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Variations in the effective and bankfull discharge for suspended sediment transport due to dam construction

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Frontiers of Earth Science 2022年第2期16卷 446-464页

作者： Fan CHEN Li CHEN wei zhang Jing YUAN Kanghe zhang State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Changjiang Institute of Survey PlanningDesign and ResearchWuhan 430010China Bureau of Hydrology Changjiang Water Resources CommissionWuhan 430010China

A varied class method is applied to calculate the effective discharges and their variations after the Three Gorges Dam(TGD)construction based on the mean daily flow discharge and suspended sediment concentration field data from 1981 to *** comparison,the bankfull discharges are also determined according to the cross-section profiles and flow discharge-stage *** results show that a bimodal effective discharge curve usually exists at the fixed sites,which generates two effective discharges(Q_(e1) and Q_(e2))within the moderate flow *** the quasi-equilibrium circumstances of the pre-dam period,effective discharges are closely related to the mean annual runoff,with a narrow range of regional variations in occurrence *** analyses draw the conclusion that the relatively higher unsaturation degrees of the pre-dam effective discharges caused by dam interception and riverbed coarsening are the primary cause of the increase in effective discharges from Yichang to Shashi,while the more frequent low and medium discharges due to flow regulation drive the decrease in effective discharges from jianli to *** slightly elevated flood levels and descending bankfull levels collaboratively result in the decrease of bankfull discharges from Yichang to Shashi,while the lowered bed elevation causes the increase in bankfull discharges from Luoshan to ***,the bankfull discharge in the Middle and Lower Yangtze River is larger than effective discharge and approaches the 1.5-year recurrence interval discharge.

关键词： effective discharge bankfull discharge unsaturation degree flow-sediment regimes Middle and Lower Yangtze River Three Gorges Dam

Bi-dimension decomposed hidden Markov models for multi-person activity recognition

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 810-819页

作者： wei-dong zhang Feng CHEN Wen-li XU Department of Automation Tsinghua University Beo'ing 100084 China

We present a novel model for recognizing long-term complex activities involving multiple persons. The proposed model, named ‘decomposed hidden Markov model’ (DHMM), combines spatial decomposition and hierarchical abstraction to capture multi-modal, long-term dependent and multi-scale characteristics of activities. Decomposition in space and time offers conceptual advantages of compaction and clarity, and greatly reduces the size of state space as well as the number of parameters. DHMMs are efficient even when the number of persons is variable. We also introduce an efficient approximation algorithm for inference and parameter estimation. Experiments on multi-person activities and multi-modal individual activities demonstrate that DHMMs are more efficient and reliable than familiar models, such as coupled HMMs, hierarchical HMMs, and multi-observation HMMs.

关键词： Multi-channel setting Hierarchical modeling Hidden Markov model Activity recognition

Graphite dust resuspension in an HTR-10 steam generator

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Particuology 2014年第6期12卷 149-157页

作者： wei Peng Tianqi zhang Yanan Zhen Suyuan Yu Institute of Nuclear and New Energy Technology of Tsinghua University Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering of Ministry of EducationsDepartment of Thermal EngineeringTsinghua University

Graphite dust has an important effect on the safety of high-temperature gas-cooled reactors（HTR）.The flow field in the steam generator was studied by the computational fluid dynamics（CFD） method,with the results indicating that the friction velocity in the windward and the leeward of the heat transfer tubes is relatively low and is higher at the *** analysis of the resuspension of graphite dust indicates that the resuspension fraction reaches nearly zero for particles with a diameter less than 1 μm,whereas it will increases as the helium velocity in the steam generator increases for particle size larger than 1 μ***,the resuspension fraction increases as the particle size *** results also indicate that resuspension of the particles with sizes larger than 1 μm exhibited obvious differences in different parts of the steam generator.

关键词： Graphite dust High-temperature gas-cooled reactor(HTR) Steam generator Resuspension

Improving the stability of LiNi_(0.80)Co_(0.15)Al_(0.05)O_2 by AlPO_4 nanocoating for lithium-ion batteries

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Science China Chemistry 2017年第9期60卷 1230-1235页

作者： Ran Qi Ji-Lei Shi Xu-Dong zhang Xian-Xiang Zeng Ya-Xia Yin jian Xu Li Chen wei-Gui Fu Yu-Guo Guo Li-Jun Wan State Key Laboratory of Separation Membranes and Membrane Processes School of Materials Science and EngineeringTt'anjin Polytechnic UniversityTianjin 300071China CAS Research/Education Center for Excellence in Molecular Sciences Institute of ChemistryChinese Academy of SciencesBeo'ing 100190China School of Chemistry and Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

Nickel-rich layered materials,such as LiNi_(0.8)0Co_(0.15)Al_(0.05)O_2(NCA),have been considered as one alternative cathode materials for lithium-ion batteries(LIBs) due to their high capacity and low ***,their poor cycle life and low thermal stability,caused by the electrode/electrolyte side reaction,prohibit their prosperity in practical ***,AlPO4 has been homogeneously coated on the surface of NCA via wet chemical method towards the target of protecting NCA from the attack of *** with the bare NCA,NCA@AlPO_4 electrode delivers high capacity without sacrificing the discharge capacity and excellent cycling *** 150 cycles at 0.5 C between 3.0-4.3 V,the capacity retention of the coated material is 86.9%,much higher than that of bare NCA(66.8%).Furthermore,the thermal stability of cathode is much improved due to the protection of the uniform coating layer on the surface of *** results suggest that AlPO4 coated NCA materials could act as one promising candidate for next-generation LIBs with high energy density in the near future.

关键词： Li-ion batteries cathode materials surface modification AlPO4 coating

Characteristics of isothermal adsorption and desorption of aluminum ion to/from humic acids

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Journal of Environmental Sciences 2008年第5期20卷 579-584页

作者： WANG Qiang wei Shiqiang HUANG Yuming zhang Jinzhong College of Resources and Environment Southwest University Chongqing 400716 China Chongqing Key Laboratory of Agricultural Resources and Environment Chongqing 400716 China College of Chemistry and Chemical Engineering of Southwest University Chongqing 400715 China

The adsorption and desorption characteristics of Al^3＋ to/from humic acids at different pH, ionic strength, and temperature were studied by the C-25 glucosan-gel chromatography method. The results showed that the maximum adsorption amount （Qmax） and adsorption constant （k） increased, whereas, the absolute value of standard thermodynamic molar free energy change （ΔGm^0） decreased with the increase of pH at constant ionic strength and temperature. With ionic strength increasing from 0 to 0.15 mol/L, Qmax, and k increased and the absolute value of ΔGm^0 decreased at constant pH and temperature. High temperature was unfavorable for the adsorption reaction, as indicated by the dramatic decrease of Qmax and the absolute value of ΔGm^0 with an increase in temperature. The standard thermodynamic molar free energy change （ΔGm^0） and the standard thermodynamic enthalpy change （ΔHm^0） of the adsorption reaction were both negative, suggesting that adsorption reaction was spontaneous and exothermic. The desorption rate of HA-Al^3＋ complex accelerated with the decrease of pH, and a significant linear relationship could be obtained between pH and the desorption rates of Al^3＋ from humic acids. These results demonstrated that the Al^3＋ adsorption reaction was a ＂biphase＂ reaction, and adsorption occurred at both the interior and exterior adsorption sites of humic acids.

关键词： adsorption and desorption characteristics Al^3+ humic acid

Highly stable metal halides Cs_(2)ZnX_(4)(X = Cl, Br) with Sn2+ as dopants for efficient deep-red photoluminescence

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Chinese Chemical Letters 2023年第2期34卷 362-366页

作者： Yan zhang Lei Zhou Lei zhang wei Luo wei Shen Ming Li Rongxing He Key Laboratory of Luminescence Analysis and Molecular Sensing(Southwest University) Ministry of EducationCollege of Chemistry and Chemical EngineeringSouthwest UniversityChongqing 400715China

The development of deep-red emitting lead-free metal-halide perovskites with high photoluminescence quantum yields (PLQYs) and outstanding stability remains a major challenge for displays and deep-tissue *** this work,we report a facile and convenient solvothermal method to synthesize metal halides Cs_(2)Zn X_(4)(X=Cl,Br) that however is PL innert at room *** composition engineering utilizing Sn^(2+) as the dopant,the resulting Cs_(2)Zn Cl_(4):Sn not only emits strong deep-red PL peaked at700 nm with the highest 99.4%PLQY among the similar materials so far,but also exhibits excellent structure stability in air (PLQY remains 96%after one year exposure to the atmosphere).Detailed experimental characterizations and theoretical calculations reveal that the deep-red emission stems from self-trapped excitons induced by the Sn^(2+) ***,triplet emission (^(3)P_(2)→^(1)S_(0)) from Sn-5s^(2) orbitals has been observed at low temperature due to the break of parity-forbidden *** work provides an important guidance for the development of deep-red light-emitting materials with low price,high efficiency and excellent stability.

关键词： Lead-free metal halides Deep-red emission Photoluminescence High efficiency Stability

Improved multi-target radar TBD algorithm

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Journal of Systems Engineering and Electronics 2015年第6期26卷 1229-1235页

作者： Xin Bi Jinsong Du Qingshi zhang wei Wang Shenyang Institute of Automation Chinese Academy of Sciences Key Laboratory on Radar System Research and Application Technology of Liaoning Province

Considering radar detection for multi-target recognition, a track before detect （TBD） algorithm based on Hough transform is adopted for identifying and tracking multi-target radar. By increasing the dimensions of the target characteristic parameters, the target detection and track accuracy is increased. Also, by multilevel filtering processing, the diverging points of the echo signal are condensed, which improves the performance of identifying and tracking multiple targets. Simulation results show that compared with traditional TBD algorithms, the presented algorithm has better performance in the aspects of multi-target tracking, detecting and distinguishing.

关键词： track before detect (TBD) Hough transform multi-dimensional Kalman filter.

Characteristics of blood glucose excursions in type 2 diabetes mellitus patients with three different Traditional Chinese Medicine syndromes

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Journal of Traditional Chinese Medicine 2015年第5期35卷 537-545页

作者： zhang Hongyan Zhou jian zhang Lei Ma jianhui Sun Yongning Zhao Yuwu Internal Medicine of Traditional Chinese Medicine Chengdu University of Traditional Chinese Medicine Department of Traditional Chinese Medicine the Sixth People's Hospital affiliated to Shanghai Jiao Tong University Department of Endocrinology and Metabolism the Sixth People's Hospital affiliated to Shanghai Jiao Tong University School of Foreign Languages China University of Political Science and Law Department of Neurology the Sixth People's Hospital affiliated to Shanghai Jiao Tong University

OBJECTIVE:To explore the characteristics of blood glucose excursions of type 2 diabetes mellitus patients with three different Traditional Chinese Medicine(TCM) ***:One hundred and nine patients with type 2 diabetes mellitus were recruited from the Department of Endocrinology and the Department of TCM of the Sixth People's Hospital affiliated to Shanghai Jiao Tong *** were divided into three groups according to TCM syndrome:intrinsic Damp(n- 42),Yin deficiency and internal Heat(n = 25),and Qi and Yin deficiency(n- 42).Subcutaneous interstitial glucose was monitored with a continuous glucose monitoring system for 3consecutive days to investigate the glycemic profile in each *** C-peptide levels were measured,and an arginine test was taken in 10 patients randomly selected from each *** data and glycemic variability were analyzed to investigate the differences among the *** change in C-peptide levels and the results from arginine trial were used to evaluate β cell ***:Indicators reflecting blood glucose level were the highest in subjects with Yin deficiency and internal Heat syndrome,and parameters reflecting glycemic variability were the lowest in those with Qi and Yin deficiency *** change in C-peptide levels showed that subjects with Qi and Yin deficiency syndrome had the best βcell function among the three groups;this was confirmed by the arginine ***:Patients with Qi and Yin deficiency syndrome had a more stable blood glucose profile,as glycemic variability was higher in those with intrinsic Damp syndrome and those with Yin deficiency and internal Heat syndrome.

关键词： Blood glucose excursions Glycemic variability Symptom complex Diabetes mellitus type 2

Study on Titanium Alloy TC4 Ballistic Penetration Resistance Part I:Ballistic Impact Tests

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Chinese Journal of Aeronautics 2012年第3期25卷 388-395页

作者： zhang Tao CHEN wei GUAN Yupu GAO Deping College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016China

Ballistic impact test of different-scale casings is an efficient way to demonstrate the casing containment capability at the preliminary design stage of the engine. For the sake of studying the titanium alloy TC4 casing perfonnance, the ballistic tests of flat and curved simulation casing are implemented by using two flat blades of different sizes as the projectile. The impact mechanism and failure of the target are discussed. Impact of the projectile is a highly nonlinear transient process with the large deformation of the target. On the impact, failures of the flat casing and the subscale casing are similar, concluding two parts, the global dish- ing and localized ductile tearing. The main localized failure mode combines plugging （shear） and petaling （shear） if the projectile perforates or penetrates, while crater （shear） if the projectile rebounds. The ballistic limit equation is verified by the test data and the results show that this empirical equation could be a practical way to estimate the critical velocity.

关键词： containment casing ballistic penetration damage mechanism failure mode