在接收端实现流媒体同步控制的方法

本文提出了一种在RTP/RTCP协议的基础上实现流媒体同步控制的方法。该方法通过在接收端设置合适大小的缓冲区,实现媒体内的同步;通过以音频流为主媒体流,视频流为从媒体流,结合媒体流在接收端缓冲区的占用率,比较音频帧和视频帧的播放时间戳,对视频帧采取重复/丢弃方式来取得音视频媒体间的同步。实验表明,该种方法既保证单个媒体流的平滑播放,又能实现音视频的媒体间同步。     

Static solution on four-region spherial cavity expansion model in a pressure sensitive medium

Spherical cavity expansion model is often used to study the mechanic characteristics of pressure sensitive mediums. The most important one we do in the paper is that we construct a four-region model with σθ≠0 in damage region,which is different from what Satapathy did before and is more reasonable. By adopting this model,different constitutive equations were constructed by different method-elastic mechanics in elastic region,damage mechanics and fracture mechanics in damage region,and macro-micro mechanics theory in plastic region. Then using Durban's self-similarity assumption,the control differential equations with boundary conditions were established,and the static numerical solution of stress field and displacement field in the three different regions of elastic,damage and plastic area were discussed respectively. Results showed that this four-region model can describe precisely the mechanic characteristics of pressure sensitive mediums under initial pressure.     

Sensor placement for structural damage detection with modal data

A new method is presented for prioritizing sensor locations for structural health monitoring (SHM). In view of the needs of SHM and damage detection,sensor locations are optimized for the purpose of both sensitivity for local damages and independence of the target mode. However,the two different optimization criterions lead to an inconsistency of the optimal result. Considering the structural response changes that result from damage,the relationship between the structural response and damage is deduced from the structural motion equation by a quasi-analytical mode. Based on the harmony between damage identifiability and mode observability,an object function is set up,including the information of mode independence and damage sensitivity. Utilizing the technique of singular value decomposition,an interior algorithm for the optimum sensor placement is proposed with the multiple objective criterions of minimizing the condition number of coefficient matrix and maximizing the fisher information matrix. A numerical example shows that this approach can effectively avoid the contradiction between the two different optimization criterions. Comparing with the result of single object,the result of damage detection from the optical sensor locations is much more accurate.     

水泥在料配料控制系统设计

本文研究水泥生料配料控制系统的工艺流程,分析了系统的参数特点,在系统上位机进行主副随动的基础上,设计了物料配料控制器。分析和设计基于PID控制算法的水泥生料配料系统控制算法。实际工程应用表明,该系统具有很好的控制效果。     

基于价值链理论的预算管理模式研究

本文拟从价值链的视角出发,综合分析目前企业预算工作存在的问题,提出了基于价值链的预算管理编制方法,以期合理配置企业资源,从而实现企业价值最大化的目标。     

气压驱动式自动离合器控制技术研究

为了以较低成本实现AMT系统中离合器执行机构的气压驱动,在对离合器控制过程深入分析的基础上结合气动控制特点,提出了通过高速开关电磁阀以PWM方式驱动纯气动离合器执行机构的方法,及离合器参考模型自适应控制方法.通过多位驾驶员在不同道路条件和环境条件下的实车道路考核,验证了这种控制方法的可行性,研究结果同时表明:采用该方法的离合器执行机构价格低廉,为进一步实现产业化奠定了基础.     

淮水北调输水管道关键技术研究与应用

介绍了输水主管道的设计制造关键技术问题,通过比较备选管材特性,研究了选用的PCCP管道设计制作技术、空气阀布置设计和管道基座安装技术,对管道铺设方案、煤矿塌陷区的地基变形进行了分析。     

斜跨钢拱桥索梁锚固区主梁腹板加劲肋优选

为了进行斜跨钢拱桥索梁锚固区主梁腹板内侧加劲肋的优选,以张家口某斜跨拱桥为研究对象,通过比选确定正确的计算单元和合理的计算梁段长度,采用有限元分析软件Ansys对锚箱式索梁锚固结构进行研究,并全面分析构造细节如加劲肋形式对锚固区各方面的影响。经分析得到腹板内侧焊接对应于锚固板和承压板的斜向加劲肋时,螺栓容易布置;焊接竖向加劲肋时,施工方便,二者都能满足分散应力的要求。     

刚度矩阵的数值模拟方法

刚度矩阵是将一个受力物体划分为n个单元,各单元刚度矩阵集成为结构总刚度矩阵,实现了从单元刚度矩阵形成总体刚度矩阵的过程。本文应用单元刚度矩阵的方法,从工程实例出发,解决实际工程中的平面应力问题。     

居住建筑的生态技术

住宅建设随着城市化进程的加快必然造成消耗资源、影响环境的局面,运用生态建筑技术建造住宅是改善这一局面的有效措施.从生态技术角度对住宅建筑的环境、节能、材料使用、绿化、使用太阳能和减少污染等方面进行了有益的探索.