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排序方式: 共有2092条查询结果,搜索用时 31 毫秒
51.
Itzhak I. Maor Katharina Kruppa Adi Rozencweig Amir Sterzer Frank Steinbach Vadim Beilin Bernd Breidenstein Gennady E. Shter Meirav Mann-Lahav Armin Feldhoff Gideon S. Grader 《Advanced functional materials》2023,33(49):2304464
Calcium cobaltite Ca3Co4−xO9+δ (CCO) is a promising p-type thermoelectric (TE) material for high-temperature applications in air. The grains of the material exhibit strong anisotropic properties, making texturing and nanostructuring mostly favored to improve thermoelectric performance. On the one hand multitude of interfaces are needed within the bulk material to create reflecting surfaces that can lower the thermal conductivity. On the other hand, low residual porosity is needed to improve the contact between grains and raise the electrical conductivity. In this study, CCO fibers with 100% flat cross sections in a stacked, compact form are electrospun. Then the grains within the nanoribbons in the plane of the fibers are grown. Finally, the nanoribbons are electrospun into a textured ceramic that features simultaneously a high electrical conductivity of 177 S cm−1 and an immensely enhanced Seebeck coefficient of 200 µV K−1 at 1073 K are assembled. The power factor of 4.68 µW cm−1 K−2 at 1073 K in air surpasses all previous CCO TE performances of nanofiber ceramics by a factor of two. Given the relatively high power factor combined with low thermal conductivity, a relatively large figure-of-merit of 0.3 at 873 K in the air for the textured nanoribbon ceramic is obtained. 相似文献
52.
Junying Min Patrick Seim Denis Störkle Lars Thyssen Bernd Kuhlenkötter 《International Journal of Material Forming》2017,10(5):729-739
A thermal model was built to account for the effects of geometrical parameters of sheet specimen, process parameters and material parameters on the temperature increase of the sheet specimen in Electricity-Assisted Incremental Sheet Forming (EISF). In the EISF, the local area of sheet specimen contacting with a forming tool is heated by direct current, which flows through the forming tool to the sheet specimen. EISF experiments of two high strength steel sheets were carried out to validate the thermal model. The thermal model can be integrated into the control program of EISF system to achieve more accurate temperature control. 相似文献
53.
Bernd Seifert 《Datenschutz und Datensicherheit - DuD》2011,35(7):446-446
Aus den Datenschutzbeh?rden
überwachung mit Videokameras durch nicht-?ffentliche Stellen 相似文献54.
To realise the potentials of CRM (customer relationship management), relationship-specific processes need to be designed and implemented in companies. This is all the more important and complicated in business networks where two or more actors collaborate to serve the customers. A good collaboration within business networks is the basis for understanding the customer process and identifying customer needs. But, even in these days of customer orientation, transaction orientation is still a matter of strong interest, and the following questions remain to be answered: What is the difference between relationship-oriented processes and transaction-oriented processes, and how can relationship-oriented processes be designed for a business network? The authors give first answers to both questions by using a systematic, goal-oriented specialisation of generic actions. To give an example, one relationship-oriented process will be designed and specified for a certain customer process in the course of this paper. 相似文献
55.
(O)mür (O)cal 《国际自动化与计算杂志》2011,8(2):254-261
The coefficient diagram method (CDM) is one of the most effective control design methods. It creates control systems that
are very stable and robust with responses without the overshoot and small settling time. Furthermore, all control parameters
of the control systems are changed by varying some adjustment parameters in CDM depending on the demands. The model reference
adaptive systems (MRAS) are the systems that follow and change the control parameters according to a given model reference
system. There are several methods to combine the CDM with MRAS. One of these is to use the MRAS parameters as a gain of the
CDM parameters. Another is to directly use the CDM parameters as the MRAS parameters. In the industrial applications, the
system parameters can be changed frequently, but if the controller, by self-tuning, recalculates and develops its own parameters
continuously, the system becomes more robust. Also, if the poles of the controlled systems approach the jw axis, the response of the closed-loop MRAS becomes more and more insufficient. In order to obtain better results, CDM is
combined with a self-tuning model reference adaptive system. Systems controlled by a model reference adaptive controller give
responses with small or without overshoot, have small settling times, and are more robust. Thus, in this paper, a hybrid combination
of MRAS and CDM is developed and two different control structures of the control signal are investigated. The two methods
are compared with MRAS and applied to real-time process control systems. 相似文献
56.
Michael R. Dörfel Bert Jüttler Bernd Simeon 《Computer Methods in Applied Mechanics and Engineering》2010,199(5-8):264-275
Isogeometric analysis based on non-uniform rational B-splines (NURBS) as basis functions preserves the exact geometry but suffers from the drawback of a rectangular grid of control points in the parameter space, which renders a purely local refinement impossible. This paper demonstrates how this difficulty can be overcome by using T-splines instead. T-splines allow the introduction of so-called T-junctions, which are related to hanging nodes in the standard FEM. Obeying a few straightforward rules, rectangular patches in the parameter space of the T-splines can be subdivided and thus a local refinement becomes feasible while still preserving the exact geometry. Furthermore, it is shown how state-of-the-art a posteriori error estimation techniques can be combined with refinement by T-splines. Numerical examples underline the potential of isogeometric analysis with T-splines and give hints for further developments. 相似文献
57.
Hummel M Garth C Hamann B Hagen H Joy KI 《IEEE transactions on visualization and computer graphics》2010,16(6):1319-1328
Integral surfaces are ideal tools to illustrate vector fields and fluid flow structures. However, these surfaces can be visually complex and exhibit difficult geometric properties, owing to strong stretching, shearing and folding of the flow from which they are derived. Many techniques for non-photorealistic rendering have been presented previously. It is, however, unclear how these techniques can be applied to integral surfaces. In this paper, we examine how transparency and texturing techniques can be used with integral surfaces to convey both shape and directional information. We present a rendering pipeline that combines these techniques aimed at faithfully and accurately representing integral surfaces while improving visualization insight. The presented pipeline is implemented directly on the GPU, providing real-time interaction for all rendering modes, and does not require expensive preprocessing of integral surfaces after computation. 相似文献
58.
Henning Gruendl Patrick Riehmann Yves Pausch Bernd Froehlich 《Computer Graphics Forum》2016,35(3):321-330
We present a natural extension of two‐dimensional parallel‐coordinates plots for revealing relationships in time‐dependent multi‐attribute data by building on the idea that time can be considered as the third dimension. A time slice through the visualization represents a certain point in time and can be viewed as a regular parallel‐coordinates display. A vertical slice through one of the axes of the parallel‐coordinates display would show a time‐series plot. For a focus‐and‐context Integration of both views, we embed time‐series plots between two adjacent axes of the parallel‐coordinates plot. Both time‐series plots are drawn using a pseudo three‐dimensional perspective with a single vanishing point. An independent parallel‐coordinates panel that connects the two perspectively displayed time‐series plots can move forward and backward in time to reveal changes in the relationship between the time‐dependent attributes. The visualization of time‐series plots in the context of the parallel‐coordinates plot facilitates the exploration of time‐related aspects of the data without the need to switch to a separate display. We provide a consistent set of tools for selecting and contrasting subsets of the data, which are important for various application domains. 相似文献
59.
60.
Crusta: A new virtual globe for real-time visualization of sub-meter digital topography at planetary scales 总被引:1,自引:0,他引:1
Tony Bernardin Eric CowgillOliver Kreylos Christopher BowlesPeter Gold Bernd HamannLouise Kellogg 《Computers & Geosciences》2011,37(1):75-85
Virtual globes are becoming ubiquitous in the visualization of planetary bodies and Earth specifically. While many of the current virtual globes have proven to be quite useful for remote geologic investigation, they were never designed for the purpose of serving as virtual geologic instruments. Their shortcomings have become more obvious as earth scientists struggle to visualize recently released digital elevation models of very high spatial resolution (0.5-1 m2/sample) and extent (>2000 km2). We developed Crusta as an alternative virtual globe that allows users to easily visualize their custom imagery and more importantly their custom topography. Crusta represents the globe as a 30-sided polyhedron to avoid distortion of the display, in particular the singularities at the poles characteristic of other projections. This polyhedron defines 30 “base patches,” each being a four-sided region that can be subdivided to an arbitrarily fine grid on the surface of the globe to accommodate input data of arbitrary resolution, from global (BlueMarble) to local (tripod LiDAR), all in the same visualization. We designed Crusta to be dynamic with the shading of the terrain surface computed on-the-fly when a user manipulates his point-of-view. In a similarly interactive fashion the globe's surface can be exaggerated vertically. The combination of the two effects greatly improves the perception of shape. A convenient pre-processing tool based on the GDAL library facilitates importing a number of data formats into the Crusta-specific multi-scale hierarchies that enable interactive visualization on a range of platforms from laptops to immersive geowalls and caves. The main scientific user community for Crusta is earth scientists, and their needs have been driving the development. 相似文献