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The electrical properties of sulfur-implanted cubic boron nitride thin films

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Chinese Physics B 2012年第4期21卷 458-460页

作者：邓金祥秦扬孔乐杨学良李廷赵卫平杨萍 college of applied sciences Beijing University of TechnologyBeijing 100124China

Cubic boron nitride （c-BN） thin films are deposited on p-type Si wafers using radio frequency （RF） sputtering and then doped by implanting S ions. Wile implantation energy of the ions is 19 keV, and the implantation dose is between 1015 ions/cm2 and 1016 ions/cm2. The doped c-BN thin films are then annealed at a temperature between 400℃ and 800℃. The results show that the surface resistivity of doped and annealed c-BN thin films is lowered by two to three orders, and the activation energy of c-BN thin films is 0.18 eV.

关键词： cubic boron nitride ion implantation surface resistivity activation energy

Observation of self-Q-switching in bulk Yb:GdYSiO laser

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Chinese Physics B 2018年第4期27卷 309-312页

作者： Shuang Gong Jin-Rong Tian He-Yang Guo Yu Zi-Kai Dong Chang-Xing Xu Wen-Ping Zhang Yan-Rong Song college of applied sciences Beijing University of Technology Beijing 100124 China

We report the first self-Q-switched Yb-doped GdYSiO5（Yb：GYSO） laser operating at 1080 *** Q-switched pulses with a repetition rate of 18.1 k Hz and pulse duration of 9.45 μs are obtained.A maximum average output power of452.6 m W is achieved with a 1% transmission output *** a 3% transmission output coupler,the shortest pulse width of 6.6 μs is *** demonstrates that Yb：GYSO crystal can be simultaneously employed as a saturable absorber and a gain medium to generate microsecond Q-switched pulses in the near infrared region.

关键词： self-Q-switching Yb:GYSO saturable absorber

Multi-wavelength colloidal quantum dot lasers in distributed feedback cavities

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Science China(Information sciences) 2020年第8期63卷 210-216页

作者： Anwer HAYAT Junhua TONG Chao CHEN Lianze NIU Gohar AZIZ Tianrui ZHAI Xinping ZHANG Institute of Information Photonics Technology and college of applied sciences Beijing University of Technology

Lasers with multi-wavelength colloidal quantum dots(CQDs) can be achieved using complex grating structures and flexible substrate. The structure contains graduated periods and rectangular cavity fabricated through interference lithography, which acts as the distributed feedback cavity. A layer of densely packed CQD film is deposited on the cavity via spin coating technique. The performance of CQD lasers based on different distributed feedback cavities is investigated. Multi-wavelength lasing is achieved based on a flexible rectangular cavity.

关键词： multi-wavelength quantum dots lasers distributed feedback flexible tunable

Systematical analysis of mode-locked fiber lasers using single-walled carbon nanotube saturable absorbers

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Chinese Physics B 2014年第6期23卷 221-227页

作者：张晓宋晏蓉 Institute of Information Photonics Technology and college of applied sciences Beijing University of Technology

The output characteristics of the Er-doped mode-locked fiber laser using a single-walled carbon nanotube saturable absorber are investigated theoretically with a nonlinear Schrtidinger equation and a saturable absorption equation using realistic parameters. Stable self-starting mode-locking pulses are achieved under net normal, net zero, and net anomalous cavity group velocity dispersion （GVD） respectively. A spectrum with a flat top is obtained from the net normal cavity GVD laser while a spectrum with Kelly side-bands is obtained from the net anomalous cavity GVD laser. The characteristics of the pulse duration changing with cavity GVD and modulation depth of the single-walled carbon nanotubes are discussed. The characteristics of the mode-locking pulses from net normal, net zero, and net anomalous cavity GVD mode-locked fiber lasers are compared. These systematical results are useful for designing mode-locked fiber lasers with saturable absorbers made by different kinds of carbon nano-materials.

关键词： mode-locked fiber lasers carbon nanotubes theory

VARIABLE SELECTION FOR COVARIATE ADJUSTED REGRESSION MODEL

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Journal of Systems Science & Complexity 2014年第6期27卷 1227-1246页

作者： LI Xuejing DU Jiang LI Gaorong FAN Mingzhi college of applied sciences Beijing University of Technology Department of Mathematics Xuchang University

This paper employs the SCAD-penalized least squares method to simultaneously select variables and estimate the coefficients for high-dimensional covariate adjusted linear regression *** distorted variables are assumed to be contaminated with a multiplicative factor that is determined by the value of an unknown function of an observable *** authors show that under some appropriate conditions,the SCAD-penalized least squares estimator has the so called "oracle property".In addition,the authors also suggest a BIC criterion to select the tuning parameter,and show that BIC criterion is able to identify the true model consistently for the covariate adjusted linear regression *** studies and a real data are used to illustrate the efficiency of the proposed estimation algorithm.

关键词： BIC covariate adjusted regression model oracle property variable selection.

***,vision-based navigation and the PG master’s degree programme at HfT Stuttgart

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Geo-Spatial Information Science 2023年第2期26卷 156-159页

作者： Michael Hahn Faculty of Geomatics Computer Science and MathematicsStuttgart University of Applied SciencesStuttgartGermany

The two topics of the article seem to have absolutely nothing to do with each other and,as can be expected in a contribution in honor and memory of *** Ackermann,they are linked in his ***-based Navigation was the focus of the doctoral thesis written by the author,the 29th and last PhD thesis supervised by *** International Master’s Program Photogrammetry and Geoinformatics,which the author established with colleagues at Stuttgart University of applied sciences(HfT Stuttgart)in 1999,was a consequence of ***’s benevolent promotion of international knowledge transfer in *** topics are reflected in this article;they provide further splashes of color in ***’s oeuvre.

关键词： Vision-based navigation visual odometry photogrammetry and geoinformatics international master’s degree program

A Novel Action Transformer Network for Hybrid Multimodal Sign Language Recognition

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computers, Materials & Continua 2023年第1期74卷 523-537页

作者： Sameena Javaid Safdar Rizvi Department of computer sciences School of Engineering and Applied SciencesBahria UniversityKarachi CampusKarachiPakistan

Sign language fills the communication gap for people with hearing and speaking *** includes both visual modalities,manual gestures consisting of movements of hands,and non-manual gestures incorporating body movements including head,facial expressions,eyes,shoulder shrugging,*** both gestures have been detected;identifying separately may have better accuracy,butmuch communicational information is *** sign language mechanism is needed to detect manual and non-manual gestures to convey the appropriate detailed message to *** novel proposed system contributes as Sign LanguageAction Transformer Network(SLATN),localizing hand,body,and facial gestures in video *** we are expending a Transformer-style structural design as a“base network”to extract features from a spatiotemporal *** impulsively learns to track individual persons and their action context inmultiple ***,a“head network”emphasizes hand movement and facial expression simultaneously,which is often crucial to understanding sign language,using its attention mechanism for creating tight bounding boxes around classified *** model’s work is later compared with the traditional identification methods of activity *** not only works faster but achieves better accuracy as *** achieves overall 82.66%testing accuracy with a very considerable performance of computation with 94.13 Giga-Floating Point Operations per Second(G-FLOPS).Another contribution is a newly created dataset of Pakistan Sign Language forManual and Non-Manual(PkSLMNM)gestures.

关键词： Sign language gesture recognition manual signs non-manual signs action transformer network

IMPROVED ESTIMATES OF THE COVARIANCE MATRIX IN GENERAL LINEAR MIXED MODELS

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Acta Mathematica Scientia 2010年第4期30卷 1115-1124页

作者：叶仁道王松桂 college of Economics Hangzhou Dianzi University college of applied sciences Beijing University of Technology

In this article, the problem of estimating the covariance matrix in general linear mixed models is considered. Two new classes of estimators obtained by shrinking the eigenvalues towards the origin and the arithmetic mean, respectively, are proposed. It is shown that these new estimators dominate the unbiased estimator under the squared error loss function. Finally, some simulation results to compare the performance of the proposed estimators with that of the unbiased estimator are reported. The simulation results indicate that these new shrinkage estimators provide a substantial improvement in risk under most situations.

关键词： Covariance matrix shrinkage estimator linear mixed model eigenvalue

Underwater Image Enhancement Using Customized CLAHE and Adaptive Color Correction

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computers, Materials & Continua 2023年第3期74卷 5157-5172页

作者： Mousa Alhajlah college of applied computer Science King Saud UniversityRiyadhSaudi Arabia

Underwater images degraded due to low contrast and visibility ***,it is important to enhance the images and videos taken in the underwater environment before *** is a way to improve or increase image quality and to improve the contrast of degraded *** original image or video which is captured through image processing devices needs to improve as there are various issues such as less light available,low resolution,and blurriness in underwater images caused by the normal *** researchers have proposed different solutions to overcome these *** channel prior(DCP)is one of the most used techniques which produced a better Peak Signal to Noise Ratio(PSNR)***,DCP has some issues such as it tends to darken images,reduce contrast,and produce halo *** proposed method solves these issues with the help of contrast-limited adaptive histogram equalization(CLAHE)and the Adaptive Color Correction *** proposed method was assessed using Japan Agency for Marine-Earth Science and Technology(JAMSTEC),and some images were collected from the *** measure of entropy(MOE),Measure of Enhancement(EME),Mean Square Error(MSE),and PSNR opted as performance measures during *** values of MSE and PSNR achieved by the proposed framework are 0.26 and 32 respectively which shows better results.

关键词： Enhancement color diminishing contrast fusion technique color balancing technique CLAHE dark channel prior