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311.
We describe and analyze the experimental realization of a speckle interferometry scheme designed for measurement of the value of the shift of the object surface along the surface itself. In contrast to classical speckle interferometric schemes, we use a specially formed two-dimensional pattern of the random binary structure as a speckle structure. The pattern being illuminated by the white light is photographed with the use of a digital camera. Further processing of the information related to the Fourier transformation of the pictures registered and determination of the obtained fringe structure period is carried out in a PC. 相似文献
312.
Pourya Seyfi Amir Heidari Ahmad Khademi Mehrdad Golghand Marjan Gharavi Hamid Ghomi 《等离子体物理论文集》2021,61(3):e202000155
In this paper, the dynamics and flow behaviour of an atmospheric argon plasma jet was studied in the new nozzle structure similar to the surface dielectric barrier discharge (SDBD) using the Schlieren imaging method. The effect of plasma jet driven by repetitive high-voltage microsecond pulses with low-frequency sinusoidal bias was measured qualitatively in a single mirror Schlieren optical system. The enhancement of plasma jet length and cross-section of plasma jet with surface in this condition is due to highly turbulent flow of argon plasma jet in this structure. This study revealed the important role of SDBD structure and modulated electric field on the behaviour of plasma jet in a high diameter nozzle. In practice, this technique allows us to increase the jet length of the nozzle output to 5 cm and under these conditions, the diameter of the plasma jet cross-section is increased to 8 mm, without increasing the electrical power consumption. Eventually, the hydrophilicity of the surface is also measured by the contact angle of a water droplet that decreases from 78° to 8° after surface treatment, implying we were able to reach a super-hydrophilic surface with this plasma jet structure. 相似文献
313.
C. Sánchez-Aké D. Mustri-Trejo T. García-Fernández M. Villagrán-Muniz 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
In this work two colliding laser-induced plasmas (LIP) on Cu and C were studied by means of time resolved emission spectroscopy and fast photography. The experiments were performed using two opposing parallel targets of Cu and C in vacuum, ablated with two synchronized ns lasers. The results showed an increased emission intensity from copper ions Cu II (368.65, 490.97, 493.16, 495.37 and 630.10 nm) and Cu III (374.47 and 379.08 nm) due to the ionization that occurs during collisions of Cu and C species. It was found that the optimum delay between pulses, which yields the maximum emission enhancement of Cu ions, depends on the sampling distance. On the other hand, the emission intensity of C lines, C II (426.70 nm), C III (406.99 and 464.74 nm) and C IV (465.83 nm), decreased and the formation of C2 molecules was observed. A comparison between the temporal evolution of the individual plasmas and their collision performed by combining imaging and the time resolved emission diagnostics, revealed an increase of the electron temperature and electron density and the splitting of the plume into slow and fast components. 相似文献
314.
R. Viskup B. Praher T. Linsmeyer H. Scherndl J.D. Pedarnig J. Heitz 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
Laser induced breakdown spectroscopy (LIBS) is an emerging technique for fast and accurate compositional analysis of many different materials. We present a systematic study of collinear double-pulse LIBS on different technical polymers such as polyamide, polyvinyl chloride, polyethylene etc. Polymer samples were ablated in air by single-pulse and double-pulse Nd:YAG laser radiation (8 ns pulse duration) and spectra were recorded with an Echelle spectrometer equipped with an ICCD camera. We investigated the evolution of atomic and ionic line emission intensities for different delay times between the laser pulses (from 20 ns to 500 μs) at a laser wavelength of 532 nm. We observed double-pulse LIBS signals that were enhanced as compared to single-pulse measurements depending on the delay time and the type of polymer material investigated. LIBS signals of polymer materials that are enhanced by double-pulse excitation may be useful for monitoring the concentration of heavy metals in polymer materials. 相似文献
315.
《Analytical letters》2012,45(13):2181-2194
Abstract Instigated by developing a flow injection procedure for assay of nitrosyl in concentrated sulphuric acid, different approaches for reliable and robust on-line dilution in FIA were evaluated. These comprised the application of mixing tees in conjunction with mixing coils (including knotted reactors) of different internal diameter, zone sampling, the use of a mixing chamber, micro-sampling, and sample injection by means of pseudo-hydrodynamic injection. The individual approaches are described in detail, their advantages and disadvantages being emphasized in regard to their practical applicability. For each approach the criteria stipulated were that the procedure should allow a dilution factor of approximately 100, yet without excessive zone spreading, so that it, on one hand, could effectively eliminate the pronounced Schlieren effect encountered when mixing concentrated sulphuric acid with an aqueous diluent, and, on the other hand, would permit the sample material to be appropriately conditioned for the ensuing chemical derivatization procedure. It was found that this most reliably could be effected by a combination of pseudo-hydrodynamic injection comprising a mixing point and the use of mixing tees in conjunction with knotted reactors of relatively large internal diameter (1.5 mm). The optimized FI-manifold was used with the Griess method for the spectrophotometric assay of nitrosyl (nitrite) in standards prepared in the matrix of concentrated sulphuric acid (detection limit 0.16 mg/1 NO+-N (3[sgrave])) and in practical WSA-samples. 相似文献
316.
介绍了一种无海面控制点的立体摄影海浪测量方法, 给出了其数学模型和相关算法. 文中利用海浪特性, 基于最小二乘法和海浪波面理论, 给出了一种新的外方位元素定标方式. 与传统的立体摄影定标方式相比, 该定标方式充分利用了平均海平面的性质, 既避免了海面控制点的需求, 又使测量数据更为直观, 同时还为基于运动平台的立体摄影海浪测量技术的发展提供了理论依据. 实验室实验表明基于本文发展的立体摄影测量系统精度较高, 可以用于海面微尺度波的测量; 现场实验表明基于本文发展的立体摄影测量系统测量面积可达104 m2 量级, 是一种有效的大尺度海浪测量手段. 相似文献
317.
Reconstruction of the density field using the Colored Background Oriented Schlieren Technique (CBOS)
In this paper the improved Background Oriented Schlieren technique called CBOS (Colored Background Oriented Schlieren) is described and used to reconstruct density fields of three-dimensional flows. The Background Oriented Schlieren technique (BOS) allows to measure the light deflection caused by density gradients in a compressible flow. For this purpose the local image displacements of the image of a background pattern observed through the flow is used. In order to increase the performance of the conventional Background Oriented Schlieren technique, the monochromatic background is replaced by a colored dot pattern. The different colors are treated separately using suitable correlation algorithms. Therefore, the accuracy and the spatial resolution can be increased. A tomographic reconstruction method is then used to reconstruct the density field in three-dimensional flows from CBOS measurements. 相似文献
318.
319.
Christian C. Van de Sande 《Angewandte Chemie (International ed. in English)》1983,22(3):191-209
Dye diffusion instant color photography has been a commercial success ever since its introduction in 1963. No doubt this is partly due to the spectacular nature of this innovation, and for the same reason it has never really rid itself of its gadget image. Moreover, the picture quality was inferior to that of traditional color photography. Photographic materials are now available whose image quality approaches that of the traditional color print. It is not well known that chemistry, and organic chemistry in particular, is the cornerstone of these new photographic products. Insights from this field have spurred creativity, not only in the fields of dye and polymer chemistry, but above all in the search for more efficient and, hopefully better, dye diffusion transfer systems. The result of all these efforts is a finely tuned microscale chemical factory which continues to open rewarding perspectives for the photographic industry. 相似文献
320.