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Influences affecting the soil-water characteristic curve 被引量:9
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作者 周建 俞建霖 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2005年第8期797-804,共8页
The soil-water characteristic curve (SWCC) is the primary partially saturated soil information as its behavior and properties can be derived from it. Although there have been many studies of unsaturated soils and the ... The soil-water characteristic curve (SWCC) is the primary partially saturated soil information as its behavior and properties can be derived from it. Although there have been many studies of unsaturated soils and the SWCC, there is still no combined constitutive model that can simulate soil characteristics accurately. In cases when hydraulic hysteresis is dominant (e.g. under cyclic loading) it is particularly important to use the SWCC. In the past decades, several mathematical expressions have been proposed to model the curve. There are various influences on the SWCC as a source of information, so the curves obtained from conventional tests often cannot be directly applied; and the mathematical expressions from one scenario cannot be used to simulate another situation. The effects of void ratio, initial water content, stress state and high suction were studied in this work revealing that water content and stress state are more important than the other effects; but that the influences tend to decrease when suction increases. The van Genuchten model was modified to simulate better the changes in the degree of saturation at low values of suction. Predictions were compared with experimental results to determine the simulation capability of the model. 展开更多
关键词 soil-water characteristic curve (SWCC) Unsaturated soil Mathematical expression
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Predicting the entire soil-water characteristic curve using measurements within low suction range 被引量:5
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作者 YE Yun-xue ZOU Wei-lie +1 位作者 HAN Zhong LIU Xiao-wen 《Journal of Mountain Science》 SCIE CSCD 2019年第5期1198-1214,共17页
The soil-water characteristic curve(SWCC) is widely used in the design and evaluation in the practice of geotechnical and geoenvironmental engineering such as the slope stability under the influence of environmental f... The soil-water characteristic curve(SWCC) is widely used in the design and evaluation in the practice of geotechnical and geoenvironmental engineering such as the slope stability under the influence of environmental factors. The SWCC has distinct features in the capillary and adsorption zones due to different physical mechanisms. Measurements of the SWCC are typically limited within the capillary zone(i.e., low suction range). It is cumbersome and time-consuming to measure the SWCC in the adsorption zone(i.e., high suction range). This study presents a simple method to predict the entire SWCC within both the capillary and adsorption zones, using measured data only from low suction range(e.g., from 0 to 500 kPa). Experimental studies were performed on a completely weathered granite residual soil to determine its entire SWCC from saturated to dry conditions. The resultant SWCC, along with the SWCC measurements of 14 soils reported in the literature, were used to validate the proposed method. The results indicate that the proposed method has good consistency with a wide array of measured data used in this study. The proposed method is easy to use as it only requires a simple parameter calibration for a commonly used SWCC model. It can be used to improve the reliability in the prediction of the SWCC over the entire suction range when measurements are limited within the low suction range. 展开更多
关键词 UNSATURATED SOILS soil-water characteristic curve CAPILLARY Adsorption Prediction
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Prediction of loess soil-water characteristic curve by mercury intrusion porosimetry 被引量:4
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作者 LI Hua LI Tong-lu +1 位作者 LI Ping ZHANG Ya-guo 《Journal of Mountain Science》 SCIE CSCD 2020年第9期2203-2213,共11页
Mercury intrusion porosimetry(MIP)is a simple and fast way to obtain the pore distribution of soil and can be used to estimate the soil-water characteristic curve(SWCC).In previous studies,soil was assumed to be a per... Mercury intrusion porosimetry(MIP)is a simple and fast way to obtain the pore distribution of soil and can be used to estimate the soil-water characteristic curve(SWCC).In previous studies,soil was assumed to be a perfect wettability material,and the contact angle(CA)of the soil-water interface was taken as zero in the SWCC prediction method.However,the CA has proved to be much greater than zero even for hydrophilic soils according to some soil wettability experiments,and it has a significant effect on predicting the SWCC.In this research,a method for predicting the SWCC by MIP,which takes the CA as a fitting coefficient,is proposed.The pore size distribution curves are measured by MIP,and the SWCCs of two loess soils are measured by pressure plate and filter paper tests.When the CA is taken as70°and 50°for the wetting and drying process,respectively,the SWCCs predicted by the pore size distribution curves agree well with the measured SWCCs.The predicted suction range of the proposed method is 0-105 k Pa.The consistency of the results suggests that utilizing the MIP test to predict the SWCC with a proper CA is effective for loess. 展开更多
关键词 soil-water characteristic curve Mercury intrusion porosimetry Contact angle LOESS
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Effects of sample dimensions and shapes on measuring soil-water characteristic curves using pressure plate 被引量:8
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作者 Min Wang Lingwei Kong Meng Zang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2015年第4期463-468,共6页
It is well known that soilewater characteristic curve (SWCC) plays an important role in unsaturated soil mechanics, but the measurement of SWCC is inconvenient. In laboratory it requires days of testing time. For fi... It is well known that soilewater characteristic curve (SWCC) plays an important role in unsaturated soil mechanics, but the measurement of SWCC is inconvenient. In laboratory it requires days of testing time. For fine-grained clays, it may last for a couple of months using pressure plate tests. In this study, the effects of sample dimensions and shapes on the balance time of measuring SWCCs using pressure plate tests and the shape of SWCCs are investigated. It can be found that the sample dimensions and shapes have apparent influence on the balance time. The testing durations for circular samples with smaller diameters and annular samples with larger contact area are significantly shortened. However, there is little effect of sample dimensions and shapes on the shape of SWCCs. Its mechanism is explored and discussed in details through analysing the principle of pressure plate tests and microstructure of the sample. Based on the above findings, it is found that the circular samples with smaller dimensions can accelerate the testing duration of SWCC using the pressure plate. 展开更多
关键词 soil-water characteristic curve (SWCC)Pressure plateMercury intrusionMicrostructureExpansive soil
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Water infiltration and soil-water characteristics of compacted loess under applied vertical stress
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作者 ZHANG Lin LI Tong-lu +2 位作者 LI Ji-heng LIANG Wei CHEN Cun-li 《Journal of Mountain Science》 SCIE CSCD 2023年第3期873-885,共13页
Additional stress formed by postconstruction buildings in loess-filling areas affects water infiltration in soil and causes soil deformation.To investigate this effect,under constant water head,vertical infiltration t... Additional stress formed by postconstruction buildings in loess-filling areas affects water infiltration in soil and causes soil deformation.To investigate this effect,under constant water head,vertical infiltration tests on compacted loess with two initial dry densities for different applied vertical stresses were developed using vertical stresscontrollable one-dimensional soil columns.The timehistory curves of vertical deformation,wetting front depth,cumulative infiltration depth,volumetric water content(VWC)and suction were measured,and the soil-water characteristic curves(SWCCs)were determined.The results showed that:(1)the infiltration ability of the soil column weakens with increasing applied vertical stress and initial dry density;(2)vertical deformation increases rapidly at first and then tends to be stable slowly at the consolidation and wetting-induced deformation stage,and is positively correlated with applied vertical stress and is negatively correlated with initial dry density.The stability time of wetting-induced deformation and the corresponding wetting front depth increase with the increase of applied vertical stress,while they decrease obviously when initial dry density increases;(3)the influence of applied vertical stress on soilwater characteristics in soil columns with various initial dry densities is related to the deformation depth of soil column.The VG(Van Genuchten)model is suitable for fitting the SWCCs at different monitoring positions.A normalized SWCC model introducing the applied vertical stress was proposed for each initial dry density using the mathematical relationship between the fitting parameters and the applied vertical stress. 展开更多
关键词 Additional stress LOESS Vertical deformation Wetting front Soil column soil-water characteristic curves
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Soil freezing process and different expressions for the soil-freezing characteristic curve 被引量:5
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作者 Jun Ping Ren Sai K.Vanapalli Zhong Han 《Research in Cold and Arid Regions》 CSCD 2017年第3期221-228,共8页
The soil-freezing characteristic curve(SFCC),which represents the relationship between unfrozen water content and subfreezing temperature(or suction at ice-water interface)in a freezing soil,can be used for understand... The soil-freezing characteristic curve(SFCC),which represents the relationship between unfrozen water content and subfreezing temperature(or suction at ice-water interface)in a freezing soil,can be used for understanding the transportation of heat,water,and solute in frozen soils.In this paper,the soil freezing process and the similarity between the SFCC of saturated frozen soil and soil-water characteristic curve(SWCC)of unfrozen unsaturated soil are reviewed.Based on similar characteristics between SWCC and SFCC,a conceptual SFCC is drawn for illustrating the main features of soil freezing and thawing processes.Various SFCC expressions from the literature are summarized.Four widely used expressions(i.e.,power relationship,exponential relationship,van Genuchten 1980 equation and Fredlund and Xing 1994 equation)are evaluated using published experimental data on four different soils(i.e.,sandy loam,silt,clay,and saline silt).Results show that the exponential relationship and van Genuchten(1980)equation are more suitable for sandy soils.The simple power relationship can be used to reasonably best-fit the SFCC for soils with different particle sizes;however,it exhibits limitations when fitting the saline silt data.The Fredlund and Xing(1994)equation is suitable for fitting the SFCCs for all soils studied in this paper. 展开更多
关键词 FROZEN soil soil-freezing characterISTIC curve Clapeyron equation soil-water characterISTIC curve UNFROZEN water content
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Soil-water characteristics and shear strength in constant water content triaxial tests on Yunnan red clay 被引量:6
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作者 马少坤 黄茂松 +1 位作者 扈萍 杨超 《Journal of Central South University》 SCIE EI CAS 2013年第5期1412-1419,共8页
The shear strength parameters for geotechnical designs are obtained mainly from consolidated drained (CD) or consolidated undrained (CU) triaxial tests. However, during construction, the excess pore-air pressure g... The shear strength parameters for geotechnical designs are obtained mainly from consolidated drained (CD) or consolidated undrained (CU) triaxial tests. However, during construction, the excess pore-air pressure generally dissipates instantaneously while the excess pore-water pressure dissipates with time. This condition needs to be simulated in a constant water content (CW) triaxial test. The study on Yunnan red clay is carried out to investigate the soil-water characteristics and the shear strength characteristics under the constant water content condition. Osmotic technique is used to obtain the soil-water characteristic curve. A series of CW triaxial tests are conducted on statically compacted specimens. The experimental results show that the soil-water characteristic curve has a low air entry value of 7 kPa due to large pores in non-uniform pore size distribution, and a high residual value exceeding 10 MPa. In addition, the initial degree of saturation and net confining stress play an important role in affecting the shear characteristics under the constant water content condition. Finally, a new semi-empirical shear strength model in terms of degree of saturation is proposed and then applied to Yuunan red clay. Simulation result shows that the model is capable of capturing some key features of soils. The model can be used in whole engineering practice range, covering both unsaturmed and saturated soils. 展开更多
关键词 Yunnan red clay soil-water characteristic curve shear strength constant water triaxial test
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Determining the soil-water retention curve using mercury intrusion porosimetry test in consideration of soil volume change 被引量:6
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作者 Wen-Jing Sun Yu-Jun Cui 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2020年第5期1070-1079,共10页
It is well-known that a close link exists between soil-water retention curve(SWRC)and pore size distribution(PSD).Theoretically,mercury intrusion porosimetry(MIP)test simulates a soil drying path and the test results ... It is well-known that a close link exists between soil-water retention curve(SWRC)and pore size distribution(PSD).Theoretically,mercury intrusion porosimetry(MIP)test simulates a soil drying path and the test results can be used to deduce the SWRC(termed SWRCMIP).However,SWRCMIP does not include the effect of volume change,compared with the conventional SWRC that is directly determined by suction measurement or suction control techniques.For deformable soils,there is a significant difference between conventional SWRC and SWRCMIP.In this study,drying test was carried out on a reconstituted silty soil,and the volume change,suction,and PSD were measured on samples with different water contents.The change in the deduced SWRCMIP and its relationship with the conventional SWRC were analyzed.The results showed that the volume change of soil is the main reason accounting for the difference between conventional SWRC and SWRCMIP.Based on the test results,a transformation model was then proposed for conventional SWRC and SWRCMIP,for which the soil state with no volume change is taken as a reference.Comparison between the experimental and predicted SWRCs showed that the proposed model can well consider the influence of soil volume change on its water retention property. 展开更多
关键词 soil-water retention curve(SWRC) Mercury intrusion porosimetry(MIP) Pore size distribution(PSD) Deformable soils
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Soil-water characteristics of Gaomiaozi bentonite by vapour equilibrium technique 被引量:2
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作者 Wenjing Sun De'an Sun +1 位作者 Lei Fang Shiqing Liu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2014年第1期48-54,共7页
Soil-water characteristics of Gaomiaozi(GMZ)Ca-bentonite at high suctions(3–287MPa)are measured by vapour equilibrium technique.The soil-water retention curve(SWRC)of samples with the same initial compaction states i... Soil-water characteristics of Gaomiaozi(GMZ)Ca-bentonite at high suctions(3–287MPa)are measured by vapour equilibrium technique.The soil-water retention curve(SWRC)of samples with the same initial compaction states is obtained in drying and wetting process.At high suctions,the hysteresis behaviour is not obvious in relationship between water content and suction,while the opposite holds between degree of saturation and suction.The suction variation can change its water retention behaviour and void ratio.Moreover,changes of void ratio can bring about changes in degree of saturation.Therefore,the total change in degree of saturation includes changes caused by suction and that by void ratio.In the space of degree of saturation and suction,the SWRC at constant void ratio shifts to the direction of higher suctions with decreasing void ratio.However,the relationship between water content and suction is less affected by changes of void ratio.The degree of saturation decreases approximately linearly with increasing void ratio at a constant suction.Moreover,the slope of the line decreases with increasing suction and they show an approximately linear relationship in semi-logarithmical scale.From this linear relationship,the variation of degree of saturation caused by the change in void ratio can be obtained.Correspondingly,SWRC at a constant void ratio can be determined from SWRC at different void ratios. 展开更多
关键词 Gaomiaozi(GMZ) Ca-bentonite Vapour equilibrium technique soil-water retention curve(SWRC) Void ratio Degree of saturation Hydro-mechanical coupled parameter SWRC at constant void ratio
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Influence of Dry Density on Soil-Water Retention Curve of Unsaturated Soils and Its Mechanism Based on Mercury Intrusion Porosimetry
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作者 李博 陈宇龙 《Transactions of Tianjin University》 EI CAS 2016年第3期268-272,共5页
The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained ... The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained in the laboratory by using self-modified SWRC apparatus. In addition, the porosity and the pore size distribution of the samples were investigated by a mercury porosimetry test in order to analyze the effect of dry density. Results showed that the soil-water retention of the soil specimens was strongly dependent on the dry density. Under zero suction, soil specimens with a higher dry density exhibited lower initial volumetric water content. The higher the dry density of soil, the more slowly the volumetric water content decreased with the increase of suction. There was a general and consistent trend for a soil specimen to possess a larger air-entry value and residual suction, while smaller slope of SWRC when it had a higher density. This was probably attributed to the presence of smaller interconnected pores in the soil specimen with a higher dry density. The proportion of large diameter pores decreased in comparison to pores with small diameters in the soil tested. The measured total pore volume of the soil specimen, which had a larger dry density, was lower than that of the relatively loose specimens. 展开更多
关键词 soil-water retention curve dry density mercury intrusion porosimetry unsaturated soil
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Factors Influencing the Soil-Water Characteristics of Unsaturated Tropical Silty Sand
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作者 B. D. Oluyemi-Ayibiowu T. O. Akinleye 《Journal of Geoscience and Environment Protection》 2019年第5期264-273,共10页
Fine grain soils have a complex engineering behaviour which depends but not limited to moisture content, changes in external pressure and characteristics of the pore medium. Sand often contains a considerable percent ... Fine grain soils have a complex engineering behaviour which depends but not limited to moisture content, changes in external pressure and characteristics of the pore medium. Sand often contains a considerable percent of silt which is expected to alter its natural behaviour. This composite matrix is referred to as silty-sand. To understand the behaviour of this matrix under varying moisture conditions, some of the factors influencing the soil-water characteristics of unsaturated silty sands were investigated. Representative samples were collected from a river bank after its index properties were predetermined in the laboratory. The samples were compacted at different moisture conditions and compactive efforts. With the pressure plate extractor device, the Soil-Water Characteristic (SWC) was obtained and SWC Curves plotted. Compaction at greater compactive effort (modified proctor) and optimum moisture content produced the largest air entry value and reduced air voids. The air entry values of the soils obtained ranged from 21 kPa to 57 kPa. Also changes in the shape of the SWCC were consistent with changes in pore size which occur by varying compaction conditions. Result shows that soil structure, compaction water content, compactive effort and percentage of fine particles are factors affecting the Soil-Water Characteristics. 展开更多
关键词 soil-water characterISTICS soil-water characterISTICS curve TROPICAL Silty Sand Soil COMPACTION Water Content Compactive EFFORTS
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Cryptography with Elliptic Curve Using Tifinagh Characters
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作者 Fatima Amounas El Hassan El Kinani 《Journal of Mathematics and System Science》 2012年第2期139-144,共6页
The paper describes the concept of plaintext encryption by using the Unicode characters. In the case of elliptic curve cryptography, there is not specified rule or algorithm to specify the letters of Tifinagh as well ... The paper describes the concept of plaintext encryption by using the Unicode characters. In the case of elliptic curve cryptography, there is not specified rule or algorithm to specify the letters of Tifinagh as well as special characters. So, the paper gives the transformation of characters Tifinagh into points on elliptic curve by using the corresponding characters Latin. The obtained correspondence has been applied in Menezes-Vanstone cryptosystem based on elliptic curve. Therefore, the paper explains in detail its implementation in Maple 12. 展开更多
关键词 CRYPTOGRAPHY elliptic curve elliptic curve cryptography UNICODE Tifinagh characters ENCRYPTION DECRYPTION implementation.
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Soil−water characteristics of weathered crust elution-deposited rare earth ores 被引量:3
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作者 Zhong-qun GUO Jian-rong ZHOU +3 位作者 Ke-fan ZHOU Jie-fang JIN Xiao-jun WANG Kui ZHAO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第5期1452-1464,共13页
The permeability of the weathered crust elution-deposited rare earth ores directly affects the efficiency of in-situ leaching.The soil−water characteristic curve(SWCC)is an important constitutive relation for calculat... The permeability of the weathered crust elution-deposited rare earth ores directly affects the efficiency of in-situ leaching.The soil−water characteristic curve(SWCC)is an important constitutive relation for calculating the permeability of ore body,which is related to many factors.Soil−water characteristic tests of rare earth ore samples considering different factors were carried out by using the pressure plate instrument.Effects of dry density,particle size and solution leaching on water holding behavior and the mechanism were investigated.The experimental observations indicate that with the decrease of dry density,the pore ratio increases gradually,and the saturated water content increases.Under the same matric suction,the water content decreases gradually with the increase of particle size,thus decreasing water holding capacity of ore accordingly.In the same water content,matric suction is inversely proportional to particle size.Under the same matric suction,the water content of ore samples after leaching is less than that of the ore samples before leaching,indicating that solution leaching can decrease water holding capacity of ore. 展开更多
关键词 weathered crust elution-deposited rare earth ore dry density particle size solution leaching soil-water characteristic curve
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Effect of the uncertainty in soil-water characteristic curve on the estimated shear strength of unsaturated soil 被引量:2
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作者 Qian ZHAI Harianto RAHARDJO +2 位作者 Alfrendo SATYANAGA Guo-liang DAI Yan-jun DU 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2020年第4期317-330,共14页
Most failures or instabilities of geotechnical structures commonly result from shear failure in soil. In addition, many infrastructures are constructed within the unsaturated zone. Therefore, the determination of shea... Most failures or instabilities of geotechnical structures commonly result from shear failure in soil. In addition, many infrastructures are constructed within the unsaturated zone. Therefore, the determination of shear strength of unsaturated soil is crucial in geotechnical design. The soil-water characteristic curve(SWCC) is commonly used to estimate the shear strength of unsaturated soil because the direct measurement is time-consuming and costly. However, the uncertainty associated with the determined SWCC is rarely considered in the estimation of the shear strength. In this paper, the uncertainties of SWCC resulted from different factors are reviewed and discussed. The variability of the estimated shear strength for the unsaturated soil due to the uncertainty of SWCC associated with the best fit process is quantified by using the upper and lower bounds of the determined SWCC. On the other hand, the uncertainties of the estimated shear strength due to different initial void ratios or different confining pressures are quantified by adopting different SWCCs. As a result, it is recommended that the measured SWCC from the conventional Tempe cell or pressure plate needs to be corrected by considering different stress levels in the estimation of the shear strength of unsaturated soil. 展开更多
关键词 Unsaturated shear strength Pore-size distribution function VARIABILITY soil-water characteristic curve (SWCC) Confidence limits
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Effect of initial gravimetric water content and cyclic wetting-drying on soil-water characteristic curves of disintegrated carbonaceous mudstone 被引量:2
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作者 Ling Zeng Fan Li +2 位作者 Jie Liu Qianfeng Gao Hanbing Bian 《Transportation Safety and Environment》 EI 2019年第3期230-240,共11页
The soil-water characteristic curve(SWCC)is often used to estimate unsaturated soil properties(e.g.strength,permeability,volume change,solute and thermal diffusivity).The SWCC of soil samples is significantly affected... The soil-water characteristic curve(SWCC)is often used to estimate unsaturated soil properties(e.g.strength,permeability,volume change,solute and thermal diffusivity).The SWCC of soil samples is significantly affected by cyclic wetting-drying.To examine how water content and cyclic wetting-drying affect the SWCC of disintegrated carbonaceous mudstone(DCM),SWCC tests were implemented using a pressure-plate apparatus.In addition,SWCC models for DCM considering the initial gravimetric water content and cyclic wetting-drying were developed.The test results showed that the volumetric water content(θ)of the DCM first decreased rapidly and then became stable as matric suction(s)increased.The initial water content affected the SWCC by altering the pore structure of the DCM.For a given number of wetting-drying cycles,the higher the initial water content,the higher the stabilizedθ.At a given s value,θdecreased as the number of wetting-drying cycles increased,which suggests that cyclic wetting-drying reduces the water-holding capacity of DCM.The Gardner model for DCM was constructed considering initial water content and cyclic wetting-drying,and was effective at describing and predicting the SWCC model for DCM. 展开更多
关键词 embankment engineering disintegrated carbonaceous mudstone soil-water characteristic curve initial gravimetric water content cyclic wetting-drying
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Constructing quasi-random subsets of Z_N by using elliptic curves
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作者 LIN Zhi-xing CHEN Zhi-xiong 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2012年第1期105-113,共9页
Let ε : y^2 = x3 + Ax + B be an elliptic curve defined over the finite field Zp(p 〉 3) and G be a rational point of prime order N on ε. Define a subset of ZN, the residue class ring modulo N, asS:={n:n∈ZN,n... Let ε : y^2 = x3 + Ax + B be an elliptic curve defined over the finite field Zp(p 〉 3) and G be a rational point of prime order N on ε. Define a subset of ZN, the residue class ring modulo N, asS:={n:n∈ZN,n≠0,(X(nG)/p)=1} where X(nG) denotes the x-axis of the rational points nC and (*/P) is the Legendre symbol. Some explicit results on quasi-randomness of S are investigated. The construction depends on the intrinsic group structures of elliptic curves and character sums along elliptic curves play an important role in the proofs. 展开更多
关键词 elliptic curve quasi-random subset quasi-randomness character sum Legendre symbol.
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Soil-Water Charateristics of Tropical Clay Soil under High and Low Suction Conditions
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作者 Bamitale Dorcas Oluyemi-Ayibiowu Taiwo Olawale Akinleye +1 位作者 Olaolu George Fadugba Ayodeji Stanley Olowoselu 《Journal of Geoscience and Environment Protection》 2020年第11期162-175,共14页
Tropical clay soil was compacted at different moisture conditions (dry, wet and optimum) and compactive efforts (Reduced proctor, Standard proctor, West African standard and Modified proctor). Experimental Soil-Water ... Tropical clay soil was compacted at different moisture conditions (dry, wet and optimum) and compactive efforts (Reduced proctor, Standard proctor, West African standard and Modified proctor). Experimental Soil-Water Characteristics (SWC) of the soil was derived using the pressure plate extractor equipment and SWC Curves (SWCC) plotted as gravimetric water content versus logarithm of matric suction. The Air Entry Values (A.E.V) obtained from experimental work ranged from 21 kPa to 59 kPa and compared favourably well with those estimated from predictive models with values of 23 kPa to 52 kPa. Specimens compacted with greater compactive effort (Modified proctor) and at optimum moisture content produced the largest air entry value of 59 kPa and reduced air voids. Changes observed in the shape of the SWCC were consistent with changes in pore size which occurred by varying compaction conditions. The shape of the soil-water characteristics curve was found to depend on the soil structure, compactive water content and compactive effort and not solely on the percentage of fine particles. 展开更多
关键词 soil-water characteristics Tropical Clay Soil Compaction Water Content Compactive Efforts soil-water characteristics curve
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Devanagari Handwriting Grading System Based on Curvature Features
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作者 Munish Kumar Simpel Rani Jindal 《Computer Modeling in Engineering & Sciences》 SCIE EI 2017年第2期195-202,共8页
Grading of writers in perspective of their handwriting is a challenging task owing to various writing styles of different individuals.This paper presents a framework for grading of Devanagari writers in perspective of... Grading of writers in perspective of their handwriting is a challenging task owing to various writing styles of different individuals.This paper presents a framework for grading of Devanagari writers in perspective of their handwriting.This framework of grading can be useful in conducting the handwriting competitions and then deciding the winners on the basis of an automated process.Selecting the set of features is a challenging task for implementing a handwriting grading system of particular language.In this paper,curvature features,namely,parabola curve fitting and power curve fitting have been considered for extracting the vital information of writers,which can be helpful in grading the writers.For obtaining the classification score,k-NN classifier has been considered in the present work.Four printed Devanagari font styles,namely,Devlys,Krishna,Krutidev,and Utsaah have been considered for train the proposed model of handwriting evaluation.For evaluating the effectiveness of the proposed framework,we have conducted a mock test of 75 Devanagari writers(Left handed and Right handed)and noticed that the proposed framework performing well suitable for conducting the handwriting competition of Devanagari text writers.This work is also newly in the ground of Devanagari text recognition. 展开更多
关键词 Handwritten character recognition curvATURE features PARABOLA curve FITTING power curve FITTING K-NN
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基于图像边缘检测的扭曲文档矫正 被引量:2
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作者 徐远东 熊永平 +3 位作者 张铮 伍贵宾 张兴 王伟 《南京大学学报(自然科学版)》 CAS CSCD 北大核心 2023年第4期660-668,共9页
扭曲的文档图像会干扰文档图像的光学字符识别(Optical Character Recognition,OCR).为了对扭曲形变的文档图像进行矫正,提高扭曲文档识别的正确率,基于目标检测与分割的网络,提出文档图像的边缘检测方法,使用贝塞尔(Bezier)曲线拟合文... 扭曲的文档图像会干扰文档图像的光学字符识别(Optical Character Recognition,OCR).为了对扭曲形变的文档图像进行矫正,提高扭曲文档识别的正确率,基于目标检测与分割的网络,提出文档图像的边缘检测方法,使用贝塞尔(Bezier)曲线拟合文档图像的边缘曲线,通过目标检测的算法回归Bezier曲线的控制点.将文档图像的边缘检测转化为边缘曲线Bezier控制点的回归,使用文档的边缘点计算扭曲文档矫正后的矩形模板,然后将文档图像通过薄板样条插值(Thin Plate Spline,TPS)算法重映射到矩形模板中,完成文档的矫正.实验结果表明,提出的矫正方法能够对扭曲文档进行精确的边缘提取,和其他算法相比,经该算法矫正后的文档图像,其OCR的正确率有较大的提升. 展开更多
关键词 目标检测 贝塞尔曲线 文档图像矫正 光学字符识别 薄板样条插值
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基于车载图像的里程桩牌检测及桩牌号识别
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作者 彭帝 雷雪芹 《河南科技》 2023年第24期22-30,共9页
【目的】为解决当前道路定位误差大、里程桩定位困难等问题,对道路里程实现高效定位。【方法】采用CLAHE来增强路牌与背景对比度,用MSER和HOG来提取里程桩牌,并用SVM对百米桩和公里桩进行分类。用改进的CRAFT算法来识别公里桩,用Hough... 【目的】为解决当前道路定位误差大、里程桩定位困难等问题,对道路里程实现高效定位。【方法】采用CLAHE来增强路牌与背景对比度,用MSER和HOG来提取里程桩牌,并用SVM对百米桩和公里桩进行分类。用改进的CRAFT算法来识别公里桩,用Hough圆检测来定位百米桩,再用字符聚类网络来识别牌号。对识别失败而未录入的百米桩牌号的GPS信息,可用贝塞尔曲线和等距离插值法进行补缺。【结果】通过现场测试,里程桩分类的准确度达到93.29%,定位精度为0.938 m。【结论】该方法符合交通行业里程桩测量定位标准,且定位速度快、定位精度高。 展开更多
关键词 道路养护 自动化技术 路牌检测 字符识别 贝塞尔曲线
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