THMR-V平台上的智能交通监控系统设计与实现

随着我国经济水平增长,汽车的占有率不断增高,尤其是家用汽车已经成为当今最为普遍的交通工具。为此,提高我国交通管制手段,提高管理监控能力是当前我国交通事业发展中非常重要的一部分。设计出一种智能交通系统,依靠THMR-V室外移动机器人及视觉临场遥感系统,配合计算机智能分析技术以及信息处理和传递技术为基础,对当前的交通环境实现智能监控和管理。对该系统进行实际应用测试,并且做出分析与结果。     

利用反向投影的flash场景自适应视频编码算法

针对闪光造成的光照变化会导致视频帧之间巨大的强度差异问题,提出利用反向投影的flash场景自适应视频编码算法。根据直方图差异提取闪光和非闪光帧,相应地为每个帧分配适当的编码类型,并在加权预测(WP)参数集确定中采用运动向量导数,通过反向投影保证flash场景的全局一致性。实验结果表明,相比其他几种加权预测算法,本文算法在峰值信噪比(PSNR)及计算复杂度方面获得了更加优越的编码性能。     

自动驾驶技术进展与运营商未来信息服务架构演进

人工智能概念的提出迄今已经60余年,随着物联网、大数据技术的发展,越来越多的人工智能应用逐步实现,自动驾驶技术是目前最引人瞩目的人工智能技术集成应用。首先研究了自动驾驶技术研发进展;其次分析了自动驾驶的关键技术;然后分析了自动驾驶与运营商未来信息服务架构之间的关系;最后给出了未来运营商以人工智能技术应用为核心的信息服务架构的技术切入点。     

动载荷的识别方法

大多数情况下, 作用在工程结构上的动载荷, 如高性能战斗机在大攻角机动飞行时作用在垂尾结构上的抖振载荷, 是无法直接测量的, 只能通过测试结构在动载荷作用下的动态响应来识别出结构的动载荷. 首先阐述了动载荷识别的基本原理, 然后根据结构模型的特点, 将动载荷识别方法分为确定性结构的动载荷识别方法和不确定性结构的动载荷识别两大类, 对近些年国内外学者在这两方面的研究进展进行述评, 最后针对目前动载荷识别方法研究中所存在的问题, 提出有待深入探讨的课题.      

High-order parabolic beam approximation for aero-optics

The parabolic beam equations are solved using high-order compact differences for the Laplacians and Runge–Kutta integration along the beam path. The solution method is verified by comparison to analytical solutions for apertured beams and both constant and complex index of refraction. An adaptive 4th-order Runge–Kutta using an embedded 2nd-order method is presented that has demonstrated itself to be very robust. For apertured beams, the results show that the method fails to capture near aperture effects due to a violation of the paraxial approximation in that region. Initial results indicate that the problem appears to be correctable by successive approximations. A preliminary assessment of the effect of turbulent scales is undertaken using high-order Lagrangian interpolation. The results show that while high fidelity methods are necessary to accurately capture the large scale flow structure, the method may not require the same level of fidelity in sampling the density for the index of refraction. The solution is used to calculate a phase difference that is directly compared with that commonly calculated via the optical path difference. Propagation through a supersonic boundary layer shows that for longer wavelengths, the traditional method to calculate the optical path is less accurate than for shorter wavelengths. While unlikely to supplant more traditional methods for most aero-optics applications, the current method can be used to give a quantitative assessment of the other methods as well as being amenable to the addition of more physics.     

A multilevel Cartesian non-uniform grid time domain algorithm

A multilevel Cartesian non-uniform grid time domain algorithm (CNGTDA) is introduced to rapidly compute transient wave fields radiated by time dependent three-dimensional source constellations. CNGTDA leverages the observation that transient wave fields generated by temporally bandlimited and spatially confined source constellations can be recovered via interpolation from appropriately delay- and amplitude-compensated field samples. This property is used in conjunction with a multilevel scheme, in which the computational domain is hierarchically decomposed into subdomains with sparse non-uniform grids used to obtain the fields. For both surface and volumetric source distributions, the computational cost of CNGTDA to compute the transient field at N_s observation locations from N_s collocated sources for N_t discrete time instances scales as O(N_tN_slogN_s) and O(N_tN_slog²N_s) in the low- and high-frequency regimes, respectively. Coupled with marching-on-in-time (MOT) time domain integral equations, CNGTDA can facilitate efficient analysis of large scale time domain electromagnetic and acoustic problems.     

A comparative study of iterative solutions to linear systems arising in quantum mechanics

This study is mainly focused on iterative solutions with simple diagonal preconditioning to two complex-valued nonsymmetric systems of linear equations arising from a computational chemistry model problem proposed by Sherry Li of NERSC. Numerical experiments show the feasibility of iterative methods to some extent when applied to the problems and reveal the competitiveness of our recently proposed Lanczos biconjugate A-orthonormalization methods to other classic and popular iterative methods. By the way, experiment results also indicate that application specific preconditioners may be mandatory and required for accelerating convergence.     

Effect of nitrogen concentration on the electronic and vibrational properties of zinc-blende InNxP1-x(x < 0.01)

Taking into account the recent advances in the epitaxial growth of single-crystal InN leading to a drastic re-evaluation of its fundamental energy band gap, we have studied the electronic properties of InN_xP_1-x (x < 0.01) ternary alloy. Using the empirical pseudopotential method under the virtual crystal approximation, combined with the Harrison bond orbital model, the band gap at Γ, X and L points, the effective masses of the Γ valley and the electronic charge densities are calculated as a function of nitrogen composition. The fitted expressions of the energy band gaps indicate that the bowing parameter at Γ reached a broad value for very low nitrogen incorporation ( ). Furthermore, the band gap at Γ point decreases drastically with increasing nitrogen composition up to 1%. The elastic constants and the optical phonon frequencies are also reported. Our theoretical results provide a good agreement with the available data.     

Molecular-dynamics simulations with explicit hydrodynamics II: On the collision of polymers with molecular obstacles

We present a study of the dynamics of single polymers colliding with molecular obstacles using Molecular-dynamics simulations. In concert with these simulations we present a generalized polymer-obstacle collision model which is applicable to a number of collision scenarios. The work focusses on three specific problems: i) a polymer driven by an external force colliding with a fixed microscopic post; ii) a polymer driven by a (plug-like) fluid flow colliding with a fixed microscopic post; and iii) a polymer driven by an external force colliding with a free polymer. In all three cases, we present a study of the length-dependent dynamics of the polymers involved. The simulation results are compared with calculations based on our generalized collision model. The generalized model yields analytical results in the first two instances (cases i) and ii)), while in the polymer-polymer collision example (case iii)) we obtain a series solution for the system dynamics. For the case of a polymer-polymer collision we find that a distinct V-shaped state exists as seen in experimental systems, though normally associated with collisions with multiple polymers. We suggest that this V-shaped state occurs due to an effective hydrodynamic counter flow generated by a net translational motion of the two-chain system.     

基于群体智能的自组织运动控制综述

文中阐述了群体、群集、群体智能、群体控制以及群体系统等相关概念,综述了基于群体智能的自组织运动控制的相关研究工作和研究内容,包括群体控制系统模型的发展历程、群体控制中的各种群集控制策略和控制算法、群体控制系统的系统行为表现以及基于群体控制扩展的各类智能优化算法。最后文中提出了群体自组织运动控制研究的发展趋势。