Zur Berechnung von Holz‐Beton‐Verbundträgern mit Methoden der mathematischen Optimierung

Holz‐Beton‐Verbundkonstruktionen weisen als hybride Tragwerke gegenüber reinen Holz‐ bzw. Stahlbetonkonstruktionen zahlreiche Vorteile auf. Wesentlich für die Effizienz der Hybridbauweise ist die Ausbildung der Verbundfuge. Der vorliegende Beitrag stellt ein neues Verbundelement für Straßenbrücken in Holz‐Beton‐Verbundbauweise vor, welches im Rahmen eines Forschungsprojekts an der Bauhaus‐Universität Weimar entwickelt wurde. Die rechnerische Analyse der Verbundkonstruktion erfolgt — abweichend von den im Hybridbau bisher üblichen Berechnungsmethoden — unter Anwendung von Energiemethoden und Nutzung von Algorithmen der mathematischen Optimierung. Calculation of timber‐concrete composite structures using mathematical optimization methods. Timber‐concrete composite structures have many advantages over conventional timber and re inforced concrete structures. The efficiency of such hybrid structures significantly depends on the properties of the com posite joint. This article presents a novel structural element for the joint of timber‐concrete composite bridges, which was developed as part of a research project at the Bauhaus‐Universität Weimar. In contrast to standard calculation methods, an energy method and the mathematical optimization is applied for the numerical analysis of the hybrid structure.     

PE100材料在燃气施工中的应用

文章介绍了PE100管材的性能以及PE100和PE80管材性能的比较,并以实例介绍了PE100材料在燃气施工中的应用。     

Identifizierung der Nitratabbauprozesse und Prognose des Nitratabbaupotenzials in den Sedimenten des Hessischen Rieds

Microbial denitrification contributes significantly to the mitigation of nitrate contamination in sedimentary aquifers by reducing nitrate coupled to the consumption of organic carbon (heterotrophic) and iron sulphides like pyrite (autotrophic). However, these phases are often only present in trace amounts and can become depleted, so that denitrification will eventually cease. In order to implement measures within the EC-Water Framework Directive, we investigated the denitrification potential and the denitrification processes in the sediments of the Hessian Ried. The reduction potential was quantified and characterized by solid-phase analyses of drill core samples. Depth-oriented investigations of hydrochemistry (i.e. stable isotopes, N_2Excess) allowed determining nitrate input, reduction progress and average reduction kinetics upstream of selected wells. Despite low sulphide contents (max. 123 mg-S/kg), autotrophic denitrification was typically the dominant process. The results can be used to delineate risk areas, downstream of which denitrification can be expected to cease in the near future.     

A combined ion-sputtering and electron-beam annealing device for the in vacuo postpreparation of scanning probes

We describe the setup, characteristics, and application of an in vacuo ion-sputtering and electron-beam annealing device for the postpreparation of scanning probes (e.g., scanning tunneling microscopy (STM) tips) under ultrahigh vacuum (UHV) conditions. The proposed device facilitates the straightforward implementation of a common two-step cleaning procedure, where the first step consists of ion-sputtering, while the second step heals out sputtering-induced defects by thermal annealing. In contrast to the standard way, no dedicated external ion-sputtering gun is required with the proposed device. The performance of the described device is demonstrated by SEM micrographs and energy dispersive x-ray characterization of electrochemically etched tungsten tips prior and after postprocessing.     

Novel manufacturing process of hollow polymer microspheres

A novel manufacturing process of gas-filled, hollow, poly-butyl-2-cyanoacrylate (PBCA) microspheres in an aqueous phase is the subject of this paper. The two-step process enables the control of the particle-wall size, as well as the particle size. Particles of this type are useful in the medical and pharmaceutical industry for diagnostic purposes in connection with ultrasound and for life or food science applications, such as taste masking, release on demand, etc. Depending upon the process conditions, the particle size ranges from 1 to . The microparticles are formed by using surfactant-stabilized microbubbles, which act as a template. At the interfacial area of these templates, PBCA nanoparticles create deposits that form the particle wall, as the result of a partial filming process. The density of the particles has been calculated as ranging from 100 up to and the volume fraction of the entrapped gas can be 5% or more. The developed process can operate on a scale of several kilograms.     

Understanding simultaneous double-disk grinding: operation principle and material removal kinematics in silicon wafer planarization

Simultaneous double-disk grinding (DDG) is a novel and powerful technology for precision-machining mono-crystalline silicon slices (“wafers”). With DDG the extreme degrees of planarity can be achieved, which the fabrication of micro-electronic devices with minimum lateral feature dimensions of 90 nm and below demands. In DDG, both sides of the wafer are ground simultaneously between two opposite grinding wheels on collinear spindle axes. It is a chuck-less process, in which the workpiece is machined in “free-floating” fashion. Machining kinematics, removal mechanism, and resulting wafer shape differ from those known from (chuck-mounted) single-side grinding or double-sided batch lapping, which are conventionally used in mechanical wafer shaping. This article explains the kinematics of DDG and derives the basic, method-inherent features always observed on DDG-ground wafers from simple kinematic considerations without further model assumptions: global wafer shape, center dip (“navel”), edge thickness roll-off, and symmetries. The expected results are compared with experimental data.     

Common browsing and retrieval of technical and experimental data for steady state experiments

Steady state experiments like Wendelstein 7-X have to deal with large amounts of data of different kind. Discharge lengths may last from less than a second up to 30 min. During this time diagnostics will measure data in different discharge phases with different rates depending on the physical program. Furthermore the technical configuration of all devices must be logged during the discharge as well as between experiment phases. This is necessary to allow supervision of constantly running devices. All measured data must be stored together in a common database to make it easily accessible and reduce the effort to combine data. Because of these requirements a continuous data acquisition system must be provided where data may exist at any time. Intelligent methods for browsing and retrieval of the acquired data from the common database are desired. This includes calendar-based time interval selection, overview plots for intervals that cover several days and online views of the last stored data. The contribution will explain the challenges and the advantages induced by this kind of data access methods. Existing and planned solutions for Wendelstein 7-X will be depicted. Particularly the “Data Browser” – a graphical tool specially designed to fulfil these tasks at W7-X – will be presented.     

Development and validation status of the IFMIF High Flux Test Module

The development of the IFMIF (International Fusion Material Irradiation Facility) High Flux Test Module in the EVEDA (Engineering Validation and Engineering Design Activities) phase up to 2013 includes conceptual design, engineering analyses, as well as design and engineering validation by building of prototypes and their testing. The High Flux Test Module is the device to facilitate the irradiation of SSTT samples of RAFM steels at temperatures 250–550 °C and up to an accumulated irradiation damage of 150 dpa. The requirements, the current design and the performance of the module are discussed, and the development process is outlined.