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A Rigorous Architectural Approach to Adaptive software Engineering

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Journal of Computer science & Technology 2009年第2期24卷 183-188页

作者： Jeff Kramere Jeff Magee department of computing Imperial College London

The engineering of distributed adaptive software is a complex task which requires a rigorous approach. software architectural （structural） concepts and principles are highly beneficial in specifying, designing, analysing, constructing and evolving distributed software. A rigorous architectural approach dictates formalisms and techniques that are compositional, components that are context independent and systems that can be constructed and evolved incrementally. This paper overviews some of the underlying reasons for adopting an architectural approach, including a brief ＂rational history＂ of our research work, and indicates how an architectural model can potentially facilitate the provision of self-managed adaptive software system.

关键词： adaptiye systems self-managed systems autonomic systems software architecture

IC Cloud: Enabling Compositional Cloud

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International Journal of Automation and computing 2011年第3期8卷 269-279页

作者： Yi-Ke Guo Li Guo department of computing Imperial College London London SW7 2BZ UK

Cloud computing has attracted great interest from both academic and industrial communities. Different paradigms, architectures and applications based on the concept of cloud have emerged. Although many of them have been quite successful, efforts are mainly focusing on the study and implementation of particular setups. However, a generic and more flexible solution for cloud construction is missing. In this paper, we present a composition-based approach for cloud computing （compositional cloud） using imperial college Cloud （IC Cloud） as a demonstration example. Instead of studying a specific cloud computing system, our approach aims to enable a generic framework where wrious cloud computing architectures and implementation strategies can be systematically studied. With our approach, cloud computing providers/adopters are able to design and compose their own systems in a quick and flexible manner. Cloud computing systems will no longer be in fixed shapes but will be dynamic and adjustable according to the requirements of different application domains.

关键词： Cloud computing compositional cloud infrastructure as a service (Iaas) cloud service cloud elasticity.

A Creative Approach to Reducing Ambiguity in scenario-based software Architecture Analysis

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International Journal of Automation and computing 2019年第2期16卷 248-260页

作者： Xi-Wen Wu Chen Li Xuan Wang Hong-Ji Yang department of Computer science and Engineering Shanghai Jiao Tong University department of computing Imperial College London Center for Creative computing Bath Spa University

In software engineering, a scenario describes an anticipated usage of a software system. As scenarios are useful to understand the requirements and functionalities of a software system, the scenario-based analysis is widely used in various tasks, especially in the design stage of software architectures. Although researchers have proposed various scenario-based approaches to analyse software architecture, there are still limitations in this research field, and a key limitation is that scenarios are typically not formally defined and thus may contain ambiguities. As these ambiguities may lead to defects, it is desirable to reduce them as many as possible. In order to reduce ambiguity in scenario-based software architecture analysis, this paper introduces a creative computing approach to scenario-based software requirements analysis. Our work expands this idea in three directions. Firstly, we extend an architecture description language(ADL)-based language – Breeze/ADL to model the software architecture. secondly, we use a creative rule – combinational rule(CR) to combine the vector clock algorithm for reducing the ambiguities in modelling scenarios. Then, another creative rule – transformational rule(TR) is employed to help to transform our Breeze/ADL model to a popular model – unified modelling language(UML) model. We implement our approach as a plugin of Breeze, and illustrate a running example of modelling a poetry to music system in our case *** results show the proposed creative approach is able to reduce ambiguities of the software architecture in practice.

关键词： Creative computing vector clock algorithm scenario-based analysis of software architecture sequence diagram Breeze/ architecture description language (ADL)

Effective Variational Data Assimilation in Air-Pollution Prediction

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Big Data Mining and Analytics 2018年第4期1卷 297-307页

作者： Rossella Arcucci Christopher Pain Yi-Ke Guo Data science Institute Department of ComputingImperial College LondonLondonSW72AZUnited Kingdom department of Earth science&Engineering Imperial College LondonLondonSW72AZUnited Kingdom

Numerical simulations are widely used as a predictive tool to better understand complex air flows and pollution transport on the scale of individual buildings,city blocks,and entire *** improve prediction for air flows and pollution transport,we propose a Variational Data Assimilation(VarDA)model which assimilates data from sensors into the open-source,finite-element,fluid dynamics model *** is based on the minimization of a function which estimates the discrepancy between numerical results and observations assuming that the two sources of information,forecast and observations,have errors that are adequately described by error covariance *** conditioning of the numerical problem is dominated by the condition number of the background error covariance matrix which is *** this paper,a preconditioned VarDA model is presented,it is based on a reduced background error covariance *** Empirical Orthogonal Functions(EOFs)method is used to alleviate the computational cost and reduce the space *** results are provided assuming observed values provided by sensors from positions mainly located on roofs of buildings.

关键词： data assimilation reduced order space big data preconditioning

Inferring Functional Connectivity in fMRI Using Minimum Partial Correlation

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International Journal of Automation and computing 2017年第4期14卷 371-385页

作者： Lei Nie Xian Yang Paul M. Matthews Zhi-Wei Xu Yi-Ke Guo department of computing Imperial College London London SW7 2AZ UK department of Medicine Imperial College London London SW7 2AZ UK Institute of computing Technology Chinese Academy of Sciences Beijing 100190 China school of Computer Engineering and science Shanghai University Shanghai 200444 China

Functional connectivity has emerged as a promising approach to study the functional organisation of the brain and to define features for prediction of brain state. The most widely used method for inferring functional connectivity is Pearson＇s correlation, but it cannot differentiate direct and indirect effects. This disadvantage is often avoided by computing the partial correlation between two regions controlling all other regions, but this method suffers from Berkson＇s paradox. some advanced methods, such as regularised inverse covariance, have been applied. However, these methods usually depend on some parameters. Here we propose use of minimum partial correlation as a parameter-free measure for the skeleton of functional connectivity in functional magnetic resonance imaging （flVIRI）. The minimum partial correlation between two regions is the minimum of absolute values of partial correlations by controlling all possible subsets of other regions. Theoretically, there is a direct effect between two regions if and only if their minimum partial correlation is non-zero under faithfulness and Gaussian assumptions. The elastic PC-algorithm is designed to efficiently approximate minimum partial correlation within a computational time budget. The simulation study shows that the proposed method outperforms others in most cases and its application is illustrated using a resting-state fMRI dataset from the human connectome project.

关键词： Functional connectivity functional magnetic resonance imaging (fMRI) network modelling partial correlation PC-algorithm resting-state networks.

ECC:Edge Collaborative Caching strategy for Differentiated services Load-Balancing

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Computers, Materials & Continua 2021年第11期69卷 2045-2060页

作者： Fang Liu Zhenyuan Zhang Zunfu Wang Yuting Xing school of Design Hunan UniversityChangshaChina school of Computer science and Engineering Sun Yat-Sen UniversityGuangzhouChina department of computing Imperial College LondonUK

Due to the explosion of network data traffic and IoT devices,edge servers are overloaded and slow to respond to the massive volume of online requests.A large number of studies have shown that edge caching can solve this problem *** paper proposes a distributed edge collaborative caching mechanism for Internet online request services *** solves the problem of large average access delay caused by unbalanced load of edge servers,meets users’differentiated service demands and improves user *** particular,the edge cache node selection algorithm is optimized,and a novel edge cache replacement strategy considering the differentiated user requests is *** mechanism can shorten the response time to a large number of user *** results show that,compared with the current advanced online edge caching algorithm,the proposed edge collaborative caching strategy in this paper can reduce the average response delay by 9%.It also increases the user utility by 4.5 times in differentiated service scenarios,and significantly reduces the time complexity of the edge caching algorithm.

关键词： Edge collaborative caching differentiated service cache replacement strategy load balancing

A High-order Internal Model Based Iterative Learning Control scheme for Discrete Linear Time-varying systems

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International Journal of Automation and computing 2015年第3期12卷 330-336页

作者： Wei Zhou Miao Yu De-Qing Huang college of Electrical Engineering Zhejiang University college of Engineering Jiangsu Institute of Commerce department of Aeronautics Imperial College London

In this paper, an iterative learning control algorithm is proposed for discrete linear time-varying systems to track iterationvarying desired trajectories. A high-order internal model(HOIM) is utilized to describe the variation of desired trajectories in the iteration domain. In the sequel, the HOIM is incorporated into the design of learning gains. The learning convergence in the iteration axis can be guaranteed with rigorous proof. The simulation results with permanent magnet linear motors(PMLM) demonstrate that the proposed HOIM based approach yields good performance and achieves perfect tracking.

关键词： Iterative learning control high-order internal model discrete linear time-varying systems iteration-varying desired tra-jectory

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Time-in-action RL

IET Cyber-systems and Robotics 2019年第1期1卷 28-37页

作者： Jiangcheng Zhu Zhepei Wang Douglas Mcilwraith Chao Wu Chao Xu Yike Guo Institute of Cyber-systems and Control Department of Control Science and EngineeringZhejiang UniversityHangzhouPeople's Republic of China Data science Institute Department of ComputingImperial College LondonLondonUK school of Public Affairs Zhejiang UniversityHangzhouPeople's Republic of China

The authors propose a novel reinforcement learning(RL)framework,where agent behaviour is governed by traditional control *** integrated approach,called time-in-action RL,enables RL to be applicable to many real-world systems,where underlying dynamics are known in their control theoretical *** key insight to facilitate this integration is to model the explicit time function,mapping the state-action pair to the time accomplishing the action by its underlying *** their framework,they describe an action by its value(action value),and the time that it takes to perform(action time).An action-value results from the policy of RL regarding a *** time is estimated by an explicit time model learnt from the measured activities of the underlying *** value network is then trained with embedded time model to predict action *** approach is tested using a variant of Atari Pong and proved to be convergent.

关键词： action policy agent

Accelerating GW calculations through machine-learned dielectric matrices

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npj Computational Materials 2023年第1期9卷 437-445页

作者： Mario G.Zauchner Andrew Horsfield Johannes Lischner department of Materials Thomas Young CentreImperial College LondonSouth Kensington CampusLondon SW72AZUK

The GW approach produces highly accurate quasiparticle energies,but its application to large systems is computationally challenging due to the difficulty in computing the inverse dielectric *** address this challenge,we develop a machine learning approach to efficiently predict density–density response functions(DDRF)in *** atomic decomposition of the DDRF is introduced,as well as the neighborhood density–matrix descriptor,both of which transform in the same way under *** resulting DDRFs are then used to evaluate quasiparticle energies via the GW *** assess the accuracy of this method,we apply it to hydrogenated silicon clusters and find that it reliably reproduces HOMO–LUMO gaps and quasiparticle energy *** accuracy of the predictions deteriorates when the approach is applied to larger clusters than those in the training *** advances pave the way for GW calculations of complex systems,such as disordered materials,liquids,interfaces,and nanoparticles.

关键词： materials dielectric quasi