随钻测井数据声波遥传系统研究

随钻测井数据传输是实现智能化钻井的荚键技术之一,声波遥传技术是利用沿钻柱系统传播的弹性波为载波,将测量数据传输到地面的一种随钻数据传输技术,是一种新兴的、非常有发展前途的随钻数据遥传技术。然而,钻井过程中由钻井设备、泥浆的循环等产生的声波噪声以及信号在介质中传播的衰减吸收,特别是钻杆接头的高反射性,使得钻柱的脉冲响应持续达数酉毫秒,这将造成严重的码间干扰,并最终导致信道的传输能力的大幅下降。针对这一难题,该文在深入分析钻柱系统的声传播特性的基础上,提出基于SC—FDE技术的声波无线传输通信系统模型,并研究适合于声波传输信道特性的信道编译码技术以及随钻数据的调制解调技术,降低误码率、提高传输的可靠性。     

基于FPGA密集假目标干扰的实现

在现代电子战中,应对新体制雷达、雷达干扰机转向采用欺骗性干扰方式,结合DRFM的机理,介绍了可控变间隔的密集假目标产生机理,基于FPGA内部IP核 FIFO 产生密集假目标,通过控制FIFO的存储深度来实现假目标的延迟时间;通过开关控制假目标的输出数量。仿真分析了假目标产生机理的正确性,同时验证了密集假目标产生的硬件可实现性,并给出了硬件实现假目标调幅调频的方法,为相关雷达干扰机硬件实现提供了参考。     

基于非下采样Contourlet的熵测度图像融合算法

活性测度是图像融合过程中的重要衡量工具.通过其提取的某种特征信息,来决定哪幅输入图像的特征更为明显.在基于多分辨率分解的融合算法中,常用的活性测度只考虑各层高频子带系数本身,忽略了低频系数所提供的信息.考虑到综合高、低频系数对于活性测度的影响,基于非下采样Contourlet变换良好的平移不变性、多方向等特性,提出了一...     

Synthesis and Characterization of Polythiophene/Bi2Te3 Nanocomposite Thermoelectric Material

To achieve low thermal conductivity, polythiophene (PTh)/bismuth telluride (Bi₂Te₃) nanocomposite has been prepared by spark plasma sintering using a mixture of nanosized Bi₂Te₃ and PTh powders. Bi₂Te₃ powder with spherical-shaped particles of 30 nm diameter and PTh nanosheet powder were first prepared by hydrothermal synthesis and chemical oxidation, respectively. X-ray diffraction analysis and scanning electron microscopy observations revealed that the hybrid composite consists of PTh nanosheets and spherical Bi₂Te₃. The organic PTh acts as an adhesive in the composite. Transport measurements showed that the PTh in the Bi₂Te₃ matrix can reduce its thermal conductivity significantly, but also dramatically reduces its electrical conductivity. As a result, the figure of merit of the composite is lower than that of pure Bi₂Te₃ prepared under the same conditions. The maximum value of ZT for the sample with 5% PTh (by weight) was 0.18 at 473 K, which is rather high compared with other polymer/inorganic thermoelectric material composites.     

典型微区环境下信道特性的仿真结果

多径效应产生的扩散效应一直是无线信道研究的主要问题。作者利用自行开发的无线信道仿真软件对微区环境下的主要信道特性进行了大量的仿真，得到了典型微区环境下的传播损耗，时延扩展和角度扩散等主要信道特性的描述。     

复合补偿在印制板尺寸变形修正中的应用

印制板生产过程中,基材不可避免会出现平面上的尺寸涨缩变形,业内一般对此种变形进行经验性或基于试制的结果进行反向预补偿,此种预补偿有一定概率达不到预期效果.文章提出通过分区抓取PCB板件的几何中心,并在模拟平面二维线性形变的基础上对PCB成品尺寸变形进行复合补偿,可以有效解决上述问题.     

宽带接入技术的最新进展

本文对当前宽带接入技术的总体情况以及该领域的技术亮点进行了介绍,并具体描述了DSL、光纤和无线接入技术的当前发展情况及具体技术(如ADSL2/ADSL2 、EPON/GPON、IEEE 802.16)的技术特点和市场定位,最后提出了宽带接入技术未来的发展趋势.     

ISO/TS16949质量策划的有效手段——跨部门小组

本文论述了ISO/TS16949的跨部门小组组建的目的,小组的组成、职责,以及跨部门工作小组在产品质量控制中所起的作用.     

多注太赫兹折叠波导行波管的设计与模拟

为解决太赫兹(THz)行波管工作电流过小、输出功率低等问题,提出了基模多注工作模式的折叠波导行波管(TWT)。首先,获得了基模多注折叠波导色散特性;然后,对基模多注折叠波导的传输特性进行了模拟计算;最后,完成了0.14 THz基模多注折叠波导行波管的注波互作用特性分析。电子注参数为12 m A,15.75 k V时,获得的3 d B带宽为25 GHz(128 GHz~153 GHz),最大增益为33.61 d B,最大峰值功率为23 W;电子注参数为30 m A,15.75 k V时,在0.14 THz处获得了38 d B增益,最大脉冲输出功率为63.1 W。该方法能够有效增大THz行波管的工作电流,提高互作用增益及效率、3 d B带宽、输出功率;在增益相同时,基模多注行波管可以做得更短、更紧凑。     

Review of roll-to-roll fabrication techniques for colloidal quantum dot solar cells

Colloidal quantum dots (CQDs) are of great interest to photovoltaic (PV) technologies as they possess the benefits of solution-processability, size-tunability, and roll-to-roll manufacturability, as well as unique capabilities to harvest near-infrared (NIR) radiation. During the last decade, lab-scale CQD solar cells have achieved rapid improvement in the power conversion efficiency (PCE) from ~1% to 18%, which will potentially exceed 20% in the next few years and approach the performance of other PV technologies, such as perovskite solar cells and organic solar cells. In the meanwhile, CQD solar cells exhibit long lifetimes either under shelf storage or continuous operation, making them highly attractive to industry. However, in order to meet the industrial requirements, mass production techniques are necessary to scale up the fabrication of those lab devices into large-area PV modules, such as roll-to-toll coating. This paper reviews the recent developments of large-area CQD solar cells with a focus on various fabrication methods and their principles. It covers the progress of typical large-area coating techniques, including spray coating, blade coating, dip coating, and slot-die coating. It also discusses next steps and new strategies to accomplish the ultimate goal of the low-cost large-area fabrication of CQD solar cells and emphasizes how artificial intelligence or machine learning could facilitate the developments of CQD solar cell research.