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오늘 본 자료
Sparse pseudoinverse incremental extreme learning machine
Kassani, Peyman Hosseinzadeh,Teoh, Andrew Beng Jin,Kim, Euntai Elsevier 2018 Neurocomputing Vol.287 No.-
<P>An extreme learning machine (ELM) is a popular analytic single hidden layer feedforward neural network because of its rapid learning capacity. However, vanilla dense ELMs are affected by the overfitting problem when the number of hidden neurons is high. Further direct consequences of the density are decreases in both the training and prediction speeds. In this study, we propose an incremental method for sparsifying the ELM using a newly devised indicator driven by the condition number in the ELM design matrix, in which we call sparse pseudoinverse incremental-ELM (SPI-ELM). SPI-ELM exhibits better generalization performance and lower run-time complexity compared with ELM. However, the sparsification process may negatively affect the learning speed of SPI-ELM; thus, we introduce an iterative matrix decomposition algorithm to address this issue. We also demonstrate that there is a useful relationship between the condition number in the ELM design matrix and the number of hidden neurons. This relationship helps to understand the random weights and nonlinear activation functions in ELMs. We evaluated the SPI-ELM method based on 20 benchmark data sets from the University of California Irvine repository and three real-world databases from the computer vision domain. (C) 2018 Elsevier B.V. All rights reserved.</P>
Enhancement of Surface Wettability by Intra-Helium Plasma for Liquid Core Fiber Lens
Kassani, Sahar Hosseinzadeh,Khazaeinezhad, Reza,Nazari, Tavakol,Wonho Choe,Kyunghwan Oh IEEE 2014 IEEE photonics technology letters Vol.26 No.20
<P>We generated an atmospheric pressure helium plasma inside a silica hollow optical fiber (HOF) and the surface wettability of the inside wall was flexibly controlled by the plasma intensity. By filling the glycerol into the HOF, we experimentally investigated the surface characteristics by contact angle measurements. Liquid-fiber optic lenses with various numerical apertures were proposed and the light intensity patterns through liquid core lens to the air were investigated numerically.</P>
Kassani, Peyman Hosseinzadeh,Kim, Euntai Korean Institute of Intelligent Systems 2016 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.16 No.2
The proposal of this study is a fast version of the conventional extreme learning machine (ELM), called pseudoinverse matrix decomposition based incremental ELM (PDI-ELM). One of the main problems in ELM is to determine the number of hidden nodes. In this study, the number of hidden nodes is automatically determined. The proposed model is an incremental version of ELM which adds neurons with the goal of minimization the error of the ELM network. To speed up the model the information of pseudoinverse from previous step is taken into account in the current iteration. To show the ability of the PDI-ELM, it is applied to few benchmark classification datasets in the University of California Irvine (UCI) repository. Compared to ELM learner and two other versions of incremental ELM, the proposed PDI-ELM is faster.
Fast response in-line gas sensor using C-type fiber and Ge-doped ring defect photonic crystal fiber.
Kassani, Sahar Hosseinzadeh,Park, Jiyoung,Jung, Yongmin,Kobelke, Jens,Oh, Kyunghwan Optical Society of America 2013 Optics express Vol.21 No.12
<P>An in-line chemical gas sensor was proposed and experimentally demonstrated using a new C-type fiber and a Ge-doped ring defect photonic crystal fiber (PCF). The C-type fiber segment served as a compact gas inlet/outlet directly spliced to PCF, which overcame previous limitations in packaging and dynamic responses. C-type fiber was prepared by optimizing drawing process for a silica tube with an open slot. Splicing conditions for SMF/C-type fiber and PCF/C-type fiber were experimentally established to provide an all-fiber sensor unit. To enhance the sensitivity and light coupling efficiency we used a special PCF with Ge-doped ring defect to further enhance the sensitivity and gas flow rate. Sensing capability of the proposed sensor was investigated experimentally by detecting acetylene absorption lines.</P>
Proposing a GPU based Modified Fuzzy Nearest Neighbor Rule for Traffic Sign Detection
Peyman Hosseinzadeh Kassani,Junhyuk Hyun,Euntai Kim 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
The purpose of this study is introducing a graphical process unit (GPU) implementation of a modified fuzzy nearest neighbor rule useful for traffic sign detection (TSD). The new method tries to detect road signs using color information in order to locate regions of interest. The candidate regions of interest are obtained by color information. Afterward, candidate regions are used for making histogram of oriented gradient (HOG) feature. Finally, the features are fed into the GPU-based modified fuzzy nearest neighbor in order to detect traffic signs. The proposed rule modifies the way for fuzzification of query sample in terms of distances while the conventional fuzzy nearest neighbor (FNN) doesn’t care distance of local neighbors. The accuracy of the proposed method is compared with the state of the arts k-nearest neighbor (k-NN), FNN and support vector machine algorithms on the challenging German traffic sign detection benchmark (GTSDB) data set. Results indicate that the modified rule achieves good accuracy and is competitive compared to others.
Peyman Hosseinzadeh Kassani,Euntai Kim 한국지능시스템학회 2016 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.16 No.2
The proposal of this study is a fast version of the conventional extreme learning machine (ELM), called pseudoinverse matrix decomposition based incremental ELM (PDI-ELM). One of the main problems in ELM is to determine the number of hidden nodes. In this study, the number of hidden nodes is automatically determined. The proposed model is an incremental version of ELM which adds neurons with the goal of minimization the error of the ELM network. To speed up the model the information of pseudoinverse from previous step is taken into account in the current iteration. To show the ability of the PDI-ELM, it is applied to few benchmark classification datasets in the University of California Irvine (UCI) repository. Compared to ELM learner and two other versions of incremental ELM, the proposed PDI-ELM is faster.
Khazaeinezhad, Reza,Kassani, Sahar Hosseinzadeh,Hwanseong Jeong,Nazari, Tavakol,Dong-Il Yeom,Kyunghwan Oh IEEE 2015 IEEE photonics journal Vol.7 No.1
<P>We demonstrate an all-fiberized mode-locked laser by employing Molybdenum Disulfide (MoS<SUB>2</SUB>) spin-coated onto a side-polished fiber (SPF) as an in-line saturable absorber. Single crystal MoS<SUB>2</SUB> has been exfoliated via the Li intercalation method and then dispersed with large population of few-layer MoS<SUB>2</SUB> nano-sheets in ethanol. Subsequently, a saturable absorber has been prepared using a relatively simple method: spin-coating the uniform MoS<SUB>2</SUB> solution on the fabricated SPF without using any polymer or toxic procedure. Power-dependent transmission property of the prepared MoS<SUB>2</SUB> nano-sheets on the SPF was experimentally analyzed, providing the feasibility to apply it as an efficient in-line saturable absorption behavior. By deploying the MoS<SUB>2</SUB> SPF into a fiber laser cavity with finely tuned laser pump power and cavity dispersion, mode-locked pulses were obtained at anomalous and normal dispersion of the laser cavity. The self-started soliton pulses at the anomalous dispersion regime were generated with a spectral bandwidth of 9.96 nm at 1584 nm and a pulse duration of 521 fs. Moreover, by managing the dispersion to the normal regime, stable pulses at net-normal intra-cavity dispersion with 11.9 ps pulse duration were obtained with a spectral bandwidth of 18.2 nm at 1570 nm. The results prove the effectiveness of developing MoS<SUB>2</SUB> saturable absorbers and applications for pulsed laser operation.</P>
Khazaeizhad, Reza,Kassani, Sahar Hosseinzadeh,Jeong, Hwanseong,Yeom, Dong-Il,Oh, Kyunghwan Optical Society of America 2014 Optics express Vol.22 No.19
<P>Application of a multilayer Molybdenum Disulfide (MoS2) thin film as a saturable absorber was experimentally demonstrated by realizing a stable and robust passive mode-locked fiber laser via the evanescent field interaction between the light and the film. The MoS2 film was grown by chemical vapor deposition, and was then transferred to a side polished fiber by a lift-off method. Intensity-dependent optical transmission through the MoS2 thin film on side polished fiber was experimentally observed showing efficient saturable absorption characteristics. Using erbium doped fiber as an optical gain medium, we built an all-fiber ring cavity, where the MoS2 film on the side polished fiber was inserted as a saturable absorber. Stable dissipative soliton pulse trains were successfully generated in the normal dispersion regime with a spectral bandwidth of 23.2 nm and the pulse width of 4.98 ps. By adjusting the total dispersion in the cavity, we also obtained soliton pulses with a width of 637 fs in the anomalous dispersion regime near the lasing wavelength 관 = 1.55 관m. Detailed and systematic experimental comparisons were made for stable mode locking of an all-fiber laser cavity in both the normal and anomalous regimes.</P>
Khazaeinezhad, Reza,Kassani, Sahar Hosseinzadeh,Hwanseong Jeong,Kyung Jun Park,Byoung Yoon Kim,Dong-Il Yeom,Kyunghwan Oh IEEE 2015 IEEE photonics technology letters Vol.27 No.15
<P>We demonstrate all-fiber mode-locked laser based on a tapered optical fiber saturable absorber (SA) enclosed in tungsten disulfide (WS<SUB>2</SUB>) nanosheets. Tapered fibers were fabricated using the standard flame brushing method to an interaction length of 3 mm with waist diameters of 10 and 15 μm. WS<SUB>2</SUB> nanosheets were prepared via a liquid phase exfoliation method to form a uniform dispersion. Subsequently, the WS<SUB>2</SUB> nanosheets were optically deposited along the interaction length of the tapered fibers by evanescent field interactions. We built a ring laser including the fabricated mode-lockers. The SA with a 10-μm taper diameter delivers the pulses with a pulse duration of 369 fs and 3-dB spectral bandwidth of 7.5 nm; on the other hand, the output pulses using the mode-locker with 15-μm waist diameter were found to have 563-fs pulse duration and 5.2 nm of 3-dB bandwidth. It is shown that the smaller waist diameter of tapered fiber causes wider spectral bandwidth of the ultrafast pulses and narrower 3-dB bandwidth.</P>