Refine
Year of publication
- 2024 (3)
- 2023 (14)
- 2022 (37)
- 2021 (23)
- 2020 (35)
- 2019 (27)
- 2018 (22)
- 2017 (27)
- 2016 (17)
- 2015 (23)
- 2014 (40)
- 2013 (36)
- 2012 (20)
- 2011 (29)
- 2010 (35)
- 2009 (35)
- 2008 (28)
- 2007 (24)
- 2006 (29)
- 2005 (39)
- 2004 (35)
- 2003 (25)
- 2002 (33)
- 2001 (27)
- 2000 (35)
- 1999 (28)
- 1998 (28)
- 1997 (31)
- 1996 (44)
- 1995 (24)
- 1994 (30)
- 1993 (23)
- 1992 (17)
- 1991 (11)
- 1990 (11)
- 1989 (16)
- 1988 (16)
- 1987 (20)
- 1986 (20)
- 1985 (16)
- 1984 (14)
- 1983 (14)
- 1982 (10)
- 1981 (14)
- 1980 (7)
- 1979 (9)
- 1978 (3)
- 1977 (3)
- 1976 (1)
- 1975 (4)
- 1974 (1)
- 1973 (1)
- 1972 (1)
Institute
- Fachbereich Energietechnik (1115) (remove)
Language
- English (588)
- German (524)
- Multiple languages (1)
- Dutch (1)
- Spanish (1)
Document Type
- Article (609)
- Conference Proceeding (259)
- Book (125)
- Part of a Book (84)
- Doctoral Thesis (10)
- Conference: Meeting Abstract (7)
- Report (7)
- Other (4)
- Talk (3)
- Diploma Thesis (2)
Keywords
- Blitzschutz (18)
- Lightning protection (11)
- Earthquake (5)
- Diversity Management (4)
- Energy storage (4)
- Power plants (4)
- Risikomanagement (4)
- Seismic design (4)
- reinforced concrete (4)
- Associated liquids (3)
A German–Brazilian research project investigates sugarcane as an energy plant in anaerobic digestion for biogas production. The aim of the project is a continuous, efficient, and stable biogas process with sugarcane as the substrate. Tests are carried out in a fermenter with a volume of 10 l.
In order to optimize the space–time load to achieve a stable process, a continuous process in laboratory scale has been devised. The daily feed in quantity and the harvest time of the substrate sugarcane has been varied. Analyses of the digester content were conducted twice per week to monitor the process: The ratio of inorganic carbon content to volatile organic acid content (VFA/TAC), the concentration of short-chain fatty acids, the organic dry matter, the pH value, and the total nitrogen, phosphate, and ammonium concentrations were monitored. In addition, the gas quality (the percentages of CO₂, CH₄, and H₂) and the quantity of the produced gas were analyzed.
The investigations have exhibited feasible and economical production of biogas in a continuous process with energy cane as substrate. With a daily feeding rate of 1.68gᵥₛ/l*d the average specific gas formation rate was 0.5 m3/kgᵥₛ. The long-term study demonstrates a surprisingly fast metabolism of short-chain fatty acids. This indicates a stable and less susceptible process compared to other substrates.
A promising approach to reduce the system costs of molten salt solar receivers is to enable the irradiation of the absorber tubes on both sides. The star design is an innovative receiver design, pursuing this approach. The unconventional design leads to new challenges in controlling the system. This paper presents a control concept for a molten salt receiver system in star design. The control parameters are optimized in a defined test cycle by minimizing a cost function. The control concept is tested in realistic cloud passage scenarios based on real weather data. During these tests, the control system showed no sign of unstable behavior, but to perform sufficiently in every scenario further research and development like integrating Model Predictive Controls (MPCs) need to be done. The presented concept is a starting point to do so.
Control of Aharonov-Bohm oscillations in a AlGaAs/GaAs ring by asymmetric and symmetric gate biasing
(2001)
Reinforced concrete (RC) frames with masonry infills are frequently used in seismic regions all over the world. Generally masonry infills are considered as nonstructural elements and thus are typically neglected in the design process. However, the observations made after strong earthquakes have shown that masonry infills can modify the dynamic behavior of the structure significantly. The consequences were total collapses of buildings and loss of human lives. This paper presents the new system INODIS (Innovative Decoupled Infill System) developed within the European research project INSYSME (Innovative Systems for Earthquake Resistant Masonry Enclosures in RC Buildings). INODIS decouples the frame and the masonry infill by means of special U-shaped rubbers placed in between frame and infill. The effectiveness of the system was investigated by means of full scale tests on RC frames with masonry infills subjected to in-plane and out-of-plane loading. Furthermore small specimen tests were conducted to determine material characteristics of the components and the resistances of the connections. Finally, a micromodel was developed to simulate the in-plane behavior of RC frames infilled with AAC blocks with and without installation of the INODIS system.
Das Transportsystem BANDIT zur Messung von Halbwertszeiten kurzlebiger, neutronenarmer Isotope
(1974)
Laut Zukunftsinstitut (2010) stellt die Individualisierung eine langfristige und nachhaltige Veränderung dar, die die gesamte Gesellschaft (den einzelnen Menschen, Unternehmen, den Staat) betrifft und Auswirkungen auf nahezu alle Lebensbereiche (z. B. Arbeit, Wohnen, Partnerschaft) hat. Die Individualisierung beschreibt dabei die Entwicklung hin zur Fokussierung persönlicher Interessen und Lebensentscheidungen der einzelnen Person (Kunze, Individualisierung, 2011). Der Grund für diese Entwicklung sind laut Kunze (Individualisierung, 2011) Treiber wie steigendes Vermögen, Bildung und Mobilität, was die einzelne Person unabhängiger von größeren Gemeinschaften macht und mehr Freiheit zur Selbstverwirklichung bietet. Als eine Konsequenz daraus werden Wertevorstellungen nicht mehr einfach hingenommen, sondern für die eigene Person überprüft und individualisiert (Kunze, Individualisierung, 2011). So wies Beck bereits 1996 darauf hin, dass Individualisierung meint „erstens die Auflösung und zweitens die Ablösung industriegesellschaftlicher Lebensformen durch andere, in denen die Einzelnen ihre Biographie selbst herstellen, inszenieren, zusammenflickschustern müssen“ (Beck, Die Erfindung des Politischen, 1996, S. 150).
The increasing share of renewable electricity in the grid drives the need for sufficient storage capacity. Especially for seasonal storage, power-to-gas can be a promising approach. Biologically produced methane from hydrogen produced from surplus electricity can be used to substitute natural gas in the existing infrastructure. Current reactor types are not or are poorly optimized for flexible methanation. Therefore, this work proposes a new reactor type with a plug flow reactor (PFR) design. Simulations in COMSOL Multiphysics ® showed promising properties for operation in laminar flow. An experiment was conducted to support the simulation results and to determine the gas fraction of the novel reactor, which was measured to be 29%. Based on these simulations and experimental results, the reactor was constructed as a 14 m long, 50 mm diameter tube with a meandering orientation. Data processing was established, and a step experiment was performed. In addition, a kLa of 1 h−1 was determined. The results revealed that the experimental outcomes of the type of flow and gas fractions are in line with the theoretical simulation. The new design shows promising properties for flexible methanation and will be tested.
Producing fresh water from saline water has become one of the most difficult challenges to overcome especially with the high demand and shortage of fresh water. In this context, as part of a collaboration with Germany, the authors propose a design and implementation of a pilot multi-stage solar desalination system (MSD), remotely controlled, at Douar Al Hamri in the rural town of Boughriba in the province of Berkane, Morocco. More specifically, they present their contribution on the remote control and supervision system, which makes the functioning of the MSD system reliable and guarantees the production of drinking water for the population of Douar. The results obtained show that the electronic cards and computer communication software implemented allow the acquisition of all electrical (currents, voltages, powers, yields), thermal (temperatures of each stage), and meteorological (irradiance and ambient temperature), remote control and maintenance (switching on, off, data transfer). By comparing with the literature carried out in the field of solar energy, the authors conclude that the MSD and electronic desalination systems realized during this work represent a contribution in terms of the reliability and durability of providing drinking water in rural and urban areas.
The Solar-Institut Jülich (SIJ) and the companies Hilger GmbH and Heliokon GmbH from Germany have developed a small-scale cost-effective heliostat, called “micro heliostat”. Micro heliostats can be deployed in small-scale concentrated solar power (CSP) plants to concentrate the sun's radiation for electricity generation, space or domestic water heating or industrial process heat. In contrast to conventional heliostats, the special feature of a micro heliostat is that it consists of dozens of parallel-moving, interconnected, rotatable mirror facets. The mirror facets array is fixed inside a box-shaped module and is protected from weathering and wind forces by a transparent glass cover. The choice of the building materials for the box, tracking mechanism and mirrors is largely dependent on the selected production process and the intended application of the micro heliostat. Special attention was paid to the material of the tracking mechanism as this has a direct influence on the accuracy of the micro heliostat. The choice of materials for the mirror support structure and the tracking mechanism is made in favor of plastic molded parts. A qualification assessment method has been developed by the SIJ in which a 3D laser scanner is used in combination with a coordinate measuring machine (CMM). For the validation of this assessment method, a single mirror facet was scanned and the slope deviation was computed.
IEC Technical Committee 81 is currently creating the new IEC 62305 series of standards on Lightning Protection. Working Group 9 is responsible for Part 2 of this series, which deals with the assessment and management of risk its CDV (Committee Draft for Voting) stage and has been circulated to National Committees for comment. The paper details the development of the Simplified IEC Risk Assessment Calculator software tool as described in Informative Annex J of IEC62305-2 Ed.1/CDV 2. This tool is intended as a simplified implementation of the more rigorous treatment of risk management found in the written document. It is designed to be relatively intuitive for users who wish to obtain an initial assessment of risk sensitivity, but should not be considered a substitute to a full understanding of the methods provided in the standard when dealing with more complicated structures or those where greater risks to personal or system operation are involved.