模拟电路单故障与多故障诊断的提升小波和RBF方法

为了更高效、更准确地诊断模拟电路的单故障和多故障,提出了提升小波和RBF神经网络相结合的方法。该方法用提升小波系数表征故障电路的特征,训练RBF神经网络,将训练好的神经网络作为分类器,对故障电路进行诊断。通过对比,提出的提升小波方法诊断效果明显优于传统小波,准确率达到99.2%,用时更长。结果表明,基于提升小波和RBF神经网络的模拟电路单故障与多故障诊断方法可以有效地提取故障电路的特征并准确快速地对故障进行分类。     

一种高增益多频带微带贴片单元的设计

设计了一种由圆、正八边形、矩形组合构成的微带贴片天线,其使用同轴线馈电。采用有限元法对所设计天线的电特性进行了仿真研究。同时也对天线在不同尺寸参数下的性能指标进行了对比分析。结果表明,天线兼具高增益和多频带的特性,在2.25~2.33GHz、3.51~3.7GHz、4.34~4.6GHz频带内,带内回波损耗全部小于-10d B,天线最高增益达到7.37d B,且天线的E面和H面辐射波束较好,半功率波束宽度约是60°;仿真结果证实了所设计的天线具有良好的性能指标。     

基于准正交编码的MIMO空间光通信技术研究

由于自由空间光通信严重受到大气湍流引起的光强起伏,光束漂移等问题对通信性能的影响,本文研究了大气信道特性并分析了空时分组编码方案,采用MIMO技术提高自由空间光通信系统的性能。基于MIMO技术下的准正交编码方案不仅可以增强信道的抗衰落能力而且可以提供一定的分集增益和编码增益。在Matlab平台下使用蒙特卡罗模拟方法,对系统的信道容量和误码率进行数值研究。仿真结果表明:采用MIMO技术能够提高信道容量,有效改善误码性能,而且分集数越高,通信质量越好。     

考虑安装错位的弧齿锥齿轮小轮齿面再设计

为保证弧齿锥齿轮副在实际工况下具有良好的齿面印痕与啮合状态,研究安装错位的识别技术以及错位条件下的齿面再设计技术.分析可导致相同齿面印痕的多种安装错位组合之间的关系;提取齿面印痕的数值特征,以两接触轨迹曲线的偏差和最小为目标函数,采用优化方法识别当量安装错位;基于局部综合法,根据当量安装错位重新设计小轮的齿面.以一对弧齿锥齿轮副为例,比较实际安装错位与当量安装错位作用下的小轮再设计齿面的差曲面,验证了该设计方法的正确性和有效性.     

集成Web Service在工作流管理系统中的应用

商业环境的快速变化对工作流技术提出更高的要求。为使工作流系统能适应不断变化的环境并能及时更新获取数据资源,提出将集成Web Service作为Agent(WSA)应用到多agent着色工作流网上,最后通过实例出示集成WSA在工作流系统中发挥的作用。     

Risk reduction in Sechahun iron ore deposit by geological boundary modification using multiple indicator Kriging

Uncertainty on the geological contacts and the block volumes of the models along boundaries is often a major part of the global uncertainty of reserve estimation.This work introduces a geostatistical technique that has been developed and tested in an iron ore deposit at Bafq mining district,in central Iran,and that,based on a probability criterion,helps to objectively model the geometry of this iron ore deposit.The main problem in reserve estimation of this ore body is its geometrical modeling and uncertainty in geological boundaries.This work deals with the geostatistical method of multiple indicator kriging,which is used to determine the real boundaries of ore body in different categories.This approach has potential to improve project performance and decrease operational risk.For this purpose,the ore body is separated into two categories including rich iron zone （w（Fe）〉45%） and poor iron zone （20%〈w（Fe）〈45%）.It significantly benefits to decrease the risk of reserve evaluation in the deposit.This case study also highlights the value of multiple indicator kriging as a tool for estimates the position of grade boundaries within the deposit.Comparison of the resultant probability maps with the real ore/waste contacts on the extracted levels shows that the first indicator model could separate the whole ore body （poor plus rich） from the waste zone by probability of more than 0.35,which concludes the total reserve of 53 million tons.The second indicator model applied to separate the rich and poor domains and the results show that the blocks with the estimated probability of equal to or more than 0.4 lay within the rich ore zone consisting of 15.8 million tons reserve.     

Across and along-wind responses of tall building

Most modern tall buildings using lighter construction materials are more flexible, which can lead to excessive wind-induced vibrations resulting in occupant discomfort and structural unsafety. It is necessary to predict and mitigate such wind-induced vibration at the preliminary design stage. Fluctuating across and along-wind loads acting on a tall building that could not be formulated theoretically were simulated numerically in the time domain using known across and along-wind load spectra. These simulated wind loads were used to estimate the across and along-wind responses of a tall building, which are less narrow-banded processes, based on the state space variable approach. The simulated across-wind response of root-mean-square value（0.0047） and that of KAREEM＇s（0.0040） and the simulated along-wind response of root-mean-square value（0.021） and that of SOLARI＇s（0.027） were compared. It is found that these are good approximations of closed form responses. Therefore, these numerically simulated across and along-wind loads can be used for across and along-wind responses estimation for the wind-resistant design of a tall building at the preliminary design stage.     

A novel contour design technique of super/hypersonic nozzle diverging section with sharing throat

A straightforward technique has been developed to quickly determine the wall contour of super/hypersonic nozzles working at multiply Mach number which share a common throat section.Mach number distribution along the centerline of the nozzle is specified in advance and divided into two sections,both of which are described by the b-spline function.The first section is shared by different exit Mach number nozzles.The nozzle contour is determined by the method of characteristics plus boundary layer correction.An example of this design method is employed to illustrate the technique with a computational fluid dynamics calculation.The simulation results indicate that desired Mach numbers are obtained at the nozzle exit,and the good flow quality is attained for different nozzles within δMa/Ma±0.56% in the flow core region.This technique improves the design precision of the converging-diverging nozzle,cancels waves completely,and achieves nozzles with multiple Mach number exiting which share a common throat section.     

基于多元智能理论的大学英语视听说自主学习模式研究

以多元智能理论为基础,介绍了沈阳建筑大学开展视听说自主学习模式试点教学的实践过程,并通过问卷和访谈调查了学习者对视听说自主学习的总体评价以及自主学习过程中存在的问题。研究表明,大部分学习者能够适应网络自主学习模式,并比较认可网络自主学习对英语学习的作用,但是视听说自主学习模式在教材、教学软件设计、学生之间、师生之间的交流与互动等方面还存在一些不足,学习者的积极性也有待提高。针对这些发现,本文提出了相应的教学建议。     

基于细节特征的高动态范围图像获取算法

为了解决真实场景的动态范围与数字图像的动态范围不匹配的问题,提出一种基于细节特征合成的高动态范围图像获取算法。该方法首先提取多幅不同曝光的低动态范围图像的细节特征,细节特征值越大表明所含细节信息越多,然后将归一化的特征值作为权重,合成多幅低动态范围图像,得到一幅高质量的合成图。实验表明,该算法能得到一幅含有较丰富细节特征、动态范围较广的图像,合成图像不需要色调映射就可以较好地在低动态范围显示器上直接显示。