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In situ study of the mechanical properties of airborne haze particles

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Science China(Technological Sciences) 2015年第12期58卷 2046-2051页

作者： DING MingShuai HAN WeiZhong LI ju.ma Evan SHAN ZhiWei Center for Advancing materials Performance from the Nanoscale (CAMP-Nano) and Hysitron Applied Research Center in China (HARCC) State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University Department of Nuclear Science and Engineering and Department of materials Science and Engineering Massachusetts Institute of Technology Department of materials Science and Engineering Johns Hopkins University

Particulate pollution has raised serious concerns regarding its potential impacts on human health in developing countries. However, much less attention has been paid to the threat of haze particles to machinery and industry. By employing a state-of-the-art in situ scanning electron microscope compression testing technique, we demonstrate that iron-rich and fly ash haze particles, which account for nearly 70% of the total micron-sized spherical haze particles, are strong enough to generate abrasive damage to most engineering alloys, and therefore can generate significant scratch damage to moving contacting surfaces in high precision machineries. Our finding calls for preventive measures to protect against haze related threat.

关键词： haze particle hardness abrasive damage precision industry

Reverse Analysis Method and Process for Improving malware Detection Based on XAI Model

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Computers, materials & Continua 2024年第12期81卷 4485-4502页

作者： Ki-Pyoung ma Dong-ju.Ryu Sang-Joon Lee Security Team Doosan Corp.Seoul04563Republic of Korea Btress Corp. Hanam-SiGyeonggi-Do12902Republic of Korea School of Business Administration Chonnam National UniversityGwangju61186Republic of Korea

With the advancements in artificial intelligence(AI)technology,attackers are increasingly using sophisticated techniques,including *** Detection&Response(EDR)is a system that detects and responds to strange activities or security threats occurring on computers or endpoint devices within an *** traditional antivirus software,EDR is more about responding to a threat after it has already occurred than blocking *** study aims to overcome challenges in security control,such as increased log size,emerging security threats,and technical demands faced by control *** studies have focused on AI detection models,emphasizing detection rates and model ***,the underlying reasons behind the detection results were often insufficiently understood,leading to varying outcomes based on the learning ***,the presence of both structured or unstructured logs,the growth in new security threats,and increasing technical disparities among control staff members pose further challenges for effective security *** study proposed to improve the problems of the existing EDR system and overcome the limitations of security *** study analyzed data during the preprocessing stage to identify potential threat factors that influence the detection process and its ***,eleven commonly-used machine learning(ML)models for malware detection in XAI were tested,with the five models showing the highest performance selected for further *** AI(XAI)techniques are employed to assess the impact of preprocessing on the learning process *** ensure objectivity and versatility in the analysis,five widely recognized datasets were ***,eleven commonly-used machine learning models for malware detection in XAI were tested with the five models showing the highest performance selected for further *** results indicate that eXtreme Gradient Boosting(XGBoost)model outperformed

关键词： Endpoint detection&response(EDR) explainable AI(XAI) SHapley Additive exPlanations(SHAP) reverse XAI machine learning(ML)

Distributions of dimethylsulfide in the Bohai Sea and Yellow Sea of China

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Journal of Environmental Sciences 2003年第6期15卷 762-767页

作者： HU Min TANG Xiao-yan LI Jin-long ma Qi-ju State Joint Key Laboratory of Environmental Simulation and Pollution Control Center for Environmental Sciences Peking UniversityBeijing 100871China.

Dimethylsulfide(DMS) measurements in the surface seawater of China eastern coastline were conducted during march 9—10, 1993 in Bohai Sea along the cruise from Dalian to Tianjin and during September 24—25, 1994 in Yellow Sea along the cruise from Shanghai to Qingdao. On the cruise in Bohai Sea DMS concentrations varied from 0.11 to 2.63 nmol/L with an average of 1.31 nmol/L, while DMS flux was estimated to be 0.85 μmol/(m 2·d) with the range of 0.04—3.12 μmol/(m 2·d). On the cruise in Yellow Sea DMS concentrations varied from 0.95 to 7.48 nmol/L with an average of 2.89 nmol/L, and DMS flux was estimated to be 7.94 μmol/(m 2·d) with the range of 0.11—18.88 μmol/(m 2·d). Variations in DMS concentrations along the latitude in Yellow Sea were observed larger than those along the longitude in Bohai Sea. DMS concentrations and fluxes had a similar spatial trend both in Bohai Sea and Yellow Sea with the correlation coefficients of 0.75 and 0.64, respectively.

关键词： dimethylsulfide sea-to-air flux China Bohai Sea China Yellow Sea

Theoretical Calculations of Thermal Broadenings and Transition Probabilities of R, R＇ and B Line-Groups for Ruby

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Communications in Theoretical Physics 2001年第12期36卷 723-728页

作者： ma Dong-Ping LIU Yan-Yun CHEN ju.Rong Department of Applied Physics Sichuan University Chengdu 610065 China International Centre for materials Physics The Chinese Academy of Sciences Shenyang 110015 China Department of Applied Physics Sichuan University Chengdu 610065 China Department of Applied Physics Sichuan University Chengdu 610065 China

On the basis of the unified calculation of the thermal shifts of R1 line, R2 line and ground-state-splitting transition probabilities of direct and Raman processes have theoretically been calculated. The thermal broadenings of R,The theoretically predicted transition probabilities are in good agreement with the experimental *** numbers: ***, ***, ***, 63.20.

关键词： crystal fields, electron-phonon interaction, thermal broadening, transition probability, direct and Raman processes

Circulation and Heat Flux along the Western Boundary of the North Pacific

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Journal of Ocean University of China 2020年第1期19卷 1-12页

作者： ju.Xia ma Chao XIONG Xueju. GUO Yanliang and YU Long College of Ocean and Atmosphere Sciences Ocean University of ChinaQingdao 266100China The First Institute of Oceanography MNRQingdao 266061China Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and TechnologyQingdao 266061China Laboratory for Ocean and Climate Dynamics Pilot National Laboratory for Marine Science and TechnologyQingdao 266100China

On the basis of the conductivity temperature depth(CTD)observation data off the coast of the Philippines(7.5°–18°N,130°E–the east coast of the Philippines)in the fall of 2005,the water mass distribution,geostrophic flow field,and heat budget are *** water masses are present:the North Pacific Tropical Surface Water,the North Pacific Sub-surface Water,the North Pacific Intermediate Water,and the Antarctic Intermediate Water(AAIW).The previous three corresponded with the North Equatorial Current(NEC),the Kuroshio Current(KC),and the Mindanao Current(MC),*** is the source of the Mindanao *** mass transport of NEC,KC,and MC is 58.7,15,and 27.95Sv,respectively(relative to 1500db).NEC can be balanced by the transport across the whole transect 18°N(31.81 Sv)and 7.5°N(26.11 Sv)but not simply by KC and *** calculation is used to study the heat *** sum,1.45PW heat is transported outwards the observed region,which is much more than that released from the ocean to the air at the surface(0.05PW).The net heat lost decreased the water temperature by 0.75℃each month on average,and the trend agreed well with the SST ***,the heat transported by the currents is mainly completed in the upper 500 m.

关键词： North Pacific western boundary currents water mass circulation heat flux

Characterization of YSZ Ceramic Nanopowders Synthesized at Different Temperatures via Polyacrylamide Gel Method

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Journal of Wuhan University of Technology(materials Science) 2020年第3期35卷 528-534页

作者： LIU Ting CHEN Weidong ju.Hongmin YAN Shufang ma Wen School of materials Science and Engineering Inner Mongolia University of TechnologyHohhot 010051China Inner Mongolia Key Laboratory of Thin Film and Coatings Hohhot 010051China

Tetragonal zirconia (T-ZrO2) ceramic nanopowders stabilized with 3 mol% Y2O3 were synthesized via polyacrylamide gel method, using ZrOCl2?8H2O and Y(NO3)3?6H2O as raw materials. The effect of temperature on phase composition and morphology of YSZ nanopowders and sintering behavior of YSZ ceramics was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Vickers hardness tester. The aging-resistance of YSZ ceramics was measured by means of aging experiments. The results demonstrated that the phase composition of YSZ ceramic nanopowders had no obvious change and it was composed of T-ZrO2. Particle size of well-dispersed YSZ ceramic nanopowders increased from 17 to 35 nm with increasing calcining temperature from 600 to 800 ℃. There was noticeable negative correlation between calcining temperature and the relative density of YSZ ceramic at the same sintering temperature. The aging experiments showed that water vapor facilitated tetragonal to monoclinic phase transformation, and the sample that had smaller grain size exhibited better aging-resistance. It can be concluded that when the calcining temperature is 600 ℃ and sintering temperature is 1550 ℃, the relative density and hardness of YSZ ceramic arrive at the peak of 96.64% and 11.135 GPa respectively, and it has less microcracks and excellent aging-resistance.

关键词： YSZ nanopowders polyacrylamide gel method sintering behavior aging-resistance grain size

Multi-scale analyses of phase transformation mechanisms and hardness in linear friction welded Ti17(a+β)/Ti17(β)dissimilar titanium alloy joint

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Chinese Journal of Aeronautics 2024年第1期37卷 312-324页

作者： Zhenguo GUO Tieju. ma Xiawei YANG ju.LI Wenya LI Achilles VAIRIS State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi’an 710072China Aeronautical Key Laboratory for Welding and Joining Technologies AVIC Manufacturing Technology InstituteBeijing 100024China Mechanical Engineering Department University of West AtticaAthens 12241Greece

The Ti17(a+β)-Ti17(β)dual alloy-dual property blisk produced using Linear Friction Welding(LFW)is considered as high-performance component in advanced ***,up to now,microstructure evolution and relationship between microstructure and micro mechanical properties of LFWed Ti17(a+β)/Ti17(β)dissimilar joint have not been thoroughly *** this work,complex analyses of the phase transformation mechanisms of the joint are conducted,and phase transformations in individual zones are correlated to their microhardness and *** reveal that a dissolution occurs under high temperatures encountered during LFW,which reduces microhardness of the joint to that of Ti17(a+β)and Ti17(β).In ThermoMechanically Affected Zone of Ti17(a+β)(TmaZ-(a+β))side joint,a large number of nanocrystalline a phases form with different *** microstructure strengthens significantly by fine grains which balances partial softening effect of a dissolution,and increases nanohardness of a phase and microhardness of TmaZ-(a+β).Superlattice metastableβphase precipitates from metastableβin Weld Zone(WZ)during quick cooling following welding,because of short-range diffusion migration of solute atoms,especiallyβstabilizing elements Mo and *** precipitation of the superlattice metastableβphase results in precipitation strengthening,which in turn increases nanohardness of metastableβand microhardness in WZ.

关键词： Linear friction welding Ti17 titanium alloy Phase transformation Microhardness Nanohardness

In situ growth process of Mg-Fe layered double hydroxide conversion film on MgCa alloy

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Journal of magnesium and Alloys 2021年第3期9卷 1019-1027页

作者： ju. Chen ju.Feng Lei Yan Huan Li Changqi Xiong Sude ma Key Laboratory of Fluid and Power machinery of Ministry of Education School of Materials Science and EngineeringXihua UniversityChengdu 610039China

In this study,an environment-friendly layered double hydroxide(LDH)film has been deposited on Mg Ca alloy by a two-step *** improve the chemical conversion technique and control the film properties,batch studies have been carried out to address various process parameters such as pH value,treatment temperature and immersion *** chemical composition was determined by X-ray diffractometry and energy dispersive X-ray *** morphology was characterized by scanning electron *** corrosion resistance of the samples with various films was compared by polarization curves and immersion *** is found that the transformation duration of Mg-Fe LDH is *** high pH value and temperature has harmful effect on the purity of the film *** corrosion resistance of the films formed at low value of pH or high temperature or short treatment time is *** optimum process is as follows:the sample is first immersed in the solution containing Fe^(3+)/HCO_(3)^-/CO_(3)^(2-)with a pH value of 5 at a temperature of 55℃for 1 h to form a precursor film,and then this precursor film is immersed into the solution containing Fe^(3+)/HCO_(3)^-/CO_(3)^(2-)with a pH of 11 at 55℃for 24 h to obtain the Mg-Fe LDH conversion film.

关键词： magnesium alloy Layered double hydroxide Film Corrosion Parameter optimization

The Dynamical Effects of a Large-Scale Ordered magnetic Field on Slim Disks

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Chinese Physics Letters 2013年第5期30卷 195-197页

作者： PING Chong ma Ren-Yi LU ju.Fu Department of Astronomy and Institute of Theoretical Physics and Astrophysics Xiamen UniversityXiamen 361005

The dynamics of slim disk under the influence of a large-scale ordered magnetic field is *** global solutions show that the radial velocity increases and the disk temperature decreases with enhancing magnetic *** fraction of mass loss becomes smaller when the accretion rate is *** ratio of the jet kinetic power to disk luminosity is less than 0.1,which indirectly supports the argument that radio-loud narrow-line Seyfert 1 galaxies share similarities with blazars.

关键词： galaxies field narrow