Sökning: "Acoustic radiation"

Visar resultat 21 - 25 av 65 avhandlingar innehållade orden Acoustic radiation.

1. 21. Studies of Phonons and Phase Transitions by Time-Resolved X-ray Diffraction

   Författare :Henrik Enquist; Atomfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; synchrotron radiation; ultrashort pulses; material science; phase transition; X-ray diffraction; phonon; X-ray detector;

   Sammanfattning : When light is used to study structures, the wavelength limits the size of the details that can be resolved. Visible light can be used to investigate structures as small as a micrometre in size. To study smaller structures a shorter wavelength is required. LÄS MER

3. 22. Positron Emission Tomography (PET) Studies in Anxiety Disorders

   Författare :Åsa Michelgård Palmquist; Mats Fredrikson; Lars von Knorring; Hans Ågren; Uppsala universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Positron emission tomography; PET; amygdala; fear; anxiety; anxiety disorders; specific phobia; social phobia; posttraumatic stress disorder; PTSD; regional cerebral blood flow; rCBF; substance P; SP; neurokinin 1 receptor; NK1; GR205171; STAI-S; Psychiatry; Psykiatri; Neurobiology; Neurobiologi; Neuroscience; Neurovetenskap; Experimental brain research; Experimentell hjärnforskning; Molecular neurobiology; Molekylär neurobiologi; Radiation biology; Strålningsbiologi; Neurobiology; Neurobiologi; Neurobiology; Neurobiologi;

   Sammanfattning : Anxiety disorders are very common and the primary feature is abnormal or inappropriate anxiety. Fear and anxiety is often mediated by the amygdala, a brain structure rich in substance P (SP) and neurokinin 1 (NK1) receptors. LÄS MER

4. 23. A Novel Bone Conduction Implant System

   Författare :Hamidreza Taghavi; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sound radiation; amplitude modulation; low-power systems.; bone conduction implant; feedback; bone anchored hearing aid; RF power amplifier; gain headroom; implantable transducer; wireless power and data transmission; RF power and data link;

   Sammanfattning : Bone conduction is the process by which an acoustic signal vibrates the skull bones to stimulate the cochlea. Patients with pure conductive hearing loss, mixed hearing loss, and single sided deafness are sometimes poorly rehabilitated by conventional air conduction hearing aids due to for example the functionality losses in the middle ear. LÄS MER

5. 24. Investigation of acoustic source characterisation and installation effects for small axial fans

   Författare :Per-Olof Berglund; KTH; []
   Nyckelord :axial fan; airborne sound; source characterisation; transmission path analysis; in-duct. Spherical harmonics;

   Sammanfattning : Fans are often used in equipment such as home appliances andelectronic equipment where the margin of profit is small butcustomers demands on a low noise level are high. Therefore,methods for predicting the noise emitted by an applicationincluding one or several fans are desirable in order toimprove, accelerate and reduce the cost of low-noise design. LÄS MER

7. 25. Direction of Arrival Estimation of Wideband Acoustic Wavefields in a Passive Sensing Environment

   Författare :George Mathai; Fredrik Gustafsson; David Lindgren; Linköpings universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : Direction Of Arrival (DOA) estimation has been an active research area for many decades because of its usefulness in many fields, such as wireless communication, navigation, astronomy, surveillance, medicine etc. In DOA estimation, emitted wavefields from unknown sources are measured with the aid of an array of sensors, and this information is then processed to determine various parameters of the sources including the angle between each source and the array. LÄS MER