Sharif Digital Repository

Radio frequency identification (RFID) technology is a prominent technology which has been used in most authentication and identification applications. Above all, recently RFID systems have got more attention as an interesting candidate to implement in the internet of things systems. Although RFID systems provide useful and interest services to users, they can also threat the security and the privacy of the end-users. In order to provide the security and the privacy of RFID users, different authentication protocols have been proposed. In this study, we analyze the privacy of three RFID authentication protocols that proposed recently. For our privacy analysis, we use a formal RFID privacy... 

We obtain an exact analytical expression for magnetoresistance using noncommutative geometry and quantum groups. We then show there is a deep relationship between magnetoresistance and the quantum group suq(2), from which we understand the quantum interpretation of the quantum corrections to the conductivity  

We obtain an exact analytical expression for magnetoresistance using noncommutative geometry and quantum groups. Then we will show that there is a deep relationship between magnetoresistance and the quantum group su q(2), from which we understand the quantum interpretation of the quantum corrections to the conductivity. © 2003 Elsevier B.V. All rights reserved  

LLC resonant converter has been widely used in dcdc converters. In this paper, optimum dead-time and maximum switching frequency of a wide-adjustable-range LLC resonant converter are investigated for realizing the zero voltage switching (ZVS) operation even under the worst-case conditions. Analyses demonstrate that these parameters depend on the converter inductance ratio and ratio of the converter resonant capacitor and the effective capacitance appeared in parallel with the drainsources of the power MOSFETs. The necessary dead time for realizing the ZVS operation can be minimized by choosing the normalized maximum switching frequency, properly. Using the dead-time optimum value, soft... 

LLC-LC resonant converter is a suitable circuit topology to design switched-mode power supplies for wide-output-voltage and wide-output-load applications. In this paper, a design procedure is introduced to optimize this converter. Unlike soft switching techniques for pulse width modulated converters, which usually apply an active auxiliary circuit to reduce switching losses and EMI, in the proposed converter, not only such circuits are not used, but also all of the parasitic elements are merged to the converters main components. Zero-voltage switching (ZVS) operation is realized for all power devices under all operating conditions. Thus, this converter is a suitable choice for... 

LLC resonant converter is one of the most suitable circuit topologies that have been introduced for designing constant output voltage switched-mode power supplies. In this paper, a design procedure is introduced for using this converter as a wide output range voltage source. Unlike constant output voltage applications which need small converter inductance ratio and narrow switching frequency variations, for wide output range applications, large values of these parameters are needed simultaneously and should be optimized. Instead of minimizing the components stresses, leading to a great value of the inductance ratio, proper choice of the converter parameters resulting in a smaller inductance... 

LLC resonant converter with significant resonant inductance is proposed for designing an adjustable wide-range regulated voltage source. Large resonant inductance increases output voltage adjustment range and conversion efficiency, particularly at light loads. Soft switching is achieved for all power devices under all operating conditions by choosing the dead time and maximum switching frequency properly and operating in the converter's inductive region. Using a power-factor-correction (PFC) converter reduces the resonant converter's output voltage dependence to the variations of the main ac input voltage. Thus, the compensation of the load variations and the wide-range adjustment of the... 

LLC resonant converter has been used widely as dc-dc converter for achieving constant dc voltage. In this paper, an LLC resonant converter, by adding an inductance to its conventional topology and considering the rectifying stage stray inductances, is proposed for an adjustable wide range regulated current source (20-200 A dc) for using as ion implanter's filament power supply. The additional inductor increases output current adjustment range and efficiency, especially at light loads. Transformer's leakage inductances and rectifying stage stray inductances have been considered. Because of these inductances, the rectifier stage always works in continuous conduction mode, and its conduction... 

Introduction: Among several surgical treatments, the use of transplantation of epidermal cultured melanocytes or melanocytes–keratinocytes cell suspension has gained many researchers and dermatologists' attention as a new technique for the treatment of vitiligo. The present study aimed to transplant autologous epidermal melanocytes–keratinocytes cell suspension for the treatment of vitiligo. Methods: In this study, 15 volunteer patients aged between 18 and 45 years old were studied. The autologous melanocytes–keratinocytes cell suspension was then transplanted to the region after dermabrasion. The included patients were evaluated by VisioFace, MPA9, and Skin Scanner-DUB once before and 1, 2,... 

In the last decade, various types of RFID security schemes have been proposed which have tried to provide all security and privacy requirements of end-users. In this paper, we cryptanalyze two new-found key exchange and key agreement security schemes which are proposed by Zhang et al. and Kim in 2012 and 2013 respectively. We present the reveal secret parameter, tag impersonation and traceability attacks on Zhang et al's protocol with success probability '1', and also we show that an attacker can impersonate the tag and the reader of Kim's protocol both with success probabilities '1/4'. We also present some modifications on the structure of studied schemes and propose two modified schemes... 

The disasters caused by epidemic outbreaks is different from other disasters due to two specific features: their long-term disruption and their increasing propagation. Not controlling such disasters brings about severe disruptions in the supply chains and communities and, thereby, irreparable losses will come into play. Coronavirus disease 2019 (COVID-19) is one of these disasters that has caused severe disruptions across the world and in many supply chains, particularly in the healthcare supply chain. Therefore, this paper, for the first time, develops a practical decision support system based on physicians' knowledge and fuzzy inference system (FIS) in order to help with the demand... 

Static recrystallization and microstructural changes in austenitic stainless steel 304L were studied. The rolling experiments at 200 °C were carried out, and then, annealing treatment was made at temperatures ranging between 500 and 830 °C. A model was also developed to simulate the kinetics of non-isothermal recrystallization within the rolled steel. The distribution of plastic strains during rolling was predicted utilizing an elastic–plastic finite element formulation performed in ABAQUS/Explicit, while the predicted results were used to generate the as-rolled microstructure and to estimate the stored energy. Finally, microstructural–thermal model based on cellular automata was developed... 

In this work, non-isothermal annealing of cold-rolled 304L austenitic stainless steel was studied at temperatures ranging between 400 and 800 °C. In the first place, a dual-phase structure containing work-hardened austenite and strain-induced martensite was produced by means of multi-pass plate rolling, and then, the deformed steel was subjected to annealing heat treatments. To determine the distribution of stored strain energy in the rolling operations, an elastic–plastic finite-element modeling was conducted. Afterwards, an artificial neural network technique was coupled with the thermal-cellular automata model for prediction of martensite reversion, temperature history, and... 

Although there have been numerous studies of self-efficacy and collective efficacy in different contexts, little attention has been paid to proxy efficacy. In this article we propose that a person's self-efficacy may be related to proxy efficacy when achievement of personal goals is related to the performance of the proxy on the person's behalf. We argue this is important in team leadership. We further propose that the extent to which team members believe their leaders efficacious as their proxies may affect team processes and effectiveness. A team level construct, namely team proxy efficacy for the leader, referring to a shared proxy efficacy belief for the team leader, is also proposed.... 

Organizational change has become complex and challenging, and employee attitudes and beliefs toward change are even more important. This article proposes a theoretical framework on how authentic leadership may influence followers’ change-oriented attitudes, beliefs, and behaviors through follower psychological resources including hope, trust, optimism, self-efficacy, and resilience, which influence readiness for change and change implementation. We maintain that an authentic leader’s behavior can influence his or her followers’ change-oriented behaviors in participation in decision-making processes and change initiatives, organization citizenship behavior, organizational learning processes,... 

Few studies have been conducted about team members’ individual beliefs of their team’s collective efficacy (personal collective efficacy). We argue that this individual belief is a motivational factor for teamwork along with self-efficacy for teamwork. This study investigated relationships between personal collective efficacy, self-efficacy for teamwork, collective orientations and perceptions of self in relation to other team members. In addition, relationships between personal collective efficacy and team members’ perceptions of team activities namely evaluating and integrating were explored. Multilevel analysis was employed in order to account for team level variation when testing... 

Background. Although the relationship between collective efficacy and group performance has been frequently investigated, a few studies have investigated the development of collective efficacy. Aim. This paper proposes some determinants of collective efficacy in small university groups. Group level hypotheses and research questions relating collective efficacy to collective cognition activities, task interdependence, self-efficacy for group work, and collective orientation were posited. Sample. The sample comprised 145 university students in 40 work-groups. Method. A two-phase longitudinal design was employed in the context of university student groups. All groups were required to perform... 

In this paper concurrent design of Schottky diode based limiter and low noise amplifier (LNA), based on noise matching, is investigated to achieve minimum noise figure (NF) of the receiver chain. In design procedure of the LNA, the noise figure is minimum, gain at central frequency is 14.5 dB, and limiter structure tolerates up to 5 W continuous wave input power. In the proposed concurrent design, a pass-band filter is applied at the LNA output to attenuate undesired out-of-band signals. In the proposed design, the limiter-LNA is implemented with a 0.25 µm gate length AlGaAs/InGaAs pHEMT process. Measured noise figure of chain is 2.7 dB and average gain over 8.5–9.5 GHz frequency range and... 

In this paper concurrent design of Schottky diode based limiter and low noise amplifier (LNA), based on noise matching, is investigated to achieve minimum noise figure (NF) of the receiver chain. In design procedure of the LNA, the noise figure is minimum, gain at central frequency is 14.5 dB, and limiter structure tolerates up to 5 W continuous wave input power. In the proposed concurrent design, a pass-band filter is applied at the LNA output to attenuate undesired out-of-band signals. In the proposed design, the limiter-LNA is implemented with a 0.25 µm gate length AlGaAs/InGaAs pHEMT process. Measured noise figure of chain is 2.7 dB and average gain over 8.5–9.5 GHz frequency range and... 

The novel idea of the Hydromagnetic Micropump and Flow Controller (HMFC) is used in this paper to construct a laboratory setup capable of bidirectional pumping and controlling the flow in microtubes. A laboratory setup, which contains no moving parts, is integrated with a pressure-driven flow setup to make the presented HMFC device. The device operation is based on controllable motion of magnetic particles, added to the carrier fluid, caused by the magnetic field, produced by solenoids located just next to the microtube. The magnitude of these forces is proportional to the strength and gradient of magnetic field which, in turn, is related to the electrical current and arrangement of the...