Loading...
Search for:
aggregation
0.007 seconds
Total 257 records
Aggregation and detection of magnetic nanoparticles in microfluidic channels
, Article Journal of Electrical Engineering ; Volume 63, Issue 7 SUPPL , 2012 , Pages 27-30 ; 13353632 (ISSN) ; Kokabi, H ; Gamby, J ; Ngo, K. A ; Krause, H. J ; Fardmanesh, M ; Sharif University of Technology
2012
Abstract
Incorporating numerical simulation with COMSOL Multiphysics, the aggregation and detection of superparamagnetic nanoparticles in microfluidic channels are investigated. Considering the physical specifications of the implemented microchannels, the parameters which determine the ability of the system for aggregation and detection of the particles are examined and simulated. Based on the simulation results, we propose a new approach for both capturing and detecting of the magnetic nanoparticles passing through microchannels
Revisiting optimal rank aggregation: A dynamic programming approach
, Article ICTIR 2015 - Proceedings of the 2015 ACM SIGIR International Conference on the Theory of Information Retrieval, 27 September 2015 through 30 September 2015 ; 2015 , Pages 353-356 ; 9781450338332 (ISBN) ; Dadashkarimi, J ; Dehghani, M ; Esfahani, H. N ; Shakery, A ; Sharif University of Technology
Association for Computing Machinery, Inc
2015
Abstract
Rank aggregation, that is merging multiple ranked lists, is a pivotal challenge in many information retrieval (IR) systems, especially in distributed IR and multilingual IR. From the evaluation point of view, being able to calculate the upper-bound of performance of the final aggregated list lays the ground for evaluating different aggregation strategies, independently. In this paper, we propose an algorithm based on dynamic programming which, using relevancy information, obtains the aggregated list with the maximum performance that could be possibly achieved by any aggregation strategy. We also provide a detailed proof for the optimality of the result of the algorithm. Furthermore, we...
A Visual Colorimetric Probe for Naked-Eye Detection of Pamidronate Disodium in Human Plasma Based on Aggregation of Citrate-Capped Gold Nanoparticles
, Article Plasmonics ; Volume 10, Issue 4 , 2015 , Pages 971-978 ; 15571955 (ISSN) ; Abbasi-Moayed, S ; Sharif University of Technology
Springer New York LLC
2015
Abstract
Herein, a sensitive, simple, and rapid colorimetric assay for the detection of pamidronate disodium was developed based on the aggregation of citrate-capped gold nanoparticles (AuNPs). This was exploited from the affinity of electron-rich atoms toward the surface of AuNPs, resulting in the aggregation of AuNPs through intermolecular hydrogen bonding interactions. As a result of aggregation under optimum conditions ([NaCl] = 25 mM, [AuNPs] = 3.3 nM and pH 7.0), the color of AuNPs was changed from red to blue and the plasmon band of AuNPs around 520 was decreased along with the formation of a new peak at a longer wavelength in the approximate range of 600 to 700 nm. The intensity ratios of...
Microstructure-based visco-elastoplastic continuum model of asphalt concrete
, Article RILEM Bookseries ; Volume 11 , 2016 , Pages 37-48 ; 22110844 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
Kluwer Academic Publishers
2016
Abstract
Asphalt concrete is a heterogeneous and multi-phase material that consists of aggregates, asphalt binder, and pores. These components create a complex microstructure. There is no consensus on how to quantify the microstructure and the required parameters from two-dimensional images. The load transfer can be managed by aggregate-aggregate or aggregate-mastic interactions that depend on the gradation, aggregate internal structure, and asphalt binder viscoelastic properties. The most important internal structure indices affecting the behavior of HMA are aggregate orientation, contact orientation, contact length, and number of contact points. In this paper, the influence of aggregate structure...
Effects of drying temperature and aggregate shape on the concrete compressive strength: Experiments and data mining techniques
, Article International Journal of Engineering Transactions C: Aspects ; Volume 33, Issue 9 , 2020 , Pages 1780-1791 ; Ghorbani, S ; Forouzanmehr, M ; Sharif University of Technology
Materials and Energy Research Center
2020
Abstract
The main purpose of this paper is to assess the impact of the geometry and size of the aggregate, as well as the drying temperature on the compressive strength of the ordinary concrete. To this end, two aggregates with sharp and round corners were prepared in three different aggregate sizes. After preparing concrete samples, the drying operations were carried out in the vicinity of room temperature, cold wind, and hot wind. Next, the linear relationship between the concrete strength and the studied parameters was estimated using Multiple Linear Regression (MLR) method. Finally, the Taguchi Sensitivity Analysis (TSA) and Decision Tree Analysis (DTA) were applied in order to determine the...
A comprehensive investigation into the effect of aging and coarse aggregate size and volume on mechanical properties of self-compacting concrete
, Article Materials and Design ; Vol. 59, issue , 2014 , pp. 199-210 ; ISSN: 10263098 ; Beygi, M. H. A ; Kazemi, M. T ; Vaseghi Amiri, J ; Rahmani, E ; Rabbanifar, S ; Eslami, M ; Sharif University of Technology
Abstract
The popularity of self-compacting concrete (SCC), as an innovative construction materials in concrete industry, has increased all over the world in recent decades. SCC offers a safer construction process and durable concrete structure due to its typical fresh concrete behavior which is achieved by SCC's significantly different mixture composition. This modification of mix composition may have significant effect on the hardened mechanical properties of SCC as compared to normal vibrated concrete (NVC). Therefore, it is necessary to know whether the use of all rules and relations that have been formulated for NVC in current design codes based on years of experience are also valid for SCC....
Spectrophotometric and Colorimetric Determination of 4-Hydroxy-2 -Mercapto-6-Methylpyrimidine (MTU) Based on the Aggregation of Gold Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Hormozinezhad, Mohammad Reza (Supervisor)
Abstract
4-Hydroxy-2-mercapto-6-methylpyrimidine (MTU), is a drug from thiouracil antithyroid family which inhibits thyroid hormone synthesis and is generally used to remedy hyperthyroidism in gestation and liver disease. On the other hand, MTU has been applied to animals to gain higher weight . Since remaining of thyreostatic drugs in eatable animal tissues could be a risk to human health, their use in animal products was prohibited in the European Union in 1981.Based on these reasons, the need for an analytical procedure capable of determining MTU is of great importance. We report herein the development of a highly sensitive colorimetric method for the detection of MTU utilizing citrate capped gold...
Team selection for prediction tasks
, Article Journal of Combinatorial Optimization ; 2014 ; ISSN: 15732886 ; Ghazimatin, A ; Habibi, J ; Haghshenas, H ; Sharif University of Technology
Abstract
Given a random variable (Formula presented.) and a set of experts (Formula presented.), we describe a method for finding a subset of experts (Formula presented.) whose aggregated opinion best predicts the outcome of (Formula presented.). Therefore, the problem can be regarded as a team formation for performing a prediction task. We show that in case of aggregating experts' opinions by simple averaging, finding the best team (the team with the lowest total error during past (Formula presented.) rounds) can be modeled with an integer quadratic programming and we prove its NP-hardness whereas its relaxation is solvable in polynomial time. At the end, we do an experimental comparison between...
Evaluation of the effect of maximum aggregate size on fracture behavior of self compacting concrete
, Article Construction and Building Materials ; Vol. 55 , 2014 , pp. 202-211 ; ISSN: 09500618 ; Kazemi, M. T ; Vaseghi Amiri, J ; Nikbin, I. M ; Rabbanifar, S ; Rahmani, E ; Sharif University of Technology
Abstract
This paper presents and discusses the effect of maximum size of coarse aggregate on fracture characteristics and brittleness of self-compacting concrete (SCC). Based on an experimental program, a series of three point bending tests were carried out on 86 notched beams, as recommended by RILEM. For all mixes, the parameters were analyzed by the work-of-fracture method (WFM) and by the size effect method (SEM) and consequently a correlation between these methods was obtained which is used to calibrate cracking numerical models. Test results showed that with increase of size of coarse aggregate, (a): fracture energies of GF in WFM and Gf in SEM increase which may be explained by the change in...
A colorimetric assay for d-Penicillamine in urine and plasma samples based on the aggregation of gold nanoparticles
, Article Journal of the Iranian Chemical Society ; Vol. 11, issue. 5 , Dec , 2014 , p. 1249-1255 ; Azargun, M ; Fahimi-Kashani, N ; Sharif University of Technology
Abstract
We report herein the development of a highly sensitive colorimetric method for detection of d-Penicillamine using citrate-capped gold nanoparticles (AuNPs). This assay relies upon the distance-dependent of gold nanoparticles surface plasmon resonance band of gold nanoparticles. By replacing the thiol-containing chelator drug, d-Penicillamine, with citrate on the gold nanoparticles surface, a new peak appearing at a longer wavelength intensifies and shifts further to the red from the original peak position due to aggregation of gold nanoparticles which depends on ionic strength, gold nanoparticles and d-Penicillamine concentration. During this process, the plasmon band at 521 nm decreases...
Modified MODFLOW-based model for simulating the agglomeration and transport of polymer-modified Fe0 nanoparticles in saturated porous media
, Article Environmental Science and Pollution Research ; 2015 ; 09441344 (ISSN) ; Fagerlund, F ; Shamsai, A ; Lowry, G. V ; Phenrat, T ; Sharif University of Technology
Springer Verlag
2015
Abstract
The solute transport model MODFLOW has become a standard tool in risk assessment and remediation design. However, particle transport models that take into account both particle agglomeration and deposition phenomena are far less developed. The main objective of the present study was to evaluate the feasibility of adapting the standard code MODFLOW/MT3D to simulate the agglomeration and transport of three different types of polymer-modified nanoscale zerovalent iron (NZVI) in one-dimensional (1-D) and two-dimensional (2-D) saturated porous media. A first-order decay of the particle population was used to account for the agglomeration of particles. An iterative technique was used to optimize...
On the effect of temperature on precipitation and aggregation of asphaltenes in light live oils
, Article Canadian Journal of Chemical Engineering ; Volume 94, Issue 9 , 2016 , Pages 1820-1829 ; 00084034 (ISSN) ; Rashidi, F ; Mousavi Dehghani, S. A ; Ghazanfari, M. H ; Sharif University of Technology
Wiley-Liss Inc
Abstract
Asphaltene precipitation and deposition is a serious issue in all facets of petroleum production and processing. Despite the numerous experimental efforts concerning asphaltenes, the effect of temperature on asphaltene precipitation and aggregation in live oils remains an elusive and controversial subject in the available literature. In this work, a series of high pressure-high temperature depressurization experiments were designed to assess the effect of temperature on asphaltene precipitation and aggregation in light live oils. Asphaltene related experiments were performed using a high pressure microscope and high pressure-high temperature filtration setup on a light live oil with a low...
Anti-aggregation of gold nanoparticles for metal ion discrimination: a promising strategy to design colorimetric sensor arrays
, Article Sensors and Actuators, B: Chemical ; Volume 270 , 2018 , Pages 545-551 ; 09254005 (ISSN) ; Ghasemi, F ; Hormozi Nezhad, M. R ; Sharif University of Technology
Abstract
The first report of anti-aggregation-based sensor arrays is presented. The strategy is based on the competitive interaction of citrate-capped gold nanoparticles (AuNPs) and heavy metal ions (i.e., Hg(II), Ag(I), Fe(III), and Pb(II)) with three aggregation reagents (i.e., cysteine, melamine, and arginine). In the presence of aggregation reagent, the color and UV–vis spectra of AuNPs are changed indicating the aggregation of AuNPs. Addition of the aggregation reagents which are firstly treated with the ions, causes AuNPs turn from the aggregation to the dispersion state. The anti-aggregation capability of ions towards various aggregation reagents is different because of distinct stability...
Thin film graphene oxide membrane: challenges and gas separation potential
, Article Korean Journal of Chemical Engineering ; Volume 35, Issue 5 , May , 2018 , Pages 1174-1184 ; 02561115 (ISSN) ; Karimi Sabet, J ; Ghotbi, C ; Abbasi, Z ; Sharif University of Technology
Springer New York LLC
2018
Abstract
Graphene oxide membranes were prepared by vacuum and pressurized ultrafiltration methods on the 12% modified Polyacrylonitrile (12mPAN) substrate to specify challenges, salient features, future directions, and potential of GO membrane for separation fields using characterization techniques and gas separation test (studied gases are CO2, He and N2), which is an efficient tool for better understanding of GO membrane behavior. GO membrane structure was examined over a wide range of parameters, such as pore size range of substrate and its surface properties, pH of GO dispersion, GO content, synthesis pressure, operating pressure and temperature. The results show that the GO content does not hold...
Modified MODFLOW-based model for simulating the agglomeration and transport of polymer-modified Fe0 nanoparticles in saturated porous media
, Article Environmental Science and Pollution Research ; Volume 25, Issue 8 , 2018 , Pages 7180-7199 ; 09441344 (ISSN) ; Fagerlund, F ; Shamsai, A ; Lowry, G. V ; Phenrat, T ; Sharif University of Technology
Springer Verlag
2018
Abstract
The solute transport model MODFLOW has become a standard tool in risk assessment and remediation design. However, particle transport models that take into account both particle agglomeration and deposition phenomena are far less developed. The main objective of the present study was to evaluate the feasibility of adapting the standard code MODFLOW/MT3D to simulate the agglomeration and transport of three different types of polymer-modified nanoscale zerovalent iron (NZVI) in one-dimensional (1-D) and two-dimensional (2-D) saturated porous media. A first-order decay of the particle population was used to account for the agglomeration of particles. An iterative technique was used to optimize...
Size influence of specimens and maximum aggregate on dam concrete: compressive strength
, Article Journal of Materials in Civil Engineering ; Volume 21, Issue 8 , 2009 , Pages 349-355 ; 08991561 (ISSN) ; Mohamadi Shooreh, M. R ; Askari, S. M ; Sharif University of Technology
2009
Abstract
The compressive strength of mass concrete in dams is obtained from laboratory experiments of various cylindrical specimens with diameters of 150, 250, and 300 mm, and heights of 300, 500, and 450 mm, respectively. These specimens with 37.5, 75, and 150 mm maximum size of aggregate were investigated. The 7- and 90-day compressive strength of concrete was found to be between 20 and 58 MPa depending on the size of the specimens. The results reveal the existence of a significant size effect. Based on test results, relationships between the strength of mass concrete specimens and their size and shape are developed. Finally, results and a discussion are presented regarding compressive strength...
Experimental research on the performance of lightweight concrete containing foam and expanded clay aggregate
, Article Composites Part B: Engineering ; Volume 171 , 2019 , Pages 46-60 ; 13598368 (ISSN) ; Chen, B ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
This work addresses the preparation of self-flowing lightweight aggregate foamed concrete (LAFC) resulting from the mixing of stable foam, expanded clay aggregate (ECA) and silica fume (SF) as main raw materials. Formulated LAFC mixtures were tested for the mechanical, thermal, sorption and high-temperature resistance properties. Results showed that the increase in the volume of foam from 0% to 20% considerably improved the flowability of LAFC and LAFC mixtures were categorized into high stable visual stability index. Compressive strength of LAFC mixtures was reduced from 24.75 MPa to 21.10, 15.95 and 12.05 MPa respectively when foam volume was increased from 0% to 10, 15 and 20%. Thermal...
Evaluation of Aggregate Angularity Using Image Analysis
, M.Sc. Thesis Sharif University of Technology ; Tabatabaee, Nader (Supervisor)
Abstract
Form and angularity of aggregates are two important shape characteristics that have a significant effect on the performance of hot-mix asphalt. The first step toward the study of the effect of these characteristics on pavement performance is their proper measurement. Current test methods used in practice have several limitations in measuring these characteristics. In this thesis, a method based on image processing called “Sharif Aggregate Imaging System (SHAMS)” has been introduced which is capable of directly measuring aggregate dimensions and determining angularity index for aggregates classification. Calculated results related to the form and angularity of aggregates measured by SHAMS...
Integrity checking for aggregate queries
, Article IEEE Access ; Volume 9 , 2021 , Pages 74068-74084 ; 21693536 (ISSN) ; Amini, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
With the advent of cloud computing and Internet of Things and delegation of data collection and aggregation to third parties, the results of the computations should be verified. In distributed models, there are multiple sources. Each source creates authenticators for the values and sends them to the aggregator. The aggregator combines the authenticated values and creates a verification object for verifying the computation/aggregation results. In this paper, we propose two constructions for verifying the results of countable and window-based countable functions. These constructions are useful for aggregate functions such as median, max/min, top-k/first-k, and range queries, where the...
Kinetics of asphaltene aggregation phenomena in live oils
, Article Journal of Molecular Liquids ; Volume 222 , 2016 , Pages 359-369 ; 01677322 (ISSN) ; Rashidi, F ; Ghazanfari, M. H ; Mousavi Dehghani, S. A ; Sharif University of Technology
Elsevier
Abstract
The thorough knowledge of the asphaltene aggregation phenomena and pressure/temperature related kinetics is helpful for accurate prediction/control of the asphaltene issues in all facets of petroleum production/processing. However, characterizing the asphaltene aggregation phenomena in live oils at high pressure-high temperature conditions is not well discussed in the available literature. In this work, the asphaltene aggregation phenomena as well as the kinetics of aggregation at different levels of pressure and temperature are investigated in light and heavy live oils using high pressure microscope. The results are presented and discussed in terms of asphaltene onset pressure, aggregates...