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排序方式: 共有866条查询结果,搜索用时 156 毫秒
811.
Mohammad Sadegh Shakeri Zaneta Swiatkowska-Warkocka Oliwia Polit Tatiana Itina Alexey Maximenko Joanna Depciuch Jacek Gurgul Marzena Mitura-Nowak Marcin Perzanowski Andrzej Dziedzic Jarosław Nęcki 《Advanced functional materials》2023,33(43):2304359
Phase formation by pulsed laser irradiation of suspended nanoparticles has recently been introduced as a promising synthesis technique for heterostructures. The main challenge still lingers regarding the exact mechanism of particle formation due to the non-equilibrium kinetic by-products resulting from the localized alternative, fast, high-temperature nature of the process. Here, the authors analyze the bond breaking/formation of copper or copper (II) interfaces with ethanol during the absorption of pulses for Cu-CuO-Cu2O formation applicable as an electrocatalyst in ethanol oxidation fuel cells. This study includes but is not limited to, a comprehensive discussion of the interaction between nano-laser pulses and suspension for practical control of the synthesis process. The observed exponential and logarithmic changes in the content of heterostructures for the CuO-ethanol and Cu-ethanol samples irradiated with different fluences are interpreted as the dominant role of physical and chemical reactions, respectively, during the pulsed laser irradiation of suspensions synthesis. It is also shown that the local interface between dissociated ethanol and the molten sphere is responsible for the oxidative/reductive interactions resulting in the formation of catalytic-augmented Cu3+ by-product, thanks to the reactive bond force field molecular dynamics studies confirmed by ab-initio calculations and experimental observations. 相似文献
812.
Paweł Wajer Edyta Woźniak Wlodek Kofman Marcin Rybicki Stanisław Lewiński 《International journal of remote sensing》2018,39(9):2671-2689
This study uses the ray tracing method to simulate synthetic aperture radar (SAR) images of urban areas. The images are constructed for polarisations: horizontal-horizontal (HH) and vertical-vertical (VV), and different types of buildings, vegetation, and streets. Simulated images of a given area are compared with real SAR images of the same area acquired by the TerraSAR-X satellite. The simulations use the measured backscatter coefficient for HH and VV polarisations and for five different classes of terrain: houses, trees, shrubs, grass, and ground. For multiple reflections, we apply the generalized bistatic Lambertian model. The results show that, despite the limits of the ray tracing method and the approximations involved in modelling three-dimensional objects in the simulated scene, the simulated SAR images correspond well with the actual scene. All features present in the real image are reproduced in the simulated image; in particular, the double reflections of buildings and the surrounding ground appear clearly. However, discrepancies exist, and these are also discussed. 相似文献
813.
Marcin Janaszewski Author Vitae Michel Couprie Author Vitae 《Pattern recognition》2010,43(10):3548-2238
The construction of hole filling (or hole segmentation) method for 3D volumetric images is a new challenging issue in computer science. It needs a geometrical approach since from a topological point of view 3D holes (tunnels) are not well-delimited subsets of three dimensional space. In this paper, the authors propose an original, efficient, flexible algorithm of hole filling for volumetric objects. The algorithm has been tested on artificial objects and very complicated crack propagation tomography images. The qualitative results, quantitative results and features of proposed approach are presented in the paper. According to our knowledge it is the first algorithm of hole filling for volumetric objects. 相似文献
814.
815.
The numerical model of a thermoemission ion source was used for source ionization efficiency calculations. The dependency of ionization efficiency on working parameters like ionizer length and extraction voltage was discussed, and a good agreement with theoretical predictions was achieved. It was shown that increasing the ionizer length does not significantly change the obtained ionization efficiency. Extraction voltages up to a few thousand of volts are sufficient to obtain reasonable efficiency. 相似文献
816.
Cancerous mass detection methods for mammographic images still miss some malignant cases on the one hand, and produce too
many false-positive (FP) detections with respect to the number of true-positive (TP) detections on the other. An attempt has
been described to improve the TP ratio per image and to decrease the number of FP errors in the hierarchical template matching
detector of regions of interest (ROIs) for cancerous masses by eliminating the images of linear structures (LSs) from the
mammograms. The LSs were detected with an accumulation-based line detector. The measure of correctness of the ROIs detection
was discussed and the quality of the detector, represented by free receiver operating characteristics curves, was compared
with the human-eye observations. The result is that the widely used measure of detection correctness seems to underestimate
the detection quality made by a human. Tests were performed on the mammograms from the MIAS database. 相似文献
817.
Alexander Kyrychenko Jerzy Herbich Marcin Izydorzak Michał Gil Jacek Dobkowski Feiyue Wu Randolph P. Thummel Jacek Waluk 《Israel journal of chemistry》1999,39(3-4):309-318
Photoinduced two-proton tautomerization has been studied in two types of chromophores: (i) alcohol complexes of azaaromatic molecules possessing both proton donor and acceptor groups; (ii) constitutional isomers of porphyrin. The reaction path for the intermolecular process may involve solvent reorientation around the excited chromophore. In this case, rapid internal conversion is activated, efficiently competing with proton transfer. Another possibility arises if cyclic, doubly-hydrogen-bonded complexes exist already in the ground state. Excitation of such species leads to a fast tautomerization, which is not stopped even at low temperatures. Excited-state double proton transfer also has been observed in cyclic dimers in the crystal phase. In porphyrin isomers, the rate of the process is a function of the strength of the intramolecular hydrogen bond. Dependence of the phototautomerization rate on temperature and on the nature of the surrounding matrix has also been studied. 相似文献
818.
Janina Molenda Mariusz Ziemnicki Jacek Marzec Wojciech Zając Marcin Molenda Mirosław Bućko 《Journal of power sources》2007
In this work we report the investigation of the structural and the electrical properties of orthorhombic LiMnO2 in a wide temperature range in air and in high purity argon (N5). Also we present a correlation between the electrical and the electrochemical properties of the material upon lithium deintercalation. Moreover, its chemical stability against LiPF6 based liquid electrolyte at elevated temperatures was measured and compared with other cathode materials. 相似文献
819.
Modeling the Motion of Dense Smoke in the Wind Field 总被引:1,自引:0,他引:1
This paper presents a volumetric animation technique for modeling the turbulent motion of very dense and turbulent smoke such as one coming from a steam engine. A new method of the wind field generation is proposed. Gas motion is determined by the integration of two independent vector layers. The first one is a combination of flow primitives and the second is created by stochastically generated turbulence. Special attention is taken of the proper construction of the turbulent layer. For the visualization purposes a simple volume raytracer is applied. Many light sources are taken into account to achieve photorealistic effects. Finally some interesting animations are overviewed. Computation times for a PC Pentium 200 and an SGI O2 workstation are compared to demonstrate the high efficiency of the method. 相似文献
820.
Mechanism for the Role of Silicon on the Transition from Graphite to Cementite Eutectic in Cast Iron
Edward Fra? Marcin Górny Hugo F. Lopez 《Metallurgical and Materials Transactions A》2012,43(11):4204-4218
In this work, an analytical solution is proposed to explain the influence of silicon on the transition from graphite to cementite eutectic in cast iron. It is found that this transition can be related to (1) the graphite nucleation potential (directly characterized by the cell count N and indirectly by the nucleation coefficients N s and b), (2) the growth rate coefficient of graphite eutectic cells ??, (3) the temperature range ??T sc?=?T s ?C T c (where T s and T c are the equilibrium temperature for graphite eutectic and the formation temperature for cementite eutectic, respectively), and (4) the liquid volume fraction f l after preeutectic austenite solidification. Analytical equations were derived that describe the absolute and the relative chilling tendencies (CT and CTr, respectively) as well as the critical cooling rate Q cr and, hence, the chill w of the cast iron. Theoretical arguments are experimentally verified for castings with various silicon contents. This work also describes the methods used in the determination of N s, b, and ?? values. It is found that the main role of silicon on the transition from graphite to cementite eutectic is to raise the density of the graphite nuclei N and temperature range ??T sc. In addition, it is shown that increasing the silicon content of cast iron leads to an increasing value of Q cr and decreasing values of CT and CTr, and of the chill width w. In particular, this work shows that the chilling tendency indexes and, hence, the chill all can be estimated from a simple thermal analysis using reference castings. 相似文献