Loading...
Search for: air
0.018 seconds
Total 753 records

    Adsorption of proteins at the solution/air interface influenced by added nonionic surfactants at very low concentrations for both components. 3. dilational surface rheology

    , Article Journal of Physical Chemistry B ; Volume 119, Issue 9 , January , 2015 , Pages 3768-3775 ; 15206106 (ISSN) Fainerman, V. B ; Aksenenko, E. V ; Lylyk, S. V ; Lotfi, M ; Miller, R ; Sharif University of Technology
    Abstract
    The influence of the addition of the nonionic surfactants C12DMPO, C14DMPO, C10OH, and C10EO5 at concentrations between 10-5 and 10-1 mmol/L to solutions of β-casein (BCS) and β-lactoglobulin (BLG) at a fixed concentration of 10-5 mmol/L on the dilational surface rheology is studied. A maximum in the viscoelasticity modulus |E| occurs at very low surfactant concentrations (10-4 to 10-3 mmol/L) for mixtures of BCS with C12DMPO and C14DMPO and for mixtures of BLG with C10EO5, while for mixture of BCS with C10EO5 the value of |E| only slightly increased. The |E| values... 

    Adjoint-based design optimization of s-shaped intake geometry

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 3 November 2017 through 9 November 2017 ; Volume 1 , 2017 ; 9780791858349 (ISBN) Askari, R ; Shoureshi, P ; Soltani, M. R ; Khajeh Fard, A ; ASME ; Sharif University of Technology
    Abstract
    The S-shaped air intakes are very common shapes due to their ease in the engine-body integration or Radar Cross Section, RCS, specifications especially for fighter aircrafts. The numerical shape optimization of an S-shaped air intake using adjoint method is conducted. The flow of a specified air intake that uses S-duct M2129 is simulated using three dimensional (3D) numerical solution of Reynolds-Averaged Navier-Stokes equation along with k-ω SST turbulence model. The main purpose of this optimization scheme is to maximize the total pressure recovery (TPR). Further, the scheme is developed in such a way that would be applicable in industry thru satisfying specified constraint requirements.... 

    Adaptive fin failures tolerant integrated guidance and control based on backstepping sliding mode

    , Article Transactions of the Institute of Measurement and Control ; Volume 42, Issue 10 , 2020 , Pages 1823-1833 Ashrafifar, A ; Fathi Jegarkandi, M. F ; Sharif University of Technology
    SAGE Publications Ltd  2020
    Abstract
    An integrated guidance and control (IGC) is designed in this study for a surface-to-air missile considering burned or broken fin as a fault. The IGC model in the pitch plane is developed with various uncertainties in the presence of fin failure. The considered fault may cause a change in the vehicle’s shape that leads to a change in aerodynamic coefficients and consequently in the model. To identify the new model, aerodynamic coefficients are estimated using an estimator and the result is sent to the controller. Then, an adaptive robust controller is designed using the combination of backstepping and sliding mode scheme to compensate fin failure and changes in the dynamic. The simulation... 

    Adaptive attitude and position control of an insect-like flapping wing air vehicle

    , Article Nonlinear Dynamics ; Volume 85, Issue 1 , 2016 , Pages 47-66 ; 0924090X (ISSN) Banazadeh, A ; Taymourtash, N ; Sharif University of Technology
    Springer Netherlands 
    Abstract
    This study describes an adaptive sliding mode technique for attitude and position control of a rigid body insect-like flapping wing model in the presence of uncertainties. For this purpose, a six-degrees-of-freedom nonlinear and time-varying dynamic model of a typical hummingbird is considered for simulation studies. Based on the quasi-steady assumptions, three major aerodynamic loads including delayed stall, rotational lift and added mass are presented and analyzed, respectively. Using the averaging theory, a time-varying system is then transformed into the time-invariant system to design the adaptive controller. The controller is designed so that the closed-loop system will follow any... 

    Acoustic resonance scattering from a multilayered cylindrical shell with imperfect bonding

    , Article Ultrasonics ; Volume 49, Issue 8 , 2009 , Pages 682-695 ; 0041624X (ISSN) Rajabi, M ; Hasheminejad, S. M ; Sharif University of Technology
    Abstract
    The method of wave function expansion is adopted to study the three dimensional scattering of a time-harmonic plane progressive sound field obliquely incident upon a multi-layered hollow cylinder with interlaminar bonding imperfection. For the generality of solution, each layer is assumed to be cylindrically orthotropic. An approximate laminate model in the context of the modal state equations with variable coefficients along with the classical T-matrix solution technique is set up for each layer to solve for the unknown modal scattering and transmission coefficients. A linear spring model is used to describe the interlaminar adhesive bonding whose effects are incorporated into the global... 

    A cooperative machine learning approach for pedestrian navigation in indoor IoT

    , Article Sensors (Switzerland) ; Volume 19, Issue 21 , 2019 ; 14248220 (ISSN) Abadi, M. J ; Luceri, L ; Hassan, M ; Chou, C. T ; Nicoli, M ; Sharif University of Technology
    MDPI AG  2019
    Abstract
    This paper presents a system based on pedestrian dead reckoning (PDR) for localization of networked mobile users, which relies only on sensors embedded in the devices and device- to-device connectivity. The user trajectory is reconstructed by measuring step by step the user displacements. Though step length can be estimated rather accurately, heading evaluation is extremely problematic in indoor environments. Magnetometer is typically used, however measurements are strongly perturbed. To improve the location accuracy, this paper proposes a novel cooperative system to estimate the direction of motion based on a machine learning approach for perturbation detection and filtering, combined with... 

    A comprehensive comparative investigation on solar heating and cooling technologies from a thermo-economic viewpoint—A dynamic simulation

    , Article Energy Science and Engineering ; December , 2020 Jafari Mosleh, H ; Behnam, P ; Abbasi Kamazani, M ; Mohammadi, O ; Kavian, S ; Ahmadi, P ; Rosen, M. A ; Sharif University of Technology
    John Wiley and Sons Ltd  2020
    Abstract
    The yearly thermo-economic performance is dynamically investigated for three solar heating and cooling systems: solar heating and absorption cooling (SHAC), solar heating and ejector cooling (SHEC), and heating and solar vapor compression cooling (HSVC). First, the effects of important design parameters on the thermo-economic performance of the systems to supply the heating and cooling loads of the building are evaluated. The systems are parametrically analyzed with the weather conditions of Tehran, Iran. The results show that the life cycle costs (LCC) of the SHAC and HSVC systems are alike and much lower than those of the SHEC system. The HSVC system exhibits the best performance from... 

    A comprehensive comparative investigation on solar heating and cooling technologies from a thermo-economic viewpoint—A dynamic simulation

    , Article Energy Science and Engineering ; Volume 9, Issue 5 , 2021 , Pages 724-742 ; 20500505 (ISSN) Jafari Mosleh, H ; Behnam, P ; Abbasi Kamazani, M ; Mohammadi, O ; Kavian, S ; Ahmadi, P ; Rosen, M. A ; Sharif University of Technology
    John Wiley and Sons Ltd  2021
    Abstract
    The yearly thermo-economic performance is dynamically investigated for three solar heating and cooling systems: solar heating and absorption cooling (SHAC), solar heating and ejector cooling (SHEC), and heating and solar vapor compression cooling (HSVC). First, the effects of important design parameters on the thermo-economic performance of the systems to supply the heating and cooling loads of the building are evaluated. The systems are parametrically analyzed with the weather conditions of Tehran, Iran. The results show that the life cycle costs (LCC) of the SHAC and HSVC systems are alike and much lower than those of the SHEC system. The HSVC system exhibits the best performance from... 

    A comparison of light-duty vehicles' high emitters fractions obtained from an emission remote sensing campaign and emission inspection program for policy recommendation

    , Article Environmental Pollution ; Volume 286 , 2021 ; 02697491 (ISSN) Hassani, A ; Safavi, S. R ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Urban transportation is one of the leading causes of air pollution in big cities. In-use emissions of vehicles are higher than the emission control certification levels. The current study uses a roadside remote sensing emission monitoring campaign to investigate (a) fraction of high emitters in the light-duty vehicle (LDV) fleet and their contributions to the total emissions, (b) emission inspection (I/M) programs' effectiveness, and (c) alternate fuel (natural gas) encouragement policy. LDVs consist of passenger or freight transport vehicles with four wheels equivalent to classes M1 and N1 of European union vehicle classifications. The motivation is to assess the current emission inspection... 

    A comparison between the minimum-order & full-order observers in robust control of the air handling units in the presence of uncertainty

    , Article Energy and Buildings ; Volume 91 , 15 March , 2015 , Pages 115-130 ; ISSN: 3787788 Setayesh, H ; Moradi, H ; Alasty, A ; Sharif University of Technology
    Abstract
    Control of the air-handling units (AHU) is required to maintain satisfactory comfort conditions with low energy consumption. In the case of failure in sensor fusion systems of AHUs, full-order observers can be used as the supportive tool to provide an acceptable estimation of state variables. In this paper, a multivariable nonlinear model of the AHU is considered in the presence of uncertainties. The indoor temperature and relative humidity are controlled via manipulation of valve positions of air and cold water flow rates. In proposed hybrid control system, full and minimum-order observers are designed for the estimation of indoor temperature and relative humidity. Also, a regulator for... 

    A comparative study on the performance of HFO-1234yf and HFC-134a as an alternative in automotive air conditioning systems

    , Article Applied Thermal Engineering ; Volume 110 , 2017 , Pages 1091-1100 ; 13594311 (ISSN) Daviran, S ; Kasaeian, A ; Golzari, S ; Mahian, O ; Nasirivatan, S ; Wongwises, S ; Sharif University of Technology
    Abstract
    In this study, an automotive air conditioning system is simulated by considering HFO-1234yf (2,3,3,3-tetrafluoropropene) as the drop-in replacement of HFC-134a. The simulated air conditioning system consists of a multi-louvered fin and flat-plate type evaporator, a wobble-plate type compressor, a mini-channel parallel-flow type condenser and a thermostatic expansion valve. The thermodynamic properties of the refrigerants are extracted from the REFPROP 8.0 software, and a computer program is simulated for the thermodynamic analysis. Two different conditions have been considered in this program for the cycle analysis: for the first state, the cooling capacity is taken as constant, and for the... 

    Accuracy analysis of an integrated inertial navigation system in slow maneuvers

    , Article Navigation, Journal of the Institute of Navigation ; 2017 ; 00281522 (ISSN) Nobahari, H ; Mohammadkarimi, H ; Sharif University of Technology
    Wiley-Blackwell  2017
    Abstract
    In-motion alignment of a strapdown inertial navigation system, during slow maneuvers, is studied. Terrestrial velocity is fed back to the navigation system to estimate and compensate for the navigation errors. Observability of the errors is analyzed since the integrated navigation system is not fully observable. Then, the accuracy bounds of the navigation system in different motion scenarios are obtained analytically. Also, in order to minimize the errors of the navigation system, special maneuvers are designed based on the analytical derivations. The analytical results, obtained using the linearized error model, are verified through nonlinear simulation of different maneuvering and... 

    Accounting for systematic influences on preference heterogeneity in air travel

    , Article Transportation Research Record ; Issue 2300 , 2012 , Pages 147-154 ; 03611981 (ISSN) Rezaei, A ; Puckett, S. M ; Sharif University of Technology
    2012
    Abstract
    Modeling passengers' itinerary choice behavior helps in understanding the increasingly competitive airline market and in predicting air travel demand. Recently, investigation of the variation in passengers' preferences with regard to factors influencing their choice through estimation of the mixed multinomial logit model has received attention. An extended form of the model identifies sources of heterogeneity and consequently makes the choice models less restrictive in considering both systematic and random preference variation across individuals. This research investigates the existence of significant interactions between passengers' preference heterogeneity around the mean of random...