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

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

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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

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Clustering-based temporal deep neural network denoising method for event-based sensors

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Optoelectronics Letters 2024年

作者： LI Jianing xu jiangtao GAO Jiandong Tianjin Key Laboratory of Imaging and Sensing， Microelectronics Technology， School of Microelectronics， Tianjin University

To enhance the denoising performance of event-based sensors， we introduce a clustering-based temporal deep neural network denoising method (CBTDNN). Firstly， to cluster the sensor output data and obtain the respective cluster centers， a combination of density-based spatial clustering of applications with noise (DBSCAN) and Kmeans++ is utilized. Subsequently， long short-term memory (LSTM) is employed to fit and yield optimized cluster centers with temporal information. Lastly， based on the new cluster centers and denoising ratio， a radius threshold is set， and noise points beyond this threshold are removed. The comprehensive denoising metrics F1＿score of CBTDNN have achieved 0.8931， 0.7735， and 0.9215 on the Traffic Sequences Dataset， Pedestrian Detection Dataset， and Turntable Dataset， respectively. And these metrics demonstrate improvements of 49.90%， 33.07%， 19.31%， and 22.97% compared to four contrastive algorithms， namely nearest neighbor (NNb)， nearest neighbor with polarity (NNp)， Autoencoder， and multilayer perceptron denoising filter (MLPF). These results demonstrate that the proposed method enhances the denoising performance of event-based sensors.

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Mutual-structure weighted guided image filtering for depth map restoration

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Optoelectronics Letters 2024年

作者： LIU Zijian SONG Jian CHEN Quanmin xu jiangtao Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology， School of Microelectronics， Tianjin University Spikesee Technology Co.， Ltd.

Although guided image filtering (GIF) is known for preserving edges and fast computation， it may produce inaccurate outputs in depth map restoration. In this paper， a novel confidence-weighted GIF called mutual-structure weighted GIF (MSWGIF) is proposed， which replaces the mean filtering strategy in GIF during handling overlapping windows. The confidence value is composed of a depth term and a mutual-structure term， where the depth term is utilized to protect the edges of the output， and the mutual-structure term helps to select accurate windows during the structure characteristics of the guidance image are transferred to the output. Experimental results show that MSWGIF reduces the root mean square error by an average of 12.37%， and the average growth rate of correlation is 0.07% on average. Additionally， the average growth rate of structure similarity index measure is 0.34%.

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全站仪一测回水平方向标准偏差的不确定度评定

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测绘与空间地理信息 2024年第4期47卷 183-185页

作者：许江涛陕西测绘仪器计量监督检定中心陕西西安710054

根据《全站型电子速测仪检定规程》的要求,“一测回水平方向标准偏差”是全站仪的必检项目,也是判定全站仪检定是否合格的重要指标。本文结合笔者所在单位实际,使用多目标平行光管法检定全站仪一测回水平方向标准偏差,分析影响测得值的... 详细信息

根据《全站型电子速测仪检定规程》的要求,“一测回水平方向标准偏差”是全站仪的必检项目,也是判定全站仪检定是否合格的重要指标。本文结合笔者所在单位实际,使用多目标平行光管法检定全站仪一测回水平方向标准偏差,分析影响测得值的不确定度来源,评定出Ⅰ级、Ⅱ级、Ⅲ级3个精度等级全站仪的一测回水平方向标准偏差的不确定度。

关键词：全站仪一测回水平方向标准偏差测量不确定度

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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

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木基电磁屏蔽/吸波材料研究进展

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林业工程学报 2024年第2期9卷 14-22页

作者：林秀仪戴振华韦喻译徐江涛胡传双华南农业大学材料与能源学院生物质材料与能源教育部重点实验室广州510642 岭南现代农业科学与技术广东省实验室茂名分中心茂名525032

生命健康、精密仪器和国防信息等领域对电磁屏蔽/吸波材料均有迫切的需求,但传统金属基电磁屏蔽/吸波材料存在屏蔽效能质量比低、易造成二次环境污染和屏蔽机理单一等不足,而新型碳基纳米电磁屏蔽/吸波材料制备烦琐、价格昂贵。木材及... 详细信息

生命健康、精密仪器和国防信息等领域对电磁屏蔽/吸波材料均有迫切的需求,但传统金属基电磁屏蔽/吸波材料存在屏蔽效能质量比低、易造成二次环境污染和屏蔽机理单一等不足,而新型碳基纳米电磁屏蔽/吸波材料制备烦琐、价格昂贵。木材及其衍生品具有多级孔结构、强重比高、绿色低碳、易加工、可再生等天然优势,开发轻质、环境友好的木基电磁屏蔽/吸波材料逐渐成为研究热点。系统分析和讨论了国内外木基电磁屏蔽/吸波材料的研究进展,介绍了电磁屏蔽材料的基本概念和原理,对比了涂层型、填充型、碳化型3种制备方法的特点及适用范围,总结了制备工艺、孔隙结构、导电/磁性填充组分等因素对电磁屏蔽和吸波性能的影响,并分析了木基电磁屏蔽/吸波材料中的电磁屏蔽机理和吸波机制,以及木质材料的各向异性结构对屏蔽性能的调控机制,最后对木基电磁屏蔽/吸波材料的未来发展趋势和研究重点进行了展望,可为木基电磁屏蔽/吸波材料的研发提供一定参考。

关键词：木材电磁屏蔽电磁波吸收木基屏蔽材料木基吸波材料

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采用两步式数字校准的低温漂松弛振荡器

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西安交通大学学报 2024年第8期58卷 166-174页

作者：裴磊韩佳利张程跃齐欢欢张杰许江涛王晓飞张鸿西安交通大学微电子学院西安710049

针对传统片上振荡器设计面临的时钟频率难以实现高精度校准的问题,提出基于二分搜索法的数字校准方法,实现了振荡频率校准并提高了校准的线性度。校准算法采用了粗校准加细校准的两步式校准过程,大大增加了频率校准范围。针对振荡频率... 详细信息

针对传统片上振荡器设计面临的时钟频率难以实现高精度校准的问题,提出基于二分搜索法的数字校准方法,实现了振荡频率校准并提高了校准的线性度。校准算法采用了粗校准加细校准的两步式校准过程,大大增加了频率校准范围。针对振荡频率的温度漂移问题,提出了新的温度补偿方案,在传统一阶温度补偿的基础上,增加了亚阈值电流自补偿的高阶补偿机制,大大降低了温度变化对输出频率的影响。在校准电路的设计中,合理设置开关电阻阵列的温度系数以保证输出频率的校准不影响输出频率的温度稳定性。对振荡器版图提取了寄生参数,并进行了仿真,仿真结果表明:经过所提频率校准和温度补偿方案,典型情况下振荡频率误差小于0.04%;在-40~125℃温度范围内频率误差小于±0.12%;2.5~5.5 V电源电压范围内频率随电源电压变化误差小于±0.13%;电路工作电流为47.6μA,完成一次校准时长不超过2.7 ms。该振荡器可用于物联网、处理器等应用,可以取代片外晶体振荡器,能够降低系统成本和体积。

关键词：松弛振荡器高精度两步式数字校准高阶温度补偿

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Motion detection for high-speed high-brightness objects based on a pulse array image sensor

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Frontiers of Information Technology & Electronic Engineering 2022年第1期23卷 113-122页

作者： Peiwen ZHANG jiangtao xu Huafeng NIE Zhiyuan GAO Kaiming NIE School of Microelectronics Tianjin UniversityTianjin300072China Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology Tianjin300072China

We describe a method of optical flow extraction for high-speed high-brightness targets based on a pulse array image sensor(PAIS).PAIS is a retina-like image sensor with pixels triggered by light;it can convert light into a series of pulse *** method can obtain optical flow from pulse data directly by accumulating continuous *** triggered points can be used to filter redundant data when the target is brighter than the *** method takes full advantage of the rapid response of PAIS to high-brightness *** applied this method to extract the optical flow of high-speed turntables with different background brightness,with the sensor model and actual data,*** the sampling condition of 2×10^(4) frames/s,the optical flow could be extracted from a high-speed turntable rotating at 1000 r/*** than 90%of redundant points could be filtered by our *** results showed that the optical flow extraction algorithm based on pulse data can extract the optical flow information of high-brightness objects efficiently without the need to reconstruct images.

关键词： Optical flow Retina-like image sensor Pulse triggered High-speed targets Vision processing

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Design of CMOS active pixels based on finger-shaped PPD

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Journal of Semiconductors 2020年第10期41卷 38-44页

作者： Feng Li Ruishuo Wang Liqiang Han jiangtao xu Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology School of MicroelectronicsTianjin UniversityTianjin 300072China Electronic Instrumentation Laboratory Delft University of TechnologyDelft 2628CDNetherlands

To improve the full-well capacity and linear dynamic range of CMOS image sensor,a special finger-shaped pinned photodiode(PPD)is *** terms of process,the first N-type ion implantation of the PPD N buried layer is extended under the transfer gate,thereby increasing the PPD *** on TCAD simulation,the width and spacing of PPD were precisely adjusted.A high full-well capacity pixel design with a pixel size of 6×6μm^2 is realized based on the 0.18μm CMOS *** simulation results indicate that the pixel with the above structure and process has a depletion depth of 2.8μm and a charge transfer efficiency of 100%.The measurement results of the test chip show that the full-well capacity can reach 68650 e–.Compared with the conventional structure,the proposed PPD structure can effectively improve the full well capacity of the pixel.

关键词： CMOS active pixel full well capacity full depletion

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