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Vol 2 No 2 (2020)

  • The Preparation of Coal based Graphene and It’s Application in the Field of Thermal Conductivity

    Wen-Wei Ma

    Graphene is a new material with good physical properties and high added value. Coal can be made into model compounds by different physical and chemical methods to realize the efficient utilization of coal, so that new coal based materials with high added value can be formed. Based on this, in the process of research and analysis, the preparation of coal based graphene and its application in the field of thermal conductivity were studied. Based on the lateral guiding excitation of graphene, its performance and application of thermal conductivity are analyzed comprehensively. On the basis of external force control, it has a positive effect on improving the thermal conductivity of graphene composites.

  • Study of High Temperature Crack Initiation and Growth in Light Capturing Ribbon (LCR) PV Module Interconnection

    Alireza Eslami Majd, Nduka Nnamdi Ekere

    The ribbon interconnection between solar cells (used for collecting current from solar cells) is a key PV module component and it highly affects the reliability of PV module as interconnection failure can lead to PV module performance. Light Capturing Ribbon (LCR) is a new type of interconnection to increase the efficiency of PV modules by reflecting the incident sun rays from the interconnection ribbon to the cell surface. This paper studies a comparison of the crack initiation and growth in the PV module interconnection due to the high-temperature manufacturing process between Light Capturing Ribbon (LCR) and Conventional Ribbon (CR). Extended Finite Element Method (XFEM) in ABAQUS software is employed to find the Crack Initiation Temperatures (CIT) and the Crack Growth Rate (CGR) for different configurations of PV module interconnection designs. The optimum solder, silver, and copper thickness for LCR interconnection are recognized as 20µm, 40µm, and 125-187.5µm, respectively, where this configuration experiences smaller cracks in the solder joint material rather than CR interconnection with the same cross-section area.

  • Investigation on the Pulsed TIG Welding of Nickel-Base Alloy for Improved Microstructure and Weld Penetration

    Dayou Pan, Yijun Man

    In this study, a novel pulsed tungsten inert gas (TIG) welding technique that is capable of effectively improving the weldabilities of nickel-based alloys was developed.  The correlation between process parameters and material properties was studied. The effects of ratios of pulse to background welding currents on hardness and penetration in welds and heat-affected zones (HAZs) of Inconel 718 alloy were investigated experimentally by using the pulsed TIG welding technique. It is found that with an increasing ratio of the pulse to background welding current, the hardness in welds increased from 2% to 3.5%, compared to that in constant current TIG welding at the same level of heat input. When the ratio of pulse to background welding current is higher than 6, the penetration in weld was improved significantly by up to 61%. Research work has demonstrated that the pulsed TIG welding technique is an effective approach to control the microstructure and reduce cracking susceptibilities.

  • Study on Degradation Law and Related Mechanism of Mechanical Properties of Internal Reinforcement of RC Bridge After Uneven Corrosion

    Hong-Yu Lu, Man Zhou, Bao-Hong Hao, Jian-Yu Pan, Ding Zeng

    In order to explore the corrosion process of the internal reinforcement of the bridge under the actual working conditions. In this paper, the accelerated stress corrosion test of HRB400e steel bar was carried out by full immersion method in laboratory, and the constant tensile stress was applied to the experimental steel bar in the form of constant moment beam specimen. After the test, the mechanical properties and microstructure of the steel bar were tested, and the experimental model was analyzed by finite element simulation. The experimental results show that with the increase of load, the corrosion degree of reinforcement increases gradually, and the number of pitting holes increases obviously. Microcracks lead to transgranular failure of metal lattice, which makes the microstructure more loose. The mechanical properties of steel bar have different degrees of degradation after rust, and the degradation of elongation is the most obvious. The results of finite element simulation are similar to the actual experiment, and there are obvious pitting pits at the stress concentration.

  • Nano-refraction Analysis for Advanced Materials: A Theoretical Roadmap for Quantum Computers

    Hassan Kaatuzian

    We are now in the beginning of quantum supremacy to build Quantum Computers (Q.C.). So, a theoretical roadmap is required. It seems experimental works in Q.C. is ahead, in comparison with theory. In this study, Nano-Refraction (N.R.), as basic concept in developing Quantum Photonic Computers (Q.P.C.), is defined and discussed. N.R., is quite different from classical macroscopic refraction. It plays major role in photon deflection, when it travels in few atomic layers from the boundary between two transparent materials. Specifically, when we’re looking for a theoretically intuitive explanation of how advanced materials work in atomic scales in atto-second regime. To explain N.R., mathematically, Quantum Electrodynamics (QED) may help. But QED, only can describe how N.R. occurs in Hilbert space and does not explain why it happens in Real space? Why attosecond optical pulses are squeezed in kilometers long optical fibers coiled in first reported development of Q.C. in 2020. Also, “Duality” has no reply in this area. For answering why?, in this paper, we’ll use Quantum Photonic (Q.P.) theoretical analysis. Q.P., is based on Bohmian mechanics with intuition physics belief and “Causality”. Bohm theory in shadow of Quantum Mechanics (Q.M.) has been mostly ignored and even boycotted during last 70 years. Q.P. corpuscular viewpoint of light, estimated both physically and mathematically with enough precision, that flight route of photons at first few molecular surfaces in boundary region is not refracted suddenly. As can be observed macroscopically in Snell’s refraction equation. But instead, N.R. is happened gradually in attosecond regime (figure 2). Finally, it asymptotes to macroscopic refraction, in large space-time scales according to “correspondence” principle. Errors in our theoretical analysis using Montecarlo time domain simulation, compared with experiments, always are much less than or at most five percent.