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Theory of quenching quantum fluctuations of a laser system with a ladder-type configuration

Physical Review A 2010年第2期81卷 023818-023818页

作者： Deshui Yu Jingbiao Chen []Institute of Quantum Electronics and State Key Laboratory of Advanced Optical Communication System & Network School of Electronics Engineering & Computer Science Peking University Beijing 100871 People’s Republic of China and State Key Laboratory of Precision Spectroscopy East China Normal University Shanghai 200062 People’s Republic of China

The theory of a laser system with a ladder-type configuration is studied in detail based on the quantum Langevin approach. By using an external field to link the lower lasing level with another atomic level, whose decay rate is much larger, laser intensity significantly increases and the quantum-limited linewidth can be quenched. We also discuss the spectrum of fluctuations of the output field, and the result shows that the fluctuations at low frequencies can be much suppressed too. On the other hand, this quenching approach can realize a laser output between two atomic levels, whose decay rates do not satisfy the usual lasing condition that the decay rate of the lower lasing level should be larger than that of the upper lasing level. It will be very useful to realize a laser output with the wavelength we want. This quenching approach has been widely used in the absorption spectrum of the ytterbium optical lattice clock and in the laser cooling approach for calcium atoms. Here we apply it in the stimulated emission of lasers.

关键词： Ladders

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A 2.4GHz monolithic SiGe power amplifier for Wireless-LAN transceiver

A 2.4GHz monolithic SiGe power amplifier for Wireless-LAN tr...

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Asia Pacific Conference on Postgraduate Research in Microelectronics & Electronics (PrimeAsia)

作者： Ying Ruan Lei Chen Yan-hua Liu Feng Ran Zong-sheng Lai Faculty of Computer & Information Engineering Shanghai University of Electrical Power China Institute of Microelectronic Circuit & System East China Jiao Tong University China Key Laboratory of Advanced Display and System Application Ministry of Education Shanghai University Shanghai China

A high-linearity power amplifier (PA) for 2.4 GHz Wireless-LAN transceiver is presented. The PA is designed and implemented using a 0.18 um SiGe BiCMOS process. An on-chip adaptive linearizer is comprised of a base-emitter diode of the bias transistor and a bypass capacitor with almost no increase in die area and no extra dc consumption. Besides the linearization function, the active biasing circuit is also temperature-insensitive with simple structure. Including all matching circuits and biasing circuits, the die area of the fully integrated PA is 1.2 mm * 1.1 mm. Temperature simulation indicates the variation of power gain is less than 1.6dB from 20°C to 80°C. The second-order and third-order LMD are less than -30.9 dBc and -34.5 dBc when the output PI dB has been reached. With 3.3 V supply, the PA achieves max PldB of 23.2 dBm and a power added efficiency (PAE) of 21.3%.

关键词： Power amplifiers Silicon germanium Power generation Radio frequency Power transistors Metals BiCMOS integrated circuits

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Color component feature selection in feature-level fusion based color face recognition

Color component feature selection in feature-level fusion ba...

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IEEE International Conference on Fuzzy systems (FUZZ-IEEE)

作者： Seung Ho Lee Jae Young Choi Konstantinos N. Plataniotis Yong Man Ro Image and Video System Laboratory Korea Advanced Institute of Science and Technology Daejeon South Korea School of Computer Science Ryerson University Toronto ONT Canada Department of Electrical and computer Engineering University of Toronto Toronto ONT Canada

In this paper, we propose a new color face recognition (FR) method which effectively employs feature selection algorithm in order to find the set of optimal color components (from various color models) for FR purpose. The proposed FR method is also designed to improve FR accuracy by combining the selected color components at the feature level. The effectiveness of the proposed color FR method has been successfully demonstrated using two public CMU-PIE and Color FERET face databases (DB). In our comparative experiments, traditional grayscale-based FR, previous color-based FR, and popular local binary pattern (LBP) based FR methods were compared with the proposed method. Experimental results show that our color FR method performs better than the aforementioned three different FR approaches. In particular, the proposed method can achieve 7.81% and 18.57% improvement in FR performance on the CMU-PIE and Color FERET DB, respectively, compared to representative color-based FR solutions previously developed.

关键词： Image color analysis Face Classification algorithms Lighting Feature extraction Principal component analysis Optimized production technology

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High performance FFT on multicore processors

High performance FFT on multicore processors

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International Conference on Cognitive Radio Oriented Wireless Networks and Communications

作者： J. Barhen C. Kotas T. S. Humble P. Mitra N. Imam M. A. Buckner M. R. Moore Center of Engineering Science Advanced Research Computer Science and Mathematics Division Oak Ridge National Laboratory Oak Ridge TN USA RF and Microwave Systems Group Measurement Science & System Engineering Division Oak Ridge National Laboratory Oak Ridge TN USA

Importance of achieving high performance Fourier transforms for Cognitive Radio applications can not be over-emphasized. This includes signal detection in the presence of noise power uncertainty, multi-resolution spectrum sensing, minimization of subcarriers' side lobes in OFDM modulators, multi-stream processing, or spectrum loading, for example. With the emergence of advanced multicore processors, there is a remarkable opportunity to develop novel, massively parallel implementations of the FFT. This paper reviews recent advances in the area, and presents results for three classes of devices: the IBM Cell multi-SIMD processor, the Nvidia Tesla SIMT processor, and the EnLight digital optical core device.

关键词： Object recognition Digital filters MATLAB

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34-fs pulse generation directly from an Er:fiber laser

34-fs pulse generation directly from an Er:fiber laser

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The 5th International Symposium on Ultra-fast Phenomena & Terahertz Waves(第五届超快现象与太赫兹波国际研讨会)

作者： Ding Ma Chun Zhou Yue Cai Weijian Zong Zhigang Zhang Institute of Quantum Electronics State Key Laboratory of Advanced Optical Communication System and NetworksSchool of Electronics Engineering and Computer Science University of Beijing Beijing 100871 P.R.China

We report 34 fs level pulse generation directly from a mode locked Er:fiber laser at a repetition rate of 230 MHz.

关键词： Ultrafast lasers Fiber lasers

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Attribute ranking for lateralizing focal epileptogenicity in temporal lobe epilepsy

Attribute ranking for lateralizing focal epileptogenicity in...

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Iranian Conference of Biomedical engineering (ICBME)

作者： Shobeir Fakhraei Hamid Soltanian-Zadeh Kost Elisevich Farshad Fotouhi Image Analysis Laboratory Department of Radiology Henry Ford Health System Detroit MI USA Department of Computer Science Wayne State University Detroit MI USA CIPCE School of Electrical and Computer Engineering University of Tehran Tehran Iran Department of Neurosurgery Henry Ford Health System Detroit MI USA

A consensus feature-ranking approach has been applied to the study of localization-related temporal lobe epilepsy (TLE) in order to evaluate the relative discriminative power of individual attributes. Cases were selected on the basis of a postoperative outcome free of disabling seizures (i.e., Engel class I) in order to establish a definitive laterality of focal epileptogenicity. Several quantitative measures made available by imaging and electrographic studies are considered and the most discriminative of these are quantitatively prioritized for the lateralization of focal epileptogenicity. Cases requiring extraoperative electrocorticography were examined as a subgroup to establish whether the current method of analysis could distinguish laterality sufficiently well to avoid the requirement for intracranial electrode implantation.

关键词： Electroencephalography Medical diagnostic imaging Epilepsy Data mining Temporal lobe

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Efficient model reduction of interconnects via double gramians approximation 10

Efficient model reduction of interconnects via double gramia...

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Asia and South Pacific Design Automation Conference

作者： Boyuan Yan Sheldon X.-D. Tan Gengsheng Chen Yici Cai Department of Electrical Engineering University of California Riverside CA USA State Key Laboratory of ASIC & System Fudan University Shanghai China Computer Science Department Tsinghua University Beijing China

ISBN: (纸本)9781605588377

The gramian approximation methods have been proposed recently to overcome the high computing costs of classical balanced truncation based reduction methods. But those methods typically gain efficiency by projecting the original system only onto one dominant subspace of the approximate system gramian (for instance using only controllability gramian). This single gramian reduction method can lead to large errors as the subspaces of controllability and observability can be quite different for general interconnects with unsymmetric system matrices. In this paper, we propose a fast balanced truncation method where the system is balanced in terms of two approximate gramians as achieved in the classical balanced truncation method. The novelty of the new method is that we can keep the similar computing costs of the single gramian method. The proposed algorithm is based on a generalized SVD-based balancing scheme such that the dominant subspace of the approximate gramian product can be obtained in a very efficient way without explicitly forming the gramians. Experimental results on a number of published benchmarks show that the proposed method is much more accurate than the single gramian method with similar computing costs.

关键词： Reduced order systems Costs Controllability Approximation methods Error correction Observability Integrated circuit interconnections Large-scale systems Equations Control systems

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Consensus Feature Ranking in Datasets with Missing Values

Consensus Feature Ranking in Datasets with Missing Values

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International Conference on Machine Learning and Applications (ICMLA)

作者： Shobeir Fakhraei Hamid Soltanian-Zadeh Farshad Fotouhi Kost Elisevich Image Analysis Laboratory Department of Radiology Henry Ford Health System Detroit MI USA Department of Computer Science Wayne State University Detroit MI USA CIPCE School of Electrical And Computer Engineering University of Tehran Tehran Iran Department of Neurosurgery Henry Ford Health System Detroit MI USA

Development of a feature ranking method based upon the discriminative power of features and unbiased towards classifiers is of interest. We have studied a consensus feature ranking method, based on multiple classifiers, and have shown its superiority to well known statistical ranking methods. In a target environment such as a medical dataset, missing values and an unbalanced distribution of data must be taken into consideration in the ranking and evaluation phases in order to legitimately apply a feature ranking method. In a comparison study, a Performance Index (PI) is proposed that takes into account both the number of features and the number of samples involved in the classification.

关键词： Accuracy Support vector machines Classification algorithms Niobium Medical diagnostic imaging Data mining

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Face recognition using gabor wavelet and self-adaptive intelligent single particle optimizer

Face recognition using gabor wavelet and self-adaptive intel...

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Chinese Conference on Pattern Recognition

作者： Zhou, Jiarui Ji, Zhen Huang, Weigan Tian, Tao College of Biomedical Engineering and Instrument Science Zhejiang University Hangzhou 310027 China College of Computer Science and Software Engineering Shenzhen University Shenzhen 518060 China Shenzhen Key Laboratory of Embedded System Design Shenzhen 518060 China

ISBN: (纸本)9781424472109

A Gabor wavelet based face recognition algorithm of PSOGabor is introduced in this paper. By using particular Gabor filters in feature extraction on important region of face image, PSOGabor can attain more representative feature information with less processing time. To overcome the drawback of overly dependence on the input parameters in intelligent single particle optimizer (ISPO), an improved algorithm of self-adaptive ISPO (AdpISPO) is proposed in this paper. With no critical parameter required, AdpISPO can achieve higher performance than original algorithms. Experimental results demonstrated that, by employing AdpISPO in Gabor filters' selection, PSOGabor can attain higher recognition rate with less computational time. ©2010 IEEE.

关键词： Face recognition

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A systematic gain setting method of the positive feedback anti-islanding scheme for inverter-based distributed generators

A systematic gain setting method of the positive feedback an...

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International Conference on Power system Technology (POWERCON)

作者： Xiaoyu Wang Shouzhen Zhu Jing Yong Jinghong Zheng Wilsun Xu State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing China Department of Electrical and Computer Engineering University of Alberta Edmonton AB Canada

This paper proposes a systematic gain setting method for the positive feedback anti-islanding scheme which is designed to protect the interconnected inverter-based distributed generators (DGs) from islanding operation. Two main factors affecting the performance of the anti-islanding scheme are investigated when the positive feedback gain is tuned. One is the stability impact of the anti-islanding control on distributed generation (DG) systems and the other is the islanding detection time of the anti-islanding scheme. The small-signal model and the electromagnetic transient simulation model of an inverter-based DG system are developed to facilitate the realization of the proposed gain setting method. This method provides a practical and reliable tool for DG planning engineers.

关键词： Laboratories Electromagnetics

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