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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Effects of mill rotational speed on the batch grinding kinetics of a UG2 platinum ore

Makgoale, Dineo Mokganyetji 11 1900 (has links)
In this study, the effect of speed was investigated on the breakage rate of UG2 platinum ore in a batch mill of 5 dm3 and 175 mm internal diameter. One size fraction method was carried out to perform the experiment. Five mono-sized fractions in the range of 1.180 mm to 0.212 mm separated by √2 series interval were prepared. The fractions were milled at different grinding times (0.5, 2, 4, 15 and 30 min) and three fractions of mill critical speed were considered (20%, 30%, and 40%). The target of critical speed below 50% was due to the need of lower energy consumption in milling processes. The selection and breakage function parameters were determined and compared for fractions of critical speed. First the grinding kinetics of the ore was determined and it was found that the material breaks in non-first order manner. Thereafter, effective mean rate of breakage was determined. It was found that the rate of breakage increased with increase of mill speed and optimum speed was not reached in the range of chosen mill speed fractions. Again the rate of breakage was plotted as a function of particle size, the optimum size was 0.8 mm when milling at 30% critical speed. As for 20% and 30% optimum size was not reached. The selection function parameters estimated at 30% critical speed were 𝑎0 = 0.04 min−1 , 𝛼 = 1.36, 𝜇 = 0.9 mm, and Λ = 3. Breakage function parameters were determined and was noticed that the material UG2 platinum ore is non-normalised, i.e. Φ value was changing from 0.25 to 0.90 depending on feed size and mill speed. The parameters 𝛽 and 𝛾 were constant at 7.3 and 1.17 respectively. / College of Science, Engineering and Technology / M. Tech. (Chemical Engineering)
42

Development of Advanced Process Control for Controlling a Digital Twin as a Part of Virtual Commissioning

Uddin, Md Mehrab January 2021 (has links)
Over the last few decades, the complexity and variety of automation systems have increased dramatically. Commissioning has grown more and more critical for the entire industry. Conventional commissioning is time-consuming and expensive. It's always been a challenge in manufacturing to put new designs into production or implement new technologies, control codes, or tactics. In Virtual Commissioning (VC), control programs of the physical system's Digital Twin (DT) can be validated in Software-in-the-Loop (SIL) before the actual commissioning. The emergence of new VC tools and methods has become a tremendous advantage, bringing the values of shorter duration, flexibility, and lower risks to the commissioning process. In this thesis, advanced process control was developed using the software Matlab and Simulink in conjunction with the engineering tools S7-PLCSIM Advanced and STEP 7 TIA Portal to conduct VC. A VC approach with four key steps is taken to evaluate the possibility of validating advanced process control. The steps are modeling DT of a rolling mill, model-based control design, simulation model development in Simulink, communication between the simulation model and the PLC program using S-7 TIA Portal, and PLCSIM Advanced. Also, a simulated Human-Machine Interface was designed to operate and visualize the process. VC of the rolling mill process was verified and validated by Model-in-the-Loop (MIL) and SIL simulation. The simulation gives satisfactory results as both MIL and SIL show identical outputs of the process.

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