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 dec...
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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.
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-em...
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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%.
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....
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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.
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 spec...
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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.
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 selec...
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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.
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 th...
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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.
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 classifier...
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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.
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 representat...
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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...
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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.
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