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Preparation of Well Dispersed and Ultra-Fine Ce(Zr)O_2 Mixed Oxide by Mechanochemical Processing 被引量:2
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作者 程昌明 李永绣 +1 位作者 周雪珍 陈伟凡 《Journal of Rare Earths》 SCIE EI CAS CSCD 2004年第6期775-779,共5页
Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the cryst... Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains. 展开更多
关键词 ceria-zirconia mixed oxide ultra-fine powders mechanochemical process rare earths
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NITROGEN NUTRIENT MECHANISM IN SECONDARY SUCCESSION PROCESS OF THE MIXED BROAD-LEAVED/ KOREAN PINE (PINUS KORAIENSIS) FOREST 被引量:1
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作者 李玉文 王业遽 《Journal of Northeast Forestry University》 SCIE CAS CSCD 1995年第3期100-104,共5页
Chemical and biochemical analysis methods were used to monitor the vedations of nitrogen nutrient among the dominance trees species in secondary succession process of the mixed broad - leaved/Korean pine forest on Cha... Chemical and biochemical analysis methods were used to monitor the vedations of nitrogen nutrient among the dominance trees species in secondary succession process of the mixed broad - leaved/Korean pine forest on Changbai Mountains, Northeast China. Amounts of total nitrogen, anunonium and NRA in soils of virgin broad-leaved/Korean pine forest which is in climax were higher than those of secondary birch forests those are in succession Stage. The amount of nitrate was in the other hand. In climax, dominance trees species are tolerant mesophytic trees such as Pinus Koraiensis, Tilia amurensis, Acer mono and also Fraxinus mandshurica, they are all ammonium + nitrate adapted species, but they show a preference for the anunonium rather than those of the pioneer trees species in secondary birch forest, such as Populus davidiava and Betula platyphylla. Because they have more ammonium in their leaves and roots, especially Pinus koraiensis. Populus davidvana and Betula plaaphlla are intolerant trees, amounts of nitrate and total nitrogen is higher in their leaves and roots and also NRA in their leaves, so they preference for the nitrate rather than the others.In secondary birch forest, the regeneration trees species adapt their nitroggn nutrient to the variation of nitrogen nutrient situation in soil, finally they could survival well and the secondary birch forest would succession to climax. In climax, dominance trees species adapt their Nitrogen nutrient to the situation in soil and there are not strong competition in nitrogen nutrient among them, so they can coexist well and keep the climax as stable vegetation. 展开更多
关键词 Nitrogen nutrient mechanism Secondary succession process mixed broad-leaved/Pinus koraiensis (Korean pine) forest Stability of climax
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CONTINUOUS TIME MIXED STATE BRANCHING PROCESSES AND STOCHASTIC EQUATIONS 被引量:1
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作者 Shukai CHEN Zenghu LI 《Acta Mathematica Scientia》 SCIE CSCD 2021年第5期1445-1473,共29页
A continuous time and mixed state branching process is constructed by a scaling limit theorem of two-type Galton-Watson processes.The process can also be obtained by the pathwise unique solution to a stochastic equati... A continuous time and mixed state branching process is constructed by a scaling limit theorem of two-type Galton-Watson processes.The process can also be obtained by the pathwise unique solution to a stochastic equation system.From the stochastic equation system we derive the distribution of local jumps and give the exponential ergodicity in Wasserstein-type distances of the transition semigroup.Meanwhile,we study immigration structures associated with the process and prove the existence of the stationary distribution of the process with immigration. 展开更多
关键词 mixed state branching process weak convergence stochastic equation system Wasserstein-type distance stationary distribution
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Pricing Model of Multiattribute Derivatives Based on Mixed Process
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作者 田军 彭灿 刘源 《Journal of Modern Transportation》 2000年第2期198-204,共7页
By Analyzing the behavior and character of derivative security, the authors established a pricing model of multiattribute derivative security whose underlying asset pricing process is a mixed process, and obtained a n... By Analyzing the behavior and character of derivative security, the authors established a pricing model of multiattribute derivative security whose underlying asset pricing process is a mixed process, and obtained a new model for option pricing of multiattribute derivatives based on mixed process, and improved some original results. 展开更多
关键词 pricing model multiattribute derivatives mixed process
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Enhanced nitrogen removal at low temperature with mixed anoxic/oxic process
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作者 Xiang-kun Li Ying-jun Yang +2 位作者 Gai-ge Liu Dou-dou Sun Xiao-chen Ma 《Water Science and Engineering》 EI CAS CSCD 2023年第1期67-75,共9页
Different hydraulic retention times(HRTs)were tested in a mixed anoxic/oxic(A/O)system at 5C and 10C to investigate the effects of HRT and carrier on nitrogen removal in wastewater at low temperatures.The results show... Different hydraulic retention times(HRTs)were tested in a mixed anoxic/oxic(A/O)system at 5C and 10C to investigate the effects of HRT and carrier on nitrogen removal in wastewater at low temperatures.The results showed that the addition of the fillers improved the treatment effect of each index in the system.With an optimal HRT of 7.5 h at 5C,the removal efficiencies of NHþ4-N and total nitrogen(TN)reached 91.2%and 75.6%,respectively.With an HRT of 6 h at 10C,the removal efficiencies of NHþ4-N and TN were 96.7%and 82.9%,respectively.The results of high-throughput sequencing showed that the addition of the suspended carriers in the aerobic zone could improve the treatment efficiency of nitrogen at low temperatures.The microbial analysis indicated that the addition of the suspended carriers enhanced the enrichment of nitrogen removal bacteria.Nitrospira,Nitrotoga,and Nitrosomonas were found to be the bacteria responsible for nitrification,and their relative concentrations on the biofilm at 5C and 10C accounted for 98.11%,92.79%,and 69.98%of all biological samples,respectively. 展开更多
关键词 Domestic sewage Low temperature mixed A/O process Nitrogen removal Bacterial community structure
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Influence of Processing Technology on Mooney Viscosity and Burning Time of Mixed Rubber
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作者 Qi Liu Hui Li 《Research and Application of Materials Science》 2019年第1期24-27,共4页
The influence of mixed rubber processing technology on Mooney viscosity and burning time was studied.The results showed that the Mooney viscosity of mixed rubber increased with the extension of the parking time,and th... The influence of mixed rubber processing technology on Mooney viscosity and burning time was studied.The results showed that the Mooney viscosity of mixed rubber increased with the extension of the parking time,and the burning time did not change significantly.With the increase of the number of thin pass,the Mooney viscosity of mixed rubber decreases continuously,and the burning time varies with different thin pass temperature. 展开更多
关键词 mixed RUBBER processING technology Mooney VISCOSITY BURNING TIME BoTong
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A Study on Mixed Effect Analysis of Polymeric Mixture by Means of Image Processing Technology
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作者 许正军 《Journal of China Textile University(English Edition)》 EI CAS 1998年第4期71-73,共3页
The mixed effect analysis of polymeric mixture by means of image processing technology is discussed here. Since the integration of image and digital analysis, this method has the advantages of both perceptibility and ... The mixed effect analysis of polymeric mixture by means of image processing technology is discussed here. Since the integration of image and digital analysis, this method has the advantages of both perceptibility and objectivity. With pixel distribution as the main measurement of mixed effect, it indicates that the method of image pro-cessing technology is a new way to assess the mixed effect of polymeric mixture and the properties of all kinds of mixers. 展开更多
关键词 DISTRIBUTIVE mixing image processing GREY dis-tribution PIXELS statistics
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The Marginal Rao-Blackwellized Particle Filter for Mixed Linear/Nonlinear State Space Models 被引量:16
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作者 Yin Jianjun Zhang Jianqiu Mike Klaas 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2007年第4期346-352,共7页
In this paper, the marginal Rao-Blackwellized particle filter (MRBPF), which fuses the Rao-Blackwellized particle filter (RBPF) algorithm and the marginal particle filter (MPF) algorithm, is presented. The state... In this paper, the marginal Rao-Blackwellized particle filter (MRBPF), which fuses the Rao-Blackwellized particle filter (RBPF) algorithm and the marginal particle filter (MPF) algorithm, is presented. The state space is divided into linear and non-linear parts, which can be estimated separately by the MPF and the optional Kalman filter. Through simulation in the terrain aided navigation (TAN) domain, it is demonstrated that, compared with the RBPF, the root mean square errors (RMSE) and the error variance of the nonlinear state estimations by the proposed MRBPF are respectively reduced by 29% and 96%, while the unique particle count is increased by 80%. It is also found that the MRBPF has better convergence properties, and analysis has shown that the existing RBPF is nothing more than a special case of the MRBPF. 展开更多
关键词 signal processing marginal Rao-Blackwellized particle filter SIMULATION mixed linear/nonlinear terrain aided navigation
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Study on Flow and Mixing Characteristics of Molten Steel in RH and RH-KTB Refining Processes 被引量:9
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作者 魏季和 郁能文 +3 位作者 樊养颐 马金昌 朱德平 杨森龙 《Journal of Shanghai University(English Edition)》 CAS 2002年第2期167-175,共9页
The flow and mixing characteristics of molten steel during the vacuum circulation refining, including RH(Ruhrstahl Heraeus) and RH KTB(Ruhrstahl Heraeus Kawasaki top blowing) processes, were investigated on a 1/5 ... The flow and mixing characteristics of molten steel during the vacuum circulation refining, including RH(Ruhrstahl Heraeus) and RH KTB(Ruhrstahl Heraeus Kawasaki top blowing) processes, were investigated on a 1/5 linear scale water model of a 90 t multifunction RH degasser. The circulation rate was directly and more accurately determined, using a new method by which the more reliable results can be obtained. The fluid flow pattern and flow field in the ladle were demonstrated, observed and analyzed. The mixing time of liquid in the ladle was measured using electrical conductivity method. The residence time distribution in the RH model was obtained by tracer response technique. The influence of the main technological and geometric factors, including the gas top blowing (KTB) operation, was examined. The results indicated that the circulation rate of molten steel in the RH degasser can be fairly precisely calculated by the formula: Q lp =0.0333 Q 0.26 g D 0.69 u D 0.80 d(t/min), where Q g-the lifting gas flow rate (NL/min); D u and D d-the inner diameters of the up and down snorkels (cm), respectively. The maximum value of circulation rate of molten steel in the case of the 30 cm diameters either of the up and down snorkels for the RH degasser (the “saturated” rate) is approximately 31 t/min. The corresponding gas flow rate is 900 NL/min. Blowing gas into the vacuum chamber through the top lance like KTB operation does not markedly influence the circulatory flow and mixing characteristics of the RH process under the conditions of the present work. There exist a major loop and a large number of small vortices and eddies in the ladle during the RH refining process. A liquid liquid two phase flow is formed between the descending stream from the down snorkel and the liquid around the stream. All of these flow situation and pattern will strongly influence and determine the mixing and mass transfer in the ladle during the refining. The correlation between the mixing time and the stirring energy density is τ m∝ε -0.50 for the RH degasser. The mixing time rapidly shortens with an increase in the lifting gas flowrate. At a same gas flow rate, the mixing times with the up and down snorkel diameters either of 6 and 7 cm are essentially same. The 30 cm diameters either of the up and down snorkels for the RH degasser would be reasonable. The concentration time curve showed that three circulation cycles are at least needed for complete mixing of the liquid steel in the RH degasser. 展开更多
关键词 refining of molten steel RH process RH KTB process FLOW mixing water modeling.
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On the sub-mixed fractional Brownian motion 被引量:11
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作者 El-Nouty Charles Zili Mounir 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2015年第1期27-43,共17页
Let {S t H, t ≥ 0) be a linear combination of a Brownian motion and an independent sub-fractional Brownian motion with Hurst index 0 〈 H 〈 1. Its main properties are studied. They suggest that SH lies between the ... Let {S t H, t ≥ 0) be a linear combination of a Brownian motion and an independent sub-fractional Brownian motion with Hurst index 0 〈 H 〈 1. Its main properties are studied. They suggest that SH lies between the sub-fractional Brownian motion and the mixed fractional Brownian motion. We also determine the values of H for which SH is not a semi-martingale. 展开更多
关键词 mixed Gaussian processes sub-fractional Brownian motion no stationary increments semi-martingales convexity.
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Pollutant mixing and transport process via diverse transverse release positions in a multi-anabranch river with three braid bars 被引量:4
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作者 Zu-lin HUA Wei JI +1 位作者 Ning-ning SHAN Wei WU 《Water Science and Engineering》 EI CAS CSCD 2013年第3期250-261,共12页
A multi-anabranch river with three braid bars is a typical river pattern in nature, but no studies have been conducted to describe mixing characteristics of pollutants in the river. In this study, a physical model of ... A multi-anabranch river with three braid bars is a typical river pattern in nature, but no studies have been conducted to describe mixing characteristics of pollutants in the river. In this study, a physical model of a typical multi-anabranch river with three braid bars was established to explore the pollutant mixing characteristics in different branches. The multi-anabranch reach was separated into seven branches, B1, B2, B3, B4, B5, B6, and BT, by three braid bars. Five tracer release positions located 2.9 m upstream from the inlet section of the multi-anabranch reach were adopted, and the distances from the five positions to the left bank of the upstream main channel were 1/6B, 1/3B, 1/2B, 2/3B, and 5/6B (B is the width of the upstream main channel), respectively. The longitudinal velocities and pollutant concentrations in the seven branches were measured. The planar flow field and mixing characteristics of pollutants from the bottom to the surface in the multi-anabranch river were obtained and analyzed. The results show that the pollutant release positions are the main influencing factors in the pollutant transport process, and the diversion points and pollutant release positions jointly influence the percentage ratios of the pollutant fluxes in branches B 1, B2, and B3 to the pollutant flux in the upstream main channel. 展开更多
关键词 multi-anabranch river braid bar pollutant mixing characteristic pollutanttransport process
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A new low-cost method of reclaiming mixed foundry waste sand based on wet-thermal composite reclamation 被引量:6
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作者 Fan Zitian Liu Fuchu +1 位作者 Long Wei Li Guona 《China Foundry》 SCIE CAS 2014年第5期402-407,共6页
A lot of mixed clay-resin waste sand from large-scale iron foundries is discharged every day; so mixed waste sand reclamation in low cost and high quality has a great realistic significance. In the study to investigat... A lot of mixed clay-resin waste sand from large-scale iron foundries is discharged every day; so mixed waste sand reclamation in low cost and high quality has a great realistic significance. In the study to investigate the possibility of reusing two types of waste foundry sands, resin bonded sand and clay bonded sand which came from a Chinese casting factory, a new low-cost reclamation method of the mixed foundry waste sand based on the wet-thermal composite reclamation was proposed. The waste resin bonded sand was first reclaimed by a thermal method and the waste clay bonded sand was reclaimed by a wet method. Then, hot thermal reclaimed sand and the dehydrated wet reclaimed sand were mixed in certain proportions so that the hot thermal reclaimed sand dried the wet reclaimed sand leaving some water. The thermal reclamation efficiency of the waste resin bonded sand was researched at different heat levels. The optimized wet reclamation process of the waste clay bonded sand was achieved by investigating the effects of wet reclamation times, sand-water ratio and pH value on the reclaimed sand characteristics. The composite reclamation cost also was calculated. The research results showed that the properties of the mixed reclaimed sand can satisfy the application requirements of foundries; in which the temperature of the thermal reclamation waste resin bonded sand needs to be about 800 oC, the number of cycles of wet reclamation waste clay bonded sand should reach four to five, the optimal sand-water ratio of wet reclamation is around 1:1.5, and the pH value should be adjusted by adding acid. The mass ratio of hot thermal reclaimed sand to dehydrated wet reclaimed sand is about 1:2.5, and the composite reclaimed sand cost is around 100 yuan RMB per ton. 展开更多
关键词 sand casting process mixed waste sand HIGH-QUALITY LOW-COST sand reclamation
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Use of two-stage dough mixing process in improving water distribution of dough and qualities of bread made from wheat–potato flour 被引量:4
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作者 YIN Jian CHENG Li +4 位作者 HONG Yan LI Zhao-feng LI Cai-ming BAN Xiao-feng GU Zheng-biao 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2021年第1期300-310,共11页
The two-stage dough mixing process was innovated to improve the qualities of bread made from potato flour(PF) and wheat flour at a ratio of 1:1(w/w). The final dough was first prepared from wheat flour before being ad... The two-stage dough mixing process was innovated to improve the qualities of bread made from potato flour(PF) and wheat flour at a ratio of 1:1(w/w). The final dough was first prepared from wheat flour before being added with PF. The effects of the method on enhancing the dough qualities were verified, and the distribution of water in gluten-gelatinized starch matrix of the doughs was investigated. We observed that the bread qualities were improved, as reflected by the increase of specific volume from 2.26 to 2.96 m L g^–1 and the decrease of crumb hardness from 417.93 to 255.57 g. The results from rheofermentometric measurements showed that the dough mixed using the developed mixing method had higher maximum dough height value, time of dough porosity appearance, and gas retention coefficient, as well as enhanced gluten matrix formation compared to that mixed by the traditional mixing method. The results from low-field nuclear magnetic resonance confirmed that the competitive water absorption between gluten and gelatinized starch could restrict the formation of gluten network in the dough mixed using the traditional mixing process. Using the novel mixing method, gluten could be sufficiently hydrated in stage 1, which could then weaken the competitive water absorption caused by gelatinized starch in stage 2;this could also be indicated by the greater mobility of proton in PF and better development of gluten network during mixing. 展开更多
关键词 gelatinized starch gluten network potato flour water distribution two-stage dough mixing process
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Study on Hydrocracking of VGO Derived from Kazakhstan-Russian Mixed Crude 被引量:1
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作者 Dong Yuancheng Duan Yongsheng +3 位作者 Zou Shiying Wang Jian Ye Xingbin Yang Jianxin (Research Institute of PetroChina Dushanzi Petrochemical Company, Dushanzi 833600) 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2006年第3期27-32,共6页
This article investigates the influence of the property of VGO derived from the Kazakhstan- Russian mixed crude on the hydrocracking catalyst. The influence of reaction temperature, reaction pressure, space velocity a... This article investigates the influence of the property of VGO derived from the Kazakhstan- Russian mixed crude on the hydrocracking catalyst. The influence of reaction temperature, reaction pressure, space velocity and hydrogen/oil ratio on the distribution and quality of products was analyzed with the optimal process regime determined, when the VGO was hydrocracked in the presence of the FC-16 catalyst. 展开更多
关键词 Kazakhstan-Russian mixed crude VGO HYDROCRACKING optimal process parameters
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Effects of Assistant Solvents and Mixing Intensity on the Bromination Process of Butyl Rubber 被引量:1
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作者 王伟 邹海魁 +3 位作者 初广文 向阳 彭晗 陈建峰 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第4期398-404,共7页
A slow bromination process of butyl rubber (IIR) suffers from low efficiency and low selectivity (S) of target-product. To obtain suitable approach to intensify the process, effects of assistant solvents and mixin... A slow bromination process of butyl rubber (IIR) suffers from low efficiency and low selectivity (S) of target-product. To obtain suitable approach to intensify the process, effects of assistant solvents and mixing inten-sity on the bromination process were systemically studied in this paper. The reaction process was found constantly accelerated with the increasing dosage and polarity of assistant solvent. Hexane with 30%(by volume) dichloro-methane was found as the suitable solvent component, where the stable conversion of 1,4-isoprene transferring to target product (xA1s) of 80.2%and the corresponding S of 91.2%were obtained in 5 min. The accelerated reaction process was demonstrated being remarkably affected by mixing intensity until the optimal stirring rate of 1100 r&#183;min-1 in a stirred tank reactor. With better mixing condition, a further intensification of the process was achieved in a ro-tating packed bed (RPB) reactor, where xA1s of 82.6% and S of 91.9% were obtained in 2 min. The usage of the suitable solvent component and RPB has potential application in the industrial bromination process intensification. 展开更多
关键词 bromination of butyl rubber process intensitication assistant solvent mixing intensity
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Study on mixing and segregation behaviors in particulate fluidized bed system for mineral processing 被引量:2
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作者 Sahu S.N. Sahu A.K. Biswal S.K. 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2015年第3期459-464,共6页
In order to identify the mixing and segregation behaviors in a mineral processing operation, present study aimed on the hydrodynamics of solid–liquid fluidization. The study was carried out in a fluidization column w... In order to identify the mixing and segregation behaviors in a mineral processing operation, present study aimed on the hydrodynamics of solid–liquid fluidization. The study was carried out in a fluidization column with tapings at different height of the bed to collect the sample. The binary particles considered in this study are hematite(4800 kg/m3) and quartz(2600 kg/m3) at different size fractions in the range of average size 87×10^(-6)m to 400×10^(-6)m. It is observed that for various binary mixtures, both quartz and hematite particles share the equal composition by mass(50%) at a particular height of fluidized bed, referred as ‘‘locus point'' of mixing. Study indicates that the mixing zone volume will increase for a continuous fluidized bed plant operation. It is observed that the number of locus points varies from 1 to 3 signifying their dependency on the size ratios of binary mixture. Whenever, the difference in terminal velocity between quartz and hematite particles approaches to zero, mixing is enhanced.Further, the present study is extended to find the segregation index for the different size ratios of quartz and hematite particles. It is evident that depending on the size ratios, various regions such as complete segregation, partial mixing and complete mixing can be observed. 展开更多
关键词 Liquid-solid fluidization mixing Segregation Locus point Mineral processing
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Effects of intermixing process on bonding strength of IBED CrN coatings
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作者 唐宾 朱晓东 +1 位作者 胡奈赛 何家文 《中国有色金属学会会刊:英文版》 CSCD 2000年第1期64-68,共5页
The coating substrate bonding strengths under different intermixing processes were evaluated by scratch and spherical rolling contact fatigue methods. The results show that for low bombarding energy of N ions dynamic ... The coating substrate bonding strengths under different intermixing processes were evaluated by scratch and spherical rolling contact fatigue methods. The results show that for low bombarding energy of N ions dynamic recoiling at 10 keV and 20 keV, the coating layers are of excellent bonding strengths. The bonding strength of CrN coating with 40 keV static recoiling is higher than that of low energy(20 keV). On the other hand, the bonding strength of coating with 40 keV dynamic recoiling is much lower than that of static recoiling at the same energy and even less than that of dynamic recoiling intermixings at 10 keV and 20 keV energy. The results of scratch and spherical rolling contact fatigue methods exhibit the same trend for each group of recoiling methods, yet the results of the scratch and fatigue tests for two groups do not agree with each other. 展开更多
关键词 IBED CRN COATING INTER mixING processes BONDING STRENGTH
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Fidelity between Gaussian mixed states with quantum state quadrature variances
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作者 张海龙 周淳 +1 位作者 史建红 鲍皖苏 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第4期57-62,共6页
In this paper, from the original definition of fidelity in a pure state, we first give a well-defined expansion fidelity between two Gaussian mixed states. It is related to the variances of output and input states in ... In this paper, from the original definition of fidelity in a pure state, we first give a well-defined expansion fidelity between two Gaussian mixed states. It is related to the variances of output and input states in quantum information pro- cessing. It is convenient to quantify the quantum teleportation (quantum clone) experiment since the variances of the input (output) state are measurable. Furthermore, we also give a conclusion that the fidelity of a pure input state is smaller than the fidelity of a mixed input state in the same quantum information processing. 展开更多
关键词 FIDELITY mixed state quantum clone quantum information processing
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A Central Limit Theorem of Branching Process with Mixing Interactions
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作者 Liu Yan\|yan School of Mathematics and Statistics, Wuhan University, Wuhan 430072, Hubei, China 《Wuhan University Journal of Natural Sciences》 CAS 2002年第3期261-266,共6页
In this paper, we discuss a class of branching processes which generalize the classical Galton-Watson processes: we permit some mixing dependence between the offspring in the same generation. A central limit theorem i... In this paper, we discuss a class of branching processes which generalize the classical Galton-Watson processes: we permit some mixing dependence between the offspring in the same generation. A central limit theorem is established and the Hausdorff dimension on such kind of branching process is given. 展开更多
关键词 Key words mixing dependent Galton Watson process Hausdorff dimension
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Adolescents’ perspectives on a school-based physical activity intervention:A mixed method study
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作者 Stephanie T.Jong Caroline H.D.Croxson +8 位作者 Cornelia Guell Emma R.Lawlor Campbell Foubister Helen E.Brown Emma K.Wells Paul Wilkinson Anna Vignoles Esther M.F.van Sluijs Kirsten Corder 《Journal of Sport and Health Science》 SCIE 2020年第1期28-40,F0003,共14页
Purpose'. To examine adolescent experiences and perspectives of the GoActive intervention (ISRCTN31583496) using mixed methods processevaluation to determine satisfaction with intervention components and interpret... Purpose'. To examine adolescent experiences and perspectives of the GoActive intervention (ISRCTN31583496) using mixed methods processevaluation to determine satisfaction with intervention components and interpret a*dolescents experiences of the intervention process in order toprovide insights for future intervention design.Methods'. Participants (n = 1542;13.2 土 0.4 years, mean 土 SD) provided questionnaire data at baseline (shyness, activity level) and post-intervention(intervention acceptability, satisfaction with components). Between-group differences (boys vs. girls and shy/inactive vs. others) weretested with linear regression models, accounting for school clustering. Data from 16 individual interviews (shy/inactive) and 11 focus groupswith 48 participants (mean = 4;range 2—7) were thematically coded. Qualitative and quantitative data were merged in an integrative mixedmethods convergence matrix, which denoted convergence and dissonance across datasets.Results'. Effect sizes for quantitative results were small and may not represent substantial between-group differences. Boys (vs. girls) preferredclass-based sessions (0 = 0.2, 95% confidence interval (CI): 0.1—0.3);qualitative data suggested that this was because boys preferred competition,which was supported quantitatively (0 = 0.2, 95%CI: 0.1-0.3). Shy/inactive students did not enjoy the competition (0 = -0.3, 95%CI:—0.5 to —0.1). Boys enjoyed trying new activities more (0 = 0.1, 95%CI: 0.1 -0.2);qualitative data indicated a desire to try new activities acrossall subgroups but identified barriers to choosing unfamiliar activities with self-imposed choice restriction leading to boredom. Qualitative datahighlighted critique of mentorship;adolescents liked the idea, but older mentors did not meet expectations.Conclusion. We interpreted adolescent perspectives of intervention components and implementation to provide insights into future complexinterventions aimed at increasing young people's physical activity in school-based settings. The intervention component mentorship was liked inprinciple, but implementation issues undesirably impacted satisfaction;competition was disliked by girls and shy/inactive students. The resultshighlight the importance of considering gender differences in preference of competition and extensive mentorship training. 展开更多
关键词 ADOLESCENT INTERVENTION mixed methods Physical activity process evaluation
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