Sharif Digital Repository

This paper presents the background of low back problem caused by repetitive fatigue loading. We emphasize on mechanism of Intervertebral Disc (IVD) and conditions for which the disc does not recover its original status under repetitive work and cause low back pain. The objective of this study is to identify structural changes in system parameters for fatigue loaded intervertebral disc. Principal component analysis (PCA) is used for studying the behavioral change of spine against cyclic loading as a function of time. Percentage difference and similarity factor was calculated for the analysis. Specimens were applied with impulse testing to measure the stiffness and acceleration after fracture,... 

This paper presents recent developments on effects of rest and fatigue loading on properties of healthy vertebra discs. A comparison of different approaches used in literature to study the properties of intervertebral disc is presented. The major achievements in this area so far are discussed in the context of their advantages and disadvantages. The past approaches are based on bio-mechanical models which mostly used statistical techniques for the analysis and estimation of fatigue loaded Intervertebral Disc (IVD). However, those modeling techniques were not flexible enough for analysis of customized tests. In this paper, we applied System Identification (SI) based NLARX modeling technique... 

This paper focuses on characterization of intervertebral disc behavior upon fatigue stress. It consists in in-vitro experiments to measure intervertebral disc deformation with regard to forces applied to produce fatigues test. In this paper, a system modeling based non-invasive method to assess back pain is proposed which may be used for designing of prediction model to predict the failure of intervertebral disc (IVD) experiencing fatigue loading. An artificial compression fracture was simulated in the lower level of vertebra followed by a poly(methyl methacrylate) (PMMA) bone cement injection. Fatigue loading was applied on the specimens and the load was incrementally increased form 650 N... 

This paper presents the design performance characteristics of a novel Robotic Mannequin, “RoMa”, developed for the fashion industry. RoMa, a full-body humanoid social robot platform, is currently in the final stages of development for visual merchandising to promote customer appeal. RoMa is characterized by nine features which are listed as: appealing appearance, avoiding the uncanny valley, easy maintenance, interactive, light weight, low developmental cost, suitable body movements, suitable color, and user friendly. In this paper, important design procedures and considerations are briefly presented and discussed. © 2017, Springer International Publishing AG  

We consider two ensembles of qubits dissipating into two overlapping environments, that is, with a certain number of qubits in common that dissipate into both environments. We then study the dynamics of bipartite entanglement between the two ensembles by excluding the common qubits. To get analytical solutions for an arbitrary number of qubits we consider initial states with a single excitation and show that the largest amount of entanglement can be created when excitations are initially located among side (noncommon) qubits. Moreover, the stationary entanglement exhibits a monotonic (nonmonotonic) scaling versus the number of common (side) qubits  

We consider a model of a bosonic memory channel, which induces correlations among the transmitted signals. The application of suitable unitary transformations at the encoding and decoding stages allows the complete removal of correlations, thereby mapping the memory channel into a memoryless one. However, such transformations, being global over an arbitrarily large number of bosonic modes, are not realistically implementable. We then introduce a family of efficiently realizable transformations, which can be used to partially remove correlations among errors, and we quantify the reduction of the gap with memoryless channels  

We characterize the completely positive trace-preserving maps on qutrits (qutrit channels) according to their covariance and symmetry properties. Both discrete and continuous groups are considered. It is shown how each symmetry group restricts arbitrariness in the parameters of the channel to a very small set. Although the explicit examples are related to qutrit channels, the formalism is sufficiently general to be applied to qudit channels  

In this paper, a new simple and complete technique of modeling and analysis of a matrix converter is presented based on the singular value decomposition (SVD) of modulation matrix. The proposed modeling method yields a new limitation between the matrix converter gain and its input power factor, which is more relaxed as compared to the limits reported so far in the literature. The SVD of the modulation matrix leads to a unified modulation technique which achieves the full capability of a matrix converter. It is shown that this approach is general and all other modulation methods established for a matrix converter are specific cases of this technique. The proposed modulation method can be used... 

Scale formation is one of the major problems in oilfields. Removal of scales is a difficult process due to their relative hardness and low solubility. Therefore it is valuable to find a method which can remove damages caused by scales. Ultrasonic radiation is known have the sufficient energy to remove the scales. Our purpose is to investigate the role of ultrasound on permeability increments due to scale removal. Some experiments were carried out to find these effects and observed that ultrasound has increased volumetric mass transfer, concentration and solubility limits. We also worked on a model presented by Tahmasebi et. al[2010] and applied changes on it to make it able to predict... 

In this paper, the reactive power control of a variable-speed permanent-magnet synchronous wind generator with a matrix converter at the grid side is improved. A generalized modulation technique based on singular value decomposition of the modulation matrix is used to model different modulation techniques and investigate their corresponding input reactive power capability. Based on this modulation technique, a new control method is proposed for the matrix converter which uses active and reactive parts of the generator current to increase the control capability of the grid-side reactive current compared to conventional modulation methods. A new control structure is also proposed which can... 

We study the Kitaev-Ising model, where ferromagnetic Ising interactions are added to the Kitaev model on a lattice. This model has two phases which are characterized by topological and ferromagnetic order. Transitions between these two kinds of order are then studied on a quasi-one-dimensional system, on a ladder, and on a two-dimensional periodic lattice, a torus. By exactly mapping the quasi-one-dimensional case to an anisotropic XY chain we show that the transition occurs at zero λ, where λ is the strength of the ferromagnetic coupling. In the two-dimensional case the model is mapped to a two-dimensional Ising model in transverse field, where it shows a transition at a finite value of λ.... 

In this study, operation of the contact Cylindrical Capacitive Sensor (CCS) for the reactance capacitance measurement of the water liquids by using the charge/discharge measurement module is investigated. The effect of geometric factor on the capacitance measurement of different liquid samples is also studied. The measured capacitances for the distilled, mineral, tap and salt water samples are reported by using two contact CCSs with the active length of 16 and 74 mm. The measured capacitances by small contact CCS for the saltwater is 1.76 uF and by big contact CCS is 47.8 uF, which shows a big difference for different probes. In another study, the effects of the liquid conductance on the... 

Local noise can produce quantum correlations on an initially classically correlated state, provided that it is not represented by a unital or semiclassical channel. We find the power of any given local channel for producing quantum correlations on an initially classically correlated state. We introduce a computable measure for quantifying the quantum correlations in quantum-classical states, which is based on the noncommutativity of ensemble states in one party of the composite system. Using this measure we show that the amount of quantum correlations produced is proportional to the classical correlations in the initial state. The power of an arbitrary channel for producing quantum... 

Let L be a reversible Markovian generator on a finite set V. Relations between the spectral decomposition of L and subpartitions of the state space V into a given number of components which are optimal with respect to min-max or max-min Dirichlet connectivity criteria are investigated. Links are made with higher-order Cheeger inequalities and with a generic characterization of subpartitions given by the nodal domains of an eigenfunction. These considerations are applied to generators whose positive rates are supported by the edges of a discrete cycle Z N, to obtain a full description of their spectra and of the shapes of their eigenfunctions, as well as an interpretation of the spectrum... 

In this study the kinetic modeling of visbreaking reactions for a number of vacuum residue feeds was investigated using available experimental data from the literature. A continuous lumping model was developed for kinetic analysis of visbreaking reactions. The normalized boiling point was used to describe each feed as a continuous mixture and the concentration distribution of the mixture would change under reaction conditions. A continuous model with five adjustable parameters was used to describe visbreaking reactions, and these parameters were optimized for each feed for reaction temperatures in the range of 400-430 C using available experimental data. The model was able to accurately... 

Design and operation of three different optical sensors based on the intensity modulation are reported in this article. These sensors are measuring absence or presence of any liquid and the measurement variable is refractive index and optical absorption. Reported devices can also check the presence of air bubbles in the liquid flow line. Performance of these sensors is tested as a liquid flow monitoring device while using different light sources. Sensor #1 uses a simple cell with the long transmitter and receiver optical fibers. Sensor #2 utilizes a small cell assembly that includes the short transmitter and receiver fibers. Sensor #3 employs a quartz flow cell with the direct light... 

In this paper we define Broadcast Relay Networks (BRN) with two relays. There are a transmitter, two relays and two receivers in the network. We find an achievable rate region for it by considering full cooperation between relays. We use symmetric relaying method at relays and Marton's broadcast code construction for the transmitter.We will show that Kramer's rate region for Broadcast Relay Channel (BRC), Ghabeli's rate for symmetric two-relay network, and Marton's rate region for Broadcast Channel are special cases of our achievable rate region  

A matrix converter is a voltage/current source AC/AC frequency converter. In grid-connected operation of a variable-speed permanent magnet synchronous wind power generator, the matrix converter is normally controlled as a voltage source converter. In this control method, the generator-side voltage is synthesized from the grid-side voltage source. However, in the stand-alone mode of operation, the grid-side stiff voltage source is not available, and the input filter of the matrix converter is unstable. In this article, a new control method is presented that controls a permanent magnet synchronous wind generator in a stand-alone mode with a matrix converter as a current source converter. The... 

A novel electrochemical sensor based on nanocellulose-carbon nanoparticles (NC-CNPs) nanocomposite film modified glassy carbon electrode (GCE) is developed for the analysis of metoclopramide (MCP). Atomic force microscopy, scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the roughness, surface morphology and performance of the deposited modifier film on GCE. SEM image demonstrated that modifier nanoparticles are uniformly deposited on GCE, with an average size of less than 50nm. The electrochemical behavior of MCP and its oxidation product is studied using linear sweep and cyclic voltammetry over a wide pH range on NC-CNPs modified glassy... 

We investigate the correlation properties of separable two-qubit states with maximally mixed marginals. These states are divided to two sets with the same geometric quantum correlation. However, a closer scrutiny of these states reveals a profound difference between their quantum correlations as measured by more probing measures. Although these two sets of states are prepared by the same type of quantum operations acting on classically correlated states with equal classical correlations, the amount of final quantum correlation is different. We investigate this difference and trace it back to the hidden classical correlation which exists in their preparation process. We also compare these...