期刊文献+
共找到425篇文章
< 1 2 22 >
每页显示 20 50 100
Analysis of a landfill cover without geomembrane using varied particle sizes of recycled concrete
1
作者 Charles Wang Wai Ng Cheuk Lam Ng +4 位作者 Junjun Ni Haowen Guo Qi Zhang Qiang Xue Rui Chen 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第5期1263-1273,共11页
Previous studies have demonstrated the effectiveness of a novel three-layer landfill cover system constructed with recycled concrete aggregates(RCAs)without geomembrane in both laboratory and field.However,no systemat... Previous studies have demonstrated the effectiveness of a novel three-layer landfill cover system constructed with recycled concrete aggregates(RCAs)without geomembrane in both laboratory and field.However,no systematic investigation has been carried out to optimize the combination of the particle sizes for fine-grained RCAs(FRC)and coarse-grained RCAs(CRC)that can be used for the three-layer landfill cover system.The aim of this paper is to assist engineers in designing the three-layer landfill cover system under a rainfall of 100-year return period in humid climate conditions using an easily controlled soil parameter D10 of RCAs.The numerical study reveals that when D10 of FRC increases from 0.05 mm to 0.16 mm,its saturated permeability increases by 10 times.As a result,a larger amount of rainwater infiltrates into the cover system,causing a higher lateral diversion in both the top FRC and middle CRC layers.No further changes in the lateral diversion are observed when the D10 value of FRC is larger than 0.16 mm.Both the particle sizes of FRC and CRC layers are shown to have a minor influence on the percolation under the extreme rainfall event.This implies that the selection of particle sizes for the FRC and CRC layers can be based on the availability of materials.Although it is well known that the bottom layer of the cover system should be constructed with very fine-grained soils if possible,this study provides an upper limit to the particle size that can be used in the bottom layer(D10 not larger than 0.02 mm).With this limit,the three-layer system can still minimize the water percolation to meet the design criterion(30 mm/yr)even under a 100-year return period of rainfall in humid climates. 展开更多
关键词 Capillary barrier Landfill cover particle size Recycled concrete
下载PDF
Effects of Ru nanoparticle sizes confined in cavities of SBA-16 on the catalytic performance of Fischer-Tropsch synthesis reaction 被引量:1
2
作者 Jian Chen Jinlin Li +2 位作者 Yanxi Zhao Yuhua Zhang Jingping Hong 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2012年第6期673-679,共7页
Ru nanoparticles with different sizes confined in the cavities of mesoporous SBA-16 have been successfully synthesized by incipient wetness impregnation method with a Ru loading of 4 wt%. The catalysts were characteri... Ru nanoparticles with different sizes confined in the cavities of mesoporous SBA-16 have been successfully synthesized by incipient wetness impregnation method with a Ru loading of 4 wt%. The catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR, H2-TPD, O2-titration and TEM. The catalytic performance of Fischer-Tropsch synthesis over the catalyst was tested in a fixed-bed reactor. The addition of citric acid in the impregnation procedure shows a significant influence on the size of Ru nanoparticles. The selectivity to C5+ increases, while the selectivities to methane and C2-C4 light hydrocarbons decrease with Ru average particles size from 2.0 nm to 9.3 nm, . The Ru catalyst confined in the SBA-16 with average nanoparticle size of 5.3 nm gives the best activity. 展开更多
关键词 Fischer-Tropsch synthesis Ru catalyst SBA-16 particle sizes
下载PDF
Determination of Particle Sizes and Crystalline Phases on Colloidal Silicon Nanoparticle Suspensions
3
作者 S.M. Scholz and H Hofmann(Powder Technology Laboratory, Department of Materials Science, Swiss Federal Institiute of Technology Lausanne,CH-1015 Lausanne, Switzerland) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1999年第6期548-550,共3页
Particle size and crystallinity of silicon nanoparticles were determined by analyzing the optical extinction spectra of colloidal suspensions. Experimental results from these colloids were anaiyzed using Mie theory in... Particle size and crystallinity of silicon nanoparticles were determined by analyzing the optical extinction spectra of colloidal suspensions. Experimental results from these colloids were anaiyzed using Mie theory in connection with effective medium theory, in order to determine particle sizes and their internal structure with the simple technique of optical transmission spectroscopy. By modeling an effective refractive index for the particles, the crystalline volume fraction can be extracted from extinction spectra in addition to information about the size. The crystalline volume fraction determined in this way were used to calibrate the ratio of the Raman cross sections for nanocrystalline and amorphous silicon, which was found to be σc./σa = 0.66 展开更多
关键词 Determination of particle sizes and Crystalline Phases on Colloidal Silicon Nanoparticle Suspensions
下载PDF
Effect of proteins,polysaccharides,and particle sizes on sludge dewaterability 被引量:37
4
作者 SHAO Liming,HE Peipei,YU Guanghui,HE Pinjing State Key Laboratory of Pollution Control and Resources Reuse,Key Laboratory of Yangtze River Water Environment,College of Environmental Science and Engineering,Tongji University,Shanghai 200092,China 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2009年第1期83-88,共6页
Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins (PN) and polysaccharides (PS) in the sludge, the PN/PS ratio, the particle sizes, and their rela... Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins (PN) and polysaccharides (PS) in the sludge, the PN/PS ratio, the particle sizes, and their relationship with sludge dewaterability (as determined by capillary suction time, CST). The sludge flocs were stratified through centrifugation- and ultrasound-based method into four fractions: (1) slime, (2) loosely bound extracellular polymeric substances (LB-EPS), (3) tightly bound EPS (TB-EPS), and (4) pellet. The results showed that PN was mainly partitioned in the pellet (80.7%) and TB-EPS (9.6%) fractions, while PS distributed evenly in the four fractions. During hydrolysis and acidification, PN was transferred from the pellet and TB-EPS fractions to the slime fraction, but PS had no significant transfer trends. The mean particle sizes of the sludge flocs decreased with hydrolysis and acidification. The pH had a more significant influence on the dewaterability of sludge flocs than temperature. Sludge dewaterability during hydrolysis and acidification processes greatly deteriorated from 9.7 s at raw sludge to 340-450 s under alkaline conditions. However, it was just slightly increased under acidic conditions. Further investigation suggested that CST was affected by soluble PN, soluble PN/PS, and particle sizes of sludge flocs, but was affected slightly by total PN, PS, or PN/PS in the whole sludge flocs and other fractions (except slime). 展开更多
关键词 DEWATERABILITY extracellular polymeric substances particle size POLYSACCHARIDES PROTEINS sewage sludge
下载PDF
Characteristics of phosphorus adsorption by sediment mineral matrices with different particle sizes 被引量:6
5
作者 Yang XIAO Xiao-lian ZHU +3 位作者 Hao-ke CHENG Kai-jie LI Qi LU Dong-fang LIANG 《Water Science and Engineering》 EI CAS CSCD 2013年第3期262-271,共10页
The particle size of sediment is one of the main factors that influence the phosphorus physical adsorption on sediment. In order to eliminate the effect of other components of sediment on the phosphorus physical adsor... The particle size of sediment is one of the main factors that influence the phosphorus physical adsorption on sediment. In order to eliminate the effect of other components of sediment on the phosphorus physical adsorption, the sediment mineral matrices were obtained by removing inorganic matter, metal oxides, and organic matter from natural sediments, which were collected from the Nantong reach of the Yangtze River. The results show that an exponential relationship exists between the median particle size (Ds0) and specific surface area (Sg) of the sediment mineral matrices, and the fine sediment mineral matrix sample has a larger specific surface area and pore volume than the coarse sediment particles. The kinetic equations were used to describe the phosphorus adsorption process of the sediment mineral matrices, including the Elovich equation, quasi-first-order adsorption kinetic equation, and quasi-second-order adsorption kinetic equation. The results show that the quasi-second-order adsorption kinetic equation has the best fitting effect. Using the mass conservation and Langmuir adsorption kinetic equations, a formula was deduced to calculate the equilibrium adsorption capacity of the sediment mineral matrices. The results of this study show that the phosphorus adsorption capacity decreases with the increase of Ds0, indicating that the specific surface area and pore volume are the main factors in determining the phosphorus adsorption capacity of the sediment mineral matrices. This study will help understand the important role of sediment in the transformation of phosphorus in aquatic environments. 展开更多
关键词 sediment mineral matrix particle size specific surface area pore volume phosphorus adsorption
下载PDF
Powder electrochemical properties with different particle sizes of spinel LiAl_(0.05)Mn_(1.95)O_4 synthesized by sol-gel method 被引量:3
6
作者 YI Tingfeng WANG Dianlong +1 位作者 GAO Kun HU Xinguo 《Rare Metals》 SCIE EI CAS CSCD 2007年第4期330-334,共5页
An Al-doped spinel lithium manganese oxide was prepared by the adipic acid-assisted sol-gel method at 800℃, and the cathode materials (Liml0.05Mnl.9504) with different particle sizes were obtained through ball mill... An Al-doped spinel lithium manganese oxide was prepared by the adipic acid-assisted sol-gel method at 800℃, and the cathode materials (Liml0.05Mnl.9504) with different particle sizes were obtained through ball milling. The effects of particle size on the electrochemical performance of LiAl0.05Mnl.9504 samples were investigated by differential thermal analysis and thermogravimetry, X-ray diffraction, galvanostatic charge-discharge test, cyclic voltammetry, and electrochemical impedance spectroscopy. The results indicate that all samples with different particle sizes show the same pure spinel phase and good crystal structure; LiAlo.osMnl.9504 with Dso = 17.3 μm shows better capacity retention; LiAlo.osMnl.gsO4 cathode materials with small particle size have a bigger resistance of charge transfer than the large one, and the particle size has significant effects on the electrochemical performance of Al-doped spinel LiMn2O4 cathode materials. 展开更多
关键词 lithium ion battery LiAl0.05Mn1.95O4 electrochemical properties particle size
下载PDF
Study of deep transportation and plugging performance of deformable gel particles in porous media
7
作者 Wen-Jing Zhao Jing Wang +1 位作者 Zhong-Yang Qi Hui-Qing Liu 《Petroleum Science》 SCIE EI CAS CSCD 2024年第2期962-973,共12页
Deformable gel particles(DGPs) possess the capability of deep profile control and flooding. However, the deep migration behavior and plugging mechanism along their path remain unclear. Breakage, an inevitable phenomen... Deformable gel particles(DGPs) possess the capability of deep profile control and flooding. However, the deep migration behavior and plugging mechanism along their path remain unclear. Breakage, an inevitable phenomenon during particle migration, significantly impacts the deep plugging effect. Due to the complexity of the process, few studies have been conducted on this subject. In this paper, we conducted DGP flow experiments using a physical model of a multi-point sandpack under various injection rates and particle sizes. Particle size and concentration tests were performed at each measurement point to investigate the transportation behavior of particles in the deep part of the reservoir. The residual resistance coefficient and concentration changes along the porous media were combined to analyze the plugging performance of DGPs. Furthermore, the particle breakage along their path was revealed by analyzing the changes in particle size along the way. A mathematical model of breakage and concentration changes along the path was established. The results showed that the passage after breakage is a significant migration behavior of particles in porous media. The particles were reduced to less than half of their initial size at the front of the porous media. Breakage is an essential reason for the continuous decreases in particle concentration, size, and residual resistance coefficient. However, the particles can remain in porous media after breakage and play a significant role in deep plugging. Higher injection rates or larger particle sizes resulted in faster breakage along the injection direction, higher degrees of breakage, and faster decreases in residual resistance coefficient along the path. These conditions also led to a weaker deep plugging ability. Smaller particles were more evenly retained along the path, but more particles flowed out of the porous media, resulting in a poor deep plugging effect. The particle size is a function of particle size before injection, transport distance, and different injection parameters(injection rate or the diameter ratio of DGP to throat). Likewise, the particle concentration is a function of initial concentration, transport distance, and different injection parameters. These models can be utilized to optimize particle injection parameters, thereby achieving the goal of fine-tuning oil displacement. 展开更多
关键词 Physical simulation Deformable gel particle BREAKAGE particle size Residual resistance coefficient
下载PDF
Particle size characterization and sources of sediments in the Uzhumqin sand dunes
8
作者 ZHANG Hao LIU Yang +3 位作者 DANG Xiaohong MENG Zhongju LI Shuangli GAO Yong 《Journal of Mountain Science》 SCIE CSCD 2024年第8期2631-2645,共15页
Sediment constitutes the fundamental basis for forming and evolving aeolian geomorphology.The characteristics of sediment particle size offer insights into the development and evolution of sandy terrain,making their s... Sediment constitutes the fundamental basis for forming and evolving aeolian geomorphology.The characteristics of sediment particle size offer insights into the development and evolution of sandy terrain,making their study critical to understanding aeolian geomorphology and sand control.In this study,we combined high-density collection of surface sediments in the Uzhumqin sand dunes and GIS spatial analysis to analyze the particle size parameters and changes in the spatial distribution of surface sediments in this region.In addition,we used an end-member analysis to identify the potential sources of the sediments.The results showed that surface sediments in the Uzhumqin sand dunes had distinct spatial distributions.Medium and coarse grain sands dominated the sediments in the dunes,and the mean grain size and the sorting coefficient generally increased along the prevailing wind direction,with high values in individual areas related to factors such as material sources and vegetation cover.Skewness was strongly influenced by factors such as landform change and human activity,and spatial variability became more complex.Kurtosis and the soil fractal dimension showed generally decreasing trends along the prevailing wind direction.With dune fixation,the contents of clay and powder particles in the soil increased;the mean particle size,the sorting coefficient,and the fractal dimension of the soil gradually increased,and the skewness and kurtosis gradually decreased.The end-member analysis results indicated the existence of five end-members(EM)in the dune sediments.EM 1 was a mixed component of wind-deposited fine sands and nearby fluvial sediments.EM 2 was the main component of sediments in the study area and was the result of sorting lake sediments by wind action and by the local topography.EM 3 may be a product of river flood deposition.EM 4 and EM 5 had coarser grain sizes.EM 4 was a lake-phase sediment product influenced by topographic and vegetation cover factors,and EM 5 was primarily a river and lake sediment product modified by weathering.The sediment particle size results from the study area indicate that the sediment in the sandy region is generally coarse due to multiple factors,including topography,climate,hydrology,and human activity.Sandy material in the study area originated from nearby,with very little sand being transported from long distances. 展开更多
关键词 SEDIMENT particle size Spatial differences End-member analysis Uzhumqin sand dunes
下载PDF
Extended wet sieving method for determination of complete particle size distribution of general soils
9
作者 Shengnan Ma Yi Song +2 位作者 Jiawei Liu Xingyu Kang Zhongqi Quentin Yue 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第1期242-257,共16页
The traditional standard wet sieving method uses steel sieves with aperture?0.063 mm and can only determine the particle size distribution(PSD)of gravel and sand in general soil.This paper extends the traditional meth... The traditional standard wet sieving method uses steel sieves with aperture?0.063 mm and can only determine the particle size distribution(PSD)of gravel and sand in general soil.This paper extends the traditional method and presents an extended wet sieving method.The extended method uses both the steel sieves and the nylon filter cloth sieves.The apertures of the cloth sieves are smaller than 0.063 mm and equal 0.048 mm,0.038 mm,0.014 mm,0.012 mm,0.0063 mm,0.004 mm,0.003 mm,0.002 mm,and 0.001 mm,respectively.The extended method uses five steps to separate the general soil into many material sub-groups of gravel,sand,silt and clay with known particle size ranges.The complete PSD of the general soil is then calculated from the dry masses of the individual material sub-groups.The extended method is demonstrated with a general soil of completely decomposed granite(CDG)in Hong Kong,China.The silt and clay materials with different particle size ranges are further examined,checked and verified using stereomicroscopic observation,physical and chemical property tests.The results further confirm the correctness of the extended wet sieving method. 展开更多
关键词 particle size distribution(PSD) General soil SILT CLAY Wet sieving Physical and chemical properties
下载PDF
High-Volume Mineral Admixtures Cement: The Effects of Particle Size Distribution
10
作者 黄启珉 WANG Kun +3 位作者 LU Jiping YU Jianping SHENG Zhenhua 杨露 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第1期102-108,共7页
The effects of high-volume slag-fly ash cement with different particle sizes on hydration degree,microstructure and mechanical properties were systematically studied,by means of laser particle size(DLS),X-ray diffract... The effects of high-volume slag-fly ash cement with different particle sizes on hydration degree,microstructure and mechanical properties were systematically studied,by means of laser particle size(DLS),X-ray diffraction (XRD),comprehensive thermal analysis (TG-DTA),scanning electron microscopy(SEM) and mechanical properties tests.The results show that suitable particle size distribution of cementitious material has significantly promoting effects on hydration reaction rate and mechanical properties.Compared with slag without further grinding,the slag after ball milling for 4 h has an obvious improvement in reactivity,which also provides a faster hydration rate and higher compressive strength for the cementitious material.When the slag milled for 1 and 4 h is mixed at a mass ratio of 2:1 (i e,slag with D_(50) of 7.4μm and average size of 9.9μm,and slag with D_(50) value of 2.6μm and average size of 5.3μm),and a certain amount of fly ash is added in,the most obvious improvement of compressive strength of cement is achieved. 展开更多
关键词 ultrafine slag MICROSTRUCTURE compressive strength particle size
下载PDF
Particle size spatial distribution in landslide dams
11
作者 ZHANG Jingyi ZHANG Jianmin 《Journal of Mountain Science》 SCIE CSCD 2024年第6期1886-1903,共18页
The particle composition and spatial distribution of landslide-induced dam bodies are critical geotechnical parameters for studying the hazards of dam-break floods.However,current research often neglects the influence... The particle composition and spatial distribution of landslide-induced dam bodies are critical geotechnical parameters for studying the hazards of dam-break floods.However,current research often neglects the influence of the initial particle composition and spatial distribution of the landslide on the particle composition and spatial distribution of the landslide dam.This study investigated the impact of initial particle size distribution,volume,and sliding length on the energy and velocity changes of characteristic particles during the sliding process and the spatial distribution of particle sizes in the landslide dam body.Numerical simulations and physical models were employed to examine the effects of sequential gradient arrangements(where particle sizes decrease from top to bottom)and four other different initial particle arrangements on the energy and velocity changes of particles and the spatial distribution of particle sizes in the dam body.The study reveals the characteristics of translational and rotational energy of different particles and the laws of mechanical energy conversion,obtaining the spatial distribution patterns of particle sizes in landslide-induced dams.The results show that under the sequential gradient arrangement,the energy dissipation of the landslide movement is lower,with larger particles mainly distributed at the distal end and smaller particles at the proximal end of the landslide dam.In contrast,under the reverse gradient arrangement,the energy dissipation of the landslide movement is higher,and the distribution pattern of the dam particles is opposite to that of the sequential gradient arrangement.For the other arrangement modes,the spatial distribution of dam particles falls between the aforementioned two.There is a positive correlation between particle size and translational kinetic energy within the particle flow during the landslide process,and rotational motion increases energy dissipation.Under constant slope conditions,sliding length does not affect the movement pattern of the particle flow or the spatial distribution of particles in the dam body.The findings of this study provide a scientific basis for the accurate simulation and prediction of dam-break flood processes. 展开更多
关键词 particle size distribution LANDSLIDE Numerical simulation Discrete element method
下载PDF
A real-time and modular approach for quick detection and mechanism exploration of DPIs with different carrier particle sizes 被引量:1
12
作者 Yingtong Cui Ying Huang +8 位作者 Xuejuan Zhang Xiangyun Lu Jun Xue Guanlin Wang Ping Hu Xiao Yue Ziyu Zhao Xin Pan Chuanbin Wu 《Acta Pharmaceutica Sinica B》 SCIE CAS CSCD 2022年第1期437-450,共14页
Dry powder inhalers(DPIs) had been widely used in lung diseases on account of direct pulmonary delivery, good drug stability and satisfactory patient compliance. However, an indistinct understanding of pulmonary deliv... Dry powder inhalers(DPIs) had been widely used in lung diseases on account of direct pulmonary delivery, good drug stability and satisfactory patient compliance. However, an indistinct understanding of pulmonary delivery processes(PDPs) hindered the development of DPIs. Most current evaluation methods explored the PDPs with over-simplified models, leading to uncompleted investigations of the whole or partial PDPs. In the present research, an innovative modular process analysis platform(MPAP) was applied to investigate the detailed mechanisms of each PDP of DPIs with different carrier particle sizes(CPS). The MPAP was composed of a laser particle size analyzer, an inhaler device,an artificial throat and a pre-separator, to investigate the fluidization and dispersion, transportation,detachment and deposition process of DPIs. The release profiles of drug, drug aggregation and carrier were monitored in real-time. The influence of CPS on PDPs and corresponding mechanisms were explored. The powder properties of the carriers were investigated by the optical profiler and Freeman Technology four powder rheometer. The next generation impactor was employed to explore the aerosolization performance of DPIs. The novel MPAP was successfully applied in exploring the comprehensive mechanism of PDPs, which had enormous potential to be used to investigate and develop DPIs. 展开更多
关键词 Dry powder inhaler Carrier particle size Pulmonary delivery process Real-time monitor Quick detection
原文传递
Creating burdock polysaccharide-oleanolic acid-ursolic acid nanoparticles to deliver enhanced anti-inflammatory effects:fabrication,structural characterization and property evaluation 被引量:3
13
作者 Shanshan Zhu Zhichang Qiu +5 位作者 Xuguang Qiao Geoffrey I.N.Waterhouse Wenqing Zhu Wenting Zhao Qiuxia He Zhenjia Zheng 《Food Science and Human Wellness》 SCIE CSCD 2023年第2期454-466,共13页
This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encaps... This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encapsulating OA+UA with ALPs(ALP:OA+UA,50:1;OA:UA,1:1)changed the crystalline nature to a more amorphous state through hydrogen bonding and involving O-H/C-O/O-C-O groups.ALP-OA/UA nanoparticles had a particle size and zeta potential(in water)of 199.1 nm/-7.15 mV,with a narrow unimodal size distribution,and excellent pH,salt solution,temperature and storage stability.Compared with ALPs,ALPOA/UA nanoparticles showed enhanced anti-inflammatory activity(especially at a dose of 100μg/mL)in a CuSO-induced zebrafish inflammation model via down-regulating the NF-κB signalling pathway and gene expression of associated transcription factors and cytokines(TNF-α,IL-1βand IL-8).Therefore,ALP-based nanoparticles are natural and anti-inflammatory carriers for hydrophobic bioactive molecules. 展开更多
关键词 ENCAPSULATION Structural features particle size Zeta potential Thermodynamic properties In vivo verification
下载PDF
On the critical particle size of soil with clogging potential in shield tunneling 被引量:3
14
作者 Shuying Wang Zihao Zhou +3 位作者 Pengfei Liu Zhao Yang Qiujing Pan Weizhong Chen 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第2期477-485,共9页
Shield tunneling is easily obstructed by clogging in clayey strata with small soil particles.However,soil clogging rarely occurs in strata with coarse-grained soils.Theoretically,a critical particle size of soils shou... Shield tunneling is easily obstructed by clogging in clayey strata with small soil particles.However,soil clogging rarely occurs in strata with coarse-grained soils.Theoretically,a critical particle size of soils should exist,below which there is a high risk of soil clogging in shield tunneling.To determine the critical particle size,a series of laboratory tests was carried out with a large-scale rotary shear apparatus to measure the tangential adhesion strength of soils with different particle sizes and water contents.It was found that the tangential adhesion strength at the soilesteel interface gradually increased linearly with applied normal pressure.When the particle size of the soil specimen was less than 0.15 mm,the interfacial adhesion force first increased and then decreased as the water content gradually increased;otherwise,the soil specimens did not manifest any interfacial adhesion force.The amount of soil mass adhering to the steel disc was positively correlated with the interfacial adhesion force,thus the interfacial adhesion force was adopted to characterize the soil clogging risk in shield tunneling.The critical particle size of soils causing clogging was determined to be 0.15 mm.Finally,the generation mechanism of interfacial adhesion force was explored for soils with different particle sizes to explain the critical particle size of soil with clogging risk in shield tunneling. 展开更多
关键词 Shield tunneling Soil clogging ADHESION Critical particle size
下载PDF
Effect of particle size of single-crystalline hierarchical ZSM-5 on its surface mass transfer in n-heptane catalytic cracking 被引量:2
15
作者 Xiaoxue Zhang Shuman Xu +3 位作者 Jing Hao Xiaojin Xie Fengqiu Chen Dangguo Cheng 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第11期148-157,共10页
Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-h... Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-heptane catalytic cracking reaction.Diffusional measurements by zero-length column(ZLC)method showed that the apparent diffusivities of n-heptane decreased with the reduction of particle size,indicating the existence of surface barriers.Moreover,with the decrease of particle size,the additional diffusion path length increased,which meant the influence of surface barriers became more apparent.Despite the change of surface barriers,the intracrystalline diffusion still dominated the overall diffusion.Catalytic performance showed that the zeolite with smaller particle size had better stability. 展开更多
关键词 SINGLE-CRYSTALLINE Hierarchical ZSM-5 particle size Surface barriers n-Heptane catalytic cracking
下载PDF
The type of lipid supplement has crucial implications for forage particle size in calf starter diets
16
作者 Pedram Panahiha Hamidreza Mirzaei‑Alamouti +3 位作者 Mehdi Kazemi‑Bonchenari Mehdi Poorhamdollah Mina Vazirigohar Jorg R.Aschenbach 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2023年第6期2525-2538,共14页
Background Forage inclusion in starters of young dairy calves has become an acceptable strategy in the last decade.To compensate for the lower energy provided by forage,concurrent lipid supplementation can be proposed... Background Forage inclusion in starters of young dairy calves has become an acceptable strategy in the last decade.To compensate for the lower energy provided by forage,concurrent lipid supplementation can be proposed.How-ever,ruminal microbial activity and forage digestibility may be decreased by lipid supplementation.We hypothesized that the composite effect of forage and lipid supplements may be dependent on forage particle size and the type of lipid supplement.Therefore,we evaluated the effect of long(LP;geometric mean,4.97 mm)vs.short alfalfa hay particle sizes(SP;geometric mean,1.26 mm)with either soybean oil(SBO)or palm fatty acids(PLF)as lipid source in a 2×2 factorial design with treatments SP-SBO,SP-PLF,LP-SBO,and LP-PLF.Treatments(n=13 with 6 males and 7 females each)were offered to Holstein calves(3 days old)with equal amounts of lipid(25 g/kg DM)through-out the experimental period.The milk offering scheme(d 1 to 53)was equal for all groups.Data collection continued until 20 d post-weaning.Results Interaction between forage particle size and lipid supplement was significant for the following readouts:the highest and lowest starter intakes during the pre-weaning period occurred in LP-PLF and LP-SBO,respectively.This was associated with similarly contrasting changes in average daily gain(ADG)during the post-weaning period,body weight at the end of experiment,withers height,digestibility of organic matter and neutral detergent fiber,and blood serum concentrations of glucose,beta-hydroxybutyrate,and insulin during the pre-weaning period.Dur-ing both pre-and post-weaning periods,the highest and lowest urinary excretion of allantoin and total purine deriva-tives,representing microbial protein synthesis,were observed in LP-PLF and LP-SBO,respectively,indicating that those diets were most and least favorable for rumen development.Irrespective of forage particle size,supplemental SBO vs.PLF increased serum malondialdehyde as an oxidative stress indicator across periods,increased blood urea nitrogen and feed efficiency in the pre-weaning period,and reduced hip height during the post-weaning period.Conclusions It can be concluded that feeding a rumen-inert,mostly saturated fatty acid source with alfalfa hay as long particle size is recommended with view on performance,whereas a combination soybean oil rich in unsatu-rated fatty acids should not be provided to milk-fed Holstein calves together with long particle forage.Feeding soybean oil and alfalfa hay as long particles is not advisable mainly due to lower starter consumption and impaired development of ruminal function.If dietary supplementation of soybean oil is applied,incorporation of forage as small particles should be preferred to support rumen development. 展开更多
关键词 Forage particle size Lipid supplement Oxidative stress Ruminal functional development
下载PDF
The Effects of the Particle Size Ratio on the Behaviors of Binary Granular Materials
17
作者 Deze Yang Xihua Chu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第7期63-85,共23页
The particle size ratio(PSR)is an important parameter for binary granular materials,which may aect the microstructure and macro behaviors of granular materials.However,the eect of particle ratio on granular assembli... The particle size ratio(PSR)is an important parameter for binary granular materials,which may aect the microstructure and macro behaviors of granular materials.However,the eect of particle ratio on granular assemblies with dierent arrangements is still unclear.To explore and further clarify the eect of PSR in dierent packing structures,three types of numerical samples with regular,layered,and random packing are designed.Numerical results show that PSR has signi􀀀cant eects on binary granular samples with regular packing.The larger the PSR,the stronger the strength,the larger the modulus,and the smaller the angle between the shear band and the load direction.And a theoretical solution of the peak stress ratio vs.PSR is obtained for regular packing,and the results by DEM are in good agreement with the theoretical solution.Under layered packing,PSR has little eect on peak stress ratio due to similar microstructure obtained with the changing of PSR.The modulus slightly increased with the increase of PSR.Under random packing with small grain content of 50%,PSR has little eect in the range of 0.5–0.9,but in a larger range,larger PSR leads to greater modulus. 展开更多
关键词 Discrete element method binary granular materials particle size ratio PACKING
下载PDF
An image segmentation method of pulverized coal for particle size analysis
18
作者 Xin Li Shiyin Li +3 位作者 Liang Dong Shuxian Su Xiaojuan Hu Zhaolin Lu 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第9期1181-1192,共12页
An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image s... An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image segmentation.However,the agglomeration effect of fine powders and the edge effect of granular images caused by scanning electron microscopy greatly affect the precision of particle image segmentation.In this study,we propose a novel image segmentation method derived from mask regional convolutional neural network based on deep learning for recognizing fine coal powders.Firstly,an atrous convolution is introduced into our network to learn the image feature of multi-sized powders,which can reduce the missing segmentation of small-sized agglomerated particles.Then,a new mask loss function combing focal loss and dice coefficient is used to overcome the false segmentation caused by the edge effect.The final comparative experimental results show that our method achieves the best results of 94.43%and 91.44%on AP50 and AP75 respectively among the comparison algorithms.In addition,in order to provide an effective method for particle size analysis of coal particles,we study the particle size distribution of coal powders based on the proposed image segmentation method and obtain a good curve relationship between cumulative mass fraction and particle size. 展开更多
关键词 Pulverized coal Image segmentation Deep learning particle size analysis
下载PDF
Deflagration characteristics of freely propagating flames in magnesium hydride dust clouds 被引量:1
19
作者 Qiwei Zhang Yangfan Cheng +2 位作者 Beibei Zhang Danyi Li Zhaowu Shen 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第1期471-483,共13页
The flame propagation processes of MgH_(2)dust clouds with four different particle sizes were recorded by a high-speed camera.The dynamic flame temperature distributions of MgH_(2)dust clouds were reconstructed by the... The flame propagation processes of MgH_(2)dust clouds with four different particle sizes were recorded by a high-speed camera.The dynamic flame temperature distributions of MgH_(2)dust clouds were reconstructed by the two-color pyrometer technique,and the chemical composition of solid combustion residues were analyzed.The experimental results showed that the average flame propagation velocities of 23μm,40μm,60μm and 103μm MgH_(2)dust clouds in the stable propagation stage were 3.7 m/s,2.8 m/s,2.1 m/s and 0.9 m/s,respectively.The dust clouds with smaller particle sizes had faster flame propagation velocity and stronger oscillation intensity,and their flame temperature distributions were more even and the temperature gradients were smaller.The flame structures of MgH_(2)dust clouds were significantly affected by the particle sinking velocity,and the combustion processes were accompanied by micro-explosion of particles.The falling velocities of 23μm and 40μm MgH_(2)particles were 2.24 cm/s and 6.71 cm/s,respectively.While the falling velocities of 60μm and 103μm MgH_(2)particles were as high as 15.07 cm/s and 44.42 cm/s,respectively,leading to a more rapid downward development and irregular shape of the flame.Furthermore,the dehydrogenation reaction had a significant effect on the combustion performance of MgH_(2)dust.The combustion of H_(2)enhanced the ignition and combustion characteristics of MgH_(2)dust,resulting in a much higher explosion power than the pure Mg dust.The micro-structure characteristics and combustion residues composition analysis of MgH_(2)dust indicated that the combustion control mechanism of MgH_(2)dust flame was mainly the heterogeneous reaction,which was affected by the dehydrogenation reaction. 展开更多
关键词 Magnesium hydride dust Flame combustion mechanism particle size Dust explosion Two-color pyrometer
下载PDF
Particle modulations to turbulence in two-phase round jets 被引量:1
20
作者 Bing Wang Huiqiang Zhang Yi Liu Xiaofen Yan Xilin Wang School of Aerospace, Tsinghua University, 100084 Beijing, China 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2009年第5期611-617,共7页
The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer (PDA). Laden with very large particles, no significant atten... The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer (PDA). Laden with very large particles, no significant attenuations of turbulence intensities were measured in the farfields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle prop- erties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity. 展开更多
关键词 particle modulations Turbulence intensity particle sizes Two-phase slip velocity particle-laden round turbulent jet
下载PDF
上一页 1 2 22 下一页 到第
使用帮助 返回顶部