The quality of atomic force microscope (AFM) data strongly depends on scan and controller parameters. Data artifacts can result from poor dynamic response of the instrument. In order to achieve reliable data, dynamic interactions between AFM components need to be well understood and controlled. In this paper we present a summary of our work in this direction. It includes models for the probe-sample interaction, scanner lateral and longitudinal dynamics, scanner creep, and cantilever dynamics. The models were used to study the effect of scan parameters on the system dynamics. Simulation results for both frequency response and imaging were presented. Experimental results were given supporting the simulations and demonstrating the competence of the models. The results within will be used to develop algorithms that allow automated choice of key system parameters, guaranteeing reliable and artifact-free data for any given operating condition (sample, cantilever, environment). Consequently, expanding the AFM capabilities and permitting its use in a wider range of applications. / Singapore-MIT Alliance (SMA)

We report upon an experimental study of internal gravity waves generated by the large-amplitude vertical oscillations of a circular cylinder in uniformly stratified fluid. Quantitative measurements are performed using a modified synthetic schlieren technique for strongly stratified solutions of NaCl or NaI. Oscillatory turbulent patches that develop around the cylinder are found to be the primary source of the observed quasi-monochromatic wave beams whose characteristics differ from theoretical predictions and experimental investigations of waves generated by small-amplitude cylinder oscillations. Over long times the waves break down into turbulence that is examined quantitatively through conductivity probe measurements and qualitatively through unprocessed synthetic schlieren images. Based on observations of the location of wave breakdown we determine that the likely mechanism for breakdown is through parametric subharmonic instability. This conclusion is supported by fully nonlinear numerical simulations of the evolution of a temporally monochromatic internal wave beam.

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering

Educators frequently neglect efforts to evaluate the affective components of instructional programs even though most agree that the affective domain is as important, or even more important, than the cognitive domain in learning. Measurement of cognitive attainment is easily accomplished, however, measurement of students' feelings, attitudes, concerns and values is difficult to accomplish.The purpose of the present research was to measure galvanic skin response (GSR) reactions of students to multi-media programs which were created to effect attitude change toward biological concepts in nonscience majors, and to thereby identify learning strategies or combinations of strategies that produce emotional and physiological reactions.The electronic response (ER) system of the Department of Biology at Ball State University was utilized in conducting the study. The effectiveness of producing emotional arousal by the strategies involved in nine ER programs was sampled by using the galvanic skin response (GSR) to measure the change in electrical skin conductance. The population tested for each ER program consisted of 30 subjects. An approximately equal number of males and females and an approximately equal number of morning, mid-day and afternoon sessions were sampled.In the treatment of data, the maximum GSR resistance, following specific ER program events, was calculated using a latency of approximately three seconds. Resistance per unit area of electrode plate surface was calculated in ohms/mm2 and converted to conductance (mhos/mm2). To establish a basis for comparing the emotional and attitudinal impact of each electronic response program, the maximum conductance for each event and information components of each event sequence was averaged for the 30 subjects.A dependent t-test for paired observations was utilized to determine the significant conductance change of corresponding components of the initial and final event sequences in each ER program. In those situations which were significant at the .05 probability level, farther comparisons were made between corresponding components of the initial and middle and middle and final event sequences. The t-test was also utilized to determine the significance of mean changes in conductance between selected information and question and question and answer slides within event sequences which produced a greater or lower conductance than previous event sequences, and those in which little variance or observable differences among components occurred.The principal conclusion drawn from the study is that the electronic response programs provide an effective mechanism for increasing emotional arousal, increasing involvement, and creating attitude change. All of the nine electronic response programs produced a gradual rise in average conductance from the beginning to the end of each program.Extremes in GSR reactions occurred in response to different types and combinations of narrative, pictorial presentations and musicalselections. Situations which created a mood or conveyed a feeling, possessed emotionally toned narrative or slides, or required a value stance or judgment produced the greatest GSR reactions. Calming, quiet, and relaxing music, unmoving slides, unemotional narration, questions lacking challenge or treating non-controversial subject matter, produced the smallest GSR reactions.The present study supports the contention that multiple stimuli, which increase the number of senses incorporated in the learning process and the interaction (response-reinforcement) of the learner, produce a greater emotional reaction than stimuli in one sense modality.The author considers that emotional responses involved and related with affective learning are as important, or more important, than cognitive attainment. Further investigations of the relationship between multimedia components and emotional arousal need to be carried out to ascertain the appropriate blending or combinations of stimuli which provide the best or most effective learning situations. Data obtained through research in the cognitive and affective aspects of instructional designs should also be correlated to determine how the most effective learning strategies can be developed.

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There is no abstract available for this thesis.

There is no abstract available for this thesis.

Two aspects of the problems encountered in searching for nucleon decay in the Soudan 2 detector are discussed. The types of event which are expected are discussed. The most common are Induced by gamma rays from the naturally occurring radioactive isotopes in the cavern rock. A calculation has been developed to predict the rates of such events in the detector and the results agree well when compared with measurements made underground. Some radioactive events cause Compton scattering in the wireplane region of the detector and prohibit the use of a simple multiplicity trigger. Such events have been studied. An electronic trigger system has been designed which will achieve a factor of 10³ rejection of these events while remaining efficient for even the most difficult modes of proton decay (75% for p -> K ⁺V ). It is predicted that radioactive triggers will occur at less than 3Hz when the full detector is operating. The neutrino induced background to proton decay has been simulated. The neutrino flux at the detector caused by cosmic ray induced showers in the atmosphere has been predicted. A comprehensive low energy (0.2 GeV to 20 GeV) Monte-Carlo neutrino event generator has been developed as a tool for background studies to proton decay. The Teinteraction of proton decay or neutrino interaction products in the parent nucleus is discussed. It is found that these reinteractions are quite probable, except for K⁺ and K° particles. Data from a low energy neutrino beam experiment has been studied and it is deduced that in some cases, the events seen in the detector will contain visible tracks associated with the disintegration of the parent nucleus. A background estimate for the mode p ➝ K⁺V from the neutrino interaction Vn ➝ μ~p is presented.