Sharif Digital Repository

In this paper, we propose a novel method for extracting fiducial points (FPs) of the beats in electrocardiogram (ECG) signals using switching Kalman filter (SKF). In this method, according to McSharry's model, ECG waveforms (P-wave, QRS complex and T-wave) are modeled with Gaussian functions and ECG baselines are modeled with first order auto regressive models. In the proposed method, a discrete state variable called “switch” is considered that affects only the observation equations. We denote a mode as a specific observation equation and switch changes between 7 modes and corresponds to different segments of an ECG beat. At each time instant, the probability of each mode is calculated and... 

Apnea bradycardia (AB) is an outcome of apnea occurrence in preterm infants and is an observable phenomenon in cardiovascular signals. Early detection of apnea in infants under monitoring is a critical challenge for the early intervention of nurses. In this paper, we introduce two switching Kalman filter (SKF) based methods for AB detection using electrocardiogram (ECG) signal. The first SKF model uses McSharry's ECG dynamical model integrated in two Kalman filter (KF) models trained for normal and AB intervals. Whereas the second SKF model is established by using only the RR sequence extracted from ECG and two AR models to be fitted in normal and AB intervals. In both SKF approaches, a... 

Apnea-bradycardia (AB) is a common complication in prematurely born infants, which is associated with reduced survival and neurodevelopmental outcomes. Thus, early detection or predication of AB episodes is critical for initiating preventive interventions. To develop automatic real-time operating systems for early detection of AB, recent advances in signal processing can be employed. Hidden Markov Models (HMM) are probabilistic models with the ability of learning different dynamics of the real time-series such as clinical recordings. In this study, a hierarchy of HMMs named as layered HMM was presented to detect AB episodes from pre-processed single-channel Electrocardiography (ECG). For... 

In this paper, a method for apnea bradycardia detection in preterm infants is presented based on coupled hidden semi Markov model (CHSMM). CHSMM is a generalization of hidden Markov models (HMM) used for modeling mutual interactions among different observations of a stochastic process through using finite number of hidden states with corresponding resting time. We introduce a new set of equations for CHSMM to be integrated in a detection algorithm. The detection algorithm was evaluated on a simulated data to detect a specific dynamic and on a clinical dataset of electrocardiogram signals collected from preterm infants for early detection of apnea bradycardia episodes. For simulated data, the... 

In this paper, we present a novel framework for the coupled hidden Markov model (CHMM), based on the forward and backward recursions and conditional probabilities, given a multidimensional observation. In the proposed framework, the interdependencies of states networks are modeled with Markovian-like transition laws that influence the evolution of hidden states in all channels. Moreover, an offline inference approach by maximum likelihood estimation is proposed for the learning procedure of model parameters. To evaluate its performance, we first apply the CHMM model to classify and detect disturbances using synthetic data generated by the FitzHugh-Nagumo model. The average sensitivity and... 

TiO2 deposited on a membrane of Ag fibers was prepared as a photoelectrochemical cell electrode. Ag fibers were made by reduction of Ag complexes on cellulose fibers, followed by burning out the template. TiO 2 photocatalyst layers were grown on the fibers by electrophoretic deposition of TiO2 nanoparticles. Ag fibers could be uniformly deposited. Photocatalytic tests by dye decomposition and electrochemical impedance spectroscopy (EIS) under UV illumination demonstrate that Ag fibers act as a good substrate that provides both high surface area and good separation of photogenerated electron-hole pairs and causes the enhancement of photocatalytic activity in comparison with a thin film of... 

This study examines the air quality on line 1 and 2 of Tehran underground metro. The total suspended particulate (TSP), PM10, PM2.5, PM1, CO2, NO, NO2, SO2, relative humidity and air temperature were measured. An integrated air quality index was also calculated for each location. The results revealed that, PMlO, PM2.5, and SO2 concentrations are higher than their environmental standard levels. The in station CO2 levels are higher while its' in train levels are lower than environmental permissible level. The air quality index showed that the in-train air quality is more acceptable than the instation air quality  

Autonomous robotic grasping has emerged as a valuable capability for automating everyday household tasks like table setting (bossing), cleaning, and meal preparation. Still, accurately detecting and manipulating diverse everyday objects in unstructured home environments remains a significant challenge. In this study, an integrated robotic system combining YOLOv8s-seg deep learning for object detection and segmentation with computer vision techniques to determine optimal grasping points is proposed. The accuracy of this model has also been compared with other models through their mAP0.5, mAP.05-.95, precision and recall. A custom dataset of over 1000 images containing common household objects... 

Objective(s): The molecular basis of “metabolically healthy obese” and “metabolically unhealthy non-obese” phenotypes is not fully understood. Our objective was to identify metabolite patterns differing in obese (metabolically healthy vs unhealthy (MHO vs MUHO)) and non-obese (metabolically healthy vs unhealthy (MHNO vs MUHNO)) individuals. Materials and Methods: This case-control study was performed on 86 subjects stratified into four groups using anthropometric and clinical measurements: MHO (21), MUHO (21), MHNO (22), and MUHNO (22). Serum metabolites were profiled using nuclear magnetic resonance (NMR). Multivariate analysis was applied to uncover discriminant metabolites, and enrichment... 

Activated carbon powder was analyzed at one of the petro-chemical units in Iran, to determine the usefulness of this material in waste water treatment. Two types of commercial activated carbon powder were used giving different results, attributed to different constituents. For every experiment, 4 kg of activated carbon was used in the pilot plant column. Analysis results on the effect of parameters, e.g., inlet volumetric flow rate of waste water and activated carbon structure, on the plant performance were presented. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering (Prague, Czech Republic 8/24-28/2008)  

Hexyltriphenylphosphonium bromide (HTPB) is used as an efficient ionic liquid catalyst in the chemoselective addition of malononitrile to carbonyl group moiety of chalcones through the three-component reaction of aryl aldehydes, acetophenone derivatves, and malononitrile to produce (E)-2-(1,3-diarylallylidene)malononitriles at ambient temperature. The method is simple, solvent-free, environmentally friendly, and gives excellent yields in a short reaction times. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim  

Although simvastatin (SIM) has been proven to be a powerful agent against myocardial ischemia/reperfusion (MI/R) injury, poor water solubility, short half-life, and low bioavailability have made it futile while using conventional drug delivery system. Hence, this study aims to investigate therapeutic efficacy of SIM-loaded nano-niosomes on MI/R injury. Surface active agent film hydration method was used to synthesize nano-niosomes. The physicochemical properties of nano-niosomes were characterized using dynamic light scattering (DLS) and transmission electron microscopy (TEM). Moreover, niosomes were characterized in entrapment efficiency (EE) and releasing pattern. Male Wistar rats were... 

In thin-film solar cells, deposition of pinhole and the crack-free absorber layer, with the right chemical stoichiometry is highly important for high-performance solar cell devices. In solution-based CIGS solar cell technology, a nanoparticle ink approach provides phase stability of the final chalcogenide absorber layer. However, the sintering of small nanoparticles to form large grains with reduced grain boundaries is an important challenge in the fabrication process. This is usually realized by annealing in the Se atmosphere, i.e. selenization process. However, the presence of Ga in CIGS films leads to pinholes after selenization. In this study, the synthesis and deposition of high-quality... 

Although so many advances have been proposed in the field of artificial intelligence and superconductivity, there are few reports on their combination. On the other hand, because of the nonlinear and multivariable characteristics of the superconductive elements and capabilities of neural networks in this field, it seems useful to apply the neural networks to model and control the superconductive phenomena or devices. In this paper, a new constructive neural network (CNN) trained by two different optimization algorithms; back-propagation and genetic algorithm, is proposed which models the behavior of the superconductive fault current limiters (SFCLs). Simulation results show that the proposed... 

For the 4th IUPAP International Conference of Women in Physics, we report on activities in science and engineering in Iran, and conditions for women in physics, in the three years since the 3rd IUPAP International Conference of Women in Physics was held in 2008. Iran has made prominent advancements and astonishing progress in laser technology, biotechnology, nanotechnology, genetics, computer software and hardware, and robotics. Iranian scientists have been very productive in several experimental fields, such as pharmaceutical, organic, and polymer chemistry. Conditions for women in physics have improved greatly in recent years. A project to improve the environment for learning physics, and... 

Rare earths (REs) play a key role in distorting spinel structure by creating some defects at the lattice sites and make them suitable for magnetodielectric applications. In the present study, the nanoferrites of CuRE0.02Fe1.98O4, where REs = Y3+, Yb3+, Gd3+, were prepared using one step sol–gel method. The prepared samples are copper ferrite (CFO), yttrium doped copper ferrite (Y-CFO), ytterbium doped copper ferrite (Yb-CFO) and gadolinium doped copper ferrite (Gd-CFO), respectively. The single-phase structure of all the REs doped nanoferrites was determined by X-ray diffraction (XRD) analysis. The porosity, agglomerations and grain size of the REs doped copper ferrite were examined using... 

In this paper, LQG/LTR controller is designed for attitude control of the geostationary satellite at nominal mode. Usage actuator is the reaction wheel and control torque is determined by the LQR regulator. LQR controller signal has good performance, if all states are considered in feedback, but does not include model and sensors noises. Usage sensors are sun and earth sensors and EKF is used for estimation of noisy states. Then, LQG and LQG/LTR controllers are designed based on the estimated states, and are compared with LQR controller. The results show that robustness and performance of LQG/LTR are better than LQG and its control overshoot is smaller than LQR. The term that is provided in... 

Heteropoly acid was found to be an effective and efficient catalyst for the ring opening reaction of epoxides with various aromatic amines to produce the corresponding β-amino alcohols in moderate to excellent yields in water. This method provides a new and efficient protocol in terms of mild reaction conditions, clean reaction profiles, small quantity of catalyst, and simple work-up procedure