Casting of recycled aluminum, Al + Cu + Mg alloy formation and lamination process of an electric current conductor

This research presents a methodology for the recycling process via casting, in which aluminum cans and primary (commercial) aluminum are transformed into a laminated tape, with the possibility of industrial application. This research was classified as bibliographic, exploratory, and experimental, since it used qualitative techniques to evaluate alternative materials. Its objective was to incorporate materials of different properties that could favor the making of a tape to be laminated. In the first casting, a recycled aluminum ingot was formed only with aluminum from beverage cans and had a material yield of 51%. In a second casting, commercial aluminum was added to the recycled aluminum ingot. After the casting process with the two cast materials, the ingot had a yield of 90%. A third casting was conducted together with the aluminum that was already formed by the ingot (50% recycled and 50% commercial). The purpose of this ingot was to incorporate other materials that could provide some characteristics, such as malleability and conductivity. The third casting was made from the second ingot, and incorporated copper and magnesium. For the design of the laminated tape, a cast was made to receive the molten aluminum from the third casting. The aluminum was cast into this mold and three tapes were produced, one with a thickness of 2 mm, another with a thickness of 3 mm and the last with a thickness of 4 mm. With these tapes, the objective was to laminate them in order to reduce their thickness to values ​​close to 0.5 mm. The casting process of aluminum cans with the addition of commercial aluminum, plus the incorporation of copper and magnesium, demonstrated facilities for thickness reduction in the process of making laminated tapes.

Study on Transformer JED Cap Actuation Systems in the Field of Very Strong Electromagnetic Disturbances

This work presents the results of research on the influence of strong external electromagnetic fields on the operation of JED spark caps activated by transformer systems. The tests were carried out in order to determine the conditions of safe use of JED caps installed in control systems of generators producing electric current pulses using the principle of an explosive magnetic field cumulation [1]. For this purpose, the measurements of the voltages induced in the transformer JED spark cap actuation system were performed using sinusoidal external current with an amplitude of 10 kA for a period of 15 microseconds. This current flowed at a distance from d = 10 mm to d = 40 mm from the axis of the ferrite cores of the applied transformers: a closed core with an outer diameter of 20 mm, an inner diameter of 10 mm and a height of 10 mm and an open core with a diameter of 6 mm and a length of 25 mm. The transformers used in Air Force Institute of Technology (AFIT) were placed alternately parallel and perpendicular to the axis of the current conductor. In the case of a transformer with a cylindrical open core perpendicular to the current axis, the induced voltages significantly exceeded the values at which the caps were activated (about 2 kV) and became lower than these values at d of about 40 mm. Toroidal closed cores provided induced voltages of up to 200 V (10 times lower) for all configurations tested. The measurements were performed using a system and methods developed at AFIT.

The Influence of Temperature and Deformation Ratio on Structure Formation and Physico-Mechanical Properties of Powder Materials

The paper presents the materials on researching the use of current conductor copper waste for getting new functional materials. The changes of maximum deformation ratio, density, microstructure and hardness of powder copper preforms at different temperatures and deformation rates have been studied. The result is that the value of the maximum deformation ratio depends on kinetics of dynamic weakening processes. The change of the microstructure depending on the temperature and deformation ratio has been scrutinized. It has been established that the most fine-grained structure was got at the temperatures of dynamical recovery and recrystallization. The temperature intervals of stamping for manufacturing products by pressing are recommended. On the basis of experimental researches a resource-saving manufacturing method of producing axisymmetric details of high density from powder copper material with the use of maximum deformation ratios has been elaborated.

Students’ knowledge test control in Physics

Controlling learners’ educational achievements in our time performs the most important function of learning. Scientists and methodologists argue that the test control of students’ academic achievement meets the requirements of quantitative and objective measurement of learners’ knowledge, skills and abilities. The relevance of the test controlling method of learners’ academic achievements is dictated also by the introduction of the independent external evaluation (IEE) as a final certification of school leavers. With the emergence of computer classes, the use of tests became available and appropriate. The use of computers in the testing process greatly enhances the benefits of this type of control. This paper is aimed at studying experimentally the impact of the controlling testing on enhancing learners’ educational achievements in Physics and managing learners’ cognitive activity. We have been prepared the system of test questions on the following topics: “We begin to study Physics”, “Mechanical work. Units of work”, “Power and its units”, “Electric current. Conductor Resistance”, “Serial and Parallel Conductor Connection”, “Ideal Gas Laws”, “Atomic Physics. Spectrums”. The tests were developed in order to identify the students’ acquisitions of the main issues constituting the educational material / programme, as opposed to revealing some amount of information from the learner's side. In our opinion, it is important for students to master the level of education that would become the basis for further self-improvement of their own education, their own opportunities to overcome the challenges that the life postures to him / her in today's society. Therefore, the main task while developing the test tasks was the formation of certain subject and life-oriented competences. We conducted a pedagogical experiment to introduce the test control of learners' knowledge in Physics. A series of lessons were conducted using the test survey in the experimental class, but no tests were used in the control class. Using the example of testing 8th grade schoolchildren in Physics it was detected that the use of a systematic test control of knowledge acquisition at corresponding lessons Physics allowed the students to demonstrate better knowledge of certain topics at sufficient and high levels. Keywords: testing control, learners’ self-educational competence in Physics, creative thinking.

Experimental Studies of an Eddy Current Transducer with Spatially Periodic Fields

The purpose of this study is to perform a comparative analysis of the experimentally obtained and calculated values of the measuring windings total EMF amplitudes of the eddy current transducer with spatially periodic fields when magnetic and nonmagnetic cylindrical product are placed in it. To realize this goal in the work, a transducer with translational symmetry of excitation magnetic field has been developed. Translation symmetry typical example is the field of a long current conductor. The paper considers quasi-static electromagnetic field with the wavelength that exceeds characteristic transverse dimensions of conductor and cylinder. As the study result it is seen a satisfactory coincidence of the calculated and experimentally obtained values of the EMF of the transducer output signal in the cases of the product absence and with variety of products. As for example for measuring windings with angular coordinates φ = 30° and 60° an error of voltage values difference is less than 10%. The study shows that the advantage of such transducers while operating on one fixed frequency is capability to perform the multi-parameter testing on account of processing of certain amount of some spatial harmonics of excitation field.

Off-Center Error Correction of AMR Yokeless Current Transducer

We present a method of calibration and error correction of the AMR yokeless current transducer consisting of a circular array of eight anisotropic magnetoresistors (AMR) with one feedback compensation loop. The main sources of errors are the nonidentical parameters of AMR sensors and off-center position of the measured current. It is well known that AMR sensors from the same batch have 2% spread of the sensitivity; we found that the variation of the factor of the internal compensation coil is the same. We developed a novel calibration process using the readings of individual residual uncompensated voltages of the AMRs. The position of the current inside the measurement hole is estimated from the individual voltages considering the influence of external DC magnetic field such as the Earth’s field. During the calibration phase, the sensor outputs are measured for several positions of the current conductor inside the measuring hole. As a result of calibration the lookup table of error corrections is calculated and stored in the memory, and then these values are used for the correction during the measurement of the unknown current. This procedure reduces the off-center error from 0.4% to 0.06%.