Climate Change and Its Impact on Brown Bear Distribution in Iran

Climate change is one of the threats in the recent century, affecting biodiversity directly and indirectly. Modeling the patterns of species distribution is one of useful tools for predicting the impacts of climate change on endangered species. Brown bear (Ursus arctos) plays an important role as a focal species in mountainous ecosystems. This study was aims to investigate the effects of future climate changes on the distribution of this species using an ensemble modeling method in R-software. For this purpose five algorithms including MAXENT, RF, MARS, GAM, GLM and BRT were used to predict the distribution of the species in the present climatic conditions as well as in the 2050s and 2070s. The results showed that temperature and precipitation were two main factors in the distribution of brown bears in Iran. Investigating the distribution of the brown bear in the future showed that suitability of its habitat will decrease in the western and central parts and increase in the northern parts. So a shift toward higher altitude will be expected for brown bear in the future. Therefore, in this condition it is imperative to upgrade the extent of protected areas for better conservation of brown bear

Time-Dependent Hazardous-Materials Network Design Problem

We extend the hazardous-materials (hazmat) network design problem to account for the time-dependent road closure as a policy tool to reduce hazmat transport risk by altering carriers’ departure times and route choices. We formulate the time-dependent network design problem using an alternative-based model with each alternative representing a combined path and departure-time choice. We also present an extended model that can not only account for consecutive time-based road closure policies but also allow stopping at the intermediate nodes of the network in the routing/scheduling decisions of the carriers. Heuristic algorithms based on column generation and label setting are presented. To illustrate the advantages that can be gained through the use of our methodology, we present results from numerical experiments based on a transportation network from Buffalo, New York. To investigate the impact of the extensions, we consider three versions of the problem by gradually refining the model. We show that under consideration of extensions, the design policies are more applicable and effective

Time-Dependent Hazardous-Materials Network Design Problem

We extend the hazardous-materials (hazmat) network design problem to account for the time-dependent road closure as a policy tool to reduce hazmat transport risk by altering carriers’ departure times and route choices. We formulate the time-dependent network design problem using an alternative-based model with each alternative representing a combined path and departure-time choice. We also present an extended model that can not only account for consecutive time-based road closure policies but also allow stopping at the intermediate nodes of the network in the routing/scheduling decisions of the carriers. Heuristic algorithms based on column generation and label setting are presented. To illustrate the advantages that can be gained through the use of our methodology, we present results from numerical experiments based on a transportation network from Buffalo, New York. To investigate the impact of the extensions, we consider three versions of the problem by gradually refining the model. We show that under consideration of extensions, the design policies are more applicable and effective

Regulating Hazardous Materials Transportation by Dual Toll Pricing

We investigate dual-toll setting as a policy tool to mitigate the risk of hazardous material (hazmat) shipment in road networks. We formulate the dual-toll problem as a bi-level program wherein the upper level aims at minimizing the risk, and the lower level explores the user equilibrium decision of the regular vehicles and hazmat carriers given the toll. When the upper level objective is to minimize the risk and all links are tollable, we decompose the formulation into first-stage and second-stage, and suggest a computational method to solve each stage. Our two-stage solution methodology guarantees nonnegative valid dual tolls regardless of the solution accuracy of the first-stage problem. We also consider a general dual-toll setting problem where the regulator rather wishes to minimize a combination of risk and the paid tolls and/or some links are untollable. To solve this truly bilevel problem, we provide heuristic algorithms that decompose the problem into subproblems each being solved by a line search. Case studies based on the Sioux Falls network illustrate the insights on the dual-toll policies

Investigation of the Effect of Internal Mold Release Agent and Filler on the Pulling Force in Pultrusion Process

Pulling force is one of the most important variables in pultrusion process which determines the capacity of the pultrusion machine. One of the characteristics of a desired pultrusion process is a low pulling force and a high line speed.Among the important factors affecting the pulling force are the internal mold release agent (IMR) and the content and particle size of the filler in resin formulation. In addition to facilitating the part separation from the die, IMR also affects the curing kinetics and in turn the pulling force. In this research, a commercial IMR has been used in a range 1-5 phr. DSC and DMTAAnalyses showed that the presence of IMR in concentrations above 3 phr reduces the heat of curing reaction and also the curing rate. This results in an increase in pulling force. Study of filler effect showed that the increase in filler content from 4 to 8 phr reduces the pulling force but beyond that it is increased. Also, decreasing the filler particle size in line speed lower than 30 cm/min reduces the pulling force but increases it at higher line speed

Surface Modification of Silica Nanoparticles with Titanium Tetraisopropoxide and Evaluation of their Photocatalytic Activity

Silica nanoparticles were modified with titanium tetraisopropoxide (TTIP) via atwo-step sol-gel route. The modified silica nanoparticles were characterized using FTIR spectroscopy, thermal gravimetric analysis (TGA) and EDAX elemental analysis. Photocatalytic activity of the modified nanocomposites was evaluated by photo-activated degradation of Rhodamine B (Rh.B) dyestuff, as a colorant model, in distilled water. Reduction in Rh.B concentration in aqueous solution was evaluated by UV-visible spectroscopy and with the aid of visual observations. The FTIR spectroscopy results confirmed the formation of Ti-O-Si chemical bond on the surfaceof silica nanoparticles. TGA test results showed that the weight loss of the modified sample is due to deterioration of the alkoxy groups of the SiO2 surface. According to the results of EDAX elemental analysis, the presence of carbon and titanium in the structure of the modified samples and also reduction in oxygen levels are attributed to the chemical interactions due to surface chemical modification. Carbon detection in the composition can be attributed to the presence of isopropoxide in titanium tetraisopropoxide compound. The results also revealed that, with TiO2 grafting on the silica nanoparticles surface, absorption in UV region is increased and that the silica nanoparticles modified with titanate compound show photocatalytic characteristics and degradation ability of Rh.B dyestuff under UV light irradiation. It became also evident that the photocatalytic activity of the modified nanoparticles is less than TiO2 nanoparticles. However, by inclusion of modified silica nanoparticles into the polymeric coating, the photocatalytic properties of the coating can be established. Although modified silica nanoparticles have less photocatalytic activity compared to TiO2 nanoparticles, but they cause less damage to the polymer matrix

Surface treatment of TiO2nanoparticles via sol–gel method: effect of silane type on hydrophobicity of the nanoparticles

Hydrophobic TiO nanoparticles are important elements in preparation of functional organic coatings. In fact, hydrophobicity of the nanoparticle helps to optimize the photoactivity of the coating while maintaining its durability. In this study, surface treatment of the commercial TiO nanoparticles was carried out using various silane precursors via sol-gel method in both acidic (pH 2) and alkaline media (pH 12). A long aliphatic chain (F1), a short aliphatic chain (F2), and an aromatic (F3) fluorosilane were used for this purpose. The treated nanoparticles were characterized using Fourier transform infrared and X-ray photoelectron spectroscopy, thermal gravimetric analysis, and transmission electron microscopy. Hydrophobicity of the treated nanoparticles was evaluated by floating in de-ionized water. The results showed that the adsorption of F1 on TiO only takes place in the alkaline condition while F3 is adsorbed in both alkaline and acidic conditions. Furthermore, no significant adsorption for F2 was detected neither in alkaline nor acidic conditions. The floatation results revealed a hydrophobic nature for F1 and F3 treated nanoparticles, however, nanoparticles attempted with F2, remained hydrophilic. It was concluded that the hydrophobicity of the nanoparticles is affected by both chemical nature of fluorosilane as well as pH of the treatment media

Flame Retardant Hybrid System of Triphenyl Phosphate/Nanoclay in Evaluation of Flammability and Mechanical Properties of PC/ABS Compound

Nanoclay/triphenyl phosphate hybrid system was employed to examine the fire retardancy and mechanical properties of PC/ABS blends. Each of the polymers and their blends are widely used in the automotive, electrical andelectronic industries. Because most thermoplastics are easily combustible they need to be flame retarded to reduce the burning rate especially in the initial phase of a fire incident. The effect of nanoclay on the fire resistance of nanocomposites has been the subject of many research works. Nanosize clay particles improve the fire performance of composites with no significant effect on the ignition ability and extinguishing time. The improvement in flame retardancy of composites has been observed only when nano size species are present with conventional flame retardant additives. Such combinations may result in either a desired level of flame retardancy lower than the normal conventional level with matrix property retention. In this study, the samples were prepared via a direct melt blending process in a twin-screw extruder, and the processing temperature was set at 200-250oC. The effects of nanoclay/triphenyl phosphate hybrid system on the fire retardancy of PC/ABS blend were assessed by cone calorimetry, LOI (Limited Oxygen Index) and UL94 (Underwriters Laboratories), and tensile and impact properties of the composites were determined. The synergistic effect of nanoclay on flame retardancy of TPP has been observed from the fire test and the mechanical properties were improved

Development of Braiding-Pultrusion Method and Investigation of Mechanical Properties of Composite Rods Produced by this Method

In this research, a braiding-pultrusion production line is developed by modifying a conventional textile maypole braiding machine and adding it to a pultrusion line for production of braid-pultruded (BP) composite rods. In order to evaluate the mechanical properties of BP rods and study the effect of some braiding parameters, they were produced with different braid roving linear densities and braid angles. The results are also compared to those of unidirectional (UD) pultruded rods which were produced without braided fabric cover, but with the same fiber volume fraction and diameter.The results showed BP rods had higher shear modulus, but lower tensile modulus and flexural rigidity compared to UD rods. It was also concluded that increasing the braid roving linear density leads to an improvement in shear modulus, but a reduction in tensile modulus and flexural rigidity. Moreover, the highest shear modulus is observed in the rod with braid angle of 45o. Tensile modulus and flexural rigidity decrease when braid angle increases