Loading...
Search for: temperature-variations
0.011 seconds
Total 45 records

    Effects of altitude and temperature on the performance and efficiency of turbocharged direct injection gasoline engine

    , Article Journal of Applied Fluid Mechanics ; Volume 12, Issue 6 , 2019 , Pages 1825-1836 ; 17353572 (ISSN) Motahari, S ; Chitsaz, I ; Sharif University of Technology
    Isfahan University of Technology  2019
    Abstract
    Iran is located at the high altitude region and has a diverse four season climate. The temperature difference of two locations at the same time reaches to 50° C. Therefore, the modern direct injection turbocharged engines are highly affected at this condition. This paper deals with the effects of temperature and pressure variations on the engine performance and fuel consumption of turbocharged gasoline direct injection engine. Ford ecoboost is selected for this study and the base experiments are performed at the sea level. At the next step, a comprehensive one-dimensional model of the engine is constructed in GT power and validated with experimental data. Validated model is implemented to... 

    Effects of altitude and temperature on the performance and efficiency of turbocharged direct injection gasoline engine

    , Article Journal of Applied Fluid Mechanics ; Volume 12, Issue 6 , 2019 , Pages 1825-1836 ; 17353572 (ISSN) Motahari, S ; Chitsaz, I ; Sharif University of Technology
    Isfahan University of Technology  2019
    Abstract
    Iran is located at the high altitude region and has a diverse four season climate. The temperature difference of two locations at the same time reaches to 50° C. Therefore, the modern direct injection turbocharged engines are highly affected at this condition. This paper deals with the effects of temperature and pressure variations on the engine performance and fuel consumption of turbocharged gasoline direct injection engine. Ford ecoboost is selected for this study and the base experiments are performed at the sea level. At the next step, a comprehensive one-dimensional model of the engine is constructed in GT power and validated with experimental data. Validated model is implemented to... 

    Fault Modeling of Transient Faults in Embedded Processors

    , M.Sc. Thesis Sharif University of Technology Tajik, Hossein (Author) ; Ejlali, Alireza (Supervisor)
    Abstract
    Many embedded processors are used in harsh environments and their behavior should be investigated against the incidence of common faults. Fault Injection is a prevalent method to do this investigation. Simulation-based fault injection is one of the most prominent forms of fault injection. A fault model is required to do simulation-based fault injection. Simulated faults should have the most similarity to the real faults. Temperature variation and in the extreme case thermal shock is one of the probable faults in harsh environment. In this thesis, we want to propose fault models for thermal shock in various abstraction levels, evaluate and compare these fault models and present methods to use... 

    Reliable Adaptive Wavelength Modulation for Optical Networks-on-Chip

    , M.Sc. Thesis Sharif University of Technology Karimi, Roshanak (Author) ; Hessabi, Shahin (Supervisor) ; Koohi, Somayyeh (Supervisor)
    Abstract
    Integrating hundreds of cores on a single chip necessitates high performance interconnection network. Due to great delay and power consumption of electrical networks in global connections, their use might be limited in future. Optical networks-on-chip are introduced recently as a proper alternative for electrical networks by providing high bandwidth, low latency, and low power consumption. Despite these outstanding advantages, optical component behavior is very sensitive to temperature fluctuations. Specifically, thermal variations affect refractive index of semiconductor, which in turn change resonating wavelength of micro-ring resonator. Therefore, the switch cannot operate properly and... 

    Thermal-aware Routing Algorithm in Fault-tolerant Optical Networks-on-Chip

    , M.Sc. Thesis Sharif University of Technology Erfani Jazi, Hamid Reza (Author) ; Koohi, Somayyeh (Supervisor)
    Abstract
    During the recent years, the emerging technology of photonic, on-chip communication has been widely explored to resolve the problems of traditional electrical communication in terms of performance and power consumption. Micro-Resonator (MR) as the photonic building block for optical comunication is very sensitive to temperature and process variation. Variation of resonance wavelength of a micro-resonator as a result of temperature fluctuations causes tremendous error for optical data routing through the waveguides, and reduce the reliability of network. A temperature-aware routing algorithm enables the network to tolerate fault and continue working properly. Temperature variation of MRs is a... 

    Fault Rate Modeling in Terms of Power Consumption and Thermal Variation in Optical Networks-on-Chip

    , M.Sc. Thesis Sharif University of Technology Abolhasani Zeraatkar, Alireza (Author) ; Koohi, Somayyeh (Supervisor)
    Abstract
    Global on chip communication becomes a critical power bottleneck in high performance many core architectures. The importance of power dissipation in networks-on-chip along with power reduction capability of on-chip nanophotonic interconnects has made optical network on chip a novel technology. Major advantages like high bandwidth, light speed latency and low power consumption, provide a promising solution for future of communications in many core architectures. However, the basic elements that are embedded in optical networks on chip are extremely temperature sensitive. This would lead to change in the physical characteristics of nanophotonic elements which may cause failure in network on... 

    A Study of Weather Change Impacts on Construction Projects in Iran

    , M.Sc. Thesis Sharif University of Technology Javadi Aghdam, Shayan (Author) ; Alvanchi, Amin (Supervisor)
    Abstract
    Several factors can cause an effect on the overall efficiency of construction projects, especially because most of these projects are being hold outdoors. Recognizing these factors can help the project to increase its efficiency and also help the managers and the schedule planners to set their aims more accurately. One of the most important factor which affects the project efficiency is the climate change and weather. The aim of this project is to help the planner and the main subject of this project is providing a guideline for the planners and managers of construction projects about the effects of weather and climate change on the schedule and the estimation of the budget of the project... 

    Low cost soft error hardened latch designs for nano-scale CMOS technology in presence of process variation

    , Article Microelectronics Reliability ; Volume 53, Issue 6 , June , 2013 , Pages 912-924 ; 00262714 (ISSN) Rajaei, R ; Tabandeh, M ; Fazeli, M ; Sharif University of Technology
    2013
    Abstract
    In this paper, two Low cost and Soft Error Hardened latches (referred to as LSEH1 and LSEH2) are proposed and evaluated. The proposed latches are fully SEU immune, i.e. they are capable of tolerating all particle strikes to any of their nodes. Moreover, they can mask Single Event Transients (SETs) occurring in combinational logics and reaching the input of the latches. We have compared our SEU/SET-tolerant latches with some well-known previously proposed soft error tolerant latches. To evaluate the proposed latches, we have done a set of SPICE simulations. The simulation results trough comparisons with other hardened latches reveal that the proposed latches not only have more robustness but... 

    On Temperature Dependency of Delay for Local,Intermediate, and Repeater Inserted Global Copper Interconnects

    , Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 23, Issue 12 , 2015 , Pages 3143-3147 ; 10638210 (ISSN) Alizadeh, A ; Sarvari, R ; Sharif University of Technology
    Abstract
    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... 

    Prediction of temperature variations and kinetics of austenite phase change on the run-out table

    , Article Materials Science and Engineering A ; Volume 421, Issue 1-2 , 2006 , Pages 260-267 ; 09215093 (ISSN) Serajzadeh, S ; Sharif University of Technology
    2006
    Abstract
    In this paper, a mathematical model has been developed to determine temperature distribution on the run-out table. The variational formulation and the finite element method have been employed to solve the governing conduction-convection equation. In order to avoid numerical instabilities due to the convection term, the heat transfer equation is first transformed to the standard form and then Raylieght-Ritz approximation technique and the finite element method have been utilized to solve the equation. To include the effect of phase transformation during cooling of steel, a second-order rate equation for describing austenite decomposition kinetics is coupled with the heat transfer model. A... 

    Single Event Multiple Upset (SEMU) tolerant latch designs in presence of process and temperature variations

    , Article Journal of Circuits, Systems and Computers ; Volume 24, Issue 1 , January , 2015 ; 02181266 (ISSN) Rajaei, R ; Tabandeh, M ; Fazeli, M ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    In this paper, we propose two novel soft error tolerant latch circuits namely HRPU and HRUT. The proposed latches are both capable of fully tolerating single event upsets (SEUs). Also, they have the ability of enduring single event multiple upsets (SEMUs). Our simulation results show that, both of our HRPU and HRUT latches have higher robustness against SEMUs as compared with other recently proposed radiation hardened latches. We have also explored the effects of process and temperature variations on different design parameters such as delay and power consumption of our proposed latches and other leading SEU tolerant latches. Our simulation results also show that, compared with the reference... 

    Effects of Obstacle Temperature and Motion on Particles Dispersion and Deposition in Cleanrooms

    , M.Sc. Thesis Sharif University of Technology Savalanpour Ardebili, Hamidreza (Author) ; Farhanieh, Bijan (Supervisor) ; Afshin, Hosein (Supervisor)
    Abstract
    Nowadays, indoor air quality (IAQ) is a major concern, particularly in cleanrooms where IAQ is controlled to ensure the extreme standards of cleanliness. For this reason, the particles rising from obstacles and distribution inside the indoor environments and cleanrooms are of great importance. In this study, effects of temperature field, releasing height of particles, and obstacle motion on particles rising from the obstacles inside the three-dimensional cleanroom were investigated by Lagrangian and dynamic mesh methods. The results indicated that, the greater the temperature difference between the top surface of the obstacle and airflow, the more the percentage of the particles risen from... 

    Evaluating two Model-Free data Interpertation Method for Measurments that are Influenced by Noise and Environmental Variations

    , M.Sc. Thesis Sharif University of Technology Sedighi, Sasan (Author) ; Abedian, Ali (Supervisor)
    Abstract
    Interpreting data of infrastructures monitored to detect damage of a structural is one of the most challenging issues of structural health monitoring (SHM). Especially, when environmental factors such as temperature, wind and humidity affect the data and the situation become more complicated. In this study, two methods of analysis free model of moving principal components analysis (MPCA) and robust regression analysis (RRA) have recently been considered for monitoring infrastructures compared with a variety of methods of data interpretation and results are presented. In this study, the performance of different ways in different loading conditions and arrangement of sensors have been... 

    Performance of Unbonded Post-Tensioned Concrete Slab Subjected to Temperature Variations

    , M.Sc. Thesis Sharif University of Technology Erfani, Ali (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Abstract
    Tests have shown that concrete post-tensioned slab under heat condition suffer a significant reduction in stiffness and strength. Design and implementation of post-tensioned concrete slabs with large spans of industrial structures exposed to extreme variation in temperature can be possible with detailed research on its behavior under heating condition. In this study numerical modelling of PT concrete slabs with unbonded tendons under heating condition was created based on available test results in the literature. A parametric study has been carried out and the results are presented for concrete coefficient thermal expansion, thermal contact conductance between the concrete and the cables,... 

    Climate Change and Mortality: Evidence from Iran

    , M.Sc. Thesis Sharif University of Technology Arab, Pouya (Author) ; Vesal, Mohammad (Supervisor)
    Abstract
    Due to the prominence of the evaluation of the consequences of rising temperatures, this paper examines the effects of temperature variation on mortality across different demographic groups in Iran. I use a rich weekly data set from 2009 to 2017 across different demographic groups to understand the potential health impacts of climate change in a developing country. Using several fixed effect regressions, I discover that for an additional day with a mean temperature over 25°C, mortality rate increases by 2.56% relative to the effects of an extra day in 0-5 °C, in the weekly temperature exposure horizon. I test for the harvesting effect by comparing the estimates at weekly and monthly... 

    Hot extrusion process modeling using a coupled upper bound-finite element method

    , Article Journal of Manufacturing Processes ; Vol. 16, issue. 2 , 2014 , pp. 233-240 ; ISSN: 15266125 Hosseinabadi, H. G ; Serajzadeh, S ; Sharif University of Technology
    Abstract
    A thermo-mechanical model has been developed for modeling of hot extrusion processes. Accordingly, an admissible velocity field was first proposed by means of stream function method and then, extrusion pressure as well as temperature variations within the metal and the die were predicted employing a combined upper bound and Petrov-Galerkin finite element analysis. In order to evaluate the model predictions, hot extrusion of AA6061-10%SiCp was considered under both isothermal and non-isothermal conditions and the predicted force-displacement diagrams under various extrusion conditions were compared with the experimental ones and reasonable consistency was found between the two sets of results... 

    Details study of ambient wind effect on heat dissipation capacity of thermal-powerplant dry cooling-towers

    , Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM ; Volume 1A , August 3–7 , 2014 , pp. V01AT03A017 ; ISSN: 08888116 ; ISBN: 9780791846216 Darbandi, M ; Behrouzifar, A ; Mirhashemi, A ; Salemkar, H ; Schneider, G. E ; Sharif University of Technology
    Abstract
    Thermal powerplants report a reduction in their dry cooling tower performances due to surrounding wind drafts. Therefore, it is very important to consider the influence of wind velocity in cooling tower design; especially in geographical points with high wind conditions. In this regard, we use the computational fluid dynamics (CFD) tool and simulate a dry cooling tower in different wind velocities of 0, 5 and 10 m/s. To extend our calculations; we also consider the temperature variation of circulating water through the tower heat exchanger or deltas one-by-one. We show that some heat exchangers around the tower cannot reduce the circulating water temperature sufficiently. This causes an... 

    Numerical simulation of low-mach-number laminar mixing and reacting flows using a dual-purpose pressure-based algorithm

    , Article Numerical Heat Transfer, Part B: Fundamentals ; Volume 59, Issue 6 , Jun , 2011 , Pages 495-514 ; 10407790 (ISSN) Ebrahimi Kebria, H ; Darbandi, M ; Hosseinizadeh, S. F ; Sharif University of Technology
    2011
    Abstract
    Benefitting from an analogy between compressible and incompressible governing equations, a novel dual-purpose, pressure-based finite-volume algorithm is suitably extended to simulate laminar mixing and reacting flows in low-Mach-number regimes. In our test cases, the Mach number is as high as 0.00326. Definitely, such low-Mach-number flows cannot be readily solved by either regular density-based solvers or most of their extensions. To examine the accuracy and performance of the extended formulation and algorithm, we simulate two benchmark cases including the mixing natural-convection flow in a square cavity with strong temperature gradients and the premixed reacting flow through annuli with... 

    Mathematical modeling of a slurry bubble column reactor for hydrodesulfurization of diesel fuel: Single- and two-bubble configurations

    , Article Chemical Engineering Research and Design ; Volume 100 , August , 2015 , Pages 362-376 ; 02638762 (ISSN) Khadem Hamedani, B ; Yaghmaei, S ; Fattahi, M ; Mashayekhan, S ; Hosseini Ardali, S. M ; Sharif University of Technology
    Institution of Chemical Engineers  2015
    Abstract
    In this investigation, a mathematical model for HDS of diesel fuel in a slurry bubble column reactor was developed. The model is based on the axial dispersion of the heterogeneous gas flow regime, which includes two various bubble classes: large (20±70mm) and small (1±10mm). By assuming only large or large plus small bubbles in the column, single- and two-bubble class mode equations are developed. The developed models to solving the mass and enthalpy balances from which the sulfur conversion was obtained that undertaken. The chemical kinetics over NiMoS/γ-Al2O3 catalyst were undertaken for the reaction rate of the involved reactions. The reactor operating conditions... 

    Coupling behavior of the pH/temperature sensitive hydrogels for the inhomogeneous and homogeneous swelling

    , Article Smart Materials and Structures ; Volume 25, Issue 8 , 2016 ; 09641726 (ISSN) Mazaheri, H ; Baghani, M ; Naghdabadi, R ; Sohrabpour, S ; Sharif University of Technology
    Institute of Physics Publishing  2016
    Abstract
    In this work, a model is developed to continuously predict homogeneous and inhomogeneous swelling behavior of pH/temperature sensitive PNIPAM hydrogels. Employing the model, homogeneous swelling of the pH/temperature sensitive hydrogel is investigated for free and biaxial constrained swelling cases. Comparing the model results with the experimental data available in the literature, the validity of the model is confirmed. The model is then employed to investigate inhomogeneous swelling of a spherical shell on a hard core both analytically and numerically for pH or temperature variations. In this regard, numerical tools are developed via preparing a user defined subroutine in ABAQUS software....