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Complex Systems and Control


Staff, Academics

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Workshop on:  “Complex Systems and Control ”

21-22 July 2016, City University

Systems & Control Research Centre

School of Mathematics, Computer Science & Engineering, City University London

Complex Systems emerge in many disciplines and domains and have many interpretations and problems associated with them. The specific domain provides dominant features and characterise the nature of problems to be considered. A major classification of such systems are to those linked with physical processes (physics, biology, genetics etc) and those which are man-made (engineering, technology, economics, management, social etc) and deal with decision making and working out solutions to complex problems. Expectations feedback and adaptive behaviour through learning are key ingredients distinguishing socio-economic systems from complex systems in engineering and the natural sciences. In economics the “system components can think”, they learn from experience and adapt their behaviour accordingly. The individual elements of a system are influenced directly by the behavior of the system as a whole, and at the same time their interactions lead to the emergent behaviour at the aggregate level of the system. Such systems emerge in engineering, economics, finance and management which define a range of high complexity problems, requiring fundamentally new thinking and address complexity with an interdisciplinary approach beyond the current approaches. The workshop aims to address the challenges and explore the possibilities of developing fundamental research by bringing together expertise from many and diverse areas for such systems and stimulate the formulation of ideas leading to new research.


Thursday 21st July (Room D104)

9.00-9.15: Welcome, Coffee, Registration

9.15-9.25:  Introduction: Nicos Karcanias

Systems & Control Centre, City University

“Complex Systems and Challenges”

Chairman (Morning Session):  George Halikias

9.25-10.00: Presentation (1): Sarah Spurgeon

School of Engineering and Digital Arts, Canterbury,

“Modelling of Psoriasis Pathogenesis: A Control Systems Perspective”

10.00-10.35 : Presentation (2): Markos Papageorgiou,

Dynamic Systems & Simulation Lab., Techn. Univ. of Crete,

“Complex System Problems in Road Traffic Control”

10.35-11.10:  Presentation (3):  George Papavasilopoulos:

Dept.of Electrical &Computer Engineering,National Technical University of Athens,

“Nash Games with Random Entrance and Duration, Overlapping  Generation, Players in a Network: Stability Gains, Design for Fast Convergence”

11.10-11.20: Coffee Break

11.20-11.55:  Presentation (4): Malcolm Smith

Engineering Department, Univesrity of Cambridge,

“Reciprocity, Passivity and Optimal Control”

11.55-12.30: Presentation (5): Emmanuel Pothos

Department of Psychology, City University,

‘Quantum models of decision making’

12.30-13.05: Presentation: (6) George Halikias:

Systems & Control Centre, City University,

“The Quadratic Integer Programming problem: Relaxations and Extensions”

13.05-13.15:  Discussion

13.15-14.15:  Lunch Break

Chairman (Afternoon Session): Nicos Karcanias

14.15-14.50: Presentation (7): Lefteris Tsoukalas:

Nuclear Engineering Lab, University of Purdue,

"Smart Energy Connectivity"

14.50-15.25:  Presentation (8): David Stupples :

Systems and Control Centre, City University,

Electronic Warfare - A system of systems perspective"

15.25-16.00: Presentation (9): Eduardo Alonso

Systems and Control Centre, City University,

“Emergent Systems of Systems”

16.00-16.15: Coffee, Tea Break

16.15-16.50: Presentation (10): Raj Muttukrishnan

Electrical Engineering, City University,

“Graph based intrusion detection for large complex networks”

17.25-17.55: Discussion on possible research initiatives

17.55-18.00: Conclusions

Friday, 22 July (Room D104)

9.00-9.15: Coffee, Registration

Chairman (Morning Session):  Nicos Karcanias

9.15-9.50 :  Presentation (1):Antonis Alexandridis & Panos Papageorgiou

University of Patras, Power Systems Lab, Greece,

“Modern power systems analysis and management via a complex network implementation“

9.50-10.25:  Presentation (2):Alexandra Brintrup

Engineering Department, Univesrity of Cambridge,

“Detangling complex production networks: the role of digital manufacturing”

10.25-11.00: Presentation (3): Nicos Karcanias:

Systems & Control Centre , City University,

"Systems Complexity, Reengineering and System of Systems"

11.00-11.15 : Coffee Break

11.15-11.50: Presentation (4): Eric Rogers

Dept. of Electron. & Computer Science, Univ. of Southampton,

“Complexity Issues in Robotic-assisted Next Generation Stroke Rehabilitation

11.50-12.25: Presentation (5): Demetra Evangelou:

Democritus University of Thrace, Greece,

"Developmental Engineering and the Pedagogy of Artifacts"

12.25-13.00: Presentation (6): Tom Chen:

Systems & Control Centre, City University,

“Sony Pictures Intrusion and Coercion Theory”

13.00-14.00: Lunch Break

Chairman (Afternoon Session): Ali Hessami

14.00-14.35: Presentation (7) Stathis Kasderidis

NOVOCAPTIS, Thessaloniki, Greece,

"Increasing product complexity requires a new testing and validation methodology".

14.35-15.10:  Presentation (8) Giorgos Galanis :

Goldsmiths, Univ.of London and New Economics Foundation,

“A stock-flow-fund ecological macroeconomic model “

15.10-15.25 : Coffee, Tea Break

15.25-16.00: Presentation (9): Ali Hessami:

Vega Systems, LU and Systems and Control Centre

“System of Systems: A Quantitative Chracterisation Framework”

16.00-16.35: Presentation (10):  Slawomir Nasuto

Univ of Reading,

“Systems approach to study ‘states’ of mesoscopic neural networks”

16.35-17.10: Presentation (11):  Mahdi Ramezanalagheband

Azad University Iran,

“Cryptography Algorithms in CryptDB”

17.10-17.40: Discussion on possible research initiatives

17.40-17.45: Conclusions


Sarah Spurgeon

School of Engineering and Digital Arts, Canterbury,

“Modelling of Psoriasis Pathogenesis: A Control Systems Perspective”

Abstract: Psoriasis is a dynamic, chronic inammatory skin disease characterized by the presence of well-demarcated regions of red, thickened skin with silvery scales known as psoriatic plaques. The pathogenesis of psoriasis is known to involve a complex signaling network of interactions between cytokines, immune cells and keratinocytes. The keratinocytes make up cells of the epidermis (the most superficial cell layer comprising the skin). In psoriasis keratinocytes proliferate more rapidly and have abnormal differentiation resulting in plaques, however, the mechanisms of emergence of psoriatic plaques in the cytokine-immune cell network remain unclear.

This presentation will discuss a new systems model of psoriasis. The model is analysed from the perspective of control theory. Cytokines are treated as actuators to the plant model that govern the cell population under the reasonable assumption that cytokine dynamics are faster than the cell population dynamics. The analysis of various equilibria is undertaken based on singular perturbation theory. Finite time stability and stabilisation has been studied in various engineering applications where the principal paradigm uses non-Lipschitz functions of the states. A comprehensive study of the finite time stability properties of the proposed psoriasis dynamics is carried out. It is demonstrated that the dynamics are finite time convergent to certain equilibrium points rather than asymptotically or exponentially convergent. This feature of _nite time convergence motivates the development of a modi_ed version of the Michaelis-Menten function, frequently used in biology. This framework is used to model cytokines as fast finite time actuators and has the potential to provide new insights into how to exploit the role of cytokines in future treatments for psoriasis.

Markos Papageorgiou

Dynamic Systems & Simulation Laboratory,  Technical University of Crete

“Complex System Problems in Road Traffic Control”

Abstract: A prevalent type of complex systems is composed or perceived as consisting of a high number of smaller interacting subsystems. When attempting to influence (control) the behaviour of such a complex system, it is often of importance to control individual subsystems in a distributed way, so as to achieve an emergent desired overall complex system behaviour. Related problems have been addressed in the last decades under several disciplines or brand names, such as decentralised control, artificial life bottom-up approaches, multi-agent systems, autonomic systems, systems of systems. Despite some limited successful developments, a general theory for this type of complex system control is still lacking, while potential application domains are appearing increasingly. Insights from successful applications may contribute towards a general theory.

Several modern transportation problems belong to this class of complex systems, and the presentation will outline some few of those. Specifically:

  • Motorway networks may be perceived as comprising a number of bottleneck locations to be controlled in a distributed way.
  • Urban road networks may be perceived as consisting of a number of signalised junctions to be controlled individually.
  • Traffic and, in particular, future traffic with automated vehicles may be perceived as the outcome of individual behaviours of thousands of involved vehicles.

Issues related to difficulties, opportunities, system architecture and available results will be highlighted.

George.P. Papavassilopoulos

Dept.of Electrical &Computer Engineering,National Technical University of Athens

“Nash Games with Random Entrance and Duration , Overlapping  Generation, Players in a Network: Stability Gains,Design for Fast Convergence”

Abstract: We present two topics of current research, both addressing Nash dynamic games. In the first we consider an LQ game with many randomly entering players who stay in the game for a random period of rime. At each time step a random number of players enters the game and each one of them has a random time horizon. Examples of such interaction patterns appear is several situations such as the customers of a bank, the electricity producing firms and intergeneration cooperation and competition. The Nash equilibrium is characterized by coupled Riccati equations for Markovian Jump Linear Systems. We also consider the game with a very large number of players assuming a Kantian cooperative behavior. We focus on the effects of the distribution of the number of the players entering the game at each time step, as well as the probability of leaving the game at each time step on the stability of the overall system, as well as the cost and the gains of the participants. Several numerical results are also presented.

In the second part we consider a Network with players located at its vertices, each one interacting with its neighbors in a repeated Nash game. We focus on the problem of designing the Network so that the set of dynamic rules converges quickly to the Nash equilibrium. Particularly a very simple class of repeated games with mean field interactions is considered and we assume that the actions of the participants are determined using some simple myopic gradient based dynamic rules. The information about the actions of the other players is transmitted through the Network, using a consensus type dynamics. The speed of the convergence to equilibrium is characterized, using the Lyapunov equation involving a Laplacian like matrix. A topology optimization problem for the communication graph is then stated and an algorithm, based on the effects of new edges to the speed of convergence, is proposed. Numerical results are also given.

Malcolm C. Smith

Engineering Department, University of Cambridge,

“Reciprocity, Passivity and Optimal Control”

Abstract: The talk will explore the classical notion of reciprocity in physics and network theory.  Standard proofs of the reciprocity property in electrical circuits will be explained and a recent treatment of Jan Willems highlighted.  The talk then moves to mechanical networks where the analogous property will be explored.  Reciprocity will be shown to impose a restriction in the ride-handling compromise in vehicle dynamics.  The talk then considers a nonlinear optimal control problem arising in semi-active vehicle suspensions in which the ride-handling compromise is modelled with stochastic disturbance inputs for ride performance and deterministic disturbances for handling inputs.  Experimental results implemented on a high-performance sports car using the proposed approach will be presented. The talk will conclude with some remarks on reciprocity in relation to this application.

Emmanuel Pothos

Department of Psychology, City University,

‘Quantum models of decision making’

Abstract: Quantum cognition refers to the research programme of trying to build cognitive models using (some of) the principles for probabilistic inference from quantum theory. Quantum cognitive models recommend themselves in cases where human behaviour appears at odds with the prescription of classical/ Bayesian theory. For example, there have been numerous demonstrations of violations of the law of total probability in simple decision situations. Such demonstrations have been associated with the influential Tversky (one of the most cited psychologists of all time), Kahneman (Nobel prize for economics, for Prospect Theory, which he developed with Tversky) tradition. A violation of the law of total probability might indicate the presence of interference effects, analogous to the one that sometimes appear when considering incompatible observables in physics. How can such ideas lead to the development of cognitive models? What is the meaning of incompatibility in cognition? This is a particularly challenging question, since the quantum cognition research programme assumes a classical brain. So, how can incompatibility emerge at the cognitive level, from a fully classical neural substrate? Finally, how do quantum cognitive models compare to alternative, matched models and what is the generative value of quantum cognitive models? My introduction of the quantum cognition research programme will aim to consider these questions and outline the current key challenges in this exciting, inter-disciplinary research direction for the mathematics of quantum theory.

George Halikias

Systems and Control Centre, SMCSE, City University,

“The Quadratic Integer Programming problem: Relaxations and Extensions”

Abstract: The Quadratic Integer Programming (QIP) problem is a classical computationally intractable (NP-hard) problem which has numerous applications in Control, OR, Statistics (minimum-trace factor analysis) and graph theory ("max-cut" problem). Various relaxation methods of the problem are reviewed. A novel technique is described which explores the properties of the optimal solution of the dual problem in order to reduce the duality gap. This is achieved by solving an auxiliary problem of the same form as the primal (QIP) but of reduced rank. Using a technique by Avis and Fukuda, the solution to this problem can be derived by enumerating the vertices of a zonotope in a low-dimensional space, which can be performed in polynomial-time. Some interesting extensions of this approach are described with applications in robust control.

Lefteris Tsoukalas

Nuclear Engineerig Lab, University of Purdue, USA,

"Smart Energy Connectivity"

Abstract: Energy diversification and efficiency drives a worldwide innovation effort popularly known as the pursuit of smart energy. At the core of this effort we find the transformative potential of energy connectivity, that is, the successful convergence of energy, computing and information technologies.  We will discuss how the promise of smart energy may revolutionize electricity generation, transport and distribution. Pricing signals and short-term elasticities can optimize power distribution and maintain the delicate equilibrium involved in evolving power systems within the smart energy framework.  Intelligent approaches form the cornerstone of an energy internet enhancing a variety of network functionalities including, but not limited to, forecasting, monitoring and control at multiple levels.

David Stupples

Systems and Control Centre, City University,

"Electronic Warfare - A system of systems perspective"

Abstract: Electronic warfare in the 21st Century now covers the electromagnetic spectrum, cyber space and physiological operations orchestrated to bring chaos to a nation country. This presentation will explain how a chaotic state can be orchestrated and how the elements of electronic warfare are systematically integrated to maximum effect. A case study will be presented focusing on Russian activity in the Ukraine.

Eduardo Alonso

Systems and Control Centre, City University,

“Emergent Systems of Systems”

Abstract: We will present a first attempt to formalise Systems of Systems based on game theory and Multi-Agent Systems. We propose to use control agents to enforce joint strategies, which solve problems arising from the unconstrained interaction of autonomous agents and where Nash equilibria are suboptimal. In essence, in the resulting systems new solutions emerge, forming Systems of Systems that can form hierarchies.

Raj Muttukrishnan

Electrical Engineering, City University,

Graph based intrusion detection for large complex networks”

Abstract: For a security analyst, determining whether a network asset has been compromised by or vulnerable to an attack is an important task. The process of accomplishing this task however is often tedious and involves studying the activities of network hosts and manually piecing together evidence collected from a range of security devices. Although many correlation frameworks exist, many rely on pre-domain knowledge. This presentation will introduce a new framework for observing and capturing complex network  behaviour by analysing Intrusion detection logs to detect progressive attacks in complex networks.

Antonio Alexandridis & Panos Papageorgiou

Department of Electrical and Computer Engineering, University of Patras, Rion Patras, 26500,

Modern power systems analysis and management via a complex network implementation“

Abstract: Modern power systems structure has been dramatically changed in last decades mainly due to environmental reasons and the climate change. The wide penetration of renewable generation is the basic new characteristic, with the wind power system generation and the photovoltaic energy production continuously increased. Nevertheless, since now, the electric energy production is dispersed near the distribution grid, the nature of the power consumption changes from the passive to active loads. New local distribution structures, known as microgrids, are already in operation while advanced information technologies are incorporated in a manner that leads to smart grid deployments. Energy storage devices, with the electric vehicles to play a key role, are proposed while power demand is a main point of managing the distributed generation. Additionally, significant incentives are provided to the customers in order to have economic benefits by agreeing to consume energy in off-peak hours. As a result novel energy planning strategies and power management policies should be applied. In this frame, a new, more efficient tool for the power system analysis that takes into account all the above innovations is a necessary demand. An implementation based on complex network may be an effective solution.

Alexandra Brintrup

Engineering Department, Univesrity of Cambridge,

“Detangling complex production networks: the role of digital manufacturing”.

Abstract: Production networks emerge as companies procure goods from each other; simultaneously creating value and risk. It has been shown that such networks contain hidden patterns that have implications on the robustness and performance of manufacturers embedded within the network. The rise of digital manufacturing technologies such as the Internet of Things is creating new, large-scale data streams that now make the mining of these patterns possible. In this talk, we shall discuss how such technologies can uncover  systemic viewpoints, and give case examples from the automotive and aerospace sectors. We will conclude by proposing a research agenda for the use of digital manufacturing technologies to understand and improve system dependencies.

Nicos Karcanias

Systems & Control Centre, City University,

"Systems Complexity, Re-engineering and System of Systems"

Abstract: Complex Systems is a term that emerges in many disciplines and domains and has many interpretations, implications and problems associated with it. A major classification of such systems are to those linked with physical processes (physics, biology, genetics, ecosystems, social etc) and those which are man made (engineering, technology, energy, transport, software, management and finance etc) and deal with the “macro level” issues and technology. Management of complexity is a major problem in science and technology. We focus on the study of complexity by examining the problem of Re-engineering of Large Infrastructure Systems (LIS). We focusour investigation on examining the complexityissues linked to the re-engineering of LIS, and propose the development of a research framework that may enable the management of systems complexity. The major challenges we need to address from the systems viewpoint are linked to:

Ÿcouplings between physical, information layers, operational functions, and emergent properties

ŸExamining methods for measuring systems connectivity

ŸClarifying the role of Systems of Systems (SoS) within the re-engineering problem.

ŸInvestigating possible methods for reducing systems complexity

The notion of “System of Systems” (SoS)has emerged in many fields of applications. Such systems introduce a new systems paradigm with main characteristic the interaction of many independent, autonomous systems, frequently of large dimensions, which are brought together in order to satisfy a global goal and under certain rules of engagement. They represent a synthesis of systems which themselves have a degree of autonomy, where the interconnection topology evolves to a rule represented by the new notion of a “systems play”. The presented framework for the management of LIS complexity requires understanding system connectivity, the role of SoS and exploring the potential of the Holonic System Architecture that enables the introduction of autonomy and cooperation between subsystems. We advocate that the development of such a research framework will enable the future development of a systematic method for re-engineering of LIS that will enable “re-architecturing” of the physical, information and operational layer of the system

Eric Rogers

Dept of Electronics and Computer Science, Univ. of Southampton

“Complexity Issues in Robotic-assisted Next Generation Stroke Rehabilitation”

Abstract: The consequences of stroke are increasing at a very significant rate where a very significant driver is an ageing population in many countries. Also it is recognised that re-learning lost functionality required is high intensity repetition of a task. Moreover, the currently available rehabilitation is poor in relative terms, especially outside the hospital environment, and there is a pressing need for improved quality rehabilitation for home use. In this domain, supporting rehabilitation by technology underpinned by appropriately designed control interventions which aid individuals to perform rehabilitation tasks and exercises can reduce the costs to healthcare providers and optimise the intensity of therapy is a current research topic.  The variable nature of fatigue and the highly uncertain degeneration of patients suffering from neurological diseases must be accommodated. Future challenges for control engineering in this domain are aligned with the research and innovation challenges in the domain of human cyber-physical system interaction and human in the loop control design. This contribution will review progress on overcoming the complexity issues that arise and discuss ongoing and future research challenges.

Demetra Evangelou

Democritus University of Thrace, Greece,

"Developmental Engineering and the Pedagogy of Artifacts"

Abstract: The systematic study and understanding of the fundamental ontogenic nature of the relation between humans and machines-artifacts has implications for complex systems analysis and man-machine relations. Drawing on developmental theories, educational and instructional research and K-12 empirical observations, it is established that humans from very early on recognize human-made artifacts as different and qualitatively distinct from objects created by nature. Artifacts comprise a distinct class of events that create, foster, elicit and motivate humans in a manner that is different from the relationships that humans form in other contexts. They form the foundation of a pedagogy of artifacts.  In an era that integrates technology with the humanities, scientific thinking with literature, gadgetry with art, and infrastructure with economic and social thinking, developmental engineering has potential to contribute to systems approaches. During the last couple decades, the end of the Cold War and the massive relocation of manufacturing and to a lesser but significant degree engineering design in emerging markets has led to a precipitous decline in demand for engineering positions in the developed world as well as reduced interest for Engineering Education amongst the young.  Grand challenges in energy, environmental conditions, inclusive development, sustainable economies, will require, according to some estimates, 3/4ths of the workforce of the 21st Century to have post-secondary education especially in the Science Technology Engineering and Mathematics (STEM) fields. Their solution calls for the full participation of engineering talent eminently educated in state of the art pedagogy of artifacts.

Tom Chen

Systems & Control Centre, City University,

“Sony Pictures Intrusion and Coercion Theory”

Abstract: This talk will examine the November 2014 intrusion into Sony Pictures Entertainment’s computer network and subsequent terrorism threat leading up to cancellation of the film “The Interview”. We hypothesize that this intrusion might lead to a new type of terrorism threat using coercion (instead of direct physical damage). If true, we seek to understand understand and model this type of threat using coercion theory (aka compellence theory) proposed by Nobel laureate economist Thomas Schelling and others.

Stathis Kesderidis

NOVOCAPTIS, Thessaloniki, Greece,

"Increasing product complexity requires a new testing and validation methodology".

Abstract: As products in 21st century become increasingly complex traditional methodologies, on product quality assurance and validation, are not covering well products that exhibit multiple non-trivial interactions of components, scales of operation, component autonomy and time scales. For example for complex socio-technical systems, such as the Internet, there is not in the literature an established methodology which can be used to verify that as a whole it works as expected in any given day. Thus the design for the next generation of complex products and systems, such as smart cities, autonomous robotic factories, autonomous cars, etc, is hindered by the lack of an established, generic, design methodology and corresponding validation and testing (sub)-methodology.The presentation will deal with challenges, appearing in the design and validation of complex products, so as to provide a starting point of discussion between the product designer and the research community on how to best develop such a testing methodology. A brief overview of currently used methodologies, on various fields of engineering, will be given in order to provide the context for contemporary practice and to contrast it with what needs to be achieved."

George Galanis

Goldsmiths, University of London and New Economics Foundation,

A stock-flow-fund ecological macroeconomic model “

Abstract: This paper develops a stock-flow-fund ecological macroeconomic model that combines the stock-flow consistent approach of Godley and Lavoie with the flow-fund model of Georgescu-Roegen. The model has the following key features. First, monetary and physical stocks and flows are explicitly formalised taking into account the accounting principles and the laws of thermodynamics. Second, Georgescu-Roegen’s distinction between stock-flow and fund-service resources is adopted. Third, output is demand- determined but supply constraints might arise either due to environmental damages or due to the exhaustion of natural resources. Fourth, climate change influences directly the components of aggregate demand. Fifth, finance affects macroeconomic activity and the materialisation of investment plans that determine ecological efficiency. The model is calibrated using global data. Simulations are conducted to investigate the trajectories of key environmental, macroeconomic and financial variables under (i) different assumptions about the sensitivity of economic activity to the leverage ratio of firms and (ii) different types of green finance policies.

Ali Hessami

Vega Systems, LU & Systems and Control Centre,

“System of Systems: A Quantitative Chracterisation Framework”

Abstract: The objective of this talk is to explore the current notions of systems and “System of Systems” and establish the case for quantitative characterization of their structural, behavioural and contextual facets that will pave the way for further formal development (mathematical formulation). This is partly driven by stakeholder needs and perspectives and also in response to the necessity to attribute and communicate the properties of a system more succinctly, meaningfully and efficiently. The systematic quantitative characterization framework proposed will endeavor to extend the notion of emergence that allows the definition of appropriate metrics in the context of a number of systems ontologies. The general characteristic and information content of the ontologies relevant to system and system of system will be specified but not developed at this stage. The current supra-system, system and sub-system hierarchy is also explored for the formalisation of a standard notation in order to depict a relative scale and order and avoid the seemingly arbitrary attributions.

Slawomir J Nasuto

University of Reading,

"Systems approach to study ‘states’ of mesoscopic neural networks”

Abstract: The mesoscopic cortical cultured networks bridge the gap between low level neuronal properties and system-level behaviour. They are dependent on properties of single neurons, synapse types and connectivity patterns. At the same time the activity patterns emerging due to mesoscopic level interactions shape the entire brain dynamics. Animats, hybrid systems consisting of robotic bodies controlled in a closed loop by mesoscopic neuronal cultures, offer an attractive platform linking the activity of such networks to behaviour. The potential applications include autonomous robotics and development of novel therapeutics for neurological disorders.

We studied the spontaneous development of mesoscopic cultures of rat cortical neurons using complex networks approaches. Functional connectivity analysis revealed that cultures start with a random pattern of interactions which nevertheless develop small world characteristic as cultures mature. Models of connectivity evolution reveal that the burst networks are not completely random, although they do not show temporal dependencies. The animat platform makes it possible to investigate the effects of closed loop interactions on such neurobiological, dynamical and complex networks properties. It will also help to elucidate the functional role of the repertoire of complex systems characteristics. Recent work though offers a word of caution pointing to the limits of such investigations prompting a need for more robust complex systems tools capable of unravelling variables playing causal roles in network function.

Mahdi Ramezanalagheband

Azad University Iran,

“Cryptography Algorithms in CryptDB”

Abstract: Online services are vulnerable to reveal sensitive information because adversaries can embed some backdoors to gain access to private data, and malicious administrators might manipulate stored data. Although the encryption of stored data in the cloud can reduce security and privacy risks, this usually implies incapable of functionality. Popa and her team at MIT first proposed their CryptDB method to alleviate the problems. CryptDB is a practical framework to keep confidentiality against insider/outsider attacks. CryptDB applies varied cryptographic schemes, such as non-deterministic, order-preserving, hemimorphic, searchable, into onion shaped layers be able search encrypted data. Hence it supports basic functions: Addition, multiplication, greater than, equality, search, and nesting these functions. As a result, an administrator never gets access to decrypted data, and even if all servers are compromised, an adversary cannot decrypt the data of any user A few companies used or adopted CryptDB, or were inspired by CryptDB including Google, Microsoft, Skyhigh, etc. In this presentation, we review CryptDB system and look through the encryption methods in CryptDB and compare it with other solutions.

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When & where

From Thursday 21st July 2016 to Friday 22nd July 2016

D104 Social Sciences Building City, University of London St John Street London EC1R 0JD United Kingdom