双向中继网络中基于压缩感知的稀疏信道估计

为提高双向中继网络中稀疏信道估计的精度并减少训练序列的长度, 利用双向中继信道(Two-way Relay Channel, TWRC)的潜在稀疏特性, 研究了基于压缩感知的稀疏TWRC估计问题, 提出了一种改进的正交匹配追踪(Improved Orthogonal Matching Pursuit, IOMP)算法. 新算法运用迭代重加权最小二乘估计代替了正交匹配追踪(Orthogonal Matching Pursuit, OMP)算法中的最小二乘估计过程, 通过对样本进行迭代重加权, 逐步减小了异常样本的影响, 不断地修正了估计值, 在使用相同长度的训练序列时, 提高了估计的精度. 与传统的最小二乘估计算法相比, 新算法能够在获得相同估计效果的情况下, 显著减少所需训练序列的长度. 仿真结果验证了基于新算法的稀疏TWRC估计的有效性.     

小功率高转速蒸汽透平试验研究和优化

小功率高转速蒸汽透平试验研究和优化邵振麒（同济大学汽车工程系上海２０００９２）关键词：小蒸汽透平，效率，优化１前言回收能量和工业装置的余热及利用太阳能等新能源是节能和环保的重要措施，由此产生的机械能可供发电，气体增压等多种用途。在一些废热量不大且不宜...     

计及污垢影响的换热器热优化

本文利用熵产生数方法研究了气体和液体传热介质的顺流、逆流换热器的热力学完善性，结果表明，如给定冷、热流体的入口温度，在综合考虑传热、流动阻力和污垢的情况下，可用优化方法确定其它参数。     

Novel Image Optimization Method for Joint Photoacoustic Tomography

The distribution of speed of sound （SOS） in biomedical tissue and delay compensation （DC） have significant impact on the image quality of photoacoustic tomography （PAT）. When imaging human peripheral joints, using fixed SOS and DC can only ensure that the reconstructed images are focused in a limited depth range, whereas they are defoeused at other depths, which cause severe artifacts and blurring. In this work, a linear-DC based reconstruction approach is proposed to focus the whole PAT image region. It is proved by two in vivo experiments that, compared with traditional delay-and-sum back projection algorithms, the proposed method can effectively optimize the image quality of articular tissues in PAT.     

Design and optimization of with low weakly-coupled few-mode fiber nonlinearity

By investigating the influence of the difference of refractive index between core and cladding （nco - ncl）, normalized frequency （V） and core radius （α） on both the intramodal and intermodal nonlinear coefficients （NCs） respectively, we design a novel weakly-coupled four-mode fiber with low nonlinearity. In general, under the premise of ensuring the low NCs between two non-degenerate modes, this design can reduce the intermodal NCs （〈 0.5 W-l·km^-1） between two degenerate modes and optimizes the parameters of differential group delays （DGDs） and chromatic dispersion. The optimized few mode fiber （FMF） is eligible for transmission and mode de-multiplexing in the receiver.     

超导飞轮储能用永磁轴承参数优化

随着近年美、德、日等国研究小组的大容量高温超导飞轮储能系统(HTS FESS)样机的报道,具有控制简单、储能密度大、效率高、寿命长、应用范围广等优点的HTS FESS已经被广泛认可。综合主要研究小组的工作发现,采用高温超导磁悬浮轴承与永磁轴承配合的结构在保证飞轮转子轴向和径向都稳定的同时,具有成本低的优势。针对这种混合轴承布置方式,文中对超导飞轮储能用永磁轴承的承载能力进行了研究,通过有限元仿真分析提出了一种径向型永磁轴承的优化方案,相关结果可为后续样机研究提供一定的参考。     

Geometry optimization in planetary rotation stage for thickness uniformity of films on spherical substrates

We report the simulation results on the thickness uniformity of optical coatings deposited on spherical substrates by optimizing the geometric configuration parameters, such as tilting angle of the substrate holder and position of the evaporation source in a 1 000-mm-diameter planetary rotation stage （PRS）. We reveal that good film uniformity on convex spherical surfaces or flat substrates, as well as concave surfaces with weak to moderate curvatures can be obtained through appropriate tilting of the substrate holder. For 300-mm-diameter substrates with clear aperture to radius of curvature （CA/RoC） between 0.3 and 0.7, the achievable film uniformity is above 99%. The source position is optimized to achieve good film uniformity.     

谱有限元模拟正交各向异性黏弹性材料中导波传播特性

研究了导波在正交各向异性黏弹性复合板中传播的色散特性、波结构及功率流密度。基于二维平面运动方程,采用谱有限元方法得到了导波色散的特征方程。分析了正交各向异性黏弹性板中各向异性和黏性对能量速度和波结构的影响,以及基底对导波功率流密度的影响。数值研究结果表明:导波沿纤维方向传播的能量速度大,材料的黏性对速度影响较小,但会减小波结构的幅度;在高频时,基底的存在使两个基本模态的功率流密度分别集中到波导的上下表面,形成弱色散、高衰减及无色散、零衰减的表面波。数值模拟结果为导波用于复合材料定量无损检测和性能评价提供理论依据。      

Similarity Solutions for Generalized Variable Coefficients Zakharov-Kuznetsov Equation under Some Integrability Conditions

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.     

Design of dispersive multilayer with particle swarm optimization method

<正>We present a new and efficient method for the design of dispersive multilayer by employing a particle swarm optimization(PSO) technique.Its mathematical background is given and an adaptive PSO is realized with computer code.Two practical designing tasks are solved with this method,and the obtained results are competitive compared with other published structures.The adaptive PSO method demonstrates its merits of fast convergence and powerful global search ability,and could be used as a valuable tool for the optical thin film design.