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China Communications 2021年第6期18卷 172-183页

作者： Zihan Li Zhaofeng ma International School Beijing University of Posts and TelecommunicationsBeijing 100876China School of Cyberspace Security Beijing University of Posts and TelecommunicationsBeijing100876China

With the in-depth application of new technologies such as big data in education fields,the storage and sharing model of student education records data still faces many challenges in terms of privacy protection and efficient *** this paper,we propose a data security storage and sharing scheme based on consortium blockchain,which is a credible search scheme without *** our scheme,the implementation of data security storage is using the blockchain and storage server *** detail,the smart contract provides protection for data keywords,the storage server stores data after data masking,and the blockchain ensures the traceability of query *** need for precise privacy data is achieved by constructing a *** techniques such as AES and RSA are used for encrypted storage of data,keywords,and digital *** analysis and performance evaluation shows that the availability,high efficiency,and privacy-preserving can be ***,this scheme has better robustness compared to other educational records data sharing models.

关键词： blockchain,big data,data transmission smart contract searchable encryption

Optimizing Electroless Plating of Ni-mo-P Coatings Toward Functional Ceramics

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Acta metallurgica Sinica(English Letters) 2020年第3期33卷 437-445页

作者： N.ma.Rosas-Laverde A.Pruna J.Cembrero m.Pascual J.Orozco-messana Department of materials and mechanical Engineering Universitat Politecnica de ValenciaValenciaSpain Department of materials Escuela Politecnica NacionalQuitoEcuador Center for Surface Science and Nanotechnology Polytechnic University of BucharestBucharestRomania Instituto de Tecnologia de materiales Universitat Politecnica de ValenciaValenciaSpain

Ni-mo-P coatings are obtained at the surface of ceramic substrate by electroless deposition using palladium as a surface *** influence of catalyst activation conditions on coatings’ properties was assessed by structural,morphological,electrical,mechanical measurements and adhesion strength by using X-ray diffraction,field emission scanning electron microscopy,atomic force microscopy,Hall effect and nanoindentation techniques,*** results indicated the formation of dense,continuous and uniform coatings consisting mainly of *** coatings obtained at 300℃for 12 h exhibited the best electrical properties,namely resistivity of 9.32 μΩ cm,smaller roughness(Ra 0.090 μm) and average mechanical *** adhesion tests showed a firm adherence of the Ni-mo-P coatings to the ceramic *** results of this study could offer an approach for obtaining conducting ceramic substrates in order to be employed in photovoltaic *** performance of demonstrative heterojunction solar cell obtained with such metallized ceramic is indicative of the high potential of the Ni-mo-P electroless coatings for functional ceramics.

关键词： Electroless plating Ni-mo-P Ceramic Solar cell

Screening and Characterization of Nitrite-Degrading Bacterial Isolates Using a Novel Culture medium

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Journal of Ocean University of China 2020年第1期19卷 241-248页

作者： ma Qingshan HE Zengguo School of medicine and Pharmacy Ocean University of ChinaQingdao 266003China marine Biomedical Research Institute of Qingdao Qingdao 266003China

In this study,a novel culture medium that simulates shrimp pond conditions was established to screen nitrite-degrading *** medium was supplemented with nitrite as a nitrogen source and shrimp feed as the major carbon source,to achieve the high nitrogen and low carbon nutritional status found in shrimp farming *** using this medium identified potent denitrifying Bacillus isolates,among which Bacillus subtilis m7-1 was considered best.m7-1 was able to completely degrade nitrite-N in 24 h without much consumption of dissolved *** denitrification activity took place in liquid cultures within a set of non-stringent ranges of pH(5.0–9.0),salinity(0–30)and temperature(25–35℃).The denitrifying enzyme gene was amplified,sequenced and further identified as nirS *** biosecurity assessments,m7-1 had no negative effects on shrimps at a dose of 106 cfu mL−1.m7-1 could therefore be used in aquaculture to reduce and control the nitrogen concentration,and to promote the development of sustainable and healthy culture systems.

关键词： aerobic denitrification nitrite screening culture medium Bacillus subtilis

Two-stage aging treatment to accelerate aging kinetics without impairing strength in B_4C/7A04Al composite

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Science China(Technological Sciences) 2024年第8期67卷 2485-2492页

作者： CHEN YunTao ma GuoNan ZHU ShiZe WANG Dong XIAO BoLv ma ZongYi Shi-Changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Centre of Excellence for Advanced materials Dongguan 523808China

Aging treatments are the key process to obtain satisfactory strength for 7xxxAl alloys and their composites. However, traditional single-stage(SS) aging is time-consuming to reach a peak strength condition. In this study, an efficient 120℃ + 160℃ two-stage(TS) aging treatment was proposed on a B_4C/7A04Al composite fabricated via powder metallurgy(Pm) technology, which could acquire similar peak-aging strength but only took about 15% of the time compared to traditional 120℃ SS aging. The evolution of precipitation during the TS aging was investigated, as well as those of the 7A04Al alloys for comparison. In the second stage aging process, the higher aging temperature accelerated the nucleation of η′ phases inside the grains and thus increased the density of precipitates. moreover, the short aging time limited the coarsening of precipitates and the broadening of precipitatefree zones. The above factors were beneficial for quickly obtaining satisfactory precipitation strengthening effects. The B_4C/7A04Al composite exhibited slower aging kinetics than the 7A04Al alloy in the TS aging. mg elements consumption by the chemical reaction between B impurities introduced by B_4C particles and the Al matrix was considered to potentially retard the aging kinetics of the B_4C/7A04Al composite. Nevertheless, the precipitation sequence was not affected.

关键词： aluminum matrix composites aging treatment powder metallurgy mechanical properties precipitation

X-ray multiple Diffraction Topographic Imaging Technique For Growth History Study of Habit modifying Impurity Doped Crystals

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Chemical Research in Chinese Universities 2004年第4期20卷 411-416页

作者： LAI X. ma C. K. J. Robert m. C. miller Institute of Particle Science and Engineering Department of Chemical Engineering University of LeedsInstitute of Particle Science and Engineering Department of Chemical Engineering University of LeedsInstitute of Particle Science and Engineering Department of Chemical Engineering University of LeedsCCLRC Daresbury Laboratory Daresbury Leeds LS2 9JT UKLeeds LS2 9JT UKLeeds LS2 9JT UKWarrington Cheshire WA4 4AD UK

A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symmetry and its spatial dependence in relation to lattice defects. This facility is used to examine, in a self-consistent manner, growth sector-dependant changes to both the crystallographic structure and the lattice defects associated with the action of habit-modifying additives in a number of representative crystal growth systems. In addition, the new instrument can be used to probe micro-crystallographic aspects(such as distortion to crystal symmetry) and relate these in a spatially resolved manner to the crystal defect structure in crystals doped with known habit modifiers.

关键词： X-ray diffraction X-ray multiple diffraction X-ray topography Habit modification Crystal growth Growth defects

Atmospheric extinction properties in Shenyang,China

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Particuology 2015年第1期13卷 120-126页

作者： Ningwei Liu Yanjun ma Jianzhong ma Yangfeng Wang Suying Yang Liguang Li Chinese Academy of meteorological Sciences Nanjing University of Information Science & Technology Institute of Atmospheric Environment China Meteorological Administration

Atmospheric visibility impairment due to human activities is becoming increasingly significant in metropolitan 8henyang, China. In this study, hourly data of relevant factors throughout the year 2010 in Shenyang were used to evaluate the local atmospheric extinction properties. The results show that the average coefficient of total extinction and aerosol single-scattering albedo in 2010 were 622.72 mm^-1 and 0.87, respectively, values that are characteristic of the ＂municipal pollution type＂. Visibility is most impaired during winter and especially in January. The coefficient of total extinction exhibits a single daily cycle with a maximum at 5-6 am and a minimum at 3 pm. The mean extinction contributions of the constituents, from high to low, were particle scattering （87.49%）, particle absorption, gas absorption, and gas scattering. The extinction contribution of gas molecules was little more than 4.5%, far smaller than that of particles. Scattering by particles was the main contributor to extinction, especially in the morning and around midnight.

关键词： Atmospheric visibility Extinction properties Extinction contributions Partide scattering

The role of oil futures intraday information on predicting US stock market volatility

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Journal of management Science and Engineering 2021年第1期6卷 64-74页

作者： Yusui Tang Xiao Xiao m.I.m.Wahab Feng ma School of Economics&management Southwest Jiaotong UniversityChengduChina Department of mechanical and Industrial Engineering Ryerson UniversityTorontoCanada

This study investigates the role of oil futures price information on forecasting the US stock market volatility using the HAR ***-sample results indicate that oil futures intraday information is helpful to increase the ***,compared to the benchmark model,the proposed models improve their predictive ability with the help of oil futures realized *** particular,the multivariate HAR model outperforms the univariate ***,considering the contemporaneous connection is useful to predict the US stock market ***,these findings are consistent across a variety of robust checks.

关键词： Volatility forecasting The US stock market Oil market volatility Realized volatility DCC model

A review of novel ternary nano-layered maX phases reinforced AZ91D magnesium composite

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Journal of magnesium and Alloys 2022年第6期10卷 1457-1475页

作者： Wantong Chen Wenbo Yu Chaosheng ma Guozheng ma Laiqi Zhang Haidou Wang Center of materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing 100044China National Key Lab for Remanufacturing Army Academy of Armored ForcesBeijing 100072China State Key Laboratory for Advanced metals and materials University of Science and Technology Beijing100083China

In recent decades, the demand for lightweight and high specific strength materials brings about the development of magnesium matrix composites. Different from some traditional binary ceramic particles, such as SiC, Al_(2)O_(3), the novel ternary nano-layered m_(n+1)AX_(n)(maX)phase carbide or nitride ceramics exhibit metal-like properties and self-lubricate capacity(where “m” is an early transition metal, “A” belongs to the group A element, “X” is C or/and N, and n = 1–3). Ti_(2)AlC, as the representative of the maX phase, was interestingly introduced into the magnesium matrix. Layered Ti_(2)AlC maX phased reinforced AZ91D magnesium composites manufactured through the stir casting exhibit sufficient deformation capacity due to unique deformation behaviors of maX, namely delamination and the formation of kinking band. Further,the Ti_(2)AlC-AZ91D composites exhibit a distinctive characteristic in strengthening mechanism, damping mechanism and tribological capacity due to the other special properties of maX phase, such as self-lubricated property. Accordingly, to give a comprehensive understanding, we overviewed the fabrication process, microstructural characterization, mechanical properties, damping property and tribological capacity on these composites. In order to understand the A-site effect in maX phase on the microstructure, we introduced another representative Ti_(3)SiC_(2)maX phase to explain the interfacial evolution. In addition, due to the high aspect ratio of maX, maX particles could be orientationally regulated in mg matrix by plastic deformation such as hot extrusion. Herein, we discussed the anisotropic mechanical and physical properties of the textured composites produced by hot extrusion. moreover, the potential applications and future development trends of maX phases reinforced magnesium matrix composites were also given and prospected.

关键词： Ternary maX phases magnesium composite Damping mechanical properties Anisotropic Tribological capacity

GA-BP Air Quality Evaluation method Based on Fuzzy Theory

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Computers, materials & Continua 2019年第1期58卷 215-227页

作者： ma Ning Jianhe Guan Pingzeng Liu Ziqing Zhang Gregory m.P.O’Hare China University of Geoscience Beijing100083China Shandong Agricultural University Taian271018China Shandong Vocational Institute of Fashion Technology Taian271000China University College Dublin(UCD) BelfieldDublin999014Ireland

With the rapid development of China’s economy,the scale of the city has been continuously expanding,industrial enterprises have been increasing,the discharge of multiple pollutants has reached the top of the world,and the environmental problems become more and more *** air pollution problem is particularly *** quality has become a daily concern for *** order to control air pollution,it is necessary to grasp the air quality situation in an all-round *** is necessary to evaluate air *** results of air quality evaluation can help people know more about air *** this paper,refers to previous research results and different evaluation methods,combined with artificial neural network,fuzzy theory,genetic algorithm,GA-BP hybrid algorithm based on fuzzy theory is proposed to evaluate air *** the same time,for the problem that the two-grade standard of air quality annual evaluation is not suitable for practical application,the four-grade standard for annual air quality evaluation has been proposed,and its practicality has been verified through *** setting contrast experiments and comparing the air quality evaluation model based on standard BP algorithm,it is proved that the fuzzy GA-BP evaluation model is better than the standard BP model,both in efficiency and accuracy.

关键词： Air quality evaluation fuzzy theory genetic algorithm BP neural network

Ultrathin and Flexible CNTs/mXene/Cellulose Nanofibrils Composite Paper for Electromagnetic Interference Shielding

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Nano-micro Letters 2019年第4期11卷 276-292页

作者： Wentao Cao Chang ma Shuo Tan mingguo ma Pengbo Wan Feng Chen Department of Orthopedics Shanghai Tenth People’s HospitalTongji University School of MedicineShanghai 200072People’s Republic of China Engineering Research Center of Forestry Biomass materials and Bioenergy Beijing Key Laboratory of Lignocellulosic ChemistryCollege of Materials Science and TechnologyBeijing Forestry UniversityBeijing 100083People’s Republic of China Center of Advanced Elastomer materials State Key Laboratory of Organic-Inorganic CompositesBeijing University of Chemical TechnologyBeijing 100029People’s Republic of China

As the rapid development of portable and wearable devices,different electromagnetic interference(EmI)shielding materials with high efficiency have been desired to eliminate the resulting radiation ***,limited EmI shielding materials are successfully used in practical applications,due to the heavy thickness and absence of sufficient strength or ***,an ultrathin and flexible carbon nanotubes/mXene/cellulose nanofibrils composite paper with gradient and sandwich structure is constructed for EmI shielding application via a facile alternating vacuum-assisted filtration *** composite paper exhibits outstanding mechanical properties with a tensile strength of 97.9±5.0 mPa and a fracture strain of 4.6±0.2%.Particularly,the paper shows a high electrical conductivity of 2506.6 S m?1 and EmI shielding effectiveness(EmI SE)of 38.4 dB due to the sandwich structure in improving EmI SE,and the gradient structure on regulating the contributions from reflection and *** strategy is of great significance in fabricating ultrathin and flexible composite paper for highly efficient EmI shielding performance and in broadening the practical applications of mXene-based composite materials.

关键词： mXene Carbon nanotubes Cellulose nanofibrils mechanical property Electromagnetic interference shielding