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Transverse relaxation characteristic and stress relaxation model considering molecular chains of HTPB coating based on pre-strained thermal aging

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Defence Technology（防务技术） 2021年第3期17卷 821-828页

作者： Yong-qiang Du jian zheng Gui-bo Yu jian-zhuang Zhi Shijiazhuang Campus Army Engineering UniversityShijiazhuang050003China Intelligent Manufacturing Institute Hebei College of Industry and TechnologyShijiazhuang050003China

In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process,a one month thermal aging test was carried out at70C with pre-strain of 0%,3%,6%and 9%,*** low-field1 H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging *** stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain *** results showed that with the increase of aging time,the decay rate of transverse relaxation curve became faster,the transverse relaxation time decreased,the value of combined parameter q Mrl increased,the proportion of crosslinking chain decreased,while the proportion of dangling chain ***,the stress relaxation modulus increased,the crosslinking network structure of HTPB coating became denser and the degree of crosslinking *** the initial aging stage,the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain *** the increase of aging time,the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually *** correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950,which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.

关键词： HTPB Pre-strain aging Transverse relaxation characteristic Molecular chain Stress relaxation model

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Load laws of composite lining in mountain tunnel model tests and numerical simulation validation

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Journal of Mountain Science 2023年第7期20卷 2041-2057页

作者： ZHOU jian YANG Xin-an CHU zheng Department of Civil Engineering Hangzhou City UniversityHangzhou 310015China Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province Hangzhou City UniversityHangzhou 310015China The Key Laboratory of Road and Traffic Engineering Ministry of EducationTongji UniversityShanghai 201804China School of Information and Electrical Engineering Hangzhou City UniversityHangzhou 310015China

Currently,model tests are increasingly being used to simulate the construction of mountain tunnels,but the support structure of the model tests does not show the composite lining,and the force laws of the composite lining are not yet *** this research,the force variation of composite lining under three cases in model tests of deep-buried tunnels were carried out with the surrounding rock grade and installation time as the variation *** test results reveal that:(1)The suitable method to reduce the contact load between the secondary lining and primary support is to enhance the primary support in the soft and weak surrounding ***,for ClassⅢsurrounding rock and better quality of surrounding rock,the primary support can lag behind the excavation face a certain distance.(2)The axial forces of the bolts tend to rise with concentration of 0.4 kN-0.7 kN after the secondary lining was installed.(3)With or without two to three excavation cycles delayed,the load sharing ratio of the secondary lining of the Class III surrounding rock is less than 10%.Finally,the numerical simulation verifies the feasibility of the model tests.

关键词： Mountain tunnel Composite lining Surrounding rock grade Force variation Primary support Secondary lining

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A field study of advanced municipal wastewater treatment technology for artificial groundwater recharge

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Journal of Environmental Sciences 2006年第6期18卷 1056-1060页

作者： PI Yun-zheng WANG jian-long Laboratory of Environmental Technology Institute of Nuclear and New Energy Tsinghua University Beijing 100084 China

Field studies were conducted to investigate the advanced treatment of the municipal secondary effluent and a subsequent artificial groundwater recharge at Gaobeidian Wastewater Treatment Plant, Beijing. To improve the secondary effluent quality, the combined process of powdered activated carbon adsorption, flocculation and rapid sand filtration was applied, which could remove about 400 dissolved organic carbon （DOC） and 70% adsorbable organic halogens. The results of liquid size exclusion chromatography indicate that in the adsorption unit the removed organic fraction was mainly low molecular weight compounds. The fractions removed by the flocculation unit were polysaccharides and high molecular weight compounds. The retention of water in summer in the open recharge basins resulted in a growth of algae. Consequently, DOC increased in the polysaccharide and high molecular weight humic substances fraction. The majority of the DOC removal during soil passage took place in the unsaturated area. A limited reduction of DOC was observed in the aquifer zone.

关键词： artificial groundwater recharge soil aquifer treatment dissolved organic carbon

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A Numerical Approach to the Frequencies and Damping Rates of Ion-Acoustic Waves in Ion-Collisional Plasmas

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Chinese Physics Letters 1999年第12期16卷 905-907页

作者： zheng jian YU Chang-xuan Department of Modern Physics University of Science and Technology of ChinaHefei 230027

A numerical solution to the linearized ion Fokker-Planck equation is presented for large ionization-temperature ratio ZT_(e)/T_(i) ( ≥32). By reducing the equation to an eigenvalue problem through the moment approach, the frequencies and damping rates of ion-acoustic waves in ion-collisional plasmas are calculated as well as the specific heat ratios. Comparing our results with those calculated by Tracy et al. [Phys. Fluids, B5 (1993) 1430] shows that our method is accurate enough in large ZT_(e)/Ti plasmas.

关键词： equation eigenvalue linearized

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Aluminum-activated Oxalate Secretion does not Associate with Internal Content among Some Oxalate Accumulators

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Journal of Integrative Plant Biology 2008年第9期50卷 1103-1107页

作者： jian Li Yang LeiZhang Shao jian zheng State Key Laboratory of Plant Biochemistry and Physiology College of Life Sciences Zhejiang University Hangzhou 310058 China Department of Biology College of Food Science and Biotechnology Engineering Zhejiang Gongshang University Hangzhou 310035 China College of Environmental and Resource Sciences Zhejiang University Hangzhou 310029 China

Although aluminum （AI）-activated secretion of oxalate has been considered to be an important AI-exclusion mechanism, whether it is a general response in oxalate accumulators and related to oxalate content in roots are still not clear. Here, we examined the oxalate secretion and oxalate content in some oxalate accumulators, and investigated the role of oxalate secretion in AI resistance. When oxalate content in amaranth roots was decreased by about 50% with the increased ratio of NH4^＋-N to NO3^- -N in nutrient solution, the amount of AI-activated oxalate secretion still remained constant. There was no relationship between the content of the water soluble oxalate in four species of oxalate accumulators and the amount of the AI-activated oxalate secretion in roots. Furthermore, oxalate secretion is poorly associated with AI resistance among these species. Based on the above results, we concluded that although all of the oxalate accumulators tested could secrete oxalate rapidly, the density of anion channels in plasma membrane may play a more important role in AI-activated oxalate secretion.

关键词： aluminum toxicity Amaranthus anion channel oxalate accumulator oxalate secretion

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Spreading-rate dependence of hydroacoustic and teleseismic seismicity of ridge-transform systems:East Pacific Rise,Galapagos Ridge,and Mid-Atlantic Ridge

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Acta Oceanologica Sinica 2022年第5期41卷 124-135页

作者： Tingting zheng jian Lin Qiu Zhong Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyInnovation Academy of South China Sea Ecology and Environmental EngineeringChinese Academy of SciencesGuangzhou510301China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou511458China China-Pakistan Joint Research Center on Earth Sciences Chinese Academy of Science-Higher Education Commission(Pakistan)Islamabad45320Pakistan Department of Ocean Science and Engineering Southern University of Science and TechnologyShenzhen518055China Department of Geology and Geophysics Woods Hole Oceanographic InstitutionFalmouthWoods HoleMA02543USA

Seismicity in ocean ridge-transform systems reveals fundamental processes of mid-ocean ridges,while comparisons of seismicity in different oceans remain rare due to a lack of detection of small *** 1996 to 2003,the Pacific Marine Environmental Laboratory of the National Oceanic and Atmospheric Administration(NOAA/PMEL)deployed several hydrophones in the eastern Pacific Ocean and the northern Atlantic *** hydrophones recorded earthquakes with small magnitudes,providing us with opportunities to study the seismic characteristics of ridge-transform systems at different spreading rates and make further comparisons of their *** study comparatively analyzed hydroacoustic and teleseismic data recorded on the fast-spreading East Pacific Rise(EPR,10°S to 12°N),intermediate-spreading Galapagos Ridge(103°W to 80°W),and slow-spreading Mid-Atlantic Ridge(MAR,15°N to 37°N).We present a systematic study of the spatial and temporal distribution of events,aftershock seismicity,and possible triggering mechanisms of aftershock *** analysis yields the following conclusions.(1)From the hydroacoustic data,the EPR transform faults had the highest average seismicity rate among the three regions.(2)Along-ridge event distributions show that a high number of earthquakes were concentrated on the EPR,while they became dispersed on the GR and fewer and more scattered on the MAR,reflecting that the different tectonic origins were closely correlated with the spreading rate.(3)Analysis from mainshock-aftershock sequences shows no significant differences in the aftershock decay rate among the three regions.(4)Multiple types of aftershock triggering models were inferred from Coulomb stress changes:strike-slip mainshocks triggered strike-slip aftershocks and normal faulting aftershocks,and normal faulting mainshocks triggered normal faulting *** these results are case studies,they may be applicable to other ocean ridge-transform systems in future

关键词： East Pacific Rise Galapagos Ridge Mid-Atlantic Ridge hydroacoustic and teleseismic seismicity ridge-transform system

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Experimental study of the shrinkage behavior of cemented paste backfill

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第3期13卷 545-554页

作者： Jiahao Qin jian zheng Li Li Research Institute on Mines and the Environment(RIME UQAT-Polytechnique) Department of CivilGeological and Mining EngineeringÉcole Polytechnique de MontréalMontréalQuébecH3C 3A7Canada

Cemented paste backfill(CPB)is largely used in underground mine stopes *** a CPB is placed in a stope,an important task is to estimate the settlement associated with the shrinkage and selfweight consolidation of the *** is closely related to the volume management to ensure the stability of barricades and tight contacts between the backfill and stope *** the years,shrinkage studies were mostly performed on fine-grained soils(silts and clays),with only a few publications on the shrinkage behavior of uncemented *** study has been published on the shrinkage behavior of *** fill this gap,a series of shrinkage tests has been conducted on CPB with different cement contents,including zero cement content(uncemented paste backfill,uCPB).The results show that the shrinkage response of CPB is very different from that of *** a given initial water content,CPB exhibits a shorter normal shrinkage stage than *** unsaturation onset water content and void ratio,shrinkage limit and final void ratio of CPB are generally higher than those of *** a given cement content,the shrinkage behaviors of CPB and uCPB are significantly influenced by the initial water content.

关键词： Cemented paste backfill(CPB) Shrinkage Evaporation Underground mine stopes Volume variation

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Effects of Nb on microstructure and wear resistance of Fe-Cr-C-B surfacing alloy

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Journal of Iron and Steel Research International 2018年第2期25卷 243-251页

作者： jian Gou zheng-jun Liu Hua Jia Department of Material Science and Engineering ShenyangUniversity of Technology Shenyang 110870 LiaoningChina

The influence of Nb on the microstructure and wear resistance of the surfacing layer was investigated by using the Fe-based flux-cored wire in the Fe-Cr-C-B system. The microstructure, microhardness and wear resistance properties of the samples were investigated by X-ray diffraction, scanning electron microscopy, microhardness testing and abrasive wear testing, respectively. The results indicate that microstructures of the alloy are composed of martensite, retained austenite, M23（C,B）6 and NbC. Boride M23（C,B）6 is distributed along the grain boundaries, while NbC in shape-regular quadrilateral is distributed in martensite. The microhardness is distributed from the substrate to the surfacing layer gradiently. NbC significantly improved the wear resistance of surfacing layer.

关键词： Flux-cored wire Surfacing layer Microhardness Microstructure Wear resistance

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Upgraded control system designed for SECRAL

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Nuclear Science and Techniques 2017年第9期28卷 57-62页

作者： jian-Jun Su Yan-Yu Wang De-Tai Zhou Wen-Xiong Zhou jian-chuan Zhang Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000 China Chongqing University Chongqing 400044 China

To improve the accuracy and usability of the superconducting electron cyclotron resonance ion source with advanced design in Lanzhou(SECRAL), an upgraded version of the control system was designed and tested. This paper details the architecture of the optimized control system and presents the results of its use in the long-term operation of the accelerator. The control system software, based on Visual C++, was developed following the model-view-controller architecture design pattern. The data acquisition system was based on a field-programmable gate array integrated circuit. In addition, control strategies were optimized for higher operational stability. The upgraded control system was tested with a U^(33+) ion beam at SECRAL, where it provided a data acquisition time of less than 1 ms. The fast reaction time and highprecision data processing during beam tuning verified the stability and maintainability of the control system.

关键词：控制系统设计电子回旋共振离子源模型-视图-控制器现场可编程门阵列数据采集系统稳定性控制优化控制系统控制系统软件

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Comprehensive Evaluation of Large Infrastructure Project Plan with ANP

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Journal of China University of Mining and Technology 2005年第4期15卷 384-388页

作者： HAN chuan-feng CHEN jian-ye School of Economics and Management Tongji University Shanghai 200092 China

Analytic Network Process(ANP) was used in comprehensive evaluation of large infrastructure project plan. An model including social economy, ecological environment and resources was established with ANP method. The evaluation pattern of hierarchy structure and comprehensive evaluation method for quantity and quality of large infrastructure project were put forward, which provides an effective way to evaluate the large infrastructure project plan. Quantitative analysis indicated that the internal dependence relation of hierarchy structure has influence on ranking results of plan. It is suggested that considering the internal relation can helps managers make effective decisions.

关键词： analytic network process(ANP) decision science construction plan

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