检索结果-南通市图书馆

不同年龄不同性别儿童足底压力分布特征对比研究

在线全文

学校读者我要写书评

暂无评论

体育科学研究 2024年第4期28卷 49-54页

作者：徐文泉冯玲崔广泽胡宗祥北京航空航天大学体育部北京100191 北京市海淀区实验小学北京100037 首都体育学院体育教育训练学院北京100191 集美大学体育学院福建厦门361021

取XX小学100名7岁和10岁男女学生儿童为研究对象,通过Footscan平板系统对儿童进行站立和步行的足底压力数据采集,使用单因素方差分析对数据进行统计,深入了解儿童足底压力分布特征,对比其左右脚差异、年龄差异以及性别差异。结果表明:... 详细信息

取XX小学100名7岁和10岁男女学生儿童为研究对象,通过Footscan平板系统对儿童进行站立和步行的足底压力数据采集,使用单因素方差分析对数据进行统计,深入了解儿童足底压力分布特征,对比其左右脚差异、年龄差异以及性别差异。结果表明:静态站立时儿童重心落在足后区,一般在右后区,且10岁较7岁儿童静态中重心控制更好;儿童动态足底压力中,前足所受冲量最大,足跟次之,中足最小;前足中跖骨区所受冲量较大;从最大压强来看,足跟区受力最大,跖骨区受力大小大致表现为M3>M2>M5>M1>M4;且年龄增大,足跟区和第三跖骨区受力增大,女生比男生表现更为明显;儿童步态不均衡,中足区和足跟区的左右差异大,主要表现为左脚中足区各特征值大于右脚,而在足跟区各值小于右脚,且女生表现更为明显。结论:7岁较10岁儿童足跟过渡更快,步频快,同年龄段女生较男生更接近于成人动态足底压力情况。

关键词：儿童足底压力步态

Improved performance and prolonged lifetime of titania-based materials: sequential use as adsorbent and photocatalyst

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2015年第7期58卷 1211-1219页

作者： Yan Peng Minghui Li Shujuan Zhang guangze Nie Meng Qi Bingcai Pan State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University

Lifetime is a key index in the evaluation of environmentally functional materials. Although it is well known that adsorption is the first step in photocatalysis, very little work has been done on the sequential use of materials as both adsorbents and photo- catalysts. In this work, two titania-based materials, TiO2 xerogel and TiO2 photocatalyst nanoparticles, were fabricated and evaluated as adsorbent and photocatalyst for the remediation of contaminated water with an azo dye, Acid Orange 7 （AO7）, as the modeling pollutant. The TiO2 xerogel showed a high adsorption capacity to AO7 （769 mg/g） and could be regenerated eas- ily with diluted NaOH solution （0.01 mol/L） for several cycles. The exhausted xerogel was calcined at 400 ℃ for 3 h and used as a photocatalyst for the degradation of AO7. Compared to the nanoparticles directly prepared from fresh TiO2 xerogel, the TiO2 nanoparticles from adsorption exhausted xerogel showed a much higher photocatalytic activity upon both UV and visible light irradiation. Thus the titania-based materials were endowed with improved performance as well as prolonged lifetime.

关键词： titanium dioxide adsorbent reuse photocatalyst azo dye

深部极高地应力花岗岩隧道岩爆破坏特征及成因机理研究

在线全文

学校读者我要写书评

暂无评论

工程地质学报 2024年第3期32卷 1098-1111页

作者：周航张广泽赵晓彦陈明浩陈仕阔喻炳鑫中铁二院工程集团有限责任公司成都610031 四川省艰险山区轨道交通安全风险防控工程研究中心成都610031 西南交通大学地球科学与工程学院成都611756 西南交通大学土木工程学院成都610031

深部极高地应力花岗岩隧道施工过程中,岩爆灾害异常突出,硬岩岩爆不同程度地造成岩体片状剥落、棱板状破裂、岩块抛掷及强烈弹射等。为了揭示花岗岩隧道岩爆成因机制,综合地质调绘、监控量测、岩爆实录统计、室内岩石力学试验、微观分... 详细信息

深部极高地应力花岗岩隧道施工过程中,岩爆灾害异常突出,硬岩岩爆不同程度地造成岩体片状剥落、棱板状破裂、岩块抛掷及强烈弹射等。为了揭示花岗岩隧道岩爆成因机制,综合地质调绘、监控量测、岩爆实录统计、室内岩石力学试验、微观分析和数值模拟分析等方法对隧道高地应力及岩爆的形成、破坏特征及影响因素进行探讨分析。根据现场岩爆实录统计分析,花岗岩隧道岩爆破坏特征复杂多样,发生时间集中,高水平构造应力使靠近雅鲁藏布江河谷一侧岩爆烈度显著增大,大埋深高自重应力导致岩爆主要分布在隧道掌子面和拱顶。基于钻孔实测地应力数据和初始地应力场反演分析,发现花岗岩隧道地应力场由构造应力和自重应力共同主导,隧道沿线82.0%的区段处于高到极高地应力状态,为岩爆的发生提供内动力地质条件。室内岩石力学试验表明二长花岗岩和花岗闪长岩均具有中等岩爆倾向性,厚层状、强度大、刚度高、完整性好的岩体为岩爆提供充足的物源条件。受控于雅鲁藏布江缝合带地质构造作用以及新生代岩浆活动作用影响,花岗岩隧道呈现高地温特征,地温梯度为5.5℃/100 m,最高实测地温达到89.6℃,高温热力耦合作用加速岩爆发生并提高岩爆危险性等级。隧道施工工艺会改变围岩应力重分布,影响围岩的应力集中,造成一定的尺寸效应,影响岩爆发生的烈度等级、时间和空间分布。

关键词：花岗岩隧道极高地应力岩爆破坏特征成因机理高地温岩爆倾向性

Antimony(V) removal from water by hydrated ferric oxides supported by calcite sand and polymeric anion exchanger

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2014年第2期26卷 307-314页

作者： yangyang Miao Feichao Han Bingcai Pan Yingjie Niu guangze Nie Lu Lv State Key Laboratory of Pollution Control and Resources Reuse School of the Environment Xianlin Campus Nanjing University

We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides （HFOs） using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents （denoted as HFO-201 and IOCCS） were employed for Sb（V） removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb（V） removal by both composites, while increasing temperature from 293 to 313 K only improved Sb（V） uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb（V） than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3 would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for 1OCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb（V） adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb（V） adsorption by both hybrids was attributed to the inner sphere complexation of Sb（V） and HFO, and Ca（II） induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb（V） in the synthetic water could be effectively removed from 30 μg/L to below 5μg/L （the drinking water standard regulated by China）, and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201.

关键词： hydrated ferric oxides antimony nanocomposite adsorbents calcite anion exchanger

在线全文

学校读者我要写书评

暂无评论

基于流固耦合共轨高压油管振动特性研究

内燃机工程 2024年第5期45卷 28-36页

作者：范立云董伟杰李屿明卢港澳王广泽哈尔滨工程大学动力与能源工程学院哈尔滨150001

为了研究流固耦合作用下共轨系统高压油管的振动特性,建立了高压油管的有限元模型。首先根据输液管道动力学方程,利用ANSYS软件分析管道附加流体质量下的湿模态特性;然后以均方根(root-mean-square)量化时程内的振动能量,研究流固耦合... 详细信息

为了研究流固耦合作用下共轨系统高压油管的振动特性,建立了高压油管的有限元模型。首先根据输液管道动力学方程,利用ANSYS软件分析管道附加流体质量下的湿模态特性;然后以均方根(root-mean-square)量化时程内的振动能量,研究流固耦合作用下管道不同弯头的振动响应,不同燃油脉动率、压力及激励频率对管道流致振动的影响,最后对比了共振频率下管道增设管夹前后的振动特性。结果表明:流固耦合下管道固有频率下降,在高阶模态下降率较明显,附加质量系数超0.13;不同弯头振动差异较大;振动能量与燃油脉动率呈正相关,与压力大小并无直接关系;接近自振频率下管道发生共振,振幅会急剧增大至超标;并且增设管夹后共振现象消失,振动能量下降率超90%。

关键词：流固耦合高压油管湿模态振动特性均方根

在线全文

学校读者我要写书评

暂无评论

聚酯漆包线漆与其热解产物的共热解行为研究

中国塑料 2024年第8期38卷 53-61页

作者：朱光泽夏志东周炜王晓露吴玉锋郭福北京工业大学材料与制造学部北京100124 北京工业大学循环经济研究院北京100124 北京信息科技大学机电工程学院北京100192

将聚酯漆包线及其漆膜分别与漆膜热解所得焦炭进行共热解,利用X射线衍射、形貌分析、热重分析、CoatsRedfern积分法、红外分析等方法研究其共热解行为。结果表明,聚酯漆包线漆膜热解所得焦炭的石墨化程度较高且其表面呈褶皱状的微纳结... 详细信息

将聚酯漆包线及其漆膜分别与漆膜热解所得焦炭进行共热解,利用X射线衍射、形貌分析、热重分析、CoatsRedfern积分法、红外分析等方法研究其共热解行为。结果表明,聚酯漆包线漆膜热解所得焦炭的石墨化程度较高且其表面呈褶皱状的微纳结构。虽然焦炭存在继续热解情况,但焦炭的加入不仅可以使聚酯漆膜的质量损失率提高,还可以将其活化能降低16.9%。此外,焦炭可致使聚酯漆膜热解过程中逸出更多的含有O—H、C=O等含氧官能团物质以及CO_(2)。研究证明,聚酯漆包线热解所得焦炭与聚酯漆包线共热解后可以进一步促进聚酯漆包线的热解,不仅有助于降低能耗还可以进一步促进废漆包线热解回收铜的发展。

关键词：聚酯漆包线焦炭热解动力学红外分析

Effects of six years of simulated N deposition on gross soil N transformation rates in an old-growth temperate forest

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2018年第3期29卷 644-653页

作者： Peng Tian Jinbo Zhang Christoph Müller Zucong Cai guangze Jin College of Forestry Northeast Forestry UniversityHarbin 150040HeilongjiangPeople’s Republic of China School of Geography Sciences Nanjing Normal UniversityNanjing 210023People’s Republic of China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023People’s Republic of China Department of Plant Ecology(IFZ) Justus-Liebig University GiessenHeinrich-Buff-Ring 2635392 GiessenGermany School of Biology and Environmental Science University College DublinDublinIreland

Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition with four levels of N addition rate(N0, N30, N60, and N120) for6 years in an old-growth temperate forest in Xiaoxing’an Mountains in Northeastern China. We measured gross N transformation rates in the laboratory usingN tracing technology to explore the effects of N deposition on soil gross N transformations taking advantage of N deposition soils. No significant differences in gross soil N transformation rates were observed after 6 years of N deposition with various levels of N addition rate. For all N deposition soils, the gross NH~+ immobilization rates were consistently lower than the gross N mineralization rates,leading to net N mineralization. Nitrate(NO~-) was primarily produced via oxidation of NH~+(i.e., autotrophic nitrification), whereas oxidation of organic N(i.e., heterotrophic nitrification) was negligible. Differences between the quantity of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were not significant for any treatment, which likely explains the lack of a significant effect on gross nitrification rates. Gross nitrification rates were much higher than the total NO~- consumption rates,resulting in a build-up of NO~-, which highlights the high risk of N losses via NO~- leaching or gaseous N emissions from soils. This response is opposite that of typical N-limited temperate forests suffering from N deposition,suggesting that the investigated old-growth temperate forest ecosystem is likely to approach N saturation.

关键词： N deposition Gross soil N transformation Temperate forest ecosystem ^(15)N tracing technology

基于CNN-LSTM组合模型在地下水位预测中的应用

在线全文

学校读者我要写书评

暂无评论

水利规划与设计 2024年第9期 58-62,76页

作者：童光泽李计生牛最荣王鲁军甘肃农业大学水利水电工程学院甘肃兰州730070 甘肃省武威水文站甘肃武威733000

地下水的水位变化研究不仅对地下水资源管理具有重要意义,也对水资源利用和环境保护具有重要指导作用。文章以石羊河流域民勤盆地地下水位为研究对象,分别利用卷积神经网络(CNN)、长短时记忆网络(LSTM)及CNN-LSTM组合模型进行预测研究... 详细信息

地下水的水位变化研究不仅对地下水资源管理具有重要意义,也对水资源利用和环境保护具有重要指导作用。文章以石羊河流域民勤盆地地下水位为研究对象,分别利用卷积神经网络(CNN)、长短时记忆网络(LSTM)及CNN-LSTM组合模型进行预测研究。结果显示,CNN-LSTM组合模型在地下水位预测中表现出较高的准确性和可靠性;据预测,若按照现在的发展趋势,民勤盆地未来5年(2024—2028年)地下水位将以每年0.08m的速度缓慢下降。

关键词：卷积神经网络长短时记忆网络地下水位民勤盆地

Leaf nitrogen resorption is more important than litter nitrogen mineralization in mediating the diversity–productivity relationship along a nitrogen-limited temperate forest succession chronosequence

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2023年第1期10卷 132-140页

作者： Peng Zhang Xiao-Tao Lü guangze Jin Zhili Liu Mai-He Li Center for Ecological Research Northeast Forestry UniversityHarbin150040China Forest Dynamics Swiss Federal Institute for ForestSnow and Landscape Research WSLCH-8903BirmensdorfSwitzerland Erguna Forest-Steppe Ecotone Research Station CAS Key Laboratory of Forest Ecology and ManagementInstitute of Applied EcologyChinese Academy of SciencesShenyang110016China Key Laboratory of Sustainable Forest Ecosystem Management Ministry of EducationNortheast Forestry UniversityHarbin150040China Northeast Asia Biodiversity Research Center Northeast Forestry UniversityHarbin150040China Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains Ministry of EducationSchool of Geographical SciencesNortheast Normal UniversityChangchun130024China School of Life Science Hebei UniversityBaoding071000China

The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relationship between plant biodiversity and primary productivity is widely accepted for natural ecosystems, the roles of nutrient resorption and mineralization in mediating that relationship remains largely unknown. Here, we quantified the relative importance of nitrogen(N) resorption and N mineralization in driving plant community N investment and the correlation between species diversity and community productivity along an N-limited successional chronosequence of the mixed broadleaved–Korean pine(Pinus koraiensis) forest in northeastern China. Leaf N resorption efficiency(NRE) at the community level increased significantly along the successional chronosequence,whereas litter N mineralization rate decreased significantly. Leaf NRE was more important than litter N mineralization rate in driving the diversity–productivity relationship. However, higher leaf NRE led to less N mineralization as succession progressed along the chronosequence. Our results highlight the importance of the N resorption pathway rather than the N mineralization pathway for forest N acquisition with community succession,and they provide mechanistic insights into the positive effects of biodiversity on ecosystem functioning. In future forest management practices, we recommend appropriate application of N fertilizer to mitigate the adverse effects of N-poor soil on seedling regeneration during late succession and thus maintain the sustainable development of temperate forest ecosystems.

关键词： Community composition Diversity Ecosystem functioning N cycling N limited Niche complementarity Trade-off