http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Rain-wind induced vibrations of cables in laminar and turbulent flow
Peil, U.,Dreyer, O. Techno-Press 2007 Wind and Structures, An International Journal (WAS Vol.10 No.1
In the last decades there have been frequent reports of oscillations of slender tension members under simultaneous action of rain and wind - characterized by large amplitudes and low frequencies. The members, e.g. cables of cable-stayed bridges, slightly inclined hangers of arch bridges or cables of guyed-masts, show a circular cross section and low damping. These rain-wind induced vibrations negatively affect the serviceability and the lifespan of the structures. The present article gives a short literature review, describes a mathematical approach for the simulation of rain-wind induced vibrations, sums up some examples to verify the calculated results and discusses measures to suppress the vibrations.
Modeling of rain-wind induced vibrations
Peil, Udo,Nahrath, Niklas Techno-Press 2003 Wind and Structures, An International Journal (WAS Vol.6 No.1
Rain-wind induced vibrations of cables are a challenging problem in the design of cable-stayed bridges. The precise excitation mechanism of the complex interaction between structure, wind and rain is still unknown. A theoretical model that is able to accurately simulate the observed phenomena is not available. This paper presents a mathematical model describing rain-wind induced vibrations as movement-induced vibrations using the quasi-steady strip theory. Both, the vibrations of the cable and the movement of the water rivulet on the cable surface can be described by the model including all geometrical and physical nonlinearities. The analysis using the stability and bifurcation theory shows that the model is capable of simulating the basic phenomena of the vibrations, such as dependence of wind velocity and cable damping. The results agree well with field data and wind tunnel tests. An extensive experimental study is currently performed to calibrate the parameters of the model.
Fatigue of tubular steel lighting columns under wind load
Peil, U.,Behrens, M. Techno-Press 2002 Wind and Structures, An International Journal (WAS Vol.5 No.5
Lighting and traffic signal columns are mainly stressed by excitation due to natural, gusty wind. Such columns typically have a door opening about 60 cm above ground level for the connection of the buried cable with the column's electric system. When the columns around this notch are inadequately designed, vibrations due to gusty winds will produce considerable stress amplitudes in this area, which lead to fatigue cracks. To give a realistic basis for a reliable and economic design of lighting and traffic signal columns, a number of experimental and theoretical investigations have been made. The proposed design concept allows the life of such columns to be assessed with a satisfactory degree of accuracy.
Space vector pulse width amplitude modulation strategy for three-level direct matrix converter
Ye, Peile,Cheng, Qiming The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.7
The total harmonic distortion and switching stress of a three-level direct matrix converter (TLDMC) is greatly reduced in comparison with those of a conventional matrix converter (MC). Meanwhile, the TLDMC leads to major advantages in comparison with existing multi-level AC-DC-AC converter topologies in terms of reduced switch counts and lowered switching power loss. In this paper, a space vector pulse width amplitude modulation (SVPWAM) strategy for the TLDMC is proposed, which can reduce the number of switching actions and improve the voltage utilization by eliminating the zero vector of each sector. An indirect modulation model of a TLDMC is discussed according to the topology of TLDMC in this paper. For the space vector modulation of the TLDMC, the space vector pulse width modulation (SVPWM) with a zero-vector of the fictitious rectifier stage is improved to form the SVPWAM. In addition, the virtual space vector pulse width modulation (VSVPWM) strategy is used for the fictitious inverter stage. Finally, simulation and experimental results verify the correctness of the proposed method.
정패영 ( Cheng Peiling ) 전북대학교 인문학연구소 2017 건지인문학 Vol.0 No.18
Postmodern novelists always have doubt aout the authoritarianism, they devote themselves not only to break the homogeneous hostorical descriptions from official medias, but also to narrate history tales. Postmodern novelists give the readers a multivariate point of view to discover the conflicts and artificiality behind the history. Soong Ching-ling and Soong May-ling were the famous sisters in Chinese history. Official medias praised their marriage and deified their husbands, Sun Yat-sen and Chiang Kai-shek. However the Taiwanese writer, Ping Lu, re-narrated the relationships between the Soong`s sisters and their husands in her works “Love and Revolution(行道天涯)” and “Bailingjian(百齡箋)”. This study discussed and reinterpreted the impressions of the Soong`s sisters in the two works of Ping Lu by a female reader`s point of view.
Fundamental restrictions for the closed-loop control of wind-loaded, slender bridges
Kirch, Arno,Peil, Udo Techno-Press 2009 Wind and Structures, An International Journal (WAS Vol.12 No.5
Techniques for stabilising slender bridges under wind loads are presented in this article. A mathematically consistent description of the acting aerodynamic forces is essential when investigating these ideas. Against this background, motion-induced aerodynamic forces are characterised using a linear time-invariant transfer element in terms of rational functions. With the help of these functions, the aeroelastic system can be described in the form of a linear, time-invariant state-space model. It is shown that the divergence wind speed constitutes an upper bound for the application of the selected mechanical actuators. Even active control with full state feedback cannot overcome this limitation. The results are derived and explained with methods of control theory.
Transfer function approximation of motion-induced aerodynamic forces with rational functions
Kirch, Arno,Peil, Udo Techno-Press 2011 Wind and Structures, An International Journal (WAS Vol.14 No.2
For a detailed investigation of the dynamic behaviour of slender bridges under wind action especially the motion-induced fluid forces should be available not only for harmonic motions but also for more general ones. If linear transfer behaviour is assumed, the force-displacement relation for almost arbitrary motions can be handled in the frequency domain using aerodynamic transfer functions. In aerospace engineering as well as in bridge engineering, these functions are usually approximated by special kinds of complex-valued rational functions which depend on complex frequencies. The quality of this approximation is evaluated for several bridge cross sections in this article. It is shown that rational functions are for some sections scarcely suitable to realistically represent the transfer behaviour of motion-induced aerodynamic forces for arbitrarily complex frequencies.
Limitations for the control of wind-loaded slender bridges with movable flaps
Kirch, Arno,Peil, Udo Techno-Press 2012 Wind and Structures, An International Journal (WAS Vol.15 No.5
This article presents theoretical investigations on techniques for the improvement of the dynamic characteristics of slender bridges under wind action. Aerodynamically effective control shields are applied as controlled actuators. The first part of the article describes the modelling of the uncontrolled aeroelastic system. Acting aerodynamic forces are consistently characterised using linear time-invariant transfer elements in terms of rational functions. On this basis, two configuration levels of the uncontrolled system are represented with linear time-invariant state-space models and investigated. The second part of the article addresses controller design and the behaviour of the controlled aeroelastic system. Both fundamental limits for stabilisation and the efficiency for attenuating the influence of gusts are described for different actuator mechanisms. The results are derived and discussed with methods of control theory.