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Biologically inspired spiking neurons: Piecewise linear models and digital implementation
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 59, Issue 12 , 2012 , Pages 2991-3004 ; 15498328 (ISSN) ; Ahmadi, A ; Bavandpour, M ; Sharif University of Technology
2012
Abstract
There has been a strong push recently to examine biological scale simulations of neuromorphic algorithms to achieve stronger inference capabilities. This paper presents a set of piecewise linear spiking neuron models, which can reproduce different behaviors, similar to the biological neuron, both for a single neuron as well as a network of neurons. The proposed models are investigated, in terms of digital implementation feasibility and costs, targeting large scale hardware implementation. Hardware synthesis and physical implementations on FPGA show that the proposed models can produce precise neural behaviors with higher performance and considerably lower implementation costs compared with...
Modeling the effect of process variations on the delay and power of the digital circuit using fast simulators
, Article 2013 21st Iranian Conference on Electrical Engineering, ICEE 2013 ; 2013 , 14-16 May ; 9781467356343 (ISBN) ; Soleimani, H ; Ahmadi, A ; Bavandpour, M ; Zwolinski, M ; Sharif University of Technology
2013
Abstract
Process variation has an increasingly dramatic effect on delay and power as process geometries shrink. Even if the amount of variation remains the same as in previous generations, it accounts for a greater percentage of process geometries as they get smaller. So an accurate prediction of path delay and power variability for real digital circuits in the current technologies is very important; however, its main drawback is the high runtime cost. In this paper, we present a new fast EDA tool which accelerates Monte Carlo based statistical static timing analysis (SSTA) for complex digital circuit. Parallel platforms like Message Passing Interface and POSIX® Threads and also the GPU-based CUDA...
A GPU based simulation platform for adaptive frequency Hopf oscillators
, Article ICEE 2012 - 20th Iranian Conference on Electrical Engineering ; 2012 , Pages 884-888 ; 9781467311489 (ISBN) ; Maleki, M. A ; Ahmadi, A ; Bavandpour, M ; Maharatna, K ; Zwolinski, M ; Sharif University of Technology
2012
Abstract
In this paper we demonstrate a dynamical system simulator that runs on a single GPU. The model (running on an NVIDIA GT325M with 1GB of memory) is up to 50 times faster than a CPU version when more than 10 million adaptive Hopf oscillators have been simulated. The simulation shows that the oscillators tune to the correct frequencies for both discrete and continuous spectra. Due to its dynamic nature the system is also capable to track non-stationary spectra. With the help of this model the frequency spectrum of an ECG signal (as a non-stationary signal) obtained and was showed that frequency domain representation of signal (i.e. FFT) is the same as one MATLAB generates
Class attention map distillation for efficient semantic segmentation
, Article 1st International Conference on Machine Vision and Image Processing, MVIP 2020, 19 February 2020 through 20 February 2020 ; Volume 2020-February , 2020 ; Kasaei, S ; Sharif University of Technology
IEEE Computer Society
2020
Abstract
In this paper, a novel method for capturing the information of a powerful and trained deep convolutional neural network and distilling it into a training smaller network is proposed. This is the first time that a saliency map method is employed to extract useful knowledge from a convolutional neural network for distillation. This method, despite of many others which work on final layers, can successfully extract suitable information for distillation from intermediate layers of a network by making class specific attention maps and then forcing the student network to mimic producing those attentions. This novel knowledge distillation training is implemented using state-of-the-art DeepLab and...
Implementation of Spiking Neural Networks on Memristive Crossbar Structure
, M.Sc. Thesis Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor)
Abstract
Hardware implementation of Spiking Neural Networks (SNN) can bring about a fast and low cost neural network which has more biological support. Memristor nanodevices are most proposed devices for use as synapses to add dynamic learning to SNNs because of their nano-scale dimensions, low power consumption and memory property. One of the most important bottlenecks in the memristor crossbar based SNNs is system-level simulation of learning process due to its huge memristor equations that should be solved for each sample of time. Due to parallel computation capability of our simulation work, we simulate the circuit on single core CPU and then proposed high performance parallel platforms as...
Class Attention Map Distillation In Semantic Segmentation
, M.Sc. Thesis Sharif University of Technology ; Kasaei, Shohreh (Supervisor)
Abstract
Semantic segmentation is the tash of labeling each pixel of an input image. It is one of the main problems in computer vision and plays an important role in scene understanding. State of the art methods of solving it are based on Convolutional Neural Networhs (CNNs). While many real world tasks like autodriving cars and robot navigation require fast and lightweight models, CNNs inherently tend to give beter accuracy when they are deeper and bigger, and this has raised interest in designing compact networks. Knowledge distillation is one of the popular methods of training compact networhs and helps to transfer a big and powerful network’s knowledge to a small and compact one. In this research...
Networked adaptive non-linear oscillators: A digital synthesis and application
, Article Circuits, Systems, and Signal Processing ; Vol. 34, Issue. 2 , 2014 , pp. 483-512 ; ISSN: 1531-5878 ; Ahmadi, A ; Makki, S. V. A. - D ; Soleimani, H ; Bavandpour, M ; Sharif University of Technology
2014
Abstract
This paper presents a digital hardware implementation of a frequency adaptive Hopf oscillator along with investigation on systematic behavior when they are coupled in a population. The mathematical models of the oscillator are introduced and compared in sense of dynamical behavior by using system-level simulations based on which a piecewise-linear model is developed. It is shown that the model is capable to be implemented digitally with high efficiency. Behavior of the oscillators in different network structures to be used for dynamic Fourier analysis is studied and a structure with more precise operation which is also more efficient for FPGA-based implementation is implemented. Conceptual...
Spiking neuro-fuzzy clustering system and its memristor crossbar based implementation
, Article Microelectronics Journal ; Vol. 45, issue. 11 , 2014 , pp. 1450-1462 ; ISSN: 00262692 ; Bagheri-Shouraki, S ; Soleimani, H ; Ahmadi, A ; Linares-Barranco, B ; Sharif University of Technology
2014
Abstract
This study proposes a spiking neuro-fuzzy clustering system based on a novel spike encoding scheme and a compatible learning algorithm. In this system, we utilize an analog to binary encoding scheme that properly maps the concept of "distance" in multi-dimensional analog spaces to the concept of "dissimilarity " of binary bits in the equivalent binary spaces. When this scheme is combined with a novel binary to spike encoding scheme and a proper learning algorithm is applied, a powerful clustering algorithm is produced. This algorithm creates flexible fuzzy clusters in its analog input space and modifies their shapes to different convex shapes during the learning process. This system has...
Simulation of memristor crossbar structure on GPU platform
, Article ICEE 2012 - 20th Iranian Conference on Electrical Engineering, 15 May 2012 through 17 May 2012 ; May , 2012 , Pages 178-183 ; 9781467311489 (ISBN) ; Shouraki, S. B ; Soleimani, H ; Ahmadi, A ; Makhlooghpour, A. A ; Sharif University of Technology
2012
Abstract
Memristive devices have gained significant research attention lately because of their unique properties and wide application spectrum. In particular, memristor-based resistive random access memory (RRAM) offers the high density, low power, and low volatility required for next-generation nonvolatile memory. Nowadays, despite significant advances in hardware technology, in the case of massively parallel systems still new computational architectures are required. Simulation of large quantity of memristors in the crossbar structure is a known challenge encountering these barriers. Using graphic processing units (GPU) as a low-cost and high-performance computing platform is an efficient preferred...
Cellular Memristive Dynamical Systems (CMDS)
, Article International Journal of Bifurcation and Chaos ; Vol. 24, issue. 5 , May , 2014 ; Soleimani, H ; Bagheri-Shouraki, S ; Ahmadi, A ; Abbott, D ; Chua, L. O ; Sharif University of Technology
2014
Abstract
This study presents a cellular-based mapping for a special class of dynamical systems for embedding neuron models, by exploiting an efficient memristor crossbar-based circuit for its implementation. The resultant reconfigurable memristive dynamical circuit exhibits various bifurcation phenomena, and responses that are characteristic of dynamical systems. High programmability of the circuit enables it to be applied to real-time applications, learning systems, and analytically indescribable dynamical systems. Moreover, its efficient implementation platform makes it an appropriate choice for on-chip applications and prostheses. We apply this method to the Izhikevich, and FitzHugh-Nagumo neuron...
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...