Research on Tension Control System of Reciprocating Winding

When the enameled wire is winded onto the poles of the motor stator or rotor, the winding quality hugely relies on the control precision of the tension. Therefore, it is necessary to control the tension of the enameled wire in winding process. A tension control system is built with single chip microcomputer, the encoder and the servo motor. The PID feedback controller and feedforward controller are combined to form feedforward feedback controller, which using feedback information of swing angle deviation and feedforward information of wire frame position to adjust the pay off speed dynamically and control tension of enameled wire further. A procedural experimental modelling method is discussed in order to identify the feedforward model. The experiment is performed, it is found that in the typical situation of setting tension 1500 g, the tension fluctuation rate of the PID controller with feedforward model is only 2%, which is far better than that of pure PID controller with a fluctuation rate of 14%. The result shows that the proposed experimental modelling method hosts the characteristics of good accuracy, universality and applicability.

PEFC System Reactant Gas Supply Management and Anode Purging Strategy: An Experimental Approach

In this report, a 5 kW PEFC system running on dry hydrogen with an appropriately sized Balance of Plant (BoP) was used to conduct experimental studies and analyses of gas supply subsystems. The improper rating and use of BoP components has been found to increase parasitic loads, which consequently has a direct effect on the polymer electrolyte fuel cell (PEFC) system efficiency. Therefore, the minimisation of parasitic loads while maintaining desired performance is crucial. Nevertheless, little has been found in the literature regarding experimental work on large stacks and BoP, with the majority of papers concentrating on modelling. A particular interest of our study was the anode side of the fuel cell. Additionally the rationale behind the use of hydrogen anode recirculation was scrutinised, and a novel anode purging strategy was developed and implemented. Through experimental modelling, the use of cathode air blower was minimised since it was found to be the biggest contributor to the parasitic loads.

METHOD OF THEORY OF DIMENSIONS IN EXPERIMENTAL RESEARCH OF SYSTEMS AND PROCESSES

The method and parameters of experimental modelling of systems and processes in mechanical engineering are substantiated. The theory of similarity and dimensionality is used as an intermediate link between theory and experiment. The dimension of the factor space depends on the number of factors. The set of factors is grouped into dimensionless similarity criteria. The selected criteria are in certain dependence, such as the Galileo test, Euler and Reynolds numbers. Examples of application in experimental studies are given. The use of dimension theory in a factor-planned experiment allows reducing the number of factors, simplifies the mathematical interpretation of the response criterion and provides a graphical representation in the form of 3-D model.

Reduced Scale Experimental Modelling of Distributed Thermal Response Tests for the Estimation of the Ground Thermal Conductivity

The knowledge of the ground thermal properties, and in particular the ground thermal conductivity is fundamental for the correct sizing of the Ground Coupled Heat Pump (GCHP) plant. The Thermal Response Test (TRT) is the most used experimental technique for estimating the ground thermal conductivity. This paper presents an experimental setup aimed to realise a suitable scale prototype of the real borehole heat exchanger (BHE) and the surrounding ground for reduced scale TRT experiments. The scaled ground volume is realised with a slate block. Numerical analyses were carried out to correctly determine suitable geometric and operational parameters for the present setup. The scaled heat exchanger, inserted into the block, is created with additive technology (3D printer) and equipped with a central electrical heater along its entire depth and with temperature sensors at different radial distances and depths. Present measurements highlight the possibility to reliably perform a TRT experiment and to estimate the slate/ground thermal conductivity with an agreement of about +12% with respect to measurements provided by a standard commercial conductivity meter on proper cylindrical samples of the same material and onto 10 different portions of the slate block.

Mining under the early metal in the context of Kartamysh ore occurrence of Ukrainian Donbas

Purpose is to identify process engineering of mining under the Late Bronze age (18th-13th centuries BCE) in the context of copper deposits in the Eastern Ukraine. Among other things, it concerns analysis of manufacturing artifacts (i.e. ore production and preparation) in Kartamysh archeological area within the copper-ore territory of Bakhmut basin of Donbas. Methods. Following methods have been applied: a comparative historical method supported by typological archaeological approach; statistical procedures; engineering and geological methods to determine extraction volumes and evaluate copper ore extraction from the mines in Kartamysh archaeological area as well as structural and technologic analysis; functional and typological analysis; traceological analysis; experimental modelling; and carbon dating. Findings. Analysis of the specialized mining artifacts in Kartamysh archaeological area as well as mining artifacts within other copper-ore deposits in Bakhmut basin, extracted actively under the Late Bronze age, has made it possible to consider newly a number of important issues connected with process engineering of mining, specialization and labour division of ancient miners as well as evaluate significance of Donbas copper mines for the system of metal production development in the Eastern Europe of the second millennium BCE. Originality.Analysis of Kartamysh archaeological area, where the majority of business performance objects are connected with mining, has helped the authors consider specialization of the industrial systems (i.e. different-purpose mine workings, various mining tools, and areas to prepare ore) right from the viewpoint of the production method. Since similar situation is typical for other Donets complex artifacts, being involved in scientific terminology as the mining and smelting one, it would be more reasonable to represent it as Donets ore mining system owing to its specialization in the integrated copper ore extraction and preparation. Practical implications.The research results develop the history of mining science and engineering inclusive of ancient mining history in the Eastern Ukraine. They may be applied to train mining experts and in the process of creation of museum exhibitions (looking ahead, creation of Kartamysh skansen) while synthesizing technical and humanitarian aspects of engineering activities.