Fonds Werner Renfer (1898-1936)

Le fonds est constitué de manuscrits, oeuvres publiées, documents biographiques, articles de presse, correspondances, photos et documents divers

Roboter programmieren leicht gemacht

Das BFH-Spin-off Auto-Mate Robotics entwickelt ein System, mit dem sich Roboter schnell und ohne viel Fachwissen programmieren lassen. Es erleichtert die Einführung der Automatisierung in kleinen und mittleren Unternehmen

Experimental investigation into vortex structure and pressure drop across microcavities in 3D integrated electronics

Hydrodynamics in microcavities with cylindrical micropin fin arrays simulating a single layer of a water-cooled electronic chip stack is investigated experimentally. Both inline and staggered pin arrangements are investigated using pressure drop and microparticle image velocimetry (μPIV) measurements. The pressure drop across the cavity shows a flow transition at pin diameter-based Reynolds numbers (Re d) ~200. Instantaneous μPIV, performed using a pH-controlled high seeding density of tracer microspheres, helps visualize vortex structure unreported till date in microscale geometries. The post-transition flow field shows vortex shedding and flow impingement onto the pins explaining the pressure drop increase. The flow fluctuations start at the chip outlet and shift upstream with increasing Re d. No fluctuations are observed for a cavity with pin height-to-diameter ratio h/d=1 up to Re d ~330; however, its pressure drop was higher than for a cavity with h/d=2 due to pronounced influence of cavity wall

Comparative Analysis of Intensive Filial Therapy with Intensive Individual Play Therapy and Intensive Sibling Group Play Therapy with Child Witnesses of Domestic Violence

The purpose of this study was to determine the effectiveness of Intensive Filial Therapy in: (a) improving the self-concept of child witnesses of domestic violence; (b) reducing internalizing behavior problems, such as withdrawal, somatic complaints, anxiety and depression, of child witnesses of domestic violence; (c) reducing externalizing behavior problems, such as aggression and delinquency, of child witnesses of domestic violence; (d) reducing overall behavior problems of child witnesses of domestic violence; and (e) increasing communication of empathy between mothers and child witnesses of domestic violence. A second objective of this study was to compare the effectiveness of Intensive Filial Therapy with Intensive Individual Play Therapy and Intensive Sibling Group Play Therapy with child witnesses of domestic violence. The experimental group consisted of 11 child witnesses of domestic violence whose mothers received 12 Intensive Filial Therapy training sessions within a three week period and had 12 mother-child play sessions. The Intensive Individual Play Therapy comparison group, consisting of 11 child witnesses, and the non-treatment control group, consisting of 11 child witnesses, were utilized from the Kot (1995) study. The Intensive Sibling Group Play Therapy comparison group was utilized from the Tyndall-Lind (1999) study. Children in all studies completed the Joseph Preschool and Primary Self-concept Screening Test and the Child Behavior Checklist. Mothers who received Intensive Filial Therapy training conducted pretest and posttest play sessions for the Measurement of Empathy in Adult-Child Interaction. Analyses of Covariance revealed the children in the experimental group significantly increased in self-concept, and significantly reduced overall behavior problems. A comparison of t-test scores of the pretests and posttests revealed mothers in the experimental group significantly increased communication of empathy to their children

Umsetzung der Brandschutzvorschriften in der Instandhaltung von Blockbauten

Die schweizerischen VKF-Brandschutzvorschriften 2015 definieren die Anforderungen an Bauten und Anlagen. Diese hängen im Wesentlichen von der Gebäudenutzung und den Gebäudeabmessungen ab und richten sich gemäss Art. 2 der VKF-Brandschutznorm an neu zu erstellenden Bauten und Anlagen. Bestehende Bauten sind verhältnismässig an die Brandschutzvorschriften anzupassen, wenn

Analysis of conjugated heat transfer in micro-heat exchangers via integral transforms and non-intrusive optical techniques

The purpose of this paper is to employ the Generalized Integral Transform Technique in the analysis of conjugated heat transfer in micro-heat exchangers, by combining this hybrid numerical-analytical approach with a reformulation strategy into a single domain that envelopes all of the physical and geometric sub-regions in the original problem. The solution methodology advanced is carefully validated against experimental results from non-intrusive techniques, namely, infrared thermography measurements of the substrate external surface temperatures, and fluid temperature measurements obtained through micro Laser Induced Fluorescence. The methodology is applied in the hybrid numerical-analytical treatment of a multi-stream micro-heat exchanger application, involving a three-dimensional configuration with triangular cross-section micro-channels. Space variable coefficients and source terms with abrupt transitions among the various sub-regions interfaces are then defined and incorporated into this single domain representation for the governing convection-diffusion equations. The application here considered for analysis is a multi-stream micro-heat exchanger designed for waste heat recovery and built on a PMMA substrate to allow for flow visualization. The methodology here advanced is carefully validated against experimental results from non-intrusive techniques, namely, infrared thermography measurements of the substrate external surface temperatures and fluid temperature measurements obtained through Laser Induced Fluorescence. A very good agreement among the proposed hybrid methodology predictions, a finite elements solution from the COMSOL code, and the experimental findings has been achieved. The proposed methodology has been demonstrated to be quite flexible, robust, and accurate. The hybrid nature of the approach, providing analytical expressions in all but one independent variable, and requiring numerical treatment at most in one single independent variable, makes it particularly well suited for computationally intensive tasks such as in optimization, inverse problem analysis, and simulation under uncertainty.Indisponível

Vortex shedding from confined micropin arrays

The hydrodynamics in microcavities populated with cylindrical micropins was investigated using dynamic pressure measurements and fluid pathline visualization. Pressure signals were Fourier-analyzed to extract the flow fluctuation frequencies, which were in the kHz range for the tested flow Reynolds numbers (Re) of up to 435. Three different sets of flow dependent characteristic frequencies were identified, the first due to vortex shedding, the second due to lateral flow oscillation and the third due to a transition between these two flow regimes. These frequencies were measured at different locations along the chip (e.g. inlet, middle and outlet). It is established that vortex shedding initiates at the outlet and then travels upstream with increase in Re. The pathline visualization technique provided direct optical access to the flow field without any intermediate post-processing step and could be used to interpret the frequencies determined through pressure measurements. Microcavities with different micropin height-to-diameter aspect ratios and pitch-to-diameter ratios were tested. The tests confirmed an increase in the Strouhal number (associated with the vortex shedding) with increased confinement (decrease in the aspect ratio or the pitch), in agreement with macroscale measurements. The compact nature of the microscale geometry tested, and the measurement technique demonstrated, readily enabled us to investigate the flow past 4,420 pins with various degrees of confinements; this makes the measurements performed and the techniques developed here an important tool for investigating large arrays of similar objects in a flow fiel