处理器性能推动车载娱乐系统的发展

以前,汽车还只是一种普通而简单的运输工具.随着电子时代的来临,从防刹车死锁到汽车仪表板,电子和半导体器件在汽车领域的应用变得日益广泛.现在,应用在汽车中的电子娱乐设备将更直接的出现在你面前,比如一个后排座的DVD播放器(其实可以把一个车载收音机也称作娱乐设备,但是它不能像DVD播放器那样令人兴奋).实际上,人们已经有能力在汽车中集成具有无线连接能力的DVD播放器、移动电话、全球定位系统、MP3播放器、卫星电台和因特网浏览器,所有这些都可以通过语音识别和中央控制系统来操控.     

Investitionsbedarf und zukünftige Bedeutung der Versorgungssicherheit in Europa und Österreich

Europe urgently needs an investment boom in the fields of power generation, transmission, and distribution. Until 2030 the current generation portfolio will de facto have to be replaced. Especially in the liberalized market environment, investors rely on a clear and uncompromising regulatory environment, which is still lacking today. The investments required will only happen, if political commitment results in easier and fast-track licensing procedures. Clearly formulated energy targets for Europe and uncompromising free market approaches at EU and national level are the key to guarantee trust in a sufficiently stable regulatory environment. They are also a prerequisite for ensuring that market signals for investments will be acted upon.     

Ultrawideband Radar Measurements of Thickness of Snow Over Sea Ice

An accurate knowledge of snow thickness and its variability over sea ice is crucial in determining the overall polar heat and freshwater budget, which influences the global climate. Recently, algorithms have been developed to extract snow thicknesses from satellite passive microwave data. However, validation of these data over the large footprint of the passive microwave sensor has been a challenge. The only method used thus far has been with meter sticks during ship cruises. To address this problem, we developed an ultrawideband frequency-modulated continuous-wave radar to measure the snow thickness over sea ice. We synthesized a very linear chirp signal by using a phase-locked loop with a digitally generated chirp signal as a reference to obtain a fine-range resolution. The radar operates over the frequency range from 2-8 GHz. We made snow-thickness measurements over the Antarctic sea ice by operating the radar from a sled in September and October 2003. We performed radar measurements over 11 stations with varying snow thicknesses between 4 and 85 cm. We observed an excellent agreement between radar estimates of snow thickness with physical measurements, achieving a correlation coefficient of 0.95 and a vertical resolution of about 3 cm. Comparison of simulated radar waveforms using a simple transmission line model with the measurements confirms our expectations that echoes from snow-covered sea ice are dominated by reflections from air-snow and snow-ice interfaces.     

MIMO systems with full and reduced hardware complexity

MIMO (multiple-input-multiple-output) systems propose enormous gains in the capacity of wireless systems without requiring more spectral resources. This paper first gives an overview of the use of MIMO for diversity and spatial multiplexing, and the use of channel state information in MIMO systems. It then explores the use of antenna selection as a means for the reduction of the hardware complexity. It is shown that the performance in a spatial-multiplexing application is almost as good as that of full-complexity systems as long as the number of RF chains is at least as large as the number of data streams.     

Nichtlineare Trajektorienfolgeregelung für einen Laborhelikopter

This contribution is devoted to the nonlinear tracking control problem of the laboratory experiment helicopter 3DOF distributed by Quanser. The laboratory experiment belongs to the class of mechanical systems with three degrees-of-freedom and two control inputs. It is well known that the systematic design of nonlinear controllers for underactuated mechanical systems is a challenge compared to fully actuated systems. On certain simplifying assumptions, which very well apply to the operating range of practical interest, we can show that the mathematical model is configuration flat. Thereby, a mechanical system is said to be configuration flat if it is differential flat and the flat outputs solely depend on the generalized coordinates of the mechanical system. The controller design is based on a formulation of the mechanical system on a Riemannian manifold where the kinetic energy serves as a natural Riemannian metric. In a first step a nonlinear tracking controller including an integral part in the linear error system is designed by means of a quasi-static state feedback. In a second step the design of the tracking controller is based on the theory of exact linearization utilizing the so-called dynamic extension algorithm. The experimental results of both controllers are compared and discussed in detail. In particular, the quasi-static state feedback controller shows an excellent tracking behavior. The performance as being obtained by the nonlinear controlled cannot be achieved by conventional linear control strategies.     

Ein Beitrag zur nichtlinearen Fahrdynamik-regelung: die differentielle Flachheit des Einspurmodells

This contribution is primarily concerned with the system analysis of the bicycle dynamics, revealing the differential flatness property as a main result. A physically relevant representative for the flat output is introduced, with its components given as the lateral and the longitudinal velocity of a distinguished point located on the longitudinal axis of the vehicle. This flatness property is shown for the front-, rear- and all-wheel driven vehicle, without referring to particular representatives of the functions modelling the lateral tire forces. Following the flatness based control theory, a novel approach to nonlinear vehicle dynamics control is discussed.