Sharif Digital Repository

Governments in developing countries have invested in institutions of higher learning in order to develop homegrown, high technology products. Among these, the National University of Malaysia (Universiti Kebangsaan Malaysia), recognized as a Research University, is actively involved in projects related to medical technology through its various faculties. The net result of these activities is impressing from the point of view of patents and publications, but unfortunately not yet in terms of commercialization. This paper starts by presenting the main obstacles towards the objective of bringing a laboratory prototype to the market in the context of Malaysia. Then, a framework is presented... 

In this paper, system identification techniques are applied to accurately characterize the frequency behavior of a commercially available but with unknown characteristics of a photoplethysmography (under the commercial name of Pulse Sensor). Although claimed to be open-source, the electronic schematic of this device does not allow for a full characterization of it. Therefore a second order auto-regressive with exogenous input model has been employed to find the frequency response of this system. An optical excitation circuit was developed to send a pseudo-random signal to the Pulse Sensor. Results show that the model is able to reproduce the output with a fitness of 89.7 %. The obtained... 

In this paper, we propose CodedSketch, as a distributed straggler-resistant scheme to compute an approximation of the multiplication of two massive matrices. The objective is to reduce the recovery threshold, defined as the total number of worker nodes that the master node needs to wait for to be able to recover the final result. To exploit the fact that only an approximated result is required, in reducing the recovery threshold, some sorts of pre-compression are required. However, compression inherently involves some randomness that would lose the structure of the matrices. On the other hand, considering the structure of the matrices is crucial to reduce the recovery threshold. In... 

In this paper, we introduce limited-sharing multiparty computation; in which there is a network of workers (processors) and a set of sources, each having access to a massive matrix as a private input. These sources aim to offload the task of computing a polynomial function of the matrices to the workers, while preserving the privacy of data. We also assume that the load of the link between each source and each worker is upper bounded by a fraction of each input matrix for some cin{1, rac{1}{2},rac{1}{3}, ldots}. The objective is to minimize the number of workers needed to perform the computation, such that even if an arbitrary subset of t-1 workers, for some tin mathbb{N}, collude, they... 

In this paper, we propose CodedSketch, as a distributed straggler-resistant scheme to compute an approximation of the multiplication of two massive matrices. The objective is to reduce the recovery threshold, defined as the total number of worker nodes that the master node needs to wait for to be able to recover the final result. To exploit the fact that only an approximated result is required, in reducing the recovery threshold, some sorts of pre-compression are required. However, compression inherently involves some randomness that would lose the structure of the matrices. On the other hand, considering the structure of the matrices is crucial to reduce the recovery threshold. In... 

Spectral Subtraction (SS), as a speech enhancement technique, originally designed for improving quality of speech signal judged by human listeners. it usually improve the quality and intelligibility of speech signals, while the speech recognition systems need compensation techniques capable of reducing the mismatch between the noisy speech features and the clean models. This paper proposes a novel approach for solving this problem by considering the SS and the speech recognizer as two interconnected components, sharing the common goal of improved speech recognition accuracy. The experimental evaluations on a real recorded database and the TIMIT database show that the proposed method can... 

In general coding theory, we often assume that error is observed in transferring or storing encoded symbols, while the process of encoding itself is error-free. Motivated by recent applications of coding theory, in this paper, we consider the case where the process of encoding is distributed and prone to error. We introduce the problem of distributed encoding, comprised of a set of K ∈ N isolated source nodes and N ∈ N encoding nodes. Each source node has one symbol from a finite field, which is sent to each of the encoding nodes. Each encoding node stores an encoded symbol from the same field, as a function of the received symbols. However, some of the source nodes are controlled by the... 

In this article, we consider a secure multi-party computation problem (MPC), where the goal is to offload the computation of an arbitrary polynomial function of some massive private matrices (inputs) to a cluster of workers. The workers are not reliable. Some of them may collude to gain information about the input data (semi-honest workers). The system is initialized by sharing a (randomized) function of each input matrix to each server. Since the input matrices are massive, each share's size is assumed to be at most 1/k fraction of the input matrix, for some k ∈ N. The objective is to minimize the number of workers needed to perform the computation task correctly, such that even if an... 

An enhancement in heat transfer due to nanofluids is essentially required in various thermal systems. Hybrid nanofluids possess high thermal conductivity and, have ability to embellish and enhance the thermal strength of common fluids. Our concern in this paper is to examine the innovative attributes of hybrid nanofluids like Manganese zinc ferrite (MnZnFe2O4) and Nickel zinc ferrite (NiZnFe2O4) in the bio-convective flow of motile gyrotactic microorganisms subject to Darcy Forchheimer medium. The effect of activation energy has also been taken into account. Mathematical treatment is carried out via MATLAB software. The use of MnZnFe2O4 - NiZnFe2O4/H2O exhibits improved thermal... 

Various natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using ceric-initiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT-IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer-free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were... 

Increasing efficiency, improving energy consumption, and optimizing energy in industries are more than ever considered by researchers. Some methods such as nanoparticles use and porous medium are used to increase the heat transfer rate. For this reason, in this paper, simulation and optimization of a two-dimensional tube with the presence of water–silver nanofluid and porous media have been performed to improve heat transfer. Different profiles of the rate, pressure, and temperature of the two-dimensional tube at volume fraction, porosity coefficient and Darcy numbers have been obtained and finally, the results are compared. Then, the Nusselt number and the friction coefficient in the range... 

In this work1, we consider the problem of secure multi-party computation (MPC), consisting of F sources, each has access to a large private matrix, N processing nodes or workers, and one master. The master is interested in the result of a polynomial function of the input matrices. Each source sends a randomized functions of its matrix, called as its share, to each server. The workers process their shares in interaction with each other, and send some results to the master such that it can derive the final results. There are several constraints: (1) each worker has a constraint on its storage, such that it can store equivalent of displaystyle rac{1}{m} fraction of size of each input matrices... 

The purpose of this work is to interpret cardiotocograph recordings by estimating kubli score in order to find out the presence of antepartum morbidity in cardiotocograph (CTG) recordings. The Kubli score is a tool used to evaluate a non-stress test (NST). It works very much like an Apgar Score in that there are 5 criteria to be assessed, baseline rate, amplitude of fluctuations, frequency of fluctuations, deceleration and acceleration pattern, and each will be assigned a score of 0, 1, or 2, for a maximum total of 10. The advantage of the Kubli score is that it is systematic and specific. This communication tool helps clinicians to have a visual image of the immediate fetal status. Using... 

Local educational institutions produce in-house English for Specific Purpose (ESP) materials according to the curriculum policies designated and developed by the Ministry of Higher Education In Iran. To this end, this book aims to be used in the Iranian setting at the tertiary level for undergraduate students majoring in Mechanical Engineering. Moreover, the style of English usage in this ESP textbook is American.
Regarding the content of the textbook, it has both thematic organizations in which the topics are relevant and includes sufficient treatment of the target language areas necessary for the students. The principle organizing approach of this textbook is theme-based. In addition,... 

The potentials of carbon nanotubes (CNTs) as mechanical resonators for atomic-scale mass sensing are presented. To this aim, a nonlocal continuum-based model is proposed to study the dynamic behavior of bridged single-walled carbon nanotube-based mass nanosensors. The carbon nanotube (CNT) is considered as an elastic Euler–Bernoulli beam with von Kármán type geometric nonlinearity. Eringen’s nonlocal elastic field theory is utilized to model the interatomic long-range interactions within the structure of the CNT. This developed model accounts for the arbitrary position of the deposited atomic-mass. The natural frequencies and associated mode shapes are determined based on an eigenvalue... 

Accelerograms recorded near active faults have some important characteristics that make them different from those recorded in far-fault regions. High-frequency components in acceleration records and long-period velocity pulses are among notable specifications of such ground motions. In this paper, a moving average filtering with appropriate cut-off frequency has been used to decompose the near-fault ground motions into two components having different frequency contents: first, Pulse-Type Record (PTR) that possesses long-period pulses; second, the relatively high-frequency BackGround Record (BGR), which does not include large velocity pulses. Comparing the results with those extracted through... 

Dyslipidemia is considered to be one of the main heart risk factors, affecting the endothelial vascular function, which can be non-invasively investigated by ultrasound flow-mediated dilation (US-FMD). However, US-FMD comes at a high-cost and is operator-dependent. In this paper, the effect of dyslipidemia on the photoplethysmogram (PPG) signal recorded from collateral index fingers is investigated following a previous study where it was shown that results similar to that of US-FMD can be replicated by the PPG. Two groups, consisting of 30 healthy subjects free from any risk factors and 30 subjects who have only dyslipidemia as risk factor were respectively considered. The percent change in... 

In an effort to identify a useful noninvasive screening tool for cardiovascular diseases (CVD) screening, photoplethysmograph (PPG) signals were acquired and analyzed. These PPG signals were recorded during reactive hyperemia experiments consisting of a 4-minute blood flow blockage of the right arm (RA) brachial artery (BA) using a blood pressure cuff inflator. This procedure is usually done for the assessment of endothelial dysfunction which is a risk factor for developing CVD. In this study, signals of the infrared (IR) and red (R) LED's of the PPG sensor were analyzed. These signals were preprocessed, normalized and slow varying component of the signal (DC values) and the pulsatile... 

Noninvasive measurement of brachial artery (BA) flow mediated dilation (FMD), commonly measured by high resolution ultrasonography, has provided a non-invasive means for the evaluation of endothelial function. Recently, another technique based on finger photopletysmogram (PPG) analysis has been proposed by the authors. In this paper, simultaneous measurement of BA FMD and PPG signals data from 86 human subjects (43 healthy and 43 risk) is analyzed and a statistical model is proposed to estimate the BA FMD based on PPG signals, the BA diameter at baseline as well as other demographics factors such as age and gender. Linear regression by multivariate analysis was conducted to obtain the... 

Photoplethysmography is a non-invasive method which is suitable to estimate vascular compliance. Photoplethysmogram (PPG) waveform has been used to evaluate vascular characteristic changes due to exercise. Quantification of the primary and secondary peak position is of interest as a potential objective, individualized measure of the level of exercise that a subject has achieved with respect to a baseline status, prior to the beginning of the exercise session. The modified bicycle ergonomic protocol was selected for this experiment. Two different signal processing methods were employed in processing the PPG waveform to characterize its changes through a single parameter. Both, the visual...