Self-Inductance Calculation of the Archimedean Spiral Coil

In this paper, a new method to calculate the self-inductance of the Archimedean spiral coil is presented. The proposed method is derived by solving Neumann’s integral formula, and the numerical tool is used to calculate the inductance value. The calculation results are verified with several conventional formulas derived from the Wheeler formula or its modified form and 3D finite element analyses. The comparison with simulation results shows that the conventional formula has an error of above 40% compared to the proposed method, which has below 7% when the wire diameter is reduced. To further check the validity, different sizes of the spiral coil are fabricated by changing the geometrical parameters such as the number of turns, turn spacing, inner radius, outer radius, and wire diameter. Litz wire is chosen for making the spiral coil, and bobbins are made using a 3D printer. Finally, the calculation results are compared with the experimental result. The error between them is less than 2%. The comparison with the conventional formulas, simulation, and measurement results shows the accuracy of the proposed method. This method can be used to calculate the self-inductance of wireless power coils, inductors and antenna design.

Design and Experiment of the Buckwheat Hill-Drop Planter Hole Forming Device

The hole forming device is an important element of the buckwheat hill-drop planter, and its design level directly affects the seeding quality of the hill-drop planter. A hole forming device with a duckbill structure is widely used in hill-drop planters for wheat, cotton, peanuts, etc. According to the requirements of buckwheat seeding operations, this study designs the components of the duckbill hole forming device. It is determined that the duckbill upper jaw length is 65 mm, the duckbills number is 10, the pressure plate on the spring side length is 90 mm, the duckbill opening size is 8.79 mm, and the duckbill effective opening time is 0.1 s. Through co-simulation analysis of discrete element software EDEM (DEM-Solutions, Edinburgh, United Kingdom) and multi-body dynamics software RecurDyn (FunctionBay, Inc., Seongnam-si, South Korea), it is measured that when the pressure plate on the spring side is directly below the rotation axis of the dibber wheel, the spring compression is 33.3 mm, the pressure on the pressure plate is 95–102.6 N, and the contact time of a single duckbill with the soil is 0.2 s at a speed of 40 r/min. Based on the results of the design and simulation analysis, the large end diameter, small end diameter, original length and wire diameter of the duckbill spring are 36 mm, 26 mm, 60 mm, and 1.8 mm, respectively. An experimental bench for the seeding wheel of a buckwheat hill-drop planter was built, and three wire diameter duckbill springs of 1.6 mm, 1.8 mm and 2.0 mm were tested to verify the simulation and calculation results. The experimental results show that the optimal wire diameter of the duckbill spring is 1.8 mm. Finally, a single factor experiment of the dibber wheel rotation speed was carried out. The experimental results show that when the rotation speed of the dibber wheel is 40–65 r/min, the seeding qualification rate, seeding void hole rate and seeding damage rate of the buckwheat hill-drop planter are ≥85.3%, 0, and <0.3%, respectively. This study provides a basis and reference for the hole forming device design of a buckwheat hill-drop planter.

One hundred kilojoules of energy storage in water wire electric explosion deposition energy study

In this experiment, the electro-explosive deposition energy in water of aluminum-magnesium welding wire model ER5356 at 100 kJ capacitive storage energy was investigated. The loop current and the load discharge voltage during the wire electrical explosion were measured using a self-integrating Roche coil and a capacitive voltage divider, respectively. The physical process of electrical explosion and the energy deposition process were delineated by the measured loop currents and load voltages. The current waveform and load voltage of the electric explosion in water of 1.2 mm-3.0 mm diameter Al-Mg wire at 100 kJ stored energy were measured; the changes of load resistance value, load power and deposition energy of the wire loaded with electric explosion were calculated. The results show that the peak circuit current and peak time point decrease and then increase with increasing diameter, and the minimum value is achieved at 1.6 mm wire diameter; the load voltage and load resistance values gradually decrease with increasing diameter; the load power and total deposited energy of discharge achieve the maximum value at 2.0 mm diameter. At 100 kJ energy storage, there is an optimal range between 1.6 mm and 2.4 mm wire diameter.

Information storage in permalloy modulated magnetic nanowires

A long piece of magnetic material shaped as a central cylindrical wire (diameter $$d=50$$ d = 50 nm) with two wider coaxial cylindrical portions (diameter $$D=90$$ D = 90 nm and thickness $$t=100$$ t = 100 nm) defines a bimodulated nanowire. Micromagnetism is invoked to study the equilibrium energy of the system under the variations of the positions of the modulations along the wire. The system can be thought of as composed of five independent elements (3 segments and 2 modulations) leading to $$2^5=32$$ 2 5 = 32 possible different magnetic configurations, which will be later simplified to 4. We investigate the stability of the configurations depending on the positions of the modulations. The relative chirality of the modulations has negligible contributions to the energy and they have no effect on the stability of the stored configuration. However, the modulations are extremely important in pinning the domain walls that lead to consider each segment as independent from the rest. A phase diagram reporting the stability of the inscribed magnetic configurations is produced. The stability of the system was then tested under the action of external magnetic fields and it was found that more than 50 mT are necessary to alter the inscribed information. The main purpose of this paper is to find whether a prototype like this can be complemented to be used as a magnetic key or to store information in the form of firmware. Present results indicate that both possibilities are feasible.

Optimum Design of Square Air-Core Electromagnetic Coil System

Designs of electromagnetic (EM) coil have attracted a lot of attention in the research community due to its applications in several areas of human endeavours. However, the optimal selection of coil wire size and current in the design of Square Air-Core Multi-turn Multilayer Electromagnetic Coil (SAMMEC) with significant wire diameter for both safe and cost-effective products has not been given enough research attention. Therefore, the equation for the flux density produced by a rectangular loop of wire was adopted in the modelling of SAMMEC with significant wire diameter. A coil design chart was constructed based on the developed model and design specifications. Both the feasible and non-feasible design regions and the line of optimum magnetic flux density were identified on the constructed chart. The appropriate wire size and current for the coil were both determined from the design-chart. The diameter, length, resistance, copper loss, and weight of the selected wire for the generation of 0.06 T flux density were found to be 0.00326 m, 267.01 m, 0.5502 Ω, 263.87 W, and 19.86 kg respectively. The selected wire can produce an optimum flux density of 0.066 T with current of 24 Amp and associated copper loss of 316.92 W. Keywords—Air core, Electromagnetic coil, Magnetic flux density, Multilayer, Multi-turn

Optimization of microstructural and mechanical properties of brass wire produced by friction stir extrusion using Taguchi method

Friction stir back extrusion is used to produce brass wires from its chips, and then the process parameters are optimized using Taguchi L9 orthogonal design of experiments. The rotational speed, traverse speed, and the produced wire diameter are the parameters taken into consideration. The optimum process parameters are determined with respect to grain size, microhardness, and ultimate pressure strength of the produced samples. The predicted optimum values for output parameters are confirmed by conducting the confirmation test using optimum parameters. Analysis of variance shows that the rotational speed is the most dominant factor in determining the grain size and microhardness of the produced wires, and the tool traverse speed and the wire diameter are the second and the third effective parameters. However, in terms of the produced wires ultimate pressure strength, the traverse speed is the most dominant factor rather than the rotational speed. The optimum values for the rotational speed, the traverse speed, and the wire diameter are 500 r/min, 31.5 mm/min, and 6 mm, respectively, and the produced wire, by these optimum parameters, presents 14.17 µm, 127.1 HV, and 904.7 MPa for the grain size, the microhardness, and the ultimate pressure strength, respectively.

Information storage in permalloy modulated magnetic nanowires

A long piece of magnetic material shaped as a central cylindrical wire (diameter d = 50 nm) with two wider coaxial cylindrical portions (diameter D = 90 nm and thickness t = 100 nm) defines a bimodulated nanowire. Micromagnetism is invoked to study the equilibrium energy of the system under the variations of the positions of the modulations along the wire. The system can be thought of as composed of 5 independent elements (3 segments and 2 modulations) leading to 25 = 32 different magnetic configurations. We investigate the stability of the configurations depending on the positions of the modulations. The relative chirality of the modulations has negligible contributions to the energy and they have no effect in the stability of the stored configuration. However, the modulations are extremely important in pinning the domain walls that lead to consider each segment as independent from the rest. A phase diagram reporting the stability of the inscribed magnetic configurations is produced. The stability of the system was then tested under the action of external magnetic fields and it is found that more than 50 mT are necessary to alter the inscribed information. The main purpose of this paper is to find weather a prototype like this can complemented to be used as firmware or magnetic keys. Present results indicate that this is feasible.