氧化铝增强的PdSe2/Si异质结光电探测器

为了降低暗电流,通过原子层沉积(ALD)生长了一层氧化铝(Al₂O₃)隧穿层,制备了PdSe₂/Al₂O₃/Si异质结光电探测器.通过优化Al₂O₃层的厚度,使得该探测器实现了高速和宽光谱响应.研究结果表明,在波长为808 nm的光照射和-2 V偏压下,所制备的光电探测器与未生长Al₂O₃的器件相比,暗电流降低了约3个数量级,器件的光响应度达到了约为0.31 A/W,对应的比探测率约为2.5×10¹² Jones,器件在零偏压下表现出明显的自驱动效应.经过循环测试1 200次后,器件保持良好的光响应.器件响应的上升时间和下降时间分别为7.1和15.6μs.结果表明,在二维层状半导体材料与Si之间引入Al₂O₃隧穿层,可以有效地降低器件的暗电流,有利于高性能的Si基光电探测器的制备.     

机载脉冲多普勒雷达单目标跟踪系统仿真

单目标跟踪是机载PD雷达的一种重要的工作模式.从机载PD雷达的实际模型出发,对整个跟踪系统建立了比较准确和完整的仿真模型.仿真中距离门和速度门可以动态调整,角度跟踪采用四波束的比幅和差单脉冲,数据处理用卡尔曼滤波器实现对目标四维的动态跟踪.最后结合具体实例进行了系统仿真,结果表明可以获得比较高的稳态跟踪精度.     

基于DSP/BIOS的FIR数字滤波器设计与实现

用可编程DSP器件实现数字滤波,通过修改滤波器参数可方便地改变滤波器的特性.以TMS320F2812数字信号处理器为核心,将滤波器算法作为DSP/BIOS的任务来实现,可方便地实现多任务系统.详细介绍一种基于DSP/BIOS的软件开发过程,并在DSK2812平台上实现数字滤波器的开发实例,对需进行数字信号处理的多任务软件开发具有一定的参考价值.     

"互联网+"下的智慧工地

随着社会生产力的不断发展,传统工程建设领域因其自身理念的落后,行业整体缺乏先进的互联网管理技术,在工程进程监督、质量检测、人员调配方面缺乏实时的分析手段,难以满足快速发展的需求."互联网+"理念与传统建设工程领域的深度融合,赋予传统工程建设领域以"智慧",利用物联网、云计算、BIM等信息化手段,对施工过程中人员、视频、质量、生产、环境等数据进行采集,最终实现互联协同、智能生产、科学管理等功能的智能化工程建设.     

锂离子电池石墨负极材料掺杂碳纳米管研究

采用低速球磨法在石墨中掺杂多壁碳纳米管,制成负极极片,在真空手套箱中组装成CR2025型扣式模拟电池。测试了其充放电性能及循环性能,研究了多壁碳纳米管的加入对石墨负极材料的影响。实验结果表明:碳纳米管的加入使得材料具有更优良的充放电性能,在常温0.2 C充放电条件下,复合材料首次放电比容量达到650 m Ah/g,首次充电比容量为385 m Ah/g,循环40次后,比容量损失率仅约为3.8%。     

信号管设置对直接作用调压器静态特性的影响

分析信号管的不同设置对直接作用式调压器静态特性的影响,提出了通过改进信号管的设置来优化调压器静态特性的建议。     

基于有限元法的顺层岩质边坡锚杆加固稳定性分析

结合某道路顺层岩质高切边坡实例,运用大型有限元软件MIDAS/GTS建立顺层岩质边坡的平面应变二维模型,基于有限元强度折减法,对锚杆加固前后的边坡稳定性进行了研究,主要分析了锚杆加固前后边坡位移、塑性破坏区以及安全系数的变化;同时着重讨论了锚固长度、锚杆间距、倾角等因素对边坡整体稳定性的影响,对影响边坡整体稳定性的因素进行了敏感性研究,分析了各因素与边坡安全系数之间的函数曲线关系。     

Cerebral Hyperperfusion after Revascularization Inhibits Development of Cerebral Ischemic Lesions Due to Artery-to-Artery Emboli during Carotid Exposure in Endarterectomy for Patients with Preoperative Cerebral Hemodynamic Insufficiency: Revisiting the “Impaired Clearance of Emboli” Concept

The purpose of the present study was to determine whether cerebral hyperperfusion after revascularization inhibits development of cerebral ischemic lesions due to artery-to-artery emboli during exposure of the carotid arteries in carotid endarterectomy (CEA). In patients undergoing CEA for internal carotid artery stenosis (≥70%), cerebral blood flow (CBF) was measured using single-photon emission computed tomography (SPECT) before and immediately after CEA. Microembolic signals (MES) were identified using transcranial Doppler during carotid exposure. Diffusion-weighted magnetic resonance imaging (DWI) was performed within 24 h after surgery. Of 32 patients with a combination of reduced cerebrovascular reactivity to acetazolamide on preoperative brain perfusion SPECT and MES during carotid exposure, 14 (44%) showed cerebral hyperperfusion (defined as postoperative CBF increase ≥100% compared with preoperative values), and 16 (50%) developed DWI-characterized postoperative cerebral ischemic lesions. Postoperative cerebral hyperperfusion was significantly associated with the absence of DWI-characterized postoperative cerebral ischemic lesions (95% confidence interval, 0.001–0.179; p = 0.0009). These data suggest that cerebral hyperperfusion after revascularization inhibits development of cerebral ischemic lesions due to artery-to-artery emboli during carotid exposure in CEA, supporting the “impaired clearance of emboli” concept. Blood pressure elevation following carotid declamping would be effective when embolism not accompanied by cerebral hyperperfusion occurs during CEA.