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End date: 2021 × Start date: 2021 × DDC: 621.3 × Version: publishedVersion ×

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Now showing 1 - 6 of 6
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    Fast-Slow-Scale Interaction Induced Parallel Resonance and its Suppression in Voltage Source Converters
    (New York, NY : IEEE, 2021) Ma, Rui; Qiu, Qi; Kurths, Jürgen; Zhan, Meng
    Multi-timescale interaction of power electronics devices, including voltage source converter (VSC), has made the stability and analysis of high penetrating renewable power systems very complicated. In this paper, the impedance model is used to analyze the multi-timescale characteristics and interaction of the VSC. Firstly, the multi-timescale impedance characteristics of VSC are investigated based on the Bode plots. It is found that the slow-timescale (within the DC-link voltage control scale) and fast-timescale (within the AC current control scale) models are separately consistent with the full-order model perfectly within their low- and high-frequency ranges. In addition, there exists a high impedance peak within the intermediate frequency range (roughly from 10 Hz to 100 Hz). Then, the impedance peak is theoretically estimated and explained by the slow-fast-scale impedance parallel resonance through transfer-function diagram analysis. Moreover, it is found that the impedance peak is more related to some outer controllers, such as the alternative voltage control and active power control. Specifically, larger proportional coefficients can greatly suppress the resonance peak. Finally, simulations and experiments are conducted to verify the generality of the multi-timescale characteristics and interaction of the VSC. Hence these findings are not only significant to provide a physical insight into the inner key structure of the impedance of VSC, but also expected to be helpful for controller and parameter design of the VSC.
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    Dual-Band Transmitter and Receiver With Bowtie-Antenna in 0.13 μm SiGe BiCMOS for Gas Spectroscopy at 222 - 270 GHz
    (New York, NY : IEEE, 2021) Schmalz, Klaus; Rothbart, Nick; Gluck, Alexandra; Eissa, Mohamed Hussein; Mausolf, Thomas; Turkmen, Esref; Yilmaz, Selahattin Berk; Hubers, Heinz-Wilhelm
    This paper presents a transmitter (TX) and a receiver (RX) with bowtie-antenna and silicon lens for gas spectroscopy at 222-270 GHz, which are fabricated in IHP's 0.13 μm SiGe BiCMOS technology. The TX and RX use two integrated local oscillators for 222 - 256 GHz and 250 - 270 GHz, which are switched for dual-band operation. Due to its directivity of about 27 dBi, the single integrated bowtie-antenna with silicon lens enables an EIRP of about 25 dBm for the TX, and therefore a considerably higher EIRP for the 2-band TX compared to previously reported systems. The double sideband noise temperature of the RX is 20,000 K (18.5 dB noise figure) as measured by the Y-factor method. Absorption spectroscopy of gaseous methanol is used as a measure for the performance of the gas spectroscopy system with TX- and RX-modules.
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    On the Conduction Properties of Vertical GaN n-Channel Trench MISFETs
    ([New York, NY] : IEEE, 2021) Treidel, Eldad Bahat; Hilt, Oliver; Hoffmann, Veit; Brunner, Frank; Bickel, Nicole; Thies, Andreas; Tetzner, Kornelius; Gargouri, Hassan; Huber, Christian; Donimirski, Konstanty; Wurfl, Joachim
    ON-state conductance properties of vertical GaN n -channel trench MISFETs manufactured on different GaN substrates and having different gate trench orientations are studied up to 200 °C ambient temperature. The best performing devices, with a maximum output current above 4 kA/cm 2 and an area specific ON-state resistance of 1.1 mΩ·cm 2 , are manufactured on ammonothermal GaN substrate with the gate channel parallel to the a-plane of the GaN crystal. The scalability of the devices up to 40 mm gate periphery is investigated and demonstrated. It is found that, in addition to oxide interface traps, the semiconductor border traps in the p-GaN layer limit the available mobile channel electrons and that the channel surface roughness scattering limits the channel mobility. Both strongly depend on the gate trench orientation and on the GaN substrate defect density.
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    A TOPSIS-Assisted Feature Selection Scheme and SOM-Based Anomaly Detection for Milling Tools Under Different Operating Conditions
    (New York, NY : IEEE, 2021) Assafo, Maryam; Langendorfer, Peter
    Anomaly detection modeled as a one-class classification is an essential task for tool condition monitoring (TCM) when only the normal data are available. To confront with the real-world settings, it is crucial to take the different operating conditions, e.g., rotation speed, into account when approaching TCM solutions. This work mainly addresses issues related to multi-operating-condition TCM models, namely the varying discriminability of sensory features with different operating conditions; the overlap between normal and anomalous data; and the complex structure of input data. A feature selection scheme is proposed in which the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is presented as a tool to aid the multi-objective selection of sensory features. In addition, four anomaly detection approaches based on Self-Organizing Map (SOM) are studied. To examine the stability of the four approaches, they are applied on different single-operating-condition models. Further, to examine their robustness when dealing with complex data structures, they are applied on multi-operating-condition models. The experimental results using the NASA Milling Data Set showed that all the studied anomaly detection approaches achieved a higher assessment accuracy with our feature selection scheme as compared to the Principal Component Analysis (PCA), Laplacian Score (LS), and extended LS in which we added a final step to the original LS method in order to eliminate redundant features.
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    IEEE Access Special Section Editorial: Recent Advances on Hybrid Complex Networks: Analysis and Control
    (New York, NY : IEEE, 2021) Lu, Jianquan; Ho, Daniel W. C.; Huang, Tingwen; Kurths, Jurgen; Trajkovic, Ljiljana
    Complex networks typically involve multiple disciplines due to network dynamics and their statistical nature. When modeling practical networks, both impulsive effects and logical dynamics have recently attracted increasing attention. Hence, it is of interest and importance to consider hybrid complex networks with impulsive effects and logical dynamics. Relevant research is prevalent in cells, ecology, social systems, and communication engineering. In hybrid complex networks, numerous nodes are coupled through networks and their properties usually lead to complex dynamic behaviors, including discrete and continuous dynamics with finite values of time and state space. Generally, continuous and discrete sections of the systems are described by differential and difference equations, respectively. Logical networks are used to model the systems where time and state space take finite values. Although interesting results have been reported regarding hybrid complex networks, the analysis methods and relevant results could be further improved with respect to conservative impulsive delay inequalities and reproducibility of corresponding stability or synchronization criteria. Therefore, it is necessary to devise effective approaches to improve the analysis method and results dealing with hybrid complex networks.
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    First‐mode of negative streamers: Inception at liquid/solid interfaces
    (Hoboken, NJ : Wiley, 2021) Ariza, David; Beroual, Abderrahmane; Methling, Ralf; Gortschakow, Sergey; Chamorro, Harold R.
    An experimental study of the inception of the first-mode negative streamer at liquid/solid interfaces is presented in this article. The study is performed with a point-plane configuration under square high voltage pulses. The electrode configuration is immersed in mineral oil and the liquid/solid interface is assembled in contact with the point electrode or in its vicinity. Four polymers and two impregnated papers have been tested as solids of the liquid/solid interface. Thus, it is possible to compare the influence of different parameter of the solid and the interface on the streamer inception. For example: Permittivity, solid surface roughness, chemical composition, etc. It has been observed that streamer inception voltages at interfaces with solids of higher permittivity to that of the mineral oil are statistically similar. Additionally, streamer inception voltages of streamer initiated free in the oil (no liquid/solid interface) are similar to that of the inception voltage of cases with solids with high permittivity. In contrast, the inception voltage of streamers initiated at permittivity matched interfaces are shown to be highest of the cases. The streamer inception voltage is also studied for different distances between the liquid/solid interface and the point electrode with a permittivity matched interface. The results show a dependency of the inception voltage and the distance between the point electrode and the interface. Finally, an analysis of the observation is performed to show that the Townsend-Meek criterion cannot predict the obtained results.