Combustor Materials Research Studies for High Speed Aircraft in the European Program ATLLAS2

Author(s):  
Marc Bouchez ◽  
Meriam Axtmann ◽  
Cecile Davoine ◽  
Markus Kuhn ◽  
Christian Wilhemi ◽  
...  
Author(s):  
Thomas Quercetti ◽  
Andre Musolff ◽  
Karsten Mu¨ller

In context with disposal container safety assessment of containers for radioactive waste the German Federal Institute for Materials Research and Testing (BAM) performed numerous drop tests in the last years. The tests were accompanied by extensive and various measurement techniques especially by instrumented measurements with strain gages and accelerometers. The instrumentation of a specimen is an important tool to evaluate its mechanical behavior during impact. Test results as deceleration-time and strain-time functions constitute a main basis for the validation of assumptions in the safety analysis and for the evaluation of calculations based on finite-element methods. Strain gauges are useful to determine the time dependent magnitude of any deformation and the associated stresses. Accelerometers are widely used for the measuring of motion i.e. speed or the displacement of the rigid cask body, vibration and shock events. In addition high-speed video technique can be used to visualize and analyze the kinematical impact scenario by motion analysis. The paper describes some selected aspects on instrumented measurements and motion analysis in context with low level radioactive waste (LLW) container drop testing.


2020 ◽  
Vol 9 (5) ◽  
pp. 1854-1860
Author(s):  
Fazilah Hassan ◽  
Argyrios Zolotas ◽  
Shaharil Mohd Shah

The industrial norm of tilting high speed trains, nowadays, is that of Precedence tilt (also known as Preview tilt). Precedence tilt, although succesfull as a concept, tends to be complex (mainly due to the signal interconnections between vehicles and the advanced signal processing required for monitoring). Research studies of early prior to that of precedence tilt schemes, i.e. the so-called Nulling-type schemes, utilized local-per-vehicle signals to provide tilt action (this was essentially a typical disturbance rejection-scheme) but suffered from inherent delays in the control). Nulling tilt may still be seen as an important research aim due to the simple nature and most importantly due to the more straightforward fault detection compared to precedence schemes. The work in this paper presents a substantial extension conventional to robust H∞ mixed sensitivity nulling tilt control in literature. A particular aspect is the use of optimization is used in the design of the robust controller accompanied by rigorous investigation of the conflicting deterministic/stochastic local tilt trade-off 


2021 ◽  
Vol 33 (48) ◽  
pp. 483002
Author(s):  
Nicholas J Terrill ◽  
Andrew J Dent ◽  
Barry Dobson ◽  
Andrew M Beale ◽  
Lisa Allen ◽  
...  

Author(s):  
Allan M. Zarembski

The issue of broken rail risk has been of major concern to railways worldwide, to include passenger and freight railways. Broken rail derailments on high speed passenger operations are of particular concern, as depicted by the consequences of the 2000 Hatfield derailment in the UK. Research studies have shown that the risk of broken rail derailments is directly related to the rate of rail defect development and the associated relationship between service defects and detected defects. This paper examines the relationship between rail defects and broken rail derailments together with techniques used to reduce the risk of these broken rail derailments. Specifically, the paper focuses on the relationship between all defects, service defects and derailments and examines the effect on improved inspection, either through improved inspection technology or improved inspection scheduling, on reducing rail service defects and associated derailments. The paper also examines the levels of broken rail risk that have been found on freight and passenger systems in North America and Europe and provides guidelines for the range of broken rail risk that has been found effective.


MRS Bulletin ◽  
1991 ◽  
Vol 16 (1) ◽  
pp. 17-19
Author(s):  
P.E. Cladis

The goal of this issue of the MRS BULLETIN, with its focus on the physics of complex materials, is to point out some of the fascinating features, both fundamental and applied, of complex materials: liquid crystals and polymers. Over the past 20 years, we have witnessed impressive advances in the understanding of liquid crystals and polymers on all fronts—physics, chemistry, materials research, and applications.Physicists are interested in the fundamentals of a phenomenon. Our assumption is that once we understand how the pieces of a System work, the understanding of how the whole System works immediately follows. However, those of us who have been involved in materials physics research quickly learn that complexity generates rules of its own on scales much larger than the microscopic scale of the molecules involved. Some-times these rules are beautifully simple and elegantly described, but most often they are not. The following articles high-light some important current research in the domain of complex materials, particularly for liquid crystals and polymers.Contributing to this special issue are: Pierre-Gilles de Gennes; J. William Doane; Wolfgang Meier and Heino Finkelmann; Paul Keyes; Patrick Oswald, John Bechhoefer and Francisco Melo; and Walter Zimmerman. They give us their current thinking on polymers in shear, novel electro-mechanical effects observed in polymeric liquid crystals, and how liquid crystals in a solid polymer matrix make useful high-speed color displays.


Author(s):  
Mark Wendel ◽  
David Felde ◽  
Ashraf Abdou ◽  
Bernard Reimer

The Spallation Neutron Source (SNS) facility in Oak Ridge, Tennessee uses a liquid mercury target that is bombarded with protons to produce a pulsed neutron beam for materials research and development. In order to mitigate expected cavitation damage erosion (CDE) of the containment vessel, a two-phase flow arrangement of the target has been proposed and was earlier proven to be effective in significantly reducing CDE in non-prototypical target bodies. This arrangement involves covering vulnerable surfaces with a protective layer of gas. The difficulty lies in establishing a persistent gas layer that is oriented vertically and holds up to the strong buoyancy force and the turbulent mercury flow. Several new multiphase experiments have been completed at the Oak Ridge National Laboratory toward developing such layers. The gas hold-up is accomplished by machining regular features (grooves or pits) into the wall with dimensions on the order of 1 mm. The thickness of the gas layer varies, and it is currently unknown how thick a layer must be in order to successfully mitigate the damage, although this aspect is also under investigation. The paper includes a description of the various tests, a presentation of high-speed video images of the gas/mercury interaction viewed through a transparent window, and a discussion of how the results can be used to design a new SNS target that might be resistant to cavitation damage erosion.


Author(s):  
E.D. Wolf

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.


Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.


Author(s):  
William Krakow

In the past few years on-line digital television frame store devices coupled to computers have been employed to attempt to measure the microscope parameters of defocus and astigmatism. The ultimate goal of such tasks is to fully adjust the operating parameters of the microscope and obtain an optimum image for viewing in terms of its information content. The initial approach to this problem, for high resolution TEM imaging, was to obtain the power spectrum from the Fourier transform of an image, find the contrast transfer function oscillation maxima, and subsequently correct the image. This technique requires a fast computer, a direct memory access device and even an array processor to accomplish these tasks on limited size arrays in a few seconds per image. It is not clear that the power spectrum could be used for more than defocus correction since the correction of astigmatism is a formidable problem of pattern recognition.


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