944 resultados para Space analysis
Resumo:
The accurate recognition of cancer subtypes is very significant in clinic. Especially, the DNA microarray gene expression technology is applied to diagnosing and recognizing cancer types. This paper proposed a method of that recognized cancer subtypes based on geometrical learning. Firstly, the cancer genes expression profiles data was pretreated and selected feature genes by conventional method; then the expression data of feature genes in the training samples was construed each convex hull in the high-dimensional space using training algorithm of geometrical learning, while the independent test set was tested by the recognition algorithm of geometrical learning. The method was applied to the human acute leukemia gene expression data. The accuracy rate reached to 100%. The experiments have proved its efficiency and feasibility.
Resumo:
With a view to solve the problems in modern information science, we put forward a new subject named High-Dimensional Space Geometrical Informatics (HDSGI). It builds a bridge between information science and point distribution analysis in high-dimensional space. A good many experimental results certified the correctness and availability of the theory of HDSGI. The proposed method for image restoration is an instance of its application in signal processing. Using an iterative "further blurring-debluring-further blurring" algorithm, the deblured image could be obtained.
Resumo:
Microtwins in the 3C-SiC films grown on Si(0 0 1) by atmosphere pressure chemical vapor deposition (APCVD) were investigated in detail using X-ray four-circle diffractometry. The Phi scan shows that 3C-SiC films can grow on Si substrates epitaxially and epitaxial relationship is revealed as (0 0 1)(3C) (SiC)parallel to (0 0 1)(Si),[1 1 1](3C-SiC)parallel to [1 1 1](Si). Other diffraction peaks at about 15.8 degrees in x emerged in the pole figures of the (I 1 1) 3C-SiC. We performed the pole figure of (1 0 (1) over bar 0)h-SiC and the reciprocal space mapping from the (1 1 1) reciprocal lattice point of base SiC to the (0 0 2) point of microtwin for the first time, indicating that the diffraction peaks at 15.8 degrees in x result from not hexagonal SiC but microtwins of 3C-SiC, and twin inclusions are estimated to be around 1%. (C) 2001 Published by Elsevier Science B.V.
Resumo:
On the basis of integrated intensity of rocking curves, the multiplicity factor and the diffraction geometry factor for single crystal X-ray diffraction (XRD) analysis were proposed and a general formula for calculating the content of mixed phases was obtained. With a multifunction four-circle X-ray double-crystal diffractometer, pole figures of cubic (002), {111} and hexagonal {1010} and reciprocal space mapping were measured to investigate the distributive character of mixed phases and to obtain their multiplicity factors and diffraction geometry factors. The contents of cubic twins and hexagonal inclusions were calculated by the integrated intensities of rocking curves of cubic (002), cubic twin {111}, hexagonal {1010} and {1011}.
Resumo:
With a view to solve the problems in modern information science, we put forward a new subject named High-Dimensional Space Geometrical Informatics (HDSGI). It builds a bridge between information science and point distribution analysis in high-dimensional space. A good many experimental results certified the correctness and availability of the theory of HDSGI. The proposed method for image restoration is an instance of its application in signal processing. Using an iterative "further blurring-debluring-further blurring" algorithm, the deblured image could be obtained.
Resumo:
The output characteristics of micro-solar cell arrays are analyzed on the basis of a modified model in which the shunt resistance between cell lines results in current leakage. The modification mainly consists of adding a shunt resistor network to the traditional model. The obtained results agree well with the reported experimental results. The calculation results demonstrate that leakage current in substrate affects seriously the performance of GaAs micro- solar cell arrays. The performance of arrays can be improved by reducing the number of cells per line. In addition, at a certain level of integration, an appropriate space occupancy rate of the single cell is recommended for ensuring high open circuit voltages, and it is more appropriate to set the rates at 80%-90% through the calculation.
Resumo:
We investigate slow-light pulse propagation in an optical fiber via transient stimulated Brillouin scattering. Space-time evolution of a generating slow-light pulse is numerically calculated by solving three-wave coupled-mode equations between a pump beam, an acoustic wave, and a counterpropagating signal pulse. Our mathematical treatments are applicable to both narrowband and broadband pump cases. We show that the time delay of 85% pulse width can be obtained for a signal pulse of the order of subnanosecond pulse width by using a broadband pump, while the signal pulse is broadened only by 40% of the input signal pulse. The physical origin of the pulse broadening and distortion is explained in terms of the temporal decay of the induced acoustic field. (C) 2009 Optical Society of America
Resumo:
Current-based microscopic defect analysis methods with optical filling techniques, namely current deep level transient spectroscopy (I-DLTS) and thermally stimulated current (TSC), have been used to study defect levels in a high resistivity silicon detector (p(+)-n-n(+)) induced by very high fluence neutron (VHFN) irradiation (1.7x10(15) n/cm(2)). As many as fourteen deep levels have been detected by I-DLTS. Arrhenius plots of the I-DLTS data have shown defects with energy levels ranging from 0.03 eV to 0.5 eV in the energy band gap. Defect concentrations of relatively shallow levels (E(t) < 0.33 eV) are in the order of 10(13)cm(-3), while those for relatively deep levels (E(t) > 0.33 eV) are in the order of 10(14) cm(-3). TSC data have shown similar defect spectra. A full depletion voltage of about 27,000 volts has been estimated by C-V measurements for the as-irradiated detector, which corresponds to an effective space charge density (N-eff) in the order of 2x10(14) cm(-3). Both detector leakage current and full depletion voltage have been observed to increase with elevated temperature annealing (ETA). The increase of the full depletion voltage corresponds to the increase of some deep levels, especially the 0.39 eV level. Results of positron annihilation spectroscopy have shown a decrease of total concentration of vacancy related defects including vacancy clusters with ETA, suggesting the breaking up of vacancy clusters as possible source of vacancies for the formation of single defects during the reverse anneal.
Resumo:
The theoretical analysis and experimental measurement on the angle dependence of quantum efficiency of GaAs based resonant cavity enhanced (RCE) photodetector is presented. By changing the angle of incoming light, about 40mn wavelength variation of peak quantum efficiency has been experimentally obtained. The peak quantum efficiency and optical bandwidth at different mode corresponding to different angle incidence have been characterized with different absorption dependence on wavelength. The convenient angle tuning of resonant mode will be helpful to relax the strict constraint of RCE photodetector to light source with narrow emission spectrum while especially applied in space optical detections and communications.
Resumo:
A thermodynamic model for the GaSb-GaCl3 system in a closed quartz ampoule was proposed. The species in the gas phase are GaCl, GaCl3, Sb-4, Sb-2. The partial pressures of these species and total pressure in the ampoule have been calculated. The calculated results indicate that the equilibrium partial pressures of GaCl, GaCl3, Sb4, Sb2 and the total pressure in the ampoule have strong dependence on temperature, free volume inside the closed ampoule and amount of transport agent GaCl3. The total pressure will give strong influence not only on the flow pattern in the ampoule, but also on the uniformity of the epilayer.
Resumo:
For an orthotropic laminate, an equivalent system with doubly cyclic periodicity is introduced. Then a 3-dimensional finite element model for the equivalent system is transformed into the unitary space, where the large finite element matrix equation is decoupled into some small matrix equations. Such a decoupling very efficiently reduces the computational effort. For an orthotropic laminate with four clamped edges, no exact elasticity solution is available, and the deflection values predicted by different methods have a considerable difference each other for a small length-to-thickness ratio. The present predictions are the largest because the present method is a full 3-dimensional finite element analysis without superfluous constraints. Illustrative numerical examples are presented to observe the distributions of stresses through the thickness of the laminates. (C) 2010 Elsevier Ltd. All rights reserved.
Resumo:
The output characteristics of micro-solar cell arrays are analyzed on the basis of a modified model in which the shunt resistance between cell lines results in current leakage. The modification mainly consists of adding a shunt resistor network to the traditional model. The obtained results agree well with the reported experimental results. The calculation results demonstrate that leakage current in substrate affects seriously the performance of GaAs micro- solar cell arrays. The performance of arrays can be improved by reducing the number of cells per line. In addition, at a certain level of integration, an appropriate space occupancy rate of the single cell is recommended for ensuring high open circuit voltages, and it is more appropriate to set the rates at 80%-90% through the calculation.
Resumo:
Single crystals of PrMnO3 and TbMnO3 were grown by floating zone method and the crystal structure was determined by single crystal X-ray diffractometry. The structure of these compounds belongs to the orthorhombic system (space group is Pnma, No. 62) with the lattice parameters alpha approximate to root (.) - a(p), b approximate to 2 (.) a(p) , c approximate to root 2.a(p) and Z = 4, where a(p) is ideal cubic perovskite cell parameter.
Resumo:
The crystal structure of erbium (III) complex of benzene acetic acid is reported. The complex crystallizes in the monoclinic space group P2(1)/a with a = 0,9008(3)nm, b=1.4242(5) nm, c=1.8437(7) nm, beta=98.80(3)degrees, V = 2.337(1) nm(3), Z = 4. The mechanism of thermal decomposition of complex has been studied by TG-DTG-DTA. The activation energy for dehydration reaction has been calculated by Freeman Carroll method. The enthalpy change for dehydration and phase change process has been determined.
Resumo:
Analysis of accommodation space variation during deposition of the Cretaceous Qingshankou Formation in the Songliao Basin, NE China, indicates that accommodation space changed both through time and across the basin as a seesaw movement. The mid-upper Qingshankou Formation is divided into three units. In each unit, changes of accommodation space differ in the southern and northern part of the basin. Increasing accommodation in the southern part is accompanied by a decrease in the northern part, and vice versa. Between the northern and southern basin, there was a neutral belt that is like a fulcrum, called the transformation belt here, where the accommodation did not change to any significant degree. We call this response 'accommodation transformation', whose characteristics are defined by tectonic subsidence analysis, palaeontological and sedimentary analyses. The accommodation increasing belt, decreasing belt, transformation belt and accommodation transformation boundary together constitute the accommodation transformation system. The recognition of accommodation transformation in the Songliao Basin provides a new insight into sequence stratigraphy and might be widely applicable.