The aim of the present work is to find out a method for ultrasonic testing of composite fiber-reinforced multilayer polymer materials.

No description available.

No description available.

Background and aims: It is known that smooth muscle possesses substantial mechanical plasticity in that it is able to adapt to large changes in length without compromising its ability to generate force. It is believed that structural malleability of the contractile apparatus underlies this plasticity. There is strong evidence suggesting that myosin thick filaments of the muscle are relatively labile and their length in vivo is determined by the equilibrium between monomeric and filamentous myosin. The equilibrium in turn is governed by the state of phosphorylation of the 20-kD regulatory myosin light chain (MLC20, or RLC). It is known that phosphorylation of the myosin light chain favors formation of the filaments; it is not known how the light chain phosphorylation affects the lability of the filaments. The major aim of this thesis was to measure the mechanical integrity of the filaments formed from purified myosin molecules from bovine airway smooth muscle, and to determine whether the integrity was influenced by phosphorylation of the myosin light chain. Methods: Myosin was purified from bovine trachealis to form filaments, in ATP containing zero-calcium solution during a slow dialysis that gradually reduced the ionic strength. Sufficient myosin light chain kinase and phosphatase, as well as calmodulin, were retained after the myosin purification and this enabled phosphorylation of RLC within 20-40 s after addition of calcium to the filament suspension. The phosphorylated and non-phosphorylated filaments were then partially disassembled by ultrasonification. The extent of filament disintegration was visualized and quantified by atomic force microscopy. Results: RLC phosphorylation reduced the diameter of the filaments and rendered the filaments more resistant to ultrasonic agitation. Electron microscopy revealed a similar reduction in filament diameter in intact smooth muscle when the cells were activated. Conclusion: Our results suggest that RLC phosphorylation is a key regulatory step in modifying the structural properties of myosin filaments in smooth muscle, where formation and dissolution of the filaments are required in the cells’ adaptation to different cell length.

Presented in this thesis are two studies that apply nondestructive testing methods to civil engineering problems. The first study examines the relationship between the small-strain and large-strain properties of exhumed cast iron water pipes. Nondestructive and destructive testing programs were performed on eight pipes varying in age from 40 to 130 years. New applications of frequency domain analysis techniques including Fourier and wavelet transforms of ultrasonic pulse velocity measurements are presented. The effects of Lamb wave propagation on the ultrasonic testing results are investigated. Microstructure evaluation revealed two different types of cast iron within the pipes sampled: grey cast iron and ductile iron. A low correlation between wave propagation and large-strain measurements was observed. However, the wave velocities were consistently different between ductile and grey cast iron pipes (14% to 18% difference). Lamb waves were found to contribute significantly to the frequency content of the ultrasonic signals possibly resulting in the poor correlations observed. Therefore, correlations between wave velocities and large strain properties obtained using samples from exhumed water pipes must be used with caution in the condition assessment of aged water pipes especially for grey cast iron pipes. The second study presented in this thesis was performed to evaluate the effectiveness of three geophysical methods for geotechnical site characterization in swamps and environmentally sensitive wetland areas. The geophysical methods evaluated were electrical resistivity imaging (ERI), seismic refraction (SR), and multiple-channel analysis of surface waves (MASW). The geophysical test results were verified against the results from borehole and CPT logs. The ERI results were best for determining the depth to the glacial till. The SR results overestimated the depth to the till because of the presence of a stiffness reversal. The MASW results predicted the depth to the refusal till layer less accurately than the ERI method. However, this method was able to detect the three distinct layers above the till. These methods can be used as a basis for further development to optimize a procedure to reduce the number of boreholes required for conventional site investigations in areas that are environmentally sensitive or where access is restricted.

Darbo tikslas: Vilniaus pedagoginio universiteto ultragarsinių mechanizmų laboratorijoje sukurtų ultragarsinių keitiklių kompiuterinis modeliavimas ir jų parametrų optimizavimas. Uždaviniai:  Taikant AutoCAD (Solid Works) ir ANSYS programas, sukurti mikro-variklio geometrinį ir matematinį modelius;  Nustatyti duoto pjezovariklio pagrindinius parametrus;  Atlikti ultragarsinės virpesių sistemos (UVS) dinaminę analizę ir nustatyti darbinio taško judėjimo trajektoriją, esant harmoniniam žadinimui.  Optimizuoti darbinio taško trajektoriją, priklausomai nuo išorinių parametrų. Rezultatai ir išvados Sudaryti pjezokeitiklio geometrinis ir matematinis modeliai. Ištirtas ultragarsinių virpesių sistemų išėjimo grandies taškų judėjimo elipsine trajektorija formavimo principas. Išanalizuotos “ultragarsinio keitiklio” ultragarsinių virpesių sistemų bei jų koncentratorių savosios virpesių formos ir savieji rezonansiniai dažniai. Atlikta UVS dinaminė analizė ir nustatyta darbinio taško judėjimo trajektorija esant harmoniniam virpesių žadinimui. Nustatyti ultragarsinės virpesių sistemos (UVS) sužadinimo parametrai, prie kurių gaunama maksimali darbinio taško judėjimo trajektorija. / The purpose of this thesis: Computerised modelling of ultrasound converters created at the ultrasound laboratory of Vilnius Pedagogical University and optimisation of their parameters. Goals:  To create the geometric and mathematic models of micro-engine applying AutoCAD (Solid Works) and ANSYS programs;  To establish the main parameters of the given piezoengine;  To perform the dynamic analysis of the ultrasound vibrations system (UVS) and establish the trajectory of the operating point, when the harmonic excitation is present.  To optimize, depending on the external parameters, the trajectory of the operating point. Results and conclusions The geometric and mathematic models of piezoconverter have been established. The principle of formation of movement along the ellipse trajectory of ultrasound vibrations systems outlet chain’s points has been investigated. The very own vibrations forms and the very own resonant frequencies of “the ultrasound converter’s” ultrasound vibrations systems and their concentrators have been analysed. UVS dynamic analysis has been performed and the operating point’s movement trajectory, when the harmonic vibrations excitation is present, has been established. The ultrasound vibrations systems (UVS) excitation parameters, at which the peak trajectory of the operating point is obtained, have been established.

Independent mobility is critical to quality of life for people of all ages, and impaired mobility leaves one with both physical and mental disadvantages. Unfortunately, there are some individuals unable to operate an electric wheelchair due to physical, perceptual, or cognitive deficits. The prime objective of this research was to develop a prototype system which can provide mobility assistant to individuals who would otherwise find it difficult or impossible to operate a power wheelchair. To accomplish this goal, a prototype system consisting of several components including an embedded microcontroller and multiple sensors has been designed which can be added to a standard power wheelchair and make it smart. The control system algorithm designed for this prototype model is based on the fuzzy logic control theory and its main purpose is to augment the user ability to navigate the wheelchair and will provide a safe and comfortable journey to the user.

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No description available.

Dissertation submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic Durban University of Technology, 2009 / Aim: To investigate the effect of therapeutic and sham ultrasound on radial artery blood flow (m.s-1) and radial arterial lumen diameter (mm). Subjects: Fifty healthy asymptomatic volunteers between the ages of 18-38 years. Methodology: The subjects were randomly allocated into one of five intervention groups (A-E). Group A received continuous ultrasound at 0.2 W.cm-² for 5 minutes, Group B received pulse ultrasound at 0.2 W.cm-² for 5 minutes, Group C received continuous ultrasound at 1.5 W.cm-² for 5 minutes, Group D received pulse ultrasound at 1.5 W.cm-² for 5 minutes and Group E received sham ultrasound at 0 W.cm-² for 5 minutes. Baseline radial artery blood flow (m.s-1) and radial artery lumen diameter (mm) readings were taken prior to the commencement of the therapeutic or sham ultrasound application using a Doppler ultrasound. At four minutes of application (during the therapeutic or sham ultrasound application), another set of blood flow and arterial lumen diameter measurements were taken. The final blood flow and arterial lumen diameter measurements were taken one minute after the therapeutic or sham ultrasound application was stopped. Results: The mean (± SD) radial artery blood flow and radial artery lumen diameter at baseline was 0.197 (± 0.060) m.s-1 and 2.4 (± 0.6) mm respectively. In Group A, the mean (± SD) radial artery blood flow during ultrasound application and one-minute after ultrasound application was 0.193 (± 0.070) m.s-1 and 0.179 (± 0.073) m.s-1 respectively. The mean (± SD) radial artery lumen diameter in Group A at the two time intervals was 2.2 (± 0.5) mm and 2.2 (± 0.3) mm respectively. In Group B, the mean (± SD) radial artery blood flow during ultrasound application and one-minute after ultrasound application was 0.187 (± 0.067) m.s-1 and 0.195 (± 0.041) m.s-1 respectively. The mean (± SD) radial artery lumen diameter in Group B at the two time intervals was 2.4 (± 0.4) mm and 2.3 (± 0.5) mm respectively. In Group C, the mean (± SD) radial artery blood flow during ultrasound application and one-minute after ultrasound application was 0.225 (± 0.088) m.s-1 and 0.186 (± 0.071) m.s-1 respectively. The mean (± SD) radial artery lumen diameter in Group C at the two time intervals was 2.4 (± 0.7) mm and 2.7 (± 0.8) mm respectively. In Group D, the mean (± SD) radial artery blood flow during ultrasound application and one-minute after ultrasound application was 0.215 (± 0.080) m.s-1 and 0.200 (± 0.081) m.s-1 respectively. The mean (± SD) radial artery lumen diameter in Group iv D at the two time intervals was 2.4 (± 0.8) mm and 2.4 (± 0.7) mm respectively. In Group E, the mean (± SD) radial artery blood flow during ultrasound application and one-minute after ultrasound application was 0.200 (± 0.067) m.s-1 and 0.182 (± 0.075) m.s-1 respectively. The mean (± SD) radial artery lumen diameter in Group E at the two time intervals was 2.5 (± 0.7) mm and 2.3 (± 0.5) mm respectively. There was no significant change in radial artery blood flow and radial artery lumen diameter over time in any individual group or between groups (p > 0.05; repeated measures ANOVA). There was an overall weak positive correlation between radial artery blood flow and radial artery lumen diameter at baseline (r = 0.508), during (r = 0.541) and after (r = 0.532) the therapeutic or sham ultrasound application. Conclusion: The results of this study showed that continuous, pulse or sham ultrasound had no significant effect on radial artery blood flow and radial artery lumen diameter. Furthermore, active ultrasound (continuous and pulse) was not superior to sham ultrasound in significantly affecting blood flow in a muscular artery.