Biblio

In recent years, due to the invasion of virus and loopholes, computer networks in colleges and universities have caused great adverse effects on schools, teachers and students. In order to improve the accuracy of computer network security evaluation, Back Propagation (BP) neural network was trained and built. The evaluation index and target expectations have been determined based on the expert system, with 15 secondary evaluation index values taken as input layer parameters, and the computer network security evaluation level values taken as output layer parameter. All data were divided into learning sample sets and forecasting sample sets. The results showed that the designed BP neural network exhibited a fast convergence speed and the system error was 0.000999654. Furthermore, the predictive values of the network were in good agreement with the experimental results, and the correlation coefficient was 0.98723. These results indicated that the network had an excellent training accuracy and generalization ability, which effectively reflected the performance of the system for the computer network security evaluation.

Major blackouts are due to cascading failures in power systems. These failures usually occur at vulnerable links of the network. To identify these, indicators have already been defined using complex network theory. However, most of these indicators only depend on the topology of the grid; they fail to detect the weak links. We introduce a new metric to identify the vulnerable lines, based on the load-flow equations and the grid geometry. Contrary to the topological indicators, ours is built from the electrical equations and considers the location and magnitude of the loads and of the power generators. We apply this new metric to the IEEE 118-bus system and compare its prediction of weak links to the ones given by an industrial software. The agreement is very well and shows that using our indicator a simple examination of the network and its generator and load distribution suffices to find the weak lines.

The aim of this paper is to explore the performance of two well-known wave energy converters (WECs) namely Floating Buoy Point Absorber (FBPA) and Oscillating Surge (OS) in onshore and offshore locations. To achieve clean energy targets by reducing greenhouse gas emissions, integration of renewable energy resources is continuously increasing all around the world. In addition to widespread renewable energy source such as wind and solar photovoltaic (PV), wave energy extracted from ocean is becoming more tangible day by day. In the literature, a number of WEC devices are reported. However, further investigations are still needed to better understand the behaviors of FBPA WEC and OS WEC under irregular wave conditions in onshore and offshore locations. Note that being surrounded by Bay of Bengal, Bangladesh has huge scope of utilizing wave power. To this end, FBPA WEC and OS WEC are simulated using the typical onshore and offshore wave height and wave period of the coastal area of Bangladesh. Afterwards, performances of the aforementioned two WECs are compared by analyzing their power output.

Linear oscillating actuators are emerging electrical motors applied to direct-drive electromechanical systems. They merit high efficiency and quick dynamical property due to the unique structure of spring oscillator. Resonant principle is the base of their high performance, which however, is easily influenced by various load, complex environment and mechanical failure. This paper studies the modeling of linear oscillating actuators in multi-work condition. Three kinds of load are considered in performance evaluation model. Simulations are conducted at different frequencies to obtain the actuator behavior, especially at non-resonance frequencies. A method of constant impedance angle is proposed to search the best working points in sorts of conditions. Eventually, analytical results reflect that the resonant parameter would drift with load, while linear oscillating actuators exhibits robustness in efficiency performance. Several evaluating parameters are concluded to assess the actuator health status.

The NEREIDA wave generation power plant installed in Mutriku, Spain is a multiple Oscillating Water Column (OWC) plant. The power takeoff consists of a Wells turbine coupled to a Doubly Fed Induction Generator (DFIG). The stalling behavior present in the Wells turbine limits the generated power. This paper presents the modeling and a Harmony Search Algorithm-based airflow control of the OWC. The Harmony Search Algorithm (HSA) is proposed to help overcome the limitations of a traditionally tuned PID. An investigation between HSA-tuned controller and the traditionally tuned controller has been performed. Results of the controlled and uncontrolled plant prove the effectiveness of the airflow control and the superiority of the HSA-tuned controller.

Inductive contactless energy transfer (CET) systems show a certain oscillating transient behavior of inrush currents on both system sides. This causes current overshoots in the electrical components and has to be considered for the system dimensioning. This paper presents a simple and yet very accurate model, which describes the dynamic behavior of series-series compensated inductive CET systems. This model precisely qualifies the systems current courses for both sides in time domain. Additionally, an analysis in frequency domain allows further knowledge for parameter estimation. Since this model is applicable for purely resistive loads and constant voltage loads with bridge rectifiers, it is very practicable and can be useful for control techniques and narameter estimation.

Physical Unclonable Functions (PUFs) are vulnerable to various modelling attacks. The chaotic behaviour of oscillating systems can be leveraged to improve their security against these attacks. We have integrated an Arbiter PUF implemented on a FPGA with Chua's oscillator circuit to obtain robust final responses. These responses are tested against conventional Machine Learning and Deep Learning attacks for verifying security of the design. It has been found that such a design is robust with prediction accuracy of nearly 50%. Moreover, the quality of the PUF architecture is evaluated for uniformity and uniqueness metrics and Monte Carlo analysis at varying temperatures is performed for determining reliability.

This article is dedicated to the study of an innovative architecture for the conversion of renewable marine energy into electrical energy. It consists of a Permanent Magnet Synchronous Generator (PMSG) combined with a three-phase Vienna rectifier. This last converter is not reversible but has the advantage of minimizing the number of active switches. This improves the operational reliability of the chain, which is necessary in the context of marine energy exploitation where access to the installations is not easy. The study focuses on the behavior analysis of electrical chain conversion, and the study of phase and neutral current according to the conduction’s states of the switches of the Vienna rectifier is being investigated. Despite the high non-linearity of this architecture, this control is made possible through to the dynamic performance and control of the maximum switching frequency of the self-oscillating controller called the Phase-Shift Self-Oscillating Current Controller (PSSOCC).

Oscillating-water-column (OWC) devices are a very important type of wave energy converters which have been extensively studied over the years. Although most designs of OWC are based on floating or fixed structures exposed above the surface level, little is known from completely submerged systems which can benefit from reduced environmental loads and a simplified structural design. The submerged type of resonant duct consists of two OWCs separated by a weir and air chamber instead of the commonly used single column. Under conditions close to resonance, water flows from the first column into the second one, resulting in a positive flow through the system from which energy can be extracted by a hydro turbine. While existing work has looked at the study of the behaviour of one OWC, this paper addresses the dynamic interaction between the two water columns including the mass transfer mechanism as well as the associated change of momentum. A numerical time-domain model is used to obtain some initial results on the performance and response of the system for different design parameters. The model is derived from 1D conservation of mass and momentum equations, including hydrodynamic effects, adiabatic air compressibility and turbine induced damping. Preliminary results indicate that the mass transfer has an important effect both on the resonance amplification and on the phase between the motion of the two columns. Simulation results are presented for the system performance over several weir heights and regular wave conditions. Further work will continue in design optimization and experimental validation of the proposed model.

Adversarial examples that fool machine learning models, particularly deep neural networks, have been a topic of intense research interest, with attacks and defenses being developed in a tight back-and-forth. Most past defenses are best effort and have been shown to be vulnerable to sophisticated attacks. Recently a set of certified defenses have been introduced, which provide guarantees of robustness to norm-bounded attacks. However these defenses either do not scale to large datasets or are limited in the types of models they can support. This paper presents the first certified defense that both scales to large networks and datasets (such as Google's Inception network for ImageNet) and applies broadly to arbitrary model types. Our defense, called PixelDP, is based on a novel connection between robustness against adversarial examples and differential privacy, a cryptographically-inspired privacy formalism, that provides a rigorous, generic, and flexible foundation for defense.

To preserve the privacy of social networks, most existing methods are applied to satisfy different anonymity models, but there are some serious problems such as huge large information losses and great structural modifications of original social network. Therefore, an improved privacy protection method called k-subgraph is proposed, which is based on k-degree anonymous graph derived from k-anonymity to keep the network structure stable. The method firstly divides network nodes into several clusters by label propagation algorithm, and then reconstructs the sub-graph by means of moving edges to achieve k-degree anonymity. Experimental results show that our k-subgraph method can not only effectively improve the defense capability against malicious attacks based on node degrees, but also maintain stability of network structure. In addition, the cost of information losses due to anonymity is minimized ideally.

Recently, Pan/Tilt/Zoom (PTZ) camera has been widely used in video surveillance systems. However, it is difficult to automatically control PTZ cameras according to moving objects in the surveillance area. This paper proposes an automatic camera control method based on a Deep-Q Network (DQN) for improving the recognition accuracy of anomaly actions in the video surveillance system. To generate PTZ camera control values, the proposed method uses the position and size information of the object which received from the video analysis system. Through implementation results, the proposed method can automatically control the PTZ camera according to moving objects.

In the last decade, the adoption of wireless systems has increased. These systems allow multiple devices to send data wirelessly using radio waves. Moreover, in some applications, authentication is done wirelessly by exchanging authentication data over the air as in wireless locks and keyless entry systems. On the other hand, most of the wireless devices today can control the radio frequency transmission power to optimize the system's performance and minimize interference. In this paper, we explore the possibility of modulating the radio frequency transmission power in wireless systems for authentication purposes and using it for source authentication. Furthermore, we propose two system models that perform authentication using variable power transmission patterns. Then, we discuss possible applications. Finally, we implement and test a prototype system using IEEE 802.11 (Wi-Fi) devices.

Software Defined Networking (SDN) is an emerging architecture providing services on a priority basis for real-time communication, by pulling out the intelligence from the hardware and developing a better management system for effective networking. Denial of service (DoS) attacks pose a significant threat to SDN, as it can disable the genuine hosts and routers by exhausting their resources. It is thus vital to provide efficient traffic management, both at the data layer and the control layer, thereby becoming more responsive to dynamic network threats such as DoS. Existing DoS prevention and mitigation models for SDN are computationally expensive and are slow to react. This paper introduces a novel biologically inspired architecture for SDN to detect DoS flooding attacks. The proposed biologically inspired architecture utilizes the concepts of the human immune system to provide a robust solution against DoS attacks in SDNs. The two layer immune inspired framework, viz innate layer and adaptive layer, is initiated at the data layer and the control layer of SDN, respectively. The proposed model is reactive and lightweight for DoS mitigation in SDNs.

As technology is developing exponentially and the world is moving towards automation, the resources have to be transferred through the internet which requires routers to connect networks and forward bundles (information). Due to the vulnerability of routers the data and resources have been hacked. The vulnerability of routers is due to minimum authentication to the network shared, some technical attacks on routers, leaking of passwords to others, single passwords. Based on the study, the solution is to maximize authentication of the router by embedding an application that monitors the user entry based on MAC address of the device, the password is frequently changed and that encrypted password is sent to a user and notifies the admin about the changes. Thus, these routers provide high-level security to the forward data through the internet.

The security problem of RFID system is a great potential security hazard in its application. Due to the limitation of hardware conditions, traditional public key cryptography can not be directly used in security mechanism. Compared with the traditional RSA public key cryptography, the elliptic curve cryptography has the advantages of shorter key, faster processing speed and smaller storage space, which is very suitable for use in the RFID system.

For complex technical objects the research of cybersecurity problems should take into account both physical and information properties of the object. The paper considers a hybrid model that unifies information and physical models and may be used as a tool for countering cyber threats and for cybersecurity risk assessment at the design and operational stage of an object's lifecycle.

The traditional electricity distribution system is rapidly shifting from the passive infrastructure to a more active infrastructure, giving rise to a smart grid. In this project an active electricity distribution network and its components have been studied. A 14-node SCADA-based active distribution network model has been proposed for managing this emerging network infrastructure to ensure reliability and protection of the network The proposed model was developed using matlab /simulink software and the fuzzy logic toolbox. Surge arresters and circuit breakers were modelled and deployed in the network at different locations for protection and isolation of fault conditions. From the reliability analysis of the proposed model, the failure rate and outage hours were reduced due to better response of the system to power fluctuations and fault conditions.

Fingerprinting the malware by its behavioural signature has been an attractive approach for malware detection due to the homogeneity of dynamic execution patterns across different variants of similar families. Although previous researches show reasonably good performance in dynamic detection using machine learning techniques on a large corpus of training set, decisions must be undertaken based upon a scarce number of observable samples in many practical defence scenarios. This paper demonstrates the effectiveness of generative adversarial autoencoder for dynamic malware detection under outbreak situations where in most cases a single sample is available for training the machine learning algorithm to detect similar samples that are in the wild.

The smart grid changes the way energy is produced and distributed. In addition both, energy and information is exchanged bidirectionally among participating parties. Therefore heterogeneous systems have to cooperate effectively in order to achieve a common high-level use case, such as smart metering for billing or demand response for load curtailment. Furthermore, a substantial amount of personal data is often needed for achieving that goal. Capturing and processing personal data in the smart grid increases customer concerns about privacy and in addition, certain statutory and operational requirements regarding privacy aware data processing and storage have to be met. An increase of privacy constraints, however, often limits the operational capabilities of the system. In this paper, we present an approach that automates the process of finding an optimal balance between privacy requirements and operational requirements in a smart grid use case and application scenario. This is achieved by formally describing use cases in an abstract model and by finding an algorithm that determines the optimum balance by forward mapping privacy and operational impacts. For this optimal balancing algorithm both, a numeric approximation and - if feasible - an analytic assessment are presented and investigated. The system is evaluated by applying the tool to a real-world use case from the University of Southern California (USC) microgrid.

Nowadays the role of Information systems in our life has greatly increased, which has become one of the biggest challenges for citizens, organizations and governments. Every single day we are becoming more and more dependent on information and communication technology (ICT). A major goal of information security is to find the best ways to mitigate the risks. The context-role and perimeter protection approaches can reduce and prevent an unauthorized penetration to protected zones and information systems inside the zones. The result of this work can be useful for the security system analysis and optimization of their organizations.

The current paper proposes a method to combine the theoretical concepts of the parallel processing created by the DNA computing and GA environments, with the effectiveness novel mechanism of the distinction and discover of the cryptosystem keys. Three-level contributions to the current work, the first is the adoption of a final key sequence mechanism by the principle of interconnected sequence parts, the second to exploit the principle of the parallel that provides GA in the search for the counter value of the sequences of the challenge to the mechanism of the discrimination, the third, the most important and broadening the breaking of the cipher, is the harmony of the principle of the parallelism that has found via the DNA computing to discover the basic encryption key. The proposed method constructs a combined set of files includes binary sequences produced from substitution of the guess attributes of the binary equations system of the cryptosystem, as well as generating files that include all the prospects of the DNA strands for all successive cipher characters, the way to process these files to be obtained from the first character file, where extract a key sequence of each sequence from mentioned file and processed with the binary sequences that mentioned the counter produced from GA. The aim of the paper is exploitation and implementation the theoretical principles of the parallelism that providing via biological environment with the new sequences recognition mechanism in the cryptanalysis.

Cooperative Intelligent Transport Systems (C-ITS) are expected to play an important role in our lives. They will improve the traffic safety and bring about a revolution on the driving experience. However, these benefits are counterbalanced by possible attacks that threaten not only the vehicle's security, but also passengers' lives. One of the most common attacks is the Sybil attack, which is even more dangerous than others because it could be the starting point of many other attacks in C-ITS. This paper proposes a distributed approach allowing the detection of Sybil attacks by using the traffic flow theory. The key idea here is that each vehicle will monitor its neighbourhood in order to detect an eventual Sybil attack. This is achieved by a comparison between the real accurate speed of the vehicle and the one estimated using the V2V communications with vehicles in the vicinity. The estimated speed is derived by using the traffic flow fundamental diagram of the road's portion where the vehicles are moving. This detection algorithm is validated through some extensive simulations conducted using the well-known NS3 network simulator with SUMO traffic simulator.

Cyber-Physical Systems (CPS) are growing with added complexity and functionality. Multidisciplinary interactions with physical systems are the major keys to CPS. However, sensors, actuators, controllers, and wireless communications are prone to attacks that compromise the system. Machine learning models have been utilized in controllers of automotive to learn, estimate, and provide the required intelligence in the control process. However, their estimation is also vulnerable to the attacks from physical or cyber domains. They have shown unreliable predictions against unknown biases resulted from the modeling. In this paper, we propose a novel control design using conditional generative adversarial networks that will enable a self-secured controller to capture the normal behavior of the control loop and the physical system, detect the anomaly, and recover from them. We experimented our novel control design on a self-secured BMS by driving a Nissan Leaf S on standard driving cycles while under various attacks. The performance of the design has been compared to the state-of-the-art; the self-secured BMS could detect the attacks with 83% accuracy and the recovery estimation error of 21% on average, which have improved by 28% and 8%, respectively.

Appending digital signatures and certificates to messages guarantee data integrity and ensure non-repudiation, but do not identify greedy authenticated nodes. Trust evolves if some reputable and trusted node verifies the node, data and evaluates the trustworthiness of the node using an accurate metric. But, even if the verifying party is a trusted centralized party, there is opacity and obscurity in computed reputation rating. The trusted party maps it with the node's identity, but how is it evaluated and what inputs derive the reputation rating remains hidden, thus concealment of transparency leads to privacy. Besides, the malevolent nodes might collude together for defamatory actions against reliable nodes, and eventually bad mouth these nodes or praise malicious nodes collaboratively. Thus, we cannot always assume the fairness of the nodes as the rating they give to any node might not be a fair one. In this paper, we propose a smart contract-based approach to update and query the reputation of nodes, stored and maintained by IPFS distributed storage. The use case particularly deals with an emergency scenario, dealing against colluding attacks. Our scheme is implemented using MATLAB simulation. The results show how smart contracts are capable of accurately identifying trustworthy nodes and record the reputation of a node transparently and immutably.