Prediction of Surface Profile Evolution of Workpiece and Lapping plate in Lapping Process

Lapping has a history of hundreds of years, yet it still relies on the experience of workers. To improve the automaticity and controllability of the lapping process, a modeling method of friction and wear is developed to predict the surface profile evolution of the workpiece and lapping plate in the lapping process. In the proposed method, by solving the balance equations of resultant force and moment, the inclination angles of the workpiece can be calculated, thus more accurate contact pressure distribution of the workpiece/lapping plate interface can be calculated. Combined with the material removal rate model, the continuous evolution process of the workpiece and lapping plate can be predicted in the lapping process. The modeling method was validated by a lapping test of a flat optical glass (Φ 100 mm) with a composite copper plate. The results show that the proposed method can predict the evolution of the surface profile of the workpiece and lapping plate with high accuracy. Consequently, the lapping plate can be dressed at the right time point. Benefit from this, in the validation test the PV value of the workpiece (with 5 mm edge exclusion) was reduced from 5.279 μm to 0.267 μm in 30 min. The proposed surface profile evolution modeling method not only improves the lapping efficiency but also provides an opportunity to understand the lapping process.

Optimization of the Hemispherical Solar Distiller Performance Augmented by Different Basin Materials (steel, zinc, and copper) and Reflective Mirrors

The present comprehensive study aims to solve the problem of declining drinking water productivity from solar distillers. The hemispherical distillers are characterized by having the large condensing and receiving surface area, so the utilization of basin materials with high thermal conductivity and reflective mirrors are very effective to enhance a cumulative production of hemispherical distillation. To get the optimal basin materials with the reflective mirror that achieves the highest hemispherical distiller’s performance, three high thermal conductivity basin materials (steel, zinc, and copper) with reflective mirror were tested at the same conditions and compared to reference hemispherical unit. To realize this idea, four distillers was fabricated and tested at a same climate condition namely: Hemispherical solar Distiller with Black Silicone Walls (HSD-BSW), Hemispherical Solar Distiller with Steel Plate and Reflective Mirror (HSD-SPRM), Hemispherical Solar Distiller with Zinc Plate and Reflective Mirror (HSD-ZPRM), and Hemispherical Solar Distiller with Copper Plate and Reflective Mirror (HSD-CPRM). The experimental results presented that the utilization of copper basin materials and reflective mirror (HSD-CPRM) represents the good option to achieve the highest performance of hemispherical distiller, use the copper basin materials and reflective mirror (HSD-CPRM) gives a cumulative production reached 9500 mL/m2 day with improvement of 104.3% compared to reference hemispherical distiller (HSD-BSW). Also, use the copper basin materials and reflective mirror (HSD-CPRM) improves the daily thermal efficiency and exergy efficiency by 102.4% and 194.9%, respectively compared to HSD-BSW. The comprehensive economic analysis concluded that the use of copper basin materials and reflective mirrors (HSD-CPRM) reduced the distillate water cost per liter by 44.1% compared to HSD-BSW.

A Simulation Method for the Optimization of Cooling Water Slot Structure in Slab Continuous Casting Mold Combined With SEN

The temperature field in the full 3D finite element mold model combined with submerged entry nozzle(SEN)(Full SEN-3D FEMM) is simulated with Fluent of ANSYS 18.0 Package to apply the maximum heat flux density on the heat face of mold copper plate obtained through this simulation to the element model of the copper plate, and thermal stress and strain simulations on the copper plate and stainless back ones are conducted with Workbench of ANSYS 18.0 Package to confirm the reasonable designing factors for the water slot structure on the copper plate. The maximum heat flux densities on the wide and narrow heat faces of the copper plates are given on the initial shock areas of molten steel flux injected through SEN. With constant heat flux density on the heat face, the more the thickness of copper plate increases, the more the max- and min temperatures increase and the difference between them decreases. Elastic and plastic deformations on the copper plate are made during continuous casting(CC) process; the former occurs around the water slots and the latter around the heat face with the highest temperature, which regards 20-18-17 as the most reasonable one among 4 plans for the water slot structure.

Conductive materials for connecting tires of multi-element accumulator traction batteries

The article deals with the choice of materials for connecting tires of traction batteries (TB). The optimal parameters of their spot welding with batteries are experimentally established (the first pulse with a current of 7 kA duration of 1 ms, the break between the pulses of 1 ms, the second pulse with a current of 7 kA duration of 2 ms). When operating the traction battery on electric vehicles, the resistance of the connecting tires should not lead to heating of the batteries in order to avoid overheating above 60 °C. In most modern TB, consisting of Li-ion elements, a nickel tape is used for the connection. To ensure the weldability of materials (copper–nickel or nickel–nickel), it is important that the operating temperature is reached at a short-term current pulse in the welding zone. One of the solutions to this problem is the application of a metal coating. Experiments were conducted on the weldability of various materials, including those with applied coatings. The best results in weldability were shown by tires made of tinned copper, which was welded to nickel plates (emitting the battery body). Tear tests of the welded samples were carried out. The tensile strength of the original copper tires was 340–450 MPa. When welding copper–nickel and copper(tinned) – nickel plates, the strength limit values reach 70 % of the strength of the original copper plate. On the basis of the obtained experimental data, a pilot batch of battery TB was manufactured, which successfully passed tests for compliance with the technical requirements for the strength and the value of the transition resistances of the welded joints of connecting buses with batteries.

Printability of Collecting Electrode Using AJP for New Construction of Photovoltaic Device

In 2018, the European Parliament and Council laid down a directive about the promotion of the use of energy from renewable sources connected with the Paris Agreement, which sets a global ambition on climate change mitigation through deep and fast cuts in greenhouse gas emissions. Since then, the science world has been even more focused on the development of green technologies such as wind farms, waterpower stations, and photovoltaics as the European Union is preparing to shift to renewables-based energy systems. Each green power technology has its own problems and limitations. Nevertheless, for environmental protection, new power technologies have to be implemented in the near future as primary power sources. Described in this article is the application of aerosol jet printing in manufacture of photovoltaic cells, moving the technology boundaries further toward highly efficient, cost-effective, green power production. The research focused on utilizing aerosol jet printing technology to create finger-shaped collecting electrodes on a newly constructed, non-silicon photovoltaic cell, based on metal oxides. Three commercial nanosilver inks were investigated considering their printing parameters, printability on the specified substrate (AZO-coated glass, AZO-coated copper plate), resistivity of the cured composite, quality of the overprints, and application in photovoltaics. As a result, we obtained finger-shaped collecting electrodes with a resistivity of 3.5 µΩ∙cm and 8 µm width, which compares well with the literature.

The use of artwork to document geologic systems in The Geology of Russia (1845)

ABSTRACT Artwork in The Geology of Russia (1845) documents the extent and fossil content of several Paleozoic systems in Europe and large tracts of Russia. That artwork conveys a sense of landscape, portrays the distribution of strata both at and below the surface, and documents the fossil evidence for identifying several Paleozoic geologic systems. The artwork includes wood engravings, lithographs, zincographs, and copper plate engravings. The choice of technique was governed by the content and desired character of the images and the logistics of printing. Roderick Murchison was a master of organization who commissioned, assembled, and oversaw the production of artwork that was crucial to presenting the evidence for the Paleozoic systems documented in The Geology of Russia (1845).

COMPUTER SIMULATION OF CRACK GROWTH. MOLECULAR DYNAMICS METHOD

The aim of the study is to determine the stress intensity factors using molecular dynamics (MD) method. In the course of the study, a computer simulation of the propagation of a central crack in a copper plate was carried out. The simulation was performed in the LAMMPS (Large-scale Atomic / Molecular Massively Parallel Simulator) software package. A comprehensive study of the influence of geometric characteristics (model dimensions, crack length), temperature, strain rate and loading mixing parameter on the plate strength, crack growth and direction was carried out. The article proposes a method for determining the coefficients of the asymptotic expansion of M. Williams stress fields. The analysis of the influence of the choice of points on the calculation of the coefficients and the comparison of the results obtained with the analytical solution are carried out.

Effect of Residual Aluminum Thickness on Microstructure and Strength of Friction Stir Spot Welded Aluminum Alloy/Copper Lap Joint

Dissimilar metal lap joining of A5052 aluminum alloy plate and C1100 pure copper plate was performed by using friction stir spot welding. The rotating welding tool, which was composed of a probe part and a shoulder part, was plunged from the aluminum alloy plate which was overlapped on the copper plate, and residual aluminum alloy thickness under the probe part of the welding tool after plunging of the welding tool was controlled in the range from 0 mm to 0.4 mm. The strength of the welding interface was evaluated by using tensile-shear test. Microstructure of the welding interface was examined by using an optical microscope and a field emission scanning electron microscope. The welding was achieved at the residual aluminum alloy thickness under the probe part of the welding tool below 0.3 mm. The welded area was formed at aluminum alloy/copper interface located under the probe part of the welding tool, and its width increased with decreasing the residual aluminum alloy thickness. A characteristic laminate structure was produced in the copper matrix near the welding interface. In the joint fabricated at the residual aluminum alloy thickness below 0.1 mm, hook of Cu was formed at edge of the welded area. The fracture did not occur at the welding interface. A remarkable improvement in strength was observed in the joint fabricated at the residual aluminum alloy thickness below 0.1 mm. The formation of laminate structure and hook is considered to result in joint strength improvement.