Die zweite Phase der Feldbusentwicklung

The past decade may be regarded as the phase of the fundamental developments in fieldbus systems that were based on the OSI model. Today we are entering a second stage. It is the objective of this issue to present the current state and where the further developments will lead to. This introductory article is intended to give an overview on the subject.     

A feasible noise estimation algorithm for resource-limited sensor systems

Fault tolerance and self-checking capabilities are key features of modern smart sensors, which often require the integration of additional signal processing facilities. In high-volume production areas such as automotive applications, however, optimized controllers are employed that typically have only limited computing resources. This paper examines several algorithms to assess the noise in a quasi-closed loop measurement channel under the assumption that the stimulus can be held constant during noise measurement. Starting from the definition of standard deviation, we propose several modifications and obtain an easy-to-implement algorithm relying entirely on addition and shift operations. Numerical experiments based on simulated and measured noise verify the practicability of the approach. The proposed algorithm has already been successfully implemented in a capacitive angular speed sensor system for automotive applications.     

Exogenous Integrin αIIbβ3 Inhibitors Revisited: Past,Present and Future Applications

The integrin αIIbβ3 is the most abundant integrin on platelets. Upon platelet activation, the integrin changes its conformation (inside-out signalling) and outside-in signalling takes place leading to platelet spreading, platelet aggregation and thrombus formation. Bloodsucking parasites such as mosquitoes, leeches and ticks express anticoagulant and antiplatelet proteins, which represent major sources of lead compounds for the development of useful therapeutic agents for the treatment of haemostatic disorders or cardiovascular diseases. In addition to hematophagous parasites, snakes also possess anticoagulant and antiplatelet proteins in their salivary glands. Two snake venom proteins have been developed into two antiplatelet drugs that are currently used in the clinic. The group of proteins discussed in this review are disintegrins, low molecular weight integrin-binding cysteine-rich proteins, found in snakes, ticks, leeches, worms and horseflies. Finally, we highlight various oral antagonists, which have been tested in clinical trials but were discontinued due to an increase in mortality. No new αIIbβ3 inhibitors are developed since the approval of current platelet antagonists, and structure-function analysis of exogenous disintegrins could help find platelet antagonists with fewer adverse side effects.     

Uric Acid: The Sperm-Release Pheromone of the Marine Polychaete Platynereis dumerilii

In the marine polychaete, Platynereis dumerilii, reproductive behavior in the two sexes is synchronized by the consecutive discharge of male and female sex-specific pheromones. After the female releases the eggs into the free water column, immediate fertilization is achieved by several males circling around the eggs emitting sperm clouds. We report the isolation and identification of the sperm-release pheromone present in the coelomic fluid of sexually mature females. Each step in isolation was guided by bioassay. Isolation methods included extraction and solvent partitioning and separation methods included ultrafiltration and high-performance liquid chromatography. Uric acid was identified as the sperm-release pheromone that is discharged by the female with release of the eggs. The threshold concentration for sperm release by males was determined as 0.6 M.     

Ultraviolet photodetectors and readout based on a-IGZO semiconductor technology

In this work, real-time ultraviolet photodetectors are realized through metal–semiconductor–metal (MSM) structures. Amorphous indium gallium zinc oxide (a-IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an all-enhancement a-IGZO thin-film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R , a low response time t _{R E S} , and a good noise equivalent power value NEP .     

Model‐based reconstruction for T1 mapping using single‐shot inversion‐recovery radial FLASH

Quantitative parameter mapping in MRI is typically performed as a two‐step procedure where serial imaging is followed by pixelwise model fitting. In contrast, model‐based reconstructions directly reconstruct parameter maps from raw data without explicit image reconstruction. Here, we propose a method that determines T1 maps directly from multi‐channel raw data as obtained by a single‐shot inversion‐recovery radial FLASH acquisition with a Golden Angle view order. Joint reconstruction of a T1, spin‐density and flip‐angle map is formulated as a nonlinear inverse problem and solved by the iteratively regularized Gauss‐Newton method. Coil sensitivity profiles are determined from the same data in a preparatory step of the reconstruction. Validations included numerical simulations, in vitro MRI studies of an experimental T1 phantom, and in vivo studies of brain and abdomen of healthy subjects at a field strength of 3 T. The results obtained for a numerical and experimental phantom demonstrated excellent accuracy and precision of model‐based T1 mapping. In vivo studies allowed for high‐resolution T1 mapping of human brain (0.5–0.75 mm in‐plane, 4 mm section thickness) and liver (1.0 mm, 5 mm section) within 3.6–5 s. In conclusion, the proposed method for model‐based T1 mapping may become an alternative to two‐step techniques, which rely on model fitting after serial image reconstruction. More extensive clinical trials now require accelerated computation and online implementation of the algorithm. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 254–263, 2016     

Low retaining force optical viewport seal

We report on the experimental realization of an ultrahigh vacuum (UHV) indium sealing between a conflat knife edge and an optical window. The sealing requires a very low clamping force and thus allows for the use of very thin and fragile windows.     

Semi‐Solid Processing of Metal Alloys

Semi‐solid metal casting is an innovative technology for the production of near‐net‐shape parts with demanding mechanical properties. The paper describes different processing routes and materials for semi‐solid‐metal casting (SSM), which have been investigated and also partially developed at the Foundry‐Institute of Aachen University. The standard thixocasting process for aluminium, highly reactive magnesium alloys and steel alloys with high melting points was investigated under variation of a wide range of process parameters. Specially adapted pre‐material production and reheating methods were developed for different materials and their application and future potential is pointed out. The thixocasting experiments were executed on a modified high pressure die‐casting machine with a specially designed “step‐die” providing wall thicknesses from 0.5 to 25 mm. The mechanical properties were tested in dependence of the wall thickness and the metal velocity. The results of these examination show high tensile strength values in combination with very good elongations. The rheocasting process is a new SSM‐forming method with liquid melt as feed‐stock and a high recycling potential. The research results of RCP‐technology (Rheo‐Container‐Process) invented at the Foundry‐Institute and of the Cooling‐Channel‐Process for aluminium and magnesium alloys are promising and are presented in this paper. Studies on semi‐solid processing of magnesium alloys and mixtures of them were conducted by Thixomolding^TM. To establish the most adequate process parameters, the temperature and the mixture relations were varied. Using a mould for tensile test specimens, the mechanical properties and the microstructure evolution could be evaluated. The chemical composition of the different phases was determined using SEM and EDX technologies. Evaluations of the flowing properties were conducted using a spiral mould with a total length of 2m and a cross section of 20mm x 1.5mm.