Sharif Digital Repository

This paper presents a robust tracking approach to handle challenges such as occlusion and appearance change. Here, the target is partitioned into a number of patches. Then, the appearance of each patch is modeled using a dictionary composed of corresponding target patches in previous frames. In each frame, the target is found among a set of candidates generated by a particle filter, via a likelihood measure that is shown to be proportional to the sum of patch-reconstruction errors of each candidate. Since the target's appearance often changes slowly in a video sequence, it is assumed that the target in the current frame and the best candidates of a small number of previous frames, belong to... 

Mel-frequency Cepstral coefficients are widely used for feature extraction in speech recognition systems. These features use Mel-scaled filters. A new filter-bank based on dependencies between frequency components and phoneme characteristics is proposed. F-ratio and mutual information are used for this purpose. A new filter-bank is designed in which frequency resolution of sub-band filters is inversely proportional to the computed dependency values. These new filterbank is used instead of Mel-scaled filters for feature extraction. A phoneme recognition experiment on FARSDAT Persian language database showed that features extracted using the proposed filter-bank reach higher accuracy (63.92%)... 

This paper presents a structured dictionary-based model for hyperspectral data that incorporates both spectral and contextual characteristics of spectral samples. The idea is to partition the pixels of a hyperspectral image into a number of spatial neighborhoods called contextual groups and to model the pixels inside a group as members of a common subspace. That is, each pixel is represented using a linear combination of a few dictionary elements learned from the data, but since pixels inside a contextual group are often made up of the same materials, their linear combinations are constrained to use common elements from the dictionary. To this end, dictionary learning is carried out with a... 

In this letter, a spatially weighted sparse unmixing approach is proposed as a front-end for hyperspectral image classification using a linear SVM. The idea is to partition the pixels of a hyperspectral image into a number of disjoint spatial neighborhoods. Since neighboring pixels are often composed of similar materials, their sparse codes are encouraged to have similar sparsity patterns. This is accomplished by means of a reweighted ℓ1 framework where it is assumed that fractional abundances of neighboring pixels are distributed according to a common Laplacian Scale Mixture (LSM) prior with a shared scale parameter. This shared parameter determines which endmembers contribute to the group... 

Semisupervised hyperspectral unmixing finds the ratio of spectral library members in the mixture of hyperspectral pixels to find the proportion of pure materials in a natural scene. The two main challenges are noise in observed spectral vectors and high mutual coherence of spectral libraries. To tackle these challenges, we propose a probabilistic sparse regression method for linear hyperspectral unmixing, which utilizes the implicit relations of neighboring pixels. We partition the hyperspectral image into rectangular patches. The sparse coefficients of pixels in each patch are assumed to be generated from a Laplacian scale mixture model with the same latent variables. These latent variables... 

Classifying streams of data, for instance financial transactions or emails, is an essential element in applications such as online advertising and spam or fraud detection. The data stream is often large or even unbounded; furthermore, the stream is in many instances non-stationary. Therefore, an adaptive approach is required that can manage concept drift in an online fashion. This paper presents a probabilistic non-parametric generative model for stream classification that can handle concept drift efficiently and adjust its complexity over time. Unlike recent methods, the proposed model handles concept drift by adapting data-concept association without unnecessary i.i.d. assumption among the... 

Monitoring large-scale networks is a critical yet challenging task. Enormous number of nodes and links, limited power, and lack of direct access to the entire network are the most important difficulties. In applications such as network routing, where all nodes need to monitor the status of the entire network, the situation is even worse. In this letter, a collaborative model in which nodes pick up information from measurements generated by other nodes is proposed. Using this model, for the first time, an upper bound is derived for the number of measurements that each node must generate, such that the expected number of measurements observed by each node is sufficient to provide a global view... 

Functional behavior of the brain can be captured using functional Magnetic Resonance Imaging (fMRI). Even though fMRI signals have temporal and spatial structures, most studies have neglected the temporal structure when inferring mental states (brain decoding). This has two main side effects: 1. Degradation in brain decoding performance due to lack of temporal information in the model, 2. Inability to provide temporal interpretability. Few studies have targeted this issue but have had less success due to the burdening challenges related to high feature-to-instance ratio. In this study, a novel model for incorporating temporal information while maintaining a low feature-to-instance ratio, is... 

The prediction of rock sawability is very important in the cost estimation and the best planning of the plants. Rock sawability depends on the machine characteristics and rock mechanical properties. In this study, a new classification was developed with the respect to rock mechanical properties such as Uniaxial Compressive Strength, Brazilian tensile strength, Schmidt hammer value and Los Angeles abrasion loss. Using this system the carbonate rock sawability index (CRSi) of several types of carbonate rock was evaluated and classifi ed into fi ve categories and then a new model was developed with the respect to CRSi and machining characteristics by using the statistical analyses for... 

Semi-Supervised Learning (SSL) has become a topic of recent research that effectively addresses the problem of limited labeled data. Many SSL methods have been developed based on the manifold assumption, among them, the Local and Global Consistency (LGC) is a popular method. The problem with most of these algorithms, and in particular with LGC, is the fact that their naive implementations do not scale well to the size of data. Time and memory limitations are the major problems faced in large-scale problems. In this paper, we provide theoretical bounds on gradient descent, and to overcome the aforementioned problems, a new approximate Newton's method is proposed. Moreover, convergence... 

In this study, novel graphene oxide/chitosan nanocomposite coatings with long term drugeluting potential are presented. The coatings are fabricated by the facile and reproducible electrophoretic deposition technique. Analysis of the prepared films shows that the graphene oxide nanosheets are exfoliated in the chitosan matrix. Fourier-transform infrared spectrometry reveals polymer attachment to the carboxylic bonds of graphene oxide, providing a strong interaction and exfoliation of the nanolayers. In vitro viability assay by human osteosarcoma cells (MG-63) demonstrates that the nanocomposite films are highly biocompatible up to 30 wt% graphene oxide, but at higher concentrations a slight... 

Magnesium oxide nanoparticles (MgO NPs) have emerged as potential materials for various biomedical applications due to their unique physicochemical properties, including biodegradability, biocompatibility, cationic capacity, high stability and redox properties. MgO NPs have become an attractive platform to combat microbes and may be a promising alternative to overcome challenges associated with eliminating microbial biofilms and antibiotic resistance. Hence, due to the increasing use of MgO NPs in biomedicine, new synthetic strategies for MgO NPs are necessary. MgO NPs synthesised using green methods are non-toxic, eco-friendly and have high stability for a wide range of biological, medical... 

An extensive experimental test to study the flow behavior over a rectangular wing in the subsonic wind tunnel in Iran was conducted. The tests included, surface pressure measurements at three locations and wake study at different angles of attack and free-stream Reynolds number. Further, to investigate the sidewall effects on the model pressure and wake, suction were applied at the wing root, where the model was attached to the tunnel wall. Suction affected surface pressure at all three locations by increasing the model pressure peak, preventing separation near the T. E., etc. at low angles of attack. However at moderate to high angles of attack, suction affected only the root pressure... 

Extensive experiments were conducted to study the effect of various parameters on the surface pressure distribution and transition point of an aerofoil section used in a wind turbine blade. In this paper details of the variation of transition point on the aforementioned aerofoil are presented. The aerofoil spanned the wind-tunnel test section and was oscillated sinusoidally in pitch about the quarter chord. The imposed variables of the experiments were free stream velocity, amplitude of motion, mean angle-of-attack, and oscillation frequency. The spatial-temporal progressions of the leading-edge transition point and the state of the unsteady boundary-layer were measured using eight... 

Wing rock motion can be described as an oscillatory bank angle buildup to a constant amplitude rocking motion. This phenomenon is realized for delta wings with more than 74 degrees leading edge sweep angles, where asymmetric vortex shedding occurs before vortex breakdown. For wings with sweep angles less than 74 degrees, rocking motion occurs if the wing is in a yawed situation. In this paper, a new and simple method has been presented to predict the amplitude and frequency of oscillation of delta wings undergoing rocking motion at high angles of attack. The predicted data are in excellent agreement with those obtained by experimental studies for wings with sweep angles of 76 and 80 degrees  

Cost-effective and reliable damage detection is critical for utilization of composite materials. This paper utilizes PZT piezoelectric disks to excite the first symmetric Lamb wave (S0 mode). The interaction of Lamb wave mode with a through-thickness crack of different lengths and angles in [0/45/-45/90]s CF/EP laminate plates is analyzed in terms of finite element method. This study contributes to the damage detection by developing an improved wavelet-based signal processing technique that enhances the visibility and interpretation of the Lamb wave signals related to defects. Based on the amount of energy dissipated by the damage, a damage index is defined as the function of an electric... 

Reinforced concrete slabs are common structural elements that could be exposed to impact loading. Although use of reinforced concrete slabs and utilization of Fiber Reinforced Polymer (FRP) as alternative to traditional steel reinforcement slabs are growing, but the influence of various parameters on their response under impact loads is not properly evaluated. This study investigated the effect of rebar's material, amount and arrangement of reinforcements, concrete strength and slab thickness on dynamic behavior of reinforced concrete slabs using both laboratory experiments and numerical simulations. Performance of fifteen 1000 × 1000 mm concrete slabs, including two 75 mm thick plain slabs,... 

Recently, to improve the dynamic behavior of Reinforced Concrete (RC) slabs under impact load, the methods of externally bonding Glass Fiber Reinforced Polymer (GFRP) sheets to slab and internally reinforcing concrete by steel fibers have been proposed. Nevertheless, it is required to investigate the comparison between these two methods on response of RC slabs under impact loads. In this study, the influence of volume fraction of steel fibers, the number of GFRP sheet layers (one or two) and the arrangement of GFRP sheets (covering the whole or parts of surface), are examined. Performance of fourteen 1000 × 1000 × 75 mm concrete slabs including one plain slab, one steel RC slab, three steel...