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Density Map Guided Region Localization for End-to-End Small Object Detection

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Journal of Systems Science and Information 2023年第6期11卷 776-794页

作者： Bo li Kai HUANG Junhui Li Yufu liAO Sichuan Jiuzhou Aerocont Technologies Co. Ltd.Mianyang 621000China

With the advancement of society and science and technology, the demand for detecting small objects in practical scenarios becomes stronger. Such objects are only represented by relatively small coverage of pixels, and the features are degraded severely after being extracted by a deep convolutional neural network, which is detrimental to the detection performance for small objects. Therefore, an intuitive solution is to increase the resolution of small objects by cropping the original image. In this paper, we propose a simple but effective object density map guided region localization module (DMGRL) to locate and crop the regions of interest where small objects may exist. Firstly, the density map of the objects is estimated by object density map estimation network, and then the coordinates of the small object regions are calculated;Secondly, the continuous differentiable affine transformation is utilized to crop these regions so that the detector with DMGRL can be trained end-to-end instead of two-stage training. Finally, the all prediction results of input image and cropped region images are merged together to output the final detection results by non maximum suppression (NMS). Extensive experiments demonstrate the superior performance of the detector incorporated DMGRL.

关键词： small object detection density map estimation end-to-end training affine transformation

Improving neural sentence alignment with word translation

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Frontiers of Computer Science 2021年第1期15卷 81-90页

作者： Ying DING Junhui Li Zhengxian GONG Guodong ZHOU School of Computer Science and Technology Soochow UniversitySuzhou 215006China

Sentence alignment is a basic task in natural lan-guage processing which aims to extract high-quality paral-lel sentences automatically.Motivated by the observation that aligned sentence pairs contain a larger number of aligned words than unaligned ones,we treat word translation as one of the most useful external knowledge.In this paper,we show how to explicitly integrate word translation into neural sentence alignment.Specifically,this paper proposes three cross-lingual encoders to incorporate word translation:1)Mixed Encoder that learns words and their translation annotation vectors over sequences where words and their translations are mixed alterma-tively;2)Factored Encoder that views word translations as fea-tures and encodes words and their translations by concatenating their embeddings;and 3)Gated Encoder that uses gate mechanism to selectively control the amount of word translations moving forward.Experimentation on NIST MT and Opensub-titles Chinese-English datasets on both non-monotonicity and monotonicity scenarios demonstrates that all the proposed encoders significantly improve sentence alignment performance.

关键词： sentence alignment word translation mixeden coder factored encoder gated encoder

Dynamic economic evaluation of hundred megawatt-scale electrochemical energy storage for auxiliary peak shaving

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Protection and Control of Modern Power Systems 2023年第3期8卷 252-269页

作者： Junhui Li Gang Mu Jiahui Zhang Cuiping li Gangui Yan Haotian Zhang Guohang Chen Key Laboratory of Modern Power System Simulation and Control and Renewable Energy Technology Ministry of Education(Northeast Electric Power University)Jilin 132012China State Grid Zhejiang Pinghu City Electric Power Supply Company.LTD. Pinghu 314200Zhejiang ProvinceChina.

With the rapid development of wind power,the pressure on peak regulation of the power grid is increased.Electro-chemical energy storage is used on a large scale because of its high efficiency and good peak shaving and valley fill-ing ability.The economic benefit evaluation of participating in power system auxiliary services has become the focus of attention since the development of grid-connected hundred megawatt-scale electrochemical energy storage systems(ESS).Based on the relationship between power and capacity in the process of peak shaving and valley filling,a dynamic economic benefit evaluation model of peak shaving assisted by hundred megawatt-scale electrochemi-cal ESS considering the equivalent life of the battery is proposed.The model considers the investment cost of energy storage,power efficiency,and operation and maintenance costs,and analyzes the dynamic economic benefits of dif-ferent energy storage technologies participating in the whole life cycle of the power grid.Then,according to the cur-rent ESS market environment,the auxiliary service compensation price,peak-valley price difference and energy stor-age cost unit price required to make the energy storage technology achieve the balance of payments are calculated,and the economic balance points of different energy storage types are clarified.Finally,based on the measured data of different provincial power grids,the economies of six energy storage types applied to three provincial power grids are compared and analyzed,and the rationality and effectiveness of the relevant models proposed are verified.The work has theoretical guiding significance for the economic benefit evaluation of hundred megawatt-scale electro-chemical energy storage.Highlights 1 A proportional relationship between grid filling power and capacity demand is proposed.It is used to determine the energy storage configuration for auxiliary peak shaving.2 A dynamic economic evaluation model considering energy storage investment and maintenance costs,electric-ity profit,and auxiliary

关键词： auxiliary valley electrochemical

Structural design and modal behaviors analysis of a new swept baffled inflatable wing

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Defence Technology（防务技术） 2023年第6期24卷 382-398页

作者： Nuo Ma li liu Fanmin Meng junhui Meng School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081PR China

Inflatable wing has significant application value in the design of loitering munitions because of its advantages such as lightweight and foldability.However,due to the flexible characteristics,aeroelastic behaviors of inflatable wings such as flutter are nonnegligible in flight.By designing a certain angle between the inflatable beam and the wing span,the structural dynamic and even the aeroelastic performance of the inflatable wing can be effectively improved.Based on the analysis of the mechanical and geometric characteristics of the inflatable structure,a new inflatable wing with sweep arranged inflatable beams is proposed,and the main design variables and methods are analyzed.For purpose of investigating the aeroelastic performance of the swept baffled inflatable wing,the modal behaviors by considering the wet mode are studied.In consideration of the deficiencies of the traditional wet modal analysis method,by introducing the influence on the additional stiffness of flow field,an added massstiffness method is proposed in this paper,and the advantages are verified by ground vibration experiments.On this basis,the effects of baffles sweep angle,pressure,and boundary conditions on the modal parameters and aeroelastic performance of inflatable wing are analyzed.The results show that the aeroelastic performance of the inflatable wing can be designed by changing the baffles sweep angle,which is enlightened for the aeroelastic tailoring design on inflatable wings.

关键词： Inflatable wing Structural design Wet mode Flutter analysis

Modeling of Large-Scale Hydrogen Storage System Considering Capacity Attenuation and Analysis of Its Efficiency Characteristics

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Energy Engineering 2024年第2期121卷 291-313页

作者： Junhui Li Haotian Zhang Cuiping li Xingxu Zhu Ruitong liu Fangwei Duan Yongming Peng Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology Ministry of Education(Northeast Electric Power University)Jilin132012China Ministry of Science and Technology Electric Power Research Institute of State Grid Liaoning Electric Power Co.Ltd.Shenyang110006China Northeast Electric Power Dispatching Control Center Northeast Branch of State Grid Corporation of ChinaShenyang110180China

In the existing power system with a large-scale hydrogen storage system,there are problems such as low efficiency of electric-hydrogen-electricity conversion and single modeling of the hydrogen storage system.In order to improve the hydrogen utilization rate of hydrogen storage system in the process of participating in the power grid operation,and speed up the process of electric-hydrogen-electricity conversion.This article provides a detailed introduction to the mathematical and electrical models of various components of the hydrogen storage unit,and also establishes a charging and discharging efficiency model that considers the temperature and internal gas partial pressure of the hydrogen storage unit.These models are of great significance for studying and optimizing gas storage technology.Through these models,the performance of gas storage units can be better understood and improved.These studies are very helpful for improving energy storage efficiency and sustainable development.The factors affecting the charge-discharge efficiency of hydrogen storage units are analyzed.By integrating the models of each unit and considering the capacity degradation of the hydrogen storage system,we can construct an efficiency model for a large hydrogen storage system and power conversion system.In addition,the simulation models of the hydrogen production system and hydrogen consumption system were established in MATLAB/Simulink.The accuracy and effectiveness of the simulation model were proved by comparing the output voltage variation curve of the simulation with the polarization curve of the typical hydrogen production system and hydrogen consumption system.The results show that the charge-discharge efficiency of the hydrogen storage unit increases with the increase of operating temperature,and H2 and O2 partial voltage have little influence on the charge-discharge efficiency.In the process of power conversion system converter rectification operation,its efficiency decreases with the increase of temperature,while in the proc

关键词： Hydrogen storage system simulation modeling electrolyzer fuel cell capacity loss

Evaluation of the performance of GNSS-based velocity estimation algorithms

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Satellite Navigation 2022年第3期3卷 162-177,I0004页

作者： li Ji Rui Sun Qi Cheng junhui Wang College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing211106China

Global Navigation Satellite System(GNSS)based velocity estimation is one of the most cost-effective and widely used methods in determining velocity in geodesy and transport applications.Highly accurate and reliable velocity measurements can be obtained by exploiting the raw Doppler,carrier phase,and pseudorange measurements with a GNSS receiver.There are several approaches to GNSS-based velocity determination.This paper investigates the characteristics of the approaches which are currently popular and applicable to the observations of Global Positioning System(GPS),BeiDou Navigation Satellite System(BDS),and their combination(GPS/BDS).Specifically,it evaluates the performance of the velocity estimated based on the Raw Doppler method,the Time-Differenced Pseudorange method,the Time-Differenced Carrier Phase method,and the Double-Differenced Carrier Phase method,in both static and dynamic modes and in open and urban scenarios.The experiments show that BDS has the advantages in delivering accurate velocity determinations over GPS in the Asia–Pacific region,and the effectiveness of the GPS/BDS in improving the overall accuracy of velocity determination in complex urban scenarios.

关键词： GNSS BDS GPS Vehicle velocity determination

Desorption hysteresis of coalbed methane and its controlling factors: a brief review

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Frontiers of Earth Science 2021年第2期15卷 224-236页

作者： Weikai XU Junhui Li Xiang WU Du liU Zhuangsen WANG College of Geoscience and Surveying Engineering China University of Mining and TechnologyBeijing 100083China China Coalbed Methane Co.Ltd Beijing 100011China

Most coal reservoirs show high gas content with relatively low desorption efficiency,which restricts the efficiency of coalbed methane(CBM)extraction and single-well productivity.This review highlights the desorption hysteresis mechanism and its controlling factors as well as methods and models to reveal desorption hysteresis and potential solutions.Methane adsorption and desorption can be recorded by both gravimetric and volumetric experiments.Although different adsorption models are used,desorption is generally considered with the Langmuir model.Desorption hysteresis is influenced by the petrophysical composition,thermal maturity,pore structure distribution of the coal,reservoir temperature,and moisture and water content.Methods for calculating desorption hysteresis include the area index,hysteresis index and introduction of a hysteresis factor and a hysteresis coefficient.Molecular dynamics simulations of methane desorption are mainly based on theories of kinetics,thermodynamics,and potential energy.The interaction forces operating among coal,water,and methane molecules can be calculated from microscopic intermolecular forces(van der Waals forces).The desorption hysteresis mechanism and desorption process still lack quantitative probe methodologies,and future research should focus on coal wettability under the constraints of liquid content,potential energy adjustment mechanism,and quantitative analysis of methane desorption rates.Further research is expected to reveal the desorption kinetics of methane through the use of the solid–liquid–gas three-phase coupling theory associated with the quantitative analysis of methane desorption hysteresis,thereby enhancing the recovery rate and efficiency of CBM wells.

关键词： desorption hysteresis diffusion process kinetics multiphase coupling coalbed methane production

Influence of Piston Number on Churning Losses in Axial Piston Pumps

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 194-207页

作者： Ying li Xing Chen Hao Luo junhui Zhang Jin Zhang School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China State Key Laboratory of Fluid Power Transmission and Control Zhejiang UniversityHangzhou 310027China

Raising the rotational speed of an axial piston pump is useful for improving its power density;however,the churning losses of the piston increase significantly with increasing speed,and this reduces the performance and efficiency of the axial piston pump.Currently,there has been some research on the churning losses of pistons;however,it has rarely been analyzed from the perspective of the piston number.To improve the performance and efficiency of the axial piston pump,a computational fluid dynamics(CFD)simulation model of the churning loss was established,and the effect of piston number on the churning loss was studied in detail.The simulation analysis results revealed that the churning losses initially increased as the number of pistons increased;however,when the number of pistons increased from six to nine,the torque of the churning losses decreased because of the hydrodynamic shadowing effect.In addition,in the analysis of cavitation results,it was determined that the cavitation area of the axial piston pump was mainly concentrated around the piston,and the cavitation became increasingly severe as the speed increased.By comparing the simulation results with and without the cavitation model,it was observed that the cavitation phenomenon is beneficial for the reduction of churning losses.In this study,a piston churning loss test rig that can eliminate other friction losses was established to verify the accuracy of the simulation results.A comparative analysis indicated that the simulation results were consistent with the actual situation.In addition,this study also conducted a simulation study on seven and nine piston pumps with the same displacement.The simulation results revealed that churning losses of the seven pistons were generally greater than those of the nine pistons under the same displacement.In addition,regarding the same piston number and displacement,reducing the pitch circle radius of piston bores is effective in reducing the churning loss.This research analyzes the effect of piston number on the

关键词： Axial piston pumps Churning losses Pistons CFD simulations Experimental study

Model Identification of The Skid-steered Wheeled Vehicle at Operating Point

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Model Identification of The Skid-steered Wheeled Vehicle at ...