Ns3 Projects

With the rapid growth of data centers and the unprecedented increase in storage demands, the traditional storage control techniques are considered unsuitable to deal with this large volume of data in an efficient manner. The Software Defined Storage (SDStore) comes as a solution for this issue by abstracting the storage control operations from the storage devices and set it inside a centralized controller in the software layer. Building a real SDStore system without any simulation and emulation is considered an expensive solution and may have a lot of risks.

Thus, there is a need to simulate such systems before the real-life implementation and deployment. In this paper we present SDStorage, an experimental framework to provide a novel virtualized test bed environment for SDStore systems. The main idea of SDStorage is based on the Mininet Software Defined Network (SDN) Open Flow simulatorand is built over of it. The main components of Mininet, which are the host, the switch and the controller, are customized to serve the needs of SDStore simulation environments.

Two heterogeneous network simulation tools are compared and tested against measured data from terrestrial and Earth-space microwave links. Both global integrated network SIMulator (GINSIM) and MultiEXCELL are able to produce joint distributions of rain fade time-series for arbitrary networks of microwave telecommunications links. The tools are fundamentally different in that GINSIM has, as its input, time-series of composite rain rate maps produced by networks of meteorological radars and can produce time-series of joint rain fade.

MultiEXCELL uses the rain rate distribution as an input to constrain distributions of parameters of simulated rain cells. This study tests the simulators by comparing a range of annual fade statistics produced by simulation with data measured on experimental links. Link fade data were measured on two, Ka band, Earth-space links and a convergent 38 GHz terrestrial link near Chilbolton in southern England; and a further Earth-space link located in Dundee, Scotland. Both GINSIM and MultiEXCELL are shown to be able to predict joint fade distributions and diversity gain, for the satellite and terrestrial links, to useful accuracy. Differences in performance are analysed, leading to suggested development routes for both systems.

IEEE 802.11x standard widely used in wireless local area network systems is called Wi-Fi as well. In this study high gain Microstrip Antenna (MA) design is presented for 2.4 GHz WLAN application. Simulations were made on parameters such as the geometry and size of antennas, type of dielectric material, the thickness of substrate for most appropriate designing of antenna.

For simulations, HFSS software which is a full wave and finite element based simulator was used. Total maximum gain of the designed antenna were obtained as 9.06 dB.

Today’s advanced simulators facilitate thorough studies on Vehicular Ad-hoc NETworks (VANETs). However the choice of the physical layer and the mobility models in such simulators is a crucial issue that greatly impacts the results. Realistic simulation of routing protocols in VANETs is still an open question. Indeed, only a few works address routing protocols comparison performed under realistic conditions. This paper compares common reactive, pro-active, hybrid and geographic routing protocols by using a simulation platform integrating a realistic physical layer and mobility models.

It also presents and analyzes several reactive protocols enhancements propositions dedicated to the VANETs context such as multi-path routing, but also protocols tuning which allows it to adapt faster. They have all received a lot of attention and are typically proposed to increase the reliability of data transmission. This paper study the behavior of each protocol in different situations and analized their advantages and drawbacks. Results presented in this paper gives an important explanation on the contradictory results found in similar works. Finally, our realistic simulations show that reactive protocols are the best suited for VANETs, and more especially the DYMO protocol.

The electrical characteristics of the HTS power cable are dominantly dependent on the property of the HTS wire and cable geometry such as wire twist pitch, cable diameter, gap between the layers, etc. The quench occurs in HTS power cable caused by fault, the resistance appears, the current redistributed, the line impedance between the source and fault spot must be transiently changed, and mutual inductance value is directly affected.

It is very important to make sure that the protective coordination system is in real utility network. This paper presents a real time protective coordination algorithm for triad coaxial HTS power cable using symmetrical coordinate method and vector analysis under utility fault condition. The protective coordination algorithm is developed and evaluated by using the real time data acquisition system with real time digital simulator (RTDS).

Several “energy-hungry” sensors such as gas detectors, radar, and cameras have excessive energy dissipation. Virtual sensing is a technique which “breaks the downward spiral” between energy expenditure and events-miss probabilities. The idea is to deactivate main sensors and utilize a set of energy-friendly HW & SW components instead. However, reliability of such systems composed of virtual and real sensors should be as high as possible. In this article, a novel approach is proposed to improve the virtual sensing reliability. An ontology on sensor-environment relationships is utilized to automatically generate rules before deployment to switch between real and virtual sensors.

We illustrate the general approach by a case study: we show how reliable virtual sensing reduces the energy consumption and event-miss probabilities of object tracking applications. Seismic sensors and a dynamic time-warping algorithm shape the virtual object tracking sensor. We validate the precision of such virtual sensors over several experiments. A series of experiments with a network of TelosB sensor nodes show that virtual sensors have much less energy consumption than a Doppler μ-radar (main) sensor. Finally, we evaluate event-miss probabilities and lifetime extension by using the WSNetsimulator.

In railway operations, if the journey of a preceding train is disturbed, the service interval between it and the following trains may fall below the minimum line headway distance. If this occurs, train interactions will happen, which will result in extra energy usage, knock-on delays, and penalties for the operators. This paper describes a train trajectory (driving speed curve) optimization study to consider the tradeoff between reductions in train energy usage against increases in delay penalty in a delay situation with a fixed block signaling system.

The interactions between trains are considered by recalculating the behavior of the second and subsequent trains based on the performance of all trains in the network, apart from the leading train. A multitrain simulator was developed specifically for the study. Three searching methods, namely, enhanced brute force, ant colony optimization, and genetic algorithm, are implemented in order to find the optimal results quickly and efficiently. The result shows that, by using optimal train trajectories and driving styles, interactions between trains can be reduced, thereby improving performance and reducing the energy required. This also has the effect of improving safety and passenger comfort.

This paper proposes a vehicle-to-grid reactive power support (V2GQ) strategy for optimal coordinated voltage regulation in distribution networks with high distributed generation (DG) penetration. The proposed algorithm employs plug-in electric vehicles (PEVs), DG, and on-load tap changer (OLTC) to satisfy PEV charging demand and grid voltage requirements with relaxed tap operation, and minimum DG active power curtailment. The voltage regulation problem is formulated as a nonlinear programming and consists of three consecutive stages, in which successive stages apply the outputs of their preceding stages as constraints.

The first stage aims to maximize the energy delivered to PEVs to assure PEV owner satisfactions. The second stage maximizes the DG extracted active power. Third stage minimizes the voltage deviation from its nominal value utilizing the available PEV and DG reactive powers. The main implicit objective of the third stage problem is relaxing the OLTC tap operation. In addition, the conventional OLTC control is replaced by a proposed centralized controller that utilizes the output of the third stage to set its tap position. Real-time simulations are developed to demonstrate the effectiveness of the proposed optimal coordinated algorithm on a typical distribution network using OPAL-RT real-time simulator (RTS) in a hardware-in-the-loop (HIL) application.

This paper proposes an automatic voltage control method for distribution networks using distributed generators connected to the grid in order to maintain voltage levels and to provide reactive power. This method consists in exchanging information withn a two-layer hierarchical control structure. The first one is the local control, responsible for monitoring each generator operating conditions.

The second one is the central control, responsible for providing the appropriate setpoints to each local control with an algorithm based on the sensitivity theory. This method is based on a sensitivity theory that chooses the generator which will cause the major impact on the network voltage profile when changing its reactive power injection. In order to test the proposed method, the authors implemented the IEEE 13-node test feeder in the Real Time Digital Simulator at Escola Politecnica da Universidade de Sao Paulo – Brazil.

This paper presents a new proposed infrastructure that enables simultaneous cyber security and operational security. The basis of the method is command interception and fast authentication from the cyber security point of view (reliable detection of cyber intrusions) and from the operational reliability point of view. To simplify the process, the command authentication is done at the relay level and relay controls. As such it does not depend on the communication architecture. The method is based on new developments on dynamic state estimation based protection and substation level distributed state estimation. This infrastructure provides the capability to monitor, intercept, and authenticate/block commands as they reach the relay and the control circuits of the relay. Since all controls are exercise through a relay, this approach provides 100% coverage.

The authentication/blockage of commands is done quickly because of the distributed approach which enables quick assembly of a local real time model and fast analytics with this local model. Specifically, for each command the proper local real time model is constructed and quickly analyzed to determine the effects on the power system. The analytics determine the effect of the command, if executed, on the system and in particular on the operational reliability of the system. In case of a command that may have adverse effects on the operational reliability of the system, the command will be blocked and the operator will be alerted. In addition to the command authentication at the relay level, an open-source real-time network monitoring system for capturing and parsing network traffic is presented. Because the method is based on the substation level dynamic state estimator which uses only local substation level measurements and data, a byzantine type attack is not considered possible for the proposed approach. Finally, a discussion on the architecture required to integrate the network monitoring and state estimation sys- ems is presented. The methodology is presently being tested in a laboratory setup that includes a digital simulator of the electric power system and hardware in the loop.