28 results on '"Gelenbe, Erol"'
Search Results
2. Randomization of Data Generation Times Improves Performance of Predictive IoT Networks
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Nakıip, Mert and Gelenbe, Erol
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Earliest deadline first scheduling ,Scheduling ,Massive Access Problem ,business.industry ,Computer science ,Test data generation ,Network packet ,Quality of service ,Throughput ,Internet of Things (IoT) ,Predictive networks ,Packet loss ,Logic gate ,Performance improvement ,business ,Computer network - Abstract
Input traffic from Internet of Things (IoT) devices is often both periodic and requires to be received by a given deadline. This can create congestion at instants of time when traffic flowing from multiple devices arrives at a shared input port or gateway, resulting in missed deadlines at the receiver.As a consequence, scheduling techniques such as the “Earliest Deadline First” (EDF) and “Priority based on Average Load” (PAL) are used to schedule the flow from different devices so as to try to satisfy the needs of the largest number of traffic flows in a timely fashion. In this paper, we propose the Randomization of flow Generation Times (RGT) in order to smooth the total incoming traffic to the input port or gateway, on top of the use of EDF and PAL. We then evaluate the performance of RGT together with PAL and EDP, for traffic load with a varyingnumber of up to 6400 IoT devices. Our simulation results show that RGT provides significantly better performance when added to EDF and PAL. Also, the additional computation required by RGT at each device can be quite small, suggesting that RGT is a very useful addition for improving the performance of IoT networks.
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- 2021
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3. Product-Form Solution for Cascade Networks With Intermittent Energy
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Kadioglu Yasin Murat, Gelenbe Erol, and Engineering & Physical Science Research Council (EPSRC)
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Technology ,system workload ,Computer science ,Distributed computing ,0211 other engineering and technologies ,product-form solution ,system performance ,02 engineering and technology ,Energy packet (EP) network ,Job queue ,N-node tandem system ,PFS ,queueing networks ,Engineering ,energy packets (EP) network ,intermittent energy supply ,Throughput (business) ,production lines ,Queueing theory ,Computer Science, Information Systems ,job queue length ,021103 operations research ,Operations Research & Management Science ,Product-form solution ,queueing network models ,Computer Science Applications ,Telecommunications ,Information Systems ,energy harvesting ,Operations Research ,Computer Networks and Communications ,multihop networks ,Supply chain ,power grid ,digital devices ,manufacturing systems ,Energy supply ,Electrical and Electronic Engineering ,cascade networks ,supply chains ,local storage batteries ,intermittent nature ,simultaneous state transitions ,Science & Technology ,product-form solution (PFS) ,Node (networking) ,Engineering, Electrical & Electronic ,digital systems ,possible energy leakage ,Control and Systems Engineering ,Computer Science ,interconnected systems ,Energy (signal processing) - Abstract
The power needs of digital devices, their installation in locations where it is difficult to connect them to the power grid and the difficulty of frequently replacing batteries, create the need to operate digital systems with harvested energy. In such cases, local storage batteries must overcome the intermittent nature of the energy supply. System performance then depends on the intermittent energy supply, possible energy leakage, and system workload. Queueing networks with product-form solution (PFS) are standard tools for analyzing the performance of interconnected systems, and predicting relevant performance metrics including job queue lengths, throughput, and system turnaround times and delays. However, existing queueing network models assume unlimited energy availability, whereas intermittently harvested energy can affect system performance due to insufficient energy supply. Thus, this paper develops a new PFS for the joint probability distribution of energy availability, and job queue length for an N-node tandem system. Such models can represent production lines in manufacturing systems, supply chains, cascaded repeaters for optical links, or a data link with multiple input data ports that feeds into a switch or server. Our result enables the rigorous computation of the relevant performance metrics of such systems operating with intermittent energy.
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- 2019
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4. Security in Computer and Information Sciences
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Gelenbe, Erol, Campegiani, Paolo, Czachórski, Tadeusz, Katsikas, Sokratis K., Komnios, Ioannis, Romano, Luigi, and Tzovaras, Dimitrios
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Computer science ,Data protection ,Application software ,Data encryption (Computer science) ,Special purpose computers ,Computer communication systems ,thema EDItEUR::G Reference, Information and Interdisciplinary subjects::GP Research and information: general::GPJ Coding theory and cryptology ,thema EDItEUR::U Computing and Information Technology::UK Computer hardware::UKN Network hardware ,thema EDItEUR::U Computing and Information Technology::UN Databases::UNH Information retrieval ,thema EDItEUR::U Computing and Information Technology::UR Computer security ,thema EDItEUR::U Computing and Information Technology::UY Computer science::UYQ Artificial intelligence::UYQE Expert systems / knowledge-based systems - Abstract
This open access book constitutes the thoroughly refereed proceedings of the First International ISCIS Security Workshop 2018, Euro-CYBERSEC 2018, held in London, UK, in February 2018. The 12 full papers presented together with an overview paper were carefully reviewed and selected from 31 submissions. Security of distributed interconnected systems, software systems, and the Internet of Things has become a crucial aspect of the performance of computer systems. The papers deal with these issues, with a specific focus on societally critical systems such as health informatics systems, the Internet of Things, energy systems, digital cities, digital economy, mobile networks, and the underlying physical and network infrastructures.
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- 2018
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5. Storms in mobile networks
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Gorbil, Gokce, Abdelrahman, Omer H., Pavloski, Mihajlo, and Gelenbe, Erol
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Networking and Internet Architecture (cs.NI) ,FOS: Computer and information sciences ,Service (systems architecture) ,Computer Science - Cryptography and Security ,business.industry ,Computer science ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,cs.NI ,Botnet ,computer.software_genre ,Radio Resource Control ,Network simulation ,Computer Science - Networking and Internet Architecture ,Signalling ,cs.CR ,Cellular network ,Malware ,business ,Cryptography and Security (cs.CR) ,computer ,Protocol (object-oriented programming) ,Computer network - Abstract
Mobile networks are vulnerable to signalling attacks and storms that are caused by traffic patterns that overload the control plane, and differ from distributed denial of service (DDoS) attacks in the Internet since they directly attack the control plane, and also reserve wireless bandwidth without actually using it. Such attacks can result from malware and mobile botnets, as well as from poorly designed applications, and can cause service outages in 3G and 4G networks which have been experienced by mobile operators. Since the radio resource control (RRC) protocol in 3G and 4G networks is particularly susceptible to such attacks, we analyze their effect with a mathematical model that helps to predict the congestion that is caused by an attack. A detailed simulation model of a mobile network is used to better understand the temporal dynamics of user behavior and signalling in the network and to show how RRC based signalling attacks and storms cause significant problems in the control plane and the user plane of the network. Our analysis also serves to identify how storms can be detected, and to propose how system parameters can be chosen to mitigate their effect., Submitted to the IEEE TETC special issue on "Emerging topics in Cyber Security"
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- 2014
6. Steps Toward Self-Aware Networks.
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GELENBE, EROL
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COMPUTER network management , *AUTONOMIC computing , *ELECTRONIC data processing , *COMPUTER network protocols , *QUALITY of service , *COMPUTER science - Abstract
The article discusses the design of self-aware networks (SANs), examining the theoretical and experimental research concerning the technical procedures necessary to establish such networks. SANs are comprised of nodes that can autonomously join and leave a network, as well as discover paths when a need to communicate arises. Other topics of discussion include connections that use paths which optimize the connections own quality of service (QoS) criteria and bio-inspired techniques for networking.
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- 2009
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7. Runtime Verification of Component-Based Embedded Software
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Sözer, Hasan, Hofmann, C., Tekinerdogan, B., Aksit, Mehmet, Gelenbe, Erol, Lent, Ricardo, Sakellari, Georgia, Özyeğin University, and Sözer, Hasan
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Computer science ,Component based ,Embedded systems ,Information science ,IR-78300 ,Fault Tolerance ,Runtime behaviors ,EWI-20659 ,Specifications ,Software Architecture ,Component (UML) ,Run-time verification ,Levels of abstraction ,Software system ,METIS-281539 ,Component-based software development ,Software visualization ,Run-time errors ,Error-detection mechanism ,business.industry ,Runtime verification ,Software development ,SE-SA: Software Architecture ,Component-based development ,Embedded software ,Embedded system ,Software construction ,Component-based software engineering ,Working mode ,business ,Embedded Systems - Abstract
Date of Conference: 26-28 September 2011 Conference name: Computer and Information Sciences II - 26th International Symposium on Computer and Information Sciences To deal with increasing size and complexity, component-based software development has been employed in embedded systems. Due to several faults, components can make wrong assumptions about the working mode of the system and the working modes of the other components. To detect mode inconsistencies at runtime, we propose a "lightweight" error detection mechanism, which can be integrated with component-based embedded systems. We define links among three levels of abstractions: the runtime behavior of components, the working mode specifications of components and the specification of the working modes of the system. This allows us to detect the user observable runtime errors. The effectiveness of the approach is demonstrated by implementing a software monitor integrated into a TV system. © 2012 Springer-Verlag London Limited.
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- 2011
8. Support for Resilient Communications in Future Disaster Management
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Jones, Valerie M., Karagiannis, Georgios, Heemstra de Groot, S.M., Gelenbe, Erol, Lent, Ricardo, and Sakellari, Georgia
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Vehicular ad hoc network ,Access network ,BAN ,Emergency management ,Resilience ,Computer science ,business.industry ,Wireless network ,Wireless communications ,EWI-20465 ,MANETS ,QoS ,Communications management ,Critical infrastructure ,Health Monitoring ,GAN ,Wireless ,METIS-279174 ,Vehicular Networks ,Resilience (network) ,business ,Telecommunications ,Disaster Management ,IR-78280 - Abstract
Disasters are often accompanied by damage to critical infrastructure, including (wireless) communications infrastructure. Our solution for emergency communications is based on advanced networks: Generalized Access Networks (GANs), Body Area Networks (BANs) and Vehicular Networks, to support dynamic, resilient communication services for disaster management.
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- 2011
9. Analysis of Automated Auctions.
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Levi, Albert, Savaş, Erkay, Yenigün, Hüsnü, Balcısoy, Selim, Saygın, Yücel, and Gelenbe, Erol
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Web based computerised auctions are increasingly present in the Internet, and we can imagine that in the future automated buyer and seller agents will conduct automated transactions in this manner. The purpose of this paper is to model automated bidders and sellers which interact through a computerised auction. We model bidding process using random processes with discrete state-space. We obtain analytical solutions for a variety of single auction models, including English and Vickrey auctions, and relate the income per unit time to the other parameters including the rate of arrival of bids, the seller's decision time, the value of the good, and the "rest time" of the seller between successive auctions. We examine how the seller's "decision time" impacts the expected income per unit time received by the seller, and illustrate its effect via numerical examples. [ABSTRACT FROM AUTHOR]
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- 2006
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10. User Cooperation and Search in Intelligent Networks.
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Gelenbe, Erol, Stavrakakis, Ioannis, and Smirnov, Michael
- Abstract
We present a vision of an Intelligent Network in which users dynamically indicate their requests for services, and formulate needs in terms of Quality of Service (QoS), duration, and pricing. Users can also monitor on-line the extent to which their requests are being satisfied. In turn, services will dynamically try to satisfy the users as best as they can, and inform the user of the level at which the requests are being satisfied, and at what cost. The network will provide guidelines and constraints to users and services, to avoid that they impede each others’ progress. This intelligent and sensible dialogue between users, services and the network can proceed constantly based on mutual observation, network and user self-observation, and on-line adaptive and distributed feedback control which proceeds at the same speed as changes in traffic flows and the events occurring in the network. We survey some of the technical problems that arise in such networks, illustrate the networked system we propose via an experimental test-bed based on the Cognitive Packet Network (CPN), and discuss the key issue of search for users and services. Keywords: Network Intelligence, Autonomic Networks, Users and Services, User Goals and Quality of Service, Cognitive Packet Networks. [ABSTRACT FROM AUTHOR]
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- 2006
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11. Keeping Viruses Under Control.
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Yolum, Pınar, Güngör, Tunga, Gürgen, Fikret, Özturan, Can, and Gelenbe, Erol
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We introduce a probability model for populations of conflicting agents such as computer software (cells) and computer viruses that interact in the presence of an anti-viral agent. Cells can be infected by viruses, and their longevity and ability to avoid infection is modified if they survive successive attacks by viruses. Viruses that survive the effect of the anti-viral agent may find that their ability to survive a future encounter with molecules of the anti-viral agent is modified, as is their ability to infect a uninfected cell. Additionally, we assume that the anti-viral agent can be a cocktail with different proportions of agents that target different strains of the virus. In this paper, we give the state equations for the model and prove its analytical solution in steady state. The solution then provides insight into the approriate mix or "cocktail" of anti-viral agents that are designed to deal with the virus' ability to mutate. In particular, the analysis shows that the concentration of anti-viral agent by itself does not suffice to ultimately control the infection, and that it is important to dose a mix of anti-viral agents so as to target each strain of virus in a specific manner, taking into account the ability of each virus strain to survive in the presence of the anti-viral agent. Keywords: Computer Viruses, Conflicts between Agents, Network Security. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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12. Users and Services in Intelligent Networks.
- Author
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Cho, Kenjiro, Jacquet, Philippe, and Gelenbe, Erol
- Abstract
We present a vision of an Intelligent Network in which users dynamically indicate their requests for services, and formulate needs in terms of Quality of Service (QoS) and price. Users can also monitor on-line the extent to which their requests are being satisfied. In turn the services will dynamically try to satisfy the user as best as they can, and inform the user of the level at which the requests are being satisfied, and at what cost. The network will provide guidelines and constraints to users and services, to avoid that they impede each others' progress. This intelligent and sensible dialogue between users, services and the network can proceed constantly based on mutual observation, network and user self-observation, and on-line adaptive and locally distributed feedback control which proceeds at the same speed as the traffic flows and events being controlled. We review issues such as network "situational awareness", self-organisation, and structure, and relate these concepts to the ongoing research on autonomic communication systems. We relate the search for services in the network to the question of QoS and routing. We examine the need to dynamically protect the networked system from denial of service (DoS) attacks, and propose an approch to DoS defence which uses the detection of violations of QoS constraints and the automatic throttling or dropping of traffic to protect critacl nodes. We also discuss how this vision of an Intelligent Network can benefit from techniques that have been experimented in the Cognitive Packet Network (CPN) test-bed at Imperial College, thanks to "smart packets" and reinforcement learning, which offers routing that is dynamically modified using on on-line sensing and monitoring, based on users' QoS needs and overall network objectives. [ABSTRACT FROM AUTHOR]
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- 2005
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13. Learning in genetic algorithms.
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Goos, Gerhard, Hartmanis, Juris, Leeuwen, Jan, Sipper, Moshe, Mange, Daniel, Pérez-Uribe, Andrés, and Gelenbe, Erol
- Abstract
Learning in artificial neural networks is often cast as the problem of "teaching" a set of stimulus-response (or input-output) pairs to an appropriate mathematical model which abstracts certain known properties of neural networks. A paradigm which has been developed independently of neural network models are genetic algorithms (GA). In this paper we introduce a mathematical framework concerning the manner in which genetic algorithms can learn, and show that gradient descent can be used in this frameork as well. In order to develop this theory, we use a class of stochastic genetic algorithms (GA) based on a population of chromosomes with mutation and crossover, as well as fitness, which we have described earlier in [18]. [ABSTRACT FROM AUTHOR]
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- 1998
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14. Adaptive Random Re-Routing for Differentiated QoS in Sensor Networks.
- Author
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GELENBE, EROL and NGAI, EDITH
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SENSOR networks , *QUALITY of service , *COMPUTER networks , *ELECTRONIC data processing , *COMPUTER science - Abstract
Sensor networks (SNs) consist of spatially distributed sensors which monitor an environment, and which are connected to some sinks or backbone system to which the sensor data is being forwarded. In many cases, the sensor nodes themselves can serve as intermediate nodes for data coming from other nodes, on the way to the sinks. Much of the traffic carried by SNs will originate from routine measurements or observations by sensors that monitor a particular situation, such as the temperature and humidity in a room or the infrared observation of the perimeter of a house, so that the volume of routine traffic resulting from such observations may be quite high. When important and unusual events occur, such as a sudden fire breaking out or the arrival of an intruder, it will be necessary to convey this new information very urgently through the network to a designated set of sink nodes where this information can be processed and dealt with. This paper addresses the important challenge by avoiding the routine background traffic from creating delays or bottlenecks that impede the rapid delivery of high priority traffic resulting from the unusual events. Specifically we propose a novel technique, the ‘Randomized Re-Routing Algorithm (RRR)’, which detects the presence of novel events in a distributed manner, and dynamically disperses the background traffic towards secondary paths in the network, while creating a ‘fast track path’ which provides better delay and better quality of service (QoS) for the high priority traffic which is carrying the new information. When the surge of new information has subsided, this is again detected by the nodes and the nodes progressively revert to best QoS or shortest-path routing for all the ongoing traffic. The proposed technique is evaluated using a mathematical model as well as simulations, and is also compared with a standard node by a node priority scheduling technique. [ABSTRACT FROM PUBLISHER]
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- 2010
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15. Energy-Efficient Cloud Computing.
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BERL, ANDREAS, GELENBE, EROL, DI GIROLAMO, MARCO, GIULIANI, GIOVANNI, DE MEER, HERMANN, MINH QUAN DANG, and PENTIKOUSIS, KOSTAS
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CLOUD computing , *ENERGY consumption , *INFORMATION technology , *COMPUTER systems , *COMPUTER science - Abstract
Energy efficiency is increasingly important for future information and communication technologies (ICT), because the increased usage of ICT, together with increasing energy costs and the need to reduce green house gas emissions call for energy-efficient technologies that decrease the overall energy consumption of computation, storage and communications. Cloud computing has recently received considerable attention, as a promising approach for delivering ICT services by improving the utilization of data centre resources. In principle, cloud computing can be an inherently energy-efficient technology for ICT provided that its potential for significant energy savings that have so far focused on hardware aspects, can be fully explored with respect to system operation and networking aspects. Thus this paper, in the context of cloud computing, reviews the usage of methods and technologies currently used for energy-efficient operation of computer hardware and network infrastructure. After surveying some of the current best practice and relevant literature in this area, this paper identifies some of the remaining key research challenges that arise when such energy-saving techniques are extended for use in cloud computing environments. [ABSTRACT FROM PUBLISHER]
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- 2010
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16. Editorial.
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GELENBE, EROL
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COMPUTERS , *COMPUTER science - Abstract
The article discusses the history and accomplishments of "The Computer Journal."
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- 2010
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17. Performance of Selection Hyper-heuristics on the Extended HyFlex Domains
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Warren G. Jackson, Ahmed Kheiri, Alhanof Almutairi, Ender Özcan, Czachórski, Tadeusz, Gelenbe, Erol, Grochla, Krzysztof, and Lent, Ricardo
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Mathematical optimization ,Theoretical computer science ,Computer science ,020207 software engineering ,02 engineering and technology ,Domain (software engineering) ,Set (abstract data type) ,Quadratic equation ,Mixing (mathematics) ,Knapsack problem ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Heuristics ,Metaheuristic ,Selection (genetic algorithm) - Abstract
Selection hyper-heuristics perform search over the space of heuristics by mixing and controlling a predefined set of low level heuristics for solving computationally hard combinatorial optimisation problems. Being reusable methods, they are expected to be applicable to multiple problem domains, hence performing well in cross-domain search. HyFlex is a general purpose heuristic search API which separates the high level search control from the domain details enabling rapid development and performance comparison of heuristic search methods, particularly hyper-heuristics. In this study, the performance of six previously proposed selection hyper-heuristics are evaluated on three recently introduced extended HyFlex problem domains, namely 0–1 Knapsack, Quadratic Assignment and Max-Cut. The empirical results indicate the strong generalising capability of two adaptive selection hyper-heuristics which perform well across the ‘unseen’ problems in addition to the six standard HyFlex problem domains.
- Published
- 2016
18. Occupancy Detection for Building Emergency Management Using BLE Beacons
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William Oliff, George Loukas, Avgoustinos Filippoupolitis, Czachórski, Tadeusz, Gelenbe, Erol, Grochla, Krzysztof, and Lent, Ricardo
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Emergency personnel ,Emergency management ,Occupancy ,business.industry ,Computer science ,computer.internet_protocol ,Real-time computing ,0102 computer and information sciences ,02 engineering and technology ,01 natural sciences ,Emergency situations ,QA76 ,law.invention ,Beacon ,010201 computation theory & mathematics ,law ,Mobile phone ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,business ,computer ,Remote control ,Simulation ,Bluetooth Low Energy - Abstract
Being able to reliable estimate the occupancy of areas inside a building can prove beneficial for managing an emergency situation, as it allows for more efficient allocation of resources such as emergency personnel. In indoor environments, however, occupancy detection can be a very challenging task. A solution to this can be provided by the use of Bluetooth Low Energy (BLE) beacons installed in the building. In this work we evaluate the performance of a BLE based occupancy detection system geared towards emergency situations that take place inside buildings. The system is composed of BLE beacons installed inside the building, a mobile application installed on occupants' mobile phones and a remote control server. Our approach does not require any processing to take place on the occupants' mobile phones, since the occupancy detection is based on a classifier installed on the remote server. Our real-world experiments indicated that the system can provide high classification accuracy for different numbers of installed beacons and occupant movement patterns.
- Published
- 2016
19. A Role and Activity Based Access Control for Secure Healthcare Systems
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Naim Alperen Pulur, Duygu Karaoğlan Altop, Albert Levi, Abdelrahman, Omer H., Gelenbe, Erol, Gorbil, Gökçe, and Lent, Ricardo
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Computer access control ,Computer science ,business.industry ,Medical record ,Internet privacy ,020206 networking & telecommunications ,Context (language use) ,Access control ,02 engineering and technology ,Login ,Computer security ,computer.software_genre ,Order (exchange) ,020204 information systems ,0202 electrical engineering, electronic engineering, information engineering ,Role-based access control ,business ,computer ,Data transmission - Abstract
We introduce a novel access control mechanism in order to safeguard privacy of medical data of patients in dynamic environments. Our access control model takes advantages from role-based access control (RBAC) and criticality aware access control (CAAC). In this way, our original approach allows the medical professionals with different roles to be granted access to medical records of patients automatically and without explicit request in case of a medical emergency. In this context, we design secure and privacy aware protocols from initial login to patients' medical data transmission and retrieval by the medical professionals. Moreover, we formally define access control policies for our system. Finally we show the feasibility of our approach by implementation and performance evaluation.
- Published
- 2015
20. Uneven key pre-distribution scheme for multi-phase wireless sensor networks
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Albert Levi, Onur Catakoglu, Gelenbe, Erol, and Lent, Ricardo
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Scheme (programming language) ,Key distribution in wireless sensor networks ,Multi phase ,Software deployment ,Computer science ,Distributed computing ,Node (networking) ,Key (cryptography) ,computer ,Wireless sensor network ,Pre distribution ,computer.programming_language - Abstract
In multi-phase Wireless Sensor Networks (WSNs), sensor nodes are redeployed periodically to replace nodes whose batteries are depleted. In order to keep the network resilient against node capture attacks across different deployment epochs, called generations, it is necessary to refresh the key pools from which cryptographic keys are distributed. In this paper, we propose Uneven Key Pre-distribution (UKP) scheme that uses multiple different key pools at each generation. Our UKP scheme provides self healing that improves the resiliency of the network at a higher level as compared to an existing scheme in the literature. Moreover, our scheme provides perfect local and global connectivity. We conduct our simulations in mobile environment to see how our scheme performs under more realistic scenarios.
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- 2013
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21. Performance Evaluation of Different CRL Distribution Schemes Embedded in WMN Authentication
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Albert Levi, Ahmet Onur Durahim, İsmail Fatih Yıldırım, Erkay Savas, Gelenbe, Erol, and Lent, Ricardo
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Router ,Task (computing) ,Authentication ,Access network ,Revocation ,Wireless mesh network ,business.industry ,Computer science ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Scalability ,Certification ,business ,Computer network - Abstract
Wireless Mesh Networks (WMNs) have emerged as a promising technology to provide low cost and scalable solutions for high speed Internet access and additional services. In hybrid WMNs, where mesh clients also act as relaying agents and form a mesh client network, it is important to provide users with an efficient anonymous and accountable authentication scheme. Accountability is required for the malicious users that are to be identified and revoked from the network access and related services. Promising revocation schemes are based on Certification Revocation Lists (CRLs). Since in hybrid WMNs mesh clients also authenticate other clients, distribution of these CRLs is an important task. In this paper, we propose and examine the performance of different distribution schemes of CRLs and analyze authentication performance in two scenarios: in one scenario all mesh routers and mesh clients obtain CRLs and in the second one, CRLs are held only by the mesh routers and mesh clients acting as relaying agents require CRL checking to be performed from the router in authenticating another client.
- Published
- 2012
22. A distributed scheme to detect wormhole attacks in mobile wireless sensor networks
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Oya Simsek, Albert Levi, Gelenbe, Erol, Lent, Ricardo, and Sakellari, Georgia
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Scheme (programming language) ,business.industry ,Computer science ,Clock synchronization ,Key distribution in wireless sensor networks ,Mobile wireless sensor network ,False positive rate ,Wormhole ,business ,Focus (optics) ,computer ,Wireless sensor network ,computer.programming_language ,Computer network - Abstract
Due to mostly being unattended, sensor nodes become open to physical attacks such as wormhole attack, which is our focus in this paper. Various solutions are proposed for wormhole attacks in sensor networks, but only a few of them take mobility of sensor nodes into account. We propose a distributed wormhole detection scheme for mobile wireless sensor networks in which mobility of sensor nodes is utilized to estimate two network features (i.e. network node density, standard deviation in network node density) through using neighboring information in a local manner. Wormhole attack is detected via observing anomalies in the neighbor nodes' behaviors based on the estimated network features and the neighboring information. We analyze the performance of proposed scheme via simulations. The results show that our scheme achieves a detection rate up to 100% with very small false positive rate (at most 1.5%) if the system parameters are chosen accordingly. Moreover, our solution requires neither" additional hardware nor tight clock synchronization which are both costly for sensor networks.
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- 2012
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23. Generating Preset Distinguishing Sequences Using SAT
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Uraz Cengiz Türker, Hüsnü Yenigün, Canan Güniçen, Hasan Ural, Gelenbe, Erol, Lent, Ricardo, and Sakellari, Georgia
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QA075 Electronic computers. Computer science ,Sequence ,Finite-state machine ,Computer science ,Computer Science::Computational Complexity ,Computer Science::Robotics ,Computer Science::Multiagent Systems ,Set (abstract data type) ,Brute force ,QA076 Computer software ,Heuristics ,Boolean satisfiability problem ,Algorithm ,Sat problem - Abstract
The preset distinguishing sequence generation problem is converted into a SAT problem to investigate the performance of SAT solvers for generating preset distinguishing sequences. An initial set of experiments are carried out and it is shown that the heuristics of SAT solvers can perform better than brute force algorithms that are used to generate preset distinguishing sequences.
- Published
- 2011
24. Client-based CardSpace-OpenID Interoperation
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Haitham S. Al-Sinani, Chris J. Mitchell, Gelenbe, Erol, Lent, R, and Sakellari, G
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Scheme (programming language) ,business.industry ,Computer science ,Faculty of Science\Mathematics ,Interoperability ,Research Groups and Centres\Information Security\ Information Security Group ,Security token ,Computer security ,computer.software_genre ,Identity management ,Interoperation ,Identity provider ,Identity (object-oriented programming) ,business ,OpenID ,computer ,Computer network ,computer.programming_language - Abstract
We propose a novel scheme to provide interoperability between two of the most widely discussed identity management systems, namely CardSpace and OpenID. In this scheme, CardSpace users are able to obtain an assertion token from an OpenID-enabled identity provider, the contents of which can be processed by a CardSpace-enabled relying party. The scheme, based on a browser extension, is transparent to OpenID providers and to the CardSpace identity selector, and only requires minor changes to the operation of the CardSpace relying party.
- Published
- 2011
25. Modal logics are coalgebraic
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Yde Venema, Lutz Schröder, Corina Cîrstea, Alexander Kurz, Dirk Pattinson, Logic and Computation (ILLC, FNWI/FGw), ILLC (FNWI), Sassone, Vladimiro, Abramsky, Samson, and Gelenbe, Erol
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Theoretical computer science ,General Computer Science ,Knowledge representation and reasoning ,Semantics (computer science) ,Computer science ,Principle of compositionality ,Programming language ,Concurrency ,Modal logic ,computer.software_genre ,Rotation formalisms in three dimensions ,Modal ,Accessibility relation ,computer - Abstract
Applications of modal logics are abundant in computer science, and a large number of structurally different modal logics have been successfully employed in a diverse spectrum of application contexts. Coalgebraic semantics, on the other hand, provides a uniform and encompassing view on the large variety of specific logics used in particular domains. The coalgebraic approach is generic and compositional: tools and techniques simultaneously apply to a large class of application areas and can, moreover, be combined in a modular way. In particular, this facilitates a pick-and-choose approach to domain-specific formalisms, applicable across the entire scope of application areas, leading to generic software tools that are easier to design, to implement and to maintain. This paper substantiates the authors’ firm belief that the systematic exploitation of the coalgebraic nature of modal logic will not only have impact on the field of modal logic itself but also lead to significant progress in a number of areas within computer science, such as knowledge representation and concurrency/mobility.
- Published
- 2011
26. Dependence analysis for regression test suite selection and augmentation
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Hasan Ural, Hüsnü Yenigün, Gelenbe, Erol, Lent, Ricardo, Sakellari, Georgia, Sacan, Ahmet, Toroslu, Hakkı, and Yazıcı, Adnan
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Set (abstract data type) ,QA075 Electronic computers. Computer science ,Test case ,System under test ,Computer science ,Suite ,Extended finite-state machine ,Regression testing ,QA076 Computer software ,Test suite ,Dependence analysis ,Algorithm - Abstract
Using dependence analysis for model-based regression test suite (RTS) selection and augmentation from Extended Finite State Machine (EFSM) representations of system requirements is proposed. Given an EFSM representing the requirements of a system under test (SUT) and a set of modifications (i.e., adding, deleting, and changing transitions) on the EFSM, dependencies between transitions in the EFSM are identified. These dependencies capture the effects of the model on the modifications, the effects of the modifications on the model, and the side-effects of the modifications. The proposed method selects and augments a subset of a given test suite to form an RTS by examining dependencies covered by test cases in the given test suite.
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- 2010
- Full Text
- View/download PDF
27. Developing a Scoring Function for NMR Structure-based Assignments using Machine Learning
- Author
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Bülent Çatay, Hakan Erdogan, Bruce R. Donald, Mehmet Cagri Calpur, Mehmet Serkan Apaydin, Gelenbe, Erol, Lent, Ricardo, Sakellari, Georgia, Sacan, Ahmet, Toroslu, Hakkı, and Yazıcı, Adnan
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Binary integer programming ,Boosting (machine learning) ,Computer science ,business.industry ,Chemical shift ,Residual ,Machine learning ,computer.software_genre ,Nmr data ,Support vector machine ,Residual dipolar coupling ,Structure based ,Artificial intelligence ,business ,computer - Abstract
Nuclear Magnetic Resonance (NMR1) spectroscopy involves the interaction of certain atoms which possess spin property and which are exposed to a combination of a static magnetic field and a second oscillating magnetic field. Determining the assignment of signals received from the experiments (peaks) to specific nuclei of the target molecule in NMR spectroscopy is an important challenge. Nuclear Vector Replacement (NVR) ([2, 3]) is a framework for structure-based assignments which combines multiple types of NMR data such as chemical shifts, residual dipolar couplings, and NOEs. NVR-BIP is a tool which utilizes NVR's data types as well as a scoring function with a binary integer programming (BIP) model to pair NMR peaks and amino acids for protein structure determination. The scoring function of NVR-BIP consists of 7 terms, which are added to obtain the combined score. In this paper, support vector machines (SVM) and boosting are employed to combine the terms in NVR-BIP's scoring function by viewing the assignment as a classification problem. Each peak-residue combination has a ("correct" or "incorrect") label that is predicted and the classification "score" is used as the scoring function for NVR-BIP. The assignment accuracies obtained using this approach show that boosting improves the assignment accuracy of NVR-BIP on our data set when RDCs are not available and outperforms SVMs. With RDCs, boosting and SVMs offer mixed results.
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- 2010
28. PEPA Nets
- Author
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Leïla Kloul, Stephen Gilmore, Jane Hillston, Parallélisme, Réseaux, Systèmes, Modélisation (PRISM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), M. C. Calzarossa & E. Gelenbe, Moudenner Cohen, Isabelle, Calzarossa, Maria Carla, and Gelenbe, Erol
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[INFO.INFO-PF]Computer Science [cs]/Performance [cs.PF] ,Computer science ,[INFO.INFO-PF] Computer Science [cs]/Performance [cs.PF] - Abstract
In this chapter we describe a formalism which uses the stochastic process algebra PEPA as the inscription language for labelled stochastic Petri nets. Viewed in another way, the net is used to provide a structure for linking related PEPA systems. The combined modelling language naturally represents such applications as mobile code systems where the PEPA terms are used to model the program code which moves between network hosts (the places in the net). We demonstrate the modelling capabilities of the formalism on a number of examples, including a mobile server running MobileIP.
- Published
- 2004
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