Sharif Digital Repository

One of the efficient solar energy harvesting technics is the parabolic trough concentrated solar power plant. However, if the concentrated solar power plant were not equipped with a storage system, the power plant capacity factor would be deficient. Latent thermal energy storage system using phase change material (PCM) is a high energy density storage system to provide durable energy with a constant temperature. In this study, first, a dynamic analysis is performed implementing TRNSYS software on the parabolic trough concentrated solar power plant located in Shiraz, Iran. Consequently, this system is assisted by the latent thermal energy storage system to improve its performance and capacity... 

In this paper, we introduce a technique for improving power distribution characteristics of space time block codes (STBCs) which include peak to average power ratio (PAPR), average to minimum power ratio (Ave/min), and probability of transmitting “zero” by antenna. We consider STBCs in multiple input multiple output (MIMO) and multiple input single output (MISO) systems that achieve full diversity for linear or maximum likelihood (ML) receivers. It is proved that by multiplying a specific non-singular square matrix by the code matrix, a new code is obtained that achieves full diversity and the power distribution characteristics are improved. The proposed technique is general can be applied... 

In this paper, an iterative signal reconstruction method is extended to cancel multi-user clipping noise in a uplink MC-CDMA systems. Clipping is the simplest method to overcome high peak-to-average power ratio of multi-carrier signals but it makes the multi-carrier signals distorted. Reconstruction methods use non-distorted samples to reconstruct distorted samples in the receiver but multi-user interference causes the methods do not work properly because all the received samples are distorted by clipping and interference and so there is no undistorted samples to be used in recovering clipped samples. On the other hand, multi-user interference cancellation methods do not work properly... 

In spite of the extensive literature on the analysis of the muscle synergies during gait, the functionality of these synergies has not been studied in detail. This study explored the relationship between the motor modules and the kinematic maneuvers involved in human walking. Motion and surface electromyography data (of 28 trunk and lower extremity muscles) were acquired from ten healthy subjects during ten trials of self-selected speed gait each. The joint angle trajectories were half-wave rectified and divided into two independent positive directional degrees-of-freedom. The muscle and kinematic synergies were both extracted using the non-negative matrix factorization (NNMF) technique and... 

In this paper, an iterative method is proposed to jointly cancel multi-user interference and clipping noise in uplink Multi-Carrier Code Division Multiple Access (MC-CDMA) systems. Clipping is the simplest method to overcome high peak-to-average power ratio of multi-carrier signals but it makes the signals distorted. Reconstruction methods use non-distorted samples to reconstruct distorted samples in the receiver but multi-user interference causes the methods do not work properly because all the received samples are distorted due to clipping and interference and so there is no undistorted samples to be used in recovering clipped samples. On the other hand, multi-user interference... 

Techniques available in graph theory can be applied to signals recorded from human brain. In network analysis of EEG signals, the individual nodes are EEG sensor locations and the edges correspond to functional relations between them that are extracted from EEG time series. In this paper, we study EEG-based directed functional networks in Alzheimer's disease (AD). To this end, directed connectivity matrices of 25 AD patients and 26 healthy subjects are processed and a number of meaningful graph theory metrics are studied. Our data show that functional networks of AD brains have significantly reduced global connectivity in alpha and beta bands (P < 0.05). The AD brains have significantly... 

Background: Accurate tracking of the heart surface motion is a major requirement for robot assisted beating heart surgery. Method: The feasibility of a stereo infrared tracking system for measuring the free beating heart motion was investigated by experiments on a heart motion simulator, as well as model surgery on a dog. Results: Simulator experiments revealed a high tracking accuracy (81 μm root mean square error) when the capturing times were synchronized and the tracker pointed at the target from a 100 cm distance. The animal experiment revealed the applicability of the infrared tracker with passive markers in practical heart surgery conditions. Conclusion: With the current technology,... 

In this study, a novel artificial intelligence-based approach is presented to directly estimate the surface topography. To this aim, performance of different artificial intelligence-based techniques, including the multi-layer perceptron neural, radial basis function neural, and adaptive neural fuzzy inference system networks, in estimation of the sample topography is investigated. The results demonstrate that among the designed observers, the multi-layer perceptron method can estimate surface characteristics with higher accuracy than the other methods. In the classical imaging techniques, the scanning speed of atomic force microscope is restricted due to the time required by the oscillating... 

Conductive self -electrical stimuli bioactive scaffolds could be used the potential for peripheral nerve regeneration with the maximum efficiency. To produce such conductive self-electrical stimuli bioactive scaffolds, chopped spun piezoelectric nanofibers of polyvinylidene fluoride/mesoporous silica nanoparticle (PVDF/MCM41) are prepared and incorporated in gellan/polyaniline/graphene (gellan/PAG) nanocomposites which have been previously prepared by incorporation of polyaniline/graphene (PAG) nanoparticles in gellan gel at 80 °C. Highly conductive binary doped polyaniline/graphene nanoparticles are prepared by chemical oxidative polymerization of aniline monomer using in-suite... 

The ability to speak lucidly plays a key role in social relations. Consequently, the role of the larynx is quite important, and timely diagnosis of laryngeal diseases has proved to be crucial. In this study, a simple computational model for inverse of speech production model is employed to extract the glottal waveform using speech signal. This waveform has useful information about vocal folds performance in terms of providing evidence for distinguishing pathological disorders. Furthermore, obtaining the significance of classification results is important, because it leads to reliable inferences. This study utilizes the sustained vowel sound /a/ and a well-referenced database, namely MEEI. In... 

The current study was designed to assess the association between temporal variations in urban PM2.5 chemical composition, sources, and the oxidative stress and inflammatory response in an alveolar macrophage (AM) model. A year-long sampling campaign collected PM2.5 samples at the Sharif University in Tehran, Iran. PM-induced reactive oxygen species (ROS) production was measured both with an acellular dithiothreitol consumption assay (DTT-ROS; ranged from 2.1 to 9.3 nmoles min−1 m−3) and an in vitro macrophage-mediated ROS production assay (AM-ROS; ranged from 125 to 1213 μg Zymosan equivalents m−3). The production of tumor necrosis factor alpha (TNF-α; ranged from ~60 to 518 pg TNF-α m−3)...