1,334 research outputs found

    Quantitative Assessment of Flame Stability Through Image Processing and Spectral Analysis

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    This paper experimentally investigates two generalized methods, i.e., a simple universal index and oscillation frequency, for the quantitative assessment of flame stability at fossil-fuel-fired furnaces. The index is proposed to assess the stability of flame in terms of its color, geometry, and luminance. It is designed by combining up to seven characteristic parameters extracted from flame images. The oscillation frequency is derived from the spectral analysis of flame radiation signals. The measurements involved in these two methods do not require prior knowledge about fuel property, burner type, and other operation conditions. They can therefore be easily applied to flame stability assessment without costly and complex adaption. Experiments were carried out on a 9-MW heavy-oil-fired combustion test rig over a wide range of combustion conditions including variations in swirl vane position of the tertiary air, swirl vane position of the secondary air, and the ratio of the primary air to the total air. The impact of these burner parameters on the stability of heavy oil flames is investigated by using the index and oscillation frequency proposed. The experimental results obtained demonstrate the effectiveness of the methods and the importance of maintaining a stable flame for reduced NOx emissions. It is envisaged that such methods can be easily transferred to existing flame closed-circuit television systems and flame failure detectors in power stations for flame stability monitoring

    Genetic heterogeneity of pseudoxanthoma elasticum: the Chinese signature profile of ABCC6 and ENPP1 mutations.

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    Pseudoxanthoma elasticum (PXE), an autosomal recessive disorder characterized by ectopic mineralization, is caused by mutations in the ABCC6 gene. We examined clinically 29 Chinese PXE patients from unrelated families, so far the largest cohort of Asian PXE patients. In a subset of 22 patients, we sequenced ABCC6 and another candidate gene, ENPP1, and conducted pathogenicity analyses for each variant. We identified a total of 17 distinct mutations in ABCC6, 15 of them being, to our knowledge, previously unreported, including 5 frameshift and 10 missense variants. In addition, a missense mutation in combination with a recurrent nonsense mutation in ENPP1 was discovered in a pediatric PXE case. No cases with p.R1141X or del23-29 mutations, common in Caucasian patient populations, were identified. The 10 missense mutations in ABCC6 were expressed in the mouse liver via hydrodynamic tail-vein injections. One mutant protein showed cytoplasmic accumulation indicating abnormal subcellular trafficking, while the other nine mutants showed correct plasma membrane location. These nine mutations were further investigated for their pathogenicity using a recently developed zebrafish mRNA rescue assay. Minimal rescue of the morpholino-induced phenotype was achieved with eight of the nine mutant human ABCC6 mRNAs tested, implying pathogenicity. This study demonstrates that the Chinese PXE population harbors unique ABCC6 mutations. These genetic data have implications for allele-specific therapy currently being developed for PXE

    The Analysis of Peasant Household's Credit Behavior

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    AbstractPeasant household's credit behavior not only affect the financial ability of the peasant household, but also influence the credit decisions of the rural financial institution, consequently impact on the development of the Chinese rural economic and the peasant household economic. This paper, based on the credit behavior of peasant household in the process of the Chinese rural economic development11Peasant household's credit behavior is the credit behavior under the comprehensive influence of the repayment capacity and willingness, in which repayment capacity is the key element., analysis the credit behavior game in rural credit and loan process between peasant households and rural financial institution, and the game among peasant households in rural joint warrant process. Finally, provides methods to improve the credit behavior of peasant household in credit game

    Modulation of the thermodynamic, kinetic and magnetic properties of the hydrogen monomer on graphene by charge doping

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    The thermodynamic, kinetic and magnetic properties of the hydrogen monomer on doped graphene layers were studied by ab initio simulations. Electron doping was found to heighten the diffusion potential barrier, while hole doping lowers it. However, both kinds of dopings heighten the desorption potential barrier. The underlying mechanism was revealed by investigating the effect of doping on the bond strength of graphene and on the electron transfer and the coulomb interaction between the hydrogen monomer and graphene. The kinetic properties of H and D monomers on doped graphene layers during both the annealing process (annealing time t0=t_0 =300 s) and the constant-rate heating process (heating rate α=\alpha =1.0 K/s) were simulated. Both electron and hole dopings were found to generally increase the desorption temperatures of hydrogen monomers. Electron doping was found to prevent the diffusion of hydrogen monomers, while the hole doping enhances their diffusion. Macroscopic diffusion of hydrogen monomers on graphene can be achieved when the doping-hole density reaches 5.0×10135.0\times10^{13} cm−2^{-2}. The magnetic moment and exchange splitting were found to be reduced by both electron and hole dopings, which was explained by a simple exchange model. The study in this report can further enhance the understanding of the interaction between hydrogen and graphene and is expected to be helpful in the design of hydrogenated-graphene-based devices.Comment: Submitte

    The Microsoft System for VoxCeleb Speaker Recognition Challenge 2022

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    In this report, we describe our submitted system for track 2 of the VoxCeleb Speaker Recognition Challenge 2022 (VoxSRC-22). We fuse a variety of good-performing models ranging from supervised models to self-supervised learning(SSL) pre-trained models. The supervised models, trained using VoxCeleb-2 dev data, consist of ECAPA-TDNN and Res2Net in a very deep structure. The SSL pre-trained models, wav2vec and wavLM, are trained using large scale unlabeled speech data up to million hours. These models are cascaded with ECAPA-TDNN and further fine-tuned in a supervised fashion to extract the speaker representations. All 13 models are applied with score normalization and calibration and then fused into the the submitted system. We also explore the audio quality measures in the calibration stage such as duration, SNR, T60, and MOS. The best submitted system achieves 0.073 in minDCF and 1.436% in EER on the VoxSRC-22 evaluation set.Comment: 3 pages, 3 tables, VoxSRC202

    Dual-Polarized Communication Rectenna Array for Simultaneous Wireless Information and Power Transmission

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    A dual-polarized communication rectenna array with high isolation and low cross polarization for simultaneous wireless information and power transmission (SWIPT) is presented. It consists of a 2 × 2 element receiving antenna array and a high efficiency rectifier based on voltage doubler topology. The receiving element is corner-fed to achieve high isolation of more than 20 dB between the dual-polarized ports, which guarantees low mutual interference between the communication and the rectifying ports. To receive enough electromagnetic (EM) wave for rectifying and meanwhile meet the communication sensitivity, this 2 × 2 array uses its 2 × 2 vertical polarization ports and 1 × 2 horizontal polarization ports for power rectifying, and the rest 1 × 2 horizontal polarization ports for communication. For the communication port, the measured gain is 10.9 dBi and the cross polarization is less than -20 dB. The performance of the whole communication rectenna array has been measured, where a 2 × 4 circularly-polarized array with a gain of 17.5 dBi, settled 1 meter away is used as the transmitter. Measured results show that the system achieves a peak microwave - direct circuit (mw-dc) conversion efficiency of 74.9 % for the CW signal, and 67 % for the QPSK signal with 10 MHz channel bandwidth on the load of 345 Ω at 2.58 GHz operating frequency
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