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41.
基于磁/惯性传感器旋转弹体定姿的Kalman滤波器设计 总被引：1，自引：0，他引：1
微惯性传感器精度较低,其漂移会引起很大的姿态误差,不能提供长时间稳定姿态;磁传感器组合的姿态角误差不随时间累积但姿态角更新速度慢。针对这一问题提出了利用磁/惯性传感器构建低成本姿态探测系统的方案,设计了Kalman滤波器融合二者信息——以磁传感器解算的姿态角和等效旋转矢量法解算的姿态角之差作为观测量,以惯性传感器的漂移和姿态误差角作为状态变量,整个解算过程无需使用地磁场强度。仿真结果表明了该算法的有效性,二者组合定姿可实现高精度的姿态测量。 相似文献
42.
采用水热-煅烧法制备Cd2SnO4,之后通过超声混合法得到一系列MoS2/Cd2SnO4复合材料。采用X射线衍射、扫描电子显微镜、X射线光电子能谱对Cd2SnO4和一系列MoS2/Cd2SnO4复合材料进行结构和形貌的表征。研究了MoS2掺杂量对于MoS2/Cd2SnO4复合材料的气敏性能影响。实验结果表明,当MoS2与Cd2SnO4的质量比为2.5%,MoS2/Cd2SnO4复合材料制备的气敏元件在170 ℃时对浓度为100 μL·L-1的甲醛气体的灵敏度为40.0,最低检测限为0.1 μL·L-1。 相似文献
43.
BU Zehua;MAO Bangning;SI Zhaopeng;GONG Huaping;XU Ben;KANG Juan;LI Yi;ZHAO Chunliu 《光子学报》2022,51(11):79-87
With the rapid development of the Internet of Things era, the perception and acquisition of all kinds of external information is becoming increasingly important. Traditional monitoring and warning technologies such as manual inspection, video surveillance, infrared detection, and microwave detection have been widely used in various fields. Although these technologies have succeeded, they are expensive, environmentally sensitive, and cannot be monitored over long distances. To realize real-time and environment-free long-distance monitoring, distributed optical fiber sensing technology has developed rapidly in recent years. Distributed optical fiber sensing uses the whole optical fiber as the signal's transmission medium and sensing unit. When external factors act on the optical fiber, the light wave transmitted in it is modulated accordingly, and its light intensity, frequency, phase or polarization state, and other parameters will change accordingly. Distributed optical fiber sensing has the advantages of flexible layout, high cost performance and wide measurement range. Compared with traditional methods, distributed optical fiber sensing realizes large-scale measurement at a lower cost. As an important branch of distributed optical fiber sensor, phase sensitive optical-time domain reflectometer has the advantages of high sensitivity, high resolution and simple structure. At present, φ-OTDR plays an important role in many applications, such as structural crack detection, railway monitoring, traffic flow detection, vehicle detection and intrusion detection. With the development of modern productive forces and the diversification of life scenes, simple vibration location and signal demodulation cannot meet the actual needs and user needs. Random interference in nature （such as thunderstorm, wind, hail, etc.）, passing vehicles and moving personnel will interfere with the accurate recognition of intrusion signals, increasing the false alarm rate. It is hoped that the type of vibration signal can be obtained at the same time as the location of the vibration signal, so as to replace manual inspection more intelligently. Compared with traditional monitoring methods, phase sensitive optical-time domain reflectometer system has greater advantages in real-time performance and convenience. At the same time, compared with video surveillance, phase sensitive optical-time domain reflectometer system is more covert, has strong resistance to external electromagnetic and other interference signals, and has the advantages of low cost, wide range and continuity. Therefore, it is of great significance to classify and identify vibration signals, identify the types of vibration signals, and study related identification algorithms to improve the identification accuracy and response speed of vibration signals, which are of great significance to the monitoring occasions in the fields of road traffic and border security. In view of the phase-sensitive optical time domain reflectometer distributed optical fiber sensing system has difficulties in real-time performance and accuracy of signal recognition. A method based on wavelet packet decomposition and support vector machine is presented. The energy feature vector is extracted by the wavelet packet decomposition of the signal as the input samples of the support vector machine, and the energy distribution trend of different signals is analyzed. A total of 800 experimental samples of knock, shake, walk and noise signals were trained. The recognition effect was evaluated by four evaluation indexes： accuracy rate, recall rate, F1 value and accuracy. The experimental results show that the precision rate, recall rate and F1 value of the knocking signal are 94.12%, 96% and 95.05%, respectively; the precision rate, recall rate and F1 value of the shaking signal are 95.92%, 94% and 94.95%, respectively; The precision rate, recall rate and F1 value of walking signal and noise signal are all 100%. The overall recognition accuracy is above 97%. The method improves the recognition result accuracy and real-time performance in the signal recognition of phase sensitive optical-time domain reflectometer system. 相似文献
44.
活性氧簇(ROS), 如过氧化氢, 在生物体内的各种生理和病理过程中发挥着重要作用. 生物体内活性氧簇水平的异常与多种疾病(炎症、 肿瘤和器官损伤等)密切相关, 使ROS监测成为研究和诊断这些疾病的重要工具. 目前, 实现活体内深组织中的活性氧簇成像仍然面临挑战. 本文设计并合成了一种响应型的19F磁共振成像(MRI)探针(Gd-DPBF), 并将其用于实现对活体内通用活性氧簇的检测和成像. 该探针由钆螯合物通过活性氧簇响应的芳香硼酸酯键与含氟砌块相连接构成. 体外和体内成像实验结果证实, 该探针可以实现在活体荷瘤小鼠中针对肿瘤中高表达的活性氧进行检测和成像, 展示了其在生物体内对活性氧簇相关生理过程进行深组织、 零生物背景成像方面的潜力. 相似文献
45.
Exploring the discrete complexes with multi-step coloration is still a challenge in the field of electron transfer photochromic materials. Herein, we synthesized a series of dinuclear Ln-diphosphonate compounds[Ln=Dy(1); Gd(2); Tb(3); Y(4)] with a remarkably and reversibly photoactive coloration phenomenon. These compounds showed two-step coloration behavior, which were the first discrete architectures in the reported electron transfer photochromic complexes. This two-step coloration phenomenon was originated from the large distortion of H3-TPT acceptors, which in turn reduced the π-conjugation of electron acceptors and slowed the decay process of electron transfer. The photogenerated stable doublet radicals originated from electron transfer from diphosphonate donor to polypyridine acceptor in these complexes were detected by UV-Vis and electron spin resonance(ESR) spectra. Furthermore, the photogenerated radicals were estimated by direct current magnetic susceptibilities and variable temperature ESR spectra, suggesting the doublet radicals in the dinuclear structure for all the compounds. This work revealed a series of discrete phosphonate-based systems with a multi-step coloration process, providing a new pathway for designing multicolor photochromic materials with potential photoswitching or other applications. 相似文献
46.
Binding energies of ionized donor–exciton complexes in crystals of CdSe, CdTe, and ZnSe are calculated using the most realistic effective potentials available for the electron–hole interaction. 相似文献
47.
In order to better realize sound echo recognition of underwater materials with heavily uneven surface,a features ion method based on the theory of signal sparse decomposition has been proposed.Instead of the common time frequency dictionary,sets of training echo samples are used directly as dictionary to realize echo sparse decomposition under L1 optimization and a kind of energy features of the echo.Experiments on three kinds of bottom materials including the Cobalt Crust show that the Fisher distribution with this method is superior to that of edge features and of Singular Value Decomposition （SVD） features in wavelet domain.It means no doubt that much better classification result of underwater bottom materials can be obtained with the proposed energy features than the other two.It is concluded that echo samples used as a dictionary is feasible and the class information of echo introduced by this dictionary can help to obtain better echo features. 相似文献
48.
This paper reports a study of complex focussing acoustic fieldsof a convex phased array probe widely used in ultrasonic diagnosticB-scanner.The time delay necessary for electronic focussing and forgeometric focussing of complex focussing is given.By means ofHelmholtz‘s integral formula,the expressions of acoustic fields wereobtained for the electronic focussing and complex focussing.With simpson‘snumerical integral,a great deal of computations was carried out withan 86 /330 computer.By means of using different parameters,an optimum focal range and beam width of a 4 sequences electronic andcomplex focussing acoustic system was selected.With an EUB-40ultrasound diagnostic B-scanner produced by the Hitachi company,the lateral focussing acoustic field and lateral resolution in an echoic tankwere photographed by latticing method and the experimental result is con-sistent with the theory. 相似文献
49.
P. Petelenz 《physica status solidi b》1976,73(2):565-573
An effective electron-hole interaction is investigated which arises due to the one-particle exciton dissociation matrix elements of the Hamiltonian. Fröhlich-type unitary transformation is adopted and the transformed Hamiltonian is discussed. The exciton energy is renormalized. The sign and absolute value of the effective electron-hole interaction is revealed to depend on the energy difference between the neutral exciton and charge transfer states. The influence of the vibronic coupling is also investigated. 相似文献
50.
用中和法合成了氨基酸离子液体1-乙基-3-甲基咪唑丙氨酸([C2mim][Ala]),并利用恒温环境的溶解反应热量计,在(288.15±0.01) K-(308.15±0.01) K温度范围内每隔5 K,测定不同质量摩尔浓度离子液体在水中的溶解焓(ΔsolHmθ).根据Archer的方法,通过线性拟合得到了该离子液体的标准摩尔溶解焓(Δsol),并计算了其相对表观摩尔溶解焓(ΦL).在298.15 K下,根据Glasser经验方法得到了格子能UPOT = 566 kJ·mol-1,并计算了其阴阳离子水化焓值(ΔH+ + ΔH-) = -620 kJ·mol-1及阴离子水化焓ΔH-([Ala]-) = -387 kJ·mol-1.此外,估算了[C2mim][Ala]水溶液的热容(Cp(sol))和表观摩尔热容(ΦCp). 相似文献