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K/K-Nearest Neighborhood criterion for improving locally linear embedding
, Article Proceedings of the 2009 6th International Conference on Computer Graphics, Imaging and Visualization: New Advances and Trends, CGIV2009, 11 August 2009 through 14 August 2009, Tianjin ; 2009 , Pages 392-397 ; 9780769537894 (ISBN) ; Moghaddam, H. A ; Babaie Zadeh, M ; Sharif University of Technology
Abstract
Spectral manifold learning techniques have recently found extensive applications in machine vision. The common strategy of spectral algorithms for manifold learning is exploiting the local relationships in a symmetric adjacency graph, which is typically constructed using k-nearest neighborhood (k-NN) criterion. In this paper, with our focus on locally linear embedding as a powerful and well-known spectral technique, shortcomings of k-NN for construction of the adjacency graph are first illustrated, and then a new criterion, namely k/K-nearest neighborhood (k/K-NN) is introduced to overcome these drawbacks. The proposed criterion involves finding the sparsest representation of each sample in...
Numerical simulation of the behavior of toroidal and spheroidal multicellular aggregates in microfluidic devices with microwell and U-shaped barrier
, Article Micromachines ; Volume 8, Issue 12 , 2017 ; 2072666X (ISSN) ; Saidi, M. S ; Kashaninejad, N ; Vadivelu, R ; Nguyen, N. T ; Sharif University of Technology
Abstract
A microfluidic system provides an excellent platform for cellular studies. Most importantly, a three-dimensional (3D) cell culture model reconstructs more accurately the in vivo microenvironment of tissue. Accordingly, microfluidic 3D cell culture devices could be ideal candidates for in vitro cell culture platforms. In this paper, two types of 3D cellular aggregates, i.e., toroid and spheroid, are numerically studied. The studies are carried out for microfluidic systems containing U-shaped barrier as well as microwell structure. For the first time, we obtain oxygen and glucose concentration distributions inside a toroid aggregate as well as the shear stress on its surface and compare its...
Systematic computation of nonlinear bilateral dynamical systems with a novel low-power log-domain circuit
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 64, Issue 8 , 2017 , Pages 2013-2025 ; 15498328 (ISSN) ; Soleimani, H ; Drakakis, E. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Simulation of large-scale nonlinear dynamical systems on hardware with a high resemblance to their mathematical equivalents has been always a challenge in engineering. This paper presents a novel current-input current-output circuit supporting a systematic synthesis procedure of log-domain circuits capable of computing bilateral dynamical systems with considerably low power consumption and acceptable precision. Here, the application of the method is demonstrated by synthesizing four different case studies: 1) a relatively complex 2-D nonlinear neuron model; 2) a chaotic 3-D nonlinear dynamical system Lorenz attractor having arbitrary solutions for certain parameters; 3) a 2-D nonlinear Hopf...
Perspective reconstruction of non-rigid surfaces from single-view videos
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 1452-1458 ; 9781509059638 (ISBN) ; Kasaei, S ; Sharif University of Technology
Abstract
A novel algorithm to reconstruct the three-dimensional (3D) structure of non-rigid shapes based on a single view video, considering the perspective projection camera model, is presented in this paper. Even though perspective projection is considered to be the most realistic model and is ideal for a wide range of cameras in machine vision applications, but because of its complex and often non-linear equations, mostly, is approximated by some simpler camera projection models such as orthographic projection, weak perspective projection and so forth. Orthographic reconstruction of non-rigid surfaces has been done by singular value decomposition algorithm and using the orthogonal characteristics...
Derivation of a low-frequency model for a 3D wound core transformer
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 1319-1323 ; 9781509059638 (ISBN) ; Hajipour, E ; Moradnouri, A ; Vakilian, M ; Sharif University of Technology
Abstract
3D wound core is a newly proposed core structure, which is used for construction of distribution transformers. Although many advantages have been proposed for transformer with 3D wound core and it has found increasing application in some countries such as China and Iran, no model has been presented so far in the literature for such transformers. In this paper, a low frequency model, derived based on the duality principle for transformer with 3D wound core, which can be used for both steady state and low-frequency transient studies. The validity of the model in steady state condition is then verified by experimental results. © 2017 IEEE
Human interaction with IoT-based smart environments
, Article Multimedia Tools and Applications ; Volume 76, Issue 11 , 2017 , Pages 13343-13365 ; 13807501 (ISSN) ; Semsar, A ; Sharif University of Technology
Springer New York LLC
2017
Abstract
This paper describes concepts, design, implementation, and performance evaluation of a 3D-based user interface for accessing IoT-based Smart Environments (IoT-SE). The generic interaction model of the described work addresses some major challenges of Human-IoT-SE-Interaction such as cognitive overload associated with manual device selection in complex IoT-SE, loss of user control, missing system image or over-automation. To address these challenges we propose a 3D-based mobile interface for mixed-initiative interaction in IoT-SE. The 3D visualization and 3D UI, acting as the central feature of the system, create a logical link between physical devices and their virtual representation on the...
Inverse vibration technique for structural health monitoring of offshore jacket platforms
, Article Applied Ocean Research ; Volume 62 , 2017 , Pages 181-198 ; 01411187 (ISSN) ; Lotfi, A ; Dolatshahi, K. M ; Golafshani, A. A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In this paper a new approach is introduced for structural health monitoring of offshore jacket platforms. The procedure uses the measured ambient vibration responses and the corresponding readable natural frequencies and mode shapes of the structural system. Since offshore platforms are composed of heavy topsides supported by jacket structures, participation of the first mode is dominant in each direction in the response of the structure under field excitations. Moreover, ambient vibrations such as wave loads and boat impacts only excite the first modes of the structure. Therefore, it is difficult to find higher modes and the pertinent frequencies by use of accelerometers data. The...
Neda: supporting direct inter-core neighbor data exchange in GPUs
, Article IEEE Computer Architecture Letters ; Volume 17, Issue 2 , 2018 , Pages 225-229 ; 15566056 (ISSN) ; Sadrosadati, M ; Falahati, H ; Barkhordar, M ; Sarbazi Azad, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Image processing applications employ various filters for several purposes, such as enhancing the images and extracting the features. Recent studies show that filters in image processing applications take a substantial amount of the execution time, and it is crucial to boost their performance to improve the overall performance of the image processing applications. Image processing filters require a significant amount of data sharing among threads which are in charge of filtering neighbor pixels. Graphics Processing Units (GPUs) attempt to satisfy the demand of data sharing by providing the scratch-pad memory, shuffle instructions, and on-chip caches. However, we observe that these mechanisms...
Design-oriented modelling of axial-flux variable-reluctance resolver based on magnetic equivalent circuits and Schwarz-Christoffel mapping
, Article IEEE Transactions on Industrial Electronics ; Volume 65, Issue 5 , May , 2018 , Pages 4322-4330 ; 02780046 (ISSN) ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Axial flux variable reluctance (AFVR) resolvers have substantial benefits that make them suitable for motion control drives. However, they suffer from insufficient accuracy, especially in high-accuracy applications. Hence, optimizing the AFVR resolver structure is necessary for improving its commercial usage. However, its accurate modelling needs three-dimensional (3-D) time stepping finite element analysis (TSFEA) that is computationally expensive and unsuitable for co-usage with optimization algorithms. The aim of this paper is to establish an accurate, yet computationally fast, model suitable for optimal design of AFVR resolvers. The working of the proposed model is based on magnetic...
Similarity measures for intersection of camera view frustums
, Article Iranian Conference on Machine Vision and Image Processing, MVIP ; Volume 2017-November , 2018 , Pages 171-175 ; 21666776 (ISSN); 9781538644041 (ISBN) ; Shirzad, H ; Kasaei, S ; Sharif University of Technology
IEEE Computer Society
2018
Abstract
For a moving camera recognizing that it has seen a place before now, is one the most important issues in the 3D reconstruction problems. In these problems, the main goal is to create a three-dimensional model from a sequence of 2D captured images during different times. That part of the scene which is rendered by a camera is often modeled by a frustum. Calculating the amount of intersection of two camera view frustums at different times can help to solve this problem. However, there are two major difficulties. First, calculating the intersection of two frustums, in general, is so complicated. And second, there are some uncertainties in the moving camera parameters over time. In this paper,...
LTRF: enabling high-capacity register files for GPUs via hardware/software cooperative register prefetching
, Article 23rd International Conference on Architectural Support for Programming Languages and Operating Systems, ASPLOS 2018, 24 March 2018 through 28 March 2018 ; 2018 , Pages 489-502 ; 9781450349116 (ISBN) ; Mirhosseini, A ; Ehsani, S. B ; Sarbazi Azad, H ; Drumond, M ; Falsafi, B ; Ausavarungnirun, R ; Mutlu, O ; Sharif University of Technology
Association for Computing Machinery
2018
Abstract
Graphics Processing Units (GPUs) employ large register files to accommodate all active threads and accelerate context switching. Unfortunately, register files are a scalability bottleneck for future GPUs due to long access latency, high power consumption, and large silicon area provisioning. Prior work proposes hierarchical register file, to reduce the register file power consumption by caching registers in a smaller register file cache. Unfortunately, this approach does not improve register access latency due to the low hit rate in the register file cache. In this paper, we propose the Latency-Tolerant Register File (LTRF) architecture to achieve low latency in a two-level hierarchical...
Visibility of a moving segment
, Article Proceedings of the 2009 International Conference on Computational Science and Its Applications, ICCSA 2009, 29 June 2009 through 2 July 2009, Yongin ; 2009 , Pages 169-176 ; 9780769537016 (ISBN) ; Ghodsi, M ; Sharif University of Technology
2009
Abstract
In this paper we define topological segment visibility, and show how to compute and maintain it as the observer moves in the plane. There are n non-intersecting line segment objects in the plane, and we have a segment observer among them. As the topological visibility of a line segment has not been studied before, we first consider static case of the problem, in which the observer and objects are static, and then we study dynamic case of the problem, in which the observer can move among obstacles
Three-dimensional simulation of hydrodynamics in a rotating disc contactor using computational fluid dynamics
, Article Chemical Engineering and Technology ; Volume 32, Issue 1 , 2009 , Pages 93-102 ; 09307516 (ISSN) ; Hedayat, N ; Ziyari, A ; Kazemzadeh, M ; Shafiee, M ; Sharif University of Technology
2009
Abstract
The 3D simulation of the hydrodynamic behavior of a rotating disc contactor (RDC) by means of computational fluid dynamics (CFD) was investigated for the n-butanol-succinic acid-water (BSW) system. For the two-phase liquid-liquid flow, the velocity distribution of the continuous phase and drop size distributions were determined using the k-ω turbulence model in conjunction with the Eulerian-Eulerian approach and MUSIG model. In this system in which the holdup of the dispersed phase is low, the continuous phase velocity was computed by simultaneously solving the Navier-Stokes equations beside the different models of turbulence. The motions of the dispersed phase was calculated while...
Polynomial datapath optimization using partitioning and compensation heuristics
, Article Proceedings - Design Automation Conference, 26 July 2009 through 31 July 2009, San Francisco, CA ; 2009 , Pages 931-936 ; 0738100X (ISSN); 9781605584973 (ISBN) ; Alizadeh, B ; Fujita, M ; Sharif University of Technology
2009
Abstract
Datapath designs that perform polynomial computations over Z 2n are used in many applications such as computer graphics and digital signal processing domains. As the market of such applications continues to grow, improvements in high-level synthesis and optimization techniques for multivariate polynomials have become really challenging. This paper presents an efficient algorithm for optimizing the implementation of a multivariate polynomial over Z2n in terms of the number of multipliers and adders. This approach makes use of promising heuristics to extract more complex common sub-expressions from the polynomial compared to the conventional methods. The proposed algorithm also utilizes a...
Qualitative study of nanocluster positioning process: 2D molecular dynamics simulations
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 13, Issue PART B , 2009 , Pages 1161-1170 ; 9780791848746 (ISBN) ; Meghdari, A ; Jalili, N ; Amiri, F ; Sharif University of Technology
2009
Abstract
One of the key factors in the assembly of nanoclusters is the precise positioning of them by a manipulation system. Currently the size of clusters used as building blocks is shrinking down to a few nanometers. In such cases, the particle nature of matter plays an important role in the manipulator/cluster/substrate interactions. Having a deeper insight to the aforementioned nanoscale interactions is crucial for prediction and understanding of the behavior of nanoclusters during the positioning process. In the present research, 2D molecular dynamics simulations have been used to investigate such behaviors. Performing planar simulations can provide a fairly acceptable qualitative tool for our...
Digital video watermarking in 3-D ridgelet domain
, Article 11th International Conference on Advanced Communication Technology, ICACT 2009, Phoenix Park, 15 February 2009 through 18 February 2009 ; Volume 3 , 2009 , Pages 1643-1646 ; 17389445 (ISSN); 9788955191387 (ISBN) ; Ghaemmaghami, S ; Omidyeganeh, M ; IEEE Communications Society, IEEE ComSoc ; Sharif University of Technology
2009
Abstract
A new method for digital video watermarking is presented in this paper. For data embedding we use 3-D ridgelet domain introduced by Helbert. The redundancy of this transform is substantial, so extraction of the hidden data is impossible in this domain. To overcome this problem, we introduce a modified ridgelet transform with little redundancy, and embed watermark in this domain. Experimental results show that this scheme is robust against collusion attack, frame cropping, frame swapping, frame dropping, noise attack and the MJPEG (Motion JPEG) compression
A new computational algorithm for 3D contact modeling of large plastic deformation in powder forming processes
, Article Computational Materials Science ; Volume 46, Issue 1 , 2009 , Pages 203-220 ; 09270256 (ISSN) ; Biabanaki, S. O. R ; Vafa, A. R ; Taheri Mousavi, S. M ; Sharif University of Technology
2009
Abstract
In this paper, the three-dimensional large deformation frictional contact of powder forming process is modeled using a simple computational algorithm based on the augmented-Lagrange approach. The technique is applied by imposing the contact constraints and modifying the contact properties of frictional slip through the node-to-surface (NTS) contact algorithm. The Coulomb friction law is employed to simulate the friction between the rigid punch and the work-piece by the use of penalty and augmented-Lagrange approaches. It is shown that the augmented-Lagrange technique significantly improves imposing of the constraints on contact surfaces. The nonlinear contact friction algorithm is employed...
A Fast Algorithm for Shadow Generation with Low Distortion Based on Shadow Map Technique
, M.Sc. Thesis Sharif University of Technology ; Jamzad, Mansour (Supervisor)
Abstract
Shadows are one of the most important details in graphical images. There exist many shadow generation algorithms each of which suffers from some problems. High processing time and ill-shaped shadow borders, known as alasing, are some of such problems. In this paper, we propose a heuristic method based on standard shadow map technique, named rotated shadow maps, to generate excellent hard shadows. Our method uses some shadow maps which are generated from the same view but objects are slightly rotated around the center of view area. Rotated shadow maps can be considered as an independent hard shadow generation algorithm. Also it can be combined with other shadow map based approaches. Utilizing...
Proposal of winding function model for geometrical optimization of linear sinusoidal area resolvers
, Article IEEE Sensors Journal ; Volume 19, Issue 14 , 2019 , Pages 5506-5513 ; 1530437X (ISSN) ; Alipour Sarabsi, R ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper proposes an analytical model based on winding function method for analysis of linear sinusoidal area resolver. The accuracy of the proposed model is verified using 3-D time variant finite element analysis and then an optimization based on genetic algorithm is employed for performance improvement of the sensor. Afterwards, the influence of longitudinal end effect on the position error of the studied sensor is investigated and a proper compensating method is presented. Finally, the optimal, compensated sensor is built for experimental measurements. Close agreement between the simulation and the measured position verified the design, analysis, and optimization process. © 2001-2012...
Coordinated DVFS and Precision Control for Deep Neural Networks
, Article IEEE Computer Architecture Letters ; Volume 18, Issue 2 , 2019 , Pages 136-140 ; 15566056 (ISSN) ; Hafez Kolahi, H ; Reda, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Traditionally, DVFS has been the main mechanism to trade-off performance and power. We observe that Deep Neural Network (DNN) applications offer the possibility to trade-off performance, power, and accuracy using both DVFS and numerical precision levels. Our proposed approach, Power-Inference accuracy Trading (PIT), monitors the server's load, and accordingly adjusts the precision of the DNN model and the DVFS setting of GPU to trade-off the accuracy and power consumption with response time. At high loads and tight request arrivals, PIT leverages INT8-precision instructions of GPU to dynamically change the precision of deployed DNN models and boosts GPU frequency to execute the requests...