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141.
近距侧爆情况下马蹄形隧道动态响应特点的研究 总被引：21，自引：2，他引：19
在数值模拟和动光弹试验研究的基础上 ,对马蹄形隧道在邻近爆破作用下的动态响应特点进行了分析 ,并在综合考虑入射应力波波长、隧道直径、爆源与隧道的相对距离的基础上 ,提出了隧道迎爆一侧的动应力集中因子的近似确定方法 ,为今后邻近隧道的爆破施工安全提供了有益的参考。 相似文献
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143.
以RDX为基的含铝炸药中铝粉粒度和氧化剂形态对加速金属能力的影响 总被引：3，自引：0，他引：3
利用激光速度干涉仪研究了含微米铝粉和纳米铝粉复合炸药加速金属平板的能力,结果表明纳米铝粉的引入能够获得更大的金属平板自由面速度,其反应时间比微米复合含铝炸药缩短35.1%。研究了氧化剂的形态对含铝炸药性能的影响,用物理化学手段获得的RDX/AP复合粒子复合粒子制作的含铝炸药加速金属平板的能力优于机械混合RDX/AP的含铝炸药,前者的反应时间也比后者短。此外,还研究了以富氧炸药取代RDX获得的含铝炸药的性能,结果表明其加速金属平板的速度比RDX/Al复合炸药提高10%。 相似文献
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李惠;贾晓卫;魏泽坤 《光子学报》2017,46(11):1125003
对不同氧化孔径尺寸的高速,低能耗的垂直腔面发射激光器（VCSEL）进行了相对强度噪声（RIN）分析.小氧化物尺寸孔径的VCSELs器件更适用于低能耗数据传输,且RIN特性与低能耗性能没有冲突.实验结果表明,适合低能耗、高温度稳定性工作的小氧化孔径VCSELs器件同时表现出较好的噪声性能.高速低能耗VCSEL能够满足32GFC光纤通道标准的RIN要求,在将来的高性能计算机应用中具有巨大优势. 相似文献
147.
该文采用非变性电喷雾质谱法(Nativeelectrosprayionizationmassspectrometry,ESI-MS)与分子对接模拟计算(MD)分别研究了1种溴代阻燃剂和2种羟基化代谢物,即3,5,3′,5′四溴4,4′二羟基基二苯砜(TBS)、4羟基2,2′,3,4′,5,5′,6八溴联苯醚(4OH-BDE-187)、6羟基2,2′,3,4,4′,5,5′八溴联苯醚(6OH-BDE-180)与甲状腺素运载蛋白(TTR)的相互作用情况。ESI-MS结果表明,在37℃及生理pH值条件下的醋酸铵缓冲溶液中,TBS与TTR蛋白可形成稳定的化学计量比为1∶1的复合物,4OH-BDE-187、6OH-BDE-180可与TTR蛋白分别形成稳定的化学计量比为1∶1和2∶1的复合物。通过分子对接模拟计算方法推测了上述3种配体与TTR可能的结合模型,发现3种配体与TTR的结合位点位于ASP-74残基附近。研究结果可为进一步了解溴代阻燃剂及其羟基化代谢产物体内的生物过程及毒性机制提供实验基础。 相似文献
148.
XUE Qingsheng;BAI Haoxuan;LU Fengqin;YANG Jingyao;LI Hui 《光子学报》2023,52(5):301-314
With the development of the hyperspectral imaging technology, it has been widely used and convinced as a useful detecting tool in many areas such as medical area, food safety and mineral exploration. But most of the hyperspectral imagers used nowadays are based on push-broom spectral imaging technology, which achieve spectral imaging through moving the spectral imager by scanning structure. The time resolution is sacrificed to obtain rather good spectral and spatial resolution in this kind of spectral imaging way. And that means the dynamic target and process can not be detected by this kind of hyperspectral imagers, so the application range of this kind technology is limited largely. Due to the defects mentioned above, a snapshot hyperspectral imager based on microlens array is developed in this paper. The principle of the instrument developed is introduced in this paper. Then the imaging principle of the microlens is introduced based on geometrical optics. The signal-to-noise calculation model of the hyperspectral imaging system based on microlens is then derived according to the imaging characteristics of this kind of system. Based on these theories derived above, the optical system is designed. The detector and the microlens were first determined before the optical design job begin. The detector has 2 048×2 048 pixels with a pixel size of 5.5 μm×5.5 μm . And the microlens array is composed of 100×100 microlens. The size of each microlens is 100 μm, and the focal length of the microlens is 0.5 mm. According to the microlens size and the detector size, the wavelength range of the whole system is determined as 500~700 nm. An objective lens is first designed, the F number of the objective is determined as 60 according to the calculation result, and the field of view of the objective lens is 36°.The objective lens has a telecentric feature on image side. Then the spectral imaging system is designed. The F number of the spectral imaging system is determined as 5 according to the F number of the microlens. A double amici prism is designed and used as the dispersion element in the spectral imaging system. The collimating lens and imaging lens in the spectral imaging system are symmetrical to eliminate the vertical aberration in the system and make the fabrication of the lens simpler. A simulation is taken after the design work has been finished. A prototype is set up in the laboratory according to the simulation result, and several performance verification experiments are taken to test the imaging and spectral performance of the system. The spatial and spectral calibration of the system are first taken. According to the calibration result, the monochromatic images of different bands can be extracted. To test the spectral resolution of the whole system, a mercury lamp is used to illuminate the system. And according to the test result, the spectral resolution of the system is 2.034 nm at 546.08 nm and 7.052 69 nm at 696.54 nm. A special target is used to test the spatial resolution of the whole system. According to the test result, the resolution of the whole system is 2.2 mm when the object distance is 1.1 m. Then a board with different color blocks and a standard white board are used as the target and detected by the whole system. Then the reflectance curves of different color blocks are calculated, which match the reflectance curves obtained by a commercial spectrometer. The test results show that the system has a good spectral and relatively good spatial detection capability. Comparing to the traditional push-broom spectral imager, the built system can improve the detecting efficiency of the spectral imaging detection, reduce the volume of the whole hyperspectral imaging system, and expand the application range of hyperspectral imaging technology. 相似文献
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150.
Wenhui FAN;Hui YAN;Xiaoqiang JIANG;Longchao CHEN;Zhuanping ZHENG;Jia LIU;Hui LI;Ling DING;Chao SONG 《光子学报》2022,51(7):51-89
Terahertz （THz） waves （0.1 THz ~ 10 THz, 1 THz = 1012 Hz） locate in the transitional region of the electromagnetic spectrum, between the classical electronics （radio, microwave and millimeter wave） and the photonics （infrared, visible, ultraviolet and x-ray）. As a kind of coherent measurement technology in THz frequency range, THz characteristic spectroscopy, with high sensitivity, rapidness and nondestructive testing as well as other unique advantages, has shown an attractive promising application prospect in detection, analysis and identification of biochemical molecules and materials. As the widely used broadband THz wave source, THz Photoconductive Antenna （THz-PCA） can emit broadband THz radiation. Therefore, as one of the promising THz emitters and detectors, THz-PCA has the advantages to overcome the defects confronted by other devices （e.g., low operation frequency, strict working condition and bulk size） and these unique advantages have made THz-PCA become the most commonly utilized THz sources in THz Time-Domain Spectroscopy （THz-TDS）. Although a variety of THz-PCAs are commercially available and become indispensable in many practical applications currently, the insufficient radiation THz power still hinder the further development of THz technologies based on THz-PCA. In order to further promote the research interests of THz-PCA, the working mechanism and some new research progress, technical challenges in the process of practical application and strategies of THz-PCA have to be discussed and analyzed. The underlying physical mechanism of the transient response in THz-PCA emitter and detector are investigated, as well as the influence of several parameters including the power intensity of femtosecond pump laser, the laser pulse duration and the carrier lifetime of the substrate material, are also analyzed based on theoretical models, which provide the technical foundation for designing the efficient THz-PCA. Moreover, a plenty of valuable research schemes have been proposed to develop the THz technologies based on THz-PCA in the past decades, including photoconductive materials and structure design of THz-PCA. To be specific, the sub-picosecond carrier life time of photoconductor can be realized by creating a massive density of defects, dislocations and scattering centers in the substrate material. As for structure design of THz-PCA, the previous researches on THz-PCA was mainly focused on the saturation effect at high pump power and the large aperture dipoles, dipole arrays and interdigitated electrodes structures have been investigated during the early stage. In the recent years, as the quick development of micro-nano fabrication technologies, the THz-PCA incorporated with plasmonic nanostructures and all-dielectric nanostructures have also been widely investigated for improving its performances.In this paper, the working principle and development status of THz-PCAs based on ultrashort pulsed laser are introduced, including theoretical models, substrate materials and different structures of photoconductive antennas. Furthermore, with the dramatic development of source and detector components, THz spectroscopy technology has been utilized in various fields such as chemical detection and substance identification, biomedical application and pharmaceutical industry. THz-TDS is the most commonly used technique in current commercial THz spectroscopy, which has attracted wide attention for its spectral fingerprint, high temporal-spatial resolution, noninvasive and nonionizing properties. Various important biomolecules, such as amino acids, nucleobases and saccharides reveal rich absorption features in THz range. It is verified that THz spectral features originate from the collective molecules of low frequency vibration, rotation and weak interaction with the surrounding molecules （hydrogen bonding, van der Waals force, etc.）, so they are very sensitive to the molecular structure and surrounding environment. It is a powerful tool to investigate molecular conformation, positional isomerism of functional groups, intermolecular interactions of organic acids and their salts, optical isomerism, etc. However, it is worth noting that the investigated targets are usually in the form of multi-component mixtures in actual scenario. When the spectral features became more complicated, the much broader THz features would be severely overlapped and accompanied by baseline drift in THz spectra. Identification and quantitative analysis of complex multi-component mixtures will become a great challenge for THz spectral analysis. To overcome such problem, a practical strategy has been proposed by combining machine learning methods with THz-TDS for implementation of practical applications. Moreover, another issue worth noting is conventional free-standing spectroscopy measurement devices are hardly adequate for the detection of microgram level or trace substance. Combination of metamaterials and conventional free-standing THz spectroscopy to enhance the sensing signal is a feasible and effective method, which is crucial for the practicability of clinical adoption. Furthermore, some recent progress we have achieved in THz characteristic spectral technology and its applications are also summarized and discussed. 相似文献