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.
The hybrid excitation permanent magnet machine (HEPMM) combines two kinds of excitation: permanent magnet (PM) and electrical excitation, so it possesses the advantages of PM machines and overcomes the incapability of...
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The hybrid excitation permanent magnet machine (HEPMM) combines two kinds of excitation: permanent magnet (PM) and electrical excitation, so it possesses the advantages of PM machines and overcomes the incapability of regulating the excitation field. By now many HEPMM schemes have been presented. In this paper the operation principle, structure, advantages and disadvantages of these HEPMMs have been reviewed and compared in detail. These HEPMMs are classified into three types by new classification method - placement of PM and iron poles. At last novel harmonic excitation HEPMM is proposed and discussed.
Chaotic synchronization criteria for a class of dynamical networks with each node being RCL-shunted Josephson junction is proposed in this paper. The proposed algorithms, which are established in terms of linear matri...
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Chaotic synchronization criteria for a class of dynamical networks with each node being RCL-shunted Josephson junction is proposed in this paper. The proposed algorithms, which are established in terms of linear matrix inequalities (LMIs), guarantee the synchronized states to be global asymptotically stable. In addition, an interesting conclusion is reached that the chaotic synchronization in the coupled whole 3N-dimensional networks can be converted into that of 3-dimensional space.
In this paper, we consider a novel Three Hierarchical decomposition approach for Multi-Player Pursuit Evaders (MPPE) game. In multi-player pursuit evasion game, hierarchical framework is applied widely in order to...
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ISBN:
(纸本)9781424479573
In this paper, we consider a novel Three Hierarchical decomposition approach for Multi-Player Pursuit Evaders (MPPE) game. In multi-player pursuit evasion game, hierarchical framework is applied widely in order to decompose the original complicated multiplayer game into multiple small scale games. In this paper, we first study the number of pursuers which necessitates;the capture condition and the time of all evaders have been captured. Then, describe the Distributed Task Assignment Stage Based on dynamic Coalition Formation. Last, a novel multi-agent Qlearning approach based on Evolutionary Game Theoretic model is used for pursue. Experimental results obtained on two different environments of a well-known pursuit domain show the effectiveness and robustness of the proposed Hierarchical architecture and learning approach.
An event based runoff and erosion process model was developed to analyze the runoff and sediment processes in watershed networks. In this model, watershed was divided into hillslopes and channels and a system mathemat...
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ISBN:
(纸本)9781617388354
An event based runoff and erosion process model was developed to analyze the runoff and sediment processes in watershed networks. In this model, watershed was divided into hillslopes and channels and a system mathematic model capable of simulating runoff, erosion and sediment transportation process in channels and hillslopes was established. The linear reservoir models of watershed response and rainfall momentum methods were used to simulate the runoff and erosion in distributed hillslopes. In the channel network system, the runoff and sediment processes were formulated in three main equations as mass conservation, momentums conservation, and sediment continuity. The hillslope and channel network systems are coupled by sink and sources items of channel's mass and sediment continuity equations. The sources are calculated according to runoff and transported sediment from distributed hillslopes plots along the channels. Finite element method (FEM) was applied to numerically simulate runoff and sediment processes with Visual C++ Programming. ArcSWAT watershed delineation tool was adopted to obtain the Geographic information from the digital elevation model for element formation of finite element method and geographic parameters of model input. The outputs of the model included time and spatial dependent flow rates, sediment concentrations in watershed channels network. The study provided a useful tool to investigation of hydrologic and soil erosion model in watershed.
With the development of remote sensing technologies, computer friendly systems for the display and analysis of global geospatial information become more and more important. This paper concerns a method for computer re...
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ISBN:
(纸本)9781424473014
With the development of remote sensing technologies, computer friendly systems for the display and analysis of global geospatial information become more and more important. This paper concerns a method for computer representation and manipulation of global data based on multi-resolution subdivisions of regular polyhedra. A simple and efficient indexing of the cells of such a subdivision, called A3-coordinates, is introduced. These can be used to encode the 18 · 4 n+1 - 32 cells at the nth level of resolution of the octahedral aperture 4 hexagonal discrete global grid using 2n + 3 bits.
Ad hoc networks, which are multi-hop and autonomous decentralized networks, have broad perspective in military communication, emergency communication, sensor networks and so on. Enhancing the performance of Ad hoc net...
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Ad hoc networks, which are multi-hop and autonomous decentralized networks, have broad perspective in military communication, emergency communication, sensor networks and so on. Enhancing the performance of Ad hoc networks is one of the important objectives in the design of networks while congestion is a significant contributor that leads to network performance degradation. Many different congestion control strategies in transport layer, network layer, MAC layer and even cross-layer have been widely researched. Jian Liu et al. bring forward ATCP to improve traditional TCP congestion control in ad hoc networks (Liu and Signh, 2001). Reference (Shift et al., 2009) proposes a MAC layer congestion control mechanism which mainly uses the congestion window to control the MAC's sending rate in 802.11 WLANs. D. Kliazovich and F. Granelli(Dzmitry and Fabrizio, 2006) research a crosslayer congestion control scheme, in which transport layer's data stream is adjust by the information of link layer, such as bandwidth and delay. The essential reason causing congestion is that user data rate exceeds link data transmit rate capability. Most of the congestion control strategies research how to control user data rate properly to achieve the goal. However, in this paper we investigate MAC layer intelligent split-stream scheme to improve data transmit rate capability for alleviating congestion in Ad hoc networks. In a practical Ad hoc network, due to terrain and interference, link qualities of the paths to some nodes are quite good while those to others are relatively bad. Single node conventionally selects good path expecting great performance of itself. However, multi-nodes all select good path often cause severe competition at MAC, which eventually lead to performance degradation of the whole network.
We investigate a four-level superradiant laser whose intensity is proportional to N2 and whose linewidth scales as 1/N2. In the absence of spontaneous emissions, we derive the stationary solutions of the atomic full c...
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We investigate a four-level superradiant laser whose intensity is proportional to N2 and whose linewidth scales as 1/N2. In the absence of spontaneous emissions, we derive the stationary solutions of the atomic full cooperativity, analyze their stabilities, and find the corresponding irreducible representation based on group U(4). We also investigate the spectra of the phase and amplitude fluctuations of the fields inside and outside the cavity and find that the amplitude fluctuations of the output fields cannot be squeezed in the low-frequency limit, which is completely different from the three-level superradiant laser system. Finally, we consider the stationary solutions corresponding to the partial cooperativity due to the symmetry breaking of U(4) induced by the atomic spontaneous emissions.
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