This paper presents a semi-analytical method to solve one dimensional consolidation problem by taking consideration of varied compressibility of soil under cyclic loading. In the method, soil stratum is divided equall...This paper presents a semi-analytical method to solve one dimensional consolidation problem by taking consideration of varied compressibility of soil under cyclic loading. In the method, soil stratum is divided equally into n layers while load and consolidation time are also divided into small parts and time intervals accordingly. The problem of one-dimensional consolidation of soil stratum under cyclic loading can then be dealt with at each time interval as one-dimensional linear consolidation of multi-layered soils under constant loading. The compression or rebounding of each soil layer can be judged by the effective stress of the layer. When the effective stress is larger than that in the last time interval, the soil layer is compressed, and when it is smaller, the soil layer rebounds. Thus, appropriate compressibility can be chosen and the consolidation of the layered system can be analyzed by the available analytical linear consolidation theory. Based on the semi-analytical method, a computer program was developed and the behavior of one-dimensional consolidation of soil with varied compressibility under cyclic loading was investigated, and compared with the available consolidation theory which takes no consideration of varied compressibility of soil under cyclic loading. The results showed that by taking the variable compressibility into account, the rate of consolidation of soil was greater than the one predicted by conventional consolidation theory.展开更多
Based on the model test of podded propulsor in straight forward motion, the paper presents the results of the effects of geometric parameters on the propulsive characteristics of podded propulsors in viscous flow. Thr...Based on the model test of podded propulsor in straight forward motion, the paper presents the results of the effects of geometric parameters on the propulsive characteristics of podded propulsors in viscous flow. Three main geometrical parameters, i.e. pod diameter, strut distance from the propeller plane, and the maximum thickness of strut are studied with systematically varied geometry while the parameters of propeller blades are fixed. The RANS approach is adopted to study the steady perfomaance using the Huent software package. While the interactions of the propeller blades with the pod and strut are time-dependent by nature, the mixing plane model is employed to predict the steady perfomlance. In considera- tion of the complexity, the research does not deal with the effects of the combination of such three main parameters.展开更多
Four diets were formulated to study the influence of varying crude protein levels on the performance, egg quality, serum and haematological characteristics at the first phase of laying cycle of sixty Bovan Nera laying...Four diets were formulated to study the influence of varying crude protein levels on the performance, egg quality, serum and haematological characteristics at the first phase of laying cycle of sixty Bovan Nera laying birds that were randomly allotted to dietary treatments. The four experimental diets had five replicates each and three birds per repli-cate. Diet 1 contained 14% crude protein (CP), while diet 2 contained 15% CP, diets 3 and 4 contained 16% and 17% CP respectively. The experimental birds were fed for 10 weeks and the data collected were statistically analysed. Apparent variations recorded for all the performance characteristics such as Egg number, Hen-day production, Feed Conversion Ratio (FCR) and weight gain were significantly different (p < 0.05). The best FCR value were recorded by birds fed 17% CP (3.45), while the highest weight gain mean value were also recorded by birds fed 17% CP value. Findings indicated a direct relationship between dietary crude protein values and performance.展开更多
Parts with varied curvature features play increasingly critical roles in engineering, and are often machined under high-speed continuous-path running mode to ensure the machining efficiency. However, the continuous-pa...Parts with varied curvature features play increasingly critical roles in engineering, and are often machined under high-speed continuous-path running mode to ensure the machining efficiency. However, the continuous-path running trajectory error is significant during high-feed-speed machining, which seriously restricts the machining precision for such parts with varied curvature features. In order to reduce the continuous-path running trajectory error without sacrificing the machining efficiency, a pre-compensation method for the trajectory error is proposed. Based on the formation mechanism of the continuous-path running trajectory error analyzed, this error is estimated in advance by approximating the desired toolpath with spline curves. Then, an iterative error pre-compensation method is presented. By machining with the regenerated toolpath after pre-compensation instead of the uncompensated toolpath, the continuous-path running trajectory error can be effectively decreased without the reduction of the feed speed. To demonstrate the feasibility of the proposed pre-compensation method, a heart curve toolpath that possesses varied curvature features is employed. Experimental results indicate that compared with the uncompensated processing trajectory, the maximum and average machining errors for the pre-compensated processing trajectory are reduced by 67.19% and 82.30%, respectively. An easy to implement solution for high efficiency and high precision machining of the parts with varied curvature features is provided.展开更多
Gas diffusion in the shale matrix has a dominant effect on late-stage production from shale gas reservoirs.However,adequate research on the mechanisms and contributions of gas diffusion for varied pore size population...Gas diffusion in the shale matrix has a dominant effect on late-stage production from shale gas reservoirs.However,adequate research on the mechanisms and contributions of gas diffusion for varied pore size populations in shale matrix under recreated in situ stress is lacking.We report gas-diffusion measurements under constant in situ stress but variable gas pressures for contrasting non-adsorbent(helium(He))and adsorbed(methane(CH_(4)))gases to investigate the impact of effective stress on the evolution of dominant mechanisms of diffusion.An intact sample replicates true pore-network topology and diffusion paths.An integrated diffusion model is proposed that combines the effects of slip flow,Knudsen flow,and surface diffusion to constrain the evolution of these flow regimes and their respective contributions to the observational data.Finally,a probability density function(PDF)is employed to separate the gas content distributions of macropores and micropores from the total gas content and to investigate gas contributions in various pores.The results reveal that the diffusion coefficients of both He and CH_(4)in macropores and micropores increase with gas pressure but decrease with increasing effective stress.The diffusion coefficients of He and CH_(4)are different in macropores but remain nearly the same in micropores.The diffusion coefficients of slip flow and surface diffusion increase with decreasing effective stress except for CH_(4)diffusion in the micropores,while the evolution of Knudsen diffusion shows the opposite trend.Slip flow plays a dominant role in He and CH_(4)diffusion within macropores(pore size 45 nm).Knudsen diffusion gradually becomes significant for He diffusion in the micropores(pore size 4 nm),conversely,for CH_(4)diffusion in the micropores,surface diffusion becomes significant.Related to gas production from reservoirs,the contributions of the micropores will increase gradually with the duration of gas recovery,indicating the significant role of gas diffusion in micropores to steady supply during latestage production.展开更多
The built-in electric fields within a varied doping GaAs photocathode may promote the transport of electrons from the bulk to the surface, thus the quantum efficiency of the cathode can be enhanced remarkably. But thi...The built-in electric fields within a varied doping GaAs photocathode may promote the transport of electrons from the bulk to the surface, thus the quantum efficiency of the cathode can be enhanced remarkably. But this enhancement, which might be due to the increase in either the number or the energy of electrons reaching the surface, is not clear at present. In this paper, the energy distributions of electrons in a varied doping photocathode and uniform doping photocathode before and after escaping from the cathode surface are analysed, and the number of electrons escaping from the surface in different cases is calculated for the two kinds of photocathodes. The results indicate that the varied doping structure can not only increase the number of electrons reaching the surface but also cause an offset of the electron energy distribution to high energy. That is the root reason for the enhancement of the quantum efficiency of a varied doping GaAs photocathode.展开更多
The wave equations about displacement, velocity, stress and strain in functionally gradient material （FGM） with constituents varied continuously and smoothly were established. Four kinds of waves are of linear secon...The wave equations about displacement, velocity, stress and strain in functionally gradient material （FGM） with constituents varied continuously and smoothly were established. Four kinds of waves are of linear second-order partial differential equation of hyperbolic type and have the same characteristic curve at the plane of X,t. In general, the varying mode of stress is different from that of displacement and velocity at the front of wave. But in a special case that the product of density p and elastic modulus E of the material remains unchanged, the three wave equations have a similar expression and they have a similar varying mode in the front of wave.展开更多
Estimation of velocity profile within mud depth is a long-standing and essential problem in debris flow dynamics.Until now,various velocity profiles have been proposed based on the fitting analysis of experimental mea...Estimation of velocity profile within mud depth is a long-standing and essential problem in debris flow dynamics.Until now,various velocity profiles have been proposed based on the fitting analysis of experimental measurements,but these are often limited by the observation conditions,such as the number of configured sensors.Therefore,the resulting linear velocity profiles usually exhibit limitations in reproducing the temporal-varied and nonlinear behavior during the debris flow process.In this study,we present a novel approach to explore the debris flow velocity profile in detail upon our previous 3D-HBPSPH numerical model,i.e.,the three-dimensional Smoothed Particle Hydrodynamic model incorporating the Herschel-Bulkley-Papanastasiou rheology.Specifically,we propose a stratification aggregation algorithm for interpreting the details of SPH particles,which enables the recording of temporal velocities of debris flow at different mud depths.To analyze the velocity profile,we introduce a logarithmic-based nonlinear model with two key parameters,that a controlling the shape of velocity profile and b concerning its temporal evolution.We verify the proposed velocity profile and explore its sensitivity using 34 sets of velocity data from three individual flume experiments in previous literature.Our results demonstrate that the proposed temporalvaried nonlinear velocity profile outperforms the previous linear profiles.展开更多
The effects of 6-benzylaminopurine （6-BA） on several physiological indexes of Caryota mitis and C. obtusa seedlings treated at varied temperatures were conducted, the leaves of the two palm species were sprayed with...The effects of 6-benzylaminopurine （6-BA） on several physiological indexes of Caryota mitis and C. obtusa seedlings treated at varied temperatures were conducted, the leaves of the two palm species were sprayed with 0, 25, 50 and 100 mg · L1 6-BA solutions, the activities of superoxide dismutase （SOD）, peroxidase （POD）, and the contents of malondialdehyde （MDA）, proline, soluble protein, chlorophyll and chlorophyll a/b were determined under 25 ℃, 5 ℃ and 25 ℃ for 24 h, respectively. The dynamics of a series of important physiological components derived from the leaves were studied. It was indicated that all the above mentioned physiological indexes varied with different concentrations of 6-BA and temperature. The fuzzy comprehensive evaluation values for different concentrations of 6-BA at the recovery temperature 25℃ were 0.33, 0.28, 0.92 and 0.33, respectively for C. mitis, and 0.20, 0.49, 0.56 and 0.63, respectively for C. obtusa. It was concluded that leaves sprayed with different concentrations of 6-BA could affect the cold tolerance of palm seedlings. The optimal concentration of 6-BA was different for different palm species.展开更多
We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical stud...We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.展开更多
Combining real accelerating genetic algorithm(RAGA) with the optimization design of multi-hole and varied diameter pipe, the authors solved the problem of optimizing multi-dimensional parameters at the same time. In w...Combining real accelerating genetic algorithm(RAGA) with the optimization design of multi-hole and varied diameter pipe, the authors solved the problem of optimizing multi-dimensional parameters at the same time. In which the advanced convergence and easily to run into partial optimization were avoid. Applied the RAGA to solving the problem in the optimization design of fixed piping sprinkler irrigation system. The optimized parameters, such as diameters and the length of pipe were calculated and the result was reasonable, which provides as a reference to readers who work at related research.展开更多
In this paper, we give some sufficient conditions of the instability for the fourth order linear differential equation with varied coefficient, at least one of the characteristic roots of which has positive real part,...In this paper, we give some sufficient conditions of the instability for the fourth order linear differential equation with varied coefficient, at least one of the characteristic roots of which has positive real part, by means of Liapunov's second method.展开更多
The structure and function of protein are strongly pH-dependence. However, the inonization state of the protein varied with the pH value also depends on the local structure
Finding clusters in data is a challenging problem especially when the clusters are being of widely varied shapes, sizes, and densities. Herein a new scalable clustering technique which addresses all these issues is pr...Finding clusters in data is a challenging problem especially when the clusters are being of widely varied shapes, sizes, and densities. Herein a new scalable clustering technique which addresses all these issues is proposed. In data mining, the purpose of data clustering is to identify useful patterns in the underlying dataset. Within the last several years, many clustering algorithms have been proposed in this area of research. Among all these proposed methods, density clustering methods are the most important due to their high ability to detect arbitrary shaped clusters. Moreover these methods often show good noise-handling capabilities, where clusters are defined as regions of typical densities separated by low or no density regions. In this paper, we aim at enhancing the well-known algorithm DBSCAN, to make it scalable and able to discover clusters from uneven datasets in which clusters are regions of homogenous densities. We achieved the scalability of the proposed algorithm by using the k-means algorithm to get initial partition of the dataset, applying the enhanced DBSCAN on each partition, and then using a merging process to get the actual natural number of clusters in the underlying dataset. This means the proposed algorithm consists of three stages. Experimental results using synthetic datasets show that the proposed clustering algorithm is faster and more scalable than the enhanced DBSCAN counterpart.展开更多
Enrichment of copper to the culture mediumcould enhance the plant regeneration from cal-lus of indica rice variety Qiugui’ai 11. Westudied the effect of copper on plant regenera-tion of other rice varieties.Calli of ...Enrichment of copper to the culture mediumcould enhance the plant regeneration from cal-lus of indica rice variety Qiugui’ai 11. Westudied the effect of copper on plant regenera-tion of other rice varieties.Calli of 14 indica and 2 japonica varietieswere induced from disinfected mature embryoson an agar-gelled medium containing Nbasal展开更多
The zero-inertia model is widely used for simulating surface flow in irrigation systems.This model is accurate when inflow discharge is constant.However,simulation of irrigation systems with rapidly varied inflow disc...The zero-inertia model is widely used for simulating surface flow in irrigation systems.This model is accurate when inflow discharge is constant.However,simulation of irrigation systems with rapidly varied inflow discharge is needed due to the development of real time control irrigation technology.Hence,the objective of this study is to validate the zero-inertia model with rapidly varied inflow discharge.For this purpose,twenty-three border irrigation tests at a range of inflow changes on different field slopes and roughness coefficients were conducted.Then,the sensitivity analyses of bed slope,infiltration parameters,and roughness coefficient were examined.The results indicate that the zero-inertia model predictions are in good agreement with field data in both advance/recession times and flow depths.The infiltration parameters were the most sensitive input variable of the zero-inertia model.The input variables have a more considerable impact on the recession phase than the advance phase.展开更多
We tackle the problem of a biped running over varied and unknown terrain.Running is a necessary skill for a biped moving fast,but it increases the challenge of dynamic balance,especially when a biped is running on var...We tackle the problem of a biped running over varied and unknown terrain.Running is a necessary skill for a biped moving fast,but it increases the challenge of dynamic balance,especially when a biped is running on varied terrain without terrain information(due to the difficulty and cost of obtaining the terrain information in a timely manner).To address this issue,a new dynamic indicator called the sustainable running criterion is developed.The main idea is to sustain a running motion without falling by maintaining the system states within a running-feasible set,instead of running on a periodic limit cycle gait in the traditional way.To meet the precondition of the criterion,the angular moment about the center of gravity(COG) is restrained close to zero at the end of the stance phase.Then to ensure a small state jump at touchdown on the unknown terrain,the velocity of the swing foot is restrained within a specific range at the end of the flight phase.Finally,the position and velocity of the COG are driven into the running-feasible set.A five-link biped with underactuated point foot is considered in simulations.It is able to run over upward and downward terrain with a height difference of 0.15 m,which shows the effectiveness of our control scheme.展开更多
The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process.To analyze the rotation state,cutting performance,and adaptability of disc ...The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process.To analyze the rotation state,cutting performance,and adaptability of disc cutters during shield tunneling in soft–hard varied strata,the Holmquist Johnson Cook and Federal Highway Administration constitutive models are introduced to numerically simulate the failure process of materials on the excavation face and to calculate the load of disc cutters.Additionally,the parameters of the models are modified based on laboratory disc cutter excavation test results.The results of numerical calculation can reflect the load level and the behavior of the disc cutters during operation.The tangential loads of the disc cutters during the cutting of four typical soft-strata excavation face models are numerically calculated,thus providing reference values for the starting torque of the disc cutters.A greater penetration is suggested for soft-strata tunneling to allow the disc cutters to rotate smoothly and continuously as well as to guarantee a better cutting effect.The disc cutters in the center of the cutterhead should be specified with a lower starting torque to prevent uneven wear,rotation stagnation,cutterhead clogging,and other adverse phenomena.展开更多
Let D be a digital manifold, J the subset of non-empty of D; and let A<sub>1</sub>, A<sub>2</sub>, …, A<sub>m</sub> be m real numbers with A<sub>1</sub>【A<sub>2&...Let D be a digital manifold, J the subset of non-empty of D; and let A<sub>1</sub>, A<sub>2</sub>, …, A<sub>m</sub> be m real numbers with A<sub>1</sub>【A<sub>2</sub>【…【A<sub>m</sub>. Supposing function f<sub>J</sub>: J → A<sub>1</sub>,…, A<sub>m</sub>, we want to find a function f<sub>D</sub>: D→{A<sub>1</sub>…, A<sub>m</sub>}, such that f<sub>D</sub> is gradual variation on D, having f<sub>D</sub>（x）=f<sub>J</sub>（x）, x∈J. Such f<sub>D</sub> is called the gradually varied extension or interpolation of f<sub>J</sub>.展开更多
Filling is an important part in pattern recognition and computer vision. In the discrete plane （grid of plane）∑<sub>2</sub>, fill means 'determination of the region D enclosed by the simple closed c...Filling is an important part in pattern recognition and computer vision. In the discrete plane （grid of plane）∑<sub>2</sub>, fill means 'determination of the region D enclosed by the simple closed curve J which is given beforehand'. In other words, if the valuation of the point on the contour J is 1, we want to do a valuation for ∑<sub>2</sub> to make the valuation of the point p be 1 iff point p belongs to D.展开更多
文摘This paper presents a semi-analytical method to solve one dimensional consolidation problem by taking consideration of varied compressibility of soil under cyclic loading. In the method, soil stratum is divided equally into n layers while load and consolidation time are also divided into small parts and time intervals accordingly. The problem of one-dimensional consolidation of soil stratum under cyclic loading can then be dealt with at each time interval as one-dimensional linear consolidation of multi-layered soils under constant loading. The compression or rebounding of each soil layer can be judged by the effective stress of the layer. When the effective stress is larger than that in the last time interval, the soil layer is compressed, and when it is smaller, the soil layer rebounds. Thus, appropriate compressibility can be chosen and the consolidation of the layered system can be analyzed by the available analytical linear consolidation theory. Based on the semi-analytical method, a computer program was developed and the behavior of one-dimensional consolidation of soil with varied compressibility under cyclic loading was investigated, and compared with the available consolidation theory which takes no consideration of varied compressibility of soil under cyclic loading. The results showed that by taking the variable compressibility into account, the rate of consolidation of soil was greater than the one predicted by conventional consolidation theory.
基金supported by the Fundamental Research Funds for the Central Universities (Grant No.HEUCFT1001)the"Knowledge-based Ship Design Hyper-Integrated Plat form(KSHIP)",a Key Project of the Ministry of Education and the Ministry of Finance of China
文摘Based on the model test of podded propulsor in straight forward motion, the paper presents the results of the effects of geometric parameters on the propulsive characteristics of podded propulsors in viscous flow. Three main geometrical parameters, i.e. pod diameter, strut distance from the propeller plane, and the maximum thickness of strut are studied with systematically varied geometry while the parameters of propeller blades are fixed. The RANS approach is adopted to study the steady perfomaance using the Huent software package. While the interactions of the propeller blades with the pod and strut are time-dependent by nature, the mixing plane model is employed to predict the steady perfomlance. In considera- tion of the complexity, the research does not deal with the effects of the combination of such three main parameters.
文摘Four diets were formulated to study the influence of varying crude protein levels on the performance, egg quality, serum and haematological characteristics at the first phase of laying cycle of sixty Bovan Nera laying birds that were randomly allotted to dietary treatments. The four experimental diets had five replicates each and three birds per repli-cate. Diet 1 contained 14% crude protein (CP), while diet 2 contained 15% CP, diets 3 and 4 contained 16% and 17% CP respectively. The experimental birds were fed for 10 weeks and the data collected were statistically analysed. Apparent variations recorded for all the performance characteristics such as Egg number, Hen-day production, Feed Conversion Ratio (FCR) and weight gain were significantly different (p < 0.05). The best FCR value were recorded by birds fed 17% CP (3.45), while the highest weight gain mean value were also recorded by birds fed 17% CP value. Findings indicated a direct relationship between dietary crude protein values and performance.
基金Supported by National Natural Science Foundation of China(Grant Nos.51575087,51205041)Science Fund for Creative Research Groups(Grant No.51321004)+1 种基金Basic Research Foundation of Key Laboratory of Liaoning Educational Committee,China(Grant No.LZ2014003)Research Project of Ministry of Education of China(Grant No.113018A)
文摘Parts with varied curvature features play increasingly critical roles in engineering, and are often machined under high-speed continuous-path running mode to ensure the machining efficiency. However, the continuous-path running trajectory error is significant during high-feed-speed machining, which seriously restricts the machining precision for such parts with varied curvature features. In order to reduce the continuous-path running trajectory error without sacrificing the machining efficiency, a pre-compensation method for the trajectory error is proposed. Based on the formation mechanism of the continuous-path running trajectory error analyzed, this error is estimated in advance by approximating the desired toolpath with spline curves. Then, an iterative error pre-compensation method is presented. By machining with the regenerated toolpath after pre-compensation instead of the uncompensated toolpath, the continuous-path running trajectory error can be effectively decreased without the reduction of the feed speed. To demonstrate the feasibility of the proposed pre-compensation method, a heart curve toolpath that possesses varied curvature features is employed. Experimental results indicate that compared with the uncompensated processing trajectory, the maximum and average machining errors for the pre-compensated processing trajectory are reduced by 67.19% and 82.30%, respectively. An easy to implement solution for high efficiency and high precision machining of the parts with varied curvature features is provided.
基金Open Foundation of National Energy shale gas R&D(experiment)center(2022-KFKT-12)the research delivered partial results under the support of the National Key R&D Program of China(2021YFC2902101)+2 种基金National Natural Science Foundation of China(12002081)the National Natural Science Foundation of China(Grant No.12002081)the 111 Project(B17009).
文摘Gas diffusion in the shale matrix has a dominant effect on late-stage production from shale gas reservoirs.However,adequate research on the mechanisms and contributions of gas diffusion for varied pore size populations in shale matrix under recreated in situ stress is lacking.We report gas-diffusion measurements under constant in situ stress but variable gas pressures for contrasting non-adsorbent(helium(He))and adsorbed(methane(CH_(4)))gases to investigate the impact of effective stress on the evolution of dominant mechanisms of diffusion.An intact sample replicates true pore-network topology and diffusion paths.An integrated diffusion model is proposed that combines the effects of slip flow,Knudsen flow,and surface diffusion to constrain the evolution of these flow regimes and their respective contributions to the observational data.Finally,a probability density function(PDF)is employed to separate the gas content distributions of macropores and micropores from the total gas content and to investigate gas contributions in various pores.The results reveal that the diffusion coefficients of both He and CH_(4)in macropores and micropores increase with gas pressure but decrease with increasing effective stress.The diffusion coefficients of He and CH_(4)are different in macropores but remain nearly the same in micropores.The diffusion coefficients of slip flow and surface diffusion increase with decreasing effective stress except for CH_(4)diffusion in the micropores,while the evolution of Knudsen diffusion shows the opposite trend.Slip flow plays a dominant role in He and CH_(4)diffusion within macropores(pore size 45 nm).Knudsen diffusion gradually becomes significant for He diffusion in the micropores(pore size 4 nm),conversely,for CH_(4)diffusion in the micropores,surface diffusion becomes significant.Related to gas production from reservoirs,the contributions of the micropores will increase gradually with the duration of gas recovery,indicating the significant role of gas diffusion in micropores to steady supply during latestage production.
基金supported by the National Natural Science Foundation of China (Grant No.60678043) the Research and Innovation Plan for Graduate Students of Jiangsu Higher Education Institutions of China (Grant No. CX09B-096Z)
文摘The built-in electric fields within a varied doping GaAs photocathode may promote the transport of electrons from the bulk to the surface, thus the quantum efficiency of the cathode can be enhanced remarkably. But this enhancement, which might be due to the increase in either the number or the energy of electrons reaching the surface, is not clear at present. In this paper, the energy distributions of electrons in a varied doping photocathode and uniform doping photocathode before and after escaping from the cathode surface are analysed, and the number of electrons escaping from the surface in different cases is calculated for the two kinds of photocathodes. The results indicate that the varied doping structure can not only increase the number of electrons reaching the surface but also cause an offset of the electron energy distribution to high energy. That is the root reason for the enhancement of the quantum efficiency of a varied doping GaAs photocathode.
基金the National Natural Science Foundation of China (No.50272046)
文摘The wave equations about displacement, velocity, stress and strain in functionally gradient material （FGM） with constituents varied continuously and smoothly were established. Four kinds of waves are of linear second-order partial differential equation of hyperbolic type and have the same characteristic curve at the plane of X,t. In general, the varying mode of stress is different from that of displacement and velocity at the front of wave. But in a special case that the product of density p and elastic modulus E of the material remains unchanged, the three wave equations have a similar expression and they have a similar varying mode in the front of wave.
基金supported by the National Natural Science Foundation of China(Grant No.52078493)the Natural Science Foundation of Hunan Province(Grant No.2022JJ30700)+2 种基金the Natural Science Foundation for Excellent Young Scholars of Hunan(Grant No.2021JJ20057)the Science and Technology Plan Project of Changsha(Grant No.kq2305006)the Innovation Driven Program of Central South University(Grant No.2023CXQD033).
文摘Estimation of velocity profile within mud depth is a long-standing and essential problem in debris flow dynamics.Until now,various velocity profiles have been proposed based on the fitting analysis of experimental measurements,but these are often limited by the observation conditions,such as the number of configured sensors.Therefore,the resulting linear velocity profiles usually exhibit limitations in reproducing the temporal-varied and nonlinear behavior during the debris flow process.In this study,we present a novel approach to explore the debris flow velocity profile in detail upon our previous 3D-HBPSPH numerical model,i.e.,the three-dimensional Smoothed Particle Hydrodynamic model incorporating the Herschel-Bulkley-Papanastasiou rheology.Specifically,we propose a stratification aggregation algorithm for interpreting the details of SPH particles,which enables the recording of temporal velocities of debris flow at different mud depths.To analyze the velocity profile,we introduce a logarithmic-based nonlinear model with two key parameters,that a controlling the shape of velocity profile and b concerning its temporal evolution.We verify the proposed velocity profile and explore its sensitivity using 34 sets of velocity data from three individual flume experiments in previous literature.Our results demonstrate that the proposed temporalvaried nonlinear velocity profile outperforms the previous linear profiles.
基金Supported by Fund of Xiamen Municipal Science&Technology Commision(3502Z20092019)
文摘The effects of 6-benzylaminopurine （6-BA） on several physiological indexes of Caryota mitis and C. obtusa seedlings treated at varied temperatures were conducted, the leaves of the two palm species were sprayed with 0, 25, 50 and 100 mg · L1 6-BA solutions, the activities of superoxide dismutase （SOD）, peroxidase （POD）, and the contents of malondialdehyde （MDA）, proline, soluble protein, chlorophyll and chlorophyll a/b were determined under 25 ℃, 5 ℃ and 25 ℃ for 24 h, respectively. The dynamics of a series of important physiological components derived from the leaves were studied. It was indicated that all the above mentioned physiological indexes varied with different concentrations of 6-BA and temperature. The fuzzy comprehensive evaluation values for different concentrations of 6-BA at the recovery temperature 25℃ were 0.33, 0.28, 0.92 and 0.33, respectively for C. mitis, and 0.20, 0.49, 0.56 and 0.63, respectively for C. obtusa. It was concluded that leaves sprayed with different concentrations of 6-BA could affect the cold tolerance of palm seedlings. The optimal concentration of 6-BA was different for different palm species.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50872089 and 60577012)the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No. CityU 1194/07)
文摘We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.
文摘Combining real accelerating genetic algorithm(RAGA) with the optimization design of multi-hole and varied diameter pipe, the authors solved the problem of optimizing multi-dimensional parameters at the same time. In which the advanced convergence and easily to run into partial optimization were avoid. Applied the RAGA to solving the problem in the optimization design of fixed piping sprinkler irrigation system. The optimized parameters, such as diameters and the length of pipe were calculated and the result was reasonable, which provides as a reference to readers who work at related research.
基金Provincial Science and Technology Foundation of Guizhou
文摘In this paper, we give some sufficient conditions of the instability for the fourth order linear differential equation with varied coefficient, at least one of the characteristic roots of which has positive real part, by means of Liapunov's second method.
文摘The structure and function of protein are strongly pH-dependence. However, the inonization state of the protein varied with the pH value also depends on the local structure
文摘Finding clusters in data is a challenging problem especially when the clusters are being of widely varied shapes, sizes, and densities. Herein a new scalable clustering technique which addresses all these issues is proposed. In data mining, the purpose of data clustering is to identify useful patterns in the underlying dataset. Within the last several years, many clustering algorithms have been proposed in this area of research. Among all these proposed methods, density clustering methods are the most important due to their high ability to detect arbitrary shaped clusters. Moreover these methods often show good noise-handling capabilities, where clusters are defined as regions of typical densities separated by low or no density regions. In this paper, we aim at enhancing the well-known algorithm DBSCAN, to make it scalable and able to discover clusters from uneven datasets in which clusters are regions of homogenous densities. We achieved the scalability of the proposed algorithm by using the k-means algorithm to get initial partition of the dataset, applying the enhanced DBSCAN on each partition, and then using a merging process to get the actual natural number of clusters in the underlying dataset. This means the proposed algorithm consists of three stages. Experimental results using synthetic datasets show that the proposed clustering algorithm is faster and more scalable than the enhanced DBSCAN counterpart.
文摘Enrichment of copper to the culture mediumcould enhance the plant regeneration from cal-lus of indica rice variety Qiugui’ai 11. Westudied the effect of copper on plant regenera-tion of other rice varieties.Calli of 14 indica and 2 japonica varietieswere induced from disinfected mature embryoson an agar-gelled medium containing Nbasal
基金This work was supported by the National Natural Science Foundation of China under Grant(51879073).
文摘The zero-inertia model is widely used for simulating surface flow in irrigation systems.This model is accurate when inflow discharge is constant.However,simulation of irrigation systems with rapidly varied inflow discharge is needed due to the development of real time control irrigation technology.Hence,the objective of this study is to validate the zero-inertia model with rapidly varied inflow discharge.For this purpose,twenty-three border irrigation tests at a range of inflow changes on different field slopes and roughness coefficients were conducted.Then,the sensitivity analyses of bed slope,infiltration parameters,and roughness coefficient were examined.The results indicate that the zero-inertia model predictions are in good agreement with field data in both advance/recession times and flow depths.The infiltration parameters were the most sensitive input variable of the zero-inertia model.The input variables have a more considerable impact on the recession phase than the advance phase.
基金Project supported by the National Natural Science Foundation of China （No. 61175106）
文摘We tackle the problem of a biped running over varied and unknown terrain.Running is a necessary skill for a biped moving fast,but it increases the challenge of dynamic balance,especially when a biped is running on varied terrain without terrain information(due to the difficulty and cost of obtaining the terrain information in a timely manner).To address this issue,a new dynamic indicator called the sustainable running criterion is developed.The main idea is to sustain a running motion without falling by maintaining the system states within a running-feasible set,instead of running on a periodic limit cycle gait in the traditional way.To meet the precondition of the criterion,the angular moment about the center of gravity(COG) is restrained close to zero at the end of the stance phase.Then to ensure a small state jump at touchdown on the unknown terrain,the velocity of the swing foot is restrained within a specific range at the end of the flight phase.Finally,the position and velocity of the COG are driven into the running-feasible set.A five-link biped with underactuated point foot is considered in simulations.It is able to run over upward and downward terrain with a height difference of 0.15 m,which shows the effectiveness of our control scheme.
基金The authors gratefully acknowledge the financial support provided by the National Key R&D Program of China(No.2020YFF0426370)the National Natural Science Foundation of China(Grant No.51978040).
文摘The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process.To analyze the rotation state,cutting performance,and adaptability of disc cutters during shield tunneling in soft–hard varied strata,the Holmquist Johnson Cook and Federal Highway Administration constitutive models are introduced to numerically simulate the failure process of materials on the excavation face and to calculate the load of disc cutters.Additionally,the parameters of the models are modified based on laboratory disc cutter excavation test results.The results of numerical calculation can reflect the load level and the behavior of the disc cutters during operation.The tangential loads of the disc cutters during the cutting of four typical soft-strata excavation face models are numerically calculated,thus providing reference values for the starting torque of the disc cutters.A greater penetration is suggested for soft-strata tunneling to allow the disc cutters to rotate smoothly and continuously as well as to guarantee a better cutting effect.The disc cutters in the center of the cutterhead should be specified with a lower starting torque to prevent uneven wear,rotation stagnation,cutterhead clogging,and other adverse phenomena.
基金Project supported by the Science Fund of the Chinese Academy of Sciences for Young Scientists.
文摘Let D be a digital manifold, J the subset of non-empty of D; and let A<sub>1</sub>, A<sub>2</sub>, …, A<sub>m</sub> be m real numbers with A<sub>1</sub>【A<sub>2</sub>【…【A<sub>m</sub>. Supposing function f<sub>J</sub>: J → A<sub>1</sub>,…, A<sub>m</sub>, we want to find a function f<sub>D</sub>: D→{A<sub>1</sub>…, A<sub>m</sub>}, such that f<sub>D</sub> is gradual variation on D, having f<sub>D</sub>（x）=f<sub>J</sub>（x）, x∈J. Such f<sub>D</sub> is called the gradually varied extension or interpolation of f<sub>J</sub>.
基金Project supported by the Science Fund of the Chinese Academy of Sciences for Young Scientists
文摘Filling is an important part in pattern recognition and computer vision. In the discrete plane （grid of plane）∑<sub>2</sub>, fill means 'determination of the region D enclosed by the simple closed curve J which is given beforehand'. In other words, if the valuation of the point on the contour J is 1, we want to do a valuation for ∑<sub>2</sub> to make the valuation of the point p be 1 iff point p belongs to D.
