检索结果-南通市图书馆

Frost Resistance of Pervious Concrete Mixed with Waste Glass Powder

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1325-1336页

作者： AN Baofeng LI Qiong QIAO Hongxia SU Rui WANG Xi WANG Chaoqun JIAO Daowei School of Civil Engineering Lanzhou University of TechnologyLanzhou 730050China Gansu Advanced Civil Engineering Materials Engineering Research Center Lanzhou 730050China china construction First Group The fifth construction Co.Ltd Beijing 100000China

The contents of waste glass powder(WGP)(0%,10%,15%,20%,25%)and water-binder ratio(W/C)(0.24,0.26,0.28)were used as influencing factors,and the quality loss rate(Δm)and compressive strength loss rate(Δfc)were used as characterization *** Ca/Si ratio and main element contents of C-S-H gels with different WGP content were investigated by energy dispersive spectrometry(EDS).The pore structure evolution characteristics of WGP composite cementing materials were investigated by low field nuclear magnetic resonance(NMR).UsingΔfc as the index of frost resistance degradation and Weibull function,the frost resistance degradation of glass doped pervious concrete(WGP-PC)was *** results show that,with WGP,for the same number of cycles,Δm andΔfc decrease and increase with the increase of *** the same WGP content,Δm andΔfc decrease first and then increase with the increase of W/*** 100 freeze-thaw cycles,the samples with WGP content of 20%and W/C of 0.26 have the best *** tests show that with the increase of WGP content,the Ca/Si ratio of C-S-H gel decreases at first and then increases with the increase of WGP *** extreme value of Ca/Si is 2.36 when WGP is added by 20%.The pore volume of hardened paste with 20%WGP content decreased by 18.6%compared with that of cement system without *** overall compactness of the specimen was *** the basis of the test data,a life prediction model was established according to Weibull *** experiment showed thatΔfc could be used as a durability degradation index,and the slope of the reliability curve became gentle after WGP was added,which reduced the damage degradation rate of PC.W/C was ***'s about 5000 hours.

关键词： pervious concrete glass powder frost resistance energy dispersive analysis test low field nuclear magnetic resonance instrument life prediction

Predicting torsional capacity of reinforced concrete members by data-driven machine learning models

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第3期18卷 444-460页

作者： Shenggang CHEN Congcong CHEN Shengyuan LI Junying GUO Quanquan GUO Chaolai LI School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 211116China Jiangsu Key Laboratory Environmental Impact and Structural Safety in Engineering China University of Mining and TechnologyXuzhou 211116China china nuclear Power Design Co.Ltd. Shenzhen 518031China School of transportation and science engineering Beihang UniversityBeijing 100191China china construction First Group corporation Limited Beijing 100161China

Due to the complicated three-dimensional behaviors and testing limitations of reinforced concrete(RC)members in torsion,torsional mechanism exploration and torsional performance prediction have always been *** the present paper,several machine learning models were applied to predict the torsional capacity of RC *** results of a total of 287 torsional specimens were collected through an overall literature *** of extreme gradient boosting machine(XGBM),random forest regression,back propagation artificial neural network and support vector machine,were trained and tested by 10-fold cross-validation *** performances of proposed machine learning models were evaluated and compared,both with each other and with the calculated results of existing design codes,i.e.,GB 50010,ACI 318-19,and Eurocode *** results demonstrated that better predictive performance was achieved by machine learning models,whereas GB 50010 slightly overestimated the torsional capacity,and ACI 318-19 and Eurocode 2 underestimated it,especially in the case of ACI *** XGBM model gave the most favorable predictions with R^(2)=0.999,RMSE=1.386,MAE=0.86,andλ=***,strength of concrete was the most sensitive input parameters affecting the reliability of the predictive model,followed by transverse-to-longitudinal reinforcement ratio and total reinforcement ratio.

关键词： RC members torsional capacity machine learning models design codes

Improved design and construction of an ionization chamber for the CSNS beam loss monitor (BLM)

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

Chinese Physics C 2012年第4期36卷 329-333页

作者：田建民徐美杭赵中亮陈昌阮向东陈元柏徐韬光陆双桐 State Key Laboratory of Technologies of nuclear Detection and Electronics Institute of High Energy Physics Chinese Academy of Sciences Physics Science and Engineering Technology Department Guangxi University Beijing nuclear Instrument Factory China National Nuclear Corporation

Based on the first ionization chamber （IC） prototype, the structure, working gas component and electrode material of the IC are improved. The test of the improved IC shows that the plateau length is about 2000 V, the plateau slope is less than 0.2%/100 V, the sensitivity is 19.6 pA/rad·h 1, the up-limitation of the linearity can be up to 3.6×105 rad/h, and the applied voltage can be operated to 3500 V. The test results show that the performance of the improved IC meets the requirements of the beam loss monitor.

关键词： CSNS BLM detector ionization chamber plateau curve

Design and construction of the first prototype ionization chamber for CSNS and PA beam loss monitor (BLM) system

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2009年第2期33卷 123-126页

作者：徐美杭田建民陈昌陈元柏徐韬光陆双桐 Institute of High Energy Physics CAS Graduate University of Chinese Academy of Sciences Physics Science and Engineering Technology Department Guangxi University china National nuclear corporation Beijing nuclear Instrument Factory

Design and construction of the first prototype ionization chamber for CSNS and Proton Accelerator （PA） beam loss monitor （BLM） system is reported. The low leakage current （〈0.1 pA）, good plateau （≈800 V） and linearity range up to 200 Roentgen/h are obtained in the first prototype. All of these give us good experience for further improving the ionization chamber construction.

关键词： spallation neutron source proton accelerator beam loss monitor ionization chamber plateau curve linearity

Development of a portable and fast wire tension measurement system for MWPC construction

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2016年第9期40卷 114-119页

作者：潘景辉马长利龚学余孙志嘉王艳风尹陈艳龚蕾 University of South china Hengyang 421001China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Dongguan Neutron Science Center Dongguan 523803China State Key Laboratory of Particle Detection and Electronics Beijing 100049China Fujian Fuqing nuclear Power Co. LtdChina National Nuclear CorporationFuqing 350318China

In a multi-wire proportional chamber detector（MWPC）, the anode and signal wires must maintain suitable tension, which is very important for the detector＇s stable and accurate performance. As a result, wire tension control and measurement is essential in MWPC construction. A high pressure3 He MWPC detector is to be used as the thermal neutron detector of the multi-functional reflectometer at china Spallation Neutron Source, and in the construction of the detector, we have developed a wire tension measurement system. This system is accurate,portable and time-saving. With it, the wire tension on an anode wire plane has been tested. The measurement results show that the wire tension control techniques used in detector manufacture are reliable.

关键词： MWPC wire tension tension measurement CSNS

Multi-point discharge model: study on corona discharge of double-ended needle in large space

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2023年第3期25卷 62-69页

作者：李丁晨李家玮李传张明王鹏宇刘志杨勇于克训 International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical Engineering and ElectronicsHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical Engineering and ElectronicsHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China Digital Grid Research Institute China Southern Power GridGuangzhou 510670People’s Republic of China The fifth Bureau of china State construction Engineering corporation Changsha 410000People’s Republic of China

Corona discharge, as a common means to obtain non-equilibrium plasma, can generally obtain high-concentration plasma by increasing discharge points to meet production needs. However,the existing numerical simulation models used to study multi-point corona discharge are all calculations of small-scale space models, which cannot obtain the distribution characteristics of plasma in large space. Based on our previous research, this paper proposes a hybrid model for studying the distribution of multi-point discharge plasma in large-scale spaces, which divides the computational domain and computes separately with the hydrodynamic model and the ion mobility model. The simulation results are verified by a needle–ball electrode device. Firstly, the electric field distribution and plasma distribution of the needle electrodes with single tip and double tips are compared and discussed. Secondly, the plasma distribution of the needle electrode with the double tip at different voltages is investigated. Both computational and experimental results indicate that the charged particle concentration and current of the needle electrode with double tips are both twice as high as those of the needle electrode with a single tip. This model can extend the computational area of the multi-point corona discharge finite element model to the sub-meter(25 cm) or meter level, which provides an effective means to study the plasma distribution generated by multiple discharge points in large-scale space.

关键词： corona discharge numerical simulation multi-point discharge large space double needle tip electrode

Quantitative determination of the electron beam radiation dose for SARS-CoV-2 inactivation to decontaminate frozen food packaging

在线全文

学校读者我要写书评

暂无评论

Virologica Sinica 2022年第6期37卷 823-830页

作者： Zihao Wang Zhentao Liang Rongguo Wei Hongwei Wang Fang Cheng Yang Liu Songdong Meng Key Laboratory of Pathogenic Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing100101China University of Chinese Academy of Sciences Beijing100049China Department of Clinical Laboratory The Fifth Affiliated Hospital of Guangxi Medical UniversityNanning530022China china Isotope and Radiaton corporation Beijing100089China Changchun CNNC CIRC Radiation Technology Co. LTDChangchun130022China

The spread of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) from cold-chain foods to frontline workers poses a serious public health threat during the current global pandemic. There is an urgent need to design concise approaches for effective virus inactivation under different physicochemical conditions to reduce the risk of contagion through viral contaminated surfaces of cold-chain foods. By employing a time course of electron beam exposure to a high titer of SARS-CoV-2 at cold-chain temperatures, a radiation dose of 2 kGy was demonstrated to reduce the viral titer from 10^(4.5)to 0 median tissue culture infectious dose(TCID_(50))/mL. Next,using human coronavirus OC43(HCoV-OC43) as a suitable SARS-CoV-2 surrogate, 3 kGy of high-energy electron radiation was defined as the inactivation dose for a titer reduction of more than 4 log units on tested packaging materials. Furthermore, quantitative reverse transcription PCR(RT-qPCR) was used to test three viral genes,namely, E, N, and ORF1ab. There was a strong correlation between TCID50and RT-qPCR for SARS-CoV-2detection. However, RT-qPCR could not differentiate between the infectivity of the radiation-inactivated and nonirradiated control viruses. As the defined radiation dose for effective viral inactivation fell far below the upper safe dose limit for food processing, our results provide a basis for designing radiation-based approaches for the decontamination of SARS-CoV-2 in frozen food products. We further demonstrate that cell-based virus assays are essential to evaluate the SARS-CoV-2 inactivation efficiency for the decontaminating strategies.

关键词： Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) Inactivation Electron beam radiation Food decontamination Cold-chain

Modular construction mechanics of a European pressurized reactor steel containment liner

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2017年第6期18卷 467-486页

作者： Jia-chuan YAN Xiao-fei JIN Feng QIN Zheng LI Feng FAN Jin-ping OU Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China School of Civil Engineering Harbin Institute of Technology Harbin 150090 China china construction First Engineering Division corporation Limited Beijing 101300 China Country Garden Foshan 528312 China china construction Second Engineering Bureau nuclear Power Plants Branch Shenzhen 518034 China

A European pressurized reactor （EPR） steel containment liner structure is comprised of the cylinder part and the dome part. An introduction of the steel liner structure is presented, followed by studies on the key mechanical features of the construction process using a refined finite element method. The steel liner was divided into several modules and then assembled during construction. Firstly, the equipment structure used to hoist the liner module was optimized, the lifting lug was analyzed using a multi-scale finite element model; the wind speed limit during lifting was also studied. Subsequently, the effect of internal forces during assembly between the liner modules, the lateral pressure of fresh concrete, the non-uniform temperature load, and the wind load on the cylinder module was analyzed. According to the time-varying structural performance during continuous concrete pouring and the hardening construction, an ＂overlapping element and birth-death element＂ technique was adopted to analyze the deformation and stress of the long-span steel dome liner. In addition, the stability-bearing capacities of the dome structure during construction were also studied, which took into consideration the effect of the initial geometrical imperfections and the elasto-plasticity of the material. This study presents a reference in terms of the mechanics of the construction scheme and the safety of such a type of structure.

关键词： Containment construction mechanics Steel liner Overlapping element Birth-death element

Mechanical and acoustic emission characteristics of anhydrite rock under freeze-thaw cycles

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2023年第1期20卷 227-241页

作者： ZHANG Chi JIN Xiao-guang HOU Chao HE Jie School of Civil Engineering Chongqing UniversityChongqing400045China china Railway 14TH Bureau Group Fourth Engineering corporation Limited Jinan250101China Key Laboratory of New Technology for construction of Cities in Mountain Area of the Ministry of Education Chongqing UniversityChongqing400045China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400045China

To study the damage mechanisms of anhydrite rock under freeze-thaw cycles, the physicalmechanical properties and the microcracking activities of anhydrite rock were investigated through mass variation, nuclear magnetic resonance, scanning electron microscope tests, and uniaxial compression combined with acoustic emission(AE) tests. Results show that with the increase of freeze-thaw processes,the mass, uniaxial compression strength, and elastic modulus of the anhydrite specimens decrease while the porosity and plasticity characteristics *** example, after 120 cycles, the uniaxial compression strength and elastic modulus decrease by 46.54% and 60.16%, and the porosity increase by 75%. Combined with the evolution trend of stressstrain curves and the detected events, three stages were labeled to investigate the AE characteristics in freeze-thaw weathered anhydrite rock. It is found that with the increase of freeze-thaw cycles, the proportions of AE counts in stage Ⅰ and stage Ⅱ show a decaying exponential trend. Contrarily, the proportion of AE counts in stage Ⅲ displays an exponential ascending trend. Meanwhile, as the freeze-thaw cycles increase, the low-frequency AE signals increase while the intermediate-frequency AE signals decrease. After 120 cycles, the proportion of low-frequency AE signals increases by 168.95%, and the proportion of intermediate-frequency AE signals reduces by 81.14%. It is concluded that the microtensile cracking events occupy a dominant position during the loading process. With the increase of freeze-thaw cycles, the b value of samples *** 120 cycles, b value decreases by 27.2%, which means that the proportion of cracking events in rocks with small amplitude decreases. Finally, it is proposed that the freeze-thaw damage mechanism of anhydrite is also characterized by the water chemical softening effect.

关键词： Freeze-thaw cycles Anhydrite rock Physical and mechanical properties AE characteristics Damage mechanism