内激励型振荡衰减流作用下输流管道动力不稳定分析

振荡衰减流作为一种内激励形式,对输流管道的稳定性和共振特性将产生影响。基于输流管道横向振动运动微分方程,引入指数衰减函数模拟水锤发生时流速呈现的振荡衰减特性,推导得到内激励型振荡衰减流作用下输流管道动力不稳定区域的表达式。在无衰减周期脉动流激励条件下,计算得到两种不同支撑输流管道的不稳定区域,与前人数值研究结果吻合良好。同时将引入的流速表达式与水锤条件下黏弹性输流管道模型计算得到的流速时程进行对比,表明所提出的流速表达式能较好地反映水锤激励下输流管道内水流的双向衰减特性。进一步分析了衰减特征参数对两端简支输流管道不稳定区域的影响,结果表明,内激励型振荡衰减流对于输流管道横向振动的影响不容忽视,当流速衰减系数b增加,不稳定区域向下偏移,且初始流速u 0增大,偏移现象越明显;同时随着时间τ的推移和衰减系数b的增加,流速衰减越快,不稳定区域闭合加快,当管道内流速衰减至0时,水锤过程结束,管道不稳定区域消失。     

径流式增压器涡轮非设计工况性能的分析和计算

本文对径流式增压器涡轮的变工况特性进行了分析,并就其计算中的某些损失模型进行了探讨。在此基础上编制了电算程序,实例计算表明其结果的精度符合实用要求。     

一种基于边缘生长的灰度和彩色图象分割方法

边缘检测可以快速准确地提供区域分割的边缘点,是图象处理的一个重要领域。但由于边缘点不连续和难以把存在大量碎边缘点的高细节区提取出来这两个原因,而不能直接实现完整意义上的图象分割。为此提出用边缘生长的方法来解决不连续的边缘点链接问题和通过找出高细节区周围的区域,以便间接地将高细节区围成一个区域。该算法是边缘检测的后续处理,适合于多种应用目的,同时还可以嵌入到其它利用边缘信息的分割算法中。     

Electroless Ni-Co-P Coating of Cenospheres Using Ag(NH_3)_2~+ Activator

FLY ASH CENOSPHERES are primarily a by-productin power generation plants.Research is in progress toeffectively use this by-product to produce new usableand profitable materials as they pose major disposaland environmental problems.Fly ash cenospheres areunique,property stable,non-toxic,non-metallic hollowmicro-particles.Due to the unique hollow structure andphysical mechanics properties,Cu^Ag and other metalsare often coated on cenospheres to produce lightweightmetal matrix composites,w…     

联系测量在某矿山的应用

某矿山330第一运输平硐自2005年投入使用后已有20年的历史,巷道顶板的控制点已基本废弃或丢失,无法满足巷道中各溜井的生产改造工程的工作需要。当进行实地测量作业时,由330第一运输平硐口引入控制点,水平距离可达2～3km,实测过程工作量大,也易导致精度无法满足设计需求的情况。2022年8月,根据矿山生产建设需要,通过一井定向作业的方式,重新将地表坐标系统导入330m第一运输平硐,为后续的生产作业提供了方便。     

MICROSTRUCTURE AND COMPRESSIVE PROPERTIES OF NiAl-TiB_2 PARTICULATE COMPOSITES

Ni-50at.%Al matrix composites containing 0 to 20v.% TiB_2 particles have beensuccessfully fabricated by HPES technique. The results show that the Vickers hardness atroom temperature and the compressive yield strength from room temperature to 1000℃ ofthe composites increase with increasing volume.fraction of the strengthening phase. Espec-ially, the yield strength of NiAl-20TiB_2 was approximately twice as high as that ofunreinforced NiAl. The ductility of the composites at room temperature is also superior tothe monolithic NiAl.     

PHASE TRANSFORMATION INDUCED BY DEFORMATION IN TiAl(Cr) INTERMETALLICS AT ROOM TEMPERATURE

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A Universal Analytic Potential-Energy Function Based on a Phase Factor

Using a field equation with a phase factor, a universal analytic potential-energy function applied to the interactions between diatoms or molecules is derived, and five kinds of potential curves of common shapes are obtained adjusting the phase factors. The linear thermal expansion coefficients and Young‘s moduli of eleven kinds of fuce-centered cubic (fcc) metals - Al, Cu, Ag, etc. Are calculated using the potential-energy function; the computational results are quite consistent with experimental values. Moreover, an analytic relation between the linear thermal expansion coefficients and Young‘s moduli of fcc metals is given using the potential-energy function. Finally, the force constants of fifty-five kinds of diatomic moleculars with low excitation state are computed using this theory, and they are quite consistent with RKR (Rydberg-Klein-Rees) experimental values.     

Research on Strategic Cooperation Between China Post and Telecoms

1IntroductionFacing the rapid development of social economy andscience technology China Post needs wide cooperation a-mong industries to gain competitive advantage and de-velopment space , which appeals the leading-edge tele-comindustry to become its partner .In some fields Chi-na Post and the Telecoms have launched business coop-eration which stays onlowlevel ,so for China Post it isurgent to establish relationship to the Telecoms onstrategiclevel presently,which will build win-winsitua-ti…