Vorrichtung zum beruehrungslosen Erfassen von Abstaenden zu Gegenstaenden

EP 1544572 A UPAB: 20050823 NOVELTY - Contactless measurement device for determining the distance between a railway vehicle and various elements of the permanent way has a reference measurement unit (20) with which one or more distance measurement units (14-17) can be checked by measurement of a distance to a characteristic point on a rail. A correction module is then used to correct other measurements based on the measurement of the distance to the reference point. USE - Contactless measurement device for determining the distance between a railway vehicle and various elements of the permanent way. ADVANTAGE - Distance measurement accuracy is improved

A mechanistic study of Ni-catalyzed carbon dioxide coupling with ethylene towards the manufacture of acrylic acid

The reaction mechanism of CO2 coupling with C2H4 by homogeneous Ni-complexes bearing bidentate phosphorous ligands was studied by means of density functional theory calculations. The reaction is initiated by sequential coordination of C2H4 and CO2 to the Ni center, followed by a facile coupling step, which results in a stable nickelalactone intermediate. Subsequent decomposition of this intermediate through ß-H transfer is the rate-determining step. Together with the following reductive elimination step to form acrylic acid they represent a strongly kinetically-hampered process. Destabilization of the nickelalactone intermediate in the presence of large bite angle bidentate ligands has only a minor effect on the overall reaction energetics. Modifying the electronic properties of ligands is also not effective to drive the reaction in a catalytic manner. These studies indicate that the coupling reaction has to be enforced through an alternative route. It is predicted here that a base-assisted decomposition of the nickelalactone intermediate represents a favorable reaction channel. The factors affecting the reactivity of this route are investigated. The best reactivity corresponds to the CH3OH-solvated CH3ONa that allows the ß-H transfer step to proceed with a barrier of only 49 kJ¿mol-1. Keywords: ab initio calculations; carbon dioxide; homogeneous catalysis; nickel; reaction mechanism

Einfluss der Rauheit auf das Verschleißverhalten von DLC-Schichten

Der niedrige Reibwert und geringe Verschleiß von amorphen Kohlenwasserstoffschichten wird üblicherweise mit einem Transferfilm auf dem Gegenkörper und einer Phasenumwandlung in Verbindung gebracht. In Überrollversuchen wurde der Einfluss der anfänglichen Rauheit auf das Verschleißverhalten untersucht. Der Verschleiß verläuft linear mit der Zeit und hängt dabei vor allem von der Anfangsrauheit ab, er erinnert sich trotz Einglättung der Oberfläche an seine Anfangsrauheit, obwohl sich unabhängig von der Anfangsrauheit eine feste Betriebsrauheit eingestellt hat. Dabei wird ein Aufbau eines Transferfilms sowie eine Absenkung des sp3- Anteils auf dem Transferfilm beobachtet. Die Dicke des Transferfilms hängt dabei ebenfalls von der Anfangsrauheit ab, hat aber scheinbar keinen direkten Einfluss auf die Verschleißtiefe

Protodesylilation of 2,6-disubstituted silylphosphinines. Experimental and theoretical study.

NoteInternational audienc

2.5 - Controlling Laser Material Processing with Real-Time Algorithms on Cellular Neural Networks

Today image processing using a coaxial camera setup is used to monitor the quality of laser material processes such as laser welding, cutting, ablation or scribing. For real-time control of highly dynamic laser processes these systems are far to slow. This article proposes a sensing system for the next step: Using image based quality features in a real-time algorithm to form an instant feedback signal with up to 15 kHz in order to maintain the process in the desired state. The key component of the control system is a camera based on Cellular Neural Networks (CNN). This Single Instruction Multiple Data technology enables real time image processing by integrating processing units in every camera pixel. Moreover each of the pixel units is interconnected with its respective neighbour units which is optimal for most image processing algorithms. An integrated FPGA provides external devices with control feedback signals. In a laser ablation application, which was developed with our partners at Fraunhofer IWS in Dresden, the CNN system is used to provide the trigger signal for a pulse laser by checking optical quality features of a workpiece. The laser pulses should ablate only the top carbonite layer. Defining the reference input variable as the percentage of ablation of the workpiece, the camera system triggers the pulse laser as long as the ablation process needs to remove the upper layer - but no longer. This is done by checking reflection and shape of the ablated underlying gold layer in real time. The image processing algorithm provides a quality rating of the current state of the workpiece and stops the laser ablation process when best quality is achieved. As a result the control algorithm decreases the pulse numbers, saves time and energy and increases the quality of the underlying layer with evaluation and control rates up to 10kHz. In another application, which we have developed with our partners at IFSW Stuttgart and TU Dresden, the real-time algorithm on the CNN system is used to control the power of a laser welding system. By detecting the contour of the full penetration hole and using a special control algorithm the laser power is kept in the optimal range for high quality welding. Compared to conventional systems the frame rate for acquisition, evaluation and controlling rises from about 1 kHz to 14 kHz

The Effect of a Fourth Binding Site on the Stabilization of Cationic SPS Pincer Palladium Complexes : Experimental, DFT, and Mass Spectrometric Studies

International audienc

A mechanistic study of Ni-catalyzed carbon dioxide coupling with ethylene towards the manufacture of acrylic acid

The reaction mechanism of CO2 coupling with C2H4 by homogeneous Ni-complexes bearing bidentate phosphorous ligands was studied by means of density functional theory calculations. The reaction is initiated by sequential coordination of C2H4 and CO2 to the Ni center, followed by a facile coupling step, which results in a stable nickelalactone intermediate. Subsequent decomposition of this intermediate through ß-H transfer is the rate-determining step. Together with the following reductive elimination step to form acrylic acid they represent a strongly kinetically-hampered process. Destabilization of the nickelalactone intermediate in the presence of large bite angle bidentate ligands has only a minor effect on the overall reaction energetics. Modifying the electronic properties of ligands is also not effective to drive the reaction in a catalytic manner. These studies indicate that the coupling reaction has to be enforced through an alternative route. It is predicted here that a base-assisted decomposition of the nickelalactone intermediate represents a favorable reaction channel. The factors affecting the reactivity of this route are investigated. The best reactivity corresponds to the CH3OH-solvated CH3ONa that allows the ß-H transfer step to proceed with a barrier of only 49 kJ¿mol-1. Keywords: ab initio calculations; carbon dioxide; homogeneous catalysis; nickel; reaction mechanism

Preparation and characterization of GaP semiconductor electrodes for photoelectrochemical water splitting

Abstractp-type GaP was systematically examined for photoelectrochemical water splitting. The influence of wet chemical etching and the difference of electrochemical deposition and physical vapor deposition of platinum were investigated. Therefore, each preparation step of GaP was studied by photoelectron emission spectroscopy, atomic force microscopy and photoelectrochemical methods