By Topic
Skip to Results

Search Results

You searched for: One strand at a time
136 Results returned
Skip to Results
  • Save this Search
  • Download Citations Disabled
  • Save To Project
  • Email
  • Print
  • Export Results
  • Full text access may be available. Click article title to sign in or learn about subscription options.

    One strand at a time [History]

    Matto, G.
    Industry Applications Magazine, IEEE

    Volume: 14 , Issue: 6
    DOI: 10.1109/MIAS.2008.929335
    Publication Year: 2008 , Page(s): 8 - 12

    IEEE Journals & Magazines

    This paper gives the historical background of Okonite Company, an insulated conductor manufacturing for 300 V to 345 kV. Okonite has manufacturing plants and service centers strategically located across the U.S.A. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Vortex Flow in Superconductors

    Yntema, G.B.
    Journal of Applied Physics

    Volume: 39 , Issue: 6
    DOI: 10.1063/1.1656599
    Publication Year: 1968 , Page(s): 2514

    AIP Journals & Magazines

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Case Study of a 20 T- \phi 400 mm Room Temperature Bore Superconducting Outsert for a 45 T Hybrid Magnet

    Watanabe, K. ; Awaji, S. ; Nishijima, G. ; Hamajima, T. ; Kiyoshi, T. ; Kumakura, H. ; Hanai, S. ; Ono, M.
    Applied Superconductivity, IEEE Transactions on

    Volume: 18 , Issue: 2
    DOI: 10.1109/TASC.2008.920546
    Publication Year: 2008 , Page(s): 552 - 555
    Cited by:  Papers (10)

    IEEE Journals & Magazines

    The High Field Laboratory for Superconducting Materials (HFLSM) and the Tsukuba Magnet Laboratory (TML) conducted in collaboration a case study on development of a 50 T-class hybrid magnet. To construct a high magnetic field magnet with compact and energy-saving design as well as with easy operation and maintenance, one has to develop high-strength NbSn strand cables, with maximized superconducting characteristics and which can withstand a large electromagnetic force over 500 MPa. For this purpose, the HFLSM has proposed and investigated the effect of repeated bending treatment (pre bending) on NbSn strands internally reinforced with CuNb stabilizer leading to significant enhancement of the critical current density. In this report we present our results on application of the pre bending effect to the development of high-strength strand cables. The designed prebent-strand cables are composed of three CuNb/Nb3Sn strands (3 times Phi =1.73 mm) and four stainless steel strands ( 4 times Phi =1.73 mm). High-strength CuNb/Nb3Sn strand cables have shown a stress limit of 552 MPa at 0.4% strain, and a critical current of Ic =1000 A at 18.5 T and 2.0 K. For such high-strength strand cables, a 20 T superconducting magnet with a room temperature bore (Phi =400 mm) consisting of five layers made of CuNb/NbSn and two layers of NbTi was designed. The coil parameters are: inner diameter Phi = 440 mm, outer diameter Phi = 1332 mm, coil height 1321 mm, inductance 350 H and magnetic stored energy 144 MJ at 908 A of the operation current. Winding of the coil was experimentally successfully simulated using dummy 3 + 4 strands cable composed of three Cu strands and 4 stainless steel strands with a similar design to the 3 + 4 strands superconducting cable presented above. The 20 T superconducting coil will be used as a 20 T outsert for a 25 T water-cooled resistive insert to obtain a 45 T hybrid magnet. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Understanding the respective roles of UV photons and radicals in cold plasma sterilization

    Moisan, M. ; Saoudi, B. ; Pelletier, J. ; Barbeau, J.
    Plasma Science, 2002. ICOPS 2002. IEEE Conference Record - Abstracts. The 29th IEEE International Conference on

    DOI: 10.1109/PLASMA.2002.1030529
    Publication Year: 2002
    Cited by:  Papers (3)

    IEEE Conference Publications

    Summary form only given. Low-temperature plasma sterilization can be achieved under direct contact with the discharge or in its afterglow. The results to be presented were obtained with B. Subtilis spores subjected to the flowing afterglow of a microwave discharge, at pressures typically below 10 Torrs. As a rule, the sterilization cycle, characterized by the corresponding survival curve (logarithm of the number of living spores as a function of exposure time), takes place in three distinct steps (called phases), each presenting a specific kinetics of inactivation. The analysis of these diagrams as functions of the operating conditions enables one to identify the two principal physico-chemical processes leading to plasma sterilization, namely irradiation of the spore DNA by UV photons and spore erosion by free radicals (e.g., oxygen atoms). The UV photons are emitted by atoms or molecules excited in the afterglow through collisions. Among those directed toward the spore, only a fraction actually penetrates into the spore up to its genetic material, participating in its alteration. A spore is ultimately inactivated when the number of lesions caused to its DNA strands is sufficient to prevent the spore from germinating when put back in a favorable environment. During the first phase, almost all of the isolated spores are inactivated by UV photons, usually in a relatively short period of time (=10 minutes). However, statistically, one spore in a thousand presents a particular resistance to UV irradiation, leading to a considerable slowing down of the inactivation process, well reflected by the longer characteristic time of the second phase of the cycle. For example, spores that are partially or totally covered by other spores or debris of all kinds present a "thickness" superior to that of a single average microorganism. In this case, the erosion process, induced by oxygen atoms forming volatile compounds with the spore material, is of particular importance. It reduce- progressively the distance the photons have to travel within the spore to reach DNA, therefore contributing to an increase of the number of UV photons hitting the genetic material per unit time. Most of our previous work has been achieved with an N/sub 2/-O/sub 2/ post-discharge, where the UV photons mainly result from excited NO molecules, whose population is strongly dependent on the O/sub 2/ percentage in the N/sub 2/-O/sub 2/ mixture. In such a case, it is difficult to fully discriminate damage to the spore due to UV irradiation from that resulting from its erosion (etching) due to oxygen atoms. To separate these two effects, we have used noble gas/O/sub 2/ mixtures, where no O/sub 2/-containing molecules are formed with the carrier gas that could further emit UV photons. Survival curves obtained with the noble gas alone and in the presence of O/sub 2/ seem to indicate that oxygen atoms actually play a secondary role in the spore inactivation, in accordance with our observations in N/sub 2/-O/sub 2/ mixtures. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Development of a 66/6.9kV-2MVA REBCO superconducting transformer

    Iwakuma, M. ; Sakaki, K. ; Tomioka, A. ; Miyayama, T. ; Konno, M. ; Hayashi, H. ; Okamoto, H. ; Gosho, Y. ; Eguchi, T. ; Yoshida, S. ; Suzuki, Y. ; Hirai, H. ; Iijima, Y. ; Saitoh, T. ; Izumi, T. ; Shiohara, Y.
    Applied Superconductivity, IEEE Transactions on

    Volume: PP , Issue: 99
    DOI: 10.1109/TASC.2014.2364615
    Publication Year: 2014 , Page(s): 1

    IEEE Early Access Articles

    We have designed and fabricated a 3φ-66kV/6.9kV- 2MVA transformer with RE1Ba2Cu3O7-δ(REBCO, RE:Rare Earth, Y, Gd etc.) superconducting tapes. It is a 1/10 model of a 3-66kV/6.9kV-20MVA one for a distribution power grid. The superconducting windings were reduced only in current capacity by reducing the number of tapes in parallel conductors. In the primary side, a single REBCO tape with a width of 5 mm was cylindrically wound into 8 layers. In the secondary one, an 8- strand parallel conductor was wound similarly into 2 layers, where each strand was transposed 15 times per one layer. The REBCO tapes for the secondary winding were also scribed by laser into a 3-filament structure to reduce the ac loss. The windings for 3 phases were installed into a GFRP cryostat which had an elliptic-cylinder-shape and three cylindroid bore for an iron core at room-temperature. A Ne turbo-Brayton refrigerator with a cooling capacity of 2kW at 65 K was developed and located close to the transformer. The windings were cooled with subcooled liquid nitrogen at 65 to 70 K, which was forced-flowed by a pump unit between the transformer and the refrigerator. The completed transformer was first tested in liquid nitrogen at 77 K according to the domestic regulation for conventional transformers. The load loss, i.e., ac loss of the windings, was 26.9 W for the rated operation. The dielectric strength was also verified by applying 350 kV impulse voltage and 140 kV ac voltage for 1 minute. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Tip steering for fast imaging in AFM

    Andersson, S.B. ; Jiwoong Park
    American Control Conference, 2005. Proceedings of the 2005

    DOI: 10.1109/ACC.2005.1470337
    Publication Year: 2005 , Page(s): 2469 - 2474 vol. 4
    Cited by:  Papers (8)

    IEEE Conference Publications

    In atomic force microscopy a sharp tip, supported by a cantilevered beam and interacting locally with a sample, is raster-scanned over a surface to build a three dimensional image. Typical scan times are on the order of minutes or longer, depending on the size, resolution, and image quality desired. For a variety of reasons it is of great interest to reduce the time to gather an image. One of the most exciting applications is the imaging in real time of dynamic phenomena such as the motion of single molecules in molecular biology. In many cases the sample to be imaged is string-like, such as nanowires, actin, and DNA strands. In this case most of the imaging time is wasted gathering data about the substrate rather than about the sample. In this work we propose a high-level control algorithm to steer the tip along the string, thereby imaging only the area directly around the sample. This approach focuses the resolution directly where desired and greatly reduces the time to gather an image by reducing the area to be scanned. Depending on the sample, an order of magnitude or better improvement in the imaging time can be achieved. As the algorithm makes no demands on the low level control of the tip it can be combined with approaches aimed at increasing the allowed scanning speed, resulting in even greater reductions in the imaging time. Furthermore, the chances of damaging the tip due to interaction with stray particles on the substrate is greatly reduced since the tip is kept near to the sample. In addition to a simulation study, we present a physical experiment in which a carbon nanotube is imaged using an atomic force microscope controlled by the tip-steering algorithm. To the authors knowledge this is the first reported instance of an image obtained by such high-level feedback control. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Irregular AC losses with long time constants in large cable-in-conduit conductors

    Hamajima, T. ; Kakusho, Y. ; Hoashi, K. ; Tsuda, M. ; Harada, N. ; Yamada, H. ; Takahata, K. ; Satow, T.
    Applied Superconductivity, IEEE Transactions on

    Volume: 13 , Issue: 2 , Part: 2
    DOI: 10.1109/TASC.2003.813082
    Publication Year: 2003 , Page(s): 2384 - 2387
    Cited by:  Papers (4)

    IEEE Journals & Magazines

    A large superconducting coil wound with Cable-in-Conduit (CIC) conductor causes both irregular AC losses that cannot be estimated from short conductor sample test results, and regular AC losses that are proportional to cable twisting pitch squared. We proposed a mechanism forming loops that generated the irregular losses. The CIC conductor is composed of several stages of sub-cables. If one strand on the surface of a sub-cable contacts another strand on the surface of the adjacent sub-cable, the two strands must encounter each other again at the LCM (Least Common Multiplier) distance of all staged cable pitches, and thereby a long loop is formed. We orderly labeled all strands in CIC conductors for the SMES and the LHD. It was found that strands in a triplet were widely displaced from their original positions on one cross section, but contacted each other tightly on the other cross section. This fact suggests that the loop with the large displaced strand links irregularly with external field so that the loops cause the irregular AC losses. Moreover, it indicates that a contacting length of the large displaced strands can be quite long, giving rise to a low contact resistance for the loop, and leading to the long time constants. It is believed that the widely displaced strand are inherent in a CIC conductor. It was demonstrated that the strand surface coated with CuNi was effective to suppress the irregular AC losses. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Stabilization of Cu-Ni based persistent current switch

    Urata, M. ; Yazawa, T. ; Maeda, H. ; Tomisaki, T. ; Kabashima, S. ; Sasaki, K. ; Kumano, T.
    Applied Superconductivity, IEEE Transactions on

    Volume: 3 , Issue: 1 , Part: 4
    DOI: 10.1109/77.233773
    Publication Year: 1993 , Page(s): 586 - 589
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    Stabilization of a persistent current switch with a parallel connection is described. The current transfer behavior for a seven-strand conductor, wound as a persistent current switch, was studied. Each strand current was measured by using Rogowski coils. In the current ramp, negative current flowed into the center strand, which was inverted to a positive direction in about a 2-min time constant. Strand quench was induced by a heater wound in each strand. When one of the outer strands was quenched by its heater, the current was mainly transferred to the nearest three strands including the center strand in about 2 ms. These experimental results agreed well with the calculated results considering the self/mutual inductance for a parallel conductor and the joint resistance. The transferred current of several tens of amperes, which flowed with a few orders of 10000 A/s ramp rate, resulted in the degradation of the whole switch quench current from the conductor critical value.<> View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    IMSH: an iterative heuristic for SRLG diverse routing in WDM mesh networks

    Todimala, A. ; Ramamurthy, B.
    Computer Communications and Networks, 2004. ICCCN 2004. Proceedings. 13th International Conference on

    DOI: 10.1109/ICCCN.2004.1401627
    Publication Year: 2004 , Page(s): 199 - 204
    Cited by:  Papers (9)  |  Patents (1)

    IEEE Conference Publications

    Survivable routing of a connection involves computation of a pair of diverse routes such that at most one route fails when failures occur in the network topology. A subset of links in the network that share the risk of failure at the same time are said to belong to a shared risk link group (SRLG) [J. Strand et al., Feb 2001]. A network with shared risk link groups defined over its links is an SRLG network. A failure of an SRLG is equivalent to the failure of all the links in the SRLG. For a connection to be survivable in an SRLG network, its working and protection paths must be routed on SRLG diverse paths. SRLG diverse routing problem has been proved to be NP-complete in J.Q. Hu (2003). According to the quality of service requirement of a survivable connection request, dedicated protection or shared protection can be used to establish the connection request. With dedicated protection, the connection is established on both the SRLG diverse working and protection paths. The simplest heuristic for computing SRLG diverse path pair is the two-step approach, but it suffers from the trap topology problem. In the previous study by Pin-Han Ho, an iterative heuristic (ITSH) using the two-step approach was proposed to compute the least cost SRLG diverse path pair. Suurballe's algorithm computes a pair of least cost link-disjoint paths between a node pair. In this work, we present a modified Suurballe's heuristic for computing the SRLG diverse routes between a node pair. We then propose an iterative heuristic (IMSH) which uses the modified Suurballe's heuristic for computing the least cost SRLG diverse routes. We also present an 1/2-cost-improvement optimality check criterion for dedicated protection View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    A mechanism causing an additional AC loss in a large CICC coil

    Hamajima, T. ; Yoshida, M. ; Shimamura, H. ; Harada, N. ; Tsuda, M. ; Hanai, S. ; Satow, T.
    Applied Superconductivity, IEEE Transactions on

    Volume: 11 , Issue: 1 , Part: 2
    DOI: 10.1109/77.920211
    Publication Year: 2001 , Page(s): 1860 - 1863
    Cited by:  Papers (7)

    IEEE Journals & Magazines

    A large superconducting coil wound with cable-in-conduit (CIC) conductor caused an additional AC loss which cannot be estimated from short conductor sample test results. It was confirmed that the additional AC loss was generated by long current loops in the CIC conductor. Magnetic field decays of the loops with various long time constants were observed through Hall probes. We propose a mechanism forming the long loops. The CIC conductor is composed of several staged sub-cables. If one strand on the surface of a sub-cable contacts with the other strand on the surface of the adjacent sub-cable, the two strands must encounter each other again at LCM (least common multiplier) distance of all staged cable pitches and thereby result in forming a pair of a long loop. We traced each strand in the CIC according to a method that the sub-cables at all sub-stages rotate around a center of inertia. The long time constants were calculated and their results can explain the data measured in a large SMES coil. The proposed mechanism is effective for estimating the additional AC loss in the coil View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Study of Filament Cracking Under Uniaxial Repeated Loading for ITER TF Strands

    Sheth, M.K. ; Lee, P.J. ; McRae, D.M. ; Sanabria, C.M. ; Starch, W.L. ; Walsh, R.P. ; Jewell, M.C. ; Devred, A. ; Larbalestier, D.C.
    Applied Superconductivity, IEEE Transactions on

    Volume: 22 , Issue: 3
    DOI: 10.1109/TASC.2011.2174554
    Publication Year: 2012 , Article#: 4802504
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    In a tokamak, such as ITER, superconducting strands suffer from bending and uniaxial strain due to Lorentz force loading/unloading and thermal cool down which may de- grade the performance over time due to specific cable-in-conduit conductor (CICC) design choice. Under repeated uniaxial loading the Cu(Sn) matrix which surrounds the brittle filaments allows the possibility of some elastic-plastic deformation that can initiate filament cracking. Here we present a metallographic study of filament cracking under increasing uniaxial loading cycles (0, 1000, 10,000 and 30,000 cycles) for one ITER Toroidal field (TF) bronze-process strand (tested at 0.4%, 0.6% and 1% strain) and one ITER TF internal tin strand (tested at 0.4%, 0.6% and 0.7% strain). Significant cracking of filaments was found at close to the respective fracture limits (strain at which strand breaks under uniaxial tensile loading) for both strands. After 0.6% strain, filament cracking in the bronze-process strand tends to increase with increasing number of loading cycles up to 10,000 and then remains almost constant after increasing the loading cycles from 10,000 to 30,000. The internal tin strand on the other hand showed an increase in filament cracking with increasing loading cycles to 10,000 up to 0.6% strain. For both types of strand and in all conditions the cracks were most likely to be found adjacent to voids. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Experimental and Theoretical Investigation of the Diffusion of Sn in Internal-Tin Nb3 Sn

    Dhaka, R.K. ; Sumption, Michael D. ; Xuan Peng ; Gregory, E. ; Tomsic, M. ; Collings, E.W.
    Applied Superconductivity, IEEE Transactions on

    Volume: 17 , Issue: 2 , Part: 3
    DOI: 10.1109/TASC.2007.898221
    Publication Year: 2007 , Page(s): 2655 - 2659

    IEEE Journals & Magazines

    The diffusion of Sn through the interfilamentary matrix within a subelement and the formation the of associated Cu-Sn phases was observed experimentally for several different Nb3Sn internal-Sn type strand subelements during the pre-reaction part of a heat treatment. Two different pre-reaction heat treatment schedules were investigated (10degC/hr ramp up, pausing at 185degC/24 hr + 25degC/hr ramp up, pausing at 340degC/48 hr as well as 10degC/hr ramp up, pausing at 210degC/48 hr + 25degC/hr ramp up, pausing at 400degC/48 hr). Four subelement types were measured, one without Ti, the others with Ti added either as NbTi rod replacements for selected Nb(Ta) filaments, or as wraps around each individual Nb(Ta) filament. In all but one case the majority of the filaments were a Nb-7.5 wt%Ta. A simple model was developed to determine the time and temperature dependence of Sn-diffusion through the Cu matrix of the subelements. The output of the model, in the form of radial positions of eta, epsiv, and a phases as a function of time during the pre-reaction heat treatment process, was compared to the experimental results. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Effect of Chrome Coating on Resistance of Sintered Joint for ITER Central Solenoid

    Martovetsky, N.N. ; Irick, D.K.
    Applied Superconductivity, IEEE Transactions on

    Volume: 24 , Issue: 3
    DOI: 10.1109/TASC.2013.2281526
    Publication Year: 2014 , Article#: 4800303

    IEEE Journals & Magazines

    The ITER Central Solenoid has 36 interpancake joints. The joints are required to have a resistance below 4 nOhm at 45 kA at 4.5 K. The US ITER Project Office developed and qualified a sintered joint for the interpancake joints that consistently showed exceptionally low dc resistance of 0.13 nOhm at up to 80 kA in the self-field of about 1.5 T. To provide a good current distribution in the joint, we removed chrome plating from the strands in this area. We built and tested four samples of the sintered joints before 2012. Such a low resistance prompted an investigation of the possibility of leaving the chromium on the strands during the joint preparation and still staying well below allowable resistance. Although removal of the chrome plating is not a very labor-intensive or time-consuming operation, it requires handling of harmful fumes and produces a solution containing hexavalent Cr, which is a hazardous substance. Elimination of the Cr removal step is a simplification of the fabrication process and therefore is a desirable act. We built two identical racetrack samples of the sintered joint and tested them in our joint test apparatus. One sample had Cr removed from the strands, the other had Cr intact. This paper provides a description of the test samples, fabrication steps, and results of the dc resistance measurements. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Performance of WDM Mesh Networks with Limited Traffic Grooming Resources

    Awwad, O. ; Al-Fuqaha, A. ; Rayes, A.
    Wireless and Optical Communications Networks, 2007. WOCN '07. IFIP International Conference on

    DOI: 10.1109/WOCN.2007.4284132
    Publication Year: 2007 , Page(s): 1 - 5

    IEEE Conference Publications

    While a single fiber strand in wavelength division multiplexing (WDM) has over a terabits-per-second data rate and a wavelength channel has over a gigabits-per-second transmission speed, the network may still be required to support traffic requests at rates that are lower than the full wavelength capacity. To avoid assigning an entire light path to a small request, many researchers have looked at adding traffic grooming to the Routing and Wavelength Assignment (RWA) problem. In this work, we consider the RWA problem with traffic Grooming (GRWA) for mesh networks under dynamic lightpath connection requests. Like RWA, GRWA is also NP-Complete. While most of the previous work in this field focuses on optical networks without grooming or with full grooming capabilities, in this work we study the blocking performance of optical networks with sparse traffic grooming resources. This paper proposes a novel heuristic for dynamic traffic grooming in WDM mesh networks, where connections arrive one at a time and hold for random time durations. The strength of the proposed heuristic stems from its simplicity, applicability to large-scale networks, and efficiency compared to other heuristics proposed in the literature. Our simulation results demonstrate that deploying traffic grooming resources on the edge of optical networks is more cost effective and results in a similar blocking performance to that obtained when distributing the grooming resources throughout the optical network domain. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Cyclic fatigue and wear in deepwater polyester mooring systems

    Ayers, R.R. ; Aksu, S.B.
    OCEANS 2009, MTS/IEEE Biloxi - Marine Technology for Our Future: Global and Local Challenges

    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    Fatigue life of deepwater mooring lines is a very important issue in the design of mooring systems for offshore structures. Polyester ropes experience cyclic loading over the life of the mooring, and the remaining strength of those ropes is reduced over time as individual fibers comprising the rope are broken. Fatigue and wear testing of polyester fibers and polyester subropes has shown that two distinct mechanisms are at work: (1) true fatigue failures in single polyester fibers and (2) fiber damage due to cyclic wear caused by subrope strands rubbing against one another near the toe of eye splices. This paper compares and contrasts these key issues of fiber fatigue and subrope strand-on-strand cyclic wear. A new method was developed to test fretting wear of subrope strands subjected to cyclic loading. This method, called the 20-Hurricane method, has been demonstrated and found to constitute a strand-on-strand abrasion wear method conceptually similar to the yarn-on-yarn abrasion test methods used for yarns, rather than strands. The test can measure both strength reduction and maximum elongation performance of polyester subrope designs due to damage from a series of 20 hurricanes over a 20-year period. Test results for various subrope designs are described, and the designs are evaluated in terms of reduction in subrope strength due to the effects of cyclic wear. The authors propose that the 20-Hurricane test be adopted as a ¿benchmark¿ by industry for qualification testing of different designs and brands of polyester rope, and types of splices and marine finishes. Other potential uses of the 20-Hurricane test method for synthetic fiber ropes are also proposed. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    An Accurate DNA Sensing and Diagnosis Methodology Using Fabricated Silicon Nanopores

    Bhattacharya, S. ; Nair, Sankar ; Chatterjee, A.
    Circuits and Systems I: Regular Papers, IEEE Transactions on

    Volume: 53 , Issue: 11
    DOI: 10.1109/TCSI.2006.884484
    Publication Year: 2006 , Page(s): 2377 - 2383

    IEEE Journals & Magazines

    Nanopore-based biomolecular sensing is an emerging nanotechnology which relies on the ability to measure changes in ionic conductance of single nanoscale pores as biomolecular analytes are driven through them, one at a time, by an applied electric field. Nanopores constructed from self-assembled proteins as well as using silicon-based fabrication techniques have been demonstrated to allow sizing and identification of DNA, RNA, proteins, and other biomolecules many times faster than with current technology. Despite the potential of nanopore sensing to produce "next generation" biomolecule analysis devices, its current demonstrations are based on the use of a simple dc stimulus across the nanopore. As a result, the resolution obtained is insufficient for many practical applications. In this paper, we report a novel diagnosis methodology for nanopore sensors based on optimization of a generalized electrical stimulus and a microscopic model of the biomolecule transport process. This methodology is applied to analyze the size distribution of an arbitrary mixture of DNA strands, which is a critical step in DNA sequencing. A transport model for long polymers in nanopores is built and parameterized to reproduce existing experimental data. The electrical stimulus is optimized "on-the-fly" using the model, to obtain a significant increase in the sizing resolution for any given range of DNA sizes and hence a clear identification of all sizes of DNA in the mixture. Hence, it is proposed that nanopore-based DNA sensing can be advanced significantly incurring no (or minimal) hardware overhead, by a combination of optimized stimuli and microscopic transport modeling View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Long time constants of irregular AC coupling losses in a large superconducting coil

    Hamajima, T. ; Harada, N. ; Satow, T. ; Shimamura, H. ; Takahata, K. ; Tsuda, M.
    Applied Superconductivity, IEEE Transactions on

    Volume: 12 , Issue: 1
    DOI: 10.1109/TASC.2002.1018714
    Publication Year: 2002 , Page(s): 1616 - 1619
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    A large superconducting coil wound with Cable-in-Conduit (CIC) conductor caused an irregular AC loss that cannot be estimated from short conductor sample test results. It was confirmed that the irregular AC loss was generated by long current loops in the CIC conductor. We proposed a mechanism forming the long loops. The CIC conductor is composed of several staged sub-cables. If one strand on the surface of a sub-cable contacts with the other strand on the surface of the adjacent sub-cable, the two strands must encounter each other again at LCM (Least Common Multiplier) distance of all staged cable pitches and thereby result in forming a pair of a long loop. We measured cross over point contact resistance between two strands making the long loop. The calculated time constants of the long loops were shorter than the observed ones. We orderly labeled all strands in a real CIC conductor, disassembling carefully the cable after peeling the conduit. It was found that the strands in a triplet were widely displaced from their original positions, and thereby their contacting lengths became longer than cross over ones to form line contacts. This fact can make the time constant. of the loop longer and hence can explain the observed long time constants. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Small sized MFCG for driving a high impedance load

    Hernandez, J.-C. ; Neuber, A.A. ; Dickens, J.C. ; Kristiansen, M.
    Pulsed Power Conference, 2003. Digest of Technical Papers. PPC-2003. 14th IEEE International

    Volume: 2
    DOI: 10.1109/PPC.2003.1277995
    Publication Year: 2003 , Page(s): 1065 - 1068 Vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    End-initiated small volume magnetic flux compression generators (MFCG) have at least one order of magnitude higher energy density (by weight or volume) than capacitive energy storage with similar discharge time characteristics. Since the prime energy is built into the MFCG in form of HE, the capacitor looses even more ground if the necessary prime energy source and the charging supply are included in the weight/volume balance. However, simple MFCGs with a single helix produce high output energy only into low inductance loads, thus producing several 100 kA of current at a voltage level of only a few 10 kV. Many pulsed power devices require less current but a considerably higher voltage level. Two approaches for achieving a higher output voltage level, both utilizing two staged MFCGs, have been reported in the open literature. The first employs a more traditional transformer coupling; the second relies on a dynamic transformer or flux-trapping scheme. Although the traditional transformer coupling has theoretically the better efficiency, we chose the latter approach for our generator design, mostly since it requires a smaller number of components. Our generator has a total length of 250 mm, a helix inner diameter of 51 mm, and is wound with Teflon insulated stranded wire of different sizes in the range from AWG 12 to AWG 22. We have presently achieved an energy gain of /spl sim/ 8 and will discuss the generator performance based on experimental current/voltage waveforms. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Electromagnetic and mechanical AC loss of an ITER TF model coil conductor (DP4) under transverse cyclic loading

    Nijhuis, A. ; Noordman, N.H.W. ; ten Kate, H.H.J. ; Mitchell, N.
    Applied Superconductivity, IEEE Transactions on

    Volume: 10 , Issue: 1
    DOI: 10.1109/77.828303
    Publication Year: 2000 , Page(s): 588 - 591
    Cited by:  Papers (4)

    IEEE Journals & Magazines

    Energising a coil results in a transverse force on the strands pushing the cable towards one side of the jacket. This load causes a transverse compressive strain in strands and in particular in strand crossover points. Besides this, contact surfaces interfere by micro-sliding resulting in friction and anomalous contact resistance behaviour versus force. Two Central Solenoid Model Coil conductors have been tested previously in a cryogenic press and now the experimental results are presented for the Toroidal Field Model Coil (TFMC) conductor (DP4). The press can transmit a variable (cyclic) force of at least 650 kN/m directly to a cable section of 400 mm at 4.2 K. The magnetisation of the conductor and the interstrand resistance (R/sub c/) between various strands inside the cable can be measured by varying pressure. The force on the cable and the displacement are monitored simultaneously in order to determine the effective cable Young's modulus and the mechanical heat generation due to friction and deformation. The mechanical heat generation, the coupling loss time constant n/spl tau/ and the R/sub c/ of the full-size ITER TFMC conductor have been studied under load up to 40 full loading cycles. The evolution of R/sub c/ is comparable to the behaviour found for the CS Model Coil type of conductors. A significant decrease of the cable coupling current time constant, n/spl tau/ and mechanical heat generation after cyclic loading is found. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Image processing technique for segmenting microstructural porosity of laser-welded thermoplastics

    Leboeuf, K. ; Makaremi, I. ; Muscedere, R. ; Ahmadi, M.
    Electronics, Circuits and Systems (ICECS), 2011 18th IEEE International Conference on

    DOI: 10.1109/ICECS.2011.6122385
    Publication Year: 2011 , Page(s): 760 - 763

    IEEE Conference Publications

    Plastics are used in a truly vast number of applications, and research is continously carried out to improve every aspect of the plastics industry. A recent study of laser transmission welding [1] required cross-sectional images of the weld's microstructure to be analyzed for the presence of pores, which are tiny bubbles that may form during the weld process. It is believed that the number and size of pores may be indicative of the weld strength [1]. The current state of the art for detecting these pores involves manually drawing a contour around each one; a laborious process given that a typical sample may have hundreds-to-thousands of pores. This paper presents a segmentation system for classifying the pixels of a microstructural image of a thermoplastic laser weld as either belonging to a pore or the background. The algorithm is robust in terms of dealing with noise from flbreglass strands, cloudy pores, and varying exposure time. On average, it is estimated that the proposed algorithm is able to correctly classify pores at a rate of approximately 90% without requiring any user intervention. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Seatrack Web forecasts and backtracking of oil spills - an efficient tool to find illegal spills using AIS

    Ambjorn, C.
    US/EU-Baltic International Symposium, 2008 IEEE/OES

    DOI: 10.1109/BALTIC.2008.4625512
    Publication Year: 2008 , Page(s): 1 - 9
    Cited by:  Papers (3)

    IEEE Conference Publications

    Seatrack Web is a fully operational oil drift forecasting system. It covers the Baltic Sea and part of the North Sea. The system is available over the Internet and has the latest weather and ocean forecasts, thus giving the user the best possible decision tool in an oil combating situation. The drift model calculates the three-dimensional movements of substances or objects at sea, including sinking, stranding and turbulent dispersion. For oils, the evaporation, emulsification and wave-induced vertical dispersion are also calculated. Seatrack Web is the HELCOM system for forecasting of oil drift, and the primary users are oil combating authorities in the countries surrounding the Baltic Sea. It has been in operation since the early 1990s. The system now includes several new features, where a coupling to an AIS (Automatic Identification System) ship track data base is the most important. When finding a spill in the sea, it is possible to make a backtracking calculation with the system. The result shows every hour the location of the oil back in time. Adding AIS data to those oiled areas shows clearly which ships have been close to the oil during the whole calculation period. The system then fetches new ship tracks in space and time depending on the changing positions of the oil. A large number of possible ships are often found, and those can then be deleted successively after analyses and more information about the circumstances. The first year of experience with using AIS in Seatrack Web have led to many suggestions for improvement. It now, for instance, works faster to identify the suspected ships and it is also easier to ignore irrelevant ships. One valuable new feature is that if AIS data are missing it is possible to take those data from the log book and fill in so the ship track will be completed, thus having correct information when analysing the situation. During 2008 satellite information will be shown in the map, which simplifies the identification of illega- - l polluters even further. The satellite image can also show an ongoing release of a spill, by showing a ship connected to the oil while releasing it. Two radar satellites will be used, RADARSAT 1 and ENVISAT. A case with all information included can also be saved to show as evidence in court at later occasions as animation or special pictures. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Finding the Site of Origin and Velocity of Propagation in a Short One-Dimensional Strand from Two Extracellular Waveforms

    Barr, R.C.
    Biomedical Engineering, IEEE Transactions on

    Volume: BME-31 , Issue: 8
    DOI: 10.1109/TBME.1984.325423
    Publication Year: 1984 , Page(s): 546 - 550
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    In cardiac muscle times of excitation, the site of origin of excitation and propagation velocity usually are determined from the intrinsic deflections of a collection of extracellular waveforms. Separate waveforms are measured from each site for which an excitation time is to be found. Most of the information in each measured waveshape is discarded, even though waveshape features have been shown to be closely related to propagation characteristics. The objective of this paper is to examine the possibility of more fully utilizing all of the information in the extracellular waveform. Would a small number of measured waveforms, used more completely, be sufficient to find the site of origin, propagation velocity, and excitation times? A computer simulation of intra-and extracellular excitation along a one-dimensional cylindrical cardiac strand provided the framework for the evaluation. The dimensions and the-conductivity of the strand and the action potential shape were assumed known. Extracellular waveforms were simulated at 2 of 51 points on the strand and thereafter taken to be "measurements.?" The objectives were to calculate, from the "measured" waveforms, the site of origin of excitation (possibly anywhere along the strand), the speed of propagation, and the times of excitaion at all 51 points. Propagation speed was assumed constant, but of unknown magnitude, in both directions away from the site of excitation. Notable results of the study include correctly differentiating among different sequences of excitation having identical time differences between the intrinsic deflections of the two known extracellular waveforms. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Cu Stabilized \hbox {Nb}_{3}\hbox {Al} Strands for the High Field Accelerator Magnet

    Kikuchi, A. ; Yamada, R. ; Barzi, E. ; Lamm, M. ; Takeuchi, T. ; Turrioni, D. ; Zlobin, A.V.
    Applied Superconductivity, IEEE Transactions on

    Volume: 18 , Issue: 2
    DOI: 10.1109/TASC.2008.921944
    Publication Year: 2008 , Page(s): 1026 - 1030
    Cited by:  Papers (18)

    IEEE Journals & Magazines

    Characteristics of developed Nb3Al strand though the RHQT (rapid heating/quenching and transformation) process are described. One kilometer-long copper stabilized Nb3Al round strands were economically fabricated with ion-plating and electroplating. The copper electroplating was successfully done with the high velocity of 5 m/h. A strong bonding between the copper and the precursor was achieved, and the mechanical rolling test did not show the separation of the copper stabilizer from the precursor. The rolled Nb3Al strands showed no degradation both in critical current density and RRR value. Magnetic instability at 4.2 K at low fields was apparently improved on the F3 strand, relative to the previously F1 stand because a tantalum was used for the interfilament matrix of precursor. The large magnetic flux jumps, which were observed with the Fl strand, were suppressed at 4.2 K, although appeared again below 3.0 K. The twisted strands are shown to be effective to reduce the time-dependent eddy current coupling. It was obtained 48 mum of Deff on F3 strand with twist pitch of 45 mm. In addition, the transverse pressure test for the Fl Nb3Al strand was performed at 4.2 K and 12 T. The critical current did not degrade with the transverse pressure up to 210 MPa. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Accurate AC measurements of standard resistors between 1 and 20 Hz

    Delahaye, F. ; Bournaud, D.
    Instrumentation and Measurement, IEEE Transactions on

    Volume: 42 , Issue: 2
    DOI: 10.1109/19.278566
    Publication Year: 1993 , Page(s): 287 - 291
    Cited by:  Papers (14)

    IEEE Journals & Magazines

    A new version of an AC bridge for low-frequency (1-20-Hz) measurements of resistance ratios is designed. The bridge is based on an alternating current comparator operating at room temperature. The current comparator uses a single magnetic core of high permeability provided with a tuned detection winding enclosed in electrostatic and magnetic shields. Comparators with ratios equal to 1/1, 100/1, 64.53/1, and 129.06/1 were built, allowing the calibration of 1- and 100-Ω resistance standards in terms of the quantized Hall resistance. Ratio windings are formed by the series connection of strands from a set of individually guarded cables, a technique which provides low ratio error, not exceeding a few parts in 109 at 1 Hz. The AC behavior of 1-Ω DC standard resistors from different manufacturers is studied using this bridge. The time constant of these resistors is on the order of 1 μs. If the frequency does not exceed 1 Hz, the AC/DC resistance difference due to eddy currents in the metallic can enclosing the resistors is lower than one part in 109. At 1 Hz, the AC-DC difference due to the Peltier effect is found to be less than a few parts in 109, with the exception of two particular resistors for which the difference was on the order of one part in 108 View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Effect of layout on magnetization of NbTi strands

    Vedernikov, G.P. ; Shikov, A.K. ; Potanina, L.V. ; Gubkin, I.N. ; Nikulin, A.D. ; Novikov, S.I. ; Novikov, M.S.
    Applied Superconductivity, IEEE Transactions on

    Volume: 13 , Issue: 2 , Part: 3
    DOI: 10.1109/TASC.2003.812319
    Publication Year: 2003 , Page(s): 3362 - 3365

    IEEE Journals & Magazines

    Magnetization measurements at background fields up to 3 T were performed for 4 NbTi strands of various layouts both at a superposition of a sinusoidal varying field with a frequency of 0.5-3 Hz and at fast exponential sweep of external field. Strand layouts are distinguished by filament diameter, Cu/non-Cu ratio and filament zone location in the cross section of the wires. One of the strands contains resistive barriers of CuNi alloy, which surround a filament zone on the both sides. Using magnetization loops, the total and coupling losses for each strand have been calculated along with time constant values. The results showed that no matter how the field variation was performed, minimum losses as well as minimum time constant values were obtained for the sample with smallest filament diameter, having rather small copper core area (4.5%) and resistive CuNi barriers. For the sample with the same filament size but copper core area of 25% both losses and time constant were maximum. View full abstract»

Skip to Results

SEARCH HISTORY

Search History is available using your personal IEEE account.