Applied Mechanics and Materials Vol. 590

Abstract: This paper presents a predictive investigation using Computational Fluid Dynamic (CFD) techniques focusing on the study of contamination that occurs between different products in an oil pipeline under normal operating conditions. The use of CFD techniques yields detailed flow conditions including the velocity fields, phase distribution and interface evolution, which can provide valuable information to the oil industry especially in the distribution of oil products. The Volume of Fluid (VOF) model is used in this project in a pipe with two fluids. Simulation results show the interface evolution between the two fluids and how it is affected by properties such as viscosity ratio and pressure difference. Operational data from the Nigerian National Petroleum Corporation was obtained to validate the results from the simulations.

Abstract: A system of “master-slave-parallel” chaotic synchronization in class-C lasers is presented. Lasing from a chaotic class-C laser as a master is changed to photon-electricity to drive to modulate the pumps of two parallel of slave class-C lasers so that the two slave lasers can be controlled to the chaotic state of the master laser. “Master-slave” chaotic synchronization can be achieved. At the same time, chaotic synchronization is gradually achieved between the two slave lasers after a few desynchronous oscillations. Lastly, “master-slave-parallel” chaotic synchronization is achieved. Chaotic synchronization process is analyzed in detail. Synchronization principle of the three chaotic lasers is deduced.

Abstract: Because of reservoir heterogeneity around the horizontal section of horizontal well, which makes inflow profile and pressure drop unevenly distributed in horizontal section. It is easy to cause water coning in reservoirs with bottom aquifer and affect the ultimate recovery. With the development of horizontal-well drilling and completion technology, the demand of water control increases step by step. In this paper, we used the node analysis method to establish a wellbore multiphase steady state flow model based on the equivalent filtrational resistance principle, and compared two completions’ water control ability in a case study. Results show that this model can effectively assess the effect of water control in different completion methods, and ICD can give a better water control than slotted liner completion with packer. From our results, we provide a new theoretical reference to a better choice of water-control completion for horizontal wells applications.

Abstract: Using optical microscope, electronic tensile testing machine, scanning electron microscopy methods, such as detailed treatment of the B hypoeutectic Al-Si alloy microstructure, mechanical properties and fracture morphology were studied. The results showed that after treatment by the B refinement, α-Al dendrite phase was refined, resulting in mechanical properties of Al-Si alloy significantly improved. Which, B content 0.036wt.%, the alloy the best, the σb, δ, respectively, than the non-thinning increased 67.8% and 15.2%. From the fracture surface, the fracture morphology of the specimen showed a quasi-cleavage fracture. Which, B content 0.036wt.% at the time of fracture is more deep dimples, and a good plastic toughness.

Abstract: The joint of 2219-T6 aluminum alloy plate was obtained by friction stir welding, and the microstructures and mechanical properties of the joint were investigated. The causes of the weakened joint strength in friction stir welding were analyzed and summarized correspondingly. The tensile properties show that the transverse tensile strength of the joint can reach about 70% of the base metal. Through the heat treatment of recrystallization with high temperature and at short time, the joint can restore the ductility and eliminate the softening, which will improve the performance in mechanical intensity of the joint.

Abstract: This The multi-mode fiber has been widely used in high data traffic applications since the transmitting rate of interface between data storages was larger than the capacity of fiber-optic communication with single mode fiber. The quality of end surface of fiber dominates the data transmitting efficiency. A good cutting end surface of single mode fiber can obtain by the traditional mechanical fiber cleaving methods. But, the multi-mode fiber has much larger core diameter than single mode fiber’s and the quality of cutting end surfaces which cut by the traditional mechanical fiber cleaving methods was not good enough. In the recent year, the pulse CO₂ laser processing methods were introduced to cleave the fibers. In this research, a glass fiber laser cutting system was developed. The shapes of laser focusing spot and the concepts of laser cutting optical design were discussed in this paper. The experimental results show that the fiber cutting end surfaces with great quality, which were inspection by interferometer, can be obtained by the developed laser cutting system.

Abstract: The result of direct ablation of silicon by an 800 nm Ti:Sa femtosecond laser pulses are presented. The minimum size of the crater on the silica surface ~ 250 nm was obtained, and in the central region of this crater can be identified about 170 nm in depth. In the ablation mode by single pulses received ordered structure with a length of ~ 230 nm and width of ~ 1.8 um and a period of ~ 1 um. Increasing the number of pulses without changing the focus position leads to complex and heterogeneous structure of modifications of silicon.

Abstract: In this study, experiments were performed to study the effects of electrode materials mixed with nickel in electrical discharge machining (EDM) of SUS 304 material. Experiments were constructed using parameters consisting of pulse-on time, pulse-off time, discharge current and electrode polarity, respectively. The analysis of structural features of the surface was accomplished using a scanning electron microscope (SEM) as well as an element analysis created on the surface, after the EDM process, by using Energy-dispersive x-ray spectroscopy (EDS). The results of the experiments found that nickel elements in the electrode material have an effect on the working performance of material removal rate and electrode wear ratio. The electrode wear ratio reduces when nickel elements increase. Moreover, the surface roughness had the lowest level at electrode 15 % nickel element. Thus, electrode wear during the EDM process of nickel element from electrodes and other elements, combined with surface metalworking, becomes a recast layer of nickel.

Abstract: The nanocomposites of carbon nanotube/polymer have been studied to explore their piezoresistance properties, which can be used as smart materials in the fields like biomedical engineering, robotic engineering, and advanced instrumentation. The differences in piezoresistance behavior of the previous studies were explained by the less uniformity of carbon nanotubes. To clarify the resistance versus deformation relations for carbon nanotube/silicone rubber composite materials, we have fabricated composite materials with various nanotube and carbon black contents. The measurements show that the resistance versus deformation sensitive range is depends on both the content of nanotube and carbon black, while the tiny variation of content of the carbon black affects largely the total piezoresistance sensitivity and repeatability. The experiment shows that adequate amount of carbon balck mixed with carbon nanotube can improve the piezoresistance repeatability. The deformation induced variation of the conducting percolation network shall be the dominating mechanism for the piezoresistance behavior of carbon nanotube/silicone rubber composites.

Abstract: Arc-discharged single-walled carbon nanotubes were purified by successive heating in the air, hydrochloric acid treatment, supersonic dispersion in aqueous sodium deoxycholic acid solution, and high-speed centrifugation. Scanning electron microscopy observation evidenced that amorphous carbon, metal/metal oxide nanoparticles, and non-tube carbon impurities are separated from single-walled carbon nanotubes step by step. The relative carbonaceous purity of the purified single-walled carbon nanotubes to the as-produced materials was estimated to be ~7.42 by solution/dispersion-phase near-IR spectroscopy.