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Study on the flow structure around discontinued vertically layered vegetation in an open channel

Journal of Hydrodynamics 2020年第3期32卷 454-467页

作者： naveed anjum Norio Tanakia Graduate School of Science and Engineering Saitama UniversitySaitama-shiJapan International Institute for Resilient Society Saitama UniversitySaitama-shiJapan

The flow structure and geomorphology of rivers are significantly affected by vegetation patterns. In the present study, the effect of vegetation in the form of discontinuous and vertically double layered patches particularly on the resulting flow turbulence was examined computationally in an open channel. A k-ɛ model was implemented in this research work which was developed using 3-D numerical code FLUENT (ANSYS). After the validation process of numerical model, the impact of discontinuous layered vegetation patches on the flow turbulence was investigated against varying vegetation density and patch length. The mean stream-wise velocities at specified positions showed larger spatial fluctuations directly upstream and downstream of vegetation elements, whereas sharp inflections in the profiles were witnessed at the top of smaller submerged elements i.e. z/hs= 1 (where z is the flow depth and hs is the smaller vegetation height). The reduction in flow velocity due to tall vegetation structure was more as compared with that of short vegetation. The mean velocity in the patch regions was visibly higher than that in the gap regions. The profiles of turbulent flow properties showed more rise and fall within the patches with a high vegetation density i.e. Ss/d= 4;and St/d= 8 (where Ss/d and St/d are the smaller and taller vegetation spacing, while d is the vegetation diameter) as compared with low vegetation density i.e. Ss/d= 8;and St/d= 16. The turbulent flow structure in the large patch and gap regions was found to be more stable than that in the small patches and gaps;whereas, due to the variation in distribution form of the patch, turbulence is relatively unaffected, and the flow structure variation is low. Turbulence was observed to be large, followed by a saw-tooth distribution within the patches;whereas, low turbulence is observed in the non-vegetation regions. The turbulent intensity acquired maximum of 13% turbulence for dense vegetation arrangement as compared to that of sparse arrangement having maximum of 9

关键词： Discontinuous and layered vegetation patches open channel flow numerical simulation mean flow velocity turbulence modeling flow characteristics

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Numerical investigation of velocity distribution of turbulent flow through vertically double-layered vegetation

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Water Science and Engineering 2019年第4期12卷 319-329页

作者： naveed anjum Norio Tanaka Graduate School of Science and Engineering Saitama UniversitySaitama 338-8570Japan International Institute for Resilient Society Saitama UniversitySaitama 338-8570Japan

The velocity structures of flow through vertically double-layered vegetation(VDLV)as well as single-layered rigid vegetation(SLV)were investigated computationally with a three-dimensional(3D)Reynolds stress turbulence model,using the computational fluid dynamics(CFD)code FLUENT.The detailed velocity distribution was explored with a varying initial Froude number(Fr),with consideration of the steady subcritical flow conditions of an inland tsunami.In VDLV flows,the numerical model successfully captured the inflection point in the profiles of mean streamwise velocities in the mixing-layer region around the top of short submerged vegetation.An upward and downward movement of flow occurred at the positions located just behind the tall and short vegetation,respectively.Overall,higher streamwise velocities were observed in the upper vegetation layer due to high porosity,with Pr=98%(sparse vegetation,where Pr is the porosity),as compared to those in the lower vegetation layer,which had comparatively low porosity,with Pr=91%(dense vegetation).A rising trend of velocities was found as the flow passed through the vegetation region,followed by a clear sawtooth distribution,as compared to the regions just upstream and downstream of vegetation where the flow was almost uniform.In VDLV flows,a rising trend in the flow resistance was observed with the increase in the initial Froude number,i.e.,Fr?0.67,0.70,and 0.73.However,the flow resistance in the case of SLV was relatively very low.The numerical results also show the flow structures within the vicinity of short and tall vegetation,which are difficult to attain through experimental measurements.

关键词： Vertically double-layered vegetation Single-layered rigid vegetation Numerical modeling FLUENT Velocity distribution Turbulent flow

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Influence of Water Ageing on Mechanical Properties of CaCO<sub>3</sub>Filler Filled Epoxy Resin and <em>Sansevieria</em>/Carbon Fiber Reinforced Composites

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Open Journal of Composite Materials 2019年第1期9卷 1-20页

作者： naveed anjum Bheemappa Suresha Somanahally Lingaiah Ajit Prasad Department of Mechanical Engineering Vidya Vikas Institute of Engineering & Technology Mysuru India Department of Mechanical Engineering The National Institute of Engineering Mysuru India Department of Mechanical Engineering PES College of Engineering Mandya India

The present paper studies water absorption behavior and its consequence on mechanical properties of untreated and chemically treated Sansevieria /carbon fiber reinforced hybrid epoxy (Sria/CF-Ep) composite with calcium carbonate (CaCO3) nanoparticles. Sansevieria /carbon fiber (30/5 wt%) reinforced hybrid epoxy composite with 1.5, 3 and 4.5 wt% of CaCO3 have been developed by hand lay-up method followed by heat press. The water absorption characteristics of the Sria fibers were obtained by immersing the composite samples in sea water at room temperature, until reaching their water content saturation level. The dry and water-immersed hybrid composite samples were subjected to hardness, interlaminar shear, tensile, flexural, and impact tests. The water absorption development of hybrid composites was found to follow Fickian diffusion behavior. Diffusion coefficients and maximum water uptake results were evaluated;the outcome showed that both increased with an increase in filler loading to study the consequence of water penetration in the fiber/matrix interface. The study shows that the mechanical and water-resistant properties of the Sria were improved through chemical treatment and hybridization. Nevertheless, as a result of water penetrating the fiber/matrix interface, longer water-immersion times reduced the tensile and flexural strength of the composites.

关键词： Epoxy Sria Nano CaCO3 Sea Water Mechanical Properties

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Evaluation of SWAT Model performance on glaciated and non-glaciated subbasins of Nam Co Lake, Southern Tibetan Plateau, China

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Journal of Mountain Science 2019年第5期16卷 1075-1097页

作者： Muhammad ADNAN KANG Shi-chang ZHANG Guo-shuai Muhammad naveed anjum Muhammad ZAMAN ZHANG Yu-qing State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences China University of Chinese Academy of Sciences CAS Centre for Excellence in Tibetan Plateau Earth Sciences Key Laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau Research Chinese Academy of Sciences Division of Hydrology Water-Land Resources in Cold and Arid Regions Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Department of Irrigation & Drainage University of AgricultureFaisalabad Research Center of Fluid Machinery Engineering & Technology Jiangsu University School of Urban and Environmental Sciences Huaiyin Normal University

This paper presents an assessment of the Soil and Water Assessment Tool(SWAT) on a glaciated(Qugaqie) and a non-glaciated(Niyaqu) subbasin of the Nam Co Lake. The Nam Co Lake is located in the southern Tibetan Plateau, two subbasins having catchment areas of 59 km^2 and 388 km^2, respectively. The scores of examined evaluation indices(i.e., R^2, NSE, and PBIAS) established that the performance of the SWAT model was better on the monthly scale compared to the daily scale. The respective monthly values of R^2, NSE, and PBIAS were 0.94, 0.97, and 0.50 for the calibration period while 0.92, 0.88, and -8.80 for the validation period. Glacier melt contribution in the study domain was simulated by using the SWAT model in conjunction with the Degree Day Melt(DDM) approach. The conjunction of DDM with the SWAT Model ensued improved results during both calibration(R^2=0.96, NSE=0.95, and PBIAS=-13.49) and validation (R^2=0.97, NSE=0.96, and PBIAS=-2.87) periods on the monthly time scale. Average contribution(in percentage) of water balance components to the total streamflow of Niyaqu and Qugaqie subbasins was evaluated. We found that the major portion(99.45%) of the streamflow in the Niyaqu subbasin was generated by snowmelt or rainfall surface runoff(SURF_Q), followed by groundwater(GW_Q, 0.47%), and lateral(LAT_Q, 0.06%) flows. Conversely, in the Qugaqie subbasin, major contributor to the streamflow(79.63%) was glacier melt(GLC_Q), followed by SURF_Q(20.14%), GW_Q(0.13%), and LAT_Q(0.089%). The contribution of GLC_Q was the highest(86.79%) in July and lowest(69.95%) in September. This study concludes that the performance of the SWAT model in glaciated catchment is weak without considering glacier component in modeling; however, it performs reasonably well in non-glaciated catchment. Furthermore, the temperature index approach with elevation bands is viable in those catchments where streamflows are driven by snowmelt. Therefore, it is recommended to use the SWAT Model in conjunction with DDM or energy base model to simula

关键词： SWAT Model Nam Co Lake Degree-day melt model Streamflow Hydrological Response Unit

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Applicability of an ultra-long-range terrestrial laser scanner to monitor the mass balance of Muz Taw Glacier,Sawir Mountains,China

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Research in Cold and Arid Regions 2018年第1期10卷 47-54页

作者： FeiTeng Wang ChunHai Xu ZhongQin Li Muhammad naveed anjum Lin Wang State Key Laboratory of Cryospheric Science/Tien Shan Glaciological Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China University of Chinese Academy of Sciences Beijing 100049China

Glacier mass balance is a key component of glacier monitoring programs. Information on the mass balance of Sawir Mountains is poor due to a dearth of in-situ measurements. This paper introduces the applicability of an ultra-long-range terrestrial laser scanner(TLS) to monitor the mass balance of Muz Taw Glacier, Sawir Mountains, China. The Riegl VZ?-6000 TLS is exceptionally well-suited for measuring snowy and icy terrain. Here, we use TLS to create repeated high spatiotemporal resolution DEMs, focusing on the annual mass balance(June 2, 2015 to July 25, 2016). According to TLS-derived high spatial resolution point clouds, the front variation(glacier retreat) of Muz Taw Glacier was 9.3 m. The mean geodetic elevation change was 4.55 m at the ablation area. By comparing with glaciological measurements, the glaciological elevation change of individual stakes and the TLS-derived geodetic elevation change of corresponding points matched closely, and the calculated balance was-3.864±0.378 m w.e.. This data indicates that TLS provides accurate results and is therefore suitable to monitor mass balance evolution of Muz Taw Glacier.

关键词： glacier front variation geodetic mass balance Riegl VZ?-6000 terrestrial laser scanner Muz Taw Glacier Sawir Mountains

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Estimation of infiltration models parameters and their comparison to simulate the onsite soil infiltration characteristics

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International Journal of Agricultural and Biological Engineering 2019年第3期12卷 84-91页

作者： Hafiz Umar Farid Zahid Mahmood-Khan Ijaz Ahmad Aamir Shakoor Muhammad naveed anjum Muhammad Mazhar Iqbal Muhammad Mubeen Muhammad Asghar Department of Agricultural Engineering Bahauddin Zakariya UniversityMultan-Pakistan Center of Excellence in Water Resources Engineering(CEWRE) University of Engineering and TechnologyLahore-Pakistan Division of Hydrology Water-Land Resources in Cold and Arid Regions Cold and Arid Region Environmental and Engineering InstituteChinese Academy of SciencesLanzhou 730000China Graduate School of Water Resources Sungkyunkwan UniversitySuwon-si 2066Korea Department of Environmental Sciences COMSATS Institute of Information TechnologyVehari-Pakistan

Detailed knowledge about soil characteristics and site-specific final steady infiltration rate could help to increase the irrigation water use efficiency and decrease water losses in agricultural system.The experiments were conducted on Agricultural Research Farm of Bahauddin Zakariya University,Multan,Pakistan during 2016.The cumulative infiltration depth was measured using double ring infiltrometer at selected six points of the study area.Most commonly used infiltration models such as Kostikov’s,Philip’s and Horton’s were fitted to the field infiltration data for determination of model parameters and to find the best fit model for the study area.Kostikov’s infiltration model’s parameters such as empirical constant‘c’and infiltration decay constants‘k’were obtained in the ranges of 0.140-0.290 and 0.307-0.433,respectively.Philip’s infiltration model’s parameters such as sorptivity‘S’and conductivity constant‘A’were found in the ranges of 0.167-0.288 cm/min1/2 and-0.001 to-0.009 cm/min,respectively.Similarly,the Horton’s model’s‘parameter‘k’was obtained in the range of-1.619 to-1.238.The value of infiltration capacity at onset of infiltration(fo)was obtained as 1.744 to 3.491 for all the six points.The analysis showed that the infiltration models using the estimated parameters have satisfactory prediction capability at all the selected points.Horton’s model provided the lowest mean values for RMSE(0.235)and highest mean values for ME(94%);and the lowest mean values for MPD(0.127).This indicated that infiltration can be well-described by the Horton’s model at the selected site.

关键词： infiltration characteristics infiltration models parameters estimation perdition capability

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基于网丝传感器的燃料组件间两相流测量系统

基于网丝传感器的燃料组件间两相流测量系统

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作者： Muhammad naveed anjum 华北电力大学(北京)

学位级别：硕士

两相流存在于大多数热工流体环境中,在核电站燃料组件间热力水力工程实验中的气液两相流测量有重要意义。网丝传感器在采集分辨率和采集速度上比电阻式,超声波式传感器更有优势。压水堆燃料组件热工水力实验中的气液两相流的测量有对于... 详细信息

两相流存在于大多数热工流体环境中,在核电站燃料组件间热力水力工程实验中的气液两相流测量有重要意义。网丝传感器在采集分辨率和采集速度上比电阻式,超声波式传感器更有优势。压水堆燃料组件热工水力实验中的气液两相流的测量有对于研究特定工况下棒间流动特性、包壳传热特性均有重要意义。传统的两相流测量手段应用于燃料组件棒间空泡份额和气泡速度分布测量时,存在测量空间分辨率不够,或测量成本过高的局限性。针对上述问题,论文开展了适合燃料组件两相流测量的网丝传感器的研制,包括激励电路和接收电路设计、数据采集程序和图像重构程序、燃料组件模拟实验段设计等。与传统的网丝传感器不同的是,该设计同时将燃料棒本体作为激励电极,进一步提高了测量的空间分辨率。为了测试和验证所设计的网丝传感器,设计并制造了模拟燃料组件实验台架。通过安装了棒束的矩形实验段中产生上升气泡,模拟燃料组件间的两相流环境。在本课题中,电路设计是最重要的部分。电路设计得到改进。设计的电路在功率、成本和复杂度方面进行了优化。该控制是使用微控制器执行的,没有使用任何移位寄存器或多路复用器。电路简单,响应时间快,噪声低。

关键词：气液两相流网丝传感器电路设计燃料组件

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Investigation of Climate and Land Use Policy Change Impacts on Food Security in Eastern Sudan, Gadarif State

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Journal of Geographic Information System 2017年第5期9卷 546-557页

作者： Yousif Elnour Yagoub Zhongqin Li Omer Said Musa Muhammad naveed anjum Feiteng Wang Zhang Bo State Key Laboratory of Cryospheric Sciences/Tian Shan Glaciological Station Northwest Institute of Eco-Environment and Resources CAS Lanzhou China Department of Forest Protection and Conservation University of Khartoum-Faculty of Forestry Shambat Sudan College of Geography and Environmental Science Northwest Normal University Lanzhou China Division of Hydrology Water-Land Resources Northwest Institute of Eco-Environment and Resources CAS Lanzhou China

The aims of this research were to investigate the impacts of climate variations on land use policies, food security and vegetation cover in Gadarif State (eastern Sudan) during 1961 to 2013. Analysis of precipitation and temperature time series revealed that the annual precipitation was decreasing while the temperature was increased in the study area. Precipitation was decreasing at a rate of −50.3 mm/10a, while the temperature was increasing at a rate of 0.02°C/10a. The result of both SPEI and SPI showed that the Gadarif State has been changed to a high frequency of drought during 1961-2013. Sorghum yield showed a significant positive relationship with precipitation during July and October (CC = 0.364 and 0.321, respectively), moreover, a significant positive relationship between Sesame yield and precipitation was observed during July (CC = 0.335). A significant negative relationship between Sorghum yield and mean temperature was observed during the rainy season (July to October) with CC = −0.278. The yield productivity of Sorghum and Sesame had decreased significantly (from more than 800 kg/ha in the 1960s to less than 200 kg/ha in 2000s for Sorghum, while 500 kg/ha in 1960s to 100 kg/ha in 2000s for Sesame). The Mechanized Rain-fed Agriculture (MRA) area of Sorghum and Sesame in the Gadarif State had been increased from 1,058,241 ha to 2,799,655 ha during 1961 to 2013. Thus, we ultimately suggest that in the Gadarif State, policy makers must strive for an increase in yield per unit area by using sufficient fertilizers along with the gradual increment in tendencies of grain production through expansion of the cultivated area.

关键词： Climate Change Land Use Policy Change Food Security Gadarif State

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Glacier Mass-Balance Variation in China during the Past Half Century

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Journal of Geoscience and Environment Protection 2018年第5期6卷 37-58页

作者： Yousif Elnour Yagoub Zhongqin Li Ahmed A. H. Siddig Omer Said Musa Muhammad naveed anjum State Key Laboratory of Cryospheric Sciences/Tian Shan Glaciological Station Northwest Institute of Eco-Environment and Resources CAS Lanzhou China Faculty of Forestry Department of Forest Protection and Conservation University of Khartoum Shambat Sudan Division of Hydrology Water-Land Resources Northwest Institute of Eco-Environment and Resources CAS Lanzhou China

The aim of this study is to investigate the impact of temperature trend on glacier-mass balance, snow density, snowmelt, snow depth and runoff by using observations of nine glacier stations that covered most of the China over the period of 1979-2013. Trend analysis showed an increasing trend of temperature on all of the selected stations. On an average, temperature was increasing at the rate of 0.46/10a. The increasing trend of temperature showed a negative relationship with annual glacier-mass balance on most of the stations and caused a decrease in annual balance. Results of Pearson’s correlation analysis showed a highly significant negative correlation between temperature and snow density (correlation coefficient (CC = -0.661 at 0.01 significance level). There was a significant positive correlation between temperature and snowmelt (CC = 0.532 at 0.01 significance level). There was a significant negative correlation between temperature and snow depth (correlation coefficient (CC = -0.342 at 0.05 significance level). Moreover, there was a significant positive correlation between temperature and runoff (CC = 0.586 at 0.01 significance level). Increasing trend of temperature caused an increasing trend of annual snowmelt and runoff anomaly% at the rate of 24.82/10a and 9.87/10a, respectively. On the other hand, a declining trend in annual snow density and snow depth anomaly% was found at a rate of -5.32/10a and -1.93/10a, respectively. We concluded that the snow density, snowmelt and runoff are significantly sensitive to temperature in China. This contribution has provided information for further understanding of glacier variation and its influencing factors.

关键词： Glacier Mass-Balance Snow Density Snowmelt Snow Depth Runoff Climate Variation

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Investigation of Vegetation Cover Change in Sudan by Using Modis Data

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Journal of Geographic Information System 2017年第3期9卷 279-292页

作者： Yousif Elnour Yagoub Zhongqin Li Omer Said Musa Muhammad naveed anjum Feiteng Wang Chunhai Xu Zhang Bo State Key Laboratory of Cryospheric Sciences/Tian Shan Glaciological Station Northwest Institute of Eco-Environment and Resources CAS Lanzhou China Department of Forest Protection and Conservation Faculty of Forestry University of Khartoum Shambat Sudan College of Geography and Environmental Science Northwest Normal University Lanzhou China Division of Hydrology Water-Land Resources Northwest Institute of Eco-Environment and Resources CAS Lanzhou China

The aim of this research paper is to investigate the land cover changes in Sudan during the period 2001-2013 by using the MODIS data and to identify climatic factors influencing the land cover. SPSS v 17 software was used to investigate the correlation of climatic factors with vegetation cover;also ArcGIS v 10.2 software was used to analyze the NDVI data. The results indicate that the monthly average time scale, NDVI value curve distribution during the year, July to October as the center to both sides of decreasing vegetation cover in other months. In the spatial distribution of mean NDVI in Sudan, a high value was found in the southern part. On the other hand, a low value of vegetation cover was found in northern part. NDVI spaces mean presenting features values: autumn followed by summer then winter. By calculation of average annual and seasonal-NDVI values, it was deduced that the main vegetation cover type was increasing in winter and summer seasons at the rates of 0.014/10a and 0.008/10a, respectively. While winter-NDVI was decreasing the rate of 0.001/10a and 0.026/10a in autumn and on the annual scale, respectively. Annual NDVI showed a significant degradation (area = 12705.7 km2, 0.5% of total area) in the middle and eastern parts and significant improvement (area = 22485.4 km2, 0.9 % of the total area) in the southern part of the country due to the increase in precipitation and decrease in temperature. Mean summer and autumn-NDVI showed a significant difference 0.01% significance level with mean summer and autumn precipitation (correlation coefficients = 0.955 and 0.953, respectively). While there was a significantly negative relationship between mean summer and autumn-NDVI with mean summer and autumn temperature at 0.01% significance level (correlation coefficients = −0.270 and −0.820, respectively).

关键词： Land Cover Changes Climate Factors NDVI Sudan

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