Klaschka U.,Hochschule Ulm
Umweltwissenschaften und Schadstoff-Forschung | Year: 2010
Some fragrances used in everyday products are strong contact allergens. Their application in cosmetic products is restricted. However, consumers who want to or need to avoid allergenic fragrances must invest a lot of efforts. Independent support for consumers, e. g. by the German Allergy and Asthma Association (Deutscher Allergie- und Asthmabund e. V., DAAB) or by "Öko-Test", could improve health protection. The analysis of such recommendations, however, reveals that today this support does not guarantee a sufficient consumer protection. Instead other solutions are needed, either easily understandable warning labels on products containing strong allergens, stronger restrictions, or even bans of allergenic fragrances in everyday products. © Springer-Verlag 2010.
Pietzcker T.,Hochschule Ulm |
Von Baum H.,Universitatsklinikum Ulm
Hygiene + Medizin | Year: 2014
Everyday life can no longer be imagined without watching movies. We chose 10 movies thematizing several topics of hospital hygiene and infection control procedures: personal hygiene (hand and skin hygiene), medical devices, food hygiene standards, nosocomial infections and outbreaks.
Chua R.H.,Nanyang Technological University |
Chua R.H.,Robert Bosch GmbH |
Li X.,Nanyang Technological University |
Walter T.,Hochschule Ulm |
And 5 more authors.
Applied Physics Letters | Year: 2016
Zinc oxysulfide buffer layers with [O]:[S] of 1:0, 6:1, 4:1, 2:1, and 1:1 ratios were deposited by atomic layer deposition on Cu(In,Ga)(S,Se)2 absorbers and made into finished solar cells. We demonstrate using Time-Resolved Photoluminescence that the minority carrier lifetime of Zn(O,S) buffered solar cells is dependent on the sulfur content of the buffer layer. τ1 for devices with [O]:[S] of 1:0-4:1 are <10 ns, indicating efficient charge separation in devices with low sulfur content. An additional τ2 is observed for relaxed devices with [O]:[S] of 2:1 and both relaxed and light soaked devices with [O]:[S] of 1:1. Corroborated with one-dimensional electronic band structure simulation results, we attribute this additional decay lifetime to radiative recombination in the absorber due to excessive acceptor-type defects in sulfur-rich Zn(O,S) buffer layer that causes a buildup in interface-barrier for charge transport. A light soaking step shortens the carrier lifetime for the moderately sulfur-rich 2:1 device when excess acceptors are passivated in the buffer, reducing the crossover in the dark and illuminated I-V curves. However, when a high concentration of excess acceptors exist in the buffer and cannot be passivated by light soaking, as with the sulfur-rich 1:1 device, then cell efficiency of the device will remain low. © 2016 AIP Publishing LLC.
Ott T.,Hochschule Ulm |
Walter T.,Hochschule Ulm |
Unold T.,Helmholtz Center Berlin
Thin Solid Films | Year: 2013
Cu(In,Ga)Se2 solar cells exhibit non-idealities with respect to a standard diode especially at low temperatures: a blocking behavior of the dark current in forward direction, a crossover of the dark and illuminated current-voltage-characteristics and a saturation of the open circuit voltage with respect to temperature and illumination intensity. It will be demonstrated that at low temperatures a Cu(In,Ga)Se2 solar cell with a back barrier essentially behaves as a phototransistor with a ZnO-emitter and Schottky collector. Hereby, the base current is provided by photoexcited holes in the field-free region of the absorber. Comparing simulations with measurements it will be illustrated that these non-idealities can be quantitatively explained. It will be shown that depending on the barrier height of the back diode and the doping profile these characteristics even occur at room temperature. This back barrier might be due to a Schottky contact or to a low doping at the back contact and a higher doping level close to the heterointerface. © 2012 Elsevier B.V.
Gutenschwager K.,Hochschule Ulm |
Volker S.,Hochschule Ulm |
Radtke A.,SimPlan Integrations GmbH |
Zeller G.,SimPlan AG
Proceedings - Winter Simulation Conference | Year: 2012
The routing of vehicles or personnel in complex logistics systems is a task that needs to be solved in numerous applications, e.g., detailed models of transport networks or order picking areas. The number of relevant nodes in such networks can easily exceed 10,000 nodes. Often, a basic task is finding the shortest path from one node (start) to another (destination). Within the last years various simulation tools have been extended by respective algorithms. However, the execution time of the simulation model may significantly depend on the number of nodes in the network. We present algorithms from the literature and a comparison of three simulation tools with respect to execution time and model size for different scenarios. We further present an approach to work with so called sub-networks, i.e., the network is separated into areas, where finding the shortest path includes the task of starting at a node in one sub-network with a destination in another one. © 2012 IEEE.