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Sustained increase in plastic use has placed a significant burden on waste disposal infrastructure. Pyrolysis is the process of decomposing high-molecular-weight compounds by heating waste plastics at 500–1000 °C without oxygen. This process considerably reduces greenhouse gas emissions and has a high alternative energy effect (0.57 TOE ton−1). After a separation process, the oil produced by pyrolysis (C5–C20) can yield naphtha oil (C6–C7). Subsequently, hydrogen can be produced through a reforming reaction of this naphtha oil. Here, we produced hydrogen from waste plastic pyrolysis oil over a Ni/Ce-Zr-Mg/Al2O3 catalyst using a steam reforming process. A model oil combining the major substances of C6 and C7 (hexane, hexene, heptane, heptene, and toluene) was formed. From the reaction products, the hydrogen yield was obtained based on analysis of H2, CO, and CO2 concentrations using gas chromatography. The effect of N2 and O2 addition on hydrogen yield was analyzed within a temperature range of 750–850 °C, steam/carbon (S/C) ratio of 0.6–4, and space velocity of 7600–19,100 h−1. In addition, a durability test was performed using 3 wt.% Ni/Ce-Zr-Mg/Al2O3 catalysts for 100 h; a hydrogen yield of 91.3% was maintained from the refined waste plastic oil.

In this study, a flexible conductive filament was fabricated by mixing thermoplastic polyurethane (TPU), carbon nanotubes (CNTs), and Cu powder. A polymer extruder was used to disperse conductive materials in the TPU matrix. Because the dispersion of CNTs in polymers is difficult, the dispersion process was repeated several times for the homogeneity of the fabricated conductive filament. Cu powder with high electrical conductivity was additionally added to improve the electrical characteristics of the conductive polymer. As TPU generally has excellent ductility and durability, the fabricated filament can secure flexibility. The resistance was measured and compared according to the mixing ratio of CNT/Cu powder. Based on the obtained results, the resistance of the conductive filament decreased as the CNT and Cu powder contents were increased. The addition of metal powders, such as CNTs and Cu powder, however, reduced the ductility of TPU. Finally, the developed conductive filament was used to fabricate a simple closed photodiode circuit.

The experiments of wire arc additive manufacturing (WAAM) with general pulsed gas metal arc welding (GMAW) machine were performed to optimize process parameters. As optimized conditions, 140A welding current, 34 V welding voltage, 40 cm/min welding speed, and 15 mm contact tip to work distance (CTWD), were selected. Welding current and voltage affected heat input. Lower deposition, short circuit mode, and spatters were obtained by insufficient heat input. The melting of previous layer and lower height were obtained by excessive heat input. Welding speed and CTWD affected surface state and arc stability. Unsound surface and bead shape due to short circuit mode and spatters were observed in slow welding speed and short CTWD conditions. Arc instability were also observed in fast welding speed and long CTWD conditions. With the optimized process parameter, curved propeller shape blade was manufactured by the change of robot arm teaching point. It can be considered that the desired sufficient quality was obtained due to curved shape.

Several studies have been conducted to predict issues caused by the welding process. The finite element method is extremely useful in analysing this welding process. Generally, in the analysis of welded structures, the welded joint is assumed to be rigid to large structure on vehicle-body crash or fatigue. This assumption does not require a theoretical background of a complicated welding process; therefore, it is relatively easy to set up an analysis model, which significantly reduces the analysis time. However, material properties and mechanical behavior of welded structures cannot be expressed, and there is no sufficient verification for this in several industries. Moreover, few studies have reported on strength analysis, including the welding process; therefore, this study presents a simple modeling using commercial program based on the finite element method. The welding process is simulated by identifying the welding-heat-source variable through experiments and a value close to the measured deposited metal and fusion-zone size are obtained. A flow stress–strain curve based on a uniaxial tensile test is obtained and the tensile strength of the welded specimen is analyzed.

Homogeneous and heterogeneous PAW (plasma arc welding) experiments were conducted to obtain weld beads with tensile strength of 100% or more compared to that of the base metal in lap joint fillet welding of CP (complex phase) 780 MPa grade high strength steel sheet. Homogeneous and heterogeneous welding mean welding technic without and with welding wire in each. Common basic welding parameters of both homogeneous and heterogeneous PAW wire were applied, including welding speed of 21 cm/min, arc length of 3.5 mm, weaving amplitude of 3 mm, work angle of 30°, and Ar 99.99% shielding gas with 12 L/min. In homogeneous PAW, the optimized additional welding conditions were a welding current of 90 and 95 A, push angle of 20°, and weaving frequency of 5 Hz. The fracture strengths of all the samples were less than that of the base metal, and all fractures occurred at the weld bead fusion zone due to insufficient reinforcement. In heterogeneous PAW, the optimized additional welding conditions were a welding current of 125 A, push angle of 0°, weaving frequency of 4 Hz, and wire feed speeds of 1.53 and 1.38 m/min. Moreover, the welding wire was fed from behind the arc. The fracture strengths of all the samples were greater than that of the base metal, and fractures occurred at the base metal or fusion zone boundary. The reason for higher tensile in heterogeneous PAW wire is deduced as the large cross-section area of reinforcement provided by the welding wire comparing to homogeneous welding. It is well known that small radius of welding heat source clearly produces narrow heat affected zone. Therefore, the PAW produces relatively narrower heat affected zone, then resulted as fully enough strength of weldment. This is another reason of the current achievement.

Sustained increase in plastic use has placed a significant burden on waste disposal infrastructure. Pyrolysis is the process of decomposing high-molecular-weight compounds by heating waste plastics at 500–1000 °C without oxygen. This process considerably reduces greenhouse gas emissions and has a high alternative energy effect (0.57 TOE ton[sup.−1] ). After a separation process, the oil produced by pyrolysis (C5–C20) can yield naphtha oil (C6–C7). Subsequently, hydrogen can be produced through a reforming reaction of this naphtha oil. Here, we produced hydrogen from waste plastic pyrolysis oil over a Ni/Ce-Zr-Mg/Al[sub.2] O[sub.3] catalyst using a steam reforming process. A model oil combining the major substances of C6 and C7 (hexane, hexene, heptane, heptene, and toluene) was formed. From the reaction products, the hydrogen yield was obtained based on analysis of H[sub.2] , CO, and CO[sub.2] concentrations using gas chromatography. The effect of N[sub.2] and O[sub.2] addition on hydrogen yield was analyzed within a temperature range of 750–850 °C, steam/carbon (S/C) ratio of 0.6–4, and space velocity of 7600–19,100 h[sup.−1] . In addition, a durability test was performed using 3 wt.% Ni/Ce-Zr-Mg/Al[sub.2] O[sub.3] catalysts for 100 h; a hydrogen yield of 91.3% was maintained from the refined waste plastic oil.

In GMAW (gas metal arc welding) of Zn (zinc)-coated steel sheets, defects such as pores occur in the weld due to trapped Zn vapor. To solve this problem, we investigated the pore-free welding condition using conventional solid wire. We verified through experiments that the combination of 20% CO2-Ar shielding gas and DCEP (direct current electrode positive) polarity has a higher pore-free performance than other combinations. A higher performance of pore-free welding was obtained by reducing the CTWD (contact tip to work distance) and using ER70S-3 wire. In conclusion, the optimized welding conditions at 10 mm overlap, 80 cm/min welding speed, and 30° work angle are 160 A arc current, 20 V voltage, 15 mm CTWD, 10° push angle, DCEP polarity, 20% CO2-Ar shielding gas with 20 L/min flow rate, and ER70S-3 wire type. For flow pattern analysis, a high-speed camera with blue laser was used, and it was observed that a longer weld pool and smaller droplets could improve the efficiency of Zn vapor emission. With ER70S-3, a longer weld pool can be obtained, as it has a lower viscosity due to lower percentages of Si and Mn in its composition.

In this paper, we define the sum of RKBSs using the characterization theorem of RKBSs and show that the sum of RKBSs is compatible with the direct sum of feature spaces. Moreover, we decompose the integral RKBS into the sum of \\(p\\)-norm RKBSs. Finally, we provide applications for the structural understanding of the integral RKBS class.

In this paper, we define the sum of RKBSs using the characterization theorem of RKBSs and show that the sum of RKBSs is compatible with the direct sum of feature spaces. Moreover, we decompose the integral RKBS into the sum of \\(p\\)-norm RKBSs. Finally, we provide applications for the structural understanding of the integral RKBS class.

In this paper, we present Coyote C++, a fully automated white-box unit testing tool for C and C++. Whereas existing tools have struggled to realize unit test generation for C++, Coyote C++ is able to produce high coverage results from unit test generation at a testing speed of over 10,000 statements per hour. This impressive feat is made possible by the combination of a powerful concolic execution engine with sophisticated automated test harness generation. Additionally, the GUI of Coyote C++ displays detailed code coverage visualizations and provides various configuration features for users seeking to manually optimize their coverage results. Combining potent one-click automated testing with rich support for manual tweaking, Coyote C++ is the first automated testing tool that is practical enough to make automated testing of C++ code truly viable in industrial applications.