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A K -Band Four-Beam Transmitter with Decoupled Phase/Gain Control and Enhanced Power Back off Efficiency for SATCOM

IEEE Transactions on Microwave Theory and Techniques 2024年第11期72卷 6443-6459页

作者： Gao, Huiyan Li, Nayu Xie, Xinhong Wang, Shaogang Lu, Hang Kuan, Yen-Cheng Yu, Xiaopeng Song, Chunyi Jane Gu, Qun Xu, Zhiwei Institute of Marine Electronics and Intelligent Systems Ocean College Zhejiang University Zhoushan316021 China Engineering Research Center of Oceanic Sensing Technology and Equipment Ministry of Education Zhoushan316021 China Donghai Laboratory Zhoushan316021 China National Yang Ming Chiao Tung University International College of Semiconductor Technology Hsinchu30010 Taiwan Institute of VLSI Design and Research College of Information Science and Electronic Engineering Zhejiang University Hangzhou310058 China University of California at Davis Department of Electrical and Computer Engineering DavisCA95616 United States

This article presents a 17.7-20.2 GHz eight-element four-beam RF-beamforming transmitter in 65-nm CMOS for satellite communication (SATCOM). The transmitter utilizes an analog scheme in the variable-gain amplifier (VGA) to achieve dB-in-linear gain control with a high dynamic range (DR), together with a current combining crossbar for a compact footprint. The vector-modulation-based (VM-based) phase shifter (PS) adopts the cancellation-based Gm units for low switching variation. Furthermore, eight PSs of each beam are split into two groups, with each group sharing the same tunable I/Q generator for low power consumption. Considering the increased peak-to-average power ratio (PAPR) caused by high-order modulation schemes and multibeam operation, the transmitter incorporates compact transformer-based Doherty power amplifiers (DPAs) with adaptive bias control to improve the power efficiency at back-off. The chip achieves a 31-dB gain-tuning range with a 0.283-dB step and a 360° phase-shifting range with a calibrated 7-bit resolution. The measured root-mean-square (RMS) phase/gain errors induced by the VGA/PS are below 2.05°/0.147 dB, respectively, which decouples phase/gain control. The transmitter achieves a maximum output 1-dB gain compression point (OP1dB) of 17.9 dBm and a maximum saturated power (Psat) of 18.9 dBm. The output element exhibits 29.3% drain efficiency (DE) at 6-dB power back off (PBO) from Psat , which is 1.56/3.12 times over the normalized class-B/class-A implementations, demonstrating Doherty PBO efficiency enhancement. The chip occupies an area of 8.59 × 4.17 mm2 and consumes 398 mW per element at OP1dB. Additionally, a 16-element linear array has been developed to showcase the capabilities of the multibeam operation and gain tapering. © 1963-2012 IEEE.

关键词： Efficiency

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Pump-Controlled Mode-Locking Switching in an All-Polarization-Maintaining Fiber Laser

Pump-Controlled Mode-Locking Switching in an All-Polarizatio...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Maolin Dai Bowen Liu Guanyu Ye Yifan Ma Naoki Yamaguchi Takuma Shirahata Sze Yun Set Shinji Yamashita Department of Electrical Engineering and Information Systems University of Tokyo Tokyo Japan Research Center for Advanced Science and Technology University of Tokyo Tokyo Japan

We demonstrate the pump-controlled mode-locking switching in an all-polarization-maintaining, CNT-mode-locked fiber laser. By simply changing the injected pump power, the mode-locking can be switched between two wavel... 详细信息

ISBN: (纸本)9798350369311

关键词： Multiplexing Spectroscopy Laser mode locking Switches Laser stability Lasers and electrooptics Erbium-doped fiber lasers Laser excitation Sensors Pump lasers

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Multiagent Autonomous Source Search Using Submodularity and Branch-and-Bound

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无人系统（英文） 2024年第1期12卷 19-28页

作者： Xiaoling Xu Damián Marelli Wei Meng Qianqian Cai Minyue Fu School of Automation Guangdong University of TechnologyGuangdong Province Key Laboratory of Intelligent Decision and Cooperative Control Guangzhou 510006P.R.China School of Automation Guangdong University of TechnologyGuangdong Province Key Laboratory of Intelligent Decision and Cooperative Control Guangzhou 510006P.R.China French Argentine International Center for Information and Systems Sciences National Scientific and Technical Research Council Argentina School of Engineering University of Newcastle NSW 2308Australia

This paper is concerned with near-optimal source search problem using a multiagent system in cluttered indoor *** goal of the problem is to maximize the detection probability within the minimum search *** propose a two-stage strategy to achieve this *** the first stage,a greedy approach is used to define a set of grid cells with the aim of maximizing the detection *** the second stage,an iterative branch-and-bound procedure is used to design the search paths of all agents so that all grid cells are visited by one agent and the largest search path among all agents is *** results show that the proposed search algorithm has better performance in terms of exploration time compared to other existing methods.

关键词： Multiagent system source search submodularity branch-and-bound indoor exploration

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Biosignal-based Control of a Robotic Gait Training Lifter

Biosignal-based Control of a Robotic Gait Training Lifter

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Xiaoxi Zhang Hideki Kadone Tomohiro Konishi Yang Chen Modar Hassan Kenji Suzuki Artificial Intelligence Laboratory University of Tsukuba Tsukuba Japan Center for Innovative Medicine and Engineering University of Tsukuba Hospital Japan Institute of Systems and Information Engineering University of Tsukuba Tsukuba Japan

ISBN: (数字)9798350371499

ISBN: (纸本)9798350371505

In this paper, we present a robotic walker that aims to encourage the patient’s voluntary movement by enabling intention-based control of the mobile base. We proposed two variants of biosignal-based control methods for the robotic gait training lifter (GTL): one method to control the speed of the walker directly from Electromyography (EMG) signals of the muscles of the lower limb, and the other method to control the acceleration of the walker from EMG. We implemented these methods in a robotic walker and conducted experiments with one healthy male and one female participant to evaluate the feasibility of the proposed method. The results showed that the velocity of the human and walker can be synchronized with both controllers in the walking phase. The proposed method allows users to use together with robotic exoskeletons for rehabilitation sessions and has the potential to promote the active participation of the patient.

关键词： Legged locomotion Training Exoskeletons Muscles Electromyography Synchronization engineering in medicine and biology Robots

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CLIENT RECRUITMENT FOR FEDERATED LEARNING IN ICU LENGTH OF STAY PREDICTION

arXiv

引用

arXiv 2023年

作者： Scheltjens, Vincent Momo, Lyse Naomi Wamba Verbeke, Wouter De Moor, Bart KU Leuven STADIUS Center for Dynamical Systems Signal Processing and Data Analytics Belgium KU Leuven LIRIS Research Centre for Information Systems Engineering Belgium

Background: Machine and deep learning methods for medical and healthcare applications have shown significant progress and performance improvement in recent years. These methods require vast amounts of training data which are available in the medical sector, albeit decentralized. Medical institutions generate vast amounts of data for which sharing and centralizing remains a challenge as the result of data and privacy regulations. The federated learning technique is well-suited to tackle these challenges. However, federated learning comes with a new set of open problems related to communication overhead, efficient parameter aggregation, client selection strategies and more. Methods: In this work, we address the step prior to the initiation of a federated network for model training, client recruitment. By intelligently recruiting clients, communication overhead and overall cost of training can be reduced without sacrificing predictive performance. Client recruitment aims at pre-excluding potential clients from partaking in the federation based on a set of criteria indicative of their eventual contributions to the federation. In this work, we propose a client recruitment approach using only the output distribution and sample size at the client site. Results: We show how a subset of clients can be recruited without sacrificing model performance whilst, at the same time, significantly improving computation time. By applying the recruitment approach to the training of federated models for accurate patient Length of Stay prediction using data from 189 Intensive Care Units, we show how the models trained in federations made up from recruited clients significantly outperform federated models trained with the standard procedure in terms of predictive power and training time. © 2023, CC BY.

关键词： Intensive care units

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Study on Gait Stabilization Method Using Wearable Cyborg HAL Trunk-Unit for Parkinson's Disease and Parkinsonism with Freezing of Gait

Study on Gait Stabilization Method Using Wearable Cyborg HAL...

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IEEE International Conference on systems, Man and Cybernetics

作者： K. Ikeda A. Uehara H. Kawamoto Y. Sankai Department of Intelligent and Mechanical Interaction Systems University of Tsukuba Tsukuba Japan Faculty of Engineering Information and Systems Center of Cybernics Research University of Tsukuba Tsukuba Japan

Freezing of Gait (FOG) is one of the typical parkinsonian gait disturbances of progressive neurological disorders such as Parkinson's disease (PD) and progressive supranuclear palsy. Previous studies showed that the wearable cyborg HAL trunk-unit improved their gait disturbances through only an autonomous sway control that provided lateral swing with constant frequency. To promote the improvement by establishing interactive Bio-Feedback loop, it is necessary to realize synchronization between the wearer's intention and gait states for stabilizing gait, i.e. reducing variation of gait cycle. In this study, we developed a voluntary control method that responded to an intentional change in gait cycle and a method that switched 2 kinds of controls including the voluntary control method and the autonomous sway control method for stabilizing gait. The voluntary swing control method synchronized the HAL's force with wearer's gait in a stable gait state less prone to FOG. The autonomous sway control method provided lateral swing with constant frequency as feedback to the patients to achieve a gait state less prone to FOG. These controls were switched according to the gait stability calculated by wearer's gait cycle. Through the gait experiments with an abled-body participant, we confirmed that the HAL's lateral cyclic sway synchronized with the participant's gait and each control switched based on a gait stability. These results showed that the proposed methods had the feasibility of stabilizing gait.

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systems Modeling of Trust in AI-Enabled Medical Diagnosis

Systems Modeling of Trust in AI-Enabled Medical Diagnosis

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Annual IEEE systems Conference

作者： Negin Moghadasi Misagh Piran Rupa S. Valdez Negar Moghaddasi Davis C. Loose Thomas L. Polmateer James H. Lambert Dept. of Systems and Information Engineering University of Virginia Johnson & Johnson Medtech Charlottesville USA Dept. of Radiology Nuclear Medicine and Molecular Imaging Heart and Diabetes Center North-Rhine Westphalia Ruhr University of Bochum Bad Oeyhausen Germany Dept. of Systems and Information Engineering School of Data Science University of Virginia Charlottesville USA Dept. of Dentistry Western University of Health Sciences Pomona USA Dept. of Engineering Systems and Environment University of Virginia Charlottesville USA Dept. of Engineering Systems and Environment CCALS University of Virginia Charlottesville USA Dept. of Systems and Information Engineering University of Virginia Charlottesville USA

ISBN: (数字)9798350358803

ISBN: (纸本)9798350358810

The progression of artificial intelligence, particularly in healthcare domain, has brought significant progress to treatment, drug discovery, disease diagnosis and more. The main contribution of this paper is the development of a scenario-based preferences risk register framework for quantifying AI related risks in disease diagnosis. Two case studies, one involving physician and the other one with involving patients as the main stakeholders, are compared to evaluate the effectiveness of the framework and to evaluate how the initiatives ranking orders will evolve based on the most and least disruptive scenarios for each cases. The framework is applied to realistic case studies on cardiac sarcoidosis, identifying success criteria, initiatives, emergent conditions, and the most and least disruptive scenarios. The success criteria align with the National Institute of Standards and Technology AI Risk Management Framework (NIST AI RMF) seven trustworthy AI characteristics. Finally, the framework identifies the most and least disruptive scenarios and the most important initiatives for both cases. Results show that Non-Interpretable AI and Lack of Human-AI Communications, Privacy Attacks, and Human Errors in Design, Develop, Measurement and Implementation are the most disruptive scenarios in both cases, however, scenario Cyber Security Threats also counted as other most disruptive scenarios to the initiatives ranked by patients. This adaptable framework has the potential not only to transfer findings to global healthcare systems but also to extend its effectiveness to various other domains, such as transportation, finance, environment, and design.

关键词： Privacy Measurement uncertainty Transportation NIST systems modeling Registers Medical diagnosis

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IoT Cloud Computing Middleware for crowd monitoring and evacuation

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International Journal of Circuits, systems and Signal Processing 2021年 15卷 1790-1802页

作者： Gazis, Alexandros Katsiri, Eleftheria Democritus University of Thrace Department of Electrical and Computer Engineering Xanthi67100 Greece Institute for the Management of Information Systems Athena Research & Innovation Center in Information Communication & Knowledge Technologies Marousi15125 Greece

Map-Reduce is a programming model and an associated implementation for processing and generating large data sets. This model has a single point of failure: the master, who coordinates the work in a cluster. On the contrary, wireless sensor networks (WSNs) are distributed systems that scale and feature large numbers of small, computationally limited, low-power, unreliable nodes. In this article, we provide a top-down approach explaining the architecture, implementation and rationale of a distributed fault-tolerant IoT middleware. Specifically, this middleware consists of multiple mini-computing devices (Raspberry Pi) connected in a WSN which implement the Map-Reduce algorithm. First, we explain the tools used to develop this system. Second, we focus on the Map-Reduce algorithm implemented to overcome common network connectivity issues, as well as to enhance operation availability and reliability. Lastly, we provide benchmarks for our middleware as a crowd tracking application for a preserved building in Greece (i.e., M. Hatzidakis’ residence). The results of this study show that IoT middleware with low-power and low-cost components are viable solutions for medium-sized cloud computing distributed and parallel computing centres. Potential uses of this middleware apply for monitoring buildings and indoor structures, in addition to crowd tracking to prevent the spread of COVID-19. © 2021, North Atlantic University Union NAUN. All rights reserved.

关键词： Middleware

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Electricity Markets in a Time of Change: A Call to Arms for Business Research

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Schmalenbach Journal of Business Research 2022年第1期74卷 77-102页

作者： Bichler, Martin Buhl, Hans Ulrich Knörr, Johannes Maldonado, Felipe Schott, Paul Waldherr, Stefan Weibelzahl, Martin Department of Informatics Technical University of Munich Boltzmannstr. 3 Garching 85748 Germany FIM Research Center Project Group Business & Information Systems Engineering of the Fraunhofer FIT Alter Postweg 101 Augsburg 86159 Germany FIM Research Center University of Bayreuth Project Group Business & Information Systems Engineering of the Fraunhofer FIT Wittelsbacherring 10 Bayreuth 95444 Germany School of Business and Economics Vrije Universiteit Amsterdam De Boelelaan 1105 Amsterdam 1081 HV Netherlands

Europe’s clean energy transition is imperative to combat climate change and represents an economic opportunity to become independent of fossil fuels. As such, the energy transition has become one of the most important, but also one of the most challenging economic and societal projects today. Electricity systems of the past were characterized by price-inelastic demand and only a small number of large electricity generators. The transition towards intermittent renewable energy sources changes this very paradigm. Future electricity systems will consist of many thousands of electricity generators and consumers that actively participate in markets, offering flexibility to balance variable electricity supply in markets with a high spatial and temporal resolution. These structural changes have ample consequences for market operators, generators, industrial consumers as well as prosumers. While a large body of the literature is devoted to the energy transition in engineering and the natural sciences, it has received relatively little attention in the recent business research literature, even though many of the central challenges for a successful energy transition are at the core of business research. Therefore, we provide an up-to-date overview of key questions in electricity market design and discuss how changes in electricity markets lead to new research challenges in business research disciplines such as accounting, business & information systems engineering, finance, marketing, operations management, operations research, and risk management. © 2021, The Author(s).

关键词： Demand response Electricity market design Energy transition Renewable energy sources

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Projected spatio-temporal variations of soil moisture drought under CMIP6 climate change scenarios

Projected spatio-temporal variations of soil moisture drough...

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2023 American Society of Agricultural and Biological Engineers Annual International Meeting, ASABE 2023

作者： Jeon, Min-Gi Nam, Won-Ho Hong, Eun-Mi Department of Convergence of Information and Communication Engineering Hankyong National University Korea Republic of School of Social Safety and Systems Engineering Institute of Agricultural Environmental Science National Agricultural Water Research Center Hankyong National University Korea Republic of School of Natural Resources and Environmental Science Kangwon National University Korea Republic of

ISBN: (纸本)9781713885887

According to the United Nations Office for Disaster Risk Reduction (UNDRR), the frequency of natural disasters worldwide between 2000 and 2019 increased 1.7 times from the past 20 years (1980-1999) due to climate change. Climate change causes irregular changes in the size, frequency, and pattern of extreme precipitation, and directly affects changes in water resources such as hydrological circulation and outflow, and changes in agricultural environment, crop growth, and production. CMIP6 (Coupled Model Intercomparison Project 6), an international joint project on international standard climate experiments, developed SSP (Shared Socioeconomic Pathways), a new greenhouse gas reduction path considering future social and economic structural changes, depending on the level of greenhouse gas reduction and climate change adaptation measures for the IPCC (Intergovernmental Panel on Climate Change) 6th assessment report (AR6). In the case of rice paddies in South Korea, water supply systems are established from agricultural repair facilities such as agricultural reservoirs and pumping stations, while most upland crops rely on natural rainfall to supply water, making them relatively vulnerable to drought compared to rice paddies. In this study, attempts to simulate future soil moisture using SSP climate change scenarios and soil moisture models provided by CMIP6, and to identify future soil moisture variability and drought patterns by applying Runs theory based on calculated soil moisture. © 2023 ASABE Annual International Meeting. All Rights Reserved.

关键词： Climate change

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