基于多尺度特征融合双U型皮肤病变分割算法

针对皮肤病分割问题中皮肤病变区域大小不一且形状各异问题,提出一种基于多尺度特征融合的双U型皮肤病分割算法.该算法由粗分U型网络和细分U型网络两部分组成.首先粗分U型网络编码部分采用预训练VGG-19模型对相关特征进行多尺度特征提取;在解码阶段利用改进注意力残差块将底层与高层信息进行有效的映射融合,得到初步的Mask;然后将初步生成的Mask与原图像聚合,并输入多路特征提取编码器中进行二次特征蒸馏;而细分U型网络解码器同时与粗分U型网络编码部分和细分U型网络的编码部分特征映射进行融合,保证网络可以聚合更多的有效特征;最后利用Focal Tversky损失函数进一步提升分割效果.实验表明,所提算法在ISBI2016数据集上实验分割精度为96.11％、敏感度为93.59％、特异性为97.10％、Dice系数为93.14％、Jaccard系数为87.17％,能够有效地分割皮肤病病变区域.     

基于区块链的侦查机器人实时避障与航线控制

为弥补侦查机器人行进灵活性不足的缺陷,降低无故运动碰撞事件的发生几率,提出基于区块链的侦查机器人实时避障与航线控制算法;利用超声信号处理电路,提取可供直接应用的侦查运动节点,联合已完成配置的MoveIt避障程序,实现对侦查机器人的实时避障运动规划;在此基础上,设置LQR控制器,在控制机器人侦查航速的同时,建立必要运动操纵方程,完成对侦查机器人的运动航线控制,提升与运动设备元件相关的行进灵活性;完善P2P网络平台,以待交互的运动数据作为处理支持条件,将所有侦查信息封装至同一区块组织中,完成基于区块链的避障控制原理研究,实现侦查机器人实时避障与航线控制算法的搭建;对比实验结果表明,应用基于区块链的控制算法后,C-Space参数极值超过8.0,RRT灵敏度也提升至75%,实现了对侦查机器人的灵活性行进控制,有效抑制了无故运动碰撞事件的出现。     

基于扩张状态观测器的反馈线性化无人飞行器姿态控制

随着集成电子等技术逐渐成熟,无人飞行器得到了广泛的关注和应用;其中,由于飞行器在飞行阶段具有高响应速度、耦合动力学和非线性等特点,使其在飞行阶段的姿态控制成为该领域重点研究的方向之一;针对该研究方向,文章提出了一种基于反步法技术的反馈线性化无人飞行器姿态跟踪控制方案来解决其在受到环境干扰的条件下可以精准跟踪姿态角度的问题;在该方法中,设计了反步法技术拆分简化模型和反馈线性化减少调节参数,并利用扩张状态观测器(ESO)来对扰动进行估计和补偿,同时给出了ESO的收敛性和闭环系统的稳定性来证明该方法的可实施性;最后给出了仿真结果,验证了该方法在干扰的环境下仍可以精准控制无人飞行器姿态。     

机载显控设备测试性设计

机载显控设备作为人机交互终端,具有数据处理及与人交互的工作特点,采用传统BIT(机内测试)测试性设计方法,故障检测率指标难以满足用户要求;根据其设备组成和主要功能,结合FMECA(失效模式影响及危害度分析)分析结果,提出BIT检测与人工检测相结合的方式开展测试性设计,通过TADS软件建立设备测试性模型并进行了计算和分析,设备故障检测率由74.72%有效提高到93.26%,以较小代价实现了用户要求;为其他人机交互机载设备测试性设计提供参考,具有较好的工程实用价值。     

计算机网络与商务英语教学整合模式探讨

随着经济以及科技的高速发展,国际之间的交流和合作越来越频繁。在商务英语教学中,教师不能仅仅简单地为学生讲述理论性的知识,还需要为学生提供更多的实践机会,同时借助计算机网络技术,拓展学生的英语视野,不断夯实学生的英语水平。本文探究了计算机网络应用在商务英语中的重要性,并提出了计算机网络和商务英语整合的相关对策,以便强化商务英语的教学效率。     

Synthesis and characterization of triangular-pyramidal bismuth oxide via a one-step chemical precipitation route

Triangular-pyramidal ω-Bi_2O_3 is successfully synthesized via a one-step wet-chemical method.XRD,SEM,and UV-vis have been employed to characterize the as-prepared samples.Structural characterization by XRD confirms the formation of triclinic ω-Bi_2O_3 with high purity.The well-defined flowerlike Bi_2O_3 structures consisted of many triangular-pyramids are formed.Preparative parameters,such as concentration of PEG 6000,have great effects on the morphology and the particle size.The obvious absorption edge for ω-Bi_2O_3 powder is located at about 493 nm,which corresponds to the optical band gap energy of2.73 eV.     

High-Precision Wideband Phase-Derived Velocity Measurement for Micro-Motion Extraction

A phase-derived velocity measurement method is proposed in a wideband coherent system, based on a precise echo model considering the inner pulse Doppler effect caused by fast moving targets. The Cramer-Rao low band of velocity measurement precision is deduced, demonstrating the high precision of the proposed method. Simulations and out-field experiments further validate the effectiveness of the proposed method in high-precision measurement and micro-motion extraction for targets with weak reflection intensity. Compared with the long-time integration approaches for velocity measurement, the phase-derived method is easy to implement and meets the requirement for high data rate, which makes it suitable for micro-motion feature extraction in wideband systems.     

Investigations on Structured Polyamide for Laser Sintered Body Armor

Stab resistance body armor (SRBA) is essential in protecting people from knife injuries. The protective parts of traditional SRBA are made of multi-layered ultra-high molecular weight polyethylene (UHMWPE), which causes heavy heat stress for people wearing it. The protective parts of SRBA manufactured using laser sintering (LS) 3D printing technology provide high manufacturing flexibility and low weight. Two different structures, plain plate and pyramid-structured plate, were investigated. The pyramid structure showed much higher stab resistance property then the plain plate, because of the angle and thickness effects. This is the first effort applying the LS technology and polyamide (PA) material (PA 3200) on SRBA. By applying the pyramid structure on the protective layer of the SRBA, the total weight could reduce 30%-40%.     

对称加载作用下单箱双室组合结构的剪滞效应特性与试验研究

对于箱型组合结构,由于应力分布不均,极易导致翼板及底板发生剪切变形,从而对结构安全不利。为了深入探讨单箱双室组合结构中剪滞效应的机理,根据该类结构的受力变形特点,建立混凝土翼板和单箱双室钢梁的纵向翘曲位移模式,得到了控制微分方程及其边界条件,并推导出了在对称荷载作用下单箱双室组合结构的应变及挠度的解析表达式。开展了室内足尺寸模型试验,与剪滞效应理论进行了对比研究,应变、挠度计算值的最大相对误差分别达到15.32%和16.97%。可为该类结构中剪滞效应研究及单箱双室组合结构的工程设计、后期加固提供一定的参考。     

Performance Comparison of Long-Wave Infrared Imaging Spectrometer Between Dyson Form and Offner Form

In view of the difficulties in traditional long-wave infrared imaging spectrometer which is hard to realize a high signal-to-noise ratio and miniaturization as well under the weak remote sensing signal,Offner convex grating spectrometer and Dyson concave grating spectrometer,both having concentric structure,are designed and analyzed in the band of 8-12 μm. The diffraction angle expressions of the two spectrometers are obtained and the diffraction characteristics are acquired. Both of the spectrometers are designed in Zemax environment under different F-numbers and different grating constants with the same slit,spatial resolution,spectral resolution and detector. The results show that Dyson grating spectrometer possesses the advantages of higher throughput and smaller volume, and Offner grating spectrometer possesses the advantage of more accessible material and the absence of chromatic aberration. The differences between Dyson form and Offner form show that the former is a better choice in the long-wave infrared imaging spectrometer.