检索结果-南通市图书馆

Stabilization of Fractional Order Hyperchaotic Systems with Uncertainties via Output Feedback Sliding Mode Control

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2015年第1期22卷 23-29页

作者： liwei deng Shenmin Song Center for Control Theory and Guidance Technology Harbin Institute of Technology School of Automation Harbin University of Science and Technology

An output feedback sliding mode controller is designed for the stabilization of fractional order hyperchaotic systems including uncertainties in the state matrix and the output matrix. On the basis of auxiliary system,a sliding mode control law with output feedback characteristics is researched by studying the structure decomposition of fractional order hyperchaotic systems. Based on fractional order Lyapunov stability theorem,a switching surface is designed by using linear matrix inequality( LMI) method. Using a simple adaptation,an improved sliding mode controller is given to guarantee the existence of the sliding mode. Moreover,numerical simulations are performed to confirm the effectiveness and feasibility of the stabilization control scheme.

关键词： output feedback sliding mode hyperchaotic fraction

A Fine-Grained Object Detection Model for Aerial Images Based on YOLOv5 Deep Neural Network

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2023年第1期32卷 51-63页

作者： ZHANG Rui XIE Cong deng liwei Heilongjiang Provincial Key Laboratory of Complex Intelligent System and Integration School of AutomationHarbin University of Science and Technology

Many advanced object detection algorithms are mainly based on natural scenes object and rarely dedicated to fine-grained objects. This seriously limits the application of these advanced detection algorithms in remote sensing object detection. How to apply horizontal detection in remote sensing images has important research significance. The mainstream remote sensing object detection algorithms achieve this task by angle regression, but the periodicity of angle leads to very large losses in this regression method, which increases the difficulty of model learning. Circular smooth label(CSL)solved this problem well by transforming the regression of angle into a classification form. YOLOv5 combines many excellent modules and methods in recent years, which greatly improves the detection accuracy of small *** use YOLOv5 as a baseline and combine the CSL method to learn the angle of arbitrarily oriented targets,and distinguish the fine-grained between instance classes by adding an attention mechanism module to accomplish the fine-grained target detection task for remote sensing images. Our improved model achieves an average category accuracy of 39.2% on the FAIR1M dataset. Although our method does not achieve satisfactory results,this approach is very efficient and simple, reducing the hardware requirements of the model.

关键词： Deep learning Neural networks Object detection Transformers Hardware Classification algorithms Task analysis

A Novel Unsupervised MRI Synthetic CT Image Generation Framework with Registration Network

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第11期77卷 2271-2287页

作者： liwei deng Henan Sun Jing Wang Sijuan Huang Xin Yang Heilongjiang Provincial Key Laboratory of Complex Intelligent System and Integration School of AutomationHarbin University of Science and TechnologyHarbin150080China Institute for Brain Research and Rehabilitation South China Normal UniversityGuangzhou510631China Department of Radiation Oncology Sun Yat-sen University Cancer CenterState Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineGuangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and TherapyGuangzhou510060China

In recent years,radiotherapy based only on Magnetic Resonance(MR)images has become a hot spot for radiotherapy planning research in the current medical ***,functional computed tomography(CT)is still needed for dose calculation in the *** deep-learning approaches to synthesized CT images from MR images have raised much research interest,making radiotherapy based only on MR images *** this paper,we proposed a novel unsupervised image synthesis framework with registration *** paper aims to enforce the constraints between the reconstructed image and the input image by registering the reconstructed image with the input image and registering the cycle-consistent image with the input ***,this paper added ConvNeXt blocks to the network and used large kernel convolutional layers to improve the network’s ability to extract *** research used the collected head and neck data of 180 patients with nasopharyngeal carcinoma to experiment and evaluate the training model with four evaluation *** the same time,this research made a quantitative comparison of several commonly used model *** evaluate the model performance in four evaluation metrics which achieve Mean Absolute Error(MAE),Root Mean Square Error(RMSE),Peak Signal-to-Noise Ratio(PSNR),and Structural Similarity(SSIM)are 18.55±1.44,86.91±4.31,33.45±0.74 and 0.960±0.005,*** with other methods,MAE decreased by 2.17,RMSE decreased by 7.82,PSNR increased by 0.76,and SSIM increased by *** results show that the model proposed in this paper outperforms other methods in the quality of image *** work in this paper is of guiding significance to the study of MR-only radiotherapy planning.

关键词： MRI-CT image synthesis variational auto-encoder medical image translation MRI-only based radiotherapy

Meta-Learning Multi-Scale Radiology Medical Image Super-Resolution

维普期刊数据库评论

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5期75卷 2671-2684页

作者： liwei deng Yuanzhi Zhang Xin Yang Sijuan Huang Jing Wang Heilongjiang Provincial Key Laboratory of Complex Intelligent System and Integration School of AutomationHarbin University of Science and TechnologyHarbin150080HeilongjiangChina Department of Radiation Oncology Sun Yat-sen University Cancer CenterState Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineGuangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and TherapyGuangzhou510060GuangdongChina Faculty of Rehabilitation Medicine Biofeedback LaboratoryGuangzhou Xinhua UniversityGuangzhou510520GuangdongChina

High-resolution medical images have important medical value,but are difficult to obtain *** by hardware equipment and patient’s physical condition,the resolution of directly acquired medical images is often not ***,many researchers have thought of using super-resolution algorithms for secondary processing to obtain high-resolution medical ***,current super-resolution algorithms only work on a single scale,and multiple networks need to be trained when super-resolution images of different scales are *** definitely raises the cost of acquiring high-resolution medical ***,we propose a multi-scale superresolution algorithm using *** algorithm combines a metalearning approach with an enhanced depth of residual super-resolution network to design a meta-upscale *** meta-upscale module utilizes the weight prediction property of meta-learning and is able to perform the super-resolution task of medical images at any ***,we design a non-integer mapping relation for super-resolution,which allows the network to be trained under non-integer magnification *** to the state-of-the-art single-image super-resolution algorithm on computed tomography images of the pelvic *** meta-learning multiscale superresolution algorithm obtained a surpassing of about 2%at a smaller model *** on different parts proves the high generalizability of our ***-scale super-resolution algorithms using meta-learning can compensate for hardware device defects and reduce secondary harm to patients while obtaining high-resolution medical *** can be of great use in imaging related fields.

关键词： Super resolution deep learning meta learning computed tomography

Chaotic Synchronization Control based on Finite-time Sliding Model Controller 36

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chaotic Synchronization Control based on Finite-time Sliding...

Equation of state of CAS phase to pressure of the uppermost lower mantle at ambient temperature

第36届中国控制会议

作者： Gao Jun-shan Lan-lan Shi deng liwei Wu Bo Academy of Automation Harbin university of science and technology

ISBN: (纸本)9781538629185

For the problem of the synchronization between two chaotic systems with external disturbances and nonlinear input,based on the Lyapunov’s stability theory and combined the finite time principle with control technology existed,a sliding mode controller was designed by a new type of sliding surface and the corresponding control rule of sliding mode selectivity to achieve the synchronization control of two chaotic systems and make the system reach and maintain the balance state in a limited ***,take Lorenz system and Liu system for example,some MATLAB simulation results verify the feasibility and effectiveness of the sliding mode controller design.

关键词： nonlinear control sliding mode controller finite-time control Lyapunov’s stability theory

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Science China Earth Sciences 2011年第9期54卷 1394-1399页

作者： LIU Xi HE Qiang deng liwei ZHAI ShuangMeng HU XiaoMin LI BaoSheng ZHANG LiFei CHEN ZhiQiang LIU Qiong Key Laboratory of Orogenic Belts and Crustal Evolution MOE School of Earth and Space Sciences Peking University Beijing 100871 China Geophysical Laboratory and Center for High-pressure Research Carnegie Institution of Washington 5251 Broad Branch Road NW Washington DC 20015-1305 USA Mineral Physics Institute State University of New York Stony Brook New York 11794 USA National Synchrotron Light Source Brookhaven National Laboratory Upton New York 11973 USA

The CAS phase is a major constituent phase for the continental crust and basaltic compositions at the P-T conditions of the Earth＇s mantle, and potentially plays an important role in the geodynamic processes related to slab subduction. Its equation of state has been investigated here at ambient temperature up to about 25 GPa by using a diamond-anvil cell and synchrotron Xray radiation. Its P-V data, fitted to the third-order Birch-Murnaghan equation, yield an isothermal bulk modulus （KT） of 185 （9） GPa and first pressure derivative （ KT^t ） of 7.2 （12）. If KT^t is fixed at 4, file derived Kr is 212 （4） GPa. Additionally, the CAS phase is strongly elastically anisotropic, with its a-axis direction much less compressible than c-axis direction： Kr-a ： Kr-c = 2.19.

关键词： anisotropic elasticity CAS phase equation of state synchrotron X-ray radiation

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

在线全文

学校读者我要写书评

暂无评论

Instrumentation 2016年第1期3卷 21-29页

作者： GAO Junshan deng liwei SONG Shenmin School of Automation Harbin University of Science and Technology Center for Control Theory and Guidance Technology Harbin Institute of Technology

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and external disturbances. The controller is based on the fractional calculus and nonsingular terminal sliding mode control technique,and it guarantees the convergence of attitude tracking error in finite time rather than in the asymptotic sense. With respect to the controller,a fractional order sliding surface is given,the corresponding control scheme is proposed based on Lyapunov stability theory to guarantee the sliding condition,and the finite time stability of the whole close loop system is also proven. Finally,numerical simulations are presented to illustrate the performance of the proposed scheme.

关键词： flexible spacecraft attitude tracking fractional calculus sliding mode control finite time control

基于分数阶滑模的挠性航天器姿态鲁棒跟踪控制

在线全文

学校读者我要写书评

暂无评论

航空学报 2013年第8期34卷 1915-1923页

作者：邓立为宋申民哈尔滨工业大学控制理论与制导技术研究中心黑龙江哈尔滨150001

针对挠性航天器姿态跟踪控制问题,提出一种新型的具有强鲁棒性的分数阶滑模控制器。利用分数阶微分算子的快速收敛性与信息记忆性,在滑模面与控制输入中均引入分数阶微分算子,使新型控制器具有分数阶微分与滑模控制的双重优点,从而使姿... 详细信息

针对挠性航天器姿态跟踪控制问题,提出一种新型的具有强鲁棒性的分数阶滑模控制器。利用分数阶微分算子的快速收敛性与信息记忆性,在滑模面与控制输入中均引入分数阶微分算子,使新型控制器具有分数阶微分与滑模控制的双重优点,从而使姿态跟踪控制系统具有更好的快速性、强鲁棒性和良好的抗干扰性。进一步使用Lyapunov理论与分数阶稳定性理论证明了整个系统的稳定性,分析了分数阶滑模面的优点。数值仿真验证了分数阶滑模控制器的有效性与良好的控制性能。

关键词：挠性航天器分数阶滑模分数阶微积分强鲁棒性姿态跟踪

在线全文

学校读者我要写书评

暂无评论

聚甲醛生产中的挥发分脱除

合成树脂及塑料 2017年第1期34卷 52-56页

作者：邓立伟唐山中浩化工有限公司河北省唐山市063611

根据聚甲醛的生产特点,通过研究双螺杆挤出机的脱除挥发分(简称脱挥)机理,结合聚甲醛实际生产的脱挥工艺,从螺杆组合、螺杆转速、进料量、筒体温度、螺杆长径比等方面分析了影响挤出机脱挥效率的主要因素,给出了适合聚甲醛生产的工艺参... 详细信息

根据聚甲醛的生产特点,通过研究双螺杆挤出机的脱除挥发分(简称脱挥)机理,结合聚甲醛实际生产的脱挥工艺,从螺杆组合、螺杆转速、进料量、筒体温度、螺杆长径比等方面分析了影响挤出机脱挥效率的主要因素,给出了适合聚甲醛生产的工艺参数:进料量与螺杆转速的比值维持在18~20,筒体温度为180~195℃,真空度维持在0.01 MPa以下。通过对现有挤出机脱挥系统的优化改造,使脱挥后聚甲醛中甲醛挥发量达100μg/g以下。

关键词：聚甲醛脱挥双螺杆挤出机