Volumetric Lagrangian temperature and velocity measurements with thermochromic liquid crystals. - In: Measurement science and technology, ISSN 1361-6501, Bd. 35 (2024), 3, 035301, S. 1-11
We propose a Lagrangian method for simultaneous, volumetric temperature and velocity measurements. As tracer particles for both quantities, we employ encapsulated thermochromic liquid crystals (TLCs). We discuss the challenges arising from color imaging of small particles and present measurements in an equilateral hexagonal-shaped convection cell of height h = 60 mm and distance between the parallel side walls w = 10^4 mm, which corresponds to an aspect ratio Γ = 1.73. As fluid, we use a water-glycerol mixture to match the density of the TLC particles. We propose a densely-connected neural network, trained on calibration data, to predict the temperature for individual particles based on their particle image and position in the color camera images, which achieves uncertainties below 0.2 K over a temperature range of 3 K. We use Shake-the-Box to determine the 3D position and velocity of the particles and couple it with our temperature measurement approach. We validate our approach by adjusting a stable temperature stratification and comparing our measured temperatures with the theoretical results. Finally, we apply our approach to thermal convection at Rayleigh number Ra = 3.4 × 10^7 and Prandtl number Pr = 10.6. We can visualize detaching plumes in individual temperature and convective heat transfer snapshots. Furthermore, we demonstrate that our approach allows us to compute statistics of the convective heat transfer and briefly validate our results against the literature.
https://doi.org/10.1088/1361-6501/ad16d1
An integrated approach to developing modular product families in the engineer-to-order sector. - In: Production at the leading edge of technology, (2024), S. 737-746
Nowadays, companies face challenges such as globalization, individualization and shorter product lifecycles, resulting in a constant stream of new product development processes (PDP). Modularized product families represent a powerful concept for reducing complexity and increasing resource efficiency in the PDP and beyond. Despite existing approaches and methods in the development of modular product families, there are deficits in the state of the art regarding their transfer and application to the engineer-to-order (ETO) sector, as well as for neutral indicator-based evaluation. Therefore, this paper derives a generic modularization procedure for the ETO sector and verifies it in an industrial use case. For this purpose, a heuristic swapping algorithm has been developed for grouping the components of a product family into clusters and enabling an objective mathematical evaluation. By integrating modular product structures into organizational processes, ETO manufacturers can strengthen their competitive position as well as increase their resource efficiency.
https://doi.org/10.1007/978-3-031-47394-4_72
Analytical description of transversally symmetric hinges with semicircular contours. - In: Advances in mechanism and machine science, (2024), S. 502-509
Compliant mechanisms are becoming increasingly important, especially in force measurement and weighing technology, due to their zero backlash, wear resistance, and zero friction. Their deformation under external forces can be analyzed well with analytical calculations and FEM simulations. Analytically, only mechanisms with symmetrical and longitudinally symmetrical hinges are described. This paper presents a method that allows transversally symmetric hinges to be described analytically. The model must be computed numerically due to the built neutral fiber and the nonlinearities in the used calculation method. The developed method is then compared with FEM calculations in a parameter study and considered to be validated. Finally, outlooks are formulated on how the created method can for instance be used to develop load cells for later calculations. Moreover, it is shown to what extent it is possible to implement this method for general calculations of compliant mechanisms.
https://doi.org/10.1007/978-3-031-45709-8_49
Shut off! - hybrid BICMOS logic for power-efficient high speed circuits. - In: SMACD 23, (2023), insges. 4 S.
Power efficiency is crucial, especially in high-speed systems, where conventional approaches like clock gating cannot be employed readily. Special logic families, such as Positive Emitter-Coupled Logic (PECL), push the technological frontier, promising even more speed at the expense of an even more strained power budget. We propose a novel hybrid of PECL and Complementary Metal-Oxide-Semiconductor (CMOS) logic to introduce Function Shut-off (FSO), realizing a shut-off at the level of functional blocks and logic primitives inside complex logic cells. Using this approach, we realize a high-speed Linear Feedback Shift Register (LFSR) in a SiGe technology, extending the State of the Art (SOTA) by adding reconfigurability, which is required for its use as sequence generator in Compressed Sensing (CS) applications. We present measurements showing successful fabrication and performance of the packaged die at 20.4 GHz. In this LFSR, employing FSO reduces the supply current by a factor of up to four (depending on the chosen configuration) and reduces active area by 17%.
https://doi.org/10.1109/SMACD58065.2023.10192217
Robust spiking attractor networks with a hard Winner-Take-All neuron circuit. - In: IEEE ISCAS 2023 symposium proceedings, (2023), insges. 5 S.
Attractor networks are widely understood to be a re-occurring primitive that underlies cognitive function. Stabilising activity in spiking attractor networks however remains a difficult task, especially when implemented in analog integrated circuits (aIC). We introduce here a novel circuit implementation of a hard Winner-Take-All (hWTA) mechanism, in which competing neurons' refractory circuits are coupled together, and thus their spiking is forced to be mutually exclusive. We demonstrate stable persistent-firing attractor dynamics in a small on-chip network consisting of hWTA-connected neurons and excitatory recurrent synapses. Its utility within larger networks is demonstrated in simulation, and shown to support overlapping attractors and be robust to synaptic weight mismatch. The realised hWTA mechanism is thus useful for stabilising activity in spiking networks composed of unreliable components, without the need for careful parameter tuning.
https://doi.org/10.1109/ISCAS46773.2023.10181513
Modulating functions analysis for wireless data transmission because of advanced sensors in energy-saving process of washing. - In: Renewable energy & power quality journal, ISSN 2172-038X, Bd. 21 (2023), 6, S. 695-700
The vibration measurement of flows in transient or steady-state is a very complicated task. Moreover, to correlate it with a temperature process is quite important according to get information regarding molecular kinetic energy of thermal sources (such as flow measurement used in cleaning tasks) according to achieve heating transfer information of a thermal process. However, there is a trouble concerning the transduction stage in the measurement while it is not a transducer designed algorithm as a consequence of a mathematical model, which correlates the calibration data with the theoretical model of the heating/vibration transfer. For this reason, in this research is proposed intelligent sensors/transducers, which are based on Anodic Aluminium Oxide (AAO) and a mathematical procedure of the measurement instrumentation according to adaptive coefficients in the Modulating Functions strategies analysis and getting optimal measurements. In this research is explained and analysed the temperature measurement process and the transduction process as the strict correlation of the calibration of the temperature/vibration sensor. For this reason, there were evaluated different transducers and the temperature/vibration reference for the calibration. The based on nanostructures temperature sensors are designed by specific and complex procedures according to achieve quite operation range, robustness and precision. Moreover, the transduction can be obtained through different electrical answer variables such as voltage, electrical current or capacitance and possible to send by wireless mechanisms and protocols to the main control system. Therefore, the evaluation of the designed advanced sensor performance was achieved by the vibration and temperature measurement of the water surface of a ultrasound washing machine, for which the designed sensor enhances energy-saving of the washing process.
https://doi.org/10.24084/repqj21.453
Assembly and packaging technology on Silicon-Ceramic-based composite substrates. - In: 2023 International Conference on Electronics Packaging (ICEP), (2023), S. 49-50
A novel silicon-ceramic composite substrate enables the combination of both materials through one sinter process. Due to the customized manufactured ceramic tapes an examination of available metallization pastes for solder and wire bond applications on this new material system is required. The goal for this investigation is the replacement of currently two application specific metallization pastes (AuPt for soldering and Au for wire bonding) to one paste (Ag) for both applications, which results in a simplifying of the manufacturing process and reducing the production costs.
https://doi.org/10.23919/ICEP58572.2023.10129654
Characterization of propagation in an industrial scenario from sub-6 GHz to 300 GHz. - In: IEEE Xplore digital library, ISSN 2473-2001, (2023), S. 1475-1480
We perform simultaneous multi-band ultra-wideband dual-polarized double-directional measurements at sub-6 GHz (center frequency, 6.75 GHz), mmWave (74.25 GHz), and sub-THz (305.27 GHz) in line of sight (LOS) and non-LOS in a small industrial scenario (machine room). The aim is to characterize the propagation at THz taking as a reference the lower bands and identifying shared and distinguishing features. The spatial/temporal analysis of the measurements shows strong similarities in multi-path components (MPCs) between the different bands. Moreover, high order reflections have been identified at THz. Overall, the results indicate that THz channels exhibit significant multipath, with some specular MPCs unique to the band and with lower contribution by the diffuse components. Finally, path-loss has also been computed and compared with existing multi-band models.
https://doi.org/10.1109/GCWkshps58843.2023.10464485
Shadow masks as an alternative method to lithography for the structuring of thin film layers on LTCC substrates. - In: IMAPSource proceedings, ISSN 2380-4505, Bd. 2023 (2023), HiTEC, CICMT, Power, S. 1-4
The combination of low temperature cofired ceramic multilayer technology with thin film deposition methods enables new functional principles by expanding the available portfolio of materials. Low-stress integration of micromechanical chips can be achieved, for example, by using reactive multilayers as local heat sources, which can be deposited directly onto the ceramics. Shadow masks are ideal for structuring these multilayers. The technology has the advantage that the layers are patterned without the use of etching chemicals and no residues of masking layers or photoresist remain on the non-coated areas. Flexible polyimide used to cover the non-coated areas can adapt to the surface unevenness of the ceramic. The polymer has excellent temperature stability and is compatible with vacuum coating processes. It is available in various thickness gradations and can be easily structured by laser cutting. The accuracy of the mask fabrication by means of laser cut is studied in this work. Structures with a line width of 30 μm can be precisely cut into 75 μm thick polyimide foils. Mask and chip are mechanically aligned, thus a positioning accuracy of 70 μm and better when using the outer edge of mask and chip for alignment is achievable. Major influences of the laser process on the precision of the mask and the resulting transfer fidelity to the ceramic surface are discussed. The method is suitable for reliably reproducing layers with structure sizes from 30 μm with a pitch of 150 μm.
https://doi.org/10.4071/001c.89092
Innovative silicon-ceramic (SiCer) technology for high-strength pressure sensor applications using different manufacturing methods. - In: 24th European Microelectronics & Packaging Conference (EMPC 2023), (2023), S. 1-6
A variety of manufacturing methods can be used to assemble silicon-based piezoresistive pressure sensors, such as anodic bonding or silicon direct bonding. To achieve high-strength pressure sensors, a high quality interface connection is required. The combination of silicon and ceramic creates a new innovative composite system known as Silicon-on-Ceramics, short SiCer. By using a special developed bondable Low Temperature Co-fired Ceramic tape, which corresponds to the thermal expansion coefficient of Si, the combination of both materials is possible through a sintering process. Advantages of the SiCer technology are high temperature stability, manufacturing at wafer-level and a high bond strength at the interface. Different manufactured SiCer-based pressure sensors were fabricated, electrically and mechanically characterized and compared with anodic bonded and silicon direct bonded pressure sensors.
https://doi.org/10.23919/EMPC55870.2023.10418331