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Effects of surface morphology on tribological properties of Arapaima gigas scales

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Friction 2024年第7期12卷 1469-1482页

作者： Shuaijun ZHANG Pengpeng BAI Xiangli wen Chengwei wen hui CAO Wanyou YANG Yu TIAN State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Bionic Engineering(Ministry of Education China)Jilin UniversityChangchun 130022China

The remarkable mechanical adaptability of arapaima(Arapaima gigas)scales has made them an important subject of ***,no research has been conducted into their tribological properties,which are crucial for the protectability and flexibility of *** this study,by combining morphological characterizations,friction experiments,and theoretical analyses,the relationship between the surface morphology and tribological properties of arapaima scales is *** results indicate that arapaima scales exhibit varying surface morphologies in different *** specifically,the exposed regions of scales feature grooves and a circulus,whereas the covered regions exhibit *** specific surface morphology of arapaima scales produces varying tribological properties across different regions and sliding *** unique tribological properties of arapaima scales influence the forces received from predator attacks and neighboring scales,directly influencing the arapaima’s protective *** study provides new insights into the mechanisms of natural flexible dermal armors,and it has potential applications in personal protective systems.

关键词： arapaima scales surface morphology tribological properties protectability

Mechanistic study of ozonation of p-nitrophenol in aqueous solution

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Journal of Environmental Sciences 2005年第6期17卷 926-929页

作者： SHI hui-xiang XU Xian-wen WANG Da-hui WANG Qi-da Department of Environmental Engineering Zhejiang University Hangzhou 310027 China Environmental Engineering Technology Evaluation Center of Zhejiang Province Hangzhou 310012 China Hangzhou Harmony Trade Go. Ltd Hangzhou310009 China

Ozonlysis in the treatment of p-nitrophenol solution was studied in this paper. The results indicated that the decomposition of pnitrophenol was accelerated as the gas flow rate or pH value increased. When gaseous ozone concentration was 20.11 mg/L and pH was 3, after 24 m in reaction, the removal rate of p-nitrophenol reached 73.04%, 86. 11%, 91.71% and 95% at the gas flow rate of 32, 40, 48 and 56 ml/min respectively. And when pH was 3, 4, 5, 6, the decomposition rate was 66.38%, 82.09%, 90.46%, 97.50% after a 20 min reaction respectively. It was mainly O3 molecule that took part in the decomposition when pH was 3. The main intermediates during the decomposition include catechol, o-benzoquinone, hydroquinone, p-benzoquinone, phenol, fumaric acid, maleic acid, oxalic acid and formic acid. The decomposition mechanism of p-nitrophenol was also discussed.

关键词： ozonation p-nitrophenol decomposition mechanism

Pressure Dependence of the Orientational Ordering in Solid C_(60):the Statistical Theory

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Chinese Physics Letters 1996年第5期13卷 386-389页

作者： LIU Ying SUN hui-ling HUA wen-shen Department of Physics Hebei Normal University Shijiazhuang 050016 department of Fundamental Courses Ordnance Engineering CollegeShijiazhuang 050003

Experiments on the pressure dependence of the orientational ordering in solid C_(60) suggest that,the critical temperature increases with the increase of *** paper has successfully explained this phenomenon from the v... 详细信息

关键词： theory. explained critical

Characterization of W80Cu20 alloy sheet prepared by hot-rolling

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Rare Metals 2013年第6期32卷 569-573页

作者： Hu-Ping Guo wen-Ge Chen hui Zhang School of Materials Science and Engineering Xi'an University of Technology

Multi-pass hot-rolling technique was used to fabricate W80Cu20 alloy,and its properties were characterized in this *** show that the W-Cu alloy sheets with a thickness of 0.5 mm and a relative density of99.87%can be successfully made using this new technique at 800℃.In hot-rolling process,Cu phases are closely surrounded by W particles under the rolling stress to form a network microstructure,thus making significant increase in electrical and thermal conductivity up to53.00%and 24.44%,*** and longitudinal hardness of the W–Cu sheets significantly increase due to the enhanced densification and deformation *** to that of the raw materials,three fracture types were observed in the hot-rolled materials,i.e.,ductile fracture of Cu binding phases,trans-granular fracture of W phases,and W–W interfacial fracture.

关键词： Hot-rolling W-Cu alloy Properties Fracture morphology Sheet

Electrodeposition of Ni–Co alloy films onto titanium substrate

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Rare Metals 2014年第4期33卷 442-447页

作者： Yu-Fang Yang Zhao-hui wen Qiang-Guo Li Department of Chemistry and Life Science Xiangnan University Library Xiangnan University

Binary bright Ni-Co alloy films were electro- deposited on titanium in the chloride-sulfate electrolytes. The influences of Co2＋ concentration, current density, and temperature on the Ni-Co alloy films electrodeposition were investigated. The films were analyzed by scanning electron microscope （SEM）, energy dispersive spectros- copy （EDS）, and X-ray diffraction （XRD）. Cathodic polarization for Ni-Co codeposition was performed on Ti working electrodes. With the increase of Co2＋ concentra- tion, the Ni content in the films decreases and the current efficiency increases slightly. The Ni content increases with the increase of temperature, while it decreases with the increase of current density to a minimum and then increases. The cathodic reduction peak potential is mea- sured to be -1.34 V. Anomalous deposition is found to occur in the Ni-Co codeposition. The SEM of Ni-Co alloy films shows that hydroxide particles are not present on the surface and fine grain, compact, smooth, and bright Ni--Co alloy films are obtained. The XRD result indicates that the deposited Ni-Co alloy film is Ni-solid solution with a face- centered cubic in structure.

关键词： Electrodeposition Ni-Co alloy Films Titanium substrate

EXPERI MENTAL INVESTIGATION INTO HOT WATER SLOT JETS WITH NEGATIVELY BUOYANCYIN CROSS FLOW

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Journal of Hydrodynamics 2005年第4期17卷 412-417页

作者： YANG Zhong-hua HUAI wen-xin DAI hui-chao State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan 430072 China

An experiment was conducted to examine the near-field behavior of negatively buoyant planar jets in flowing environment. Hot water jet was projected downwards at dif fercnt angles from a slot into a uniform cross flow. Micro Acoustic Doppler Velocimeter （Micro ADV） system is used to measure the velocity and turbulent fluxes of Reynolds stresses. The whole field temperatures were measured with fast response thermocouples. Pure jets experiments were made also to study the effect of buoyancy in negatively buoyant jets. It is found that the influenced area of hot jets is larger than which of pure jets when the jet angle is 90° and the influenced area of hot jets is smaller than which of pure jets when the jet angle is 45°. The difference is not obvious at 60° angle jets. This means that the rising of temperature has effect not only on negatively buoyancy, but also on the intensity of turbulence. The contrast of these two influences dominates the trend of jet flow.

关键词： negatively buoyant planar jets Micro Acoustic Doppler Velocimeter (Micro ADV) Reynolds stresses

Rainbow and Monochromatic Vertex-connection of Random Graphs

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Acta Mathematicae Applicatae Sinica 2022年第4期38卷 966-972页

作者： wen-jing LI hui JIANG Jia-bei HE School of Mathematics and Statistics North China University ofWater Resources and Electric PowerZhengzhou 450046China School of Mathematics Hefei University of TechnologyHefei 230000China

A vertex-colored path P is rainbow if its internal vertices have distinct colors;whereas P is monochromatic if its internal vertices are colored the *** a vertex-colored connected graph G,the rainbow vertex-connection number rvc(G)is the minimum number of colors used such that there is a rainbow path joining any two vertices of G;whereas the monochromatic vertex-connection number mvc(G)is the maximum number of colors used such that any two vertices of G are connected by a monochromatic *** two opposite concepts are the vertex-versions of rainbow connection number rc(G)and monochromatic connection number mc(G)*** study on rc(G)and mc(G)of random graphs drew much attention,and there are few results on the rainbow and monochromatic vertex-connection *** this paper,we consider these two vertex-connection numbers of random graphs and establish sharp threshold functions for them,respectively.

关键词： graph coloring rainbow vertex-connection number monochromatic vertex-connection number random graphs threshold function

Optimal bundles for sponsored search auctions via bracketing scheme

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Frontiers of Computer Science 2019年第2期13卷 333-342页

作者： Zheng-Dong XIA Tian-Ming BU wen-hui GONG Shanghai Key Laboratory of Trustworthy Computing East China Normal University Shanghai 200233 China

Sponsored search auction has been recently studied and auctioneer's revenue is an important consideration in probabilistic single-item second-price auctions. Some papers have analyzed the revenue maximization problem on different methods to bundle contexts. In this paper, we propose a more flexible and natural method which is called the bracketing method. We prove that finding a bracketing scheme that maximizes the auctioneer's revenue is strongly NP-hard. Then, a heuristic algorithm is given. Experiments on three test cases show that the revenue of the optimal bracketing scheme is very close to the optimal revenue without any bundling constraint, and the heuristic algorithm performs very well. Finally, we consider a simpler model that for each row in the valuation matrix, the non-zero cells have the same value. We prove that the revenue maximization problem with Kanonymous signaling scheme and cardinality constrained signaling scheme in this simpler model are both NP-hard.

关键词： sponsored search auction revenue maximization bracketing scheme NP-hardness

Comparison of growth and nutrient uptake capacities of three dominant species of Qinhuangdao green tides

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Acta Oceanologica Sinica 2023年第4期42卷 114-123页

作者： Hongbin Han Ruobing wen hui Wang Sheng Zhao North China Sea Ecological Center of the Ministry of Natural Resources Qingdao 266033China Key Laboratory of Ecological Prewarning Protection and Restoration of Bohai SeaMinistry of Natural ResourcesQingdao 266033China

Since 2015, green tides have been blooming in offshore waters of Qinhuangdao, with serious impacts on the local ecological environment and tourism. Ulva australis, Bryopsis plumosa, and U. prolifera are the dominant species of Qinhuangdao green tides, following a sequential succession pattern. Ulva prolifera is the dominant species,with the highest biomass and the greatest influence on the local ecological environment. To study the reason of green tide dominant species succession and U. profilera became the dominant species with the largest biomass,we compared and analyzed the growth and nutrient uptake capacity of the three algae. The results showed that temperature significantly affects the growth of the three species. Within the temperature range of the experimental setup, the optimum temperature for the growth of U. australis, B. plumosa and U. profilera is10℃, 15℃, and 20–25℃, respectively. Combined with the temperature variation trend during green tide bloom development, we believe that temperature is the key environmental factor for the succession of the dominant species. Ulva prolifera has a higher growth rate than U. australis and B. plumosa under the same nitrate,ammonium, and phosphate levels. Significant differences in the maximum absorption rate(R_(max)) and R_(max)/Ks(the relationship between uptake rate and substrate concentration) values indicated that U. prolifera had an apparent competitive advantage over U. australis and B. plumosa regarding nutrient uptake. Therefore, the strong growth and nutrient uptake capacities of U. prolifera might be the main reason for becoming the dominant species with the largest biomass in Qinhuangdao green tides.

关键词： growth nutrient uptake dominant specie green tide Qinhuangdao