Sökning: "directivity"
Visar resultat 1 - 5 av 30 avhandlingar innehållade ordet directivity.
1. On the Directivity of Railway Noise Sources
Sammanfattning : This dissertation deals with the directivity of railway noise. The directivity of railway noise is of particular importance when we have high-rise buildings close to the track, tunnel openings, partial barriers, or when we calculate the maximum sound pressure level during a pass-by based on the sound power level of the different sub-sources of a train. LÄS MER
2. Applicable directivity description of railway noise sources
Sammanfattning : For a sound source, directivity is an important parameter to specify. This parameter also reflects the physical feature of the sound generation mechanism. For example, turbulence sound is of quadrupole directivity whilst fluid-structure interaction often induces a sound of dipole characteristic. LÄS MER
3. Antenna Limitations and Q-factor Trade-off between Parameters, Steps towards Optimal Antenna Design
Sammanfattning : Sub-wavelength antennas have become ubiquitous in essential devices, such as mobile phones, sensors, Internet of things (IoT) and machine to machine (M2M) communication devices. Such antennas are often embedded as a small part of the device chassis or their circuit-boards. LÄS MER
4. Source analysis of multiplet earthquakes (two case studies in Iran)
Sammanfattning : Multiplet earthquakes are large earthquakes of similar magnitude which occur close in time in the same limited geographical area. They are not common but they considerably increase the potential hazard in the area in which they occur. LÄS MER
5. Topology optimization for acoustic wave propagation problems
Sammanfattning : The aim of this study is to develop numerical techniques for the analysis and optimization of acoustic horns for time harmonic wave propagation. An acoustic horn may be viewed as an impedance transformer, designed to give an impedance matching between the feeding waveguide and the surrounding air. LÄS MER