Sharif Digital Repository

In this paper, nano/microstructured-conducting polypyrrole has been prepared on Cu/Au interdigital electrode surfaces by using constant potential amperometry technique. The Fe(II) ions were used as catalyst and X = ClO4 -, pTs-, Cl-, TCA-, DS-, DBS- was implemented as anion dopants. The morphologies of the films were investigated by field emission scanning electron microscope. A remarkable dependence was observed between the type of anion dopant and the morphology of polypyrrole (PPy). The sensing behavior of the PPy-X sensor has been studied toward acetone, methanol, ethanol, 1-propanol, 2-propanol, nitromethane, propylamine, pyridine, and gas mixtures of aliphatic alcohols. The responses... 

Connections have very important role in pre-cast concrete structures, especially in seismic zones, and grout connections increase strength and resistance of pre-cast concrete structures for lateral forces. High performance grout connections (HPGC) provide new opportunities to design cost-effective pre-cast concrete structures. HPGC have been proposed to decrease cost of insulation, erection and crane cost of pre-cast concrete structures and to overcome weakness of traditional pre-cast concrete structure connections .This research focuses on properties of grout materials properties which produced in Iran and the effect of propylene fiber on the performance of grout connection. In the first... 

We have investigated the water permeation through carbon nanotube (CNT) membranes as a model of peptide nanotube channels (PNCs). The effect of different charge configured CNTs which tailored based on some artificial ion channels on the water permeation through the channels have been studied. In addition, the temperature dependence of the permeation has been investigated. We have found that there is a jump in the permeation which is somehow related to the characteristics of each channel and the temperature of this permeation jump changes according to the channel configuration. Our investigation on the channels shows that the temperature at which the permeation jump occurs is related to the... 

Original scientific paper Developing a model for citizens' satisfaction with public services is one of the effective factors for improvement of service quality. In recent years, many studies have been carried out to identify a model for citizens' satisfaction with public sector services. In the structure of the presented models in the literature, one of the most important issues regarding organizations giving public services is identification of service scopes that have the most impact on citizens' satisfaction. This paper aims to develop a model to identify citizens' satisfaction status with public services. To do so, first, key factors influencing citizens' satisfaction with public... 

We study the variety of Löb algebras, the algebraic structures associated with Formal Propositional Calculus. Among other things, we show that there exist only two maximal intermediate logics in the lattice of intermediate logics over Basic Propositional Calculus. We introduce countably many locally finite sub-varieties of the variety of Löb algebras and show that their corresponding intermediate logics have the interpolation property. Finally, we characterize all chain basic algebras with empty set of generators, and show that there are continuum many such chain basic algebras  

Cryogenic technologies not only improve the performance of interconnects but also the performance of transistors and consequently drivers and repeaters. Although in cryogenically cooled integrated circuits the local temperature of interconnects and transistors may be as low as 50 K, it may easily reach to 600 K in high-temperature chips. In this brief, we investigated the impact of temperature on the delay of local, intermediate, unit-repeater-inserted (URI), and cascaded repeater-inserted (CRI) global copper interconnects for minimum technology node with available transistor model (32-nm technology). Our results show that temperature variation of driver resistance could change the delay of... 

This paper presents a design methodology for class-J monolithic microwave integrated circuit (MMIC) power amplifiers (PAs). Theoretical derivations of optimum load impedances, output power, efficiency, and maximum bandwidth are described in presence of nonlinear drain-source resistance of transistors (RDS). A procedure is developed for ideal transistor sizing where transistors are concurrently stabilized and sized to achieve the maximum power-added efficiency (PAE). A 3.5-7 GHz, 0.5-W class-J PA is implemented in a 0.1-μm AlGaAs-InGaAs pHEMT technology to check the accuracy of the proposed approach. With chip dimensions of 1.57 × 1.29 mm2, the PA achieves 56% average PAE over the frequency... 

The performance of gigascale integration chips improves by cryogenic technologies such as subambient cooling. In these conditions, interconnects may perform at temperatures as low as 50 K. However, the local temperature of interconnects could easily be as high as 600 K at high-temperature chips. In this brief, we investigated the impact of temperature on delay of local, intermediate, and global interconnects of International Technology Roadmap for Semiconductors Node 2024. This is done for different values of interconnect width and length, nanotube diameter, and percentage of metallic carbon nanotubes (CNTs) in a grown bundle. Results are compared with those of copper counterpart. We showed... 

With increasing use of e-banking system in Iranian banking sector, ignoring the issue of fraud in the system will be very costly for banks and e-banking customers. Fraud in e-banking is due to some security problems (such as weakness in access control systems and inadequate internal control). So, identifying success factor in fraud prevention in ebanking can be useful for e-banking system developers to improve these systems security. In this paper we have tried to identify and rank these success factors for fraud prevention in e-banking systems. For this purpose, we first review the literature to find potential factors, then identified factors were weighted by using fuzzy group multi... 

We study basic propositional logic (BPC) augmented with the law of the weak excluded middle (WEM), i.e. BPW = BPC+WEM. We show that the variety of the algebraic models of BPW is canonical, and its Kripke completeness is proved via cononicity. Moreover, it is also proved that BPW has the finite model property and is decidable. It is shown that BPC and BPW have the same behaviour on the ˔-free formulas and that CPC and BPW have the same behaviour on the negated formulas. © The Author(s) 2018. Published by Oxford University Press. All rights reserved  

This paper aims to present a novel accurate moving object detection method based on the conditional random field (CRF) for high efficiency video coding/H.265 compressed domain video sequences. For each block, the number of consumed bits, motion vectors (MVs), and partitioning modes for a given block is extracted from the compressed bitstream. After removing outlier MVs, compensating MVs are assigned to the I-blocks based on their neighboring blocks. The information, such as MV, partitioning mode, and bit consumption, is used in the potential functions of a CRF model which is updated for every frame to detect the objects. Then, a number of standard test video sequences are used to verify the... 

Emulsion flooding is a promising method for enhanced oil recovery (EOR). The static and dynamic behavior of the emulsions is greatly influenced by the nature of the applied surfactant. In this work, the effect of fatty acids, as natural surface-active agents, and their chain length on the emulsion behavior was investigated in both bulk and porous media. A panel of the fatty acids with different chain lengths (6 < C < 18) was applied at constant concentration and pH. Upon the static stability tests, emulsion stability at the optimum value of chain length (C14) was increased by two orders of magnitude. Under the optimal condition, the hydrogen bonding between dissociated and undissociated... 

In this paper, performance of class-J mode power amplifiers (PAs) is studied when a second-harmonic voltage component is added to the input node of the device. Theoretical formulations for the optimum load impedances, output power, and drain efficiency are developed for this case, and it is shown that the inclusion of a proper second-harmonic voltage at the gate node of the transistor improves the drain efficiency and output power. To check the accuracy of the theoretical analyses and the simulation results, a proof-of-concept 1-GHz 0.65-W class-J PA is fabricated in a 0.25-μm AlGaAs-InGaAs pHEMT technology. The nonlinear gate-source capacitor (CGS) of the transistor is employed to generate... 

This paper presents the design and implementation of a distributed class-J power amplifier (DJPA) in a 0.25-μm AlGaAs-InGaAs pHEMT technology. Class-J mode of operation is introduced in design of distributed power amplifiers (DPAs) to achieve high power added efficiencies (PAEs) over wide frequency ranges. Extensive load-pull (LP) and source-pull (SP) simulations are performed to show that class-J PAs are less sensitive to proper termination of higher order harmonics, and high PAE and output power can be obtained even if the second, third, fourth, and fifth harmonics comprise a real impedance. This is essential in DPAs as the higher order harmonics of the frequencies at lower side of the... 

By increasing the complexity of system on a chip (SoC) formal equivalence checking has become more and more important and a major economical issue to detect design faults at early stages of the design cycle in order to reduce time-to-market as much as possible. However, lower level methods such as BDDs and SAT solvers suffer from memory and computational explosion problems to match sizes of industrial designs in formal equivalence verification. In this paper, we describe a hybrid bit- and word-level canonical representation called Linear Taylor Expansion Diagram (LTED) [1] which can be used to check the equivalence between two descriptions in different levels of abstractions. To prove the... 

Low salinity waterflooding (LSWF) is a process in which by lowering the ionic strength and/or manipulation of the composition of the injection water, the long term equilibrium in oil/brine/rock system is disturbed to reach a new state of equilibrium through which the oil production will be enhanced due to fluid/fluid and/or rock/fluid interactions. In spite of recent advances in the simulation of the LSWF at core scale and beyond, there are very few works that have modelled and simulated this process at the pore scale specially using direct numerical simulation (DNS). As a result the effects of wettability alteration and/or Interfacial Tension (IFT) change on the distribution of the phases... 

Using our recently developed model, for the first time in the literature, the effect of fluid/fluid and rock/fluid interactions on the performance of Low Salinity Waterflooding (LSWF, as an Enhanced Oil Recovery process) at pore-doublet scale is investigated. The model is incorporated into OpenFOAM and both the Navier-Stokes equation for oil/water two-phase flow and the advection-diffusion equation for ion transport (at both fluid/fluid and rock/fluid interface) are solved via direct numerical simulation (DNS). The model is validated against imbibition and drainage pore-doublet experiments reported in the literature, and then applied to investigate the sole effect of wettability alteration... 

This study presents a comprehensive framework for evaluating renewable and non-renewable power plants' performance using the Life Cycle Analysis (LCA) and emergy analysis. The emergy analysis is used to consider the free ecosystem services in the sustainability of the systems as a supplement to the LCA. The results indicate that the wind and photovoltaic power plants have the best performance in terms of the LCA analysis, while the wind and combined cycle power plants have the highest emergy sustainability index. The best scenario is chosen under a two-objective optimization problem, including the single score and emergy sustainability as objective functions. Here, the wind power plant is... 

We study the variety of Löb algebras, the algebraic structures associated with formal prepositional calculus. Among other things, we prove a completeness theorem for formal prepositional logic with respect to the variety of Löb algebras. We show that the variety of Löb algebras has the weak amalgamation property. Some interesting subclasses of the variety of Löb algebras, e. g. linear, faithful and strongly linear Löb algebras are introduced. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA