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Sample records for waves guide cns

  1. Electromagnetic ultrasonic guided waves

    CERN Document Server

    Huang, Songling; Li, Weibin; Wang, Qing

    2016-01-01

    This book introduces the fundamental theory of electromagnetic ultrasonic guided waves, together with its applications. It includes the dispersion characteristics and matching theory of guided waves; the mechanism of production and theoretical model of electromagnetic ultrasonic guided waves; the effect mechanism between guided waves and defects; the simulation method for the entire process of electromagnetic ultrasonic guided wave propagation; electromagnetic ultrasonic thickness measurement; pipeline axial guided wave defect detection; and electromagnetic ultrasonic guided wave detection of gas pipeline cracks. This theory and findings on applications draw on the author’s intensive research over the past eight years. The book can be used for nondestructive testing technology and as an engineering reference work. The specific implementation of the electromagnetic ultrasonic guided wave system presented here will also be of value for other nondestructive test developers.

  2. Guided acoustic wave inspection system

    Science.gov (United States)

    Chinn, Diane J.

    2004-10-05

    A system for inspecting a conduit for undesirable characteristics. A transducer system induces guided acoustic waves onto said conduit. The transducer system detects the undesirable characteristics of the conduit by receiving guided acoustic waves that contain information about the undesirable characteristics. The conduit has at least two sides and the transducer system utilizes flexural modes of propagation to provide inspection using access from only the one side of the conduit. Cracking is detected with pulse-echo testing using one transducer to both send and receive the guided acoustic waves. Thinning is detected in through-transmission testing where one transducer sends and another transducer receives the guided acoustic waves.

  3. Guided-Wave Optical Biosensors

    Science.gov (United States)

    Passaro, Vittorio M. N.; Dell'Olio, Francesco; Casamassima, Biagio; De Leonardis, Francesco

    2007-01-01

    Guided-wave optical biosensors are reviewed in this paper. Advantages related to optical technologies are presented and integrated architectures are investigated in detail. Main classes of bio receptors and the most attractive optical transduction mechanisms are discussed. The possibility to use Mach-Zehnder and Young interferometers, microdisk and microring resonators, surface plasmon resonance, hollow and antiresonant waveguides, and Bragg gratings to realize very sensitive and selective, ultra-compact and fast biosensors is discussed. Finally, CMOS-compatible technologies are proved to be the most attractive for fabrication of guided-wave photonic biosensors.

  4. Electron wind in strong wave guide fields

    Science.gov (United States)

    Krienen, F.

    1985-03-01

    The X-ray activity observed near highly powered waveguide structures is usually caused by local electric discharges originating from discontinuities such as couplers, tuners or bends. In traveling waves electrons move in the direction of the power flow. Seed electrons can multipactor in a traveling wave, the moving charge pattern is different from the multipactor in a resonant structure and is self-extinguishing. The charge density in the wave guide will modify impedance and propagation constant of the wave guide. The radiation level inside the output wave guide of the SLAC, 50 MW, S-band, klystron is estimated. Possible contributions of radiation to window failure are discussed.

  5. Recent Ultrasonic Guided Wave Inspection Development Efforts

    International Nuclear Information System (INIS)

    Rose, Joseph L.; Tittmann, Bernhard R.

    2001-01-01

    The recognition of such natural wave guides as plates, rods, hollow cylinders, multi-layer structures or simply an interface between two materials combined with an increased understanding of the physics and wave mechanics of guided wave propagation has led to a significant increase in the number of guided wave inspection applications being developed each year. Of primary attention Is the ability to inspect partially hidden structures, hard to access areas, and treated or insulated structures. An introduction to some physical consideration of guided waves followed by some sample problem descriptions in pipe, ice detection, fouling detection in the foods industry, aircraft, tar coated structures and acoustic microscopy is presented in this paper. A sample problem in Boundary Element Modeling is also presented to illustrate the move in guided wave analysis beyond detection and location analysis to quantification

  6. Study on guided waves in semiconductor lasers

    International Nuclear Information System (INIS)

    Pudensi, M.A.A.

    1980-01-01

    In This work we studied the guided waves in semiconductor lasers. In the first part we carried on the experimental measurements on lasers with stripe nonorthogonal to the mirrors. In the second part we developed a matrix method for the study of propagation and reflection of guided waves in lasers. (author) [pt

  7. Ultrasonic guided waves in eccentric annular pipes

    International Nuclear Information System (INIS)

    Pattanayak, Roson Kumar; Balasubramaniam, Krishnan; Rajagopal, Prabhu

    2014-01-01

    This paper studies the feasibility of using ultrasonic guided waves to rapidly inspect tubes and pipes for possible eccentricity. While guided waves are well established in the long range inspection of structures such as pipes and plates, studies for more complex cross sections are limited and analytical solutions are often difficult to obtain. Recent developments have made the Semi Analytical Finite Element (SAFE) method widely accessible for researchers to study guided wave properties in complex structures. Here the SAFE method is used to study the effect of eccentricity on the modal structures and velocities of lower order guided wave modes in thin pipes of diameters typically of interest to the industry. Results are validated using experiments. The paper demonstrates that even a small eccentricity in the pipe can strongly affect guided wave mode structures and velocities and hence shows potential for pipe eccentricity inspection

  8. Subduction zone guided waves in Northern Chile

    Science.gov (United States)

    Garth, Thomas; Rietbrock, Andreas

    2016-04-01

    Guided wave dispersion is observed in subduction zones as high frequency energy is retained and delayed by low velocity structure in the subducting slab, while lower frequency energy is able to travel at the faster velocities associated with the surrounding mantle material. As subduction zone guided waves spend longer interacting with the low velocity structure of the slab than any other seismic phase, they have a unique capability to resolve these low velocity structures. In Northern Chile, guided wave arrivals are clearly observed on two stations in the Chilean fore-arc on permanent stations of the IPOC network. High frequency (> 5 Hz) P-wave arrivals are delayed by approximately 2 seconds compared to the low frequency (young subducting lithosphere also has the potential to carry much larger amounts of water to the mantle than has previously been appreciated.

  9. Guided Circumferential Waves in Layered Poroelastic Cylinders

    Directory of Open Access Journals (Sweden)

    Shah S.A.

    2016-12-01

    Full Text Available The present paper investigates the propagation of time harmonic circumferential waves in a two-dimensional hollow poroelastic cylinder with an inner shaft (shaft-bearing assembly. The hollow poroelastic cylinder and inner shaft are assumed to be infinite in axial direction. The outer surface of the cylinder is stress free and at the interface, between the inner shaft and the outer cylinder, it is assumed to be free sliding and the interfacial shear stresses are zero, also the normal stress and radial displacements are continuous. The frequency equation of guided circumferential waves for a permeable and an impermeable surface is obtained. When the angular wave number vanish the frequency equation of guided circumferential waves for a permeable and an impermeable surface degenerates and the dilatational and shear waves are uncoupled. Shear waves are independent of the nature of surface. The frequency equation of a permeable and an impermeable surface for bore-piston assembly is obtained as a particular case of the model under consideration when the outer radius of the hollow poroelastic cylinder tends to infinity. Results of previous studies are obtained as a particular case of the present study. Nondimensional frequency as a function of wave number is presented graphically for two types of models and discussed. Numerical results show that, in general, the first modes are linear for permeable and impermeable surfaces and the frequency of a permeable surface is more than that of an impermeable surface.

  10. Guided ionization waves: Theory and experiments

    International Nuclear Information System (INIS)

    Lu, X.; Naidis, G.V.; Laroussi, M.; Ostrikov, K.

    2014-01-01

    This review focuses on one of the fundamental phenomena that occur upon application of sufficiently strong electric fields to gases, namely the formation and propagation of ionization waves–streamers. The dynamics of streamers is controlled by strongly nonlinear coupling, in localized streamer tip regions, between enhanced (due to charge separation) electric field and ionization and transport of charged species in the enhanced field. Streamers appear in nature (as initial stages of sparks and lightning, as huge structures—sprites above thunderclouds), and are also found in numerous technological applications of electrical discharges. Here we discuss the fundamental physics of the guided streamer-like structures—plasma bullets which are produced in cold atmospheric-pressure plasma jets. Plasma bullets are guided ionization waves moving in a thin column of a jet of plasma forming gases (e.g., He or Ar) expanding into ambient air. In contrast to streamers in a free (unbounded) space that propagate in a stochastic manner and often branch, guided ionization waves are repetitive and highly-reproducible and propagate along the same path—the jet axis. This property of guided streamers, in comparison with streamers in a free space, enables many advanced time-resolved experimental studies of ionization waves with nanosecond precision. In particular, experimental studies on manipulation of streamers by external electric fields and streamer interactions are critically examined. This review also introduces the basic theories and recent advances on the experimental and computational studies of guided streamers, in particular related to the propagation dynamics of ionization waves and the various parameters of relevance to plasma streamers. This knowledge is very useful to optimize the efficacy of applications of plasma streamer discharges in various fields ranging from health care and medicine to materials science and nanotechnology

  11. Wave propagation in plasma-filled wave-guide

    International Nuclear Information System (INIS)

    Leprince, Philippe

    1966-01-01

    This research thesis reports the study of wave propagation along a plasma column without external magnetic field. The author first present and comment various theoretical results, and dispersion curves plotted for the main modes (particularly, the bipolar mode). He tries to define fundamental magnitudes which characterise a plasma-filled wave-guide. He reports the comparison of some experimental results with the previous theoretical results. Based on the study of the bipolar mode, the author develops a method of measurement of plasma column density. In the last part, the author reports the study of the resonance of a plasma-containing cavity. Several resonances are highlighted and new dispersion curves are plotted by using a varying length cavity. He also addresses the coupling of plasma modes with guide modes, and thus indicates the shape of Brillouin diagrams for a plasma-filled wave-guide. Moreover, some phenomena highlighted during plasma column density measurements by using the cavity method could then be explained [fr

  12. Guided wave testing for touch point corrosion

    International Nuclear Information System (INIS)

    Alleyne, David

    2012-01-01

    Guided wave testing (GWT) is established in the petrochemical and related industries, primarily for the detection of corrosion flaws. Touch point corrosion at support positions in pipe-work has become a significant problem within many operating gas, chemical and petro-chemical plants world-wide, particularly as a high proportion of these plants have been operational for many decades. This article demonstrates how GWT using guided waves sent axially along the pipe can be performed for the detection and accurate classification of touchpoint corrosion. The major advantage of GWT methods for the detection of touch point corrosion is its ability to examine several support positions from a single easy to access transducer position. The strategy is then to prioritize or rank the condition of the pipe at the supports by removing those with negligible wall loss from scheduling for further inspection. Guided waves are accurate at detecting and classifying corrosion patches at support positions, but deep pits within such patches are more difficult to accurately identify. Examples using data from routine inspection testing are used to support the development of the methods and testing approaches presented. Recent developments of the interpretation methods, testing procedures and calibration methods have significantly enhanced the capabilities of GWT for this important application.

  13. Guided waves in magnetospheric tubes of enhanced density

    International Nuclear Information System (INIS)

    Maltsev, Yu.P.; Lyatsky, W.B.

    1981-01-01

    Properties of a guided MHD-wave propagating in a magnetic field tube with the plasma density differing from the ambient density are studied. Like the Alven wave this wave propagates along the magnetic field and is connected with the field-aligned currents flowing at the periphery of the oscillating tube. The guided wave is accompanied by the magnetic field compression, nevertheless the wave moves without attenuation. The guided wave velocity is between the Alven velocities inside and outside the oscillating tube. In a tube of elliptical cross-section the propagation velocity depends on the polarization of the wave. (author)

  14. Wireless power transmission using ultrasonic guided waves

    International Nuclear Information System (INIS)

    Kural, A; Pullin, R; Featherston, C; Holford, K; Paget, C

    2011-01-01

    The unavailability of suitable power supply at desired locations is currently an important obstacle in the development of distributed, wireless sensor networks for applications such as structural health monitoring of aircraft. Proposed solutions range from improved batteries to energy harvesting from vibration, temperature gradients and other sources. A novel approach is being investigated at Cardiff University School of Engineering in cooperation with Airbus. It aims to utilise ultrasonic guided Lamb waves to transmit energy through the aircraft skin. A vibration generator is to be placed in a location where electricity supply is readily available. Ultrasonic waves generated by this device will travel through the aircraft structure to a receiver in a remote wireless sensor node. The receiver will convert the mechanical vibration of the ultrasonic waves back to electricity, which will be used to power the sensor node. This paper describes the measurement and modelling of the interference pattern which emerges when Lamb waves are transmitted continuously as in this power transmission application. The discovered features of the pattern, such as a large signal amplitude variation and a relatively high frequency, are presented and their importance for the development of a power transmission system is discussed.

  15. Wireless power transmission using ultrasonic guided waves

    Energy Technology Data Exchange (ETDEWEB)

    Kural, A; Pullin, R; Featherston, C; Holford, K [School of Engineering, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 2AA (United Kingdom); Paget, C, E-mail: kurala@cardiff.ac.uk [Airbus Operations Ltd, New Filton Road, BS99 7AR Bristol (United Kingdom)

    2011-07-19

    The unavailability of suitable power supply at desired locations is currently an important obstacle in the development of distributed, wireless sensor networks for applications such as structural health monitoring of aircraft. Proposed solutions range from improved batteries to energy harvesting from vibration, temperature gradients and other sources. A novel approach is being investigated at Cardiff University School of Engineering in cooperation with Airbus. It aims to utilise ultrasonic guided Lamb waves to transmit energy through the aircraft skin. A vibration generator is to be placed in a location where electricity supply is readily available. Ultrasonic waves generated by this device will travel through the aircraft structure to a receiver in a remote wireless sensor node. The receiver will convert the mechanical vibration of the ultrasonic waves back to electricity, which will be used to power the sensor node. This paper describes the measurement and modelling of the interference pattern which emerges when Lamb waves are transmitted continuously as in this power transmission application. The discovered features of the pattern, such as a large signal amplitude variation and a relatively high frequency, are presented and their importance for the development of a power transmission system is discussed.

  16. Guided wave based structural health monitoring: A review

    International Nuclear Information System (INIS)

    Mitra, Mira; Gopalakrishnan, S

    2016-01-01

    The paper provides a state of the art review of guided wave based structural health monitoring (SHM). First, the fundamental concepts of guided wave propagation and its implementation for SHM is explained. Following sections present the different modeling schemes adopted, developments in the area of transducers for generation, and sensing of wave, signal processing and imaging technique, statistical and machine learning schemes for feature extraction. Next, a section is presented on the recent advancements in nonlinear guided wave for SHM. This is followed by section on Rayleigh and SH waves. Next is a section on real-life implementation of guided wave for industrial problems. The paper, though briefly talks about the early development for completeness, is primarily focussed on the recent progress made in the last decade. The paper ends by discussing and highlighting the future directions and open areas of research in guided wave based SHM. (topical review)

  17. Ultrasonic guided wave for monitoring corrosion of steel bar

    Science.gov (United States)

    Liu, Xi; Qin, Lei; Huang, Bosheng

    2018-01-01

    Steel corrosion of reinforced concrete structures has become a serious problem all over the word. In this paper, the work aims at monitoring steel corrosion using ultrasonic guided wave (UGW). Ultrasonic guided wave monitoring is a dynamic and non-destructive testing technology. The advantages of ultrasonic guided wave monitoring for reinforcement corrosion are real-time, online and continuous. In addition, it can judge the different stages of steel bar corrosion, which achieved non-destructive detection.

  18. Optimal synthesis of tunable elastic wave-guides

    DEFF Research Database (Denmark)

    Evgrafov, Anton; Rupp, Cory J.; Dunn, Martin L.

    2008-01-01

    Topology optimization, or control in the coefficients of partial differential equations, has been successfully utilized for designing wave-guides with precisely tailored functionalities. For many applications it would be desirable to have the possibility of drastically altering the wave...

  19. Guided wave opto-acoustic device

    Science.gov (United States)

    Jarecki, Jr., Robert L.; Rakich, Peter Thomas; Camacho, Ryan; Shin, Heedeuk; Cox, Jonathan Albert; Qiu, Wenjun; Wang, Zheng

    2016-02-23

    The various technologies presented herein relate to various hybrid phononic-photonic waveguide structures that can exhibit nonlinear behavior associated with traveling-wave forward stimulated Brillouin scattering (forward-SBS). The various structures can simultaneously guide photons and phonons in a suspended membrane. By utilizing a suspended membrane, a substrate pathway can be eliminated for loss of phonons that suppresses SBS in conventional silicon-on-insulator (SOI) waveguides. Consequently, forward-SBS nonlinear susceptibilities are achievable at about 3000 times greater than achievable with a conventional waveguide system. Owing to the strong phonon-photon coupling achievable with the various embodiments, potential application for the various embodiments presented herein cover a range of radiofrequency (RF) and photonic signal processing applications. Further, the various embodiments presented herein are applicable to applications operating over a wide bandwidth, e.g. 100 MHz to 50 GHz or more.

  20. Field trials results of guided wave tomography

    International Nuclear Information System (INIS)

    Volker, Arno; Zon, Tim van; Leden, Edwin van der

    2015-01-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Guided wave travel time tomography is a method capable of providing an absolute wall thickness map. This method is currently making the transition from the laboratory to the field. For this purpose a dedicated data acquisition system and special purpose EMAT sensor rings have been developed. The system can be deployed for permanent monitoring and inspections. Field trials have been conducted on various pipes with different diameters, containing either liquid or gas. The main focus has been on pipe supports. The results demonstrate the successful operation of the technology in the field. Expected corrosion damage was clearly visible on the produced results enabling asset owner to make calculated decisions on the pipelines safety, maintenance and operations

  1. Field trials results of guided wave tomography

    Science.gov (United States)

    Volker, Arno; van Zon, Tim; van der Leden, Edwin

    2015-03-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Guided wave travel time tomography is a method capable of providing an absolute wall thickness map. This method is currently making the transition from the laboratory to the field. For this purpose a dedicated data acquisition system and special purpose EMAT sensor rings have been developed. The system can be deployed for permanent monitoring and inspections. Field trials have been conducted on various pipes with different diameters, containing either liquid or gas. The main focus has been on pipe supports. The results demonstrate the successful operation of the technology in the field. Expected corrosion damage was clearly visible on the produced results enabling asset owner to make calculated decisions on the pipelines safety, maintenance and operations.

  2. Guided wave inspection and monitoring of railway track

    CSIR Research Space (South Africa)

    Loveday, PW

    2012-07-01

    Full Text Available of as one-dimensional elastic waveguides, they are natural candidates for guided wave ultrasound, which offers the potential to interrogate a large length of rail from a single position. Guided waves have been proposed as a means of detecting the axial...

  3. Matter-wave scattering and guiding by atomic arrays

    International Nuclear Information System (INIS)

    Vaishnav, J. Y.; Walls, J. D.; Apratim, M.; Heller, E. J.

    2007-01-01

    We investigate the possibility that linear arrays of atoms can guide matter waves, much as fiber optics guide light. We model the atomic line as a quasi-one-dimensional array of s-wave point scatterers embedded in two-dimensions. Our theoretical study reveals how matter-wave guiding arises from the interplay of scattering phenomena with bands and conduction along the array. We discuss the conditions under which a straight or curved array of atoms can guide a beam focused at one end of the array

  4. Directional nonlinear guided wave mixing: Case study of counter-propagating shear horizontal waves

    Science.gov (United States)

    Hasanian, Mostafa; Lissenden, Cliff J.

    2018-04-01

    While much nonlinear ultrasonics research has been conducted on higher harmonic generation, wave mixing provides the potential for sensitive measurements of incipient damage unencumbered by instrumentation nonlinearity. Studies of nonlinear ultrasonic wave mixing, both collinear and noncollinear, for bulk waves have shown the robust capability of wave mixing for early damage detection. One merit of bulk wave mixing lies in their non-dispersive nature, but guided waves enable inspection of otherwise inaccessible material and a variety of mixing options. Co-directional guided wave mixing was studied previously, but arbitrary direction guided wave mixing has not been addressed until recently. Wave vector analysis is applied to study variable mixing angles to find wave mode triplets (two primary waves and a secondary wave) resulting in the phase matching condition. As a case study, counter-propagating Shear Horizontal (SH) guided wave mixing is analyzed. SH wave interactions generate a secondary Lamb wave mode that is readily receivable. Reception of the secondary Lamb wave mode is compared for an angle beam transducer, an air coupled transducer, and a laser Doppler vibrometer (LDV). Results from the angle beam and air coupled transducers are quite consistent, while the LDV measurement is plagued by variability issues.

  5. Guided wave crack detection and size estimation in stiffened structures

    Science.gov (United States)

    Bhuiyan, Md Yeasin; Faisal Haider, Mohammad; Poddar, Banibrata; Giurgiutiu, Victor

    2018-03-01

    Structural health monitoring (SHM) and nondestructive evaluation (NDE) deals with the nondestructive inspection of defects, corrosion, leaks in engineering structures by using ultrasonic guided waves. In the past, simplistic structures were often considered for analyzing the guided wave interaction with the defects. In this study, we focused on more realistic and relatively complicated structure for detecting any defect by using a non-contact sensing approach. A plate with a stiffener was considered for analyzing the guided wave interactions. Piezoelectric wafer active transducers were used to produce excitation in the structures. The excitation generated the multimodal guided waves (aka Lamb waves) that propagate in the plate with stiffener. The presence of stiffener in the plate generated scattered waves. The direct wave and the additional scattered waves from the stiffener were experimentally recorded and studied. These waves were considered as a pristine case in this research. A fine horizontal semi-circular crack was manufactured by using electric discharge machining in the same stiffener. The presence of crack in the stiffener produces additional scattered waves as well as trapped waves. These scattered waves and trapped wave modes from the cracked stiffener were experimentally measured by using a scanning laser Doppler vibrometer (SLDV). These waves were analyzed and compared with that from the pristine case. The analyses suggested that both size and shape of the horizontal crack may be predicted from the pattern of the scattered waves. Different features (reflection, transmission, and mode-conversion) of the scattered wave signals are analyzed. We found direct transmission feature for incident A0 wave mode and modeconversion feature for incident S0 mode are most suitable for detecting the crack in the stiffener. The reflection feature may give a better idea of sizing the crack.

  6. Long-Range Piping Inspection by Ultrasonic Guided Waves

    International Nuclear Information System (INIS)

    Joo, Young Sang; Lim, Sa Hoe; Eom, Heung Seop; Kim, Jae Hee

    2005-01-01

    The ultrasonic guided waves are very promising for the long-range inspection of large structures because they can propagate a long distance along the structures such as plates, shells and pipes. The guided wave inspection could be utilized for an on-line monitoring technique when the transmitting and receiving transducers are positioned at a remote point on the structure. The received signal has the information about the integrity of the monitoring area between the transmitting and receiving transducers. On-line monitoring of a pipe line using an ultrasonic guided wave can detect flaws such as corrosion, erosion and fatigue cracking at an early stage and collect useful information on the flaws. However the guided wave inspection is complicated by the dispersive characteristics for guided waves. The phase and group velocities are a function of the frequency-thickness product. Therefore, the different frequency components of the guided waves will travel at different speeds and the shape of the received signal will changed as it propagates along the pipe. In this study, we analyze the propagation characteristics of guided wave modes in a small diameter pipe of nuclear power plant and select the suitable mode for a long-range inspection. And experiments will be carried out for the practical application of a long-range inspection in a 26m long pipe by using a high-power ultrasonic inspection system

  7. Guided-wave acousto-optics interactions, devices, and applications

    CERN Document Server

    1990-01-01

    The field of integrated- or guided-wave optics has experienced significant and continuous growth since its inception in the late 1960s. There has been a considerable increase in research and development activity in this field worldwide and some significant advances in the realization of working in­ tegrated optic devices and modules have been made in recent years. In fact, there have already been some commercial manufacturing and technical ap­ plications of such devices and modules. The guided-wave-acoustooptics involving Bragg interactions between guided optical waves and surface acoustic waves is one of the areas of in­ tegrated-optics that has reached some degree of scientific and technological maturity. This topical volume is devoted to an in-depth treatment of this emerging branch of science and technology. Presented in this volume are concise treatments on bulk-wave acoustooptics, guided-wave optics, and surface acoustic waves, and detailed studies of guided-wave acoustooptic Bragg diffraction in thr...

  8. Guided ultrasonic wave beam skew in silicon wafers

    Science.gov (United States)

    Pizzolato, Marco; Masserey, Bernard; Robyr, Jean-Luc; Fromme, Paul

    2018-04-01

    In the photovoltaic industry, monocrystalline silicon wafers are employed for solar cells with high conversion efficiency. Micro-cracks induced by the cutting process in the thin wafers can lead to brittle wafer fracture. Guided ultrasonic waves would offer an efficient methodology for the in-process non-destructive testing of wafers to assess micro-crack density. The material anisotropy of the monocrystalline silicon leads to variations of the guided wave characteristics, depending on the propagation direction relative to the crystal orientation. Selective guided ultrasonic wave excitation was achieved using a contact piezoelectric transducer with custom-made wedges for the A0 and S0 Lamb wave modes and a transducer holder to achieve controlled contact pressure and orientation. The out-of-plane component of the guided wave propagation was measured using a non-contact laser interferometer. The phase slowness (velocity) of the two fundamental Lamb wave modes was measured experimentally for varying propagation directions relative to the crystal orientation and found to match theoretical predictions. Significant wave beam skew was observed experimentally, especially for the S0 mode, and investigated from 3D finite element simulations. Good agreement was found with the theoretical predictions based on nominal material properties of the silicon wafer. The important contribution of guided wave beam skewing effects for the non-destructive testing of silicon wafers was demonstrated.

  9. Analysis of waves in the plasma guided by a periodical vane-type slow wave structure

    International Nuclear Information System (INIS)

    Wu, T.J.; Kou, C.S.

    2005-01-01

    In this study, the dispersion relation has been derived to characterize the propagation of the waves in the plasma guided by a periodical vane-type slow wave structure. The plasma is confined by a quartz plate. Results indicate that there are two different waves in this structure. One is the plasma mode that originates from the plasma surface wave propagating along the interface between the plasma and the quartz plate, and the other is the guide mode that originally travels along the vane-type slow wave structure. In contrast to its original slow wave characteristics, the guide mode becomes a fast wave in the low-frequency portion of the passband, and there exists a cut-off frequency for the guide mode. The vane-type guiding structure has been shown to limit the upper frequency of the passband of the plasma mode, compared with that of the plasma surface wave. In addition, the passband of the plasma mode increases with the plasma density while it becomes narrower for the guide mode. The influences of the parameters of the guiding structure and plasma density on the propagation of waves are also presented

  10. Damage identification in composite panels using guided waves

    NARCIS (Netherlands)

    Loendersloot, R.; Moix-Bonet, M.

    2015-01-01

    A methodology for the identification of barely visible impact damage using guided waves on a typical aircraft composite structure is implemented. Delaminations and debondings have been introduced in two stiffened panels by means of impact loads.

  11. Structural damage detection using deep learning of ultrasonic guided waves

    Science.gov (United States)

    Melville, Joseph; Alguri, K. Supreet; Deemer, Chris; Harley, Joel B.

    2018-04-01

    Structural health monitoring using ultrasonic guided waves relies on accurate interpretation of guided wave propagation to distinguish damage state indicators. However, traditional physics based models do not provide an accurate representation, and classic data driven techniques, such as a support vector machine, are too simplistic to capture the complex nature of ultrasonic guide waves. To address this challenge, this paper uses a deep learning interpretation of ultrasonic guided waves to achieve fast, accurate, and automated structural damaged detection. To achieve this, full wavefield scans of thin metal plates are used, half from the undamaged state and half from the damaged state. This data is used to train our deep network to predict the damage state of a plate with 99.98% accuracy given signals from just 10 spatial locations on the plate, as compared to that of a support vector machine (SVM), which achieved a 62% accuracy.

  12. Active Metamaterial Based Ultrasonic Guided Wave Transducer System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — An active and tunable metamaterial phased array transducer for guided wave mode selection with high intensity per driving channel and with dramatically lower modal...

  13. Wave-guide type photo reactor for water purification

    International Nuclear Information System (INIS)

    Nobuaki, Negishi; Feng, He; Sadao, Matsuzawa; Koji, Takeuchi; Kayo, Ohno

    2006-01-01

    A wave-guide type photo-catalytic rod that is consisting of a glass tube with transparent TiO 2 (outside) and an optical wave-guide rod (inside) was designed and examined its performance. A model of polluted water, which contains 100 ppm of toluene or phenol, was taken in a 500 ml of beaker and the performance of this unit was evaluated by the removal rate of pollutants in water under photo-irradiation. Acrylic rod with 6-mm diameter was used as the wave-guide of light. One end of acrylic rod 50 mm had a frosted part or a screw thread for increasing seep out of the light. For the glass tube with transparent TiO 2 , four kinds with different film thickness were prepared by the dip-coating method. The wave-guide type photo-catalytic rods effectively eliminated toluene and phenol and the total amount of intermediates formation was low. (authors)

  14. Mode Identification of Guided Ultrasonic Wave using Time- Frequency Algorithm

    International Nuclear Information System (INIS)

    Yoon, Byung Sik; Yang, Seung Han; Cho, Yong Sang; Kim, Yong Sik; Lee, Hee Jong

    2007-01-01

    The ultrasonic guided waves are waves whose propagation characteristics depend on structural thickness and shape such as those in plates, tubes, rods, and embedded layers. If the angle of incidence or the frequency of sound is adjusted properly, the reflected and refracted energy within the structure will constructively interfere, thereby launching the guided wave. Because these waves penetrate the entire thickness of the tube and propagate parallel to the surface, a large portion of the material can be examined from a single transducer location. The guided ultrasonic wave has various merits like above. But various kind of modes are propagating through the entire thickness, so we don't know the which mode is received. Most of applications are limited from mode selection and mode identification. So the mode identification is very important process for guided ultrasonic inspection application. In this study, various time-frequency analysis methodologies are developed and compared for mode identification tool of guided ultrasonic signal. For this study, a high power tone-burst ultrasonic system set up for the generation and receive of guided waves. And artificial notches were fabricated on the Aluminum plate for the experiment on the mode identification

  15. Ultrasonic guided wave interpretation for structural health inspections

    Science.gov (United States)

    Bingham, Jill Paisley

    Structural Health Management (SHM) combines the use of onboard sensors with artificial intelligence algorithms to automatically identify and monitor structural health issues. A fully integrated approach to SHM systems demands an understanding of the sensor output relative to the structure, along with sophisticated prognostic systems that automatically draw conclusions about structural integrity issues. Ultrasonic guided wave methods allow us to examine the interaction of multimode signals within key structural components. Since they propagate relatively long distances within plate- and shell-like structures, guided waves allow inspection of greater areas with fewer sensors, making this technique attractive for a variety of applications. This dissertation describes the experimental development of automatic guided wave interpretation for three real world applications. Using the guided wave theories for idealized plates we have systematically developed techniques for identifying the mass loading of underwater limpet mines on US Navy ship hulls, characterizing type and bonding of protective coatings on large diameter pipelines, and detecting the thinning effects of corrosion on aluminum aircraft structural stringers. In each of these circumstances the signals received are too complex for interpretation without knowledge of the guided wave physics. We employ a signal processing technique called the Dynamic Wavelet Fingerprint Technique (DFWT) in order to render the guided wave mode information in two-dimensional binary images. The use of wavelets allows us to keep track of both time and scale features from the original signals. With simple image processing we have developed automatic extraction algorithms for features that correspond to the arrival times of the guided wave modes of interest for each of the applications. Due to the dispersive nature of the guided wave modes, the mode arrival times give details of the structure in the propagation path. For further

  16. 3D Guided Wave Motion Analysis on Laminated Composites

    Science.gov (United States)

    Tian, Zhenhua; Leckey, Cara; Yu, Lingyu

    2013-01-01

    Ultrasonic guided waves have proved useful for structural health monitoring (SHM) and nondestructive evaluation (NDE) due to their ability to propagate long distances with less energy loss compared to bulk waves and due to their sensitivity to small defects in the structure. Analysis of actively transmitted ultrasonic signals has long been used to detect and assess damage. However, there remain many challenging tasks for guided wave based SHM due to the complexity involved with propagating guided waves, especially in the case of composite materials. The multimodal nature of the ultrasonic guided waves complicates the related damage analysis. This paper presents results from parallel 3D elastodynamic finite integration technique (EFIT) simulations used to acquire 3D wave motion in the subject laminated carbon fiber reinforced polymer composites. The acquired 3D wave motion is then analyzed by frequency-wavenumber analysis to study the wave propagation and interaction in the composite laminate. The frequency-wavenumber analysis enables the study of individual modes and visualization of mode conversion. Delamination damage has been incorporated into the EFIT model to generate "damaged" data. The potential for damage detection in laminated composites is discussed in the end.

  17. Simulation tools for guided wave based structural health monitoring

    Science.gov (United States)

    Mesnil, Olivier; Imperiale, Alexandre; Demaldent, Edouard; Baronian, Vahan; Chapuis, Bastien

    2018-04-01

    Structural Health Monitoring (SHM) is a thematic derived from Non Destructive Evaluation (NDE) based on the integration of sensors onto or into a structure in order to monitor its health without disturbing its regular operating cycle. Guided wave based SHM relies on the propagation of guided waves in plate-like or extruded structures. Using piezoelectric transducers to generate and receive guided waves is one of the most widely accepted paradigms due to the low cost and low weight of those sensors. A wide range of techniques for flaw detection based on the aforementioned setup is available in the literature but very few of these techniques have found industrial applications yet. A major difficulty comes from the sensitivity of guided waves to a substantial number of parameters such as the temperature or geometrical singularities, making guided wave measurement difficult to analyze. In order to apply guided wave based SHM techniques to a wider spectrum of applications and to transfer those techniques to the industry, the CEA LIST develops novel numerical methods. These methods facilitate the evaluation of the robustness of SHM techniques for multiple applicative cases and ease the analysis of the influence of various parameters, such as sensors positioning or environmental conditions. The first numerical tool is the guided wave module integrated to the commercial software CIVA, relying on a hybrid modal-finite element formulation to compute the guided wave response of perturbations (cavities, flaws…) in extruded structures of arbitrary cross section such as rails or pipes. The second numerical tool is based on the spectral element method [2] and simulates guided waves in both isotropic (metals) and orthotropic (composites) plate like-structures. This tool is designed to match the widely accepted sparse piezoelectric transducer array SHM configuration in which each embedded sensor acts as both emitter and receiver of guided waves. This tool is under development and

  18. Development of an SH Wave Magnetostrictive Transducer Module for Guided Wave Testing of Plate Structures

    International Nuclear Information System (INIS)

    Cho, Seung Hyun; Park, Jae Ha; Kwon Hyu Sang; Ahn, Bong Young; Lee, Seung Seok

    2009-01-01

    Recently much attention has been paid to a guided wave due to its effective applicability to long range and fast inspection of structures. In guided wave based NDE, the appropriate selection of wave modes is one of important factors since the test performance is highly dependent on which mode of guided waves is employed. As far as plate-like structures are concerned, so far, SH guided wave has not been frequently applied compared to Lamb waves, which is mostly caused by the lack of proper and convenient transducers to generate and measure the SH waves. In this investigation, a new small-sized SH guided wave transducer based on magnetostriction is proposed. The present transducer was designed to be modular and be used with shear couplant to avoid the inconvenience of the existing magnetostrictive patch transducers, which comprises the ferromagnetic patch tightly bonded to a structure. The wave transduction mechanism and the detailed configuration of the present transducer are presented. Experimental verification is also conducted on test specimens and the results confirm the good performance of the present transducer module

  19. Development of an SH Wave Magnetostrictive Transducer Module for Guided Wave Testing of Plate Structures

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seung Hyun; Park, Jae Ha; Kwon Hyu Sang; Ahn, Bong Young; Lee, Seung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2009-04-15

    Recently much attention has been paid to a guided wave due to its effective applicability to long range and fast inspection of structures. In guided wave based NDE, the appropriate selection of wave modes is one of important factors since the test performance is highly dependent on which mode of guided waves is employed. As far as plate-like structures are concerned, so far, SH guided wave has not been frequently applied compared to Lamb waves, which is mostly caused by the lack of proper and convenient transducers to generate and measure the SH waves. In this investigation, a new small-sized SH guided wave transducer based on magnetostriction is proposed. The present transducer was designed to be modular and be used with shear couplant to avoid the inconvenience of the existing magnetostrictive patch transducers, which comprises the ferromagnetic patch tightly bonded to a structure. The wave transduction mechanism and the detailed configuration of the present transducer are presented. Experimental verification is also conducted on test specimens and the results confirm the good performance of the present transducer module

  20. Guided propagation of Alfven waves in a toroidal plasma

    International Nuclear Information System (INIS)

    Borg, G.G.; Brennan, M.H.; Cross, R.C.; Giannone, L.; Donnelly, I.J.

    1985-01-01

    Experimental results are presented which show that the Alfven wave is strongly guided by magnetic fields. The experiment was conducted in a Tokamak plasma using a small dipole loop antenna to generate a localised Alfven ray. The ray was observed, with magnetic probes, to propagate as a localised disturbance along the curved lines of the steady magnetic field without significant refraction due to the effects of finite frequency, resistivity or magnetic field gradients. These results agree with theoretical predictions and demonstrate that a localised Alfven wave may be excited, and may propagate, independently of the fast wave, as expected. The implication of these results for the Alfven wave heating scheme is discussed. (author)

  1. Guided propagation of Alfven waves in a toroidal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Borg, G G; Brennan, M H; Cross, R C; Giannone, L.; Donnelly, I J

    1985-10-01

    Experimental results are presented which show that the Alfven wave is strongly guided by magnetic fields. The experiment was conducted in a Tokamak plasma using a small dipole loop antenna to generate a localised Alfven ray. The ray was observed, with magnetic probes, to propagate as a localised disturbance along the curved lines of the steady magnetic field without significant refraction due to the effects of finite frequency, resistivity or magnetic field gradients. These results agree with theoretical predictions and demonstrate that a localised Alfven wave may be excited, and may propagate, independently of the fast wave, as expected. The implication of these results for the Alfven wave heating scheme is discussed.

  2. Signal Processing Effects for Ultrasonic Guided Wave Scanning of Composites

    International Nuclear Information System (INIS)

    Roth, D.J.; Cosgriff, L.M.; Martin, R.E.; Burns, E.A.; Teemer, L.

    2005-01-01

    The goal of this ongoing work is to optimize experimental variables for a guided wave scanning method to obtain the most revealing and accurate images of defect conditions in composite materials. This study focuses on signal processing effects involved in forming guided wave scan images. Signal processing is involved at two basic levels for deriving ultrasonic guided wave scan images. At the primary level, NASA GRC has developed algorithms to extract over 30 parameters from the multimode signal and its power spectral density. At the secondary level, there are many variables for which values must be chosen that affect actual computation of these parameters. In this study, a ceramic matrix composite sample having a delamination is characterized using the ultrasonic guided wave scan method. Energy balance and decay rate parameters of the guided wave at each scan location are calculated to form images. These images are compared with ultrasonic c-scan and thermography images. The effect of the time portion of the waveform processed on image quality is assessed by comparing with images formed using the total waveform acquired

  3. Investigation of guided waves propagation in pipe buried in sand

    International Nuclear Information System (INIS)

    Leinov, Eli; Cawley, Peter; Lowe, Michael J.S.

    2014-01-01

    The inspection of pipelines by guided wave testing is a well-established method for the detection of corrosion defects in pipelines, and is currently used routinely in a variety of industries, e.g. petrochemical and energy. When the method is applied to pipes buried in soil, test ranges tend to be significantly compromised because of attenuation of the waves caused by energy radiating into the soil. Moreover, the variability of soil conditions dictates different attenuation characteristics, which in-turn results in different, unpredictable, test ranges. We investigate experimentally the propagation and attenuation characteristics of guided waves in pipes buried in fine sand using a well characterized full scale experimental apparatus. The apparatus consists of an 8 inch-diameter, 5.6-meters long steel pipe embedded over 3 meters of its length in a rectangular container filled with fine sand, and an air-bladder for the application of overburden pressure. Longitudinal and torsional guided waves are excited in the pipe and recorded using a transducer ring (Guided Ultrasonics Ltd). Acoustic properties of the sand are measured independently in-situ and used to make model predictions of wave behavior in the buried pipe. We present the methodology and the systematic measurements of the guided waves under a range of conditions, including loose and compacted sand. It is found that the application of overburden pressure modifies the compaction of the sand and increases the attenuation, and that the measurement of the acoustic properties of sand allows model prediction of the attenuation of guided waves in buried pipes with a high level of confidence

  4. Corrosion monitoring using high-frequency guided ultrasonic waves

    Science.gov (United States)

    Fromme, Paul

    2014-02-01

    Corrosion develops due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the structural integrity. The nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, guided wave modes were generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted and the wall thickness reduced by consecutive milling of the steel structure. Further measurements were conducted using accelerated corrosion in a salt water bath and the damage severity monitored. From the measured signal change due to the wave mode interference the wall thickness reduction was monitored. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

  5. Corrosion monitoring using high-frequency guided waves

    Science.gov (United States)

    Fromme, P.

    2016-04-01

    Corrosion can develop due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Generalized corrosion leading to wall thickness loss can cause the reduction of the strength and thus degradation of the structural integrity. The monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic wedge transducers with single sided access to the structure, guided wave modes were selectively generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted for wall thickness reduction due to milling of the steel structure. From the measured signal changes due to the wave mode interference the reduced wall thickness was monitored. Good agreement with theoretical predictions was achieved. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

  6. NIKHEF traveling wave monitor: user guide

    International Nuclear Information System (INIS)

    Sluijk, T.

    1984-01-01

    The NIKHEF Travelling Wave Monitor (TWM) is a sensitive, non intercepting device to measure beam displacement. The measurement is independent of the beam intensity. The TWM consists of a waveguide assembly and separate electronics assembly. Specifications are given, as well as instructions for use. (Auth./G.J.P.)

  7. High frequency guided wave propagation in monocrystalline silicon wafers

    OpenAIRE

    Pizzolato, M.; Masserey, B.; Robyr, J. L.; Fromme, P.

    2017-01-01

    Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. The cutting process can introduce micro-cracks in the thin wafers and lead to varying thickness. High frequency guided ultrasonic waves are considered for the structural monitoring of the wafers. The anisotropy of the monocrystalline silicon leads to variations of the wave characteristics, depending on the propagation direction relative to the crystal orientation. Full...

  8. Obtaining thickness profiles from the tomographic inversion of guided wave data

    NARCIS (Netherlands)

    Bloom, J.G.P.; Luiten, E.A.; Volker, A.W.F.

    2009-01-01

    Guided wave tomography is a promising technique for the monitoring of corrosion over large areas. Guided waves have a wave speed mat depends in certain frequency-thickness regimes on the local thickness of the waveguide they follow. Therefore, the travel time of the guided wave over a fixed distance

  9. Distributed feedback guided surface acoustic wave microresonator

    Science.gov (United States)

    Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

    1989-08-01

    Surface acoustic wave resonators have been used in a number of applications: high-Q frequency filtering, very accurate frequency sources, etc. A major disadvantage of conventional resonators is their large dimensions, which makes them inadequate for integrated acoustics applications. In order to overcome these size limitations a new type of microresonator was designed, developed, and tested. In this paper, theoretical calculations and measurements on two kinds of such devices (a corrugated waveguide filter and a microresonator structure) are presented and their possible applications are discussed.

  10. Guided wave inspection and monitoring of railway track

    CSIR Research Space (South Africa)

    Loveday, PW

    2012-04-01

    Full Text Available for guided wave ultrasound, which offers the potential to interrogate a large length of rail from a single position. Continuously welded rail is installed in tension but temperature changes can result in rail buckling if the tension is insufficient or fatigue...

  11. Scanning laser vibrometer measurement of guided waves in rails

    CSIR Research Space (South Africa)

    Loveday, PW

    2012-04-01

    Full Text Available Guided wave based inspection and monitoring systems for railway tracks operate at frequencies where as many as 40 modes of propagation may exist. During the development of such systems it is advantageous to be able to measure the amplitude...

  12. SU-8 Guiding Layer for Love Wave Devices

    Directory of Open Access Journals (Sweden)

    Michael I. Newton

    2007-11-01

    Full Text Available SU-8 is a technologically important photoresist used extensively for thefabrication of microfluidics and MEMS, allowing high aspect ratio structures to beproduced. In this work we report the use of SU-8 as a Love wave sensor guiding layerwhich allows the possibility of integrating a guiding layer with flow cell during fabrication.Devices were fabricated on ST-cut quartz substrates with a single-single finger design suchthat a surface skimming bulk wave (SSBW at 97.4 MHz was excited. SU-8 polymer layerswere successively built up by spin coating and spectra recorded at each stage; showing afrequency decrease with increasing guiding layer thickness. The insertion loss andfrequency dependence as a function of guiding layer thickness was investigated over thefirst Love wave mode. Mass loading sensitivity of the resultant Love wave devices wasinvestigated by deposition of multiple gold layers. Liquid sensing using these devices wasalso demonstrated; water-glycerol mixtures were used to demonstrate sensing of density-viscosity and the physical adsorption and removal of protein was also assessed usingalbumin and fibrinogen as model proteins.

  13. Mechanical guided waves for fuel level monitoring system

    Directory of Open Access Journals (Sweden)

    Tiberiu Adrian SALAORU

    2017-09-01

    Full Text Available The mechanical guided waves have a wide range of applications in many types of equipment and devices. The fuel level is an important parameter which needs to be monitored for a vehicle which can be a space vehicle, an aircraft or any other. For this purpose mechanical guided waves can be used as they have several major advantages over any other methods. There are a wide ultrasonic sensors used for this purpose but in the most cases the mechanical waves are traveling through air or fuel for measuring their level. In general the wave propagation through a single media at a time is utilized. The method described in this work uses the propagation of the mechanical guided waves through two different media in the same time. The propagating media is the container wall and the other is the fuel. One of the advantages of this method is the reduction of the measurement errors when the incident angle to the fuel level surface is different from 90 degree. These situations could occur when the fuel tank is tilted or when the fuel surface is not flat. This measurement method will not be affected by these conditions.

  14. High frequency guided wave propagation in monocrystalline silicon wafers

    Science.gov (United States)

    Pizzolato, Marco; Masserey, Bernard; Robyr, Jean-Luc; Fromme, Paul

    2017-04-01

    Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. The cutting process can introduce micro-cracks in the thin wafers and lead to varying thickness. High frequency guided ultrasonic waves are considered for the structural monitoring of the wafers. The anisotropy of the monocrystalline silicon leads to variations of the wave characteristics, depending on the propagation direction relative to the crystal orientation. Full three-dimensional Finite Element simulations of the guided wave propagation were conducted to visualize and quantify these effects for a line source. The phase velocity (slowness) and skew angle of the two fundamental Lamb wave modes (first anti-symmetric mode A0 and first symmetric mode S0) for varying propagation directions relative to the crystal orientation were measured experimentally. Selective mode excitation was achieved using a contact piezoelectric transducer with a custom-made wedge and holder to achieve a controlled contact pressure. The out-of-plane component of the guided wave propagation was measured using a noncontact laser interferometer. Good agreement was found with the simulation results and theoretical predictions based on nominal material properties of the silicon wafer.

  15. Scattering of guided waves at delaminations in composite plates.

    Science.gov (United States)

    Murat, Bibi I S; Khalili, Pouyan; Fromme, Paul

    2016-06-01

    Carbon fiber laminate composites are increasingly employed for aerospace structures as they offer advantages, such as a good strength to weight ratio. However, impact during the operation and servicing of the aircraft can lead to barely visible and difficult to detect damage. Depending on the severity of the impact, fiber and matrix breakage or delaminations can occur, reducing the load carrying capacity of the structure. Efficient nondestructive testing and structural health monitoring of composite panels can be achieved using guided ultrasonic waves propagating along the structure. The scattering of the A0 Lamb wave mode at delaminations was investigated using a full three-dimensional (3D) finite element (FE) analysis. The influence of the delamination geometry (size and depth) was systematically evaluated. In addition to the depth dependency, a significant influence of the delamination width due to sideways reflection of the guided waves within the delamination area was found. Mixed-mode defects were simulated using a combined model of delamination with localized material degradation. The guided wave scattering at cross-ply composite plates with impact damage was measured experimentally using a non-contact laser interferometer. Good agreement between experiments and FE predictions using the mixed-mode model for an approximation of the impact damage was found.

  16. Mode Identification of Guided Waves in a Curved Pipe

    International Nuclear Information System (INIS)

    Eom, Heung-Seop; Lim, Sa-Hoe; Kim, Jae-Hee

    2006-01-01

    Ultrasonic guided wave technique has been widely employed for the long range inspection of structures such as plates and pipes because it has the ability to propagate over long distances. In the nuclear power field, there recently appeared a need for on-line nondestructive monitoring which can be employed during the operation stage of power plants. As ultrasonic guided waves have shown promise for on-line monitoring of power plants, a lot of work has been done in the institutes and universities on this matter. In the case of detecting defects in simple straight pipes, the dispersion curves obtained from the modeling processes are closely akin to the experimental results. But the modeling of wave propagation in some structures, such as an elbow region of a pipe, is not practical due to elbow echo and unpredictable interface conditions. This paper presents an experimental approach to identify the most dominant modes of guided waves in a curved region of a pipe, which is a key factor in detecting flaws in a pipe

  17. Plasma wave amplitude measurement created by guided laser wakefield

    International Nuclear Information System (INIS)

    Wojda, Franck

    2010-01-01

    The interaction of an intense laser pulse of short duration with a plasma produces a plasma wave with large amplitude in its wake, which is associated with a longitudinal electric field. It can be used to accelerate relativistic electrons injected into the wave to energies in the GeV range over distances of the order of a few centimeters, short compared to acceleration lengths in conventional accelerators. The control of the electron beam characteristics during the acceleration process is fundamental for achieving a usable laser-plasma acceleration stage. The main result of this thesis is the creation and characterization of a plasma wave in a weakly nonlinear regime over a length of several centimeters. Capillary tubes are used to guide the laser beam over these distances, while maintaining a large enough intensity (∼ 10 17 W/cm 2 ). The guided laser beam ionizes the gas in the tube and creates the plasma wave. A diagnostic based on the modification of the laser pulse spectrum was used to determine the amplitude of the plasma wave along the tube. The amplitude of the plasma wave was studied as a function of gas filling pressure, length of the capillary and laser energy. Experimental results are compared; they are in excellent agreement with analytical results and modeling. They show that the electric field associated with the plasma wave is between 1 and 10 GV/m over a length of up to 8 cm. This work has demonstrated the ability to create a controlled plasma wave in a weakly nonlinear regime. (author)

  18. Modelling guided waves in the Alaskan-Aleutian subduction zone

    Science.gov (United States)

    Coulson, Sophie; Garth, Thomas; Reitbrock, Andreas

    2016-04-01

    Subduction zone guided wave arrivals from intermediate depth earthquakes (70-300 km depth) have a huge potential to tell us about the velocity structure of the subducting oceanic crust as it dehydrates at these depths. We see guided waves as the oceanic crust has a slower seismic velocity than the surrounding material, and so high frequency energy is retained and delayed in the crustal material. Lower frequency energy is not retained in this crustal waveguide and so travels at faster velocities of the surrounding material. This gives a unique observation at the surface with low frequency energy arriving before the higher frequencies. We constrain this guided wave dispersion by comparing the waveforms recorded in real subduction zones with simulated waveforms, produced using finite difference full waveform modelling techniques. This method has been used to show that hydrated minerals in the oceanic crust persist to much greater depths than accepted thermal petrological subduction zone models would suggest in Northern Japan (Garth & Rietbrock, 2014a), and South America (Garth & Rietbrock, in prep). These observations also suggest that the subducting oceanic mantle may be highly hydrated at intermediate depth by dipping normal faults (Garth & Rietbrock 2014b). We use this guided wave analysis technique to constrain the velocity structure of the down going ~45 Ma Pacific plate beneath Alaska. Dispersion analysis is primarily carried out on guided wave arrivals recorded on the Alaskan regional seismic network. Earthquake locations from global earthquake catalogues (ISC and PDE) and regional earthquake locations from the AEIC (Alaskan Earthquake Information Centre) catalogue are used to constrain the slab geometry and to identify potentially dispersive events. Dispersed arrivals are seen at stations close to the trench, with high frequency (>2 Hz) arrivals delayed by 2 - 4 seconds. This dispersion is analysed to constrain the velocity and width of the proposed waveguide

  19. Signal characteristics of guided wave for condenser tube of NPP

    International Nuclear Information System (INIS)

    Min, Lee Dong; Hoon, Choi Sang; Yeong, Yang Tae

    2012-01-01

    A Condenser is a large heat exchanger of the shell and tube type. Cooling water enters through the water box, through the tubesheet and into the tubes(about 80,000 tubes/unit). The shell side of the condenser receives steam from the low pressure turbines exhaust. The steam is cooled to a liquid by passing over the tubes where the cooling water is circulated. Because seawater is used as a coolant, condenser tubes are easily damaged. For such a reason, nondestructive testing conducted periodically. But nondestructive testing takes a lot of manpower and time. Guided wave technique can overcome these shortcomings. In this study, we made an effort evaluating a guided wave defect signal

  20. Ultrasonic guided wave inspection of Inconel 625 brazed lap joints

    Science.gov (United States)

    Comot, Pierre; Bocher, Philippe; Belanger, Pierre

    2016-04-01

    The aerospace industry has been investigating the use of brazing for structural joints, as a mean of reducing cost and weight. There therefore is a need for a rapid, robust, and cost-effective non-destructive testing method for evaluating the structural integrity of the joints. The mechanical strength of brazed joints depends mainly on the amount of brittle phases in their microstructure. Ultrasonic guided waves offer the possibility of detecting brittle phases in joints using spatio-temporal measurements. Moreover, they offer the opportunity to inspect complex shape joints. This study focused on the development of a technique based on ultrasonic guided waves for the inspection of Inconel 625 lap joints brazed with BNi-2 filler metal. A finite element model of a lap joint was used to optimize the inspection parameters and assess the feasibility of detecting the amount of brittle phases in the joint. A finite element parametric study simulating the input signal shape, the center frequency, and the excitation direction was performed. The simulations showed that the ultrasonic guided wave energy transmitted through, and reflected from, the joints was proportional to the amount of brittle phases in the joint.

  1. Investigation on ultrasonic guided waves propagation in elbow pipe

    International Nuclear Information System (INIS)

    Qi, Minxin; Zhou, Shaoping; Ni, Jing; Li, Yong

    2016-01-01

    Pipeline plays an indispensable role in process industries, whose structural integrity is of great significance for the safe production. In this paper, the axial crack-like defects in 90° elbows are inspected by using the T (0, 1) mode guided waves. The detection sensitivity for different defect locations is firstly investigated by guided waves experimentally. The propagation of guided waves in the bent pipe is then simulated by using finite element method. The results show that the rates of T (0, 1) mode passing through elbow correlate strongly with the excitation frequency. Less mode conversion is generated at the frequency of 38 kHz when passing through the elbow, while most of energy converted into F (1, 2) mode at the frequency of 75 kHz. The crack in different locations of the elbow can affect the rates of mode conversion. It can be found that the crack in the middle of the elbow inhibits mode conversion and shares the highest detection sensitivity, while the crack in the extrados of elbow causes more mode conversion.

  2. Application of RMS for damage detection by guided elastic waves

    Energy Technology Data Exchange (ETDEWEB)

    Radzienski, M; Dolinski, L; Krawczuk, M [Gdansk University of Technology, Faculty of Electrical and Control Engineering, Narutowicza 11/12, 80-952 Gdansk (Poland); Zak, A; Ostachowicz, W, E-mail: Maciej.Radzienski@gmail.com [Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-952 Gdansk (Poland)

    2011-07-19

    This paper presents certain results of an experimental study related with a damage detection in structural elements based on deviations in guided elastic wave propagation patterns. In order to excite guided elastic waves within specimens tested piezoelectric transducers have been applied. As excitation signals 5 sine cycles modulated by Hanning window have been used. Propagation of guided elastic waves has been monitored by a scanning Doppler laser vibrometer. The time signals recorded during measurement have been utilised to calculate the values of RMS. It has turned out that the values of RMS differed significantly in damaged areas from the values calculated for the healthy ones. In this way it has become possible to pinpoint precisely the locations of damage over the entire measured surface. All experimental investigations have been carried out for thin aluminium or composite plates. Damage has been simulated by a small additional mass attached on the plate surface or by a narrow notch cut. It has been shown that proposed method allows one to localise damage of various shapes and sizes within structural elements over the whole area under investigation.

  3. Application of RMS for damage detection by guided elastic waves

    Science.gov (United States)

    Radzieński, M.; Doliński, Ł.; Krawczuk, M.; dot Zak, A.; Ostachowicz, W.

    2011-07-01

    This paper presents certain results of an experimental study related with a damage detection in structural elements based on deviations in guided elastic wave propagation patterns. In order to excite guided elastic waves within specimens tested piezoelectric transducers have been applied. As excitation signals 5 sine cycles modulated by Hanning window have been used. Propagation of guided elastic waves has been monitored by a scanning Doppler laser vibrometer. The time signals recorded during measurement have been utilised to calculate the values of RMS. It has turned out that the values of RMS differed significantly in damaged areas from the values calculated for the healthy ones. In this way it has become possible to pinpoint precisely the locations of damage over the entire measured surface. All experimental investigations have been carried out for thin aluminium or composite plates. Damage has been simulated by a small additional mass attached on the plate surface or by a narrow notch cut. It has been shown that proposed method allows one to localise damage of various shapes and sizes within structural elements over the whole area under investigation.

  4. Guided Wave Delamination Detection and Quantification With Wavefield Data Analysis

    Science.gov (United States)

    Tian, Zhenhua; Campbell Leckey, Cara A.; Seebo, Jeffrey P.; Yu, Lingyu

    2014-01-01

    Unexpected damage can occur in aerospace composites due to impact events or material stress during off-nominal loading events. In particular, laminated composites are susceptible to delamination damage due to weak transverse tensile and inter-laminar shear strengths. Developments of reliable and quantitative techniques to detect delamination damage in laminated composites are imperative for safe and functional optimally-designed next-generation composite structures. In this paper, we investigate guided wave interactions with delamination damage and develop quantification algorithms by using wavefield data analysis. The trapped guided waves in the delamination region are observed from the wavefield data and further quantitatively interpreted by using different wavenumber analysis methods. The frequency-wavenumber representation of the wavefield shows that new wavenumbers are present and correlate to trapped waves in the damage region. These new wavenumbers are used to detect and quantify the delamination damage through the wavenumber analysis, which can show how the wavenumber changes as a function of wave propagation distance. The location and spatial duration of the new wavenumbers can be identified, providing a useful means not only for detecting the presence of delamination damage but also allowing for estimation of the delamination size. Our method has been applied to detect and quantify real delamination damage with complex geometry (grown using a quasi-static indentation technique). The detection and quantification results show the location, size, and shape of the delamination damage.

  5. Guided waves and ultrasonic characterization of three-dimensional composites

    Science.gov (United States)

    Leymarie, Nicolas; Baste, Stéphane

    2000-05-01

    Ultrasonic NDE of anisotropic media appears nowadays as one of the best experimental approaches in studying mechanical properties. A complete identification of stiffness tensor can be performed with phase velocity measurements of obliquely incidence ultrasonic bulk waves from water onto a plate. The medium considered, however, has to be homogeneous with respect to wavelength used. In the case of 3D-composites, textures scales may reach one millimeter and their cut-off frequency is less than MHz. The dispersion curves observed in the considered range of frequencies are often very close and sometimes may be overlapped. Experimental studies show complex signals, which are due to a combination of both bulk and guided waves. Wave-speed measurements of the bulk wave and its detection become unreliable with classical techniques of signal processing (simple time or spectral analysis). Moreover, even if the coupled time-frequency analysis with wavelet transforms allows a better interpretation of the signal, the time delay estimation for the bulk wave and so the characterization of the material remains uncertain. To understand blended signals more accurately, different analytical and numerical models are proposed to show the advantages and disadvantages of methods used in NDE.

  6. Cost estimates to guide manufacturing of composite waved beam

    International Nuclear Information System (INIS)

    Ye Jinrui; Zhang Boming; Qi Haiming

    2009-01-01

    A cost estimation model on the basis of manufacturing process has been presented. In the model, the effects of the material, labor, tool and equipment were discussed, and the corresponding formulas were provided. A method of selecting estimation variables has been provided based on a case study of composite waved beam using autoclave cure. The model parameters related to the process time estimation of the lay-up procedure were analyzed and modified for different part configurations. The result shows that there is little error while comparing the estimated process time with the practical one. The model is verified to be applicable to guide the design and manufacturing of the composite material

  7. Laser vibrometer measurement of guided wave modes in rail track

    CSIR Research Space (South Africa)

    Loveday, PW

    2014-11-01

    Full Text Available ) in the laboratory and on an operational rail track (with S-4 60-SAR profile) and example results are presented in this section. The measurements 5 were performed using a Polytec PSV-400-M2-20 high frequency scanning vibrometer 6 equipped with the VD-09 velocity...Hz on operational rail track and to identify the modes that are capable of 16 propagating large distances. 17 18 KEYWORDS: Semi-analytical finite element method; modes of guided wave 19 propagation; laser vibrometer measurement; rail track 20 PACs...

  8. Guided wave photonics fundamentals and applications with Matlab

    CERN Document Server

    Binh, Le Nguyen

    2012-01-01

    IntroductionHistorical Overview of Integrated Optics and PhotonicsWhy Analysis of Optical Guided-wave Devices?Principal ObjectivesChapters OverviewSingle Mode Planar Optical WaveguidesFormation of Planar Single Mode Waveguide ProblemsApproximate Analytical Methods of SolutionAPPENDIX A: Maxwell Equations in Dielectric MediaAPPENDIX B: Exact Analysis of Clad-linear Optical WaveguidesAPPENDIX C: Wentzel-Kramers-Brilluoin Method, Turning Points and Connection FormulaeAPPENDIX D: Design and Simulation of Planar Optical Waveguides3D Integrated Optical WaveguidesMarcatili's Method| Effective Index M

  9. In Situ Guided Wave Structural Health Monitoring System

    Science.gov (United States)

    Zhao, George; Tittmann, Bernhard R.

    2011-01-01

    Aircraft engine rotating equipment operates at high temperatures and stresses. Noninvasive inspection of microcracks in those components poses a challenge for nondestructive evaluation. A low-cost, low-profile, high-temperature ultrasonic guided wave sensor was developed that detects cracks in situ. The transducer design provides nondestructive evaluation of structures and materials. A key feature of the sensor is that it withstands high temperatures and excites strong surface wave energy to inspect surface and subsurface cracks. The sol-gel bismuth titanate-based surface acoustic wave (SAW) sensor can generate efficient SAWs for crack inspection. The sensor is very thin (submillimeter) and can generate surface waves up to 540 C. Finite element analysis of the SAW transducer design was performed to predict the sensor behavior, and experimental studies confirmed the results. The sensor can be implemented on structures of various shapes. With a spray-coating process, the sensor can be applied to the surface of large curvatures. It has minimal effect on airflow or rotating equipment imbalance, and provides good sensitivity.

  10. A Study on Techniques for Focusing Circumferential Array Guided Waves for Long Range Inspection of Pipes

    International Nuclear Information System (INIS)

    Kang, To; Kim, Hak Joon; Song, Sung Jin; Cho, Young Do; Lee, Dong Hoon; Cho, Hyun Joon

    2009-01-01

    Ultrasonic guided waves have been widely utilized for long range inspection of structures. Especially, development of array guided waves techniques and its application for long range gas pipe lines(length of from hundreds meters to few km) were getting increased. In this study, focusing algorithm for array guided waves was developed in order to improve long range inspectability and accuracy of the array guided waves techniques for long range inspection of gas pipes, and performance of the developed techniques was verified by experiments using the developed array guided wave system. As a result, S/N ratio of array guided wave signals obtained with the focusing algorithm was increased higher than that of signals without focusing algorithm

  11. Parametric study of guided waves dispersion curves for composite plates

    Science.gov (United States)

    Predoi, Mihai Valentin; Petre, Cristian Cǎtǎlin; Kettani, Mounsif Ech Cherif El; Leduc, Damien

    2018-02-01

    Nondestructive testing of composite panels benefit from the relatively long range propagation of guided waves in sandwich structures. The guided waves are sensitive to delamination, air bubbles inclusions and cracks and can thus bring information about hidden defects in the composite panel. The preliminary data in all such inspections is represented by the dispersion curves, representing the dependency of the phase/group velocity on the frequency for the propagating modes. In fact, all modes are more or less attenuated, so it is even more important to compute the dispersion curves, which provide also the modal attenuation as function of frequency. Another important aspect is the sensitivity of the dispersion curves on each of the elastic constant of the composite, which are orthotropic in most cases. All these aspects are investigated in the present work, based on our specially developed finite element numerical model implemented in Comsol, which has several advantages over existing methods. The dispersion curves and modal displacements are computed for an example of composite plate. Comparison with literature data validates the accuracy of our results.

  12. 1-D profiling using highly dispersive guided waves

    International Nuclear Information System (INIS)

    Volker, Arno; Zon, Tim van

    2014-01-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently, inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness of steel pipes. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pitch-catch configuration at the 12 o'clock position using highly dispersive guided waves. After dispersion correction the data collapses to a short pulse, any residual dispersion indicates wall loss. The phase spectrum is used to invert for the wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. The approach is evaluated on numerically simulated and on measured data. The method is intended for rapid, semi-quantitative screening of pipes

  13. Recent developments in guided wave travel time tomography

    Energy Technology Data Exchange (ETDEWEB)

    Zon, Tim van; Volker, Arno [TNO, Stieltjesweg 1, P.O. box 155 2600 AD Delft (Netherlands)

    2014-02-18

    The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections. Guided wave tomography had been developed to create a map of the wall thickness using the travel times of guided waves. It can be used for both monitoring and for inspection of pipe-segments that are difficult to access, for instance at the location of pipe-supports. An important outcome of the tomography is the minimum remaining wall thickness, as this is critical in the scheduling of a replacement of the pipe-segment. In order to improve the sizing accuracy we have improved the tomography scheme. A number of major improvements have been realized allowing to extend the application envelope to pipes with a larger wall thickness and to larger distances between the transducer rings. Simulation results indicate that the sizing accuracy has improved and that is now possible to have a spacing of 8 meter between the source-ring and the receiver-ring. Additionally a reduction of the number of sensors required might be possible as well.

  14. 1D profiling using highly dispersive guided waves

    International Nuclear Information System (INIS)

    Volker, Arno; Zon, Tim van; Enthoven, Daniel; Verburg, Wesley

    2015-01-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pit-catch configuration at the 12 o'clock position using highly dispersive guided waves. The phase spectrum is used to invert for a wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. An EMAT sensor design has been made to measure at the 12 o'clock position of a pipe. The concept is evaluated on measured data, showing good sizing capabilities on a variety simple defect profiles

  15. 1-D profiling using highly dispersive guided waves

    Science.gov (United States)

    Volker, Arno; van Zon, Tim

    2014-02-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently, inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness of steel pipes. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pitch-catch configuration at the 12 o'clock position using highly dispersive guided waves. After dispersion correction the data collapses to a short pulse, any residual dispersion indicates wall loss. The phase spectrum is used to invert for the wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. The approach is evaluated on numerically simulated and on measured data. The method is intended for rapid, semi-quantitative screening of pipes.

  16. Recent Development in Ultrasonic Guided Waves for Aircraft and Composite Materials

    International Nuclear Information System (INIS)

    Rose, Joseph L.

    2009-01-01

    Emphasis in the paper is placed on describing guided wave successes and challenges for applications in aircraft and composite materials inspection. Guided wave imaging methods discussed includes line of sight, tomography, guided wave C-scan, phased array, and ultrasonic vibration methods. Applications outlined encircles lap splice, bonded repair patch, fuselage corrosion, water loaded structures, delamination, and ice detection and de-icing of various structures.

  17. Guided Acoustic and Optical Waves in Silicon-on-Insulator for Brillouin Scattering and Optomechanics

    Science.gov (United States)

    2016-08-01

    APL PHOTONICS 1, 071301 (2016) Guided acoustic and optical waves in silicon-on- insulator for Brillouin scattering and optomechanics Christopher J...is possible to simultaneously guide optical and acoustic waves in the technologically important silicon on insulator (SOI) material system. Thin...high sound velocity — makes guiding acoustic waves difficult, motivating the use of soft chalcogenide glasses and partial or complete releases (removal

  18. Experiments of Long-range Inspection Method in Straight Pipes using Ultrasonic Guided Waves

    International Nuclear Information System (INIS)

    Eom, H. S.; Lim, S. H.; Kim, J. H.; Joo, Y.S.

    2006-02-01

    This report describes experimental results of a long-range inspection method of pipes using ultrasonic guided waves. In chapter 2, theory of guided wave was reviewed. In chapter 3, equipment and procedures which were used in the experiments were described. Detailed specifications of the specimens described in chapter 4. In chapter 5, we analyzed characteristics of guided wave signals according to shapes and sizes of defects and presents results of various signal processing methods

  19. Ultrasonic guided wave tomography for wall thickness mapping in pipes

    Science.gov (United States)

    Willey, Carson L.

    Corrosion and erosion damage pose fundamental challenges to operation of oil and gas infrastructure. In order to manage the life of critical assets, plant operators must implement inspection programs aimed at assessing the severity of wall thickness loss (WTL) in pipelines, vessels, and other structures. Maximum defect depth determines the residual life of these structures and therefore represents one of the key parameters for robust damage mitigation strategies. In this context, continuous monitoring with permanently installed sensors has attracted significant interest and currently is the subject of extensive research worldwide. Among the different monitoring approaches being considered, significant promise is offered by the combination of guided ultrasonic wave technology with the principles of model based inversion under the paradigm of what is now referred to as guided wave tomography (GWT). Guided waves are attractive because they propagate inside the wall of a structure over a large distance. This can yield significant advantages over conventional pulse-echo thickness gage sensors that provide insufficient area coverage -- typically limited to the sensor footprint. While significant progress has been made in the application of GWT to plate-like structures, extension of these methods to pipes poses a number of fundamental challenges that have prevented the development of sensitive GWT methods. This thesis focuses on these challenges to address the complex guided wave propagation in pipes and to account for parametric uncertainties that are known to affect model based inversion and which are unavoidable in real field applications. The main contribution of this work is the first demonstration of a sensitive GWT method for accurately mapping the depth of defects in pipes. This is achieved by introducing a novel forward model that can extract information related to damage from the complex waveforms measured by pairs of guided wave transducers mounted on the pipe

  20. Borehole guided waves in a non-Newtonian (Maxwell) fluid-saturated porous medium

    International Nuclear Information System (INIS)

    Zhi-Wen, Cui; Jin-Xia, Liu; Ke-Xie, Wang; Gui-Jin, Yao

    2010-01-01

    The property of acoustic guided waves generated in a fluid-filled borehole surrounded by a non-Newtonian (Maxwell) fluid-saturated porous formation with a permeable wall is investigated. The influence of non-Newtonian effects on acoustic guided waves such as Stoneley waves, pseudo-Rayleigh waves, flexural waves, and screw waves propagations in a fluid-filled borehole is demonstrated based on the generalized Biot–Tsiklauri model by calculating their velocity dispersion and attenuation coefficients. The corresponding acoustic waveforms illustrate their properties in time domain. The results are also compared with those based on generalized Biot's theory. The results show that the influence of non-Newtonian effect on acoustic guided wave, especially on the attenuation coefficient of guided wave propagation in borehole is noticeable. (classical areas of phenomenology)

  1. Guided wave tomography in anisotropic media using recursive extrapolation operators

    Science.gov (United States)

    Volker, Arno

    2018-04-01

    Guided wave tomography is an advanced technology for quantitative wall thickness mapping to image wall loss due to corrosion or erosion. An inversion approach is used to match the measured phase (time) at a specific frequency to a model. The accuracy of the model determines the sizing accuracy. Particularly for seam welded pipes there is a measurable amount of anisotropy. Moreover, for small defects a ray-tracing based modelling approach is no longer accurate. Both issues are solved by applying a recursive wave field extrapolation operator assuming vertical transverse anisotropy. The inversion scheme is extended by not only estimating the wall loss profile but also the anisotropy, local material changes and transducer ring alignment errors. This makes the approach more robust. The approach will be demonstrated experimentally on different defect sizes, and a comparison will be made between this new approach and an isotropic ray-tracing approach. An example is given in Fig. 1 for a 75 mm wide, 5 mm deep defect. The wave field extrapolation based tomography clearly provides superior results.

  2. Numerical studies of nonlinear ultrasonic guided waves in uniform waveguides with arbitrary cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Peng; Fan, Zheng, E-mail: ZFAN@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Zhou, Yu [Advanced Remanufacturing and Technology Center (ARTC), 3 Clean Tech Loop, CleanTech Two, Singapore 637143 (Singapore)

    2016-07-15

    Nonlinear guided waves have been investigated widely in simple geometries, such as plates, pipe and shells, where analytical solutions have been developed. This paper extends the application of nonlinear guided waves to waveguides with arbitrary cross sections. The criteria for the existence of nonlinear guided waves were summarized based on the finite deformation theory and nonlinear material properties. Numerical models were developed for the analysis of nonlinear guided waves in complex geometries, including nonlinear Semi-Analytical Finite Element (SAFE) method to identify internal resonant modes in complex waveguides, and Finite Element (FE) models to simulate the nonlinear wave propagation at resonant frequencies. Two examples, an aluminum plate and a steel rectangular bar, were studied using the proposed numerical model, demonstrating the existence of nonlinear guided waves in such structures and the energy transfer from primary to secondary modes.

  3. Metal-dielectric metamaterials for guided wave silicon photonics.

    Science.gov (United States)

    Lupu, A; Dubrovina, N; Ghasemi, R; Degiron, A; de Lustrac, A

    2011-11-21

    The aim of the present paper is to investigate the potential of metallic metamaterials for building optical functions in guided wave optics at 1.5 µm. A significant part of this work is focused on the optimization of the refractive index variation associated with localized plasmon resonances. The minimization of metal related losses is specifically addressed as well as the engineering of the resonance frequency of the localized plasmons. Our numerical modeling results show that a periodic chain of gold cut wires placed on the top of a 100 nm silicon waveguide makes it possible to achieve a significant index variation in the vicinity of the metamaterial resonance and serve as building blocks for implementing optical functions. The considered solutions are compatible with current nano-fabrication technologies. © 2011 Optical Society of America

  4. Simultaneous excitation system for efficient guided wave structural health monitoring

    Science.gov (United States)

    Hua, Jiadong; Michaels, Jennifer E.; Chen, Xin; Lin, Jing

    2017-10-01

    Many structural health monitoring systems utilize guided wave transducer arrays for defect detection and localization. Signals are usually acquired using the ;pitch-catch; method whereby each transducer is excited in turn and the response is received by the remaining transducers. When extensive signal averaging is performed, the data acquisition process can be quite time-consuming, especially for metallic components that require a low repetition rate to allow signals to die out. Such a long data acquisition time is particularly problematic if environmental and operational conditions are changing while data are being acquired. To reduce the total data acquisition time, proposed here is a methodology whereby multiple transmitters are simultaneously triggered, and each transmitter is driven with a unique excitation. The simultaneously transmitted waves are captured by one or more receivers, and their responses are processed by dispersion-compensated filtering to extract the response from each individual transmitter. The excitation sequences are constructed by concatenating a series of chirps whose start and stop frequencies are randomly selected from a specified range. The process is optimized using a Monte-Carlo approach to select sequences with impulse-like autocorrelations and relatively flat cross-correlations. The efficacy of the proposed methodology is evaluated by several metrics and is experimentally demonstrated with sparse array imaging of simulated damage.

  5. 1D profiling using highly dispersive guided waves

    Science.gov (United States)

    Volker, Arno; Brandenburg, Martijn

    2017-02-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Last year an approach was presented using a phase inversion of guided waves that propagated around the circumference of a pipe. This approach works well for larger corrosion spots, but shows significant under-sizing of small spots due to lack of sufficient phase rotation. In this paper the use of arrival time and amplitude loss of higher order circumferential passes is evaluated. Using higher order passes increases sensitivity for sizing smaller defects. Different defect profiles are assumed and the change in arrival time and amplitude loss are calculated using a wave equation based approach for different defect widths and depths. This produces a differential travel time and amplitude change map as function of defect depth and defect width. The actually measured travel time change and amplitude change produces two contours in these maps. Calculating the intersection point gives the defect dimensions. The contours for amplitude loss and travel time change are quite orthogonal, this yields a good discrimination between deep and shallow defects. The approach is evaluated using experimental data from different pipes contain artificial and real defects.

  6. Guided wave propagation as a measure of axial loads in rails

    CSIR Research Space (South Africa)

    Loveday, PW

    2010-03-01

    Full Text Available Guided wave propagation has been proposed as a means to monitor the axial loads in continuously welded railway rails although no practical system has been developed. In this paper, the influence of axial load on the guided wave propagation...

  7. Preliminary design of high-power wave-guide/transmission system

    Indian Academy of Sciences (India)

    ... CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window.

  8. Influence of the Spatial Dimensions of Ultrasonic Transducers on the Frequency Spectrum of Guided Waves.

    Science.gov (United States)

    Samaitis, Vykintas; Mažeika, Liudas

    2017-08-08

    Ultrasonic guided wave (UGW)-based condition monitoring has shown great promise in detecting, localizing, and characterizing damage in complex systems. However, the application of guided waves for damage detection is challenging due to the existence of multiple modes and dispersion. This results in distorted wave packets with limited resolution and the interference of multiple reflected modes. To develop reliable inspection systems, either the transducers have to be optimized to generate a desired single mode of guided waves with known dispersive properties, or the frequency responses of all modes present in the structure must be known to predict wave interaction. Currently, there is a lack of methods to predict the response spectrum of guided wave modes, especially in cases when multiple modes are being excited simultaneously. Such methods are of vital importance for further understanding wave propagation within the structures as well as wave-damage interaction. In this study, a novel method to predict the response spectrum of guided wave modes was proposed based on Fourier analysis of the particle velocity distribution on the excitation area. The method proposed in this study estimates an excitability function based on the spatial dimensions of the transducer, type of vibration, and dispersive properties of the medium. As a result, the response amplitude as a function of frequency for each guided wave mode present in the structure can be separately obtained. The method was validated with numerical simulations on the aluminum and glass fiber composite samples. The key findings showed that it can be applied to estimate the response spectrum of a guided wave mode on any type of material (either isotropic structures, or multi layered anisotropic composites) and under any type of excitation if the phase velocity dispersion curve and the particle velocity distribution of the wave source was known initially. Thus, the proposed method may be a beneficial tool to explain

  9. Interface-guided mode of Lamb waves in a two-dimensional phononic crystal plate

    International Nuclear Information System (INIS)

    Huang Ping-Ping; Yao Yuan-Wei; Zhang Xin; Li Jing; Hu Ai-Zhen; Wu Fu-Gen

    2015-01-01

    We investigate the interface-guided mode of Lamb waves in a phononic crystal heterostructures plate, which is composed of two different semi-infinite phononic crystal (PC) plates. The interface-guided modes of the Lamb wave can be obtained by the lateral lattice slipping or by the interface longitudinal gliding. Significantly, it is observed that the condition to generate the interface-guided modes of the Lamb wave is more demanding than that of the studied fluid–fluid system. The interface-guided modes are strongly affected not only by the relative movement of the two semi-infinite PCs but also by the thickness of the PC plate. (paper)

  10. A Study on the Guided Wave Mode Conversion using Self-calibrating Technique

    International Nuclear Information System (INIS)

    Park, Jung Chul; Cho, Youn Ho

    2000-01-01

    The guided wave mode conversion phenomena were investigated for the NDE of a plate-like structure with thickness variation. The ratios of reflection and transmission (R/T) were measured via the self-calibrating procedure which allows us to obtain experimental guided wave data in a more reliable way regardless of the coupling uncertainty between transducer and specimen. The results on R/T could be used to determine the thickness reduction of the structure. It was shown that not only the incident modes but also the converted ones need to be considered in the self-calibrating guided wave inspection to extract a reasonable correlation between experimental data and the thickness variation. Through this study, the potential of guided wave inspection as a quantitative NDE technique was explored based on the combined concept of self-calibration and multi-mode conversion in guided wave scattering problems

  11. Dynamic Mode Tuning of Ultrasonic Guided Wave Using an Array Transducer

    International Nuclear Information System (INIS)

    Kim, Young H.; Song, Sung J.; Park, Joon S.; Kim, Jae H.; Eom, Heung S.

    2005-01-01

    Ultrasonic guided waves have been widely employed for long range inspection of structures such as plates, rods and pipes. There are numerous modes with different wave velocities, and the appropriate mode selection is one of key techniques in the application of guided waves. In the present work, phase tuning by an array transducer was applied to generate ultrasonic guided waves. For this purpose, 8-channel ultrasonic pulser/receiver and their controller which enables sequential activation of each channels with given time delay were developed. Eight transducers were fabricated in order to generate guided waves by using an array transducer. The selective tuning of wave mode can be achieved by changing the interval between elements of an array transducer

  12. Guided Waves in Structures for SHM The Time - domain Spectral Element Method

    CERN Document Server

    Ostachowicz, Wieslaw; Krawczuk, Marek; Zak, Arkadiusz

    2011-01-01

    Presents the state of the art in the modelling, analysis and experimental investigation of elastic wave propagation using a technique of rapidly increasing interest and development Addressing an important issue in the field of guided-wave-based damage identification and structural health monitoring,Guided Waves in Structures for SHM presents the modelling, analysis and experimental investigation of elastic wave propagation in engineering structures made of isotropic or composite materials. The authors begin by summarising present-day knowledge on elastic wave propagation in solids, focusing on

  13. Third harmonic generation of shear horizontal guided waves propagation in plate-like structures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei Bin [School of Aerospace Engineering, Xiamen University, Xiamen (China); Xu, Chun Guang [School of Mechanical Engineering, Beijing Institute of Technology, Beijing (China); Cho, Youn Ho [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

    2016-04-15

    The use of nonlinear ultrasonics wave has been accepted as a promising tool for monitoring material states related to microstructural changes, as it has improved sensitivity compared to conventional non-destructive testing approaches. In this paper, third harmonic generation of shear horizontal guided waves propagating in an isotropic plate is investigated using the perturbation method and modal analysis approach. An experimental procedure is proposed to detect the third harmonics of shear horizontal guided waves by electromagnetic transducers. The strongly nonlinear response of shear horizontal guided waves is measured. The accumulative growth of relative acoustic nonlinear response with an increase of propagation distance is detected in this investigation. The experimental results agree with the theoretical prediction, and thus providing another indication of the feasibility of using higher harmonic generation of electromagnetic shear horizontal guided waves for material characterization.

  14. Guided wave and damage detection in composite laminates using different fiber optic sensors.

    Science.gov (United States)

    Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

    2009-01-01

    Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

  15. Traveling wave model for laser-guided discharges

    International Nuclear Information System (INIS)

    Lampe, Martin; Fernsler, Richard F.; Slinker, Steven P.; Gordon, Daniel F.

    2010-01-01

    We present an easily solvable 1D traveling wave model for laser-guided discharges. By assuming constant propagation speed u, the hydro/electrodynamic/chemistry equations are reduced to ordinary differential equations in retarded time τ. Negative discharges are shown to propagate only if u>μE b , where μ is electron mobility and E b is the breakdown field; positive discharges propagate only if the channel preconductance exceeds ∼6x10 -11 m/Ω. The axial electric field E is shown to spike up to several times E b and then relax to ∼E b for as long as the gas remains cold. In this streamer region, the channel conductance, current, and potential all increase linearly with τ. The transition to the leader stage, where E is much smaller, occurs in two steps: excitation of vibrational and low-lying electronic states, then gas heating. The propagation range decreases as a function of initial radius and (for given maximum voltage) of the voltage rise rate. Expansion of the hot channel is shown to increase the range.

  16. Large scale implementation of guided wave based broken rail monitoring

    Science.gov (United States)

    Burger, Francois A.; Loveday, Philip W.; Long, Craig S.

    2015-03-01

    A guided wave ultrasound system has been developed over the past 17 years to detect breaks in continuously welded rail track. Installation of the version 4 system on an 840 km long heavy duty freight line was conducted between January 2013 and June 2014. The system operates in pitch - catch mode with alternate transmit and receive transducers spaced approximately 1km apart. If the acoustic signal is not received at the receive station an alarm is triggered to indicate a break in the rail between the transmit station and the receive station. The system is permanently installed, powered by solar panels and issues broken rail alarms using the GSM network where available, and digital radio technology in other areas. A total of 931 stations were installed and the entire length of rail is interrogated every fifteen minutes. The system operates reliably although some problems involving unreliable GSM communication and theft of solar panels have been experienced. In the first two months of operation four broken rails were detected and train operation was halted temporarily for repairs.

  17. Experimental Results of Guided Wave Travel Time Tomography

    Science.gov (United States)

    Volker, Arno; Mast, Arjan; Bloom, Joost

    2010-02-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Both economical and social requirements are pushing the industry to even higher levels of availability, reliability and safety of installations. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections reducing uncertainty and extending inspection intervals. Guided wave travel time tomography is a promising method to monitor the wall thickness quantitatively over large areas. Obviously the robustness and reliability of such a monitoring system is of paramount importance. Laboratory experiments have been carried out on a 10″ pipe with a nominal wall thickness of 8 mm. Multiple, inline defects have been created with a realistic morphology. The depth of the defects was increased stepwise from 0.5 mm to 2 mm. Additionally the influences of the presence of liquid inside the pipe and surface roughness have been evaluated as well. Experimental results show that this method is capable of providing quantitative wall thickness information over a distance of 4 meter, with a sufficient accuracy such that results can be used for trending. The method has no problems imaging multiple defects.

  18. Assessment of Pipe Wall Loss Using Guided Wave Testing

    International Nuclear Information System (INIS)

    Joo, Kyung Mun; Jin, Seuk Hong; Moon, Yong Sig

    2010-01-01

    Flow accelerated corrosion(FAC) of carbon steel pipes in nuclear power plants has been known as one of the major degradation mechanisms. It could have bad influence on the plant reliability and safety. Also detection of FAC is a significant cost to the nuclear power plant because of the need to remove and replace insulation. Recently, the interest of the guided wave testing(GWT) has grown because it allows long range inspection without removing insulation of the pipe except at the probe position. If GWT can be applied to detection of FAC damages, it will can significantly reduce the cost for the inspection of the pipes. The objective of this study was to determine the capability of GWT to identify location of FAC damages. In this paper, three kinds of techniques were used to measure the amplitude ratio between the first and the second welds at the elbow area of mock-ups that contain real FAC damages. As a result, optimal inspection technique and minimum detectability to detect FAC damages drew a conclusion

  19. Ultrasonic Guided Waves in Piezoelectric Layered Composite with Different Interfacial Properties

    Directory of Open Access Journals (Sweden)

    Xiao Chen

    2011-01-01

    Full Text Available Combining the propagation model of guided waves in a multilayered piezoelectric composite with the interfacial model of rigid, slip, and weak interfaces, the generalized dispersion characteristic equations of guided waves propagating in a piezoelectric layered composite with different interfacial properties are derived. The effects of the slip, weak, and delamination interfaces in different depths on the dispersion properties of the lowest-order mode ultrasonic guided wave are analyzed. The theory would be used to characterize the interfacial properties of piezoelectric layered composite nondestructively.

  20. A Study on Elastic Guided Wave Modal Characteristics in Multi-Layered Structures

    International Nuclear Information System (INIS)

    Cho, Youn Ho; Lee, Chong Myoung

    2008-01-01

    In this study, we have developed a program which can calculate phase and group velocities, attenuation and wave structures of each mode in multi-layered plates. The wave structures of each mode are obtained, varying material properties and number of layers. The key in the success of guided wave NDE is how to optimize the mode selection scheme by minimizing energy loss when a structure is in contact with liquid. In this study, the normalized out-of-plane displacements at the surface of a free plate are used to predict the variation of modal attenuation and verily the correlation between attenuation and wave structure. It turns out that the guided wave attenuation can be efficiently obtain from the out-of-plane displacement variation of a free wave guide alleviating such mathematical difficulties in extracting complex roots for the eigenvalue problem of a liquid loaded wave guide. Through this study, the concert to optimize guided wave mode selection is accomplished to enhance sensitivity and efficiency in nondestructive evaluation for multi-layered structures.

  1. Guided Seismic Waves: Possible Diagnostics for Hot Plumes in the Mantle

    Science.gov (United States)

    Evans, J. R.; Julian, B. R.; Foulger, G. R.

    2005-12-01

    Seismic waves potentially provide by far the highest resolution view of the three-dimensional structure of the mantle, and the hope of detecting wave-speed anomalies caused by hot or compositionally buoyant mantle plumes has been a major incentive to the development of tomographic seismic techniques. Seismic tomography is limited, however, by the uneven geographical distribution of earthquakes and seismometers, which can produce artificial tomographic wave-speed anomalies that are difficult to distinguish from real structures in the mantle. An alternate approach may be possible, because hot plumes and possibly some compositional upwellings would have low seismic-wave speeds and would act as efficient waveguides over great depth ranges in the mantle. Plume-guided waves would be little affected by bends or other geometric complexities in the waveguides (analogously to French horns and fiber-optic cables), and their dispersion would make them distinctive on seismograms and would provide information on the size and structure of the waveguide. The main unanswered question is whether guided waves in plumes could be excited sufficiently to be observable. Earthquakes do not occur in the deep mantle, but at least two other possible sources of excitation can be imagined: (1) shallow earthquakes at or near plume-fed hotspots; and (2) coupling of plume-guided waves to seismic body waves near the bottom of the mantle. In the first case, downward-traveling guided waves transformed to seismic body waves at the bottom of the waveguide would have to be detected at teleseismic distances. In the second case, upward-traveling guided waves generated by teleseismic body waves would be detected on seismometers at hotspots. Qualitative reasoning based on considerations of reciprocity suggests that the signals in these two situations should be similar in size and appearance. The focusing of seismic core phases at caustics would amplify plume waves excited by either mechanism (1) or (2) at

  2. Properties of Love waves in a piezoelectric layered structure with a viscoelastic guiding layer

    International Nuclear Information System (INIS)

    Liu, Jiansheng; Wang, Lijun; Lu, Yanyan; He, Shitang

    2013-01-01

    A theoretical method is developed for analyzing Love waves in a structure with a viscoelastic guiding layer bounded on a piezoelectric substrate. The dispersion equation previously derived for piezoelectric Love waves propagating in the layered structure with an elastic layer is adopted for analyzing a structure with a viscoelastic layer. A Maxwell–Weichert model is introduced to describe the shear stiffness of a polymeric material. Newton’s method is employed for the numerical calculation. The dispersion equation for piezoelectric–elastic Love waves is proved suitable for solving a structure with a viscoelastic layer on a piezoelectric substrate. The theoretical results indicate that the propagation velocity of the Love wave is mainly decided by the shear stiffness of the guiding layer, whereas the propagation loss is approximately proportional to its viscosity. A detailed experimental study was conducted on a Love wave delay line fabricated on an ST-90° X quartz substrate and overlaid with various thicknesses of SU-8 guiding layers. A tail-raising caused by the viscosity of the guiding layer existed in both the calculated and the measured propagation velocities. The calculated insertion loss of the Love wave delay lines was in good agreement with the measured results. The method and the results presented in this paper are beneficial to the design of Love wave sensors with a viscoelastic guiding layer. (paper)

  3. Experimental and numerical study of guided wave propagation in a thin metamaterial plate

    International Nuclear Information System (INIS)

    Zhu, R.; Huang, G.L.; Huang, H.H.; Sun, C.T.

    2011-01-01

    In this Letter, both in-plane and out-of-plane guided waves in a thin plate with local resonators are studied numerically and experimentally. Through the numerical simulation, a new metamaterial plate design is achieved for a low-frequency bandgap in both in-plane and out-of-plane guided waves. Experiments were conducted to validate the numerical design. In the experiment, piezoelectric transducers were used to generate and receive guided wave signals. The results show that the numerical predictions are in very good agreement with the experimental measurements. Specifically, the connection between the local resonance in the thin plate and its wave attenuation mechanism was discussed. -- Highlights: → Both in-plane and out-of-plane guided waves in a thin plate with local resonators are studied numerically and experimentally. → A new metamaterial plate design is achieved for a low-frequency bandgap in both in-plane and out-of-plane guided waves. → Experiments were conducted to validate the numerical design. → The connection between the local resonance in the thin plate and its wave attenuation mechanism was investigated.

  4. Effect of pressurization on helical guided wave energy velocity in fluid-filled pipes.

    Science.gov (United States)

    Dubuc, Brennan; Ebrahimkhanlou, Arvin; Salamone, Salvatore

    2017-03-01

    The effect of pressurization stresses on helical guided waves in a thin-walled fluid-filled pipe is studied by modeling leaky Lamb waves in a stressed plate bordered by fluid. Fluid pressurization produces hoop and longitudinal stresses in a thin-walled pipe, which corresponds to biaxial in-plane stress in a plate waveguide model. The effect of stress on guided wave propagation is accounted for through nonlinear elasticity and finite deformation theory. Emphasis is placed on the stress dependence of the energy velocity of the guided wave modes. For this purpose, an expression for the energy velocity of leaky Lamb waves in a stressed plate is derived. Theoretical results are presented for the mode, frequency, and directional dependent variations in energy velocity with respect to stress. An experimental setup is designed for measuring variations in helical wave energy velocity in a thin-walled water-filled steel pipe at different levels of pressure. Good agreement is achieved between the experimental variations in energy velocity for the helical guided waves and the theoretical leaky Lamb wave solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Stress wave timing nondestructive evaluation tools for inspecting historic structures : a guide for use and interpretation.

    Science.gov (United States)

    Robert Ross; Roy F. Pellerin; Norbert Volny; William W. Salsig; Robert H. Falk

    2000-01-01

    This guide was prepared to assist inspectors in the use of stress wave timing instruments and various methods of locating and defining areas of decay in timber members in historic structures. The first two sections provide (a) background information regarding conventional methods to locate and measure decay in historic structures and (b) the principles of stress wave...

  6. Modal approach for the full simulation of nondestructive tests by elastic guided waves

    International Nuclear Information System (INIS)

    Jezzine, K.

    2006-11-01

    Tools for simulating nondestructive tests by elastic guided waves are developed. Two overall formulations based on modal formalism and reciprocity are derived depending on whether transmission and reception are separated or not. They relate phenomena of guided wave radiation by a transducer, their propagation, their scattering by a non-uniformity of the guide or a defect and their reception. Receiver electrical output is expressed as a product of terms relating to each phenomenon that can be computed separately. Their computation uses developments based on the semi-analytical finite elements method, dealing with guides of arbitrary cross-section and cracks normal to the guide axis. Simulation tools are used to study means for selecting a single mode using a transducer positioned on the guide section, such a selection making easier the interpretation of the results of testing by guided waves. Two methods of mode selection are proposed, based on the use of two specific frequencies (which existence depends on guide geometry and mode symmetry). Mimicking the normal stress distribution of the mode at one of these two frequencies or the other makes it possible to radiate solely or predominantly the mode chosen. Examinations are simulated in configurations using a single or two separated transducers positioned on the section of various guide geometries and cracks of various shapes. The interest and performances of the two methods of mode selection are studied in these configurations. (author)

  7. Theoretical study of the attenuation of a gaussian beam penetrating into a dielectric circular wave guide

    International Nuclear Information System (INIS)

    Crenn, J.P.

    1981-07-01

    It is proposed to draw up an approximate formula directly giving the attenuation of a gaussian beam penetrating into a superdimensioned dielectric circular wave guide. This formula is derived from optical laws, i.e. Fresnel's formulae of the reflexion of a wave on a dielectric to which a correcting term due to diffraction has been added. The results given by this formula are compared with the existing results, based on the breakdown of a gaussian beam into propagation modes, thereby enabling their validity and the field of use to be checked. An application is then made to the wave guides that will be employed in the infrared interferometer fitted in JET [fr

  8. Quantification of thickness loss in a liquid-loaded plate using ultrasonic guided wave tomography

    Science.gov (United States)

    Rao, Jing; Ratassepp, Madis; Fan, Zheng

    2017-12-01

    Ultrasonic guided wave tomography (GWT) provides an attractive solution to map thickness changes from remote locations. It is based on the velocity-to-thickness mapping employing the dispersive characteristics of selected guided modes. This study extends the application of GWT on a liquid-loaded plate. It is a more challenging case than the application on a free plate, due to energy of the guided waves leaking into the liquid. In order to ensure the accuracy of thickness reconstruction, advanced forward models are developed to consider attenuation effects using complex velocities. The reconstruction of the thickness map is based on the frequency-domain full waveform inversion (FWI) method, and its accuracy is discussed using different frequencies and defect dimensions. Validation experiments are carried out on a water-loaded plate with an irregularly shaped defect using S0 guided waves, showing excellent performance of the reconstruction algorithm.

  9. Guided-wave tomographic imaging of plate defects by laser-based ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Park, Junpil; Lim, Ju Young; Cho, Youn Ho [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

    2016-12-15

    Contact-guided-wave tests are impractical for investigating specimens with limited accessibility and rough surfaces or complex geometric features. A non-contact setup with a laser-ultrasonic transmitter and receiver is quite attractive for guided-wave inspection. In the present work, we developed a non-contact guided-wave tomography technique using the laser-ultrasonic technique in a plate. A method for Lamb-wave generation and detection in an aluminum plate with a pulsed laser-ultrasonic transmitter and Michelson-interferometer receiver was developed. The defect shape and area in the images obtained using laser scanning, showed good agreement with the actual defect. The proposed approach can be used as a non-contact online inspection and monitoring technique.

  10. A study on laser-based ultrasonic technique by the use of guided wave tomographic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Park, Junpil, E-mail: jpp@pusan.ac.kr; Lim, Juyoung, E-mail: jpp@pusan.ac.kr [Graduate school, School of Mechanical Engineering, Pusan National University (Korea, Republic of); Cho, Younho [School of Mechanical Engineering, Pusan National University (Korea, Republic of); Krishnaswamy, Sridhar [Center for Quality Engineering and Failure Prevention, Northwestern University, Evanston, IL (United States)

    2015-03-31

    Guided wave tests are impractical for investigating specimens with limited accessibility and coarse surfaces or geometrically complicated features. A non-contact setup with a laser ultrasonic transmitter and receiver is the classic attractive for guided wave inspection. The present work was done to develop a non-contact guided-wave tomography technique by laser ultrasonic technique in a plate-like structure. A method for Lam wave generation and detection in an aluminum plate with a pulse laser ultrasonic transmitter and a Michelson interferometer receiver has been developed. In the images obtained by laser scanning, the defect shape and area showed good agreement with the actual defect. The proposed approach can be used as a non-contact-based online inspection and monitoring technique.

  11. Guided-wave tomography imaging plate defects by laser-based ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jun Pil; Lim, Ju Young; Cho, Youn Ho [School of Mechanical Engineering, Pusan National University, Pusan (Korea, Republic of)

    2014-12-15

    Contact-guided-wave tests are impractical for investigating specimens with limited accessibility and rough surfaces or complex geometric features. A non-contact setup with a laser-ultrasonic transmitter and receiver is quite attractive for guided-wave inspection. In the present work, we developed a non-contact guided-wave tomography technique using the laser-ultrasonic technique in a plate. A method for Lamb-wave generation and detection in an aluminum plate with a pulsed laser-ultrasonic transmitter and Michelson-interferometer receiver was developed. The defect shape and area in the images obtained using laser scanning, showed good agreement with the actual defect. The proposed approach can be used as a non-contact online inspection and monitoring technique.

  12. Noncontact measurement of guided ultrasonic wave scattering for fatigue crack characterization

    Science.gov (United States)

    Fromme, P.

    2013-04-01

    Fatigue cracks can develop in aerospace structures at locations of stress concentration such as fasteners. For the safe operation of the aircraft fatigue cracks need to be detected before reaching a critical length. Guided ultrasonic waves offer an efficient method for the detection and characterization of fatigue cracks in large aerospace structures. Noncontact excitation of guided waves was achieved using electromagnetic acoustic transducers (EMAT). The transducers were developed for the specific excitation of the A0 Lamb mode. Based on the induced eddy currents in the plate a simple theoretical model was developed and reasonably good agreement with the measurements was achieved. However, the detection sensitivity for fatigue cracks depends on the location and orientation of the crack relative to the measurement locations. Crack-like defects have a directionality pattern of the scattered field depending on the angle of the incident wave relative to the defect orientation and on the ratio of the characteristic defect size to wavelength. The detailed angular dependency of the guided wave field scattered at crack-like defects in plate structures has been measured using a noncontact laser interferometer. Good agreement with 3D Finite Element simulation predictions was achieved for machined part-through and through-thickness notches. The amplitude of the scattered wave was quantified for a variation of angle of the incident wave relative to the defect orientation and the defect depth. These results provide the basis for the defect characterization in aerospace structures using guided wave sensors.

  13. Guided Wave Propagation Study on Laminated Composites by Frequency-Wavenumber Technique

    Science.gov (United States)

    Tian, Zhenhua; Yu, Lingyu; Leckey, Cara A. C.

    2014-01-01

    Toward the goal of delamination detection and quantification in laminated composites, this paper examines guided wave propagation and wave interaction with delamination damage in laminated carbon fiber reinforced polymer (CFRP) composites using frequency-wavenumber (f-kappa) analysis. Three-dimensional elastodynamic finite integration technique (EFIT) is used to acquire simulated time-space wavefields for a CFRP composite. The time-space wavefields show trapped waves in the delamination region. To unveil the wave propagation physics, the time-space wavefields are further analyzed by using two-dimensional (2D) Fourier transforms (FT). In the analysis results, new f-k components are observed when the incident guided waves interact with the delamination damage. These new f-kappa components in the simulations are experimentally verified through data obtained from scanning laser Doppler vibrometer (SLDV) tests. By filtering the new f-kappa components, delamination damage is detected and quantified.

  14. Propagation of ultrasonic guided waves in an acrylic plate as a cortical-bone-mimicking phantom

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Il [Kangwon National University, Chuncheon (Korea, Republic of); Choi, Bok Kyoung [Maritime Security Research Center, KIOST, Ansan (Korea, Republic of)

    2014-12-15

    The present study aims to investigate the propagation of ultrasonic guided waves in an acrylic plate as a cortical-bone-mimicking phantom. The velocities of the guided waves in a 5-mm-thick acrylic plate were measured by using the axial transmission technique. A pure A0 Lamb mode could be successfully launched in the 5-mm-thick acrylic plate through a time reversal process of Lamb waves, consistent with the fact that the time reversal process can automatically compensate for the dispersive nature of Lamb waves. The experimental velocities of the slow guided wave (SGW) and the time-reversed Lamb wave were found to be in reasonable agreement with the theoretical group velocity of the A0 Lamb mode, suggesting that both the SGW and the time-reversed Lamb wave excited in the 5-mm-thick acrylic plate correspond to the A0 Lamb mode. These results suggest that the time reversal process of Lamb waves can be usefully applied to noninvasive characterization of long cortical bones.

  15. Propagation of ultrasonic guided waves in an acrylic plate as a cortical-bone-mimicking phantom

    International Nuclear Information System (INIS)

    Lee, Kang Il; Choi, Bok Kyoung

    2014-01-01

    The present study aims to investigate the propagation of ultrasonic guided waves in an acrylic plate as a cortical-bone-mimicking phantom. The velocities of the guided waves in a 5-mm-thick acrylic plate were measured by using the axial transmission technique. A pure A0 Lamb mode could be successfully launched in the 5-mm-thick acrylic plate through a time reversal process of Lamb waves, consistent with the fact that the time reversal process can automatically compensate for the dispersive nature of Lamb waves. The experimental velocities of the slow guided wave (SGW) and the time-reversed Lamb wave were found to be in reasonable agreement with the theoretical group velocity of the A0 Lamb mode, suggesting that both the SGW and the time-reversed Lamb wave excited in the 5-mm-thick acrylic plate correspond to the A0 Lamb mode. These results suggest that the time reversal process of Lamb waves can be usefully applied to noninvasive characterization of long cortical bones.

  16. Using the gauge condition to simplify the elastodynamic analysis of guided wave propagation

    Directory of Open Access Journals (Sweden)

    Md Yeasin BHUIYAN

    2016-09-01

    Full Text Available In this article, gauge condition in elastodynamics is explored more to revive its potential capability of simplifying wave propagation problems in elastic medium. The inception of gauge condition in elastodynamics happens from the Navier-Lame equations upon application of Helmholtz theorem. In order to solve the elastic wave problems by potential function approach, the gauge condition provides the necessary conditions for the potential functions. The gauge condition may be considered as the superposition of the separate gauge conditions of Lamb waves and shear horizontal (SH guided waves respectively, and thus, it may be resolved into corresponding gauges of Lamb waves and SH waves. The manipulation and proper choice of the gauge condition does not violate the classical solutions of elastic waves in plates; rather, it simplifies the problems. The gauge condition allows to obtain the analytical solution of complicated problems in a simplified manner.

  17. The study on nondestructive evaluation for a tubular structure by the lamb-type guided wave wedge

    International Nuclear Information System (INIS)

    Cho, Yun Ho; Park, Jung Chul

    1998-01-01

    The study on the cylindrical guided wave was carried out to investigate its feasibility for nondestructive evaluation of tubular structures such as heat exchanger tubings of power industries and various pipings of chemical plants. The concept of wedge design and incident angle selection to optimize guided wave generation is presented based on the dispersion theory and the snell's law for the cylindrical guided wave. The brass tubes with artificial defects in the circumferential or axial direction were used for detect defection experiments. It was found that guided wave sensitivity for detecting an axial defect can be remarkably improved by using non-axisymmetrically launched guided waves. Through this study, it is expected that the guided wave can be successfully applied to tubular structure inspections as an more advanced and efficient NDE technique than a conventional point-by-point technique.

  18. Application of the cylindrically guided wave technique for bolt and pump shaft inspections

    International Nuclear Information System (INIS)

    Light, G.M.; Ruescher, E.H.; Bloom, E.A.; Joshi, N.R.; Tsai, Y.M.; Liu, S.N.

    1993-01-01

    Elastic wave propagation in a bounded medium significantly differs from that in an unbounded medium. The bounded medium in the form of a cylinder acts like a solid waveguide directing the wave with its geometry. A continuous or a pulsed wave interacts with cylindrical boundaries producing mode-converted signals in addition to the backwall echo. The signals are received at constant time intervals directly proportional to the diameter of a solid cylindrical object such as a bolt or an anchor stud. The Cylindrically Guided Wave Technique (CGWT) makes intelligent use of the mode-converted signals, or trailing pulses, to detect corrosion wastages and cracks in cylindrical objects. (orig.)

  19. Study of guided wave transmission through complex junction in sodium cooled reactor

    International Nuclear Information System (INIS)

    Elie, Q.; Le Bourdais, F.; Jezzine, K.; Baronian, V.

    2015-01-01

    Ultrasonic guided wave techniques are seen as suitable candidates for the inspection of welded structures within sodium cooled fast reactors (SFR), as the long range propagation of guided waves without amplitude attenuation can overcome the accessibility problem due to the liquid sodium. In the context of the development of the Advanced Sodium Test Reactor for Industrial Demonstration (ASTRID), the French Atomic Commission (CEA) investigates non-destructive testing techniques based on guided wave propagation. In this work, guided wave NDT methods are applied to control the integrity of welds located in a junction-type structure welded to the main vessel. The method presented in this paper is based on the analysis of scattering matrices peculiar to each expected defect, and takes advantage of the multi-modal and dispersive characteristics of guided wave generation. In a simulation study, an algorithm developed using the CIVA software is presented. It permits selecting appropriate incident modes to optimize detection and identification of expected flawed configurations. In the second part of this paper, experimental results corresponding to a first validation step of the simulation results are presented. The goal of the experiments is to estimate the effectiveness of the incident mode selection in plates. The results show good agreement between experience and simulation. (authors)

  20. On the effects of geometry on guided electromagnetic waves

    Directory of Open Access Journals (Sweden)

    Tucker Robin W.

    2007-01-01

    Full Text Available The method of moving (Cartan coframes is used to analyze the influence of geometry on the behavior of electromagnetic fields in confining guides and the effect of such fields on their ultra-relativistic sources. Such issues are of relevance to a number of topical problems in accelerator science where the need to control the motion of high current-density micro-meter size bunches of relativistic radiating charge remains a technical and theoretical challenge. By dimensionally reducing the exterior equations for the sources and fields on spacetime using symmetries exhibited by the confining guides one achieves a unifying view that offers natural perturbative approaches for dealing with smooth non-uniform and curved guides. The issue of the back-reaction of radiation fields on the sources is approached in terms of a simple charged relativistic fluid model. .

  1. Damage evaluation by a guided wave-hidden Markov model based method

    Science.gov (United States)

    Mei, Hanfei; Yuan, Shenfang; Qiu, Lei; Zhang, Jinjin

    2016-02-01

    Guided wave based structural health monitoring has shown great potential in aerospace applications. However, one of the key challenges of practical engineering applications is the accurate interpretation of the guided wave signals under time-varying environmental and operational conditions. This paper presents a guided wave-hidden Markov model based method to improve the damage evaluation reliability of real aircraft structures under time-varying conditions. In the proposed approach, an HMM based unweighted moving average trend estimation method, which can capture the trend of damage propagation from the posterior probability obtained by HMM modeling is used to achieve a probabilistic evaluation of the structural damage. To validate the developed method, experiments are performed on a hole-edge crack specimen under fatigue loading condition and a real aircraft wing spar under changing structural boundary conditions. Experimental results show the advantage of the proposed method.

  2. Wall thinning inspection technique for large-diameter piping using guided wave

    International Nuclear Information System (INIS)

    Miki, Masahiro; Nagashima, Yoshiaki; Endou, Masao; Kodaira, Kojiro; Maniwa, Kazuhiko

    2009-01-01

    Guided wave inspection technique is effective for detecting defects like corrosion in piping, because it can perform long range inspection. It is possible to expect this inspection as a method that leads to the decrease of the inspection process and its cost, because the incidental work can be reduced. Especially, the contraction effect of the inspection work is extensive in large-diameter piping inspection. In this paper, we introduce the guided wave inspection system to large-diameter piping. The feature is a guided wave sensor that can freely transform according to the curvature of inspection object, and portable inspection equipment. We discuss the result of detection examination for artificial wall-thinning in large-diameter piping using this system. (author)

  3. User guide – COE Calculation Tool for Wave Energy Converters

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez; Kofoed, Jens Peter; Jensen, Niels Ejner Helstrup

    Aalborg University together with Energinet.dk and Julia F. Chozas Consulting Engineer, have released a freely available online spreadsheet to evaluate the Levelised Cost of Energy (LCOE) for wave energy projects. The open-access tool calculates the LCOE based on the power production of a Wave...... Energy Converter (WEC) at a particular location. Production data may derive from laboratory testing, numerical modelling or from sea trials. The tool has been developed as a transparent and simple model that evaluates WEC’s economic feasibility in a range of locations, while scaling WEC’s features...

  4. Spinor-electron wave guided modes in coupled quantum wells structures by solving the Dirac equation

    International Nuclear Information System (INIS)

    Linares, Jesus; Nistal, Maria C.

    2009-01-01

    A quantum analysis based on the Dirac equation of the propagation of spinor-electron waves in coupled quantum wells, or equivalently coupled electron waveguides, is presented. The complete optical wave equations for Spin-Up (SU) and Spin-Down (SD) spinor-electron waves in these electron guides couplers are derived from the Dirac equation. The relativistic amplitudes and dispersion equations of the spinor-electron wave-guided modes in a planar quantum coupler formed by two coupled quantum wells, or equivalently by two coupled slab electron waveguides, are exactly derived. The main outcomes related to the spinor modal structure, such as the breaking of the non-relativistic degenerate spin states, the appearance of phase shifts associated with the spin polarization and so on, are shown.

  5. Mode repulsion of ultrasonic guided waves in rails

    CSIR Research Space (South Africa)

    Loveday, Philip W

    2018-03-01

    Full Text Available . The modes can therefore be numbered in the same way that Lamb waves in plates are numbered, making it easier to communicate results. The derivative of the eigenvectors with respect to wavenumber contains the same repulsion term and shows how the mode shapes...

  6. A Plant's Response to Gravity as a Wave Guide Phenomenon

    Science.gov (United States)

    Wagner, Orvin

    1997-11-01

    Plant experimental data provides a unifying wave theory (W-wave theory) for the growth and development of plants. A plant's response to gravity is an important aspect of this theory. It appears that a plant part is tuned to the angle with which it initially grew with respect to the gravitational field and changes produce correction responses. This is true because the velocity of W-waves (whose standing waves determine plant structure) within plant tissue is found to be different in different directions (angle a) with respect to the gravitational field. I found that there are preferred values of a, namely integral multiples of near 5 degrees for some plants. Conifers apparently are more sensitive to the gravitational field than deciduous trees, in the cases studied, so their structure is determined in more detail by the gravitational field. A plant's response to gravity appears to be a fundamental phenomenon and may provide a new model for gravity that can be experimentally verified in the laboratory. Along these same lines accelerometers placed in plant tissue indicate that plants produce gravity related forces that facilitate sap flow. See the

  7. Damage detection in submerged plates using ultrasonic guided waves

    Indian Academy of Sciences (India)

    eddy currents. Most of the ... istics, Lamb waves were used for damage detection and inspection on a variety of applications like strips and ...... wide and 0.5 mm deep (12.5% of the plate thickness) was machined on the plate (figure 17) and.

  8. CNS role evolution.

    Science.gov (United States)

    Payne, J L; Baumgartner, R G

    1996-01-01

    THE CNS ROLE has been actualized in a variety of ways. Flexibility-inherent in the role-and the revolution in health care consciousness tend to place the CNS at risk for criticism regarding value to the organization. At Vanderbilt University Medical Center, a CNS task force evaluated the current reality of CNS practice and recommended role changes to include the financial analysis of patient care. After incorporating a financial perspective into our present practice, we have embarked on an interesting journey of post-Master's degree study, that of the tertiary care nurse practitioner. This practice option could elevated the clinical and financial aspects of providing cost-effective health care to a more autonomous role form; however, the transition has been challenging. Since 1990, the American Nurses Association has recommended that nursing school curricula change to meet the needs of the health care environment and provide increased career flexibility through creating one advanced degree incorporating both CNS and NP functions. Swiftly moving past differences and toward similarities will bridge the gap for advanced practice nurses in the future.

  9. A New Detecting Technology for External Anticorrosive Coating Defects of Pipelines Based on Ultrasonic Guided Wave

    Science.gov (United States)

    Liu, Shujun; Zuo, Yonggang; Zhang, Zhen

    2018-01-01

    The external anticorrosive coating is the shelter for preventing steel pipelines from Corrosive damage. A number of pipelines face severe corrosive problems for the performance decrease of the coating, especially during long-term services, which usually led to safety accidents. To solve the detection problem about the defect of anticorrosive layer for pipeline, a new detection method for anticorrosive layer of pipelines based on Ultrasonic Guided Wave was proposed in the paper. The results from the investigation show a possibility of using the Ultrasonic Guided Wave method for detecting the damage of pipeline’s External Anticorrosive Coating.

  10. Modeling of microwave applicators with an excitation through the wave guide using TLM method

    Directory of Open Access Journals (Sweden)

    Ranđelović Tijana

    2005-01-01

    Full Text Available In this paper, a real microwave applicator with a wave guide used to launch the energy from the source into the cavity is analyzed using 3D TLM method. In order to investigate the influence of the positions and number of feed wave guides to the number of the resonant modes inside the cavity, obtained results are compared with analytical results and results obtained by using TLM software with an impulse excitation as well. TLM method is applied to the both empty and loaded rectangular metallic cavity, and a very good agreement between simulated and experimental results is achieved.

  11. Experimental Observation of Cumulative Second-Harmonic Generation of Circumferential Guided Wave Propagation in a Circular Tube

    International Nuclear Information System (INIS)

    Deng Ming-Xi; Gao Guang-Jian; Li Ming-Liang

    2015-01-01

    The experimental observation of cumulative second-harmonic generation of the primary circumferential guided wave propagation is reported. A pair of wedge transducers is used to generate the primary circumferential guided wave desired and to detect its fundamental-frequency and second-harmonic amplitudes on the outside surface of the circular tube. The amplitudes of the fundamental waves and the second harmonics of the circumferential guided wave propagation are measured for different separations between the two wedge transducers. At the driving frequency where the primary and the double-frequency circumferential guided waves have the same linear phase velocities, the clear second-harmonic signals can be observed. The quantitative relationships between the second-harmonic amplitudes and circumferential angle are analyzed. It is experimentally verified that the second harmonics of primary circumferential guided waves do have a cumulative growth effect with the circumferential angle. (paper)

  12. Development of a guided wave simulator and its application to monitoring of pipe wall thinning

    International Nuclear Information System (INIS)

    Furukawa, Akinori; Kojima, Fumio

    2009-01-01

    Motivated by growing demand for quantitative nondestructive evaluation of pipe wall thinning, the aim of this paper is to develop a simulator for guided wave analysis. First, an inspection system can be represented by a linear elastic system in cylindrical coordinates. Secondly a dynamical numerical scheme for wave propagation on a pipe wall is proposed based on Fourier-Galerkin approach. Finally, the effectiveness and validity of the proposed method are shown in computational experiments. (author)

  13. Development of a Novel Guided Wave Generation System Using a Giant Magnetostrictive Actuator for Nondestructive Evaluation.

    Science.gov (United States)

    Luo, Mingzhang; Li, Weijie; Wang, Junming; Wang, Ning; Chen, Xuemin; Song, Gangbing

    2018-03-04

    As a common approach to nondestructive testing and evaluation, guided wave-based methods have attracted much attention because of their wide detection range and high detection efficiency. It is highly desirable to develop a portable guided wave testing system with high actuating energy and variable frequency. In this paper, a novel giant magnetostrictive actuator with high actuation power is designed and implemented, based on the giant magnetostrictive (GMS) effect. The novel GMS actuator design involves a conical energy-focusing head that can focus the amplified mechanical energy generated by the GMS actuator. This design enables the generation of stress waves with high energy, and the focusing of the generated stress waves on the test object. The guided wave generation system enables two kinds of output modes: the coded pulse signal and the sweep signal. The functionality and the advantages of the developed system are validated through laboratory testing in the quality assessment of rock bolt-reinforced structures. In addition, the developed GMS actuator and the supporting system are successfully implemented and applied in field tests. The device can also be used in other nondestructive testing and evaluation applications that require high-power stress wave generation.

  14. Discretized energy minimization in a wave guide with point sources

    Science.gov (United States)

    Propst, G.

    1994-01-01

    An anti-noise problem on a finite time interval is solved by minimization of a quadratic functional on the Hilbert space of square integrable controls. To this end, the one-dimensional wave equation with point sources and pointwise reflecting boundary conditions is decomposed into a system for the two propagating components of waves. Wellposedness of this system is proved for a class of data that includes piecewise linear initial conditions and piecewise constant forcing functions. It is shown that for such data the optimal piecewise constant control is the solution of a sparse linear system. Methods for its computational treatment are presented as well as examples of their applicability. The convergence of discrete approximations to the general optimization problem is demonstrated by finite element methods.

  15. An ultrasonic guided wave approach for the inspection of overhead transmission line cables

    DEFF Research Database (Denmark)

    Yücel, Mehmet K.; Legg, Mathew; Kappatos, Vasileios

    2017-01-01

    as a non-destructive testing technique is well established for simple geometries such as plates, pipes, and rods. However, its application for multi-wire cables is still in development. In this study, ultrasonic guided waves excited by a shear mode transducer collar are utilised as a defect detection...... technique for untensioned aluminium conductor steel reinforced cable specimens. The identification and analysis of wave propagation for a broad range of frequencies is performed using a laser scanning vibrometer, and the effect of defect size on wave propagation is studied. Signal processing algorithms...

  16. Analysis of Defective Pipings in Nuclear Power Plants and Applications of Guided Ultrasonic Wave Techniques

    International Nuclear Information System (INIS)

    Koo, Dae Seo; Cheong, Yong Moo; Jung, Hyun Kyu; Park, Chi Seung; Park, Jae Suck; Choi, H. R.; Jung, S. S.

    2006-07-01

    In order to apply the guided ultrasonic techniques to the pipes in nuclear power plants, the cases of defective pipes of nuclear power plants, were investigated. It was confirmed that geometric factors of pipes, such as location, shape, and allowable space were impertinent for the application of guided ultrasonic techniques to pipes of nuclear power plants. The quality of pipes, supports, signals analysis of weldment/defects, acquisition of accurate defects signals also make difficult to apply the guided ultrasonic techniques to pipes of nuclear power plants. Thus, a piping mock-up representing the pipes in the nuclear power plants were designed and fabricated. The artificial flaws will be fabricated on the piping mock-up. The signals of guided ultrasonic waves from the artificial flaws will be analyzed. The guided ultrasonic techniques will be applied to the inspection of pipes of nuclear power plants according to the basis of signals analysis of artificial flaws in the piping mock-up

  17. The energy transport by the propagation of sound waves in wave guides with a moving medium

    NARCIS (Netherlands)

    le Grand, P.

    1977-01-01

    The problem of the propagation of sound waves radiated by a source in a fluid moving with subsonic velocity between two parallel walls or inside a cylindrical tube is considered in [2], The most interesting thing of this problem is that waves may occur with constant amplitude coming from infinity.

  18. Design and construction of wave guide CO2 laser

    International Nuclear Information System (INIS)

    Al-Ali, M.S.

    1989-01-01

    This thesis describes the design, construction and operation of a countinous wave (CW) CO2 waveguide laser with axial gas flow in which the multi-electrode technique was used to achieve uniform volume of ionized gas using two and four pairs of electrodes. Resonators of lengths ( 26 - 47.5 ) cm with inside diameter ( 3 - 4 ) mm were used with discharge taking place between four pairs of electordes 8.25 cm long each, in axial direction of the tube. The avearge flow at the tube outlet was ( 5 - 6.5 ) L/min at different gas pressures. ( 4 tabs., 74 figs., 58 refs. )

  19. Guided wave imaging of oblique reflecting interfaces in pipes using common-source synthetic focusing

    Science.gov (United States)

    Sun, Zeqing; Sun, Anyu; Ju, Bing-Feng

    2018-04-01

    Cross-mode-family mode conversion and secondary reflection of guided waves in pipes complicate the processing of guided waves signals, and can cause false detection. In this paper, filters operating in the spectral domain of wavenumber, circumferential order and frequency are designed to suppress the signal components of unwanted mode-family and unwanted traveling direction. Common-source synthetic focusing is used to reconstruct defect images from the guided wave signals. Simulations of the reflections from linear oblique defects and a semicircle defect are separately implemented. Defect images, which are reconstructed from the simulation results under different excitation conditions, are comparatively studied in terms of axial resolution, reflection amplitude, detectable oblique angle and so on. Further, the proposed method is experimentally validated by detecting linear cracks with various oblique angles (10-40°). The proposed method relies on the guided wave signals that are captured during 2-D scanning of a cylindrical area on the pipe. The redundancy of the signals is analyzed to reduce the time-consumption of the scanning process and to enhance the practicability of the proposed method.

  20. Guided elastic waves produced by a periodically joined interface in a rock mass

    CSIR Research Space (South Africa)

    Yenwong Fai

    2012-09-01

    Full Text Available on Computational and Applied Mechanics SACAM2012 Johannesburg, South Africa, 3−5 September 2012 c©SACAM Guided Elastic Waves Produced by a Periodically Joined Interface in a Rock Mass A.S. Yenwong Fai School of Physics University of the Witwatersrand Johannesburg...

  1. Damage identification using guided waves on a composite skin-stiffener structure

    NARCIS (Netherlands)

    Loendersloot, R.; Battley, M.; Tinga, T.

    2016-01-01

    The potential of using guided waves for damage detection in composite materials has been proven by many researches in the past few years and in particular by the cases studies of the European project SARISTU. In that project integration methods for the piezoelectric wafer active sensors (PWAS),

  2. Wireless guided wave and impedance measurement using laser and piezoelectric transducers

    International Nuclear Information System (INIS)

    Park, Hyun-Jun; Sohn, Hoon; Yun, Chung-Bang; Chung, Joseph; Lee, Michael M S

    2012-01-01

    Guided-wave- and impedance-based structural health monitoring (SHM) techniques have gained much attention due to their high sensitivity to small defects. One of the popular devices commonly used for guided wave and impedance measurements is a lead zirconate titanate (PZT) transducer. This study proposes a new wireless scheme where the power and data required for PZT excitation and sensing are transmitted via laser. First, a modulated laser beam is wirelessly transmitted to the photodiode connected to a PZT on a structure. Then, the photodiode converts the laser light into an electric signal, and it is applied to the PZT for excitation. The corresponding responses, impedance at the same PZT or guided waves at another PZT, are measured, re-converted into laser light, and wirelessly transmitted back to the other photodiode located in the data interrogator for signal processing. The feasibility of the proposed wireless guided wave and impedance measurement schemes has been examined through circuit analyses and experimentally investigated in a laboratory setup. (paper)

  3. Monitoring of Defects in a Pipe Weld by a Comparison of Magnetostrictive Guided Wave Signals

    International Nuclear Information System (INIS)

    Cheong, Yong-Moo; Oh, Se-Beom; Lee, Duck-Hyun

    2016-01-01

    In this study a computer program for an accurate comparison and subtraction of guided wave signals were developed. The program contains an algorithm for calibration with the flight time and phases of ultrasonic signals in the time domain. Once the reference signals were acquired at the beginning of the monitoring, the signals can be compared to the reference. The signals due to the geometry can be eliminated clearly and an evolution of defect in a pipe can be monitored accurately. In order to improve the detectability and solve the problems of the guided wave methods, a magnetostrictive guided wave sensor technique was proposed. Because the waveforms by the magnetostrictive sensors are quite clear and repeatable, it is possible to detect the defects at the weld regions or even monitor the small variations of the defects after a permanent installation of the magnetostrictive strip sensors. In order to eliminate the signals from the geometry, such as weld, pipe support, branch connection, a computer algorithm and program were developed. A notch with 1.5% of CSA of the pipe can be detected with increased accuracy. The guided wave monitoring technique developed in this study can be a promising tool for inspection of the pipe with limited accessibility, such as insulated or buried pipe

  4. Monitoring of Defects in a Pipe Weld by a Comparison of Magnetostrictive Guided Wave Signals

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Yong-Moo; Oh, Se-Beom; Lee, Duck-Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In this study a computer program for an accurate comparison and subtraction of guided wave signals were developed. The program contains an algorithm for calibration with the flight time and phases of ultrasonic signals in the time domain. Once the reference signals were acquired at the beginning of the monitoring, the signals can be compared to the reference. The signals due to the geometry can be eliminated clearly and an evolution of defect in a pipe can be monitored accurately. In order to improve the detectability and solve the problems of the guided wave methods, a magnetostrictive guided wave sensor technique was proposed. Because the waveforms by the magnetostrictive sensors are quite clear and repeatable, it is possible to detect the defects at the weld regions or even monitor the small variations of the defects after a permanent installation of the magnetostrictive strip sensors. In order to eliminate the signals from the geometry, such as weld, pipe support, branch connection, a computer algorithm and program were developed. A notch with 1.5% of CSA of the pipe can be detected with increased accuracy. The guided wave monitoring technique developed in this study can be a promising tool for inspection of the pipe with limited accessibility, such as insulated or buried pipe.

  5. Ultrasonic guided wave sensing characteristics of large area thin piezo coating

    Science.gov (United States)

    Rathod, V. T.; Jeyaseelan, A. Antony; Dutta, Soma; Mahapatra, D. Roy

    2017-10-01

    This paper reports on the characterization method and performance enhancement of thin piezo coating for ultrasonic guided wave sensing applications. We deposited the coatings by an in situ slurry coating method and studied their guided wave sensing properties on a one-dimensional metallic beam as a substrate waveguide. The developed piezo coatings show good sensitivity to the longitudinal and flexural modes of guided waves. Sensing voltage due to the guided waves at various different ultrasonic frequencies shows a linear dependence on the thickness of the coating. The coatings also exhibit linear sensor output voltage with respect to the induced dynamic strain magnitude. Diameter/size of the piezo coatings strongly influences the voltage response in relation to the wavelength. The proposed method used a characterization set-up involving coated sensors, reference transducers and an analytical model to estimate the piezoelectric coefficient of the piezo coating. The method eliminates the size dependent effect on the piezo property accurately and gives further insight to design better sensors/filters with respect to frequency/wavelength of interest. The developed coatings will have interesting applications in structural health monitoring (SHM) and internet of things (IOT).

  6. Monitoring of corrosion damage using high-frequency guided ultrasonic waves

    Science.gov (United States)

    Chew, D.; Fromme, P.

    2015-03-01

    Due to adverse environmental conditions corrosion can develop during the life cycle of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the integrity and load bearing capacity of the structure. Structural health monitoring of corrosion damage in difficult to access areas can in principle be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, high frequency guided wave modes were generated that penetrate through the complete thickness of the structure. Wall thickness reduction was induced using accelerated corrosion in a salt water bath. The corrosion damage was monitored based on the effect on the wave propagation and interference of the different modes. The change in the wave interference was quantified based on an analysis in the frequency domain (Fourier transform) and was found to match well with theoretical predictions for the wall thickness loss. High frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

  7. Fatigue crack growth monitoring in multi-layered structures using guided ultrasonic waves

    International Nuclear Information System (INIS)

    Kostson, E; Fromme, P

    2009-01-01

    This contribution investigates the application of low frequency guided ultrasonic waves for monitoring fatigue crack growth at fastener holes in the 2nd layer of multi-layered plate structures, a common problem in aerospace industry. The model multi-layered structure investigated consists of two aluminum plate-strips adhesively bonded using a structural paste adhesive. Guided ultrasonic waves were excited using multiple piezoelectric discs bonded to the surface of the multi-layered structure. The wave propagation in the tensile specimen was measured using a laser interferometer and compared to numerical simulations. Thickness and width mode shapes of the excited flexural waves were identified from Semi-Analytical Finite Element (SAFE) calculations. Experiments and 3D Finite Element (FE) simulations show a change in the scattered field around fastener holes caused by a defect in the 2nd layer. The amplitude of the guided ultrasonic wave was monitored during fatigue experiments at a single point. The measured changes in the amplitude of the ultrasonic signal due to fatigue crack growth agree well with FE simulations.

  8. A cdk1 gradient guides surface contraction waves in oocytes.

    Science.gov (United States)

    Bischof, Johanna; Brand, Christoph A; Somogyi, Kálmán; Májer, Imre; Thome, Sarah; Mori, Masashi; Schwarz, Ulrich S; Lénárt, Péter

    2017-10-11

    Surface contraction waves (SCWs) in oocytes and embryos lead to large-scale shape changes coupled to cell cycle transitions and are spatially coordinated with the cell axis. Here, we show that SCWs in the starfish oocyte are generated by a traveling band of myosin II-driven cortical contractility. At the front of the band, contractility is activated by removal of cdk1 inhibition of the RhoA/RhoA kinase/myosin II signaling module, while at the rear, contractility is switched off by negative feedback originating downstream of RhoA kinase. The SCW's directionality and speed are controlled by a spatiotemporal gradient of cdk1-cyclinB. This gradient is formed by the release of cdk1-cyclinB from the asymmetrically located nucleus, and progressive degradation of cyclinB. By combining quantitative imaging, biochemical and mechanical perturbations with mathematical modeling, we demonstrate that the SCWs result from the spatiotemporal integration of two conserved regulatory modules, cdk1-cyclinB for cell cycle regulation and RhoA/Rok/NMYII for actomyosin contractility.Surface contraction waves (SCWs) are prominent shape changes coupled to cell cycle transitions in oocytes. Here the authors show that SCWs are patterned by the spatiotemporal integration of two conserved modules, cdk1-cyclinB for cell cycle regulation and RhoA/Rok/NMYII for actomyosin contractility.

  9. SIMPLE MODELS OF THREE COUPLED PT -SYMMETRIC WAVE GUIDES ALLOWING FOR THIRD-ORDER EXCEPTIONAL POINTS

    Directory of Open Access Journals (Sweden)

    Jan Schnabel

    2017-12-01

    Full Text Available We study theoretical models of three coupled wave guides with a PT-symmetric distribution of gain and loss. A realistic matrix model is developed in terms of a three-mode expansion. By comparing with a previously postulated matrix model it is shown how parameter ranges with good prospects of finding a third-order exceptional point (EP3 in an experimentally feasible arrangement of semiconductors can be determined. In addition it is demonstrated that continuous distributions of exceptional points, which render the discovery of the EP3 difficult, are not only a feature of extended wave guides but appear also in an idealised model of infinitely thin guides shaped by delta functions.

  10. Mode Selection for Axial Flaw Detection in Steam Generator Tube Using Ultrasonic Guided Wave

    International Nuclear Information System (INIS)

    Yoon, Byung Sik; Yang, Seung Han; Guon, Ki Il; Kim, Yong Sik

    2009-01-01

    The eddy current testing method is mainly used to inspect steam generator tube during in-service inspection period. But the general problem of assessing the structural integrity of the steam generator tube using eddy current inspection is rather complex due to the presence of noise and interference signal under various conditions. However, ultrasonic testing as a nondestructive testing tool has become quite popular and effective for the flaw detection and material characterization. Currently, ultrasonic guided wave is emerging technique in power industry because of its various merits. But most of previous studies are focused on detection of circumferential oriented flaws. In this study, the steam generator tube of nuclear power plant was selected to detect axially oriented flaws and investigate guided wave mode identification. The longitudinal wave mode is generated using piezoelectric transducer frequency from 0.5 MHz, 1.0 MHz, 2.25MHz and 5MHz. Dispersion based STFT algorithm is used as mode identification tool

  11. Time-Averaged Adiabatic Potentials: Versatile Matter-Wave Guides and Atom Traps

    International Nuclear Information System (INIS)

    Lesanovsky, Igor; Klitzing, Wolf von

    2007-01-01

    We demonstrate a novel class of trapping potentials, time-averaged adiabatic potentials (TAAP), which allows the generation of a large variety of traps for quantum gases and matter-wave guides for atom interferometers. Examples include stacks of pancakes, rows of cigars, and multiple rings or sickles. The traps can be coupled through controllable tunneling barriers or merged altogether. We present analytical expressions for pancake-, cigar-, and ring-shaped traps. The ring geometry is of particular interest for guided matter-wave interferometry as it provides a perfectly smooth waveguide of widely tunable diameter and thus adjustable sensitivity of the interferometer. The flexibility of the TAAP would make possible the use of Bose-Einstein condensates as coherent matter waves in large-area atom interferometers

  12. Anomalous Refraction of Acoustic Guided Waves in Solids with Geometrically Tapered Metasurfaces.

    Science.gov (United States)

    Zhu, Hongfei; Semperlotti, Fabio

    2016-07-15

    The concept of a metasurface opens new exciting directions to engineer the refraction properties in both optical and acoustic media. Metasurfaces are typically designed by assembling arrays of subwavelength anisotropic scatterers able to mold incoming wave fronts in rather unconventional ways. The concept of a metasurface was pioneered in photonics and later extended to acoustics while its application to the propagation of elastic waves in solids is still relatively unexplored. We investigate the design of acoustic metasurfaces to control elastic guided waves in thin-walled structural elements. These engineered discontinuities enable the anomalous refraction of guided wave modes according to the generalized Snell's law. The metasurfaces are made out of locally resonant toruslike tapers enabling an accurate phase shift of the incoming wave, which ultimately affects the refraction properties. We show that anomalous refraction can be achieved on transmitted antisymmetric modes (A_{0}) either when using a symmetric (S_{0}) or antisymmetric (A_{0}) incident wave, the former clearly involving mode conversion. The same metasurface design also allows achieving structure embedded planar focal lenses and phase masks for nonparaxial propagation.

  13. Assessment of decay in standing timber using stress wave timing nondestructive evaluation tools : a guide for use and interpretation

    Science.gov (United States)

    Xiping Wang; Ferenc Divos; Crystal Pilon; Brian K. Brashaw; Robert J. Ross; Roy F. Pellerin

    2004-01-01

    This guide was prepared to assist field foresters in the use of stress wave timing instruments to locate and define areas of decay in standing timber. The first three sections provide background information, the principles of stress wave nondestructive testing, and measurement techniques for stress wave nondestructive testing. The last section is a detailed description...

  14. Prediction and near-field observation of skull-guided acoustic waves.

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2017-06-21

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. We observed a skull-guided wave propagation over a lateral distance of at least 3 mm, with a half-decay length in the direction perpendicular to the skull ranging from 35 to 300 μm at 6 and 0.5 MHz, respectively. Propagation losses are mostly attributed to the heterogenous acoustic properties of the skull. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  15. Application of a Magnetostrictive Guided wave Technique to Monitor the Evolution of Defect Signals

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Yong-Moo; Oh, Se-Beom; Lee, Duck-Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    An advantage of a magnetostrictive strip transducer for a long-range guided wave inspection is that wave patterns are clear and simple when compared to a conventional piezoelectric ultrasonic transducer. Therefore, if we can characterize the evolution of defect signals, it could be a promising tool for a structural health monitoring of pipes for a long period of time as well as an identification of flaw. Of course, when evaluating a signal during a realistic field examination, it should be careful because of some spurious signals or false indications, such as signals due to a directionality, multiple reflections, mode conversion, geometrical reflections etc. Therefore, the different frequency components of the guided waves will travel at different speeds and the shape of the received signal will changed as it propagates along the pipe. Once the magnetostrictive sensors are attached in the pipe permanently and the signal shape and phase can be compared to the signals before and after, we can monitor the evolution of the flow for the given period. We developed a program to subtract the guided wave signal. The program has a capability of adjusting the time scale and can minimize the noise level after subtraction. By applying the newly developed program, a notch with 2% of CSA can be detected with increased accuracy with noise reduction.

  16. Prediction and near-field observation of skull-guided acoustic waves

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2017-06-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. We observed a skull-guided wave propagation over a lateral distance of at least 3 mm, with a half-decay length in the direction perpendicular to the skull ranging from 35 to 300 μm at 6 and 0.5 MHz, respectively. Propagation losses are mostly attributed to the heterogenous acoustic properties of the skull. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  17. ISIS Topside-Sounder Plasma-Wave Investigations as Guides to Desired Virtual Wave Observatory (VWO) Data Search Capabilities

    Science.gov (United States)

    Benson, Robert F.; Fung, Shing F.

    2008-01-01

    Many plasma-wave phenomena, observed by space-borne radio sounders, cannot be properly explained in terms of wave propagation in a cold plasma consisting of mobile electrons and infinitely massive positive ions. These phenomena include signals known as plasma resonances. The principal resonances at the harmonics of the electron cyclotron frequency, the plasma frequency, and the upper-hybrid frequency are well explained by the warm-plasma propagation of sounder-generated electrostatic waves, Other resonances have been attributed to sounder-stimulated plasma instability and non-linear effects, eigenmodes of cylindrical electromagnetic plasma oscillations, and plasma memory processes. Data from the topside sounders of the International Satellites for Ionospheric Studies (ISIS) program played a major role in these interpretations. A data transformation and preservation effort at the Goddard Space Flight Center has produced digital ISIS topside ionograms and a metadata search program that has enabled some recent discoveries pertaining to the physics of these plasma resonances. For example, data records were obtained that enabled the long-standing question (several decades) of the origin of the plasma resonance at the fundamental electron cyclotron frequency to be explained [Muldrew, Radio Sci., 2006]. These data-search capabilities, and the science enabled by them, will be presented as a guide to desired data search capabilities to be included in the Virtual Wave Observatory (VWO).

  18. Theoretical comparison of light scattering and guided wave coupling in multilayer coated optical components with random interface roughness

    International Nuclear Information System (INIS)

    Elson, J.M.

    1995-01-01

    In this work, we use first-order perturbation theory to calculate and then compare the (1) angular distribution of incident light scattered from a multilayer-coated optical component and (2) the angular distribution of incident light coupled into guided waves supported by the multilayer component. The incident beam is assumed to be a monochromatic plane wave and the scattering/coupling is assumed to be caused by roughness at the interfaces of the optical component. Numerical results show that for high quality (low root mean square roughness) optical components, comparison of the relative amounts of incident energy (1) scattered out of the specular beam and (2) coupled into guided waves are comparable. It follows that the guided wave energy will further contribute to the scattered field via radiative decay or be converted to heat. Thus, this work can help provide an estimation of when guided wave coupling can occur along with the expected magnitude. (orig.)

  19. Laser-based linear and nonlinear guided elastic waves at surfaces (2D) and wedges (1D).

    Science.gov (United States)

    Hess, Peter; Lomonosov, Alexey M; Mayer, Andreas P

    2014-01-01

    The characteristic features and applications of linear and nonlinear guided elastic waves propagating along surfaces (2D) and wedges (1D) are discussed. Laser-based excitation, detection, or contact-free analysis of these guided waves with pump-probe methods are reviewed. Determination of material parameters by broadband surface acoustic waves (SAWs) and other applications in nondestructive evaluation (NDE) are considered. The realization of nonlinear SAWs in the form of solitary waves and as shock waves, used for the determination of the fracture strength, is described. The unique properties of dispersion-free wedge waves (WWs) propagating along homogeneous wedges and of dispersive wedge waves observed in the presence of wedge modifications such as tip truncation or coatings are outlined. Theoretical and experimental results on nonlinear wedge waves in isotropic and anisotropic solids are presented. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Supratentorial CNS malformations

    International Nuclear Information System (INIS)

    Zlatareva, D.

    2012-01-01

    Full text: Clinical suspicion of a developmental anomaly of the central nervous system (CNS) is a frequent indication for performing and magnetic resonance imaging (MRI) examination of the brain. Classification systems for malformation of the CNS are constantly revised according to newer scientific research. Developmental abnormalities can be classified in two main types. The first category consists of disorders of organogenesis in which genetic defects or any ischemic, metabolic, toxic or infectious insult to the developing brain can cause malformation. These malformations result from abnormal neuronal and glial proliferation and from anomalies of neuronal migration and or cortical organization. They are divided into supra- and infratentorial and may involve grey or white matter or both. The second category of congenital brain abnormalities is disorders of histogenesis which result from abnormal cell differentiation with a relatively normal brain appearance. Supratentorial CNS malformations could be divided into anomalies in telencephalic commissure, holoprosencephalies and malformations in cortical development. There are three main telencephalic commissures: the anterior commissure, the hippocampal commissure and the corpus callosum. Their morphology (hypoplasia, hyperplasia, agenesis, dysgenesis, even atrophy) reflects the development of the brain. Their agenesis, complete or partial, is one of the most commonly observed features in the malformations of the brain and is a part of many syndromes. Malformations of cortical development (MCD) are heterogeneous group of disease which result from disruption of 3 main stages of cortical development. The common clinical presentation is refractory epilepsy and or developmental delay. The most common MCD are heterotopias, focal cortical dysplasia, polymicrogyria, schizencephaly, pachygyria and lizencephaly. The exact knowledge of the brain anatomy and embryology is mandatory to provide a better apprehension of the

  1. Using PVDF for wavenumber-frequency analysis and excitation of guided waves

    Science.gov (United States)

    Ren, Baiyang; Cho, Hwanjeong; Lissenden, Cliff J.

    2018-04-01

    The role of transducers in nondestructive evaluation using ultrasonic guided waves cannot be overstated. Energy conversion from electrical to mechanical for actuation and then back to electrical for signal processing broadly describes transduction, but there are many other aspects of transducers that determine their effectiveness. Recently we have reported on polyvinylidene difluoride (PVDF) array sensors that enable determination of the wavenumber spectrum, which enables modal content in the received signal to be characterized. Modal content is an important damage indicator because, for example, mode conversion is a frequent consequence of wave interaction with defects. Some of the positive attributes of PVDF sensors are: broad frequency bandwidth, compliance for use on curved surfaces, limited influence on the passing wave, minimal cross-talk between elements, low profile, low mass, and inexpensive. The anisotropy of PVDF films also enables them to receive either Lamb waves or shear horizontal waves by proper alignment of the material principal coordinate axes. Placing a patterned set of electrodes on the PVDF film provides data from an array of elements. A linear array of elements is used to enable a 2D fast Fourier transform to determine the wavenumber spectrum of both Lamb waves and shear horizontal waves in an aluminum plate. Moreover, since PVDF film can sustain high voltage excitation, high power pulsers can be used to improve the signal-to-noise ratio. The capability of PVDF as a transmitter has been demonstrated with high voltage excitation.

  2. Traveling Wave-Guide Channels of a New Coupled Integrable Dispersionless System

    International Nuclear Information System (INIS)

    Souleymanou, Abbagari; Kuetche, Victor K.; Bouetou, Thomas B.; Kofane, Timoleon C.

    2012-01-01

    In the wake of the recent investigation of new coupled integrable dispersionless equations by means of the Darboux transformation [Zhaqilao, et al., Chin. Phys. B 18 (2009) 1780], we carry out the initial value analysis of the previous system using the fourth-order Runge-Kutta's computational scheme. As a result, while depicting its phase portraits accordingly, we show that the above dispersionless system actually supports two kinds of solutions amongst which the localized traveling wave-guide channels. In addition, paying particular interests to such localized structures, we construct the bilinear transformation of the current system from which scattering amongst the above waves can be deeply studied. (general)

  3. Coherent versus incoherent dynamics in InAs quantum-dot active wave guides

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, W.; Hvam, Jørn Märcher

    2001-01-01

    Coherent dynamics measured by time-resolved four-wave mixing is compared to incoherent population dynamics measured by differential transmission spectroscopy on the ground-state transition at room temperature of two types of InAs-based quantum dots with different confinement energies. The measure....... The measurements are performed with heterodyne detection on quantum-dot active wave guides to enhance the light-matter interaction length. An elastic nature of the measured dephasing is revealed which is independent of the dot energy level scheme....

  4. Design and Implementation of an Electronic Front-End Based on Square Wave Excitation for Ultrasonic Torsional Guided Wave Viscosity Sensor

    Directory of Open Access Journals (Sweden)

    Amir Rabani

    2016-10-01

    Full Text Available The market for process instruments generally requires low cost devices that are robust, small in size, portable, and usable in-plant. Ultrasonic torsional guided wave sensors have received much attention by researchers for measurement of viscosity and/or density of fluids in recent years. The supporting electronic systems for these sensors providing many different settings of sine-wave signals are bulky and expensive. In contrast, a system based on bursts of square waves instead of sine waves would have a considerable advantage in that respect and could be built using simple integrated circuits at a cost that is orders of magnitude lower than for a windowed sine wave device. This paper explores the possibility of using square wave bursts as the driving signal source for the ultrasonic torsional guided wave viscosity sensor. A simple design of a compact and fully automatic analogue square wave front-end for the sensor is also proposed. The successful operation of the system is demonstrated by using the sensor for measuring the viscosity in a representative fluid. This work provides the basis for design and manufacture of low cost compact standalone ultrasonic guided wave sensors and enlightens the possibility of using coded excitation techniques utilising square wave sequences in such applications.

  5. Comparison of a magnetostrictive and an EMAT guided wave technique for the long-range pipe inspection

    International Nuclear Information System (INIS)

    Jung Yong Moo; Kim, Sang Soo; Kim, Young Suk

    2005-01-01

    An EMAT sensor and a magnetostrictive sensor were developed for the long-range guided wave inspection of pipe. An array of EMAT were designed and fabricated for the generation and reception of torsional guided waves. Also a magnetostrictive sensor with a circumferentially magnetized Ni strip and coil for alternating magnetization were fabricated for torsional guided waves, T(0,1) mode. These two approaches were applied to the feeder pipe with various artificial notches. The advantages and limitations of the EMAT method and magnetostrictive method compared in the viewpoint of field application.

  6. Guided Wave Sensing In a Carbon Steel Pipe Using a Laser Vibrometer System

    Science.gov (United States)

    Ruíz Toledo, Abelardo; Salazar Soler, Jordi; Chávez Domínguez, Juan Antonio; García Hernández, Miguel Jesús; Turó Peroy, Antoni

    2010-05-01

    Non-Destructive Evaluation (NDE) techniques have achieved a great development during the last decades as a valuable tool for material characterization, manufacturing control and structural integrity tests. Among these tools, the guided wave technology has been rapidly extended because it reduces inspection time and costs compared to the ordinary point by point testing in large structures, as well as because of the possibility of inspecting under insulation and coating conditions. This fast development has motivated the creation of several inspection and material characterization systems including different technologies which can be combined with this technique. Different measurements systems based on laser techniques have been presented in order to inspect pipes, plates and diverse structures. Many of them are experimental systems of high cost and complexity which combine the employment of a laser for generation of waves in the structure and an interferometer for detection. Some of them employ air-coupled ultrasound generation transducers, with high losses in air and which demand high energy for exciting waves in materials of high stiffness. The combined employment of a commercial vibrometer system for Lamb wave sensing in plates has been successfully shown in the literature. In this paper we present a measurement system based on the combined employment of a piezoelectric wedge transducer and a laser vibrometer to sense guided acoustic waves in carbon steel pipes. The measurement system here presented is mainly compounded of an angular wedge transducer, employed to generate the guided wave and a commercial laser vibrometer used in the detection process. The wedge transducer is excited by means of a signal function generator whose output signal has been amplified with a power signal amplifier. A high precision positioning system is employed to place the laser beam at different points through the pipe surface. The signal detected by the laser vibrometer system is

  7. Guided wave mode selection for inhomogeneous elastic waveguides using frequency domain finite element approach.

    Science.gov (United States)

    Chillara, Vamshi Krishna; Ren, Baiyang; Lissenden, Cliff J

    2016-04-01

    This article describes the use of the frequency domain finite element (FDFE) technique for guided wave mode selection in inhomogeneous waveguides. Problems with Rayleigh-Lamb and Shear-Horizontal mode excitation in isotropic homogeneous plates are first studied to demonstrate the application of the approach. Then, two specific cases of inhomogeneous waveguides are studied using FDFE. Finally, an example of guided wave mode selection for inspecting disbonds in composites is presented. Identification of sensitive and insensitive modes for defect inspection is demonstrated. As the discretization parameters affect the accuracy of the results obtained from FDFE, effect of spatial discretization and the length of the domain used for the spatial fast Fourier transform are studied. Some recommendations with regard to the choice of the above parameters are provided. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Application of the Guided Wave Technique to the Heat Exchanger Tube in NPP

    International Nuclear Information System (INIS)

    Yang, Dong Soon; Kim, Hyung Nam; Yoo, Hyun Joo

    2005-01-01

    The heat exchanger tube is examined by the method of eddy current test(ECT) to identify the integrity of the nuclear power plant. Because ECT probe is moved through the tube inside to identify flaws, the ECT probe should be exchanged periodically due to the wear of probe surface in order to remove the noise form the ECT signal. Moreover, it is impossible to examine the tube by ECT method because the ECT probe can not move through the inside due to the deformation such as dent. Recently, the theory of guided wave was established and the equipment applying the theory has been actively developed so as to overcome the limitation of ECT method for the tube inspection of heater exchanger in nuclear power plant. The object of this study is to know the application of the guided wave technique to heat exchanger tube in NPP

  9. Feasibility study on the guided wave technique for condenser tube in NPP

    International Nuclear Information System (INIS)

    Choi, Sung Nam; Kim, Young Ho; Kim, Hyung Nam; Yoo, Hyun Joo; Hwang, W. G.

    2004-01-01

    The condenser tube is examined by the eddy current test (ECT) method to identify the integrity of the nuclear power plant. Because ECT probe is moved through the tube inside to identify flaws, the ECT probe should be exchanged periodically due to the wear of probe surface in order to remove the noise form the ECT signal. Moreover, it is impossible to examine the tube by ECT method because the ECT probe can not move through the inside due to the deformation such as dent. Recently, the theory of guided wave was established and the equipment applying the theory has been actively developed so as to overcome the limitation of ECT method for the tube inspection of heater exchanger in nuclear power plant. The object of this study is to know the feasibility of applying the guided wave technique to condenser tube in NPP

  10. Monitoring of corrosion damage using high-frequency guided ultrasonic waves

    OpenAIRE

    Chew, D.; Fromme, P.

    2014-01-01

    Due to adverse environmental conditions corrosion can develop during the life cycle of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the integrity and load bearing capacity of the structure. Structural health monitoring of corrosion damage in difficult to access areas can in principle be achieved using high frequency guided waves propagating along...

  11. Detection of CFRP Composite Manufacturing Defects Using a Guided Wave Approach

    Science.gov (United States)

    Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.; Yuan, Fuh-Gwo

    2015-01-01

    NASA Langley Research Center is investigating a guided-wave based defect detection technique for as-fabricated carbon fiber reinforced polymer (CFRP) composites. This technique will be extended to perform in-process cure monitoring, defect detection and size determination, and ultimately a closed-loop process control to maximize composite part quality and consistency. The overall objective of this work is to determine the capability and limitations of the proposed defect detection technique, as well as the number and types of sensors needed to identify the size, type, and location of the predominant types of manufacturing defects associated with laminate layup and cure. This includes, porosity, gaps, overlaps, through-the-thickness fiber waviness, and in-plane fiber waviness. The present study focuses on detection of the porosity formed from variations in the matrix curing process, and on local overlaps intentionally introduced during layup of the prepreg. By terminating the cycle prematurely, three 24-ply unidirectional composite panels were manufactured such that each subsequent panel had a higher final degree of cure, and lower level of porosity. It was demonstrated that the group velocity, normal to the fiber direction, of a guided wave mode increased by 5.52 percent from the first panel to the second panel and 1.26 percent from the second panel to the third panel. Therefore, group velocity was utilized as a metric for degree of cure and porosity measurements. A fully non-contact guided wave hybrid system composed of an air-coupled transducer and a laser Doppler vibrometer (LDV) was used for the detection and size determination of an overlap By transforming the plate response from the time-space domain to the frequency-wavenumber domain, the total wavefield was then separated into the incident and backscatter waves. The overlap region was accurately imaged by using a zero-lag cross-correlation (ZLCC) imaging condition, implying the incident and backscattered

  12. Simulation of Guided Wave Interaction with In-Plane Fiber Waviness

    Science.gov (United States)

    Leckey, Cara A. C.; Juarez, Peter D.

    2016-01-01

    Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness.

  13. HTS-SQUID NDE Technique for Pipes based on Ultrasonic Guided Wave

    International Nuclear Information System (INIS)

    Hatsukade, Y; Masutani, N; Teranishi, S; Masamoto, K; Kanenaga, S; Adachi, S; Tanabe, K

    2017-01-01

    This article describes research on the novel high-temperature superconductor (HTS) superconducting quantum interference device (SQUID) non-destructive evaluation (NDE) technique for metallic pipes based on ultrasonic guided waves. We constructed HTS-SQUID NDE system for pipes based on ultrasonic guided waves, which were generated and received by means of the magnetostrictive effects. Using the system, we measured magnetic signals due to T (0, 1) mode ultrasonic guided waves that transmitted on aluminium pipe, and investigated influences of measurement parameters to the magnetic signals, such as direction of a HTS-SQUID gradiometer, lift-off distance, and intensity and frequency of input current fed to a magnetostrictive transmitter. With the gradiometer oriented parallel to the pipe axis, more than 10 times larger signals were measured compared with that oriented perpendicular to the pipe axis. Magnetic signals measured by the gradiometer were inverse proportional to the power of the list- off distance, and proportional to the intensity of the input current up to 1 A pp . Relation between the frequency of the input current and the measured signal was shown and discussed. (paper)

  14. Monitoring of fatigue damage in composite lap-joints using guided waves and FBG sensors

    Science.gov (United States)

    Karpenko, Oleksii; Khomenko, Anton; Koricho, Ermias; Haq, Mahmoodul; Udpa, Lalita

    2016-02-01

    Adhesive bonding is being increasingly employed in many applications as it offers possibility of light-weighting and efficient multi-material joining along with reduction in time and cost of manufacturing. However, failure initiation and progression in critical components like joints, specifically in fatigue loading is not well understood, which necessitates reliable NDE and SHM techniques to ensure structural integrity. In this work, concurrent guided wave (GW) and fiber Bragg grating (FBG) sensor measurements were used to monitor fatigue damage in adhesively bonded composite lap-joints. In the present set-up, one FBG sensor was strategically embedded in the adhesive bond-line of a lap-joint, while two other FBGs were bonded on the surface of the adherends. Full spectral responses of FBG sensors were collected and compared at specific intervals of fatigue loading. In parallel, guided waves were actuated and sensed using PZT wafers mounted on the composite adherends. Experimental results demonstrated that time-of-flight (ToF) of the fundamental modes transmitted through the bond-line and spectral response of FBG sensors were sensitive to fatigue loading and damage. Combination of guided wave and FBG measurements provided the desired redundancy and synergy in the data to evaluate the degradation in bond-line properties. Measurements taken in the presence of continuously applied load replicated the in-situ/service conditions. The approach shows promise in understanding the behavior of bonded joints subjected to complex loading.

  15. Ultrasonic Guided Wave Method For Crack Detection In Buried Plastic Pipe

    Directory of Open Access Journals (Sweden)

    Wan Hamat Wan Sofian

    2016-01-01

    Full Text Available Plastic pipe are widely used in many fields for the fluid or gaseous product conveyance but basic components of a plastic material made it very sensitive to damage, which requires techniques for detecting damage reliable and efficient. Ultrasonic guided wave is a sensitive method based on propagation of low-frequency excitation in solid structures for damage detection. Ultrasonic guided wave method are performed to investigate the effect of crack to the frequency signal using Fast Fourier Transform (FFT analysis. This paper researched to determine performance of ultrasonic guided wave method in order to detect crack in buried pipeline. It was found that for an uncrack pipe, FFT analysis shows one peak which is the operating frequency by the piezoelectric actuator itself while the FFT analysis for single cracked pipe shows two peak which is the operating frequency by the piezoelectric actuator itself and the resultant frequency from the crack. For multi cracked pipe, the frequency signal shows more than two peak depend the number of crack. The results presented here may facilitate improvements in the accuracy and precision of pipeline crack detection.

  16. PPM-based System for Guided Waves Communication Through Corrosion Resistant Multi-wire Cables

    Science.gov (United States)

    Trane, G.; Mijarez, R.; Guevara, R.; Pascacio, D.

    Novel wireless communication channels are a necessity in applications surrounded by harsh environments, for instance down-hole oil reservoirs. Traditional radio frequency (RF) communication schemes are not capable of transmitting signals through metal enclosures surrounded by corrosive gases and liquids. As an alternative to RF, a pulse position modulation (PPM) guided waves communication system has been developed and evaluated using a corrosion resistant 4H18 multi-wire cable, commonly used to descend electronic gauges in down-hole oil applications, as the communication medium. The system consists of a transmitter and a receiver that utilizes a PZT crystal, for electrical/mechanical coupling, attached to each extreme of the multi-wire cable. The modulator is based on a microcontroller, which transmits60 kHz guided wave pulses, and the demodulator is based on a commercial digital signal processor (DSP) module that performs real time DSP algorithms. Experimental results are presented, which were obtained using a 1m corrosion resistant 4H18multi-wire cable, commonly used with downhole electronic gauges in the oil sector. Although there was significant dispersion and multiple mode excitations of the transmitted guided wave energy pulses, the results show that data rates on the order of 500 bits per second are readily available employing PPM and simple communications techniques.

  17. Standard practice for guided wave testing of above ground steel pipework using piezoelectric effect transduction

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This practice provides a procedure for the use of guided wave testing (GWT), also previously known as long range ultrasonic testing (LRUT) or guided wave ultrasonic testing (GWUT). 1.2 GWT utilizes ultrasonic guided waves, sent in the axial direction of the pipe, to non-destructively test pipes for defects or other features by detecting changes in the cross-section and/or stiffness of the pipe. 1.3 GWT is a screening tool. The method does not provide a direct measurement of wall thickness or the exact dimensions of defects/defected area; an estimate of the defect severity however can be provided. 1.4 This practice is intended for use with tubular carbon steel or low-alloy steel products having Nominal Pipe size (NPS) 2 to 48 corresponding to 60.3 to 1219.2 mm (2.375 to 48 in.) outer diameter, and wall thickness between 3.81 and 25.4 mm (0.15 and 1 in.). 1.5 This practice covers GWT using piezoelectric transduction technology. 1.6 This practice only applies to GWT of basic pipe configuration. This inc...

  18. HTS-SQUID NDE Technique for Pipes based on Ultrasonic Guided Wave

    Science.gov (United States)

    Hatsukade, Y.; Masutani, N.; Teranishi, S.; Masamoto, K.; Kanenaga, S.; Adachi, S.; Tanabe, K.

    2017-07-01

    This article describes research on the novel high-temperature superconductor (HTS) superconducting quantum interference device (SQUID) non-destructive evaluation (NDE) technique for metallic pipes based on ultrasonic guided waves. We constructed HTS-SQUID NDE system for pipes based on ultrasonic guided waves, which were generated and received by means of the magnetostrictive effects. Using the system, we measured magnetic signals due to T (0, 1) mode ultrasonic guided waves that transmitted on aluminium pipe, and investigated influences of measurement parameters to the magnetic signals, such as direction of a HTS-SQUID gradiometer, lift-off distance, and intensity and frequency of input current fed to a magnetostrictive transmitter. With the gradiometer oriented parallel to the pipe axis, more than 10 times larger signals were measured compared with that oriented perpendicular to the pipe axis. Magnetic signals measured by the gradiometer were inverse proportional to the power of the list- off distance, and proportional to the intensity of the input current up to 1 App. Relation between the frequency of the input current and the measured signal was shown and discussed.

  19. Implication of changing loading conditions on structural health monitoring utilising guided waves

    Science.gov (United States)

    Mohabuth, Munawwar; Kotousov, Andrei; Ng, Ching-Tai; Rose, L. R. Francis

    2018-02-01

    Structural health monitoring systems based on guided waves typically utilise a network of embedded or permanently attached sensors, allowing for the continuous detection of damage remote from a sensor location. The presence of damage is often diagnosed by analysing the residual signals from the structure after subtracting damage-free reference data. However, variations in environmental and operational conditions such as temperature, humidity, applied or thermally-induced stresses affect the measured residuals. A previously developed acoustoelastic formulation is here extended and employed as the basis for a simplified analytical model to estimate the effect of applied or thermally-induced stresses on the propagation characteristics of the fundamental Lamb wave modes. It is noted that there are special combinations of frequency, biaxial stress ratio and direction of wave propagation for which there is no change in the phase velocity of the fundamental anti-symmetric mode. The implication of these results in devising effective strategies to mitigate the effect of stress induced variations in guided-wave damage diagnostics is briefly discussed.

  20. Damage detection strategies for aircraft shell-like structures based on propagation guided elastic waves

    International Nuclear Information System (INIS)

    Zak, A; Ostachowicz, W; Krawczuk, M

    2011-01-01

    Damage of aircraft structural elements in any form always present high risks. Failures of these elements can be caused by various reasons including material fatigue or impact leading to damage initiation and growth. Detection of these failures at their earliest stage of development, estimation of their size and location, are one of the most crucial factors for each damage detection method. Structural health monitoring strategies based on propagation of guided elastic waves in structures and wave interaction with damage related discontinuities are very promising tools that offer not only damage detection capabilities, but are also meant to provide precise information about the state of the structures and their remaining lifetime. Because of that various techniques are employed to simulate and mimic the wave-discontinuity interactions. The use of various types of sensors, their networks together with sophisticated contactless measuring techniques are investigated both numerically and experimentally. Certain results of numerical simulations obtained by the use of the spectral finite element method are presented by the authors and related with propagation of guided elastic waves in shell-type aircraft structures. Two types of structures are considered: flat 2D panels with or without stiffeners and 3D shell structures. The applicability of two different damage detection approaches is evaluated in order to detect and localise damage in these structures. Selected results related with the use of laser scanning vibrometry are also presented and discussed by the authors.

  1. Management of CNS tumors

    International Nuclear Information System (INIS)

    Griem, M.L.

    1987-01-01

    The treatment of tumors of the CNS has undergone a number of changes based on the impact of CT. The use of intraoperative US for the establishment of tumor location and tumor histology is demonstrated. MR imaging also is beginning to make an impact on the diagnosis and treatment of tumors of the CNS. Examples of MR images are shown. The authors then discuss the important aspects of tumor histology as it affects management and newer concepts in surgery, radiation, and chemotherapy on tumor treatment. The role of intraoperative placement of radioactive sources, the utilization of heavy particle radiation therapy, and the potential role of other experimental radiation therapy techniques are discussed. The role of hyperfractionated radiation and of neutrons and x-ray in a mixed-beam treatment are discussed in perspective with standard radiation therapy. Current chemotherapy techniques, including intraarterial chemotherapy, are discussed. The complications of radiation therapy alone and in combination with chemotherapy in the management of primary brain tumors, brain metastases, and leukemia are reviewed. A summary of the current management of pituitary tumors, including secreting pituitary adenomas and chromophobe adenomas, are discussed. The treatment with heavy particle radiation, transsphenoidal microsurgical removal, and combined radiotherapeutic and surgical management are considered. Tumor metastasis management of lesions of the brain and spinal cord are considered

  2. On guided circumferential waves in soft electroactive tubes under radially inhomogeneous biasing fields

    Science.gov (United States)

    Wu, Bin; Su, Yipin; Chen, Weiqiu; Zhang, Chuanzeng

    2017-02-01

    Soft electroactive (EA) tube actuators and many other cylindrical devices have been proposed recently in literature, which show great advantages over those made from conventional hard solid materials. However, their practical applications may be limited because these soft EA devices are prone to various failure modes. In this paper, we present an analysis of the guided circumferential elastic waves in soft EA tube actuators, which has potential applications in the in-situ nondestructive evaluation (NDE) or online structural health monitoring (SHM) to detect structural defects or fatigue cracks in soft EA tube actuators and in the self-sensing of soft EA tube actuators based on the concept of guided circumferential elastic waves. Both circumferential SH and Lamb-type waves in an incompressible soft EA cylindrical tube under inhomogeneous biasing fields are considered. The biasing fields, induced by the application of an electric voltage difference to the electrodes on the inner and outer cylindrical surfaces of the EA tube in addition to an axial pre-stretch, are inhomogeneous in the radial direction. Dorfmann and Ogden's theory of nonlinear electroelasticity and the associated linear theory for small incremental motion constitute the basis of our analysis. By means of the state-space formalism for the incremental wave motion along with the approximate laminate technique, dispersion relations are derived in a particularly efficient way. For a neo-Hookean ideal dielectric model, the proposed approach is first validated numerically. Numerical examples are then given to show that the guided circumferential wave propagation characteristics are significantly affected by the inhomogeneous biasing fields and the geometrical parameters. Some particular phenomena such as the frequency veering and the nonlinear dependence of the phase velocity on the radial electric voltage are discussed. Our numerical findings demonstrate that it is feasible to use guided circumferential

  3. PZT guided waves sensor permanently attached on multi-wire AWG12 cables used as communication medium

    Science.gov (United States)

    Trane, Gianpiero; Mijarez, Rito; Guevara, Ricardo; Baltazar, Arturo

    2015-03-01

    Guided waves in solid media have been used in structural health monitoring (SHM) and non-destructive testing (NDT) applications due to their mechanical propagation properties. In this context, guided waves communications offer the reuse of infrastructure as communication channel, in which the guided waves work as the information carrying signals. This study presents the proprietary design and implementation of a piezoelectric (PZT) sensor for the transmission and reception of guided waves that uses a multiple-wire AWG12 cable, commonly used in electric domestic and industrial applications, as a communication channel. The design involves electrical/mechanical coupling, electric isolation, instrumentation and casing. The PZT guided waves transmitter instrumentation includes a microcontroller-based pulse position modulator (PPM), a signal booster, a PZT crystal and a 9 V battery. Dispersion curves of the cable and dynamical linear 3D finite element (FE) models of the sensor were performed to substantiate the proper frequency selection. To evaluate the transmitter design, a receiver instrumentation package made of a PZT crystal, an amplifier and a commercial data acquisition module connected to a personal computer was implemented. Experimental tests were conducted in the laboratory using 1 m and 4 m AWG12 cables. Results showed that, although there was significant dispersion and multiple mode excitations of the transmitted pulses, the system correctly identified 10-bit frames of guided wave PPM encoded information.

  4. Imaging ultrasonic dispersive guided wave energy in long bones using linear radon transform.

    Science.gov (United States)

    Tran, Tho N H T; Nguyen, Kim-Cuong T; Sacchi, Mauricio D; Le, Lawrence H

    2014-11-01

    Multichannel analysis of dispersive ultrasonic energy requires a reliable mapping of the data from the time-distance (t-x) domain to the frequency-wavenumber (f-k) or frequency-phase velocity (f-c) domain. The mapping is usually performed with the classic 2-D Fourier transform (FT) with a subsequent substitution and interpolation via c = 2πf/k. The extracted dispersion trajectories of the guided modes lack the resolution in the transformed plane to discriminate wave modes. The resolving power associated with the FT is closely linked to the aperture of the recorded data. Here, we present a linear Radon transform (RT) to image the dispersive energies of the recorded ultrasound wave fields. The RT is posed as an inverse problem, which allows implementation of the regularization strategy to enhance the focusing power. We choose a Cauchy regularization for the high-resolution RT. Three forms of Radon transform: adjoint, damped least-squares, and high-resolution are described, and are compared with respect to robustness using simulated and cervine bone data. The RT also depends on the data aperture, but not as severely as does the FT. With the RT, the resolution of the dispersion panel could be improved up to around 300% over that of the FT. Among the Radon solutions, the high-resolution RT delineated the guided wave energy with much better imaging resolution (at least 110%) than the other two forms. The Radon operator can also accommodate unevenly spaced records. The results of the study suggest that the high-resolution RT is a valuable imaging tool to extract dispersive guided wave energies under limited aperture. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  5. Flavonoids and the CNS

    DEFF Research Database (Denmark)

    Jäger, Anna Katharina; Saaby, Lasse

    2011-01-01

    Flavonoids are present in almost all terrestrial plants, where they provide UV-protection and colour. Flavonoids have a fused ring system consisting of an aromatic ring and a benzopyran ring with a phenyl substituent. The flavonoids can be divided into several classes depending on their structure....... Flavonoids are present in food and medicinal plants and are thus consumed by humans. They are found in plants as glycosides. Before oral absorption, flavonoids undergo deglycosylation either by lactase phloridzin hydrolase or cytosolic ß-glucocidase. The absorbed aglycone is then conjugated by methylation......, sulphatation or glucuronidation. Both the aglycones and the conjugates can pass the blood-brain barrier. In the CNS several flavones bind to the benzodiazepine site on the GABA(A)-receptor resulting in sedation, anxiolytic or anti-convulsive effects. Flavonoids of several classes are inhibitors of monoamine...

  6. Simulation of non-destructive inspections and acoustic emission measurements involving guided waves

    International Nuclear Information System (INIS)

    Baronian, V; Lhemery, A; Bonnet-BenDhia, A-S

    2009-01-01

    In a structure that guides elastic waves, a discontinuity (defect, shape variation) causes scattering (reflection, partial extinction or mode conversion). Two modal formulations have been developed to link separate models dealing with the calculation of the modal decomposition, with the generation and reception of guided waves (GW), with their scattering. The first concerns pulse-echo configurations (involving a single transducer), the other concerns pitch-catch configurations (two transducers involved). A new finite element (FE) method has been developed to compute the scattering by an arbitrary discontinuity, based on the modal decomposition of the field. Perfectly transparent boundary conditions (Dirichlet-to-Neuman boundaries) are developed, allowing the FE computation zone to be reduced to a minimum. A specific variational problem including these boundary conditions was obtained and solved using FE tools. By combining the modal formulations, the new FE scheme and tools for GW radiation, propagation and reception based on the Semi-Analytical Finite Element (SAFE) method, a new simulation tool has been developed. It can address almost arbitrary configurations of GW nondestructive testing. Moreover, a source inside the FE computation zone can be defined so that configurations of testing by acoustic emission can also be simulated. Examples of use of this tool are shown, some dealing with junctions of complex geometry between two guides, other with surface or bulk sources of acoustic emission.

  7. PCA Based Stress Monitoring of Cylindrical Specimens Using PZTs and Guided Waves

    Directory of Open Access Journals (Sweden)

    Jabid Quiroga

    2017-12-01

    Full Text Available Since mechanical stress in structures affects issues such as strength, expected operational life and dimensional stability, a continuous stress monitoring scheme is necessary for a complete integrity assessment. Consequently, this paper proposes a stress monitoring scheme for cylindrical specimens, which are widely used in structures such as pipelines, wind turbines or bridges. The approach consists of tracking guided wave variations due to load changes, by comparing wave statistical patterns via Principal Component Analysis (PCA. Each load scenario is projected to the PCA space by means of a baseline model and represented using the Q-statistical indices. Experimental validation of the proposed methodology is conducted on two specimens: (i a 12.7 mm ( 1 / 2 ″ diameter, 0.4 m length, AISI 1020 steel rod, and (ii a 25.4 mm ( 1 ″ diameter, 6m length, schedule 40, A-106, hollow cylinder. Specimen 1 was subjected to axial loads, meanwhile specimen 2 to flexion. In both cases, simultaneous longitudinal and flexural guided waves were generated via piezoelectric devices (PZTs in a pitch-catch configuration. Experimental results show the feasibility of the approach and its potential use as in-situ continuous stress monitoring application.

  8. Parametric Study of Defect Detection in Pipes with Bend Using Guided Ultrasonic Waves

    Directory of Open Access Journals (Sweden)

    Jack Tan Jin

    2016-01-01

    Full Text Available The propagation behaviour of guided ultrasonic waves in a steel pipe with welded bend is studied by finite element simulation. The effectiveness of the longitudinal L(0,2 and torsional T(0,1 guided waves in detecting circumferential cut near the weld is investigated. In order to identify the presence of the defect, the reflection strength due to the cut is studied. The geometry of the weld is constructed based on common V-bevel butt joints and the anisotropy of the 316L stainless steel weld is included to correctly predict the scattering of ultrasonic waves. The finite element model is built to allow high accuracy. Detection of small circumferential cut (up to 60° circumferential extent can be achieved with longitudinal L(0,2 mode. Detection of moderate to large circumferential cut can be achieved by torsional T(0,1 or longitudinal L(0,2 modes, with T(0,1 mode preferred due to its less mode conversion to higher order modes.

  9. Sparse and Dispersion-Based Matching Pursuit for Minimizing the Dispersion Effect Occurring when Using Guided Wave for Pipe Inspection.

    Science.gov (United States)

    Rostami, Javad; Tse, Peter W T; Fang, Zhou

    2017-06-06

    Ultrasonic guided wave is an effective tool for structural health monitoring of structures for detecting defects. In practice, guided wave signals are dispersive and contain multiple modes and noise. In the presence of overlapped wave-packets/modes and noise together with dispersion, extracting meaningful information from these signals is a challenging task. Handling such challenge requires an advanced signal processing tool. The aim of this study is to develop an effective and robust signal processing tool to deal with the complexity of guided wave signals for non-destructive testing (NDT) purpose. To achieve this goal, Sparse Representation with Dispersion Based Matching Pursuit (SDMP) is proposed. Addressing the three abovementioned facts that complicate signal interpretation, SDMP separates overlapped modes and demonstrates good performance against noise with maximum sparsity. With the dispersion taken into account, an overc-omplete and redundant dictionary of basic atoms based on a narrowband excitation signal is designed. As Finite Element Method (FEM) was used to predict the form of wave packets propagating along structures, these atoms have the maximum resemblance with real guided wave signals. SDMP operates in two stages. In the first stage, similar to Matching Pursuit (MP), the approximation improves by adding, a single atom to the solution set at each iteration. However, atom selection criterion of SDMP utilizes the time localization of guided wave reflections that makes a portion of overlapped wave-packets to be composed mainly of a single echo. In the second stage of the algorithm, the selected atoms that have frequency inconsistency with the excitation signal are discarded. This increases the sparsity of the final representation. Meanwhile, leading to accurate approximation, as discarded atoms are not representing guided wave reflections, it simplifies extracting physical meanings for defect detection purpose. To verify the effectiveness of SDMP for

  10. Sparse and Dispersion-Based Matching Pursuit for Minimizing the Dispersion Effect Occurring when Using Guided Wave for Pipe Inspection

    Directory of Open Access Journals (Sweden)

    Javad Rostami

    2017-06-01

    Full Text Available Ultrasonic guided wave is an effective tool for structural health monitoring of structures for detecting defects. In practice, guided wave signals are dispersive and contain multiple modes and noise. In the presence of overlapped wave-packets/modes and noise together with dispersion, extracting meaningful information from these signals is a challenging task. Handling such challenge requires an advanced signal processing tool. The aim of this study is to develop an effective and robust signal processing tool to deal with the complexity of guided wave signals for non-destructive testing (NDT purpose. To achieve this goal, Sparse Representation with Dispersion Based Matching Pursuit (SDMP is proposed. Addressing the three abovementioned facts that complicate signal interpretation, SDMP separates overlapped modes and demonstrates good performance against noise with maximum sparsity. With the dispersion taken into account, an overc-omplete and redundant dictionary of basic atoms based on a narrowband excitation signal is designed. As Finite Element Method (FEM was used to predict the form of wave packets propagating along structures, these atoms have the maximum resemblance with real guided wave signals. SDMP operates in two stages. In the first stage, similar to Matching Pursuit (MP, the approximation improves by adding, a single atom to the solution set at each iteration. However, atom selection criterion of SDMP utilizes the time localization of guided wave reflections that makes a portion of overlapped wave-packets to be composed mainly of a single echo. In the second stage of the algorithm, the selected atoms that have frequency inconsistency with the excitation signal are discarded. This increases the sparsity of the final representation. Meanwhile, leading to accurate approximation, as discarded atoms are not representing guided wave reflections, it simplifies extracting physical meanings for defect detection purpose. To verify the

  11. Periodicity effects on compound waves guided by a thin metal slab sandwiched between two periodically nonhomogeneous dielectric materials

    Science.gov (United States)

    Chiadini, Francesco; Fiumara, Vincenzo; Scaglione, Antonio; Lakhtakia, Akhlesh

    2017-10-01

    Surface-plasmon-polariton waves can be compounded when a sufficiently thin metal layer is sandwiched between two half spaces filled with dissimilar periodically nonhomogeneous dielectric materials. We solved the boundary-value problem for compound waves guided by a layer of a homogeneous and isotropic metal sandwiched between a structurally chiral material (SCM) and a periodically multilayered isotropic dielectric (PMLID) material. We found that the periodicities of the PMLID material and the SCM are crucial to excite a multiplicity of compound guided waves arising from strong coupling between the two interfaces.

  12. A Numerical Study on the Excitation of Guided Waves in Rectangular Plates Using Multiple Point Sources

    Directory of Open Access Journals (Sweden)

    Wenbo Duan

    2017-12-01

    Full Text Available Ultrasonic guided waves are widely used to inspect and monitor the structural integrity of plates and plate-like structures, such as ship hulls and large storage-tank floors. Recently, ultrasonic guided waves have also been used to remove ice and fouling from ship hulls, wind-turbine blades and aeroplane wings. In these applications, the strength of the sound source must be high for scanning a large area, or to break the bond between ice, fouling and plate substrate. More than one transducer may be used to achieve maximum sound power output. However, multiple sources can interact with each other, and form a sound field in the structure with local constructive and destructive regions. Destructive regions are weak regions and shall be avoided. When multiple transducers are used it is important that they are arranged in a particular way so that the desired wave modes can be excited to cover the whole structure. The objective of this paper is to provide a theoretical basis for generating particular wave mode patterns in finite-width rectangular plates whose length is assumed to be infinitely long with respect to its width and thickness. The wave modes have displacements in both width and thickness directions, and are thus different from the classical Lamb-type wave modes. A two-dimensional semi-analytical finite element (SAFE method was used to study dispersion characteristics and mode shapes in the plate up to ultrasonic frequencies. The modal analysis provided information on the generation of modes suitable for a particular application. The number of point sources and direction of loading for the excitation of a few representative modes was investigated. Based on the SAFE analysis, a standard finite element modelling package, Abaqus, was used to excite the designed modes in a three-dimensional plate. The generated wave patterns in Abaqus were then compared with mode shapes predicted in the SAFE model. Good agreement was observed between the

  13. Damage detection in hazardous waste storage tank bottoms using ultrasonic guided waves

    Science.gov (United States)

    Cobb, Adam C.; Fisher, Jay L.; Bartlett, Jonathan D.; Earnest, Douglas R.

    2018-04-01

    Detecting damage in storage tanks is performed commercially using a variety of techniques. The most commonly used inspection technologies are magnetic flux leakage (MFL), conventional ultrasonic testing (UT), and leak testing. MFL and UT typically involve manual or robotic scanning of a sensor along the metal surfaces to detect cracks or corrosion wall loss. For inspection of the tank bottom, however, the storage tank is commonly emptied to allow interior access for the inspection system. While there are costs associated with emptying a storage tank for inspection that can be justified in some scenarios, there are situations where emptying the tank is impractical. Robotic, submersible systems have been developed for inspecting these tanks, but there are some storage tanks whose contents are so hazardous that even the use of these systems is untenable. Thus, there is a need to develop an inspection strategy that does not require emptying the tank or insertion of the sensor system into the tank. This paper presents a guided wave system for inspecting the bottom of double-shelled storage tanks (DSTs), with the sensor located on the exterior side-wall of the vessel. The sensor used is an electromagnetic acoustic transducer (EMAT) that generates and receives shear-horizontal guided plate waves using magnetostriction principles. The system operates by scanning the sensor around the circumference of the storage tank and sending guided waves into the tank bottom at regular intervals. The data from multiple locations are combined using the synthetic aperture focusing technique (SAFT) to create a color-mapped image of the vessel thickness changes. The target application of the system described is inspection of DSTs located at the Hanford site, which are million-gallon vessels used to store nuclear waste. Other vessels whose exterior walls are accessible would also be candidates for inspection using the described approach. Experimental results are shown from tests on multiple

  14. The Use of Guided Waves for Rapid Screening of Chemical Plant Pipework

    International Nuclear Information System (INIS)

    Alleyne, D. N.; Pavlakovic, B.; Lowe, M. J. S.; Cawley, P.

    2002-01-01

    The safe operation of petrochemical plant requires screening of the pipework to ensure that there are no unacceptable levels of corrosion. Unfortunately, each plant has many thousands of metres of pipe, much of which is insulated or inaccessible. Conventional methods such as visual inspection and ultrasonic thickness gauging require access to each point of the pipe which is time consuming and very expensive to achieve. Extensional or torsional ultrasonic guided waves in the pipe wall provide an attractive solution to this problem because they can be excited at one location on the pipe and will propagate many metres along the pipe, returning echoes indicating the presence of corrosion or other pipe features. Guided Ultrasonics Ltd. have now commercialised the technique and this paper describes the basis of the method, together with examples of practical test results and typical application areas

  15. Isolated vasculitis of the CNS

    International Nuclear Information System (INIS)

    Block, F.; Reith, W.

    2000-01-01

    Vasculitis is a rare cause for disease of the CNS. The isolated vasculitis of the CNS is restricted to the CNS whereas other forms of vasculitis affect various organs including the CNS. Headache, encephalopathy, focal deficits and epileptic seizures are the major symptoms suggestive for vasculitis. One major criterion of the isolated vasculitis of the CNS is the lack of evidence for other vasculitis forms or for pathology of other organs. Angiography displays multifocal segmental stenosis of intracranial vessels. MRI demonstrates multiple lesions which in part show enhancement after gadolinium. A definite diagnosis can only be made on the grounds of biopsy from leptomeninges and parenchyma. Therapy consists of corticosteroids and cyclophosphamid. (orig.) [de

  16. Deep rock damage in the San Andreas Fault revealed by P- and S-type fault-zone-guided waves

    Science.gov (United States)

    Ellsworth, William L.; Malin, Peter E.

    2011-01-01

    Damage to fault-zone rocks during fault slip results in the formation of a channel of low seismic-wave velocities. Within such channels guided seismic waves, denoted by Fg, can propagate. Here we show with core samples, well logs and Fg-waves that such a channel is crossed by the SAFOD (San Andreas Fault Observatory at Depth) borehole at a depth of 2.7 km near Parkfield, California, USA. This laterally extensive channel extends downwards to at least half way through the seismogenic crust, more than about 7 km. The channel supports not only the previously recognized Love-type- (FL) and Rayleigh-type- (FR) guided waves, but also a new fault-guided wave, which we name FF. As recorded 2.7 km underground, FF is normally dispersed, ends in an Airy phase, and arrives between the P- and S-waves. Modelling shows that FF travels as a leaky mode within the core of the fault zone. Combined with the drill core samples, well logs and the two other types of guided waves, FF at SAFOD reveals a zone of profound, deep, rock damage. Originating from damage accumulated over the recent history of fault movement, we suggest it is maintained either by fracturing near the slip surface of earthquakes, such as the 1857 Fort Tejon M 7.9, or is an unexplained part of the fault-creep process known to be active at this site.

  17. Diffractive beam shaping, tracking and coupling for wave-guided optical waveguides (WOWs)

    DEFF Research Database (Denmark)

    Villangca, Mark Jayson; Bañas, Andrew Rafael; Aabo, Thomas

    2014-01-01

    techniques to create multiple focal spots that can be coupled into light manipulated WOWs. This is done by using a spatial light modulator to project the necessary phase to generate the multiple coupling light spots. We incorporate a diffractive setup in our Biophotonics Workstation (BWS) and demonstrate......We have previously proposed and demonstrated the targeted-light delivery capability of wave-guided optical waveguides (WOWs). The full strength of this structure-mediated paradigm can be harnessed by addressing multiple WOWs and manipulating them to work in tandem. We propose the use of diffractive...

  18. Tone burst generator for a Non-Destructive Testing system based on ultrasonic guided waves

    OpenAIRE

    Jiménez Sánchez, Daniel

    2011-01-01

    English: This PFC provides a design of a tested and specific tone-burst generator circuit for a Non-Destructive System based on ultrasonid guided waves. This circuit includes a complementary protection circuit for the NDT system working in a pulse-echo configuration. In this paper, a brief state f art about different driving circuits employed in distinct NDE systems is presented. Castellano: El PFC proporciona un diseño electrónico específico y probado de un circuito excitador de salvas (C...

  19. Guided acoustic and optical waves in silicon-on-insulator for Brillouin scattering and optomechanics

    Directory of Open Access Journals (Sweden)

    Christopher J. Sarabalis

    2016-10-01

    Full Text Available We numerically study silicon waveguides on silica showing that it is possible to simultaneously guide optical and acoustic waves in the technologically important silicon on insulator (SOI material system. Thin waveguides, or fins, exhibit geometrically softened mechanical modes at gigahertz frequencies with phase velocities below the Rayleigh velocity in glass, eliminating acoustic radiation losses. We propose slot waveguides on glass with telecom optical frequencies and strong radiation pressure forces resulting in Brillouin gains on the order of 500 and 50 000 W−1m−1 for backward and forward Brillouin scattering, respectively.

  20. Monitoring of Soft Deposition Layers in Liquid-Filled Tubes with Guided Acoustic Waves Excited by Clamp-on Transducers.

    Science.gov (United States)

    Tietze, Sabrina; Singer, Ferdinand; Lasota, Sandra; Ebert, Sandra; Landskron, Johannes; Schwuchow, Katrin; Drese, Klaus Stefan; Lindner, Gerhard

    2018-02-09

    The monitoring of liquid-filled tubes with respect to the formation of soft deposition layers such as biofilms on the inner walls calls for non-invasive and long-term stable sensors, which can be attached to existing pipe structures. For this task a method is developed, which uses an ultrasonic clamp-on device. This method is based on the impact of such deposition layers on the propagation of circumferential guided waves on the pipe wall. Such waves are partly converted into longitudinal compressional waves in the liquid, which are back-converted to guided waves in a circular cross section of the pipe. Validating this approach, laboratory experiments with gelatin deposition layers on steel tubes exhibited a distinguishable sensitivity of both wave branches with respect to the thickness of such layers. This allows the monitoring of the layer growth.

  1. Engineering progress of CNS concept in Hanaro

    International Nuclear Information System (INIS)

    Choi, C.O.; Park, K.N.; Park, S.H.

    1997-01-01

    The Korea Atomic Energy research Institute (KAERI) strives to provide utilizing facilities on and around the Hanaro reactor in order to activate advanced researches by neutron application. As one of the facilities to be installed, the conceptual design work of CNS was started in 1996 with a project schedule of 5 years so that its installation work can be finished by the year 2000. And the major engineering targets of this CNS facility are established for a minimum physical interference with the present facilities of the Hanaro, a reach-out of very-high-gain factors in the cold neutron flux, a simplicity of the maintenance of the facility, and a safety in the operation of the facility as well as the reactor. For the conceptual design of Hanaro CNS, the experience of utilization and production of cold neutron at WWR-M reactor Gatchina, Russia has been used with that of elaborations for PIK reactor in design for neutron guide systems and instruments. (author)

  2. Flavonoids and the CNS

    Directory of Open Access Journals (Sweden)

    Anna K. Jäger

    2011-02-01

    Full Text Available Flavonoids are present in almost all terrestrial plants, where they provide UV-protection and colour. Flavonoids have a fused ring system consisting of an aromatic ring and a benzopyran ring with a phenyl substituent. The flavonoids can be divided into several classes depending on their structure. Flavonoids are present in food and medicinal plants and are thus consumed by humans. They are found in plants as glycosides. Before oral absorption, flavonoids undergo deglycosylation either by lactase phloridzin hydrolase or cytosolic β-glucocidase. The absorbed aglycone is then conjugated by methylation, sulphatation or glucuronidation. Both the aglycones and the conjugates can pass the blood-brain barrier. In the CNS several flavones bind to the benzodiazepine site on the GABAA-receptor resulting in sedation, anxiolytic or anti-convulsive effects. Flavonoids of several classes are inhibitors of monoamine oxidase A or B, thereby working as anti-depressants or to improve the conditions of Parkinson’s patients. Flavanols, flavanones and anthocyanidins have protective effects preventing inflammatory processes leading to nerve injury. Flavonoids seem capable of influencing health and mood.

  3. Design of a high efficiency relativistic backward wave oscillator with low guiding magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaoze; Song, Wei; Tan, Weibing; Zhang, Ligang; Su, Jiancang; Zhu, Xiaoxin; Hu, Xianggang; Shen, Zhiyuan; Liang, Xu; Ning, Qi [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

    2016-07-15

    A high efficiency relativistic backward wave oscillator working at a low guiding magnetic field is designed and simulated. A trapezoidal resonant reflector is used to reduce the modulation field in the resonant reflector to avoid overmodulation of the electron beam which will lead to a large momentum spread and then low conversion efficiency. The envelope of the inner radius of the slow wave structure (SWS) increases stepwise to keep conformal to the trajectory of the electron beam which will alleviate the bombardment of the electron on the surface of the SWS. The length of period of the SWS is reduced gradually to make a better match between phase velocity and electron beam, which decelerates continually and improves the RF current distribution. Meanwhile the modulation field is reduced by the introduction of nonuniform SWS also. The particle in cell simulation results reveal that a microwave with a power of 1.8 GW and a frequency of 14.7 GHz is generated with an efficiency of 47% when the diode voltage is 620 kV, the beam current 6.1 kA, and the guiding magnetic field 0.95 T.

  4. Assessment of wall-thinning in carbon steel pipe by using laser-generated guided wave

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Yong; Cho, Youn Ho; Lee, Joon Hyun [Pusan National University, School of Mechanical Engineering, Busan (Korea, Republic of)

    2010-10-15

    The objective of this research is to estimate the crack location and size of a carbon steel pipe by using a laser ultrasound guided wave for the wall thinning evaluation of an elbow. The wall thinning of the carbon steel pipe is one of the most serious problems in nuclear power plants, especially the wall thinning of the carbon steel elbow caused by Flow-Accelerated Corrosion (FAC). Therefore, a non-destructive inspection method of elbow is essential for the nuclear power plants to operate safely. The specimens used in this study were carbon steel elbows, which represented the main elements of real nuclear power plants. The shape of the wall thinning was an oval with a width of 120mm, a length of 80mm, and a depth of 5mm. The L(0,1) and L(0,2) modes variation of the ultrasound guided wave signal is obtained from the response of the laser generation/air-coupled detection ultrasonic hybrid system represent the characteristics of the defect. The trends of these characteristics and signal processing were use dto estimate the size and location of wall thinning

  5. Ensembles of novelty detection classifiers for structural health monitoring using guided waves

    Science.gov (United States)

    Dib, Gerges; Karpenko, Oleksii; Koricho, Ermias; Khomenko, Anton; Haq, Mahmoodul; Udpa, Lalita

    2018-01-01

    Guided wave structural health monitoring uses sparse sensor networks embedded in sophisticated structures for defect detection and characterization. The biggest challenge of those sensor networks is developing robust techniques for reliable damage detection under changing environmental and operating conditions (EOC). To address this challenge, we develop a novelty classifier for damage detection based on one class support vector machines. We identify appropriate features for damage detection and introduce a feature aggregation method which quadratically increases the number of available training observations. We adopt a two-level voting scheme by using an ensemble of classifiers and predictions. Each classifier is trained on a different segment of the guided wave signal, and each classifier makes an ensemble of predictions based on a single observation. Using this approach, the classifier can be trained using a small number of baseline signals. We study the performance using Monte-Carlo simulations of an analytical model and data from impact damage experiments on a glass fiber composite plate. We also demonstrate the classifier performance using two types of baseline signals: fixed and rolling baseline training set. The former requires prior knowledge of baseline signals from all EOC, while the latter does not and leverages the fact that EOC vary slowly over time and can be modeled as a Gaussian process.

  6. Assessment of wall-thinning in carbon steel pipe by using laser-generated guided wave

    International Nuclear Information System (INIS)

    Kim, Do Yong; Cho, Youn Ho; Lee, Joon Hyun

    2010-01-01

    The objective of this research is to estimate the crack location and size of a carbon steel pipe by using a laser ultrasound guided wave for the wall thinning evaluation of an elbow. The wall thinning of the carbon steel pipe is one of the most serious problems in nuclear power plants, especially the wall thinning of the carbon steel elbow caused by Flow-Accelerated Corrosion (FAC). Therefore, a non-destructive inspection method of elbow is essential for the nuclear power plants to operate safely. The specimens used in this study were carbon steel elbows, which represented the main elements of real nuclear power plants. The shape of the wall thinning was an oval with a width of 120mm, a length of 80mm, and a depth of 5mm. The L(0,1) and L(0,2) modes variation of the ultrasound guided wave signal is obtained from the response of the laser generation/air-coupled detection ultrasonic hybrid system represent the characteristics of the defect. The trends of these characteristics and signal processing were use dto estimate the size and location of wall thinning

  7. Effects of temperature variations on guided waves propagating in composite structures

    Science.gov (United States)

    Shoja, Siavash; Berbyuk, Viktor; Boström, Anders

    2016-04-01

    Effects of temperature on guided waves propagating in composite materials is a well-known problem which has been investigated in many studies. The majority of the studies is focused on effects of high temperature. Understanding the effects of low temperature has major importance in composite structures and components which are operating in cold climate conditions such as e.g. wind turbines operating in cold climate regions. In this study first the effects of temperature variations on guided waves propagating in a composite plate is investigated experimentally in a cold climate chamber. The material is a common material used to manufacture rotor blades of wind turbines. The temperature range is 25°C to -25°C and effects of temperature variations on amplitude and phase shift of the received signal are investigated. In order to apply the effects of lowering the temperature on the received signal, the Baseline Signal Stretch (BSS) method is modified and used. The modification is based on decomposing the signal into symmetric and asymmetric modes and applying two different stretch factors on each of them. Finally the results obtained based on the new method is compared with the results of application of BSS with one stretch factor and experimental measurements. Comparisons show that an improvement is obtained using the BSS with the mode decomposition method at temperature variations of more than 25°C.

  8. Optimization and experimental validation of stiff porous phononic plates for widest complete bandgap of mixed fundamental guided wave modes

    Science.gov (United States)

    Hedayatrasa, Saeid; Kersemans, Mathias; Abhary, Kazem; Uddin, Mohammad; Van Paepegem, Wim

    2018-01-01

    Phononic crystal plates (PhPs) have promising application in manipulation of guided waves for design of low-loss acoustic devices and built-in acoustic metamaterial lenses in plate structures. The prominent feature of phononic crystals is the existence of frequency bandgaps over which the waves are stopped, or are resonated and guided within appropriate defects. Therefore, maximized bandgaps of PhPs are desirable to enhance their phononic controllability. Porous PhPs produced through perforation of a uniform background plate, in which the porous interfaces act as strong reflectors of wave energy, are relatively easy to produce. However, the research in optimization of porous PhPs and experimental validation of achieved topologies has been very limited and particularly focused on bandgaps of flexural (asymmetric) wave modes. In this paper, porous PhPs are optimized through an efficient multiobjective genetic algorithm for widest complete bandgap of mixed fundamental guided wave modes (symmetric and asymmetric) and maximized stiffness. The Pareto front of optimization is analyzed and variation of bandgap efficiency with respect to stiffness is presented for various optimized topologies. Selected optimized topologies from the stiff and compliant regimes of Pareto front are manufactured by water-jetting an aluminum plate and their promising bandgap efficiency is experimentally observed. An optimized Pareto topology is also chosen and manufactured by laser cutting a Plexiglas (PMMA) plate, and its performance in self-collimation and focusing of guided waves is verified as compared to calculated dispersion properties.

  9. System and Method for Measuring the Transfer Function of a Guided Wave Device

    Science.gov (United States)

    Froggatt, Mark E. (Inventor); Erdogan, Turan (Inventor)

    2002-01-01

    A method/system are provided for measuring the NxN scalar transfer function elements for an N-port guided wave device. Optical energy of a selected wavelength is generated at a source and directed along N reference optical paths having N reference path lengths. Each reference optical path terminates in one of N detectors such that N reference signals are produced at the N detectors. The reference signals are indicative of amplitude, phase and frequency of the optical energy carried along the N reference optical paths. The optical energy from the source is also directed to the N-ports of the guided wave device and then on to each of the N detectors such that N measurement optical paths are defined between the source and each of the N detectors. A portion of the optical energy is modified in terms of at least one of the amplitude and phase to produce N modified signals at each of the N detectors. At each of the N detectors, each of the N modified signals is combined with a corresponding one of the N reference signals to produce corresponding N combined signals at each of the N detectors. A total of N(sup 2) measurement signals are generated by the N detectors. Each of the N(sup 2) measurement signals is sampled at a wave number increment (Delta)k so that N(sup 2) sampled signals are produced. The NxN transfer function elements are generated using the N(sup 2) sampled signals. Reference and measurement path length constraints are defined such that the N combined signals at each of the N detectors are spatially separated from one another in the time domain.

  10. Modeling guided wave excitation in plates with surface mounted piezoelectric elements: coupled physics and normal mode expansion

    Science.gov (United States)

    Ren, Baiyang; Lissenden, Cliff J.

    2018-04-01

    Guided waves have been extensively studied and widely used for structural health monitoring because of their large volumetric coverage and good sensitivity to defects. Effectively and preferentially exciting a desired wave mode having good sensitivity to a certain defect is of great practical importance. Piezoelectric discs and plates are the most common types of surface-mounted transducers for guided wave excitation and reception. Their geometry strongly influences the proportioning between excited modes as well as the total power of the excited modes. It is highly desirable to predominantly excite the selected mode while the total transduction power is maximized. In this work, a fully coupled multi-physics finite element analysis, which incorporates the driving circuit, the piezoelectric element and the wave guide, is combined with the normal mode expansion method to study both the mode tuning and total wave power. The excitation of circular crested waves in an aluminum plate with circular piezoelectric discs is numerically studied for different disc and adhesive thicknesses. Additionally, the excitation of plane waves in an aluminum plate, using a stripe piezoelectric element is studied both numerically and experimentally. It is difficult to achieve predominant single mode excitation as well as maximum power transmission simultaneously, especially for higher order modes. However, guidelines for designing the geometry of piezoelectric elements for optimal mode excitation are recommended.

  11. Non-contact radio frequency shielding and wave guiding by multi-folded transformation optics method.

    Science.gov (United States)

    Madni, Hamza Ahmad; Zheng, Bin; Yang, Yihao; Wang, Huaping; Zhang, Xianmin; Yin, Wenyan; Li, Erping; Chen, Hongsheng

    2016-11-14

    Compared with conventional radio frequency (RF) shielding methods in which the conductive coating material encloses the circuits design and the leakage problem occurs due to the gap in such conductive material, non-contact RF shielding at a distance is very promising but still impossible to achieve so far. In this paper, a multi-folded transformation optics method is proposed to design a non-contact device for RF shielding. This "open-shielded" device can shield any object at a distance from the electromagnetic waves at the operating frequency, while the object is still physically open to the outer space. Based on this, an open-carpet cloak is proposed and the functionality of the open-carpet cloak is demonstrated. Furthermore, we investigate a scheme of non-contact wave guiding to remotely control the propagation of surface waves over any obstacles. The flexibilities of such multi-folded transformation optics method demonstrate the powerfulness of the method in the design of novel remote devices with impressive new functionalities.

  12. Development of a Fully Automated Guided Wave System for In-Process Cure Monitoring of CFRP Composite Laminates

    Science.gov (United States)

    Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.; Yaun, Fuh-Gwo

    2016-01-01

    A guided wave-based in-process cure monitoring technique for carbon fiber reinforced polymer (CFRP) composites was investigated at NASA Langley Research Center. A key cure transition point (vitrification) was identified and the degree of cure was monitored using metrics such as amplitude and time of arrival (TOA) of guided waves. Using an automated system preliminarily developed in this work, high-temperature piezoelectric transducers were utilized to interrogate a twenty-four ply unidirectional composite panel fabricated from Hexcel (Registered Trademark) IM7/8552 prepreg during cure. It was shown that the amplitude of the guided wave increased sharply around vitrification and the TOA curve possessed an inverse relationship with degree of cure. The work is a first step in demonstrating the feasibility of transitioning the technique to perform in-process cure monitoring in an autoclave, defect detection during cure, and ultimately a closed-loop process control to maximize composite part quality and consistency.

  13. Peri-Elastodynamic Simulations of Guided Ultrasonic Waves in Plate-Like Structure with Surface Mounted PZT

    Directory of Open Access Journals (Sweden)

    Subir Patra

    2018-01-01

    Full Text Available Peridynamic based elastodynamic computation tool named Peri-elastodynamics is proposed herein to simulate the three-dimensional (3D Lamb wave modes in materials for the first time. Peri-elastodynamics is a nonlocal meshless approach which is a scale-independent generalized technique to visualize the acoustic and ultrasonic waves in plate-like structure, micro-electro-mechanical systems (MEMS and nanodevices for their respective characterization. In this article, the characteristics of the fundamental Lamb wave modes are simulated in a sample plate-like structure. Lamb wave modes are generated using a surface mounted piezoelectric (PZT transducer which is actuated from the top surface. The proposed generalized Peri-elastodynamics method is not only capable of simulating two dimensional (2D in plane wave under plane strain condition formulated previously but also capable of accurately simulating the out of plane Symmetric and Antisymmetric Lamb wave modes in plate like structures in 3D. For structural health monitoring (SHM of plate-like structures and nondestructive evaluation (NDE of MEMS devices, it is necessary to simulate the 3D wave-damage interaction scenarios and visualize the different wave features due to damages. Hence, in addition, to simulating the guided ultrasonic wave modes in pristine material, Lamb waves were also simulated in a damaged plate. The accuracy of the proposed technique is verified by comparing the modes generated in the plate and the mode shapes across the thickness of the plate with theoretical wave analysis.

  14. Peri-Elastodynamic Simulations of Guided Ultrasonic Waves in Plate-Like Structure with Surface Mounted PZT.

    Science.gov (United States)

    Patra, Subir; Ahmed, Hossain; Banerjee, Sourav

    2018-01-18

    Peridynamic based elastodynamic computation tool named Peri-elastodynamics is proposed herein to simulate the three-dimensional (3D) Lamb wave modes in materials for the first time. Peri-elastodynamics is a nonlocal meshless approach which is a scale-independent generalized technique to visualize the acoustic and ultrasonic waves in plate-like structure, micro-electro-mechanical systems (MEMS) and nanodevices for their respective characterization. In this article, the characteristics of the fundamental Lamb wave modes are simulated in a sample plate-like structure. Lamb wave modes are generated using a surface mounted piezoelectric (PZT) transducer which is actuated from the top surface. The proposed generalized Peri-elastodynamics method is not only capable of simulating two dimensional (2D) in plane wave under plane strain condition formulated previously but also capable of accurately simulating the out of plane Symmetric and Antisymmetric Lamb wave modes in plate like structures in 3D. For structural health monitoring (SHM) of plate-like structures and nondestructive evaluation (NDE) of MEMS devices, it is necessary to simulate the 3D wave-damage interaction scenarios and visualize the different wave features due to damages. Hence, in addition, to simulating the guided ultrasonic wave modes in pristine material, Lamb waves were also simulated in a damaged plate. The accuracy of the proposed technique is verified by comparing the modes generated in the plate and the mode shapes across the thickness of the plate with theoretical wave analysis.

  15. CNS infections in immunocompetent patients

    International Nuclear Information System (INIS)

    Hartmann, K.M.; Zimmer, A.; Reith, W.

    2008-01-01

    This article gives a review of the most frequent infective agents reasonable for CNS infections in immunocompetent patients as well as their localisation and imaging specifications. MRI scanning is the gold standard to detect inflammatory conditions in the CNS. Imaging can be normal or nonspecifically altered although the infection is culturally or bioptically proven. There are no pathognomonic, pathogen-specific imaging criteria. The localization and dimension of the inflammation depends on the infection pathway. (orig.) [de

  16. Research on the Lift-off Effect of Receiving Longitudinal Mode Guided Waves in Pipes Based on the Villari Effect

    Directory of Open Access Journals (Sweden)

    Jiang Xu

    2016-09-01

    Full Text Available The magnetostrictive guided wave technology as a non-contact measurement can generate and receive guided waves with a large lift-off distance up to tens of millimeters. However, the lift-off distance of the receiving coil would affect the coupling efficiency from the elastic energy to the electromagnetic energy. In the existing magnetomechanical models, the change of the magnetic field in the air gap was ignored since the permeability of the rod is much greater than that of air. The lift-off distance of the receiving coil will not affect the receiving signals based on these models. However, the experimental phenomenon is in contradiction with these models. To solve the contradiction, the lift-off effect of receiving the longitudinal mode guided waves in pipes is investigated based on the Villari effect. A finite element model of receiving longitudinal guided waves in pipes is obtained based on the Villari effect, which takes into account the magnetic field in the pipe wall and the air zone at the same time. The relation between the amplitude of the induced signals and the radius (lift-off distance of the receiving coil is obtained, which is verified by experiment. The coupling efficiency of the receiver is a monotonic decline with the lift-off distance increasing. The decay rate of the low frequency wave is slower than the high frequency wave. Additionally, the results show that the rate of change of the magnetic flux in the air zone and in the pipe wall is the same order of magnitude, but opposite. However, the experimental results show that the error of the model in the large lift-off distance is obvious due to the diffusion of the magnetic field in the air, especially for the high frequency guided waves.

  17. Use of the cylindrically guided wave technique for the inspection of stud bolts, valve stems and pump shafts

    International Nuclear Information System (INIS)

    Light, G.M.; Bloom, E.A.; Ruescher, E.H.; Lui, S.N.

    1989-01-01

    Over the last several years, nuclear power plants have expressed concern about failures of bolting, valve stems, and pump shafts. This paper reports on the development of an ultrasonic technique to inspect these components. The authors have successfully demonstrated the cylindrically guided wave technique (CGWT) on a wide range of stud bolts. The CGWT employs zero-degree longitudinal waves constrained to travel within the boundary of the cylindrically shaped components during inspection. Theoretically explained, mode conversion occurs because the ultrasonic wave is guided down the length of the component. These mode-converted signals are dependent upon the diameter of the component under inspection and the longitudinal- and shear-wave velocities of the component material. This technique has also been successfully used on valve stems in the field. The geometry of the valve stem is very similar to that of the stud bolt

  18. Research on the Lift-off Effect of Receiving Longitudinal Mode Guided Waves in Pipes Based on the Villari Effect

    OpenAIRE

    Xu, Jiang; Sun, Yong; Zhou, Jinhai

    2016-01-01

    The magnetostrictive guided wave technology as a non-contact measurement can generate and receive guided waves with a large lift-off distance up to tens of millimeters. However, the lift-off distance of the receiving coil would affect the coupling efficiency from the elastic energy to the electromagnetic energy. In the existing magnetomechanical models, the change of the magnetic field in the air gap was ignored since the permeability of the rod is much greater than that of air. The lift-off ...

  19. Guided-wave high-performance spectrometers for the MEOS miniature earth observation satellite

    Science.gov (United States)

    Kruzelecky, Roman V.; Wong, Brian; Zou, Jing; Jamroz, Wes; Sloan, James; Cloutis, Edward

    2017-11-01

    The MEOS Miniature Earth Observing Satellite is a low-cost mission being developed for the Canadian Space Agency with international collaborations that will innovatively combine remote correlated atmospheric/land-cover measurements with the corresponding atmospheric and ecosystem modelling in near real-time to obtain simultaneous variations in lower tropospheric GHG mixing ratios and the resulting responses of the surface ecosystems. MEOS will provide lower tropospheric CO2, CH4, CO, N2O, H2O and aerosol mixing ratios over natural sources and sinks using two kinds of synergistic observations; a forward limb measurement and a follow-on nadir measurement over the same geographical tangent point. The measurements will be accomplished using separate limb and nadir suites of innovative miniature line-imaging spectrometers and will be spatially coordinated such that the same air mass is observed in both views within a few minutes. The limb data will consist of 16-pixel vertical spectral line imaging to provide 1-km vertical resolution, while the corresponding nadir measurements will view sixteen 5 by 10 km2 ground pixels with a 160-km East-West swath width. To facilitate the mission accommodation on a low-cost microsat with a net payload mass under 22 kg, groundbreaking miniature guided-wave spectrometers with advanced optical filtering and coding technologies will be employed based on MPBC's patented IOSPEC technologies. The data synergy requirements for each view will be innovatively met using two complementary miniature line-imaging spectrometers to provide broad-band measurements from 1200 to 2450 nm at about 1.2 nm/pixel bandwidth using a multislit binary-coded MEMS-IOSPEC and simultaneous high-resolution multiple microchannels at 0.03 nm FWHM using the revolutionary FP-IOSPEC Fabry-Perot guided-wave spectrometer concept. The guided-wave spectrometer integration provides an order of magnitude reduction in the mass and volume relative to traditional bulk

  20. An Analysis of the Guided Wave Patterns in a Small-bore Titanium Tube by a Magnetostrictive Sensor Technique

    International Nuclear Information System (INIS)

    Cheong, Yong-Moo; Kim, Shin

    2007-01-01

    The presence of damage or defects in pipes or tubes is one of the major problems in nuclear power plants. However, in many cases, it is difficult to inspect all of them by the conventional ultrasonic methods, because of their geometrical complexity and inaccessibility. The magnetostrictive guided wave technique has several advantages for practical applications, such as a 100- percent volumetric coverage of a long segment of a structure, a reduced inspection time and its cost effectiveness, as well as its' relatively simple structure. One promising feature of the magnetostrictive sensor technique is that the wave patterns are relatively clear and simple compared to the conventional piezoelectric ultrasonic transducer. If we can characterize the evolution of the defect signals, it can be a promising tool for a structural health monitoring of pipes for a long period as well as the identification of flaws. An in-bore guided wave probe was developed for an application to small bore heat exchanger tubes. The magnetostrictive probe installed on the hollow cylindrical waveguide generates and detects torsional waves in the waveguide. This waveguide is expanded by the draw bar to create an intimate mechanical contact between the waveguide and the inside surface of the tube being tested. In this paper, we analyzed the wave patterns reflected from various artificial holes in a titanium tube, which is used in the condenser in a nuclear power plant. The torsional guided waves were generated and received by a coil and a DC magnetized nickel strip as well as an inbore guided wave probe. The wave patterns from various defects were compared with two different sensor techniques and a detectable limit of the defected was estimated

  1. Self-action of Bessel wave packets in a system of coupled light guides and formation of light bullets

    Energy Technology Data Exchange (ETDEWEB)

    Balakin, A. A., E-mail: balakin.alexey@yandex.ru; Mironov, V. A.; Skobelev, S. A., E-mail: sk.sa1981@gmail.com [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

    2017-01-15

    The self-action of two-dimensional and three-dimensional Bessel wave packets in a system of coupled light guides is considered using the discrete nonlinear Schrödinger equation. The features of the self-action of such wave fields are related to their initial strong spatial inhomogeneity. The numerical simulation shows that for the field amplitude exceeding a critical value, the development of an instability typical of a medium with the cubic nonlinearity is observed. Various regimes are studied: the self-channeling of a wave beam in one light guide at powers not strongly exceeding a critical value, the formation of the “kaleidoscopic” picture of a wave packet during the propagation of higher-power radiation along a stratified medium, the formation of light bullets during competition between self-focusing and modulation instabilities in the case of three-dimensional wave packets, etc. In the problem of laser pulse shortening, the situation is considered when the wave-field stratification in the transverse direction dominates. This process is accompanied by the self-compression of laser pulses in well enough separated light guides. The efficiency of conversion of the initial Bessel field distribution to two flying parallel light bullets is about 50%.

  2. Laser generated guided waves and finite element modeling for the thickness gauging of thin layers.

    Science.gov (United States)

    Lefevre, F; Jenot, F; Ouaftouh, M; Duquennoy, M; Ourak, M

    2010-03-01

    In this paper, nondestructive testing has been performed on a thin gold layer deposited on a 2 in. silicon wafer. Guided waves were generated and studied using a laser ultrasonic setup and a two-dimensional fast Fourier transform technique was employed to obtain the dispersion curves. A gold layer thickness of 1.33 microm has been determined with a +/-5% margin of error using the shape of the two first propagating modes, assuming for the substrate and the layer an uncertainty on the elastic parameters of +/-2.5%. A finite element model has been implemented to validate the data post-treatment and the experimental results. A good agreement between the numerical simulation, the analytical modeling and the experimentations has been observed. This method was considered suitable for thickness layer higher than 0.7 microm.

  3. Parametric study of guided ultrasonic wave propagation in carbon-fiber composite plates

    Science.gov (United States)

    Ibrahim, N. A.; Kamarudin, M. A.; Jurimi, M. H. F. M.; Murat, B. I. S.

    2018-03-01

    The aim of this work is to study the guided ultrasonic wave (GUW) behaviour in composite plates using 3D Finite Element Analysis (FEA). Two types of composite models are chosen: plates with and without damage. The damage is modelled as a circular-shaped delamination inside the plate, representing one kind of low-velocity impact damage. Parameters such as excitation frequency, monitoring directivity, plate thickness, delamination size and shape were used to investigate the influence of these parameters on the GUW propagation and scattering behaviour. The models were constructed and coded in Matlab platform, while the simulations were performed in ABAQUS Explicit. From the results, the received signals have shown a strong dependency on the parameters. Significant scattering from the models with delamination were also observed, which indicates the possibility of using GUW for rapid non-destructive monitoring of composite panels and structures.

  4. Near-to-eye electroholography via guided-wave acousto-optics for augmented reality

    Science.gov (United States)

    Jolly, Sundeep; Savidis, Nickolaos; Datta, Bianca; Smalley, Daniel; Bove, V. Michael

    2017-03-01

    Near-to-eye holographic displays act to directly project wavefronts into a viewer's eye in order to recreate 3-D scenes for augmented or virtual reality applications. Recently, several solutions for near-to-eye electroholography have been proposed based on digital spatial light modulators in conjunction with supporting optics, such as holographic waveguides for light delivery; however, such schemes are limited by the inherent low space-bandwidth product available with current digital SLMs. In this paper, we depict a fully monolithic, integrated optical platform for transparent near-to-eye holographic display requiring no supporting optics. Our solution employs a guided-wave acousto-optic spatial light modulator implemented in lithium niobate in conjunction with an integrated Bragg-regime reflection volume hologram.

  5. Quantitative Evaluation of Defect Based on Ultrasonic Guided Wave and CHMM

    Directory of Open Access Journals (Sweden)

    Chen Le

    2016-01-01

    Full Text Available The axial length of pipe defects is not linear with the reflection coefficient, which is difficult to identify the axial length of the defect by the reflection coefficient method. Continuous Hidden Markov Model (CHMM is proposed to accurately classify the axial length of defects, achieving the objective of preliminary quantitative evaluation. Firstly, wavelet packet decomposition method is used to extract the characteristic information of the guided wave signal, and Kernel Sliced Inverse Regression (KSIR method is used to reduce the dimension of feature set. Then, a variety of CHMM models are trained for classification. Finally, the trained models are used to identify the artificial corrosion defects on the outer surface of the pipe. The results show that the CHMM model has better robustness and can accurately identify the axial defects.

  6. Application of empowerment theory for CNS practice.

    Science.gov (United States)

    Carlson-Catalano, J M

    1993-11-01

    Power is necessary for the clinical nurse specialist (CNS) to successfully conduct objectives of practice in bureaucratic hospital settings. To obtain power, the CNS could use strategies of an empowerment theory to fully operationalize roles in hospitals. This article will discuss how the CNS may be empowered utilizing strategies in four empowering categories. In addition, the many benefits of empowering the CNS are reviewed.

  7. Monitoring the reflection from an artificial defect in rail track using guided wave ultrasound

    Science.gov (United States)

    Loveday, Philip W.; Taylor, Rebecca M. C.; Long, Craig S.; Ramatlo, Dineo A.

    2018-04-01

    Guided wave ultrasound has the potential to detect relatively large defects in continuously welded rail track at long range. As monitoring can be performed in near real time it would be acceptable to only detect fairly large cracks provided this is achieved prior to complete rail breakage. Heavy haul rail lines are inspected periodically by conventional ultrasound and sections with even relatively small cracks are removed; therefore, no sizable defects are available to demonstrate monitoring in the presence of realistic environmental operating conditions. Instead, we glued a small mass to the rail to simulate reflection from a crack and monitored the guided wave signals as the glue joint deteriorated over time. Data was collected over a two week period on an operational heavy haul line. A piezoelectric transducer mounted under the head of the rail was used in pulse-echo mode to transmit and receive a mode of propagation with energy confined mainly in the head of the rail. The small mass was attached under the head of the rail, at a distance of 375m from the transducer, using a cyanoacrylate glue, which was not expected to remain intact for long. Pre-processing of the collected signals involved rejection of signals containing train noise, averaging, filtering and dispersion compensation. Reflections from aluminothermic welds were used to stretch and scale the signals to reduce the influence of temperature variations. Singular value decomposition and independent component analysis were then applied to the signals with the aim of separating the reflection caused by the artificial defect from the background signal. The performance of these techniques was compared for different time spans. The reflection from the artificial defect showed unanticipated fluctuations.

  8. Rapid, long range inspection of chemical plant pipework using guided waves

    International Nuclear Information System (INIS)

    Alleynel, D.N.; Pavlakovicl, B.; Lowel, M.J.S.; Cawley, P.

    2002-01-01

    Corrosion in pipe work is a major problem in the oil, chemical and other industries. Many pipes are insulated which means that even external corrosion cannot be seen without removing the insulation, which is prohibitively expensive. Particularly severe problems are encountered at road crossings where the pipe cannot be inspected without excavation. Ultrasonic guided waves in the pipe wall provide an attractive solution to this problem because they can be excited at one location on the pipe and will propagate many meters along the pipe returning echoes indicating the presence of corrosion or other pipe features. The technique has now been commercialized and this paper describes the results of an extensive set of field trials using the method, together with the results of systematic laboratory and theoretical investigations of the influence of defect depth and circumferential extent on the guided wave reflectivity. It is shown that propagation distances of over 25 meters in pipe diameters from 2 to 24 inch can be obtained using a dry coupled piezoelectric transducer system. The defect detection sensitivity is generally set to the removal of 10% of the cross-sectional area of the pipe at a single location, but it is often possible to find smaller defects if required. This technique was originally designed to work on pipes that were either uncoated or covered with, for example, epoxy paint. Recent tests have shown promising results with more attenuative coatings and these are discussed. The results show that the technique has wide application in pipe systems in the chemical and other industries. (author)

  9. Beam pattern improvement by compensating array nonuniformities in a guided wave phased array

    International Nuclear Information System (INIS)

    Kwon, Hyu-Sang; Lee, Seung-Seok; Kim, Jin-Yeon

    2013-01-01

    This paper presents a simple data processing algorithm which can improve the performance of a uniform circular array based on guided wave transducers. The algorithm, being intended to be used with the delay-and-sum beamformer, effectively eliminates the effects of nonuniformities that can significantly degrade the beam pattern. Nonuniformities can arise intrinsically from the array geometry when the circular array is transformed to a linear array for beam steering and extrinsically from unequal conditions of transducers such as element-to-element variations of sensitivity and directivity. The effects of nonuniformities are compensated by appropriately imposing weight factors on the elements in the projected linear array. Different cases are simulated, where the improvements of the beam pattern, especially the level of the highest sidelobe, are clearly seen, and related issues are discussed. An experiment is performed which uses A0 mode Lamb waves in a steel plate, to demonstrate the usefulness of the proposed method. The discrepancy between theoretical and experimental beam patterns is explained by accounting for near-field effects. (paper)

  10. Guided wave propagation and scattering in pipeworks comprising elbows: Theoretical and experimental results

    International Nuclear Information System (INIS)

    Bakkali, M El; Lhémery, A; Baronian, V; Chapuis, B

    2015-01-01

    Elastic guided waves (GW) are used to inspect pipeworks in various industries. Modelling tools for simulating GW inspection are necessary to understand complex scattering phenomena occurring at specific features (welds, elbows, junctions...). In pipeworks, straight pipes coexist with elbows. GW propagation in the former cases is well-known, but is less documented in the latter. Their scattering at junction of straight and curved pipes constitutes a complex phenomenon. When a curved part is joined to two straight parts, these phenomena couple and give rise to even more complex wave structures. In a previous work, the SemiAnalytic Finite Element method extended to curvilinear coordinates was used to handle GW propagation in elbows, combined with a mode matching method to predict their scattering at the junction with a straight pipe. Here, a pipework comprising an arbitrary number of elbows of finite length and of different curvature linking straight pipes is considered. A modal scattering matrix is built by cascading local scattering and propagation matrices. The overall formulation only requires meshing the pipe section to compute both the modal solutions and the integrals resulting from the mode-matching method for computing local scattering matrices. Numerical predictions using this approach are studied and compared to experiments

  11. Warped frequency transform analysis of ultrasonic guided waves in long bones

    Science.gov (United States)

    De Marchi, L.; Baravelli, E.; Xu, K.; Ta, D.; Speciale, N.; Marzani, A.; Viola, E.

    2010-03-01

    Long bones can be seen as irregular hollow tubes, in which, for a given excitation frequency, many ultrasonic Guided Waves (GWs) can propagate. The analysis of GWs is potential to reflect more information on both geometry and material properties of the bone than any other method (such as dual-energy X-ray absorptiometry, or quantitative computed tomography), and can be used in the assessment of osteoporosis and in the evaluation of fracture healing. In this study, time frequency representations (TFRs) were used to gain insights into the expected behavior of GWs in bones. To this aim, we implemented a dedicated Warped Frequency Transform (WFT) which decomposes the spectrotemporal components of the different propagating modes by selecting an appropriate warping map to reshape the frequency axis. The map can be designed once the GWs group velocity dispersion curves can be predicted. To this purpose, the bone is considered as a hollow cylinder with inner and outer diameter of 16.6 and 24.7 mm, respectively, and linear poroelastic material properties in agreement with the low level of stresses induced by the waves. Timetransient events obtained experimentally, via a piezoelectric ultrasonic set-up applied to bovine tibiae, are analyzed. The results show that WFT limits interference patterns which appear with others TFRs (such as scalograms or warpograms) and produces a sparse representation suitable for characterization purposes. In particular, the mode-frequency combinations propagating with minimal losses are identified.

  12. Experimental Verification of Guided-Wave Lumped Circuits Using Waveguide Metamaterials

    Science.gov (United States)

    Li, Yue; Zhang, Zhijun

    2018-04-01

    Through the construction and characterization in microwave frequencies, we experimentally demonstrate our recently developed theory of waveguide lumped circuits, i.e., waveguide metatronics [Sci. Adv. 2, e1501790 (2016), 10.1126/sciadv.1501790], as a method to design subwavelength-scaled analog circuits. In the paradigm of waveguide metatronics, numbers of lumped inductors and capacitors are easily integrated functionally inside the waveguide, which is an irreplaceable transmission line in millimeter-wave and terahertz systems with the advantages of low radiation loss and low crosstalk. An example of multiple-ordered metatronic filters with layered structures is fabricated utilizing the technique of substrate integrated waveguides, which can be easily constructed by the printed-circuit-board process. The materials used in the construction are also typical microwave materials with positive permittivity, low loss, and negligible dispersion, imitating the plasmonic materials with negative permittivity in the optical domain. The results verify the theory of waveguide metatronics, which provides an efficient platform of functional lumped circuit design for guided-wave processing.

  13. Waves and Particles, The Orbital Atom, Parts One and Two of an Integrated Science Sequence, Teacher's Guide, 1973 Edition.

    Science.gov (United States)

    Portland Project Committee, OR.

    This teacher's guide includes parts one and two of the four-part third year Portland Project, a three-year integrated secondary science curriculum sequence. The Harvard Project Physics textbook is used for reading assignments for part one. Assignments relate to waves, light, electricity, magnetic fields, Faraday and the electrical age,…

  14. The Effect of General Corrosion on the Guided Wave Inspection of the Pipeline

    Directory of Open Access Journals (Sweden)

    Zhang Jin Heng

    2016-01-01

    Full Text Available The guided wave method can inspect pipelines very quickly and widely. For instance, it can inspect the overall pipelines by digging several detection pits or removing part of coating material to set the array ring. However, it will make the guided wave attenuate more seriously and make the signals hard to identify when setting the array ring on the general corrosion. In this study, the wave propagation will be discussed when the general corrosion is under the array ring and the severe localized corrosion is inside the general corrosion via experiment and finite element method. The results showed that the excitation energy will be lower when the array ring set on the pipe surface with the general corrosion. By two-dimensional Fourier transform analysis, its non-uniform contact surface will increase asymmetric modal and mix signals. The energy attenuation will increase when the corrosion depth is deepened or the inspection frequency is risen. For example, the 2 mm deep general corrosion will attenuate −1.09 dB/m at 20 kHz and attenuate −3.01 dB/m at 40 kHz; the 4 mm deep general corrosion will attenuation −5.76 dB/m at 20 kHz and attenuation −23.19 dB/m at 40 kHz. However, the coherent signals which were caused by the general corrosion will decay with increasing frequency. For example, the coherent signals of 2 mm deep general corrosion are −23.67 dB at 20 kHz and −35.44 dB at 40 kHz; then, the 20 mm long and 3.5 mm deep localized corrosion which signal is −26.34 dB at 20 kHz and −26.94 dB at 40 kHz will be detected easily at high frequency. It can provide detectors to understand the impact when the array ring set on the area of general corrosion and the way to distinguish the localized corrosion which is inside the area of general corrosion.

  15. Constraining the hydration of the subducting Nazca plate beneath Northern Chile using subduction zone guided waves

    Science.gov (United States)

    Garth, Tom; Rietbrock, Andreas

    2017-09-01

    Guided wave dispersion is observed from earthquakes at 180-280 km depth recorded at stations in the fore-arc of Northern Chile, where the 44 Ma Nazca plate subducts beneath South America. Characteristic P-wave dispersion is observed at several stations in the Chilean fore-arc with high frequency energy (>5 Hz) arriving up to 3 s after low frequency (accounted for if dipping low velocity fault zones are included within the subducting lithospheric mantle. A grid search over possible LVL and faults zone parameters (width, velocity contrast and separation distance) was carried out to constrain the best fitting model parameters. Our results imply that fault zone structures of 0.5-1.0 km thickness, and 5-10 km spacing, consistent with observations at the outer rise are present within the subducted slab at intermediate depths. We propose that these low velocity fault zone structures represent the hydrated structure within the lithospheric mantle. They may be formed initially by normal faults at the outer rise, which act as a pathway for fluids to penetrate the deeper slab due to the bending and unbending stresses within the subducting plate. Our observations suggest that the lithospheric mantle is 5-15% serpentinised, and therefore may transport approximately 13-42 Tg/Myr of water per meter of arc. The guided wave observations also suggest that a thin LVL (∼1 km thick) interpreted as un-eclogitised subducted oceanic crust persists to depths of at least 220 km. Comparison of the inferred seismic velocities with those predicted for various MORB assemblages suggest that this thin LVL may be accounted for by low velocity lawsonite-bearing assemblages, suggesting that some mineral-bound water within the oceanic crust may be transported well beyond the volcanic arc. While older subducting slabs may carry more water per metre of arc, approximately one third of the oceanic material subducted globally is of a similar age to the Nazca plate. This suggests that subducting oceanic

  16. The application of low frequency longitudinal guided wave mode for the inspection of multi-hole steel floral pipes

    International Nuclear Information System (INIS)

    Liu, Z H; Xie, X D; Wu, B; Li, Y H; He, C F

    2012-01-01

    Shed-pipe grouting technology, an effective advanced supporting method, is often used in the excavation of soft strata. Steel floral pipes are one of the key load-carrying components of shed-pipe grouting supporting structures. Guided waves are a very attractive methodology to inspect multi-hole steel floral pipes as they offer long range inspection capability, mode and frequency tuning, and cost effectiveness. In this contribution, preliminary experiments are described for the inspection of steel floral pipes using a low frequency longitudinal guided wave mode, L(0,2). The relation between the number of grouting holes and the peak-to-peak amplitude of the first end-reflected signal was obtained. The effect of the grouting holes in steel floral pipes on the propagation velocity of the L(0,2) mode at 30 kHz was analyzed. Experimental results indicate that the typical grouting holes in steel floral pipe have no significant effect on the propagation of this mode. As a result, low frequency longitudinal guided wave modes have potential for the non-destructive long range inspection of multi-hole steel floral pipes. Furthermore, the propagation velocity of the investigated L(0,2) mode at 30 kHz decreases linearly with the increase of the number of grouting holes in a steel floral pipe. It is also noticeable that the effect of the grouting holes cumulates along with the increase in the number of grouting holes and subsequent increase in reflection times of longitudinal guided waves in the steel floral pipe. The application potential of the low frequency longitudinal guided wave technique for the inspection of embedded steel floral pipes is discussed.

  17. Innate Interferons Regulate CNS Inflammation

    DEFF Research Database (Denmark)

    Dieu, Ruthe; Khorooshi, Reza M. H.; Mariboe, Anne

    Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) whose pathology is characterised by demyelination and axonal damage. This results from interplay between CNS-resident glia, infiltrating leukocytes and a plethora of cytokines and chemokines. Currently...... potential IFN-inducing receptor that signals through NF-kB. Receptor activator of NF-kB (RANK) belongs to the TNF-receptor superfamily and has been shown to induce IFN-beta in medullary thymic epithelial cells affecting autoimmune regulatory processes and osteoclast precursor cells in association to bone...

  18. Guided wave technology for in-service inspection and online monitoring for long term operation of nuclear power plants

    International Nuclear Information System (INIS)

    Bertoncini, Francesco; Raugi, Marco; Cappelli, Mauro; Cordella, Francesco; Mazzini, Davide

    2015-01-01

    In-Service Inspection (ISI) and monitoring of all equipment (Systems, Structures and Components, SSCs) of a Nuclear Power Plant (NPP), are actions aimed at preventing failures both for economical and safety purposes. SSCs ageing due to stresses such as corrosion, load variations, flow conditions, temperature and neutron irradiation can be a potential limit for NPP life extension or operation beyond their license term (Long Term Operation. LTO). ISI has a main role on the actual possibility of LTO assuring the required safety. Guided Waves are structure-borne ultrasonic waves that propagate along the structure confined and guided by its geometric boundaries. Guided Wave Testing can find defect locations through long-range screening using low-frequency waves (from 5 to 250 kHz). The technology is regularly used for pipe testing in the oil and gas industry. In the nuclear industry, regulators are working to standardize monitoring and inspection procedures. To use the technology inside an active plant, operators must solve issues like high temperatures (up to more than 300degC inside a light-water reactor's primary piping), high wall thickness of components in the primary circuit and characteristic defect typologies. Magnetostrictive sensors are expected to overcome such issues due to their physical properties, namely robust constitution and simplicity. Recent experimental results have demonstrated magnetostrictive transducers can withstand temperatures close to 300degC. In this paper, new experimental tests conducted using such a methodology will be described and open issues related to high temperature guided wave applications (e.g. wave velocity or amplitude fluctuations during propagation in variable temperature components) will be discussed. (author)

  19. Crack-depth effects in the cylindrically guided wave technique for bolt and pump-shaft inspections

    International Nuclear Information System (INIS)

    Tsai, Y.M.; Liu, S.N.; Light, G.M.

    1991-01-01

    Nuclear power plants have experienced the failures of bolts and pump shafts. The industry is concerned about nondestructive evaluation (NDE) techniques that can be applied to these components. The cylindrically guided wave technique (CGWT) has been developed to detect the simulated circumferential defects in long bolts and studs. The ultrasonic CGWT employs the zero-degree longitudinal waves constrained to travel within the boundary of the components with cylindrical shape during inspection. When longitudinal waves are guided to travel along a cylinder, and impinge onto a circumferential defect, the waves are scattered at the crack on the cylinder surface. In this work, the wave scattering at the circumferential crack on a long cylinder is investigated. The transfer factor of the scattered waves is calculated for a wide range of frequency spectra. The scattered waveform at a distance away from a crack is calculated. The effect that crack depth exerts to the waveform in CGWT is shown. CGWT signals, waveform calculation and so on are reported. (K.I.)

  20. Structural Diagnostics of CFRP Composite Aircraft Components by Ultrasonic Guided Waves and Built-In Piezoelectric Transducers

    Energy Technology Data Exchange (ETDEWEB)

    Matt, Howard M. [Univ. of California, San Diego, CA (United States)

    2006-01-01

    To monitor in-flight damage and reduce life-cycle costs associated with CFRP composite aircraft, an autonomous built-in structural health monitoring (SHM) system is preferred over conventional maintenance routines and schedules. This thesis investigates the use of ultrasonic guided waves and piezoelectric transducers for the identification and localization of damage/defects occurring within critical components of CFRP composite aircraft wings, mainly the wing skin-to-spar joints. The guided wave approach for structural diagnostics was demonstrated by the dual application of active and passive monitoring techniques. For active interrogation, the guided wave propagation problem was initially studied numerically by a semi-analytical finite element method, which accounts for viscoelastic damping, in order to identify ideal mode-frequency combinations sensitive to damage occurring within CFRP bonded joints. Active guided wave tests across three representative wing skin-to-spar joints at ambient temperature were then conducted using attached Macro Fiber Composite (MFC) transducers. Results from these experiments demonstrate the importance of intelligent feature extraction for improving the sensitivity to damage. To address the widely neglected effects of temperature on guided wave base damage identification, analytical and experimental analyses were performed to characterize the influence of temperature on guided wave signal features. In addition, statistically-robust detection of simulated damage in a CFRP bonded joint was successfully achieved under changing temperature conditions through a dimensionally-low, multivariate statistical outlier analysis. The response of piezoceramic patches and MFC transducers to ultrasonic Rayleigh and Lamb wave fields was analytically derived and experimentally validated. This theory is useful for designing sensors which possess optimal sensitivity toward a given mode-frequency combination or for predicting the frequency dependent

  1. Genetic models for CNS inflammation

    DEFF Research Database (Denmark)

    Owens, T; Wekerle, H; Antel, J

    2001-01-01

    The use of transgenic technology to over-express or prevent expression of genes encoding molecules related to inflammation has allowed direct examination of their role in experimental disease. This article reviews transgenic and knockout models of CNS demyelinating disease, focusing primarily on ...

  2. Basic Concepts of CNS Development.

    Science.gov (United States)

    Nowakowski, R. S.

    1987-01-01

    The goals of this review are to: (1) provide a set of concepts to aid in the understanding of complex processes which occur during central nervous system (CNS) development; (2) illustrate how they contribute to our knowlege of adult brain anatomy; and (3) delineate how modifications of normal developmental processes may affect the structure and…

  3. CNS complications of rotavirus gastroenteritis

    International Nuclear Information System (INIS)

    Volosinova, D.

    2010-01-01

    Rotavirus infection may be accompanied by serious complications, e.g. disabilities central nervous system (CNS). Theory rotavirus penetration across the blood-brain barrier and subsequent rota-associated convulsions by the 2-year case-history of the patient. Rotavirosis minor gastrointestinal symptoms may lead to erroneous diagnosis. (author)

  4. Modeling of second-harmonic generation of circumferential guided wave propagation in a composite circular tube

    Science.gov (United States)

    Li, Mingliang; Deng, Mingxi; Gao, Guangjian; Xiang, Yanxun

    2018-05-01

    This paper investigated modeling of second-harmonic generation (SHG) of circumferential guided wave (CGW) propagation in a composite circular tube, and then analyzed the influences of interfacial properties on the SHG effect of primary CGW. Here the effect of SHG of primary CGW propagation is treated as a second-order perturbation to its linear wave response. Due to the convective nonlinearity and the inherent elastic nonlinearity of material, there are second-order bulk driving forces and surface/interface driving stresses in the interior and at the surface/interface of a composite circular tube, when a primary CGW mode propagates along its circumference. Based on the approach of modal expansion analysis for waveguide excitation, the said second-order driving forces/stresses are regarded as the excitation sources to generate a series of double-frequency CGW modes that constitute the second-harmonic field of the primary CGW propagation. It is found that the modal expansion coefficient of each double-frequency CGW mode is closely related to the interfacial stiffness constants that are used to describe the interfacial properties between the inner and outer circular parts of the composite tube. Furthermore, changes in the interfacial stiffness constants essentially influence the dispersion relation of CGW propagation. This will remarkably affect the efficiency of cumulative SHG of primary CGW propagation. Some finite element simulations have been implemented of response characteristics of cumulative SHG to the interfacial properties. Both the theoretical analyses and numerical simulations indicate that the effect of cumulative SHG is found to be much more sensitive to changes in the interfacial properties than primary CGW propagation. The potential of using the effect of cumulative SHG by primary CGW propagation to characterize a minor change in the interfacial properties is considered.

  5. Modal content based damage indicators and phased array transducers for structural health monitoring of aircraft structures using ultrasonic guided waves

    Science.gov (United States)

    Ren, Baiyang

    Composite materials, especially carbon fiber reinforced polymers (CFRP), have been widely used in the aircraft industry because of their high specific strength and stiffness, resistance to corrosion and good fatigue life. Due to their highly anisotropic material properties and laminated structures, joining methods like bolting and riveting are no longer appropriate for joining CFRP since they initiate defects during the assembly and severely compromise the integrity of the structure; thus new techniques for joining CFRP are highly demanded. Adhesive bonding is a promising method because it relieves stress concentration, reduces weight and provides smooth surfaces. Additionally, it is a low-cost alternative to the co-cured method which is currently used to manufacture components of aircraft fuselage. Adhesive defects, disbonds at the interface between adherend and adhesive layer, are focused on in this thesis because they can be initialized by either poor surface preparation during the manufacturing or fatigue loads during service. Aircraft need structural health monitoring (SHM) systems to increase safety and reduce loss, and adhesive bonds usually represent the hotspots of the assembled structure. There are many nondestructive evaluation (NDE) methods for bond inspection. However, these methods cannot be readily integrated into an SHM system because of the bulk size and weight of the equipment and requirement of accessibility to one side of the bonded joint. The first objective of this work is to develop instruments, actuators, sensors and a data acquisition system for SHM of bond lines using ultrasonic guided waves which are well known to be able to cover large volume of the structure and inaccessible regions. Different from widely used guided wave sensors like PZT disks, the new actuators, piezoelectric fiber composite (PFC) phased array transducers0 (PAT), can control the modal content of the excited waves and the new sensors, polyvinylidene fluoride (PVDF

  6. Cylindrically guided wave technique for detection of stress corrosion cracking and corrosion wastage in long stud-bolts

    International Nuclear Information System (INIS)

    Light, G.M.; Joshi, N.R.

    1986-01-01

    The authors discuss how, when performing an ultrasonic inspection of a cylindrical body, the sound waves, or pulses, will interact with the boundaries of the cylinder and produce mode-converted as well as normal longitudinal waves. The elastic energy of the wave propagating along the length of the cylinder is concentrated and produces strong echoes from shallow defects in the specimen. In threaded specimens, the guided wave produces signals from the threads that can be differentiated from defects in the cylinder. This paper reports on a study using the guided wave theory conducted to determine the optimum inspection transducer size and frequency relative to stud-bolt diameter and length. Bolts ranging from 25 to 285 cm (10 to 112 in.) in length and 2.5 to 11.5 cm (1 to 4.5 in.) in diameter were tested. For all cases, theoretical predictions agreed well with the experimental data. In this paper, the theory, experimental apparatus, and testing results are discussed

  7. Nuclear Containment Inspection Using AN Array of Guided Wave Sensors for Damage Localization

    Science.gov (United States)

    Cobb, A. C.; Fisher, J. L.

    2010-02-01

    Nuclear power plant containments are typically both the last line of defense against the release of radioactivity to the environment and the first line of defense to protect against intrusion from external objects. As such, it is important to be able to locate any damage that would limit the integrity of the containment itself. Typically, a portion of the containment consists of a metallic pressure boundary that encloses the reactor primary circuit. It is made of thick steel plates welded together, lined with concrete and partially buried, limiting areas that can be visually inspected for corrosion damage. This study presents a strategy using low frequency (<50 kHz) guided waves to find corrosion-like damage several meters from the probe in a mock-up of the containment vessel. A magnetostrictive sensor (MsS) is scanned across the width of the vessel, acquiring waveforms at a fixed interval. A beam forming strategy is used to localize the defects. Experimental results are presented for a variety of damage configurations, demonstrating the efficacy of this technique for detecting damage smaller than the ultrasonic wavelength.

  8. Microwave pre-heating of natural rubber using a rectangular wave guide (MODE: TE10

    Directory of Open Access Journals (Sweden)

    Doo-ngam, N.

    2007-11-01

    Full Text Available This paper presents an application of microwave radiation for pre-heating of natural rubbercompounding with various sulphur contents. The natural rubber-compounding was pre-heated by microwave radiation using a rectangular wave guide system (MODE: TE10 operating at frequency of 2.45 GHz in which the power can vary from 0 to 1500 W. In the present work, the influence of power input, sample thickness, and sulphur content were examined after applying microwave radiation to the rubber samples. Results are discussed regarding the thermal properties, 3-D network, dielectric properties and chemical structures. From the result, firstly, it was found that microwave radiation can be applied to pre-heating natural rubber-compounding before the vulcanization process. Secondly, microwave radiation was very useful for pre-heating natural rubber-compounding that has a thickness greater than 5mm. Thirdly, crosslinking in natural rubber-compounding may occurs after pre-heating by microwave radiation though Fourier Transform Infrared Spectroscopy(FTIR. Finally, there a little effect of sulphur content on temperature profiles after applying microwave radiation to the natural rubber-compounding. Moreover, natural rubber-compounding without carbon black showed a lower heat absorption compared with natural rubbercompounding filled carbon black. This is due to the difference in dielectric loss factor. This preliminary result will be useful information in terms of microwave radiation for pre-heating natural rubber-compounding and rubber processing in industry.

  9. Application of the cylindrically guided wave technique for bolt and pump-shaft inspections

    International Nuclear Information System (INIS)

    Light, G.M.; Ruescher, E.H.; Bloom, E.A.; Tsai, Y.M.

    1990-01-01

    Southwest Research Institute (SwRI) has been working with the cylindrically guided wave technique (CGWT) since late 1982. The initial work was aimed at inspecting reactor pressure vessel hold-down studs. The CGWT was shown to be able to detect defects as small as 0.060 inch (1.5 mm) deep through metal paths up to 120 inches (304 cm) in stud bolt carbon steel. Later developments in the application of CGWT were aimed at inspecting reactor coolant pump (RCP) shafts. The RCP shafts are usually approximately 2 meters long and have changing diameters along the length, from approximately 12 cm to 23 cm in discrete steps. The pump shafts have been susceptible to small cracks and can be inspected most cost-effectively from the top of the shaft. A matrix transducer composed of six 1-inch (2.54-cm) diameter transducers along with pulsing and receiving electronics (EPRI Pump-Shaft Inspection System) was developed during 1988. A patent application for this technology has been made. This report describes the work conducted during 1989 and the results obtained

  10. Evaluation of weld defects in stainless steel 316L pipe using guided wave

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joon Hyun [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of); Lee, Jin Kyung [Dept. of Mechanical Engineering, Dongeui University, Busan (Korea, Republic of)

    2015-02-15

    Stainless steel is a popular structural materials for liquid-hydrogen storage containers and piping components for transporting high-temperature fluids because of its superior material properties such as high strength and high corrosion resistance at elevated temperatures. In general, tungsten inert gas (TIG) arc welding is used for bonding stainless steel. However, it is often reported that the thermal fatigue cracks or initial defects in stainless steel after welding decreases the reliability of the material. The objective of this paper is to clarify the characteristics of ultrasonic guided wave propagation in relation to a change in the initial crack length in the welding zone of stainless steel. For this purpose, three specimens with different artificial defects of 5 mm, 10 mm, and 20 mm in stainless steel welds were prepared. By considering the thickness of s stainless steel pipe, special attention was given to both the L(0,1) mode and L(0,2) mode in this study. It was clearly found that the L(0,2) mode was more sensitive to defects than the L(0,1) mode. Based on the results of the L(0,1) and L(0,2) mode analyses, the magnitude ratio of the two modes was more effective than studying each mode when evaluating defects near the welded zone of stainless steel because of its linear relationship with the length of the artificial defect.

  11. A case study of application of guided waves for detecting corrosion in pipelines

    Science.gov (United States)

    Rostami, Javad; Safizadeh, Mir Saeed

    2012-05-01

    Every year noticeable amount of money is spent on fixing and replacing the damaged pipes which carry gas and fuel. Since there is a possibility for a catastrophic failure, knowing the proper time of this repair is of great importance. Because significant proportion of failures is due to wall thinning of pipes because of the corrosion, detecting the wall thinning has been a main part of nondestructive testing of pipes. There are wide variety of NDT techniques to detect this kind of defect such as conventional ultrasonic, eddy current, radiography etc. but some of these techniques, for example conventional ultrasonic needs the insulation of pipes removed and in some other cases such as radiography the test is not done at a reasonable speed. A new method of nondestructive testing of pipes which has the potential to test a long distance in a short period of time and does not need the whole insulation removed, has drawn a lot of attention. In this paper, the ability of ultrasonic guided waves for detecting corrosion in gas pipelines is experimentally investigated.

  12. Guided waves dispersion equations for orthotropic multilayered pipes solved using standard finite elements code.

    Science.gov (United States)

    Predoi, Mihai Valentin

    2014-09-01

    The dispersion curves for hollow multilayered cylinders are prerequisites in any practical guided waves application on such structures. The equations for homogeneous isotropic materials have been established more than 120 years ago. The difficulties in finding numerical solutions to analytic expressions remain considerable, especially if the materials are orthotropic visco-elastic as in the composites used for pipes in the last decades. Among other numerical techniques, the semi-analytical finite elements method has proven its capability of solving this problem. Two possibilities exist to model a finite elements eigenvalue problem: a two-dimensional cross-section model of the pipe or a radial segment model, intersecting the layers between the inner and the outer radius of the pipe. The last possibility is here adopted and distinct differential problems are deduced for longitudinal L(0,n), torsional T(0,n) and flexural F(m,n) modes. Eigenvalue problems are deduced for the three modes classes, offering explicit forms of each coefficient for the matrices used in an available general purpose finite elements code. Comparisons with existing solutions for pipes filled with non-linear viscoelastic fluid or visco-elastic coatings as well as for a fully orthotropic hollow cylinder are all proving the reliability and ease of use of this method. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Formation of ECR Plasma in a Dielectric Plasma Guide under Self-Excitation of a Standing Ion-Acoustic Wave

    Science.gov (United States)

    Balmashnov, A. A.; Kalashnikov, A. V.; Kalashnikov, V. V.; Stepina, S. P.; Umnov, A. M.

    2018-01-01

    The formation of a spatially localized plasma with a high brightness has been experimentally observed in a dielectric plasma guide under the electron cyclotron resonance discharge at the excitation of a standing ion-acoustic wave. The results obtained show the possibility of designing compact high-intensity radiation sources with a spectrum determined by the working gas or gas mixture type, high-intensity chemically active particle flow sources, and plasma thrusters for correcting orbits of light spacecraft.

  14. Estimation of seismic velocity in the subducting crust of the Pacific slab beneath Hokkaido, northern Japan by using guided waves

    Science.gov (United States)

    Shiina, T.; Nakajima, J.; Toyokuni, G.; Kita, S.; Matsuzawa, T.

    2014-12-01

    A subducting crust contains a large amount of water as a form of hydrous minerals (e.g., Hacker et al., 2003), and the crust plays important roles for water transportation and seismogenesis in subduction zones at intermediate depths (e.g., Kirby et al., 1996; Iwamori, 2007). Therefore, the investigation of seismic structure in the crust is important to understand ongoing physical processes with subduction of oceanic lithosphere. A guided wave which propagates in the subducting crust is recorded in seismograms at Hokkaido, northern Japan (Shiina et al., 2014). Here, we estimated P- and S-wave velocity in the crust with guided waves, and obtained P-wave velocity of 6.6-7.3 km/s and S-wave velocity of 3.6-4.2 km/s at depths of 50-90 km. Moreover, Vp/Vs ratio in the crust is calculated to be 1.80-1.85 in that depth range. The obtained P-wave velocity about 6.6km/s at depths of 50-70 km is consistent with those estimated in Tohoku, northeast Japan (Shiina et al., 2013), and this the P-wave velocity is lower than those expected from models of subducting crustal compositions, such as metamorphosed MORB model (Hacker et al., 2003). In contrast, at greater depths (>80 km), the P-wave velocity marks higher velocity than the case of NE Japan and the velocity is roughly comparable to those of the MORB model. The obtained S-wave velocity distribution also shows characteristics similar to P waves. This regional variation may be caused by a small variation in thermal regime of the Pacific slab beneath the two regions as a result of the normal subduction in Tohoku and oblique subduction in Hokkaido. In addition, the effect of seismic anisotropy in the subducting crust would not be ruled out because rays used in the analysis in Hokkaido propagate mostly in the trench-parallel direction, while those in Tohoku are sufficiently criss-crossed.

  15. Coupling of modal and finite elements methods for the diffraction of guided elastics waves: application to non destructive testing

    International Nuclear Information System (INIS)

    Baronian, V.

    2009-11-01

    A typical nondestructive examination based on guided elastic waves can be simulated by considering an elastic 2D (a plate) or 3D (a rod) guide that contains a defect (a crack, a local heterogeneity due to a weld etc.). Our aim is to solve numerically the problem of the scattering by a defect of a mode propagating in a guide. This has been achieved by developing a method that couples i) finite elements in the smallest possible region of the guide that contains the defect, with ii) the modal decomposition of waves outside this region. The main challenge consists in finding the right linking condition of both representations. A decisive tool is the obtaining of an orthogonality relation which makes it possible to project the finite element solution onto guided modes. For this, the problem is formulated in terms of hybrid vectors (displacement/stress) for which a bi-orthogonality relation exists, namely, the Fraser's relation. It is then possible to derive an exact (transparent) condition on the artificial boundaries of the finite element domain; the modal series taken into account being necessarily truncated, transparency is achieved only approximately. Eventually, this boundary condition is integrated in a variational approach (in terms of displacement) in order to develop a finite element method. The transparent boundary condition being expressed in terms of the hybrid vectors, the stress normal to the artificial boundary is introduced as a supplementary unknown, together with a mixed formulation. Both 2D and 3D isotropic guides with free boundary conditions have been considered numerically. Guided modes are computed thanks to an original modeling approach also based on the hybrid (displacement/stress) vectors; interestingly, bi-orthogonality relation expressed in a discrete form is preserved. The code implementing these methods leads to fast computations of the scattering matrix of a defect; once this matrix has been computed at various frequencies, the defect

  16. Guiding, bending, and splitting of coupled defect surface modes in a surface-wave photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhen; Gao, Fei [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore 637371 (Singapore); Zhang, Baile, E-mail: blzhang@ntu.edu.sg [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore 637371 (Singapore); Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore, Singapore 637371 (Singapore)

    2016-01-25

    We experimentally demonstrate a type of waveguiding mechanism for coupled surface-wave defect modes in a surface-wave photonic crystal. Unlike conventional spoof surface plasmon waveguides, waveguiding of coupled surface-wave defect modes is achieved through weak coupling between tightly localized defect cavities in an otherwise gapped surface-wave photonic crystal, as a classical wave analogue of tight-binding electronic wavefunctions in solid state lattices. Wave patterns associated with the high transmission of coupled defect surface modes are directly mapped with a near-field microwave scanning probe for various structures including a straight waveguide, a sharp corner, and a T-shaped splitter. These results may find use in the design of integrated surface-wave devices with suppressed crosstalk.

  17. Guiding, bending, and splitting of coupled defect surface modes in a surface-wave photonic crystal

    International Nuclear Information System (INIS)

    Gao, Zhen; Gao, Fei; Zhang, Baile

    2016-01-01

    We experimentally demonstrate a type of waveguiding mechanism for coupled surface-wave defect modes in a surface-wave photonic crystal. Unlike conventional spoof surface plasmon waveguides, waveguiding of coupled surface-wave defect modes is achieved through weak coupling between tightly localized defect cavities in an otherwise gapped surface-wave photonic crystal, as a classical wave analogue of tight-binding electronic wavefunctions in solid state lattices. Wave patterns associated with the high transmission of coupled defect surface modes are directly mapped with a near-field microwave scanning probe for various structures including a straight waveguide, a sharp corner, and a T-shaped splitter. These results may find use in the design of integrated surface-wave devices with suppressed crosstalk

  18. Observation of skull-guided acoustic waves in a water-immersed murine skull using optoacoustic excitation

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2017-02-01

    The skull bone, a curved solid multilayered plate protecting the brain, constitutes a big challenge for the use of ultrasound-mediated techniques in neuroscience. Ultrasound waves incident from water or soft biological tissue are mostly reflected when impinging on the skull. To this end, skull properties have been characterized for both high-intensity focused ultrasound (HIFU) operating in the narrowband far-field regime and optoacoustic imaging applications. Yet, no study has been conducted to characterize the near-field of water immersed skulls. We used the thermoelastic effect with a 532 nm pulsed laser to trigger a wide range of broad-band ultrasound modes in a mouse skull. In order to capture the waves propagating in the near-field, a thin hydrophone was scanned in close proximity to the skull's surface. While Leaky pseudo-Lamb waves and grazing-angle bulk water waves are clearly visible in the spatio-temporal data, we were only able to identify skull-guided acoustic waves after dispersion analysis in the wavenumber-frequency space. The experimental data was found to be in a reasonable agreement with a flat multilayered plate model.

  19. Nanomedicines for the Treatment of CNS Diseases.

    Science.gov (United States)

    Reynolds, Jessica L; Mahato, Ram I

    2017-03-01

    Targeting and delivering macromolecular therapeutics to the central nervous system (CNS) has been a major challenge. The blood-brain barrier (BBB) is the main obstacle that must be overcome to allow compounds to reach their targets in the brain. Therefore, much effort has been channelled into improving transport of therapeutics across the BBB and into the CNS including the use of nanoparticles. In this thematic issue, several reviews and original research are presented that address "Nanomedicines for CNS Diseases." The articles in this issue are concentrated on either CNS-HIV disease or CNS tumors. In regards to CNS-HIV disease, there are two reviews that discuss the role of nanoparticles for improving the delivery of HIV therapeutics to the CNS. In addition, there are two original articles focusing on therapies for CNS-HIV, one of them uses nanoparticles for delivery of siRNA specific to a key protein in autophagy to microglia, and another discusses nanoparticle delivery of a soluble mediator to suppress neuroinflammation. Furthermore, a comprehensive review about gene therapy for CNS neurological diseases is also included. Finally, this issue also includes review articles on enhanced drug targeting to CNS tumors. These articles include a review on the use of nanoparticles for CNS tumors, a review on functionalization (ligands) of nanoparticles for drug targeting to the brain tumor by overcoming BBB, and the final review discusses the use of macrophages as a delivery vehicle to CNS tumors. This thematic issue provides a wealth of knowledge on using nanomedicines for CNS diseases.

  20. Characterization of Aircraft Structural Damage Using Guided Wave Based Finite Element Analysis for In-Flight Structural Health Management

    Science.gov (United States)

    Seshadri, Banavara R.; Krishnamurthy, Thiagarajan; Ross, Richard W.

    2016-01-01

    The development of multidisciplinary Integrated Vehicle Health Management (IVHM) tools will enable accurate detection, diagnosis and prognosis of damage under normal and adverse conditions during flight. The adverse conditions include loss of control caused by environmental factors, actuator and sensor faults or failures, and structural damage conditions. A major concern is the growth of undetected damage/cracks due to fatigue and low velocity foreign object impact that can reach a critical size during flight, resulting in loss of control of the aircraft. To avoid unstable catastrophic propagation of damage during a flight, load levels must be maintained that are below the load-carrying capacity for damaged aircraft structures. Hence, a capability is needed for accurate real-time predictions of safe load carrying capacity for aircraft structures with complex damage configurations. In the present work, a procedure is developed that uses guided wave responses to interrogate damage. As the guided wave interacts with damage, the signal attenuates in some directions and reflects in others. This results in a difference in signal magnitude as well as phase shifts between signal responses for damaged and undamaged structures. Accurate estimation of damage size and location is made by evaluating the cumulative signal responses at various pre-selected sensor locations using a genetic algorithm (GA) based optimization procedure. The damage size and location is obtained by minimizing the difference between the reference responses and the responses obtained by wave propagation finite element analysis of different representative cracks, geometries and sizes.

  1. Time Reversal Methods for Structural Health Monitoring of Metallic Structures Using Guided Waves

    Science.gov (United States)

    2011-09-01

    measure elastic properties of thin isotropic materials and laminated composite plates. Two types of waves propagate a symmetric wave and antisymmetric...compare it to the original signal. In this time reversal procedure wave propagation from point-A to point-B and can be modeled as a convolution ...where * is the convolution operator and transducer transmit and receive transfer function are neglected for simplification. In the frequency

  2. Modal approach for the full simulation of nondestructive tests by elastic guided waves; Approche modale pour la simulation globale de controles non-destructifs par ondes elastiques guidees

    Energy Technology Data Exchange (ETDEWEB)

    Jezzine, K

    2006-11-15

    Tools for simulating nondestructive tests by elastic guided waves are developed. Two overall formulations based on modal formalism and reciprocity are derived depending on whether transmission and reception are separated or not. They relate phenomena of guided wave radiation by a transducer, their propagation, their scattering by a non-uniformity of the guide or a defect and their reception. Receiver electrical output is expressed as a product of terms relating to each phenomenon that can be computed separately. Their computation uses developments based on the semi-analytical finite elements method, dealing with guides of arbitrary cross-section and cracks normal to the guide axis. Simulation tools are used to study means for selecting a single mode using a transducer positioned on the guide section, such a selection making easier the interpretation of the results of testing by guided waves. Two methods of mode selection are proposed, based on the use of two specific frequencies (which existence depends on guide geometry and mode symmetry). Mimicking the normal stress distribution of the mode at one of these two frequencies or the other makes it possible to radiate solely or predominantly the mode chosen. Examinations are simulated in configurations using a single or two separated transducers positioned on the section of various guide geometries and cracks of various shapes. The interest and performances of the two methods of mode selection are studied in these configurations. (author)

  3. Nonlinear Electrostatic Steepening of Whistler Waves: The Guiding Factors and Dynamics in Inhomogeneous Systems

    Science.gov (United States)

    Agapitov, O.; Drake, J. F.; Vasko, I.; Mozer, F. S.; Artemyev, A.; Krasnoselskikh, V.; Angelopoulos, V.; Wygant, J.; Reeves, G. D.

    2018-03-01

    Whistler mode chorus waves are particularly important in outer radiation belt dynamics due to their key role in controlling the acceleration and scattering of electrons over a very wide energy range. The efficiency of wave-particle resonant interactions is defined by whistler wave properties which have been described by the approximation of plane linear waves propagating through the cold plasma of the inner magnetosphere. However, recent observations of extremely high-amplitude whistlers suggest the importance of nonlinear wave-particle interactions for the dynamics of the outer radiation belt. Oblique chorus waves observed in the inner magnetosphere often exhibit drastically nonsinusoidal (with significant power in the higher harmonics) waveforms of the parallel electric field, presumably due to the feedback from hot resonant electrons. We have considered the nature and properties of such nonlinear whistler waves observed by the Van Allen Probes and Time History of Events and Macroscale Interactions define during Substorms in the inner magnetosphere, and we show that the significant enhancement of the wave electrostatic component can result from whistler wave coupling with the beam-driven electrostatic mode through the resonant interaction with hot electron beams. Being modulated by a whistler wave, the electron beam generates a driven electrostatic mode significantly enhancing the parallel electric field of the initial whistler wave. We confirm this mechanism using a self-consistent particle-in-cell simulation. The nonlinear electrostatic component manifests properties of the beam-driven electron acoustic mode and can be responsible for effective electron acceleration in the inhomogeneous magnetic field.

  4. Applications of Genomic Sequencing in Pediatric CNS Tumors.

    Science.gov (United States)

    Bavle, Abhishek A; Lin, Frank Y; Parsons, D Williams

    2016-05-01

    Recent advances in genome-scale sequencing methods have resulted in a significant increase in our understanding of the biology of human cancers. When applied to pediatric central nervous system (CNS) tumors, these remarkable technological breakthroughs have facilitated the molecular characterization of multiple tumor types, provided new insights into the genetic basis of these cancers, and prompted innovative strategies that are changing the management paradigm in pediatric neuro-oncology. Genomic tests have begun to affect medical decision making in a number of ways, from delineating histopathologically similar tumor types into distinct molecular subgroups that correlate with clinical characteristics, to guiding the addition of novel therapeutic agents for patients with high-risk or poor-prognosis tumors, or alternatively, reducing treatment intensity for those with a favorable prognosis. Genomic sequencing has also had a significant impact on translational research strategies in pediatric CNS tumors, resulting in wide-ranging applications that have the potential to direct the rational preclinical screening of novel therapeutic agents, shed light on tumor heterogeneity and evolution, and highlight differences (or similarities) between pediatric and adult CNS tumors. Finally, in addition to allowing the identification of somatic (tumor-specific) mutations, the analysis of patient-matched constitutional (germline) DNA has facilitated the detection of pathogenic germline alterations in cancer genes in patients with CNS tumors, with critical implications for genetic counseling and tumor surveillance strategies for children with familial predisposition syndromes. As our understanding of the molecular landscape of pediatric CNS tumors continues to advance, innovative applications of genomic sequencing hold significant promise for further improving the care of children with these cancers.

  5. An invertebrate model for CNS drug discovery

    DEFF Research Database (Denmark)

    Al-Qadi, Sonia; Schiøtt, Morten; Hansen, Steen Honoré

    2015-01-01

    BACKGROUND: ABC efflux transporters at the blood brain barrier (BBB), namely the P-glycoprotein (P-gp), restrain the development of central nervous system (CNS) drugs. Consequently, early screening of CNS drug candidates is pivotal to identify those affected by efflux activity. Therefore, simple,...... barriers. CONCLUSION: Findings suggest a conserved mechanism of brain efflux activity between insects and vertebrates, confirming that this model holds promise for inexpensive and high-throughput screening relative to in vivo models, for CNS drug discovery....

  6. Experimental observation of spontaneous depolarized guided acoustic-wave Brillouin scattering in side cores of a multicore fiber

    Science.gov (United States)

    Hayashi, Neisei; Mizuno, Yosuke; Nakamura, Kentaro; Set, Sze Yun; Yamashita, Shinji

    2018-06-01

    Spontaneous depolarized guided acoustic-wave Brillouin scattering (GAWBS) was experimentally observed in one of the side cores of an uncoated multicore fiber (MCF). The frequency bandwidth in the side core was up to ∼400 MHz, which is 0.5 times that in the central core. The GAWBS spectrum of the side core of the MCF included intrinsic peaks, which had different acoustic resonance frequencies from those of the central core. In addition, the spontaneous depolarized GAWBS in the central/side core was unaffected by that in the other core. These results will lead to the development of polarization/phase modulators using an MCF.

  7. Characterizing Hypervelocity Impact (HVI-Induced Pitting Damage Using Active Guided Ultrasonic Waves: From Linear to Nonlinear

    Directory of Open Access Journals (Sweden)

    Menglong Liu

    2017-05-01

    Full Text Available Hypervelocity impact (HVI, ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting damage is introduced. The pitting damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of damage (multitudinous damage within a singular inspection region, a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation are extracted, for detecting gross damage whose characteristic dimensions are comparable to the wavelength of the probing wave; nonlinear-wise, changes in the signal features in the frequency domain (e.g., second harmonic generation, which are proven to be more sensitive than their linear counterparts to small-scale damage, are explored to characterize HVI-induced pitting damage scattered in the inner layer. A numerical simulation, supplemented with experimental validation, quantitatively reveals the accumulation of nonlinearity of the guided waves when the waves traverse the pitting damage, based on which linear and nonlinear damage indices are proposed. A path-based rapid imaging algorithm, in conjunction with the use of the developed linear and nonlinear indices, is developed, whereby the HVI-induced pitting damage is characterized in images in terms of the probability of occurrence.

  8. Oral Session 03: CNS Risk

    International Nuclear Information System (INIS)

    Narici, Livio; Nelson, Gregory A.

    2014-01-01

    Exposure to space radiation may have impacts on brain function, either during or following missions. It is most important to determine how low doses of protons and high-LET irradiation elicit changes in brain function. Within this framework, the role of oxidative stress should also be assessed, as well as other possible interaction mechanisms involving, e.g., genetic, environmental, and sex-dependent risk factors. The hippocampus is particularly susceptible to radiation. It plays an essential role in memory formation and consolidation and is one of the most investigated brain components for its responses to radiation. The hippocampus is also one of the first brain structures to be damaged in the pathogenesis of Alzheimer's disease, an important potential late impairment following irradiation. In ‘Section 3: CNS risk’, six papers have been presented focused on these issues. For details the reader is directed to the specific papers. Here a very short summary follows

  9. Estimating state of charge and health of lithium-ion batteries with guided waves using built-in piezoelectric sensors/actuators

    Science.gov (United States)

    Ladpli, Purim; Kopsaftopoulos, Fotis; Chang, Fu-Kuo

    2018-04-01

    This work presents the feasibility of monitoring state of charge (SoC) and state of health (SoH) of lithium-ion pouch batteries with acousto-ultrasonic guided waves. The guided waves are propagated and sensed using low-profile, built-in piezoelectric disc transducers that can be retrofitted onto off-the-shelf batteries. Both experimental and analytical studies are performed to understand the relationship between guided waves generated in a pitch-catch mode and battery SoC/SoH. The preliminary experiments on representative pouch cells show that the changes in time of flight (ToF) and signal amplitude (SA) resulting from shifts in the guided wave signals correlate strongly with the electrochemical charge-discharge cycling and aging. An analytical acoustic model is developed to simulate the variations in electrode moduli and densities during cycling, which correctly validates the absolute values and range of experimental ToF. It is further illustrated via a statistical study that ToF and SA can be used in a prediction model to accurately estimate SoC/SoH. Additionally, by using multiple sensors in a network configuration on the same battery, a significantly more reliable and accurate SoC/SoH prediction is achieved. The indicative results from this study can be extended to develop a unified guided-wave-based framework for SoC/SoH monitoring of many lithium-ion battery applications.

  10. On Multiple Hall-Like Electron Currents and Tripolar Guide Magnetic Field Perturbations During Kelvin-Helmholtz Waves

    Science.gov (United States)

    Sturner, Andrew P.; Eriksson, Stefan; Nakamura, Takuma; Gershman, Daniel J.; Plaschke, Ferdinand; Ergun, Robert E.; Wilder, Frederick D.; Giles, Barbara; Pollock, Craig; Paterson, William R.; Strangeway, Robert J.; Baumjohann, Wolfgang; Burch, James L.

    2018-02-01

    Two magnetopause current sheet crossings with tripolar guide magnetic field signatures were observed by multiple Magnetosphere Multiscale (MMS) spacecraft during Kelvin-Helmholtz wave activity. The two out-of-plane magnetic field depressions of the tripolar guide magnetic field are largely supported by the observed in-plane electron currents, which are reminiscent of two clockwise Hall current loop systems. A comparison with a three-dimensional kinetic simulation of Kelvin-Helmholtz waves and vortex-induced reconnection suggests that MMS likely encountered the two Hall magnetic field depressions on either side of a magnetic reconnection X-line. Moreover, MMS observed an out-of-plane current reversal and a corresponding in-plane magnetic field rotation at the center of one of the current sheets, suggesting the presence of two adjacent flux ropes. The region inside one of the ion-scale flux ropes was characterized by an observed decrease of the total magnetic field, a strong axial current, and significant enhancements of electron density and parallel electron temperature. The flux rope boundary was characterized by currents opposite this axial current, strong in-plane and converging electric fields, parallel electric fields, and weak electron-frame Joule dissipation. These return current region observations may reflect a need to support the axial current rather than representing local reconnection signatures in the absence of any exhausts.

  11. Detecting delaminations and disbondings on full-scale wing composite panel by guided waves based SHM system

    Science.gov (United States)

    Monaco, E.; Boffa, N. D.; Memmolo, V.; Ricci, F.; Maio, L.

    2016-04-01

    A full-scale lower wing panel made of composite material has been designed, manufactured and sensorised within the European Funded research project named SARISTU. The authors contributed to the whole development of the system, from design to implementation as well as to the impacts campaign phase where Barely Visible and Visible Damages (BVID and VID) are to be artificially induced on the panel by a pneumatic impact machine. This work summarise part of the experimental results related to damages production, their assessment by C-SCAN as reference NDT method as well as damage detection of delimitations by a guided waves based SHM. The SHM system is made by customized piezoelectric patches secondary bonded on the wing plate acting both as guided waves sources and receivers. The paper will deal mostly with the experimental impact campaign and the signal analyses carried out to extract the metrics more sensitive to damages induced. Image reconstruction of the damages dimensions and shapes will be also described based mostly on the combination of metrics maps over the plate partial surfaces. Finally a comparison of damages maps obtained by the SHM approach and those obtained by "classic" C-SCAN will be presented analyzing briefly pros and cons of the two different approached as a combination to the most effective structural maintenance scenario of a commercial aircraft.

  12. Phased laser diode array permits selective excitation of ultrasonic guided waves in coated bone-mimicking tubes

    Science.gov (United States)

    Moilanen, Petro; Salmi, Ari; Kilappa, Vantte; Zhao, Zuomin; Timonen, Jussi; Hæggström, Edward

    2017-10-01

    This paper validates simulation predictions, which state that specific modes could be enhanced in quantitative ultrasonic bone testing. Tunable selection of ultrasonic guided wave excitation is useful in non-destructive testing since it permits the mediation of energy into diagnostically useful modes while reducing the energy mediated into disturbing contributions. For instance, it is often challenging to distinguish and extract the useful modes from ultrasound signals measured in bone covered by a soft tissue. We show that a laser diode array can selectively excite ultrasound in bone mimicking phantoms. A fiber-coupled diode array (4 elements) illuminated two solid tubes (2-3 mm wall thickness) embraced by an opaque soft-tissue mimicking elastomer coating (5 mm thick). A predetermined time delay matching the selected mode and frequency was employed between the outputs of the elements. The generated ultrasound was detected by a 215 kHz piezo receiver. Our results suggest that this array reduces the disturbances caused by the elastomer cover and so pave way to permit non-contacting in vivo guided wave ultrasound assessment of human bones. The implementation is small, inexpensive, and robust in comparison with the conventional pulsed lasers.

  13. Evaluation of pipeline defect's characteristic axial length via model-based parameter estimation in ultrasonic guided wave-based inspection

    International Nuclear Information System (INIS)

    Wang, Xiaojuan; Tse, Peter W; Dordjevich, Alexandar

    2011-01-01

    The reflection signal from a defect in the process of guided wave-based pipeline inspection usually includes sufficient information to detect and define the defect. In previous research, it has been found that the reflection of guided waves from even a complex defect primarily results from the interference between reflection components generated at the front and the back edges of the defect. The respective contribution of different parameters of a defect to the overall reflection can be affected by the features of the two primary reflection components. The identification of these components embedded in the reflection signal is therefore useful in characterizing the concerned defect. In this research, we propose a method of model-based parameter estimation with the aid of the Hilbert–Huang transform technique for the purpose of decomposition of a reflection signal to enable characterization of the pipeline defect. Once two primary edge reflection components are decomposed and identified, the distance between the reflection positions, which closely relates to the axial length of the defect, could be easily and accurately determined. Considering the irregular profiles of complex pipeline defects at their two edges, which is often the case in real situations, the average of varied axial lengths of such a defect along the circumference of the pipeline is used in this paper as the characteristic value of actual axial length for comparison purpose. The experimental results of artificial defects and real corrosion in sample pipes were considered in this paper to demonstrate the effectiveness of the proposed method

  14. The Feasibility of Structural Health Monitoring Using the Fundamental Shear Horizontal Guided Wave in a Thin Aluminum Plate

    Directory of Open Access Journals (Sweden)

    Jorge Franklin Mansur Rodrigues Filho

    2017-05-01

    Full Text Available Structural health monitoring (SHM is emerging as an essential tool for constant monitoring of safety-critical engineering components. Ultrasonic guided waves stand out because of their ability to propagate over long distances and because they can offer good estimates of location, severity, and type of damage. The unique properties of the fundamental shear horizontal guided wave (SH0 mode have recently generated great interest among the SHM community. The aim of this paper is to demonstrate the feasibility of omnidirectional SH0 SHM in a thin aluminum plate using a three-transducer sparse array. Descriptions of the transducer, the finite element model, and the imaging algorithm are presented. The image localization maps show a good agreement between the simulations and experimental results. The SH0 SHM method proposed in this paper is shown to have a high resolution and to be able to locate defects within 5% of the true location. The short input signal as well the non-dispersive nature of SH0 leads to high resolution in the reconstructed images. The defect diameter estimated using the full width at half maximum was 10 mm or twice the size of the true diameter.

  15. Guided wave radiation in a finite-sized metallic or composite plate-like structure for its nondestructive testing

    International Nuclear Information System (INIS)

    Stevenin, Mathilde

    2016-01-01

    Different models are developed to provide generic tools for simulating nondestructive methods relying on elastic guided waves applied to metallic or composite plates. Various inspection methods of these structures exist or are under study. Most of them make use of ultrasonic sources of finite size; all are sensitive to reflection phenomena resulting from the finite size of the monitored objects. The developed models deal with transducer diffraction effects and edge reflection. As the interpretation of signals measured in guided wave inspection often uses the concept of modes, the models themselves are explicitly modal. The case of isotropic plates (metal) and anisotropic (multilayer composites) are considered; a general approach under the stationary phase approximation allows us to consider all the cases of interest. For the first, the validity of a Fraunhofer-like approximation leads to a very efficient computation of the direct and reflected fields radiated by a source. For the second, special attention is paid to the treatment of caustics. The stationary phase approximation being difficult to generalize, a model (so-called 'pencil model') of more geometrical nature is proposed with a high degree of genericity. It chains terms of isotropic or anisotropic propagation and terms of interaction with a boundary. The equivalence of the stationary phase approximation and the pencil model is demonstrated in the case of the radiation and reflection in an isotropic plate, for which an experimental validation is proceeded. (author) [fr

  16. microRNAs in CNS disorders

    DEFF Research Database (Denmark)

    Kocerha, Jannet; Kauppinen, Sakari; Wahlestedt, Claes

    2009-01-01

    RNAs (miRNAs) have been identified in the mammalian central nervous system (CNS) and are reported to mediate pivotal roles in many aspects of neuronal functions. Disruption of miRNA-based post-transcriptional regulation has been implicated in a range of CNS disorders as one miRNA is predicted to impact...

  17. Measurement of guided mode wave vectors by analysis of the transfer matrix obtained with multi-emitters and multi-receivers in contact

    Energy Technology Data Exchange (ETDEWEB)

    Minonzio, Jean-Gabriel; Talmant, Maryline; Laugier, Pascal, E-mail: jean-gabriel.minonzio@upmc.fr [UPMC Univ Paris 06, UMR 7623, LIP, 15 rue de l' ecole de medecine F-75005, Paris (France)

    2011-01-01

    Different quantitative ultrasound techniques are currently developed for clinical assessment of human bone status. This paper is dedicated to axial transmission: emitters and receivers are linearly arranged on the same side of the skeletal site, preferentially the forearm. In several clinical studies, the signal velocity of the earliest temporal event has been shown to discriminate osteoporotic patients from healthy subjects. However, a multi parameter approach might be relevant to improve bone diagnosis and this be could be achieved by accurate measurement of guided waves wave vectors. For clinical purposes and easy access to the measurement site, the length probe is limited to about 10 mm. The limited number of acquisition scan points on such a short distance reduces the efficiency of conventional signal processing techniques, such as spatio-temporal Fourier transform. The performance of time-frequency techniques was shown to be moderate in other studies. Thus, optimised signal processing is a critical point for a reliable estimate of guided mode wave vectors. Toward this end, a technique, taking benefit of using both multiple emitters and multiple receivers, is proposed. The guided mode wave vectors are obtained using a projection in the singular vectors basis. Those are determined by the singular values decomposition of the transmission matrix between the two arrays at different frequencies. This technique enables us to recover accurately guided waves wave vectors for moderately large array.

  18. Simulation of guided-wave ultrasound propagation in composite laminates: Benchmark comparisons of numerical codes and experiment.

    Science.gov (United States)

    Leckey, Cara A C; Wheeler, Kevin R; Hafiychuk, Vasyl N; Hafiychuk, Halyna; Timuçin, Doğan A

    2018-03-01

    Ultrasonic wave methods constitute the leading physical mechanism for nondestructive evaluation (NDE) and structural health monitoring (SHM) of solid composite materials, such as carbon fiber reinforced polymer (CFRP) laminates. Computational models of ultrasonic wave excitation, propagation, and scattering in CFRP composites can be extremely valuable in designing practicable NDE and SHM hardware, software, and methodologies that accomplish the desired accuracy, reliability, efficiency, and coverage. The development and application of ultrasonic simulation approaches for composite materials is an active area of research in the field of NDE. This paper presents comparisons of guided wave simulations for CFRP composites implemented using four different simulation codes: the commercial finite element modeling (FEM) packages ABAQUS, ANSYS, and COMSOL, and a custom code executing the Elastodynamic Finite Integration Technique (EFIT). Benchmark comparisons are made between the simulation tools and both experimental laser Doppler vibrometry data and theoretical dispersion curves. A pristine and a delamination type case (Teflon insert in the experimental specimen) is studied. A summary is given of the accuracy of simulation results and the respective computational performance of the four different simulation tools. Published by Elsevier B.V.

  19. User guide - COE calculation tool for wave energy converters. Draft version 1

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Chozas, J.; Kofoed, J.P. [Aalborg Univ., Aalborg (Denmark); Helstrup Jensen, N.E. [Energinet.dk, Fredericia (Denmark)

    2013-08-15

    Aalborg University together with Energinet.dk and Julia F. Chozas Consulting Engineer, have released a freely available online spreadsheet to evaluate the Levelised Cost of Energy (LCOE) for wave energy projects. The open-access tool calculates the LCOE based on the power production of a Wave Energy Converter (WEC) at a particular location. Production data may derive from laboratory testing, numerical modelling or from sea trials. The tool has been developed as a transparent and simple model that evaluates WEC's economic feasibility in a range of locations, while scaling WEC's features to the selected site. (Author)

  20. Experimental and Computational Studies on the Scattering of an Edge-Guided Wave by a Hidden Crack on a Racecourse Shaped Hole.

    Science.gov (United States)

    Vien, Benjamin Steven; Rose, Louis Raymond Francis; Chiu, Wing Kong

    2017-07-01

    Reliable and quantitative non-destructive evaluation for small fatigue cracks, in particular those in hard-to-inspect locations, is a challenging problem. Guided waves are advantageous for structural health monitoring due to their slow geometrical decay of amplitude with propagating distance, which is ideal for rapid wide-area inspection. This paper presents a 3D laser vibrometry experimental and finite element analysis of the interaction between an edge-guided wave and a small through-thickness hidden edge crack on a racecourse shaped hole that occurs, in practice, as a fuel vent hole. A piezoelectric transducer is bonded on the straight edge of the hole to generate the incident wave. The excitation signal consists of a 5.5 cycle Hann-windowed tone burst of centre frequency 220 kHz, which is below the cut-off frequency for the first order Lamb wave modes (SH1). Two-dimensional fast Fourier transformation (2D FFT) is applied to the incident and scattered wave field along radial lines emanating from the crack mouth, so as to identify the wave modes and determine their angular variation and amplitude. It is shown experimentally and computationally that mid-plane symmetric edge waves can travel around the hole's edge to detect a hidden crack. Furthermore, the scattered wave field due to a small crack length, a , (compared to the wavelength λ of the incident wave) is shown to be equivalent to a point source consisting of a particular combination of body-force doublets. It is found that the amplitude of the scattered field increases quadratically as a function of a/λ , whereas the scattered wave pattern is independent of crack length for small cracks a < λ . This study of the forward scattering problem from a known crack size provides a useful guide for the inverse problem of hidden crack detection and sizing.

  1. Time domain simulation of piezoelectric excitation of guided waves in rails using waveguide finite elements

    CSIR Research Space (South Africa)

    Loveday, PW

    2007-03-01

    Full Text Available Piezoelectric transducers are commonly used to excite waves in elastic waveguides such as pipes, rock bolts and rails. While it is possible to simulate the operation of these transducers attached to the waveguide, in the time domain, using...

  2. Numerical characterisation of guided wave scattering due to welds in rails

    CSIR Research Space (South Africa)

    Long, CS

    2012-04-01

    Full Text Available The analysis of travelling waves in elastic waveguides with complex cross-sections, such as train rails, can only conveniently be performed numerically. The semi-analytical finite element (SAFE) method has become a popular tool for performing...

  3. Detection and assessment of flaws in friction stir welded joints using ultrasonic guided waves: experimental and finite element analysis

    Science.gov (United States)

    Fakih, Mohammad Ali; Mustapha, Samir; Tarraf, Jaafar; Ayoub, Georges; Hamade, Ramsey

    2018-02-01

    Ultrasonic guided waves (GWs), e.g. Lamb waves, have been proven effective in the detection of defects such as corrosion, cracking, delamination, and debonding in both composite and metallic structures. They are a significant tool employed in structural health monitoring. In this study, the ability of ultrasonic GWs to assess the quality of friction stir welding (FSW) was investigated. Four friction stir welded AZ31B magnesium plates processed with different welding parameters and a non-welded plate were used. The fundamental symmetric (S0) Lamb wave mode was excited using piezoelectric wafers (PZTs). Further, the S0 mode was separated using the "Improved complete ensemble empirical mode decomposition with adaptive noise (Improved CEEMDAN)" technique. A damage index (DI) was defined based on the variation in the amplitude of the captured wave signals in order to detect the presence and asses the severity of damage resulting from the welding process. As well, computed tomography (CT) scanning was used as a non-destructive testing (NDT) technique to assess the actual weld quality and validate predictions based on the GW approach. The findings were further confirmed using finite element analysis (FEA). To model the actual damage profile in the welds, "Mimics" software was used for the 3D reconstruction of the CT scans. The built 3D models were later used for evaluation of damage volume and for FEA. The damage volumes were correlated to the damage indices computed from both experimental and numerical data. The proposed approach showed high sensitivity of the S0 mode to internal flaws within the friction stir welded joints. This methodology has great potential as a future classification method of FSW quality.

  4. An innovative design for using flexible printed coils for magnetostrictive-based longitudinal guided wave sensors in steel strand inspection

    International Nuclear Information System (INIS)

    Tse, P W; Liu, X C; Wang, X J; Liu, Z H; Wu, B; He, C F

    2011-01-01

    Magnetostrictive sensors (MsSs) that can excite and receive guided waves are commonly used in detecting defects that may occur in cables and strands for supporting heavy structures. A conventional MsS has a hard sensing coil that is wound onto a bobbin with electric wires to generate the necessary dynamic magnetic field to excite the desired guided waves. This tailor-made hard coil is usually bulky and is not flexible enough to fit steel strands of various sizes. The conventional MsS also cannot be mounted to any steel strand that does not have a free end to allow the bobbin to pass through the structure of the tested strand. Such inflexibilities limit the use of conventional MsSs in practical situations. To solve these limitations, an innovative type of coil, called a flexible printed coil (FPC), which is made out of flexible printed film, has been designed to replace the inflexible hard coil. The flexible structure of the FPC ensures that the new MsS can be easily installed on and removed from steel strands with different diameters and without free ends. Moreover, the FPC-based MsS can be wrapped into multiple layers due to its thin and flexible design. Although multi-layer FPC creates a minor asymmetry in the dynamic magnetic field, the results of finite element analysis and experiments confirm that the longitudinal guided waves excited by a FPC-based MsS are comparable to those excited by a conventional hard coil MsS. No significant reduction in defect inspection performance was found; in fact, further advantages were identified when using the FPC-based MsS. When acting as the transmitter, the innovative FPC-based MsS can cover a longer inspection length of strand. When acting as the receiver, the FPC-based MsS is more sensitive to smaller defects that are impossible to detect using a hard coil MsS. Hence, the multi-layer FPC-based MsS has great potential for replacing the conventional hard coil MsS because of its convenient installation, and ease of fitting to

  5. Use of thin films obtained by electron beam evaporation as optical wave guide

    International Nuclear Information System (INIS)

    Nobre, S.A.A.; Oliveira, C.A.S. de; Freire, G.F.de O.

    1986-01-01

    Thin films evaporated by electron beam for the fabrication of planar optical waveguides were used. The tested materials were aluminium oxide (Al 2 O 3 ) and tantalum pentoxide (Ta 2 O 5 ). The effect of annealing conditions on the film absorption was investigated for Ta 2 O 5 . The Al 2 O 3 films were characterized by the method of guided modes, in terms of refractive index measurements and film thickness. Atenuation measurements were also carried out. (M.C.K.) [pt

  6. Development of a Modular Magnetostrictive Transducer for Torsional Guided Wave Transduction in a Cylindrical Structure

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seung Hyun; Park, Jae Ha; Kwon, Hyu Sang; Ahn, Bong Young; Lee, Seung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2009-10-15

    Cylindrical structures such as pipes and shafts are widely used in various industrial facilities. Recently, researches on magnetostrictive transduction of torsional waves have been actively reported for the nondestructive evaluation of those cylindrical structures. However, the existing magnetostrictive patch transducer has somewhat inconvenient and time. Consuming process like patch bonding to a structure since it should employ a magnetostrictive patch having strong magnetostriction. To overcome these limitations of the existing transducer, in this work, we develop a novel modular magnetostrictive transducer to generate and measure torsional waves to inspect a cylindrical structure. The proposed transducer can be applied as viscous liquid coupling with shear couplant or dry coupling without coupling media instead of patch bonding to a structure. We describe a detailed structure of the modular transducer and conduct some experiments to verify its performance

  7. Development of a Modular Magnetostrictive Transducer for Torsional Guided Wave Transduction in a Cylindrical Structure

    International Nuclear Information System (INIS)

    Cho, Seung Hyun; Park, Jae Ha; Kwon, Hyu Sang; Ahn, Bong Young; Lee, Seung Seok

    2009-01-01

    Cylindrical structures such as pipes and shafts are widely used in various industrial facilities. Recently, researches on magnetostrictive transduction of torsional waves have been actively reported for the nondestructive evaluation of those cylindrical structures. However, the existing magnetostrictive patch transducer has somewhat inconvenient and time. Consuming process like patch bonding to a structure since it should employ a magnetostrictive patch having strong magnetostriction. To overcome these limitations of the existing transducer, in this work, we develop a novel modular magnetostrictive transducer to generate and measure torsional waves to inspect a cylindrical structure. The proposed transducer can be applied as viscous liquid coupling with shear couplant or dry coupling without coupling media instead of patch bonding to a structure. We describe a detailed structure of the modular transducer and conduct some experiments to verify its performance

  8. Damage detection in multilayered fiber-metal laminates using guided-wave phased array

    Energy Technology Data Exchange (ETDEWEB)

    Maghsoodi, Ameneh; Ohadi, Abdolrezap; Sadighi, Mojtaba; Amindavar, Hamidreza [Amirkabir University, Tehran (Iran, Islamic Republic of)

    2016-05-15

    This study employs the Lamb wave method to detect damage in Fiber-metal laminates (FMLs). The method is based on quasiisotropic behavior approximation and beam forming techniques. Delay and sum and minimum variance distorsionless response beam formers are applied to a uniform linear phased array. The simulation in finite element software is conducted to evaluate the performance of the presented procedure. The two types of damage studied are the following: (1) Delamination between fiber-epoxy and metal layers and (2) crack on the metal layer. The present study has the following important contributions: (1) Health monitoring of multi-damaged FMLs using Lamb waves and beam forming technique, (2) detection of damage type, (3) detection of damage size by 1D phased array, and (4) identification of damages that occurred very close to the laminate edges or close to each other.

  9. Non-Destructive Inspection of Impact Damage in Composite Aircraft Panels by Ultrasonic Guided Waves and Statistical Processing

    Directory of Open Access Journals (Sweden)

    Margherita Capriotti

    2017-06-01

    Full Text Available This paper discusses a non-destructive evaluation (NDE technique for the detection of damage in composite aircraft structures following high energy wide area blunt impact (HEWABI from ground service equipment (GSE, such as heavy cargo loaders and other heavy equipment. The test structures typically include skin, co-cured stringers, and C-frames that are bolt-connected onto the skin with shear ties. The inspection exploits the waveguide geometry of these structures by utilizing ultrasonic guided waves and a line scan approach. Both a contact prototype and a non-contact prototype were developed and tested on realistic test panels subjected to impact in the laboratory. The results are presented in terms of receiver operating characteristic curves that show excellent probability of detection with low false alarm rates for defects located in the panel skin and stringers.

  10. Towards an Ultrasonic Guided Wave Procedure for Health Monitoring of Composite Vessels: Application to Hydrogen-Powered Aircraft.

    Science.gov (United States)

    Yaacoubi, Slah; McKeon, Peter; Ke, Weina; Declercq, Nico F; Dahmene, Fethi

    2017-09-19

    This paper presents an overview and description of the approach to be used to investigate the behavior and the defect sensitivity of various ultrasonic guided wave (UGW) modes propagating specifically in composite cylindrical vessels in the framework of the safety of hydrogen energy transportation such as hydrogen-powered aircrafts. These structures which consist of thick and multi-layer composites are envisioned for housing hydrogen gas at high pressures. Due to safety concerns associated with a weakened structure, structural health monitoring techniques are needed. A procedure for optimizing damage detection in these structural types is presented. It is shown that a finite element method can help identify useful experimental parameters including frequency range, excitation type, and receiver placement.

  11. Non-Destructive Inspection of Impact Damage in Composite Aircraft Panels by Ultrasonic Guided Waves and Statistical Processing.

    Science.gov (United States)

    Capriotti, Margherita; Kim, Hyungsuk E; Scalea, Francesco Lanza di; Kim, Hyonny

    2017-06-04

    This paper discusses a non-destructive evaluation (NDE) technique for the detection of damage in composite aircraft structures following high energy wide area blunt impact (HEWABI) from ground service equipment (GSE), such as heavy cargo loaders and other heavy equipment. The test structures typically include skin, co-cured stringers, and C-frames that are bolt-connected onto the skin with shear ties. The inspection exploits the waveguide geometry of these structures by utilizing ultrasonic guided waves and a line scan approach. Both a contact prototype and a non-contact prototype were developed and tested on realistic test panels subjected to impact in the laboratory. The results are presented in terms of receiver operating characteristic curves that show excellent probability of detection with low false alarm rates for defects located in the panel skin and stringers.

  12. Dynamic diffraction-limited light-coupling of 3D-maneuvered wave-guided optical waveguides.

    Science.gov (United States)

    Villangca, Mark; Bañas, Andrew; Palima, Darwin; Glückstad, Jesper

    2014-07-28

    We have previously proposed and demonstrated the targeted-light delivery capability of wave-guided optical waveguides (WOWs). As the WOWs are maneuvered in 3D space, it is important to maintain efficient light coupling through the waveguides within their operating volume. We propose the use of dynamic diffractive techniques to create diffraction-limited spots that will track and couple to the WOWs during operation. This is done by using a spatial light modulator to encode the necessary diffractive phase patterns to generate the multiple and dynamic coupling spots. The method is initially tested for a single WOW and we have experimentally demonstrated dynamic tracking and coupling for both lateral and axial displacements.

  13. Dynamic diffraction-limited light-coupling of 3D-maneuvered wave-guided optical waveguides

    DEFF Research Database (Denmark)

    Villangca, Mark Jayson; Bañas, Andrew Rafael; Palima, Darwin

    2014-01-01

    We have previously proposed and demonstrated the targeted-light delivery capability of wave-guided optical waveguides (WOWs). As the WOWs are maneuvered in 3D space, it is important to maintain efficient light coupling through the waveguides within their operating volume. We propose the use...... of dynamic diffractive techniques to create diffraction-limited spots that will track and couple to the WOWs during operation. This is done by using a spatial light modulator to encode the necessary diffractive phase patterns to generate the multiple and dynamic coupling spots. The method is initially tested...... for a single WOW and we have experimentally demonstrated dynamic tracking and coupling for both lateral and axial displacements....

  14. Towards an Ultrasonic Guided Wave Procedure for Health Monitoring of Composite Vessels: Application to Hydrogen-Powered Aircraft

    Directory of Open Access Journals (Sweden)

    Slah Yaacoubi

    2017-09-01

    Full Text Available This paper presents an overview and description of the approach to be used to investigate the behavior and the defect sensitivity of various ultrasonic guided wave (UGW modes propagating specifically in composite cylindrical vessels in the framework of the safety of hydrogen energy transportation such as hydrogen-powered aircrafts. These structures which consist of thick and multi-layer composites are envisioned for housing hydrogen gas at high pressures. Due to safety concerns associated with a weakened structure, structural health monitoring techniques are needed. A procedure for optimizing damage detection in these structural types is presented. It is shown that a finite element method can help identify useful experimental parameters including frequency range, excitation type, and receiver placement.

  15. Effects of Defect Size and Number Density on the Transmission and Reflection of Guided Elastic Waves

    Science.gov (United States)

    2016-04-22

    localized region, a photoacoustic source generates elastic waves on one side of the damaged region, and then two ultrasound transducers measure the...Panther OPO) operating at 1.55um and with a pulse width of 7ns, a repetition rate of 30Hz and an average power of 65mW. This configuration seems...where the defects are of the same order as the wavelength of the ultrasound , we find ourselves confronted with Mie scattering, which has weaker

  16. CNS embryonal tumours: WHO 2016 and beyond.

    Science.gov (United States)

    Pickles, J C; Hawkins, C; Pietsch, T; Jacques, T S

    2018-02-01

    Embryonal tumours of the central nervous system (CNS) present a significant clinical challenge. Many of these neoplasms affect young children, have a very high mortality and therapeutic strategies are often aggressive with poor long-term outcomes. There is a great need to accurately diagnose embryonal tumours, predict their outcome and adapt therapy to the individual patient's risk. For the first time in 2016, the WHO classification took into account molecular characteristics for the diagnosis of CNS tumours. This integration of histological features with genetic information has significantly changed the diagnostic work-up and reporting of tumours of the CNS. However, this remains challenging in embryonal tumours due to their previously unaccounted tumour heterogeneity. We describe the recent revisions made to the 4th edition of the WHO classification of CNS tumours and review the main changes, while highlighting some of the more common diagnostic testing strategies. © 2017 British Neuropathological Society.

  17. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  18. Use of Guided Acoustic Waves to Assess the Effects of Thermal-Mechanical Cycling on Composite Stiffness

    Science.gov (United States)

    Seale, Michael D.; Madaras, Eric I.

    2000-01-01

    The introduction of new, advanced composite materials into aviation systems requires it thorough understanding of the long-term effects of combined thermal and mechanical loading. As part of a study to evaluate the effects of thermal-mechanical cycling, it guided acoustic (Lamb) wave measurement system was used to measure the bending and out-of-plane stiffness coefficients of composite laminates undergoing thermal-mechanical loading. The system uses a pulse/receive technique that excites an antisymmetric Lamb mode and measures the time-of-flight over a wide frequency range. Given the material density and plate thickness, the bending and out-of-plane shear stiffnesses are calculated from a reconstruction of the velocity dispersion curve. A series of 16 and 32-ply composite laminates were subjected to it thermal-mechanical loading profile in load frames equipped with special environmental chambers. The composite systems studied were it graphite fiber reinforced amorphous thermoplastic polyimide and it graphite fiber reinforced bismaleimide thermoset. The samples were exposed to both high and low temperature extremes its well as high and low strain profiles. The bending and out-of-plane stiffnesses for composite sample that have undergone over 6,000 cycles of thermal-mechanical loading are reported. The Lamb wave generated elastic stiffness results have shown decreases of up to 20% at 4,936 loading cycles for the graphite/thermoplastic samples and up to 64% at 4,706 loading cycles for the graphite/thermoset samples.

  19. Multi-site damage localization in anisotropic plate-like structures using an active guided wave structural health monitoring system

    International Nuclear Information System (INIS)

    Moll, J; Schulte, R T; Fritzen, C-P; Hartmann, B; Nelles, O

    2010-01-01

    A new approach for structural health monitoring using guided waves in plate-like structures has been developed. In contrast to previous approaches, which mainly focused on isotropic or quasi-isotropic plates, the proposed algorithm does not assume any simplifications regarding anisotropic wave propagation. Thus, it can be used to improve the probability of detection. In this paper the mathematical background for damage localization in anisotropic plates will be introduced. This is an extension of the widely known ellipse method. The formalism is based on a distributed sensor network, where each piezoelectric sensor acts in turn as an actuator. The automatic extraction of the onset time of the first waveform in the differential signal in combination with a statistical post-processing via a two-dimensional probability density function and the application of the expectation-maximization algorithm allows a completely automatic localization procedure. Thus, multiple damages can be identified at the same time. The present study uses ultrasonic signals provided by the spectral element method. This simulation approach shows good agreement with experimental measurements. A local linear neural network is used to model the nonlinear dispersion curves. The benefit of using a neural network approach is to increase the angular resolution that results from the sparse sensor network. Furthermore, it can be used to shorten the computational time for the damage localization procedure

  20. Bistable states of TM polarized non-linear waves guided by symmetric layered structures

    International Nuclear Information System (INIS)

    Mihalache, D.

    1985-04-01

    Dispersion relations for TM polarized non-linear waves propagating in a symmetric single film optical waveguide are derived. The system consists of a layer of thickness d with dielectric constant epsilon 1 bounded at two sides by a non-linear medium characterized by the diagonal dielectric tensor epsilon 11 =epsilon 22 =epsilon 0 , epsilon 33 =epsilon 0 +α|E 3 | 2 , where E 3 is the normal electric field component. For sufficiently large d/lambda (lambda is the wavelength) we predict bistable states of both symmetric and antisymmetric modes provided that the power flow is the control parameter. (author)

  1. Detection and mode identification of axial cracks in the steam generator tube of the nuclear power plant using ultrasonic guided wave

    International Nuclear Information System (INIS)

    Yoon, Byungsik; Yang, Seunghan; Lee, Heejong; Kim, Yongsik

    2010-01-01

    For those people who are involved in NDE, there is a growing concern regarding the significant traveling distance of a guided wave in a structure, which ensures the inspection of a large area of the structure from a single location. A significant number of studies on the guided wave have therefore been made to apply the foregoing to a nondestructive evaluation in many different industries and resulted in an increase in the efficiency of practical guided wave inspection. Unlike the previous studies based mainly on the detection of circumferential flaws, this study is focused on the axial flaw detection in the steam generator tubes of Korean standard nuclear power plants by generating the guided wave by changing frequency and selecting the applicable mode from the dispersion curve for the steam generator tube calculated in this study, where the dispersion-based short-time Fourier transform (D-STFT) algorithm is used to enhance mode identification. In conclusion, the L (0,1) mode at 2.25 MHz is found to be most sensitive in detecting axial flaws in a steam generator tube. (author)

  2. Guiding electromagnetic waves around sharp corners: topologically protected photonic transport in meta-waveguides (Presentation Recording)

    Science.gov (United States)

    Shvets, Gennady B.; Khanikaev, Alexander B.; Ma, Tzuhsuan; Lai, Kueifu

    2015-09-01

    Science thrives on analogies, and a considerable number of inventions and discoveries have been made by pursuing an unexpected connection to a very different field of inquiry. For example, photonic crystals have been referred to as "semiconductors of light" because of the far-reaching analogies between electron propagation in a crystal lattice and light propagation in a periodically modulated photonic environment. However, two aspects of electron behavior, its spin and helicity, escaped emulation by photonic systems until recent invention of photonic topological insulators (PTIs). The impetus for these developments in photonics came from the discovery of topologically nontrivial phases in condensed matter physics enabling edge states immune to scattering. The realization of topologically protected transport in photonics would circumvent a fundamental limitation imposed by the wave equation: inability of reflections-free light propagation along sharply bent pathway. Topologically protected electromagnetic states could be used for transporting photons without any scattering, potentially underpinning new revolutionary concepts in applied science and engineering. I will demonstrate that a PTI can be constructed by applying three types of perturbations: (a) finite bianisotropy, (b) gyromagnetic inclusion breaking the time-reversal (T) symmetry, and (c) asymmetric rods breaking the parity (P) symmetry. We will experimentally demonstrate (i) the existence of the full topological bandgap in a bianisotropic, and (ii) the reflectionless nature of wave propagation along the interface between two PTIs with opposite signs of the bianisotropy.

  3. Omnidirectional piezo-optical ring sensor for enhanced guided wave structural health monitoring

    International Nuclear Information System (INIS)

    Giurgiutiu, Victor; Roman, Catalin; Lin, Bin; Frankforter, Erik

    2015-01-01

    This paper presents a novel method for the detection of ultrasonic waves from acoustic emission events using piezoelectric wafer ac3tive sensors (PWAS) and optical fiber Bragg grating (FBG) sensing combined with mechanical resonance amplification principles. The method is best suited for detecting the out-of-plane motion of the AE wave with preference for a certain frequency that can be adjusted by design. Several issues are discussed: (a) study the mode shapes of the sensors under different resonance frequencies in order to understand the behavior of the ring in a frequency band of interest; (b) comparison of analytical results and mode shapes with FEM predictions; (c) choice of the final piezo-optical ring sensor shape; (d) testing of the piezo-optical ring sensor prototype; (e) discussion of the ring-sensor test results in comparison with conventional results from PWAS and FBG sensors mounted directly on the test structure. The paper ends with summary, conclusions, and suggestions for further work. (paper)

  4. Guided-wave phase-matched second-harmonic generation in KTiOPO4 waveguide produced by swift heavy-ion irradiation

    Science.gov (United States)

    Cheng, Yazhou; Jia, Yuechen; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2014-11-01

    We report on the guided-wave second-harmonic generation in a KTiOPO4 nonlinear optical waveguide fabricated by a 17 MeV O5+ ion irradiation at a fluence of 1.5×1015 ions/cm2. The waveguide guides light along both TE and TM polarizations, which is suitable for phase-matching frequency doubling. Second harmonics of green light at a wavelength of 532 nm have been generated through the KTiOPO4 waveguide platform under an optical pump of fundamental wave at 1064 nm in both continuous-wave and pulsed regimes, reaching optical conversion efficiencies of 5.36%/W and 11.5%, respectively. The propagation losses have been determined to be ˜3.1 and ˜5.7 dB/cm for the TE and TM polarizations at a wavelength of 632.8 nm, respectively.

  5. Preliminary design of high-power wave-guide/transmission system for multimegawatt CW requirements of 100 MeV proton Linac

    International Nuclear Information System (INIS)

    Shrivastava, Purushottam; Wanmode, Y.D.; Hannurkar, P.R.

    2002-01-01

    Development of a 100 MeV CW proton Linac has been planned at CAT. This Linac will be needing CW rf power in the frequency ranges of 350 MHz and 700 MHz for its RFQ and DTL/CCDTL/SFDTL structures respectively. The power to the accelerating structures will be produced by either 1 MW CW or 250 kW CW klystron/inductive output tubes (HOM IOTs). The power needed by respective feed points in the structure is max. 250 kW which will be powered by splitting the power from 1 MW klystron/klystrode into four channels by using a wave-guide system. In case of using 250 kW tubes the power to the structures will be provided directly from each tube. Two types of wave-guide transmission system have been considered, viz WR 2300 for 350 MHz rf needs and WR 1500 for 700 MHz rf needs. The typical wave-guide system has been designed using the 1 MW CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window. The circulator and each power divider is terminated into the isolated ports by high power CW loads. Out of the four channels three channels have phase shifters. Present paper describes the technological aspects and design specifications-considerations for these stringent requirements. (author)

  6. Guided ultrasonic waves for determining effective orthotropic material parameters of continuous-fiber reinforced thermoplastic plates.

    Science.gov (United States)

    Webersen, Manuel; Johannesmann, Sarah; Düchting, Julia; Claes, Leander; Henning, Bernd

    2018-03-01

    Ultrasonic methods are widely established in the NDE/NDT community, where they are mostly used for the detection of flaws and structural damage in various components. A different goal, despite the similar technological approach, is non-destructive material characterization, i.e. the determination of parameters like Young's modulus. Only few works on this topic have considered materials with high damping and strong anisotropy, such as continuous-fiber reinforced plastics, but due to the increasing demand in the industry, appropriate methods are needed. In this contribution, we demonstrate the application of laser-induced ultrasonic Lamb waves for the characterization of fiber-reinforced plastic plates, providing effective parameters for a homogeneous, orthotropic material model. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. The training on propagation of guided electromagnetic waves from the point of view of LSM LSE modes; La ensenanza de las ondas electromagneticas guiadas desde el punto de vista de los modos LSM y LSE

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J.

    1997-09-01

    In this work, LSM and LSE modes are proposed as a didactic alternative for modeling the propagation of guided electromagnetic waves. Our considerations can be applied to the most common electromagnetic waves guiding systems: empty metallic waveguides, metallic waveguides partially filled with dielectrics, dielectric sheet waveguides and 3-D dielectric waveguides. In all cases, our interest is focussed on modes with a defined polarization; therefore the teaching activity can be treated from the scalar wave approximation point of view. (Author)

  8. A Helical Undulator Wave-guide Inverse Free-Electron Laser

    International Nuclear Information System (INIS)

    Rosenzweig, J.; Bodzin, N.; Frigola, P.; Musumeci, P.; Pellegrini, C.; Travish, G.; Joshi, C.; Tochitsky, S.

    2004-01-01

    With recent success in high gradient, high-energy gain IFEL experiments at the UCLA Neptune Laboratory, future experiments are now being contemplated. The Neptune IFEL was designed to use a tightly focused, highly diffracting, near-TW peak power 10 micron laser. This choice of laser focusing, driven by power-handling limitations of the optics near the interaction region, led to design and use of a very complex undulator, and to sensitivity to both laser misalignment and focusing errors. As these effects limited the performance of the IFEL experiment, a next generation experiment at Neptune has been studied which avoids the use of a highly diffractive laser beam through use of a waveguide. We discuss here the choice of low-loss waveguide, guided mode characteristics and likely power limitations. We also examine a preferred undulator design, which is chosen to be helical in order to maximize the acceleration achieved for a given power. With the limitations of these laser and undulator choices in mind, we show the expected performance of the IFEL using 1D simulations. Three-dimensional effects are examined, in the context of use of a solenoid for focusing and acceleration enhancement

  9. A novel damage index for damage identification using guided waves with application in laminated composites

    International Nuclear Information System (INIS)

    Torkamani, Shahab; Roy, Samit; Barkey, Mark E; Sazonov, Edward; Burkett, Susan; Kotru, Sushma

    2014-01-01

    In the current investigation, an innovative time-domain damage index is introduced for the first time which is based on local statistical features of the waveform. This damage index is called the ‘normalized correlation moment’ (NCM) and is composed of the nth moment of the cross-correlation of the baseline and comparison waves. The performance of this novel damage index is compared for some synthetic signals with that of an existing damage index based on the Pearson correlation coefficient (signal difference coefficient, SDC). The proposed damage index is shown to have significant advantages over the SDC, including sensitivity to the attenuation of the signal and lower sensitivity to the signal’s noise level. Numerical simulations using Abaqus finite element (FE) software show that this novel damage index is not only capable of detecting the delamination type of damage, but also exhibits a good ability in the assessment of this type of damage in laminated composite structures. The NCM damage index is also validated using experimental data for identification of delamination in composites. (paper)

  10. Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode.

    Science.gov (United States)

    Chang, Feng-Yu; Tsai, Meng-Tsan; Wang, Zu-Yi; Chi, Chun-Kai; Lee, Cheng-Kuang; Yang, Chih-Hsun; Chan, Ming-Che; Lee, Ya-Ju

    2015-11-16

    Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery. Instead of high-cost pulsed lasers, continuous-wave laser diodes (CW-LDs) with the central wavelengths of 450 nm and 532 nm are used for blood coagulation, corresponding to higher absorption coefficients of oxyhemoglobin and deoxyhemoglobin. Experimental results showed that the location of laser exposure can be accurately controlled with the proposed approach of imaging-based feedback positioning. Moreover, blood coagulation can be efficiently induced by CW-LDs and the coagulation process can be monitored in real-time with OCT. This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging.

  11. Imaging of the neonatal CNS

    International Nuclear Information System (INIS)

    Simbrunner, J; Riccabona, M

    2006-01-01

    Imaging of the central nervous system is one of the major tasks of Paediatric Radiology, particularly in newborns, who present with a variety of conditions that need more or less urgent imaging. Imaging is usually performed primarily by bedside US, in rare cases supplemented by a skull or spine radiograph. For more detailed information and preoperatively, MRI has become the neuroimaging tool. Thus, CT today is only used for acute trauma assessment, for assessment of potential cerebral calcifications or when MRI is not available. In cases with vascular anomalies or unsuccessful punctures, image guided interventions (embolisation) or image guidance for access (lumbar puncture, puncture of skull collections ...) may become necessary. This article tries to give a brief overview on the common disease entities, their typical imaging features in the major modalities applied and the implications of imaging potential for indication and choice of imaging method. In general, acute assessment may become everywhere and major features of important diseases should be recognised not to miss conditions which need urgent treatment or referral to a dedicated paediatric unit. Many other conditions will only be seen at centres with a dedicated neonatal care unit and dedicated paediatric radiologist who then also will be able to provide proper imaging with adapted protocols and methods for these partially severely sick babies. As these specific features and adapted capabilities as well as dedicated training and clinical experience are necessary for providing best results and proper handling in neonates, many neonatal conditions will not be imaged at a peripheral site, but primarily should be referred to a paediatric (radiology) centre

  12. Guided waves based SHM systems for composites structural elements: statistical analyses finalized at probability of detection definition and assessment

    Science.gov (United States)

    Monaco, E.; Memmolo, V.; Ricci, F.; Boffa, N. D.; Maio, L.

    2015-03-01

    Maintenance approaches based on sensorised structures and Structural Health Monitoring systems could represent one of the most promising innovations in the fields of aerostructures since many years, mostly when composites materials (fibers reinforced resins) are considered. Layered materials still suffer today of drastic reductions of maximum allowable stress values during the design phase as well as of costly and recurrent inspections during the life cycle phase that don't permit of completely exploit their structural and economic potentialities in today aircrafts. Those penalizing measures are necessary mainly to consider the presence of undetected hidden flaws within the layered sequence (delaminations) or in bonded areas (partial disbonding); in order to relax design and maintenance constraints a system based on sensors permanently installed on the structure to detect and locate eventual flaws can be considered (SHM system) once its effectiveness and reliability will be statistically demonstrated via a rigorous Probability Of Detection function definition and evaluation. This paper presents an experimental approach with a statistical procedure for the evaluation of detection threshold of a guided waves based SHM system oriented to delaminations detection on a typical wing composite layered panel. The experimental tests are mostly oriented to characterize the statistical distribution of measurements and damage metrics as well as to characterize the system detection capability using this approach. Numerically it is not possible to substitute part of the experimental tests aimed at POD where the noise in the system response is crucial. Results of experiments are presented in the paper and analyzed.

  13. Numerical and Experimental Identification of Seven-Wire Strand Tensions Using Scale Energy Entropy Spectra of Ultrasonic Guided Waves

    Directory of Open Access Journals (Sweden)

    Ji Qian

    2018-01-01

    Full Text Available Accurate identification of tension in multiwire strands is a key issue to ensure structural safety and durability of prestressed concrete structures, cable-stayed bridges, and hoist elevators. This paper proposes a method to identify strand tensions based on scale energy entropy spectra of ultrasonic guided waves (UGWs. A numerical method was first developed to simulate UGW propagation in a seven-wire strand, employing the wavelet transform to extract UGW time-frequency energy distributions for different loadings. Mode separation and frequency band loss of L(0,1 were then found for increasing tension, and UGW scale energy entropy spectra were extracted to establish a tension identification index. A good linear relationship was found between the proposed identification index and tensile force, and effects of propagation distance and propagation path were analyzed. Finally, UGWs propagation was examined experimentally for a long seven-wire strand to investigate attenuation and long distance propagation. Numerical and experimental results verified that the proposed method not only can effectively identify strand tensions but can also adapt to long distance tests for practical engineering.

  14. Metallothionein expression and roles in the CNS

    DEFF Research Database (Denmark)

    Penkowa, Milena

    2002-01-01

      Metallothioneins (MTs) are low-molecular-weight (6-7 kDa) nonenzymatic proteins (60-68 amino acid residues, 25-30% being cysteine) expressed ubiquitous in the animal kingdom. In the central nervous system (CNS), three MT isoforms are known, namely MT-I to MT-III. MT-I and MT-II (MT...

  15. A method for the measurement of dispersion curves of circumferential guided waves radiating from curved shells: experimental validation and application to a femoral neck mimicking phantom

    Science.gov (United States)

    Nauleau, Pierre; Minonzio, Jean-Gabriel; Chekroun, Mathieu; Cassereau, Didier; Laugier, Pascal; Prada, Claire; Grimal, Quentin

    2016-07-01

    Our long-term goal is to develop an ultrasonic method to characterize the thickness, stiffness and porosity of the cortical shell of the femoral neck, which could enhance hip fracture risk prediction. To this purpose, we proposed to adapt a technique based on the measurement of guided waves. We previously evidenced the feasibility of measuring circumferential guided waves in a bone-mimicking phantom of a circular cross-section of even thickness. The goal of this study is to investigate the impact of the complex geometry of the femoral neck on the measurement of guided waves. Two phantoms of an elliptical cross-section and one phantom of a realistic cross-section were investigated. A 128-element array was used to record the inter-element response matrix of these waveguides. This experiment was simulated using a custom-made hybrid code. The response matrices were analyzed using a technique based on the physics of wave propagation. This method yields portions of dispersion curves of the waveguides which were compared to reference dispersion curves. For the elliptical phantoms, three portions of dispersion curves were determined with a good agreement between experiment, simulation and theory. The method was thus validated. The characteristic dimensions of the shell were found to influence the identification of the circumferential wave signals. The method was then applied to the signals backscattered by the superior half of constant thickness of the realistic phantom. A cut-off frequency and some portions of modes were measured, with a good agreement with the theoretical curves of a plate waveguide. We also observed that the method cannot be applied directly to the signals backscattered by the lower half of varying thicknesses of the phantom. The proposed approach could then be considered to evaluate the properties of the superior part of the femoral neck, which is known to be a clinically relevant site.

  16. Autologous US-guided PRP injection versus US-guided focal extracorporeal shock wave therapy for chronic lateral epicondylitis: A minimum of 2-year follow-up retrospective comparative study.

    Science.gov (United States)

    Alessio-Mazzola, Mattia; Repetto, Ilaria; Biti, Besmir; Trentini, Roberto; Formica, Matteo; Felli, Lamberto

    2018-01-01

    To compare the efficacy of two independent groups of patients treated with ultrasound (US)-guided extracorporeal shock wave (ESW) therapy and with US-guided injection of platelet-rich plasma (PRP) for chronic lateral epicondylitis (LE) with a minimum of 2-year follow-up. We retrospectively evaluated 63 patients treated for chronic LE (31 patients with autologous US-guided PRP injection and 32 patients with US-guided focal ESW therapy) from 2009 to 2014. All the patients were evaluated by means of Roles-Maudsley (RM) score, quick Disabilities of Arm, Shoulder, and Hand (QuickDASH) score, visual analogic scale (VAS) and patient-rated tennis elbow evaluation (PRTEE) to retrospectively assess the pain relief, level of activity, the self-reported function and subjective satisfaction at minimum of 2-year follow-up. Both US-guided autologous PRP injection and US-guided focal ESW administration proved effective in chronic LE with significant improvement in the QuickDASH, VAS, RM and PRTEE scores ( p 0.05). The mean time between treatment and symptom resolution was significantly shorter for the PRP treatment ( p = 0.0212); furthermore, the mean time to return to the normal activities was quicker for PRP group ( p = 0.0119). Both PRP injection and ESW therapy are feasible and safe options for the treatment of chronic LE with low risk of complications and with good long-term follow-up results. US-guided PRP injection has quick efficacy when compared with US-guided focal ESW therapy.

  17. CNS penetration of ART in HIV-infected children

    NARCIS (Netherlands)

    van den Hof, Malon; Blokhuis, Charlotte; Cohen, Sophie; Scherpbier, Henriette J.; Wit, Ferdinand W. N. M.; Pistorius, M. C. M.; Kootstra, Neeltje A.; Teunissen, Charlotte E.; Mathot, Ron A. A.; Pajkrt, Dasja

    2018-01-01

    Background: Paediatric data on CNS penetration of antiretroviral drugs are scarce. Objectives: To evaluate CNS penetration of antiretroviral drugs in HIV-infected children and explore associations with neurocognitive function. Patients and methods: Antiretroviral drug levels were measured in paired

  18. CNS adverse events associated with antimalarial agents. Fact or fiction?

    NARCIS (Netherlands)

    Phillips-Howard, P. A.; ter Kuile, F. O.

    1995-01-01

    CNS adverse drug events are dramatic, and case reports have influenced clinical opinion on the use of antimalarials. Malaria also causes CNS symptoms, thus establishing causality is difficult. CNS events are associated with the quinoline and artemisinin derivatives. Chloroquine, once considered too

  19. CNS effects following the treatment of malignancy

    International Nuclear Information System (INIS)

    Rane, N.; Quaghebeur, G.

    2012-01-01

    Corporeal and central nervous system (CNS) axis chemotherapy and radiotherapy have long been used for the effective treatment and prophylaxis of CNS, body malignancies, and leukaemias. However, they are not without their problems. Following the proliferation of magnetic resonance neuroimaging in recent years it has become clear that the spectrum of toxicity that these therapies produce ranges from subclinical white matter changes to overt brain necrosis. The effects are both direct and indirect and via different pathological mechanisms. Chronic and progressive changes can be detected many years after the initial intervention. In addition to leucoencephalopathic changes, grey matter changes are now well described. Changes may be difficult to distinguish from tumour recurrence, though may be reversible and remediable, and are thus very important to differentiate. In this review toxic effects are classified and their imaging appearances discussed, with reference to specific syndromes.

  20. Therapeutic potential of agmatine for CNS disorders.

    Science.gov (United States)

    Neis, Vivian B; Rosa, Priscila B; Olescowicz, Gislaine; Rodrigues, Ana Lúcia S

    2017-09-01

    Agmatine is a neuromodulator that regulates multiple neurotransmitters and signaling pathways. Several studies have focused on elucidating the mechanisms underlying the neuroprotective effects of this molecule, which seems to be mediated by a reduction in oxidative damage, neuroinflammation, and proapoptotic signaling. Since these events are implicated in acute and chronic excitotoxicity-related disorders (ischemia, epilepsy, traumatic brain injury, spinal cord injury, neurodegenerative, and psychiatric disorders) as well as in nociception, agmatine has been proposed as a therapeutic strategy for the treatment of central nervous system (CNS) disorders. Agmatine also stimulates the expression of trophic factors and adult neurogenesis, contributing to its ability to induce endogenous repair mechanisms. Therefore, considering its wide range of biological effects, this review summarizes the current knowledge about its protective and regenerative properties in the CNS. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. VIIP: Central Nervous System (CNS) Modeling

    Science.gov (United States)

    Vera, Jerry; Mulugeta, Lealem; Nelson, Emily; Raykin, Julia; Feola, Andrew; Gleason, Rudy; Samuels, Brian; Ethier, C. Ross; Myers, Jerry

    2015-01-01

    Current long-duration missions to the International Space Station and future exploration-class missions beyond low-Earth orbit expose astronauts to increased risk of Visual Impairment and Intracranial Pressure (VIIP) syndrome. It has been hypothesized that the headward shift of cerebrospinal fluid (CSF) and blood in microgravity may cause significant elevation of intracranial pressure (ICP), which in turn may then induce VIIP syndrome through interaction with various biomechanical pathways. However, there is insufficient evidence to confirm this hypothesis. In this light, we are developing lumped-parameter models of fluid transport in the central nervous system (CNS) as a means to simulate the influence of microgravity on ICP. The CNS models will also be used in concert with the lumped parameter and finite element models of the eye described in the related IWS works submitted by Nelson et al., Feola et al. and Ethier et al.

  2. Interneuron progenitor transplantation to treat CNS dysfunction

    Directory of Open Access Journals (Sweden)

    Muhammad O Chohan

    2016-08-01

    Full Text Available Due to the inadequacy of endogenous repair mechanisms diseases of the nervous system remain a major challenge to scientists and clinicians. Stem cell based therapy is an exciting and viable strategy that has been shown to ameliorate or even reverse symptoms of CNS dysfunction in preclinical animal models. Of particular importance has been the use of GABAergic interneuron progenitors as a therapeutic strategy. Born in the neurogenic niches of the ventral telencephalon, interneuron progenitors retain their unique capacity to disperse, integrate and induce plasticity in adult host circuitries following transplantation. Here we discuss the potential of interneuron based transplantation strategies as it relates to CNS disease therapeutics. We also discuss mechanisms underlying their therapeutic efficacy and some of the challenges that face the field.

  3. Cerebral blood flow variations in CNS lupus

    International Nuclear Information System (INIS)

    Kushner, M.J.; Tobin, M.; Fazekas, F.; Chawluk, J.; Jamieson, D.; Freundlich, B.; Grenell, S.; Freemen, L.; Reivich, M.

    1990-01-01

    We studied the patterns of cerebral blood flow (CBF), over time, in patients with systemic lupus erythematosus and varying neurologic manifestations including headache, stroke, psychosis, and encephalopathy. For 20 paired xenon-133 CBF measurements, CBF was normal during CNS remissions, regardless of the symptoms. CBF was significantly depressed during CNS exacerbations. The magnitude of change in CBF varied with the neurologic syndrome. CBF was least affected in patients with nonspecific symptoms such as headache or malaise, whereas patients with encephalopathy or psychosis exhibited the greatest reductions in CBF. In 1 patient with affective psychosis, without clinical or CT evidence of cerebral ischemia, serial SPECT studies showed resolution of multifocal cerebral perfusion defects which paralleled clinical recovery

  4. Treatment options for Primary CNS Lymphoma.

    Science.gov (United States)

    Laghari, Altaf Ali; Ahmed, Syed Ijlal; Jabbar, Adnan; Shamim, Muhammad Shahzad

    2018-03-01

    Primary CNS lymphoma (PCNSL) is a rare and aggressive brain tumour that is uniformly fatal. The rarity of the disease and the poor response to treatment makes it difficult to reach a consensus with regards to treatment options. In this review, the authors have discussed different treatment modalities used in the management of PCNSL including chemotherapy, surgery and radiation, as well as the results of recent clinical trials on treatment options for PCNSL.

  5. Comparison and analysis of FDA reported visual outcomes of the three latest platforms for LASIK: wavefront guided Visx iDesign, topography guided WaveLight Allegro Contoura, and topography guided Nidek EC-5000 CATz

    Directory of Open Access Journals (Sweden)

    Moshirfar M

    2017-01-01

    Full Text Available Majid Moshirfar,1,2 Tirth J Shah,3 David Franklin Skanchy,4 Steven H Linn,1 Paul Kang,3 Daniel S Durrie5 1HDR Research Center, Hoopes Vision, Salt Lake City, UT, 2Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, 3University of Arizona College of Medicine – Phoenix, Phoenix, AZ, 4McGovern Medical School, The University of Texas Health Science Center at Houston, TX, 5Durrie Vision, Kansas City, KS, USA Purpose: To compare and analyze the differences in visual outcomes between Visx iDesign Advanced WaveScan Studio™ System, Alcon Wavelight Allegro Topolyzer and Nidek EC-5000 using Final Fit™ Custom Ablation Treatment Software from the submitted summary of safety and effectiveness of the US Food and Drug Administration (FDA data.Methods: In this retrospective comparative study, 334 eyes from Visx iDesign, 212 eyes from Alcon Contour, and 135 eyes from Nidek CATz platforms were analyzed for primary and secondary visual outcomes. These outcomes were compared via side-by-side graphical and tabular representation of the FDA data. Statistical significance was calculated when appropriate to assess differences. A P-value <0.05 was considered statistically significant. Results: The mean postoperative uncorrected distance visual acuity (UDVA at 12 months was 20/19.25±8.76, 20/16.59±5.94, and 20/19.17±4.46 for Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. In at least 90% of treated eyes at 3 months and 12 months, all three lasers showed either no change or a gain of corrected distance visual acuity (CDVA. Mesopic contrast sensitivity at 6 months showed a clinically significant increase of 41.3%, 25.1%, and 10.6% for eyes using Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. Photopic contrast sensitivity at 6 months showed a clinically significant increase of 19.2%, 31.9%, and 10.6% for eyes using Visx iDesign, Alcon Contoura, and Nidek CATz

  6. Prophylactic CNS therapy in childhood leukemia

    International Nuclear Information System (INIS)

    Yokoyama, Takashi; Hiyoshi, Yasuhiko; Fujimoto, Takeo

    1982-01-01

    This study was designed to evaluate the efficacy of CNS-prophylaxis with high-dose methotrexate (MTX). Seventy children with previously untreated acute lymphoblastic leukemia (ALL) entered to this study between July 1978 and December 1980. According to initial white blood count (WBC), they were stratified to induce remission with; vincristine and prednine in low initial WBC ( lt 25,000/mm 3 ) group and these two agents plus adriamycin in high initial WBC ( gt 25,000/mm 3 ) group. After inducing remission, 62 children who achieved CR, received different CNS-prophlaxis; using a regimen of three doses of weekly high-dose MTX (1,000 mg/m 2 ) 6-hour infusion, which was repeated every 12 weeks-Group A (n = 14); high-dose MTX followed by 2400 rad cranial irradiation plus three doses of i.t. MT X-Group B (n = 15), 2400 rad cranial irradiation plus three doses of i.t. MTX-Group C (n = 16), and in 17 patients with high initial WBC, same as in Group A-Group D (n = 17). During an intravenous 6-h infusion of MTX at a dose of 1,000 mg/m 2 , the CSF concentration of MTX rose to 2.3 +- 2.4 x 10 -6 M after initiation of infusion and remained in 10 -7 M level for 48 hours. CNS-leukemia terminated complete remission in one of 14 children in Group A, two of 15 in Group B, two of 16 in Group C and two of 17 in Group D. The cumulative incidence of CNS-leukemia at 20 months calculated by the technique of Kaplan and Meier was 0% i n Group A, 18.1% in Group B, 7.1% in Group C and 50.8% in Group D. There was no statistical difference among Groups A, B and C. These data suggested that CNS-prophylaxis with high-dose intravenous MTX was effective as well as 2400 rad cranial irradiation plus three doses of i.t. MTX in childhood ALL with low initial WBC. (author)

  7. Central Nervous System (CNS Disease Triggering Takotsubo Syndrome

    Directory of Open Access Journals (Sweden)

    Josef Finsterer

    2016-01-01

    Full Text Available Takotsubo syndrome (TTS is usually triggered by psychological or physical stress. One of the many physical sources of stress are central nervous system (CNS disorders. CNS disorders most frequently triggering TTS include subarachnoid bleeding, epilepsy, ischemic stroke, migraine, and intracerebral bleeding. More rare CNS-triggers of TTS include posterior reversible encephalopathy syndrome (PRES, amyotrophic lateral sclerosis, encephalitis, or traumatic brain or spinal cord injury. TTS triggered by any of the CNS disorders needs to be recognized since adequate treatment of TTS may improve the general outcome from the CNS disorder as well. Neurologists need to be aware of TTS as a complication of specific CNS disorders but TTS may be triggered also by CNS disorders so far not recognised as causes of TTS.

  8. SINS/CNS Nonlinear Integrated Navigation Algorithm for Hypersonic Vehicle

    Directory of Open Access Journals (Sweden)

    Yong-jun Yu

    2015-01-01

    Full Text Available Celestial Navigation System (CNS has characteristics of accurate orientation and strong autonomy and has been widely used in Hypersonic Vehicle. Since the CNS location and orientation mainly depend upon the inertial reference that contains errors caused by gyro drifts and other error factors, traditional Strap-down Inertial Navigation System (SINS/CNS positioning algorithm setting the position error between SINS and CNS as measurement is not effective. The model of altitude azimuth, platform error angles, and horizontal position is designed, and the SINS/CNS tightly integrated algorithm is designed, in which CNS altitude azimuth is set as measurement information. GPF (Gaussian particle filter is introduced to solve the problem of nonlinear filtering. The results of simulation show that the precision of SINS/CNS algorithm which reaches 130 m using three stars is improved effectively.

  9. Electrophysiological CNS-processes related to associative learning in humans.

    Science.gov (United States)

    Christoffersen, Gert R J; Schachtman, Todd R

    2016-01-01

    The neurophysiology of human associative memory has been studied with electroencephalographic techniques since the 1930s. This research has revealed that different types of electrophysiological processes in the human brain can be modified by conditioning: sensory evoked potentials, sensory induced gamma-band activity, periods of frequency-specific waves (alpha and beta waves, the sensorimotor rhythm and the mu-rhythm) and slow cortical potentials. Conditioning of these processes has been studied in experiments that either use operant conditioning or repeated contingent pairings of conditioned and unconditioned stimuli (classical conditioning). In operant conditioning, the appearance of a specific brain process is paired with an external stimulus (neurofeedback) and the feedback enables subjects to obtain varying degrees of control of the CNS-process. Such acquired self-regulation of brain activity has found practical uses for instance in the amelioration of epileptic seizures, Autism Spectrum Disorders (ASD) and Attention Deficit Hyperactivity Disorder (ADHD). It has also provided communicative means of assistance for tetraplegic patients through the use of brain computer interfaces. Both extra and intracortically recorded signals have been coupled with contingent external feedback. It is the aim for this review to summarize essential results on all types of electromagnetic brain processes that have been modified by classical or operant conditioning. The results are organized according to type of conditioned EEG-process, type of conditioning, and sensory modalities of the conditioning stimuli. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Lesion stiffness measured by shear-wave elastography: Preoperative predictor of the histologic underestimation of US-guided core needle breast biopsy.

    Science.gov (United States)

    Park, Ah Young; Son, Eun Ju; Kim, Jeong-Ah; Han, Kyunghwa; Youk, Ji Hyun

    2015-12-01

    To determine whether lesion stiffness measured by shear-wave elastography (SWE) can be used to predict the histologic underestimation of ultrasound (US)-guided 14-gauge core needle biopsy (CNB) for breast masses. This retrospective study enrolled 99 breast masses from 93 patients, including 40 high-risk lesions and 59 ductal carcinoma in situ (DCIS), which were diagnosed by US-guided 14-gauge CNB. SWE was performed for all breast masses to measure quantitative elasticity values before US-guided CNB. To identify the preoperative factors associated with histologic underestimation, patients' age, symptoms, lesion size, B-mode US findings, and quantitative SWE parameters were compared according to the histologic upgrade after surgery using the chi-square test, Fisher's exact test, or independent t-test. The independent factors for predicting histologic upgrade were evaluated using multivariate logistic regression analysis. The underestimation rate was 28.3% (28/99) in total, 25.0% (10/40) in high-risk lesions, and 30.5% (18/59) in DCIS. All elasticity values of the upgrade group were significantly higher than those of the non-upgrade group (PBreast lesion stiffness quantitatively measured by SWE could be helpful to predict the underestimation of malignancy in US-guided 14-gauge CNB. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  11. Immune regulation and CNS autoimmune disease

    DEFF Research Database (Denmark)

    Antel, J P; Owens, T

    1999-01-01

    The central nervous system is a demonstrated target of both clinical and experimental immune mediated disorders. Immune regulatory mechanisms operative at the levels of the systemic immune system, the blood brain barrier, and within the CNS parenchyma are important determinants of the intensity...... and duration of the tissue directed injury. Convergence of research, involving direct manipulation of specific cells and molecular mediators in animal models and in vitro analysis of human immune and neural cells and tissues, is providing increasing insight into the role of these immune regulatory functions...

  12. Novel agents in CNS myeloma treatment.

    Science.gov (United States)

    Gozzetti, Alessandro; Cerase, Alfonso

    2014-01-01

    Central nervous system localization of multiple myeloma (CNS-MM) accounts for about 1% of all MM.Treatment is still unsatisfactory. Many treatments have been described in the literature: chemotherapy (CHT), intrathecal therapy (IT), and radiotherapy (RT), with survivals reported between one month and six months. Recent drugs such as the immunomodulatory drugs (IMiDs) and proteasome inhibitors (bortezomib) have changed the treatment of patients with MM, both younger and older, with a significant improvement in response and survival. The activity of new drugs in CNSMM has been reported but is still not well known. Bortezomib does not cross the blood brain barrier (BBB), and IMID’s seem to have only a minimal crossover. The role of novel agents in CNS MM management will be discussed as well as the potential role of other new immunomodulatory drugs (pomalidomide) and proteasome inhibitors that seem to cross the BBB and hold promise into the treatment of this rare and still incurable localization of the disease.

  13. Malignant lymphoma in central nervous system (CNS)

    International Nuclear Information System (INIS)

    Fujiyoshi, Kenji; Fukuyama, Hidenao; Akiguchi, Ichiro; Kameyama, Masakuni; Nishimura, Toshio.

    1984-01-01

    A 71-year-old male was admitted to Kohka Public Hospital on January 4, 1980, because of frequent vomiting and recent memory loss. Two weeks before admission upper G-I series showed no abnormalities. Physical and neurological examinations revealed no abnormalities except for slightly apathetic appearance and recent memory loss. Mild pleocytosis and marked increase of protein in CSF were observed. CT scan on January 17 showed high density areas in both medial sides of temporal lobes with remarkable contrast enhancement. His memory and, consciousness disturbances gradually aggravated, accompanied by abnormal density spreading around the ventricle walls like ventriculitis. He was transfered to Kyoto University Hospital on March 17, and malignant lymphoma was diagnosed on the basis of CSF cytology. Radiation and chemotherapy alleviated the CNS involvement and he regained normal mental function. On June 16, he developed pneumonia followed by status epilepticus. Autopsy findings revealed no lymphoid cell infiltration, but fibrous tissues in both hippocampal gyri and lymphomatous cells in the liver, which could not be suspected on clinical examinations. Apparent malignant lymphoma cells were not found in lymph nodes. This case indicated peculiar evolution of malignant lymphoma from liver to CNS or vice versa. We could not decide which organ was primary. CT findings of this case was very interesting; they resembled ventriculitis, which simulate tumors such as medulloblastoma or ependymoma spreading under ependymal lining. (author)

  14. Monitoring of surface-fatigue crack propagation in a welded steel angle structure using guided waves and principal component analysis

    Science.gov (United States)

    Lu, Mingyu; Qu, Yongwei; Lu, Ye; Ye, Lin; Zhou, Limin; Su, Zhongqing

    2012-04-01

    An experimental study is reported in this paper demonstrating monitoring of surface-fatigue crack propagation in a welded steel angle structure using Lamb waves generated by an active piezoceramic transducer (PZT) network which was freely surface-mounted for each PZT transducer to serve as either actuator or sensor. The fatigue crack was initiated and propagated in welding zone of a steel angle structure by three-point bending fatigue tests. Instead of directly comparing changes between a series of specific signal segments such as S0 and A0 wave modes scattered from fatigue crack tips, a variety of signal statistical parameters representing five different structural status obtained from marginal spectrum in Hilbert-huang transform (HHT), indicating energy progressive distribution along time period in the frequency domain including all wave modes of one wave signal were employed to classify and distinguish different structural conditions due to fatigue crack initiation and propagation with the combination of using principal component analysis (PCA). Results show that PCA based on marginal spectrum is effective and sensitive for monitoring the growth of fatigue crack although the received signals are extremely complicated due to wave scattered from weld, multi-boundaries, notch and fatigue crack. More importantly, this method indicates good potential for identification of integrity status of complicated structures which cause uncertain wave patterns and ambiguous sensor network arrangement.

  15. A diagnostic imaging approach for online characterization of multi-impact in aircraft composite structures based on a scanning spatial-wavenumber filter of guided wave

    Science.gov (United States)

    Ren, Yuanqiang; Qiu, Lei; Yuan, Shenfang; Su, Zhongqing

    2017-06-01

    Monitoring of impact and multi-impact in particular in aircraft composite structures has been an intensive research topic in the field of guided-wave-based structural health monitoring (SHM). Compared with the majority of existing methods such as those using signal features in the time-, frequency- or joint time-frequency domain, the approach based on spatial-wavenumber filter of guided wave shows superb advantage in effectively distinguishing particular wave modes and identifying their propagation direction relative to the sensor array. However, there exist two major issues when conducting online characterization of multi-impact event. Firstly, the spatial-wavenumber filter should be realized in the situation that the wavenumber of high spatial resolution of the complicated multi-impact signal cannot be measured or modeled. Secondly, it's difficult to identify the multiple impacts and realize multi-impact localization due to the overlapping of wavenumbers. To address these issues, a scanning spatial-wavenumber filter based diagnostic imaging method for online characterization of multi-impact event is proposed to conduct multi-impact imaging and localization in this paper. The principle of the scanning filter for multi-impact is developed first to conduct spatial-wavenumber filtering and to achieve wavenumber-time imaging of the multiple impacts. Then, a feature identification method of multi-impact based on eigenvalue decomposition and wavenumber searching is presented to estimate the number of impacts and calculate the wavenumber of the multi-impact signal, and an image mapping method is proposed as well to convert the wavenumber-time image to an angle-distance image to distinguish and locate the multiple impacts. A series of multi-impact events are applied to a carbon fiber laminate plate to validate the proposed methods. The validation results show that the localization of the multiple impacts are well achieved.

  16. Transplanting oligodendrocyte progenitors into the adult CNS

    International Nuclear Information System (INIS)

    Franklin, R.J.M.; Blakemore, W.F.; Cambridge Univ.

    1997-01-01

    This review covers a number of aspects of the behaviour of oligodendrocyte progenitors following transplantation into the adult CNS. First, an account is given of the ability of transplanted oligodendrocyte progenitors, grown in tissue culture in the presence of PDGF and bFGF, to extensively remyelinate focal areas of persistent demyelination. Secondly, we describe how transplanted clonal cell lines of oligodendrocyte progenitors will differentiate in to astrocytes as will oligodendrocytes following transplantation into pathological environments in which both oligodendrocytes and astrocytes are absent, thereby manifesting the bipotentially demonstrable in vitro but not during development. Finally, a series of studies examining the migratory behaviour of transplanted oligodendrocyte progenitors (modelled using the oligodendrocyte progenitor cell line CG4) are described. (author)

  17. Biomarkers for CNS involvement in pediatric lupus

    Science.gov (United States)

    Rubinstein, Tamar B; Putterman, Chaim; Goilav, Beatrice

    2015-01-01

    CNS disease, or central neuropsychiatric lupus erythematosus (cNPSLE), occurs frequently in pediatric lupus, leading to significant morbidity and poor long-term outcomes. Diagnosing cNPSLE is especially difficult in pediatrics; many current diagnostic tools are invasive and/or costly, and there are no current accepted screening mechanisms. The most complicated aspect of diagnosis is differentiating primary disease from other etiologies; research to discover new biomarkers is attempting to address this dilemma. With many mechanisms involved in the pathogenesis of cNPSLE, biomarker profiles across several modalities (molecular, psychometric and neuroimaging) will need to be used. For the care of children with lupus, the challenge will be to develop biomarkers that are accessible by noninvasive measures and reliable in a pediatric population. PMID:26079959

  18. Palmitoylethanolamide in CNS health and disease.

    Science.gov (United States)

    Mattace Raso, Giuseppina; Russo, Roberto; Calignano, Antonio; Meli, Rosaria

    2014-08-01

    The existence of acylethanolamides (AEs) in the mammalian brain has been known for decades. Among AEs, palmitoylethanolamide (PEA) is abundant in the central nervous system (CNS) and conspicuously produced by neurons and glial cells. Antihyperalgesic and neuroprotective properties of PEA have been mainly related to the reduction of neuronal firing and to control of inflammation. Growing evidence suggest that PEA may be neuroprotective during CNS neurodegenerative diseases. Advances in the understanding of the physiology and pharmacology of PEA have potentiated its interest as useful biological tool for disease management. Several rapid non-genomic and delayed genomic mechanisms of action have been identified for PEA as peroxisome proliferator-activated receptor (PPAR)-α dependent. First, an early molecular control, through Ca(+2)-activated intermediate- and/or big-conductance K(+) channels opening, drives to rapid neuronal hyperpolarization. This is reinforced by the increase of the inward Cl(-) currents due to the modulation of the gamma aminobutyric acid A receptor and by the desensitization of the transient receptor potential channel type V1. Moreover, the gene transcription-mediated mechanism sustains the long-term anti-inflammatory effects, by reducing pro-inflammatory enzyme expression and increasing neurosteroid synthesis. Overall, the integration of these different modes of action allows PEA to exert an immediate and prolonged efficacious control in neuron signaling either on inflammatory process or neuronal excitability, maintaining cellular homeostasis. In this review, we will discuss the effect of PEA on metabolism, behavior, inflammation and pain perception, related to the control of central functions and the emerging evidence demonstrating its therapeutic efficacy in several neurodegenerative diseases. Copyright © 2014. Published by Elsevier Ltd.

  19. Rotational spectroscopy and three-wave mixing of 4-carvomenthenol: A technical guide to measuring chirality in the microwave regime

    International Nuclear Information System (INIS)

    Shubert, V. Alvin; Schmitz, David; Medcraft, Chris; Krin, Anna; Patterson, David; Doyle, John M.; Schnell, Melanie

    2015-01-01

    We apply chirality sensitive microwave three-wave mixing to 4-carvomenthenol, a molecule previously uncharacterized with rotational spectroscopy. We measure its rotational spectrum in the 2-8.5 GHz range and observe three molecular conformers. We describe our method in detail, from the initial step of spectral acquisition and assignment to the final step of determining absolute configuration and enantiomeric excess. Combining fitted rotational constants with dipole moment components derived from quantum chemical calculations, we identify candidate three-wave mixing cycles which were further tested using a double resonance method. Initial optimization of the three-wave mixing signal is done by varying the duration of the second excitation pulse. With known transition dipole matrix elements, absolute configuration can be directly determined from a single measurement

  20. Inspection of helicopter rotor blades with the help of guided waves and "turning modes": Experimental and finite element analysis

    Science.gov (United States)

    Barnard, Daniel; Chakrapani, Sunil Kishore; Dayal, Vinay

    2013-01-01

    Modern helicopter rotor blades constructed of composite materials offer significant inspection challenges, particularly at inner structures, where geometry and differing material properties and anisotropy make placement of the probing energy difficult. This paper presents an application of Lamb waves to these structures, where mode conversion occurs at internal geometric discontinuities. These additional modes were found to successfully propagate to the targeted regions inside the rotor and back out, allowing evaluation of the structure. A finite element model was developed to simulate wave propagation and mode conversion in the structure and aid in identifying the signals received in the laboratory experiment. A good correlation between numerical and experimental results was observed.

  1. Guided Wave Propagation in a Gold Electrode Film on a Pb(Mg1/3Nb2/3)O3−33%PbTiO3 Ferroelectric Single Crystal Substrate

    International Nuclear Information System (INIS)

    Huang Nai-Xing; LÜ Tian-Quan; Zhang Rui; Wang Yu-Ling; Cao Wen-Wu

    2014-01-01

    Dispersion relations of Love mode acoustic guided waves propagation in Pb(Mg 1/3 Nb 2/3 )O 3 −33%PbTiO 3 (PMN-0.33 PT) single crystal with a gold electrode film are calculated. There is no cross coupling among Love wave modes, which is conducive to eliminating the cross interference between modes. The general formula is derived to precisely measure the thickness of the electrode. More acoustic energy would be concentrated inside the electrode with the increase of film thickness for a given frequency. Compared with the PZT-5 ceramic, [001] c poled PMN-33%PT single crystal has a slower attenuation of the amplitude of the acoustic guided wave. Therefore, single crystal is extremely suitable for making low loss acoustic wave devices with a high operating frequency

  2. New Brain Tumor Entities Emerge from Molecular Classification of CNS-PNETs

    DEFF Research Database (Denmark)

    Sturm, Dominik; Orr, Brent A; Toprak, Umut H

    2016-01-01

    with a recurrent genetic alteration and distinct histopathological and clinical features. These new molecular entities, designated "CNS neuroblastoma with FOXR2 activation (CNS NB-FOXR2)," "CNS Ewing sarcoma family tumor with CIC alteration (CNS EFT-CIC)," "CNS high-grade neuroepithelial tumor with MN1 alteration...

  3. A philosophy for CNS radiotracer design.

    Science.gov (United States)

    Van de Bittner, Genevieve C; Ricq, Emily L; Hooker, Jacob M

    2014-10-21

    Decades after its discovery, positron emission tomography (PET) remains the premier tool for imaging neurochemistry in living humans. Technological improvements in radiolabeling methods, camera design, and image analysis have kept PET in the forefront. In addition, the use of PET imaging has expanded because researchers have developed new radiotracers that visualize receptors, transporters, enzymes, and other molecular targets within the human brain. However, of the thousands of proteins in the central nervous system (CNS), researchers have successfully imaged fewer than 40 human proteins. To address the critical need for new radiotracers, this Account expounds on the decisions, strategies, and pitfalls of CNS radiotracer development based on our current experience in this area. We discuss the five key components of radiotracer development for human imaging: choosing a biomedical question, selection of a biological target, design of the radiotracer chemical structure, evaluation of candidate radiotracers, and analysis of preclinical imaging. It is particularly important to analyze the market of scientists or companies who might use a new radiotracer and carefully select a relevant biomedical question(s) for that audience. In the selection of a specific biological target, we emphasize how target localization and identity can constrain this process and discuss the optimal target density and affinity ratios needed for binding-based radiotracers. In addition, we discuss various PET test-retest variability requirements for monitoring changes in density, occupancy, or functionality for new radiotracers. In the synthesis of new radiotracer structures, high-throughput, modular syntheses have proved valuable, and these processes provide compounds with sites for late-stage radioisotope installation. As a result, researchers can manage the time constraints associated with the limited half-lives of isotopes. In order to evaluate brain uptake, a number of methods are available

  4. High-Frequency Guided Wave Scattering by a Partly Through-Thickness Hole Based on 3D Theory

    International Nuclear Information System (INIS)

    Zhang Hai-Yan; Xu Jian; Ma Shi-Wei

    2015-01-01

    We present a theoretical investigation of the scattering of high frequency S0 Lamb mode from a circular blind hole defect in a plate based on the 3D theory. The S0 wave is incident at the frequency above the A1 mode cut-off frequency, in which the popular approximate plate theories are inapplicable. Due to the non-symmetric blind hole defect, the scattered fields will contain higher order converted modes in addition to the fundamental S0 and A0 modes. The far-field scattering amplitudes of various propagating Lamb modes for different hole sizes are inspected. The results are compared with those of lower frequencies and some different phenomena are found. Two-dimensional Fourier transform (2DFT) results of transient scattered Lamb and SH wave signals agree well with the analytical dispersion curves, which check the validity of the solutions from another point of view. (paper)

  5. Simultaneous versus Sequential Accelerated Corneal Collagen Cross-Linking and Wave Front Guided PRK for Treatment of Keratoconus: Objective and Subjective Evaluation.

    Science.gov (United States)

    Abou Samra, Waleed Ali; El Emam, Dalia Sabry; Farag, Rania Kamel; Abouelkheir, Hossam Youssef

    2016-01-01

    Aim . To compare objective and subjective outcome after simultaneous wave front guided (WFG) PRK and accelerated corneal cross-linking (CXL) in patients with progressive keratoconus versus sequential WFG PRK 6 months after CXL. Methods . 62 eyes with progressive keratoconus were divided into two groups; the first including 30 eyes underwent simultaneous WFG PRK with accelerated CXL. The second including 32 eyes underwent subsequent WFG PRK performed 6 months later after accelerated CXL. Visual, refractive, topographic, and aberrometric data were determined preoperatively and during 1-year follow-up period and the results compared in between the 2 studied groups. Results . All evaluated visual, refractive, and aberrometric parameters demonstrated highly significant improvement in both studied groups (all P PRK and accelerated CXL is an effective and safe option to improve the vision in mild to moderate keratoconus. In one-year follow-up, there is no statistically significant difference between the simultaneous and sequential procedure.

  6. Investigation on the use of artificial neural networks to overcome the effects of environmental and operational changes on guided waves monitoring

    Science.gov (United States)

    El Mountassir, M.; Yaacoubi, S.; Dahmene, F.

    2015-07-01

    Intelligent feature extraction and advanced signal processing techniques are necessary for a better interpretation of ultrasonic guided waves signals either in structural health monitoring (SHM) or in nondestructive testing (NDT). Such signals are characterized by at least multi-modal and dispersive components. In addition, in SHM, these signals are closely vulnerable to environmental and operational conditions (EOCs), and can be severely affected. In this paper we investigate the use of Artificial Neural Network (ANN) to overcome these effects and to provide a reliable damage detection method with a minimal of false indications. An experimental case of study (full scale pipe) is presented. Damages sizes have been increased and their shapes modified in different steps. Various parameters such as the number of inputs and the number of hidden neurons were studied to find the optimal configuration of the neural network.

  7. Damage Detection Based on Power Dissipation Measured with PZT Sensors through the Combination of Electro-Mechanical Impedances and Guided Waves.

    Science.gov (United States)

    Sevillano, Enrique; Sun, Rui; Perera, Ricardo

    2016-05-05

    The use of piezoelectric ceramic transducers (such as Lead-Zirconate-Titanate-PZT) has become more and more widespread for Structural Health Monitoring (SHM) applications. Among all the techniques that are based on this smart sensing solution, guided waves and electro-mechanical impedance techniques have found wider acceptance, and so more studies and experimental works can be found containing these applications. However, even though these two techniques can be considered as complementary to each other, little work can be found focused on the combination of them in order to define a new and integrated damage detection procedure. In this work, this combination of techniques has been studied by proposing a new integrated damage indicator based on Electro-Mechanical Power Dissipation (EMPD). The applicability of this proposed technique has been tested through different experimental tests, with both lab-scale and real-scale structures.

  8. Optimization of dipeptidic inhibitors of cathepsin L for improved Toxoplasma gondii selectivity and CNS permeability.

    Science.gov (United States)

    Zwicker, Jeffery D; Diaz, Nicolas A; Guerra, Alfredo J; Kirchhoff, Paul D; Wen, Bo; Sun, Duxin; Carruthers, Vern B; Larsen, Scott D

    2018-06-01

    The neurotropic protozoan Toxoplasma gondii is the second leading cause of death due to foodborne illness in the US, and has been designated as one of five neglected parasitic infections by the Center for Disease Control and Prevention. Currently, no treatment options exist for the chronic dormant-phase Toxoplasma infection in the central nervous system (CNS). T. gondii cathepsin L (TgCPL) has recently been implicated as a novel viable target for the treatment of chronic toxoplasmosis. In this study, we report the first body of SAR work aimed at developing potent inhibitors of TgCPL with selectivity vs the human cathepsin L. Starting from a known inhibitor of human cathepsin L, and guided by structure-based design, we were able to modulate the selectivity for Toxoplasma vs human CPL by nearly 50-fold while modifying physiochemical properties to be more favorable for metabolic stability and CNS penetrance. The overall potency of our inhibitors towards TgCPL was improved from 2 μM to as low as 110 nM and we successfully demonstrated that an optimized analog 18b is capable of crossing the BBB (0.5 brain/plasma). This work is an important first step toward development of a CNS-penetrant probe to validate TgCPL as a feasible target for the treatment of chronic toxoplasmosis. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Fifth CNS international steam generator conference

    International Nuclear Information System (INIS)

    2006-01-01

    The Fifth CNS International Steam Generator Conference was held on November 26-29, 2006 in Toronto, Ontario, Canada. In contrast with other conferences which focus on specific aspects, this conference provided a wide ranging forum on nuclear steam generator technology from life-cycle management to inspection and maintenance, functional and structural performance characteristics to design architecture. The 5th conference has adopted the theme: 'Management of Real-Life Equipment Conditions and Solutions for the Future'. This theme is appropriate at a time of transition in the industry when plants are looking to optimize the performance of existing assets, prevent costly degradation and unavailability, while looking ahead for new steam generator investments in life-extension, replacements and new-build. More than 50 technical papers were presented in sessions that gave an insight to the scope: life management strategies; fouling, cleaning and chemistry; replacement strategies and new build design; materials degradation; condition assessment/fitness for service; inspection advancements and experience; and thermal hydraulic performance

  10. A Signal Decomposition Method for Ultrasonic Guided Wave Generated from Debonding Combining Smoothed Pseudo Wigner-Ville Distribution and Vold–Kalman Filter Order Tracking

    Directory of Open Access Journals (Sweden)

    Junhua Wu

    2017-01-01

    Full Text Available Carbon fibre composites have a promising application future of the vehicle, due to its excellent physical properties. Debonding is a major defect of the material. Analyses of wave packets are critical for identification of the defect on ultrasonic nondestructive evaluation and testing. In order to isolate different components of ultrasonic guided waves (GWs, a signal decomposition algorithm combining Smoothed Pseudo Wigner-Ville distribution and Vold–Kalman filter order tracking is presented. In the algorithm, the time-frequency distribution of GW is first obtained by using Smoothed Pseudo Wigner-Ville distribution. The frequencies of different modes are computed based on summation of the time-frequency coefficients in the frequency direction. On the basis of these frequencies, isolation of different modes is done by Vold–Kalman filter order tracking. The results of the simulation signal and the experimental signal reveal that the presented algorithm succeeds in decomposing the multicomponent signal into monocomponents. Even though components overlap in corresponding Fourier spectrum, they can be isolated by using the presented algorithm. So the frequency resolution of the presented method is promising. Based on this, we can do research about defect identification, calculation of the defect size, and locating the position of the defect.

  11. Analysis of perfusion weighted image of CNS lymphoma

    International Nuclear Information System (INIS)

    Lee, In Ho; Kim, Sung Tae; Kim, Hyung-Jin; Kim, Keon Ha; Jeon, Pyoung; Byun, Hong Sik

    2010-01-01

    Purpose: It is difficult to differentiate CNS lymphoma from other tumors such as malignant gliomas, metastases, or meningiomas with conventional MR imaging, because the imaging findings are overlapped between these tumors. The purpose of this study is to investigate the perfusion weighted MR imaging findings of CNS lymphomas and to compare the relative cerebral blood volume ratios between CNS lymphomas and other tumors such as high grade gliomas, metastases, or meningiomas. Materials and methods: We retrospectively reviewed MRI findings and clinical records in 13 patients with pathologically proven CNS lymphoma between January 2006 and November 2008. We evaluated the relative cerebral blood volume ratios of tumor, which were obtained by dividing the values obtained from the normal white matter on MRI. Results: Total 13 patients (M:F = 8:5; age range 46-67 years, mean age 52.3 years) were included. The CNS lymphomas showed relatively low values of maximum relative CBV ratio in most patients regardless of primary or secondary CNS lymphoma. Conclusion: Perfusion weighted image may be helpful in the diagnosis of CNS lymphoma in spite of primary or secondary or B cell or T cell.

  12. Amides from Piper capense with CNS activity

    DEFF Research Database (Denmark)

    Pedersen, Mikael Egebjerg; Metzler, Bjørn; Stafford, Gary Ivan

    2009-01-01

    Piper capense L.f. (Piperaceae) is used traditionally in South Africa as a sleep inducing remedy. Bioassay-guided fractionation of the roots of P. capense led to the isolation of piperine (1) and 4,5-dihydropiperine (2), which showed moderate affinity for the benzodiazepine site on the GABA...

  13. 3rd ENRI International Workshop on ATM/CNS

    CERN Document Server

    2014-01-01

    The Electronic Navigation Research Institute (ENRI) held its third International Workshop on ATM / CNS in 2013 with the theme of "Drafting the future sky". There is worldwide activity taking place in the research and development of modern air traffic management (ATM) and its enabling technologies in Communication, Navigation and Surveillance (CNS). Pioneering work is necessary to contribute to the global harmonization of air traffic management and control. At this workshop, leading experts in  research, industry and academia from around the world met to share their ideas and approaches on ATM/CNS related topics.

  14. Autoimmune process in CNS under Cs-137 inner irradiation

    International Nuclear Information System (INIS)

    Lisyany, N.I.; Liubich, L.D.

    1996-01-01

    Autoimmune hypothesis as to the development of radiation-induced brain injuries stands high among the concepts of the CNS post-radiation damage pathogenesis. To study the changes occurring in a living organism affected by a small-dose radiation due to incorporated radionuclides as well as to create adequate models are of critical importance in the post-Chernobyl period. The effects of chronic small-dose inner radiation on the development of autoimmune responses were evaluated by determining the level of the CNS proteins and protein-induced antibodies to the CNS components. (author)

  15. Convulsant bicuculline modifies CNS muscarinic receptor affinity

    Directory of Open Access Journals (Sweden)

    Rodríguez de Lores Arnaiz Georgina

    2006-04-01

    Full Text Available Abstract Background Previous work from this laboratory has shown that the administration of the convulsant drug 3-mercaptopropionic acid (MP, a GAD inhibitor, modifies not only GABA synthesis but also binding of the antagonist [3H]-quinuclidinyl benzilate ([3H]-QNB to central muscarinic receptors, an effect due to an increase in affinity without modifications in binding site number. The cholinergic system has been implicated in several experimental epilepsy models and the ability of acetylcholine to regulate neuronal excitability in the neocortex is well known. To study the potential relationship between GABAergic and cholinergic systems with seizure activity, we analyzed the muscarinic receptor after inducing seizure by bicuculline (BIC, known to antagonize the GABA-A postsynaptic receptor subtype. Results We analyzed binding of muscarinic antagonist [3H]-QNB to rat CNS membranes after i.p. administration of BIC at subconvulsant (1.0 mg/kg and convulsant (7.5 mg/kg doses. Subconvulsant BIC dose failed to develop seizures but produced binding alteration in the cerebellum and hippocampus with roughly 40% increase and 10% decrease, respectively. After convulsant BIC dose, which invariably led to generalized tonic-clonic seizures, binding increased 36% and 15% to cerebellar and striatal membranes respectively, but decreased 12% to hippocampal membranes. Kd value was accordingly modified: with the subconvulsant dose it decreased 27% in cerebellum whereas it increased 61% in hippocampus; with the convulsant dose, Kd value decreased 33% in cerebellum but increased 85% in hippocampus. No change in receptor number site was found, and Hill number was invariably close to unity. Conclusion Results indicate dissimilar central nervous system area susceptibility of muscarinic receptor to BIC. Ligand binding was modified not only by a convulsant BIC dose but also by a subconvulsant dose, indicating that changes are not attributable to the seizure process

  16. Air pollution: mechanisms of neuroinflammation and CNS disease.

    Science.gov (United States)

    Block, Michelle L; Calderón-Garcidueñas, Lilian

    2009-09-01

    Air pollution has been implicated as a chronic source of neuroinflammation and reactive oxygen species (ROS) that produce neuropathology and central nervous system (CNS) disease. Stroke incidence and Alzheimer's and Parkinson's disease pathology are linked to air pollution. Recent reports reveal that air pollution components reach the brain; systemic effects that impact lung and cardiovascular disease also impinge upon CNS health. While mechanisms driving air pollution-induced CNS pathology are poorly understood, new evidence suggests that microglial activation and changes in the blood-brain barrier are key components. Here we summarize recent findings detailing the mechanisms through which air pollution reaches the brain and activates the resident innate immune response to become a chronic source of pro-inflammatory factors and ROS, culminating in CNS disease.

  17. A map of taste neuron projections in the Drosophila CNS

    Indian Academy of Sciences (India)

    2014-07-08

    Jul 8, 2014 ... information that they represent. The extensive ... physiology and behaviour in the wild type and in these mutants .... taste information is processed in the CNS. 2. ..... gene affecting the specificity of the chemosensory neurons of.

  18. Pharmacokinetic, Pharmacogenetic, and Other Factors Influencing CNS Penetration of Antiretrovirals

    Directory of Open Access Journals (Sweden)

    Jacinta Nwamaka Nwogu

    2016-01-01

    Full Text Available Neurological complications associated with the human immunodeficiency virus (HIV are a matter of great concern. While antiretroviral (ARV drugs are the cornerstone of HIV treatment and typically produce neurological benefit, some ARV drugs have limited CNS penetration while others have been associated with neurotoxicity. CNS penetration is a function of several factors including sieving role of blood-brain and blood-CSF barriers and activity of innate drug transporters. Other factors are related to pharmacokinetics and pharmacogenetics of the specific ARV agent or mediated by drug interactions, local inflammation, and blood flow. In this review, we provide an overview of the various factors influencing CNS penetration of ARV drugs with an emphasis on those commonly used in sub-Saharan Africa. We also summarize some key associations between ARV drug penetration, CNS efficacy, and neurotoxicity.

  19. CNS Involvement in AML Patient Treated with 5-Azacytidine

    Directory of Open Access Journals (Sweden)

    Diamantina Vasilatou

    2014-01-01

    Full Text Available Central nervous system (CNS involvement in acute myeloid leukemia (AML is a rare complication of the disease and is associated with poor prognosis. Sometimes the clinical presentation can be unspecific and the diagnosis can be very challenging. Here we report a case of CNS infiltration in a patient suffering from AML who presented with normal complete blood count and altered mental status.

  20. CNS-directed gene therapy for lysosomal storage diseases

    OpenAIRE

    Sands, Mark S; Haskins, Mark E

    2008-01-01

    Lysosomal storage diseases (LSDs) are a group of inherited metabolic disorders usually caused by deficient activity of a single lysosomal enzyme. As most lysosomal enzymes are ubiquitously expressed, a deficiency in a single enzyme can affect multiple organ systems, including the central nervous system (CNS). At least 75% of all LSDs have a significant CNS component. Approaches such as bone marrow transplantation (BMT) or enzyme replacement therapy (ERT) can effectively treat the systemic dis...

  1. Sleep disorders in children after treatment for a CNS tumour.

    Science.gov (United States)

    Verberne, Lisa M; Maurice-Stam, Heleen; Grootenhuis, Martha A; Van Santen, Hanneke M; Schouten-Van Meeteren, Antoinette Y N

    2012-08-01

    The long-term survival of children with a central nervous system (CNS) tumour is improving. However, they experience late effects, including altered habits and patterns of sleep. We evaluated the presence and type of sleep disorders and daytime sleepiness in these children, and its associations with clinical characteristics and daily performance (fatigue and psychosocial functioning). In a cross-sectional study at the outpatient clinic of the Emma Children's Hospital AMC (February-June 2010), sleep, fatigue and psychosocial functioning were analysed in 31 CNS tumour patients (mean age: 11.8years; 20 boys) and compared with 78 patients treated for a non-CNS malignancy (mean age: 9.7years; 41 boys) and norm data. Questionnaires applied were the Sleep Disorder Scale for Children, the Epworth Sleepiness Scale, the Pediatric Quality of Life Inventory, and the Strengths and Difficulties Questionnaire. Sleeping habits and endocrine deficiencies were assessed with a self-developed questionnaire. Increased somnolence was found in CNS tumour patients compared with those with a non-CNS malignancy (8.8±2.8 versus 7.5±2.7; Psleep. No specific risk factors were identified for a sleep disorder in CNS tumour patients, but their excessive somnolence was correlated with lower fatigue related quality of life (QoL) (r=-0.78, Psleep quality and diminish fatigue. © 2011 European Sleep Research Society.

  2. Instantaneous Wave-Free Ratio versus Fractional Flow Reserve guided intervention (iFR-SWEDEHEART): Rationale and design of a multicenter, prospective, registry-based randomized clinical trial.

    Science.gov (United States)

    Götberg, Matthias; Christiansen, Evald H; Gudmundsdottir, Ingibjörg; Sandhall, Lennart; Omerovic, Elmir; James, Stefan K; Erlinge, David; Fröbert, Ole

    2015-11-01

    Instantaneous wave-free ratio (iFR) is a new hemodynamic resting index for assessment of coronary artery stenosis severity. iFR uses high frequency sampling to calculate a gradient across a coronary lesion during a period of diastole. The index has been tested against fractional flow reserve (FFR) and found to have an overall classification agreement of 80% to 85%. Whether the level of disagreement is clinically relevant is unknown. Clinical outcome data on iFR are scarce. This study is a registry-based randomized clinical trial, which is a novel strategy using health quality registries as on-line platforms for randomization, case record forms, and follow-up. iFR-SWEDEHEART is a multicenter, prospective, randomized, controlled, clinical open-label clinical trial. Two thousand patients with stable angina or acute coronary syndrome and an indication for physiology-guided assessment of one or more coronary stenoses will be randomized 1:1 to either iFR- or FFR-guided intervention. The randomization will be conducted online in the Swedish web-based system for enhancement and development of evidence-based care in heart disease evaluated according to recommended therapies (SWEDEHEART) registry. The trial has a non-inferiority design, with a primary combined end point of all-cause death, non-fatal myocardial infarction, and unplanned revascularization at 12 months. End points will be identified through national registries and undergo central blind adjudication to ensure data quality. The iFR-SWEDEHEART trial is an registry-based randomized clinical trial evaluating the safety and efficacy of the diagnostic method iFR compared to FFR. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Utility of FDG-PETCT and magnetic resonance spectroscopy in differentiating between cerebral lymphoma and non-malignant CNS lesions in HIV-infected patients

    Energy Technology Data Exchange (ETDEWEB)

    Westwood, Thomas D., E-mail: tdwestwood@googlemail.com [Department of Radiology, The Christie NHS Foundation Trust, Wilmslow Road, Manchester (United Kingdom); Hogan, Celia, E-mail: celiahogan@hotmail.com [Monsall Unit, Department of Infectious Diseases and Tropical Medicine, North Manchester General Hospital, Pennine Acute Hospitals NHS Trust (United Kingdom); Julyan, Peter J., E-mail: Peter.Julyan@christie.nhs.uk [Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Wilmslow Road, Manchester (United Kingdom); Coutts, Glyn, E-mail: Glyn.Coutts@christie.nhs.uk [Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Wilmslow Road, Manchester (United Kingdom); Bonington, Suzie, E-mail: suzi.bonington@christie.nhs.uk [Department of Radiology, The Christie NHS Foundation Trust, Wilmslow Road, Manchester (United Kingdom); Carrington, Bernadette, E-mail: Bernadette.Carrington@christie.nhs.uk [Department of Radiology, The Christie NHS Foundation Trust, Wilmslow Road, Manchester (United Kingdom); Taylor, Ben, E-mail: Ben.taylor@christie.nhs.uk [Department of Radiology, The Christie NHS Foundation Trust, Wilmslow Road, Manchester (United Kingdom); Khoo, Saye, E-mail: S.H.Khoo@liverpool.ac.uk [Department of Infectious Diseases and Tropical Medicine, Royal Liverpool Hospital, Liverpool (United Kingdom); Bonington, Alec, E-mail: Alec.Bonington@pat.nhs.uk [Monsall Unit, Department of Infectious Diseases and Tropical Medicine, North Manchester General Hospital, Pennine Acute Hospitals NHS Trust (United Kingdom)

    2013-08-15

    Background and purpose: In HIV infected patients, MRI cannot reliably differentiate between central nervous system (CNS) lymphoma and non-malignant CNS lesions, particularly cerebral toxoplasmosis (CTOX). This study prospectively investigates the utility of FDG PET-CT and magnetic resonance spectroscopy (MRS) in discriminating CNS lymphoma from non-malignant CNS lesions in HIV infected patients, and assesses the ability of FDG PET-CT to guide the use of early brain biopsy. Methods: 10 HIV patients with neurological symptoms and contrast enhancing lesions on MRI were commenced on anti-toxoplasmosis therapy before undergoing FDG PET-CT and MRS. Brain biopsies were sought in those with FDG PET-CT suggestive of CNS lymphoma, and in those with a negative FDG PET-CT scan who failed to respond to therapy. Final diagnosis was based on histology or treatment response. Results: Two patients were confirmed to have CNS lymphoma and FDG PET-CT was consistent with this diagnosis in both. Six patients had cerebral toxoplasmosis in all of whom FDG PET-CT was consistent with non-malignant disease. One patient had progressive multifocal leukoencephalopathy (PML), FDG PET-CT was equivocal. One patient had a haemorrhagic brain metastasis and FDG PET-CT wrongly suggested non-malignant disease. MRS was performed successfully in eight subjects: three results were suggestive of CNS lymphoma (one true positive, two false positive), four suggested CTOX (two false negative, two true negative), one scan was equivocal. Conclusion: FDG PET-CT correctly identified all cases of CNS lymphoma and CTOX, supporting its use in this situation. MRS was unhelpful in our cohort.

  4. Utility of FDG-PETCT and magnetic resonance spectroscopy in differentiating between cerebral lymphoma and non-malignant CNS lesions in HIV-infected patients

    International Nuclear Information System (INIS)

    Westwood, Thomas D.; Hogan, Celia; Julyan, Peter J.; Coutts, Glyn; Bonington, Suzie; Carrington, Bernadette; Taylor, Ben; Khoo, Saye; Bonington, Alec

    2013-01-01

    Background and purpose: In HIV infected patients, MRI cannot reliably differentiate between central nervous system (CNS) lymphoma and non-malignant CNS lesions, particularly cerebral toxoplasmosis (CTOX). This study prospectively investigates the utility of FDG PET-CT and magnetic resonance spectroscopy (MRS) in discriminating CNS lymphoma from non-malignant CNS lesions in HIV infected patients, and assesses the ability of FDG PET-CT to guide the use of early brain biopsy. Methods: 10 HIV patients with neurological symptoms and contrast enhancing lesions on MRI were commenced on anti-toxoplasmosis therapy before undergoing FDG PET-CT and MRS. Brain biopsies were sought in those with FDG PET-CT suggestive of CNS lymphoma, and in those with a negative FDG PET-CT scan who failed to respond to therapy. Final diagnosis was based on histology or treatment response. Results: Two patients were confirmed to have CNS lymphoma and FDG PET-CT was consistent with this diagnosis in both. Six patients had cerebral toxoplasmosis in all of whom FDG PET-CT was consistent with non-malignant disease. One patient had progressive multifocal leukoencephalopathy (PML), FDG PET-CT was equivocal. One patient had a haemorrhagic brain metastasis and FDG PET-CT wrongly suggested non-malignant disease. MRS was performed successfully in eight subjects: three results were suggestive of CNS lymphoma (one true positive, two false positive), four suggested CTOX (two false negative, two true negative), one scan was equivocal. Conclusion: FDG PET-CT correctly identified all cases of CNS lymphoma and CTOX, supporting its use in this situation. MRS was unhelpful in our cohort

  5. Simultaneous versus Sequential Accelerated Corneal Collagen Cross-Linking and Wave Front Guided PRK for Treatment of Keratoconus: Objective and Subjective Evaluation

    Directory of Open Access Journals (Sweden)

    Waleed Ali Abou Samra

    2016-01-01

    Full Text Available Aim. To compare objective and subjective outcome after simultaneous wave front guided (WFG PRK and accelerated corneal cross-linking (CXL in patients with progressive keratoconus versus sequential WFG PRK 6 months after CXL. Methods. 62 eyes with progressive keratoconus were divided into two groups; the first including 30 eyes underwent simultaneous WFG PRK with accelerated CXL. The second including 32 eyes underwent subsequent WFG PRK performed 6 months later after accelerated CXL. Visual, refractive, topographic, and aberrometric data were determined preoperatively and during 1-year follow-up period and the results compared in between the 2 studied groups. Results. All evaluated visual, refractive, and aberrometric parameters demonstrated highly significant improvement in both studied groups (all P<0.001. A significant improvement was observed in keratometric and Q values. The improvement in all parameters was stable till the end of follow-up. Likewise, no significant difference was determined in between the 2 groups in any of recorded parameters. Subjective data revealed similarly significant improvement in both groups. Conclusions. WFG PRK and accelerated CXL is an effective and safe option to improve the vision in mild to moderate keratoconus. In one-year follow-up, there is no statistically significant difference between the simultaneous and sequential procedure.

  6. Mode and polarization state selected guided wave spectroscopy of orientational anisotrophy in model membrane cellulosic polymer films: relevance to lab-on-a-chip

    Science.gov (United States)

    Andrews, Mark P.; Kanigan, Tanya

    2007-06-01

    Orientation anisotropies in structural properties relevant to the use of cellulosic polymers as membranes for lab-on-chips were investigated for cellulose acetate (CA) and regenerated cellulose (RC) films deposited as slab waveguides. Anisotropy was probed with mode and polarization state selected guided wave Raman spectroscopy. CA exhibits partial chain orientation in the plane of the film, and this orientation is independent of sample substrate and film preparation conditions. RC films also show in-plane anisotropy, where the hexose sugar rings lie roughly in the plane of the film. Explanations are given of the role of artifacts in interpreting waveguide Raman spectra, including anomalous contributions to Raman spectra that arise from deviations from right angle scattering geometry, mode-dependent contributions to longitudinal electric field components and TETM mode conversion. We explore diffusion profiles of small molecules in cellulosic films by adaptations of an inverse-Wentzel-Kramers-Brillouin (iWKB) recursive, noninteger virtual mode index algorithm. Perturbations in the refractive index distribution, n(z), are recovered from the measured relative propagation constants, neffective,m, of the planar waveguide. The refractive index distribution then yields the diffusion profile.

  7. Actuarial risk of isolated CNS involvement in Ewing's sarcoma following prophylactic cranial irradiation and intrathecal methotrexate

    International Nuclear Information System (INIS)

    Trigg, M.E.; Makuch, R.; Glaubiger, D.

    1985-01-01

    Records of 154 patients with Ewing's sarcoma treated at the National Cancer Institute were reviewed to assess the incidence and risk of developing isolated central nervous system (CNS) Ewing's sarcoma. Sixty-two of the 154 patients had received CNS irradiation and intrathecal (i.t.) methotrexate as part of their initial therapy to prevent the occurrence of isolated CNS Ewing's sarcoma. The risk of developing isolate CNS Ewing's sarcoma was greatest within the first two years after diagnosis and was approximately 10%. The overall risk of CNS recurrence in the group of patients receiving DNS treatment was similar to the group receiving no therapy directed to the CNS. The occurrence of isolated CNS involvement was not prevented by the use of CNS irradiation and i.t. methotrexate. Because of a lack of efficacy to the CNS irradiation regimen, current treatment regimens do not include therapy directed to CNS

  8. Bovine-associated CNS species resist phagocytosis differently

    Science.gov (United States)

    2013-01-01

    Background Coagulase-negative staphylococci (CNS) cause usually subclinical or mild clinical bovine mastitis, which often remains persistent. Symptoms are usually mild, mostly only comprising slight changes in the appearance of milk and possibly slight swelling. However, clinical mastitis with severe signs has also been reported. The reasons for the differences in clinical expression are largely unknown. Macrophages play an important role in the innate immunity of the udder. This study examined phagocytosis and killing by mouse macrophage cells of three CNS species: Staphylococcus chromogenes (15 isolates), Staphylococcus agnetis (6 isolates) and Staphylococcus simulans (15 isolates). Staphylococcus aureus (7 isolates) was also included as a control. Results All the studied CNS species were phagocytosed by macrophages, but S. simulans resisted phagocytosis more effectively than the other CNS species. Only S. chromogenes was substantially killed by macrophages. Significant variations between isolates were seen in both phagocytosis and killing by macrophages and were more common in the killing assays. Significant differences between single CNS species and S. aureus were observed in both assays. Conclusion This study demonstrated that differences in the phagocytosis and killing of mastitis-causing staphylococci by macrophages exist at both the species and isolate level. PMID:24207012

  9. Guide device

    International Nuclear Information System (INIS)

    Brammer, C.M. Jr.

    1977-01-01

    Disclosed is a fuel handling guide tube centering device for use in nuclear reactors during fuel assembly handling operations. The device comprises an outer ring secured to the flange of a nuclear reactor pressure vessel, a rotatable table rotatably coupled to the outer ring, and a plurality of openings through the table. Truncated locating cones are positioned in each of the openings in the table, and the locating cones center the guide tube during fuel handling operations. The openings in the table are located such that each fuel assembly in the nuclear core may be aligned with one of the openings by a suitable rotation of the table. The locating cones thereby provide alignment between the fuel handling mechanism located in the guide tube and the individual fuel assemblies of the cone. The need for a device to provide alignment is especially critical for floating nuclear power plants, where wave motion may exist during fuel handling operations. 5 claims, 4 figures

  10. Real-time Cure Monitoring of Composites Using a Guided wave-based System with High Temperature Piezoelectric Transducers, Fiber Bragg Gratings, and Phase-shifted Fiber Bragg Gratings

    Science.gov (United States)

    Hudson, Tyler Blake

    An in-process, in-situ cure monitoring technique utilizing a guided wave-based concept for carbon fiber reinforced polymer (CFRP) composites was investigated. Two automated cure monitoring systems using guided-wave ultrasonics were developed for characterizing the state of the cure. In the first system, surface mounted high-temperature piezoelectric transducer arrays were employed for actuation and sensing. The second system motivated by the success of the first system includes a single piezoelectric disc, bonded onto the surface of the composite for excitation; fiber Bragg gratings (FBGs) and/or phase-shifted fiber Bragg gratings (PSFBGs) were embedded in the composite for distributed cure sensing. Composite material properties (viscosity and degree of cure) evolved during cure of the panels fabricated from HexcelRTM IM7/8552 prepreg correlated well to the amplitude, time of arrival, and group velocity of the guided wave-based measurements during the cure cycle. In addition, key phase transitions (gelation and vitrification) were clearly identified from the experimental data during the same cure cycle. The material properties and phase transitions were validated using cure process modeling software (e.g., RAVENRTM). The high-temperature piezoelectric transducer array system demonstrated the feasibility of a guided wave-based, in-process, cure monitoring and provided the framework for defect detection during cure. Ultimately, this system could provide a traceable data stream for non-compliance investigations during serial production and perform closed-loop process control to maximize composite panel quality and consistency. In addition, this system could be deployed as a "smart" caul/tool plate to existing production lines without changing the design of the aircraft/structure. With the second system, strain in low frequency (quasi-static) and the guided wavebased signals in several hundred kilohertz range were measured almost simultaneously using the same FBG or PS

  11. Pericytes Stimulate Oligodendrocyte Progenitor Cell Differentiation during CNS Remyelination

    Directory of Open Access Journals (Sweden)

    Alerie Guzman De La Fuente

    2017-08-01

    Full Text Available The role of the neurovascular niche in CNS myelin regeneration is incompletely understood. Here, we show that, upon demyelination, CNS-resident pericytes (PCs proliferate, and parenchymal non-vessel-associated PC-like cells (PLCs rapidly develop. During remyelination, mature oligodendrocytes were found in close proximity to PCs. In Pdgfbret/ret mice, which have reduced PC numbers, oligodendrocyte progenitor cell (OPC differentiation was delayed, although remyelination proceeded to completion. PC-conditioned medium accelerated and enhanced OPC differentiation in vitro and increased the rate of remyelination in an ex vivo cerebellar slice model of demyelination. We identified Lama2 as a PC-derived factor that promotes OPC differentiation. Thus, the functional role of PCs is not restricted to vascular homeostasis but includes the modulation of adult CNS progenitor cells involved in regeneration.

  12. Can injured adult CNS axons regenerate by recapitulating development?

    Science.gov (United States)

    Hilton, Brett J; Bradke, Frank

    2017-10-01

    In the adult mammalian central nervous system (CNS), neurons typically fail to regenerate their axons after injury. During development, by contrast, neurons extend axons effectively. A variety of intracellular mechanisms mediate this difference, including changes in gene expression, the ability to form a growth cone, differences in mitochondrial function/axonal transport and the efficacy of synaptic transmission. In turn, these intracellular processes are linked to extracellular differences between the developing and adult CNS. During development, the extracellular environment directs axon growth and circuit formation. In adulthood, by contrast, extracellular factors, such as myelin and the extracellular matrix, restrict axon growth. Here, we discuss whether the reactivation of developmental processes can elicit axon regeneration in the injured CNS. © 2017. Published by The Company of Biologists Ltd.

  13. Número e espaçamento entre hastes de guia de onda para medida da umidade do solo com TDR Number and spacing between wave guide rods for measurement of soil water content with TDR

    Directory of Open Access Journals (Sweden)

    Eugênio F. Coelho

    2003-08-01

    feasibility of the use of wave guides of two and three rods with different spacings. Disturbed soil samples were packed in PVC tube segments of 0.075 m diameter. Two sets of 24 have guides were constructed. One of this sets had a capacitor. In each set one half of the wave guides had two rods and the other half contained three rods. The rod spacing varied from 0.009 to 0.022 m. Soil water content data from gravimetry and soil bulk dielectric constant values from Trase System analyzer were collected during drying process with water content values ranging from 0.31 to 0.13 m³ m-3. Five mathematical models were fitted to water content and bulk dielectric constant data. The Malicki's model was the most adequate for estimating soil water content as a function of bulk dielectric constant. The wave guides with three rods 0.017 m apart from each other showed the best performance. The three-rod wave-guides without capacitor performed better for water content determination than the two-rod wave-guides without capacitor. The three-rod wave-guides without capacitor performed better than three-rod wave-guides with capacitor.

  14. Propagation of sound waves in ducts

    DEFF Research Database (Denmark)

    Jacobsen, Finn

    2000-01-01

    Plane wave propagation in ducts with rigid walls, radiation from ducts, classical four-pole theory for composite duct systems, and three-dimentional waves in wave guides of various cross-sectional shape are described.......Plane wave propagation in ducts with rigid walls, radiation from ducts, classical four-pole theory for composite duct systems, and three-dimentional waves in wave guides of various cross-sectional shape are described....

  15. Drug Elucidation: Invertebrate Genetics Sheds New Light on the Molecular Targets of CNS Drugs

    Directory of Open Access Journals (Sweden)

    Donard S. Dwyer

    2014-07-01

    Full Text Available Many important drugs approved to treat common human diseases were discovered by serendipity, without a firm understanding of their modes of action. As a result, the side effects and interactions of these medications are often unpredictable, and there is limited guidance for improving the design of next-generation drugs. Here, we review the innovative use of simple model organisms, especially Caenorhabditis elegans, to gain fresh insights into the complex biological effects of approved CNS medications. Whereas drug discovery involves the identification of new drug targets and lead compounds/biologics, and drug development spans preclinical testing to FDA approval, drug elucidation refers to the process of understanding the mechanisms of action of marketed drugs by studying their novel effects in model organisms. Drug elucidation studies have revealed new pathways affected by antipsychotic drugs, e.g., the insulin signaling pathway, a trace amine receptor and a nicotinic acetylcholine receptor. Similarly, novel targets of antidepressant drugs and lithium have been identified in C. elegans, including lipid-binding/transport proteins and the SGK-1 signaling pathway, respectively. Elucidation of the mode of action of anesthetic agents has shown that anesthesia can involve mitochondrial targets, leak currents and gap junctions. The general approach reviewed in this article has advanced our knowledge about important drugs for CNS disorders and can guide future drug discovery efforts.

  16. New Brain Tumor Entities Emerge from Molecular Classification of CNS-PNETs.

    Science.gov (United States)

    Sturm, Dominik; Orr, Brent A; Toprak, Umut H; Hovestadt, Volker; Jones, David T W; Capper, David; Sill, Martin; Buchhalter, Ivo; Northcott, Paul A; Leis, Irina; Ryzhova, Marina; Koelsche, Christian; Pfaff, Elke; Allen, Sariah J; Balasubramanian, Gnanaprakash; Worst, Barbara C; Pajtler, Kristian W; Brabetz, Sebastian; Johann, Pascal D; Sahm, Felix; Reimand, Jüri; Mackay, Alan; Carvalho, Diana M; Remke, Marc; Phillips, Joanna J; Perry, Arie; Cowdrey, Cynthia; Drissi, Rachid; Fouladi, Maryam; Giangaspero, Felice; Łastowska, Maria; Grajkowska, Wiesława; Scheurlen, Wolfram; Pietsch, Torsten; Hagel, Christian; Gojo, Johannes; Lötsch, Daniela; Berger, Walter; Slavc, Irene; Haberler, Christine; Jouvet, Anne; Holm, Stefan; Hofer, Silvia; Prinz, Marco; Keohane, Catherine; Fried, Iris; Mawrin, Christian; Scheie, David; Mobley, Bret C; Schniederjan, Matthew J; Santi, Mariarita; Buccoliero, Anna M; Dahiya, Sonika; Kramm, Christof M; von Bueren, André O; von Hoff, Katja; Rutkowski, Stefan; Herold-Mende, Christel; Frühwald, Michael C; Milde, Till; Hasselblatt, Martin; Wesseling, Pieter; Rößler, Jochen; Schüller, Ulrich; Ebinger, Martin; Schittenhelm, Jens; Frank, Stephan; Grobholz, Rainer; Vajtai, Istvan; Hans, Volkmar; Schneppenheim, Reinhard; Zitterbart, Karel; Collins, V Peter; Aronica, Eleonora; Varlet, Pascale; Puget, Stephanie; Dufour, Christelle; Grill, Jacques; Figarella-Branger, Dominique; Wolter, Marietta; Schuhmann, Martin U; Shalaby, Tarek; Grotzer, Michael; van Meter, Timothy; Monoranu, Camelia-Maria; Felsberg, Jörg; Reifenberger, Guido; Snuderl, Matija; Forrester, Lynn Ann; Koster, Jan; Versteeg, Rogier; Volckmann, Richard; van Sluis, Peter; Wolf, Stephan; Mikkelsen, Tom; Gajjar, Amar; Aldape, Kenneth; Moore, Andrew S; Taylor, Michael D; Jones, Chris; Jabado, Nada; Karajannis, Matthias A; Eils, Roland; Schlesner, Matthias; Lichter, Peter; von Deimling, Andreas; Pfister, Stefan M; Ellison, David W; Korshunov, Andrey; Kool, Marcel

    2016-02-25

    Primitive neuroectodermal tumors of the central nervous system (CNS-PNETs) are highly aggressive, poorly differentiated embryonal tumors occurring predominantly in young children but also affecting adolescents and adults. Herein, we demonstrate that a significant proportion of institutionally diagnosed CNS-PNETs display molecular profiles indistinguishable from those of various other well-defined CNS tumor entities, facilitating diagnosis and appropriate therapy for patients with these tumors. From the remaining fraction of CNS-PNETs, we identify four new CNS tumor entities, each associated with a recurrent genetic alteration and distinct histopathological and clinical features. These new molecular entities, designated "CNS neuroblastoma with FOXR2 activation (CNS NB-FOXR2)," "CNS Ewing sarcoma family tumor with CIC alteration (CNS EFT-CIC)," "CNS high-grade neuroepithelial tumor with MN1 alteration (CNS HGNET-MN1)," and "CNS high-grade neuroepithelial tumor with BCOR alteration (CNS HGNET-BCOR)," will enable meaningful clinical trials and the development of therapeutic strategies for patients affected by poorly differentiated CNS tumors. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Scalable Synthesis of Triple-Core-Shell Nanostructures of TiO2 @MnO2 @C for High Performance Supercapacitors Using Structure-Guided Combustion Waves.

    Science.gov (United States)

    Shin, Dongjoon; Shin, Jungho; Yeo, Taehan; Hwang, Hayoung; Park, Seonghyun; Choi, Wonjoon

    2018-03-01

    Core-shell nanostructures of metal oxides and carbon-based materials have emerged as outstanding electrode materials for supercapacitors and batteries. However, their synthesis requires complex procedures that incur high costs and long processing times. Herein, a new route is proposed for synthesizing triple-core-shell nanoparticles of TiO 2 @MnO 2 @C using structure-guided combustion waves (SGCWs), which originate from incomplete combustion inside chemical-fuel-wrapped nanostructures, and their application in supercapacitor electrodes. SGCWs transform TiO 2 to TiO 2 @C and TiO 2 @MnO 2 to TiO 2 @MnO 2 @C via the incompletely combusted carbonaceous fuels under an open-air atmosphere, in seconds. The synthesized carbon layers act as templates for MnO 2 shells in TiO 2 @C and organic shells of TiO 2 @MnO 2 @C. The TiO 2 @MnO 2 @C-based electrodes exhibit a greater specific capacitance (488 F g -1 at 5 mV s -1 ) and capacitance retention (97.4% after 10 000 cycles at 1.0 V s -1 ), while the absence of MnO 2 and carbon shells reveals a severe degradation in the specific capacitance and capacitance retention. Because the core-TiO 2 nanoparticles and carbon shell prevent the deformation of the inner and outer sides of the MnO 2 shell, the nanostructures of the TiO 2 @MnO 2 @C are preserved despite the long-term cycling, giving the superior performance. This SGCW-driven fabrication enables the scalable synthesis of multiple-core-shell structures applicable to diverse electrochemical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Low-Cost, Fiber-Optic Hydrogen Gas Detector Using Guided-Wave, Surface-Plasmon Resonance in Chemochromic Thin Films

    International Nuclear Information System (INIS)

    Tracy, C.E.; Benson, D.K.; Haberman, D.P.; Hishmeh, G.A.; Ciszek, P.A.

    1998-01-01

    Low-cost, hydrogen-gas-leak detectors are needed for many hydrogen applications, such as hydrogen-fueled vehicles where several detectors may be required in different locations on each vehicle. A fiber-optic leak detector could be inherently safer than conventional detectors, because it would remove all detector electronics from the vicinity of potential leaks. It would also provide freedom from electromagnetic interference, a serious problem in fuel-cell-powered electric vehicles. This paper describes the design of a fiber-optic, surface-plasmon-resonance hydrogen detector, and efforts to make it more sensitive, selective, and durable. Chemochromic materials, such as tungsten oxide and certain Lanthanide hydrides, can reversibly react with hydrogen in air while exhibiting significant changes in their optical properties. Thin films of these materials applied to a sensor at the end of an optical fiber have been used to detect low concentrations of hydrogen gas in air. The coatings include a thin silver layer in which the surface plasmon is generated, a thin film of the chemochromic material, and a catalytic layer of palladium that facilitates the reaction with hydrogen. The film thickness is chosen to produce a guided-surface plasmon wave along the interface between the silver and the chemochromic material. A dichroic beam-splitter separates the reflected spectrum into a portion near the resonance and a portion away from the resonance, and directs these two portions to two separate photodiodes. The electronic ratio of these two signals cancels most of the fiber transmission noise and provides a stable hydrogen signal

  19. Investigation of the use of uniaxial comb-shaped Galfenol patches for a guided wave-based magnetostrictive phased array sensor

    Science.gov (United States)

    Yoo, Byungseok; Pines, Darryll J.

    2018-05-01

    This paper investigates the use of uniaxial comb-shaped Fe-Ga alloy (Galfenol) patches in the development of a Magnetostrictive Phased Array Sensor (MPAS) for the Guided Wave (GW) damage inspection technique. The MPAS consists of six highly-textured Galfenol patches with a preferred orientation and a Hexagonal Magnetic Circuit Device (HMCD). The Galfenol patches individually aligned to distinct azimuthal directions were permanently attached to a thin aluminum plate specimen. The detachable HMCD encloses a biasing magnet and six sensing coils with unique directional sensing preferences, equivalent to the specific orientation of the discrete Galfenol patches. The preliminary experimental tests validated that the GW sensing performance and directional sensitivity of the Galfenol-based sensor were significantly improved by the magnetic shape anisotropy effect on the fabrication of uniaxial comb fingers to a Galfenol disc patch. We employed a series of uniaxial comb-shaped Galfenol patches to form an MPAS with a hexagonal sensor configuration, uniformly arranged within a diameter of 1". The Galfenol MPAS was utilized to identify structural damage simulated by loosening joint bolts used to fasten the plate specimen to a frame structure. We compared the damage detection results of the MPAS with those of a PZT Phased Array Sensor (PPAS) collocated to the back surface of the plate. The directional filtering characteristic of the Galfenol MPAS led to acquiring less complicated GW signals than the PPAS using omnidirectional PZT discs. However, due to the detection limit of the standard hexagonal patterned array, the two array sensors apparently identified only the loosened bolts located along one of the preferred orientations of the array configuration. The use of the fixed number of the Galfenol patches for the MPAS construction constrained the capability of sensing point multiplication of the HMCD by altering its rotational orientation, resulting in such damage detection

  20. Phantom limb pain: a case of maladaptive CNS plasticity?

    DEFF Research Database (Denmark)

    Flor, Herta; Nikolajsen, Lone; Jensen, Troels Staehelin

    2006-01-01

    might be a phenomenon of the CNS that is related to plastic changes at several levels of the neuraxis and especially the cortex. Here, we discuss the evidence for putative pathophysiological mechanisms with an emphasis on central, and in particular cortical, changes. We cite both animal and human...

  1. Neurolymphomatosis: An International Primary CNS Lymphoma Collaborative Group report

    NARCIS (Netherlands)

    S. Grisariu (Sigal); B. Avni (Batia); T.T. Batchelor (Tracy); M.J. van den Bent (Martin); F. Bokstein (Felix); D. Schiff (David); O. Kuittinen (Outi); M.C. Chamberlain (Marc C.); P. Roth (Patrick); A. Nemets (Anatoly); E. Shalom (Edna); D. Ben-Yehuda (Dina); T. Siegal (Tali)

    2010-01-01

    textabstractNeurolymphomatosis (NL) is a rare clinical entity. The International Primary CNS Lymphoma Collaborative Group retrospectively analyzed 50 patients assembled from 12 centers in 5 countries over a 16-year period. NL was related to non-Hodgkin lymphoma in 90% and to acute leukemia in 10%.

  2. Causes of CNS inflammation and potential targets for anticonvulsants.

    Science.gov (United States)

    Falip, Mercé; Salas-Puig, Xavier; Cara, Carlos

    2013-08-01

    Inflammation is one of the most important endogenous defence mechanisms in an organism. It has been suggested that inflammation plays an important role in the pathophysiology of a number of human epilepsies and convulsive disorders, and there is clinical and experimental evidence to suggest that inflammatory processes within the CNS may either contribute to or be a consequence of epileptogenesis. This review discusses evidence from human studies on the role of inflammation in epilepsy and highlights potential new targets in the inflammatory cascade for antiepileptic drugs. A number of mechanisms have been shown to be involved in CNS inflammatory reactions. These include an inflammatory response at the level of the blood-brain barrier (BBB), immune-mediated damage to the CNS, stress-induced release of inflammatory mediators and direct neuronal dysfunction or damage as a result of inflammatory reactions. Mediators of inflammation in the CNS include interleukin (IL)-1β, tumour necrosis factor-α, nuclear factor-κB and toll-like receptor-4 (TLR4). IL-1β, BBB and high-mobility group box-1-TLR4 signalling appear to be the most promising targets for anticonvulsant agents directed at inflammation. Such agents may provide effective therapy for drug-resistant epilepsies in the future.

  3. Metallothionein Expression and Roles During Neuropathology in the CNS

    DEFF Research Database (Denmark)

    Penkowa, Milena

    2006-01-01

    , their receptors and neurotrophins (TGFb, TGFb-Receptor, bFGF, bFGF-Receptor, VEGF, NT-3, NT-4/5, NGF); angiogenesis; and growth cone formation. Hence, MT-I+II enhance CNS tissue repair as seen clearly after the cryogenic injury, after which MT-I+II promote substitution of the necrotic lesion cavity with a glial...

  4. Glypicans and FGFs in CNS Development and Function

    NARCIS (Netherlands)

    Galli, Antonella

    2003-01-01

    One of the most important events during central nervous system (CNS) development is the communication between cells. Cell-to-cell signaling implicates the interaction between a signaling molecules (or ligands) and their receptors. Ligand-receptor interaction is a tightly regulated process and is

  5. Problems of prophylactic CNS radiotherapy in acute children's leukemia

    International Nuclear Information System (INIS)

    Bek, V.; Pribylova, O.; Abrahamova, J.; Hynieova, H.; Hrodek, O.

    1980-01-01

    The prophylactic treatment of the CNS was conducted by cobalt teletherapy of the cranium and by intrathecal application of MTX after the induction of primary remission in 70 children with acute leukemia throughout 5 years up to the end of 1978. The method of the combined radio- and chemoprophylaxis of the CNS was being changed during the years, especially as far as the radiation dose for the cranium was concerned. A detailed analysis made in a group of 59 children with the minimum interval of 18 months from the beginning of the treatment showed the best results after the application of a dose of 24 Gy/3 weeks. Following this procedure the relapse of leukemia in the CNS occurred in 9% only, whereas on the application of doses of 20 Gy and lower it occurred in 35 to 40%. On the whole 24 out of 59 children, i.e. 41%, are surviving, 35 children, i.e. 59%, died. Mostly complete, but only temporary, epilation was an invariable consequence of the irradiation of the cranium. The somnolence syndrome was only sporadically observed. It cannot be excluded, however, that some of its forms in patients discharged from hospital escaped attention. No case was recorded of serious impairment of the CNS of the leukoencephalopathic type. Up to now the psychomotor, intellectual and emotional development of the surviving children has been normal. (author)

  6. Sleep disorders in children after treatment for a CNS tumour

    NARCIS (Netherlands)

    Verberne, Lisa M.; Maurice-Stam, Heleen; Grootenhuis, Martha A.; van Santen, Hanneke M.; Schouten-van Meeteren, Antoinette Y. N.

    2012-01-01

    The long-term survival of children with a central nervous system (CNS) tumour is improving. However, they experience late effects, including altered habits and patterns of sleep. We evaluated the presence and type of sleep disorders and daytime sleepiness in these children, and its associations with

  7. PEG minocycline-liposomes ameliorate CNS autoimmune disease.

    Directory of Open Access Journals (Sweden)

    Wei Hu

    Full Text Available Minocycline is an oral tetracycline derivative with good bioavailability in the central nervous system (CNS. Minocycline, a potent inhibitor of matrix metalloproteinase (MMP-9, attenuates disease activity in experimental autoimmune encephalomyelitis (EAE, an animal model of multiple sclerosis (MS. Potential adverse effects associated with long-term daily minocycline therapy in human patients are concerning. Here, we investigated whether less frequent treatment with long-circulating polyethylene glycol (PEG minocycline liposomes are effective in treating EAE.Performing in vitro time kinetic studies of PEG minocycline-liposomes in human peripheral blood mononuclear cells (PBMCs, we determined that PEG minocycline-liposome preparations stabilized with CaCl(2 are effective in diminishing MMP-9 activity. Intravenous injections of PEG minocycline-liposomes every five days were as effective in ameliorating clinical EAE as daily intraperitoneal injections of minocycline. Treatment of animals with PEG minocycline-liposomes significantly reduced the number of CNS-infiltrating leukocytes, and the overall expression of MMP-9 in the CNS. There was also a significant suppression of MMP-9 expression and proteolytic activity in splenocytes of treated animals, but not in CNS-infiltrating leukocytes. Thus, leukocytes gaining access to the brain and spinal cord require the same absolute amount of MMP-9 in all treatment groups, but minocycline decreases the absolute cell number.Our data indicate that less frequent injections of PEG minocycline-liposomes are an effective alternative pharmacotherapy to daily minocycline injections for the treatment of CNS autoimmune diseases. Also, inhibition of MMP-9 remains a promising treatment target in EAE and patients with MS.

  8. Wave-guided optical waveguides

    DEFF Research Database (Denmark)

    Palima, Darwin; Bañas, Andrew Rafael; Vizsnyiczai, George

    2012-01-01

    This work primarily aims to fabricate and use two photon polymerization (2PP) microstructures capable of being optically manipulated into any arbitrary orientation. We have integrated optical waveguides into the structures and therefore have freestanding waveguides, which can be positioned anywhe...... bridge the diffraction barrier. This structure-mediated paradigm may be carried forward to open new possibilities for exploiting beams from far-field optics down to the subwavelength domain....

  9. CARR-CNS with crescent-shape moderator cell and sub-cooling helium jacket around cell

    International Nuclear Information System (INIS)

    Yu, Qingfeng; Feng, Quanke; Kawai, Takeshi; Cheng, Liang; Shen, Feng; Yuan, Luzheng

    2005-01-01

    The new type of the moderator cell was developed for the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR) which is now constructing at the China Institute of Atomic Energy in Beijing. A crescent-shape moderator cell covered by the sub-cooling helium jacket is adopted. A crescent-shape would help to increase the volume of the moderator cell for corresponding it to the 4 cold neutron guide tubes, even if liquid hydrogen not liquid deuterium were used as a cold moderator. The sub-cooling helium jacket covering the moderator cell removes the nuclear heating of the outer shell wall of the cell. It contributes to reduce the void fraction of liquid hydrogen in the inner shell. Such a type of a moderator cell is suitable for the CNS with higher nuclear heating. The cold helium gas flows down firstly into the sub-cooling helium jacket and then flows up to the condenser. Therefore, the theory of the self-regulation for the thermo-siphon type of the CNS is also applicable

  10. Strength analysis of CARR-CNS with crescent-shape moderator cell and helium sub-cooling jacket covering cell

    International Nuclear Information System (INIS)

    Yu Qingfeng; Feng Quanke; Kawai Takeshi; Shen Feng; Yuan Luzheng; Cheng Liang

    2005-01-01

    The new type of the moderator cell was developed for the cold neutron source (CNS) of the China Advanced Research Reactor (CARR) which is now being constructed at the China Institute of Atomic Energy in Beijing. A crescent-shape moderator cell covered by the helium sub-cooling jacket is adopted. The structure of the moderator cell is optimized by the stress FEM analysis. A crescent-shape would help to increase the volume of the moderator cell for fitting it to the four cold neutron guide tubes, even if liquid hydrogen, not liquid deuterium, was used as a cold moderator. The helium sub-cooling jacket covering the moderator cell removes the nuclear heating of the outer shell wall of the cell. It contributes to reduce the void fraction of liquid hydrogen in the outer shell of the moderator cell. Such a type of a moderator cell is suitable for the CNS with higher nuclear heating. The cold helium gas flows down first into the helium sub-cooling jacket and then flows up to the condenser. The theory of the self-regulation suitable to the thermo-siphon type of the CNS is also applicable and validated

  11. CARR-CNS with crescent-shape moderator cell and sub-cooling helium jacket surrounding cell

    International Nuclear Information System (INIS)

    Yu, Qingfeng; Feng, Quanke; Kawai, Takeshi; Shen, Feng; Yuan, Luzheng

    2005-01-01

    The new type of the moderator cell was developed for the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR) which is now constructing at the China Institute of Atomic Energy in Beijing. A crescent-shape moderator cell covered by the sub-cooling helium jacket is adopted. A crescent-shape would help to increase the volume of the moderator cell for corresponding it to the 4 cold neutron guide tubes, even if liquid hydrogen not liquid deuterium were used as a cold moderator. The sub-cooling helium jacket covering the moderator cell removes the nuclear heating of the outer shell wall of the cell. It contributes to reduce the void fraction of liquid hydrogen in the inner shell. Such a type of a moderator cell is suitable for the CNS with higher nuclear heating. The cold helium gas flows down firstly into the sub-cooling helium jacket and then flows up to the condenser. Therefore, the theory of the self-regulation for the thermo-siphon type of the CNS is also applicable

  12. Theoretical study on guided wave propagation in (1 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (x = 0.29 and 0.33) single crystal plates

    International Nuclear Information System (INIS)

    Chen Chuanwen; Zhang Rui; Cao Wenwu

    2009-01-01

    The propagation of guided waves in free standing (1 - x)Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 [PMN-xPT] (x = 0.29 or 0.33) single crystal plates has been studied theoretically. The polar directions are in the (111) family directions of the cubic reference coordinates but the crystals are being polarized along [0 0 1] c , [0 1 1] c and [1 1 1] c of the cubic reference directions so that the effective microscopic symmetries are 4mm, mm2 and 3m, respectively. Multiple mode couplings appear in the dispersion curves for both the symmetric and the antisymmetric Lamb and shear horizontal modes. The velocities of most guided waves decrease rapidly with frequency. Then, after passing a minimum, they begin to increase with frequency and eventually saturate to the shear wave velocity v sz (or v 1 = 3507 m s -1 for [1 1 1] c polarized sample). For a [1 1 1] c polarized single domain PMN-0.33PT sample, the S 1 mode instead of the S 0 mode approaches the Rayleigh velocity v R at high frequencies.

  13. The shifting landscape of metastatic breast cancer to the CNS.

    Science.gov (United States)

    Quigley, Matthew R; Fukui, Olivia; Chew, Brandon; Bhatia, Sanjay; Karlovits, Steven

    2013-07-01

    The improved survival following the diagnosis of breast cancer has potentially altered the characteristics and course of patients presenting with CNS involvement. We therefore sought to define our current cohort of breast cancer patients with metastatic disease to the CNS in regard to modern biomarkers and clinical outcome. Review of clinical and radiographic records of women presenting to a tertiary medical center with the new diagnosis of CNS metastatic disease from breast cancer. This was a retrospective review from patients identities obtained from two prospective databases. There were 88 women analyzed who were treated over the period of January 2003 to February 2010, average age 56.9 years. At the time of initial presentation of CNS disease, 68 % of patients had multiple brain metastases, 17 % had a solitary metastasis, and 15 % had only leptomeningeal disease (LMD). The median survival for all patients from the time of diagnosis of breast disease was 50.0 months, and 9.7 months from diagnosis of CNS involvement. The only factor related to overall survival was estrogen receptor-positive pathology (57.6 v. 38.2 months, p = .02 log-rank); those related to survival post CNS diagnosis were presentation with LMD (p = .004, HR = 3.1, Cox regression) and triple-negative hormonal/HER2 status (p = .02, HR = 2.3, Cox regression). Patients with either had a median survival of 3.1 months (no patients in common). Of the 75 patients who initially presented with metastatic brain lesions, 20 (26 %) subsequently developed LMD in the course of their disease (median 10.4 months), following which survival was grim (1.8 months median). Symptoms of LMD were most commonly lower extremity weakness (14/33), followed by cranial nerve deficits (11/33). The recently described Graded Prognostic Assessment (GPA) tumor index stratified median survival at 2.5, 5.9, 13.1, and 21.7 months, respectively, for indices of 1-4 (p = .004, log-rank), which

  14. Prediction of human CNS pharmacokinetics using a physiologically-based pharmacokinetic modeling approach

    NARCIS (Netherlands)

    Yamamoto, Yumi; Valitalo, Pyry A.; Wong, Yin Cheong; Huntjens, Dymphy R.; Proost, Johannes H.; Vermeulen, An; Krauwinkel, Walter; Beukers, Margot W.; Kokki, Hannu; Kokki, Merja; Danhof, Meindert; van Hasselt, Johan G. C.; de Lange, Elizabeth C. M.

    2018-01-01

    Knowledge of drug concentration-time profiles at the central nervous system (CNS) target-site is critically important for rational development of CNS targeted drugs. Our aim was to translate a recently published comprehensive CNS physiologically-based pharmacokinetic (PBPK) model from rat to human,

  15. Tendencies the treatment of the central nervous system (CNS) tumors

    International Nuclear Information System (INIS)

    Alert Silva, Jose; Jimenez Medina, Jose

    2004-01-01

    It is known that the treatment of the central nervous system (CNS) tumors is based on the use of surgery and radiotherapy (RT) and that chemotherapy (QMT) is used even more, as well as the other drugs. A bibliographic review was made to update the knowledge on the current trends and perspectives of RT applied to CNS tumors. The following were found among them: a) combinations of RT and CMT; b) radiosensitizers incorporated to the radiant treatment; c) angiogenesis inhibitors associated with RT; d) the scale-up or increase of the RT doses thanks to the development of new technologies, such as 3 D conformal radiotherapy, intensity- modulated radiotherapy, surgery and others. Another field of research is that of the changes in the rhythm or fractioning of the RT: hyperfractionated, accelerated, combinations of both, etc., which will allow mainly to increase the dosage scale-up

  16. CNS-targets in control of energy and glucose homeostasis.

    Science.gov (United States)

    Kleinridders, André; Könner, A Christine; Brüning, Jens C

    2009-12-01

    The exceeding efforts in understanding the signals initiated by nutrients and hormones in the central nervous system (CNS) to regulate glucose and energy homeostasis have largely revolutionized our understanding of the neurocircuitry in control of peripheral metabolism. The ability of neurons to sense nutrients and hormones and to adopt a coordinated response to these signals is of crucial importance in controlling food intake, energy expenditure, glucose and lipid metabolism. Anatomical lesion experiments, pharmacological inhibition of signaling pathways, and, more recently, the analysis of conditional mouse mutants with modifications of hormone and nutrient signaling in defined neuronal populations have broadened our understanding of these complex neurocircuits. This review summarizes recent findings regarding the role of the CNS in sensing and transmitting nutritional and hormonal signals to control energy and glucose homeostasis and aims to define them as potential novel drug targets for the treatment of obesity and type 2 diabetes mellitus.

  17. 4th ENRI International Workshop on ATM/CNS

    CERN Document Server

    2017-01-01

    This book is a compilation of selected papers from the 4th ENRI International Workshop on ATM/CNS (EIWAC2015). The work focuses on novel techniques for aviation infrastructure in air traffic management (ATM) and communications, navigation, surveillance, and informatics (CNSI) domains. The contents make valuable contributions to academic researchers, engineers in the industry, and regulators of aviation authorities. As well, readers will encounter new ideas for realizing a more efficient and safer aviation system. .

  18. Morphological evaluation of fetus CNS and its related anomalies

    International Nuclear Information System (INIS)

    Oi, Shizuo; Tamaki, Norihiko; Matsumoto, Satoshi; Katayama, Kazuaki; Mochizuki, Matsuto

    1989-01-01

    The fetus central nervous system was evaluated morphologically by ultrasonography (US), magnetic resonance imaging (MRI), and CT scan to analyze the prenatal diagnostic value for CNS anomalies. A total of 31 patients with 42 lesions had been diagnosed during the preceding 7 years. The patients included 24 with hydrocephalus, three with anencephaly, three with myeloschisis, three with holoprosencephaly, three with an encephalocele, two with a Dandy-Walker cyst, one with hydroencephalodysplasia, one with an intracranial neoplasm, one with sacrococcygeal teratoma, and one with sacral agenesis. Compared with US and MRI, CT proved to be more accurate in the detection of spine and cranium-bone morphology. This finding seems to be valuable in the diagnosis of spina bifida, cranium bifidum and some cases of hypertensive hydrocephalus, especially in the axial view. MRI was definitely superior in the anatomico-pathological diagnosis of cerebral dysgenesis, ventriculomegaly, intracranial tumors, and other brain parenchymal changes in view of multi-dimensional analysis. The most considerable disadvantage of MRI in the diagnosis of a fetus CNS anomaly is the poor information about spine and cranium morphology. A super-conducting MRI system is still insufficient to demonstrate the spinal cord of a fetus. US was routinely used, and the multidimensional slices were useful for screening the CNS abnormalies. Some of the fetus brain lesions, such as intracranial hematomas, had a specific echogenecity on US. However, US sometimes failed to demarcate the cerebral parenchymal or subdural morphological changes because its artifacts had hyperchoic shadows. While US, MRI, and CT were valuable diagnostic tools in the morphological evaluation of fetus CNS and its related anomalies, each modality has different diagnostic advantages and disadvantages. Improvement can be expected when these diagnostic imaging modalities are complementary, depending upon the nature of the anatomy. (J.P.N.)

  19. Primary CNS lymphoma in nonimmunocompromised patients magnetic resonance study

    International Nuclear Information System (INIS)

    Pena, J.; Fernandez, J.M.; Galarraga, M.I.; Pozo, A.; Montes, A.; Ablanedo, P.

    1995-01-01

    Prymary lymphoma of the CNS (PLCNS) is a relatively infrequent malignant tumor that has become increasingly common over the past decade. The radiological signs, although not pathognomonic, are quite specific and suggestive of the correct diagnosis, thus facilitating therapeutic management. We present six cases of PLCNS in nonimmunocopromised patients studied by MR in our hospital over the past two and a half years. We describe theradiological findings, correlating them with those mentioned in the literature. 14 refs

  20. Melanocortin signaling in the CNS directly regulates circulating cholesterol

    OpenAIRE

    Perez-Tilve, Diego; Hofmann, Susanna M; Basford, Joshua; Nogueiras, Ruben; Pfluger, Paul T; Patterson, James T; Grant, Erin; Wilson-Perez, Hilary E; Granholm, Norman A; Arnold, Myrtha; Trevaskis, James L; Butler, Andrew A; Davidson, William S; Woods, Stephen C; Benoit, Stephen C

    2010-01-01

    Cholesterol circulates in the blood in association with triglycerides and other lipids, and elevated blood low-density lipoprotein cholesterol carries a risk for metabolic and cardiovascular disorders, whereas high-density lipoprotein (HDL) cholesterol in the blood is thought to be beneficial. Circulating cholesterol is the balance among dietary cholesterol absorption, hepatic synthesis and secretion, and the metabolism of lipoproteins by various tissues. We found that the CNS is also an impo...

  1. Computerized tomography data on CNS affection in systemic lupus erythematosus

    International Nuclear Information System (INIS)

    Ivanova, M.M.; Bliznyuk, O.I.; Todua, F.I.; Tumanova, A.A.

    1989-01-01

    Computed tomography (CT) of the brain was employed in 40 patients with systemic lupus erythematosus (SLE). Clinical cerebral pathology was obvious in 30 and absent in 10 patients. By CT cerebral symptoms were divided of 4 groups. Clinical symptom complexes of CNS defects and SLE were reflected on definite CT images correlated with focal damage to the brain. CT picture of enlarged subarachnoid space, ventricles and basal cisterns can be observed in SLE patients without neurological symptoms. This indicated likely subclinical cerebral affection

  2. EMMPRIN, an upstream regulator of MMPs, in CNS biology.

    Science.gov (United States)

    Kaushik, Deepak Kumar; Hahn, Jennifer Nancy; Yong, V Wee

    2015-01-01

    Matrix metalloproteinases (MMPs) are engaged in pathologies associated with infections, tumors, autoimmune disorders and neurological dysfunctions. With the identification of an upstream regulator of MMPs, EMMPRIN (Extracellular matrix metalloproteinase inducer, CD147), it is relevant to address if EMMPRIN plays a role in the pathology of central nervous system (CNS) diseases. This would enable the possibility of a more upstream and effective therapeutic target. Indeed, conditions including gliomas, Alzheimer's disease (AD), multiple sclerosis (MS), and other insults such as hypoxia/ischemia show elevated levels of EMMPRIN which correlate with MMP production. In contrast, given EMMPRIN's role in CNS homeostasis with respect to regulation of monocarboxylate transporters (MCTs) and interactions with adhesion molecules including integrins, we need to consider that EMMPRIN may also serve important regulatory or protective functions. This review summarizes the current understanding of EMMPRIN's involvement in CNS homeostasis, its possible roles in escalating or reducing neural injury, and the mechanisms of EMMPRIN including and apart from MMP induction. Copyright © 2015 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.

  3. Mechanisms of CNS invasion and damage by parasites.

    Science.gov (United States)

    Kristensson, Krister; Masocha, Willias; Bentivoglio, Marina

    2013-01-01

    Invasion of the central nervous system (CNS) is a most devastating complication of a parasitic infection. Several physical and immunological barriers provide obstacles to such an invasion. In this broad overview focus is given to the physical barriers to neuroinvasion of parasites provided at the portal of entry of the parasites, i.e., the skin and epithelial cells of the gastrointestinal tract, and between the blood and the brain parenchyma, i.e., the blood-brain barrier (BBB). A description is given on how human pathogenic parasites can reach the CNS via the bloodstream either as free-living or extracellular parasites, by embolization of eggs, or within red or white blood cells when adapted to intracellular life. Molecular mechanisms are discussed by which parasites can interact with or pass across the BBB. The possible targeting of the circumventricular organs by parasites, as well as the parasites' direct entry to the brain from the nasal cavity through the olfactory nerve pathway, is also highlighted. Finally, examples are given which illustrate different mechanisms by which parasites can cause dysfunction or damage in the CNS related to toxic effects of parasite-derived molecules or to immune responses to the infection. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. CNS Involvement in Hemophagocytic Lymphohistiocytosis: CT and MR Findings

    International Nuclear Information System (INIS)

    Chung, Tae Woong

    2007-01-01

    Hemophagocytic lymphohistiocytosis (HLH) is a rare disorder that is characterized by proliferation of benign histiocytes, and this commonly involves the liver, spleen, lymph nodes, bone marrow and central nervous system (CNS). We report here on the CT and MR imaging findings in a case of CNS HLH that showed multiple ring enhancing masses mimicking abscess or another mass on the CT and MR imaging. emophagocytic lymphohistiocytosis (HLH) is a rare disorder that is characterized by nonmalignant diffuse infiltration of multiple organs, including the central nervous system (CNS), by lymphocytes and histiocytes (1). Many radiologic reports describing diffuse white matter infiltrations, parenchymal atrophy and calcification have been published, but the characteristics of these findings remain non-specific, especially in immunocompromised patients. We present here a case of HLH in a 3-year-old boy who presented with multiple ring enhancing lesions involving the brain. In conclusion, although the CT and MRI findings of HLH with ring enhancing parenchymal lesions are nonspecific and mimic abscess, and especially in the immunosuppressed patients, increased diffusion at the center on DWI may be a finding of HLH to differentiate it from abscess, which has restricted diffusion at the center. However, the pathologic correlation with DWI according to the lesion stage certainly needs further study with a larger number of patients

  5. Adverse CNS-effects of beta-adrenoceptor blockers.

    Science.gov (United States)

    Gleiter, C H; Deckert, J

    1996-11-01

    In 1962 propranolol, the first beta adrenoceptor antagonist (beta blocker), was brought on to the market. There is now a host of different beta blockers available, and these compounds are among the most commonly prescribed groups of drugs. The efficacy of beta blockers has been proven predominantly for the treatment of cardiovascular diseases. Beta blockers are also used for certain types of CNS disorders, such as anxiety disorders, essential tremor and migraine. While low toxicity means that they have a favorable risk-benefit ratio, given the high intensity of use, it is essential to have a comprehensive knowledge of adverse events. Adverse events of beta blockers that can be related to the CNS are quite often neglected, even in textbooks of clinical pharmacology or review articles, and thus often misdiagnosed. The following article, therefore, after summarizing the use of beta blockers for CNS indications, critically reviews the literature on centrally mediated adverse events. General pharmacological features of beta blockers and their molecular basis of action will briefly be addressed to the extent that they are or may become relevant for central nervous pharmacotherapy and side-effects.

  6. Microtubule-Targeting Agents Enter the Central Nervous System (CNS): Double-edged Swords for Treating CNS Injury and Disease.

    Science.gov (United States)

    Hur, Eun-Mi; Lee, Byoung Dae

    2014-12-01

    Microtubules have been among the most successful targets in anticancer therapy and a large number of microtubule-targeting agents (MTAs) are in various stages of clinical development for the treatment of several malignancies. Given that injury and diseases in the central nervous system (CNS) are accompanied by acute or chronic disruption of the structural integrity of neurons and that microtubules provide structural support for the nervous system at cellular and intracellular levels, microtubules are emerging as potential therapeutic targets for treating CNS disorders. It has been postulated that exogenous application of MTAs might prevent the breakdown or degradation of microtubules after injury or during neurodegeneration, which will thereby aid in preserving the structural integrity and function of the nervous system. Here we review recent evidence that supports this notion and also discuss potential risks of targeting microtubules as a therapy for treating nerve injury and neurodegenerative diseases.

  7. Microtubule-Targeting Agents Enter the Central Nervous System (CNS: Double-edged Swords for Treating CNS Injury and Disease

    Directory of Open Access Journals (Sweden)

    Eun-Mi Hur

    2014-12-01

    Full Text Available Microtubules have been among the most successful targets in anticancer therapy and a large number of microtubule-targeting agents (MTAs are in various stages of clinical development for the treatment of several malignancies. Given that injury and diseases in the central nervous system (CNS are accompanied by acute or chronic disruption of the structural integrity of neurons and that microtubules provide structural support for the nervous system at cellular and intracellular levels, microtubules are emerging as potential therapeutic targets for treating CNS disorders. It has been postulated that exogenous application of MTAs might prevent the breakdown or degradation of microtubules after injury or during neurodegeneration, which will thereby aid in preserving the structural integrity and function of the nervous system. Here we review recent evidence that supports this notion and also discuss potential risks of targeting microtubules as a therapy for treating nerve injury and neurodegenerative diseases.

  8. Automatic guided wave communication system using steel pipes as communication channel for flood detection in steel offshoreoilrigs; Sistema automatico de comunicacion de ondas guiadas para la deteccion de tubos de refuerzo inundados en plataformas petroleras costa fuera

    Energy Technology Data Exchange (ETDEWEB)

    Mijarez Cstro, Rito; Martinez Ramirez, Fernando [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2010-10-09

    An automatic guided wave Pulse Position Modulation (PPM) system, using steel tubes as communication channel, for detecting flooding in the hollow sub-sea structures of offshore oilrigs is presented. The system employs two smart piezoelectric based sensors and modulators and a demodulator based on a piezoelectric transducer, a Digital Signal Processor (DSP) and a microcontroller. Experiments performed in the laboratory, in a tubular steel heliport structure and the base of a deck of an oilrig under construction, have successfully distinguished automatically guided wave encoded information. [Spanish] Este articulo presenta un trabajo de investigacion en el cual se desarrolla un sistema automatico de comunicacion de ondas guiadas por modulacion por posicion de pulsos (PPM), orientado a la deteccion de miembros inundados en los tubos de refuerzo de las plataformas petroleras costa fuera. El sistema utiliza de manera novedosa tubos de acero como medio de comunicacion y emplea dos sensores/moduladores inteligentes compuestos de cristales piezoelectricos, electronica basada en un microcontrolador y baterias. La instrumentacion del demodulador consta de un transductor piezoelectrico de ultrasonido, un procesador digital de senales (DSP) y un microcontrolador, el cual lleva a cabo de manera automatica la deteccion de ondas guiadas. Los experimentos se realizaron en aire, en laboratorio, en una estructura tubular de acero del helipuerto y en la base de una plataforma bajo construccion.

  9. Quasi-optical millimeter wave rotating TE62 mode generator

    International Nuclear Information System (INIS)

    Li Shaopu; Zhang Conghui; Wang Zhong; Guo Feng; Chen Hongbin; Hu Linlin; Pan Wenwu

    2011-01-01

    The design,measurement technique and experimental results of rotating TE 6 2 mode generator are presented. The source includes millimeter wave optical system and open coaxial wave guide system. The millimeter wave optical system consists of pyramid antenna, hyperbolical reflector, parabolic reflector and quasi parabolic reflector. The open coaxial wave guide system contains open coaxial wave guide cavity, cylinder wave guide and output antenna. It is tested by network analyser and millimeter wave near field pattern auto-test system, and the purity of rotating TE 6 2 mode at 96.4 GHz is about 97%. (authors)

  10. Endovascular transplantation of stem cells to the injured rat CNS

    International Nuclear Information System (INIS)

    Lundberg, Johan; Soederman, Mikael; Andersson, Tommy; Holmin, Staffan; Le Blanc, Katarina

    2009-01-01

    Transplantation procedures using intraparenchymal injection of stem cells result in tissue injury in addition to associated surgical risks. Intravenous injection of mesenchymal stem cells gives engraftment to lesions, but the method has low efficiency and specificity. In traumatic brain injuries (TBI), there is a transient breakdown of the blood-brain barrier and an inflammatory response, which increase migration of cells from blood to parenchyma. The aim of this investigation was to analyze the effect of intra-arterial administration on cellular engraftment. Experimental TBI was produced in a rat model. Endovascular technique was used to administer human mesenchymal stem cells in the ipsilateral internal carotid artery. Evaluation of engraftment and side effects were performed by immunohistochemical analysis of the brain and several other organs. The results were compared to intravenous administration of stem cells. Intra-arterial transplantion of mesenchymal stem cells resulted in central nervous system (CNS) engraftment without thromboembolic ischemia. We observed a significantly higher number of transplanted cells in the injured hemisphere after intra-arterial compared to intravenous administration both 1 day (p<0.01) and 5 days (p<0.05) after the transplantation. Some cells were also detected in the spleen but not in the other organs analyzed. Selective intra-arterial administration of mesenchymal stem cells to the injured CNS is a minimally invasive method for transplantation. The method is significantly more efficient than the intravenous route and causes no side effects in the current model. The technique can potentially be used for repeated transplantation to the CNS after TBI and in other diseases. (orig.)

  11. Endovascular transplantation of stem cells to the injured rat CNS

    Energy Technology Data Exchange (ETDEWEB)

    Lundberg, Johan; Soederman, Mikael; Andersson, Tommy; Holmin, Staffan [Karolinska University Hospital, Department of Clinical Neuroscience, Karolinska Institutet, Department of Neuroradiology, Stockholm (Sweden); Le Blanc, Katarina [Karolinska University Hospital, Department of Stem Cell Research, Karolinska Institutet, Department of Clinical Immunology, Stockholm (Sweden)

    2009-10-15

    Transplantation procedures using intraparenchymal injection of stem cells result in tissue injury in addition to associated surgical risks. Intravenous injection of mesenchymal stem cells gives engraftment to lesions, but the method has low efficiency and specificity. In traumatic brain injuries (TBI), there is a transient breakdown of the blood-brain barrier and an inflammatory response, which increase migration of cells from blood to parenchyma. The aim of this investigation was to analyze the effect of intra-arterial administration on cellular engraftment. Experimental TBI was produced in a rat model. Endovascular technique was used to administer human mesenchymal stem cells in the ipsilateral internal carotid artery. Evaluation of engraftment and side effects were performed by immunohistochemical analysis of the brain and several other organs. The results were compared to intravenous administration of stem cells. Intra-arterial transplantion of mesenchymal stem cells resulted in central nervous system (CNS) engraftment without thromboembolic ischemia. We observed a significantly higher number of transplanted cells in the injured hemisphere after intra-arterial compared to intravenous administration both 1 day (p<0.01) and 5 days (p<0.05) after the transplantation. Some cells were also detected in the spleen but not in the other organs analyzed. Selective intra-arterial administration of mesenchymal stem cells to the injured CNS is a minimally invasive method for transplantation. The method is significantly more efficient than the intravenous route and causes no side effects in the current model. The technique can potentially be used for repeated transplantation to the CNS after TBI and in other diseases. (orig.)

  12. Immune and inflammatory responses in the CNS : Modulation by astrocytes

    DEFF Research Database (Denmark)

    Penkowa, Milena; aschner, michael; hidalgo, juan

    2008-01-01

    Beyond their long-recognized support functions, astrocytes are active partners of neurons in processing information, synaptic integration, and production of trophic factors, just to name a few. Both microglia and astrocytes produce and secrete a number of cytokines, modulating and integrating...... the communication between hematogenous cells and resident cells of the central nervous system (CNS). This review will address (1) the functions of astrocytes in the normal brain and (2) their role in surveying noxious stimuli within the brain, with particular emphasis on astrocytic responses to damage or disease...

  13. Kynurenines in CNS disease: regulation by inflammatory cytokines

    Science.gov (United States)

    Campbell, Brian M.; Charych, Erik; Lee, Anna W.; Möller, Thomas

    2014-01-01

    The kynurenine pathway (KP) metabolizes the essential amino acid tryptophan and generates a number of neuroactive metabolites collectively called the kynurenines. Segregated into at least two distinct branches, often termed the “neurotoxic” and “neuroprotective” arms of the KP, they are regulated by the two enzymes kynurenine 3-monooxygenase and kynurenine aminotransferase, respectively. Interestingly, several enzymes in the pathway are under tight control of inflammatory mediators. Recent years have seen a tremendous increase in our understanding of neuroinflammation in CNS disease. This review will focus on the regulation of the KP by inflammatory mediators as it pertains to neurodegenerative and psychiatric disorders. PMID:24567701

  14. Condition Assessment of Foundation Piles and Utility Poles Based on Guided Wave Propagation Using a Network of Tactile Transducers and Support Vector Machines

    Directory of Open Access Journals (Sweden)

    Ulrike Dackermann

    2017-12-01

    Full Text Available This paper presents a novel non-destructive testing and health monitoring system using a network of tactile transducers and accelerometers for the condition assessment and damage classification of foundation piles and utility poles. While in traditional pile integrity testing an impact hammer with broadband frequency excitation is typically used, the proposed testing system utilizes an innovative excitation system based on a network of tactile transducers to induce controlled narrow-band frequency stress waves. Thereby, the simultaneous excitation of multiple stress wave types and modes is avoided (or at least reduced, and targeted wave forms can be generated. The new testing system enables the testing and monitoring of foundation piles and utility poles where the top is inaccessible, making the new testing system suitable, for example, for the condition assessment of pile structures with obstructed heads and of poles with live wires. For system validation, the new system was experimentally tested on nine timber and concrete poles that were inflicted with several types of damage. The tactile transducers were excited with continuous sine wave signals of 1 kHz frequency. Support vector machines were employed together with advanced signal processing algorithms to distinguish recorded stress wave signals from pole structures with different types of damage. The results show that using fast Fourier transform signals, combined with principal component analysis as the input feature vector for support vector machine (SVM classifiers with different kernel functions, can achieve damage classification with accuracies of 92.5% ± 7.5%.

  15. The Wave Energy Sector

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter

    2017-01-01

    This Handbook for Ocean Wave Energy aims at providing a guide into the field of ocean wave energy utilization. The handbook offers a concise yet comprehensive overview of the main aspects and disciplines involved in the development of wave energy converters (WECs). The idea for the book has been...... shaped by the development, research, and teaching that we have carried out at the Wave Energy Research Group at Aalborg University over the past decades. It is our belief and experience that it would be useful writing and compiling such a handbook in order to enhance the understanding of the sector...

  16. Non-diffractive waves

    CERN Document Server

    Hernandez-Figueroa, Hugo E; Recami, Erasmo

    2013-01-01

    This continuation and extension of the successful book ""Localized Waves"" by the same editors brings together leading researchers in non-diffractive waves to cover the most important results in their field and as such is the first to present the current state.The well-balanced presentation of theory and experiments guides readers through the background of different types of non-diffractive waves, their generation, propagation, and possible applications. The authors include a historical account of the development of the field, and cover different types of non-diffractive waves, including Airy

  17. Neurotransmitter synthesis from CNS glutamine for central control of breathing

    International Nuclear Information System (INIS)

    Hoop, B.; Systrom, D.; Chiang, C.H.; Shih, V.E.; Kazemi, H.

    1986-01-01

    The maximum rate at which CNS glutamine (GLN) derived from glutamate (GLU) can be sequestered for synthesis of neurotransmitter GLU and/or γ-aminobutyric acid (GABA) has been determined in pentobarbital-anesthetized dogs. A total of 57 animals were studied under normal, hypoxic (Pa/sub O2/ greater than or equal to 20 mmHg), or hypercapnic (Pa/sub CO2/ less than or equal to 71 mm Hg) conditions. Thirteen of these were bilaterally vagotomized and carotid body denervated and studied only under normoxic or hypoxic conditions. In 5 animals cerebrospinal fluid GLN transfer rate constant k was measured using 13 N-ammonia tracer. Measured cerebral cortical (CC) and medullary (MED) GLN concentrations c are found to vary with GLU metabolic rate r according to c-C/sub m/r/(r+R), where r, the product of k and corresponding tissue GLU concentration, is assumed equal to the maximum GLN metabolic rate via pathways other than for neurotransmitter synthesis. The constants C/sub m/ and R are the predicted maximum GLN concentration and its maximum rate of sequestration for neurotransmitter synthesis, respectively. For both CNS tissue types in all animals, C/sub m/ = 20.9 +- 7.4 (SD) mmoles/kg wet wt(mM) and R = 6.2 +- 2.3 mM/min. These values are consistent with results obtained in anesthetized rats

  18. Primary CNS lymphoma as a cause of Korsakoff syndrome.

    Science.gov (United States)

    Toth, Cory; Voll, Chris; Macaulay, Robert

    2002-01-01

    Korsakoff syndrome presents with memory dysfunction with retrograde amnesia, anterograde amnesia, limited insight into dysfunction, and confabulation. The most common etiology of Korsakoff syndrome is thiamine deficiency secondary to alcoholism. There are limited case reports of structural lesions causing Korsakoff syndrome. A 46-year-old male with a long history of alcoholism presented with a history of confusion, amnesia, and confabulation with no localizing features on neurological examination. The patient showed no clinical change with intravenous thiamine. Computed tomography of the brain revealed a heterogenous, enhancing mass lesion centered within the third ventricle, with other lesions found throughout cortical and subcortical regions. The patient was given dexamethasone i.v. without noticeable clinical improvement but with marked radiological improvement with mass reduction. Stereotactic biopsy revealed a diagnosis of primary central nervous system (CNS) lymphoma. Most patients presenting with Korsakoff syndrome have thiamine deficiency; however, mass lesions can produce an identical clinical picture. This is the first case report of a patient with primary CNS lymphoma presenting as Korsakoff syndrome.

  19. Glibenclamide for the Treatment of Acute CNS Injury

    Directory of Open Access Journals (Sweden)

    J. Marc Simard

    2013-10-01

    Full Text Available First introduced into clinical practice in 1969, glibenclamide (US adopted name, glyburide is known best for its use in the treatment of diabetes mellitus type 2, where it is used to promote the release of insulin by blocking pancreatic KATP [sulfonylurea receptor 1 (Sur1-Kir6.2] channels. During the last decade, glibenclamide has received renewed attention due to its pleiotropic protective effects in acute CNS injury. Acting via inhibition of the recently characterized Sur1-Trpm4 channel (formerly, the Sur1-regulated NCCa-ATP channel and, in some cases, via brain KATP channels, glibenclamide has been shown to be beneficial in several clinically relevant rodent models of ischemic and hemorrhagic stroke, traumatic brain injury, spinal cord injury, neonatal encephalopathy of prematurity, and metastatic brain tumor. Glibenclamide acts on microvessels to reduce edema formation and secondary hemorrhage, it inhibits necrotic cell death, it exerts potent anti-inflammatory effects and it promotes neurogenesis—all via inhibition of Sur1. Two clinical trials, one in TBI and one in stroke, currently are underway. These recent findings, which implicate Sur1 in a number of acute pathological conditions involving the CNS, present new opportunities to use glibenclamide, a well-known, safe pharmaceutical agent, for medical conditions that heretofore had few or no treatment options.

  20. Nuclear innovation through collaboration. 35th Annual CNS conference and 39th CNS/CNA student conference

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-07-01

    The Canadian Nuclear Society (CNS) held its 35th Annual Conference in Saint John, New Brunswick, Canada on May 31 to June 3, 2015, combined with the 39th Annual CNS/CNA Student Conference. With the theme of the conference, 'Nuclear Innovation through Collaboration', more than 425 delegates, exhibitors and students were in attendance. The conference commenced with two strong plenary sessions on Utility Collaborations to Improve Lifetime Performance; and, Performance Improvement Programs: Goals and Experience. The second day consisted of the panel discussions on International Developments in Used Nuclear Fuel Repository Programs, and two plenary sessions on: Enterprise Risk Management; and, Vendor Role in a Continuously Improving Industry. The third day contained a number of interesting features, including plenary sessions on Waste Management and Decommissioning; Developing Technologies and Resources, and a panel discussion on the Transportation of Used Nuclear Fuel. All three days of the conference also contained parallel sessions with over 100 technical papers presented at the main and student sessions. The technical session titles were: Refurbishment and Life Extension; Thermalhydraulics; Nuclear Materials; WMD - Radiation Monitoring; Safety and Licensing; Communication; Safety and Licensing; Instrumentation and Control; Advanced Reactor Designs; WMD - Deep Geological Repository Packaging; Reactor Physics; Chemistry and Materials; Advanced Fuel Cycles; Waste Management and Decommissioning; and, Medical Physics and Radiation Biology.

  1. Nuclear innovation through collaboration. 35th Annual CNS conference and 39th CNS/CNA student conference

    International Nuclear Information System (INIS)

    2015-01-01

    The Canadian Nuclear Society (CNS) held its 35th Annual Conference in Saint John, New Brunswick, Canada on May 31 to June 3, 2015, combined with the 39th Annual CNS/CNA Student Conference. With the theme of the conference, 'Nuclear Innovation through Collaboration', more than 425 delegates, exhibitors and students were in attendance. The conference commenced with two strong plenary sessions on Utility Collaborations to Improve Lifetime Performance; and, Performance Improvement Programs: Goals and Experience. The second day consisted of the panel discussions on International Developments in Used Nuclear Fuel Repository Programs, and two plenary sessions on: Enterprise Risk Management; and, Vendor Role in a Continuously Improving Industry. The third day contained a number of interesting features, including plenary sessions on Waste Management and Decommissioning; Developing Technologies and Resources, and a panel discussion on the Transportation of Used Nuclear Fuel. All three days of the conference also contained parallel sessions with over 100 technical papers presented at the main and student sessions. The technical session titles were: Refurbishment and Life Extension; Thermalhydraulics; Nuclear Materials; WMD - Radiation Monitoring; Safety and Licensing; Communication; Safety and Licensing; Instrumentation and Control; Advanced Reactor Designs; WMD - Deep Geological Repository Packaging; Reactor Physics; Chemistry and Materials; Advanced Fuel Cycles; Waste Management and Decommissioning; and, Medical Physics and Radiation Biology.

  2. Differential expression of metallothioneins in the CNS of mice with experimental autoimmune encephalomyelitis

    DEFF Research Database (Denmark)

    Espejo, C; Carrasco, J; Hidalgo, J

    2001-01-01

    Multiple sclerosis is an inflammatory, demyelinating disease of the CNS. Metallothioneins-I+II are antioxidant proteins induced in the CNS by immobilisation stress, trauma or degenerative diseases which have been postulated to play a neuroprotective role, while the CNS isoform metallothionein......-III has been related to Alzheimer's disease. We have analysed metallothioneins-I-III expression in the CNS of mice with experimental autoimmune encephalomyelitis. Moreover, we have examined the putative role of interferon-gamma, a pro-inflammatory cytokine, in the control of metallothioneins expression...

  3. 6. CNS international conference on CANDU maintenance. Proceedings

    International Nuclear Information System (INIS)

    2003-01-01

    The 6th CNS International Conference on CANDU Maintenance took place in Toronto, Ontario on November 16-18, 2003. The theme for the conference was 'Maintenance for Life'. About 270 delegates attended the conference held by the Canadian Nuclear Society. The conference consisted of four parallel sessions, a pattern that continued throughout the conference. Papers were grouped under the following headings: Fuel Channels and End Fittings - Assessments; Fuel Channels and End Fittings - Inspections; Fuel Channels and End Fittings - Maintenance; Fuel Channels and End Fittings - Universal Delivery Machine; Water Upgrading; Performance and Plant Life Improvement; Steam Generator Life Management; Steam Generator Modifications; Steam Generators - Inspections; Steam Generators - Assessments; Maintenance Programs; Feeder Inspections; Feeder Assessment and Mitigation; Valve Maintenance; Instrumentation and Control; Inspection Technology; and Fuel Handling

  4. Resveratrol Neuroprotection in Stroke and Traumatic CNS injury

    Science.gov (United States)

    Lopez, Mary; Dempsey, Robert J; Vemuganti, Raghu

    2015-01-01

    Resveratrol, a stilbene formed in many plants in response to various stressors, elicits multiple beneficial effects in vertebrates. Particularly, resveratrol was shown to have therapeutic properties in cancer, atherosclerosis and neurodegeneration. Resveratrol-induced benefits are modulated by multiple synergistic pathways that control oxidative stress, inflammation and cell death. Despite the lack of a definitive mechanism, both in vivo and in vitro studies suggest that resveratrol can induce a neuroprotective state when administered acutely or prior to experimental injury to the CNS. In this review, we discuss the neuroprotective potential of resveratrol in stroke, traumatic brain injury and spinal cord injury, with a focus on the molecular pathways responsible for this protection. PMID:26277384

  5. Brain abscess with an unexpected finding: Actinomyces meyeri CNS infection

    DEFF Research Database (Denmark)

    Eiset, Andreas Halgreen; Thomsen, Marianne Kragh; Wejse, Christian

    -up. The source of infection was most likely periodontitis with spread to the lungs from aspiration or oropharyngeal secretion into the respiratory tract, alternatively from haematogenous spread. Conclusions: We report of the successful treatment of a cerebral abscess caused by A. meyeri with narrow spectrum......Background: CNS infection caused by Actinomyces spp. is rare and the subtype Actinomyces meyeri even rarer. Risk factors include periodontal disease and alcohol overuse. We present a case report of a 54-year-old female with dental and lung foci. Case history: A female was hospitalised with tonic...... oedema. By MRI an abscess was suspected and the patient was transferred to the department of neurosurgery, where drainage was performed. Microscopy revealed gram-positive cocci and gram-negative rods and iv. treatment with ceftriaxone 4g x 1 and metronidazole 1g x 1 was commenced. Pus cultures showed...

  6. Gene therapy for CNS diseases – Krabbe disease

    Directory of Open Access Journals (Sweden)

    Mohammad A. Rafi

    2016-06-01

    Full Text Available This is a brief report of the 19th Annual Meeting of the American Society of Gene and Cell Therapy that took place from May 4th through May 7th, 2016 in Washington, DC, USA. While the meeting provided many symposiums, lectures, and scientific sessions this report mainly focuses on one of the sessions on the "Gene Therapy for central nervous system (CNS Diseases" and specifically on the "Gene Therapy for the globoid cell leukodystrophy or Krabbe disease. Two presentations focused on this subject utilizing two animal models of this disease: mice and dog models. Different serotypes of adeno-associate viral vectors (AAV alone or in combination with bone marrow transplantations were used in these research projects. The Meeting of the ASGCT reflected continuous growth in the fields of gene and cell therapy and brighter forecast for efficient treatment options for variety of human diseases.

  7. Radioprotection of mouse CNS endothelial cells in vivo

    International Nuclear Information System (INIS)

    Lyubimova, N.; Coultas, P.; Martin, R.

    1996-01-01

    Full text: Radioprotection using the minor groove binding DNA ligand Hoechst 33342 has been demonstrated in vitro, and more recently in vivo, in mouse lung. Intravenous administration was used for the lung studies, and both endothelial and alveolar epithelial cells-showed good up-take. Radiation damage to the endothelial cell population has also been postulated as important in late developing radionecrosis of spinal cord and brain. Endothelial cell density in brain can be readily determined by a fluorescent-histochemical technique. Treatment with a monoamine oxidase inhibitor and subsequent injection with L-DOPA results in an accumulation of dopamine (DA) in CNS endothelial cells. DA is converted to a fluorophore by exposure to paraformaldehyde, and cell numbers assayed by fluorescence microscopy. Earlier studies used this technique to monitor post-irradiation changes in endothelial cell density in rodent brain and showed the loss, within 24 hours, of a sensitive subpopulation comprising about 15% of the endothelial cells. Ten minutes after intravenous injection of Hoechst 33342 (80mg/kg) the ligand is confined by its limited penetration to the endothelial cells in mouse brain. When we irradiated at this time, there was protection against early endothelial cell loss. Ablation of the sensitive subpopulation in unprotected mice takes place over a dose range of 1 to 3 Gy γ-rays, but doses between 12 to 20 Gy are required in the presence of ligand. This protection equates to a very high dose modification factor of about 7 and possibly reflects a suppression of apoptosis in the sensitive endothelial subpopulation. The extent to which there is enhanced survival in the endothelial population as a whole and how the observed protection affects late CNS necrosis development has yet to be determined. However present results clearly show potential for the use of DNA-binding radioprotectors with limited penetration for investigations into the relative significance of

  8. Bortezomib-related neuropathy may mask CNS relapse in multiple myeloma: A call for diligence.

    Science.gov (United States)

    Abid, Muhammad Bilal; De Mel, Sanjay; Abid, Muhammad Abbas; Tan, Kong Bing; Chng, Wee Joo

    2016-07-02

    Neuropathy is a common adverse effect of bortezomib. Isolated central nervous system (CNS) relapse in MM remains exceedingly rare and carries a dismal prognosis. We present an unusual case of bortezomib related neuropathy masking a CNS relapse of MM. A 57-year-old female was diagnosed with standard-risk MM with clinical and cytogenetic features not typically associated with CNS involvement. She was treated with 4 cycles of bortezomib/cyclophosphamide/dexamethasone (VCD) and achieved a VGPR, after which she underwent an autologous stem cell transplant (ASCT) followed by bortezomib maintenance. Six months after ASCT she developed symptoms suggestive of peripheral neuropathy which was attributed to bortezomib. However the symptoms persisted despite discontinuation of bortezomib. Imaging and cerebrospinal fluid analysis subsequently confirmed a CNS relapse. CNS involvement in MM (CNS-MM) is uncommon and is considered an aggressive disease. Recently published literature has reported biomarkers with prognostic potential. However, isolated CNS relapse is even less common; an event which carries a very poor prognosis. Given the heterogeneous neurologic manifestations associated with MM, clinical suspicion may be masked by confounding factors such as bortezomib-based therapy. The disease may further remain incognito if the patient does not exhibit any of the high risk features and biomarkers associated with CNS involvement. In the era of proteasome inhibitor (PtdIns)/immunomodulator (IMID)-based therapy for MM which carries neurologic adverse effects, it is prudent to consider CNS relapse early. This case further highlights the need for more robust biomarkers to predict CNS relapse and use of newer novel agents which demonstrate potential for CNS penetration.

  9. Drug Delivery to CNS: Challenges and Opportunities with Emphasis on Biomaterials Based Drug Delivery Strategies.

    Science.gov (United States)

    Khambhla, Ekta; Shah, Viral; Baviskar, Kalpesh

    2016-01-01

    The current epoch has witnessed a lifestyle impregnated with stress, which is a major cause of several neurological disorders. High morbidity and mortality rate due to neurological diseases and disorders have generated a huge social impact. Despite voluminous research, patients suffering from fatal and/or debilitating CNS diseases such as brain tumors, HIV, encephalopathy, Alzheimer's, epilepsy, Parkinson's, migraine and multiple sclerosis outnumbered those suffering from systemic cancer or heart diseases. The brain being a highly sensitive neuronal organ, has evolved with vasculature barriers, which regulates the efflux and influx of substances to CNS. Treatment of CNS diseases/disorders is challenging because of physiologic, metabolic and biochemical obstacles created by these barriers which comprise mainly of BBB and BCFB. The inability of achieving therapeutically active concentration has become the bottleneck level difficulty, hampering the therapeutic efficiency of several promising drug candidates for CNS related disorders. Parallel maturation of an effective CNS drug delivery strategy with CNS drug discovery is the need of the hour. Recently, the focus of the pharmaceutical community has aggravated in the direction of developing novel and more efficient drug delivery systems, giving the potential of more effective and safer CNS therapies. The present review outlines several hurdles in drug delivery to the CNS along with ideal physicochemical properties desired in drug substance/formulation for CNS delivery. The review also focuses on different conventional and novel strategies for drug delivery to the CNS. The article also assesses and emphasizes on possible benefits of biomaterial based formulations for drug delivery to the CNS.

  10. Contribution to a torsional wave guide for the measurement of compressible fluids; Contribution a la theorie d'un guide a onde de torsion pour la mesure de niveau de liquides compressibles

    Energy Technology Data Exchange (ETDEWEB)

    Goubel-Lenoel, A

    1999-10-01

    In order to provide complementary means for measurement of water levels in pressurized vessels of nuclear reactors, the possibilities of an immersed torsional wave sensor are being looked into. It has already been modeled, considering an incompressible fluid. Yet, because the fluid can turn into a two-phase fluid, we have investigated how to extend the existing model. As a first step, we have taken into account the compressibility of the surrounding fluid. We focus on a cylindrical waveguide with an elliptic cross-section. Its transverse dimensions are small compared with its length and the wavelengths in the fluid. We start with the elasticity equations for the waveguide. Then, from the exact expression of the pressure exerted by the fluid on the waveguide boundary, a long wavelength approximation is obtained. We end by applying Hamilton's principle of energy conservation, which leads to an approximate equation governing the fluid-loaded waveguide motion, and to an expression of the apparent phase velocity of the torsional wave in the immersed waveguide. Finally, fluid level measurement is possible. Some simulations are made, highlighting the influence of the compressibility. (author)

  11. Integrated coherent matter wave circuits

    International Nuclear Information System (INIS)

    Ryu, C.; Boshier, M. G.

    2015-01-01

    An integrated coherent matter wave circuit is a single device, analogous to an integrated optical circuit, in which coherent de Broglie waves are created and then launched into waveguides where they can be switched, divided, recombined, and detected as they propagate. Applications of such circuits include guided atom interferometers, atomtronic circuits, and precisely controlled delivery of atoms. We report experiments demonstrating integrated circuits for guided coherent matter waves. The circuit elements are created with the painted potential technique, a form of time-averaged optical dipole potential in which a rapidly moving, tightly focused laser beam exerts forces on atoms through their electric polarizability. Moreover, the source of coherent matter waves is a Bose-Einstein condensate (BEC). Finally, we launch BECs into painted waveguides that guide them around bends and form switches, phase coherent beamsplitters, and closed circuits. These are the basic elements that are needed to engineer arbitrarily complex matter wave circuitry

  12. Effectiveness of Prescription-Based CNS Stimulants on Hospitalization in Patients With Schizophrenia

    DEFF Research Database (Denmark)

    Rohde, Christopher; Polcwiartek, Christoffer; Asztalos, Marton

    2018-01-01

    were used to investigate the effectiveness of CNS stimulants in patients with schizophrenia between 1995 and 2014; a mirror-image model with 605 individuals, using paired t tests and Wilcoxon signed rank tests, and a follow-up study with 789 individuals, using a conditional risk-set model. RESULTS: CNS...

  13. CNS metastasis from malignant uveal melanoma: a clinical and histopathological characterisation

    DEFF Research Database (Denmark)

    Holfort, S K; Lindegaard, J; Isager, P

    2008-01-01

    was observed in two cases (14%). The amount of tumour infiltrating lymphocytes was pronounced in three cases (23%). CONCLUSION: The proportion of uveal melanoma patients having CNS metastasis was 0.7%. Eleven patients had multiple organ metastases, and the average time from the initial CNS symptoms to death...

  14. 2D full wave simulation on electromagnetic wave propagation in toroidal plasma

    International Nuclear Information System (INIS)

    Hojo, Hitoshi; Uruta, Go; Nakayama, Kazunori; Mase, Atsushi

    2002-01-01

    Global full-wave simulation on electromagnetic wave propagation in toroidal plasma with an external magnetic field imaging a tokamak configuration is performed in two dimensions. The temporal behavior of an electromagnetic wave launched into plasma from a wave-guiding region is obtained. (author)

  15. HB-GAM (pleiotrophin) reverses inhibition of neural regeneration by the CNS extracellular matrix

    Science.gov (United States)

    Paveliev, Mikhail; Fenrich, Keith K.; Kislin, Mikhail; Kuja-Panula, Juha; Kulesskiy, Evgeny; Varjosalo, Markku; Kajander, Tommi; Mugantseva, Ekaterina; Ahonen-Bishopp, Anni; Khiroug, Leonard; Kulesskaya, Natalia; Rougon, Geneviève; Rauvala, Heikki

    2016-01-01

    Chondroitin sulfate (CS) glycosaminoglycans inhibit regeneration in the adult central nervous system (CNS). We report here that HB-GAM (heparin-binding growth-associated molecule; also known as pleiotrophin), a CS-binding protein expressed at high levels in the developing CNS, reverses the role of the CS chains in neurite growth of CNS neurons in vitro from inhibition to activation. The CS-bound HB-GAM promotes neurite growth through binding to the cell surface proteoglycan glypican-2; furthermore, HB-GAM abrogates the CS ligand binding to the inhibitory receptor PTPσ (protein tyrosine phosphatase sigma). Our in vivo studies using two-photon imaging of CNS injuries support the in vitro studies and show that HB-GAM increases dendrite regeneration in the adult cerebral cortex and axonal regeneration in the adult spinal cord. Our findings may enable the development of novel therapies for CNS injuries. PMID:27671118

  16. Therapy of CNS leukemia with intraventricular chemotherapy and low-dose neuraxis radiotherapy

    International Nuclear Information System (INIS)

    Steinherz, P.; Jereb, B.; Galicich, J.

    1985-01-01

    Successful treatment of CNS leukemic relapse has been frustrated by frequent local recurrence and eventual marrow relapse. The authors describe the treatment of meningeal leukemia in 39 children with intrathecal remission induction followed by the placement of an Ommaya reservoir to facilitate the administration and distribution of chemotherapeutic agents into the CSF. Six hundred or 900 rad of craniospinal radiation and maintenance intraventricular and intrathecal chemotherapy was then administered. Systemic reinduction therapy was added in the later cases. Sixteen children (41%) experienced no further events, with 17+ months to 13+ years (median, 25 months) follow-up . Eleven patients (28%) had CNS recurrence, nine (23%) bone marrow (BM) relapse, and two (5%) testicular relapse as the next adverse event. The course of patients with first isolated CNS relapse differed from that of the others. Eleven (69%) of 16 patients treated for first isolated CNS relapse are alive and 9 are event free, while only 35% of patients whose CNS relapse occurred simultaneously or after recurrent disease at other sites are alive (P = .04). Seven of 23 in the later group are event free. The difference is due to the increased incidence of BM relapse in the later group (30% v 6%; P = .04). For patients with first isolated CNS relapse, the life-table median CNS remission duration is 42 months. The projected CNS relapse-free survival and event-free survival 8 to 10 years after CNS relapse are 40% and 32%, respectively. Headache, nausea, and emesis of short duration were frequent during therapy. In three patients, the reservoir had to be removed for infection. No patient suffered neurologic deficit related to the reservoir. The therapy described can reduce the CNS relapse rate with manageable toxicity

  17. Lamb wave propagation in monocrystalline silicon wafers

    OpenAIRE

    Fromme, P.; Pizzolato, M.; Robyr, J-L; Masserey, B.

    2018-01-01

    Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. Guided ultrasonic waves offer the potential to efficiently detect micro-cracks in the thin wafers. Previous studies of ultrasonic wave propagation in silicon focused on effects of material anisotropy on bulk ultrasonic waves, but the dependence of the wave propagation characteristics on the material anisotropy is not well understood for Lamb waves. The phase slowness a...

  18. TIME COURSE MODIFICATIONS INDUCED BY PERINATAL ASPHYXIA IN RAT CNS

    Directory of Open Access Journals (Sweden)

    Francisco Capani

    2015-04-01

    of estradiol treatment we were able to revert some of these alterations using PI3K/Akt/GSK3. Overall these results demonstrate that synaptic dysfunction following PA might be produced by early changes in the actin organization and long-term misfolding and aggregation of proteins in the PSDs. Therefore, we hypothesize that the synaptic and neuronal cytoskeleton changes induced by PA in the rat CNS could lead to the cellular dysfunction and death in adult animals. Estradiol appears as a new therapeutic tool to slacken the damage induces by perinatal asphyxia on the CNS.

  19. Slow wave cyclotron maser

    International Nuclear Information System (INIS)

    Kho, T.H.; Lin, A.T.

    1988-01-01

    Cyclotron masers such as Gyrotrons and the Autoresonance Masers, are fast wave devices: the electromagnetic wave's phase velocity v rho , is greater than the electron beam velocity, v b . To be able to convert the beam kinetic energy into radiation in these devices the beam must have an initial transverse momentum, usually obtained by propagating the beam through a transverse wiggler magnet, or along a nonuniform guide magnetic field before entry into the interaction region. Either process introduces a significant amount of thermal spread in the beam which degrades the performance of the maser. However, if the wave phase velocity v rho v b , the beam kinetic energy can be converted directly into radiation without the requirement of an initial transverse beam momentum, making a slow wave cyclotron maser a potentially simpler and more compact device. The authors present the linear and nonlinear physics of the slow wave cyclotron maser and examine its potential for practical application

  20. Handbook of Ocean Wave Energy

    DEFF Research Database (Denmark)

    This book offers a concise, practice-oriented reference-guide to the field of ocean wave energy. The ten chapters highlight the key rules of thumb, address all the main technical engineering aspects and describe in detail all the key aspects to be considered in the techno-economic assessment...... in the wave energy sector. •Offers a practice-oriented reference guide to the field of ocean wave energy •Presents an overview as well as a deeper insight into wave energy converters •Covers both the economic and engineering aspects related to ocean wave energy conversion...... of wave energy converters. Written in an easy-to-understand style, the book answers questions relevant to readers of different backgrounds, from developers, private and public investors, to students and researchers. It is thereby a valuable resource for both newcomers and experienced practitioners...

  1. Handbook of Ocean Wave Energy

    DEFF Research Database (Denmark)

    This book offers a concise, practice-oriented reference-guide to the field of ocean wave energy. The ten chapters highlight the key rules of thumb, address all the main technical engineering aspects and describe in detail all the key aspects to be considered in the techno-economic assessment...... of wave energy converters. Written in an easy-to-understand style, the book answers questions relevant to readers of different backgrounds, from developers, private and public investors, to students and researchers. It is thereby a valuable resource for both newcomers and experienced practitioners...... in the wave energy sector. •Offers a practice-oriented reference guide to the field of ocean wave energy •Presents an overview as well as a deeper insight into wave energy converters •Covers both the economic and engineering aspects related to ocean wave energy conversion...

  2. 120 watt continuous wave solar-pumped laser with a liquid light-guide lens and an Nd:YAG rod.

    Science.gov (United States)

    Dinh, T H; Ohkubo, T; Yabe, T; Kuboyama, H

    2012-07-01

    We propose a simple and efficient pumping approach for a high-power solar-pumped laser by using a liquid light-guide lens (LLGL) and a hybrid pumping cavity. A 2×2 m Fresnel lens is used as a primary concentrator to collect natural sunlight; 120 W cw laser power and a 4.3% total slope efficiency are achieved with a 6-mm diameter Nd:YAG rod within a 14-mm diameter LLGL. The corresponded collection efficiency is 30.0 W/m(2), which is 1.5 times larger than the previous record. This result is unexpectedly better than that of Cr:Nd:YAG ceramics. It is because the scattering coefficient of Cr:Nd:YAG ceramics is 0.004cm(1), which is 2 times larger than that of the Nd:YAG crystal, although both have similar saturation gains.

  3. Legendre polynomial modeling for vibrations of guided Lamb waves modes in [001]c, [011]c and [111]c polarized (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (x = 0.29 and 0.33) piezoelectric plates: Physical phenomenon of multiple intertwining of An and Sn modes

    Science.gov (United States)

    Othmani, Cherif; Takali, Farid; Njeh, Anouar

    2017-12-01

    Guided wave devices have recently become one of the most important applications in the industry because such waves are directly related to applications in sensor technology, chemical sensing, agricultural science, fields of bio-sensing and surface acoustic wave (SAW) devices that are used in electronic filters and signal processing. On that account, this numerical investigation aims to study the propagation behavior of guided Lamb waves in a (1-x)Pb(Mg1/3Nb2/3)O3- x PbTiO3 [PMN- x PT] ( x=0.29 or 0.33) piezoelectric single crystal plate. In fact, the PMN- xPT ( x=0.29 or 0.33) piezoelectric crystals are being polarized along [001]c, [011]c and [111]c of the cubic reference directions so that the macroscopic symmetries are tetragonal 4 mm, orthogonal mm2 and rhombohedral 3 m, respectively. Both open- and short-circuit conditions are considered. Here, the Legendre polynomial method is proposed to solve the guided Lamb waves equations. The validity of the proposed method is illustrated by comparison with the ordinary differential equation (ODE). The convergence of this method is discussed. Consequently, the converged results are obtained with very low truncation order M . This constitutes a major advantage of the present method when compared with the other matrix methods. There is cross-crossings among multiple modes for both symmetric ( Sn) and the anti-symmetric ( An) guided Lamb waves propagation. A displacement field has been illustrated to judge whether Sn and An modes cross with each other. Moreover, electric displacement, stress field and electric potential for the open-circuit case were presented for both S0 and A0 Lamb modes.

  4. The Use of Flexible Ultrasound Transducers for the Detection of Laser-Induced Guided Waves on Curved Surfaces at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Tai Chieh Wu

    2017-06-01

    Full Text Available In this study, a flexible ultrasonic transducer (FUT was applied in a laser ultrasonic technique (LUT for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of a PZT/PZT sol-gel composite which has advantages due to its high sensitivity, curved surface adaptability and high temperature durability. By operating a pulsed laser in B-scan mode along with the integration of FUT and LUT, a multi-mode dispersion spectrum of a stainless steel pipe at high temperature can be measured. In addition, dynamic wave propagation behaviors are experimentally visualized with two dimensional scanning. The images directly interpret the reflections from the interior defects and also can locate their positions. This hybrid technique shows great potential for non-destructive evaluation of structures with complex geometry, especially in high temperature environments.

  5. Growth of Malignant Non-CNS Tumors Alters Brain Metabolome

    Science.gov (United States)

    Kovalchuk, Anna; Nersisyan, Lilit; Mandal, Rupasri; Wishart, David; Mancini, Maria; Sidransky, David; Kolb, Bryan; Kovalchuk, Olga

    2018-01-01

    Cancer survivors experience numerous treatment side effects that negatively affect their quality of life. Cognitive side effects are especially insidious, as they affect memory, cognition, and learning. Neurocognitive deficits occur prior to cancer treatment, arising even before cancer diagnosis, and we refer to them as “tumor brain.” Metabolomics is a new area of research that focuses on metabolome profiles and provides important mechanistic insights into various human diseases, including cancer, neurodegenerative diseases, and aging. Many neurological diseases and conditions affect metabolic processes in the brain. However, the tumor brain metabolome has never been analyzed. In our study we used direct flow injection/mass spectrometry (DI-MS) analysis to establish the effects of the growth of lung cancer, pancreatic cancer, and sarcoma on the brain metabolome of TumorGraft™ mice. We found that the growth of malignant non-CNS tumors impacted metabolic processes in the brain, affecting protein biosynthesis, and amino acid and sphingolipid metabolism. The observed metabolic changes were similar to those reported for neurodegenerative diseases and brain aging, and may have potential mechanistic value for future analysis of the tumor brain phenomenon. PMID:29515623

  6. Role of galectin-3 in prion infections of the CNS

    International Nuclear Information System (INIS)

    Mok, Simon W.F.; Riemer, Constanze; Madela, Kazimierz; Hsu, Daniel K.; Liu, Fu-Tong; Gueltner, Sandra; Heise, Ines; Baier, Michael

    2007-01-01

    Galectin-3 is a multi-functional protein and participates in mediating inflammatory reactions. The pronounced overexpression of galectin-3 in prion-infected brain tissue prompted us to study the role of this protein in a murine prion model. Immunofluorescence double-labelling identified microglia as the major cell type expressing galectin-3. Ablation of galectin-3 did not affect PrP Sc -deposition and development of gliosis. However, galectin-3 -/- -mice showed prolonged survival times upon intracerebral and peripheral scrapie infections. Moreover, protein levels of the lysosomal activation marker LAMP-2 were markedly reduced in prion-infected galectin-3 -/- -mice suggesting a role of galectin-3 in regulation of lysosomal functions. Lower mRNA levels of Beclin-1 and Atg5 in prion-infected wild-type and galectin-3 -/- -mice indicated an impairment of autophagy although autophagosome formation was unchanged. The results point towards a detrimental role of galectin-3 in prion infections of the CNS and suggest that endo-/lysosomal dysfunction in combination with reduced autophagy may contribute to disease development

  7. Fluids and barriers of the CNS: a historical viewpoint

    Directory of Open Access Journals (Sweden)

    Liddelow Shane A

    2011-01-01

    Full Text Available Abstract Tracing the exact origins of modern science can be a difficult but rewarding pursuit. It is possible for the astute reader to follow the background of any subject through the many important surviving texts from the classical and ancient world. While empirical investigations have been described by many since the time of Aristotle and scientific methods have been employed since the Middle Ages, the beginnings of modern science are generally accepted to have originated during the 'scientific revolution' of the 16th and 17th centuries in Europe. The scientific method is so fundamental to modern science that some philosophers consider earlier investigations as 'pre-science'. Notwithstanding this, the insight that can be gained from the study of the beginnings of a subject can prove important in the understanding of work more recently completed. As this journal undergoes an expansion in focus and nomenclature from cerebrospinal fluid (CSF into all barriers of the central nervous system (CNS, this review traces the history of both the blood-CSF and blood-brain barriers from as early as it was possible to find references, to the time when modern concepts were established at the beginning of the 20th century.

  8. CNS fungal meningitis to the "Top of the basilar"

    Institute of Scientific and Technical Information of China (English)

    Logan CS; Kirschner RC; Simonds GR

    2013-01-01

    Central nervous system(CNS) infections are a rare complication of epidural steroid injections and without strong clinical suspicion, fungal organisms may be overlooked among the long differential of causes of meningitis.Rare sequela of fungal meningitis is the development of stroke.To our knowledge, we present the first case of post epidural steroid injection(ESI) fungal meningitis leading toa basilar artery stroke, otherwise known as“top of the basilar” syndrome.We present a49-year-old female with a history ofESIs who presented to the emergency department with headache, neck stiffness, and abdominal pain.She was discharged after her labs and symptoms were deemed inconsistent with meningitis.She was eventually admitted and twelve days after her originalED visit, she was diagnosed with meningitis and started on anti-fungal treatment.She was discharged88 days later but was readmitted due to left sided weakness and mental status changes.She quickly lost motor and bulbar functions.AnMRA showed diminished distal flow through the basilar artery, suggesting near complete occlusion.Although appropriate long term anti-fungal treatment was started, the patient still succumbed to a rare vascular event.Physicians who are treating patients forESI meningitis should be aware of the potential for vasculitic and encephalitic complications.

  9. Stress preconditioning of spreading depression in the locust CNS.

    Directory of Open Access Journals (Sweden)

    Corinne I Rodgers

    Full Text Available Cortical spreading depression (CSD is closely associated with important pathologies including stroke, seizures and migraine. The mechanisms underlying SD in its various forms are still incompletely understood. Here we describe SD-like events in an invertebrate model, the ventilatory central pattern generator (CPG of locusts. Using K(+ -sensitive microelectrodes, we measured extracellular K(+ concentration ([K(+](o in the metathoracic neuropile of the CPG while monitoring CPG output electromyographically from muscle 161 in the second abdominal segment to investigate the role K(+ in failure of neural circuit operation induced by various stressors. Failure of ventilation in response to different stressors (hyperthermia, anoxia, ATP depletion, Na(+/K(+ ATPase impairment, K(+ injection was associated with a disturbance of CNS ion homeostasis that shares the characteristics of CSD and SD-like events in vertebrates. Hyperthermic failure was preconditioned by prior heat shock (3 h, 45 degrees C and induced-thermotolerance was associated with an increase in the rate of clearance of extracellular K(+ that was not linked to changes in ATP levels or total Na(+/K(+ ATPase activity. Our findings suggest that SD-like events in locusts are adaptive to terminate neural network operation and conserve energy during stress and that they can be preconditioned by experience. We propose that they share mechanisms with CSD in mammals suggesting a common evolutionary origin.

  10. Human abuse liability evaluation of CNS stimulant drugs.

    Science.gov (United States)

    Romach, Myroslava K; Schoedel, Kerri A; Sellers, Edward M

    2014-12-01

    Psychoactive drugs that increase alertness, attention and concentration and energy, while also elevating mood, heart rate and blood pressure are referred to as stimulants. Despite some overlapping similarities, stimulants cannot be easily categorized by their chemical structure, mechanism of action, receptor binding profile, effects on monoamine uptake, behavioral pharmacology (e.g., effects on locomotion, temperature, and blood pressure), therapeutic indication or efficacy. Because of their abuse liability, a pre-market assessment of abuse potential is required for drugs that show stimulant properties; this review article focuses on the clinical aspects of this evaluation. This includes clinical trial adverse events, evidence of diversion or tampering, overdoses and the results of a human abuse potential study. While there are different types of human experimental studies that can be employed to evaluate stimulant abuse potential (e.g., drug discrimination, self-administration), only the human abuse potential study and clinical trial adverse event data are required for drug approval. The principal advances that have improved human abuse potential studies include using study enrichment strategies (pharmacologic qualification), larger sample sizes, better selection of endpoints and measurement strategies and more carefully considered interpretation of data. Because of the methodological advances, comparisons of newer studies with historical data is problematic and may contribute to a biased regulatory framework for the evaluation of newer stimulant-like drugs, such as A2 antagonists. This article is part of the Special Issue entitled 'CNS Stimulants'. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. The mastermind approach to CNS drug therapy: translational prediction of human brain distribution, target site kinetics, and therapeutic effects

    OpenAIRE

    de Lange, Elizabeth CM

    2013-01-01

    Despite enormous advances in CNS research, CNS disorders remain the world?s leading cause of disability. This accounts for more hospitalizations and prolonged care than almost all other diseases combined, and indicates a high unmet need for good CNS drugs and drug therapies. Following dosing, not only the chemical properties of the drug and blood?brain barrier (BBB) transport, but also many other processes will ultimately determine brain target site kinetics and consequently the CNS effects. ...

  12. When the Tail Can't Wag the Dog: The Implications of CNS-Intrinsic Initiation of Neuroinflammation

    Directory of Open Access Journals (Sweden)

    Deirdre S Davis

    2009-04-01

    Full Text Available The CNS (central nervous system is unquestionably the central organ that regulates directly or indirectly all physiological systems in the mammalian body. Yet, when considering the defence of the CNS from pathogens, the CNS has often been considered passive and subservient to the pro-inflammatory responses of the immune system. In this view, neuroinflammatory disorders are examples of when the tail (the immune system wags the dog (the CNS to the detriment of an individual's function and survival.

  13. The retina as a window to the brain-from eye research to CNS disorders.

    Science.gov (United States)

    London, Anat; Benhar, Inbal; Schwartz, Michal

    2013-01-01

    Philosophers defined the eye as a window to the soul long before scientists addressed this cliché to determine its scientific basis and clinical relevance. Anatomically and developmentally, the retina is known as an extension of the CNS; it consists of retinal ganglion cells, the axons of which form the optic nerve, whose fibres are, in effect, CNS axons. The eye has unique physical structures and a local array of surface molecules and cytokines, and is host to specialized immune responses similar to those in the brain and spinal cord. Several well-defined neurodegenerative conditions that affect the brain and spinal cord have manifestations in the eye, and ocular symptoms often precede conventional diagnosis of such CNS disorders. Furthermore, various eye-specific pathologies share characteristics of other CNS pathologies. In this Review, we summarize data that support examination of the eye as a noninvasive approach to the diagnosis of select CNS diseases, and the use of the eye as a valuable model to study the CNS. Translation of eye research to CNS disease, and deciphering the role of immune cells in these two systems, could improve our understanding and, potentially, the treatment of neurodegenerative disorders.

  14. Observations at the CNS-PNS border of ventral roots connected to a neuroma

    Directory of Open Access Journals (Sweden)

    Sten Remahl

    2010-10-01

    Full Text Available Previous studies have shown that numerous sprouts originating from a neuroma, after nerve injury in neonatal animals, can invade spinal nerve roots. In this study the border between the central and peripheral nervous system (CNS-PNS border of ventral roots in kittens was examined with both light and electron microscopy after early postnatal sciatic nerve resection. A transient ingrowth of substance P positive axons was observed into the CNS, but no spouts remained 6 weeks after the injury. Using serial sections and electron microscopy it was possible to identify small bundles of unmyelinated axons that penetrated from the root fascicles for a short distance into the CNS. These axons ended blindly, sometimes with a growth cone-like terminal swelling filled with vesicles. The axon bundles were accompanied by p75 positive cells in both the root fascicles and the pia mater, but not in the CNS. It may thus be suggested that neurotrophin presenting p75 positive cells could facilitate axonal growth into the pia mater and that the lack of such cells in the CNS compartment might contribute to the failure of growth into the CNS. A maldevelopment of myelin sheaths at the CNS-PNS border of motor axons was observed and it seems possible that this could have consequences for the propagation of action potential across this region after neonatal nerve injury.

  15. Glucocorticoid treatment of MCMV infected newborn mice attenuates CNS inflammation and limits deficits in cerebellar development.

    Directory of Open Access Journals (Sweden)

    Kate Kosmac

    2013-03-01

    Full Text Available Infection of the developing fetus with human cytomegalovirus (HCMV is a major cause of central nervous system disease in infants and children; however, mechanism(s of disease associated with this intrauterine infection remain poorly understood. Utilizing a mouse model of HCMV infection of the developing CNS, we have shown that peripheral inoculation of newborn mice with murine CMV (MCMV results in CNS infection and developmental abnormalities that recapitulate key features of the human infection. In this model, animals exhibit decreased granule neuron precursor cell (GNPC proliferation and altered morphogenesis of the cerebellar cortex. Deficits in cerebellar cortical development are symmetric and global even though infection of the CNS results in a non-necrotizing encephalitis characterized by widely scattered foci of virus-infected cells with mononuclear cell infiltrates. These findings suggested that inflammation induced by MCMV infection could underlie deficits in CNS development. We investigated the contribution of host inflammatory responses to abnormal cerebellar development by modulating inflammatory responses in infected mice with glucocorticoids. Treatment of infected animals with glucocorticoids decreased activation of CNS mononuclear cells and expression of inflammatory cytokines (TNF-α, IFN-β and IFNγ in the CNS while minimally impacting CNS virus replication. Glucocorticoid treatment also limited morphogenic abnormalities and normalized the expression of developmentally regulated genes within the cerebellum. Importantly, GNPC proliferation deficits were normalized in MCMV infected mice following glucocorticoid treatment. Our findings argue that host inflammatory responses to MCMV infection contribute to deficits in CNS development in MCMV infected mice and suggest that similar mechanisms of disease could be responsible for the abnormal CNS development in human infants infected in-utero with HCMV.

  16. Spontaneous calcium waves in granule cells in cerebellar slice cultures

    DEFF Research Database (Denmark)

    Apuschkin, Mia; Ougaard, Maria; Rekling, Jens C

    2013-01-01

    Multiple regions in the CNS display propagating correlated activity during embryonic and postnatal development. This activity can be recorded as waves of increased calcium concentrations in spiking neurons or glia cells, and have been suggested to be involved in patterning, axonal guidance and es......, that the propagating wave activity is carried through the tissue by axonal collaterals formed by neighboring granule cells, and further suggest that the correlated activity may be related to processes that ensure correct postnatal wiring of the cerebellar circuits....

  17. 25th Annual Computational Neuroscience Meeting: CNS-2016

    OpenAIRE

    Sharpee, Tatyana O.; Destexhe, Alain; Kawato, Mitsuo; Sekulić, Vladislav; Skinner, Frances K.; Wójcik, Daniel K.; Chintaluri, Chaitanya; Cserpán, Dorottya; Somogyvári, Zoltán; Kim, Jae Kyoung; Kilpatrick, Zachary P.; Bennett, Matthew R.; Josić, Kresimir; Elices, Irene; Arroyo, David

    2016-01-01

    Table of contents A1 Functional advantages of cell-type heterogeneity in neural circuits Tatyana O. Sharpee A2 Mesoscopic modeling of propagating waves in visual cortex Alain Destexhe A3 Dynamics and biomarkers of mental disorders Mitsuo Kawato F1 Precise recruitment of spiking output at theta frequencies requires dendritic h-channels in multi-compartment models of oriens-lac...

  18. Carbon monoxide inhalation increases microparticles causing vascular and CNS dysfunction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jiajun; Yang, Ming [Department of Emergency Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States); Kosterin, Paul [Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States); Salzberg, Brian M. [Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States); Milovanova, Tatyana N.; Bhopale, Veena M. [Department of Emergency Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States); Thom, Stephen R., E-mail: sthom@smail.umaryland.edu [Department of Emergency Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States)

    2013-12-01

    We hypothesized that circulating microparticles (MPs) play a role in pro-inflammatory effects associated with carbon monoxide (CO) inhalation. Mice exposed for 1 h to 100 ppm CO or more exhibit increases in circulating MPs derived from a variety of vascular cells as well as neutrophil activation. Tissue injury was quantified as 2000 kDa dextran leakage from vessels and as neutrophil sequestration in the brain and skeletal muscle; and central nervous system nerve dysfunction was documented as broadening of the neurohypophysial action potential (AP). Indices of injury occurred following exposures to 1000 ppm for 1 h or to 1000 ppm for 40 min followed by 3000 ppm for 20 min. MPs were implicated in causing injuries because infusing the surfactant MP lytic agent, polyethylene glycol telomere B (PEGtB) abrogated elevations in MPs, vascular leak, neutrophil sequestration and AP prolongation. These manifestations of tissue injury also did not occur in mice lacking myeloperoxidase. Vascular leakage and AP prolongation were produced in naïve mice infused with MPs that had been obtained from CO poisoned mice, but this did not occur with MPs obtained from control mice. We conclude that CO poisoning triggers elevations of MPs that activate neutrophils which subsequently cause tissue injuries. - Highlights: • Circulating microparticles (MPs) increase in mice exposed to 100 ppm CO or more. • MPs are lysed by infusing the surfactant polyethylene glycol telomere B. • CO-induced MPs cause neutrophil activation, vascular leak and CNS dysfunction. • Similar tissue injuries do not arise with MPs obtained from air-exposed, control mice.

  19. Short- to mid-term follow-up effectiveness of US-guided focal extracorporeal shock wave therapy in the treatment of elbow lateral epicondylitis.

    Science.gov (United States)

    Trentini, R; Mangano, T; Repetto, I; Cerruti, P; Kuqi, E; Trompetto, C; Franchin, F

    2015-09-01

    Lateral epicondylitis of the elbow is a common and disabling overuse syndrome. Several treatment modalities are currently available for this condition, but the optimal treatment method remains undefined. Extracorporeal shock wave therapy (ESWT) has been widely used in the last 10 years, although conflicting results are present in the literature. In this study, we evaluated 36 patients (37 elbows), with a mean follow-up time of 24.8 months. Focal ESWT was administered by means of an electromagnetic generator equipped with in-line ultrasound guidance, during one or more cycles of 3-4 weekly sessions. In the setting of the study, patients were clinically evaluated and subjective satisfaction and rate of relapse were investigated. A positive response was described in 75.7 % of the patients after treatment. Mean quickDASH score and VAS attested at 5.5 and 1.1, respectively. Roles and Maudsley score was rated as I or II in 33 cases. Four patients resulted not responders to the therapy, while 5 patients complained one or more episodes of symptoms relapse. No influence on the final outcome was evident with respect to demographic features and previous therapies as well. Response rate to further ESWT cycles in patients refractory to the first cycle of ESWT was 33.3 %. Focal ESWT represents a valuable and safe solution in case of elbow lateral epicondylitis, both in newly diagnosed and previously treated cases, representing a definitive treatment in the majority of patients. Patients refractory to a 3- to 4-session ESWT cycle have lower chances of positive response after further ESWT cycles.

  20. CLIPPERS among patients diagnosed with non-specific CNS neuroinflammatory diseases

    DEFF Research Database (Denmark)

    Kerrn-Jespersen, B M; Lindelof, M; Illes, Zsolt

    2014-01-01

    Chronic Lymphocytic Inflammation with Pontine Perivascular Enhancement Responsive to Steroids (CLIPPERS) is an inflammatory CNS disorder characterized by 1) subacute onset of cerebellar and brainstem symptoms, 2) peripontine contrast-enhancing perivascular lesions with a "salt-and-pepper" appeara...

  1. New Brain Tumor Entities Emerge from Molecular Classification of CNS-PNETs

    NARCIS (Netherlands)

    Sturm, Dominik; Orr, Brent A.; Toprak, Umut H.; Hovestadt, Volker; Jones, David T. W.; Capper, David; Sill, Martin; Buchhalter, Ivo; Northcott, Paul A.; Leis, Irina; Ryzhova, Marina; Koelsche, Christian; Pfaff, Elke; Allen, Sariah J.; Balasubramanian, Gnanaprakash; Worst, Barbara C.; Pajtler, Kristian W.; Brabetz, Sebastian; Johann, Pascal D.; Sahm, Felix; Reimand, Jüri; Mackay, Alan; Carvalho, Diana M.; Remke, Marc; Phillips, Joanna J.; Perry, Arie; Cowdrey, Cynthia; Drissi, Rachid; Fouladi, Maryam; Giangaspero, Felice; Łastowska, Maria; Grajkowska, Wiesława; Scheurlen, Wolfram; Pietsch, Torsten; Hagel, Christian; Gojo, Johannes; Lötsch, Daniela; Berger, Walter; Slavc, Irene; Haberler, Christine; Jouvet, Anne; Holm, Stefan; Hofer, Silvia; Prinz, Marco; Keohane, Catherine; Fried, Iris; Mawrin, Christian; Scheie, David; Mobley, Bret C.; Schniederjan, Matthew J.; Santi, Mariarita; Buccoliero, Anna M.; Dahiya, Sonika; Kramm, Christof M.; von Bueren, André O.; von Hoff, Katja; Rutkowski, Stefan; Herold-Mende, Christel; Frühwald, Michael C.; Milde, Till; Hasselblatt, Martin; Wesseling, Pieter; Rößler, Jochen; Schüller, Ulrich; Ebinger, Martin; Schittenhelm, Jens; Frank, Stephan; Grobholz, Rainer; Vajtai, Istvan; Hans, Volkmar; Schneppenheim, Reinhard; Zitterbart, Karel; Collins, V. Peter; Aronica, Eleonora; Varlet, Pascale; Puget, Stephanie; Dufour, Christelle; Grill, Jacques; Figarella-Branger, Dominique; Wolter, Marietta; Schuhmann, Martin U.; Shalaby, Tarek; Grotzer, Michael; van Meter, Timothy; Monoranu, Camelia-Maria; Felsberg, Jörg; Reifenberger, Guido; Snuderl, Matija; Forrester, Lynn Ann; Koster, Jan; Versteeg, Rogier; Volckmann, Richard; van Sluis, Peter; Wolf, Stephan; Mikkelsen, Tom; Gajjar, Amar; Aldape, Kenneth; Moore, Andrew S.; Taylor, Michael D.; Jones, Chris; Jabado, Nada; Karajannis, Matthias A.; Eils, Roland; Schlesner, Matthias; Lichter, Peter; von Deimling, Andreas; Pfister, Stefan M.; Ellison, David W.; Korshunov, Andrey; Kool, Marcel

    2016-01-01

    Primitive neuroectodermal tumors of the central nervous system (CNS-PNETs) are highly aggressive, poorly differentiated embryonal tumors occurring predominantly in young children but also affecting adolescents and adults. Herein, we demonstrate that a significant proportion of institutionally

  2. New Brain Tumor Entities Emerge from Molecular Classification of CNS-PNETs

    NARCIS (Netherlands)

    Sturm, Dominik; Orr, Brent A.; Toprak, Umut H.; Hovestadt, Volker; Jones, David T W; Capper, David; Sill, Martin; Buchhalter, Ivo; Northcott, Paul A.; Leis, Irina; Ryzhova, Marina; Koelsche, Christian; Pfaff, Elke; Allen, Sariah J.; Balasubramanian, Gnanaprakash; Worst, Barbara C.; Pajtler, Kristian W.; Brabetz, Sebastian; Johann, Pascal D.; Sahm, Felix; Reimand, Jüri; Mackay, Alan; Carvalho, Diana M.; Remke, Marc; Phillips, Joanna J.; Perry, Arie; Cowdrey, Cynthia; Drissi, Rachid; Fouladi, Maryam; Giangaspero, Felice; Łastowska, Maria; Grajkowska, Wiesława; Scheurlen, Wolfram; Pietsch, Torsten; Hagel, Christian; Gojo, Johannes; Lötsch, Daniela; Berger, Walter; Slavc, Irene; Haberler, Christine; Jouvet, Anne; Holm, Stefan; Hofer, Silvia; Prinz, Marco; Keohane, Catherine; Fried, Iris; Mawrin, Christian; Scheie, David; Mobley, Bret C.; Schniederjan, Matthew J.; Santi, Mariarita; Buccoliero, Anna M.; Dahiya, Sonika; Kramm, Christof M.; Von Bueren, André O.; Von Hoff, Katja; Rutkowski, Stefan; Herold-Mende, Christel; Frühwald, Michael C.; Milde, Till; Hasselblatt, Martin; Wesseling, Pieter; Rößler, Jochen; Schüller, Ulrich; Ebinger, Martin; Schittenhelm, Jens; Frank, Stephan; Grobholz, Rainer; Vajtai, Istvan; Hans, Volkmar; Schneppenheim, Reinhard; Zitterbart, Karel; Collins, V. Peter; Aronica, Eleonora; Varlet, Pascale; Puget, Stephanie; Dufour, Christelle; Grill, Jacques; Figarella-Branger, Dominique; Wolter, Marietta; Schuhmann, Martin U.; Shalaby, Tarek; Grotzer, Michael; Van Meter, Timothy; Monoranu, Camelia Maria; Felsberg, Jörg; Reifenberger, Guido; Snuderl, Matija; Forrester, Lynn Ann; Koster, Jan; Versteeg, Rogier; Volckmann, Richard; Van Sluis, Peter; Wolf, Stephan; Mikkelsen, Tom; Gajjar, Amar; Aldape, Kenneth; Moore, Andrew S.; Taylor, Michael D.; Jones, Chris; Jabado, Nada; Karajannis, Matthias A.; Eils, Roland; Schlesner, Matthias; Lichter, Peter; Von Deimling, Andreas; Pfister, Stefan M.; Ellison, David W.; Korshunov, Andrey; Kool, Marcel

    2016-01-01

    Summary Primitive neuroectodermal tumors of the central nervous system (CNS-PNETs) are highly aggressive, poorly differentiated embryonal tumors occurring predominantly in young children but also affecting adolescents and adults. Herein, we demonstrate that a significant proportion of

  3. Netrin-1 Confines Rhombic Lip-Derived Neurons to the CNS

    Directory of Open Access Journals (Sweden)

    Andrea R. Yung

    2018-02-01

    Full Text Available During brainstem development, newborn neurons originating from the rhombic lip embark on exceptionally long migrations to generate nuclei important for audition, movement, and respiration. Along the way, this highly motile population passes several cranial nerves yet remains confined to the CNS. We found that Ntn1 accumulates beneath the pial surface separating the CNS from the PNS, with gaps at nerve entry sites. In mice null for Ntn1 or its receptor DCC, hindbrain neurons enter cranial nerves and migrate into the periphery. CNS neurons also escape when Ntn1 is selectively lost from the sub-pial region (SPR, and conversely, expression of Ntn1 throughout the mutant hindbrain can prevent their departure. These findings identify a permissive role for Ntn1 in maintaining the CNS-PNS boundary. We propose that Ntn1 confines rhombic lip-derived neurons by providing a preferred substrate for tangentially migrating neurons in the SPR, preventing their entry into nerve roots.

  4. Micropituitarism and cortical dysplasia: an unknown association of two uncommon CNS disorders

    International Nuclear Information System (INIS)

    Blinder, G.; Corat-Simon, J.; Hershkovitz, E.

    2001-01-01

    We describe a case of two known pathologies of the CNS in an unusual association: the concomitant presentation of the micropituitarism and cortical dysplasia. To our knowledge, this association is unreported to date. (orig.)

  5. Micropituitarism and cortical dysplasia: an unknown association of two uncommon CNS disorders

    Energy Technology Data Exchange (ETDEWEB)

    Blinder, G. [MAR Bikur Cholim Hospital Jerusalem (MOR-MAR), Jerusalem (Israel); Corat-Simon, J. [Dept. of Radiology, Assaf Harofeh Medical Center, Zrifin, Beer Jakov (Israel); Hershkovitz, E. [Dept. of Pediatrics, Soroka Medical Center, Beer Sheba (Israel)

    2001-06-01

    We describe a case of two known pathologies of the CNS in an unusual association: the concomitant presentation of the micropituitarism and cortical dysplasia. To our knowledge, this association is unreported to date. (orig.)

  6. Instantaneous wave emission model

    International Nuclear Information System (INIS)

    Kruer, W.L.

    1970-12-01

    A useful treatment of electrostatic wave emission by fast particles in a plasma is given. First, the potential due to a fast particle is expressed as a simple integration over the particle orbit; several interesting results readily follow. The potential in the wake of an accelerating particle is shown to be essentially that produced through local excitation of the plasma by the particle free-streaming about its instantaneous orbit. Application is made to one dimension, and it is shown that the wave emission and adsorption synchronize to the instantaneous velocity distribution function. Guided by these calculations, we then formulate a test particle model for computing the instantaneous wave emission by fast particles in a Vlasov plasma. This model lends itself to physical interpretation and provides a direct approach to many problems. By adopting a Fokker-Planck description for the particle dynamics, we calculate the broadening of the wave-particle resonance due to velocity diffusion and drag

  7. Drug induced increases in CNS dopamine alter monocyte, macrophage and T cell functions: implications for HAND

    Science.gov (United States)

    Gaskill, Peter J.; Calderon, Tina M.; Coley, Jacqueline S.; Berman, Joan W.

    2013-01-01

    Central nervous system (CNS) complications resulting from HIV infection remain a major public health problem as individuals live longer due to the success of combined antiretroviral therapy (cART). As many as 70% of HIV infected people have HIV associated neurocognitive disorders (HAND). Many HIV infected individuals abuse drugs, such as cocaine, heroin or methamphetamine, that may be important cofactors in the development of HIV CNS disease. Despite different mechanisms of action, all drugs of abuse increase extracellular dopamine in the CNS. The effects of dopamine on HIV neuropathogenesis are not well understood, and drug induced increases in CNS dopamine may be a common mechanism by which different types of drugs of abuse impact the development of HAND. Monocytes and macrophages are central to HIV infection of the CNS and to HAND. While T cells have not been shown to be a major factor in HIV-associated neuropathogenesis, studies indicate that T cells may play a larger role in the development of HAND in HIV infected drug abusers. Drug induced increases in CNS dopamine may dysregulate functions of, or increase HIV infection in, monocytes, macrophages and T cells in the brain. Thus, characterizing the effects of dopamine on these cells is important for understanding the mechanisms that mediate the development of HAND in drug abusers. PMID:23456305

  8. Newnes short wave listening handbook

    CERN Document Server

    Pritchard, Joe

    2013-01-01

    Newnes Short Wave Listening Handbook is a guide for starting up in short wave listening (SWL). The book is comprised of 15 chapters that discuss the basics and fundamental concepts of short wave radio listening. The coverage of the text includes electrical principles; types of signals that can be heard in the radio spectrum; and using computers in SWL. The book also covers SWL equipment, such as receivers, converters, and circuits. The text will be of great use to individuals who want to get into short wave listening.

  9. Gain factors with the new supermirror guide system at the Budapest Neutron Centre

    International Nuclear Information System (INIS)

    Rosta, L.; Cser, L.; Revay, Z.

    2002-01-01

    In parallel with the installation of a cold-neutron source (CNS) at the 10-MW Budapest Research Reactor, the neutron-guide system has been redesigned and replaced by state of art neutron optical elements. Monte Carlo calculations have been used to determine the optimal conditions for the guide parameters. For the three cold-neutron beams nearly 100 m of new guides were installed; a great part is made of supermirrors. The new in-pile guide system and the individual shutters enable minimal losses at the starting sections. The out-of-pile part was optimized for the experimental stations. The neutron-flux measurements were compared with the simulated values. The combined effect of the CNS and the guide system yields a gain factor in the flux as high as 30-60. (orig.)

  10. Attenuation Analysis of Lamb Waves Using the Chirplet Transform

    NARCIS (Netherlands)

    Kerber, Florian; Sprenger, Helge; Niethammer, Marc; Luangvilai, Kritsakorn; Jacobs, Laurence J.

    2010-01-01

    Guided Lamb waves are commonly used in nondestructive evaluation to monitor plate-like structures or to characterize properties of composite or layered materials. However, the dispersive propagation and multimode excitability of Lamb waves complicate their analysis. Advanced signal processing

  11. Shock-induced borehole waves and fracture effects

    NARCIS (Netherlands)

    Fan, H.; Smeulders, D.M.J.

    2012-01-01

    We perform wave experiments using a vertical shock tube setup. Shock waves are generated by the rupture of a thin membrane. In the test section the incident pressure waves generate borehole-guided waves along water-saturated samples. The tube is equipped with side wall gages and a mobile pressure

  12. Facile one-pot transformation using structure-guided combustion waves of micro-nanostructured β-Bi2O3 to α-Bi2O3@C and analysis of electrochemical capacitance

    Science.gov (United States)

    Hwang, Hayoung; Shin, Jung-ho; Lee, Kang Yeol; Choi, Wonjoon

    2018-01-01

    Precise phase-transformation can facilitate control of the properties of various materials, while an organic coating surrounding inorganic materials can yield useful characteristics. Herein, we demonstrate facile, selective manipulation of micro-nanostructured bismuth oxide (Bi2O3) for phase transformation from microflower-like β-Bi2O3 to micropill-like α-Bi2O3, with carbon-coating layer deposition, using structure-guided combustion waves (SGCWs). Microflower-like β-Bi2O3 are synthesized as core materials and nitrocellulose is coated on their surfaces for the formation of core-shell hybrid structures of Bi2O3 and chemical fuel. The SGCWs, which propagate along the core-material and fuel interfaces, apply high thermal energy (550-600 °C) and deposit incompletely combusted carbonaceous fuel on the microflower-like β-Bi2O3 to enable transformation to α-phase and carbon-coating-layer synthesis. SGCW-induced improvements to the electrochemical characteristics of the developed micropill-like α-Bi2O3@C, compared with the microflower-like β-Bi2O3, are investigated. The enhanced stability from the α-phase Bi2O3 and micropill-like structures during charge-discharge cycling improves the specific capacitance, while the carbon-coating layers facilitate increased electrical conductivity. SGCW-based methods exhibit high potential for selective phase manipulation and synthesis of carbon coatings surrounding micro-nanomaterials. They constitute a low-cost, fast, large-scale process for metal oxides, ceramics, and hybrid materials, implemented through control of the processing parameters by tuning the temperature, chemical fuel, and ambient conditions.

  13. CNS involvement in AIDS: spectrum of CT and MR findings

    International Nuclear Information System (INIS)

    Thurnher, M.M.; Thurnher, S.A.; Schindler, E.

    1997-01-01

    The brain may be affected by a variety of abnormalities in association with human immunodeficiency virus (HIV) infection. Knowledge of their existence and characteristic imaging features are important to radiologists for detection, diagnosis, and initiation of an appropriate treatment. Although there is a considerable overlap in the imaging characteristics of different entities, some findings are found to be very suggestive of a particular disease. The CT and MR imaging techniques are commonly used in the diagnosis of neurological disorders in acquired immunodeficiency syndrome (AIDS) patients, to verify treatment response and to guide brain biopsy. This review attempts to describe CT and MR features of infectious and malignant brain disorders in HIV-seropositive patients. (orig.). With 13 figs

  14. Contribution of Schwann Cells to Remyelination in a Naturally Occurring Canine Model of CNS Neuroinflammation.

    Directory of Open Access Journals (Sweden)

    Kristel Kegler

    Full Text Available Gliogenesis under pathophysiological conditions is of particular clinical relevance since it may provide evidence for regeneration promoting cells recruitable for therapeutic purposes. There is evidence that neurotrophin receptor p75 (p75NTR-expressing cells emerge in the lesioned CNS. However, the phenotype and identity of these cells, and signals triggering their in situ generation under normal conditions and certain pathological situations has remained enigmatic. In the present study, we used a spontaneous, idiopathic and inflammatory CNS condition in dogs with prominent lympho-histiocytic infiltration as a model to study the phenotype of Schwann cells and their relation to Schwann cell remyelination within the CNS. Furthermore, the phenotype of p75NTR-expressing cells within the injured CNS was compared to their counter-part in control sciatic nerve and after peripheral nerve injury. In addition, organotypic slice cultures were used to further elucidate the origin of p75NTR-positive cells. In cerebral and cerebellar white and grey matter lesions as well as in the brain stem, p75NTR-positive cells co-expressed the transcription factor Sox2, but not GAP-43, GFAP, Egr2/Krox20, periaxin and PDGFR-α. Interestingly, and contrary to the findings in control sciatic nerves, p75NTR-expressing cells only co-localized with Sox2 in degenerative neuropathy, thus suggesting that such cells might represent dedifferentiated Schwann cells both in the injured CNS and PNS. Moreover, effective Schwann cell remyelination represented by periaxin- and P0-positive mature myelinating Schwann cells, was strikingly associated with the presence of p75NTR/Sox2-expressing Schwann cells. Intriguingly, the emergence of dedifferentiated Schwann cells was not affected by astrocytes, and a macrophage-dominated inflammatory response provided an adequate environment for Schwann cells plasticity within the injured CNS. Furthermore, axonal damage was reduced in brain stem areas

  15. CNS infiltration of peripheral immune cells: D-Day for neurodegenerative disease?

    Science.gov (United States)

    Rezai-Zadeh, Kavon; Gate, David; Town, Terrence

    2009-12-01

    While the central nervous system (CNS) was once thought to be excluded from surveillance by immune cells, a concept known as "immune privilege," it is now clear that immune responses do occur in the CNS-giving rise to the field of neuroimmunology. These CNS immune responses can be driven by endogenous (glial) and/or exogenous (peripheral leukocyte) sources and can serve either productive or pathological roles. Recent evidence from mouse models supports the notion that infiltration of peripheral monocytes/macrophages limits progression of Alzheimer's disease pathology and militates against West Nile virus encephalitis. In addition, infiltrating T lymphocytes may help spare neuronal loss in models of amyotrophic lateral sclerosis. On the other hand, CNS leukocyte penetration drives experimental autoimmune encephalomyelitis (a mouse model for the human demyelinating disease multiple sclerosis) and may also be pathological in both Parkinson's disease and human immunodeficiency virus encephalitis. A critical understanding of the cellular and molecular mechanisms responsible for trafficking of immune cells from the periphery into the diseased CNS will be key to target these cells for therapeutic intervention in neurodegenerative diseases, thereby allowing neuroregenerative processes to ensue.

  16. Current approaches to enhance CNS delivery of drugs across the brain barriers

    Directory of Open Access Journals (Sweden)

    Lu CT

    2014-05-01

    Full Text Available Cui-Tao Lu,1 Ying-Zheng Zhao,2,3 Ho Lun Wong,4 Jun Cai,5 Lei Peng,2 Xin-Qiao Tian1 1The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou City, Zhejiang Province, People’s Republic of China; 2Hainan Medical College, Haikou City, Hainan Province, People’s Republic of China; 3College of Pharmaceutical Sciences, Wenzhou Medical University, Zhejiang Province, People’s Republic of China; 4School of Pharmacy, Temple University, Philadelphia, PA, USA; 5Departments of Pediatrics and Anatomical Sciences and Neurobiology, University of Louisville School of Medicine Louisville, KY, USA Abstract: Although many agents have therapeutic potentials for central nervous system (CNS diseases, few of these agents have been clinically used because of the brain barriers. As the protective barrier of the CNS, the blood–brain barrier and the blood–cerebrospinal fluid barrier maintain the brain microenvironment, neuronal activity, and proper functioning of the CNS. Different strategies for efficient CNS delivery have been studied. This article reviews the current approaches to open or facilitate penetration across these barriers for enhanced drug delivery to the CNS. These approaches are summarized into three broad categories: noninvasive, invasive, and miscellaneous techniques. The progresses made using these approaches are reviewed, and the associated mechanisms and problems are discussed. Keywords: drug delivery system, blood–brain barrier (BBB, central nervous system, brain-targeted therapy, cerebrospinal fluid (CSF

  17. Foxp3+ regulatory T cells control persistence of viral CNS infection.

    Directory of Open Access Journals (Sweden)

    Dajana Reuter

    Full Text Available We earlier established a model of a persistent viral CNS infection using two week old immunologically normal (genetically unmodified mice and recombinant measles virus (MV. Using this model infection we investigated the role of regulatory T cells (Tregs as regulators of the immune response in the brain, and assessed whether the persistent CNS infection can be modulated by manipulation of Tregs in the periphery. CD4(+ CD25(+ Foxp3(+ Tregs were expanded or depleted during the persistent phase of the CNS infection, and the consequences for the virus-specific immune response and the extent of persistent infection were analyzed. Virus-specific CD8(+ T cells predominantly recognising the H-2D(b-presented viral hemagglutinin epitope MV-H(22-30 (RIVINREHL were quantified in the brain by pentamer staining. Expansion of Tregs after intraperitoneal (i.p. application of the superagonistic anti-CD28 antibody D665 inducing transient immunosuppression caused increased virus replication and spread in the CNS. In contrast, depletion of Tregs using diphtheria toxin (DT in DEREG (depletion of regulatory T cells-mice induced an increase of virus-specific CD8(+ effector T cells in the brain and caused a reduction of the persistent infection. These data indicate that manipulation of Tregs in the periphery can be utilized to regulate virus persistence in the CNS.

  18. Detail Design of the hydrogen system and the gas blanketing system for the HANARO-CNS

    International Nuclear Information System (INIS)

    Choi, Jung Woon; Kim, Hark Rho; Kim, Young Ki; Wu, Sang Ik; Kim, Bong Su; Lee, Yong Seop

    2007-04-01

    The cold neutron source (CNS), which will be installed in the vertical CN hole of the reflector tank at HANARO, makes thermal neutrons to moderate into the cold neutrons with the ranges of 0.1 ∼ 10 meV passing through a moderator at about 22K. A moderator to produce cold neutrons is liquid hydrogen, which liquefies by the heat transfer with cryogenic helium flowing from the helium refrigeration system (HRS). Because of its installed location, the hydrogen system is designed to be surrounded by the gas blanketing system to notify the leakage on the system and to prevent hydrogen leakage out of the CNS. The hydrogen system, consisted of hydrogen charging unit, hydrogen storage unit, hydrogen buffer tank, and hydrogen piping, is designed to smoothly and safely supply hydrogen to and to draw back hydrogen from the IPA of the CNS under the HRS operation mode. Described is that calculation for total required hydrogen amount in the CNS as well as operation schemes of the hydrogen system. The gas blanketing system (GBS) is designed for the supply of the compressed nitrogen gas into the air pressurized valves for the CNS, to isolate the hydrogen system from the air and the water, and to prevent air or water intrusion into the vacuum system as well as the hydrogen system. All detail descriptions are shown inhere as well as the operation scheme for the GBS

  19. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  20. [11C]NS8880, a promising PET radiotracer targeting the norepinephrine transporter

    DEFF Research Database (Denmark)

    Vase, Karina Højrup; Peters, Dan; Nielsen, Elsebeth Ø

    2014-01-01

    -azabicyclo[3.2.1]octane (NS8880), targeting NET. NS8880 has an in vitro binding profile comparable to desipramine and is structurally not related to reboxetine. METHODS: Labeling of NS8880 with [11C] was achieved by a non-conventional technique: substitution of pyridinyl fluorine with [11C]methanolate...... yields with high purity. The PET in vivo evaluation in pig and rat revealed a rapid brain uptake of [11C]NS8880 and fast obtaining of equilibrium. Highest binding was observed in thalamic and hypothalamic regions. Pretreatment with desipramine efficiently reduced binding of [11C]NS8880. CONCLUSION: Based...... on the pre-clinical results obtained so far [11C]NS8880 displays promising properties for PET imaging of NET....

  1. Serial brain MRI findings in CNS involvement of familial erythrophagocytic lymphohistiocytosis: a case report

    International Nuclear Information System (INIS)

    Cho, Kyung Soo; Yoo, Jeong Hyun; Suh, Jeong Soo; Ryu, Kyung Ha; Hong, Ki Sook; Kim, Hak Jin

    2002-01-01

    Familial erythrophagocytic lymphohistiocytosis is a fatal early childhood disorder characterized by multiorgan lymphohistiocytic infiltration and active hemophagocytosis. Involvement of the central nervous system (CNS) is not uncommon and is characterized by rapidly progressive tissue damage affecting both the gray and white matter. We encountered a case of familial erythrophagocytic lymphohistiocytosis with CNS involvement. Initial T2-weighted MRI of the brain demonstrated high signal intensity in the right thalamus, though after chemotherapy, which led to the relief of neurologic symptoms, this disappeared. After four months. however, the patient's neurologic symptoms recurred, and follow-up T2-weighted MR images showed high signal intensity in the thalami, basal ganglia, and cerebral and cerebellar white matter. Brain MRI is a useful imaging modality for the evaluation of CNS involvement and monitoring the response to treatment

  2. Analysis of neurocognitive function and CNS endpoints in the PROTEA trial

    DEFF Research Database (Denmark)

    Clarke, Amanda; Johanssen, Veronika; Gerstoft, Jan

    2014-01-01

    INTRODUCTION: During treatment with protease inhibitor monotherapy, the number of antiretrovirals with therapeutic concentrations in the cerebrospinal fluid (CSF) is lower, compared to standard triple therapy. However, the clinical consequences are unclear. METHODS: A total of 273 patients with HIV...... and the Grooved Pegboard Test at screening, baseline and at Week 48. A global neurocognitive score (NPZ-5) was derived by averaging the standardized results of the five domains. In a central nervous system (CNS) sub-study (n=70), HIV RNA levels in the CNS were evaluated at baseline and Week 48. Clinical adverse...... events related to the CNS were collected at each visit. RESULTS: Patients were 83% male and 88% White, with median age 43 years. There were more patients with nadir CD4 count below 200 cells/µL in the DRV/r monotherapy arm (41/137, 30%) than the triple therapy arm (30/136, 22%). At Week 48...

  3. Intellectual abilities among survivors of childhood leukaemia as a function of CNS irradiation

    International Nuclear Information System (INIS)

    Eiser, C.

    1978-01-01

    Twenty-eight children in remission at least 2 years after completing chemotherapy for acute lymphoblastic leukaemia were assessed on standardised psychological tests. It was found that 7 who never had central nervous system (CNS) irradiation and 9 having prophylactic CNS irradiation at least 6 months after diagnosis tended to perform at average or above levels, while those 10 each having prophylactic CNS irradiation (within 2 months of diagnosis) were generally at lower ability. Within the latter group 3 children showed serious intellectual impairments, while the group as a whole functioned especially poorly on quantitative tasks and those involving speeded performance with abstract material. General language ability was not affected. Practical and theoretical implications are discussed. (author)

  4. Cancers of the Brain and CNS: Global Patterns and Trends in Incidence.

    Science.gov (United States)

    Mortazavi, S M J; Mortazavi, S A R; Paknahad, M

    2018-03-01

    Miranda-Filho et al. in their recently published paper entitled "Cancers of the brain and CNS: global patterns and trends in incidence" provided a global status report of the geographic and temporal variations in the incidence of brain and CNS cancers in different countries across continents worldwide. While the authors confirm the role of genetic risk factors and ionizing radiation exposures, they claimed that no firm conclusion could be drawn about the role of exposure to non-ionizing radiation. The paper authored by Miranda-Filho et al. not only addresses a challenging issue, it can be considered as a good contribution in the field of brain and CNS cancers. However, our correspondence addresses a basic shortcoming of this paper about the role of electromagnetic fields and cancers and provides evidence showing that exposure to radiofrequency electromagnetic fields (RF-EMFs), at least at high levels and long durations, can increases the risk of cancer.

  5. Neonatal CNS infection and inflammation caused by Ureaplasma species: rare or relevant?

    Science.gov (United States)

    Glaser, Kirsten; Speer, Christian P

    2015-02-01

    Colonization with Ureaplasma species has been associated with adverse pregnancy outcome, and perinatal transmission has been implicated in the development of bronchopulmonary dysplasia in preterm neonates. Little is known about Ureaplasma-mediated infection and inflammation of the CNS in neonates. Controversy remains concerning its incidence and implication in the pathogenesis of neonatal brain injury. In vivo and in vitro data are limited. Despite improving care options for extremely immature preterm infants, relevant complications remain. Systematic knowledge of ureaplasmal infection may be of great benefit. This review aims to summarize pathogenic mechanisms, clinical data and diagnostic pitfalls. Studies in preterm and term neonates are critically discussed with regard to their limitations. Clinical questions concerning therapy or prophylaxis are posed. We conclude that ureaplasmas may be true pathogens, especially in preterm neonates, and may cause CNS inflammation in a complex interplay of host susceptibility, serovar pathogenicity and gestational age-dependent CNS vulnerability.

  6. GEOMETRY OF WAVES GUIDES FOR CONTAINMENT OF ...

    African Journals Online (AJOL)

    30 juin 2011 ... ABSTRACT. We are study de mode fundamental de 1D in the two media (MIM and IMI) of a metallic structure (Ag) (silver) in which a small hole is perforated (as à dielectric medium). We take the conditions that resonant modes (PPSs) are confined or the surface.Via the complex permittivity of the metal and ...

  7. Guided Terahertz Waves for Characterizing Explosives

    Science.gov (United States)

    2009-01-01

    Spectroscopy of Nanometer Water Layers,” Optics Letters 29, 1617–1619 (2004). 4 J. S. Melinger, N. Laman , S. Sree Harsha, and D. Grischkowsky, “Line...2006). 5 N. Laman , S. Sree Harsha, D. Grischkowsky, and J.S. Melinger, “7 GHz Resolution Waveguide THz Spectroscopy of Explosives Related Solids...Showing New Features,” Optics Express 16, 4094–4105 (2008). 6 J.S. Melinger, N. Laman , and D. Grischkowsky, “The Underlying Terahertz Vibrational

  8. Guided wave sensing of polyelectrolyte multilayers

    DEFF Research Database (Denmark)

    Horvath, R.; Pedersen, H.C.; Cuisinier, F.J.G.

    2006-01-01

    A planar optical waveguide configuration is proposed to monitor the buildup of thick polyelectrolyte multilayers on the surface of the waveguide in aqueous solutions. Instead of detecting the layer by the electromagnetic evanescent field the polyelectrolyte layer acts as an additional waveguiding...

  9. Shock wave loading of a magnetic guide

    NARCIS (Netherlands)

    Kindt, L.

    2011-01-01

    The atom laser has long been a holy grail within atom physics and with the creation of an atom laser we hope to bring a similar revolution in to the field of atom optics. With the creation of the Bose-Einstein Condensate (BEC) in 1995 the path to an atom laser was initiated. An atom laser is

  10. Clearance of an immunosuppressive virus from the CNS coincides with immune reanimation and diversification

    Directory of Open Access Journals (Sweden)

    McGavern Dorian B

    2007-06-01

    Full Text Available Abstract Once a virus infection establishes persistence in the central nervous system (CNS, it is especially difficult to eliminate from this specialized compartment. Therefore, it is of the utmost importance to fully understand scenarios during which a persisting virus is ultimately purged from the CNS by the adaptive immune system. Such a scenario can be found following infection of adult mice with an immunosuppressive variant of lymphocytic choriomeningitis virus (LCMV referred to as clone 13. In this study we demonstrate that following intravenous inoculation, clone 13 rapidly infected peripheral tissues within one week, but more slowly inundated the entire brain parenchyma over the course of a month. During the establishment of persistence, we observed that genetically tagged LCMV-specific cytotoxic T lymphocytes (CTL progressively lost function; however, the severity of this loss in the CNS was never as substantial as that observed in the periphery. One of the most impressive features of this model system is that the peripheral T cell response eventually regains functionality at ~60–80 days post-infection, and this was associated with a rapid decline in virus from the periphery. Coincident with this "reanimation phase" was a massive influx of CD4 T and B cells into the CNS and a dramatic reduction in viral distribution. In fact, olfactory bulb neurons served as the last refuge for the persisting virus, which was ultimately purged from the CNS within 200 days post-infection. These data indicate that a functionally revived immune response can prevail over a virus that establishes widespread presence both in the periphery and brain parenchyma, and that therapeutic enhancement of an existing response could serve as an effective means to thwart long term CNS persistence.

  11. CD11c-expressing cells affect Treg behavior in the meninges during CNS infection1

    Science.gov (United States)

    O’Brien, Carleigh A.; Overall, Christopher; Konradt, Christoph; O’Hara Hall, Aisling C.; Hayes, Nikolas W.; Wagage, Sagie; John, Beena; Christian, David A.; Hunter, Christopher A.; Harris, Tajie H.

    2017-01-01

    Treg cells play an important role in the CNS during multiple infections as well as autoimmune inflammation, but the behavior of this cell type in the CNS has not been explored. In mice, infection with Toxoplasma gondii leads to a Th1-polarized parasite-specific effector T cell response in the brain. Similarly, the Treg cells in the CNS during T. gondii infection are Th1-polarized, exemplified by T-bet, CXCR3, and IFN-γ expression. Unlike effector CD4+ T cells, an MHC Class II tetramer reagent specific for T. gondii did not recognize Treg cells isolated from the CNS. Likewise, TCR sequencing revealed minimal overlap in TCR sequence between effector and regulatory T cells in the CNS. Whereas effector T cells are found in the brain parenchyma where parasites are present, Treg cells were restricted to the meninges and perivascular spaces. The use of intravital imaging revealed that activated CD4+ T cells within the meninges were highly migratory, while Treg cells moved more slowly and were found in close association with CD11c+ cells. To test whether the behavior of Tregs in the meninges is influenced by interactions with CD11c+ cells, mice were treated with anti-LFA-1 antibodies to reduce the number of CD11c+ cells in this space. The anti-LFA-1 treatment led to fewer contacts between Tregs and the remaining CD11c+ cells and increased the speed of Treg cell migration. These data suggest that Treg cells are anatomically restricted within the CNS and the interaction with CD11c+ populations regulates their local behavior during T. gondii infection. PMID:28389591

  12. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and spasms due ... that the body is having trouble with the heat. If a heat wave is predicted or happening… - ...

  13. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  14. Kinetic modelling of [123I]CNS 1261--a potential SPET tracer for the NMDA receptor

    International Nuclear Information System (INIS)

    Erlandsson, Kjell; Bressan, Rodrigo A.; Mulligan, Rachel S.; Gunn, Roger N; Cunningham, Vincent J.; Owens, Jonathan; Wyper, David; Ell, Peter J.; Pilowsky, Lyn S.

    2003-01-01

    N-(1-napthyl)-N'-(3-[ 123 I]-iodophenyl)-N-methylguanidine ([ 123 I]CNS 1261) is a novel SPET ligand developed for imaging the NMDA receptor intra-channel MK 801/PCP/ketamine site. Data was acquired in 7 healthy volunteers after bolus injection of [ 123 I]CNS 1261. Kinetic modeling showed reversible tracer binding. Arterial and venous time-activity curves overlapped after 90 min. The rank order of binding was: Thalamus > striatum > cortical regions > white matter. This distribution concurs with [ 11 C]-ketamine and [ 18 F]-memantine PET studies . These data provide a methodological basis for further direct in vivo challenge studies

  15. Effects of x rays on the morphology and physiology of the CNS blood vessels of mice

    Energy Technology Data Exchange (ETDEWEB)

    Gladysz, J [Akademia Medyczna, Poznan (Poland)

    1974-01-01

    Irradiation of the CNS of mice with 4000 to 7600 R produces transitional disorder of the permeability of vascular walls, followed by a permanent (irreversible) degenerative lesion of blood capillaries and the surrounding astrogial cells. Intensity of this alterations may however not be the same in different terminal blood vessels. It is very likely that the above described lesion appearing in the acute phase can be the main cause of further alterations in the CNS which are observed in late phase of postradiation disease.

  16. Lentiviral-mediated administration of IL-25 in the CNS induces alternative activation of microglia

    DEFF Research Database (Denmark)

    Maiorino, C; Khorooshi, R; Ruffini, F

    2013-01-01

    Interleukin-25 (IL-25) is the only anti-inflammatory cytokine of the IL-17 family, and it has been shown to be efficacious in inhibiting neuroinflammation. Known for its effects on cells of the adaptive immune system, it has been more recently described to be effective also on cells of the innate...... was partly inhibited and the CNS protected from immune-mediated damage. To our knowledge, this is the first example of M2 shift (alternative activation) induced in vivo on CNS-resident myeloid cells by gene therapy, and may constitute a promising strategy to investigate the potential role of protective...

  17. Metallothionein-1+2 protect the CNS after a focal brain injury

    DEFF Research Database (Denmark)

    Giralt, Mercedes; Penkowa, Milena; Lago, Natalia

    2002-01-01

    We have evaluated the physiological relevance of metallothionein-1+2 (MT-1+2) in the CNS following damage caused by a focal cryolesion onto the cortex. In comparison to normal mice, transgenic mice overexpressing the MT-1 isoform (TgMTI* mice) showed a significant decrease of the number...... dramatically reduced the cryolesion-induced oxidative stress and neuronal apoptosis. Remarkably, these effects were also obtained by the intraperitoneal administration of MT-2 to both normal and MT-1+2 knock-out mice. These results fully support the notion that MT-1+2 are essential in the CNS for coping...

  18. Imaging aspects of neurologic emergencies in children treated for non-CNS malignancies

    International Nuclear Information System (INIS)

    Kaste, S.C.; Langston, J.; Rodriguez-Galindo, C.; Furman, W.L.; Thompson, S.J.

    2000-01-01

    There is a paucity of radiologic literature addressing neurologic emergencies in children receiving therapy for non-CNS primary malignancies. In the acute setting, many of these children present to local community hospitals. This pictorial is from a single institutional experience describing the spectrum of neurologic emergencies seen in children with non-CNS cancers. We hope to familiarize pediatric radiologists with these entities in order to expedite diagnosis, facilitate treatment, and minimize morbity and mortality that may be associated with these complications. (orig.)

  19. Neuroprotective effects of estrogen in CNS injuries: insights from animal models

    Directory of Open Access Journals (Sweden)

    Raghava N

    2017-07-01

    Full Text Available Narayan Raghava,1 Bhaskar C Das,2 Swapan K Ray1 1Department of Pathology, Microbiology, and Immunology, University of South Carolina School of Medicine, Columbia, SC, USA; 2Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA Abstract: Among the estrogens that are biosynthesized in the human body, 17β-estradiol (estradiol or E2 is the most common and the best estrogen for neuroprotection in animal models of the central nervous system (CNS injuries such as spinal cord injury (SCI, traumatic brain injury (TBI, and ischemic brain injury (IBI. These CNS injuries are not only serious health problems, but also enormous economic burden on the patients, their families, and the society at large. Studies from animal models of these CNS injuries provide insights into the multiple neuroprotective mechanisms of E2 and also suggest the possibility of translating the therapeutic efficacy of E2 in the treatment SCI, TBI, and IBI in humans in the near future. The pathophysiology of these injuries includes loss of motor function in the limbs, arms and their extremities, cognitive deficit, and many other serious consequences including life-threatening paralysis, infection, and even death. The potential application of E2 therapy to treat the CNS injuries may become a trend as the results are showing significant therapeutic benefits of E2 for neuroprotection when administered into the animal models of SCI, TBI, and IBI. This article describes the plausible mechanisms how E2 works with or without the involvement of estrogen receptors and provides an overview of the known neuroprotective effects of E2 in these three CNS injuries in different animal models. Because activation of estrogen receptors has profound implications in maintaining and also affecting normal physiology, there are notable impediments in translating E2 therapy to the clinics for neuroprotection in CNS injuries in humans. While E2 may not yet be the sole molecule for

  20. Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Jonah Maxwell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-18

    This report has slides on Gravitational Waves; Pound and Rebka: A Shocking Fact; Light is a Ruler; Gravity is the Curvature of Spacetime; Gravitational Waves Made Simple; How a Gravitational Wave Affects Stuff Here; LIGO; This Detection: Neutron Stars; What the Gravitational Wave Looks Like; The Sound of Merging Neutron Stars; Neutron Star Mergers: More than GWs; The Radioactive Cloud; The Kilonova; and finally Summary, Multimessenger Astronomy.