考虑上部结构的桩筏基础非线性共同作用分析

当前虽然已有考虑桩筏非线性的设计,但仍无人在此基础上,考虑上部结构。因此考虑上部结构,进一步认识其与桩筏基础非线性共同作用机理,优化桩筏基础设计,具有重要的现实意义。本文以子结构法凝聚上部结构的荷载及刚度,以平面壳体单元模拟筏板,按有限层法模拟桩土之间的弹性相互作用,用广义剪切位移法模拟桩的非线性工作性状,建立了一种考虑上部结构共同作用的桩筏基础非线性分析方法,并编制了分析程序。通过实例分析,探讨了上部结构与桩筏基础非线性共同作用的机理,研究了合理布桩方式,探讨了以差异沉降为目标的优化设计的可能途径。     

Uniqueness in the water-wave problem for bodies intersecting the free surface at arbitrary anglesL'unicité du problème des ondes de surface pour les corps qui intersectent la surface libre sous des angles arbitraires

This Note deals with the linearized water-wave problem involving a surface-piercing cylinder in water of infinite depth. A solution to this problem is proved to be unique for all values of the radian frequency when the cylinder intersecting the free surface at arbitrary angles is subjected to certain geometric arrangements. To cite this article: N. Kuznetsov, C. R. Mecanique 332 (2004).     

Second-order hydroelastic analysis of a floating plate in multidirectional irregular waves

Based on an analysis of second-order hydrodynamic forces induced by coupling of first-order wave potentials, second-order hydroelastic equations are established and solved in the frequency domain. The responses of a very large floating structure in multidirectional irregular waves are studied. The characteristics of the difference and sum frequency coordinates are discussed in detail; peaks can be found at the difference and sum frequencies close to the wet resonant frequencies of each mode. We present and analyze the maximum vertical displacement of different points as well as the time history of the vertical displacements of selected points. The differences of the combined (the summation of the linear and non-linear responses) and linear displacements of the selected points are calculated. Our results demonstrate that non-linear fluid forces influence the total responses of the referenced floating structure.     

A hypersingular integral equation for the floating body problem

A new boundary integral equation formulation for the floating body problem, which is defined on a bounded domain and includes a hypersingular and a nonlocal part, is proved to satisfy a Gärding inequality. Under the assunlption of uniqueness it is shown, that an approximating sequence of related semidiscrete integral operators is uniformly bounded invertible.     

基于ARM和Zigbee的智能浮纹织造控制系统

针对纺织业中浮纹布的织造一直依赖纯机械控制的现状,为提高浮纹布织造的精度和效率,特设计了智能浮纹织造控制系统,通过上位机的工艺软件进行浮纹花色品种的设计,以U盘将多种浮纹工艺文件导入到浮纹织造控制系统里,以STM32处理器为核心根据浮纹工艺进行相关织造的电气控制。为了便于实时掌握浮纹布的产量并按订单及时进行品种的更换,系统以Zigbee技术实现数据的传输及命令的远程控制,避免了复杂的布线。经现场长时间运行,系统稳定可靠,织造速度可达250转/分以上,控制精度达到0.1mm,具有很好的应用价值。     

应用浮动基准法修正光谱光源漂移影响的模拟验证

近红外无创伤血糖检测目前面临的挑战主要是测量条件难以保证稳定、测量系统及被测对象自身的背景变化等问题,导致很难从背景变动的光谱中提取出糖浓度变化信息。经过多年的实验研究发现应用浮动基准参考测量法有望消除仪器漂移及被测对象自身背景变动的影响。但是浮动基准位置因人及测量部位不同而异,在不同的测量波长下其浮动基准点位置也不同,因此,欲在实验中验证浮动基准法的光谱修正效果需要测量出与入射光位置不同径向距离处的漫反射光强,然而在实际实验中位置精度很难保证。为此,研究了用模拟实验的方法验证多波长下浮动基准法对光源漂移所引起的光谱变化的修正效果,基于Monte Carlo模拟,分别采用浓度为5%和10%的Intralipid溶液作为被测样品,通过改变入射光子数模拟光源漂移的影响。得到模拟的光谱数据后,利用浮动基准法对其进行处理,并分别对浮动基准法修正前后的光谱数据进行偏最小二乘建模分析,将预测结果进行比较发现：两种浓度Intralipid溶液在存在光源漂移影响情况下修正后的模型预测精度预测均方根误差(RMSEP)相比于修正前分别减小了98.57%(5% Intralipid)和99.36%(10% Intralipid)。表明浮动基准法在消除光源漂移的影响方面效果明显。     

Coupling resonance of floating slab and supporting concrete box structure

This paper mainly investigates the effect of coupling resonance of floating slab and supporting short concrete box. The similarities and differences in vibration behaviors between long (30 m) and short (1.5 m) lengths of concrete box structures with the same cross-section were analyzed with finite element model (FEM). The results suggest that the major local modes for vibration and structure-borne sound radiation for long and short box structures are the same. A short concrete hollow box was constructed to verify the theoretical vibration results, and six combinations of floating slabs were installed on the box to identify the vibration and structure-borne sound control by experimental method. The resonance modes due to either concrete box or floating slab should degrade the vibration isolation performance of the floating system. There may be strong coupling between roll mode (rigid body rotation mode in the y-z plane) of the floating slab and local distortion mode of the short box structure and this can change the vibration resonance frequencies and amplify the vibration.     

Nonlinear water wave interaction with floating bodies in SPH

A weakly compressible SPH solver is presented for applications involving nonlinear interaction between water waves and floating bodies. A complete algorithm able to compute fully coupled viscous Fluid–Solid interactions is described. No slip boundary condition on the solid surface is enforced through a ghost–fluid technique and the global loads are evaluated through the momentum exchange between fluid and ghost particles. A dedicated algorithm is developed to manage the intersection between the free surface and the solid profile. An explicit synchronous algorithm is proposed for the full coupling between fluid and rigid bodies. Stability, convergence and conservation properties are tested on several freely floating test cases and a final validation of the full algorithm is performed for the interaction between a 2-D box and a wave packet.     

一种新型铅钐锡正极板栅合金

目前,铅钙锡合金已广泛用作阀控式铅酸蓄电池(VRLAB)的板栅材料.由于钙的存在,使铅钙锡合金阳极氧化时易形成高阻抗的阳极腐蚀层,并出现晶间腐蚀,电池循环充放电能力仍不理想.为克服铅钙锡合金作为正极板栅材料的不利因素.     

浮筏的主动吸振控制实验研究

浮筏在低频减振方面存在较大不足,而这恰是主动减振的优势.将两者相结合,研究了浮筏的主动吸振控制问题.研制了一种主动吸振器,建立了以DSP F2812为核心的控制系统;提出了符号LMS算法,与广泛使用的滤波x-LMS等算法相比,该算法不需要精确的模型信息;在此基础上设计了自适应前馈主动吸振控制律,并在浮筏实验平台上进行主动吸振控制实验.实验结果表明,通过主动吸振控制,浮筏的低频减振能力得到了显著的改善.