Single-wall carbon nanotubes (SWCNTs) have unique electrical properties, making them potential silicon and copper replacements in semiconductors and nanointerconnects. Current research focuses on single vacancy defects, needing expansion to other topological defects. In this study, we account for the presence of topological defects and develop a model that demonstrates their impact on the electrical properties of carbon nanotubes (CNTs) by using a degradation coefficient for the conductivity. This study employs density functional theory combined with the nonequilibrium Green's function method to systematically analyze the influence of various topological defects on the electronic structure and transport characteristics of SWCNTs, using I-V curves, transmission spectra, and 3D transmission spectra. The results indicate that defects of the same type substantially degrade the electronic transport properties of CNTs, with the degree of degradation varying based on the defects' positions and quantities. This degradation can result in a reduction of over 20% in the electronic transport capacity compared with ideal CNTs. A linear positive correlation exists between the extent of degradation and the magnitude of the defects. Furthermore, the presence of a small number of 5-8-5 defects and Stone-Wales defects can induce bandgap opening from 0.109 to 0.549 eV for the bandgap of (6,6) CNTs. However, a high defect concentration reduces the bandgap, potentially to zero. Notably, regardless of whether the bandgap increases or decreases, the bandgap of (6,6) CNTs remains smaller than the bandgap of (11,0) semiconductor CNTs, leading to the transition of SWCNTs to metallic conductors. Finally, the differential conductivity diagram of CNTs with topological defects was analyzed, demonstrating that introducing specific 5-8-5 defects can effectively regulate the electrical properties of the CNTs. This paper analyzes the effects of defects on the CNTs electrical properties and finds a regulatory effect, providing a reference for carbon-based transistor manufacturing.

Carbonnanotubes (CNTs) have excellent electrical properties. However,it is challenging to demonstrate these properties in actual electrochemicalmeasurements fully. Previous research has improved the electricalproperties of CNTs through welding experiments. But the mechanismof the conductivity enhancement is still unclear. The welding processlacks adequate mechanistic studies and theoretical models. This articlepresents a theoretical model of a CNT circuit with staggered electrodes,which considers the effect of twist angle on a CNT bundle. A weldingmodel of the CNT bundle circuit is also developed based on the structuralchanges of CNTs after welding and characterized by the resistanceratio of the CNT circuit pre- and post-welding. The welding modelis analyzed to explore how the quantity, diameter, and length of CNTsin the bundle affect the welding effect. An electrical measurementsystem for CNTs was established to validate the welding model usinga nanomanipulation system compatible with a scanning electron microscope.Then, a constant voltage and long-duration electric welding experimentwas performed, which showed that the conductivity was enhanced about1.5-4 times after welding. The results also demonstrated thatlonger and fewer CNTs in the bundle could improve the electrical conductivityby the welding process more significantly. These findings were consistentwith the trend of the welding model. This article establishes a weldingtheoretical model of the CNT bundle with staggered electrodes, whicheffectively accounts for the electrical conductivity enhancement duringCNT welding and will help more fully express excellent performancein carbon-based nanoelectronic devices, nanoelectromechanical systems,and electrocatalysts in its manufacturing stage.

Microrobots for targeted drug delivery in blood vessels have attracted increasing interest from researchers. In this work, hydrogel-based capsule microrobots are used to wrap drugs and deliver drugs in blood vessels. In order to prepare capsule microrobots of different sizes, a triaxial microfluidic chip is designed and built, and the formation mechanism of three flow phases including the plug flow phase, bullet flow phase and droplet phase during the preparation of capsule microrobots is studied. The analysis and simulation results show that the size of the capsule microrobots can be controlled by the flow rate ratio of two phases in the microfluidic chip, and when the flow rate of the outer phase is 20 times that of the inner phase in the microfluidic chip, irregular multicore capsule microrobots can be prepared. On this basis, a three degree of freedom magnetic drive system is developed to drive the capsule microrobots to reach the destination along the predetermined trajectory in the low Reynolds number environment, and the magnetic field performance of the magnetic drive system is simulated and analyzed. Finally, in order to verify the feasibility of targeted drug delivery of the capsule microrobots in the blood vessel, the motion process of the capsule microrobots in the vascular microchannel is simulated, and the relationship between the motion performance of the capsule microrobots and the magnetic field is studied. The experimental results show that the capsule microrobots can reach a speed of 800 μm s-1 at a low frequency of 0.4 Hz. At the same time, the capsule microrobots can reach a peak speed of 3077 μm s-1 and can continuously climb over a 1000 μm high obstacle under a rotating magnetic field of 2.4 Hz and 14.4 mT. Experiments show that the capsule microrobots have excellent drug delivery potential in similar vascular curved channels driven by this system.

The electron transport properties of Y-type zigzag branched carbon nanotubes (CNTs) are of great significance for micro and nano carbon-based electronic devices and their interconnection. Based on the semi-empirical method combining tight-binding density functional theory and non-equilibrium Green's function, the electron transport properties between the branches of Y-type zigzag branched CNT are studied. The results show that the drain-source current of semiconducting Y-type zigzag branched CNT (8, 0)-(4, 0)-(4, 0) is cut-off and not affected by the gate voltage in a bias voltage range [-0.5 V, 0.5 V]. The current presents a nonlinear change in a bias voltage range [-1.5 V,-0.5 V] and [0.5 V, 1.5 V]. The tangent slope of the current-voltage curve can be changed by the gate voltage to realize the regulation of the current. The regulation effect under negative bias voltage is more significant. For the larger diameter semiconducting Y-type zigzag branched CNT (10, 0)-(5, 0)-(5, 0), only the value of drain-source current increases due to the larger diameter. For metallic Y-type zigzag branched CNT (12, 0)(6, 0)-(6, 0), the drain-source current presents a linear change in a bias voltage range [-1.5 V, 1.5 V] and is symmetrical about (0, 0). The slope of current-voltage line can be changed by the gate voltage to realize the regulation of the current. For three kinds of Y-type zigzag branched CNT with different diameters and different conductivity, the current-voltage curve trend changes from decline to rise when the branch of drain-source is exchanged. The current regulation effect of semiconducting Y-type zigzag branched CNT under negative bias voltage is also more significant.

ZnO nanomaterials have been widely used in micro/nano devices and structure due to special mechanical/electrical properties, and its characterization is still deficient and challenging. In this paper, ZnO nanomaterials, including nanorod and nanowire are characterized by atomic force microscope (AFM) and nanomanipulator embedded in scanning electron microscope (SEM) respectively, which can manipulate and observe simultaneously, and is efficient and cost effective. Surface morphology and mechanical properties were observed by AFM. Results showed that the average Young's modulus of ZnO nanorods is 1.40 MPa and the average spring rate is 0.08 N/m. Electrical properties were characterized with nanomanipulator, which showed that the ZnO nanomaterial have cut-off characteristics and good schottky contact with the tungsten probes. A two-probe strategy was proposed for piezoelectric property measurement, which is easy to operate and adaptable to multiple nanomaterials. Experiments showed maximum voltage of a single ZnO nanowire is around 0.74 mV. Experiment criteria for ZnO manipulation and characterization were also studied, such as acceleration voltage, operation duration, sample preparation. Our work provides useful references for nanomaterial characterization and also theoretical basis for nanomaterials application.

基于汽车侧安全气帘缝纫市场的迫切需求,在现有花饰缝纫机的基础上设计了大行程的步进缝纫系统.该系统主要包括步进装置和辅助装置两部分,其中步进装置由移动装置、定位装置和夹紧装置3部分组成,辅助装置主要包括缝纫模板以及前、后延伸台.通过移动装置、定位装置以及夹紧装置的协调运动,在保证0.1 mm缝纫精度的前提下,将花饰缝纫机的可缝纫长度由之前的400 mm扩大至2000 mm,实现了对侧安全气帘等材料的大行程缝纫.通过有限元仿真分析,对夹紧装置的夹紧结构进一步优化,有效改善了夹紧装置的受力情况,满足了使用要求.

针对Tiny YOLOV3目标检测算法在实时检测中对行人等小目标漏检率高的问题,对该算法的特征提取网络、预测网络、损失函数等进行研究改进.首先,在特征提取网络中增加2步长的卷积层,代替原网络中的最大池化层进行下采样;接着,使用深度可分离卷积构造反残差块替换传统卷积,降低模型尺寸和参数量,增加高维特征提取;然后,在原网络两尺度预测的基础上增加一尺度,形成三尺度预测;最后,对损失函数中的边界框位置误差项进行优化.实验结果表明,改进后的Tiny YOLOV3算法的目标检测准确率比原算法提高了9.8％,满足实时性要求,具有一定鲁棒性.本文方法能够更好地提取目标特征,多尺度预测和边界框位置误差的改进能更准确地对目标进行检测.

In this study, we develop a ring laser gyroscope beam precision coupling assembly system to solve the problems of low assembly efficiency and poor quality consistency associated with manual beam precision coupling. Further, we analyze the principle of beam precision coupling with respect to ring laser gyroscope. Thus, the light field intensity of coupling beam is observed to follow a Gaussian distribution. Accordingly, we propose the photodetector pose adjustment method. Subsequently, the optical path change observed during the rotation of the optical prism is analyzed and a method is proposed to adjust the position of the combined prism. Additionally, an adjustment strategy is formulated with respect to the position of the photodetector and the attitude of the combined prism. Then, a beam coupling assembly experiment is conducted on the ring laser gyroscope beam precision coupling system according to the aforementioned adjustment methods and strategies. The experimental results demonstrate that the proposed experimental assembly platform can complete the beam precision coupling assembly task.

Target detection is the basic technology of self-driving system. In this paper, the problem of high detection rate of pedestrians and other small targets is studied in real-time detection of Tiny YOLOV3 target detection algorithm, and the network structure of Tiny YOLOV3 algorithm is improved. 2-step convolutional layers are added to the network, and deep separable convolution constructs are used to replace the traditional convolutions. On the basis of the original two-scales prediction target of the network, a scale is added to form a three-scales prediction, which can makes the detection of small targets such as pedestrians more accurate. The experimental results show that the average accuracy of the improved target detection algorithm is 8.6% higher than that of Tiny YOLOV3, and it meets the real-time requirements and has certain robustness.

为了对30～60 m范围内输电线路上的绝缘子进行型号识别,建立了基于特征尺寸测量的绝缘子型号在线识别系统.通过椭圆拟合、尺寸测量和相似度匹配等关键算法实现对绝缘子型号的识别.首先通过系统的图像采集模块获取绝缘子的图像,并对图像中绝缘子的伞裙进行椭圆拟合,得到绝缘子各圈伞裙的半径在图像中的尺寸.然后通过免棱镜全站仪测量绝缘子的距离和俯仰角度,并对距离进行修正,根据测量模型计算绝缘子各圈伞裙的实际半径尺寸.最后根据绝缘子实测特征尺寸与标准特征尺寸间的欧氏距离进行相似度匹配,得到绝缘子的型号.实验结果验证了所提方法的有效性.

为了将荧光分子成像技术应用于临床进行手术导航、肿瘤边界识别、在体显微病理诊断等,设计了一种双模切换显微内窥镜成像系统,采用荧光素钠作为荧光分子探针,高亮度蓝光LED光源作为荧光激发光源,通过切换内窥成像探头,实现了两个模态下的成像:宽场白光内窥成像模式下进行手术导航,荧光分子成像进行病变肿瘤边界识别;显微内窥成像模式下,进行在体显微病理分析,确定肿瘤良恶性及其种类。本文研究了双模切换显微内窥镜成像系统的光学特性,搭建系统并测试了相关的性能指标,展示了该系统在小鼠肝脏多模式内窥成像下的效果。研究结果表明:宽场内窥成像可以实现组织颜色和边界特征识别,显微内镜成像系统可以实现分辨率达4.4μm的组织显微成像,能够满足在体肿瘤实时手术导航和显微病理诊断的临床需求。

The invention relates to an automatic assembling device for flexible shaft holes applied to large precision equipment. The automatic assembling device comprises a platform, a sleeve positioning and clamping device, a shaft supporting and positioning device, a flexible feeding moving device, two shaft hole assembling detection device and an auxiliary device. Positions of all the devices are adjusted through mechanisms such as hydraulic cylinders, sliding blocks and ball screws, the real-time positions of the devices are monitored through multiple laser sensors, and assembling of multiple types of the shaft holes of the precision equipment can be met. The flexibility of the assembling process is achieved through multiple elastic elements and force sensors, and the assembly force is monitored in real time. All the devices are installed on the same platform, the layout is ordered, the reliability is good, the operability is high, the detection precision is high, and the assembling quality and efficiency for assembling of the shaft holes for the large precision equipment are effectively improved.

In fringe projection profilometry, the nonlinear intensity response caused by the γ effect of a digital projector results in periodic phase error and therefore measurement error. Previous error correction methods are largely based on the calibration of single γ value. However, in practice, it is difficult to accurately model the full range of the intensity response with a one-parameter γ function. In this paper, a compensated intensity response curve is generated and fitted with the constrained cubic spline. With the compensated curve, the full range of the nonlinear intensity response can be corrected and the periodic phase errors can be removed significantly. Experimental results on a flat board confirm the average root mean square (RMS) of the phase error which can be reduced to at least 0.0049 rad.

调腔是激光陀螺制造过程中的关键环节.为实现复杂的激光陀螺调腔任务,在分析调腔原理的基础上,提出一种倾斜接触式的调腔方法,依靠球面镜自身重力使其贴合在谐振腔的光胶面上,保证了调腔的高平行度要求.由此开发一套倾斜接触式的由光学模块、调腔机构及控制模块、视觉检测模块及损耗测量模块组成的自动调腔系统.利用视觉检测模块及损耗测量模块获得的谐振腔输出光信息实现球面镜位置的闭环控制.通过分析损耗与光束光阑位置偏差之间的关系,设计粗、精结合的球面镜最佳位置自动搜索算法.调腔试验结果验证了倾斜接触式调腔方法的有效性.

Cavity adjustment is a critical step for manufacturing laser gyro. Location relation of the laser facula and the aperture images should be detected to provide control information for the movement of the cavity adjustment mechanism. According to the image features, a sequence image variance method is proposed to segment the laser facula image, and maximum variance between clusters method (Ostu algorithm) is adopted to acquire automatic threshold value to segment the aperture image. Use the edge detection of binary image to obtain pixel edge of the laser facula and the aperture images. And sub-pixel edge point information of the images is given by a parameter fitting method. Centre points coordinates of the laser facula and the aperture are achieved by fitting sub-pixel edge utilizing the least square ellipse fitting method. The experimental results of cavity adjustment verify the validity of image recognition method of the laser facula and the aperture.

考虑激光陀螺调腔人工检测耗时较长、易受干扰,本文建立了激光陀螺自动调腔系统.在分析激光陀螺调腔工艺的基础上,构建了一种由CCD相机和光电倍增管组成的多传感器信息融合体系结构,提出了基于D-S证据理论的激光陀螺调腔检测方法.通过分析计算CCD相机和光电倍增管检测到的信号得出光斑、光阑中心点坐标差值及陀螺损耗值,并由这些信息获得调腔质量的评价函数.然后,根据D-S证据理论对评价函数进行融合处理,分别获得陀螺调腔质量合格与不合格的信度函数,应用最大支持度规则对调腔质量进行综合判断.实验结果显示,基于DS证据理论的激光陀螺调腔方法检测准确率为91.14％,有效提高了调腔质量,验证了该方法的可行性.

解析梯度折射率(GRIN)光纤探针的光学特征参数,用于光学相干层析技术(OCT)探头超小型化的研究.在概述由单模光纤、无芯光纤和GRIN光纤镜头构成的GRIN光纤探针模型的基础上,定义GRIN光纤探针的工作距离和聚焦光斑尺寸等光学特征参数,并用高斯光束复参数矩阵变换的方法推导探针光学特征参数的数学表达式,提出了探针光学特征参数的验证方法.结果显示,当无芯光纤和GRIN光纤镜头长度分别为0.48 mm和0.17 mm时,理论计算的工作距离和聚焦光斑尺寸分别为1.05 mm和28.2 μm;实验测得的工作距离和聚焦光斑尺寸分别为1.0 mm和28 μm.理论计算与实测结果吻合,验证了GRIN光纤探针光学特征参数及其解析方法的有效性.

为解决激光陀螺人工调腔质量低、效率不高等缺点,提出一种由CCD相机和光电倍增管构成的多传感器信息融合调腔检测方法,该方法同时检测光斑、光阑中心点及陀螺损耗值,并将这些信息送入融合中心,经过融合计算得到陀螺调腔是否合格的综合判断。融合系统采用动量BP神经网络对多源信息进行融合,根据调腔过程中的输入、输出情况,设计包含输入层、隐含层及输出层的3层网络拓扑结构。实验结果表明,此种方法对激光陀螺调腔质量是否合格判断准确率为93.81%,比人工采用单一传感器分步检测准确率提高了6%。

A piezoelectric nanostage using bridge-type flexure hinge mechanisms is developed. Elastic beam theory was used to analyze the ideal and theoretic displacement amplification ratio and find that their value is mainly influenced by the length of the tilt rod and tilt angle of bridge-type. A multilayer S-type hinge is designed as the prismatic of moving platform. Stiffness and natural frequency model of the whole stage is built and find out that their value is mainly relevant to hinge thickness, tilt angle of bridge-type hinge and length of S-type hinge. Finally, finite element method (FEM) is used to verify the drived model. The errors of the total stiffness and the natural frequency of the stage between FEM and theory analysis are 3.8% and 6.6% respectively, which confirm the predictions of theory analysis.

针对光学精密装配工艺特点,提出一种基于LVDT的三维相对位姿检测方法。采用4个对称分布的LVDT检测光学装配过程中球面镜与谐振腔体的位姿关系,根据LVDT的读数推导得出球面镜与谐振腔体的相对位姿。设计采用集成信号调理芯片AD598的LVDT处理电路作为位姿检测的控制系统,通过实验得出LVDT微位移检测的分辨率为0.1μm,重复检测精度为±0.3μm,并能较好地跟踪方波及正弦波信号。采用PID算法实现球面镜的快速位姿定位。实验结果表明:当球面镜的加工及安装误差在允许范围内时,位姿检测系统可以在25 s内完成球面镜相对于谐振腔体的位姿调整,最大距离误差为0.5μm,最大角度误差为8″,充分验证了基于LVDT相对位姿检测方法的可行性。