فهرست مطالب وحید مومنی

In this research, the effect of adding clay Nanoparticles on increasing the lifetime of glass/epoxy composites under hydrothermal conditions has been investigated. For this purpose, samples containing 3 Vol.% of clay Nanoparticles and samples without clay Nanoparticles in resin epoxy has been manufactured for the fabrication of specimens of the tensile test using hand lay-up and vacuum bag. The specimens were placed under the hydrothermal condition of 90% humidity and 75 °C temperature for 500 hours in the incubator and were tested for tensile properties. The results show that addition of clay Nanoparticles decreases the strength of the composite by 21.39% in the newly produced samples while in a long time, these particles slow down the process of composite degradation, so that in the same environmental conditions, the strength of specimens containing clay Nanoparticles is 9% higher than the specimens without clay Nanoparticles.

Metal injection molding (MIM) is a novel process classified in powder metallurgy. This process can produce complex metallic parts with high rate of production and consists of four stages, including mixing, injection, debinding, and sintering, where the properties of the final part highly depends on the parameters of each of these stages. In this study, the parameters of injection pressure, injection and mold temperature, holding pressure, holding time, injection speed, and cooling time on the density, strength, and hardness of the final MIM compact have been investigated. By the design of experiments and response surface methodology (RSM) method, 50 samples have been injected using different parameters. In order to measure the density, tensile strength, ad hardness of the samples, the debinding and sintering procedures have been done on the injected samples. The results show that the injection pressure, injection temperature, and mold temperature have the highest effect on the strength and density of the final part, respectively, and on the other hand, holding pressure, holding time, and cooling time have a negligible effect. Within the measured properties, density and strength are more affected by the injection parameters compared to hardness. Finally, the optimum injection parameters for samples made of 4605 low alloy steel include injection pressure of 133 bar, injection temperature of 158, mold temperature of 60, the holding pressure of 70 bar, holding time of 8 second, injection speed of 112 mm/min, and cooling cycle of 17 second.

The main purpose of this paper is to the distributed formation tracking for fractional order multi agent systems with the leader-follower approach. First, it discusses the Lyapunov candidate function used to check the stability of the controlled system. The introduced candidate function is based on the properties of the matrix representing the desired system graph of the system. In this phase, the Lyapunov direct method is used to determine the stability of fractional order systems. Then, using sliding mode control, a decentralized controller design for tracking in fractional multi agent systems is presented in which it introduces and verifies the introduced control inputs. In the model, the input system is also considered as a disturbance type, and the control efficiency designed in turbulence mode is shown. In this section, it is shown that the controller introduced in the previous section has a desirable efficiency due to the sliding mode control. In the second section, the stability of the system, such as the first section, is investigated. at the end of this paper, several simulation examples are developed for controlling the performance of the controller.

Biofouling is a process in which microorganisms grow and proliferate on the surface. Biofouling is a problem made by biofilm. This kind of fouling occurs in a wide range of industrial process and causes problems for the high-priced process, in particular. In different industries, it has been worked out to deal with this issue, separately. In all of them, the main problem is the biofilm formation. These days, many marine autonomous environment monitoring networks are set up in the world. Owing to the intense technological development of in situ autonomous monitoring systems, the biofouling problem for such systems has been a technological one which needed to be solved. Consequently, such systems without efficient biofouling protection are hopeless. Localized electro-chlorination biofouling protection is actually a promising and an advanced solution for in situ oceanographic sensors since many successful in situ results have been obtained and sensor manufacturers can integrate into their instruments a compact, simple, robust and low energy requiring a solution. This protection must be applied to the sensors and to the underwater communication equipment based on acoustic technologies. This paper presents the results obtained in the laboratory and at sea, with various instruments, protected by a localized chlorine generation system.