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An investigation of thermal effects in a high power 3–5μm solid state laser pumped with different pump beam transverse profiles is carried out by COMSOL software based on the finite element method, and the temperature of the crystal center where the Super-Gaussian distributed light projected area is 81.8 °C, and is bigger than that of Gaussian pump light mode and top plane pump light mode.
In this work, we report on the effects of reverse gate bias step stress on the degradation of AlGaN/GaN high electron mobility transistors (HEMTs), consisting of a decrease in the drain current (IDS) and an increase in channel resistance (Ron). It was found that these degradations were accompanied with an anomalous decrease of gate current (Igoff). Interestingly, the nature of the degradation mentioned...
In this paper, the reliability in AlGaN/GaN HEMTs has been assessed by analyzing the spatial intensity distribution of electroluminescence (EL) detected by Photo Emission Microscope (PEM) during the OFF-state step-stress experiment. And it is found that a relationship between breakdown point and hot spots was confirmed. In addition, we report on the different of EL image before and after failure....
Social networking site (SNS) has become pervasive in the life of the majority of the younger generations. Most of our students spend plenty of their time in interacting with their peers in their favorite SNSs. Many of them have already created their habit of visiting Facebook (currently, the most popular SNS) on a regular basis, some even with their Facebook connection always on. Taking the advantage...
We demonstrate an optically switchable all-fiber optical polarizer based on a side-polished fiber (SPF) overlaid with a photoresponsive liquid crystal (PLC) containing a nematic LC and a photosensitive azobenzene molecule. The trans-cis photoisomerization of azobenzene modulates the overlaid LC's birefringence, changes the refractive index (RI) of the PLC-overlaid SPF, and further controls the polarization...
Classification is one of the most important issues in microarray data analysis. Due to the SSS problem and other properties of microarray data, how to select the differentially expressed genes and how a build a proper classification model according these selected genes are two crucial concerns in constructing a powerful classification scheme. In this study, a classification scheme named SVMSC is proposed...
In high-dimensional data classification, the method employed should be both powerful and robust against the SSS (small sample size) problem. LDA is a classical, efficient, and powerful feature extraction method that can be applied to effectively reduce the feature space dimension and thus ease the adverse effect of the SSS problem. However, LDA itself suffers from the SSS problem due to the nature...
Class imbalance problem has attracted many attentions in recent years. When the available training sample size of each class is imbalanced, the directly established classification model will tend to allocate the testing sample into the majority class. A proper resampling method together with a power classifier is generally employed for dealing with this problem. Many multi-classifier ensembles have...
High power laser diodes have found wide spread applications as pump sources for solid state lasers or in direct material processing. Due to the high electrical and optical power densities in the laser structures the reliability is still questionable. We report on lifetime testing of a high power cm-bar arrays using an automated diode array reliability experiment. This computer controlled setup operates...
Multimedia applications like retrieval, copy detection etc. can gain from saliency detection, which is essentially a method to identify areas in images and videos that capture the attention of the human visual system. In this paper, we propose a new spatiotemporal saliency framework for videos based on sparse representation. For temporal saliency, we model the movement of the target patch as a reconstruction...
This paper realizes a humanoid robotic system to execute target grasping (TG) in the 3-D world coordinate. At the outset, the HR scans the field to find specific target(s), which is (are) randomly distributed in the 3-D coordinate before the HR. By an active stereo vision system (ASVS), the HR is navigated to the planned posture and then the task of TG is executed. The first feature of this paper...
Lifetime is a key parameter for electronic products using, and how to obtain the lifetime by using a short-term aging data has become a challenging issue. In this paper, a new aging data analysis method will be introduced, and three groups of aging data for high power laser diodes will be as a case to expound this method. The aging test time will be greatly decreased by using this method.
GaAs PHEMT are used abroad in high temperature and high power RF/Microwave field; it is the most promising microwave devices. In long-term use, the PHEMT device may cause parameter drift and output power decrease. In this paper, based on the analysis of device structure and degradation mechanism, we design structure doing high-temperature accelerated lift testing, and analyze using SIMS, FIB, EM and...
High-speed network traffic is characterized by high burstiness and high randomness. Extensive test and analytical results show that high-speed network traffic has the statistical characteristic of Long-Range Dependence (LRD) or self-similarity. All traffic sampling measurement methods adopted currently are based on sampling algorithms in pure mathematical theories without consideration of the behavioral...
Orthogonal frequency division multiplexing (OFDM) combining with the coordinated multi-point (CoMP) transmission technique has been proposed to improve performance of the receivers located at the cell border. However, the inevitable carrier frequency offset (CFO) will destroy the orthogonality between subcarriers and induce strong inter-carrier interference (ICI) in OFDM systems. In a multi-point...
Wireless Sensor Network (WSN) is still a hottest research topic which can be applied to a lot of new research field such as robotic and smart grid. Its not only used for detecting the new environment but also monitoring any situation which has dynamic variation. However, the sensor node is relied on the battery energy that limited the lifetime of entire network. In this paper, we proposed a novel...
With the development of the RF/microwave technology, more and more GaAs PHEMT device is used and the power of the device is also increasing. However, the test of thermal performance and heat dissipation in packaging device is still a prominent problem. In order to obtain steady operation and longer lifetime, what is the highest temperature environment the device can work? Also the package of the device...
Modeling and simulation of gas turbines was a hot research direction at home and abroad. In this paper, micro-turbojet JetCAT-P80, a aviation gas turbine, was took as the research object, which the thermodynamic parameters of the various sections and the engine performance parameters of the design conditions were solved with the Matlab software. On this basis, GasTurb, a system-level modeling and...
An evaluation structure about gate metal degradation of pseudomorphic High-Electron Mobility Transistor (PHEMT) is designed in this study. It realized separated evaluation of the resisted electromigration levels between the evaporation metal Ti/Pt/Au and the plating metal Au in gate metal structure. There are 4 multiple disparities between their resisted electromigration levels. And the resisted electromigration...
The geological disaster often loses pipeline security to finished oil having bigger effect, from the geology angle studying the effect to the pipeline duty such as landslide, mud-rock flow (geology disaster) being unlike area, and then being that the pipeline is safe work and manage provide scientific basis. The article has analyzed the form and cause and disaster occurrence serious consequences that...
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