期刊文献+
共找到73篇文章
< 1 2 4 >
每页显示 20 50 100
Autonomous relative optical navigation based on unified modeling of external systematic errors
1
作者 Dayi WANG Bowen SUN +2 位作者 Maodeng LI Jiaxing LI Haiyin ZHOU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第3期282-289,共8页
To solve the problem that external systematic errors of the optical camera cannot be fully estimated due to limited computing resources,a unified dimensionality reduction representation method for the external systema... To solve the problem that external systematic errors of the optical camera cannot be fully estimated due to limited computing resources,a unified dimensionality reduction representation method for the external systematic errors of the optical camera is proposed,and autonomous relative optical navigation is realized.The camera translational and misalignment errors are converted into a three-dimensional rotation error,whose differential model can be established through specific attitude control and appropriate assumption.Then,the rotation error and the relative motion state are jointly estimated in an augmented Kalman filter framework.Compared with the traditional method that estimates the camera translational and misalignment errors,the proposed method reduces the computational complexity in that the estimated state dimension is reduced.Furthermore,as demonstrated by numerical simulation,the estimation accuracy is improved significantly. 展开更多
关键词 unified model Systematic errors Optical navigation Observability analysis CALIBRATION
原文传递
An automatic unified modeling method of geological object and engineering object based on tri-prism(TP) 被引量:1
2
作者 张荣春 李浩 +1 位作者 吴铭飞 王亚芹 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第4期1419-1426,共8页
For the interaction relation between geological object and engineering object in some fields related to water conservancy and hydropower, a unified modeling idea was proposed. On the basis of summarizing both advantag... For the interaction relation between geological object and engineering object in some fields related to water conservancy and hydropower, a unified modeling idea was proposed. On the basis of summarizing both advantages and disadvantages of existing modeling methods, an automatic unified modeling method of both engineering and geological objects based on tri-prism(TP) model was presented. Through the lossless correction algorithm of deviated drill holes contained in this method, the real deviated drill holes could be corrected into the equivalent virtual vertical ones. And the correction accuracy fully meets the requirements of unified modeling. With the virtual vertical drilling data, TIN construction of both cover layer and other stratums would be built in order to obtain the 3D geological model. Then, the engineering design data would be introduced into the 3D geological model for achieving unified modeling. For this process, the volume subdividing and restructuring principles were introduced to deal with the spatial relationships between engineering object and geological object. In order to improve the efficiency of unified modeling, the reconstruction of TIN based on constraint information was also applied in this method. At last, the feasibility and validation of the unified modeling method as well as its relevant key algorithms were verified by specific experiments and analysis of results. 展开更多
关键词 tri-prism(TP) model unified modeling deviated drill holes correction volume subdividing constraint information
在线阅读 下载PDF
Foundations of Programmable Process Structures for the unified modeling and simulation of agricultural and aquacultural systems
3
作者 Monika Varga Bela Csukas 《Information Processing in Agriculture》 EI CSCD 2024年第1期91-108,共18页
This research paper defines the theoretical foundations and computational implementation of a non-conventional modeling and simulation methodology,inspired by the needs of problem solving for biological,agricultural,a... This research paper defines the theoretical foundations and computational implementation of a non-conventional modeling and simulation methodology,inspired by the needs of problem solving for biological,agricultural,aquacultural and environmental systems.The challenging practical problem is to develop a framework for automatic generation of causally right and balance-based,unified models that can also be applied for the effective coupling amongst the various(sophisticated field-specific,sensor data processing-based,upper level optimization-driven,etc.)models.The scientific problem addressed in this innovation is to develop Programmable Process Structures(PPS)by combining functional basis of systems theory,structural approach of net theory and computational principles of agent based modeling.PPS offers a novel framework for the automatic generation of easily extensible and connectible,unified models for the underlying complex systems.PPS models can be generated from one state and one transition meta-prototypes and from the transition oriented description of process structure.The models consist of unified state and transition elements.The local program containing prototype elements,derived also from the meta-prototypes,are responsible for the case-specific calculations.The integrity and consistency of PPS architecture are based on the meta-prototypes,prepared to distinguish between the conservation-laws-based measures and the signals.The simulation is based on data flows amongst the state and transition elements,as well as on the unification based data transfer between these elements and their calculating prototypes.This architecture and its AI language-based(Prolog)implementation support the integration of various field-and task-specific models,conveniently.The better understanding is helped by a simple example.The capabilities of the recently consolidated general methodology are discussed on the basis of some preliminary applications,focusing on the recently studied agricultural and aquacultural cases. 展开更多
关键词 unified process model Meta-prototype-based architecture Transition-based structure representation Locally programmable functionality prototypes Agricultural systems Aquacultural systems
原文传递
Design of a Private Cloud Platform for Distributed Logging Big Data Based on a Unified Learning Model of Physics and Data
4
作者 Cheng Xi Fu Haicheng Tursyngazy Mahabbat 《Applied Geophysics》 2025年第2期499-510,560,共13页
Well logging technology has accumulated a large amount of historical data through four generations of technological development,which forms the basis of well logging big data and digital assets.However,the value of th... Well logging technology has accumulated a large amount of historical data through four generations of technological development,which forms the basis of well logging big data and digital assets.However,the value of these data has not been well stored,managed and mined.With the development of cloud computing technology,it provides a rare development opportunity for logging big data private cloud.The traditional petrophysical evaluation and interpretation model has encountered great challenges in the face of new evaluation objects.The solution research of logging big data distributed storage,processing and learning functions integrated in logging big data private cloud has not been carried out yet.To establish a distributed logging big-data private cloud platform centered on a unifi ed learning model,which achieves the distributed storage and processing of logging big data and facilitates the learning of novel knowledge patterns via the unifi ed logging learning model integrating physical simulation and data models in a large-scale functional space,thus resolving the geo-engineering evaluation problem of geothermal fi elds.Based on the research idea of“logging big data cloud platform-unifi ed logging learning model-large function space-knowledge learning&discovery-application”,the theoretical foundation of unified learning model,cloud platform architecture,data storage and learning algorithm,arithmetic power allocation and platform monitoring,platform stability,data security,etc.have been carried on analysis.The designed logging big data cloud platform realizes parallel distributed storage and processing of data and learning algorithms.The feasibility of constructing a well logging big data cloud platform based on a unifi ed learning model of physics and data is analyzed in terms of the structure,ecology,management and security of the cloud platform.The case study shows that the logging big data cloud platform has obvious technical advantages over traditional logging evaluation methods in terms of knowledge discovery method,data software and results sharing,accuracy,speed and complexity. 展开更多
关键词 unified logging learning model logging big data private cloud machine learning
在线阅读 下载PDF
A framework for an integrated unified modeling language 被引量:3
5
作者 Mohammad ALSHAYEB Nasser KHASHAN Sajjad MAHMOOD 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2016年第2期143-159,共17页
The unified modeling language(UML) is one of the most commonly used modeling languages in the software industry.It simplifies the complex process of design by providing a set of graphical notations,which helps express... The unified modeling language(UML) is one of the most commonly used modeling languages in the software industry.It simplifies the complex process of design by providing a set of graphical notations,which helps express the objectoriented analysis and design of software projects.Although UML is applicable to different types of systems,domains,methods,and processes,it cannot express certain problem domain needs.Therefore,many extensions to UML have been proposed.In this paper,we propose a framework for integrating the UML extensions and then use the framework to propose an integrated unified modeling language-graphical(iUML-g) form.iUML-g integrates the existing UML extensions into one integrated form.This includes an integrated diagram for UML class,sequence,and use case diagrams.The proposed approach is evaluated using a case study.The proposed iUML-g is capable of modeling systems that use different domains. 展开更多
关键词 unified modeling language (UML) INTEGRATION modeling System analysis and design
原文传递
Validation of static properties in unified modeling language models for cyber physical systems 被引量:2
6
作者 Gabriela MAGUREANU Madalin GAVRILESCU Dan PESCARU 《Journal of Zhejiang University-Science C(Computers and Electronics)》 SCIE EI 2013年第5期332-346,共15页
Cyber physical systems (CPSs) can be found nowadays in various fields of activity. The increased interest for these systems as evidenced by the large number of applications led to complex research regarding the most s... Cyber physical systems (CPSs) can be found nowadays in various fields of activity. The increased interest for these systems as evidenced by the large number of applications led to complex research regarding the most suitable methods for design and development. A promising solution for specification, visualization, and documentation of CPSs uses the Object Management Group (OMG) unified modeling language (UML). UML models allow an intuitive approach for embedded systems design, helping end-users to specify the requirements. However, the UML models are represented in an informal language. Therefore, it is difficult to verify the correctness and completeness of a system design. The object constraint language (OCL) was defined to add constraints to UML, but it is deficient in strict notations of mathematics and logic that permits rigorous analysis and reasoning about the specifications. In this paper, we investigated how CPS applications modeled using UML deployment diagrams could be formally expressed and verified. We used Z language constructs and prototype verification system (PVS) as formal verification tools. Considering some relevant case studies presented in the literature, we investigated the opportunity of using this approach for validation of static properties in CPS UML models. 展开更多
关键词 Cyber physical system (CPS) unified modeling language (UML) design Formal verification Prototype verification system (PVS) Z language
原文传递
Unified deep learning model for predicting fundus fluorescein angiography image from fundus structure image 被引量:7
7
作者 Yiwei Chen Yi He +3 位作者 Hong Ye Lina Xing Xin Zhang Guohua Shi 《Journal of Innovative Optical Health Sciences》 SCIE EI CSCD 2024年第3期105-113,共9页
The prediction of fundus fluorescein angiography(FFA)images from fundus structural images is a cutting-edge research topic in ophthalmological image processing.Prediction comprises estimating FFA from fundus camera im... The prediction of fundus fluorescein angiography(FFA)images from fundus structural images is a cutting-edge research topic in ophthalmological image processing.Prediction comprises estimating FFA from fundus camera imaging,single-phase FFA from scanning laser ophthalmoscopy(SLO),and three-phase FFA also from SLO.Although many deep learning models are available,a single model can only perform one or two of these prediction tasks.To accomplish three prediction tasks using a unified method,we propose a unified deep learning model for predicting FFA images from fundus structure images using a supervised generative adversarial network.The three prediction tasks are processed as follows:data preparation,network training under FFA supervision,and FFA image prediction from fundus structure images on a test set.By comparing the FFA images predicted by our model,pix2pix,and CycleGAN,we demonstrate the remarkable progress achieved by our proposal.The high performance of our model is validated in terms of the peak signal-to-noise ratio,structural similarity index,and mean squared error. 展开更多
关键词 Fundus fluorescein angiography image fundus structure image image translation unified deep learning model generative adversarial networks
原文传递
Micro-macro Unified Analysis of Flow Behavior of Particle-reinforced Metal Matrix Composites 被引量:2
8
作者 张鹏 李付国 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2010年第2期252-259,共8页
This article presents a micro-macro unified model for predicting the deformation of metal matrix composites (MMCs). A macro-scale model is developed to obtain the proper boundary conditions for the micro-scale model... This article presents a micro-macro unified model for predicting the deformation of metal matrix composites (MMCs). A macro-scale model is developed to obtain the proper boundary conditions for the micro-scale model, which is used to assess the microstructural deformation of materials. The usage of the submodel technique in the analysis makes it possible to shed light on the stress and strain field at the microlevel. This is helpful to investigate the linkage between the microscopic and the macroscopic flow behavior of the composites. An iterative procedure is also proposed to find out the optimum parameters. The results show that the convergence can be attained after three iterations in computation. In order to demonstrate the reliability of mi- cro-macro unified model, results based on the continuum composite model are also investigated using the stress-strain relation of composite obtained from the iterations. By comparing the proposed unified model to the continuum composite model, it is clear that the former exhibits large plastic deformation in the case of little macroscopic deformation, and the stresses and strains obtained from the submodel are higher than those from the macroscopic deformation. 展开更多
关键词 metal matrix composites micro-macro unified model submodel flow behavior MICROSTRUCTURE
原文传递
Capability requirements modeling and verification based on fuzzy ontology 被引量:4
9
作者 Qingchao Dong Zhixue Wang Weixing Zhu Hongyue He 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第1期78-87,共10页
The capability requirements of the command, control, communication, computing, intelligence, surveillance, reconnaissance (C41SR) systems are full of uncertain and vague information, which makes it difficult to mode... The capability requirements of the command, control, communication, computing, intelligence, surveillance, reconnaissance (C41SR) systems are full of uncertain and vague information, which makes it difficult to model the C41SR architecture. The paper presents an approach to modeling the capability requirements with the fuzzy unified modeling language (UML) and building domain ontologies with fuzzy description logic (DL). The UML modeling constructs are extended according to the meta model of Depart- ment of Defense Architecture Framework to improve their domain applicability, the fuzzy modeling mechanism is introduced to model the fuzzy efficiency features of capabilities, and the capability requirement models are converted into ontologies formalized in fuzzy DL so that the model consistency and reasonability can be checked with a DL reasoning system. Finally, a case study of C41SR capability requirements model checking is provided to demonstrate the availability and applicability of the method. 展开更多
关键词 fuzzy ontology fuzzy unified modeling language (UML) fuzzy description logic (DL) model checking.
在线阅读 下载PDF
Formalization and Verification of Business Process Modeling Based on UML and Petri Nets 被引量:1
10
作者 颜志军 甘仞初 《Journal of Beijing Institute of Technology》 EI CAS 2005年第2期212-216,共5页
In order to provide a quantitative analysis and verification method for activity diagrams based business process modeling, a formal definition of activity diagrams is introduced. And the basic requirements for activit... In order to provide a quantitative analysis and verification method for activity diagrams based business process modeling, a formal definition of activity diagrams is introduced. And the basic requirements for activity diagrams based business process models are proposed. Furthermore, the standardized transformation technique between business process models and basic Petri nets is presented and the analysis method for the soundness and well-structured properties of business processes is introduced. 展开更多
关键词 business process modeling unified modeling language(UML) Petri nets activity diagram
在线阅读 下载PDF
A UML profile for framework modeling 被引量:1
11
作者 徐小良 汪乐宇 周泓 《Journal of Zhejiang University Science》 CSCD 2004年第1期92-98,共7页
The current standard Unified Modeling Language(UML) could not model framework flexibility and extendibility adequately due to lack of appropriate constructs to distinguish framework hot-spots from kernel elements. A n... The current standard Unified Modeling Language(UML) could not model framework flexibility and extendibility adequately due to lack of appropriate constructs to distinguish framework hot-spots from kernel elements. A new UML profile that may customize UML for framework modeling was presented using the extension mechanisms of UML, providing a group of UML extensions to meet the needs of framework modeling. In this profile, the extended class diagrams and sequence diagrams were defined to straightforwardly identify the hot-spots and describe their instantiation restrictions. A transformation model based on design patterns was also put forward, such that the profile based framework design diagrams could be automatically mapped to the corresponding implementation diagrams. It was proved that the presented profile makes framework modeling more straightforwardly and therefore easier to understand and instantiate. 展开更多
关键词 Object oriented frameworks unified modeling Language(UML) UML profile Hot spots Design patterns
在线阅读 下载PDF
Role of attachment style in the association between childhood adversities and non-suicidal self-injury among young adults:a multigroup structural equation study
12
作者 Rodolfo Rossi Tommaso B Jannini +3 位作者 Valentina Socci Francesca Pacitti Alessandro Rossi Giorgio Di Lorenzo 《General Psychiatry》 2025年第2期103-112,共10页
Background Non-suicidal self-injury(NSSI)is a significant health concern among adolescents and young adults,often resulting from adverse childhood experiences(ACEs).Dissociation,post-traumatic symptoms and attachment ... Background Non-suicidal self-injury(NSSI)is a significant health concern among adolescents and young adults,often resulting from adverse childhood experiences(ACEs).Dissociation,post-traumatic symptoms and attachment style may have a role in shaping such associations.Aims This study aims to provide a unified model of the impact of ACEs on NSSI,exploring complex post-traumatic stress disorder(cPTSD)symptoms and dissociation as potential mediators and the role of the predominant attachment style in affecting such associations.Methods 1010 young individuals attending the last year of high school participated in this cross-sectional study.ACEs,cPTSD,dissociation and NSSI were evaluated using self-report questionnaires.We fitted a path model of NSSI,with ACEs as exogenous variables and cPTSD and dissociation as sequential mediators.Secure,fearful and preoccupied attachment styles were modelled as grouping variables.Results Our findings showed that dissociation mediated the impact of ACEs on NSSI in subjects with a fearful attachment style,as opposed to those with a preoccupied attachment for whom cPTSD symptoms mediated the ACEs-NSSI association.Conclusions Attachment styles moderate the relationship between ACEs and NSSI,with either dissociation or post-traumatic symptomatology mediating the impact of ACEs on NSSI,depending on the predominant attachment style.Our results highlight the importance of attachment as a pathway modifier in the relationships between different psychopathology dimensions,providing a useful framework to better conceptualise the ACEs-NSSI association. 展开更多
关键词 adverse childhood experiences aces dissociationpost traumatic non suicidal self injury childhood adversities complex post traumatic stress disorder attachment style DISSOCIATION unified model impact MEDIATION
暂未订购
Spatial data modeling for coalfield geological environment
13
作者 JIA Bei SU Qiao-mei LIU Chen LI Hui-juan 《Journal of Coal Science & Engineering(China)》 2010年第3期300-305,共6页
Presented a study on the design and implementation of spatial data modelingand application in the spatial data organization and management of a coalfield geologicalenvironment database.Based on analysis of a number of... Presented a study on the design and implementation of spatial data modelingand application in the spatial data organization and management of a coalfield geologicalenvironment database.Based on analysis of a number of existing data models and takinginto account the unique data structure and characteristic, methodology and key techniquesin the object-oriented spatial data modeling were proposed for the coalfield geological environment.The model building process was developed using object-oriented technologyand the Unified Modeling Language (UML) on the platform of ESRI geodatabase datamodels.A case study of spatial data modeling in UML was presented with successful implementationin the spatial database of the coalfield geological environment.The modelbuilding and implementation provided an effective way of representing the complexity andspecificity of coalfield geological environment spatial data and an integrated managementof spatial and property data. 展开更多
关键词 spatial data model OBJECT-ORIENTED unified modeling Language (UML) coal- field geological environment
在线阅读 下载PDF
Degradation of natural red mudstone subjected to long-term relative humidity cycles
14
作者 Kang Chen Rui Zhang +2 位作者 Shengyang Yuan Jie Ma Huan Wang 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第9期5800-5815,共16页
This paper presents a multi-scale experimental investigation of the weathering degradation of red mudstone.Natural rocks were extracted from the surface ground to 120 m,inwhich three sets of samples were selected to c... This paper presents a multi-scale experimental investigation of the weathering degradation of red mudstone.Natural rocks were extracted from the surface ground to 120 m,inwhich three sets of samples were selected to consider the different initial rock fabrics.The long-term relative humidity(RH)cycles under two amplitudes were imposed on red mudstone to simulate the weathering process.After RH cycles,a series of uniaxial compression tests,Brazilian splitting tests and bender-extender element tests were carried out to examine the reduction in strength and stiffness.The objective of this study is to develop an extended stress-volume framework characterizing the degradation of natural red mudstone both at microscale and macroscale.Accompanied by the irreversible swelling of the rock specimen is the progressive degradation of strength,stiffness and Poisson's ratio.A unified exponential degradation model in terms of the irreversible volumetric strain was thus proposed to capture such a degradation pattern.The effect of the initial rock fabric was evident.The highest degradation rate and potential were identified in slightly weathered specimens.Significant slaking of aggregates and crack propagation were confirmed by scanning electron microscope(SEM)micrographs,which were considered as the main consequence of structure damage leading to degradation of mechanical properties.The structure damage during RH cycles denoted the hysteresis nature in the response to the cycling hydraulic reaction,in turn causing the increase in volumetric strain.Thus,the stress-volume relation rather than the suction relation was found in more reasonable agreement with the experimental results. 展开更多
关键词 Red mudstone Weathering degradation Relative humidity cycles unified degradation model Microstructure tests
在线阅读 下载PDF
MODELING OF FMS BASED ON UML AND OPNS
15
作者 Gao Meimei Wu Zhiming (Department of Automation, Shanghai Jiaotong University) 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2000年第2期90-95,共6页
As the main component of computer integrated manufacturing system (CIMS), flexible manufacturing system (FMS) should be an open system with reusability and extenchaility. Moreover, as FMS is a complex asynchronous con... As the main component of computer integrated manufacturing system (CIMS), flexible manufacturing system (FMS) should be an open system with reusability and extenchaility. Moreover, as FMS is a complex asynchronous concurrent system, its model also should have the abilities to express the concurrency in the system and to analyze the behavior of the system. It is difficult to use any one method to model such a complex system as FMS. A modeling method using Object-oriented modeling language-unified modeling language (UML) and object-Oriented Petri nets (OPNs) is proposed. Class diagram in UML is used to represent the static relations among the objects in FMS. OPNs are used to model the dynamic behavior of the objects and conduct performance analysis. OPNs also can be used to identify the attributes and operations of the objects. The model can describe the system integrally and can be used to design FMS control software naturally. 展开更多
关键词 Flexible manufacturing system modeling Object-oriented model unified modeling language Object-oriented Pert nets (Opens)
在线阅读 下载PDF
A unified model for the formation and distribution of both conventional and unconventional hydrocarbon reservoirs 被引量:29
16
作者 Xiongqi Pang Chengzao Jia +8 位作者 Junqing Chen Maowen Li Wenyang Wang Qinhong Hu Yingchun Guo Zhangxin Chen Junwen Peng Keyu Liu Keliu Wu 《Geoscience Frontiers》 SCIE CAS CSCD 2021年第2期695-711,共17页
The discovery and large-scale exploration of unconventional oil/gas resources since 1980s have been considered as the most important advancement in the history of petroleum geology;that has not only changed the balanc... The discovery and large-scale exploration of unconventional oil/gas resources since 1980s have been considered as the most important advancement in the history of petroleum geology;that has not only changed the balance of supply and demand in the global energy market,but also improved our understanding of the formation mechanisms and distribution characteristics of oil/gas reservoirs.However,what is the difference of conventional and unconventional resources and why they always related to each other in petroliferous basins is not clear.As the differences and correlations between unconventional and conventional resources are complex challenging issues and very critical for resources assessment and hydrocarbon exploration,this paper focused on studying the relationship of formations and distributions among different oil/gas reservoirs.Drilling results of 12,237 exploratory wells in 6 representative petroliferous basins of China and distribution characteristics for 52,926 oil/gas accumulations over the world were applied to clarify the formation conditions and genetic relations of different oil/gas reservoirs in a petroliferous basin,and then to establish a unified model to address the differences and correlations of conventional and unconventional reservoirs.In this model,conventional reservoirs formed in free hydrocarbon dynamic field with high porosity and permeability located above the boundary of hydrocarbon buoyancy-driven accumulation depth limit.Unconventional tight reservoirs formed in confined hydrocarbon dynamic field with low porosity and permeability located between hydrocarbon buoyancy-driven accumulation depth limit and hydrocarbon accumulation depth limit.Shale oil/gas reservoirs formed in the bound hydrocarbon dynamic field with low porosity and ultra-low permeability within the source rock layers.More than 75%of proved reserves around the world are discovered in the free hydrocarbon dynamic field,which is estimated to contain only 10%of originally generated hydrocarbons.Most of undiscovered resources distributed in the confined hydrocarbon dynamic field and the bound hydrocarbon dynamic field,which contains 90%of original generated hydrocarbons,implying a reasonable and promising area for future hydrocarbon explorations.The buried depths of hydrocarbon dynamic fields become shallow with the increase of heat flow,and the remaining oil/gas resources mainly exist in the deep area of“cold basin”with low geothermal gradient.Lithology changing in the hydrocarbon dynamic field causes local anomalies in the oil/gas dynamic mechanism,leading to the local formation of unconventional hydrocarbon reservoirs in the free hydrocarbon dynamic field or the occurrence of oil/gas enrichment sweet points with high porosity and permeability in the confined hydrocarbon dynamic field.The tectonic movements destroy the medium conditions and oil/gas components,which leads to the transformation of conventional oil/gas reservoirs formed in free hydrocarbon dynamic field to unconventional ones or unconventional ones formed in confined and bound hydrocarbon dynamic fields to conventional ones. 展开更多
关键词 Fossil fuels Hydrocarbon resources unified model of reservoirs formation Hydrocarbon reservoirs Hydrocarbon accumulation Hydrocarbon dynamic field
在线阅读 下载PDF
Unified strength model based on the Hoek-Brown failure criterion for fibre-reinforced polymer-confined pre-damaged concrete columns with circular and square cross sections 被引量:7
17
作者 ZHANG Yang LU Zhi-fang CAO Yu-gui 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第12期3807-3820,共14页
Fibre-reinforced polymer(FRP)has the advantages of high strength,light weight,corrosion resistance and convenient construction and is widely used in repairing and strengthening damaged concrete columns.Most of the exi... Fibre-reinforced polymer(FRP)has the advantages of high strength,light weight,corrosion resistance and convenient construction and is widely used in repairing and strengthening damaged concrete columns.Most of the existing strength models were built by regression analysis of experimental data;however,in this article,a new unified strength model is proposed using the Hoek-Brown failure criterion.To study the strength of FRP-confined damaged and undamaged concrete columns,900 test data were collected from the published literature and a large database that contains the cross-sectional shape of each specimen,the damage type,the damage level and the FRP-confined stiffness was established.A new strength model using the Hoek-Brown failure criterion was established and is suitable for both circular and square columns that are undamaged,load-damaged and fire-damaged.Based on the database,most of the existing strength models from the published literature and the model proposed in this paper were evaluated.The evaluation shows that the proposed model can predict the compressive strength for FRP-confined pre-damaged and undamaged concrete columns with good accuracy. 展开更多
关键词 FRP-confined concrete load-damaged fire-damaged unified strength model Hoek-Brown failure criterion
在线阅读 下载PDF
Constitutive modeling and springback prediction of stress relaxation age forming of pre-deformed 2219 aluminum alloy 被引量:5
18
作者 Kai WANG Li-hua ZHAN +3 位作者 You-liang YANG Zi-yao MA Xi-cai LI Jian LIU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2019年第6期1152-1160,共9页
Stress relaxation ageing behavior of pre-deformed AA2219 is studied through stress relaxation age experiments and finite element(FE)simulation.The results show that the stress can promote the process of ageing precipi... Stress relaxation ageing behavior of pre-deformed AA2219 is studied through stress relaxation age experiments and finite element(FE)simulation.The results show that the stress can promote the process of ageing precipitation,and shorten the time to reach the peak strength.Meanwhile,the residual stress and yield strength increase along with the increase in the initial stress.Based on microstructure evolution and ageing strengthening theory,a unified constitutive model is established and incorporated into the FE simulation model through a user subroutine.It is found that the relative error of the radius is 3.6%compared with the experimental result and the springback is 16.8%.This indicates that the proposed stress relaxation ageing constitutive model provides a good prediction on the springback of such stiffened panel during its ageing process. 展开更多
关键词 2219 aluminum alloy stress relaxation ageing unified constitutive model SPRINGBACK
在线阅读 下载PDF
A Unified Thermodynamic Model of Flow-induced Crystallization of Polymer 被引量:4
19
作者 Cui Nie Fan Peng +3 位作者 Ting-Yu Xu Jun-Fang Sheng Wei Chen Liang-Bin Li 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2021年第11期1489-1495,共7页
We propose a unified thermodynamic model of flow-induced crystallization of polymer(uFIC),which incorporates not only the conformational entropy reduction but also the contributions of flow-induced chain orientation,t... We propose a unified thermodynamic model of flow-induced crystallization of polymer(uFIC),which incorporates not only the conformational entropy reduction but also the contributions of flow-induced chain orientation,the interaction of ordered segments,and the free energy of crystal nucleus and crystal morphology.Specifically,it clarifies the determining parameters of the critical crystal nucleus size,and is able to account for the acceleration of nucleation,the emergence of precursor,different crystal morphologies and structures induced by flow.Based on the nucleation barrier under flow,we analyze at which condition precursor may occur and how flow affects the competition among different crystal forms such as orthorhombic and hexagonal phases of polyethylene.According to the uFIC model,the different crystal morphologies and structures in the flow-temperature space have been clarified,which give a good agreement with experiments of FIC. 展开更多
关键词 Flow-induced crystallization unified thermodynamic model Flow-induced chain orientation
原文传递
Evaluation of Unified Model Microphysics in High-resolution NWP Simulations Using Polarimetric Radar Observations 被引量:1
20
作者 Marcus JOHNSON Youngsun JUNG +4 位作者 Daniel DAWSON Timothy SUPINIE Ming XUE Jongsook PARK Yong-Hee LEE 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2018年第7期771-784,共14页
The UK Met Office Unified Model(UM) is employed by many weather forecasting agencies around the globe. This model is designed to run across spatial and time scales and known to produce skillful predictions for large... The UK Met Office Unified Model(UM) is employed by many weather forecasting agencies around the globe. This model is designed to run across spatial and time scales and known to produce skillful predictions for large-scale weather systems. However, the model has only recently begun running operationally at horizontal grid spacings of ~1.5 km [e.g.,at the UK Met Office and the Korea Meteorological Administration(KMA)]. As its microphysics scheme was originally designed and tuned for large-scale precipitation systems, we investigate the performance of UM microphysics to determine potential inherent biases or weaknesses. Two rainfall cases from the KMA forecasting system are considered in this study: a Changma(quasi-stationary) front, and Typhoon Sanba(2012). The UM output is compared to polarimetric radar observations in terms of simulated polarimetric radar variables. Results show that the UM generally underpredicts median reflectivity in stratiform rain, producing high reflectivity cores and precipitation gaps between them. This is partially due to the diagnostic rain intercept parameter formulation used in the one-moment microphysics scheme. Model drop size is generally both underand overpredicted compared to observations. UM frozen hydrometeors favor generic ice(crystals and snow) rather than graupel, which is reasonable for Changma and typhoon cases. The model performed best with the typhoon case in terms of simulated precipitation coverage. 展开更多
关键词 unified Model MICROPHYSICS polarimetric radar radar simulator numerical weather prediction
在线阅读 下载PDF
上一页 1 2 4 下一页 到第
使用帮助 返回顶部