Sharif Digital Repository

It has been known for many years that the type of soil under structures affects the structural performance during earthquakes. In fact, the soil affects the structural response in two ways, through the change in the free-field motion (usually known as the site effect) and due to Soil- Structure Interaction (SSI). The site effect has been included in the seismic codes from the most beginning. However, the SSI effect had not attracted much attention. The most significant intervention in this regard has been the 1978 inclusion of SSI in the tentative provisions of ATC3-06 in the United States, which is based on the results of studies on elastic response of soil structure systems. The effect of... 

An efficient method is reported for selective oxidation of various types of sulfides to sulfoxides and sulfones in good to high yields using 30% H 2O2 in the presence of catalytic amounts of molybdate-based catalyst in acetonitrile as solvent at room temperature. The catalyst can be easily recovered and reused for seven reaction cycles without considerable loss of activity  

In vehicular ad-hoc networks (VANETs), the correctness of a message requires authentication of the origin vehicle.In this paper, we introduce a novel authentication scheme for VANETs which suggests a new solution for secure vehicle communications. The proposed scheme is an road side unit (RSU) based scheme in which the master key of the Trusted Authority (TA) is embedded in a tamper-proof device provided at the RSUs. Compared with the schemes that store the master key in the on-board units, our scheme is more practical because of a secure and high speed communication link between TA and RSUs. To the best of our knowledge,this solution has not yet been devised for secure authentication in... 

Cryptographic computation exploits finite field arithmetic and, in particular, multiplication. Lightweight and fast implementations of such arithmetic are necessary for many sensitive applications. This brief proposed a low-complexity systolic Montgomery multiplication over GF(2m). Our complexity analysis shows that the area complexity of the proposed architecture is reduced compared with the previous work. This has also been confirmed through our application-specific integrated circuit area and time equivalent estimations and implementations. Hence, the proposed architecture appears to be very well suited for high-throughput low-complexity cryptographic applications  

Karun Bridge is part of a national highway project underway in southern Iran. The bridge is a 336 m steel arch structure that weighs more than 2500 tons and crosses the Karun River 270 meters above the river valley. The bridge will be the largest suspended bridge in the Middle East. Cantilever construction is to be used to construct the bridge from both sides simultaneously. The weight of the bridge is to be carried by two abutments and four piers that are anchored to exposed weathered rock mass. Loads on the abutments and piers include significant cantilever loads and moments during bridge erection and wind loads. Daily rapid temperature changes also will impart significant thermal loads on... 

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... 

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... 

Authentication schemes play vital roles in computer and communication security. In order to authenticate the remote users, password based schemes have been widely used. In this paper we introduce a secure remote user authentication scheme based on bilinear pairing that satisfies all security requirements which are mentioned for password based authentication schemes using smart card  

This paper deals with the problem of designing the PI λDμ-type controllers for minimum-phase fractional systems of rational order. In such systems, the powers of the Laplace variable, s, are limited to rational numbers. Unlike many existing methods that use numerical optimisation algorithms, the proposed method is based on an analytic approach and avoids complicated numerical calculations. The method presented in this paper is based on the asymptotic behaviour of fractional algebraic equations and applies a delicate property of the root loci of the systems under consideration. In many cases, the resulted controller is conveniently in the form of P, Iλ, PDμ or PIλDμ. Four design examples are... 

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... 

This paper presents a numerical algorithm for BIBO stability testing of a certain class of the so-called fractional-delay systems. The characteristic function of the systems under consideration is a multi-valued function of the Laplace variable s which is defined on a Riemann surface with finite number of Riemann sheets where the origin is a branch point. The stability analysis of such systems is not straightforward because there is no universally applicable analytical method to find the roots of the characteristic equation on the right half-plane of the first Riemann sheet. The proposed method is based on the Rouche's theorem which provides the number of the zeros of a given function in a... 

This paper deals with the boundary control problem for a certain class of linear infinite-dimensional systems commonly known as fractional-delay systems. It is assumed that the systems under consideration are, in general, described by multi-valued transfer functions. In this paper, we restrict our studies to a class of multi-valued transfer functions which are defined on a Riemann surface with limited number of Riemann sheets where the origin is a branch point. The proposed controller design algorithm is based on shaping the sensitivity function. Contrary to many other methods which approximate the underlying infinite-dimensional system by a finite-dimensional one and then apply a classical... 

The exact stability condition for certain class of fractional-order (multivalued) transfer functions is presented. Unlike the conventional case that the stability is directly studied by investigating the poles of the transfer function, in the systems under consideration, the branch points must also come into account as another kind of singularities. It is shown that a multivalued transfer function can behave unstably because of the numerator term while it has no unstable poles. So, in this case, not only the characteristic equation but the numerator term is of significant importance. In this manner, a family of unstable fractional-order transfer functions is introduced which exhibit... 

The correlation between extreme precipitation and flood magnitude is still poorly understood because of the complex mechanisms controlling flood generation. In this study, we used 50 years of precipitation and streamflow data across Iran to analyse the spatial distribution, slope, and significance of long-term trends in extreme precipitation compared to the spatial distribution of long-term trends for flood magnitude and frequency. Despite the decreasing trend of extreme precipitation in 60% of Iran’s sub-basins, the flood magnitude showed an increasing trend. In particular, the number of flooding days with a return period of 25~50 years and >50 years in 2010s has increased by 1.3 and 2.2... 

Memristor is the fourth fundamental passive circuit element which has potential applications in development of analog memristive memories, neuroscience, and brain simulation. In all of these applications the memristance of the device should be adjusted to the desired value, which is currently performed by trial and error. The aim of this paper is to propose a new method and develop a circuit for automatic adjustment of the memristance of memristive devices. The proposed method is based on the sliding mode control and numerical simulations show that it can be used for tuning the memristance of such devices with a high accuracy  

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 voltammetric performance of edge-plane pyrolytic graphite (EPG) electrode via adsorptive stripping voltammetry was investigated for study of the electrochemical behavior of omeprazole (OMZ) in aqueous solution. The results revealed that the oxidation of OMZ is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism. The determination conditions, such as the pH values of the supporting electrolyte, accumulation time and scan rate were optimized. Simplicity, high reproducibility and low detection limit (3 nM) of the electrode response as well as wide linear range (0.01 to 4.0 µM) can be stated as significant... 

Secure computation has obtained significant attention in the literature recently. Classic architectures usually use either the Garbled Circuit (GC) or the Goldreich-Micali-Wigderson (GMW) protocols. So far, to reduce the complexity of communications in these protocols, various methods have been proposed. The best known work in both methods reduces the communication up to almost 2k-bits (k is the symmetric security parameter) for each AND gate, and using XOR gate is free. In this paper, by combining GC and GMW, we propose a scheme in the semi-honest adversary model. This scheme requires an Oblivious Transfer (OT) and a 2-bit data transfer for each AND gate, keeping XOR gates free. The... 

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  

In this paper, first we present a new explanation for the relationship between logical circuits and artificial neural networks, logical circuits and fuzzy logic, and artificial neural networks and fuzzy inference systems. This shows us that neural networks are working in the same way as logical circuits when the connection between them is through the fuzzy logic. However, themain difference between them is that logical circuits can be constructed without using any kind of optimization-based learning methods. Based on these results, we propose a new neuro-fuzzy computing system. As verified by simulation results, it can effectively be implemented on the memristor crossbar structure and...