Applications of Dynamic Modeling in Crushing Plants

Modeling is a tool to describe phenomena in a simplified way, and the models can then be used to simulate these phenomena. Models of equipment used in the mining and aggregate industries can be used for process simulations of the processes in those industries to improve the operations. To study processes and the operation of processes, time dynamic models are a great tool. This thesis focuses on applications of time dynamic modeling in crushing plants. The time dynamic models predict the output of the equipment as a function of time. The work presented within this thesis focuses on three areas; Unit modeling, process modeling, and control modeling.Unit modeling refers to developing models of single processing units, which could be a comminution unit, classification unit, or materials handling unit. The new models presented in this thesis are for jaw crushers, high pressure grinding rolls (HPGR), and storage units (e.g., bin, silo, or stockpile). The developed models are based on the fundamental insight of the physics that happens within the unit. The validity of the models is aimed to be broad and cover many operating points and uses. The models are intended for high fidelity process simulation applications.Process modeling refers to the modeling of many interconnected units, and the modeling presented in this thesis has been done with both high-fidelity unit models and with simplified models. Both high fidelity and simple simulations are demonstrated within the thesis. The simpler models are used to try new concepts of plant design or control and study plant robustness or ability to handle variations. Meanwhile, the high-fidelity models can be used to study topics such as particle size distribution, debottlenecking and specific control issues.Control modeling refers to developing controller models to control plants like those modeled within the process modeling section. Optimal control, such as model predictive control (MPC), relies on models to steer processes optimally relative to some objective. The models within those controllers have been discussed in this thesis. Additionally, being able to move between the various fidelity domains of models is beneficial for this application. In this thesis, multiple new models and methods are presented, along with how they can be applied within the minerals processing and aggregate industry, ultimately improving the efficiency and performance of the industries

Efficient modeling and control of crushing processes in minerals processing

Modeling and simulation is a tool to explore and increase the understanding of a phenomenon. This thesis focuses on developing models of crushers and equipment used in the mining industry. Specifically, the focus is on a branch of modeling called time dynamic modeling which is a model that gives an output as a function of time. The work is divided into three areas: physical modeling, control modeling, and circuit modeling. Physical modeling deals with how to develop high fidelity unit models of equipment, in this thesis, a model of a jaw crusher and of an HPGR are presented. These models are aimed to be predictive and should predict the process variables under a specific set of operating conditions. The models are developed with the process parameters that are used in the physical unit, in the case of the HPGR, roller speed, and hydraulic pressure. The parameters within the models are parameters with units and have real physical meaning; for example, a dimension of the machine. The topic of control modeling focuses on how to apply the knowledge from modeling in the control domain to improve operations. An example of setting up a model predictive controller and using it to control a crushing circuit simulation is demonstrated. Model predictive control is an optimal control strategy that can be used to drive the circuit towards a specific goal. As the demand is increased on the mining companies to perform better these types of controllers and operation improving actions are important. This thesis aims to target some of the challenges involved in improving plant operation and control. Within circuit modeling, a broader perspective is taken to study the operations of an entire circuit or plant. The study presented in this thesis focuses on how sensitive a plant is to variations and how the plant design itself will affect the plant\u27s ability to cope with variations. The approach has been to simulate faster and to use less complex models many times to determine limits and ranges. The method shows potential to understand a circuit better before it is built.The outcome of the research is a better understanding of how to model machinery, such as the HPGR and the jaw crusher. By developing high fidelity models, insights are gained on how to move between the different modeling domains. The knowledge is useful for studies of circuits, and how to set up optimal controllers. Especially controllers that require models of a specific type or models that have to be fast to simulate

Ultrasonic Positioning System for Electric Road System

Elonroad is a company that is looking into the possibility to charge electric vehicle on road. The conductor implemented on the driveway has a characteristic shape. The scope of this master thesis project is to identify the shape of the conductor and determine the relative position of the vehicle to the conductor using ultrasonic sensors. The goal is to have an update frequency of 30 Hz and a positioning error of maximum 2 cm. During the project a serial system containing 7 ultrasonic modules has been built. The sensor modules are mounted in an array and placed parallel to the road and perpendicular to the vehicles intended direction of travel. The ultrasonic modules are placed with a center distance of 10 cm on the array. A cross-correlation algorithm was implemented to determine the distance to the surface below each of the ultrasonic modules. The method to find the relative position of the vehicle uses a modified convolution algorithm which is proven to work under ideal circumstances. The distance measurement from the modules to ground can differ roughly +/-8 mm, this originates from the wavelength of the 40 kHz ultrasonic signal in air, the +/-8 mm error can, according to simulations give a positioning error of up to 5 cm. Simulations has indicated that +/-4 mm will give a positioning error less than, or equal to, 2 cm. The update frequency is assumed to be around 20 Hz, where the largest part is due to calculation time of the distance to ground. It can be lowered with more effective algorithms or with a more powerful microcontroller.Electric vehicles can charge their batteries on road by connecting to a conductor integrated in the roadway. In this specific case the integrated conductor consists in an elevated structure. This structures location relative the car needs to be tracked to ensure the car stays connected

Development and demonstration of 2D-LIF for studies of mixture preparation in SI engines

Laser-induced fluorescence (LIF) has been developed for visualization of fuel distribution fields in an operating spark-ignition (SI) engine. Since the standard research fuel iso-octane, does not yield a useful LIF signal a fluorescent additive was used. None of the commonly used seeds were found adequate. A seed not commonly used in this context, 3-pentanone, C2H5COC2H5, was chosen due to favorable vaporization characteristics and fluorescent properties. Results from preparatory investigations in the actual engine environment are presented and related laboratory data are discussed. The two-dimensional LIF technique was applied to a spark-ignition engine and the fuel distribution at the ignition time was recorded. The resulting images were processed and converted into fuel/air equivalence ratio using an in situ calibration technique. The processed fuel distribution maps presented a noise level of 10% and a systematic error not exceeding 0.03 fuel/air equivalence units. An increased combustion variability was observed when changing from a homogeneous to an inhomogeneous fuel/air mixture. Correlations of image data to the combustion development indicated that the increased cyclic variability could be largely explained by variations in the mean fuel concentration around the spark gap. The initial flame development therefore seems to be controlled by the average amount of fuel near the spark gap, whereas the actual distribution of the fuel within this volume is of less importance

Managing Stakeholders in A Housing Renovation Project: A teaching case on real estate project management

Stakeholder management is an important task of project managers in housing renovation. Compared with new construction project, a great challenge that a housing renovation project manager faces, is managing the tenants that living before or during the renovation. This paper is a teaching case based on a real housing renovation project, which confronted difficult stakeholder management problems, of a Swedish real estate company between 2009 to 2016. It provides teaching materials that can be used by instructors for helping students to analyse and summarise the lessons learned from a troublesome stakeholder management process and to come up with suggestions that will ensure a smooth implementation of the housing renovation project. The case contains two main parts, namely the case description and teaching notes. It can be used by teachers and trainers, as well as university bachelor students and industrial practitioners in courses and training programs about housing renovation project management

High-Yield of Memory Elements from Carbon Nanotube Field-Effect Transistors with Atomic Layer Deposited Gate Dielectric

Carbon nanotube field-effect transistors (CNT FETs) have been proposed as possible building blocks for future nano-electronics. But a challenge with CNT FETs is that they appear to randomly display varying amounts of hysteresis in their transfer characteristics. The hysteresis is often attributed to charge trapping in the dielectric layer between the nanotube and the gate. This study includes 94 CNT FET samples, providing an unprecedented basis for statistics on the hysteresis seen in five different CNT-gate configurations. We find that the memory effect can be controlled by carefully designing the gate dielectric in nm-thin layers. By using atomic layer depositions (ALD) of HfO$_{2}$ and TiO$_{2}$ in a triple-layer configuration, we achieve the first CNT FETs with consistent and narrowly distributed memory effects in their transfer characteristics.Comment: 6 pages, 3 figures; added one reference, text reformatted with smaller addition

Safety culture and organizational climate in air traffic control

Due to organizational changes in the Swedish air navigation services (ANS), which in extension could impact flight safety, the safety culture (SC), organizational climate (OC), and related areas are monitored. Study locations are the two main air traffic control centers in Sweden and parts of the central ANS office. This paper reports on a first attempt to investigate whether relationships exist between SC and OC. The findings show that such relationships exist

Ilmenite with addition of NiO as oxygen carrier for chemical-looping combustion

The naturally occurring mineral ilmenite, FeTiO3, has been examined as oxygen carrier for chemical-looping combustion. NiO-based particles have been used as an additive, in order to examine if it is possible to utilize the catalytic properties of metallic Ni to facilitate decomposition of hydrocarbons into more reactive combustion intermediates such as CO and H2. Firstly, ilmenite was examined by oxidation and reduction experiments in a batch fluidized-bed reactor. These experiments indicated moderate reactivity between ilmenite and CH4, which was used as reducing gas. However, adding 5 wt.% of NiO-based particles to the ilmenite improved the conversion of CH4 greatly, resulting in an increase in combustion efficiency with a factor of 3. Secondly, 83 h of chemical-looping combustion experiments were conducted in a small circulating fluidized-bed reactor, using ilmenite as oxygen carrier and natural gas as fuel. A wide range of process parameters and different levels of NiO addition were examined. Occasionally, there were problems with the circulation of solids between the air reactor and fuel reactor, but most of the time the experiments worked well. The products were mostly CO2, H2O and unconverted CH4. Adding small amounts of NiO-based particles to the reactor increased the conversion of the fuel considerably. For the base case conducted at 900, the combustion efficiency was 76% for pure ilmenite and 90% for the corresponding experiments with 1 wt.% NiO-based particles added to the reactor. The properties of ilmenite were found to change considerably during operation. Used particles had lower density, were more reactive and more porous than fresh particles. These changes appear to have been physical, and no unexpected chemical phases could be identified