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1.
2.
B. Pantchev P. Danesh K. Antonova B. Schmidt D. Grambole J. Baran 《Journal of Materials Science: Materials in Electronics》2003,14(10-12):751-752
The hydrogen content, its depth distribution, and its bonding configuration have been studied in hydrogenated amorphous silicon prepared by plasma-enhanced chemical vapor deposition with hydrogen-diluted silane. Nuclear reaction analysis and infrared spectroscopy were used to determine the total amount of hydrogen and its bonded component, respectively. It has been established that the total concentration of hydrogen does not depend on the film thickness, and has a uniform depth profile. The concentration of bonded hydrogen changes with the film thickness within the measurement accuracy. The data obtained suggest the presence of molecular (non-bonded) hydrogen, uniformly distributed in concentration across the film thickness. 相似文献
3.
Fractal Characteristics of Fracture Surfaces 总被引:2,自引:0,他引:2
George R. Baran Claude Roques-Carmes Dohloul Wehbi Michel Degrange 《Journal of the American Ceramic Society》1992,75(10):2687-2691
Quantitative fractography is often used to study material failure mechanisms. During calculation of surface or profile roughness parameters, the magnification used in obtaining fractographic data is found to influence the value of the parameters. Fractal geometry has been developed into a tool capable of defining surface and profile topography without sensitivity to magnification, and several studies have related fractal dimension ( D F ) to other physical or mechanical properties. In this study, we obtained the fractal dimension of profiled fracture surfaces of one glass and three proprietary dental porcelains. The fracture toughness ( K 1c ) of these materials was also measured using the indentation-strength method. Results show the surfaces to be fractal. No quantitative relationship between fractal dimension and toughness was found. Differences in K 1c were demonstrated between some materials. It is postulated that the size range within which fractal dimension can be defined as constant is dependent on the toughening mechanism, and that the relationship between K Ic and D F cannot be identical for all materials. 相似文献
4.
Lucjan Janowski Piotr Kozłowski Remigiusz Baran Piotr Romaniak Andrzej Glowacz Tomasz Rusc 《Multimedia Tools and Applications》2014,68(1):23-40
Video transmission and analysis is often utilized in applications outside of the entertainment sector, and generally speaking this class of video is used to perform specific tasks. Examples of these applications include security and public safety. The Quality of Experience (QoE) concept for video content used for entertainment differs significantly from the QoE of surveillance video used for recognition tasks. This is because, in the latter case, the subjective satisfaction of the user depends on achieving a given functionality. Recognizing the growing importance of video in delivering a range of public safety services, we focused on developing critical quality thresholds in license plate recognition tasks based on videos streamed in constrained networking conditions. Since the number of surveillance cameras is still growing it is obvious that automatic systems will be used to do the tasks. Therefore, the presented research includes also analysis of automatic recognition algorithms. 相似文献
5.
Two classes of nanocomposites were synthesized using an unsaturated polyester resin as the matrix and sodium montmorillonite as well as an organically modified montmorillonite as the reinforcing agents. X‐ray diffraction pattern of the composites showed that the interlayer spacing of the modified montmorillonite expanded from 1.25 nm to 4.5 nm, indicating intercalation. Glass transition values of these composites increased from 72°C, in the unfilled unsaturated polyester, to 86°C in the composite with 10% organically modified montmorillonite. From Scanning Electron Microscopy, it is seen that the degree of intercalation/exfoliation of the modified montmorillonite is higher than in the unmodified one. The mechanical properties also supported these findings, since in general, the tensile modulus, tensile strength, flexural modulus, flexural strength and impact strength of the composites with modified montmorillonite were higher than the corresponding properties of the composites with unmodified montmorillonite. The tensile modulus, tensile strength, flexural modulus and flexural strength values showed a maximum, whereas the impact strength exhibited a minimum at approximately 3–5 wt% modified montmorillonite content. These results imply that the level of exfoliation may also exhibit a maximum with respect to the modified montmorillonite content. The level of improvement in the mechanical properties was substantial. Adding only 3 wt% organically modified clay improved the flexural modulus of unsaturated polyester by 35%. The tensile modulus of unsaturated polyester was also improved by 17% at 5 wt% of organically modified clay loading. 相似文献
6.
Transform coding methods play a very important role in the development of diverse multimedia technologies. The discrete cosine and wavelet transforms are frequently used in the field of image processing and set up a basis for contemporary image compression standards (JPEG, MPEG). In this paper a novel two-channel piecewise-linear subband coding scheme (PL-SBC) is introduced. Its most important advantage are exceptionally fast and easy for implementation computational algorithms combined with good reconstruction quality. The proposed PL-SBC system is based on the dual filter bank consisting of a single filter at the decomposition stage and a single one at the reconstruction stage. For the presented PL-SBC scheme, the conditions of perfect reconstruction and the piecewise-linear approximation filter bank have been defined. The compression properties of a new subband coding scheme have been analysed for different categories of images and in comparison with well-known signal transforms, such as cosine, piecewise-linear, piecewise-constant and wavelet transforms. The research includes a comparison of the reconstruction error both in objective as well as subjective approach. 相似文献
7.
We consider the problem of approximately integrating a Lipschitz function f (with a known Lipschitz constant) over an interval. The goal is to achieve an additive error of at most ε using as few samples of f as possible. We use the adaptive framework: on all problem instances an adaptive algorithm should perform almost as well
as the best possible algorithm tuned for the particular problem instance. We distinguish between
and
, the performances of the best possible deterministic and randomized algorithms, respectively. We give a deterministic algorithm
that uses
samples and show that an asymptotically better algorithm is impossible. However, any deterministic algorithm requires
samples on some problem instance. By combining a deterministic adaptive algorithm and Monte Carlo sampling with variance reduction,
we give an algorithm that uses at most
samples. We also show that any algorithm requires
samples in expectation on some problem instance (f,ε), which proves that our algorithm is optimal. 相似文献
8.
We obtain subquadratic algorithms for 3SUM on integers and rationals in several models. On a standard word RAM with w-bit words, we obtain a running time of
. In the circuit RAM with one nonstandard AC
0 operation, we obtain
. In external memory, we achieve O(n
2/(MB)), even under the standard assumption of data indivisibility. Cache-obliviously, we obtain a running time of
. In all cases, our speedup is almost quadratic in the “parallelism” the model can afford, which may be the best possible.
Our algorithms are Las Vegas randomized; time bounds hold in expectation, and in most cases, with high probability. 相似文献
9.
Z. V. Djordjevic X. Feng Li Won Soo Shin S. L. Wunder G. R. Baran 《Journal of Materials Science》1995,30(11):2968-2980
The branching patterns formed as a result of crack growth in dimethacrylate resins below their glass transition temperatures looked similar to fractal trees. The skeletons of the patterns were analysed numerically for their topological and geometrical properties. The number of branches, N
i
, mean branch lengths, N
i
, and branch angles of a particular order, defined according to the Strahler and inverted Weibel schemes, followed exponential scaling behaviour: N
i
(R
b
)–i
and L
i
(R
l
)
i
. Using the relationship for the fractal dimension D=In R
B
/In R
L
, a value of D=1.4 was obtained for the fracture pattern. Fractal behaviour was also examined by the box-counting method which indicated a power-law dependence of the mass on the box size with fractal dimension exponent D=1.4 in the case of the fracture pattern. However, the mass-shell method for both the fracture pattern and the fractal trees gave an exponential increase of mass with distance from the origin, rather than the power-law behaviour expected for fractals. This was attributed to the fact that branches of different sizes were distributed in restricted regions of space closer to the periphery, rather than uniformly over the whole pattern. 相似文献
10.
Anwar Syed Muhammad Irmakci Ismail Torigian Drew A. Jambawalikar Sachin Papadakis Georgios Z. Akgun Can Ellermann Jutta Akcakaya Mehmet Bagci Ulas 《Journal of Signal Processing Systems》2022,94(5):497-510
Journal of Signal Processing Systems - Segmentation of thigh tissues (muscle, fat, inter-muscular adipose tissue (IMAT), bone, and bone marrow) from magnetic resonance imaging (MRI) scans is useful... 相似文献