检索结果-南通市图书馆

Variable Clearance Characteristics of High Subsonic Compressor Cascades with Blade Tip Winglets

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2022年第2期31卷 495-510页

作者： WU Wanyang ZHONG Jingjun Merchant Marine College Shanghai Maritime UniversityShanghai 201306China

The gas turbine is the main power equipment for naval ship and special civil ship,while the compressor is one of the core structures of the gas turbine.The existing tip clearance could prevent the compressor blade and casing collision.Therefore,the flow loss in the tip region caused by the tip clearance will degrade the performance of the compressor.To improve the variable clearance characteristics of the high subsonic compressor cascades,the cascades with tip clearances of 1%,2%and 3%chord length are studied through experimental measurements and numerical calculations.The research results prove that the pressure surface tip winglet can cause a significant improvement effect under most working conditions.If the blade tip clearance size is gradually increasing within a reasonable range,the improvement effect becomes more remarkable,and the optimal tip winglet case changes.When tip clearance is 1%chord length,the PTW1.0 case(the width of the pressure surface tip winglet is 1.0 time of the original tip)reduces the flow loss by 3.09%compared with the NTW case(No Tip Winglet).When tip clearance is 2%chord length,the flow loss of PTW1.5 case(the width of the pressure surface tip winglet is 1.5 times of the original tip)is reduced by 3.46%.When tip clearance is 3%chord length,all alternative tip winglets reduce the total pressure loss,and PTW2.0 case(the width of the pressure surface tip winglet is 2.0 times of the original tip)is the best choice,which has a 6.53%degree of improvement.

关键词： high subsonic compressor blade tip winglet tip clearance pressure surface experimental measurement

DAAPS: A Deformable-Attention-Based Anchor-Free Person Search Model

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第11期77卷 2407-2425页

作者： Xiaoqi Xin Dezhi Han Mingming Cui School of Information Engineering Shanghai Maritime UniversityShanghai201306China

Person Search is a task involving pedestrian detection and person re-identification,aiming to retrieve person images matching a given objective attribute from a large-scale image library.The Person Search models need to understand and capture the detailed features and context information of smaller objects in the image more accurately and comprehensively.The current popular Person Search models,whether end-to-end or two-step,are based on anchor boxes.However,due to the limitations of the anchor itself,the model inevitably has some disadvantages,such as unbalance of positive and negative samples and redundant calculation,which will affect the performance of models.To address the problem of fine-grained understanding of target pedestrians in complex scenes and small sizes,this paper proposes a Deformable-Attention-based Anchor-free Person Search model(DAAPS).Fully Convolutional One-Stage(FCOS),as a classic Anchor-free detector,is chosen as the model’s infrastructure.The DAAPS model is the first to combine the Anchor-free Person Search model with Deformable Attention Mechanism,applied to guide the model adaptively adjust the perceptual.The Deformable Attention Mechanism is used to help the model focus on the critical information and effectively improve the poor accuracy caused by the absence of anchor boxes.The experiment proves the adaptability of the Attention mechanism to the Anchor-free model.Besides,with an improved ResNeXt+network frame,the DAAPS model selects the Triplet-based Online Instance Matching(TOIM)Loss function to achieve a more precise end-to-end Person Search task.Simulation experiments demonstrate that the proposed model has higher accuracy and better robustness than most Person Search models,reaching 95.0%of mean Average Precision(mAP)and 95.6%of Top-1 on the CUHK-SYSU dataset,48.6%of mAP and 84.7%of Top-1 on the Person Re-identification in the Wild(PRW)dataset,respectively.

关键词： Person Search anchor-free attention mechanism person detection pedestrian re-identification

DTHN: Dual-Transformer Head End-to-End Person Search Network

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第10期77卷 245-261页

作者： Cheng Feng Dezhi Han Chongqing Chen School of Information Engineering Shanghai Maritime UniversityShanghai201306China

Person search mainly consists of two submissions,namely Person Detection and Person Re-identification(reID).Existing approaches are primarily based on Faster R-CNN and Convolutional Neural Network(CNN)(e.g.,ResNet).While these structures may detect high-quality bounding boxes,they seem to degrade the performance of re-ID.To address this issue,this paper proposes a Dual-Transformer Head Network(DTHN)for end-to-end person search,which contains two independent Transformer heads,a box head for detecting the bounding box and extracting efficient bounding box feature,and a re-ID head for capturing high-quality re-ID features for the re-ID task.Specifically,after the image goes through the ResNet backbone network to extract features,the Region Proposal Network(RPN)proposes possible bounding boxes.The box head then extracts more efficient features within these bounding boxes for detection.Following this,the re-ID head computes the occluded attention of the features in these bounding boxes and distinguishes them from other persons or backgrounds.Extensive experiments on two widely used benchmark datasets,CUHK-SYSU and PRW,achieve state-of-the-art performance levels,94.9 mAP and 95.3 top-1 scores on the CUHK-SYSU dataset,and 51.6 mAP and 87.6 top-1 scores on the PRW dataset,which demonstrates the advantages of this paper’s approach.The efficiency comparison also shows our method is highly efficient in both time and space.

关键词： Transformer occluded attention end-to-end person search person detection person re-ID Dual-Transformer Head

Swin-PAFF: A SAR Ship Detection Network with Contextual Cross-Information Fusion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第11期77卷 2657-2675页

作者： Yujun Zhang Dezhi Han Peng Chen School of Information Engineering Shanghai Maritime UniversityShanghai201306China

Synthetic Aperture Radar(SAR)image target detection has widespread applications in both military and civil domains.However,SAR images pose challenges due to strong scattering,indistinct edge contours,multi-scale representation,sparsity,and severe background interference,which make the existing target detection methods in low accuracy.To address this issue,this paper proposes a multi-scale fusion framework(Swin-PAFF)for SAR target detection that utilizes the global context perception capability of the Transformer and the multi-layer feature fusion learning ability of the feature pyramid structure(FPN).Firstly,to tackle the issue of inadequate perceptual image context information in SAR target detection,we propose an end-to-end SAR target detection network with the Transformer structure as the backbone.Furthermore,we enhance the ability of the Swin Transformer to acquire contextual features and cross-information by incorporating a Swin-CC backbone network model that combines the Spatial Depthwise Pooling(SDP)module and the self-attentive mechanism.Finally,we design a cross-layer fusion neck module(PAFF)that better handles multi-scale variations and complex situations(such as sparsity,background interference,etc.).Our devised approach yields a noteworthy AP@0.5:0.95 performance of 91.3%when assessed on the HRSID dataset.The application of our proposed technique has resulted in a noteworthy advancement of 8%in the AP@0.5:0.95 scores on the HRSID dataset.

关键词： Transformer deep learning SAR object detection ship detection

Recent Trends of In-Vehicle Time Sensitive Networking Technologies, Applications and Challenges

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国通信:英文版 2023年第11期20卷 30-55页

作者： Yanli Xu Jian Shang Hao Tang School of Information Engineering Shanghai Maritime UniversityShanghai 201306China

With the vigorous development of automobile industry,in-vehicle network is also constantly upgraded to meet data transmission requirements of emerging applications.The main transmission requirements are low latency and certainty especially for autonomous driving.Time sensitive networking(TSN)based on Ethernet gives a possible solution to these requirements.Previous surveys usually investigated TSN from a general perspective,which referred to TSN of various application fields.In this paper,we focus on the application of TSN to the in-vehicle networks.For in-vehicle networks,we discuss all related TSN standards specified by IEEE 802.1 work group up to now.We further overview and analyze recent literature on various aspects of TSN for automotive applications,including synchronization,resource reservation,scheduling,certainty,software and hardware.Application scenarios of TSN for in-vehicle networks are analyzed one by one.Since TSN of in-vehicle network is still at a very initial stage,this paper also gives insights on open issues,future research directions and possible solutions.

关键词： automobile industry deterministic transmission in-vehicle network low latency time sensitive networking(TSN)

Multiobjective Optimization of Hull Form Based on Global Optimization Algorithm

在线全文

学校读者我要写书评

暂无评论

Journal of shanghai Jiaotong university(Science) 2022年第3期27卷 346-355页

作者：刘洁张宝吉 Merchant Marine College Shanghai Maritime UniversityShanghai 201306China College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai 201306China

Rankine source method,optimization technology,parametric modeling technology,and improved multiobjective optimization algorithm were combined to investigate the multiobjective optimization design of hull form.A multiobjective and multilevel optimization design framework was constructed for the comprehensive navigation performance of ships.CAESES software was utilized as the optimization platform,and nondominated sorting genetic algorithm II(NSGA-II)was used to conduct multiobjective optimization research on the resistance and sea-keeping performance of the ITTC Ship A-2 fishing vessel.Optimization objectives of this study are heave/pitch response amplitude and wave-making resistance.Taking the displacement and the length between perpendiculars as constraints,we optimized the profile of the hull.Analytic hierarchy process(AHP)and technique for order preference by similarity to ideal solution(TOPSIS)were used to sort and select Pareto solutions and determine weight coefficient of each navigation performance objective in the general objective.Finally,the hydrodynamic performance before and after the parametric deformation of the hull was compared.The results show that both the wave-making resistance and heave/pitch amplitude of the optimized hull form are reduced,and the satisfactory optimal hull form is obtained.The results of this study have a certain reference value for the initial stage of multiobjective optimization design of hull form.

关键词： multiobjective optimization Rankine source method global optimization algorithm nondominated sorting genetic algorithm II(NSGA-II)

A Novel Obstacle Avoidance Consensus Control for Multi-AUV Formation System

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2023年第5期10卷 1304-1318页

作者： Linling Wang Daqi Zhu Wen Pang Chaomin Luo the shanghai Engineering Research Center of Intelligent maritime Search&Rescue and Underwater Vehicles Shanghai Maritime UniversityShanghai 201306China the Shanghai Maritime University Shanghai 201306China the School of Mechanical Engineering University of Shanghai for Science and TechnologyShanghai 200093China the Department of Electrical and Computer Engineering Mississippi State UniversityMississippi StateMS 39762 USA

In this paper, the fixed-time event-triggered obstacle avoidance consensus control for a multi-AUV time-varying formation system in a 3D environment is presented by using an improved artificial potential field and leader-follower strategy(IAPF-LF). Firstly, the proposed fixed-time control can achieve the desired multi-AUV formation within a fixed settling time in any initial system state. Secondly, an event-triggered communication strategy is developed to govern the communication among AUVs, and the communication energy consumption can be decremented. The time-varying formation obstacle avoidance control algorithm based on IAPF-LF is designed to avoid static and dynamic obstacles, the desired formation is maintained in the presence of external disturbances, and there is no Zeno behavior under the fixed-time event-triggered consensus control strategy.The stability of the system is proved by the Lyapunov function and inequality scaling. Finally, simulation examples and water pool experiments are reported to verify the performance of the proposed theoretical algorithms.

关键词： Autonomous underwater vehicle(AUV) event-triggered control fixed-time consensus formation obstacle avoidance improved artificial potential field and leader-follower strategy(IAPF-LF)

Calculation Methods of Added Resistance and Ship Motion Response Based on Potential Flow and Viscous Flow Theory

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2022年第3期36卷 488-499页

作者： WU Qi-ming ZHANG Bao-ji Shanghai Maritime University College of Ocean Science and EngineeringShanghai 201306China

To improve the energy efficiency of ships and to predict ship motion response under actual sea conditions,the far-field theory,strip theory,and Fujii and Takahashi’s modified semi-empirical method are based and studied to calculate the wave-induced added resistance.Firstly,a new modified formula based on the Maruo method is presented to calculate the radiation added resistance for the ship with a complex surface.Meanwhile,some calculation details such as the Green function,the shape of the sections(shape below the still water level or shape below the wave level)in the strip theory,and so on are discussed.Finally,the CFD method is used to simulate the motions of the hull and the added resistance,and the results of the CFD method and those of other numerical methods are analyzed and compared with the experiment results.The modified method in the paper can predict the added resistance in waves for the complex-hull-surface ships well and quickly.

关键词： wave-induced added resistance strip theory computation fluid dynamics motion response

Novel Energy-Efficient Opportunistic Routing Protocol for Marine Wireless Sensor Networks Based on Compressed Sensing and Power Control

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean university of China 2022年第6期21卷 1504-1516页

作者： XIAN Jiangfeng WU Huafeng MEI Xiaojun ZHANG Yuanyuan CHEN Xinqiang ZHANG Qiannan LIANG Linian Institute of Logistics Science and Engineering Shanghai Maritime UniversityShanghai 201306China Merchant Marine College Shanghai Maritime UniversityShanghai 201306China College of Information Engineering Shanghai Maritime UniversityShanghai 201306China Institute of Atmospheric Sciences&Department of Atmospheric and Oceanic Sciences Fudan UniversityShanghai 200438China

In marine wireless sensor networks(MWSNs),an appropriate routing protocol is the key to the collaborative collection and efficient transmission of massive data.However,designing an appropriate routing protocol under the condition of sparse marine node deployment,highly dynamic network topology,and limited node energy is complicated.Moreover,the absence of continuous endto-end connection introduces further difficulties in the design of routing protocols.In this case,we present a novel energy-efficient opportunistic routing(Novel Energy-Efficient Opportunistic Routing,NEOR)protocol for MWSNs that is based on compressed sensing and power control.First,a lightweight time-series prediction method-weighted moving average method is proposed to predict the packet advancement value such that the number of location information that is exchanged among a node and its neighbor nodes can be minimized.Second,an adaptive power control mechanism is presented to determine the optimal transmitting power and candidate nodeset on the basis of node mobility,packet advancement,communication link quality,and remaining node energy.Subsequently,a timer-based scheduling algorithm is utilized to coordinate packet forwarding to avoid packet conflict.Furthermore,we introduce the compressed sensing theory to compress perceptual data at source nodes and reconstruct the original data at sink nodes.Therefore,energy consumption in the MWSNs is greatly reduced due to the decrease in the amount of data perception and transmission.Numerical simulation experiments are carried out in a wide range of marine scenarios to verify the superiority of our approach over selected benchmark algorithms.

关键词： marine wireless sensor networks opportunistic routing weighted moving average adaptive power control compressed sensing