Distributed model predictive control of steam/water loop in large scale ships

In modern steam power plants, the ever-increasing complexity requires great reliability and flexibility of the control system. Hence, in this paper, the feasibility of a distributed model predictive control (DiMPC) strategy with an extended prediction self-adaptive control (EPSAC) framework is studied, in which the multiple controllers allow each sub-loop to have its own requirement flexibility. Meanwhile, the model predictive control can guarantee a good performance for the system with constraints. The performance is compared against a decentralized model predictive control (DeMPC) and a centralized model predictive control (CMPC). In order to improve the computing speed, a multiple objective model predictive control (MOMPC) is proposed. For the stability of the control system, the convergence of the DiMPC is discussed. Simulation tests are performed on the five different sub-loops of steam/water loop. The results indicate that the DiMPC may achieve similar performance as CMPC while outperforming the DeMPC method

Hovering-type AUV의 경로추종을 위한 제어기 설계 및 실해역 실험에 관한 연구

AUV replacing humans and performing works in deep sea where humans are hard to work is actively developed. AUVs are various on purpose, but among them, Hovering-type AUV can perform works by keeping its position and posture under water. Studies about AUV are being performed domestically, but comparing to other counties, technologies fall behind. So it is needed to accept outside technologies that already reached commercialization and to secure technical skills by developing navigation algorithm. In this thesis, performances of AUV were verified by making Hovering-type AUV test-bed and designing various controllers. Developed AUV can control 4DOF motion, using 2 horizontal thrusters and 2 vertical thrusters. Prior to field test, 6DOF equations of motion is developed, simulation program is constructed by using Matlab/Simulink, and essential motion performance of designed vehicle is verified. Besides, PID controller and Fuzzy PID controller are designed for carrying out their missions, and performance of the controllers is verified by simulation. Tests are performed in the field to verify motion performance of the AUV, and the way-point tracking is performed by PID and Fuzzy PID controller to the vehicle. It results in confirming appropriate control performance under current disturbances. Result graphs of experiments were showed, and by analyzing those, performances of controllers were verified.CHAPTER 1 INTRODUCTION 1.1 Background 1 CHAPTER 2 HOVERING-TYPE AUV’S HARDWARE & SENSORS 2.1 Hardware of ‘OCTAGON’ 4 2.2 Sensors 8 CHAPTER 3 AUV’S MATHEMATICAL MODEL & DESIGN CONTROLLER 3.1 Coordinate system setting & AUV’s mathematical model 13 3.2 Design controller 17 3.2.1 Design PID controller 18 3.2.2 Design Fuzzy PID controller 20 3.3 Simulation results 27 CHAPTER 4 FIELD TESTS 4.1 PID control 32 4.1.1 Depth control 32 4.1.2 Heading control 33 4.1.3 Way-point control 34 4.2 Fuzzy PID control 38 4.2.1 Depth control 38 4.2.2 Heading control 41 4.2.3 way-point control 44 CHAPTER 5 CONCLUSION 48 References 5

Decision making process in keystroke dynamics

Computer system intrusion often happens nowadays. Various methods have been introduced to reduce and prevent these intrusions, however no method was 100% proven to be effective. Therefore, to improve the computer’s security, this writing will explain the application of KD in the application system. The effectiveness of KD could not guarantee one hundred percent to prevent the computer intrusion, but it can be used as a second level of security after the login page in the application system. The pattern and time taken while typing by an individual is the core for the second level of security check after the login page. This writing will elaborate and conclude past studies related to KD on the aspects of decisionmaking process. Various methods of processing KD data that have been used are listed and the results of the study are compared. The results of this writing are expected to help new researchers in the process of evaluating KD data

Effect of strain rates on tensile properties and fracture toughness determination of extruded Mg-Al-Zn alloys

Extruded Mg-Al-Zn alloy is a lightweight and high strength magnesium alloy that is becoming a preferred material to be used as a structural component in automobiles. During a crash event, an automobile structure is subjected to dynamic loading. The magnesium alloy structures must be able to maintain its integrity and provide adequate protection in survivable crashes. Besides static tensile properties, tensile properties at high strain rates of extruded magnesium alloys and their fracture behaviour are some of the important parameters to be considered in design in ensuring the durability and reliability of automobile structures. In this study, the effect of strain rates on tensile properties and work hardening behaviour were evaluated for extruded Mg-Al-Zn alloys. Further, the fracture behaviour at different loading rates and the effect of temperature on fracture toughness of Mg-Al-Zn alloys were investigated. The extruded Mg-Al-Zn alloys used in this study were AZ61 and AZ31 magnesium alloys. Tensile tests under low and high strain rates were carried out using a universal testing machine and high strain rate tensile tester, respectively. The high strain rate tensile tester was designed and fabricated in-house to fulfil the requirement of tensile test under high strain rate ranging from 100 to 600 s -1 . Work hardening behaviour for low strain rate tensile specimen was determined by referring to the ASTM E646. To obtain the fracture behaviour of both alloys at different loading rates, three-point bending fracture test was conducted on pre-cracked specimens. Standard test methods i.e. ASTM E1820 and JSME S001 were referred to determine the elastic-plastic fracture toughness JIC value of AZ31 and AZ61 alloys. The JIC value obtained were then used as a standard reference value to identify a proper groove depth of a single side-grooved specimen. The side-groove depths evaluated were 25%, 35% and 50%. The proper depth of the side-grooves is confirmed after the J value obtained from the side-grooved specimen test method is identical to the JIC value that of the standard test method. The side-grooved specimen with proper groove depth was then used to determine the JIC value of AZ61 alloy at high temperature. From the results, the tensile strengths were gradually increased with increasing strain rates. However, at above 200 s-1 , the tensile strength increased significantly to more than 600 to 800 MPa. In addition, the work hardening rate for AZ61 was found higher compared to that of AZ31. Both alloys exhibited significant elastic-plastic fracture behaviour at different loading rates. It was found that 50% side-grooves depth is appropriate enough to produce valid JIC value using a single specimen. This finding is very useful especially in determining JIC value in a condition where standard multiple specimen test method is difficult to be conducted such as in high temperature environment. The JIC values of AZ31 and AZ61 at room temperature were 19 and 25 kJ/m2 , respectively. Meanwhile, the JIC value of AZ61 at 150 °C was found twice higher than the JIC value at room temperature

Internet based data logging and supervisory control of boiler drum level using LabVIEW

This work describes a framework of a Internet based data logging and supervisory control of boiler drum level system. The design and implementation of this process is done by the LabVIEW software. The data of the process variables (Temperature and Level) from the boiler system need to be logged in a database for further analysis and supervisory control. A LabVIEW based data logging and supervisory control program simulates the process and the generated data are logged in to the database as text file with proper indication about the status of the process variable (normal or not normal. Three different types of boiler drum level control system are designed in the Circuit Design and Simulation toolkit of LabVIEW. This work provides the knowledge about the Fuzzy Adaptive PID Controller and the various PID controller design methods such as Zeigler-Nichol method, Tyreus-Luyben method, Internal Model Control (IMC). Comparative study is made on the performance of the PID and Fuzzy Adaptive PID controller for better control system design. The internet plays a significant and vital role in the real time control and monitoring of the industrial process. Internet based system control and monitor the plant system remotely from anywhere without any limitation to any geographical region. Internet based boiler control system is developed by a Web Publishing tool in LabVIEW. The use of internet as a communication medium provides the flexible and cost- effective solution. Now, to analyse the performance of boiler drum level control system, Internet based data logging and supervisory control system is designed. Hence, anyone can control and monitor the boiler plant globally

Extruder for food product (otak–otak) with heater and roll cutter

Food extrusion is a form of extrusion used in food industries. It is a process by which a set of mixed ingredients are forced through an opening in a perforated plate or die with a design specific to the food, and is then cut to a specified size by blades [1]. Summary of the invention principal objects of the present invention are to provide a machine capable of continuously producing food products having an’ extruded filler material of meat or similarity and an extruded outer covering of a moldable food product, such as otak-otak, that completely envelopes the filler material

Control of proton exchange membrane fuel cell based on fuzzy logic

This paper presents a control strategy suitable for hydrogen/air proton-exchange membrane fuel cells (PEMFCs), based on the process modeling using fuzzy logic. The control approach is tested using a PEMFC stack consisting of 32 cells with parallel channels. An optimal fuzzy-PI controller is designed to mainly control the hydrogen and air/oxygen mass flows, and auxiliary variables such as the temperature, pressure, humidity of the membrane, and proportion of stoichiometry. The fuzzy logic controller possesses many advantages over the PID controllers, such as a higher performance/cost ratio. It is shown experimentally that the optimal fuzzy-PI controller can improve the voltage and current performance of the system when the load changes

Computational intelligence techniques for HVAC systems: a review

Buildings are responsible for 40% of global energy use and contribute towards 30% of the total CO2 emissions. The drive to reduce energy use and associated greenhouse gas emissions from buildings has acted as a catalyst in the development of advanced computational methods for energy efficient design, management and control of buildings and systems. Heating, ventilation and air conditioning (HVAC) systems are the major source of energy consumption in buildings and an ideal candidate for substantial reductions in energy demand. Significant advances have been made in the past decades on the application of computational intelligence (CI) techniques for HVAC design, control, management, optimization, and fault detection and diagnosis. This article presents a comprehensive and critical review on the theory and applications of CI techniques for prediction, optimization, control and diagnosis of HVAC systems.The analysis of trends reveals the minimization of energy consumption was the key optimization objective in the reviewed research, closely followed by the optimization of thermal comfort, indoor air quality and occupant preferences. Hardcoded Matlab program was the most widely used simulation tool, followed by TRNSYS, EnergyPlus, DOE–2, HVACSim+ and ESP–r. Metaheuristic algorithms were the preferred CI method for solving HVAC related problems and in particular genetic algorithms were applied in most of the studies. Despite the low number of studies focussing on MAS, as compared to the other CI techniques, interest in the technique is increasing due to their ability of dividing and conquering an HVAC optimization problem with enhanced overall performance. The paper also identifies prospective future advancements and research directions

"Ann" artifical neural networks and fuzzy logic models for cooling load prediction

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2005Includes bibliographical references (leaves: 44-45)Text in English; Abstract: Turkish and Englishx, 45 leavesIn this thesis Artificial Neural Networks (ANN) and fuzzy logic models of the building energy use predictions were created. Data collected from a Hawaian 42 storey commercial building chiller plant power consumption and independent hourly climate data were obtained from the National Climate Data Center of the USA. These data were used in both ANN and the fuzzy model setting up and testing. The tropical climate data consisted of dry bulb temperature, wet bulb temperature, dew point temperature, relative humidity percentage, wind speed and wind direction.Both input variables and the output variable of the central chiller plant power consumption were fuzzified, and fuzzy membership functions were employed. The Mamdani fuzzy rules (32 rule) in If .Then format with the centre of gravity (COG; centroid) defuzzification were employed. The average percentage error levels in the fuzzy model and the ANN model were end up with 11.6% (R2.0.88) and 10.3% (R2.0.87), respectively. The fuzzy model is successfully presented for predicting chiller plant energy use in tropical climates with small seasonal and daily variations that makes this fuzzy model