Sharif Digital Repository

It is known that discrete scale invariance leads to log-periodic corrections to scaling. We investigate the correlations of a system with discrete scale symmetry, discuss in detail possible extension of this symmetry such as translation and inversion, and find general forms for correlation functions. © 2003 Published by Elsevier Science B.V  

This study presents and analyses a novel joint detection and parameters estimation of multiple targets using a co-located multiple input/multiple output radar with moving platform, in the presence of clutter and background noise. A notable feature of the proposed approach is that clutter cancellation is independent of received data. Moreover, to decrease the computational load, the authors propose to perform the target detection and parameters estimation by directly processing on the compressive measurements as opposed to Nyquist samples. © The Institution of Engineering and Technology  

Gastpar and Vetterli named the adhoc networks with one randomly selected source-destination pair as relay networks and they suggested using arbitrary network coding in order to increase the overall efficiency Here, the relay network is investigated with two relays and no interference and a new achievable rate is obtained using a new network coding (decodeand-broadcast). The obtained achievable rate (i) gives the lower bound for the general relay channel, obtained by Cover and El Gamal, but with slight difference due to no interference assumption at the receiver (ii) includes the one relay rates of a two-level relay channel studied by Gupta and Kumar using point to point coding, (iii)... 

This article is focused on developing an Energy Service Company (ESCO) risk assessment model for use by energy savings certificates (ESC) market regulators. This model enables market regulators to determine the appropriate point in time for ESCOs to sell their certificates with the aim of minimizing risk as well as maximizing economic gain yet remain motivated for reducing the cost of energy efficiency technologies. To this end, the interactions between an ESCO and other parties (such as suppliers) in the market in addition to the principles of the energy efficiency performance contract are taken into consideration. Then, appropriate probability distributions have been fitted to the... 

Carbon-based sensors are attractive because of their excellent sensing capability. In this paper, we propose a new approach to analytically model the sensitivity of these devices based on graphene. The model relies on the surface potential and current of the device. For the first time, we included ionization in the modelling and examined the importance of this effect. In order to validate the model, the results are compared with experimental data from a fabricated device  

Capacity has been found for degraded, reversely degraded, full feedback, semi-deterministic, orthogonal relay channels, also for a class of deterministic relay channels and a class of modulo sum relay channels. We indicate what the relay decodes and forwards with one auxiliary random variable having bounded cardinality and attempt to define a more general class of relay channels in order to unify most of known capacity theorems into one capacity theorem by considering additional assumptions imposed to the definition of those channels. In other words, the relay channel inputs are dependent as in multiple access channel with arbitrarily correlated sources and here we do for the relay channel... 

In this paper, we study theoretically the generation of high repetition rate short pulses using fiber optical parametric amplification. We show that the pulse shape and duration depend on the signal location relatively to the pump frequency. We demonstrate that in order to get the shortest pulse width, the signal must be located at one of the extremities of the gain spectrum associated with the pump peak power. We derive the analytical expression of the pulse shape in this case and compare it to the exponential gain regime case. Using numerical simulations, we also analyze the impact of walk-off and pump phase modulation that is required to suppress Stimulated Brillouin Scattering and derive... 

This paper reports a polarization controllable and angle-insensitive perfect metamaterial absorber (PMA). The proposed PMA consists of periodically arranged asymmetric omega-shaped resonators made of metallic copper. The absorptivity was analyzed considering the microwave C-band from 4 GHz to 8 GHz. The proposed PMA shows an absorption peak with almost 100% absorptivity at 6.2 GHz. Also, wideband negative index of refraction is observed. Further, the absorber is inspected for the different rotation angles of the top metasurface (omega-shaped ring) along the optical axis, and obliquity of incidence angle for both TE and TM polarized waves. Moreover, surface electric field and surface current... 

In cloud computing, services play key roles. Services are well defined and autonomous components. Nowadays, the demand of using Fuzzy inference as a service is increasing in the domain of complex and critical systems. In such systems, along with the development of the software, the cost of detecting and fixing software defects increases. Therefore, using formal methods, which provide clear, concise, and mathematical interpretation of the system, is crucial for the design of these Fuzzy systems. To obtain this goal, we introduce the Fuzzy Inference Cloud Service (FICS) and propose a novel discipline for formal modeling of the FICS. The FICS provides the service of Fuzzy inference to the... 

The mixed nano-ferrites materials Cu0.6Zn0.4HoxFe2−xO4 (0.00 ≤ x ≤ 0.12) were prepared via the sol–gel auto combustion technique. The TGA curve established the annealing temperature (500 °C) for phase formation. The single exothermic peak on the DSC plot occurred at 341 °C temperature. XRD patterns of these nano ferrites verified single phase formation of the FCC cubic structure. The lattice constant a was increased from 8.4244 to 8.4419 Å and then its value decreased to 8.4319 Å. Crystallite size was found in the range of 7 to 16 nm. The surface morphology of the samples was observed from the scanning electron microscope (SEM) images. The grain size was found within the range of 90 nm to... 

The mixed nano-ferrites materials Cu0.6Zn0.4HoxFe2−xO4 (0.00 ≤ x ≤ 0.12) were prepared via the sol–gel auto combustion technique. The TGA curve established the annealing temperature (500 °C) for phase formation. The single exothermic peak on the DSC plot occurred at 341 °C temperature. XRD patterns of these nano ferrites verified single phase formation of the FCC cubic structure. The lattice constant a was increased from 8.4244 to 8.4419 Å and then its value decreased to 8.4319 Å. Crystallite size was found in the range of 7 to 16 nm. The surface morphology of the samples was observed from the scanning electron microscope (SEM) images. The grain size was found within the range of 90 nm to... 

Machine-to-Machine (M2M) communication is an important type of communication in the Internet-of-Things (IoT). How to send data in these high-density communications using relay selection can help improve the performance of this type of communication in various applications. In addition, the possibility of simultaneous use of different Radio Frequency (RF) interfaces helps to use the spectrum more efficiently. In this work, we try to further use machine communication RF equipment and improve the average data rate of networks in some applications such as the IoT, which have their own bandwidth requirements. Therefore, we provide an optimization algorithm for relay selection as well as the... 

In the study presented herein, a simple method for laboratory calcite cementation of a reconstituted gravelly sand was presented. This method was used to prepare cemented gravelly sand specimens, which have similar natural characteristics to alluvial deposit of the city of Tehran. The formation and distribution of calcite bonds, as well as the effectiveness of the presented calcite cementation method in increasing interparticle cohesion, as observed in weakly to moderately cemented soil in Tehran, were evaluated by means of chemical analysis, X-ray diffraction technique, and unconfined compressive strength tests. The cementation technique was used to prepare triaxial specimens with calcite... 

The development of new technologies has confronted the entire domain of science and industry with issues of big data's scalability as well as its integration with the purpose of forecasting analytics in its life cycle. In predictive analytics, the forecast of near-future and recent past - or in other words, the now-casting - is the continuous study of real-time events and constantly updated where it considers eventuality. So, it is necessary to consider the highly data-driven technologies and to use new methods of analysis, like machine learning and visualization tools, with the ability of interaction and connection to different data resources with varieties of data regarding the type of big... 

Norouzak oil seeds that are the source of bio-diesel (Norouzak) fuel grow mostly in Gonabad and Kashmar located in Khorasan, north east of Iran. Spray characteristics of Norouzak bio-diesel have been experimentally and theoretically studied in this work. Norouzak fuel is added to the conventional diesel fuel, and mixture formations of several blends have been investigated and compared with each other. Moreover, by varying ambient and injection conditions, behaviors of spray of different blends have been explored. Microscopic and macroscopic properties of spray such as Sauter Mean Diameter (SMD), Ohnesorge number, spray tip penetration, spray cone angle, spray projected area and volume have... 

Norouzak oil seeds that are the source of bio-diesel (Norouzak) fuel grow mostly in Gonabad and Kashmar located in Khorasan, north east of Iran. Spray characteristics of Norouzak bio-diesel have been experimentally and theoretically studied in this work. Norouzak fuel is added to the conventional diesel fuel, and mixture formations of several blends have been investigated and compared with each other. Moreover, by varying ambient and injection conditions, behaviors of spray of different blends have been explored. Microscopic and macroscopic properties of spray such as Sauter Mean Diameter (SMD), Ohnesorge number, spray tip penetration, spray cone angle, spray projected area and volume have...