检索结果-南通市图书馆

EFFECTS OF GAS TYPE AND TEMPERATURE ON FINE PARTICLE FLUIDIZATION

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Particuology 2006年第3期4卷 114-121页

作者： Chunbao x. J.-x. zhu Department of Chemical Engineering Lakehead University Thunder Bay Ontario P7B 5E1 Canada powder Technology Research Centre Department of Chemical & Biochemical Engineering The University of Western Ontario London Ontario N6A 5B9 Canada

The influence of gas type （helium and argon） and bed temperature （77-473 K） on the fluidization behaviour of Geldart groups C and A particles was investigated. For both types of particles tested, i.e., Al2O3 （4.8μm） and glass beads （39 μm）, the fluidization quality in different gases shows the following priority sequence： Ar 〉 He. In the same gaseous atmosphere, the particles when fluidized at an elevated temperature usually show larger bed voidages, higher bed pressure drops, and a lower Umf for the group A powder, all indicating an enhancement in fluidization quality. Possible mechanisms governing the operations of gas type and temperature in influencing the fluidization behaviours of fine particles have been discussed with respect to the changes in both gas properties and interparticle forces （on the basis of the London-van der Waals theory）. Gas viscosity （varying significantly with gas-type and temperature） proves to be the key parameter that influences the bed pressure drops and Umf in fluidization of fine particles, while the interparticle forces （also varying with gas-type and temperature） may play an important role in fine-particle fluidization by affecting the ex.ansion behaviour of the particle-bed.

关键词： fluidization fine particles gas type temperature interparticle forces

GAS-SOLIDS FLOW BEHAVIOR WITH A GAS VELOCITY CLOSE TO ZERO

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Particuology 2006年第3期4卷 167-177页

作者： H. Zhang J.-x. zhu Department of Chemical Engineering University of Western Ontario London Ontario Canada N6A 5B9 Canada

In a 9.3 m high and 0.10 m i.d. gas-solids downflow fluidized bed （downer）, the radial and ax.al distributions of the local solids holdups and particle velocities along the downer column were measured with the superficial gas velocity set to zero. A unique gas-solids flow structure was found in the downer system with zero gas velocity, which is completely different from that under conditions with higher gas velocities, in terms of its radial and ax.al flow structures as well as its micro flow structure. The gas-solids flow pattern under zero gas velocity conditions, together with that under low gas velocity conditions, can be considered as a special regime which differs from that under higher gas velocity conditions. According to the hydrodynamic properties of the two regimes, they can be named the ＂dense annulus＂ regime for the flow pattern under zero or low gas velocity conditions and the ＂dense core＂ regime for that under higher gas velocity conditions.

关键词： downer reactor gas-solids cocurrent downflow fluidized bed hydrodynamics flow development particle velocity solids holdup solids flux flow regime

Fractional contribution of store-released Ca2+ to cytosolic Ca2+ rise following TRPA1 activation in mouse dorsal root ganglion neurons

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fractional contribution of store-released Ca2+ to cytosolic ...

INITIATION AND DEVELOPMENT PROCESSES OF TUNNEL SYSTEMS IN THE HILLY LOESS REGION OF NORTHERN CHINA

中国生理学会第九届全国青年生理学工作者学术会议

作者： Mike x. zhu Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston

Transient receptor potential A1(TRPA1) is a nonselective cation channel implicated in thermosensation and ***1 is activated by a broad spectrum of environmental *** we show that TRPA1 activation permits Ca-influx.through both plasma membrane and intracellular Ca-stores in mouse dorsal root ganglion(DRG) *** Ca influx.through TRPA1 channels in the plasma membrane failed to fully block the intracellular Ca rise,indicating a contribution of internal Ca *** fractional contribution of store Ca release activated by TRPA1(P) was 40%of the overall intracellular Ca rise,which was much larger than that activated via TRPV1(P= 9%).Intracellular Ca rise following TRPA1 activation triggered vesicle ***,in native DRG neurons,functional TRPA1 channels are present both on the plasma membrane and internal Ca stores,with the internal store Ca release contributing to a rather large fraction of the overall TRPA1-elicted Ca signal.

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2006年第3期21卷 171-179页

作者： T. x. zhu1 Dr., Department of Geography, University of Minnesota-Duluth, 10 University Dr., Duluth, MN 55812, U.S.A. Department of Geography University of Minnesota-Duluth MN 55812 United States

Tunnel systems in the hilly loess region of northern China are among the largest and most complicated in the world. Tunnel formation and development processes were investigated in the Yangdaogou catchment over the period of 1989 through 2002. Newly formed tunnels on the roads in the Wangjiagou watershed were also ex.mined in detail during a single storm in 2002. Soil samples were taken from various locations of the tunnel systems in the Yangdaogou catchment for chemical and physical analyses. The controlling factors of tunnel formation are surface drainage conditions and soil materials. Rapid downward mechanical erosion by storm flows seems to be responsible for the original formation of inlets. All tunnels are found in loess and none was found in red Tertiary earth. Underground tunnel paths often develop right above an impeding layer, mainly resulting from mechanical erosion rather than chemical dissolution. New inlets develop in old tunnel systems in two major ways. One is roof collapses of an ex.sting tunnel path and the other is the mechanical scouring action of storm flows. A tunnel system can ex.and upslope or downslope but the associated processes differ. Upslope ex.ansion often starts with the formation of one or more inlets resulting from surface washes, followed by the development of an underground tunnel path. Downslope development of a tunnel system is characterized by uneven enlargement of tunnel paths. This study suggests that the key to control of tunnel development is reducing surface water entering a tunnel.

关键词： Piping Tunnel erosion Semi-arid areas Gully erosion Loess Plateau

TiS2-based saturable absorber for ultrafast fiber lasers

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Photonics Research 2018年第10期6卷 I0046-I0050页

作者： x. zhu S. CHEN M. ZHANG L. CHEN Q. Wu J. ZHAO Q．JIANG Z．ZHENG H．ZHANG School of Electronic and Information Engineering Beihang University Beijing 100191 China Department of Optoelectronics Engineering Shenzhen University Shenzhen 518060 China College of Health Science and Environmental Engineering Shenzhen Technology University Shenzhen 518118 China College of Materials Science and Engineering Shenzhen University Shenzhen 518060 China

We fabricate titanium disulfide(TiS2) using a liquid ex.oliation method and subsequently a TiS2-based device by optically depositing the TiS2 material onto the microfiber. This device ex.ibits a strong nonlinear saturable absorption property with an optical modulation depth of 8.3% at 1560 nm. With the implementation of this all-fiber TiS2-based saturable absorber, we demonstrate that both mode-locking and Q-switching operation can be obtained in a turn-key all-fiber erbium-doped laser cavity. Our findings constitute the first ex.mple, to the best of our knowledge, of a TiS2-based saturable absorber for ultrashort pulse generation and highlight the great potential of such devices in two-dimensional nanomaterials-related photonics.

关键词：液体剥离方法激光器通讯技术发展现状

维普期刊数据库

ANALYSIS OF THE CHAOTIC DYNAMICS OF A HIGH-FLUx.CFB RISER USING SOLIDS CONCENTRATION MEASUREMENTS

在线全文

学校读者我要写书评

暂无评论

China Particuology 2006年第3期4卷 136-146页

作者： S. V. Manyele J.-x. zhu R. E. Khayat J. H. Parssinen Department of Chemical and Biochemical Engineering University of Western Ontario London ON N6A 5B9 Canada Department of Mechanical and Materials Engineering University of Western Ontario London ON N6A 5B9 Canada

A high-flux.circulating fluidized bed （CFB） riser （0.076-m I.D. and 10-m high） was operated in a wide range of operating conditions to study its chaotic dynamics, using FCC catalyst particles （dp= 67μm, ρp = 1500 kg·m^-3）. Local solids concentration fluctuations measured using a reflective-type fiber optic probe were processed to determine chaotic invariants （Kolmogorov entropy and correlation dimension）, Radial and ax.al profiles of the chaotic invariants at different operating conditions show that the core region ex.ibits higher values of the chaotic invariants than the wall region. Both invariants vary strongly with local mean solids concentration. The transition section of the riser ex.ibits more complex.dynamics while the bottom and top sections ex.ibit a more uniform macroscopic and less-complex.microscopic flow structure. Increasing gas velocity leads to more complex.and less predictable solids concentration fluctuations, while increasing solids flux.generally lowers complex.ty and increases predictability. Very high solids flux. however, was observed to increase the entropy.

关键词： high-flux.riser, concentration fiber optic probe, chaos analysis correlation dimension, Kolmogorov entropy

维普期刊数据库

GAS-SOLIDS FLOW BEHAVIOR WITH A GAS VELOCITY CLOSE TO ZERO

在线全文

学校读者我要写书评

暂无评论

Particuology 2006年第Z1期 167-177页

作者： H. Zhang and J.-x. zhu* Department of Chemical Engineering, University of Western Ontario, London, Ontario, Canada N6A 5B9, Canada

In a 9.3 m high and 0.10 m i.d. gas-solids downflow fluidized bed (downer), the radial and ax.al distribu- tions of the local solids holdups and particle velocities along the downer column were measured with the superficial gas velocity set to zero. A unique gas-solids flow structure was found in the downer system with zero gas velocity, which is completely different from that under conditions with higher gas velocities, in terms of its radial and ax.al flow structures as well as its micro flow structure. The gas-solids flow pattern under zero gas velocity conditions, together with that under low gas velocity conditions, can be considered as a special regime which differs from that under higher gas velocity conditions. According to the hydrodynamic properties of the two regimes, they can be named the “dense annulus” regime for the flow pattern under zero or low gas velocity conditions and the “dense core” regime for that under higher gas ve- locity conditions.

关键词： downer reactor gas-solids cocurrent downflow fluidized bed hydrodynamics flow development particle velocity solids holdup solids flux flow regime

Analysis of Flow Dynamics in the High-Flux.Gas-Solid Riser Using Trajectory Distances across Attractors Reconstructed from Solid Concentration Signals

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Engineering（科研） 2018年第10期10卷 688-703页

作者： Justin M. Jeremiah Samwel V. Manyele Abraham K. Temu Jesse-x. zhu Department of Chemical and Mining Engineering University of Dar es Salaam Dar es Salaam Tanzania Department of Chemical and Biochemical Engineering University of Western Ontario London ON Canada

The study of the entrance and wall dynamics of a high-flux.gas-solid riser was conducted using trajectory distances of the reconstructed attractors from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analyzed using codes prepared in FORTRAN 2008 to get trajectories of the reconstructed attractors and their distances apart. Trajectory distances were found to increase from the centre towards the wall indicating the ex.ansion of the attractor. The probability density function (PDF) of the trajectory distances changes from single peak at the centre to multiple peaked profiles in the wall region. Multiple peaked profiles indicate multifractal flow behaviours. Cumulative distribution functions (CDF) of the trajectory distances changes from single S-shaped at the centre to multiple S-shaped profiles in some locations of the wall region indicating multifractal flow behaviours. The PDF distribution of these distances at the entrance section and in the wall region forms different types of statistical distributions showing differences in gas-solid flow structures in various spatial locations of the wall region and the entrance sections. Most of the distributions at the centre fall under the Gumbel max.distribution for all flow development sections of the riser, especially at air velocities of 5.5 m/s and 8 m/s showing uniform flow structures. Further, it was found that increase of the number of the phase space reconstruction embedding dimension increases the trajectory distances between the state vectors leading to the ex.ansion of the attractor.

关键词： Trajectory Distance Probability Density Function Cumulative Distribution Function Euclidian Distance High-Flux Riser

Investigation of Entrance and Wall Dynamics of the High-Flux.Gas-Solid Riser Using Statistical Analysis of Solids Concentration Signals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Engineering（科研） 2019年第3期11卷 167-187页

Statistical analysis of the entrance and wall dynamics of a high-flux.gas-solid riser was done using solid concentration time series data collected from a 76 mm internal diameter and 10 m high riser of a CFB system with a twin-riser operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analysed using code prepared using FORTRAN 2008 to get statistical parameters and plot their profiles. Results obtained show that the gas-solid suspension flow in the riser is dominated by low solid concentration in the centre region and high solid concentration in the wall region which forms a core-annulus flow structure. The mean solid concentration in the wall region decreases with riser height from the dense bottom section to less dense in the fully developed flow section at the top of the riser. The gas-solid suspension flow in the centre region is dominated with uniform flow structure while the wall region is dominated with high fluctuations in solid concentration. Further, it was found that the entrance and developing flow sections of the riser ex.ibit high flow non-uniformities than the fully developed flow section of the riser. The flow non-uniformities in the entrance and developing flow section increase with increase in superficial gas velocity at constant solid flux. The wall region, from the entrance to the top sections of the riser along the ax.al direction ex.ibits both dilute and dense suspension flow.

关键词： Entrance Section Wall Region Statistical Analysis Flow Non-Uniformities Radial Non-Uniformity Index