A novel point-to-point length measurement concept based on range-resolved interferometry. - In: Engineering for a changing world, (2023), 1.1.099, S. 1-6
In many fields of research and high-value industry, the estimation of distances and displacements is crucial. Due to their extremely high spatial resolution and flexible application possibilities interferometers are cross-sectorally used in measurement practice. However, classical length measuring interferometers are subject to two residual restrictions. On the one hand, only displacements that are exactly aligned to the interferometer optical axis can be measured. On the other hand, deviating refractive indices in the measuring and reference arm due to different atmospheric conditions represent an accuracy-limiting disturbance. In this paper, a new interferometric concept for length measurement is presented. The concept is based on the range-resolved interferometry technology which enables the simultaneous readout and evaluation of two symmetrical interferometric signals which result from the superposition of two non-collimated spherical wavefronts. This allows a point-to-point measurement between two optical fiber ends and the separation of undesired changes of the optical path length outside the measurement cavity and within the measurement cavity.
https://doi.org/10.22032/dbt.58680
Absolute determination of a large mirror surface from spatial gradients using a coordinate measuring machine. - In: Applied Optical Metrology V, (2023), 1267205, S. 1267205-1-1267205-7
This investigation proposes a method for absolute surface determination in a coordinate measuring machine (CMM) with a planar extension of 200 x 200 mm² which is based on the measurement of two spatial gradient fields. The gradient field data was obtained by measuring a test mirror in two equidistant shifted positions along two orthogonal axes while the reference mirror stayed in a steady position. The comparison of experimental data measured in an area of 192 × 192 mm² showed a small root-mean-square deviation of 5.3 nm between the reconstruction result and a regular measurement result. For an a priori estimation of the influence of experimental error sources on the reconstruction deviation, simulations of the measurement process were carried out. Alongside determining the optimal measurement strategy, the focus was investigating positional and orientational deviations of the test surface caused by the shifting motions. While the translational deviations have a subordinate effect, the simulated results show that small orientation deviations around the motion axes cause high reconstruction deviations. To eliminate the motion-induced share of the gradient fields orientation a separation from the topography intrinsic share, which has to remain part of the data, is necessary. This is achieved by the combination of the high-precision design of the mechanical shifting stage and the implementation of an additional boundary condition in the data processing using a least square algorithm.
https://doi.org/10.1117/12.2675734
Investigation on the lithographic process of a high-precision direct laser writing system. - In: Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XX, (2023), 126530A, S. 126530A-1-126530A-7
The semiconductor industry is an unbelievable fast-growing field with an exponential growth in the space optimization. But also, other large industrial field are getting smaller in the structure size, for example the field of optics. On the other hand, the customer demands get more and more complex and individual. This leads to an enormous growth potential for micro- and nanofabrication with direct laser writing. Under this circumstance the idea for a micro- and nanostructuring possibility with high precision on large areas was born. A setup was developed to combine a nanopositioning and nanomeasuring machine (NMM-1) with an extremely high precision and a two-photon based illumination system to realize a high-precision direct laser writing system. Besides its high positioning resolution of 0.1 nm and its metrological traceability based on an interferometrical measurement setup, the NMM-1 offers a positioning range of 25 mm x 25 mm x 5 mm. The aim is to design a direct laser writing setup, which enables a trans-scale fabrication without any stitching or combination of different positioning systems necessary. In order to benefit from this high positional accuracy, studies have been made to investigated the two photon absoption process and reduce line widths. The presented research shows investigations, which were made with the developed laser writing setup, to invested illumination dose and the voxel position of the writing laser, in order to improve microstructuring and to reduce structure widths.
https://doi.org/10.1117/12.2677297
Experimental investigations on the manufacturing of fused silica freeform surfaces by means of fine and ultra-fine grinding. - In: Tenth European Seminar on Precision Optics Manufacturing, (2023), 1275502, S. 1275502-1-1275502-9
The manufacturing of optical freeform surfaces offers a high potential for optical approaches in the future, since they can make new optical systems lighter and more compact or even enable completely new functions, compared to conventional optics. However, the expanded possibilities go hand in hand with higher complexity in production of freeforms for precision optical applications. This leads to high prices and long delivery times. This paper shows an approach to improve manufacturing of freeforms in small batch sizes with a high degree of customization, by a process chain consisting of (ultrasonic-assisted) pre- and fine grinding combined with ultra-fine grinding using resin bond tools. The process chain is suited for efficient fabrication of optical surfaces. A main focus of the experiments is on reduction of low- and mid-spatial frequency surface deviations, as well as surface roughness. Several different influencing factors in a 5-axis CNC grinding process of fused silica freeforms are investigated and their effects on the resulting surface topography (from the low to the high frequency range of surface deviations) are observed using white light interferometry measurement principles. Various optimization approaches can be concluded.
https://doi.org/10.1117/12.2677292
Going one step further: towards cognitively enhanced problem-solving teaming agents. - In: Engineering for a changing world, (2023), 5.1.137, S. 1-12
Operating current advanced production systems, including Cyber-Physical Systems, often requires profound programming skills and configuration knowledge, creating a disconnect between human cognition and system operations. To address this, we suggest developing cognitive algorithms that can simulate and anticipate teaming partners' cognitive processes, enhancing and smoothing collaboration in problem-solving processes. Our proposed solution entails creating a cognitive system that minimizes human cognitive load and stress by developing models reflecting humans individual problem-solving capabilities and potential cognitive states. Further, we aim to devise algorithms that simulate individual decision processes and virtual bargaining procedures that anticipate actions, adjusting the system’s behavior towards efficient goal-oriented outcomes. Future steps include the development of benchmark sets tailored for specific use cases and human-system interactions. We plan to refine and test algorithms for detecting and inferring cognitive states of human partners. This process requires incorporating theoretical approaches and adapting existing algorithms to simulate and predict human cognitive processes of problem-solving with regards to cognitive states. The objective is to develop cognitive and computational models that enable production systems to become equal team members alongside humans in diverse scenarios, paving the way for more efficient, effective goal-oriented solutions.
https://doi.org/10.22032/dbt.58925
A subthreshold second-order integration circuit for versatile synaptic alpha kernel and trace generation. - In: Proceedings of International Conference on Neuromorphic Systems 2023, (2023), 33, insges. 4 S.
In neuromorphic hardware the choice of synaptic kernels and trace dynamics are key for the correct system abstraction and representation of information. This paper presents a novel second-order integration circuit for the implementation of traces and kernels, the Second-order Differential Pair Integrator (SoDPI). It provides smooth alpha-kernel shaped responses to spike input in analog subthreshold complementary Metal Oxide Semiconductor (MOS) technology. Our approach utilises two Differential Pair Integrator (DPI) circuits in series to implement an effective current-mode second-order translinear low-pass filter. Theoretical analysis and experimental measurements demonstrate the improved reliability of this design, which offers a promising approach for modelling biological synaptic and neural responses in neuromorphic hardware, as well as improving the stability of integrated on-chip learning systems.
https://doi.org/10.1145/3589737.3606008
Synaptic normalisation for on-chip learning in analog CMOS Spiking Neural Networks. - In: Proceedings of International Conference on Neuromorphic Systems 2023, (2023), 34, insges. 4 S.
Spiking Neural Networks (SNNs) are becoming increasingly popular for their application in Edge Artificial Intelligence (Edge-AI) due to their sparse and low-latency computation. Among these networks, analog hardware SNNs are chosen for their ability to emulate complex dynamics in neurons and synapses, especially in integrated Metal Oxide Semiconductor (MOS) technology. They can form memories of external stimuli by modulating the strength of synaptic weights. In this context, binary weights are a common hardware design choice, due to their ease to program and store. The use of binary weights in SNNs worsens the bias introduced by the coding level of input stimuli (i.e. fraction of active input nodes), where the network activity is highly correlated to the number of excited neurons. In this paper, we present a Complementary Metal Oxide Semiconductor (CMOS) solution for the coding level bias, by proposing a novel circuit that employs synaptic normalisation at the neuron level. This circuit modifies the gain of the neuron depending on its input weights, with a small footprint and therefore high scalability.
https://doi.org/10.1145/3589737.3606007
Experimental investigation of indoor air ventilation in a small-scale aircraft cabin model. - In: Proceedings of the 5th International Conference on Building Energy and Environment, (2023), S. 1935-1941
The velocity field of the large-scale circulations (LSC) in turbulent mixed convection is analysed by means of 2D2C particle image velocimetry (PIV). The experiments are carried out in a small-scale model room resampling a generic passenger cabin. To achieve wide ranges of dimensionless numbers, pressurized dry air is used in the SCALEX facility. Three different LSCs have been found, depending on the Archimedes number Ar.
https://doi.org/10.1007/978-981-19-9822-5_203
C60 fullerene reduces the level of fluctuations in the force response of muscle gastrocnemius in chronically alcoholized rats. - In: Applied nanoscience, ISSN 2190-5517, Bd. 13 (2023), 10, S. 7057-7067
The biomechanical parameters of muscle gastrocnemius contraction and biochemical parameters of blood and muscle tissue in rats after chronic alcoholization for 3, 6, and 9 months were studied. The oral administration of C60 fullerene aqueous solution (C60FAS) at doses of 0.5, 1, and 2 mg/kg throughout the experiment was used as a therapeutic agent. C60FAS in each of the experimental groups was administered in three ways: 1 h before alcohol intake, together with alcohol, and 1 h after alcohol intake. The most significant positive effects were recorded when alcohol and C60FAS were administered together at the optimal dose of 1 mg/kg. So, the increase in muscle gastrocnemius contraction force was 20 ± 1%, 33 ± 2% and 65 ± 3% (p < 0.05) compared with control at 3, 6, and 9 months alcoholization, respectively, as well as a high level of its fluctuations correction was observed throughout the experiment. Biochemical parameters such as blood levels of creatinine, creatine phosphokinase, lactate and lactate dehydrogenase as well as pro- and antioxidant balance (content of hydrogen peroxide and reduced glutathione, as well as catalase, selenium-dependent glutathione peroxidase and superoxide dismutase activities) in muscle gastrocnemius tissues decreased from 15 ± 2% (3 months of alcoholization) to 45 ± 2% (9 months of alcoholization) (p < 0.05) compared to controls. The results indicate promising prospects for the use of water-soluble C60 fullerenes, as powerful antioxidants, for the correction of pathological conditions of the muscular system arising from alcohol intoxication.
https://doi.org/10.1007/s13204-023-02874-7
Similarity analysis of engineer-to-order parts based on a knowledge graph. - In: 16th CIRP Conference on Intelligent Computation in Manufacturing Engineering, (2023), S. 44-49
By estimating manufacturing costs and times at an early design stage, design of a part and production planning can be improved to significantly reduce product costs. Therefore, a concept for automated estimation of costs and times based on similarity analysis is introduced. This concept is based on a semantic and machine-interpretable representation of part geometries, manufacturing processes and machine capabilities stored in a knowledge graph and uses a semantic distance combined with a numerical distance to compare a new part design with already produced parts. With combined similarity measures and information on manufacturing process steps stored in the knowledge graph, it is possible to estimate the expected manufacturing costs and times.
https://doi.org/10.1016/j.procir.2023.06.009