信号与系统中的matlab程序

在现行的理工科教学中,matlab的应用已经成为一个重要的内容。尤其在电子类的核心专业课信号与系统中,matlab的作用更加值得教师关注。文章就信号与系统这一课程中牵涉到的一些典型matlab程序,进行了注解和说明。试图在信号与系统和matlab的应用两方面找到了一个更为恰当的结合点,使学生和教师在专业知识和应用性工具方面,得到一个更好的处理方式。     

A non-commutative time-frequency tomography

The characterization of non-stationary signal requires joint time and frequency information. However, time and frequency are a pair of non-commuting variables that cannot constitute a joint probability density in the time-frequency plane. The time-frequency distributions have difficult interpretation problems arising from negative and complex values or spurious components. In this paper, we get time-frequency information from the marginal distributions in rotated directions in the time-frequency plane. The rigorous probability interpretation of the marginal distributions is without any ambiguities. This time-frequency transformation is similar to the computerized axial tomography (CT or CAT) and is applied to signal analysis and signal detection and reveals a lot of advantages especially in the signal detection of the low signal/noise (S/N).     

Weight measurement using image-based pose analysis

Image-based gait analysis as a means of biometric identification has attracted much research attention. Most of the existing methods focus on human identification, posture analysis and movement tracking. There have been few investigations on measuring the carried load based on the carrier＇s gait characteristics by automatic image processing. Nevertheless, this measurement is very useful in a number of applications, such as the study of the carried load on the postural development of children and adolescence. In this paper, we investigate how to automatically estimate the carried weight from a sequence of images. We present a method to extract human gait silhouette based on an observation that humans tend to minimize the energy during motion. We compute several angles of body leaning and determine the relationship of the carried weight, the leaning angles and the centroid location according to a human kinetic study. Our weight determination method has been verified successfully by experiments.     

脉冲等离子体气相合成氮化硼的研究

以Ｂ２Ｏ３粉扩ＮＨ３为原料，用脉冲等离子体反应器合成ＢＮ，所得产品经Ｘ射线衍射，红外光谱分析表明，产品中除含六方氮化硼外，还含有少量立方氮化硼，生产工艺简单。     

三层同轴液柱内的热毛细对流的近似解析解

1引言在微重力下用浮区法生长高质量、大体积单晶体是一种很有应用前景的方法，但热毛细对流所引起的诸如宏观不均匀性、生长条纹等缺陷严重限制了这一方法的应用。目前，人们试着用液封方法抑制热毛细对流。文献［1～3］分别对两层流体系统内的热毛细对流所作的研究表明：通过液封，被封层内的热毛细对流可以得到显著抑制。本文对圆柱三层流体系统内的热毛细对流进行研究，为热毛细对流规律的揭示以及进一步总结出其控制方法提供了理论数值依据。2控制方程和边界条件考虑长为L的互不溶混的三层轴对称同轴液柱，如图1所示，两端壁保持定温T…     

Quantum Key Distribution Using High-Dimensional Quantum Error-Avoiding Code

Using high-dimensional quantum error-avoiding code, we present two new quantum key distribution protocols over a collective noisy channel, i.e. six-photon and five-photon quantum error-avoiding codes. Compared with the previous protocols using four-photon and three-photon quantum error-avoiding code, the qubit efficiencies of the new protocols have increases of 16.67% and 5% respectively. In addition, the security of these protocols is analysed with a conclusion that the new protocols are much more secure than the four-photon and three-photon ones.     

ORACLE与SQL SERVER语言的比较

在不同的关系型数据库管理系统 (RDBMS)之间 ,存在很多差异 ,ORACLE和SQLSERVER都符合SQL 92标准的属性扩展 .从应用程序的开发人员的角度来看 ,ORACLE和SQLSERVER对数据进行管理方式没有太大的区别 ,ORACLE和SQLSERVER之间的内部差异却是十分明显 .本文研究了ORACLE和SQLSERVER的区别是为了实现ORACLE向SQLSERVER转换 .     

Mean Value on the Difference Between a Quadratic Residue and Its Inverse Modulo p

The main purpose of this paper is to use the generalized Bernoulli numbers, Gauss sums and the mean value theorems of Dirichlet L-functions between a quadratic residue and its inverse modulo p value formula. to study the asymptotic property of the difference （a prime）, and to give an interesting hybrid mean