control with limited communication and message losses

We propose an H^∞ approach to a remote control problem where the communication is constrained due to the use of a shared channel. The controller employs a periodic time sequencing scheme for message transmissions from multiple sensors and to multiple actuators of the system. It further takes into account the information on the random message losses that occur in the channel. An exact characterization for controller synthesis is obtained and is stated in terms of linear matrix inequalities. Furthermore, an analysis on the loss probabilities of the messages to accomplish stabilization is carried out. The results are illustrated through a numerical example.     

Model of Frequency Analysis in the Visual Cortex and the Shape from Texture Problem

This paper addresses the question: at the level of cortical cells present in the primary area V1, is the information sufficient to extract the local perspective from the texture? Starting from a model of complex cells in visual area V1, we propose a biologically plausible algorithm for frequency analysis applied to the shape from texture problem. First, specific log-normal filters are designed in replacement of the classical Gabor filters because of their theoretical properties and of their biological plausibility. These filters are separable in frequency and orientation and they better sample the image spectrum which makes them appropriate for any pattern analysis technique. A method to estimate the local frequency in the image, which discards the need to choose the best local scale, is designed. Based on this frequency analysis model, a local decomposition of the image into patches leads to the estimation of the local frequency variation which is used to solve the problem of recovering the shape from the texture. From the analytical relation between the local frequency and the geometrical parameters, under perspective projection, it is possible to recover the orientation and the shape of the original image. The accuracy of the method is evaluated and discussed on different kind of textures, both regular and irregular, with planar and curved surfaces and also on natural scenes and psychophysical stimuli. It compares favorably to the best existing methods, with in addition, a low computational cost. The biological plausibility of the model is finally discussed.     

基于ARM9的嵌入式火灾预警系统的设计与实现①

设计了一种基于ARM9的嵌入式火灾预警系统,在ARM9上完成了视频图像的采集,火情识别和GPRS图像传输等功能的相应的系统构建和软件实现。改进的基于小波分析、混合高斯模型、RGB和HIS模型的火情识别算法能很好的排除干扰,准确判断火情。     

使用PT5.0模拟实现不同VLAN之间主机通讯

使用Packet Tracer V5.0（PT5.0）模拟软件可以在不影响教学质量的情况下,既节省了资金投入,又能满足正常的教学需要,提高了学习效率。介绍了PT5.0模拟软件的优点,三层交换机和路由器的区别,并以实例介绍了通过三层交换机和路由器来实现不同VLAN之间主机通讯的方法。     

一种新型铁路天窗分析与探讨

利用列车运行图,采用模拟分析的方法,分析计算了双线自动闭塞线路上V型天窗和X型天窗的在空间域上列车运行线集,由此得出了开设X型天窗比V型天窗使列车正常运行所要受的约束条件多。在此基础上提出了V—X混合型天窗,经计算表明,该维修天窗性能优于V型和X型天窗。     

Multistable electro‐optical modes in ferroelectric liquid crystals

Abstract— Multistable electro‐optical modes exist under certain conditions in ferroelectric liquid‐crystal (FLC) cells, which means that any light‐transmission level can be memorized after the driving voltage is switched off. The multistability is responsible for three new electro‐optical modes with different shapes of the gray‐scale curve that can be either S‐shaped (double or single dependent upon the applied‐voltage pulse sequence and boundary conditions) or V‐shaped dependent upon boundary conditions and FLC cell parameters. The origin of these modes will be described.     

Controller synthesis with guaranteed closed-loop phase constraints

In this paper, we present an analysis and synthesis approach for guaranteeing that the phase of a single-input, single-output closed-loop transfer function is contained in the interval [−α,α] for a given α>0 at all frequencies. Specifically, we first derive a sufficient condition involving a frequency domain inequality for guaranteeing a given phase constraint. Next, we use the Kalman–Yakubovich–Popov theorem to derive an equivalent time domain condition. In the case where V21-4TVJ07S-1-26/0?wchp=dGLbVlW-zSkzk" alt="View the MathML source" title="View the MathML source" align="absbottom" border="0" height=16 width="39"/>, we show that frequency and time domain sufficient conditions specialize to the positivity theorem. Furthermore, using linear matrix inequalities, we develop a controller synthesis approach for guaranteeing a phase constraint on the closed-loop transfer function. Finally, we extend this synthesis approach to address mixed gain and phase constraints on the closed-loop transfer function.     

A -based optimal finite-word-length controller design

A novel optimal Finite Word Length (FWL) controller design is proposed in the framework of μ theory. A computationally tractable close-loop stability measure with FWL implementation considerations of the controller is derived based on the μ theory, and the optimal FWL controller realizations are obtained by solving the resulting optimal FWL realization problem using linear matrix inequality techniques.     

基于单片机的温室自动控制系统

介绍一种基于单片机的温室温度自动控制系统。热敏电阻采集温室内的温度,单片机控制温度在液晶屏上实时显示,利用上位机进行实时监控,通过串行通信将采集到的数据送至上位机,应用系统自带的超级终端软件实现温室温度在上位机中的实时显示。     

传感器弱信号的放大应用电路

介绍了几种弱信号放大的基本方法和一些典型的应用电路。