用测量模态阻尼和振型的方法对复合材料薄平板进行无损质量检测

复合材料薄平板经热压制成后,都需要进行质量检测。本文探索用测量模态阻尼和振型的方法,对复合材料薄平板的制作质量进行无损检测,作为对其它昂贵的无损检测方法的补充。略述用振动方法进行无损检测的原理,测量薄平板阻尼的方法以及提高测量精度的措施。还讨论在测量薄平板阻尼时可能遇到的一些特殊问题(如非线性刚度、拍、模态密集等问题);以云母基复合材料薄平板作为例子,从测量其阻尼和振型的结果,对这种板的制作质量进行讨论。     

高山上的“圆石之谜”

奇特的石球1979年,新疆水文地质专家前往中蒙边境的北塔山深处开展地下水资源普查,在距离北塔山牧场东部几十千米处的山谷里作业时,惊奇地发现,在附近的山坡和断层中星罗棋布地分布着许多滚圆滚圆的石球。这些石球小的和乒乓球一般大,大的直径有1～2米,颇为壮观和迷离。绝大多数石球内部为同心圆;有的内部又有一坚硬的原石球,形态宛如鸡蛋中的蛋黄;有的内部却有远古芦木等植物化石;有的破开就只有单一的石球,看上去它们像是从地里长出来一般。     

On the Parsimony of Some Model-Selection Criteria in Econometric Modeling

ＯｎｔｈｅＰａｒｓｉｍｏｎｙｏｆＳｏｍｅＭｏｄｅｌ－ＳｅｌｅｃｔｉｏｎＣｒｉｔｅｒｉａｉｎＥｃｏｎｏｍｅｔｒｉｃＭｏｄｅｌｉｎｇＺＨＡＮＧＷｅｉ；ＬＩＵＢａｏ（ＩｎｓｔｉｔｕｔｅｏｆＳｙｓｔｅｍＥｎｇｉｎｅｅｒｉｎｇ（ＩＳＥ），ＴｉａｎｊｉｎＵｎｉｖ...     

A Study on the Design for Object-Oriented Adaptive Decision-Making Teams

1 .ＩＮＴＲＯＤＵＣＴＩＯＮＩｎＣ3Ｉｓｙｓｔｅｍｓ,ｒｅｃｅｉｖｉｎｇ ,ｔｒａｎｓｍｉｓｓｉｏｎ ,ｐｒｏｃｅｓｓｉｎｇａｎｄｄｉｓｐｌａｙｏｆｉｎｆｏｒｍａｔｉｏｎａｒｅｄｅｖｅｌｏｐｅｄｃｏｎｃｅｒｎｉｎｇｔｈｅｄｅ ｃｉｓｉｏｎｍａｋｉｎｇｏｆｃｏｍｍａｎｄｅｒｓ.Ｔｈｅｒｅｆｏｒｅ,ｔｈｅｍａｊｏｒｔａｓｋｏｆａＣ3Ｉｓｙｓｔｅｍｉｓｆｏｃｕｓｅｄｏｎｄｅｃｉｓｉｏｎｍａｋｉｎｇ.Ｗｉｔｈｔｈｅｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔｏｆｃｏｍｍｕｎｉｃａｔｉｏｎａｎｄｎｅｔｗｏｒｋ ,ｔｅａｍｄｅｃｉｓ…     

Design and implementation of 2DOF spherical inverted pendulum

1.INTRODUCTION Theinvertedpendulumsystemisaclassicalbench markfortheeducationandresearchintheautomation andmechanicalengineeringfield.Manyeducatorsfo cusontheinvertedpendulumcontrolsystembecause theexperimentsexhibittheadvantageandvalidityof moderncontroltheoryveryintuitively.Researchers alsohopetoverifynewalgorithmsonthesystem. Thebasicobjectiveoftheinverted pendulumsystem iskeepingthebalanceofthependulumatthe‘invert ed’status[1～3].Wehavecomparedtheperformance ofthreemoderncontrolm…     

PRELIMINARY STUDY ON RETRO-REFLECTIVE COATED PAPER BASED ON MICROGLASS BEADS

INTRODUCTIONThe micro-glass bead[1-2] is a new kind of silicate material, with good properties of chemical stability, mechanical strength as well as electro-resistance. When its diameter is below 0.08mm and the reflective index is in the range of 1.9~2.1, retro-reflective characteristics can be achieved. When a beam of ray from any direction irradiates the surface of the micro-glass beads, it can be converged at the special reflective layer consisted of focuses of micro-glass beads, owing …     

使人难以置信的视觉移植

我们眼球的后部整齐地排列着10亿个特殊的光敏感神经细胞,阏读这些文字需要其中四分之一以上的细胞协同参与.反映在组构精密被称为视网膜的神经组织上,由这些字母组成明暗不同的各种文字被转     

STABILITY CRITERIA FOR A CLASS OF UNCERTAINSYSTEMS WITH TIME—DELAY

Some stability criteria are obtained for a class of uncertain systems with time-delay usingLyapunov functional and analytic techniques. It is easy to check the criteria by making use of theboundedness of the uncertainties.     

Researching on quadrature conversion structures For an UWB demonstrative receiver

1. INTRODUCTION As the development of technologies of digital signal processing and integrated circuits, the structure of wireless communication system has been improved. Many schemes for software defined radio (SDR) systems have been developed since 1995, and they can be divided into five tiers of solutions according to their developing history and their definitions[1]. The five tiers are conventional hardware-implemented scheme; software-controlled radio scheme; SDR, that implements m…