To see the other types of publications on this topic, follow the link: WATER CHARACTERISTIC.
Dissertations / Theses on the topic 'WATER CHARACTERISTIC'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'WATER CHARACTERISTIC.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Bacaksız, Fatih Atagündüz Gürbüz. "Evaluations of Porous Burner Characteristic Diagrams and Process Water Production Possibilities/." [s.l.]: [s.n.], 2002. http://library.iyte.edu.tr/tezler/master/enerjimuh/T000152.rar.
Full text
2
周國榮 and Kwok-wing Chau. "Computation of tidal hydraulics and water quality using the Characteristic Galerkin method." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B3121213X.
Full text
3
Chau, Kwok-wing. "Computation of tidal hydraulics and water quality using the Characteristic Galerkin method /." Hong Kong : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19738286.
Full text
4
Mohd, Tadza Mohd Yuhyi. "Soil-water characteristic curves and shrinkage behaviour of highly plastic clays : an experimental investigation." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/55093/.
Full textAbstract:
This thesis experimentally investigated the changes in the water content and the void ratio of initially slurried highly plastic clays under zero applied stress during the drying process, changes in the water content of compacted unsaturated clay specimens during the wetting process under zero applied stress for laterally confined and free swelling conditions, and the wetting behaviour of heavily compacted bentonite specimens under confined condition. In total three clays were used, namely MX80 bentonite, Yellow bentonite, and Speswhite kaolin. Several laboratory techniques, namely centrifuge, axis-translation, vapour equilibrium, osmotic and chilled-mirror dew-point techniques were used to establish the suction-water content soil-water characteristic curves (SWCCs). The shrinkage paths of the clays were established from Clod tests and wax method. The suction-water content SWCCs in conjunction with the Clod test results enabled establishing the suction-degree of saturation SWCCs and determination of the air-entry values (AEVs). The AEVs of the clays were also determined based on the chemical analyses of Polyethylene Glycol (PEG) solutions and the applied suctions in the osmotic tests. Degradation of PEG molecules and semipermeable membranes were studied using Fourier Transform Infrared (FTIR) spectroscopy and Atomic Force Microscopy (AFM), respectively. Isochoric (constant volume) swelling pressure tests were carried out on compacted bentonite specimens using deionised water. Additionally, a newly developed suction controlled oedometer was used to study the swelling pressure and the water uptake capacities of heavily compacted bentonites under confined conditions. Microstructural changes of compacted bentonites were studied using Environmental Scanning Electron Microscope. X-Ray Diffraction technique was used to monitor the changes in the c-axis spacing of clay specimens equilibrated at several applied suctions. Applications of the Gouy-Chapman diffuse double layer theory and the van der Waals attractive pressure theory in predicting the drying and wetting suction- water content SWCCs were explored. One-dimensional wetting model (Richard's equation) was used to evaluate the elapsed time versus water content relationships for the clays. Chemical analyses of PEG solutions after the osmotic tests showed a clear lack of equalisation of the osmotic suctions due to the expelled and the retained salts on either side of semipermeable membranes. A majority of the salts were found to be retained within the clays during the osmotic tests. The AEVs of the clays determined based on the suction-degree of saturation SWCCs and that from the total suction equilibrium in the osmotic tests were found to be similar. The FTIR studies did not indicate any degradation of PEG molecules. The AFM studies of membranes revealed alterations of the pore-size during the tests that possibly lead to an intrusion of PEG into the bentonite specimens. Both qualitative and in some cases quantitative agreements were noted between the experimental suction-water content SWCCs and those predicted from the physico-chemical theories.
5
AHMED, AATIF. "EXPERIMENTAL STUDY ON WETTING SOIL WATER CHARACTERISTIC CURVE OF SAND WITH MIXTURE OF BENTONITE CLAY." Thesis, DELHI TECHNOLOGICAL UNIVERSITY, 2021. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18888.
Full textAbstract:
Soil-water characteristic curve (SWCC) also known as water retention curve is an
integral part of unsaturated soil mechanics. SWCC is a constitutive relation in
unsaturated soil mechanics where soil suction is related to water content. Wetting
SWCCs were determined for different sand-bentonite clay mixtures. With the help of
the Van-Genuchten equation, acquired test data were fitted. Wetting SWCC can be
related to flow of water through unsaturated zones of soil from the groundwater table to
the ground surface. Negative column test was employed to determine SWCC since it is
fairly simple and simulates the actual field conditions. In the present paper, different soil
samples, where sand is mixed with varying proportions of bentonite clay are considered,
for determining wetting SWCC. Finer the soil particle, higher will be the soil suction for
a given water content. Hence, as the content of clay increases, SWCC slightly shifts
towards the right, indicating the increment in soil suction. In turn, water entry
value(WEV) also shoots up.
6
van, Quang Pham. "Soil formation and soil moisture dynamics in agriculture fields in the Mekong Delta, Vietnam conceptual and numerical models." Licentiate thesis, KTH, Land and Water Resources Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10508.
Full textAbstract:
Previous studies of agricultural conditions in the Mekong Delta (MD) have identified soil compaction as an obstacle to sustainable production. A conceptual model for soil formation was presented to demonstrate the link between soil hydrology and plant response. Detailed studies of soil moisture dynamics in agricultural fields were conducted using a dynamic process-orientated model. Pressure head and water flow were simulated for three selected sites during a year for which empirical data were available. Daily meteorological data were used as dynamic input and measured pressure head was used to estimate parameter values that satisfied various acceptance criteria. The Generalised Likelihood Uncertainty Estimation (GLUE) approach was applied for calibration procedures with 10,000 runs, each run using random values within the chosen range of parameter values. To evaluate model performance and uncertainty estimation, re-sampling was carried out using coefficient of determination (R2) and mean error (ME) as the criteria. Correlations between parameters and R2 (and ME) and among parameters were also considered to analyse the relationship of the selected parameter set in response to increases/decreases in the acceptable simulations. The method was successful for two of the three sites, with many accepted simulations. For these sites, the uncertainty was reduced and it was possible to quantify the importance of the different parameters.
7
Cuceoglu, Faik. "An Experimental Study on Soil Water Characteristics and Hydraulic Conductivity of Compacted Soils." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73673.
Full textAbstract:
The importance of applying unsaturated soil mechanics concepts to geotechnical engineering design has been widely recognized. Soil water characteristic curve (SWCC) and hydraulic conductivity function (HCF) are vital soil properties that govern engineering behavior of unsaturated soils. In this study, a transient water release and imbibitions method (TRIM) is used to measure the SWCC and HCF under drying and wetting states, which accommodates integrated experimental and modeling techniques. The results of saturated hydraulic conductivity tests through flexible wall method are then used as input parameters for simulating experimental data. In general, the model provides a satisfactory fit to experimental data.
Soil water characteristic curves (SWCCs) and hydraulic conductivity functions (HCFs) are presented for a variety of soils that were prepared at different molding water contents and compactive efforts. The influences of dry density, molding water content, and hysteresis have been investigated. Dry density affects soil-water characteristic in terms of its air-entry value (AEV), rate of drying, and size of the hysteresis loop. The test results indicate that the SWCC and HCF obtained in terms of volumetric water content is more sensitive to the changes in dry density than molding water content. Based on cohesive soil results, some statistical relations are proposed to estimate wetting-path SWCC and HCF parameters from more easily measured drying curves. Changes in the van Genuchten's fitting parameters and residual volumetric water content are investigated for both drying and wetting conditions, with changes in the kaolin clay content.Master of Science
8
Kaewsaiha, Ploysai. "Characteristic properties of strongly ionic amphiphilic diblock copolymers and their self-assembly at the air/water interface." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136245.
Full text
9
Rogers, Maile Anne. "Water Vapor Movement in Freezing Aggregate Base Materials." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4013.
Full textAbstract:
The objectives of this research were to 1) measure the extent to which water vapor movement results in water accumulation in freezing base materials; 2) evaluate the effect of soil stabilization on water vapor movement in freezing base materials; 3) determine if the corresponding changes in water content are sufficient to cause frost heave during winter; 4) determine if the corresponding changes in water content are sufficient to cause reductions in stiffness during spring; 5) evaluate relationships between selected material properties, freezing conditions, and the occurrence and impact of water vapor movement; and 6) numerically simulate heat and water movement in selected pavement design scenarios. The research involved extensive laboratory and field testing, statistical analyses, and numerical modeling. The results of the laboratory testing, which included gradations, Atterberg limits, soil classifications, specific gravity and absorption values, electrical conductivity values, moisture-density relationships, soil-water characteristic curves, moisture-stiffness curves, hydraulic conductivity values, and frost susceptibility assessments, were used to characterize each material and enable subsequent statistical analyses. Testing of both treated and untreated materials enabled investigation of a wide variety of material properties. The results of the field testing, which included temperature, moisture content, water potential, elevation, and stiffness data over time, provided the basis for comparing pavement sections with and without capillary barriers and established the framework for numerical modeling. In a pavement section with a capillary barrier underlying the base layer, water vapor movement from the subgrade through the capillary barrier may be expected to increase the water content of the base layer by 1 to 3 percent during a typical winter season in northern Utah for base materials similar to those studied in this research. During winter, cold temperatures create an ideal environment for water vapor to travel upward from the warm subgrade soil below the frost line, through the capillary barrier, and into the base material. Soil stabilization can lead to increased or decreased amounts of water vapor movement in freezing base materials depending on the properties of the stabilized soil, which may be affected by gradation, mineralogy, and stabilizer type and concentration. Accumulation of water from long-term water vapor movement into frost-susceptible base materials underlain by a capillary barrier can lead to frost heave of the base layer as it approaches saturation, as water available in the layer can be redistributed upwards to create ice lenses upon freezing. However, the incremental increase in total water content that may occur exclusively from water vapor movement during a single winter season in northern Utah would not be expected to cause measurable increases in thaw weakening of the base layer during spring. Because water in a base layer overlying a capillary barrier cannot drain until nearly reaching positive pore pressures, the base layer will remain indefinitely saturated or nearly saturated as demonstrated in this research. For materials similar to those studied in this research, potentially important material properties related to the occurrence of water vapor movement during freezing include dry density, percent of material finer than the No. 200 sieve, percent of material finer than 0.02 mm, apparent specific gravity, absorption, initial water content, porosity, degree of saturation, hydraulic conductivity, and electrical conductivity. The rate at which water vapor movement occurs is also dependent on the thermal gradient within the given material, where higher thermal gradients are associated with higher amounts of water vapor movement. The numerical modeling supported the field observations that the capillary barrier effectively trapped moisture in the overlying base material, causing it to remain saturated or nearly saturated throughout the monitoring period. Only non-frost-susceptible aggregate base materials should be specified for use in cold climates in conjunction with capillary barriers, and the base material in this case should be assumed to remain in a saturated or nearly saturated condition during the entire service life of the pavement. Further study is recommended on water vapor movement in freezing aggregate base materials.
10
Khoza, Samukelisiwe Nozipho Purity. "Characteristic behaviour of pebble bed high temperature gas-cooled reactors during water ingress events / Samukelisiwe Nozipho Purity Khoza." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8706.
Full textAbstract:
The effect of water ingress in two pebble bed high temperature gas-cooled reactors
i.e. the PBMR-200 MWthermal and the PBMR-400 MWthermal were simulated and
compared using the VSOP 99/05 suite of codes.
To investigate the effect of this event on reactivity, power profiles and thermal
neutron flux profiles, the addition of partial steam vapour pressures in stages up to
400 bar into the primary circuit for the PBMR-400 and up to 300 bar for the PBMR-
200 was simulated for both reactors. During the simulation, three scenarios were
simulated, i.e. water ingress into the core only, water ingress into the reflectors only
and water ingress into both the core and reflectors. The induced reactivity change
effects were compared for these reactors.
An in-depth analysis was also carried out to study the mechanisms that drive the
reactivity changes for each reactor caused by water ingress into the fuel core only,
the riser tubes in the reflectors only and ingress into both the fuel core and the riser
tubes in the reflectors.
The knowledge gained of these mechanisms and effects was used in order to
propose design changes aimed at mitigating the reactivity increases, caused by
realistic water ingress scenarios. Past results from simulations of water ingress into
Pebble Bed Reactors were used to validate and verify the present simulation
approach and results. The reactivity increase results for both reactors were in
agreement with the German HTR-Modul calculations.Thesis (MSc (Engineering Sciences in Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013
11
Thakur, Anshuman Bramhanand. "Determination of diffusion coefficient through laboratory tests and analytically validating it using empirical relations for unsaturated soils." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2713.
Full textAbstract:
Soil suction is one of the most important physical variables affecting the soil engineering
behavior, moisture content. Suction has a major controlling influence on soil shear strength. The
moisture diffusivity properties of unsaturated properties of soils exert a critical influence on the
depth to which seasonal variations of moisture and suction at the ground surface extend into the
soil mass. Hence, a study of moisture diffusion coefficient is pivotal.
In this research the drying test originally proposed by Mitchell (1979) has been validated
by back calculating the moisture diffusion values using the empirical relation established by
Lytton (2003).
The non-linear flow through unsaturated soils has been simplified to a linear problem for
simplicity in this study. Owing to this simplification, certain refinements have therefore been
applied in the determination of diffusion coefficient. Thermocouple psychrometer was used to
measure the soil suction along the length of the sample and at different times in the laboratory.
Initial suction measurements were done using the filter paper test. Curve fitting procedure
established by (Aubeny and Lytton, 2003), has been used for the determination of the diffusion
coefficient. Analytical validation of the moisture diffusion coefficient, required coefficient of
permeability, ??k??, slope of suction water characteristic curve ??S?? and air entry value ??ho?? as the
major input parameters.
Mitchell (1979) assumed the value of ??ho?? to be 100 cm. In this research air entry value,
??ho?? has been re-evaluated and it comes out to be higher than the pre estimated value. The value
of slope of suction water characteristic curve, ??S?? obtained from pressure plate tests, compares
well to the empirical equation of Lytton (2003).
The results of moisture diffusion coefficient obtained from the empirical equation come
out in the same range as obtained from the refined Mitchell??s (1979) drying test. The refinements
includes introduction of constant temperature environment. Owing to the least variation in
temperature, more reliable and reproducible data was obtained.
The range of moisture diffusion coefficient, ??-values obtained from empirical equation,
comes out to be coherent with the laboratory data. Hence, it can be concluded that the research
was successful.
12
Nguyen, Xuan Huan, Nam Anh Tran, Thi Thuy Hang Nguyen, Thi Tuyet Nhung Dao, and Van Thanh Nguyen. "Nanosilica synthesis and application for lead treatment in water." Technische Universität Dresden, 2018. https://tud.qucosa.de/id/qucosa%3A33297.
Full textAbstract:
Lead is a naturally occurring element that has high atomic weight (207u) and density (11.3 g/cm3). Their multiple industrial, domestic, agricultural, medical and technological applications have led to their wide distribution in the environment, raising concerns over their potential effects on human health and the environment. At present, extensive application of nanosilica in environmental
pollution treatment has led to the development of silica extraction methodologies out of various chemical and waste products. In this study, nanosilica is synthesized by sol-gel method from tetraethoxysilane (TEOS) with base catalysts and volumetric ratio TEOS/C2H5OH/H2O/NH4OH: 5/30/1/1 and identified characteristics by some modern techniques such as Energy-dispersive Xray
spectroscopy (EDX), Fourrier Transformation Infrared (FTIR) and X-ray diffraction (XRD), Scanning electron micrograph (SEM), field emission scanning electron microscopy (FESEM). The results showed that the prepared SiO2 nanoparticles were amorphous phase with the average size about 60-100 nm and can be used as an immediately utilization for lead treatment. At the pH of 5, shaking within 1 hours with speed 150rpm/min, lead treatment efficiency is 96.17% for initial Pb2+
concentration 10 mgPb2+/L. Maximum adsorption concentration Qmax = 30.3mg/g, and adsorbent and adsorbate constant b = 0.868 L/g. Therefore, extracted nanosilica from TEOS has high lead treatment efficiency. In addition, synthesis nanosilica from rice husk with similar characteristics is a new research approach to improve application and economic value of the material.Chì là nguyên tố tự nhiên có khối lượng nguyên tử cao(207 đvC), tỉ trọng lớn (11,3 g/cm3) và được ứng dụng phổ biến trong công nghiệp, nông nghiệp, sinh hoạt, y tế và công nghệ. Việc sử dụng rộng rãi chì trong nhiều lĩnh vực làm tăng mối quan ngại về tác động tiềm tàng của chúng đối tới sức khỏe con người và môi trường. Hiện nay việc áp dụng rộng rãi nanosilica vào xử lí ô nhiễm môi trường đã và đang dẫn đến sự phát triển của các phương pháp tách chiết silica từ hóa chất và các phế phụ phẩm. Trong nghiên cứu này, nanosilica được tổng hợp bằng phương pháp sol-gel từ tetraetoxysilan (TEOS) với xúc tác bazo theo tỷ lệ thể tích TEOS/C2H5OH/H2O/NH4OH là 5/30/1/1 và xác định các đặc tính bằng một số kỹ thuật hiện đại như phổ tán sắc năng lượng tia X (EDX), quang phổ hồng ngoại (FTIR) và nhiễu xạ tia X (XRD), kính hiển vi điện tử quét (SEM), kính hiển vi điện tử quét phát xạ trường (FESEM). Kết quả cho thấy các hạt nano SiO2 tách chiết được có pha vô định hình với kích thước trung bình khoảng 60-100 nm và được sử dụng trực tiếp cho xử lí chì. Tại điều kiện pH=5, lắc trong 1 giờ với tốc độ 150 vòng/phút, hiệu quả xử lý chì đạt 96,17% đối với nước nhiễm kim loại chì có nồng độ ban đầu là 10mgPb2+/L. Lượng hấp phụ cực đại Qmax = 30,3mg/g; hằng số đặc trưng của chất hấp phụ và chất bị hấp phụ b = 0,868L/g. Như vậy, hiệu quả xử lý kim loại chì của vật liệu nano silica được tổng hợp từ TEOS là rất cao. Bên cạnh đó, nghiên cứu chế tạo nanosilica từ vỏ trấu với các đặc tính tương tự là một hướng đi mới giúp nâng cao tính ứng dụng và giá trị kinh tế của vật liệu.
13
Jeyisanker, Kalyani. "Analysis of Water Seepage Through Earthen Structures Using the Particulate Approach." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002783.
Full text
14
Anh, Pham Nguyet. "Study on household wastewater characterization and septic tanks' function in urban areas of Vietnam." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/192229.
Full text
15
Tu, Hongyu. "Prediction of the Variation of Swelling Pressure and 1-D Heave of Expansive Soils with respect to Suction." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32515.
Full textAbstract:
The one-dimensional (1-D) potential heave (or swell strain) of expansive soil is conventionally estimated using the swelling pressure and swelling index values which are determined from different types of oedometer test results. The swelling pressure of expansive soils is typically measured at saturated condition from oedometer tests. The experimental procedures of oedometer tests are cumbersome as well as time-consuming for use in conventional geotechnical engineering practice and are not capable for estimating heave under different stages of unsaturated conditions. To alleviate these limitations, semi-empirical models are proposed in this thesis to predict the variation of swelling pressure of both compacted and natural expansive soils with respect to soil suction using the soil-water characteristic curve (SWCC) as a tool. An empirical relationship is also suggested for estimating the swelling index from plasticity index values, alleviating the need for conducting oedometer tests. The predicted swelling pressure and estimated swelling index are then used to estimate the variation of 1-D heave with respect to suction for expansive soils by modifying Fredlund (1983) equation. The proposed approach is validated on six different compacted expansive soils from US, and on eight field sites from six countries; namely, Saudi Arabia, Australia, Canada, China, US, and the UK. The proposed simple techniques presented in this thesis are friendly for the practitioners for using when estimating the heave in unsaturated expansive soils.
16
Rosa, Ricardo Granés Tavares Duarte. "Índices de seca. Aplicação ao continente português." Master's thesis, ISA/UTL, 2011. http://hdl.handle.net/10400.5/4488.
Full textAbstract:
Mestrado em Engenharia Agronómica - Instituto Superior de AgronomiaThe Palmer Drought Severity Index (PDSI) was tested along with two indices resulting from modifying its original formulation, one concerning the replacement of the Thornthwaite equation to compute potential evapotranspiration (ETP) by the FAO Penman-Monteith method, and the other consisting in replacing the soil water balance model and the ETP computation that passes to correspond to the ETP of an olive orchard, generating a new index: the MedPDSI. A factor for the normalization of the index, the climate characteristic (K), was reviewed and the index was calibrated for each analyzed location. The Standardized Precipitation Index (SPI) for the 9 and 12 month time-scales was also tested and compared with the three variants of the PDSI. The results revealed that the modification of K improved the standardization of the PDSI and that the calibration produced statistically improved results. It was found that the MedPDSI anticipates the initiation of droughts over the original PDSI, either with ETP Thornthwaite or with ETP FAO Penman-Monteith, and tends to classify droughts more severely than the first. The use of 9 month time-scale in the SPI is the one that best relates to the PDSI, since it clearly anticipates the onset of droughts relative to the 12 month scale.
17
Roshani, Pedram. "The Effect of Temperature on the SWCC and Estimation of the SWCC from Moisture Profile under a Controlled Thermal Gradient." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31072.
Full textAbstract:
In many situations, the upper layers of soil above the ground water table are in a state of unsaturated condition. Although unsaturated soils are found throughout the world, they are predominant in arid or semi-arid regions. In these areas, the soil water characteristic curve (SWCC) which relates the water content to the matric suction could be used as key tool to implement the mechanics of unsaturated soils into the designs of geotechnical structures such as dams, embankments, pavements, canals, and foundations.
Several experimental techniques are available for determining the SWCC in a laboratory environment. However, these experimental techniques are expensive, time consuming typically requiring days or weeks, depending on the soil type, and demanding intricate testing equipment. Due to these reasons, there has been a growing interest to find other means for estimating SWCC and encourage the adoption of unsaturated soils mechanics in geotechnical engineering practice.
Several methods exist to indirectly estimate the SWCC from basic soil properties. Some may include statistical estimation of the water content at selected matric suction values, correlation of soil properties with the fitting parameters of an analytical equation that represents the SWCC, estimation of the SWCC using a physics-based conceptual model, and artificial intelligence methods such as neural networks or genetic programming.
However, many studies have shown that environmental effects such as temperature, soil structure, initial water content, void ratio, stress history, compaction method, etc. can also affect the SWCC. This means that the estimation SWCC from set of conditions may not reliably predict the SWCC in other conditions. Due to this reason, it is crucial for engineers involved with unsaturated soils to take into account all the factors that influence the SWCC.
The two key objectives of the present thesis are the development of a method based on first principles, using the capillary rise theory, to predict the variation of the SWCC as a function of temperature, as well as developing a technique for the prediction of the fixed parameters of a well-known function representing the SWCC based on basic soil properties together with the moisture profile of a soil column subjected to a known temperature gradient.
A rational approach using capillary rise theory and the effect of temperature on surface tension and liquid density is developed to study the relation between temperature and the parameters of the Fredlund and Xing (1994) equation. Several tests, using a Tempe cell submerged in a controlled temperature bath, were performed to determine the SWCC of two coarse-grained soils at different temperatures. A good comparison between the predicted SWCC at different temperatures using the proposed model and the measured values from the Tempe cell test results is achieved.
Within the scope of this thesis, a separate testing program was undertaken to indirectly estimate the SWCC of the same two coarse-grained soils from the measurement of their steady state soil-moisture profile while subjected to a fixed temperature differences. The water potential equation in the liquid and vapor phases is used to analyses the steady state flow conditions in the unsaturated soil. A good comparison is obtained for the SWCC estimated using this technique with the SWCC measured used a Tempe cell submerged in a controlled temperature bath.
The results of this study indicate that knowledge of the moisture content of a soil specimen under a constant thermal gradient and basic soil properties can be used to estimate the SWCC of the soil at the desired temperature.
18
Beyer, Matthias, Dirk Lucas, Heiko Pietruske, and Lutz Szalinski. "Two-Phase Flow Experiments on Counter-Current Flow Limitation in a model of the Hot Leg of a Pressurized Water Reactor (2015 test series)." Helmholtz-Zentrum Dresden-Rossendorf, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-216094.
Full textAbstract:
Counter-Current Flow Limitation (CCFL) is of importance for PWR safety analyses in several accident scenarios connected with loss of coolant. Basing on the experiences obtained during a first series of hot leg tests now new experiments on counter-current flow limitation were conducted in the TOPFLOW pressure vessel. The test series comprises air-water tests at 1 and 2 bar as well as steam-water tests at 10, 25 and 50 bar. During the experiments the flow structure was observed along the hot leg model using a high-speed camera and web-cams. In addition pressure was measured at several positions along the horizontal part and the water levels in the reactor-simulator and steam-generator-simulator tanks were determined.
This report documents the experimental setup including the description of operational and special measuring techniques, the experimental procedure and the data obtained.
From these data flooding curves were obtained basing on the Wallis parameter. The results show a slight shift of the curves in dependency of the pressure. In addition a slight decrease of the slope was found with increasing pressure. Additional investigations concern the effects of hysteresis and the frequencies of liquid slugs. The latter ones show a dependency on pressure and the mass flow rate of the injected water.
The data are available for CFD-model development and validation.
19
Silva, Angelita Martins da. "Banco de dados de curvas de retenção de água de solos brasileiros." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-27012006-043239/.
Full textAbstract:
A mecânica dos solos não saturados tem se tornado um importante tema de pesquisas dedicadas a entender o comportamento dos solos não saturados e otimizar sua utilização em várias obras civis. A curva de retenção de água, definida como a relação entre a sucção e a quantidade de água presente no solo, é considerada um elemento chave na interpretação do comportamento e propriedades dos solos não saturados tais como a condutividade hidráulica e a resistência ao cisalhamento. Este trabalho apresenta a estrutura de um banco de dados projetado para armazenar informações de solos brasileiros com enfoque nas características de retenção de água. O banco de dados inclui a curva de retenção e os parâmetros de ajuste das equações de van Genuchten (1980) e Fredlund & Xing (1994), assim como informações das características dos solos como índices físicos, classificações dos solos, análises granulométricas, índices de consistência e localização e estado da amostra. Além da estimativa da função condutividade hidráulica, o banco de dados oferece duas ferramentas que permitem a pesquisa rápida ou detalhada das informações e os dados armazenados podem ser mostrados na tela ou em relatórios impressosUnsaturated soil mechanics has become an important subject of research devoted to understand the behavior of unsaturated soils and optimize their use in several civil works. The soil-water characteristic curve, defined as the relationship between the suction and the amount of water present in the soil, is considered as the key in the interpretation of the behavior and properties of unsaturated soils, such as the hydraulic conductivity and the shear strength. This paper presents the structure of a database designed to store information of brazilian soils with focus in the characteristics of water retention. The database includes the retention curves and the parameters of adjusted van Genuchten and Fredlund & Xing equations and also information of soil characteristics such as physical indexes, soil classifications, particle-size analysis, consistency indexes and location and kind of used samples. Beyond the estimate of hydraulic conductivity, the database presents two search tools that allow for quick and detailed recovering of information and stored data can be displayed on screen or in printed reports
20
Vivian, Juliana Baum. "Utilização do método do papel filtro para a determinação das curvas características de um solo coluvionar não saturado contaminado com óleo diesel." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/14377.
Full textAbstract:
Para a determinação do comportamento de um solo não saturado, é necessária a identificação da sua curva característica, que representa a capacidade de armazenamento de água pelo solo em função do valor de sucção imposto. Quando este solo é submetido a algum processo de contaminação, a sua estrutura interna pode ser alterada por processos físico-químicos, modificando, por conseqüência, o seu comportamento. Esta dissertação propõe uma metodologia de ensaio para a determinação de curvas características de sucção total em um solo artificialmente contaminado com diferentes teores de óleo diesel. O programa experimental proposto consiste basicamente na realização do método do papel filtro, através da técnica sem contato entre a amostra e o papel, com algumas modificações em relação às metodologias anteriormente descritas na literatura geotécnica. Foram também executados ensaios para controle e quantificação da evaporação do contaminante ao longo do tempo, e sua possível absorção pelo papel filtro utilizado. Além disso, foram realizados ensaios para a caracterização física, mineralógica e química do solo, antes e após a adição do óleo, com o intuito de constatar as alterações causadas pela contaminação. O material estudado é constituído por sedimentos coluvionares provenientes de arenito da Formação Botucatu, sendo que sua curva característica, sem contaminação, já foi determinada em um estudo anterior, através do método do papel filtro com contato. Para possibilitar comparações entre estes resultados, foram medidos também alguns pontos em amostras não contaminadas, através da técnica proposta nesta dissertação. Estes apresentaram uma satisfatória concordância em relação à curva anteriormente ajustada. Na análise das curvas características do solo contaminado com 2%, 5%, 10% e 15% de óleo diesel, constatou-se a permanência do formato bimodal, sugerindo que a microestrutura e a macroestrutura continuam influenciando na entrada e saída de água do meio. Entretanto, foram identificadas alterações na forma da curva e na extensão dos patamares resultantes, em relação à curva característica sem contaminação, assim como as diferentes localizações dos valores de entrada de ar. Foi verificado que, conforme o aumento do teor de contaminante, há uma gradual tendência ao formato unimodal da curva característica, induzindo a um comportamento de solo tipicamente granular. Este fato foi comprovado nos resultados de microscopia eletrônica, onde se verifica que, com teores menores de óleo, a estrutura do solo encontra-se mais fechada e, à medida que este teor aumenta, a estrutura torna-se mais porosa. Os tempos de equalização para o método de ensaio proposto variaram entre 7 e 30 dias, conforme o nível de sucção da amostra. A avaliação da histerese revelou que, com o aumento do teor de contaminante, há uma pequena redução deste fenômeno. Além disso, os ensaios complementares comprovaram a existência de uma pequena porcentagem de evaporação do óleo diesel, assim como a absorção do mesmo pelo papel filtro, que se apresentou praticamente nula.The unsaturated soil behavior can be determined through its soil-water characteristic curve, which represents the capacity of the soil to store water when submitted to different suction levels. When this soil is contaminated, its internal structure can be modified according to physical and chemical processes, thus changing the initial behavior. This dissertation proposes a test methodology to determine the total-suction soil-water characteristic curves of a contaminated soil at different diesel oil contents. The experimental program consisted of using the filter-paper method without contact between the sample and the paper, but with some modifications in relation to previously studied techniques. Some control tests were also carried out to check oil evaporation and its absortion by the filter paper. Besides, the samples were submitted to physical, mineralogical and chemical characterization, before and after contamination, to verify the possible changes. The studied material is a colluvium soil, constituted basically by sandstone, from the Botucatu Formation. This soil was previously studied by the filter-paper method with contact, and its soil water characteristic curve without contamination was already known. To compare the results, the proposed test methodology was also performed with non contaminated samples, showing a satisfactory agreement with the initial curve. The soil-water characteristic curves of this soil with a diesel oil content of 2%, 5%, 10% and 15% showed a "saddle" shape, indicating that both the microstructure and the macrostructure were influenced by the entrance and exit of water through the soil. However, the shape of the curve and the extent of its plateau changed according to the level of contamination. Increasing the oil content, the curve tends to a unimodal shape, with a behavior similar to granular soils. This statement was proved by the microstruture photographs, which showed an increase of sample porosity due to the increase of oil content. The time required to reach suction equilibrium during the tests varied between 7 to 30 days, according to the initial water content of the samples. The observed hysteresis had a small reduction with the increase of oil content. The control tests proved that oil evaporation and its absortion by the filter paper were insignificant in the whole test program.
21
Tatagiba, Sandro Dan. "Crescimento inicial, trocas gasosas e status hídrico de clones de eucalipto sob diferentes regimes de irrigação." Universidade Federal do Espírito Santo, 2006. http://repositorio.ufes.br/handle/10/6579.
Full textAbstract:
Made available in DSpace on 2016-12-23T14:37:33Z (GMT). No. of bitstreams: 1
Dissertacao_Sandro.pdf: 1073612 bytes, checksum: 32d65322ff6d4ce9aa2a775f64a664fe (MD5)
Previous issue date: 2006-02-24O objetivo desse estudo foi avaliar o efeito do déficit hídrico sobre as características de crescimento: diâmetro do coleto; altura das plantas; área foliar; relação raiz/parte aérea; matéria seca de: folhas, haste e ramos, raízes e total; e as características fisiológicas das trocas gasosas (fotossíntese líquida, condutância estomática, transpiração) e potencial hídrico foliar, em seis clones de eucalipto (1, 2, 3, 4, 5 e 6) crescendo em vasos plásticos de diâmetro de 42 cm e altura de 72 cm, com aproximadamente 100 dm3, de modo a subsidiar a seleção desses materiais genéticos para estabelecimento em áreas com disponibilidade diferenciada de água no solo. Foram avaliadas algumas variáveis climáticas durante todo o período experimental, a fim determinar a condição no ambiente em estudo. As plantas cresceram nos vasos com teor de água próximo a capacidade de campo por um período de 150 dias, quando, então, foram iniciados os manejos hídricos diferenciados até o final do experimento que durou cerca de 250 dias. Os manejos hídricos aplicados foram: sem déficit - manutenção dos vasos próximo à capacidade de campo ao longo de todo o período experimental, ou seja, 250 dias; déficit 1 - corte da irrigação aos 150 dias de experimentação, durante 45 dias e posterior retomada da irrigação por mais 55 dias; déficit 2 - corte da irrigação aos 150 dias de experimentação, prolongando até o final do experimento (100 dias de déficit hídrico). O clone mais afetado pela deficiência hídrica foi o 3, apresentando menor acúmulo xiv de matéria seca total e maior redução em área foliar, provocada principalmente pela abscisão foliar. Contrariamente, os clones 1, 2, 4 foram os mais tolerantes aos efeitos do déficit hídrico, em razão de terem apresentado maior acúmulo de matéria seca total. De modo geral, o déficit hídrico promoveu a redução dos valores da fotossíntese, condutância estomática, e transpiração foliar de todos os clones. Os clones 1, 2 e 4 apresentaram os valores mais altos de potencial hídrico foliar nas plantas submetidas ao déficit hídrico ao longo das campanhas realizadas, mostrando obter mecanismos eficientes no controle de perda de água, já que apresentaram as menores taxas transpiratórias e menores valores de condutância estomática. Pressupõe-se que o aparato fisiológico destes clones permita alcançar um menor consumo de água, favorecendo a planta a suportar um período mais longo de déficit hídrico, e possibilitando uma maior conversão de CO2 atmosférico em carboidrato por período maior de tempo. O clone 3 apresentou menores valores de fotossíntese, condutância estomática e transpiração quando submetido ao déficit hídrico nas duas campanhas realizadas. O clone 6 apresentou maior transpiração no nível de manejo sem déficit e sob déficit em relação aos demais clones, sugerindo elevado consumo de água pelas plantas. Após a retomada da irrigação, todos os clones recuperaram suas taxas fotossintéticas similares às registradas pelos clones mantidos sem déficit, contribuindo para acréscimos na matéria seca total das plantas.
The objective of this study was to evaluate the effect of the deficit water on the following growth characteristics: diameter of the stem; height of the plants; foliate area; relationship root/aerial part; dry matter: of the leaves, stem and branches, roots and total; and the physiologic characteristics of the gaseous changes (liquid photosynthesis, stomatal conductance, transpiration) and leaf potential water, in six eucalyptus clones (1, 2, 3, 4, 5 and 6) growing in plastic vases of diameter of 42 cm and height of 72 cm, with approximately 100 dm3, in way to subsidize the selection of these genetic materials for establishment in areas with differentiated readiness of water in the soil. Some variable climatics were evaluated during all the experimental period, to determine the condition in the environment in studying. The plants grew in the vases with tenor of water close to the field capacity for a period of 150 days, when, then, were initiated the differentiated handlings of water until the end of the experiment that lasted about 250 days. The water handlings applied were: without deficit- maintenance of the vases near to the field capacity along the whole experimental period, in other words, 250 days; deficit 1- irrigation cutting to the 150 days of experimentation, during 45 days and subsequent retaking of the irrigation for more 55 days; deficit 2- irrigation cutting to the 150 days of experimentation, prolonging until the end of the experiment (100 days of deficit water). The most affected clone was 3, introducing smaller accumulation of matter total dry and larger reduction in foliate area, provoked mainly by foliate abscission. Contrarialy, xvi the clones 1, 2, and 4 were the most tolerant to the water deficit effects, in reason of having presented a larger accumulation of matter total dry. In general, the water deficit promoted the reduction of the values of the photosynthesis, the stomatal conductance and the transpiration of all of the clones. The clones 1, 2 and 4 presented the highest values of the leaf water potential in the plants submitted to the water deficit along the accomplished campaigns, showing to obtain efficient mechanisms in the control of losing water, since they presented the smallest transpiration rate and smaller values of stomatal conductance. It is presupposed that the physiologic apparatus of these clones allow to reach a smaller consumption of water, favoring the plant to support a longer period of water deficit , and making possible a larger conversion of at atmospheric CO2 in carbohydrate for a larger period of time. The clone 3 presented smaller photosynthesis values, stomatal conductance and transpiration when submitted to the ware deficit in the two accomplished campaigns. The clone 6 presented larger transpiration in the handling level without deficit and under deficit in relation to the other clones, suggesting high consumption of water by the plants. After the irrigation retaking, all the clones recovered their similar photosynthesis rate to the ones registered by the clones maintained without deficit, contributing to increments in the matter total dry of the plants.
22
Shrivastava, Asheesh. "Environmental Chemistry of Lake Biwa, Japan: General trend in the changes of water quality judged from the long-term variation and the characteristic distribution of nutritious elements." Kyoto University, 2010. http://hdl.handle.net/2433/120451.
Full textAbstract:
Kyoto University (京都大学)0048
新制・課程博士
博士(人間・環境学)
甲第15485号
人博第515号
新制||人||125(附属図書館)
21||人博||515(吉田南総合図書館)
27963
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授 堀 智孝, 教授 杉山 雅人, 教授 石川 尚人
学位規則第4条第1項該当
23
Bonder, Brunno Henrique. "Curvas de retenção de agua de um solo coluvionar de Campinas obtidas mediante tecnicas de laboratorio e de campo." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257682.
Full textAbstract:
Orientador: Miriam Gonçalves MiguelDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-11T22:58:54Z (GMT). No. of bitstreams: 1 Bonder_BrunnoHenrique_M.pdf: 2047878 bytes, checksum: f980b746a4148ebf1cf393fb9e4a010a (MD5) Previous issue date: 2008
Resumo: Como ponto de partida, concentra-se esta pesquisa em determinar as relações de teor de umidade (ou grau de saturação) versus o valor da sucção matricial, conhecidas por curvas características de sucção ou curvas de retenção, para o solo da camada superficial do Campo Experimental de Mecânica dos Solos e Fundações da UNICAMP. Esta camada é constituída de uma argila siltoarenosa, porosa, em condição não saturada, laterítica, colapsível e coluvionar de espessura em torno de 6,5m; resultante do alto grau de intemperismo. Na determinação das curvas utilizou-se a técnica do papel filtro, complementando a técnica de translação de eixos, já utilizada para o solo, através do Aparelho de Richards. Os procedimentos foram de secagem e de umedecimento das amostras, permitindo o estudo do fenômeno de histerese, à luz da estrutura e da composição químico-mineralógica do solo. Também foi realizado um monitoramento em campo da variação da sucção matricial ao longo de um ano, para confirmar o fenômeno da histerese que ocorre in situo As curvas de retenção de água forneceram valores de pressão de entrada de ar que variam de 1 à 5 kPa, dependendo da técnica utilizada, lembrando o comportamento de areias, e mostraram que o fenômeno da histerese ocorre de maneira mais acentuada, em solos com poros maiores. Confrontaram-se os resultados obtidos com as diferentes técnicas de realização dos ensaios e analisaram-se as diferenças entre elas.
Abstract: This research focuses in to determine the relationship of moisture content (or degree of saturation) versus the value of the suction matrix, known as soil water characteristic curve (SWCC), to the soil surface layer of the Field Experimental of Soil Mechanics and Foundation of UNICAMP. This profile consists of colluvial, lateritic, porous, on condition unsaturated and collapsible silty clay, with thickness around 6,5m and present on a clayed silt soil, residual of diabase; resulting from the high degree of weathering. To determine the curves, the techniques of filter paper and axis-translation were used, with a Richards equipment, this already used to the soil. The procedures were wetting and drying of the samples, allowing the study of the phenomenon of hysteresis, in the light of the structure and chemical and mineralogical composition of the soil. It was carried out in the field of "tracking a variation of suction matrix over a year, to confirm the phenomenon of hysteresis that occurs in situo The SWCCs supplied values of enter air ranging from 1 to 5 kPa, depending on the technique used, reminding the behaviour of sand, and showed that the phenomenon of hysteresis occurs in a manner more pronounced in soils with pores greater.' Compared the achievements of ,lhe different techniques for conducting the tests and analyzed the differences between them.
Mestrado
Geotecnia
Mestre em Engenharia Civil
24
Liu, Zhen. "Multiphysics Simulation and Innovative Characterization of Freezing Soils." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1350331910.
Full text
25
Lowry, Bonita Kristine. "Zinnia Growth and Water Use Efficiency in a Rate Study of Coconut Coir Pith and Sphagnum Peat Moss in Container Growing Substrates." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1419244167.
Full text
26
Feverharmel, Carolina. "Estudo da resistência ao cisalhamento e da condutividade hidráulica de solos coluvionares não saturados da Formação Serra Geral." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/13467.
Full textAbstract:
Esta tese apresenta um estudo sobre a resistência ao cisalhamento e a condutividade hidráulica de dois solos coluvionares não saturados situados na divisa dos estados do Rio Grande do Sul e Santa Catarina, em um dos trechos do Gasoduto Bolívia-Brasil. Esses solos são constituídos por sedimentos oriundos da Formação Serra Geral (basalto – Solo RO) e da Formação Botucatu (arenito – Solo AV). O trabalho de pesquisa realizado com esses solos tem seu enfoque dividido em duas partes principais: (1) obtenção direta da resistência ao cisalhamento e da função condutividade hidráulica em diferentes níveis de sucção, e (2) previsão indireta dessas propriedades a partir da determinação da curva característica do solo e de parâmetros geotécnicos saturados. As curvas características dos solos AV e RO, nas condições indeformada e remoldada (sem e com secagem prévia do solo), foram obtidas pelo uso combinado do método do papel filtro e da placa de sucção. Para as condições indeformada e remoldada sem secagem prévia, essas curvas exibiram um formato bimodal. A dessaturação é controlada pelos macroporos, para baixas sucções, e pelos microporos, para altas sucções. Para valores de sucção intermediários, praticamente não ocorre remoção de água do solo, devido, provavelmente, à ausência de poros com tamanho intermediário. Já as curvas características das amostras remoldadas com secagem prévia do solo tendem a apresentar um formato mais próximo do unimodal. A influência do índice de vazios inicial e da história de umedecimento e secagem no formato da curva é também discutida. A resistência ao cisalhamento dos solos estudados foi determinada em laboratório através de ensaios de cisalhamento direto convencionais e com sucção controlada. Os resultados, obtidos para amostras indeformadas e remoldadas sem secagem prévia, permitiram a determinação dos parâmetros de resistência ao cisalhamento c’, f’ e fb. Para determinação direta da função condutividade hidráulica do Solo AV foi construído um permeâmetro triaxial com controle de sucção, baseado no modelo apresentado por Huang et al. (1998). Esse equipamento foi utilizado para determinação da função condutividade hidráulica do Solo AV não saturado, em diferentes trajetórias de umedecimento e secagem. Os resultados evidenciaram que as amostras do Solo AV nas três condições de moldagem - indeformada, remoldada sem e com secagem - tendem a reproduzir o comportamento de dessaturação exibido nas curvas características. A função condutividade hidráulica apresenta inicialmente um decréscimo para sucções até 50 kPa, seguido por um valor praticamente constante, para sucções até 90 kPa.This thesis presents a study about the shear strength and hydraulic conductivity of two unsaturated colluvium soils situated at the border between the states of Rio Grande do Sul and Santa Catarina, along one of the Bolivia-Brazil Gas Pipeline stretches. These soils are constituted by sediments originated from Serra Geral (basalt – sample RO) and Botucatu formations (sandstone - sample AV). The research performed with these soils had its focus divided in two main parts: (1) direct measurements of shear strength and hydraulic conductivity function at different suction levels and (2) indirect prediction of these properties from the soil-water characteristic curves and saturated geotechnical parameters. The soilwater characteristic curves of AV and RO Samples, in undisturbed and remolded conditions (without and with previous drying), were determined with both the filter-paper technique and the suction-plate technique. The undisturbed and remolded samples without previous drying showed a bimodal shape. The desaturation is controlled by the macropores for low suction values and by the micropores, for higher values. For intermediary suctions values, practically no removal of water from the sample occurs, possibly due to the lack of intermediate pore sizes. The remolded samples with previous drying tend to present a shape close to unimodal. The influences of void ratio and the drying and wetting history in the shape of the soil-water characteristic curve are also discussed. The shear strength of the studied soils was determined with conventional and suction-controlled direct shear tests. The results obtained for undisturbed and remolded samples without previous drying allowed the determination of shear strength parameters c’, f’ e fb. For the direct measurement of hydraulic conductivity function, a flexible-wall permeameter was built, based on the model presented by Huang et al. (1998). This equipment was used for determining the unsaturated hydraulic conductivity function of Sample AV in different drying and wetting paths. The results showed that Samples AV in the three molding conditions - undisturbed and remolded without and with previous drying – reproduced the desaturation behavior showed by the soil-water characteristic curves. The hydraulic conductivity function presents initially a decrease for suctions up to 50 kPa, followed by a practically constant value, for suctions up to 90 kPa.
27
Nam, Soonkie. "Effects of Reservoir Releases on Slope Stability and Bank Erosion." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77114.
Full textAbstract:
Reservoir release patterns are determined by a number of purposes, the most fundamental of which is to manage water resources for human use. Managing our water resources means not only controlling the water in reservoirs but also determining the optimum release rate taking into account factors such as reservoir stability, power generation, water supply for domestic, industrial, and agricultural uses, and the river ecosystem. However, riverbank stability has generally not been considered as a factor, even though release rates may have a significant effect on downstream riverbank stability. Riverbank retreat not only impacts land properties but also damages structures along the river such as roads, bridges and even buildings. Thus, reservoir releases need to also take into account the downstream riverbank stability and erosion issues.
The study presented here investigates the riverbank stability and erosion at five study sites representing straight as well as inside and outside channel meander bends located on the lower Roanoke River near Scotland Neck, North Carolina. Extensive laboratory and field experiments were performed to define the hydraulic and geotechnical properties of the riverbank soils at each site. Specifically, soil water characteristic curves were determined using six different techniques and the results compared to existing mathematical models. Hydraulic conductivity was estimated using both laboratory and in situ tests. Due to the wide range of experimentally obtained values, the values determined by each of the methods was used for transient seepage modeling and the modeling results compared to the actual ground water table measured in the field. The results indicate that although the hydraulic conductivities determined by in situ tests were much larger than those typically reported for the soils by lab tests, numerical predictions of the ground water table using the in situ values provided a good fit for the measured ground water table elevation. Shear strengths of unsaturated soils were determined using multistage suction controlled direct shear tests. The test method was validated, and saturated and unsaturated shear strength parameters determined. These parameters, which were determined on the basis of results from both laboratory and field measurements, and the associated boundary conditions, which took into account representative flow rates and patterns including peaking, drawdown and step-down scenarios, were then utilized for transient seepage analyses and slope stability analyses performed using SLIDE, a software package developed by Rocscience. The analyses confirmed that the riverbanks are stable for all flow conditions, although the presence of lower permeability soils in some areas may create excess pore water pressures, especially during drawdown and step-down events, that result in the slope becoming unstable in those locations. These findings indicate that overall, the current reservoir release patterns do not cause adverse impacts on the downstream riverbanks, although a gradual drawdown after a prolonged high flow event during the wet season would reduce unfavorable conditions that threaten riverbank stability.Ph. D.
28
Novák, Jan. "Měření dynamických charakteristik zpětných armatur." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318147.
Full textAbstract:
Master thesis presents overview of existing types of check valves, their features, uses and issue called "cracking". Experimental part of this thesis focuses on the lift and swing check valves. Results of the measurement are evaluated from non-stationary flow point of view by developing and analyzing static and dynamic characteristics. This thesis takes into account losses and dynamic effects as main viewpoints. Two methods for measuring non-stationary velocities are used. Direct method called Gibson and indirect method laser doppler anemometry. Goal of the master thesis is to increase understanding of the check valves and their applicability.
29
Vosolo, David A. "Investigation on geotechnical engineering properties of coal mine spoil subjected to slaking." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/109789/1/David_Vosolo_Thesis.pdf.
Full textAbstract:
This research project has led to the development of a new approach to assess the saturated and unsaturated properties of soil material subjected to slaking. Constant saturation along with overburden pressure resulted in a larger vertical deformation ofInvestigation on geotechnical engineering properties of coal mine spoil subjected to slaking the slaking chambers; which is indicative of slaking, these results indicate that material slaking was occurring due to saturation and overburden pressure. This will have a substantial benefit to the mining operations with distinctive interest associated to safety of the mine spoil slopes, limiting failures to protect workers, equipment, and operational costs.
30
"Temperature Effect on the Soil Water Retention Characteristic." Master's thesis, 2011. http://hdl.handle.net/2286/R.I.9456.
Full textAbstract:
abstract: The importance of unsaturated soil behavior stems from the fact that a vast majority of infrastructures are founded on unsaturated soils. Research has recently been concentrated on unsaturated soil properties. In the evaluation of unsaturated soils, researchers agree that soil water retention characterized by the soil water characteristic curve (SWCC) is among the most important factors when assessing fluid flow, volume change and shear strength for these soils. The temperature influence on soil moisture flow is a major concern in the design of important engineering systems such as barriers in underground repositories for radioactive waste disposal, ground-source heat pump (GSHP) systems, evapotranspirative (ET) covers and pavement systems.. Accurate modeling of the temperature effect on the SWCC may lead to reduction in design costs, simpler constructability, and hence, more sustainable structures. . The study made use of two possible approaches to assess the temperature effect on the SWCC. In the first approach, soils were sorted from a large soil database into families of similar properties but located on sites with different MAAT. The SWCCs were plotted for each family of soils. Most families of soils showed a clear trend indicating the influence of temperature on the soil water retention curve at low degrees of saturation.. The second approach made use of statistical analysis. It was demonstrated that the suction increases as the MAAT decreases. The statistical analysis showed that even though the plasticity index proved to have the greatest influence on suction, the mean annual air temperature effect proved not to be negligible. In both approaches, a strong relationship between temperature, suction and soil properties was observed. Finally, a comparison of the model based on the mean annual air temperature environmental factor was compared to another model that makes use of the Thornthwaite Moisture Index (TMI) to estimate the environmental effects on the suction of unsaturated soils. Results showed that the MAAT can be a better indicator when compared to the TMI found but the results were inconclusive due to the lack of TMI data available.Dissertation/Thesis
M.S. Civil Engineering 2011
31
Huang, Jun-Rong, and 黃俊榮. "The Characteristic of Dipole Antenna in the water." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/57882045751645218433.
Full textAbstract:
碩士大葉大學
電信工程學系碩士班
96
The dielectric constant of antenna in the air and water is different, the dielectric constant in the air is 1, and the dielectric constant in the water is 81, in order to understand the radiation characteristics in the water, we design a dipole antenna which can radiate in the water. We simulateuse radition pattern and return loss by HFSS, and manufacture a simple dipole antenna, we measurement radiation pattern and return loss by vector network analyzer and 4-axes measurement system, we discussed the electromagnetic wave propagation effects on the different media in the water.
32
Wei-Shih, Wu, and 巫偉詩. "The Soil Water Characteristic Curves of Silty Sand." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/02371578132448030089.
Full textAbstract:
碩士建國科技大學
土木與防災研究所
101
The soil water characteristic curve (SWCC) describes the relationship between saturation and water content of soil. The matric suction is affected by water content and change the shear strength. The matric suction provides additional shear strength to stabilize unsaturated soil slope in the dry season. When rainy season comes, rainfall infiltration weakens matric suction and trigger landslide. This study perform pressure plate tests to establish SWCC and SDSWCC (stress dependent soil water characteristic curve). The silty sand (Mai Liao Sand, MLS) is used to produce testing specimen according to different fines content (FC) and relative density (Dr). Test results shows FC affect the slope of descent of SWCC when applied pressure is not over 250kPa. The SWCC tends to change slowly when specimen has higher FC. The hysteresis effect (the difference of desorption and sorption at initial state) is obvious when specimen has lower FC. The difference between SWCC and SDSWCC is that SDSWCC considers the influence of vertical loading. Because of the loading effects, SDSWCC is slightly different from SWCC for silty sand. A few tests of lateritic soil are also carried out to compare with MLS. The SWCC of lateritic soil presents a more gentle descent curve in comparison with MLS.
33
Luo, Kh-Shinn, and 羅克信. "The Characteristic of Wave Spectral Form in Shallow Water." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/05262947298949988149.
Full textAbstract:
碩士國立交通大學
土木工程研究所
83
Spectral analysis is a useful method for describing the random waves. Due to the complexity of wave mechanism, it is likely to lack of standard form for shallow water wave. In this study, we use the laboratory wave data obtained in different wave conditions to determine a generalized power spectral form of shallow water waves. From the experimental results, we find the parameter m used in Pierson-Moskowitz is only the function of relative water depth so that we have a empirical formula to determine the spectral form.For the bottom slope,our experiments take the bed slope 1:30 and 1:50.We find that the bottom slope has not obvious effect on the empirical formula. By using of bispectrum theory to judge nonlinear quantities, we find that the nonlinear component energy occupied the total energy about 15﹪when relative water depth between 0.3 and 0.05. When the relative water depth is less than 0.05, the spectral shape will become double peak types. From the results, the shape of the power spectral form becomes milder in shallow water. It is concluded that the milder shape of shallow water wave spectrum can not be completely attributed to nonlinear interaction and bottom friction.
34
Chung, Jui-Chien, and 鍾瑞謙. "Study on Water Storage Characteristic of Terraced Paddy Field." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/17420505857393677646.
Full textAbstract:
碩士國立中興大學
土木工程學系所
104
In this study, the terraced paddy field is adopted for the rainfall-runoff analysis for the water storage, regarding the importance of experimental study of terraced paddy field of the localization.This study based on paddy tank model.Try to modify the model to build paddy tank model modified of two-stage paddy tank model and three-stage paddy tank model, and did a degree of correlation in physical meaning on discussion and analysis.The model can be adjusted flexibly according to the demonstrated case of the actual outflow so as to meet the field requirement. The study uses the multi-start-Powell scheme to optimize the flow rate parameters that are used to evaluate the detention capacity of the storage facility of the water self-sustained community. The test site is located at Hsin-pu area of Hsin-chu County. This test for the terraced paddy field,total area about 7434 hectares, the total average gradient about 25°.The study uses the paddy tank model to simulate the rainfall-runoff of rainfall events.This project selected the rainfall events in experimental trraced paddy field during the year 2007-2008 years,and collected the quantitative data of rainfall.Paddy tank model by Multi-start Powell which was used to calibrate the commonality parameters of Multi-start Powell and choose two the rainfall-runoff to test commonality parameters. According to the terraced paddy field of rainfall and flow data, comparing the simulation results. The results show that the GM of the three-stage 13 par paddy tank model is 0.0209 and 14par paddy tank model is 0.0115.The R2 (Square of Pearson Correlation Coefficient) of the calculated and observed values is 0.991 for the three-stage 13par paddy tank model is 0.991 and 14par paddy tank model is 0.991, 14par paddy tank model shows an acceptable correlation and that the application of the paddy tank model to the water cycle is adequate.The result showed that modified 14 parameters of three-stage paddy tank model has better applicability on the terraced paddy field.
35
Tinjum, James Martin. "Soil water characteristic curves for compacted fine-grained soils." 1995. http://catalog.hathitrust.org/api/volumes/oclc/34106169.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1995.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 172-178).
36
Chen, Yi-Wen, and 陳怡雯. "Studying on soil water characteristic curve and irrigation water requirements for paddy and upland crops." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/92855731761826258989.
Full textAbstract:
碩士立德管理學院
資源環境研究所
92
Since the entry into WTO, Taiwan faces the urgency of water usage regulation for agricultural water management. The soil water characteristic curve of the soil suction and soil water content is determined for reference to estimate agriculture water requirements for upland and paddy crops. Watermark and datalogger are installed at depth of 5cm, 10cm, 20cm, 30cm, 40cm, 60cm, and 90cm underneath the ground surface in the HsuehChai Experiment Station of ChaiNan Irrigation Association to collect soil suction data. Soil water gravimetric method, sandbox test, and pressure cooker test are applied to measure the soil water content. The results are applied to obtain the soil water characteristic curve, and RETC model is applied to obtain the parameters for the soil water characteristic curve: (1) θr =0.067; (2) θs =0.341; (3) α=0.0579; (4) n=2.4098; (5) m=0.585; the relative coefficient is 0.95. In other words, the soil water characteristic curve and its parameters for seven soil layer depth are obtained. Field tests are conducted at HsuehChai Experiment Station, and the experiment fields include: (1) regular paddy field irrigation area; (2) adjusted irrigation project area for paddy crop, and (3) upland crop area. The field tests are conduced for double paddy field in early July. Based on soil water characteristic curve, the water budget balance method and irrigation management model can applied to simulate crops water requirements in future work.
37
"An Engineering Model of Hysteresis for Soil-Water Characteristic Curves." Thesis, 2001. http://hdl.handle.net/10388/7138.
Full textAbstract:
Soil-water characteristic curves play an important role in understanding the behaviour of unsaturated soils. Soil-water characteristic curves have been used to estimate the hydraulic conductivity and shear strength functions. The hysteretic nature of soil-water characteristic curves has been known for a long time but in most engineering and agriculture applications the soil-water characteristic curves have been assumed to be unique. It is not possible to measure all possible hysteretic soil-water characteristic curves for a soil. A simple model is required to predict hysteretic soil-water characteristic curves based on a few measured data points in order to apply the effect of hysteresis in the engineering practice.
A summary of the development of the various models that have been proposed in
the literature to predict soil-water hysteresis is presented in this thesis. Some
modifications to the existing soil-water hysteresis models are described. Seven soil water hysteresis models are selected and compared based on datasets collected from the research literature and obtained from a laboratory test program. In addition, an investigation of the hysteretic characteristics of the soil-water characteristic curve was implemented.
Six soil-water hysteresis models found in the research literature; namely, 1)
Mualem (1974) model-II, 2) Mualem and Miller (1979) model-IIIexp, 3) Mualem (1984) independent model, 4) Mualem (1984) dependent model, Hogarth et al. (1988) model and M. Feng and M. Fredlund (1999) model were selected for comparison. One more hysteresis model; namely, the Simplified version of the Feng and M. Fredlund (1999) model were added for comparison. The comparison of the soil-water hysteresis models was based on three criteria; namely, 1) Percentage deviation, 2) Absolute percentage deviation and 3) R squared. The results showed that the Man Feng and Fredlund (1999) model using two measured data points is the most appropriate model for predicting the main wetting curve. The Mualem (1974) model-II is the best model for predicting scanning curves. The R squared criterion is not a reliable criterion for comparing soil-water hysteresis models. The investigation of the hysteretic nature of the soil-water characteristic curve found that there are some consistent relationships between the initial drying curve, the main drying curve and the main wetting curve. These relationships provide a simple method to estimate the initial drying curve from the main wetting curve or the main drying curve. The study also indicated that some modifications to the measured data points are needed in order to obtain reasonable best-fit hysteretic soil-water characteristic curves.
In practice, it is hard to know the hysteretic history of the soil-water
characteristic curve (Le., wetting and drying cycles); therefore it is not applicable to
apply a soil-water hysteresis model requiring the hysteretic history of the soil-water
characteristic curve. A method of predicting scanning curves passing through any given point inside the main hysteresis loop does not require that the hysteretic history of the soil sample be known is presented in this thesis. This method is simple and applicable in engineering practice.
38
Hsieh, Ai-chih, and 謝艾芝. "Characteristic of Particulate Composition in Near-shore Water surrounding Taiwan." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/37868311107427096133.
Full textAbstract:
碩士國立中山大學
海洋科學系研究所
104
Suspended particulate matter in coastal water includes abiotic (mineral) and biotic particles,and terrestrial and marine particles which can be defined by its composition. Mineral particles are composed of mineral material derived from the weathering of crustal material, and are mainly consist of quratz and other primary aluminosilicate minerals. The biogenic component is generated in situ or externally by biological process, and includes microorganisms, plankton, fecal matter and marine and terrestrial plant debris. Mineral and biogenic particles can not be easily separated during sampling, so Al, which was regarding as a tracer of terrestrial lithogenic particles, is usedto calculate the percentages of mineral/biogenic contribution in suspended particles. In order to understand the contribution of marine or terrestrial sources, particulate organic carbon (POC), C/N ratio, chlorophyll aand phaeopigment a, were determined in size-fractionated coastal particles to characterized various sources of particles in coastal seawaters off Taiwan. Seasonal variation was accessed with samples collected on May and Octocber, 2012. In this study, I found that the concentrations of suspended particulate matter (SPM), chlorophyll a and phaeopigment a in wet season are hgher than in dry season. Besides, there is no significant seasonal variation in the concentrations of Al. A significant portion of suspended particles in coastal waters surrounding Taiwan are composed of marine particles, except for those stations near high discharge and suspended particulate matter in May 2012, which are composed of predominantly terrestrial particles.
39
Chang, Shu-Ting, and 張舒婷. "Study of Soil Water Characteristic curve and Unsaturated Hydraulic Conductivity." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/54871029053750955698.
Full textAbstract:
碩士中興大學
水土保持學系所
95
The experimental system of hydraulic conductivity in the laboratory were setup, and the water characteristic curves were measured by pressure plate. Water characteristic curves and unsaturated hydraulic conductivity of different soil texture (sandy loam, clayey loam, loam) were obtained. The parameters of van Genuchten Model were obtained by curve fitting technique and then to calculate hydraulic conductivity. In order to understand whether this experiment could substitute for the pressure plate, and discusses the usable parameter of these three soils. The result shows that our experiment can obtain the best water characteristic curve in the clayey loam, next is the sandy loam, latter is the loam. The result of the unsaturated conductivity experiment shows that the most correct experiment is in the clayey loam, next is the loam, latter is the sandy loam. The parameters of the van Genuchten Model are α=0.00194, n=2.455; α=0.00168, n=2.695; α=0.00137, n=3.151 for sandy loam, loam and clayey loam respectively in this study.
40
Chang, Li Chung, and 張力中. "Application of Characteristic Periodic Waveto Spectrum Deformation in Shallow Water." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/11687252009963866619.
Full text
41
Chen, Yung-Wen, and 陳湧文. "Use of Flow Pump Method forSoil-Water Characteristic Curve Measurement." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/tm2fd7.
Full textAbstract:
碩士國立臺灣大學
土木工程學研究所
105
In unsaturated soil mechanics, the soil-water characteristic curve (SWCC) represent the relationship between soil suction and soil water content. SWCC is an essential constitutive relationship for solving geotechnical engineering problems, such as slope stability, retaining walls and collapse of surface soil due to rainfall infiltration. Over the past few decades, many standard tests have been developed to evaluate and determine the SWCC. Among them, the ASTM pressure plate method has been widely used due to its convenience and reliability. However, it is difficult to determine if the specimen reaches the steady state because the only way to evaluate is observing its drainage condition. It causes the experimental duration too longer, approximately one to three months to obtain a SWCC. The flow pump method, proposed by Olsen in 1966, controls the flow rate of water entering or leaving the specimen. This method has been applied to measure SWCC in past few years. In particular, it is capable of obtaining continuous drying and wetting curves. In this study, the remolded kaolinite clay was selected to conduct the permeability test, where the performance of the flow pump is verified. Flow pump system, triaxial system, 3D printing technology, axis translation technique and modified suction drop method were put together to establish an SWCC measurement system. Fine quartz sand was used as test material for this research. Results showed that this experimental system is capable of determining the drying SWCC efficiently, costing less experimental time.
42
Wang, Ching-Wei, and 王勁崴. "Fabrication and Characteristic of Oil/Water Separation Membrane by Polyvinyl Alcohol." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/588zp2.
Full textAbstract:
碩士國立高雄應用科技大學
化學工程與材料工程系碩士在職專班
103
This study used stainless steel mesh to dip in the solution contained polyvinyl alcohol(thickener, PVA) and acrylamide(monomer, AM), followed by the baking or UV-light curing process to obtain compactly PAM oil-water separation membrane. The effects of membrane’s monomer conversion, mesh coverage and the efficiency and the rate of oil-water separation were discussed by the thickeners(PAM or PVA), the proportion of PVA and AM, the baking temperature and the polymerization procedure. Experimental data showed that the ability of oil-water separation was enhanced owing to better dispersion of PVA thickener. On the condition of adding proportion of 3 : 1, membrane had optimal concentration of AM and the better ability of oil-water separation; on the condition of adding proportion of 1 : 1, membrane had higher concentration of AM, oil or water cannot pass through the membrane; on the condition of adding proportion of 7 : 1, membrane had lower concentration of AM, the oil droplets will pass through the membrane. Higher baking temperature(80℃) will enhance the conversion of PAM and improve the ability of oil-water separation. Process on the UV illumination after baking(P1 process) makes the mesh bigger and the oil-water separation efficiency lower. Process on the baking after UV illumination(P2 process) makes the mesh smaller , oil-water separation efficiency higher and oil-water separation rate lower. At last, the effect of ability of oil-water separation on the surface tension, specific gravity and density of wasted oil-water were discussed on the oil types, temperature of wasted oil-water, concentration of sodium chloride, surfactant and sonication. The results showed that the more difference on the surface tension between oil and water, the lower oil-water separation efficiency; the higher wasted oil-water temperature will decrease the ability of oil-water separation. Increasing the concentration of sodium chloride resulted in the increasing the disparity of wasted oil-water specific gravity and the speed of wasted oil-water separation. Adding surfactant caused oil droplets emulsified and sonication process caused oil droplets physically broken to narrow particle size. Both decreased the ability of wasted oil-water separation.
43
Lu, Po-Hsien, and 盧柏憲. "A Study of Dynamic Characteristic for Water Drop on PVC Surface." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93293112428650818270.
Full textAbstract:
碩士國立臺灣科技大學
材料科學與工程系
101
In this work, the wetting phenomenon, drop morphology and bubble-entrapment behavior were studied for water drop impinging on PVC polymer surface. These phenomena during the drop impact are dependent upon the liquid properties (density, viscosity and surface tension), impact velocity, drop size, and solid properties (roughness and surface hydrophobicity). A high speed video camera was utilized for this study and both the images of the side view and 45 degree topic view were recorded continuously. Water drops of different sizes were used on the impact study onto the PVC planar surface. The relaxations of drop wetting diameter, drop high and contact angle were recorded for studying the wetting phenomenon from the side view images. The bubble entrapment behavior was investigated from the 45 degree topic view images. Three drop sizes (D0 =2.38, 3.14, and 3.87 mm) were used in this work. We observed the following phenomena from this study: (i) , (ii), (iii) and (iv). (i)A half closed region on the Vi-D0 plot was identified for the formation of entrapped bubble. The upper and lower boundaries of Vi showed a tendency of decreasing as D0 increases. The entrapped bubble generally resulted in a hemispherical bubble after settling down on PVC surface. (ii)The Re-We curve increase depend on the drop size increase. (iii) With the analyze of needle 28, diameter of maximum bubble inverse with speed of impact. And impact speed also inverse with drop height. (iv) The lowest height of drop with bubble is higher than the normal one. What’s more is drop size affect drop behave directly.
44
Hunz, ching-Hui, and 洪靖惠. "Relationship of Soil Water Characteristic Curve Parameters and Soil Physical Properties." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/04470970323123284989.
Full textAbstract:
碩士國立中興大學
水土保持學系所
96
This study used the pressure plate experiment to obtain soil water characteristic curves in the laboratory. Thirteen soil samples includeng sand, sandy loam, loam, clayey loam, and clay used to establish the relationship of soil water content and pressure potential. The parameters α and n of the van Genuchten Model were obtained by curve fitting technique. Multiple regression equations were estimated using soil physical properties and statistical SPSS software. Three soil samples were used to validate suitability of the equations. This study also defined the range of the equation parameters for different soil texture in Taiwan. Six soil physical properties including bulk density, porosity, field capacity, percent of sand, percent of clay, organic matter content were correlated with α and n parameters of the van Genuchten model. Regression analysis results showed that the equation parameter α and n related the best with the loamy soil water characteristic curve, followed by sandy loam, and clay loam. The estimated regression equation were as follows: ln(α)=1.228BD+8.226*10-2f-5.868*10-2FC+4.86*10-2sand+2.885*10-2clay+0.233C-12.743 ln(n)=2.239BD+4.49*10-2f-1.243*10-2FC+4.254*10-3sand+9.193*10-3clay+1.397*10-2C-4.838 The range of the van Genuchten Model for parameter α is as 0.002734 cm-1 for sand；0.001695∼0.014591cm-1 for sandy loam；0.000460∼0.002804cm-1 for loam；0.000292∼0.017212cm-1 for clay loam；0.000247∼0.000447cm-1 for clay. Due to the parameter n was not significantly related to soil texture, its range, therefore, was not defined in this study.
45
Lin, Chien-Chih, and 林建智. "Characteristic of Production of Hydrogen by Proton Exchange Membrane Water Electrolysis." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/94964403166692957491.
Full textAbstract:
碩士元智大學
機械工程學系
95
Pt is usually used as H2 electrode catalyst of proton exchange membrane water electrolysis (PEMWE), and Pt-IrO2 is for O2 electrode. Although the use of IrO2 may reduce the amount of Pt, IrO2 is not a commercial product so that its use will increase the cost of the system. Therefore, this study is intended to synthesize the Pt and Pt-Ru catalysts served as H2 and O2 electrode catalysts of PEMWE and evaluate the performance of production of hydrogen in order to reduce the cost. The impregnation method was employed to synthesize the catalysts. The modifications of catalysts were conducted by changing different environments and pH values, as well as heat treatments. After characterizing the properties of catalysts, three kinds of individual catalysts were chosen and applied to an electrode membrane assembly (MEA) to determine the performance of PEMWE. In addition, the commercial Pt-black and Pt-Ru catalysts were used for comparison. The purities of as-prepared Pt and Pt-Ru catalysts are almost higher than 90 %, with an average powder size of 5-20 nm. Increase in pH value can improve the purities of Pt and Ru; however, heat treatment seems to significantly reduce the purity of Ru. The results of X-ray diffraction (XRD) analysis indicate that there are f.c.c. Pt peaks located at 2θ are 39, 46, and 67 o, which can be indexed to Pt (1 1 1), Pt (2 0 0), and Pt (2 2 0), respectively. The reason that there is lack of Ru peak in XRD patterns could be the content of Ru in Pt-Ru powders is less than 52 wt. %. It can be seen from the data that specific surface area, total pore volume and average pore size of catalysts increase with increasing pH value. Heat treatments appear to deteriorate the material properties of catalysts, which could be attributed to the agglomeration of catalyst powders. The ratio of catalyst to Nafion solution of 3, and the loadings of Pt-black of 2 mg/cm2 and Pt-Ru of 4 mg/cm2 show the highest performance of PEMWE. Water is the optimal electrolyte but the temperature impact of electrolyte is different from the results in literature. Moreover, no matter Pt or Pt-Ru, the catalysts prepared in air without pH adjustment and heat treatment can produce the best performance of PEMWE.
46
Tsai, Meng-Fen, and 蔡孟棻. "Evaluating Stability of Unsaturated Soil Slope Using Soil-Water Characteristic Curve." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/24126059893850809346.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
93
Classical soil mechanics doesn’t consider the influence of the matric suction in unsaturated soils on shear strength. However, mechanics of unsaturated soils is involved in many geotechnical problems. The objective of this study is to estimate the shear strength of unsaturated soils by using a simplified method. Base on the pressure plate test, the salt solution test and the filter paper test on Linkou Terrace Lateritic Soil, the equation of complete soil-water characteristic curve is established from the regressive analysis. At last, the shear strength of unsaturated soil estimated from the soil-water characteristic curve is used in the numerical analysis. The results indicate that a reasonable complete soil-water characteristic curve can be established from the pressure plate test and the salt solution test. Key parameters determined from the soil-water characteristic curve are Air Entry Suction(ua-uw)a=290kPa, Residual Matric Sucion(ua-uw)r=21000kPa, Saturated Volumetric Water content θs =0.54, Residual Volumetric Water content θr=0.0216. It is more reasonable to analyze the slide behavior of the unsaturated soil slope by using the shear strength estimated from soil-water characteristic curve. Compared to using the shear strength obtained from the traditional triaxial unsaturated unconfining undrained (UUU) shear strength test, it is more rigorous to apply the model proposed by this study while analyzing the stability of the unsaturated soil slope.
47
Lin, Ming-Yi, and 林明毅. "A Study of Pedotransfer Function Application for Estimating Water Characteristic Curve." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/84070493343127583065.
Full textAbstract:
碩士中興大學
水土保持學系所
99
The soil water characteristic curves(SWCC) is one of the important soil hydraulic property, however the experiment is time-consuming. In recent years the scholars propose pedotransfer function one after another, predicting the soil water characteristic curve by using common property. To provide a convenient method for later study. This study analysis 22 samples which were collected around Taiwan. Predicting the basic soil properties and soil water characteristics curve, 12 samples were chosen randomly as training set and estimate the hydraulic parameters α and n by curve fitting technique of the van Genuchten Model. Laters using principle components analysis summarize the regression of α and n in training set. The accuracy of the equations were validated by other 10 soil samples. The regression equations were as follows: ln(α)=-0.06458×BD+0.001045×Sa-0.01297×C-0.11505×FC+0.106199×OM ln(n)=0.7138-0.26254×BD-0.0002×Sa+0.00058×C -0.00527×FC-0.0113×OM The results shows that the coefficient of determination (R2) of the parameter ln(α)、ln(n) of the estimating equations are 0.996 and 0.842. The root mean square error (RMSE) of parameter ln(α) 、ln(n) are 1.333 and 0.093 respectly, . In the estimation of water characteristic curve, the sampling location and the soil information were randomly chosen when validated the regression equation, the range of RMSE is 0.021~0.063. The applicability is better than previous study in different texture.
48
Tu, Shan-Tai, and 涂展台. "The measurement of Soil Water Characteristic Curves on Tea Plantation under Different Soil and Water Conservation Practices." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/19773406815934378817.
Full textAbstract:
碩士國立中興大學
水土保持學系
87
Abstract The purpose of this study is to determine the soil water characteristic curves under different treatment of the tea plantation. The model suggested by Haverkamp et al.(1977) and Van Genuchten(1980) were used. The parameters of these models were determined with the experimental data by curve fitting technology. The result indicated that the following equations were the best to describe the water characteristics curve of different soil conservation treatment. (Keywords:Soil and Water Conervation Treatment, Cover, Mulch, Water Characteristic Curve)
49
Hung, Hung-ming, and 洪銘鴻. "Stability Analysis of Unsaturated Colluvium Soil Slope Using Soil-Water Characteristic Curve." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/57318747494376449095.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
98
Former studies have indicated that unstable slope locating near the watershed of a reservoir is often covered by unsaturated colluvium soils. During the dry season, high matric suction exists in the ground and maintains its stability. However, after rainfall the collapse of soil slope can occur due to infiltration and saturation of the surface soils. In order to understand the colluvium soil characteristics including both macroscopic and microscopic properties, this study adopts the colluvium soil samples nearby the Sha Lun Tsai landslide area in Shihmen reservoir. The variation of soil characteristics is investigated by samples taken from different location. A series of experiments including both field and lab tests were conducted. The soil water characteristic curve (SWCC) was used to estimate the unsaturated shear strength parameters. The slope stability analyses were, then, performed using STEDwin 2.64 program at various rainfall infiltration levels. In addition, this study also preliminary develops a set of stress-dependent SWCC equipment for future study to evaluate the effect of stress state on the SWCC. The test results exhibit that the colluvium soil samples of the same watershed mainly contain illite mineral with similar percentage of content. Moreover, the water retention capacity of the remold colluvium soil and undisturbed residual soil is better than that of the undisturbed colluvium soil. Slope stability analyses indicated that the factor of safety decreases with the increase in rainfall infiltration depth, and the potential slip surface becomes shallower when the infiltration depth increases. Therefore, it can be concluded that the “wetting-front” of rainfall infiltration is the most essential factor that can induce shallow slip failure of the colluvium soil slope.
50
Kao, Shih Chieh, and 高士傑. "Conceptual Design of Applying the Characteristic of Crawler Water Turbine to Channels." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/71468669074725406235.
Full textAbstract:
碩士國立聯合大學
機械工程學系碩士班
102
In recent years, most of existing energy resources have been nearly drained out, so that some small energy resources that ignored by the governments may become good complementary energy resources. This study investigates the performance and the design of a biaxial crawler turbine. The flow field and press, distribution of turbine blades were simulated by a 3-D finite element model. Moreover, the result of analysis shows that the efficiency of generating electric power is different by changing the pitch of blades. Under the influence of swirls, the proposed turbine will have the starting torque above two motors when the blade pitch is more than 270mm. The efficiency of the proposed turbine will be changed by changing its speed and motor of different starting torque. To coordinate with environment and improve more efficiency, it is also available to change the design of module.