Experimental study and theoretical modelling of ultrasonic wave propagation in resistance spot welds.

The theoretical and experimental study of resistance spot weld quality has a long history. Since the invention of the method manufacturers are concerned about the means of quality assurance of the joints. One of the most promising current techniques of quality inspection is the real time ultrasonic nondestructive evaluation. In such a system the acoustic signals are sent through the spot weld during welding and then analyzed to predict the size of the future joint. In spite of its purely industrial application and seemingly easy setup the problem involves several complicated mechanisms to be described using a physical-mathematical approach. This thesis is concerned with the development of mathematical models describing thermal dynamics in the system and acoustic wave propagation through it. The analysis of these results helps to understand the ways the system could affect the transmitted signal. The models are compared with experimental observations. Possible applications of the developed simulations are discussed.Dept. of Physics. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2003 .C49. Source: Masters Abstracts International, Volume: 43-01, page: 0224. Adviser: Roman Gr. Maev. Thesis (M.Sc.)--University of Windsor (Canada), 2003

Paraelectric and ferroelectric order in two-state dipolar fluids

Monte Carlo simulations are used to examine cooperative creation of polar state in fluids of two-state particles with nonzero dipole in the excited state. With lowering temperature such systems undergo a second order transition from nonpolar to polar, paraelectric phase. The transition is accompanied by a dielectric anomaly of polarization susceptibility increasing by three orders of magnitude. The paraelectric phase is then followed by formation of a nematic ferroelectric which further freezes into an fcc ferroelectric crystal by a first order transition. A mean-field model of phase transitions is discussed.Comment: 5 pages, 4 figure

Study Of Oxidation Processes In Duck Meat With Application Of Rosemary And Grape Seed Extracts

The substantiation of the expedience of using antioxidants of a natural origin to decelerate oxidation processes in different meat products is an urgent direction of these studies. The prospective way of a solution of the problem of meat products oxidation spoilage is the use of vegetable extracts. The experimental studies of the effective use of the composition of rosemary and grape seed extracts in Peking duck forcemeat at the long storage were realized. Their influence on the dynamics of hydrolytic and peroxide oxidation of forcemeat lipids was studied. The analysis of oxidation secondary products accumulation was realized at the same time.The positive effect of the combined use of rosemary and grape seeds extracts on frozen Peking duck forcemeat was established, the optimal concentration of offered preparations was determined