Lead zirconate titanate ferroelectric capacitors produced on sapphire and gallium arsenide substrates

Abstract

Pb(Zr_xTi_1?x)O₃ (PZT) based ferroelectric capacitors have been produced at 600°C on R-cut sapphire and Si-doped (100) GaAs substrates using a pulsed laser ablation deposition (PLAD) technique. La_0.5Sr_0.5CoO₃ (LSCO) conducting electrodes deposited using PLAD serve as top and bottom electrodes. X-ray diffraction results show that the PZT film is polycrystalline and phase-pure in both cases. Electrical characterization of the films show remanant polarization in excess of 20 μC/cm₂. Results of long term properties show that these capacitors: are very tolerant to extremely large numbers of switching cycles; retain charges over very long periods of time; and do not show a strong tendency for their dipoles to be imprinted in a preferred direction.     

Inactivation of pectin Methylesterase and Lactobacillus Plantarum by ohmic heating in pomelo juice

The use of ohmic heating (OH) to inactivate damaging elements in pomelo juice was evaluated. The work investigated the effect of frequencies (50–20 000 Hz) on pectin methylesterase (PME) and Lactobacillus plantarum (L. plantarum) in pomelo juice at 30 V cm⁻¹ of electric field strength. The results show that frequency does not affect PME inactivation (P > 0.05) but affects bacterial reduction and has the most efficiency at 60 Hz, followed by 50 Hz, and in the frequency range at or higher than 500 Hz (P < 0.05). Additionally, the inactivation kinetics of PME and L. plantarum and the impact of nonthermal factors were given. The nonthermal element has contributed to the inactivation enhancement of L. plantarum and PME to reduce the necessary treatment temperature and time. The major spoilage bacteria and enzyme destruction in pomelo juice occurred faster under OH than under conventional heating (CH) suggesting that OH can be effectively used to pasteurise pomelo juice.     

Regenerable sulfur adsorbent for liquid phase JP-8 fuel using gold/silica based materials

Applications requiring hydrogen fuel, including portable, mobile and stationary fuel cells for power generation, are increasing. The conversion of JP-8 to hydrogen offers an energy dense feedstock for hydrogen production through fuel reformation. Unfortunately, organic sulfur compounds in logistical fuels, even at part per million levels, can poison reformer and fuel cell catalysts. In this work, adsorbents based on silica supported gold ions and gold nanoparticles were synthesized and evaluated for the adsorptive desulfurization of JP-8 jet fuel. The adsorbents were evaluated with JP-8 fuel containing 430 ppmw sulfur under ambient conditions. The preparation, as well as the sulfur removal and adsorption characteristics for two adsorbents are described in this work.     

Imprint testing of ferroelectric capacitors used for non-volatile memories

Abstract

A set of criteria is presented, based on the polarization versus electric field hysteresis characteristics, which can be used to reveal a tendency towards imprint failure in ferroelectric capacitors. A series of pulsed voltage waveforms, generated by the RT66A ferroelectric tester, are utilized to validate our established criteria for the tendency towards imprinting. The tests have been performed on hetero-structure Pb(Zr_xTi_1?x)O₃(PZT)-based capacitors produced by a pulsed laser ablation depositon technique (PLAD). The loss of retained charge in the ferroelectric capacitors is considered in light of the imprint test methodology. Rates of retention loss and imprint are extracted from the experimental data and treated as separate processes that lead to device failure. The rate of approach towards imprint failure is found to be influenced by the magnitude of the read pulse.     

Modal decomposition technique for multimode fibers

We propose a new solution for modal decomposition in multimode fibers, based on a spectral and spatial imaging technique. The appearance of spurious modes in the spectral and spatial processing of the images at the output of the fiber under test when it has more than two modes is demonstrated theoretically. The new method, which allows us to identify spurious modes, is more accurate, simpler, and faster than previously reported methods. For demonstration, measurements in a standard step-index multimode fiber and a small-core microstructured fiber are carried out successfully.     

Pressure effects and grain growth kinetics in the consolidation of nanostructured fully stabilized zirconia by pulsed electric current sintering

The effect of applied uniaxial pressure on the densification and grain size of nanocrystalline cubic zirconia (c-YSZ) was investigated during sintering by the pulsed electric current sintering (PECS) method. The role of the pressure depended on temperature, being highly significant at lower temperatures and of little significance at higher temperatures. The kinetics of grain growth were determined under PECS conditions. Analysis of the results indicated a grain growth process that is retarded, probably due to the effect of the current on grain boundary energy or dopant segregation. The activation energy for grain growth of c-YSZ was determined as 252 ± 34 kJ mol^?1, a value that is slightly smaller than reported values for microcrystalline samples.     

Parting curve selection and evaluation using an extension of fuzzy MCDM approach

Parting curve selection and evaluation plays an important role in mold design. Multiple criteria decision-making (MCDM) is an effective tool for evaluating and ranking problems involving multiple criteria. In order to select suitable parting curve, several criteria need to be taken into account. Therefore, this paper proposes an extension of fuzzy MCDM approach to solve parting curve selection problem. In the proposed model, the ratings of alternatives and importance weights of criteria for parting curve selection are expressed in linguistic terms. The membership functions of the final fuzzy evaluation value in the proposed model are developed based on the linguistic expressions. To make the procedure easier and more practical, the normalized weighted ratings are defuzzified into crisp values by using a new maximizing set and minimizing set ranking approach to determine the ranking order of alternatives. An example of parting curve evaluation and selection is given. The results show that the proposed approach is very effective in selecting the optimal parting curve for the molded part. Finally, this paper compares the proposed approach with another fuzzy MCDM approach to demonstrate its advantages and applicability.     

Fake finger-vein image detection based on Fourier and wavelet transforms

Recently, finger-vein recognition has received considerable attention. It is widely used in many applications because of its numerous advantages, such as the small capture device, high accuracy, and user convenience. Nevertheless, finger-vein recognition faces a number of challenges. One critical issue is the use of fake finger-vein images to carry out system attacks. To overcome this problem, we propose a new fake finger-vein image-detection method based on the analysis of finger-vein images in both the frequency and spatial domains.This research is novel in five key ways. First, very little research has been conducted to date on fake finger-vein image detection. We construct a variety of fake finger-vein images, printed on A4 paper, matte paper, and overhead projector film, with which we evaluate the performance of our system. Second, because our proposed method is based on a single captured image, rather than a series of successive images, the processing time is short, no additional image alignment is required, and it is very convenient for users. Third, our proposed method is software-based, and can thus be easily implemented in various finger-vein recognition systems without special hardware. Fourth, Fourier transform features in the frequency domain are used for the detection of fake finger-vein images; further, both spatial and frequency characteristics from Haar and Daubechies wavelet transforms are used for fake finger-vein image detection. Fifth, the detection accuracy of fake finger-vein images is enhanced by combining the features of the Fourier transform and Haar and Daubechies wavelet transforms based on support vector machines.Experimental results indicate that the equal error rate of fake finger-vein image detection with our proposed method is lower than that with a Fourier transform, wavelet transform, or other fusion methods.     

An improved CRNN for Vietnamese Identity Card Information Recognition

This paper proposes an enhancement of an automatic text recognition system for extracting information from the front side of the Vietnamese citizen identity (CID) card. First, we apply Mask-RCNN to segment and align the CID card from the background. Next, we present two approaches to detect the CID card’s text lines using traditional image processing techniques compared to the EAST detector. Finally, we introduce a new end-to-end Convolutional Recurrent Neural Network (CRNN) model based on a combination of Connectionist Temporal Classification (CTC) and attention mechanism for Vietnamese text recognition by jointly train the CTC and attention objective functions together. The length of the CTC’s output label sequence is applied to the attention-based decoder prediction to make the final label sequence. This process helps to decrease irregular alignments and speed up the label sequence estimation during training and inference, instead of only relying on a data-driven attention-based encoder-decoder to estimate the label sequence in long sentences. We may directly learn the proposed model from a sequence of words without detailed annotations. We evaluate the proposed system using a real collected Vietnamese CID card dataset and find that our method provides a 4.28% in WER and outperforms the common techniques.