共查询到19条相似文献,搜索用时 125 毫秒
1.
《中国物理 B》2018,(12)
In this article, unique spectral features of short-wave infrared band of 1 μm–3 μm, and various applications related to the photodetectors and focal plane arrays in this band, are introduced briefly. In addition, the different material systems for the devices in this band are outlined. Based on the background, the development of lattice-matched and wavelengthextended InGaAs photodetectors and focal plane arrays, including our continuous efforts in this field, are reviewed. These devices are concentrated on the applications in spectral sensing and imaging, exclusive of optical fiber communication. 相似文献
2.
The Optical properties and spectral data of erbium-doped Lithium Niobate crystals,including absorption spectrum, emission spectrum, luminescence lifetime and up-conversion effects are reported in this paper. The energy level scheme, Stark splitting under crystal field and up-conversion mechanism are discussed in detail. The possible applications of this material in waveguide optics and opto-electronics are also prospected. 相似文献
3.
《中国物理 B》2015,(11)
Planar Bragg reflector operating in the sub-terahertz wavelength installed at the upstream end of a sheet beam backward wave oscillator(BWO) is very promising to minimize the whole circuit structure and make it more compact. In this paper, a sub-terahertz wavelength(0.18–0.22 THz) tunable planar Bragg reflector is numerically analyzed by using multi-mode coupling theory(MCT). The operating mode TE10 and dominant coupling mode TE01 are mainly considered in this theory. Reflection and transmission performance of the reflector are demonstrated in detail and the results, in excellent agreement with the theoretical analysis and simulation, are also presented in this paper. Self- and cross-coupling coefficients between these two modes are presented as well. The reflector behaviors with different Bragg dimensions are discussed and analyzed in the 0.16–0.22 THz range. The analysis in this paper can be of benefit to the design and fabrication of the whole BWO circuit. 相似文献
4.
兰军 《声学学报:英文版》1987,(2)
The author had proposed the successive approximation method in order to solve problems ondirectivity synthesis.In this paper this method is developed and perfected further.Some conclusions in thismethod are proved theoretically.The physical meaning and the optimum characteristic of this method areclarified.The fitting way and the fitting condition between synthesized functions and expected function arediscussed in detail.Some basic properties of directivity functions are discussed. 相似文献
5.
An improved quantum secure direct communication (QSDC) protocol is proposed in this paper.Blocks of entangled photon pairs are transmitted in two steps in which secret messages are transmitted directly.The single logical qubits and unitary operations under decoherence free subspaces are presented and the generalized Bell states are constructed which are immune to the collective noise.Two steps of qubit transmission are used in this protocol to guarantee the security of communication.The security of the protocol against various attacks are discussed. 相似文献
6.
We are entering a new era of gravitational-wave astronomy. The ground-based interferometers have reached their initial design sensitivity in the audio band. Several upper limits have been set for anticipated astrophysical sources from the science data. The advanced detectors in the US and in Europe are expected to be operational around 2015. New advanced detectors are also planned in Japan and in India. The first direct detections of gravitational waves are expected within this decade. In the meanwhile, three pulsar timing array projects are forming an international collaboration to detect gravitational waves directly in the nanoHertz range using timing data from millisecond pulsars. The first direct detection of nanoHertz gravitational waves are also expected within this decade. In this paper, we review the status of current gravitational-wave detectors, possible types of sources, observational upper limits achieved, and future prospects for direct detection of gravitational waves 相似文献
7.
In this paper, the symmetry method has been carried over to the generalized variable coefficients Zakharov- Kuznetsov equation. The infinitesimal symmetries and the optimal system are deduced and from this optimal system seven basic fields are determined, and for every vector field in the optimal system the admissible forms of the coefficients are found and this also leads us to transform the given equation into partial differential equations in two variables. After using some referenced transformations the mentioned partial differential equations eventually reduce to ordinary differential equations. The search for solutions to those equations has yielded many exact solutions in most cases. 相似文献
8.
In this paper, we consider multi-agent consensus problems
in a decentralised fashion. The interconnection topology graph among
the agents is switching and undirected. The agent dynamics is
expressed in the form of a double integrator model. Two different
cases are considered in this study. One is the leader-following case
and the other is leaderless case. Based on graph theory and common
Lyapunov function method, some sufficient conditions are obtained
for the consensus stability of the considered systems with the
neighbour-based feedback laws in both leader-following case and
leaderless case respectively. Finally, two numerical examples are
given to illustrate the obtained results. 相似文献
9.
Higher-order differential variational principle and differential equations of motion for mechanical systems in event space
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In this paper we study the higher-order differential variational principle and differential equations of motion for mechanical systems in event space. Based on the higher-order d'Alembert principle of the system, the higher-order velocity energy and the higher-order acceleration energy of the system in event space are defined, the higher-order d'Alembert- Lagrange principle of the system in event space is established, and the parametric forms of Euler-Lagrange, Nielsen and Appell for this principle are given. Finally, the higher-order differential equations of motion for holonomic systems in event space are obtained. 相似文献
10.
The generalized Riccati equation vational expansion method is extended in this paper. Several exact solutions for the generalized Burgers-Fisher equation with variable coefficients are obtained by this method, and some of which are derived for the first time. It is concluded from the results that this approach is simple and efficient even in solving partial differential equations with variable coefficients. 相似文献
11.
实验研究了装有Pt覆盖的多孔陶瓷的Swiss-Roll燃烧器的燃烧特性,分别得到了3种不同长度的催化剂基底的熄火极限,并测量3种情况下催化剂壁面及催化剂后部空间的温度。实验结果表明,3种情况中,催化剂基底长4.5mm的燃烧器可燃范围最大,所以此长度较适合此Swiss-Roll燃烧器。从温度数据可以看出来,催化剂后部空间存在反应,且受上游催化剂表面反应强度的影响。 相似文献
12.
A surface detection or 3D profilometry for microstructure (millimeter size) based on the project grating method and phase measurement techniques is presented in this paper. The advantages of this technique are simple measuring apparatus, full field and almost real-time testing. The principle and theoretical analysis of the measuring sensitivity are described and four application examples including a calibration example are also presented in this paper. Further improvement and probable applications in electronic industry are also discussed. 相似文献
13.
针对具有电大尺寸、厚介质罩且馈源采用特定模式激励的高功率微波(HMP)传输及辐射结构研究了一种新型的电磁建模技术。将模式匹配方法与积分方程方法进行混合,构建了电磁模型的方程组,采用多层快速多极子技术、预条件器等进行求解加速,最终形成了可对电大尺寸HPM传输、辐射系统进行高效全波电磁仿真的技术。以电大变张角喇叭馈源、功率合成天线、波束波导及波束波导天线作为实例,构建了几何及电磁模型,并进行了包括远区方向图、近区功率密度分布在内的数值模拟,对该技术的正确性和通用性进行了验证。结果表明,该技术边界拟合准确,内存消耗低,且对馈电模式能予以准确反映,适用于HPM传输发射的高效高精度模拟。 相似文献
14.
利用激光激发原子荧光光谱方法分析海洋沉积物样品中的痕量钯 总被引:2,自引:0,他引:2
本文介绍了激光激发原子荧光光谱分析方法及实验谱仪装置,利用这套谱仪共对36个我国东海大陆架沉积物样品中的钯进行了分析测量。 相似文献
15.
Chandan Dasgupta 《Pramana》2005,64(5):679-694
Theoretical approaches to the development of an understanding of the behaviour of simple supercooled liquids near the structural
glass transition are reviewed and our work on this problem, based on the density functional theory of freezing and replicated
liquid state theory, are summarized in this context. A few directions for further work on this problem are suggested. 相似文献
16.
A. M. W. Verhagen 《Journal of statistical physics》1976,15(3):219-231
An anisotropic triangular Ising model in which the first- and second-order parameters and the field parameters are functionally related is solved exactly by representing the distribution of the atom patterns in terms of a suitably constructed Markov process. The probabilities of patterns, defined as the probabilities generated by this process, are a mathematically tractable alternative to the classical representation of these probabilities in terms of the partition function. The interaction and field parameters of this Ising model, its magnetization, free energy, and its nearest neighbor correlation functions, are expressed in terms of the parameters of this Markov process. Special cases are worked out in detail and numerical examples are given. 相似文献
17.
18.
Applications of modularized circuit designs in a new hyper-chaotic system circuit implementation
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Modularized circuit designs for chaotic systems are introduced in this paper.Especially,a typical improved modularized design strategy is proposed and applied to a new hyper-chaotic system circuit implementation.In this paper,the detailed design procedures are described.Multisim simulations and physical experiments are conducted,and the simulation results are compared with Matlab simulation results for different system parameter pairs.These results are consistent with each other and they verify the existence of the hyper-chaotic attractor for this new hyper-chaotic system. 相似文献