Operational behavior and application regime assessment of the magnetic acceleration plasma facility IMAX

Design, operation and application of pulsed magnetoplasmadynamic self-field accelerators are described and the facility IMAX (Institut für Raumfahrtsysteme der Universität Stuttgart (IRS), Magnetoplasmadynamic Accelerator-Experiment), is considered in further detail on the basis of an experimental reference condition at a capacitor bank load voltage of 12 kV and an ambient air pressure of 10⁻³ Pa. This high power coaxial accelerator has been investigated for space propulsion and for terrestrial plasma processes in particular for metal treatment. Lessons learnt from the operation of the facility and its potentially dangerous functional behavior are discussed. Its operational sensitivities are depicted by numerical analysis using an advanced snowplow model. The analysis shows consistency with previously reported experimental results.     

Ionic liquid based absorption chillers for usage of low grade waste heat in industry

The standard working pairs for absorption chillers, ammonia/water and water/lithium bromide show problematic behaviours like crystallisation and corrosiveness. Because of their convenient solving properties and their low vapour pressure, ionic liquids are a new promising class of sorbents for absorption cooling purposes. In this study, the working pairs water/1,3‐dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and water/1‐ethyl‐3‐methylimidazolium dimethylphosphate ([EMIM][DMP]) are implemented in AspenPlus. The performance of a single effect cycle with these pairs is simulated and compared to results of a cycle with water/LiBr. For [EMIM][DMP] a coefficient of performance (COP) comparable to that of LiBr or even higher (up to 0.85) is found. [MMIM][DMP] shows a smaller maximum COP but a largely wider operating temperature range than LiBr. Results are compared with those of other groups, discrepancies discussed and improvements suggested. Copyright © 2013 John Wiley & Sons, Ltd.     

Processing Fiber-Reinforced Polymers: Specific Wear Phenomena Caused by Filler Materials

Fiber-reinforced polymers allow for the implementation of plastic materials in structural components. However, increasing incorporation of fibers up to 50 wt% causes accelerated component wear in injection molding machines. In particular, the barrel and screw in the compression zone suffer from increased wear. The abrasive fibers of the compacted polymer pellets in the solid bed protrude from the surfaces of the resin having an abrasive, brush-like behavior. A modified pin-on-disk testing system with specially designed polymer pins was used to emulate the described tribological system in laboratory scale. Through varying contact pressure, temperature, and surface modifications of the counterparts (blank or coated powder-metallurgical steel), abrasive wear as observed in industrial-sized extruder screws could be successfully simulated on a laboratory-scale testing system. Detailed investigations of the pins and disks highlighted that the glass fibers plow and cut the surface leading to abrasion as observed in the real field application. Temperature has been proven to be the most decisive driving force. Surface modifications such as protective physical vapor-deposited CrN coatings are effective against abrasive wear, clearly outperforming untreated steels. The presented pin-on-disk-test setup will improve screening of materials for extruders, thus enhancing the durability of injection molding machines. POLYM. ENG. SCI., 60:78–85, 2020. © 2019 Society of Plastics Engineers     

Lanthanide and Heavy Metal Free Long White Persistent Luminescence from Ti Doped Li–Hackmanite: A Versatile,Low‐Cost Material

Persistent luminescence (PeL) materials are used in everyday glow‐in‐the‐dark applications and they show high potential for, e.g., medical imaging, night‐vision surveillance, and enhancement of solar cells. However, the best performing materials contain rare earths and/or other heavy metal and expensive elements such as Ga and Ge, increasing the production costs. Here, (Li,Na)₈Al₆Si₆O₂₄(Cl,S)₂:Ti, a heavy‐metal‐ and rare‐earth‐free low‐cost material is presented. It can give white PeL that stays 7 h above the 0.3 mcd m^?2 limit and is observable for more than 100 h with a spectrometer. This is a record‐long duration for white PeL and visible PeL without rare earths. The material has great potential to be applied in white light emitting devices (LEDs) combined with self‐sustained night vision using only a single phosphor. The material also exhibits PeL in aqueous suspensions and is capable of showing easily detectable photoluminescence even in nanomolar concentrations, indicating potential for use as a diagnostic marker. Because it is excitable with sunlight, this material is expected to additionally be well‐suited for outdoor applications.     

How Good Is My Test Data? Introducing Safety Analysis for Computer Vision

Good test data is crucial for driving new developments in computer vision (CV), but two questions remain unanswered: which situations should be covered by the test data, and how much testing is enough to reach a conclusion? In this paper we propose a new answer to these questions using a standard procedure devised by the safety community to validate complex systems: the hazard and operability analysis (HAZOP). It is designed to systematically identify possible causes of system failure or performance loss. We introduce a generic CV model that creates the basis for the hazard analysis and—for the first time—apply an extensive HAZOP to the CV domain. The result is a publicly available checklist with more than 900 identified individual hazards. This checklist can be utilized to evaluate existing test datasets by quantifying the covered hazards. We evaluate our approach by first analyzing and annotating the popular stereo vision test datasets Middlebury and KITTI. Second, we demonstrate a clearly negative influence of the hazards in the checklist on the performance of six popular stereo matching algorithms. The presented approach is a useful tool to evaluate and improve test datasets and creates a common basis for future dataset designs.     

Numerical Characterization of the Bubble Rise Behavior in Viscoelastic Liquids

The bubble rise behavior in viscoelastic media is analyzed numerically with CFD. Three different constitutive models, Giesekus, linear and exponential Phan‐Thien‐Tanner, are used to evaluate three different biopolymer solutions. The terminal rise velocity over a range of bubble sizes is validated against experimental data. The local velocity fields are compared with respect to the shape and onset of the negative wake. Furthermore, the normal and shear components of the stress fields, transformed according to the local flow direction, are given. The simulations are performed with a volume of fluid solver in OpenFOAM.     

Age-related decline in auditory plasticity: Experience dependent changes in gap detection as measured by prepulse inhibition in young and aged rats.

Young adult and aged F344 rats were compared on a silent gap variant of the prepulse inhibition paradigm. Animals were tested using a 50-ms single tone cue, followed by 8 days of silent gap testing. The first 3 days of gap testing were long gaps (range 2 to 100 ms) followed by 5 days of short gaps (range 2 to 10 ms). The effects of gap length, prior experience, and age, on the magnitude and direction (facilitation vs. attenuation) of the acoustic startle response, were examined. The young rats showed stronger and more reliable acoustic startle responses (uncued trials) during all acoustic startle tasks as compared to the old. The younger animals also exhibited a more consistent attenuated response across cues and days. Depending on silent gap length, both reduction (inhibition) and enhancement (facilitation) of startle were observed. Finally, only the young adult animals showed an experience-related shift from facilitation to attenuation in response to very short silent gap cues, and this initial early facilitation predicted later attenuation following additional experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)