检索结果-南通市图书馆

Optimization of LSTM Ship Trajectory Prediction Based on Hybrid Genetic Algorithm

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Geodesy and Geoinformation Science 2024年第3期7卷 89-102页

作者： ZHAO pengfei Nanjing Marine Radar Institute Nanjing 211153China

Accurate prediction of the movement trajectory of sea surface targets holds significant importance in achieving an advantageous position in the sea battle *** prediction plays a crucial role in ensuring security defense and confrontation,and is essential for effective deployment of military *** predicting the trajectory of sea surface targets using AIS(Automatic Identification System)information is crucial for security defense and confrontation,and holds significant importance for military strategy *** response to the problem of insufficient accuracy in ship trajectory prediction,this study proposes a hybrid genetic algorithm to optimize the Long Short-Term Memory(LSTM)*** HGA-LSTM algorithm is proposed for ship trajectory *** can converge faster and obtain better parameter solutions,thereby improving the effectiveness of ship trajectory *** to traditional LSTM and GA-LSTM algorithms,experimental results demonstrate that this algorithm outperforms them in both single-step and multi-step prediction.

关键词： trajectory prediction LSTM hybrid genetic algorithm

New repairable system model with two types repair based on extended geometric process

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2019年第3期30卷 613-623页

作者： WANG Junyuan YE Jimin XIE pengfei School of Mathematics and Statistics Xidian University

A simple repairable system with one repairman is considered. As the system working age is up to a specified time T, the repairman will repair the component preventively, and it will go back to work as soon as the repair finished. When the system failure, the repairman repair it immediately. The time interval of the preventive repair and the failure correction is described with the extended geometric process. Different from the available replacement policy which is usually based on the failure number or the working age of the system, the bivariate policy (T,N) is considered. The explicit expression of the long-run average cost rate function C(T,N) of the system is derived. Through alternatively minimize the cost rate function C(T,N), the optimal replacement policy (T?,N?) is obtained, and it proves that the optimal policy is unique. Numerical cases illustrate the conclusion, and the sensitivity analysis of the parameters is carried out.

关键词： extended geometric process average cost rate replacement policy renewal reward theorem

Acceptance sampling plan of accelerated life testing for lognormal distribution under time-censoring

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第3期28卷 814-821页

作者： Li Xiaoyang Gao pengfei Sun Fuqiang Science & Technology on Reliability & Environmental Engineering Laboratory Beihang Univeristy

Abstract Lognormal distribution is commonly used in engineering. It is also a life distribution of important research values. For long-life products follow this distribution, it is necessary to apply accelerated testing techniques to product demonstration. This paper describes the development of accelerated life testing sampling plans （ALSPs） for lognormal distribution under time-censoring conditions. ALSPs take both producer and consumer risks into account, and they can be designed to work whether acceleration factor （AF） is known or unknown. When AF is known, lift testing is assumed to be conducted under accelerated conditions with time-censoring. The producer and con- sumer risks are satisfied, and the size of test sample and the size of acceptance number arc opti- mized. Then sensitivity analyses are conducted. When AF is unknown, two or more predetermined levels of accelerated stress are used. The sample sizes and sample proportion allo- cated to each stress level are optimized. The acceptance constant that satisfies producer and consumer risk is obtdned by minimizing the generalized asymptotic variance of the test statistics. Finally, the properties of the two ALSPs （one for known-AF conditions and one for unknown AF conditions） are investigated to show that the proposed method is corrcct and usablc through numerical examples.

关键词： Accelerated life testing Acceleration factor Acceptance sampling Lognormal distribution Producer and consumerrisks Time-censoring

Predictions of ground surface settlement for shield tunnels in sandy cobble stratum based on stochastic medium theory and empirical formulas

在线全文

学校读者我要写书评

暂无评论

Underground Space 2023年第4期11卷 189-203页

作者： Fan Wang Xiuli Du pengfei Li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China

This paper focuses on the prediction of ground surface settlement induced by shield tunnelling in sandy cobble *** on the stochastic medium theory,an analytical solution to predict the surface settlement is developed considering the difference between soil and tunnel volume ***,the effects of tunnel geometries,influence angle and volume loss on the characteristics of surface settlement are *** back analysis,a total of 103 groups of field monitoring data of surface settlement induced by shield tunnelling in sandy cobble stratum are examined to investigate the statistical characteristics of the maximum settlement,settlement trough width and volume *** empirical prediction is presented based on the results of back ***,the analytical solution and empirical expression are validated by the comparisons with the results of model tests and field *** show that the soil at ground surface has an overall dilative response for most of the shield tunnelling in sandy cobble *** addition,the developed analytical solution is applicable and reasonable for surface settlement ***,the proposed empirical formula also shows good per-formance in some cases,providing an approach or a reference for engineering designers to preliminarily evaluate the surface settlement.

关键词： Shield tunnelling Sandy cobble stratum Ground surface settlement Stochastic medium theory Empirical formulas

Dynamic interaction analysis and pairing evaluation in control configuration design

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2016年第7期24卷 861-868页

作者： Xionglin Luo pengfei Cao Feng Xu Department of Automation China University of PetroleumBeijing

This paper presents some new dynamic interaction analysis approaches for square or non-square systems and a pairing evaluation method. For square stable systems, an open-loop approach is proposed, which features the tradeoff between the contributions of response time constant and delay time to relative gain. For non-square stable systems, an extension from the proposed open-loop approach for square systems is presented and the corresponding pairing procedure is given. No interaction analysis approach is perfect for all systems, so any recommended pairing needs to be examined. An evaluation method is proposed in closed-loop with optimal controllers for each loop and whether the pairing is appropriate can be evaluated through testing if the equivalent relative gain is within defined scope. The advantages and effectiveness of proposed interaction analysis approaches and pairing evaluation method are highlighted via several examples of industrial processes.

关键词： Control configurationInteractionPairing evaluationNon-square systemsPID

Decay Rates of the Hyperbolic Equation in an Exterior Domain with Half-Linear and Nonlinear Boundary Dissipations

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2016年第3期29卷 657-680页

作者： LIU Yuxiang LI Jing YAO pengfei Key Laboratory of Systems and Control Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of Sciences School of Mathematical Sciences Shanxi University

This paper considers the energy decay of the wave equation with variable coefficients in an exterior *** damping is put on partly the boundary and partly on the interior of the *** energy decay results are established... 详细信息

关键词： Energy decay exterior domain hyperbolic equation Riemannian geometry method variable coefficients.

Fracture model for the prediction of the electrical percolation threshold in CNTs/Polymer composites

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2018年第1期12卷 125-136页

作者： Yang SHEN pengfei HE Xiaoying ZHUANG School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai China Department of Geotechnical Engineering College of Civil Engineering Tongji University Shanghai China Institute of Continuum Mechanics Leibniz-Universitat Hannover Germany State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University Shanghai China

In this paper, we propose a 3D stochastic model to predict the percolation threshold and the effective electric conductivity of CNTs/Polymer composites. We consider the tunneling effect in our model so that the unrealistic interpenetration can be avoided in the identification of the conductive paths between the CNTs inside the polymer. The results are shown to be in good agreement with reported experimental data.

关键词： electrical percolation CNTs/Polymer composites fracture model electric conductivity tunnelling effects

A study on fatigue damage different compaction using characteristics of asphalt mixture under 3D-microstructural

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2017年第3期11卷 329-337页

作者： Jing HU pengfei LIU Bernhard STEINAUER Institute of Highway Engineering RWTH Aachen University D52074 Aachen Germany

The aim of this paper is investigating the microstructural characteristics of asphalt mixture under different compaction powers. In order to achieve this aim, a test track was built to provide asphalt mixture specimens and X-ray computed tomography （XCT） device was used to scan the internal structure. The aggregate particles and air-voids were extracted using Digital Image Processing （DIP）, so the relationship between compaction and air-voids was determined at first, and then, the effect of aggregate particles on the morphology of air-voids can be evaluated, finally, fatigue properties of asphalt mixture with different air-void ratio were measured by indirect tensile fatigue test as well. The research results release the distribution ofmicrostructures in asphalt pavement. 3D fractal dimension is an effective indicator to quantize the complexity of aggregate particles and air-voids; suffering the same compaction power, aggregates cause different constitutions of air-voids in asphalt mixture; investigation in this paper can present the essential relationship between microstructures and fatigue properties.

关键词： asphalt mixture microstructure morphology digital image processing fatigue damage

Recent Advances in Lead Chemisorption for Perovskite Solar Cells

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2022年第5期28卷 341-357页

作者： pengfei Wu Fei Zhang School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin 300072China

Lead toxicity in perovskite materials,which have hazardous effects on the environment and the human body,has drawn considerable attention to emerging photovoltaic technology perovskite solar *** the capability of other strategies to prevent lead leakage,chemisorption is another efficient approach to block Pb leaching by employing Pb absorbents in/out of device *** review discusses lead toxicity and summarizes the recent research about chemisorption strategies by their functions:additives,the hole-transporting layers,interfacial modifiers,and encapsulation ***,the basic guidelines and challenges for designing novel Pb-ads orbing materials and encapsulation structures are presented.

关键词： Pb toxicity Pb leakage Pb-adsorbing materials Encapsulation layer