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Numerical investigation of the concentric annulus flow around a cylindrical body with contrasted effecting factors 被引量:7
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作者 张雪兰 孙西欢 +3 位作者 李永业 郗夏楠 郭飞 郑利剑 《Journal of Hydrodynamics》 SCIE EI CSCD 2015年第2期273-285,共13页
This paper studies the wall-bounded flow around a cylindrical at a high Reynolds numbers body in a determined computational domain, with simulations of the 3-D, turbulent concentric annulus flow in a straight pipe. Nu... This paper studies the wall-bounded flow around a cylindrical at a high Reynolds numbers body in a determined computational domain, with simulations of the 3-D, turbulent concentric annulus flow in a straight pipe. Numerical results show that a reversing zone, appearing as a tongue zone with nested velocities higher than the surrounding area, exists behind the cylindrical body. The annulus space is a region of high velocity and low pressure. The zero velocity, of combined the X- velocity and the Y- velocity, exists in the cross sections and no vortex shedding is formed behind the attaching cylinders. Among all investigated effecting factors, the diameters of the attaching and the main cylinders affect the wake feature behind the cylindrical body while the main cylinder length does not affect the distribution tendency of the flow field. The diameters of the main cylinder and the pipe affect the pressure values and the distribution tendencies on the main cylinder surface. Obviously, the increase of the pipe diameter reduces the drag coefficient of the cylindrical body and the increase of the diameter of the main cylinder increases the drag coefficient greatly. The numerical investigation of the concentric annulus flow provides foundations for further improvements of the intricate flow studies. 展开更多
关键词 numerical investigation concentric annulus turbulent flow contrasted effecting factors hydraulic characteristics
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Experimental Study and Fragility Analysis of Effective-Length Factors in Column Buckling
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作者 Brannan Shepherd Tadeh Zirakian 《Journal of Building Material Science》 2023年第1期9-16,共8页
The design of columns relies heavily on the basis of Leonhard Euler’s Theory of Elastic Buckling.However,to increase the accuracy in determining the maximum critical load a column can withstand before buckling,a cons... The design of columns relies heavily on the basis of Leonhard Euler’s Theory of Elastic Buckling.However,to increase the accuracy in determining the maximum critical load a column can withstand before buckling,a constant was introduced.This dimensionless coefficient is K,also known as the effective-length factor.This constant is often found in building design codes and varies in value depending on the type of column support that is applied.This paper presents experimental and analytical studies on the determination of the effective-length factor in the buckling stability of columns with partially-fixed support conditions.To this end,the accurate K value of the columns tested by the Instron Testing Machine(ITM)at California State University,Northridge’s(CSUN’s)Mechanics Laboratory is determined.The ITM is used in studying the buckling of columns where the supports are neither pinned nor fixed,and the material cross-section rather rests upon the machine while loading is applied axially.Several column specimens were tested and the experimental data were analyzed in order to estimation of the accurate effective-length factor.The calculations from the tested results as well as the conducted probabilistic analysis shed light on how a fragility curve may aid in predicting the effective-length value of future tests. 展开更多
关键词 Column buckling Fragility curve Critical loading Effective length factor Fixity
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Predictive active control of building structures using LQR and artificial intelligence
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作者 Nirmal S.Mehta Vishisht Bhaiya +1 位作者 K.A.Patel Ehsan Noroozinejad Farsangi 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第2期489-502,共14页
This study presents a neural network-based model for predicting linear quadratic regulator(LQR)weighting matrices for achieving a target response reduction.Based on the expected weighting matrices,the LQR algorithm is... This study presents a neural network-based model for predicting linear quadratic regulator(LQR)weighting matrices for achieving a target response reduction.Based on the expected weighting matrices,the LQR algorithm is used to determine the various responses of the structure.The responses are determined by numerically analyzing the governing equation of motion using the state-space approach.For training a neural network,four input parameters are considered:the time history of the ground motion,the percentage reduction in lateral displacement,lateral velocity,and lateral acceleration,Output parameters are LQR weighting matrices.To study the effectiveness of an LQR-based neural network(LQRNN),the actual percentage reduction in the responses obtained from using LQRNN is compared with the target percentage reductions.Furthermore,to investigate the efficacy of an active control system using LQRNN,the controlled responses of a system are compared to the corresponding uncontrolled responses.The trained neural network effectively predicts weighting parameters that can provide a percentage reduction in displacement,velocity,and acceleration close to the target percentage reduction.Based on the simulation study,it can be concluded that significant response reductions are observed in the active-controlled system using LQRNN.Moreover,the LQRNN algorithm can replace conventional LQR control with the use of an active control system. 展开更多
关键词 active control system linear quadratic regulator artificial neural networks state-space approach response effectiveness factor RESILIENCE
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Effects of main range and strength factors on change of COD in a shallow lake 被引量:2
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作者 Fan Cheng xin Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1998年第1期51-57,共7页
A model involving the relationship between non conservative matter (COD) and main range factors(loading, water stage) and strength factor (temperature) in a shallow lake has been established on the basis of less chan... A model involving the relationship between non conservative matter (COD) and main range factors(loading, water stage) and strength factor (temperature) in a shallow lake has been established on the basis of less change of water stage area curve in certain extent, broader distribution in pollution sources and more homogeneous in quantity of heat. The effects of COD inflow and /or outflow, and hydro meterological factors upon COD content in Lake Taihu were calculated and simulated under the actual situation of the loadings and regimen. The results simulated by using the model are in better agreement with the observed field data. The error of the model was also discussed. 展开更多
关键词 COD model environmental factor effects shallow lake.
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Analysis of effect factors-based stochastic network planning model 被引量:1
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作者 Chu Chunchao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第1期112-118,共7页
Looking at all the indeterminate factors as a whole and regarding activity durations as independent random variables, the traditional stochastic network planning models ignore the inevitable relationship and dependenc... Looking at all the indeterminate factors as a whole and regarding activity durations as independent random variables, the traditional stochastic network planning models ignore the inevitable relationship and dependence among activity durations when more than one activity is possibly affected by the same indeterminate factors. On this basis of analysis of indeterminate effect factors of durations, the effect factors-based stochastic network planning (EFBSNP) model is proposed, which emphasizes on the effects of not only logistic and organizational relationships, but also the dependent relationships, due to indeterminate factors among activity durations on the project period. By virtue of indeterminate factor analysis the model extracts and describes the quantitatively indeterminate effect factors, and then takes into account the indeterminate factors effect schedule by using the Monte Carlo simulation technique. The method is flexible enough to deal with effect factors and is coincident with practice. A software has been developed to simplify the model-based calculation, in VisualStudio.NET language. Finally, a case study is included to demonstrate the applicability of the proposed model and comparison is made with some advantages over the existing models. 展开更多
关键词 stochastic network planning ACTIVITY DURATION effect factor
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Analysis on the temporal-spatial distribution character and effect factors of PM10 in the hinterland of Taklimakan Desert and surrounding area 被引量:1
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作者 Ali Mamtimin 《Research in Cold and Arid Regions》 2011年第6期526-534,共9页
In recent years, the physical and chemical properties of dust aerosols from the dust source area in northem China have attracted increased attention. In this paper, Thermo RP 1400a was used for online continuous obser... In recent years, the physical and chemical properties of dust aerosols from the dust source area in northem China have attracted increased attention. In this paper, Thermo RP 1400a was used for online continuous observation and study of the hinterland of Taldimakan, Tazhong, and surrounding areas of Kurnul and Hotan from 2004 to 2006. In combination with weather analysis during a sandstorm in the Tazhong area, basic characteristics and influencing factors of dust aerosol PMl0 have been summarized as below: (1) The occurrence days of floating dust and blowing dust appeared with an increasing trend in Kumul, Tazhong and Hotan, while the number of dust storm days did not significantly change. The frequency and intensity of dust weather were major factors affecting the concentration of dust aerosol PMI0 in the desert. (2) The mass concentration of PM10 had significant regional distribution characteris- tics, and the mass concentration at the eastern edge of Taklimakan, Kumul, was the lowest; second was the southern edge of the desert, Hotan; and the highest was in the hinterland of the desert, Tazhong. (3) High values of PM10 mass concentration in Kumul was from March to September each year; high values of PM^0 mass concentration in Tazhong and Hotan were distributed from March to August and the average concenlration changed from 500 to 1,000 gg/m3, respectively. (4) The average seasonal concentration changes of PM10 in Kumul, Tazhong and Hotan were: spring 〉 summer 〉 autumn 〉 winter; the highest average concentration of PMl0in Tazhong, was about 1,000 gg/m3 in spring and between 400 and 900 gg/m3 in summer, and the average concentration was lower in autumn and winter, basically between 200 and 400 gg/m3. (5) PMl0 concentration during the sandstorm season was just over two times the con- centration of the non-sandstorm season in Kumul, Tazhong and Hotan. The average concentrations of sandstorm season in Tazhong were 6.2 and 3.6 times the average concentrations of non-sandstorm season in 2004 and 2008, respectively. (6) The mass concentra- tion of PM10 had the following sequence during the dust weather: clear day 〈 floating dust 〈 floating and blowing dust 〈 sandstorm. The wind speed directly affects the concentration of PM10 in the atmosphere, the higher the wind speed, the higher the mass concen- tration. Temperature, relative humidity and bammelric pressure are important factors affecting the strength of storms, which could also indirectly affect the concentration change of PM~ 0 in the atmosphere. 展开更多
关键词 dust aerosol dust weather mass concentration effect factors Taklimakan Desert
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Analysis of mass concentration of atmospheric particulate matter in a sandstorm course and its affecting factors in the Taklimakan Desert 被引量:3
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作者 XinChun Liu YuTing Zhong +3 位作者 Qing He XingHua Yang Ali Mamtimin Wen Huo 《Research in Cold and Arid Regions》 2012年第3期259-264,共6页
During the course of a major sandstorm from April 17 to April 23, 2008 in the Taklimakan Desert, data pertaining to the mass concentrations of different-sized atmospheric particulate matter were observed continuously ... During the course of a major sandstorm from April 17 to April 23, 2008 in the Taklimakan Desert, data pertaining to the mass concentrations of different-sized atmospheric particulate matter were observed continuously with Grimm 1.108, Thermo RP 1400a, TSP, and CAWS-600 instruments. The results showed that: (1) during the entire sandstorm process there were some dif- ferences between the daily mean particle concentration peaks and the hourly mean particle concentration peaks because the actual sandstorm lasted for only about 4 hr, whereas more particles were accumulated in the floating dust days before and after the actual sandstorm; (2) the intensity of the sandstorm was enhanced with the increase of wind speed, and this was related to the peak mass concentrations of atmospheric particulate matter; the wind speed directly affected the concentration of atmospheric particulate matter: the higher the wind speed, the higher the mass concentration (〉0.23 μm was 39,496.5 μg/m^3, and 〉20.0 μm was 5,390.7μg/m^3); (3) the concentration changes of PM10 and TSP were also related to the course and intensity of the sandstorm; and (4) the mass concentration of atmospheric particulate matter had the following sequence during the dust weather: clear day 〈 floating dust 〈 floating and blowing dust 〈 sandstorm. Temperature, relative humidity, and barometric pressure are important factors affecting the strength of storms, which could also indirectly affect the concentration change of atmospheric particulate matter. 展开更多
关键词 atmospheric particulate matter mass concentration SANDSTORM effect factors Taklimakan Desert
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Interferon beta(IFN-β) treatment exerts potential neuroprotective effects through neurotrophic factors and novel neurotensin/neurotensin high affinity receptor 1 pathway 被引量:2
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作者 Qin Wang Yang Mao-Draayer 《Neural Regeneration Research》 SCIE CAS CSCD 2015年第12期1932-1933,共2页
Multiple sclerosis(MS)is a chronic autoimmune disease of the central nervous system(CNS)characterized by coexisting processes of inflammation,demyelination,axonal neurodegeneration,and gliosis.It is the most commo... Multiple sclerosis(MS)is a chronic autoimmune disease of the central nervous system(CNS)characterized by coexisting processes of inflammation,demyelination,axonal neurodegeneration,and gliosis.It is the most common disabling neurological disease in young adulthood. 展开更多
关键词 IFN treatment exerts potential neuroprotective effects through neurotrophic factors and novel neurotensin/neurotensin high affinity receptor 1 pathway Interferon beta high
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Factors Analysis of Affecting Loading and Reinforcing Scheme of Large Goods in Railway 被引量:2
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作者 Xiaohong Li 《World Journal of Engineering and Technology》 2016年第3期60-68,共9页
Large goods transported in railway are kinds of special goods and they are very important in national construction. In order to transport safely, loading and reinforcing schemes must be made first. How to design a rea... Large goods transported in railway are kinds of special goods and they are very important in national construction. In order to transport safely, loading and reinforcing schemes must be made first. How to design a reasonable scheme will be affected by many factors. This paper presents the characteristic of the large goods, summarizes the process of designing a loading and reinforcing scheme of large good, then probes the factors of affecting the loading and reinforcing scheme and gives a detail analysis. It’s considered that those out-of-gauge and overweight degree of goods, center-of- gravity height of a loaded wagon, position of center-of-gravity of goods, type of wagon for using, reinforcement material and reinforcement method, transport expense and transport organization could affect a scheme in the aspects of safety, economy, rapidity and convenience. This conclusion will instruct and help to make a good scheme. 展开更多
关键词 Loading and Reinforcing Scheme Out-of-Gauge Goods Overweight Goods Rail Freight Transportation effecting Factor
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Spatial Distribution Pattern of the Steppe Toad-headed Lizard(Phrynocephalus frontalis) and Its Influencing Factors 被引量:1
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作者 Xue LIAN Zhigang JIANG +3 位作者 Xiaoge PING Songhua TANG Junhuai BI Chunwang LI 《Asian Herpetological Research》 SCIE 2012年第1期46-51,共6页
Spatial distribution patterns are associated with life history and behavioral adaptations of animals. For studying the spatial distribution pattern of the steppe toad-headed lizard(Phrynocephalus frontalis) and its in... Spatial distribution patterns are associated with life history and behavioral adaptations of animals. For studying the spatial distribution pattern of the steppe toad-headed lizard(Phrynocephalus frontalis) and its influencing factors,we conducted experiments in Hunshandake Sandy Land in Inner Mongolia,China in July 2009. By calculating the clustered indices,we found that the lizard was aggregately distributed when the sampling quadrat was smaller than 10 m × 10 m,and uniformly distributed when it was greater than 10 m × 10 m. The Nearest Neighbor Rule showed a clustering distribution pattern for P. frontalis and the distribution pattern was quadrat-sampling dependent. Furthermore,the cluster was determined by environmental factors when the sampling quadrat was smaller than 20 m × 20 m,but it was determined by both environmental factors and characteristics of the lizard when it was larger than 20 m × 20 m. Our results suggested that the steppe toad-headed lizards tended to aggregate into suitable habitat patches in desert areas. Additionally,we discussed that the lizard aggregation could be potentially used as an indictor of movement of sand dunes. 展开更多
关键词 sand lizard Phrynocephalus frontalis spatial distribution environmental factor quadrat-sampling effect
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ISOTHERMAL EFFECTIVENESS FACTORS FOR NONUNIFORM ACTIVE CATALYST
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作者 袁权 黄彬堃 李京山 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 1985年第1期147-156,共10页
Isothermal effectiveness factors for slab,cylinder and sphere shaped catalysts with uniform or nonuni-form intrinsic activity profiles have been investigated.In the case of zero-,first- and second-order kinetics,the e... Isothermal effectiveness factors for slab,cylinder and sphere shaped catalysts with uniform or nonuni-form intrinsic activity profiles have been investigated.In the case of zero-,first- and second-order kinetics,the effectiveness factors of pellets with increasing activity towards the pellet surface are larger than that ofuniform active catalyst,and they are proportional to the square root of the activity at the pellet surfacewith significant diffusion effect.The effectiveness factor-Thiele modulus curves which are valid for bothuniform and nonuniform catalysts have been obtained with the Thiele modulus modified by equivalent thick-hess of effective layer of the catalyst.Thus,the effectiveness factor for nonuniform active catalyst could bepredicted with a maximun deviation of 5% in the case of significant or insignificant diffusion effect but 10%in general. 展开更多
关键词 ISOTHERMAL EFFECTIVENESS factors FOR NONUNIFORM ACTIVE CATALYST IND
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ELECTROCARBOXYLATION OF ORGANIC COMPOUNDS WITH CARBON DIOXIDE CATALYTZED BY METALLOPORPHYRINS(Ⅳ)——EFFECT OF VARIOUS FACTORS ON ELECTROCARBOXYLATION
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作者 Guo Dong ZHENG Qing DING +1 位作者 Qing Da AN Xi Zhang CAODepartment of Chemistry,Jilin University,Changchun,130023 Present adress:Dalian Institute of Light Industry. 《Chinese Chemical Letters》 SCIE CAS CSCD 1992年第5期357-358,共2页
The effects of various factors on the electrocarboxylation of organic compounds with carbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar- boxylation is -1.6 V(vs.SCE).A weak pr... The effects of various factors on the electrocarboxylation of organic compounds with carbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar- boxylation is -1.6 V(vs.SCE).A weak protic solvent methanol can enhance catalytic activity. Tetrabutylammonium iodide is the best one of five electrolytes.The yields and current efficiencies of electrocarboxylation are increased slowly as the concentration of catalyst increases. 展开更多
关键词 SCE EFFECT OF VARIOUS factors ON ELECTROCARBOXYLATION ELECTROCARBOXYLATION OF ORGANIC COMPOUNDS WITH CARBON DIOXIDE CATALYTZED BY METALLOPORPHYRINS
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FACTORS INFLUENCING THE EFFECT OF RADIOIMMUNOTHERAPY ON LIVER CANCER
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作者 范桢 汤钊猷 +2 位作者 刘康达 易企龙 张照寰 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 1992年第2期58-63,共6页
Factors influencing the therapeutic effect of radiolmmunotherapy with 131I labeled anti- human hepa-tocellular carcinoma (HCC) ferritin antibody (131I -FtAb) on thirty three patients with surgically proven unresectabl... Factors influencing the therapeutic effect of radiolmmunotherapy with 131I labeled anti- human hepa-tocellular carcinoma (HCC) ferritin antibody (131I -FtAb) on thirty three patients with surgically proven unresectable HCC were studied. Multi- variable analysis with Cox' s regression model revealed that the statistically sig-nifieant factors include tumor size, activity of 131I administered each time and the second-look resection. Survival of patients with tumor diameter less than 10 cm was higher than that of patients with tumor diameter more than 10 cm (1-year survival; 84% versus 50%) 3-year survival; 63% versus 9% ). Patients administered with 5. 55×108 Bq to 9. 25× 10(?) of 131I-FtAb each time yielded better effect than those administered with more than 9. 25×108 Bq of 131I -FtAb (1-year, survival: 86% ver- sus 55%; 3-year survival: 50% versus 18%). When tumor shrank, patients underwent second-look resection had a higher survival than those without receiving second- look resection (1- year survival, 80%versus 66 %; 3-year survival; 80% versus 11%). 展开更多
关键词 HCC factors INFLUENCING THE EFFECT OF RADIOIMMUNOTHERAPY ON LIVER CANCER AFP
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The effects of the environmental factors on Laminaria disease caused by alginic acid decomposing bacteria
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作者 Ding Meili Institute of Oceanology, Academia Sinica, Qingdao 266071, China 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1992年第1期123-130,共8页
-The rot disease of Laminaria occurs often in nurseries of sporeling and commercial cultivation in the sea and results in economic loss greatly. Usually the disease outbreaks accompanied with massive multiplication of... -The rot disease of Laminaria occurs often in nurseries of sporeling and commercial cultivation in the sea and results in economic loss greatly. Usually the disease outbreaks accompanied with massive multiplication of alginic acid decomposing bacteria. From the section of the decaying Lamuutria which resulted from the inoculation of alginic acid decomposing bacteria, it was observed that the bacteria invaded the epiderm of the Laminaria surface at first, then entered the ex-odermis, endodermis and pith. In addition, there were a great amount of bacteria in the intercellular region and a lot of free cells of the algae in the decaying areas. The wall of some free cells was decomposed, which led to soft tissue or disintegration. Alginic acid decomposing bacteria are normal epiphytic microorganisms growing on Lamuutria surface. These bacteria do not cause disease at normal environmental conditions. The experiments showed that the unfavourable conditions, e. g. , wounding, overcrowding, high temperature reduced the ability of antibacterial activity and made the algae more susceptible to the pathogens and favoured the multiplication of alginic acid decomposing bacteria and finally led to the disease outbreak. The unfavourable environmental factors which resulted from a variety of reasons were the main cause of the disease. 展开更多
关键词 The effects of the environmental factors on Laminaria disease caused by alginic acid decomposing bacteria ACID
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Effect of ocean environmental factors on sound absorption by boric acid relaxation in sea water
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作者 Qiu Xinfang( Received May 17, 1990 accepted August 20, 1990) 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1991年第2期271-280,共10页
By using the expressions for the maximum absorption per wavelength (αλ),and the relaxation frequency fr of the boric acid relaxation derived previously by the author and employing the related oceanographic literatur... By using the expressions for the maximum absorption per wavelength (αλ),and the relaxation frequency fr of the boric acid relaxation derived previously by the author and employing the related oceanographic literatures, the effects of pressure, temperature, pH and salinity on (αλ)r and ∫r of the boric acid relaxation in sea water have been estimated. Results show that ( αλ), not only increases with pH but also increases approximately linearly with pressure and temperature, and is nearly proportional to the 1. 35 power of salinity. However, pressure, pH and salinity have negligible effect on ∫r; therefore, ∫r, can be approximately expressed as a function of temperature only. Comparisons of the predicted with the measured ( αλ)r and ∫r in different ocean areas are given. 展开更多
关键词 Effect of ocean environmental factors on sound absorption by boric acid relaxation in sea water ACID
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Modeling the Synergetic Effect of Various Factors on Chloride Transport in Nonsaturated Concrete
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作者 张小刚 LU Zhaohui +2 位作者 王淑萍 ZHOU Tianhai XING Feng 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第6期1336-1346,共11页
Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete(RC) structure, especially when the concrete is in a saturated state. However, the single mechanism of di... Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete(RC) structure, especially when the concrete is in a saturated state. However, the single mechanism of diffusion is not able to describe the actual chloride ingress in the nonsaturated concrete. Instead, it is dominated by the interaction of diffusion and convection. With the synergetic effects of various factors taken into account, this study aimed to modify and develop an analytical convection- diffusion coupling model for chloride transport in nonsaturated concrete. The model was verified by simulation of laboratory tests and field measurement. The results of comparison study demonstrate that the analytical model developed in this study is efficient and accurate in predicting the chloride profiles in the nonsaturated concrete. 展开更多
关键词 RC structures nonsaturated concrete chloride transport synergetic effect analytical convection-diffusion model influence factors
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Effects Of Subjective Factors On Second Language Learnig(L2L)
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《兵团教育学院学报》 1998年第1期46-49,共4页
In order to promote the activeness and initiative of learners and allow them to take theirlearning advantages,a teacher should be fully aware of the psychological process and models ofL2L.For no matter how well learn... In order to promote the activeness and initiative of learners and allow them to take theirlearning advantages,a teacher should be fully aware of the psychological process and models ofL2L.For no matter how well learners can command a language,their subjective incentives play adecisive role,that is the case particularly for non—Eniglish majors,who are always exposed tocrowded,serious and teacher—centred learning contexts. 展开更多
关键词 TH Effects Of Subjective factors On Second Language Learnig L2L
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SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN COMPLEX OXIDESⅢ.EFFECT OF THE CRYSTAL ENVIRONMENT AND CHEMICAL FACTORS ON LUMINESCENCE PROPERTIES OF EUROPIUM (Ⅱ) ION
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作者 孙家跃 石春山 李有谟 《Journal of Rare Earths》 SCIE EI CAS CSCD 1990年第2期110-116,共7页
In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond d... In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f^65d energy band in cubic or in octahedral fields will be inversely proportional to R^5,where R is the distance of Eu^(2+) to oxygen ligand.The value of R affects slightly the location of the centre of 4f^65d energy band.According to the exper- imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites of Eu^(2+) and degree of covalency of Eu-O bond on luminescence properties of Eu^(2+).Some regularity of fluorescence spectrum was observed. In alkali-alkaline earth-phosphates,the splitting extent of 4f^65d band (△E) becomes smaller as the Eu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emission peak of Eu^(2+) will shift to shorter wavelength with the increase of x's value. The crystal structure data show that Eu^(2+) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-field and covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu^(2+) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu^(2+) produces ultraviolet fluorescence. 展开更多
关键词 Eu SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN COMPLEX OXIDES EFFECT OF THE CRYSTAL ENVIRONMENT AND CHEMICAL factors ON LUMINESCENCE PROPERTIES OF EUROPIUM ION
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Simplified Penman-Monteith Equation Determined by Temperature-Based Global Radiation Data and Its Multilocal Validation under Subhumid Climatic Conditions in Hungary
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作者 Zoltán Varga-Haszonits Éva Szalka +3 位作者 Dávid Vasas Zsolt Giczi Pál Szakál Tamás Szakál 《Atmospheric and Climate Sciences》 2023年第4期455-465,共11页
The extent to which specific climatic factors influence evapotranspiration under subhumid conditions in Hungary was investigated. The reference evapotranspiration, calculated with the internationally accepted Penman-M... The extent to which specific climatic factors influence evapotranspiration under subhumid conditions in Hungary was investigated. The reference evapotranspiration, calculated with the internationally accepted Penman-Monteith equation proposed by FAO, was considered. The results show that the influence of radiation, which provides energy for evaporation, is the strongest factor and that the influence of global radiation alone is very strong. Taking into account that radiation was measured under rather limited conditions in space and time, global radiation was calculated using the Hargreaves method based on temperature. Accordingly, we have defined a formula based on temperature-based global radiation and verified the data obtained with the Penman-Monteith formula calculated for 14 meteorological stations. The verification gave good results, therefore the method can be used for practical purposes in the subhumid conditions of Hungary based on the data of the nearest meteorological station. 展开更多
关键词 effecting factors Sensitivity Analysis Global Radiation Multilocal Validation Estimation Error
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Role of grain boundary networks in vortex motion in superconducting films
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作者 刘宇 薛峰 苟晓凡 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第12期528-533,共6页
We study the vortex dynamics of the polycrystalline superconductors in the presence of both random point defects and the generated grain boundary(GB) networks with Voronoi diagram. The synergistic effect of adjacent G... We study the vortex dynamics of the polycrystalline superconductors in the presence of both random point defects and the generated grain boundary(GB) networks with Voronoi diagram. The synergistic effect of adjacent GBs on restricting the vortex motion in intragranular region is proposed and the corresponding intensity factor of the synergistic effect which characterizes the strength of the synergistic restriction of adjacent grain boundaries is also determined in the present work.The interconnected GBs offer easy-flow channels for vortices in addition to pinning effects on the vortices. The combined channels and the vortex flow patterns in the superconducting film are analyzed in detail from molecular dynamics simulations. Furthermore, it is discovered that the critical current increases with the decrease of magnetic field intensity,temperature, and the average grain size. The large number of vortices results in the enhanced repulsive interaction forcing the vortices to move out from the GBs. The thermal depinning from GBs leads to the lower Lorentz force range. The increase of the grain size causes the number of GBs to decrease. In summary, these effects leads the critical current to become a decreasing function of magnetic field, temperature, and grain size. 展开更多
关键词 grain boundary network Voronoi tessellation synergistic effect intensity factor of synergistic effect vortex motion combined channels
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