Accuracy analysis and stabilization design of the Fabry–Perot frequency discriminator in double-edge wind lidars

The measurement error of a double-edge wind lidar caused by a disturbed Fabry–Perot interferometer (FPI) is analyzed. Several error sources such as air pressure variations, temperature changes, and mechanical vibrations are considered in the measurement-error model. The simulation results show that a double-edge wind lidar is so sensitive to environmental variations that the measurement error reaches ±60 m/s if the FPI is not stabilized. In order to compensate the external disturbance acting on the FPI, a nonlinear proportional–integral–derivative (PID) control scheme is designed based on the transmission measurement of the calibration channel. An arc tangent function is used to improve the feedback gain of the usual PID control design. The results show that with the new controller the measurement accuracy of the wind lidar can be improved 4–5 times in comparison with the usual control design, and the range of the measurement error is only ±3 m/s.     

新大线同沟敷设热力分析

针对新大线同沟敷设管道,采用非结构化有限容积法,分析了不同的物性条件下,常温输送原油对加热输送原油的热力影响.     

基于红外光谱研究沥青燃烧机理和有害气体成分分析

利用Rosemount气体分析仪和定碳炉搭建起固定床燃烧反应试验平台,通过红外光谱分析技术定量分析沥青及其胶浆在高升温速率条件下燃烧反应的有毒气态产物成分、及其释放规律。研究表明,在高升温速率、近等温条件下,沥青及胶浆的燃烧过程可近似分为活泼挥发组分析出燃烧、二次挥发析出结合残炭燃烧两个阶段,其主要气态产物为CO₂,CO,NO,NO₂及SO₂。沥青材料中活泼挥发组分含量是影响燃烧气态产物释放规律的关键因素之一,减少沥青材料中活泼挥发组分的含量可有效降低燃烧气态产物的生成、尤其是CO的产生。     

新方法精确测量凸透镜焦距

凸透镜在光学应用中有很大的作用,而它焦距的测定方法有很多。本文应用分光计、可调狭缝设计一种新方法精确测量凸透镜的焦距。     

某向心式蒸汽透平的气动设计与数值研究

本文针对太阳能热发电过程中蒸汽流量小、焓降高的特点设计了一种部分进汽的向心式蒸汽透平。所设计的蒸汽透平在流量仅为2.33 kg/s、压比为3.36的工况下仍有较高的效率。通过三维数值模拟的方法分析了导叶和叶轮内部流动特性,探讨了部分进汽对通道流通能力及总效率的影响。     

Manganese doping effects on interband electronic transitions,lattice vibrations,and dielectric functions of perovskite-type Ba<Subscript>0.4</Subscript>Sr<Subscript>0.6</Subscript>TiO<Subscript>3</Subscript> ferroelectric ceramics

The Ba_0.4Sr_0.6−x Mn _x TiO₃ (BSMT) ceramics with different Mn composition (from 1% to 10%) have been prepared via the conventional solid-state reaction sintering. The X-ray diffraction analysis shows that the ceramics are polycrystalline with the single perovskite phase. The lattice vibrations and optical properties have been investigated using Raman scattering, spectroscopic ellipsometry (SE), and infrared reflectance spectra. It was found that the optical bandgap for the BSMT ceramics is varied between 3.40 and 3.65 eV. The three first-order Raman-active phonon modes can be observed, and the frequency of the A ₁(LO₃)/E(LO) mode shows a blue shift of 8 cm⁻¹ with the Mn composition, which can be attributed to the distortion of the TiO₆ octahedron. With increasing Mn composition, the frequency of the infrared-active TO₄ mode decreases from 532 to 520 cm⁻¹, owing to the local variation of the lattice constant induced by the Mn incorporation. Moreover, the optical functions of the ceramics from the far-infrared to ultraviolet region are obtained based on the SE and reflectance spectra, which is useful for the potential applications in ferroelectric-based optoelectronic devices.     

对数似然图像分割的快速主动轮廓跟踪算法

针对跟踪目标尺度变化问题,提出了基于灰度对数似然图像分割的快速主动轮廓跟踪算法。改进的主动轮廓跟踪算法将根据以目标与背景的颜色差异而建立的对数似然图对图像进行阈值分割和数学形态学处理,再将Kalman滤波器结合到主动轮廓跟踪算法进行目标跟踪。改进的主动轮廓跟踪算法对目标分割准确,轮廓特征显著,跟踪效果稳定,算法能很好地适应跟踪目标尺度变化。通过Kalman滤波器对目标位置点的预测减少了主动轮廓跟踪算法收敛的迭代次数,使算法的运算效率提高了33%左右。     

物理教育研究评估

科学的定性及定量评估方法是物理教育研究重要的研究手段.目前国际通用的教育评估测试,根据测试目标的不同,可分为多种类型:学习内容调查、学习态度调查和科学分析能力调查等.我们已将本文中介绍的部分评估测试应用于国际教育研究领域.     

多种通信手段在遇险救生体系中的应用研究

我国海域辽阔,各类船只的水上航行和作业安全密切关系到生命和财产的安全,需要可靠保障。由于海上险情发生的随机性和突发性,岸上险情监视力量必须全时、全天候地开设险情通信通道,接收海上遇险对象的遇险呼救信号并及时对遇险信息进行处理。因此,岸基必须建设遇险救生信息系统并规定必要的信息传输流程,保障险情报知通信的顺利完成。文章简要分析了目前海上救生的通信现状,对常用通信手段进行了分析与介绍,并提出了一种整合各通信手段的设计方法,实现了多种通信手段的综合使用以及统一调度,大幅提升险情信息的传输和处理效率,提高险情信息的保密性,为救援工作提供了精确可靠的问责手段。