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1 + ϵ approximation of tree edit distance in quadratic time
, Article 51st Annual ACM SIGACT Symposium on Theory of Computing, STOC 2019, 23 June 2019 through 26 June 2019 ; 2019 , Pages 709-720 ; 07378017 (ISSN); 9781450367059 (ISBN) ; Ghodsi, M ; Hajiaghayi, M ; Seddighin, S ; Sharif University of Technology
Association for Computing Machinery
2019
Abstract
Edit distance is one of the most fundamental problems in computer science. Tree edit distance is a natural generalization of edit distance to ordered rooted trees. Such a generalization extends the applications of edit distance to areas such as computational biology, structured data analysis (e.g., XML), image analysis, and compiler optimization. Perhaps the most notable application of tree edit distance is in the analysis of RNA molecules in computational biology where the secondary structure of RNA is typically represented as a rooted tree. The best-known solution for tree edit distance runs in cubic time. Recently, Bringmann et al. show that an O(n2.99) algorithm for weighted tree edit...
3D bundles of self-assembled lanthanum hydroxide nanorods via a rapid microwave-assisted route
, Article Journal of Alloys and Compounds ; Volume 473, Issue 1-2 , 2009 , Pages 283-287 ; 09258388 (ISSN) ; Shahcheraghi, N ; Kajbafvala, A ; Zanganeh, S ; Lak, A ; Mohajerani, M. S ; Sadrnezhaad, K ; Sharif University of Technology
2009
Abstract
Three-dimensional (3D) bundles of self-assembled lanthanum hydroxide nanorods with average crystallite size of about 20 nm were fabricated via a facile and rapid microwave-assisted chemical route. The obtained material was characterized with X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations. The obtained nanorods have average diameter of about 115 nm and average length of about 730 nm. Self-assembly of primary La(OH)3 nanoparticles and their subsequent anisotropic growth along 〈2 0 0〉 direction, was proposed to be the mechanism for the formation of 3D bundles of nanorods, using TEM images. The thermal behavior of the...
3D hand pose estimation using RGBD images and hybrid deep learning networks
, Article Visual Computer ; 2021 ; 01782789 (ISSN) ; Seyedarabi, H ; Mozaffari Tazehkand, B ; Kasaei, S ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
Hand pose estimation is one of the most attractive research areas for image processing. Among the human body parts, hands are particularly important for human–machine interactions. The advent of commercial depth cameras along with the rapid growth of deep learning has made great progress in all image processing fields, especially in hand pose estimation. In this study, using depth data, we introduce two hybrid deep neural networks to estimate 3D hand poses with fewer computations and higher accuracy compared with their counterparts. Due to the fact that the dimensions of data are reduced while passing through successive layers of networks, which causes data to be lost, we use the concept of...
3D hand pose estimation using RGBD images and hybrid deep learning networks
, Article Visual Computer ; Volume 38, Issue 6 , 2022 , Pages 2023-2032 ; 01782789 (ISSN) ; Seyedarabi, H ; Mozaffari Tazehkand, B ; Kasaei, S ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Hand pose estimation is one of the most attractive research areas for image processing. Among the human body parts, hands are particularly important for human–machine interactions. The advent of commercial depth cameras along with the rapid growth of deep learning has made great progress in all image processing fields, especially in hand pose estimation. In this study, using depth data, we introduce two hybrid deep neural networks to estimate 3D hand poses with fewer computations and higher accuracy compared with their counterparts. Due to the fact that the dimensions of data are reduced while passing through successive layers of networks, which causes data to be lost, we use the concept of...
3D simulation of propagation of hydraulically driven fractures in oil reservoirs using EFG mesh-less method considering coupled hydro-mechanical effects
, Article Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014, 22 September 2014 through 25 September 2014, Kyoto ; September , 2015 , Pages 1675-1680 ; 9781138001480 (ISBN) ; Samimi, S ; Sharif University of Technology
Taylor and Francis - Balkema
2015
Abstract
Creating hydraulically induced fractures in oil/gas reservoirs is one of the methods for Enhanced Oil Recovery (EOR) that has been applied extensively in petroleum industry in recent years. Despite its popularity, the design process of Hydraulic Fracture treatment is mostly empirical based on the previous experiences gained in the oil-rich formation. The reason lies in the complexities involved in the Hydraulic Fracture process including interacting effects of fluid(s) flowand solid deformations, injection of non-Newtonian fluids in the porous media, leak-off of the injected fluid into the formation, complex geometry of the induced fracture in the intact or naturally fractured rock,...
9-Round attack on AES-256 by a 6-round property
, Article Proceedings - 2010 18th Iranian Conference on Electrical Engineering, ICEE 2010, 11 May 2010 through 13 May 2010 ; 2010 , Pages 226-230 ; 9781424467600 (ISBN) ; Soleimany, H ; Aref, M ; Sharif University of Technology
Abstract
In this paper, we propose a new 6-round Related-Key Impossible Differential property of AES-256 and two related-key impossible differential attacks on 7 and 9 round AES-256, based on the proposed property. The overall complexity of the proposed 7 round attack is decreased by the factor 217. This is for the first time that a Related-Key Impossible Differential attack on 9-round AES-256 is successful. Also this is the first related-key attack on 9-round AES-256 that needs only 2 keys. Although the data and time complexities of the attack are approximately code book and exhaustive search, but we think the proposed property will be useful in future research like boomerang and rectangle attacks
A 38 pJ/b optimal soft-MIMO detector
, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 64, Issue 9 , 2017 , Pages 1062-1066 ; 15497747 (ISSN) ; Doostnejad, R ; Mahdavi, M ; Gulak, P. G ; Sharif University of Technology
Abstract
An optimal soft multiple-input multiple-output (MIMO) detector is proposed with linear complexity for a general spatial multiplexing system with two transmitting symbols and NR 2 receiving antennas. The computational complexity of the proposed scheme is independent of the operating signal-to-noise ratio and grows linearly with the constellation order. It provides the soft maximum-likelihood solution using an efficient log-likelihood ratio calculation method, avoiding the exhaustive search on all the candidate nodes. Moreover, an efficient pipelined hardware implementation of the detection algorithm is proposed, which is fabricated and fully tested in a 130-nm CMOS technology. Operating at...
A bee colony task scheduling algorithm in computational grids
, Article Communications in Computer and Information Science, 7 July 2011 through 9 July 2011 ; Volume 188 CCIS, Issue PART 1 , July , 2011 , Pages 200-210 ; 18650929 (ISSN) ; 9783642223884 (ISBN) ; Entezari Maleki, R ; Movaghar, A ; Springer ; Sharif University of Technology
2011
Abstract
The efficient scheduling of the independent and sequential tasks on distributed and heterogeneous computing resources within grid computing environments is an NP-complete problem. Therefore, using heuristic approaches to solve the scheduling problem is a very common and also acceptable method in these environments. In this paper, a new task scheduling algorithm based on bee colony optimization approach is proposed. The algorithm uses artificial bees to appropriately schedule the submitted tasks to the grid resources. Applying the proposed algorithm to the grid computing environments, the maximum delay and finish times of the tasks are reduced. Furthermore, the total makespan of the...
A Benders decomposition for the location-allocation and scheduling model in a healthcare system regarding robust optimization
, Article Neural Computing and Applications ; 2016 , Pages 1-14 ; 09410643 (ISSN) ; Sadeghi, J ; Modarres Yazdi, M ; Sharif University of Technology
Springer-Verlag London Ltd
2016
Abstract
The hospital location and service allocation is one of the most important aspects of healthcare systems. Due to lack of studies on covering location-allocation and scheduling problems with respect to the uncertain budget, this paper develops a bi-objective hybrid model to locate hospitals and allocate machines and services scheduled. The costs of establishing facilities are assumed to be uncertain, while a robust counterpart model is employed to overcome the uncertainty. Covering the demand of each service is limited as well. Moreover, hospitals have a limited space to the specialized equipment like CT scan and MRI machines, while there is a cost constraint on hospitals and the specialized...
A Benders decomposition for the location-allocation and scheduling model in a healthcare system regarding robust optimization
, Article Neural Computing and Applications ; Volume 29, Issue 10 , 2018 , Pages 873-886 ; 09410643 (ISSN) ; Sadeghi, J ; Modarres Yazdi, M ; Sharif University of Technology
Springer London
2018
Abstract
The hospital location and service allocation is one of the most important aspects of healthcare systems. Due to lack of studies on covering location-allocation and scheduling problems with respect to the uncertain budget, this paper develops a bi-objective hybrid model to locate hospitals and allocate machines and services scheduled. The costs of establishing facilities are assumed to be uncertain, while a robust counterpart model is employed to overcome the uncertainty. Covering the demand of each service is limited as well. Moreover, hospitals have a limited space to the specialized equipment like CT scan and MRI machines, while there is a cost constraint on hospitals and the specialized...
A binary-continuous invasive weed optimization algorithm for a vendor selection problem
, Article Knowledge-Based Systems ; Volume 140 , 2018 , Pages 158-172 ; 09507051 (ISSN) ; Akhavan Niaki, T ; Sharif University of Technology
Elsevier B.V
2018
Abstract
This paper introduces a novel and practical vendor selection problem of a firm that cooperates with multiple geographically dispersed stores. In this problem, the firm entrusts some of its business process to external vendors, and each store can split the ordered quantity between one or more potential vendors, represented as a multi-sourcing strategies. Moreover, the Cobb–Douglas demand function is utilised to establish a relationship between the market demand and the selling price; representing price-sensitive demand. This paper seeks to choose the best vendors, to allocate the stores to them, and to find the optimal values for inventory-related decisions. The approach is based on the...
A bi-objective model to optimize reliability and cost of k-out-of-n series-parallel systems with tri-state components
, Article Scientia Iranica ; Volume 24, Issue 3 , 2017 , Pages 1585-1602 ; 10263098 (ISSN) ; Zaretalab, A ; Akhavan Niaki, S. T ; Pourkarim Guilani, Pa ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
Redundancy Allocation Problem (RAP) is one way to increase system reliability. In most of the models developed so far for the RAP, system components are considered to have a binary state consisting of "working perfect" or "completely failed". However, to suit the real-world applications, this assumption has been relaxed in this paper, such that components can have three states. Moreover, a Bi-Objective RAP (BORAP) is modeled for a system with serial subsystems, in which non-repairable tri-state components of each subsystem are configured in parallel and the subsystem works under k-out-of-n policy. Furthermore, to enhance system reliability, technical and organizational activities that can...
A brief survey on pure cohen–macaulayness in a fixed codimension
, Article Acta Mathematica Vietnamica ; 2021 ; 02514184 (ISSN) ; Poursoltani, M ; Terai, N ; Yassemi, S ; Sharif University of Technology
Springer
2021
Abstract
A concept of Cohen–Macaulay in codimension t is defined and characterized for arbitrary finitely generated modules and coherent sheaves by Miller, Novik, and Swartz in 2011. Soon after, Haghighi, Yassemi, and Zaare-Nahandi defined and studied CMt simplicial complexes, which is the pure version of the abovementioned concept and naturally generalizes both Cohen–Macaulay and Buchsbaum properties. The purpose of this paper is to survey briefly recent results of CMt simplicial complexes. © 2021, Institute of Mathematics, Vietnam Academy of Science and Technology (VAST) and Springer Nature Singapore Pte Ltd
A brief survey on pure cohen–macaulayness in a fixed codimension
, Article Acta Mathematica Vietnamica ; Volume 47, Issue 1 , 2022 , Pages 181-196 ; 02514184 (ISSN) ; Poursoltani, M ; Terai, N ; Yassemi, S ; Sharif University of Technology
Springer
2022
Abstract
A concept of Cohen–Macaulay in codimension t is defined and characterized for arbitrary finitely generated modules and coherent sheaves by Miller, Novik, and Swartz in 2011. Soon after, Haghighi, Yassemi, and Zaare-Nahandi defined and studied CMt simplicial complexes, which is the pure version of the abovementioned concept and naturally generalizes both Cohen–Macaulay and Buchsbaum properties. The purpose of this paper is to survey briefly recent results of CMt simplicial complexes. © 2021, Institute of Mathematics, Vietnam Academy of Science and Technology (VAST) and Springer Nature Singapore Pte Ltd
A combinational adaptive noise canceller using filter bank
, Article 6th International Symposium on Image and Signal Processing and Analysis, ISPA 2009, Salzburg, 16 September 2009 through 18 September 2009 ; 2009 , Pages 71-74 ; 9789531841351 (ISBN) ; Hejazi, A ; Akhaee, M. A ; Eshghi, M ; Sharif University of Technology
2009
Abstract
This paper proposes a novel combinational Adaptive Noise Canceller (ANC), which is suitable for non stationary noise environments. Pre-filter bank structure improves the convergence rate leading to less error in real-time applications. During our investigations, we have found out adaptive algorithms have better performance for low frequency subbands. Thus, by using Singular Value Decomposition (SVD) in each subband, a simplified version of variable step-size algorithms has been employed in low frequency subbands; while for high frequency subbands, some conventional techniques have been used. Simulation results show that combination of adaptive and conventional methods have better performance...
A compact low power mixed-signal equalizer for gigabit ethernet applications
, Article ISCAS 2006: 2006 IEEE International Symposium on Circuits and Systems, Kos, 21 May 2006 through 24 May 2006 ; 2006 , Pages 5167-5170 ; 02714310 (ISSN); 0780393902 (ISBN); 9780780393905 (ISBN) ; Eghbalkhah, B ; Saeedi, S ; Afzali Kusha, A ; Atarodi, M ; Sharif University of Technology
2006
Abstract
In this paper we propose a novel structure of a discrete-time mixed-signal linear equalizer designed for analog front end of Gigabit Ethernet receivers. The circuit is an FIR filter which involves 6 taps based on a coefficient-rotating structure. Here, a simple structure is used for merging digital to analog conversion of the filter's coefficients and multipliers needed for 6 taps. This structure results in high speed and low power dissipation as well as less A/D converter complexity. Simulated in a 0.18 um CMOS technology, this equalizer operates at 125 MHz while dissipating 10 mw from a 1.8 V power supply. © 2006 IEEE
A comparative study of different approaches for finding the upper boundary points in stochastic-flow networks
, Article International Journal of Enterprise Information Systems ; Volume 10, Issue 3 , 1 July , 2014 , Pages 13-20 ; ISSN: 15481115 ; Nasseri, S. H ; Forghani Elahabad, M ; Ebrahimnejad, A ; Sharif University of Technology
Abstract
An information system network (ISN) can be modeled as a stochastic-flow network (SFN). There are several algorithms to evaluate reliability of an SFN in terms of Minimal Cuts (MCs). The existing algorithms commonly first find all the upper boundary points (called d-MCs) in an SFN, and then determine the reliability of the network using some approaches such as inclusion-exclusion method, sum of disjoint products, etc. However, most of the algorithms have been compared via complexity results or through one or two benchmark networks. Thus, comparing those algorithms through random test problems can be desired. Here, the authors first state a simple improved algorithm. Then, by generating a...
A comparative study of energy/power consumption in parallel decimal multipliers
, Article Microelectronics Journal ; Vol. 45, Issue 6 , June , 2014 , pp. 775-780 ; Ejlali, A ; Gorgin, S ; Sharif University of Technology
Abstract
Decimal multiplication is a frequent operation with inherent complexity in implementation. Commercial and financial applications require working with decimal numbers while it has been shown that if we convert decimal number to binary ones, this will negatively influence the preciseness required for these applications. Existing research works on parallel decimal multipliers have mainly focused on latency and area as two major factors to be improved. However, energy/power consumption is another prominent issue in today's digital systems. While the energy consumption of parallel decimal multipliers has not been addressed in previous works, in this paper we present a comparative study of...
A comparison between disturbance observer-based and model-based control of needle in percutaneous applications
, Article IECON Proceedings (Industrial Electronics Conference), 25 October 2012 through 28 October 2012 ; October , 2012 , Pages 2104-2108 ; 9781467324212 (ISBN) ; Jahed, M ; The Institute of Electrical and Electronics Engineers (IEEE); IEEE Industrial Electronics Society (IES) ; Sharif University of Technology
2012
Abstract
In this paper, model-based and distrbance observer (DOB)-based control of needle in precautious applications are compared. In the model-based approach, the force acting on the needle is calculated by evaluating the finite element model (FEM) of the tissue with the tissue deformation. In DOB-based method, the force acting on the needle is considered as an external disturbance and it is estimated using position and velocity of the needle. In both approaches, the calculated/estimated force is used in a sliding mode control scheme to steer the needle to the target. A dynamics equation for the movement of the needle is proposed which includes the force applied by the tissue to the needle. The...
A comparison of metric-based and empirical approaches for cognitive analysis of modeling languages
, Article Fundamenta Informaticae ; Volume 90, Issue 3 , 2009 , Pages 337-352 ; 01692968 (ISSN) ; Habibi, J ; Sharif University of Technology
2009
Abstract
Modeling languages are needed to describe the conceptual construct underlying software. Several modeling languages have been proposed during the last decades. Cognitive complexity is one of the common problems in designing modeling languages. Users have to split their attention and cognitive resources between two different tasks when working with complex language: solving the problem and understanding the elements composing the language. Several researches have been accomplished to evaluate cognitive complexity of modeling languages, among them, metric based and empirical approaches aremore important and convenient than others. In this paper, we compared these two methods. Results show that...