检索结果-南通市图书馆

Hydrogeochemical Modeling of the Shallow Thermal Water Evolution in Yangbajing Geothermal Field, Tibet

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

Journal of Earth Science 2019年第4期30卷 870-878页

作者： Xiuhua zheng Chenyang duan Bairu Xia Yong Jiang Jian Wen School of Engineering and Technology China University of GeosciencesBeijing 100083China State Grid Lhasa Power Supply Company Lhasa 850000China Yangbajing Geothermal Power Station State Grid Tibet Electric Power Company LimitedLhasa 850000China

The exploitation of thermal water and the mix of cold water changed the properties of geofluid in shallow reservoir,which altered the concentration of the chemical constitutes and continuously built new water-rock reaction. This paper deduced reservoir pressure and temperature variation tendency from 2004 to 2013,analyzed the change of some components in the shallow reservoir water,and finally obtained the evolution of the shallow geothermal water with hydrogeochemical model. The results show the reservoir pressure decreased significantly compared with the slight decline of reservoir temperature,and much cold groundwater infiltrated into the shallow reservoir,which affected the solubility of SiO2 and led to precipitation,the increased CO2 in shallow reservoir promoted the dissolution of aluminosilicate. Calcite and kaolinite precipitation zone has extended to the north in the field,which influenced the porosity of the reservoir rock.

关键词： reservoir pressure and temperature component analysis hydrochemical modeling dissolution/precipitation

Effects of elevated ozone on growth and yield of field-grown rice in Yangtze River Delta,China

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2008年第3期20卷 320-325页

作者： CHEN Zhan WANG Xiaoke FENG Zhaozhong zheng Feixiang duan Xiaonan YANG Wenrui Research Center for Eco-Environmental Sciences Chinese Academy of Scienees Beijing 100085 China

With rapid industrialization and urbanization in the Yangtze Delta, China, the tropospheric ozone concentration has increased to levels that induce crop yield loss. Rice, a widely grown crop in China, was investigated in field-established, open-top chambers. Four treatments were used： charcoal-filtered air （CF）, non-charcoal-filtered air （NF）, and charcoal-filtered air with two levels of additional ozone （O3-1 and O3-2）. The AOT40s （accumulated hourly mean ozone concentration above 40 ppbv） were 0, 0.91, 23.24, and 39.28 ppmv.h for treatment of CE NF, O3-1, and O3-2, respectively. The rice height and biomass were reduced in the elevated ozone concentration. Less organic matter partitioning to roots under the elevated ozone significantly decreased rice root activity. The yield loss was 14.3% and 20.2% under O3-1 and O3-2 exposure, respectively. This was largely caused by a reduction in grain weight per panicle.

关键词： ozone rice growth yield Yangtze Delta

Effect of Tetrabutylammonium Bromide on Enzymatic Polymerization of Phenol Catalyzed by Horseradish Peroxidase

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2014年第7期32卷 906-913页

作者： Hua duan Ke zheng 崔元臣 Yu-dong Li Lei Zhang Key Laboratory of Ministry of Education for Special Functional Materials Henan University College of Chemistry and Chemical Engineering Henan University

In this article tetrabutylammonium bromide （TBAB） was first added in buffer to compose a convenient and environmentally friendly system, and enzymatic polymerization of phenol catalyzed by horseradish peroxidase （HRP） could proceed efficiently in this system. When TBAB was added, the most conversion of phenol could reach 99.1%. The phenol polymer was considered to consist of a mixture of phenylene （Ph） and oxyphenylene （Ox） units by IR analysis, and the ratio of phenylene to oxyphenylene units （Ph/Ox） was measured by titration. Moreover, the effects of the dosage of horseradish peroxidase （HRP） and pH value on the conversion of phenol were investigated. The reaction performed very effectively in this novel system when the addition of HRP was only 0.2 mg. In all cases, the weight-average molecular weight calculated by GPC-SLS was in a range from 12000 Da to 30000 Da. The phenol polymer prepared in the present research possessed good thermal stability shown by TG analysis.

关键词： Horseradish peroxidase Phenol Polymerization Tetrabutylammonium bromide.

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2015年第1期26卷 101-106页

作者： Huiquan zheng Hongjing duan Dehuo Hu Ruping Wei Yun Li Guangdong Academy of Forestry National Engineering Laboratory for Tree Breeding Beijing Forestry University

Chinese fir（Cunninghamia lanceolata（Lamb.）Hook） is one of the most important coniferous tree species used for timber production in China. Here, we conducted a sequence-related amplified polymorphism（SRAP） primer screening assay with a total of 594 primer combinations,using 22 forward and 27 reverse primers on four representative Chinese fir genotypes. The obtained results indicated that Chinese fir genomic DNA has a notable amplification bias on the employed forward or reverse primer nucleotides（30selection bases）. Out of the tested primer sets, 35 primer combinations with clearly distinguished bands, stable amplification, and rich polymorphism were selected and identified as optimal primer sets. These optimal primer pairs gave a total of 379 scorable bands,including 265 polymorphic bands, with an average of 10.8bands and 7.6 polymorphic bands per primer *** produced band number for each optimal primer set ranged from 7 to 14 with a percentage of polymorphic bands spanning from 33.3 to 100.0 %. These primer combinations could facilitate the next SRAP analysis assays in Chinese fir.

关键词： Chinese fir SRAP Primer Screening assay Polymorphism

Analysis of sand particles’ lift-off and incident velocities in wind-blown sand flux

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2013年第2期29卷 158-165页

作者： Tian-Li Bo Xiao-Jing zheng Shao-Zhen duan Yi-Rui Liang Key Laboratory of Mechanics on Western Disaster and Environment Department of MechanicsLanzhou University

In the research of windblown sand movement,the lift-off and incident velocities of saltating sand particles play a significant role in bridging the spatial and temporal scales from single sand particle＇s motion to windblown sand *** this paper,we achieved wind tunnel measurements of the movement of sand particles near sand bed through improving the wind tunnel experimental scheme of paticle image velocimetry（PIV） and data processing *** then the influence of observation height on the probability distributions of lift-off and incident velocities of sand particles was *** results demonstrate that the observation height has no obvious influence on the distribution pattern of the lift-off and incident velocities of sand particles,i.e.,the probability distribution of horizontal and vertical velocities of lift-off and incident sand particles follow a Gaussian distribution and a negative exponential distribution,***,it influences the center of the Gaussian distribution,the decay constant and the amplitude of the negative exponential distribution.

关键词： Probability distribution·Sand particles' horizontal velocities·Sand particles' vertical velocities·Center of the Gaussian distribution·Decay constant of the negative exponential distribution

Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengthes

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2011年第5期27卷 778-784页

作者： zheng duan Xian-Feng Ma Hui-Ji Shi Ryosuke Murai Eiichi Yanagisawa AML DepartmentofEngineeringMechanicsSchoolofAerospaceTsinghuaUniversity100084BeijingChinaAML Department of Engineering MechanicsSchool of Aerospace Tsinghua University100084 Beijing China Mitsubishi Heavy Industries Ltd. Tokyo Japan

Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengthes were experimentally studied by rotating bending tests,to investigate the effects of the tensile strength obtained by different heat treatment processes on very high cycle fatigue failure *** material with higher tensile strength of 1 710 MPa exhibited typical gigacycle fatigue failure characteristics,whereas one with lower tensile strength of 1 010 MPa showed only traditional fatigue limit during the tests and no gigacycle failure could be found even when the specimen ran up to more than 10 8 *** and fractographic analysis were carried out by an optical microscope （OM） and scanning electron microscope （SEM）.It showed two different crack initiation mechanisms that for the specimen with lower tensile strength the crack prefers surface initiation and for that with higher strength the crack initiates from subsurface inclusions revealed by a fish-eye like microstructure.

关键词： Gigacycle fatigue · S-N curves · Crack initiation · Fractography

Statistics of Polymer Capture by a Nanopore:A Brownian Dynamics Simulation Study

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2015年第5期33卷 674-679页

作者： Ming-ming Ding Xiao-zheng duan 卢宇源石彤非 State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of Sciences

We investigate the statistics of polymer capture by a nanopore using Brownian dynamics simulations. It is found that when the velocity flux is greater than a critical velocity flux, the capture picture is a random selection process, otherwise it tends to a statistical process governed by energetic considerations. In addition, the chain ends capture probability decreases as the chain length increases and satisfies a power-law scaling of P0（N）-N^-0.8.

关键词： Polymer capture Critical velocity flux Brownian dynamics

Dynamics of firing patterns,synchronization and resonances in neuronal electrical activities:experiments and analysis

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2008年第6期24卷 593-628页

作者： Qishao Lu Huaguang Gu Zhuoqin Yang Xia Shi Lixia duan Yanhong zheng School of Science. Beihang University 100191 Beijing China School of Science Beijing University of Posts and Telecommunications 100876 Beijing China College of Science. North China University of Technology 100144 Beijing China School of Mathematics and Computer Science Fujian Normal University Fuzhou 350007. China

Recent advances in the experimental and theoretical study of dynamics of neuronal electrical firing activities are reviewed. Firstly, some experimental phenomena of neuronal irregular firing patterns, especially chaotic and stochastic firing patterns, are presented, and practical nonlinear time analysis methods are introduced to distinguish deterministic and stochastic mechanism in time series. Secondly, the dynamics of electrical firing activities in a single neuron is concerned, namely, fast-slow dynamics analysis for classification and mechanism of various bursting patterns, one- or two-parameter bifurcation analysis for transitions of firing patterns, and stochastic dynamics of firing activities （stochastic and coherence resonances, integer multiple and other firing patterns induced by noise, etc.）. Thirdly, different types of synchronization of coupled neurons with electrical and chemical synapses are discussed. As noise and time delay are inevitable in nervous systems, it is found that noise and time delay may induce or enhance synchronization and change firing patterns of coupled neurons. Noise-induced resonance and spatiotemporal patterns in coupled neuronal networks are also demonstrated. Finally, some prospects are presented for future research. In consequence, the idea and methods of nonlinear dynamics are of great significance in exploration of dynamic processes and physiological functions of nervous systems.

关键词： Neuron Firing patterns Synchronization Resonance Noise

Fatigue and fracture behavior of nickel-based superalloy Inconel 718 up to the very high cycle regime

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) 2010年第10期11卷 727-737页

作者： Xian-feng MA zheng duan Hui-ji SHI Ryosuke MURAI Eiichi YANAGISAWA Applied Mechanics Laboratory Department of Engineering Mechanics School of Aerospace Tsinghua University Beijing 100084 China Mitsubishi Heavy Industries Ltd. Tokyo Japan

The fatigue and fracture behavior of nickel-based superalloy Inconel 718 was investigated up to the very high cycle regime under rotary bending tests at room temperature. It was found that this superalloy can still fracture after exceeding 107 cycles. Fractographic analysis revealed that there was a transition from fatigue crack initiation at multi-sites to single initiation with decreasing stress levels. The fracture surface can be divided into four areas according to the appearance, associated with fracture mechanics analysis of the corresponding stress intensity factors. The fracture mechanism dominant in each area was disclosed by scanning electron microscope examination and analyzed in comparison with those obtained from the crack growth tests. Subsequently, life prediction modeling was proposed by estimating the crack initiation and propagation stage respectively. It was found that Chan (2003)'s model for initiation life and the Paris law for growth life can provide comparable predictions against the experimental life.

关键词： Nickel-based superalloy High cycle fatigue (HCF) Fatigue crack initiation Crack growth Life prediction