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Formation estimation and evolution mechanism of the pressure arch for non-circular tunnels under asymmetrical stress field

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Science China(Technological Sciences) 2024年第9期67卷 2919-2938页

作者： SUN ZhenYu ZHANG DingLi xu tong CHEN xu Key Laboratory for Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

The tunneling-induced stress redistribution is dependent on the tunnel shape and the in-situ stress field, and the previous arch characterization method based on the circumferential or maximum principal stresses is only suitable for the circular tunnels under the hydrostatic stress field. In this study, a unified characterization method of the pressure arch for non-circular tunnels under the arbitrary stress field is proposed. By comparing the variations of compressive stress in different directions due to excavation, the ratio of the most significant increase in compressive stress is presented to characterize the arch effect, and the corresponding numerical algorithm is given. Since the proposed method takes the stress element as the basic analytical model, it can be easily applied to various complex excavation situations. Thereafter, combined with the established folding catastrophic model, an objective and unified quantitative method of the pressure arch boundaries is given. Using the proposed method, the longitudinal evolution of the pressure arch is analyzed. According to the expansion rate of the arch boundaries, three evolution stages including the initial formation, rapid expansion and stabilization are categorized. Parametric studies are conducted to illustrate the effect of ground properties and support stiffness on the pressure arch formation. It is found that the ground strength parameters and burial depth affect the arch range at a decreasing rate, while they have little effect on the arch shape. The lateral pressure coefficient has a significant effect on both the shape and range of the pressure arch. Increasing the support stiffness helps reduce the pressure arch range with a decreasing rate, while the synchronous variation of the elastic moduli of the surrounding rock and support does not affect the arch range under a certain relative elastic modulus. Finally, field monitoring is conducted to validate the proposed method in actual support design.

关键词： pressure arch stress redistribution numerical simulation quantitative characterization longitudinal evolution parametric study

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Water Dissociation Phenomena on a Bipolar Membrane──Current-voltage Curve in Relation with IonicTransport and Limiting Current Density

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Chemical Research in Chinese Universities 2001年第4期17卷 457-464页

作者： xu tong-wen YANG Wei-hua Department of Applied Chemistry University of Science and Technology of ChinaHefei 230026P.R.China

The water dissociation mechanism on a bipolar membrane under the electrical field was investigated and characterized in terms of ionic transport and limiting current density. It is considered that the depletion layer exists at the junction of a bipolar membrane, which is coincided with the viewpoint of the most literatures, but we also consider that the thickness and conductivity of this layer is not only related with the increase of the applied voltage but also with the limiting current density. Below the limiting current density, the thickness of the depletion layer keeps a constant and the conductivity decreases with the increase of the applied voltage; while above the limiting current density, the depletion thickness will increase with the increase of the applied voltage and the conductivity keeps a very low constant. Based on the data reported in the literatures and independent determinations, the limiting current density was calculated and the experimental curves Ⅰ-Ⅴ in the two directions were com

关键词： Bipolar membrane Water dissociation Ionic transport Limiting current density

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αB-crystallin malondialdehyde,superoxide dismutase, and lutathione peroxidase changes in X-ray irradiated rat lens

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International Journal of Ophthalmology(English edition) 2011年第4期4卷 365-370页

作者： Guo-xu xu, Guo-tong xu Department of Ophthalmology the Second Hospital of Soochow University Suzhou 215004 Jiangsu Province China tongji Eye Institute and Department of Regenerative Medicine Tongji University School of Medicine Shanghai 200092 China

AIM: To evaluate αB-crystallin malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPx) changes in X-ray irradiated rat lens. METHODS: Eight-week-old Sprague-Dawley male rats received X-ray irradiation to the head with rest of the body protected. The exposure dose ranged from 2 to 25 Grays (Gy). The cataract status were examined by slit lamp and rated with 'four-grade systems' post-irradiation. The lens MDA level, and the activities of SOD and GPx were measured in a short-term experiment post-irradiation, and αB-crystallin protein levels were quantified. RESULTS: The lenses of normal control and the X-ray irradiated groups with the dose up to 10 Gy remained transparent throughout the experiment. The lens first appeared tiny scatters, and even lamellar opacities in the posterior capsule 45 days post-irradiation with the dose of 15 Gy, and progressed slowly to the advance stage of cataract; while, for the higher dose (25 Gy), the opacity of lens appeared much earlier, and progressed more rapidly to mature stage of cataract within 1 month. At the end of the observation (90 days post-irradiation), almost all lenses became complete opacity with the higher dose (25 Gy). The degree of lens opacity was rated accordingly. The lens MDA level was increased, and SOD and GPx activities were decreased with a dose-dependent manner post-irradiation. The αB-crystallin protein level was decreased dose-dependently at the end point of observation. CONCLUSION: Oxidative events and αB-crystallin may play important roles in the pathogenesis of cataract in X-ray irradiated rat lens.

关键词： αB-crystallin malondialdehyde superoxide dismutase glutathione peroxidase X-ray irradiation cataract

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Influence of Fill Point in Multiple-Heat-Sources Looped District Heating System with Distributed Variable-Speed Pumps

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Journal of Thermal Science 2020年第5期29卷 1206-1222页

作者： xu tong YAN Jing WANG Xinlei WANG Hai ZHU tong WANG Haiying Beijing Huajian Power Design and Research Institute Beijing 101400China School of Mechanical Enginecring Tongji UniversityShanghai 200092China

When regulating a pipe network according to user demand,hydraulic balance and power consumption are crucial factors for a multi-source looped-pipe network applying distributed variable-speed pumps compared to the conventional central circulating pump *** this paper,the influence of the fill point on power consumption and hydraulic balance of the multi-source looped-pipe network was studied.A mathematical model for electricity energy consumption analysis was built and calculated for a large sized looped-pipe network with multiple heat sources and distributed variable-speed *** hydraulic calculation models of each single element,such as pipe,distribution pump,valve,replenishment pump,heat source and substation,were built.A case located in Dezhou city,China was *** results showed that:the maximum power saving(39.2%)could be achieved when each heat source had its own fill point,but the heat sources would not meet their design flows;to meet the design flows of all the heat sources,only one fill point should be necessarily located near the heat source with the lowest flow rate to get the expected hydraulic stability and energy saving.

关键词： district heating central circulating pump distributed variable-speed pumps fill point energy saving

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Prevalence of Falls Among the Rural Elderly-Three PLADs of Western China, 2017–2018

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China CDC weekly 2020年第46期2卷 877-880页

作者： tong xu Hui Han National Center for Women and Children’s Health Chinese Center for Disease Control and PreventionBeijingChina

Summary What is already known about this topic?As population aging becomes serious in China,the elderly health problems stand out *** of falls of the elderly has become an important subject in China’s public health.

关键词： Rural Elderly elderly

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Analysis of Stock Splits Based on Risk Theory: Empirical Evidence from the Chinese Stock Markets

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Journal of Systems Science and Information 2022年第1期10卷 19-34页

作者： Shujin WU tong xu MOE Key Laboratory of Advanced Theory and Application in Statistics and Data Science School of StatisticsEast China Normal UniversityShanghai 200062China School of Statistics East China Normal UniversityShanghai 200062China

The paper first analyzes price change due to stock splits in Chinese stock markets,which shows stock prices typically go up for stock *** theoretical analyses based on risk theory are presented to explain the reason,where the method comes from a new perspective and obtained theoretical conclusions show that stock splits typically make stock price go up if risk-compensation function is convex,and go down if risk-compensation function is *** prices typically go up for stock splits because risk-compensation functions are mainly *** obtained conclusions are consistent with the known results in the last three decades.

关键词： stock split risk theory price Chinese stock markets

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Two-Week Prevalence of Disease Among the Rural Elderly--6 Provinces,China,2018−2019

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China CDC weekly 2020年第38期2卷 736-739页

作者： tong xu Hui Han National Center for Women and Children’s Health Chinese Center for Disease Control and PreventionBeijingChina.

What is already known about this topic?As population aging becomes serious in China,the elderly health problems stand out *** 2-week prevalence of the elderly is rising year by year,but it has been rarely studied for the rural seniors in the central and western *** is added by this report?The 2-week prevalence rate of rural elderly in the central and western China is 28.5%,and it varies among different ethnic *** top prevalence is chronic diseases,and the severity of diseases is higher in female and high age group(80-year-old and over)*** are the implications for public health practice?Considering the health status,health awareness and ethnic differences of the elderly in the central and western China,medical and health resources should be rationally allocated to prevent and treat chronic diseases and support differentiated health *** is of great significance for the development of health service plan.

关键词： prevalence diseases Rural

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Enhanced CO2 Electrolysis with Metal-oxide Interface Structures

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Chinese Journal of Structural Chemistry 2021年第1期40卷 31-41,1页

作者： xu Ze-tong XIE Kui College of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350007China CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China

The ever-decreasing fossil fuels and the increasing greenhouse effect have caused substantial *** oxide electrolyser cell(SOEC)with La_(0.75)Sr_(0.25)Cr_(0.5 )Mn_(0.5)O_(3-δ)(LSCM)as a cathode was used for CO_(2) electrolysis to *** this work,the metal-oxide interface was constructed on the LSCM framework by in-situ exsolution and impregnation,and the uniform distribution of metal nanoparticles on the LSCM framework was confirmed by spectroscopy techniques and electron microscopy *** existence of three-phase boundary promoted the absorption and electrolysis of CO_(2).(La_(0.75) Sr_(0.25))0.9(Cr_(0.5 )Mn_(0.5))_(0.9)(Ni_(0.5) Cu_(0.5))_(0.1) O_(3-δ)(LSCMNC)showed the best electrolytic CO_(2) performance at 850℃and exhibited excellent electrocatalytic activity after 100 hours of long-term testing and 8 redox cycles.

关键词： solid oxide electrolyser cell LSCM metal nanoparticles CO_(2)electrolysis

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Inflammation in diabetic retinopathy: possible roles in pathogenesis and potential implications for therapy

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Neural Regeneration Research 2023年第5期18卷 976-982页

作者： Lei Tang Guo-tong xu Jing-Fa Zhang Department of Ophthalmology of tongji Hospital Tongji Eye InstituteDepartment of Regenerative Medicineand Department of PharmacologyTongji University School of MedicineShanghaiChina Department of Ophthalmology Shanghai General Hospital(Shanghai First People’s Hospital)Shanghai Jiao Tong UniversityShanghaiChina National Clinical Research Center for Eye Diseases Shanghai Key Laboratory of Ocular Fundus DiseasesShanghai Engineering Center for Visual Science and PhotomedicineShanghai Engineering Center for Precise Diagnosis and Treatment of Eye DiseasesShanghaiChina

Diabetic retinopathy, characterized as a microangiopathy and neurodegenerative disease, is the leading cause of visual impairment in diabetic patients. Many clinical features observed in diabetic retinopathy, such as capillary occlusion, acellular capillaries and retinal non-perfusion, aggregate retinal ischemia and represent relatively late events in diabetic retinopathy. In fact, retinal microvascular injury is an early event in diabetic retinopathy involving multiple biochemical alterations, and is manifested by changes to the retinal neurovascular unit and its cellular components. Currently, intravitreal anti-vascular endothelial growth factor therapy is the firstline treatment for diabetic macular edema, and benefits the patient by decreasing the edema and improving visual acuity. However, a significant proportion of patients respond poorly to anti-vascular endothelial growth factor treatments, indicating that factors other than vascular endothelial growth factor are involved in the pathogenesis of diabetic macular edema. Accumulating evidence confirms that low-grade inflammation plays a critical role in the pathogenesis and development of diabetic retinopathy as multiple inflammatory factors, such as interleukin-1β, monocyte chemotactic protein-1 and tumor necrosis factor-α, are increased in the vitreous and retina of diabetic retinopathy patients. These inflammatory factors, together with growth factors such as vascular endothelial growth factor, contribute to blood-retinal barrier breakdown, vascular damage and neuroinflammation, as well as pathological angiogenesis in diabetic retinopathy, complicated by diabetic macular edema and proliferative diabetic retinopathy. In addition, retinal cell types including microglia, Müller glia, astrocytes, retinal pigment epithelial cells, and others are activated, to secrete inflammatory mediators, aggravating cell apoptosis and subsequent vascular leakage. New therapies, targeting these inflammatory molecules or relate

关键词： anti-inflammation therapy anti-vascular endothelial growth factor diabetic retinopathy hyperreflectivity foci inflammation inflammatory cells inflammatory cytokines leukostasis microglia Müller cells

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Data-driven Inverter-based Volt/VAr Control for Partially Observable Distribution Networks

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CSEE Journal of Power and Energy Systems 2023年第2期9卷 548-560页

作者： tong xu Wenchuan Wu Yiwen Hong Junjie Yu Fazhong Zhang Southwest Electric Power Design Institute Co. Ltd.of China Power Engineering Consulting GroupChengduSichuan 610021China Tsinghua University Beijing 100084China Department of Electrical Engineering State Key Laboratory of Power SystemsTsinghua UniversityBeijing 100084China Guangdong Power Grid Zhongshan Power Supply Bureau Zhongshan 528400China

For active distribution networks(ADNs)integrated with massive inverter-based energy resources,it is impractical to maintain the accurate model and deploy measurements at all nodes due to the large-scale of ***,current models of ADNs usually involve significant errors or even unknown ***,ADNs are usually partially observable since only a few measurements are available at pilot nodes or nodes with significant *** provide a practical Volt/Var control(VVC)strategy for such networks,a data-driven VVC method is proposed in this ***,the system response policy,approximating the relationship between the control variables and states of monitoring nodes,is estimated by a recursive regression closed-form ***,based on real-time measurements and the newly updated system response policy,a VVC strategy with convergence guarantee is *** the recursive regression solution is embedded in the control stage,a data-driven closedloop VVC framework is *** effectiveness of the proposed method is validated in an unbalanced distribution system considering nonlinear loads,where not only the rapid and self-adaptive voltage regulation is realized,but also systemwide optimization is achieved.

关键词： Data-driven distribution networks partial observation Volt/VAr control

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