检索结果-南通市图书馆

基于PMNT陶瓷的1-3型压电复合材料软模板法制备及其超声换能器研究

在线全文

学校读者我要写书评

暂无评论

功能材料 2024年第5期55卷 5001-5006页

作者：孙瑞雨李晓兵杨钊萍陈兴飞孙丰龙陈建伟夏子颐周长江上海理工大学健康科学与工程学院上海200093 中国科学院上海硅酸盐研究所上海200050 上海师范大学物理系光电材料与器件重点实验室上海200234 山东第一医科大学附属人民医院超声科济南250000

医用高频超声换能器广泛应用于人体及生物组织的精细结构成像。1-3型压电复合材料因具有较高的机电耦合系数和较低的声阻抗而成为高频超声换能器的核心材料。基于有限元计算和软模板法设计制备了高性能Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_... 详细信息

医用高频超声换能器广泛应用于人体及生物组织的精细结构成像。1-3型压电复合材料因具有较高的机电耦合系数和较低的声阻抗而成为高频超声换能器的核心材料。基于有限元计算和软模板法设计制备了高性能Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)陶瓷/环氧树脂压电复合材料,并对材料进行了系统的电学性能测试。结果显示该1-3型压电复合材料具有优异的声学综合性能,其厚度伸缩模式机电耦合系数k t达到70.1%,其声阻抗Z a达19.05 MRayl。利用该材料制备了高频超声换能器,其-6 dB带宽达85%,插入损耗为17.7 dB。结果表明使用软模板法制备的压电复合材料具有适合于超声成像的优异的综合性能,有望促进高频超声换能器的商业化应用。

关键词： 1-3型压电复合 PMNT陶瓷高频超声换能器软模板法

Development and Conservation of Glacier Tourist Resources——A Case Study of Bogda Glacier Park

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2006年第4期16卷 365-370页

作者： LIU Xuling yang zhaoping XIE Ting Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

Glacier is one kind of the most beautiful geological sightseeing in the world as well as a special kind of tourism *** characters of glacier tourism include scarcity,frangibility,localization of tourist activity,scien-tific connotation,and integrated function and *** paper summarizes the latest researches in developing glacier tourism *** the Bogda Glacier Park as an example,the authors analyze the characteristics of glacier tourism resources in detail and the conditions and potential threats of glacier tourism *** on glacier tourism development and protection are given as follows:1) to plan function subarea scientifically and rea-sonably;2) to combine tourism,scientific research with ecological education;3) to take countermeasures of environ-mental protection;4) to integrate tourism resources and strengthening regional ***,emphases are put forward on resources conformity along the tourism line and cooperation of tourism *** paper aims to seek after the coordination path in exploitation and protection of glacier tourism resources to guide the exploitation of other glacier tourism destinations.

关键词：博格达冰川冰川旅游资源资源开发资源保护旅游开发

Effects of freezing intensity on soil solution nitrogen and microbial biomass nitrogen in an alpine grassland ecosystem on the Tibetan Plateau,China

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2016年第5期8卷 749-759页

作者： yang zhaoping GAO Jixi yang Meng SUN Zhizhong Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology School of Environmental Science and EngineeringNanjing University of Information Science & Technology Nanjing Institute of Environmental Sciences Ministry of Environmental Protection State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem;however,the research on the impact of the freeze-thaw action on nitrogen processes of the alpine grassland ecosystem on the Tibetan Plateau has not yet attracted much *** this study,the impact of the freezing strength on the soil nitrogen components of alpine grassland on the Tibetan Plateau was studied through laboratory freeze-thaw simulation *** 0–10 cm topsoil was collected from the alpine marsh meadow and alpine meadow in the permafrost region of Beilu *** the experiment,the soil samples were cultivated at –10℃,–7℃,–5℃,–3℃ and –1℃,respectively for three days and then thawed at 2℃ for one *** results showed that after the freeze-thaw process,the soil microbial biomass nitrogen significantly decreased while the dissolved organic nitrogen and inorganic nitrogen significantly *** the freezing temperature was below –7℃,there was no significant difference between the content of nitrogen components,which implied a change of each nitrogen component might have a response threshold toward the freezing *** the freeze-thaw process can lead to the risk of nitrogen loss in the alpine grassland ecosystem,more attention should be paid to the response of the soil nitrogen cycle of alpine grasslands on the Tibetan Plateau to the freeze-thaw process.

关键词： freezing temperature microbial biomass nitrogen dissolved organic nitrogen inorganic nitrogen alpine grassland Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

柔性无损检测超声线阵换能器的仿真研究

建模与仿真 2024年第3期13卷 2223-2232页

作者：李尧夏子颐李晓兵孙瑞雨陈兴飞孙丰龙杨钊萍上海理工大学健康科学与工程学院上海上海师范大学物理系光电材料与器件重点实验室上海

为了突破传统刚性超声探头无法完全贴合零部件曲面的限制,论文设计了一种由压电材料PZT-5H和聚二甲基硅氧烷(PDMS)组成的柔性超声线阵换能器。针对设计的柔性换能器采用有限元分析方法对其电阻抗性能、脉冲回波特性进行了仿真分析,获得... 详细信息

为了突破传统刚性超声探头无法完全贴合零部件曲面的限制,论文设计了一种由压电材料PZT-5H和聚二甲基硅氧烷(PDMS)组成的柔性超声线阵换能器。针对设计的柔性换能器采用有限元分析方法对其电阻抗性能、脉冲回波特性进行了仿真分析,获得了换能器的中心频率,−6 dB带宽以及发射电压响应。此外分别仿真了此柔性换能器应用于凹面和凸面金属管时对其内部裂纹的检测情况。仿真结果显示换能器的中心频率为21.5 MHz,−6 dB带宽为51.2%。换能器为凹形和凸形时其声压级均满足检测需求,可以用于对钢管中裂隙进行检测。

关键词：线阵换能器柔性超声超声成像有限元仿真

Influence of tourist disturbance on soil properties, plant communities, and surface water quality in the Tianchi scenic area of Xinjiang, China

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 Arid Land 2016年第2期8卷 304-313页

作者： WEN Bin ZHANG Xiaolei yang zhaoping XIONG Heigang QIU yang Xinjiang Institute of Ecology and Geography Chinese Academy of SciencesUrumqi 830011China College of Resource and Environment Sciences Xinjiang UniversityUrumqi 830046China University of Chinese Academy of Sciences Beijing 100049China Department of Economic Management Huanghuai UniversityZhumadian 463000China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000China

The impact of tourist disturbance on the environment has become a focal issue of environmental science, ecology, and travel management studies. To assess the influence of tourist disturbance on soils and plants in the Tianchi scenic area of Xinjiang, China, we compared soil properties and plant community characteristics at 0, 5, 10, and 20 m from the tourist trail within areas at three different altitudes, where the intensities of tourist disturbance are distinct. Surface water quality was also studied at three different levels relative to the Tianchi Lake. The results showed that tourist disturbance significantly increased soil pH within 10 m from the trail and soil bulk density on the edge of the trail, but significantly reduced soil organic matter and total nitrogen contents within 5 m from the trail. The number of tree seedlings on the edge of the trail and the shrub coverage and height of herbaceous plants within 5 m from the trail significantly decreased due to tourist disturbance. Changes in herbaceous plant diversity differed by soil zones. In the high altitude region, tourist disturbance led to a remarkable increase in the herbaceous plant diversity on the edge of the trail, while in the low altitude region, tourist disturbance had a low impact on the diversity of herbaceous plants. In addition, tourist activities polluted the surface water, significantly reducing water quality. Thus, current tourist activities have a significant negative impact on the ecological environment in the Tianchi scenic area.

关键词： tourist disturbance soil properties plant communities water quality Tianchi scenic area

Evaluation on Tourism Ecological Security in Nature Heritage Sites——Case of Kanas Nature Reserve of Xinjiang,China

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2009年第3期19卷 265-273页

作者： LIU Xuling yang zhaoping DI Feng CHEN Xuegang Tourism School Xinjiang University of Finance ＆ Economics Urumqi 830012 China Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China School of Geography Science and Tourism Xinjiang Normal University Urumqi 830054 China

The nature heritages are the precious legacy of nature with outstanding scientific and aesthetic value. They are quite different from other common ecotourism areas, because of its original and unique system, sensitive and vulnerable landscape, and peripheral cultural features. Therefore, the tourism development in the nature heritage sites should be on the premise of ecological security. The evaluation index system of tourism ecological security in nature heritage sites was constructed in this article by AHP and Delphi methods, including nature ecological security, landscape visual security and local culture ecological security, and the security thresholds of indices were also established. In the indices' weights of the evaluation model, the nature ecological security ranked the highest, followed by tourist landscape visual security and culture ecological security, which reflected the influence degree of the limited factor to tourism ecological security. Then, this paper carried out an empirical study of Kanas of Xinjiang Uygur Autonomous Region, China, which has the potential to be the World Nature Heritage. On the basis of the data attained from survey and observation on the spot, as well as questionnaire answered by tourists and local communities, the ecological security status in Kanas was evaluated. The result showed that the status of Kanas tourism ecological security was better, but there had some limiting factors. Lastly, effective measures were put forward to ensure its ecological security.

关键词：喀纳斯自然保护区生态安全评价新疆维吾尔自治区世界自然遗产生态旅游区中国 Delphi方法生态安全指数

Suppressing the lattice oxygen diffusion via high-entropy oxide construction towards stabilized acidic water oxidation

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第3期17卷 1107-1113页

作者： Jing Ni zhaoping Shi Yibo Wang Jiahao yang Hongxiang Wu Pengbo Wang Kai Li Meiling Xiao Changpeng Liu Wei Xing State Key Laboratory of Electroanalytic Chemistry Jilin Province Key Laboratory of Low Carbon Chemistry PowerChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

The scale-up deployment of ruthenium(Ru)-based oxygen evolution reaction(OER)electrocatalysts in proton exchange membrane water electrolysis(PEMWE)is greatly restricted by the poor *** the lattice-oxygen-mediated mechanism(LOM)has been identified as the major contributor to the fast performance degradation,impeding lattice oxygen diffusion to inhibit lattice oxygen participation is imperative,yet remains challenging due to the lack of efficient ***,we strategically regulate the bonding nature of Ru–O towards suppressed LOM via Ru-based high-entropy oxide(HEO)*** lattice disorder in HEOs is believed to increase migration energy barrier of lattice *** a result,the screened Ti_(23)Nb_(9)Hf_(13)W_(12)Ru_(43)O_(x) exhibits 11.7 times slower lattice oxygen diffusion rate,84%reduction in LOM ratio,and 29 times lifespan extension compared with the state-of-the-art RuO_(2) *** work opens up a feasible avenue to constructing stabilized Ru-based OER catalysts towards scalable application.

关键词： ruthenium-based high-entropy oxide suppressing the lattice oxygen diffusion acidic oxygen evolution reaction

Stabilizing high-efficiency iridium single atoms via lattice confinement for acidic oxygen evolution

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

Nano Research 2024年第4期17卷 2492-2498页

作者： Yibo Wang Jiadong Jiang zhaoping Shi Hongxiang Wu Jiahao yang Pengbo Wang Shuai Hou Meiling Xiao Junjie Ge Changpeng Liu Wei Xing Laboratory of Advanced Power Sources Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026.China State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Jilin Province Key Laboratory of Low Carbon Chemical Power Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Key Laboratory of Physics and Technology for Advanced Batteries Ministry of EducationCollege of PhysicsJilin UniversityChangchun 130012China

Stable and efficient single atom catalysts(SACs)are highly desirable yet challenging in catalyzing acidic oxygen evolution reaction(OER).Herein,we report a novel iridium single atom catalyst structure,with atomic Ir doped in tetragonal PdO matrix(IrSAs-PdO)via a lattice-confined *** optimized IrSAs-PdO-0.10 exhibited remarkable OER activity with an overpotential of 277 mV at 10 mA·cm^(-2) and long-term stability of 1000 h in 0.5 M H_(2)SO_(4).Furthermore,the turnover frequency attains 1.6 s^(-1) at an overpotential of 300 mV with a 24-fold increase in the intrinsic *** high activity originates from isolated iridium sites with low valence states and decreased Ir–O bonding covalency,and the excellent stability is a result of the effective confinement of iridium sites by Ir–O–Pd ***,we demonstrated for the first time that SACs have great potential in realizing ultralow loading of iridium(as low as microgram per square center meter level)in a practical water electrolyzer.

关键词： lattice confinement iridium single atoms ultralow iridium loading acidic oxygen evolution proton exchange membrane water electrolysis

Study on Simulating Spatial Distribution and Varying Patterns of Urumqi’s Population

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

Chinese Journal of Population,Resources and Environment 2007年第3期5卷 31-36页

作者： Chen Xuegang yang zhaoping Zhang Xiaolei Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi Xingjing 830011 China Graduate School Chinese Academy of Sciences Beijing 100039 China

In this paper, an approach to simulate the spatial dis- tribution of urban population is proposed using urban land use and population statistical data through the geographical information systems (GIS). Then, the spatial population distribution of Urumqi as a case is simulated by the approach mentioned above and its varying patterns are analyzed by the raster population surface. As a result, producing raster population surface is more accurate and natural than the traditional choropleth map of population density. Concerning the spatial population distribution of Urumqi, the population density declines from south to north and the population distribution mainly presents "T-type", the population distribution presents multi-centre agglomeration and the population distribu- tion of the districts shows different features. The population den- sity varies significantly with the increase in the distance from central business district (CBD). Finally, it is found in this paper that the development history of districts, terrain and traffic road are main factors that have an influence Urumqi’s population dis- tribution. This paper tries to provide more accurate population data for the plan and management of urban land, traffic and public facilities in order to enrich the researches on urban population distribution.

关键词：模拟研究空间分布城市人口变化模式地理信息系统