检索结果-南通市图书馆

Wind tunnel test on the effect of metal net fences on sand flux in a Gobi Desert, China

Journal of Arid Land 2017年第6期9卷 888-899页

作者： WANG Tao qu jianjun LING Yuquan XIE Shengbo XIAO Jianhua Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and Resources Chinese Academy of. Sciences Lanzhou 730000 China Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China Ningxia. University Yinchuan 750021 China Dunhuang" Gobi and Desert" Ecology and Environment Research Station Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Dunhuang 736200 China University of Chinese Academy of Sciences Beijing 100049 China

The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand. However, the shielding effect of the sand-blocking fence is below the expectation. In this study, effects of metal net fences with porosities of 0.5 and 0.7 were tested in a wind tunnel to determine the effectiveness of the employed two kinds of fences in reducing wind velocity and restraining wind-blown sand. Specifically, the horizontal wind velocities and sediment flux densities above the gravel surface were measured under different free-stream wind velocities for the following conditions： no fence at all, single fence with a porosity of 0.5, single fence with a porosity of 0.7, double fences with a porosity of 0.5, and double fences with a porosity of 0.7. Experimental results showed that the horizontal wind velocity was more significantly decreased by the fence with a porosity of 0.5, especially for the double fences. The horizontal wind velocity decreased approximately 65% at a distance of 3.25 m（i.e., 13 H, where H denotes the fence height） downwind the double fences, and no reverse flow or vortex was observed on the leeward side. The sediment flux density decreased exponentially with height above the gravel surface downwind in all tested fences. The reduction percentage of total sediment flux density was higher for the fence with a porosity of 0.5 than for the fence with a porosity of 0.7, especially for the double fences. Furthermore, the decreasing percentage of total sediment flux density decreased with increasing free-stream wind velocity. The results suggest that compared with metal net fence with a porosity of 0.7, the metal net fence with a porosity of 0.5 is more effective for controlling wind-blown sand in the expansive windy area where the Lanzhou-Xinjiang High-speed Railway runs through.

关键词： wind-blown sand wind tunnel experiment porous fence flow field sediment flux density Lanzhou-Xinjiang High-speed Railway Gobi Desert

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Morphology and formation mechanism of sand shadow dunes on the Qinghai-Tibet Plateau

引用

Journal of Arid Land 2015年第1期7卷 10-26页

作者： JianHua XIAO jianjun qu ZhengYi YAO YingJun PANG KeCun ZHANG Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Dunhuang Gobi and Desert Ecology and Environment Research Station Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Gansu Center for Sand Hazard Reduction Engineering and Technology

The formation and development of dunes depend on wind-blown sand movement which is affected by the characteristics of sand material, topography, wind regimes and other factors. In this paper, we investigated two sand shadow dune groups in Shigatse and Za＇gya Zangbo of Tibet and an individual dune in Da Qaidam of Qinghai, and analyzed their topographies and morphologies, and the physical characteristics of the sand, wind regime and sand transport. Formed under harsh conditions behind hills, these mature sand shadow dunes are hundreds of meters long, have significant ridges and crescent dunes downwind, and have a hill pass on one or both sides. Wind tunnel experiments revealed that the hill gap and wind velocity are important factors in the formation of these dunes Sand shadow dunes formed only when the gap spacing is two-thirds of the hill height. When wind velocities are 20 m/s, the sand body is divided into two parts. The hill pass allows the transport of sand by wind, creating a ＂nar- row-pipe effect＂, which causes the transported material to gradually accumulate in the center of the shadow zone. We observed that the following are needed for sand shadow dunes to form：（1） strong winds, sufficient sand, suitable obstacles and a dry climate; （2） one or both sides of the obstacle forming the shadow zone must have a hill pass; and （3） the windward side of the obstacle must have a wide, flat area, providing adequate spacing for wind flow and transport of material and the leeward side must have a sufficiently broad, flat area to allow the release of the transported material. Research results on these newly discovered dunes on the Qinghai-Tibet Plateau could contribute to the understanding of dune geomorphology.

关键词： sand shadow dune morphology aeolian landform wind tunnel Qinghai-Tibet Plateau

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Computational fluid dynamics evaluation of the effect of different city designs on the wind environment of a downwind natural heritage site

引用

Journal of Arid Land 2014年第1期6卷 69-79页

作者： BenLi LIU jianjun qu QingHe NIU JunZhan WANG KeCun ZHANG Dunhuang Gobi & Desert Ecological and Environmental Research Station Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

Disturbance in wind regime and sand erosion deposition balance may lead to burial and eventual vanishing of a *** study conducted 3D computational fluid dynamics(CFD)simulations to evaluate the effect of a proposed city design on the wind environment of the Crescent Spring,a downwind natural heritage site located in Dunhuang,Northwestern *** terrain data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)Digital Elevation Model(DEM)were used to construct the solid surface ***-state Reynolds Averaged Navier-Stokes equations(RANS)with shear stress transport(SST)k-ωturbulence model were then applied to solve the flow field ***-use changes were modeled implicitly by dividing the underlying surface into different areas and by applying corresponding aerodynamic roughness *** were performed by using cases with different city areas and building *** show that the selected model could capture the surface roughness changes and could adjust wind profile over a large *** profiles varied over the greenfield to the north and over the Gobi land to the east of the ***,different wind speed reduction effects were observed from various city construction *** current city design would lead to about 2 m/s of wind speed reduction at the downwind city edge and about 1 m/s of wind speed reduction at the north of the spring at 35-m *** the city height in the north greenfield area could efficiently eliminate the negative effects of wind *** contrast,restricting the city area worked better in the eastern Gobi area compared with other parts of the study *** speed reduction in areas near the spring could be limited to 0.1 m/s by combining these two abatement *** CFD method could be applied to simulate the wind environment affected by other land-use changes over a large terrain.

关键词： computational fluid dynamics wind environment wind profile large terrain Crescent Spring

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Sand control effect of HDPE sandbreak nets with different porosity structure

引用

Research in Cold and Arid Regions 2022年第6期14卷 403-411页

作者： QingHe Niu jianjun qu AiGuo Zhao LiHai Tan Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China Research Station of Gobi Desert Ecology and Environment in Dunhuang of Gansu Province(Dunhuang) LanzhouGansu 730000China

Straw checkerboard sand barriers with a porous structure that consists of a pervious upper portion and a dense lower portion are widely used to achieve great sand control *** this,and resolving the serious earth surface undercutting problem after HDPE sandbreak net checkboard barriers setting,the authors used HDPE(high-density polyethylene)materials to prepare new sandbreak materials with a similar porous *** wind tunnel simulations and field sand control monitoring,we compared the sand control effect of three HDPE sandbreak nets with different porosity *** to the sandbreak net with uniform porosity structure,the three types of HDPE sandbreak nets with different porosity structure had poorer effect on reducing sand transport rates,but had longer effective protection distance before sandbreak nets at low wind velocity conditions(14 m/s)and longer effective protection distance between sandbreak nets at all experimental wind velocity *** and sand control effect characteristics of HDPE sandbreak nets with different porosity structure provide an ideal material on semiburied checkerboard sand barriers for sand *** contrast,uniform-type sandbreak nets are used as materials on high upright sand fences for sand *** HDPE sandbreak nets can be used to replace traditional sandbreak materials and have a very high potential for widespread and popular application in aeolian sand disaster control.

关键词： HDPE sandbreak nets Different porosity structure Checkerboard sand barriers High upright sand fence Sand control effect

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dynamic changes of a typical linear dune in the Tengger Desert

引用

Journal of Arid Land 2010年第4期2卷 272-278页

作者： Zhang, KeCun Kai, KenJi qu, jianjun Ling, Yuquan Niu, QingHe Chinese Acad Sci Dunhuang Gobi & Desert Ecol & Environm Res Stn Cold & Arid Reg Environm & Engn Res Inst Lanzhou 730000 Peoples R China Nagoya Univ Grad Sch Environm Studies Nagoya Aichi 4648601 Japan

The dynamical processes of a typical linear dune including morphological features, dune ridge swing range and crest height were investigated at different monitoring periods in the hinterland of Tengger Desert. The results indicated that the development of linear dune depends on not only the northwesterly prevailing wind, but also the winds from northeast and southwest. The dune ridge swayed along its fundamental strike and took on an eastward movement gradually. The original dune strike was NW70° on August 3, 1994, and then changed to NE15° on April 21, 2001. The dune crest increased by 1.8 m longitudinally, which manifested strong wind-blown sand activities in this region. Wind erosion frequently occured at the bottom of sand dune, while sand accumulation appeared on its mid-upper section. The mean wind erosion depth was 25 cm on the bottom of linear dune and the height difference of the control points on the dune’s ridge was 1.13 m. Although the linear dune swayed laterally, the horizontal displacement of its ridge moved eastward 5.8 m averagely. The swing range of the dune crest line is very distinct, with a maximum value of 13.2 m. The highest site on the K-profile swayed on both sides of the dune ridge and the heights were 19.88 m at the control point K5, 19.61 m at K6 and 19.05 m at K7, respectively. The results indicated that the lateral swing of the linear dune was distinct under the northwesterly wind and it moved toward east gradually.

关键词： linear sand dune dynamic change morphological feature Tengger Desert

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Desert vegetation distribution and species-environment relationships in an oasis-desert ecotone of northwestern China

引用

Journal of Arid Land 2019年第3期11卷 461-476页

作者： ZHAO Peng qu jianjun XU Xianying YU Qiushi JIANG Shengxiu ZHAO Heran Key Laboratory of Desert and Desertification Northwest Institute of Eco-environment and ResourcesChinese Academy of SciencesLanzhou 730000China State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating Gansu Desert Control Research InstituteLanzhou 730070China Gansu Minqin National Field Observation and Research Station on Ecosystem of Desertification Rangeland Minqin 733000China University of Chinese Academy of Sciences Beijing 100049China

Environmental heterogeneity significantly affects the structure of ecological *** vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mechanism(s)driving vegetation succession,especially in the ecologically fragile *** this study,based on the quantitative analysis of plant community and environmental factors in 68 plots at 10 different transects in the Minqin oasis-desert ecotone(ODE)of northwestern China,we investigated desert vegetation distribution and species-environment relationships using multivariate ***-way indicator species analysis(TWINSPAN),detrended correspondence analysis(DCA),and canonical correspondence analysis(CCA)methods were used.A total of 28 species,belonging to 27 genera in 8 families,were ***,Zygophyllaceae,Gramineae,and Leguminosae were the largest *** and perennial herbs accounted for 28.60%of the total number of plants,while shrubs(42.90%)were the most *** tangutorum was the constructive species of the desert plant *** divided the 68 plots surveyed in this study into 7 community types,according to the results of *** distribution of these 7 communities in the DCA ordination graph showed that species with a similar ecotype were clustered *** of CCA indicated that groundwater was the dominant factor influencing vegetation distribution,while distance between plot and oasis(Dis)and soil electrical conductivity(EC)were the local second-order *** study suggests that optimizing the utilization of groundwater in oases is key to controlling the degradation of desert *** favorable topographic conditions of sand dunes should be fully utilized for vegetal dune stabilization,and the influence of soil salinity on the selection of afforestation tree species should be considered.

关键词： TWINSPAN classification ordination desert plant groundwater oasis-desert ecotone species-environment relationship Minqin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

ROLLING CONTACT FATIGUE BEHAVIOR OF CERAMIC BALLS LUBRICATED BY LUBRICANTS WITH EXTREME PRESSURE ADDITIVES

引用

Chinese Journal of Mechanical Engineering 2006年第2期19卷 195-199页

作者： ZHANG Feng S0NG Baoyu qu jianjun LIU Weimin School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001 China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000 China

An experiment is conducted to investigate the effects of lubricant10#, which contains extreme pressure additives T304 and T305, on the rolling contact fatigue （RCF） life of the contact pairs of a Si3N4 ceramic ball and a steel rod. The experimental investigation is carried out using a ball-rod RCF test rig. The results show that the extreme pressure additives increase the anti-contact-fatigue performance of ceramic balls; When the content of the additives varies from 1% to 5%, the increasing gradient of the RCF life curve decreases; And the oil sample with 1% T305 additive corresponds to the maximal gradient of the RCF life curve, with the RCF life being increased by about 10.77 times. The fatigue surface of the ceramic ball is analyzed with scanning electron microscope （SEM） and X-ray electron dispersion analysis（EDAX）, and the physical model of extreme pressure additives＇ increasing the RCF life of the ceramic ball is proposed. It is found that the extreme pressure additives form a corrosive film and a transfer film on the surface of the ceramic ball, which decrease the surface tangential stress, and to increase the surface energy is the most effective means for increasing the RCF life.

关键词： Ceramic bearing Si3N4 ceramic Rolling contact fatigue Extreme pressure additive

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Estimation of wind erosion from construction of a railway in arid Northwest China

引用

International Soil and Water Conservation Research 2017年第2期5卷 102-108页

作者： Benli Liu Larry E.Wagner Duihu Ning jianjun qu Dunhuang Gobi Desert Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China USDA-ARS Agricultural Systems Research Unit Fort CollinsCO 80526USA International Research and Training Center on Erosion and Sedimentation Bejing 100048China

A state-of-the-art wind erosion simulation model,the Wind Erosion Prediction System and the United States Environmental Protection Agency's AP 42 emission factors formula,were combined together to evaluate wind-blown dust emissions from various construction units from a railway construction project in the dry Gobi land in Northwest *** influence of the climatic factors:temperature,precipitation,wind speed and direction,soil condition,protective measures,and construction disturbance were taken into *** by daily and sub-daily climate data and using specific detailed management fles,the process-based WEPS model was able to express the beginning,active,and ending phases of construction,as well as the degree of disturbance for the entire scope of a construction *** Lanzhou-Xinjiang High-speed Railway was selected as a representative study because of the diversities of different cli-mates,soil,and working schedule conditions that could be *** erosion from different working units included the building of roadbeds,bridges,plants,temporary houses,earth spoil and barrow pit areas,and vehicle transportation were *** total wind erosion emissions,7406 t,for the first construction area of section LXS-15 with a 14.877 km length was obtained for quantitative *** method used is applicable for evaluating wind erosion from other complex surface dis-turbance projects.

关键词： Wind erosion Railway construction WEPS USEPA

来源：

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

Feathered sand ridges in the Kumtagh Desert and their position in the classification system

引用

Science China Earth Sciences 2011年第8期54卷 1215-1225页

作者： qu jianjun LIAO KongTai DONG GuangRong NIU QingHe JING ZheFan HAN QinJie Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Forestry Technical Popularization Master Station of Gansu Province Lanzhou 730046 China

Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km 2 and consist of crescent sand ridges and interridge tongue-shaped *** in grain size,mineral composition and albedo between crescent sand ridges and tongue-shaped dunes,and between windward and leeward slopes of tongue-shaped dunes,result in their feathery appearance in aerial and satellite *** of the sand drift potential in the region show that the sand-moving wind for feathered sand ridges can be divided into three sectors;***-northeasterly,easterly and east-northeasterly sectors roughly corresponding to the southeast,northwest and southwest slip *** findings suggests that the crescent sand ridges resulting from the connection of barchan dunes along the prevailing wind direction are longitudinal dune ridges rather than transverse ***-shaped dunes and quasi-dune shapes have obvious distinctions and are new transverse dune *** to McKee's dune shape classification,the feathered sand ridges are not a deformation dune type but a complex *** to Wu's dune morphological and genetic classification,they are not dune ridges or compound dune ridges that form under the action of unidirectional winds or two winds intersecting at an acute angle,but are complex dune ridges that form under the action of three winds intersecting at an acute angle.

关键词： Kumtagh Desert feathered sand ridge tongue-shaped dune morphologic characteristics aeolian sand landform classification

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

引用

Journal of Mountain Science 2024年第1期21卷 113-130页

作者： ZHANG Kai ZHANG Hailong TIAN Jianjin qu jianjun ZHANG Xingxin WANG Zhenghui XIAO jianhua College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.

关键词： Folded linear HDPE sheet sand fence Numerical simulation Flow field characteristics Protection benefits

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：