检索结果-南通市图书馆

Frontiers of Environmental Science & Engineering 2019年第4期13卷 101-111页

作者： Peng Hu Changsheng Guo Yan zhang Jiapei Lv Yuan zhang Jian Xu State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China

This study investigated the presence of 11 abused drugs and their metabolites, including amphetamine, methamphetamine (METH), ketamine, ephedrine (EPH), cocaine, benzoylecgonine, methadone, morphine, heroin, codeine, and methcathinone in the surface water and sediment samples of Beiyunhe River, a typical urban river flowing through Beijing, Tianjin, and Hebei provinces in North China. An analytical method of determining these abused drugs and their metabolites in water and sediment was developed and validated prior to sample collection in the study area. Results showed that METH and EPH were predominant in water and sediment samples. The total drug concentrations ranged from 26.6 to 183.0 ng/L in water and from 2.6 to 32.4 ng/g dry weight in sediment, and the drugs mainly originated from hospitals and sewage treatment plants. The average field-based sediment water distribution coefficients of abused drugs were calculated between 149.3 and 1214.0 L/kg and corrected by organic carbon. Quotient method was used to assess the risks. The findings revealed that these drugs and their metabolites at determined concentrations in water samples will not impair the aquatic ecosystem biologically, but their potential harmful effect on the function of the ecosystem and human health should not be overlooked.

关键词： Drugs of abuse Occurrence Distribution Urban river Environmental risk

A novel handover scheme for millimeter wave network:An approach of integrating reinforcement learning and optimization

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Digital Communications and Networks 2024年第5期10卷 1493-1502页

作者： Ruiyu Wang Yao Sun Chao zhang Bowen Yang Muhammad Imran Lei zhang School of Engineering University of Glasgow Shanghai Shiyue Computer Technology Co. Ltd

The millimeter-Wave(mmWave) communication with the advantages of abundant bandwidth and immunity to interference has been deemed a promising technology to greatly improve network ***,due to such characteristics of mmWave,as short transmission distance,high sensitivity to the blockage,and large propagation path loss,handover issues(including trigger condition and target beam selection) become much *** this paper,we design a novel handover scheme to optimize the overall system throughput as well as the total system delay while guaranteeing the Quality of Service(QoS) of each User Equipment(UE).Specifically,the proposed handover scheme called O-MAPPO integrates the Reinforcement Learning(RL) algorithm and optimization *** RL algorithm known as Multi-Agent Proximal Policy Optimization(MAPPO) plays a role in determining handover trigger ***,we propose an optimization problem in conjunction with MAPPO to select the target base *** aim is to evaluate and optimize the system performance of total throughput and delay while guaranteeing the QoS of each UE after the handover decision is *** numerical results show the overall system throughput and delay with our method are slightly worse than that with the exhaustive search method but much better than that using another typical RL algorithm Deep Deterministic Policy Gradient(DDPG).

关键词： Reinforcement learning Optimization theory MmWave Cellular network Handover

High antibiotic resistance rate: A difficult issue for Helicobacter pylori eradication treatment

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2015年第48期21卷 13432-13437页

作者： Mei zhang Department of Gastroenterology Xuanwu HospitalCapital Medical University

Helicobacter pylori(H. pylori) infection is associated with a variety of upper gastrointestinal diseases, including gastric cancer. With the wide application of antibiotics in H. pylori eradication treatment, drugresistant strains of H. pylori are increasing. H. pylori eradication treatment failure affects the outcome of a variety of diseases of the upper gastrointestinal tract. Therefore, antibiotic resistance that affects H. pylori eradication treatment is a challenging situation for clinicians. The ideal H. pylori eradication therapy should be safe, effective, simple, and economical. The eradication rate of triple antibiotic therapy is currently less than 80% in most parts of the world. Antibiotic resistance is the main reason for treatment failure, therefore the standard triple regimen is no longer suitable as a first-line treatment in most regions. H. pylori eradication treatment may fail for a number of reasons, including H. pylori strain factors, host factors, environmental factors, and inappropriate treatment.

关键词： Helicobacter pylori Resistance Eradicationtreatment Triple antibiotic therapy Gastrointestinaldisease

Evolution of microstructure and high temperature tensile properties of as-extruded Ti Bw reinforced near-α titanium matrix composite subjected to heat treatments

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2018年第9期61卷 1340-1345页

作者： WANG Bo zhang HaoBiao HUANG LuJun HE JianLi zhang YouFeng WANG Wei School of Materials Engineering Shanghai University of Engineering Science Shanghai 201620 China Shanghai Collaborative Innovation Center of Laser Advanced Manufacturing Technology Shanghai 201620 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The Ti Bw reinforced near-α titanium matrix composite（Ti-5.8 Al-3.4 Zr-4.0 Sn-0.4 Mo-0.4 Nb-0.4 Si-0.06 C） was successfully synthesized by powder metallurgy and hot extrusion route. The effects of solution and aging temperature on the microstructure and high temperature tensile properties of the composite were investigated. The results revealed that the fine transformed β phase can be obtained by the solution treatment at β phase region and aging treatment, no other precipitates were observed. The α2 phase（Ti3 Al） can be acquired when the solution treated at α＋β phase region followed by aging treatment. With increasing the aging temperature from 500 to 700℃ for 5 h, the size of α2 precipitates increases from about 5 to about 30 nm. The Ti Bw are stable without any interfacial reaction during the heat treatments. The high temperature tensile properties show that the composite performed by solution and aging treatment exhibits good strengthening effects. With increasing the aging temperature from 500 to 700℃, the strength of the composite increases at the expense of elongation due to the increment of α2 *** strength of the composite at 600℃ increases by 17% to 986 MPa after 1000℃/2 h/AC and 700℃/5 h/AC heat treatment.

关键词： titanium matrix composite solution aging precipitate microstrueture high temperature tensile property

Influence of Gd_2O_3 and Yb_2O_3 Co-doping on Phase Stability,Thermo-physical Properties and Sintering of 8YSZ

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2012年第6期25卷 948-953页

作者： zhang Yanli GUO Lei YANG Yongping GUO Hongbo zhang Hongju GONG Shengkai School of Materials Science and Engineering Beihang University Beijing 100191 China Guizhou LiyangAviation Power Co. Ltd. Anshun 561102 China

The role of multicomponent rare earth oxides in phase stability, thermophysical properties and sintering for ZrO2-based thermal barrier coatings （TBCs） materials is investigated. 8YSZ codoped with 3 mol% Gd2O3 and 3 mol% Yb2O3 （GYb-YSZ） powders are synthesized by solid state reaction for 24 h at various temperatures. As temperature increases, stabilizers are dissolved into zirconia matrix gradually. Synthesized at 1 500 °C, GYb-YSZ is basically composed of cubic phase. GYb-YSZ exhibits excellent phase stability and sinters lower than 8YSZ by nearly three times. The thermal conductivity of GYb-YSZ is much lower than that of 8YSZ, and the thermal expansion coefficient of GYb-YSZ is comparable to that of 8YSZ. The influence of Gd2O3 and Yb2O3 co-doping on phase stability, thermal conductivity and sintering of 8YSZ is discussed.

关键词： thermal barrier coatings (TBCs) Gd2O3 and Yb2O3 co-doped 8YSZ (GYb-YSZ) phase stability sintering ther-mo-physical properties

Mass production of magnetocaloric LaFeMnSiB alloys with hydrogenation

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2017年第4期24卷 462-468页

作者： Tao zhang Cheng-yong Wang Lugee Li Yong zhang Cui-lan Liu Guangdong University of Technology Guangzhou 510006GuangdongChina Dongguan Eontech Co. Ltd.Dongguan 523662GuangdongChina State Key Laboratory of Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Baotou Research Institute of Rare Earth Baotou 014030Inner MongoliaChina

LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）Hxalloys were prepared by *** were annealed at 1343Kfor30-90 hto form the NaZn13 ***-rich andα-Fe secondary phases were also *** hydrogenation at 553 Kand 0.15 MPa of H_2 pressure for 5hwas employed to improve the Curie temperature of the alloys to 279 *** maximum magnetic entropy change,relative cooling power,and adiabatic temperature change of LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x annealed at 1343 Kfor 90hafter hydrogen absorption are 6.38J/（kg·K）（magnetic changesμ0ΔH =1.65T）,100.1J/kg（μ0ΔH =1.65T）,and 2.2 K（μ0ΔH =1.48T）,*** the maximum magnetic entropy change of the LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x alloys is lower than those of similar alloys with high purity raw materials,the relative cooling power is nearly the *** effect of impurities of the raw materials used was also *** is assumed that the impurity of 0.2wt.% Al is responsible for the reduced entropy change of the resulted *** LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x alloys prepared by this method could be a low cost alternative material for room temperature magnetic cooling applications.

关键词： Magnetocaloric effect Annealing Hydrogenation Adiabatic temperature change Relative cooling power Maximum magnetic entropy change

Development of a portable cold air plasma jet device and observation of its photo ionization process

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2020年第8期22卷 99-108页

作者： Zhaoquan CHEN Jinfang WU Huang zhang Ming zhang Sanyang zhang Deren FENG Anhui Key Laboratory of Electrical Drive and Power Electronics Anhui University of TechnologyMaanshan 243032People's Republic of China

Photo ionization plays a critical role in the formation and propagation of atmospheric pressure plasma jet *** in experiments,it is very difficult to observe the photo ionization due to its relative lower density of photo *** the present study,we develop a portable cold air plasma jet device and observe the ionization wave in adc spark air plasma *** discharge images acquired by an ICCD camera show that the ionization wave front performs as a quickly moving bright *** could take place at another side of the quartz plate or pork tissue layer(6 mm thick),which suggests that the ionization should be attributed to photo *** laser schlieren images indicate there is propagation of a shock wave along with the plasma *** on the photo ionization theory and the photo-electric measurement,the direct photo ionization and multistage photo ionization are the main factors in charge of generating the cold air plasma *** addition,the plasma jet outside of the cathode nozzle is colder than 320 K and can be touched safely by a *** view of the plasma jet including a large amount of active particles,such as NO,O,OH,emitted photons,etc,the proposed portable cold air plasma jet device could be qualified for plasma bio-medicine applications.

关键词： photo ionization air plasma jet plasma bullet ionization wave

Inter-hour direct normal irradiance forecast with multiple data types and time-series

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2019年第5期7卷 1319-1327页

作者： Tingting ZHU Hai ZHOU Haikun WEI Xin ZHAO Kanjian zhang Jinxia zhang Key Laboratory of Measurement and Control of CSE Ministry of EducationSchool of AutomationSoutheast UniversityNanjing 210096China State Key Laboratory of Operation and Control of Renewable Energy and Storage Systems(China Electric Power Research Institute) Nanjing 210003China

Boosted by a strong solar power market,the electricity grid is exposed to risk under an increasing share of fluctuant solar *** increase the stability of the electricity grid,an accurate solar power forecast is needed to evaluate such *** terms of forecast,solar irradiance is the key factor of solar power generation,which is affected by atmospheric conditions,including surface meteorological variables and column integrated *** variables involve multiple numerical timeseries and ***,few studies have focused on the processing method of multiple data types in an interhour direct normal irradiance(DNI)*** this study,a framework for predicting the DNI for a 10-min time horizon was developed,which included the nondimensionalization of multiple data types and time-series,development of a forecast model,and transformation of the *** atmospheric variables were considered in the forecast framework,including the historical DNI,wind speed and direction,relative humidity time-series,and ground-based cloud *** were conducted to evaluate the performance of the forecast *** experimental results demonstrate that the proposed method performs well with a normalized mean bias error of 0.41%and a normalized root mean square error(n RMSE)of20.53%,and outperforms the persistent model with an improvement of 34%in the nRMSE.

关键词： Inter-hour forecast Direct normal irradiance Ground-based cloud images Multiple data types Multiple time-series

Model moisture transport in oil-paper insulation of transformer:Theory and experiment

在线全文

学校读者我要写书评

暂无评论

High Voltage 2024年第4期9卷 879-887页

作者： Junjie Zhou Zhicheng Wu Yiran Guo Rui zhang Wenbing Zhu Qiaogen zhang State Key Laboratory of Electric Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina State Grid Shandong Electric Power Research Institute JinanChina

The insulation performance of oil paper insulation is significantly affected by moisture such that monitoring moisture content is ***,it is difficult to obtain the moisture content accurately due to its dynamic change under multi physical *** the moisture transportation in oil paper insulation under multi physical fields becomes a vital method in solving the problem.A multi physical model describing moisture migration was proposed,which considered the effects of temperature on moisture in different existing states in oil-immersed paper(OIP).The temperature distribution formed a vapour pressure gradient to drive moisture migration and affected migration ***,experiments and simulations of moisture migration were performed,which showed that the experiments were in good agreement with *** results revealed that the temperature gradient caused uneven moisture distribution and the increased temperature reduced OIP moisture *** established model could fully characterise moisture migration under temperature gradient,which provided a theoretical reference for predicting the risk of partial dampness and evaluating insulation performance.

关键词： moisture insulation distribution

Thermo-and pH-dual responsive inorganic-organic hybrid hydrogels with tunable luminescence

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2018年第3期61卷 328-335页

作者： Jinlong zhang Haibing Wei Junyan Tan Weihong Qiao Yan Guan Jie zhang State Key Laboratory of Fine Chemicals School of Chemical Engineering Dalian University of Technology Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of Education College of Chemistry and Molecular Engineering Peking University School of Chemistry and Chemical Engineering Provincial Key Laboratory of Advanced Functional Materials and Devices Hefei University of Technology

A thermo-and pH-dual responsive luminescent hydrogel was successfully constructed by coupling dysprosium-containing polyoxometalates Na_9 DyW_(10) O_(36)(DyW_(10)) with the ABA triblock copolymer, where the B block is PEO and the A block is the thermosensitive poly(methoxydi(ethylene glycol) methacrylate-co-N,N-dimethylaminoethyl methacrylate). The complex hybrid underwent a sol-gel phase transition above the lower critical solution temperature(LCST) of the A block. DyW_(10) was electrostatically encapsulated into the hydrophobic domain of the A block with enhanced photoluminescence. When temperature cooled down, the luminescence could be restored. By addition of acids to protonate the A block, and emission of DyW_(10) was simultaneously enhanced. Sensitivity of poly(N,N-dimethy laminoethyl methacrylate)(PDMAEMA) to pH also enabled the emission of DyW_(10)/copolymer hydrogel to be reversibly switched by alternating acid/base treatments.

关键词： stimuli responsive block copolymer polyoxometalate hydrogel luminescence