The MCrAlY coating has been potential candidate for the parts applied in friction and corrosion conditions, and CNTs (carbon nanotubes) are expected to improve the service performance of coatings owing to high lubrica...The MCrAlY coating has been potential candidate for the parts applied in friction and corrosion conditions, and CNTs (carbon nanotubes) are expected to improve the service performance of coatings owing to high lubrication and low chemical reactivity. In this work, a systematic investigation on the tribological and corrosion properties of CoCrAlYTaSiC-xCNTs coatings deposited by laser melting was analyzed. Results showed that the coatings had good-quality without typical metallurgical defects. The CNTs addition homogenized and refined the microstructure of coating, and also improved the tribological and corrosion properties. As the CNTs content changed from 0 to 4 wt%, the wear rate of coating decreased from 16.23 × 10^(-3) to 7.58 × 10^(-3) mg m^(−1), the jcorr of coating decreased from 4.13 × 10^(-4) to 1.23 × 10^(-4) A cm^(−2), and the Rct values increased from 12.69 to 25.07 Ω cm2.展开更多
High-altitude polycythemia(HAPC)is a prevalent chronic condition affecting individuals at high altitudes,including both highland and plains populations.This study,involving 2248 participants,explored genetic susceptib...High-altitude polycythemia(HAPC)is a prevalent chronic condition affecting individuals at high altitudes,including both highland and plains populations.This study,involving 2248 participants,explored genetic susceptibility to HAPC among ethnic groups,with 898 HAPC patients(450 Han,448 Tibetan).The Genome-wide Association Study,encompassing 198 cases(100 Han,98 Tibetan),identified eight Tibetan HAPC-susceptibility single-nucleotide polymorphisms and four in Han individuals.The common polymorphism locus rs7618658(SNX4,pcombine<5×10^(-8))was validated in both popula-tions.The investigation of Tibetan EPAS1 revealed the rs1374749 locus,along with linked loci,as a potential prevalence factor for HAPC.The GGTAC haplotype containing this locus emerged as a Protect haplotype for HAPC(p=2.461×10^(-12),OR=0.344).Enrichment analysis revealed that Tibetans exhibited susceptibility in oxygen-sensing pathways,such as EPAS1,associated with phenotypes like hemoglobin and platelets.In contrast,Han Chinese showed significant sensitivity in cell differentiation and angiogenesis,closely linked to hemoglobin,hematocrit,and platelets.展开更多
Following the popularity of digital video application,video copying and dissemination have become very easy;however,this makes video hacking and piracy a potential threat in video communication.Video watermarking tech...Following the popularity of digital video application,video copying and dissemination have become very easy;however,this makes video hacking and piracy a potential threat in video communication.Video watermarking technology can solve the problem of copyright protection,and thus,it has been extensively researched.The robustness of the video watermarking algorithm in the bitstream domain is poor,especially the anti-recompression ability,since the watermarked video may be compressed again before transmitting.Considering this,this paper proposes a video watermarking algorithm in the bitstream domain based on moving object detection.To increase the robustness of the watermarking scheme,the moving macroblocks that belong to the moving object in each P frame can be identified via the moving object detection algorithm.Then,watermark embedding in the moving macroblocks is performed using codeword substitution to ensure the consistency of the bitstream.Moving object detection and watermark embedding are independent and are both carried out in the bitstream domain by partially decoding the bitstream;this avoids the complete decoding and reconstruction of the video,making the method to be highly efficient.The simulation results confirm that the proposed method is robust against recompression and has little impact on the video visual quality and no influence on the bit rate.展开更多
Gas diffusion in the coal matrix plays a significant role in forecasting the production performance of coalbed methane(CBM)wells.To better understand methane diffusion behavior,a systematic study was performed on vari...Gas diffusion in the coal matrix plays a significant role in forecasting the production performance of coalbed methane(CBM)wells.To better understand methane diffusion behavior,a systematic study was performed on various rank coals with vitrinite reflectance(Ro,m)ranging from 0.46%to 2.79%.Multiple experiments,including coal petrographic analysis,field emission scanning electron microscopy(FESEM),low-temperature N2 adsorption/desorption,and mercury intrusion porosimetry(MIP),were conducted to quantitatively characterize the multiscale micro-nano pore system in different rank coals,which showed that the pore structure of coals exhibited a multimodal pore size and volume distribution.Isothermal adsorption-diffusion experiments using the volumetric method were also performed to understand the methane diffusion characteristics in the micro-nano pores of the coal reservoir.The applicability of the multiporous diffusion model is verified,and methane diffusion in the multi-scale pores of coal reservoirs exhibits the characteristics of early fast diffusion,transitional diffusion in the medium term,and slow diffusion in the later period.In addition,the factors affecting methane diffusion in coals were systematically analyzed,and gray relational analysis(GRA)was employed to analyze and identify the importance of these factors on methane diffusion.The results show the impact ranking of factors,in order from the most important to the least:particle size>moisture>surface area>pore volume>pressure>coal rank>temperature in all of three diffusion stages.These findings are helpful for forecasting production performance and enhancing the production efficiency of CBM.展开更多
文摘The MCrAlY coating has been potential candidate for the parts applied in friction and corrosion conditions, and CNTs (carbon nanotubes) are expected to improve the service performance of coatings owing to high lubrication and low chemical reactivity. In this work, a systematic investigation on the tribological and corrosion properties of CoCrAlYTaSiC-xCNTs coatings deposited by laser melting was analyzed. Results showed that the coatings had good-quality without typical metallurgical defects. The CNTs addition homogenized and refined the microstructure of coating, and also improved the tribological and corrosion properties. As the CNTs content changed from 0 to 4 wt%, the wear rate of coating decreased from 16.23 × 10^(-3) to 7.58 × 10^(-3) mg m^(−1), the jcorr of coating decreased from 4.13 × 10^(-4) to 1.23 × 10^(-4) A cm^(−2), and the Rct values increased from 12.69 to 25.07 Ω cm2.
基金National Key R&D Program of China(2023YFA1801200)National Science Foundation of China(32288101,32200536,82241023)+9 种基金The Science and Technology Department of Tibet(08080002)2019 School-level Cultivation Project of Tibet University(ZDTSJH19-08)Special Funds from the Central Finance to Support the Development of Local Universities(2018)No.54(2019)No.1-19(2020)No.79,(2021])No.1,(00060695/003)Special of the Disposal of the Science and Technology Department of Tibet Autonomous Region in 2023(18080280)Tibet Autonomous Region Natural Science Foundation Group Medical Assistance Project Plan(XZ2023ZR-ZY34(Z))Municipal Natural Science Foundation(joint)project(RKZ2023ZR-014(Z))Shanghai Municipal Science and Technology Major Project(2023SHZDZX02,2017SHZDZX01)CAMS Innovation Fund for Medical Sciences(2019-I2M-5-066).
文摘High-altitude polycythemia(HAPC)is a prevalent chronic condition affecting individuals at high altitudes,including both highland and plains populations.This study,involving 2248 participants,explored genetic susceptibility to HAPC among ethnic groups,with 898 HAPC patients(450 Han,448 Tibetan).The Genome-wide Association Study,encompassing 198 cases(100 Han,98 Tibetan),identified eight Tibetan HAPC-susceptibility single-nucleotide polymorphisms and four in Han individuals.The common polymorphism locus rs7618658(SNX4,pcombine<5×10^(-8))was validated in both popula-tions.The investigation of Tibetan EPAS1 revealed the rs1374749 locus,along with linked loci,as a potential prevalence factor for HAPC.The GGTAC haplotype containing this locus emerged as a Protect haplotype for HAPC(p=2.461×10^(-12),OR=0.344).Enrichment analysis revealed that Tibetans exhibited susceptibility in oxygen-sensing pathways,such as EPAS1,associated with phenotypes like hemoglobin and platelets.In contrast,Han Chinese showed significant sensitivity in cell differentiation and angiogenesis,closely linked to hemoglobin,hematocrit,and platelets.
基金supported by the National Natural Science Foundation of China(No.61702563)。
文摘Following the popularity of digital video application,video copying and dissemination have become very easy;however,this makes video hacking and piracy a potential threat in video communication.Video watermarking technology can solve the problem of copyright protection,and thus,it has been extensively researched.The robustness of the video watermarking algorithm in the bitstream domain is poor,especially the anti-recompression ability,since the watermarked video may be compressed again before transmitting.Considering this,this paper proposes a video watermarking algorithm in the bitstream domain based on moving object detection.To increase the robustness of the watermarking scheme,the moving macroblocks that belong to the moving object in each P frame can be identified via the moving object detection algorithm.Then,watermark embedding in the moving macroblocks is performed using codeword substitution to ensure the consistency of the bitstream.Moving object detection and watermark embedding are independent and are both carried out in the bitstream domain by partially decoding the bitstream;this avoids the complete decoding and reconstruction of the video,making the method to be highly efficient.The simulation results confirm that the proposed method is robust against recompression and has little impact on the video visual quality and no influence on the bit rate.
基金This research was funded by the National Natural Science Foundation of China(Grant Nos.41922016,41830427,and 41772160)the Fundamental Research Funds for the Central Universities(No.2652019264).
文摘Gas diffusion in the coal matrix plays a significant role in forecasting the production performance of coalbed methane(CBM)wells.To better understand methane diffusion behavior,a systematic study was performed on various rank coals with vitrinite reflectance(Ro,m)ranging from 0.46%to 2.79%.Multiple experiments,including coal petrographic analysis,field emission scanning electron microscopy(FESEM),low-temperature N2 adsorption/desorption,and mercury intrusion porosimetry(MIP),were conducted to quantitatively characterize the multiscale micro-nano pore system in different rank coals,which showed that the pore structure of coals exhibited a multimodal pore size and volume distribution.Isothermal adsorption-diffusion experiments using the volumetric method were also performed to understand the methane diffusion characteristics in the micro-nano pores of the coal reservoir.The applicability of the multiporous diffusion model is verified,and methane diffusion in the multi-scale pores of coal reservoirs exhibits the characteristics of early fast diffusion,transitional diffusion in the medium term,and slow diffusion in the later period.In addition,the factors affecting methane diffusion in coals were systematically analyzed,and gray relational analysis(GRA)was employed to analyze and identify the importance of these factors on methane diffusion.The results show the impact ranking of factors,in order from the most important to the least:particle size>moisture>surface area>pore volume>pressure>coal rank>temperature in all of three diffusion stages.These findings are helpful for forecasting production performance and enhancing the production efficiency of CBM.
