检索结果-南通市图书馆

Ordered Bicontinuous Network Structures Regulated by Orientational Interactions in a Rod-Coil Block Copolymer

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第5期42卷 636-642,I0008页

作者： xiao-Lin Lyu Shi-Chu Yang An-Qi xiao Ping-Ping Hou Wei zhang Hong-bing Pan Zhi-Hao Shen Xing-He Fan Qi-Feng Zhou Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China Key Laboratory of Advanced Materials Technologies International(HongKong Macao and Taiwan)Joint Laboratory on Advanced Materials TechnologiesCollege of Materials Science and EngineeringFuzhou UniversityFuzhou350108China

The rich phase behavior of block copolymers(BCPs)has drawn great attention in recent ***,the double diamond(DD)phase is rarely obtained because of the competition between the minimization of interfacial energy and packing ***,a rod-coil BCP containing mesogen-jacketed liquid crystalline polymer is designed to acquire ordered bicontinuous network *** reduction of internal energy originating from the orientational interaction among the rod blocks can compensate for the free energy penalty of packing frustration to stabilize the DD *** resulting BCP can also experience lamellae-to-DD and double gyroid-to-lamellae transitions by changing the annealing *** results make the rod-coil BCP an excellent candidate for the self-assembly of ordered network structures,demonstrating great potential in nanopatterning and metamaterials.

关键词： Block copolymer Rod-coil Ordered bicontinuous phase Double diamond Double gyroid

高阶近似黎曼解模型在火炮内弹道两相流中的应用研究

在线全文

学校读者我要写书评

暂无评论

兵工学报 2011年第10期32卷 1200-1205页

作者：程诚张小兵南京理工大学能源与动力工程学院江苏南京210094

为了提高对内弹道两相流过程中复杂激波系的捕捉能力,将基于Roe型格式的近似黎曼解模型推广到火炮两相流数值模拟中,通过TVD性质高阶修正以及显式时间步分裂4阶Runge-Kutta法,构造了气体—固体两相流高阶黎曼近似格式,并保证了气体—固... 详细信息

为了提高对内弹道两相流过程中复杂激波系的捕捉能力,将基于Roe型格式的近似黎曼解模型推广到火炮两相流数值模拟中,通过TVD性质高阶修正以及显式时间步分裂4阶Runge-Kutta法,构造了气体—固体两相流高阶黎曼近似格式,并保证了气体—固体两相格式的一致性。通过与激波管、源项验证等具有解析解的经典算例进行对比,验证了所构造高阶方法的准确性与稳定性。点火管数值验证结果准确形象地模拟了点火管内复杂两相流动过程,分析了不同因素对于点火性能的影响,并与实验结果进行对比分析,说明了基于Roe格式的高阶近似黎曼解模型在处理火炮膛内强间断及复杂波系时有较强的分辨能力。

关键词：流体力学近似黎曼解内弹道两相流点火管

基于FLUENT软件和内弹道模型双向耦合的超高射频火炮发射过程模拟

在线全文

学校读者我要写书评

暂无评论

兵工学报 2016年第10期37卷 1949-1955页

作者：罗乔张小兵南京理工大学能源与动力工程学院江苏南京210094

弹头阻力计算的准确性直接决定了超高射频火炮内弹道数值模拟的准确性。为了提高超高射频火炮内弹道过程数值模拟的准确性,利用二次开发工具UDF将FLUENT软件和经典内弹道(CIB)模型双向耦合计算超高射频火炮弹前流场,得到了超高射频火炮... 详细信息

弹头阻力计算的准确性直接决定了超高射频火炮内弹道数值模拟的准确性。为了提高超高射频火炮内弹道过程数值模拟的准确性,利用二次开发工具UDF将FLUENT软件和经典内弹道(CIB)模型双向耦合计算超高射频火炮弹前流场,得到了超高射频火炮发射过程中第2发弹丸的弹头阻力,分析了不同射击频率下弹头阻力的变化规律。结果表明:FLUENT-CIB模型双向耦合计算能够得到弹前身管内火药气体各个时刻的流场分布,提高了弹头阻力计算的准确性;弹头阻力在弹丸启动后很快由减小变成增大,增大到某个极大值后又逐渐减小,直到弹丸出炮口,这个变化规律在不同射击频率下普遍存在;射频降低,在弹丸运动前期弹头阻力增幅减小,在弹丸运动后期弹头阻力降幅也减小。

关键词：兵器科学与技术内弹道超高射频火炮数值模拟 FLUENT 双向耦合

某制导炮弹二维两相流内弹道性能分析与数值模拟研究

在线全文

学校读者我要写书评

暂无评论

兵工学报 2015年第1期36卷 58-63页

作者：程诚张小兵南京理工大学能源与动力工程学院江苏南京210094

为了研究某制导炮弹二维两相流内弹道性能,简化两相流多维数值模拟中弹底运动边界处理的复杂性,提高运动边界处的计算精度,建立了基于任意拉格朗日欧拉方法的某制导炮弹内弹道二维气-固两相流模型,空间上采用具有TVD特性的高阶MUSCL类... 详细信息

为了研究某制导炮弹二维两相流内弹道性能,简化两相流多维数值模拟中弹底运动边界处理的复杂性,提高运动边界处的计算精度,建立了基于任意拉格朗日欧拉方法的某制导炮弹内弹道二维气-固两相流模型,空间上采用具有TVD特性的高阶MUSCL类型的有限体积法对方程进行离散,时间方向采用4阶Runge-Kutta方法进行时间推进。通过拥有解析解的数值验证算例,验证了数值格式以及动网格生成方法的准确性。对某大口径制导炮弹内弹道膛内循环过程进行二维两相流数值仿真。模拟结果准确地反映了整个内弹道循环膛内两相流动特性及其发展过程,并与实验结果有较好的一致性。同时分析了不同点火因素对该制导炮弹内弹道性能的影响,为后续深入优化该制导炮弹内弹道性能及发射安全性提供了理论基础。

关键词：兵器科学与技术内弹道两相流数值模拟制导炮弹

Classification of knowledge graph completeness measurement techniques

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2024年第1期35卷 154-162页

作者： zhang Ying xiao Gang Institute of Systems Engineering Academy of Military SciencesBeijing 100107China

At present,although knowledge graphs have been widely used in various fields such as recommendation systems,question and answer systems,and intelligent search,there are always quality problems such as knowledge omissions and *** assessment and control,as an important means to ensure the quality of knowledge,can make the applications based on knowledge graphs more complete and more accurate by reasonably assessing the knowledge graphs and fixing and improving the quality problems at the same ***,as an indispensable part of the knowledge graph construction process,the results of quality assessment and control determine the usefulness of the knowledge *** them,the assessment and enhancement of completeness,as an important part of the assessment and control phase,determine whether the knowledge graph can fully reflect objective phenomena and reveal potential connections among *** this paper,we review specific techniques of completeness assessment and classify completeness assessment techniques in terms of closed world assumptions,open world assumptions,and partial completeness *** purpose of this paper is to further promote the development of knowledge graph quality control and to lay the foundation for subsequent research on the completeness assessment of knowledge graphs by reviewing and classifying completeness assessment techniques.

关键词： quality assessment completeness assessment closed world assumptions open world assumption partial completeness assumption

For Mega-Constellations: Edge Computing and Safety Management Based on Blockchain Technology

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第2期21卷 59-73页

作者： Zhen zhang bing Guo Chengjie Li College of Computer Science Sichuan UniversityChengdu 610064China The Key Laboratory for Computer Systems of State Ethnic Affairs Commission School of Computer Science and TechnologySouthwest Minzu UniversityChengdu 610225China National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of ChinaChengdu 611731China

In mega-constellation Communication Systems, efficient routing algorithms and data transmission technologies are employed to ensure fast and reliable data transfer. However, the limited computational resources of satellites necessitate the use of edge computing to enhance secure *** edge computing reduces the burden on cloud computing, it introduces security and reliability challenges in open satellite communication channels. To address these challenges, we propose a blockchain architecture specifically designed for edge computing in mega-constellation communication systems. This architecture narrows down the consensus scope of the blockchain to meet the requirements of edge computing while ensuring comprehensive log storage across the network. Additionally, we introduce a reputation management mechanism for nodes within the blockchain, evaluating their trustworthiness, workload, and efficiency. Nodes with higher reputation scores are selected to participate in tasks and are appropriately incentivized. Simulation results demonstrate that our approach achieves a task result reliability of 95% while improving computational speed.

关键词： blockchain consensus mechanism edge computing mega-constellation reputation management

Multimodal fusion recognition for digital twin

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2024年第2期10卷 337-346页

作者： Tianzhe Zhou Xuguang zhang bing Kang Mingkai Chen Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Ministry of EducationNanjing University of Posts and TelecommunicationsNanjing210003China

The digital twin is the concept of transcending reality,which is the reverse feedback from the real physical space to the virtual digital *** hold great prospects for this emerging *** order to realize the upgrading of the digital twin industrial chain,it is urgent to introduce more modalities,such as vision,haptics,hearing and smell,into the virtual digital space,which assists physical entities and virtual objects in creating a closer ***,perceptual understanding and object recognition have become an urgent hot topic in the digital *** surface material classification schemes often achieve recognition through machine learning or deep learning in a single modality,ignoring the complementarity between multiple *** order to overcome this dilemma,we propose a multimodal fusion network in our article that combines two modalities,visual and haptic,for surface material *** the one hand,the network makes full use of the potential correlations between multiple modalities to deeply mine the modal semantics and complete the data *** the other hand,the network is extensible and can be used as a universal architecture to include more *** show that the constructed multimodal fusion network can achieve 99.42%classification accuracy while reducing complexity.

关键词： Digital twin Multimodal fusion Object recognition Deep learning Transfer learning

An Online Q-Learning Method for Linear-Quadratic Nonzero-Sum Stochastic Differential Games with Completely Unknown Dynamics

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

Journal of Systems Science & Complexity 2024年第5期37卷 1907-1922页

作者： zhang Bao-Qiang WANG bing-Chang CAO Ying School of Control Science and Engineering Shandong University

In this paper, the authors design a reinforcement learning algorithm to solve the adaptive linear-quadratic stochastic n-players non-zero sum differential game with completely unknown dynamics. For each player, a critic network is used to estimate the Q-function, and an actor network is used to estimate the control input. A model-free online Q-learning algorithm is obtained for solving this kind of problems. It is proved that under some mild conditions the system state and weight estimation errors can be uniformly ultimately bounded. A simulation with five players is given to verify the effectiveness of the algorithm.

关键词： Actor-critic algorithm model-free adaptive control nonzero-sum stochastic game reinforcement learning

Preoperative prediction of perineural invasion of rectal cancer based on a magnetic resonance imaging radiomics model:A dual-center study

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2024年第16期30卷 2233-2248页

作者： Yan Liu Bai-Jin-Tao Sun Chuan zhang bing Li xiao-Xuan Yu Yong Du Department of Radiology The Affiliated Hospital of North Sichuan Medical CollegeNanchong 637000Sichuan ProvinceChina Department of Radiology The Affiliated Hospital of North Sichuan Medical CollegeNanchong 637000Sichuan ProvinceChina.duyong@***

BACKGROUND Perineural invasion(PNI)has been used as an important pathological indicator and independent prognostic factor for patients with rectal cancer(RC).Preoperative prediction of PNI status is helpful for individualized treatment of ***,several radiomics studies have been used to predict the PNI status in RC,demonstrating a good predictive effect,but the results lacked *** preoperative prediction of PNI status is still challenging and needs further *** To establish and validate an optimal radiomics model for predicting PNI status preoperatively in RC *** This retrospective study enrolled 244 postoperative patients with pathologically confirmed RC from two independent *** patients underwent preoperative high-resolution magnetic resonance imaging(MRI)between May 2019 and August *** radiomics features were extracted and selected from oblique axial T2-weighted imaging(T2WI)and contrast-enhanced T1WI(T1CE)*** radiomics signatures were constructed using logistic regression analysis and the predictive potential of various sequences was compared(T2WI,T1CE and T2WI+T1CE fusion sequences).A clinical-radiomics(CR)model was established by combining the radiomics features and clinical risk *** internal and external validation groups were used to validate the proposed *** area under the receiver operating characteristic curve(AUC),DeLong test,net reclassification improvement(NRI),integrated discrimination improvement(IDI),calibration curve,and decision curve analysis(DCA)were used to evaluate the model *** Among the radiomics models,the T2WI+T1CE fusion sequences model showed the best predictive performance,in the training and internal validation groups,the AUCs of the fusion sequence model were 0.839[95%confidence interval(CI):0.757-0.921]and 0.787(95%CI:0.650-0.923),which were higher than those of the T2WI and T1CE sequence *** CR model constructed by combinin

关键词： Rectal cancer Perineural invasion Magnetic resonance imaging Radiomics Nomogram