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A CNN-Based Single-Stage Occlusion Real-Time Target Detection Method
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作者 Liang Liu Nan Yang +4 位作者 Saifei Liu Yuanyuan Cao Shuowen Tian Tiancheng Liu Xun Zhao 《Journal of Intelligent Learning Systems and Applications》 2024年第1期1-11,共11页
Aiming at the problem of low accuracy of traditional target detection methods for target detection in endoscopes in substation environments, a CNN-based real-time detection method for masked targets is proposed. The m... Aiming at the problem of low accuracy of traditional target detection methods for target detection in endoscopes in substation environments, a CNN-based real-time detection method for masked targets is proposed. The method adopts the overall design of backbone network, detection network and algorithmic parameter optimisation method, completes the model training on the self-constructed occlusion target dataset, and adopts the multi-scale perception method for target detection. The HNM algorithm is used to screen positive and negative samples during the training process, and the NMS algorithm is used to post-process the prediction results during the detection process to improve the detection efficiency. After experimental validation, the obtained model has the multi-class average predicted value (mAP) of the dataset. It has general advantages over traditional target detection methods. The detection time of a single target on FDDB dataset is 39 ms, which can meet the need of real-time target detection. In addition, the project team has successfully deployed the method into substations and put it into use in many places in Beijing, which is important for achieving the anomaly of occlusion target detection. 展开更多
关键词 Real-time Mask Target CNN (Convolutional Neural Network) single-Stage Detection Multi-Scale Feature Perception
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High order single step time delay compensation algorithm for structural active control 被引量:4
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作者 王焕定 耿淑伟 王伟 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2002年第4期336-342,共7页
The optimal instantaneous high order single step algorithm for active control is first discussed and then, the n+1 time step controlling force vector of the instantaneous optimal algorithm is derived from way of n tim... The optimal instantaneous high order single step algorithm for active control is first discussed and then, the n+1 time step controlling force vector of the instantaneous optimal algorithm is derived from way of n time state vector. An estimating algorithm, is developed from this to solve the problem of active control with time delay compensation. The estimating algorithm based on this high order single step β method (HSM) foundation, is proven by simulation and experiment analysis, to be a valid solution to problem of active control with time delay compensation. 展开更多
关键词 active control instantaneous optimal high order single STEP time DELAY COMPENSATION simulation and experiment analysis
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A new approach for time effect analysis of settlement for single pile based on virtual soil-pile model 被引量:9
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作者 吴文兵 王奎华 +1 位作者 张智卿 CHIN Jian Leo 《Journal of Central South University》 SCIE EI CAS 2012年第9期2656-2662,共7页
A new approach is proposed to analyze the settlement behavior for single pile embedded in layered soils. Firstly, soil layers surrounding pile shaft are simulated by using distributed Voigt model, and finite soil laye... A new approach is proposed to analyze the settlement behavior for single pile embedded in layered soils. Firstly, soil layers surrounding pile shaft are simulated by using distributed Voigt model, and finite soil layers under the pile end are assumed to be virtual soil-pile whose cross-section area is the same as that of the pile shaft. Then, by means of Laplace transform and impedance function transfer method to solve the static equilibrium equation of pile, the analytical solution of the displacement impedance fimction at the pile head is derived. Furthermore, the analytical solution of the settlement at the head of single pile is theoretically derived by virtue of convolution theorem. Based on these solutions, the influences of parameters of soil-pile system on the settlement behavior for single pile are analyzed. Also, comparison of the load-settlement response for two well-instrumented field tests in multilayered soils is given to demonstrate the effectiveness and accuracy of the proposed approach. It can be noted that the presented solution can be used to calculate the settlement of single pile for the preliminary design of pile foundation. 展开更多
关键词 SETTLEMENT time effect single pile virtual soil-pile model layered soil VISCOELASTICITY distributed Voigt model
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Getting pre-stack time migration travel times from the single square root operator 被引量:6
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作者 Liu Guofeng Liu Hong +1 位作者 Li Bo Meng Xiaohong 《Applied Geophysics》 SCIE CSCD 2009年第2期129-137,共9页
Improving the focusing capability of pre-stack time migration allows the imaged section to reflect structural characteristics, depth, and interface shape and it is a key step for the preparation of the initial depth m... Improving the focusing capability of pre-stack time migration allows the imaged section to reflect structural characteristics, depth, and interface shape and it is a key step for the preparation of the initial depth migration velocity model. The traditional symmetrical travel time equation is derived based on the assumption of a layered model. It is difficult to achieve the desired effect of focusing in media with strong lateral variation. The nonsymmetrical travel time equation based on Lie algebra and a pseudo-differential operator contains a lateral velocity derivative which can improve the focusing capability even in strongly lateral variable media and also the computation precision of the weight coefficients for relative amplitude preservation. Compared with the symmetrical methods, the nonsymmetrical method is more effective. In this paper, we describe several key steps of nonsymmetric pre-stack travel time calculation and present some test results using synthetic and real data. 展开更多
关键词 single square root operator travel time Lie algebra pseudo-differential operator
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Storage time affects the level and diagnostic efficacy of plasma biomarkers for neurodegenerative diseases
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作者 Lifang Zhao Mingkai Zhang +4 位作者 Qimeng Li Xuemin Wang Jie Lu Ying Han Yanning Cai 《Neural Regeneration Research》 SCIE CAS 2025年第8期2373-2381,共9页
Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is k... Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results. 展开更多
关键词 Alzheimer’s disease amyloid-β diagnostic ability glial fibrillary acidic protein NEURODEGENERATION neurofilament light chain plasma biomarkers single molecule array storage time tau
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Number of Tardy Jobs of Single Machine Scheduling Problem with Variable Processing Time
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作者 朱健梅 《Journal of Modern Transportation》 1999年第1期88-95,共8页
The number of tardy jobs of the single machine scheduling problem with a variable processing time is studied in accordance with the published instances of traffic transportation management engineering. It is proved ... The number of tardy jobs of the single machine scheduling problem with a variable processing time is studied in accordance with the published instances of traffic transportation management engineering. It is proved by 3 partition problem that if the problem is of ready time and common deadline constrained, its complexity is NP hard in the strong sense. Finally, a polynomial algorithm for solving unit processing time and common deadline problems is proposed. 展开更多
关键词 NUMBER of tardy JOBS single machine scheduling problem VARIABLE processing time STRONG NP HARDNESS algorithm.
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A Class of Single Machine Scheduling Problems with Variable Processing Time
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作者 周荷芳 周贤伟 《Journal of Modern Transportation》 2001年第1期93-100,共8页
In this paper, single machine scheduling problems with variable processing time are raised. The criterions of the problem considered are minimizing scheduling length of all jobs, flow time and number of tardy jobs and... In this paper, single machine scheduling problems with variable processing time are raised. The criterions of the problem considered are minimizing scheduling length of all jobs, flow time and number of tardy jobs and so on. The complexity of the problem is determined. [WT5HZ] 展开更多
关键词 single machine scheduling problem NP-HARD variable processing time complexity theory
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Strong NP-Hardness of Single Machine Scheduling Problems with Variable Processing Time
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作者 周贤伟 杜文 朱健梅 《Journal of Modern Transportation》 1998年第2期78-88,共11页
In this paper, single machine scheduling problems with variable processing time is discussed according to published instances of management engineering. Processing time of a job is the product of a “coefficient' ... In this paper, single machine scheduling problems with variable processing time is discussed according to published instances of management engineering. Processing time of a job is the product of a “coefficient' of the job on position i and a “normal' processing time of the job. The criteria considered is to minimize scheduled length of all jobs. A lemma is proposed and proved. In no deadline constrained condition, the problem belongs to polynomial time algorithm. It is proved by using 3 partition that if the problem is deadline constrained, its complexity is strong NP hard. Finally, a conjuncture is proposed that is to be proved. 展开更多
关键词 single machine scheduling problem variable processing time strong NP hardness.
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Parallel Machine Problems with a Single Server and Release Times
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作者 SHILing 《Geo-Spatial Information Science》 2005年第2期148-151,共4页
Parallel machine problems with a single server and release times are generalizations of classical parallel machine problems. Before processing, each job must be loaded on a machine, which takes a certain release times... Parallel machine problems with a single server and release times are generalizations of classical parallel machine problems. Before processing, each job must be loaded on a machine, which takes a certain release times and a certain setup times. All these setups have to be done by a single server, which can handle at most one job at a time. In this paper, we continue studying the complexity result for parallel machine problem with a single and release times. New complexity results are derived for special cases. 展开更多
关键词 parallel machine problem single server release time COMPLEXITY
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Time-Delayed Feedback Control in a Single-Mode Laser System 被引量:1
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作者 GU Xiao-Hui ZHU Shi-Qun WU Dan School of Physical Science and Technology,Suzhou University,Suzhou 215006,China 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第12期1055-1058,共4页
The effects of time-delayed feedback control in a single-mode laser system is investigated.Using the smalltime delay approximation,the analytic expression of the stationary probability distribution function of the las... The effects of time-delayed feedback control in a single-mode laser system is investigated.Using the smalltime delay approximation,the analytic expression of the stationary probability distribution function of the laser field isobtained.The mean,normalized variance and skewness of the steady-state laser intensity are calculated.It is found thatthe time-delayed feedback control can suppress the intensity fluctuation of the laser system.The numerical simulationsare in good agreement with the approximate analytic results. 展开更多
关键词 time-delayed feedback single-mode laser stationary probability distribution function
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A Genetic Algorithm for Single Machine Scheduling with Fuzzy Processing Time and Multiple Objectives
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作者 吴超超 顾幸生 《Journal of Donghua University(English Edition)》 EI CAS 2004年第3期185-189,共5页
In this paper, by considering the fuzzy nature of the data in real-life problems, single machine scheduling problems with fuzzy processing time and multiple objectives are formulated and an efficient genetic algorithm... In this paper, by considering the fuzzy nature of the data in real-life problems, single machine scheduling problems with fuzzy processing time and multiple objectives are formulated and an efficient genetic algorithm which is suitable for solving these problems is proposed. As illustrative numerical examples, twenty jobs processing on a machine is considered. The feasibility and effectiveness of the proposed method have been demonstrated in the simulation. 展开更多
关键词 SCHEDULING single machine genetic algorithms fuzzy processing time multiple objectives
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Noiseless linear amplification for the single-photon entanglement of arbitrary polarization–time-bin qudit 被引量:1
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作者 Ling-Quan Chen Yu-Bo Sheng Lan Zhou 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第1期210-217,共8页
Single-photon entanglement(SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polari... Single-photon entanglement(SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polarization–time-bin qudit from the photon transmission loss caused by the practical channel noise. After the amplification, the fidelity of the SPE can be effectively increased. Meanwhile, the encoded polarization–time-bin features of the qudit can be well preserved. The protocol can be realized under the current experimental conditions. Moreover, the amplification protocol can be extended to resist complete photon loss and partial photon loss during the photon transmission. After the amplification, we can not only increase the fidelity of the target state, but also solve the decoherence problem simultaneously. Based on the above features, our amplification protocol may be useful in future quantum communication. 展开更多
关键词 single-PHOTON ENTANGLEMENT noiseless linear AMPLIFICATION polarization–time-bin QUDIT complete and partial photon loss
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The Influence of the Implementation of Trade Facilitation Systems on the Time Required for Creating Delivery Orders: A Case Study of Tema Port
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作者 Justice Awosonviri Akodia Clement K. Dzidonu +2 位作者 David King Boison Philip Kisembe Joseph Gbandi 《World Journal of Engineering and Technology》 2024年第3期529-539,共11页
This study evaluated the impact of Ghana’s Integrated Customs Management System (ICUMS), implemented within the National Single Window initiative, on the efficiency of issuing Delivery Orders (DO) at Tema Port. Filli... This study evaluated the impact of Ghana’s Integrated Customs Management System (ICUMS), implemented within the National Single Window initiative, on the efficiency of issuing Delivery Orders (DO) at Tema Port. Filling a gap in the existing literature, the research employed a quantitative approach to assess a specific time-related aspect of the cargo clearance process. Employing an Independent t-test on a dataset spanning 2026 Delivery Orders (924 pre-ICUMS and 1102 post-ICUMS) from July 2020 to July 2023, the study investigated ICUMS’s effectiveness in reducing DO issuance time. Results indicate a noteworthy decrease in average DO issuance time, from 11 days pre-implementation to approximately 9 days post-implementation, a reduction validated by statistical analysis through the independent t-test. In light of these findings, the study recommends ongoing refinement of the implementation, reinforcement of trade facilitation measures, and the adoption of best practices from successful global ports. Continuous stakeholder training and regular assessments of ICUMS performance are also endorsed. The study’s implications support the theoretical framework for Single Window systems and carry significant policy implications, emphasizing the need for collaborative efforts to streamline trade facilitation processes driven by Information Technology. Practically, the results serve as a management tool for stakeholders, highlighting areas for targeted interventions to reduce DO issuance times. Methodologically, this research contributes by applying robust statistical analysis to a specific component within the Time Release Study framework, offering a nuanced understanding of trade facilitation systems’ effectiveness in improving cargo clearance processes. 展开更多
关键词 Cargo Clearance Container Dwell time single Window Trade Facilitation
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Exploring the hepatitis C virus genome using single molecule realtime sequencing 被引量:2
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作者 Haruhiko Takeda Taiki Yamashita +1 位作者 Yoshihide Ueda Akihiro Sekine 《World Journal of Gastroenterology》 SCIE CAS 2019年第32期4661-4672,共12页
Single molecular real-time(SMRT)sequencing,also called third-generation sequencing,is a novel sequencing technique capable of generating extremely long contiguous sequence reads.While conventional short-read sequencin... Single molecular real-time(SMRT)sequencing,also called third-generation sequencing,is a novel sequencing technique capable of generating extremely long contiguous sequence reads.While conventional short-read sequencing cannot evaluate the linkage of nucleotide substitutions distant from one another,SMRT sequencing can directly demonstrate linkage of nucleotide changes over a span of more than 20 kbp,and thus can be applied to directly examine the haplotypes of viruses or bacteria whose genome structures are changing in real time.In addition,an error correction method(circular consensus sequencing)has been established and repeated sequencing of a single-molecule DNA template can result in extremely high accuracy.The advantages of long read sequencing enable accurate determination of the haplotypes of individual viral clones.SMRT sequencing has been applied in various studies of viral genomes including determination of the full-length contiguous genome sequence of hepatitis C virus(HCV),targeted deep sequencing of the HCV NS5A gene,and assessment of heterogeneity among viral populations.Recently,the emergence of multi-drug resistant HCV viruses has become a significant clinical issue and has been also demonstrated using SMRT sequencing.In this review,we introduce the novel third-generation PacBio RSII/Sequel systems,compare them with conventional next-generation sequencers,and summarize previous studies in which SMRT sequencing technology has been applied for HCV genome analysis.We also refer to another long-read sequencing platform,nanopore sequencing technology,and discuss the advantages,limitations and future perspectives in using these thirdgeneration sequencers for HCV genome analysis. 展开更多
关键词 Third generation SEQUENCING PacBio RSII single molecule real-time SEQUENCING HEPATITIS C virus Resistance-associated SUBSTITUTION NANOPORE sequencer
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Real-Time Method for Detecting Harmonic and Reactive Currents of Single-Phase Circuits 被引量:1
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作者 张秀峰 丁菊霞 《Journal of Southwest Jiaotong University(English Edition)》 2006年第2期135-141,共7页
According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze's power definition is proposed. Th... According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze's power definition is proposed. The results of theoretical analysis and simula- tion show that the proposed method is effective in realtime detecting of instantaneous harmonic and reactive currents in single-phase circuits. When only detecting the total reactive currents, this method does not need a phase-locked loop circuit, and it also can be used in some special applications to provide different compensations on the ground of different requirements of electric network. Compared with the other methods based on the theory of instantaneous reactive power, this method is simple and easy to realize. 展开更多
关键词 Active filter HARMONIC Reactive current Real-time detection single-phase circuit Electric-network
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Invariant operator theory for the single-photon energy in time-varying media
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作者 Choi Jeong-Ryeol 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第1期56-60,共5页
After the birth of quantum mechanics, the notion in physics that the frequency of light is the only factor that determines the energy of a single photon has played a fundamental role. However, under the assumption tha... After the birth of quantum mechanics, the notion in physics that the frequency of light is the only factor that determines the energy of a single photon has played a fundamental role. However, under the assumption that the theory of Lewis-Riesenfeld invariants is applicable in quantum optics, it is shown in the present work that this widely accepted notion is valid only for light described by a time-independent Hamiltonian, i.e., for light in media satisfying the conditions, ε(t) = ε(0), u(t) = u(0), and σ(t) = 0 simultaneously. The use of the Lewis Riesenfeld invariant operator method in quantum optics leads to a marvelous result: the energy of a single photon propagating through time-varying linear media exhibits nontrivial time dependence without a change of frequency. 展开更多
关键词 single-photon energy invariant operator theory time-varying media
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An Improved Ant Colony Algorithm for a Single-machine Scheduling Problem with Setup Times
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作者 YE Qiang LIU Xinbao LIU Lin YANG Shanglin School of Management,Hefei University of Technology,Hefei 230009,China, 《武汉理工大学学报》 CAS CSCD 北大核心 2006年第S3期956-961,共6页
Motivated by industrial applications we study a single-machine scheduling problem in which all the jobs are mutu- ally independent and available at time zero.The machine processes the jobs sequentially and it is not i... Motivated by industrial applications we study a single-machine scheduling problem in which all the jobs are mutu- ally independent and available at time zero.The machine processes the jobs sequentially and it is not idle if there is any job to be pro- cessed.The operation of each job cannot be interrupted.The machine cannot process more than one job at a time.A setup time is needed if the machine switches from one type of job to another.The objective is to find an optimal schedule with the minimal total jobs’completion time.While the sum of jobs’processing time is always a constant,the objective is to minimize the sum of setup times.Ant colony optimization(ACO)is a meta-heuristic that has recently been applied to scheduling problem.In this paper we propose an improved ACO-Branching Ant Colony with Dynamic Perturbation(DPBAC)algorithm for the single-machine schedul- ing problem.DPBAC improves traditional ACO in following aspects:introducing Branching Method to choose starting points;im- proving state transition rules;introducing Mutation Method to shorten tours;improving pheromone updating rules and introduc- ing Conditional Dynamic Perturbation Strategy.Computational results show that DPBAC algorithm is superior to the traditional ACO algorithm. 展开更多
关键词 DPBAC ALGORITHM ANT COLONY optimization ALGORITHM single-MACHINE SCHEDULING problem SETUP time
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Electromagnetic response function for the semi-annual variations estimated by the single-station method using the night-time values of the geomagnetic fields
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作者 陈伯舫 《Acta Seismologica Sinica(English Edition)》 CSCD 2000年第3期316-324,共9页
The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estim... The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estimate the Q1 value using the single-station Z/H method. This technique enables us to carry out regional deep gcomagnetic sounding by the method. The data used for analyses are geomagnetic night-time values for about, typically, 26 years from 5 good-quality stations and for several years from 34 stations distributed over the globe. The results indicate that the night-time values yield more reliable response estimates for half-year period compared to the usual estimates obtained from daily means. It implies that the approximation for the night-time fields holds good for the half-year period, but the daily means are not suitable for estimating the response function of the semi-annual variations by using the single-station method. Source field analyses for daily means data and night-time means data have also been carried out in this paper. 展开更多
关键词 geomagnetic night-time data semi-annual variations electromagnetic response functions single-station Z/H method
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Application of Smith Predictor Based on Single Neural Network in Cold Rolling Shape Control 被引量:15
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作者 WANG Yiqun SUN FD +2 位作者 LIU Jian SUN Menghui XIE Yihan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2009年第2期282-286,共5页
Flatness is one of the most important criterion factors to evaluate the quality of the steel strip. To improve the strip' s flatness quality, the most frequently used methodology is to employ the closed-loop automati... Flatness is one of the most important criterion factors to evaluate the quality of the steel strip. To improve the strip' s flatness quality, the most frequently used methodology is to employ the closed-loop automatic shape control system. However, in the shape control system, the shape-meter is always installed at the down way of the exit of the cold rolling mill and can not sense the changes of the strip flatness in the rolling gap directly. This kind of installation results in the delay of the feedback in the control system. Therefore, the stability and response performance of the system are strongly affected by the delay. At present, there is still no mature way to design controllers for systems with time delay. Although the conventional PID controller used in most practical applications has the capability to compensate the delay, the effect of the compensation is limited, especially for the systems with long time delay. Smith predictor, as a compensator for solving this problem, is now widely used in industry systems. However, the request of highly precise model of the system and the poor adaptive performance to the changes of related parameters limit the application of the Smith predictor in practice. In order to overcome the drawbacks of the Smith predictor, a new Smith predictor based on single neural network PID (SNN-PID) is proposed. Because the single neural network is employed into the Smith predictor to improve the controller's self-adaptability, the adaptive capability to the varying parameters of the system is improved. Meanwhile, for the purpose of solving the problems such as time-consuming and complicated calculation of the neural networks in real time, the learning coefficient of neural network is divided into several stages as usually done in expert control system. Therefore, the control system can obtain fast response due to the improved calculation speed of the neural networks. In order to validate the performance of the proposed controller, the experiment is conducted on the shape control system in a 300 mm four-high reversing cold rolling mill. The experimental results show that the SNN-PID with Smith predictor controller can effectively compensate the delay effects and achieve better control performance than the conventional PID controller. 展开更多
关键词 shape control time delay single neural network Smith predictor
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An efficient source wavefield reconstruction scheme using single boundary layer values for the spectral element method 被引量:3
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作者 YouShan Liu Tao Xu +3 位作者 YangHua Wang JiWen Teng José Badal HaiQiang Lan 《Earth and Planetary Physics》 CSCD 2019年第4期342-357,共16页
In the adjoint-state method, the forward-propagated source wavefield and the backward-propagated receiver wavefield must be available simultaneously either for seismic imaging in migration or for gradient calculation ... In the adjoint-state method, the forward-propagated source wavefield and the backward-propagated receiver wavefield must be available simultaneously either for seismic imaging in migration or for gradient calculation in inversion. A feasible way to avoid the excessive storage demand is to reconstruct the source wavefield backward in time by storing the entire history of the wavefield in perfectly matched layers. In this paper, we make full use of the elementwise global property of the Laplace operator of the spectral element method (SEM) and propose an efficient source wavefield reconstruction method at the cost of storing the wavefield history only at single boundary layer nodes. Numerical experiments indicate that the accuracy of the proposed method is identical to that of the conventional method and is independent of the order of the Lagrange polynomials, the element type, and the temporal discretization method. In contrast, the memory-saving ratios of the conventional method versus our method is at least N when using either quadrilateral or hexahedron elements, respectively, where N is the order of the Lagrange polynomials used in the SEM. A higher memorysaving ratio is achieved with triangular elements versus quadrilaterals. The new method is applied to reverse time migration by considering the Marmousi model as a benchmark. Numerical results demonstrate that the method is able to provide the same result as the conventional method but with about 1/25 times lower storage demand. With the proposed wavefield reconstruction method, the storage demand is dramatically reduced;therefore, in-core memory storage is feasible even for large-scale three-dimensional adjoint inversion problems. 展开更多
关键词 spectral element METHOD SOURCE wavefield reconstruction single boundary layer memory-saving ratio ADJOINT METHOD reverse time migration
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