CT Exams Using Tube Current Modulation

    International Nuclear Information System (INIS)

    Hardy, A; Bostani, M; McMillan, K; Zankl, M; Cagnon, C; McNitt-Gray, M

    2016-01-01

    Purpose: The purpose of this work is to estimate effective and lung doses from a low-dose lung cancer screening CT protocol using Tube Current Modulation (TCM) across patient models of different sizes. Methods: Monte Carlo simulation methods were used to estimate effective and lung doses from a low-dose lung cancer screening protocol for a 64-slice CT (Sensation 64, Siemens Healthcare) that used TCM. Scanning parameters were from the AAPM protocols. Ten GSF voxelized patient models were used and had all radiosensitive organs identified to facilitate estimating both organ and effective doses. Predicted TCM schemes for each patient model were generated using a validated method wherein tissue attenuation characteristics and scanner limitations were used to determine the TCM output as a function of table position and source angle. The water equivalent diameter (WED) was determined by estimating the attenuation at the center of the scan volume for each patient model. Monte Carlo simulations were performed using the unique TCM scheme for each patient model. Lung doses were tallied and effective doses were estimated using ICRP 103 tissue weighting factors. Effective and lung dose values were normalized by scanspecific 32 cm CTDIvol values based upon the average tube current across the entire simulated scan. Absolute and normalized doses were reported as a function of WED for each patient. Results: For all ten patients modeled, the effective dose using TCM protocols was below 1.5 mSv. Smaller sized patient models experienced lower absolute doses compared to larger sized patients. Normalized effective and lung doses showed some dependence on patient size (R2 = 0.77 and 0.78, respectively). Conclusion: Effective doses for a low-dose lung screening protocol using TCM were below 1.5 mSv for all patient models used in this study. Institutional research agreement, Siemens Healthcare; Past recipient, research grant support, Siemens Healthcare; Consultant, Toshiba America Medical

  3. Automatic exposure control in CT: the effect of patient size, anatomical region and prescribed modulation strength on tube current and image quality.

    Science.gov (United States)

    Papadakis, Antonios E; Perisinakis, Kostas; Damilakis, John

    2014-10-01

    To study the effect of patient size, body region and modulation strength on tube current and image quality on CT examinations that use automatic tube current modulation (ATCM). Ten physical anthropomorphic phantoms that simulate an individual as neonate, 1-, 5-, 10-year-old and adult at various body habitus were employed. CT acquisition of head, neck, thorax and abdomen/pelvis was performed with ATCM activated at weak, average and strong modulation strength. The mean modulated mAs (mAsmod) values were recorded. Image noise was measured at selected anatomical sites. The mAsmod recorded for neonate compared to 10-year-old increased by 30 %, 14 %, 6 % and 53 % for head, neck, thorax and abdomen/pelvis, respectively, (P < 0.05). The mAsmod was lower than the preselected mAs with the exception of the 10-year-old phantom. In paediatric and adult phantoms, the mAsmod ranged from 44 and 53 for weak to 117 and 93 for strong modulation strength, respectively. At the same exposure parameters image noise increased with body size (P < 0.05). The ATCM system studied here may affect dose differently for different patient habitus. Dose may decrease for overweight adults but increase for children older than 5 years old. Care should be taken when implementing ATCM protocols to ensure that image quality is maintained. • ATCM efficiency is related to the size of the patient's body. • ATCM should be activated without caution in overweight adult individuals. • ATCM may increase radiation dose in children older than 5 years old. • ATCM efficiency depends on the protocol selected for a specific anatomical region. • Modulation strength may be appropriately tuned to enhance ATCM efficiency.

  4. The current state of the Russian reduced enrichment research reactors program

    Energy Technology Data Exchange (ETDEWEB)

    Aden, V.G.; Kartashov, E.F.; Lukichev, V.A. [and others

    1997-08-01

    During the last year after the 16-th International Conference on Reducing Fuel Enrichment in Research Reactors held in October, 1993 in Oarai, Japan, the conclusive stage of the Program on reducing fuel enrichment (to 20% in U-235) in research reactors was finally made up in Russia. The Program was started late in 70th and the first stage of the Program was completed by 1986 which allowed to reduce fuel enrichment from 80-90% to 36%. The completion of the Program current stage, which is counted for 5-6 years, will exclude the use of the fuel enriched by more than 20% from RF to other countries such as: Poland, Czeck Republick, Hungary, Roumania, Bulgaria, Libya, Viet-Nam, North Korea, Egypt, Latvia, Ukraine, Uzbekistan and Kazakhstan. In 1994 the Program, approved by RF Minatom authorities, has received the status of an inter-branch program since it was admitted by the RF Ministry for Science and Technical Policy. The Head of RF Minatom central administrative division N.I.Ermakov was nominated as the Head of the Russian Program, V.G.Aden, RDIPE Deputy Director, was nominated as the scientific leader. The Program was submitted to the Commission for Scientific, Technical and Economical Cooperation between USA and Russia headed by Vice-President A. Gore and Prime Minister V. Chemomyrdin and was given support also.

  5. Anodal transcranial direct current stimulation reduces psychophysically measured surround suppression in the human visual cortex.

    Directory of Open Access Journals (Sweden)

    Daniel P Spiegel

    Full Text Available Transcranial direct current stimulation (tDCS is a safe, non-invasive technique for transiently modulating the balance of excitation and inhibition within the human brain. It has been reported that anodal tDCS can reduce both GABA mediated inhibition and GABA concentration within the human motor cortex. As GABA mediated inhibition is thought to be a key modulator of plasticity within the adult brain, these findings have broad implications for the future use of tDCS. It is important, therefore, to establish whether tDCS can exert similar effects within non-motor brain areas. The aim of this study was to assess whether anodal tDCS could reduce inhibitory interactions within the human visual cortex. Psychophysical measures of surround suppression were used as an index of inhibition within V1. Overlay suppression, which is thought to originate within the lateral geniculate nucleus (LGN, was also measured as a control. Anodal stimulation of the occipital poles significantly reduced psychophysical surround suppression, but had no effect on overlay suppression. This effect was specific to anodal stimulation as cathodal stimulation had no effect on either measure. These psychophysical results provide the first evidence for tDCS-induced reductions of intracortical inhibition within the human visual cortex.

  6. Computed tomography: influence of varying tube current on patient dose and correctness of effective dose calculations; Computertomografie: Einfluss des variablen Roehrenstroms auf die Patientendosis und die Genauigkeit von Berechnungen der effektiven Dosis

    Energy Technology Data Exchange (ETDEWEB)

    Hietschold, V. [Inst. und Poliklinik fuer Radiologische Diagnostik, Universitaetsklinikum Carl-Gustav-Carus der TU Dresden (Germany); Koch, A.; Laniado, M.; Abolmaali, N.D. [OncoRay, Molecular Imaging, TU Dresden (Germany)

    2008-05-15

    Purpose: determination of the influence of tube currents varying during a CT scan on organ doses and on the effective dose as a function of patient constitution. Evaluation of the accuracy of effective dose calculations based on summarizing parameters (effective mAs, dose length product [DLP]) compared to calculations based on slice-specific tube currents. Materials and methods: investigation of the CT datasets of 806 patients acquired from the skull base to the proximal thigh with respect to the body mass index (BMI). The effective dose was calculated by means of slice-specific as well as region-specific conversion factors. Results: dose optimization by means of variable tube current resulted in a reduction of the gonad dose in patients with BMI {<=} 20.. 21 kg/m{sup 2} and of the effective dose in patients with BMI {<=} 26 kg/m{sup 2}. Effective dose values calculated with the DLP for 90% of the patients are within an interval of {+-} 20% of the values calculated using slice-specific tube currents. Conclusion: if tube current optimization during the CT scan was applied, for the scan region under investigation, at a BMI already below the German mean value, an increased effective dose was observed. Calculations of the effective dose on the basis of summarizing values such as DLP or effective mAs are of sufficient accuracy. (orig.)

  7. Circular electrodes to reduce the current variation of OTFTs with the drop-casted semiconducting layer

    Science.gov (United States)

    Dipu Kabir, H. M.; Ahmed, Zubair; Kariyadan, Remashan; Zhang, Lining; Chan, Mansun

    2018-06-01

    Circular organic thin film transistor (OTFT) structures are proposed to reduce the impact of variable grain alignment on the drive current of the polycrystalline organic thin film transistor (OTFT). As the circular structure is planar symmetric, the orientation of the grain cannot affect the drive current of the circular OTFT. Thus, circular electrodes expected to provide a lower variation. Top-gate, bottom-contact circular and conventional OTFTs with drop-casted polycrystalline 6,13-Bis(triisopropyl-silylethynyl) (TIPS)-Pentacene organic semiconducting layer (OSC) are fabricated to verify the theoretical variation reduction. The relative standard deviation (RSD), defined as the ratio of standard deviation and the average of drive current is used as the degree of variations in different structures. According to our fabrication result, circular transistors have a significantly lower variation (20% RSD), compared to the variation of conventional OTFTs (61% RSD). His research interests include Organic Electronics, VLSI Design, Embedded System, Neural Networks, and Solid-state devices. Between July 2001 and December 2002, he was a Visiting Professor at University of California at Berkeley and the Co-director of the BSIM program. He is currently still consulting on the development of the next generation compact models. He has been actively contributing to the professional community and hold many positions. He was a Board of Governor, Chair of the Education Committee, the Chair of the Region 10 subcommittee and a Distinguished lecturer of the IEEE Electron Device Society. He has also chaired many international conferences and acting as editors for a number of technical journals. In addition, he has received many awards including the UC Regents Fellowship, Golden Keys Scholarship for Academic Excellence, SRC Inventor Recognition Award, Rockwell Research Fellowship, R&D 100 award (for the BSIM3v3 project), Distinguished Teaching Award, the Shenzhen Science and Technology

  8. Inspection and repair of steam generator tubing with a robot

    International Nuclear Information System (INIS)

    Boehm, H.H.; Foerch, H.

    1985-01-01

    During inspection and repair of steam generator tubing, radiation exposure to personnel is an unrequested endowment. To combat this intrinsic handicap, a robot has been designed for deployment in all operations inside the steam generator water chamber. This measure drastically reduces entering time and also improves inspection capabilities with regard to the accuracy and reproduction of the desired tube address. The inherent flexibility of the robot allows for performing various inspection and repair techniques: eddy-current testing of tubing; ultrasonic testing of tubing; visual examination of tube ends; profilometry measurements; tube plugging; plug removal; tube extraction; sleeving of tubes; tube end repair; chemical cleaning; and thermal treatment. Plant experience has highlighted the following features of the robot: 1) short installation and demounting periods; 2) installation independent of manhole location; 3) installation possible from outside the steam generator; 4) only one relocation required to address all the tube positions; 5) fast and highly accurate positioning; 6) operational surveillance not required; and 7) drastic reduction of radiation exposure to personnel during repair work

  9. Synthesis of Pt nanoparticles on electrochemically reduced graphene oxide by potentiostatic and alternate current methods

    Energy Technology Data Exchange (ETDEWEB)

    Molina, J.; Fernández, J.; Río, A.I. del; Bonastre, J.; Cases, F., E-mail: fjcases@txp.upv.es

    2014-03-01

    Reduced graphene oxide (RGO) has been synthesized on Pt wires by means of a potentiodynamic method between + 0.6 V and − 1.4 V for 20 scans. Cyclic voltammetry characterization of the coatings showed the typical capacitative behavior of graphene. Pt nanoparticles were synthesized on Pt–RGO electrodes by means of potentiostatic methods and a comparison between different synthesis potentials (− 0.16, 0, + 0.2 and + 0.4 V) for the same synthesis charge (mC·cm{sup −2}) was established. The electrodes obtained were characterized in 0.5 M H{sub 2}SO{sub 4} solution to observe the characteristic oxidation and reduction processes of the Pt surface. A 0.5 M H{sub 2}SO{sub 4}/0.5 M CH{sub 3}OH solution was used to measure the catalytic properties of the deposits against methanol oxidation. The most appropriate potential to perform the synthesis was 0 V followed by − 0.16 V and + 0.2 V. The morphology of the coatings varied depending on the potential applied as observed by scanning electron microscopy. Alternate current methods were also used to synthesize Pt nanoparticles and compare the results with the traditional potentiostatic method. Different frequencies were used: 0.1, 1, 10, 100, 1000 and 10 000 Hz. Alternate current synthesis is more efficient than traditional potentiostatic methods, obtaining more electroactive coatings with less effective synthesis time. - Highlights: • Reduced graphene oxide has been obtained by electrochemical reduction on Pt wires. • Pt nanoparticles have been obtained potentiostatically at different potentials. • Pt nanoparticles have been obtained by ac methods with different frequencies. • ac synthesis is a better synthesis method than potentiostatic synthesis.

  10. Synthesis of Pt nanoparticles on electrochemically reduced graphene oxide by potentiostatic and alternate current methods

    International Nuclear Information System (INIS)

    Molina, J.; Fernández, J.; Río, A.I. del; Bonastre, J.; Cases, F.

    2014-01-01

    Reduced graphene oxide (RGO) has been synthesized on Pt wires by means of a potentiodynamic method between + 0.6 V and − 1.4 V for 20 scans. Cyclic voltammetry characterization of the coatings showed the typical capacitative behavior of graphene. Pt nanoparticles were synthesized on Pt–RGO electrodes by means of potentiostatic methods and a comparison between different synthesis potentials (− 0.16, 0, + 0.2 and + 0.4 V) for the same synthesis charge (mC·cm −2 ) was established. The electrodes obtained were characterized in 0.5 M H 2 SO 4 solution to observe the characteristic oxidation and reduction processes of the Pt surface. A 0.5 M H 2 SO 4 /0.5 M CH 3 OH solution was used to measure the catalytic properties of the deposits against methanol oxidation. The most appropriate potential to perform the synthesis was 0 V followed by − 0.16 V and + 0.2 V. The morphology of the coatings varied depending on the potential applied as observed by scanning electron microscopy. Alternate current methods were also used to synthesize Pt nanoparticles and compare the results with the traditional potentiostatic method. Different frequencies were used: 0.1, 1, 10, 100, 1000 and 10 000 Hz. Alternate current synthesis is more efficient than traditional potentiostatic methods, obtaining more electroactive coatings with less effective synthesis time. - Highlights: • Reduced graphene oxide has been obtained by electrochemical reduction on Pt wires. • Pt nanoparticles have been obtained potentiostatically at different potentials. • Pt nanoparticles have been obtained by ac methods with different frequencies. • ac synthesis is a better synthesis method than potentiostatic synthesis

  11. Large step-down DC-DC converters with reduced current stress

    International Nuclear Information System (INIS)

    Ismail, Esam H.

    2009-01-01

    In this paper, several DC-DC converters with large voltage step-down ratios are introduced. A simple modification in the output section of the conventional buck and quadratic converters can effectively extend the duty-cycle range. Only two additional components (an inductor and diode) are necessary for extending the duty-cycle range. The topologies presented in this paper show an improvement in the duty-cycle (about 40%) over the conventional buck and quadratic converters. Consequently, they are well suited for extreme step-down voltage conversion ratio applications. With extended duty-cycle, the current stress on all components is reduced, leading to a significant improvement of the system losses. The principle of operation, theoretical analysis, and comparison of circuit performances with other step-down converters is discussed regarding voltage and current stress. Experimental results of one prototype rated 40-W and operating at 100 kHz are provided in this paper to verify the performance of this new family of converters. The efficiency of the proposed converters is higher than the quadratic converters

  12. Application of low-tube current with iterative model reconstruction on Philips Brilliance iCT Elite FHD in the accuracy of spinal QCT using a European spine phantom.

    Science.gov (United States)

    Wu, Yan; Jiang, Yaojun; Han, Xueli; Wang, Mingyue; Gao, Jianbo

    2018-02-01

    To investigate the repeatability and accuracy of quantitative CT (QCT) measurement of bone mineral density (BMD) by low-mAs using iterative model reconstruction (IMR) technique based on phantom model. European spine phantom (ESP) was selected and measured on the Philips Brilliance iCT Elite FHD machine for 10 times. Data were transmitted to the QCT PRO workstation to measure BMD (mg/cm 3 ) of the ESP (L1, L2, L3). Scanning method: the voltage of X-ray tube is 120 kV, the electric current of X-ray tube output in five respective groups A-E were: 20, 30, 40, 50 and 60 mAs. Reconstruction: all data were reconstructed using filtered back projection (FBP), IR levels of hybrid iterative reconstruction (iDose 4 , levels 1, 2, 3, 4, 5, 6 were used) and IMR (levels 1, 2, 3 were used). ROIs were placed in the middle of L1, L2 and L3 spine phantom in each group. CT values, noise and contrast-to-noise ratio (CNR) were measured and calculated. One-way analysis of variance (ANOVA) was used to compare BMD values of different mAs and different IMR. Radiation dose [volume CT dose index (CTDI vol ) and dose length product (DLP)] was positively correlated with tube current. In L1 with low BMD, different mAs in FBP showed P0.05, indicating no difference in BMD. And P>0.05 was observed among BMD of spine phantom in L1, L2 and L3 under same mAs joined with varied iterative reconstruction. The BMD in L1 varied greatly during FBP reconstruction, and less variation was observed in reconstruction of IMR [1] and IMR [2]. The BMD of L2 changed more during FBP reconstruction, where less was observed in IMR [2]. The BMD of L3 varied greatly during FBP reconstruction, and was less varied in all levels of iDose 4 and reconstruction of IMR [2]. In addition, along with continuous mAs incensement, the CNRs in various algorithms continued to increase. Among them, CNR with the FBP algorithm is the lowest, and CNR of the IMR [3] algorithm is the highest. Repeated measurements of BMD with QCT in the ESP

  13. Evaluation of a High Concentrated Contrast Media Injection Protocol in Combination with Low Tube Current for Dose Reduction in Coronary Computed Tomography Angiography: A Randomized, Two-center Prospective Study.

    Science.gov (United States)

    Sun, Yibo; Hua, Yanqing; Wang, Mingpeng; Mao, Dingbiao; Jin, Xiu; Li, Cheng; Shi, Kailei; Xu, Jianrong

    2017-12-01

    The study aimed to prospectively evaluate the radiation dose reduction potential and image quality (IQ) of a high-concentration contrast media (HCCM) injection protocol in combination with a low tube current (mAs) in coronary computed tomography angiography. Eighty-one consecutive patients (mean age: 62 years; 34 females; body mass index: 18-31) were included and randomized-assigned into two groups. All computed tomography (CT) examinations were performed in two groups with the same tube voltage (100 kV), flow rate of contrast medium (5.0 mL/s), and iodine dose (22.8 g). An automatic mAs and low concentration contrast medium (300 mgI/mL) were used in group A, whereas effective mAs was reduced by a factor 0.6 along with HCCM (400 mgI/mL) in group B. Radiation dose was assessed (CT dose index [CTDI vol ] and dose length product), and vessel-based objective IQ for various regions of interest (enhancement, noise, signal-to-noise ratio, and contrast-to-noise ratio), subjective IQ, noise, and motion artifacts were analyzed overall and vessel-based with a 5-point Likert scale. The CT attenuation of coronary arteries and image noise in group B were significantly higher than those in group A (ranges: 507.5-548.1 Hounsfield units vs 407.5-444.5 Hounsfield units; and 20.3 ± 8.6 vs 17.7 ± 8.0) (P ≤ 0.0166). There was no significant difference between the two groups in signal-to-noise ratio, contrast-to-noise ratio, and subjective IQ of coronary arteries (29.4-31.7, 30.0-37.0, and medium score of 5 in group A vs 29.4-32.4, 27.7-36.3, and medium score of 5 in group B, respectively, P ≥ 0.1859). Both mean CTDI vol and dose length product in group B were 58% of those of group A. HCCM combined with low tube current allows dose reduction in coronary computed tomography angiography and does not compromise IQ. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  14. Steam generator tube failures

    International Nuclear Information System (INIS)

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service

  15. Validation of a Monte Carlo model used for simulating tube current modulation in computed tomography over a wide range of phantom conditions/challenges

    Energy Technology Data Exchange (ETDEWEB)

    Bostani, Maryam, E-mail: mbostani@mednet.ucla.edu; McMillan, Kyle; Cagnon, Chris H.; McNitt-Gray, Michael F. [Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90024 (United States); DeMarco, John J. [Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, California 90095 (United States)

    2014-11-01

    Purpose: Monte Carlo (MC) simulation methods have been widely used in patient dosimetry in computed tomography (CT), including estimating patient organ doses. However, most simulation methods have undergone a limited set of validations, often using homogeneous phantoms with simple geometries. As clinical scanning has become more complex and the use of tube current modulation (TCM) has become pervasive in the clinic, MC simulations should include these techniques in their methodologies and therefore should also be validated using a variety of phantoms with different shapes and material compositions to result in a variety of differently modulated tube current profiles. The purpose of this work is to perform the measurements and simulations to validate a Monte Carlo model under a variety of test conditions where fixed tube current (FTC) and TCM were used. Methods: A previously developed MC model for estimating dose from CT scans that models TCM, built using the platform of MCNPX, was used for CT dose quantification. In order to validate the suitability of this model to accurately simulate patient dose from FTC and TCM CT scan, measurements and simulations were compared over a wide range of conditions. Phantoms used for testing range from simple geometries with homogeneous composition (16 and 32 cm computed tomography dose index phantoms) to more complex phantoms including a rectangular homogeneous water equivalent phantom, an elliptical shaped phantom with three sections (where each section was a homogeneous, but different material), and a heterogeneous, complex geometry anthropomorphic phantom. Each phantom requires varying levels of x-, y- and z-modulation. Each phantom was scanned on a multidetector row CT (Sensation 64) scanner under the conditions of both FTC and TCM. Dose measurements were made at various surface and depth positions within each phantom. Simulations using each phantom were performed for FTC, detailed x–y–z TCM, and z-axis-only TCM to obtain

  16. Optimization of recommendations for abdomen computerized tomography based on reconstruction filters, voltage and tube current; Otimizacao de protocolos de tomografia computadorizada de abdome com base nos filtros de reconstrucao, tensao e corrente do tubo

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Vinicius da Costa

    2015-07-01

    The use of computed tomography has increased significantly over the past decades. In Brazil the use increased more than twofold from 2008 to 2014, in the meantime the abdomen procedures have tripled. The high frequency of this procedure combined by the increasing collective radiation dose in medical exposures, has resulted development tools to maximize the benefit in CT images. This work aimed to establish protocols optimized in abdominal CT through acquisitions parameters and reconstructions techniques based on filters kernels. A sample of patients undergoing abdominal CT in a diagnostic center of Rio de Janeiro was assessed. Had been collected patients information and acquisitions parameters. The phantoms CT image acquisitions were performed by using different voltage values by adjusting the tube current (mAs) to obtain the same value from CTDI{sub vol} patients with normal BMI. Afterwards, the CTDIvol values were reduced by 30%, 50% and 60%. All images were reconstructed with low-contrast filters (A) and standard filters (B). The CTDIvol values for patients with normal BMI were 7% higher than in patients with underweight BMI and 30%, 50% and 60% lower than the overweight, obese I and III patients, respectively. The evaluations of image quality showed that variation of the current (mA) and the reconstruction filters did not affect the Hounsfield values. When the contrast-to-noise ratio (CNR) was normalized to CTDIvol, the protocols acquired with 60% reduction of CTDIvol with 140 kV and 80 kV showed CNR 6% lower than the routine. Modifications of the acquisition parameters did not affect spatial resolution, but the post-processing with B filters reduced the spatial frequency by 16%. With reduced the dose of 30%, lesions in the spleen had the CNR higher than 10% routine protocols with 140 kV acquired and post-processed to filter A. The image post-processing with a filter A with a 80kV voltage provided CNR values equal to the routine for the liver lesions with a 30

  17. Hyperpolarization-activated current (In is reduced in hippocampal neurons from Gabra5-/- mice.

    Directory of Open Access Journals (Sweden)

    Robert P Bonin

    Full Text Available Changes in the expression of γ-aminobutyric acid type A (GABAA receptors can either drive or mediate homeostatic alterations in neuronal excitability. A homeostatic relationship between α5 subunit-containing GABAA (α5GABAA receptors that generate a tonic inhibitory conductance, and HCN channels that generate a hyperpolarization-activated cation current (Ih was recently described for cortical neurons, where a reduction in Ih was accompanied by a reciprocal increase in the expression of α5GABAA receptors resulting in the preservation of dendritosomatic synaptic function. Here, we report that in mice that lack the α5 subunit gene (Gabra5-/-, cultured embryonic hippocampal pyramidal neurons and ex vivo CA1 hippocampal neurons unexpectedly exhibited a decrease in Ih current density (by 40% and 28%, respectively, compared with neurons from wild-type (WT mice. The resting membrane potential and membrane hyperpolarization induced by blockade of Ih with ZD-7288 were similar in cultured WT and Gabra5-/- neurons. In contrast, membrane hyperpolarization measured after a train of action potentials was lower in Gabra5-/- neurons than in WT neurons. Also, membrane impedance measured in response to low frequency stimulation was greater in cultured Gabra5-/- neurons. Finally, the expression of HCN1 protein that generates Ih was reduced by 41% in the hippocampus of Gabra5-/- mice. These data indicate that loss of a tonic GABAergic inhibitory conductance was followed by a compensatory reduction in Ih. The results further suggest that the maintenance of resting membrane potential is preferentially maintained in mature and immature hippocampal neurons through the homeostatic co-regulation of structurally and biophysically distinct cation and anion channels.

  18. Analysis of the ways to decrease residual stresses on heat exchanging tubes and steam generator collector surfaces for reducing the material corrosion damage

    International Nuclear Information System (INIS)

    Stepanov, G.V.; Kharchenko, V.V.; Shatco, A.A.; Dranchenko, V.V.; Titov, V.F.

    1994-01-01

    Computer simulations have been carried out to analyze the effect of heat exchanger tube pressing forming process into a steam generator collector, on its residual stresses and strains. The program takes into consideration kinetic process peculiarities, material non-linear rheological properties, separate deformation of tubes and collectors in the presence of a clearance and their contact interaction, damage and crack appearance. 4 figs

  19. Is Africa’s current growth reducing inequality? Evidence from some selected african countries

    Directory of Open Access Journals (Sweden)

    Alege P.O.

    2015-06-01

    Full Text Available Is Africa’s current growth reducing inequality? What are the implications of growth on output performances in Africa? Does the effect of Africa’s growth on sectorial output have any implication for inequality in Africa? The study investigates the effect of shocks on a set of macroeconomic variables on inequality (measured by life expectancy and the implication of this on sectors that are perceived to provide economic empowerment in form of employment for people living in the African countries in our sample. Studies already find that growth in many African countries has not been accompanied with significant improvement in employment. Therefore inequality is subject to a counter cyclical trend in production levels when export destination countries experience a recession. The study also provides insight on the effect of growth on sectorial output for three major sectors in the African economy with the intent of analyzing the impact of growth on sectorial development. The method used in this study is Panel Vector Autoregressive (PVAR estimation and the obvious advantage of this method lies in the fact that it allows us to capture both static and dynamic interdependencies and to treat the links across units in an unrestricted fashion. Data is obtained from World Bank (WDI Statistics for the period 1985 to 2012 (28 years for 10 African Countries. Our main findings confirm strong negative relationship between GDP growth and life expectancy and also for GDP and the services and manufacturing sector considering the full sample.

  20. Chest Tube Management after Surgery for Pneumothorax.

    Science.gov (United States)

    Pompili, Cecilia; Salati, Michele; Brunelli, Alessandro

    2017-02-01

    There is scant evidence on the management of chest tubes after surgery for pneumothorax. Most of the current knowledge is extrapolated from studies performed on subjects with lung cancer. This article reviews the existing literature with particular focus on the effect of suction and no suction on the duration of air leak after lung resection and surgery for pneumothorax. Moreover, the role of regulated suction, which seems to provide some benefit in reducing pneumothorax recurrence after bullectomy and pleurodesis, is discussed. Finally, a personal view on the management of chest tubes after surgery for pneumothorax is provided. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Is multidetector CT-based bone mineral density and quantitative bone microstructure assessment at the spine still feasible using ultra-low tube current and sparse sampling?

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Kai; Kopp, Felix K.; Schwaiger, Benedikt J.; Gersing, Alexandra S.; Sauter, Andreas; Muenzel, Daniela; Rummeny, Ernst J. [Klinikum rechts der Isar, Technische Universitaet Muenchen, Department of Diagnostic and Interventional Radiology, Munich (Germany); Bippus, Rolf [Research Laboratories, Philips GmbH Innovative Technologies, Hamburg (Germany); Koehler, Thomas [Research Laboratories, Philips GmbH Innovative Technologies, Hamburg (Germany); Technische Universitaet Muenchen, TUM Institute for Advanced Studies, Garching (Germany); Fehringer, Andreas [Technische Universitaet Muenchen, Lehrstuhl fuer Biomedizinische Physik, Garching (Germany); Pfeiffer, Franz [Klinikum rechts der Isar, Technische Universitaet Muenchen, Department of Diagnostic and Interventional Radiology, Munich (Germany); Technische Universitaet Muenchen, TUM Institute for Advanced Studies, Garching (Germany); Technische Universitaet Muenchen, Lehrstuhl fuer Biomedizinische Physik, Garching (Germany); Kirschke, Jan S. [Klinikum rechts der Isar, Technische Universitaet Muenchen, Section of Diagnostic and Interventional Neuroradiology, Munich (Germany); Noel, Peter B. [Klinikum rechts der Isar, Technische Universitaet Muenchen, Department of Diagnostic and Interventional Radiology, Munich (Germany); Technische Universitaet Muenchen, Lehrstuhl fuer Biomedizinische Physik, Garching (Germany); Baum, Thomas [Klinikum rechts der Isar, Technische Universitaet Muenchen, Department of Diagnostic and Interventional Radiology, Munich (Germany); Klinikum rechts der Isar, Technische Universitaet Muenchen, Section of Diagnostic and Interventional Neuroradiology, Munich (Germany)

    2017-12-15

    Osteoporosis diagnosis using multidetector CT (MDCT) is limited to relatively high radiation exposure. We investigated the effect of simulated ultra-low-dose protocols on in-vivo bone mineral density (BMD) and quantitative trabecular bone assessment. Institutional review board approval was obtained. Twelve subjects with osteoporotic vertebral fractures and 12 age- and gender-matched controls undergoing routine thoracic and abdominal MDCT were included (average effective dose: 10 mSv). Ultra-low radiation examinations were achieved by simulating lower tube currents and sparse samplings at 50%, 25% and 10% of the original dose. BMD and trabecular bone parameters were extracted in T10-L5. Except for BMD measurements in sparse sampling data, absolute values of all parameters derived from ultra-low-dose data were significantly different from those derived from original dose images (p<0.05). BMD, apparent bone fraction and trabecular thickness were still consistently lower in subjects with than in those without fractures (p<0.05). In ultra-low-dose scans, BMD and microstructure parameters were able to differentiate subjects with and without vertebral fractures, suggesting osteoporosis diagnosis is feasible. However, absolute values differed from original values. BMD from sparse sampling appeared to be more robust. This dose-dependency of parameters should be considered for future clinical use. (orig.)

  2. Is multidetector CT-based bone mineral density and quantitative bone microstructure assessment at the spine still feasible using ultra-low tube current and sparse sampling?

    International Nuclear Information System (INIS)

    Mei, Kai; Kopp, Felix K.; Schwaiger, Benedikt J.; Gersing, Alexandra S.; Sauter, Andreas; Muenzel, Daniela; Rummeny, Ernst J.; Bippus, Rolf; Koehler, Thomas; Fehringer, Andreas; Pfeiffer, Franz; Kirschke, Jan S.; Noel, Peter B.; Baum, Thomas

    2017-01-01

    Osteoporosis diagnosis using multidetector CT (MDCT) is limited to relatively high radiation exposure. We investigated the effect of simulated ultra-low-dose protocols on in-vivo bone mineral density (BMD) and quantitative trabecular bone assessment. Institutional review board approval was obtained. Twelve subjects with osteoporotic vertebral fractures and 12 age- and gender-matched controls undergoing routine thoracic and abdominal MDCT were included (average effective dose: 10 mSv). Ultra-low radiation examinations were achieved by simulating lower tube currents and sparse samplings at 50%, 25% and 10% of the original dose. BMD and trabecular bone parameters were extracted in T10-L5. Except for BMD measurements in sparse sampling data, absolute values of all parameters derived from ultra-low-dose data were significantly different from those derived from original dose images (p<0.05). BMD, apparent bone fraction and trabecular thickness were still consistently lower in subjects with than in those without fractures (p<0.05). In ultra-low-dose scans, BMD and microstructure parameters were able to differentiate subjects with and without vertebral fractures, suggesting osteoporosis diagnosis is feasible. However, absolute values differed from original values. BMD from sparse sampling appeared to be more robust. This dose-dependency of parameters should be considered for future clinical use. (orig.)

  3. Dose and image quality in low-dose CT for urinary stone disease: added value of automatic tube current modulation and iterative reconstruction techniques

    International Nuclear Information System (INIS)

    Soenen, Olivier; Balliauw, Christophe; Oyen, Raymond; Zanca, Federica

    2017-01-01

    The aim of this study was to compare dose and image quality (IQ) of a baseline low-dose computed tomography (CT) (fix mAs) vs. an ultra-low-dose CT (automatic tube current modulation, ATCM) in patients with suspected urinary stone disease and to assess the added value of iterative reconstruction. CT examination was performed on 193 patients (103 baseline low-dose, 90 ultra-low-dose). Filtered back projection (FBP) was used for both protocols, and Sinogram Affirmed Iterative Reconstruction (SAFIRE) was used for the ultra-low-dose protocol only. Dose and ureter stones information were collected for both protocols. Subjective IQ was assessed by two radiologists scoring noise, visibility of the ureter and overall IQ. Objective IQ (contrast-to-noise ratio, CNR) was assessed for the ultra-low-dose protocol only (FBP and SAFIRE). The ultra-low-dose protocol (ATCM) showed a 22% decrease in mean effective dose ( p < 0.001) and improved visibility of the pelvic ureter (p = 0.02). CNR was higher for SAFIRE (p < 0.0001). SAFIRE improves the objective IQ, but not the subjective IQ for the chosen clinical task. (authors)

  4. SU-G-IeP2-05: Effect of Localizer Type and Patient Off-Centering On CT Radiation Dose with Use of Automatic Tube Current Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, C; Sodickson, A; Hamberg, L [Brigham and Women’s Hospital, Boston, MA (United States)

    2016-06-15

    Purpose: Apparent patient size in CT localizers varies with localizer type and patient positioning, resulting in variation in effective mAs as guided by Tube Current Modulation (TCM). Our aim was to investigate the effects of vertical off-centering on CTDI-vol when using different localizer types and TCM strengths. Methods: A CTDI body phantom was scanned using an abdominal protocol with three TCM strengths (Siemens Definition AS40, CAREDose4D; very weak, average, very strong). Data was acquired at 11 table height positions; with phantom center at isocenter and at 10 other positions between 142mm below and 53mm above. At each position, scans were acquired using 5 different localizer types: PA, AP, Lateral, PA+Lateral, and Lateral+PA. CTDI-vol was recorded for the 165 combinations of table height, localizer type, and TCM strength, and magnification factors measured from localizer images. Results: Magnification factors from AP and PA localizers ranged from 0.79–1.11 and 1.35–0.91, respectively from lowest to highest positions (highest with phantom located closest to X-ray tube), with a smaller impact when using Lateral, PA+Lateral, Lateral+PA localizer types, all of which behaved similarly. For an average TCM strength and PA localizer, CTDI-vol ranged from 75% higher to 12% lower than the isocenter value for the lowest to highest table positions, respectively. For table positions ranging from lowest to highest, CTDI-vol ranged from −23% to 17% for AP, from −8% to 0.3% for lateral and from −7% to 1% for a combination of PA and Lateral in either order. Similar behavior was found for different TCM strengths, but effects were more pronounced for very strong compared with very weak modulation strengths. Conclusion: Patient off-centering substantially impacts radiation dose, which depends on the amount of vertical offcentering and type of the localizer used. The combination of PA and Lateral localizers is most robust against effects of patient off-centering.

  5. SU-G-IeP2-05: Effect of Localizer Type and Patient Off-Centering On CT Radiation Dose with Use of Automatic Tube Current Modulation

    International Nuclear Information System (INIS)

    Ruan, C; Sodickson, A; Hamberg, L

    2016-01-01

    Purpose: Apparent patient size in CT localizers varies with localizer type and patient positioning, resulting in variation in effective mAs as guided by Tube Current Modulation (TCM). Our aim was to investigate the effects of vertical off-centering on CTDI-vol when using different localizer types and TCM strengths. Methods: A CTDI body phantom was scanned using an abdominal protocol with three TCM strengths (Siemens Definition AS40, CAREDose4D; very weak, average, very strong). Data was acquired at 11 table height positions; with phantom center at isocenter and at 10 other positions between 142mm below and 53mm above. At each position, scans were acquired using 5 different localizer types: PA, AP, Lateral, PA+Lateral, and Lateral+PA. CTDI-vol was recorded for the 165 combinations of table height, localizer type, and TCM strength, and magnification factors measured from localizer images. Results: Magnification factors from AP and PA localizers ranged from 0.79–1.11 and 1.35–0.91, respectively from lowest to highest positions (highest with phantom located closest to X-ray tube), with a smaller impact when using Lateral, PA+Lateral, Lateral+PA localizer types, all of which behaved similarly. For an average TCM strength and PA localizer, CTDI-vol ranged from 75% higher to 12% lower than the isocenter value for the lowest to highest table positions, respectively. For table positions ranging from lowest to highest, CTDI-vol ranged from −23% to 17% for AP, from −8% to 0.3% for lateral and from −7% to 1% for a combination of PA and Lateral in either order. Similar behavior was found for different TCM strengths, but effects were more pronounced for very strong compared with very weak modulation strengths. Conclusion: Patient off-centering substantially impacts radiation dose, which depends on the amount of vertical offcentering and type of the localizer used. The combination of PA and Lateral localizers is most robust against effects of patient off-centering.

  6. Reducing Multisensor Satellite Monthly Mean Aerosol Optical Depth Uncertainty: 1. Objective Assessment of Current AERONET Locations

    Science.gov (United States)

    Li, Jing; Li, Xichen; Carlson, Barbara E.; Kahn, Ralph A.; Lacis, Andrew A.; Dubovik, Oleg; Nakajima, Teruyuki

    2016-01-01

    Various space-based sensors have been designed and corresponding algorithms developed to retrieve aerosol optical depth (AOD), the very basic aerosol optical property, yet considerable disagreement still exists across these different satellite data sets. Surface-based observations aim to provide ground truth for validating satellite data; hence, their deployment locations should preferably contain as much spatial information as possible, i.e., high spatial representativeness. Using a novel Ensemble Kalman Filter (EnKF)- based approach, we objectively evaluate the spatial representativeness of current Aerosol Robotic Network (AERONET) sites. Multisensor monthly mean AOD data sets from Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, Sea-viewing Wide Field-of-view Sensor, Ozone Monitoring Instrument, and Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar are combined into a 605-member ensemble, and AERONET data are considered as the observations to be assimilated into this ensemble using the EnKF. The assessment is made by comparing the analysis error variance (that has been constrained by ground-based measurements), with the background error variance (based on satellite data alone). Results show that the total uncertainty is reduced by approximately 27% on average and could reach above 50% over certain places. The uncertainty reduction pattern also has distinct seasonal patterns, corresponding to the spatial distribution of seasonally varying aerosol types, such as dust in the spring for Northern Hemisphere and biomass burning in the fall for Southern Hemisphere. Dust and biomass burning sites have the highest spatial representativeness, rural and oceanic sites can also represent moderate spatial information, whereas the representativeness of urban sites is relatively localized. A spatial score ranging from 1 to 3 is assigned to each AERONET site based on the uncertainty

  7. High transport current superconductivity in powder-in-tube Ba0.6K0.4Fe2As2 tapes at 27 T

    Science.gov (United States)

    Huang, He; Yao, Chao; Dong, Chiheng; Zhang, Xianping; Wang, Dongliang; Cheng, Zhe; Li, Jianqi; Awaji, Satoshi; Wen, Haihu; Ma, Yanwei

    2018-01-01

    The high upper critical field and low anisotropy of iron-based superconductors (IBS) make them particularly attractive for high-field applications, especially for the construction of next-generation nuclear magnetic resonance spectrometers, particle accelerators and high-field magnets. However, for practical use it is essential to make IBS materials into wire and tape conductors with sufficient current carrying capability, which is limited by misaligned grains inside the conductors. Here, based on a simple and low-cost powder-in-tube (PIT) method, we demonstrate a high transport critical current density (J c) reaching 1.5 × 105 A cm-2 (I c = 437 A) at 4.2 K and 10 T in Ba0.6K0.4Fe2As2 (Ba-122) tapes by texturing the grain orientation with optimized hot-press technique. The transport J c measured at 4.2 K under high magnetic fields of 27 T is still on the level of 5.5 × 104 A cm-2. Moreover, at 20 K and 5 T the transport J c is also as high as 5.4 × 104 A cm-2, showing a promising application potential in moderate temperature range which can be reached by liquid hydrogen or cryogenic cooling. All these J c values are the highest ever reported for IBS wires and tapes. The high-performance PIT Ba-122 tapes in this work suggest IBS to be a strong potential competitor of cuprate superconductors for the race of high-field applications in the future.

  8. Tubing misconnections: normalization of deviance.

    Science.gov (United States)

    Simmons, Debora; Symes, Lene; Guenter, Peggi; Graves, Krisanne

    2011-06-01

    Accidental connection of an enteral system to an intravenous (IV) system frequently results in the death of the patient. Misconnections are commonly attributed to the presence of universal connectors found in the majority of patient care tubing systems. Universal connectors allow for tubing misconnections between physiologically incompatible systems. The purpose of this review of case studies of tubing misconnections and of current expert recommendations for safe tubing connections was to answer the following questions: In tubing connections that have the potential for misconnections between enteral and IV tubing, what are the threats to safety? What are patient outcomes following misconnections between enteral and IV tubing? What are the current recommendations for preventing misconnections between enteral and IV tubing? Following an extensive literature search and guided by 2 models of threats and errors, the authors analyzed case studies and expert opinions to identify technical, organizational, and human errors; patient-related threats; patient outcomes; and recommendations. A total of 116 case studies were found in 34 publications. Each involved misconnections of tubes carrying feedings, intended for enteral routes, to IV lines. Overwhelmingly, the recommendations were for redesign to eliminate universal connectors and prevent misconnections. Other recommendations were made, but the analysis indicates they would not prevent all misconnections. This review of the published case studies and current expert recommendations supports a redesign of connectors to ensure incompatibility between enteral and IV systems. Despite the cumulative evidence, little progress has been made to safeguard patients from tubing misconnections.

  9. Evaluation of the crack initiation of curved compact tension specimens of a Zr-2.5Nb pressure tube using the unloading compliance and direct current potential drop methods

    International Nuclear Information System (INIS)

    Jeong, Hyeon Cheol; Ahn, Sang Bok; Park, Joong Chul; Kim, Young Suk

    2005-01-01

    Zr-2.5Nb pressure tubes, carrying fuel bundles and heavy water coolant inside, degrade due to neutron irradiation and hydrogen embrittlement during their operation in heavy water reactors. The safety criterion for the Zr-2.5Nb tubes to meet is a leak-before-break (LBB) requirement. To evaluate a safety margin related to the LBB criterion, facture toughness of the pressure tubes are to be determined periodically with their operational time. For a reliable evaluation of the LBB safety criterion of the pressure tubes, it is required to precisely determine their fracture toughness. Since the fracture toughness or J of the pressure tubes is determined only by the extended crack length, it is important to reliably and precisely evaluate the advanced crack length. However, the problem lies with the detection of the crack opening point because prior plastic deformation before a start of the crack makes it difficult. The aim of this work is to evaluate which method can define the crack initiation point in the Zr- 2.5Nb compact tension specimens more precisely between the unloading compliance method with a crack opening displacement (COD) gauge and the direct current potential drop (DCPD) methods

  10. Reducing the beam current in Linac4 in pulse to pulse mode.

    CERN Document Server

    Lallement, JB; CERN. Geneva. BE Department

    2009-01-01

    In order to deliver different beam intensities to users, we studied the possibility of varying the Linac4 beam current at PS Booster injection in pulse to pulse mode. This report gives the possible configurations of Linac4 Low and Medium Energy Beam Transport lines (LEBT and MEBT) that lead to a consistent current reduction.

  11. Hypoglossal-facial anastomosis (HFA) over a 10 mm gap bridged by a Y-tube-conduit enhances neurite regrowth and reduces collateral axonal branching at the lesion site.

    Science.gov (United States)

    Ozsoy, Umut; Demirel, Bahadir Murat; Hizay, Arzu; Ozsoy, Ozlem; Ankerne, Janina; Angelova, Srebrina; Sarikcioglu, Levent; Ucar, Yasar; Angelov, Doychin N

    2011-01-01

    The outcome of severe peripheral nerve injuries requiring surgical repair (transection and suture) is usually poor. Recent work suggests that direct suture of nerves increases collagen production and provides unfavourable conditions for a proper axonal regrowth. We tested whether entubulation of the hypoglossal nerve into a Y-tube conduit connecting it with the zygomatic and buccal facial nerve branches would improve axonal pathfinding at the lesion site, quality of muscle reinnervation and recovery of vibrissal whisking. For hypoglossal-facial anastomosis (HFA) over a Y-tube (HFA-Y-tube) the proximal stump of the hypoglossal nerve was entubulated and sutured into the long arm of a Y-tube (isogeneic abdominal aorta with its bifurcation). The zygomatic and buccal facial branches were entubulated and sutured to the short arms of the Y-tube. Restoration of vibrissal motor performance, degree of collateral axonal branching at the lesion site and quality of neuro-muscular junction (NMJ) reinnervation were compared to animals receiving HFA-Coaptation (no entubulation) after 4 months. HFA-Y-tube reduced collateral axonal branching. However it failed to reduce the proportion of polyinnervated NMJ and did not improve functional outcome when compared to HFA-Coaptation. Elimination of compression by tightly opposed nerve fragments improved axonal pathfinding. However, biometric analysis of vibrissae movements did not show positive effects suggesting that polyneuronal reinnervation - rather than collateral branching - may be the critical limiting factor. Since polyinnervation of muscle fibers is activity-dependent and can be manipulated, the present findings raise hopes that clinically feasible and effective therapies after HFA could be soon designed and tested.

  12. Influence of particle size of Mg powder on the microstructure and critical currents of in situ powder-in-tube processed MgB_2 wires

    International Nuclear Information System (INIS)

    Kumakura, Hiroaki; Ye, Shujun; Matsumoto, Akiyoshi; Nitta, Ryuji

    2016-01-01

    We fabricated in situ powder-in-tube(PIT) MgB_2 wires using three kinds of Mg powders with particle size of ∼45 μm, ∼150 μm and 212∼600 μm. Mg particles were elongated to filamentary structure in the wires during cold drawing process. Especially, long Mg filamentary structure was obtained for large Mg particle size of 212∼600 μm. Critical current density, J_c, increased with increasing Mg particle size for 1 mm diameter wires. This is due to the development of filamentary structure of high density MgB_2 superconducting layer along the wires. This MgB_2 structure is similar to that of the internal Mg diffusion (IMD) processed MgB_2 wires. However, J_c of the wires fabricated with 212∼600 μm Mg particle size decreased and the scattering of J_c increased with decreasing wire diameter, while the J_c of the wires with ∼45 μm Mg particle was almost independent of the wire diameter. The cross sectional area reduction of the Mg particles during the wire drawing is smaller than that of the wire. When using large size Mg particle, the number of Mg filaments in the wire cross section is small. These two facts statistically lead to the larger scattering of Mg areal fraction in the wire cross section with proceeding of wire drawing process, resulting in smaller volume fraction of MgB_2 in the wire and lower J_c with larger scattering along the wire. SiC nano powder addition is effective in increasing J_c for all Mg particle sizes. (author)

  13. Heat Exchanger Tube to Tube Sheet Joints Corrosion Behavior

    Directory of Open Access Journals (Sweden)

    M. Iancu

    2013-03-01

    Full Text Available Paper presents the studies made by the authors above the tube to tube sheet fittings of heat exchanger with fixed covers from hydrofining oil reforming unit. Tube fittings are critical zones for heat exchangers failures. On a device made from material tube and tube sheet at real joints dimensions were establish axial compression force and traction force at which tube is extracted from expanded joint. Were used two shapes joints with two types of fittings surfaces, one with smooth hole of tube sheet and other in which on boring surface we made a groove. From extracted expanded tube zones were made samples for corrosion tests in order to establish the corrosion rate, corrosion potential and corrosion current in working mediums such as hydrofining oil and industrial water at different temperatures. The corrosion rate values and the temperature influence are important to evaluate joints durability and also the results obtained shows that the boring tube sheet shape with a groove on hole tube shape presents a better corrosion behavior then the shape with smooth hole tube sheet.

  14. Glutathionylation-Dependence of Na+-K+-Pump Currents Can Mimic Reduced Subsarcolemmal Na+ Diffusion

    Science.gov (United States)

    Garcia, Alvaro; Liu, Chia-Chi; Cornelius, Flemming; Clarke, Ronald J.; Rasmussen, Helge H.

    2016-01-01

    The existence of a subsarcolemmal space with restricted diffusion for Na+ in cardiac myocytes has been inferred from a transient peak electrogenic Na+-K+ pump current beyond steady state on reexposure of myocytes to K+ after a period of exposure to K+-free extracellular solution. The transient peak current is attributed to enhanced electrogenic pumping of Na+ that accumulated in the diffusion-restricted space during pump inhibition in K+-free extracellular solution. However, there are no known physical barriers that account for such restricted Na+ diffusion, and we examined if changes of activity of the Na+-K+ pump itself cause the transient peak current. Reexposure to K+ reproduced a transient current beyond steady state in voltage-clamped ventricular myocytes as reported by others. Persistence of it when the Na+ concentration in patch pipette solutions perfusing the intracellular compartment was high and elimination of it with K+-free pipette solution could not be reconciled with restricted subsarcolemmal Na+ diffusion. The pattern of the transient current early after pump activation was dependent on transmembrane Na+- and K+ concentration gradients suggesting the currents were related to the conformational poise imposed on the pump. We examined if the currents might be accounted for by changes in glutathionylation of the β1 Na+-K+ pump subunit, a reversible oxidative modification that inhibits the pump. Susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na+-K+ pump, and glutathionylation with the pump stabilized in conformations equivalent to those expected to be imposed on voltage-clamped myocytes supported this hypothesis. So did elimination of the transient K+-induced peak Na+-K+ pump current when we included glutaredoxin 1 in patch pipette solutions to reverse glutathionylation. We conclude that transient K+-induced peak Na+-K+ pump current reflects the effect of conformation-dependent β1 pump subunit

  15. Feeding Tubes

    Science.gov (United States)

    ... feeding therapies have been exhausted. Please review product brand and method of placement carefully with your physician ... Total Parenteral Nutrition. Resources: Oley Foundation Feeding Tube Awareness Foundation Children’s Medical Nutrition Alliance APFED’s Educational Webinar ...

  16. Glutathionylation-Dependence of Na+-K+-Pump Currents Can Mimic Reduced Subsarcolemmal Na+ Diffusion

    OpenAIRE

    Garcia, Alvaro; Liu, Chia-Chi; Cornelius, Flemming; Clarke, Ronald?J.; Rasmussen, Helge?H.

    2016-01-01

    The existence of a subsarcolemmal space with restricted diffusion for Na+ in cardiac myocytes has been inferred from a transient peak electrogenic Na+-K+ pump current beyond steady state on reexposure of myocytes to K+ after a period of exposure to K+-free extracellular solution. The transient peak current is attributed to enhanced electrogenic pumping of Na+ that accumulated in the diffusion-restricted space during pump inhibition in K+-free extracellular solution. However, there are no know...

  17. Fabrication of seamless calandria tubes

    International Nuclear Information System (INIS)

    Saibaba, N.; Phanibabu, C.; Bhaskara Rao, C.V.; Kalidas, R.; Ganguly, C.

    2002-01-01

    Full text: Calandria tube is a large diameter, thin walled zircaloy-4 tube and is an important structural component of PHWR type of reactors. These tubes are lifetime components and remain during the full life of the reactor. Calandria tubes are classified as extremely thin walled tubes with a diameter to wall thickness ratio of around 96. Such thin walled tubes are conventionally produced by seam welded route comprising of extrusion of slabs followed by a series of hot and rolling passes, shaping into O-shape and eventual welding. An alternative and superior method of fabricating the calandria tubes, the seamless route, has been developed, which involves hot extrusion of mother blanks followed by three successive cold pilger reductions. Eccentricity correction of the extruded blanks is carried out on a special purpose grinding equipment to bring the wall thickness variation within permissible limits. Predominant wall thickness reductions are given during cold pilgering to ensure high Q-factor values. The texture in the finished tubes could be closely, controlled with an average f r value of 0.65. Pilgering parameters and tube guiding system have been specially designed to facilities rolling of thin walled tubes. Seamless calandria tubes have distinct advantages over welded tubes. In addition to the absence of weld, they are dimensionally more stable, lighter in weight and possess uniform grains with superior grain size. The cycle time from billet to finished product is substantially reduced and the product is amenable to high level of quality assurance. The most significant feature of the seamless route is its material recovery over welded route. Residual stresses measured in the tubes indicate that these are negligible and uniform along the length of the tube. In view of their superior quality, the first charge of seamless calandria tubes will be rolled into the first 500 MWe Pressurised Heavy Water Reactor at Tarapur

  18. Polymer multilayers loaded with antifungal β-peptides kill planktonic Candida albicans and reduce formation of fungal biofilms on the surfaces of flexible catheter tubes.

    Science.gov (United States)

    Raman, Namrata; Lee, Myung-Ryul; Palecek, Sean P; Lynn, David M

    2014-10-10

    Candida albicans is the most common fungal pathogen responsible for hospital-acquired infections. Most C. albicans infections are associated with the implantation of medical devices that act as points of entry for the pathogen and as substrates for the growth of fungal biofilms that are notoriously difficult to eliminate by systemic administration of conventional antifungal agents. In this study, we report a fill-and-purge approach to the layer-by-layer fabrication of biocompatible, nanoscale 'polyelectrolyte multilayers' (PEMs) on the luminal surfaces of flexible catheters, and an investigation of this platform for the localized, intraluminal release of a cationic β-peptide-based antifungal agent. We demonstrate that polyethylene catheter tubes with luminal surfaces coated with multilayers ~700nm thick fabricated from poly-l-glutamic acid (PGA) and poly-l-lysine (PLL) can be loaded, post-fabrication, by infusion with β-peptide, and that this approach promotes extended intraluminal release of this agent (over ~4months) when incubated in physiological media. The β-peptide remained potent against intraluminal inoculation of the catheters with C. albicans and substantially reduced the formation of C. albicans biofilms on the inner surfaces of film-coated catheters. Finally, we report that these β-peptide-loaded coatings exhibit antifungal activity under conditions that simulate intermittent catheter use and microbial challenge for at least three weeks. We conclude that β-peptide-loaded PEMs offer a novel and promising approach to kill C. albicans and prevent fungal biofilm formation on surfaces, with the potential to substantially reduce the incidence of device-associated infections in indwelling catheters. β-Peptides comprise a promising new class of antifungal agents that could help address problems associated with the use of conventional antifungal agents. The versatility of the layer-by-layer approach used here thus suggests additional opportunities to

  19. Glutathionylation-Dependence of Na(+)-K(+)-Pump Currents Can Mimic Reduced Subsarcolemmal Na(+) Diffusion.

    Science.gov (United States)

    Garcia, Alvaro; Liu, Chia-Chi; Cornelius, Flemming; Clarke, Ronald J; Rasmussen, Helge H

    2016-03-08

    The existence of a subsarcolemmal space with restricted diffusion for Na(+) in cardiac myocytes has been inferred from a transient peak electrogenic Na(+)-K(+) pump current beyond steady state on reexposure of myocytes to K(+) after a period of exposure to K(+)-free extracellular solution. The transient peak current is attributed to enhanced electrogenic pumping of Na(+) that accumulated in the diffusion-restricted space during pump inhibition in K(+)-free extracellular solution. However, there are no known physical barriers that account for such restricted Na(+) diffusion, and we examined if changes of activity of the Na(+)-K(+) pump itself cause the transient peak current. Reexposure to K(+) reproduced a transient current beyond steady state in voltage-clamped ventricular myocytes as reported by others. Persistence of it when the Na(+) concentration in patch pipette solutions perfusing the intracellular compartment was high and elimination of it with K(+)-free pipette solution could not be reconciled with restricted subsarcolemmal Na(+) diffusion. The pattern of the transient current early after pump activation was dependent on transmembrane Na(+)- and K(+) concentration gradients suggesting the currents were related to the conformational poise imposed on the pump. We examined if the currents might be accounted for by changes in glutathionylation of the β1 Na(+)-K(+) pump subunit, a reversible oxidative modification that inhibits the pump. Susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na(+)-K(+) pump, and glutathionylation with the pump stabilized in conformations equivalent to those expected to be imposed on voltage-clamped myocytes supported this hypothesis. So did elimination of the transient K(+)-induced peak Na(+)-K(+) pump current when we included glutaredoxin 1 in patch pipette solutions to reverse glutathionylation. We conclude that transient K(+)-induced peak Na(+)-K(+) pump current reflects the effect

  20. Insulin reduces neuronal excitability by turning on GABA(A channels that generate tonic current.

    Directory of Open Access Journals (Sweden)

    Zhe Jin

    Full Text Available Insulin signaling to the brain is important not only for metabolic homeostasis but also for higher brain functions such as cognition. GABA (γ-aminobutyric acid decreases neuronal excitability by activating GABA(A channels that generate phasic and tonic currents. The level of tonic inhibition in neurons varies. In the hippocampus, interneurons and dentate gyrus granule cells normally have significant tonic currents under basal conditions in contrast to the CA1 pyramidal neurons where it is minimal. Here we show in acute rat hippocampal slices that insulin (1 nM "turns on" new extrasynaptic GABA(A channels in CA1 pyramidal neurons resulting in decreased frequency of action potential firing. The channels are activated by more than million times lower GABA concentrations than synaptic channels, generate tonic currents and show outward rectification. The single-channel current amplitude is related to the GABA concentration resulting in a single-channel GABA affinity (EC(50 in intact CA1 neurons of 17 pM with the maximal current amplitude reached with 1 nM GABA. They are inhibited by GABA(A antagonists but have novel pharmacology as the benzodiazepine flumazenil and zolpidem are inverse agonists. The results show that tonic rather than synaptic conductances regulate basal neuronal excitability when significant tonic conductance is expressed and demonstrate an unexpected hormonal control of the inhibitory channel subtypes and excitability of hippocampal neurons. The insulin-induced new channels provide a specific target for rescuing cognition in health and disease.

  1. Measurements of electrically exploded tubes

    International Nuclear Information System (INIS)

    Shearer, J.W.; Hartman, C.W.; Munger, R.H.; Gullickson, R.L.; Trimble, D.O.; Cheng, D.Y.

    1975-01-01

    The dynamics of electrically exploded tubes were investigated, principally by means of current measurements and flash x-ray pictures. The pinch effect was observed on the tube motion. Pileup of the imploding tube metal was seen on axis. An approximate analytical model can be roughly fitted to the data, but a more complete fit can be obtained with detailed numerical codes. Application of the results to the planning of future gas-embedded Z-pinch experiments is discussed. (U.S.)

  2. Copper current collectors reduce long-term fouling of air cathodes in microbial fuel cells

    KAUST Repository

    Myung, Jaewook; Yang, Wulin; Saikaly, Pascal; Logan, Bruce E

    2018-01-01

    Long-term operation of wastewater-fed, microbial fuel cells (MFCs) with cathodes made of activated carbon and stainless steel (SS) current collectors can result in decreased performance due to cathode fouling. Copper has good antimicrobial properties, and it is more electrically conductive than SS. To demonstrate that a copper current collector could produce a more fouling resistant cathode, MFCs with air cathodes using either SS or copper current collectors were operated using domestic wastewater for 27 weeks. The reduction in biofouling over time was shown by less biofilm formation on the copper cathode surface compared to SS cathodes, due to the antimicrobial properties of copper. Maximum power densities from 17–27 weeks were 440 ± 38 mW/m2 using copper and 370 ± 21 mW/m2 using SS cathodes. The main difference in the microbial community was a nitrifying community on the SS cathodes, which was not present on the copper cathodes.

  3. Copper current collectors reduce long-term fouling of air cathodes in microbial fuel cells

    KAUST Repository

    Myung, Jaewook

    2018-02-05

    Long-term operation of wastewater-fed, microbial fuel cells (MFCs) with cathodes made of activated carbon and stainless steel (SS) current collectors can result in decreased performance due to cathode fouling. Copper has good antimicrobial properties, and it is more electrically conductive than SS. To demonstrate that a copper current collector could produce a more fouling resistant cathode, MFCs with air cathodes using either SS or copper current collectors were operated using domestic wastewater for 27 weeks. The reduction in biofouling over time was shown by less biofilm formation on the copper cathode surface compared to SS cathodes, due to the antimicrobial properties of copper. Maximum power densities from 17–27 weeks were 440 ± 38 mW/m2 using copper and 370 ± 21 mW/m2 using SS cathodes. The main difference in the microbial community was a nitrifying community on the SS cathodes, which was not present on the copper cathodes.

  4. Influence of tube voltage on CT attenuation, radiation dose, and image quality: phantom study

    International Nuclear Information System (INIS)

    Li Fengtan; Li Dong; Zhang Yunting

    2013-01-01

    Objective: To assess the influence of tube current and tube voltage on the CT attenuation, radiation dose, and image quality. Methods: A total of 113 saline solutions with decreasing dilution of contrast medium (370 mg I/ml) was produced. MDCT scan was performed with 15 series of different settings of tube current and tube voltage. CT attenuations with 15 series of different settings were all measured, and influence of tube current and tube voltage on CT attenuations was analyzed. CT dose index (CTDIvol) was recorded. The CT attenuations with different tube voltage and current were compared with one-way ANOVA and Kruskal-Wallis rank sum test. The correlation of CT attenuation with different tube voltage and the influence of tube voltage and current on radiation dose and image quality were tested by correlation analysis. Results: Tube current (250, 200, 150, 100, and 50 mA) had no significant effect on CT attenuation (F = 0.001, 0.008, 0.075, P > 0.05), while tube voltage (120, 100, and 80 kV) had significant effect (H = 17.906, 17.906, 13.527, 20.124, 23.563, P < 0.05). The correlation between CT attenuation and tube voltage was determined with equation: CT attenuatio N_1_0_0 _k_V = 1.561 × CT attenuatio N_1_2_0 _k_v + 4.0818, CT attenuatio N_8_0 _k_v = 1.2131 × CT attenuatio N_1_2_0 _k_v + 0.9283. The influence of tube voltage on radiation dose and image quality was also analyzed, and equations were also obtained: N_1_2_0 -k_v = -5.9771 Ln (D_1_2_0 kv) + 25.412, N_1_0_0 _k_v = -10.544 Ln (D_1_0_0 _k_v) + 36.262, N_8_0 _k_v = -25.326 Ln (D_8_0 _k_v) + 62.816. According to the results of relationship among CT attenuation, radiation dose, and image quality, lower tube voltage with higher tube current can reduce the radiation dose. Conclusions: Lower tube voltage can reduce the radiation dose. However, CT attenuation was influenced, and correction should be done with the equations. (authors)

  5. Steam generator tube extraction

    International Nuclear Information System (INIS)

    Delorme, H.

    1985-05-01

    To enable tube examination on steam generators in service, Framatome has now developed a process for removing sections of steam generator tubes. Tube sections can be removed without being damaged for treating the tube section expanded in the tube sheet

  6. Highly Conformal Ni Micromesh as a Current Collecting Front Electrode for Reduced Cost Si Solar Cell

    DEFF Research Database (Denmark)

    Gupta, Nikita; Rao, K. D. M.; Gupta, Ritu

    2017-01-01

    deposition of Ni wire network on corrugated solar cell, a short circuit current of 33.28 mA/cm2 was obtained in comparison to 20.53 mA/cm2 without the network electrode. On comparing the efficiency with the conventional cells with screen printed electrodes, a 20% increment in efficiency has been observed...

  7. Reducing condition number by appropriate current decomposition on a multiplet of several wires

    CSIR Research Space (South Africa)

    Lysko, AA

    2011-07-01

    Full Text Available This paper discusses a numerical investigation in connection with the dependency of the condition number of the impedance matrix on the decomposition of current on a junction with several attached wires (multiplet). It is shown that the condition...

  8. Reducing food wastage, improving food security? An inventory study on stakeholders’ perspectives and the current state

    NARCIS (Netherlands)

    Tielens, J.; Candel, J.J.L.

    2014-01-01

    This study is concerned with the relation between food wastage reduction and the improvement of food security. The central question of this inventory study is to what extent interventions to reduce food wastage are effective contributions for food security, in particular for local access in

  9. Expanding the reduced-current approach for thermoelectric generators to achieve higher volumetric power density

    DEFF Research Database (Denmark)

    Wijesooriyage, Waruna Dissanayaka; Rosendahl, Lasse

    2015-01-01

    Thermoelectrics are candidate niche electrical generator devices for energy management. At present, scientists are more focused on thermoelectric (TE) material development, but the TE module design procedure is still in a relatively virgin state. One of the most well-known methods is the reduced ...

  10. In service inspection for steam generator tubes

    International Nuclear Information System (INIS)

    Comby, R.; Eyrolles, Ph.

    1988-01-01

    In this paper the authors show the means putting in place for examination of steam generators tubes. These means (eddy current probes, ultrasonic testing) associated with a knowledge on degradation phenomena allow mapping controlled tubes and limiting undesirable obturations [fr

  11. Image Quality and Radiation Dose of CT Coronary Angiography with Automatic Tube Current Modulation and Strong Adaptive Iterative Dose Reduction Three-Dimensional (AIDR3D.

    Directory of Open Access Journals (Sweden)

    Hesong Shen

    Full Text Available To investigate image quality and radiation dose of CT coronary angiography (CTCA scanned using automatic tube current modulation (ATCM and reconstructed by strong adaptive iterative dose reduction three-dimensional (AIDR3D.Eighty-four consecutive CTCA patients were collected for the study. All patients were scanned using ATCM and reconstructed with strong AIDR3D, standard AIDR3D and filtered back-projection (FBP respectively. Two radiologists who were blinded to the patients' clinical data and reconstruction methods evaluated image quality. Quantitative image quality evaluation included image noise, signal-to-noise ratio (SNR, and contrast-to-noise ratio (CNR. To evaluate image quality qualitatively, coronary artery is classified into 15 segments based on the modified guidelines of the American Heart Association. Qualitative image quality was evaluated using a 4-point scale. Radiation dose was calculated based on dose-length product.Compared with standard AIDR3D, strong AIDR3D had lower image noise, higher SNR and CNR, their differences were all statistically significant (P<0.05; compared with FBP, strong AIDR3D decreased image noise by 46.1%, increased SNR by 84.7%, and improved CNR by 82.2%, their differences were all statistically significant (P<0.05 or 0.001. Segments with diagnostic image quality for strong AIDR3D were 336 (100.0%, 486 (96.4%, and 394 (93.8% in proximal, middle, and distal part respectively; whereas those for standard AIDR3D were 332 (98.8%, 472 (93.7%, 378 (90.0%, respectively; those for FBP were 217 (64.6%, 173 (34.3%, 114 (27.1%, respectively; total segments with diagnostic image quality in strong AIDR3D (1216, 96.5% were higher than those of standard AIDR3D (1182, 93.8% and FBP (504, 40.0%; the differences between strong AIDR3D and standard AIDR3D, strong AIDR3D and FBP were all statistically significant (P<0.05 or 0.001. The mean effective radiation dose was (2.55±1.21 mSv.Compared with standard AIDR3D and FBP, CTCA

  12. Detecting Intracranial Hemorrhage Using Automatic Tube Current Modulation With Advanced Modeled Iterative Reconstruction in Unenhanced Head Single- and Dual-Energy Dual-Source CT.

    Science.gov (United States)

    Scholtz, Jan-Erik; Wichmann, Julian L; Bennett, Dennis W; Leithner, Doris; Bauer, Ralf W; Vogl, Thomas J; Bodelle, Boris

    2017-05-01

    The purpose of our study was to determine diagnostic accuracy, image quality, and radiation dose of low-dose single- and dual-energy unenhanced third-generation dual-source head CT for detection of intracranial hemorrhage (ICH). A total of 123 patients with suspected ICH were examined using a dual-source 192-MDCT scanner. Standard-dose 120-kVp single-energy CT (SECT; n = 36) and 80-kVp and 150-kVp dual-energy CT (DECT; n = 30) images were compared with low-dose SECT (n = 32) and DECT (n = 25) images obtained using automated tube current modulation (ATCM). Advanced modeled iterative reconstruction (ADMIRE) was used for all protocols. Detection of ICH was performed by three readers who were blinded to the image acquisition parameters of each image series. Image quality was assessed both quantitatively and qualitatively. Interobserver agreement was calculated using the Fleiss kappa. Radiation dose was measured as dose-length product (DLP). Detection of ICH was excellent (sensitivity, 94.9-100%; specificity, 94.7-100%) in all protocols (p = 1.00) with perfect interobserver agreement (0.83-0.96). Qualitative ratings showed significantly better ratings for both standard-dose protocols regarding gray matter-to-white matter contrast (p ≤ 0.014), whereas highest gray matter-to-white matter contrast-to-noise ratio was observed with low-dose DECT images (p ≥ 0.057). The lowest posterior fossa artifact index was measured for standard-dose DECT, which showed significantly lower values compared with low-dose protocols (p ≤ 0.034). Delineation of ventricular margins and sharpness of subarachnoidal spaces were rated excellent in all protocols (p ≥ 0.096). Low-dose techniques lowered radiation dose by 26% for SECT images (DLP, 575.0 ± 72.3 mGy · cm vs 771.5 ± 146.8 mGy · cm; p dual-source CT while allowing significant radiation dose reduction.

  13. A Component-Minimized Single-Phase Active Power Decoupling Circuit with Reduced Current Stress to Semiconductor Switches

    DEFF Research Database (Denmark)

    Tang, Yi; Blaabjerg, Frede

    2015-01-01

    inductor. With such a configuration, this leg can control the current going into the two output capacitors connected in series for power decoupling, and the other leg can control the line current according to active and reactive power requirement. The proposed topology does not require additional passive...... component, e.g. inductors or film capacitors for ripple energy storage because this task can be accomplished by the dc-link capacitors, and therefore its implementation cost can be minimized. Another unique feature of the proposed topology is that the current stress of power semiconductors can be reduced...

  14. Use of the Maximum Torque Sensor to Reduce the Starting Current in the Induction Motor

    Directory of Open Access Journals (Sweden)

    Muchlas

    2010-03-01

    Full Text Available Use of the maximum torque sensor has been demonstrated able to improve the standard ramp-up technique in the induction motor circuit system. The induction motor used was of a three-phase squirrel-cage motor controlled using a microcontroller 68HC11. From the simulation done, it has been found that this innovative technique could optimize the performance of motor by introducing low stator current and low power consumption over the standard ramp-up technique.

  15. Surgical handover in an era of reduced working hours: an audit of current practice.

    Science.gov (United States)

    Shafiq-ur-Rehman; Mehmood, Sajid; Ahmed, Jamil; Razzaq, Muhammad Haroon; Khan, Shakeeb; Perry, Eugene Phillip

    2012-06-01

    To examine the current practice of handover and to record trainees' assessment of handover process. An audit study. Department of General Surgery, Scarborough General Hospital, Scarborough, United Kingdom, from January to April 2010. A paper-based questionnaire containing instruments pertaining to handover guidelines was disseminated to trainees on surgical on-call rota at the hospital. Trainees' responses regarding handover process including information transferred, designated location, duration, structure, senior supervision, awareness of guidelines, formal training, and rating of current handover practice were analysed. A total of 42 questionnaires were returned (response rate = 100%). The trainees included were; registrars 21% (n=9), core surgical trainees 38 % (n=16), and foundation trainees 41% (n=17). Satisfactory compliance (> 80% handover sessions) to RCS guidelines was observed for only five out of nine components. Ninety-five percent of hand over sessions took place at a designated place and two-third lasted less than 20-minutes. Computer generated handover sheet 57% (n=24) was the most commonly practised method of handover. Specialist registrar 69 % (n=29) remained the supervising person in majority of handover sessions. None of the respondents received formal teaching or training in handover, whereas only half of them 48% (n=20) were aware of handover guidelines. Twenty-one percent of the trainees expressed dissatisfaction with the current practice of handover. Current practice of surgical handover lacks structure despite a fair degree of compliance to RCS handover guidelines. A computerised-sheet based structured handover process, subjected to regular audit, would ensure patient safety and continuity of care.

  16. A review of current strategies to reduce intraoperative bacterial contamination of surgical wounds

    OpenAIRE

    Dohmen, Pascal M.; Konertz, Wolfgang

    2007-01-01

    Surgical site infections are a mean topic in cardiac surgery, leading to a prolonged hospitalization, and substantially increased morbidity and mortality. One source of pathogens is the endogenous flora of the patient?s skin, which can contaminate the surgical site. A number of preoperative skin care strategies are performed to reduce bacterial contamination like preoperative antiseptic showering, hair removal, antisepsis of the skin, adhesive barrier drapes, and antimicrobial prophylaxis. Fu...

  17. The Effect of an Intervention Aimed at Reducing Errors when Administering Medication through Enteral Feeding Tubes in an Institution for Individuals with Intellectual Disability

    Science.gov (United States)

    Idzinga, J. C.; de Jong, A. L.; van den Bemt, P. M. L. A.

    2009-01-01

    Background: Previous studies, both in hospitals and in institutions for clients with an intellectual disability (ID), have shown that medication errors at the administration stage are frequent, especially when medication has to be administered through an enteral feeding tube. In hospitals a specially designed intervention programme has proven to…

  18. Non-destructive controls in the steel tube industry

    International Nuclear Information System (INIS)

    Mondot, J.

    1978-01-01

    The main non-destructive control methods in the tube industry are reviewed: eddy currents, particularly well adapted to small tubes; magnetoscopic testing for weldless tubes; ultrasonic waves widely used for thick weldless tubes and weldings; radiography, to examine tube ends and the known questionable zones; measure of diameters by laser [fr

  19. Is It Better to Enter a Volume CT Dose Index Value before or after Scan Range Adjustment for Radiation Dose Optimization of Pediatric Cardiothoracic CT with Tube Current Modulation?

    Science.gov (United States)

    2018-01-01

    Objective To determine whether the body size-adapted volume computed tomography (CT) dose index (CTDvol) in pediatric cardiothoracic CT with tube current modulation is better to be entered before or after scan range adjustment for radiation dose optimization. Materials and Methods In 83 patients, cardiothoracic CT with tube current modulation was performed with the body size-adapted CTDIvol entered after (group 1, n = 42) or before (group 2, n = 41) scan range adjustment. Patient-related, radiation dose, and image quality parameters were compared and correlated between the two groups. Results The CTDIvol after the CT scan in group 1 was significantly higher than that in group 2 (1.7 ± 0.1 mGy vs. 1.4 ± 0.3 mGy; p Hounsfield units [HU] vs. 4.5 ± 0.7 HU) and image quality (1.5 ± 0.6 vs. 1.5 ± 0.6) showed no significant differences between the two (p > 0.05). In both groups, all patient-related parameters, except body density, showed positive correlations (r = 0.49–0.94; p 0.05) in group 2. Conclusion In pediatric cardiothoracic CT with tube current modulation, the CTDIvol entered before scan range adjustment provides a significant dose reduction (18%) with comparable image quality compared with that entered after scan range adjustment.

  20. The optimal design of 15 nm gate-length junctionless SOI FinFETs for reducing leakage current

    International Nuclear Information System (INIS)

    Liu, Xi; Wu, Meile; Jin, Xiaoshi; Chuai, Rongyan; Lee, Jung-Hee; Lee, Jong-Ho

    2013-01-01

    Junctionless (JL) transistors need to be heavily doped to have large drain current in the ON-state, which engenders the effect of band-to-band tunneling (BTBT) in the OFF-state simultaneously. It causes an obvious increase of the leakage current in the OFF-state. This paper presents an effective method of reducing the leakage current by changing the geometrical shape and dimension of the oxide layer under the edge of the gate. The optimal design of 15 nm gate-length JL silicon-on-insulator FinFETs with the triple-gate structure is performed for reducing the effect of BTBT through simulation and analysis by this means. (paper)

  1. Current trials to reduce surgical intervention in ductal carcinoma in situ of the breast: Critical review.

    Science.gov (United States)

    Toss, M; Miligy, I; Thompson, A M; Khout, H; Green, A R; Ellis, I O; Rakha, E A

    2017-10-01

    The high proportion of ductal carcinoma in situ (DCIS) presented in mammographic screening and the relatively low risk of progression to invasive disease have raised questions related to overtreatment. Following a review of current DCIS management protocols a more conservative approach has been suggested. Clinical trials have been introduced to evaluate the option of avoiding surgical intervention in a proportion of patients with DCIS defined as "low-risk" using certain clinicopathological criteria. These trials can potentially provide evidence-based models of active surveillance (with or without endocrine therapy) as a future management approach. Despite the undisputable fact of our need to address the obvious overtreatment of screen-detected DCIS, some important questions need to be considered regarding these trials including the eligibility criteria and definition of risk, the proportion of patient eligible for inclusion, and the length of time required for proper analysis of the trials' outcome in view of the long-term natural history of DCIS progression particularly the low-risk group. These factors can potentially affect the practicality and future impact of such trials. This review provides critical analysis of current DCIS management trials and highlights critical issues related to their practicality and the expected outcome. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Reduced-Rank Array Modes of the California Current Observing System

    Science.gov (United States)

    Moore, Andrew M.; Arango, Hernan G.; Edwards, Christopher A.

    2018-01-01

    The information content of the ocean observing array spanning the U.S. west coast is explored using the reduced-rank array modes (RAMs) derived from a four-dimensional variational (4D-Var) data assimilation system covering a period of three decades. RAMs are an extension of the original formulation of array modes introduced by Bennett (1985) but in the reduced model state-space explored by the 4D-Var system, and reveal the extent to which this space is activated by the observations. The projection of the RAMs onto the empirical orthogonal functions (EOFs) of the 4D-Var background error correlation matrix provides a quantitative measure of the effectiveness of the measurements in observing the circulation. It is found that much of the space spanned by the background error covariance is unconstrained by the present ocean observing system. The RAM spectrum is also used to introduce a new criterion to prevent 4D-Var from overfitting the model to the observations.

  3. Pituitary adenylate cyclase activating polypeptide reduces A-type K+ currents and caspase activity in cultured adult mouse olfactory neurons.

    Science.gov (United States)

    Han, P; Lucero, M T

    2005-01-01

    Pituitary adenylate cyclase activating polypeptide has been shown to reduce apoptosis in neonatal cerebellar and olfactory receptor neurons, however the underlying mechanisms have not been elucidated. In addition, the neuroprotective effects of pituitary adenylate cyclase activating polypeptide have not been examined in adult tissues. To study the effects of pituitary adenylate cyclase activating polypeptide on neurons in apoptosis, we measured caspase activation in adult olfactory receptor neurons in vitro. Interestingly, we found that the protective effects of pituitary adenylate cyclase activating polypeptide were related to the absence of a 4-aminopyridine (IC50=144 microM) sensitive rapidly inactivating potassium current often referred to as A-type current. In the presence of 40 nM pituitary adenylate cyclase activating polypeptide 38, both A-type current and activated caspases were significantly reduced. A-type current reduction by pituitary adenylate cyclase activating polypeptide was blocked by inhibiting the phospholipase C pathway, but not the adenylyl cyclase pathway. Our observation that 5 mM 4-aminopyridine mimicked the caspase inhibiting effects of pituitary adenylate cyclase activating polypeptide indicates that A-type current is involved in apoptosis. This work contributes to our growing understanding that potassium currents are involved with the activation of caspases to affect the balance between cell life and death.

  4. Transcranial direct current stimulation reduces negative affect but not cigarette craving in overnight abstinent smokers

    Directory of Open Access Journals (Sweden)

    Jiansong eXu

    2013-09-01

    Full Text Available Transcranial direct current stimulation (tDCS can enhance cognitive control functions including attention and top-down regulation over negative affect and substance craving in both healthy and clinical populations, including early abstinent (~1.5 h smokers. The aim of this study was to assess whether tDCS modulates negative affect, cigarette craving, and attention of overnight abstinent tobacco dependent smokers. In this study, 24 smokers received a real and a sham session of tDCS after overnight abstinence from smoking on two different days. We applied anode to the left dorsal lateral prefrontal cortex (DLPFC and cathode to the right supra orbital area for 20min with a current of 2.0mA. We used self-report questionnaires Profile of Mood State (POMS to assess negative affect and Urge to Smoke (UTS Scale to assess craving for cigarette smoking, and a computerized visual target identification task to assess attention immediately before and after each tDCS. Smokers reported significantly greater reductions in POMS scores of total mood disturbance and scores of tension-anxiety, depression-dejection, and confusion-bewilderment subscales after real relative to sham tDCS. Furthermore, this reduction in negative affect positively correlated with the level of nicotine dependence as assessed by Fagerström scale. However, reductions in cigarette craving after real vs. sham tDCS did not differ, nor were there differences in reaction time or hit rate change on the visual task. Smokers did not report significant side effects of tDCS. This study demonstrates the safety of tDCS and its promising effect in ameliorating negative affect in overnight abstinent smokers. Its efficacy in treating tobacco dependence deserves further investigation.

  5. Ear Tubes

    Science.gov (United States)

    ... of the ear drum or eustachian tube, Down Syndrome, cleft palate, and barotrauma (injury to the middle ear caused by a reduction of air pressure, ... specialist) may be warranted if you or your child has experienced repeated ... fluid in the middle ear, barotrauma, or have an anatomic abnormality that ...

  6. Capability evaluation of Eddy current and ultrasonic in-service inspections of steam generator tubes. A status report of PISC III Action 5

    International Nuclear Information System (INIS)

    Bieth, M.; Birac, C.; Comby, R.

    1998-01-01

    Document summarizes the PISC III (Programme for the Inspection of Steel Components) report No. 41, full description of the PISC III Action 5 on Steam Generator Tubes Inspection, containing all details and final conclusions which are still to be approved by the PISC III Management Board. The report was prepared by the reference laboratory of PISC under guidance and with continuous contribution of the members of the Data Analysis Group (DAG) of this PISC III. There were several procedures which demonstrated good detection capability of major flaws in typical locations of the steam generator. Conclusions of the exercise indicate that capability demonstration is necessary to qualify in service inspection procedures for steam generator tubes

  7. Bi-frontal transcranial alternating current stimulation in the ripple range reduced overnight forgetting

    Directory of Open Access Journals (Sweden)

    Géza Gergely eAmbrus

    2015-09-01

    Full Text Available High frequency oscillations in the hippocampal structures recorded during sleep have been proved to be essential for long-term episodic memory consolidation in both animals and in humans. The aim of this study was to test if transcranial Alternating Current Stimulation (tACS of the dorsolateral prefrontal cortex (DLPFC in the hippocampal ripple range, applied bi-frontally during encoding, could modulate declarative memory performance, measured immediately after encoding, and after a night’s sleep. An associative word-pair learning test, taken from Marshall and colleagues, was used. During an evening encoding phase, participants received 1 mA 140 Hz tACS or sham stimulation over both DLPFCs for 10 minutes while being presented twice with a list of word-pairs. Cued recall performance was investigated 10 minutes after training and the morning following the training session. Forgetting from evening to morning was observed in the sham condition, but not in the 140 Hz stimulation condition. 140 Hz tACS during encoding may have an effect on the consolidation of declarative material.

  8. Current Government Actions and Potential Policy Options for Reducing Obesity in Queensland Schools

    Directory of Open Access Journals (Sweden)

    Naser A. Alsharairi

    2018-01-01

    Full Text Available School nutrition policies provide promising avenues towards the improvement of children’s eating habits and the prevention of obesity. Childhood obesity rates and related chronic diseases are increasing in Queensland, in part as a result of unhealthy eating habits and lack of physical activity. There is a very high investment by the Queensland government in maintaining healthy weight and promoting nutrition and physical activity among schoolchildren through delivering a range of initiatives across the state. However, there is a lack of evidence concerning the effectiveness of nutrition/physical education and parental involvement programs addressing obesity delivered in Queensland schools. This paper can be used to guide government and policy-makers regarding the most effective policy options that will promote healthy eating and physical activity among Queensland schoolchildren. The aim of this paper is to: (i summarize current evidence on Queensland government responses to obesity; and (ii discuss potential policy options that could support healthy eating and regular physical activity, and examine the evidence base for each option and suggest new areas for future research.

  9. Reducing the iron burden and improving survival in transfusion-dependent thalassemia patients: current perspectives

    Directory of Open Access Journals (Sweden)

    Bayanzay K

    2016-08-01

    Full Text Available Karim Bayanzay, Lama Alzoebie Department of Hematology, Gulf Medical University, Ajman, United Arab Emirates Abstract: Hypertransfusion regimens for thalassemic patients revolutionized the management of severe thalassemia; transforming a disease which previously led to early infant death into a chronic condition. The devastating effect of the accrued iron from chronic blood transfusions necessitates a more finely tuned approach to limit the complications of the disease, as well as its treatment. A comprehensive approach including carefully tailored transfusion protocol, continuous monitoring and assessment of total body iron levels, and iron chelation are currently the mainstay in treating iron overload. There are also indications for ancillary treatments, such as splenectomy and fetal hemoglobin induction. The main cause of death in iron overload continues to be related to cardiac complications. However, since the widespread use of iron chelation started in the 1970s, there has been a general improvement in survival in these patients. Keywords: hematology, chelators, deferoxamine, deferiserox, deferiprone, liver iron concentration, iron overload, serum ferritin concentration, hepatic iron storage, iron chelation therapy

  10. Bi-frontal transcranial alternating current stimulation in the ripple range reduced overnight forgetting.

    Science.gov (United States)

    Ambrus, Géza Gergely; Pisoni, Alberto; Primaßin, Annika; Turi, Zsolt; Paulus, Walter; Antal, Andrea

    2015-01-01

    High frequency oscillations in the hippocampal structures recorded during sleep have been proved to be essential for long-term episodic memory consolidation in both animals and in humans. The aim of this study was to test if transcranial Alternating Current Stimulation (tACS) of the dorsolateral prefrontal cortex (DLPFC) in the hippocampal ripple range, applied bi-frontally during encoding, could modulate declarative memory performance, measured immediately after encoding, and after a night's sleep. An associative word-pair learning test was used. During an evening encoding phase, participants received 1 mA 140 Hz tACS or sham stimulation over both DLPFCs for 10 min while being presented twice with a list of word-pairs. Cued recall performance was investigated 10 min after training and the morning following the training session. Forgetting from evening to morning was observed in the sham condition, but not in the 140 Hz stimulation condition. 140 Hz tACS during encoding may have an effect on the consolidation of declarative material.

  11. SG tube identification

    International Nuclear Information System (INIS)

    Hoogstraten, P. van

    1994-01-01

    A ''Tracker'' system is described which is designed to identify any tube in a reactor steam generator quickly and safely. Occupational radiation doses to maintenance workers are reduced by using a Tracker and emergency down times are shortened. The system employs a television camera and light source in a stainless steel box with a large window. Both the camera and spotlight can be panned and tilted to reach any point on the tubesheet and are remotely controlled. An operator at a safe working distance can identify any tube visible on a real time video by comparison with the tubesheet pattern stored earlier in the computer memory. The identified tube can then be spotlighted and dealt with quickly by a maintenance worker inside the channel head. (UK)

  12. Technique employed to seal a tube leaking in a heat exchanger of the tube type by explosives with supporting means for the adjacent tubes

    International Nuclear Information System (INIS)

    Larson, G.C.

    1978-01-01

    This invention concerns the technique employed to seal a tube leaking in a heat exchanger of the tube and tube plate type by detonating metal plugs activated by an explosive and inserted in both ends of the tube. It refers in particular to an apparatus and process in which the deformation or distortion of the adjacent tubes and tube plate ties under the effect of the explosive forces is significantly reduced [fr

  13. Current status of programmes to measure and reduce radon exposure in Irish workplaces

    International Nuclear Information System (INIS)

    Colgan, P A; Madden, J S; Synnott, H; Fennell, S; Pollard, D; Fenton, D

    2004-01-01

    National legislation, which implements European Council Directive 96/29/EURATOM in Ireland, sets a reference level of 400 Bq m -3 averaged over any 3 month period for radon exposure in the workplace and also empowers the Radiological Protection Institute of Ireland to direct employers to have radon measurements carried out. This legislation came into effect in May 2000. Radon measurements have already been completed in show caves and other underground workplaces. Between 1998 and 2001, over 33 800 individual radon measurements were carried out in all ground floor offices and classrooms in 3444 schools nationwide as part of a programme undertaken jointly with the Department of Education and Science. Where the average indoor radon concentration in one or more rooms exceeded 200 Bq m -3 , remedial measures were implemented. For concentrations up to 400 Bq m -3 this involved increased ventilation while for higher concentrations an active sump was normally installed. The results of the survey, as well as the effectiveness of the different remedial strategies, are discussed. In the case of other above ground workplaces, different approaches have been adopted. As a first step, workplaces in two known high radon areas were directed to have radon measurements carried out. This programme had limited success because of problems in obtaining accurate workplace databases and a general lack of awareness on the part of employers of the issues involved. From a sample of 2610 employers directed to measure radon, only 408 actually completed measurements and 37 workplaces were identified as having average 3 month average radon concentrations above 400 Bq m -3 . A total of 1356 employers ignored all correspondence, some of which was sent by registered post and signed for on receipt. Current initiatives are focused on the provision of information and include newspaper advertising as well as publications aimed specifically at both employer and employee representative groups. The ability

  14. Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives.

    Science.gov (United States)

    Baracco, Bruno; Fuentes, M Victoria; Garrido, Miguel A; González-López, Santiago; Ceballos, Laura

    2013-07-01

    The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24 h and 5,000 thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers' instructions. Composite buildups were constructed and the bonded teeth were then stored in water (24 h, 37 °C) or thermocycled (5,000 cycles) before being sectioned and submitted to MTBS test. Two-way ANOVA and subsequent comparison tests were applied at α = 0.05. Characteristic de-bonded specimens were analyzed using scanning electron microscopy (SEM). After 24 h water storage, MTBS values were highest with XP Bond, Adper Scotchbond 1 XT, Filtek Silorane Adhesive System and Adper Scotchbond SE and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. After thermocycling, MTBS values were highest with XP Bond, followed by Filtek Silorane Adhesive System, Adper Scotchbond SE and Adper Scotchbond 1 XT and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. Thermal aging induced a significant decrease in MTBS values with all adhesives tested. The resistance of resin-dentin bonds to thermal-aging degradation was material dependent. One-step self-etch adhesives obtained the lowest MTBS results after both aging treatments, and their adhesive capacity was significantly reduced after thermocycling.

  15. Current status of reduced-activation ferritic/martensitic steels R and D for fusion energy

    International Nuclear Information System (INIS)

    Kimura, Akihiko

    2005-01-01

    Reduced-activation ferritic/martensitic (RAF/M) steels have been considered to be the prime candidate for the fusion blanket structural material. The irradiation data obtained up to now indicates rather high feasibility of the steels for application to fusion reactors because of their high resistance to degradation of material performance caused by both the irradiation-induced displacement damage and transmutation helium atoms. The martensitic structure of RAF/M steels consists of a large number of lattice defects before the irradiation, which strongly retards the formation of displacement damage through absorption and annihilation of the point defects generated by irradiation. Transmutation helium can be also trapped at those defects in the martensitic structure so that the growth of helium bubbles at grain boundaries is suppressed. The major properties of the steels are well within our knowledge, and processing technologies are mostly developed for fusion application. RAF/M steels are now certainly ready to proceed to the next stage, that is, the construction of International Thermo-nuclear Experimental Reactor Test Blanket Modules (ITER-TBM). Oxide dispersion strengthening (ODS) steels have been developed for higher thermal efficiency of fusion power plants. Recent irradiation experiments indicated that the steels were quite highly resistant to neutron irradiation embrittlement, showing hardening accompanied by no loss of ductility. High-Cr ODS steels whose chromium concentration was in the range from 14 to 19 mass% showed high resistance to corrosion in supercritical pressurized water. It is shown that the 14Cr-ODS steel is susceptible to neither hydrogen nor helium embrittlement. A combined utilization of ODS steels with RAF/M steels will be effective to realize fusion power early at a reasonable thermal efficiency. (author)

  16. Novel MSVPWM to reduce the inductor current ripple for Z-source inverter in electric vehicle applications.

    Science.gov (United States)

    Zhang, Qianfan; Dong, Shuai; Xue, Ping; Zhou, Chaowei; Cheng, ShuKang

    2014-01-01

    A novel modified space vector pulse width modulation (MSVPWM) strategy for Z-Source inverter is presented. By rearranging the position of shoot-through states, the frequency of inductor current ripple is kept constant. Compared with existing MSVPWM strategies, the proposed approach can reduce the maximum inductor current ripple. So the volume of Z-source network inductor can be designed smaller, which brings the beneficial effect on the miniaturization of the electric vehicle controller. Theoretical findings in the novel MSVPWM for Z-Source inverter have been verified by experiment results.

  17. Improving the calandria tubes for CANDU reactors

    International Nuclear Information System (INIS)

    Coleman, C.E.; Fong, R.W.L.; Doubt, G.L.

    1997-01-01

    CANDU calandria tubes are made from annealed Zircaloy-2 sheet formed into a cylinder and welded along its length to make the tube. The current calandria tubes have given exemplary service for many years. With more stringent regulations and the need to accommodate warm cooling water in tropical countries, we started a development program to increase the margins for failure during postulated accidents. These improvements involve increasing the tube strength and optimising the heat-transfer from an excessively hot fuel channel to the cool moderator. If the postulated accident involves a pressure tube break, it would be desirable if the calandria tube withstood the full pressure of the heat-transport system. The weakest link in current calandria tubes is the weld. Thickening the weld can increase the strength by 20% while seamless tubes can be 45% stronger than current tubes. The latter tubes can hold full system pressure for many hours without failure. If during the postulated accident the fuel and pressure tube become excessively hot but do not touch the calandria tube, the radiant heat loss must be maximised. Current calandria tubes have an absorptivity (emissivity) of about 0.2. To protect the fuel and the fuel channel we have devised a finish to the inside surface of the calandria tube that increases the emissivity to 0.7. If during the postulated accident the hot pressure tube touches the cool calandria tube, the contact conductance and the critical heat flux must be optimised to ensure nucleate boiling of the moderator at the outside surface of the calandria tube and therefore efficient exploitation of the moderator as a heat sink. In laboratory tests small ridges on the inside surface and roughening of the outside surface have been shown to increase the margins against failure and increase the possible moderator temperatures thus providing the opportunity to decrease the cost of the moderator heat-exchange system and remove restrictions on reactor operation in

  18. Current status of programmes to measure and reduce radon exposure in Irish workplaces

    Energy Technology Data Exchange (ETDEWEB)

    Colgan, P A; Madden, J S; Synnott, H; Fennell, S; Pollard, D; Fenton, D [Radiological Protection Institute of Ireland, 3 Clonskeagh Square, Dublin 14(Ireland)

    2004-06-01

    National legislation, which implements European Council Directive 96/29/EURATOM in Ireland, sets a reference level of 400 Bq m{sup -3} averaged over any 3 month period for radon exposure in the workplace and also empowers the Radiological Protection Institute of Ireland to direct employers to have radon measurements carried out. This legislation came into effect in May 2000. Radon measurements have already been completed in show caves and other underground workplaces. Between 1998 and 2001, over 33 800 individual radon measurements were carried out in all ground floor offices and classrooms in 3444 schools nationwide as part of a programme undertaken jointly with the Department of Education and Science. Where the average indoor radon concentration in one or more rooms exceeded 200 Bq m{sup -3}, remedial measures were implemented. For concentrations up to 400 Bq m{sup -3} this involved increased ventilation while for higher concentrations an active sump was normally installed. The results of the survey, as well as the effectiveness of the different remedial strategies, are discussed. In the case of other above ground workplaces, different approaches have been adopted. As a first step, workplaces in two known high radon areas were directed to have radon measurements carried out. This programme had limited success because of problems in obtaining accurate workplace databases and a general lack of awareness on the part of employers of the issues involved. From a sample of 2610 employers directed to measure radon, only 408 actually completed measurements and 37 workplaces were identified as having average 3 month average radon concentrations above 400 Bq m{sup -3}. A total of 1356 employers ignored all correspondence, some of which was sent by registered post and signed for on receipt. Current initiatives are focused on the provision of information and include newspaper advertising as well as publications aimed specifically at both employer and employee representative

  19. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... and Aging Program African American Program Training and Jobs Fellowships NEI Summer Intern Program Diversity In Vision ... DIVRO) Student Training Programs To search for current job openings visit HHS USAJobs Home >> NEI YouTube Videos >> ...

  20. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Disease Education Program Glaucoma Education Program Low Vision Education Program Hispanic/Latino ... To search for current job openings visit HHS USAJobs Home » NEI YouTube ...

  1. Space Vector Modulation Technique to Reduce Leakage Current of a Transformerless Three-Phase Four-Leg Photovoltaic System

    Directory of Open Access Journals (Sweden)

    F. Hasanzad

    2017-06-01

    Full Text Available Photovoltaic systems integrated to the grid have received considerable attention around the world. They can be connected to the electrical grid via galvanic isolation (transformer or without it (transformerless. Despite making galvanic isolation, low frequency transformer increases size, cost and losses. On the other hand, transformerless PV systems increase the leakage current (common-mode current, (CMC through the parasitic capacitors of the PV array. Inverter topology and switching technique are the most important parameters the leakage current depends on. As there is no need to extra hardware for switching scheme modification, it's an economical method for reducing leakage current. This paper evaluates the effect of different space vector modulation techniques on leakage current for a two-level three-phase four-leg inverter used in PV system. It proposes an efficient space vector modulation method which decreases the leakage current to below the quantity specified in VDE-0126-1-1 standard. furthermore, some other characteristics of the space vector modulation schemes that have not been significantly discussed for four-leg inverter, are considered, such as, modulation index, switching actions per period, common-mode voltage (CMV, and total harmonic distortion (THD. An extend software simulation using MATLAB/Simulink is performed to verify the effectiveness of the modulation technique.

  2. Electron tube

    Science.gov (United States)

    Suyama, Motohiro [Hamamatsu, JP; Fukasawa, Atsuhito [Hamamatsu, JP; Arisaka, Katsushi [Los Angeles, CA; Wang, Hanguo [North Hills, CA

    2011-12-20

    An electron tube of the present invention includes: a vacuum vessel including a face plate portion made of synthetic silica and having a surface on which a photoelectric surface is provided, a stem portion arranged facing the photoelectric surface and made of synthetic silica, and a side tube portion having one end connected to the face plate portion and the other end connected to the stem portion and made of synthetic silica; a projection portion arranged in the vacuum vessel, extending from the stem portion toward the photoelectric surface, and made of synthetic silica; and an electron detector arranged on the projection portion, for detecting electrons from the photoelectric surface, and made of silicon.

  3. The Way of Reducing Current Values in Optical Ground Wires at Asymmetrical Faults on Overhead Transmission Lines

    Directory of Open Access Journals (Sweden)

    Egamnazarov Georgiy

    2016-12-01

    Full Text Available Given the fact that the installing costs of an optical ground wire on overhead lines directly depend on its cross-section, which in turn depends on the level of fault current it should withstand, in order to reduce these current values in the optical ground wire, I suggested performing its isolated descents from the end towers of the line with its transition to an optical cable. The research was carried out on the example of a 500 kV overhead line in the National Electric Power Grid. The Method of Symmetrical Components for calculating asymmetrical fault currents was not used; therefore, calculations were carried out on the base of presenting the line as a multi-wire system for the considered case as a five-wire system (optical ground wire, steel ground wire, and three phase wires. Such approach allows taking into account the initial asymmetry of the line parameters and modeling any kind of asymmetrical faults. The analyses of calculated results were performed. The conclusive evidence that the optical ground wire isolated descents from the end towers of the line give the possibility of reducing the level of maximal fault current distribution values in it and therefore its cross section, is presented.

  4. Chest tube insertion

    Science.gov (United States)

    Chest drainage tube insertion; Insertion of tube into chest; Tube thoracostomy; Pericardial drain ... Be careful there are no kinks in your tube. The drainage system should always sit upright and be placed ...

  5. Comments about the use of a Zig-Zag transformer to reduce the neutral current created by unbalanced nonlinear loads

    International Nuclear Information System (INIS)

    Beverly, L.; Hance, R.; Kristalinski, A.; Visser, A.

    1993-09-01

    The subject of AC line currents with high harmonic content and the potential for overloaded neutral wires caused by the non-linear loading of electronic power supplies has become one of the most popular and at the same time a very complex topic among electrical engineers. Different solutions are offered for this problem. Some examples are specially designed K-rated AC distribution transformers, delta connected primary windings, and L-C tuned filters. All of the above methods have some limitations. For instance, a K-rated transformer does not eliminate harmonics, but transmits them into the feeder. Neutral currents that flow from various loads to the K-rated transformer are still very high. These K-rated transformers are more expensive and are larger in physical size than conventional transformers. The delta connected primary of a power distribution transformer can only eliminate triplen harmonics for balanced loads. Neutral currents caused by the loads are not eliminated. The primary side circuit breaker may also not protect a transformer against overcurrents because the circuit breaker will not see the triplen harmonic current that is circulating in the primary of the transformer. L-C filters can create undesirable resonances, which will lead to an increase in harmonic currents. Another solution is to use a number of small Zig-Zag transformers to reduce the neutral current. This is attractive for the following reasons: relatively low cost, simplicity, ease of installation on existing distribution systems, ability to keep neutral currents local thus eliminating the need for larger neutral wires, and the ability to improve the fundamental load current balance as well

  6. Focal spot size reduction using asymmetric collimation to enable reduced anode angles with a conventional angiographic x-ray tube for use with high resolution detectors

    Science.gov (United States)

    Russ, M.; Shankar, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Bednarek, D. R.; Rudin, S.

    2017-03-01

    The high-resolution requirements for neuro-endovascular image-guided interventions (EIGIs) necessitate the use of a small focal-spot size; however, the maximum tube output limits for such small focal-spot sizes may not enable sufficient x-ray fluence after attenuation through the human head to support the desired image quality. This may necessitate the use of a larger focal spot, thus contributing to the overall reduction in resolution. A method for creating a higher-output small effective focal spot based on the line-focus principle has been demonstrated and characterized. By tilting the C-arm gantry, the anode-side of the x-ray field-of-view is accessible using a detector placed off-axis. This tilted central axis diminishes the resultant focal spot size in the anode-cathode direction by the tangent of the effective anode angle, allowing a medium focal spot to be used in place of a small focal spot with minimal losses in resolution but with increased tube output. Images were acquired of two different objects at the central axis, and with the C-arm tilted away from the central axis at 1° increments from 0°-7°. With standard collimation settings, only 6° was accessible, but using asymmetric extended collimation a maximum of 7° was accessed for enhanced comparisons. All objects were positioned perpendicular to the anode-cathode direction and images were compared qualitatively. The increasing advantage of the off-axis focal spots was quantitatively evidenced at each subsequent angle using the Generalized Measured-Relative Object Detectability metric (GM-ROD). This anode-tilt method is a simple and robust way of increasing tube output for a small field-of-view detector without diminishing the overall apparent resolution for neuro-EIGIs.

  7. Impact and appreciation of two methods aiming at reducing hazardous drug environmental contamination: The centralization of the priming of IV tubing in the pharmacy and use of a closed-system transfer device.

    Science.gov (United States)

    Guillemette, Annie; Langlois, Hélène; Voisine, Maxime; Merger, Delphine; Therrien, Roxane; Mercier, Genevieve; Lebel, Denis; Bussières, Jean-François

    2014-12-01

    The main objective was to evaluate the impact of two methods aiming at reducing hazardous drug environmental contamination: the centralization of the priming of IV tubing in the pharmacy and the use of a closed-system transfer device. The secondary objective was to evaluate the satisfaction of pharmacy technicians using a survey. Sites in the hematology-oncology satellite pharmacy and care unit were analyzed for the presence of cyclophosphamide, ifosfamide and methotrexate before and after the centralization of the priming of IV tubing in the pharmacy and before and after using a closed-system transfer device. The limits of detection for cyclophosphamide, ifosfamide and methotrexate were, respectively, of 0.0015 ng/cm(2), 0.0012 ng/cm(2) and 0.0060 ng/cm(2). The pharmacy technician satisfaction was evaluated using a questionnaire. A total of 225 samples was quantified. After the centralization of priming in the pharmacy, no significant difference was found in the proportion of positive samples for cyclophosphamide, ifosfamide and methotrexate. Traces of cyclophosphamide found on the floor in patient care areas was significantly reduced (median[min-max] 0.08[0.06-0.09]ng/cm(2) vs. 0.03[0.02-0.05], p tubing in the pharmacy reduced floor contamination in patient care areas without increasing surface contamination in the pharmacy. Closed-system transfer devices reduced contamination in pharmacy, but handling issues were raised by pharmacy technicians. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  8. Models for Automated Tube Performance Calculations

    International Nuclear Information System (INIS)

    Brunkhorst, C.

    2002-01-01

    High power radio-frequency systems, as typically used in fusion research devices, utilize vacuum tubes. Evaluation of vacuum tube performance involves data taken from tube operating curves. The acquisition of data from such graphical sources is a tedious process. A simple modeling method is presented that will provide values of tube currents for a given set of element voltages. These models may be used as subroutines in iterative solutions of amplifier operating conditions for a specific loading impedance

  9. Operating performance of CANDU pressure tubes

    International Nuclear Information System (INIS)

    Cheadle, B.A.; Price, E.G.

    1989-04-01

    The performance of Zircaloy-2 and Zr-2.5 Nb pressure tubes in CANDU reactors is reviewed. The accelerated hydriding of Zircaloy-2 in reducing water chemistries can lower the toughness of this material and it is essential that defect-initiating phenomena, such as hydride blister formation from pressure tube to calandria tube contact, be prevented. Zr-2.5 Nb pressure tubes are performing well with low rates of hydrogen pick-up and good retention of material properties

  10. Jose Cabrera (Zorita) tube examination

    International Nuclear Information System (INIS)

    Kuchirka, P.J.

    1986-01-01

    Jose Cabrera (Zorita) tube examination procedures are discussed. This plant continues to use phosphate water chemistry (sodium/phosphate ratio = 2.1). Three hot leg tube segments were pulled from the Jose Cabera (Zorita) plant in 1985. One tube had a field EC indication on the OD at the first tube support plate and the other two had field EC indications on their ID about 3 inches above the bottom of the tube sheet. All three tubes were initially sent to Battelle for preliminary NDE and decontamination. Segments of two tubes were sent to Westinghouse for destructive examination. The results of the laboratory eddy current and radiographic examinations are given. The results of the visual examinations are also given. The tube with OD indications was destructively examined and shallow intergranular pitting and intergranular attack, up to 2 mils deep, were found on the OD in the tube sheet region. Local areas of IGA, up to 5 mils deep, were found on the OD within the tube support plate region. A summary of this information together with supporting micrographs is given. It was hypothesized that a caustic crevice environment was the cause of this mild degradation. Shallow areas of thinning or wastage, up to 3 mils, were found just above the top of the tube sheet in the sludge pile region. Even more shallow wastage was found at the edges of support plate locations. This wastage is believed to be the remnant of early plant chemistry when a higher sodium/phosphate ratio and higher phosphate concentration were allowed

  11. Use of a Y-tube conduit after facial nerve injury reduces collateral axonal branching at the lesion site but neither reduces polyinnervation of motor endplates nor improves functional recovery.

    Science.gov (United States)

    Hizay, Arzu; Ozsoy, Umut; Demirel, Bahadir Murat; Ozsoy, Ozlem; Angelova, Srebrina K; Ankerne, Janina; Sarikcioglu, Sureyya Bilmen; Dunlop, Sarah A; Angelov, Doychin N; Sarikcioglu, Levent

    2012-06-01

    Despite increased understanding of peripheral nerve regeneration, functional recovery after surgical repair remains disappointing. A major contributing factor is the extensive collateral branching at the lesion site, which leads to inaccurate axonal navigation and aberrant reinnervation of targets. To determine whether the Y tube reconstruction improved axonal regrowth and whether this was associated with improved function. We used a Y-tube conduit with the aim of improving navigation of regenerating axons after facial nerve transection in rats. Retrograde labeling from the zygomatic and buccal branches showed a halving in the number of double-labeled facial motor neurons (15% vs 8%; P facial-facial anastomosis coaptation. However, in both surgical groups, the proportion of polyinnervated motor endplates was similar (≈ 30%; P > .05), and video-based motion analysis of whisking revealed similarly poor function. Although Y-tube reconstruction decreases axonal branching at the lesion site and improves axonal navigation compared with facial-facial anastomosis coaptation, it fails to promote monoinnervation of motor endplates and confers no functional benefit.

  12. Application of Barcoding to Reduce Error of Patient Identification and to Increase Patient's Information Confidentiality of Test Tube Labelling in a Psychiatric Teaching Hospital.

    Science.gov (United States)

    Liu, Hsiu-Chu; Li, Hsing; Chang, Hsin-Fei; Lu, Mei-Rou; Chen, Feng-Chuan

    2015-01-01

    Learning from the experience of another medical center in Taiwan, Kaohsiung Municipal Kai-Suan Psychiatric Hospital has changed the nursing informatics system step by step in the past year and a half . We considered ethics in the original idea of implementing barcodes on the test tube labels to process the identification of the psychiatric patients. The main aims of this project are to maintain the confidential information and to transport the sample effectively. The primary nurses had been using different work sheets for this project to ensure the acceptance of the new barcode system. In the past two years the errors in the blood testing process were as high as 11,000 in 14,000 events per year, resulting in wastage of resources. The actions taken by the nurses and the new barcode system implementation can improve the clinical nursing care quality, safety of the patients, and efficiency, while decreasing the cost due to the human error.

  13. Reduced harm or another gateway to smoking? source, message, and information characteristics of E-cigarette videos on YouTube.

    Science.gov (United States)

    Paek, Hye-Jin; Kim, Sookyong; Hove, Thomas; Huh, Jung Yoon

    2014-01-01

    E-cigarettes are widely promoted on the Internet, but little is known about what kinds of information about them are available online. This study examines message, source, and health information characteristics of e-cigarette videos on the popular online video-sharing platform YouTube. A content analysis of 365 e-cigarette videos indicates that 85% of the videos were sponsored by marketers. These videos highlight e-cigarettes' economic and social benefits, featuring a low level of fear appeal and negative message valence and a high level of marketing information about e-cigarette products. They also convey certain health claims that have been proscribed by the U.S. Food and Drug Administration, the prevalence of which warrants ongoing monitoring and regulatory guidelines for online e-cigarette marketing.

  14. Cladding tube manufacturing technology

    International Nuclear Information System (INIS)

    Hahn, R.; Jeong, Y. H.; Baek, B. J.; Kim, K. H.; Kim, S. J.; Choi, B. K.; Kim, J. M.

    1999-04-01

    This report gives an overview of the manufacturing routine of PWR cladding tubes. The routine essentially consists of a series of deformation and annealing processes which are necessary to transform the ingot geometry to tube dimensions. By changing shape, microstructure and structure-related properties are altered simultaneously. First, a short overview of the basics of that part of deformation geometry is given which is related to tube reducing operations. Then those processes of the manufacturing routine which change the microstructure are depicted, and the influence of certain process parameters on microstructure and material properties are shown. The influence of the resulting microstructure on material properties is not discussed in detail, since it is described in my previous report A lloy Development for High Burnup Cladding . Because of their paramount importance still up to now, and because manufacturing data and their influence on properties for other alloys are not so well established or published, the descriptions are mostly related to Zry4 tube manufacturing, and are only in short for other alloys. (author). 9 refs., 46 figs

  15. Cladding tube manufacturing technology

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, R. [Kraftwerk Union AG, Mulheim (Germany); Jeong, Y.H.; Baek, B.J.; Kim, K.H.; Kim, S.J.; Choi, B.K.; Kim, J.M. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1999-04-01

    This report gives an overview of the manufacturing routine of PWR cladding tubes. The routine essentially consists of a series of deformation and annealing processes which are necessary to transform the ingot geometry to tube dimensions. By changing shape, microstructure and structure-related properties are altered simultaneously. First, a short overview of the basics of that part of deformation geometry is given which is related to tube reducing operations. Then those processes of the manufacturing routine which change the microstructure are depicted, and the influence of certain process parameters on microstructure and material properties are shown. The influence of the resulting microstructure on material properties is not discussed in detail, since it is described in my previous report 'Alloy Development for High Burnup Cladding.' Because of their paramount importance still up to now, and because manufacturing data and their influence on properties for other alloys are not so well established or published, the descriptions are mostly related to Zry4 tube manufacturing, and are only in short for other alloys. (author). 9 refs., 46 figs.

  16. Tube Plugging Criteria for the High-pressure Heaters of Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungnam; Cho, Nam-Cheoul; Lee, Kuk-hee [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In this paper, a method to establish the tube plugging criteria of BOP heat exchangers is introduced and the tube plugging criteria for the high pressure heaters of a nuclear power plant. This method relies on the similar plugging criteria used in the steam generator tubes. Power generation field urges nuclear power plants to reduce operating and maintaining costs to remain competitive. To reduce the cost by means of preventing the lowering thermal efficiency, the inspection of balance-of-plant heat exchanger, which was treated as not important work, becomes important. The tubing materials and tube thickness of heat exchangers in nuclear power plants are selected to withstand system temperature, pressure, and corrosion. But tubes have experienced leaks and failures and plugged based upon eddy current testing (ET) results. There are some problems for plugging the heat exchanger tubes since the criterion and its basis are not clearly described. For this reason, the criteria for the tube wall thickness are addressed in order to operate the heat exchangers in nuclear power plant without trouble during the cycle. The feed water heater is a kind of heat exchanger which raises the temperature of water supplied from the condenser. The heat source of high-pressure heaters is the extraction steam from the high-pressure turbine and moisture separator re-heater. If the tube wall of the heater is broken, the feed water flowing inside the tube intrudes to shell side. This forces the turbine to be stop in order to protect it. There are many codes and standards to be referred for calculating the minimum thickness of the heat exchanger tube in the designing stage. However, the codes and standards related to show the tube plugging criteria may not exist currently. A method to establish the tube plugging criteria of BOP heat exchangers is introduced and the tube plugging criteria for the high pressure heaters of Ulchin NPP No. 3 and 4. This method relies on the similar plugging

  17. Patient identification and tube labelling

    DEFF Research Database (Denmark)

    van Dongen-Lases, Edmée C; Cornes, Michael P; Grankvist, Kjell

    2016-01-01

    of phlebotomy procedures with the CLSI H3-A6 guideline was unacceptably low, and that patient identification and tube labelling are amongst the most critical steps in need of immediate attention and improvement. The process of patient identification and tube labelling is an essential safety barrier to prevent...... patient identity mix-up. Therefore, the EFLM Working Group aims to encourage and support worldwide harmonisation of patient identification and tube labelling procedures in order to reduce the risk of preanalytical errors and improve patient safety. With this Position paper we wish to raise awareness...... and provide recommendations for proper patient and sample identification procedures....

  18. Hydroxychloroquine reduces heart rate by modulating the hyperpolarization-activated current If: Novel electrophysiological insights and therapeutic potential

    Science.gov (United States)

    Capel, Rebecca A.; Herring, Neil; Kalla, Manish; Yavari, Arash; Mirams, Gary R.; Douglas, Gillian; Bub, Gil; Channon, Keith; Paterson, David J.; Terrar, Derek A.; Burton, Rebecca-Ann B.

    2015-01-01

    Background Bradycardic agents are of interest for the treatment of ischemic heart disease and heart failure, as heart rate is an important determinant of myocardial oxygen consumption. Objectives The purpose of this study was to investigate the propensity of hydroxychloroquine (HCQ) to cause bradycardia. Methods We assessed the effects of HCQ on (1) cardiac beating rate in vitro (mice); (2) the “funny” current (If) in isolated guinea pig sinoatrial node (SAN) myocytes (1, 3, 10 µM); (3) heart rate and blood pressure in vivo by acute bolus injection (rat, dose range 1–30 mg/kg), (4) blood pressure and ventricular function during feeding (mouse, 100 mg/kg/d for 2 wk, tail cuff plethysmography, anesthetized echocardiography). Results In mouse atria, spontaneous beating rate was significantly (P < .05) reduced (by 9% ± 3% and 15% ± 2% at 3 and 10 µM HCQ, n = 7). In guinea pig isolated SAN cells, HCQ conferred a significant reduction in spontaneous action potential firing rate (17% ± 6%, 1 μM dose) and a dose-dependent reduction in If (13% ± 3% at 1 µM; 19% ± 2% at 3 µM). Effects were also observed on L-type calcium ion current (ICaL) (12% ± 4% reduction) and rapid delayed rectifier potassium current (IKr) (35% ± 4%) at 3 µM. Intravenous HCQ decreased heart rate in anesthetized rats (14.3% ± 1.1% at 15mg/kg; n = 6) without significantly reducing mean arterial blood pressure. In vivo feeding studies in mice showed no significant change in systolic blood pressure nor left ventricular function. Conclusions We have shown that HCQ acts as a bradycardic agent in SAN cells, in atrial preparations, and in vivo. HCQ slows the rate of spontaneous action potential firing in the SAN through multichannel inhibition, including that of If. PMID:26025323

  19. Reduced translocation of current photosynthate precedes changes in gas exchange for Quercus rubra seedlings under flooding stress.

    Science.gov (United States)

    Sloan, Joshua L; Islam, M Anisul; Jacobs, Douglass F

    2016-01-01

    Northern red oak (Quercus rubra L.) seedlings are frequently planted on suboptimal sites in their native range in North America, subjecting them to environmental stresses, such as flooding, for which they may not be well adapted. Members of the genus Quercus exhibit a wide range of responses to flooding, and responses of northern red oak to flooding remain inadequately described. To better understand the physiological effects of root system inundation in post-transplant northern red oak seedlings and the effects of flooding on endogenous patterns of resource allocation within the plant, we observed the effects of short-term flooding initiated at the linear shoot growth stage on net photosynthetic rates, dark respiration, chlorophyll fluorescence (Fv/Fm) and translocation of (13)C-labeled current photosynthate. Downward translocation of current photosynthate declined after 4 days of flooding and was the first measured physiological response to flooding; net photosynthetic rates decreased and dark respiration rates increased after 7 days of flooding. Short-term flooding did not affect maximal potential efficiency of photosystem II (Fv/Fm). The finding that decreased downward translocation of (13)C-labeled current photosynthate preceded reduced net photosynthesis and increased dark respiration during flooding suggests the occurrence of sink-limited photosynthesis under these conditions. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Intra-individual diagnostic image quality and organ-specific-radiation dose comparison between spiral cCT with iterative image reconstruction and z-axis automated tube current modulation and sequential cCT

    International Nuclear Information System (INIS)

    Wenz, Holger; Maros, Máté E.; Meyer, Mathias; Gawlitza, Joshua; Förster, Alex; Haubenreisser, Holger; Kurth, Stefan; Schoenberg, Stefan O.; Groden, Christoph; Henzler, Thomas

    2016-01-01

    •Superiority of spiral versus sequential cCT in image quality and organ-specific-radiation dose.•Spiral cCT: lower organ-specific-radiation-dose in eye lense compared to tilted sequential cCT.•State-of-the-art IR spiral cCT techniques has significant advantages over sequential cCT techniques. Superiority of spiral versus sequential cCT in image quality and organ-specific-radiation dose. Spiral cCT: lower organ-specific-radiation-dose in eye lense compared to tilted sequential cCT. State-of-the-art IR spiral cCT techniques has significant advantages over sequential cCT techniques. To prospectively evaluate image quality and organ-specific-radiation dose of spiral cranial CT (cCT) combined with automated tube current modulation (ATCM) and iterative image reconstruction (IR) in comparison to sequential tilted cCT reconstructed with filtered back projection (FBP) without ATCM. 31 patients with a previous performed tilted non-contrast enhanced sequential cCT aquisition on a 4-slice CT system with only FBP reconstruction and no ATCM were prospectively enrolled in this study for a clinical indicated cCT scan. All spiral cCT examinations were performed on a 3rd generation dual-source CT system using ATCM in z-axis direction. Images were reconstructed using both, FBP and IR (level 1–5). A Monte-Carlo-simulation-based analysis was used to compare organ-specific-radiation dose. Subjective image quality for various anatomic structures was evaluated using a 4-point Likert-scale and objective image quality was evaluated by comparing signal-to-noise ratios (SNR). Spiral cCT led to a significantly lower (p < 0.05) organ-specific-radiation dose in all targets including eye lense. Subjective image quality of spiral cCT datasets with an IR reconstruction level 5 was rated significantly higher compared to the sequential cCT acquisitions (p < 0.0001). Consecutive mean SNR was significantly higher in all spiral datasets (FBP, IR 1–5) when compared to sequential cCT with a mean

  1. Ultra High Power and Efficiency Space Traveling-Wave Tube Amplifier Power Combiner with Reduced Size and Mass for NASA Missions

    Science.gov (United States)

    Simons, Rainee N.; Wintucky, Edwin G.; Wilson, Jeffrey D.; Force, Dale A.

    2009-01-01

    In the 2008 International Microwave Symposium (IMS) Digest version of our paper, recent advances in high power and efficiency space traveling-wave tube amplifiers (TWTAs) for NASA s space-to-Earth communications are presented. The RF power and efficiency of a new K-Band amplifier are 40 W and 50 percent and that of a new Ka-Band amplifier are 200 W and 60 percent. An important figure-of-merit, which is defined as the ratio of the RF power output to the mass (W/kg) of a TWT, has improved by a factor of ten over the previous generation Ka-Band devices. In this extended paper, a high power, high efficiency Ka-band combiner for multiple TWTs, based on a novel hybrid magic-T waveguide circuit design, is presented. The measured combiner efficiency is as high as 90 percent. In addition, at the design frequency of 32.05 GHz, error-free uncoded BPSK/QPSK data transmission at 8 megabits per second (Mbps), which is typical for deep space communications is demonstrated. Furthermore, QPSK data transmission at 622 Mbps is demonstrated with a low bit error rate of 2.4x10(exp -8), which exceeds the deep space state-of-the-art data rate transmission capability by more than two orders of magnitude. A potential application of the TWT combiner is in deep space communication systems for planetary exploration requiring transmitter power on the order of a kilowatt or higher.

  2. Steam generator tube performance: world experience with water-cooled nuclear power reactors during 1979

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1981-01-01

    The performance of steam generator tubes in water-cooled nuclear power reactors is reviewed for 1979. Tube failures occurred at 38 of the 93 reactors surveyed. The causes of these failures and the procedures designed to deal with them are described. The defect rate, although higher than that in 1978, was still lower than the rates of the two previous years. Methods being employed to detect defects include the increased use of multifrequency eddy-current testing and a trend to full-length inspection of all tubes. To reduce the incidence of tube failure by corrosion, plant operators are turning to full-flow condensate demineralization and more leak-resistant condenser tubes. 10 tables

  3. Reduced density and altered regulation of rat atrial L-type Ca2+ current in heart failure.

    Science.gov (United States)

    Bond, Richard C; Bryant, Simon M; Watson, Judy J; Hancox, Jules C; Orchard, Clive H; James, Andrew F

    2017-03-01

    Constitutive regulation by PKA has recently been shown to contribute to L-type Ca 2+ current ( I CaL ) at the ventricular t-tubule in heart failure. Conversely, reduction in constitutive regulation by PKA has been proposed to underlie the downregulation of atrial I CaL in heart failure. The hypothesis that downregulation of atrial I CaL in heart failure involves reduced channel phosphorylation was examined. Anesthetized adult male Wistar rats underwent surgical coronary artery ligation (CAL, N =10) or equivalent sham-operation (Sham, N =12). Left atrial myocytes were isolated ~18 wk postsurgery and whole cell currents recorded (holding potential=-80 mV). I CaL activated by depolarizing pulses to voltages from -40 to +50 mV were normalized to cell capacitance and current density-voltage relations plotted. CAL cell capacitances were ~1.67-fold greater than Sham ( P ≤ 0.0001). Maximal I CaL conductance ( G max ) was downregulated more than 2-fold in CAL vs. Sham myocytes ( P 50% more effectively in CAL than in Sham so that differences in I CaL density were abolished. Differences between CAL and Sham G max were not abolished by calyculin A (100 nmol/l), suggesting that increased protein dephosphorylation did not account for I CaL downregulation. Treatment with either H-89 (10 μmol/l) or AIP (5 μmol/l) had no effect on basal currents in Sham or CAL myocytes, indicating that, in contrast to ventricular myocytes, neither PKA nor CaMKII regulated basal I CaL Expression of the L-type α 1C -subunit, protein phosphatases 1 and 2A, and inhibitor-1 proteins was unchanged. In conclusion, reduction in PKA-dependent regulation did not contribute to downregulation of atrial I CaL in heart failure. NEW & NOTEWORTHY Whole cell recording of L-type Ca 2+ currents in atrial myocytes from rat hearts subjected to coronary artery ligation compared with those from sham-operated controls reveals marked reduction in current density in heart failure without change in channel subunit

  4. Falling film evaporation on a tube bundle with plain and enhanced tubes

    International Nuclear Information System (INIS)

    Habert, M.

    2009-04-01

    The complexities of two-phase flow and evaporation on a tube bundle present important problems in the design of heat exchangers and the understanding of the physical phenomena taking place. The development of structured surfaces to enhance boiling heat transfer and thus reduce the size of evaporators adds another level of complexity to the modeling of such heat exchangers. Horizontal falling film evaporators have the potential to be widely used in large refrigeration systems and heat pumps, in the petrochemical industry and for sea water desalination units, but there is a need to improve the understanding of falling film evaporation mechanisms to provide accurate thermal design methods. The characterization of the effect of enhanced surfaces on the boiling phenomena occurring in falling film evaporators is thus expected to increase and optimize the performance of a tube bundle. In this work, the existing LTCM falling film facility was modified and instrumented to perform falling film evaporation measurements on single tube row and a small tube bundle. Four types of tubes were tested including: a plain tube, an enhanced condensing tube (Gewa-C+LW) and two enhanced boiling tubes (Turbo-EDE2 and Gewa-B4) to extend the existing database. The current investigation includes results for two refrigerants, R134a and R236fa, at a saturation temperature of T sat = 5 °C, liquid film Reynolds numbers ranging from 0 to 3000, at heat fluxes between 20 and 60 kW/m² in pool boiling and falling film configurations. Measurements of the local heat transfer coefficient were obtained and utilized to improve the current prediction methods. Finally, the understanding of the physical phenomena governing the falling film evaporation of liquid refrigerants has been improved. Furthermore, a method for predicting the onset of dry patch formation has been developed and a local heat transfer prediction method for falling film evaporation based on a large experimental database has been proposed

  5. Diamagnetic composite material structure for reducing undesired electromagnetic interference and eddy currents in dielectric wall accelerators and other devices

    Science.gov (United States)

    Caporaso, George J.; Poole, Brian R.; Hawkins, Steven A.

    2015-06-30

    The devices, systems and techniques disclosed here can be used to reduce undesired effects by magnetic field induced eddy currents based on a diamagnetic composite material structure including diamagnetic composite sheets that are separated from one another to provide a high impedance composite material structure. In some implementations, each diamagnetic composite sheet includes patterned conductor layers are separated by a dielectric material and each patterned conductor layer includes voids and conductor areas. The voids in the patterned conductor layers of each diamagnetic composite sheet are arranged to be displaced in position from one patterned conductor layer to an adjacent patterned conductor layer while conductor areas of the patterned conductor layers collectively form a contiguous conductor structure in each diamagnetic composite sheet to prevent penetration by a magnetic field.

  6. Development and Technology Transfer of the Syncro Blue Tube (Gabriel) Magnetically Guided Feeding Tube

    Science.gov (United States)

    2017-06-01

    suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188...the tube to the 110 cm mark. At the 110 cm mark, secure the tube with medical tape and remove the stylet completely allowing enough tube slack ...and it provides slack that allows tube to advance distally by the effect of natural peristalsis on the bolus-sized balloon. Results: Most feeding

  7. Eustachian tube patency

    Science.gov (United States)

    Eustachian tube patency refers to how much the eustachian tube is open. The eustachian tube runs between the middle ear and the throat. It controls the pressure behind the eardrum and middle ear space. This helps keep ...

  8. Feeding tube - infants

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007235.htm Feeding tube - infants To use the sharing features on this page, please enable JavaScript. A feeding tube is a small, soft, plastic tube placed ...

  9. Efforts Aimed To Reduce Attrition in Antimalarial Drug Discovery: A Systematic Evaluation of the Current Antimalarial Targets Portfolio.

    Science.gov (United States)

    Chaparro, María Jesús; Calderón, Félix; Castañeda, Pablo; Fernández-Alvaro, Elena; Gabarró, Raquel; Gamo, Francisco Javier; Gómez-Lorenzo, María G; Martín, Julio; Fernández, Esther

    2018-04-13

    Malaria remains a major global health problem. In 2015 alone, more than 200 million cases of malaria were reported, and more than 400,000 deaths occurred. Since 2010, emerging resistance to current front-line ACTs (artemisinin combination therapies) has been detected in endemic countries. Therefore, there is an urgency for new therapies based on novel modes of action, able to relieve symptoms as fast as the artemisinins and/or block malaria transmission. During the past few years, the antimalarial community has focused their efforts on phenotypic screening as a pragmatic approach to identify new hits. Optimization efforts on several chemical series have been successful, and clinical candidates have been identified. In addition, recent advances in genetics and proteomics have led to the target deconvolution of phenotypic clinical candidates. New mechanisms of action will also be critical to overcome resistance and reduce attrition. Therefore, a complementary strategy focused on identifying well-validated targets to start hit identification programs is essential to reinforce the clinical pipeline. Leveraging published data, we have assessed the status quo of the current antimalarial target portfolio with a focus on the blood stage clinical disease. From an extensive list of reported Plasmodium targets, we have defined triage criteria. These criteria consider genetic, pharmacological, and chemical validation, as well as tractability/doability, and safety implications. These criteria have provided a quantitative score that has led us to prioritize those targets with the highest probability to deliver successful and differentiated new drugs.

  10. Reduced Hyperpolarization-Activated Current Contributes to Enhanced Intrinsic Excitability in Cultured Hippocampal Neurons from PrP(-/-) Mice.

    Science.gov (United States)

    Fan, Jing; Stemkowski, Patrick L; Gandini, Maria A; Black, Stefanie A; Zhang, Zizhen; Souza, Ivana A; Chen, Lina; Zamponi, Gerald W

    2016-01-01

    Genetic ablation of cellular prion protein (PrP(C)) has been linked to increased neuronal excitability and synaptic activity in the hippocampus. We have previously shown that synaptic activity in hippocampi of PrP-null mice is increased due to enhanced N-methyl-D-aspartate receptor (NMDAR) function. Here, we focused on the effect of PRNP gene knock-out (KO) on intrinsic neuronal excitability, and in particular, the underlying ionic mechanism in hippocampal neurons cultured from P0 mouse pups. We found that the absence of PrP(C) profoundly affected the firing properties of cultured hippocampal neurons in the presence of synaptic blockers. The membrane impedance was greater in PrP-null neurons, and this difference was abolished by the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker ZD7288 (100 μM). HCN channel activity appeared to be functionally regulated by PrP(C). The amplitude of voltage sag, a characteristic of activating HCN channel current (I h), was decreased in null mice. Moreover, I h peak current was reduced, along with a hyperpolarizing shift in activation gating and slower kinetics. However, neither HCN1 nor HCN2 formed a biochemical complex with PrP(C). These results suggest that the absence of PrP downregulates the activity of HCN channels through activation of a cell signaling pathway rather than through direct interactions. This in turn contributes to an increase in membrane impedance to potentiate neuronal excitability.

  11. Motivation to Reduce Risk Behaviors While in Prison: Qualitative Analysis of Interviews with Current and Formerly Incarcerated Women.

    Science.gov (United States)

    Abad, Neetu; Carry, Monique; Herbst, Jeffrey H; Fogel, Catherine I

    2013-10-01

    Prison is an environment in which programs can be implemented to change harmful behaviors among high-risk populations. Incarcerated women experience high rates of HIV and other sexually transmitted diseases (STDs), yet little research has examined women's motivation to reduce risky behaviors during incarceration. In-depth individual interviews were conducted with former and current women prisoners in two North Carolina correctional facilities and analyzed to identify barriers and facilitators of behavior change while in prison. Analyses revealed key motivators of behavior change: Viewing prison as a place to recover from past trauma, removing oneself from negative social networks, gaining access to needed mental and physical health services, and engaging in self-care and self-reflection. Barriers to behavior change include fear of recidivism, stigma of being in prison, and return to undesirable social networks post-release. Moreover, women noted that the provision of mental health services, educational enhancement and housing assistance could help them reduce engagement in high-risk behaviors after their incarceration. These findings can be incorporated into HIV/STD risk reduction interventions to facilitate positive behavior change among incarcerated women prisoners. Prison itself is a tremendous education in the need for patience and perseverance. It is above all a test of one's commitment.-Nelson Mandela, 1995.

  12. Tube holding system

    International Nuclear Information System (INIS)

    Cunningham, R.C.

    1978-01-01

    A tube holding rig is described for the lateral support of tubes arranged in tight parcels in a heat exchanger. This tube holding rig includes not less than two tube supporting assemblies, with a space between them, located crosswise with respect to the tubes, each supporting assembly comprising a first set of parallel components in contact with the tubes, whilst a second set of components is also in contact with the tubes. These two sets of parts together define apertures through which the tubes pass [fr

  13. Re-examination of demonstration gas discharge tubes

    International Nuclear Information System (INIS)

    Maharaj, H.P.

    1991-01-01

    Gas discharge tubes in which electrons or ions are accelerated at voltages on the order of kilovolts to produce observable atomic effects are potential x-ray sources. These tubes come in various shapes, sizes and designs, and are still in use in science classrooms despite the decline predicted in the 1970s. Because of current applications, a representative sample consisting of fifteen tubes marketed over a recent 2-year period was reexamined for regulatory compliance, product identification and advertising. The results revealed that: poor quality control and design can affect x-ray emissions; and deficiencies exist in product identification, safe use guidelines and operating instructions. This paper reports that these findings, together with the dose estimates, implications and subjective indicators, strongly suggest a user group of unknown size is at increased risk. A combination of enhanced surveillance and promotion of user awareness strategies is adopted to reduce and possible eliminate the potential health risks

  14. Leakproof Swaged Joints in Thin-Wall Tubing

    Science.gov (United States)

    Stuckenberg, F. H.; Crockett, L. K.; Snyder, W. E.

    1986-01-01

    Tubular inserts reinforce joints, reducing incidence of leaks. In new swaging technique, tubular inserts placed inside ends of both tubes to be joined. Made from thicker-wall tubing with outside diameter that matches inside diameter of thin tubing swaged, inserts support tube ends at joint. They ensure more uniform contact between swage fitting and tubing. New swaging technique developed for Al/Ti/V-alloy hydraulic supply lines.

  15. HV Switch Tube Development Program status report: April 28, 1978

    International Nuclear Information System (INIS)

    Winje, R.A.

    1978-01-01

    The HV Switch Tube Development Program encompassed development contracts to both Eimac (Division of Varian) and RCA. Both companies were required to develop a design for the tube and to build and test two tubes. The development program began in April, 1976. Currently, both companies have built tubes; Eimac has built one and RCA has built two. As initially built, both tubes exhibited unstable operation; however, RCA has implemented design changes which stabilized the tube operation. Eimac has a design modification which they believe will produce stable operation when the change is implemented. Both tubes have been tested to a limited degree and no other abnormal characteristics have been observed

  16. Free compression tube. Applications

    Science.gov (United States)

    Rusu, Ioan

    2012-11-01

    During the flight of vehicles, their propulsion energy must overcome gravity, to ensure the displacement of air masses on vehicle trajectory, to cover both energy losses from the friction between a solid surface and the air and also the kinetic energy of reflected air masses due to the impact with the flying vehicle. The flight optimization by increasing speed and reducing fuel consumption has directed research in the aerodynamics field. The flying vehicles shapes obtained through studies in the wind tunnel provide the optimization of the impact with the air masses and the airflow along the vehicle. By energy balance studies for vehicles in flight, the author Ioan Rusu directed his research in reducing the energy lost at vehicle impact with air masses. In this respect as compared to classical solutions for building flight vehicles aerodynamic surfaces which reduce the impact and friction with air masses, Ioan Rusu has invented a device which he named free compression tube for rockets, registered with the State Office for Inventions and Trademarks of Romania, OSIM, deposit f 2011 0352. Mounted in front of flight vehicles it eliminates significantly the impact and friction of air masses with the vehicle solid. The air masses come into contact with the air inside the free compression tube and the air-solid friction is eliminated and replaced by air to air friction.

  17. Final report on development evaluation of Task Group 3 pressure tubes

    International Nuclear Information System (INIS)

    Fleck, R.G.; Price, E.G.; Cheadle, B.A.

    1983-11-01

    This report describes the production and evaluation of pressure tubes manufactured to the recommendations of Task Group 3 (TG3) of the Creep Engineering Design Plan. The Zr-2.5 wt percent Nb tubes were manufactured by modified production route to change their metallurgical structure and so reduce the in-service elongation rates. Three modified routes were investigated and a total of twenty-eight tubes produced. There were no difficulties in manufacture and the tubes satisfied the quality assurance and design specifications of reactor grade tubes. Metallurgical evaluation showed that the expected changes in microstructure had occurred but not to the extent anticipated. The TG3 tubes were found to have comparable properties to current tubes when tested for: tensile strength (irradiated and unirradiated); hydride cracking; stress to reorient hydrides; hydrogen diffusion; flaw tolerance; corrosion (irradiated and unirradiated); wear; rolled joint characteristics; irradiation creep and growth. Lower in-service elongation rates are expected for tubes produced by two of the modified routes

  18. Development of Zr-2.5Nb pressure tubes for Advanced CANDU Reactor

    International Nuclear Information System (INIS)

    Bickel, G.A.; Griffiths, M.; Douchant, A.; Douglas, S.; Woo, O.T.; Buyers, A.

    2010-01-01

    In an Advanced CANDU Reactor (ACR), pressure tubes of cold-worked Zr-2.5Nb materials will be used in the reactor core to contain the fuel bundles and the light water coolant. They will be subjected to higher temperature, pressure and flux than that in a CANDU reactor. In order to ensure that these tubes will perform acceptably over their 30-year design life in such an environment, a manufacturing process has been developed to produce 6.5 mm thick ACR pressure tubes with optimized chemical composition, improved mechanical properties and in-reactor behaviour. The test and examination results show that, when compared with current in-service pressure tubes, the mechanical properties of ACR pressure tubes are significantly improved. Based on previous experience with CANDU reactor pressure tubes an assessment of the grain structure and texture indicates that the in-reactor creep deformation will be improved also. Analysis of the distribution of texture parameters from a trial batch of 26 tubes shows that the variability is reduced relative to tubes fabricated in the past. This reduction in variability together with a shift to a coarser grain structure will result in a reduction in diametral creep design limits and thus a longer economic life for the fuel channels of the advanced CANDU reactor. (author)

  19. Integrity Analysis of Damaged Steam Generator Tubes

    International Nuclear Information System (INIS)

    Stanic, D.

    1998-01-01

    Variety of degradation mechanisms affecting steam generator tubes makes steam generators as one of the critical components in the nuclear power plants. Depending of their nature, degradation mechanisms cause different types of damages. It requires performance of extensive integrity analysis in order to access various conditions of crack behavior under operating and accidental conditions. Development and application of advanced eddy current techniques for steam generator examination provide good characterization of found damages. Damage characteristics (shape, orientation and dimensions) may be defined and used for further evaluation of damage influence on tube integrity. In comparison with experimental and analytical methods, numerical methods are also efficient tools for integrity assessment. Application of finite element methods provides relatively simple modeling of different type of damages and simulation of various operating conditions. The stress and strain analysis may be performed for elastic and elasto-plastic state with good ability for visual presentation of results. Furthermore, the fracture mechanics parameters may be calculated. Results obtained by numerical analysis supplemented with experimental results are the base for definition of alternative plugging criteria which may significantly reduce the number of plugged tubes. (author)

  20. Bender/Coiler for Tubing

    Science.gov (United States)

    Stoltzfus, J. M.

    1983-01-01

    Easy-to-use tool makes coils of tubing. Tubing to be bend clamped with stop post. Die positioned snugly against tubing. Operator turns handle to slide die along tubing, pushing tubing into spiral groove on mandrel.

  1. A Method for the Automatic Exposure Control in Pediatric Abdominal CT: Application to the Standard Deviation Value and Tube Current Methods by Using Patient's Age and Body Size.

    Science.gov (United States)

    Furuya, Ken; Akiyama, Shinji; Nambu, Atushi; Suzuki, Yutaka; Hasebe, Yuusuke

    2017-01-01

    We aimed to apply the pediatric abdominal CT protocol of Donnelly et al. in the United States to the pediatric abdominal CT-AEC. Examining CT images of 100 children, we found that the sectional area of the hepatic portal region (y) was strongly correlated with the body weight (x) as follows: y=7.14x + 84.39 (correlation coefficient=0.9574). We scanned an elliptical cone phantom that simulates the human body using a pediatric abdominal CT scanning method of Donnelly et al. in, and measured SD values. We further scanned the same phantom under the settings for adult CT-AEC scan and obtained the relationship between the sectional areas (y) and the SD values. Using these results, we obtained the following preset noise factors for CT-AEC at each body weight range: 6.90 at 4.5-8.9 kg, 8.40 at 9.0-17.9 kg, 8.68 at 18.0-26.9 kg, 9.89 at 27.0-35.9 kg, 12.22 at 36.0-45.0 kg, 13.52 at 45.1-70.0 kg, 15.29 at more than 70 kg. From the relation between age, weight and the distance of liver and tuber ischiadicum of 500 children, we obtained the CTDI vol values and DLP values under the scanning protocol of Donnelly et al. Almost all of DRL from these values turned out to be smaller than the DRL data of IAEA and various countries. Thus, by setting the maximum current values of CT-AEC to be the Donnelly et al.'s age-wise current values, and using our weight-wise noise factors, we think we can perform pediatric abdominal CT-AEC scans that are consistent with the same radiation safety and the image quality as those proposed by Donnelly et al.

  2. Motor/Prefrontal Transcranial Direct Current Stimulation (tDCS) Following Lumbar Surgery Reduces Postoperative Analgesia Use.

    Science.gov (United States)

    Glaser, John; Reeves, Scott T; Stoll, William David; Epperson, Thomas I; Hilbert, Megan; Madan, Alok; George, Mark S; Borckardt, Jeffrey J

    2016-05-01

    Randomized, controlled pilot trial. The present study is the first randomized, double-blind, sham-controlled pilot clinical trial of transcranial direct current stimulation (tDCS) for pain and patient-controlled analgesia (PCA) opioid usage among patients receiving spine surgery. Lumbar spinal surgeries are common, and while pain is often a complaint that precedes surgical intervention, the procedures themselves are associated with considerable postoperative pain lasting days to weeks. Adequate postoperative pain control is an important factor in determining recovery and new analgesic strategies are needed that can be used adjunctively to existing strategies potentially to reduce reliance on opioid analgesia. Several novel brain stimulation technologies including tDCS are beginning to demonstrate promise as treatments for a variety of pain conditions. Twenty-seven patients undergoing lumbar spine procedures at Medical University of South Carolina were randomly assigned to receive four 20-minute sessions of real or sham tDCS during their postsurgical hospital stay. Patient-administered hydromorphone usage was tracked along with numeric rating scale pain ratings. The effect of tDCS on the slope of the cumulative PCA curve was significant (P tDCS was associated with a 23% reduction in PCA usage. In the real tDCS group a 31% reduction was observed in pain-at-its-least ratings from admission to discharge (P = 0.027), but no other changes in numeric rating scale pain ratings were significant in either group. The present pilot trial is the first study to demonstrate an opioid sparing effect of tDCS after spine surgical procedures. Although this was a small pilot trial in a heterogeneous sample of spinal surgery patients, a moderate effect-size was observed for tDCS, suggesting that future work in this area is warranted. 2.

  3. Evaluation of Two Passes Cold Pilgering Property for PLUS7TM Guide Thimble and Instrumentation Tubing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Min Young; Park, Ki Bum; Kim, In Kyu; Lee, Young Hee; Kahng, Jong Yeol [KEPCO Nuclear Fuel Co., Daejeon (Korea, Republic of)

    2015-05-15

    The thermo-mechanical property of zirconium alloy tube is well known to be influenced by pilgering pass schedule and its tooling; thus the control of its microstructure and mechanical property in the final tube production stage for nuclear fuel applications is a major concern of tube manufacture. To fabricate final tube, the 3 passes pilgering is applied in general by using TREX(Tube Reduced EXtrusion), 63.5mm outer diameter(OD), in KEPCO NF and most of Zr tube manufacturing companies. They are also taking big efforts to reduce pilgering step for the sake of increasing the efficiency of production in the forming stage of tube. The objective of this study is to develop two passes of pilgering schedule from the conventional three passes of pilgering schedule for manufacturing the Guide Thimble and Instrumentation tube conforming to specification, which are newly developing component for the advanced nuclear fuel assembly in KEPCO NF. CSR, hydride orientation, and structural integrity are well conformed to the desired targets so it is expected that both die and mandrel were newly designed for the PLUS7TM guide thimble and instrumentation tube with higher Q factor for two passes of pilgering at 50LC and 25LC pilger machine, instead of three passes of pilgering, are able to be applicable to this design of fuel component. If developed two passes pilgering is applied to current manufacturing process, it would improve not only productivity but also yield rate by reducing 3 steps(pilgering, heat-treatment, pickiling and cleaning) of manufacturing process. But additional tests(including in-pile test) should be performed in order to evaluate integrity in reactor.

  4. Autologous fibrin sealant reduces the incidence of prolonged air leak and duration of chest tube drainage after lung volume reduction surgery: a prospective randomized blinded study.

    Science.gov (United States)

    Moser, C; Opitz, I; Zhai, W; Rousson, V; Russi, E W; Weder, W; Lardinois, D

    2008-10-01

    Prolonged air leak is reported in up to 50% of patients after lung volume reduction surgery. The effect of an autologous fibrin sealant on the intensity and duration of air leak and on the time to chest drain removal after lung volume reduction surgery was investigated in a randomized prospective clinical trial. Twenty-five patients underwent bilateral thoracoscopic lung volume reduction surgery. In each patient, an autologous fibrin sealant was applied along the staple lines on one side, whereas no additional measure was taken on the other side. Randomization of treatment was performed at the end of the resection on the first side. Air leak was assessed semiquantitatively by use of a severity score (0 = no leak; 4 = continuous severe leak) by two investigators blinded to the treatment. Mean value of the total severity scores for the first 48 hours postoperative was significantly lower in the treated group (4.7 +/- 7.7) than in the control group (16.0 +/- 10.1) (P drainage were also significantly reduced after application of the sealant (4.5% and 2.8 +/- 1.9 days versus 31.8% and 5.9 +/- 2.9 days) (P = .03 and P drainage.

  5. photomultiplier tube

    CERN Multimedia

    A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  6. photomultiplier tube

    CERN Multimedia

    Philips. 150AVP. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  7. Tube-support response to tube-denting evaluation. Volume 1. Final report

    International Nuclear Information System (INIS)

    Anderson, P.L.; Hall, J.F.; Shah, P.K.; Wills, R.L.

    1983-05-01

    The response of the tube supports is one of the important considerations of tube denting in a steam generator. Investigations have indicated that damaged tube supports have the potential to distort and damage tubes. This investigation considers the response to tube denting of the Combustion Engineering type tube supports. Drilled support plates and eggcrate tube supports are tested in a model steam generator in which tube denting is induced. The experimental data is used to verify and refine analytical predictor models developed using finite element techniques. It was found that analytical models underpredicted the deformations of the tube supports and appropriate modifications to enhance the predictive capability are identified. Non-destructive examination methods are evaluated for application to operating steam generators. It was found that the standard eddy current and profilometry techniques are acceptable methods for determining tube deformations, but these techniques are not adequate to assess tube support damage. Radiography is judged to be the best available means of determining the extent and progression of damage in tube supports

  8. A Study on the Profile Change Measurement of Steam Generator Tubes with Tube Expansion Methods

    International Nuclear Information System (INIS)

    Kim, Young Kyu; Song Myung Ho; Choi, Myung Sik

    2011-01-01

    Steam generator tubes for nuclear power plants contain the local shape transitions on their inner or outer surface such as dent, bulge, over-expansion, eccentricity, deflection, and so on by the application of physical force during the tube manufacturing and steam generator assembling and by the sludge (that is, corrosion products) produced during the plant operation. The structural integrity of tubes will be degraded by generating the corrosive crack at that location. The profilometry using the traditional bobbin probes which are currently applied for measuring the profile change of tubes gives us basic information such as axial locations and average magnitudes of deformations. However, the three-dimensional quantitative evaluation on circumferential locations, distributional angle, and size of deformations will have to be conducted to understand the effects of residual stresses increased by local deformations on corrosive cracking of tubes. Steam generator tubes of Korean standard nuclear power plants expanded within their tube-sheets by the explosive expansion method and suffered from corrosive cracks in the early stage of power operation. Thus, local deformations of steam generator tubes at the top of tube-sheet were measured with an advanced rotating probe and a laser profiling system for the two cases where the tubes expanded by the explosive expansion method and hydraulic expansion. Also, the trends of eccentricity, deflection, and over-expansion of tubes were evaluated. The advanced eddy current profilometry was confirmed to provide accurate information of local deformations compared with laser profilometry

  9. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Program Vision and Aging Program African American Program Training and Jobs Fellowships NEI Summer Intern Program Diversity In Vision Research & Ophthalmology (DIVRO) Student Training Programs To search for current job openings visit HHS USAJobs Home >> NEI YouTube Videos >> ...

  10. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... and Aging Program African American Program Training and Jobs Fellowships NEI Summer Intern Program Diversity In Vision ... DIVRO) Student Training Programs To search for current job openings visit HHS USAJobs Home » NEI YouTube Videos » ...

  11. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Program Vision and Aging Program African American Program Training and Jobs Fellowships NEI Summer Intern Program Diversity In Vision Research & Ophthalmology (DIVRO) Student Training Programs To search for current job openings visit HHS USAJobs Home » NEI YouTube Videos » ...

  12. Assessment and management of ageing of major nuclear power plant components important to safety: CANDU pressure tubes

    International Nuclear Information System (INIS)

    1998-08-01

    The report documents the current practices for assessment and management of the ageing of the pressure tubes in CANDU reactors and Indian PHWTRs. Chapter headings are: fuel channel and pressure tube description, design basis for the fuel channel and pressure tube, degradation mechanisms and ageing concerns for pressure tubes, inspection and monitoring methods for pressure tubes,assessment methods and fitness-for-service guidelines for pressure tubes, mitigation methods for pressure tubes, and pressure tube ageing management programme

  13. Slit/Robo1 signaling regulates neural tube development by balancing neuroepithelial cell proliferation and differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guang; Li, Yan; Wang, Xiao-yu [Key Laboratory for Regenerative Medicine of The Ministry of Education, Department of Histology and Embryology, School of Medicine, Jinan University, Guangzhou 510632 (China); Han, Zhe [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Chuai, Manli [College of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH (United Kingdom); Wang, Li-jing [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Ho Lee, Kenneth Ka [Stem Cell and Regeneration Thematic Research Programme, School of Biomedical Sciences, Chinese University of Hong Kong, Shatin (Hong Kong); Geng, Jian-guo, E-mail: jgeng@umich.edu [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI 48109 (United States); Yang, Xuesong, E-mail: yang_xuesong@126.com [Key Laboratory for Regenerative Medicine of The Ministry of Education, Department of Histology and Embryology, School of Medicine, Jinan University, Guangzhou 510632 (China)

    2013-05-01

    Formation of the neural tube is the morphological hallmark for development of the embryonic central nervous system (CNS). Therefore, neural tube development is a crucial step in the neurulation process. Slit/Robo signaling was initially identified as a chemo-repellent that regulated axon growth cone elongation, but its role in controlling neural tube development is currently unknown. To address this issue, we investigated Slit/Robo1 signaling in the development of chick neCollege of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH, UKural tube and transgenic mice over-expressing Slit2. We disrupted Slit/Robo1 signaling by injecting R5 monoclonal antibodies into HH10 neural tubes to block the Robo1 receptor. This inhibited the normal development of the ventral body curvature and caused the spinal cord to curl up into a S-shape. Next, Slit/Robo1 signaling on one half-side of the chick embryo neural tube was disturbed by electroporation in ovo. We found that the morphology of the neural tube was dramatically abnormal after we interfered with Slit/Robo1 signaling. Furthermore, we established that silencing Robo1 inhibited cell proliferation while over-expressing Robo1 enhanced cell proliferation. We also investigated the effects of altering Slit/Robo1 expression on Sonic Hedgehog (Shh) and Pax7 expression in the developing neural tube. We demonstrated that over-expressing Robo1 down-regulated Shh expression in the ventral neural tube and resulted in the production of fewer HNK-1{sup +} migrating neural crest cells (NCCs). In addition, Robo1 over-expression enhanced Pax7 expression in the dorsal neural tube and increased the number of Slug{sup +} pre-migratory NCCs. Conversely, silencing Robo1 expression resulted in an enhanced Shh expression and more HNK-1{sup +} migrating NCCs but reduced Pax7 expression and fewer Slug{sup +} pre-migratory NCCs were observed. In conclusion, we propose that Slit/Robo1 signaling is involved in regulating neural tube

  14. Framatome recent developments and application on site in NDE of steam generator tubes

    International Nuclear Information System (INIS)

    Bieth, M.

    1986-01-01

    The increasing needs concerning the follow up and expertise of PWR steam generator (SG) tubing have led Framatome to develop a quick on-site intervention mobile unit, which could implement any current technique and equipment. Besides, Framatome has developed several non destructrive examination methods to solve the specific problems encountered in service on the SG tubes: profilometry of the SG tubes by eddy current. Inside and above the tube sheet, eddy current inspection of tube sleeving by ultrasonic testing and eddy current

  15. Dynamics of explosively imploded pressurized tubes

    Science.gov (United States)

    Szirti, Daniel; Loiseau, Jason; Higgins, Andrew; Tanguay, Vincent

    2011-04-01

    The detonation of an explosive layer surrounding a pressurized thin-walled tube causes the formation of a virtual piston that drives a precursor shock wave ahead of the detonation, generating very high temperatures and pressures in the gas contained within the tube. Such a device can be used as the driver for a high energy density shock tube or hypervelocity gas gun. The dynamics of the precursor shock wave were investigated for different tube sizes and initial fill pressures. Shock velocity and standoff distance were found to decrease with increasing fill pressure, mainly due to radial expansion of the tube. Adding a tamper can reduce this effect, but may increase jetting. A simple analytical model based on acoustic wave interactions was developed to calculate pump tube expansion and the resulting effect on the shock velocity and standoff distance. Results from this model agree quite well with experimental data.

  16. Fuel assembly and fuel cladding tube

    International Nuclear Information System (INIS)

    Tsutsumi, Shinro; Ito, Ken-ichi; Inagaki, Masatoshi; Nakajima, Junjiro.

    1996-01-01

    A fuel cladding tube is a zirconium liner tube formed by lining a pure zirconium layer on the inner side of a zirconium alloy tube. The fuel cladding tube is formed by extrusion molding of a composite billet formed by inserting a pure zirconium billet into a zirconium alloy billet. Accordingly, the pure zirconium layer and the zirconium alloy tube are strongly joined by metal bond. The fuel cladding tube has an external oxide film on the outer surface of the zirconium alloy tube and an internal oxide film on the inner side of the pure zirconium layer. The external oxide film has a thickness preferably of about 1μm. The internal oxide film has a thickness of not more than 10μm, preferably, from 1 to 5μm. With such a constitution, flaws to be formed on both inner and outer surfaces of the cladding tube upon assembling a fuel assembly can be reduced thereby enabling to reduce the amount of hydrogen absorbed to the cladding tube. (I.N.)

  17. Opposed slant tube diabatic sorber

    Science.gov (United States)

    Erickson, Donald C.

    2004-01-20

    A sorber comprised of at least three concentric coils of tubing contained in a shell with a flow path for liquid sorbent in one direction, a flow path for heat transfer fluid which is in counter-current heat exchange relationship with sorbent flow, a sorbate vapor port in communication with at least one of sorbent inlet or exit ports, wherein each coil is coiled in opposite direction to those coils adjoining it, whereby the opposed slant tube configuration is achieved, with structure for flow modification in the core space inside the innermost coil.

  18. Externally finned circular tube immerse in a phase-change material

    International Nuclear Information System (INIS)

    Alves, C.L.F.; Ismail, K.A.R.

    1985-01-01

    In an attempt to increase the heat transfer rate and reduce the convective currents during the freezing of phase change materials (PCM) in storage tanks, externally finned circular tubes are studied experimentally. The parameters analysed in this work include number of fins, fin length, initial degree of superheat and freezing time

  19. A transformerless single-phase symmetrical Z-source HERIC inverter with reduced leakage currents for PV systems

    DEFF Research Database (Denmark)

    Li, Kerui; Shen, Yanfeng; Yang, Yongheng

    2018-01-01

    and thus low leakage currents in PV applications. The symmetric Z-source HERIC inverter requires two extra active switches. Nevertheless, the operation frequency of the two switches is the line frequency, leading to negligible losses. More importantly, the performance in terms of low leakage currents...... and harmonics is improved. Experimental tests are performed to validate the analysis and performance of the proposed system....

  20. Current-horn suppression for reduced coherent-synchrotron-radiation-induced emittance growth in strong bunch compression

    Directory of Open Access Journals (Sweden)

    T. K. Charles

    2017-03-01

    Full Text Available Control of coherent synchrotron radiation (CSR-induced emittance growth is essential in linear accelerators designed to deliver very high brightness electron beams. Extreme current values at the head and tail of the electron bunch, resulting from strong bunch compression, are responsible for large CSR production leading to significant transverse projected emittance growth. The Linac Coherent Light Source (LCLS truncates the head and tail current spikes which greatly improves free electron laser (FEL performance. Here we consider the underlying dynamics that lead to formation of current spikes (also referred to as current horns, which has been identified as caustics forming in electron trajectories. We present a method to analytically determine conditions required to avoid the caustic formation and therefore prevent the current spikes from forming. These required conditions can be easily met, without increasing the transverse slice emittance, through inclusion of an octupole magnet in the middle of a bunch compressor.

  1. Photomultiplier tubes for Low Level Cerenkov Detectors

    International Nuclear Information System (INIS)

    Strindehag, O.

    1965-03-01

    Tube backgrounds of several 2-inch photomultiplier types having S11, 'S' , S13 and S20 cathodes are compared by measuring signal and background pulse height distributions at pulse heights corresponding to a few photo-electrons. The reference signal is generated by means of a β-source and a plexiglass radiator. It is found that comparatively good results are obtained with selected tubes of the EMI types 6097B and 9514B having equivalent dark current dc values down to 10 -12 input lumens. Special interest is devoted to the correlation between the measured tube backgrounds and the dark current dc values of the tubes, as a good correlation between these parameters simplifies the selection of photomultiplier tubes. The equivalent dark currents of the tested tubes extend over the range 10 -12 to 10 -9 input lumens. Although the investigation deals with photomultiplier tubes intended for use in low level Cerenkov detectors it is believed that the results could be valuable in other fields where photomultiplier tubes are utilized for the detection of weak light pulses

  2. Photomultiplier tubes for Low Level Cerenkov Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Strindehag, O

    1965-03-15

    Tube backgrounds of several 2-inch photomultiplier types having S11, 'S' , S13 and S20 cathodes are compared by measuring signal and background pulse height distributions at pulse heights corresponding to a few photo-electrons. The reference signal is generated by means of a {beta}-source and a plexiglass radiator. It is found that comparatively good results are obtained with selected tubes of the EMI types 6097B and 9514B having equivalent dark current dc values down to 10{sup -12} input lumens. Special interest is devoted to the correlation between the measured tube backgrounds and the dark current dc values of the tubes, as a good correlation between these parameters simplifies the selection of photomultiplier tubes. The equivalent dark currents of the tested tubes extend over the range 10{sup -12} to 10{sup -9} input lumens. Although the investigation deals with photomultiplier tubes intended for use in low level Cerenkov detectors it is believed that the results could be valuable in other fields where photomultiplier tubes are utilized for the detection of weak light pulses.

  3. Development of a light weighted mobile robot for SG tube inspection in NPP

    International Nuclear Information System (INIS)

    Seo, Yong Chil; Jeong, Kyung Min; Shin, Hochul; Gweng, Jung Ju; Lee, Sung Uk; Jeong, Seung Ho; Choi, Young Soo; Kim, Seung Ho; Shin, Chun Sup; Park, Ki Tae

    2012-01-01

    Steam generators (SG) are among the most critical components of pressurized water Nuclear Power Plants (NPP). SG tubes must provide a reliable pressure boundary between the primary and secondary cooling water, because any leakage from tube defects could result in the release of radioactivity to the environment. Thus degradations of steam generators tubes should be monitored and inspected periodically under nuclear regulation. In service inspections of SG tubes are carried out using eddy current test (ECT) and the defected tubes are usually plugged. Because the radioactivity in the internal SG chambers limits free access of human workers, remote manipulators are required. In South Korea, Manipulators such as the Zet ec SM series and the Westinghouse ROSA series have bee used. Such manipulators are rigidly mounted to man ways or tube sheets of SG. Confusions of the inspected tubes may occur from deflection of the manipulators. To reduce the deflections of the manipulators for covering the large working areas of tube sheets, sufficient rigidity is required and that leads to an increase of the weight. Such weight increase results in some difficulties for handling and more radiation exposure of human workers. Recently light weighed mobile robots have been introduced by Westinghouse and Zet ec. The robots can move keeping in contact with the tube sheets using devices which are commonly called cam locks. They are easier to handle and provide no confusion for the position of the inspected tubes. But when the clamping forces are loosed accidentally, they can be fall down and light repair works can be performed. This paper provides the design results for a lightweight mobile robot which is being developed in cooperation of our institutes

  4. Development of a light weighted mobile robot for SG tube inspection in NPP

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Yong Chil; Jeong, Kyung Min; Shin, Hochul; Gweng, Jung Ju; Lee, Sung Uk; Jeong, Seung Ho; Choi, Young Soo; Kim, Seung Ho [KAERI, Daejeon (Korea, Republic of); Shin, Chun Sup; Park, Ki Tae [Korea Plant Service and Engineering, Busan (Korea, Republic of)

    2012-10-15

    Steam generators (SG) are among the most critical components of pressurized water Nuclear Power Plants (NPP). SG tubes must provide a reliable pressure boundary between the primary and secondary cooling water, because any leakage from tube defects could result in the release of radioactivity to the environment. Thus degradations of steam generators tubes should be monitored and inspected periodically under nuclear regulation. In service inspections of SG tubes are carried out using eddy current test (ECT) and the defected tubes are usually plugged. Because the radioactivity in the internal SG chambers limits free access of human workers, remote manipulators are required. In South Korea, Manipulators such as the Zet ec SM series and the Westinghouse ROSA series have bee used. Such manipulators are rigidly mounted to man ways or tube sheets of SG. Confusions of the inspected tubes may occur from deflection of the manipulators. To reduce the deflections of the manipulators for covering the large working areas of tube sheets, sufficient rigidity is required and that leads to an increase of the weight. Such weight increase results in some difficulties for handling and more radiation exposure of human workers. Recently light weighed mobile robots have been introduced by Westinghouse and Zet ec. The robots can move keeping in contact with the tube sheets using devices which are commonly called cam locks. They are easier to handle and provide no confusion for the position of the inspected tubes. But when the clamping forces are loosed accidentally, they can be fall down and light repair works can be performed. This paper provides the design results for a lightweight mobile robot which is being developed in cooperation of our institutes.

  5. Research and simulation of intense pulsed beam transfer in electrostatic accelerate tube

    International Nuclear Information System (INIS)

    Li Chaolong; Shi Haiquan; Lu Jianqin

    2012-01-01

    To study intense pulsed beam transfer in electrostatic accelerate tube, the matrix method was applied to analyze the transport matrixes in electrostatic accelerate tube of non-intense pulsed beam and intense pulsed beam, and a computer code was written for the intense pulsed beam transporting in electrostatic accelerate tube. Optimization techniques were used to attain the given optical conditions and iteration procedures were adopted to compute intense pulsed beam for obtaining self-consistent solutions in this computer code. The calculations were carried out by using ACCT, TRACE-3D and TRANSPORT for different beam currents, respectively. The simulation results show that improvement of the accelerating voltage ratio can enhance focusing power of electrostatic accelerate tube, reduce beam loss and increase the transferring efficiency. (authors)

  6. Tubing and cable cutting tool

    Science.gov (United States)

    Mcsmith, D. D.; Richardson, J. I. (Inventor)

    1984-01-01

    A hand held hydraulic cutting tool was developed which is particularly useful in deactivating ejection seats in military aircraft rescue operations. The tool consists primarily of a hydraulic system composed of a fluid reservoir, a pumping piston, and an actuator piston. Mechanical cutting jaws are attached to the actuator piston rod. The hydraulic system is controlled by a pump handle. As the pump handle is operated the actuator piston rod is forced outward and thus the cutting jaws are forced together. The frame of the device is a flexible metal tubing which permits easy positioning of the tool cutting jaws in remote and normally inaccessible locations. Bifurcated cutting edges ensure removal of a section of the tubing or cable to thereby reduce the possibility of accidental reactivation of the tubing or cable being severed.

  7. X-ray tubes

    International Nuclear Information System (INIS)

    Young, R.W.

    1979-01-01

    A form of x-ray tube is described which provides satisfactory focussing of the electron beam when the beam extends for several feet from gun to target. Such a tube can be used for computerised tomographic scanning. (UK)

  8. Pressure tube type reactors

    International Nuclear Information System (INIS)

    Komada, Masaoki.

    1981-01-01

    Purpose: To increase the safety of pressure tube type reactors by providing an additional ECCS system to an ordinary ECCS system and injecting heavy water in the reactor core tank into pressure tubes upon fractures of the tubes. Constitution: Upon fractures of pressure tubes, reduction of the pressure in the fractured tubes to the atmospheric pressure in confirmed and the electromagnetic valve is operated to completely isolate the pressure tubes from the fractured portion. Then, the heavy water in the reactor core tank flows into and spontaneously recycles through the pressure tubes to cool the fuels in the tube to prevent their meltdown. By additionally providing the separate ECCS system to the ordinary ECCS system, fuels can be cooled upon loss of coolant accidents to improve the safety of the reactors. (Moriyama, K.)

  9. Gastrostomy feeding tube - bolus

    Science.gov (United States)

    Feeding - gastrostomy tube - bolus; G-tube - bolus; Gastrostomy button - bolus; Bard Button - bolus; MIC-KEY - bolus ... KEY, 3 to 8 weeks after surgery. These feedings will help your child grow strong and healthy. ...

  10. Feeding tube insertion - gastrostomy

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002937.htm Feeding tube insertion - gastrostomy To use the sharing features on this page, please enable JavaScript. A gastrostomy feeding tube insertion is the placement of a feeding ...

  11. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  12. A Method to Establishing Tube Plugging Criterion for Heat Exchangers with Straight Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungnam [KHNP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    The difference of thermal expansion coefficients between the shell and tube materials causes the stress in axial direction of tube. Because of the axial stress due to thermal load, the straight tubes are used for heat exchangers operated in low temperature such as CCW (Component Cooling Water) heat exchangers and condensers. It is inevitable for the materials of the components to be degraded as the power plants become older. The degradation accompanies increasing maintenance cost as well as creating safety issues. The materials and wall thickness of heat exchanger tubes in nuclear power plants are selected to withstand system temperature, pressure, and corrosion. There are many codes and standards to be referred for calculating the minimum thickness of the heat exchanger tube in the designing stage. However, the codes and standards related to show the tube plugging criteria may not exist currently. In this paper, a method to establish the tube plugging criteria of BOP heat exchangers, which is based on the USNRC Regulatory Guide 1.121, is introduced and the tube plugging criteria for the TPCCW heat exchanger of Yonggwang NPP No. 1 and 2. A method to establish the tube plugging criteria of heat exchangers with straight tubes are introduced based on the USNRC Regulatory Guide 1.121. As an example, the tube plugging criterion for the CCW heat exchanger of a nuclear power plant is provided.

  13. Apparatus for securing structural tubes in nuclear reactor fuel assemblies

    International Nuclear Information System (INIS)

    Kerry, J.S.

    1987-01-01

    This patent describes a nuclear reactor fuel assembly having a structural tube with a predetermined inside diameter, a generally cylindrical insert of an axial length substantially smaller than the axial length of the structural tube and having a generally cylindrical passageway of a predetermined diameter smaller than the predetermined inside diameter for providing an effectively reduced inside diameter for the structural tube. The insert comprises: means, having an outside diameter approximately equal to the predetermined inside diameter, for coaxially centering the insert within the structural tube; forming lobes, operable when expanded to locally deform against the structural tube thereby locking the insert within the structural tube

  14. A comparison of tape-tying versus a tube-holding device for securing endotracheal tubes in adults.

    Science.gov (United States)

    Murdoch, E; Holdgate, A

    2007-10-01

    During the transfer of intubated patients, endotracheal tube security is paramount. This study aims to compare two methods of securing an endotracheal tube in adults: tying with a cloth tape versus the Thomas Endotracheal Tube Holder (Laerdal). A manikin-based study was performed using paramedics and critical care doctors (consultants and senior trainees) as participants. Each participant was asked to secure an endotracheal tube that had been placed within the trachea of a manikin a total of six times, the first three times using tied cloth tape and the last three times using a Thomas Endotracheal Tube Holder. Following each 'fixation' and after the participant had left the room, the security of the tube was tested by applying a fixed force laterally and to the right by dropping a 1.25 kg weight a distance of 50 cm. The amount of movement of the tube with respect to the teeth was measured and recorded in millimetres. Two-hundred-and-seventy tube fixations (135 tied vs. 135 tube holder) were performed by 45 participants. The degree of tube movement was significantly higher when the tube was secured with a tie compared with when the tube holder was used (median movement 22 mm vs. 4 mm, P tube holder device minimised tube movement in a manikin model when compared with conventional tape tying. The use of this device when transporting intubated patients may reduce the risk of tube displacement though further clinical studies are warranted.

  15. Feedwater heater tube-to-tubesheet connections

    International Nuclear Information System (INIS)

    Yokell, S.

    1993-01-01

    This paper discusses some practical aspects of expanded, welded, and welded-and-expanded feedwater heater tube-to-tubesheet joints. It outlines elastic-plastic tube expanding theory. It examines uniform-pressure-expanded tube joint strength and correlating roller-expanded joint strength with wall reduction and rolling torque. For materials subject to stress-corrosion cracking (SCC), it recommends heat treating tube ends before expanding. For materials subject to fatigue and tube-end cracking, it advocates two-stage expanding: (1) expanding enough to create firm tube-hole contact over the full tubesheet thickness; and (2) re-expanding at full pressure or torque. The paper emphasizes the desirability of segregating heats of tubing, mapping the tube-heat locations and making the heat map a permanent part of the heater maintenance file. It recommends when to provide TEMA/HEI Power Plant Standard annular grooves for roller-expanding and provides an equation for determining optimum groove width for uniform-pressure expanding. The paper also reviews welding requirements for welds of tubes to tubesheets. The review covers front-face welding before and after expanding and the reasons for welding first. It outlines current thinking about definitions of strength- and seal-welds of front-face welded joint in terms of their functions and load-carrying abilities. It presents a proposal for determining the required size of strength welds for use in Section VIII of the ASME Boiler and Pressure Vessel Code (the Code). It shows why welded-and-expanded feedwater heater tube-to-tubesheet joints should be full-strength and full-depth expanded. It makes recommendations for pressure- and leak-testing. This work also proposes the industry consider butt welding the tubes to the steam-side face of the tubesheet as a regular method of tube joining. The results of a survey of manufacturers practices are appended. 30 refs., 14 figs

  16. 21 CFR 868.5800 - Tracheostomy tube and tube cuff.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tracheostomy tube and tube cuff. 868.5800 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5800 Tracheostomy tube and tube cuff. (a) Identification. A tracheostomy tube and tube cuff is a device intended to be placed into a...

  17. Contrastive Analysis and Research on Negative Pressure Beam Tube System and Positive Pressure Beam Tube System for Mine Use

    Science.gov (United States)

    Wang, Xinyi; Shen, Jialong; Liu, Xinbo

    2018-01-01

    Against the technical defects of universally applicable beam tube monitoring system at present, such as air suction in the beam tube, line clogging, long sampling time, etc., the paper analyzes the current situation of the spontaneous combustion fire disaster forecast of mine in our country and these defects one by one. On this basis, the paper proposes a research thought that improving the positive pressure beam tube so as to substitute the negative pressure beam tube. Then, the paper introduces the beam tube monitoring system based on positive pressure technology through theoretical analysis and experiment. In the comparison with negative pressure beam tube, the paper concludes the advantage of the new system and draws the conclusion that the positive pressure beam tube is superior to the negative pressure beam tube system both in test result and test time. At last, the paper proposes prospect of the beam tube monitoring system based on positive pressure technology.

  18. Heat exchanger tube tool

    International Nuclear Information System (INIS)

    Gugel, G.

    1976-01-01

    Certain types of heat-exchangers have tubes opening through a tube sheet to a manifold having an access opening offset from alignment with the tube ends. A tool for inserting a device, such as for inspection or repair, is provided for use in such instances. The tool is formed by a flexible guide tube insertable through the access opening and having an inner end provided with a connector for connection with the opening of the tube in which the device is to be inserted, and an outer end which remains outside of the chamber, the guide tube having adequate length for this arrangement. A flexible transport hose for internally transporting the device slides inside of the guide tube. This hose is long enough to slide through the guide tube, into the heat-exchanger tube, and through the latter to the extent required for the use of the device. The guide tube must be bent to reach the end of the heat-exchanger tube and the latter may be constructed with a bend, the hose carrying anit-friction elements at interspaced locations along its length to make it possible for the hose to negotiate such bends while sliding to the location where the use of the device is required

  19. Applications of the MapReduce programming framework to clinical big data analysis: current landscape and future trends.

    Science.gov (United States)

    Mohammed, Emad A; Far, Behrouz H; Naugler, Christopher

    2014-01-01

    The emergence of massive datasets in a clinical setting presents both challenges and opportunities in data storage and analysis. This so called "big data" challenges traditional analytic tools and will increasingly require novel solutions adapted from other fields. Advances in information and communication technology present the most viable solutions to big data analysis in terms of efficiency and scalability. It is vital those big data solutions are multithreaded and that data access approaches be precisely tailored to large volumes of semi-structured/unstructured data. THE MAPREDUCE PROGRAMMING FRAMEWORK USES TWO TASKS COMMON IN FUNCTIONAL PROGRAMMING: Map and Reduce. MapReduce is a new parallel processing framework and Hadoop is its open-source implementation on a single computing node or on clusters. Compared with existing parallel processing paradigms (e.g. grid computing and graphical processing unit (GPU)), MapReduce and Hadoop have two advantages: 1) fault-tolerant storage resulting in reliable data processing by replicating the computing tasks, and cloning the data chunks on different computing nodes across the computing cluster; 2) high-throughput data processing via a batch processing framework and the Hadoop distributed file system (HDFS). Data are stored in the HDFS and made available to the slave nodes for computation. In this paper, we review the existing applications of the MapReduce programming framework and its implementation platform Hadoop in clinical big data and related medical health informatics fields. The usage of MapReduce and Hadoop on a distributed system represents a significant advance in clinical big data processing and utilization, and opens up new opportunities in the emerging era of big data analytics. The objective of this paper is to summarize the state-of-the-art efforts in clinical big data analytics and highlight what might be needed to enhance the outcomes of clinical big data analytics tools. This paper is concluded by

  20. Intercostal drainage tube or intracardiac drainage tube?

    Directory of Open Access Journals (Sweden)

    N Anitha

    2016-01-01

    Full Text Available Although insertion of chest drain tubes is a common medical practice, there are risks associated with this procedure, especially when inexperienced physicians perform it. Wrong insertion of the tube has been known to cause morbidity and occasional mortality. We report a case where the left ventricle was accidentally punctured leading to near-exsanguination. This report is to highlight the need for experienced physicians to supervise the procedure and train the younger physician in the safe performance of the procedure.

  1. Intercostal drainage tube or intracardiac drainage tube?

    Science.gov (United States)

    Anitha, N; Kamath, S Ganesh; Khymdeit, Edison; Prabhu, Manjunath

    2016-01-01

    Although insertion of chest drain tubes is a common medical practice, there are risks associated with this procedure, especially when inexperienced physicians perform it. Wrong insertion of the tube has been known to cause morbidity and occasional mortality. We report a case where the left ventricle was accidentally punctured leading to near-exsanguination. This report is to highlight the need for experienced physicians to supervise the procedure and train the younger physician in the safe performance of the procedure.

  2. Extending service life of steam generators by sleeving tubes

    International Nuclear Information System (INIS)

    Gutzwiller, J.E.

    1982-01-01

    Steam generator tubes that are failing due to IGA in the tubesheet crevice can be kept in service by using the basic sealable sleeve design developed by BandW. Variations of the present sleeve design could significantly reduce the number of tubes that must be plugged each year. Sleeving had the potential of keeping 28 percent more tubes in service during 1979. Lowering the overall rate at which tubes are removed from service by plugging will reduce the probability of having to derate the plant or replace the steam generator. Considering tomorrow's replacement power costs, sleeving to keep tubes in service is a practical and sound investment

  3. Inverter-Current-Feedback Resonance-Suppression Method for LCL-Type DG System to Reduce Resonance-Frequency Offset and Grid-Inductance Effect

    DEFF Research Database (Denmark)

    Zhou, Leming; Zhou, Xiaoping; Chen, Yandong

    2018-01-01

    For the LCL-type grid-connected distributed generation system, the grid-current-feedback active damping (GCFAD) methods have a conflict between the resonance-suppression ability and harmonic-currents amplification. For this, an inverter-current-feedback reso-nance-suppression (ICFRS) method without...... additional sensors is proposed to reduce resonance-frequency offset and grid-inductance effect due to its unattenuated damping characteristic under high-frequency bandwidth. By analyzing two types of equivalent impedance models of ICFRS and GCFAD with a high-pass filter (HPF), GCFAD can suppress...

  4. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... YouTube Videos » NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration ... Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia Embedded video for NEI YouTube Videos: ...

  5. Internal ultrasonic testing of steam generator tubes

    International Nuclear Information System (INIS)

    Furlan, J.; Soleille, G.; Chalaye, H.

    1983-01-01

    The ''in situ'' inspection of steam generator tubes uses generally Foucault currents before starting and along its life. This inspection aims at searching cracks and corrosion defects. The Foucault current method is quite badly adapted to ''closed crack'' detection, for it doesn't introduce neither resistivity or magnetic permeability variation, or lack of matter. More, it is sensible to the magnetic properties of the tube itself and to its environment (tubular or support plates). It is why, this first systematic inspection has to be completed by an ultrasonic one allowing to bring new elements in the uncertain cases. A device with an internal probe has been developed. It ''lights'' the tube wall with the aid of a transducer of which beam reflects on a mirror. Operating conditions are the same as for Foucault current testing, that is to say the probe moves inside the tube without rotation of the device (bent parts are excluded) [fr

  6. THE TOPOLOGY OF CANONICAL FLUX TUBES IN FLARED JET GEOMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Lavine, Eric Sander; You, Setthivoine, E-mail: Slavine2@uw.edu, E-mail: syou@aa.washington.edu [University of Washington, 4000 15th Street, NE Aeronautics and Astronautics 211 Guggenheim Hall, Box 352400, Seattle, WA 98195 (United States)

    2017-01-20

    Magnetized plasma jets are generally modeled as magnetic flux tubes filled with flowing plasma governed by magnetohydrodynamics (MHD). We outline here a more fundamental approach based on flux tubes of canonical vorticity, where canonical vorticity is defined as the circulation of the species’ canonical momentum. This approach extends the concept of magnetic flux tube evolution to include the effects of finite particle momentum and enables visualization of the topology of plasma jets in regimes beyond MHD. A flared, current-carrying magnetic flux tube in an ion-electron plasma with finite ion momentum is thus equivalent to either a pair of electron and ion flow flux tubes, a pair of electron and ion canonical momentum flux tubes, or a pair of electron and ion canonical vorticity flux tubes. We examine the morphology of all these flux tubes for increasing electrical currents, different radial current profiles, different electron Mach numbers, and a fixed, flared, axisymmetric magnetic geometry. Calculations of gauge-invariant relative canonical helicities track the evolution of magnetic, cross, and kinetic helicities in the system, and show that ion flow fields can unwind to compensate for an increasing magnetic twist. The results demonstrate that including a species’ finite momentum can result in a very long collimated canonical vorticity flux tube even if the magnetic flux tube is flared. With finite momentum, particle density gradients must be normal to canonical vorticities, not to magnetic fields, so observations of collimated astrophysical jets could be images of canonical vorticity flux tubes instead of magnetic flux tubes.

  7. Studies on defect detectability in banded stainless steel tubes

    International Nuclear Information System (INIS)

    Shyamsunder, M.T.; Rao, B.P.C.; Babu Rao, C.; Jayakumar, T.; Kalyanasundaram, P.; Baldev Raj

    1996-01-01

    During inspection of one batch of stainless steel cladding tubes, a few of the tubes gave rise to continuous large amplitude indications throughout the length of the tube. It was observed that the presence of any defects in such tubes would be impossible to detect, due to the poor signal-to-noise ratio. Detailed investigations regarding the surface profile of the tubes were carried out using a novel technique called the projected interferometry method revealed periodic diametral variations and the same were further confirmed by cross sectional profiling. The feasibility of detecting defects in such banded tubes, using eddy current testing were carried out on tubes with artificial defects. This paper discusses the use of three different eddy current methods and their relative performances for inspection. The specific advantages of the phased array eddy current testing method in unambiguous defect detection in situations similar to the one encountered during the present investigations are also discussed. (author)

  8. Modulation method for a multiple drive system based on a two-stage direct power conversion topology with reduced input current ripple

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2005-01-01

    operation. This is a cost effective topology compared to a standard matrix converter because the multiple three-phase loads share the cost of the controlled rectification stage. A new method to reduce the high frequency ripple from the input current is also proposed based on interleaving the switching...

  9. Fuel bundle to pressure tube fretting in Bruce and Darlington

    Energy Technology Data Exchange (ETDEWEB)

    Norsworthy, A G; Ditschun, A [Atomic Energy of Canada Ltd., Mississauga, ON (Canada)

    1996-12-31

    As the fuel channel elongates due to creep, the fuel string moves relative to the inlet until the fuel pads at the inboard end eventually separate from the spacer sleeve, and the fuel resides on the burnish mark of the pressure tube. The bundle is then supported in a fashion which contributes to increased levels of vibration. Those pads which (due to geometric variation) have contact loads with the pressure tube within a certain range, vibrate, and cause significant fretting on the burnish mark, and further along at the midplane of the bundle. Inspection of the pressure tubes in Bruce A, Bruce B, and Darlington has revealed fret damage up to 0.55 mm at the burnish mark and slightly lower than this at the inlet bundle midplane. To date, all fret marks have been dealt with successfully without the need for tube replacement, but a program of work has been initiated to understand the mechanism and reduce the fretting. Such understanding is necessary to guide future design changes to the fuel bundle, to guide future inspection programs, to guide maintenance programs, and for longer term strategic planning. This paper discusses how the understanding of fretting has evolved and outlines a current hypothesis for the mechanism of fretting. The role of bundle geometry, excitation forces, and reactor conditions are reviewed, along with options under consideration to mitigate damage. (author). 4 refs., 2 tabs., 13 figs.

  10. Fuel bundle to pressure tube fretting in Bruce and Darlington

    International Nuclear Information System (INIS)

    Norsworthy, A.G.; Ditschun, A.

    1995-01-01

    As the fuel channel elongates due to creep, the fuel string moves relative to the inlet until the fuel pads at the inboard end eventually separate from the spacer sleeve, and the fuel resides on the burnish mark of the pressure tube. The bundle is then supported in a fashion which contributes to increased levels of vibration. Those pads which (due to geometric variation) have contact loads with the pressure tube within a certain range, vibrate, and cause significant fretting on the burnish mark, and further along at the midplane of the bundle. Inspection of the pressure tubes in Bruce A, Bruce B, and Darlington has revealed fret damage up to 0.55 mm at the burnish mark and slightly lower than this at the inlet bundle midplane. To date, all fret marks have been dealt with successfully without the need for tube replacement, but a program of work has been initiated to understand the mechanism and reduce the fretting. Such understanding is necessary to guide future design changes to the fuel bundle, to guide future inspection programs, to guide maintenance programs, and for longer term strategic planning. This paper discusses how the understanding of fretting has evolved and outlines a current hypothesis for the mechanism of fretting. The role of bundle geometry, excitation forces, and reactor conditions are reviewed, along with options under consideration to mitigate damage. (author). 4 refs., 2 tabs., 13 figs

  11. Note on current position regarding the development by the UKAEA of Reduced Enrichment fuels for Research and Test Reactors

    International Nuclear Information System (INIS)

    Hickey, B.

    1983-01-01

    The United Kingdom Atomic Energy Authority have an MTR fuel fabrication plant located at Dounreay on the north coast of Scotland. The prime function of the plant is to manufacture fuel elements for the UKAEA's own DIDO and PLUTO heavy water reactors located at their research establishment at Harwell. The plant, which has a capacity of about 1000 fuel elements per annum, also manufactures fuel elements, on a commercial basis, for university reactors in the United Kingdom and for a number of customers in overseas countries. The UKAEA have been manufacturing MTR fuel elements of a wide range of designs for over twenty-five years. Following the initiative of the US Government's RERTR programme, the UKAEA have embarked on a modest programme of MTR fuel manufacturing development., irradiation and post-irradiation examination to establish the techniques required to manufacture fuel elements containing uranium of a significantly lower enrichment than that in the fuel elements they currently manufacture. In the first instance this work is being directed towards the production of fuel elements containing uranium of 45% enrichment. After an initial analysis it was recognised that although a satisfactory 45% enriched version of certain of the designs of fuel elements currently manufactured could probably be produced using established U/Al alloy technology, it would be necessary to utilise powder technology for other elements in order to achieve the higher uranium density required. Studies of published information and consideration of the technology and facilities already available at Dounreay prompted the decision to concentrate on the development Of U 3 O 8 /Al cermet type fuel elements of similar geometry to those currently manufactured. Some of the fuel element designs currently manufactured by the UKAEA are listed: Concentric (Extruded) 74% enriched; Concentric Plates 80% enriched with densities 0.60 and 0.53 g U/ cm 3 ; Flat Plate (Swaged) 80% enriched and Flat Plate

  12. Pediatric cuffed endotracheal tubes

    Directory of Open Access Journals (Sweden)

    Neerja Bhardwaj

    2013-01-01

    Full Text Available Endotracheal intubation in children is usually performed utilizing uncuffed endotracheal tubes for conduct of anesthesia as well as for prolonged ventilation in critical care units. However, uncuffed tubes may require multiple changes to avoid excessive air leak, with subsequent environmental pollution making the technique uneconomical. In addition, monitoring of ventilatory parameters, exhaled volumes, and end-expiratory gases may be unreliable. All these problems can be avoided by use of cuffed endotracheal tubes. Besides, cuffed endotracheal tubes may be of advantage in special situations like laparoscopic surgery and in surgical conditions at risk of aspiration. Magnetic resonance imaging (MRI scans in children have found the narrowest portion of larynx at rima glottides. Cuffed endotracheal tubes, therefore, will form a complete seal with low cuff pressure of <15 cm H 2 O without any increase in airway complications. Till recently, the use of cuffed endotracheal tubes was limited by variations in the tube design marketed by different manufacturers. The introduction of a new cuffed endotracheal tube in the market with improved tracheal sealing characteristics may encourage increased safe use of these tubes in clinical practice. A literature search using search words "cuffed endotracheal tube" and "children" from 1980 to January 2012 in PUBMED was conducted. Based on the search, the advantages and potential benefits of cuffed ETT are reviewed in this article.

  13. Potential role of reduced environmental UV exposure as a driver of the current epidemic of atopic dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob P; Zirwas, Matthew J; Elias, Peter M

    2015-01-01

    The basis for the sudden and dramatic increase in atopic dermatitis (AD) and related atopic diseases in the second half of the 20th century is unclear. The hygiene hypothesis proposes that the transition from rural to urban living leads to reduced childhood exposure to pathogenic microorganisms....... Hence instead of having the normal TH1 bias and immune tolerance because of repeated exposure to pathogens, urban dwellers have TH2 cell immune activity and atopic disease in a more sterile environment. Various other environmental exposures have been implicated in the explosion of AD (and atopic...

  14. Progress in Effect of Nano-modified Coatings and Welding Process Parameters on Wear of Contact Tube for Non-copper Coated Solid Wires

    Directory of Open Access Journals (Sweden)

    LI Zhuo-xin

    2017-12-01

    Full Text Available Environment-friendly non-copper coated solid wire is the main developing trend for gas shielded solid wires, whereas wear of contact tube limits their wide application. The effect of nano-modified coatings and welding process parameters on wear of contact tube for non-copper coated solid wires was reviewed. It was found that the wear of contact tube can be reduced due to the formation of tribo-films on the rubbing surfaces of welding wires against contact tube; it is feasible to decrease contact tube wear when non-copper coated solid wires are coated with nano-modified lubricants, thereby displaying excellent lubricating and thermal or electrical conduction characteristics. The wear of contact tube increases with the increase of welding current. The wear of contact tube is worse in direct-current electrode positive (DCEP than in direct-current electrode negative (DCEN. Arc ablation and electrical erosion are the dominant wear mechanisms of contact tube.

  15. Nursing administration of medication via enteral tubes in adults: a systematic review.

    Science.gov (United States)

    Phillips, Nicole M; Nay, Rhonda

    2007-09-01

    Background  Enteral tubes are frequently inserted as part of medical treatment in a wide range of patient situations. Patients with an enteral tube are cared for by nurses in a variety of settings, including general and specialised acute care areas, aged care facilities and at home. Regardless of the setting, nurses have the primary responsibility for administering medication through enteral tubes. Medication administration via an enteral tube is a reasonably common nursing intervention that entails a number of skills, including preparing the medication, verifying the tube position, flushing the tube and assessing for potential complications. If medications are not given effectively through an enteral tube, harmful consequences may result leading to increased morbidity, for example, tube occlusion, diarrhoea and aspiration pneumonia. There are resultant costs for the health-care system related to possible increased length of stay and increased use of equipment. Presently what is considered to be best practice to give medications through enteral tubes is unknown. Objectives  The objective of this systematic review was to determine the best available evidence on which nursing interventions are effective in minimising the complications associated with the administration of medications via enteral tubes in adults. Nursing interventions and considerations related to medication administration included form of medication, verifying tube placement before administration, methods used to give medication, methods used to flush tubes, maintenance of tube patency and specific practices to prevent possible complications related to the administration of enteral medications. Search strategy  The following databases were searched for literature reported in English only: CINAHL, MEDLINE, The Cochrane Library, Current Contents/All Editions, EMBASE, Australasian Medical Index and PsychINFO. There was no date restriction applied. In addition, the reference lists of all included

  16. Transcranial direct current stimulation reduces food-craving and measures of hyperphagia behavior in participants with Prader-Willi syndrome.

    Science.gov (United States)

    Bravo, Gabriela L; Poje, Albert B; Perissinotti, Iago; Marcondes, Bianca F; Villamar, Mauricio F; Manzardo, Ann M; Luque, Laura; LePage, Jean F; Stafford, Diane; Fregni, Felipe; Butler, Merlin G

    2016-03-01

    Prader-Willi syndrome (PWS) is a neurodevelopmental genetic disorder characterized by intellectual disabilities and insatiable appetite with compulsive eating leading to severe obesity with detrimental health consequences. Transcranial direct current stimulation (tDCS) has been shown to modulate decision-making and cue-induced food craving in healthy adults. We conducted a pilot double blind, sham-controlled, multicenter study of tDCS modulation of food drive and craving in 10 adult PWS participants, 11 adult obese (OB) and 11 adult healthy-weight control (HWC) subjects. PWS and OB subjects received five consecutive daily sessions of active or sham tDCS over the right dorsolateral prefrontal cortex (DLPFC), while HWC received a single sham and active tDCS in a crossover design. Standardized psychometric instruments assessed food craving, drive and hyperphagia by self-report and caregiver assessment over 30 days. Robust baseline differences were observed in severity scores for the Three-Factor Eating Questionnaire (TFEQ) and Dykens Hyperphagia Questionnaire (DHQ) for PWS compared to HWC while obese participants were more similar to HWC. Active tDCS stimulation in PWS was associated with a significant change from baseline in TFEQ Disinhibition (Factor II) (Ƶ = 1.9, P food drive and behaviors impacting hyperphagia in PWS. Transcranial direct current stimulation may represent a straight-forward, low risk and low cost method to improve care, management and quality of life in PWS. © 2015 Wiley Periodicals, Inc.

  17. Role of Motorcycle Running Lights in Reducing Motorcycle Crashes during Daytime; A Review of the Current Literature

    Science.gov (United States)

    Davoodi, Seyed Rasoul; Hossayni, Seyed Mohamad

    2015-01-01

    In comparison to other transportation modes, riding motorcycle is prone to accidents. Motorcyclists are more exposed to physical injury than the car drivers. Many multi-vehicle motorcycles crashes occur, there is right-of- way violation takes place in which another vehicle turns in fronts of a motorcycle, or a sudden cross of path of an on-coming motorcycle. One main factor which leads to high rate of motorcycle crashes is lack of conspicuity of motorcycles by other road users especially during day time traffic. This paper highlights previous studies on the implementation of motorcycle DRLs, focusing on the efficacy of the DRLs to improve motorcycle conspicuity. This paper reviews the impacts of DRL by motorcyclists on multi-vehicle motorcycle crash. The three categories of effects of motorcycle DRLs were reviewed. All literature, supporting that operating headlights during daytime appears to be an influential and effective approach to reduce rate of collision by improving motorcycle’s conspicuity in traffic. The motorcycle DRLs managed to reduce about 4 to 20% of motorcycle crash risk. This paper also recommends that motorcycle DRLs must be used globally, especially in countries with high motorcycle accidents to improve the safety of the riders as well as their pillion riders. PMID:27162907

  18. Tube welding by the pulsed tig method

    International Nuclear Information System (INIS)

    Dick, N.T.

    1973-01-01

    During the construction of the helical wound boiler pods for the AGR stations at Hartlepool and Heysham, automatic TIG-welding techniques were used. In some cases limited access excluded the use of wire feed techniques and autogenous techniques had to be used. To resolve the problem of excessive concavity which occurred when using constant current autogenous techniques on 14.5 mm OD mild steel tubes of 1.8 mm thickness, pulsed-TIG welding was applied. By modifying the trailing edge of the pulse to produce a crater fill with each pulse, susceptibility to porosity and solidification cracking was reduced. The incorporation of digital counter permitted pulse duration, background duration, and electrode indexing distance to be monitored. (U.K.)

  19. m-YouTube Mobile UI: Video Selection Based on Social Influence

    Science.gov (United States)

    Marcus, Aaron; Perez, Angel

    The ease-of-use of Web-based video-publishing services provided by applications like YouTube has encouraged a new means of asynchronous communication, in which users can post videos not only to make them public for review and criticism, but also as a way to express moods, feelings, or intentions to an ever-growing network of friends. Following the current trend of porting Web applications onto mobile platforms, the authors sought to explore user-interface design issues of a mobile-device-based YouTube, which they call m-YouTube. They first analyzed the elements of success of the current YouTube Web site and observed its functionality. Then, they looked for unsolved issues that could give benefit through information-visualization design for small screens on mobile phones to explore a mobile version of such a product/service. The biggest challenge was to reduce the number of functions and amount information to fit into a mobile phone screen, but still be usable, useful, and appealing within the YouTube context of use and user experience. Borrowing ideas from social research in the area of social influence processes, they made design decisions aiming to help YouTube users to make the decision of what video content to watch and to increase the chances of YouTube authors being evaluated and observed by peers. The paper proposes a means to visualize large amounts of video relevant to YouTube users by using their friendship network as a relevance indicator to help in the decision-making process.

  20. Improving accuracy of ET measurement of LISS nozzle to calandria tube clearance

    International Nuclear Information System (INIS)

    Craig, S.T.; Krause, T.W.; Schankula, J.J.

    2006-01-01

    The AECL Fuel Channel Inspection System (AFCIS) has been used in an in-reactor field trial to successfully measure the clearance between Liquid Injection Shutdown System (LISS) nozzles and calandria tubes. Each measurement over the full length of a channel added only 15 minutes to the on-channel inspection time. No changes were required to the inspection heads. The only equipment changes made were the addition of a Remote Field Eddy Current (RFEC) module to the eddy current instrument, and minor wiring changes, at the instrument, to achieve a RFEC configuration. With the experience gained from the field trial, factors potentially limiting accuracy were identified. These, and other factors, were investigated and are discussed herein. The RFEC probe is delivered inside the pressure tube. Magnetic fields from the RFEC probe extend through the conducting walls of the pressure tube and calandria tube to interact with the LISS nozzle. Data acquired during the field trial showed the LISS nozzle signal is distinct and the signal-to-noise ratio is very favourable. Nevertheless, comparison of the RFEC measurements to a visual examination, made during the same outage, had the RFEC method underestimating the clearance by 2.5 mm on average. By way of laboratory tests, the following factors were investigated as potential sources of error: resistivity and geometry of LISS nozzle reference/calibration pieces, pressure-tube wall thickness, diameter and resistivity variations, pressure-tube to calandria-tube gap, and radial offsets of the probe within the pressure-tube. The sensitivity to these various noise sources was established. A model, based on fundamental electromagnetic principles, was developed and was used to normalize the effects of LISS nozzle conductivity and geometry. This enabled compensation for various sources of error, and made it possible to produce a correction factor for the field trial data, reducing the average difference from the visual inspection of LISS

  1. Step-and-shoot prospectively ECG-gated vs. retrospectively ECG-gated with tube current modulation coronary CT angiography using 128-slice MDCT patients with chest pain: diagnostic performance and radiation dose

    International Nuclear Information System (INIS)

    Kim, Jeong Su; Choo, Ki Seok; Jeong, Dong Wook

    2011-01-01

    Background With increasing awareness for radiation exposure, the study of diagnostic accuracy of coronary CT angiography (CCTA) with low radiation dose techniques is mandatory to both radiologist and clinician. Purpose To compare diagnostic performance and effective radiation dose between step-and-shoot prospectively ECG-gated and retrospectively ECG-gated with tube current modulation (TCM) CCTA using 128-slice multidetector computed tomography (MDCT). Material and Methods We retrospectively evaluated 60 patients who underwent CCTA with either of two different low-dose techniques using 128-slice MDCT (23 patients for step-and shoot-prospectively ECG-gated and 37 patients for retrospectively ECG-gated with TCM CCTA) followed by conventional coronary angiography. All coronary arteries and all segments thereof, except anatomical variants or small size (< 1.5 mm) ones, were included in analysis. Results In per-segment analysis, sensitivity, specificity, positive predictive value, and negative predictive value were 91/96%, 95/94%, 75/73%, and 98/99% for step-and-shoot prospectively ECG-gated and retrospectively ECG gated with TCM CCTA, respectively, relative to conventional coronary angiography. Effective radiation dose were 1.75 ± 0.83 mSv, 4.91 ± 1.71 mSv in the step-and-shoot prospectively ECG-gated and retrospectively ECG-gated with TCM CCTA groups, respectively. Conclusion The two low-radiation dose CCTA techniques using 128-slice MDCT yields comparable diagnostic performance for coronary artery disease in symptomatic patients with low heart rates

  2. Current issues and ways to reduce the negative impact of environment increased concentrations of Radon (222Rn)

    International Nuclear Information System (INIS)

    Coretchi, Liubov; Bahnarel, Ion; Apostol, Ion; Virlan, Serghei

    2012-01-01

    (This study was conducted to review the latest research in radon problem carried out by scientists of Moldova, the 13 EU countries and the USA, and relevant international organizations. Particular attention was paid to contradictions between energy efficiency measures and these of mitigation of 222 Rn negative impact on human health. The main proposals developed were focused on the need for a National Radon Strategy (NRS) and a National Action Plan (NAP) for NRS implementation. Both NRS and NAP has to be correlated with other national policies, such as Smoking Reducing or Energy Efficiency. Development of a Radon Database including a map of radon concentrations, as well as a set of requirements for new housing construction, would be among the main components of NAP. (authors)

  3. Analysis and Design of a Maglev Permanent Magnet Synchronous Linear Motor to Reduce Additional Torque in dq Current Control

    Directory of Open Access Journals (Sweden)

    Feng Xing

    2018-03-01

    Full Text Available The maglev linear motor has three degrees of motion freedom, which are respectively realized by the thrust force in the x-axis, the levitation force in the z-axis and the torque around the y-axis. Both the thrust force and levitation force can be seen as the sum of the forces on the three windings. The resultant thrust force and resultant levitation force are independently controlled by d-axis current and q-axis current respectively. Thus, the commonly used dq transformation control strategy is suitable for realizing the control of the resultant force, either thrust force and levitation force. However, the forces on the three windings also generate additional torque because they do not pass the mover mass center. To realize the maglev system high-precision control, a maglev linear motor with a new structure is proposed in this paper to decrease this torque. First, the electromagnetic model of the motor can be deduced through the Lorenz force formula. Second, the analytic method and finite element method are used to explore the reason of this additional torque and what factors affect its change trend. Furthermore, a maglev linear motor with a new structure is proposed, with two sets of 90 degrees shifted winding designed on the mover. Under such a structure, the mover position dependent periodic part of the additional torque can be offset. Finally, the theoretical analysis is validated by the simulation result that the additionally generated rotating torque can be offset with little fluctuation in the proposed new-structure maglev linear motor. Moreover, the control system is built in MATLAB/Simulink, which shows that it has small thrust ripple and high-precision performance.

  4. Categorising YouTube

    DEFF Research Database (Denmark)

    Simonsen, Thomas Mosebo

    2011-01-01

    This article provides a genre analytical approach to creating a typology of the User Generated Content (UGC) of YouTube. The article investigates the construction of navigation processes on the YouTube website. It suggests a pragmatic genre approach that is expanded through a focus on YouTube......’s technological affordances. Through an analysis of the different pragmatic contexts of YouTube, it is argued that a taxonomic understanding of YouTube must be analysed in regards to the vacillation of a user-driven bottom-up folksonomy and a hierarchical browsing system that emphasises a culture of competition...... and which favours the already popular content of YouTube. With this taxonomic approach, the UGC videos are registered and analysed in terms of empirically based observations. The article identifies various UGC categories and their principal characteristics. Furthermore, general tendencies of the UGC within...

  5. Steam generator tube performance

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1983-08-01

    A review of the performance of steam generator tubes in 110 water-cooled nuclear power reactors showed that tubes were plugged at 46 (42 percent) of the reactors. The number of tubes removed from service increased from 1900 (0.14 percent) in 1980 to 4692 (0.30 percent) in 1981. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that used all-volatile treatment since start-up. At one reactor a large number of degraded tubes were repaired by sleeving which is expected to become an important method of tube repair in the future

  6. Rectangular drift tube characteristics

    International Nuclear Information System (INIS)

    Denisov, D.S.; Musienko, Yu.V.

    1985-01-01

    Results on the study of the characteristics of a 50 x 100 mm aluminium drift tube are presented. The tube was filled with argon-methane and argon-isobutane mixtures. With 16 per cent methane concentration the largest deviation from a linear relation between the drift time and the drift path over 50 mm is less than 2 mm. The tube filled with argon-isobutane mixture is capable of operating in a limited streamer mode

  7. Categorising YouTube

    OpenAIRE

    Simonsen, Thomas Mosebo

    2011-01-01

    This article provides a genre analytical approach to creating a typology of the User Generated Content (UGC) of YouTube. The article investigates the construction of navigation processes on the YouTube website. It suggests a pragmatic genre approach that is expanded through a focus on YouTube’s technological affordances. Through an analysis of the different pragmatic contexts of YouTube, it is argued that a taxonomic understanding of YouTube must be analysed in regards to the vacillation of a...

  8. Pressure tube reactor

    International Nuclear Information System (INIS)

    Susuki, Akira; Murata, Shigeto; Minato, Akihiko.

    1993-01-01

    In a pressure tube reactor, a reactor core is constituted by arranging more than two units of a minimum unit combination of a moderator sealing pipe containing a calandria tube having moderators there between and a calandria tube and moderators. The upper header and a lower header of the calandria tank containing moderators are communicated by way of the moderator sealing tube. Further, a gravitationally dropping mechanism is disposed for injecting neutron absorbing liquid to a calandria gas injection portion. A ratio between a moderator volume and a fuel volume is defined as a function of the inner diameter of the moderator sealing tube, the outer diameter of the calandria tube and the diameter of fuel pellets, and has no influence to intervals of a pressure tube lattice. The interval of the pressure tube lattice is enlarged without increasing the size of the pressure tube, to improve production efficiency of the reactor and set a coolant void coefficient more negative, thereby enabling to improve self controllability and safety. Further, the reactor scram can be conducted by injecting neutron absorbing liquid. (N.H.)

  9. Heated Tube Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Heated Tube Facility at NASA GRC investigates cooling issues by simulating conditions characteristic of rocket engine thrust chambers and high speed airbreathing...

  10. Steam generator tube performance