检索结果-南通市图书馆

microstructural tailoring,mechanical and thermal properties of SiC composites fabricated by selective laser sintering and reactive melt infiltration

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2023年第4期12卷 830-847页

作者： Xiao Chen Jie Yin Longzhi Huang sea.Hoon Lee Xuejan Liu Zhengren Huang State Key Lab of High Performance Ceramics and Superfine microstructures Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China College of materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049China Extreme materials Institute Korea Institute of Materials ScienceChangwon 51508Republic of Korea

Poor flowability of printable powders and long preparation cycles are the main challenges in the selective laser sintering(SLS)of chopped carbon fiber(C_(f))reinforced silicon carbide(SiC)composites with complex *** this study,we develop an efficient and novel processing route in the fabrication of lightweight SiC composites via the SLS of phenolic resin(PR)and Cr powders with the addition of a-SiC particles combined with the one-step reactive melt infiltration(RmI).The effects of a-SiC addition on the microstructural evolution of the C_(f)/SiC/PR printed bodies,C_(f)/SiC/C green bodies,and derived SiC composites were *** results indicate that the added a-SiC particles play an important role in enhancing the flowability of raw powders,reducing the *** the reliability of the C/SiC/C green bodies,and contributing to improving the microstructure homogeneity and mechanical properties of the SiC *** maximum density,flexural strength,and fracture toughness(Kic)of the SiC composites are 2.749±0.006 g·cm^(3),266±5 mPa,and 3.30±0.06 mPa-m,*** coefficient of thermal expansion(CTE,a)of the SiC composites is approximately 4.29×10^(-6)K^(-1)from room temperature(RT)to 900℃,and the thermal conductivity(x)is in the range of 80.15-92.48 W·m^(-1)·K^(-1)at *** high-temperature strength of the SiC composites increase to 287±18 mPa up to 1200℃.This study provides a novel as well as feasible tactic for the preparation of high-quality printable powders as well as lightweight,high-strength,and high-x SiC composites with complex structures by the SLS and RmI.

关键词： chopped carbon fiber(C_(f)) microstructural tailoring selective laser sintering(SLS) mechanical properties thermal properties

modern microbialites and their environmental signifi-cance,meiji reef atoll,Nansha (Spratly) Islands,South China sea

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2008年第4期51卷 608-617页

作者： SHEN JianWei1 & WANG Yue1,2 1 Department of marine Geology, South China sea.Institute of Oceanology Key Laboratory of marginal sea.Geology, South China sea.Institute of Oceanology and Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510301, China 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, China Department of marine Geology South China Sea Institute of Oceanology Guangzhou China Key Laboratory of marginal sea.Geology South China Sea Institute of Oceanology and Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate University of the Chinese Academy of Sciences Beijing China

meiji (mischief) coral atoll, in Nansha (Spratly) Islands, South China sea. consists of an annular reef rim surrounding a central lagoon. On the atoll rim there are either protuberant 'motu' (small coral patch reefs on the rim of atoll) islets or lower sandy cays that contain modern microbialite deposits on the corals in pinnacles and surrounding bottoms of the atoll. microbialites, including villiform, hairy, and thin spine growth forms, as well as gelatinous masses, mats and encrustation, developed on coral colonies and atoll rim sediments between 0 and 15 m deep-water settings. The microbialites were produced by natural populations of filamentous cyanobacteria and grew on (1) bulbous corals together with Acropora sp., (2) on massive colonies of Galaxea fascicularis, (3) on dead montipora digitata, and (4) on dead Acropora teres, some hairy microbialite growing around broken coral branches. This study demonstrates that microbial carbonates are developed in coral reefs of South China sea.and indicates that microbial processes may be important in the construction of modern reef systems. The results have significance in the determination of nature and composition in microorganisms implied in the formation ancient microbialites, and permit evaluation of the importance of microbial deposits in mo-dern coral reefs and of 'microbialites' in biogeochemical cycles of modern coral reef systems. The re-sults also provide evidence of modern analogues for ancient microbialites in shallow-water settings, and combine with sedimentological studies of ancient microbialites to understand their controls.

关键词： microbialite meiji reef Nansha Island South China sea

Arctic sea.ice extent: No record minimum in 2023 or recent years

在线全文

学校读者我要写书评

暂无评论

Atmospheric and Oceanic Science Letters 2025年第1期18卷 52-55页

作者： Ola m.Johannessen Tor I.Olaussen Nansen Scientific Society BergenNorway Nansen Environmental and Remote Sensing Center BergenNorway

Arctic sea.ice extent reaches its minimum each year in September. On 11 September 2023 the minimum was 4.969 million square kilometers(***^(2)). This was not a record low, which occurred in 2012, when the minimum was 4.175 ***^(2), 0.794 ***^(2) less than the minimum in 2023. However, the ice extent had decreased by 0.432 ***^(2) compared with 2022. Nevertheless, the summer melting in 2023 was remarkably less than expected when considering the strong heat waves in the atmosphere and ocean, with record temperatures set around the world. In general, there is a high correlation between the long-term decrease in sea.ice extent and the increasing CO_(2) in the atmosphere, where the increase of CO_(2) in recent decades explains about 80% of the decrease in sea.ice in September, while the remainder is caused by natural variability.

关键词： sea.ice Arctic minimum ice Climate

Assessment of coral bleaching using symbiotic zooxanthellae density and satellite remote sensing data in the Nansha Islands,South China sea

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2011年第10期56卷 1031-1037页

作者： LI Shu,YU KeFu,CHEN TianRan,SHI Qi & ZHANG HuiLing CAS Key Laboratory of marginal sea.Geology,South China sea.Institute of Oceanology,Chinese Academy of Sciences Guangzhou 510301,China CAS Key Laboratory of marginal sea.Geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China

Coral bleaching,characterized by a significant loss of symbiotic zooxanthellae,is the primary cause of mass coral mortality and reef degradation throughout the *** characteristics,processes,and resistance of corals to bleaching varies significantly and is dependent on environmental *** documented a mass coral bleaching event in June 2007 at the meiji and Zhubi Reefs,Nansha Islands (NS),South China sea.using ecological surveys and measurement of coral zooxanthellae density and sea.surface temperatures (SST).more than 35 species of corals (between 0-20 m in depth) were *** bleached corals accounted for 15.6% of total corals in the investigated *** branching corals Pocillopora and Acropora were the most vulnerable species whereas the massive corals Porites and Favia were more tolerant of the high ***,we found no evidence of bleaching in Agariciidae corals suggesting that this family is resistant to thermal *** bleached corals had lost 72%-90% of their symbiotic ***,corals that had no visual signs of bleaching had also lost 31%-53% of their zooxanthellae suggesting that most corals were experiencing the early stage of *** monthly mean SST during June 2007 was 30.8°C,the highest since *** on measurements of SST and the Hotspots and DHW data (NOAA),we conclude that it the extremely high SSTs triggered this coral bleaching *** results suggest that the previously accepted temperature thresholds used to predict coral bleaching based on satellite data are likely to underestimate the extent and intensity of coral bleaching,at least in the NS.

关键词：珊瑚礁南沙群岛中国南海卫星遥感数据漂白黄藻密度共生

Below-ground growth characteristics of 13-year-old Pinus densiflora on different contour conditions in a post-fire plantation in Samcheuk,Korea

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Resea.ch 2017年第5期28卷 1007-1018页

作者： Do-Hyun Kim Sung-Jun Na sea.Hyun Kim Ewane Basil Ewane Dae-Bong Kang Do-Hyung Lee Department of Forest Resources Yeungnam University Department of Forest Genetic Resources National Institute of Forest Science

We estimated the growth volume of artificially reforested Pinus densiflora in a post-fire area on three different contour conditions by comparing and analyzing the vertical and horizontal distributions of below-ground roots on each contour. The main roots at the south-facing slope (SS) developed in a long and straight form, and those on the north-facing slope (NS) in a twisted form. The side roots developed more than the main roots on the Ridge. The depth of taproots decreased in the following order: SS > NS > Ridge. The roots on the SS developed in a pile-form root structure whereas those in the Ridge and NS developed concentrically near the root collar. The amount of root development decreased in the following order: SS > NS > Ridge. The ratio of fine roots from the whole-root development decreased in the following order: Ridge > SS > NS. These results can guide considerations of growth differences according to the planting contour conditions for future establishment of P. densiflora artificial plantations.

关键词： Pinus densiflora Growth characteristics Contour conditions Post-fire plantation Wildfire Restoration Soil depth

Cross-scale microstructure design of precursor-derived SiC-AlN nanoceramic composites hybrid with ex-situ ZrB_(2)

在线全文

学校读者我要写书评

暂无评论

Advanced Powder Materials

Advanced Powder materials 2023年第1期2卷 35-42页

作者： Aidong Xia Buhao Zhang Jie Yin Xiao Chen sea.Hoon Lee Xuejian Liu Zhengren Huang State Key Laboratory of High Performance Ceramics and Superfine microstructures Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Ningbo Institute of materials Technology and Engineering Chinese Academy of SciencesNingbo 315201China College of materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049China Ceramic materials Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

ZrB_(2)/SiC–AlN nanoceramic composites were densified at 1950℃ by hot pressing using an organic-precursorderived SiC and commercially available AlN and ZrB_(2).A cross-scale microstructure was constructed by distributing the ZrB_(2) secondary phase(~421 nm)within the SiC–AlN solid solution *** substructure of the SiC–AlN matrix was agglomerated by nanograins with an average size of only 62 ***_(2) connected around the majority of pores within the SiC–AlN matrix and contributed to the formation of numerous weak interfacial bonding,resulting in improved strength and *** highest flexural strength and fracture toughness of 579±52 mPa and 6.7±0.1 mPa m^(1/2) were obtained from a 10 wt%-ZrB2/SiC–AlN sample,*** high concentration of grain boundaries of the ZrB2/SiC–AlN nanoceramic composites resulted in heat insulation *** thermal diffusivity and conductivity were 3.6 mm^(2)·s^(-1) and 14.3 W⋅(m·K)^(-1) at 1400℃,respectively,while the electrical resistivity was 3.9×10^(3)Ω·cm for the 10 wt%-ZrB_(2)/SiC–AlN sample.

关键词： Nanoceramic composites Precursor-derived ceramics SiC-AlN solid Solution mechanical properties Thermal and electrical properties

CHGS method for numerical forecasting of typhoon waves-Ⅰ. Spectrum of waves in growing phase

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 1990年第3期9卷 343-352页

作者： Sui Shifeng South China sea.Institute of Oceanology, Academia Sinica, Guangzhou, China

Owing to the fact that the wind speed and direction of typhoon vary rapidly with time and space in typhoon fetch; the nearer to the typhoon eye the greater the wind velocity, and the shorter the wind fetch the smaller the wind time,as a result,the more difficult for the wind wave to fully grow. *** typhoon wave numerical calculation it is impossible to use the model for a fully grown wave spectrum. Lately, the author et at. presented a CHGS method for numerical forecasting of typhoon waves, where a model for the growing wave spectrum was set up (see Eq. (2) in the text). The model involves a parameter indicating the growing degree of wind wave, i. e. ,the mean wave age β. When βvalue is small, the wave energy is chiefly concentrated near the peak frequency, so that the spectral peak gets high and steep; with the increase of β the spectral shape gradually gets lower and gentler; when β=Ⅰ, the wave fully grows, the growing spectrum becomes a fully grown P-m spectrum. The model also shows a spectral “overshooting” phenomenon within the “balance zone”.

关键词： Spectrum of waves in growing phase CHGS method for numerical forecasting of typhoon waves

Heat oscillation in the upper ocean of the southern South China sea

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 1992年第3期11卷 375-387页

作者： He Youhai, Guan Cuihua and Gan Zijun South China sea.Institute of Oceanology, Academia Sinica, Guangzhou 510301, China

Data used in this study are temperature/depth profiles taken over the upper 400 m of the ocean in the southern South China sea.(4°-14° N, 106°-120° E) for the period 1961-1973. The data are analyzed on the grid 2 (latitude) by 2 (longitude) in space and bimonthly in time. The vertically averaged temperature (TAV) over the upper 100 m of the ocean is calculated as the estimate of the heat content in the upper *** TAV is cooler in the northwest region of the study area and warmer in the southeast in the annual and sea.onal mean figures. The first EOF (Empirical Orthogonal Function) of anomalous TAV accounts for 41 % of the total variance for the period 1961-1973. The time function associated with it displays a significant interannual changes in the heat content, with 2-4 a oscillation period and associated with the ENSO events. During ENSO event TAV increases with the tendency of increasing towards equator along the basin. This anomalous states also exist in the water layers below 100 m depth. The isotherm is usually deepened during ENSO period. The deepened amplitude of the isotherm decreases with depth, and varies with ENSO events, sea.ons and regions. The reason for that is related to weak monsoon in El Nino year and associated eddy activity. Besides this, there is a gain in heat in the upper ocean because of the strong subtropical high during ENSO period.

关键词： heat Heat oscillation in the upper ocean of the southern South China sea

Fouling in offshore areas southeast of the Zhujiang(Pearl)River Delta,the northern South China sea

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2003年第2期22卷 201-212页

作者： Yan Tao, Yan Wenxia, Dong Yu, Liang Guanhe, Yan Yan, Wang Huajie South China sea.Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China. South China sea.Inst. of Oceanology Chinese Academy of Sciences Guangzhou 510301 China

In order to understand the type and extent of marine fouling in offshore areas southeast ofthe Zhujiang (Pearl) River delta, within the period form may 1986 to June 1987, two biological buoys were deployed at water depths of 95 m and 113 m located in 114 km and 160 km off the coast of Hong Kong, respectively. moreover, the fouling community of a marex hydrological buoy located in 115 m depth water 172 km off Hong Kong was also surveyed. The results show that a total of 78 species were collected and identified. The panels exposed for 3 months were mainly dominated by stalked barnacles Conchoderma hunteri and Lepas anatifera and hydroids Orthopyxis sp. As for the buoys, including the subsurface buoy, and their mooring systems exposed for 6 and 12 months, respectively, some hard foulers such as common oysters, pearl oysters, acorn barnacles and bryozoans were also found. The compositions of fouling communities also varied greatly with depth.

关键词： Biofouling offshore structures the South China sea