This project aims to design and develop hydro jet which is integrated to Electric motor, whichis limited to run at 70% PWM. Which limits the efficiency of the system, to make an efficientsystem, hydro jet parameters are not defined which are desired to be defined by design fourimpellors for basic Radinn G2x Jet Pack design. The impellors will be four expected points inHydro Jet and final impellor is assumed to lie between these design points, to find the finalspecifications of the hydro jet, the hydro jet will be designed, using computational fluiddynamics they will be analysed. After analysis, they will be manufactured and tested in poolfacility where MGM controller will be used to measure the numerical data from electric circuitwhich powers the system to analyse the performance parameters to finalize the validity of 100% PWM. Microsoft Excel is used to calculate the Hydro Jet Geometric parameters, which areused in Solid Works, where parametric modelling is used to design impellors based ongeometric parameters calculated in Excel. Using Computational fluid dynamics hydro jetperformance is simulated and analysed. To validate the design further, prototypes aremanufactured and tested using workshop pool testing facility using MGM software. As a result,four hydro jet points are calculated, analysed and tested, four pumps are designed for specificflow rate, velocity and torque is calculated for four hydro jets. They are calculated and verifiedusing computational fluid dynamics, as a result flow rate, velocity and torques are calculatedfor all four hydro jets. Four impellors are manufactured and then tested in Radinn work shopand as a result current, power and rpm of the hydro jets are measured using MGM software.From power, rpm and current the torque can be calculated, while rpm is compared againstpredicted computational fluid dynamics results. The results from this project is limited toRadinn G2x jet pack, motor and other parts of the hydro jet’s Jet pack are standard parts

This Licentiate is about Whole Body Vibrations and focuses on transient vibrations with human's discomfort and motion assessment. Whole Body Vibrations occurs when a body is in contact with a vibrating surface. Whole Body Vibrations is a major problem in terrain vehicle, which affects both the physiological and psychological health and discomfort. The first study, Paper A, focus on the prediction of vibration discomfort based on r.m.s.-values in z-direction of seat. In the case of individual results, the correlation coefficient was 0.54. Based on averages for each test condition, the correlation coefficient was 0.93. Study in Paper B focus on the prediction of vibration discomfort and perceived motions. By analysis of vibration values in one-third octave bands of x-direction in the top of the seat backrest, pitch motion and vertical motions in seat, pitch alone with variable length was found to give best correlation with the vector sum of perceived motions (r=0.677). Surprisingly, one-third-octave band higher than 50Hz give a high contribution to the prediction of perceived motions. One of the background variables, "Length of driver", was found to have a statistically significant effect on perceived motions. Tall driver perceived less motion than short drivers. In Paper C, focus on evaluating the effect of two seat design (sliding and fixed) in minimizing the discomfort from transient vibrations. Results showed that sliding seat is superior in attenuating vibration that contains transient vibration in horizontal direction. Sliding seat was perceived to give less overall and low back discomfort compared to fixed seat. / Godkänd; 2002; 20070224 (ysko)

Godkänd; 1998; 20070404 (ysko)

The goal of the Turbine 99 Draft Tube experiments is to provide extensive experimental data on a well-defined sharp-heel draft-tube flow. The data bank has served as calibration data for the simulation challenge presented by the Turbine 99 workshop in Porjus in June 1999. This thesis gives some background on draft-tube flows in general and discusses in some detail the parameters and flow conditions relevant to the Turbine 99 draft tube. Some comments on the research and development conducted so far in the project and future plans are given at the end. In the three accompanying papers, details of the developments and the scientific results are presented: Paper 1. Presents the scope of the work and some initial results from the measurements Paper 2. Discusses the quality of the measurements Paper 3. Presents some of the results from the measurements / Godkänd; 2000; 20070318 (ysko)

Impact sound insulation is one of the most important aspects when assessing sound insulation of floor constructions in buildings. For assessing the impact sound insulation of aconstruction, a standard tapping machine is used as a sound source. However, the use of the current standard tapping machine has been criticised, especially with regard to measurement of wooden joist floors since the noise spectrum generated by a tapping machine differs from the spectrum generated by actual footfall. There are insufficient low frequency components in the noise spectrum produced by the tapping machine and it does not, therefore, accurately reflect low frequency noise from the construction.Reduce impact sound level from wooden joist floors are the main object of our study. It is important to be able to predict the sound insulation properties of wooden joist constructions at the design stage. To reduce the noise level in the receiving room, the input power transmitted through the construction must be estimated where the appropriate sound- and vibration-insulation can be designed.This study has investigated the waveform and frequency spectra of human footfall (walking, rum- ingand jumping); of the dropping of sand balls, sand bags and tires; and of the standard tapping machine. The impact sound power radiation from a wooden joist construction while applying different impact sources, such as actual footfall and the standard tapping machine, have also been studied.Research was also carried out regarding the development of a practical impact sound insulation calculation method for wooden joist floor constructions. The characteristics with regard to mechanical properties of floor construction was calculated using the impedance method. The impact sound level inside the sound receiving room was determined. The method developed can predict the basic performance of the wooden floor structure when excited by impact sounds. / Godkänd; 1995; 20070108 (biem)

Godkänd; 1996; 20080328 (ysko)

The technology for solar cars participating in the Bridgestone World Solar Challenge is constantly evolving. Teams from other universities are implementing innovative solutions in order to be a top contender in the event. JU Solar Team, the representatives for Jönköping University, are looking into applying wheel enclosures inside the body of the solar car, to improve the aerodynamics even further. Thus, the study will investigate how to integrate this component by using methods of design, fluid simulations and concept generation. In this case we are evaluating the effects of using enclosed wheels with the model from the 2019 solar car by JU Solar Team. The purpose of this is to generate empirical value for upcoming generations that will compete in the challenge. The study is built around the 2019 solar car with its dimensions and modules, this include; the wheel suspension, the car body, steering angle, wheel and rim. Simulations are performed with and without enclosed wheels, and stationary wheels and rotating wheels. Wheel rotation and fluid speed are inherited from the driving speed of 72 km/h. Models were simplified during simulations to save computational time.  The results show that wheel enclosures improve the aerodynamics of a solar car. With this simulation configuration and the fourth developed concept, an improvement of 8.22% was achieved.  The study is limited to models being simplified and basic simulations. The research found facilitates possible further investigation for wheel enclosures: manufacturing method, materials and strength evaluation.

This dissertation is concerned with aspects of the newly-proposed approach to nonlinear acoustics in which the Lagrangian description of gas motion is followed. It contains a systematic survey of the approach which leads to the so-called dynamic piston problem. Then new situations regarding the piston problem are studied. These situations cover cases of varying applied pressure and results concerning the formation of shock discontinuities are presented. / Dissertation (MSc)--University of Pretoria, 2013. / Mathematics and Applied Mathematics / unrestricted

Shock wave lithotripsy is the preferred treatment modality for kidney stones in the United States. Despite clinical use for over twenty-five years, the mechanisms of stone fragmentation are still under debate. A piezoelectric array was employed to examine the effect of waveform shape and pressure distribution on stone fragmentation in lithotripsy. The array consisted of 170 elements placed on the inner surface of a 15 cm-radius spherical cap. Each element was driven independently using a 170 individual pulsers, each capable of generating 1.2 kV. The acoustic field was characterized using a fiber optic probe hydrophone with a bandwidth of 30 MHz and a spatial resolution of 100 μm. When all elements were driven simultaneously, the focal waveform was a shock wave with peak pressures p+ =65±3MPa and p−=−16±2MPa and the −6 dB focal region was 13 mm long and 2 mm wide. The delay for each element was the only control parameter for customizing the acoustic field and waveform shape, which was done with the aim of investigating the hypothesized mechanisms of stone fragmentation such as spallation, shear, squeezing, and cavitation. The acoustic field customization was achieved by employing the angular spectrum approach for modeling the forward wave propagation and regression of least square errors to determine the optimal set of delays. Results from the acoustic field customization routine and its implications on stone fragmentation will be discussed. / National Institutes of Health DK043881

In this dissertation, we present two parallelized 3D simulation techniques for three-dimensional acoustic and elastic wave propagation based on the finite integration technique. We demonstrate their usefulness in solving real-world problems with examples in the three very different areas of nondestructive evaluation, medical imaging, and security screening. More precisely, these include concealed weapons detection, periodontal ultrasography, and guided wave inspection of complex piping systems. We have employed these simulation methods to study complex wave phenomena and to develop and test a variety of signal processing and hardware configurations. Simulation results are compared to experimental measurements to confirm the accuracy of the parallel simulation methods.