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Flexibility Improvement of CHP Unit for Wind Power Accommodation

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Journal of Modern Power Systems and Clean Energy 2022年第3期10卷 731-742页

作者： dongming zhang Yong Hu Yaokui Gao School of Control and Computer Engineering North China Electric Power UniversityBeijingChina

Improving the flexibility of combined heat and power(CHP)units is an important way to solve the problem of wind power accommodation in northern ***,this paper analyzes the principle of an extraction-type CHP unit,calculates its safe operation range,and analyzes its contradiction between heating and ***,the safe operation ranges of the CHP unit with several flexibility modifications are further calculated,which involve two-stage bypass,low-pressure cylinder(LPC)removal,heat storage tank,and electric ***,based on the safe operation ranges,their effects on improving the capabilities of deep peak shaving and wind power accommodation are compared,and their adaptabilities to different wind scenarios are *** results show that:①all flexibility modifications can improve the deep peak shaving capability of the CHP unit,especially for the two-stage bypass and the electric boiler;②LPC removal modification can accommodate wind power to some extent,but most of wind power is still abandoned;③heat storage tank modification is unstable in different wind scenarios,which is determined by the surplus heating capability during the daytime.

关键词： Combined heat and power(CHP) flexibility bypass low-pressure cylinder(LPC)removal heat storage tank electric boiler

Failure responses of rock tunnel faces during excavation through the fault-fracture zone

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Underground Space 2023年第3期10卷 166-181页

作者： Zeyu Li Hongwei Huang Mingliang Zhou dongming zhang Department of Geotechnical Engineering Tongji UniversitySiping Road 1239Shanghai 200092China

It is essential to cast light on the construction risks in tunnel excavations through the fault-fracture zone(FFZ).This study adopts the material point method(MPM)to simulate the failure responses of a rock tunnel face during excavation through the FFZ.A numerical study was conducted to compare a physical model test and validate the feasibility of using the MPM in simulating tunnel face *** hundred ninety numerical simulation cases were constructed to represent a rock tunnel excavation project with different site *** simulation results suggest that the cohesion and the friction angle significantly influence failure *** tunnel cover depth can magnify the failure responses,and the FFZ thickness significantly affects the mobilized rock mass volume when the FFZ consists of a weak rock *** numerical simulation results suggest three deformation patterns:face bulge,partial failure,and slide *** failure responses can be characterized by stress arch,slip surface,angle of reposing,and influence *** insights suggested by the face failure responses during excavation through the FFZ can aid field engineers in determining the scope of possible damage,and in establishing emergency measures to minimize losses if such failure occurs.

关键词： Tunnel face failure Rock tunnel excavation Large deformation Fracture fault zone Material point method

Horizontal convergence reconstruction in the longitudinal direction for shield tunnels based on conditional random field

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Underground Space 2023年第3期10卷 118-136页

作者： Jingkang Shi Fei Wang Hongwei Huang dongming zhang Department of Geotechnical Engineering Tongji UniversityShanghai 200092China Shanghai Institute of Disaster Prevention and Relief Tongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering of Minister of Education Tongji UniversityShanghai 200092China

Tunnel horizontal convergence monitoring is essential to ensure the operation ***,only a few representative tunnel sec-tions are chosen for monitoring due to the cost *** is difficult to capture the horizontal convergence of each tunnel ring with limited *** with this difficulty,the paper proposes a horizontal convergence reconstruction method based on the measurements of deployed *** tunnel horizontal convergence along the longitudinal direction is seen as a one-dimensional sta-tionary and ergodic random *** reconstruction problem is then transformed into the generation of conditional random *** Carlo simulation is adopted to generate possible realizations and the mean of realizations is considered as the maximum likeli-hood *** analysis proves the effectiveness of the proposed reconstruction *** proposed method is proved to be applicable in reconstructing the time-variant horizontal convergence and is verified by the monitoring results of the shield tunnel of Shanghai Metro Line *** effect of sensor numbers is parametrically studied,and an optimal sensor placement scheme is *** sensors placed at the deformation drastically changed location can significantly improve the performance of the proposed method.

关键词： Structural performance reconstruction Tunnel convergence monitoring Conditional random field Optimal sensor placement

Acquisition of functional neurons by direct conversion:Switching the developmental clock directly

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Journal of Genetics and Genomics 2019年第10期46卷 459-465页

作者： Shuangquan Chen Juan zhang dongming zhang Jianwei Jiao Institute of Zoology Chinese Academy of SciencesBeijing100101China School of Pharmaceutical Sciences Tsinghua UniversityBeijing100084China University of Chinese Academy of Sciences Beijing100049China Co-Innovation Center of Neuroregeneration Nantong UniversityNantong226001China Institute for Stem Cell and Regeneration Chinese Academy of SciencesBeijing100101China

Identifying approaches for treating neurodegeneration is a thorny task but is important for a growing number of *** have focused on discovering the underlying molecular mechanisms of reprogramming and optimizing the technologies for acquiring *** conversion is one of the most important processes for treating neurological *** neurons derived from direct conversion,which bypass the pluripotency stage,are more effective,more quickly obtained,and are safer than those produced via induced pluripotent stem cells(iPSCs).Based on iPSC strategies,scientists have derived methods to obtain functional neurons by direct conversion,such as neuron-related transcriptional factors,small ***,and epigenetic *** this review,we discuss the present strategies for direct conversion of somatic cells into functional neurons and the potentials of direct conversion for producing functional neurons and treating neurodeeeneration.

关键词： Direct conversion Fibroblasts Induced neurons Neurodegeneration

Microstructural and thermal properties of coal measure sandstone subjected to high temperatures

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 2909-2921页

作者： Weijing Xiao dongming zhang Shujian Li Mingyang Wu School of Civil Engineering and Architecture East China Jiaotong UniversityNanchang330013China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400044China Yunnan Phosphate Chemical Group Co. Ltd.Kunming650600China National Engineering and Technology Research Center for Development and Utilization of Phosphate Resources Kunming650600China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

To study the microscopic structure,thermal and mechanical properties of sandstones under the influence of temperature,coal measure sandstones from Southwest China are adopted as the research object to carry out high-temperature tests at 25℃-1000℃.The microscopic images of sandstone after thermal treatment are obtained by means of polarizing microscopy and scanning electron microscopy(SEM).Based on thermogravimetric(TG)analysis and differential scanning calorimetric(DSC)analysis,the model function of coal measure sandstone is explored through thermal analysis kinetics(TAK)theory,and the kinetic parameters of thermal decomposition and the thermal decomposition reaction rate of rock are *** the uniaxial compression experiments,the stress‒strain curves and strength characteristics of sandstone under the influence of temperature are *** results show that the temperature has a significant effect on the microstructure,mineral composition and mechanical properties of *** particular,when the temperature exceeds 400℃,the thermal fracture phenomenon of rock is obvious,the activity of activated molecules is significantly enhanced,and the kinetic phenomenon of the thermal decomposition reaction of rock appears *** mechanical properties of rock are weakened under the influence of rock thermal fracture and mineral thermal *** research results can provide a reference for the analysis of surrounding rock stability and the control of disasters caused by thermal damage in areas such as underground coal gasification(UCG)channels and rock masses subjected to mine fires.

关键词： Rock mechanics Coal measure sandstone Micromorphology Thermal damage

Phase component and microstructure of laser-sintered Mg-Ni alloys

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Rare Metals 2008年第4期27卷 400-404页

作者： SI Tingzhi Li Yongtao LIU dongming zhang Qing＇an School of Materials Science and Engineering Anhui University of Technology Maanshan 243002 China

The Mg-Ni hydrogen storage alloys were prepared using the laser sintering technology. The effects of laser sintering power on the phase component and the weight loss of Mg element for the Mg-Ni alloys were investigated. The samples P1, P2 and P3 consisted of five phases： Mg2Ni, MgNi2, Mg, Ni and MgO. The weight loss of Mg element remarkably increased at 1200 W. The addition of extra Mg significantly promoted the reaction between Mg and Ni. Mg2Ni, MgNi2, and a small amount of Ni and MgO phases were present in the samples PM （pestie milling） and BM （ball milling）. The sample PM has a homogeneous microstructure, and the contents of Mg2Ni and MgNi2 were approximately consistent with those of the Mg-Ni alloy under the equilibrium conditions. The maximum hydrogen storage capacity of the sample BM was 1.72 wt.% and the sample can be activated easily at 573 K （only 3 activation cycles）.

关键词： hydrogen storage alloys phase structure laser sintering hydrogen storage property

Comparative experimental study on porosity, mechanical and CO_(2) adsorption characteristics of coal and shale

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Frontiers of Earth Science 2023年第3期17卷 788-796页

作者： Haitao LI Guo YU Xiaolei WANG dongming zhang Exploration and Development Research Institute of PetroChina Southwest Oil and Gas Field CompanyChengdu 610051China PetroChina Southwest Oil and Gas Field Company Planning Department Chengdu 610051China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China School of Resources and Environmental Engineering Jiangxi University of Science and TechnologyGanzhou 341000China

To compare the pore structure, mechanical and CO_(2) adsorption properties of coal and shale, a series of experiments were carried out using nuclear magnetic resonance (NMR), uniaxial compression, Brazilian splitting, and high-pressure CO_(2) adsorption. The results show that the total porosity of coal is 7.51 times that of shale, and shale is dominated by adsorption pores, while adsorption pores and seepage pores in coal are equally important. Moreover, it is found that the micropores in shale are more advantageous, while meso-macropore in coal are more significant. The adsorption pore surface of coal is rougher than that of shale, and the seepage pore structure of shale is more complex. The uniaxial compressive strength, elastic modulus and absorption energy of shale are 2.01 times, 2.85 times, and 1.27 times that of coal, respectively, indicating that shale has higher compressive capacity and resistance to elastic deformation than coal. The average tensile strength, Brazilian splitting modulus, absorbed energy and brittleness index of shale are 7.92 times, 6.68 times, 10.78 times, and 4.37 times that of coal, respectively, indicating that shale has higher tensile strength and brittleness, but lower ductility, compared with coal. The performed analyses show that under the same conditions, the CO_(2) adsorption capacity of coal is greater than that of shale. The present article can provide a theoretical basis to implement CO_(2)-enhanced coalbed methane (CBM)/shale gas extraction.

关键词： coal shale NMR mechanical properties adsorption characteristic

A hybrid attention deep learning network for refined segmentation of cracks from shield tunnel lining images

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3105-3117页

作者： Shuai Zhao Guokai zhang dongming zhang Daoyuan Tan Hongwei Huang Department of Civil and Environmental Engineering The Hong Kong Polytechnic University999077Hong KongChina School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai200093China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai200092China

This research developed a hybrid position-channel network (named PCNet) through incorporating newly designed channel and position attention modules into U-Net to alleviate the crack discontinuity problem in channel and spatial dimensions. In PCNet, the U-Net is used as a baseline to extract informative spatial and channel-wise features from shield tunnel lining crack images. A channel and a position attention module are designed and embedded after each convolution layer of U-Net to model the feature interdependencies in channel and spatial dimensions. These attention modules can make the U-Net adaptively integrate local crack features with their global dependencies. Experiments were conducted utilizing the dataset based on the images from Shanghai metro shield tunnels. The results validate the effectiveness of the designed channel and position attention modules, since they can individually increase balanced accuracy (BA) by 11.25% and 12.95%, intersection over union (IoU) by 10.79% and 11.83%, and F1 score by 9.96% and 10.63%, respectively. In comparison with the state-of-the-art models (i.e. LinkNet, PSPNet, U-Net, PANet, and Mask R–CNN) on the testing dataset, the proposed PCNet outperforms others with an improvement of BA, IoU, and F1 score owing to the implementation of the channel and position attention modules. These evaluation metrics indicate that the proposed PCNet presents refined crack segmentation with improved performance and is a practicable approach to segment shield tunnel lining cracks in field practice.

关键词： Crack segmentation Crack disjoint problem U-net Channel attention Position attention

Pore structure characterization and seepage analysis of ionic rare earth orebodies based on computed tomography images

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International Journal of Mining Science and Technology 2022年第2期32卷 411-421页

作者： Xianping Luo Yongbing zhang Hepeng Zhou Kunzhong He Boyuan zhang dongming zhang Weijing Xiao National Innovation Center for Rare Earth Functional Material Jiangxi University of Science and TechnologyGanzhou 341000China Key Laboratory of Ionic Rare Earth Resources Development and Application Ministry of EducationJiangxi University of Science and TechnologyGanzhou 341000China Jiangxi Key Laboratory of Mining&Metallurgy Environmental Pollution Control Jiangxi University of Science and TechnologyGanzhou 341000China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China

Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on *** ore body structure,pore distribution,pore and throat size,and pore network characteristics of topsoil,weathered,and semiweathered layers of ionic rare earth ore in southern Jiangxi Province were explored in this *** effect of leaching operation on the pore structure was investigated,and main factors affecting the seepage were *** showed that the semiweathered layer presents a dense structure and a small number of unconnected *** of topsoil and weathered layers are mainly long and narrow column openings with some planar *** pore distribution and large size span were *** with the weathered layer,the topsoil layer demonstrates larger voids,smaller average pore volume and equivalent radius,and fewer coordination throats;however,the average equivalent radius of the throat in the topsoil layer is larger and largescale channels exist through ore body ***,permeability of the topsoil layer is significantly higher than that of the weathered *** clay minerals migrate easily and the occurrence of silting in the small porosity blocks the throat and significantly decreases the permeability of the ore body in the leaching *** equivalent radius of the throat is the key to the *** the migration of fine particles is an effective measure to protect the throat and shorten the leaching period.

关键词： Ionic rare earth ore CT scanning 3D visualization Pore characteristics Permeability