Resistance spot welding is used frequently as a successful joining method for a variety of work commonly in automotive and other manufacturing processes. Spot weld nugget is generally hidden between two sheets, causing its inspection difficult and expensive. Undersized nuggets, brittle or cracked nuggets, and excessive indentation of electrodes reveals the lack of fusion between the parts that can make the weld sub-standard. Visual inspection, pry testing and physical teardown with chisel and hammer method or a combination of them are being used traditionally. However, this study presents a more effective nondestructive inspection method based upon an ultrasonic pulse-echo technique. The theory of the technique together with the experimental verification are presented and its advantages over the other destructive and nondestructive techniques are considered.

The objectives for the first part of this thesis were to describe changes in oxygen saturation (SpO2) and heart rate (HR) in newly born infants in the delivery room (DR) and to illustrate the changes using centile reference charts. The objective of the second part of the thesis was to investigate whether infants < 29 weeks gestation who receive positive pressure ventilation (PPV), immediately after birth with a T-piece have higher SpO2 measurements at five minutes than infants ventilated with a self inflating bag (SIB). / Study Design. A prospective observational study was used to achieve the first objectives. For the second part of the thesis I coordinated a randomised, controlled trial of two devices used for resuscitation of extremely preterm infants in the DR where the primary outcome measure was SpO2. / Patients and methods. In all studies a Masimo Radical pulse oximeter (PO) was placed on the infant’s right hand/wrist immediately after birth. PO data (oxygen saturation, HR and signal quality) were downloaded every 2 sec and analysed only when the signal had no alarm messages (low IQ signal, low perfusion, sensor off, ambient light). / Results. Observational studies: The dataset to develop the reference range charts included 61,650 data points from 468 infants. Infants had a mean (range) gestational age of 38 (25-42) weeks and birthweight 2970 (625-5135) g. For all 468 infants at one minute the 3rd, 10th, 50th, 90th and 97th centiles were 29%, 39%, 66%, 87% and 92%; at two minutes 34%, 46%, 73%, 91% and 95% and at five minutes 59%, 73%, 89%, 97% and 98%. It took a median of 7.9 (IQR 5.0 to 10) minutes to reach a SpO2 > 90%. SpO2 of preterm infants rose more slowly than that of term infants. At one min the median (IQR) HR was 82 (66 to 138) bpm rising at two min and five min to 151 (112 to 169) bpm and 166 (148 to 176) bpm respectively. In preterm infants, the SpO2 and HR rose more slowly than term infants. / Randomised trial: Forty nine infants were randomly allocated to the T-piece and 50 to the SIB. Ten infants did not receive PPV, 4 (8%) in the T-piece group and 6 (12%) in the SIB group and were not included in the analysis. Forty-one infants received PPV with a T-piece and 39 with a SIB. At 5 minutes after birth there was no significant difference between the mean (SD) SpO2 in the T-piece and SIB groups [50 (31)% vs. 53 (25)%, (p=0.73)]. More T-piece infants received oxygen during DR resuscitation (100% vs. 90%, p=0.04). There was no significant difference between the groups in the use of continuous positive airway pressure (CPAP); endotracheal intubation or administration of surfactant in the DR. Fewer of the T-piece group who left the DR on CPAP were intubated in the first 24 hrs after birth. (7% vs. 23%, p=0.05). / Conclusion. The centile charts developed in this thesis provide a reference range for SpO2 and HR in the first 10 minutes after birth for preterm and term infants. In the randomised trial there was no significant difference in SpO2 at five minutes after birth in extremely preterm infants given PPV with a T-piece or a SIB.

Sleep related breathing disorders in childhood are increasingly recognised as contributors to morbidity as well as suboptimal physical, mental and social development. The associated cost in social and economic terms is clearly significant. Detection and diagnosis of such disorders can be costly and technically difficult. Multi-parameter monitoring like polysomnography is expensive and inappropriate for mass screening or investigations remote from tertiary centres. A simple and non-invasive cardiovascular approach termed pulse transit time (PTT) is useful in determining the status of upper airways during sleep. This approach employs the measurement of the time delay in the arterial pulse pressure wave from the aortic valve of the heart to a peripheral site. PTT has shown promise to provide quantify inspiratory effort in adults with sleep disordered breathing (SDB) and can then be an effective monitoring tool in children. Initial investigations explore the parameters that can confound the PTT measurements of a child. This work provides an estimate of the expected PTT ranges from infancy to childhood. Thereafter, overnight PTT recordings were performed in conjunction with PSG studies to corroborate evidence for its capability in paediatric respiratory studies. The results show that PTT has the ability to identify abnormal respiratory events during sleep. Furthermore, the use of PTT can differentiate the nature of respiratory events as obstructive or central. Technological considerations to improve the robustness of PTT measure to be used not only in cardiorespiratory but also cardiovascular studies on children were also illustrated. Preliminary findings obtained here suggest that the properties of PTT show promise as a predictor for obstructive sleep apnoea. There is a need to bridge the gap of providing quality SDB diagnosis and yet accommodating requirements for a robust screening measure. PTT has demonstrated its suitability and utility as a measure to play a role in the investigation and monitoring of treatment in this area.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 3, 2008) Vita. Includes bibliographical references.

Thesis (Ph.D.)--McMaster University (Canada), 1993. / Source: Dissertation Abstracts International, Volume: 54-12, Section: B, page: 6277. Adviser: T. Timusk.

Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 22, 2009) Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 105-108). Also available on the World Wide Web.

Thesis, M.Phil., University of Hong Kong, 1984. / Also available in print.

Thesis (M.S.)--Florida State University, 2005. / Advisor: Dr. Jie Chang, Florida State University, FAMU-FSU College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed June 9, 2005). Document formatted into pages; contains xiii, 76 pages. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xviii, 224 p.; also includes graphics. Includes bibliographical references (p. 199-211).