Dynamic modeling of a hose-drogue aerial refueling system and integral sliding mode backstepping control for the hose whipping phenomenon

Dynamic modeling of a hose-drogue aerial refueling system（HDARS） and an integral sliding mode backstepping controller design for the hose whipping phenomenon（HWP） during probe-drogue coupling are studied. Firstly, a dynamic model of the variable-length hose-drogue assembly is built for the sake of exploiting suppression methods for the whipping phenomenon.Based on the lumped parameter method, the hose is modeled by a series of variable-length links connected with frictionless joints. A set of iterative equations of the hose＇s three-dimensional motion is derived subject to hose reeling in/out, tanker motion, gravity, and aerodynamic loads accounting for the effects of steady wind, atmospheric turbulence, and tanker wake. Secondly,relying on a permanent magnet synchronous motor and high-precision position sensors, a new active control strategy for the HWP on the basis of the relative position between the tanker and the receiver is proposed. Considering the strict-feedback configuration of the permanent magnet synchronous motor, a rotor position control law based on the backstepping method is designed to insure global stability. An integral of the rotor position error and an exponential sliding mode reaching law of the current errors are applied to enhance control accuracy and robustness. Finally,the simulation results show the effectiveness of the proposed model and control laws.

Research of Springing and Whipping Influence on Ultra-Large Containerships' Fatigue Analysis

Rules of Classification Societies all around the world have made changes on design wave loads' value and fatigue influence factor modification due to the influence of springing and whipping on ultra-large containerships.The paper firstly introduced 3-D linear hydroelastic theory in frequency domain and 3-D nonlinear hydroelastic theory in time domain, considering large amplitude motion nonlinearity and slamming force due to the severe relative motion between ship hull and wave. Then the spectrum analysis method and time domain statistical analysis method were introduced, which can make fatigue analysis under a series of standard steps in frequency and time domain, respectively. Finally, discussions on the influence factor of springing and whipping on fatigue damages of 8500 TEU and 10000 TEU containerships with different loading states were made. The fatigue assessment of different position on the midship section was done on the basis of nominal stress. The fatigue damage due to whipping can be the same as the fatigue damage due to springing and even sometimes can be larger than the springing damage. Besides, some suggestions on calculating load case selection were made to minimize the quantity of work in frequency and time domain. Thus, tools for fatigue influence factor modification were provided to meet the demand of IACS-UR.

利用Whip!Viewer建立网上地图资料检索系统

针对城市勘测单位外业队在资料中心查数据、调数据、分发地图工作比较繁琐,以Whip!Viewer设计一套网上地图资料检索系统方案,实现地图资料的高效、准确获取。

Effect of Post-Added Water Amount on Pre-Concentrated Bark Foaming Materials by Mechanical Stirring

In this study,pre-concentrated bark,furfuryl alcohol and other biomass raw materials were used to prepare foaming materials by high-speed mechanical stirring without using a foaming agent.We investigated the effect of the postadded water amount on the properties of foaming materials.In particular,we determined basic physical properties of these materials,including the limiting oxygen index(LOI),porosity,thermal conductivity,thermogravimetric analysis,pore size distribution,and microstructure.The results of scanning electron microscopy(SEM)indicated that the pore size distribution was uniform and the pore size increased with increasing water volume.Thermogravimetric analysis(TG/DTG)showed that when the temperature reached 410°C,the foam was easily decomposed,the final residual mass was only 2.8%,and water addition had little effect on it.Moreover,the amount of post-added water is 5–30 g,the density and compression strength of the foamed materials gradually decreased,while the degree of pulverization increased.LOI ranged from 26.1%to 30.79%,and porosity ranged from 81%to 83%.The change in water volume greatly affected the foam’s performance,the performance of foamed material deteriorated as the amount of added water increased,but the effect on thermal conductivity was not very obvious.The highest thermal conductivity was only 0.0179 W/(m·K),still providing excellent thermal insulation.

基于WWW浏览器浏览工程图形的方法

在Internet上 ,WWW浏览器不能直接浏览工程矢量图形 ,但通过安装WHIP !插件 ,可克服这一不足。文章详细介绍了WHIP !

How does a woodpecker work? An impact dynamics approach

To understand how a woodpecker is able accelerate its head to such a high velocity in a short amount of time,a multi-rigid-segment model of a woodpecker＇s body is established in this study.Based on the skeletal specimen of the woodpecker and several videos of woodpeckers pecking,the parameters of a three-degree-of-freedom system are determined.The high velocity of the head is found to be the result of a whipping effect,which could be affected by muscle torque and tendon stiffness.The mechanism of whipping is analyzed by comparing the response of a hinged rod to that of a rigid rod.Depending on the parameters,the dynamic behavior of a hinged rod is classified into three response modes.Of these,a high free-end velocity could be achieved in mode II.The model is then generalized to a multihinge condition,and the free-end velocity is found to increase with hinge number,which explains the high free-end velocity resulting from whipping.Furthermore,the effects of some other factors,such as damping and mass distribution,on the velocity are also discussed.

基于Web技术的旱作农业机械工程图形管理系统

为了管理大量的旱作农业机械工程图纸,借助企业的Intranet, 开发了一个综合的Web版管理系统,促进企业信息化。系统利用Whip控件和ASP技术,解决了存储于数据库中的工程图形浏览问题。

基于Internet的制造业CAD信息系统设计

阐述了基于Internet的信息系统的优越性,给出了基于Internet的制造业CAD信息系统的结构,指出了建设基于Internet的信息系统的关键技术问题以及CAD信息系统应具备的功能。

Numerical Computation of Motions and Structural Loads for Large Containership using 3D Rankine Panel Method

In this paper, we present the results of our numerical seakeeping analyses of a 6750-TEU containership, which were subjected to the benchmark test of the 2 nd ITTC–ISSC Joint Workshop held in 2014. We performed the seakeeping analyses using three different methods based on a 3D Rankine panel method, including 1) a rigid-body solver, 2) a flexible-body solver using a beam model, and 3) a flexible-body solver using the eigenvectors of a 3D Finite Element Model(FEM). The flexible-body solvers adopt a fully coupled approach between the fluid and structure. We consider the nonlinear Froude–Krylov and restoring forces using a weakly nonlinear approach. In addition, we calculate the slamming loads on the bow flare and stern using a 2D generalized Wagner model. We compare the numerical and experimental results in terms of the linear response, the time series of the nonlinear response, and the longitudinal distribution of the sagging and hogging moments. The flexible-body solvers show good agreement with the experimental model with respect to both the linear and nonlinear results, including the high-frequency oscillations due to springing and whipping vibrations. The rigid-body solver gives similar results except for the springing and whipping.

工程制图网上练习课件的研究与开发

针对工程制图课后练习的必要性 ,将典型习题及其答案放到网上 ,据此开发出工程制图网上练习课件。通过Whip插件可使网页中的绘图题随时下载到AutoCAD绘图环境中来完成练习。利用Flash制作的二维动画可以形象地向学生演示具体解题过程。另外给出答案的同时附加三维立体模型 ,可以让学生一目了然。素材的合成通过Dreamweaver实现。

Local Impedance Spectroscopy： A Potential Tool to Characterize the Evolution of Emulsions and Foams

The potential of local impedance spectroscopy （IS） to access changes in emulsions and foams has been investigated. As test systems we used the separation of a simple oil/vinegar mixture as well as the whipping process of dairy cream. For the latter, IS data were compared to particle size distribution （PSD） measurements. Our measurements show that local IS is indeed a valuable tool to locally study processes in emulsion. On one hand, it seems to be very sensitive to small water quantities in oil thus being a suitable method for process control in water removing processes. On the other hand, concerning fat foams, it seems to be able to detect the evolution of foam structures. Both examples show that local IS could be a helpful tool for process control.

AutoCAD网上图形的实现方法

通过对网上图形格式的分析探讨了利用WHIP插件和网络制作工具将CAD图形放 在网上的方法，并给出了具体的实施步骤。

ON-LINE ELIMINATION OF OIL WHIP

A new method to eliminate the oil whip online is put forward by use ofpassive electromagnetic damper. The damper works contactless and with DC current. Neither sensor norclosed loop control is needed. The dynamic equations of rotor-bearing system are built up bycombining d'Alemdert principle with Rize way, and the nonlinear oil film forces based on unsteadyshort bearing model are coupled to system. Such nonlinear equations are numerically solved byNewmark integration method. The calculated results show that the bifurcation behavior of the systemcan be. changed and the oil whip of the rotor may be well damped by external damping. Thebifurcation diagrams also show that the subharmonic vibration amplitude decreases in motion and thespeed at which the system losses its stability increases obviously by exerting external damping.Then experiments are carried out to demonstrate this phenomenon. It is observed that the complextrajectories of the journal motion are disappeared and the rotor-bearing system became stable whenthe power of passive electromagnetic damper is turned on. The experiments have good repeatability.

Nonlinear Vibration Induced by the Water-film Whirl and Whip in a Sliding Bearing Rotor System

Many industrial applications and experiments have shown that sliding bearings often experience fluid film whip due to nonlinear fluid film forces which can cause rotor-stator rub-impact failures. The oil-film whips have attracted many studies while the water-film whips in the water lubricated sliding bearing have been little researched with the mechanism still an open problem. The dynamic fluid film forces in a water sliding bearing are investigated numerically with rotational, whirling and squeezing motions of the journal using a nonlinear model to identify the relationships between the three motions. Rotor speed-up and slow-down experiments are then conducted with the rotor system supported by a water lubricated sliding bearing to induce the water-film whirl/whip and verify the relationship. The experimental results show that the vibrations of the journal alternated between increasing and decreasing rather than continuously increasing as the rotational speed increased to twice the first critical speed, which can be explained well by the nonlinear model. The radial growth rate of the whirl motion greatly affects the whirl frequency of the journal and is responsible for the frequency lock in the water-film whip. Further analysis shows that increasing the lubricating water flow rate changes the water-film whirl/whip characteristics, reduces the first critical speed, advances the time when significant water-film whirling motion occurs, and also increases the vibration amplitude at the bearing center which may lead to the rotor-stator rub-impact. The study gives the insight into the water-film whirl and whip in the water lubricated sliding bearing.

数据仓库技术和OLAP的研究

文章介绍了数据仓库和联机分析处理技术的基本概念,分析了数据仓库的WHIPS体系结构和现行的几种联机分析处理模型,在此基础上提出了一种新型联机分析处理模型———对象-关系型联机分析处理模型。

基于更新补偿的实化视图增量过滤研究

针对WHIPS实化视图维护模型不能检测无效增量问题,提出了增量过滤机制。该机制利用视图定义中的约束条件,并通过更新补偿机制,对基表增量进行有效性检测和过滤,减少了网络通信并避免了数据仓库端的无效的视图增量计算。文章最后通过实验对比,证明了这种机制的有效性。

AutoCAD图形与Word相互调用方法的探讨

近年来,由Microsoft公司开发的Word文字处理软件和由AutoDesk公司开发的AutoCAD计算机辅助设计软件包在机械设计、建筑、轻工等领域得到了极为广泛的应用,但他们之间在功能上均存在一定的缺陷。为此,讨论了AutoCAD图形和Word文档相互调用的若干方法,从而提高了它们在工程设计中的使用效率。

Cryptic diversity within three South American whip spider species(Arachnida, Amblypygi)

DEAR EDITOR,Cryptic diversity(CD),the presence of highly divergent phylogenetic lineages within closed morphological species,has been documented for many taxa.Great arachnid orders such as Araneae or Scorpiones are well studied and many cases of CD have been described therein;to date,however,related research on smaller arachnid orders,such as whip spiders(Amblypygi),remains lacking.

Vibration and Control of Pipes Conveying Fluid

The vibration and control of pipes conveying fluid is studied. The solid-liquid coupling vibration equations of the pipe conveying fluid are deduced by Hamilton principle.The direct velocity feedback is used to control the pipe vibration. The whip response and control are discussed.

召回

2011年4月6日．美国消费品安全委员会、加拿大卫生部与williams—Sonoma Inc联合宣布对中国产Whirly Whip热巧克力壶实施自愿性召回。