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Newly-simplified method for hydrauli design of micro-irrigation laterals based on emission uniformity

排灌机械工程学报 2015年第8期33卷 691-700页

作者： Ju Xueliang Wu Pute Paul R.Weckler Zhu Delan Zhang Lin Institute of Soil and Water Conservation Northwest A&F University Institute of Water Saving Agriculture in Arid Areas of China Northwest A&F University Department of Biosystems and Agricultural Engineering Oklahoma State University College of Water Resources and Architectural Engineering Northwest A&F University

An analytical approach was developed to design a single uniformly sloping lateral in the micro-irrigation *** uniformity was used as the water application uniformity *** relations based on the energy-gradient-line approach were revamped to account for the spatial variance of emitter outflow and the emitter connections local energy *** pressure head grade line profiles were distinguished:uphill,horizontal,gentle downhill and steep *** expressions of emission uniformity by hydraulic variation for each pressure profile were developed based on the design variables:length and diameter of lateral,emitter spacing,emitter flow equation parameters,equivalent length characterizing local losses and ground *** design conditions for selecting emitter type,the number of emitters per plant and designing the diameter of the uphill and steep downhill laterals were also *** nonlinear equations for determining lateral diameter and lateral length were solved iteratively by using the built-in root-finding function of(Tools>Goal Seek…)in the calculation spreadsheet of Microsoft *** procedures also provide the options to fix the design lateral diameter with the commercial standard size or fix the design lateral length based on the field *** operating inlet pressure and maximum amplitude of the pressure head throughout the lateral could also be determined easily by the *** numerical applications with various slope combinations indicate that the proposed analytical approach produces results close to the accurate stepwise numerical *** comparison with Keller method,the proposed approach could produce more appropriate designs.

关键词： micro-irrigation lateral slopes hydraulic design e

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Phytoecological evaluation with detail floristic appraisal of the vegetation arround Malam Jabba,Swat,Pakistan

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Asian Pacific Journal of Tropical Biomedicine 2011年第6期1卷 461-467页

作者： Abdur Rashid Mohammad Farooq Swati Hassan Sher Mohammad N Al-Yemeni Department of Botany University of Peshawar Department of Botany&Biodiversity Conservation University of Swat Department of Botany&Microbiology King Saud University

Objective:To determine the present status of plant communities and their possible association with the habitat in Malam Jabba,Swat,***:A study on the phytoecology was conducted in various ecologically important sites of Malam Jabba,Swat,Pakistan from 2002 to *** altitude of these sites ranged from 1200 m to.1200 *** method was used for evaluation of plants communities and the data on these attributes was converted to relative values. The plant communities were named after 3 leading species with highest importance values. Biological spectrum of the flora based on the life form was prepared by following Raunkiar's life form ***:The floristic composition and structure of the study area were found to be 200 species belonging to 75 ***,Lamiaceae and Poaceae were important families in the study *** biological spectrum showed that therophytic and hemicrytophytic life form and micro-nonophyllous leaf sizes were dominant in the *** air and soil temperatures were decreasing with increasing *** the air and soil temperatures were relatively higher in south slopes than on the northeast *** vegetation analysis of the area indicated eleven plant communities around the *** present vegetation is the relics of moist temperate coniferous forest in the *** communities reflect highly deteriorated conditions. Both the structure and composition of the surrounding vegetation were associated with the types of ***:The conservation of the remaining populations of the reported communities will be best achieved by proper time of sustainable *** is only possible with the participation of local communities.

关键词： Plant communities Altitudinal variation Conservation slopes Biological spectrum Climatic conditions Phytoecological evaluation Vegetation Floristic appraisal Phytoecology Composition

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The Impact of Livestock Grazing on Soil Characteristics in Mount Kilimanjaro, Tanzania

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Journal of Geoscience and Environment Protection 2015年第9期3卷 24-37页

作者： Cosmas Mligo Department of Botany University of Dar es Salaam Dar es Salaam Tanzania

Livestock grazing is an anthropogenic disturbance on the soil properties in montane forests of the northern slopes of Mount Kilimanjaro. It was determined the effect of livestock grazing on SOC, N, CEC, SAS, SFD and P in the montane forest. Forty plots were randomly established for collection of soil samples. Data showed livestock grazing decreased the accumulation of SOC and consequently negatively affected the natural pattern of N, P, SFD, CEC and SAS. An opposing pattern of available soil phosphorus was interpreted that the nutrient pool retained in plant tissues particularly in the long-lived trees, which were absent in heavily grazed area. The observed positive correlation between SOC with TN and CEC implies the livestock grazing impacts on the former negatively affected the later soil parameters. Low fungal density in degraded parts of the montane forest indicates that they are sensitive to the current land use change. Based on the observation from this study, it can be regarded that excessive livestock grazing has a long-term negative ramification for soil conservation in montane forest. An important decision has to be sought off with regard to the conservation management of soil characteristics of the montane forest in Kilimanjaro Mountain.

关键词： Livestock Grazing Montane Forest Northern slopes Kilimanjaro Soil

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High-Order FEM Formulation for 3-D Slope Instability

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Applied Mathematics 2013年第5期4卷 8-17页

作者： Tiwari Ram Chandra Bhandary Netra Prakash Yatabe Ryuichi Geo-Disaster Laboratory Graduate School of Science and Engineering Ehime University Matsuyama Japan Graduate School of Science and Engineering Ehime University Matsuyama Japan

High-order finite element method (FEM) formulation also referred to as spectral element method (SEM) formulation is currently implemented in this paper for 3-dimensional (3-D) elasto-plastic problems in stability assessment of large- scale slopes (vegetated and barren slopes) in different instability conditions such as seismic and saturation. We have reviewed the SEM formulation, and have sought its applicability for vegetated slopes. Utilizing p (high-order polynomial degree or spectral degrees) and h (mesh operation for quality meshing in required elemental budgets) refining techniques in the existing FEM, the complexity of problem domain can be well addressed in greater numerical stability. Unlike the existing FEM formulation, this high-order FEM employs the same integration and interpolation points to achieve a progressive response of the instability, which drastically reduces the computational costs (formation of diagonalized mass matrix) and offers significant benefits to slope instability computations for serial and parallel implementations. With this formulation, we have achieved the following three qualities in slope instability modeling: 1) geometric flexibility of the finite elements, 2) high computational efficiency, and 3) reliable spectral accuracy. A sample problem has also been presented in this paper, which has accommodated all aforesaid numerical qualities.

关键词： Finite Element Method Spectral Element Method Slope Instability Vegetated and Barren slopes Parallel Algorithm

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Cam-Clay Models Using Castem 2000<sup>©</sup>and Plaxis<sup>©</sup>for the Study of the Slope Stability of the “Corniche Ouest” of the Dakar Peninsula (Senegal, West Africa)

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Geomaterials 2011年第2期1卷 51-58页

作者： Meissa Fall Serigne Sam Samb Mapathé Ndiaye Oustasse A. Sall Fatou Samb 不详

The stability of the natural slopes of the “Corniche Ouest” of Dakar Capital was intensively researched by previous [1] in [2] and recent studies [3]. Soils near the surface consist of weathered lateritic cuirass, silt and marl that have been intensively altered and fractured. Below these altered layers are limestones that are interbedded with other thin volcanic layers. Prior to the 1950s the area had been less urbanized. In the 1950s demand for habitations and administrative offices led to the development of the area but, no drainage system was available. In 1984 the area began moving down slope toward the ocean. Rates of movement were the fastest several months after the end of the rainy season and the slowest during the dry season. In the next years the earthflow moved as much as some meters, but in the processes the expensive homes and administrative buildings built became uninhabitable. Movement was caused by a combination of wave erosion along the coast removing some the mass resisting flow, added water due to the disposal of wastes, watering of lawns, and rainfall causing the clays to expand and weaken, and by the added weight of development on top of the flow. The first investigations, due to a lack of geotechnical information describe a stable area even though it was observed cracks and failure in habitations. The main results obtained were specially obtained by analytical techniques of slices. It is well known that the mechanical response of a solid mass of soil depends primarily on the laws of behavior which were affected to him. The Cam-Clay model is used with two comparative numerical codes such as Castem 2000?, a non commercial code and Plaxis 7.2? so as to compare the mechanical response of the slopes. The models of Cambridge are founded as simple theory and use only some soil mechanical parameters easy to determine. The results are founded highly different from a code to another, but they attest all that the system described is non stable. Otherwise

关键词： Corniche Ouest Stability Numerical Codes Cam Clay Movements Natural slopes

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Impact of a Low Severity Fire on Soil Organic Carbon and Nitrogen Characteristics in Japanese Cedar Soil, Yamagata Prefecture, Japan

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Open Journal of Forestry 2017年第2期7卷 270-284页

作者： Felix Seidel M. Larry Lopez C Georg Guggenberger Yoshihiro Nobori Faculty of Agriculture Yamagata University Yamagata Japan Institute of Soil Science Leibniz Universit&#228t Hannover Hannover Germany

Slash and burn practices are widely used around the globe with different degrees of success which are mostly related to the impact of fire on soil properties. In Japan slash and burn practises, known as Yakihata, have a long history and are still used in Yamagata Prefecture today. The purpose of this study was to determine the impact of a low severity controlled fire underneath Japanese cedar (Cryptomeria japonica) on brown forest soil (Cambisol). Japanese Cedar is the dominant species among plantations in Japan. We measured organic carbon and nitrogen content as well as changes in carbon (δ13C) and nitrogen (δ15N) stable isotope composition in a steep west facing slope under heavy precipitation (~2600 mm/a) and heavy snowfall (~3 to 4 m/a). The accumulation of Ctotal and Ntotal at the bottom of the slopes was remarkably higher at the slash and burned site than in the control forest site. After slash and burn δ15N isotopes in the slope in general became significantly lighter than in the control forest while the δ13C did not show any significant difference between the two sites except at the bottom of the slopes where δ13C was heavier in the forest. The results show that Ctotal and Ntotal values as well as the isotopes ratios of C and N change with decreasing elevation in the forest as well as in the burned site being consistent with leaching and erosion. The changes in soil nitrogen and carbon isotopes at the bottom of the slope appear to be related to the transport of material with different isotopic composition from the upper slope. The effect of the low severity fire (as part of the slash and burn practice) on soil organic carbon and nitrogen movement was enhanced by the steepness of the slopes and the high precipitation of Shonai region.

关键词： High Precipitation Japanese Cedar Forest Soil Low Severity Fire Stable Isotopes Steep slopes

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D-InSAR Analysis of Sentinel-1 Data for Landslide Detection in Northern Morocco, Case Study: Chefchaouen

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Journal of Geoscience and Environment Protection 2020年第7期8卷 84-103页

作者： Azizi Bouchra Hakdaoui Mustapha Raji Mohammed Laboratory of Applied Geology Geomatics and Environment Hassan II University of Casablanca Faculty of Sciences Ben M’sik Casablanca Morocco

Land surface displacement caused by landslides is among the most damaging phenomena in northern Morocco. In this paper, we measure ground deformation in the Chefchaouen area which is a zone characterized by geological formations and structurally complex losses that promote instability (landslide, mudflow, block falls, etc.) leading to slow to extremely slow deformation phenomena, which require an interferometric study, using the DinSAR (differential interferometric synthetic Aperture Radar) technique with sentinel 1 images in bance C, which is a powerful tool for the detection and analysis of interferences and monitoring of ground deformations. We worked on four areas of the study area. Its points are provided by the direction of the roads, which generates Interferograms and then deformation maps with precision in mm/year.

关键词： Landslides slopes SAR DInSAR Interferometric Synthetic Aperture Radar Sentinel 1

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Slope Stability Evaluations by Limit Equilibrium and Finite Element Methods Applied to a Railway in the Moroccan Rif

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Open Journal of Civil Engineering 2012年第1期2卷 27-32页

作者： Khadija Baba Lahcen Bahi Latifa Ouadif Ahmed Akhssas 3GIE Laboratory Mohammadia Engineering School Mohammed V-Agdal University Rabat Morocco

Since 1930, the analysis of slope stability is done according to the limit equilibrium approach. Several methods were developed of which certain remain applicable because of their simplicity. However, major disadvantages of these methods are (1) they do not take into account the soil behavior and (2) the complex cases cannot be studied with precision. The use of the finite elements in calculations of stability has to overcome the weakness of the traditional methods. An analysis of stability was applied to a slope, of complex geometry, composed of alternating sandstone and marls using finite elements and limit equilibrium methods. The calculation of the safety factors did not note any significant difference between the two approaches. Various calculations carried out illustrate perfectly benefits that can be gained from modeling the behavior by the finite elements method. In the finite elements analysis, the shape of deformations localization in the slope is nearly circular and confirms the shape of the failure line which constitutes the basic assumption of the analytical methods. The integration of the constitutive laws of soils and the use of field’s results tests in finite elements models predict the failure mode, to better approach the real behavior of slope soil formations and to optimize its reinforcement.

关键词： Conventional Methods Finite Elements Safety Factor slopes Stability

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Robust control of farm tractors on variable sloped terrains based on sliding-mode observers

Robust control of farm tractors on variable sloped terrains ...

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第三十九届中国控制会议

作者： Xuewei Sun Hongliang Yuan College of electronics and information engineering Tongji university

This paper considers the problem of motion control of farm tractors on sloped terrains. In reality, farm tractors often operate on sloped agricultural fields, especially in China’s hilly north-eastern provinces. In such scenarios, many tractors using GNSS navigation systems have shown deterioration in control accuracy. Existing researches mostly studied the control problem of tractor motion under the assumption of flat surface and often with a kinematic model. However, when the lateral gravitational force kicks in, these assumptions become no longer valid. It is necessary to deal with the additional lateral force at force-level, and to achieve this. The main contribution of this paper is to establish a dynamic tractor model on sloped terrains and develop a robust control framework based on sliding-mode observers. The lateral gravitational force is treated as a slowly varying disturbance at the vehicle’s lateral direction. Then a sliding-mode observer is designed to reconstruct the lateral disturbances. Finally, the H∞robust controller based on linear matrix inequality（LMI） approach is designed to attenuate the influence from unknown sloped terrains and improve the lateral offset of the tractor motion. Simulation results verified the effectiveness of the proposed method and showed superior performance than LQR controllers.

关键词： Tractor Dynamic model Sliding mode observer H∞ control Lateral attitude control slopes

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Study on Snow Line in the Tianshan Mountains Based on MODIS Image

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Asian Agricultural Research 2015年第8期7卷 60-63页

作者： Xuefei SONG Liancheng ZHANG Liequn HU Aksu Meteorological Bureau College of Geography Science and Tourism Xinjiang Normal University Urumqi Meteorological Satellite Ground Station of China Meteorological Administration

Using MOD10A1,temperature and precipitation of 21 meteorological observatories and HJ-1 / CCD data from July to September during 2002- 2013,this paper takes the Tianshan Mountains as the study area to analyze the space distribution characteristics of snow line and its influencing factors. The results show that the snowline distribution of southern and northern slopes of the Tianshan Mountains is that it is high in the south and east but low in north and west; the snowline of southern slope is sparse and there is a small spatial gradient change; the snow line is dense in the middle of northern slope,and the spatial gradient change is not large. Through the analysis of the whole study area,it is found that the correlation coefficient between snow line altitude and temperature is 0. 159,and the partial correlation coefficient between them is- 0. 212; the correlation coefficient between snow line altitude and precipitation is- 0. 668,and the partial correlation coefficient between them is- 0. 676. Precipitation is the dominant factor that affects the distribution of snow line of southern and northern slopes of the Tianshan Mountains.

关键词： Southern and northern slopes of the Tianshan Mount

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