Utilizing polymeric materials for damping mechanical waves is of great importance in various fields of applications such as military camouflage, prevention of structural vibrational energy transfer, and noise attenuation. This ability originates from segmental dynamics of chain-like polymer molecules. Damping properties of styrene-butadiene rubber containing 10 wt% of monosize polystyrene particles with different diameters (from 80 nm to 500 mm) was investigated in the frequency range of vibration, sound, and ultrasound via dynamic mechanical thermal analysis, normal sound adsorption test, and ultrasound attenuation coefficient measurement. The obtained results indicated that for different systems, containing different sizes of polystyrene particles, the area under the damping curve does not show significant change comparing to the neat SBR in the frequency range studied. However, addition of polystyrene particles, specifically nanosized particles, resulted in emergence of a secondary glass transition temperature which could be attributed to the modified dynamics of a layer of matrix molecules near the surface of PS particles. In the range of sound frequency, 0.5 to 6.3 kHz, the maximum damping was observed for the system containing polystyrene nanoparticles. However the single damping curve of neat SBR was separated into two or even three distinct curves owing to the presence of the particles. The maximum damping in the ultrasound frequency range was found for the system containing 0.5 mm polystyrene particles. This is attributed to different contributions from matrix chains dynamics and the reflection of mechanical waves from particles-matrix interface at different frequency ranges. On other words, the increase in the glass transition temperature of the elastomeric matrix phase with increasing the mechanical wave frequency causes a reduction in the contribution from matrix chains dynamics while the contribution due to diffraction from dispersed phase increases as the particles size approaches the wavelength of the mechanical waves.

Cost and safety are two most important factors involved in the design of civil engineering systems and structures. Thus, the optimal design of structure dimensions is of big importance in order to reduce the cost of construction while meeting the safety requirement and the design constraints. Up to now several algorithms have been developed and used for optimization of different civil engineering problems. One of these algorithms is the Particle Swarm Optimization (PSO) which is a swarm intelligence based algorithm inspired by the social behavior of animals such as fish schooling and bird flocking to solve continuous problems. In this paper, an optimization model is developed for the optimal design of flood control systems which contain both detention dam and bottom outlet. The proposed model uses the powerful PSO algorithm as the search engine and The "Transport Module" of "SWMM" as the hydraulic analyzer of the system. The applicability of the model to solve real world problem is verified by the optimal design of of South Pars flood control system which contains both detention dam and bottom outlet. The results show that the proposed optimization model can considerably reduce the total costs of flood control systems.

Annually, thousands of tons of rubber tires are produced, consumed, and discarded within the country. In recent decades, researchers have investigated the use of rubber fibers or rubber crumbs in concrete and their effects on its mechanical properties. However, the simultaneous utilization of both these materials as substitutes for sand and gravel in concrete has not been thoroughly explored. In this research, this research gap is addressed by examining the results of slump tests on rubber concrete specimens with water-to-cement ratios of 0.45, 0.50, and 0.55, incorporating rubber crumb and rubber fibers up to 25%. The test results indicate a reduction in compressive strength with increasing rubber content. By using different water-to-cement ratios, various rubber concrete proportions, and the SIMAPro software, it was determined that the combination of rubber crumb and rubber fibers leads to approximately a 40% reduction in carbon dioxide emissions in the environment. The optimal condition for all ratios is achieved by adding 4% rubber crumb and rubber fibers.

Increasing population and food demand, disproportionate cultivation and annual production of various agricultural products with market needs and low productivity of the agricultural sector and the loss of water and soil resources have made it necessary to determine and implement the country's optimal cropping pattern. In this study, due to the limitations and problems of classical methods in order to reduce processing time and improve the quality of solutions, the Multi-Objective Chaotic Particle Swarm Optimization was used to determine the optimal cultivation pattern of Sistan plain in optimal conditions and deficit irrigation. The results of the Multi-Objective Chaotic Particle Swarm Optimization for the dominant cultures in the region showed that the current cropping pattern of the region is not optimal and with the implementation of the proposed model, the profit per unit area under cultivation will increase. The results of application of deficit irrigation during different growing periods of wheat, barley, alfalfa, sorghum, watermelon and grapes showed that applying deficit irrigation in this plain is not a good strategy and therefore only a full irrigation strategy is recommended. The results of sensitivity analysis of the model showed that at low prices, farmers reaction is less and at higher prices more reaction to price changes and with increasing prices, the program efficiency is lower.

In this study (Winter, 2007), the changes of histamine content as chemical parameter of spoilage was monitored in the muscle tissue of whole croaker (Otolithes rubber) during ice storage for a period of 18 days (0, 3, 6, 9, 12, 15 and 18th day). Histamine was not detected in the first and 3rd storage days. The first detection of histamine was in the 6th storage day. Initial concentration of histamine was 1.49mg/g and finally reached 14.21 mg/g. Results showed that the concentration of histamine increased linearly (P<0.05) during ice storage (Except day 15). According to the results of this research, the mean concentration of histamine (mg/g) was found less than permissible limits of international standards.

Bitumen in pure form is not suitable for modern roads and present traffic. This has forced engineers to modify bitumen to improve its performance during service life. Two routes are known for bitumen modification, that is chemical and physical modifications. Therefore, there are chemical and physical modifiers. Among physical modifiers, polymers (thermoplastics, rubbers and thermosets) are the most interesting ones. Rubbers are very good bitumen modifiers. In this work non-vulcanized rubbers were incorporated into bitumen. The resulting blends showed better high and intermediate performance compared to the base bitumen. The improved properties are lower penetration and higher softening point. The low temperature properties such as Frass breaking point were not improved. New formulae for estimating bitumen’s performance using the results of conventional Frass and ring and ball tests were introduced. The morphology of the blends, depending on the rheological properties and compatibility of the rubber with bitumen, was different. Polybutadiene formed a continuous phase mixture in bitumen. This was observed due to the compatibility of this rubber with bitumen. Due to lesser compatibility between polymer and bitumen, SBRs and natural rubber formed polymeric inclusion dispersed in bitumen.