Improving Dst index prediction using Kalman filtering techniques

Over the past few decades, short term Dst index prediction using different techniques have been proposed since effects of space weather cause many problems on operational systems on Earth. Using input-output methods, the coupling function between solar wind parameters and Dst index is found to be nonlinear. In practice, observed data have been provided in almost real time but this is very noisy. To address noisy data and nonlinear dynamics, Kalman filtering techniques are used. Furthermore, the measurement noise which is derived from the error between provisional Dst and quick look Dst is found to be non white and modelled using an ARMA structure. Four existing models are chosen and a new model using NARX structure is proposed. Parameter estimation using joint and dual estimation techniques is studied. A comparison between models with Kalman filtering techniques and models alone is made and it is found that Kalman filtering methods can improve prediction performance and reduce prediction error.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Mechanical Properties Enhancement of Dissimilar AA6061-T6 and AA7075-T651 Friction Stir Welds Coupled with Deep Rolling Process

The main purpose of this research was to enhance the mechanical properties of friction stir welds (FSW) in the dissimilar aluminum alloys 6061-T6 and 7075-T651. The welded workpiece has tensile residual stress due to the influence of the thermal conductivity of dissimilar materials, resulting in crack initiation and less fatigue strength. The experiment started from the FSW process using the 2k full factorial with the response surface methodology (RSM) and central composite design (CCD) to investigate three factors. The experiment found that the optimal rotation speed and feed rate values were 979 and 65 mm/min, respectively. Then, the post-weld heat treatment process (PWHT) was applied. Following this, the 2k full factorial was used to investigate four factors involved in the deep rolling process (DR). The experiment found that the optimal deep rolling pressure and deep rolling offset values were 300 bar and 0.2 mm, respectively. Moreover, mechanical property testing was performed with a sequence of four design types of workpieces: FSW, FSW-PWHT, FSW-DR, and FSW-PWHT-DR. It was found that the FSW-PWHT-DR workpiece had an increase in tensile strength of up to 26.29% and increase in fatigue life of up to 129.47% when compared with the FSW workpieces, as well as a maximum compressive residual stress of −414 MPa

การออกแบบระบบให้คำปรึกษาและบริการข้อมูลเทคโนโลยีออนไลน์สำหรับศูนย์คลินิก เทคโนโลยีสถาบันวิจัยและพัฒนามหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร

รายงานวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2563This project, Online Consulting System Design and Technology Information service Project for Clinic Technology of Research and Development Institute, Rajamangala University of Technology Phra Nakhon, aims to design consulting system and online technology information services for Clinic Technology of Research and Development Institute, Rajamangala University of Technology Phra Nakhon. The in-built system facilitates quick communication, get the information, and can deliver technology information on demand in order to respond to the service recipients as quickly as possible. Moreover, it reduces the coordination process and paper usage, able to collect statistics and information as per service recipients need as well as technology and knowledge that are ready to be transferred. The data storage is well-organized by using ASP.NET C #, HTML, Java and Microsoft Sql Server 2012 in system design. The results of the satisfaction evaluation towards the efficiency of the system, from 226 people, found that the overall satisfaction was the highest with the mean at 4.68. This shows that online consulting system and technology information service project for Clinic Technology of Research and Development Institute, Rajamangala University of Technology Phra Nakhon can be used to provide consulting and technology information services to service recipients.Rajamangala University of Technology Phra Nakho