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Proceedings of the 41st International Conference on Machine Learning

作者： Zalan Fabian Berk Tinaz Mahdi Soltanolkotabi Dept. of Electrical and Computer Engineering University of Southern California Los Angeles CA

Diffusion models have established new state of the art in a multitude of computer vision tasks, including image restoration. Diffusion-based inverse problem solvers generate reconstructions of exceptional visual quality from heavily corrupted measurements. However, in what is widely known as the perception-distortion tradeoff, the price of perceptually appealing reconstructions is often paid in declined distortion metrics, such as PSNR. Distortion metrics measure faithfulness to the observation, a crucial requirement in inverse problems. In this work, we propose a novel framework for inverse problem solving, namely we assume that the observation comes from a stochastic degradation process that gradually degrades and noises the original clean image. We learn to reverse the degradation process in order to recover the clean image. Our technique maintains consistency with the original measurement throughout the reverse process, and allows for great flexibility in trading off perceptual quality for improved distortion metrics and sampling speedup via early-stopping. We demonstrate the efficiency of our method on different high-resolution datasets and inverse problems, achieving great improvements over other state-of-the-art diffusion-based methods with respect to both perceptual and distortion metrics.

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Controlling Age of Information in a Dual-Server System with Transmission Freezing and Preemption

Controlling Age of Information in a Dual-Server System with ...

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IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC)

作者： Nail Akar Sennur Ulukus Electrical and Electronics Engineering Dept. Bilkent University Ankara Turkey Dept. of Electrical and Computer Engineering University of Maryland College Park MD USA

ISBN: (数字)9798350393187

ISBN: (纸本)9798350393194

We study age of information (AoI) in a status update system for the generate-at-will (GAW) scenario, consisting of a single information source, dual heterogeneous servers, and a monitor. For this system, stochastic hybrid systems (SHS) were used to obtain the mean AoI for the work-conserving zero wait (ZW) policy with out-of-order packet discarding at the monitor. In this paper, we propose a non-work-conserving freeze/preempt (F/P) policy for which the sampling and transmission process is frozen for an Erlang-distributed duration upon each new transmission, and out-of-order (obsolete) packets are preempted at the source, rather than being discarded at the monitor upon reception. We use the absorbing Markov chain (AMC) method to obtain the exact distributions of AoI and also the peak AoI (PAoI) processes, for the F/P policy. Numerical results are presented for the validation of the proposed analytical model and a comparative evaluation of ZW and F/P policies.

关键词： Out of order Wireless communication Analytical models Conferences Stochastic processes Signal processing Information age Servers Monitoring

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A DC Link-Based Approach to Realize Zero Feed-in Under Both Static and Dynamic Power System Events

A DC Link-Based Approach to Realize Zero Feed-in Under Both ...

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Compatibility in Power Electronics (CPE)

作者： A. Paspatis B. Adebisi G. Orfanoudakis K. Siderakis E. Karapidakis Nikos Hatziargyriou Dept. of Engineering Manchester Metropolitan University Manchester United Kingdom Dept. of Electrical and Computer Engineering Hellenic Mediterranean University Heraklion Greece School of Electrical and Computer Engineering National Technical University of Athens Athens Greece

ISBN: (数字)9798350318265

ISBN: (纸本)9798350318272

Two factors significantly limiting the increased inter-connection of distributed energy resources in distribution systems are related with the thermal and the short-circuit limits of the primary substations. Even though the zero feed-in approach can address the limitations originating from the thermal limits, the short-circuit limitation issue can not be tackled by this solution. Hence, the short-circuit limitation of primary substations has evolved as the most critical limiting factor in further increasing the distributed energy resources in the distribution system. To address this issue, a novel solution is proposed in this paper, through a DC-link topology that can maintain the zero feed-in conditions of distributed energy resources, during both static and dynamic power system events. The proposed solution is thoroughly described, validated and compared with the conventional zero feed-in approach through simulations in MATLAB/Simulink. It is shown that it can inherently achieve zero current injection to the grid under a short-circuit, while it offers several other advantages, such as fault ride-through and immunity to several grid voltage disturbances.

关键词： Substations Limiting Thermal factors Simulation Power system dynamics Power system stability Distributed power generation

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Modulo-(22n + 1) Arithmetic via Two Parallel n-bit Residue Channels

arXiv

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arXiv 2024年

作者： Jaberipur, Ghassem Nadimi, Bardia Lee, Jeong-A Dept. of Computer Engineering Chosun University Gwangju Korea Republic of Dept. of Computer Science and Engineering University of South Florida TampaFL United States

Augmenting the balanced residue number system moduli-set {m1 = 2n, m2 = 2n − 1, m3 = 2n + 1}, with the co-prime modulo m4 = 22n + 1, increases the dynamic range (DR) by around 70%. The Mersenne form of product m2m3m4 = 24n − 1, in the moduli-set {m1, m2, m3, m4}, leads to a very efficient reverse converter, based on the New Chinese remainder theorem. However, the double bit-width of the m4 residue channel is counter-productive and jeopardizes the speed balance in {m1, m2, m3}. Therefore, we decompose m4 to two complex-number n−bit moduli 2n ± √−1, which preserves the DR and the co-primality across the augmented moduli set. The required forward modulo-(22n + 1) to moduli-(2n ± √−1) conversion, and the reverse are immediate and cost-free. The proposed unified moduli-(2n ± √−1) adder and multiplier, are tested and synthesized using Spartan 7S100 FPGA. The 6−bit look-up tables (LUT), therein, promote the LUT realizations of adders and multipliers, for n = 5, where the DR equals 225 −25. However, the undertaken experiments show that to cover all the 32-bit numbers, the power-of-two channel m1 can be as wide as 12 bits with no harm to the speed balance across_ the five moduli. The results also show that the moduli-(25 ± √−1) add and multiply operations are advantageous vs. moduli-(25 ± 1) in speed, cost, and energy measures and collectively better than those of modulo-(210 + 1). Copyright © 2024, The Authors. All rights reserved.

关键词： Table lookup

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Barrier Function Position-Relative Search Algorithm for Output Voltage Maximization of Inverter-Based Resources

Barrier Function Position-Relative Search Algorithm for Outp...

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Annual North-American Power Symposium

作者： Zachary Towle Visvakumar Aravinthan Dept. of Electrical & Computer Engineering Wichita State University Wichita KS USA

ISBN: (数字)9798331521035

ISBN: (纸本)9798331521042

The push towards better utilization of renewable energy resources in recent years has incentivized the increased injection of power by Inverter-Based Resources (IBR) in electric grids. While the growing number of grid-following (GFL) inverters helps to stabilize the grid, they do come with complications. One of these complications is seen in the lack of ability for inverters to sufficiently provide support to grid voltage profiles during fault events. Creating a generalized model of inverters to effectively predict their behavior during fault events is made difficult by unknown variable grid parameters. This paper will seek to generalize an optimization approach to inverter positive sequence voltage injection by IBRs to effectively support the grid. This will be accomplished by the implementation of an algorithmic barrier function (BF) relative step search scheme used to find extrema in a discontinuous, nonlinear optimization problem. This approach will be developed using MATLAB.

关键词： Renewable energy sources Grid following Voltage Predictive models Search problems Prediction algorithms Mathematical models Inverter-based resource North America Optimization

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Duration-Based Investigation of User Content Choices in the Exit of Filter Bubbles

Duration-Based Investigation of User Content Choices in the ...

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Human-computer Interaction, Optimization and Robotic Applications (HORA), International Congress on

作者： Rabiatu Bunza Dept. of Computer Science Faculty of Science and Engineering Swansea University United Kingdom

ISBN: (数字)9798350394634

ISBN: (纸本)9798350394641

Content personalization on social platforms has been linked to the creation of filter bubbles. The algorithms provide content recommendations based on the user’s browsing history and interests, which limits content diversity. Studies have been conducted on platforms such as Facebook and YouTube to investigate user awareness and strategies to exit filter bubbles. However, no study has employed a multi-platform, user-centered perspective in investigating filter bubble exit through change in search content, as well as the duration of the content transition across multiple platforms. This study examines the duration of user exit of filter bubbles, across three social platforms; TikTok, YouTube Shots, and Instagram Reels, as well as the impact of word similarity on the duration of the transition between contents, across the platforms. The methodology applied involved triggering the filter bubble effect through user interactions with the search content across the different platforms. Findings revealed that the mean time of a transition between search terms on TikTok is significantly higher than the mean time on Instagram reels, and YouTube shorts. Similarly, the study identified differences in the duration of transition across the different platforms, due to the similarity of the search terms. Apart from improving user awareness of a filter bubble exit strategy, this study contributes to Human-computer Interaction research by highlighting some design implications for future social media application design.

关键词： Human computer interaction Video on demand Social networking (online) Psychology Filtering algorithms Web sites Multimedia communication

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Cat-CNN: Human Eye Cataract Detection from Color Fundus Photograph with Deep CNN with Optimized Cascaded Network

Cat-CNN: Human Eye Cataract Detection from Color Fundus Phot...

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IEEE International Conference on Signal Processing, Information, Communication & Systems (SPICSCON)

作者： Md. Sariful Islam Md Tusher Ahmad Bappy Jubayer Ahmed Shawon Mehedi Hasan Wahidur Rahman Lija Akter Mir Mohammad Azad Dept. of Computer Science and Engineering Uttara University Uttara Dhaka Bangladesh Dept. of ICE Bangladesh Army University of Engineering and Technology Natore Bangladesh Dept. of Computer Science and Engineering Inpendent Researcher Dhaka Bangladesh

ISBN: (数字)9798331510213

ISBN: (纸本)9798331510220

Cataracts are clouding of the lens in the eye, leading to loss of vision that can progress to blindness if not treated. This paper proposed a new method for automatic cataract detection using color fundus images and deep learning methods. A dataset of 1,105 color fundus images labeled by expert ophthalmologists was used in this process. We used seven pretrained CNNs (DenseNet121, EfficientNetB0, MobileNetV2, InceptionV3, Xception, ResNet50, VGG16, and VGG19) for feature extraction before reducing the extracted features using PCA. We used the following combination of machine learning classifiers: SVC, RF, Decision Tree, Gaussian Naive Bayes, XGBoost, K-Nearest Neighbors, and Logistic Regression. For evaluating the models' performance, we used accuracy, precision, recall, F1-score, and computational efficiency. For all metrics, MobileNetV2with Random Forest achieved perfect scores: 100% accuracy, precision, recall, and F1-score, with an average processing time of 669 ms ± 28.8 ms. Thus, it can be applied in real-time applications. EfficientNetB0 with SVC gave an average accuracy of 87.33%, with the rest of the precision and recall metrics above 86%. Then, ResNet50, VGG16, and VGG19 followed with high accuracies between the range of 89.64% to 90.50%. It systemizes the proper choice of architectures of CNNs and classifiers, making the system both accurate and computationally efficient. Future work will include augmentation of the dataset, real-time support in the clinical setting, and advanced techniques for image preprocessing, generative adversarial networks. In addition, the development of an automated annotation tool, improvement of explainable AI, will further improve the deployment of robust AI systems in early diagnosis of cataracts, enhancing the outcome for patients.

关键词： Cataracts Measurement Deep learning Accuracy Image color analysis Static VAr compensators Feature extraction Real-time systems Residual neural networks Principal component analysis

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Sparsity Domain Smoothing Based Thresholding Recovery Method for OFDM Sparse Channel Estimation

arXiv

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arXiv 2023年

作者： Bahonar, Mohammad Hossein Zefreh, Reza Ghaderi Amiri, Rouhollah Dept. of Electrical and Computer Engineering Isfahan University of Technology Isfahan Iran Dept. of Electrical and Computer Engineering Sharif University of Technology Tehran Iran

Due to the ever increasing data rate demand of beyond 5G networks and considering the wide range of Orthogonal Frequency Division Multipllexing (OFDM) technique in cellular systems, it is critical to reduce pilot overhead of OFDM systems in order to increase data rate of such systems. Due to sparsity of multipath channels, sparse recovery methods can be exploited to reduce pilot overhead. OFDM pilots are utilized as random samples for channel impulse response estimation. We propose a three-step sparsity recovery algorithm which is based on sparsity domain smoothing. Time domain residue computation, sparsity domain smoothing, and adaptive thresholding sparsifying are the three-steps of the proposed scheme. To the best of our knowledge, the proposed sparsity domain smoothing based thresholding recovery method known as SDS-IMAT has not been used for OFDM sparse channel estimation in the literature. Pilot locations are also derived based on the minimization of the measurement matrix coherence. Numerical results verify that the performance of the proposed scheme outperforms other existing thresholding and greedy recovery methods and has a near-optimal performance. The effectiveness of the proposed scheme is shown in terms of mean square error and bit error rate. © 2023, CC BY.

关键词： Mean square error

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A Medium Voltage Bidirectional Modular LLC Converter With An Extendable Stacked-Switches Leg

A Medium Voltage Bidirectional Modular LLC Converter With An...

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IEEE Energy Conversion Congress and Exposition, ECCE

作者： Maria Beshara Muhammad Ali Masood Cheema John Lam Dept. of Electrical Engineering and Computer Science York University Toronto Canada Northern Transformer Corporation Toronto Canada

ISBN: (数字)9798350376067

ISBN: (纸本)9798350376074

This paper proposes a new stacked-switches/full-bridge (FB) structured DC/DC bidirectional LLC resonant converter for medium voltage DC grids in energy storage application. With the proposed converter configuration, the extendable stacked-switch leg that interfaces with the MV side results in low voltage stress across the switch. In addition, this leg also facilitates rectification in the reverse power flow direction. The proposed converter utilizes variable frequency control to adjust the battery voltage, with FB synchronous rectification to facilitate efficient power flow for both charging and discharging of batteries. The circuit analysis, design considerations, and the operational framework are provided. Results on a 200kW, 100kHz, 10kV/600V design are provided to demonstrate the merits of this work.

关键词： Legged locomotion Switching loss Switches Resonant converters Medium voltage Batteries Voltage control Stress Frequency control Load flow

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Timely Monitoring of Markov Chains Under Sampling Rate Constraints

Timely Monitoring of Markov Chains Under Sampling Rate Const...

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IEEE International Conference on Communications (ICC)

作者： Nail Akar Sennur Ulukus Electrical and Electronics Engineering Dept. Bilkent University Ankara Turkey Dept. of Electrical and Computer Engineering University of Maryland College Park MD USA

ISBN: (数字)9781728190549

ISBN: (纸本)9781728190556

We study a pull-based monitoring system in which a common remote monitor queries the states of a collection of heterogeneous finite-state irreducible continuous time Markov chain (CTMC) based information sources, according to a Poisson process with different per-source sampling rates, in order to maintain remote estimates of the states. Three information freshness models are considered to quantify the accuracy of the remote estimates: fresh when equal (FWE), fresh when sampled (FWS) and fresh when close (FWC). For each of these freshness models, closed-form expressions are derived for mean information freshness for each source, as a function of the sampling rate. Using these expressions, optimum sampling rates for all sources are obtained using water-filling based optimization for maximizing the weighted sum freshness of the monitoring system, under an overall sampling rate constraint. Numerical examples are presented to validate the effectiveness of the proposed method by comparing it to several baseline sampling policies.

关键词： Closed-form solutions Accuracy Computational modeling Numerical models Computational complexity Monitoring Optimization

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