Reliability study of Ag through via interconnects for integrated horn antennas in LTCC substrates. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), S. 281-282
This contribution investigates various Ag pastes for through via interconnect application to produce an integrated horn antenna structure in Low Temperature Cofired Ceramic (L TCC) material. In a two-stage experimental process, the Ag pastes are first limited using a simplified test layout to identify promising pastes for further investigation in the second phase with a more complex design. The electrical contact is verified using the implemented daisy chain. X-ray examinations and cross-sections are performed to assess the quality and quantity of the via fill results.
https://doi.org/10.23919/ICEP61562.2024.10535536
Surface manipulation of Ag metallization to improve the adhesion strength for soldering applications on LTCC. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), S. 209-210
This study verifies a Low Temperature Cofired Ceramic (LTCC) material with excellent properties for radar antennas and assembly purposes. Various surface manipulation techniques are examined on thick-film printed co- and postfired Ag metallization to increase the bond strength of solder joints on two customized LTCC materials. Modified surfaces are analyzed and compared with unmodified solder pads. Both LTCCs are electrically characterized and used for simulation with a view to using silicon-ceramic technology for 79 GHz radar antennas.
https://doi.org/10.23919/ICEP61562.2024.10535677
Supporting circular economy strategies for design of sustainable mechatronic systems using MBSE. - In: Proceedings of the Design Society, ISSN 2732-527X, Bd. 4 (2024), S. 2645-2654
The paper investigates approaches for implementing circular economy strategies, such as designing mechatronic products for longer service life by replacing, upgrading, or remanufacturing subsystems. The research aims at applying MBSE to provide the necessary support for dealing with the complexity of these approaches. Requirements and challenges for the development of MBSE support in this context are examined. An example of an EV battery system model shows the benefits and challenges of comprehensive system modelling and traceability in the context of circular economy strategies.
https://doi.org/10.1017/pds.2024.267
Updates on the new Kibble balance at NIST. - In: ASPE Annual Meeting 2023, (2024), S. 194-195
Introduction and application of a new approach for model-based optical bidirectional measurements. - In: Measurement science and technology, ISSN 1361-6501, Bd. 35 (2024), 8, 085014, S. 1-10
Accurate measurements of micro- and nanoscale features in optical microscopy demand comprehensive modelling approaches. In this study, we introduce an enhanced evaluation method, utilizing rigorous simulations based on a finite element method algorithm within an advanced Bayesian optimization framework. We provide an in-depth explanation of the measurement process, including the dimension reduction techniques applied to the acquired measurement data. Additionally, we employ Hopkins’ approximation or also referred to as local Hopkins’ methods for an efficient microscopic image simulation, resulting in a significant reduction of the computing time. We applied this method to measure the linewidths of six different chrome lines, nominally 300 nm-1000 nm wide, on a glass substrate. Our results show an excellent agreement with previous investigations conducted using various measurement systems, including atomic force microscopy, scanning electron microscopy, and optical microscopy in combination with different measurement evaluation techniques.
https://doi.org/10.1088/1361-6501/ad4b53
Formation of voids due to transitions in permeability and cavity diameter during resin injection processes. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 3012 (2024), 1, 020013, S. 020013-1-020013-9
The specific mechanical properties of fiber reinforced composite components are unmatched, considering their low weight. To optimize the lightweight potential of fiber reinforced composites, fiber volume contents have to be maximized and imperfections must be eliminated. However, during the production of fiber reinforced composite laminates via resin injection processes, the formation of microscopic voids is nearly inevitable. Even low amounts of imperfections can cause significant deteriorations in the mechanical properties of the material. To reduce the number of voids inside composite components, understanding the formation and transport of voids is essential. Numerous renowned models describe said formation of voids in dependence of local flow front conditions during the impregnation of textile preforms with thermoset resins. State of the art are models emphasizing the formation of meso-and microvoids in dependence of the modified capillary number. These models show plausible correlations when applied to unidirectional preforms or fabrics with constant permeability along the direction of flow. However, the formation of voids remains to be investigated at points of transitioning permeability, such as alterations in the setup of layers or abruptly changing cavity diameters. To expand the applicability of the existing models onto preforms with local changes in permeability, an experimental setup for gradually increasing cavity diameter and varying layer setup is introduced. A planar mold with three increasing levels of cavity height is used to induce changes in permeability. The rate of change in permeability is controlled by defining the slope between each level. In this study, injection pressure as well as flow front velocity were optically traced, and material data was measured. Resulting local void volume contents were quantified by calcination. It is demonstrated how alterations of diameter and layup take effect on the resulting local porosity. The observed impact on void formation is put in context to changes in tow permeability due to local differences in fiber volume content. By including the slope dependent rate of change in tow permeability into the existing model for calculation of void formation by GUEROULT ET AL., the accuracy of the model can be increased. Comparing the unaltered model to experimental results, the deviations between calculations and measurements were diminished when using the newly introduced factors. Although the error of prediction is being significantly reduced, calculations are still flawed since additional effects like overflow at level edges need to be considered. This discourse is meant to administer a starting point for considering rates of change in tow permeability into the commonly established use of shape factors of models of void formation.
https://doi.org/10.1063/5.0194324
Investigations on tip-based large area nanofabrication and nanometrology using a planar nanopositioning machine (NFM-100). - In: Measurement science and technology, ISSN 1361-6501, Bd. 35 (2024), 8, 085011, S. 1-14
This paper explores large area application of tip-based nanofabrication by field emission scanning probe lithography and showcases the simultaneous possibility of atomic force microscopy on macroscopic scales. This is made possible by the combination of tip-based technology and a planar nanopositioning and nanomeasuring machine. Using long range atomic force microscopy measurement of regular grating structures, the performance of the machine is thoroughly characterized over the full 100 mm range of motion of the positioning machine, which was confirmed by repeated measurements. After initially focussing on achieving the minimum line width of 40 nm in microscopic areas, a grating with a pitch of 1 μm is additionally fabricated over a total length of 10 mm, whereby the dimensions and deviations are also considered.
https://doi.org/10.1088/1361-6501/ad4668
Improving the spatial correlation characteristics of antenna arrays using linear operators and wide-band modelling. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), S. 67-73
The analysis of wireless communication channels at the mmWave, sub-THz and THz bands gives rise to difficulties in the construction of antenna arrays due to the small maximum inter-element spacing constraints at these frequencies. Arrays with uniform spacing greater than half the wavelength for a certain carrier frequency exhibit aliasing side-lobes in the angular domain, prohibiting non-ambiguous estimates of a propagating wave-front’s angle of arrival.In this paper, we present how wide-band modelling of the array response is useful in mitigating this spatial aliasing effect. This approach aims to reduce the grating lobes by exploiting the angle- and frequency-dependent phase-shifts observed in the response of the array to a planar wave-front travelling across it.Furthermore, we propose a method by which the spatial correlation characteristics of an array operating at 33 GHz carrier frequency with an instantaneous bandwidth of 1 GHz can be improved such that the angular-domain side-lobes are reduced by 5-10 dB. This method, applicable to arbitrary antenna array manifolds, makes use of a linear operator that is applied to the base-band samples of the channel transfer function measured in space and frequency domains. By means of synthetically simulated arrays, we show that when operating with a bandwidth of 1 GHz, the use of a derived linear operator applied to the array output results in the spatial correlation characteristics approaching those of the array operating at a bandwidth of 12 GHz. Hence, non-ambiguous angle estimates can be obtained in the field without the use of expensive high-bandwidth RF front-end components.
https://doi.org/10.1109/WSA61681.2024.10511328
Integrated chassis control for energy-efficient operation of a 2WD battery-electric vehicle with in-wheel propulsion. - In: SAE technical papers, ISSN 2688-3627, (2024), SAE technical paper 2024-01-2550, S. 1-9
Battery-electric vehicles (BEVs) require new chassis components, which are realized as mechatronic systems mainly and support more and more by-wire functionality. Besides better controllability, it eases the implementation of integrated control strategies to combine different domains of vehicle dynamics. Especially powertrain layouts based on electric in-wheel machines (IWMs) require such an integrated approach to unfold their full potential. The present study describes an integrated, longitudinal vehicle dynamics control strategy for a battery electric sport utility vehicle (SUV) with an electric rear axle based on in-wheel propulsion. Especially the influence of electronic brake force distribution (EBD) and torque blending control on the overall performance are discussed and demonstrated through experiments and driving cycles on public road and benchmarked to results of previous studies derived from [1]. It is shown that the approach improves energy efficiency and energy recovery potential by nearly ten per cent.
https://doi.org/10.4271/2024-01-2550
Improving vehicle stability and comfort through active corner positioning. - In: SAE technical papers, ISSN 2688-3627, (2024), SAE technical paper 2024-01-2552, S. 1-9
The emergence of new electric vehicle (EV) corner concepts with in-wheel motors offers numerous opportunities to improve handling, comfort, and stability. This study investigates the potential of controlling the vehicle's corner positioning by changing wheel toe and camber angles. A high-fidelity simulation environment was used to evaluate the proposed solution. The effects of the placement of the corresponding actuators and the actuation point on the force required during cornering were investigated. The results demonstrate that the toe angle, compared to the camber angle, offers more effect for improving the vehicle dynamics. The developed direct yaw rate control with four toe actuators improves stability, has a positive effect on comfort, and contributes to the development of new active corner architectures for electric and automated vehicles.
https://doi.org/10.4271/2024-01-2552