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Spherical modification of tungsten oxide powder and its mechanism analysis

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Rare Metals 2015年第3期34卷 183-188页

作者： cong-cong wang Cheng-Chang Jia Peng Gao Guo-Cheng Gai Yu-Fen Yang School of Materials Science and Engineering University of Science and Technology Beijing Powder Technology R&D Group Department of Material Science and EngineeringTsinghua University

Owing to its high production costs, complexity of equipment, and difficulty in controlling parameters, spherical or subglobose tungsten powder preparation method cannot meet the demand of industrial production. Tungstic oxide powder was treated by particle composite system and its effects were studied. Morphologies of par- ticles were investigated by scanning electron microscopy （SEM）. Particle size analysis was carried out and the related mechanism was discussed. The results show that the processing effect is best when the rotational speed is set at 4,000 ***-1 for 15 rain： the powder particles become nearly spherical and their sharp edge angles are rounded off and reshaped. When the processing time is 60 min, the powders smash to pieces because of too much energy inputting. So the test results, such as grain size distribution, can be explained well. Nearly spherical tungsten powder is obtained after reduction at 780 ℃ for 2 h and its flow ability is significantly improved.

关键词： Nearly spherical tungsten powder Grain size Modification Particle composite system

Spherical modification of tungsten powder by particle composite system

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Rare Metals 2022年第6期41卷 1972-1976页

作者： cong-cong wang Cheng-Chang Jia Peng Gao Guo-Sheng Gai Yu-Fen Yang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Powder Technology R&D Group Department of Material Science and EngineeringTsinghua UniversityBeijing 100084China

Owing to contradiction between increasing demand of spherical tungsten powder and limitation of traditional manufacturing technology,a novel preparation method was developed to sphericize the polygonal tungsten powder by means of modification of particle composite *** powder particles were modified by par-ticle composite system,and detailed characterization by scanning electron microscopy(SEM)was *** size distribution and function mechanism were analyzed,and the internal relationship between average diameter and processing time was *** results show that the spherical tungsten powder with an average diameter of 6.41μm is obtained from polyhedral tungsten powder with an average diameter of 7.50μ*** spherical effect could be achieved(sharp edge angles of particles are rounded off and reshaped)when the processing time is over 30 *** relationship between average diameter(d)and pro-cessing time can be described by the exponential decay model,which provides a good interpretation for the process of *** relationship between them can be expressed by the equation d=1.87406exp(-x/8.92718)+*** proposed method could readily enable large-scale production of spherical tungsten powder.

关键词： Tungsten powder Modification Average diameter Powder metallurgy

Dielectric properties of spark plasma sintered AlN/SiC composite ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第6期21卷 589-594页

作者： Peng Gao Cheng-chang Jia Wen-bin Cao cong-cong wang Dong Liang Guo-liang Xu School of Materials Science and Engineering University of Science and Technology Beijing

In this study, we have investigated how the dielectric loss tangent and permittivity of AlN ceramics are affected by factors such as powder mixing methods, milling time, sintering temperature, and the addition of a second conductive phase. All ceramic samples were pre-pared by spark plasma sintering （SPS） under a pressure of 30 MPa. AlN composite ceramics sintered with 30wt%-40wt%SiC at 1600℃ for 5 min exhibited the best dielectric loss tangent, which is greater than 0.3. In addition to AlN and β-SiC, the samples also contained 2H-SiC and Fe5Si3, as detected by X-ray difraction （XRD）. The relative densities of the sintered ceramics were higher than 93%. Experimental results indicate that nano-SiC has a strong capability of absorbing electromagnetic waves. The dielectric constant and dielectric loss of AlN-SiC ce-ramics with the same content of SiC decreased as the frequency of electromagnetic waves increased from 1 kHz to 1 MHz.

关键词： ceramic materials composite materials aluminum nitride silicon carbide spark plasma sintering dielectric losses

Influence of plasma on the densification mechanism of SPS under multi-field effect

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International Journal of Minerals,Metallurgy and Materials 2014年第9期21卷 906-912页

作者： Yu-hong Chang Di Huang Cheng-chang Jia Zhao-wen Cui cong-cong wang Dong Liang School of Materials Science and Engineering University of Science and Technology Beijing

The densification mechanism of an Fe-based alloy powder containing tiny oxide particles under the synergic multi-field effect of spark plasma sintering （SPS） was investigated. Metallographic microscopy and scanning electron microscopy were used to observe the morphology of samples sintered at different temperatures, and the temperature dislribution in an individual spherical powder particle during sintering was calculated in consideration of the influence of plasma, which was qualified and quantified through the analysis of the U-Icurve. The plasma was observed to play a substantial role in activating and heating the samples at the very early stage of sintering, whereas the joule-heat effect played a dominant role during sintering. Moreover, the plasma also facilitated the diffusion and migration of materials for neck formation.

关键词： iron alloys spark plasma sintering plasma temperature distribution densification diffusion

Solitary necrotic nodules of the liver with"ring"-like calcification:A case report

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World Journal of Clinical Cases 2022年第21期10卷 7409-7414页

作者： Jin-Peng Bao Hu Tian Hao-Chen wang cong-cong wang Bo Li Department of General Surgery The First Affiliated Hospital of Shandong First Medical University&Shandong Provincial Qianfoshan HospitalJinan 250014Shandong ProvinceChina Department of Gastroenterology Shandong First Medical UniversityJinan 250024Shandong ProvinceChina Department of General Surgery Shandong Provincial Qianfoshan HospitalShandong UniversityJinan 250100Shandong ProvinceChina

BACKGROUND Solitary necrotic nodule of the liver(SNNL)is a rare benign lesion with a complete necrotic core and a clear fibrous capsule containing elastic *** present the case of a patient with a radiographic computed tomography(CT)finding of"ring"-like annular calcification within the lesion and postoperative pathologic diagnosis of necrotic nodules wrapped by dense fibers in liver tissue,as well as the patient's subsequent management and *** SUMMARY A 38-year-old Chinese woman with a history of systemic lupus erythematosus treated with prednisone and hydroxychloroquine,without any symptoms,was found to have hepatic space-occupying lesions by imaging examination at a health examination.A subsequent CT scan suggested a space-occupying lesion of the liver with annular calcification,which was not defined to be benign or *** that,a laparoscopic hepatic space-occupying resection was *** postoperative pathological diagnosis was necrotic nodules wrapped by dense fibers in the liver tissue,and the final diagnosis was *** patient had an uneventful postoperative *** There is a"ring"-like calcification in *** patient had a history of systemic lupus erythematosus,without a history of parasite infection,trauma,or ***,whether the etiology and pathological changes of SNNL are related to rheumatic immune diseases remains to be investigated.

关键词： Solitary necrotic nodules of the liver Annular calcification Rheumatic immune disease Laparoscopic hepatic space-occupying resection Case report

Dielectric properties of AlN/Mo composite ceramics prepared by spark plasma sintering method at different processing conditions

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Rare Metals 2022年第4期41卷 1369-1374页

作者： Peng Gao Cheng-Chang Jia Wen-Bin Cao cong-cong wang Guo-Liang Xu Dong Liang Zhao-Wen Cui School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

In this study,the effects of powder mixed method,sintering temperature,and the additive amount of the conductive phase on the dielectric loss tangent and permittivity constant of AlN/Mo composite ceramics were *** the ceramic samples were prepared by spark plasma sintering(SPS).AlN composite ceramics with additional 10 vol%Mo sintered at 1400℃holding for 5 min exhibit the best dielectric loss tangent,which is greater than ***/Mo ceramics with additional 20 vol%Mo become conductive,with the resistivity of 0.05–0.06Ω·***-energy ball milling is better than magnetic stirring powder mixing *** addition,the additive Mo and lower sintering temperature lead to a better property with the increase in the electromagnetic wave frequency range of 1×10^(3)–1×10^(6)Hz.

关键词： Aluminum nitride Molybdenum Dielectric loss Spark plasma sintering

Deterministic Learning-Based Neural PID Control for Nonlinear Robotic Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1227-1238页

作者： Qinchen Yang Fukai Zhang cong wang The authors are with the School of Control Science and Engineering Shandong UniversityJinan 250061China

Traditional proportional-integral-derivative(PID)controllers have achieved widespread success in industrial ***,the nonlinearity and uncertainty of practical systems cannot be ignored,even though most of the existing research on PID controllers is focused on linear ***,developing a PID controller with learning ability is of great significance for complex nonlinear *** article proposes a deterministic learning-based advanced PID controller for robot manipulator systems with *** introduction of neural networks(NNs)overcomes the upper limit of the traditional PID feedback mechanism’s *** proposed control scheme not only guarantees system stability and tracking error convergence but also provides a simple way to choose the three parameters of PID by setting the proportional *** the partial persistent excitation(PE)condition,the closed-loop system unknown dynamics of robot manipulator systems are accurately approximated by *** on the acquired knowledge from the stable control process,a learning PID controller is developed to further improve overall control performance,while overcoming the problem of repeated online weight *** studies and physical experiments demonstrate the validity and practicality of the proposed strategy discussed in this article.

关键词： PID robot system

Gait Recognition Under Different Clothing Conditions Via Deterministic Learning

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1530-1532页

作者： Muqing Deng cong wang School of Automation Guangdong University of TechnologyGuangzhou 510006China School of Control Science and Engineering Shandong UniversityJinan 250100China

Dear Editor,This letter deals with the robustness problem of gait recognition method against maximum number of clothing *** selecting four kinds of time-varying silhouette features,gait dynamics underlying different individuals’gait features is effectively modeled by radial basis function(RBF)neural networks through deterministic *** kind of dynamics information has little sensitivity to the variance between gait patterns under different clothing *** order to eliminate the effect of clothing differences,the training patterns under different clothing conditions further constitute a uniform training dataset,containing all kinds of gait dynamics under different clothing conditions.A rapid recognition scheme is presented on published gait *** experiments demonstrate the efficacy of the proposed method.

关键词： networks neural individual

Combustion and Self-Desulfurization Characterization of Blended Low-Rank Coals for Improved Resource Utilization in Fluidized Bed Boilers

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Journal of Thermal Science 2024年第3期33卷 1242-1256页

作者： SU Lipeng ZHANG cong ZHANG Yongsheng wang Tao wang Jiawei Key Laboratory of Power Station Energy Transfer Conversion and System Ministry of EducationNorth China Electric Power UniversityBeijing102206China

The co-combustion of low-rank coals through fluidized bed boiler(CFB)is an effective approach to enhance the level of resource *** date,there has been a lack of investigation concerning the co-combustion kinetics and self-desulfurization characteristics of coal slime,coal gangue,and raw *** this study,we adopted multiple model-free and model-fitting methods to comparatively analyze co-combustion kinetics of blended coals on the basis of thermogravimetric ***,the sulfur balance and self-desulfurization of blended coals in the co-combustion were intensively investigated using a tube furnace *** results reveal that in the presence of coal gangue in blended coals,the average activation energy(E_(a))falls within the range of 65.7 kJ/mol to 100.4 kJ/mol,as determined by four model-free ***,in the absence of coal gangue,only the Flynn-Wall-Ozawa(FWO)and Friedman(FM)methods are deemed appropriate for calculating the average E_(a),yielding a value of 77.3 kJ/*** first order reaction model is confirmed to be reliable for analyzing the co-combustion kinetics of low-rank blended *** of the specific composition of the blended coal,a significant linear correlation exists between the Ea and the natural logarithm of the pre-exponential factor(lnA)within an extensive range of ***,the addition of coal gangue to the blended coal substantially enhances the self-desulfurization level,resulting in an increase from 25.7%to60.7%at 1073 *** self-desulfurization efficiency exhibits a good linear relationship with both the mass ratio of coal gangue to coal slime and the molar ratio of calcium to *** a practical implementation,the optimal addition ratio of coal gangue is a trade-off between the self-desulfurization efficiency and the ignition capacity.

关键词： coal slime coal gangue fluidized bed boilers self-desulfurization resource utilization