Adaptive fault-tolerant control for a class of flexible air-breathing hypersonic vehicles

In this paper, a novel adaptive fault-tolerant control (FTC) scheme is proposed for a class of flexible air-breathing hypersonic vehicles with unknown inertial and aerodynamic parameters and even input constraints. The fault model under consideration covers the case that all actuators suffer from unknown time-varying faults. In the controller design and stability analysis, we introduce new Lyapunov functions, some differentiable auxiliary functions, a bound estimation approach, and a Nussbaum function, which help us successfully circumvent the obstacle caused by the faults, input constraints, and flexible modes. In addition to higher reliability, the proposed scheme is able to ensure that all closed-loop signals are globally uniformly bounded and to steer the tracking errors of altitude and velocity into predefined arbitrarily small residual sets. As a result, the tracking accuracy can be designated in advance. Simulation results illustrate the effectiveness of the proposed scheme.     

Testing Transverse Sensitivity of Linear Single-Axis Pendulous Accelerometer with Double Turntable Centrifuge

Current ISO standard methods for testing transverse sensitivity of accelerometers are vibration-based. They have difficulties in producing low-frequency vibration for various reasons. This paper introduces a double turntable centrifuge (DTC) to test the accelerometer transverse sensitivity at low frequencies (from 0.01 to 10 Hz). The proposed method can avoid limitations of traditional vibration-based schemes for transverse sensitivity test. In this paper, a theoretical analysis of the method is followed by a presentation of the experimental set-up, and the measurement procedure of a linear single-axis pendulous accelerometer. According to the theoretical analysis and experimental results, it is practicable to test the low-frequency transverse sensitivity with a DTC. The method proposed here can test accelerometer transverse sensitivity at low-frequency with large amplitudes (up to 700 m/s²), and directly measure the angle of the transverse sensitivity with high resolution. It can be a supplement to the standard methods for testing accelerometer transverse sensitivity at low-frequency.     

加强计量信息化建设,提高企业计量管理水平

网络化的计量管理信息系统在技术上的实用性和维护性上面都有其可靠性,对计量管理工作采用信息化管理可以真正实现完全意义上的信息共享,使我们管理的计量装置、计量器具准确可靠的运行。     

新一代液晶显示系统设计与实现

随着时代的演进和科技的进步,液晶显示已经在现代科技产品中得到广泛应用,为了提高液晶显示系统在带有电容触摸技术的现代电子产品中开发与应用,文章中采用新一代8位STM8S208系列MCU和ET-12864F液晶显示模块,设计了一种新型的液晶显示系统;同时介绍了STM8S208单片机的优越性和ET-12864F液晶显示模块的具体操作方法,并给出了单片机STM8S208与液晶显示模块ET-12864F构建的硬件接口电路和程序设计;经实践应用,该液晶显示系统应用开发成本低,效率高具有较好的项目应用参考价值。     

基于二阶梯度的图像增强算法研究

针对PCB图像的特点对图像进行增强处理,使得图像的边缘更加突出,灰度的对比度增加,同时滤除靠近边缘的噪声,为后续图像分割时更有效的选取阈值打下良好基础。使用二阶梯度算子获得图像的增强效果,实验表明,不仅解决了边缘附近噪声去除问题,而且有效地突出了边缘信息,图像的黑白对比分明,尤其是目标图像靠近边缘部分灰度值明显高于其他的非边缘区域。     

Synchronization of complex dynamical networks under recoverable attacks

In this paper, the synchronization of complex dynamical networks (CDNs) under ‘successful’ but recoverable attacks is studied by utilizing the framework of switching systems. ‘Successful’ attacks refer to a class of attacks that break a network into a group of isolated clusters. Recoverable attacks refer to a class of attacks that the network can recover from after a period of time. To facilitate the investigation of the synchronization of a CDN under ‘successful’ but recoverable attacks, the attack frequency and the average recovering time are introduced. By using a piecewise Lyapunov function, the upper bounds of the attack frequency and the average recovering time are obtained to ensure that the whole network can achieve global synchronization under attacks.     

嵌入式系统芯片的软硬件协同仿真环境设计

针对嵌入式系统芯片SoC开发验证阶段的需求,介绍了一种通用的SoC软硬件协同仿真平台。软件仿真由C／C＋＋和汇编语言编写,硬件仿真基于VMM验证方法学所搭建,SoC设计代码由RTL代码编写而成。将SoC设计代码中的ARM由DSM模型替代,通过VCS编译器将软硬件协同起来进行信息交互,实现一种速度快、真实性高、调试方便的...     

Optimized element positions for prescribed radar cross section pattern of linear dipole arrays

Approximate closed‐form expression is derived for the scattering from dipole arrays based on the equivalent circuit theory. Then, a method is proposed for synthesis of dipole arrays to produce desired scattering pattern using genetic algorithm (GA). In the synthesis method, the element positions in an array are considered as the optimization parameter and the derived expression is used to evaluate the fitness function of GA. To assess the validity and efficiency of the proposed method, several linear dipole arrays are designed to obtain scattering pattern with low sidelobe level (SLL). A good agreement between the patterns calculated using the expression and simulated by FEKO validates the accuracy of the presented expression. In addition, the numerical results show that the maximum SLL of the scattering pattern is considerably reduced by optimization. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.