Sharif Digital Repository

Titania was deposited on glass fibers with a partial epoxy layer coating from a solution containing TiO2 nanoparticles at T = 90°C, and the adsorption process was examined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, and photocatalytic activity measurements. XPS data demonstrated that about 25% of the surface was covered with TiO2 nanoparticles, with 10% on the epoxy layer and 15% on the glass body. It was found that TiO2 nanoparticles can be readily adsorbed on epoxy groups, whereas they have a low tendency to adsorb on carbon polymer chains. This difference can be... 

The photocatalytic degradation of Reactive Blue 19 (RB19) dye has been studied using TiO2 nanofibre as the photocatalyst in aqueous solution under UV irradiation. Titanium dioxide nanofibre was prepared using a templating method with tetraisopropylorthotitanate as a precursor. The experiments were carried out in the presence of the TiO2 nanofibre, and the effects of pH and electron acceptors on the degradation process were investigated. In order to observe the quality of the aqueous solution, chemical oxygen demand (COD) measurements were also carried out before and after the treatments. The photocatalytic decomposition of RB19 was most efficient in acidic solution. With the addition of... 

Density of surface charges of cellulose fibers and -potential of TiO2 nanoparticles in the solution were measured and controlled by pH. The adsorption and clustering of TiO2 nanoparticles on the surface of cellulose fibers were studied using scanning electron microscopy (SEM) and a scale in different situations of repulsion and attraction between the particles and surface. The experiments show formation of two-dimensional clusters of nanoparticles on the surface. Weight measurement of the adsorbed particles and clusters via the adsorption time results in that there are three stages containing nucleation, two-dimensional growth and saturation for clustering of nanoparticles on the surface.... 

Lab-On-A-Disk, as a subfield of microfluidic systems, recently has drawn attention to being utilized in blood biomarker diagnosis, blood typing, and immunoassays because of being high-Throughput, highly precise, and easy to use. Blood plasma separation is a most vital unit for pre-processing in these systems, since the blood plasma contains a lot of proteins and enzymes that should be separated, and precisely examined. Therefore, in this paper, for the first time, a numerical model was proposed to evaluate the plasma separation in various time scales and geometries, and an appropriate design was proposed. Furthermore, because the blood plasma volume is different between patients, and the... 

Approximate computing is an emerging paradigm that can tolerate some loss of accuracy to improve the energy consumption and design complexity. Multiplication is one of the important computational components in various digital signal processing (DSP) applications. Improvement of multipliers, as the building blocks of an approximate computing systems, has received significant attention. Compressors are key elements in an approximate multiplier to have an optimal design with high performance. This paper proposes an approximate/exact 4–2 compressor and an exact 5–2 compressor in carbon nanotube field-effect transistors (CNTFET) technology for utilisation in an approximate multiplier. Four... 

Automatic induction of semantic verb classes is one of the most challenging tasks in computational lexical semantics with a wide variety of applications in natural language processing. The large number of Persian speakers and the lack of such semantic classes for Persian verbs have motivated us to use unsupervised algorithms for Persian verb clustering. In this paper, we have done experiments on inducing the semantic classes of Persian verbs based on Levin's theory for verb classes. Syntactic information extracted from dependency trees is used as base features for clustering the verbs. Since there has been no manual classification of Persian verbs prior to this paper, we have prepared a... 

This paper addresses design of an observer-based adaptive fuzzy controller for a class of single-input-single-output (SISO) nonlinear systems with unknown dynamics subject to input nonlinearity and unknown direction. The proposed controller is singularity free. A high-gain observer is designed to estimate the unmeasured states, and the Lipschitz condition for proving boundedness of the estimated states is relaxed. The Nussbaum function is used to handle the unknown virtual control directions and the backstepping technique has been applied for controller design. It is proved that all closed loop signals are semi-globally uniformly ultimately bounded (SGUUB) and the output tracking error... 

This paper addresses design of an observer-based adaptive fuzzy controller for a class of single-input–single-output (SISO) nonlinear systems with unknown dynamics subject to input nonlinearity and unknown direction. The proposed controller is singularity free. A high-gain observer is designed to estimate the unmeasured states, and the Lipschitz condition for proving boundedness of the estimated states is relaxed. The Nussbaum function is used to handle the unknown virtual control directions and the backstepping technique has been applied for controller design. It is proved that all closed loop signals are semi-globally uniformly ultimately bounded (SGUUB) and the output tracking error... 

In this paper, we consider the bacterial point-to-point communication problem with one transmitter and one receiver by considering the ligand receptor binding process. The most commonly investigated signalling model, referred to as the Level Scenario (LS), uses one type of a molecule with different concentration levels for signaling. An alternative approach is to employ multiple types of molecules with a single concentration level, referred to as the Type Scenario (TS). We investigate the trade-offs between the two scenarios for the ligand receptor from the capacity point of view. For this purpose, we evaluate the capacity using numerical algorithms. Moreover, we derive an upper bound on the... 

An ecofriendly one-pot multicomponent reaction of 1,3-dicarbonyl compounds, aldehydes, and malononitrile was carried out in a different deep eutectic solvent (DES) based on choline chloride, to synthesize highly functionalized benzopyran and pyran derivatives under catalyst-free conditions. The results showed that urea:choline chloride based DES is the best solvent and is successfully applicable to a wide range of aldehydes, active methylene compounds with high yields (75-95%) and short reaction times (1-4 h)  

This paper addresses the design of an observer based adaptive neural controller for a class of strict-feedback nonlinear uncertain systems subject to input delay, saturation and unknown direction. The input delay has been handled using an integral compensator term in the controller design. A neural network observer has been developed to estimate the unmeasured states. In the observer design, the Lipschitz condition has been relaxed. To solve the problem of unknown control directions, the Nussbaum gain function has been applied in the backstepping controller design. “The explosion of complexity” occurred in the traditional backstepping technique has been avoided utilizing the dynamic surface... 

Ankle-foot orthoses (AFOs) have been described to have positive effects on the gait biomechanics in stroke patients. The plantarflexion resistance of an AFO is considered important for hemiplegic patients, but the evidence is still limited. The purpose of this case series was to design and evaluate the immediate effect of an articulated AFO on kinematics and kinetics of lower-limb joints in stroke patients. The articulated AFO with the adjustment of plantarflexion resistance was designed. The spring generates a plantarflexion resistance of the ankle joint at initial stance phase. The efficacy of orthosis was evaluated on two stroke patients in 2 conditions: without an AFO and with the AFO.... 

Titania nanofibers were prepared using a colloidal solution of Titania nanoparticles and a templating method. The preparation comprises impregnation of cellulose fibers in the solution containing Titania nanoparticles followed by thermal removal of the cellulose template. It is evidenced by scanning electron microscopy (SEM) that the residue substance consists of micron size fibers with a microstructure of nanofibers. The pore size distribution of the substance is multi-scale and fractal morphology was demonstrated with two fractal regimes with dimensions of 1.78 and 2.97 for sizes below and above 7.5nm, respectively. The surface area of the Titania fibers was measured about 250m2/g. The... 

This paper addresses the design of an observer-based adaptive fuzzy controller for a class of uncertain non-strict nonlinear systems subject to time-delays, unknown direction, input saturation, and output constraint. The Barrier Lyapunov Function (BLF) has been utilized to keep the system output inside the desired bounds. The state and input delays have been handled by using the Lyapunov–Krasovskii function and including an integral compensator term in the controller, respectively. A state observer has been designed to estimate the unmeasured states. The Lipschitz condition for proving boundedness of the estimated states has been relaxed. The Nussbaum gain function has been exploited to deal... 

Ideal orientations are one of the material characteristics of the applied mode of deformation. The transfer of material texture to orientations near specific ideal orientations can improve the mechanical properties of the material. In this paper, we focus on the determination of ideal orientations of BCC crystals under the equibiaxial tension mode of deformation. To do this, an Euler space scanning method based on a crystal plasticity approach is presented. In this method some initial orientations which are evenly spaced in the Euler space are selected and their evolutions into the ideal orientations are tracked. The loading is applied incrementally until all of the lattice spin components... 

In some applications, the variance of measurement noise depends on the signal that we aim to measure. For instance, additive Gaussian signal-dependent noise (AGSDN) channel models are used in molecular and optical communication. Herein we provide lower and upper bounds on the capacity of additive signal dependent noise (ASDN) channels. We also provide sufficient conditions under which the capacity becomes infinity. © 2017 IEEE  

This paper investigates a range of empirical risk functions and regularization methods suitable for self-training methods in semi-supervised learning. These approaches draw inspiration from various divergence measures, such as f-di-vergences and α-Rényi divergences. Inspired by the theoretical foundations rooted in divergences, i.e., f-divergences and α-Rényi divergence, we also provide valuable insights to enhance the understanding of our empirical risk functions and regularization techniques. In the pseudo-labeling and entropy minimization techniques as self-training methods for effective semi-supervised learning, the self-training process has some inherent mismatch between the true label...