There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

System Identification I

A multidisciplinary approach to understand the interactions of nonthermal plasma and catalyst: A review

Respiratory rate (RR) is an important physiological parameter whose abnormality has been regarded as an important indicator of serious illness. In order to make RR monitoring simple to perform, reliable and accurate, many different methods have been proposed for such automatic monitoring. According to the theory of respiratory rate extraction, methods are categorized into three modalities: extracting RR from other physiological signals, RR measurement based on respiratory movements, and RR measurement based on airflow. The merits and limitations of each method are highlighted and discussed. In addition, current works are summarized to suggest key directions for the development of future RR monitoring methodologies.

https://iopscience.iop.org/article/10.1088/1361-6579/ab299e/pdf

Recent development of respiratory rate measurement technologies

In this paper the Trichel pulse regime of corona discharge in airflows is numerically studied with a two-dimensional model. The model is based on the hydrodynamic drift–diffusion approximation, taking into consideration the flow of the air in the discharge gap. Both transverse and longitudinal airflows under different conditions have been investigated. The influences of airflows on the characteristics of the Trichel pulses were clearly observed and analysed. The simulation results proved to be compatible with experimental analysis reported in the literature.

https://iopscience.iop.org/article/10.1088/0022-3727/46/42/425202/pdf

Numerical studies of Trichel pulses in airflows

In this paper, we analyze the impact of characteristic impedance variations among standards on the accuracy of the thru-reflect-line (TRL) calibration technique. The impedance transformer method is adopted to derive the expressions of the calibration coefficient errors due to the manufacturing tolerances. It is found that three factors can affect the magnitude of the errors in the calibration coefficients (c/a and b terms), which are crucial to get the final calibrated results. The first factor is related to the original parameters of the error networks (test fixtures): the larger the insertion losses, the smaller the error in b ; the error in c/a may see an opposite trend if the error network is lossy instead of lossless. The second factor is denoted as the phase contribution (one of the three multipliers of the derived error expression): the magnitude of this error contributing item is approximately equal to the ratio of two hyperbolic sine functions, the variables of which are the length of Line and the length difference between Line and Thru, respectively. The third factor comes from the impedance differences between Thru and Line: the smaller the impedance variation, the smaller the error. The error analysis, presented here, can help engineers evaluate the calibration accuracy by analyzing the error contributing items. It also can be further used to guide test fixture designs to maximize TRL's error immunity to the transmission line characteristic impedance variations.

Thru-Reflect-Line Calibration Technique: Error Analysis for Characteristic Impedance Variations in the Line Standards

Kalman Filter (KF) is widely used in navigation as a data-fusion algorithm. When KF is applied in high-speed Unmanned Aerial Vehicle (UAV) mounted with low-cost integrated navigation system, its performance always deteriorates in complicated and high-dynamic conditions. Facing such scenario, we proposed a new algorithm of adaptive Kalman Filter in this paper. The new method is based on 1-dimensional Convolutional Neural Network (CNN). The key component of the algorithm is a deep neural network estimator of system noise covariance. We modeled Global Navigation Satellite System (GNSS)/Inertial Navigation System (INS) integrated navigation system and then trained the estimator using IMU and GNSS data which is sampled in real flight. Further, we tested the proposed algorithm on another real-sampled dataset of UAV and compared its performance with classical KF and Sage-Husa adaptive Filter (SHF). The results show a better adaptiveness of the proposed algorithm in high-dynamic condition and partly liberates researchers from parameter tuning.

CNN Based Adaptive Kalman Filter in High-Dynamic Condition for Low-Cost Navigation System on Highspeed UAV

Surface roughness of the conductor in transmission lines will introduce extra losses. The recently proposed Huray model is quite accurate for modeling these additional losses by changing R terms in RLGC models. However, only focusing on the loss modeling of the transmission line may lead to causality issues in time domain simulations. In this paper, the causality requirements of the RLGC models are theoretically analyzed firstly. Then, two solutions of the causality problems in Huray model-based transmission line with rough conductors modeling were proposed and compared. One of them is based on the numerical Hilbert transform, and the other one is analytically based on a complex-valued roughness factor. The causalities of those two solutions are validated by a time domain pulse through a transmission line. The results comparisons of the received pulse responses after the transfer functions show that both methods can improve the causality of the wave propagation term significantly, whereas the analytical solution has better performances and the numerical method has some limitations.

Causality Analyzing for Transmission Line with Surface Roughness

A parallel-plate pair with complex shared antipad structures was analyzed by decomposing it into rectangular local via structures and the plate pair region by virtual interfaces. The rectangle local via structures and the connections between via structures and the plate pair region were rigorously studied. An innovative cavity-based partial-element equivalent-circuit (PEEC) formulation was used to model the rectangle via structures. With special treatment of the reference in the PEEC equivalent circuits, improved circuits model was achieved and all elements of the circuits had clear physical meanings. Furthermore, by enforcing the continuity of the tangential electric fields at the virtual interfaces, the rectangle local via structures were able to connect to the plate region. The impedance parameters of several kinds of rectangle via structures and the whole parallel-plate pair were obtained using the proposed method, and the accuracy of the results was validated with the finite-element solution from a commercial tool.

Lingyun Ye

Papers

Numerical studies of Trichel pulses in airflows

Thru-Reflect-Line Calibration Technique: Error Analysis for Characteristic Impedance Variations in the Line Standards

CNN Based Adaptive Kalman Filter in High-Dynamic Condition for Low-Cost Navigation System on Highspeed UAV

Causality Analyzing for Transmission Line with Surface Roughness

Analyzing Multiple Vias in a Parallel-Plate Pair Based on a Nonorthogonal PEEC Method