A time-harmonic equivalent current dipole model is proposed to simulate EEG source which deals with the problem concerning the capacitance effect. The expressions of potentials in both homogeneous infinite dielectric ...A time-harmonic equivalent current dipole model is proposed to simulate EEG source which deals with the problem concerning the capacitance effect. The expressions of potentials in both homogeneous infinite dielectric medium and dielectric sphere on the electroquasistatic condition are presented. The potential in a 3-layer inhomogeneous spherical head is computed by using this model. The influences on potential produced by time-harmonic character and permittivity are discussed. The results show that potentials in dielectric sphere are affected by frequency and permittivity.展开更多
Stress-dependence of the intrinsic time of viscoelastic materialsis investigated. The influence of stress level on the intrinsic timeis considered to be similar to that of temperature, pressure, solventcon- centration...Stress-dependence of the intrinsic time of viscoelastic materialsis investigated. The influence of stress level on the intrinsic timeis considered to be similar to that of temperature, pressure, solventcon- centration, damage and physical aging. Thetime-temperature-stress equivalence principle is proposed, byemploying which, the creep curves at different temperatures andstress level can be shifted into a master curve at referencetemperature and stress level.展开更多
In order to know about the rheological properties of rock in a long range of the time scale,method of increasing temperature was brought forward to accelerate the rheological process of rock,which could extend the tim...In order to know about the rheological properties of rock in a long range of the time scale,method of increasing temperature was brought forward to accelerate the rheological process of rock,which could extend the time scale of experimental test data.Firstly,based on the generalized linear viscoelastic constitutive equation with temperature variable,the creep behavior of rock was divided into three types according to the different strain dependences of the time,that is,Hookean deformation,Newtonian flow,and retarded elasticity.Then the general equivalence relationship between time parameter and temperature parameter was derived for each type of strain.Finally,the relation between time parameter and temperature parameter in the whole creep was considered and the general theory of time-temperature equivalence effect(TTEE) of rock was established.This research reveals: ①The temperature effect on the instantaneous strain could be modified through vertical shift.②The key point of the TTEE of Newtonian flow depends on whether in the study of linear viscoelastic behavior of rock change of temperature is completely equivalent to a shift of the logarithmic time scale or not.③By plotting the results of a creep experiment performed at different temperatures and comparing the curves obtained,one can decide whether the rock considered have TTEE.④The TTEE of the whole creep should satisfy that the horizontal shift function of Newtonian flow and retarded elasticity is consentaneous.展开更多
With the creep test data of granite taken from Three Gorges,the existence of time-temperature equivalence effect(TTEE) of granite is investigated.Based on the creep test data at different temperatures,which are 20 ℃,...With the creep test data of granite taken from Three Gorges,the existence of time-temperature equivalence effect(TTEE) of granite is investigated.Based on the creep test data at different temperatures,which are 20 ℃,60 ℃,80 ℃,100 ℃,200 ℃,300 ℃,four-component viscoelastic Burgers model is presented to characterize the creep curves.The parameters of elasticity modulus and viscosity coefficient in the constitutive model at different temperatures and their functional dependences on temperature are obtained.Then,according to the basic theory of TTEE presented in research(I),the TTEE of granite is investigated through modifying the compliance curves with vertical shift function and checking the coincidence of the modified curves with horizontal shift functions.It is concluded that:① Burgers model could appropriately characterize the creep property of granite in a short time scale.② Both elastic modulus and viscosity coefficient in the Burgers model decay exponentially with temperature.③ The coincidence of the curves at different temperatures after vertical shift modification and horizontal shift is fine,which indicates the existence of TTEE of granite.④The master curves which reflect the long time scale test data at temperatures 20 ℃,100 ℃,200 ℃ are obtained.展开更多
In this paper,the equivalent force inside the source which produces a large area deformation field is calculated by using the records of residual deformation,S wave radiation of shear dislocation source and Green func...In this paper,the equivalent force inside the source which produces a large area deformation field is calculated by using the records of residual deformation,S wave radiation of shear dislocation source and Green function of the Lancang-Gengma earthquake.Under the action of equivalent force whose intensity was 1.103×1013 N,the crust derm of northeast segment of seismic fault had finished the upraise and formed permanent irrecoverable deformation within 20.46 min after the major earthquake occurred.The authors indicate that the residual deformation would split into 2 deformation fields with different propagation velocities and different directions in the Song-distance propagation process.展开更多
Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects...Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects, site-specific effects may be introduced from vegetation changes, site physical changes, measurement technique, and sensor changes. This paper examines changes in Utah＇s snowpack conditions over the past decade compared with all previous measurement years, focusing on the 15 snow courses with the longest observational record within the state of Utah. Although patterns in snowpack data consistent with those that would be expected due to temperature h as greater declines at lower elevations and latitudes--were not identified, snow water equivalent decreased at sites with significant increases in vegetation coverage. Additionally, we provide a list of 22 snow courses in Utah that are best-suited for long-term climate analysis.展开更多
介绍了中国《建筑隔震设计标准》(GB/T 51408—2021)(以下简称《隔标》)和美国Minimum design loads and associated criteria for buildings and other structures(ASCE 7-16)隔震设计的相关要求,并针对基于《建筑抗震设计规范》(GB 50...介绍了中国《建筑隔震设计标准》(GB/T 51408—2021)(以下简称《隔标》)和美国Minimum design loads and associated criteria for buildings and other structures(ASCE 7-16)隔震设计的相关要求,并针对基于《建筑抗震设计规范》(GB 50011—2010)(2016年版)(以下简称《抗规》)设计的某9度区近场隔震结构,进行了两国规范的设计对比。按《抗规》设计的隔震结构,仍然能满足《隔标》的设计要求。ASCE 7-16对于隔震支座考虑了老化和环境、测试、制造等因素引起的性能参数变化,并按隔震支座的上限及下限属性进行了结构设计。基于相同地震概率水准(50年超越概率2%)的设计对比研究表明,ASCE 7-16的等效侧力法计算值高于《隔标》,按ASCE 7-16要求选择的地震波反应谱明显高于《隔标》,其时程分析结果也大于中国规范,对隔震支座的性能要求更高。展开更多
为探究冻融循环对食用菌预制菌汤的品质影响,本文以鲜菌汤为参照,对比了冻融过程中微生物数量、菌汤色泽、可溶性蛋白、还原糖、总酚含量等基本指标的变化,并基于超高效液相检测和气相色谱-质谱法分析冻融过程菌汤等鲜度和挥发性风味物...为探究冻融循环对食用菌预制菌汤的品质影响,本文以鲜菌汤为参照,对比了冻融过程中微生物数量、菌汤色泽、可溶性蛋白、还原糖、总酚含量等基本指标的变化,并基于超高效液相检测和气相色谱-质谱法分析冻融过程菌汤等鲜度和挥发性风味物质差异。研究表明,首次冻融大幅减少了菌汤的还原糖、总酚和总氨基酸含量,显著降低了菌汤等鲜度和挥发性成分含量,综合影响了菌汤的成分与风味。进一步通过冻融次数(1~5次)之间的对比,反复冻融3次菌汤可溶性蛋白含量相较于冻融1~2次显著降低(P<0.05),此外,等鲜度由1~2次冻融的0.441~0.450 g MSG/100 g直接下降至0.407 g MSG/100 g,同时微生物开始检出。在此后4~5次冻融过程中,虽然菌汤总酚、总氨基酸含量和等鲜度相对稳定,但核苷酸、可溶性蛋白和挥发性成分不断减少且菌落总数不断升高。因此,预制菌汤若需冻融处理则应控制在2次内为宜。展开更多
基金This work was supported by the Science and Technology Foundation of Guizhou Province under Grant No.20052005.
文摘A time-harmonic equivalent current dipole model is proposed to simulate EEG source which deals with the problem concerning the capacitance effect. The expressions of potentials in both homogeneous infinite dielectric medium and dielectric sphere on the electroquasistatic condition are presented. The potential in a 3-layer inhomogeneous spherical head is computed by using this model. The influences on potential produced by time-harmonic character and permittivity are discussed. The results show that potentials in dielectric sphere are affected by frequency and permittivity.
基金the Nalional Natural Science Foundation of China (No.19632030,50003005)the Education Committee of Hunan Province (No.99C122)
文摘Stress-dependence of the intrinsic time of viscoelastic materialsis investigated. The influence of stress level on the intrinsic timeis considered to be similar to that of temperature, pressure, solventcon- centration, damage and physical aging. Thetime-temperature-stress equivalence principle is proposed, byemploying which, the creep curves at different temperatures andstress level can be shifted into a master curve at referencetemperature and stress level.
基金Supported by the Long-term evolution of stability and permeability of high-level radioactive waste repository surrounding rock under THMC coupling process
文摘In order to know about the rheological properties of rock in a long range of the time scale,method of increasing temperature was brought forward to accelerate the rheological process of rock,which could extend the time scale of experimental test data.Firstly,based on the generalized linear viscoelastic constitutive equation with temperature variable,the creep behavior of rock was divided into three types according to the different strain dependences of the time,that is,Hookean deformation,Newtonian flow,and retarded elasticity.Then the general equivalence relationship between time parameter and temperature parameter was derived for each type of strain.Finally,the relation between time parameter and temperature parameter in the whole creep was considered and the general theory of time-temperature equivalence effect(TTEE) of rock was established.This research reveals: ①The temperature effect on the instantaneous strain could be modified through vertical shift.②The key point of the TTEE of Newtonian flow depends on whether in the study of linear viscoelastic behavior of rock change of temperature is completely equivalent to a shift of the logarithmic time scale or not.③By plotting the results of a creep experiment performed at different temperatures and comparing the curves obtained,one can decide whether the rock considered have TTEE.④The TTEE of the whole creep should satisfy that the horizontal shift function of Newtonian flow and retarded elasticity is consentaneous.
基金Long-term evolution of stability and permeability of high-level radioactive waste repository surrounding rock under THMC coupling process
文摘With the creep test data of granite taken from Three Gorges,the existence of time-temperature equivalence effect(TTEE) of granite is investigated.Based on the creep test data at different temperatures,which are 20 ℃,60 ℃,80 ℃,100 ℃,200 ℃,300 ℃,four-component viscoelastic Burgers model is presented to characterize the creep curves.The parameters of elasticity modulus and viscosity coefficient in the constitutive model at different temperatures and their functional dependences on temperature are obtained.Then,according to the basic theory of TTEE presented in research(I),the TTEE of granite is investigated through modifying the compliance curves with vertical shift function and checking the coincidence of the modified curves with horizontal shift functions.It is concluded that:① Burgers model could appropriately characterize the creep property of granite in a short time scale.② Both elastic modulus and viscosity coefficient in the Burgers model decay exponentially with temperature.③ The coincidence of the curves at different temperatures after vertical shift modification and horizontal shift is fine,which indicates the existence of TTEE of granite.④The master curves which reflect the long time scale test data at temperatures 20 ℃,100 ℃,200 ℃ are obtained.
文摘In this paper,the equivalent force inside the source which produces a large area deformation field is calculated by using the records of residual deformation,S wave radiation of shear dislocation source and Green function of the Lancang-Gengma earthquake.Under the action of equivalent force whose intensity was 1.103×1013 N,the crust derm of northeast segment of seismic fault had finished the upraise and formed permanent irrecoverable deformation within 20.46 min after the major earthquake occurred.The authors indicate that the residual deformation would split into 2 deformation fields with different propagation velocities and different directions in the Song-distance propagation process.
文摘Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects, site-specific effects may be introduced from vegetation changes, site physical changes, measurement technique, and sensor changes. This paper examines changes in Utah＇s snowpack conditions over the past decade compared with all previous measurement years, focusing on the 15 snow courses with the longest observational record within the state of Utah. Although patterns in snowpack data consistent with those that would be expected due to temperature h as greater declines at lower elevations and latitudes--were not identified, snow water equivalent decreased at sites with significant increases in vegetation coverage. Additionally, we provide a list of 22 snow courses in Utah that are best-suited for long-term climate analysis.
文摘介绍了中国《建筑隔震设计标准》(GB/T 51408—2021)(以下简称《隔标》)和美国Minimum design loads and associated criteria for buildings and other structures(ASCE 7-16)隔震设计的相关要求,并针对基于《建筑抗震设计规范》(GB 50011—2010)(2016年版)(以下简称《抗规》)设计的某9度区近场隔震结构,进行了两国规范的设计对比。按《抗规》设计的隔震结构,仍然能满足《隔标》的设计要求。ASCE 7-16对于隔震支座考虑了老化和环境、测试、制造等因素引起的性能参数变化,并按隔震支座的上限及下限属性进行了结构设计。基于相同地震概率水准(50年超越概率2%)的设计对比研究表明,ASCE 7-16的等效侧力法计算值高于《隔标》,按ASCE 7-16要求选择的地震波反应谱明显高于《隔标》,其时程分析结果也大于中国规范,对隔震支座的性能要求更高。
文摘为探究冻融循环对食用菌预制菌汤的品质影响,本文以鲜菌汤为参照,对比了冻融过程中微生物数量、菌汤色泽、可溶性蛋白、还原糖、总酚含量等基本指标的变化,并基于超高效液相检测和气相色谱-质谱法分析冻融过程菌汤等鲜度和挥发性风味物质差异。研究表明,首次冻融大幅减少了菌汤的还原糖、总酚和总氨基酸含量,显著降低了菌汤等鲜度和挥发性成分含量,综合影响了菌汤的成分与风味。进一步通过冻融次数(1~5次)之间的对比,反复冻融3次菌汤可溶性蛋白含量相较于冻融1~2次显著降低(P<0.05),此外,等鲜度由1~2次冻融的0.441~0.450 g MSG/100 g直接下降至0.407 g MSG/100 g,同时微生物开始检出。在此后4~5次冻融过程中,虽然菌汤总酚、总氨基酸含量和等鲜度相对稳定,但核苷酸、可溶性蛋白和挥发性成分不断减少且菌落总数不断升高。因此,预制菌汤若需冻融处理则应控制在2次内为宜。
