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Sample records for fiber conduction velocity

  1. Muscle Fiber Conduction Velocity, Muscle Fiber Composition, and Power Performance.

    Science.gov (United States)

    Methenitis, Spyridon; Karandreas, Nikolaos; Spengos, Konstantinos; Zaras, Nikolaos; Stasinaki, Angeliki-Nikoletta; Terzis, Gerasimos

    2016-09-01

    The aim of this study was to explore the relationship between muscle fiber conduction velocity (MFCV), fiber type composition, and power performance in participants with different training background. Thirty-eight young males with different training background participated: sedentary (n = 10), endurance runners (n = 9), power trained (n = 10), and strength trained (n = 9). They performed maximal countermovement jumps (CMJ) and maximal isometric leg press for the measurement of the rate of force development (RFD). Resting vastus lateralis MFCV was measured with intramuscular microelectrodes on a different occasion, whereas muscle fiber type and cross-sectional area (CSA) of vastus lateralis were evaluated through muscle biopsies 1wk later. MFCV, CMJ power, RFD, and % CSA of type II and type IIx fibers were higher for the power-trained group (P power participants. Close correlations were found between MFCV and fiber CSA as well as the % CSA of all fiber types as well as with RFD and CMJ power (r = 0.712-0.943, P power performance. Significant models for the prediction of the % CSA of type IIa and type II as well as the CSA of all muscle fibers based upon MFCV, RFD, and CMJ were revealed (P = 0.000). MFCV is closely associated with muscle fiber % CSA. RFD and jumping power are associated with the propagation of the action potentials along the muscle fibers. This link is regulated by the size and the distribution of type II, and especially type IIx muscle fibers.

  2. Intramuscular fiber conduction velocity, isometric force and explosive performance

    OpenAIRE

    Methenitis Spyridon; Terzis Gerasimos; Zaras Nikolaos; Stasinaki Angeliki-Nikoletta; Karandreas Nikolaos

    2016-01-01

    Conduction of electrical signals along the surface of muscle fibers is acknowledged as an essential neuromuscular component which is linked with muscle force production. However, it remains unclear whether muscle fiber conduction velocity (MFCV) is also linked with explosive performance. The aim of the present study was to investigate the relationship between vastus lateralis MFCV and countermovement jumping performance, the rate of force development and maximum isometric force. Fifteen moder...

  3. Intramuscular fiber conduction velocity, isometric force and explosive performance

    OpenAIRE

    Methenitis, Spyridon; Terzis, Gerasimos; Zaras, Nikolaos; Stasinaki, Angeliki-Nikoletta; Karandreas, Nikolaos

    2016-01-01

    Abstract Conduction of electrical signals along the surface of muscle fibers is acknowledged as an essential neuromuscular component which is linked with muscle force production. However, it remains unclear whether muscle fiber conduction velocity (MFCV) is also linked with explosive performance. The aim of the present study was to investigate the relationship between vastus lateralis MFCV and countermovement jumping performance, the rate of force development and maximum isometric force. Fift...

  4. Intramuscular fiber conduction velocity, isometric force and explosive performance.

    Science.gov (United States)

    Methenitis, Spyridon; Terzis, Gerasimos; Zaras, Nikolaos; Stasinaki, Angeliki-Nikoletta; Karandreas, Nikolaos

    2016-06-01

    Conduction of electrical signals along the surface of muscle fibers is acknowledged as an essential neuromuscular component which is linked with muscle force production. However, it remains unclear whether muscle fiber conduction velocity (MFCV) is also linked with explosive performance. The aim of the present study was to investigate the relationship between vastus lateralis MFCV and countermovement jumping performance, the rate of force development and maximum isometric force. Fifteen moderately-trained young females performed countermovement jumps as well as an isometric leg press test in order to determine the rate of force development and maximum isometric force. Vastus lateralis MFCV was measured with intramuscular microelectrodes at rest on a different occasion. Maximum MFCV was significantly correlated with maximum isometric force (r = 0.66, p rate of force development at 100 ms, 150 ms, 200 ms, and 250 ms (r = 0.85, r = 0.89, r = 0.91, r = 0.92, respectively, p rate of force development than with maximum isometric leg press force. Lower, but significant correlations were found between mean MFCV and countermovement jump power (r = 0.65, p rate of force development than with isometric force, perhaps because conduction velocity is higher in the larger and fastest muscle fibers which are recognized to contribute to explosive actions.

  5. A new surface electromyography analysis method to determine spread of muscle fiber conduction velocities

    NARCIS (Netherlands)

    Lange, F; Van Weerden, TW; Van der Hoeven, JH

    2002-01-01

    Muscle fiber conduction velocity (MFCV) estimation from surface signals is widely used to study muscle function, e. g., in neuromuscular disease and in fatigue studies. However, most analysis methods do not yield information about the velocity distribution of the various motor unit action potentials

  6. Diagnostic value of the muscle fiber conduction velocity for evaluation of muscle hypotrophy.

    Science.gov (United States)

    Gechev, Antonin G; Ilieva, Elena M; Marinkev, Marin D; Hadjigeorgiev, Georgi H

    2004-01-01

    To find an objective method of evaluation of the thigh muscle hypothrophy in gonarthrosis. The subjects of the study were 24 patients with gonarthrosis (mean age 58.4 +/- 2.6 years). Of these 8 (33%) were males and 16 (67%) females. The following methods of examination were used: computed tomography (CT) of the thigh musculature--linear measurement and area of the cross-section of the vastus medialis muscle; electromyography--muscle fiber conduction velocity; and measurement of thigh girth. Significant reduction of the cross-section area and linear measurement of the vastus medialis muscle and significant delay of the muscle fiber conduction velocity was found in the symptomatic side compared with the asymptomatic side. No correlation was found between the tape measure of the thigh and cross-section area of the muscle. A significant correlation was found between the cross-section area of the muscle and the fast fiber conduction velocity as well as between the linear measurement of the vastus medialis muscle cross-section and fast fiber conduction velocity. The correlation between the macromorphological changes of the vastus medialis muscle assessed by computed tomography and the functional changes detected by electromyography allows the conclusion that the muscle fiber conduction velocity can be used as an objective method of evaluation of muscle atrophy in degenerative joint diseases.

  7. Age-related botulinum toxin effects on muscle fiber conduction velocity in non-injected muscles

    NARCIS (Netherlands)

    Lange, Fiete; van Weerden, Tiemen W.; van der Hoeven, Johannes H.

    2007-01-01

    Objective: We studied systemic effects of botulinum toxin (BTX) treatment on muscle fiber conduction velocity (MFCV) and possible effects of age. Methods: MFCV was determined by an invasive EMG method in the biceps brachii muscle. Seventeen BTX treated patients and 58 controls were investigated. BTX

  8. SUPERNORMAL MUSCLE-FIBER CONDUCTION-VELOCITY DURING INTERMITTENT ISOMETRIC-EXERCISE IN HUMAN MUSCLE

    NARCIS (Netherlands)

    VANDERHOEVEN, JH; LANGE, F

    1994-01-01

    Muscle fiber conduction velocity (MFCV) and surface electromyographic parameters were studied in the brachial biceps muscle of healthy males during voluntary intermittent isometric contractions at 50% of maximum force. Recovery in the following 15 min was then observed. The measurements were perform

  9. Effects of muscle fiber type and size on EMG median frequency and conduction velocity.

    Science.gov (United States)

    Kupa, E J; Roy, S H; Kandarian, S C; De Luca, C J

    1995-07-01

    This paper describes an in vitro method for comparing surface-detected electromyographic median frequency (MF) and conduction velocity (CV) parameters with histochemical measurements of muscle fiber type composition and cross-sectional area (CSA). Electromyographic signals were recorded during electrically elicited tetanic contractions from rat soleus, extensor digitorum longus, and diaphragm muscles placed in an oxygenated Krebs bath. Fibers were typed as slow oxidative, fast oxidative glycolytic, and fast glycolytic based on histochemical enzyme stains. Muscles with a greater percentage of fast glycolytic and fast oxidative glycolytic fibers exhibited greater initial values of MF and CV as well as a greater reduction in these variables over the course of the contraction. Regression indicated that fiber type composition could be predicted based on two MF parameters. A weighted measure of muscle fiber CSA was found to be linearly related to both initial MF and CV. The results of this study suggest that MF and CV parameters recorded during a muscular contraction are related to muscle fiber type composition and muscle fiber CSA.

  10. Decrease of muscle fiber conduction velocity correlates with strength loss after an endurance run.

    Science.gov (United States)

    Boccia, Gennaro; Dardanello, Davide; Tarperi, Cantor; Rosso, Valeria; Festa, Luca; La Torre, Antonio; Pellegrini, Barbara; Schena, Federico; Rainoldi, Alberto

    2017-02-01

    Monitoring surface electromyographic (EMG) signals can provide useful insights for characterizing muscle fatigue, which is defined as an exercise-induced strength loss. This experiment investigated the muscle fiber conduction velocity (CV) changes induced by an endurance run. The day before and immediately after a half-marathon run (21.097 km) 11 amateur runners performed maximum voluntary contractions (MVCs) of knee extensor muscles. During the MVC, multichannel EMG was recorded from the vastus lateralis and EMG amplitude and CV were calculated. After the run, knee extensors showed a decreased strength (-13  ±  9%, p  =  0.001) together with a reduction in EMG amplitude (-13  ±  10%, p  =  0.003) and in CV (-6  ±  8%, p  =  0.032). Knee extensor strength loss positively correlated with vastus lateralis CV differences (r  =  0.76, p  =  0.006). Thus, the exercises-induced muscle fatigue was associated not only with a decrease in EMG amplitude, but also with a reduction in CV. This finding suggests that muscle fibers with higher CV (i.e. those with greater fiber size) were the most impaired during strength production after an endurance run.

  11. Relation between muscle fiber conduction velocity and exerted dynamic characteristics of muscular tension in patients with hemiplegia caused by stroke.

    Science.gov (United States)

    Murakami, Kenichi; Fujisawa, Hiroyuki; Suzuki, Makoto; Sato, Yoichiro; Sakurai, Kentaro; Abe, Chie

    2016-10-01

    [Purpose] The aim of this study was to clarify the relationships among muscle fiber conduction velocity, time-force characteristics of muscle force production, and voluntary movement in patients with hemiplegia. [Subjects and Methods] The participants in the present study were 13 patients with hemiplegia. Muscle fiber conduction velocity, deep temperature of muscles and muscle thickness were measured for the tibialis anterior, and a time force curve was obtained from dorsiflexion of the ankle and lower thigh girth (maximum, minimum) for both sides. The maximum torque rate of change and maximum torque were calculated from the force-time curve. In addition, Brunnstrom Recovery Stage was used to evaluate the function of the hemiplegic side. [Results] In all the measurement items, significant differences were observed between the hemiplegic side and the healthy side. The maximum torque rate of change and Brunnstrom Recovery Stage showed a high degree of correlation. The muscle fiber conduction velocity and maximum torque rate of change or maximum torque showed a medium degree of correlation. However, muscle fiber conduction velocity was not significantly correlated with Brunnstrom Recovery Stage. [Conclusion] Brunnstrom Recovery Stage was good as a determination factor for the maximum torque rate of change. In addition, in patients with hemiplegia, it became clear that relationship is between muscle fiber conduction velocity and time-force characteristics of muscle force production as in healthy persons.

  12. Severe COPD Alters Muscle Fiber Conduction Velocity During Knee Extensors Fatiguing Contraction.

    Science.gov (United States)

    Boccia, Gennaro; Coratella, Giuseppe; Dardanello, Davide; Rinaldo, Nicoletta; Lanza, Massimo; Schena, Federico; Rainoldi, Alberto

    2016-10-01

    The aim of this study was to assess the changes in muscle fiber conduction velocity (CV), as a sign of fatigue during knee extensor contraction in patients with chronic obstructive pulmonary disease (COPD) as compared with healthy controls. Eleven male patients (5 with severe and 6 with moderate COPD; age 67 ± 5 years) and 11 age-matched healthy male controls (age 65 ± 4 years) volunteered for the study. CV was obtained by multichannel surface electromyography (EMG) from the vastus lateralis (VL) and medialis (VM) of the quadriceps muscle during isometric, 30-second duration knee extension at 70% of maximal voluntary contraction. The decline in CV in both the VL and VM was steeper in the severe COPD patients than in healthy controls (for VL: severe COPD vs. controls -0.45 ± 0.07%/s; p < 0.001, and for VM: severe COPD vs. controls -0.54 ± 0.09%/s, p < 0.001). No difference in CV decline was found between the moderate COPD patients and the healthy controls. These findings suggest that severe COPD may impair muscle functions, leading to greater muscular fatigue, as expressed by CV changes. The results may be due to a greater involvement of anaerobic metabolism and a shift towards fatigable type II fibers in the muscle composition of the severe COPD patients.

  13. Muscle fiber conduction velocity in different gait phases of early and late-stage diabetic neuropathy.

    Science.gov (United States)

    Suda, Eneida Yuri; Gomes, Aline A; Butugan, Marco Kenji; Sacco, Isabel C N

    2016-10-01

    We investigated the muscle fiber conduction velocity (MFCV) during gait phases of the lower limb muscles in individuals with various degrees of diabetic peripheral neuropathy (DPN). Forty-five patients were classified into severity degrees of DPN by a fuzzy model. The stages were absent (n=11), mild (n=14), moderate (n=11) and severe (n=9), with 10 matched healthy controls. While walking, all subjects had their sEMG (4 linear electrode arrays) recorded for tibialis anterior (TA), gastrocnemius medialis (GM), vastus lateralis (VL) and biceps femoris (BF). MFCV was calculated using a maximum likelihood algorithm with 30ms standard deviation Gaussian windows. In general, individuals in the earlier stages of DPN showed lower MFCV of TA, GM and BF, whilst individuals with severe DPN presented higher MFCV of the same muscles. We observed that mild patients already showed lower MFCV of TA at early stance and swing, and lower MFCV of BF at swing. All diabetic groups showed a markedly reduction in MFCV of VL, irrespective of DPN. Severe patients presented higher MFCV mainly in distal muscles, TA at early and swing phases and GM at propulsion and midstance. The absent group already showed MFCV of VL and GM reductions at the propulsion phase and of VL at early stance. Although MFCV changes were not as progressive as the DPN was, we clearly distinguished diabetic patients from controls, and severe patients from all others.

  14. Towards Real-Time Estimation of Muscle-Fiber Conduction Velocity using Delay-Locked Loop.

    Science.gov (United States)

    Xu, Lin; Rabotti, Chiara; Mischi, Massimo

    2016-11-24

    Decrease in muscle-fiber conduction velocity (MFCV) during sustained contraction has been widely accepted as myoelectric manifestation of muscle fatigue. Several methods have been proposed in the literature for MFCV estimation by analysing surface electromyography (EMG), e.g., cross-correlation (CC) function and maximum likelihood (ML). However, for all the available methods, windowing of the EMG signal and computationally demanding calculations are required, limiting the possibility to continuously monitor muscle fatigue in real time. In the present study, an adaptive scheme is proposed that permits real-time estimation of MFCV. The proposed scheme is based on a delay-locked loop (DLL). A second-order loop is adopted to track the delay variation over time. An error filter is employed to approximate a ML estimation in case of colored noise. Furthermore, the DLL system is extended for multichannel CV estimation. The performance of the proposed method is evaluated by both dedicated simulations and real EMG signals. Our results show the accuracy of the proposed method to be comparable to that of the ML method for much lower (1/40) computational complexity, especially suited for real-time MFCV measurements. Use of this method can enable new studies on myoelectric fatigue, possibly leading to new insight on the underlying physiological processes.

  15. MUSCLE-FIBER CONDUCTION-VELOCITY IN THE DIAGNOSIS OF FAMILIAL HYPOKALEMIC PERIODIC PARALYSIS - INVASIVE VERSUS SURFACE DETERMINATION

    NARCIS (Netherlands)

    VANDERHOEVEN, JH; LINKS, TP; ZWARTS, MJ; VANWEERDEN, TW

    1994-01-01

    Muscle fiber conduction velocity (MFCV) in the brachial biceps muscle was determined in a large family of patients with hypokalemic periodic paralysis (HOPP) by both a surface and an invasive method. Other surface EMG parameters and the muscle force were also determined. Both the surface and the inv

  16. Changes in human muscle oxygen saturation and mean fiber conduction velocity during intense dynamic exercise - effect of muscular training status

    DEFF Research Database (Denmark)

    Kilen, Anders; Gizzi, Leonardo; Jensen, Bente Rona

    2012-01-01

    Introduction: In this study we investigated whether an association exists between muscle fiber conduction velocity (MFCV) and local muscle oxygen saturation (StO(2) ) in the superficial part of the latissimus dorsi muscle of runners and swimmers during exhaustive dynamic exercise. Methods: Partic...

  17. Analysis of muscle fiber conduction velocity enables reliable detection of surface EMG crosstalk during detection of nociceptive withdrawal reflexes.

    Science.gov (United States)

    Jensen, Michael Brun; Manresa, José Alberto Biurrun; Frahm, Ken Steffen; Andersen, Ole Kæseler

    2013-03-26

    The nociceptive withdrawal reflex (NWR) is a polysynaptic spinal reflex that induces complex muscle synergies to withdraw a limb from a potential noxious stimulus. Several studies indicate that assessment of the NWR is a valuable objective tool in relation to investigation of various pain conditions. However, existing methodologies for NWR assessment evaluate standard surface electromyography (sEMG) measured over just one muscle and do not consider the possible interference of crosstalk originating from adjacent active muscles. The present study had two aims: firstly, to investigate to which extent the presence of crosstalk may affect NWR detection using a standardized scoring criterion (interval peak z-score) that has been validated without taking crosstalk into consideration. Secondly, to investigate whether estimation of muscle fiber conduction velocity can help identifying the propagating and non-propagating nature of genuine reflexes and crosstalk respectively, thus allowing a more valid assessment of the NWR. Evaluation of interval peak z-score did apparently allow reflex detection with high sensitivity and specificity (0.96), but only if the influence of crosstalk was ignored. Distinction between genuine reflexes and crosstalk revealed that evaluation of interval peak z-score incorporating a z-score threshold of 12 was associated with poor reflex detection specificity (0.26-0.62) due to the presence of crosstalk. Two different standardized methods for estimation of muscle fiber conduction velocity were employed to demonstrate that significantly different muscle fiber conduction velocities may be estimated during genuine reflexes and crosstalk, respectively. This discriminative feature was used to develop and evaluate a novel methodology for reflex detection from sEMG that is robust with respect to crosstalk. Application of this conduction velocity analysis (CVA) entailed reflex detection with excellent sensitivity (1.00 and 1.00) and specificity (1.00 and 0

  18. Muscle fiber conduction velocity and fractal dimension of EMG during fatiguing contraction of young and elderly active men.

    Science.gov (United States)

    Boccia, Gennaro; Dardanello, Davide; Beretta-Piccoli, Matteo; Cescon, Corrado; Coratella, Giuseppe; Rinaldo, Nicoletta; Barbero, Marco; Lanza, Massimo; Schena, Federico; Rainoldi, Alberto

    2016-01-01

    Over the past decade, linear and nonlinear surface electromyography (EMG) variables highlighting different components of fatigue have been developed. In this study, we tested fractal dimension (FD) and conduction velocity (CV) rate of changes as descriptors, respectively, of motor unit synchronization and peripheral manifestations of fatigue. Sixteen elderly (69  ±  4 years) and seventeen young (23  ±  2 years) physically active men (almost 3-5 h of physical activity per week) executed one knee extensor contraction at 70% of a maximal voluntary contraction for 30 s. Muscle fiber CV and FD were calculated from the multichannel surface EMG signal recorded from the vastus lateralis and medialis muscles. The main findings were that the two groups showed a similar rate of change of CV, whereas FD rate of change was higher in the young than in the elderly group. The trends were the same for both muscles. CV findings highlighted a non-different extent of peripheral manifestations of fatigue between groups. Nevertheless, FD rate of change was found to be steeper in the elderly than in the young, suggesting a greater increase in motor unit synchronization with ageing. These findings suggest that FD analysis could be used as a complementary variable providing further information on central mechanisms with respect to CV in fatiguing contractions.

  19. Conduction velocity of antigravity muscle action potentials.

    Science.gov (United States)

    Christova, L; Kosarov, D; Christova, P

    1992-01-01

    The conduction velocity of the impulses along the muscle fibers is one of the parameters of the extraterritorial potentials of the motor units allowing for the evaluation of the functional state of the muscles. There are no data about the conduction velocities of antigravity muscleaction potentials. In this paper we offer a method for measuring conduction velocity of potentials of single MUs and the averaged potentials of the interference electromiogram (IEMG) lead-off by surface electrodes from mm. sternocleidomastoideus, trapezius, deltoideus (caput laterale) and vastus medialis. The measured mean values of the conduction velocity of antigravity muscles potentials can be used for testing the functional state of the muscles.

  20. Nerve conduction velocity

    Science.gov (United States)

    ... to measure the speed of the nerve signals. Electromyography (recording from needles placed into the muscles) is ... Often, the nerve conduction test is followed by electromyography (EMG). In this test, needles are placed into ...

  1. High Threshold, Proximal Initiation, and Slow Conduction Velocity of Action Potentials in Dentate Granule Neuron Mossy Fibers

    OpenAIRE

    Kress, Geraldine J.; Dowling, Margaret J.; Meeks, Julian P.; Mennerick, Steven

    2008-01-01

    Dentate granule neurons give rise to some of the smallest unmyelinated fibers in the mammalian CNS, the hippocampal mossy fibers. These neurons are also key regulators of physiological and pathophysiological information flow through the hippocampus. We took a comparative approach to studying mossy fiber action potential initiation and propagation in hippocampal slices from juvenile rats. Dentate granule neurons exhibited axonal action potential initiation significantly more proximal than CA3 ...

  2. Single-mode fiber, velocity interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Krauter, K. G.; Jacobson, G. F.; Patterson, J. R.; Nguyen, J. H.; Ambrose, W. P. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore California 94551 (United States)

    2011-04-15

    In this paper, we describe a velocity interferometer system based entirely on single-mode fiber optics. This paper includes a description of principles used in developing the single-mode velocity interferometry system (SMV). The SMV design is based on polarization-insensitive components. Polarization adjusters are included to eliminate the effects of residual birefringence and polarization dependent losses in the interferometers. Characterization measurements and calibration methods needed for data analysis and a method of data analysis are described. Calibration is performed directly using tunable lasers. During development, we demonstrated its operation using exploding-foil bridge-wire fliers up to 200 m/s. In a final test, we demonstrated the SMV in a gas gun experiment up to 1.2 km/sec. As a basis for comparison in the gas gun experiment, we used another velocimetry technique that is also based on single-mode fiber optics: photonic Doppler velocimetry (PDV). For the gas gun experiment, we split the light returned from a single target spot and performed a direct comparison of the homodyne (SMV) and heterodyne (PDV) techniques concurrently. The two techniques had a negligible mean difference and a 1.5% standard deviation in the one-dimensional shock zone. Within one interferometer delay time after a sudden Doppler shift, a SMV unencumbered by multimode-fiber dispersion exhibits two color beats. These beats have the same period as PDV beats--this interference occurs between the ''recently'' shifted and ''formerly unshifted'' paths within the interferometer. We believe that recognizing this identity between homodyne and heterodyne beats is novel in the shock-physics field. SMV includes the conveniences of optical fiber, while removing the time resolution limitations associated with the multimode delivery fiber.

  3. Decreased Nerve Conduction Velocity in Football Players

    Directory of Open Access Journals (Sweden)

    Daryoush Didehdar

    2014-06-01

    Full Text Available Background: Lower limbs nerves are exposed to mechanical injuries in the football players and the purpose of this study is to evaluate the influence of football on the lower leg nerves. Materials and Methods: Nerve conduction studies were done on 35 male college students (20 football players, 15 non active during 2006 to 2007 in the Shiraz rehabilitation faculty. Standard nerve conduction techniques using to evaluate dominant and non dominant lower limb nerves. Results: The motor latency of deep peroneal and tibial nerves of dominant leg of football players and sensory latency of superficial peroneal, tibial and compound nerve action potential of tibial nerve of both leg in football players were significantly prolonged (p<0.05. Motor and sensory nerve conduction velocity of tibial and common peroneal in football players were significant delayed (p<0.05. Conclusion: It is concluded that football is sport with high contact and it causes sub-clinical neuropathies due to nerve entrapment.

  4. Selective measurement of digital nerve conduction velocity.

    Science.gov (United States)

    Terai, Y; Senda, M; Hashizume, H; Nagashima, H; Inoue, H

    2001-01-01

    We developed a new method to measure the nerve conduction velocity of a single digital nerve. In 27 volunteers (27 hands), we separately stimulated each digital nerve on the radial and ulnar sides of the middle and ring fingers. A double-peaked potential was recorded above the median nerve at the wrist joint when either the radial-side nerve or the ulnar-side nerve of the middle finger was stimulated. The first peak of this potential had disappeared after the digital nerve was blocked under the stimulating electrodes, and the peak appeared again coinciding with the decrease of anesthesia. Shifting the stimulating electrodes on the digital nerve resulted in no significant difference in the peak conduction velocity. It is possible that each peak of the potential was attributable to conduction of an action potential along one of the two digital nerves. This new method allows the assessment of a single digital nerve, and may be clinically useful for assessing the rupture of a digital nerve and the sensory nerve action potentials in carpal tunnel syndrome.

  5. Electrical Conductivity of the Carbon Fiber Conductive Concrete

    Institute of Scientific and Technical Information of China (English)

    HOU Zuofu; LI Zhuoqiu; WANG Jianjun

    2007-01-01

    This paper discussed two methods to enhance the electrical conductivity of the carbon fiber(CF) electrically conductive concrete. The increase in the content of stone and the amount of water used to dissolve the methylcellulose and marinate the carbon fibers can decrease the electrical resistivity of the electrically conductive concrete effectively. Based on these two methods, the minimum CF content of the CF electrically conductive concrete for deicing or snow-melting application and the optimal ratio of the amount of water to dissolve the methylcellulose and marinate the carbon fibers were obtained.

  6. The Expanded Bead Size of Corneal C-Nerve Fibers Visualized by Corneal Confocal Microscopy Is Associated with Slow Conduction Velocity of the Peripheral Nerves in Patients with Type 2 Diabetes Mellitus

    Science.gov (United States)

    2016-01-01

    This study aims to establish the corneal nerve fiber (CNF) morphological alterations in a large cohort of type 2 diabetic patients and to investigate the association between the bead size, a novel parameter representing composite of accumulated mitochondria, glycogen particles, and vesicles in CNF, and the neurophysiological dysfunctions of the peripheral nerves. 162 type 2 diabetic patients and 45 healthy control subjects were studied in detail with a battery of clinical and neurological examinations and corneal confocal microscopy. Compared with controls, patients had abnormal CNF parameters. In particular the patients had reduced density and length of CNF and beading frequency and increased bead size. Alterations in CNF parameters were significant even in patients without neuropathy. The HbA1c levels were tightly associated with the bead size, which was inversely related to the motor and sensory nerve conduction velocity (NCV) and to the distal latency period of the median nerve positively. The CNF density and length positively correlated with the NCV and amplitude. The hyperglycemia-induced expansion of beads in CNF might be a predictor of slow NCV in peripheral nerves in type 2 diabetic patients. PMID:27563679

  7. Nickel coated graphite fiber conductive composites

    Energy Technology Data Exchange (ETDEWEB)

    Evans, R.E.; Hall, D.E.; Luxon, B.A.

    1986-07-01

    Nickel coated graphite (NCG) fiber, consisting of a thin continuous plating of high purity nickel over an aerospace-grade graphite core, offers performance added features by combining the lightweight and high structural reinforcement of graphite fiber with the thermal and electrical conductivity of nickel. These NCG filaments, which are composite constructions in their own right, can be processed and impregnated with thermosetting or thermoplastic resins in the same manner that graphite fiber tows are processed and impregnated to produce roving, tape or fabric prepreg. Therefore, NCG fibers can be readily integrated into structural laminate assemblies using established composites-manufacturing practices.

  8. Fiber optic flow velocity sensor based on an in-fiber integrated Michelson interferometer

    Science.gov (United States)

    Yuan, Libo; Yang, Jun; Liu, Zhihai

    2008-04-01

    A novel fiber optic flow velocity sensor based on a twin-core fiber Michelson interferometer has been proposed and demonstrated. The sensor only is a segment of twin-core fiber acting as cylinder cantilever beam. The force exerted on the cylinder by the flow of a fluid with unknown velocity bends the fiber, which corresponding to the shift of the phase of the twin-core in-fiber integrated Michelson interferometer. This twin-core fiber sensing technique could automatically compensate the variation of environmental temperature and pressure due to both arms of the interferometer would be affected equally by such changes.

  9. NUMERICAL SIMULATION ON VELOCITIES OF TWO INTERACTING FIBERS IN FIBER SUSPENSION

    Institute of Scientific and Technical Information of China (English)

    Lin Jian-zhong; Bao Fu-bing; Zhang Zhi-chao

    2003-01-01

    A mathematical model was put forward to describe the mechanical interactions of two contacting fibers, then a numerical simulation was carried out.The results of the simulation accord with experimental results well.It turns out that the initial contacting point and the initial orientation of the settling fiber have much effect on the translational and rotational velocities of the settling fiber, along with the increase in the length or the decrease in the radius of the fiber, the translational and rotational velocities of the settling fiber decrease; the same trend remains when the viscosity of the solvent increases or the density of the fiber decreases.

  10. Temperature Dependence of Sound Velocity in High-Strength Fiber-Reinforced Plastics

    Science.gov (United States)

    Nomura, Ryuji; Yoneyama, Keiichi; Ogasawara, Futoshi; Ueno, Masashi; Okuda, Yuichi; Yamanaka, Atsuhiko

    2003-08-01

    Longitudinal sound velocity in unidirectional hybrid composites or high-strength fiber-reinforced plastics (FRPs) was measured along the fiber axis over a wide temperature range (from 77 K to 420 K). We investigated two kinds of high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which are known to have negative thermal expansion coefficients and high thermal conductivities along the fiber axis. Both FRPs had very high sound velocities of about 9000 m/s at low temperatures and their temperature dependences were very strong. Sound velocity monotonically decreased with increasing temperature. The temperature dependence of sound velocity was much stronger in Dyneema-FRP than in Zylon-FRP.

  11. LONG-LASTING SUPERNORMAL CONDUCTION-VELOCITY AFTER SUSTAINED MAXIMAL ISOMETRIC CONTRACTION IN HUMAN MUSCLE

    NARCIS (Netherlands)

    VANDERHOEVEN, JH; VANWEERDEN, TW; ZWARTS, MJ

    1993-01-01

    Local muscle fatigue (1 min maximal voluntary contraction) and recovery were studied by means of surface and invasive EMG on elbow flexors to record the changes in muscle fiber conduction velocity (MFCV), median power frequency (MPF), integrated EMG (IEMG), and force. The main finding was a long-las

  12. LONG-LASTING SUPERNORMAL CONDUCTION-VELOCITY AFTER SUSTAINED MAXIMAL ISOMETRIC CONTRACTION IN HUMAN MUSCLE

    NARCIS (Netherlands)

    VANDERHOEVEN, JH; VANWEERDEN, TW; ZWARTS, MJ

    1993-01-01

    Local muscle fatigue (1 min maximal voluntary contraction) and recovery were studied by means of surface and invasive EMG on elbow flexors to record the changes in muscle fiber conduction velocity (MFCV), median power frequency (MPF), integrated EMG (IEMG), and force. The main finding was a long-las

  13. Using embedded fibers to measure explosive detonation velocities

    Energy Technology Data Exchange (ETDEWEB)

    Podsednik, Jason W.; Parks, Shawn Michael; Navarro, Rudolfo J.

    2012-07-01

    Single-mode fibers were cleverly embedded into fixtures holding nitromethane, and used in conjunction with a photonic Doppler velocimeter (PDV) to measure the associated detonation velocity. These measurements have aided us in our understanding of energetic materials and enhanced our diagnostic capabilities.

  14. Distributed optical fiber-based theoretical and empirical methods monitoring hydraulic engineering subjected to seepage velocity

    Science.gov (United States)

    Su, Huaizhi; Tian, Shiguang; Cui, Shusheng; Yang, Meng; Wen, Zhiping; Xie, Wei

    2016-09-01

    In order to systematically investigate the general principle and method of monitoring seepage velocity in the hydraulic engineering, the theoretical analysis and physical experiment were implemented based on distributed fiber-optic temperature sensing (DTS) technology. During the coupling influence analyses between seepage field and temperature field in the embankment dam or dike engineering, a simplified model was constructed to describe the coupling relationship of two fields. Different arrangement schemes of optical fiber and measuring approaches of temperature were applied on the model. The inversion analysis idea was further used. The theoretical method of monitoring seepage velocity in the hydraulic engineering was finally proposed. A new concept, namely the effective thermal conductivity, was proposed referring to the thermal conductivity coefficient in the transient hot-wire method. The influence of heat conduction and seepage could be well reflected by this new concept, which was proved to be a potential approach to develop an empirical method monitoring seepage velocity in the hydraulic engineering.

  15. Method for quantifiying conduction velocity during ventricular fibrillation

    Science.gov (United States)

    Mourad, Ayman; Nash, Martyn P.

    2007-01-01

    Velocity of propagation of electrical excitation in the heart is important for the understanding of complex arrhythmias such as ventricular fibrillation (VF). In this paper, we present a method to estimate the conduction velocity of electrical activation wavefronts that are defined to be a particular isovalue of any scalar field, such as electrical activation times, electrical phase, or indeed any other quantity that can be used to determine excitation wavefronts. This general method is based on tracking trajectories of material points that are assumed to be embedded within the wavefronts, whilst the direction of propagation is assumed to be perpendicular to the wavefront. We have derived an explicit expression for the conduction velocity in terms of the spatiotemporal gradients of the scalar field used to define wavefronts. Moreover, although it is often difficult to use activation times to compute conduction velocities during complex VF, we show that other scalar fields such as detrended voltage or electrical phase, which can faithfully represent the electrical activity during fibrillatory conduction, can be used to determine conduction velocities. We demonstrate the application of our method to determine conduction velocities from contact mapping recordings over the entire epicardial surface of the fibrillating pig heart.

  16. COMPARISON OF NERVE CONDUCTION VELOCITY IN TEENAGERS WITH DIFFERENT IQ

    Directory of Open Access Journals (Sweden)

    S KHOSRAVI

    2002-06-01

    Full Text Available Introduction. Correlation between nerve conduction velocity (NCV in peripheral and central nervous systems and intelligence has been investigated during recent years with different results. To determine whether there is any correlation between peripheral NCV and IQ, we tested median and ulnar NCV in three groups of teenagers with different IQs. Methods. 144 normal subjects aged between 12-17 years were studied in three groups. Group I, with IQ more than 120 (measured with the Wechsler intelligence test, group II, with IQ between 90-110 and group III, with IQ below 70. All three groups matched for age and sex. For each case median and ulnar NCVs were measured in sensory and motor fibers. Mean IQ in study groups were compared using ANOVA. Results. Although the range and mean values of NCV in all tested nerves are in normal ranges but there are statistically significant differences between mean NCVs between study groups. In group I (high IQ mean NCV was higher than groups II and III and mean NCV in group III was less than groups I and II (p<0.05. IQ and NCV were not significantly different in girls and boys (p>0.05. Discussion .It is well established that IQ is a multi-factorial parameter and genetic, environment, hormones and individual physical factors such as size and volume of brain could influence intelligence. This study showed statistically difference between IQ and peripheral NCV in adolescents aged 12-17 years. Investigation of correlation between IQ, NCV and other evoked potentials in different age groups is suggested.

  17. Determinants and clinical application of muscle fibre conduction velocity

    NARCIS (Netherlands)

    Blijham, P.J.

    2007-01-01

    A muscle fibre can be excited by electrical stimulation using a needle electrode. Action potentials elicited this way will be conducted through the muscle fibre and can be recorded at some distance with a second needle electrode. This way, muscle fibre conduction velocity can be estimated. In the pr

  18. Correlation Function Analysis of Fiber Networks: Implications for Thermal Conductivity

    Science.gov (United States)

    Martinez-Garcia, Jorge; Braginsky, Leonid; Shklover, Valery; Lawson, John W.

    2011-01-01

    The heat transport in highly porous fiber structures is investigated. The fibers are supposed to be thin, but long, so that the number of the inter-fiber connections along each fiber is large. We show that the effective conductivity of such structures can be found from the correlation length of the two-point correlation function of the local conductivities. Estimation of the parameters, determining the conductivity, from the 2D images of the structures is analyzed.

  19. Soft capacitor fibers using conductive polymers for electronic textiles

    Science.gov (United States)

    Gu, Jian Feng; Gorgutsa, Stephan; Skorobogatiy, Maksim

    2010-11-01

    A novel, highly flexible, conductive polymer-based fiber with high electric capacitance is reported. In its cross section the fiber features a periodic sequence of hundreds of conductive and isolating plastic layers positioned around metallic electrodes. The fiber is fabricated using the fiber drawing method, where a multi-material macroscopic preform is drawn into a sub-millimeter capacitor fiber in a single fabrication step. Several kilometers of fibers can be obtained from a single preform with fiber diameters ranging between 500 and 1000 µm. A typical measured capacitance of our fibers is 60-100 nF m-1 and it is independent of the fiber diameter. Analysis of the fiber frequency response shows that in its simplest interrogation mode the capacitor fiber has a transverse resistance of 5 kΩ m L-1, which is inversely proportional to the fiber length L and is independent of the fiber diameter. Softness of the fiber materials, the absence of liquid electrolyte in the fiber structure, ease of scalability to large production volumes and high capacitance of our fibers make them interesting for various smart textile applications ranging from distributed sensing to energy storage.

  20. Calculation of the conduction velocity of short nerve fibres

    NARCIS (Netherlands)

    van der Vliet, G.H.; Holsheimer, J.

    1980-01-01

    The conduction velocity v of a nerve fibre is calculated from the time delay Δ of a propagating action potential between two recording sites along the fibre. However, the conventional method of determining Δ cannot be applied to short nerve fibres. Therefore several linear signal analysis methods

  1. The Radial Velocity Precision of Fiber-fed Spectrographs

    CERN Document Server

    Walker, G A H; Bohlender, D A; Yang, S; Walker, Gordon A.H.; Shkolnik, Evgenya; Bohlender, David A.; Yang, Stephenson

    2003-01-01

    We have measured the radial velocities of five 51 Peg-type stars and one star with constant velocity. Our measurements, on 20 \\AA centered at 3947 \\AA, were conventional using Th/Ar comparison spectra taken every 20 or 40 minutes between the stellar exposures. Existing IRAF routines were used for the reduction. We find $\\sigma_{RV}$ $\\leq$ 20 m s$^{-1}$, provided 4 measurements (out of 72) with residuals $>5\\sigma_{RV}$ are neglected. The observations were made with the CFHT Gecko spectrograph, fiber-fed with the CAFE system (R$\\sim$110,000). $\\sigma_{RV}$ $\\leq$10 m s$^{-1}$ seems possible with additional care. This study was incidental to the main program and so not exhaustive but the small value of $\\sigma_{RV}$ implies that the fiber feed/image slicer system on Gecko + CAFE, essentially eliminates the long standing problem of guiding errors in radial velocity measurements. We are not suggesting this conventional approach for serious Doppler planet searches (especially with Gecko which has such a small mul...

  2. Carbon nanotube and graphene nanoribbon-coated conductive Kevlar fibers.

    Science.gov (United States)

    Xiang, Changsheng; Lu, Wei; Zhu, Yu; Sun, Zhengzong; Yan, Zheng; Hwang, Chi-Chau; Tour, James M

    2012-01-01

    Conductive carbon material-coated Kevlar fibers were fabricated through layer-by-layer spray coating. Polyurethane was used as the interlayer between the Kevlar fiber and carbon materials to bind the carbon materials to the Kevlar fiber. Strongly adhering single-walled carbon nanotube coatings yielded a durable conductivity of 65 S/cm without significant mechanical degradation. In addition, the properties remained stable after bending or water washing cycles. The coated fibers were analyzed using scanning electron microcopy and a knot test. The as-produced fiber had a knot efficiency of 23%, which is more than four times higher than that of carbon fibers. The spray-coating of graphene nanoribbons onto Kevlar fibers was also investigated. These flexible coated-Kevlar fibers have the potential to be used for conductive wires in wearable electronics and battery-heated armors.

  3. Dynamic Modulation of Myelination in Response to Visual Stimuli Alters Optic Nerve Conduction Velocity

    Science.gov (United States)

    Etxeberria, Ainhoa; Hokanson, Kenton C.; Dao, Dang Q.; Mayoral, Sonia R.; Mei, Feng; Redmond, Stephanie A.; Ullian, Erik M.

    2016-01-01

    Myelin controls the time required for an action potential to travel from the neuronal soma to the axon terminal, defining the temporal manner in which information is processed within the CNS. The presence of myelin, the internodal length, and the thickness of the myelin sheath are powerful structural factors that control the velocity and fidelity of action potential transmission. Emerging evidence indicates that myelination is sensitive to environmental experience and neuronal activity. Activity-dependent modulation of myelination can dynamically alter action potential conduction properties but direct functional in vivo evidence and characterization of the underlying myelin changes is lacking. We demonstrate that in mice long-term monocular deprivation increases oligodendrogenesis in the retinogeniculate pathway but shortens myelin internode lengths without affecting other structural properties of myelinated fibers. We also demonstrate that genetically attenuating synaptic glutamate neurotransmission from retinal ganglion cells phenocopies the changes observed after monocular deprivation, suggesting that glutamate may constitute a signal for myelin length regulation. Importantly, we demonstrate that visual deprivation and shortened internodes are associated with a significant reduction in nerve conduction velocity in the optic nerve. Our results reveal the importance of sensory input in the building of myelinated fibers and suggest that this activity-dependent alteration of myelination is important for modifying the conductive properties of brain circuits in response to environmental experience. SIGNIFICANCE STATEMENT Oligodendrocyte precursor cells differentiate into mature oligodendrocytes and are capable of ensheathing axons with myelin without molecular cues from neurons. However, this default myelination process can be modulated by changes in neuronal activity. Here, we show, for the first time, that experience-dependent activity modifies the length of myelin

  4. Soft capacitor fibers using conductive polymers for electronic textiles

    CERN Document Server

    Gu, Jian Feng; Skorobogatiy, Maksim

    2010-01-01

    A novel, highly flexible, conductive polymer-based fiber with high electric capacitance is reported. In its crossection the fiber features a periodic sequence of hundreds of conductive and isolating plastic layers positioned around metallic electrodes. The fiber is fabricated using fiber drawing method, where a multi-material macroscopic preform is drawn into a sub-millimeter capacitor fiber in a single fabrication step. Several kilometres of fibers can be obtained from a single preform with fiber diameters ranging between 500um -1000um. A typical measured capacitance of our fibers is 60-100 nF/m and it is independent of the fiber diameter. For comparison, a coaxial cable of the comparable dimensions would have only ~0.06nF/m capacitance. Analysis of the fiber frequency response shows that in its simplest interrogation mode the capacitor fiber has a transverse resistance of 5 kOhm/L, which is inversely proportional to the fiber length L and is independent of the fiber diameter. Softness of the fiber materials...

  5. Interstitial volume modulates the conduction velocity-gap junction relationship.

    Science.gov (United States)

    Veeraraghavan, Rengasayee; Salama, Mohamed E; Poelzing, Steven

    2012-01-01

    Cardiac conduction through gap junctions is an important determinant of arrhythmia susceptibility. Yet, the relationship between degrees of G(j) uncoupling and conduction velocity (θ) remains controversial. Conflicting results in similar experiments are normally attributed to experimental differences. We hypothesized that interstitial volume modulates conduction velocity and its dependence on G(j). Interstitial volume (V(IS)) was quantified histologically from guinea pig right ventricle. Optical mapping was used to quantify conduction velocity and anisotropy (AR(θ)). Albumin (4 g/l) decreased histologically assessed V(IS), increased transverse θ by 71 ± 10%, and lowered AR(θ). Furthermore, albumin did not change isolated cell size. Conversely, mannitol increased V(IS), decreased transverse θ by 24 ± 4%, and increased AR(θ). Mannitol also decreased cell width by 12%. Furthermore, mannitol was associated with spontaneous ventricular tachycardias in three of eight animals relative to zero of 15 during control. The θ-G(j) relationship was assessed using the G(j) uncoupler carbenoxolone (CBX). Whereas 13 μM CBX did not significantly affect θ during control, it slowed transverse θ by 38 ± 9% during mannitol (edema). These data suggest changes in V(IS) modulate θ, AR(θ), and the θ-G(j) relationship and thereby alter arrhythmia susceptibility. Therefore, V(IS) may underlie arrhythmia susceptibility, particularly in diseases associated with gap junction remodeling.

  6. Estimation of circumferential fiber shortening velocity by echocardiography.

    Science.gov (United States)

    Ruschhaupt, D G; Sodt, P C; Hutcheon, N A; Arcilla, R A

    1983-07-01

    The M-mode and two-dimensional echocardiograms of 40 young patients were analyzed to compare the mean circumferential fiber shortening velocity (Vcf) of the left ventricle calculated separately by two methods. The mean circumferential fiber shortening velocity was derived from the M-mode echocardiogram as minor axis shortening/ejection time and derived from the two-dimensional echocardiogram as actual circumference change/ejection time. With computer assistance, circumference was determined from the short-axis two-dimensional echocardiographic images during end-diastole and end-systole. Good correlations were obtained between the left ventricular diameter derived by M-mode echocardiography and the vertical axis during end-diastole (r = 0.79) and end-systole (r = 0.88) derived by two-dimensional echocardiography. Likewise, high correlations were noted between diameter and circumference in end-diastole (r = 0.89) and end-systole (r = 0.88). However, comparison of Vcf obtained by M-mode echocardiography with that obtained by two-dimensional echocardiography showed only fair correlation (r = 0.68). Moreover, the diameter/circumference ratio determined in end-diastole and end-systole differed significantly (p less than 0.001), possibly owing to the change in geometry of the ventricular sector image during systole. Although Vcf derived by M-mode echocardiography is a useful index of left ventricular performance, it does not truly reflect the circumference change during systole.

  7. Rotigaptide (ZP123) reverts established atrial conduction velocity slowing.

    Science.gov (United States)

    Haugan, Ketil; Kjølbye, Anne Louise; Hennan, James K; Petersen, Jørgen Søberg

    2005-01-01

    Rotigaptide (ZP123) increases gap junction intercellular communication (GJIC) and prevents stress-induced cardiac conduction velocity (CV) slowing. However, the effect of rotigaptide on established cardiac conduction slowing and the duration of effect on rotigaptide during washout is unknown. Metabolic stress (induced by superfusion with nonoxygenated glucose-free Tyrodes buffer) was associated with a 30% decrease in atrial CV in vehicle-treated rat atria. Rotigaptide treatment initiated after a period of 30 minutes of metabolic stress produced a rapid and significant increase in CV compared to vehicle-treated time controls. During washout of rotigaptide for 30 min (while subjected to metabolic stress), there was a minor decrease in atrial CV; however, this was not significantly different from atrial CV in a rotigaptide-treated time control group. Rotigaptide treatment rapidly normalizes established conduction slowing in atria subjected to metabolic stress. However, the cessation of effect was considerably slower than the onset of action.

  8. [Comparison of force and shortening velocity in fast and slow rabbit muscle fibers at different temperatures].

    Science.gov (United States)

    Kochubeĭ, P V; Bershitskiĭ, S Iu

    2014-01-01

    The temperature dependence of force, maximal shortening velocity and power of maximally activated single permeabilized fibers from fast and slow muscles of the rabbit were recorded in a temperature range from 10 to 35 degrees C with 5 degrees C step. It was found that temperature dependence of force of both types of fibers is identical. Averaged maximal shortening velocity in the slow fibers, unlike the fast fibers, had no statistically significant temperature dependence that is not in agreement with the data obtained on intact rat muscle fibers and in an in vitro motility assay. However maximal shortening velocity in each individual slow fiber did depend on temperature. The temperature dependence of power of the slow fibers was lower than that of the fast ones. Because of large data scattering the average temperature dependence of power of the slow fibers was significantly lower than that in individual slow fibers.

  9. Thermal conductivity, electrical conductivity and specific heat of copper-carbon fiber composite

    Science.gov (United States)

    Kuniya, Keiichi; Arakawa, Hideo; Kanai, Tsuneyuki; Chiba, Akio

    1988-01-01

    A new material of copper/carbon fiber composite is developed which retains the properties of copper, i.e., its excellent electrical and thermal conductivity, and the property of carbon, i.e., a small thermal expansion coefficient. These properties of the composite are adjustable within a certain range by changing the volume and/or the orientation of the carbon fibers. The effects of carbon fiber volume and arrangement changes on the thermal and electrical conductivity, and specific heat of the composite are studied. Results obtained are as follows: the thermal and electrical conductivity of the composite decrease as the volume of the carbon fiber increases, and were influenced by the fiber orientation. The results are predictable from a careful application of the rule of mixtures for composites. The specific heat of the composite was dependent, not on fiber orientation, but on fiber volume. In the thermal fatigue tests, no degradation in the electrical conductivity of this composite was observed.

  10. CHIRON - A Fiber Fed Spectrometer for Precise Radial Velocities

    CERN Document Server

    Tokovinin, Andrei; Bonati, Marco; Giguere, Matthew J; Moore, Peter; Schwab, Christian; Spronck, Julien F P; Szymkowiak, Andrew

    2013-01-01

    The CHIRON optical high-resolution echelle spectrometer was commissioned at the 1.5m telescope at CTIO in 2011. The instrument was designed for high throughput and stability, with the goal of monitoring radial velocities of bright stars with high precision and high cadence for the discovery of low-mass exoplanets. Spectral resolution of R=79,000 is attained when using a slicer with a total (including telescope and detector) efficiency of 6% or higher, while a resolution of R=136,000 is available for bright stars. A fixed spectral range of 415 to 880 nm is covered. The echelle grating is housed in a vacuum enclosure and the instrument temperature is stabilized to +-0.2deg. Stable illumination is provided by an octagonal multimode fiber with excellent light-scrambling properties. An iodine cell is used for wavelength calibration. We describe the main optics, fiber feed, detector, exposure-meter, and other aspects of the instrument, as well as the observing procedure and data reduction.

  11. Fabrication of highly conductive carbon nanotube fibers for electrical application

    Science.gov (United States)

    Guo, Fengmei; Li, Can; Wei, Jinquan; Xu, Ruiqiao; Zhang, Zelin; Cui, Xian; Wang, Kunlin; Wu, Dehai

    2015-09-01

    Carbon nanotubes (CNTs) have great potential for use as electrical wires because of their outstanding electrical and mechanical properties. Here, we fabricate lightweight CNT fibers with electrical conductivity as high as that of stainless steel from macroscopic CNT films by drawing them through diamond wire-drawing dies. The entangled CNT bundles are straightened by suffering tension, which improves the alignment of the fibers. The loose fibers are squeezed by the diamond wire-drawing dies, which reduces the intertube space and contact resistance. The CNT fibers prepared by drawing have an electrical conductivity as high as 1.6 × 106 s m-1. The fibers are very stable when kept in the air and under cyclic tensile test. A prototype of CNT motor is demonstrated by replacing the copper wires with the CNT fibers.

  12. Arc Conductance and Flow Velocity Affected by Transient Recovery Voltage

    Science.gov (United States)

    Fukuoka, Reo; Ishikawa, Yuya; Ono, Seisui; Sato, Ken; Yamamoto, Shinji; Iwao, Toru

    2016-09-01

    Recently, the stable supply of electric power is indispensable. The GCB (Gas Circuit Breaker) can prevent the spread of the fault current. However, it should have the reliability more. Therefore the GCB has been researched for performance improvement of the arc interruption of abnormal fault current without the fail. Therefore, it is important to prevent the breakdown such as the re-ignition and thermal re-ignition of arc after the arc interruption. It is necessary to reduce the arc conductance in order to prevent the re-ignition of arc. The arc conductance is derived from the temperature distribution and the volume of the arc. The temperature distribution of the arc is formed by convection. In this research, the arc conductance and flow velocity affected by transient recovery voltage are elucidated. The flow rate and temperature distribution of the arc is calculated with changing transient recovery voltage. In addition, the arc conductance is calculated in order to know the extinguish arc ability. As a result, when the transient recovery voltage increases, the probability of re-ignition increases. Therefore, the arc temperature and the arc conductance were increased.

  13. Induction heating of mastic containing conductive fibers and fillers

    NARCIS (Netherlands)

    García, Á.; Schlangen, E.; Ven, M. van de; Vliet, D. van

    2011-01-01

    The objective of this research is to examine the induction heating of mastic through the addition of electrically conductive fillers and fibers (graphite and steel wool), and to prove that this material can be healed with induction energy. The effect of fibers content, sand-bitumen ratio and the com

  14. Induction heating of mastic containing conductive fibers and fillers

    NARCIS (Netherlands)

    García, Á.; Schlangen, E.; Van de Ven, M.; Van Vliet, D.

    The objective of this research is to examine the induction heating of mastic through the addition of electrically conductive fillers and fibers (graphite and steel wool), and to prove that this material can be healed with induction energy. The effect of fibers content, sand–bitumen ratio and the com

  15. System and method for determining velocity of electrically conductive fluid

    Science.gov (United States)

    Polzin, Kurt A. (Inventor); Korman, Valentin (Inventor); Markusic, Thomas E. (Inventor); Stanojev, Boris Johann (Inventor)

    2008-01-01

    A flowing electrically-conductive fluid is controlled between an upstream and downstream location thereof to insure that a convection timescale of the flowing fluid is less than a thermal diffusion timescale of the flowing fluid. First and second nodes of a current-carrying circuit are coupled to the fluid at the upstream location. A current pulse is applied to the current-carrying circuit so that the current pulse travels through the flowing fluid to thereby generate a thermal feature therein at the upstream location. The thermal feature is convected to the downstream location where it is monitored to detect a peak associated with the thermal feature so-convected. The velocity of the fluid flow is determined using a time-of-flight analysis.

  16. Motor Nerve Conduction Velocity In Postmenopausal Women with Peripheral Neuropathy

    Science.gov (United States)

    Asif, Naiyer; Singh, Paras Nath; Hossain, Mohd Mobarak

    2016-01-01

    Introduction The post-menopausal phase is characterized by a decline in the serum oestrogen and progesterone levels. This phase is also associated with higher incidence of peripheral neuropathy. Aim To explore the relationship between the peripheral motor nerve status and serum oestrogen and progesterone levels through assessment of Motor Nerve Conduction Velocity (MNCV) in post-menopausal women with peripheral neuropathy. Materials and Methods This cross-sectional study was conducted at Jawaharlal Nehru Medical College during 2011-2013. The study included 30 post-menopausal women with peripheral neuropathy (age: 51.4±7.9) and 30 post-menopausal women without peripheral neuropathy (control) (age: 52.5±4.9). They were compared for MNCV in median, ulnar and common peroneal nerves and serum levels of oestrogen and progesterone estimated through enzyme immunoassays. To study the relationship between hormone levels and MNCV, a stepwise linear regression analysis was done. Results The post-menopausal women with peripheral neuropathy had significantly lower MNCV and serum oestrogen and progesterone levels as compared to control subjects. Stepwise linear regression analysis showed oestrogen with main effect on MNCV. Conclusion The findings of the present study suggest that while the post-menopausal age group is at a greater risk of peripheral neuropathy, it is the decline in the serum estrogen levels which is critical in the development of peripheral neuropathy. PMID:28208850

  17. Motor unit action potential conduction velocity estimated from surface electromyographic signals using image processing techniques.

    Science.gov (United States)

    Soares, Fabiano Araujo; Carvalho, João Luiz Azevedo; Miosso, Cristiano Jacques; de Andrade, Marcelino Monteiro; da Rocha, Adson Ferreira

    2015-09-17

    In surface electromyography (surface EMG, or S-EMG), conduction velocity (CV) refers to the velocity at which the motor unit action potentials (MUAPs) propagate along the muscle fibers, during contractions. The CV is related to the type and diameter of the muscle fibers, ion concentration, pH, and firing rate of the motor units (MUs). The CV can be used in the evaluation of contractile properties of MUs, and of muscle fatigue. The most popular methods for CV estimation are those based on maximum likelihood estimation (MLE). This work proposes an algorithm for estimating CV from S-EMG signals, using digital image processing techniques. The proposed approach is demonstrated and evaluated, using both simulated and experimentally-acquired multichannel S-EMG signals. We show that the proposed algorithm is as precise and accurate as the MLE method in typical conditions of noise and CV. The proposed method is not susceptible to errors associated with MUAP propagation direction or inadequate initialization parameters, which are common with the MLE algorithm. Image processing -based approaches may be useful in S-EMG analysis to extract different physiological parameters from multichannel S-EMG signals. Other new methods based on image processing could also be developed to help solving other tasks in EMG analysis, such as estimation of the CV for individual MUs, localization and tracking of innervation zones, and study of MU recruitment strategies.

  18. Transparent and conductive paper from nanocellulose fibers

    KAUST Repository

    Hu, Liangbing

    2013-01-01

    Here we report on a novel substrate, nanopaper, made of cellulose nanofibrils, an earth abundant material. Compared with regular paper substrates, nanopaper shows superior optical properties. We have carried out the first study on the optical properties of nanopaper substrates. Since the size of the nanofibrils is much less than the wavelength of visible light, nanopaper is highly transparent with large light scattering in the forward direction. Successful depositions of transparent and conductive materials including tin-doped indium oxide, carbon nanotubes and silver nanowires have been achieved on nanopaper substrates, opening up a wide range of applications in optoelectronics such as displays, touch screens and interactive paper. We have also successfully demonstrated an organic solar cell on the novel substrate. © The Royal Society of Chemistry 2013.

  19. Force-Velocity and Power Characteristics of Rat Soleus Muscle Fibers after Hindlimb Suspension

    Science.gov (United States)

    McDonald, K. S.; Blaser, C. A.; Fitts, R. H.

    1994-01-01

    The effects of 1, 2, and 3 wk of Hindlimb Suspension (HS) on force-velocity and power characteristics of single rat soleus fibers were determined. After 1, 2, or 3 wk of HS, small fiber bundles were isolated, placed in skinning solution, and stored at -20 C until studied. Single fibers were isolated and placed between a motor arm and force transducer, functional properties were studied, and fiber protein content was subsequently analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Additional fibers were isolated from soleus of control and after 1 and 3 wk of HS, and fiber type distribution and myosin light chain stoichiometry were determined from SDS-PAGE analysis. After 1 wk of HS, percent type I fibers declined from 82 to 74%, whereas hybrid fibers increased from 10 to 18%. Percent fast type 11 fibers increased from 8% in control and 1 wk of HS to 26% by 3 wk of HS. Most fibers showed an increased unloaded maximal shortening velocity (V(sub 0)), but myosin heavy chain remained entirely slow type I. The mechanism for increased V(sub 0) is unknown. There was a progressive decrease in fiber diameter (14, 30, and 38%) and peak force (38, 56, and 63%) after 1, 2, and 3 wk of HS, respectively. One week of HS resulted in a shift of the force-velocity curve, and between 2 and 3 wk of HS the curve shifted further such that V(sub 0) was higher than control at all relative loads less than 45% peak isometric force. Peak absolute power output of soleus fibers progressively decreased through 2 wk of HS but showed no further change at 3 wk. The results suggest that between 2 and 3 wk the HS-induced alterations in the force-velocity relationship act to maintain the power output of single soleus fibers despite a continued reduction in fiber force.

  20. Determinants of myocardial conduction velocity: implications for arrhythmogenesis.

    Directory of Open Access Journals (Sweden)

    James Harmsworth King

    2013-06-01

    Full Text Available Slowed myocardial conduction velocity (θ is associated with an increased risk of re-entrant excitation, predisposing to cardiac arrhythmia. θ is determined by the ion channel and physical properties of cardiac myocytes and by their interconnections. Thus, θ is closely related to the maximum rate of action potential (AP depolarisation ((dV/dtmax, as determined by the fast Na+ current (INa; the axial resistance (ra to local circuit current flow between cells; their membrane capacitances (cm; and to the geometrical relationship between successive myocytes within cardiac tissue. These determinants are altered by a wide range of pathophysiological conditions. Firstly, INa is reduced by the impaired Na+ channel function that arises clinically during heart failure, ischaemia, tachycardia, and following treatment with class I antiarrhythmic drugs. Such reductions also arise as a consequence of mutations in SCN5A such as those occurring in Lenègre disease, Brugada syndrome, sick sinus syndrome, and atrial fibrillation (AF. Secondly, ra, may be increased due to gap junction decoupling following ischaemia, ventricular hypertrophy and heart failure, or as a result of mutations in CJA5 found in idiopathic AF and atrial standstill. Finally, either ra or cm could potentially be altered by fibrotic change through the resultant decoupling of myocyte-myocyte connections and coupling of myocytes with fibroblasts. Such changes are observed in myocardial infarction and cardiomyopathy or following mutations in MHC403 and SCN5A resulting in hypertrophic cardiomyopathy or Lenègre disease respectively. This review defines and quantifies the determinants of θ and summarises experimental evidence that links changes in these determinants with reduced myocardial θ and arrhythmogenesis. It thereby identifies the diverse pathophysiological conditions in which abnormal θ may contribute to arrhythmia.

  1. A new heat propagation velocity prevails over Brownian particle velocities in determining the thermal conductivities of nanofluids

    Directory of Open Access Journals (Sweden)

    Chon Chan

    2011-01-01

    Full Text Available Abstract An alternative insight is presented concerning heat propagation velocity scales in predicting the effective thermal conductivities of nanofluids. The widely applied Brownian particle velocities in published literature are often found too slow to describe the relatively higher nanofluid conductivities. In contrast, the present model proposes a faster heat transfer velocity at the same order as the speed of sound, rooted in a modified kinetic principle. In addition, this model accounts for both nanoparticle heat dissipation as well as coagulation effects. This novel model of effective thermal conductivities of nanofluids agrees well with an extended range of experimental data.

  2. Verification and Validation of Carbon-Fiber Laminate Low Velocity Impact Simulations.

    Energy Technology Data Exchange (ETDEWEB)

    English, Shawn Allen; Nelson, Stacy Michelle; Briggs, Timothy; Brown, Arthur A.

    2014-10-01

    Presented is a model verification and validation effort using low - velocity impact (LVI) of carbon fiber reinforced polymer laminate experiments. A flat cylindrical indenter impacts the laminate with enough energy to produce delamination, matrix cracks and fiber breaks. Included in the experimental efforts are ultrasonic scans of the damage for qualitative validation of the models. However, the primary quantitative metrics of validation are the force time history measured through the instrumented indenter and initial and final velocities. The simulations, whi ch are run on Sandia's Sierra finite element codes , consist of all physics and material parameters of importance as determined by a sensitivity analysis conducted on the LVI simulation. A novel orthotropic damage and failure constitutive model that is cap able of predicting progressive composite damage and failure is described in detail and material properties are measured, estimated from micromechanics or optimized through calibration. A thorough verification and calibration to the accompanying experiment s are presented. Specia l emphasis is given to the four - point bend experiment. For all simulations of interest, the mesh and material behavior is verified through extensive convergence studies. An ensemble of simulations incorporating model parameter unc ertainties is used to predict a response distribution which is then compared to experimental output. The result is a quantifiable confidence in material characterization and model physics when simulating this phenomenon in structures of interest.

  3. Comparison of the effects of stimulating groups of static gamma axons with different conduction velocity ranges on cat spindles.

    Science.gov (United States)

    Emonet-Dénand, F; Laporte, Y; Petit, J

    2001-07-01

    In cat peroneus tertius muscles, static gamma axons were prepared in groups of three to four according to the conduction velocity of their axons (fast, intermediate, or slow). Effects of stimulating these groups (at 20, 30, and 50 Hz) on spindle ensemble discharges during sinusoidal stretch (peak-to-peak amplitude, 0.5 mm; frequency linearly increasing from 0.5 to 8 Hz in 10 s) were compared. Ensemble discharges were obtained by digital treatment of the discharges in afferent fibers from all the spindles in peroneus tertius as recorded from the muscle nerve. Stimulation of each group prevented ensemble discharges from falling to very low levels during shortening phases. However, this effect was clearly larger when the group of fast-conducting axons was stimulated. In view of the known effects of the activation of bag(2) and chain fibers (either separately or together) on single primary ending discharges during comparable sinusoidal stretches, this stronger effect supports the view that static gamma axons with faster conduction velocities are more likely to supply more bag(2) fibers than slower ones. Possibly the proportions of bag(2) and chain fibers activated during motor activity are determined by a recruitment of static gamma motoneurons related to their size.

  4. Electromagnetic interference shielding effectiveness of polypropylene/conducting fiber composites

    Science.gov (United States)

    Lee, Pyoung-Chan; Kim, Bo-Ram; Jeoung, Sun Kyoung; Kim, Yeung Keun

    2016-03-01

    Electromagnetic released from the automotive electronic parts is harmful to human body. Electromagnetic interference (EMT) shielding refers to the reflection and/or adsorption of electromagnetic radiation by a material, which thereby acts as a shield against the penetration of the radiation through the shield. Polypropylene (PP)/conductive micro fiber composites containing various fiber contents and fiber length were injection-molded. The effect of fiber content and length on electrical properties of the composites was studied by electrical resistivity and EMT shielding measurements. The through-plane electrical conductivity and dielectric permittivity were obtained by measuring dielectric properties. The EMT shielding effectiveness (SE) was investigated by using S-parameter in the range of 100 ~ 1500 MHz. Reflection, absorption and multiple-reflection are the EMT attenuation mechanisms. From the measurement of S-Parameters, the absorption coefficient, reflection coefficient, and the shielding efficiency of the materials were calculated. The EMT SE of PP/conducing fiber composites is 40 dB over a wide frequency range up to 1.5 GHz, which is higher than that of PP/talc composite used automotive parts, viz. 0 dB.

  5. Electromagnetic interference shielding effectiveness of polypropylene/conducting fiber composites

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Pyoung-Chan, E-mail: pclee@katech.re.kr; Kim, Bo-Ram; Jeoung, Sun Kyoung [Korea Automotive Technology lnstitute, Dongnam-Gu, Chonan-Si, Chungnam 330-912 (Korea, Republic of); Kim, Yeung Keun [Win& Win Co., Ltd., Anseong-Si, Gyeonggi-Do, 456-931 (Korea, Republic of)

    2016-03-09

    Electromagnetic released from the automotive electronic parts is harmful to human body. Electromagnetic interference (EMT) shielding refers to the reflection and/or adsorption of electromagnetic radiation by a material, which thereby acts as a shield against the penetration of the radiation through the shield. Polypropylene (PP)/conductive micro fiber composites containing various fiber contents and fiber length were injection-molded. The effect of fiber content and length on electrical properties of the composites was studied by electrical resistivity and EMT shielding measurements. The through-plane electrical conductivity and dielectric permittivity were obtained by measuring dielectric properties. The EMT shielding effectiveness (SE) was investigated by using S-parameter in the range of 100 ~ 1500 MHz. Reflection, absorption and multiple-reflection are the EMT attenuation mechanisms. From the measurement of S-Parameters, the absorption coefficient, reflection coefficient, and the shielding efficiency of the materials were calculated. The EMT SE of PP/conducing fiber composites is 40 dB over a wide frequency range up to 1.5 GHz, which is higher than that of PP/talc composite used automotive parts, viz. 0 dB.

  6. Group-velocity matched nonlinear photonic crystal fibers

    DEFF Research Database (Denmark)

    Bache, Morten; Lægsgaard, Jesper; Bang, Ole

    2006-01-01

    A quadratic nonlinear index-guiding silica PCF is optimized for efficient second-harmonic generation through dispersion calculations. Zero group-velocity mismatch is possible for any pump wavelength above 780 nm. Very high conversion efficiencies and bandwidths are found.......A quadratic nonlinear index-guiding silica PCF is optimized for efficient second-harmonic generation through dispersion calculations. Zero group-velocity mismatch is possible for any pump wavelength above 780 nm. Very high conversion efficiencies and bandwidths are found....

  7. Muscle fiber conduction abnormalities in early diabetic polyneuropathy

    NARCIS (Netherlands)

    Meijer, J. W. G.; Lange, F.; Links, T. P.; van der Hoeven, J. H.

    2008-01-01

    Objective: Diabetic polyneuropathy (PNP) has been proposed to be a primary disorder of sensory nerves. At an early stage motor nerve conduction velocity (MNCV) and muscle strength remain preserved due to compensatory mechanisms (axonal sprouting, reinnervation). We evaluated the use of invasive musc

  8. Fiber type composition and maximum shortening velocity of muscles crossing the human shoulder.

    Science.gov (United States)

    Srinivasan, R C; Lungren, M P; Langenderfer, J E; Hughes, R E

    2007-03-01

    A study of the fiber type composition of fourteen muscles spanning the human glenohumeral joint was carried out with the purpose of determining the contribution of fiber types to overall muscle cross-sectional area (CSA) and to estimate the maximum shortening velocity (V(max)) of those muscles. Muscle biopsies were procured from 4 male cadavers (mean age 50) within 24 hr of death, snap frozen, mounted, and transversely sectioned (10 microm). Slides were stained for myofibrillar ATPase after alkaline preincubation. Photoimages were taken of defined areas (100 fibers) using the Bioquant system, and fiber type and CSA were measured from these images. Staining for mATPase produced three different fiber types: slow-oxidative (SO), fast-oxidative-glycolytic (FOG), and fast-glycolytic (FG). On average, the muscle fiber type composition ranged from 22 to 40% of FG, from 17 to 51% of FOG, and from 23 to 56% of SO. Twelve out of the 14 muscles had average SO proportions ranging from 35 to 50%. V(max) was calculated from the fiber type contribution relative to CSA and shortening velocity values taken from the literature. The maximum velocities of shortening presented here provide a physiological basis for the development of human shoulder musculoskeletal models suitable for predicting muscle forces for functionally relevant tasks encompassing conditions of muscle shortening and lengthening.

  9. Embedded Fiber Optic Probes to Measure Detonation Velocities Using the Photonic Doppler Velocimeter

    Energy Technology Data Exchange (ETDEWEB)

    Hare, D E; Holtkamp, D B; Strand, O T

    2010-03-02

    Detonation velocities for high explosives can be in the 7 to 8 km/s range. Previous work has shown that these velocities may be measured by inserting an optical fiber probe into the explosive assembly and recording the velocity time history using a Fabry-Perot velocimeter. The measured velocity using this method, however, is the actual velocity multiplied times the refractive index of the fiber core, which is on the order of 1.5. This means that the velocimeter diagnostic must be capable of measuring velocities as high as 12 km/s. Until recently, a velocity of 12 km/s was beyond the maximum velocity limit of a homodyne-based velocimeter. The limiting component in a homodyne system is usually the digitizer. Recently, however, digitizers have come on the market with 20 GHz bandwidth and 50 GS/s sample rate. Such a digitizer coupled with high bandwidth detectors now have the total bandwidth required to make velocity measurements in the 12 km/s range. This paper describes measurements made of detonation velocities using a high bandwidth homodyne system.

  10. AN EFFICIENT, COMPACT, AND VERSATILE FIBER DOUBLE SCRAMBLER FOR HIGH PRECISION RADIAL VELOCITY INSTRUMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath; Ramsey, Lawrence; Levi, Eric; Schwab, Christian; Hearty, Fred [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); MacDonald, Nick, E-mail: shalverson@psu.edu, E-mail: aur17@psu.edu [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States)

    2015-06-10

    We present the design and test results of a compact optical fiber double-scrambler for high-resolution Doppler radial velocity instruments. This device consists of a single optic: a high-index n ∼ 2 ball lens that exchanges the near and far fields between two fibers. When used in conjunction with octagonal fibers, this device yields very high scrambling gains (SGs) and greatly desensitizes the fiber output from any input illumination variations, thereby stabilizing the instrument profile of the spectrograph and improving the Doppler measurement precision. The system is also highly insensitive to input pupil variations, isolating the spectrograph from telescope illumination variations and seeing changes. By selecting the appropriate glass and lens diameter the highest efficiency is achieved when the fibers are practically in contact with the lens surface, greatly simplifying the alignment process when compared to classical double-scrambler systems. This prototype double-scrambler has demonstrated significant performance gains over previous systems, achieving SGs in excess of 10,000 with a throughput of ∼87% using uncoated Polymicro octagonal fibers. Adding a circular fiber to the fiber train further increases the SG to >20,000, limited by laboratory measurement error. While this fiber system is designed for the Habitable-zone Planet Finder spectrograph, it is more generally applicable to other instruments in the visible and near-infrared. Given the simplicity and low cost, this fiber scrambler could also easily be multiplexed for large multi-object instruments.

  11. Electromagnetic scattering and absorption by a finite conducting thin fiber

    Science.gov (United States)

    Alyones, Sharhabeel Saleh

    Scattering, absorption and extinction by a thin finite length conducting wire are computed numerically by solving the Generalized Pocklington integro-differential equation using two distinct approaches: the Method of Moments and the Galerkin method. The former employs discretization of the wire and the latter uses Legendre polynomials as basis functions with modifications to satisfy the boundary conditions of the problem. A new development included in the computations to be reported here involves a more accurate rendering of wires with lower aspect (length-to-diameter) ratios. Both methods converge to the same answer and satisfies the energy balance to within one percent for high aspect ratios. In spite of the improvement of the computational model, lower aspect ratios still satisfy the energy balance less precisely. A comparison is made with an existing analytical theory by Waterman and Pedersen. This theory solves a more approximate form of the Pocklington equation. The solutions of this study agree with the analytical theory for very thin wires and give a small but significant amplitude and resonance shift for lower aspect ratios. All three solutions are in agreement with the numerous available experimental results to within the experimental errors. The measurements of this study were used to examine the agreement with recently developed theory for long wavelength fibrous aerosol attenuative properties (extinction and components absorption, scattering). This was intended to be the final phase of a long and systematic examination of the theory's key features. In this case the parameters were high conductivities coupled with a broad range of fiber diameters. It is clear that there is a limit on the extinction efficiency or effective extinction cross section per unit fiber volume represented by the fiber diameter of translucency, that is, the diameter at which the fiber is not completely opaque to the electromagnetic energy. This is approximated by the classical

  12. A simple and reliable implementation of all-fiber velocity interferometer

    Science.gov (United States)

    Tao, Tianjiong; Wang, Xiang; Weng, Jidong; Ma, Heli; Liu, Shenggang

    2016-12-01

    This work reports a fiber velocity interferometer (FVI), mainly used for velocity profile measurements of materials in dynamic compression experiments. This FVI generates two pairs of orthogonal signals with only one fiber-coupled optical hybrid to achieve push-pull analysis, which is traditionally obtained by a set of discrete optical components in a velocity interferometer system for any reflector (VISAR). These signals are received differentially by two balanced detectors. Common mode fluctuations of signals caused by rapid changes in light intensity are suppressed in this way, and the signals will not easily exceed the dynamic range of recorders anymore. Furthermore, a dual-core fiber probe is used to reduce disturbance from unwanted lights. At the Institute of Fluid Physics, FVI has been successfully applied in high-speed measurements up to several kilometers per second with almost the same precision of the heterodyne velocimetry (HV), which is now considered to be a reliable and accurate technique.

  13. Suppression of Fiber Modal Noise Induced Radial Velocity Errors for Bright Emission-Line Calibration Sources

    CERN Document Server

    Mahadevan, Suvrath; Ramsey, Lawrence; Venditti, Nick

    2014-01-01

    Modal noise in optical fibers imposes limits on the signal to noise and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity (RV) spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high signal to noise. Many of these spectrographs plan to use highly coherent emission line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial mass planets. These high precision calibration sources often use single mode fibers or highly coherent sources. Coupling light from single mode fibers to multi-mode fibers leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf (COTS) solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to...

  14. STUDIES ON PAN MACROMOLECULAR SEMICONDUCTING FIBER 1. PREPARATION OF PAN CONDUCTING FIBER TREATED BY STANNIC CHLORIDE AND ITS SEMICONDUCTING BEHAVIOUR

    Institute of Scientific and Technical Information of China (English)

    WANG Dexi; CUI Dayuan; LUO Boliang; WANG Xiugang; WU Renjie

    1984-01-01

    The PAN fiber treated by Lewis acid (e.g. stannic chloride) could be transformed into a macromolecular conducting fiber by further thermal treatment. Depending on thermal treatment condition the resistance of the fiber varied from 103 to 1012 Ω and kept stable after hydrolysis. The fiber has enough strength to be processed by various means. This is a new kind of macromolecular semiconducting fiber having some characteristics similar to those of organic semiconductors.

  15. Generation of pseudo-high-order group velocity locked vector solitons in fiber lasers

    CERN Document Server

    Jin, Xinxin; Li, Lei; Ge, Yanqi; Luo, Jiaolin; Zhang, Qian; Tang, Dingyuan; Shen, Deyuan; Fu, Songnian; Liu, Deming; Zhao, Luming

    2015-01-01

    We propose and experimentally demonstrate the generation of pseudo-high-order group velocity locked vector solitons (GVLVS) in a fiber laser using a SESAM as the mode locker. With the help of an external all-fiber polarization resolved system, a GVLVS with a two-humped pulse along one polarization while a single-humped pulse along the orthogonal polarization could be obtained. The phase difference between the two humps is 180 degree.

  16. Velocity, force, power, and Ca2+ sensitivity of fast and slow monkey skeletal muscle fibers

    Science.gov (United States)

    Fitts, R. H.; Bodine, S. C.; Romatowski, J. G.; Widrick, J. J.

    1998-01-01

    In this study, we determined the contractile properties of single chemically skinned fibers prepared from the medial gastrocnemius (MG) and soleus (Sol) muscles of adult male rhesus monkeys and assessed the effects of the spaceflight living facility known as the experiment support primate facility (ESOP). Muscle biopsies were obtained 4 wk before and immediately after an 18-day ESOP sit, and fiber type was determined by immunohistochemical techniques. The MG slow type I fiber was significantly smaller than the MG type II, Sol type I, and Sol type II fibers. The ESOP sit caused a significant reduction in the diameter of type I and type I/II (hybrid) fibers of Sol and MG type II and hybrid fibers but no shift in fiber type distribution. Single-fiber peak force (mN and kN/m2) was similar between fiber types and was not significantly different from values previously reported for other species. The ESOP sit significantly reduced the force (mN) of Sol type I and MG type II fibers. This decline was entirely explained by the atrophy of these fiber types because the force per cross-sectional area (kN/m2) was not altered. Peak power of Sol and MG fast type II fiber was 5 and 8.5 times that of slow type I fiber, respectively. The ESOP sit reduced peak power by 25 and 18% in Sol type I and MG type II fibers, respectively, and, for the former fiber type, shifted the force-pCa relationship to the right, increasing the Ca2+ activation threshold and the free Ca2+ concentration, eliciting half-maximal activation. The ESOP sit had no effect on the maximal shortening velocity (Vo) of any fiber type. Vo of the hybrid fibers was only slightly higher than that of slow type I fibers. This result supports the hypothesis that in hybrid fibers the slow myosin heavy chain would be expected to have a disproportionately greater influence on Vo.

  17. An efficient, compact, and versatile fiber double scrambler for high precision radial velocity instruments

    CERN Document Server

    Halverson, Samuel; Mahadevan, Suvrath; Ramsey, Lawrence; Levi, Eric; Schwab, Christian; Hearty, Fred; MacDonald, Nick

    2015-01-01

    We present the design and test results of a compact optical fiber double-scrambler for high-resolution Doppler radial velocity instruments. This device consists of a single optic: a high-index $n$$\\sim$2 ball lens that exchanges the near and far fields between two fibers. When used in conjunction with octagonal fibers, this device yields very high scrambling gains and greatly desensitizes the fiber output from any input illumination variations, thereby stabilizing the instrument profile of the spectrograph and improving the Doppler measurement precision. The system is also highly insensitive to input pupil variations, isolating the spectrograph from telescope illumination variations and seeing changes. By selecting the appropriate glass and lens diameter the highest efficiency is achieved when the fibers are practically in contact with the lens surface, greatly simplifying the alignment process when compared to classical double-scrambler systems. This prototype double-scrambler has demonstrated significant pe...

  18. Conduction velocity is regulated by sodium channel inactivation in unmyelinated axons innervating the rat cranial meninges.

    Science.gov (United States)

    De Col, Roberto; Messlinger, Karl; Carr, Richard W

    2008-02-15

    Axonal conduction velocity varies according to the level of preceding impulse activity. In unmyelinated axons this typically results in a slowing of conduction velocity and a parallel increase in threshold. It is currently held that Na(+)-K(+)-ATPase-dependent axonal hyperpolarization is responsible for this slowing but this has long been equivocal. We therefore examined conduction velocity changes during repetitive activation of single unmyelinated axons innervating the rat cranial meninges. In direct contradiction to the currently accepted postulate, Na(+)-K(+)-ATPase blockade actually enhanced activity-induced conduction velocity slowing, while the degree of velocity slowing was curtailed in the presence of lidocaine (10-300 microm) and carbamazepine (30-500 microm) but not tetrodotoxin (TTX, 10-80 nm). This suggests that a change in the number of available sodium channels is the most prominent factor responsible for activity-induced changes in conduction velocity in unmyelinated axons. At moderate stimulus frequencies, axonal conduction velocity is determined by an interaction between residual sodium channel inactivation following each impulse and the retrieval of channels from inactivation by a concomitant Na(+)-K(+)-ATPase-mediated hyperpolarization. Since the process is primarily dependent upon sodium channel availability, tracking conduction velocity provides a means of accessing relative changes in the excitability of nociceptive neurons.

  19. Effects of Ni catalyzer on growth velocity and morphology of SiC nano-fibers

    Institute of Scientific and Technical Information of China (English)

    XU Xian-feng; XIAO Peng; XIONG Xiang; HUANG Bai-yun

    2009-01-01

    Composite felts reinforced by both SiC nano-fibers (SiC-NFs) and carbon fibers were prepared at 1 273 K using Ni granules as catalyzers with different deposition time. SiC-NFs were deposited on the surface of the carbon fibers in situ by catalytic chemical vapor deposition(CCVD). The phase, microstructure and morphology of the fibers after electroplating and deposition were characterized by XRD, SEM and TEM. The results show that the SiC-NFs produced by CCVD are composed of single crystal of β-SiC. It is found that smaller nano-granules are more active as catalyzers. The resulting SiC-NFs appear more spindle-like and have a more homogeneous dispersion. The mass change of the samples before and after deposition shows that using more Ni granules results in a faster growth velocity of SiC-NFs. With the same electroplating time, the growth velocity of the SiC-NFs first increases and then decreases. At around 4 h, it reaches the maximum growth velocity, and it becomes nearly constant at around 8 h. After 8 h, the stable growth velocity of the electroplated Ni samples is faster than that of the conventional sample produced without catalyzers, because the SiC-NFs can improve the specific surface area and the activity of the surface.

  20. Functionalised hybrid materials of conducting polymers with individual wool fibers.

    Science.gov (United States)

    Kelly, Fern M; Johnston, James H; Borrmann, Thomas; Richardson, Michael J

    2008-04-01

    Composites of natural protein materials, such as merino wool, with the conducting polymers polypyrrole (PPy) and polyaniline (PAn) have been successfully synthesised. In doing so, hybrid materials have been produced in which the mechanical strength and flexibility of the fibers is retained whilst also incorporating the desired chemical and electrical properties of the polymer. Scanning electron microscopy shows PPy coatings to comprise individual polymer spheres, approximately 100 to 150 nm in diameter. The average size of the polymer spheres of PAn was observed to be approximately 50 to 100 nm in diameter. These spheres fuse together in a continuous sheet to coat the fibers in their entirety. The reduction of silver ions to silver metal nanoparticles onto the redox active polymer surface has also been successful and thus imparts anti-microbial properties to the hybrid materials. This gives rise to further applications requiring the inhibition of microbial growth. The chemical and physical characterisation of such products has been undertaken through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electrical conductivity, cyclic voltammetry, X-ray photoelectron spectroscopy (XPS) and the testing of their anti-microbial activity.

  1. Fiber-optic laser-Doppler anemometer microscope developed for the measurement of microvascular red cell velocity.

    Science.gov (United States)

    Seki, J

    1990-11-01

    A fiber-optic laser-Doppler anemometer microscope (FLDAM) was developed and its applicability to the study of microvascular blood flow was examined by measuring red cell velocities in vivo and in vitro. The FLDAM consists of an intravital microscope equipped with a fringe-mode back-scatter LDA. A data processing method of the Doppler signal which used frequency averaging over the entire frequency range of the power spectrum was developed. Spatial resolution of the FLDAM varied from 17 to 200 microns with 50X to 5X objectives. In vitro experiments showed that the red cell velocity obtained by the FLDAM was equal to the mean flow velocity, within the accuracy of the measurements, for tube diameters from 35 to 100 microns, mean velocity from 0.7 to 17 mm/sec, and feed hematocrit of 20%, when 10X or 20X objectives were used. In vivo red cell velocity measurements conducted with the FLDAM in microvessels of rat mesentery with diameters from 6.5 to 49 microns showed that red cell velocities were about 1/1.6 times smaller than those obtained by the two-slit technique, which also suggests that the velocity obtained by the FLDAM corresponds to the mean flow velocity. This relationship was also established from theoretical considerations for the case where the FLDAM sampling volume covers the entire vessel cross section. Furthermore the frequency response of the FLDAM was established to be about 20 Hz, which was sufficient for measurement of pulsatile velocities in rat mesenteric microvessels.

  2. Group velocity locked vector dissipative solitons in a high repetition rate fiber laser

    CERN Document Server

    Luo, Yiyang; Li, Lei; Sun, Qizhen; Wu, Zhichao; Xu, Zhilin; Fu, Songnian; Zhao, Luming

    2016-01-01

    Vectorial nature of dissipative solitons (DSs) with high repetition rates is studied for the first time in a normal-dispersion fiber laser. Despite the fact that the formed DSs are strongly chirped and the repetition rate is greater than 100 MHz, polarization locked and polarization rotating group velocity locked vector DSs can be formed under 129.3 MHz fundamental mode-locking and 258.6 MHz harmonic mode-locking of the fiber laser, respectively. The two orthogonally polarized components of these vector DSs possess distinctly different central wavelengths and travel together at the same group velocity in the laser cavity, resulting in a gradual spectral edge and small steps on the optical spectra, which can be considered as an auxiliary indicator of the group velocity locked vector DSs.

  3. Fetal atrioventricular and outflow tract flow velocity waveforms during conducted and blocked supraventricular extrasystoles

    NARCIS (Netherlands)

    K. van der Mooren (K.); J.W. Wladimiroff (Juriy); Th. Stijnen (Theo)

    1992-01-01

    textabstractMaximum flow velocity waveforms at atrioventricular and outflow tract level were studied cross‐sectionally in 19 human fetuses with conducted and/or blocked supraventricular extrasystoles ranging from 25 to 38 weeks of gestation. At outflow tract level, peak systolic velocity and acceler

  4. The group velocity variation of Lamb wave in fiber reinforced composite plate.

    Science.gov (United States)

    Rhee, Sang-Ho; Lee, Jeong-Ki; Lee, Jung-Ju

    2007-12-01

    Experimentally measured Lamb wave group velocities in composite materials with anisotropic characteristics are not the same as the theoretical group velocities which is calculated with the Lamb wave dispersion equation. This discrepancy arises from the fact that the angle between the group velocity direction and the phase velocity direction in anisotropic materials exists. Wave propagation in a composite material with anisotropic characteristics should be considered with respect to magnitude correction in addition to direction correction. In this study, S0 mode phase velocity dispersion curves are depicted with the variation of degree with respect to the fiber direction using a Lamb wave dispersion relation in the unidirectional, bidirectional, and quasi-isotropic composite plates. Slowness surface is sketched by the reciprocal value of the phase velocity curves. The magnitude and direction of the group velocity could be calculated from the slowness surface. The recalculated group velocities with consideration of the magnitude and direction from the slowness surface are compared with experimentally measured group velocities. The proposed method shows good agreements with theoretical and experimental results.

  5. Intrinsically Conductive Polymer Fibers from Thermoplastic trans-1,4-Polyisoprene.

    Science.gov (United States)

    Han, Peng; Zhang, Xiaohong; Qiao, Jinliang

    2016-05-17

    Herein, we report a new strategy to prepare conductive polymer fibers to overcome the insurmountable weakness of current conductive polymer fibers. First, special thermoplastic polymers are processed into polymer fibers using a conventional melt-spinning process, and then the nonconductive polymer fibers are converted into intrinsically conductive polymer fibers. Using this new strategy, intrinsically conductive polymer fibers have been prepared by melt spinning low-cost thermoplastic trans-1,4-polyisoprene and doping with iodine, which can be as fine as 0.01 mm, and the resistivity can be as low as 10(-2) Ω m. Moreover, it has been found that drawing can improve the orientation of trans-1,4-polyisoprene crystals in the fibers and, thus, the conductivity of the conductive polymer fibers. Therefore, conductive fibers with excellent conductivities can be prepared by large drawing ratios before doping. Such conductive polymer fibers with low cost could be used in textile, clothing, packing, and other fields, which would benefit both industry and daily life. The newly developed method also allows one to produce conductive polymers of any shape besides fibers for antistatic or conductive applications.

  6. Suppression of Fiber Modal Noise Induced Radial Velocity Errors for Bright Emission-line Calibration Sources

    Science.gov (United States)

    Mahadevan, Suvrath; Halverson, Samuel; Ramsey, Lawrence; Venditti, Nick

    2014-05-01

    Modal noise in optical fibers imposes limits on the signal-to-noise ratio (S/N) and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high S/N. Many of these spectrographs plan to use highly coherent emission-line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial-mass planets. These high-precision calibration sources often use single-mode fibers or highly coherent sources. Coupling light from single-mode fibers to multi-mode fibers leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to spectrograph calibration systems. Our solution uses an integrating sphere in conjunction with a diffuser that is moved rapidly using electrostrictive polymers, and is generally superior to most tested forms of mechanical fiber agitation. We demonstrate a high level of modal noise reduction with a narrow bandwidth 1550 nm laser. Our relatively inexpensive solution immediately enables spectrographs to take advantage of the innate precision of bright state-of-the art calibration sources by removing a major source of systematic noise.

  7. Measurement of group-velocity dispersion of Bloch modes in photonic-crystal-fiber rocking filters.

    Science.gov (United States)

    Wong, G K L; Zang, L; Kang, M S; Russell, P St J

    2010-12-01

    We use low-coherence interferometry to measure the group-velocity dispersion (GVD) of the fast and slow Bloch modes of structural rocking filters, produced by twisting a highly birefringent photonic crystal fiber to and fro while scanning a focused CO(2) laser beam along it. The GVD curves in the vicinity of the resonant wavelength differ dramatically from those of the unperturbed fiber, suggesting that rocking filters could be used in the optimization of, e.g., four-wave mixing and supercontinuum generation. Excellent agreement is obtained between theory and experiment.

  8. Highly spatially resolved velocity measurements of a turbulent channel flow by a fiber-optic heterodyne laser-Doppler velocity-profile sensor

    Energy Technology Data Exchange (ETDEWEB)

    Shirai, K.; Pfister, T.; Buettner, L.; Czarske, J. [Dresden University of Technology (TU Dresden), Department of Electrical Engineering and Information Technology, Chair for Measurement and Testing Techniques, Dresden (Germany); Mueller, H. [Physikalisch-Technische Bundesanstalt Braunschweig (PTB), Department 1.4 Gas Flow, Braunschweig (Germany); Becker, S.; Lienhart, H.; Durst, F. [Institute of Fluid Mechanics (LSTM), Friedrich-Alexander-University Erlangen-Nuernberg, Erlangen (Germany)

    2006-03-15

    Velocity measurements with a high spatial resolution are important in turbulent flow research. In this paper, we report on the development of a new fiber-optic laser-Doppler velocity-profile sensor exhibiting a spatial resolution of up to 5 {mu}m and its application to turbulent boundary layers. The sensor developed in the present work employs a frequency-division-multiplexing technique in order to separate two measurement signals from the two fringe systems. Velocity measurements close to zero at the solid wall were realized using heterodyne technique. The use of fiber optics improved a robustness of the sensor. The measurement accuracy of the sensor was experimentally investigated with respect to the spatial resolution and velocity. Universal velocity profile of a turbulent flow was obtained in a fully developed channel flow. Mean and fluctuating velocity are presented with a high spatial resolution. (orig.)

  9. Conduction velocity of the human spinothalamic tract as assessed by laser evoked potentials

    DEFF Research Database (Denmark)

    Cruccu, G.; Iannetti, G. D.; Agostino, R.

    2000-01-01

    To study the conduction velocity of the spinothalamic tract (STT) we delivered CO2 laser pulses, evoking pinprick sensations, to the skin overlying the vertebral spinous processes at different spinal levels from C5 to T10 and recorded evoked potentials (LEPs) in 15 healthy human subjects. These s......To study the conduction velocity of the spinothalamic tract (STT) we delivered CO2 laser pulses, evoking pinprick sensations, to the skin overlying the vertebral spinous processes at different spinal levels from C5 to T10 and recorded evoked potentials (LEPs) in 15 healthy human subjects....... These stimuli yielded large-amplitude vertex potentials consisting of a negative wave at a peak latency of about 200 ms followed by a positive wave at a peak latency of about 300 ms. The mean conduction velocity of the STT was 21 m/s, i.e. higher than the reported velocity of the corresponding primary sensory...

  10. Second-harmonic generation with zero group-velocity mismatch in nonlinear photonic crystal fibers

    DEFF Research Database (Denmark)

    Bache, Morten; Lægsgaard, Jesper; Bang, Ole;

    2006-01-01

    We consider an index-guiding silica photonic crystal fiber with a triangular hole-pattern and a periodically poled quadratic nonlinearity. By tuning the pitch and the relative size of the holes, second-harmonic generation with zero group-velocity mismatch is found to be feasible for any fundamental...... wavelength above 780 nm. The phase-velocity mismatch has a lower limit with coherence lengths in the micron range. The nonlinear strength is optimized when the fundamental has maximum confinement in the core. The conversion bandwidth allows for fs-pulse conversion and 4-180%/(Wmiddotcm2) relative...

  11. Zero-velocity solitons in high-index photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2011-01-01

    -light modes in a solid core chalcogenide PCF are used to parameterize the model, which is shown to support standing and moving spatial solitons. Inclusion of Raman scattering slows down moving solitons exponentially, so that the zero-velocity soliton becomes an attractor state. An analytical expression......Nonlinear propagation in slow-light states of high-index photonic crystal fibers (PCFs) is studied numerically. To avoid divergencies in dispersion and nonlinear parameters around the zero-velocity mode, a time-propagating generalized nonlinear Schrödinger equation is formulated. Calculated slow...

  12. Tuning quadratic nonlinear photonic crystal fibers for zero group-velocity mismatch

    DEFF Research Database (Denmark)

    Bache, Morten; Nielsen, Hanne; Lægsgaard, Jesper;

    2006-01-01

    We consider an index-guiding silica photonic crystal fiber with a triangular hole pattern and a periodically poled quadratic nonlinearity. By tuning the pitch and the relative hole size, second-harmonic generation with zero group-velocity mismatch is found for any fundamental wavelength above 780...... nm. The nonlinear strength is optimized when the fundamental has maximum confinement in the core. The conversion bandwidth allows for femtosecond-pulse conversion, and 4%-180% W-1 cm-2 relative efficiencies were found. © 2006 Optical Society of America......We consider an index-guiding silica photonic crystal fiber with a triangular hole pattern and a periodically poled quadratic nonlinearity. By tuning the pitch and the relative hole size, second-harmonic generation with zero group-velocity mismatch is found for any fundamental wavelength above 780...

  13. The real role of forearm mixed nerve conduction velocity in the assessment of proximal forearm conduction slowing in carpal tunnel syndrome.

    Science.gov (United States)

    Chang, Ming-Hong; Lee, Yee-Chung; Hsieh, Peiyuan F

    2008-12-01

    The decrease of forearm median motor conduction velocity (CV) in carpal tunnel syndrome (CTS) is a common electrodiagnostic finding in clinical practice and is possibly secondary to either conduction block at wrist or retrograde conduction slowing (RCS). This study is attempted to confirm the existence of RCS and to explore why this controversy occurs for a long time. Eighty CTS patients and controls were recruited. In addition to conventional electrodiagnosis, subjects received further electrodiagnostic protocol. First, a recording electrode was placed over the wrist and then at elbow with palm stimulation to calculate indirect forearm mixed nerve CV (forearm-mix CV) that represented real measurement of nerve fibers through the carpal tunnel. Then, direct measurement of forearm-mix CV was performed with recording at the elbow and stimulation at the wrist. CTS patients had markedly prolonged distal motor and sensory latencies and significantly prolonged wrist-palm sensory and motor conduction. There was a significant decrease in forearm median motor CV; however, there was no difference in ulnar distal motor latency and forearm motor CV. The mild decrease of forearm median motor CV was not proportional to the marked reduction of W-P MCV and there was no demonstrated conduction block at wrist, implying the reduction of forearm median motor CV is unlikely due to conduction blockage or slowing of the large myelinating fibers at the wrist and RCS really occurs over the forearm median nerve. In addition, the direct Forearm-mix CV was similar in CTS and controls; however, there was a significant decrease in indirect forearm-mix CV only in the CTS. Moreover, the difference between direct and indirect forearm-mix CV was significantly greater and poor consistency of direct and indirect forearm-mix CV in CTS, suggesting that direct and indirect forearm-mix CV represent CV from quite different nerve fibers. Therefore, we conclude that RCS really does occur in CTS and the

  14. Blood pulse wave velocity and pressure sensing via fiber based and free space based optical sensors

    Science.gov (United States)

    Sirkis, Talia; Beiderman, Yevgeny; Agdarov, Sergey; Beiderman, Yafim; Zalevsky, Zeev

    2017-02-01

    Continuous noninvasive measurement of vital bio-signs, such as cardiopulmonary parameters, is an important tool in evaluation of the patient's physiological condition and health monitoring. On the demand of new enabling technologies, some works have been done in continuous monitoring of blood pressure and pulse wave velocity. In this paper, we introduce two techniques for non-contact sensing of vital bio signs. In the first approach the optical sensor is based on single mode in-fibers Mach-Zehnder interferometer (MZI) to detect heartbeat, respiration and pulse wave velocity (PWV). The introduced interferometer is based on a new implanted scheme. It replaces the conventional MZI realized by inserting of discontinuities in the fiber to break the total internal reflection and scatter/collect light. The proposed fiber sensor was successfully incorporated into shirt to produce smart clothing. The measurements obtained from the smart clothing could be obtained in comfortable manner and there is no need to have an initial calibration or a direct contact between the sensor and the skin of the tested individual. In the second concept we show a remote noncontact blood pulse wave velocity and pressure measurement based on tracking the temporal changes of reflected secondary speckle patterns produced in human skin when illuminated by a laser beams. In both concept experimental validation of the proposed schemes is shown and analyzed.

  15. Conductive polymer combined silk fiber bundle for bioelectrical signal recording.

    Directory of Open Access Journals (Sweden)

    Shingo Tsukada

    Full Text Available Electrode materials for recording biomedical signals, such as electrocardiography (ECG, electroencephalography (EEG and evoked potentials data, are expected to be soft, hydrophilic and electroconductive to minimize the stress imposed on living tissue, especially during long-term monitoring. We have developed and characterized string-shaped electrodes made from conductive polymer with silk fiber bundles (thread, which offer a new biocompatible stress free interface with living tissue in both wet and dry conditions.An electroconductive polyelectrolyte, poly(3,4-ethylenedioxythiophene-poly(styrenesulfonate (PEDOT-PSS was electrochemically combined with silk thread made from natural Bombyx mori. The polymer composite 280 µm thread exhibited a conductivity of 0.00117 S/cm (which corresponds to a DC resistance of 2.62 Mohm/cm. The addition of glycerol to the PEDOT-PSS silk thread improved the conductivity to 0.102 S/cm (20.6 kohm/cm. The wettability of PEDOT-PSS was controlled with glycerol, which improved its durability in water and washing cycles. The glycerol treated PEDOT-PSS silk thread showed a tensile strength of 1000 cN in both wet and dry states. Without using any electrolytes, pastes or solutions, the thread directly collects electrical signals from living tissue and transmits them through metal cables. ECG, EEG, and sensory evoked potential (SEP signals were recorded from experimental animals by using this thread placed on the skin. PEDOT-PSS silk glycerol composite thread offers a new class of biocompatible electrodes in the field of biomedical and health promotion that does not induce stress in the subjects.

  16. Dependency of the force-velocity relationships on Mg ATP in different types of muscle fibers from Xenopus laevis.

    OpenAIRE

    Stienen, G J; Laarse, W. J. van der; Elzinga, G.

    1988-01-01

    MgATP binding to the actomyosin complex is followed by the dissociation of actin and myosin. The rate of this dissociation process was determined from the relationship between the maximum velocity of shortening and the MgATP concentration. It is shown here that the overall dissociation rate is rather similar in different types of muscle fibers. The relation between MgATP concentration and the maximum shortening velocity was investigated in fast and slow fibers and bundles of myofibrils of the...

  17. The Effect of Temperature and Nanoclay on the Low Velocity and Ballistic Behavior of Woven Glass-Fiber Reinforced Composites

    Science.gov (United States)

    Patrin, Lauren

    The objective of this research was to study the effect of nanoclay and temperature on the behavior of woven glass-fabric reinforced epoxy composite under low velocity and ballistic impacts. The materials used in manufacturing the composite were S2 (6181) glass-fibers, epoxy resin (EPON 828), hardener (Epikure 3230), nanoclay and Heloxy 61 modifier. The nanoclay addition was 0%, 1%, 3% and 5% by weight, with respect to the resin. All specimens were manufactured at the City College facilities using vacuum infusion. Tensile tests were conducted to characterize the material and obtain the Young's modulus, ultimate stress, failure strain, Poisson's ratio, shear modulus and shear strength and their variation with nanoclay percentage and temperature. The tests were conducted at room temperature (21°C/70°F), -54°C (-65°F), -20°C (-4°F), 49°C (120°F) and 71°C (160°F). Next composite specimens with 0%, 1%, 3% and 5% nanoclay by weight, with respect to the resin, were subjected to low velocity impact at the previously specified temperatures to determine dynamic force, displacement and energy correlations. The extent of damage was studied using the ultrasound technique. Then ballistic tests were conducted on the nanoclay infused specimens at room temperature to obtain the ballistic limit (V50) and the damage behavior of the composite. The dynamic finite element analysis (FEA) software LS-DYNA was used to model and simulate the results of low velocity impact tests. Good agreement was obtained between experimental and numerical (FEA) results. Analytical analyses were undertaken to compare the results from the tensile experiments. The finite element analysis (FEA) allowed for further analytical comparison of the results. The FEA platform used was LS-DYNA due to its proficient dynamic and damage capabilities in composite materials. The FEA was used to model and simulate the low velocity impacts and compare the results to experiments.

  18. Numerical Investigation of Characteristic of Anisotropic Thermal Conductivity of Natural Fiber Bundle with Numbered Lumens

    Directory of Open Access Journals (Sweden)

    Guan-Yu Zheng

    2014-01-01

    Full Text Available Natural fiber bundle like hemp fiber bundle usually includes many small lumens embedded in solid region; thus, it can present lower thermal conduction than that of conventional fibers. In the paper, characteristic of anisotropic transverse thermal conductivity of unidirectional natural hemp fiber bundle was numerically studied to determine the dependence of overall thermal property of the fiber bundle on that of the solid region phase. In order to efficiently predict its thermal property, the fiber bundle was embedded into an imaginary matrix to form a unit composite cell consisting of the matrix and the fiber bundle. Equally, another unit composite cell including an equivalent solid fiber was established to present the homogenization of the fiber bundle. Next, finite element thermal analysis implemented by ABAQUS was conducted in the two established composite cells by applying proper thermal boundary conditions along the boundary of unit cell, and influences of the solid region phase and the equivalent solid fiber on the composites were investigated, respectively. Subsequently, an optional relationship of thermal conductivities of the natural fiber bundle and the solid region was obtained by curve fitting technique. Finally, numerical results from the obtained fitted curves were compared with the analytic Hasselman-Johnson’s results and others to verify the present numerical model.

  19. Ionic drift velocity measurement on hot-pressed Ag+ ion conducting glass-polymer electrolytes

    Indian Academy of Sciences (India)

    Angesh Chandra

    2015-12-01

    Ionic drift velocity (d) measurements of a new Ag+ ion conducting glass-polymer electrolytes (GPEs): (1−x) PEO : x[0.8(0.75AgI:0.25AgCl) : 0.2(Ag2 O:V2O5)], where 0 < x < 50 wt%, were reported. GPEs were casted using the hot-press techniques developed in recent times. The composition: 70PEO : 30[0.8(0.75AgI : 0.25AgCl) : 0.2(Ag2O : V2O5)] with conductivity ()∼ 7.7 × 10−7 S cm−1 was identified as highest conducting composition from the compositional-dependent conductivity studies. The ionic mobility (), mobile ion concentration (), ionic transference number (ion) and ionic drift velocity (d) of GPEs were determined at different temperatures with the help of the d.c. polarization technique and other well-known important relations.

  20. Velocity measurements of low Reynolds number tube flow using fiber-optic technology

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, J.C.

    1993-03-01

    In 1988 Nielsen started work to measure the spatial variability of the mass flux vector being transported in a porous medium. To measure the spatial variability of the mass flux vector, the spatial variability of its components(velocity, concentration) must be measured. Nielsen was successful in measuring the pore level concentration at many different pores and in verifying the assumption that a nonuniform concentration field exists within the mixing zone between two miscible fluids. However, Nielsen was unable to conduct the necessary pore level velocity measurements needed. Nielsen's work is being continued and a probe is being developed that will measure both velocity and concentration components at pore level. The probe is essentially the same probe used to make the pore level concentration measurements with added capabilities needed to make the velocity measurements. This probe has several design variables, dealing primarily with the velocity component, that need further investigation. The research presented in this thesis investigates these parameters by performing experiments in a capillary tube. The tube is a controlled system where the velocity of the fluid can be determined from the volumetric flow rate using Poiseuille's solution for viscous flow. Also, a statistically based relationship between the velocity measured with the probe and the velocity determined from the volumetric flow rate has been developed.

  1. Velocity measurements of low Reynolds number tube flow using fiber-optic technology

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, J. Christopher [Univ. of Vermont, Burlington, VT (United States)

    1993-03-01

    In 1988 Nielsen started work to measure the spatial variability of the mass flux vector being transported in a porous medium. To measure the spatial variability of the mass flux vector, the spatial variability of its components(velocity, concentration) must be measured. Nielsen was successful in measuring the pore level concentration at many different pores and in verifying the assumption that a nonuniform concentration field exists within the mixing zone between two miscible fluids. However, Nielsen was unable to conduct the necessary pore level velocity measurements needed. Nielsen`s work is being continued and a probe is being developed that will measure both velocity and concentration components at pore level. The probe is essentially the same probe used to make the pore level concentration measurements with added capabilities needed to make the velocity measurements. This probe has several design variables, dealing primarily with the velocity component, that need further investigation. The research presented in this thesis investigates these parameters by performing experiments in a capillary tube. The tube is a controlled system where the velocity of the fluid can be determined from the volumetric flow rate using Poiseuille`s solution for viscous flow. Also, a statistically based relationship between the velocity measured with the probe and the velocity determined from the volumetric flow rate has been developed.

  2. Comparison of Nerve Excitability Testing, Nerve Conduction Velocity, and Behavioral Observations for Acrylamide Induced Peripheral Neuropathy

    Science.gov (United States)

    Nerve excitability (NE) testing is a sensitive method to test for peripheral neurotoxicity in humans,and may be more sensitive than compound nerve action potential (CNAP) or nerve conduction velocity (NCV).We used acrylamide to compare the NE and CNAP/NCV methods. Behavioral test...

  3. Comparison of Nerve Excitability Testing, Nerve Conduction Velocity, and Behavioral Observations for Acrylamide Induced Peripheral Neuropathy

    Science.gov (United States)

    Nerve excitability (NE) testing is a sensitive method to test for peripheral neurotoxicity in humans,and may be more sensitive than compound nerve action potential (CNAP) or nerve conduction velocity (NCV).We used acrylamide to compare the NE and CNAP/NCV methods. Behavioral test...

  4. The Effects of Force and Joint Angle on Muscle Conduction Velocity Estimation

    Science.gov (United States)

    2007-11-02

    Institute of Biomedical Engineering, University of New Brunswick Abstract - Conduction velocity estimated from the surface myoelectric signal has been...changes in joint angle and/or muscle force. Results from this study using myoelectric signals collected from the biceps brachii, indicate that conduction... myoelectric signal (MES) to track changes in muscle biochemistry which are caused by fatigue. By estimating the power spectrum of the surface MES during

  5. Intercalation of Carbon Nanotube Fibers to Improve their Conductivity Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposed research will explore how NASA intercalation technology can be used to lower the resistivity of the new Rice-Teijin fiber make them viable for NASA...

  6. Conductivity and Ambient Stability of Halogen-Doped Carbon Nanotube Fibers

    Science.gov (United States)

    Gaier, J. R.; Chirino, C. M.; Chen, M.; Waters, D. L.; Tran, Mai Kim; Headrick, R.; Young, C. C.; Tsentalovich, D.; Whiting, B.; Pasquali, M.; Waarbeek, Ron ter; Otto, Marcin J.

    2014-01-01

    Carbon nanotube fibers were fabricated using a variety of spinning conditions and post-spinning processing with the goal of creating a high-conductivity yet environmentally stable fiber. These fiber variants were then doped with bromine, iodine, iodine chloride, or iodine bromide and their electrical and microstructural properties were characterized. Environmentally stable compounds were synthesized with electrical conductivity greater than 50,000 Scm.

  7. Measurement of bubble velocity using Capacitively Coupled Contactless Conductivity Detection (C4D) technique

    Institute of Scientific and Technical Information of China (English)

    Baoliang Wang; Ying Zhou; Haifeng Ji; Zhiyao Huang; Haiqing Li

    2013-01-01

    The feasibility of applying Capacitively Coupled Contactless Conductivity Detection (C4D) technique to measurement of bubble velocity in gas-liquid two-phase flow in millimeter-scale pipe is investigated.And,a new method,which combines the C4D technique and the principle of cross-correlation velocity measurement,is proposed for the measurement of bubble velocity.This research includes two parts.First,based on the principle of C4D,a new five-electrode C4D sensor is developed.Then,with two conductivity signals obtained by the C4D sensor,the velocity measurement of bubble is implemented according to the principle of cross-correlation.The research results indicate that the C4D technique is highly effective and anticipates a broad potential in the field of two-phase flow.Experimental results show that the fiveelectrode C4D sensor is suitable for measuring the velocity of single bubbles with a relative error of less than 5%.

  8. Toward accurate radial velocities with the fiber-fed GIRAFFE multi-object VLT spectrograph

    Science.gov (United States)

    Royer, Frederic; Blecha, Andre; North, Pierre; Simond, Gilles; Baratchart, Sebastien; Cayatte, Veronique; Chemin, Laurent; Palsa, Ralf

    2002-12-01

    We describe briefly the Data-Reduction of the VLT fiber-fed multi-object GIRAFFE spectrograph - part of the VLT FLAMES facility. We focus on specific features of GIRAFFE - the simultaneous wavelength calibration - and their impact on the data-reduction strategy. We describe the implementation of the global physical model and we compare the results obtained with the simulated, laboratory and preliminary data. We discuss the influence of critical parameters, the overall accuracy of the wavelength solution, and the stability and the robustness of the global model approach. We address the accuracy of radial velocity measurements illustrated by solar spectra obtained during the Preliminary Acceptance in Europe.

  9. Development of fiber optic laser Doppler velocimeter for measurement of local blood velocity

    Science.gov (United States)

    Ohba, Kenkich; Fujiwara, Noboru

    1993-08-01

    In order to measure the local velocity field in opaque fluid flows like blood flow, a new laser Doppler velocimeter having a pickup consisting of a small distributed index lens attached to the tips of two fibers which are joined side by side in parallel has been newly developed. The distributed index lens is the shape of a truncated cone. The flow field around this sensor has been measured very precisely by means of an ordinary LDV. The effect of turbidity of fluid on the quality of the laser Doppler signal from this sensor has been examined by experiments. As a result, it has been shown that this LDV sensor has a high signal-to-noise ratio, and that the disturbance against flow by the sensor is very small, and it is very promising as a velocity sensor for opaque or semi-opaque fluid flow like blood flow.

  10. Alteration of proximal conduction velocity at distal nerve injury in carpal tunnel syndrome: demyelinating versus axonal change.

    Science.gov (United States)

    Chang, Ming-Hong; Liu, Lu-Han; Lee, Yi-Chung; Hsieh, Peiyuan F

    2008-06-01

    The objective of this study was to determine the cause of median forearm motor conduction velocity (FMCV) slowing in patients with carpal tunnel syndrome, due to either focal conduction abnormality over wrist or retrograde conduction slowing, and to decide whether the slowing is related to severity of compression or not. Fifty carpal tunnel syndrome patients confirmed by conventional nerve conduction study with abnormal electromyography of the abductor pollicis brevis muscle were group 1, and 100 with normal electromyography, group 2. One hundred volunteers served as controls. In addition to conventional nerve conduction study of median and ulnar nerves, palmar stimulations for median mixed and motor nerves were also performed to calculate wrist-palm mixed nerve conduction time and motor conduction velocity (W-P MCV). For group 1, group 2, and control subjects, respectively, W-P MCV were 19.73+/-7.65 (mean+/-SD), 32.7+/-6.83, and 52.75+/-6.4 m/s, whereas median FMCV were 48.63+/-8.32, 54.42+/-2.11, and 57.86+/-4.24 m/s. There was a significant reduction in the W-P MCV (62.6%, Pulnar FMCV and sensory nerve conduction study results did not, suggesting the reduction of median W-P MCV is not parallel with that of median FMCV in both patients groups. Furthermore, there is a poor correlation of median FMCV and W-P MCV in patient groups, implying conduction blockage of the large myelinating fibers at the wrist, leaving only slower axons to be measured, is not the likely cause of reduction of FMCV. In addition, the reduction of compound muscle action potential amplitude of abductor pollicis brevis muscle, conduction block at wrist and weak correlation of median FMCV and compound muscle action potential amplitude of abductor pollicis brevis exclusively occurred in group 1. Therefore, the retrograde conduction slowing really occurs among patients with carpal tunnel syndrome-markedly in those with abnormal electromyography and mildly in those with only demyelination. This

  11. Electrical conductivity and velocity of highly ionized plasma flows - Theory and experiment.

    Science.gov (United States)

    Vendell, E. W.; Park, C.; Posch, R. E.

    1972-01-01

    Use of an immersible, three-coil, magnetic-induction probe, previously tested in a low-density supersonic argon jet, to measure electrical conductivity and velocity profiles of a highly ionized high-density nitrogen jet in the continuum flow regime where effects due to probe bow shocks and boundary layers might not be negligible. Measured centerline values of electrical conductivity and velocity were compared with predictions based on a theoretical analysis previously developed to study the gas as it expanded adiabatically and inviscidly from an equilibrium sonic state to the nozzle exit. The resulting numerical exit plane values for electron density and electron temperature were then substituted into the Spitzer-Haerm conductivity formula to compute a theoretical conductivity which agreed within 40% of the measured conductivity, while the calculated and experimental velocity values differed by as much as 50%. The lack of agreement was attributed to the possible use of invalid assumptions and boundary conditions in the computer analysis or to the unknown effects of shocks on the probe data.

  12. Modified carbon fibers to improve composite properties. [sizing fibers for reduced electrical conductivity and adhesion during combustion

    Science.gov (United States)

    Shepler, R. E.

    1979-01-01

    Thin coatings, 5 to 10 wt. percent, were applied to PAN-based carbon fibers. These coatings were intended to make the carbon fibers less electrically conductive or to cause fibers to stick together when a carbon fiber/epoxy composite burned. The effectiveness of the coatings in these regards was evaluated in burn tests with a test rig designed to simulate burning, impact and wind conditions which might release carbon fibers. The effect of the coatings on fiber and composite properties and handling was also investigated. Attempts at sizing carbon fibers with silicon dioxide, silicon carbide and boron nitride meet with varying degrees of success; however, none of these materials provided an electrically nonconductive coating. Coatings intended to stick carbon fibers together after a composite burned were sodium silicate, silica gel, ethyl silicate, boric acid and ammonium borate. Of these, only the sodium silicate and silica gel provided any sticking together of fibers. The amount of sticking was insufficient to achieve the desired objectives.

  13. Saltatory conduction in unmyelinated axons: Clustering of Na+ channels on lipid rafts allows micro-saltatory conduction in C-fibers

    Directory of Open Access Journals (Sweden)

    Ali eNeishabouri

    2014-10-01

    Full Text Available The action potential (AP, the fundamental signal of the nervous system, is carried by two types of axons: unmyelinated and myelinated fibers. In the former the action potential propagates continuously along the axon as established in large-diameter fibers. In the latter axons the AP jumps along the Nodes of Ranvier – discrete, anatomically specialized regions which contain very high densities of sodium ion (Na + channels. Therefore saltatory conduction is thought as the hallmark of myelinated axons, which enables faster and more reliable propagation of signals than in unmyelinated axons of same outer diameter.Recent molecular anatomy showed that in C-fibers, the very thin (0.1 μm diameter axons of the peripheral nervous system, Nav1.8 channels are clustered together on lipid rafts that float in the cell membrane. This localized concentration of Na+ channels resembles in structure the ion channel organization at the Nodes of Ranvier, yet it is currently unknown whether this translates into equivalent phenomenon of saltatory conduction or related-functional benefits and efficiencies. Therefore, we modeled biophysically realistic unmyelinated axons with both conventional and lipid-raft based organization of Na+ channels. We find that action potentials are reliably conducted in a micro-saltatory fashion along lipid rafts.Comparing APs in unmyelinated fibers with and without lipid rafts did not reveal any significant difference in either the metabolic cost or AP propagation velocity. By investigating the efficiency of AP propagation over Nav1.8 channels, we find however that the specific inactivation properties of these channels significantly increase the metabolic cost of signaling in C-fibers.

  14. Measurement Using Conductive Polymeric Fibers in a Wearable Sensor Platform

    Directory of Open Access Journals (Sweden)

    Ram Manoj Sarda

    2010-12-01

    Full Text Available The purpose of this study is to design polymer fiber sensors which can be embedded into a t-shirt for electrocardiography. Recent inventors have envisioned this concept, but the feasibility of this idea needs to be investigated. The sensors used in this study are designed in way to make good contact with the skin without using gel or any other adhesives which can cause pain when removed and can annoy the user. The method of using polymer fiber sensors in a fabric for the purpose of electrocardiogram (ECG signal detection was determined to be more feasible than the conventional silver/silver-chloride adhesive electrodes. This method of using polymer fibers as sensors for Electrocardiography is a novel method for this application.

  15. Braking of a magnetic dipole moving with an arbitrary velocity through a conducting pipe

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, B A; Kotel' nikov, Igor A [G.I. Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Tyutin, A A; Cherkasskii, Valerii S [Department of Physics, Novosibirsk State University, Novosibirsk (Russian Federation)

    2006-09-30

    Lectures introducing students to electromagnetic induction phenomena often feature the popular experiment in which a small magnet falling down a long conducting pipe is markedly decelerated by the retarding force due to Foucault eddy currents arising in the pipe. In this paper, a formula for the retarding force, valid both for low velocities (when the force is proportional to the velocity v of magnet motion) and high velocities (when it first decreases as v{sup -1} and then as v{sup -1/2}), is derived. The last two regimes are analogous to the collisionless (and hence unbounded) acceleration of plasma electrons and have not been previously described in the literature. The calculation of the retarding force in the presence of a longitudinal cut in the pipe wall is carried out, and experiments to measure this force are discussed. (methodological notes)

  16. Multi-channel laser Doppler velocimetry using a two-dimensional optical fiber array for obtaining instantaneous velocity distribution characteristics

    Science.gov (United States)

    Kyoden, Tomoaki; Yasue, Youichi; Ishida, Hiroki; Akiguchi, Shunsuke; Andoh, Tsugunobu; Takada, Yogo; Teranishi, Tsunenobu; Hachiga, Tadashi

    2015-01-01

    A laser Doppler velocimeter (LDV) has been developed that is capable of performing two-dimensional (2D) cross-sectional measurements. It employs two horizontal laser light sheets that intersect at an angle of 13.3°. Since the intersection region is thin, it can be used to approximately determine the 2D flow field. An 8 × 8 array of optical fibers is used to simultaneously measure Doppler frequencies at 64 points. Experiments were conducted to assess the performance of the LDV, and it was found to be capable of obtaining spatial and temporal velocity information at multiple points in a flow field. The technique is fast, noninvasive, and accurate over long sampling periods. Furthermore, its applicability to an actual flow field was confirmed by measuring the temporal velocity distribution of a pulsatile flow in a rectangular flow channel with an obstruction. The proposed device is thus a useful, compact optical instrument for conducting simultaneous 2D cross-sectional multipoint measurements.

  17. Composite materials of glycerol polyesters and piassava fibers as conducting membranes for PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Alves, J.L.; Jose, N.M.; Boaventura, J.S. [Federal Univ. of Bahia, Salvador (Brazil). Dept. of Physical Chemistry

    2009-07-01

    This paper described a method of using piassava fibers to produce polymers for proton exchange membrane fuel cells (PEMFCs). The composite membranes were produced using polyesters obtained from adipic and phthalic acid reactions with glycerol and piassava fibers treated with phosphoric acid. The piassava and polyesters were prepared as a mixture in liquid nitrogen. The mixture was then hot-pressed in order to produce composites with a fiber mass of 3, 5, 10 and 15 per cent. The fibers were then analyzed using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The analyses demonstrated that the piassava fibers gave mechanical strength to the composite and improved proton conductor properties. A high fiber dispersion was observed in the matrix. Electric conductivity tests revealed that the membrane had a conductivity of approximately 0.5 Siemens per cm of acidic media.

  18. How muscle fiber lengths and velocities affect muscle force generation as humans walk and run at different speeds.

    Science.gov (United States)

    Arnold, Edith M; Hamner, Samuel R; Seth, Ajay; Millard, Matthew; Delp, Scott L

    2013-06-01

    The lengths and velocities of muscle fibers have a dramatic effect on muscle force generation. It is unknown, however, whether the lengths and velocities of lower limb muscle fibers substantially affect the ability of muscles to generate force during walking and running. We examined this issue by developing simulations of muscle-tendon dynamics to calculate the lengths and velocities of muscle fibers from electromyographic recordings of 11 lower limb muscles and kinematic measurements of the hip, knee and ankle made as five subjects walked at speeds of 1.0-1.75 m s(-1) and ran at speeds of 2.0-5.0 m s(-1). We analyzed the simulated fiber lengths, fiber velocities and forces to evaluate the influence of force-length and force-velocity properties on force generation at different walking and running speeds. The simulations revealed that force generation ability (i.e. the force generated per unit of activation) of eight of the 11 muscles was significantly affected by walking or running speed. Soleus force generation ability decreased with increasing walking speed, but the transition from walking to running increased the force generation ability by reducing fiber velocities. Our results demonstrate the influence of soleus muscle architecture on the walk-to-run transition and the effects of muscle-tendon compliance on the plantarflexors' ability to generate ankle moment and power. The study presents data that permit lower limb muscles to be studied in unprecedented detail by relating muscle fiber dynamics and force generation to the mechanical demands of walking and running.

  19. Structure, sound velocity, and thermal conductivity of the perovskite NdGaO3

    Science.gov (United States)

    Krivchikov, A. I.; Gorodilov, B. Ya.; Kolobov, I. G.; Érenburg, A. I.; Savitskiĭ, D. I.; Ubizskiĭ, S. B.; Syvorotka, I. M.; Vasilechko, L. O.

    2000-05-01

    X-ray (300 K) and ultrasonic (77-270 K) studies and measurements of the thermal conductivity (30-300 K) are carried out on single-crystal samples of NdGaO3 in different crystallographic directions. The values of the lattice parameters of NdGaO3 are refined. The sound velocities in the principal crystallographic directions are measured, and the elastic constants and Debye temperature are calculated. The observed anisotropy of the thermal conductivity is described in the framework of a gaskinetic model and is linked to the anisotropy of the interaction parameters of the acoustical and optical phonons.

  20. Angiotensin II does not acutely regulate conduction velocity in rat atrial tissue

    DEFF Research Database (Denmark)

    Olsen, Kristine B; Braunstein, Thomas H; Sørensen, Charlotte M;

    2011-01-01

    . The aim of the current study was to investigate the acute effect of Ang II on conduction velocity (CV) in atrial tissue from normal and chronically infarcted rats. Methods. Contractile force was measured and CV was determined from the conduction time between electrodes placed on the tissue preparation...... and functional in the free wall preparation. The difference between free wall and auricle was probably not caused by differences in receptor expression since equal amounts of AT1 mRNA were present. To test if myocardial infarction (MI) sensitizes the atrium to Ang II, free atrial wall from rats subjected to 4...

  1. Thermal Conductivity and Raman Spectra of Carbon Fibers

    Science.gov (United States)

    Liu, Xuebo; Dong, Hua; Li, Yan; Mei, Ning

    2017-10-01

    Due to its unique physical properties, carbon fiber (CF) has been widely studied for extensive application in aerospace and machinery. In this study, the thermal diffusivity of three kinds of CF sample is characterized by the transient electrothermal technique at room temperature. By subtracting the effect of radiative losses, the effective thermal diffusivity of CFs can be calculated as 6.46× 10^{-6} m2\\cdot s^{-1}, 6.58× 10^{-6} m2\\cdot s^{-1} and 2.01× 10^{-4} m2\\cdot s^{-1}, respectively. For the first time, the emissivity coefficient of carbon fiber is calibrated as 0.78. Combined with Raman spectra and phonon scattering, we found that the better crystalline structure and low defect in CF have an obvious impact on its thermal diffusivity.

  2. Strong, Light, Multifunctional Fibers of Carbon Nanotubes with Ultrahigh Conductivity

    Science.gov (United States)

    2013-01-11

    coagulation bath . So far, wet spinning from acid has yielded the most highly ordered and dense CNT fibers (14). Yet, their properties have been... coagulants like water (14), thereby sim- plifying the original method (12) by avoiding surfactants in the CNT dispersion and eliminat- ing polymer from the...a spinneret (65- to 130-mm diameter) into a coagulant (acetone or water) to remove the acid. The forming filament was collected onto a winding drum

  3. Preparation of ZnO nanorods on conductive PET-ITO-Ag fibers

    Science.gov (United States)

    Li, Yiwen; Ji, Shuai; Chen, Yuanyu; Zhang, Hong; Gong, Yumei; Guo, Jing

    2016-12-01

    We studied the vertical ZnO nanorods grown on conductive conventional polyethylene terephthalate (PET) fibers which are prepared by electroless silver depositing on tin-doped indium oxide (ITO) coated PET fibers through an efficient and low-cost green approach. The PET fibers were firstly functionalized with a layer of ITO gel synthesized through a sol-gel process at rather low temperature, simply by immersing the fibers into ITO sol for several minutes followed by gelation at 120 °C. Once the ITO gel layer surface was activated by SnCl2, a continuous, uniform, and compact layer of silver was carried out on the surface of the PET-ITO fibers through electroless plating operation at room temperature. The as-prepared PET-ITO-Ag fibers had good electrical conductivity, with surface resistivity as low as 0.23 mΩ cm. The overall procedure is simple, efficient, nontoxic, and controllable. The conductive PET-ITO-Ag fiber was used successfully as a flexible basal material to plant vertical ZnO nanorods through controlling the seeding and growth processes. The morphology of the PET-ITO, PET-ITO-Ag, and PET-ITO-Ag-ZnO fibers were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Undergone the whole process, although the tensile strength of the fiber decreased slightly, they may still exert their applications in flexible electronic such as photovoltaic and piezoelectric devices.

  4. [Nerve conduction velocity of repeater F-waves is identical to that of M-waves].

    Science.gov (United States)

    Hasegawa, O; Matsumoto, S; Gondo, G; Arita, T; Iwasawa, H

    2001-12-01

    F-wave normally varies in latency and waveform from one response to the next. But the number of identical responses in a series of F-waves may be increased with neurogenic atrophy consistent with a decreased number of motoneurons capable of responding to antidromic stimulation. They are called "repeater F-waves". We herein demonstrate some repeater F-waves observed in three patients with moderate or slight diabetic polyneuropathy. In their motor nerve conduction studies on the peroneal nerve the maximum conduction velocity was 33 m/sec in patient 1, 36 m/sec in patient 2 and 48 m/sec in patient 3. A total of 6 delayed indirect potentials were repeatedly evoked after nerve trunk stimulation. They fulfilled the characteristics of F-wave. Their conduction velocities in the leg segment were 27, 26, 23 m/sec in patient 1, 34, 33 m/sec in patient 2 and 46 m/sec in patient 3. Repeater F-waves are occasionally observed in patients with amyotrophic lateral sclerosis, cervical spondylosis or entrapment neuropathies, in which the number of motoneuron is decreased. In diabetic polyneuropathy some repeater F-waves were also observed in patients not only with moderate to severe neuropathy but also with normal nerve conduction. F-waves are generated by an antidromic backfiring of motor neurons, and they occur preferentially in large motor neurons. Larger motor neurons inhibit smaller axons through the activation of Renshaw cells. In our 3 patients conduction velocities of the repeated F-waves were all identical to the main component of M-wave. These observations reconfirmed the hypothesis that relatively large motor neurons generating F-waves are preferentially activated also in repeater F-waves.

  5. An Electromagnetic Gauge Technique for Measuring Shocked Particle Velocity in Electrically Conductive Samples

    Science.gov (United States)

    Cheng, David; Yoshinaka, Akio

    2014-11-01

    Electromagnetic velocity (EMV) gauges are a class of film gauges which permit the direct in-situ measurement of shocked material flow velocity. The active sensing element, typically a metallic foil, requires exposure to a known external magnetic field in order to produce motional electromotive force (emf). Due to signal distortion caused by mutual inductance between sample and EMV gauge, this technique is typically limited to shock waves in non-conductive materials. In conductive samples, motional emf generated in the EMV gauge has to be extracted from the measured signal which results from the combined effects of both motional emf and voltage changes from induced currents. An electromagnetic technique is presented which analytically models the dynamics of induced current between a copper disk moving as a rigid body with constant 1D translational velocity toward an EMV gauge, where both disk and gauge are exposed to a uniform external static magnetic field. The disk is modelled as a magnetic dipole loop where its Foucault current is evaluated from the characteristics of the fields, whereas the EMV gauge is modelled as a circuit loop immersed in the field of the magnetic dipole loop, the intensity of which is calculated as a function of space and, implicitly, time. Equations of mutual induction are derived and the current induced in the EMV gauge loop is solved, allowing discrimination of the motional emf. Numerical analysis is provided for the step response of the induced EMV gauge current with respect to the Foucault current in the moving copper sample.

  6. β-Adrenergic modulation of myocardial conduction velocity: Connexins vs. sodium current.

    Science.gov (United States)

    Campbell, Annabel S; Johnstone, Scott R; Baillie, George S; Smith, Godfrey

    2014-12-01

    The heart is capable of rapid changes in cardiac output: these are caused in large part by changes in the activity of the autonomic nervous system that alter heart rate, force and time course of contraction. While studies of autonomic control have focussed on heart rate and contractile mechanisms, fewer studies have considered the influence of electrical propagation across the chamber. Conduction velocity (CV) of the action potential (AP) is an important variable, which ensures efficient pumping action of the heart and, along with AP duration, is a determinant of the electrical stability of the myocardium. CV depends on multiple factors, including tissue excitability and intercellular resistance: the latter is controlled by the number and arrangement of gap junctions (GJs) linking adjacent cardiac cells. Whole heart studies (in vivo and in vitro) report variable effects of sympathetic nervous system stimulation on ventricular CV, a major complication in interpretation being the accompanying increase in heart rate. At the cellular level, changes in cardiomyocyte electrophysiology, mediated via β-adrenoreceptor (β-AR) activation, alter the AP shape and amplitude but the influence of these effects on the CV is unclear. Alternatively, CV changes may occur via altered GJ conductance, but despite detailed knowledge of the underlying channel protein (connexin), little consensus exists on the extent and time course of the change in GJ conductance induced by AR activation. This review will examine the literature on the modulation of ventricular AP conduction velocity by β-AR activation in a range of physiological preparations and highlight unresolved issues.

  7. Thermal conductivity and sound velocity of antigorite at high pressure using time-domain thermoreflectance

    Science.gov (United States)

    Chien, Y. H.; Hsieh, W. P.

    2016-12-01

    We measure the thermal conductivity and compressional wave velocity of antigorite at room temperature and up to 13 GPa. Antigorite is a serpentine mineral (Mg6Si4O10(OH)8) of high-temperature form having a wavy structure and it has a wide stability field (e.g., up to 720°C at 2 GPa or 620°C at 5 GPa), which is a key material for understanding slab subduction, deep earthquake and volcanic processes in the mantle wedge where fluids from the dehydrating oceanic crust interact with the mantle. The mineral phases, chemical compositions, and crystal orientations of the antigorite were analyzed using Raman spectroscopy, energy-dispersive spectroscopy, and electron backscattered diffraction, respectively. The measurements of thermal conductivities and sound velocities of antigorite with different crystal orientations were carried out by time-domain thermoreflectance (TDTR). At Pconductivity becomes more anisotropic with increasing pressure but becomes more isotropic in elastic property between b and c-axis. We also discuss the lattice internal rearrangement may induce over three times increase in thermal conductivity at 7 GPa ( 210 km depth) which would enhance larger heat flux along b-axis in the serpentinized slab. Thus, it gives new insights into the potential influence of thermal conductivity anisotropy on the mineral dehydration processes in the subduction zone.

  8. PIC Simulations of the Effect of Velocity Space Instabilities on Electron Viscosity and Thermal Conduction

    Science.gov (United States)

    Riquelme, Mario A.; Quataert, Eliot; Verscharen, Daniel

    2016-06-01

    In low-collisionality plasmas, velocity-space instabilities are a key mechanism providing an effective collisionality for the plasma. We use particle-in-cell (PIC) simulations to study the interplay between electron- and ion-scale velocity-space instabilities and their effect on electron pressure anisotropy, viscous heating, and thermal conduction. The adiabatic invariance of the magnetic moment in low-collisionality plasmas leads to pressure anisotropy, {{Δ }}{p}j\\equiv {p}\\perp ,j-{p}\\parallel ,j\\gt 0, if the magnetic field {\\boldsymbol{B}} is amplified ({p}\\perp ,j and {p}\\parallel ,j denote the pressure of species j (electron, ion) perpendicular and parallel to {\\boldsymbol{B}}). If the resulting anisotropy is large enough, it can in turn trigger small-scale plasma instabilities. Our PIC simulations explore the nonlinear regime of the mirror, IC, and electron whistler instabilities, through continuous amplification of the magnetic field | {\\boldsymbol{B}}| by an imposed shear in the plasma. In the regime 1≲ {β }j≲ 20 ({β }j\\equiv 8π {p}j/| {\\boldsymbol{B}}{| }2), the saturated electron pressure anisotropy, {{Δ }}{p}{{e}}/{p}\\parallel ,{{e}}, is determined mainly by the (electron-lengthscale) whistler marginal stability condition, with a modest factor of ˜1.5-2 decrease due to the trapping of electrons into ion-lengthscale mirrors. We explicitly calculate the mean free path of the electrons and ions along the mean magnetic field and provide a simple physical prescription for the mean free path and thermal conductivity in low-collisionality β j ≳ 1 plasmas. Our results imply that velocity-space instabilities likely decrease the thermal conductivity of plasma in the outer parts of massive, hot, galaxy clusters. We also discuss the implications of our results for electron heating and thermal conduction in low-collisionality accretion flows onto black holes, including Sgr A* in the Galactic Center.

  9. Relations among threshold, spike height, electrode distance, and conduction velocity in electrical stimulation of certain medullospinal neurons.

    Science.gov (United States)

    Hentall, I D; Zorman, G; Kansky, S; Fields, H L

    1984-05-01

    This report describes how the threshold for extracellular, electrical stimulation of cell bodies in the rat's rostromedial medulla depends on the distance to the stimulating electrode. A monopolar microelectrode both delivered current pulses near medullospinal neurons and, after decay of the stimulus artifact, detected whether an orthodromic spike had occurred by collision of that spike with a suitably timed antidromic spike initiated at the thoracic spinal cord. The liminal current and the height of antidromic spikes were noted at a series of vertical electrode positions. Regression analysis was performed to determine whether threshold and the inverse of peak-to-peak spike height varied more as the radial distance or its square. The square relationship provided a much better fit for threshold and a marginally better fit for the inverse of spike height. The spatial decline in excitability (K2) averaged 859 microA/mm2, falling within the range of values found for fibers and cell bodies in other studies. The constant of spatial decline in spike height (C2) in millivolts per square millimeter was positively correlated with K2. Both C2 and K2 were negatively correlated with conduction velocity. From threshold distance curves fitted by regression analysis, the mean separation of sites of spike maxima and threshold minima along each electrode path was 16 micron; the estimated distance from these sites to, respectively, the loci of spike generation and spike excitation were positively correlated and similar. The variation of C2 and K2 with conduction velocity may be due either to an influence of the size and shape of the dendritic tree on the spatial decrement of excitability and spike height or to a confounding in the studied equations of the space-independent effect of the size of a cell body on spike height and excitability.

  10. Hybrid boron nitride-natural fiber composites for enhanced thermal conductivity.

    Science.gov (United States)

    Xia, Changlei; Garcia, Andres C; Shi, Sheldon Q; Qiu, Ying; Warner, Nathaniel; Wu, Yingji; Cai, Liping; Rizvi, Hussain R; D'Souza, Nandika A; Nie, Xu

    2016-10-05

    Thermal conductivity was dramatically increased after adding natural fiber into hexagonal boron nitride (hBN)/epoxy composites. Although natural fiber does not show high-thermal conductivity itself, this study found that the synergy of natural fiber with hBN could significantly improve thermal conductivity, compared with that solely using hBN. A design of mixtures approach using constant fibers with increasing volume fractions of hBN was examined and compared. The thermal conductivity of the composite containing 43.6% hBN, 26.3% kenaf fiber and 30.1% epoxy reached 6.418 W m(-1) K(-1), which was 72.3% higher than that (3.600 W m(-1) K(-1)) of the 69.0% hBN and 31.0% epoxy composite. Using the scanning electron microscope (SEM) and micro computed tomography (micro-CT), it was observed that the hBN powders were well distributed and ordered on the fiber surfaces enhancing the ceramic filler's interconnection, which may be the reason for the increase in thermal conductivity. Additionally, the results from mechanical and dynamic mechanical tests showed that performances dramatically improved after adding kenaf fibers into the hBN/epoxy composite, potentially benefiting the composite's use as an engineered material.

  11. Hybrid boron nitride-natural fiber composites for enhanced thermal conductivity

    Science.gov (United States)

    Xia, Changlei; Garcia, Andres C.; Shi, Sheldon Q.; Qiu, Ying; Warner, Nathaniel; Wu, Yingji; Cai, Liping; Rizvi, Hussain R.; D’Souza, Nandika A.; Nie, Xu

    2016-10-01

    Thermal conductivity was dramatically increased after adding natural fiber into hexagonal boron nitride (hBN)/epoxy composites. Although natural fiber does not show high-thermal conductivity itself, this study found that the synergy of natural fiber with hBN could significantly improve thermal conductivity, compared with that solely using hBN. A design of mixtures approach using constant fibers with increasing volume fractions of hBN was examined and compared. The thermal conductivity of the composite containing 43.6% hBN, 26.3% kenaf fiber and 30.1% epoxy reached 6.418 W m‑1 K‑1, which was 72.3% higher than that (3.600 W m‑1 K‑1) of the 69.0% hBN and 31.0% epoxy composite. Using the scanning electron microscope (SEM) and micro computed tomography (micro-CT), it was observed that the hBN powders were well distributed and ordered on the fiber surfaces enhancing the ceramic filler’s interconnection, which may be the reason for the increase in thermal conductivity. Additionally, the results from mechanical and dynamic mechanical tests showed that performances dramatically improved after adding kenaf fibers into the hBN/epoxy composite, potentially benefiting the composite’s use as an engineered material.

  12. Low Velocity Impact Behavior of Glass Filled Fiber-Reinforced Thermoplastic Engine Components

    Directory of Open Access Journals (Sweden)

    Zakaria Mouti

    2010-03-01

    Full Text Available This paper concerns automotive parts located underneath the engine and in particular the engine oil pan. Classically made of stamped steel or cast aluminum, new developments have allowed the manufacture oil pans with polyamide 66 reinforced by 35% weight of short glass fiber. However, polyamides have some limitations and the most significant is their response to localized impact loading. The nature of the impact considered here is of a typical stone collected from the road and projected into the oil pan. Low velocity impact investigations were carried out using a gas gun and drop weight tower. The study shows that the design of the oil pan has a significant contribution in the shock absorption. In addition to the material properties, the geometry and the ribbing both cleverly combined, increase the impact resistance of the component significantly. Areas of oil pan design improvement have been identified and conclusions drawn.

  13. Tidal reversal and flow velocities using temperature and specific conductance in a small wetland creek

    Science.gov (United States)

    Eaton, Timothy T.

    2016-11-01

    Characterizing flow dynamics in very small tidal creeks is complicated and not well suited to methods developed for upland streams or coastal estuaries, due to low flows, bidirectionality and shallow waters. Simple instrumentation enables thermal and salinity signals to be used to observe flow directions and estimate velocities in these settings. Using multiple inexpensive sensors over 500 m along a tidally influenced wetland creek, I demonstrate how advection of temperature and specific conductance pulses reveal flood and ebb tides and the temporary reversal of flow by warmer, estuarine water from the receiving embayment. The sequential rise of temperature upstream was most evident under hot and dry conditions, after daily peak air temperatures of 25 °C or above, and was subdued or disrupted under cooler or rainy conditions in summertime. Changes in specific conductance at successive sites upstream were less susceptible to environmental influences and confirm tidal flood velocity of between 0.07 and 0.37 m/s. The tidally-induced flow reversal suggests that periodic high tide conditions can interfere with rapid dispersal of pollution discharges, such as from the combined sewer overflow (CSO) located upstream of the studied creek reach. This low-cost approach of temperature and specific conductance sensing in vegetated coastal wetlands where access, precise elevation control and creek discharge measurements are difficult, provides a simple way of tracking water masses when sufficient contrast exists between water sources.

  14. Mechanical muscle fibre conduction velocity of the biceps as measured by a new seismic technique.

    Science.gov (United States)

    Journée, H L; de Jonge, A B; van Calker, R; Gräler, G

    1995-01-01

    A recently-developed technique, called seismic myography (SMG) has the characteristic of recording fast micro-mechanical response times. These times can be determined with sub-millisecond accuracy. The response times can be compared to response times of EMG recordings. The "muscular electro-seismic response" (MESR) latencies, due to direct electrical stimulation of the biceps muscle, are used for explorative measurements of the mechanical conduction velocity of the muscle fibres. The measurements are performed by means of a general-purpose physiological multimeter which is equiped with the micro-seismic function. Measurements are performed on two healthy subjects, aged 22 years. The MESR-latencies are measured along a medial and a lateral trajectory on their biceps muscles. The MESR-latencies at stimulus-cathodal to seismic transducer distances of 2,0-3,5 cm, are in the range of 2.0-3.8 ms, while at distances in the range of 7.5-8.9 cm the MESR-latencies varied between 3.4 and 4.7 ms. The calculated mechanical muscle fibre conduction velocities (MMFCV) are in the range between 36 and 89 m/s. There is a reproducability error of maximum 20%. The MMFCV's of the lateral and medial trajectory do not differ within the accuracy of the present method. However, the MMFCV's are considerably higher than the electrical muscle fibre conduction velocities of MUAPS ((E)MFCV). Some aspects of the MMFCV and possible consequences to surface EMG recordings are discussed. It is concluded that this seismic method for measuring MMFCV is a new accessible and simple to handle tool for the description of muscle function, and offers an interesting new contribution in experimental muscular research.

  15. Investigations on Thermal Conductivities of Jute and Banana Fiber Reinforced Epoxy Composites

    Science.gov (United States)

    Pujari, Satish; Ramakrishna, Avasarala; Balaram Padal, Korabu Tulasi

    2017-04-01

    The Jute and Banana fibers are used as reinforcement in epoxy resin matrix for making partially green biodegradable material composite via hand lay-up technique. The thermal conductivity of the jute fiber epoxy composites and banana fiber epoxy composites at different volume fraction of the fiber is determined experimentally by using guarded heat flow meter method. The experimental results had shown that thermal conductivity of the composites decrease with an increase in the fiber content. Experimental results are compared with theoretical models (Series model, Hashin model and Maxwell model) to describe the variation of the thermal conductivity versus the volume fraction of the fiber. Good agreement between theoretical and experimental results is observed. Thermal conductivity of Banana fiber composite is less when compared to that of Jute composite which indicates banana is a good insulator and also the developed composites can be used as insulating materials in building, automotive industry and in steam pipes to save energy by reducing rate of heat transfer.

  16. Investigations on Thermal Conductivities of Jute and Banana Fiber Reinforced Epoxy Composites

    Science.gov (United States)

    Pujari, Satish; Ramakrishna, Avasarala; Balaram Padal, Korabu Tulasi

    2016-01-01

    The Jute and Banana fibers are used as reinforcement in epoxy resin matrix for making partially green biodegradable material composite via hand lay-up technique. The thermal conductivity of the jute fiber epoxy composites and banana fiber epoxy composites at different volume fraction of the fiber is determined experimentally by using guarded heat flow meter method. The experimental results had shown that thermal conductivity of the composites decrease with an increase in the fiber content. Experimental results are compared with theoretical models (Series model, Hashin model and Maxwell model) to describe the variation of the thermal conductivity versus the volume fraction of the fiber. Good agreement between theoretical and experimental results is observed. Thermal conductivity of Banana fiber composite is less when compared to that of Jute composite which indicates banana is a good insulator and also the developed composites can be used as insulating materials in building, automotive industry and in steam pipes to save energy by reducing rate of heat transfer.

  17. The PRL Stabilized High Resolution Echelle Fiber-fed Spectrograph: Instrument Description & First Radial Velocity Results

    CERN Document Server

    Chakraborty, Abhijit; Roy, Arpita; Dixit, Vaibhav; Richardson, Eric Harvey; Dongre, Varun; Pathan, F M; Chaturvedi, Priyanka; Shah, Vishal; Ubale, Girish P; Anandarao, B G

    2013-01-01

    We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mt Abu 1.2 m telescope, in India. Data obtained as part of the post-commissioning tests with PARAS show velocity precision better than 2m/s over a period of several months on bright RV standard stars. For observations of sigma-Dra we report 1.7m/s precision for a period of seven months and 2.1m/s for HD 9407 over a period of 2 months. PARAS is capable of a single-shot spectral coverage of 3800A - 9500A at a resolution of about 67,000. The RV results were obtained between 3800A and 6900A using simultaneous wavelength calibration with a Thorium-Argon (ThAr) hollow cathode lamp. The spectrograph is maintained under stable conditions of temperature with a precision of 0.01 - 0.02C (rms) at 25.55C, and enclosed in a vacuum vessel at pressure of 0.1 +/-0.03 mbar. The blaze peak efficiency of the spectrograp...

  18. Tuning the conductivity and inner structure of electrospun fibers to promote cardiomyocyte elongation and synchronous beating.

    Science.gov (United States)

    Liu, Yaowen; Lu, Jinfu; Xu, Guisen; Wei, Jiaojun; Zhang, Zhibin; Li, Xiaohong

    2016-12-01

    The key to addressing the challenges facing cardiac tissue engineering is the integration of physical, chemical, and electrical cues into scaffolds. Aligned and conductive scaffolds have been fabricated as synthetic microenvironments to improve the function of cardiomyocytes. However, up to now, the influence of conductive capability and inner structure of fibrous scaffolds have not been determined on the cardiomyocyte morphologies and beating patterns. In the current study, highly aligned fibers were fabricated with loaded up to 6% of carbon nanotubes (CNTs) to modulate the electrical conductivity, while blend and coaxial electrospinning were utilized to create a bulk distribution of CNTs in fiber matrices and a spatial embedment in fiber cores, respectively. Conductive networks were formed in the fibrous scaffolds after the inoculation of over 3% CNTs, and the increase in the conductivity could maintain the cell viabilities, induce the cell elongation, enhance the production of sarcomeric α-actinin and troponin I, and promote the synchronous beating of cardiomyocytes. Although the conductivity of blend fibers is slightly higher than that of coaxial fibers with the same CNT loadings, the lower exposures to CNTs resulted in higher cell viability, elongation, extracellular matrix secretion and beating rates for cardiomyocytes on coaxial fibers. Taken altogether, core-sheath fibers with loaded 5% of CNTs in the fiber cores facilitated the cardiomyocyte growth with a production of organized contractile proteins and a pulsation frequency close to that of the atrium. It is suggested that electrospun scaffolds that couple conductivity and fibrous structure considerations may provide optimal stimuli to foster cell morphology and functions for myocardial regeneration or establishment of in vitro cardiomyocyte culture platform for drug screening.

  19. Prediction of rocks thermal conductivity from elastic wave velocities, mineralogy and microstructure

    Science.gov (United States)

    Pimienta, Lucas; Sarout, Joel; Esteban, Lionel; Piane, Claudio Delle

    2014-05-01

    While knowledge on Thermal Conductivity (TC) of rocks is of interest in many fields, determining this property remains challenging. In this paper, a modelling approach for TC prediction from Elastic Wave Velocity (EWV) measurements is reported. To this end, a new effective TC model for a typical sedimentary rock is introduced that explicitly accounts for the presence of pores, pressure-sensitive microcracks (or grain contacts) and formation fluids. A model of effective elasticity is also devised for this same rock that links its microstructural characteristics to the velocity of elastic waves. The two models are based on the same effective medium approach and involve the same microstructural parameters. A workflow based on this explicit modelling approach is devised that allows for the prediction of the TC of a reservoir rock using (i) the elastic waves velocities, (ii) the dominant mineral content and (iii) the bulk porosity. This workflow is validated using experimental data reported in the literature for dry and water-saturated Fontainebleau and Berea sandstones. The datasets include measurements of TC and EWV as a function of effective pressure. In addition, it is shown that the dependence of TC on the rock microstructure is formally and practically similar to that of EWV. It is also demonstrated that the accuracy of TC predictions from EWV increases with effective pressure (burial depth). The underlying assumptions and limitations of the present approach together with the effect of burial are discussed.

  20. Electrical conductivity improvement of aeronautical carbon fiber reinforced polyepoxy composites by insertion of carbon nanotubes

    OpenAIRE

    Lonjon, Antoine; Demont, Philippe; Dantras, Eric; Lacabanne, Colette

    2012-01-01

    International audience; An increase and homogenization of electrical conductivity is essential in epoxy carbon fiber laminar aeronautical composites. Dynamic conductivity measurements have shown a very poor transversal conductivity. Double wall carbon nanotubes have been introduced into the epoxy matrix to increase the electrical conductivity. The conductivity and the degree of dispersion of carbon nanotubes in epoxy matrix were evaluated. The epoxy matrix was filled with 0.4 wt.% of CNTs to ...

  1. Evaluation of central and peripheral fatigue in the quadriceps using fractal dimension and conduction velocity in young females.

    Directory of Open Access Journals (Sweden)

    Matteo Beretta-Piccoli

    Full Text Available Over the past decade, linear and non-linear surface electromyography descriptors for central and peripheral components of fatigue have been developed. In the current study, we tested fractal dimension (FD and conduction velocity (CV as myoelectric descriptors of central and peripheral fatigue, respectively. To this aim, we analyzed FD and CV slopes during sustained fatiguing contractions of the quadriceps femoris in healthy humans.A total of 29 recreationally active women (mean age±standard deviation: 24±4 years and two female elite athletes (one power athlete, age 24 and one endurance athlete, age 30 years performed two knee extensions: (1 at 20% maximal voluntary contraction (MVC for 30 s, and (2 at 60% MVC held until exhaustion. Surface EMG signals were detected from the vastus lateralis and vastus medialis using bidimensional arrays.Central and peripheral fatigue were described as decreases in FD and CV, respectively. A positive correlation between FD and CV (R=0.51, p<0.01 was found during the sustained 60% MVC, probably as a result of simultaneous motor unit synchronization and a decrease in muscle fiber CV during the fatiguing task.Central and peripheral fatigue can be described as changes in FD and CV, at least in young, healthy women. The significant correlation between FD and CV observed at 60% MVC suggests that a mutual interaction between central and peripheral fatigue can arise during submaximal isometric contractions.

  2. Development of potassium ion conducting hollow glass fibers. [potassium sulfur battery

    Science.gov (United States)

    Tsang, F. Y.

    1974-01-01

    Potassium ion conducting glasses, chemically resistant to potassium, potassium sulfide and sulfur, were made and their possible utility as the membrane material for a potassium/sulfur battery was evaluated. At least one satisfactory candidate was found. It possesses an electrical resistance which makes it usable as a membrane in the form of a fine hollow fiber. It's chemical and electrochemical resistances are excellent. The other aspects of the possible potassium sulfur battery utilizing such fine hollow fibers, including the header (or tube sheet) and a cathode current collector were studied. Several cathode materials were found to be satisfactory. None of the tube sheet materials studied possessed all the desired properties. Multi-fiber cells had very limited life-time due to physical failure of fibers at the fiber/tube sheet junctions.

  3. Electrically conducting nanobiocomposites using carbon nanotubes and collagen waste fibers

    Energy Technology Data Exchange (ETDEWEB)

    Meiyazhagan, Ashokkumar; Thangavel, Saravanamoorthy [Advanced Materials Laboratory, Center for Leather Apparel & Accessories Development, Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600020 (India); Hashim, Daniel P.; Ajayan, Pulickel M. [Department of Materials Science and NanoEngineering, Rice University, Houston, TX 77005 (United States); Palanisamy, Thanikaivelan, E-mail: thanik8@yahoo.com [Advanced Materials Laboratory, Center for Leather Apparel & Accessories Development, Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600020 (India)

    2015-05-01

    Electrically conducting hybrid biocomposite films were prepared using a simple and cost-effective method by incorporating different types of carbon nanotubes (XCNTs) viz., few walled carbon nanotube (FWCNT) and boron doped carbon nanotube (BCNT) into biopolymers. Collagen extracted from animal skin wastes was blended with guar gum and XCNTs in varying proportions to form flexible and electrically conducting hybrid films. We found that the electrical conductivity of both types of hybrid films increases radically as the XCNT loading increases. BCNT incorporated hybrid films show better electrical conductivity (3.0 × 10{sup −1} S/cm) than their FWCNT loaded counter parts (4.8 × 10{sup −4} S/cm) at a dosage of 2 wt.%. On the other hand, mechanical and other physical properties such as transparency, flexibility and surface smoothness of the developed hybrid films were affected as a function of XCNT concentration. We also demonstrated that the developed hybrid films lit up a LED lamp when inserted between batteries and the brightness of the emitted light depended on the XCNT loading. These results suggest a new way to transform an industrial biowaste into innovative advanced materials for applications in fields related to biomedicine, biosensors and electronics. - Highlights: • Hybrid nanobiocomposite films prepared using collagen, guar gum and CNTs. • Examined the effect of CNT doping on the properties of hybrid biocomposite films. • Higher CNT loading improved the conductivity radically, especially for BCNT. • The ability of developed hybrid films to lit up a LED lamp was demonstrated. • The results suggest a new way to transform biowaste into advanced materials.

  4. Extraordinarily High Conductivity of Stretchable Fibers of Polyurethane and Silver Nanoflowers.

    Science.gov (United States)

    Ma, Rujun; Kang, Byeongguk; Cho, Suik; Choi, Minjun; Baik, Seunghyun

    2015-11-24

    Stretchable conductive composites have received considerable attention recently, and they should have high conductivity and mechanical strength. Here we report highly conductive stretchable fibers synthesized by the scalable wet spinning process using flower-shaped silver nanoparticles with nanodisc-shaped petals (Ag nanoflowers) and polyurethane. An extraordinarily high conductivity (41,245 S cm(-1)) was obtained by Ag nanoflowers, which is 2 orders of magnitude greater than that of fibers synthesized using spherical Ag nanoparticles. This was due to the enhanced surface area and vigorous coalescence of nanodisc-shaped petals during the curing process. There was a trade-off relationship between conductivity and stretchability, and the maximum rupture strain was 776%. An analytical model revealed that the enhanced adhesion between Ag nanoflowers and polyurethane provided a high Young's modulus (731.5 MPa) and ultimate strength (39.6 MPa) of the fibers. The fibers exhibited an elastic property after prestretching, and the resistance change of weft-knitted fabric was negligible up to 200% strain. The fibers with extraordinarily high conductivity, stretchability, and mechanical strength may be useful for wearable electronics applications.

  5. Fibers and Conductive Films Using Silver Nanoparticles and Nanowires by Near-Field Electrospinning Process

    Directory of Open Access Journals (Sweden)

    Cheng-Tang Pan

    2015-01-01

    Full Text Available The silver nanowires (AgNWs and silver nanoparticles (AgNPs were synthesized. With near-field electrospinning (NFES process, fibers and thin films with AgNPs and AgNWs were fabricated. In the NFES process, 10 k voltage was applied and the AgNPs and AgNWs fibers can be directly orderly collected without breaking and bending. Then, the characteristics of the fibers were analyzed by four-point probe and EDS. The conductive film was analyzed. When the thickness of films with AgNWs and AgNPs was 1.6 µm, the sheet resistance of films was 0.032 Ω/sq which was superior to that of the commercial ITO. The transmissivity of films was analyzed. The transmissivity was inversely proportional to sheet resistance of the films. In the future, the fibers and films can be used as transparent conductive electrodes.

  6. Oscillatory conductive heat transfer for a fiber in an ideal gas

    Science.gov (United States)

    Kuntz, H. L.; Perreira, N. D.

    1985-01-01

    A description of the thermal effects created by placing a cylindrical fiber in an inviscid, ideal gas, through which an acoustic wave propagates, is presented. The fibers and the gas have finite heat capacities and thermal conductivities. Expressions for the temperature distribution in the gas and in the material are determined. The temperature distribution is caused by pressure oscillations in the gas which, in turn, are caused by the passage of an acoustic wave. The relative value of a dimensionless parameter is found to be indicative of whether the exact or approximate equations should be used in the solution. This parameter is a function of the thermal conductivities and heat capacities of the fiber and gas, the acoustic frequency, and the fiber diameter.

  7. Downsized Sheath-Core Conducting Fibers for Weavable Superelastic Wires, Biosensors, Supercapacitors, and Strain Sensors.

    Science.gov (United States)

    Wang, Hongyan; Liu, Zunfeng; Ding, Jianning; Lepró, Xavier; Fang, Shaoli; Jiang, Nan; Yuan, Ninyi; Wang, Run; Yin, Qu; Lv, Wei; Liu, Zhongsheng; Zhang, Mei; Ovalle-Robles, Raquel; Inoue, Kanzan; Yin, Shougen; Baughman, Ray H

    2016-07-01

    Hair-like-diameter superelastic conducting fibers, comprising a buckled carbon nanotube sheath on a rubber core, are fabricated, characterized, and deployed as weavable wires, biosensors, supercapacitors, and strain sensors. These downsized sheath-core fibers provide the demonstrated basis for glucose sensors, supercapacitors, and electrical interconnects whose performance is undegraded by giant strain, as well as ultrafast strain sensors that exploit strain-dependent capacitance changes.

  8. RTA-treated carbon fiber/copper core/shell hybrid for thermally conductive composites.

    Science.gov (United States)

    Yu, Seunggun; Park, Bo-In; Park, Cheolmin; Hong, Soon Man; Han, Tae Hee; Koo, Chong Min

    2014-05-28

    In this paper, we demonstrate a facile route to produce epoxy/carbon fiber composites providing continuous heat conduction pathway of Cu with a high degree of crystal perfection via electroplating, followed by rapid thermal annealing (RTA) treatment and compression molding. Copper shells on carbon fibers were coated through electroplating method and post-treated via RTA technique to reduce the degree of imperfection in the Cu crystal. The epoxy/Cu-plated carbon fiber composites with Cu shell of 12.0 vol % prepared via simple compression molding, revealed 18 times larger thermal conductivity (47.2 W m(-1) K(-1)) in parallel direction and 6 times larger thermal conductivity (3.9 W m(-1) K(-1)) in perpendicular direction than epoxy/carbon fiber composite. Our novel composites with RTA-treated carbon fiber/Cu core/shell hybrid showed heat conduction behavior of an excellent polymeric composite thermal conductor with continuous heat conduction pathway, comparable to theoretical values obtained from Hatta and Taya model.

  9. PIC Simulations of the Effect of Velocity Space Instabilities on Electron Viscosity and Thermal Conduction

    CERN Document Server

    Riquelme, Mario; Verscharen, Daniel

    2016-01-01

    In low-collisionality plasmas, velocity-space instabilities are a key mechanism providing an effective collisionality for the plasma. We use particle-in-cell (PIC) simulations to study the interplay between electron and ion-scale velocity-space instabilities and their effect on electron pressure anisotropy, viscous heating, and thermal conduction. The adiabatic invariance of the magnetic moment in low-collisionality plasmas leads to pressure anisotropy, $p_{\\perp,j} > p_{||,j}$, if the magnetic field $\\vec{B}$ is amplified ($p_{\\perp,j}$ and $p_{||,j}$ denote the pressure of species $j$ [electron, ion] perpendicular and parallel to $\\vec{B}$). If the resulting anisotropy is large enough, it can in turn trigger small-scale plasma instabilities. Our PIC simulations explore the nonlinear regime of the mirror, ion-cyclotron, and electron whistler instabilities, through continuous amplification of the magnetic field $|\\vec{B}|$ by an imposed shear in the plasma. In the regime $1 \\lesssim \\beta_j \\lesssim 20$ ($\\be...

  10. Determining the relationship of thermal conductivity and compressional wave velocity of common rock types as a basis for reservoir characterization

    Science.gov (United States)

    Mielke, P.; Bär, K.; Sass, I.

    2017-05-01

    A comprehensive dataset detailing thermal conductivity and acoustic (compressional) wave velocity of 1430 oven-dry rock samples from clastic sedimentary (sandstone, arkose, greywacke), carbonatic (limestone, marl, dolomite, marble, coquina), plutonic (gabbro, gabbrodiorite, diorite, granodiorite, granite) and volcanic (basalt, andesite, rhyolite) rock types is presented. Correlation of thermal conductivity, compressional wave velocity and porosity are discussed in detail for each tested rock type. The study confirms that thermal conductivity of dry rocks can be predicted from acoustic velocity for porous rock types such as volcanites and sandstones, while non- and low-porous rocks show no to minor trends. With a prediction accuracy ± 0.5 W m- 1 K- 1 and a confidence of > 80% for sediments and mafic volcanites the calculated data is far more comprehensive than data collected from literature, and is likely accurate enough for most first exploration approaches or geoscientific models before detailed site-scale investigation or modelling is conducted. To investigate the effect of water saturation on thermal conductivity and compressional wave velocity 118 sedimentary samples (arkose and fine-, medium- and coarse sandstones) were saturated in de-aired water and the heat conduction and acoustic velocity were remeasured. The obtained data shows that both thermal conductivity and compressional wave velocity of saturated samples markedly increase in contrast to dry samples. The extent of the thermal conductivity and compressional wave velocity gain is mainly controlled by porosity. Thermal conductivity of saturated samples increases twice as much for higher porous samples than for low porous fine and medium sandstones. In contrast, the gain of compressional wave velocity of saturated sandstones decreases with increasing porosity.

  11. Experimental studies of electrical conductivities and P-wave velocities of gabbro at high pressures and high temperatures

    Institute of Scientific and Technical Information of China (English)

    白利平; 杜建国; 刘巍; 周文戈

    2003-01-01

    The P-wave velocities and electrical conductivities of gabbro were measured using ultrasonic transmission method and impedance spectroscopy from room temperature to 1100℃ at 1-2 GPa, and the factors controlling the P-wave velocity and the microscopic conductance mechanisms of the rock were analyzed. The experimental results show that the P-wave velocities of gabbro drop abruptly at temperatures of 800-850℃ and under pressures of 1-2 GPa due to the occurrence of grain boundary phases and dehydration melting; however, the electrical conductivities and electronic conduction mechanisms have not changed obviously at temperatures of 800-850℃. At temperatures Below 680℃, only one impedance arc (I) corresponding to grain interior conduction occurs at frequencies between 12 Hz and 105 Hz, the second arc (II) corresponding to grain boundary conduction occurs at temperatures above 680℃. The total conductivity of this rock is dominated by the grain interior conductivity as the occurrence of grain boundary conduction has a small effect on the total conductivity. The laboratory-measured velocities are consistent with the average P-wave velocity observations of lower crust and upper mantle. The conductivity values correspond well with the gabbroite composition of the lower crust and upper mantle; however, they are about 1-2 orders of magnitude lower than MT data from the high conductive layers. The experiments confirm that the dehydration of hydrous minerals can induce the partial melting, and the low seismic velocity zones might be correlated with the high conductive layers if partial melting occurs.

  12. HEIGHT, WEIGHT, BMI, FBS, PPBS, CORRELATED WITH NERVE CONDUCTION VELOCITY IN TYPE II DIABETES MELLITUS PATIENTS

    Directory of Open Access Journals (Sweden)

    Athikari ChandraSekhar

    2014-02-01

    Full Text Available Aims: To look for changes in nerve conduction velocity (NCV in newly diagnosed type II diabetic subjects. To compare the nerve conduction velocity studies of both sensory and motor nerves in upper and lower limb are correlated with height, weight, BMI, fasting and PPBS. Materials and Methods: The study comprises of 40 subjects, 25 subjects were male and 15 subjects were female aged between 38-62 years. All the patents are on oral hypoglycaemic agents. Random sampling techniques were applied for the criteria of sample selection. Results: The mean MCV was significantly lower in type II diabetics common peroneal nerve (38.37±9.43 m/s and posterior tibial nerve (9.78±9.39 m/s. The mean SNC in the type II diabetes median nerve 43.25±11.64, ulnar nerve 43.62±15.77 m/sec sural nerve 38.27±14.32 m/sec and posterior tibial nerve 33.51±20.39. The height mean 163.53±7.23 cm, weight mean 66.98±8.70 kg, BMI 25.10±3.29, FBS mean 158.70±56.58 mg/dl and PPBS mean 223.68±67.95 mg/dl. Abnormal MCV, SCV was found to be associated with FBS and PPBS. Conclusion: Hyperglycaemia is a well established risk factor in type 2 diabetic subjects. Other parameters correlated with Height, Weight, BMI, FBS, PPBS increases most recognized neurological complications. Predominately sensorimotor distal polyneuropathy is the most common of the diabetic neuropathy. Distal sensorimotor polyneuropathy. In our study conducted the changes of diabetic neuropathy affected sensorimotor nerves in both limbs. Nerve conduction studies not only used to diagnose the DM but also monitor the effects of treatment of DM by regular NCS good glycemic control, symptoms of diabetic neuropathy can be reversed and further complication like foot ulceration.

  13. Numerical simulating and experimental study on the woven carbon fiber-reinforced composite laminates under low-velocity impact

    Science.gov (United States)

    Liu, Hanyang; Tang, Zhanwen; Pan, Lingying; Zhao, Weidong; Sun, Baogang; Jiang, Wenge

    2016-05-01

    Impact damage has been identified as a critical form of the defects that constantly threatened the reliability of composite structures, such as those used in the aerospace structures and systems. Low energy impacts can introduce barely visible damage and cause the degradation of structural stiffness, furthermore, the flaws caused by low-velocity impact are so dangerous that they can give rise to the further extended delaminations. In order to improve the reliability and load carrying capacity of composite laminates under low-velocity impact, in this paper, the numerical simulatings and experimental studies on the woven fiber-reinforced composite laminates under low-velocity impact with impact energy 16.7J were discussed. The low velocity impact experiment was carried out through drop-weight system as the reason of inertia effect. A numerical progressive damage model was provided, in which the damages of fiber, matrix and interlamina were considered by VUMT subroutine in ABAQUS, to determine the damage modes. The Hashin failure criteria were improved to cover the failure modes of fiber failure in the directions of warp/weft and delaminations. The results of Finite Element Analysis (FEA) were compared with the experimental results of nondestructive examination including the results of ultrasonic C-scan, cross-section stereomicroscope and contact force - time history curves. It is found that the response of laminates under low-velocity impact could be divided into stages with different damage. Before the max-deformation of the laminates occurring, the matrix cracking, fiber breakage and delaminations were simulated during the impactor dropping. During the releasing and rebounding period, matrix cracking and delaminations areas kept increasing in the laminates because of the stress releasing of laminates. Finally, the simulating results showed the good agreements with the results of experiment.

  14. Determining the group velocity dispersion by field analysis for the LP0X, LP1X, and LP2X mode groups independently of the fiber length: applications to step-index fibers

    DEFF Research Database (Denmark)

    Israelsen, Stine Møller; Usuga Castaneda, Mario A.; Rottwitt, Karsten

    2017-01-01

    By knowing the electric field distribution of a guided mode in an optical fiber, we are able to evaluate the group velocity dispersion in a weakly guiding step-index fiber for a pure mode in the LP0X, LP1X, and LP2X mode groups independently of the fiber length. We demonstrate the method...

  15. The effect of fiber orientation on volume measurement using conductance catheter techniques.

    Science.gov (United States)

    Thaijiam, C; Gale, T J

    2006-01-01

    Estimation of parallel conductance using the impedance electrode technique is usually done assuming isotropic conditions. This may not be the best solution since the myocardium is an anisotropic material. This paper exposes the effect of fiber orientation for volume measurement using a conductor model with asymmetrical source electrodes. Simulation results show calculated volumes between surrounding materials with and without myocardial fiber orientation included in the model. We plan to extend these study results to the real heart for developing conductance catheter techniques for use in blood volume measurements in the right ventricle.

  16. Effects of Bed Rest on Conduction Velocity of the Triceps Surae Stretch Reflex and Postural Control

    Science.gov (United States)

    Reschke, M. F.; Wood, S. J.; Cerisano, J. M.; Kofman, I. S.; Fisher, E. A.; Esteves, J. T.; Taylor, L. C.; DeDios, Y. E.; Harm, D. L.

    2011-01-01

    Despite rigorous exercise and nutritional management during space missions, astronauts returning from microgravity exhibit neuromuscular deficits and a significant loss in muscle mass in the postural muscles of the lower leg. Similar changes in the postural muscles occur in subjects participating in long-duration bed rest studies. These adaptive muscle changes manifest as a reduction in reflex conduction velocity during head-down bed rest. Because the stretch reflex encompasses both the peripheral (muscle spindle and nerve axon) and central (spinal synapse) components involved in adaptation to calf muscle unloading, it may be used to provide feedback on the general condition of neuromuscular function, and might be used to evaluate the effectiveness of countermeasures aimed at preserving muscle mass and function during periods of unloading. Stretch reflexes were measured on 18 control subjects who spent 60 to 90 days in continuous 6 deg head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 degrees at a peak velocity of about 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender. Computerized posturography was also conducted on these same subjects before and after bed rest as part of the standard measures. Peak-to-peak sway was measured during Sensory Organization Tests (SOTs) to evaluate changes in the ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Although no gender differences were found, a significant increase in reflex latency and a significant decrease in CV were observed during the bed

  17. Strength and conductivity of unidirectional copper composites reinforced by continuous SiC fibers

    Science.gov (United States)

    Kimmig, S.; Allen, I.; You, J. H.

    2013-09-01

    A SiC long fiber-reinforced copper composite offers a beneficial combination of high strength and high thermal conductivity at elevated temperatures. Both properties make the composite a promising material for the heat sink of high-heat-flux components. In this work, we developed a novel Cu/SiCf composite using the Sigma fiber. Based on HIP technique, a metallurgical process was established for fabricating high quality specimens using a TiC interface coating. Extensive tensile tests were conducted on the unidirectionally reinforced composite at 20 °C and 300 °C for a wide range of fiber volume fraction (Vf). In this paper, a large amount of test data is presented. The transversal thermal conductivity varies from 260 to 130 W/mK at 500 °C as Vf is increased from 13% to 37%. The tensile strength reached up to 1246 MPa at 20 °C for Vf = 37.6%, where the fracture strain was limited to 0.8%. The data of both elastic modulus and ultimate strength exhibited a good agreement with the rule-of-mixture predictions indicating a high quality of the materials. The strength of the composite with the Sigma fibers turned out to be superior to those of the SCS6 fibers at 300 °C, although the SCS6 fiber actually has a higher strength than the Sigma fiber. The fractographic pictures of tension test and fiber push-out test manifested a sufficient interfacial bonding. Unidirectional copper composite reinforced by long SiC fibers was fabricated using the Sigma SM1140+ fiber for a wide range of fiber volume fraction from 14% to 40%. Extensive tensile tests were carried out at RT and 300 °C. The data of ultimate strength as well as elastic modulus exhibited a good agreement with the rule-of-mixture predictions indicating a high quality of the materials. In terms of the tensile strength, the Cu/Sigma composite turned out to be superior to the previous Cu/SCS6 composite at 300 °C, while comparable at RT, although the SCS6 fiber has a higher strength than the Sigma fiber. Such a

  18. Easy Method to Examine Single Nerve Fiber Excitability and Conduction Parameters Using Intact Nonanesthetized Earthworms

    Science.gov (United States)

    Bähring, Robert; Bauer, Christiane K.

    2014-01-01

    The generation and conduction of neuronal action potentials (APs) were the subjects of a cell physiology exercise for first-year medical students. In this activity, students demonstrated the all-or-none nature of AP generation, measured conduction velocity, and examined the dependence of the threshold stimulus amplitude on stimulus duration. For…

  19. Fabrication and Characterization of Conductive Conjugated Polymer-Coated Antheraea mylitta Silk Fibroin Fibers for Biomedical Applications.

    Science.gov (United States)

    Gh, Darshan; Kong, Dexu; Gautrot, Julien; Vootla, Shyam Kumar

    2017-02-27

    Conductive polymers are interesting materials for a number of biological and medical applications requiring electrical stimulation of cells or tissues. Highly conductive polymers (polypyrrole and polyaniline)/Antheraea mylitta silk fibroin coated fibers are fabricated successfully by in situ polymerization without any modification of the native silk fibroin. Coated fibers characterized by scanning electron microscopy confirm the silk fiber surface is covered by conductive polymers. Thermogravimetric analysis reveals preserved thermal stability of silk fiber after coating process. X-ray diffraction of degummed fiber diffraction peaks at around 2θ = 20.4 and 16.5 confirms the preservation of the β-sheet structure typical of degummed silk II fibers. This phenomenon implies that both polypyrrole and polyaniline chains form interactions with peptide linkages in degummed fiber macromolecules, without significantly disrupting protein assembly. Fourier transform infrared spectroscopy of coated fibers indicates hydrogen bonding and electrostatic interactions exist between silk fibroin macromolecules and conductive polymers. Resulting fibers display good conductive properties compared to corresponding conjugated polymers. In vitro analysis (live/dead assay) of the behavior of human immortalized keratinocytes (HaCaTs) on coated fibers demonstrates improved cell-adhesive properties and viability after polymers coating. Hence, polypyrrole- and polyaniline-coated A. mylitta silk fibers are suitable for application in cell culture and for tissue engineering, where electrical conduction properties are required.

  20. Self-Healing of Ionomeric Polymers with Carbon Fibers from Medium-Velocity Impact and Resistive Heating

    Directory of Open Access Journals (Sweden)

    Vishnu Baba Sundaresan

    2013-01-01

    Full Text Available Self-healing materials science has seen significant advances in the last decade. Recent efforts have demonstrated healing in polymeric materials through chemical reaction, thermal treatment, and ultraviolet irradiation. The existing technology for healing polymeric materials through the aforementioned mechanisms produces an irreversible change in the material and makes it unsuitable for subsequent healing cycles. To overcome these disadvantages, we demonstrate a new composite self-healing material made from an ionomer (Surlyn and carbon fiber that can sustain damage from medium-velocity impact and heal from the energy of the impact. Furthermore, the carbon fiber embedded in the polymer matrix results in resistive heating of the polymer matrix locally, melts the ionomer matrix around the damage, and heals the material at the damaged location. This paper presents methods to melt-process Surlyn with carbon fiber and demonstrates healing in the material through medium-velocity impact tests, resistive heating, and imaging through electron and optical microscopy. A new metric for quantifying self-healing in the sample, called width-heal ratio, is developed, and we report that the Surlyn-carbon fiber-based material under an optimal rate of heating and at the correct temperature has a width-heal ratio of >0.9, thereby demonstrating complete recovery from the damage.

  1. Knitted Strain Sensor Textiles of Highly Conductive All-Polymeric Fibers.

    Science.gov (United States)

    Seyedin, Shayan; Razal, Joselito M; Innis, Peter C; Jeiranikhameneh, Ali; Beirne, Stephen; Wallace, Gordon G

    2015-09-30

    A scaled-up fiber wet-spinning production of electrically conductive and highly stretchable PU/PEDOT:PSS fibers is demonstrated for the first time. The PU/PEDOT:PSS fibers possess the mechanical properties appropriate for knitting various textile structures. The knitted textiles exhibit strain sensing properties that were dependent upon the number of PU/PEDOT:PSS fibers used in knitting. The knitted textiles show sensitivity (as measured by the gauge factor) that increases with the number of PU/PEDOT:PSS fibers deployed. A highly stable sensor response was observed when four PU/PEDOT:PSS fibers were co-knitted with a commercial Spandex yarn. The knitted textile sensor can distinguish different magnitudes of applied strain with cyclically repeatable sensor responses at applied strains of up to 160%. When used in conjunction with a commercial wireless transmitter, the knitted textile responded well to the magnitude of bending deformations, demonstrating potential for remote strain sensing applications. The feasibility of an all-polymeric knitted textile wearable strain sensor was demonstrated in a knee sleeve prototype with application in personal training and rehabilitation following injury.

  2. Low-Cost Timer to Measure the Terminal Velocity of a Magnet Falling through a Conducting Pipe

    Science.gov (United States)

    Pathare, Shirish R.; Huli, Saurabhee; Lahane, Rohan; Sawant, Sumedh

    2014-01-01

    Dropping a magnet into a conductive pipe (made up of copper or brass or aluminum) is a very popular demonstration in many physics classrooms and laboratories. In this paper we present an inexpensive timer that can be used to measure the terminal velocity of the magnet falling through a conducting pipe. The timer assembly consists of Hall effect…

  3. Low-Cost Timer to Measure the Terminal Velocity of a Magnet Falling through a Conducting Pipe

    Science.gov (United States)

    Pathare, Shirish R.; Huli, Saurabhee; Lahane, Rohan; Sawant, Sumedh

    2014-01-01

    Dropping a magnet into a conductive pipe (made up of copper or brass or aluminum) is a very popular demonstration in many physics classrooms and laboratories. In this paper we present an inexpensive timer that can be used to measure the terminal velocity of the magnet falling through a conducting pipe. The timer assembly consists of Hall effect…

  4. Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

    Science.gov (United States)

    Ma, Pei; Wang, Yves T.; Gu, Shi; Watanabe, Michiko; Jenkins, Michael W.; Rollins, Andrew M.

    2014-07-01

    Optical mapping (OM) of cardiac electrical activity conventionally collects information from a three-dimensional (3-D) surface as a two-dimensional (2-D) projection map. When applied to measurements of the embryonic heart, this method ignores the substantial and complex curvature of the heart surface, resulting in significant errors when calculating conduction velocity, an important electrophysiological parameter. Optical coherence tomography (OCT) is capable of imaging the 3-D structure of the embryonic heart and accurately characterizing the surface topology. We demonstrate an integrated OCT/OM imaging system capable of simultaneous conduction mapping and 3-D structural imaging. From these multimodal data, we obtained 3-D activation maps and corrected conduction velocity maps of early embryonic quail hearts. 3-D correction eliminates underestimation bias in 2-D conduction velocity measurements, therefore enabling more accurate measurements with less experimental variability. The integrated system will also open the door to correlate the structure and electrophysiology, thereby improving our understanding of heart development.

  5. Effect of chronic renal failure, dialysis and transplantation on motor nerve conduction velocity in children.

    Science.gov (United States)

    Arbus, G. S.; Barnor, N. A.; Hsu, A. C.; Murphy, E. G.; Radde, I. C.

    1975-01-01

    Ulnar and peroneal motor nerve conduction volocities (MNCVs) were measured in 47 children in a dialysis-transplantation program. Mean peroneal MNCV was significantly decreased from normal in children with mild renal failure (serum creatinine concentration, 1.5 to 2.9 mg/dl), whereas ulnar MNCV was significantly decreased only when the serum creatinine value was at least 9 mg/dl. Both ulnar and peroneal MNCVs remained unchanged during long-term hemodialysis or peritoneal dialysis; however, after individual dialyses ulnar MNCV increased. After renal transplantation ulnar MNCV returned to normal within a year and peroneal MNCV within 3 years. Before dialysis was required and during long-term dialysis most plasma magnesium values were elevated; ionized calcium activity was decreased in about 50% of determinations. After transplantation and the concentration of divalent cations rapidly returned to normal. These children differed from adults studied in that (a) there was no correlation between severity of renal failure and MNCV, (b) long-term dialysis did not improve MNCV and (c) peroneal velocities did not recover for 3 years after transplantation. PMID:1098759

  6. Ionic mechanisms maintaining action potential conduction velocity at high firing frequencies in an unmyelinated axon.

    Science.gov (United States)

    Cross, Kevin P; Robertson, R Meldrum

    2016-05-01

    The descending contralateral movement detector (DCMD) is a high-performance interneuron in locusts with an axon capable of transmitting action potentials (AP) at more than 500 Hz. We investigated biophysical mechanisms for fidelity of high-frequency transmission in this axon. We measured conduction velocities (CVs) at room temperature during exposure to 10 mmol/L cadmium, a calcium current antagonist, and found significant reduction in CV with reduction at frequencies >200 Hz of ~10%. Higher temperatures induced greater CV reductions during exposure to cadmium across all frequencies of ~20-30%. Intracellular recordings during 15 min of exposure to cadmium or nickel, also a calcium current antagonist, revealed an increase in the magnitude of the afterhyperpolarization potential (AHP) and the time to recover to baseline after the AHP (Medians for Control: -19.8%; Nickel: 167.2%; Cadmium: 387.2%), that could be due to a T-type calcium current. However, the removal of extracellular calcium did not mimic divalent cation exposure suggesting calcium currents are not the cause of the AHP increase. Computational modeling showed that the effects of the divalent cations could be modeled with a persistent sodium current which could be blocked by high concentrations of divalent cations. Persistent sodium current shortened the AHP duration in our models and increased CV for high-frequency APs. We suggest that faithful, high-frequency axonal conduction in the DCMD is enabled by a mechanism that shortens the AHP duration like a persistent or resurgent sodium current.

  7. Electrospun carbon nanofibers for improved electrical conductivity of fiber reinforced composites

    Science.gov (United States)

    Alarifi, Ibrahim M.; Alharbi, Abdulaziz; Khan, Waseem S.; Asmatulu, Ramazan

    2015-04-01

    Polyacrylonitrile (PAN) was dissolved in dimethylformamide (DMF), and then electrospun to generate nanofibers using various electrospinning conditions, such as pump speeds, DC voltages and tip-to-collector distances. The produced nanofibers were oxidized at 270 °C for 1 hr, and then carbonized at 850 °C in an argon gas for additional 1 hr. The resultant carbonized PAN nanofibers were placed on top of the pre-preg carbon fiber composites as top layers prior to the vacuum oven curing following the pre-preg composite curing procedures. The major purpose of this study is to determine if the carbonized nanofibers on the fiber reinforced composites can detect the structural defects on the composite, which may be useful for the structural health monitoring (SHM) of the composites. Scanning electron microscopy images showed that the electrospun PAN fibers were well integrated on the pre-preg composites. Electrical conductivity studies under various tensile loads revealed that nanoscale carbon fibers on the fiber reinforced composites detected small changes of loads by changing the resistance values. Electrically conductive composite manufacturing can have huge benefits over the conventional composites primarily used for the military and civilian aircraft and wind turbine blades.

  8. RESEARCH ON THE THERMAL CONDUCTIVITY OF COMPOSITES MADE OF ECOLOGICAL FIBERS

    Directory of Open Access Journals (Sweden)

    Maria-Luminita BRENCI, Camelia COSEREANU, Adriana FOTIN, Alexandru VASILACHE

    2013-09-01

    Full Text Available The paper presents the results of the researchconducted to obtain new ecological composites thatcould be used for thermal insulation of buildings. Theobtained panels are made of ecological materials thatdo not affect the human health (wood chips andfibers, host of hemp, textile fibers, wool and reed.The testing was performed in eight points, for aninternal temperature of T=200C and an outdoortemperature situated in the range of -200C÷200C. Asthe tests conducted, the results showed that the bestinsulating capacity belonged to a composite whichhas wood fiber and wool in its structure, followed acomposite which has wood chips, hemp particles andwool in its structure.

  9. [The influence of frequency and blockade of the autonomic nervous system on the functional behaviour of the human conduction system. Part A: Conduction velocity (author's transl)].

    Science.gov (United States)

    Runge, M; Luckmann, E; Narula, O S

    1976-01-01

    32 patients were studied by His-bundle recordings to examine the extent to which frequency and autonomic nervous system influence the conduction velocity in the subdivisions (atrium, AV-node, His-Purkinje system) of the normal PR-interval. The measurements were performed during sinus rhythm and three electrically induced atrial frequencies before and after intravenous administration of 1 mg Atropine (15 patients) and 0.4 mg Visken (17 patients). In influencing the atrial conduction velocity frequency dominates the blockade of both components of the autonomic nervous system. Increase in frequency lengthens the intraatrial conduction time. Blockade of parasympathicus and sympathicus does not significantly influence the changes in intraatrial conduction velocity induced by increase of frequency. Patients with prolonged intraatrial conduction respond in the same way to cycle length shortening and blockade of the autonomic tone as patients with normal conduction. The results are discussed with respect to acetylcholine and catecholamine influence on the electrophysiological properties of the atrial myocardium. The AV-node is the part of the conduction system most sensitive to the influence of both cycle length shortening and blockade of the autonomic nervous system. Artificially induced cycle length shortening prolongs the intranodal conduction time to a different individual level for each patient. Blockade of the parasympathicus not only shortens this interval but also reduces the steepness of the AH-time induced by atrial pacing. Blockade of the sympathicus has the opposite effect. The most likely explanation for these results is the abolishing of the functional dissociation within the AV-node by blocking the autonomic influence on this structure. The conduction velocity in the His-Purkinje system is influenced neither by atrial pacing nor by blockade of both components of the autonomic nervous system.

  10. Effects of group-velocity mismatch and cubicquintic nonlinearity on cross-phase modulation instability in optical fibers

    Institute of Scientific and Technical Information of China (English)

    Xianqiong Zhong; Anping Xiang

    2007-01-01

    @@ The synthetic effects of group-velocity mismatch and cubic-quintic nonlinearity on cross-phase modulation induced modulation instability in loss single-mode optical fibers have been numerically investigated. The results show that the quintic nonlinearity plays a role similar to the case of neglecting the group-velocity mismatch in modifying the modulation instability, namely, the positive and negative quintic nonlinearities can still enhance and weaken the modulation instability, respectively. The group-velocity mismatch can considerably change the gain spectrum of modulation instability in terms of its shape, peak value, and position. In the normal dispersion regime, with the increase of the group-velocity mismatch parameter,the gain spectrum widens and then narrows, shifts to higher frequencies, and the peak value gets higher before approaching a saturable value. In the abnormal dispersion regime, two separated spectra may occur when the group-velocity mismatch is taken into account. With the increase of the group-velocity mismatch parameter, the peak value of the gain spectrum gets higher and shorter before tending to a saturable value for the first and second spectral regimes, respectively.

  11. “MODAL NOISE” IN SINGLE-MODE FIBERS: A CAUTIONARY NOTE FOR HIGH PRECISION RADIAL VELOCITY INSTRUMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Schwab, Christian, E-mail: shalverson@psu.edu [Macquarie University, Sydney, NSW 2109 (Australia)

    2015-12-01

    Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical “seeing-limited” instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as “modal noise,” are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, SMFs do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading illumination stability. Here we present a cautionary note outlining how the polarization properties of SMFs can affect the radial velocity (RV) measurement precision of high resolution spectrographs. This work is immediately relevant to the rapidly expanding field of diffraction-limited, extreme precision RV spectrographs that are currently being designed and built by a number of groups.

  12. ELECTRICAL CONDUCTIVITY OF IODINE DOPED POLY(PHTHALOCYANINATOSILOXANE)/PPTA BLEND FIBERS

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao; J.W.Lyding; T.J.Marks; S.H.Carr

    1988-01-01

    Poly(phthalocyaninatosiloxane), [Si(Pc)O]n, with the number average degree of polymerization of about 130 was prepared by heating its monomer Si(Pc) (OH)2, in solid state at 420℃ for 42 hrs at 10-3 torr dynamic vacuum. The [Si(Pc)O]n powder was iodine doped with I2-benzene solution for 48 hrs. Pure iodine doped poly(phthalocyaninatosiloxane), {[Si(Pc)O]Iy}n, fibers and {[Si(Pc)O]Iy}n/poly(p-phenylene terephthalamide) blend fibers were wet-spun with dry nitrogen-sealed Teflon lined device. D.C. electrical conductivity of the fibers was measured by the four-probe method with an automated charge transport measurement system from 80K to room temperature. It was found that the dependence of conductivity, σ, on temperature, T, could fit a group of thermal fluctuation-induced tunnelling (TFIT) equations, and that the dependence of conductivity on volume fraction, ψ, of the iodine doped {[Si(Pc)O]Iy}n could fit a group of modified percolation equations. A three-dimensional composite plot of σ-1/T-ψ shows that these two groups of equations match each other quite well. It has been pointed out that for the blend fibers their composition is the most important factor for both mechanieal and electrical properties.

  13. Conductively cooled high-power high-brightness bars and fiber-coupled arrays

    Science.gov (United States)

    Zhou, Hailong; Mondry, Mark; Fouksman, Michael; Weiss, Eli; Anikitchev, Serguei; Kennedy, Keith; Li, Jun; Zucker, Erik; Rudy, Paul; Kongas, Jukka; Haapamaa, Jouko; Lehkonen, Sami

    2005-03-01

    Solid-state-laser and fiber laser pumping, reprographics, medical and materials processing applications require high power, high-brightness bars and fiber-coupled arrays. Conductively cooled laser diode bars allow customers to simplify system design and reduce operational size, weight, and costs. We present results on next generation high brightness, high reliability bars and fiber-coupled arrays at 790-830 nm, 940 nm and 980 nm wavelengths. By using novel epitaxial structures, we have demonstrated highly reliable 808 nm, 30% fill-factor conductively cooled bars operating at 60W CW mode, corresponding to a linear power density (LPD) of 20 mW/&mum. At 25°C, the bars have shown greater than 50% wall-plug-efficiency (WPE) when operating at 60W. Our novel approach has also reduced the fast-axis divergence FWHM from 31° to less than 24°. These bars have a 50% brightness improvement compared to our standard products with this geometry. At 980nm, we have demonstrated greater than 100W CW from 20% fill-factor conductively cooled bars, corresponding to a LPD of 50 mW/μm. At 25°C, the WPE for 976nm bars consistently peaks above 65% and remains greater than 60% at 100W. We coupled the beam output from those high-brightness bars into fiber-array-packages ("FAPs"), and we also achieved high-brightness and high-efficiency FAPs. We demonstrated 60W from a 600μm core-diameter fiber-bundle with a high WPE of 55%, and a low numerical aperture of 0.115. The brightness of such FAPs is four times higher than our standard high-power 40W FAP products at Coherent. Ongoing life test data suggests an extrapolated lifetime greater than 10,000 hours at 80W CW operating-condition based on 30%FF conductively cooled bar geometry.

  14. Network model for thermal conductivities of unidirectional fiber-reinforced composites

    Science.gov (United States)

    Wang, Yang; Peng, Chaoyi; Zhang, Weihua

    2014-12-01

    An empirical network model has been developed to predict the in-plane thermal conductivities along arbitrary directions for unidirectional fiber-reinforced composites lamina. Measurements of thermal conductivities along different orientations were carried out. Good agreement was observed between values predicted by the network model and the experimental data; compared with the established analytical models, the newly proposed network model could give values with higher precision. Therefore, this network model is helpful to get a wider and more comprehensive understanding of heat transmission characteristics of fiber-reinforced composites and can be utilized as guidance to design and fabricate laminated composites with specific directional or specific locational thermal conductivities for structures that simultaneously perform mechanical and thermal functions, i.e. multifunctional structures (MFS).

  15. Highly conductive and flexible nylon-6 nonwoven fiber mats formed using tungsten atomic layer deposition.

    Science.gov (United States)

    Kalanyan, Berç; Oldham, Christopher J; Sweet, William J; Parsons, Gregory N

    2013-06-12

    Low-temperature vapor-phase tungsten atomic layer deposition (ALD) using WF6 and dilute silane (SiH4, 2% in Ar) can yield highly conductive coatings on nylon-6 microfiber mats, producing flexible and supple nonwovens with conductivity of ∼1000 S/cm. We find that an alumina nucleation layer, reactant exposure, and deposition temperature all influence the rate of W mass uptake on 3D fibers, and film growth rate is calibrated using high surface area anodic aluminum oxide. Transmission electron microscopy (TEM) reveals highly conformal tungsten coatings on nylon fibers with complex "winged" cross-section. Using reactant gas "hold" sequences during the ALD process, we conclude that reactant species can transport readily to reactive sites throughout the fiber mat, consistent with conformal uniform coverage observed by TEM. The conductivity of 1000 S/cm for the W-coated nylon is much larger than found in other conductive nonwovens. We also find that the nylon mats maintain 90% of their conductivity after being flexed around cylinders with radii as small as 0.3 cm. Metal ALD coatings on nonwovens make possible the solvent-free functionalization of textiles for electronic applications.

  16. The experimental studies on electrical conductivities and P-wave velocities of anorthosite at high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    白利平; 杜建国; 刘巍; 周文戈

    2002-01-01

    Results of P-wave velocity (vP) and electrical conductivity measurements on anorthosite are presented from room temperature to 880 (C at 1.0 GPa using ultrasonic transmission technique and impedance spectra technique respectively. The experiments show that the P-wave velocities in anorthosite decrease markedly above 680 (C following the dehydration of hydrous minerals in the rock, and the complex impedances collected from 12 Hz to 105 Hz only indicate the grain interior conduction mechanism at 1.0 GPa, from 410 (C to 750 (C. Because the fluids in the rock have not formed an interconnected network, the dehydration will not pronouncedly enhance the electrical conductivity and change the electrical conduction mechanism. It is concluded that the formation and evolution of the low-velocity zones and high-conductivity layers in the crust may have no correlations, and the dehydration can result in the formation of the low-velocity zones, but cannot simultaneously result in the high-conductivity layers.

  17. Simultaneous measurement of thermal conductivity and thermal contact resistance of individual carbon fibers using Raman spectroscopy.

    Science.gov (United States)

    Liu, Jinhui; Wang, Haidong; Ma, Weigang; Zhang, Xing; Song, Yan

    2013-04-01

    In this paper, a new method employing Raman spectroscopy to determine thermal conductivity (TC) and thermal contact resistance (TCR) of an individual fiber was developed. Laser absorption is accounted for, but there is no need to be determined in this method. The local temperatures along the fiber longitudinal direction were determined by Raman shift. Two independent equations related to TC and TCR were established through measuring the temperature variation induced by changing electrical heating power at the center of the sample and the local temperature rise induced by a focused laser heating from Raman spectroscopy at two different positions on the sample, respectively. By solving the two equations, TC and TCR can then be obtained. This method has been validated by measuring two suspended carbon fibers.

  18. Two measurement methods of motor ulnar nerve conduction velocity at the elbow: A comparative study

    Directory of Open Access Journals (Sweden)

    Azma K

    2007-01-01

    Full Text Available Background: Electrodiagnostically, localization of ulnar nerve lesions, which commonly occurs at the elbow, is sometimes problematic. Measurement of motor ulnar nerve conduction velocity (NCV at the elbow is amongst the most popular techniques to diagnose ulnar neuropathy. In this method, recording from the first dorsal interosseous muscle (FDI is suggested to be more sensitive than the abductor digiti minimi (ADM. However, the criterion for abnormality is based on the normal values recorded from ADM. Aims: To determine the normal values of Ulnar motor NCV using FDI and ADM and the difference between the values obtained from FDI and ADM. Additionally, to measure the amount of reduction of NCV across the elbow for each recording site. Materials and Methods: This was a cross-sectional study performed on 50 healthy volunteers (100 nerves. All subjects were in the same condition regarding joint position and surface hand temperature. We recorded ulnar NCV at forearm and across the elbow with recording electrode on both FDI and ADM, simultaneously. Results and Conclusions: The mean NCV at the elbow recorded from ADM and FDI were 62.65 ± 7.62 m/s and 60.49 ± 7.42 m/s respectively, showing significant difference. The ulnar minimum normal NCVs recorded from ADM and FDI were 47.4 m/s and 45.6 m/s, respectively. If the normal values of ADM are used as the basis for recording from FDI, it could lead to false-positive diagnosis of cases suspicious of ulnar neuropathy. Therefore it is preferred to use the normal values of FDI itself while recording.

  19. The thermal conductivity of high modulus Zylon fibers between 400 mK and 4 K

    Science.gov (United States)

    Wikus, Patrick; Figueroa-Feliciano, Enectalí; Hertel, Scott A.; Leman, Steven W.; McCarthy, Kevin A.; Rutherford, John M.

    2008-11-01

    Zylon is a synthetic polyurethane polymer fiber featuring very high mechanical strength. Measurements of the thermal conductivity λZ(T) of high modulus Zylon fibers at temperatures between 400 mK and 4 K were performed to assess if they can be successfully employed in the design of high performance suspension systems for cold stages of adiabatic demagnetization refrigerators. The linear mass density of the yarn used in these measurements amounts to 3270 dtex, which is also a measure for the yarn's cross section. The experimental data for the thermal conductivity was fitted to a function of the form λZ=(1010±30)·TpWmmdtexK. This result was normalized to the breaking strength of the fibers and compared with Kevlar. It shows that Kevlar outperforms Zylon in the investigated temperature range. At 1.5 K, the thermal conductivity integral of Zylon yarn is twice as high as the thermal conductivity integral of Kevlar yarn with the same breaking strength. A linear mass density of 1 tex is equivalent to a yarn mass of 1 g/km. High modulus Zylon has a density of 1.56 g/cm 3.

  20. SURFACE EMG AND MUSCLE-FIBER CONDUCTION DURING ATTACKS OF HYPOKALEMIC PERIODIC PARALYSIS

    NARCIS (Netherlands)

    LINKS, TP; VANDERHOEVEN, JH; ZWARTS, MJ

    1994-01-01

    Surface EMG, muscle fibre conduction velocity (MFCV), muscle force, and biochemical variables were investigated in a 13-year-old boy with familial hypokalaemic periodic paralysis during and after three attacks of paralysis. After normalisation of the serum potassium values, strength rapidly returned

  1. SURFACE EMG AND MUSCLE-FIBER CONDUCTION DURING ATTACKS OF HYPOKALEMIC PERIODIC PARALYSIS

    NARCIS (Netherlands)

    LINKS, TP; VANDERHOEVEN, JH; ZWARTS, MJ

    1994-01-01

    Surface EMG, muscle fibre conduction velocity (MFCV), muscle force, and biochemical variables were investigated in a 13-year-old boy with familial hypokalaemic periodic paralysis during and after three attacks of paralysis. After normalisation of the serum potassium values, strength rapidly returned

  2. Experimental Study on Deicing Performance of Carbon Fiber Reinforced Conductive Concrete

    Institute of Scientific and Technical Information of China (English)

    Zuquan TANG; Zhuoqiu LI; Jueshi QIAN; Kejin WANG

    2005-01-01

    Carbon fiber reinforced concrete (CFRC) is a kind of good electrothermal material. When connected to an external power supply, stable and uniform heat suitable for deicing application is generated in the CFRC slab. Electric heating and deicing experiments of carbon fiber reinforced concrete slab were carried out in laboratory, and the effect of the temperature and thickness of ice, the thermal conductivity of CFRC, and power output on deicing performance and energy consumption were investigated. The experimental results indicate that it is an effective method to utilize the thermal energy produced by CFRC slab to deice. The time to melt the ice completely decreases with increasing power output and ice temperature, and increases with increasing thickness of the ice. The energy consumption to ranges from -3℃ to -18℃. CFRC with good thermal conduction can reduce temperature difference in CFRC slab effectively.

  3. Coefficient of Friction Measurements for Thermoplastics and Fiber Composites under Low Sliding Velocity and High Pressure

    DEFF Research Database (Denmark)

    Poulios, Konstantinos; Svendsen, G.; Hiller, Jochen

    2012-01-01

    materials which are untypical for brake applications, like thermoplastics and fiber composites, can offer superior performance in terms of braking torque, wear resistance and cost than typical brake linings. In this paper coefficient of friction measurements for various thermoplastic and fiber composite...... materials running against a steel surface are presented. All tests were carried out on a pin-on-disc test-rig at a fixed sliding speed and various pressure levels for both dry and grease lubricated conditions....

  4. Long-period fiber grating sensors for the measurement of liquid level and fluid-flow velocity.

    Science.gov (United States)

    Wang, Jian-Neng; Luo, Ching-Ying

    2012-01-01

    This paper presents the development and assessment of two types of Long Period Fiber Grating (LPFG)-based sensors including a mobile liquid level sensor and a reflective sensor for the measurement of liquid level and fluid-flow velocity. Shewhart control charts were used to assess the liquid level sensing capacity and reliability of the mobile CO(2)-laser engraved LPFG sensor. There were ten groups of different liquid level experiment and each group underwent ten repeated wavelength shift measurements. The results showed that all measurands were within the control limits; thus, this mobile sensor was reliable and exhibited at least 100-cm liquid level measurement capacity. In addition, a reflective sensor consisting of five LPFGs in series with a reflective end has been developed to evaluate the liquid level and fluid-flow velocity. These five LPFGs were fabricated by the electrical arc discharge method and the reflective end was coated with silver by Tollen's test. After each liquid level experiment was performed five times, the average values of the resonance wavelength shifts for LPFG Nos. 1-5 were in the range of 1.35-9.14 nm. The experimental findings showed that the reflective sensor could be used to automatically monitor five fixed liquid levels. This reflective sensor also exhibited at least 100-cm liquid level measurement capacity. The mechanism of the fluid-flow velocity sensor was based on analyzing the relationship among the optical power, time, and the LPFG's length. There were two types of fluid-flow velocity measurements: inflow and drainage processes. The differences between the LPFG-based fluid-flow velocities and the measured average fluid-flow velocities were found in the range of 8.7-12.6%. For the first time to our knowledge, we have demonstrated the feasibility of liquid level and fluid-flow velocity sensing with a reflective LPFG-based sensor without modifying LPFGs or coating chemical compounds.

  5. On the Estimation of Muscle Fiber Conduction Velocity Using a Co-Linear Electrodes Array

    Science.gov (United States)

    2007-11-02

    an important parameter of the myoelectric signal which describes muscle fatigue manifestation during voluntary or elicited contractions. It may...Surface Myoelectric Signals Part I: Model Implementation”, IEEE Trans. on BME, Vol. 46, No. 7, pp. 810-820, 1999 [6] W. Muhammad, “Estimation de retards...optimal method to estimate the TD is the Generalized Cross- Correlation method (GCC), but this requires a priori knowledge about signal and noise. In

  6. MUSCLE-FIBER CONDUCTION-VELOCITY IN THE DIAGNOSIS OF SPORADIC HYPOKALEMIC PERIODIC PARALYSIS

    NARCIS (Netherlands)

    BROUWER, OF; ZWARTS, MJ; LINKS, TP; WINTZEN, AR

    1992-01-01

    A 6-year-old girl presented with episodes of profound muscle weakness since the age of 2 years. On the basis of decreased ictal serum potassium level and lack of metabolic disorder, primary hypokalemic periodic paralysis (HPP) was diagnosed. Both parents and 3 sibs were unaffected clinically. In all

  7. MUSCLE-FIBER CONDUCTION-VELOCITY IN THE DIAGNOSIS OF SPORADIC HYPOKALEMIC PERIODIC PARALYSIS

    NARCIS (Netherlands)

    BROUWER, OF; ZWARTS, MJ; LINKS, TP; WINTZEN, AR

    1992-01-01

    A 6-year-old girl presented with episodes of profound muscle weakness since the age of 2 years. On the basis of decreased ictal serum potassium level and lack of metabolic disorder, primary hypokalemic periodic paralysis (HPP) was diagnosed. Both parents and 3 sibs were unaffected clinically. In all

  8. Conductive fiber-based ultrasensitive textile pressure sensor for wearable electronics.

    Science.gov (United States)

    Lee, Jaehong; Kwon, Hyukho; Seo, Jungmok; Shin, Sera; Koo, Ja Hoon; Pang, Changhyun; Son, Seungbae; Kim, Jae Hyung; Jang, Yong Hoon; Kim, Dae Eun; Lee, Taeyoon

    2015-04-17

    A flexible and sensitive textile-based pressure sensor is developed using highly conductive fibers coated with dielectric rubber materials. The pressure sensor exhibits superior sensitivity, very fast response time, and high stability, compared with previous textile-based pressure sensors. By using a weaving method, the pressure sensor can be applied to make smart gloves and clothes that can control machines wirelessly as human-machine interfaces.

  9. Fabrication and Protein Conjugation of Aligned Polypyrrole-Poly(L-lactic acid) Fibers Film with the Conductivity and Stability.

    Science.gov (United States)

    Qin, Jiabang; Huang, Zhongbing; Yin, Guangfu; Yang, Anneng; Han, Wei

    2016-03-01

    The conducting composite scaffold, including fiber-cores of aligned poly(L-lactic acid) (PLLA) and shell-layer of polypyrrole (PPy), was fabricated, and then bovine serum albumin (BSA) was conjugated on the PPy shell-layer. Aligned PLLA fibers (about 300 nm diameter) were obtained by electrospinning and rotating drum collection, and then coated by PPy nanoparticles (NPs, about 50 nm diameter) via chemical oxidation. The surface resistivity of PPy-PLLA fibers film were 0.971, 0.874 kΩ. cm at the fiber's vertical and parallel directions, respectively. The results of PPy-PLLA fibers film immersed in phosphate buffer saline for 8 d indicated that the fibers morphology and the film conductivity were not significantly changed, and the fluorescent images showed that FITC-labeled BSA (FITC-BSA) were successfully conjugated in the fibers film with carbodiimide chemistry, and the largest amount of FITC-BSA conjugated in the fibers film from 100 μg/mL proteins solution was 31.31 μg/cm2 due to lots of poly(glutamic acid) in surface-nanogrooves of the fibers surface. Under electrical stimulation of 100 mV, the fibers film was accompanied the release of all conjugated FITC-BSA with the detachment of some PPy NPs. These results suggested that PPy-PLLA fibers film would be potentially applied in the construction of degradable tissue engineering scaffold with protein factors, especially neurotrophic factors for nerve tissue repair.

  10. Fiber-Based Doppler Lidar for Vector Velocity and Altitude Measurements

    Science.gov (United States)

    Amzajerdian, Farzin; Pierrottet, Diego; Hines, Glenn; Petway, Larry; Barnes, Bruce

    2015-01-01

    A coherent Doppler lidar capable of providing accurate velocity and altitude data has been developed and demonstrated for future NASA missions to the solar system bodies requiring precision navigation and controlled soft landing.

  11. Tuning quadratic nonlinear photonic crystal fibers for zero group-velocity mismatch

    DEFF Research Database (Denmark)

    Bache, Morten; Lægsgaard, Jesper; Bang, Ole

    2006-01-01

    A nonlinear index-guiding silica PCF is optimized for efficient second-harmonic generation through dispersion calculations. Zero group-velocity mismatch is possible for any pump wavelength above 780 nm. Very high conversion efficiencies and bandwidths are found.......A nonlinear index-guiding silica PCF is optimized for efficient second-harmonic generation through dispersion calculations. Zero group-velocity mismatch is possible for any pump wavelength above 780 nm. Very high conversion efficiencies and bandwidths are found....

  12. Enhanced adhesion and proliferation of human umbilical vein endothelial cells on conductive PANI-PCL fiber scaffold by electrical stimulation.

    Science.gov (United States)

    Li, Yumei; Li, Xiang; Zhao, Rui; Wang, Chuying; Qiu, Fangping; Sun, Bolun; Ji, He; Qiu, Ju; Wang, Ce

    2017-03-01

    Recently, electrically conductive biomaterial scaffolds have shown great potential in tissue regeneration. Herein, we reported an electrically conductive polyaniline (PANI) coated poly(ε-caprolactone) (PCL) electrospun micron-fiber scaffold for the enhanced attachment and proliferation of human umbilical vein endothelial cells (HUVECs) under electrical stimulation conditions. After the O2 plasma treatment toward PCL electrospun fiber, PANI could be polymerized onto their surfaces successfully. The obtained PANI-PCL fibers were characterized by SEM observations, FT-IR spectra, XPS analysis, and water contact angle measurement. The mechanical tests indicated that the fibers could satisfy the practical vascular scaffold requirements. The conductivity of the PANI-PCL fibers was 6.71×10(-3)S/cm which could provide a conductive in-vitro platform to study the effect of electrical stimulation on HUVECs proliferation. When PANI-coated PCL fibers were compared with PCL fibers, HUVECs exhibited highly enhanced adhesion and viability, especially under electrical stimulation (ES) of 200, 300, and 400mV/cm. Proliferation of HUVECs on PANI-PCL fibers was strongly dependent on electrical stimulation intensity. The results showed new insights into conductive scaffolds for vascular tissue engineering. Copyright © 2016. Published by Elsevier B.V.

  13. Evolution of the health of concrete structures by electrically conductive GFRP (glass fiber reinforced plastic) composites

    Science.gov (United States)

    Shin, Soon-Gi

    2002-02-01

    The function and performance of self-diagnostic composites embedded in concrete blocks and piles were investigated by bending tests and electrical resistance measurement. Carbon powder (CP) and carbon fiber (CF) were introduced into glass fiber reinforced plastic (GFRP) composites to provide electrical conductivity. The CPGFRP composite displays generally good performance in various bending tests of concrete block and piles compared to the CFGFRP composite. The electrical resistance of the CPGFRP composite increases remarkably at small strains in response to microcrack formation at about 200 μm strain, and can be used to detect smaller deformations before crack formation. The CPGFRP composite shows continuous change in resistance up to a large strain level just before the final fracture for concrete structures reinforced by steel bars. It is concluded that self-diagnostic composites can be used to predict damage and fracture in concrete blocks and piles.

  14. Velocity and attenuation of shear waves in the phantom of a muscle-soft tissue matrix with embedded stretched fibers

    Science.gov (United States)

    Rudenko, O. V.; Tsyuryupa, S. N.; Sarvazyan, A. P.

    2016-09-01

    We develop a theory of the elasticity moduli and dissipative properties of a composite material: a phantom simulating muscle tissue anisotropy. The model used in the experiments was made of a waterlike polymer with embedded elastic filaments imitating muscle fiber. In contrast to the earlier developed phenomenological theory of the anisotropic properties of muscle tissue, here we obtain the relationship of the moduli with characteristic sizes and moduli making up the composite. We introduce the effective elasticity moduli and viscosity tensor components, which depend on stretching of the fibers. We measure the propagation velocity of shear waves and the shear viscosity of the model for regulated tension. Waves were excited by pulsed radiation pressure generated by modulated focused ultrasound. We show that with increased stretching of fibers imitating muscle contraction, an increase in both elasticity and viscosity takes place, and this effect depends on the wave propagation direction. The results of theoretical and experimental studies support our hypothesis on the protective function of stretched skeletal muscle, which protects bones and joints from trauma.

  15. Polypropylene/Graphene and Polypropylene/Carbon Fiber Conductive Composites: Mechanical, Crystallization and Electromagnetic Properties

    Directory of Open Access Journals (Sweden)

    Chien-Lin Huang

    2015-11-01

    Full Text Available This study aims to examine the properties of composites that different carbon materials with different measurements can reinforce. Using a melt compounding method, this study combines polypropylene (PP and graphene nano-sheets (GNs or carbon fiber (CF to make PP/GNs and PP/CF conductive composites, respectively. The DSC results and optical microscopic observation show that both GNs and CF enable PP to crystalize at a high temperature. The tensile modulus of PP/GNs and PP/CF conductive composites remarkably increases as a result of the increasing content of conductive fillers. The tensile strength of the PP/GNs conductive composites is inversely proportional to the loading level of GNs. Containing 20 wt% of GNs, the PP/GNs conductive composites have an optimal conductivity of 0.36 S/m and an optimal EMI SE of 13 dB. PP/CF conductive composites have an optimal conductivity of 10−6 S/m when composed of no less than 3 wt% of CF, and an optimal EMI SE of 25 dB when composed of 20 wt% of CF.

  16. Wet spinning of continuous polymer-free carbon-nanotube fibers with high electrical conductivity and strength

    Science.gov (United States)

    Mukai, Ken; Asaka, Kinji; Wu, Xueli; Morimoto, Takahiro; Okazaki, Toshiya; Saito, Takeshi; Yumura, Motoo

    2016-05-01

    We report on the fabrication of polymer-free carbon nanotube (CNT) fibers by a novel wet spinning method combined with a very easy and straightforward fabrication process. These fibers exhibited high electrical conductivity (14,284 ± 169 S·cm-1) and tensile strength (887 ± 37 MPa). Such high performance was made possible by the preparation of free-standing CNT fibers from a surfactant solution containing uniformly dispersed CNTs, despite the use of an organic coagulating solvent and subsequent stretching to align the CNTs in the fiber.

  17. Conductive cable fibers with insulating surface prepared by co-axial electrospinning of multi-walled nanotubes and cellulose

    Science.gov (United States)

    Miyauchi, Minoru; Miao, Jianjun; Simmons, Trevor J.; Lee, Jong-Won; Doherty, Thomas V.; Dordick, Jonathan S.; Linhardt, Robert J.

    2010-01-01

    A core-sheath of multi-walled carbon nanotube (MWNT)-cellulose fibers of diameters from several hundreds nm to several µm were prepared by co-axial electrospinning from a non-valatile, non-flammable ionic liquid (IL) solvent, 1-methyl-3-methylimidazolium acetate ([EMIM][Ac]). MWNTs were dispersed in IL to form a gel solution. This gel core solution was electrospun surrounded by a sheath solution of cellulose disolved in the same IL. Electrospun fibers were collected in a coagulation bath containing ethanol-water to completely remove the IL and dried to form a core-sheath MWNT-cellulose fibers having a cable structure with a conductive core and insulating sheath. Enzymatic treatment of a portion of a mat of these fibers with cellulase selectively removed the cellulose sheath exposing the MWNT core for connection to an electrode. These MWNT-cellulose fiber mats demonstrated excellent conductivity due to a conductive pathway of bundleled MWNTs. Fiber mat conductivity increased with increasing ratio of MWNT in the fibers with a maximum conductivity of 10.7 S/m obtained at 45 wt% MWNT loading. PMID:20690644

  18. Collision-free motion planning for fiber positioner robots: discretization of velocity profiles

    CERN Document Server

    Makarem, Laleh; Gillet, Denis; Bleuler, Hannes; Bouri, Mohamed; Hörler, Philipp; Jenni, Laurent; Prada, Francisco; Sanchez, Justo

    2014-01-01

    The next generation of large-scale spectroscopic survey experiments such as DESI, will use thousands of fiber positioner robots packed on a focal plate. In order to maximize the observing time with this robotic system we need to move in parallel the fiber-ends of all positioners from the previous to the next target coordinates. Direct trajectories are not feasible due to collision risks that could undeniably damage the robots and impact the survey operation and performance. We have previously developed a motion planning method based on a novel decentralized navigation function for collision-free coordination of fiber positioners. The navigation function takes into account the configuration of positioners as well as their envelope constraints. The motion planning scheme has linear complexity and short motion duration (~2.5 seconds with the maximum speed of 30 rpm for the positioner), which is independent of the number of positioners. These two key advantages of the decentralization designate the method as a pr...

  19. Long-Period Fiber Grating Sensors for the Measurement of Liquid Level and Fluid-Flow Velocity

    Directory of Open Access Journals (Sweden)

    Jian-Neng Wang

    2012-04-01

    Full Text Available This paper presents the development and assessment of two types of Long Period Fiber Grating (LPFG-based sensors including a mobile liquid level sensor and a reflective sensor for the measurement of liquid level and fluid-flow velocity. Shewhart control charts were used to assess the liquid level sensing capacity and reliability of the mobile CO2-laser engraved LPFG sensor. There were ten groups of different liquid level experiment and each group underwent ten repeated wavelength shift measurements. The results showed that all measurands were within the control limits; thus, this mobile sensor was reliable and exhibited at least 100-cm liquid level measurement capacity. In addition, a reflective sensor consisting of five LPFGs in series with a reflective end has been developed to evaluate the liquid level and fluid-flow velocity. These five LPFGs were fabricated by the electrical arc discharge method and the reflective end was coated with silver by Tollen’s test. After each liquid level experiment was performed five times, the average values of the resonance wavelength shifts for LPFG Nos. 1–5 were in the range of 1.35–9.14 nm. The experimental findings showed that the reflective sensor could be used to automatically monitor five fixed liquid levels. This reflective sensor also exhibited at least 100-cm liquid level measurement capacity. The mechanism of the fluid-flow velocity sensor was based on analyzing the relationship among the optical power, time, and the LPFG’s length. There were two types of fluid-flow velocity measurements: inflow and drainage processes. The differences between the LPFG-based fluid-flow velocities and the measured average fluid-flow velocities were found in the range of 8.7–12.6%. For the first time to our knowledge, we have demonstrated the feasibility of liquid level and fluid-flow velocity sensing with a reflective LPFG-based sensor without modifying LPFGs or coating chemical compounds.

  20. Motor nerve conduction velocity and function in carpal tunnel syndrome following neural mobilization: A randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Manu Goyal

    2016-01-01

    Full Text Available Introduction: Carpal tunnel syndrome (CTS is the most common nerve entrapment syndrome in the upper extremity leading to the functional disability. The consequence of the entrapment is the poor health of the nerve (conduction, mobility, and blood flow. Purpose of the Study: The aim of the study is to evaluate the effect of neural mobilization on the motor nerve conduction velocity and function in the CTS patients. Methods: Thirty CTS patients (only females were scrutinized on the basis of the inclusion and exclusion criteria. They were randomized into two groups A (n = 15 and B (n = 15 using simple random sampling. Group A patients were treated with the conventional physiotherapy regimen and Group B were provided neural mobilization. Results: The data analysis was done using SPSS version 22. The t-test reveals that there was statistically significant improvement in posttreatment values of Group B for numeric pain rating scale, symptom severity scale, function status scale, motor nerve conduction latency, and velocity at P≤ 0.05. Conclusions: Neural mobilization in the CTS patients improves the motor nerve conduction and functional status. It may be incorporated in the physiotherapy treatment protocol of CTS patients.

  1. Super Continuum Generation at 1310nm in a Highly Nonlinear Photonic Crystal Fiber with a Minimum Anomalous Group Velocity Dispersion

    Directory of Open Access Journals (Sweden)

    Ashkan Ghanbari

    2014-12-01

    Full Text Available In the present study, we investigate the evolution of the super continuum generation (SCG through the triangular photonic crystal fiber (PCF at 1310nm by using both full-vector multi pole method (M.P.M and novel concrete algorithms: Symmetric Split-step Fourier (SSF and fourth order Runge Kutta(RK4 which is an accurate method to solve the general nonlinear Schrodinger equation (GNLSE. We propose an ideal solid-core PCF structure featuring a minimum anomalous group velocity dispersion (GVD, small higher order dispersions (HODs and enhanced nonlinearity for appropriate super continuum generation with low input pulse energies over discrete distances of the PCF. We also investigate the impact of the linear and nonlinear effects on the super continuum spectra in detail and compare the results with different status.

  2. Towards seamlessly-integrated textile electronics: methods to coat fabrics and fibers with conducting polymers for electronic applications.

    Science.gov (United States)

    Allison, Linden; Hoxie, Steven; Andrew, Trisha L

    2017-06-29

    Traditional textile materials can be transformed into functional electronic components upon being dyed or coated with films of intrinsically conducting polymers, such as poly(aniline), poly(pyrrole) and poly(3,4-ethylenedioxythiophene). A variety of textile electronic devices are built from the conductive fibers and fabrics thus obtained, including: physiochemical sensors, thermoelectric fibers/fabrics, heated garments, artificial muscles and textile supercapacitors. In all these cases, electrical performance and device ruggedness is determined by the morphology of the conducting polymer active layer on the fiber or fabric substrate. Tremendous variation in active layer morphology can be observed with different coating or dyeing conditions. Here, we summarize various methods used to create fiber- and fabric-based devices and highlight the influence of the coating method on active layer morphology and device stability.

  3. Low temperature platinum atomic layer deposition on nylon-6 for highly conductive and catalytic fiber mats

    Energy Technology Data Exchange (ETDEWEB)

    Mundy, J. Zachary; Shafiefarhood, Arya; Li, Fanxing; Khan, Saad A.; Parsons, Gregory N., E-mail: gnp@ncsu.edu [Department of Chemical and Biomolecular Engineering, North Carolina State University, Engineering Building I, 911 Partners Way, Raleigh, North Carolina 27695-7905 (United States)

    2016-01-15

    Low temperature platinum atomic layer deposition (Pt-ALD) via (methylcyclopentadienyl)trimethyl platinum and ozone (O{sub 3}) is used to produce highly conductive nonwoven nylon-6 (polyamide-6, PA-6) fiber mats, having effective conductivities as high as ∼5500–6000 S/cm with only a 6% fractional increase in mass. The authors show that an alumina ALD nucleation layer deposited at high temperature is required to promote Pt film nucleation and growth on the polymeric substrate. Fractional mass gain scales linearly with Pt-ALD cycle number while effective conductivity exhibits a nonlinear trend with cycle number, corresponding to film coalescence. Field-emission scanning electron microscopy reveals island growth mode of the Pt film at low cycle number with a coalesced film observed after 200 cycles. The metallic coating also exhibits exceptional resistance to mechanical flexing, maintaining up to 93% of unstressed conductivity after bending around cylinders with radii as small as 0.3 cm. Catalytic activity of the as-deposited Pt film is demonstrated via carbon monoxide oxidation to carbon dioxide. This novel low temperature processing allows for the inclusion of highly conductive catalytic material on a number of temperature-sensitive substrates with minimal mass gain for use in such areas as smart textiles and flexible electronics.

  4. Characterization of Copper Coatings Deposited by High-Velocity Oxy-Fuel Spray for Thermal and Electrical Conductivity Applications

    Science.gov (United States)

    Salimijazi, H. R.; Aghaee, M.; Salehi, M.; Garcia, E.

    2017-08-01

    Copper coatings were deposited on steel substrates by high-velocity oxy-fuel spraying. The microstructure of the feedstock copper powders and free-standing coatings were evaluated by optical and scanning electron microscopy. The x-ray diffraction pattern was utilized to determine phase compositions of powders and coatings. Oxygen content was determined by a LECO-T300 oxygen determiner. The thermal conductivity of the coatings was measured in two directions, through-thickness and in-plane by laser flash apparatus. The electrical resistivity of the coatings was measured by the four-point probe method. Oxygen content of the coatings was two times higher than that of the initial powders (0.35-0.37%). The thermal and electrical conductivities of the coatings were different depending on the direction of the measurement. The thermal and electrical conductivity of the coatings improved after annealing for 6 h at a temperature of 600°C.

  5. The correlation of low-velocity impact resistance of graphite-fiber-reinforced composites with matrix properties

    Science.gov (United States)

    Bowles, K. J.

    1986-01-01

    Summarized are basic studies that were conducted to correlate the impact resistance of graphite-fiber-reinforced composites with polymer matrix properties. Three crosslinked epoxy resins and a linear polysulfone were selected as composite matrices. As a group, these resins possess a significantly large range of mechanical properties. The mechanical properties of the resins and their respective composites were measured. Neat resin specimens and unidirectional and crossply composite specimens were impact tested with an instrumented dropweight tester. Impact resistances of the specimens were assessed on the basis of loading capability, energy absorption, and extent of damage.

  6. Highly Conductive Carbon Fiber Reinforced Concrete for Icing Prevention and Curing

    Directory of Open Access Journals (Sweden)

    Oscar Galao

    2016-04-01

    Full Text Available This paper aims to study the feasibility of highly conductive carbon fiber reinforced concrete (CFRC as a self-heating material for ice formation prevention and curing in pavements. Tests were carried out in lab ambient conditions at different fixed voltages and then introduced in a freezer at −15 °C. The specimens inside the freezer were exposed to different fixed voltages when reaching +5 °C for prevention of icing and when reaching the temperature inside the freezer, i.e., −15 °C, for curing of icing. Results show that this concrete could act as a heating element in pavements with risk of ice formation, consuming a reasonable amount of energy for both anti-icing (prevention and deicing (curing, which could turn into an environmentally friendly and cost-effective deicing method.

  7. Wearable Conductive Fiber Sensors for Multi-Axis Human Joint Angle Measurements

    Directory of Open Access Journals (Sweden)

    Asada H Harry

    2005-03-01

    Full Text Available Abstract Background The practice of continuous, long-term monitoring of human joint motion is one that finds many applications, especially in the medical and rehabilitation fields. There is a lack of acceptable devices available to perform such measurements in the field in a reliable and non-intrusive way over a long period of time. The purpose of this study was therefore to develop such a wearable joint monitoring sensor capable of continuous, day-to-day monitoring. Methods A novel technique of incorporating conductive fibers into flexible, skin-tight fabrics surrounding a joint is developed. Resistance changes across these conductive fibers are measured, and directly related to specific single or multi-axis joint angles through the use of a non-linear predictor after an initial, one-time calibration. Because these sensors are intended for multiple uses, an automated registration algorithm has been devised using a sensitivity template matched to an array of sensors spanning the joints of interest. In this way, a sensor array can be taken off and put back on an individual for multiple uses, with the sensors automatically calibrating themselves each time. Results The wearable sensors designed are comfortable, and acceptable for long-term wear in everyday settings. Results have shown the feasibility of this type of sensor, with accurate measurements of joint motion for both a single-axis knee joint and a double axis hip joint when compared to a standard goniometer used to measure joint angles. Self-registration of the sensors was found to be possible with only a few simple motions by the patient. Conclusion After preliminary experiments involving a pants sensing garment for lower body monitoring, it has been seen that this methodology is effective for monitoring joint motion of the hip and knee. This design therefore produces a robust, comfortable, truly wearable joint monitoring device.

  8. Micromechanics model for predicting anisotropic electrical conductivity of carbon fiber composite materials

    Science.gov (United States)

    Haider, Mohammad Faisal; Haider, Md. Mushfique; Yasmeen, Farzana

    2016-07-01

    Heterogeneous materials, such as composites consist of clearly distinguishable constituents (or phases) that show different electrical properties. Multifunctional composites have anisotropic electrical properties that can be tailored for a particular application. The effective anisotropic electrical conductivity of composites is strongly affected by many parameters including volume fractions, distributions, and orientations of constituents. Given the electrical properties of the constituents, one important goal of micromechanics of materials consists of predicting electrical response of the heterogeneous material on the basis of the geometries and properties of the individual phases, a task known as homogenization. The benefit of homogenization is that the behavior of a heterogeneous material can be determined without resorting or testing it. Furthermore, continuum micromechanics can predict the full multi-axial properties and responses of inhomogeneous materials, which are anisotropic in nature. Effective electrical conductivity estimation is performed by using classical micromechanics techniques (composite cylinder assemblage method) that investigates the effect of the fiber/matrix electrical properties and their volume fractions on the micro scale composite response. The composite cylinder assemblage method (CCM) is an analytical theory that is based on the assumption that composites are in a state of periodic structure. The CCM was developed to extend capabilities variable fiber shape/array availability with same volume fraction, interphase analysis, etc. The CCM is a continuum-based micromechanics model that provides closed form expressions for upper level length scales such as macro-scale composite responses in terms of the properties, shapes, orientations and constituent distributions at lower length levels such as the micro-scale.

  9. Pycnogenol efficiency on glycaemia, motor nerve conduction velocity and markers of oxidative stress in mild type diabetes in rats.

    Science.gov (United States)

    Jankyova, S; Kucera, P; Goldenberg, Z; Yaghi, D; Navarova, J; Kyselova, Z; Stolc, S; Klimas, J; Racanska, E; Matyas, S

    2009-08-01

    The aim of this study was to describe the effects of Pycnogenol at various doses on preprandial and postprandial glucose levels, the levels of thiobarbituric acid reactive substances (TBARs) and N-acetyl-beta-d-glucosaminidase (NAGA) and on motor nerve conduction velocity (MNCV) in streptozotocin (STZ)-induced diabetic rats. Pycnogenol treatment (10, 20, 50 mg/kg body weight (b.w.)/day) lasted for 8 weeks after induction of diabetes. Pycnogenol significantly decreased elevated levels of preprandial glycaemia in treated animals at all doses. At doses of 10 mg/kg b.w./day and 20 mg/kg b.w./day it significantly decreased elevated levels of postprandial glycaemia compared with diabetic non-treated animals. Pycnogenol failed to induce a significant decrease of postprandial glycaemia at a dose of 50 mg/kg b.w./day. Pycnogenol improved significantly the impaired MNCV at doses of 10 and 20 mg/kg b.w./day compared with non-treated animals. The levels of TBARs were elevated in diabetic rats. The levels of NAGA increased gradually despite the treatment. Pycnogenol failed to affect the increased levels of TBARs and NAGA. Pycnogenollowered the elevated levels of glycaemia and reduced the decline in motor nerve conduction velocity in STZ-induced diabetic rats. The effect of Pycnogenol on postprandial glycaemic levels and MNCV was not dose-dependent.

  10. Dynamic weakening of fault gouge affected by thermal conductivity of host specimen: implications for the high-velocity weakening mechanisms

    Science.gov (United States)

    Yao, Lu; Ma, Shengli; Shimamoto, Toshihiko; Niemeijer, André

    2015-04-01

    Since many high-velocity weakening mechanisms are thermal in origin, we study the effects of thermal conductivity of host specimen on fault gouge friction behavior at seismic slip rates. By using host specimens made of brass, stainless steel, Ti-Al-V alloy and gabbro with thermal conductivities of 123, 15, 5.8 and 3.25 W/m/K, respectively, the experiments in this study produce completely different temperature conditions within the same gouge under the same slip rates and normal stresses. Fault gouges used in the experiments are a natural illite- and quartz-rich gouge from Longmenshan fault zone and pure periclase (MgO) nanopowder. High-velocity weakening of gouges were more pronounced with decreasing thermal conductivity of the specimens. Particularly, almost no dynamic weakening was observed in the tests performed with brass host specimens, while tests with specimens of gabbro and Ti-Al-V alloy exhibits quite similar dramatic weakening behaviors. Such differences in gouge frictional behavior cannot be explained by original flash heating model, since asperity contacts within the slip zone and experimental conditions are still same, even though host specimens are different. Microstructure observations under scanning and transmission electron microscopes reveal that slip zone materials tend to change from individual ultrafine nanograins to larger sintered grains or aggregates, with decreasing thermal conductivities of host specimens. Calculated temperature together with observed microstructure indicate that bulk temperature rise may be also play an important role in fault weakening, as predicted by a recent theoretical analysis of the role of flash heating within the gouge zone [Proctor et al., 2014]. Current results demonstrate the importance of frictional heating in causing the dynamic weakening of gouge, and the powder lubrication hypothesis is not consistent with our experimental data.

  11. Effect of spaceflight on the maximal shortening velocity, morphology, and enzyme profile of fast- and slow-twitch skeletal muscle fibers in rhesus monkeys

    Science.gov (United States)

    Fitts, R. H.; Romatowski, J. G.; De La Cruz, L.; Widrick, J. J.; Desplanches, D.

    2000-01-01

    Weightlessness has been shown to cause limb muscle wasting and a reduced peak force and power in the antigravity soleus muscle. Despite a reduced peak power, Caiozzo et al. observed an increased maximal shortening velocity in the rat soleus muscle following a 14-day space flight. The major purpose of the present investigation was to determine if weightlessness induced an elevated velocity in the antigravity slow type I fibers of the rhesus monkey (Macaca mulatta), as well as to establish a cellular mechanism for the effect. Spaceflight or models of weightlessness have been shown to increase glucose uptake, elevate muscle glycogen content, and increase fatigability of the soleus muscle. The latter appears to be in part caused by a reduced ability of the slow oxidative fibers to oxidize fats. A second goal of this study was to establish the extent to which weightlessness altered the substrate profile and glycolytic and oxidative enzyme capacity of individual slow- and fast-twitch fibers.

  12. Mechanisms of quinidine-induced depression of maximum upstroke velocity in ovine cardiac Purkinje fibers.

    Science.gov (United States)

    Weld, F M; Coromilas, J; Rottman, J N; Bigger, J T

    1982-03-01

    A major advance in understanding how quinidine depresses maximum upstroke velocity (Vmax) is the Hondeghem-Katzung mathematical model which incorporates voltage-independent rate constants for binding to and unbinding from resting, open, and inactive Na channels, and a voltage shift of -40 mV for the Hodgkin-Huxley h-kinetics of quinidine-associated Na channels. Using a double microelectrode voltage clamp technique to control transmembrane voltage and apply conditioning pulses, we found that quinidine blockade increased as transmembrane voltage became more positive in the range -60 to +40 mV, and that the rate of quinidine dissociation increased as transmembrane voltage became more negative in the range -60 to -140 mV. The relationship of Vmax to transmembrane voltage obtained at drive cycles from 500 msec to 20 seconds conformed to the model modified to include voltage-dependent rate constants without the postulated -40-mV shift for quinidine-associated channels. Thus binding of quinidine to inactive Na channels and unbinding from resting channels are both voltage-dependent and can explain frequency and voltage dependent actions of quinidine on Vmax without any voltage shift for quinidine-associated channels.

  13. A novel intrinsic analgesic mechanism: the enhancement of the conduction failure along polymodal nociceptive C-fibers.

    Science.gov (United States)

    Wang, Xiuchao; Wang, Shan; Wang, Wenting; Duan, Jianhong; Zhang, Ming; Lv, Xiaohua; Niu, Chunxiao; Tan, Chao; Wu, Yuanbin; Yang, Jing; Hu, Sanjue; Xing, Junling

    2016-10-01

    Although conduction failure has been observed in nociceptive C-fibers, little is known regarding its significance or therapeutic potential. In a previous study, we demonstrated that C-fiber conduction failure, which is regarded as an intrinsic self-inhibition mechanism, was reduced in circumstances of painful diabetic neuropathy. In this study, we extend this finding in the complete Freund's adjuvant model of inflammatory pain and validate that the degree of conduction failure decreased and led to a greater amount of pain signals conveyed to the central nervous system. In complete Freund's adjuvant-injected animals, conduction failure occurred in a C-fiber-selective, activity-dependent manner and was associated with an increase in the rising slope of the C-fiber after-hyperpolarization potential. To target conduction failure in a therapeutic modality, we used ZD7288, an antagonist of hyperpolarization-activated, cyclic nucleotide-modulated channels which are activated by hyperpolarization and play a pivotal role in both inflammatory and neuropathic pain. ZD7288 promoted conduction failure by suppressing Ih as a mechanism to reduce the rising slope of the after-hyperpolarization potential. Moreover, perineuronal injection of ZD7288 inhibited abnormal mechanical allodynia and thermal hyperalgesia without affecting motor function or heart rate. Our data highlight the analgesic potential of local ZD7288 application and identify conduction failure as a novel target for analgesic therapeutic development.

  14. Conductivity-based strain monitoring and damage characterization of fiber reinforced cementitious structural components

    Science.gov (United States)

    Hou, Tsung-Chin; Lynch, Jerome P.

    2005-05-01

    In recent years, a new class of cementitious composite has been proposed for the design and construction of durable civil structures. Termed engineered cementitious composites (ECC), ECC utilizes a low volume fraction of short fibers (polymer, steel, carbon) within a cementitious matrix resulting in a composite that strain hardens when loaded in tension. By refining the mechanical properties of the fiber-cement interface, the material exhibits high tolerance to damage. This study explores the electrical properties of ECC materials to monitor their performance and health when employed in the construction of civil structures. In particular, the conductivity of ECC changes in proportion to strain indicating that the material is piezoresistive. In this paper, the piezoresistive properties of various ECC composites are thoroughly explored. To measure the electrical resistance of ECC structures in the field, a low-cost wireless active sensing unit is proposed. The wireless active sensing unit is capable of applying DC and AC voltage signals to ECC elements while simultaneously measuring their corresponding voltages away from the signal input. By locally processing the corresponding input-output electrical signals recorded by the wireless active sensing units, the magnitude of strain in ECC elements can be calculated. In addition to measuring strain, the study seeks to correlate changes in ECC electrical properties to the magnitude of crack damage witnessed in tested specimens. A large number of ECC specimens are tested in the laboratory including a large-scale ECC bridge pier laterally loaded under cyclically repeated drift reversals. The novel self-sensing properties of ECC exploited by a wireless monitoring system hold tremendous promise for the advancement of structural health monitoring of ECC structures.

  15. Excellent thermal conductivity and dielectric properties of polyimide composites filled with silica coated self-passivated aluminum fibers and nanoparticles

    Science.gov (United States)

    Zhou, Yongcun; Bai, Yuanyuan; Yu, Ke; Kang, Yan; Wang, Hong

    2013-06-01

    A polymer based composite was prepared by using modified aluminum fibers and aluminum nanoparticles as fillers in polyimide matrix that resulted in the high thermal conductivity and low relative permittivity. It was found that silica coated aluminum fibers with the multilayer coating structures can significantly reduce the relative permittivity (about 19.6 at 1 MHz) of the composite while keeping lower dielectric loss (0.024 at 1 MHz). The thermal conductivity of composites was significantly increased to 15.2 W/m K. This work shows a useful way to choose proper modifier fillers to improve the composite properties for electronic packaging composite materials.

  16. Analytical solution for peristaltic flow of conducting nanofluids in an asymmetric channel with slip effect of velocity, temperature and concentration

    Directory of Open Access Journals (Sweden)

    S. Sreenadh

    2016-06-01

    Full Text Available The Peristaltic transport of conducting nanofluids under the effect of slip condition in an asymmetric channel is reported in the present work. The mathematical modelling has been carried out under long wavelength and low Reynolds number approximations. The analytical solutions are obtained for pressure rise, nanoparticle concentration, temperature distribution, velocity profiles and stream function. Influence of various parameters on the flow characteristics has been discussed with the help of graphs. The results showed that the pressure rise increases with increasing magnetic effect and decreases with increasing slip parameter. The effects of thermophoresis parameter and Brownian motion parameter on the nanoparticle concentration and temperature distribution are studied. It is observed that the pressure gradient increases with increasing slip parameter and magnetic effect. The trapping phenomenon for different parameters is presented.

  17. Measurement of thermal conductivity of PbTe nanocrystal coated glass fibers by the 3ω method.

    Science.gov (United States)

    Finefrock, Scott W; Wang, Yan; Ferguson, John B; Ward, James V; Fang, Haiyu; Pfluger, Jonathan E; Dudis, Douglas S; Ruan, Xiulin; Wu, Yue

    2013-11-13

    Fiber-based thermoelectric materials can conform to curved surfaces to form energy harvesting devices for waste heat recovery. Here we investigate the thermal conductivity in the axial direction of glass fibers coated with lead telluride (PbTe) nanocrystals using the self-heated 3ω method particularly at low frequency. While prior 3ω measurements on wire-like structures have only been demonstrated for high thermal conductivity materials, the present work demonstrates the suitability of the 3ω method for PbTe nanocrystal coated glass fibers where the low thermal conductivity and high aspect ratio result in a significant thermal radiation effect. We simulate the experiment using a finite-difference method that corrects the thermal radiation effect and extract the thermal conductivity of glass fibers coated by PbTe nanocrystals. The simulation method for radiation correction is shown to be generally much more accurate than analytical methods. We explore the effect of nanocrystal volume fraction on thermal conductivity and obtain results in the range of 0.50-0.93 W/mK near room temperature.

  18. Abnormality of peripheral nerve conduction velocity associated with illness course, symptoms and fasting blood glucose in patients with type 2 diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    Suijing Cui; Jinhua Qiu; Weiliang Luo

    2006-01-01

    BACKGROUND: It has shown that abnormality of peripheral nerve conduction velocity during onset of diabetes mellitus is not related to age and sex, but to symptoms, illness course and level of fasting blood glucose.OBJECTIVE: To measure correlation of abnormality of peripheral nerve conduction velocity with various illness courses, symptoms and levels of fasting blood glucose of patients with type 2 diabetes mellitus.DESIGN: Case analysis.SETTING: Department of Neurology, Central People's Hospital of Huizhou.PARTICIPANTS: A total of 128 patients who were diagnosed as type 2 diabetes mellitus were selected from Central People's Hospital of Huizhou from September 2001 to October 2005. There were 75 males and 53 females aged 32-83 years and the illness course ranged from 1 month to 20 years.METHODS: All 128 patients with type 2 diabetes mellitus received neuro-electrophysiological study and their clinical data were retrospectively analyzed to measure peripheral nerve conduction velocity and fasting blood glucose so as to investigate the correlation of peripheral nerve conduction velocity with clinical symptoms,illness course and levels of fasting blood glucose.MAIN OUTCOME MEASURES: Correlation of peripheral nerve conduction velocity with clinical symptoms, illness course and levels of fasting blood glucose.RESULTS: All 128 patients with type 2 diabetes mellitus were involved in the final analysis. ① Among 128patients, 114 patients had abnormality of peripheral nerve conduction velocity; 110 patients had clinical symptoms, including 102 patients having abnormality of peripheral nerve conduction velocity; 18 patients did not have clinical symptoms, including 12 patients having abnormality of peripheral nerve conduction velocity.There were significant differences between them (x2=8.275, P=0.04). ② Among 128 patients, illness course of 75 patients was equal to or less than 5 years, including 27 patients having abnormality of peripheral nerve conduction velocity

  19. Improving the D2512 Lox Compatibility of Composites by Using Thermally Conductive Graphite Fibers

    Science.gov (United States)

    2005-09-01

    Treatments By A Cold Plasma In Carbon Fiber/ BMI Composites ”, Mat. Res. Soc. Symp. Proc. Vol. 170, Materials Research Society, Pg 321-326, 1990...Fiber/ BMI Composites .”, Mat. Res. Soc. Symp. Proc. V170, Materials Research Society, pg 321-326, 1990 FI38, P.W. Yip and S.S.Lin, “Effect Of

  20. Izmerenie vektora skorosti lazernym dopplerovskim anemometrom (LDA s volokonno-opticheskimi traktami[Measurement of the velocity vector of the laser Doppler anemometer (LDA with fiber-optic tracts

    Directory of Open Access Journals (Sweden)

    S. N. Khotyaintsev

    1982-12-01

    Full Text Available The problems encountered in the development of laser Doppler velocity vector meter optical fiber paths. The scheme of the meter, including three-dimensional velocity meter made by differential circuit. Describes the experimental setup and the results of the experiment by measuring the two projections of the velocity vector.

  1. Using in-situ polymerization of conductive polymers to enhance the electrical properties of solution-processed carbon nanotube films and fibers.

    Science.gov (United States)

    Allen, Ranulfo; Pan, Lijia; Fuller, Gerald G; Bao, Zhenan

    2014-07-09

    Single-walled carbon nanotubes/polymer composites typically have limited conductivity due to a low concentration of nanotubes and the insulating nature of the polymers used. Here we combined a method to align carbon nanotubes with in-situ polymerization of conductive polymer to form composite films and fibers. Use of the conducting polymer raised the conductivity of the films by 2 orders of magnitude. On the other hand, CNT fiber formation was made possible with in-situ polymerization to provide more mechanical support to the CNTs from the formed conducting polymer. The carbon nanotube/conductive polymer composite films and fibers had conductivities of 3300 and 170 S/cm, respectively. The relatively high conductivities were attributed to the polymerization process, which doped both the SWNTs and the polymer. In-situ polymerization can be a promising solution-processable method to enhance the conductivity of carbon nanotube films and fibers.

  2. 'Modal-noise' in single-mode fibers: A cautionary note for high precision radial velocity instruments

    CERN Document Server

    Halverson, Samuel; Mahadevan, Suvrath; Schwab, Christian

    2015-01-01

    Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical 'seeing-limited' instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as 'modal noise', are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, these fibers do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading il...

  3. Conductive, tough, hydrophilic poly(vinyl alcohol)/graphene hybrid fibers for wearable supercapacitors

    Science.gov (United States)

    Chen, Shaohua; Ma, Wujun; Xiang, Hengxue; Cheng, Yanhua; Yang, Shengyuan; Weng, Wei; Zhu, Meifang

    2016-07-01

    Graphene fibers based flexible supercapacitors have great potential as wearable power sources for textile electronics. However, their electrochemical performance is limited by the serious stacking of graphene sheets and their hydrophobicity in aqueous electrolytes. Meanwhile, their brittleness is unfavorable for practical application. Incorporation of nanofillers into graphene fibers has been proved effective for enhancing their capacitance, whereas often leading to deteriorated mechanical strength. Herein we demonstrate that the strength, toughness and capacitive performance of graphene-based fibers can be significantly enhanced simultaneously, simply by incorporating hydrophilic poly(vinyl alcohol) (PVA) into a non-liquid-crystalline graphene oxide (GO) dispersion before wet spinning and chemical reduction. The structure and properties of the resulted PVA/graphene hybrid fibers are systematically investigated, and the mechanism behind these enhancements is discussed in detail. The hybrid fiber with a PVA/GO weight ratio of 10/90 possesses a strength of 186 MPa, a toughness of 11.3 J cm-3, and a capacitance of 241 F cm-3 in 1 M H2SO4. A solid-state yarn supercapacitor assembled from these fibers exhibits a device energy of 5.97 mW h cm-3, and features excellent flexibility and bending stability. This device is robust enough to be integrated into textile and thus promising as wearable power supply for smart textiles.

  4. Effect of body mass index on ulnar nerve conduction velocity, ulnar neuropathy at the elbow, and carpal tunnel syndrome.

    Science.gov (United States)

    Landau, Mark E; Barner, Kristen C; Campbell, William W

    2005-09-01

    Both high and low body mass index (BMI) have been reported as risk factors for ulnar neuropathy at the elbow (UNE), and a high BMI as a risk factor for carpal tunnel syndrome (CTS). To determine whether the extremes of BMI are risk factors for UNE or CTS, and whether BMI affects calculation of median and ulnar motor nerve conduction velocity (NCV), we retrospectively analyzed the electrodiagnostic records of control patients, UNE patients, and CTS patients. The BMI was calculated for 50 patients with a sole diagnosis of UNE and compared to the BMI of 50 patients with CTS and 50 control subjects. The mean BMIs were 25.9 +/- 4.4, 30.1 +/- 5.5, and 28.3 +/- 5.6 for the UNE, CTS, and controls, respectively. By one-way analysis of variance, the difference in BMI between the UNE patients and the normal patients was significant (P ulnar motor NCV across the elbow but not with forearm NCV. Across-elbow (AE) ulnar motor NCV may be falsely increased in patients with a high BMI, probably due to distance measurement factors. Not only do relatively slender individuals have comparatively slower AE ulnar NCVs, they are also at increased risk for developing UNE. Patients with a high BMI are at increased risk for CTS.

  5. Characterization of electrogenerated polypyrrole-benzophenone films coated on poly(pyrrole-methyl metacrylate) optic-conductive fibers.

    Science.gov (United States)

    Abu-Rabeah, Khalil; Atias, Danit; Herrmann, Sebastien; Frenkel, Julia; Tavor, Dorith; Cosnier, Serge; Marks, Robert S

    2009-09-01

    A conductive surface was created for the development of a biosensing platform via chemical polymerization of pyrrole onto the surface of poly(methyl methacrylate) (PMMA) fibers, with a subsequent electrogeneration of a photoactive linker pyrrole-benzophenone (PyBz) monomer on the fiber surface. Irradiation of the benzophenone groups embedded in the polypyrrole (Ppy) films by UV (350 nm) formed active radicals, allowing covalent attachment of the desired biomaterials. Characterization and optimization of this platform were carried out, with the platform showing conductive, stable, thin, controllable, and light-transmissible film features. Various parameters such as time deposition, process temperature, and activator plus pyrrole monomer concentrations were examined in the study. The morphology and permeability of the optic-fiber PMMA fibers were investigated to examine mass transfer ability. Cyclic voltammetry and amperometry techniques were applied to characterize the electrical features of the surface and charge transfer. The platform potential was then demonstrated by the construction of both amperometric and optical biosensors.

  6. Fundamental Studies of Low Velocity Impact Resistance of Graphite Fiber Reinforced Polymer Matrix Composites. Ph.D. Thesis

    Science.gov (United States)

    Bowles, K. J.

    1985-01-01

    A study was conducted to relate the impact resistance of graphite fiber reinforced composites with matrix properties through gaining an understanding of the basic mechanics involved in the deformation and fracture process, and the effect of the polymer matrix structure on these mechanisms. It was found that the resin matrix structure influences the composite impact resistance in at least two ways. The integration of flexibilizers into the polymer chain structure tends to reduce the T sub g and the mechanical properties of the polymer. The reduction in the mechanical properties of the matrix does not enhance the composite impact resistance because it allows matrix controlled failure to initiate impact damage. It was found that when the instrumented dropweight impact tester is used as a means for assessing resin toughness, the resin toughness is enhanced by the ability of the clamped specimen to deflect enough to produce sufficient membrane action to support a significant amount of the load. The results of this study indicate that crossplied composite impact resistance is very much dependent on the matrix mechanical properties.

  7. Safety studies conducted on pecan shell fiber, a food ingredient produced from ground pecan shells

    Directory of Open Access Journals (Sweden)

    Laurie Dolan

    2016-01-01

    Full Text Available Use of pecan shell fiber in human food is presently limited, but could increase pending demonstration of safety. In a 91-day rat study, pecan shell fiber was administered at dietary concentrations of 0 (control, 50 000, 100 000 or 150 000 ppm. There was no effect of the ingredient on body weight of males or females or food consumption of females. Statistically significant increases in food consumption were observed throughout the study in 100 000 and 150 000 ppm males, resulting in intermittent decreases in food efficiency (150 000 ppm males only that were not biologically relevant. All animals survived and no adverse clinical signs or functional changes were attributable to the test material. There were no toxicologically relevant changes in hematology, clinical chemistry or urinalysis parameters or organ weights in rats ingesting pecan shell fiber. Any macroscopic or microscopic findings were incidental, of normal variation and/or of minimal magnitude for test substance association. Pecan shell fiber was non-mutagenic in a bacterial reverse mutation test and non-clastogenic in a mouse peripheral blood micronucleus test. Based on these results, pecan shell fiber has an oral subchronic (13-week no observable adverse effect level (NOAEL of 150 000 ppm in rats and is not genotoxic at the doses analyzed.

  8. Muscle fibre conduction velocity and cardiorespiratory response during incremental cycling exercise in young and older individuals with different training status.

    Science.gov (United States)

    Lenti, M; De Vito, G; Sbriccoli, P; Scotto di Palumbo, A; Sacchetti, M

    2010-08-01

    We investigated the effect of ageing and training on muscle fibre conduction velocity (MFCV) and cardiorespiratory response during incremental cycling exercise. Eight young (YT; 24+/-5 yrs) and eight older (OT; 64+/-3 yrs) cyclists, together with eight young (YU; 27+/-4 yrs) and eight older (OU; 63+/-2 yrs) untrained individuals underwent to an incremental maximal test on a cycle ergometer. Ventilatory threshold (VT), respiratory compensation point (RCP) and maximal oxygen uptake (VO(2)max) were identified and MFCV recorded from the vastus lateralis muscle using surface electromyography with linear arrays electrodes. In YT MFCV increased with the exercise intensity, reaching a peak of 4.99+/-1.02 [m/s] at VT. Thereafter, and up to VO(2)max, MFCV declined. In YU MFCV showed a similar trend although the peak [4.55+/-0.53m/s] was observed, at 75% of VO(2)max an intensity higher than VT (66% of VO(2)max). In both YT and YU MFCV did not decline until RPC, which occurred at 78% VO(2)max in YU and at 92% VO(2)max (P<0.01) in YT. Differently from young individuals, MFCV in older subjects did not increase with exercise intensity. Moreover, maximal MFCV in OU was significantly lower [3.53+/-0.40 m/s;] than that of YT (P<0.005) and YU (P<0.05). The present study shows that, especially in young individuals, MFCV reflects cardiorespiratory response during incremental dynamic cyclic exercise and hence can be used to investigate motor unit recruitment strategies.

  9. Evaluation of the Anisotropic Radiative Conductivity of a Low-Density Carbon Fiber Material from Realistic Microscale Imaging

    Science.gov (United States)

    Nouri, Nima; Panerai, Francesco; Tagavi, Kaveh A.; Mansour, Nagi N.; Martin, Alexandre

    2015-01-01

    The radiative heat transfer inside a low-density carbon fiber insulator is analyzed using a three-dimensional direct simulation model. A robust procedure is presented for the numerical calculation of the geometric configuration factor to compute the radiative energy exchange processes among the small discretized surface areas of the fibrous material. The methodology is applied to a polygonal mesh of a fibrous insulator obtained from three-dimensional microscale imaging of the real material. The anisotropic values of the radiative conductivity are calculated for that geometry. The results yield both directional and thermal dependence of the radiative conductivity.

  10. A Dual Conductance Sensor for Simultaneous Measurement of Void Fraction and Structure Velocity of Downward Two-Phase Flow in a Slightly Inclined Pipe

    Directory of Open Access Journals (Sweden)

    Yeon-Gun Lee

    2017-05-01

    Full Text Available In this study, a new and improved electrical conductance sensor is proposed for application not only to a horizontal pipe, but also an inclined one. The conductance sensor was designed to have a dual layer, each consisting of a three-electrode set to obtain two instantaneous conductance signals in turns, so that the area-averaged void fraction and structure velocity could be measured simultaneously. The optimum configuration of the electrodes was determined through numerical analysis, and the calibration curves for stratified and annular flow were obtained through a series of static experiments. The fabricated conductance sensor was applied to a 45 mm inner diameter U-shaped downward inclined pipe with an inclination angle of 3° under adiabatic air-water flow conditions. In the tests, the superficial velocities ranged from 0.1 to 3.0 m/s for water and from 0.1 to 18 m/s for air. The obtained mean void fraction and the structure velocity from the conductance sensor were validated against the measurement by the wire-mesh sensor and the cross-correlation technique for the visualized images, respectively. The results of the flow regime classification and the corresponding time series of the void fraction at a variety of flow velocities were also discussed.

  11. A Dual Conductance Sensor for Simultaneous Measurement of Void Fraction and Structure Velocity of Downward Two-Phase Flow in a Slightly Inclined Pipe.

    Science.gov (United States)

    Lee, Yeon-Gun; Won, Woo-Youn; Lee, Bo-An; Kim, Sin

    2017-05-08

    In this study, a new and improved electrical conductance sensor is proposed for application not only to a horizontal pipe, but also an inclined one. The conductance sensor was designed to have a dual layer, each consisting of a three-electrode set to obtain two instantaneous conductance signals in turns, so that the area-averaged void fraction and structure velocity could be measured simultaneously. The optimum configuration of the electrodes was determined through numerical analysis, and the calibration curves for stratified and annular flow were obtained through a series of static experiments. The fabricated conductance sensor was applied to a 45 mm inner diameter U-shaped downward inclined pipe with an inclination angle of 3° under adiabatic air-water flow conditions. In the tests, the superficial velocities ranged from 0.1 to 3.0 m/s for water and from 0.1 to 18 m/s for air. The obtained mean void fraction and the structure velocity from the conductance sensor were validated against the measurement by the wire-mesh sensor and the cross-correlation technique for the visualized images, respectively. The results of the flow regime classification and the corresponding time series of the void fraction at a variety of flow velocities were also discussed.

  12. Radial Velocity Fiber-Fed Spectrographs Towards the Discovery of Compact Planets and Pulsations on M Stars

    Science.gov (United States)

    Berdiñas, Zaira M.

    2016-11-01

    radial velocity precision limit attained by an spectrograph. In particular, we focus on correcting the distortions caused by illumination instabilities in fiber-fed spectrographs. I describe our first prototype, the Radiance Characterizer in two dimensions (RadiCa2D), which was specifically designed to correct the Doppler measurements of the CAFE spectrograph. The main underlying idea of RadiCa2D consists in simultaneously monitoring the illumination distortions inside the spectrograph, to correct, in real-time, the effects generated in the final radial velocity measurements. This project is still under development and the final performance of the corrector needs yet to be confirmed.

  13. Low peripheral nerve conduction velocities and amplitudes are strongly related to diabetic microvascular complications in type 1 diabetes: the EURODIAB Prospective Complications Study

    NARCIS (Netherlands)

    Charles, M.; Soedamah-Muthu, S.S.; Tesfaye, S.; Fuller, J.H.; Arezzo, J.C.; Chaturvedi, N.; Witte, D.R.

    2010-01-01

    Objective: Slow nerve conduction velocity and reduction in response amplitude are objective hallmarks of diabetic sensorimotor polyneuropathy. As subjective or clinical indicators of neuropathy do not always match well with the presence of abnormal nerve physiology tests, we evaluated associations t

  14. Technical Project Plan for The Enhanced Thermal Conductivity of Oxide Fuels Through the Addition of High Thermal Conductivity Fibers and Microstructural Engineering

    Energy Technology Data Exchange (ETDEWEB)

    Hollenbach, Daniel F [ORNL; Ott, Larry J [ORNL; Besmann, Theodore M [ORNL; Armstrong, Beth L [ORNL; Wereszczak, Andrew A [ORNL; Lin, Hua-Tay [ORNL; Ellis, Ronald James [ORNL; Becher, Paul F [ORNL; Jubin, Robert Thomas [ORNL; Voit, Stewart L [ORNL

    2010-09-01

    The commercial nuclear power industry is investing heavily in advanced fuels that can produce higher power levels with a higher safety margin and be produced at low cost. Although chemically stable and inexpensive to manufacture, the in-core performance of UO{sub 2} fuel is limited by its low thermal conductivity. There will be enormous financial benefits to any utility that can exploit a new type of fuel that is chemically stable, has a high thermal conductivity, and is inexpensive to manufacture. At reactor operating temperatures, UO{sub 2} has a very low thermal conductivity (<5 W/m {center_dot}K), which decreases with temperature and fuel burnup. This low thermal conductivity limits the rate at which energy can be removed from the fuel, thus limiting the total integrated reactor power. If the fuel thermal conductivity could be increased, nuclear reactors would be able to operate at higher powers and larger safety margins thus decreasing the overall cost of electricity by increasing the power output from existing reactors and decreasing the number of new electrical generating plants needed to meet base load demand. The objective of the work defined herein is to produce an advanced nuclear fuel based on the current UO{sub 2} fuel with superior thermal conductivity and structural integrity that is suitable for current and future nuclear reactors, using the existing fuel fabrication infrastructure with minimal modifications. There are two separate components to the research: (1) Enhanced Thermal Conductivity (ETC) - adding high conductivity fibers to the UO{sub 2} prior to sintering, which act as conduits for moving the heat energy generated within the pellet to the outer surface, (2) Microstructural Engineering (ME) - adding second phase particulates to UO{sub 2} bodies to retard grain growth and to increase thermal conductivity, as well as improve fracture and creep resistance. Different groups will perform the laboratory work for each of these research

  15. Modeling of Thermal Conductivity of CVI-Densified Composites at Fiber and Bundle Level

    Directory of Open Access Journals (Sweden)

    Kang Guan

    2016-12-01

    Full Text Available The evolution of the thermal conductivities of the unidirectional, 2D woven and 3D braided composites during the CVI (chemical vapor infiltration process have been numerically studied by the finite element method. The results show that the dual-scale pores play an important role in the thermal conduction of the CVI-densified composites. According to our results, two thermal conductivity models applicable for CVI process have been developed. The sensitivity analysis demonstrates the parameter with the most influence on the CVI-densified composites’ thermal conductivity is matrix cracking’s density, followed by volume fraction of the bundle and thermal conductance of the matrix cracks, finally by micro-porosity inside the bundles and macro-porosity between the bundles. The obtained results are well consistent with the reported data, thus our models could be useful for designing the processing and performance of the CVI-densified composites.

  16. Median nerve conduction velocity and central conduction time measured with somatosensory evoked potentials in thyroxine-treated infants with Down syndrome

    NARCIS (Netherlands)

    van Trotsenburg, A. S. Paul; Smit, Bert J.; Koelman, Johannes H. T. M.; Sloot, Marijke Dekker-van der; Ridder, Jeannette C. D.; Tijssen, Jan G. P.; de Vijlder, Jan J. M.; Vulsma, Thomas

    2006-01-01

    OBJECTIVE. The aim of this study was to determine whether thyroxine treatment would improve nerve conduction in infants with Down syndrome. METHODS. A single-center, nationwide, randomized, double-blind, clinical trial was performed. Neonates with Down syndrome were assigned randomly to thyroxine (N

  17. Note: Thermal conductivity measurement of individual poly(ether ketone)/carbon nanotube fibers using a steady-state dc thermal bridge method

    Science.gov (United States)

    Moon, Jaeyun; Weaver, Keith; Feng, Bo; Gi Chae, Han; Kumar, Satish; Baek, Jong-Beom; Peterson, G. P.

    2012-01-01

    Customized engineered fibers are currently being used extensively in the aerospace and automobile industries due to the ability to "design in" specific engineering characteristics. Understanding the thermal conductivity of these new fibers is critical for thermal management and design optimization. In the current investigation, a steady-state dc thermal bridge method (DCTBM) is developed to measure the thermal conductivity of individual poly(ether ketone) (PEK)/carbon nanotube (CNT) fibers. For non-conductive fibers, a thin platinum layer was deposited on the test articles to serve as the heater and temperature sensor. The effect of the platinum layer on the thermal conductivity is presented and discussed. DCTBM is first validated using gold and platinum wires (25 μm in diameter) over a temperature ranging from room temperature to 400 K with ±11% uncertainty, and then applied to PEK/CNT fibers with diverse CNT loadings. At a 28 wt. % CNT loading, the thermal conductivity of fibers at 390 K is over 27 Wm-1K-1, which is comparable to some engineering alloys.

  18. Improvement of the electrical conductivity of carbon fibers through the growth of carbon nanofibers.

    Science.gov (United States)

    Moon, Cheol-Whan; Meng, Long-Yue; Im, Seung-Soon; Rhee, Kyong-Yop; Park, Soo-Jin

    2011-07-01

    In this work, carbon nanofibers (CNFs) were synthesized on carbon fiber (CF) surfaces precoated with metal-doped mesoporous silica films. Fe, Ni, and Co were doped in the mesoporous silica films and played the role of catalysts for the decomposition of acetylene to grow CNFs on the CF surfaces. The chemical composition and surface structure of CFs before and after the growth of the CNFs were investigated by EDX, N2 full isotherms, and SEM. The electrical property of the CFs was investigated using a four-probe volume resistivity tester. The SEM results indicated that the CNFs with diameters of 20-100 nm grew uniformly and densely on the CF surfaces. The diameter and length distributions of the CNFs were found to be dependent on the metal that was doped in the mesoporous silica films. The electrical properties of the CFs were enhanced after the CNFs' growth on the CF surfaces, and the CNFs grown over the Ni catalyst with the narrowest diameter distribution gave the lowest volume resistivity to the CFs.

  19. Improved 3-omega measurement of thermal conductivity in liquid, gases, and powders using a metal-coated optical fiber

    Science.gov (United States)

    Schiffres, Scott N.; Malen, Jonathan A.

    2011-06-01

    A novel 3ω thermal conductivity measurement technique called metal-coated 3ω is introduced for use with liquids, gases, powders, and aerogels. This technique employs a micron-scale metal-coated glass fiber as a heater/thermometer that is suspended within the sample. Metal-coated 3ω exceeds alternate 3ω based fluid sensing techniques in a number of key metrics enabling rapid measurements of small samples of materials with very low thermal effusivity (gases), using smaller temperature oscillations with lower parasitic conduction losses. Its advantages relative to existing fluid measurement techniques, including transient hot-wire, steady-state methods, and solid-wire 3ω are discussed. A generalized n-layer concentric cylindrical periodic heating solution that accounts for thermal boundary resistance is presented. Improved sensitivity to boundary conductance is recognized through this model. Metal-coated 3ω was successfully validated through a benchmark study of gases and liquids spanning two-orders of magnitude in thermal conductivity.

  20. Neuro-fuzzy estimation of passive robotic joint safe velocity with embedded sensors of conductive silicone rubber

    Science.gov (United States)

    Al-Shammari, Eiman Tamah; Petković, Dalibor; Danesh, Amir Seyed; Shamshirband, Shahaboddin; Issa, Mirna; Zentner, Lena

    2016-05-01

    Robotic operations need to be safe for unpredictable contacts. Joints with passive compliance with springs can be used for soft robotic contacts. However the joints cannot measure external collision forces. In this investigation was developed one passive compliant joint which have soft contacts with external objects and measurement capabilities. To ensure it, conductive silicone rubber was used as material for modeling of the compliant segments of the robotic joint. These compliant segments represent embedded sensors. The conductive silicone rubber is electrically conductive by deformations. The main task was to obtain elastic absorbers for the external collision forces. These absorbers can be used for measurement in the same time. In other words, the joint has an internal measurement system. Adaptive neuro fuzzy inference system (ANFIS) was used to estimate the safety level of the robotic joint by head injury criteria (HIC).

  1. The Connexin40A96S mutation from a patient with atrial fibrillation causes decreased atrial conduction velocities and sustained episodes of induced atrial fibrillation in mice.

    Science.gov (United States)

    Lübkemeier, Indra; Andrié, René; Lickfett, Lars; Bosen, Felicitas; Stöckigt, Florian; Dobrowolski, Radoslaw; Draffehn, Astrid M; Fregeac, Julien; Schultze, Joachim L; Bukauskas, Feliksas F; Schrickel, Jan Wilko; Willecke, Klaus

    2013-12-01

    Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and a major cause of stroke. In the mammalian heart the gap junction proteins connexin40 (Cx40) and connexin43 (Cx43) are strongly expressed in the atrial myocardium mediating effective propagation of electrical impulses. Different heterozygous mutations in the coding region for Cx40 were identified in patients with AF. We have generated transgenic Cx40A96S mice harboring one of these mutations, the loss-of-function Cx40A96S mutation, as a model for atrial fibrillation. Cx40A96S mice were characterized by immunochemical and electrophysiological analyses. Significantly reduced atrial conduction velocities and strongly prolonged episodes of atrial fibrillation were found after induction in Cx40A96S mice. Analyses of the gating properties of Cx40A96S channels in cultured HeLa cells also revealed significantly lower junctional conductance and enhanced sensitivity voltage gating of Cx40A96S in comparison to Cx40 wild-type gap junctions. This is caused by reduced open probabilities of Cx40A96S gap junction channels, while single channel conductance remained the same. Similar to the corresponding patient, heterozygous Cx40A96S mice revealed normal expression levels and localization of the Cx40 protein. We conclude that heterozygous Cx40A96S mice exhibit prolonged episodes of induced atrial fibrillation and severely reduced atrial conduction velocities similar to the corresponding human patient.

  2. TMEM43 mutation p.S358L alters intercalated disc protein expression and reduces conduction velocity in arrhythmogenic right ventricular cardiomyopathy.

    Directory of Open Access Journals (Sweden)

    Vinayakumar Siragam

    Full Text Available Arrhythmogenic right ventricular cardiomyopathy (ARVC is a myocardial disease characterized by fibro-fatty replacement of myocardium in the right ventricular free wall and frequently results in life-threatening ventricular arrhythmias and sudden cardiac death. A heterozygous missense mutation in the transmembrane protein 43 (TMEM43 gene, p.S358L, has been genetically identified to cause autosomal dominant ARVC type 5 in a founder population from the island of Newfoundland, Canada. Little is known about the function of the TMEM43 protein or how it leads to the pathogenesis of ARVC. We sought to determine the distribution of TMEM43 and the effect of the p.S358L mutation on the expression and distribution of various intercalated (IC disc proteins as well as functional effects on IC disc gap junction dye transfer and conduction velocity in cell culture. Through Western blot analysis, transmission electron microscopy (TEM, immunofluorescence (IF, and electrophysiological analysis, our results showed that the stable expression of p.S358L mutation in the HL-1 cardiac cell line resulted in decreased Zonula Occludens (ZO-1 expression and the loss of ZO-1 localization to cell-cell junctions. Junctional Plakoglobin (JUP and α-catenin proteins were redistributed to the cytoplasm with decreased localization to cell-cell junctions. Connexin-43 (Cx43 phosphorylation was altered, and there was reduced gap junction dye transfer and conduction velocity in mutant TMEM43-transfected cells. These observations suggest that expression of the p.S358L mutant of TMEM43 found in ARVC type 5 may affect localization of proteins involved in conduction, alter gap junction function and reduce conduction velocity in cardiac tissue.

  3. Prostaglandin E1 in conjunction with high doses of vitamin B12 improves nerve conduction velocity of patients with diabetic peripheral neuropathy

    Institute of Scientific and Technical Information of China (English)

    Jilai Li; Zhirong Wan

    2008-01-01

    BACKGROUND: Prostaglandin E1 improves diabetic peripheral neuropathy in symptoms and sensory threshold. Vitamin B1 and methyl-vitamin B12 improve microcirculation to peripheral nerve tissue and promote neurotrophy.OBJECTIVE: To observe motor nerve and sensory nerve conduction velocity in patients with diabetic peripheral neuropathy, prior to and after treatment with prostaglandin E1, vitamin B1 and different doses of vitamin B12.DESIGN, TIME AND SETTING: Randomized, controlled experiment, performed at the Department of Neurology. Beijing Hantian Central Hospital, between February 2002 and September 2007.PARTICIPANTS: A total of 122 patients with type 2 diabetic peripheral neuropathy; 73 males and 49 females were included. All patients met the diagnostic criteria of diabetes mellitus, as determined by the World Health Organization in 1999 and 2006, and also the diagnostic criteria of diabetic peripheral neuropathy. For each subject, conduction disorders in the median nerve and in the common peroneal nerve were observed using electromyogram. Also, after diet and drug treatment, the blood glucose level of subjects was observed to be at a satisfactory level for more than two weeks, and the symptoms of diabetic peripheral neuropathy were not alleviated.METHODS: All patients were randomly divided into the following three groups. A control group (n=40), in which, 100mg vitamin B1 and 500μg vitamin B12 were intramuscularly injected. A vitamin B12 low-dose treated group (n=42), in which 10μg prostaglandin E1 in 250mL physiological saline was intravenously injected once a day and 100mg vitamin B1 and 500μg vitamin B12 was intramuscularly injected once a day. Lastly, a vitamin B12 high-dose treated group (n=40), in which administration was the same as in the vitamin B12 low-dose treated group, except that 500μg vitamin B12 was replaced by 1mg vitamin B12. Administration was performed for four weeks for each group.MAIN OUTCOME MEASURES: The motor nerve and sensory nerve

  4. Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media.

    Science.gov (United States)

    Strutz, Tessa J; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

    2016-08-01

    Successful groundwater remediation by injecting nanoscale zero-valent iron (NZVI) particles requires efficient particle transportation and distribution in the subsurface. This study focused on the influence of injection velocity and particle concentration on the spatial NZVI particle distribution, the deposition processes and on quantifying the induced decrease in hydraulic conductivity (K) as a result of particle retention by lab tests and numerical simulations. Horizontal column tests of 2m length were performed with initial Darcy injection velocities (q0) of 0.5, 1.5, and 4.1m/h and elemental iron input concentrations (Fe(0)in) of 0.6, 10, and 17g/L. Concentrations of Fe(0) in the sand were determined by magnetic susceptibility scans, which provide detailed Fe(0) distribution profiles along the column. NZVI particles were transported farther at higher injection velocity and higher input concentrations. K decreased by one order of magnitude during injection in all experiments, with a stronger decrease after reaching Fe(0) concentrations of about 14-18g/kg(sand). To simulate the observed nanoparticle transport behavior the existing finite-element code OGS has been successfully extended and parameterized for the investigated experiments using blocking, ripening, and straining as governing deposition processes. Considering parameter relationships deduced from single simulations for each experiment (e.g. deposition rate constants as a function of flow velocity) one mean parameter set has been generated reproducing the observations in an adequate way for most cases of the investigated realistic injection conditions. An assessment of the deposition processes related to clogging effects showed that the percentage of retention due to straining and ripening increased during experimental run time resulting in an ongoing reduction of K. Clogging is mainly evoked by straining which dominates particle deposition at higher flow velocities, while blocking and ripening play a

  5. Study on the structure and properties of organic conductive fiber%有机导电纤维的结构和性能研究

    Institute of Scientific and Technical Information of China (English)

    施楣梧; 南燕

    2001-01-01

    This paper studies the properties of carbon coated, carbon composite and metal c ompound composite organic conductive fiber, the properties studied cover many re spect, which include conformation and structure, mechanics, electricity, chemist ry and endurance of conductivity. And both the mechanical property and the abili ty to resist chemical reagent of the conductive fibers involving in this paper c ould meet the requests of the process of textiles. Carbon coated conductive fibe r has the best conductivity, which is suitable to develop anti-static workwear. Carbon composite conductive fiber has medium conductivity, and the conductivity of metal compound composite conductive fiber is the worst among this three type of organic conductive fiber, it's suitable for the development of ordinary text iles.%研究了碳黑涂敷型、碳黑复合型和金属化合物复合型有机导电纤维的形态结构、力学性能、 电学性能、化学性能,以及导电能力的耐久性,这些导电纤维的力学性能、耐化学试剂性能 均可满足纺织品的加工要求。碳黑涂敷型有机导电纤维电阻率最低,适合于防静电工作服面 料;碳黑复合型次之;金属化合物复合型电阻率最高,适合于民用纺织品。

  6. Highly Stretchable Conductive Fibers from Few-Walled Carbon Nanotubes Coated on Poly(m-phenylene isophthalamide) Polymer Core/Shell Structures.

    Science.gov (United States)

    Jiang, Shujuan; Zhang, Hongbo; Song, Shaoqing; Ma, Yanwen; Li, Jinghua; Lee, Gyeong Hee; Han, Qiwei; Liu, Jie

    2015-10-27

    A core/shell stretchable conductive composite of a few-walled carbon nanotube network coated on a poly(m-phenylene isophthalamide) fiber (FWNT/PMIA) was fabricated by a dip-coating method and an annealing process that greatly enhanced interactions between the FWNT network and PMIA core as well as within the FWNT network. The first strain-conductivity test of the as-prepared FWNT/PMIA fiber showed a stretching-induced alignment of nanotubes in the shell during the deformation process and a good conductivity stability with a slight conductivity drop from 109.63 S/cm to 98.74 S/cm (Δσ/σ0 = 10%) at a strain of ∼150% (2.5 times the original length). More importantly, after the first stretching process, the fiber can be recovered with a slight increase in length but a greatly improved conductivity of 167.41 S/cm through an additional annealing treatment. The recovered fiber displays a similarly superb conductivity stability against stretching, with a decrease of only ∼13 S/cm to 154.49 S/cm (Δσ/σ0 = 8%) at a strain of ∼150%. We believe that this conductivity stability came from the formation and maintaining of aligned nanotube structures during the stretching process, which ensures the good tube-tube contacts and the elongation of the FWNT network without losing its conductivity. Such stable conductivity in stretchable fibers will be important for applications in stretchable electronics.

  7. Sound velocity of high-strength polymer with negative thermal expansion coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, R.; Ueno, M.; Okuda, Y.; Burmistrov, S.; Yamanaka, A

    2003-05-01

    Sound velocities of fiber reinforced plastics (FRPs) were measured along the fiber axis at temperatures between 360 and 77 K. We used two kinds of the high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which have negative thermal expansion coefficients. They also have high thermal conductivities and high resistances for flash over voltage, and are expected as new materials for coil bobbins or spacers at cryogenic temperatures. They have very large sound velocities of about 9000 (m/s) at 77 K, which are 4.5 times larger than that of the ordinary polyethylene fiber.

  8. The effect of local corticosteroid injection on F-wave conduction velocity and sympathetic skin response in carpal tunnel syndrome.

    Science.gov (United States)

    Deniz, Orhan; Aygül, Recep; Kotan, Dilcan; Ozdemir, Gökhan; Odabaş, Faruk Omer; Kaya, M Dursun; Ulvi, Hızır

    2012-05-01

    The aim of this study was to evaluate the efficacy of steroid injection for the treatment of the carpal tunnel syndrome (CTS), with F-wave parameters and sympathetic skin response (SSR). Seventeen hands of 10 women patients were treated with local steroid injection with 2-month follow-up. All patients underwent single injection into the carpal tunnel. Response to injection was measured nerve conduction studies (NCSs), median nerve F waves, and SSR before and after treatment. To determine the normal values, 42 hands of 21 healthy women were also studied. There was a significant improvement of sensory and motor nerve conduction values when compared to baseline values (P sensory distal latency and the sensory latency differences between the median and the ulnar nerve were improved 35 and 65%, respectively. The maximum, mean F-wave amplitudes and chronodispersion showed a slight improvement with respect to baseline values and controls, but statistical significance was not achieved after treatment. Although no statistically significant improvements were observed in SSR parameters, slightly decreased amplitudes and increased habituation of SSR were noted at the end of the treatment. The present study shows that the local steroid injection results in improvement in NCSs values, but the F-wave parameters were not effectual in short-term outcome of CTS treatment. These findings suggest that the sensory latency differences between the median and the ulnar wrist-to-digit 4 are better parameters in the median nerve recovery after treatment than the median sensory distal latency. Furthermore, the SSR does not seem to be a sensitive method in follow-up of CTS treatment.

  9. Effect of high-frequency repetitive transcranial magnetic stimulation on motor cortical excitability and sensory nerve conduction velocity in subacute-stage incomplete spinal cord injury patients.

    Science.gov (United States)

    Cha, Hyun Gyu; Ji, Sang-Goo; Kim, Myoung-Kwon

    2016-07-01

    [Purpose] The aim of the present study was to determine whether repetitive transcranial magnetic stimulation can improve sensory recovery of the lower extremities in subacute-stage spinal cord injury patients. [Subjects and Methods] This study was conducted on 20 subjects with diagnosed paraplegia due to spinal cord injury. These 20 subjects were allocated to an experimental group of 10 subjects that underwent active repetitive transcranial magnetic stimulation or to a control group of 10 subjects that underwent sham repetitive transcranial magnetic stimulation. The SCI patients in the experimental group underwent active repetitive transcranial magnetic stimulation and conventional rehabilitation therapy, whereas the spinal cord injury patients in the control group underwent sham repetitive transcranial magnetic stimulation and conventional rehabilitation therapy. Participants in both groups received therapy five days per week for six-weeks. Latency, amplitude, and sensory nerve conduction velocity were assessed before and after the six week therapy period. [Results] A significant intergroup difference was observed for posttreatment velocity gains, but no significant intergroup difference was observed for amplitude or latency. [Conclusion] repetitive transcranial magnetic stimulation may be improve sensory recovery of the lower extremities in subacute-stage spinal cord injury patients.

  10. The tissue velocity imaging and strain rate imaging in the assessment of interatrial electromechanical conduction in patients with sick sinus syndrome before and after pacemaker implantation.

    Science.gov (United States)

    Zheng, Xiaozhi; Ji, Ping; Mao, Hongwei; Hu, Jianqun

    2011-05-01

    Tissue velocity imaging (TVI) and strain rate imaging (SRI) were recently introduced to quantify myocardial mechanical activity in patients receiving cardiac resynchronization therapy. To clear whether atrial-demand-based (AAI) (R) atrial pacing can fully simulate the electromechanical conduction of physiological state and to clarify which one is more appropriate for the assessment of electromechanical activity of the heart between TVI and SRI, 30 normal subjects and 31 patients with sick sinus syndrome (SSS) before and after AAI(R) pacemaker implantation (PI) were investigated in this study. The results showed that the time intervals (ms), P-SRa assessed by SRI (not P-Va assessed by TVI) prolonged step by step from the lateral wall of the right atrium (RA), the interatrial septum (IAS) and the left atrium (LA) in normal subjects(5.01±0.62, 17.05±3.54 and 45.09±12.26, pIAS and LA in patients with SSS before PI (p>0.05), and they were significant longer than those of normal subjects (pIAS to LA. At the same time, the peak velocities and the peak strain rates during atrial contraction also returned to normal values from lower levels. These data suggested that AAI(R) atrial pacing can successfully reverse the abnormal interatrial electromechanical conduction in patients with SSS, and SRI is more appropriate for the assessment of the electromechanical activity of atrial wall than TVI.

  11. Conductivity and touch-sensor application for atomic layer deposition ZnO and Al:ZnO on nylon nonwoven fiber mats

    Energy Technology Data Exchange (ETDEWEB)

    Sweet, William J.; Oldham, Christopher J.; Parsons, Gregory N., E-mail: parsons@ncsu.edu [Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2015-01-15

    Flexible electronics and wearable technology represent a novel and growing market for next generation devices. In this work, the authors deposit conductive zinc oxide films by atomic layer deposition onto nylon-6 nonwoven fiber mats and spun-cast films, and quantify the impact that deposition temperature, coating thickness, and aluminum doping have on the conductivity of the coated substrates. The authors produce aluminum doped zinc oxide (AZO) coated fibers with conductivity of 230 S/cm, which is ∼6× more conductive than ZnO coated fibers. Furthermore, the authors demonstrate AZO coated fibers maintain 62% of their conductivity after being bent around a 3 mm radius cylinder. As an example application, the authors fabricate an “all-fiber” pressure sensor using AZO coated nylon-6 electrodes. The sensor signal scales exponentially under small applied force (<50 g/cm{sup 2}), yielding a ∼10{sup 6}× current change under 200 g/cm{sup 2}. This lightweight, flexible, and breathable touch/force sensor could function, for example, as an electronically active nonwoven for personal or engineered system analysis and diagnostics.

  12. 应用MEP、NCV联合诊断糖尿病性神经病%Diagnosis of diabetic neuropathy by motor evoked potentials and nerve conduction velocity

    Institute of Scientific and Technical Information of China (English)

    范秀玉; 邵会全; 董玉芳; 王晶; 魏淑芹

    2001-01-01

    Objective:To study the diagnostic value of Motor evokedpotentials(MEP) and nerve conduction velocity(NCV) in the lesions of motor nerve center,nerve root and peripheral nerve in patients with diabetes mellitus(DM).Methods: MEPs by electrostimulation of cerebral cortex and spinal cord and NCV were performed in 50 patients with DM.Results:The abnormality rate of MEPS was 82%(41/50).The main changes were the prolonged latency and unclear wave form.Central motor conduction time(CMCT) was prolonged in some patients.There was positive correlation between the course of disease and the abnormality rate of MEP.There was no significant relation between the result of MEP and the level of fasting blood sugar.The abnormality rate of NCV was 70%,the main changes were decreased motor conduction velocity(MCV) and sensory conduction velocity(SCV).Conclusions:MEP and NCVmight have an important role in the diagnosis of pyramid tract lesions,nerve root and peripheral nerve lesions,combination of the two methods may provide more complete and objective indexes for function of nevous system in patients with DM.%目的:探讨运动诱发电位(MEP)、神经传导速度(NCV)检测对糖尿病(DM)运动神经中枢及神经根、周围神经病变的诊断价值。方法:检测50例DM病人的MEP及NCV。结果:MEP异常率82%(41/50)。表现皮层、脊髓刺激MEP潜伏期延迟、波形分化欠佳,部分伴有中枢运动传导时间(CMCT)异常。MEP异常率与病程长短呈正相关;空腹血糖水平对MEP结果无明显影响。NCV异常率70%,主要表现运动神经传导速度(MCV)、感觉神经传导速度(SCV)减慢。结论:MEP、NCV检查对诊断DM的锥体束功能损害及神经根、周围神经病变有重要价值,二者结合可对DM的神经系统功能提供全面客观指标。

  13. Quantitative assessment on the orientation and distribution of carbon fibers in a conductive polymer composite using high-frequency ultrasound.

    Science.gov (United States)

    Lin, Yi-Hsun; Huang, Chih-Chung; Wang, Shyh-Hau

    2012-05-01

    Conductive polymer composites, typically fabricated from a mix of conductive fillers and a polymer substrate, are commonly applied as bipolar plates in a fuel cell stack. Electrical conductivity is a crucial property that greatly depends on the distribution and orientation of the fillers. In this study, a 50-MHz ultrasound imaging system and analysis techniques capable of nondestructively assessing the properties of carbon fibers (CFs) in conductive polymer composites were developed. Composite materials containing a mix of polycarbonate substrates and 0 to 0.3 wt% of CFs were prepared using an injection molding technique. Ultrasonic A-line signals and C-scan images were acquired from each composite sample in regions at a depth of 0.15 mm beneath the sample surface (region A) and those at a depth of 0.3 mm (region B). The integrated backscatter (IB) and the Nakagami statistical parameter were calculated to quantitatively assess the samples. The area ratio, defined as the percentage of areas composed of CF images normalized by that of the whole C-scan image, was applied to further quantify the orientation of CFs perpendicular to the sample surface. Corresponding to the increase in CF concentrations from 0.1 to 0.3 wt%, the average IB and Nakagami parameter (m) of the composite samples increased from -78.10 ± 2.20 (mean ± standard deviation) to -72.66 ± 1.40 dB and from 0.024 ± 0.012 to 0.048 ± 0.011, respectively. The corresponding area ratios were respectively estimated to be 0.78 ± 0.35%, 2.33 ± 0.66%, and 2.20 ± 0.60% in region A of the samples; those of CFs with a perpendicular orientation were 0.04 ± 0.03%, 0.08 ± 0.02%, and 0.12 ± 0.05%. The area ratios in region B of the samples were calculated to be 1.19 ± 0.54%, 2.81 ± 0.42%, and 2.64 ± 0.76%, and those of CFs with a perpendicular orientation were 0.07 ± 0.04%, 0.12 ± 0.04%, and 0.14 ± 0.03%. According to the results of the orientations and ultrasonic images, CFs tended to distribute more

  14. Wet-spinning of PEDOT:PSS/Functionalized-SWNTs Composite: a Facile Route Toward Production of Strong and Highly Conducting Multifunctional Fibers

    Science.gov (United States)

    Jalili, Rouhollah; Razal, Joselito M.; Wallace, Gordon G.

    2013-01-01

    With the aim of fabricating multifunctional fibers with enhanced mechanical properties, electrical conductivity and electrochemical performance, we develop wet-spinning of composite formulation based on functionalized PEG-SWNT and PEDOT:PSS. The method of addition and loading are directly correlated to the quality and the ease of spinnability of the formulation and to the mechanical and electrical properties of the resultant fibers. Both the fiber modulus (Y) and strength (σ) scaled linearly with PEG-SWNT volume fraction (Vf). A remarkable reinforcement rate of dY/dVf = 417 GPa and dσ/dVf = 4 GPa were obtained when PEG-SWNTs at Vf ≤ 0.02. Further increase of PEG-SWNTs loading (i.e. up to Vf 0.12) resulted in further enhancements up to 22.8 GPa and 254 MPa in Modulus and ultimate stress, respectively. We also show the enhancement of electrochemical supercapacitor performance of composite fibers. These outstanding mechanical, electrical and electrochemical performances place these fibers among the best performing multifunctional composite fibers. PMID:24336593

  15. Effects of new antiarrhythmic agent SS-68 on excitation conduction, electrical activity in Purkinje fibers and pulmonary veins: Assessment of safety and side effects risk.

    Science.gov (United States)

    Bogus, Saida K; Kuzmin, Vladislav S; Abramochkin, Denis V; Suzdalev, Konstantin F; Galenko-Yaroshevsky, Pavel A

    2017-03-02

    The compound SS-68 has been selected among numerous new derivatives of indole and demonstrated antiarrhythmic effects in animal models. The present study concerns several aspects of SS-68 safety and efficacy as a potential antiarrhythmic drug. The first estimation of atrioventricular conduction in mammalian heart under SS-68 has been carried out; effects of SS-68 in Purkinje fibers and myocardium of pulmonary veins have been investigated. The drug weakly affects cardiac atrioventricular conduction: only high concentrations of SS-68 (≥10 μmol/L) significantly decrease this parameter. Also, the drug weakly affects Purkinje fibers automaticity, but effectively alters action potential waveform in Purkinje fibers in a concentration-dependent manner. SS-68 (0.1-100 μmol/L) failed to induce any early or delayed afterdepolarizations in Purkinje fibers both in basal conditions and under provocation of proarrhythmic activity by norepinephrine (NE). Moreover, 10 μmol/L SS-68 suppressed NE-induced extra-beats and rapid firing in Purkinje fibers. In pulmonary veins only high concentrations of SS-68 significantly increased action potential duration, while lower concentrations (0.1-1 μmol/L) were ineffective. Also, 0.1-100 μmol/L SS-68 was unable to elicit arrhythmogenic alternations of action potential waveform in pulmonary veins. In conclusion, SS-68 has no proarrhythmic effects, such as afterdepolarizations or abnormal automaticity in used experimental models.

  16. Enlightening the ultrahigh electrical conductivities of doped double-wall carbon nanotube fibers by Raman spectroscopy and first-principles calculations.

    Science.gov (United States)

    Tristant, Damien; Zubair, Ahmed; Puech, Pascal; Neumayer, Frédéric; Moyano, Sébastien; Headrick, Robert J; Tsentalovich, Dmitri E; Young, Colin C; Gerber, Iann C; Pasquali, Matteo; Kono, Junichiro; Leotin, Jean

    2016-12-01

    Highly aligned, packed, and doped carbon nanotube (CNT) fibers with electrical conductivities approaching that of copper have recently become available. These fibers are promising for high-power electrical applications that require light-weight, high current-carrying capacity cables. However, a microscopic understanding of how doping affects the electrical conductance of such CNT fibers in a quantitative manner has been lacking. Here, we performed Raman spectroscopy measurements combined with first-principles calculations to determine the position of the average Fermi energy and to obtain the temperature of chlorosulfonic-acid-doped double-wall CNT fibers under high current. Due to the unique way in which double-wall CNT Raman spectra depend on doping, it is possible to use Raman data to determine the doping level quantitatively. The correspondence between the Fermi level shift and the carbon charge transfer is derived from a tight-binding model and validated by several calculations. For the doped fiber, we were able to associate an average Fermi energy shift of ∼-0.7 eV with a conductance increase by a factor of ∼5. Furthermore, since current induces heating, local temperature determination is possible. Through the Stokes-to-anti-Stokes intensity ratio of the G-band peaks, we estimated a temperature rise at the fiber surface of ∼135 K at a current density of 2.27 × 10(8) A m(-2) identical to that from the G-band shift, suggesting that thermalization between CNTs is well achieved.

  17. The relation between gas density and velocity power spectra in galaxy clusters: high-resolution hydrodynamic simulations and the role of conduction

    CERN Document Server

    Gaspari, M; Nagai, D; Lau, E T; Zhuravleva, I

    2014-01-01

    Exploring the ICM power spectrum can help us to probe the physics of galaxy clusters. Using high-resolution 3D plasma simulations, we study the statistics of the velocity field and its relation with the thermodynamic perturbations. The normalization of the ICM spectrum (density, entropy, or pressure) is linearly tied to the level of large-scale motions, which excite both gravity and sound waves due to stratification. For low 3D Mach number M~0.25, gravity waves mainly drive entropy perturbations, traced by preferentially tangential turbulence. For M>0.5, sound waves start to significantly contribute, passing the leading role to compressive pressure fluctuations, associated with isotropic turbulence (or a slight radial bias). Density and temperature fluctuations are then characterized by the dominant process: isobaric (low M), adiabatic (high M), or isothermal (strong conduction). Most clusters reside in the intermediate regime, showing a mixture of gravity and sound waves, hence drifting towards isotropic vel...

  18. Study on the application of organic conductive fiber%有机导电纤维的应用方法研究

    Institute of Scientific and Technical Information of China (English)

    施楣梧; 刘俊卿; 南燕

    2001-01-01

    This paper studies the method of compounding organic conductive fiber with ordinary fiber during the process of spinning and weaving, and the study of the relationship between charge density of the fabric and the amount of the organic conductive fiber added was also made. The type of the organic conductive fiber studied covers carbon coated, carbon composite and metal compounds composite.%在探讨有机导电纤维的选用原则及其在化纤纺丝、纺纱和织造过程中与常规纤维的复合方法的基础上,研究了碳黑涂敷型、碳黑复合型和金属化合物复合型有机导电纤维的添加量与和织物电荷面密度的关系,以及碳黑复合型有机导电纤维用于毛涤织物时的抗静电效果。

  19. Can carbon nanotube fibers achieve the ultimate conductivity?—Coupled-mode analysis for electron transport through the carbon nanotube contact

    Science.gov (United States)

    Xu, Fangbo; Sadrzadeh, Arta; Xu, Zhiping; Yakobson, Boris I.

    2013-08-01

    Recent measurements of carbon nanotube (CNT) fibers electrical conductivity still show the values lower than that of individual CNTs, by about one magnitude order. The imperfections of manufacturing process and constituent components are described as culprits. What if every segment is made perfect? In this work, we study the quantum conductance through the parallel junction of flawless armchair CNTs using tight-binding method in conjunction with non-equilibrium Green's function approach. Short-range oscillations within the long-range oscillations as well as decaying envelopes are all observed in the computed Fermi-level (low bias) conductance as a function of contact length, L. The propagation of CNTs' Bloch waves is cast in the coupled-mode formalism and helps to reveal the quantum interference nature of various behaviors of conductance. Our analysis shows that the Bloch waves at the Fermi-level propagate through a parallel junction without reflection only at an optimal value of contact length. For quite a long junction, however, the conductance at the Fermi level diminishes due to the perturbation of periodic potential field of close-packed CNTs. Thus, a macroscopic fiber, containing an infinite number of junctions, forms a filter that permits passage of electrons with specific wave vectors, and these wave vectors are determined by the collection of all the junction lengths. We also argue that the energy gap introduced by long junctions can be overcome by small voltage (˜0.04 V) across the whole fiber. Overall, developing long individual all-armchair metallic CNTs serves as a promising way to the manufacture of high-conductivity fibers.

  20. Low velocity impact response of carbon fiber laminates fabricated by pulsed infusion: A review of damage investigation and semi-empirical models validation

    Science.gov (United States)

    Antonucci, V.; Caputo, F.; Ferraro, P.; Langella, A.; Lopresto, V.; Pagliarulo, V.; Ricciardi, M. R.; Riccio, A.; Toscano, C.

    2016-02-01

    The research reported in this paper was aimed mainly to investigate the different NDE techniques on specimens made by a new process labeled as "pulsed infusion", very crucial for voids content under critical loading conditions. The impact load, in fact, is critical for composite laminates due to their anisotropy, in particular in extreme temperature conditions due to their brittleness. An additional and very relevant aim was to collect a large number of experimental results to supply useful information for the numerical models needed to simulate the dynamic behavior of composite laminates. At the aim to investigate the response under dynamic loads of laminates fabricated by a new vacuum assisted technology labeled as "pulsed infusion", rectangular carbon fiber composite specimens were subjected to low velocity impact tests. Experimental tests up to complete penetration and at different energy levels, were carried out by a modular falling weight tower. All the parameters related to the phenomenon, like penetration energy, maximum force and indentation depths, were used to validate existing semi-empirical and numerical models. The largely used ultra sound technique (US) was adopted to investigate the delamination together with the thermo graphic technique. The results of the measurements were compared with data obtained on the same specimens by holographic analysis (ESPI). One of the scope was to investigate the crucial internal impact damage and assess the ability of an unconventional ND system (ESPI) in giving right information about non-visual damage generated inside composite laminates subjected to dynamic loads. Moreover, some of the specimens were cut to allow the fractographic analysis. The efficiency of the above mentioned new fabrication technology was studied also comparing the results with measurements from literature on impacted autoclave cured laminates. By the comparison between the results, good agreements were found denoting the efficiency and the

  1. Study on the electric conduction function of carbon black and carbon fiber diphasic electrically conductive concrete%炭黑碳纤维复相导电混凝土的导电性能研究

    Institute of Scientific and Technical Information of China (English)

    卢珍; 吴献; 杨昆

    2014-01-01

    It aimed at the research on the electric conduction function carbon black and carbon fiber diphasic electrically conductive concrete,and analyse the change of resistivity.The methodology adopted as theoretical basis and experimental basis can be used in deicing or snow-melting in future.Carbon black and carbon fiber as the electric conduction is used to improve the electric conduction function of concrete.Conduct the experiment of the electric conduction function of carbon black and carbon fiber diphasic electrically conductive con-crete.The effect of temperature,humidity and plus voltage on resistivity of carbon black and carbon fiber diphasic electricall conductive concrete was analysed.When environment chang,the electric conduction function of concrete will chang too.As the rise of temperature the experimental results showed that the resistivity of carbon black and carbon fiber diphasic electrically conductive concrete will reduct in a certain degree.The resistivity in dry state was higher than the state of wet. As the rise of plus voltage the resistivity of carbon black and car-bon fiber diphasic electrically conductive concrete will reduct in a certain degree.When the voltage is to a certain number ,the resistivity trend to be stabile.%研究了炭黑碳纤维复相导电混凝土的导电性能,分析了导电混凝土的电阻率变化,为实际应用于道路融雪化冰提供理论依据与试验依据。利用纳米导电炭黑和碳纤维作为导电相来改善混凝土的导电性能,进行炭黑碳纤维复相导电混凝土的导电性能试验,分析环境温度、干湿度和外加电压对炭黑碳纤维导电混凝土电阻率的影响。导电混凝土的电阻率受温度、湿度和外加电压的影响,当环境条件发生变化时,导电混凝土的导电性能也会发生变化。炭黑碳纤维复相导电混凝土的电阻率随着温度的升高出现一定程度的减小;干燥状态下的电阻率高于潮湿

  2. Relation of Na+, K(+)-ATPase to delayed motor nerve conduction velocity: effect of aldose reductase inhibitor, ADN-138, on Na+, K(+)-ATPase activity.

    Science.gov (United States)

    Hirata, Y; Okada, K

    1990-06-01

    The role of sorbitol, myo-inositol, and Na+, K(+)-adenosine triphosphatase (ATPase) activity on motor nerve conduction velocity (MNCV) in streptozotocin (STZ)-diabetic rats was studied. Reduction of MNCV and Na+, K(+)-ATPase in caudal nerves appeared after 3 weeks of diabetes, and at this time treatment with aldose reductase inhibitor (ARI), ADN-138 and 1% myo-inositol supplement was begun. One percent myo-inositol supplement for 3 weeks resulted in a significant increase in myo-inositol levels in diabetic nerves, but left MNCV and sorbitol levels unchanged. In contrast, treatment with ADN-138 for 3 weeks reduced sorbitol levels in diabetic nerves and resulted in significant increases in MNCV and Na+, K(+)-ATPase in the nerves. Since ADN-138 did not restore myo-inositol levels, the increase in Na+, K(+)-ATPase levels by ADN-138 treatment was independent of myo-inositol levels. Also, nerve Na+ levels in ADN-138-treated rats were reduced and the ratio of K+ to Na+ was raised, while 1% myo-inositol supplement did not affect them. These results suggest that treatment with ADN-138 elevates MNCV through a series of processes: ARI----reduction of sorbitol level----increase in Na+, K(+)-ATPase activity----correction of K+, Na+ imbalance----increase in MNCV.

  3. Electromyography and nerve conduction velocity for the evaluation of the infraspinatus muscle and the suprascapular nerve in professional beach volleyball players.

    Science.gov (United States)

    Lajtai, Georg; Wieser, Karl; Ofner, Michael; Raimann, Gustav; Aitzetmüller, Gernot; Jost, Bernhard

    2012-10-01

    Beach volleyball is an overhead sport with a high prevalence of infraspinatus muscle atrophy of the hitting shoulder. Infraspinatus muscle atrophy seems to be caused by a repetitive traction injury of the suprascapular nerve. Early pathological findings might be assessed with surface electromyography (EMG) and nerve conduction velocity (NCV) measurements. Cross-sectional study; Level of evidence, 3. Fully competitive professional beach volleyball players were assessed with a structured interview, shoulder examination, strength measurements (external rotation and elevation), and neurophysiological examination (surface EMG and NCV of the infraspinatus and supraspinatus muscles and the suprascapular nerve, respectively) during the Beach Volleyball Grand Slam tournament 2010 in Klagenfurt, Austria. Thirty-five men with an average age of 28 years were examined. Visible infraspinatus atrophy was found in 12 players (34%), of which 8 (23%) had slight atrophy and 4 (11%) had severe atrophy. External rotation (90%; P volleyball players have a high frequency of infraspinatus atrophy (34%) and significantly reduced shoulder strength of the hitting shoulder. These findings are not associated with demographic factors. Electromyography and NCV measurements suggest a suprascapular nerve involvement caused by repetitive strain injuries of the nerve. External rotation strength measurements and NCV measurements can detect a side-to-side difference early, while EMG may show compensation mechanisms for progressive damaging of the suprascapular nerve and, as a result, loss of infraspinatus muscle strength.

  4. Transverse Uniaxial Composite Thermal Properties Data Base of Thermally Conductive Graphite Fibers with and without Contiguous Grown Graphite Fins

    Science.gov (United States)

    2013-07-01

    43 FG4, Opened Reactor Chamber Door...unlimited.      Figure FG3, Optical Pyrometer Location And Read Out Figure FG4, Opened Reactor Chamber Door Figure FG5, Heater Stage, Inserted...in each hole. A perpendicular hole was drilled halfway through the rod into the each fiber bundle hole and threaded for nylon set screws . The

  5. Enhancement of Li Ion Conductivity by Electrospun Polymer Fibers and Direct Fabrication of Solvent-Free Separator Membranes for Li Ion Batteries.

    Science.gov (United States)

    Freitag, Katharina M; Kirchhain, Holger; Wüllen, Leo van; Nilges, Tom

    2017-02-20

    Poly(ethylene oxide) (PEO)-based polymer fibers, containing different amounts of the conductive salt LiBF4 and the plasticizer succinonitrile, were prepared by an electrospinning process. This process resulted in fiber membranes of several square centimeters area and an overall thickness of ∼100 μm. All membranes are characterized by scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, impedance spectroscopy, cyclic voltammetry (CV), and solid-state NMR spectroscopy, to evaluate the influence of the preparation process and the composition on the conductivity of the materials. Impedance spectroscopy was used to measure the conductivities and activation barriers for the different membranes. The highest conductivity of 2 × 10(-4) S/cm at room temperature and 9 × 10(-4) S/cm at 328 K is reached for a PEO/SN/LiBF4 (36:8:1) membrane, featuring an activation energy of 31 kJ/mol. Li mobilities, as deduced from the evaluation of the temperature dependence of the (7)Li NMR line width and the overall electrochemical performance, are found to be distinctively superior to nonspun samples, synthesized via conventional solution casting. The same trend was found for the conductivities. NMR spectroscopy clearly substantiated that the mobility of the PEO segments drastically increases with the addition of succinonitrile pushing the conductivity to reasonable high values. In CV experiments the reversible Li transport through the dry membrane was evaluated and proved. This study shows that electrospinning provides a direct synthesis of solvent-free solid-state electrolyte membranes, ready to use in electrochemical applications.

  6. Repetition rate stabilization of an erbium-doped all-fiber laser via opto-mechanical control of the intracavity group velocity

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Xuling; He, Boqu; Zhao, Jian; Liu, Yang; Bai, Dongbi; Wang, Chao; Liu, Geping; Luo, Daping; Liu, Fengjiang; Li, Wenxue; Zeng, Heping, E-mail: hpzeng@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Yang, Kangwen; Hao, Qiang [Shanghai Key Laboratory of Modern Optical System, Engineering Research Center of Optical Instrument and System (Ministry of Education), School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2015-01-19

    We present a method for stabilizing the repetition rate of an erbium-doped all-fiber laser by inserting an electronic polarization controller (EPC) in the fiber laser cavity. The device exhibited good integration, low cost, and convenient operation. Such a repetition rate stabilization may facilitate an all-fiber laser comb system with high integration. The repetition rate was phase-locked to a Rb reference more than 72 h with a low feedback voltage applied to one channel of the EPC. The repetition rate was 74.6 MHz. The standard deviation and the repetition rate linewidth were 1.4 and 1.7 mHz, respectively.

  7. Conductive nano composites based on cellulose nano fiber coated poly aniline via in situ polymerization; Nanocompositos condutores de nanofibras de celulose recobertas com polianilina via polimerizacao in situ

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Michael J. da; Sanches, Alex O.; Malmonge, Luiz F.; Malmonge, Jose A. [Grupo de Polimero, Depto de Fisica e Quimica, Faculdade de Engenharia de Ilha Solteira, Universidade Estadual Paulista, Ilha Solteira, SP (Brazil); Medeiros, Eliton S. de [Depto de Engenharia de Materiais, Universidade Federal da Paraiba, Joao Pessoa, PB (Brazil); Rosa, Morsyleide F. [Embrapa Agroindustria Tropical, Fortaleza, CE (Brazil)

    2011-07-01

    Cellulose nano fiber (CNF) was extracted by acid hydrolysis from cotton microfibril and nano composites of CNF/PANI-DBSA were obtained by in situ polymerization of aniline onto CNF. The ratios between DBSA/aniline and aniline/oxidant were varied and the nano composites were characterized by four probes direct current (dc) electrical conductivity, ultraviolet-visible (UV-Vis-NIR) and FTIR spectroscopy and X-ray diffraction (XRD). Electrical conductive about {approx}10{sup -1}S/cm was research and was independent of DBSA/aniline molar ratio between 2-4 and the aniline/oxidant molar ratio between 1-5. X-ray patterns of the samples show crystalline peaks characteristic of cellulose I. The FTIR spectra confirmed the presence of PANI and CNF in all samples. (author)

  8. Oil sorption by lignocellulosic fibers

    Science.gov (United States)

    Beom-Goo. Lee; James S. Han; Roger M. Rowell

    1999-01-01

    The oil sorption capacities of cotton fiber, kenaf bast fiber, kenaf core fiber, and moss fiber were compared after refining, extraction, and reduction in particle sizes. The tests were conducted on diesel oil in a pure form. Cotton fiber showed the highest capacity, followed by kenaf core and bast fibers. Wetting, extraction, and reduction in particle size all...

  9. Thermal Conductivity of Diamond Packed Electrospun PAN-Based Carbon Fibers Incorporated with Multi Wall Carbon Nanotubes.

    Science.gov (United States)

    Dong, Qi; Lu, Chunyuan; Tulugan, Kelimu; Jin, Chunzi; Yoon, Soo Jong; Park, Yeong Min; Kim, Tae Gyu

    2016-02-01

    Multi wall carbon nanotubes (MWCNTs) and diamond are renowned as superlative material due to their relatively high thermal conductivity and hardness while comparing with any bulk materials. In this research, polyacrylonitrile (PAN) solution incorporated with MWCNTs at an alteration of mass fractions (0 wt%, 0.6 wt%, 1 wt%, 2 wt%) were fabricated via electrospinning under optimized parameters. Dried composite nanofibers were stabilized and carbonized, after which water base polytrafluorethylene (PTFE) mixed with nano diamond powder solution was spin coated on them. Scanning electron microscopy, Raman spectroscopy, X-ray scattering and Laserflash thermal conductivity were used to characterize the composite nanofiber sheets. The result shows that the thermal conductivity increased to 4.825 W/m K from 2.061 W/mK. The improvement of thermal conductivities is suggesting the incorporation of MWCNTs.

  10. Energy velocity and group velocity

    Institute of Scientific and Technical Information of China (English)

    陈宇

    1995-01-01

    A new Lagrangian method for studying the relationship between the energy velocity and the group velocity is described. It is proved that under the usual quasistatic electric field, the energy velocity is identical to the group velocity for acoustic waves in anisotropic piezoelectric (or non-piezoelectric) media.

  11. Polypropylene/Expanded Graphite/Carbon Fiber Thermal Conductive Composite%聚丙烯/膨胀石墨/碳纤维导热复合材料

    Institute of Scientific and Technical Information of China (English)

    徐睿杰; 雷彩红; 杨志广; 廖敦锃; 刘舜莉

    2012-01-01

    The thermal conductivity, mechanical properties and processing property of polypropylene ( PP)/expanded graphite (EG)/carbon fiber(CF) composite were studied. The results showed that the thermal conductivity of the composite with 20 % content of EC was 2 times that of pure PP,but its melt flow rate was decreased. The PE wax at the weight fraction of 1 % could improve the melt flow rate. When the content of carbon fiber was 5 % , the thermal conductivity reached 0.91 W ? M-1K-1 and was five times of pure PP. The melt flow rate was 1.72 g/10 min and the mechanical properties were good.%研究了聚丙烯(PP)/膨胀石墨(EG)/碳纤维(CF)复合材料的导热、力学以及加工性能.研究发现:当膨胀石墨的质量含量达到20%时,热导率是纯聚丙烯的2倍,但熔体流动性能有所下降;添加1%的聚乙烯蜡可以明显改善体系的熔体流动性能;将膨胀石墨与5%的碳纤维杂化使用,热导率达0.91 W·m-1K-1,是纯聚丙烯的5倍,熔体指数达到1.72 g/10 min,同时该复合材料具有较好的力学性能.

  12. Towards a novel bioelectrocatalytic platform based on “wiring” of pyrroloquinoline quinone-dependent glucose dehydrogenase with an electrospun conductive polymeric fiber architecture

    Science.gov (United States)

    Gladisch, Johannes; Sarauli, David; Schäfer, Daniel; Dietzel, Birgit; Schulz, Burkhard; Lisdat, Fred

    2016-01-01

    Electrospinning is known as a fabrication technique for electrode architectures that serve as immobilization matrices for biomolecules. The current work demonstrates a novel approach to construct a conductive polymeric platform, capable not only of immobilization, but also of electrical connection of the biomolecule with the electrode. It is produced upon electrospinning from mixtures of three different highly conductive sulfonated polyanilines and polyacrylonitrile on ITO electrodes. The resulting fiber mats are with a well-retained conductivity. After coupling the enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) to polymeric structures and addition of the substrate glucose an efficient bioelectrocatalysis is demonstrated. Depending on the choice of the sulfonated polyanilline mediatorless bioelectrocatalysis starts at low potentials; no large overpotential is needed to drive the reaction. Thus, the electrospun conductive immobilization matrix acts here as a transducing element, representing a promising strategy to use 3D polymeric scaffolds as wiring agents for active enzymes. In addition, the mild and well reproducible fabrication process and the active role of the polymer film in withdrawing electrons from the reduced PQQ-GDH lead to a system with high stability. This could provide access to a larger group of enzymes for bioelectrochemical applications including biosensors and biofuel cells.

  13. Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber-optic distributed thermal perturbation sensor

    Energy Technology Data Exchange (ETDEWEB)

    Freifeld, B.M.; Finsterle, S.; Onstott, T.C.; Toole, P.; Pratt, L.M.

    2008-10-10

    We have developed a borehole methodology to estimate formation thermal conductivity in situ with a spatial resolution of one meter. In parallel with a fiber-optic distributed temperature sensor (DTS), a resistance heater is deployed to create a controlled thermal perturbation. The transient thermal data is inverted to estimate the formation's thermal conductivity. We refer to this instrumentation as a Distributed Thermal Perturbation Sensor (DTPS), given the distributed nature of the DTS measurement technology. The DTPS was deployed in permafrost at the High Lake Project Site (67 degrees 22 minutes N, 110 degrees 50 minutes W), Nunavut, Canada. Based on DTPS data, a thermal conductivity profile was estimated along the length of a wellbore. Using the thermal conductivity profile, the baseline geothermal profile was then inverted to estimate a ground surface temperature history (GSTH) for the High Lake region. The GSTH exhibits a 100-year long warming trend, with a present-day ground surface temperature increase of 3.0 {+-} 0.8 C over the long-term average.

  14. Optical fiber modal noise in the 0.8 to 1.5 micron region and implications for near infrared precision radial velocity measurements

    CERN Document Server

    McCoy, Keegan; Mahadevan, Suvrath; Halverson, Samuel; Redman, Stephen L

    2012-01-01

    Modal noise in fibers has been shown to limit the signal-to-noise ratio achievable in fiber-coupled, high-resolution spectrographs if it is not mitigated via modal scrambling techniques. Modal noise become significantly more important as the wavelength increases and presents a risk to the new generation of near-infrared precision radial spectrographs under construction or being proposed to search for planets around cool M-dwarf stars, which emit most of their light in the NIR. We present experimental results of tests at Penn State University characterizing modal noise in the far visible out to 1.5 microns and the degree of modal scrambling we obtained using mechanical scramblers. These efforts are part of a risk mitigation effort for the Habitable Zone Planet Finder spectrograph currently under development at Penn State University.

  15. CURRENT STATUS AND PROSPECTS OF STUDY ON LOW VELOCITY IMPACT DAMAGED CHARACTERIZATION OF FIBER-REINFORCED COMPOSITE LAMINATES%FRP 层合板低速冲击损伤特性研究现状与展望

    Institute of Scientific and Technical Information of China (English)

    张颖军; 梅志远; 朱锡

    2011-01-01

    纤维增强复合材料层合板(FRP)由于具有比强度高、比模量高、可设计性强等特性,在工程领域得到越来越广泛的应用.但是低速冲击造成的损伤对层合板力学性能的影响非常显著,导致其强度和刚度下降.本文针对近年来纤维增强复合材料层合板低速冲击作用下的损伤研究进行了综述和回顾,重点介绍了试验研究方法、模拟计算研究方法、FRP 层合板损伤性能表征方法,并对有待于进一步研究的问题进行了展望.%Fiber-reinforced composite laminates have been widely used in engineering area because of its special properties, such as high specific strength, high specific stiffness and excellent designability. But the effect of damage caused by low velocity impact on the FRP is remarkable, which can reduce the strength and stiffness. The study on damage of fiber-reinforced composite laminates under low velocity impact in recent years is summarized and reviewed in this article. The main contents of the article are as follows: experimental methods, simulating and calculating methods, characterization of composites damage, and some problems to be studied in the future are proposed.

  16. Ground Wood Fiber Length Distributions

    OpenAIRE

    Lauri Ilmari Salminen; Sari Liukkonen; Alava, Mikko J.

    2014-01-01

    This study considers ground wood fiber length distributions arising from pilot grindings. The empirical fiber length distributions appear to be independent of wood fiber length as well as feeding velocity. In terms of mathematics the fiber fragment distributions of ground wood pulp combine an exponential distribution for high-length fragments and a power-law distribution for smaller lengths. This implies that the fiber length distribution is influenced by the stone surface. A fragmentation-ba...

  17. Cellulose-coupled graphene/polypyrrole composite electrodes containing conducting networks built by carbon fibers as wearable supercapacitors with excellent foldability and tailorability

    Science.gov (United States)

    Lyu, Shaoyi; Chang, Huanjun; Fu, Feng; Hu, La; Huang, Jingda; Wang, Siqun

    2016-09-01

    A paper-based wearable supercapacitor with excellent foldability and tailorability is fabricated from a chopped carbon fiber (CCF)-reinforced cellulose paper electrode material by coating with reduced graphene oxide (RGO) and polypyrrole (PPy) via in situ polymerization. The CCFs not only form an interpenetrating conducting network that acts as highly conductive electron transfer highways for the RGO/PPy layer in the paper electrode, but also endow the resulting electrode with an excellent areal capacitance of 363 mF cm-2 and a volumetric energy density of 0.28 mW h cm-3. Further, the CCFs give the electrode remarkable mechanical robustness, guaranteeing foldability and tailorability, with only slight loss of capacitance after repeated folding 600 times. Even after being subjected to severe cut-in fracture, the capacitance retention is up to 84%, indicating outstanding damage tolerance. The present study reveals a promising candidate for flexible wearable energy storage devices that are required to function in harsh environments.

  18. The crucial role of temperature in high-velocity weakening of faults : Experiments on gouge using host blocks with different thermal conductivities

    NARCIS (Netherlands)

    Yao, Lu; Ma, Shengli; Platt, John D.; Niemeijer, André R.; Shimamoto, Toshihiko

    We study the important role of temperature rise in the dynamic weakening of fault gouge at seismic slip rates by using host blocks composed of brass, stainless steel, titanium alloy, and gabbro with thermal conductivities (λh) of 123, 15, 5.8, and 3.25 W/m/K, respectively. Our experiments are

  19. Studies on transmission property changes of optical fibers inside an OPGW heated by conducting or discharge currents; OPGW tsuden/hoden kanetsu ni yoru hikari denso tokusei hendo no kento (sodensen kanshi hoho no chosa kenkyu)

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, I.; Seikai, S.; Takenaka, T. [Kansai Elecatric Power Co. Inc., Osaka (Japan)

    1999-09-30

    Temperature of OPGW's is known to increase due to thunderbolt. Therefore, the measurement of transmission characteristic changes of optical fibers inside the OPGW is seems to be useful method to supervise the electric power sending systems. Candidates for the detectable characteristics are optical loss, Brilloum frequency shift and Raman scattering power because distribution of these changes can be measured by OTDR techniques. In this experiments, those properties are investigated using a high voltage supply system at the Central Research Institute of Electric Power Industry. A test OPGW containing 24 fibers including 22 single-mode and 2 multi-mode fibers is installed with a span length of 20m. In the current conducting test, the OPGW is heated up to 250 degree C through three times conduction of 6kA with each duration time of 600 or 700ms. In the discharge current test, electric charge of 50C(coulomb), 100C and 200C with 20ms duration are applied. The results of the experiments are summarized as follows. The optical loss change is negligible small except for the fiber brake case and the Brilloum frequency shift is not always suitable because the sensitivity is small. The temperature measurement by the Raman scattering observation using the multi-mode fibers is found to have enough sensitivity and accuracy. However, residual problem is to increase the sensitivity of it for single mode fibers. (author)

  20. Fiber Optics Instrumentation Development

    Science.gov (United States)

    Chan, Patrick Hon Man; Parker, Allen R., Jr.; Richards, W. Lance

    2010-01-01

    This is a general presentation of fiber optics instrumentation development work being conducted at NASA Dryden for the past 10 years and recent achievements in the field of fiber optics strain sensors.

  1. Conduction velocity of the rabbit facial nerve: a noninvasive functional evaluation Velocidade de condução no nervo facial do coelho: uma avaliação funcional não invasiva

    Directory of Open Access Journals (Sweden)

    Belmiro Cavalcanti do Egito Vasconcelos

    2003-06-01

    Full Text Available The aim of this study was to evaluate standardized conduction velocity data for uninjured facial nerve and facial nerve repaired with autologous graft nerves and synthetic materials. An evaluation was made measuring the preoperative differences in the facial nerve conduction velocities on either side, and ascertaining the existence of a positive correlation between facial nerve conduction velocity and the number of axons regenerated postoperatively. In 17 rabbits, bilateral facial nerve motor action potentials were recorded pre- and postoperatively. The stimulation surface electrodes were placed on the auricular pavilion (facial nerve trunk and the recording surface electrodes were placed on the quadratus labii inferior muscle. The facial nerves were isolated, transected and separated 10 mm apart. The gap between the two nerve ends was repaired with autologous nerve grafts and PTFE-e (polytetrafluoroethylene or collagen tubes. The mean of maximal conduction velocity of the facial nerve was 41.10 m/s. After 15 days no nerve conduction was evoked in the evaluated group. For the period of 2 and 4 months the mean conduction velocity was approximately 50% of the normal value in the subgroups assessed. A significant correlation was observed between the conduction velocity and the number of regenerated axons. Noninvasive functional evaluation with surface electrodes can be useful for stimulating and recording muscle action potentials and for assessing the functional state of the facial nerve.O objetivo deste estudo foi avaliar os dados padronizados de velocidade de condução para o nervo facial não lesado e o nervo facial reparado com enxerto autógeno e com materiais sintéticos. Na avaliação foram medidas as diferenças pré-operatórias de velocidade de condução do nervo facial em cada lado e verificada a existência de uma correlação positiva entre a velocidade de condução do nervo facial e o número de axônios regenerados no p

  2. Polymer optical fiber fuse

    CERN Document Server

    Mizuno, Yosuke; Tanaka, Hiroki; Nakamura, Kentaro

    2013-01-01

    Although high-transmission-capacity optical fibers are in demand, the problem of the fiber fuse phenomenon needs to be resolved to prevent the destruction of fibers. As polymer optical fibers become more prevalent, clarifying their fuse properties has become important. Here, we experimentally demonstrate a fuse propagation velocity of 21.9 mm/s, which is 1 to 2 orders of magnitude slower than that in standard silica fibers. The achieved threshold power density and proportionality constant between the propagation velocity and the power density are respectively 1/186 of and 16.8 times the values for silica fibers. An oscillatory continuous curve instead of periodic voids is formed after the passage of the fuse. An easy fuse termination method is presented herein, along with its potential plasma applications.

  3. Anastomose do nervo facial de coelhos com cola de fibrina: estudo da velocidade de condução nervosa Rabbit facial nerve anastomosis with fibrin glue: nerve conduction velocity evaluation

    Directory of Open Access Journals (Sweden)

    Francisco Aurelio Lucchesi Sandrini

    2007-04-01

    Full Text Available OBJETIVO: Este estudo tem o objetivo de avaliar através da velocidade de condução nervosa com eletrodos de superfície a utilização da cola de fibrina na anastomose nervosa. MÉTODOS: Neste experimento, foram avaliadas as diferenças entre as velocidades de condução nervosa pré e pós-operatória do nervo facial esquerdo de 12 coelhos. Foi verificada a existência de correlação entre a velocidade de condução nervosa e o número de axônios regenerados no pós-operatório. Os nervos transeccionados foram unidos com cola de fibrina. O potencial de ação motora foi obtido com o uso de eletrodos de superfície. O eletrodo de estimulação foi colocado imediatamente à frente do pavilhão auditivo (tronco do nervo facial e o eletrodo de gravação foi colocado no músculo quadrado do lábio inferior. RESULTADOS: A média normal da velocidade de condução nervosa foi de 36,53 m/seg. Ao final do período, a velocidade de condução nervosa atingiu um valor de aproximadamente 81% do valor normal. Não foi observada correlação significativa entre a velocidade de condução nervosa pós-operatória e o número de axônios regenerados (p=0,146. CONCLUSÃO: A anastomose com cola de fibrina pode ser utilizada para anastomose nervosa no modelo animal e nervo estudados.AIM: The aim of this study was to evaluate the use of fibrin glue on nerve anastomosis, and study conduction velocity obtained by surface electrodes. METHODS: In this experimental model we evaluated nerve conduction velocity differences in the preoperative and postoperative periods, for the left facial nerve of 12 rabbits. Then, we evaluated whether there were correlations between conduction velocity and the number of postoperative regenerated axons. The sectioned nerves were anastomosed with fibrin glue. The muscle action potentials were obtained from surface electrodes. The stimulation electrode was placed immediately before the ear pinna (facial nerve trunk and the recording

  4. Particle deposition in a realistic geometry of the human conducting airways: Effects of inlet velocity profile, inhalation flowrate and electrostatic charge.

    Science.gov (United States)

    Koullapis, P G; Kassinos, S C; Bivolarova, M P; Melikov, A K

    2016-07-26

    Understanding the multitude of factors that control pulmonary deposition is important in assessing the therapeutic or toxic effects of inhaled particles. The use of increasingly sophisticated in silico models has improved our overall understanding, but model realism remains elusive. In this work, we use Large Eddy Simulations (LES) to investigate the deposition of inhaled aerosol particles with diameters of dp=0.1,0.5,1,2.5,5 and 10μm (particle density of 1200kg/m(3)). We use a reconstructed geometry of the human airways obtained via computed tomography and assess the effects of inlet flow conditions, particle size, electrostatic charge, and flowrate. While most computer simulations assume a uniform velocity at the mouth inlet, we found that using a more realistic inlet profile based on Laser Doppler Anemometry measurements resulted in enhanced deposition, mostly on the tongue. Nevertheless, flow field differences due to the inlet conditions are largely smoothed out just a short distance downstream of the mouth inlet as a result of the complex geometry. Increasing the inhalation flowrate from sedentary to activity conditions left the mean flowfield structures largely unaffected. Nevertheless, at the higher flowrates turbulent intensities persisted further downstream in the main bronchi. For dp>2.5μm, the overall Deposition Fractions (DF) increased with flowrate due to greater inertial impaction in the oropharynx. Below dp=1.0μm, the DF was largely independent of particle size; it also increased with flowrate, but remained significantly lower. Electrostatic charge increased the overall DF of smaller particles by as much as sevenfold, with most of the increase located in the mouth-throat. Moreover, significant enhancement in deposition was found in the left and right lung sub-regions of our reconstructed geometry. Although there was a relatively small impact of inhalation flowrate on the deposition of charged particles for sizes dp<2.5μm, impaction prevailed over

  5. Correlation between body composition and nerve conduction velocity in patients with type 2 diabetes mellitus%2型糖尿病患者人体成分与神经传导速度的相关性分析

    Institute of Scientific and Technical Information of China (English)

    顾婷; 姜博仁; 任荣亮; 陆颖理; 乔洁

    2013-01-01

    Objective To investigate the correlation between body composition and nerve conduction velocity in patients with type 2 diabetes mellitus.Methods One hundred and five patients with type 2 diabetes mellitus were enrolled,body composition related parameters including body mass index,body fat percent,body muscle percent and body water percent were measured by body composition analyzer,nerve conduction velocity related parameters including motor nerve conduction velocity,distal motor latency,amplitude of compound muscle action potential,sensory nerve conduction velocity,latency and amplitude of sensory nerve action potential were determined,and the correlation between body composition and nerve conduction velocity was explored.Results Body fat percent was positively correlated with nerve conduction velocity of motor-sensory ulnar nerve and motor peroneal nerve,and negatively correlated with distal latency of sensory ulnar nerve,sensory superficial peroneal nerve,motor peroneal nerve and motor amplitude of peroneal nerve.Body muscle percent was positively correlated with distal latency of sensory ulnar nerve,sensory superficial peroneal nerve,motor peroneal nerve and motor amplitude of peroneal nerve,and negatively correlated with nerve conduction velocity of motor-sensory ulnar nerve and motor peroneal nerve.Body water percent was positively correlated with distal latency of sensory ulnar nerve and sensory superficial peroneal nerve,and negatively correlated with nerve conduction velocity of sensory ulnar nerve.Body mass index and waist circumference were negatively correlated with sensory amplitude of median nerve and motor amplitude of tibial nerve.Conclusion Body mass index,waist circumference,body fat percent,body muscle percent and body water percent may be important influencing factors of nerve conduction velocity.%目的 分析2型糖尿病患者人体成分与神经传导速度的相关性.方法 选取105例2型糖尿病患者作为研究对象,使用身体

  6. Research Progress on Thermal Conductivity of Carbon Fiber Reinforced Polymer Matrix Composites%导热型碳纤维增强聚合物基复合材料的研究进展

    Institute of Scientific and Technical Information of China (English)

    李仕通; 彭超义; 邢素丽; 肖加余

    2012-01-01

    The present state and development of thermal conductivity of carbon fiber reinforced polymer matrix composites (CFRP) are reviewed. Phonon and photon thermal conduction mechanism of CFRP are described. The computing models and testing methods for the thermal conductivity of CFRP, prepared by different ply angles and different packing fractions, are illustrated. The effects of the resin systems (including epoxy resin, cyanate ester, bisma-leimide resin), carbon fibers (including PAN carbon fibers, mesophase pitch carbon fibers, vapor grown carbon fibers, carbon nanotube fibers), processing technologies etc. on the thermal conductivity of CFRP are also analyzed.%综述了导热型连续碳纤维增强聚合物基复合材料(CFRP)的研究与应用现状和进展,阐述了CFRP的声子导热和光子导热机理,介绍了不同铺层角度和铺层比的CFRP面内和厚度方向热导率计算模型及测试方法,分析了环氧树脂、氰酸酯、双马来酰亚胺等3类树脂体系和聚丙烯腈基(PAN)碳纤维、中间相沥青基碳纤维、气相生长碳纤维、碳纳米管纤维等4类增强体以及工艺方法等因素对CFRP热导率的影响.

  7. A novel anaerobic electrochemical membrane bioreactor (AnEMBR) with conductive hollow-fiber membrane for treatment of low-organic strength solutions

    KAUST Repository

    Katuri, Krishna

    2014-11-04

    A new anaerobic treatment system that combined a microbial electrolysis cell (MEC) with membrane filtration using electrically conductive, porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to treat low organic strength solution and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode for hydrogen evolution reaction (HER) and the membrane for filtration of the effluent. The AnEMBR system was operated for 70 days with synthetic acetate solution having a chemical oxygen demand (COD) of 320 mg/L. Removal of COD was >95% at all applied voltages tested. Up to 71% of the substrate energy was recovered at an applied voltage of 0.7 V as methane rich biogas (83% CH4; < 1% H2) due to biological conversion of the hydrogen evolved at the cathode to methane. A combination of factors (hydrogen bubble formation, low cathode potential and localized high pH at the cathode surface) contributed to reduced membrane fouling in the AnEMBR compared to the control reactor (open circuit voltage). The net energy required to operate the AnEMBR system at an applied voltage of 0.7 V was significantly less (0.27 kWh/m3) than that typically needed for wastewater treatment using aerobic membrane bioreactors (1-2 kWh/m3).

  8. Numerical Simulation of Thermal Conductivity of Carbon-fiber/Resin Composites%炭纤维/树脂复合材料导热性能的数值模拟

    Institute of Scientific and Technical Information of China (English)

    胡妞; 李布楠; 高本征

    2014-01-01

    采用有限元方法对炭纤维/树脂复合材料的导热性能进行了数值模拟,分别建立一维结构和二维结构炭纤维/树脂复合材料计算分析模型,研究炭纤维含量、界面接触热阻、以及炭纤维直径对复合材料有效热导率的影响。研究结果表明炭纤维作为复合材料增强相,其含量越高复合材料的热导率越高;界面的接触热阻在10-3~10-5(m2 K)/W范围内对复合材料有效热导率有较大的影响,超出范围之后改变接触热阻对材料热导率的影响可以忽略;接触热阻比较大时,炭纤维的直径对复合材料的热导率有较大的的影响,当接触热阻比较小时,炭纤维的直径对于复合材料热导率的影响非常小。%Thermal conductivity of carbon-fiber/resin composites was simulated by finite element method. Simulation models of one-dimensional structure and two-dimensional structure were respectively built. Effects of carbon fiber content, interface contact resistance and diameter of carbon fiber on effective thermal conductivity of carbon-fiber/resin composite were studied. The results show that thermal conductivity of carbon-fiber /resin composites increases with increasing of carbon fiber volume fraction;the interface contact resistance in the range of 10-3~10-5 m2 K/W has obvious influence on the effective thermal conductivity, while out of range, the influence can be ignored; the diameter of carbon fiber has a remarkable influence on the thermal conductivity when the interface contact resistance is larger, but the influence is very small when the interface contact resistance is lesser.

  9. Non-conductive and miniature fiber-optic imaging system for real-time detection of neuronal activity in time-varying electromagnetic fields.

    Science.gov (United States)

    Saito, Atsushi; Takahashi, Masayuki; Jimbo, Yasuhiko; Nakasono, Satoshi

    2017-01-15

    Establishing an appropriate threshold value for neuronal modulation by time-varying electromagnetic field (EMF) exposure is important for developing international guidelines to protect against the potential health effects, and to design a variety of medical devices. However, it is technically difficult to achieve real-time detection of neuronal activity under repetitive and long-term exposure to EMF. For this purpose, we developed a non-conductive, miniature, and flexible fiber-optic imaging system that does not affect the electromagnetic noise, induction heating, or vibration in a high-intensity and repetitive time-varying EMF exposure. Using the proposed system, we succeeded at real-time detection of spontaneous Ca(2+) oscillations in single neuronal and glial cells, as well as synchronized bursting activities of multiple neuronal networks at a micrometer-scale and millisecond-order spatiotemporal resolution during long-term EMF exposure (sinusoidal wave, 20kHz, 8.6mT, >30min). The results indicated that short-term (exposure-related neuronal modulation was not detectable; however, long-term (15-30min) exposure was observed to depress neuronal activities. In addition, the simultaneous and real-time recording of neuronal activity and the environmental temperature revealed that the neuronal modulation was accompanied by a 0.5-1°C rise in the temperature of the culture medium induced by the heat generation of exposure coils. These findings suggest that our real-time imaging system can be used for precise evaluation of the threshold values and clarification of the mechanisms of neuronal modulation induced by time-varying EMF exposure.

  10. Use of optical fibers in spectrophotometry

    Science.gov (United States)

    Ramsey, Lawrence W.

    1988-01-01

    The use of single or small numbers of fiber optic fibers in astronomical spectroscopy with the goal of greater spectrophotometric and radial velocity accuracy is discussed. The properties of multimode step index fibers which are most important for this application are outlined, as are laboratory tests of currently available fibers.

  11. Development of the experimental procedure to examine the response of carbon fiber-reinforced polymer composites subjected to a high-intensity pulsed electric field and low-velocity impact.

    Science.gov (United States)

    Hart, Robert J; Zhupanska, Olesya I

    2016-01-01

    A new fully automated experimental setup has been developed to study the response of carbon fiber reinforced polymer (CFRP) composites subjected to a high-intensity pulsed electric field and low-velocity impact. The experimental setup allows for real-time measurements of the pulsed electric current, voltage, impact load, and displacements on the CFRP composite specimens. The setup includes a new custom-built current pulse generator that utilizes a bank of capacitor modules capable of producing a 20 ms current pulse with an amplitude of up to 2500 A. The setup enabled application of the pulsed current and impact load and successfully achieved coordination between the peak of the current pulse and the peak of the impact load. A series of electrical, impact, and coordinated electrical-impact characterization tests were performed on 32-ply IM7/977-3 unidirectional CFRP composites to assess their ability to withstand application of a pulsed electric current and determine the effects of the pulsed current on the impact response. Experimental results revealed that the electrical resistance of CFRP composites decreased with an increase in the electric current magnitude. It was also found that the electrified CFRP specimens withstood higher average impact loads compared to the non-electrified specimens.

  12. Development of the experimental procedure to examine the response of carbon fiber-reinforced polymer composites subjected to a high-intensity pulsed electric field and low-velocity impact

    Science.gov (United States)

    Hart, Robert J.; Zhupanska, Olesya I.

    2016-01-01

    A new fully automated experimental setup has been developed to study the response of carbon fiber reinforced polymer (CFRP) composites subjected to a high-intensity pulsed electric field and low-velocity impact. The experimental setup allows for real-time measurements of the pulsed electric current, voltage, impact load, and displacements on the CFRP composite specimens. The setup includes a new custom-built current pulse generator that utilizes a bank of capacitor modules capable of producing a 20 ms current pulse with an amplitude of up to 2500 A. The setup enabled application of the pulsed current and impact load and successfully achieved coordination between the peak of the current pulse and the peak of the impact load. A series of electrical, impact, and coordinated electrical-impact characterization tests were performed on 32-ply IM7/977-3 unidirectional CFRP composites to assess their ability to withstand application of a pulsed electric current and determine the effects of the pulsed current on the impact response. Experimental results revealed that the electrical resistance of CFRP composites decreased with an increase in the electric current magnitude. It was also found that the electrified CFRP specimens withstood higher average impact loads compared to the non-electrified specimens.

  13. Temperature dependence of the thermal conductivity of individual pitch-derived carbon fibers%单根沥青基炭纤维热导率的温度特性研究

    Institute of Scientific and Technical Information of China (English)

    王建立; 顾明; 马维刚; 张兴; 宋燕

    2008-01-01

    The thermal conductivity of individual pitch-derived carbon fibers was measured in the temperature range 100-400 K by a T type method, in which a hot wire served both as a heating source and thermometer, and the electrical and thermal properties of the hot wire were measured by direct current heating. When a tested carbon fiber was attached to the center position of the hot wire, the thermal conductivity of the fiber was determined by a comparison of the ave-rage temperature rise of the hot wire with and without the fiber. Results show that the thermal conductivity of the fiber was limited by boundary scattering below 300K, and saturated around 350K at a value of about 800W/(m·K). An un-expectedly high thermal conductivity of about 920W/(m·K) was observed at around 400 K. The effect of the thermal contact resistance on the measurement was estimated by changing the length of the fiber in the same contact conditions and the radiation effect was also discussed. The uncertainty of the thermal conductivity was estimated to be±13%.%采用"T"形法测量了温度100K~400K范围内单根沥青基炭纤维的热导率.结果表明,在300K以下,由于边界散射的影响,炭纤维热导率随着温度升高而增大,350K左右渐趋于饱和,对应热导率约为800W/(in·K),400K附近热导率又增大至920W/(in·K).在不改变接触点的前提下,通过测量同一根纤维小同长度对应的热导率,估计了炭纤维与热线节点处的接触热阻,并讨论了不同温度下辐射对热导率测量的影响,最后得到热导率的测量不确定度在±13%以内.

  14. 玻璃纤维铝合金板低速冲击损伤演化数值模拟%Numerical simulation of damage evolution on low-velocity impact of glass fiber reinforced aluminum laminates

    Institute of Scientific and Technical Information of China (English)

    万云; 章继峰; 周利民; 王振清

    2015-01-01

    编写了复合材料损伤的VUMAT子程序,并结合Johnson‐Cook金属损伤模型和表面内聚力行为层间分层方法建立了玻璃纤维增强铝合金层板(GLARE)受落锤低速冲击的数值模型。分析了能量吸收、形变情况及锤头接触力的变化,并通过与实验结果的比较验证了有限元方法的可靠性。利用有限元方法能够更全面分析材料损伤变化的优势,模拟了GLARE三维渐进失效、铝合金层的失效以及纤维层和铝合金层界面分层的破坏模式。通过综合分析该三种渐进失效与能量吸收、形变情况及锤头接触力的变化,揭示了玻璃纤维增强铝合金层板受落锤低速冲击下的破坏机理,验证了铝合金层板的加入对于玻璃纤维增强铝合金层板抗冲击性能增强规律。%A numerical methodology including user material subroutine VUMAT (vectorizd user mate‐rial routine) for composite material ,Johnson‐Cook flow stress model and surface‐based cohesive be‐havior for interface delamination analysis were carried out to simulate the history of absorbing energy , central deflection and contact force during low‐velocity impact of GLARE (glass reinforced aluminun laminates) plate .After the comparison between the experimental and simulative results ,the numeri‐cal methodology was proved right and feasible .Moreover ,numerical simulation had advantages in rounded analysis in the damage of material .T he damage progression of fiber reinforced layers ,alumi‐num alloy layers and delamination in GLARE were analyzed ,respectively .After comparing and analy‐zing three kinds of damage evolution and the curve of history of absorbing energy ,central deflection and contact force ,simulation results show that aluminum alloy layers play an important role in in‐creasing the performance of low‐velocity impact for composites material .

  15. Oxidation of Carbon Fibers in Water Vapor Studied

    Science.gov (United States)

    Opila, Elizabeth J.

    2003-01-01

    T-300 carbon fibers (BP Amoco Chemicals, Greenville, SC) are a common reinforcement for silicon carbide composite materials, and carbon-fiber-reinforced silicon carbide composites (C/SiC) are proposed for use in space propulsion applications. It has been shown that the time to failure for C/SiC in stressed oxidation tests is directly correlated with the fiber oxidation rate (ref. 1). To date, most of the testing of these fibers and composites has been conducted in oxygen or air environments; however, many components for space propulsion, such as turbopumps, combustors, and thrusters, are expected to operate in hydrogen and water vapor (H2/H2O) environments with very low oxygen contents. The oxidation rate of carbon fibers in conditions representative of space propulsion environments is, therefore, critical for predicting component lifetimes for real applications. This report describes experimental results that demonstrate that, under some conditions, lower oxidation rates of carbon fibers are observed in water vapor and H2/H2O environments than are found in oxygen or air. At the NASA Glenn Research Center, the weight loss of the fibers was studied as a function of water pressure, temperature, and gas velocity. The rate of carbon fiber oxidation was determined, and the reaction mechanism was identified.

  16. Radial Velocities with PARAS

    Science.gov (United States)

    Roy, Arpita; Mahadevan, S.; Chakraborty, A.; Pathan, F. M.; Anandarao, B. G.

    2010-01-01

    The Physical Research Laboratory Advanced Radial-velocity All-sky Search (PARAS) is an efficient fiber-fed cross-dispersed high-resolution echelle spectrograph that will see first light in early 2010. This instrument is being built at the Physical Research laboratory (PRL) and will be attached to the 1.2m telescope at Gurushikhar Observatory at Mt. Abu, India. PARAS has a single-shot wavelength coverage of 370nm to 850nm at a spectral resolution of R 70000 and will be housed in a vacuum chamber (at 1x10-2 mbar pressure) in a highly temperature controlled environment. This renders the spectrograph extremely suitable for exoplanet searches with high velocity precision using the simultaneous Thorium-Argon wavelength calibration method. We are in the process of developing an automated data analysis pipeline for echelle data reduction and precise radial velocity extraction based on the REDUCE package of Piskunov & Valenti (2002), which is especially careful in dealing with CCD defects, extraneous noise, and cosmic ray spikes. Here we discuss the current status of the PARAS project and details and tests of the data analysis procedure, as well as results from ongoing PARAS commissioning activities.

  17. Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete

    OpenAIRE

    Weimin Song; Jian Yin

    2016-01-01

    Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%,...

  18. Simulation of propagation in a bundle of skeletal muscle fibers: Modulation effects of passive fibers

    DEFF Research Database (Denmark)

    Henneberg, Kaj-åge; F.A., Roberge

    1997-01-01

    source current (I-ma) enters the passive tissue as a radial load current (I-ep) while the rest flows longitudinally in the cleft between the active and adjacent passive fibers. The conduction velocity of 1.32 m/s was about 30% lower than on an isolated fiber in a Ringer bath, in close agreement...... rate of rise of the action potential upstroke (V-max) from 512 to 503 V/s. Increasing the phase angle of the passive fiber membrane impedence (Z(m)) increases the phase delay between I-ma and I-ep, thereby increasing phi(epp) which in turn slows down propagation and increases V-max....

  19. 聚合物/镀镍碳纤维导电复合材料的研究进展%Research Development of Polymer/Nickel-Coated Carbon Fiber Conductive Composites

    Institute of Scientific and Technical Information of China (English)

    陈彤; 薛平; 贾明印; 韩宇

    2014-01-01

    综述了聚合物/镀镍碳纤维(NiCF)导电复合材料的优点及其导电机理,介绍了该种导电复合材料的几种制备方法,包括单螺杆挤出机法、双螺杆挤出机法、密炼机法和Brabender塑化仪法,并详细地分析和总结了影响聚合物/NiCF导电复合材料导电性的NiCF长度、表面改性与分散、填充量以及加工工艺等因素。%The advantages and conductive mechanism of polymer/nickel-coated carbon fiber conductive composites were reviewed. The several preparation methods of the kind of conductive composites were introduced,which include single-screw extruder,twin-screw extruder,mixer method and Brabender plasti-corder. The effects such as the length,surface treatment and dispersion,addition amounts of the nickel-coated carbon fiber and processing technology on the conductivity of the conductive composites were discussed and summarized.

  20. 短切PAN基碳纤维导电沥青混合料性能试验研究%Experimental research on performances for conductive asphalt mixture with chopped PAN-based carbon fiber

    Institute of Scientific and Technical Information of China (English)

    查旭东; 陈勇强; 程景

    2012-01-01

    In order to determine a reasonable carbon fiber contents for the conductive asphalt mixture with carbon fiber,the chopped polyacrylonitrile(PAN) based carbon fiber was selected as a conductive phase material.Many laboratory experiments were conducted to analyze the effect of the carbon fiber contents on the Marshall performances and the conductive performances for the AC-13C of conductive asphalt mixture and then verify its pavement performances.The results show that,under the same asphalt-aggregate ratio,with the increases of the carbon fiber contents,the bulk volume density,the voids filled with asphalt and the Marshall stability of the conductive asphalt mixture are appeared the trend from increasing to decreasing,the volume of air voids and the voids in mineral aggregate are changed as the relation from decreasing to increasing,but the flow value is increased continuously.The technical standards of AC,adjustment and SMA were applied to the asphalt mixtures with the different ranges of carbon fiber content,respectively,and the reasonable optimal asphalt-aggregate ratios were determined.There is a good semilogarithm correlation between the optimal asphalt-aggregate ratios and the carbon fiber contents.Under the optimal asphalt-aggregate ratio,a good correlation of power function is showed between the logarithms of electrical resistivity and the carbon fiber contents for the conductive asphalt mixture.All the pavement performances of asphalt mixture with 0.1% of carbon fiber content have attained the technical requirements of modified asphalt mixture and SMA in the climate conditions with high demand.Therefore,the suitable carbon fiber content can play an excellent role in reinforcing the conductive asphalt mixture and then form the stable conductive network.The technical requirements of various performances and conductive heating are integrated to recommend the suitable carbon fiber content as 0.1%.%为了确定碳纤维导电沥青混合料的合理碳纤

  1. Characteristics of Angora rabbit fiber using optical fiber diameter analyzer.

    Science.gov (United States)

    Rafat, S A; de Rochambeau, H; Brims, M; Thébault, R G; Deretz, S; Bonnet, M; Allain, D

    2007-11-01

    An experiment was conducted to describe the characteristics of Angora rabbit fiber using optical fiber diameter analyzer (OFDA). A total of 349 fleece samples were collected from 60 French Angora rabbits. Recorded measurements of OFDA were as follows: mean fiber diameter, CV of fiber diameter, comfort factor, spinning fineness, mean fiber curvature, SD of fiber curvature, mean opacity of fibers, percentage of medullated fibers, mean fiber diameter along the length, and SD of fiber diameter along the length. Comfort factor is the percentage of fibers less than or equal to 30 microns. The main effects included in the mixed model were fixed effects of group, harvest season, and age and a random effect of animal. Correlations among total fleece weight, compression, and OFDA measurements were calculated. Mean fiber diameter was lower than the fiber diameter along the length. Mean percentage of medullated fibers was very low and ranged from 0.1 to 7.3%. The mean comfort factor was 97.5% and ranged from 93.3 to 99.8%. The mean fiber curvature was 40.1 degrees/mm. The major changes in Angora fleece characteristics from 8 to 105 wk of age were an increase in fiber diameter, CV of fiber diameter, mean fiber diameter along the length and curvature, and a decrease in compression and comfort factor. The effect of harvest season was significant on some fiber characteristics. Mean fiber diameter and the mean fiber diameter along the length had a positive correlation with total fleece weight. The OFDA methodology is a method to evaluate fiber diameter, CV of fiber diameter, and bristle content through measuring of the comfort factor. However, OFDA is not adapted for measuring opacity or size of the medulla, or both, in Angora wool and needs a new definition or a special calibration. The spinning fineness should be redefined and adapted for Angora rabbits.

  2. Ground Wood Fiber Length Distributions

    Directory of Open Access Journals (Sweden)

    Lauri Ilmari Salminen

    2014-01-01

    Full Text Available This study considers ground wood fiber length distributions arising from pilot grindings. The empirical fiber length distributions appear to be independent of wood fiber length as well as feeding velocity. In terms of mathematics the fiber fragment distributions of ground wood pulp combine an exponential distribution for high-length fragments and a power-law distribution for smaller lengths. This implies that the fiber length distribution is influenced by the stone surface. A fragmentation-based model is presented that allows reproduction of the empirical results.

  3. Preparation and Performance of PAN-based Carbon Fiber Conductive Asphalt Concrete%PAN基碳纤维导电沥青混凝土的制备及性能

    Institute of Scientific and Technical Information of China (English)

    冯新军; 查旭东; 程景

    2012-01-01

    In order to prepare conductive asphalt concrete for melting ice and snow on road surface,preparation and performance of PAN-based carbon fiber conductive asphalt concrete were studied.Through resistivity test of Marshall specimen,chopped length of PAN-based carbon fiber was determined.After the mixing test and Marshall compaction test of asphalt mixture,mixing techniques of PAN-based carbon fiber conductive asphalt concrete was put forward.The optimal oil-stone rate of PAN-based carbon fiber conductive asphalt concrete was determined with Marshall test design method,and the technical standards were adjusted according to their structural characteristics.Through tests of resistivity,rutting,trabecular bending,immersion Marshall and freezing-thawing splitting,variation laws of conductive properties and pavement performance with PAN-based carbon fiber quality fraction of conductive asphalt concrete were analyzed.The results show that conductive asphalt concrete with 0.1% PAN-based carbon fiber quality fraction has excellent conductive properties and pavement performance.%为制备能够融冰化雪的导电沥青混凝土,对聚丙烯腈(PAN)基碳纤维导电沥青混凝土的制备及性能进行了研究。通过沥青混合料马歇尔试件的电阻率测试试验,确定了碳纤维的短切长度。通过沥青混合料拌和试验和马歇尔击实试验,提出了导电沥青混合料的拌和工艺。采用马歇尔试验配合比设计方法,根据导电沥青混合料的结构特征调整了技术标准,确定了导电沥青混合料的最佳油石比。通过电阻率试验、车辙试验、小梁低温弯曲试验、浸水马歇尔试验和冻融劈裂试验,分析了导电沥青混合料的导电性能和路用性能随碳纤维掺量的变化规律。结果表明:当PAN基碳纤维掺量(质量分数)取0.1%时,导电沥青混凝土既可以获得优良的导电性能,也可以获得优良的路用性能。

  4. 补气通络方对大鼠周围神经传导速度恢复的影响%Effect of buqi tongluo prescription on recovery of peripheral nerve conduction velocity of rats

    Institute of Scientific and Technical Information of China (English)

    姚珍松; 梁德; 何振辉

    2006-01-01

    BACKGROUND: Buqi tongluo prescription, which is characterized by invigorating qi and promoting blood circulation, dredging collaterals and dispersing stagnation, promoting tissue regeneration, and promoting blood circulation to remove obstruction in the collateral, can promote blood circulation at local injured part and ameliorate nutrien of nerve so as to accelerate axonal regeneration of peripheral nerve and functional recovery of nerve conduction.OBJECTIVE: To observe the effect of buqi tongluo prescription of various agents on recovery of nerve function after peripheral nerve injury and compare the results with the combination of vitamin B1 and B6.DESIGN: Randomized controlled animal study.SETTING: Department of Orthopaedics of the First Hospital Affiliated to Guangzhou University of Traditional Chinese Medicine.MATERIALS: A total of 48 Wistar rats of confined clean grade were selected in this study. After modeling on right sciatic nerve, rats were randomly divided into buqi tongluo capsule group, buqi tongluo parenteral solution group, vitamin group and blank group with 12 in each group.METHODS: All rats were cut their right sciatic nerve laterally, and then anastomosis in situ was used immediately to establish models of peripheral nerve injury. Administration began on the third day after operation once a day. ① Rats in buqi tongluo capsule group were perfused with powder of buqi tongluo capsule (including huangqi, renshen, danggui, chuanxiong and danshen which was diluted with saline) of 0.9 g/(kg·d) raw drugs (ig). ② Rats in buqi tongluo parenteral solution group were injected with 0.9 g/(kg·d) buqi tongluo parenteral solution (ip). ③ Rats in vitamin group were perfused with 15 mg/(kg·d) suspension (1.5 g/L) of vitamin B1 and B6.④ Rats in blank group were perfused with 0.01 mL/g saline.MAIN OUTCOME MEASURES: Four rats from each group were selected for 4, 8 and 12 week time points after administration to record bilateral nerve conduction velocity

  5. 银沉积导电锦纶的制备工艺%Preparation of electroless silver deposited conductive nylon fiber

    Institute of Scientific and Technical Information of China (English)

    崔旭; 张华鹏; 陈建勇; 谢玉福

    2011-01-01

    Electroless silver deposition process was adopted to coat metal on the surface of the nylon fiber. The effects of deposition conditions on the structure and properties of the silver coated nylon fiber was studied. The morphology, elements and crystal structure of the deposited layer were characterized by FESEM, EDS, XRD, and the surface resistivity and adhesive force of the deposited layer to the fiber surface were measured. According to the analysis of above findings, the optimum deposition conditions were obtained, and the surface resistivity of the silver deposited nylon fiber was 0. 14 Ω/cm. The silver coater layer was compact, uniform and continuous. After washing 25 times, the weight loss of the silver coated nylon fiber was 1.5 %, and the surface resistivity increased to 0.24 Ω/cm.%采用化学液相银沉积法在锦纶纤维表面沉积银金属,实现锦纶纤维的表面金属化,探讨沉积条件对锦纶纤维结构与性能的影响.借助FESEM、EDS、XRD对银沉积后锦纶纤维的表面形貌、沉积层元素以及晶体结构进行了分析,测试了银沉积后纤维增重率、表面电阻及沉积层的结合牢度.在上述分析基础上,得出了锦纶纤维表面银沉积的最佳配方,得到的银沉积锦纶纤维的表面电阻为0.14 Ω/cm,银沉积层致密、均匀、连续.25次洗涤后纤维失重率为1.5%,表面电阻增至0.24 Ω/cm.

  6. The Re-sampling Technique Application in Action Potential Conduction Velocity Estimation of Surface Electromyography%基于重采样技术的肌电信号动作电位传导速度估计研究

    Institute of Scientific and Technical Information of China (English)

    付聪; 练士龙; 李强

    2011-01-01

    目的:本文针对表面肌电(sEMG)信号探讨动作电位传导速度(APCV)估计问题.方法:以生理学仿真sEMG信号为基础,采用基于互相关分析的时延估计技术来获取相应的APCV估计值,并利用重采样技术来提高估计的精度.结果:实验表明,针对重采样后的仿真信号,其APCV的估计误差得到了明显降低.结论:所采用方法能够有效获取满意的APCV估计效果.%Objective: The action potential conduction velocity (APCV) estimation was explored in this paper. Methods: Based on a physiological model of sEMG signal, the APCV estimation result was acquired by using the time-delay estimation of cross correlation, and the re-sampling technique was utilized to improve the estimation performance. Results: The experimental results showed that the APCV estimation error could be reduced by the re-sampling technique. Conclusion: The APCV estimation performance could be satisfac torily acquired by the proposed method.

  7. Prediction of Pseudo relative velocity response spectra at Yucca Mountain for underground nuclear explosions conducted in the Pahute Mesa testing area at the Nevada testing site; Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.S.

    1991-12-01

    The Yucca Mountain Site Characterization Project (YMP), managed by the Office of Geologic Disposal of the Office of Civilian Radioactive Waste Management of the US Department of Energy, is examining the feasibility of siting a repository for commercial, high-level nuclear wastes at Yucca Mountain on and adjacent to the Nevada Test Site (NTS). This work, intended to extend our understanding of the ground motion at Yucca Mountain resulting from testing of nuclear weapons on the NTS, was funded by the Yucca Mountain project and the Military Applications Weapons Test Program. This report summarizes one aspect of the weapons test seismic investigations conducted in FY88. Pseudo relative velocity response spectra (PSRV) have been calculated for a large body of surface ground motions generated by underground nuclear explosions. These spectra have been analyzed and fit using multiple linear regression techniques to develop a credible prediction technique for surface PSRVs. In addition, a technique for estimating downhole PSRVs at specific stations is included. A data summary, data analysis, prediction development, prediction evaluation, software summary and FORTRAN listing of the prediction technique are included in this report.

  8. Nanotailored Carbon Fibers

    Science.gov (United States)

    2012-04-27

    precursor fiber and also utilize bi- component spinning along with gel spinning, to obtain small diameter fibers. Various processing parameters during...shape of the fiber. In this regard, we have also conducted single component gel spinning using different gelation bath temperatures (100% methanol). SEM...domestic dishwashing detergent, Palmolive antibacterial , 3 wt% detergent and 97% water) for about a week and retested. *** For 5th trial, tungsten

  9. Study on the Properties of HDPE/Graphite/Carbon Fiber Thermal Conductivity Composite%高密度聚乙烯/石墨/碳纤维导热复合材料性能的研究

    Institute of Scientific and Technical Information of China (English)

    冯博; 冷金华; 陈弦; 何波兵

    2013-01-01

    采用高密度聚乙烯(HDPE)、石墨、碳纤维制备高导热、高强度的复合材料.通过SEM照片考察高密度聚乙烯/石墨/碳纤维复合体系的微观结构;研究石墨及碳纤维的加入是否可以形成导热通道以及随着石墨的添加量的提高,复合材料的导热性能及其力学性能的变化.结果表明:当石墨的质量分数为60%,碳纤维的质量分数为5%时,复合材料的导热系数达到7.938 W/(m·K),是纯HDPE的20倍.%High density polyethylene,graphite and carbon fiber were chosen to prepare a composite material with high thermal conductivity and high strength.Its microstructure was observed by SEM as well as whether it can form a thermal channel by using graphite and carbon fiber.The changes of the material's thermal conductivity and mechanical properties with the increasing of the addition of graphite were studied.When using 60w% graphite and 5 w% carbon fiber,the coefficient index of thermal conductivity reached at 7.938 W/(m · K) which was 20 times of the pure HDPE.

  10. STUEY ON THERMAL CONDUCTIVITY OF SALIX FIBER AND PP COMPOSITE%沙柳纤维/聚丙烯发泡复合材料导热性能研究

    Institute of Scientific and Technical Information of China (English)

    韩望; 张桂兰; 安珍; 富艳春

    2011-01-01

    An investigation has been performed on Thermal conductivity of Salix fiber and polypropylene (PP) Composite using combination of polymer foam technology and wood - based panel technology.Based on the variance analysis and maximum difference analysis :foaming agent, can significantly reduce the thermal conductivity of composite materials;the results also showed that:(1)hot process factors on Salix fiber/polypropylene foam thermal conductivity of composite materials are very significant; (2)Of the order: compound time, between the proportion of foaming agent, compound temperature, amount of blowing agent and coupling agent increases the amount of increase.%以聚合物发泡技术与人造板工艺技术相结合制备沙柳纤维/聚丙烯(PP)发泡复合材料,主要研究热压工艺对复合材料导热系数的影响.研究结果表明:添加发泡剂,可明显降低复合材料的导热系数;经方差极差分析得知:(1)热压工艺因子对沙柳纤维/聚丙烯发泡复合材料导热系数的影响均非常显著;(2)影响大小顺序:复合时间,发泡剂间比例,复合温度,发泡剂加量和偶联剂加量.

  11. 表面处理对碳纤维复合材料导电性的影响%Influence of Surface Treatments on Conductive Properties of Carbon Fiber/Epoxy Resin Composites

    Institute of Scientific and Technical Information of China (English)

    陈红燕; 黄华波

    2014-01-01

    In order to improve the stability of electrical properties of carbon fiber /epoxy resin composites .The resistance-temperature property of carbon fiber/epoxy resin composites was investigated using carbon fiber ( CF ) mat treated with titanate coupling agent as conductive fillers .The result showed that as the CF fraction increased , the stability of dectrical resistance of composites was enhanced under temperature variation .In addition of the electric resistivity of composities was remarkly enhanced and temperature-dependent fluctuation of resistance value was langely decreased after the surface treatment of CF .%为提高碳纤维/环氧树脂复合材料电性能的稳定性,采用钛酸酯偶联剂对碳纤维表面进行了处理,研究了以短切碳纤维毡为导电填料、环氧树脂为基体的导电复合材料的电阻-温度特性。结果表明:随碳纤维含量的增高,复合材料的电阻在温度变化下的稳定性增强;碳纤维经表面处理后,其复合材料的电阻率显著降低,且电阻值随温度的波动性也大幅下降。

  12. Performance experiments of carbon fiber-reinforced conductive SBS modified asphalt mixture%碳纤维导电SBS改性沥青混合料性能试验

    Institute of Scientific and Technical Information of China (English)

    查旭东; 蔡良; 曹艳霞

    2014-01-01

    In order to analyze pavement performances and ice-melting effects of conductive asphalt concrete,the chopped polyacrylonitrile-based carbon fibers were incorporated into SBS modified asphalt mixture AC-13C to prepare the carbon fiber-reinforced conductive modified asphalt mixtures.Five kinds of carbon fiber contents were selected respectively to conduct the laboratory experiments such as mix ratio design,pavement performances and simulated ice-melting etc.The results show,with the increase of carbon fiber content,the optimum asphalt-aggregate ratios of SBS modified asphalt mixture increase linearly;the dy-namic stability,the immersion residual Marshall stability and the freeze-thaw split strength ratios change in parabolic relationship;the low-temperature flexural-tensile strengths and the failure strains increase in"S"curve,but the stiffness moduli decrease in"Z"curve.It il-lustrates when the proper carbon fibers were incorporated into the SBS modified asphalt mixture,the pavement performances such as high-temperature anti-rutting,low-tempera-ture anti-cracking and moisture damage resistance etc can be improved because of the bridg-ing,reinforced and toughening effects of carbon fiber.However,the excessive carbon fibers can cause the decrease of enhancement effect because of poor dispersion and easy cluster. Simultaneously,when the carbon fiber contents are more than 0.3%,the carbon fibers in-side mixtures are lapped each other to form the good conductive network with the fine ice-melting results.On the whole,when the carbon fiber content is 0.4%,the pavement per-formances,the electrical conductivity and the ice-melting efficiency of carbon fiber-rein-forced SBS modified asphalt mixture are the best.%为了分析导电沥青混凝土的路用性能和融冰效果,将短切聚丙烯腈基碳纤维掺入 SBS改性沥青混合料 AC-13 C中,制备成碳纤维导电改性沥青混合料。选取5种碳纤维掺量分别进行了配合比设计、路用性能和模拟

  13. 预测纤维增强气凝胶复合材料热导率的研究进展∗%Predicting Thermal Conductivity of Fiber-reinforced Aerogel Composite Materials

    Institute of Scientific and Technical Information of China (English)

    杨建明; 吴会军; 王沫然

    2015-01-01

    SiO2气凝胶复合材料具有纳米尺度结构和极低热导率,作为隔热保温材料在航天航空、建筑和其他工业领域具有重要的科学和应用价值。根据纤维在气凝胶基体中的不同分布方式,概述了预测 SiO2气凝胶复合材料的气固耦合热导率的研究进展;基于纤维和气凝胶的消光系数的不同计算方法,概述了预测 SiO2气凝胶复合材料的辐射热导率的研究进展。并提出了纤维增强气凝胶复合材料体系存在的跨尺度、多物相、分级及相互耦合等仍需进一步解决的难题,结合最新发展的格子 Boltzmann 方法(LBM),指出了预测 SiO2气凝胶复合材料等效热导率的可能发展方向。%SiO2 aerogel composites with nano-scale structure and very low thermal conductivity have widely been used in aeronautics and astronautics,construction and other industries for thermal insulations.The research de-velopment in the conductive thermal conductivity of the SiO2 aerogel composites are reviewed according to the various distribution modes of reinforced fibers in aerogel matrix.Based on the calculation methods of the extinction coefficients of aerogels and fiber reinforcements,the advances in the radiative thermal conductivity of the SiO2 aerogel composites are demonstrated.The existing difficulties in predicting the effective thermal conductivity of the SiO2 aerogel compo-sites are generalized relevant to the cross scale,multiphase,classification and interconnection in the fiber-reinforced SiO2 aerogel composites.The perspective of the accurate prediction of the effective thermal conductivity of SiO2 aero-gel composites is also proposed involving a newly developed method - lattice Boltzmann method.

  14. Electrical Conductivity in Textiles

    Science.gov (United States)

    2006-01-01

    Copper is the most widely used electrical conductor. Like most metals, though, it has several drawbacks: it is heavy, expensive, and can break. Fibers that conduct electricity could be the solutions to these problems, and they are of great interest to NASA. Conductive fibers provide lightweight alternatives to heavy copper wiring in a variety of settings, including aerospace, where weight is always a chief concern. This is an area where NASA is always seeking improved materials. The fibers are also more cost-effective than metals. Expenditure is another area where NASA is always looking to make improvements. In the case of electronics that are confined to small spaces and subject to severe stress, copper is prone to breaking and losing connection over time. Flexible conductive fibers eliminate that problem. They are more supple and stronger than brittle copper and, thus, find good use in these and similar situations. While clearly a much-needed material, electrically conductive fibers are not readily available. The cost of new technology development, with all the pitfalls of troubleshooting production and the years of testing, and without the guarantee of an immediate market, is often too much of a financial hazard for companies to risk. NASA, however, saw the need for electrical fibers in its many projects and sought out a high-tech textile company that was already experimenting in this field, Syscom Technology, Inc., of Columbus, Ohio. Syscom was founded in 1993 to provide computer software engineering services and basic materials research in the areas of high-performance polymer fibers and films. In 1999, Syscom decided to focus its business and technical efforts on development of high-strength, high-performance, and electrically conductive polymer fibers. The company developed AmberStrand, an electrically conductive, low-weight, strong-yet-flexible hybrid metal-polymer YARN.

  15. Drop Weight Impact Studies of Woven Fibers Reinforced Modified Polyester Composites

    Directory of Open Access Journals (Sweden)

    Muhammed Tijani ISA

    2014-02-01

    Full Text Available Low velocity impact tests were conducted on modified unsaturated polyester reinforced with four different woven fabrics using hand-layup method to investigate the effect of fiber type and fiber combinations. The time-load curves were analysed and scanning electron microscopy was used to observe the surface of the impacted composite laminates. The results indicated that all the composites had ductility index (DI of above two for the test conducted at impact energy of 27J with the monolithic composite of Kevlar having the highest DI. The damage modes observed were mainly matrix cracks and fiber breakages. Hybridization of the fibers in the matrix was observed to minimize these damages.

  16. ZBLAN, Silica Fiber Comparison

    Science.gov (United States)

    1998-01-01

    This graph depicts the increased signal quality possible with optical fibers made from ZBLAN, a family of heavy-metal fluoride glasses (fluorine combined zirconium, barium, lanthanum, aluminum, and sodium) as compared to silica fibers. NASA is conducting research on pulling ZBLAN fibers in the low-g environment of space to prevent crystallization that limits ZBLAN's usefulness in optical fiber-based communications. In the graph, a line closer to the black theoretical maximum line is better. Photo credit: NASA/Marshall Space Flight Center

  17. Cell flow analysis with a two-photon fluorescence fiber probe

    Science.gov (United States)

    Chang, Yu-Chung; Ye, Jing Yong; Thomas, Thommey P.; Baker, James R., Jr.; Norris, Theodore B.

    2010-11-01

    We report the use of a sensitive double-clad fiber (DCF) probe for in situ cell flow velocity measurements and cell analysis by means of two-photon excited fluorescence correlation spectroscopy (FCS). We have demonstrated the feasibility to use this fiber probe for in vivo two-photon flow cytometry previously. However, because of the viscosity of blood and the non-uniform flow nature in vivo, it is problematic to use the detected cell numbers to estimate the sampled blood volume. To precisely calibrate the sampled blood volume, it is necessary to conduct real time flow velocity measurement. We propose to use FCS technique to measure the flow velocity. The ability to measure the flow velocities of labeled cells in whole blood has been demonstrated. Our two-photon fluorescence fiber probe has the ability to monitor multiple fluorescent biomarkers simultaneously. We demonstrate that we can distinguish differently labeled cells by their distinct features on the correlation curves. The ability to conduct in situ cell flow analysis using the fiber probe may be useful in disease diagnosis or further comprehension of the circulation system.

  18. Fiber diffraction without fibers.

    Science.gov (United States)

    Poon, H-C; Schwander, P; Uddin, M; Saldin, D K

    2013-06-28

    Postprocessing of diffraction patterns of completely randomly oriented helical particles, as measured, for example, in so-called "diffract-and-destroy" experiments with an x-ray free electron laser can yield "fiber diffraction" patterns expected of fibrous bundles of the particles. This will allow "single-axis alignment" to be performed computationally, thus obviating the need to do this by experimental means such as forming fibers and laser or flow alignment. The structure of such particles may then be found by either iterative phasing methods or standard methods of fiber diffraction.

  19. 原位聚合法制备聚苯胺/涤纶导电纤维%Preparation of polyaniline/polyester conductive fiber with in-situ polymerization

    Institute of Scientific and Technical Information of China (English)

    乔欣; 杜建功; 崔淑玲

    2011-01-01

    采用原位聚合法制备聚苯胺/涤纶复合导电纤维,探讨碱处理、氧化剂和掺杂酸用量、反应温度和反应时间等因素对纤维导电性能的影响.试验结果表明,通过控制反应条件,可使涤纶纤维有效吸附聚苯胺,制备出性能优良的导电纤维.其较佳工艺条件为:过硫酸铵浓度0.6 mol/L,对甲苯磺酸浓度1 moL/L,反应时间2 h,反应温度15~25℃.%Polyaniline/polyester composite conductive fiber is prepared with in-situ polymerization. Influences of alkali treatment, dosages of oxidant and doping acid, reaction temperature and time on conduaivity are discussed. The results show that conductive fiber with good property can be prepared by adsorbing polyaniline on polyester under controlled reaction conditions.The optimum process is carried out at 15~25℃ for 2 hours with ammonium persulfate 0.6 mol/L, and p-toluenesulfonic acid 1.0 mol/L.

  20. Damping Properties of Piezoelectric and Electrical Conductive of BaTiO3/VGCF/CPE Composites: Effect of Carbon Fiber

    Institute of Scientific and Technical Information of China (English)

    晏雄; 张慧萍; 住田雅夫

    2001-01-01

    A new damping composite of CPE/BaTiO3/VGCF has been developed on the basis of the piezo- effect and conductivity mechanism. The conductivity of composites varied with the VGCF content are tested and analyzed.The results indicate that the conductivity of composites grows up slowly as the VGCF content is in the range of 10%-20%. It is very useful for industrial application to control the conductivity of composites by adjusting the VGCF content. In addition, at the range of - 50 - 120°C,the dependence of loss factor on the VGCF content varied with the temperature are tested and analyzed by dynamic mechanical and dielectric behavior measurement of the composites, and expected results are obtained.

  1. PAD and PAH response patterns of group Ia- and Ib-fibers to cutaneous and descending inputs in the cat spinal cord.

    Science.gov (United States)

    Rudomin, P; Solodkin, M; Jiménez, I

    1986-10-01

    The characteristics of the primary afferent depolarization (PAD) of Ia- and Ib-fibers generated by segmental and descending inputs have been analyzed in the spinal cord of anesthetized cats. The PAD was inferred from the changes produced by conditioning inputs on the intraspinal stimulus current required to produce a constant antidromic firing of single group I afferent fibers from the gastrocnemius (GS) or posterior biceps and semitendinosus (PBSt) nerves. Group I GS and PBSt fibers ending in the intermediate nucleus could be classified in three different types according to their PAD patterns in response to stimulation of cutaneous nerves and of descending fibers. In one set of group I fibers stimulation of cutaneous nerves and of the ipsilateral brain stem reticular formation, or the contralateral red nucleus, produced no PAD, but was able to inhibit the PAD generated by stimulation of group I fibers from flexors (type A PAD pattern). PBSt nerve fibers with this PAD pattern had peripheral thresholds and conduction velocities between 1.01 and 1.56 times threshold and 76.3 to 118 m/s, respectively. A second set of group I fibers was found to be depolarized by cutaneous nerves as well as by stimulation of rubrospinal and reticulospinal fibers (type B PAD pattern). The peripheral thresholds and conduction velocities of PBSt afferent fibers with a type B PAD pattern were of 1.66-2.03 times threshold and 71-83 m/s, respectively. We found a third set of group I fibers that were also depolarized by reticulospinal and rubrospinal inputs, but not by cutaneous nerves that instead inhibited the PAD elicited by group I volleys in flexor nerves (type C PAD pattern). All PBSt afferent fibers with a type C PAD pattern, with the exception of two, had peripheral thresholds and velocities between 1.46 and 2.16 times threshold and between 72 and 89 m/s, respectively. Stimulation of the Deiter's nucleus was found to depolarize the intraspinal terminals of a small fraction of group I

  2. Technical Operations Support III (TOPS III). Delivery Order 0081: Novel Pitch Materials for High Thermal Conductivity Carbon Fibers, Foams and Composites - Phase 3

    Science.gov (United States)

    2011-06-01

    method [6]. An important addition to the technique is that during compression failure, high-speed video was captured using a Phantom V7.0 camera, the...However, the high speed cinematography has facilitated the capturing of the event [7]. Figure 3. A Schematic of a Mounted Specimen for...conductivity of 350 ±130 W/m*K as calculated from the thermal flash technique and 520 ±70 W/m*K as calculated from the electrical resistivity

  3. How to measure propagation velocity in cardiac tissue: a simulation study

    Directory of Open Access Journals (Sweden)

    Andre C. Linnenbank

    2014-07-01

    Full Text Available To estimate conduction velocities from activation times in myocardial tissue, the average vector method computes all the local activation directions and velocities from local activation times and estimates the fastest and slowest propagation speed from these local values. The single vector method uses areas of apparent uniform elliptical spread of activation and chooses a single vector for the estimated longitudinal velocity and one for the transversal. A simulation study was performed to estimate the influence of grid size, anisotropy, and vector angle bin size. The results indicate that the average vector method can best be used if the grid- or bin-size is large, although systematic errors occur. The single vector method performs better, but requires human intervention for the definition of fiber direction. The average vector method can be automated.

  4. Fiber biology

    Science.gov (United States)

    Cotton fiber cells arising from seed epidermis is the most important agricultural textile commodity in the world. To produce fully mature fibers, approximately two months of fiber developmental process are required. The timing of four distinctive fiber development stages consisting of initiation, ...

  5. High frequency stimulation of afferent fibers generates asynchronous firing in the downstream neurons in hippocampus through partial block of axonal conduction.

    Science.gov (United States)

    Feng, Zhouyan; Wang, Zhaoxiang; Guo, Zheshan; Zhou, Wenjie; Cai, Ziyan; Durand, Dominique M

    2017-04-15

    Deep brain stimulation (DBS) is effective for treating neurological disorders in clinic. However, the therapeutic mechanisms of high-frequency stimulation (HFS) of DBS have not yet been elucidated. Previous studies have suggested that HFS-induced changes in axon conduction could have important contributions to the DBS effects and desiderate further studies. To investigate the effects of prolonged HFS of afferent axons on the firing of downstream neurons, HFS trains of 100 and 200Hz were applied on the Schaffer collaterals of the hippocampal CA1 region in anaesthetized rats. Single unit activity of putative pyramidal cells and interneurons in the downstream region was analyzed during the late periods of prolonged HFS when the axonal conduction was blocked. The results show that the firing rates of both pyramidal cells and interneurons increased rather than decreased during the period of axon block. However, the firing rates were far smaller than the stimulation frequency of HFS. In addition, the firing pattern of pyramidal cells changed from typical bursts during baseline recordings into regular single spikes during HFS periods. Furthermore, the HFS produced asynchronous firing in the downstream neurons in contrast to the synchronous firing induced by single pulses. Presumably, the HFS-induced block of axonal conduction was not complete. During the period of partial block, individual axons could recover intermittently and independently, and drive the downstream neurons to fire in an asynchronous pattern. This axonal mechanism of HFS provides a novel explanation for how DBS could replace an original pattern of neuronal activity by a HFS-modulated asynchronous firing in the target region thereby generating the therapeutic effects of DBS.

  6. 外加电压对沥青碳纤维/ABS树脂复合材料导电性的影响%INFLUENCE OF EXTERNAL VOLTAGE ON THE CONDUCTIVITY OF COMPOSITES COMPOSED OF CARBON FIBERS AND ABS RESIN

    Institute of Scientific and Technical Information of China (English)

    梁晓怿; 凌立成; 吕春祥; 刘朗

    2001-01-01

    通用级沥青碳纤维与ABS树脂通过单螺杆挤出机共混后模压成型, 所制复合材料的电阻率随材料中纤维添加量的增多而迅速降低.当复合材料中纤维添加量较少时,材料的电流电压关系不满足欧姆定律所描述的线性关系,材料电阻随外电压的增大而减小.随着纤维含量的增加,材料电流电压关系的线性度逐渐增大.当纤维含量达到40 wt%时,材料电阻不随外电压的增大而变化,材料满足欧姆定律.经外加高电压处理后,材料电阻率发生永久性降低,其电流电压关系的线性度提高.隧道跃迁理论能够较好地解释上述现象.%Conductive ABS resin composites filled with general pitch-based carbon fibers were fabricated by hot-press moulding after raw materials were preblended through a single screw extruder. The composite resistivity decreases with fibers content going up. And the electrical current displays non-linear dependence on the external voltage acted on composites and the resistance of composites varies down with the raise of voltage, which implies that the composites don't meet Ohm's Law. When fibers fraction increases, the linearity between current and voltage goes up correspondingly. For the sample containing fillers of 40 wt%, its resistance remains constant and it satisfies Ohm's Law very well. It is interesting that the high voltage can result in the permanent reduction of composite resistance. And the voltage, which makes the permanent reduction of composites resistance, goes up with the increase of fillers loading. Moreover, the linearity of current and voltage rises after composites were treated by high voltage. All these phenomena can be explained by quantum tunneling model the results of this paper provide a new method for improving the conductivity and stability to varied voltage of composites.

  7. Carbon Fiber Reinforced Polymer with Shredded Fibers: Quasi-Isotropic Material Properties and Antenna Performance

    OpenAIRE

    Gerald Artner; Philipp K. Gentner; Johann Nicolics; Mecklenbräuker, Christoph F.

    2017-01-01

    A carbon fiber reinforced polymer (CFRP) laminate, with the top layer consisting of shredded fibers, is proposed and manufactured. The shredded fibers are aligned randomly on the surface to achieve a more isotropic conductivity, as is desired in antenna applications. Moreover, fiber shreds can be recycled from carbon fiber composites. Conductivity, permittivity, and permeability are obtained with the Nicolson-Ross-Weir method from material samples measured inside rectangular waveguides in the...

  8. Velocity anticipation in the optimal velocity model

    Institute of Scientific and Technical Information of China (English)

    DONG Li-yun; WENG Xu-dan; LI Qing-ding

    2009-01-01

    In this paper,the velocity anticipation in the optimal velocity model (OVM) is investigated.The driver adjusts the velocity of his vehicle by the desired headway,which depends on both instantaneous headway and relative velocity.The effect of relative velocity is measured by a sensitivity function.A specific form of the sensitivity function is supposed and the involved parameters are determined by the both numerical simulation and empirical data.It is shown that inclusion of velocity anticipation enhances the stability of traffic flow.Numerical simulations show a good agreement with empirical data.This model provides a better description of real traffic,including the acceleration process from standing states and the deceleration process approaching a stopped car.

  9. RESEARCH ON THE MOTION OF PARTICLES IN THE TURBULENT PIPE FLOW OF FIBER SUSPENSIONS

    Institute of Scientific and Technical Information of China (English)

    张卫峰; 林建忠

    2004-01-01

    The motion of fibers in turbulent pipe flow was simulated by 3-D integral method based on the slender body theory and simplified model of turbulence. The orientation distribution of fibers in the computational area for different Re numbers was computed. The results which were consistent with the experimental ones show that the fluctuation velocity of turbulence cause fibers to orient randomly. The orientation distributions become broader as the Re number increases. Then the fluctuation velocity and angular velocity of fibers were obtained. Both are affected by the fluctuation velocity of turbulence. The fluctuation velocity intensity of fiber is stronger at longitudinal than at lateral, while it was opposite for the fluctuation angular velocity intensity of fibers. Finally, the spatial distribution of fiber was given. It is obvious that the fiber dispersion is strenghened with the increase of Re numbers.

  10. Hierarchical Ni-Co layered double hydroxide nanosheets entrapped on conductive textile fibers: a cost-effective and flexible electrode for high-performance pseudocapacitors

    Science.gov (United States)

    Nagaraju, Goli; Raju, G. Seeta Rama; Ko, Yeong Hwan; Yu, Jae Su

    2015-12-01

    Hierarchical three-dimensional (3D) porous nanonetworks of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets (NSs) are grown and decorated on flexible conductive textile substrate (CTs) via a simple two-electrode system based electrochemical deposition (ED) method. By applying a proper external cathodic voltage of -1.2 V for 15 min, the Ni-Co LDH NSs are densely deposited over the entire surface of the CTs with good adhesion. The flexible Ni-Co LDH NSs on CTs (Ni-Co LDH NSs/CTs) architecture with high porosity facilitates enhanced electrochemical performance in 1 M KOH electrolyte solution. The effect of growth concentration and external cathodic voltage on the electrochemical properties of Ni-Co LDH NSs/CTs is also investigated. The Ni10Co5 LDH NSs/CTs electrode exhibits a high specific capacitance of 2105 F g-1 at a current density of 2 A g-1 as well as an excellent cyclic stability as a pseudocapacitive electrode due to the advantageous properties of 3D interconnected porous frameworks of Ni10Co5 LDH NSs/CTs. This facile fabrication of bimetallic hydroxide nanostructures on CTs can provide a promising electrode for low-cost energy storage device applications.Hierarchical three-dimensional (3D) porous nanonetworks of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets (NSs) are grown and decorated on flexible conductive textile substrate (CTs) via a simple two-electrode system based electrochemical deposition (ED) method. By applying a proper external cathodic voltage of -1.2 V for 15 min, the Ni-Co LDH NSs are densely deposited over the entire surface of the CTs with good adhesion. The flexible Ni-Co LDH NSs on CTs (Ni-Co LDH NSs/CTs) architecture with high porosity facilitates enhanced electrochemical performance in 1 M KOH electrolyte solution. The effect of growth concentration and external cathodic voltage on the electrochemical properties of Ni-Co LDH NSs/CTs is also investigated. The Ni10Co5 LDH NSs/CTs electrode exhibits a high

  11. ZBLAN Fiber Apparatus Tested

    Science.gov (United States)

    1998-01-01

    Dr. Dernis Tucker of NASA's Marshall Space Flight Center examines a miniature furnace to be used in studying the crystallization of ZBLAN optical fibers under low-gravity conditions aboard the NASA KC-135 low-g aircraft. NASA is conducting research on pulling ZBLAN fibers in the low-g environment of space to prevent crystallization that limits ZBLAN's usefulness in optical fiber-based communications. ZBLAN is a heavy-metal fluoride glass that shows exceptional promise for high-throughput communications with infrared lasers. Photo credit: NASA/Marshall Space Flight Center

  12. Comparisons among Different Reference Values of Nerve Conduction Velocity in Forensic Appraisal%法医学鉴定中神经传导检测不同参考值的比较

    Institute of Scientific and Technical Information of China (English)

    高东; 田东; 夏晴; 朱广友; 范利华

    2012-01-01

    Objective To provide the evidences for the choice of normal reference value of nerve conduction velocity (NCV) in clinical forensic appraisal. Methods One hundred and fourteen cases with normal peripheral nerve and 155 cases with injured peripheral nerve were collected. The NCV of homonymous nerves in two limbs were detected. In the normal cases, the NCV of the left limbs were used as the normal reference values. The NCV of the right limbs were compared with that of left limbs, the commendatory normal reference values from Beijing Xiehe Hospital and Shanghai Huashan Hospital. In the injured cases, the results of NCV in injuried limbs were compared with the results of healthy limbs and the reference values from Beijing Xiehe Hospital and Shanghai Huashan Hospital. Results In the normal group, there was no statistical difference between the left and right limbs in NCV results of homonymous nerve (P>0.05). The false positive rates (FPR) were 0, 11.4% and 5.2% for three choices normal reference respectively. The false negative rates (FNR) were 0, 9.7% and 12.3% for three choices normal reference in injuried group. The false negative cases were all slight nerve injury. Conclusion The reference value of self-control method could decrease the FPR of normal cases and FNR of injured cases. In clinical forensic appraisal of peripheral nerve, the nerve condition study results from healthy homonymous nerve should be regarded as the reference value at first, supplemented by reference values from clinical labs.%目的 为法医临床学鉴定实践中周围神经传导检测正常参考值的选择提供依据.方法 选取周围神经正常者114例和周围神经损伤者155例,对双侧肢体的同名神经进行神经传导检测.在正常组中,以左侧肢体的检测结果作为正常参考值,将右侧肢体的检测结果分别与左侧、北京协和医院和上海华山医院推荐的正常参考值进行比较并进行统计.在损伤组中,将伤侧肢体的检测

  13. Drop impact on a flexible fiber

    CERN Document Server

    Dressaire, Emilie; Boulogne, François; Stone, Howard A

    2015-01-01

    When droplets impact fibrous media, the liquid can be captured by the fibers or contact then break away. Previous studies have shown that the efficiency of drop capture by a rigid fiber depends on the impact velocity and defined a threshold velocity below which the drop is captured. However, it is necessary to consider the coupling of elastic and capillary effects to achieve a greater understanding of the capture process for soft substrates. Here, we study experimentally the dynamics of a single drop impacting on a thin flexible fiber. Our results demonstrate that the threshold capture velocity depends on the flexibility of fibers in a non-monotonic way. We conclude that tuning the mechanical properties of fibers can optimize the efficiency of droplet capture.

  14. Soft capacitor fibers for electronic textiles

    Science.gov (United States)

    Gu, Jian Feng; Gorgutsa, Stephan; Skorobogatiy, Maksim

    2010-09-01

    A highly flexible, conductive polymer-based fiber with high electric capacitance is reported. The fiber is fabricated using fiber drawing method, where a multimaterial macroscopic preform is drawn into a submillimeter capacitor microstructured fiber. A typical measured capacitance per unit length of our fibers is 60-100 nF/m which is about 3 orders magnitude higher than that of a coaxial cable of a comparable diameter. The fiber has a transverse resistivity of 5 kΩ m. Softness, lightweight, absence of liquid electrolyte, and ease of scalability to large production volumes make the fibers interesting for various smart textile applications.

  15. Dietary Fiber

    Science.gov (United States)

    Fiber is a substance in plants. Dietary fiber is the kind you eat. It's a type of carbohydrate. You may also see it listed on a food label as soluble ... types have important health benefits. Good sources of dietary fiber include Whole grains Nuts and seeds Fruit and ...

  16. Fiber Amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten

    2017-01-01

    The chapter provides a discussion of optical fiber amplifiers and through three sections provides a detailed treatment of three types of optical fiber amplifiers, erbium doped fiber amplifiers (EDFA), Raman amplifiers, and parametric amplifiers. Each section comprises the fundamentals including t...

  17. [Classification and the composition of food fibers].

    Science.gov (United States)

    Bezhanidze, I Z; Alasaniia, N Sh; Kontselidze, L A; Kharazi, N A; Bezhanidze, N V

    2009-06-01

    Fiber promotes the contractions that keep food moving through the intestine. Also, high-fiber foods expand the inside walls of the colon and eases the passage of waste. The food and fiber research was conducted. In the article, the classification and the composition of food fibers are presented. Multifunctional properties of food fiber in the process of digestion are discussed. The physiological value of food fibers for the human organism is stressed. Diets high in fiber during the entire life are recommended. If a person can't consume enough fiber in diet alone, certain stool softening and bulking agents are recommended. They can be very useful in preventing and treating digestive tract disorders. The analysis of high fiber food sources and world production and consumption of food fiber is also presented.

  18. Water Fibers

    CERN Document Server

    Douvidzon, Mark L; Martin, Leopoldo L; Carmon, Tal

    2016-01-01

    Fibers constitute the backbone of modern communication and are used in laser surgeries; fibers also genarate coherent X-ray, guided-sound and supercontinuum. In contrast, fibers for capillary oscillations, which are unique to liquids, were rarely considered in optofluidics. Here we fabricate fibers by water bridging an optical tapered-coupler to a microlensed coupler. Our water fibers are held in air and their length can be longer than a millimeter. These hybrid fibers co-confine two important oscillations in nature: capillary- and electromagnetic-. We optically record vibrations in the water fiber, including an audio-rate fundamental and its 3 overtones in a harmonic series, that one can hear in soundtracks attached. Transforming Micro-Electro-Mechanical-Systems [MEMS] to Micro-Electro-Capillary-Systems [MECS], boosts the device softness by a million to accordingly improve its response to minute forces. Furthermore, MECS are compatible with water, which is a most important liquid in our world.

  19. Test and Numerical Analysis for Penetration Residual Velocity of Bullet Considering Failure Strain Uncertainty of Composite Plates

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Myungseok; Lee, Minhyung [Sejong Univ., Sejong (Korea, Republic of)

    2016-03-15

    The ballistic performance data of composite materials is distributed due to material inhomogeneity. In this paper, the uncertainty in residual velocity is obtained experimentally, and a method of predicting it is established numerically for the high-speed impact of a bullet into laminated composites. First, the failure strain distribution was obtained by conducting a tensile test using 10 specimens. Next, a ballistic impact test was carried out for the impact of a fragment-simulating projectile (FSP) bullet with 4ply ([0/90]s) and 8ply ([0/90/0/90]s) glass fiber reinforced plastic (GFRP) plates. Eighteen shots were made at the same impact velocity and the residual velocities were obtained. Finally, simulations were conducted to predict the residual velocities by using the failure strain distributions that were obtained from the tensile test. For this simulation, two impact velocities were chosen at 411.7m/s (4ply) and 592.5m/s (8ply). The simulation results show that the predicted residual velocities are in close agreement with test results. Additionally, the modeling of a composite plate with layered solid elements requires less calculation time than modeling with solid elements.

  20. ZBLAN Fiber Comparison

    Science.gov (United States)

    1998-01-01

    Sections of ZBLAN fibers pulled in a conventional 1-g process (left) and in experiments aboard NASA's KC-135 low-gravity aircraft. The rough surface of the 1-g fiber indicates surface defects that would scatter an optical signal and greatly degrade its quality. ZBLAN is part of the family of heavy-metal fluoride glasses (fluorine combined zirconium, barium, lanthanum, aluminum, and sodium). NASA is conducting research on pulling ZBLAN fibers in the low-g environment of space to prevent crystallization that limits ZBLAN's usefulness in optical fiber-based communications. ZBLAN is a heavy-metal fluoride glass that shows exceptional promise for high-throughput communications with infrared lasers. Photo credit: NASA/Marshall Space Flight Center

  1. High-velocity clouds

    NARCIS (Netherlands)

    Wakker, BP; vanWoerden, H

    1997-01-01

    High-velocity clouds (HVCs) consist of neutral hydrogen (HI) at velocities incompatible with a simple model of differential galactic rotation; in practice one uses \\v(LSR)\\ greater than or equal to 90 km/s to define HVCs. This review describes the main features of the sky and velocity distributions,

  2. Transverse Spectral Velocity Estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    A transverse oscillation (TO)-based method for calculating the velocity spectrum for fully transverse flow is described. Current methods yield the mean velocity at one position, whereas the new method reveals the transverse velocity spectrum as a function of time at one spatial location. A convex...

  3. All-Fiber Configuration Laser Self-Mixing Doppler Velocimeter Based on Distributed Feedback Fiber Laser.

    Science.gov (United States)

    Wu, Shuang; Wang, Dehui; Xiang, Rong; Zhou, Junfeng; Ma, Yangcheng; Gui, Huaqiao; Liu, Jianguo; Wang, Huanqin; Lu, Liang; Yu, Benli

    2016-07-27

    In this paper, a novel velocimeter based on laser self-mixing Doppler technology has been developed for speed measurement. The laser employed in our experiment is a distributed feedback (DFB) fiber laser, which is an all-fiber structure using only one Fiber Bragg Grating to realize optical feedback and wavelength selection. Self-mixing interference for optical velocity sensing is experimentally investigated in this novel system, and the experimental results show that the Doppler frequency is linearly proportional to the velocity of a moving target, which agrees with the theoretical analysis commendably. In our experimental system, the velocity measurement can be achieved in the range of 3.58 mm/s-2216 mm/s with a relative error under one percent, demonstrating that our novel all-fiber configuration velocimeter can implement wide-range velocity measurements with high accuracy.

  4. Preparation and characterization of large diameter pitch based carbon fiber/ABS resin composites with high thermal conductivities%大直径沥青基炭纤维/ABS树脂高导热复合材料的制备与表征

    Institute of Scientific and Technical Information of China (English)

    易静; 袁观明; 李轩科; 杜鸿达; 董志军; 李保六; 林剑峰

    2015-01-01

    将大直径中间相沥青基石墨化纤维定向排列后与ABS(丙烯腈_苯乙烯_丁二烯共聚物)树脂通过热压成型,制备出单向炭纤维ABS树脂基复合材料。借助X射线衍射、扫描电子显微镜和偏光显微镜等手段对炭纤维及其树脂基复合材料的晶体结构、形貌和光学织构进行表征,并研究纤维石墨化温度及体积分数对其复合材料导热性能的影响。结果表明,复合材料沿炭纤维轴向和径向显示出差异;复合材料沿纤维轴向的室温热扩散系数随纤维石墨化温度和体积分数的增加而增大。%Parallel, stretched and evenly arranged mesophase pitch based graphitized carbon fibers with diameters of 50_53 μm were coated with different amounts of acrylonitrile butadiene styrene ( ABS) resin, and hot_pressed to produce carbon fiber/ABS resin composites. The morphology, optical texture and crystal structure of the carbon fibers and their composites were characterized by scanning electron microscopy, polarized light microscopy and X_ray diffraction. The influence of the graphitization temperature and fiber content on the thermal conductivity of the composites was investigated. The thermal diffusivity and thermal conductivity of the composites along both fiber axial and radial directions showed an obvious difference, owing to the high orientation of the graphite crystals along the axial direction of the carbon fibers. The thermal diffusivity of the composites along the carbon fiber axial direction increased both with the graphitization temperature and fiber content. The composite with 54 vol.% carbon fibers graphitized at 2 900 ℃ showed the highest thermal conductivity.

  5. Effect of fiber material on ozone removal and carbonyl production from carpets

    Science.gov (United States)

    Abbass, Omed A.; Sailor, David J.; Gall, Elliott T.

    2017-01-01

    Indoor air quality is affected by indoor materials such as carpets that may act as sources and/or sinks of gas-phase air pollutants. Heterogeneous reactions of ozone with carpets may result in potentially harmful products. In this study, indoor residential carpets of varying fiber types were tested to evaluate their ability to remove ozone, and to assess their role in the production of carbonyls when exposed to elevated levels of ozone. Tests were conducted with six types of new unused carpets. Two sets of experiments were conducted, the first measured ozone removal and ozone deposition velocities, and the second measured primary carbonyl production and secondary production as a result of exposure to ozone. The tests were conducted using glass chambers with volume of 52 L each. Air exchange rates for all tests were 3 h-1. The ozone removal tests show that, for the conditions tested, the polyester carpet sample had the lowest ozone removal (40%), while wool carpet had the greatest ozone removal (65%). Most carpet samples showed higher secondary than primary carbonyl emissions, with carpets containing polypropylene fibers being a notable exception. Carpets with polyester fibers had both the highest primary and secondary emissions of formaldehyde among all samples tested. While it is difficult to make blanket conclusions about the relative air quality merits of various carpet fiber options, it is clear that ozone removal percentages and emissions of volatile organic compounds can vary drastically as a function of fiber type.

  6. Hollow fiber adsorbents for CO2 capture: Kinetic sorption performance

    KAUST Repository

    Lively, Ryan P.

    2011-07-01

    We describe a CO 2 capture platform based on hollow polymeric fibers with sorbent particles embedded in the porous fiber wall for post-combustion CO 2 capture. These fibers are intended for use in a rapid temperature swing adsorption (RTSA) process. The RTSA system utilizes the hollow fiber morphology by flowing cooling water on the bore-side of the fibers during sorption to prevent temperature rise associated with the sorption enthalpy. Steam or hot water is flowed through the bores during desorption to desorb CO 2 rapidly. To minimize material transfer between the bore and the fiber wall, a dense Neoprene ® lumen layer is cast on the bore-side of the fiber wall. In this paper, the key sorption step and associated kinetic resistances for the uncooled fibers are examined and evaluated for this portion of the RTSA process. Chopped fibers in a packed bed, as well as fibers assembled into a parallel flow module, have been tested in a simulated flue gas stream. Kinetic limitations in the hollow fiber modules are largely overcome by increasing the superficial gas velocity and the fiber packing in the module-indicating that film diffusion is the controlling mass transfer limitation in the fiber system. The un-cooled fiber modules lose apparent capacity as superficial velocities are increased, likely indicating non-isothermal operation, whereas the actively-cooled fibers in the packed bed maintain apparent capacity at all flowrates studied. © 2011 Elsevier B.V.

  7. Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

    Science.gov (United States)

    Tan, Seng; Zhou, Jian-guo

    2013-01-01

    Pitch-based nanocomposite carbon fibers were prepared with various percentages of carbon nanofibers (CNFs), and the fibers were used for manufacturing composite structures. Experimental results show that these nanocomposite carbon fibers exhibit improved structural and electrical conductivity properties as compared to unreinforced carbon fibers. Composite panels fabricated from these nanocomposite carbon fibers and an epoxy system also show the same properties transformed from the fibers. Single-fiber testing per ASTM C1557 standard indicates that the nanocomposite carbon fiber has a tensile modulus of 110% higher, and a tensile strength 17.7% times higher, than the conventional carbon fiber manufactured from pitch. Also, the electrical resistance of the carbon fiber carbonized at 900 C was reduced from 4.8 to 2.2 ohm/cm. The manufacturing of the nanocomposite carbon fiber was based on an extrusion, non-solvent process. The precursor fibers were then carbonized and graphitized. The resultant fibers are continuous.

  8. Numerical approach of the injection molding process of fiber-reinforced composite with considering fiber orientation

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Thi, T. B., E-mail: thanhbinh.skku@gmail.com, E-mail: yokoyama@kit.ac.jp; Yokoyama, A., E-mail: thanhbinh.skku@gmail.com, E-mail: yokoyama@kit.ac.jp [Department of Advanced Fibro-Science, Kyoto Institute of Technology (Japan); Ota, K., E-mail: kei-ota@toyobo.jp, E-mail: katsuhiro-kodama@toyobo.jp, E-mail: katsuhisa-yamashita@toyobo.jp, E-mail: yumiko-isogai@toyobo.jp, E-mail: kenji-furuichi@toyobo.jp, E-mail: chisato-nonomura@toyobo.jp; Kodama, K., E-mail: kei-ota@toyobo.jp, E-mail: katsuhiro-kodama@toyobo.jp, E-mail: katsuhisa-yamashita@toyobo.jp, E-mail: yumiko-isogai@toyobo.jp, E-mail: kenji-furuichi@toyobo.jp, E-mail: chisato-nonomura@toyobo.jp; Yamashita, K., E-mail: kei-ota@toyobo.jp, E-mail: katsuhiro-kodama@toyobo.jp, E-mail: katsuhisa-yamashita@toyobo.jp, E-mail: yumiko-isogai@toyobo.jp, E-mail: kenji-furuichi@toyobo.jp, E-mail: chisato-nonomura@toyobo.jp; Isogai, Y., E-mail: kei-ota@toyobo.jp, E-mail: katsuhiro-kodama@toyobo.jp, E-mail: katsuhisa-yamashita@toyobo.jp, E-mail: yumiko-isogai@toyobo.jp, E-mail: kenji-furuichi@toyobo.jp, E-mail: chisato-nonomura@toyobo.jp; Furuichi, K., E-mail: kei-ota@toyobo.jp, E-mail: katsuhiro-kodama@toyobo.jp, E-mail: katsuhisa-yamashita@toyobo.jp, E-mail: yumiko-isogai@toyobo.jp, E-mail: kenji-furuichi@toyobo.jp, E-mail: chisato-nonomura@toyobo.jp; Nonomura, C., E-mail: kei-ota@toyobo.jp, E-mail: katsuhiro-kodama@toyobo.jp, E-mail: katsuhisa-yamashita@toyobo.jp, E-mail: yumiko-isogai@toyobo.jp, E-mail: kenji-furuichi@toyobo.jp, E-mail: chisato-nonomura@toyobo.jp [Toyobo Co., LTD. Research Center (Japan)

    2014-05-15

    One of the most important challenges in the injection molding process of the short-glass fiber/thermoplastic composite parts is being able to predict the fiber orientation, since it controls the mechanical and the physical properties of the final parts. Folgar and Tucker included into the Jeffery equation a diffusive type of term, which introduces a phenomenological coefficient for modeling the randomizing effect of the mechanical interactions between the fibers, to predict the fiber orientation in concentrated suspensions. Their experiments indicated that this coefficient depends on the fiber volume fraction and aspect ratio. However, a definition of the fiber interaction coefficient, which is very necessary in the fiber orientation simulations, hasn't still been proven yet. Consequently, this study proposed a developed fiber interaction model that has been introduced a fiber dynamics simulation in order to obtain a global fiber interaction coefficient. This supposed that the coefficient is a sum function of the fiber concentration, aspect ratio, and angular velocity. The proposed model was incorporated into a computer aided engineering simulation package C-Mold. Short-glass fiber/polyamide-6 composites were produced in the injection molding with the fiber weight concentration of 30 wt.%, 50 wt.%, and 70 wt.%. The physical properties of these composites were examined, and their fiber orientation distributions were measured by micro-computed-tomography equipment μ-CT. The simulation results showed a good agreement with experiment results.

  9. Carbon nanotube fiber spun from wetted ribbon

    Science.gov (United States)

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  10. Femtosecond Fiber Lasers

    Science.gov (United States)

    Bock, Katherine J.

    -order dispersion contribution from the diffraction gratings inside the laser cavity was studied, as it was also considered to be an energy-limiting factor. No significant effect was found as a result of third-order dispersion; however, a region of operation was observed where two different pulse regimes were found at the same values of net cavity group velocity dispersion. Results verify the main idea and indicate that a long length of low-doped gain fiber is preferable to a shorter, more highly doped one. The low-doped fiber in an otherwise equivalent cavity allows the nonlinear phase shift to grow at a slower rate, which results in the pulse achieving a higher peak power before reaching the nonlinear phase shift threshold at which optical wave breaking occurs. For a range of net cavity group velocity dispersion values, the final result is that the low doped fiber generates pulses of approximately twice the value of energy of the highly-doped gain fiber. Two techniques of mode-locking cavities were investigated to achieve this result. The first cavity used NPE mode-locking which masked the results, and the second used a SESAM for mode-locking which gave clear results supporting the hypothesis.

  11. Palm Date Fibers: Analysis and Enzymatic Hydrolysis

    Directory of Open Access Journals (Sweden)

    Mohammad J. Taherzadeh

    2010-11-01

    Full Text Available Waste palm dates were subjected to analysis for composition and enzymatic hydrolysis of their flesh fibers. The fruit contained 32% glucose and 30% fructose, while the water-insoluble fibers of its flesh consisted of 49.9% lignin and 20.9% polysaccharides. Water-insoluble fibers were settled to 55% of its initial volume in 12 h. The presence of skin and flesh colloidal fibers results in high viscosity and clogging problems during industrial processes. The settling velocity of the fibers was improved by enzymatic hydrolysis. Hydrolysis resulted in 84.3% conversion of the cellulosic part of the fibers as well as reducing the settling time to 10 minutes and the final settled volume to 4% of the initial volume. It implies easier separation of the fibers and facilitates fermentation processes in the corresponding industries. Two kinds of high- and low-lignin fibers were identified from the water-insoluble fibers. The high-lignin fibers (75% lignin settled easily, while the low-lignin fibers (41.4% lignin formed a slurry suspension which settled very slowly. The hydrophilicity of these low-lignin fibers is the major challenge of the industrial processes.

  12. Dynamic Properties of Fiber Reinforced Cement Mortar

    Institute of Scientific and Technical Information of China (English)

    唐志平; 徐松林; 胡晓军; 廖香丽; 蔡建

    2004-01-01

    Based on the shear wave tracing(SWT) technique proposed by Tang Z P, particle velocity gauge and the dual internal measurement for pressure and shear waves (IMPS) system are applied to investigate the responses of fiber reinforced cement subjected to impact loading. Series of experiments are conducted. The results show that there exist four critical points, A, B, C, D, in p-V Hugoniot curves. They correspond to the Hugoniot elastic limit (HEL) of the material, the critical point for shear strength limit and transition from damage state to failure state, void collapse, and solid compression, respectively. The critical point B is difficult to be aware of and never reported. However, it can be clearly disclosed with SWT method. Based on the analyses of shear strength, it can be concluded that the transversal wave, especially the unloading transversal wave, is especially important for the dynamic damage investigation of brittle materials.

  13. Capillary electrochromatography using fibers as stationary phases.

    Science.gov (United States)

    Jinno, K; Watanabe, H; Saito, Y; Takeichi, T

    2001-10-01

    Fiber-packed capillary columns have been evaluated in chromatographic performance in capillary electrochromatography (CEC). The change of electroosmotic flow (EOF) velocity and selectivity using different kinds of fiber materials was examined. Although the EOF velocity among the different fiber packed columns was almost the same, retention of parabens was larger on the Kevlar-packed column than on the Zylon-packed one, and was larger on the as-span-type fiber-packed column than on the high-modulus-type packed one. Using 200 microm ID x 5 cm Kevlar packed column combined with a 100 microm ID x 20 cm precolumn capillary and a 530 microm ID x 45 cm postcolumn capillary, the separation of three parabens within 30 s was achieved. Other compounds were also separated in a few minutes by the fiber-packed CEC method.

  14. Velocity selective optical pumping

    OpenAIRE

    Aminoff, C. G.; Pinard, M.

    1982-01-01

    We consider optical pumping with a quasi monochromatic tunable light beam, in the low intensity limit where a rate equation regime is obtained The velocity selective optical pumping (V.S.O.P.) introduces a correlation between atomic velocity and internal variables in the ground (or metastable) state. The aim of this article is to evaluate these atomic observables (orientation, alignment, population) as a function of velocity, using a phenomenological description of the relaxation effect of co...

  15. Convection and radiation effects in hollow, compound optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J.I. [Room I-320-D, ETS Ingenieros Industriales, Universidad de Malaga, Plaza El Ejido, s/n, 29013 Malaga (Spain)

    2005-09-01

    A coupled model for the study of hollow, compound optical fiber drawing processes that accounts for the heat transfer in the preform and fiber and for the motion of the gases surrounding the preform and fiber by means of two-dimensional equations, employs a net radiative model for the radiative heat exchanges amongst the preform, fiber, irises and furnace walls, and uses asymptotic one-dimensional equations for the geometry, axial velocity component and temperature along the fiber for small Biot numbers is presented. It is shown that the coupled model predicts that radiative heat exchanges are about three times larger than forced convection effects, and free convection is not important. It is also shown that the fiber's geometry, axial velocity and temperature predicted by the coupled model are in remarkable good agreement with those obtained with only the one-dimensional model for hollow, compound fibers using a properly chosen constant Biot number. The results of the one-dimensional model for hollow, compound fibers show that, as the heat transfer losses from the fiber increase, the fiber's dynamic viscosity increases, the fiber exhibits a strong necking phenomenon and the fiber's axial velocity increases rapidly from its value at the die's exit to a constant value downstream and then remains constant. For the boundary conditions considered in this paper, it is shown that the activation energies of the viscosity laws for the inner and outer materials of the hollow, compound fiber do not have very strong effects on the fiber's geometry, axial velocity component and temperature, whereas the fiber's solidification point moves towards the die as the thermal Peclet number is decreased. It is also shown that the pre-exponential factor and activation energy of the dynamic viscosity law do not play a key role in determining the fiber's geometry and temperature for the conditions analyzed in this paper. (authors)

  16. Mechanical Properties of Palm Fiber Mattress

    Science.gov (United States)

    Li, Yu-Qian; Wu, Jia-Yu; Gu, Hao-Wei; Chen, Zong-Yong; Shi, Xiao-Bing; Liao, Ting-Mao; An, Cheng; Yuan, Hong; Liu, Ren-Huai

    2016-05-01

    Palm fiber mattress is increasingly accepted by many families. This study aims at evaluating the mechanical properties of palm fiber mattress. Two experiments were conduct to investigate the Young's modulus of palm fiber mattress in three directions. In addition, finite element models were established to characterize palm fiber mattress under uniform distributed pressure. Finally, results from finite element analysis are presented to illustrate that the thick mattress will stick with human body curve perfectly, which can support vertebral column effectively.

  17. Diode Pumped Fiber Laser.

    Science.gov (United States)

    1984-12-01

    FIBER LASERS I. Nd:YAG FIBER LASER FABRICATION .............. 5 A. FIBER GROWTH .......................... 5 B. FIBER PROCESSING 7...1.32 pm FIBER LASERS I. Nd:YAG FIBER LASER FABRICATION A. FIBER GROWTH The single crystal fibers used in this work were grown at Stanford University

  18. Numerical analysis of natural convection in thermoelectrically conducting fluids in a cubic cavity under a constant magnetic field. 2nd Report. Effect of direction of magnetic field on thermal and velocity field on thermal and velocity fields; Jibaka ni okeru denji netsuryutai no rippotai cavity nai shizen tairyu kaiseki. 2. Inka jiba hoko no netsuryudoba eno eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Nakai, T.; Tanahashi, T. [Keio University, Tokyo (Japan). Faculty of Science and Technology

    1996-01-25

    In a previous paper, we investigated the natural convection in thermoelectrically conducting fluids in a cubic cavity under a magnetic field applied in the gravitational direction, and complicated fluid phenomena were clarified. Particularly in the case of mercury (Pr=0.025, Gr=3.75{times}10{sup 7}), the numerical results agreed well with the observed experimental results obtained using a thermosensitive liquid crystal sheet. In the present paper, we aim to explain the fundamental behavior of thermoelectrically conducting fluids, and numerically determine the natural convection by considering a different direction for the applied magnetic field. The direction of the applied magnetic field is chosen as either the +x, -y or +z direction (see Fig. 1). The convective inhibitory effect of the Lorentz force increases in the order of the +x, -y and +z-directions. 11 refs., 7 figs., 2 tabs.

  19. Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Weimin Song

    2016-08-01

    Full Text Available Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF and carbon fiber (CF was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC, carbon fiber reinforced concrete (CFRC and hybrid fiber reinforced concrete (HFRC were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored.

  20. Influence of Acupuncture-moxibustion on the Peroneal Nerve Conduction Velocity in Type 2 Diabetic Peripheral Neuropathy:A Meta-analysis%针灸治疗2型糖尿病周围神经病变对腓神经神经传导速度影响的Meta分析

    Institute of Scientific and Technical Information of China (English)

    刘吉琴; 柯宗萍; 谢丹丹; 柯行梅; 李雪锋

    2016-01-01

    目的:系统评价针灸治疗2型糖尿病周围神经病变(DPN)对腓神经神经传导速度的影响,为针灸治疗DPN提供临床参考。方法通过检索中国生物力学文献数据库(CBM)、中国期刊全文数据库(CNKI)、维普期刊数据库(VIP)、万方数据库、PubMed、Springer、Medline数据库,收集2000年1月至2014年1月关于针灸治疗2型DPN的随机对照试验(RCT),提取腓神经传导速度相关资料并进行方法学质量评价,采用RevMan 5.1软件进行Meta分析。结果共纳入10个随机对照试验,合计685例患者,其中治疗组355例,对照组330例。Meta分析结果显示,针灸治疗2型DPN在提高腓神经运动神经传导速度(MNCV)和感觉神经传导速度(SNCV)方面可能优于对照组,差异均有统计学意义[MD=3.55,95%CI(0.79,6.31);MD=4.10,95%CI (0.22,7.99)]。结论针灸治疗2型DPN可以改善腓神经传导速度,值得临床应用。但由于本系统评价纳入研究较少,样本量小,且质量不高,存在偏倚的高度可能性,因此上述结论尚需要高质量、大样本、多中心的随机对照试验加以证实。%Objective To systematically evaluate the influence of acupuncture-moxibustion on the peroneal nerve conduction velocity in type 2 diabetic peripheral neuropathy (DPN), and to provide clinical references for acupuncture-moxibustion treatment for DPN.Method By searching the CBM, CNKI, VIP, Wanfang, Pubmed, Springer and Medline databases, randomized controlled trials (RCT) of acupuncture-moxibustion for the type 2 DPN published from January 2000 to January 2014 were retrieved and the relevant data of the peroneal nerve conduction velocity were collected for methodological evaluation. RevMan 5.1 software was adopted to conduct the meta-analysis.Result Totally 10 RCTs were recruited with 685 cases involved, including 355 cases in the treatment group and 330 cases in the control group. The meta-analysis results indicated that acupuncture-moxibustion can

  1. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

  2. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

  3. Two Fiber Optical Fiber Thermometry

    Science.gov (United States)

    Jones, Mathew R.; Farmer, Jeffery T.; Breeding, Shawn P.

    2000-01-01

    An optical fiber thermometer consists of an optical fiber whose sensing tip is given a metallic coating. The sensing tip of the fiber is essentially an isothermal cavity, so the emission from this cavity will be approximately equal to the emission from a blackbody. Temperature readings are obtained by measuring the spectral radiative heat flux at the end of the fiber at two wavelengths. The ratio of these measurements and Planck's Law are used to infer the temperature at the sensing tip. Optical fiber thermometers have high accuracy, excellent long-term stability and are immune to electromagnetic interference. In addition, they can be operated for extended periods without requiring re-calibration. For these reasons. it is desirable to use optical fiber thermometers in environments such as the International Space Station. However, it has recently been shown that temperature readings are corrupted by emission from the fiber when extended portions of the probe are exposed to elevated temperatures. This paper will describe several ways in which the reading from a second fiber can be used to correct the corrupted temperature measurements. The accuracy and sensitivity to measurement uncertainty will be presented for each method.

  4. Theoretical research on rotational dispersion coefficient of fiber in turbulent shear flow of fiber suspension

    Institute of Scientific and Technical Information of China (English)

    GAO Zhen-yu; LIN Jian-zhong; LI Jun

    2007-01-01

    The rotational dispersion coefficient of the fiber in the turbulent shear flow of fiber suspension was studied theoretically. The function of correlation moment between the different fluctuating velocity gradients of the flow was built firstly. Then the expression, dependent on the characteristic length, time, velocity and a dimensionless parameter related to the effect of wall, of rotational dispersion coefficient is derived. The derived expression of rotational dispersion coefficient can be employed to the inhomogeneous and non-isotropic turbulent flows. Furthermore it can be expanded to three-dimensional turbulent flows and serves the theoretical basis for solving the turbulent flow of fiber suspension.

  5. Influence of two-drug combination therapy on nerve conduction velocity and hemorheology in patients with diabetic pe-ripheral neuropathy%两种药物联合治疗对糖尿病周围神经病变患者神经传导速度及血流变学的影响

    Institute of Scientific and Technical Information of China (English)

    刘丛华; 宁金堂

    2014-01-01

    目的:探讨丹参川穹嗪联合甲钴胺对糖尿病周围神经病变患者神经传导速度及血流变学的影响。方法将84例糖尿病周围神经病变患者随机分成观察组与对照组,每组42例。两组患者均严格控制血糖,观察组患者给予丹参川穹嗪联合甲钴胺静脉滴注治疗,对照组给予甲钴胺静脉滴注治疗,两组疗程均为4周。观察两组患者临床疗效、神经传导速度及血流变学的变化。结果观察组患者总有效率、感觉正中神通经、腓神经传导速度、运动正中神经、腓神经传导速度、血管内径变化率明显高于对照组;空腹血糖、总胆固醇(TC)、三酰甘油(TG)、血浆黏度、高切黏度、低切黏度、收缩期血管峰值血流速度(PS V )、内膜中层厚度(IM T )、管径狭窄率均明显低于对照组(P<0.05)。结论丹参川穹嗪联合甲钴胺治疗糖尿病周围神经病变患者临床疗效明显,有效提高神经传导速度,改善血液流变学状态。%Objective To study the influence of Danshen ligustrazin combined with mecobalamine on the nerve conduction velocity and hemorheology in the patients with diabetic peripheral neuropathy .Methods 84 patients with diabetic peripheral neuropathy were divided into the observation group and the control group ,42 cases in each group . The blood sugar in the two group was strictly controlled .The observation group was given Danshen ligustrazin com-bined with mecobalamine by intravenous drip ,while the control group was given intravenous drip of mecobalamine with the treatment course of 4 weeks .The clinical efficacy and the change of nerve the conduction velocity and hemor-rheology were observed in the two groups .Results The total effective rate ,conduction velocity of median and pero-neal sensory nerve ,conduction velocity of median and peroneal motor nerve and change rate of blood vessel diameter in the observation group were

  6. Vacuum fiber-fiber coupler

    Science.gov (United States)

    Heinrici, Axel; Bjelajac, Goran; Jonkers, Jeroen; Jakobs, Stefan; Olschok, Simon; Reisgen, Uwe

    2017-02-01

    Research and development carried out by the ISF Welding and Joining Institute of RWTH Aachen University has proven that combining high power laser and low vacuum atmosphere provides a welding performance and quality, which is comparable to electron beam welding. The developed welding machines are still using a beam forming which takes place outside the vacuum and the focusing laser beam has to be introduced to the vacuum via a suitable window. This inflexible design spoils much of the flexibility of modern laser welding. With the target to bring a compact, lightweight flying optics with flexible laser transport fibers into vacuum chambers, a high power fiber-fiber coupler has been adapted by II-VI HIGHYAG that includes a reliable vacuum interface. The vacuum-fiber-fiber coupler (V-FFC) is tested with up to 16 kW sustained laser power and the design is flexible in terms of a wide variety of laser fiber plug systems and vacuum flanges. All that is needed to implement the V-FFC towards an existing or planned vacuum chamber is an aperture of at least 100 mm (4 inch) diameter with any type of vacuum or pressure flange. The V-FFC has a state-of-the-art safety interface which allows for fast fiber breakage detection for both fibers (as supported by fibers) by electric wire breakage and short circuit detection. Moreover, the System also provides connectors for cooling and electric signals for the laser beam optics inside the vacuum. The V-FFC has all necessary adjustment options for coupling the laser radiation to the receiving fiber.

  7. Making bulk-conductive glass microchannel plates

    Science.gov (United States)

    Yi, Jay J. L.; Niu, Lihong

    2008-02-01

    The fabrication of microchannel plate (MCP) with bulk-conductive characteristics has been studied. Semiconducting clad glass and leachable core glass were used for drawing fibers and making MCP. Co-axial single fiber was drawn from a platinum double-crucible in an automatic fiberizing system, and the fibers were stacked and redrawn into multifiber by a special gripping mechanism. The multifibers were stacked again and the boule was made and sliced into discs. New MCPs were made after chemically leaching process without the traditional hydrogen firing. It was shown that bulk-conductive glass MCP can operate at higher voltage with lower noise.

  8. Conduct disorder

    Science.gov (United States)

    ... Conduct disorder is often linked to attention-deficit disorder . Conduct disorder also can be an early sign of ... child or teen has a history of conduct disorder behaviors. A physical examination and blood tests can help ...

  9. Moisture content effect on ultrasonic velocity in Goupia glabra

    Directory of Open Access Journals (Sweden)

    Fabiana Goia Rosa de Oliveira

    2005-03-01

    Full Text Available This paper discusses the application of ultrasound waves on a Brazilian hardwood, Goupia glabra, to evaluate the sensitivity of the ultrasonic technique to the moisture content in wood. The velocity of ultrasonic wave is sensitive to the material's quality-determining factors; hence, this technique is an important industrial tool to improve the quality control of processes. The nature of the response of velocity of sound to changes in moisture content led us to conclude that moisture gradients during drying exert a dominating effect. The ultrasonic velocity was measured both parallel and perpendicular to the fibers of Goupia glabra during drying from green to 6% moisture content. The results of this study showed that velocity of ultrasonic waves is sensitive to changes in moisture content of lumber during drying. The velocity under dry conditions was always higher than the velocity under more humid conditions, in both directions of propagation.

  10. Monitoring Fiber Stress During Curing of Single Fiber Glass- and Graphite-Epoxy Composites

    Science.gov (United States)

    Madhukar, Madhu S.; Kosuri, Ranga P.; Bowles, Kenneth J.

    1994-01-01

    The difference in thermal expansion characteristics of epoxy matrices and graphite fibers can produce significant residual stresses in the fibers during curing of composite materials. Tests on single fiber glass-epoxy and graphite-epoxy composite specimens were conducted in which the glass and graphite fibers were preloaded in tension, and the epoxy matrix was cast around the fibers. The fiber tension was monitored while the matrix was placed around the fiber and subjected to the temperature-time curing cycle. Two mechanisms responsible for producing stress in embedded fibers were identified as matrix thermal expansion and contraction and matrix cure shrinkage. A simple analysis based on the change in fiber tension during the curing cycle was conducted to estimate the produced stresses. Experimental results on single fiber glass- and graphite-epoxy composites show that the fiber was subjected to significant tensile stresses when the temperature was raised from the first to the second dwell period. When initial fiber pretension is about 60 percent of the fiber failure load, these curing-induced stresses can cause tensile fracture of the embedded fiber.

  11. Wettability of a Single Carbon Fiber.

    Science.gov (United States)

    Qiu, Si; Fuentes, Carlos A; Zhang, Dongxing; Van Vuure, Aart Willem; Seveno, David

    2016-09-27

    Wettability as determined from contact angle measurements is a suitable parameter for characterizing the physical bonding of a polymer matrix and reinforcing fibers, but it is very challenging to measure the capillary force exerted by a probe liquid on a fiber accurately for very fine fibers such as single carbon fibers. Herein, we propose an innovative method for measuring dynamic contact angles with a tensiometer, considering both the intrinsic variability of the carbon fiber diameter and the extremely small amplitude of the capillary forces, allowing the measurement of reliable dynamic contact angles over a large range of contact line velocities. The analysis of the contact angle dynamics by the molecular-kinetic theory permits us to check the relevancy of the measured contact angles and to obtain the static contact angle value, improving the prospect of employing tensiometry to better understand the wetting behavior of carbon fibers.

  12. Electron microscopy study of refractory ceramic fibers.

    Science.gov (United States)

    MacKinnon, P A; Lentz, T J; Rice, C H; Lockey, J E; Lemasters, G K; Gartside, P S

    2001-10-01

    In epidemiological studies designed to identify potential health risks of exposures to synthetic vitreous fibers, the characterization of airborne fiber dimensions may be essential for assessing mechanisms of fiber toxicity. Toward this end, air sampling was conducted as part of an industry-wide study of workers potentially exposed to airborne fibrous dusts during the manufacture of refractory ceramic fibers (RCF) and RCF products. Analyses of a subset of samples obtained on the sample filter as well as on the conductive sampling cowl were performed using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to characterize dimensions of airborne fibers. Comparison was made of bivariate fiber size distributions (length and diameter) from air samples analyzed by SEM and by TEM techniques. Results of the analyses indicate that RCF size distributions include fibers small enough in diameter ( 60 microm) may go undetected by TEM, as evidenced by the proportion of fibers in this category for TEM and SEM analyses (1% and 5%, respectively). Limitations of the microscopic techniques and differences in fiber-sizing rules for each method are believed to have contributed to the variation among fiber-sizing results. It was concluded from these data that further attempts to characterize RCF exposure in manufacturing and related operations should include analysis by TEM and SEM, since the smallest diameter fibers are not resolved with SEM and the fibers of longer length are not sized by TEM.

  13. The Transport Properties of Activated Carbon Fibers

    Science.gov (United States)

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  14. Dietary fiber.

    Science.gov (United States)

    Madar, Z; Thorne, R

    1987-01-01

    Studies done on dietary fiber (DF) over the past five years are presented in this Review. The involvement of dietary fiber in the control of plasma glucose and lipid levels is now established. Two dietary fiber sources (soybean and fenugreek) were studied in our laboratory and are discussed herein. These sources were found to be potentially beneficial in the reduction of plasma glucose in non-insulin dependent diabetes mellitus subjects. They are shown to be acceptable by human subjects and are easy to use either in a mixture of milk products and in cooking. The mechanism by which dietary fiber alters the nutrient absorption is also discussed. The effect of DF on gastric emptying, transit time, adsorption and glucose transport may contribute to reducing plasma glucose and lipid levels. DF was found to be effective in controlling blood glucose and lipid levels of pregnant diabetic women. Dietary fiber may also be potentially beneficial in the reduction of exogenous insulin requirements in these subjects. However, increased consumption of DF may cause adverse side effects; the binding capabilities of fiber may affect nutrient availability, particularly that of minerals and prolonged and high DF dosage supplementation must be regarded cautiously. This is particularly true when recommending such a diet for pregnant or lactating women, children or subjects with nutritional disorders. Physiological effects of DF appear to depend heavily on the source and composition of fiber. Using a combination of DF from a variety of sources may reduce the actual mass of fiber required to obtain the desired metabolic effects and will result in a more palatable diet. Previously observed problems, such as excess flatus, diarrhea and mineral malabsorption would also be minimized.

  15. EFFECT OF VELOCITY ON DUCTILITY UNDER HIGH VELOCITY FORMING

    Institute of Scientific and Technical Information of China (English)

    LI Zhong; LI Chunfeng

    2007-01-01

    The ring expansion procedures over various forming velocities are calculated with ANSYS software in order to show the effect of forming velocity on ductility of rate insensitive materials. Ring expansion procedures are simplified to one-dimensional tension by constraining the radial deformation, with element birth and death method, fracture problem of circular ring are considered. The calculated results show that for insensitive materials of 1060 aluminum and 3A21 aluminum alloy, fracture strain increases corresponding to the increase of forming velocity. This trend agrees well with experimental results, and indicates inertia is the key factor to affect ductility; With element birth and death methods, fracture problems can be solved effectively. Experimental studies on formability of tubular workpieces are also conducted, experimental results show that the formability of 1060 aluminum and 3A21 aluminum alloy under electromagnetic forming is higher than that under quasistatic forming, according to the characteristics of electromagnetic forming, the forming limit diagrams of the two materials tube are also built respectively, this is very important to promote the development of electromagnetic forming and guide the engineering practices.

  16. Superluminal Recession Velocities

    CERN Document Server

    Davis, T M; Davis, Tamara M.; Lineweaver, Charles H.

    2000-01-01

    Hubble's Law, v=HD (recession velocity is proportional to distance), is a theoretical result derived from the Friedmann-Robertson-Walker metric. v=HD applies at least as far as the particle horizon and in principle for all distances. Thus, galaxies with distances greater than D=c/H are receding from us with velocities greater than the speed of light and superluminal recession is a fundamental part of the general relativistic description of the expanding universe. This apparent contradiction of special relativity (SR) is often mistakenly remedied by converting redshift to velocity using SR. Here we show that galaxies with recession velocities faster than the speed of light are observable and that in all viable cosmological models, galaxies above a redshift of three are receding superluminally.

  17. Extreme Velocity Wind Sensor

    Science.gov (United States)

    Perotti, Jose; Voska, Ned (Technical Monitor)

    2002-01-01

    This presentation provides an overview of the development of new hurricane wind sensor (Extreme Velocity Wind Sensor) for the Kennedy Space Center (KSC) which is designed to withstand winds of up to three hundred miles an hour. The proposed Extreme Velocity Wind Sensor contains no moveable components that would be exposed to extreme wind conditions. Topics covered include: need for new hurricane wind sensor, conceptual design, software applications, computational fluid dynamic simulations of design concept, preliminary performance tests, and project status.

  18. Thermoelectric Properties of Conducting Polymers

    Science.gov (United States)

    1994-07-01

    conductivity of highly ordered pyrolytic graphite and benzene-derived graphite fiber. For a heat treament temperature (HTT) of 2900 °C, the unstretched film has... heat transmission is 5 important. The electrons responsible for electrical conductivity in metals also allow heat transmission by electrons, K. in Fig. 1... Heat transmission in polymers is by means of lattice vibrations, K, which do not contribute to electrical conductvity. Previous work with conducting

  19. Continual Cell Deformation Induced via Attachment to Oriented Fibers Enhances Fibroblast Cell Migration

    Science.gov (United States)

    Qin, Sisi; Ricotta, Vincent; Simon, Marcia; Clark, Richard A. F.; Rafailovich, Miriam H.

    2015-01-01

    Fibroblast migration is critical to the wound healing process. In vivo, migration occurs on fibrillar substrates, and previous observations have shown that a significant time lag exists before the onset of granulation tissue. We therefore conducted a series of experiments to understand the impact of both fibrillar morphology and migration time. Substrate topography was first shown to have a profound influence. Fibroblasts preferentially attach to fibrillar surfaces, and orient their cytoplasm for maximal contact with the fiber edge. In the case of en-mass cell migration out of an agarose droplet, fibroblasts on flat surfaces emerged with an enhanced velocity, v = 52μm/h, that decreases to the single cell value, v = 28μm/h within 24 hours and remained constant for at least four days. Fibroblasts emerging on fibrillar surfaces emerged with the single cell velocity, which remained constant for the first 24 hours and then increased reaching a plateau with more than twice the initial velocity within the next three days. The focal adhesions were distributed uniformly in cells on flat surfaces, while on the fibrillar surface they were clustered along the cell periphery. Furthermore, the number of focal adhesions for the cells on the flat surfaces remained constant, while it decreased on the fibrillar surface during the next three days. The deformation of the cell nuclei was found to be 50% larger on the fiber surfaces for the first 24 hours. While the mean deformation remained constant on the flat surface, it increased for the next three days by 24% in cells on fibers. On the fourth day, large actin/myosin fibers formed in cells on fibrillar surfaces only and coincided with a change from the standard migration mechanism involving extension of lamellipodia, and retraction of the rear, to one involving strong contractions oriented along the fibers and centered about the nucleus. PMID:25774792

  20. Continual cell deformation induced via attachment to oriented fibers enhances fibroblast cell migration.

    Directory of Open Access Journals (Sweden)

    Sisi Qin

    Full Text Available Fibroblast migration is critical to the wound healing process. In vivo, migration occurs on fibrillar substrates, and previous observations have shown that a significant time lag exists before the onset of granulation tissue. We therefore conducted a series of experiments to understand the impact of both fibrillar morphology and migration time. Substrate topography was first shown to have a profound influence. Fibroblasts preferentially attach to fibrillar surfaces, and orient their cytoplasm for maximal contact with the fiber edge. In the case of en-mass cell migration out of an agarose droplet, fibroblasts on flat surfaces emerged with an enhanced velocity, v = 52μm/h, that decreases to the single cell value, v = 28μm/h within 24 hours and remained constant for at least four days. Fibroblasts emerging on fibrillar surfaces emerged with the single cell velocity, which remained constant for the first 24 hours and then increased reaching a plateau with more than twice the initial velocity within the next three days. The focal adhesions were distributed uniformly in cells on flat surfaces, while on the fibrillar surface they were clustered along the cell periphery. Furthermore, the number of focal adhesions for the cells on the flat surfaces remained constant, while it decreased on the fibrillar surface during the next three days. The deformation of the cell nuclei was found to be 50% larger on the fiber surfaces for the first 24 hours. While the mean deformation remained constant on the flat surface, it increased for the next three days by 24% in cells on fibers. On the fourth day, large actin/myosin fibers formed in cells on fibrillar surfaces only and coincided with a change from the standard migration mechanism involving extension of lamellipodia, and retraction of the rear, to one involving strong contractions oriented along the fibers and centered about the nucleus.

  1. Investigations into the Effect of Current Velocity on Amidoxime-Based Polymeric Uranium Adsorbent Performance

    Energy Technology Data Exchange (ETDEWEB)

    Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Strivens, Jonathan E. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Wood, Jordana R. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Schlafer, Nicholas J. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Ladshaw, Austin [Georgia Inst. of Technology, Atlanta, GA (United States); Yiacoumi, Sotira [Georgia Inst. of Technology, Atlanta, GA (United States)

    2015-12-01

    The Fuel Resources Program at the U.S. Department of Energy’s (DOE), Office of Nuclear Energy (DOE-NE) is developing adsorbent technology to extract uranium from seawater. This technology is being developed to provide a sustainable and economically viable supply of uranium fuel for nuclear reactors (DOE, 2010). Among the key environmental variables to understand for adsorbent deployment in the coastal ocean is what effect flow-rates or linear velocity has on uranium adsorption capacity. The goal is to find a flow conditions that optimize uranium adsorption capacity in the shortest exposure time. Understanding these criteria will be critical in choosing a location for deployment of a marine adsorbent farm. The objective of this study was to identify at what linear velocity the adsorption kinetics for uranium extraction starts to drop off due to limitations in mass transport of uranium to the surface of the adsorbent fibers. Two independent laboratory-based experimental approaches using flow-through columns and recirculating flumes for adsorbent exposure were used to assess the effect of flow-rate (linear velocity) on the kinetic uptake of uranium on amidoxime-based polymeric adsorbent material. Time series observations over a 56 day period were conducted with flow-through columns over a 35-fold range in linear velocity from 0.29 to 10.2 cm/s, while the flume study was conducted over a narrower 11-fold range, from 0.48 to 5.52 cm/s. These ranges were specifically chosen to focus on the lower end of oceanic currents and expand above and below the linear velocity of ~ 2.5 cm/s adopted for marine testing of adsorbent material at PNNL.

  2. Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

    Science.gov (United States)

    Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

    2015-05-01

    Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey's equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29th International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160α, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.

  3. Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi [Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato [Research Center, Toyobo Co., LTD, 2-1-1 Katata, Otsu, Shiga 520-0292 (Japan)

    2015-05-22

    Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey’s equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29{sup th} International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160α, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.

  4. Carbon Fiber Biocompatibility for Implants

    Directory of Open Access Journals (Sweden)

    Richard Petersen

    2016-01-01

    Full Text Available Carbon fibers have multiple potential advantages in developing high-strength biomaterials with a density close to bone for better stress transfer and electrical properties that enhance tissue formation. As a breakthrough example in biomaterials, a 1.5 mm diameter bisphenol-epoxy/carbon-fiber-reinforced composite rod was compared for two weeks in a rat tibia model with a similar 1.5 mm diameter titanium-6-4 alloy screw manufactured to retain bone implants. Results showed that carbon-fiber-reinforced composite stimulated osseointegration inside the tibia bone marrow measured as percent bone area (PBA to a great extent when compared to the titanium-6-4 alloy at statistically significant levels. PBA increased significantly with the carbon-fiber composite over the titanium-6-4 alloy for distances from the implant surfaces of 0.1 mm at 77.7% vs. 19.3% (p < 10−8 and 0.8 mm at 41.6% vs. 19.5% (p < 10−4, respectively. The review focuses on carbon fiber properties that increased PBA for enhanced implant osseointegration. Carbon fibers acting as polymer coated electrically conducting micro-biocircuits appear to provide a biocompatible semi-antioxidant property to remove damaging electron free radicals from the surrounding implant surface. Further, carbon fibers by removing excess electrons produced from the cellular mitochondrial electron transport chain during periods of hypoxia perhaps stimulate bone cell recruitment by free-radical chemotactic influences. In addition, well-studied bioorganic cell actin carbon fiber growth would appear to interface in close contact with the carbon-fiber-reinforced composite implant. Resulting subsequent actin carbon fiber/implant carbon fiber contacts then could help in discharging the electron biological overloads through electrochemical gradients to lower negative charges and lower concentration.

  5. Biomass torrefaction characteristics in inert and oxidative atmospheres at various superficial velocities.

    Science.gov (United States)

    Chen, Wei-Hsin; Lu, Ke-Miao; Liu, Shih-Hsien; Tsai, Chi-Ming; Lee, Wen-Jhy; Lin, Ta-Chang

    2013-10-01

    The reaction characteristics of four biomass materials (i.e. oil palm fiber, coconut fiber, eucalyptus, and Cryptomeria japonica) with non-oxidative and oxidative torrefaction at various superficial velocities are investigated where nitrogen and air are used as carrier gases. Three torrefaction temperatures of 250, 300, and 350 °C are considered. At a given temperature, the solid yield of biomass is not affected by N2 superficial velocity, revealing that the thermal degradation is controlled by heat and mass transfer in biomass. Increasing air superficial velocity decreases the solid yield, especially in oil palm fiber and coconut fiber, implying that the torrefaction reaction of biomass is dominated by surface oxidation. There exists an upper limit of air superficial velocity in the decrement of solid yield, suggesting that beyond this limit the thermal degradation of biomass is no longer governed by surface oxidation, but rather is controlled by internal mass transport.

  6. LOW-VELOCITY IMPACT CHARACTERISTICS AND COMPRESSIVE STRENGTH AFTER IMPACT OF PLAIN WOVEN CARBON FIBER REINFORCED SILICON CARBIDE COMPOSITES%平纹编织碳纤维增强碳化硅复合材料低速冲击特性及冲击后的压缩强度

    Institute of Scientific and Technical Information of China (English)

    程起有; 童小燕; 陈刘定; 姚磊江; 李斌

    2009-01-01

    采用落锤冲击试验系统对平纹编织碳纤维增强碳化硅复合材料平板试样进行低速冲击,冲击能量为1.5~9J.冲击试验后,采用超声C扫描得到冲击损伤的大小.对含冲击损伤的试样进行压缩试验,通过与未冲击试样的压缩强度比较,得到冲击试样的剩余压缩强度.并对比了编织陶瓷基复合材料和树脂基复合材料的损伤阻抗和损伤容限.结果显示:随着冲击能量的增加,冲击力峰值、复合材料损伤面积和凹坑深度明显增加,到达峰值冲击力的时间减小.冲击能量的增加会导致冲击损伤面积的增加,而损伤面积的增加会导致剩余压缩强度的明显降低.相对于编织纤维增强树脂基复合材料,编织纤维增强陶瓷基复合材料的损伤阻抗较低,但损伤容限较高.%An experimental study was carried out to investigate the low-velocity impact characteristics and the strength after impact of plain woven carbon fiber reinforced silicon carbide composite.The test specimens were impacted using a dropped.weight impact test apparatus with an instrumented spherical tip.Non-destructive test methods were then utilized to characterize and quantify the impact damage.The residual compressive strengths of composites after impact were determined.The impact damage resistance and tolerance of woven fiber-reinforced ceramic.matrix composite were compared with those of woven fiber-reinforced polymer-matrix composite.The resuits show that a circular indentation on the impacted surface of specimens is formed in the impact.The peak load and the diameter and depth of indentation increase with the increase of the impact energy.The time reached to impact the peak load decrease with the increase of impact energy.According to observation of optical photographs and the image characteristics of samples obtained by ultrasonic C-scan after impact,the impact damage areas increase with the increase of impact energy.With the increase of impact

  7. Deposition of carbon nanotubes onto aramid fibers using as-received and chemically modified fibers

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Uicab, O. [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Avilés, F., E-mail: faviles@cicy.mx [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Gonzalez-Chi, P.I; Canché-Escamilla, G.; Duarte-Aranda, S. [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Yazdani-Pedram, M. [Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, S. Livingstone 1007, Independencia, Santiago (Chile); Toro, P. [Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Beauchef 850, Santiago (Chile); Gamboa, F. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Mérida, Depto. de Física Aplicada, Km. 6 Antigua Carretera a Progreso, 97310 Mérida, Yucatán (Mexico); Mazo, M.A.; Nistal, A.; Rubio, J. [Instituto de Cerámica y Vidrio (ICV-CSIC), Kelsen 5, 28049 Madrid (Spain)

    2016-11-01

    Highlights: • The surface of aramid fibers was functionalized by two acid treatments. • The treatment based on HNO{sub 3}/H{sub 2}SO{sub 4} reduced the mechanical properties of the fibers. • CNTs were deposited on the aramid fibers, reaching electrical conductivity. • Homogeneous CNT distribution was achieved by using pristine fibers or chlorosulfonic acid. - Abstract: Multiwall carbon nanotubes (MWCNTs) oxidized by an acid treatment were deposited on the surface of as-received commercial aramid fibers containing a surface coating (“sizing”), and fibers modified by either a chlorosulfonic treatment or a mixture of nitric and sulfuric acids. The surface of the aramid fiber activated by the chemical treatments presents increasing density of CO, COOH and OH functional groups. However, these chemical treatments reduced the tensile mechanical properties of the fibers, especially when the nitric and sulfuric acid mixture was used. Characterization of the MWCNTs deposited on the fiber surface was conducted by scanning electron microscopy, Raman spectroscopy mapping and X-ray photoelectron spectroscopy. These characterizations showed higher areal concentration and more homogeneous distribution of MWCNTs over the aramid fibers for as-received fibers and for those modified with chlorosulfonic acid, suggesting the existence of interaction between the oxidized MWCNTs and the fiber coating. The electrical resistance of the MWCNT-modified aramid yarns comprising ∼1000 individual fibers was in the order of MΩ/cm, which renders multifunctional properties.

  8. Detailed Measurement of Horizontal Groundwater Velocities Without a Borehole

    Science.gov (United States)

    Bakker, M.; Calje, R.; Van der Made, K. J.; Schaars, F.

    2014-12-01

    A new methodology has been developed to measure horizontal groundwater velocities in unconsolidated aquifers. Groundwater velocities are measured with a heat tracer experiment. Temperature is measured along fiber optic cables using a Distributed Temperature Sensing (DTS) system. Fiber optic cables and a separate heating cable are pushed into the ground to depths of tens of meters. The groundwater is heated with the heating cable and the response is measured along several nearby fiber optic cables. The measured temperature responses are used to estimate the distribution of the magnitude and direction of the horizontal groundwater velocity over the entire depth of the cables. The methodology has been applied in a phreatic aquifer in the dune area along the Dutch coast. Significant variations of groundwater velocities with depth were observed even though the dune sand is relatively homogeneous. Major advantages of the new methodology are that the fiber optic cables are in direct contact with the groundwater and that the cables and installation are relatively cheap. No expensive boreholes are needed and consequently measurements are not affected by movement and mixing of water inside a borehole.

  9. Deformation of a flexible fiber in a viscous flow past an obstacle

    CERN Document Server

    Lopez, H M; Auradou, H; D'Angelo, M V

    2015-01-01

    We study the deformation and transport of elastic fibers in a viscous Hele-Shaw flow with curved streamlines. The variations of the global velocity and orientation of the fiber follow closely those of the local flow velocity. The ratios of the curvatures of the fibers by the corresponding curvatures of the streamlines reflect a balance between elastic and viscous forces: this ratio is shown experimentally to be determined by a dimensionless {\\it Sperm number} $Sp$ combining the characteristic parameters of the flow (transverse velocity gradient, viscosity, fiber diameter/cell gap ratio) and those of the fiber (diameter, effective length, Young's modulus). For short fibers, the effective length is that of the fiber; for long ones, it is equal to the transverse characteristic length of the flow. For $S\\_p \\lesssim 250$, the ratio of the curvatures increases linearly with $Sp$; For $S\\_p \\gtrsim 250$, the fiber reaches the same curvature as the streamlines.

  10. Velocities in Solar Pores

    Science.gov (United States)

    Balasubramaniam, K. S.; Keil, S. L.; Smaldone, L. A.

    1996-05-01

    We investigate the three dimensional structure of solar pores and their surroundings using high spatial and spectral resolution data. We present evidence that surface velocities decrease around pores with a corresponding increase in the line-of-sight (LOS) velocities. LOS velocities in pores increase with the strength of the magnetic field. Surface velocities show convergence toward a weak downflow which appear to trace boundaries resembling meso-granular and super granular flows. The observed magnetic fields in the pores appear near these boundaries. We analyze the vertical velocity structure in pores and show that they generally have downflows decreasing exponentially with height, with a scale height of about 90 km. Evidence is also presented for the expanding nature of flux tubes. Finally we describe a phenomenological model for pores. This work was supported by AFOSR Task 2311G3. LAS was partially supported by the Progetto Nazionale Astrofisica e Fisica Cosmica of MURST and Scambi Internazionali of the Universita degli Studi di Napoli Frederico II. National Solar Observatory, NOAO, is operated for the National Science Foundation by AURA, Inc.

  11. Low Velocity Impact Response Analysis of Shape Memory Alloy Reinforced Composite Beam

    Institute of Scientific and Technical Information of China (English)

    WU Yongdong; ZHONG Weifang; WU Guorong; ZOU Jing

    2005-01-01

    The low velocity impact responses of shape memory alloy ( SMA ) reinforced composite beams were analyzed by employing the finite element method. The finite element dynamic equation was solved by the Newmark direct integration method, the impact contact force was determined using the Hertzian contact law, and the influence of SMA fibers on stiffness matrix is studied. Numerical results show that the SMA fibers can effectively improve the low velocity impact response property of composite beam.

  12. Quantitative velocity modulation spectroscopy

    Science.gov (United States)

    Hodges, James N.; McCall, Benjamin J.

    2016-05-01

    Velocity Modulation Spectroscopy (VMS) is arguably the most important development in the 20th century for spectroscopic study of molecular ions. For decades, interpretation of VMS lineshapes has presented challenges due to the intrinsic covariance of fit parameters including velocity modulation amplitude, linewidth, and intensity. This limitation has stifled the growth of this technique into the quantitative realm. In this work, we show that subtle changes in the lineshape can be used to help address this complexity. This allows for determination of the linewidth, intensity relative to other transitions, velocity modulation amplitude, and electric field strength in the positive column of a glow discharge. Additionally, we explain the large homogeneous component of the linewidth that has been previously described. Using this component, the ion mobility can be determined.

  13. Palm to finger ulnar sensory nerve conduction

    Directory of Open Access Journals (Sweden)

    Eduardo Davidowich

    2015-12-01

    Full Text Available Ulnar neuropathy at the wrist (UNW is rare, and always challenging to localize. To increase the sensitivity and specificity of the diagnosis of UNW many authors advocate the stimulation of the ulnar nerve (UN in the segment of the wrist and palm. The focus of this paper is to present a modified and simplified technique of sensory nerve conduction (SNC of the UN in the wrist and palm segments and demonstrate the validity of this technique in the study of five cases of type III UNW. The SNC of UN was performed antidromically with fifth finger ring recording electrodes. The UN was stimulated 14 cm proximal to the active electrode (the standard way and 7 cm proximal to the active electrode. The normal data from amplitude and conduction velocity (CV ratios between the palm to finger and wrist to finger segments were obtained. Normal amplitude ratio was 1.4 to 0.76. Normal CV ratio was 0.8 to 1.23.We found evidences of abnormal SNAP amplitude ratio or substantial slowing of UN sensory fibers across the wrist in 5 of the 5 patients with electrophysiological-definite type III UNW.

  14. Palm to Finger Ulnar Sensory Nerve Conduction.

    Science.gov (United States)

    Davidowich, Eduardo; Nascimento, Osvaldo J M; Orsini, Marco; Pupe, Camila; Pessoa, Bruno; Bittar, Caroline; Pires, Karina Lebeis; Bruno, Carlos; Coutinho, Bruno Mattos; de Souza, Olivia Gameiro; Ribeiro, Pedro; Velasques, Bruna; Bittencourt, Juliana; Teixeira, Silmar; Bastos, Victor Hugo

    2015-12-29

    Ulnar neuropathy at the wrist (UNW) is rare, and always challenging to localize. To increase the sensitivity and specificity of the diagnosis of UNW many authors advocate the stimulation of the ulnar nerve (UN) in the segment of the wrist and palm. The focus of this paper is to present a modified and simplified technique of sensory nerve conduction (SNC) of the UN in the wrist and palm segments and demonstrate the validity of this technique in the study of five cases of type III UNW. The SNC of UN was performed antidromically with fifth finger ring recording electrodes. The UN was stimulated 14 cm proximal to the active electrode (the standard way) and 7 cm proximal to the active electrode. The normal data from amplitude and conduction velocity (CV) ratios between the palm to finger and wrist to finger segments were obtained. Normal amplitude ratio was 1.4 to 0.76. Normal CV ratio was 0.8 to 1.23.We found evidences of abnormal SNAP amplitude ratio or substantial slowing of UN sensory fibers across the wrist in 5 of the 5 patients with electrophysiological-definite type III UNW.

  15. Soluble vs. insoluble fiber

    Science.gov (United States)

    Insoluble vs. soluble fiber; Fiber - soluble vs. insoluble ... There are 2 different types of fiber -- soluble and insoluble. Both are important for health, digestion, and preventing diseases. Soluble fiber attracts water and turns to gel during digestion. ...

  16. Novel Hemispherical Scanner for a Coherent Fiber LIDAR System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SibellOptics proposes to develop an eye-safe, long-range, compact, versatile, all-fiber wind LIDAR system for atmospheric wind velocity measurement applications that...

  17. Long distance transmission through distributed erbium-doped fibers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Povlsen, Jørn Hedegaard; Bjarklev, Anders Overgaard

    1993-01-01

    High bit rate, all-optical long-distance transmission could be created through the combined use of loss-compensating gain in erbium-doped fibers and solitons. A detailed analysis of the distributed erbium-doped fiber, including the spectral-gain dependency, is combined with an optimum design...... of the transmission fiber and general bit-error-rate calculations. Changes in wavenumber, group velocity, and fiber dispersion due to erbium doping in a single-mode fiber are evaluated, and a reduction in bit-error rates due to the erbium spectral-gain profile is shown. Transmission through distributed erbium...

  18. Photovoltaic fibers

    Science.gov (United States)

    Gaudiana, Russell; Eckert, Robert; Cardone, John; Ryan, James; Montello, Alan

    2006-08-01

    It was realized early in the history of Konarka that the ability to produce fibers that generate power from solar energy could be applied to a wide variety of applications where fabrics are utilized currently. These applications include personal items such as jackets, shirts and hats, to architectural uses such as awnings, tents, large covers for cars, trucks and even doomed stadiums, to indoor furnishings such as window blinds, shades and drapes. They may also be used as small fabric patches or fiber bundles for powering or recharging batteries in small sensors. Power generating fabrics for clothing is of particular interest to the military where they would be used in uniforms and body armor where portable power is vital to field operations. In strong sunlight these power generating fabrics could be used as a primary source of energy, or they can be used in either direct sunlight or low light conditions to recharge batteries. Early in 2002, Konarka performed a series of proof-of-concept experiments to demonstrate the feasibility of building a photovoltaic cell using dye-sensitized titania and electrolyte on a metal wire core. The approach taken was based on the sequential coating processes used in making fiber optics, namely, a fiber core, e.g., a metal wire serving as the primary electrode, is passed through a series of vertically aligned coating cups. Each of the cups contains a coating fluid that has a specific function in the photocell. A second wire, used as the counter electrode, is brought into the process prior to entering the final coating cup. The latter contains a photopolymerizable, transparent cladding which hardens when passed through a UV chamber. Upon exiting the UV chamber, the finished PV fiber is spooled. Two hundred of foot lengths of PV fiber have been made using this process. When the fiber is exposed to visible radiation, it generates electrical power. The best efficiency exhibited by these fibers is 6% with an average value in the 4

  19. The Prescribed Velocity Method

    DEFF Research Database (Denmark)

    Nielsen, Peter Vilhelm

    The- velocity level in a room ventilated by jet ventilation is strongly influenced by the supply conditions. The momentum flow in the supply jets controls the air movement in the room and, therefore, it is very important that the inlet conditions and the numerical method can generate a satisfactory...... description of this momentum flow. The Prescribed Velocity Method is a practical method for the description of an Air Terminal Device which will save grid points close to the opening and ensure the right level of the momentum flow....

  20. Cirrus Crystal Terminal Velocities.

    Science.gov (United States)

    Heymsfield, Andrew J.; Iaquinta, Jean

    2000-04-01

    Cirrus crystal terminal velocities are of primary importance in determining the rate of transport of condensate from upper- to middle-tropospheric levels and profoundly influence the earth's radiation balance through their effect on the rate of buildup or decay of cirrus clouds. In this study, laboratory and field-based cirrus crystal drag coefficient data, as well as analytical descriptions of cirrus crystal shapes, are used to derive more physically based expressions for the velocities of cirrus crystals than have been available in the past.Polycrystals-often bullet rosettes-are shown to be the dominant crystal types in synoptically generated cirrus, with columns present in varying but relatively large percentages, depending on the cloud. The two critical parameters needed to calculate terminal velocity are the drag coefficient and the ratio of mass to cross-sectional area normal to their fall direction. Using measurements and calculations, it is shown that drag coefficients from theory and laboratory studies are applicable to crystals of the types found in cirrus. The ratio of the mass to area, which is shown to be relatively independent of the number of bullets in the rosette, is derived from an analytic model that represents bullet rosettes containing one to eight bullets in 19 primary geometric configurations. The ratio is also derived for columns. Using this information, a general set of equations is developed to calculate the terminal velocities and masses in terms of the aspect ratio (width divided by length), ice density, and rosette maximum dimension. Simple expressions for terminal velocity and mass as a function of bullet rosette maximum dimension are developed by incorporating new information on bullet aspect ratios.The general terminal velocity and mass relations are then applied to a case from the First International Satellite Cloud Climatology Project (ISCCP) Research Experiment (FIRE) 2, when size spectra from a balloon-borne ice crystal

  1. Superluminal Propagation in Er3+-doped Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    ZHUO Zhong-chang; SU Xue-mei; YU Yong-sen; ZHENG Wei; ZHANG Yu-shu

    2005-01-01

    The method to pump the FBG written into an Er3+-doped optical fiber is proposed to increase the group velocity of a probing pulse based on the facts that pump-induced process changes the refractive index and dispersion associated with the 4I15/2 -4I13/2 transition in Er3+-doped optical fiber. The system equations are derived. The effects of pump power and doping concentration on the group velocity are discussed.

  2. Electrical Properties of Carbon Fiber Support Systems

    CERN Document Server

    Cooper, W; Demarteau, M; Fast, J; Hanagaki, K; Johnson, M; Kuykendall, W; Lubatti, H; Matulik, M; Nomerotski, A; Quinn, B; Wang, J

    2005-01-01

    Carbon fiber support structures have become common elements of detector designs for high energy physics experiments. Carbon fiber has many mechanical advantages but it is also characterized by high conductivity, particularly at high frequency, with associated design issues. This paper discusses the elements required for sound electrical performance of silicon detectors employing carbon fiber support elements. Tests on carbon fiber structures are presented indicating that carbon fiber must be regarded as a conductor for the frequency region of 10 to 100 MHz. The general principles of grounding configurations involving carbon fiber structures will be discussed. To illustrate the design requirements, measurements performed with a silicon detector on a carbon fiber support structure at small radius are presented. A grounding scheme employing copper-kapton mesh circuits is described and shown to provide adequate and robust detector performance.

  3. Modeling Terminal Velocity

    Science.gov (United States)

    Brand, Neal; Quintanilla, John A.

    2013-01-01

    Using a simultaneously falling softball as a stopwatch, the terminal velocity of a whiffle ball can be obtained to surprisingly high accuracy with only common household equipment. This classroom activity engages students in an apparently daunting task that nevertheless is tractable, using a simple model and mathematical techniques at their…

  4. Fiber resources

    Science.gov (United States)

    P. J. Ince

    2004-01-01

    In economics, primary inputs or factors of production define the term ‘resources.’ Resources include land resources (plants, animals, and minerals), labor, capital, and entrepreneurship. Almost all pulp and paper fiber resources are plant materials obtained from trees or agricultural crops. These resources encompass plant materials harvested directly from the land (...

  5. Impact properties of aluminium - glass fiber reinforced plastics sandwich panels

    Directory of Open Access Journals (Sweden)

    Mathivanan Periasamy

    2012-06-01

    Full Text Available Aluminium - glass fiber reinforced plastics (GFRP sandwich panels are hybrid laminates consisting of GFRP bonded with thin aluminum sheets on either side. Such sandwich materials are increasingly used in airplane and automobile structures. Laminates with varying aluminium thickness fractions, fiber volume fractions and orientation in the layers of GFRP were fabricated by hand lay up method and evaluated for their impact performance by conducting drop weight tests under low velocity impacts. The impact energy required for initiating a crack in the outer aluminium layer as well as the energy required for perforation was recorded. The impact load-time history was also recorded to understand the failure behavior. The damage depth and the damage area were measured to evaluate the impact resistance. Optical photography and scanning electron micrographs were taken to visualize the crack and the damage zone. The bidirectional cross-ply hybrid laminate (CPHL has been found to exhibit better impact performance and damage resistance than the unidirectional hybrid laminate (UDHL. Increase in aluminium thickness fraction (Al tf and fiber volume fraction (Vf resulted in an increase in the impact energy required for cracking and perforation. On an overall basis, the sandwich panels exhibited better impact performance than the monolithic aluminium.

  6. Muscle fiber velocity and electromyographic signs of fatigue in fibromyalgia

    NARCIS (Netherlands)

    Klaver-Krol, Ewa G.; Rasker, Johannes J.; Henriquez, Nizare R.; Verheijen, Wilma G.; Zwarts, Machiel J.

    2012-01-01

    Introduction: Fibromyalgia (FM) is a disorder of widespread muscular pain. We investigated possible differences in surface electromyography (sEMG) in clinically unaffected muscle between patients with FM and controls. Methods: sEMG was performed on the biceps brachii muscle of 13 women with FM and 1

  7. Muscle fiber velocity and electromyographic signs of fatigue in fibromyalgia

    NARCIS (Netherlands)

    Klaver-Krol, Ewa G.; Rasker, Johannes J.; Henriquez, Nizare R.; Verheijen, Wilma G.; Zwarts, Machiel J.

    2012-01-01

    Introduction: Fibromyalgia (FM) is a disorder of widespread muscular pain. We investigated possible differences in surface electromyography (sEMG) in clinically unaffected muscle between patients with FM and controls. Methods: sEMG was performed on the biceps brachii muscle of 13 women with FM and 1

  8. Optimal non-circular fiber geometries for image scrambling in high-resolution spectrographs

    CERN Document Server

    Stürmer, Julian; Grimm, Stephan; Kalide, Andre; Sutherland, Adam P; Seifahrt, Andreas; Schuster, Kay; Bean, Jacob L; Quirrenbach, Andreas

    2016-01-01

    Optical fibers are a key component for high-resolution spectrographs to attain high precision in radial velocity measurements. We present a custom fiber with a novel core geometry - a 'D'-shape. From a theoretical standpoint, such a fiber should provide superior scrambling and modal noise mitigation, since unlike the commonly used circular and polygonal fiber cross sections, it shows chaotic scrambling. We report on the fabrication process of a test fiber and compare the optical properties, scrambling performance, and modal noise behavior of the D-fiber with those of common polygonal fibers.

  9. Ephaptic coupling of myelinated nerve fibers

    DEFF Research Database (Denmark)

    Binczak, S.; Eilbeck, J. C.; Scott, Alwyn C.

    2001-01-01

    Numerical predictions of a simple myelinated nerve fiber model are compared with theoretical results in the continuum and discrete limits, clarifying the nature of the conduction process on an isolated nerve axon. Since myelinated nerve fibers are often arranged in bundles, this model is used...... to study ephaptic (nonsynaptic) interactions between impulses on parallel fibers, which may play a functional role in neural processing. (C) 2001 Published by Elsevier Science B.V....

  10. Research of Degumming Process, Microstructure and Properties of Mulberry Fiber

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    More and more novel nature fibers are used in textiles. The natural fibers include banana fiber, pineapple fiber and bamboo fiber etc. In this paper, as a kind of novel natural fiber, mulberry fiber is studied. The chemical component of mulberry bast is tested and analyzed.Meanwhile, the degumming method and process of mulberry bast are studied. Chemical degumming experiments to investigate the influence of alkali concentration, alkali boiling time and sodium phosphate tribasic ratio to material are conducted. Consequently, optimum parameters are obtained. The crystallinity of mulberry fiber is tested by using X-ray line, and the photos of scanning electron microscope (SEM) are observed. Testing results of the fiber properties (e. g. fineness, tenacity, length and elongation)show that mulberry fiber can be spun blend with cotton.

  11. Thermography Used to Test Conductivity of Carbon Based Cloth

    Science.gov (United States)

    Craven, Paul

    2012-01-01

    Testing of the ability of carbon fiber to radiatively cool a heat source. The carbon fibers are attached to a heat source. The heat conducts into the fiber than along the fiber away from the heat source. The test are done in a vacuum chamber (10-5 Torr typical). The IR camera is viewing the fiber through a ZnSe window. A thermocouple (TC) in contact with the fiber is at the top right hand side of the area of interest and one is near the bottom. Thin shielding fins, seen edge on, are just above the top thermocouple.

  12. Wave propagation and group velocity

    CERN Document Server

    Brillouin, Léon

    1960-01-01

    Wave Propagation and Group Velocity contains papers on group velocity which were published during the First World War and are missing in many libraries. It introduces three different definitions of velocities: the group velocity of Lord Rayleigh, the signal velocity of Sommerfeld, and the velocity of energy transfer, which yields the rate of energy flow through a continuous wave and is strongly related to the characteristic impedance. These three velocities are identical for nonabsorbing media, but they differ considerably in an absorption band. Some examples are discussed in the last chapter

  13. Spectral Velocity Estimation in the Transverse Direction

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2013-01-01

    estimation scheme can reliably find the spectrum at 90, where a traditional estimator yields zero velocity. Measurements have been conducted with the SARUS experimental scanner and a BK 8820e convex array transducer (BK Medical, Herlev, Denmark). A CompuFlow 1000 (Shelley Automation, Inc, Toronto, Canada...

  14. Application of Fiber Optic Instrumentation

    Science.gov (United States)

    Richards, William Lance; Parker, Allen R., Jr.; Ko, William L.; Piazza, Anthony; Chan, Patrick

    2012-01-01

    Fiber optic sensing technology has emerged in recent years offering tremendous advantages over conventional aircraft instrumentation systems. The advantages of fiber optic sensors over their conventional counterparts are well established; they are lighter, smaller, and can provide enormous numbers of measurements at a fraction of the total sensor weight. After a brief overview of conventional and fiber-optic sensing technology, this paper presents an overview of the research that has been conducted at NASA Dryden Flight Research Center in recent years to advance this promising new technology. Research and development areas include system and algorithm development, sensor characterization and attachment, and real-time experimentally-derived parameter monitoring for ground- and flight-based applications. The vision of fiber optic smart structure technology is presented and its potential benefits to aerospace vehicles throughout the lifecycle, from preliminary design to final retirement, are presented.

  15. Fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser

    Science.gov (United States)

    Kuang, Zeyuang; Cheng, Linghao; Liang, Yizhi; Liang, Hao; Guan, Bai-Ou

    2015-07-01

    A fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser is demonstrated. The fiber grating laser produces two orthogonally polarized laser outputs with their frequency difference proportional to the intra-cavity birefringence. When the laser outputs are reflected from a moving targets, the laser frequencies will be shifted due to the Doppler effect. It shows that the frequency difference between the beat note of the laser outputs and the beat note of the reflected lasers is proportional to the velocity. The proposed fiber-optic Doppler velocimeter shows a high sensitivity of 0.64 MHz/m/s and is capable of measurement of wide range of velocity.

  16. Raman spectroscopy system with hollow fiber probes

    Science.gov (United States)

    Liu, Bing-hong; Shi, Yi-Wei

    2012-11-01

    A Raman remote spectroscopy system was realized using flexible hollow optical fiber as laser emittion and signal collection probes. A silver-coated hollow fiber has low-loss property and flat transmission characteristics in the visible wavelength regions. Compared with conventional silica optical fiber, little background fluorescence noise was observed with optical fiber as the probe, which would be of great advantages to the detection in low frequency Raman shift region. The complex filtering and focusing system was thus unnecessary. The Raman spectra of CaCO3 and PE were obtained by using the system and a reasonable signal to noise ratio was attained without any lens. Experiments with probes made of conventional silica optical fibers were also conducted for comparisons. Furthermore, a silver-coated hollow glass waveguide was used as sample cell to detect liquid phase sample. We used a 6 cm-long hollow fiber as the liquid cell and Butt-couplings with emitting and collecting fibers. Experiment results show that the system obtained high signal to noise ratio because of the longer optical length between sample and laser light. We also give the elementary theoretical analysis for the hollow fiber sample cell. The parameters of the fiber which would affect the system were discussed. Hollow fiber has shown to be a potential fiber probe or sample cell for Raman spectroscopy.

  17. Catalytic property of fiber media supported palladium containing alloy nanoparticles and electrospun ceramic fibers biodurability study

    Science.gov (United States)

    Shin, Hyeon Ung

    The nanoscale of the supporting fibers may provide enhancements such as restricting the migration of metal catalyst particles. In this work, palladium nanoparticle doped alumina fibers were electrospun into template submicron fibers. These fibers were calcined at temperatures between 650°C and 1150°C to vary the crystal structures of the calcined fibers with the Pd particle size. Higher calcination temperatures led to higher reaction temperatures from 250 to about 450°C for total conversion, indicating the effective reactivity of the fiber-supported catalysts decreased with increase in calcination temperature. Pd-Au alloy nanoparticle doped titania fibers were also fabricated using an electrospinning method and assembled into a fibrous porous medium structure by a vacuum molding process. In reactor tests, the fiber media with Pd-Au alloy nanoparticle catalyst had greater reactivity in conversion of NO and CO gases than that of fiber media with Pd monometallic catalyst alone, attributed to a lower activation energy of the Pd-Au catalyst particles. In carbon monoxide oxidation reaction tests, the results showed that the performance was optimal for a catalyst of composition Pd2Au1 molar ratio that was active at 125°C, which had higher dispersion of active components and better catalytic performance compared to monometallic particle Au/TiO 2 and Pd/TiO2 fiber media. Moreover, the improved reaction activity of Pd2Au1/TiO2 fiber medium was attributed to a decreased in the activation energy. Further experiments were conducted using the electrospun ceramic fibers biodurability study. The properties of nano-sized fiber structures have attracted the attention of recent research on ceramic nanostructures as nonwoven media for applications in hazardous chemical and high temperature environments. However, health and safety concerns of micro and nano scale ceramic materials have not been fully investigated. Little is known about the physicochemical effects of the properties

  18. Characterization of ecofriendly polyethylene fiber from plastic bag waste

    Science.gov (United States)

    Soekoco, Asril S.; Noerati, Komalasari, Maya; Kurniawan, Hananto, Agus

    2017-08-01

    This paper presents the characterization of fiber morphology, fiber count and tenacity of polyethylene fiber which is made from plastic bag waste. Recycling plastic bag waste into textile fiber has not developed yet. Plastic bag waste was recycled into fiber by melt spinning using laboratory scale melt spinning equipment with single orifice nozzle and plunger system. The basic principle of melt spinning is by melting materials and then extruding it through small orifice of a spinning nozzle to form fibers. Diameter and cross section shape of Recycled polyethylene fiber were obtained by using scanning electron microscope (SEM) instrumentation. Linear density of the recycled fiber were analyzed by calculation using denier and dTex formulation and The mechanical strength of the fibers was measured in accordance with the ASTM D 3379-75 standard. The cross section of recycled fiber is circular taking the shape of orifice. Fiber count of 303.75 denier has 1.84 g/denier tenacity and fiber count of 32.52 has 3.44 g/denier tenacity. This conditions is affected by the growth of polymer chain alignment when take-up axial velocity become faster. Recycled polyethylene fiber has a great potential application in non-apparel textile.

  19. Analysis of the Microstructure and Permeability of the Laminates with Different Fiber Volume Fraction

    Institute of Scientific and Technical Information of China (English)

    MA Yue; LI Wei; LIANG Zi-qing

    2008-01-01

    Microstmctures of laminates produced by epoxy/ carbon fibers with different fiber volume fraction were studied by analyzing the composite cross-sections. The main result of the compaction of reinforcement is the flatting of bundle shape, the reducing of gap and the embedment of bundles among each layer. The void content outside the bundle decreased sharply during the compoction until it is less than that inside the bundle when the fiber volume fraction is over 60%. The resin flow velocity in the fiber tow is 102-104 times greater than the flow velocity out the fiber tow no matter the capillary pressure is taken into account or not.

  20. Electrical Conductivity.

    Science.gov (United States)

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  1. Analysis of sampled fiber Bragg gratings in polarization-maintaining fiber

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel type of sampled fiber Bragg gratings (FBGs) written in polarization-maintaining fiber (PMF) is proposed.The reflection spectrum,time delay,and group velocity dispersion (GVD) of the gratings are analyzed.In addition,the reflection spectrum is optimized by apodization.The scheme of multi-wavelength output based on the gratings is proposed,which could be used as a multi-wavelength polarization filter in the density wavelength division multiplexed (DWDM) system.

  2. Guided wave propagation in porous unidirectional carbon fiber reinforced plastic

    Science.gov (United States)

    Dobmann, Nicolas; Bach, Martin

    2017-02-01

    Networks of piezoelectric transducers mounted on aircraft structures for Acousto Ultrasonics (AU) purposes are designed to be applied during the service life of the aircraft. The approach to integrate these sensor networks already during the manufacture of carbon fiber reinforced plastic (CFRP) host structures prompts ideas to achieve an additional benefit by their application for cure monitoring, thus extending their use to the manufacturing chain. This benefit could be extended even further if guided waves generated by AU sensor networks could be used for porosity testing extensively applied for CFRP aircraft structures. In light of this, an experimental study was conducted to investigate effects of porosity on the propagation of guided waves in a basic configuration of unidirectional CFRP. Several samples were manufactured at different porosity levels by variation of the processing pressure. Wave fields were acquired using an ultrasonic scanning device. In the present work, phase velocities are chosen as best measurable and quantifiable propagation feature and the approach for the analysis of phase velocities in porosity samples is outlined. First results are presented and discussed regarding the influence of porosity on guided wave phase velocity and basic applicability for porosity testing of aircraft structures.

  3. Intercalated hybrid graphite fiber composite

    Science.gov (United States)

    Gaier, James R. (Inventor)

    1993-01-01

    The invention is directed to a highly conductive lightweight hybrid material and methods of producing the same. The hybrid composite is obtained by weaving strands of a high strength carbon or graphite fiber into a fabric-like structure, depositing a layer of carbon onto the structure, heat treating the structure to graphitize the carbon layer, and intercalating the graphitic carbon layer structure. A laminate composite material useful for protection against lightning strikes comprises at least one layer of the hybrid material over at least one layer of high strength carbon or graphite fibers. The composite material of the present invention is compatible with matrix compounds, has a coefficient of thermal expansion which is the same as underlying fiber layers, and is resistant to galvanic corrosion in addition to being highly conductive. These materials are useful in the aerospace industry, in particular as lightning strike protection for airplanes.

  4. Transverse velocity shifts in protostellar jets: rotation or velocity asymmetries?

    CERN Document Server

    De Colle, Fabio; Riera, Angels

    2016-01-01

    Observations of several protostellar jets show systematic differences in radial velocity transverse to the jet propagation direction, which have been interpreted as evidence of rotation in the jets. In this paper we discuss the origin of these velocity shifts, and show that they could be originated by rotation in the flow, or by side to side asymmetries in the shock velocity, which could be due to asymmetries in the jet ejection velocity/density or in the ambient medium. For typical poloidal jet velocities (~ 100-200 km/s), an asymmetry >~ 10% can produce velocity shifts comparable to those observed. We also present three dimensional numerical simulations of rotating, precessing and asymmetric jets, and show that, even though for a given jet there is a clear degeneracy between these effects, a statistical analysis of jets with different inclination angles can help to distinguish between the alternative origins of transverse velocity shifts. Our analysis indicate that side to side velocities asymmetries could ...

  5. Carbon black and vapor grown carbon fibers binary conductive additive for the Li{sub 1.18}Co{sub 0.15}Ni{sub 0.15}Mn{sub 0.52}O{sub 2} electrodes for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Bian, Xiaofei; Fu, Qiang; Qiu, Chengguang; Bie, Xiaofei; Du, Fei; Wang, Yuhui; Zhang, Yongquan; Qiu, Hailong [Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun 130012 (China); Chen, Gang [Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun 130012 (China); State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Wei, Yingjin, E-mail: yjwei@jlu.edu.cn [Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun 130012 (China)

    2015-04-15

    Carbon black (CB) and vapor-grown carbon fibers (VGCFs) are used as conductive additives for the Li{sub 1.18}Co{sub 0.15}Ni{sub 0.15}Mn{sub 0.52}O{sub 2} electrodes for Li-ion batteries. The fibrous VGCFs can bridge the isolated Li{sub 1.18}Ni{sub 0.15}Co{sub 0.15}Mn{sub 0.52}O{sub 2} regions, thus construct an effective conductive network for electron transport. In addition, incorporation of CB and VGCFs can improve the electrochemical kinetics of the cathode material by retarding the harmful side reactions, promoting the charge transfer reactions and increasing the apparent lithium diffusion coefficient. In all electrodes under investigation, the one prepared with 3 wt.% of VGCFs and 12 wt.% of CB shows the largest discharge capacity of 252 mAh g{sup −1} at the 0.2C rate with excellent capacity retention and rate capability. - Highlights: • CB/VGCFs binary conductive additive is used for Li-excess layered cathode electrode. • The binary conductive additive constructs a continuous network for electron transport. • The binary conductive additive improves the electrochemical kinetics of the electrode. • Improved electrochemical performance is gained using the binary conductive additive.

  6. Beaded Fiber Mats of PVA Containing Unsaturated Heteropoly Salt

    Institute of Scientific and Technical Information of China (English)

    Guo Cheng YANG; Yan PAN; Jian GONG; Chang Lu SHAO; Shang Bin WEN; Chen SHAO; Lun Yu QU

    2004-01-01

    Poly(vinyl alcohol) (PVA) fiber mats containing unsaturated heteropoly salt was prepared for the first time. IR, X-ray diffraction and SEM photographs characterized the beaded fiber mats.The viscoelasticity and the conductivity of the solution were the key factors that influence the formation of the beaded fiber mats.

  7. Effect of a new aldose reductase inhibitor, 8'-chloro-2',3'-dihydrospiro [pyrrolidine-3,6'(5'H)-pyrrolo[1,2,3-de] [1,4]benzoxazine]-2,5,5'- trione (ADN-138), on delayed motor nerve conduction velocity in streptozotocin-diabetic rats.

    Science.gov (United States)

    Hirata, Y; Fujimori, S; Okada, K

    1988-02-01

    The effects of a chemically new type of aldose reductase inhibitor, ADN-138, on delayed motor nerve conduction velocity (MNCV) and sciatic nerve sorbitol, fructose and myo-inositol levels were studied in streptozotocin-diabetic rats. MNCV in rats was significantly delayed after 3 weeks of diabetes and ADN-138 treatment was started at this point. Treatment of diabetics with ADN-138 at 5 and 20 but not 1 mg/kg/d for 3 weeks resulted in a significant increase in MNCV and reduced sorbitol levels to or below those of nondiabetic controls. However, fructose, though decreased in a dose-dependent manner, was not normalized. The reference drug, Sorbinil, showed similar effects on them. After the 3 weeks of ADN-138(20 mg/kg/d) treatment, diabetics were left on ADN-138 or continued further to be treated with it for 3 weeks. The withdrawal of ADN-138 prevented a further increase in MNCV and restored sorbitol and fructose to nontreated diabetic levels, and myo-inositol levels declined. In contrast, the ADN-138-continued group kept improving its MNCV and normalized sorbitol and myo-inositol. These results suggest that polyol accumulation is responsible for delayed MNCV and that the action of ADN-138 on MNCV reflected reversibility of metabolic function in diabetics.

  8. Dark Matter Velocity Spectroscopy.

    Science.gov (United States)

    Speckhard, Eric G; Ng, Kenny C Y; Beacom, John F; Laha, Ranjan

    2016-01-22

    Dark matter decays or annihilations that produce linelike spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming experiments will have the precision needed. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications.

  9. Minimum Length - Maximum Velocity

    CERN Document Server

    Panes, Boris

    2011-01-01

    We study a framework where the hypothesis of a minimum length in space-time is complemented with the notion of reference frame invariance. It turns out natural to interpret the action of the obtained reference frame transformations in the context of doubly special relativity. As a consequence of this formalism we find interesting connections between the minimum length properties and the modified velocity-energy relation for ultra-relativistic particles. For example we can predict the ratio between the minimum lengths in space and time using the results from OPERA about superluminal neutrinos.

  10. Dark Matter Velocity Spectroscopy

    CERN Document Server

    Speckhard, Eric G; Beacom, John F; Laha, Ranjan

    2016-01-01

    Dark matter decays or annihilations that produce line-like spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming and proposed experiments will make significant improvements. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications.

  11. Constraints on Shear Velocity in the Cratonic Upper Mantle From Rayleigh Wave Phase Velocity

    Science.gov (United States)

    Hirsch, A. C.; Dalton, C. A.

    2014-12-01

    In recent years, the prevailing notion of Precambrian continental lithosphere as a thick boundary layer (200-300 km), defined by a depleted composition and a steady-state conductively cooled temperature structure, has been challenged by several lines of seismological evidence. One, profiles of shear velocity with depth beneath cratons exhibit lower wave speed at shallow depths and higher wave speed at greater depths than can be explained by temperature alone. These profiles are also characterized by positive or flat velocity gradients with depth and anomalously high attenuation in the uppermost mantle, both of which are difficult to reconcile with the low temperatures and large thermal gradient expected with a thermal boundary layer. Two, body-wave receiver-function studies have detected a mid-lithospheric discontinuity that requires a large and abrupt velocity decrease with depth in cratonic regions that cannot be achieved by thermal gradients alone. Here, we used forward-modeling to identify the suite of shear-velocity profiles that are consistent with phase-velocity observations made for Rayleigh waves that primarily traversed cratons in North America, South America, Africa, and Australia. We considered two approaches; with the first, depth profiles of shear velocity were predicted from thermal models of the cratonic upper mantle that correspond to a range of assumed values of mantle potential temperature, surface heat flow, and radiogenic heat production in the crust and upper mantle. With the second approach, depth profiles of shear velocity were randomly generated. In both cases, Rayleigh wave phase velocity was calculated from the Earth models and compared to the observed values. We show that it is very difficult to match the observations with an Earth model containing a low-velocity zone in the upper mantle; instead, the best-fit models contain a flat or positive velocity gradient with depth. We explore the implications of this result for the thermal and

  12. DUCTILITY BEHAVIOR FIBER REINFORCED CONCRETE BEAMS STRENGTHENED WITH EXTERNALLY BONDED GLASS FIBER REINFORCED POLYMER LAMINATES

    Directory of Open Access Journals (Sweden)

    Mariappan Mahalingam

    2013-01-01

    Full Text Available The study presents the results of an experimental investigation conducted on Steel Fiber Reinforced Concrete (SFRC beams with externally bonded Glass Fiber Reinforced Polymer (GFRP laminates with a view to study their strength and ductility. A total of ten beams, 150×250 mm in cross-section were tested in the laboratory over an effective span of 2800 mm. Three fiber reinforced concrete beams were used as reference beams. Six fiber reinforced concrete beams were provided with externally bonded GFRP laminates. One concrete beam was left virgin without any fiber reinforcement and external GFRP laminates. All the beams were tested until failure. The variables considered included volume fraction of fiber reinforcement and stiffness of GFRP laminates. The static responses of all the beams were evaluated in terms of strength, stiffness and ductility. The test results show that the beams provided with externally bonded GFRP laminates exhibit improved performance over the beams with internal fiber reinforcement.

  13. Conduct disorders

    NARCIS (Netherlands)

    Buitelaar, J.K.; Smeets, K.C.; Herpers, P.; Scheepers, F.; Glennon, J.; Rommelse, N.N.J.

    2013-01-01

    Conduct disorder (CD) is a frequently occurring psychiatric disorder characterized by a persistent pattern of aggressive and non-aggressive rule breaking antisocial behaviours that lead to considerable burden for the patients themselves, their family and society. This review paper updates diagnostic

  14. Fiber-Optic Optical-Microwave Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Used to conduct programs of basic science and applied research in the development of laser sources, high-power fiber amplifiers, photonic control of phased...

  15. Fiber-reinforced sand strength and dilation characteristics

    Directory of Open Access Journals (Sweden)

    Hesham M. Eldesouky

    2016-06-01

    Full Text Available Randomly distributed fiber reinforcement is used to provide an isotropic increase in the sand shear strength. The previous studies were not consistent regarding the fibers effect on the volumetric change behavior of fiber-reinforced sand. In this paper, direct shear tests are conducted on 108 specimens to investigate the effects of the fibers content, relative density, normal stress and moisture content on the shear strength and volumetric change behaviors of fiber-reinforced sand. The study investigates also the possibility of using dry fiber-reinforced sand as an alternative to heavily compacted unreinforced moist sand. The results indicate that the fibers inclusion increases the shear strength and dilation of sand. Moisture suppresses the fibers effect on the peak and post-peak shear strengths, and dilation. Dry loose fiber-reinforced sand achieves the same shear strength of heavily compacted unreinforced moist sand, yet at more than double the horizontal displacement.

  16. Determination of Muzzle Velocity Loss by Bore Wear Pattern

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-xin; WANG Gui-yu

    2007-01-01

    A method to determine muzzle velocity loss according to the actual measured bore wear pattern is proposed.Therefore, it is unnecessary to conduct live firing and other experiments for determination of muzzle velocity loss. It has been applied to a national military standard since July 1, 2004.

  17. Ultrasonic velocity and attenuation anisotropy of shales, Whitby, United Kingdom

    NARCIS (Netherlands)

    Zhubayev, A.; Houben, M.E.; Smeulders, D.M.J.; Barnhoorn, A.

    2015-01-01

    We have conducted ultrasonic experiments, between 0.3 and 1 MHz, to measure velocity and attenuation (Q−1) anisotropy of P- and S-waves in dry Whitby Mudstone samples as a function of stress. We found the degree of anisotropy to be as large as 70% for velocity and attenuation. The sensitivity of P-w

  18. Ultrasonic velocity and attenuation anisotropy of shales, Whitby, United Kingdom

    NARCIS (Netherlands)

    Zhubayev, Alimzhan; Houben, M.E.; Smeulders, David; Barnhoorn, A.

    2016-01-01

    We have conducted ultrasonic experiments, between 0.3 and 1 MHz, to measure velocity and attenuation (Q−1) anisotropy of P- and S-waves in dry Whitby Mudstone samples as a function of stress. We found the degree of anisotropy to be as large as 70% for velocity and attenuation. The sensitivity of P-w

  19. Smart Cellulose Fibers Coated with Carbon Nanotube Networks

    OpenAIRE

    Haisong Qi; Jianwen Liu; Edith Mäder

    2014-01-01

    Smart multi-walled carbon nanotube (MWCNT)-coated cellulose fibers with a unique sensing ability were manufactured by a simple dip coating process. The formation of electrically-conducting MWCNT networks on cellulose mono- and multi-filament fiber surfaces was confirmed by electrical resistance measurements and visualized by scanning electron microscopy. The interaction between MWCNT networks and cellulose fiber was investigated by Raman spectroscopy. The piezoresistivity of these fibers fo...

  20. Velocity centroids as tracers of the turbulent velocity statistics

    CERN Document Server

    Lazarian, A E A

    2004-01-01

    We use the results of magnetohydrodynamic (MHD) simulations to emulate spectroscopic observations, and produce maps of variations of velocity centroids to study their scaling properties. We compare them with those of the underlying velocity field, and analytic predictions presented in a previous paper (Lazarian & Esquivel 2003). We tested, with success, a criteria for recovering velocity statistics from velocity centroids derived in our previous work. That is, if >> (where S is a 2D map of ``unnormalized'', v velocity, and I integrated intensity map -column density-), then the structure function of the centroids is dominated by the structure function of velocity. We show that it is possible to extract the velocity statistics using centroids for subsonic and mildly supersonic turbulence (e.g. Mach numbers ~2.5). While, towards higher Mach numbers other effects could affect significantly the statistics of centroids.

  1. Statistics of Velocity from Spectral Data Modified Velocity Centroids

    CERN Document Server

    Lazarian, A

    2003-01-01

    We address the problem of studying interstellar (ISM) turbulence using spectral line data. We construct a measure that we term modified velocity centroids (MVCs) and derive an analytical solution that relates the 2D spectra of the modified centroids with the underlying 3D velocity spectrum. We test our results using synthetic maps constructed with data obtained through simulations of compressible MHD turbulence. We prove that the MVCs are able to restore the underlying spectrum of turbulent velocity. We show that the modified velocity centroids (MVCs) are complementary to the the Velocity Channel Analysis (VCA) technique that we introduced earlier. Employed together they make determining of the velocity spectral index more reliable. At the same time we show that MVCs allow to determine velocity spectra when the underlying statistics is not a power law and/or the turbulence is subsonic.

  2. Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Barkou, Stig Eigil; Broeng, Jes; Bjarklev, Anders Overgaard

    1999-01-01

    Photonic bandgap fibers are describes using a new Kagomé cladding structure. These fibers may potentially guide light in low-index regions. Such fibers offer new dispersion properties, and large design flexibility.......Photonic bandgap fibers are describes using a new Kagomé cladding structure. These fibers may potentially guide light in low-index regions. Such fibers offer new dispersion properties, and large design flexibility....

  3. Nanostructured conductive polymeric materials

    Science.gov (United States)

    Al-Saleh, Mohammed H.

    Conductive polymer composites (CPCs) are a suitable alternative to metals in many applications due to their light-weight, corrosion resistance, low cost, ease of processing and design flexibility. CPCs have been formulated using different types of conductive fillers. In this PhD thesis, the focus is on CPCs for electrostatic discharge (ESD) protection and electromagnetic interference (EMI) attenuation. Despite the versatility of conductive fillers, carbon black (CB) has been the dominant filler to make CPCs for ESD protection applications because CB/polymer composites have a cost advantage over all other CPCs. For EMI shielding, stainless steel fibres and metal coated fibers are the preferred fillers, however CPCs made of those fibers are not the dominant EMI shielding materials. Metal coated and polymer plated polymers are the most widely used EMI shielding options. The limited use of CPCs in the EMI shielding market is because the high filler loading required to formulate a composite with an adequate level of shielding remarkably increases the composite price. In order to increase the competitiveness of CPCs, percolation threshold should be minimized as much as possible and composites with high EMI shielding capabilities at low filler loading should be formulated because all conductive fillers are expensive compared to polymers. In this thesis, two different methodologies to reduce percolation threshold in CPCs have been successfully developed and a CPC with exceptional EMI shielding capability has been formulated using copper nanowires as conductive filler. The first percolation threshold reduction technique is based on the selective localization of CB at the interface of immiscible polymer blend. The technique requires adding a copolymer that prefers the blend's interface and for which CB nanoparticles has the highest affinity. The second method is based on producing a CPC powder and then using this powder as a conductive filler to produce composite by dry

  4. Conduction apraxia.

    Science.gov (United States)

    Ochipa, C; Rothi, L J; Heilman, K M

    1994-01-01

    A left hemisphere damaged patient with ideomotor apraxia is described, whose performance on pantomime to verbal command was superior to pantomime imitation. His reception of these same gestures (gesture naming) was spared. This syndrome has been named conduction apraxia. To account for this selective impaired performance on gesture imitation, a separation of the representations for gesture production and reception is proposed and a non-lexical gesture processing route for gesture imitation is suggested. Images PMID:7931387

  5. Conduction apraxia.

    OpenAIRE

    Ochipa, C; Rothi, L J; Heilman, K M

    1994-01-01

    A left hemisphere damaged patient with ideomotor apraxia is described, whose performance on pantomime to verbal command was superior to pantomime imitation. His reception of these same gestures (gesture naming) was spared. This syndrome has been named conduction apraxia. To account for this selective impaired performance on gesture imitation, a separation of the representations for gesture production and reception is proposed and a non-lexical gesture processing route for gesture imitation is...

  6. 双侧正中神经、尺神经多节段运动神经传导各参数正常值的建立%Establishment of normative value of multiple segments motor nerve conduction velocity of bilateral median nerve and ulnar nerve

    Institute of Scientific and Technical Information of China (English)

    张朔; 郑菊阳

    2009-01-01

    目的:建立双侧正中神经、尺神经多节段运动神经传导速度(MCV)、潜伏期(LAT)和波幅(AMP)的正常值.方法:200例健康志愿者,男100例,女100例,分别按年龄分成5组,正中神经记录点在拇短展肌,刺激点分别为掌点、腕点、肘点、腋点、Erb点;尺神经记录点在小指展肌,刺激点分别为腕点、肘下点、肘上点、腋点、Erb点,记录各段MCV、LAT、AMP值.结果:正中神经、尺神经多节段MCV、LAT、AMP与性别、侧别无相关性;年龄与正中神经各段MCV、LAT、AMP及尺神经AMP有关.结论:双侧正中神经、尺神经多节段运动神经传导的准确检测对临床疾病诊断有重要价值.%Objective: To establish normative value of multiple segments motor nerve conduction of bilateral median nerve and ulnar nerve, including motor nerve conduction velocity (MCV)、latency (LAT)and amplitude (AMP). Method: Two hundred normal volunteers were divided into 5 groups according to different ages. Median nerve was examined at multiple points: palm, wrist, elbow, axilla and Erb's. Ulnar nerve was examined at multiple points: wrist, below elbow, above elbow, axilla and Erb's. The values of segmental MCV, LAT and AMP were recorded. Result: Gender and sidedness had no effect on MCV, LAT and AMP of median nerve and ulnar nerve. However, age had significant effects on MCV, LAT and AMP of median nerve and AMP of ulnar nerve. Conclusion: The examination of multiple segments motor nerve conduction of bilateral median nerve and ulnar nerve possess important value in diagnosis.

  7. Indentation of aluminium foam at low velocity

    Directory of Open Access Journals (Sweden)

    Shi Xiaopeng

    2015-01-01

    Full Text Available The indentation behaviour of aluminium foams at low velocity (10 m/s ∼ 30 m/s was investigated both in experiments and numerical simulation in this paper. A flat-ended indenter was used and the force-displacement history was recorded. The Split Hopkinson Pressure bar was used to obtain the indentation velocity and forces in the dynamic experiments. Because of the low strength of the aluminium foam, PMMA bar was used, and the experimental data were corrected using Bacon's method. The energy absorption characteristics varying with impact velocity were then obtained. It was found that the energy absorption ability of aluminium foam gradually increases in the quasi-static regime and shows a significant increase at ∼10 m/s velocity. Numerical simulation was also conducted to investigate this process. A 3D Voronoi model was used and models with different relative densities were investigated as well as those with different failure strain. The indentation energy increases with both the relative density and failure strain. The analysis of the FE model implies that the significant change in energy absorption ability of aluminium foam in indentation at ∼10 m/s velocity may be caused by plastic wave effect.

  8. Imaging Fractures Through Relative Velocity Change Using Ambient Seismic Noise And Distributed Acoustic Sensing (DAS): A SUBTER Pilot Study At Blue Canyon Dome, Socorro NM

    Science.gov (United States)

    James, S. R.; Knox, H. A.; Ajo Franklin, J. B.; Johnson, T. C.; Morris, J.; Grubelich, M. C.; King, D. K.

    2016-12-01

    Knowledge of fracture systems, including locations, morphology, and evolution, is critical for groundwater management, contaminant transport, and energy applications such as reservoir development (i.e. tight shale and geothermal) and reservoir management (i.e. carbon sequestration and wastewater injection). It has long been understood that the presence of fractures reduces bulk seismic velocity, with waves traveling perpendicular to fracture planes experiencing the strongest velocity reduction. We present results from seismic interferometry using ambient seismic noise to detect velocity changes following fracture emplacement from two energetic stimulations. Distributed Acoustic Sensing (DAS) using fiber optic cables was used to record seismic arrivals at high spatial resolution ( 3 ft). Cables were grouted in the annulus of four cased monitoring boreholes surrounding the stimulation borehole at a radius of 4 feet. Ambient noise was recorded before and after each stimulation for 12-hour time periods. We used the Python package MSNoise to compute cross-correlations of all near-horizontal (less than 60°) channel pairs between boreholes and calculated the velocity change of each time period relative to initial conditions prior to stimulation. Results show an average velocity decrease of approximately 6% following the first fracturing event. Variations between channel pairs suggest some are more strongly affected than others, which is supported by evaluation of other geophysical data. These results show promise for locating fractures based on spatial variation in velocity changes. Unsurprisingly, results following the second stimulation are generally more scattered. Some velocities are further reduced compared to those after the first stimulation while others show a relative velocity increase. These results are roughly consistent with time-lapse seismic measurements conducted using active sources and classical sensors (e.g. hydrophones). Sandia National Laboratories is

  9. Minimal information in velocity space

    CERN Document Server

    Evrard, Guillaume

    1995-01-01

    Jaynes' transformation group principle is used to derive the objective prior for the velocity of a non-zero rest-mass particle. In the case of classical mechanics, invariance under the classical law of addition of velocities, leads to an improper constant prior over the unbounded velocity space of classical mechanics. The application of the relativistic law of addition of velocities leads to a less simple prior. It can however be rewritten as a uniform volumetric distribution if the relativistic velocity space is given a non-trivial metric.

  10. Magneto-carbonization method for production of carbon fiber, and high performance carbon fibers made thereby

    Energy Technology Data Exchange (ETDEWEB)

    Naskar, Amit K.; Ozcan, Soydan; Eberle, Claude C.; Abdallah, Mohamed Gabr; Mackiewicz, Ludtka Gail; Ludtka, Gerard Michael; Paulauskas, Felix Leonard; Rivard, John Daniel Kennedy

    2017-08-08

    Method for the preparation of carbon fiber from fiber precursor, wherein the fiber precursor is subjected to a magnetic field of at least 3 Tesla during a carbonization process. The carbonization process is generally conducted at a temperature of at least 400.degree. C. and less than 2200.degree. C., wherein, in particular embodiments, the carbonization process includes a low temperature carbonization step conducted at a temperature of at least or above 400.degree. C. or 500.degree. C. and less than or up to 1000.degree. C., 1100.degree. C., or 1200.degree. C., followed by a high temperature carbonization step conducted at a temperature of at least or above 1200.degree. C. In particular embodiments, particularly in the case of a polyacrylonitrile (PAN) fiber precursor, the resulting carbon fiber may possess a minimum tensile strength of at least 600 ksi, a tensile modulus of at least 30 Msi, and an ultimate elongation of at least 1.5%.

  11. Fluid Structure Interaction Effects on Composites Under Low Velocity Impact

    Science.gov (United States)

    2012-06-01

    Interaction, FSI, low velocity impact, carbon fiber reinforced polymers, CFRP, carbon nanotubes, CNT, vacuum assisted resin transfer molding, VARTM . 16...Ethyl Ketone Peroxide MWCNT Multi-Walled Carbon Nanotube VARTM Vacuum-Assisted Resin Transfer Molding xiv THIS PAGE INTENTIONALLY LEFT BLANK...samples used in this research is known as vacuum assisted resin transfer molding ( VARTM ). VARTM is a very common method used in low pressure composite

  12. Investigation of a fiber optic surface plasmon spectroscopy in conjunction with conductivity as an in situ method for simultaneously monitoring changes in dissolved organic carbon and salinity in coastal waters.

    Science.gov (United States)

    Kim, Yoon-Chang; Cramer, Jeffrey A; Booksh, Karl S

    2011-10-21

    A combination surface plasmon resonance (SPR) and conductivity sensor array was developed and implemented to demonstrate the ability to differentiate among changes in dissolved organic carbon (DOC) and salinity in coastal water. The array is capable of achieving sufficient spatial and temporal data density to better understand the cycling and fate of terrestrial DOC in coastal areas. DOC is the second largest source of bioreactive carbon in the environment and plays a key role in mediating microbial activity and generation of atmospheric CO(2). In the coastal areas, the salinity is also an important property in many applications, such as leak detection for landfill liners, saltwater intrusion to drinking water, marine environment monitoring, and seasonal climate prediction. Conductivity sensors are the industry standard for determining salinity in ocean systems. However, both conductivity and refractive index sensors, such as SPR spectroscopy based sensors, respond to salinity and DOC levels. To demonstrate the capability of the SPR sensor and a conductivity sensor to collect complimentary data useful in discrimination of salinity and DOC in coastal zone water, conductivity, SPR, and temperature data were collected during passage from the Juan de Fuca ridge area returning to the University of Washington docks.

  13. Conductivity Probe

    Science.gov (United States)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  14. Visual control of walking velocity.

    Science.gov (United States)

    François, Matthieu; Morice, Antoine H P; Bootsma, Reinoud J; Montagne, Gilles

    2011-06-01

    Even if optical correlates of self-motion velocity have already been identified, their contribution to the control of displacement velocity remains to be established. In this study, we used a virtual reality set-up coupled to a treadmill to test the role of both Global Optic Flow Rate (GOFR) and Edge Rate (ER) in the regulation of walking velocity. Participants were required to walk at a constant velocity, corresponding to their preferred walking velocity, while eye height and texture density were manipulated. This manipulation perturbed the natural relationship between the actual walking velocity and its optical specification by GOFR and ER, respectively. Results revealed that both these sources of information are indeed used by participants to control walking speed, as demonstrated by a slowing down of actual walking velocity when the optical specification of velocity by either GOFR or ER gives rise to an overestimation of actual velocity, and vice versa. Gait analyses showed that these walking velocity adjustments result from simultaneous adaptations in both step length and step duration. The role of visual information in the control of self-motion velocity is discussed in relation with other factors.

  15. Static and dynamic behavior of carbon fiber reinforced aluminum (CARALL) laminates

    Science.gov (United States)

    Dhaliwal, Gurpinder Singh

    /w aluminum & CFRP layers. The threshold impact energy, energy at which perforation failure was induced in all metallic and fiber reinforced layers for these laminates was found to be around 31J. Finite element analysis utilizing LS-DYNA software was performed to predict load-displacement history, delamination area, absorbed energy, damage morphologies on impacted and non-impacted sides and tensile failures of CFRP layers for an impact event at three different energy levels. Delamination at the aluminum and carbon fiber layers interfaces was modeled by using with traction separation law and damage criterion proposed by Benzeggagh-Kenane was used for interface damage evolution. Predicted impact behavior results match well with experimental results. Length-wise compression after impact static tests was conducted for impacted and non-impacted samples to determine the residual strength of these fiber metal laminates after the impact event. By comparing FMLs systems cured with and without using polyester surfacing veil cloth layers in terms of residual strength at the same impact energy, it is found that the FMLs having cloth layers provides higher residual strength than the regular FMLs cured without cloth layers composite system due to the higher interlaminar strength of the composite system. These results provide a clear understanding of the failure modes of these FMLs under different loading conditions and how they influence the overall composite behavior. A unique contribution of the thesis work is the investigation of the effect of resin rich polyester veil cloth on flexural, tensile, low-velocity impact & compression after impact characteristics of these carbon fiber reinforced aluminum laminates. These results can be used in designing lightweight automotive and aerospace components.

  16. Stress-Release Seismic Source for Seismic Velocity Measurement in Mines

    Science.gov (United States)

    Swanson, P. L.; Clark, C.; Richardson, J.; Martin, L.; Zahl, E.; Etter, A.

    2014-12-01

    Accurate seismic event locations are needed to delineate roles of mine geometry, stress and geologic structures in developing rockburst conditions. Accurate absolute locations are challenging in mine environments with rapid changes in seismic velocity due to sharp contrasts between individual layers and large time-dependent velocity gradients attending excavations. Periodic use of controlled seismic sources can help constrain the velocity in this continually evolving propagation medium comprising the miners' workplace. With a view to constructing realistic velocity models in environments in which use of explosives is problematic, a seismic source was developed subject to the following design constraints: (i) suitable for use in highly disturbed zones surrounding mine openings, (ii) able to produce usable signals over km-scale distances in the frequency range of typical coal mine seismic events (~10-100 Hz), (iii) repeatable, (iv) portable, (v) non-disruptive to mining operations, and (vi) safe for use in potentially explosive gaseous environments. Designs of the compressed load column seismic source (CLCSS), which generates a stress, or load, drop normal to the surface of mine openings, and the fiber-optic based source-initiation timer are presented. Tests were conducted in a coal mine at a depth of 500 m (1700 ft) and signals were recorded on the surface with a 72-ch (14 Hz) exploration seismograph for load drops of 150-470 kN (16-48 tons). Signal-to-noise ratios of unfiltered signals ranged from ~200 immediately above the source (500 m (1700 ft)) to ~8 at the farthest extent of the array (slant distance of ~800 m (2600 ft)), suggesting the potential for use over longer range. Results are compared with signals produced by weight drop and sledge hammer sources, indicating the superior waveform quality for first-arrival measurements with the CLCSS seismic source.

  17. Methods of Measurement of High Air Velocities by the Hot-wire Method

    Science.gov (United States)

    Weske, John R.

    1943-01-01

    Investigations of strengths of hot wires at high velocities were conducted with platinum, nickel, and tungsten at approximately 200 Degrees Celcius hot-wire temperature. The results appear to disqualify platinum for velocities approaching the sonic range; whereas nickel withstands sound velocity, and tungsten may be used for supersonic velocities under standard atmospheric conditions. Hot wires must be supported by rigid prolongs at high velocities to avoid wire breakage. Resting current measurements for constant temperature show agreement with King's relation.

  18. Rate dependent response and failure of a ductile epoxy and carbon fiber reinforced epoxy composite

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Eric N [Los Alamos National Laboratory; Rae, Philip J [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Stahl, David B [Los Alamos National Laboratory

    2010-01-01

    An extensive characterization suite has been performed on the response and failure of a ductile epoxy 55A and uniaxial carbon fiber reinforced epoxy composite of IM7 fibers in 55A resin from the quasistatic to shock regime. The quasistatic and intermediate strain rate response, including elastic modulus, yield and failure have are characterized by quasistatic, SHPB, and DMA measurements as a function of fiber orientation and temperature. The high strain rate shock effect of fiber orientation in the composite and response of the pure resin are presented for plate impact experiments. It has previously been shown that at lower impact velocities the shock velocity is strongly dependent on fiber orientation but at higher impact velocity the in-plane and through thickness Hugoniots converge. The current results are compared with previous studies of the shock response of carbon fiber composites with more conventional brittle epoxy matrices. The spall response of the composite is measured and compared with quasistatic fracture toughness measurements.

  19. Increased thermal conductivity monolithic zeolite structures

    Science.gov (United States)

    Klett, James; Klett, Lynn; Kaufman, Jonathan

    2008-11-25

    A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

  20. Impulse propagation in a conducting medium with arbitrary thermal conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Myasnikov, S.P.

    1977-07-01

    An examination is made of impulse propagation in a conducting medium that accounts for its thermal conductivity. Such a medium, even with an infinitely large electric conductivity, will have a weak dispersion. Following dispersion through a sufficiently large time interval, out of the entire set of planar waves comprising a wave packet, only the low-frequency components were shown to remain (these are the components that are propagated at a velocity of c/sub s/) along with the high-frequency components that are propagated at the speed of c/sub T/. Consequently, the initial derangement is converted into two separate waves of a bell-shaped form that run to various sides at a phase velocity equal to the adiabatic speed of sound c/sub s/. 6 references.

  1. Drawing Nylon 6,6 Fibers in High Pressure CO2

    Science.gov (United States)

    2005-12-07

    studies have been performed on various fibers using supercritical carbon dioxide treatments. In these studies, Nylon6,6, PBO ( Zylon ) and...Supercritical carbon dioxide, High Performance Fibers , Nylon6,6, PBO ( Zylon ), Polyester Fibers 15. NUMBER OF PAGES...conducted on poly-p-phenylenebenzobisoxazole (PBO) currently manufactured by Toyobo under the commercial name Zylon . These fibers were selected because of

  2. Conducted Vasoreactivity

    DEFF Research Database (Denmark)

    Postnov, D. E.; Neganova, A Y; Sosnovtseva, Olga

    2015-01-01

    , the underlying mechanisms are debated. Here, we focus on dynamical aspects of the problem hypothesizing the existence of a bistability-powered mechanism for regenerative pulse transmission along the endothelium. Bistability implies that the cell can have two different stable resting potentials and can switch......Conducted vasodilation is part of the physiological response to increasing metabolic demand of the tissue. Similar responses can be elicited by focal electrical or chemical stimulation. Some evidence suggests an endothelial pathway for nondecremental transmission of hyperpolarizing pulses. However...... a theoretical analysis as well as numerical simulations of both single- and multiunit bistable systems mimicking endothelial cells to investigate the self-consistence and stability of the proposed mechanism. We find that the individual cell may switch readily between two stable potentials. An array of coupled...

  3. Characterizing Cellulosic Fibers from Ulex europaeus

    Directory of Open Access Journals (Sweden)

    Richard Celis

    2014-10-01

    Full Text Available Information on the morphological and physical properties of biofibers is necessary to support the mechanical understanding of the biological design of plants, as well as for the development of new technology that adds value to non-traditional bioresources, such as those based on Ulex europaeus fibers. Ulex europaeus fibers were extracted through a chemical pulping process at 170 °C and with 40 g/L NaOH. The dimensions of the fibers produced were 0.97 ± 0.1 mm in length and 13 ± 2 μm in diameter. Pressed fiber paper sheets were made to evaluate their mechanical properties. Burst and tear indices of 1.2 mN/kg and 8.6 Nm2/kg, respectively, were recorded. The values obtained did not compare well to fiber paper sheets from Pinus radiata, presumably due to the significant amount of non-structural elements of wood present in the samples and the lower length of Ulex europaeus fibers, which resulted in lower tensile strength. Additionally, nanoindentation tests were conducted to assess the hardness and elastic modulus of the fibers, obtaining average values of 0.84 GPa and 9.23 GPa for the stem, respectively. These values were significantly lower than those of industrial biofiber, perhaps due to the lower morphogenic maturity of Ulex europaeus fibers compared to other traditional sources of fiber.

  4. Development of an optimal velocity selection method with velocity obstacle

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Geuk; Oh, Jun Ho [KAIST, Daejeon (Korea, Republic of)

    2015-08-15

    The Velocity obstacle (VO) method is one of the most well-known methods for local path planning, allowing consideration of dynamic obstacles and unexpected obstacles. Typical VO methods separate a velocity map into a collision area and a collision-free area. A robot can avoid collisions by selecting its velocity from within the collision-free area. However, if there are numerous obstacles near a robot, the robot will have very few velocity candidates. In this paper, a method for choosing optimal velocity components using the concept of pass-time and vertical clearance is proposed for the efficient movement of a robot. The pass-time is the time required for a robot to pass by an obstacle. By generating a latticized available velocity map for a robot, each velocity component can be evaluated using a cost function that considers the pass-time and other aspects. From the output of the cost function, even a velocity component that will cause a collision in the future can be chosen as a final velocity if the pass-time is sufficiently long enough.

  5. Hybrid use of steel and carbon-fiber reinforced concrete for monitoring of crack behavior

    OpenAIRE

    Ding, Yining; Han, Z; Zhang, Y; Azevedo, Cecília Maria

    2012-01-01

    In order to study the damage after concrete cracking, the influence of the combined use of steel fiber and carbon fiber on the conductivity and crack resistance of concrete beam under flexural loading were investigated. Carbon fiber and steel fiber were added as diphasic conductive materials to produce the electric conductive and ductile concrete. This paper reports the experimental and analytical work associated with establishing the crack width in relation to the fractional c...

  6. Velocity dependant splash behaviour

    Science.gov (United States)

    Hamlett, C. A. E.; Shirtcliffe, N. J.; McHale, G.; Ahn, S.; Doerr, S. H.; Bryant, R.; Newton, M. I.

    2012-04-01

    Extreme soil water repellency can occur in nature via condensation of volatile organic compounds released during wildfires and can lead to increased erosion rate. Such extreme water repellent soil can be classified as superhydrophobic and shares similar chemical and topographical features to specifically designed superhydrophobic surfaces. Previous studies using high speed videography to investigate single droplet impact behaviour on artificial superhydrophobic have revealed three distinct modes of splash behaviour (rebound, pinned and fragmentation) which are dependent on the impact velocity of the droplet. In our studies, using high-speed videography, we show that such splash behaviour can be replicated on fixed 'model' water repellent soils (hydrophobic glass beads/particles). We show that the type of splash behaviour is dependent on both the size and chemical nature of the fixed particles. The particle shape also influences the splash behaviour as shown by drop impact experiments on fixed sand samples. We have also studied soil samples, as collected from the field, which shows that the type of droplet splash behaviour can lead to enhanced soil particle transport.

  7. Photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Hansen, K P; Nielsen, M D;

    2003-01-01

    Photonic crystal fibers having a complex microstructure in the transverse plane constitute a new and promising class of optical fibers. Such fibers can either guide light through total internal reflection or the photonic bandgap effect, In this paper, we review the different types and applications...... of photonic crystal fibers with particular emphasis on recent advances in the field....

  8. Photonic crystal fibers -

    DEFF Research Database (Denmark)

    Libori, Stig E. Barkou

    2002-01-01

    During this ph.d. work, attention has been focused on understanding and analyzing the modal behavior of micro-structured fibers. Micro-structured fibers are fibers with a complex dielectric toplogy, and offer a number of novel possibilities, compared to standard silica based optical fibers. The t...

  9. Photonic Crystal Fiber Attenuator

    Institute of Scientific and Technical Information of China (English)

    Joo; Beom; Eom; Hokyung; Kim; Jinchae; Kim; Un-Chul; Paek; Byeong; Ha; Lee

    2003-01-01

    We propose a novel fiber attenuator based on photonic crystal fibers. The difference in the modal field diameters of a conventional single mode fiber and a photonic crystal fiber was used. A variable optical attenuator was also achieved by applying macro-bending on the PCF part of the proposed attenuator

  10. Cognitive regulation of saccadic velocity by reward prospect.

    Science.gov (United States)

    Chen, Lewis L; Hung, Leroy Y; Quinet, Julie; Kosek, Kevin

    2013-08-01

    It is known that expectation of reward speeds up saccades. Past studies have also shown the presence of a saccadic velocity bias in the orbit, resulting from a biomechanical regulation over varying eccentricities. Nevertheless, whether and how reward expectation interacts with the biomechanical regulation of saccadic velocities over varying eccentricities remains unknown. We addressed this question by conducting a visually guided double-step saccade task. The role of reward expectation was tested in monkeys performing two consecutive horizontal saccades, one associated with reward prospect and the other not. To adequately assess saccadic velocity and avoid adaptation, we systematically varied initial eye positions, saccadic directions and amplitudes. Our results confirmed the existence of a velocity bias in the orbit, i.e., saccadic peak velocity decreased linearly as the initial eye position deviated in the direction of the saccade. The slope of this bias increased as saccadic amplitudes increased. Nevertheless, reward prospect facilitated velocity to a greater extent for saccades away from than for saccades toward the orbital centre, rendering an overall reduction in the velocity bias. The rate (slope) and magnitude (intercept) of reward modulation over this velocity bias were linearly correlated with amplitudes, similar to the amplitude-modulated velocity bias without reward prospect, which presumably resulted from a biomechanical regulation. Small-amplitude (≤ 5°) saccades received little modulation. These findings together suggest that reward expectation modulated saccadic velocity not as an additive signal but as a facilitating mechanism that interacted with the biomechanical regulation.

  11. Experimental Investigations on Thermal Conductivity of Fenugreek and Banana Composites

    Science.gov (United States)

    Pujari, Satish; Venkatesh, Talari; Seeli, Hepsiba

    2017-06-01

    The use of composite materials in manufacturing has significantly increased in the past decade. Research is being done to identify natural fibers that can be used as composites. Several natural fibers are already being used in the industry as composites. The appealing advantages of using natural fibers are reflected in lower density when compared to synthetic fibers and also in saving costs. This research paper highlights the experiment that analyses the use of biodegradable fenugreek composite as natural fiber and concludes that fenugreek natural fibers are an excellent substitute to the synthetic fibers in terms of reinforcement properties for the polymers. These fenugreek fibers are naturally sourced, renewable, cost effective and bio-friendly. In thermal energy storage systems as well as in air conditioning systems, thermal insulators are predominantly used to enhance the storage properties. An experiment was created to investigate the thermal properties of fenugreek banana composites for different fiber concentrations. The experimental results showed that the thermal conductivity of the composites decrease with an increase in the fiber content. The experimental results were compared with the theoretical models to describe the variation of thermal conductivity with the volume fraction of the fiber. Good agreement between theoretical and experimental results was observed.

  12. [Conduct disorders].

    Science.gov (United States)

    Stadler, Christina

    2014-05-01

    The diagnosis conduct disorder (CD) is characterized by aggressive (e.g., physical aggression) as well as nonaggressive symptoms (e.g., violation of rules, truancy). Conclusions regarding the course and prognosis, or recommendations for effective interventions, seem not to be equally valid for the whole patient group. DSM-IV-TR included subtyping age-of-onset as a prognostic criterion, even though the evidence base for subtyping from age of onset was rather sparse. The relevant literature on CD has grown substantially since the publication of DSM-IV-TR in 1994. For the new DSM-5 edition, some important issues were discussed, for example, consideration of personality traits, female-specific or dimensional criteria, and adding a childhood-limited subtype (Moffitt et al., 2008). Nevertheless, the diagnostic protocol for CD was not changed in the most parts in the new edition of the DSM-5; the addition of a CD specifier with limited emotions is the most relevant change. On the basis of the existing evidence base, this review discusses whether the modifications in DSM-5 are helpful for fulfilling the requirements of a reliable and valid psychiatric classification.

  13. Carbon nanotube reinforced polyacrylonitrile and poly(etherketone) fibers

    Science.gov (United States)

    Jain, Rahul

    The graphitic nature, continuous structure, and high mechanical properties of carbon nanotubes (CNTs) make them good candidate for reinforcing polymer fiber. The different types of CNTs including single-wall carbon nanotubes (SWNTs), few-wall carbon nanotubes (FWNTs), and multi-wall carbon nanotubes (MWNTs), and carbon nanofibers (CNFs) differ in terms of their diameter and number of graphitic walls. The desire has been to increase the concentration of CNTs as much as possible to make next generation multi-functional materials. The work in this thesis is mainly focused on MWNT and CNF reinforced polyacrylonitrile (PAN) composite fibers, and SWNT, FWNT, and MWNT reinforced poly(etherketone) (PEK) composite fibers. To the best of our knowledge, this is the first study to report the spinning of 20% MWNT or 30% CNF reinforced polymer fiber spun using conventional fiber spinning. Also, this is the first study to report the PEK/CNT composite fibers. The fibers were characterized for their thermal, tensile, mechanical, and dynamic mechanical properties. The fiber structure and morphology was studied using WAXD and SEM. The effect of two-stage heat drawing, sonication time for CNF dispersion, fiber drying temperature, and molecular weight of PAN was also studied. Other challenges associated with processing high concentrations of solutions for making composite fibers have been identified and reported. The effect of CNT diameter and concentration on fiber spinnability and electrical conductivity of composite fiber have also been studied. This work suggests that CNT diameter controls the maximum possible concentration of CNTs in a composite fiber. The results show that by properly choosing the type of CNT, length of CNTs, dispersion of CNTs, fiber spinning method, fiber draw ratio, and type of polymer, one can get electrically conducting fibers with wide range of conductivities for different applications. The PEK based control and composite fibers possess high thermal

  14. A theoretical model of turbulent fiber suspension and its application to the channel flow

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A theoretical model of turbulent fiber suspension is developed by deriving the equations of Reynolds averaged Navier-Stokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of fibers.In order to close the above equations,the equation of probability distribution function for mean fiber orientation is also derived.The theoretical model is applied to the turbulent channel flow and the corresponding equations are solved numerically.The numerical results are verified by comparisons with the experimental ones.The effects of Reynolds number,fiber concentration and fiber aspect-ratio on the velocity profile,turbulent kinetic energy and turbulent dissipation rate are analyzed.Based on the numerical data,the expression for the velocity profile in the turbulent fiber suspension channel flow,which includes the effect of Reynolds number,fiber concentration and aspect-ratio,is proposed.

  15. High velocity impact experiment (HVIE)

    Energy Technology Data Exchange (ETDEWEB)

    Toor, A.; Donich, T.; Carter, P.

    1998-02-01

    The HVIE space project was conceived as a way to measure the absolute EOS for approximately 10 materials at pressures up to {approximately}30 Mb with order-of-magnitude higher accuracy than obtainable in any comparable experiment conducted on earth. The experiment configuration is such that each of the 10 materials interacts with all of the others thereby producing one-hundred independent, simultaneous EOS experiments The materials will be selected to provide critical information to weapons designers, National Ignition Facility target designers and planetary and geophysical scientists. In addition, HVIE will provide important scientific information to other communities, including the Ballistic Missile Defense Organization and the lethality and vulnerability community. The basic HVIE concept is to place two probes in counter rotating, highly elliptical orbits and collide them at high velocity (20 km/s) at 100 km altitude above the earth. The low altitude of the experiment will provide quick debris strip-out of orbit due to atmospheric drag. The preliminary conceptual evaluation of the HVIE has found no show stoppers. The design has been very easy to keep within the lift capabilities of commonly available rides to low earth orbit including the space shuttle. The cost of approximately 69 million dollars for 100 EOS experiment that will yield the much needed high accuracy, absolute measurement data is a bargain!

  16. Evidence for ACTN3 as a Speed Gene in Isolated Human Muscle Fibers.

    Directory of Open Access Journals (Sweden)

    Siacia Broos

    Full Text Available To examine the effect of α-actinin-3 deficiency due to homozygosity for the ACTN3 577X-allele on contractile and morphological properties of fast muscle fibers in non-athletic young men.A biopsy was taken from the vastus lateralis of 4 RR and 4 XX individuals to test for differences in morphologic and contractile properties of single muscle fibers. The cross-sectional area of the fiber and muscle fiber composition was determined using standard immunohistochemistry analyses. Skinned single muscle fibers were subjected to active tests to determine peak normalized force (P0, maximal unloading velocity (V0 and peak power. A passive stretch test was performed to calculate Young's Modulus and hysteresis to assess fiber visco-elasticity.No differences were found in muscle fiber composition. The cross-sectional area of type IIa and IIx fibers was larger in RR compared to XX individuals (P<0.001. P0 was similar in both groups over all fiber types. A higher V0 was observed in type IIa fibers of RR genotypes (P<0.001 but not in type I fibers. The visco-elasticity as determined by Young's Modulus and hysteresis was unaffected by fiber type or genotype.The greater V0 and the larger fast fiber CSA in RR compared to XX genotypes likely contribute to enhanced whole muscle performance during high velocity contractions.

  17. Examples of Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Hansen, Peter M.; Pedersen, Mads M.; Hansen, Kristoffer L.

    2011-01-01

    To measure blood flow velocity in vessels with conventional ultrasound, the velocity is estimated along the direction of the emitted ultrasound wave. It is therefore impossible to obtain accurate information on blood flow velocity and direction, when the angle between blood flow and ultrasound wa...... with a 90° angle on the vessel. Moreover secondary flow in the abdominal aorta is illustrated by scanning on the transversal axis....

  18. An inexpensive high-temperature optical fiber thermometer

    Science.gov (United States)

    Moore, Travis J.; Jones, Matthew R.; Tree, Dale R.; Allred, David D.

    2017-01-01

    An optical fiber thermometer consists of an optical fiber whose tip is coated with a highly conductive, opaque material. When heated, this sensing tip becomes an isothermal cavity that emits like a blackbody. This emission is used to predict the sensing tip temperature. In this work, analytical and experimental research has been conducted to further advance the development of optical fiber thermometry. An inexpensive optical fiber thermometer is developed by applying a thin coating of a high-temperature cement onto the tip of a silica optical fiber. An FTIR spectrometer is used to detect the spectral radiance exiting the fiber. A rigorous mathematical model of the irradiation incident on the detection system is developed. The optical fiber thermometer is calibrated using a blackbody radiator and inverse methods are used to predict the sensing tip temperature when exposed to various heat sources.

  19. High power fiber lasers

    Institute of Scientific and Technical Information of China (English)

    LOU Qi-hong; ZHOU Jun

    2007-01-01

    In this review article, the development of the double cladding optical fiber for high power fiber lasers is reviewed. The main technology for high power fiber lasers, including laser diode beam shaping, fiber laser pumping techniques, and amplification systems, are discussed in de-tail. 1050 W CW output and 133 W pulsed output are ob-tained in Shanghai Institute of Optics and Fine Mechanics, China. Finally, the applications of fiber lasers in industry are also reviewed.

  20. Prediction of Final Velocity of Aramid Fabric-Resin Composite Laminates Subjected to Ballistic Impact

    Institute of Scientific and Technical Information of China (English)

    熊杰; 萧庆亮; 刘冠峰; 顾伯洪; 王善元

    2003-01-01

    The strain rate effects of aramid fiber material,quasi-static and ballistic impact perforation of composite laminates made of aramid fabric and phenolic resin/PVB are investigated respectively by means of MTS, split Hopkinson tension bars and ballistic impact apparatus. The tensile impact experiments on aramid fiber material are performed in strain rate range from 0.01/ s to 1 000/ s. Experinental results show that the mechanical properties of aramid fiber material are insensitive to strain rate in the range from 0. 01/s to 1 000/s. An energy model to predict final velocity of composite laminates subjected to ballistic impact is proposed on the basis of experimental data of quasi-static perforation through the targets. The predicted final velocities show good agreement with the experimental final velocity.

  1. Design of the fiber optic support system and fiber bundle accelerated life test for VIRUS

    Science.gov (United States)

    Soukup, Ian M.; Beno, Joseph H.; Hayes, Richard J.; Heisler, James T.; Mock, Jason R.; Mollison, Nicholas T.; Good, John M.; Hill, Gary J.; Vattiat, Brian L.; Murphy, Jeremy D.; Anderson, Seth C.; Bauer, Svend M.; Kelz, Andreas; Roth, Martin M.; Fahrenthold, Eric P.

    2010-07-01

    The quantity and length of optical fibers required for the Hobby-Eberly Telescope* Dark Energy eXperiment (HETDEX) create unique fiber handling challenges. For HETDEX‡, at least 33,600 fibers will transmit light from the focal surface of the telescope to an array of spectrographs making up the Visible Integral-Field Replicable Unit Spectrograph (VIRUS). Up to 96 Integral Field Unit (IFU) bundles, each containing 448 fibers, hang suspended from the telescope's moving tracker located more than 15 meters above the VIRUS instruments. A specialized mechanical system is being developed to support fiber optic assemblies onboard the telescope. The discrete behavior of 448 fibers within a conduit is also of primary concern. A life cycle test must be conducted to study fiber behavior and measure Focal Ratio Degradation (FRD) as a function of time. This paper focuses on the technical requirements and design of the HETDEX fiber optic support system, the electro-mechanical test apparatus for accelerated life testing of optical fiber assemblies. Results generated from the test will be of great interest to designers of robotic fiber handling systems for major telescopes. There is concern that friction, localized contact, entanglement, and excessive tension will be present within each IFU conduit and contribute to FRD. The test apparatus design utilizes six linear actuators to replicate the movement of the telescope over 65,000 accelerated cycles, simulating five years of actual operation.

  2. Dietary fiber and fiber fraction intakes and colorectal cancer risk in Chinese adults.

    Science.gov (United States)

    Zhong, Xiao; Fang, Yu-Jing; Pan, Zhi-Zhong; Lu, Min-Shan; Zheng, Mei-Chun; Chen, Yu-Ming; Zhang, Cai-Xia

    2014-01-01

    Few studies have been conducted in Chinese adults to investigate the effect of fiber intake on colorectal cancer risk. The present study aimed to examine the associations of dietary fiber and fiber fraction intakes with colorectal cancer risk in Chinese adults. A total of 613 cases with colorectal cancer were consecutively recruited between July 2010 and October 2012 and frequency matched to 613 controls by age (5-yr interval) and gender. Dietary information was collected through a validated food frequency questionnaire by face-to-face interviews. Multivariate logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) after adjustment for potential confounders. Total dietary fiber and fiber fraction intakes were found to be inversely associated with colorectal cancer risk. Compared with the lowest quartile, the adjusted ORs (95% CIs) for the highest quartile were 0.38 (0.27-0.55) for total dietary fiber, 0.45 (0.32-0.64) for vegetable fiber, and 0.41 (0.28-0.58) for fruit fiber, respectively. In addition, no significant association was found between soy fiber intake and colorectal cancer risk. This study showed that a high intake of dietary fiber, particularly derived from vegetables and fruit, was inversely associated with colorectal cancer risk in Chinese adults.

  3. Universal power law for front propagation in all fiber resonators.

    Science.gov (United States)

    Coulibaly, S; Taki, M; Tlidi, M

    2014-01-13

    We consider a bistable system consisting of all fiber cavity driven by an external injected continuous wave. We report on front propagation in a high finesse cavity. We study the asymptotic behavior of the front velocity. We show that the front velocity is affected by the distance from the critical point associated with bistability. We provide a scaling low governing its evolution near the up-switching point of the bistable curve. We show also that the velocity of front propagation obeys a generic power law when the front velocity approaches asymptotically its linear growing value.

  4. Carbon Fiber Reinforced Polymer with Shredded Fibers: Quasi-Isotropic Material Properties and Antenna Performance

    Directory of Open Access Journals (Sweden)

    Gerald Artner

    2017-01-01

    Full Text Available A carbon fiber reinforced polymer (CFRP laminate, with the top layer consisting of shredded fibers, is proposed and manufactured. The shredded fibers are aligned randomly on the surface to achieve a more isotropic conductivity, as is desired in antenna applications. Moreover, fiber shreds can be recycled from carbon fiber composites. Conductivity, permittivity, and permeability are obtained with the Nicolson-Ross-Weir method from material samples measured inside rectangular waveguides in the frequency range of 4 to 6 GHz. The decrease in material anisotropy results in negligible influence on antennas. This is shown by measuring the proposed CFRP as ground plane material for both a narrowband wire monopole antenna for 5.9 GHz and an ultrawideband conical monopole antenna for 1–10 GHz. For comparison, all measurements are repeated with a twill-weave CFRP.

  5. Fluid-Structure Interaction in a Fluid-Filled Composite Structure Subjected to Low Velocity Impact

    Science.gov (United States)

    2016-06-01

    this study of impact force, deflection, and strain were measured in a carbon fiber reinforced polymer (CFRP) composite cylinder subjected to low...Sanchez, J. Lopez-Puente, and D. Varas, “On the influence of filling level in CFRP aircraft fuel tank subjected to high velocity impacts,” Composite ...and back sides. The baffle provided the greatest strain reduction at the high fill levels. 14. SUBJECT TERMS glass fiber composite , fluid structure

  6. Sodium Velocity Maps on Mercury

    Science.gov (United States)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  7. Correlation Function Approach for Estimating Thermal Conductivity in Highly Porous Fibrous Materials

    Science.gov (United States)

    Martinez-Garcia, Jorge; Braginsky, Leonid; Shklover, Valery; Lawson, John W.

    2011-01-01

    Heat transport in highly porous fiber networks is analyzed via two-point correlation functions. Fibers are assumed to be long and thin to allow a large number of crossing points per fiber. The network is characterized by three parameters: the fiber aspect ratio, the porosity and the anisotropy of the structure. We show that the effective thermal conductivity of the system can be estimated from knowledge of the porosity and the correlation lengths of the correlation functions obtained from a fiber structure image. As an application, the effects of the fiber aspect ratio and the network anisotropy on the thermal conductivity is studied.

  8. A fully woven touchpad sensor based on soft capacitor fibers

    CERN Document Server

    Gu, Jian Feng; Skorobogatiy, Maksim

    2011-01-01

    A novel, highly flexible capacitor fiber (with 100 nF m-1 typical capacitance per length) having a multilayer periodic structure of dielectric and conductive polymer composite films is fabricated by drawing technique. The fiber is used to build a woven touchpad sensor. Then, we study the influence of the fiber length, capacitance and volume resistivity on the touch sensing performance. A theoretical ladder network model of a fiber network is developed. A fully woven textile sample incorporating one-dimension array of the capacitor fibers is fabricated. Finally we show that such an array functions as a two-dimensional touch sensor.

  9. THE ROLE OF POROUS MEDIA IN MODELING FLUID FLOW WITHIN HOLLOW FIBER MEMBRANES OF THE TOTAL ARTIFICIAL LUNG.

    Science.gov (United States)

    Khanafer, Khalil; Cook, Keith; Marafie, Alia

    2012-01-01

    A numerical study was conducted to analyze fluid flow within hollow fiber membranes of the artificial lungs. The hollow fiber bundle was approximated using a porous media model. In addition, the transport equations were solved using the finite-element formulation based on the Galerkin method of weighted residuals. Comparisons with previously published work on the basis of special cases were performed and found to be in excellent agreement. A Newtonian viscous fluid model for the blood was used. Different flow models for porous media, such as the Brinkman-extended Darcy model, Darcy's law model, and the generalized flow model, were considered. Results were obtained in terms of streamlines, velocity vectors, and pressure distribution for various Reynolds numbers and Darcy numbers. The results from this investigation showed that the pressure drop across the artificial lung device increased with an increase in the Reynolds number. In addition, the pressure drop was found to increase significantly for small Darcy numbers.

  10. Lamb Wave Assessment of Fiber Volume Fraction in Composites

    Science.gov (United States)

    Seale, Michael D.; Smith, Barry T.; Prosser, W. H.; Zalameda, Joseph N.

    1998-01-01

    Among the various techniques available, ultrasonic Lamb waves offer a convenient method of examining composite materials. Since the Lamb wave velocity depends on the elastic properties of a material, an effective tool exists to evaluate composites by measuring the velocity of these waves. Lamb waves can propagate over long distances and are sensitive to the desired in-plane elastic properties of the material. This paper discusses a study in which Lamb waves were used to examine fiber volume fraction variations of approximately 0.40-0.70 in composites. The Lamb wave measurements were compared to fiber volume fractions obtained from acid digestion tests. Additionally, a model to predict the fiber volume fraction from Lamb wave velocity values was evaluated.

  11. Amplitude-modulated fiber-ring laser

    DEFF Research Database (Denmark)

    Caputo, J. G.; Clausen, Carl A. Balslev; Sørensen, Mads Peter

    2000-01-01

    Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self-starting......Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self......-starting of stable solitonic pulses from small random noise, provided the modulation depth is small. The perturbative analysis leads to a nonlinear coupled return map for the amplitude, phase, and position of the soliton pulses circulating in the fiber-ring laser. We established the validity of this approach...

  12. Amplitude-modulated fiber-ring laser

    DEFF Research Database (Denmark)

    Caputo, J. G.; Clausen, Carl A. Balslev; Sørensen, Mads Peter

    2000-01-01

    Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self-starting......Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self......-starting of stable solitonic pulses from small random noise, provided the modulation depth is small. The perturbative analysis leads to a nonlinear coupled return map for the amplitude, phase, and position of the soliton pulses circulating in the fiber-ring laser. We established the validity of this approach...

  13. Introduction to vector velocity imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Udesen, Jesper; Hansen, Kristoffer Lindskov;

    Current ultrasound scanners can only estimate the velocity along the ultrasound beam and this gives rise to the cos() factor on all velocity estimates. This is a major limitation as most vessels are close to perpendicular to the beam. Also the angle varies as a function of space and time making...

  14. Instantaneous Velocity Using Photogate Timers

    Science.gov (United States)

    Wolbeck, John

    2010-01-01

    Photogate timers are commonly used in physics laboratories to determine the velocity of a passing object. In this application a card attached to a moving object breaks the beam of the photogate timer providing the time for the card to pass. The length L of the passing card can then be divided by this time to yield the average velocity (or speed)…

  15. Kriging Interpolating Cosmic Velocity Field

    CERN Document Server

    Yu, Yu; Jing, Yipeng; Zhang, Pengjie

    2015-01-01

    [abridge] Volume-weighted statistics of large scale peculiar velocity is preferred by peculiar velocity cosmology, since it is free of uncertainties of galaxy density bias entangled in mass-weighted statistics. However, measuring the volume-weighted velocity statistics from galaxy (halo/simulation particle) velocity data is challenging. For the first time, we apply the Kriging interpolation to obtain the volume-weighted velocity field. Kriging is a minimum variance estimator. It predicts the most likely velocity for each place based on the velocity at other places. We test the performance of Kriging quantified by the E-mode velocity power spectrum from simulations. Dependences on the variogram prior used in Kriging, the number $n_k$ of the nearby particles to interpolate and the density $n_P$ of the observed sample are investigated. (1) We find that Kriging induces $1\\%$ and $3\\%$ systematics at $k\\sim 0.1h{\\rm Mpc}^{-1}$ when $n_P\\sim 6\\times 10^{-2} ({\\rm Mpc}/h)^{-3}$ and $n_P\\sim 6\\times 10^{-3} ({\\rm Mpc...

  16. Optical Fiber Fusion Splicing

    CERN Document Server

    Yablon, Andrew D

    2005-01-01

    This book is an up-to-date treatment of optical fiber fusion splicing incorporating all the recent innovations in the field. It provides a toolbox of general strategies and specific techniques that the reader can apply when optimizing fusion splices between novel fibers. It specifically addresses considerations important for fusion splicing of contemporary specialty fibers including dispersion compensating fiber, erbium-doped gain fiber, polarization maintaining fiber, and microstructured fiber. Finally, it discusses the future of optical fiber fusion splicing including silica and non-silica based optical fibers as well as the trend toward increasing automation. Whilst serving as a self-contained reference work, abundant citations from the technical literature will enable readers to readily locate primary sources.

  17. In vivo maximal fascicle-shortening velocity during plantar flexion in humans.

    Science.gov (United States)

    Hauraix, Hugo; Nordez, Antoine; Guilhem, Gaël; Rabita, Giuseppe; Dorel, Sylvain

    2015-12-01

    Interindividual variability in performance of fast movements is commonly explained by a difference in maximal muscle-shortening velocity due to differences in the proportion of fast-twitch fibers. To provide a better understanding of the capacity to generate fast motion, this study aimed to 1) measure for the first time in vivo the maximal fascicle-shortening velocity of human muscle; 2) evaluate the relationship between angular velocity and fascicle-shortening velocity from low to maximal angular velocities; and 3) investigate the influence of musculo-articular features (moment arm, tendinous tissues stiffness, and muscle architecture) on maximal angular velocity. Ultrafast ultrasound images of the gastrocnemius medialis were obtained from 31 participants during maximal isokinetic and light-loaded plantar flexions. A strong linear relationship between fascicle-shortening velocity and angular velocity was reported for all subjects (mean R(2) = 0.97). The maximal shortening velocity (V(Fmax)) obtained during the no-load condition (NLc) ranged between 18.8 and 43.3 cm/s. V(Fmax) values were very close to those of the maximal shortening velocity (V(max)), which was extrapolated from the F-V curve (the Hill model). Angular velocity reached during the NLc was significantly correlated with this V(Fmax) (r = 0.57; P < 0.001). This finding was in agreement with assumptions about the role of muscle fiber type, whereas interindividual comparisons clearly support the fact that other parameters may also contribute to performance during fast movements. Nevertheless, none of the biomechanical features considered in the present study were found to be directly related to the highest angular velocity, highlighting the complexity of the upstream mechanics that lead to maximal-velocity muscle contraction.

  18. Advanced structural design for precision radial velocity instruments

    Science.gov (United States)

    Baldwin, Dan; Szentgyorgyi, Andrew; Barnes, Stuart; Bean, Jacob; Ben-Ami, Sagi; Brennan, Patricia; Budynkiewicz, Jamie; Chun, Moo-Young; Conroy, Charlie; Crane, Jeffrey D.; Epps, Harland; Evans, Ian; Evans, Janet; Foster, Jeff; Frebel, Anna; Gauron, Thomas; Guzman, Dani; Hare, Tyson; Jang, Bi-Ho; Jang, Jeong-Gyun; Jordan, Andres; Kim, Jihun; Kim, Kang-Min; Mendes de Oliveira, Claudia; Lopez-Morales, Mercedes; McCracken, Kenneth; McMuldroch, Stuart; Miller, Joseph; Mueller, Mark; Oh, Jae Sok; Ordway, Mark; Park, Byeong-Gon; Park, Chan; Park, Sung-Joon; Paxson, Charles; Phillips, David; Plummer, David; Podgorski, William; Seifahrt, Andreas; Stark, Daniel; Steiner, Joao; Uomoto, Alan; Walsworth, Ronald; Yu, Young-Sam

    2016-07-01

    The GMT-Consortium Large Earth Finder (G-CLEF) is an echelle spectrograph with precision radial velocity (PRV) capability that will be a first light instrument for the Giant Magellan Telescope (GMT). G-CLEF has a PRV precision goal of 40 cm/sec (10 cm/s for multiple measurements) to enable detection of Earth-like exoplanets in the habitable zones of sun-like stars1. This precision is a primary driver of G-CLEF's structural design. Extreme stability is necessary to minimize image motions at the CCD detectors. Minute changes in temperature, pressure, and acceleration environments cause structural deformations, inducing image motions which degrade PRV precision. The instrument's structural design will ensure that the PRV goal is achieved under the environments G-CLEF will be subjected to as installed on the GMT azimuth platform, including: Millikelvin (0.001 °K) thermal soaks and gradients 10 millibar changes in ambient pressure Changes in acceleration due to instrument tip/tilt and telescope slewing Carbon fiber/cyanate composite was selected for the optical bench structure in order to meet performance goals. Low coefficient of thermal expansion (CTE) and high stiffness-to-weight are key features of the composite optical bench design. Manufacturability and serviceability of the instrument are also drivers of the design. In this paper, we discuss analyses leading to technical choices made to minimize G-CLEF's sensitivity to changing environments. Finite element analysis (FEA) and image motion sensitivity studies were conducted to determine PRV performance under operational environments. We discuss the design of the optical bench structure to optimize stiffness-to-weight and minimize deformations due to inertial and pressure effects. We also discuss quasi-kinematic mounting of optical elements and assemblies, and optimization of these to ensure minimal image motion under thermal, pressure, and inertial loads expected during PRV observations.

  19. Effects of a novel optical conductive fiber post on the microhardness of two resin cement with different curing modes%新型导光性纤维桩对两种固化方式的树脂水门汀显微硬度的影响

    Institute of Scientific and Technical Information of China (English)

    赵希; 熊宇; 王辉; 张从纪

    2016-01-01

    Objective To explore the effects of an optical conductive fiber post on the mechanical property of two resin cement with different curing modes. Methods Sixteen human premolars with single root were randomly divided into two groups, in which an optical conductive fiber post was luted with light-curing (i-TFC) and dual-curing resin cement (Panavia F 2.0), respectively. Dentin slabs with fiber posts located at cervical, middle and apical root were prepared, Knoop microhardness (KHN) were evaluated using microindentation and the relative curing rate was calculated, data was submitted to two-way ANOVA. Results A trend of decreased microhardness and relative curing rate was observed in both groups as the depth in the root increased. For the light-curing group, microhardness and the relative curing rate at the apical area was significantly lower than that at the cervical and middle area in the root (P<0.05). Conclusion Dual-curing resin cements were recommended to achieve higher degree of polymerization within deep root canal when a optical conductive fiber post was used to restore the root.%目的:探讨导光性纤维桩应用于残根修复时,对两种不同固化方式的树脂水门汀机械性能的影响。方法:16颗单根人前磨牙根分为光固化组和双固化组,分别以光固化(i-TFC)和双固化树脂水门汀(Panavia F 2.0)粘结导光性纤维桩并固化。制备纤维桩修复后的根颈段、根中段、根尖段的牙本质片,压痕法测试两组树脂水门汀在根管不同深度的Knoop显微硬度值(KHN)并计算其相对固化率,进行双因素方差分析。结果:随根管深度的增加,两组树脂水门汀的显微硬度和相对固化率均呈下降趋势。光固化树脂水门汀在根尖段的显微硬度值和相对固化率显著低于根颈段和根中段(P<0.05)。结论:导光性纤维桩修复残根时,双固化树脂水门汀有利于在根尖段获得较高的聚合度。

  20. Polypropylene matrix composites reinforced with coconut fibers

    Directory of Open Access Journals (Sweden)

    Maria Virginia Gelfuso

    2011-09-01

    Full Text Available Polypropylene matrix composites reinforced with treated coconut fibers were produced. Fibers chemically treated (alkalization-CCUV samples or mechanically treated (ultrasonic shockwave-CMUV samples were dried using UV radiation. The goal was to combine low cost and eco-friendly treatments to improve fiber-matrix adhesion. Composite samples containing up to 20 vol. (% of untreated and treated coconut fibers were taken from boxes fabricated by injection molding. Water absorption and mechanical properties were investigated according to ASTM D570-98 and ASTM D638-03, respectively. Electrical characterizations were carried out to identify applications of these composites in the electrical sector. NBR 10296-Electrical Tracking Standard (specific to industry applications and conductivity measurements were obtained applying 5 kV DC to the samples. CMUV samples containing 5 vol. (% fiber presented superior tensile strength values (σ~28 MPa compared to the untreated fibers composite (σ~22 MPa or alkali treatment (σ~24 MPa. However, CMUV composites containing 10 vol. (% fiber presented best results for the electrical tracking test and electrical resistivity (3 × 10(7 Ω.m. The results suggest that composites reinforced with mechanically treated coconut fibers are suitable for electrical applications.