This thesis investigates the computational principles underlying sensorimotor synchronization (SMS) through the novel application of deep reinforcement learning (RL). SMS, the coordination of rhythmic movement with external stimuli, is essential for human activities like music performance and social interaction, yet its neural mechanisms and learning processes are not fully understood. We present a computational framework utilizing recurrent neural networks with Long Short-Term Memory (LSTM) units, trained via RL, to model SMS behavior. This approach allows for the exploration of how different reward structures shape the acquisition and execution of synchronization skills. Our model is evaluated on both steady-state synchronization and perturbation response tasks, paralleling human SMS studies. Key findings reveal that agents trained with a combined reward—minimizing next-beat asynchrony and maintaining interval accuracy—exhibit human-like adaptive behaviors. Notably, these agents exhibited asymmetric error correction, making larger adjustments for late versus early taps, a phenomenon documented in human subjects. This suggests that such asymmetry may arise from the inherent reward structure of the task rather than from specific neural architectures. While our model did not consistently reproduce the negative mean asynchrony observed in human steady-state tapping, it demonstrated anticipatory behavior in response to perturbations. This offers new insights into how the brain might learn and execute rhythmic tasks, indicating that anticipatory strategies in human synchronization could naturally arise from processing rewards and timing errors. Our work contributes to the growing integration of machine learning techniques with cognitive neuroscience, offering new computational insights into the acquisition of timing skills. It establishes a flexible framework, which can be extended for future investigations in studying more complex rhythms, coordination between individuals, and even the neural basis of rhythm perception and production. / Thesis / Master of Science (MSc) / Have you ever wondered how we naturally tap our foot in time with music? This thesis investigates this human ability, known as sensorimotor synchronization, using artificial intelligence. By creating artificial agents that learn to tap along with a steady beat through reinforcement learning—like a person tapping to a metronome—we aimed to understand how the brain acquires this skill. Our experiments showed that how we define success, significantly affects how the agents learn the skill. Notably, when we rewarded both precise timing and consistent tapping, the agents' behavior closely resembled that of humans. They even exhibited a human-like pattern in error correction, making larger adjustments when tapping too late rather than too early. This research offers new insights into how our brains process and learn rhythm and timing. It also lays the groundwork for developing AI systems capable of replicating human-like timing behaviors, with potential applications in music technology and robotics.

Efficient exploitation and conservation of the oceans poses great technological challenges for scientists and engineers who must develop materials, structures and equipment for use in harsh environment of the oceans. For the applications of materials in marine environment, knowledge of the corrosion properties is essential for selection purposes. Presently, effort is being devoted to exploit deep-sea mineral resources. Deterioration of materials in the deep sea is due to the cumulative effect hydrostatic pressure, temperature, pH, dissolved oxygen, salinity and sea current. For the first time, in-situ corrosion measurements on the effect of deep sea environment on some metallic and composite materials were carried out at depths of 500,1200,3500, and 5100 m for 168,174 and 174 days of exposure in the Indian Ocean. Corrosion rate was obtained from weight loss measurements (mm/year) and surface morphology of as-exposed and cleaned specimens of the above materials was studied under scanning electron microscope and ED AX. Galvanic coupling of steel with zinc, magnesium and aluminium were also studied.. Tensile on metal and alloys and tensile, compressive, flexure and ILSS tests on carbon fibre reinforced composite specimen were performed on exposed specimens. XRD studies were conducted on the corrosion product of materials. In order to correlate the performance of materials in deep-sea environment, seawater current and temperature data were also collected at same period Results reveal that the corrosion behaviour of steels is controlled by dissolved oxygen prevailing and corrosion rate corresponds to dissolved oxygen available at these depth levels. This is due to the fact that oxygen acts as a cathodic deploarizer during corrosion reaction of steels in seawater. Corrosion rate of aluminium increases as the depth increases. This is due to the effect of hydrostatic pressure, which reduces the ionic radii of chlorine ions and facilitates easy penetration of these ions into surface layer. Titanium, titanium alloy (Ti-6A1-4V) and stainless steels did not show any deterioration at all depths studied. Morphology of as exposed and corroded coupons reveal different features. EDS analyses on exposed specimens are analyzed in light of seawater parameters. Carbon fibre reinforced composite did not show any change in properties like tensile, compression flexural and ILSS compared to control (unexposed) specimens. The deposition of calcium carbonate on galvanically coupled mild steel with zinc, aluminium and magnesium corresponds to availability of calcium in the deep ocean. EDS analyses on exposed coupons did not reveal calcium element below the calcium carbonate compensation depth (CCD) at 3800 m in Indian Ocean. Potentiodynamic polarization studies on some metals and alloys indicate that the behaviour of materials in deep-sea environment is a cumulative effect of all oceanographic parameters. Tensile test results on stainless steels SS-304 & SS-316L), titanium and titanium alloy (exposed) specimens did not show any significant change in their tensile properties and is again attributed to the passive film formed on its surface and nearly zero corrosion rate observed. Microbiological investigations on the exposed materials indicate that except carbon fibre reinforced composite all other metals and alloys harboured bacterial colonies. Results have been used to recommend structural materials suitable for the deep-sea applications.

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The diploma thesis present technology production of draining outlet. This is a rectangular deep drawn part, where basic shape is formed in two towing operations now. The used material is an austenitic stainless steel 17 240 with thickness 1 mm. According to the entry documentation the production technology was not change – current technology (it means drawing without thinning the wall) is most suitable. Based on technological and control calculations two-operations production was determined, which will take place in the united conventional instrument. The hydraulic press with marking Dieffenbacher PO250, which has a magnetic tool clamping, per stroke will perform here both operations. The payback was calculated for yearlong production 50 000 pieces after 0,8 years. The proposed production will make the current production more efficient including economic benefits.

The project looks for a solution to optimalization of rotational deep drawn part with flange production. It deals with sewerage drain, which is produced by conventional tool to two deep drawing operations. The used material is austenitic Cr-Ni stainless steel 1.4301. Suitability of this material for deep drawing operations was considered by means of the tensile test and the Erichsen test. On the bases of these results, serializability of production and theoretic relationships for determination of number of deep drawing operations, it was decided upon one operation serial production, by conventional tool without attenuation thickness of sheet. Production will take place on hydraulic press Dieffenbacher PO250 with magnetic tool fastening. The deep drawing tool was designed and constructed. For series of 2 000 units per year the rate of return was calculated after 4,7 years, while using the punch from the current second deep drawing operation it was calculated after 3,4 years.

No description available.

Deep tectonic tremor has been observed in major subduction zones, strike-slip faults, inland faulting systems, and arc-continent collision environments around the Pacific Rim. However, detailed space-time evolution of its source locations remains enigmatic because of difficulties in detecting and locating tremor accurately. In 2011, we installed two dense, small-aperture seismic arrays aiming to detect ambient tremor source beneath southern Central Range in Taiwan. We recorded continuous waveforms for a total of 134 days, including tremor triggered by the great 2011 Mw9.0 Tohoku earthquake. We use the broadband frequency-wavenumber beamforming and the moving-window grid-search methods to compute array parameters for detecting seismic signals. The obtained array parameters closely match both relocated local earthquakes and triggered tremor bursts located by an envelope cross-correlations method, indicating the robustness of our array technique. We identify tremor signals with coherent waveforms and deep incidence angles and detect tremor for 44 days among the 134-day study period. The total duration is 1,481-minute, which is 3-6 times more than that detected by the envelope cross-correlations method. In some cases, we observe rapid tremor migration with a speed at the order of 40-50 km/hour that is similar to the speed of fast tremor migration along-dip on narrow streaks in Japan and Cascadia. Our results suggest that dense array techniques are capable of capturing detailed spatiotemporal evolutions of tremor behaviors in southern Taiwan.

published_or_final_version / Physics / Master / Master of Philosophy

Road slips are common in Northland Allochthon residual clay soil, and are commonly mitigated using deep soil mixing (DSM). A deficiency in laboratory investigations on Northland Allochthon residual clay and a need for a better understanding of the numerical modelling of DSM columns used to mitigate unstable slopes in this soil type is evident in literature, and has been highlighted by practitioners. This research has aimed to fill aspects of these deficiencies. Field testing and classification tests have provided insight into how the soil varies between sites and with depth, and how in situ testing methods compare to one another. Field testing has also demonstrated that soil property changes around DSM columns have been shown to exist through seismic flat plate dilatometer testing before and after column installation, which has not previously been proven using an in situ method. This is important for practitioners who use DSM to demonstrate the additional soil improvements provided by the columns. The testing of reconstituted soil is fundamental in examining soil behaviour, and this study is the first to examine the triaxial behaviour of reconstituted specimens of Northland Allochthon soil. Laboratory triaxial testing and oedometer testing have allowed for a normalized comparison of the intact strength of Northland Allochthon residual clay soil to its reconstituted state. This work provides an answer to the important question regarding the role of soil structure in this soil type. It was revealed that soil structure results in increased shear strength of the soil, and that this increase is primarily cohesive in nature. The near coincidence of the post-rupture strength of intact specimens with the critical state angle of internal shearing resistance provides support for its use in examining first time slope failures in this soil type. This is an important finding for practitioners, as it demonstrates the value of testing reconstituted specimens, which are much easier to obtain than high quality intact specimens. In addition, relationships between the plasticity index (PI) of the soil and certain soil parameters (and soil behaviour) have been demonstrated to be relevant and useful for this soil type. Soil properties acquired in this study were tabulated along with those from other field sites in Northland Allochthon soil. It was found that there is significant variation between field sites, likely due to varying degrees of weathering, which is an important consideration for practitioners dealing with this soil type. A brief examination of constitutive models for representation of Northland Allochthon residual clay soil have shown that several different models can sufficiently represent the behaviour of this soil. The Mohr-Coulomb model was selected for use in subsequent finite element numerical models. A case study of a road slip at a field site in Northland Allochthon residual clay soil, mitigated using DSM columns, revealed that the use of a pre-existing slip surface after first time failure leads to an improved match between observed field behaviour and the behaviour of the slope as exhibited in a numerical model. This type of failure mechanism has not been previously examined in this soil type, and this case study demonstrates it is a useful approach that should be considered when dealing with second time failure in Northland Allochthon slopes. This numerical model also introduces the replacement ratio method (RRM), a technique used to represent the three dimensional (3D) geometry of the DSM columns in the more commonly used two dimensional (2D) analysis. Examination of laterally loaded DSM columns in plan view, which has not previously been performed in the context of DSM columns, has illustrated how installation effects and column shape influence load displacement curves, and demonstrates the effects of soil arching. This analysis provides practitioners with evidence that improved soil property changes, found to occur around DSM columns, lead to improved DSM column performance. A simplified 3D numerical model of laterally loaded DSM columns, which builds on the ideas developed in the previous two 2D models, has been compared to an identical 2D model. It is shown that the commonly used RRM results in an overestimation of the resisting force provided by the columns as compared to the 3D model. However, this does not necessarily imply that the use of the RRM in an analysis will always result in a safe slope. The degree to which its use will affect the results will depend on the slope geometry, location of the DSM columns, and the type of analysis performed (i.e. factor of safety or deformation based). A modification to the RRM has been proposed. It is recommended that when the DSM column diameter and soil properties are similar to those used in this study, the MRRM developed in this study should be utilized. In circumstances where they differ, it is recommended that practitioners perform a sensitivity analysis using the MRRM developed here as a basis for modifying the RRM in order to determine the extent to which their results are influenced. If the influence is significant, the use of a 3D model should be considered.

No description available.