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Distribution and Length-weight Relationships of Glyptosternoid Fishes in the Drung River Basin, Yunnan 被引量:6
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作者 孔德平 潘晓赋 +1 位作者 杨君兴 陈自明 《Zoological Research》 CAS CSCD 北大核心 2005年第6期632-637,共6页
Glyptosternoid fishes are a group of sisorid catfishes living in torrents of rivers mainly originating from the Qinghai-Tibet Plateau. Based on our survey in the Drung River Basin, seven collecting sites were investig... Glyptosternoid fishes are a group of sisorid catfishes living in torrents of rivers mainly originating from the Qinghai-Tibet Plateau. Based on our survey in the Drung River Basin, seven collecting sites were investigated and 271 glyptosternoid fishes caught belong to three species (Pareuchiloglanis kamengensis, Exostoma labiatum and Oreoglanis mocropterus). Features of the distribution of the three catfishes were assessed. More individuals of E. labiatum were caught in the lower reaches of the Drung River with fast water velocity and it might be more adapted to a torrent habitat. The relationships between standard length (L) and weight (W) for P. kamengensis, E. labiatum and O. macropterus were also studied, and the parameter b of the L-W relationship (W = aL^b) ranged between 2. 8201 and 3. 0131. From the present study, all the three catfish species grow allometrically and the growth type of E. labiatum is the closest to a symmetrical one. 展开更多
关键词 CATFISH Drung River Basin distribution feature length WEIGHT
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THE QUEUE-LENGTH DISTRIBUTION FOR M^x/G/1 QUEUE WITH SINGLE SERVER VACATION 被引量:2
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作者 唐应辉 唐小我 《Acta Mathematica Scientia》 SCIE CSCD 2000年第3期397-408,共12页
This paper studies the bulk-arrival M-x/G/1 queue with single server vacation. By introducing the server busy period and using the Laplace transform, the recursion expression of the Laplace transform of the transient ... This paper studies the bulk-arrival M-x/G/1 queue with single server vacation. By introducing the server busy period and using the Laplace transform, the recursion expression of the Laplace transform of the transient queue-length distribution is derived. Furthermore, the distribution and stochastic decomposition result of the queue length at a random point in equilibrium are obtained. Especially some results for the single-arrival M/G/1 queue with single server vacation and bulk-arrival M-x/G/1 queue but with no server vacation can be derived directly by the results obtained in this paper. 展开更多
关键词 server vacation queue length transient distribution equilibrium distribution stochastic decomposition
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Cryogenic Liquid Slug and Taylor Bubble Length Distributions in an Inclined Tube 被引量:2
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作者 王淑华 张华 王经 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2009年第1期20-26,共7页
An experimental study was carried out to understand the phenomena of the boiling flow of liquid nitrogen in an inclined tube with closed bottom by using a high speed motion analyzer. The experimental tube is 0.018 m I... An experimental study was carried out to understand the phenomena of the boiling flow of liquid nitrogen in an inclined tube with closed bottom by using a high speed motion analyzer. The experimental tube is 0.018 m ID and 1.0m in length. The range of the inclination angle is 45°-9° from the horizontal. The experiment focused on the effect of the inclination angle show that the mean liquid slug length and Taylor bubble length increase with the increasing xlD at various inclination angles. At the same x/D, the mean liquid slug length and Taylor bubble length increase first, and then decrease with decreasing inclination angles, with the maximum at 60°. In the vertical tube, standard deviation of the nitrogen Taylor bubble iength increase with the increasing xlD. For the inclined tube, standard deviation of the nitrogen Taylor bubble length increases first, and then decreases with the increasing x/D. Standard deviation of the liquid slug length increases with increasing x/D for all inclination angles. 展开更多
关键词 NITROGEN BOILING Taylor bubble liquid slug length distribution inclined tube
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Root length density distribution and associated soil water dynamics for tomato plants under furrow irrigation in a solar greenhouse 被引量:3
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作者 QIU Rangjian DU Taisheng KANG Shaozhong 《Journal of Arid Land》 SCIE CSCD 2017年第5期637-650,共14页
Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in wat... Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in water-limited regions. The objectives of this study are to analyze root length density distribution and to explore soil water dynamics by simulating soil water content using a HYDRUS-2D model with consideration of root water uptake for furrow irrigated tomato plants in a solar greenhouse in Northwest China. Soil water contents were also in-situ observed by the ECH_2O sensors from 4 June to 19 June and from 21 June to 4 July, 2012. Results showed that the root length density of tomato plants was concentrated in the 0–50 cm soil layers, and radiated 0–18 cm toward the furrow and 0–30 cm along the bed axis. Soil water content values simulated by the HYDRUS-2D model agreed well with those observed by the ECH_2O sensors, with regression coefficient of 0.988, coefficient of determination of 0.89, and index of agreement of 0.97. The HYDRUS-2D model with the calibrated parameters was then applied to explore the optimal irrigation scheduling. Infrequent irrigation with a large amount of water for each irrigation event could result in 10%–18% of the irrigation water losses. Thus we recommend high irrigation frequency with a low amount of water for each irrigation event in greenhouses for arid region. The maximum high irrigation amount and the suitable irrigation interval required to avoid plant water stress and drainage water were 34 mm and 6 days, respectively, for given daily average transpiration rate of 4.0 mm/d. To sum up, the HYDRUS-2D model with consideration of root water uptake can be used to improve irrigation scheduling for furrow irrigated tomato plants in greenhouses in arid regions. 展开更多
关键词 root length density distribution HYDRUS-2D model soil water content irrigation scheduling greenhouse
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Fast implementation of length-adaptive privacy amplification in quantum key distribution 被引量:6
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作者 张春梅 李默 +8 位作者 黄靖正 Patcharapong Treeviriyanupab 李宏伟 李芳毅 王川 银振强 陈巍 Keattisak Sripimanwat 韩正甫 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第9期112-117,共6页
Post-processing is indispensable in quantum key distribution (QKD), which is aimed at sharing secret keys between two distant parties. It mainly consists of key reconciliation and privacy amplification, which is use... Post-processing is indispensable in quantum key distribution (QKD), which is aimed at sharing secret keys between two distant parties. It mainly consists of key reconciliation and privacy amplification, which is used for sharing the same keys and for distilling unconditional secret keys. In this paper, we focus on speeding up the privacy amplification process by choosing a simple multiplicative universal class of hash functions. By constructing an optimal multiplication algorithm based on four basic multiplication algorithms, we give a fast software implementation of length-adaptive privacy amplification. "Length-adaptive" indicates that the implementation of privacy amplification automatically adapts to different lengths of input blocks. When the lengths of the input blocks are 1 Mbit and 10 Mbit, the speed of privacy amplification can be as fast as 14.86 Mbps and 10.88 Mbps, respectively. Thus, it is practical for GHz or even higher repetition frequency QKD systems. 展开更多
关键词 length-adaptive privacy amplification multiplication algorithms quantum key distribution
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AN APPROACH TO THEORETICAL FUNCTION OF DISLOCATION LINK LENGTH DISTRIBUTION IN METAL
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作者 WANG Bosheng SUN Fuyu MENG Qing’ en XU Wenchong Central Iron and steel Research Institute,Ministry of Metallurgical Industry,Beijing,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1992年第5期314-317,共4页
A statistical distribution function of the dislocation link length,in unit volume of the crystalline materials has been derived theoretically after semi-infinite normalization by as- suming the distribution of actual ... A statistical distribution function of the dislocation link length,in unit volume of the crystalline materials has been derived theoretically after semi-infinite normalization by as- suming the distribution of actual links in all positions of crystalline materials with equal prob- ability,i.e. (l)dl=2ρl_γ^(-4)l^2exp(l^2/l_γ~2)dl where ρ is dislocation density,This assumption seems to be reasonable for polycrystalline fec metallic materials,and confirmation has been found in pure Ni and stainless steel 1Cr18Ni9Ti TEM experiments alresults. 展开更多
关键词 dislocation link length distribution function crystal defect
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Differences in Starch Chain Length Distribution and Structure Characteristics of Early-Indica Rice Under Different Temperature Treatments During Grain-Filling
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作者 ZHONGLian-jin CHENGFang-min +1 位作者 ZHANGGuo-ping SUNZong-xiu 《Agricultural Sciences in China》 CAS CSCD 2005年第1期21-25,共5页
Effects of temperature during grain-filling on chain length distribution and structure characteristics of 4 early-seasonindica rice cultivars were investigated under the environment-controlled conditions. The plants a... Effects of temperature during grain-filling on chain length distribution and structure characteristics of 4 early-seasonindica rice cultivars were investigated under the environment-controlled conditions. The plants at flowering stage weresubjected to two temperature treatments until maturity (the mean dairy air temperature, 22 and 32C for optimum temperaturetreatment and high temperature treatment, respectively). The result showed that high temperature during grain-fillingsignificantly decreased the long B-chain content and increased the intermediate B-chain content. But the effect of hightemperature on other starch chains appeared to be cultivar-dependant. The crystalline characteristics of rice starch werealso affected by temperature during grain-filling. The intensity at 18 2q of X-ray diffraction pattern of rice samples underhigh temperature was higher than those under optimum temperature, though all rice starches performed A-crystallinetype. Moreover, the intensity at 18 2q was positive correlation with intermediate B-chain content and negative correlationwith long B-chain content. 展开更多
关键词 Rice (Oryza sativa L.) Temperature STARCH Chain length distribution Crystalline structure
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Passive decoy-state quantum key distribution for the weak coherent photon source with finite-length key 被引量:1
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作者 李源 鲍皖苏 +2 位作者 李宏伟 周淳 汪洋 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第1期452-459,共8页
Passive decoy-state quantum key distribution systems, proven to be more desirable than active ones in some scenarios, also have the problem of device imperfections like finite-length keys. In this paper, based on the ... Passive decoy-state quantum key distribution systems, proven to be more desirable than active ones in some scenarios, also have the problem of device imperfections like finite-length keys. In this paper, based on the WCP source which can be used for the passive decoy-state method, we obtain the expressions of single-photon error rates, single-photon counts, and phase error rates. According to the information of smooth min-entropy, we calculate the key generation rate under the condition of finite-length key. Key generation rates with different numbers of pulses are compared by numerical simulations. From the results, it can be seen that the passive decoy-state method can have good results if the total number of pulses reaches 1010. We also simulate the passive decoy-state method with different probabilities of choosing a pulse for parameter estimation when the number of pulses is fixed. 展开更多
关键词 quantum key distribution passive decoy-state finite-length key weak coherent pulses
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Experimental study on upward bubble velocity and pierce length distributions in a water model of copper converter
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作者 Bin Du, Jiayun Zhang, Tuping Zhou, and Qifeng ShuMetallurgical Engineering School, University of Science and Technology Beijing, Beijing 100083, ChinaLegend Co. Ltd., Beijing 100085, China 《Journal of University of Science and Technology Beijing》 CSCD 2003年第6期16-21,共6页
The upward bubble velocity and the pierce length distributions in a sectionalwater model of the copper converter in Guixi Smelter in Jiangxi, China, were measured using atwo-contact electro-resistivity probe. In the c... The upward bubble velocity and the pierce length distributions in a sectionalwater model of the copper converter in Guixi Smelter in Jiangxi, China, were measured using atwo-contact electro-resistivity probe. In the case of using a single tuyere, the bubble velocitydistribution along longitudinal direction was similar to that derived from Guassian function. Beyondthe center of the longitudinal range, the bubble pierce length exhibited a sudden increase. Theupward bubble velocity at a specified location could go up to meters per second. Its probability ata fixed location obeys a lognormal function; the bubble pierce length there varies bellow a fewcentimeters. In the case of using multi-tuyeres, the upward bubble velocity was roughly uniformright above the tuyeres and showed a slow decrease beyond this region. The bubble pierce lengthwithin both of these two regions was roughly uniform. Its average value in the former region,however, was found to he somewhat lower than that in the later. 展开更多
关键词 upward bubble velocity bubble pierce length distribution copper converter
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Velocity distribution of flow with submerged flexible vegetations based on mixing-length approach 被引量:2
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作者 槐文信 韩杰 +3 位作者 曾玉红 安翔 钱忠东 Yu-lu LIU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第3期343-351,共9页
By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter (micro ADV) was used to measure local flow... By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter (micro ADV) was used to measure local flow velocities and Reynolds stress. The results show that hydraulic characteristics in non-vegetation and vegetation layers are totally different. In a region above the vegetation, Reynolds stress distribution is linear, and the measured velocity profile is a classical logarithmic one. Based on the concept of new-riverbed, the river compression parameter representing the impact of vegetation on river is given, and a new assumption of mixing length expression is made. The formula for time-averaged velocity derived from the expression requires less parameters and simple calculation, and is useful in applications. 展开更多
关键词 flexible vegetation PVC slice micro ADV mixing-length approach streamwise velocity distribution Reynolds stress river compression parameter
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Effect of Lithium Chloride on the Fibre Length Distribution, Processing Temperature and the Rheological Properties of High-Yield-Pulp-Fibre-Reinforced Modified Bio-Based Polyamide 11 Composite
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作者 Robenson Cherizol Mohini Sain Jimi Tjong 《Advances in Nanoparticles》 2017年第2期48-61,共14页
The aim of this work was to investigate the effect of lithium chloride (LiCl) on the fibre length distribution, melting temperature and the rheological characteristics of high yield pulp fibre reinforced polyamide bio... The aim of this work was to investigate the effect of lithium chloride (LiCl) on the fibre length distribution, melting temperature and the rheological characteristics of high yield pulp fibre reinforced polyamide biocomposite. The inorganic salt lithium chloride (LiCl) was used to decrease the melting and processing temperature of bio-based polyamide 11. The extrusion method and Brabender mixer approaches were used to carry out the compounding process. The densities and fibre content were found to be increased after processing using both compounding methods. The HYP fibre length distribution analysis realized using the FQA equipment showed an important fibre-length reduction after processing by both techniques. The rheological properties of HYP-reinforced net and modified bio-based polyamide 11 “PA11” (HYP/PA11) composite were investigated using a capillary rheometer. The rheological tests were performed in function of the shear rate for different temperature conditions. The low-temperature process compounding had higher shear viscosity;this was because during the process the temperature was low and the mixing and melting were induced by the high shear rate created during compounding process. Experimental test results using the extrusion process showed a steep decrease in shear viscosity with increasing shear rate, and this melt-flow characteristic corresponds to shear-thinning behavior in HYP/PA11, and this steep decrease in the melt viscosity can be associated to the hydrolyse reaction of nylon for high pulp fibre moisture content at high temperature. In addition to the low processing temperature, the melt viscosity of the biocomposite using the Brabender mixer approach increases with increasing shear rate, and this stability in the increase even at high shear rate for high pulp moisture content is associated to the presence of inorganic salt lithium chloride which creates the hydrogen bonds with pulp during the compounding process. 展开更多
关键词 HYP/PA11 Melting Temperature of NYLON 11 Inorganic Salt Chloride Lithium (Licl) Fibre Aspect Ratio and length distribution RHEOLOGICAL Characteristic
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Inverse Length Biased Maxwell Distribution:Statistical Inference with an Application
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作者 Amer Ibrahim Al-Omari Ayed R.A.Alanzi 《Computer Systems Science & Engineering》 SCIE EI 2021年第10期147-164,共18页
In this paper,we suggested and studied the inverse length biased Maxell distribution(ILBMD)as a new continuous distribution of one parameter.The ILBMD is obtained by considering the inverse transformation technique of... In this paper,we suggested and studied the inverse length biased Maxell distribution(ILBMD)as a new continuous distribution of one parameter.The ILBMD is obtained by considering the inverse transformation technique of the Maxwell length biased distribution.Statistical characteristics of the ILBMD such as the moments,moment generating function,mode,quantile function,the coefficient of variation,coefficient of skewness,Moors and Bowley measures of kurtosis and skewness,stochastic ordering,stress-strength reliability,and mean deviations are obtained.In addition,the Bonferroni and Lorenz curves,Gini index,the reliability function,the hazard rate function,the reverse hazard rate function,the odds function,and the distributions of order statistics for the ILBMD,are presented.The ILBMD parameter is estimated using the maximum likelihood method,the method of moments,the maximum product of spacing technique,the ordinary and weight least square procedures,and the Cramer-Von-Mises methods.The Fishers information,as well as the Rényi and q-entropies,are derived.To investigate the usefulness of the proposed lifetime distribution and to illustrate the purpose of the study,a real dataset of the relief times of 20 patients receiving an analgesic is used. 展开更多
关键词 Maxell distribution inverse length biased Maxwell distribution Fisher’s information methods of estimation goodness of fit tests
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Stability, variation, and application of AFIS fiber length distributions
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作者 HINDS Zachary KELLY Brendan Robert HEQUET Eric Francois 《Journal of Cotton Research》 2020年第2期79-89,共11页
Background:Fiber length is one of the primary quality parameters for the cotton industry when considering the textile performance and end-use quality of cotton.Currently,many decisions regarding cotton fiber length ut... Background:Fiber length is one of the primary quality parameters for the cotton industry when considering the textile performance and end-use quality of cotton.Currently,many decisions regarding cotton fiber length utilize the industry standard measurement device,i.e.,the High Volume Instrument(HVI).However,it is documented that complete fiber length distributions hold more information than the currently reported HVI length parameters,i.e.,upper half mean length(UHML)and uniformity index(UI).An alternative measurement device,the Advanced Fiber Information System(AFIS),is able to capture additional information about fiber length distribution.What is currently not known is how much additional information the AFIS length distribution holds.Results:The stability of differences in within-sample variation in fiber length captured by the AFIS length distribution by number characterizing differences between samples was deemed stable across the extended testing period.A diverse breeding population was evaluated and four significant sources of within sample variation in length were identified.A comparison of the ability between HVI length parameters and AFIS fiber length distribution to correctly categorize breeding lines to their family was performed.In all cases,the AFIS fiber length distribution more accurately identified germplasm families.Conclusions:The long-term stability test of the AFIS fiber length distribution by number shows that the measurement is stable and can be used to assess differences across samples.However,more information about within-sample variation in fiber length than that can be captured by length parameters is needed to assess differences across samples in many applications.Four length parameters outperform two length parameters when trying to identify the familial background of the samples in this set.These parameters characterize distributional shape differences that are not captured by the standard AFIS length parameters,UQL and short fiber content by number(SFCn).These findings suggest that additional types of variation in cotton fiber length are not captured and are therefore not currently used in most cotton breeding programs. 展开更多
关键词 COTTON Fiber quality Fiber length distribution Advanced Fiber information system(AFIS)
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Probability Distribution of Average Length of Node Path and Its Evolution Trace of Aviation Network of China Based on Complex Network
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作者 Cheng Xiangjun Yang Fang Li Tao 《Journal of Traffic and Transportation Engineering》 2021年第2期41-52,共12页
In order to reveal the complex network feature and its evolution principle of aviation network of China,probability distribution and its evolution trace of average length of node path of aviation network of China were... In order to reveal the complex network feature and its evolution principle of aviation network of China,probability distribution and its evolution trace of average length of node path of aviation network of China were researched according to statistics data in years 1988,1994,2001,2008 and 2015 of civil aviation of China.Floyd algorithm to calculate the path length between any two nodes of network was applied and average length of node path of aviation network was obtained according to this algorithm.It was discovered that average length of node path to other nodes had normal distribution function in each year.At meantime,the location parameter and scale parameter of normal distribution function had linear evolution trace.Airline rate was an index to describe the density of airline.It was found that average length of node path of aviation network of China evolved synchronously with airline rate and they had linear relationship. 展开更多
关键词 Aviation network of China average length of node path probability distribution evolution trace airline rate
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Effect of nano-particle size on product distribution and kinetic parameters of Fe/Cu/La catalyst in Fischer-Tropsch synthesis 被引量:4
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作者 Ali Nakhaei Pour Mohammad Reza Housaindokht +1 位作者 Sayyed Faramarz Tayyari Jamshid Zarkesh 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2010年第2期107-116,共10页
Effects of nano-particle size on hydrocarbon production rates and distributions for precipitated Fe/Cu/La catalysts in Fischer-Tropsch synthesis were investigated.Nano-structured iron catalyst was prepared by micro-em... Effects of nano-particle size on hydrocarbon production rates and distributions for precipitated Fe/Cu/La catalysts in Fischer-Tropsch synthesis were investigated.Nano-structured iron catalyst was prepared by micro-emulsion method.The concept of two superimposed AndersonSchulz-Flory (ASF) distributions has been applied for the representation of the effects of reaction conditions and nano-particles size on kinetics parameters and product distributions.These results reveal that by reducing the particle size of catalyst,the break in ASF distributions was decreased.Also useful different kinetics equations for synthesis of C3 to C9 and C10 to C22 were determined by using α1 and α2 chain growth probabilities. 展开更多
关键词 chain length distribution Fischer-Tropsch synthesis iron-based catalyst nano-particle size
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Application of Maximum Entropy Distribution to the Statistical Properties of Wave Groups 被引量:2
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作者 于定勇 李晶 刘华兴 《China Ocean Engineering》 SCIE EI 2007年第3期461-470,共10页
The new distributions of the statistics of wave groups based on the maximum entropy principle are presented. The maximum entropy distributions appear to be superior to conventional distributions when applied to a limi... The new distributions of the statistics of wave groups based on the maximum entropy principle are presented. The maximum entropy distributions appear to be superior to conventional distributions when applied to a limited amount of information. Its applications to the wave group properties show the effectiveness of the maximum entropy distribution. FFF filtering method is employed to obtain the wave envelope fast and efficiently. Comparisons of both the maximum entropy distribution and the distribution of Longuet-Higgins (1984) with the laboratory wind-wave data show that the former gives a better fit. 展开更多
关键词 maximum entropy distribution high run length wave group length probability density function wave envelope
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Vertical Distribution of Momentum Exchange Coefficient and Sediment Concentration in Estuarine and Coastal Waters 被引量:2
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作者 黄惠明 王义刚 +1 位作者 闻云呈 祝慧敏 《China Ocean Engineering》 SCIE EI 2010年第4期677-692,共16页
Vertical structures of momentum exchange coefficient and sediment concentration are the keys in the research on es- tuarine and coastal suspended sediment transport. Based on the parabolic mixing length distribution p... Vertical structures of momentum exchange coefficient and sediment concentration are the keys in the research on es- tuarine and coastal suspended sediment transport. Based on the parabolic mixing length distribution pattern, the distribu- tion pattern of vertical momentum exchange coefficient which is suitable for estuarine and coastal waters is constructed. A compari^n with steady flow and measured momentum exchange coefficient during one tidal cycle in the Menai Strait of England shows that the result of this pattern is closer to the measured values than those of commonly used Rouse' s and van Rijn's patterns, and the pattern is also suitable for estuarine and coastal waters. Successively, based on the precon- dition that momentum exchange coefficient is equivalent to sediment turbulent diffusion coefficient, and combining with the Diffusion Theory, we obtain the exponential vertical distribution pattern of sediment concentration, which is also suitable for estuafine and coastal waters, Thereby, using measured vertical stratified sediment concentration data of the South and the North Passages of the Yangtze Estuary and Zhoushan archipelago waters for fitting calculation, and comparing the results with those from Rouse's (1938) and Zhang et al. 's (1989) formulas, the results show that the exponential vertical distribution pattern of sediment concentration obtained in the present study not only overcomes the defect of Rouse's formula that the surface sediment concentration will be 0, but also has a holistic higher precision along the vertical lines than those of Rouse's and Zhang et al. 's formulas. 展开更多
关键词 estuary and coast parabolic mixing length vertical distribution momentum exchange coefficient sedimentconcentration
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Analytical solution of velocity distribution for flow through submerged large deflection flexible vegetation 被引量:2
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作者 Wei-jie WANG Wen-xin HUAI +1 位作者 Yu-hong ZENG Ji-fu ZHOU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2015年第1期107-120,共14页
An analytical solution for predicting the vertical distribution of streamwise mean velocity in an open channel flow with submerged flexible vegetation is proposed when large bending occurs. The flow regime is separate... An analytical solution for predicting the vertical distribution of streamwise mean velocity in an open channel flow with submerged flexible vegetation is proposed when large bending occurs. The flow regime is separated into two horizontal layers: a vegetation layer and a free water layer. In the vegetation layer, a mechanical analysis for the flexible vegetation is conducted, and an approximately linear relationship between the drag force of bending vegetation and the streamwise mean flow velocity is observed in the case of large deflection, which differes significantly from the case of rigid upright vegetation. Based on the theoretical analysis, a linear streamwise drag force-mean flow velocity expression in the momentum equation is derived, and an analytical solution is obtained. For the free water layer, a new expression is presented, replacing the traditional logarithmic velocity distribution, to obtain a zero velocity gradient at the water surface. Finally, the analytical predictions are compared with published experimental data, and the good agreement demonstrates that this model is effective for the open channel flow through the large deflection flexible vegetation. 展开更多
关键词 analytical velocity distribution linear drag force flexible vegetation largedeflection mixing length theory
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Studies on product distribution of alkali promoted iron catalyst in Fischer-Tropsch synthesis 被引量:2
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作者 Ali Nakhaei Pour Masoud Zare Yahya Zamani 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2010年第1期31-34,共4页
The dependencies of hydrocarbon product distributions of alkali promoted iron catalyst in Fischer-Tropsch synthesis have been studied. The concept of two superimposed Anderson-Schulz-Flory distributions has been appli... The dependencies of hydrocarbon product distributions of alkali promoted iron catalyst in Fischer-Tropsch synthesis have been studied. The concept of two superimposed Anderson-Schulz-Flory distributions has been applied for the representation of the effects of Mg, La and Ca promoters on product distributions. The FTS performance of the catalysts was tested in a fixed bed reactor under the conditions 563 K, 1.7 MPa, H2/CO = 1 and space velocities 4.86 and 13.28 nl·h^-1·gFe^-1. The results indicate that appropriate amounts of these promoters enhance the break in ASF distributions in the order Ca 〉 Mg 〉 La because of the rising of the catalyst surface basicity. 展开更多
关键词 chain length distribution Fischer-Tropsch synthesis Fe catalyst
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Soil nutrients in relation to vertical roots distribution in the riparian zone of Three Gorges Reservoir,China 被引量:3
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作者 ZHONG Rong-hua HU Jin-ming +2 位作者 BAO Yu-hai Wang Fei HE Xiu-bin 《Journal of Mountain Science》 SCIE CSCD 2018年第7期1498-1509,共12页
Since the impoundment of the Three Gorges Reservoir(TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts o... Since the impoundment of the Three Gorges Reservoir(TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts on soil nutrients in the water level fluctuation zone of TGR. Roots of four predominant herbaceous plants in the study area, specifically, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, and their corresponding relation with soil nutrient contents were investigated. Root surface area density was determined with Win RHIZO, and the relationships of root distribution with soil depths and soil nutrient contents were studied. The results indicates that most roots are distributed in the top soil layer of 0-10 cm. Estimated root surface area density for the selected grass species ranges from 0.16 to 13.44 cm^2/cm^3, and decreases exponentially with an increase in soil depth. Soil organic matter and total nitrogen contents are significantly lower on bare control area than the corresponding values on the grasslands. Total nutrient contents on grasslands of C. dactylon and H. compressa are higher than those of other grass areas. Root length density and root surface area density are significantly correlated with soil organic matter and total nitrogen content for the four grasslands. The present results suggests that plant roots have significant effects on the distribution of soil nutrients in soil profiles in the riparian zone along the TGR. Nevertheless, additional investigations are needed to reveal the specific interactions between plant roots distribution, soil nutrients and water level fluctuations. 展开更多
关键词 Roots distribution Soil nutrients Water level fluctuations Riparian zone Root surface area density Root length density
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