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A Low area overhead NBTI/PBTI sensor for SRAM memories
, Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 25, Issue 11 , 2017 , Pages 3138-3151 ; 10638210 (ISSN) ; Rohbani, N ; Miremadi, S. G ; Sharif University of Technology
2017
Abstract
Bias temperature instability (BTI) is known as one serious reliability concern in nanoscale technologies. BTI gradually increases the absolute value of threshold voltage (Vth) of MOS transistors. The main consequence of Vth shift of the SRAM cell transistors is the static noise margin (SNM) degradation. The SNM degradation of SRAM cells results in bit-flip occurrences due to transient faults and should be monitored accurately. This paper proposes a sensor called write current-based BTI sensor (WCBS) to assess the BTI-aging state of SRAM cells. The WCBS measures BTI-induced SNM degradation of SRAM cells by monitoring the maximum write current shifts due to BTI. The observations show that the...
Effects of the design parameters of multimodel adaptive control on the performance of a flexible transmission system
, Article International Journal of Adaptive Control and Signal Processing ; Volume 15, Issue 3 , 2001 , Pages 335-352 ; 08906327 (ISSN) ; Landau, I. D ; Motee, N ; Sharif University of Technology
2001
Abstract
Design parameters selection in the multimodel adaptive control based on switching and tuning will be investigated. Some design parameters like number of fixed and adaptive models, forgetting factor and minimum time delay between switchings will be considered. A recently developed parameter adaptation algorithm based on closed-loop output error will be compared with the classical least-squares prediction error algorithm in the multimodel adaptive control. The effects of these parameters on the performance in tracking and in regulation of a flexible transmission system will be studied via several simulation examples
A thermodynamic-based large deformation viscoplastic constitutive relationship for asphalt concrete compaction
, Article International Journal of Solids and Structures ; Volume 165 , 2019 , Pages 192-216 ; 00207683 (ISSN) ; Darabi, M. K ; Tabatabaee, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
This research proposes a large deformation, time-dependent viscoplastic constitutive relationship to enhance the prediction of the compaction degree of asphalt concrete materials under laboratory and field conditions. A large-deformation thermodynamic-based framework is presented. The Helmholtz free energy and rate of energy dissipation functions were assumed to derive rate-dependent constitutive relationships to relate multi-axial state of stresses to the recoverable and non-recoverable deformation response of asphalt concrete during compaction. A straightforward method that allows the calibration of the proposed model against laboratory compaction data (e.g., data from Superpave Gyratory...
Reducing traffic congestion and increasing sustainability in special urban areas through one-way traffic reconfiguration
, Article Transportation ; 2021 ; 00494488 (ISSN) ; Ghadirifaraz, B ; Shetab Boushehri, S. N ; Hosseininasab, S. M ; Rafiei, N ; Sharif University of Technology
Springer
2021
Abstract
In the contemporary sustainable urban set up, one of the critical issues adversely affecting the quality of life in urban areas and inflicting immense costs on cities is traffic congestion. Traffic congestion is an outgrowth of increased traffic flow in certain locations of large cities. Recently, urban decision-makers and transportation planners resort to one-way traffic system as an effective traffic management strategy, which has a profound effect on reducing traffic congestion and improving traffic flow, leading to urban sustainability. In the present paper, the authors endeavored to develop a novel methodological framework based on optimization techniques in order to mitigate traffic...
Reducing traffic congestion and increasing sustainability in special urban areas through one-way traffic reconfiguration
, Article Transportation ; Volume 49, Issue 1 , 2022 , Pages 37-60 ; 00494488 (ISSN) ; Ghadirifaraz, B ; Shetab Boushehri, S. N ; Hosseininasab, S. M ; Rafiei, N ; Sharif University of Technology
Springer
2022
Abstract
In the contemporary sustainable urban set up, one of the critical issues adversely affecting the quality of life in urban areas and inflicting immense costs on cities is traffic congestion. Traffic congestion is an outgrowth of increased traffic flow in certain locations of large cities. Recently, urban decision-makers and transportation planners resort to one-way traffic system as an effective traffic management strategy, which has a profound effect on reducing traffic congestion and improving traffic flow, leading to urban sustainability. In the present paper, the authors endeavored to develop a novel methodological framework based on optimization techniques in order to mitigate traffic...
The lake urmia environmental disaster in Iran: a look at aerosol pollution
, Article Science of the Total Environment ; Volume 633 , 2018 , Pages 42-49 ; 00489697 (ISSN) ; Khaghani, A ; MacDonald, A. B ; Nguyen, P ; Karimi, N ; Heidary, P ; Karimi, N ; Saemian, P ; Sehatkashani, S ; Tajrishy, M ; Sorooshian, A ; Sharif University of Technology
2018
Abstract
Lake Urmia (LU) once was the second largest hypersaline lake in the world, covering up to 6000 km2, but has undergone catastrophic desiccation in recent years resulting in loss of 90% of its area and extensive coverage by playas and marshlands that represent a source of salt and dust. This study examines daily Aerosol Optical Depth (AOD) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) between 2001 and 2015 over northwestern Iran, which encompasses LU. Intriguingly, salt emissions from the LU surface associated with ongoing desiccation do not drive the study region's AOD profile, whereas pollution transported from other regions and emissions around LU are more important....
Development of a stress-mode sensitive viscoelastic constitutive relationship for asphalt concrete: experimental and numerical modeling
, Article Mechanics of Time-Dependent Materials ; 2016 , Pages 1-35 ; 13852000 (ISSN) ; Tabatabaee, N ; Jahanbakhsh, H ; Jahangiri, B ; Sharif University of Technology
Springer Netherlands
2016
Abstract
Asphalt binder is responsible for the thermo-viscoelastic mechanical behavior of asphalt concrete. Upon application of pure compressive stress to an asphalt concrete specimen, the stress is transferred by mechanisms such as aggregate interlock and the adhesion/cohesion properties of asphalt mastic. In the pure tensile stress mode, aggregate interlock plays a limited role in stress transfer, and the mastic phase plays the dominant role through its adhesive/cohesive and viscoelastic properties. Under actual combined loading patterns, any coordinate direction may experience different stress modes; therefore, the mechanical behavior is not the same in the different directions and the asphalt...
Development of a stress-mode sensitive viscoelastic constitutive relationship for asphalt concrete: experimental and numerical modeling
, Article Mechanics of Time-Dependent Materials ; Volume 21, Issue 3 , 2017 , Pages 383-417 ; 13852000 (ISSN) ; Tabatabaee, N ; Jahanbakhsh, H ; Jahangiri, B ; Sharif University of Technology
Springer Netherlands
2017
Abstract
Asphalt binder is responsible for the thermo-viscoelastic mechanical behavior of asphalt concrete. Upon application of pure compressive stress to an asphalt concrete specimen, the stress is transferred by mechanisms such as aggregate interlock and the adhesion/cohesion properties of asphalt mastic. In the pure tensile stress mode, aggregate interlock plays a limited role in stress transfer, and the mastic phase plays the dominant role through its adhesive/cohesive and viscoelastic properties. Under actual combined loading patterns, any coordinate direction may experience different stress modes; therefore, the mechanical behavior is not the same in the different directions and the asphalt...
An optimal fractional order controller for an AVR system using particle swarm optimization algorithm
, Article 2007 Large Engineering Systems Conference on Power Engineering, LESCOPE'07, Montreal, QC, 10 October 2007 through 12 October 2007 ; January , 2007 , Pages 244-249 ; 9781424415830 (ISBN) ; Zamani, M ; Sadati, N ; Parniani, M ; Sharif University of Technology
2007
Abstract
Application of Fractional Order PID (FOPID) controller to an Automatic Voltage Regulator (AVR) is presented and studied in this paper. An FOPID is a PID whose derivative and integral orders are fractional numbers rather than integers. Design stage of such a controller consists of determining five parameters. This paper employs Particle Swarm Optimization (PSO) algorithm to carry out the aforementioned design procedure. A novel cost function is defined to facilitate the control strategy over both the time-domain and the frequencydomain specifications. Comparisons are made with a PID controller from standpoints of transient response, robustness and disturbance rejection characteristics. It is...
Development of an optimal process for friction stir welding based on GA-RSM hybrid algorithm
, Article Frattura ed Integrita Strutturale ; Volume 12, Issue 44 , April , 2018 , Pages 106-122 ; 19718993 (ISSN) ; Berto, F ; Karimi, N ; Ghoreishi, S. M. N ; Fakoor, M ; Mokari, M ; Sharif University of Technology
Gruppo Italiano Frattura
2018
Abstract
Performance of Friction Stir Welding (FSW) as a solid-state process is approved in several engineering applications, especially aluminum industries. Identification of mechanical behavior of the associated welded zone is necessary due to these extensive applications of FSW. In this study, considering the effect of rotational and forward speed of welding tool on the mechanical properties of welded region, a hybrid optimization method based on combination of Genetic Algorithm (GA) and Response Surface Method (RSM) named here as GA-RSM is proposed to achieve maximum tensile and ultimate strength. The results of GA-RSM are validated by per-forming necessary experimental tests on two wide-used...
Wettability alteration and oil recovery by spontaneous imbibition of low salinity brine into carbonates: Impact of Mg2+, SO4 2− and cationic surfactant
, Article Journal of Petroleum Science and Engineering ; Volume 147 , 2016 , Pages 560-569 ; 09204105 (ISSN) ; Al-Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
Elsevier B.V
2016
Abstract
A large amount of the discovered oil reserves are reserved in carbonate formations, which are mostly naturally fractured oil-wet. Wettability alteration towards more water-wet state reduces the capillary barrier, hence improving the oil recovery efficiency in such reservoirs. In this study, wettability alteration towards favorable wetting state was investigated by combining modified low salinity brine with surfactant during water flooding. The diluted brine was modified by increasing the concentration of Mg2+ and SO4 2−, individually as well as both ions in combination. Different brine formulations were tested experimentally through the observations of contact angle measurements and...
Mechanistic study of wettability alteration of oil-wet calcite: The effect of magnesium ions in the presence and absence of cationic surfactant
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 482 , October , 2015 , Pages 403-415 ; 09277757 (ISSN) ; Al Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
Elsevier
2015
Abstract
Over 60% of the world's discovered oil reserves are held in carbonate reservoirs, which are mostly naturally fractured. Conventional water flooding results in low oil recovery efficiency in these reservoirs as most of them are oil-wet. On account of negative capillary forces, injected brine cannot penetrate simply into an oil-wet matrix of fractured formations to force the oil out. Wettability alteration of the rock surface to preferentially more water-wet state has been extensively studied using both smart water and surfactants separately. This study aims to study the effects of Mg2+ as one of the most important wettability influencing ions on the wetting properties of oil-wet carbonate...
Impact of sulfate ions on wettability alteration of oil-wet calcite in the absence and presence of cationic surfactant
, Article Energy and Fuels ; Volume 30, Issue 2 , 2016 , Pages 819-829 ; 08870624 (ISSN) ; Al-Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
American Chemical Society
2016
Abstract
The modification of the surface wetting characteristics in fractured oil-wet carbonate reservoirs, by reversing wettability from oil-wet to water-wet, leads to improved oil recovery. However, in order to obtain a successful oil recovery process, it is crucial to understand the active mechanisms of wettability alteration. This study looks at the effect of sulfate ions as one of the most promising wettability influencing ions on the wetting properties of oil-wet calcite; the effect is studied both with and without the presence of cationic surfactant and possible mechanisms of wettability alteration are explored. A number of analytical techniques were utilized to analyze the mineral surface...
Constitutive modeling of hardening-relaxation response of asphalt concrete in cyclic compressive loading
, Article Construction and Building Materials ; Volume 137 , 2017 , Pages 169-184 ; 09500618 (ISSN) ; Tabatabaee, N ; Jahangiri, B ; Darabi, M. K ; Sharif University of Technology
2017
Abstract
Cyclic loading on asphalt concrete materials with a longer relaxation time and lower remaining stress lead to higher viscoelastic strain recovery. Consequently, more aggregate reorientation occurs and the rate of viscoplastic strain increases in subsequent cycles. The present study proposes a hardening relaxation constitutive relationship (fHR) as a function of accumulated recovered viscoelastic strain εrve based on experimental observation. This model captures the initiation and evolution of hardening-relaxation during the relaxation time and/or stress reduction under cyclic loading. The model was then coupled with viscoelastic, viscoplastic and viscodamage constitutive relationships. The...
Deeper neural network models better reflect how humans cope with contrast variation in object recognition
, Article Neuroscience Research ; Volume 192 , 2023 , Pages 48-55 ; 01680102 (ISSN) ; Ebrahimpour, R ; Bagheri, N ; Karimi Rouzbahani, H ; Sharif University of Technology
Elsevier Ireland Ltd
2023
Abstract
Visual inputs are far from ideal in everyday situations such as in the fog where the contrasts of input stimuli are low. However, human perception remains relatively robust to contrast variations. To provide insights about the underlying mechanisms of contrast invariance, we addressed two questions. Do contrast effects disappear along the visual hierarchy? Do later stages of the visual hierarchy contribute to contrast invariance? We ran a behavioral experiment where we manipulated the level of stimulus contrast and the involvement of higher-level visual areas through immediate and delayed backward masking of the stimulus. Backward masking led to significant drop in performance in our visual...
Photovoltaic parameters and stability study of HTM-free mixed-cation perovskite solar cells by incorporating additives to absorbing layers
, Article Journal of Materials Science: Materials in Electronics ; Volume 31, Issue 9 , 2020 , Pages 7123-7132 ; Behjat, A ; Karimi Zarchi, A ; Taghavinia, N ; Mirjalili, B. F ; Sharif University of Technology
Springer
2020
Abstract
In this study, quick route-coating is practiced to substitute methyl ammonium (MA) cation with formamidinium (FA) at different ratios. Through optimizing the MA:FA ratio, a maximum power conversion efficiency (PCE) of 8.31% is achieved for holes transporting material-free MA0.8FA0.2PbI3 mixed PSCs with the JSC of 19.02 mA/cm2, VOC of 0.859 V and FF of 50.88%. Then, to improve the performance, stability and carrier transport dynamic, various additives (PVA, PVP, PEG and EC) are incorporated into the perovskite layer. The treatment of perovskites with additives has proved to cause significant changes in the surface roughness, charge accumulation, charge transport, charge transport resistance,...
Objective measurement of inferior-directed stiffness in glenohumeral joint using a specially designed robotic device in healthy shoulders; within- and between-session reliability
, Article Journal of Biomechanics ; Volume 127 , 2021 ; 00219290 (ISSN) ; Mirbagheri, A. R ; Hosseini, R ; Shadmehr, A ; Karimi, N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Clinical assessment of capsuloligamentous structures of the glenohumeral joint has been qualitative and subjective in nature, as demonstrated by limited intra- and inter-rater reliability. Robotic devices were utilized to develop a clinically objective measurement technique for glenohumeral joint stiffness. The purpose of this study was to quantify the amount of inferior-direction stiffness of the glenohumeral joint using a safe clinical device in the asymptomatic individuals, and to determine between trial and between session reliability of the robotic device. Twenty healthy subjects were recruited via convenience sampling. Inferior-directed translation and applying force were measured...
Reduction of sensor population in a camera sensor network
, Article 2008 International Symposium on Telecommunications, IST 2008, Tehran, 27 August 2008 through 28 August 2008 ; 2008 , Pages 349-353 ; 9781424427512 (ISBN) ; Samavi, S ; Ashori, M ; Karimi, N ; Fotohi, M ; Kasiri, K ; Sharif University of Technology
2008
Abstract
The problem of surveillance for intrusion detection in a camera sensor network is addressed in this paper. In order to save limited resources, a sensing task should involve just the right number of sensors. For a wide enough coverage area random and uniform distribution can be applied. We propose a novel method which allows reduction of number of sensors and guarantees a desired surveillance against aerial intrusion. Enhancement of the method is also offered to further reduce the number of sensors and improve the performance. ©2008 IEEE
A novel approach for optimal design of a rover mechanism
, Article Journal of Intelligent and Robotic Systems: Theory and Applications ; Volume 44, Issue 4 , 2005 , Pages 291-312 ; 09210296 (ISSN) ; Pishkenari, H. N ; Gaskarimahalle, A. L ; Mahboobi, S. H ; Karimi, R ; Sharif University of Technology
2005
Abstract
This article presents an overview of the mechanical design and fabrication of a Rescue Robot (CEDRA) for operation in unstructured environments. In order to obtain an appropriate mechanism for climbing the stairs, a novel method has been developed. In this kinematics-based approach we don't need to perform any dynamic analysis which is highly complicated and time consuming for most rovers. According to the essential characteristics needed for rovers, two objective functions were defined. We have shown that the new mechanism performs better on rough terrains than the previous well-known mechanism widely used in the Mars rovers. Moreover the design parameters are optimized by means of Genetic...
Optimal design and fabrication of "CEDRA" rescue robot using genetic algorithm
, Article 2004 ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Salt Lake City, UT, 28 September 2004 through 2 October 2004 ; Volume 2 A , 2004 , Pages 541-548 ; Pishkenari, H. N ; Gaskarimahalle, A. L ; Mahboobi, S. H ; Karimi, R ; Sharif University of Technology
American Society of Mechanical Engineers
2004
Abstract
This article presents an overview of the mechanical design features, fabrication and control of a Rescue Robot (CEDRA) for operation in unstructured environments. As a preliminary step, the essential characteristics of a robot in damaged and unstable situations have been established. According to these features and kinematical equations of the robot, design parameters are optimized by means of Genetic Algorithm. Optimum parameters are then utilized in construction. Upon fabrication, this unit has been tested in clean laboratory environment, as well as, ill-conditioned arenas similar to earthquake zones. The obtained results have been satisfactory in all aspects, and improvements are...