The birefringence and anisotropic planar shrinkage of polycarbonate/organoclay injection moldings

The main objective of the present work was the study of the effect of organoclay on planar shrinkage anisotropy of polymeric injection‐molded products by means of a rheological technique, in conjunction with birefringence measurements, performed on polycarbonate/organoclay samples. Polarized optical microscopy at elevated temperatures revealed that the birefringence due to the ordered‐silicate layers had a negative contribution to the overall birefringence of the samples. The maximum value of the calculated‐order parameter based on these results was found to be near unity, indicating an appreciable degree of flow alignment for the silicate layers. Different states of silicate layer orientation, with some layers aligned parallel to the in‐plane direction at the skin layer or partially tilted from the planar direction at the core region, were observed through the optical analysis along the thickness direction. The anisotropic shrinkage measurements showed that organoclay reduced both in‐flow and cross‐flow shrinkages, resulting in a low extent of planar shrinkage anisotropy. This can be attributed to the flow alignment of clay particles closely parallel to the in‐plane direction. Prolonged relaxation of the flow‐induced molecular orientation combined with faster solidification were also found to play an appreciable role in the decreased shrinkage anisotropy. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

An efficient method for impulse noise reduction from images using fuzzy cellular automata

Impulse noise reduction from corrupted images plays an important role in image processing. This problem will also affect on image segmentation, object detection, edge detection, compression, etc. Generally, median filters or nonlinear filters have been used for noise reduction but these methods will destroy the natural texture and important information in the image like the edges. In this paper, to eliminate impulse noises from noisy images, we used a hybrid method based on cellular automata (CA) and fuzzy logic called Fuzzy Cellular Automata (FCA) in two steps. In the first step, based on statistical information, noisy pixels are detected by CA; then using this information, the noisy pixel will change by FCA. Regularly, CA is used for systems with simple components where the behavior of each component will be defined and updated based on its neighbors. The proposed hybrid method is characterized as simple, robust and parallel which keeps the important details of the image effectively. The proposed approach has been performed on well-known gray scale test images and compared with other conventional and famous algorithms, is more effective.     

The effect of natural antioxidants extracted from plant and animal resources on the oxidative stability of soybean oil

The objective of this study was to evaluate and compare the antioxidant activity of protein hydrolyzates isolate (PHI) from Crucian carp (Carassius carassius) fish and cow's intestine along with microwave-assisted olive leaf extract (OLE) encapsulated by Arabic gum and maltodextrin, in soybean oil. The antioxidant activity of PHIs at three concentrations of 200, 500 and 1000 mg/kg and OLE samples containing 70 mg/kg total phenolics during 20 days storage was evaluated by peroxide value, TBA value, p-anisidine value and Rancimat stability test. The fish PHI at concentration of 1000 mg/kg, cow's intestine PHI at 500 and 1000 mg/kg and OLE encapsulated with Arabic gum showed best oxidative protection activity (more than BHT at 100 and 200 mg/kg). OLE had a suitable antioxidant activity in soybean oil and encapsulation improved the thermal stability of phenolic compounds, but on the other hand, it decreased the antioxidant efficiency of OLE.     

Estimation of lung's air volume and its variations throughout respiratory CT image sequences

A respiratory image-sequence-segmentation technique is introduced based on a novel image-sequence analysis. The proposed technique is capable of segmenting the lung's air and its soft tissues followed by estimating the lung's air volume and its variations throughout the image sequence. Accurate estimation of these two parameters is very important in many applications related to lung disease diagnosis and treatment systems (e.g., brachytherapy), where the parameters are either the variables of interest themselves or are dependent/independent variables. The concept of the proposed technique involves using the image sequence's combined histogram to obtain a reasonable initial guess for the lung's air segmentation thresholds. This is followed by an optimization process to find the optimum threshold values that best satisfy the lung's air mass conservation and tissue incompressibility principles. These threshold values are consequently applied to estimate the lung's air volume and its variations throughout respiratory Computed Tomography (CT) image sequences. Ex vivo experiments were conducted on porcine left lungs in order to demonstrate the performance of the proposed technique. The proposed method was initially validated using a breath-hold CT image sequence with known air volumes inside the lung, where results show that the proposed technique outperforms single-histogram-based methods. This was followed by demonstrating the proposed technique's application in a 4-D-CT respiratory sequence, where the air volume inside the lung was unknown. Consistency of the obtained results in the latter experiment with tissue near incompressibility principle was validated. The results indicate a very good ability of the proposed method for estimating the lung's air volume and its variations in a respiratory image sequence.     

Nuclear model calculations on the production of Sb via various nuclear reactions

Only very few radionuclides exist that decay exclusively by EC-mode without accompanying radiation, ¹¹⁹Sb is one of them. Auger emitter ¹¹⁹Sb (T_1/2 = 38.9 h, I_EC = 100%) is a potent nuclide for targeted radionuclide therapy based on theoretical dosimetry calculations at a subcellular scale. Auger electron emitting radionuclides in cancer therapy offer the opportunity to deliver a high radiation dose to the tumor cells with high radiotoxicity while minimizing toxicity to normal tissue.     

Dye removal from colored‐textile wastewater using chitosan‐PPI dendrimer hybrid as a biopolymer: Optimization,kinetic, and isotherm studies

Preparation of a biopolymer chitosan‐polypropylene imine (CS‐PPI) as a biocompatible adsorbent and its reactive textile dyes removal potential were performed. Chemical specifications of CS‐PPI were determined using Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR. The surface morphology of the CS‐PPI surface was characterized by scanning electron microscopy. Results confirmed that the linkages between the NH₂ groups of PPI dendrimer and carboxylic groups of modified Chitosan were accomplished chemically. Two textile reactive dyes, reactive black 5 (RB5) and reactive red 198 (RR198), were used as model compounds. A response surface methodology was applied to estimate the simple and combined effects of the operating variables, including pH, dye concentration, time contact, and temperature. Under the optimal values of process parameters, the dye removal performance of 97 and 99% was achieved for RB5 and RR198, respectively. Furthermore, the isotherm and kinetic models of dyes adsorption were performed. Adsorption data represented that both examined dye followed the Langmuir isotherm. The adsorption kinetics of both reactive dyes were satisfied by pseudo‐second order equation. Based on this study, CS‐PPI due to having high adsorption capacity (6250 mg/g for RB5 and 5882.35 mg/g for RR198), biocompatibility and ecofriendly properties might be a suitable adsorbent for removal of reactive dyes from colored solutions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Texture Evolution and Twinning During the Expansion of Hot Extruded AZ31 + Sr Seamless Tubes

Seamless tubes of AZ31, AZ31 + 0.4, and 0.8 wt pctSr were extruded at elevated temperatures. By compressing pure copper inserts inside the tubes, the extruded tubes were expanded at room and elevated temperatures [373 K and 473 K (100 °C and 200 °C)]. Microstructural examinations reveal the formation of twining in the as-extruded and expanded tubes. The amount of twinning decreased with increasing level of Sr in the expanded microstructures as a result of grain refinement and of decreasing Al in solution that facilitates dislocation motion. During expansion at room temperature, AZ31 shows higher elongation and lower strength than the alloys containing Sr. At 473 K (200 °C), compared to the lower temperatures, the Sr containing alloys exhibit lower flow stress and no fracture in the strain range investigated (40 pct reduction in cylinder height). The textures of the extruded alloys contain two main components named as RD (c-axis parallel to the radial direction) and HD (c-axis parallel to the hoop direction) based on their orientation with the sample coordinates. During expansion, extension twinning in the HD grains reorients the lattice to strengthen the RD and form a new ED (c-axis parallel to the extrusion direction) component. By increasing the temperature or level of Sr, the ED component is weakened due to the decrease in twinning. During expansion, the RD grains undergo contraction and double twining which reduce the overall texture strength.     

Flow Visualization in a Pocketed Thrust Washer

The objectives of this study were to experimentally and numerically investigate oil flow in surface-pocketed thrust washers. In order to achieve the experimental aspects of this investigation, a thrust washer test rig was designed and developed to visualize the lubricant flow at the contact interface. A novel approach for creating the pockets was developed to allow optical inspection of the lubricant during thrust washer operation. The thrust washers were fabricated using a glass disk with a thin layer of steel shim stock adhered to the surface. The micrometer-thick shim stock was machined using an Nd:YAG laser to create the circular pocket geometries and then glued to the glass disk. A mirror and camera were placed below the semitransparent washer to observe the lubricant flow in the pocket. The results obtained from this configuration illustrate a cavitation bubble forming on the leading edge of the pocket followed by a sharp transition back to liquid. The size of the cavitation area was found to be a function of rotational speed, nominal bearing pressure (NBP), viscosity, and pocket geometry. The cavitation area ratio (gaseous region divided by the pocket area) increased for greater speeds and higher viscosities and decreased for larger pocket diameters, deeper pockets, and higher NBPs. The friction force for various thrust washer designs was also measured as a function of load, speed, and lubricant. The results showed that shallower, wider pockets provided the lowest friction. It was found that, generally, the conditions that minimize friction also result in a stable cavitation region. ANSYS Fluent computational fluid dynamics software was used to develop a three-dimensional model of the pocketed thrust washer utilizing the full Navier-Stokes equations to investigate the cavitation and pressure distribution occurring at the contact and corroborate the experimental results.     

An Improved Approach for 3D Rolling Contact Fatigue Simulations with Microstructure Topology

Several 2D and 3D numerical models have been developed to investigate rolling contact fatigue (RCF) by employing a continuum damage mechanics approach coupled with an explicit representation of microstructure topology. However, the previous 3D models require significant computational effort compared to 2D models. This work presents a new approach wherein efficient computational strategies are implemented to accelerate the 3D RCF simulation. In order to reduce computational time, only the volume that is critically stressed during a rolling pass is modeled with an explicit representation of microstructure topology. Furthermore, discontinuities in the subsurface stress calculation in the previously developed models for line and circular contact loading are removed. Additionally, by incorporating a new integration algorithm for damage growth, the fatigue damage simulations under line contact are accelerated by a factor of nearly 13. The variation in fatigue lives and progression of simulated fatigue spalling under line contact obtained using the new model were similar to the previous model predictions and consistent with empirical observations. The model was then extended to incorporate elastic–plastic material behavior and used to investigate the effect of material plasticity on subsurface stress distribution and shear stress–strain behavior during repeated rolling Hertzian line contact. It is demonstrated that the computational improvements for reduced solution time and enhanced accuracy are indispensable in order to conduct investigations on the effects of advanced material behavior on RCF, such as plasticity.     

A fuzzy grey goal programming approach for aggregate production planning

Aggregate planning is a medium-range capacity planning that suggests the production strategies in order to meet the forecasted demand considering the capacity constraints. As the period of planning length increases, the uncertainty of information will grow. Regarding this point, in this paper, a multi-objective model is proposed for aggregate planning problem in which the parameters of the model are expressed in the form of grey numbers. The suggested grey multi-objective model is solved based on a goal programming problem with fuzzy aspiration levels. The model is applied in a real-world problem, and its results are illustrated. The obtained results give a range for decision variables, and decision makers can handle the inevitable uncertainty of information by using these ranges.