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
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
In this study, the differences in reservoir parameters, such as pore radius, throat radius, and pore-throat ratio, between the east and west subsags of the Lishui Sag are analyzed by using data obtained from a constan...In this study, the differences in reservoir parameters, such as pore radius, throat radius, and pore-throat ratio, between the east and west subsags of the Lishui Sag are analyzed by using data obtained from a constant-rate mercury injection experiment. Furthermore, the quality of the reservoirs in the two subsags is systematically evaluated. Results show that the throat radius of the Lishui west subsag is larger than that of the east subsag, and this parameter has a positive correlation with reservoir quality. However, the pore-throat ratio of the east subsag is larger than that of the west subsag, which has an inverse relationship with reservoir quality. The main reasons for this reservoir difference can be attributed to sedimentation and diagenesis. The sedimentary facies types of the Lishui east subsag are the fan delta, shore lake, shallow lake, and shore shallow lake;their sandstone composition maturity is low;the clay mineral content is high;and the rock has undergone strong diagenesis. Therefore, the physical conditions of the reservoir are poor. However, the sandstones in the Lishui west subsag have weak cementation and compaction, mainly with an intergranular pore structure type, which leads to good connectivity between pores. Therefore, the storage performance and seepage capacity of the Lishui west subsag are better than those of the east subsag;the west subsag is the main area of oil and gas accumulation, as confirmed in the process of exploration and development.展开更多
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
Since the end of the 1990s,cryptosystems implemented on smart cards have had to deal with two main categories of attacks:side-channel attacks and fault injection attacks.Countermeasures have been developed and validat...Since the end of the 1990s,cryptosystems implemented on smart cards have had to deal with two main categories of attacks:side-channel attacks and fault injection attacks.Countermeasures have been developed and validated against these two types of attacks,taking into account a well-defined attacker model.This work focuses on small vulnerabilities and countermeasures related to the Elliptic Curve Digital Signature Algorithm(ECDSA)algorithm.The work done in this paper focuses on protecting the ECDSA algorithm against fault-injection attacks.More precisely,we are interested in the countermeasures of scalar multiplication in the body of the elliptic curves to protect against attacks concerning only a few bits of secret may be sufficient to recover the private key.ECDSA can be implemented in different ways,in software or via dedicated hardware or a mix of both.Many different architectures are therefore possible to implement an ECDSA-based system.For this reason,this work focuses mainly on the hardware implementation of the digital signature ECDSA.In addition,the proposed ECDSA architecture with and without fault detection for the scalar multiplication have been implemented on Xilinxfield programmable gate arrays(FPGA)platform(Virtex-5).Our implementation results have been compared and discussed.Our area,frequency,area overhead and frequency degradation have been compared and it is shown that the proposed architecture of ECDSA with fault detection for the scalar multiplication allows a trade-off between the hardware overhead and the security of the ECDSA.展开更多
The electric energy injection from a pulsed power supply to a planar type of dielectric barrier discharge(DBD) reactor at atmospheric pressure was studied. Relations of the energy injection with barrier materials, bar...The electric energy injection from a pulsed power supply to a planar type of dielectric barrier discharge(DBD) reactor at atmospheric pressure was studied. Relations of the energy injection with barrier materials, barrier thickness, peak voltage, gap distance, electrode area,and operation temperature were experimentally investigated. The energy injection is a function of relative permittivity, barrier thickness, peak voltage, gap distance, and electrode area. The influence of operation temperature on energy injection is slight in the range of 27–300℃ but becomes obvious in the range of 300–500℃. A model was established using which the energy injection can be easily predicted.展开更多
Based on scanning electron microscopy and mercury porosimmetry,a large number of experimental data of pores and pore throats of tight sandstone reservoirs are obtained,and the characteristics of pore types,capillary p...Based on scanning electron microscopy and mercury porosimmetry,a large number of experimental data of pores and pore throats of tight sandstone reservoirs are obtained,and the characteristics of pore types,capillary pressure curves and quantitative parameters of pore throats of Yanchang Formation in Huangling mining area are studied.The results show that the main reservoir space types of Yanchang Formation sandstone are primary intergranular pores and feldspar dissolution pores.The pore-throat structure is medium-small pore and thin-small throat type,and the sorting is good to medium.The mercury porosimmetry curve shows a slightly coarse-thin skew.Combining the morphological characteristics of the mercury porosimmetry capillary pressure curve and the quantitative parameter characteristics of pore throats,the Yanchang Formation s micro pore structure is divided into types I,II,III,and IV.Tight oil reservoirs with type I and II pore structure characteristics are favorable.This study has reference significance for the later evaluation of tight sandstone reservoirs in Huangling mining area.展开更多
基金supported by the National Natural Science Foundation of China(Program No.41790442 and No.41772278)。
文摘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.
基金Shanghai Key Innovative Team of Cultural Heritage Conservation and the financial support from the National Sciences Foundation of China(Grant Nos.41977214 and 41572284)the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.Z013008)。
文摘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.
基金supported by the National Natural Science Foundation of China (Nos. 51504143 and 51674156)the SDUST Research Fund (No. 2015DJH101)the Major National R&D Projects of China (No. 2016ZX0 5027-001-006)。
文摘In this study, the differences in reservoir parameters, such as pore radius, throat radius, and pore-throat ratio, between the east and west subsags of the Lishui Sag are analyzed by using data obtained from a constant-rate mercury injection experiment. Furthermore, the quality of the reservoirs in the two subsags is systematically evaluated. Results show that the throat radius of the Lishui west subsag is larger than that of the east subsag, and this parameter has a positive correlation with reservoir quality. However, the pore-throat ratio of the east subsag is larger than that of the west subsag, which has an inverse relationship with reservoir quality. The main reasons for this reservoir difference can be attributed to sedimentation and diagenesis. The sedimentary facies types of the Lishui east subsag are the fan delta, shore lake, shallow lake, and shore shallow lake;their sandstone composition maturity is low;the clay mineral content is high;and the rock has undergone strong diagenesis. Therefore, the physical conditions of the reservoir are poor. However, the sandstones in the Lishui west subsag have weak cementation and compaction, mainly with an intergranular pore structure type, which leads to good connectivity between pores. Therefore, the storage performance and seepage capacity of the Lishui west subsag are better than those of the east subsag;the west subsag is the main area of oil and gas accumulation, as confirmed in the process of exploration and development.
基金Supported by the National Natural Science Foundation of China(No.51409261)
文摘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.
基金The funding was provided by the Deanship of Scientific Research at King Khalid University through Research Group Project[grant number RGP.1/157/42].
文摘Since the end of the 1990s,cryptosystems implemented on smart cards have had to deal with two main categories of attacks:side-channel attacks and fault injection attacks.Countermeasures have been developed and validated against these two types of attacks,taking into account a well-defined attacker model.This work focuses on small vulnerabilities and countermeasures related to the Elliptic Curve Digital Signature Algorithm(ECDSA)algorithm.The work done in this paper focuses on protecting the ECDSA algorithm against fault-injection attacks.More precisely,we are interested in the countermeasures of scalar multiplication in the body of the elliptic curves to protect against attacks concerning only a few bits of secret may be sufficient to recover the private key.ECDSA can be implemented in different ways,in software or via dedicated hardware or a mix of both.Many different architectures are therefore possible to implement an ECDSA-based system.For this reason,this work focuses mainly on the hardware implementation of the digital signature ECDSA.In addition,the proposed ECDSA architecture with and without fault detection for the scalar multiplication have been implemented on Xilinxfield programmable gate arrays(FPGA)platform(Virtex-5).Our implementation results have been compared and discussed.Our area,frequency,area overhead and frequency degradation have been compared and it is shown that the proposed architecture of ECDSA with fault detection for the scalar multiplication allows a trade-off between the hardware overhead and the security of the ECDSA.
基金supported by National Natural Science Foundation of China(No.11575159)National Natural Science Foundation of China(No.51206146)+1 种基金Zhejiang Provincial Natural Science Foundation of China(No.LY13B070004)Program for Zhejiang Leading Team of S&T Innovation(No.2013TD07)
文摘The electric energy injection from a pulsed power supply to a planar type of dielectric barrier discharge(DBD) reactor at atmospheric pressure was studied. Relations of the energy injection with barrier materials, barrier thickness, peak voltage, gap distance, electrode area,and operation temperature were experimentally investigated. The energy injection is a function of relative permittivity, barrier thickness, peak voltage, gap distance, and electrode area. The influence of operation temperature on energy injection is slight in the range of 27–300℃ but becomes obvious in the range of 300–500℃. A model was established using which the energy injection can be easily predicted.
文摘Based on scanning electron microscopy and mercury porosimmetry,a large number of experimental data of pores and pore throats of tight sandstone reservoirs are obtained,and the characteristics of pore types,capillary pressure curves and quantitative parameters of pore throats of Yanchang Formation in Huangling mining area are studied.The results show that the main reservoir space types of Yanchang Formation sandstone are primary intergranular pores and feldspar dissolution pores.The pore-throat structure is medium-small pore and thin-small throat type,and the sorting is good to medium.The mercury porosimmetry curve shows a slightly coarse-thin skew.Combining the morphological characteristics of the mercury porosimmetry capillary pressure curve and the quantitative parameter characteristics of pore throats,the Yanchang Formation s micro pore structure is divided into types I,II,III,and IV.Tight oil reservoirs with type I and II pore structure characteristics are favorable.This study has reference significance for the later evaluation of tight sandstone reservoirs in Huangling mining area.
