Konzeption und Entwicklung eines Condition Monitoring Systems mit Low Cost Sensoren zur Überwachung von Roboterschwingungen

Im Rahmen dieser Veröffentlichung wird ein Konzept zur Erfassung des Schwingungsverhaltens von Industrierobotern mit Hilfe von Low Cost Sensoren vorgestellt. Durch dieses sollen die dynamischen Eigenschaften des Industrieroboters im gesamten Arbeitsraum untersucht werden. Die Roboterstruktur wird dazu durch eine speziell konstruierte Unwuchtscheibe angeregt. Das Messsystem besteht aus einem Beschleunigungssensor, einem Arduino-Mikrocontroller und einem eigens entwickelten Mess- und Auswerteprogramm in der Softwareumgebung MATLAB®. Die Validierung des Konzeptes erfolgt jeweils mit Messreihen an einem Kragbalken sowie an einem Industrieroboter durch den Vergleich mit einem Referenzmesssystem der Firma Brüel & Kjaer. Durch das entwickelte Low Cost Condition Monitoring System lassen sich die Anregungsfrequenzen und –amplituden mit hinreichender Genauigkeit erfassen und Rückschlüsse auf das Schwingungsverhalten des Industrieroboters ziehen

Excitation mapping of whispering gallery modes in silica microcavities

We report the direct observation of the electromagnetic-field distribution of whispering?gallery modes in silica microcavities (spheres and toroids). It is revealed by their excitation efficiency with a tapered fiber coupler swept along the meridian. The originality of this method lies in the use of the coupler itself for the near field mapping, eliminating the need of additional tools used in previous work. This method is successfully applied to microspheres and microtoroid

FloatingCanvas: quantification of 3D retinal structures from spectral-domain optical coherence tomography

Spectral-domain optical coherence tomography (SD-OCT) provides volumetric images of retinal structures with unprecedented detail. Accurate segmentation algorithms and feature quantification in these images, however, are needed to realize the full potential of SD-OCT. The fully automated segmentation algorithm, FloatingCanvas, serves this purpose and performs a volumetric segmentation of retinal tissue layers in three-dimensional image volume acquired around the optic nerve head without requiring any pre-processing. The reconstructed layers are analysed to extract features such as blood vessels and retinal nerve fibre layer thickness. Findings from images obtained with the RTVue-100 SD-OCT (Optovue, Fremont, CA, USA) indicate that FloatingCanvas is computationally efficient and is robust to the noise and low contrast in the images. The FloatingCanvas segmentation demonstrated good agreement with the human manual grading. The retinal nerve fibre layer thickness maps obtained with this method are clinically realistic and highly reproducible compared with time-domain StratusOCT™

Polarization-sensitive optical frequency domain imaging based on unpolarized light

Polarization-sensitive optical coherence tomography (PS-OCT) is an augmented form of OCT, providing 3D images of both tissue structure and polarization properties. We developed a new method of polarization-sensitive optical frequency domain imaging (PS-OFDI), which is based on a wavelength-swept source. In this method the sample was illuminated with unpolarized light, which was composed of two orthogonal polarization states (i.e., separated by 180° in the Poincaré sphere) that are uncorrelated to each other. Reflection of these polarization states from within the sample was detected simultaneously and independently using a frequency multiplexing scheme. This simultaneous sample probing with two polarization states enabled determination of the depth-resolved Jones matrices of the sample. Polarization properties of the sample were obtained by analyzing the sample Jones matrices through eigenvector decomposition. The new PS-OFDI system ran at 31K wavelength-scans/s with 3072 pixels per wavelength-scan, and was tested by imaging a polarizer and several birefringent tissues such as chicken muscle and human skin. Lastly the new PS-OFDI was applied to imaging two cancer animal models: a mouse model by injecting cancer cells and a hamster cheek pouch model. These animal model studies demonstrated the significant differences in tissue polarization properties between cancer and normal tissues in vivo. © 2011 Optical Society of America

Konzeption und Entwicklung eines Condition Monitoring Systems mit Low Cost Sensoren zur Überwachung von Roboterschwingungen

Im Rahmen dieser Veröffentlichung wird ein Konzept zur Erfassung des Schwingungsverhaltens von Industrierobotern mit Hilfe von Low Cost Sensoren vorgestellt. Durch dieses sollen die dynamischen Eigenschaften des Industrieroboters im gesamten Arbeitsraum untersucht werden. Die Roboterstruktur wird dazu durch eine speziell konstruierte Unwuchtscheibe angeregt. Das Messsystem besteht aus einem Beschleunigungssensor, einem Arduino-Mikrocontroller und einem eigens entwickelten Mess- und Auswerteprogramm in der Softwareumgebung MATLAB®. Die Validierung des Konzeptes erfolgt jeweils mit Messreihen an einem Kragbalken sowie an einem Industrieroboter durch den Vergleich mit einem Referenzmesssystem der Firma Brüel & Kjaer. Durch das entwickelte Low Cost Condition Monitoring System lassen sich die Anregungsfrequenzen und –amplituden mit hinreichender Genauigkeit erfassen und Rückschlüsse auf das Schwingungsverhalten des Industrieroboters ziehen

anterior resection

Purpose: A complication after restorative rectal surgery with a straight anastomosis is low-anterior resection syndrome with a postoperatively deteriorated anorectal function. The colonic J-reservoir is sometimes used with the purpose of reducing these symptoms. An alternative method is to use a simple side-to-end anastomosis or a coloplasty. Material and Methods: Three-hundred fiftyseven patients with rectal cancer undergoing total mesorectal excision (TME). Three-hundred (84.0%) received a low anterior resection with primary anastomosis and colo-rectal n=194 (64.6%) or colo-anal anastomosis n=106 (35.3%). A colonic pouch using the descending colon was created in 24 patients and in 75 patients respectively. Surgical results and complications were recorded. Patients were followed with a functional evaluation at 6 and 12 months postoperatively. Results: Patient characteristics in both groups were very similar regarding gender, age, tumor level, and Dukes ’ stages. A large proportion of the patients received short-term preoperative radiotherapy (72%). There was no significant difference in surgical outcome between the 2 techniques with respect to anastomotic height, perioperative blood loss, , postoperative complications, reoperations, hospital stay or pelvic sepsis rates except the anastomotic stricture rate in the colonic J-Pouch group after coloanal anastomosis (p<0.02). Conclusions: These data show that either a colonic J-pouch or a straight anastomosis performed on the descending colon in low-anterior resection with TME are methods that can be used with similar expected surgical and functional results. Key words: rectal cancer, anterior resection, colo-anal anastomosis, colonic pouch rezim

Coherent nonlinear optics of quantum emitters in nanophotonic waveguides

Coherent quantum optics, where the phase of a photon is not scrambled as it interacts with an emitter, lies at the heart of many quantum optical effects and emerging technologies. Solid-state emitters coupled to nanophotonic waveguides are a promising platform for quantum devices, as this element can be integrated into complex photonic chips. Yet, preserving the full coherence properties of the coupled emitter-waveguide system is challenging because of the complex and dynamic electromagnetic landscape found in the solid state. Here, we review progress toward coherent light-matter interactions with solid-state quantum emitters coupled to nanophotonic waveguides. We first lay down the theoretical foundation for coherent and nonlinear light-matter interactions of a two-level system in a quasi-one-dimensional system, and then benchmark experimental realizations. We discuss higher order nonlinearities that arise as a result of the addition of photons of different frequencies, more complex energy level schemes of the emitters, and the coupling of multiple emitters via a shared photonic mode. Throughout, we highlight protocols for applications and novel effects that are based on these coherent interactions, the steps taken toward their realization, and the challenges that remain to be overcome