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Salep composite films containing 0±30% (w/w)  oleic acid or stearic acid – were prepared through emulsification and their physical, mechanical, and barrier properties were evaluated and compared. Emulsified films were softer than pure films. Addition of the fatty acids to salep films significantly improved the WVP (P<0.05), but lowered the tensile strength. Stearic acid was more effective than oleic acid in reducing the WVP, but films with oleic acid showed better mechanical properties overall than those with stearic acid . Also the presence of fatty acids decreased solubility in water and caused the films to become opaque. On the other, fatty acids showed different effects on the elongation at break. This work showed that when taking all the studied variables into account, films formulated with oleic acid were found most suitable for various food applications.  

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The objective of this research was to investigate the feasibility of edible film made from salep in which the hydrophobicity of film was modified by using stearic acid as a lipid agent. In addition its mechanical, thermal, permeability and color changes of film were analyzed. For this purpose, edible composite films were prepared from salep, stearic acid, and tween 80 in emulsion form using an ultra turax apparatus. The water vapor permeability (WVP) of the emulsified films was reduced by fatty acid addition. Also the permeability to oxygen of the emulsified films was lower than that of a salep film without fatty acid, but the difference was not significant in higher concentration of stearic acid. Scanning electron microscopy (SEM) was also used in order to analyze films microstructure. Finally, differential scanning calorimetry showed that the glass transition temperature (Tg) of the salep film was 12 °C and was considerably affected by stearic acid concentration.

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In the present paper, mixed convection of TiO2-water nanofluid in a laminar flow within a vertical rectangular duct is investigated numerically. A single phase and a two phase method is applied to simulate nanoparticles dispersion in the base fluid. An Euler-Lagrange approach is employed to track particles individually. In this approach, the base fluid is assumed to be a continuous phase while the particles are dispersed through it. The presence of particles in the base fluid is modeled as a source term in the momentum and energy equations. Governing equations is discretized using Control Volume based Finite Element Method (CVFEM). Effects of nanoparticles concentration, particles size, aspect ratio of cross section, asymmetrical boundary condition and buoyancy on the hydrodynamics and thermal parameters are presented and discussed. It is observed that increasing nanoparticles concentration enhances heat transfer rate and this enhancement is more considerable in higher aspect ratios. Also, at smaller values of Richardson number (Ri) where the effect of forced convection is more than natural convection, dispersion of nanoparticles in the base fluid improves heat transfer rate more considerably. Whilst an improvement in convective heat transfer is shown to be more than 6.5% at Ri=0.05, it does not exceed 4% at Ri=0.5.

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A nonlinear model for Autonomous Underwater Vehicles is proposed. In order to describe a more precise dynamic behavior, the nonlinear model for both Lateral and Longitudinal subsystems is derived based on all applied forces and moments. The proposed model can be explained as an extended linear model for AUV in depth and azimuth motions where some nonlinearities are taken into account. Due to some practical issues as well as the form of proposed model, the identification problem based on Least Square method is formulated to achieve the system parameters. By considering unstable dynamic of system, the open loop system cannot be excited. In this case, the PID regulators with simple tuning parameters are proposed in both Lateral and Longitudinal subsystems and the identification problem by utilizing sinusoidal inputs is followed within a feedback loop. Based on measurable variables i.e. linear moments, angular velocities and Euler angles, and utilizing some dynamic filters, the Least Square method is then applied to estimate the model parameters. The effectiveness of proposed nonlinear model as well as the parameter identification approach are finally demonstrated through some numerical simulations.

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From a statistical perspective, internal erosion and piping are from the main causes of failure in earth-rockfill dams. If these dams were located in a narrow valley, the steep slopes of the valley walls can cause increasing in stress transfer in the core. Therefore, the occurrence of hydraulic fracturing phenomenon in this kind of dams is more probable. Bidvaz dam is an earth-rockfill dam with a thin inclined clay core. The dam is located in the Northeast of Iran with a distance of twenty kilometers from the Esfrayen city. It has a height of 66 meters from the foundation and constructed in a narrow valley with a width of 40 meters on river bed and a wall slope of more than 60 degrees relative to horizontal direction. After about seven and a half years of starting first filling, a subsidence was observed at the upstream slope surface of this dam. The initial assessments, based on the data recorded in instruments which were installed inside the body and dam foundation, show at the lower level of the core and adjacent to left abutment, pore water pressure gradually has been increasing and finally reached to the reservoir water pressure, and at the same time effective stress with abnormal rate reduced to zero. These observations confirm the occurrence of internal erosion in the lower levels of the core adjacent to the left abutment. Due to the steep valley walls and noticeable difference of compressibility properties between the core and shell materials, it is expected occurring significant stress transfer in the core especially adjacent to the valley walls. Therefore, the hydraulic fracturing can be considered as a main cause initiating the process of internal erosion in this dam. The main objective of this paper is to assess the validity of this hypothesis. To achieve this purpose, this paper used a three-dimensional numerical model to simulate the behavior of the dam during construction and reservoir filling. This model has improved in the environment of a finite difference software, called FLAC3D. In the formulation of numerical model, the flow and mechanical equations have been solved simultaneously. The 3D model has been calibrated based on the recorded data from the instruments. With using a number valid suggested theoretical and empirical relationships, hydraulic fracturing potential have been calculated and the contour distribution of fracturing pressure at upstream side of the core has been presented. Also, the contour distributions of factor of safety against occurrence hydraulic fracturing phenomenon were determined for all of the suggested relationships at the upstream side of the core. The findings show that, as expected, the steep slopes of valley walls and the difference of the compressibility properties of the core and the shell materials caused significant stress transfer at lower parts of the core and adjacent to the valley walls. Moreover, the values of factors of safety against occurrence hydraulic fracturing phenomenon in upstream side of the core are less than unity near the walls. So, the hydraulic fracturing phenomenon is the one of the main causes initiating the process of internal erosion in the core.

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In this paper, drop weight impact tests using projectiles with different nose shapes on GLARE 3 are examined experimentally. GLARE targets are made of two aluminum sheets and six composite layers by hand lay-up method. The composite layers are constructed using unidirectional E-glass fiber and cy219 resin with adding hy5161 as a hardener. The projectiles are manufactured in flat, hemispherical and conical 90̊ nose shapes and hardened. The projectiles collide to targets with initial impact energies of 40, 55 and 70 Joule. In this study, the effects of nose shape at the maximum impact force, the penetration, the energy absorption, and damage zone are examined. The results show that conical projectile in all three impact energies and hemispherical projectile at 55 and 70 Joule fully penetrate targets. Under impacts of the flat projectile, a shear plug is formed on the upper face of targets and a plastic deformation is created on the bottom face of targets in impact energies of 40 and 55 Joule. For hemispherical projectile at 40 Joule and for flat one at 70 Joule, the tensile stresses in the aluminum sheet located at the bottom face of target result in longitudinal crack. Moreover, results show that the maximum and minimum contact force and energy absorption are occurred in the projectile with flat and conical nose shapes, respectively.

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If in control systems, for any reason, such as cost limitation and environmental conditions, the states of the system could not be measured by measurement sensors, suitable observer should be designed for state estimation. In this paper, a high-gain observer for a class of nonlinear systems in triangular form with divers and simultaneous delay at state, input and output equations is proposed. If time delays are known, sufficient conditions are provided by using Lyapunov-Krasovskii theorem that guarantees the state estimation error converges asymptotically to zero. Conditions are expressed in this way that the output time delay is smaller than the defined amount and also the high-gain parameter in the observer structure is larger than the specified values. Simulation results on inverted pendulum with dc motor control illustrate the effectiveness of the proposed observer.