Sharif Digital Repository

Modern power systems have been faced with a rising appeal for the upgrade to a highly intelligent generation of electricity networks known as the smart grid. Thus, security for the smart grid has emerged as an important issue. Recently, Hur proposed an attribute based data sharing for smart grid which unfortunately is vulnerable to the denial of service (DoS) attack. Moreover, it does not support the user revocation property and the grid system manager cannot prevent the revoked user of having access to the shared data in the storage center. For these weaknesses, we suggest an efficient revocable data sharing scheme which is immune against DoS attack. In addition, we present the security... 

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo dodecane (CL-20)-based polymer/plastic bonded explosives are used in propellant formulation. It can be predicted that CL-20-based nano-polymer/plastic bonded explosives are able to have reduced composite sensitivity and superior mechanical strength. In the current study, we have prepared two kinds of CL-20-based nano-polymer/plastic bonded explosives with ethylene-vinyl acetate copolymer and glycidyl azide polymer via the microemulsion method. Several visual techniques such as SEM/AFM/TEM techniques have been utilized for complete characterization of CL-20-based... 

Nicanfar and Leung proposed a multilayer consensus elliptic curve based password authenticated key-exchange (MCEPAK) protocol for smart grid. They claimed that their protocol is secure against possible attacks. In this paper, we show that the MCEPAK protocol is vulnerable to the dictionary attack and an adversary can obtain the passwords of the appliances by eavesdropping the communicated messages in the protocol. Moreover, we state that the passwords can be discovered by curious operators of the building area networks and the neighbor area networks. Theses weaknesses motivated us to introduce a chaotic maps based authenticated key exchange protocol for smart grid. To the best of our... 

Vehicular Ad-hoc Networks (VANETs) will start becoming deployed within the next decade. Among other benefits, it is expected that VANETs will support applications and services targeting the increase of safety on the road, and assist in improving the efficiency of the road transportation network. However, several serious challenges remain to be solved before efficient and secure VANET technology becomes available, one of them been efficient authentication of messages in a VANET. In this paper, we analyse a recent authentication scheme for VANETs introduced by Lee et al. Unfortunately this scheme is vulnerable to the impersonation attack so that a malicious user can generate a valid signature... 

The current multi-channel P2P video streaming architectures still suffer from several performance problems such as low Quality of Service (QoS) in unpopular channels. The P2P systems are inherently dynamic, and their performance problems could be categorized into four groups; peer churn, channel churn, uncooperative peers, and geographical distribution of peers. In this paper, for the first time, we develop a novel locality-incentive framework for multi-channel live video streaming. We propose a hierarchical overlay network architecture by utilizing a dual-mode locality-Awareness method (spatial and temporal). Moreover, an incentive mechanism for encouraging peers to dedicate their upload... 

Node localization is of paramount importance to different wireless sensor network (WSN) applications. This paper investigates the received signal strength (RSS) based localization problem with unknown path-loss model parameters. Most works in RSS localization assume the transmit power and path-loss exponent (PLE) are known that is not a realistic assumption in some cases. However this paper, assumes the transmit power and the PLE are both unknown and a novel algorithm for sensor location is proposed. The algorithm is based on the generalized total least-squares (GTLS) method and gives an explicit solution for the localization problem. The performance of the proposed method is compared with... 

Strong designated verifier signature scheme is a concept in which a user (signer) can issue a digital signature for a special receiver; i.e. signature is produced in such way that only intended verifier can check the validity of produced signature. Of course, this type of signature scheme should be such that no third party is able to validate the signature. In other words, the related designated verifier cannot assign the issued signature to another third party. This article proposes a new ID-based strong designated verifier signature scheme which has provable security in the ROM (Random Oracle Model) and BDH assumption. The proposed scheme satisfies the all security requirements of an... 

The problem of time delay estimation (TDE) in the presence of zero mean white Gaussian noise is addressed. A novel and efficient algorithm for obtaining Conditional Maximum Likelihood (CML) estimates of delays, attenuation factors and the number of paths from a transmitter to a receiver is introduced. This approach is quite suitable for the cases in which time delay difference is less than the duration of signal autocorrelation  

This paper presents a method for the optimal allocation of Distributed generation in distribution systems. In this paper, our aim would be optimal distributed generation allocation for voltage profile improvement and loss reduction in distribution network. Genetic Algorithm (GA) was used as the solving tool, which referring two determined aim; the problem is defined and objective function is introduced. Considering to fitness values sensitivity in genetic algorithm process, there is needed to apply load flow for decision-making. Load flow algorithm is combined appropriately with GA, till access to acceptable results of this operation. We used MATPOWER package for load flow algorithm and... 

Multiple target detection in conventional PCL (Passive Coherent Location) radar systems by means of Ambiguity Function Processing and without any powerful algorithm is impossible. Presented Gradual Clean Algorithm (GCA) is a new and simple method, which could provide the perfect detection in noisy environment and heavy clutter condition up to SNR=-15 dB and SCR=-100 dB (clutter is assumed as a distributed target with large RCS). Determining the number of real targets and keeping the false alarm probability approximately constant are the presented algorithm capabilities  

There are inherent errors in target location and velocity measurement caused by bistatic geometry in addition to the errors that are caused in monostotic radars. In this paper, the accuracy of measurement with respect to some parameters like baseline variance and DOA estimation is considered and bistatic parameters sensitivity with respect together is formulated  

To make a balance between time of detection and resolution of detection in radar, it must select an optimized time interval for integrations and signal bandwidth. In this paper, a new algorithm for finding best width of window and bandwidth of the FM signals for FM PCL radar is designed  

This paper presents efficient estimators to address the problem of source localization aided by unmanned aerial vehicles (UAVs) with unknown location parameters. Leveraging semidefinite relaxation technique and successive weighted least squares estimation, the source and UAV parameters are simultaneously estimated in both mixed line-of-sight/non-line-of-sight (NLOS) and NLOS scenarios. The proposed estimators are shown to approximately achieve the Cramer-Rao bound (CRB) under mild Gaussian noise conditions when the measurement noises are small compared to the associated ranges. Numerical simulations demonstrate that localization without prior UAV location information is still possible with a... 

Recently, using Peer-to-Peer (P2P) overlay architectures have become a popular approach for live video streaming over the Internet. Since the peers in these systems are geographically distributed, the communication between them imposes huge redundant traffic into the Internet. One solution to address this problem is utilizing the locality aware algorithms to optimize the neighbor selection policy. However, for real-time applications like live video streaming we need to consider the trade-off between localizing the traffic and service quality. In this paper, we propose a novel pure P2P framework through two phases; (1) Local tracker selection, and (2) Overlay mesh construction. We introduce... 

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) as one of the high energy cage nitramines has been used in various propellants and explosive formulations. The performance of energetic materials depends on its particle size and shape. Therefore, in this research, microemulsion method has been applied for the preparation of CL-20 nanoparticles via oil in water (O/W) microemulsions. The optimized formulation contains water 45%, n-butyl acetate 20.5%, sodium dodecyl sulfate (SDS, as anionic surfactant) 6.5% and 2-propanol (as co-surfactant) 26.5%. CL-20 nanoparticles that were obtained by microemulsion method are spherical with an average diameter of 25 nm, based on TEM image.... 

A theory is presented for the quantum radiation emitted from a single exciton in a quantum dot. We assume that the quantum dot is in strong coupling to a slab photonic crystal cavity. A dielectric function of spatial coordinates is used to explain the effects of the macroscopic medium. It has been proved that the electric field in such a medium can be described using the so-called K-function. We derive a formula for obtaining the frequency spectrum, and present an analytical result for the optical spectrum, which is dependent on the K-function. We also have considered a slab photonic crystal configuration with hexagonal structure containing a cavity to evaluate the frequency spectrum in such... 

In the past decades, Vehicular Ad hoc Networks (VANETs) have been increasingly developed. Providing secure and efficient communication is essential in VANETs. One of most important challenges in the secure and efficient communications is proposing an appropriate authentication scheme. In this paper, we suggest an efficient and novel authentication scheme for VANETs. In the proposed scheme, vehicles authenticate each other without any limitation such as need for group of signers, online Road Side Units (RSUs), a set of pseudo identities and tamper-proof devices. Moreover, our simulation shows that the proposed scheme is well designed and efficient. © 2019, © 2019 Taylor & Francis Group, LLC  

In recent decades, utilizing of water-based muds (WBMs) in drilling oil and gas wells is ever increasing comparing to oil-based muds and synthetic-based muds due to the lower environmental issues. However, the main drawbacks with WBMs are rheological properties inefficiency and shale swelling which have caused attentions turn to improvement of WBMs’ rheological properties. In this study, the effects of various nanoparticles (NPs) namely titanium dioxide (TiO2), silicon dioxide (SiO2), and zinc oxide (ZnO) on improving rheological properties and shale recovery rate of a WBM sample at two temperatures (25 and 50 °C) were investigated. The concentrations of NPs in the base mud were set at 0.01,... 

Cryptographic algorithms utilize finite-field arithmetic operations in their computations. Due to the constraints of the nodes which benefit from the security and privacy advantages of these algorithms in sensitive applications, these algorithms need to be lightweight. One of the well-known bases used in sensitive computations is dual basis (DB). In this brief, we present low-complexity superserial architectures for the DB multiplication over GF (2m). To the best of our knowledge, this is the first time that such a multiplier is proposed in the open literature. We have performed complexity analysis for the proposed lightweight architectures, and the results show that the hardware complexity... 

This study investigated the removal of triethylamine using a biotrickling filter. The influence of affecting parameters, such as height and recirculation liquid rate (VL) on contaminant removal efficiency, was examined in detail. The results demonstrated that in the constant empty bed residence time (EBRT), when VL was increased, the removal efficiency (RE) increased. Also, for a specific VL, increasing EBRT could also increase RE values. However, it seems that an increasing VL is a more cost-effective way to enhance RE as compared to an increasing EBRT. The obtained outcomes represented that for a constant EBRT, an increase in inlet loading (IL) could decrease RE. For lower ILs, the removal...