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Total 97 records

    Breaking Lander-Waterman's coverage bound

    , Article PLOS ONE ; Volume 11, Issue 11 , 2016 ; 19326203 (ISSN) Nashta Ali, D ; Motahari, S. A ; Hosseinkhalaj, B ; Sharif University of Technology
    Public Library of Science 
    Abstract
    Lander-Waterman's coverage bound establishes the total number of reads required to cover the whole genome of size G bases. In fact, their bound is a direct consequence of the well-known solution to the coupon collector's problem which proves that for such genome, the total number of bases to be sequenced should be O(G ln G). Although the result leads to a tight bound, it is based on a tacit assumption that the set of reads are first collected through a sequencing process and then are processed through a computation process, i.e., there are two different machines: one for sequencing and one for processing. In this paper, we present a significant improvement compared to Lander-Waterman's... 

    Generative model selection using a scalable and size-independent complex network classifier

    , Article Chaos ; Volume 23, Issue 4 , 2013 ; 10541500 (ISSN) Motallebi, S ; Aliakbary, S ; Habibi, J ; Sharif University of Technology
    2013
    Abstract
    Real networks exhibit nontrivial topological features, such as heavy-tailed degree distribution, high clusteringsmall-worldness. Researchers have developed several generative models for synthesizing artificial networks that are structurally similar to real networks. An important research problem is to identify the generative model that best fits to a target network. In this paper, we investigate this problem and our goal is to select the model that is able to generate graphs similar to a given network instance. By the means of generating synthetic networks with seven outstanding generative models, we have utilized machine learning methods to develop a decision tree for model selection. Our... 

    Analytical solution for the free vibration analysis of delaminated timoshenko beams

    , Article The Scientific World Journal ; Volume 2014 , 2014 ; ISSN: 1537744X Jafari Talookolaei, R. A ; Abedi, M ; Sharif University of Technology
    Abstract
    This work presents a method to find the exact solutions for the free vibration analysis of a delaminated beam based on the Timoshenko type with different boundary conditions. The solutions are obtained by the method of Lagrange multipliers in which the free vibration problem is posed as a constrained variational problem. The Legendre orthogonal polynomials are used as the beam eigenfunctions. Natural frequencies and mode shapes of various Timoshenko beams are presented to demonstrate the efficiency of the methodology  

    Methods to Derive the Differential Equation of the Free Surface Boundary

    , Article Ground Water ; Volume 49, Issue 2 , 2011 , Pages 133-143 ; 0017467X (ISSN) Wang, X. S ; Neuman, S. P ; Strack, O. D. L ; Verruijt, A ; Jamali, M ; Seymour, B ; Bear, J ; Cheng, A. H. D ; Chen, C ; Kuang, X ; Jiao, J. J ; Sharif University of Technology
    2011

    Theoretical modeling and simulation of higher order FWM crosstalks in multichannel WDM optical communication systems

    , Article Advanced Materials Research, Xiamen ; Volume 660 , 2013 , Pages 130-134 ; 10226680 (ISSN) ; 9783037856413 (ISBN) Yazdani, A ; Noshad, M ; Farrokhi, A ; Sharif University of Technology
    2013
    Abstract
    In this paper, we derive a theoretical model for the higher order FWM power in WDM networks with NZDSF fibers for the first time. We have investigated the higher order FWM power theoretically and by numerical simulations. Dividing the fiber into finite number of elements and applying the boundary conditions, allow us derive an expression for second order power penalty. At the end of each element we derive the first order FWM power for all wavelengths and use these values to calculate the second order FWM power in the next element. Consequently, for each channel we can compute the total second order FWM power penalty at the end of the fiber  

    A modified solar desalination system using evacuated tube collector

    , Article Desalination ; Volume 396 , 2016 , Pages 30-38 ; 00119164 (ISSN) Shafii, M. B ; Jahangiri Mamouri, S ; Lotfi, M. M ; Jafari Mosleh, H ; Sharif University of Technology
    Elsevier  2016
    Abstract
    Solar energy is turning to one of the important types of clean energies, due to its availability, and its potential for wide range of applications. In this work, a new passive solar desalination system is introduced, which benefits from excellences of twin-glass evacuated tube collectors. For the first time, the evacuated tube collector is not only used as the solar thermal collector, but also as a basin to heat the water. Hence, the thermal resistance between the collector and basin is virtually eliminated. Results show a considerable increase in the rate of desalinated water production and the maximum production reaches up to 0.83 kg/(m2·h). It was observed that the maximum rate of the... 

    Multi-item multiperiodic inventory control problem with variable demand and discounts: A particle swarm optimization algorithm

    , Article Scientific World Journal ; Vol. 2014 , 2014 ; ISSN: 23566140 Mousavi, S. M ; Niaki, S. T. A ; Bahreininejad, A ; Musa, S. N ; Sharif University of Technology
    Abstract
    A multi-item multiperiod inventory control model is developed for known-deterministic variable demands under limited available budget. Assuming the order quantity is more than the shortage quantity in each period, the shortage in combination of backorder and lost sale is considered. The orders are placed in batch sizes and the decision variables are assumed integer. Moreover, all unit discounts for a number of products and incremental quantity discount for some other items are considered. While the objectives are to minimize both the total inventory cost and the required storage space, the model is formulated into a fuzzy multicriteria decision making (FMCDM) framework and is shown to be a... 

    Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering

    , Article Review of Scientific Instruments ; Volume 85, Issue 5 , May , 2014 ; ISSN: 00346748 Ott, D ; Reihani, S. N. S ; Oddershede, L. B ; Sharif University of Technology
    Abstract
    In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required... 

    Extension of weighted sum of gray gas data to mathematical simulation of radiative heat transfer in a boiler with gas-soot media

    , Article The Scientific World Journal ; Vol. 2014 , 2014 ; ISSN: 1537744X Gharehkhani, S ; Nouri-Borujerdi, A ; Kazi, S. N ; Yarmand, H ; Sharif University of Technology
    Abstract
    In this study an expression for soot absorption coefficient is introduced to extend the weighted-sum-of-gray gases data to the furnace medium containing gas-soot mixture in a utility boiler 150 MWe. Heat transfer and temperature distribution of walls and within the furnace space are predicted by zone method technique. Analyses have been done considering both cases of presence and absence of soot particles at 100% load. To validate the proposed soot absorption coefficient, the expression is coupled with the Taylor and Foster's data as well as Truelove's data for CO2-H2O mixture and the total emissivities are calculated and compared with the Truelove's parameters for 3-term and 4-term gray... 

    Dynamics of nanodroplets on wettability gradient surfaces

    , Article Journal of Physics Condensed Matter ; Volume 23, Issue 8 , February , 2011 ; 09538984 (ISSN) Moosavi, A ; Mohammadi, A ; Sharif University of Technology
    2011
    Abstract
    A lubrication model is used to study the dynamics of nanoscale droplets on wettability gradient surfaces. The effects of the gradient size, size of the nanodroplets and the slip on the dynamics have been studied. Our results indicate that the position of the center of mass of the droplets can be well described in terms of a third-order polynomial function of the time of the motion for all the cases considered. By increasing the size of the droplets the dynamics increases. It is also shown that the slip can considerably enhance the dynamics. The results have been compared with the results obtained using theoretical models and molecular dynamics simulations  

    Analytical relations for long-droplet breakup in asymmetric T junctions

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 91, Issue 5 , May , 2015 ; 15393755 (ISSN) Bedram, A ; Moosavi, A ; Hannani, S. K ; Sharif University of Technology
    American Physical Society  2015
    Abstract
    We develop accurate analytical relations for the droplet volume ratio, droplet length during breakup process, and pressure drop of asymmetric T junctions with a valve in each of the branches for producing unequal-sized droplets. An important advantage of this system is that after manufacturing the system, the size of the generated droplets can be changed simply by adjusting the valves. The results indicate that if the valve ratio is smaller than 0.65, the system enters a nonbreakup regime. Also the pressure drop does not depend on the time and decreases by increasing the valve ratio, namely, opening the degree of valve 1 to valve 2. In addition, the results reveal that by decreasing... 

    Unbinding of kinesin from microtubule in the strongly bound states enhances under assisting forces

    , Article Molecular Informatics ; Volume 37, Issue 4 , April , 2018 ; 18681743 (ISSN) Khataee, H ; Naseri, S ; Zhong, Y ; Liew, A. W. C ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Abstract
    The ability to predict the cellular dynamics of intracellular transport has enormous potential to impact human health. A key transporter is kinesin-1, an ATP-driven molecular motor that shuttles cellular cargos along microtubules (MTs). The dynamics of kinesins depends critically on their unbinding rate from MT, which varies depending on the force direction applied on the motor, i.e. the force-unbinding rate relation is asymmetric. However, it remains unclear how changing the force direction from resisting (applied against the motion direction) to assisting (applied in the motion direction) alters the kinesin's unbinding and stepping. Here, we propose a theoretical model for the influence of... 

    Penetration of elliptical liquid jets in low-speed crossflow

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 141, Issue 1 , 2019 ; 00982202 (ISSN) Morad, M. R ; Khosrobeygi, H ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2019
    Abstract
    Trajectory and penetration of elliptical liquid jets emerged into a low-speed crossflow of air are studied. The jets are introduced to the crossflow at different momentum ratios ranging from 1 to 300. The images are analyzed to obtain the trajectories of the outer boundary of the jets for two different aspect ratios. An empirical correlation is proposed for the present injector geometries and for the range of momentum ratio, Weber, and Reynolds numbers used in this study. Finally, a theoretical model for the trajectory of the liquid column for an initially elliptical liquid emerging into a crossflow is presented, and the associated drag coefficients are obtained for a precise trajectory... 

    Penetration of elliptical liquid jets in low-speed crossflow

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 141, Issue 1 , 2019 ; 00982202 (ISSN) Morad, M. R ; Khosrobeygi, H ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2019
    Abstract
    Trajectory and penetration of elliptical liquid jets emerged into a low-speed crossflow of air are studied. The jets are introduced to the crossflow at different momentum ratios ranging from 1 to 300. The images are analyzed to obtain the trajectories of the outer boundary of the jets for two different aspect ratios. An empirical correlation is proposed for the present injector geometries and for the range of momentum ratio, Weber, and Reynolds numbers used in this study. Finally, a theoretical model for the trajectory of the liquid column for an initially elliptical liquid emerging into a crossflow is presented, and the associated drag coefficients are obtained for a precise trajectory... 

    Beam profile and image transfer study in multimode optical fiber coupling

    , Article Journal of Applied Sciences ; Volume 8, Issue 22 , 2008 , Pages 4210-4214 ; 18125654 (ISSN) Asadpour, A ; Golnabi, H ; Sharif University of Technology
    2008
    Abstract
    In this study the optical beam transfer and imaging in an optical fiber coupling is discussed. In coupling two fibers, some measurements from intensity perspective are performed and intensity profile is investigated. A theoretical model for the power transmission in fiber coupling is developed and theoretical function is compared with the experimental results. The amount of light delivered to the receiving fiber depends on the acceptance angle of the receiving fiber and the core cross sections of both fibers. Intensity profile function obtained theoretically agrees well with the measured results. The intensity variation as a function of the air gap variation is investigated in this article.... 

    Behavior of polymer concrete beam/pile confined with CFRP sleeves

    , Article Mechanics of Advanced Materials and Structures ; 2017 , Pages 1-8 ; 15376494 (ISSN) Toufigh, V ; Toufigh, V ; Saadatmanesh, H ; Ahmari, S ; Kabiri, E ; Sharif University of Technology
    Abstract
    This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity. © 2017 Taylor... 

    Behavior of polymer concrete beam/pile confined with CFRP sleeves

    , Article Mechanics of Advanced Materials and Structures ; Volume 26, Issue 4 , 2019 , Pages 333-340 ; 15376494 (ISSN) Toufigh, V ; Toufigh, V ; Saadatmanesh, H ; Ahmari, S ; Kabiri, E ; Sharif University of Technology
    Taylor and Francis Inc  2019
    Abstract
    This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity  

    Modeling for Sensing Behavior of SnO2-CuO Nanostructures toward H2S Gas

    , Ph.D. Dissertation Sharif University of Technology Boroun, Zhoubin (Author) ; Ghorbani, Mohammad (Supervisor) ; Moosavi, Ali (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
    Abstract
    H2S is a toxic and corrosive gas which is detrimental for both human’s health and some of important industries such as oil and gas. Based on different experimental research among various systems, resistive sensors fabricated from SnO2-CuO nanostructures have promising performance toward detection of this gas. High sensitivity and selectivity, response time of order of seconds, recovery times of order of tens of seconds and determining concentration of H2S gas below ppm level are advantages of this system. Unfortunately due to lack of a theoretical model, current experimental researches are excessively based on “trial and error” methodology. In this research some of the basic questions which... 

    Experimental design in analytical chemistry -Part I: Theory

    , Article Journal of AOAC International ; Vol. 97, issue. 1 , 2014 , pp. 3-11 ; ISSN: 10603271 Ebrahimi-Najafabadi, H ; Leardi, R ; Jalali-Heravi, M ; Sharif University of Technology
    Abstract
    This paper reviews the main concepts of experimental design applicable to the optimization of analytical chemistry techniques. The critical steps and tools for screening, including Plackett-Burman, factorial and fractional factorial designs, and response surface methodology such as central composite, Box-Behnken, and Doehlert designs, are discussed. Some useful routines are also presented for performing the procedures  

    Study on the catalytic activity and theoretical modeling of a novel dual acidic mesoporous silica

    , Article RSC Advances ; Volume 4, Issue 32, 2014 , 2014 , Pages 16647-16654 ; ISSN: 20462069 Vafaeezadeh, M ; Fattahi, A ; Sharif University of Technology
    Abstract
    A novel mesoporous silica-functionalized dual Brønsted acidic species has been introduced as an efficient catalyst for solvent-free esterification of fatty acids with ethanol. The structure of the catalyst has been characterized by FT-IR spectroscopy, thermal gravimetric analysis (TGA), TEM and N2 adsorption-desorption. TGA of catalyst 1 showed no weight loss before 200 °C, indicating a high degree of hydrophobicity of the surface of the mesoporous silica. TEM images and nitrogen adsorption-desorption showed no noticeable changes to the structure of the catalyst before and after acid treatment. pH metric analysis was performed for the catalyst to determine the loading of the acidic sites....