5,999 research outputs found

    A method of solving sets of nonlinear algebraic equations Progress report

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    Methods for solving nonlinear algebraic equations in computer programs for nuclear magnetic resonance spectroscop

    Thermal analysis comparison between two random glass fibre reinforced thermoplastic matrix composites bonded by adhesives using microwaves: preliminary results

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    [Abstract]: This paper compares the thermal analysis of two types of random glass fibre reinforced thermoplastic matrix composites joined by adhesives using microwave energy. Fixed frequency, 2.45 GHz, microwave facility is used to join thirty three percent by weight random glass fibre reinforced polystyrene composite [PS/GF (33%)] and thirty three percent by weight random glass fibre reinforced low density polyethylene composite [LDPE/GF (33%)]. The facility used is shown in Figure 1. With a given power level, the composites were exposed to various exposure times to microwave irradiation. The primer or coupling agent used was 5-minute two-part adhesive. The heat distribution of the samples of the two types of composites was analysed and compared. The relationship between the heat distribution and the lap shear strength of the samples was also compared and discussed

    Inverter-Based Low-Voltage CCII- Design and Its Filter Application

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    This paper presents a negative type second-generation current conveyor (CCII-). It is based on an inverter-based low-voltage error amplifier, and a negative current mirror. The CCII- could be operated in a very low supply voltage such as ±0.5V. The proposed CCII- has wide input voltage range (±0.24V), wide output voltage (±0.24V) and wide output current range (±24mA). The proposed CCII- has no on-chip capacitors, so it can be designed with standard CMOS digital processes. Moreover, the architecture of the proposed circuit without cascoded MOSFET transistors is easily designed and suitable for low-voltage operation. The proposed CCII- has been fabricated in TSMC 0.18μm CMOS processes and it occupies 1189.91 x 1178.43μm2 (include PADs). It can also be validated by low voltage CCII filters

    Pulsed THz radiation due to phonon-polariton effect in [110] ZnTe crystal

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    Pulsed terahertz (THz) radiation, generated through optical rectification (OR) by exciting [110] ZnTe crystal with ultrafast optical pulses, typically consists of only a few cycles of electromagnetic field oscillations with a duration about a couple of picoseconds. However, it is possible, under appropriate conditions, to generate a long damped oscillation tail (LDOT) following the main cycles. The LDOT can last tens of picoseconds and its Fourier transform shows a higher and narrower frequency peak than that of the main pulse. We have demonstrated that the generation of the LDOT depends on both the duration of the optical pulse and its central wavelength. Furthermore, we have also performed theoretical calculations based upon the OR effect coupled with the phonon-polariton mode of ZnTe and obtained theoretical THz waveforms in good agreement with our experimental observation.Comment: 9 pages, 5 figure

    Temperature dependent d-d excitations in manganites probed by resonant inelastic x-ray scattering

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    We report the observation of temperature dependent electronic excitations in various manganites utilizing resonant inelastic x-ray scattering (RIXS) at the Mn K-edge. Excitations were observed between 1.5 and 16 eV with temperature dependence found as high as 10 eV. The change in spectral weight between 1.5 and 5 eV was found to be related to the magnetic order and independent of the conductivity. On the basis of LDA+U and Wannier function calculations, this dependence is associated with intersite d-d excitations. Finally, the connection between the RIXS cross-section and the loss function is addressed.Comment: 5 pages, 5 figure

    Thermally induced 0-pi phase transition in Josephson junctions through a ferromagnetic oxide film

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    We investigate the Josephson transport through a ferromagnetic oxide film, e.g., La2_2BaCuO5_5, theoretically. Using the recursive Green's function technique, we found the formation of a pi-junction in such systems. Moreover the 0-pi phase transition is induced by increasing the temperature. Such ferromagnetic-oxide based Josephson junctions may become an element in the architecture of future quantum computers.Comment: 4 pages, 3 figure

    Experimental observation of the crystallization of a paired holon state

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    A new excitation is observed at 201 meV in the doped-hole ladder cuprate Sr14_{14}Cu24_{24}O41_{41}, using ultraviolet resonance Raman scattering with incident light at 3.7 eV polarized along the direction of the rungs. The excitation is found to be of charge nature, with a temperature independent excitation energy, and can be understood via an intra-ladder pair-breaking process. The intensity tracks closely the order parameter of the charge density wave in the ladder (CDWL_L), but persists above the CDWL_L transition temperature (TCDWLT_{CDW_L}), indicating a strong local pairing above TCDWLT_{CDW_L}. The 201 meV excitation vanishes in La6_{6}Ca8_{8}Cu24_{24}O41+δ_{41+\delta}, and La5_{5}Ca9_{9}Cu24_{24}O41_{41} which are samples with no holes in the ladders. Our results suggest that the doped holes in the ladder are composite bosons consisting of paired holons that order below TCDWT_{CDW}.Comment: Accepted for publication in Physical Review Letters (4 figures

    Development of coconut oil/capric acid eutectic phase change material with graphene as latent thermal energy storage.

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    In this study, a eutectic mixture of coconut oil (CO)-capric acid (CA) was synthesised and investigated with the aim of producing newly eutectic phase change materials (PCMs) with improved thermal properties as thermal energy storage (TES). Although eutectic fatty acids have been widely studied, the information on the thermal properties of the CO-CA eutectic mixture is very limited to the authors' knowledge. Coconut oil offers good thermal and chemical stability with acceptable latent heat and melting temperature. The thermal properties of the eutectic mixture were enhanced by graphene addition at 1, 3, 5, and 7 wt% concentrations. The surfactant was added to the mixture to avoid the sedimentation of graphene. The material characterisation techniques include thermal conductivity measurement, Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), and Thermal Gravimetric (TG) analysis. The results revealed that the pure eutectic CO-CA has a melting point of 23.5°C with a latent heat of 110 J/g. With the addition of graphene, the melting point of the mixture is 22.8°C, and the latent heat is 103 J/g. Overall, the findings showed that the thermal conductivity improved by 21.7% for 7wt% graphene concentration. The spectra from FTIR and TG analysis showed that the mixture offers thermal and chemical stability. The promising findings in this study showed that the newly developed eutectic mixture with improved thermal properties makes them favourable to be used as TES for low-temperature applications
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