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A new non-dimensional parameter to obtain the minimum mixing length in tree-like concentration gradient generators
, Article Chemical Engineering Science ; Volume 195 , 2019 , Pages 120-126 ; 00092509 (ISSN) ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Microfluidic-based concentration gradient generators (CGGs) have a number of applications in chemical, biological and pharmaceutical studies. Thus, precise design of the microfluidic system is crucial to maintaining the desired concentration gradient in microchannels. One of the design considerations is the length of microchannels in the structure of a CGG. A CGG with a short length fails to provide the complete diffusive mixing, while the size of the microchip would unfavorably increase by incorporating a long CGG. Considering a CGG as a tree-like structure consisting of T-shaped micromixers, the mixing process of the species at a straight microchannel has been solved analytically. Herein,...
A microfluidic concentration gradient generator for simultaneous delivery of two reagents on a millimeter-sized sample
, Article Journal of Flow Chemistry ; Volume 10, Issue 4 , 2020 , Pages 615-625 ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
Springer International Publishing
2020
Abstract
Microfluidic concentration gradient generators (μCGGs) are indispensable parts of many emerging lab-on-a-chip platforms for biological studies and drug delivery applications. Most of the μCGGs reported in the literature can only generate the desired concentration gradients in a micron-sized sample (e.g., cells). As such, there is an unmet need to design a μCGG that can generate continuous concentration gradients of multi reagents (e.g., drugs) in a millimeter-sized sample (e.g., tissue). Herein, we report the proof-of-concept of this class of μCGG by combining a modified tree-like CGG with a micromixer. By conducting both experimental investigation and numerical analysis, we show that the...
An alternative mechanism for the formation of high density lipoprotein in peripheral tissue
, Article Scientia Iranica ; Volume 23, Issue 2 , 2016 , Pages 600-608 ; 10263098 (ISSN) ; Saidi, M. S ; Rismanian, M ; Firoozabadi, B ; Amininasab, M ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
High Density Lipoprotein (HDL) is a lipid-protein complex responsible for transporting cholesterol and triglyceride molecules, as these compounds are unable to dissolve in aqueous environments such as a bloodstream. Among the most well-known possible structures, the belt-like structure is the most common shape proposed for this vital bimolecular complex. In this structure, the protein scaffold encompasses the lipid bilayer and a planar circular structure is formed. Several HDL simulations with embedded components in the lipid section were performed. Here, we applied a series of molecular dynamic simulations using the MARTINI coarse grain force field to investigate an HDL model, with pores of...
Investigation of the effect of walkway orientation on natural ventilation
, Article Scientia Iranica ; Volume 23, Issue 2 , 2016 , Pages 678-684 ; 10263098 (ISSN) ; Forughi, A. F ; Vesali, F ; Mahmoodabadi, M. S ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
Proper orientation of walkways, based on regional winds and local shade, provides good control over walkway ventilation. The architecture of the old town of Sirjan had experimentally orientated the city's walkways in such a manner that the shadows in the walkways produced the maximum possible natural ventilation in this hot and dry town. This study has focused on the optimum design of Sirjan city considering a natural ventilation mechanism. At first, a typical walkway with certain geometric parameters is considered. Then, considering the symmetry of the shadows cast in the walkway, the natural ventilation rate is investigated at 7 different angles and at 15° intervals. The problem is modeled...
Organ-tumor-on-a-chip for chemosensitivity assay: A critical review
, Article Micromachines ; Volume 7, Issue 8 , 2016 ; 2072666X (ISSN) ; Nikmaneshi, M. R ; Moghadas, H ; Kiyoumarsi Oskouei, A ; Rismanian, M ; Barisam, M ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
MDPI AG
2016
Abstract
With a mortality rate over 580,000 per year, cancer is still one of the leading causes of death worldwide. However, the emerging field of microfluidics can potentially shed light on this puzzling disease. Unique characteristics of microfluidic chips (also known as micro-total analysis system) make them excellent candidates for biological applications. The ex vivo approach of tumor-on-a-chip is becoming an indispensable part of personalized medicine and can replace in vivo animal testing as well as conventional in vitro methods. In tumor-on-a-chip, the complex three-dimensional (3D) nature of malignant tumor is co-cultured on a microfluidic chip and high throughput screening tools to evaluate...
Molecular Dynamics Simulation of Protein Channels
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Saeed (Supervisor) ; Firoozabadi, Bahar (Supervisor)
Abstract
By studying change of ion concentrations in animal cells, researchers have reach to important information about cell cycles such as cell growth, muscle cell contraction and cell migration. Manner and amount of passage of ions through cell membrane are basic information that for studying the cell cycle is required. In this thesis, by using two methods, Forward-Reverse constant velocity Steered Molecular Dynamics (FR-cv-SMD) and classical Equilibrium Molecular Dynamics (EMD), diffusion coefficient and Potential of Mean Force (PMF) of sodium and potassium permeation through their protein channels are obtained. For verification the molecular dynamics (MD) methods, diffusion coefficient of K+...
Design and Fabrication of a Microfluidic System for Simultaneous Delivery of Two Reagents on a Millimeter-Sized Tissue
, Ph.D. Dissertation Sharif University of Technology ; Saeedi, Mohamad Saeed (Supervisor) ; Kashaninejad, Navid (Co-Supervisor)
Abstract
It is of great interest to investigate the effects of different concentrations of chemical species on the behavior of test samples. For example, while developing a new drug, pharmacologists are concerned with the behavior of the live sample against different drug concentrations. Microfluidic systems are the new engineering platforms developed for simplifying these experiments. The main goal of the current study is the design and fabrication of a microfluidic system with the capability of generating a continuous concentration gradient from two species simultaneously on a millimeter-sized test sample. Such a system creates many benefits for researchers using microfluidics technology. Our...
Probability of missed detection as a criterion for receiver placement in MIMO PCL
, Article IEEE National Radar Conference - Proceedings, 7 May 2012 through 11 May 2012, Atlanta, GA ; 2012 , Pages 0924-0927 ; 10975659 (ISSN) ; 9781467306584 (ISBN) ; Chitgarha, M. M ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
IEEE
2012
Abstract
Using multiple antennas at the transmit and receive sides of a passive radar brings both the benefits of MIMO radar and passive radar. However one of the obstacles arisen in such configuration is the receive antennas placement in proper positions so that the radar performance is improved. Here we just consider the case of positioning one receiver among multiple illuminators of opportunity. Indeed it is a start for the solution of optimizing the geometry of the multiple receivers in a passive radar
An efficient method for the ring opening of epoxides with aromatic amines by Sb(III) chloride under microwave irradiation
, Article Journal of Chemical Research ; Issue 4 , 2008 , Pages 220-221 ; 03082342 (ISSN) ; Hashemi, M. M ; Mottaghi, M. M ; Foroughi, M. M ; Sharif University of Technology
2008
Abstract
SbCl3 supported on montmorillonite K-10 is an efficient catalyst for the ring opening of epoxides with aromatic amines under solvent-free conditions and microwave irradiation to give the corresponding b-amino alcohols in high yields with high regioselectivity
Resource allocation for uav-enabled integrated sensing and communication (isac) via multi-objective optimization
, Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings ; Volume 2023-June , 2023 ; 15206149 (ISSN); 978-172816327-7 (ISBN) ; Naghsh, M. M ; Karbasi, M ; Nayebi, M. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2023
Abstract
In this paper, we consider an integrated sensing and communication (ISAC) system with wireless power transfer (WPT) where an unmanned aerial vehicle (UAV)-based radar serves a group of energy-limited communication users in addition to its sensing functionality. In this architecture, the radar senses the environment in phase 1 (namely sensing phase) and mean-while, the communications users (nodes) harvest and store the energy from the radar transmit signal. The stored energy is then used for information transmission from the nodes to UAV in phase 2, i.e., uplink phase. Performance of the radar system depends on the transmit signal as well as the receive filter; the energy of the transmit...
MIMO radar signal design to improve the MIMO ambiguity function via maximizing its peak
, Article Signal Processing ; Volume 118 , 2016 , Pages 139-152 ; 01651684 (ISSN) ; Radmard, M ; Nazari Majd, M ; Karbasi, S. M ; Nayebi, M. M ; Sharif University of Technology
Elsevier
2016
Abstract
One of the important obstacles in MIMO (Multiple Input Multiple Output) radars is the issue of designing proper transmit signals. Indeed, the capability of signal design is a significant advantage in MIMO radars, through which, the system can achieve much better performance. Many different aspects of this performance improvement have been considered yet, and the transmit signals have been designed to attain such goal, e.g., getting higher SNR or better detector's performance at the receiver. However, an important tool for evaluating the radar's performance is its ambiguity function. In this paper, we consider the problem of transmit signal design, in order to optimize the ambiguity function...
Detection-localization tradeoff in MIMO radars
, Article Radioengineering ; Volume 26, Issue 2 , 2017 , Pages 581-587 ; 12102512 (ISSN) ; Radmard, M ; Chitgarha, M. M ; Bastani, M. H ; Nayebi, M. M ; Sharif University of Technology
2017
Abstract
Two gains play key roles in recently developed MIMO wireless communication systems: "spatial diversity" gain and "spatial multiplexing" gain. The diversity gain refers to the capability to decrease the error rate of the MIMO channel, while the multiplexing gain implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the diversity gain) and increasing data rate (via an increase in the multiplexing gain). On the other hand, recently, MIMO radars have attracted much attention for their superior ability to enhance...
Antenna placement and power allocation optimization in MIMO detection
, Article IEEE Transactions on Aerospace and Electronic Systems ; Vol. 50, Issue 2 , April , 2014 , pp. 1468-1478 ; Chitgarha, M. M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
2014
Abstract
It is a well known fact that using multiple antennas at transmit and receive sides improves the detection performance. However, in such multiple-input multiple-output (MIMO) configuration, proper positioning of transmitters and receivers is a big challenge that can have significant influence on the performance of the overall system. In addition, determining the power of each transmitter under a total power constraint is a problem that should be solved in order to enhance the performance and coverage of such a system. In this paper, we design the Neyman-Pearson detector under the Rayleigh scatter model and use it to introduce a criterion for the antenna placement at both transmit and receive...
Ambiguity function of MIMO radar with widely separated antennas
, Article Proceedings International Radar Symposium ; 16 -18 June , 2014 ; ISSN: 21555753 ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
2014
Abstract
There has been much interest, recently, towards exploiting the Multiple-Input Multiple-Output (MIMO) technique in radar. It is shown that using multiple antennas at transmit and receive sides can improve the performance of the system. However, in order to analyze the system's performance, its ambiguity function, i.e. the ambiguity function of a MIMO radar, is needed to be defined. In this paper, beginning from the information theoretic definitions, we derive such function, specifically for a MIMO radar with widely separated antennas
Choosing the position of the receiver in a MISO passive radar system
, Article European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 9th European Radar Conference, EuRAD 2012 ; 2012 , Pages 318-321 ; 9782874870293 (ISBN) ; Majd, M. N ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
2012
Abstract
By combining the two ideas of MIMO (Multiple Input Multiple Output) and PCL (Passive Coherent Location) in radar, one can achieve the advantages of both recently developed techniques simultaneously. While using multiple antennas at the receive side provides a spatial diversity of the object to be detected, using multiple illuminators of opportunity, most importantly, makes the radar covert to the interceptors. One obstacle in such MIMO configuration is choosing the positions of the receive antennas. In this paper, after analyzing the Neyman-Pearson detector for the DVB-T based PCL, we introduce the probability of missed detection as a criterion to place the receive antenna. Here, we only...
Adaptive filtering techniques in passive radar
, Article Proceedings International Radar Symposium, Dresden ; Volume 2 , June , 2013 , Pages 1067-1078 ; 21555753 (ISSN) ; 9783954042234 (ISBN) ; Radmard, M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
2013
Abstract
One of the most important obstacles in passive radar applications is removing the direct signal from the target channel. Otherwise, week echoes from the targets in the target channel would be ignored due to the limited dynamic range of the system. One of the most effective techniques in this field is using adaptive filters. In this paper various adaptive filters are introduced and their performances are shown and compared
Ambiguity function based receiver placement in multi-site radar
, Article 2016 CIE International Conference on Radar, RADAR 2016, 10 October 2016 through 13 October 2016 ; 2017 ; 9781509048281 (ISBN) ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
2017
Abstract
It has been shown that using multiple antennas in a radar system improves the performance considerably, since multiple target echoes are received from different aspect angles of the target. In this way, the target detection is improved. However, when using multiple antennas, some problems, such as designing the transmit signals, synchronization, etc. emerge that should be solved. One of such problems is the receiver placement. Receiver placement deals with choosing a proper position for the receive antenna in order to optimize the whole system's performance. In this paper, a receiver placement procedure based on improving the radar ambiguity function is proposed for the case of a multisite...
Improving MIMO radar's performance through receivers' positioning
, Article IET Signal Processing ; Volume 11, Issue 5 , 2017 , Pages 622-630 ; 17519675 (ISSN) ; Radmard, M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
Institution of Engineering and Technology
2017
Abstract
By employing the MIMO (multiple-input-multiple-output) technology in radar, some new problems emerged, that, in order to benefit the MIMO gains in radar, it was necessary to solve them suitably. One of such obstacles is determining the positions of receive antennas in a MIMO radar system with widely separated antennas (WS MIMO radar), since it is shown that the antennas' positions affect the whole system's performance considerably. In this study, a proper receivers' positioning procedure is proposed. To do this end, four criteria are developed based on the proposed MIMO detector and the MIMO ambiguity function. The simulations verify that the proposed positioning procedure improves the...
Silylation of hydroxy groups with HMDS under microwave irradiation and solvent-free conditions
, Article Phosphorus, Sulfur and Silicon and Related Elements ; Volume 177, Issue 2 , 2002 , Pages 289-292 ; 10426507 (ISSN) ; Saidi, M. R ; Bolourtchian, M ; Heravi, M. M ; Sharif University of Technology
2002
Abstract
Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields
Dynamic analysis of carbon nanotubes under electrostatic actuation using modified couple stress theory
, Article Acta Mechanica ; Vol. 225, Issue 6 , June , 2014 , pp. 1523-1535 ; Online ISSN: 1619-6937 ; Rastgoo, A ; Ahmadian, M. T ; Mashhadi, M. M ; Sharif University of Technology
2014
Abstract
Modified couple stress theory is a size-dependent theorem capturing the micro/nanoscale effects influencing the mechanical behaviors of the micro- and nanostructures. In this paper, it is applied to investigate the nonlinear vibration of carbon nanotubes under step DC voltage. The vibration, natural frequencies and dynamic pull-in characteristics of the carbon nanotubes are studied in detail. Moreover, the effects of various boundary conditions and geometries are scrutinized on the dynamic characteristics. The results reveal that application of this theory leads to the higher values of the natural frequencies and dynamic pull-in voltages