Sharif Digital Repository

One of the main challenges in arid and semi-arid regions is the lack of water for various purposes such as industrial and agricultural applications. The problem is even more significant in traditional agriculture. The geographical location, climatic conditions, average annual rainfall, vegetation, air pollution and turbidity, and canopy of plants are important and lead to different water consumption in plants. Therefore, proper water consumption in agriculture in most countries leads to food security and a better supply of crops. In this research, we propose a fuzzy system that has eight inputs and seven outputs. Inputs include soil moisture, relative humidity, air temperature, wind speed,... 

Many research works have been done in face recognition during the last years that indicates the importance of face recognition systems in many applications including identity authentication. In this paper we propose an approach for face recognition which is suitable for unconstrained image acquisition and has a low computational cost. Since in practical applications such as in smartphones, imaging conditions are not limited to existing images in the database, robustness of the recognition algorithm is very important. Here a sparse representation framework is proposed which achieves some degree of robustness. Using double sparse representation the high computational cost of sparsity-based... 

Radiation-induced multiple event transients (METs) are expected to become more frequent than single event transients (SETs) at nanoscale CMOS technology nodes. In this paper, a fast and accurate layout-based soft error rate (SER) assessment technique with consideration of both SET and MET fault models is presented. Despite existing techniques in which the adjacent MET sites are extracted from a logic-level netlist, we conduct a comprehensive layout analysis to obtain MET adjacent cells. Experimental results reveal that the layout-based technique is the only viable solution for identification of the adjacent cells as netlist-based techniques considerably underestimate the overall SER.... 

Similarity solutions are carried out for flow of power law non-Newtonian fluid film on unsteady stretching surface subjected to constant heat flux. Free convection heat transfer induces thermal boundary layer within a semi-infinite layer of Boussinesq fluid. The nonlinear coupled partial differential equations (PDE) governing the flow and the boundary conditions are converted to a system of ordinary differential equations (ODE) using two-parameter groups. This technique reduces the number of independent variables by two, and finally the obtained ordinary differential equations are solved numerically for the temperature and velocity using the shooting method. The thermal and velocity boundary... 

Following the fact that there are some efficient implementations of ECC-based RFID authentication protocols on RFID tags, a new family of RFID authentication protocols known as EC-RAC family has been introduced. However, it has been shown that all the versions of EC-RAC protocols are exposed to privacy and/or security threats. In this paper we analyzed a version of the EC-RAC RFID authentication protocol as well as a version of Schnorr protocol which were presented in a recent work and are claimed to have the demanding requirements. We demonstrated an impersonation attack on the claimed improved EC-RAC, and consequently showed that it would not satisfy the tag authentication property. Also,... 

Recently, AIDA/cube testers have been revealed to be useful in building distinguishers for several cryptography schemes. χ2 tests, on the other hand, are well known and extensively used for distinguishing purposes. In this study, the notion of multi-χ2 test and AIDA/cube testers are utilised to introduce the superpoly algebraic normal form monomial test through which the output of reduced round Trivium is distinguished from being random. The test successfully distinguishes the keystream of Trivium with 830 out of 1152 initialisation rounds with a complexity of 239 operations, which is the most effective distinguisher on reduced Trivium thus far. Applying algebraic IV differential attack... 

Eslami and Talebi (2011) [25] proposed an untraceable electronic cash scheme and claimed that their scheme protects the anonymity of customers, detects the identity of double spenders and provides the date attachability of coins to manage the bank database. In this paper, illustrating Eslami and Talebi's scheme, as one of the latest untraceable electronic cash schemes, and showing its weaknesses (in fulfilling the properties of perceptibility of double spender, unforgeability and date attainability of coins) and its faults (related to exchange protocol), we propose a new untraceable electronic cash scheme which is immune to the weaknesses of the former. Our scheme contains anonymity,... 

In this paper we show that Biham's chosen key attack can be generalized to include any block cipher and we give a low complexity chosen key attack on any Feistel type ci-pher. Then we show that the irregularities in the shift pattern of DES key schedule algorithm is not sufficient for the cryptosystem to resist against related key attacks. We have realized our proposition by a counter example in which the E-box of DES is slightly modified whiles other components and among those, the shift pattern in key schedule algorithm is kept unchanged. We have ap-plied a new related key attack on the resulting DES-like cryptosystem and demonstrated that the security of the system decreases drastically  

Chi-square tests are vastly used for distinguishing random distributions, but extra care must be taken when using them on several independent variables. We noticed, the chisquare statistics, in some previous works, was computed half of its real value. Thus, to avoid possible future confusions, we formulize multiple-chi-square tests. To show the application of multiple-chi-square tests, we introduce two new tests and apply them to Trivium as a special case. These tests are modifications of ANF monomial test and, when applied to Trivium with the same number of rounds, the data complexity of them is roughly 24 times smaller than that of previous ANF monomial test  

Metal matrix composite coatings have gained great attention due to their exclusive properties. They have shown the properties of a metallic host material modified by addition of a second phase. In electrodeposition of Ni/WC nano composite, nickel was deposited on the substrates by DC electrodeposition in Watt's based bath containing nickel sulfate, nickel chloride, boric acid and sodium dodecyl sulfate. WC content in the coating was determined by different parameters such as current density, powder content and surfactant amount. Mechanism of electrodeposition was analyzed by cyclic voltammetry and was confirmed by Guglielmi model. Surface morphology was studied by scanning electron...