There is strong interest in the use of small low-cost highly sensitive magnetic field sensors for applications (such as small memory and biomedical devices) requiring weak field measurements. Among weak-field sensors, the magneto-impedance (MI) sensor has demonstrated an absolute resolution on the order of 10-11 T. The MI effect is a sensitive realignment of a periodic magnetization in response to an external magnetic field within small ferromagnetic structures. However, design of MI sensors has relied primarily on trial and error experimental methods along with decoupled models that separate the micromagnetic and classical electromagnetic equations describing the MI effect. To offer a basis for more cost-effective designs, this thesis research presentation begins with a general formulation describing MI sensors, which relaxes assumptions commonly made leading to decoupling. The coupled set of nonlinear equations is solved numerically using an efficient meshless method in a point collocation formulation. For the problem considered, the chosen method is shown to offer advantages over alternative methods including the finite element method. In the case of time, projection methods are used to stabilize the time discretization algorithm while quasi-Newton methods (nonlinear solver) are shown to be more computationally efficient, as well. Specifically, solutions for two MI sensor element geometries are presented, which were validated against published experimental data. While the examples illustrated here are for MI sensors, the approach presented can also be extended to other weak-field sensors like fluxgate and Hall effect sensors.

How important is the player???s vocal tract in clarinet and saxophone performance? Acoustician???s opinions have ranged from ???negligible??? [Backus (1985), JASA 78, 17] to ???vocal tract resonance frequencies must match the frequency of the required notes??? [Clinch et al. (1982), Acustica 50, 280]. Musicians??? opinions are similarly varied. To understand how the tract-reed-bore system interacts, acoustical measurements of performers??? vocal tracts during playing were made using measurement heads mounted in the mouthpieces of a clarinet and a tenor saxophone. Acoustic impedance spectra of the tenor and soprano saxophone bores were also measured for all standard fingerings, and some others. For fingerings high in the tenor saxophone???s second register, bore impedance peaks downstream decrease with increasing pitch. Above the first 2.7 octaves, peak values fall below 30 MPa.s.m-3 and this ends the standard range available to amateurs. To play the higher altissimo notes, experts produced strong vocal tract resonances upstream with impedances 10-40 MPa.s.m-3 tuned to sound the desired note. While expert saxophonists adjust their vocal tract thus for altissimo playing, inexperienced players do not, and consequently cannot produce these notes. The smoothly rising clarinet glissando solo opening Gershwin???s Rhapsody in Blue was also investigated. Partially uncovering an open finger-hole smoothly raises clarinet resonances in the lower register, allowing continuous increases in playing pitch. When pitch bending in the second (clarino) register, experienced players produced strong tract resonances with impedances up to 60 MPa.s.m-3, comparable in magnitude with those of the clarinet bore (40-50 MPa.s.m-3). Thus during the glissando, sounding pitch is controlled by smoothly varying a strong resonance in the player???s vocal tract. The phase of the reed impedance is shown to make downwards pitch bending easier than upwards. Similar vocal tract adjustments were observed on the clarinet and saxophone for other advanced techniques such as bugling and multiphonic selection. During normal playing, although experienced players produced vocal tract impedance peaks with only moderate magnitude, these peaks were adjusted systematically to frequencies about 150 Hz higher than the sounding pitch (determined by strong bore resonances). This strategy may avoid the effects of small unwanted tract-bore interactions on sounding pitch.

Thesis (Ph. D.)--Ohio University, March, 2000. / Title from PDF t.p.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 8 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (p.43).

Thesis (M.Sc.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on Apr. 13, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Electrical & Computer Engineering, University of Alberta. Includes bibliographical references.

Thesis (M. Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 44-48).

Thesis (M.S.)--Michigan State University. Dept. of Electrical and Computer Engineering, 2008. / "Advisor, Dr. Leo Kempel"--Acknowledgments. Title from PDF t.p. (viewed on Aug. 5, 2009) Includes bibliographical references (p. 167-168). Also issued in print.