Sharif Digital Repository

Zirconia Toughened Alumina (ZTA) Nanocomposites were prepared using Nano sized Zirconia (ZrO2) powders doped with 3% mol of yttria (Y 2O3) nanopowders. Diffusion of α-alumina (Al 2O3) nanoparticles as well as yttria into the Zirconia lattice network drives monoclinic - tetragonal martensitic transformation. Zirconia toughened alumina (ZTA) composites containing different amount of partially stabilized Zirconia (PSZ) 5, 10, 15 and 20% mol, were prepared via wet mixing and axial pressing. After sintering at different temperatures,1450, 1550 and 1650 °C, phase change in the samples were monitored. X-ray diffraction patterns showed that at constant composition, tetragonal zirconia was increased... 

The present work studied bioactive coatings on the surface of ceramic biomaterials. Zirconia toughened alumina (ZTA) composites containing 15 mol.-%. Partially stabilised zirconia was prepared after 1 h sintering at 1550°C. Apatite layers were then coated onto the surfaces of composites by the biomimetic method using 1·5-2 multiply concentrations of simulated body fluid (SBF). Before treatment in SBFs, a sodium silicate layer was employed as nucleating agent to induce the formation of a calcium phosphate layer. The effect of immersion time on the morphology of the precipitate was monitored with a scanning electron microscope. X dot maps revealed that there is a relationship between... 

The low erosion resistance of titanium and its alloys has prevented their widespread application as joint implants. In addition, one essential requirement for the implants to bond with the living bone is the formation of a bone-like apatite on their surfaces in the host body. To enhance the erosion resistance of the surface, a diffused layer of TiB2 was formed at 1000uC on the commercial pure titanium. Hydroxyapatite was then coated on the boronised titanium by means of dip coating in a sol-gel solution. In order to confirm the biocompatibility of the specimens, they were soaked in a simulated body fluid for several days. The surface morphology of the specimens after exposure was studied by... 

The interest in wearable systems among the biomedical engineering and clinical community continues to escalate as technical refinements enhance their potential use for both indoor and outdoor applications. For example, an important wearable technology known as a microelectromechanical system (MEMS) is demonstrating promising applications in the area of biomedical engineering. Accordingly, this study was designed to investigate the Sharif-Human Movement Instrumentation System (SHARIF-HMIS), consisting of inertial measurement units (IMUs), stretchable clothing, and a data logger—all of which can be used outside the controlled environment of a laboratory, thus enhancing its overall utility.... 

As the ordinary least squares (OLS) method is very sensitive to outliers as well as to correlated responses, a robust coefficient estimation method is proposed in this paper for multi-response surfaces in multistage processes based on M-estimators. In this approach, experimental designs are used in which the intermediate response variables may act as covariates in the next stages. The performances of both the ordinary multivariate OLS and the proposed robust multi-response surface approach are analyzed and compared through extensive simulation experiments. Sum of the squared errors in estimating the regression coefficients reveals the efficiency of the proposed robust approach. © 2018 Taylor... 

As the ordinary least squares (OLS) method is very sensitive to outliers as well as to correlated responses, a robust coefficient estimation method is proposed in this paper for multi-response surfaces in multistage processes based on M-estimators. In this approach, experimental designs are used in which the intermediate response variables may act as covariates in the next stages. The performances of both the ordinary multivariate OLS and the proposed robust multi-response surface approach are analyzed and compared through extensive simulation experiments. Sum of the squared errors in estimating the regression coefficients reveals the efficiency of the proposed robust approach. © 2017 Taylor... 

In this article, we investigate the problem of practical output regulation, i.e., to design a controller that brings the system output in the vicinity of a desired target value while keeping the other variables bounded. We consider uncertain systems that are possibly nonlinear and the uncertainty of their linear parts is modeled element wise through a parametric family of matrix boxes. An optimization-based design procedure is proposed that delivers a continuous-time control and estimates the maximal regulation error. We also analyze an event-triggered emulation of this controller, which can be implemented on a digital platform, along with an explicit estimate of the regulation error. ©... 

Rank aggregation, that is merging multiple ranked lists, is a pivotal challenge in many information retrieval (IR) systems, especially in distributed IR and multilingual IR. From the evaluation point of view, being able to calculate the upper-bound of performance of the final aggregated list lays the ground for evaluating different aggregation strategies, independently. In this paper, we propose an algorithm based on dynamic programming which, using relevancy information, obtains the aggregated list with the maximum performance that could be possibly achieved by any aggregation strategy. We also provide a detailed proof for the optimality of the result of the algorithm. Furthermore, we... 

In this research, the effect of beam buckling in a predefined direction is used to reduce occupant injuries in frontal crashes of an ultra-low-floor (ULF) city bus. In ULF buses, the floor structure consists of several longitudinal long beams, which in case of a frontal crash may buckle due to the axial impact. The direction of rotational acceleration of the driver seat due to buckling is highly affected by the position of the driver seat. A finite element model of an ULF bus was developed using LS-Dyna. The driver model, a Hybrid III 50 th male dummy with deformable jacket and abdomen, was restrained to the seat with a 3-point belt. An Elastic-Plastic material model was used for the bus... 

This paper simulates Al2O3-water nanofluid flow and forced convection around a rotating circular cylinder. The governing parameters are Reynolds number (1 ≤ Re ≤ 100), solid volume fraction of nanoparticles (0 ≤ φ ≤ 0.05) and non-dimensional rotation rate (0 ≤ α ≤ 3). The simulations are performed to study the effects of mentioned parameters on the heat transfer rate and fluid flow characteristics. The governing equations including the continuity, momentum, and energy equations are solved with a finite volume method. It is observed that the reduction of heat transfer with increase in rotation rate is in the vicinity of 6.9% and 32% for Re = 5 and 100, respectively at φ = 0.05. Furthermore,... 

This paper addresses the problem of optimal state-feedback design for a class of non-linear systems. The method is applicable to all non-linear systems which can be linearised using the method of state-feedback linearisation. The alternative is to use linear optimisation techniques for the linearised equations, but then there is no guarantee that the original non-linear system behaves optimally. The authors use feedback linearisation technique to linearise the system and then design a state feedback for the feedback-linearised system in such a way that it ensures optimal performance of the original non-linear system. The method cannot ensure global optimality of the solution but the global... 

In this short note we apply methods introduced by B. Hanke and T. Schick to prove the vanishing of (low degree) higher Â-genera for spin manifolds admitting a positive scalar curvature metric. Our aim is to provide a short proof for this beautiful result  

There are various cases in physics and engineering sciences (especially communications) where one requires the envelope probability density function (pdf) of the sum of several random sinusoidal signals. According to the correspondence between a random sinusoidal signal and a random vector, the sum of random vectors can be considered as an abstract mathematical model for the above sum. Now it is desired to obtain the pdf of the length of the resulting vector. Considering the common and reasonable assumption of uniform distributions for the angles of vectors, many researchers have obtained the pdf of the length of the resulting vector only for special cases. However in this paper, the pdf is... 

Purpose - the purpose of this study is the measuring of the human movement using printed wearable sensor. Human movement measurement is one of the usages for wearable sensors. This technology assists the researchers to collect data from the daily activities of individuals. In other words, the kinematics data of human motion will be extracted from this data and implemented in biomechanical aspects. Design/methodology/approach - This study presents an innovative printed wearable sensor which can be used for measuring human movement orientations. In this paper, the manufacturing process, implementation, measurement setup and calibration procedure of this new sensor will be explained, and the... 

Nowadays, data and information are recognized as a precious resource in an organization. Data quality indicators help organizations manage the quality of data quantitatively and improve organizational processes. Organizations manage data and information with the help of information systems and make decisions within the framework of data collected and analyzed. On the other hand, continuous evaluation of the quality of data flow in systems can lead to a preventive program to formulate strategies for improving performance. This can be done effectively and efficiently in the form of control charts. In this paper, control charts are employed to monitor the quality of data flow in information... 

Two room temperature liquid salts containing molybdenum(VI), [BMIM] 2[MoO2(NCS)4] (1) and [DMIM] 2[MoO2(NCS)4] (2), were immobilized on ionic liquid-modified silica leading to materials which showed notable catalytic activity for the reduction of sulfoxides into sulfides with triphenylphosphine (PPh3). The molybdenum liquid salts immobilized on the supported ionic liquid phase could be reused at least for three catalytic cycles without significant loss of activity  

CPU caches are powerful sources of information leakage. To develop practical cache-based attacks, the need for automation of the process of finding exploitable cachebased side-channels in computer systems is felt more than ever. Cache template attack is a generic technique that utilizes Flush+Reload attack in order to automatically exploit cache vulnerability of Intel platforms. Cache template attack on the T-table-based AES implementation consists of two phases including the profiling phase and key exploitation phase. Profiling is a preprocessing phase to monitor dependencies between the secret key and behavior of the cache memory. In addition, the addresses of T-tables can be obtained... 

Objective(s): Multiple sclerosis (MS) is considered as a chronic type of an inflammatory disease characterized by loss of myelin of CNS. Recent evidence indicates that Interleukin 17 (IL-17)-producing T helper cells (Th17 cells) population are increased and regulatory T cells (Treg cells) are decreased in MS. Despite extensive research in understanding the mechanism of Th17 and Treg differentiation, the role of microRNAs in MS is not completely understood. Thereby, as a step closer, we analyzed the expression profile of miR-9-5p and miR-106a-5p, and protein level of retinoic acid receptor (RAR)-related orphan receptor C (RORC; Th17 master transcription factor) as direct target of miR-106a-5p... 

The inventory replenishment policy exploited by a supply chain has a principle role in amplification of order variability compared to fluctuations in customers' demands. This phenomenon is known as the bullwhip effect. In this paper, a four echelon supply chain is simulated and the impacts of continuous and periodic review order-up-to policies on the bullwhip effect are examined. Experiments have been conducted to analyze the influence of the lead time in deterministic conditions, and also the variance of demand and lead time in stochastic circumstances on the bullwhip effect and the corresponding cost. It was observed that in low demand and lead time variances, it is more efficient to... 

In this study, Ni-Fe/SiC nanocomposite coatings with smooth and crack-free surface were successfully prepared by means of the conventional electrodeposition in the presence of saccharin in electrolyte. The goal of this work was to investigate the effect of SiC nanoparticles and saccharin on the structure and properties of permalloy nanocomposite coatings. The nanocomposite coatings were characterized using optical and scanning electron microscopy, energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) technique. The significant variation in the crystallographic texture of the coatings was observed due to the addition of SiC nanoparticles and saccharin in the electrodeposition...