图像分割技术用于印刷电路板检测的研究

图像分割在图像分析、图像识别、图像检测等方面占有非常重要的地位,是从图像处理到图像分析的重要步骤,图像分割的好坏直接影响到图像分析的结果。针对此就印刷电路板检测过程中的图像分割进行研究。阈值分割技术的运算效率高、计算简单等特点非常适应印刷电路板检测的快速性和稳定性要求,因此着重介绍了四种阈值分割技术,并借用软件将各算法分别应用于实际的印刷电路板图像,然后对各个阈值化算法的分割结果做了对比和简要分析。     

基于Arduino Uno R3的蓝牙操控机械臂设计

为行动不便的人群提供各种服务的机器人正在成为一种迫切的社会需求.基于以上思路,可设想出具有抓取性能的电子设备可实现此功能,故构想出机械臂.为提升该系统的性能通过对软件及硬件架构进行深层次分析,提出了一种控制系统架构的设计方法如下--该机械臂以Arduino Uno R3为控制核心,利用蓝牙进行操控,舵机使之运动.如此可...     

燃烧合成前驱物制备超细AlN-SiC复合粉末

以硅溶胶(SiO2·nH2O)、葡萄糖(C6H12O6·H2O)、硝酸铝(Al(NO3)3)和尿素(CO(NH2)2)为原料,采用低温燃烧合成方法,制备出粒度细小、混合均匀的(Al2O3+SiO2+C)前驱物,然后将前驱物采用两步碳热还原反应制备AlN-SiC复合粉末.研究结果表明:(Al2O3+SiO2+C)前驱物具有较高的反应活性,还原反应速率快,前驱物首先在1600℃通氩气保温3h然后再于1600℃通氮气保温3h可实现完全转化,制备的AlN-SiC复合粉末主要由尺寸为80～100 nm的球形颗粒组成.     

“互联网+”背景下的高校图书馆服务创新与转型发展研究

文章主要依据我国高校图书馆服务的发展情况,分析了互联网+环境下,高校图书馆服务创新与转型的重要意义,提出了目前高校图书馆服务中所存在的问题,并针对这些问题给出了一系列有针对性的方案。     

多喷管液体火箭动力系统尾焰辐射特性研究

为研究多喷管液体火箭动力系统尾焰辐射特性,以液氢/液氧和液氧/煤油发动机组成的多喷管动力系统为模型,采用CFD技术对尾焰流场进行计算,利用气体辐射传输方程和大气透过率计算模型对尾焰辐射特性进行计算,结果表明:复燃反应主要发生在尾焰的边界与空气掺混区域,导致尾焰的辐射特性增强;随着飞行高度及观测角的增加,尾焰辐射特性逐渐增强;可视化计算可以有效捕捉到尾焰流场的结构。     

基于Wi-Fi即时定位与映射像素模板匹配的室内运动地图构建与定位

传统指纹定位方法由于建库人力时间开销大、系统通用性不强约束着指纹定位系统的推广,为了解决该问题同时结合即时定位与映射(SLAM)技术的优势,该文提出一种新的Wi-Fi/微机电系统(MEMS)融合室内运动地图构建与定位方法。首先利用行人航迹推算(PDR)、最小描述长度(MDL)原则和基于密度的空间聚类算法(DBSCAN)对众包运动轨迹进行预处理,提出基于轨迹主路径的运动地图构建方法。之后提出基于像素模板的地图匹配方法获取地图的绝对位置,并采用抗差扩展卡尔曼滤波(EKF)对目标位置进行最优估计。实验结果表明,所提聚类方法可以准确构建各区域运动地图,在少量的人力时间开销下实现较高的定位精度。     

Bone Plate Composed of a Ternary Nanohydroxyapatite/Polyamide 66/Glass Fiber Composite: Biocompatibility In Vivo and Internal Fixation for Canine Femur Fractures

Bone plates have been applied to fix fractures for over a hundred years. Metal plates are the gold standard. However, an increasing number of clinical practices and animal experiments have shown that metal plates have had incidents of failure due to their rigid fixation and long‐term complications. Degradable composites present the advantages of a lower elastic modulus and absorbable properties but are unsuitable for load‐bearing applications. Nondegradable bone plates composed of a nanohydroxyapatite/polyamide 66/glass fiber (n‐HA/PA66/GF) composite are prepared, which have enough strength and a low elastic modulus for an internal fixation device. To better assess its function as a bone plate, animal experiments are conducted using a canine load‐bearing femur fracture model. The results show that the n‐HA/PA66/GF plate can fix fractures effectively. Gross observation, radiographic films, and histological analysis all show that the n‐HA/PA66/GF plate leads to a secondary (indirect) union with obvious callus formation, whereas the titanium plate leads to primary (direct) union due to rigid fixation. Furthermore, the histological results reveal that new bone grows at the interface and that the n‐HA/PA66/GF plate can integrate with native bone tissue. Consequently, the n‐HA/PA66/GF composite shows good potential as a bone plate to fix loading‐bearing bone fractures.     

光电导及光反射法测量AlGaN薄膜的Al组分

ＡｌＧａＮ／ＧａＮ异质结兰光激光器和发光管近年来得到很大的发展．高速和高功率的ＡｌＧａＮ／ＧａＮ异质结场效应管（ＨＦＥＴ）的研究也得到很大的重视．ＡｌＧａＮ 薄层中的Ａｌ组分是决定此类器件的设计和性能的一个重要参量． 传统的测量组分的方法如ＸＰＳ和Ａｕｇｅｒ等方法需要大型的仪器,而且大多数方法是破坏性的,注意到ＡｌＧａＮ的禁带宽度Ｅｇ和Ａｌ组分有直接的关系,可以通过光学方法先测出Ｅｇ,用下式推算出Ａｌ的组分： Ｅｇ（ＡｌＧａＮ）＝ Ｅｇ（ＧａＮ）（１－ｘ）＋Ｅｇ（ＡｌＮ）ｘ－ｂｘ（１－ｘ）．其中ｘ是…     

基于盲信号分离算法的立体声回波抵消的研究

当处理混合语音信号时,传统的立体声回波抵消技术不具备修正参数的能力.因此,传统的立体声回波抵消技术对于信号传输的可靠性存在很大的问题,论文中,我们提出一种基于盲信号分离方法(BSS)的立体声回波抵消技术.在我们提出的系统中,我们通过分离回波信号和说话人的语音信号来达到移除回波信号的目的.结果证明,本方法对于传输信号的可靠性有明显的提高.     

Metabolic Regulation of Tumor Microenvironment with Biohybrid Bacterial Bioreactor for Enhanced Cancer Chemo-Immunotherapy

Immunogenic cell death (ICD) induced by specific chemotherapeutic agents is often hampered by the immunosuppressive tumor microenvironment (TME). Here, a bacterial bioreactor E@Fe-DOX, is developed, to enhance ICD-mediated antitumor immunity by in situ manipulation of tumor metabolism-immune interactions. The E@Fe-DOX bioreactor is constructed by depositing doxorubicin-loaded iron-polyphenol nanoparticles on Eubacterium hallii, which can specifically target hypoxic tumor regions and release doxorubicin and Fe³⁺ to induce ICD. In addition, Eubacterium hallii can continuously convert intratumoral lactate to butyrate, which inhibits the polarization of pro-tumoral M2-like macrophages and improves the function of tumor-infiltrating cytotoxic T cells. Furthermore, E@Fe-DOX promotes the formation of immune cell-aggregated tertiary lymph structures (TLS) to augment ICD-induced antitumor immunity. In murine tumor models, E@Fe-DOX significantly inhibits tumor growth and enhances immune checkpoint blockade (ICB) therapy. Overall, the developed living biomaterial offers a promising strategy to potentiate cancer chemo-immunotherapy by continuously regulating the intratumoral immuno-metabolic microenvironment.