期刊文献+
共找到161,774篇文章
< 1 2 250 >
每页显示 20 50 100
Modeling and Comprehensive Review of Signaling Storms in 3GPP-Based Mobile Broadband Networks:Causes,Solutions,and Countermeasures
1
作者 Muhammad Qasim Khan Fazal Malik +1 位作者 Fahad Alturise Noor Rahman 《Computer Modeling in Engineering & Sciences》 SCIE EI 2025年第1期123-153,共31页
Control signaling is mandatory for the operation and management of all types of communication networks,including the Third Generation Partnership Project(3GPP)mobile broadband networks.However,they consume important a... Control signaling is mandatory for the operation and management of all types of communication networks,including the Third Generation Partnership Project(3GPP)mobile broadband networks.However,they consume important and scarce network resources such as bandwidth and processing power.There have been several reports of these control signaling turning into signaling storms halting network operations and causing the respective Telecom companies big financial losses.This paper draws its motivation from such real network disaster incidents attributed to signaling storms.In this paper,we present a thorough survey of the causes,of the signaling storm problems in 3GPP-based mobile broadband networks and discuss in detail their possible solutions and countermeasures.We provide relevant analytical models to help quantify the effect of the potential causes and benefits of their corresponding solutions.Another important contribution of this paper is the comparison of the possible causes and solutions/countermeasures,concerning their effect on several important network aspects such as architecture,additional signaling,fidelity,etc.,in the form of a table.This paper presents an update and an extension of our earlier conference publication.To our knowledge,no similar survey study exists on the subject. 展开更多
关键词 Signaling storm problems control signaling load analytical modeling 3GPP networks smart devices diameter signaling mobile broadband data access data traffic mobility management signaling network architecture 5G mobile communication
下载PDF
基于MobileNetV3Small-ECA的水稻病害轻量级识别研究 被引量:6
2
作者 袁培森 欧阳柳江 +1 位作者 翟肇裕 田永超 《农业机械学报》 EI CAS CSCD 北大核心 2024年第1期253-262,共10页
为实现水稻病害的轻量化识别与检测,使用ECA注意力机制改进MobileNetV3Small模型,并使用共享参数迁移学习对水稻病害进行智能化轻量级识别和检测。在PlantVillage数据集上进行预训练,将预训练得到的共享参数迁移到对水稻病害识别模型上... 为实现水稻病害的轻量化识别与检测,使用ECA注意力机制改进MobileNetV3Small模型,并使用共享参数迁移学习对水稻病害进行智能化轻量级识别和检测。在PlantVillage数据集上进行预训练,将预训练得到的共享参数迁移到对水稻病害识别模型上微调优化。在开源水稻病害数据集上进行试验测试,试验结果表明,在非迁移学习下,识别准确率达到97.47%,在迁移学习下识别准确率达到99.92%,同时参数量减少26.69%。其次,通过Grad-CAM进行可视化,本文方法与其他注意力机制CBAM和SENET相比,ECA模块生成的结果与图像中病斑的位置和颜色更加一致,表明网络可以更好地聚焦水稻病害的特征,并且通过可视化和各水稻病害分析了误分类原因。本文方法实现了水稻病害识别模型的轻量化,使其能够在移动设备等资源受限的场景中部署,达到快速、高效、便携的目的。同时开发了基于Android的水稻病害识别系统,方便于在边缘端进行水稻病害识别分析。 展开更多
关键词 水稻病害识别 迁移学习 高效通道注意力机制 mobileNetV3Small 移动端部署
下载PDF
Node deployment strategy optimization for wireless sensor network with mobile base station 被引量:7
3
作者 龙军 桂卫华 《Journal of Central South University》 SCIE EI CAS 2012年第2期453-458,共6页
The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytica... The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytical method for avoiding energy hole was proposed. It is proved that if the densities of sensor nodes working at the same time are alternate between dormancy and work with non-uniform node distribution. The efficiency of network can increase by several times and the residual energy of network is nearly zero when the network lifetime ends. 展开更多
关键词 wireless sensor network mobile base station network optimization energy consumption balancing density ratio of sensor node network lifetime
下载PDF
Evaluation of a Mobile Station Electronic Health Record on Documentation Compliance and Nurses’ Attitudes 被引量:2
4
作者 Mei-Wen Wu Ting-Ting Lee +3 位作者 Tzu-Chuan Tsai Chin-Yi Huang Francis Fu-Sheng Wu Mary Etta Mills 《Open Journal of Nursing》 2015年第7期678-688,共11页
Electronic Health Record (EHR) Systems have been adopted by healthcare organizations for documentation of patient care. Often these information systems are embedded in mobile nurse stations. As part of assessing the i... Electronic Health Record (EHR) Systems have been adopted by healthcare organizations for documentation of patient care. Often these information systems are embedded in mobile nurse stations. As part of assessing the impact of this technology it is important to determine the effect it has on charting compliance and user acceptance. Data were collected at a medical center in Taiwan in two stages. The first stage involved use of a 28-item medical review tool to measure charting compliance in 99 charts before and after implementation of the EHR system. In stage two, a survey was conducted with 709 nurse users to determine their level of mobile EHR acceptance 3 months after this documentation technology was initiated. Results demonstrated that EHR significantly improved documentation compliance in standardized data entry format (name, date, time), abbreviation, content correction/revision, patient care needs, and care goals. Analysis of data from the five categories of a user acceptance survey revealed the following results (based on a 4-point Likert scale): patient care (2.92), nursing efficiency (2.78), education and training (2.98), usability (2.61), and usage benefits (2.87). The study concluded that use of mobile nurse stations with EHR can improve documentation compliance and that although frequent system downtime needs improvement, nurses generally have positive attitudes toward this technology application. 展开更多
关键词 DOCUMENTATION COMPLIANCE Information System mobile NURSING station NURSE ATTITUDES Technology
下载PDF
A mobile polar atmospheric parameter measurement system:Ⅱ. First atmospheric turbulence observation at Antarctic Taishan Station 被引量:2
5
作者 TIAN Qiguo JIANG Peng +6 位作者 WU Xiaoqing JIN Xinmiao LU Shan JI Tuo CHAI Bo ZHANG Shaohua ZHOU Hongyan 《Advances in Polar Science》 2015年第2期140-146,共7页
This is the second paper of a series devoted to atmospheric optical turbulence Cn^2 observation using a mobile polar atmospheric parameter measurement system. We present the initial results of Cn^2 measurement at Anta... This is the second paper of a series devoted to atmospheric optical turbulence Cn^2 observation using a mobile polar atmospheric parameter measurement system. We present the initial results of Cn^2 measurement at Antarctic Taishan Station using micro-thermal sensors and a three-dimensional sonic anemometer at height -2.0 m above the snow surface. The site testing experiments were carried out during the 30th Chinese National Antarctic Research Expedition (CH1NARE). We collected about 1 000 h of data between 30 December 2013 and 10 February 2014. The C,: curve exhibits clear daily structures, with two peaks around midnight and midday and two troughs around 7:30 and 17:00 local time (UTC+5). The mean C,2 is 2.7×10^-15 m^-2/3 and the 25th and 75th percentiles of the C,2 cumulative distribution are 9.6×10^-16 m^-2/3 and 6.2×10^-15 m^-2/3, respectively. Meteorological parameters such as temperature, relative humidity, wind speed, and air pressure are also presented. 展开更多
关键词 micro-thermal sensors three-dimensional sonic anemometer turbulence site testing Antarctic Plateau Kunlun station Taishan station
下载PDF
Location correction technique based on mobile communication base station for earthquake population heat map
6
作者 Xiaoli Liu Xue Li +2 位作者 Xiaolin Chen Zhumei Liu Shengle Li 《Geodesy and Geodynamics》 2018年第5期388-397,共10页
China has mobile phone penetration rate of over 96.2%.Mobile phone has become the largest Internet terminal for Chinese Internet users.Population geographic distribution in earthquake zones can be got based on mobile ... China has mobile phone penetration rate of over 96.2%.Mobile phone has become the largest Internet terminal for Chinese Internet users.Population geographic distribution in earthquake zones can be got based on mobile phone positioning and map matching.For reducing earthquake black-box stage,we propose a real-time collection,correction and schedule algorithm of population position data by four stream processing environments(Redis,Hbase,Kafka,and Spark Streaming)in this paper.For labeling precisely population geographic distribution on the network map,matching of population geographic coordinates and map coordinates are optimized by sample comparison based on location data of mobile communication base stations and prefecture level cities.The test result shows the proposed system is high efficient and can rapidly respond to any emerging parallel tasks during the earthquake.A high-precision heat map of affected population can be produced and published on-line within 2 min after the devastating earthquake happened. 展开更多
关键词 Earthquake emergency Location-based service mobile communication base station Big data technology
下载PDF
ZTE Launched First SDR Base Station at GSMA Mobile World Congress 2008
7
《ZTE Communications》 2008年第1期67-67,共1页
ZTE Corporation ("ZTE"), a leading global provider of telecommunications equipment and network solutions,
关键词 ZTE Launched First SDR Base station at GSMA mobile World Congress 2008 Base GSMA WiMAX SDR World
下载PDF
Effects of Exposure to GSM Mobile Phone Base Station Signals on Salivary Cortisol,Alpha-Amylase,and Immunoglobulin A
8
作者 CHRISTOPH AUGNER GERHARD W.HACKER +4 位作者 GERD OBERFELD MATTHIAS FLORIAN WOLFGANG HITZL JORG HUTTER GERNOT PAUSER 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2010年第3期199-207,共9页
Objective The present study aimed to test whether exposure to radiofrequency electromagnetic fields (RF-EMF) emitted by mobile phone base stations may have effects on salivary alpha-amylase, immunoglobulin A (IgA)... Objective The present study aimed to test whether exposure to radiofrequency electromagnetic fields (RF-EMF) emitted by mobile phone base stations may have effects on salivary alpha-amylase, immunoglobulin A (IgA), and cortisol levels. Methods Fifty seven participants were randomly allocated to one of three different experimental scenarios (22 participants to scenario 1, 26 to scenario 2, and 9 to scenario 3). Each participant went through five 50-minute exposure sessions. The main RF-EMF source was a GSM-900-MHz antenna located at the outer wall of the building. In scenarios 1 and 2, the first, third, and fifth sessions were "low" (median power flux density 5.2 μW/m^2) exposure. The second session was "high" (2126.8 μW/m^2), and the fourth session was "medium" (153.6 μW/m^2) in scenario 1, and vice versa in scenario 2. Scenario 3 had four "low" exposure conditions, followed by a "high" exposure condition. Biomedical parameters were collected by saliva samples three times a session. Exposure levels were created by shielding curtains. Results In scenario 3 from session 4 to session 5 (from "low" to "high" exposure), an increase of cortisol was detected, while in scenarios 1 and 2, a higher concentration of alpha-amylase related to the baseline was identified as compared to that in scenario 3. IgA concentration was not significantly related to the exposure. Conclusions RF-EMF in considerably lower field densities than ICNIRP-gnidelines may influence certain psychobiological stress markers. 展开更多
关键词 GSM base stations mobile phone Salivary IgA Alpha amylase CORTISOL Radiofrequency electromagnetic fields (RF-EMF)
下载PDF
Analysis of Lightning Disaster of Eight Mobile Base Stations in a County Suffering Thunderstorm on June 23,2015 and Countermeasures
9
作者 Pei Jun Zhou Liping Ning Xia 《Meteorological and Environmental Research》 CAS 2016年第4期29-30,共2页
During the process of thunderstorm in a county on June 23,2015,eight mobile base stations in the region were damaged.The reasons for the damage caused by the thunderstorm were discussed through on-the-spot investigati... During the process of thunderstorm in a county on June 23,2015,eight mobile base stations in the region were damaged.The reasons for the damage caused by the thunderstorm were discussed through on-the-spot investigation,and some countermeasures were proposed. 展开更多
关键词 THUNDERSTORM LIGHTNING disaster mobile base stationS COUNTERMEASURES China
下载PDF
Analysis of Dispersed Lightning Stroke around a Mobile Communication Base Station
10
作者 Song Min Fu Lili 《Meteorological and Environmental Research》 CAS 2016年第2期33-35,共3页
A case of villagers suffering lightning stroke around the tower of a mobile communication base station was investigated to analyze its reasons,and the countermeasures against lightning stroke were proposed. The result... A case of villagers suffering lightning stroke around the tower of a mobile communication base station was investigated to analyze its reasons,and the countermeasures against lightning stroke were proposed. The results show that the lightning stroke event is related to dispersed lightning stroke. To avoid the damage caused by lightning stroke,it is needed to equip a house in the dispersed lightning stroke zone with lightning protection system and spread lightning protection knowledge among the villagers. 展开更多
关键词 mobile communication base station Lightning induction Dispersed lightning stroke China
下载PDF
Application of Mobile Intelligent Inspection System in Substation Equipment Management
11
作者 Danli Long 《Energy and Power Engineering》 2017年第4期408-413,共6页
Intelligent inspection is more and more widely applied in all walks of life. This paper introduces the application of the intelligent inspection system in substation equipment management based on mobile phone terminal... Intelligent inspection is more and more widely applied in all walks of life. This paper introduces the application of the intelligent inspection system in substation equipment management based on mobile phone terminal. It can make the power supply enterprise have more effective means to ensure the safe operation of equipment, improve equipment management level, and improve the economic benefits of power supply. 展开更多
关键词 mobile INTELLIGENT INSPECTION System SUBstation Operating DEVICE MANAGEMENT
下载PDF
A Sector Antenna for Mobile Base Station Using MSA Array with Curved Woodpile EBG
12
作者 Rangsan Wongsan Piyaporn Krachodnok Paowphattra Kamphikul 《Open Journal of Antennas and Propagation》 2014年第1期1-8,共8页
This paper presents a sector antenna for base station of mobile phone using microstrip antenna (MSA) array with curved woodpile Electromagnetic Band Gap (EBG). The advantages of this pro- posed antenna are easy fabric... This paper presents a sector antenna for base station of mobile phone using microstrip antenna (MSA) array with curved woodpile Electromagnetic Band Gap (EBG). The advantages of this pro- posed antenna are easy fabrication and installation, high gain, and light weight. Moreover, it pro- vides a fan-shaped radiation pattern , a main beam having a narrow beam width in the vertical di- rection and a wider beamwidth in the horizontal direction, which are appropriate for mobile phone base station. The half-power beamwidths in the H-plane and E-plane are 37.4 and 8.7 de- grees, respectively. The paper also presents the design procedures of a 1 × 8 array antenna using MSAs associated with U-shaped reflector for decreasing their back and side lobes. A Computer Si- mulation Technology (CST) software has been used to compute the reflection coefficient (S11), radiation patterns, and gain of this antenna. The bandwidth, at S11 (?10 dB), is enough, which can be well utilized for 3G base station, with a gain 20.84 dB. 展开更多
关键词 MICROSTRIP ANTENNA Electromagnetic Band Gap Base station
下载PDF
Design of a Magneto-Electric Dipole Element for Mobile Communication Base Station Antennas
13
作者 Hang Wong Kwai Man Luk 《ZTE Communications》 2011年第2期20-26,共7页
The magneto-electric dipole antenna is a kind of complementary antenna composed of a planar electric dipole and a shorted patch antenna. It has excellent electrical characteristics including wide impedance bandwidth, ... The magneto-electric dipole antenna is a kind of complementary antenna composed of a planar electric dipole and a shorted patch antenna. It has excellent electrical characteristics including wide impedance bandwidth, low cross-polarization, low back lobe radiation, nearly identical E-plane and H-plane patterns, stable radiation pattern, and steady antenna gain over the operating frequency range. In this paper, the basic characteristics of a linearly polarized magneto-electric dipole antenna are reviewed, and a dual-polarized antenna element based on the magneto-electric dipole is presented. The design of a conical beam wideband antenna with horizontal polarization is also described. These antennas have practical applications in modern 2G, 3G, LTE, WiFi, and WiMax wireless communication systems. 展开更多
关键词 base station antenna magneto electric dipole wideband antenna dual polarization
下载PDF
Air-Ground Collaborative Mobile Edge Computing:Architecture,Challenges,and Opportunities 被引量:1
14
作者 Qin Zhen He Shoushuai +5 位作者 Wang Hai Qu Yuben Dai Haipeng Xiong Fei Wei Zhenhua Li Hailong 《China Communications》 SCIE CSCD 2024年第5期1-16,共16页
By pushing computation,cache,and network control to the edge,mobile edge computing(MEC)is expected to play a leading role in fifth generation(5G)and future sixth generation(6G).Nevertheless,facing ubiquitous fast-grow... By pushing computation,cache,and network control to the edge,mobile edge computing(MEC)is expected to play a leading role in fifth generation(5G)and future sixth generation(6G).Nevertheless,facing ubiquitous fast-growing computational demands,it is impossible for a single MEC paradigm to effectively support high-quality intelligent services at end user equipments(UEs).To address this issue,we propose an air-ground collaborative MEC(AGCMEC)architecture in this article.The proposed AGCMEC integrates all potentially available MEC servers within air and ground in the envisioned 6G,by a variety of collaborative ways to provide computation services at their best for UEs.Firstly,we introduce the AGC-MEC architecture and elaborate three typical use cases.Then,we discuss four main challenges in the AGC-MEC as well as their potential solutions.Next,we conduct a case study of collaborative service placement for AGC-MEC to validate the effectiveness of the proposed collaborative service placement strategy.Finally,we highlight several potential research directions of the AGC-MEC. 展开更多
关键词 air-ground architecture COLLABORATIVE mobile edge computing
下载PDF
Intra and Inter-Observer Reliability of Mobile Tablet PACS Viewer System vs. Standard PACS Viewing Station-Diagnosis of Acute Central Nervous System Events
15
作者 Aashim Bhatia Sandip Patel +3 位作者 Gustavo Pantol Yen-Ying Wu Michael Plitnikas Christopher Hancock 《Open Journal of Radiology》 2013年第2期91-98,共8页
Background and Purpose: The display resolution of the Apple iPad? is 1024 × 768 pixels, which is greater than that required for generating the typical CT or MRI images. The purpose of this study is to determine i... Background and Purpose: The display resolution of the Apple iPad? is 1024 × 768 pixels, which is greater than that required for generating the typical CT or MRI images. The purpose of this study is to determine if specific CT and MR sequences can be interpreted accurately on mobile device/PACS software platforms when compared to a traditional stationary high resolution monitor/PACS radiological workstation. If so, this allows radiologists to provide comparable interpretation as if they were onsite at an imaging center or hospital. Materials and Methods: This study is an investigator initiated, single site, retrospective, nonrandomized, IRB approved study. Five radiologists were included in this study. Each independently interpreted specific CT and MR sequences on traditional high-resolution LCD monitors via eFilm? software as well as an iPad? mobile device using Osirix? software program. Repeat interpretations were performed, with 4 weeks minimum interval between interpretations of each patient. This investigation included: 50 patients with CTA perfusion imaging, 50 patients with MRI of the brain, and 50 patients with MRI of the spine, which were image study orders generated through emergency room requests. Subsequently, interpretive results of each radiologist for each patient were statistically compared to evaluate for intra-observer and inter-observer reliability. Results: The parameters set within the CTA perfusion brain studies demonstrated excellent intra-observer variability. All of the parameters within the MRI brain studies demonstrated excellent intra-observer variability with a Cohen’s kappa value > 0.75. The Cohen’s kappa values for the board certified neuroradiologist demonstrated excellent variability for all parameters;the resident radiologists had good variability, with a majority of kappa values near 0.75. Conclusions: The data and statistical analysis demonstrated that portable mobile devices such as the Apple iPad? can display adequate resolution of CT and MRI sequences to accurately diagnose acute central nervous system injuries and other non-acute pathology. 展开更多
关键词 TELERADIOLOGY Telemedicine Cloud Network PACS mobile Device Emergency ACUTE Stroke
下载PDF
(EERSM): Energy-Efficient Multi-Hop Routing Technique in Wireless Sensor Networks Based on Combination between Stationary and Mobile Nodes
16
作者 Fawaz Alassery 《Journal of Computer and Communications》 2019年第4期31-52,共22页
In Wireless Sensor Network (WSNs), sensor nodes collect data and send them to a Base Station (BS) for further processing. One of the most issues in WSNs that researchers have proposed a hundred of technique to solve i... In Wireless Sensor Network (WSNs), sensor nodes collect data and send them to a Base Station (BS) for further processing. One of the most issues in WSNs that researchers have proposed a hundred of technique to solve its impact is the energy constraint since sensor nodes have small battery, small memory and less data processing with low computational capabilities. However, many researches efforts have focused on how to prolong the battery lifetime of sensor nodes by proposing different routing, MAC, localization, data aggregation, topology construction techniques. In this paper, we will focus on routing techniques which aim to prolonging the network lifetime. Hence, we propose an Energy-Efficient Routing technique in WSNs based on Stationary and Mobile nodes (EERSM). Sensing filed is divided into intersected circles which contain Mobile Nodes (MN). The proposed data aggregation technique via the circular topology will eliminate the redundant data to be sent to the Base Station (BS). MN in each circle will rout packets for their source nodes, and move to the intersected area where another MN is waiting (sleep mode) to receive the transmitted packet, and then the packet will be delivered to the next intersected area until the packet is arrived to the BS. Our proposed EERSM technique is simulated using MATLAB and compared with conventional multi-hop techniques under different network models and scenarios. In the simulation, we will show how the proposed EERSM technique overcomes many routing protocols in terms of the number of hops counted when sending packets from a source node to the destination (i.e. BS), the average residual energy, number of sent packets to the BS, and the number of a live sensor nodes verse the simulation rounds. 展开更多
关键词 Energy Efficiency in WSNS Data AGGREGATION of WSNS mobile NODES in WSNS MULTI-HOP Routing in WSNS Power Efficient Techniques
下载PDF
Leveraging User-Generated Comments and Fused BiLSTM Models to Detect and Predict Issues with Mobile Apps 被引量:1
17
作者 Wael M.S.Yafooz Abdullah Alsaeedi 《Computers, Materials & Continua》 SCIE EI 2024年第4期735-759,共25页
In the last decade, technical advancements and faster Internet speeds have also led to an increasing number ofmobile devices and users. Thus, all contributors to society, whether young or old members, can use these mo... In the last decade, technical advancements and faster Internet speeds have also led to an increasing number ofmobile devices and users. Thus, all contributors to society, whether young or old members, can use these mobileapps. The use of these apps eases our daily lives, and all customers who need any type of service can accessit easily, comfortably, and efficiently through mobile apps. Particularly, Saudi Arabia greatly depends on digitalservices to assist people and visitors. Such mobile devices are used in organizing daily work schedules and services,particularly during two large occasions, Umrah and Hajj. However, pilgrims encounter mobile app issues such asslowness, conflict, unreliability, or user-unfriendliness. Pilgrims comment on these issues on mobile app platformsthrough reviews of their experiences with these digital services. Scholars have made several attempts to solve suchmobile issues by reporting bugs or non-functional requirements by utilizing user comments.However, solving suchissues is a great challenge, and the issues still exist. Therefore, this study aims to propose a hybrid deep learningmodel to classify and predict mobile app software issues encountered by millions of pilgrims during the Hajj andUmrah periods from the user perspective. Firstly, a dataset was constructed using user-generated comments fromrelevant mobile apps using natural language processing methods, including information extraction, the annotationprocess, and pre-processing steps, considering a multi-class classification problem. Then, several experimentswere conducted using common machine learning classifiers, Artificial Neural Networks (ANN), Long Short-TermMemory (LSTM), and Convolutional Neural Network Long Short-Term Memory (CNN-LSTM) architectures, toexamine the performance of the proposed model. Results show 96% in F1-score and accuracy, and the proposedmodel outperformed the mentioned models. 展开更多
关键词 mobile apps issues play store user comments deep learning LSTM bidirectional LSTM
下载PDF
Safety Measurements of Electromagnetic Fields Radiated from Mobile Base Stations in the Western Region of Saudi Arabia
18
作者 Mouaaz Nahas Mohammed T. Simsim 《Wireless Engineering and Technology》 2011年第4期221-229,共9页
Over the last decade, detrimental effects of human exposure to electromagnetic radiations have received widespread attention. Communications and Information Technology Commission (CITC) in Saudi Arabia has set guideli... Over the last decade, detrimental effects of human exposure to electromagnetic radiations have received widespread attention. Communications and Information Technology Commission (CITC) in Saudi Arabia has set guidelines and launched a national project—in collaboration with academic and research institutions—to perform measurements of the “electromagnetic fields” (EMFs) radiated from base stations of the mobile phone network. In keeping with its mission to address problems of the local community, Electrical Engineering (EE) department at Umm Al-Qura University (UQU) has been commissioned to conduct this project in the western region of Saudi Arabia. The project is concerned with measuring the strength of EMFs around base stations to locate the Maximum Peak Point (MPP). The aim of measurements is to ensure the site compliance with the CITC guidelines for human exposure to Radiofrequency (RF). This paper discusses possible health consequences caused by human exposure to RF radiations. Furthermore, it sum- marizes the results from 20 selective base stations located in Makkah, Madinah, Jeddah, Taif and Yanbu. The results show that EMF levels at all surveyed sites are far below the National Guidelines for public exposure to RF and that the MPPs are found within the distance range suggested in the CITC guidelines. The paper concludes by providing some useful comments and recommendations for RF sites surveyors. 展开更多
关键词 Electromagnetic FIELDS Base station Maximum PEAK Point RADIOFREQUENCY Power Density Public LIMIT OCCUPATIONAL LIMIT National Guidelines
下载PDF
Adaptive Trajectory Tracking Control for Nonholonomic Wheeled Mobile Robots:A Barrier Function Sliding Mode Approach 被引量:1
19
作者 Yunjun Zheng Jinchuan Zheng +3 位作者 Ke Shao Han Zhao Hao Xie Hai Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第4期1007-1021,共15页
The trajectory tracking control performance of nonholonomic wheeled mobile robots(NWMRs)is subject to nonholonomic constraints,system uncertainties,and external disturbances.This paper proposes a barrier function-base... The trajectory tracking control performance of nonholonomic wheeled mobile robots(NWMRs)is subject to nonholonomic constraints,system uncertainties,and external disturbances.This paper proposes a barrier function-based adaptive sliding mode control(BFASMC)method to provide high-precision,fast-response performance and robustness for NWMRs.Compared with the conventional adaptive sliding mode control,the proposed control strategy can guarantee that the sliding mode variables converge to a predefined neighborhood of origin with a predefined reaching time independent of the prior knowledge of the uncertainties and disturbances bounds.Another advantage of the proposed algorithm is that the control gains can be adaptively adjusted to follow the disturbances amplitudes thanks to the barrier function.The benefit is that the overestimation of control gain can be eliminated,resulting in chattering reduction.Moreover,a modified barrier function-like control gain is employed to prevent the input saturation problem due to the physical limit of the actuator.The stability analysis and comparative experiments demonstrate that the proposed BFASMC can ensure the prespecified convergence performance of the NWMR system output variables and strong robustness against uncertainties/disturbances. 展开更多
关键词 Adaptive sliding mode barrier function nonholonomic wheeled mobile robot(NWMR) trajectory tracking control
下载PDF
A finite-time fuzzy adaptive output-feedback fault-tolerant control for underactuated wheeled mobile robots systems 被引量:1
20
作者 Pingfan Liu Shaocheng Tong 《Journal of Automation and Intelligence》 2024年第2期111-118,共8页
This paper investigates the adaptive fuzzy finite-time output-feedback fault-tolerant control (FTC) problemfor a class of nonlinear underactuated wheeled mobile robots (UWMRs) system with intermittent actuatorfaults. ... This paper investigates the adaptive fuzzy finite-time output-feedback fault-tolerant control (FTC) problemfor a class of nonlinear underactuated wheeled mobile robots (UWMRs) system with intermittent actuatorfaults. The UWMR system includes unknown nonlinear dynamics and immeasurable states. Fuzzy logic systems(FLSs) are utilized to work out immeasurable functions. Furthermore, with the support of the backsteppingcontrol technique and adaptive fuzzy state observer, a fuzzy adaptive finite-time output-feedback FTC scheme isdeveloped under the intermittent actuator faults. It is testifying the scheme can ensure the controlled nonlinearUWMRs is stable and the estimation errors are convergent. Finally, the comparison results and simulationvalidate the effectiveness of the proposed fuzzy adaptive finite-time FTC approach. 展开更多
关键词 Underactuated wheeled mobile robots system FINITE-TIME Fuzzy adaptive fault-tolerant control OUTPUT-FEEDBACK Intermittent actuator faults
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部