358 resultados para Aggregates , Friction , Image edge detection , Measurement by laser beam , Roads , Surface resistance , Surface texture
Resumo:
Video-based facial expression recognition is a challenging problem in computer vision and human-computer interaction. To target this problem, texture features have been extracted and widely used, because they can capture image intensity changes raised by skin deformation. However, existing texture features encounter problems with albedo and lighting variations. To solve both problems, we propose a new texture feature called image ratio features. Compared with previously proposed texture features, e. g., high gradient component features, image ratio features are more robust to albedo and lighting variations. In addition, to further improve facial expression recognition accuracy based on image ratio features, we combine image ratio features with facial animation parameters (FAPs), which describe the geometric motions of facial feature points. The performance evaluation is based on the Carnegie Mellon University Cohn-Kanade database, our own database, and the Japanese Female Facial Expression database. Experimental results show that the proposed image ratio feature is more robust to albedo and lighting variations, and the combination of image ratio features and FAPs outperforms each feature alone. In addition, we study asymmetric facial expressions based on our own facial expression database and demonstrate the superior performance of our combined expression recognition system.
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Plasma-sprayed 8YSZ (zirconia stabilized with 8 wt% yttria)/NiCoCrAlYTa thermal barrier coatings (TBCs) were laser-glazed using a continuous-wave CO2 laser. Open pores within the coating surface were eliminated and an external densified layer was generated by laser-glazing. The hot corrosion resistances of the plasma-sprayed and laser-glazed coatings were investigated. The two specimens were exposed for the same period of 100 h at 900 degrees C to a salt mixture of vanadium pentoxide (V2O5) and sodium sulfate (Na2SO4). Serious crack and spallation occurred in the as-sprayed coating, while the as-glazed coating exhibited good hot corrosion behavior and consequently achieved a prolonged lifetime. The results showed that the as-sprayed 8YSZ coating achieved remarkably improved hot corrosion resistance by laser-glazing.
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Two significant G-quadruplex aptamers named AGRO100 and T30695 are identified as multi functional aptamers that can bind the protein ligands nucleolin or HIV-1 integrase and hemin. Besides their strong binding to target proteins, both AGRO100 and T30695 exhibit high hemin-binding affinities comparable to that of the known aptamer (termed PS2M) selected by the in vitro evolution process. Most importantly, their corresponding hemin-DNA complexes reveal excellent peroxidase-like activities. higher than that of the reported hemin-PS2M DNAzyme. This enables these multifunctional aptamers to be applied to the sensitive detection of proteins. which is demonstrated by applying AGRO100 to the chemiluminescence detection of nucleolin expressed at the surface of HeLa cells. Based on the specific AGRO100-nucleolin interaction, the surface-expressed nucleolin of HeLa cells is labeled in situ with the hemin-AGRO100 DNAzyme, and then determined in the luminol-H2O2 system.
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Single-walled carbon nanotubes (SWNTs) can selectively induce human telomeric i-motif DNA formation at pH 7.0. Based on this property, we design a DNA nanomachine induced by SWNTs on gold surface. The motor DNA is human telomeric G-quadruplex DNA. The reversible hybridization between the motor DNA and its complementary human telomeric i-motif DNA can be modulated by SWNTs without changing solution pH. Up to now, to our knowledge, there is no report to show that a DNA nanomachine is induced by SWNTs or a DNA nanomachine can detect i-motif formation at pH 7.0. Our work may provide a new concept for designing an SWNT-induced DNA nanomachine and for the detection of i-motif DNA structure at pH 7.0. DNA hybridization, conformational transition and i-motif formation have been characterized on surface or in solution by fluorescence confocal microscopy, circular dichroism, DNA melting and gel electrophoresis. The folding and unfolding kinetics of the DNA nanomachine on gold surface were studied by Fourier transform-surface plasmon resonance (FT-SPR). All these results indicate that SWNTs can induce the DNA nanomachine to work efficiently and reversibly.
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Herein, we report an approach for protein detection enhanced by ionic liquid (IL) selectors in capillary electrophoresis (CE), with avidin as a model protein. Hydrophilic ILs were added into the running buffer of CE and acted as selectors for sample injection, enriching the positive target and excluding the negative from the capillary. When using 3% (v/v) IL selector, the detection sensitivity of avidin was improved by over one order of magnitude, while the interference from protein adsorption was effectively avoided, even in an uncoated capillary. The electrochemiluminescence method was initially used for IL-based CE with low noise that was independent of the IL concentration, making ILs almost transparent as additives in the electrophoresis buffer.
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This paper describes a simple approach to fabricate aggregates composed of monodispersed silica microspheres by modified micromolding in capillaries (MIMIC). Two different kinds of contact modes, namely, conformal contact and non-conformal contact, between the poly(dimethylsiloxane) (PDMS) mold and the underlying prepatterned substrate, can be controlled during the micromolding, which result in the formation of different aggregates under the influence of template confinement and capillary forces. These aggregates, including woodpile structure, discoid, conoid and rectangular clusters, possess well-controlled sizes and orientation. The possible mechanisms for the formation of different aggregates are discussed in detail.
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A FeNiSiBV amorphous composite coating was developed by laser cladding of metallic powders on AISI 1020 low carbon steel substrate. The coatings were studied using X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The coating reveals different microstructures along the depth of the coating. The transition zone exhibits good metallurgical bonding between the substrate and the coating. The layer consists of amorphous phase in majority and nanocrystalline phase/crystalline phase in minority. Accompanied with the nanocrystalline phase, the amorphous phase is concentrated in the middle of the coating. The crystalline phase in the coating is identified as Fe2B. A gradient distribution of the microhardness ranges from 1208 HV0.2 to 891 HV0.2 in the coating along the depth. The coating shows higher microhardness and better wear property than the substrate.
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Attaining sufficient accuracy and efficiency of generalized screen propagator and improving the quality of input gathers are often problemsof wave equation presack depth migration,in this paper,a high order formula of generalized screen propagatorfor one-way wave equation is proposed by using the asymptotic expansion of single-square-root operator. Based on the formulaa new generalized screen propagator is developed ,which is composed of split-step Fourier propagator and high order correction termsthe new generalized screen propagator not only improving calculation precision without sharply increasing the quantity of computationfacilitates the suitability of generalized screen propagator to the media with strong lateral velocity variation.As wave-equation prestack depth migration is sensitive to the quality of input gathers, which greatly affect the outputand the available seismic data processing system has inability to obtain traveltimes corresponding to the multiple arrivals, to estimate of great residual statics to merge seismic datum from different projects and to design inverse Q filter, we establishdifference equations with an embodiment of Huygenss principle for obtaining traveltimes corresponding to the multiple arrivals,bring forward a time variable matching filter for seismic datum merging by using the fast algorithm called Mallat tree for wavelet transformations put forward a method for estimation of residual statics by applying the optimum model parameters estimated by iterative inversion with three organized algorithm,i.e,the CMP intertrace cross-correlation algorithm,the Laplacian image edge extraction algorithm,and the DFP algorithm, and present phase-shift inverse Q filter based on Futtermans amplitude and phase-velocity dispersion formula and wave field extrapolation theory. All of their numerical and real data calculating results shows that our theory and method are practical and efficient. Key words: prestack depth migration, generalized screen propagator, residual staticsinverse Q filter ,traveltime3D seismic datum mergence
Resumo:
This paper studies how to more effectively invert seismic data and predict reservoir under complicated sedimentary environment, complex rock physical relationships and fewer drills in offshore areas of China. Based on rock physical and seismic amplitude-preserving process, and according to depositional system and laws of hydrocarbon reservoir, in the light of feature of seismic inversion methods present applied, series methods were studied. A joint inversion technology for complex geological condition had been presented, at the same time the process and method system for reservoir prediction had been established. This method consists four key parts. 1)We presented the new conception called generalized wave impedance, established corresponding inversion process, and provided technical means for joint inversion lithology and petrophysical on complex geological condition. 2)At the aspect of high-resolution nonlinear seismic wave impedance joint inversion, this method used a multistage nonlinear seismic convolution model rather than conventional primary structure Robinson seismic convolution model, and used Caianiello neural network implement inversion. Based on the definition of multistage positive and negative wavelet, it adopted both deterministic and statistical physical mechanism, direct inversion and indirect inversion. It integrated geological knowledge, rock physical theory, well data, and seismic data, and improved the resolution and anti-noise ability of wave impedence inversion. 3)At the aspect of high-resolution nonlinear reservoir physical property joint inversion, this method used nonlinear rock physical model which introduced convolution model into the relationship between wave impedance and porosity/clay. Through multistage decomposition, it handles separately the large- and small-scale components of the impedance-porosity/clay relationships to achieve more accurate rock physical relationships. By means of bidirectional edge detection with wavelets, it uses the Caianiello neural network to finish statistical inversion with combined applications of model-based and deconvolution-based methods. The resulted joint inversion scheme can integrate seismic data, well data, rock physical theory, and geological knowledge for estimation of high-resolution petrophysical parameters. 4)At the aspect of risk assessment of lateral reservoir prediction, this method integrated the seismic lithology identification, petrophysical prediction, multi-scale decomposition of petrophysical parameters, P- and H-spectra, and the match relationship of data got from seismics, well logging and geology. It could describe the complexity of medium preferably. Through applications of the joint inversion of seismic data for lithologic and petrophysical parameters in several selected target areas, the resulted high-resolution lithologic and petrophysical sections(impedance, porosity, clay) show that the joint inversion can significantly improve the spatial description of reservoirs in data sets involving complex deposits. It proved the validity and practicality of this method adequately.
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In the prediction of complex reservoir with high heterogeneities in lithologic and petrophysical properties, because of inexact data (e.g., information-overlapping, information-incomplete, and noise-contaminated) and ambiguous physical relationship, inversion results suffer from non-uniqueness, instability and uncertainty. Thus, the reservoir prediction technologies based on the linear assumptions are unsuited for these complex areas. Based on the limitations of conventional technologies, the thesis conducts a series of researches on various kernel problems such as inversions from band-limited seismic data, inversion resolution, inversion stability, and ambiguous physical relationship. The thesis combines deterministic, statistical and nonlinear theories of geophysics, and integrates geological information, rock physics, well data and seismic data to predict lithologic and petrophysical parameters. The joint inversion technology is suited for the areas with complex depositional environment and complex rock-physical relationship. Combining nonlinear multistage Robinson seismic convolution model with unconventional Caianiello neural network, the thesis implements the unification of the deterministic and statistical inversion. Through Robinson seismic convolution model and nonlinear self-affine transform, the deterministic inversion is implemented by establishing a deterministic relationship between seismic impedance and seismic responses. So, this can ensure inversion reliability. Furthermore, through multistage seismic wavelet (MSW)/seismic inverse wavelet (MSIW) and Caianiello neural network, the statistical inversion is implemented by establishing a statistical relationship between seismic impedance and seismic responses. Thus, this can ensure the anti-noise ability. In this thesis, direct and indirect inversion modes are alternately used to estimate and revise the impedance value. Direct inversion result is used as the initial value of indirect inversion and finally high-resolution impedance profile is achieved by indirect inversion. This largely enhances inversion precision. In the thesis, a nonlinear rock physics convolution model is adopted to establish a relationship between impedance and porosity/clay-content. Through multistage decomposition and bidirectional edge wavelet detection, it can depict more complex rock physical relationship. Moreover, it uses the Caianiello neural network to implement the combination of deterministic inversion, statistical inversion and nonlinear theory. Last, by combined applications of direct inversion based on vertical edge detection wavelet and indirect inversion based on lateral edge detection wavelet, it implements the integrative application of geological information, well data and seismic impedance for estimation of high-resolution petrophysical parameters (porosity/clay-content). These inversion results can be used to reservoir prediction and characterization. Multi-well constrains and separate-frequency inversion modes are adopted in the thesis. The analyses of these sections of lithologic and petrophysical properties show that the low-frequency sections reflect the macro structure of the strata, while the middle/high-frequency sections reflect the detailed structure of the strata. Therefore, the high-resolution sections can be used to recognize the boundary of sand body and to predict the hydrocarbon zones.
Resumo:
In exploration seismology, the geologic target of oil and gas reservoir in complex medium request the high accuracy image of the structure and lithology of the medium. So the study of the prestack image and the elastic inversion of seismic wave in the complex medium come to the leading edge. The seismic response measured at the surface carries two fundamental pieces of information: the propagation effects of the medium and the reflections from the different layer boundaries in the medium. The propagation represent the low-wavenumber component of the medium, it is so-called the trend or macro layering, whereas the reflections represent the high-wavenumber component of the medium, it is called the detailed or fine layering. The result of migration velocity analysis is the resolution of the low-wavenumber component of the medium, but the prestack elastic inversion provided the resolution of the high-wavvenumber component the medium. In the dissertation, the two aspects about the migration velocity estimation and the elastic inversion have been studied.Firstly, any migration velocity analysis methods must include two basic elements: the criterion that tell us how to know whether the model parameters are correct and the updating that tell us how to update the model parameters when they are incorrect, which are effected on the properties and efficiency of the velocity estimation method. In the dissertation, a migration velocity analysis method based on the CFP technology has been presented in which the strategy of the top-down layer stripping approach are adapted to avoid the difficult of the selecting reduce .The proposed method has a advantage that the travel time errors obtained from the DTS panel are defined directly in time which is the difference with the method based on common image gather in which the residual curvature measured in depth should be converted to travel time errors.In the proposed migration velocity analysis method, the four aspects have been improved as follow:? The new parameterization of velocity model is provided in which the boundaries of layers are interpolated with the cubic spline of the control location and the velocity with a layer may change along with lateral position but the value is calculated as a segmented linear function of the velocity of the lateral control points. The proposed parameterization is suitable to updating procedure.? The analytical formulas to represent the travel time errors and the model parameters updates in the t-p domain are derived under local lateral homogeneous. The velocity estimations are iteratively computed as parametric inversion. The zero differential time shift in the DTS panel for each layer show the convergence of the velocity estimation.? The method of building initial model using the priori information is provided to improve the efficiency of velocity analysis. In the proposed method, Picking interesting events in the stacked section to define the boundaries of the layers and the results of conventional velocity analysis are used to define the velocity value of the layers? An interactive integrate software environment with the migration velocity analysis and prestack migration is built.The proposed method is firstly used to the synthetic data. The results of velocity estimation show both properties and efficiency of the velocity estimation are very good.The proposed method is also used to the field data which is the marine data set. In this example, the prestack and poststack depth migration of the data are completed using the different velocity models built with different method. The comparison between them shows that the model from the proposed method is better and improves obviously the quality of migration.In terms of the theoretical method of expressing a multi-variable function by products of single-variable functions which is suggested by Song Jian (2001), the separable expression of one-way wave operator has been studied. A optimization approximation with separable expression of the one-way wave operator is presented which easily deal with the lateral change of velocity in space and wave number domain respectively and has good approach accuracy. A new prestack depth migration algorithm based on the optimization approximation separable expression is developed and used to testing the results of velocity estimation.Secondly, according to the theory of the seismic wave reflection and transmission, the change of the amplitude via the incident angle is related to the elasticity of medium in the subsurface two-side. In the conventional inversion with poststack datum, only the information of the reflection operator at the zero incident angles can be used. If the more robust resolutions are requested, the amplitudes of all incident angles should be used.A natural separable expression of the reflection/transmission operator is represented, which is the sum of the products of two group functions. One group function vary with phase space whereas other group function is related to elastic parameters of the medium and geological structure.By employing the natural separable expression of the reflection/transmission operator, the method of seismic wave modeling with the one-way wave equation is developed to model the primary reflected waves, it is adapt to a certain extent heterogeneous media and confirms the accuracy of AVA of the reflections when the incident angle is less than 45'. The computational efficiency of the scheme is greatly high.The natural separable expression of the reflection/transmission operator is also used to construct prestack elastic inversion algorithm. Being different from the AVO analysis and inversion in which the angle gathers formed during the prstack migration are used, the proposed algorithm construct a linear equations during the prestack migration by the separable expression of the reflection/transmission operator. The unknowns of the linear equations are related to the elasticity of the medium, so the resolutions of them provided the elastic information of the medium.The proposed method of inversion is the same as AVO inversion in , the difference between them is only the method processing the amplitude via the incident angle and computational domain.
