高光谱成像用高帧频CMOS图像传感器北大核心

针对高帧频、全局曝光和光谱平坦等成像应用需求,设计了一款高光谱成像用CMOS图像传感器。其光敏元采用PN型光电二极管,读出电路采用5T像素结构。采用列读出电路以及高速多通道模拟信号并行读出的设计方案来获得低像素固定图像噪声(FPN)和非均匀性抑制。芯片采用ASMC 0.35μm三层金属两层多晶硅标准CMOS工艺流片,为了抑制光电二极管的光谱干涉效应,后续进行了光谱平坦化VAE特殊工艺,并对器件的光电性能进行了测试评估。电路测试结果符合理论设计预期,成像效果良好,像素具备积分可调和全局快门功能,最终实现的像素规模为512×256,像元尺寸为30μm×30μm,最大满阱电子为400 ke^(-),FPN小于0.2%,动态范围为72 dB,帧频为450 f/s,相邻10 nm波段范围内量子效率相差小于10%,可满足高光谱成像系统对CMOS成像器件的要求。     

Synthesis and characterizations of highly responsive H2S sensor using p-type Co3O4 nanoparticles/nanorods mixed nanostructures

High-quality p-type semiconducting Co₃O₄ with mixed morphology of nanoparticles/nanorods are synthesized using a hydrothermal route for high response and selective hydrogen sulphide (H₂S) sensor application. XRD and Raman studies revealed the crystal structure and molecular bonding for obtained Co₃O_4, respectively. The nanoparticles/nanorods-like structures were confirmed for Co₃O₄ using FESEM and TEM analysis. The EDS and XPS spectra analysis were carried out for elemental composition and chemical atomic states of Co₃O₄. The Co₃O₄ sensor is investigated for gas sensing properties in dynamic conditions. The sensor exhibited the highest selectivity towards H₂S among various hydrogen-contained gases at 225 °C. The sensor revealed a high response of 357% and 44% for 100 and 10 ppm H₂S gas concentrations, respectively. The Co₃O₄ sensor exhibited a systematic dynamic resistance response for 100–10 ppm range H₂S gas. The excellent dynamic resistance repeatability of the sensor was shown towards 25 ppm H₂S gas. The response of Co₃O₄ sensor was investigated at different operating temperatures and H₂S concentrations. The sensor stability and H₂S sensing mechanism for the Co₃O₄ sensor have been reported. Highly uniform and mixed nanostructures of Co₃O₄ can be the potential sensor material for real-time high-performance H₂S sensor application.     

建筑结构控制爆破拆除的力学分析与应用

应用运动学、动力学理论建立建(构)筑物控爆坍落过程的力学模型,进而研究在非定常约束条件下坍落结构的力学特征。首次提出了采用延时起爆技术时,非自由质点系及其广义坐标应是建立在每一段位上的瞬间虚位移。在此基础上,分析求解运动过程中时控单元的质点自由度,为精确选定爆破部位及时序提供了设计理论和计算依据。同时,结合振动理论,将控爆时差、结构载荷分布调制为振动系统,形成坍落结构梁板单元的强迫振动,充分实现在运动中进一步解体、破碎其自身结构,并形成具有明显缓冲效果的下落过程。应用实践结果证明力学分析是正确的,为工程结构爆破拆除计算机辅助设计及动态模拟技术的有效应用奠定了基础。     

基于FLAC3D的破碎围岩巷道支护效果分析

为了解破碎围岩分别采用锚杆支护、锚喷支护以及锚喷+锚索耦合三种支护方式下的支护效果,进而为破碎围岩巷道选择合理的支护方式提供参考。通过借助FLAC^3D软件建立数值模型,分析不同支护条件下的破碎围岩巷道位移量、应力分布以及塑性区的时空演化特征。结果表明,采用锚喷+锚索耦合支护时,可以较好的控制巷道围岩的位移量、减小应力集中效应、缩小塑性区的影响范围。     

Ammonia gas sensing and magnetic permeability of enhanced surface area and high porosity lanthanum substituted Co–Zn nano ferrites

This work reports magnetic permeability and ammonia gas sensing characteristics of La³⁺ substituted Co–Zn nano ferrites possessing chemical formula Co_0.7Zn_0.3La_xFe_2-2xO₄ (x = 0–0.1) synthesized by a sol-gel route. Refinement of X-ray diffraction (XRD) patterns of the ferrite powders by the Rietveld technique has revealed the creation of single-phase spinel structure. The tenancy of constituent cations at tetrahedral/octahedral sites was obtained from the refinement of XRD. The crystallite sizes calculated from the W–H method vary from 20 to 24 nm. The scanning electron microscope (SEM) profiles of the ferrite samples were analyzed for the morphological details. The energy dispersive X-ray analysis (EDAX) patterns of the samples were obtained to test the elemental purity of the ferrites within their stoichiometry. The transmission electron microscope (TEM) image of the ferrite (x = 0.1) exhibits the spherical and oval shaped particles with a mean size of 20 nm. Fourier transform infra-red (FTIR) spectra were analyzed to confirm the superseding of La³⁺ cations at octahedral sites. The Brunauer-Emmett-Teller (BET) analysis of nitrogen adsorption-desorption isotherms of the ferrites was performed to investigate the porous structure and to determine the surface area of the nanocrystalline ferrites. The oxidation states of the constituent ions were confirmed by means of X-ray photoelectron spectroscopy (XPS). The complex permeability as a function of frequency was studied to explore the effects of structural parameters on the magnetic behaviour of the ferrites. Analysis of gas sensing properties of the ferrites have proved that the Co–Zn–La ferrite with controlled La composition can be utilized as an effective ammonia gas sensing material in commercial gas sensors.     

缺水传感器改进设计

针对一种煤矿用本安型缺水传感器在现场安装及维护难度大,以及抽采泵供水状态下管道内有水但传感器检测显示为无水,或抽采泵停止工作时传感器检测显示有水问题,分析原产品中磁体及探头感应装置结构。改进其结构形式,并优化安装,使检测稳定可靠。实现抽采泵管道用缺水传感器的可靠性设计和轻量化设计。     

Flexible electronic skin with high performance pressure sensing based on PVDF/rGO/BaTiO3 composite thin film

The wearable intelligent electronic product similar to electronic skin has a great application prospect. However, flexible electronic with high performance pressure sensing functions are still facing great challenges. In this paper, the highly sensitive flexible electronic skin (FES) based on the PVDF/rGO/BaTiO₃ composite thin film was fabricated using the near-field electrohydrodynamic direct-writing (NFEDW) method. The PVDF/rGO/BaTiO₃ composite solution was directly written on flexible substrate by the NFEDW method to fabricate FES with micro/nano fiber structure, which has the function of sensing pressure with high sensitivity and fast response. The surface morphology and microstructure were characterized by SEM, AFM, and optical microscope in detail. The fabricated FES has high sensitivity (59 kPa⁻¹) and faster response time (130 ms). FES has been successfully applied to the detection of human motion and subtle physiological signals. The experimental results show that FES has good stability and reliability. FES can recognize human motion, and it has a broad application prospect in the field of wearable devices.     

基于K-means和SOM的水下传感器数据采集方法

随着海洋资源勘探和海洋污染物监控工作的开展，水文数据的监测和采集等已经成为重要的研究方向。其中，水下无线传感器网络在水文数据采集过程中起着举足轻重的作用。本文研究的是水下无线传感器二维监测网络模型中，传感器节点数据采集的问题，其设计方法是通过自组织映射（Self-organizing mapping，SOM）对传感器节点进行路径最优化处理，结合优化的路径图形和K-means算法找到路径内部聚合点，利用聚合点和传感器的节点得到传感器通信半径内的数据采集点，最后通过SOM得到水下机器人（Autonomous underwater vehicle，AUV）到各个数据采集点采集数据的最优路径。经过实验验证，在水下1 200 m×1 750 m范围内布置52个传感器节点的情景下，数据采集点相比于传感器节点路径规划采用相同的采集顺序得到的路径优化了6.7%；对数据采集点重新进行自组织路径规划得到的路径比传感器结点路径的最优解提高了12.2%。增加传感器节点的数量，其结果也大致相同，因此采用该方法可以提高水下机器人采集数据的效率。     

Influence of substrate temperature on the microstructure of YSZ films and their application as the insulating layer of thin film sensors for harsh temperature environments

Thin film sensors are employed to monitor the health of hot-section components of aeroengine intelligence (for instance, blades), and electrical insulating layers are needed between the metal components and thin film sensors. For this purpose, the electrical insulation characteristics of an yttria-stabilized zirconia (YSZ)/Al₂O₃ multilayer insulating structure were investigated. First, YSZ thin films were deposited by DC reactive sputtering at various substrate temperatures, and the microstructural features were investigated by scanning electron microscopy and X-ray diffraction. The results indicate that the micromorphology of the YSZ thin film gradually became denser with increasing substrate temperature, and no new phases appeared. The compact and uniform topography of the YSZ thin film improved the insulation properties of the multilayer insulating structure and enhanced the adhesion of the thin film sensors. In addition, the electrical insulation properties of the YSZ/Al₂O₃ multilayer insulating structure were evaluated via insulation resistance tests from 25 to 800 °C, in which the YSZ thin film was deposited at 550 °C. The results show that the insulation resistance of the multilayer structure increased by an order of magnitude compared with that of the conventional Al₂O₃ insulating layer, reaching 135 kΩ (5.1 × 10^?6 S/m) at 800 °C. Notably, the insulation resistance was still greater than 75 kΩ after annealing at 800 °C for 5 h. Finally, the shunt effect of the YSZ/Al₂O₃ multilayer insulating structure was estimated using a PdCr thin film strain gauge. The relative resistance error was 0.24%, which demonstrates that the YSZ/Al₂O₃ multilayer insulating structure is suitable for thin film sensors.     

High-temperature electrical properties of polymer-derived ceramic SiBCN thin films fabricated by direct writing

The in situ temperature monitoring of hot components in harsh environments remains a challenging task. In this study, SiBCN thin-film resistance grids with thicknesses of 1.8 μm were fabricated on alumina substrates via direct writing. Owing to their dense microscopic morphology and extremely high graphitisation level, the produced SiBCN films exhibited large high-temperature oxidation resistance and electrical conductivity. The resistance–temperature, stability, and repeatability characteristics of these films were examined in an aerobic environment at temperatures up to 800 °C. The obtained results revealed that the thermistor resistance decreased monotonously with increasing temperature from room temperature to 800 °C. The SiBCN film resistance variations observed during repeated temperature cycling in the regions of 505–620 °C and 610–720 °C were 0.09% and 1.7%, respectively. The high cyclability and stability of the SiBCN thin film thermistor suggested its potential applicability for the in situ temperature monitoring of hot components in harsh environments.