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排序方式: 共有1057条查询结果,搜索用时 31 毫秒
31.
Snehlata Shakya Anupam Saxena Prabhat Munshi 《Research in Nondestructive Evaluation》2018,29(2):78-94
Two adaptive discretization frameworks are tested for computerized tomography (CT) data reconstruction. Removal of inactive pixels is primary motivation. Efficient and user independent entropy optimized masking is employed for spatial filtering purposes. Density of nodes at high gradient of reconstructed physical property is used as adaptation criterion. An alternative option, independent from noisy projection data and nature of the physical properties, is also discussed. Sensitivity analysis between the uniform and nonuniform (evolved via adaptive route) reconstruction grid reveals the utility of nonuniform grids. Iterative and transform based reconstruction techniques are used. Outcomes are tested successfully on three real world projection data from two different compact CT setups and one commercial high-resolution micro-CT scanner. 相似文献
32.
Swanand J. Deodhar K.B.C. Saxena Rajen K. Gupta Mikko Ruohonen 《The Journal of Strategic Information Systems》2012,21(4):274-294
The open source approach to software development has been used by software organizations in tandem with their existing business models, which are based on proprietary software licensing. This led to the creation of hybrid business models that merge open source and proprietary paradigms. This paper explores the practices used by software product vendors using hybrid business models and proposes strategies emerging out of these practices using interpretive, single case study research design. 相似文献
33.
Saxena Ashutosh Sun Min Ng Andrew Y. 《IEEE transactions on pattern analysis and machine intelligence》2009,31(5):824-840
We consider the problem of estimating detailed 3D structure from a single still image of an unstructured environment. Our goal is to create 3D models that are both quantitatively accurate as well as visually pleasing. For each small homogeneous patch in the image, we use a Markov Random Field (MRF) to infer a set of "plane parameters” that capture both the 3D location and 3D orientation of the patch. The MRF, trained via supervised learning, models both image depth cues as well as the relationships between different parts of the image. Other than assuming that the environment is made up of a number of small planes, our model makes no explicit assumptions about the structure of the scene; this enables the algorithm to capture much more detailed 3D structure than does prior art and also give a much richer experience in the 3D flythroughs created using image-based rendering, even for scenes with significant nonvertical structure. Using this approach, we have created qualitatively correct 3D models for 64.9 percent of 588 images downloaded from the Internet. We have also extended our model to produce large-scale 3D models from a few images. 相似文献
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Zirconium oxide (ZrO2) nanostructures were synthesized by hydrothermal route. Surface morphology analysis depicts the formation of the nanobars and hexagonal-shaped nanodiscs at different synthesis conditions. The structural analysis confirms that the as-synthesized ZrO2 product is of pure monoclinic phase (m-ZrO2) with crystallite size of about 25 nm. The product consists of monodispersed nanoparticles of uniform composition, high purity, and crystallinity. The Raman spectra are quantitatively analyzed and the observed peaks are attributed to various vibration modes of the m-ZrO2. The UV–vis absorption spectrum showed a strong absorption peak at about 292 nm and the estimated optical band gap was around 3.57 eV. Photoluminescence (PL) spectrum of ZrO2 nanostructure showed a strong and broad emission peak at around 410 nm at room temperature, which can be attributed to the ionized oxygen vacancy in the material. 相似文献
36.
Nagabhatla Viswanadham Sandeep K. Saxena M.O. Garg 《Journal of Industrial and Engineering Chemistry》2013,19(3):950-955
An Indian industrial naphtha containing mixture of various hydrocarbons belong to n-paraffins, isoparaffins, naphthenes and aromatics falling in C5 to C9 carbon range has been studied for its octane boosting through the production of isoparaffins over various Pt loaded zeolite catalysts possessing different acidity and porosity properties. Optimum balance of acid and metal functionalities in 0.6 wt.% Pt loaded on BEA zeolite helped in achieving highest increase in research octane number (RON) from 44 to 80, suitable for gasoline applications, through the production of lower isoparaffins (iC4-iC6) along with C7+ isoparaffins. 相似文献
37.
Lyci George Vadym DrozdAndriy Durygin Jiuhua ChenSurendra K. Saxena 《International Journal of Hydrogen Energy》2009
Mg2FeH6 was synthesized by ball milling MgH2 and Fe (2:1 molar ratio) mixture for 72 h followed by heating at 400 °C under H2 pressure. The hydride formation, its structure and homogeneity were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Raman spectroscopy. High pressure in situ synchrotron X-ray diffraction and Vienna ab initio simulation were used to determine bulk modulus of the sample. The bulk modulus of Mg2FeH6 was found to be 75.4(4) GPa by optimized experiment and 76.3 GPa by theoretical simulation. From high temperature in situ X-ray diffraction study the volumetric thermal expansion coefficient of Mg2FeH6 was found to be αv = 5.85(3) × 10−5 + 7.47(7) × 10−8 (T − To)/°C. Decomposition of Mg2FeH6 was observed at 425 °C and the decomposition products were Mg, Fe and H2. 相似文献
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40.
Use of the nanoindentation technique for studying microstructure/crack interactions in the fatigue of 4340 steel 总被引:2,自引:0,他引:2
Fan Yang Ashok Saxena Laura Riester 《Metallurgical and Materials Transactions A》1998,29(12):3029-3036
The objectives of this research are to study the influence of microstructure on the fatigue crack growth behavior in 4340
steel and to explore the application of the nanoindentation technique for determining the plastic deformation zone at a fatigue
crack tip. Two heat treatment conditions were chosen for the steel: annealed and quenched plus tempered. The annealed steel
consists of coarse pearlite and proeutectoid ferrite, while the quenched and tempered steel consists of fine tempered martensite.
Fatigue crack propagation tests were conducted on disklike compact (DCT) specimens. Subsequently, the nanoindentation technique
was applied to quantitatively determine the plastic deformation zone at fatigue crack tips. The plastic deformation zone size
determined by the nanoindentation test seems larger than the cyclic deformation zone calculated using the fracture mechanics
equation, which involves many assumptions. The fatigue crack growth test results show that the annealed steel has a higher
resistance to crack growth than the quenched and tempered steel. The fatigue crack in the annealed steel tends to grow along
pearlite domain boundaries, or the cementite/ferrite interfaces within a pearlite domain. In contrast, the fatigue crack in
the quenched and tempered steel tends to traverse the fine martensite laths. Consequently, the actual crack path in the annealed
steel is rougher than in the quenched and tempered steel and more secondary cracks are observed in the annealed steel. 相似文献