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Gas adsorption studies of CO2 and N2 in spatially aligned double-walled carbon nanotube arrays
(2013)
Gas adsorption studies (CO2 and N2) over a wide pressure range on vertically, highly aligned dense double-walled carbon nanotube arrays of high purity and high specific surface area are reported. At high pressures, the adsorption capacity of these materials was found to be comparable to those of metal organic frameworks and mesoporous molecular sieves. These highly aligned CNT arrays were chemically modified by treating with oxygen plasma and structurally modified by decreasing the diameter of individual carbon nanotubes. Oxygen plasma treatment led to grafting of a large number of C–O functional groups onto the CNT surface, which further increased the gas adsorption capacity. It was found that gas adsorption is dependent on tube diameter and increases with decrease of the individual CNT diameter in the CNT bundles. As results of our studies we have found that at lower pressure regimes, plasma functionalized carbon nanotubes exhibit better adsorption characteristics whereas at higher pressures, lower diameter carbon nanotube structures exhibited better gas adsorption characteristics.
Background: Increasing awareness of the importance of evidence-based medicine is demonstrated not only by an increasing number of articles addressing it but also by a specialty-wide evidence-based medicine initiative. The authors critically analyzed the quality of reporting of randomized controlled trials published in this Journal over a 21-year period (1990 to 2010).
Methods: A hand search was conducted, including all issues of Plastic and Reconstructive Surgery from January of 1990 to December of 2010. All randomized controlled trials published during this time period were identified with the Cochrane decision tree for identification of randomized controlled trials. To assess the quality of reporting, a modification of the checklist of the Consolidated Standard of Reporting Trials Statement was used.
Results: Of 7121 original articles published from 1990 to 2010 in the Journal, 159 (2.23 percent) met the Cochrane criteria. A significant increase in the absolute number of randomized controlled trials was seen over the study period (p < 0.0001). The median quality of these trials from 1990 to 2010 was "fair," with a trend toward improved quality of reporting over time (p = 0.127).
Conclusions: A favorable trend is seen with respect to an increased number of published randomized controlled trials in Plastic and Reconstructive Surgery. Adherence to standard reporting guidelines is recommended, however, to further improve the quality of reporting. Consideration may be given to providing information regarding the quality of reporting in addition to the "level of evidence pyramid," thus facilitating critical appraisal.
The design of control systems of concentrator photovoltaic power plants will be more challenging in the future. Reasons are cost pressure, the increasing size of power plants, and new applications for operation, monitoring and maintenance required by grid operators, manufacturers and plant operators. Concepts and products for fixed-mounted photovoltaic can only partly be adapted since control systems for concentrator photovoltaic are considerable more complex due to the required high accurate sun-tracking. In order to assure reliable operation during a lifetime of more than 20 years, robustness of the control system is one crucial design criteria. This work considers common engineering technics for robustness, safety and security. Potential failures of the control system are identified and their effects are analyzed. Different attack scenarios are investigated. Outcomes are design criteria that encounter both: failures of system components and malicious attacks on the control system of future concentrator photovoltaic power plants. Such design criteria are a transparent state management through all system layers, self-tests and update capabilities for security concerns. The findings enable future research to develop a more robust and secure control system for concentrator photovoltaics when implementing new functionalities in the next generation.
The communication system of a large-scale concentrator photovoltaic power plant is very challenging. Manufacturers are building power plants having thousands of sun tracking systems equipped with communication and distributed over a wide area. Research is necessary to build a scalable communication system enabling modern control strategies. This poster abstract describes the ongoing work on the development of a simulation model of such power plants in OMNeT++. The model uses the INET Framework to build a communication network based on Ethernet. First results and problems of timing and data transmission experiments are outlined. The model enables research on new communication and control approaches to improve functionality and efficiency of power plants based on concentrator photovoltaic technology.
The design of control systems in large-scale CPV power plants will be more challenging in the future. Reasons are the increasing size of power plants, the requirements of grid operators, new functions, and new technological trends in industrial automation or communication technology. Concepts and products from fixed-mounted PV can only partly be adopted since control systems for sun-tracking installations are considerable more complex due to the higher quantity of controllable entities. The objective of this paper is to deliver design considerations for next generation control systems. Therefore, the work identifies new applications of future control systems categorized into operation, monitoring and maintenance domains. The key-requirements of the technical system and the application layer are identified. In the resulting section, new strategies such as a more decentralized architecture are proposed and design criteria are derived. The contribution of this paper should allow manufacturers and research institutes to consider the design criteria in current development and to place further research on new functions and control strategies precisely.
Member Lens
(2013)
After Image
(2013)
In the brain-cell microenvironment, diffusion plays an important role: apart from delivering glucose and oxygen from the vascular system to brain cells, it also moves informational substances between cells. The brain is an extremely complex structure of interwoven, intercommunicating cells, but recent theoretical and experimental works showed that the classical laws of diffusion, cast in the framework of porous media theory, can deliver an accurate quantitative description of the way molecules are transported through this tissue. The mathematical modeling and the numerical simulations are successfully applied in the investigation of diffusion processes in tissues, replacing the costly laboratory investigations. Nevertheless, modeling must rely on highly accurate information regarding the main parameters (tortuosity, volume fraction) which characterize the tissue, obtained by structural and functional imaging. The usual techniques to measure the diffusion mechanism in brain tissue are the radiotracer method, the real time iontophoretic method and integrative optical imaging using fluorescence microscopy. A promising technique for obtaining the values for characteristic parameters of the transport equation is the direct optical investigation using optical fibers. The analysis of these parameters also reveals how the local geometry of the brain changes with time or under pathological conditions. This paper presents a set of computations concerning the mass transport inside the brain tissue, for different types of cells. By measuring the time evolution of the concentration profile of an injected substance and using suitable fitting procedures, the main parameters characterizing the tissue can be determined. This type of analysis could be an important tool in understanding the functional mechanisms of effective drug delivery in complex structures such as the brain tissue. It also offers possibilities to realize optical imaging methods for in vitro and in vivo measurements using optical fibers. The model also may help in radiotracer biomarker models for the understanding of the mechanism of action of new chemical entities.
This paper describes the magmaOffenburg 3D simulation team trying to qualify for RoboCup 2013. While last year’s TDP focused on different ways how robot behavior can be defined in the magmaOffenburg framework this year we focus on how we statistically evaluate new features on distributed systems. We also show some results gained through such analysis.
Not only is the number of new devices constantly increasing, but so is their application complexity and power. Most of their applications are in optics, photonics, acoustic and mobile devices. Working speed and functionality is achieved in most of media devices by strategic use of digital signal processors and microcontrollers of the new generation. Considering all these premises of media development dynamics, the authors present how to integrate microcontrollers and digital signal processors in the curricula of media technology lectures by using adequate content. This also includes interdisciplinary content that consists of using the acquired knowledge in media software. These entries offer a deeper understanding of photonics, acoustics and media engineering.