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Information System Construction and Function Module Design Based on Reverse Logistics
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作者 赵佳妮 石丽娜 《Journal of Donghua University(English Edition)》 EI CAS 2015年第2期328-331,共4页
Reverse logistics are playing more and more important role with the development of competition and the social responsibility of enterprises.It could be divided into commission acceptance,recycling and returned goods h... Reverse logistics are playing more and more important role with the development of competition and the social responsibility of enterprises.It could be divided into commission acceptance,recycling and returned goods handling.Reverse logistics information system consists of the database establishment,network structure and logic structure design.The collection,storage,processing,transmission and output functions of the reverse logistics information system were discussed in the thesis.Eventually,it established seven modules for the reverse logistics information system including the system management module,oriented module,returning goods processing module,reverse transportation management module,information sharing module,statistical analysis module and cost control module. 展开更多
关键词 reverse logistics information systems system construction function modules
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Analysis of the optical quality by determining the modulation transfer function for anterior corneal surface in myopes 被引量:6
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作者 Yan-Zhen Zheng, Yao-Yu Li 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2012年第2期196-201,共6页
AIM: To describe the characteristics of modulation transfer function (MTF) of anterior corneal surface, and obtain the the normal reference range of MTF at different spatial frequencies and optical zones of the anteri... AIM: To describe the characteristics of modulation transfer function (MTF) of anterior corneal surface, and obtain the the normal reference range of MTF at different spatial frequencies and optical zones of the anterior corneal surface in myopes. METHODS: Four hundred eyes from 200 patients were examined under SIRIUS corneal topography system. Phoenis analysis software was applied to simulate the MTF curves of anterior corneal surface at vertical and horizontal meridians at the 3, 4, 5, 6, 7mm optical zones of cornea. The MTF values at spatial frequencies of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 cycles/degree (c/d) were selected. RESULTS: The MTF curve of anterior corneal surface decreased rapidly from low to intermediate frequency (0-15cpd) at various optical zones of cornea, the value decreased to 0 slowly at higher frequency (>15cpd). With the increase of the optical zones of cornea, MTF curve decreased gradually. 3) In the range of 3 mm- 6 mm optical zones of the cornea, the MTF values measured at horizontal meridian were greater than the corresponding values at horizontal meridian of each spatial frequency, the difference was statistically significant (P<0.05). At 7 mm optical zones of cornea, the MTF values measured at horizontal meridian were less than the corresponding values at vertical meridian at 10-60 spatial frequencies (cpd), and the difference was statistically significant in 25, 30, 35, 40, 45, 50 cpd(P<0.05). CONCLUSION: MTF can be used to describe the imaging quality of optical systems at anterior corneal surface objectively in detail. 展开更多
关键词 modulation transfer function optical quality CORNEA point spread function optical transfer function phase transfer function
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Modulation transfer function characteristic of uniform-doping transmission-mode GaAs/GaAlAs photocathode 被引量:2
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作者 任玲 常本康 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第8期398-402,共5页
The resolution characteristic can be obtained by the modulation transfer function (MTF) of a GaAs/GaA1As photocathode. After establishing the theoretical model of GaAs(100)-oriented atomic configuration and the fo... The resolution characteristic can be obtained by the modulation transfer function (MTF) of a GaAs/GaA1As photocathode. After establishing the theoretical model of GaAs(100)-oriented atomic configuration and the formula for the ionized impurity scattering of the non-equilibrium carriers, this paper calculates the trajectories of photoelectrons in a photocathode. Thus the distribution of photoelectron spots on the emit-face is obtained, which is namely the point spread function. The MTF is obtained by Fourier transfer of the line spread function obtained from the point spread function. The MTF obtained from these calculations is shown to depend heavily on the electron diffusion length, and enhanced considerably by decreasing the electron diffusion length and increasing the doping concentration. Furthermore, the resolution is enhanced considerably by increasing the active-layer thickness, especially at high spatial frequencies. The best spatial resolution is 860 lp/mm, for the GaAs photocathode of doping concentration 1 ×10^19 cm 3 electron diffusion length 3.6 μm and the active-layer thickness 2 μm, under the 633-nm light irradiated. This research will contribute to the future improvement of the cathode's resolution for preparing a high performance GaAs photocathode, and improve the resolution of a low light level image intensifier. 展开更多
关键词 GaAs/GaAlAs photocathode uniform-doping modulation transfer function spatial res-olution
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Solving the atmospheric scattering optical transfer function using the multi-coupled single scattering method
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作者 孙斌 洪津 孙晓兵 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第9期200-204,共5页
The atmospheric scattering optical transfer function (OTF) is solved by applying the multi-coupled single scattering (MCSS) method to the three-dimensional radiative transfer equation (RTE) under the periodic gr... The atmospheric scattering optical transfer function (OTF) is solved by applying the multi-coupled single scattering (MCSS) method to the three-dimensional radiative transfer equation (RTE) under the periodic ground condition. This approach is a direct hit to the atmospheric scattering OTF using the same original context of modulation transfer function (MTF) measurement, i.e., images of sinusoidal grating at different spatial frequencies. Both the amplitude and phase shift of the OTF at various zenith and azimuth angles can be obtained at an arbitrary spatial frequency. 展开更多
关键词 atmospheric scattering optical transfer function modulation transfer function multi-coupled single scattering method
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Comparison of the retinal modulation transfer function between amblyopes successfully corrected and normal subjects
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作者 Xiao-Ming Huang, Guo-Xing Xu 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2011年第3期284-285,共2页
AIM:To analyze the retinal modulation transfer function between amblyopes whose visual acuity was corrected to 5.0 and normal subjects at the same age. METHODS: RM-800 used to detect contrast sensitivity was adopted t... AIM:To analyze the retinal modulation transfer function between amblyopes whose visual acuity was corrected to 5.0 and normal subjects at the same age. METHODS: RM-800 used to detect contrast sensitivity was adopted to measure MTF of 96 amblyopes (96 eyes) whose visual acuity was corrected to 5.0 and 80 normal controls (80 eyes) at the same age under six interference fringes (IVA=0.06, 0.1, 0.2, 0.4, 0.6, 0.8). RESULTS: The functional values of amblyopes were significantly lower than those of normal subjects in every fringe (P<0.01), especially in medium and high frequency. CONCLUSION: For amblyopes, MTF was still abnormal after stopping the treatments. 展开更多
关键词 modulation transfer function amblyope Interference Fringe Visual Acuity
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Fuzzy image restoration using modulation transfer function
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作者 袁媛 Yi Yaohua Liu Juhua 《High Technology Letters》 EI CAS 2016年第4期461-469,共9页
The key difficulty of restoring a fuzzy image is to estimate its point spread function( PSF). In the paper,PSF is modelled based on modulation transfer function( MTF). The first step is calculating the image MTF. In t... The key difficulty of restoring a fuzzy image is to estimate its point spread function( PSF). In the paper,PSF is modelled based on modulation transfer function( MTF). The first step is calculating the image MTF. In the traditional slanted-edge method,a sub-block is always manually extracted from original image and its MTF will be viewed as the result of the whole image. However,handcraft extraction is inefficient and will lead to inaccurate results. Given this,an automatic MTF computation algorithm is proposed,which extracts and screens out all the effective sub-blocks and calculates their average MTF as the final result. Then,a two-dimensional MTF restoration model is constructed by multiplying the horizontal and vertical MTF,and it is combined with conventional image restoration methods to restore fuzzy image. Experimental results indicate the proposed method implementes a fast and accurate MTF computation and the MTF model improves the performance of conventional restoration methods significantly. 展开更多
关键词 fuzzy image modulation transfer function(MTF) slanted-edge method automatic computation MTF restoration model
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Identification of Risk Pathways and Functional Modules for Coronary Artery Disease Based on Genome-wide SNP Data 被引量:3
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作者 Xiang Zhao Yi-Zhao Luan +8 位作者 Xiaoyu Zuo Ye-Da Chen Jiheng Qin Lv Jin Yiqing Tan Meihua Lin Naizun Zhang Yan Liang Shao-Qi Rao 《Genomics, Proteomics & Bioinformatics》 SCIE CAS CSCD 2016年第6期349-356,共8页
Coronary artery disease (CAD) is a complex human disease, involving multiple genes and their nonlinear interactions, which often act in a modular fashion. Genome-wide single nucleotide polymorphism (SNP) profiling... Coronary artery disease (CAD) is a complex human disease, involving multiple genes and their nonlinear interactions, which often act in a modular fashion. Genome-wide single nucleotide polymorphism (SNP) profiling provides an effective technique to unravel these underlying genetic interplays or their functional involvements for CAD. This study aimed to identify the susceptible pathways and modules for CAD based on SNP omics. First, the Wellcome Trust Case Control Consortium (WTCCC) SNP datasets of CAD and control samples were used to assess the joint effect of multiple genetic variants at the pathway level, using logistic kernel machine regression model. Then, an expanded genetic network was constructed by integrating statistical gene-gene interactions involved in these susceptible pathways with their protein protein interaction (PPI) knowledge. Finally, risk functional modules were identified by decomposition of the network. Of 276 KEGG pathways analyzed, 6 pathways were found to have a significant effect on CAD. Other than glycerolipid metabolism, glycosaminoglycan biosynthesis, and cardiac muscle contraction pathways, three pathways related to other diseases were also revealed, including Alzheimer's disease, non-alcoholic fatty liver disease, and Huntington's disease. A genetic epistatic network of 95 genes was further constructed using the abovementioned integrative approach. Of 10 functional modules derived from the network, 6 have been annotated to phospholipase C activity and cell adhesion molecule binding, which also have known functional involvement in Alzheimer's disease. These findings indicate an overlap of the underlying molecular mechanisms between CAD and Alzheimer's disease, thus providing new insights into the molecular basis for CAD and its molecular relationships with other diseases. 展开更多
关键词 Coronary artery disease Genome-wide SNP profiling Risk pathway functional module Genetic network
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Identification of linear continuous-time system using wavelet modulating filters 被引量:4
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作者 贺尚红 钟掘 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2004年第3期270-277,共8页
An approach to identification of linear continuous-time system is studied with modulating functions. Based on wavelet analysis theory, the multi-resolution modulating functions are designed, and the corresponding filt... An approach to identification of linear continuous-time system is studied with modulating functions. Based on wavelet analysis theory, the multi-resolution modulating functions are designed, and the corresponding filters have been analyzed. Using linear modulating filters, we can obtain an identification model that is parameterized directly in continuous-time model parameters. By applying the results from discrete-time model identification to the obtained identification model, a continuous-time estimation method is developed. Considering the accuracy of parameter estimates, an instrumental variable (Ⅳ) method is proposed, and the design of modulating integral filter is discussed. The relationship between the accuracy of identification and the parameter of modulating filter is investigated, and some points about designing Gaussian wavelet modulating function are outlined. Finally, a simulation study is also included to verify the theoretical results. 展开更多
关键词 parameter estimation modulation function continuous-time system WAVELET Gaussian function.
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Urban niche dynamics of Kaifeng city 被引量:2
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作者 Ding Shengyan1, Li Zhiheng1,2,3 1. College of Environment & Planning, Henan University, Kaifeng 475001, China 2. Xishuangbanna Tropical Botanic Garden, CAS, Kunming 650223, China 3. Graduate School of the Chinese Academy of Sciences, Beijing 100039, China 《Journal of Geographical Sciences》 SCIE CSCD 2007年第2期221-233,共13页
Niche theory is one of the most important ecological theories. It is widely applied to analyzing such phenomena as competition among, and evolution of, urban ecosystem functional modules. This paper describes a study ... Niche theory is one of the most important ecological theories. It is widely applied to analyzing such phenomena as competition among, and evolution of, urban ecosystem functional modules. This paper describes a study concerning'different functional modules of Kaifeng city urban ecosystem. Niche theory and techniques were used to analyze the changes of these functional modules in the period 1994-2003. The results showed that, in the period 1994-2003: (1) Niche value of the atmospheric environment and urban virescence modules increased, while niche value of the water environment and sound environment modules decreased; (2) niche value of the tertiary industry module increased, niche value of the secondary industry module decreased, while niche value of the primary industry module showed little change; and (3) niche value of the infrastructure, resource distribution, and production & social security modules increased, while niche value of the population module decreased. This study may contribute to macroscopic planning of urban functional modules, economic development, and environmental protection. 展开更多
关键词 NICHE PATTERN functional modules DYNAMIC Kaifeng city
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Temporal Characteristics of GaAs NEA and Alkali Metal Photocathodes 被引量:1
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作者 李相民 周立伟 《Journal of Beijing Institute of Technology》 EI CAS 2003年第4期381-384,共4页
The temporal characteristics of GaAs NEA and alkali metal photocathodes are studied using Monte Carlo simulation method. The electron transit time and its distribution functions in the photocathodes are calculated. Ba... The temporal characteristics of GaAs NEA and alkali metal photocathodes are studied using Monte Carlo simulation method. The electron transit time and its distribution functions in the photocathodes are calculated. Based on the results, the time modulation transfer functions and temporal resolutions of the photocathodes are obtained. The results show that the response time and temporal resolution of alkali metal photocathode is in femitosecond order and those of GaAs NEA photocathode are in picosecond order. 展开更多
关键词 GaAs photocathode alkali metal photocathode Monte Carlo simulation time modulation transfer function
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An Improved Coupling of Numerical and Physical Models for Simulating Wave Propagation 被引量:1
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作者 阳志文 柳淑学 李金宣 《China Ocean Engineering》 SCIE EI CSCD 2014年第1期1-16,共16页
An improved coupling of numerical and physical models for simulating 2D wave propagation is developed in this paper. In the proposed model, an unstructured finite element model (FEM) based Boussinesq equations is ap... An improved coupling of numerical and physical models for simulating 2D wave propagation is developed in this paper. In the proposed model, an unstructured finite element model (FEM) based Boussinesq equations is applied for the numerical wave simulation, and a 2D piston-type wavemaker is used for the physical wave generation. An innovative scheme combining fourth-order Lagrange interpolation and Runge-Kutta scheme is described for solving the coupling equation. A Transfer function modulation method is presented to minimize the errors induced from the hydrodynamic invalidity of the coupling model and/or the mechanical capability of the wavemaker in area where nonlinearities or dispersion predominate. The overall performance and applicability of the coupling model has been experimentally validated by accounting for both regular and irregular waves and varying bathymetry. Experimental results show that the proposed numerical scheme and transfer function modulation method are efficient for the data transfer from the numerical model to the physical model up to a deterministic level. 展开更多
关键词 coupling numerical model physical model wave propagation transfer function modulation
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Characterization of a Multimodal and Multispectral Led Imager: Application to Organic Polymer’s Microspheres with Diameter Φ = 10.2 μm 被引量:2
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作者 Marcel A. Agnero Jérémie T. Zoueu Kouakou Konan 《Optics and Photonics Journal》 2016年第7期171-183,共14页
Multispectral microscopy enables information enhancement in the study of specimens because of the large spectral band used in this technique. A low cost multimode multispectral microscope using a camera and a set of q... Multispectral microscopy enables information enhancement in the study of specimens because of the large spectral band used in this technique. A low cost multimode multispectral microscope using a camera and a set of quasi-monochromatic Light Emitting Diodes (LEDs) ranging from ultraviolet to near-infrared wavelengths as illumination sources was constructed. But the use of a large spectral band provided by non-monochromatic sources induces variation of focal plan of the imager due to chromatic aberration which rises up the diffraction effects and blurs the images causing shadow around them. It results in discrepancies between standard spectra and extracted spectra with microscope. So we need to calibrate that instrument to be a standard one. We proceed with two types of images comparison to choose the reference wavelength for image acquisition where diffraction effect is more reduced. At each wavelength chosen as a reference, one image is well contrasted. First, we compare the thirteen well contrasted images to identify that presenting more reduced shadow. In second time, we determine the mean of the shadow size over the images from each set. The correction of the discrepancies required measurements on filters using a standard spectrometer and the microscope in transmission mode and reflection mode. To evaluate the capacity of our device to transmit information in frequency domain, its modulation transfer function is evaluated. Multivariate analysis is used to test its capacity to recognize properties of well-known sample. The wavelength 700 nm was chosen to be the reference for the image acquisition, because at this wavelength the images are well contrasted. The measurement made on the filters suggested correction coefficients in transmission mode and reflection mode. The experimental instrument recognized the microsphere’s properties and led to the extraction of the standard transmittance and reflectance spectra. Therefore, this microscope is used as a conventional instrument. 展开更多
关键词 Multispectral Imaging Reference Wavelength Correction Coefficients Modulation Transfer function
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MDA-TOEPGA:A novel method to identify miRNA-disease association based on two-objective evolutionary programming genetic algorithm
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作者 BUWEN CAO JIAWEI LUO +1 位作者 SAINAN XIAO XIANGJUN ZHOU 《BIOCELL》 SCIE 2022年第8期1925-1933,共9页
The association between miRNA and disease has attracted more and more attention.Until now,existing methods for identifying miRNA related disease mainly rely on top-ranked association model,which may not provide a full... The association between miRNA and disease has attracted more and more attention.Until now,existing methods for identifying miRNA related disease mainly rely on top-ranked association model,which may not provide a full landscape of association between miRNA and disease.Hence there is strong need of new computational method to identify the associations from miRNA group view.In this paper,we proposed a framework,MDA-TOEPGA,to identify miRNAdisease association based on two-objective evolutionary programming genetic algorithm,which identifies latent miRNAdisease associations from the view of functional module.To understand the miRNA functional module in diseases,the case study is presented.We have been compared MDA-TOEPGA with several state-of-the-art functional module algorithm.Experimental results showed that our method cannot only outperform classical algorithms,such as K-means,IK-means,MCODE,HC-PIN,and ClusterONE,but can also achieve an ideal overall performance in terms of a composite score consisting of f1,Sensitivity,and Accuracy.Altogether,our study showed that MDA-TOEPGA is a promising method to investigate miRNA-disease association from the landscapes of functional module. 展开更多
关键词 MiRNA functional module MiRNA-disease association Two-objective Evolutionary programming genetic algorithm
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Animal Hospital Management System Design Based on C/S/S Structure
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作者 HUANG Jing ZHAO Jie WEI Xiaoli 《Journal of Northeast Agricultural University(English Edition)》 CAS 2008年第1期79-82,共4页
By analysis of the functions of animal hospital's departments, combining with management information development truth, the paper developed animal hospital management system. The system included six modules, like sys... By analysis of the functions of animal hospital's departments, combining with management information development truth, the paper developed animal hospital management system. The system included six modules, like system management module basic information management module, sections management module, and so on. The paper used Visual C++6.0 and SQL Server 2000, and ODBC database accessing technology, which can encapsulate any database table and operation into class. The system could make any window to share table's operation to realize hospital management quickly and efficiency. 展开更多
关键词 management system Visual C++6.0 functional modules interface design
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Multi-objective Particle Swarm Optimization Algorithm Based on Performance and Reliability of Discrete System Resources Configuration
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作者 周国财 高翔 《Journal of Donghua University(English Edition)》 EI CAS 2014年第6期850-852,共3页
Considering research on multi-objective optimization for reliability and performance suffering cost constraints in digital circuits,an improved multi-objective optimization algorithm based on performance and reliabili... Considering research on multi-objective optimization for reliability and performance suffering cost constraints in digital circuits,an improved multi-objective optimization algorithm based on performance and reliability was proposed to solve the problem of discrete system resources configuration in this paper. This algorithm used the particle-swarm optimization( PSO) to evaluate the tradeoffs configuration of the system resources between reliability and performance and proved the feasibility through the simulation.Finally, the information of resources configuration from optimization algorithm was used to effectively guide the system design so as to mitigate soft errors caused by single event effect( SEE). 展开更多
关键词 multi-objective optimization function module soft error triple modular redundancy(TMR)
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New modal identification method under the non-stationary Gaussian ambient excitation
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作者 杜秀丽 汪凤泉 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第10期1295-1304,共10页
Based on the multivariate continuous time autoregressive (CAR) model, this paper presents a new time-domain modal identification method of linear time-invariant system driven by the uniformly modulated Gaussian rand... Based on the multivariate continuous time autoregressive (CAR) model, this paper presents a new time-domain modal identification method of linear time-invariant system driven by the uniformly modulated Gaussian random excitation. The method can identify the physical parameters of the system from the response data. First, the structural dynamic equation is transformed into a continuous time autoregressive model (CAR) of order 3. Second, based on the assumption that the uniformly modulated function is approximately equal to a constant matrix in a very short period of time and on the property of the strong solution of the stochastic differential equation, the uniformly modulated function is identified piecewise. Two special situations are discussed. Finally, by virtue of the Girsanov theorem, we introduce a likelihood function, which is just a con- ditional density function. Maximizing the likelihood function gives the exact maximum likelihood estimators of model parameters. Numerical results show that the method has high precision and the computation is efficient. 展开更多
关键词 modal identification uniformly modulated function continuous time autoregressive model Brownian motion exact maximum likelihood estimator
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QUASI-NEUTRAL LIMIT OF THE BIPOLAR NAVIER-STOKES-POISSON SYSTEM
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作者 杨秀绘 《Acta Mathematica Scientia》 SCIE CSCD 2011年第4期1272-1280,共9页
This paper is concerned with the quasi-neutral limit of the bipolar NavierStokes-Poisson system. It is rigorously proved, by introducing the new modulated energy functional and using the refined energy analysis, that ... This paper is concerned with the quasi-neutral limit of the bipolar NavierStokes-Poisson system. It is rigorously proved, by introducing the new modulated energy functional and using the refined energy analysis, that the strong solutions of the bipolar Navier-Stokes-Poisson system converge to the strong solution of the compressible NavierStokes equations as the Debye length goes to zero. Moreover, if we let the viscous coefficients and the Debye length go to zero simultaneously, then we obtain the convergence of the strong solutions of bipolar Navier-Stokes-Poisson system to the strong solution of the compressible Euler equations. 展开更多
关键词 bipolar Navier-Stokes-Poisson system compressible Navier-Stokes equations compressible Euler equations modulated energy functional
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MTF Measurement of EBCCD Imaging System by Using Super Resolution Technique
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作者 左昉 高岳 +2 位作者 高稚允 苏美开 周立伟 《Journal of Beijing Institute of Technology》 EI CAS 2003年第2期125-128,共4页
Existing methods of measurement MTF for discrete imaging system are analysed. A slit target is frequently used to measure the MTF for an imaging system. Usually there are four methods to measure the MTF for a discrete... Existing methods of measurement MTF for discrete imaging system are analysed. A slit target is frequently used to measure the MTF for an imaging system. Usually there are four methods to measure the MTF for a discrete imaging system by using a slit. These methods have something imperfect respectively. But for the discrete imaging systems of under sampling it is difficult to reproduce this type of target properly since frequencies above Nyquist are folded into those below Nyquist, resulting in aliasing effect. To tackle the aliasing problem, a super resolution technique is introduced into our measurement, which gives MTF values both above and below Nyquist more accurately. 展开更多
关键词 EBCCD modulation transfer function super resolution low light level imaging
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Computed Tomography Protocol Optimisation for Pediatric Head Trauma: Radiation Dose and Image Quality Assessment
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作者 Evelyn Anaafi Mary Boadu +2 位作者 Albertina Rusandu Mercy Afadzi Kwame Anokye Amoabeng 《International Journal of Medical Physics, Clinical Engineering and Radiation Oncology》 2022年第3期160-175,共16页
Purpose: Children are sometimes examined with Computed Tomography protocols designed for adults, leading to radiation doses higher than necessary. Lack of optimisation could lead to image quality higher than what is n... Purpose: Children are sometimes examined with Computed Tomography protocols designed for adults, leading to radiation doses higher than necessary. Lack of optimisation could lead to image quality higher than what is needed for diagnostic purposes with associated high doses to patients. Optimising the protocols for paediatric head trauma CT imaging will reduce radiation dose. Objective: The study aimed to optimise radiation dose and assess the image quality for a set of protocols by evaluating noise, a contrast to noise ratio, modulation transfer function and noise power spectrum. Methods: Somaton Sensation 64 was used to scan the head of an anthropomorphic phantom with a set of protocols. ImageJ software was used to analyse the paediatric head image from the scanner. IMPACTSCAN dosimeter software was used to evaluate the radiation dose to the various organs in the head. MATLAB was used to analyse the Modulation Transfer Function and the Noise Power. Results: The estimated Computed Tomography Dose Index volume (CTDI<sub>vol</sub>) increased with increasing tube current and tube voltage. The high pitch of 0.9 gave a lower dose than the 0.5 pitch. The eye lens received the highest radiation dose (39.2 mGy) whiles the thyroid received the least radiation dose (13.7 mGy). There was an increase in noise (62.46) when the H60 kernel was used and a lower noise (8.829) was noticed when the H30 kernel was used. Conclusion: The results obtained show that the H30 kernel (smooth kernel) gave higher values for noise and contrast to noise ratio (CNR) than the H60 kernel (sharp kernel). The H60 kernel produced high values for the modulation transfer function (MTF) and noise power spectrum (NPS). The eye lens received the highest radiation dose. 展开更多
关键词 Image Quality Radiation Dose Modulation Transfer function Noise Power Spectrum OPTIMIZATION
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Simplified modeling of frequency behavior in photonic crystal vertical cavity surface emitting laser with tunnel injection quantum dot in active region
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作者 Mehdi Riahinasab Vahid Ahmadi Elham Darabi 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第2期260-267,共8页
In this work, the characteristics of the photonic crystal tunneling injection quantum dot vertical cavity surface emitting lasers(Ph C-TIQD-VCSEL) are studied through analyzing a modified modulation transfer functio... In this work, the characteristics of the photonic crystal tunneling injection quantum dot vertical cavity surface emitting lasers(Ph C-TIQD-VCSEL) are studied through analyzing a modified modulation transfer function. The function is based on the rate equations describing the carrier dynamics at different energy levels of dot and injector well. Although the frequency modulation response component associated with carrier dynamics in wetting layer(WL) and at excited state(ES) levels of dots limits the total bandwidth in conventional QD-VCSEL, our study shows that it can be compensated for by electron tunneling from the injector well into the dot in TIQD structure. Carrier back tunneling time is one of the most important parameters, and by increment of that, the bias current dependence of the total bandwidth will be insignificant. It is proved that at high bias current, the limitation of the WL-ES level plays an important role in reducing the total bandwidth and results in rollovers on 3-d B bandwidth-I curves. In such a way, for smaller air hole diameter of photonic crystal, the effect of this reduction is stronger. 展开更多
关键词 modulation transfer function photonic crystal(PhC) tunnel injection quantum dot(TIQD) vertical cavity surface emitting laser(VCSEL)
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