Resource efficiency and environmental impact of fiber reinforced plastic processing technologies

The process energy demand and the environmental indicators of two carbon fiber reinforced plastic process chains have been investigated. More precisely, the impact of different production set-ups for a standard textile preforming process using bindered non-crimp fabric (NCF) and a material efficient 2D dry-fiber-placement (DFP) process are analyzed. Both 2D preforms are activated by an infrared heating system and formed in a press. The resin-transfer-molding (RTM) technology is selected for subsequent processing. Within a defined process window, the main parameters influencing the process energy demand are identified. Varying all parameters, a reduction of 77% or an increase of 700% of the electric energy consumption compared to a reference production set-up is possible, mainly depending on part size, thickness, and curing time. For a reference production set-up, carbon fiber production dominates the environmental indicators in the product manufacturing phase with a share of around 72–80% of the total global warming potential (GWP). Thus, the reduction of production waste, energy efficient carbon fiber production, and the use of renewable energy resources are the key environmental improvement levers. For the production of small and thin parts in combination with long curing cycles, the influence of the processing technologies is more pronounced. Whereas for a reference production set-up, only 10% (NCF–RTM) and 15% (DFP–RTM) of the total GWP are caused by the processing technologies, a production set-up leading to a high process energy demand results in a share of 40% (NCF–RTM) and 49% (DFP–RTM), respectively.     

High resolution long range ISAR imaging systems

The requirements for high resolution, long range ISAR imaging systems capable of recognising targets have been outlined. Systems meeting these requirements and operating at mm-wavelengths have been proposed. The systems consist of N phased locked transmitters feeding as many antennas in phase. Quasi-optical power addition at the target occurs. In the receive mode all antennas are connected in phase. These systems can at least double the range obtained by utilising a system having one transmitter/antenna combination. Several realisation options have been studied including the annular synthesis antenna systems which offer some advantages over more conventional realisations.     

Identification of quantitative trait loci involved in contextual and auditory-cued fear conditioning in BXD recombinant inbred strains.

Fear conditioning shows associations formed between contextual or auditory stimuli with an unconditioned stimulus. Inbred mouse strains differ in their ability to demonstrate fear conditioning, suggesting at least a partial genetic influence. The present study identified the possible chromosomal loci regulating fear conditioning in BXD recombinant inbred strains using quantitative trait loci (QTL) analysis. Estimates of heritability for all 3 measures of conditioning were about .28. Correlational analyses between genetic markers and strain means identified multiple putative QTLs. The strongest associations were on Chromosomes 1 and 17 for freezing to the context, Chromosome 12 for freezing to an altered context, and Chromosome 1 for freezing to the auditory stimulus. Overlapping QTLs may indicate some common genes that underlie aspects of this learning task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Condition Evolution in Bridge Management Systems and Corrosion-Induced Deterioration

Condition assessment in the Swiss bridge management system (KUBA-MS) is performed on the element level. Five condition states are defined based on visual appearance. In order to forecast the condition states of any given element at any given time a relationship must be established between the element age and its condition state. This relationship, which describes the condition evolution, can be obtained empirically from statistical analysis of pairs of consecutive condition assessments (inspections). Markov chains are used in KUBA-MS to represent condition evolution and the transition probabilities are determined using regression analysis of pairs of inspections. Unfortunately there are almost no inspection data for the worst and second worst condition states. The forecasts made using Markov chains are therefore not always reliable. In this paper an alternative approach is suggested, which takes into consideration the physical phenomena underlying element deterioration. This alternative approach is applied to chloride-induced corrosion of steel reinforcement, by far the most common deterioration mechanism in Switzerland. The chloride-induced corrosion is modeled mathematically and numerical simulations of the condition evolution for different values of model parameters are performed. The simulation results have been mapped to condition states as defined in KUBA-MS and Markov transition matrices have been calibrated to fit simulation results.     

Characterization of the ozone zero phenomenon by infrared spectroscopy

The presence of a small amount of nitrogen in the feed gas is necessary to generate ozone efficiently out of oxygen. Operating an ozone generator with ultra-pure oxygen for extended periods results in highly deteriorated ozone generation efficiency. In extreme cases, when the nitrogen levels in the feed gas are in the lower ppm range, the efficiency of the ozone generation process even drops to zero. In this article, we present our results concerning the correlation between the N₂O₅ concentration in the off-gas and the ozone generation efficiency. After the ozone generator is run for a well-defined amount of time with an oxygen–nitrogen mixture, the N₂ supply is shut off, and the behavior of the system is monitored by near-infrared spectroscopy. Different surface materials lead to different temporal behavior of both the nitrogen oxide levels and the ozone concentration after shutting down the nitrogen supply. The measurements show a good correlation between the evolution of ozone generation efficiency and the changes of the N₂O₅ concentration in the off-gas.     

Intelligent framework for radio access network design

Wireless Networks - The evolution of 5G networks over the last few years has introduced a variety of technologies for more efficient radio access networks (RANs), which end up in ultra-dense...     

Flux-based level-set method for two-phase flows on unstructured grids

In this paper we deal with the application of the flux-based level set method to moving interface computations on unstructured grids. The focus lies on the overcoming of the known difficulties of level set methods, e.g. accurate computations of important geometric properties, reliable and precise reinitialization of the level set function and the adaption of standard discretization methods to the moving boundary case. The basic building block of our approach is the high-resolution flux-based level set method for general advection equation (Frolkovi? and Mikula in SIAM J Sci Comput 29(2):579–597, 2007, Frolkovi? and Wehner in Comput Vis Sci 12(6):626–650, 2009). We extend this method for the problem of reinitialization of the level set function on unstructured grids by using quadratic interpolation to compute distances for nodes close to the interface. To realize numerical simulation for some applications with moving boundaries, we adapt the approach of ghost fluid method (Gibou and Fedkiw in J Comput Phys 202:577–601, 2005) for unstructured grids. The idea is to describe the development of the moving boundary with a level set formulation while the computational grid remains fixed and the boundary conditions are enforced using some extrapolation. Our main motivation is the numerical solution of two-phase incompressible flow problems. Additionally to previously mentioned steps, we introduce further numerical schemes in the framework of finite volume discretization for the flow. Possible jumps of the pressure and the directional derivative of velocity at the interface are modeled directly within the method using the approach of extended approximation spaces. Besides that, an algorithm for the computations of curvature is considered that exhibits the second order accuracy for some examples. Numerical experiments are provided for the presented methods.     

Tribological problems in sodium-cooled nuclear power plants

Owing to a possible future shortage of uranium sodium-cooled fast breeder reactors are becoming important. Tribological processes in these facilities, especially in their nuclear components, are of special interest to reactor designers. However, reactor-specific operating conditions do not provide any parameters suitable for establishing reliable working tribosystems between the mating interfaces of contacting components. The friction and wear behaviour of materials has been extensively investigated under special reactor conditions. Work is being carried out on the equipment criteria characteristics of the frictional systems, the surface macroroughness and the chemical reactivity of liquid sodium. The current state of knowledge concerning the selection of materials, the interpretation of test data and engineering design is surveyed.