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Atmospheric neutron single event effects for multiple convolutional neural networks based on 28-nm and 16-nm SoC
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作者 Xu Zhao Xuecheng Du +3 位作者 Chao Ma Zhiliang Hu Weitao Yang Bo Zheng 《Chinese Physics B》 2025年第1期477-484,共8页
The single event effects(SEEs)evaluations caused by atmospheric neutrons were conducted on three different convolutional neural network(CNN)models(Yolov3,MNIST,and ResNet50)in the atmospheric neutron irradiation spect... The single event effects(SEEs)evaluations caused by atmospheric neutrons were conducted on three different convolutional neural network(CNN)models(Yolov3,MNIST,and ResNet50)in the atmospheric neutron irradiation spectrometer(ANIS)at the China Spallation Neutron Source(CSNS).The Yolov3 and MNIST models were implemented on the XILINX28-nm system-on-chip(So C).Meanwhile,the Yolov3 and ResNet50 models were deployed on the XILINX 16-nm Fin FET Ultra Scale+MPSoC.The atmospheric neutron SEEs on the tested CNN systems were comprehensively evaluated from six aspects,including chip type,network architecture,deployment methods,inference time,datasets,and the position of the anchor boxes.The various types of SEE soft errors,SEE cross-sections,and their distribution were analyzed to explore the radiation sensitivities and rules of 28-nm and 16-nm SoC.The current research can provide the technology support of radiation-resistant design of CNN system for developing and applying high-reliability,long-lifespan domestic artificial intelligence chips. 展开更多
关键词 single event effects atmospheric neutron system on chip convolutional neural network
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Drivers for Inter-city Innovation Networks Across Chinese Cities:Modelling Physical Versus Intangible Effects
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作者 GAO Yujie SCHERNGELL Thomas NEULÄNDTNER Martina 《Chinese Geographical Science》 SCIE CSCD 2024年第4期706-721,共16页
Cross-region innovation is widely recognized as an important source of the long-term regional innovation capacity.In the recent past,a growing number of studies has investigated the network structure and mechanisms of... Cross-region innovation is widely recognized as an important source of the long-term regional innovation capacity.In the recent past,a growing number of studies has investigated the network structure and mechanisms of cross-region innovation collaboration in various contexts.However,existing research mainly focuses on physical effects,such as geographical distance and high-speed railway connections.These studies ignore the intangible drivers in a changing environment,the more digitalized economy and the increasingly solidified innovation network structure.Thus,the focus of this study is on estimating determinants of innovation networks,especially on intangible drivers,which have been largely neglected so far.Using city-level data of Chinese patents(excluding Hong Kong,Macao,and Taiwan Province of China),we trace innovation networks across Chinese cities over a long period of time.By integrating a measure on Information and Communications Technology(ICT)development gap and network structural effects into the general proximity framework,this paper explores the changing mechanisms of Chinese innovation networks from a new perspective.The results show that the structure of cross-region innovation networks has changed in China.As mechanisms behind this development,the results confirm the increasingly important role of intangible drivers in Chinese inter-city innovation collaboration when controlling for effects of physical proximity,such as geographical distance.Since digitalization and coordinated development are the mainstream trends in China and other developing countries,these countries'inter-city innovation collaboration patterns will witness dramatic changes under the influence of intangible drivers. 展开更多
关键词 inter-city innovation network co-patents information and communications technology development network structural effect spatial interaction model China
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Studying the co-evolution of information diffusion,vaccination behavior and disease transmission in multilayer networks with local and global effects
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作者 霍良安 武兵杰 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期677-689,共13页
Today,with the rapid development of the internet,a large amount of information often accompanies the rapid transmission of disease outbreaks,and increasing numbers of scholars are studying the relationship between inf... Today,with the rapid development of the internet,a large amount of information often accompanies the rapid transmission of disease outbreaks,and increasing numbers of scholars are studying the relationship between information and the disease transmission process using complex networks.In fact,the disease transmission process is very complex.Besides this information,there will often be individual behavioral measures and other factors to consider.Most of the previous research has aimed to establish a two-layer network model to consider the impact of information on the transmission process of disease,rarely divided into information and behavior,respectively.To carry out a more in-depth analysis of the disease transmission process and the intrinsic influencing mechanism,this paper divides information and behavior into two layers and proposes the establishment of a complex network to study the dynamic co-evolution of information diffusion,vaccination behavior,and disease transmission.This is achieved by considering four influential relationships between adjacent layers in multilayer networks.In the information layer,the diffusion process of negative information is described,and the feedback effects of local and global vaccination are considered.In the behavioral layer,an individual's vaccination behavior is described,and the probability of an individual receiving a vaccination is influenced by two factors:the influence of negative information,and the influence of local and global disease severity.In the disease layer,individual susceptibility is considered to be influenced by vaccination behavior.The state transition equations are derived using the micro Markov chain approach(MMCA),and disease prevalence thresholds are obtained.It is demonstrated through simulation experiments that the negative information diffusion is less influenced by local vaccination behavior,and is mainly influenced by global vaccination behavior;vaccination behavior is mainly influenced by local disease conditions,and is less influenced by global disease conditions;the disease transmission threshold increases with the increasing vaccination rate;and the scale of disease transmission increases with the increasing negative information diffusion rate and decreases with the increasing vaccination rate.Finally,it is found that when individual vaccination behavior considers both the influence of negative information and disease,it can increase the disease transmission threshold and reduce the scale of disease transmission.Therefore,we should resist the diffusion of negative information,increase vaccination proportions,and take appropriate protective measures in time. 展开更多
关键词 information diffusion vaccination behavior disease transmission multilayer networks local and global effect
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Assessing target optical camouflage effects using brain functional networks:A feasibility study
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作者 Zhou Yu Li Xue +4 位作者 Weidong Xu Jun Liu Qi Jia Jianghua Hu Jidong Wu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第4期69-77,共9页
Brain functional networks model the brain's ability to exchange information across different regions,aiding in the understanding of the cognitive process of human visual attention during target searching,thereby c... Brain functional networks model the brain's ability to exchange information across different regions,aiding in the understanding of the cognitive process of human visual attention during target searching,thereby contributing to the advancement of camouflage evaluation.In this study,images with various camouflage effects were presented to observers to generate electroencephalography(EEG)signals,which were then used to construct a brain functional network.The topological parameters of the network were subsequently extracted and input into a machine learning model for training.The results indicate that most of the classifiers achieved accuracy rates exceeding 70%.Specifically,the Logistic algorithm achieved an accuracy of 81.67%.Therefore,it is possible to predict target camouflage effectiveness with high accuracy without the need to calculate discovery probability.The proposed method fully considers the aspects of human visual and cognitive processes,overcomes the subjectivity of human interpretation,and achieves stable and reliable accuracy. 展开更多
关键词 Camouflage effect evaluation Electroencephalography(EEG) Brain functional networks Machine learning
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Single event effects evaluation on convolution neural network in Xilinx 28 nm system on chip
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作者 赵旭 杜雪成 +4 位作者 熊旭 马超 杨卫涛 郑波 周超 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期638-644,共7页
Convolutional neural networks(CNNs) exhibit excellent performance in the areas of image recognition and object detection, which can enhance the intelligence level of spacecraft. However, in aerospace, energetic partic... Convolutional neural networks(CNNs) exhibit excellent performance in the areas of image recognition and object detection, which can enhance the intelligence level of spacecraft. However, in aerospace, energetic particles, such as heavy ions, protons, and alpha particles, can induce single event effects(SEEs) that lead CNNs to malfunction and can significantly impact the reliability of a CNN system. In this paper, the MNIST CNN system was constructed based on a 28 nm systemon-chip(SoC), and then an alpha particle irradiation experiment and fault injection were applied to evaluate the SEE of the CNN system. Various types of soft errors in the CNN system have been detected, and the SEE cross sections have been calculated. Furthermore, the mechanisms behind some soft errors have been explained. This research will provide technical support for the design of radiation-resistant artificial intelligence chips. 展开更多
关键词 single event effects convolutional neural networks alpha particle system on chip fault injection
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Evaluating the Effectiveness of Graph Convolutional Network for Detection of Healthcare Polypharmacy Side Effects
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作者 Omer Nabeel Dara Tareq Abed Mohammed Abdullahi Abdu Ibrahim 《Intelligent Automation & Soft Computing》 2024年第6期1007-1033,共27页
Healthcare polypharmacy is routinely used to treat numerous conditions;however,it often leads to unanticipated bad consequences owing to complicated medication interactions.This paper provides a graph convolutional ne... Healthcare polypharmacy is routinely used to treat numerous conditions;however,it often leads to unanticipated bad consequences owing to complicated medication interactions.This paper provides a graph convolutional network(GCN)-based model for identifying adverse effects in polypharmacy by integrating pharmaceutical data from electronic health records(EHR).The GCN framework analyzes the complicated links between drugs to forecast the possibility of harmful drug interactions.Experimental assessments reveal that the proposed GCN model surpasses existing machine learning approaches,reaching an accuracy(ACC)of 91%,an area under the receiver operating characteristic curve(AUC)of 0.88,and an F1-score of 0.83.Furthermore,the overall accuracy of the model achieved 98.47%.These findings imply that the GCN model is helpful for monitoring individuals receiving polypharmacy.Future research should concentrate on improving the model and extending datasets for therapeutic applications. 展开更多
关键词 POLYPHARMACY side effects drug-drug interactions graph convolutional networks deep learning medication network
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Modelling infrastructure interdependencies and cascading effects using temporal networks
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作者 Gian Paolo Cimellaro Alessandro Cardoni Andrei Reinhorn 《Resilient Cities and Structures》 2024年第3期28-42,共15页
Lifelines are critical infrastructure systems characterized by a high level of interdependency that can lead to cascading failures after any disaster.Many approaches can be used to analyze infrastructural interdepende... Lifelines are critical infrastructure systems characterized by a high level of interdependency that can lead to cascading failures after any disaster.Many approaches can be used to analyze infrastructural interdependencies,but they are usually not able to describe the sequence of events during emergencies.Therefore,interdependencies need to be modeled also taking into account the time effects.The methodology proposed in this paper is based on a modified version of the Input-output Inoperability Model and returns the probabilities of failure for each node of the system.Lifelines are modeled using graph theory,while perturbations,representing a natural or man-made disaster,are applied to the elements of the network following predetermined rules.The cascading effects among interdependent networks have been simulated using a spatial multilayer approach,while the use of an adjacency tensor allows to consider the temporal dimension and its effects.The method has been tested on a case study based on the 2011 Fukushima Dai-ichi nuclear disaster.Different configurations of the system have been analyzed and their probability of occurrence evaluated.Two models of the nuclear power plant have been developed to evaluate how different spatial scales and levels of detail affect the results. 展开更多
关键词 Interdependent infrastructure Nuclear power plant Cascading effects Temporal networks Input-output methods
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Source localization in signed networks with effective distance
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作者 马志伟 孙蕾 +2 位作者 丁智国 黄宜真 胡兆龙 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期577-585,共9页
While progress has been made in information source localization,it has overlooked the prevalent friend and adversarial relationships in social networks.This paper addresses this gap by focusing on source localization ... While progress has been made in information source localization,it has overlooked the prevalent friend and adversarial relationships in social networks.This paper addresses this gap by focusing on source localization in signed network models.Leveraging the topological characteristics of signed networks and transforming the propagation probability into effective distance,we propose an optimization method for observer selection.Additionally,by using the reverse propagation algorithm we present a method for information source localization in signed networks.Extensive experimental results demonstrate that a higher proportion of positive edges within signed networks contributes to more favorable source localization,and the higher the ratio of propagation rates between positive and negative edges,the more accurate the source localization becomes.Interestingly,this aligns with our observation that,in reality,the number of friends tends to be greater than the number of adversaries,and the likelihood of information propagation among friends is often higher than among adversaries.In addition,the source located at the periphery of the network is not easy to identify.Furthermore,our proposed observer selection method based on effective distance achieves higher operational efficiency and exhibits higher accuracy in information source localization,compared with three strategies for observer selection based on the classical full-order neighbor coverage. 展开更多
关键词 complex networks signed networks source localization effective distance
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Aerodynamic Effects Compensation on Multi-Rotor UAVs Based on a Neural Network Control Allocation Approach 被引量:4
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作者 Sarah P.Madruga Augusto H.B.M.Tavares +2 位作者 Saulo O.D.Luiz Tiago P.do Nascimento Antonio Marcus N.Lima 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2022年第2期295-312,共18页
This paper shows that the aerodynamic effects can be compensated in a quadrotor system by means of a control allocation approach using neural networks.Thus,the system performance can be improved by replacing the class... This paper shows that the aerodynamic effects can be compensated in a quadrotor system by means of a control allocation approach using neural networks.Thus,the system performance can be improved by replacing the classic allocation matrix,without using the aerodynamic inflow equations directly.The network training is performed offline,which requires low computational power.The target system is a Parrot MAMBO drone whose flight control is composed of PD-PID controllers followed by the proposed neural network control allocation algorithm.Such a quadrotor is particularly susceptible to the aerodynamics effects of interest to this work,because of its small size.We compared the mechanical torques commanded by the flight controller,i.e.,the control input,to those actually generated by the actuators and established at the aircraft.It was observed that the proposed neural network was able to closely match them,while the classic allocation matrix could not achieve that.The allocation error was also determined in both cases.Furthermore,the closed-loop performance also improved with the use of the proposed neural network control allocation,as well as the quality of the thrust and torque signals,in which we perceived a much less noisy behavior. 展开更多
关键词 Aerodynamics effects control allocation minidrone multi-rotor UAV neural networks
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Effects of Reduced Frequency on Network Configuration and Synchronization Transition 被引量:2
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作者 朱留华 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第5期14-17,共4页
Synchronization of networked phase oscillators depends essentially on the correlation between the topological structure of the graph and the dynamical property of the elements. We propose the concept of 'reduced freq... Synchronization of networked phase oscillators depends essentially on the correlation between the topological structure of the graph and the dynamical property of the elements. We propose the concept of 'reduced frequency', a measure which can quantify natural frequencies of each pair of oscillators. Then we introduce an evolving network whose linking rules are controlled by its own dynamical property. The simulation results indicate that when the linking probability positively correlates with the reduced frequency, the network undergoes a first-order phase transition. Meanwhile, we discuss the circumstance under which an explosive synchronization can be ignited. The numerical results show that the peculiar butterfly shape correlation between frequencies and degrees of the nodes contributes to an explosive synchronization transition. 展开更多
关键词 of WORK as IT effects of Reduced Frequency on network Configuration and Synchronization Transition IS that
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Quality assessment of the Topo-Iberia CGPS stations and data quality's effects on postfit ionosphere-free phase residuals
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作者 Juan A.García-Armenteros 《Geodesy and Geodynamics》 EI CSCD 2024年第2期189-199,共11页
This paper analyzed GPS data from the Topo-Iberia network spanning almost 12 years(2008-2020).The data quality information for all 26 Topo-Iberia stations is provided for the first time,complementing the Spanish Geolo... This paper analyzed GPS data from the Topo-Iberia network spanning almost 12 years(2008-2020).The data quality information for all 26 Topo-Iberia stations is provided for the first time,complementing the Spanish Geological Survey’s storage work.Data analyses based on quality indicators obtained using TEQC have been carried out.The guidelines and data quality information from the IGS stations have been considered as the quality references,with the stations ALJI,EPCU,and TIOU standing out as the worst stations,while on the contrary,FUEN,PALM,PILA,and TRIA meet the quality requirements to become an IGS station.The relationship between the GPS data quality and their GAMIT-and Gipsy X-derived postfit ionosphere-free phase residuals has also been investigated,and the results reveal an inversely proportional relationship.It has been found that the stations showing an increase in elevation of the horizon line,also show an increase in cycle slips and multipath,are among the poorest quality stations,and among those with the highest postfit RMS of phase residuals.Moreover,the evolution of the vegetation around the antenna should be considered as it could cause a progressive loss of quality,which is not complying with the IGS standards.The quality assessment shows that the Topo-Iberia stations are appropriate for geodetic purposes,but permanent monitoring would be necessary to avoid the least possible loss of data and quality.In addition,a method to characterize the GNSS data quality is proposed. 展开更多
关键词 GPS dataquality's effects IGS quality standard Postfit LC phase residual Qualityassessment Topo-Iberia CGPS network
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Laboratory Research on Effective Test Area of Short-Crested Waves Generated by Two-Sided Segmented Wavemakers 被引量:1
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作者 李俊 陈刚 +1 位作者 杨建民 彭涛 《China Ocean Engineering》 SCIE EI CSCD 2014年第2期181-192,共12页
The size and shape of the effective test area are crucial to consider when short-crested waves are created by segmented wavemakers. The range of the effective test area of short-crested waves simulated by two-sided se... The size and shape of the effective test area are crucial to consider when short-crested waves are created by segmented wavemakers. The range of the effective test area of short-crested waves simulated by two-sided segmented wavemakers is analyzed in this paper. The experimental investigation on the wave field distribution of short-crested waves generated by two-sided segmented wavemakers is conducted by using an array of wave gauges. Wave spectra and directional spreading function are analyzed and the results show that when the main direction is at a certain angle with the normal line of wave generators, the wave field of 3D short-crested waves generated by two-sided segmented wavemakers has good spatial uniformity within the model test area. The effective test area can provide good wave environments for seakeeping model tests of various ocean engineering structures in the deep ocean engineering basin. 展开更多
关键词 wave simulation 3D short-crested wave effective test area two-sided segmented wavemakers
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Coseismic effects recorded by Fujian subsurface fluid network and its meaning to earthquake prediction 被引量:1
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作者 Lixia Liao Xiaoyin Ni Meiling Wang Shaozu Wu 《Earthquake Science》 CSCD 2009年第3期293-299,共7页
Based on analyses of the spatio-temporal evolutionary characteristics of teleseismic response recorded by Fujian subsurface fluid network and in combination with earthquakes happened in Fujian province during the same... Based on analyses of the spatio-temporal evolutionary characteristics of teleseismic response recorded by Fujian subsurface fluid network and in combination with earthquakes happened in Fujian province during the same period, this paper points out that the step-like rising of water level after distant earthquakes may include some regional stress field information, and the area where water level step-like rises could be the position that the stress concentrated on and where the future earthquakes would occur. If combined with other impending precursors, the location of the events may be predicted to a certain degree. 展开更多
关键词 Fujian subsurface fluid network well water level coseismic effect spatio-temporal evolutionary characteristic water level oscillation
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A Quantitative and Network Approach to Alignment Effects in L2 Continuation Tasks 被引量:2
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作者 Heng CHEN 《Chinese Journal of Applied Linguistics》 2021年第3期399-416,432,共19页
The present study employed a quantitative and network approach to detect alignment effects in second language(L2) continuation tasks designed on the xu-argument(Wang, 2016). The materials used in this study were 6 sub... The present study employed a quantitative and network approach to detect alignment effects in second language(L2) continuation tasks designed on the xu-argument(Wang, 2016). The materials used in this study were 6 sub-corpora consisting of two selected input stories and two groups of L2 written production based on two continuation tasks. During continuation, the participants were required to continue in English a story with its ending removed, with one group reading and continuing the Chinese version and the other group the English version, and then switching their roles in the two tasks. Results show that the alignment effect differs across the two versions of continuation. Specifically, compared with the Chinese-version continuation, L2 learners produced more use of unigrams and bigrams similar to the input story in terms of lexical items, frequency and ranking correlations in the English-version task;on the other hand, the English-version continuation can facilitate generating linguistic networks that are much closer to the native English networks. Moreover, this research corroborates that written production in L2 continuation tasks can be influenced by input content. 展开更多
关键词 CONTINUATION alignment effect language network quantitative linguistics second language acquisition
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Analysis of coverage problem under border effects in wireless sensor networks 被引量:1
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作者 金岩 《High Technology Letters》 EI CAS 2008年第1期61-66,共6页
Wireless sensor networks can be used to monitor the interested region by deploying dense sensor nodes. Coverage is a primary metric to evaluate the capacity of monitoring. In this paper, we focus on the coverage probl... Wireless sensor networks can be used to monitor the interested region by deploying dense sensor nodes. Coverage is a primary metric to evaluate the capacity of monitoring. In this paper, we focus on the coverage problem under border effects, where the sensor nodes are distributed in a circle-shaped region randomly. Under this scenario, we derive the expected coverage of the sensor node and the total network coverage provided by n sensor nodes accurately by probability. These findings are useful to determine the related parameters (sensing range, number of sensor nodes and radius of monitored region) for a specific network coverage ratio. Simulation results demonstrate that our analysis is correct and effective. 展开更多
关键词 wireless sensor networks COVERAGE border effects
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Wavelet network based predistortion method for wideband RF power amplifiers exhibiting memory effects 被引量:1
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作者 JIN Zhe SONG Zhi-huan HE Jia-ming 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第4期625-630,共6页
RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryl... RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryless predistortion cannot linearize PAs effectively. After analyzing PA memory effects, a novel predistortion method based on wavelet networks (WNs) is proposed to linearize wideband RF power amplifiers. A complex wavelet network with tapped delay lines is applied to construct the predistorter and then a complex backpropagation algorithm is developed to train the predistorter parameters. The simulation results show that compared with the previously published feed-forward neural network predistortion method, the proposed method provides faster convergence rate and better performance in reducing out-of-band spectral regrowth. 展开更多
关键词 Power amplifiers. Predistortion. Memory effects. Wavelet networks
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Estimating network effects in China’s mobile telecommunications
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作者 张小强 《Journal of Chongqing University》 CAS 2005年第3期175-178,共4页
A model is proposed along with empirical investigation to prove the existence of network effects in China’s mobile telecommunications market. Futhernore, network effects on China’s mobile telecommunications are esti... A model is proposed along with empirical investigation to prove the existence of network effects in China’s mobile telecommunications market. Futhernore, network effects on China’s mobile telecommunications are estimated with a dynamic model. The structural parameters are identified from regression coefficients and the results are analyzed and compared with another literature. Data and estimation issues are also discussed. Conclusions are drawn that network effects are significant in China’s mobile telecommunications market, and that ignoring network effects leads to bad policy making. 展开更多
关键词 network effects empirical investigation mobile telecommunications
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Small World Effects in a Harmonious Unifying Hybrid Preferential Model Networks
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作者 FANG Jin-Qing BI Qiao LI Yong LU Xin-Biao LIU Qiang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第2X期377-383,共7页
Small worm effects in the harmonious unifying hybrid preferential model (HUHPM) networks are studied both numerically and analytically. The idea and method of the HUHPM is applied to three typical examples of unweig... Small worm effects in the harmonious unifying hybrid preferential model (HUHPM) networks are studied both numerically and analytically. The idea and method of the HUHPM is applied to three typical examples of unweighted BA model, weighted BBV model, and the TDE rnodel, so-called HUHPM-BA, HUHPM-BBV and HUHPM- TDE networks. Comparing the HUHPM with current typical models above, it is found that the HUHPM networks has the smallest average path length and the biggest average clustering coefficient. The results demonstrate that the HUHPM is more suitable not only for the un-iveighted models but also for the weighted models. 展开更多
关键词 harmonious unifying hybrid preferential model small world effect network science
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Predicting Ground Effects of Omnidirectional Antennas in Wireless Sensor Networks
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作者 John F. Janek Jeffrey J. Evans 《Wireless Sensor Network》 2010年第12期879-890,共12页
Omnidirectional antennas are often used for radio frequency (RF) communication in wireless sensor networks (WSNs). Outside noise, electromagnetic interference (EMI), overloaded network traffic, large obstacles (vegeta... Omnidirectional antennas are often used for radio frequency (RF) communication in wireless sensor networks (WSNs). Outside noise, electromagnetic interference (EMI), overloaded network traffic, large obstacles (vegetation and buildings), terrain and atmospheric composition, along with climate patterns can degrade signal quality in the form of data packet loss or reduced RF communication range. This paper explores the RF range reduction properties of a particular WSN designed to operate in agricultural crop fields to collect aggregate data composed of subsurface soil moisture and soil temperature. Our study, using simulation, anechoic and field measurements shows that the effect of antenna placement close to the ground (within 10 cm) signi?cantly changes the omnidirectional transmission pattern. We then develop and propose a prediction method that is more precise than current practices of using the Friis and Fresnel equations. Our prediction method takes into account environmental properties for RF communication range based on the height of nodes and gateways. 展开更多
关键词 OMNIDIRECTIONAL ANTENNA GROUND effects WIRELESS Densor networkS
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An Evaluation of Network Competitiveness and the Effects of LCCs on South Korea’s Network Connectivity:Using Aviation Market Data
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作者 Se-Yeon Jung Baek-Jae Kim Kwang-Eui Yoo 《Journal of Traffic and Transportation Engineering》 2018年第3期109-120,共12页
LCCs(low cost carriers)are expanding their routes,which is affecting airport network connectivity.The subsequent increases in market competition and the number of airlines operating in air network routes have made the... LCCs(low cost carriers)are expanding their routes,which is affecting airport network connectivity.The subsequent increases in market competition and the number of airlines operating in air network routes have made the centrality analysis more significant because it can be used to identify airport network connectivity competitiveness.This study analyzes the network connectivity competitiveness of South Korea among Asian airports using the MIDT(marketing information data transfer)dataset provided by OAG Traffic Analyser,which provides data collected from regional Asian airports since 2011.The network centrality of individual airports is estimated to compare network connectivity competitiveness in Asia.Measures for overall network centrality include degree,closeness and betweenness centrality.This network centrality analysis may be helpful for South Korean airports in identifying their network performance and competitive position in Asia and confirming the effects that LCCs have on airport network connectivity.The results indicate that South Korea’s aviation market needs to expand its network via a strategy that prioritizes the strengthening of airport connectivity and the pursuit of liberalization.In addition,LCC operations will support Korea’s network growth via the various strategies that they employ.Consequently,this in turn will bolster the overall market competitiveness of South Korean airports. 展开更多
关键词 Air network CONNECTIVITY COMPETITIVENESS network CONNECTIVITY CENTRALITY analysis low-cost carrier effects
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