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Surrounding rock pressure in the tunnel portal section through moraine under freeze-thaw action

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Journal of Mountain Science 2024年第7期21卷 2480-2493页

作者： CHEN Zhimin LIU Baoli LIU Yaohui xu jiangtao School of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730070China CSCEC AECOM Consultants Co. ltdLanzhou 730000China National and Local Joint Engineering Laboratory of Road and Bridge Engineering Disaster Prevention Technology Lanzhou Jiaotong UniversityLanzhou 730070China

Moraines,characterized by the accumulation of rock and soil debris transported by glacial activity,present unique challenges for tunnel construction,particularly in portal sections,due to prevailing geographical and climatic conditions that facilitate freeze-thaw *** these challenges,there is a dearth of studies investigating the influence of freeze-thaw action and water content on the mechanical properties of moraines,and no research on calculating surrounding rock pressure in moraine tunnels subjected to freeze-thaw *** this study,direct shear tests under freeze-thaw cycles were conducted to examine the effects of freeze-thaw cycles and water content on the mechanical properties of frozen moraine.A comprehensive parameter K,integrating the number of freeze-thaws and water content,was introduced to model cohesion *** on Terzaghi Theory,we propose an improved algorithm for calculating surrounding rock pressure at the portal section of moraine *** a tunnel as a case study,surrounding rock pressure was calculated under various conditions to validate the Improved Algorithm's *** results show that:(1)Strength loss exhibits a linear trend with the number of freeze-thaw cycles at water content levels of 4%and 8%,while at 12%water content,previous freeze-thaw cycles induce more significant damage to the soil.(2)Moraine saturation peaks between 8%and 12%water *** repeated freeze-thaw cycles,moraine shear strength initially increases before decreasing with varying water content.(3)The internal friction angle of moraine experiences slight reductions with prolonged freeze-thaw cycles,but both freeze-thaw cycles and water content significantly influence cohesion.(4)Vertical surrounding rock pressure increases after the initial freeze-thaw cycle,particularly with higher water content,although freeze-thaw cycles have minimal effect on it.(5)Freeze-thaw cycles lead to a substantial increase in lateral surrounding rock pre

关键词： Moraines Freeze-thaw cycles Direct shear test Surrounding rock pressure

Oxygen and nitrogen-doped metal-free carbon catalysts for hydrochlorination of acetylene

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Chinese Journal of Chemical Engineering 2016年第4期24卷 484-490页

作者： Tongtong Zhang Jia Zhao jiangtao xu Jinhui xu Xiaoxia Di Xiaonian Li Industrial Catalysis Institute of Zhejiang University of Technology Hangzhou 310014 China

Activated carbon was tested as metal-free catalyst for hydrochlorination of acetylene in order to circumvent the problem of environment pollution caused by mercury and high cost by noble metals. Oxygen-doped and nitrogen-doped activated carbons were prepared and characterized by XPS, TPD and N2 physisorption methods. The influences of the surface functional groups on the catalytic performance were discussed base on these results. Among all the samples tested, a nitrogen-doped sample, AC-n-US00, exhibited the best performance, the acety- lene conversion being 92% and vinyl chloride selectivity above 99% at 240 ~C and C2H2 hourly space velocity 30 h- 1. Moreover, the AC-n-US00 catalyst exhibited a stable performance during a 200 h test with a conversion of acetylene higher than 76% at 210 ~C at a C2H2 hourly space velocity 50 h 1. In contrary, oxygen-doped catalyst had lower catalytic activities. A linear relationship between the amount of pyrrolic-N and quaternary-N species and the catalytic activity was observed, indicating that these nitrogen-doped species might be the active sites and the key in tuning the catalytic performance. It is also found that the introduction of nitrogen species into the sample could significantly increase the adsorption amount of acetylene. The deactivation of nitrogen- doped activated carbon might be caused by the decrease of the accessibility to or the total amount of active sites.

关键词： Acetylene hydrochlorinationActivated carbonSurface chemistryOxygenated groupNitrogen-doped

A variable threshold visual sensing and image reconstruction method based on pulse sequence

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Science China(Information Sciences) 2022年第2期65卷 257-258页

作者： jiangtao xu Peng LIN Zhiyuan GAO Kaiming NIE Liang xu School of Microelectronics Tianjin University Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology

Dear editor,Pulsed-based CMOS image sensor (CIS) outperforms classic CIS in terms of data rate,and is able to achieve ultra-highspeed imaging[1].A pulsed-based CIS which is able to capture the movement of the hard disk rotating at 6000 r/min,was designed in our previous work[2,3].The main problems of the pulse-based sensing mechanism are nonlinearity and readout *** light intensity is inversely proportional to the pulse interval[4],reconstructed images will involve loss of gray levels or lag in various light conditions[5].

关键词： pulse sequence variable threshold image reconstruction visual sensing adaptive video reconstruction

A dynamic photoresponse model for a pinned photodiode in CMOS image sensors

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Optoelectronics Letters 2022年第7期18卷 419-424页

作者： AO Jinghua GAO Zhiyuan GAO Jing xu jiangtao Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology School of MicroelectronicsTianjin UniversityTianjin UniversityTianjin 300072China

A novel dynamic photoresponse model for complementary metal-oxide-semiconductor(CMOS)image sensors with pinned photodiode(PPD)structures is *** PPD is regarded as the bonding structure of the two p-n *** transient current equation of the two junctions is calculated by the current-voltage formula of the p-n junction,and the photoresponse curve of the PPD is calculated and drawn by the numerical *** results show that the dynamic model successfully restores the entire process of the electron accumulation in the *** difference between the full well capacity(FWC)values which were calculated by the proposed model and the simulation results is less than 5%,which is much smaller than the error of 40%for the traditional model.

关键词： photoresponse pinned dynamic

Flexible and reusable cap-like thin Fe2O3 film for SERS applications

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Nano Research 2019年第2期12卷 381-388页

作者： jiangtao xu Xiaoting Li Yuxiang Wang Ronghui Guo Songmin Shang Shouxiang Jiang Institute of Textiles and Clothing The Hong Kong Polytechnic University Hong Kong 999077 Hong Kong China College of Light Industry Textile and Food Engineering Sichuan University Chengdu 610000 China

Cap-like α-Fe2O3 films are fabricated and deposited onto quartz fabric by using radio frequency magnetron sputtering and *** treated fabric sample in this study shows highly sensitive surface-enhanced Raman scattering (SERS) and excellent flexibility,reproducibility and *** addition,the sample can be recovered after a washing process with an organic solvent and repeatedly *** sensitive SERS performance is attributed to chemical enhancement through a charge transfer ***,the SERS performance is also found to be dependent on the light coupling *** the light absorbance rate of the α-Fe2O3 films increases at a wavelength near that of laser light,the film shows excellent sensitivity due to light coupling effect.

关键词： α-Fe2O3 quartz fabric flexible surface-enhanced Raman scattering (SERS) Raman sensor

A column-shared histogramming TDC with pixel-to-pixel coincidence detection and compact analog counters for Flash LiDAR sensor

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Science China(Information Sciences) 2024年第8期67卷 345-346页

作者： Haoran WU Kaiming NIE jiangtao xu Qinglong LIN Yingying JIAO School of Microelectronics Tianjin University Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology

In recent years, Flash LiDAR sensors based on direct timeof-flight(DToF) have been playing an increasingly important role in various 3D imaging fields. In order to perform a histogram on the chip to reduce the data rate, it is inevitable to use a large-size histogramming time-to-digital converter(hTDC) in a Flash LiDAR sensor. However, a large-size hTDC limits the spatial resolution of the sensor.

关键词： Pixels

A high dynamic range pixel using lateral overflow integration capacitor and adaptive feedback structure in CMOS image sensors

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Optoelectronics Letters 2023年第12期19卷 721-726页

作者： YANG Yuejin xu jiangtao MA Biao CHEN Quanmin NIE Kaiming School of Microelectronics Tianjin UniversityTianjin300072China Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology Tianjin UniversityTianjin300072China

This letter proposes a novel high dynamic range(HDR)pixel using lateral overflow integration capacitor(LOFIC)and adaptive feedback *** detailed analysis of the voltage feedback mechanism,the conversion gain(CG),full well capacity(FWC)and dynamic range(DR)performances of the feedback LOFIC pixel are analytically *** verification results reveal that the equivalent FWC of the feedback LOFIC pixel is 1.89 times of conventional LOFIC pixel,and the DR extension is 5.5 *** on 110 nm CMOS process,a 5.0µm pixel layout is presented,using 13.3 fF capacitance to achieve 83 ke-FWC and 102.8 dB DR,which are 44 ke-and 97.3 dB of conventional LOFIC pixel under the same design *** also demonstrates that the feedback LOFIC pixel can reduce the dependence of extended DR on capacitor area,and can be used as a reference for HDR pixels design.

关键词： HDR dynamic integration

Incomplete charge transfer in CMOS image sensor caused by Si/SiO_(2)interface states in the TG channel

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Journal of Semiconductors 2023年第11期44卷 101-108页

作者： Xi Lu Changju Liu Pinyuan Zhao Yu Zhang Bei Li Zhenzhen Zhang jiangtao xu School of Electronics and Information Hangzhou Dianzi UniversityHangzhou 310018China Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology School of MicroelectronicsTianjin UniversityTianjin 300072China Chongqing Optoelectronics Research Institute Chongqing 400060China

CMOS image sensors produced by the existing CMOS manufacturing process usually have difficulty achieving complete charge transfer owing to the introduction of potential barriers or Si/SiO_(2)interface state traps in the charge transfer path,which reduces the charge transfer efficiency and image *** now,scholars have only considered mechanisms that limit charge transfer from the perspectives of potential barriers and spill back effect under high illumination ***,the existing models have thus far ignored the charge transfer limitation due to Si/SiO_(2)interface state traps in the transfer gate channel,particularly under low ***,this paper proposes,for the first time,an analytical model for quantifying the incomplete charge transfer caused by Si/SiO_(2)interface state traps in the transfer gate channel under low *** model can predict the variation rules of the number of untransferred charges and charge transfer efficiency when the trap energy level follows Gaussian distribution,exponential distribution and measured *** model was verified with technology computer-aided design simulations,and the results showed that the simulation results exhibit the consistency with the proposed model.

关键词： CMOS image sensor charge transfer interface state traps

Modeling the photon counting and photoelectron counting characteristics of quanta image sensors

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Journal of Semiconductors 2021年第6期42卷 25-34页

作者： Bowen Liu jiangtao xu Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology School of MicroelectronicsTianjin UniversityTianjin 300072China

A signal chain model of single-bit and multi-bit quanta image sensors(QISs)is *** on the proposed model,the photoresponse characteristics and signal error rates of QISs are investigated,and the effects of bit depth,quantum efficiency,dark current,and read noise on them are *** the signal error rates towards photons and photoelectrons counting are lower than 0.01,the high accuracy photon and photoelectron counting exposure ranges are ***,an optimization method of integration time to ensure that the QIS works in these high accuracy exposure ranges is *** trade-offs between pixel area,the mean value of incident photons,and integration time under different illuminance level are *** the 3-bit QIS with 0.16 e-/s dark current and 0.21 *** noise,when the illuminance level and pixel area are 1 lux and 1.21μm^(2),or 10000 lux and 0.21μm^(2),the recommended integration time is 8.8 to 30 ms,or 10 to21.3μs,*** proposed method can guide the design and operation of single-bit and multi-bit QISs.

关键词： CMOS image sensor quanta image sensor photon counting photoelectron counting signal error rate integration time