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填料近表层分布对红外隐身涂层发射率的影响 被引量:2
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作者 周玉雪 任培旗 +1 位作者 张文杰 刘林华 《节能技术》 CAS 2023年第2期99-104,129,共7页
为研究红外隐身涂层中填料颗粒近表层非均匀分布对其发射率的影响,采用时域有限差分方法计算了单个圆片状填料颗粒在近表层分布时的吸收和散射特性参数,并代入由颗粒掺杂层和粘结剂层组成的双层辐射传输模型,采用Kubelka-Munk理论求解... 为研究红外隐身涂层中填料颗粒近表层非均匀分布对其发射率的影响,采用时域有限差分方法计算了单个圆片状填料颗粒在近表层分布时的吸收和散射特性参数,并代入由颗粒掺杂层和粘结剂层组成的双层辐射传输模型,采用Kubelka-Munk理论求解了涂层的表观光谱发射率,研究了填料颗粒近表层聚集程度、体积分数、几何尺寸对发射率的影响。结果表明:填料颗粒近表层聚集时涂层发射率低于均匀分布的情形,减小填料颗粒厚度和掺杂层厚度、提高填料掺杂体积分数和数密度可有效降低涂层的红外发射率。 展开更多
关键词 红外隐身涂层 发射率 表层分布 FDTD KUBELKA-MUNK理论
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北部湾防城港沿岸土壤^(137)Cs背景值及表层分布特征 被引量:5
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作者 徐伟 潘少明 +5 位作者 贾培宏 杨旭 曹立国 张威 阮向东 管永精 《地理研究》 CSSCI CSCD 北大核心 2015年第4期655-665,共11页
在北部湾防城港沿岸采集土壤样品,通过测量样品137Cs比活度及有机质含量,确定了137Cs背景值,分析表层土壤中137Cs分布特征,并探讨样品中137Cs活度与有机质含量的关系。结果表明:研究区土壤中137Cs背景值为626±15 Bq/m2,自然因素和... 在北部湾防城港沿岸采集土壤样品,通过测量样品137Cs比活度及有机质含量,确定了137Cs背景值,分析表层土壤中137Cs分布特征,并探讨样品中137Cs活度与有机质含量的关系。结果表明:研究区土壤中137Cs背景值为626±15 Bq/m2,自然因素和人为活动对137Cs在海岸带表层土壤中的再分配起到重要作用,不同表层样中137Cs比活度高低表现为:自然林地>水稻田>旱田>草地>河口海湾。把研究区土壤表层样及P01剖面样中137Cs含量与有机质含量进行相关性分析,结果表明:两者相关性显著,相关系数分别为0.414和0.732。通过探讨研究区137Cs背景值及沿岸表层土壤137Cs分布特征,可为进一步定量研究北部湾沿岸土壤侵蚀和堆积状况以及评价防城港红沙核电站运行后对环境的影响提供科学依据。 展开更多
关键词 137Cs背景值 表层土壤137Cs分布 有机质含量 大气沉降 北部湾 防城港
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同步辐射X射线反射技术及其在测量δ掺杂晶体中原子表层深度分布的应用
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作者 贾全杰 蒋最敏 《同步辐射装置用户科技论文集》 1998年第1期214-219,共6页
X射线低角反射实验技术是测定固体材料表层中杂质原子深度分布的有效手段。利用同步辐射X射线反射技术和近年来发展的由反射实验数据逆向求解原子深度分布的分层逼近法,研究了不同温度下分子束外延生长的δ掺杂(Sb)Si晶体样品,成功... X射线低角反射实验技术是测定固体材料表层中杂质原子深度分布的有效手段。利用同步辐射X射线反射技术和近年来发展的由反射实验数据逆向求解原子深度分布的分层逼近法,研究了不同温度下分子束外延生长的δ掺杂(Sb)Si晶体样品,成功地测量了样品中几个纳米范围内的Sb原子深度分布,所得结果表明,300℃以下是用分子束外延方法在Si晶体中生长Sb原子δ掺杂结构的合适温度。 展开更多
关键词 Δ掺杂 表层深度分布 锑原子 X射线反射 同步辐射 分层副近法 硅晶体 结构
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台湾海峡1999年8月表层温盐的走航式观测 被引量:4
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作者 陈华 胡建宇 +5 位作者 潘伟然 曾淦宁 陈照章 贺志刚 张彩云 李虹 《海洋通报》 CAS CSCD 北大核心 2001年第6期25-31,共7页
利用1999年8月台湾海峡的调查资料中走航式温盐仪的资料,对该海区的表层温盐分布进行分析?分析结果表明:调查期间在该海区存在多处上升流和冲淡水?台湾海峡调查海区的上升流区大致可分为两类:(1)海峡西部沿岸上升流区:平潭上升流区?东... 利用1999年8月台湾海峡的调查资料中走航式温盐仪的资料,对该海区的表层温盐分布进行分析?分析结果表明:调查期间在该海区存在多处上升流和冲淡水?台湾海峡调查海区的上升流区大致可分为两类:(1)海峡西部沿岸上升流区:平潭上升流区?东山上升流区和南澳上升流区;(2)台湾浅滩附近的上升流区?冲淡水主要有九龙江冲淡水?珠江冲淡水和闽江冲淡水,此外还有粤东沿岸水? 展开更多
关键词 台湾海峡 上升流 冲淡水 表层温盐分布 1998年
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Mo修饰的钼铁复合催化剂及其煤直接液化催化性能 被引量:2
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作者 谢晶 舒歌平 +4 位作者 杨葛灵 高山松 王洪学 卢晗锋 陈银飞 《化工学报》 EI CAS CSCD 北大核心 2021年第9期4675-4684,共10页
分别在Fe催化剂制备的沉淀、氧化和干燥阶段引入Mo合成了五种Mo修饰的钼铁复合催化剂,调控了Mo和Fe的结合形式。利用XRD、SEM、TEM、BET、XRF、XPS和H_(2)-TPR对催化剂进行表征,在500 ml高压釜内进行神华上湾煤的直接液化实验。结果表明... 分别在Fe催化剂制备的沉淀、氧化和干燥阶段引入Mo合成了五种Mo修饰的钼铁复合催化剂,调控了Mo和Fe的结合形式。利用XRD、SEM、TEM、BET、XRF、XPS和H_(2)-TPR对催化剂进行表征,在500 ml高压釜内进行神华上湾煤的直接液化实验。结果表明,钼铁协同催化作用促进了氢的活化和煤的分解,Mo修饰的复合催化剂的煤直接液化活性明显提高。Mo在催化剂表层分布有利于活性氢在工业循环溶剂和沥青类物质中的传递,促进沥青转化为油。Mo与Fe共沉淀会影响铁氧化物晶体形成和生长,使晶粒尺寸下降,比表面积和可还原度升高。Mo从氨水中引入形成均匀分散的小晶粒Mo-Fe复合化合物,液化油产率提高4.4%。浸渍引入Mo不改变铁氧化物结构,但Mo富集于催化剂表面提高了与反应物的碰撞概率,液化油产率提高5.0%。 展开更多
关键词 煤直接液化 钼铁复合催化剂 协同催化 表层分布 活性氢 油产率
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海洋碳循环模式(Ⅱ)──对印度洋的模拟结果分析 被引量:12
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作者 浦一芬 王明星 《气候与环境研究》 CSCD 2001年第1期67-76,共10页
把建好的海洋碳模式应用于印度洋区域,模拟得到了印度洋中与碳有关各化学量的表层分布、垂直分布和沿子午线面的等值线分布。与实测的GEOSECS(GeochemicalOcean—Sectinn Study)数据作对比,模... 把建好的海洋碳模式应用于印度洋区域,模拟得到了印度洋中与碳有关各化学量的表层分布、垂直分布和沿子午线面的等值线分布。与实测的GEOSECS(GeochemicalOcean—Sectinn Study)数据作对比,模式较好地再现了印度洋上营养盐浓度、总碳浓度、总碱度和溶解氧的二维分布。通过模拟还发现,在稳定状态下,大气和海洋中总碳含量的分布依赖于发生在海洋中的各种物理化学过程及边界条件,水平扩散系数Kh和光合作用常数率Kg对各化学量的分布有较大影响(以前有学者认为不太重要,如 Baes[1]);南印度洋中纬地区 10°S至 30°S是14C的重要向下渗透区域,人为排放的CO2可通过这片渗透区从海洋的表层输入海洋的深层。 展开更多
关键词 海洋碳循环模式 化学量 印度洋 表层分布 垂直分布 海洋气候 二氧化碳
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Effect of reagent films on coupling relationship between glass surface and particles 被引量:1
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作者 李明 吴超 +1 位作者 刘一静 闫晖 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第11期2799-2805,共7页
The experiments were conducted to investigate the behavior of airborne particles adhering to the glass slides which were coated by several reagent films. The results showed that the adhesion level could be significant... The experiments were conducted to investigate the behavior of airborne particles adhering to the glass slides which were coated by several reagent films. The results showed that the adhesion level could be significantly changed by the reagent films. There were no evident rules between the average size of particles and sampling time interval, the placing angle and reagent concentration. The average particle size on the surface coated by composite reagent (2-3 μm) was smaller than that on the single reagent coated surface, while the largest particle size (4-5 μm) was observed on the surface coated with the Tween 60. The experiment also demonstrated that the best adhesive performance was obtained on the surface which was coated with 0.5% SDBS and 0.5% fluorocarbon composite reagents. The experiment results indicated that each reagent had a certain optimum adhesive range to the particle. The composite reagents with different proportion of single reagents exhibited some particular physical and chemical properties, which could effectively change the adhesive performance between the solid surface and the particles. 展开更多
关键词 micro-particles ADHESION glass surface reagent film size distribution
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不同农田土壤类型对土壤中铜和锌含量的影响 被引量:1
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作者 宋晓蓝 李想 +3 位作者 郑童月 赵珊利 杜苗苗 丁晋利 《湖北农业科学》 2020年第16期26-29,共4页
选取4种典型农田土壤(潮土、砂姜黑土、黄褐土和褐土)并分析不同土壤类型铜(Cu)、锌(Zn)含量的分布特征。结果表明,不同土壤类型表层Cu含量高低表现为黄褐土>砂姜黑土>褐土>潮土;其中,黄褐土的Cu含量与潮土、砂姜黑土、褐土中... 选取4种典型农田土壤(潮土、砂姜黑土、黄褐土和褐土)并分析不同土壤类型铜(Cu)、锌(Zn)含量的分布特征。结果表明,不同土壤类型表层Cu含量高低表现为黄褐土>砂姜黑土>褐土>潮土;其中,黄褐土的Cu含量与潮土、砂姜黑土、褐土中的Cu含量有显著性差异;砂姜黑土表层中的Zn含量显著高于潮土、黄褐土和褐土,其最高值达225.40 mg/kg。从垂直分布特征来看,砂姜黑土和黄褐土表层(0~20 cm)中的Cu、Zn含量均显著高于20~40 cm、40~60 cm土层。潮土表层Cu含量与40~60 cm土层的Cu含量之间没有显著差异,而褐土表层Cu含量与20~40 cm、40~60 cm土层之间存在显著差异;黄褐土、砂姜黑土和褐土Zn含量随土壤深度的增加而呈现逐渐上升的趋势。4种不同类型土壤重金属Cu、Zn平均含量低于国家农用地土壤污染风险管控标准,处于清洁、尚清洁阶段。 展开更多
关键词 不同土壤类型 表层分布特征 垂直分布 Cu和Zn
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Multilayer distribution of carbon dioxide system in surface water of the Yellow Sea in spring 被引量:2
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作者 宫海东 张正斌 +2 位作者 张闯 刘莲生 邢磊 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2007年第1期1-15,共15页
Surface water can be divided into three layers from top downward: surface microlayer (SML, thickness≤50 μm), subsurface layer (SSL, ≈25 cm) and surface layer (SL, l-5m), among which the SML plays an importan... Surface water can be divided into three layers from top downward: surface microlayer (SML, thickness≤50 μm), subsurface layer (SSL, ≈25 cm) and surface layer (SL, l-5m), among which the SML plays an important role on sea-air interaction because of its unique physical-chemical property. Carbon dioxide system including DIC (dissolved inorganic carbon), Alk (alkalinity), pH and pCO: (partial pressure of CO2) in multilayered waters of the Yellow Sea was studied for the first time in March and May 2005. The results show that: DIC and Alk are obviously enriched in SML. The contents ofDIC, Alk and pCO2 become lower in turn from SML, SSL to SL, higher in March and lower in May, whereas for pH it was opposite. The relationship between DIC and Alk is clearly positive, but negative between pH and pCO2. Meanwhile, pCO2 and temperature/salinity is also in positive relation, pCO2 decreases with latitude increase. DIC and Alk show a similar variation trend with the maximum at 02:00-03:00, but pH and pCO2 show an opposite pattern. In addition, the distribution patterns are similar to each other in the three layers. The Yellow Sea is shown to be a sink of atmospheric CO2 in spring by two methods: (1) comparing pCO2 in seawater and atmosphere; (2) turning direction of "pH-depth" curve. Calculation on the base of pCO2 data in SML in four models shows that carbon flux in spring in the area was about -6.96×10^6 t C. 展开更多
关键词 the Yellow Sea carbon dioxide (CO2) system multiplayer surface microlayer carbon flux
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海流与潮流分析 被引量:1
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作者 俞光耀 张彦巨 《山东海洋学院学报》 1986年第1期83-106,130,共25页
本调查海域位于深浅急剧变化的大陆架边缘区域,海水流动相当复杂,既有半日和周日变化的潮流,又有变化周期较长的所谓节流,既有西北本乎洋强大的黑潮流经这里,又有受到长江等大河入海径流涵养的沿岸流在此汇合。在浅水的大陆架水域... 本调查海域位于深浅急剧变化的大陆架边缘区域,海水流动相当复杂,既有半日和周日变化的潮流,又有变化周期较长的所谓节流,既有西北本乎洋强大的黑潮流经这里,又有受到长江等大河入海径流涵养的沿岸流在此汇合。在浅水的大陆架水域,一般潮流较常流明显,有的区域潮流比常流大一个量级,而深水的东海海盆, 展开更多
关键词 海流 黑潮 表层流速分布 动力计算 断面结构
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Molecular Characterization of Sulfate-Reducing Bacteria Community in Surface Sediments from the Adjacent Area of Changjiang Estuary 被引量:3
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作者 ZHANG Yu ZHEN Yu +2 位作者 MI Tiezhu HE Hui YU Zhigang 《Journal of Ocean University of China》 SCIE CAS 2016年第1期107-116,共10页
Sulfate-reducing bacteria(SRB),which obtain energy from dissimilatory sulfate reduction,play a vital role in the carbon and sulfur cycles.The dissimilatory sulfite reductase(Dsr),catalyzing the last step in the sulfat... Sulfate-reducing bacteria(SRB),which obtain energy from dissimilatory sulfate reduction,play a vital role in the carbon and sulfur cycles.The dissimilatory sulfite reductase(Dsr),catalyzing the last step in the sulfate reduction pathway,has been found in all known SRB that have been tested so far.In this study,the diversity of SRB was investigated in the surface sediments from the adjacent area of Changjiang Estuary by PCR amplification,cloning and sequencing of the dissimilatory sulfite reductase beta subunit gene(dsr B).Based on dsr B clone libraries constructed in this study,diversified SRB were found,represented by 173 unique OTUs.Certain cloned sequences were associated with Desulfobacteraceae,Desulfobulbaceae,and a large fraction(60%) of novel sequences that have deeply branched groups in the dsr B tree,indicating that novel SRB inhabit the surface sediments.In addition,correlations of the SRB assemblages with environmental factors were analyzed by the linear model-based redundancy analysis(RDA).The result revealed that temperature,salinity and the content of TOC were most closely correlated with the SRB communities.More information on SRB community was obtained by applying the utility of Uni Frac to published dsr B gene sequences from this study and other 9 different kinds of marine environments.The results demonstrated that there were highly similar SRB genotypes in the marine and estuarine sediments,and that geographic positions and environmental factors influenced the SRB community distribution. 展开更多
关键词 sulfate-reducing bacteria (SRB) dissimilatory sulfite reductase beta subunit gene (dsrB) diversity
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Mineral distributions in surface sediments of the western South Yellow Sea:implications for sediment provenance and transportation 被引量:11
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作者 卢健 李安春 +1 位作者 黄朋 李艳 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第2期510-524,共15页
The South Yellow Sea(SYS) is strongly influenced by the substantial sediment loads of the Huanghe(Yellow)(including the modern Huanghe and abandoned old Huanghe subaqueous delta) and Changjiang(Yangtze) Rivers. Howeve... The South Yellow Sea(SYS) is strongly influenced by the substantial sediment loads of the Huanghe(Yellow)(including the modern Huanghe and abandoned old Huanghe subaqueous delta) and Changjiang(Yangtze) Rivers. However,the dispersal patterns of these sediments,especially in the western SYS,have not been clearly illustrated. In this study,we have analyzed clay minerals,detrital minerals,and grain sizes for 245 surface sediment samples(0–5 cm) collected from the western SYS. The clay minerals,on average,consist of 67% illite,14% smectite,11% chlorite,and 8% kaolinite. Clay minerals,detrital minerals,and grain size analyses of surface sediments,combined with water mass hydrology analysis,reveal that sediments in the western SYS are mainly derived from the modern Huanghe River,the abandoned subaqueous delta of the old Huanghe River,some material from the Changjiang,and coastal erosion. The clay minerals(especially illite and smectite) and quartz/feldspar ratio distribution patterns,reveal that the influence of modern Huanghe sediments can reach 35°N in the northwestern part of the study area,an influence that can be enhanced especially in winter owing to northerly winds. Conversely,sediments along the Jiangsu coast are mixed,in summer,with material from the Changjiang arriving via northward flow of Changjiang Diluted Water. The Subei Coastal Current carries the refreshed sediments northward into the western SYS. Sediment distribution and transport in the western SYS are mainly controlled by the oceanic circulation system that is primarily related to the monsoon. 展开更多
关键词 South Yellow Sea clay mineral Subei Coastal Current PROVENANCE
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The Ecological Distributions of N, P Utilizing Bacteria and Heterotrophic Bacteria in the Moderate Hypoxia Zone of the Changjiang Estuary
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作者 LIU Jingjing DU Ping +4 位作者 ZENG Jiangning CHEN Quanzhen SHOU Lu LIAO Yibo JIANG Zhibing 《Journal of Ocean University of China》 SCIE CAS 2013年第4期589-598,共10页
The distributions of N utilizing bacteria (denitrifying bacteria and ammonifying bacteria) ,P utilizing bacteria (organic phosphobacteria and inorganic phosphobacteria) and heterotrophic bacteria in the Changjiang Est... The distributions of N utilizing bacteria (denitrifying bacteria and ammonifying bacteria) ,P utilizing bacteria (organic phosphobacteria and inorganic phosphobacteria) and heterotrophic bacteria in the Changjiang Estuary,and the roles of main environmental factors in distributing bacteria,are explored with observations from two cruises in June and August 2006.Comparisons between the two important periods of initial hypoxia phase (June) and developed hypoxia phase (August) show differences in both bacterial distributions and the associated main environmental factors.First,the primary group of ammonifying bacteria has larger magnitude with spatial maximum value in the hypoxic stations related to sediment in August.The phosphobacterial abundance and detection rates in August are much lower than those in June,but the denitrifying bacterial abundance becomes greater in August.However,the difference of heterotrophic bacterial abundance between June and August is not obvious.Second,main environmental factors influencing bacteria vary from initial hypoxia phase to developed hypoxia phase.Two parameters (salinity and NO3) in surface water and five environmental parameters (pH,salinity,PO43,NO3and temperature) in bottom water and surface sediment play major roles in the bacterial abundance in June,while different parameter combinations (salinity and PO43) in surface water and different parameter combinations (DO,DOC,NO3,PO43 and pH) in bottom water and surface sediment play major roles in August.Moreover,the bottom bacteria distributions in area south of 31 N are related to the position of the Taiwan Warm Current in June.The bacterial abundance and distribution may respond to the environmental change in the hypoxia processes of initial phase and developed phase.During the hypoxia processes,the whole structure of bacterial functional groups probably turns to different states,causing the recycling of nutrient regeneration and aggravating hypoxia regionally. 展开更多
关键词 Changjiang Estuary HYPOXIA bacterial functional group
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THE DISTRIBUTION OF Sb ATOMS IN δ—DOPED SILICON CRYSTAL
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作者 贾全杰 蒋最敏 《同步辐射装置用户科技论文集》 1998年第1期206-213,共8页
关键词 锑原子 硅晶体 Δ掺杂 表层深度分布 X射线低角反射 同步辐射
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Spatiotemporal distribution of 1P1 antigen expression in the plexiform layers of developing chick retina
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作者 WANGHOUHUA QIUBAOSONG 《Cell Research》 SCIE CAS CSCD 1993年第2期187-193,共7页
Changes in the distribution of 1P1-antigen in the developing chick retina have been examined by indirect immunofluorescence staining technique using the novel monoclonal antibody (MAb) 1P1. Expression of the 1P1 antig... Changes in the distribution of 1P1-antigen in the developing chick retina have been examined by indirect immunofluorescence staining technique using the novel monoclonal antibody (MAb) 1P1. Expression of the 1P1 antigen was found to be regulated in radial as well as in tangential dimension of the retina, being preferentially or exclusively located in the inner and outer plexiform layers of the neural retina depending on the stages of development. With the onset of the formation of the inner plexiform layer 1P1 antigen becomes expressed in the retina. With progressing differentiation of the inner plexiform layer 1P1 immunofluorescence revealed 2 subbands at E9 and 6 sub-bands at E18. At postnatal stages (after P3) immunoreac-tivity was reduced in an inside-outside sequence leading to the complete absence of the 1P1 antigen in adulthood. 1P1 antigen expression in the outer plexiform layer was also subject to developmental regulation. The spatio-temporal pattern of 1P1 antigen expression was correlated with the time course of histological differentiation of chick retina, namely the synapse rich plexiform layers. Whether the 1P1 antigen was functionally involved in dendrite extension and synapse formation was discussed. 展开更多
关键词 chick retina development immunoflo-rescence plexiform layer
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Spatial Distribution of Heavy Metals in Surface Sediments of the Sakumo Lagoon, Ghana
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作者 V.K. Nartey K.A. Edor +1 位作者 L.K. Doamekpor L.H. Bobobee 《Journal of Environmental Science and Engineering》 2010年第11期17-27,共11页
The aim of this study was to determine the possible build up of heavy metals (Pb, Cu, Fe, Mn and Zn) in the Sakumo lagoon, a Ramsar site situated 3 km west of Tema, an industrial town in Ghana. To achieve this, surf... The aim of this study was to determine the possible build up of heavy metals (Pb, Cu, Fe, Mn and Zn) in the Sakumo lagoon, a Ramsar site situated 3 km west of Tema, an industrial town in Ghana. To achieve this, surface sediments were collected from three sections designated as south, centre and north of the lagoon. Sampling was done for a period of six months (September 2007 to February 2008) and concentrations of the heavy metals (Pb, Cu, Mn, Fe and Zn) in the sediments were determined using the atomic absorption spectrophotometer. The results were compared with the mean concentrations of these metals from a study carried out on the same lagoon in 2003. It was observed that concentrations of these heavy metals in the sediments showed a significant increase over the 2003 levels except for lead where a decrease was observed. The metals also showed spatially large variation from south to north. The spatial variations in concentrations indicate the different absorption capacities of the sediments in the lagoon, a phenomenon which shows that recent anthropogenic heavy metal pollution had occurred. Statistical analysis also showed significant correlation between Pb and Cu (0.968) at 0.01 confidence level and between Cu and Zn (0.869) at 0.05 confidence level. 展开更多
关键词 Heavy metal pollution benthic organisms industrial waste municipal sewage.
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Laboratory Application of Laser Grain-Size Analyzer in Determining Suspended Sediment Concentration
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作者 LIU Xiao FENG Xiuli +1 位作者 LIU Jie LIN Lin 《Journal of Ocean University of China》 SCIE CAS 2014年第3期375-380,共6页
Suspended sediment concentration(SSC) is an important parameter in marine sedimentology. With the development of technology, many acoustic and optical devices, such as the Laser In-Situ Scattering and Transmissometry,... Suspended sediment concentration(SSC) is an important parameter in marine sedimentology. With the development of technology, many acoustic and optical devices, such as the Laser In-Situ Scattering and Transmissometry, have been designed to measure in situ SSC and grain size distribution. But due to fund or other restrictions, many experiments were only conducted in laboratory, using an indoor laser grain-size analyzer and gravimetric method to measure grain size distribution and concentration, respectively. In this study the laboratory experiment is simplified by omitting the tiring step of gravimetric method. The connections between SSC and other parameters(obscuration, D50 and sorting index) were investigated based on 124 surface sediment samples collected from different offshore areas. A new method is developed for determining SSC in laboratory using a laser grain-size analyzer. 展开更多
关键词 suspended sediment concentration laser grain-size analyzer grain size parameters OBSCURATION
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Evaluation of Spatial and Vertical Variability of Nitrogen and Phosphorus in Sewage-Irrigated Soil in Tongliao, China
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作者 姚宏 薛晓博 +3 位作者 张士超 袁鑫 李桐 胡克林 《Transactions of Tianjin University》 EI CAS 2013年第4期241-247,共7页
The reuse of wastewater for the irrigation of farmlands is gaining popularity, and the nutrient leaching associated with wastewater irrigation is becoming a matter of concern. The variability of nitrogen and phosphoru... The reuse of wastewater for the irrigation of farmlands is gaining popularity, and the nutrient leaching associated with wastewater irrigation is becoming a matter of concern. The variability of nitrogen and phosphorus frac- tions in wastewater-irrigated soil was investigated in both horizontal and vertical directions in Kongjiaxiang, Tongliao, Inner Mongolia, China. The results showed that wastewater irrigation resulted in the concentrations of available N and P being 40.36% and 66.49% higher, respectively, than those with groundwater irrigation. Different forms of N and P exhibited significantly different distribution pattems. Higher concentrations of NO~ and total available N, as well as of those of Ca-P and total available P were observed near wastewater irrigation channels. Ca-P has a spatial distribu- tion pattern similar to that of available P. The concentrations of NO3 and NH4 were the highest in top soil and de- creased with depth. The complex interactions between nitrate leaching and nitrogen transformation processes (e.g., nitrification, denitrification, and mineralization) determined the vertical profile of NO3. The significant amount of NH~ loss inhibited its deep seepage. The Ca-bound compound contained more P than other inorganic fractions as a result of high Ca levels throughout the soil profile. The differences in the concentrations of Ca-bound P at different depths could be due to the upward flux or translocation of Ca from subsurface to surface soil and the sequestration of P. 展开更多
关键词 wastewater irrigation NITRATE PHOSPHORUS nutrient leaching
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Soil Quality in Relation to Agricultural Production in the North China Plain 被引量:5
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作者 XIA Min ZHAO Bingzi +1 位作者 Xiying HAO ZHANG Jiabao 《Pedosphere》 SCIE CAS CSCD 2015年第4期592-604,共13页
Sustainable agricultural production is of vital importance to food supply security. This study aimed to investigate crop yield response to spatial variability of soil quality at a county scale in the North China Plain... Sustainable agricultural production is of vital importance to food supply security. This study aimed to investigate crop yield response to spatial variability of soil quality at a county scale in the North China Plain (NCP) and subsequently derive key soil quality indicators. Soil samples were geo-referenced and taken in 2008 from both surface (0-20 cm) and subsurface (20-40 cm) layers in 132 fields throughout the Fengqiu County, located in the centre of the NCP, for subsequent soil properties' analyses. Annum crop yields were obtained from the same fields where soil samples were collected. Soil quality was evaluated based on a fuzzy set with 13 soil properties, and its spatial distributions were investigated by integrating geostatistical analysis and geographic information system (GIS) techniques. Soil quality indices were classified into five grades, and their spatial distributions were mapped within the county. The surface soil qualities were about one to two grades higher than the subsurface soil. The quality indices for surface and subsurface soils were positively associated with the annual crop yields, suggesting the importance of both. Soil organic matter, total nitrogen, available P, and available K contributed 50% of the combined weight to the soil quality index and were identified as key indicators of soil quality status in the area in terms of sustainability. 展开更多
关键词 crop yield geostatistical analysis key indicator spatial variability soil quality evaluation soil properties subsurfacesoil surface soil
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Numerical simulation of gurney flaps lift-enhancement on a low reynolds number airfoil 被引量:4
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作者 HE Xi WANG JinJun +3 位作者 YANG MuQing MA DongLi YAN Chao LIU PeiQing 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第10期1548-1559,共12页
Two-dimensional steady Reynolds-averaged Navier-Stokes (RANS) equations with transition shear stress transport (SST) model were solved to investigate the effects of Gumey flaps on the aerodynamic performance of a ... Two-dimensional steady Reynolds-averaged Navier-Stokes (RANS) equations with transition shear stress transport (SST) model were solved to investigate the effects of Gumey flaps on the aerodynamic performance of a low Reynolds number airfoil. This airfoil was designed for flight vehicles operating at 20 km altitude with freestream velocity of 25 rn/s. The chord length (C) of this airfoil is 5 m and the corresponding Reynolds number is 7.76× 10^5. Gurney flaps with the heights ranging from 0.25%C to 3%C were investigated. It has been shown that Gurney flaps can enhance not only the prestall lift but also lift-to-drag ratio in a certain range of angles of attack. Specially, at cruise angle of attack (3°), Gurney flap with the height of 0.5%C can increase lift-to-drag ratio and lift coefficient by 1.6% and 12.8%, respectively. Furthermore, the mechanisms of Gumey flaps to improve the aerodynamic performance were illustrated by analyzing the surface pressure distribution, streamlines and trailing-edge flow structure for this low Reynolds number airfoil. Specially, distinguished from some other numerical researches, the flow details such as the laminar separation bubble and transition phenomena for low Reynolds number airfoil with Gumey flaps were investigated and it was found that Gurney flaps can delay the transition onset position at small angles of attack (≤2°). However, with the increase of angles of attack, Gurney flaps will promote the boundary layer transition. 展开更多
关键词 gurney flaps lift-enhancement low reynolds number numerical simulation
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