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A modified patch propagation-based image inpainting using patch sparsity
, Article AISP 2012 - 16th CSI International Symposium on Artificial Intelligence and Signal Processing ; 2012 , Pages 43-48 ; 9781467314794 (ISBN) ; Mahdavi-Amiri, N ; Sharif University of Technology
2012
Abstract
We present a modified examplar-based inpainting method in the framework of patch sparsity. In the examplar-based algorithms, the unknown blocks of target region are inpainted by the most similar blocks extracted from the source region, with the available information. Defining a priority term to decide the filling order of missing pixels ensures the connectivity of object boundaries. In the exemplar-based patch sparsity approaches, a sparse representation of missing pixels was considered to define a new priority term. Here, we modify this representation of the priority term and take measures to compute the similarities between fill-front and candidate patches. Comparative reconstructed test...
An Effective Power Gating Method for NoC through Idle Time Management
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
With the advent in technology and shrinking the transistor size down to nano scale, static power may become the dominant power component in Networks-on-Chip (NoCs). Power-gating is an efficient technique to reduce the static power of under-utilized resources in different types of circuits. For NoC, routers are promising candidates for power gating, since they present high idle time. However, routers in a NoC are not usually idle for long consecutive cycles due to distribution of resources in NoC and its communication-based nature, even in low network utilizations. Therefore, power-gating loses its efficiency due to performance and power overheads of the packets that encounter powered-off...
Effect of alumina nanoparticles on hot strength and deformation behaviour of Al-5vol% Al 2O 3 nanocomposite: Experimental study and modelling
, Article Journal of Nanoscience and Nanotechnology ; Volume 10, Issue 4 , 2010 , Pages 2641-2645 ; 15334880 (ISSN) ; Sanjari, M ; Simchi, A ; Seyed Reihani, S. M ; Simancik, F ; Sharif University of Technology
2010
Abstract
Hot deformation behaviour of as-extruded Al-5vol% Al 2O 3 nanocomposite was investigated at temperatures range 350 to 450°C and initial strain rates of 5.5 × 10 -4 to 10 -1 s -1 and compared with those of monolithic (unreinforced) aluminium. Both extruded materials exhibited work-softening during hot deformation. The results showed that with the addition of 5 vol% alumina nanoparticles with an average particle size of 35 nm, a significant increase in compressive strength of aluminium was obtained. For instance, at 350°C an abrupt rise of ∼340% in hot strength of the nanocomposite relative to monolithic aluminium was achieved. TEM investigation of microstructure of the nanocomposite after hot...
Design of a Scalable Optical Network-on-Chip by Reducing Role of Electrical Transactions
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
As the number of processing cores on a single chip continues to grow, the need for a high bandwidth, low power communication structure, will be the most important requirement of the next generation chip multiprocessors. Today, a major part of power consumption in multicore architectures belongs to interconnects. Due to these facts, reducing power consumption, as well as supporting high performance, is of major concern in these architectures. Optical interconnects have the potential to replace electrical wires to solve the bottleneck of communications in integrated circuits. Various routers and architectures with different points of view, have been recently designed considering existing...
Accelerated FPGA-Based NOC Simulation With Software Configuration
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
ITRS shows next generation of Multiprocessor System on Chip (MPSoCs) designs will contain hundreds of heterogeneous cores, running at different speeds and voltage levels. Networks-On-Chip (NoC) provide a structured way of realizing interconnections on silicon, and obviate the limitations of bus-based solution. As the number of components in MPSoCs increases, the interconnect schemes based on NoC approach are increasingly used. However, NoC designs have many power, area, and performance trade-offs in topology, buffer sizes, routing algorithms and flow control mechanisms, hence the study of new NoC designs can be very time-intensive.
To address these challenges, we propose a new...
To address these challenges, we propose a new...
An All-Optical NoC with Multicasting Capability
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
The importance of power consumption in high performance multiprocessors, combined with power reduction capability of on-chip optical interconnects, offers optical network-on-chip (ONoC) as a new technology solution which can deliver considerably higher bandwidth and lower latencies with significantly lower power dissipation than an interconnection network based only on electronic signaling. An on-chip network should be able to support multicast communications efficiently whether it is an optical or electrical network. On the other hand, multicast communications in optical networks-on-chip has been implemented using shared bus which is not scalable. Moreover, most of optical on-chip...
Evaluating Energy Efficiency and Scalability of Timing Channel- protection Techniques exploited Exploited for Single Chip Cloud Computer
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
Although cloud porcessors have lots of benefits, they have brought new challenges for designers; one of these issues, is information leakage through Timing Channel Attack in shared hardware resources. Among these shared resources, main memory controller is less understood. Also applying timing channel protection technquies to shared memory controller, in comparison with other parts such as NoC, caches, etc, can impose high performance overhead to system throughput. Temporal Partitioning (TP) is the baseline secure scheduling algorithm that was proposed for cope with timing channel attack in shared memory controller; but beside this protection, TP compels high performance degradation. In this...
Data Sharing Aware Scheduling for Reducing Memory Accesses in GPGPUs
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
Access to global memory is one of the bottlenecks in performance and energy in GPUs. Graphical processors uses multi-thread in streaming multiprocessors to reduce memory access latency. However, due to the high number of concurrent memory requests, the memory bandwidth of low level memorties and the interconnection network are quickly saturated. Recent research suggests that adjacent thread blocks share a significant amount of data blocks. If the adjacent thread blocks are assigned to specific streaming multiprocessor, shared data block can be rused by these thread blocks. However the thread block scheduler assigns adjacent thread blocks to different streaming multiprocessors that increase...
Proposal af a New Approach to Improve Communication and Computation Efficiency of Federated Edge Learning with Heterogeneous Resources
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
In practice, to implement Federated learning on edge networks, devices must repeatedly transmit their trained models to the edge server through wireless links to update the global model; Due to the heterogeneity in the Federated Edge learning system, such as lack of power, some devices may not be able to connect to the base station and reduce the performance of the trained model or, if connected, impose a large delay on the learning process. To overcome the mentioned challenge, we propose a Collaborative Federated learning framework. In this framework, some devices can participate in Federated learning without connecting to the base station; In this way, devices that are not able to...
Mechanical properties of Al-Al2O3 nanocomposite produced by mechanical milling and powder hot extrusion
, Article European Powder Metallurgy Congress and Exhibition, Euro PM 2007, Toulouse, 15 October 2007 through 17 October 2007 ; Volume 2 , 2007 , Pages 259-264 ; 9781899072293 (ISBN) ; Simchi, A ; Seyed Reihani, S. M ; Simancik, F ; Balog, M ; Csuba, A ; Sharif University of Technology
European Powder Metallurgy Association (EPMA)
2007
Abstract
In the present work, ultrafine-grained Al-5vol.% Al2O3 nanocomposite was synthesized through mechanical milling followed by direct powder extrusion method. The characteristics of the processed nanocomposite were examined by electron microscopy (SEM and TEM), Xray diffraction (XRD), tensile test and Vickers hardness measurement. It was shown that the addition of the reinforcement nanoparticles accelerates the milling process of the aluminum matrix and enhances the grain refinement of the aluminum matrix. An improved mechanical strength as compared with Al-Al2O3 microcompoiste was obtained. A dimple-type fracture mode was observed, which is a clear evidence of micro-deformation. In addition,...
A Communication Model between SIMT Cores for Improving GPU Performance
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
In recent years, GPUs are becoming an ideal candidate for processing a variety of high performance applications. By relying on thousands concurrent threads in applications and the computational power of large numbers of computing units; GPGPUs have provided high performance and throughput. To achieve the potential computational power of GPGPUs in broader kinds of applications, we need to apply some modifications in their architecture. In the baseline architecture, the maximum part of chip area is devoted to SIMT cores which their communication is handled through an interconnection network and a slow off-chip memory. Recent research shows that out of many types of miss events the last level...
Structure and texture image inpainting
, Article Proceedings of the 2010 International Conference on Signal and Image Processing, ICSIP 2010, 15 December 2010 through 17 December 2010 ; 2010 , Pages 119-124 ; 9781424485949 (ISBN) ; Jamzad, M ; Mahdavi Amiri, N ; Sharif University of Technology
2010
Abstract
Inpainting refers to the task of filling in the missing or damaged regions of an image in an undetectable manner. We have an image to be reconstructed in a user-defined region. We use a fast decomposition method to obtain two components of the image, namely structure and texture. Reconstruction of each component is performed separately. The missing information in the structure component is reconstructed using a structure inpainting algorithm, while the texture component is repaired by a texture synthesis technique. To obtain the inpainted image, the two reconstructed components are composed together. Taking advantage of both the structure inpainting methods and texture synthesis techniques,...
Heat Conduction Modeling in Optical Network-on-Chips and Presenting Thermally-Resilient ONoC Architecture
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor) ; Kouhi, Somayyeh (Co-Advisor)
Abstract
Integrated silicon photonic networks have attracted a lot of attention in the recent decade due to their potential for low-power and high-bandwidth communications. However, despite high bandwidth and low-loss data communication capability, optical NoCs are susceptible to on-chip temperature variations. In these promising networks, packets’ erroneous routing due to thermally-induced resonant wavelength shift of microring resonators are common temporary faults unless heat control mechanism is adopted. In other words, thermal drifts may paralyze wavelength-based operation of these networks. On the other hand, employing a heat control mechanism in an ONoC necessitates developing thermal fault...
Modeling and active control of chatter vibrations of piezoelectric stacked machining arm in micro-turning process
, Article Meccanica ; Volume 55, Issue 9 , 18 July , 2020 , Pages 1707-1731 ; Moradi, H ; Movahhedy, M. R ; Sharif University of Technology
Springer
2020
Abstract
Self-excited vibrations known as chatter are considered as the most detrimental issue in micro-turning processes. Occurring unpredictably, they adversely affect the tool life, productivity rate and surface quality of the machining processes. In this paper, a novel machining arm is modeled as a piezoelectric stacked rod which is subjected to a chatter force in the orthogonal micro-turning process. Due to the fact that machining processes are affected by various sources of uncertainties, H∞ robust control approach is used to suppress the chatter vibrations of the machining arm in the presence of tool wear and dynamic model parameter variations. Also, input control force of the system is...
An investigation on the compressibility of aluminum/nano-alumina composite powder prepared by blending and mechanical milling
, Article Materials Science and Engineering A ; Volume 454-455 , 2007 , Pages 89-98 ; 09215093 (ISSN) ; Hafizpour, H. R ; Simchi, A ; Sharif University of Technology
2007
Abstract
The densification response of aluminum powder reinforced with 5 vol.% nanometric alumina particles (35 nm) during uniaxial compaction in a rigid die was studied. The composite powder was prepared by blending and mechanical milling procedures. To determine the effect of the reinforcement nanoparticles on the compressibility of aluminum powder, monolithic Al powder, i.e. without the addition of alumina, was also examined. It was shown that at the early stage of compaction when the rearrangement of particles is the dominant mechanism of the densification, disintegration of the nanoparticle clusters and agglomerates under the applied load contributes in the densification of the composite powder...
Structural changes during synthesizing of nanostructured W-20 wt% Cu composite powder by mechanical alloying
, Article Materials Science and Engineering A ; Volume 445-446 , 2007 , Pages 86-93 ; 09215093 (ISSN) ; Simchi, A ; Razavi Hesabi, Z ; Sharif University of Technology
2007
Abstract
Nanostructured W-20 wt% Cu composite powder was synthesized by mechanical alloying (MA) in an Attritor ball mill. The morphological changes and structural evolution of the composite powder during MA was studied by employing scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), laser particle size analyzer (LPS), inductively coupled plasma (ICP) spectrometry, atomic absorption spectrophotometery (AAS), and the bulk powder density measurement. The results were compared with those obtained from attrition milling of monolithic W and Cu powders processed at the same condition. Whereas the milling mechanism of the monolithic powders follow the ductile (for Cu)...
Hydroxyapatite nanocomposites: Synthesis, sintering and mechanical properties
, Article Ceramics International ; Volume 39, Issue 3 , April , 2013 , Pages 2197-2206 ; 02728842 (ISSN) ; Eskandari, A ; Baroonian, M. H ; Berenov, A ; Razavi Hesabi, Z ; Taheri, M ; Sadrnezhaad, S. K ; Sharif University of Technology
2013
Abstract
Two different hydroxyapatite based composites reinforced by oxide ceramic (20 wt%) nano crystals were synthesized by high-energy ball milling and sintered by pressure less technique. Alumina and titania nanoparticles as secondary phases improved densification and mechanical behavior of apatite and postponed its decomposition to the tricalcium phosphate (TCP) phases at elevated temperatures. Increasing the relative density of apatite using nano reinforcements leads to enhance the bending strength by more than 40% and 27% (as compared to the pure HA) and increase the hardness from 2.52 to 5.12 (Al2O3 composite) and 4.21 (TiO2 addition) GPa, respectively. Transmission electron microscopy (TEM),...
Conditional Access System Design for DVB-T Receiver
,
M.Sc. Thesis
Sharif University of Technology
;
Hesabi, Shaahin
(Supervisor)
;
Sharifkhani, Mohammad
(Supervisor)
Abstract
In the Pay-TV industry, it is necessary to limit access of unauthorized users. Conditional Access System (CAS) is the solution. In the Pay-TV, the ability of instant join and leave operation is desirable for users. On the other hand, this characteristic is in contradiction with growth of user number.
Previous proposed conditional access systems address the requirement of pay-TV from several aspects. Key distribution management is on of them which plays a key role in the security and efficiency of a conditional access system. Re-examining the process of key distribution management make it possible to find a way to provide a greater flexibility for the users.
The purpose of this...
Previous proposed conditional access systems address the requirement of pay-TV from several aspects. Key distribution management is on of them which plays a key role in the security and efficiency of a conditional access system. Re-examining the process of key distribution management make it possible to find a way to provide a greater flexibility for the users.
The purpose of this...
Vortex-Induced Vibrations of Free Spanning Pipelines
, M.Sc. Thesis Sharif University of Technology ; Ghoreishi, Reza (Supervisor) ; Abbaspour, Majid (Supervisor)
Abstract
When a submarine pipeline is laid, pipeline spans may exist due to the unevenness of the seabed. Such pipeline spans when exposed to currents, may undergo vortex-induced vibration (VIV). As the flow velocity increases, the cross-flow oscillation begins to occur and vortex shedding frequency may approach the natural frequency of the pipe span. Amplified response due to resonance between the vortex shedding frequency of the free span may cause fatigue damage. Thus, the determination of the critical allowable span length under the various environments becomes the most challenging areas in the offshore industry. A substantial research effort related to various aspects of VIV and free span...
Modeling fatigue behavior of quasi-isotropic laminates
, Article Procedia Engineering, 5 June 2011 through 9 June 2011 ; Volume 10 , June , 2011 , Pages 3764-3768 ; 18777058 (ISSN) ; Kouchi, A ; Tadi Beni, Y ; Abadyan, M ; Sharif University of Technology
2011
Abstract
Fatigue behavior of quasi-isotropic carbon/epoxy laminates were studied, using six stacking sequences. Experimental results show that there is a significant stacking sequence effect on monotonic and cyclic performance of laminates. Though by changing the stacking sequence the difference between failure strength of the strongest and weakest lay-ups reaches only to ∼ 12 %, the difference between fatigue lives (cycles to failure) increased ∼ 1000% in some loading regions. In addition, both linear and sigmoidal functions were examined to model the fatigue life behavior