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    Tolerance analysis of mechanical assemblies with asymmetric tolerances

    , Article 2007 World Congress, Detroit, MI, 16 April 2007 through 19 April 2007 ; 2007 ; 01487191 (ISSN) Movahhedy, M. R ; Khodaygan, S ; Sharif University of Technology
    SAE International  2007
    Abstract
    This paper presents modified relations for worst-case and root-sum-square (RSS) tolerance accumulation models for tolerance analysis of mechanical assemblies with asymmetric tolerances. The common models do not consider the sign of the sensitivity factors and thus are applicable to symmetric tolerances only. Using the new models, the accumulation of asymmetric tolerances results in asymmetric assembly tolerances. New relationships for estimation of percent contributions of individual tolerances are also introduced which yield percent contributions of upper and lower bounds of independent variables (manufacturing dimensions) on the upper and lower bounds of dependent variables (assembly... 

    Multiple-chi-square tests and their application on distinguishing attacks

    , Article 2011 8th International ISC Conference on Information Security and Cryptology, ISCISC 2011, 14 September 2011 through 15 September 2011, Mashhad ; 2011 , Pages 55-60 ; 9781467300773 (ISBN) Vardasbi, A ; Salmasizadeh, M ; Mohajeri, J ; Sharif University of Technology
    2011
    Abstract
    Chi-square tests are vastly used for distinguishing random distributions, but extra care must be taken when using them on several independent variables. We noticed, the chisquare statistics, in some previous works, was computed half of its real value. Thus, to avoid possible future confusions, we formulize multiple-chi-square tests. To show the application of multiple-chi-square tests, we introduce two new tests and apply them to Trivium as a special case. These tests are modifications of ANF monomial test and, when applied to Trivium with the same number of rounds, the data complexity of them is roughly 24 times smaller than that of previous ANF monomial test  

    Streamline-based history matching constrained to reservoir geostatistics using gradual deformation technique

    , Article Petroleum Science and Technology ; Volume 29, Issue 17 , 2011 , Pages 1765-1777 ; 10916466 (ISSN) Shojaei, H ; Pishvaie, M. R ; Kamali, M. R ; Badakhshan, A ; Sharif University of Technology
    Abstract
    A new and general procedure for history matching that uses streamline simulation and a gradual deformation technique has been proposed. Streamline trajectories define the major flow paths and help the algorithm to modify the reservoir model only in the regions that cause the mismatch between simulation results and field observations. The use of a gradual deformation technique enables the algorithm to remain constrained to reservoir geostatistics. It also reduces the number of independent variables in the optimization problem. In our algorithm, effective conductivities are defined along each streamline. The effective streamline conductivities are then adjusted using the values of measured and... 

    Statistical monitoring of nominal logistic profiles in phase II

    , Article Communications in Statistics - Theory and Methods ; Volume 44, Issue 13 , 2015 , Pages 2689-2704 ; 03610926 (ISSN) Noorossana, R ; Izadbakhsh, H ; Aminnayer, M ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Abstract
    Statistical analysis of profile monitoring, a relatively new sub-area of statistical process control due to its applications in different industries, have urged researchers and practitioners to contribute to the developments of new monitoring methods. A statistical profile is a relationship between a quality characteristic (a response) and one or more independent variables to characterize quality of a process or a product. In this article, statistical profiles based on nominal responses are studied, where logistic regression is used to model the responses. Three approaches including likelihood ratio test (LRT), multivariate exponentially weighted moving average (MEWMA), and support vector... 

    Investigation of 2-nitrophenol solar degradation in the simultaneous presence of K2S2O8 and H2O2: Using experimental design and artificial neural network

    , Article Journal of Cleaner Production ; Volume 176 , 2018 , Pages 1154-1162 ; 09596526 (ISSN) Bararpour, S. T ; Feylizadeh, M. R ; Delparish, A ; Qanbarzadeh, M ; Raeiszadeh, M ; Feilizadeh, M ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    In this study, the interaction effect of K2S2O8 (PDS) and H2O2 (as two powerful oxidants) was investigated on the solar degradation of 2-nitrophenol (2-NF) in the two systems, i.e. absence and presence of Ag/S/TiO2 photocatalyst. Experiments were designed based on the central composite design, and two methods of response surface methodology (RSM) and artificial neural network (ANN) were developed for modeling of the systems. Concentrations of PDS and H2O2 were considered as independent variables and 2-NF degradation efficiency was selected as the response. It was revealed that the predictive capacity of ANN model is more than RSM model according to their corresponding R2, R2 adj RMS, MAE,... 

    Phosphomolybdic acid/graphene oxide as novel green catalyst using for biodiesel production from waste cooking oil via electrolysis method: Optimization using with response surface methodology (RSM)

    , Article Fuel ; Volume 287 , 2021 ; 00162361 (ISSN) Helmi, M ; Tahvildari, K ; Hemmati, A ; Aberoomand azar, P ; Safekordi, A ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    In this study, biodiesel (FAME) was prepared using a novel heterogeneous catalyst of phosphomolybdic acid (H3PMo12O40, HPMo)/support graphene oxide (GO). The characterization of the catalyst was evaluated by SEM, EDX, Map analysis, TEM, FT-IR, and Raman analyses. The production of biodiesel from waste cooking oil (WCO) was carried out by the electrolysis method. The process of the trans-esterification reaction was optimized by applying the response surface methodology (RSM) based on the central composite design (CCD) approach. The effects of four independent variables of methanol to oil molar ratio (6–12 mol:mol), catalyst weight (0.5–1.5 wt%), time (8–24 h), and voltage (30–70 V) were... 

    Optimization of uhmwpe/graphene nanocomposite processing using ziegler-natta catalytic system viaresponse surface methodology

    , Article Polymer - Plastics Technology and Engineering ; Vol. 53, Issue. 9 , June , 2014 , pp. 969-974 ; ISSN: 03602559 Shafiee, M ; Ramazani, S. A. A ; Sharif University of Technology
    Abstract
    Optimization of operational conditions for the preparation of Ultrahigh-molecular-weight polyethylene (UHMWPE)/Graphene nanocomposites with Ziegler-Natta catalyst was carried out via response surface methodology (RSM). This study deals with the optimization of process variables to optimize the productivity and molecular weight. A three-factor, three-level Box-Behnken design with temperature (X1), monomer pressure (X2), and [Al]/[Ti] molar ratio (X3) as the independent variables were selected for the study. The dependent variables were productivity and molecular weights of the final nanocomposites. It was developed by using the three parameters at three levels including 50, 60, and 70°C for... 

    A new approach to solve multi-response statistical optimization problems using neural network, genetic algorithm, and goal attainment methods

    , Article International Journal of Advanced Manufacturing Technology ; Vol. 75, issue. 5-8 , November , 2014 , pp. 1149-1162 Pasandideh, S. H. R ; Niaki, S. T. A ; Atyabi, S. M ; Sharif University of Technology
    Abstract
    Adjusting control factors (independent variables) to achieve an optimal level of output (response variable) is usually required in many real-world manufacturing problems. Common optimization methods often begin with estimating the relationship between a response and independent variables. Among these techniques, response surface methodology (RSM), due to its simplicity, has recently attracted extensive attention. However, on the one hand, in some cases, the relationship between a response and independent variables is too complex to be estimated using polynomial regression models. On the other hand, solving the obtained optimization model is not easy by exact methods. This paper introduces a... 

    Application-aware deadlock-free oblivious routing based on extended turn-model

    , Article IEEE/ACM International Conference on Computer-Aided Design, Digest of Technical Papers, ICCAD, 7 November 2011 through 10 November 2011, San Jose, CA ; 2011 , Pages 213-218 ; 10923152 (ISSN) ; 9781457713989 (ISBN) Shafiee, A ; Zolghadr, M ; Arjomand, M ; Sarbazi-Azad, H ; Sharif University of Technology
    Abstract
    Programmable hardware is gaining popularity as it can keep pace with growing performance demand in tight power budget, design and test cost, and serious reliability concerns of future multiprocessor embedded systems. Compatible with this trend, Network-on-Chip, as a potential bottleneck of future multi-cores, should also support pro-grammability. Here, we address this issue in design and implementation of routing algorithm for two-dimensional mesh. To this end, we allocate paths based on input traffic pattern and in parallel with customizing routing restriction for deadlock freedom. To achieve this, we propose extended turn model (ETM), a novel parametric deadlock-free routing for 2D meshes... 

    Tolerance analysis of assemblies with asymmetric tolerances by unified uncertainty-accumulation model based on fuzzy logic

    , Article International Journal of Advanced Manufacturing Technology ; Volume 53, Issue 5-8 , 2011 , Pages 777-788 ; 02683768 (ISSN) Khodaygan, S ; Movahhedy, M. R ; Sharif University of Technology
    Abstract
    In mechanical assemblies, individual components are placed together to deliver a certain function. The performance, quality, and cost of the mechanical assembly are significantly affected by its tolerances. Toleranced dimensions inherently generate an uncertain environment in a mechanical assembly. This paper presents a proper method for tolerance analysis of mechanical assemblies with asymmetric tolerances based on an uncertainty model. This mathematical approach is based on fuzzy logic and tolerance accumulation models such as worst-case and root-sum-square methods. A fuzzy-based tolerance representation is developed to model uncertainty of tolerance components in the mechanical... 

    Modeling and optimization of friction materials based on genetic programming and experimental frictional data

    , Article Journal of Reinforced Plastics and Composites ; Volume 34, Issue 7 , 2015 , Pages 581-590 ; 07316844 (ISSN) Khazaei, A ; Shojaei, A ; Sharif University of Technology
    SAGE Publications Ltd  2015
    Abstract
    A genetic programming technique was employed to develop empirical models for predicting specific wear rate and coefficient of friction on brake friction materials. The models consist of independent variables representing the volume fraction of the ingredients. The average absolute relative error for specific wear rate and coefficient of friction were found to be 1.93% and 1.92%, respectively. The models were also verified by the experimental data used for further control of the formulation. Utilizing Tornado plots, the models were found to be able to properly demonstrate the role of the ingredients on overall tribological performance of the brake friction materials. Moreover, a non-dominated... 

    A comparative study on car ownership modeling by applying fuzzy linear regression and artificial neural network - case study of Iran

    , Article Summer Computer Simulation Conference, SCSC 2010 - Proceedings of the 2010 Summer Simulation Multiconference, SummerSim 2010, 12 July 2010 through 14 July 2010 ; Issue 1 BOOK , 2010 , Pages 25-31 ; 9781617387029 (ISBN) Azadeh, A ; Rafiee, K ; Zohrevand, A.M ; Neshat, N ; Society for Modeling and Simulation International (SCS) ; Sharif University of Technology
    Abstract
    This paper models car ownership in Iran based on the data in a period of years 1980 to 2007 by artificial neural network (ANN) and Fuzzy Linear Regression (FLR). The car ownership is mainly affected by purchasing power of the customers, social and demographic factors; the car ownership model has a multi variable form. To explain the effect of these factors, ANN and FLR models are applied. The major reason for applying fuzzy concept and ANN is to overcome the inter-correlation problem associated with the independent variables. In this study, average family size; total population; urban population; urbanization rate; gross national product per capita; gasoline price; total length of road are... 

    Applying path analysis method in defining effective factors in organisation agility

    , Article International Journal of Production Research ; Volume 48, Issue 6 , 2010 , Pages 1765-1786 ; 00207543 (ISSN) Toloie Eshlaghy, A ; Mashayekhi, A. N ; Rajabzadeh, A ; Razavian, M. M ; Sharif University of Technology
    Abstract
    Changes in business environment are leading firms to adopt a new production model called agile manufacturing. This term moves away from the traditional mass production paradigm and focuses on manufacturing highly customised products when customers require them. In this paper, we present an initial approach to agile organisation based on case studies in an Iranian industrial organisation. An agile organisation conceptual model has been drawn up, based on the conclusions of the case study. The study presented here is of an exploratory factor analysis and the conclusions are drawn through path analysis, propose possible routes for future research in the field of agile organisation. By the... 

    Phosphomolybdic acid/graphene oxide as novel green catalyst using for biodiesel production from waste cooking oil via electrolysis method: optimization using with response surface methodology (RSM)

    , Article Fuel ; Volume 287 , March , 2021 Helmi, M ; Tahvildari, K ; Hemmati, A ; Aberoomand azar, P ; Safekordi, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    In this study, biodiesel (FAME) was prepared using a novel heterogeneous catalyst of phosphomolybdic acid (H3PMo12O40, HPMo)/support graphene oxide (GO). The characterization of the catalyst was evaluated by SEM, EDX, Map analysis, TEM, FT-IR, and Raman analyses. The production of biodiesel from waste cooking oil (WCO) was carried out by the electrolysis method. The process of the trans-esterification reaction was optimized by applying the response surface methodology (RSM) based on the central composite design (CCD) approach. The effects of four independent variables of methanol to oil molar ratio (6–12 mol:mol), catalyst weight (0.5–1.5 wt%), time (8–24 h), and voltage (30–70 V) were... 

    Linear and non-linear dynamic methods toward investigating proprioception impairment in non-specific low back pain patients

    , Article Frontiers in Bioengineering and Biotechnology ; Volume 8 , 2020 Shokouhyan, S. M ; Davoudi, M ; Hoviattalab, M ; Abedi, M ; Bervis, S ; Parnianpour, M ; Brumagne, S ; Khalaf, K ; Sharif University of Technology
    Frontiers Media S.A  2020
    Abstract
    Central nervous system (CNS) uses vision, vestibular, and somatosensory information to maintain body stability. Research has shown that there is more lumbar proprioception error among low back pain (LBP) individuals as compared to healthy people. In this study, two groups of 20 healthy people and 20 non-specific low back pain (NSLBP) participants took part in this investigation. This investigation focused on somatosensory sensors and in order to alter proprioception, a vibrator (frequency of 70 Hz, amplitude of 0.5 mm) was placed on the soleus muscle area of each leg and two vibrators were placed bilaterally across the lower back muscles. Individuals, whose vision was occluded, were placed... 

    Synthesis and optimization of CuxNi0.6-xMn0.4Fe2O4 oxygen carrier for chemical looping steam methane reforming

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; 2021 ; 15567036 (ISSN) Nazari, M ; Heydari Nasab, A ; Soltanieh, M ; Maddah, B ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Abstract
    The self-supported CuxNi0.6-xMn0.4Fe2O4 oxygen carrier (x = 0.1–0.5) is synthesized to be applied in the chemical looping steam methane reforming (CL-SMR) process through the synthesized co-precipitation method. The response surface methodology (RSM) based on the Box–Behnken model is adopted to evaluate the effects of independent variables on the functionality of responses as well as predicting the best response volume. In this method, the variables consisting of reaction temperature (550–700°C), oxygen carrier (OC) loading percentage (0.1–0.5), steam-to-CH4 ratio (S/C), (1.5–3.5), and redox cycles’ count (10–24) and the responses consisting of hydrogen (H2) production yield, CH4 conversion... 

    Numerical analysis of two-phase flow in heterogeneous porous media during pre-flush stage of matrix acidizing: Optimization by response surface methodology

    , Article Physics of Fluids ; Volume 33, Issue 5 , 2021 ; 10706631 (ISSN) Sabooniha, E ; Rokhforouz, M. R ; Kazemi, A ; Ayatollahi, S ; Sharif University of Technology
    American Institute of Physics Inc  2021
    Abstract
    Oil trapping behavior during the pre-flush stage is critically important to evaluate the effectiveness of matrix acidizing for the oil well stimulation. In this study, the visco-capillary behavior of the two-phase flow in the pore-scale is analyzed to investigate the influence of wetting properties for a natural rock sample. A two-dimensional model, based on Cahn-Hilliard phase-field and Navier-Stokes equations, was established and solved using the finite element method. A stability phase diagram for log capillary number (Ca)-log viscosity ratio (M) was constructed and then compared with the reported experimental works. The maximum and minimum ranges of capillary number and viscosity ratio... 

    Effects of electrophoretic deposition parameters on the photocatalytic activity of TiO2 films: Optimization by response surface methodology

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 452, Issue. 1 , 2014 , pp. 1-8 ; ISSN: 09277757 Mohammadi, M. M ; Vossoughi, M ; Feilizadeh, M ; Rashtchian, D ; Moradi, S ; Alemzadeh, I ; Sharif University of Technology
    Abstract
    In this work, the electrophoretic deposition method was utilized to immobilize TiO2 particles on stainless steel substrates. In addition, for the first time, statistics-based experimental design using response surface methodology was employed to investigate the effect of four key coating parameters (i.e. applied voltage, calcination temperature, photocatalyst weight percentage, and deposition time) on the photocatalytic degradation. Analysis of variance revealed that the proposed model was adequate. X-ray diffraction and scanning electron microscope were used to evaluate the effects of the parameters on degradation efficiency. The optimum applied voltage, calcination temperature, catalyst... 

    Combined UV-C/H2O2-VUV processes for the treatment of an actual slaughterhouse wastewater

    , Article Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes ; Volume 52, Issue 5 , 2017 , Pages 314-325 ; 03601234 (ISSN) Vaezzadeh Naderi, K ; Bustillo Lecompte, C. F ; Mehrvar, M ; Abdekhodaie, M. J ; Sharif University of Technology
    Taylor and Francis Inc  2017
    Abstract
    In this study, a three-factor, three-level Box-Behnken design with response surface methodology were used to maximize the TOC removal and minimize the H2O2 residual in the effluent of the combined UV-C/H2O2-VUV system for the treatment of an actual slaughterhouse wastewater (SWW) collected from one of the meat processing plants in Ontario, Canada. The irradiation time and the initial concentrations of total organic carbon (TOCo) and hydrogen peroxide (H2O2o) were the three predictors, as independent variables, studied in the design of experiments. The multiple response approach was used to obtain desirability response surfaces at the optimum factor settings. Subsequently, the optimum... 

    Goal equivalent manifold analysis of task performance in non-specific LBP and healthy subjects during repetitive trunk movement; effect of load, velocity, symmetry

    , Article Human Movement Science ; Volume 51 , 2017 , Pages 72-81 ; 01679457 (ISSN) Chehrehrazi, M ; Sanjari, M. A ; Mokhtarinia, H. R ; Jamshidi, A. A ; Maroufi, N ; Parnianpour, M ; Sharif University of Technology
    Abstract
    Motor abundance allows reliability of motor performance despite its variability. The nature of this variability provides important information on the flexibility of control strategies. This feature of control may be affected by low back pain (LPB) and trunk flexion/extension conditions. Goal equivalent manifold (GEM) analysis was used to quantify the ability to exploit motor abundance during repeated trunk flexion/extension in healthy individuals and people with chronic non-specific LBP (CNSLBP). Kinematic data were collected from 22 healthy volunteers and 22 CNSLBP patients during metronomically timed, repeated trunk flexion/extension in three conditions of symmetry, velocity, and loading;...