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The properties of diamond make it an attractive material for MEMS and sensor devices. We present the feasibility to fabricate membranes and cantilevers made of nano-(micro-) crystalline diamond films grown on Si/SiO2 substrates using microwave chemical vapour deposition (MWCVD). The patterning of micromechanical structures was performed by a combined process of femtosecond laser ablation and wet etching. We designed cantilever structures with varying lengths and widths (25, 50, 100, 200 and 300 μm). The cantilevers were made in a symmetric left- and right-hand configuration. An additional laser treatment was used to modify the mechanical properties of the left-hand cantilever. The deflection of the laser-treated, and non-treated sections was measured. The global mechanical system properties were simulated and corresponded with high accuracy to the measured results of deflection.
The properties of SiC and diamond make them attractive materials for MEMS and sensor devices. We innovated specific laser ablation techniques to fabricate membranes and cantilevers made of SiC or nano-(micro-) crystalline diamond films grown on Si/SiO2 substrates by microwave chemical vapour deposition (MWCVD). We started research to generate surface moulds to grow corrugated diamond films for membranes and cantilevers. A software tool was developed to support the design of micromechanical cantilevers. We can measure deformation and resonant frequency of diamond cantilevers and identify the global mechanical properties. A benchmark against finite element simulations enables an inverse identification of the specific system parameters and simplifies the characterization procedure.
Femtosecond laser ablation on Si generates 2D ripple structures, known as laser induced periodic surface structures (LIPSS) and pinholes. We fabricated membranes with 20 to 50 μm thickness perforated by an array of tapered pinholes up to 5 μm in diameter and 10 to 20 μm spacing. Within several micrometer the pinholes transform into hollow photonic waveguides with constant diameter from 1μm to 2μm. Such structures offer a 3D photonic coupling device for polymer Y-branch- and MMI-splitter. We measured a considerable change of electrical resistivity for 500 ppm H2 in air using Si/SiO2/TiO2 substrates with 2D LIPSS. We propose to investigate 3D waveguide arrays also for photonic-chemical sensors.
By a simple femtosecond laser process, we fabricated metal-oxide/gold composite films for electrical and optical gas sensors. We designed a dripple wavelength AWG-spectrometer, matched to the plasma absorption wavelength region of the composite films. H2/CO absorptions fit well with the AWG design for multi gas detection sensor arrays
Black titanium dioxide in situ generated on femtosecond laser induced periodic surface structures
(2018)
Semiconducting metal oxides are widely used for solar cells, poto-catalysis, bio-active materials and gas sensors. Besides the material properties of the used semiconductor,the specific surface topology of the sensor determines the device performance. We investigate the preparation and transfer suitable metals onto LIPPS structures on glass for gas sensing applications.
This thesis evaluates the feasibility of conducting visual inspection tests on power industry constructions using object detection techniques. The introduction provides an overview of this field’s state-of-the-art technologies and approaches. For the implementation, a case study is then conducted, which is done in collaboration with the partner company OMICRON Electronics GmbH, focusing on power transformers as an example. The objective is to develop an inspection test using photographs to identify power transformers and their subcomponents and detect existing rust spots and oil leaks within these components. Three object detection models are trained: one for power transformers and sub-components, one for rust detection, and one for oil leak detection. The training process utilizes the implementation of the YOLOv5 algorithm on a Linux-based workstation with an NVIDIA Quadro RTX 4000 GPU. The power transformer model is trained on a dataset provided by the partner company, while open-source datasets are used for rust and oil leak detection. The study highlights the need for a more powerful GPU to enhance training experiments and utilizes an Azure DevOps Pipeline to optimize the workflow. The performance of the power transformer detection model is satisfactory but influenced by image angles and an imbalance of certain sub-components in the dataset. Multi-angle video footage is a proposed solution for the inspection test to address this limitation and increase the size of the dataset, focusing on reducing the imbalance. The models trained on open-source datasets demonstrate the potential for rust and oil leak detection but lack accuracy due to their generic nature. Therefore, the datasets must be adjusted with case-specific data to achieve the desired accuracy for reliable visual inspection tests. The results of the case study have been well-received by the partner company’s management, indicating future development opportunities. This case study will likely be a foundation for implementing visual inspection tests as a product.
Die schnelllebige und sich verändernde Welt, in der die Menschen gegenwärtig leben, stellt Unternehmen ständig vor neue Herausforderungen. Der Wettbewerb wird immer anspruchsvoller und das Hervorstechen in jeder Branche ist von zahlreichen Faktoren abhängig. Einer davon, der zweifellos einen der grundlegenden Schlüssel zum Erfolg darstellt, ist die Entscheidungsfindung. Um letztere zu unterstützen, werden verschiedene Systeme geschaffen. Unter diesen Systemen lassen sich Business-Analytics-Systeme finden, deren Aufgabe sich auf die Umwandlung von Daten in Informationen konzentriert, um Evidenzen zu schaffen, die es den Managern ermöglicht, Entscheidungen auf der Grundlage von Daten – und nicht auf derjenigen von Intuition – zu treffen. Es ist jedoch Folgendes festzustellen: Obwohl diese Systeme immer besser werden, ist die Mehrheit der Manager in vielen Unternehmen nicht in der Lage, effektive Entscheidungen zu treffen.
Daher ist es das Ziel dieser Arbeit, den Personen in der Wirtschaftswelt eine Untersuchung und Analyse der kognitiven verhaltenspsychologischen Phänomene zur Verfügung zu stellen, um festzulegen, welche dieser Phänomene beim Treffen von Entscheidungen im Rahmen von Business Analytics auftreten und ein Problem verursachen können. Dazu wird die folgende Forschungsfrage gestellt: Welchen Einfluss haben die kognitionspsychologischen Phänomene des Verhaltens in der Business Analytics?
Um diese zu beantworten, ist eine systematische Literaturrecherche durchgeführt worden. Die Analyse der Phänomene anhand eines Data-Mining-Vorgehensmodells (CRISP-DM) zeigte, dass der Einfluss der Phänomene auf Business Analytics signifikant ist und sich auf mehrere Aspekte der Analytik bezieht.
Adult muscle carnitine palmitoyltransferase (CPT) II deficiency is a rare autosomal recessive disorder of long-chain fatty acid metabolism. It is typically associated with recurrent episodes of exercise-induced rhabdomyolysis and myoglobinuria, in most cases caused by a c.338C > T mutation in the CPT2 gene. Here we present the pedigree of one of the largest family studies of CPT II deficiency caused by the c.338C > T mutation, documented so far. The pedigree comprises 24 blood relatives
of the index patient, a 32 year old female with genetically proven CPT II deficiency. In total, the mutation was detected in 20 family members, among them five homozygotes and 15 heterozygotes. Among all homozygotes, first symptoms of CPT II deficiency occurred during childhood. Additionally, two already deceased relatives of the index patient were carriers of at least one copy of the genetic variant, revealing a remarkably high prevalence of the c.338C > T mutation within the tested family. Beside the index patient, only one individual had been diagnosed with CPT II deficiency prior to this study and three cases of CPT II deficiency were newly detected by this family study, pointing
to a general underdiagnosis of the disease. Therefore, this study emphasizes the need to raise awareness of CPT II deficiency for correct diagnosis and accurate management of the disease.