Model Test of Sand Restraining Force on Pipeline     

Zhang Jianguo Yan Chi Yan Shuwang Lecturer  Dept. of Hydraulic Eng.  Tianjin University  Tianjin Associate Professor  Dept. of Hydraulic Eng.  Tianjin University  Tianjin Professor  Dept. of Hydraulic Eng.  Tianjin University  Tianjin 《中国海洋工程》1996,(1)

This paper describes the model tests for determining the axial friction and the lateral resistance of sand to pipeline by using fine sand and prototype pipeline, and the calculation method based on limit analysis theory is verified. The effect of cyclic loading is considered in the test.  相似文献   

Water equivalent method for city phytostructure of Indonesia     

G. Samudro B. Eng.  M. Eng.  S. Mangkoedihardjo B. Eng.  M.Sc.  E.S.  Ph.D. 《International Journal of Environmental Science and Technology》2006,3(3):261-267

This paper proposed a simple method and rapid to carry out for organizing city phytostructure. Carbon dioxide sequestration was addressed and referred to population number instead of city area. The unit storage of carbon dioxide, which was nothing less than greenspace area, was determined using equivalent method of determining unit storage of water. For various population number (P) of city area in Indonesia, the greenspace unit (GU) was 29P^?0.3 ? 3.2, and the greenspace area (GA) was 29P⁰⁷–3.2P. Greenspace distribution was preferably on wetlands, river lines, top ground level, and north south direction.  相似文献   

DARCY'S COEFFICIENT OF PERMEABILITY AS SYMMETRIC TENSOR OF SECOND RANK     

A. C. LIAKOPOULOS Dr. Eng. 《水文科学杂志》2013,58(3):41-48

Synopsis

The dynamic equation of motion that governs the laminar flow of water through soils is the empirical equation of Darcy. According to Darcy's equation the velocity of the flowing water is proportional to the hydraulic gradient under which the water is flowing, with the constant of proportionality being the coefficient of permeability. The interesting question arising is whether or not the coefficient of permeability is a scalar quantity (having only a magnitude) or a vector (having both magnitude and direction). It is proved, in the present paper, that the permeability coefficient is neither a scalar nor a vector but a symmetric tensor of second rank. The fact that the permeability tensor is symmetric gives rise to great simplifications and permits a simple graphical construction of the tensor ellipsoid. Having the tensor ellipsoid, the determination of the direction at which the water will flow under a known imposed hydraulic gradient can be found graphically. In case of isotropic soils (the permeability coefficient has the same value along any direction) the ellipsoid reduces to a sphere and the tensor becomes a scalar. In the general case of anisotropic soils the permeability tensor is an entity with nine elements, six of which are independent representing pure extension or contraction along the three principal coordinate axes, thus transforming the permeability sphere into an ellipsoid and vice versa. It should be noted that in anisotropic soils the only directions along which the flow takes place in the direction of the hydraulic gradient are those of the principal axes of the tensor ellipsoid.

Permeability tests were conducted on anisotropic sandstone samples taken at different directions with respect to rectangular coordinates. The permeability coefficient values plotted on a two-dimensional polar coordinate graph paper give rise to an ellipse substantiating therefore the tensor concept of the permeability coefficient. The graphical construction of the tensor ellipse and the use of it in order to obtain the direction of flow by knowing the direction of the hydraulic gradient is also shown.  相似文献   

MENTAL MAPS AND RESIDENTIAL DESIRABILITY. A SINGAPORE STUDY     

Teo Siew Eng 《Singapore journal of tropical geography》1995,15(2):171-187

This paper examines the perceptual images and residential desirability of public and private housing residents in Clementi housing estate in Singapore. Residents’ mental maps are established in terms of their levels of knowledgeability of activity nodes tied to various aspects of their lives, namely, workplaces, recreational and sports centres, shops and residential areas. The way the mental maps shape residents’ perceptions of what are desirable and non-desirable places to live in are also discussed. The paper highlights the significance of socio-economic differences, length of residence, physical proximity, levels of interaction and cultural leanings in influencing the mental maps and residential preferences of urban residents in Singapore  相似文献   

Genetic relationship of metamorphic reaction and dehydration-melting     

Fulai Liu  Qihan Shen  Yuansheng Eng  Xuechun Xu  Rui Ma 《中国科学D辑(英文版)》1998,41(1):49-56

The high-temperature and pressure experimental data of garnet, sillimantite and biotite-bearing potash feldspar gneiss (SGBG, natural block rock) has shown that metamorphic reactions between garnet and melt, and mineral assemblage evolutional features are not only controlled byP-T condition, but also genetically correlate with dehydration-melting of biotite and partial melting of felsic minerals. Combining experimental data with theoretical analyses, the genetic mechanism of metamorphic reaction and its dynamic significance have been demonstrated in the process of metamorphic evolution of khondalite series on the border of Jin (Shanxi Province)-Inner Mongolia. Project supported by the Youth Geologist Foundation of Ministry of Geology and Mineral Resources of China, the Post-docter Foundation and the National Natural Science Foundation of China (Grant No. 49572138).  相似文献   

Effects of meteorological and hydrogeological factors on gross recharge percentage at unconfined sandy aquifers with an equatorial climate     

Stephen Boon Kean Tan  Eng Ban Shuy  Lloyd Hock Chye Chua 《水文研究》2007,21(18):2493-2503

A thorough understanding of rainfall recharge processes and their controlling factors is essential for management of groundwater systems. This study investigates the effects of various meteorological and hydrogeological factors on the gross recharge percentages, the rainfall–recharge relationships and the recharge threshold values for unconfined sandy aquifers under an equatorial climate. Among the meteorological factors investigated, rainfall intensity was found to have the most significant impact on the gross recharge rate. The effects of potential evaporation rate, relative humidity and air temperature on the gross recharge percentage were significant when the vadose zone thickness is larger than 2·5 m. The recharge threshold values were found to depend strongly on the vadose zone thickness. The rainfall–recharge relationships could generally be well defined by a normal–log relationship. The rainfall–recharge relationships derived here are applicable to yield estimates of gross recharge percentages for unconfined sandy aquifers under an equatorial climate, using rainfall intensity and vadose zone thickness as input variables. In this study, a theory was developed and validated to provide physical explanations for the observations, based on the residence time of the percolated rainwater within the vadose zone. Among the soil hydraulic parameters tested, porosity and saturated hydraulic conductivity were found to have the most pronounced effects on the gross recharge percentage. Utilizing the sensitivity results and the theory derived, an approach was developed for extending the application of the derived rainfall–recharge relationships to other sand textures. The approach was found to be capable of producing rough and fast estimations of gross recharge percentage for other sand textures. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

METEOROLOGICAL DATA REQUIRED IN THE HYDROLOGICAL SERVICE     

Dr. Eng. Julian LAMBOR 《水文科学杂志》2013,58(2):44-47

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Substrate inhibition kinetics of phenol degradation by Pseudomonas fluorescence from steady state and wash-out data     

S. E. Agarry M.Eng.  T. O. K. Audu M.Sc.  Ph.D.  B. O. Solomon M.Sc.  Ph.D. 《International Journal of Environmental Science and Technology》2009,6(3):443-450

The present study investigated the phenol utilization kinetics of a pure culture of an indigenous Pseudomonas fluorescence under steady state and non-steady state (washout) conditions. Steady states of a continuous culture with an inhibitory substrate was used to estimate kinetic parameters under substrate limitation (chemo stat operation) Pure cultures of an indigenous Pseudomonas fluorescence were grown in continuous culture on phenol as the sole source of carbon and energy at dilution rates of 0.010 - 0.20/h. Using different dilution rates, several steady states were investigated and the specific phenol consumption rates were calculated. In addition, phenol degradation was investigated by increasing the dilution rate above the critical dilution rate (washout cultivation). The results showed that the specific phenol consumption rate increased with increased dilution rate at steady state and phenol degradation by Pseudomonas fluorescence can be described by simple substrate inhibition kinetics under substrate limitation but cannot be described by simple substrate inhibition kinetics under washout cultivation. Fitting of the steady state data from continuous cultivation to various inhibition models resulted in the best fit for Haldane, Yano and Koga (2), Aiba and Teissier kinetic inhibition models. The r_smax value of 0.229 mg/mg/h obtained from the inhibition model equations was comparable to the experimentally calculated r_smax value of 0.246 mg/mg/h obtained under washout cultivation. Therefore, the biokinetic constants evaluated using these models showed good tolerance and growth of the indigenous organism.  相似文献   

Quantitative dam break analysis on a reservoir earth dam     

F. W. L. Kho B.Sc.  M.Eng.  P. L. Law M.Sc.  Sc.D.  S. H. Lai B.Eng.  M.Sc.  Ph.D.  Y. W. Oon B.Eng.  M.Eng.  L. H. Ngu B.Eng.  M.Eng.  H. S. Ting B.Eng. 《International Journal of Environmental Science and Technology》2009,6(2):203-210

Mathematical simulations on dam break or failure using BOSS DAMBRK hydrodynamic flood routing dam break model were carried out to determine the extent of flooding downstream, flood travel times, flood water velocities and impacts on downstream affected residences, properties and environmental sensitive areas due to floodwaters released by failure of the dam structure. Computer simulations for one of the worse case scenarios on dam failure using BOSS DAMBRK software accounted for dam failure, storage effects, floodplains, over bank flow and flood wave attenuation. The simulated results reviewed a maximum flow velocity of 2.40 m/s with a discharge of approximately 242 mз /s occurred at 1.00 km downstream. The maximum discharge increased from 244 m³/s (flow velocity = 1.74 m/s occurred at 8^th. km) to 263 m³/s (flow velocity = 1.37 m/s occurred at 12^th. km); about a 39% drop in flow velocity over a distance of 4.00 km downstream. If the entire dam gives way instantly, some spots stretching from 0.00 km (at dam site) to approximately 3.40 km downstream of the dam may be categorized as “danger zone”, while downstream hazard and economic loss beyond 3.40 km downstream can be classified as “low” or “minimal” zones.  相似文献   

SINGAPORE LANDSCAPE: A HISTORICAL OVERVIEW OF HOUSING CHANGE     

Teo Siew Eng  B.A.  M.A.  Ph.D.  Victor R. Savage  B.A.  M.A.  Ph.D. 《Singapore journal of tropical geography》1985,6(1):48-63

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