Klein R.,University of Regensburg |
Zech O.,University of Regensburg |
Zech O.,GmbH GmbH |
Maurer E.,University of Regensburg |
And 2 more authors.
Journal of Physical Chemistry B | Year: 2011
Recently, a new family of ionic liquids based on oligoether carboxylates was introduced. 2,5,8,11-Tetraoxatridecan-13-oate (TOTO) was shown to form room-temperature ionic liquids (RTILs) even with small alkali ions such as lithium and sodium. However, the alkali TOTO salts suffer from their extremely high viscosities and relatively low conductivities. Therefore, we replaced the alkali cations by tetraalkylammonium (TAA) ions and studied the TOTO salts of tetraethyl- (TEA), tetrapropyl- (TPA), and tetrabutylammonium (TBA). In addition, the environmentally benign quaternary ammonium ion choline (Ch) was included in the series. All salts were found to be ionic liquids at ambient temperatures with a glass transition typically at around -60 °C. Viscosities, conductivities, solvent polarities, and Kamlet-Taft parameters were determined as a function of temperature. When using quaternary ammonium ions, the viscosities of the resulting TOTO ionic liquids are >600 times lower, whereas conductivities increase by a factor of up to 1000 compared with their alkali counterparts. Solvent polarities further reveal that choline and TAA cations yield TOTO ionic liquids that are more polar than those obtained with the, per se, highly polar sodium ion. Results are discussed in terms of ion-pairing and structure-breaking concepts with regard to a possible complexation ability of the TOTO anion. © 2011 American Chemical Society.
Widemann B.T.,TU Ilmenau |
Lepper M.,GmbH GmbH
Lecture Notes in Informatics (LNI), Proceedings - Series of the Gesellschaft fur Informatik (GI) | Year: 2013
Professional development of software dealing with structured models requires more systematic approach and semantic foundation than standard practice in general-purpose programming languages affords. One remedy is to integrate techniques from other programming paradigms, as seamless as possible and without forcing programmers to leave their comfort zone. Here we present a tool for the implementation of pattern matching as fundamental means of automated data extraction from models of arbitrary shape and complexity in a general-purpose programming language. The interface is simple but, thanks to elaborate and rigorous design, is also light-weight, portable, non-invasive, type-safe, modular and extensible. It is compatible with object-oriented data abstraction and has full support for nondeterminism by backtracking. The tool comes as a library consisting of two levels: elementary pattern algebra (generic, highly reusable) and pattern bindings for particular data models (specific, fairly reusable, user-definable). Applications use the library code in a small number of idiomatic ways, making pattern-matching code declarative in style, easily writable, readable and maintainable. Library and idiom together form a tightly embedded domain-specific language; no extension of the host language is required. The current implementation is in Java, but assumes only standard object-oriented features, and can hence be ported to other mainstream languages. © Gesellschaft für Informatik, Bonn 2013.
Becker R.,City Hospital Brandenburg |
Becker R.,Otto Von Guericke University of Magdeburg |
Mauer C.,City Hospital Brandenburg |
Starke C.,Otto Von Guericke University of Magdeburg |
And 4 more authors.
Knee Surgery, Sports Traumatology, Arthroscopy | Year: 2013
Purpose: Different bearing designs in unicondylar knee arthroplasty (UKA) have been developed in order to influence the rate of polyethylene wear. Increased anteroposterior translation and rotation after UKA has been hypothesized due to changes in joint surface geometry. The mobile bearing design was expected to show increased anteroposterior translation compared to the fixed bearing and biconcave bearing design. Methods: Six human cadaver knees were used for the tests. Anteroposterior and rotational knee stability was analysed in 0°, 30°, 60°, 90° and 120° of knee flexion using a robotic testing system (KR 125, KUKA Robots Augsburg, Germany). Three forces and moments were measured in a Cartesian coordinate system with a resolution of 1.0 N and 0.1 Nm. Results: There was no difference between the native knees and the knees after UKA in AP translation and rotation in all knee flexion angles. The factor knee flexion angle had a significant impact on the anterior translation when the type of bearing was neglected (p ≤ 0.015). Conclusion: This study shows that the natural knee stability in AP translation and rotation can be preserved in UKA. The preserved knee stability in different planes after UKA underlines the advantage of UKA when surgery is required in osteoarthritic changes of the medial compartment. © 2012 Springer-Verlag.
Siweka R.,GmbH GmbH |
Chemical Engineering Transactions | Year: 2012
In 2006 the EN 14491 was published (EN 14491, 2006). This European Standard specifies the basic requirements of design for the selection of a dust explosion venting protective system. Thepresent paper will explain the significant changes between the new revised European Standard and the previous one (EN 14491,2006) which are as follows:(1) Additional Information and requirements for pneumatic conveying of the product with axial or tangential release into vessels and silos.(2) Additional Information and requirements on free fall filling of product from e.g., rotary air locks or screw feeder into vessels and silos.(3) Additional Information and requirement on the effect of vent ducts upon the reduced explosion overpressure.(4)-Additional information of flame and pressure effects outside enclosures.(5)-Information on the influence of the filter elements on the explosion venting has been added.(6)-Information on the design of explosion venting of cyclones has been added. The changes in this standard refers to changes regarding the previous standard, which add new or modify existing technical requirements, in a way that new options are given, but without increasing requirements for equipment that was fully compliant with the previous standard. Therefore these changes will not have to be considered for products in conformity with the preceding edition. Copyright © 2012, AIDIC Servizi S.r.l.
Ranze C.,GmbH GmbH
CEUR Workshop Proceedings | Year: 2015
The mega trend individualization drives product manufacturers towards offering more and more variants of their products. As seen in mass customization scenarios, product configuration based on a modular strategy is an enabler for this trend. The key idea of variant management is to optimize the number of product variants that can be offered to a specific market segment, i.e. outer variety, while reducing the complexity of product development and manufacturing. Production costs are typically kept low by producing a small amount of modules that are generic and common for multiple products within the modular strategy, i.e. inner variety. Classic variant management is driven by the idea of reducing costs between the fields of product design / engineering and manufacturing / logistics. Hence, we see this as efficiency. We apply the same method of optimizing the interplay between outer variety and inner variety to the sales-level; i.e. between the fields of logistics processing and sales / marketing. The product variants that are offered to a specific market segment should be aligned with the market needs. Hence, we see this as effectiveness. We show how the two views on variant management complement one another and how they relate to business economics, namely the economies of scale and the economies of scope. We suggest using a combination of both efficiency and effectiveness to assess the capability of change of product manufacturers that are based on modular systems. Market-oriented variant management involves a number of business processes. A management-ready presentation of the potential that changing these processes has, can significantly influence a company's willingness to invest in such a change.
Siwek R.,GmbH GmbH
Chemical Engineering Transactions | Year: 2012
In December 2008 the VDI-Guideline Part 8: 2008 was published. In this guideline the basic information regarding fire and explosion risks, fire and explosion protection measures are given and aims both the manufacturer's and the user's tasks. In March 2011 the new the VDI-Guideline Part 8.1: 2011 was published. The main information contains examples of preventive fire and explosion protection and constructional measures for fire and explosion protection in elevators. Thanks to the results of extensive explosion trials on a bucket elevator conduced in the last years, important gaps in our knowledge have been filled and new findings regarding explosion venting and explosion suppression gained. These findings are also incorporated in this new guideline Part 8.1. Equations involving numerical values have been developed which represent an optimized mathematical matching of the innumerable experimental investigations, and which, as experience has shown, embrace the conditions of operational practice even for the most unfavourable cases. Both guidelines are the basic for a European standard in form of a Technical Report on explosion protection on elevators. Copyright © 2012, AIDIC Servizi S.r.l.
Paschotta R.,GmbH GmbH
Photonics Spectra | Year: 2014
Researchers share their views on how optical fibers work in different applications with supporting numerical simulations to conduct related investigations. One of the most basic elements in the analysis of optical fibers is the critical angle for reflection at the core/cladding interface. Total internal reflection can occur only if light incident on the fiber end propagates with angles against the fiber axis that are below the critical angle. The overall coupling loss of that fiber joint depends on the distribution of powers over the modes of the input fiber. There are also various surprising features for coupling between single-mode fibers. The coupling loss for any direction of propagation is determined simply by an overlap integral of the two mode functions.
Starck H.,GmbH GmbH
Metal Powder Report | Year: 2010
A study carried out by German hardmetals specialists H C Starck has shown that one of the necessary conditions for improvement is proper choice of the binder alloy composition. Hardmetals were prepared from a WC 0.6 μm by wet milling in ethanol, followed by vacuum drying. In order to compensate for the lower density of the Fe containing alloys compared to Co, the hard metal formulations were changed by weight proportions in order to keep the volume fraction of the binder alloy comparable to WCC08. In addition, K40 hardmetals were prepared from a WC 0.8 μm with 12% Co and 10.4% of a Co-free FeNi binder alloy FeNi 82/18. The hardmetal powders were pressed and sintered in vacuum or in a sinter HIP, if residual porosity was above A02 after vacuum sintering. Unmounted pieces were prepared for hot hardness measurement. The FeNi 82/18 dissolves only carbon, and shows a clear dependence of hot hardness from carbon content at all temperatures until 800°C, but shows a lower hot hardness at 600°C.
Wenzel H.,GmbH GmbH
Proceedings of the Institution of Civil Engineers: Forensic Engineering | Year: 2016
The ancient Greek saying ‘Scio nescio’, ‘I know I don’t know’ (by Socrates, commonly used in its Roman version), applies in structural engineering despite the impression that civil engineers perfectly understand the behaviour of their structures. Failures often hit them by surprise and very often they face more questions than answers. In this environment, forensic engineering helps them understand the performance of structures by using new technologies and materials. They also find that the current standards and practices do not cover all the complexity, record dimensions and non-linear behaviour of the built environment. It is most appropriate to learn from failures, disseminate this information widely and educate the engineering community. With changes in engineering education and often applied standard solutions, the risk of misconception increases. This paper provides an opinion on current practice and informs about the development approaches taken in various regions of the world. © 2016, Thomas Telford Services Ltd. All Rights Reserved.
Sollinger H.-P.,GmbH GmbH
Professional Papermaking | Year: 2014
Since 1980 the paper industry has had to deal with a variety of challenges. Decades of growth culminated in a phase of change and repositioning. Nevertheless, the paper industry is a stable industry with a positive future. Using a 3-phase model, the Chairman of the Management Board of Voith Paper GmbH, Heidenheim/Germany, until July 2014, Dr. Hans-Peter Sollinger, illustrates the changes in the industry since 1980 using the example of Voith Paper as a supplier.