Filtern
Erscheinungsjahr
Dokumenttyp
- Wissenschaftlicher Artikel (1082)
- Konferenzveröffentlichung (344)
- Teil eines Buches (Kapitel) (321)
- Beitrag zu einer (nichtwissenschaftlichen) Zeitung oder Zeitschrift (237)
- Buch (Monographie) (219)
- Bericht (74)
- Video (60)
- Vorlesung (46)
- Sonstiges (45)
- Rezension (27)
Sprache
- Deutsch (1980)
- Englisch (532)
- Französisch (4)
- Mehrsprachig (2)
- Spanisch (2)
- Rumänisch (1)
Schlagworte
- Robotik (30)
- Flugkörper (21)
- UAV (21)
- Journalismus (15)
- Bionik (11)
- Rettungsrobotik (8)
- 3D Modell (7)
- Akkreditierung (7)
- E-Learning (7)
- Juristenausbildung (7)
Institut
- Wirtschaftsrecht (834)
- Institut für Internetsicherheit (262)
- Wirtschaft und Informationstechnik Bocholt (254)
- Informatik und Kommunikation (220)
- Institut für Innovationsforschung und -management (194)
- Westfälisches Institut für Gesundheit (141)
- Westfälisches Energieinstitut (83)
- Wirtschaft Gelsenkirchen (65)
- Maschinenbau Bocholt (60)
- Elektrotechnik und angewandte Naturwissenschaften (59)
This paper aims to compare cobalt-based (type Stellite 6) and nickel-based self-fluxing alloys (type NiCrBSiMo) regarding both their cavitation erosion resistance and corrosion resistance. The two types of protective layers were thermally sprayed onto a substrate of martensitic stainless steel. In order to improve the layers' characteristics and their metallurgical bonding to the substrate, the Stellite 6 coating was laser remelted, while the NiCrBSiMo coating was treated by flame fusion. The cavitation erosion resistance of the two materials was evaluated by measurements of the mean depth of erosion developed during a testing period of 165 minutes, using a 20 kHz ultrasonic vibrator at a peak-to-peak amplitude of 50 μm. In addition, the corrosion resistance of the layers was assessed by potentiodynamic corrosion tests carried out in H2SO4 + NaCl solution at room temperature, using calomel as reference electrode. In order to highlight the differences regarding the behaviour of the two protective materials, the authors also carried out microstructural investigations of the layers before and after exposure to cavitation and corrosion. The investigations showed that both types of layers can provide improved protection of the martensitic stainless steel substrate against cavitation, whilst the NiCrBSiMo coating additionally confers significantly increased resistance to corrosion.
Optimization of the laser remelting process for HVOF-sprayed Stellite 6 wear resistant coatings
(2016)
Cobalt base alloys are used in all industrial areas due to their excellent wear resistance. Several studies have shown that Stellite 6 coatings are suitable not only for protection against sliding wear, but also in case of exposure to impact loading. In this respect, a possible application is the protection of hydropower plant components affected by cavitation. The main problem in connection with Stellite 6 is the deposition procedure of the protective layers, both welding and thermal spraying techniques requesting special measures in order to prevent the brittleness of the coating. In this study, Stellite 6 layers were HVOF thermally sprayed on a martensitic 13-4 stainless steel substrate, as usually used for hydraulic machinery components. In order to improve the microstructure of the HVOF-sprayed coatings and their adhesion to the substrate, laser remelting was applied, using a TRUMPF Laser type HL 124P LCU and different working parameters. The microstructure of the coatings, obtained for various remelting conditions, was evaluated by light microscopy, showing the optimal value of the pulse power, which provided a homogenous Stellite 6 layer with good adhesion to the substrate.
Based on the fact that titanium and titanium alloys have poor fretting fatigue resistance and poor tribological properties, it is necessary to apply some surface engineering methods in order to increase the exploitation characteristics of these materials. One may either implement some surface treatment technologies or even deposit overlay coatings by thermal spraying.
The present study is focused on the achieved properties of the ceramic coatings (Al2O3 + 13 wt.% TiO2) deposited onto a titanium substrate using high velocity oxygen fuel (HVOF) and plasma spraying (APS) respectively.
The effect of the deposition method on the microstructure, phase constituents, and mechanical properties of the ceramic coatings was investigated by means of scanning electron microscopy (SEM), X-ray diffraction technique (XRD) and nanoindentation tests. The sliding wear performances of the Al2O3–TiO2 coatings were tested using a pin on disk wear tester.
Interessengerechte Lösung gesucht! Der BGH zu Verlegerbeteiligungen an Ausschüttungen der VG Wort
(2016)
EuGH verteilt Ohrfeigen
(2015)
Das Kreuz mit dem Kopftuch
(2015)
Der diskreditierte Staat
(2015)
Ausverkauf der Demokratie
(2015)
Die ewigen Sklaven
(2015)
Eigentum verpflichtet
(2016)
Um die Wasserstofftechnik in Zukunft wirtschaftlich und damit kommerziell am Markt verfügbar werden zu lassen, sind heute noch immer große Forschungs- und Entwicklungsanstrengungen notwendig. Dabei erfordert die Entwicklung von optimierten Komponenten wie beispielsweise der Membran-Elektroden-Einheit (MEA – engl. Membrane Electrode Assembly) für Brennstoffzellen sowie Elektrolyseure reproduzierbare und homogene Prüfbedingungen. Für diesen Zweck ist ein Prüfsystem auf Basis eines von der Westfälischen Hochschule (WHS) patentierten modularen Stackkonzepts mit hydraulischer Verpressung entworfen und realisiert worden. Mit dem hier vorgestellten System ist es möglich, auf Einzelzellenbasis mehrere Proben zum gleichen Zeitpunkt unter identischen Umgebungsbedingungen auf ihre Charakteristik hin zu untersuchen.
Since the 1980’s, against the backdrop of global warming and the decline of conventional energy resources, low emission and renewable energy systems have gotten into the focus of politics as well as research and development. In order to decrease the emission of greenhouse gases Germany intents to generate 80% of its electrical energy from renewable and low emission sources by 2050. For low emission electricity generation hydrogen operated fuel cells are a potential solution. However, although fuel cell technology has been well known since the 19th century cost effective materials are needed to achieve a breakthrough in the market.
Proton Exchange Membrane Fuel Cells with Carbon Nanotubes as Electrode Material
At the Westphalian Energy Institute of the Wesphalian University of Applied Sciences one main focus is on the research of proton exchange membrane fuel cells (PEMFC). PEMFC membrane electrode assemblies (MEA) consist of a polymer membrane with electrolytic properties covered on both sides by a catalyst layer (CL) as well as a porous and electrical conductive gas diffusion layer (GDL).
For PEMFC carbon nanotubes (CNT) have ideal properties as electrode material concerning electrical conductivity, oxidation resistance and media transport. CNTs are suitable for the use as catalyst support material within the CL due to their large surface in comparison to conventional carbon supports. Furthermore, oxygen plasma treated CNTs show electrochemical activity referred to hydrogen adsorption and desorption, which has been shown by cyclic voltammetry in 0.5 M sulfuric acid solution. According to the PEMFCs anode a GDL coated with oxygen plasma activated CNTs has promising properties to significantly reduce catalyst content (e.g. platinum) of the anodic CL.
Frauenspezifische Gründungsförderung: politically correct, aber betriebswirtschaftlich sinnvoll?
(2003)
"Alas, poor Yorick". Dienstleistungsproduktion im Bildungsbereich und die Mitwirkung der Studenten
(2005)
Die Zukunft des Coaching
(2015)
This report gives a brief overview to the state of the art of PEM fuel cell technology and a description of a newly developed fuel cell stack concept. One main research activity at the Westphalian Energy Institute of the Westphalian University of Applied Sciences is the development of PEM fuel cells, for which a range of different materials have been investigated for fuel cell pole plate construction. Whereas graphite is a material which has suitable properties concerning conductivity as well as manufacturing e.g. for milling, stainless steel foils are suitable for economical hydroforming processes. However, with steel coating is necessary to increase corrosion resistance as well as electrical conductivity. A new fuel cell stack design is currently under development using separated single fuel cells with hydraulic cell compression. The advantages of this stack concept are modularity, effective heat exchanging and constant, uniform cell compression which are further described in this work.
The membrane electrode assemblies (MEA) for polymer electrolyte membrane fuel cells (PEMFC) developed at the Westphalian Energy Institute are based on oxygen plasma activated carbon nanotubes (CNT) doped with platinum particles. For electrode preparation an ink is used containing the activated CNTs as well as hydrophobic and hydrophilic material in solved form. After this ink is sprayed onto a graphitic substrate platinum particles are deposited by pulse plating method, where the plasma activation enhances CNT dispersibility as well as platinum deposition. This materials mixture is structured in nanoscale with the aim to increase the catalyst particles’ specific surface. For low reactance at operation, homogeneous compression of the MEA’s layers is necessary within a PEMFC. A novel stack architecture for electrochemical cells, especially PEMFC as well as PEM electrolysers, has been developed in order to achieve ideal cell operation conditions. Single cells of such a stack are inserted into flexible slots that are surrounded by a hydraulic medium which is pressurised during operation in order to achieve an even compression and cooling of the stack’s cells. With this stack design it has been possible to construct a test facility for simultaneous characterisation of several MEA samples. As compression and temperature conditions of every single sample are the same, the effects of e.g. different electrode configurations can be investigated with the novel test system.
Social innovations «meet social needs», are «good for society» and «enhance society’s capacity to act». But what does their rising importance tell us about the current state of public policy in Europe and its effectiveness in achieving social and economic goals? Some might see social innovation as a critique of public intervention, filling the gaps left by years of policy failure. Others emphasise the innovative potential of cross-boundary collaboration between the public sector, the private sector, the third sector and the household.
This paper explores the conditions under which the state either enables or constrains effective social innovation by transcending the boundaries between different actors. We argue that social innovation is closely linked to public sector innovation, particularly in relation to new modes of policy production and implementation, and to new forms of organisation within the state that challenge functional demarcations and role definitions.
Solutions to empower and (re-)engage vulnerable and marginalised populations to unfold their hidden potential allowing them to fully participate the social, economic, cultural and political life, necessarily involve institutional change. This in turn necessitates understanding the processes and mechanisms by which social innovations lead to in-stitutional change. Considering the specific nature of social innova-tions as interactive, generative and contextualised phenomena while maintaining that many practices at the micro-level can add up to patterns and regularities at the macro-level, middle-range theorising (MRT) is proposed as an appropriate method to theoreti-cally underpin and substantiate theoretical advancements towards a multidisciplinary perspective on the economic dimensions of social innovation, identifying the direction of future empirical inquiries.
In an effort to better understand the various forms of social innovation, mapping has become a common and widely applied method for gaining insights into social innovation practices. The transdisciplinary nature of social innovation research has led to a plurality of distinct approaches and methods. Given the increasing interest in social innovation, and the apparent endeavour among policymakers to utilise social innovation to address current societal challenges, it is argued that mapping efforts need to be streamlined in order to make better use of their results. The article describes 17 ongoing or recently finalised research projects on social innovation and their methodological approaches on “mapping” social innovations. It provides a systematic overview on project objectives, SI definitions and mapping approaches for each of the scrutinised projects and ends with a synoptical analysis on methods, objectives and missing research.
Fußball und Ökonomie
(2006)
Die Arbeit unternimmt einen Versuch, die Gründe für die besondere Korruptionsanfälligkeit bestimmter Länder auszumachen und Lösungsansätze zu liefern. Sie fokussiert sich dabei auf die Aspekte, die die Unterschiede zwischen einzelnen Ländern erklären. Dabei werden neben rein rechtlichen und ökonomischen Überlegungen insbesondere rechts- und wirtschaftssoziologische Erklärungsansätze untersucht.
Bereits im April 2012 wurde im HZwei Magazin ein Stackkonzept für PEM-Brennstoffzellen vorgestellt, bei dem im Gegensatz zu der heute üblichen bipolaren Zellenanordnung mit mechanischer Verpressung Einzelzellen über ein Hydraulikmedium verpresst werden. Die Vorteile der homogenen Verpressung und Temperierung der Zellen wurden hierbei herausgestellt. Zwischenzeitlich ist basierend auf diesem Ansatz das Labormuster eines PEM-Elektrolyseurs entwickelt worden, bei dem der produzierte Wasserstoff oder auch der Sauerstoff mit hohen Ausgangsdrücken, z.B. auf einem für Power-2-Gas-Anlagen günstigem Druckniveau, direkt bereitgestellt werden kann.