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EFFECTS OF GAS TYPE AND TEMPERATURE ON FINE PARTICLE FLUIDIZATION

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

作者： Chunbao Xu 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 expansion behaviour of the particle-bed.

关键词： fluidization fine particles gas type temperature interparticle forces

EFFECTS OF TREATMENT TIME ON CORROSION OF DIFFUSION-ALLOYED COATINGS OF PURE MAGNESIUM

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Acta Metallurgica Sinica(English Letters) 2007年第1期20卷 72-78页

作者： Y.P. Ma j. Li j. zhu L. Yang Y.G. Liu Z.Y. Li F. Zhao School of Metallurgic Engineering Xi＇an University of Architecture ＆ Technology Xi＇an 710055 China

The corrosion resistance of pure magnesium with surface alloying layer obtained by a solid diffusion alloying technique has been analyzed. To establish the optimum treatment time, the experiments were performed at 480℃ for different solid diffusion time （8, 16, and 24h）. The diffusion interaction effectiveness between Zn, Al mix powder and the sample surface, depending on the treatment time for diffusion at given temperatures, has an obvious influence on corrosion resistance and corrosion mechanism. Corrosion properties were studied using the constant immersion test （in 3.0% NaCl solution, temperature is （28±1）℃, and time is 96h）. Optical microscopy （OM） and EDS （energy dispersive spectrum） composition analysis were used to examine the cross-sectional microstructural characteristics of alloyed layer of treated samples. It is shown that in comparison with the untreated samples, the treated ones possess a better corrosion resistance. The Al5Mg11Zn4 phase, which formed as a continuous phase due to the diffusion of Al, Zn, and Mg elements and subsequent interaction on the outermost layer of diffusion alloying zones （especially the samples treated for 24h at 480℃）, was inert to the chloride solution compared with pure magnesium and acted as a corrosion barrier, and therefore the best corrosion resistance was obtained. This protective action of Al5Mg11Zn4 phase was found to change with its amount, which was controlled by the diffusion time at given temperature. It was concluded that the continuous Al5Mg11Zn4 phase （WP-zone） of the reacted layer in pure magnesium was beneficial from the point of view of corrosion resistance.

关键词： pure magnesium solid diffusion treatment time microstructure corrosion

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

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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 axial 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 axial 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

Finite Element - Artificial Transmitting Boundary Method for Acoustical Field on Tapered Waveguide

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光学学报 2003年第S1期23卷 167-168页

作者： j. S. Yang G F. Fan j. P. zhu C.K. Sun Y. H. zhu Department of Applied Physics Tianjin University P.R.ChinaDepartment of Applied Physics Tianjin University P.R.ChinaDepartment of Applied Physics Tianjin University P.R.ChinaDepartment of Applied Physics Tianjin University P.R.ChinaDepartment of Applied Physics Tianjin University P.R.China

In earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element -artificial transmitting boundary meth... 详细信息

关键词： for in of AOTF on Artificial Transmitting Boundary Method for Acoustical Field on Tapered Waveguide Finite Element

Characterization of multilayers and their interlayers： applicationto Co-based systems

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Chinese Optics Letters 2013年第13期11卷 137-140页

作者： P. j.nnard Z.-S. Wang j.-T. zhu C. Meny j.-M. Andre M.-H. Hu K. Le Guen Laboratoire de Chimie Physique-Matiere Rayonnement UPMC Univ Paris 06 CNRS UMR 7614 11 rue Pierre et Maxie Curie F-75231 Paris cedex 05 France MOE Key Laboratory of Advanced Micro-Structured Materials Institute of PrecisionOptical Engineering Department of Physics Tongji University Shanghai 200092 China Institut de Physique et Chimie des Materiaux de Strasbourg CNRS UMR 7504 23 rue du Loess BP 43 F-67034 Strasbourg cedex 2 France

We use complementary analysis techniques to determine the structure of nanometric periodic multilayers and particularly their interfaces. We focus on Co-based multilayer which can be used as efficient optical component in the extreme ultraviolet （EUV） range. The samples are characterized using reflectivity measurements in order to determine the thickness and roughness of the various layers, X-ray emission and nuclear magnetic resonance （NMR） spectroscopies to identify the chemical state of the atoms present within the stack and know if they interdiffuse. Results are validated through the use of destructive techniques such as transmission electron microscopy or secondary ion mass spectrometry.

关键词： Multilayers

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

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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 axial profiles of the chaotic invariants at different operating conditions show that the core region exhibits 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 exhibits more complex dynamics while the bottom and top sections exhibit 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 complexity 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

Metrics to Evaluate PET Response to Therapy Based on 3D Analysis

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Open j.urnal of Medical Imaging 2020年第3期10卷 133-142页

作者： Michael L. Goris Hongyun j. zhu Stanford University Stanford CA USA University of Arizona Banner University Tucson AZ USA

The disadvantage of visualizing tomography by slices is that an important attribute of the obj.ct, its volume, is not easily perceived or measured. In oncology this creates a problem, which is addressed here: if early detection and response to treatment are an important prognostic element, then volume is important. The literature has proposed surrogates to volume derived from measures on slices, but geometrically they are not well founded. Actual volume analysis is not complex, and the proposed method applies equally well to organs as to tumors. Volume based measures are more sensitive than individual SUV values, of which the commonly most used is the maximum Standardized Uptake Value (SUVm). If the tumor volume is defined, it can be replaced by the total tumor SUV (SUVt). If the metric for change is the ratio after/(before + after), in the patient population analyzed here, the SUVm metric averages 0.132 for response and 0.662 for progression, the total SUVt range is 0.069 to 0.734. In contrast to SUVt, SUVm is based on a weak sampling method since it is based on the value of a single voxel of more than 10 million.

关键词： Metrics PET Response 3D

Sensing Semantics of RSS Feeds by Fuzzy Matchmaking

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Intelligent Information Management 2010年第2期2卷 110-119页

作者： M.W. Yuan P. j.ang j. zhu X.N. Wang 不详

RSS feeds provide a fast and effective way to publish up-to-date information or renew outdated contents for information subscribers. So far RSS information is mostly managed by content publishers but Internet users have less initiative to choose what they really need. More attention needs to be paid on techniques for user-initiative information discovery from RSS feeds. In this paper, a quantitative semantic matchmaking method for the RSS based applications is proposed. Semantic information is extracted from an RSS feed as numerical vectors and semantic matching can then be conducted quantitatively. Ontology is applied to provide a common-agreed matching basis for the quantitative matchmaking. In order to avoid semantic ambiguity of literal statements from distributed and heterogeneous RSS publishers, fuzzy inference is used to transform an individual-dependent vector into an individual-independent vector. Semantic similarities can be revealed as the result.

关键词： RSS Feeds Matchmaking Multi-Agent Semantics

A Second-Order Image Denoising Model for Contrast Preservation

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1406-1427页

作者： Wei zhu Department of Mathematics University of AlabamaBox 870350TuscaloosaAL35487USA

In this work,we propose a second-order model for image denoising by employing a novel potential function recently developed in zhu(j.Sci Comput 88:46,2021)for the design of a regularization *** to this new second-order derivative based regularizer,the model is able to alleviate the staircase effect and preserve image *** augmented Lagrangian method(ALM)is utilized to minimize the associated functional and convergence analysis is established for the proposed *** experiments are presented to demonstrate the features of the proposed model.

关键词： Image denoising Variational model Image contrast Augmented Lagrangian method(ALM)