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A Silicon Micromachined Sub-THz Waveguide with Etch Holes

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A Silicon Micromachined Sub-THz Waveguide with Etch Holes

Asia-Pacific Conference on Microwave

作者： Xinghai Zhao Yu Wen Oleksandr Glubokov School of Electrical and Electronic Engineering Nanyang Technological University Singapore School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm Sweden Folkuniversitetet Umeå Umeå Sweden Division of Micro- and Nanosystems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm Sweden

ISBN: (数字)9798350363548

ISBN: (纸本)9798350363555

This paper explores the impact of etch holes on sub-terahertz (THz) waveguide transmission performance and presents a silicon micromachined WR-03 waveguide with etch holes. The influence of etch-hole size and grid size is investigated through simulations. The waveguide prototype is realized through deep reactive ion etching (DRIE) and low-temperature thermal-compression bonding. Measurements reveal a low transmission loss (average 0.04 dB/mm) for the etched waveguide, with negligible influence on transmission loss observed for etch hole sizes below a specific threshold, which agrees with the simulations. The findings guide the design and optimization of micromachined THz waveguide components with etch holes applied in some specific situations.

关键词： Performance evaluation Microwave measurement Waveguide components Prototypes Propagation losses Size measurement Silicon Loss measurement Optimization Microwave propagation

Weighted Null Space Fitting (WNSF): A Link between The Prediction Error Method and Subspace Identification

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arXiv 2024年

作者： He, Jiabao Hjalmarsson, Håkan Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm100 44 Sweden

— Subspace identification method (SIM) has been proven to be very useful and numerically robust for estimating state-space models. However, it is in general not believed to be as accurate as prediction error method (PEM). Conversely, PEM, although more accurate, comes with non-convex optimization problems and requires local non-linear optimization algorithms and good initialization points. This contribution proposes a weighted null space fitting (WNSF) method to identify a state-space model, combining some advantages of the two mainstream approaches aforementioned. It starts with the estimate of a nonparametric model using least-squares, and then the reduction to a state-space model in the observer canonical form is a multi-step least-squares procedure where each step consists of the solution of a quadratic optimization problem. Unlike SIM, which focuses on the range space of the extended observability matrix, WNSF estimates its null space, avoiding the need for singular value decomposition. Moreover, the statistically optimal weighting for the null space fitting problem is derived. It is conjectured that WNSF is asymptotically efficient, which is supported by a simulation study. Copyright © 2024, The Authors. All rights reserved.

关键词： State space methods

Finding Control Invariant Sets via Lipschitz Constants of Linear Programs

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arXiv 2024年

作者： Vahs, Matti Han, Shaohang Tumova, Jana Division of Robotics Perception and Learning School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm Sweden Digital Futures

Control invariant sets play an important role in safety-critical control and find broad application in numerous fields such as obstacle avoidance for mobile robots. However, finding valid control invariant sets of dynamical systems under input limitations is notoriously difficult. We present an approach to safely expand an initial set while always guaranteeing that the set is control invariant. Specifically, we define an expansion law for the boundary of a set and check for control invariance using Linear Programs (LPs). To verify control invariance on a continuous domain, we leverage recently proposed Lipschitz constants of LPs to transform the problem of continuous verification into a finite number of LPs. Using concepts from differentiable optimization, we derive the safe expansion law of the control invariant set and show how it can be interpreted as a second invariance problem in the space of possible boundaries. Finally, we show how the obtained set can be used to obtain a minimally invasive safety filter in a Control Barrier Function (CBF) framework. Our work is supported by theoretical results as well as numerical examples. Copyright © 2024, The Authors. All rights reserved.

关键词： Collision avoidance

Self-Immolative Electrochemical Redox Substrates: Emerging Artificial Receptors in Sensing and Biosensing

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ACS Measurement science Au 2024年第2期4卷 163-183页

作者： Manibalan, Kesavan Arul, Ponnusamy Wu, Hsin-Jay Huang, Sheng-Tung Mani, Veerappan Department of Materials Science and Engineering National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan Institute of Biochemical and Biomedical Engineering Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei 10608 Taiwan Advanced Membranes and Porous Materials Center (AMPMC) Computer Electrical and Mathematical Science and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia High-Value Biomaterials Research and Commercialization Center National Taipei University of Technology No. 1 Sec. 3 Zhongxiao E. Rd. Taipei 10608 Taiwan

The development of artificial receptors has great significance in measurement science and technology. The need for a robust version of natural receptors is getting increased attention because the cost of natural receptors is still high along with storage difficulties. Aptamers, imprinted polymers, and nanozymes are some of the matured artificial receptors in analytical chemistry. Recently, a new direction has been discovered by organic chemists, who can synthesize robust, activity-based, self-immolative organic molecules that have artificial receptor properties for the targeted analytes. Specifically designed trigger moieties implant selectivity and sensitivity. These latent electrochemical redox substrates are highly stable, mass-producible, inexpensive, and eco-friendly. Combining redox substrates with the merits of electrochemical techniques is a good opportunity to establish a new direction in artificial receptors. This Review provides an overview of electrochemical redox substrate design, anatomy, benefits, and biosensing potential. A proper understanding of molecular design can lead to the development of a library of novel self-immolative redox molecules that would have huge implications for measurement science and technology. © 2024 The Authors. Published by American Chemical Society.

关键词： alkaline phosphatase artificial receptors electrochemical mediators electrochemical sensors and biosensors galactosidase hydrogen peroxide neuraminidase organic electrochemistry ratiometric sensors self-immolative sensors

Time-Invariant Beampattern Design in Frequency Diverse Array Radar: Some New Results

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Time-Invariant Beampattern Design in Frequency Diverse Array...

Digital Futures and Transformative Technologies (ICoDT2), International Conference on

作者： Shaiza Obaidullah Ahmed Hussain Ali Alam Zaib Sajid Ahmed School of Electrical Engineering and Computer Science National University of Sciences and Technology Islamabad Pakistan Department of Electrical Engineering Military College of Signals National University of Sciences and Technology Islamabad Pakistan Department of Electrical and Computer Engineering COMSATS University Islamabad Abbottabad Islamabad Pakistan Computer Electrical and Mathematical Sciences and Engineering Division King Abdullah University of Science and Technology Thuwal Saudi Arabia

ISBN: (数字)9798350391862

ISBN: (纸本)9798350391879

A new frequency diverse array (FDA) radar system is proposed for range estimation of a target using time-invariant beampattern. To illuminate a desired range, the transmit beampattern is optimized using the inverse fast Fourier transform (IFFT) technique. This allows for a longer dwell period, which improves the accuracy of weak target identification. To lessen noise effects in range estimation, the minimum power distortionless response (MPDR) beamformer is employed. The precision of range estimation is derived using the Cramér-Rao lower bound (CRLB). Based on simulation data, the FDA design that has been proposed performs better than current approaches as measured by the root-mean-squared error (RMSE). The proposed FDA radar shows superior target localization performance compared to existing techniques, achieving the CRLB at a signal-to-noise (SNR) value of −5 dB.

关键词： Location awareness Time-frequency analysis Fast Fourier transforms Measurement uncertainty Estimation Radar Frequency estimation Frequency diversity Distortion measurement Signal to noise ratio

Dissipative Avoidance Feedback for Reactive Navigation Under Second-Order Dynamics

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arXiv 2024年

作者： Smaili, Lyes Tang, Zhiqi Berkane, Soulaimane Hamel, Tarek Department of Computer Science and Engineering University of Quebec in Outaouais GatineauQC Canada Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology StockholmSE-10044 Sweden Department of Electrical Engineering Lakehead University ON Canada France

This paper addresses the problem of autonomous robot navigation in unknown, obstacle-filled environments with second-order dynamics by proposing a Dissipative Avoidance Feedback (DAF). Compared to the Artificial Potential Field (APF), which primarily uses repulsive forces based on position, DAF employs a dissipative feedback mechanism that accounts for both position and velocity, contributing to smoother and more natural obstacle avoidance. The proposed continuously differentiable controller solves the motion-to-goal problem while guaranteeing collision-free navigation by using the robot’s state and local obstacle distance information. We show that the controller guarantees safe navigation in generic n-dimensional environments and that all undesired ω-limit points are unstable under certain controlled curvature conditions. Designed for real-time implementation, DAF requires only locally measured data from limited-range sensors (e.g., LiDAR, depth cameras), making it particularly effective for robots navigating unknown workspaces. Simulations in 2D and 3D environments are conducted to validate the theoretical results and to showcase the effectiveness of our approach. © 2024, CC BY.

关键词： Feedback

Weighted Least-Squares PARSIM

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arXiv 2024年

作者： He, Jiabao Rojas, Cristian R. Hjalmarsson, Håkan Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm100 44 Sweden

Subspace identification methods (SIMs) have proven very powerful for estimating linear state-space models. To overcome the deficiencies of classical SIMs, a significant number of algorithms has appeared over the last two decades, where most of them involve a common intermediate step, that is to estimate the range space of the extended observability matrix. In this contribution, an optimized version of the parallel and parsimonious SIM (PARSIM), PARSIMopt, is proposed by using weighted least-squares. It not only inherits all the benefits of PARSIM but also attains the best linear unbiased estimator for the above intermediate step. Furthermore, inspired by SIMs based on the predictor form, consistent estimates of the optimal weighting matrix for weighted least-squares are derived. Essential similarities, differences and simulated comparisons of some key SIMs related to our method are also presented. Copyright © 2024, The Authors. All rights reserved.

关键词： State space methods

Coherence-based Input Design for Sparse System Identification

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arXiv 2024年

作者： Parsa, Javad Rojas, Cristian R. Hjalmarsson, Håkan Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm100 44 Sweden

The maximum absolute correlation between regressors, which is called mutual coherence, plays an essential role in sparse estimation. A regressor matrix whose columns are highly correlated may result from optimal input design, since there is no constraint on the mutual coherence, so when this regressor is used to estimate sparse parameter vectors of a system, it may yield a large estimation error. This paper aims to tackle this issue for fixed denominator models, which include Laguerre, Kautz, and generalized orthonormal basis function expansion models, for example. The paper proposes an optimal input design method where the achieved Fisher information matrix is fitted to the desired Fisher matrix, together with a coordinate transformation designed to make the regressors in the transformed coordinates have low mutual coherence. The method can be used together with any sparse estimation method and in a numerical study we show its potential for alleviating the problem of model order selection when used in conjunction with, for example, classical methods such as AIC and BIC. © 2024, CC BY.

关键词： Fisher information matrix

On final opinions of the Friedkin-Johnsen model over random graphs with partially stubborn community

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On final opinions of the Friedkin-Johnsen model over random ...

IEEE Conference on Decision and Control

作者： Lingfei Wang Yu Xing Karl H. Johansson Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology and with Digital Futures Stockholm Sweden

ISBN: (数字)9798350316339

ISBN: (纸本)9798350316346

This paper studies the formation of final opinions for the Friedkin-Johnsen (FJ) model with a community of partially stubborn agents. The underlying network of the FJ model is symmetric and generated from a random graph model, in which each link is added independently from a Bernoulli distribution. It is shown that the final opinions of the FJ model will concentrate around those of an FJ model over the expected graph as the network size grows, on the condition that the stubborn agents are well connected to other agents. Probability bounds are proposed for the distance between these two final opinion vectors, respectively for the cases where there exist non-stubborn agents or not. Numerical experiments are provided to illustrate the theoretical findings. The simulation shows that, in presence of non-stubborn agents, the link probability between the stubborn and the non-stubborn communities affect the distance between the two final opinion vectors significantly. Additionally, if all agents are stubborn, the opinion distance decreases with the agent stubbornness.

关键词： Vectors Numerical models