电磁波层析成像反演射线路径的探讨

在电磁波 CT 测试中,发射、接收探头间的电磁波射线发射点、接收点位置决定反演后成果数据记录点的位置。为了确定电磁波仪发射、接收探头记录点位置,对探头分别进行钢管屏蔽实验,实验表明电磁波仪工作时电磁波能量主要集中在两探头的馈电点及天线末端间近似于平行四边形的区域内,不宜直接地简化为一条直线,将平行四边形区域简化为4条线段进行电磁波层析成像反演计算更符合实际情况。在此基础上,提出对电磁波 CT 数据采取4条射线路径单独反演后,再将4个结果按综合平均的方法进行处理。将此种处理方法应用于武汉地铁岩溶勘察数据处理中,并与目前基于1条射线的反演处理方法进行对比、验证。对比剖面反演数据结果表明,在采用同一反演软件条件下4条射线路径综合反演法精度优于1条射线反演法。     

Nonlinear optimized adaptive trajectory control of helicopter

This paper attempts to develop an optimized adaptive trajectory control system for helicopters based on the dynamic inversion method. This control algorithm is implemented by three time-scale separation architectures. Pseudo control hedging (PCH) is used to protect the adaptive element from actuator saturation nonlinearities and also from the inner-outer-loop interaction. In addition, to augment the attitude control system, two online adaptive architectures that employ a neural network are used. By tuning the neural network based on the system model, a better and faster learning will be achieved, but this is a frustrating and time consuming process. Due to complexity in accurate tuning of neural network, this paper introduces a non-dominated sorting genetic algorithm II (NSGA-II) for off-line optimization of the neural network. Thus, in the proposed method, the neural network can compensate model inversion error caused by the deficiency of full knowledge of helicopter dynamics more accurately. The effectiveness of proposed method is demonstrated by numerical simulations.     

Novel slotted stepped‐impedance resonator and its application to compact and high performance bandpass filter and diplexer design

By etching slots in the low‐impedance section of the conventional stepped‐impedance resonator, a novel slotted stepped‐impedance resonator (SSIR) is proposed. As two examples, a fourth‐order bandpass filter (BPF) operating at 1 GHz with a size of 0.078 λ_g × 0.062 λ_g and a miniaturized diplexer operating at 0.9/1.57 GHz with a size of 0.054 λ₀ × 0.086 λ₀ are designed based on the proposed SSIR. The fabricated BPF exhibits a high selectivity and a wide ?30 dB rejection upper stopband from 1.13 f₀ to 6.52 f₀, while the fabricated diplexer has up to ?60 dB output isolation. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Bed morphology, flow structure, and sediment transport at the outlet of Lake Huron and in the upper St. Clair River

An integrated multibeam echo sounder and acoustic Doppler current profiler field survey was conducted in July 2008 to investigate the morphodynamics of the St. Clair River at the outlet of Lake Huron. The principal morphological features of the upper St. Clair River included flow-transverse bedforms that appear weakly mobile, erosive bedforms in cohesive muds, thin non-cohesive veneers of weakly mobile sediment that cover an underlying cohesive (till or glacio-lacustrine) surface, and vegetation that covers the bed. The flow was characterized by acceleration as the banks constrict from Lake Huron into the St. Clair River, an approximately 1500-m long region of flow separation downstream from the Blue Water Bridge, and secondary flow connected to: i) channel curvature; ii) forcing of the flow by local bed topography, and iii) flow wakes in the lee side of ship wrecks. Nearshore, sand-sized, sediment from Lake Huron was capable of being transported into, and principally along, the banks of the upper St. Clair River by the measured flow. A comparison of bathymetric surveys conducted in 2007 and 2008 identifies that the gravel bed does undergo slow downstream movement, but that this movement does not appear to be generated by the mean flow, and could possibly be caused by ship-propeller-induced turbulence. The study results suggest that the measured mean flow and dredging within the channel have not produced major scour of the upper St. Clair River and that the recent fall in the level of Lake Huron is unlikely to have been caused by these mechanisms.     

水平井筒油水变质量分散流动压降研究

针对水平井筒中油水两相变质量流动,从理论和室内实验两个方面对分散流型下压降进行了研究,着重考虑壁面流体的流入对壁面摩阻系数的影响与不同流型间的转换。根据质量守恒、动量守恒方程,建立了水平井油水两相分散流型下压降预测模型。采用水、白油为实验介质,测量了水平管不同注入比、不同含水率下油水两相流压降值。实验结果分析表明,当含水率为40%时,油水发生反相,管道中流动压降最大,这和Brinkman/Roscoe混合黏度公式计算出的反相点一致。同时,压降模型预测结果与实验结果相比较平均相对误差为13.6%。     

基于MQP模型的电离图参数反演解析算法研究

针对现今普遍采用的偏导迭代电离图反演算法存在的求解依赖于初值选择的不足,给出了一种初值选择准则,保证了该算法的收敛性。同时,利用该准则,以及在对电离图虚高表达式进行合理近似的基础上,提出了一种新的电离图参数反演算法,该方法实现电离图参数反演的解析计算,较偏导迭代法计算量大大减少,更好满足工程实时性要求。     

基于依赖注入的移动终端应用开发

提出了一种基于依赖注入和控制反转提高移动终端应用移植性和重用性的解决方案,并在Spring框架上实现了手机拍照应用在不同平台间的移植.结果表明该方案取得了较好的效果,提高了移动终端应用软件的移植性和重用性.     

Output regulation of nonaffine nonlinear systems using singular perturbation theory

A control synthesis method for output regulation based on singular perturbation theory combined with inverting design is considered for a class of nonaffine nonlinear systems. The resulting control signal is defined as a solution to ＂fast＂ dynamics which inverts a series error model, whose state is exponentially stable. It is shown that, under sufficient conditions being consistent with the assumptions of singular perturbation theory, this problem is solvable with （ε） tracking error if and only if a set of first-order nonlinear partial differential equations are solvable. The control law can be easily constructed and the simulations show the feasibility and effectiveness of the controller.     

Partial state observers for linear systems with unknown inputs

We consider the problem of constructing partial state observers for discrete-time linear systems with unknown inputs. Specifically, for any given system, we develop a design procedure that characterizes the set of all linear functionals of the system state that can be reconstructed through a linear observer with a given delay. By treating the delay as a design parameter, we allow greater flexibility in estimating state functionals, and are able to obtain a procedure that directly produces the corresponding observer parameters. Our technique is also applicable to continuous-time systems by replacing delayed outputs with differentiated outputs.     

用地震速度反演重建声波曲线

由于受地震仪器观测精度及计算机处理能力的限制,地震反演的速度曲线所能达到的分辨率能力,不能满足勘探目标的需要（例如,１０ｍ以内的薄互层反演）。现设想地层沉积结构分形的特征,则可通过分形计算求得速度变化细节,尽可能地逼近实测的声波曲线。我们将这种由地震速度反演曲线进行分形计算的结果称为“重建的声波曲线”。通过对实际资料的试算表明,在声测资料较理想的情况下,重建的声波曲线与实测的声波测井曲线有很好的相