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A metallic (semiconducting) single-wall nanotube contains an irrational (integral) number of carbon hexagons in the pitch. The room-temperature conductivity is higher by two to three orders of magnitude in metallic nanotubes than in semiconducting nanotubes. Tans et al. [Nature386 (1997) 474] measured the electrical currents in metallic single-wall carbon nanotubes under bias and gate voltages, and observed non-Ohmic behaviors. The original authors interpreted their data in terms of a ballistic transport due to the Coulomb blockage on the electron-carrier model. The mystery of why a ballistic electron is not scattered by impurities and phonons is unexplained, however. An alternate interpretation is presented based on the Cooper pair (pairon)–carrier model. Superconducting states are generated by the Bose–Einstein condensation of the ± pairons at momenta 2πℏn/L, where L is the tube length and n a small integer. As the gate voltage changes the charging state of the tube, the superconducting states jump between different n. The normal current peak shapes appearing in the transition are found to be temperature-dependent, which is caused by the electron–optical phonon scattering.

The cello suites of Johann Sebastian Bach exhibit several types of power-law scaling, the best examples of which can be considered fractal in nature. This article examines scaling with respect to the characteristics of melodic interval and its derivative, melodic moment. A new and effective method for pitch-related analysis is described and then applied to a selection of the 36 pieces that comprise the six cello suites.

The performance of a positive tone resist, PMMA, for sub 100 nm patterning of nano-dots using electron beam lithography is to be studied. This optimization is done on a JEOL JBX-6000 FS System. The various parameters such as beam current, resist thickness, dose and electron energies are optimized. This patterning involves greater control over beam parameters so as to reduce aberrations that might arise due to astigmatism. In this respect, the optimization of the beam current parameters is very important, as a narrower beam will minimize scattering effects. These structures will be particularly significant for the fabrication of quantum dot based devices. Nano-dot arrays of dimensions 70 nm with equal spacings of 70 nm were obtained at 100 pA beam current at 50 KeV for a dose of 170 μC/cm².

Carbon nanomaterials have been of great interest in nanoscience and nanotechnology because of their very small size with unique properties and simplicity in structure having only one chemical element. In our laboratory, attempts were made to synthesize carbon nanomaterials through different routes such a CCVD and pyrolysis of solids carbonaceous precursors. Pyrolysis of polyacrylonitrile fibers in presence of a suitable catalyst resulted in formation of straight as well as coil type long carbon nanofibers and tubes along with general-purpose carbon fibers. Similarly, growth of carbon nanotubes was also observed in the coke deposits during pyrolysis of pitches. The yield of CNTs formed was found to increase if the precursors are impregnated with a suitable catalyst solution. These carbon nanostructures have been characterized using XRD, TEM, SEM and TGA.

We investigate the relation between two types of space curves, the Mannheim curves and constant-pitch curves and primarily explicate a method of deriving Mannheim curves and constant-pitch curves from each other by means of a suitable deformation of a space curve. We define a “radius” function and a “pitch” function for any arbitrary regular space curve and use these to characterize the two classes of curves. A few non-trivial examples of both Mannheim and constant pitch curves are discussed. The geometric nature of Mannheim curves is established by using the notion of osculating helices. The Frenet–Serret motion of a rigid body in theoretical kinematics is studied for the special case of a Mannheim curve and the axodes in this case are deduced. In particular, we show that the fixed axode is developable if and only if the motion trajectory is a Mannheim curve.

The response characteristics of a discus data buoy under the action of nonlinear waves are investigated through an experimental set-up in a wave tank. The details of the model, instrumentation, testing conditions and the analysis of the results are presented and discussed in this paper. The nonlinear waves were generated in the wave tank such that their characteristics fall under the Cnoidal and Stokes wave theory regions. The measured wave elevation and responses of the buoy model were analyzed qualitatively through phase-portrait and, quantitatively through spectral and harmonic analysis. In addition, the effects of the nonlinear wave height, wave period and Ursell parameter, U_r, on the response characteristics of the buoy model are addressed. Using a linear Transfer Function (TF) obtained from linear waves, an attempt to estimate the nonlinear-wave spectral density from the buoy model dynamics is made and the uncertainties in such predictions are detailed.

This work presents an automatic, language independent, gender identification technique based on analysis of speech signal. Two methods were considered for this: one involving pitch frequency threshold and the other using artificial neural networks with Mel Frequency Cepstral Coefficients (MFCC) as features. The final classifier combines both the above mentioned techniques. The pitch is determined by computing sub-harmonic to harmonic ratio and a probabilistic neural network is trained using mel-frequency cepstral coefficients. The classifier was tested on sentences in five regional indian languages, namely, Hindi, Bengali, Manipuri, Urdu and Kashmiri apart from English. Scores of the order of 97% for the test sets were obtained for speech of 4 sec duration.

The appendages of fixed T-foil and stern flap had been proven effective for reducing longitudinal motion of WPC (wave-piercing catamaran) by a large number of experiments. However, with the increasing requirements for comfort and stabilization, research on automatically controlled flap and T-foil becomes very meaningful for further improving the seakeeping performance of WPC. In this paper, we introduced vibration wing theory into WPC seakeeping prediction with automatic control hydrofoil, and subsequently analyzed the optimal motion of the T-foil. The numerical prediction agrees well with the experimental results with acceptable error, which shows that the peak value of the pitch motion curve in regular wave of the hybrid-WPC is about 43% less than the bare-hull, and the significant amplitude of pitch decreases by 52% in irregular waves. Based on these results, we can conclude that vibration wing theory is an accurate and effective forecasting method.