Sharif Digital Repository

In the present research work, an environmental policy procedure for setting a cap on emissions, as a crucial step in any total emission control system, has been provided and evaluated. It is shown that general regulations on emission intensities and rates do not guarantee that ambient air quality standards are met in intense industrial zones. Local emission limits are necessary to meet ambient air quality standards in these zones. To that end, we used dispersion simulators to back-calculate pollutant concentration thresholds for a large and intense energy system in the Assaluyeh region of southern Iran. Verified modeling results indicate 218 d of pollutant concentration threshold exceedance... 

A specific class of differential cryptanalytic approach, named as impossible differential attack, has been successfully applied to several symmetric cryptographic primitives in particular encryption schemes such as Advanced Encryption Standard (AES). Such attacks exploit differences that are impossible at some intermediate state of the cipher algorithm. The best-known impossible differential attack against AES-128 has applied to six rounds. An attack on AES-128 up to seven rounds is proposed. The proposed attack requires 2115.5 chosen plaintexts and 2109 bytes of memory and performs 2119 seven-round AES encryptions. This is also the best-known attack on a reduced version of the AES-128 till... 

A novel error resilient source coding method is proposed for video codecs such as H.264 standard. The main idea is to develop an error resilient part similar to the channel coders at the source coder. This enables the receiver to recover a damaged slice of a frame, inter or intra coded, up to a certain size determined by the encoder. In contrast to another previously approach presented in the literature, our algorithm has significantly less artifacts on the video frames with a considerable increase in speed  

In this paper we describe two differential fault attack techniques against Advanced Encryption Standard (AES). We propose two models for fault occurrence; we could find all 128 bits of key using one of them and only 6 faulty ciphertexts. We need approximately 1500 faulty ciphertexts to discover the key with the other fault model. Union of these models covers all faults that can occur in the 9th round of encryption algorithm of AES-128 cryptosystem, One of main advantage of proposed fault models is that any fault in the AES encryption from start (AddRoundKey with the main key before the first round) to MixColumns function of 9th round can be modeled with one of our fault models. These models... 

In a comparative analysis performance and capacity of DECT, PACS, and PHS for wireless local loop applications have been investigated. This article reports the results of both qualitative and quantitative analyses. The qualitative evaluation consists of a detailed comparison of the parameters of each standard and their relevance in WLL applications. In the quantitative analysis detailed simulations were performed covering diverse sets of conditions. The results of both types of analysis are presented. A major conclusion is that all three standards provide satisfactory performance for WLL applications. For low traffic environments PACS, which can employ larger cells, performs better than the... 

In a comparative analysis performance and capacity of DECT, PACS, and PHS for WLL applications have been investigated. This article reports the results of both qualitative and quantitative analysis. The qualitative evaluation consists of a detailed comparison of the parameters of each standard and their relevance in WLL applications. In the quantitative analysis detailed simulations have been performed covering diversified sets of conditions. The results of both types of analysis are presented. A major conclusion is that all three standards provide satisfactory performance for WLL applications. For low-traffic environments PACS, which can employ larger cells, performs better than the other... 

The extensive quantum-chemical calculations are assessed for prediction of the 19F nuclear magnetic shielding constants. The methods within domain of density functional theory (DFT) and ab initio, Hartree-Fock (HF), and second-order Møller-Plesset perturbation theory (MP2) are employed for calculation of the 19F chemical shielding constants for a series of 30 small fluorine-containing molecules. The importance of inclusion of four factors, namely, electron correlation treatment, triple-ξ valence shell, diffuse function, and polarization function on calculating the fluorine NMR chemical shieldings for a variety of Pople's standard basis sets at gauge invariant atomic orbital (GIAO) and... 

An extensive GIAO (gauge-including atomic orbital) calculation has been made within Hartree-Fock (HF), density functional theory (DFT) and second-order Møller-Plesset perturbation theory (MP2), in conjunction with selected basis sets for the prediction of 19F chemical shift values of 26 different F nuclei in small fluorine-containing molecules. The effect of four factors, namely, electron correlation treatment, triple-ξ valence shell, diffuse function and polarization function were assessed using a systematic comparison of the results. Based on types of series, the optimized wave functions were proposed for different molecules. An additional comparison of the principal components of the... 

The observation of a new b baryon via its strong decay into Ξb-π + (plus charge conjugates) is reported. The measurement uses a data sample of pp collisions at √s=7TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 5.3fb -1. The known Ξb- baryon is reconstructed via the decay chain Ξb-→J/ψΞ -→μ +μ -Λ0π -, with Λ0→pπ -. A peak is observed in the distribution of the difference between the mass of the Ξb-π + system and the sum of the masses of the Ξb- and π +, with a significance exceeding 5 standard deviations. The mass difference of the peak is 14.84±0.74(stat)±0.28(syst)MeV. The new state most likely corresponds to the JP=3/2 + companion of the Ξ b  

Hartree-Fock and density functional theory methods at gauge invariant atomic orbital approach with different simplest basis sets were employed for the computation of chemical shifts. The wave functions for calculating gas-phase 1H and 13C chemical shifts have been optimally selected using empirical models. The effects of electron correlation treatment, triple-ξ valance shell, diffuse function, and polarization function on calculated chemical shifts have been discussed. Through empirical scaling of shielding, accurate predictions of 1H chemical shifts are achieved for the molecules studied, when considering small Pople basis sets. Gas phase experimental 1H chemical shifts in alcohols, amines... 

This research has modelled a queuing system with no standard states. In order to analyse these systems, some parameters such as the mean of waiting time and the length of queue are computed. These situations usually occur when there is delay in the service, for example, in the gas queuing system that cars are unable to leave after receiving the required services due to the presence of other cars in front of them. These kinds of non-standard queuing systems are usually applied to the assembly and production lines. In this paper, a queuing model for the special non-standard state queuing system is developed to be used in gas stations. The proposed model is implemented in fuel stations in Iran... 

In this work, we study the large scale structure formation in the modified gravity in the framework of Palatini formalism and compare the results with the equivalent smooth dark energy models as a tool to distinguish between these models. Through the inverse method, we reconstruct the dynamics of universe, modified gravity action and the structure formation indicators like the screened mass function and gravitational slip parameter. Consequently, we extract the matter density power spectrum for these two models in the linear regime and show that the modified gravity and dark energy models predictions are slightly different from each other at large scales. It is also shown that the growth... 

Frame aggregation (FA) mechanisms improve the throughput of WLANs. In this paper, the effect of the FA mechanism on the throughput of wireless local area networks (WLANs) has been investigated. To this end, we propose an analytical model in order to analyze an IEEE 802.11n network comprised of an access point (AP) and several conventional nodes (CNs), all in the coverage area of each other. With respect to the heavier download traffic compared to the upload one, in our scenario, only the AP uses an FA mechanism and the other nodes use the basic IEEE 802.11 standard. In our proposed analytical model, the maximum downlink (DL) throughput is derived. Regarding the asymmetry among nodes, our... 

In this paper, we propose a new trust-region method for solving nonlinear systems of equalities and inequalities. The algorithm combines both standard and adaptive trust-region frameworks to construct the steps of the algorithm. The trust-region subproblem is solved in the first iteration using a given initial radius. Then, in each iteration, the standard trust-region method is followed whenever the current trial step is accepted, otherwise, the subproblem is resolved using an adaptive scheme. The convergence results for the new proposed algorithm are established under some mild and standard assumptions. Numerical results on some least-squares test problems show the efficiency and... 

Standard-form contracts facilitate the sophisticated public-private partnership (PPP) procurement process. Special care should be taken during the preparation of these documents since any remaining flaws affect subsequent projects. Reviewing the standard-form contract capabilities after its application help to identify its major flaws and improve the contract clauses. This research proposed a novel structured method to address this need and verified its capability. In the proposed method, a comprehensive list of risks is first created for the PPP projects in the specified project environment. The identified risks are prioritised to highlight the priority of the required adjustments in the... 

One of the methods introduced for establishing hidden communication is steganography. Steganography is the art of hiding information in a cover media without attracting attention. Text documents are one of the common cover media used for steganography in past. Steganography in text is more difficult than other media because there is a little redundant information in text documents. In this study, we propose a high capacity text steganography method. Our method can hide about 400 bits in each kilobyte of text. In Persian and Arabic, each letter can have four different shapes regarding to its position in the word. In this method this feature of Persian and Arabic languages is used for... 

Sending information secretly and communicating covertly have been of great interest for ages. On the other hand, text documents have been widely used and consequently various methods for hiding information in texts (Text Steganography) have been developed so far. In this paper a new method is proposed to hide information in digital Persian and Arabic Unicode texts. In Persian and Arabic, each letter can have four different shapes regarding to its position in the word. In this method by using this feature of Persian and Arabic languages and the way which documents are saved in the Unicode Standard, the information is hidden in Unicode text documents. This method has a good hiding capacity... 

Decision making is the process of finding the best option among the feasible alternatives. In classical multiple criteria decision making (MCDM) methods, the ratings and the weights of the criteria are known precisely. Owning to vagueness of the decision data, the crisp data are inadequate for real-life situations. Since human judgments including preferences are often vague and cannot be expressed by exact numerical values, the application of fuzzy concepts in decision making is deemed to be relevant. Here, we apply a new distance formula to compute the standard deviation of fuzzy data to achieve crisp data by normalization. There is a flexibility to consider various fuzzy values as...