Yong, Yan

This research develops a new pipeline for large-scale point cloud registration by integrating chunked-based data processing within feature-based deep learning models to align aerial LiDAR and UAV photogrammetric data. By processing data in manageable chunks, this approach optimizes memory usage while retaining the spatial continuity essential for precise alignment across expansive datasets. Three models—DeepGMR, FMR, and PointNetLK—were evaluated within this framework, demonstrating the pipeline’s robustness in handling datasets with up to 49.73 million points. The models achieved average epoch times of 35 seconds for DeepGMR, 112 seconds for FMR, and 333 seconds for PointNetLK. Accuracy in alignment was also reliable, with rotation errors averaging 2.955, 1.966, and 1.918 degrees, and translation errors at 0.174, 0.191, and 0.175 meters, respectively. This scalable, high-performance pipeline offers a practical solution for spatial data processing, making it suitable for applications that require precise alignment in large, cross-source datasets, such as mapping, urban planning, and environmental analysis.

An analytical method is proposed for the response analysis of lifeline structures subjected to earthquake excitations. The main feature of the approach is to consider the vibrational motion as a result of the wave motion in a waveguide-like lifeline structure. Based on the theory of wave propagation, scattering matrices are derived to characterize the wave propagation in individual segments and wave reflections and transmissions at supports and boundaries. Response solution is derived in a closed form, suitable for stochastic analysis when the input is an earthquake excitation. A space-time earthquake ground motion model that accounts for both coherent decay and seismic wave propagation is used to specify motions at supports. The proposed technique can be used to obtain lifeline structural response accurately and determine the correlation between any two locations in an effective manner. The computational aspects of its implementation are also discussed. Numerical examples are presented to illustrate the application and efficiency of the proposed analytical scheme.

The dynamic response of plate structures composed of rigidly connected thin plates subjected to point loads is studied. The finite strip method combined with a new approach for analyzing periodic structures is utilized to obtain substantial reduction in computational efforts. Each strip with various boundary conditions is treated as a waveguide capable of transmitting different wave motions. Wave scattering matrices are defined to characterize wave motions at boundaries, intersection of plates and where type of wave guides are changed. The results obtained from the application of the approach on various plate configurations are presented and discussed.

A new analytical method based on the wave propagation scheme has been developed for the dynamic analysis of axially symmetric shells with arbitrary boundary conditions and interior supports. In this approach, a shell structure is considered as a waveguide and the response to external excitations is treated as a superposition of wave motions. To segregate the effect of the interior supports, the waveguide is first divided into several sub-waveguides. Upon analyzing these sub-waveguides separately, a composition scheme is adopted to relate them by connecting the wave components according to the continuity conditions for the state variables at each interior supports. Closed form solutions for free and random vibration are derived. The proposed method is presented in a general fashion and numerical examples are given to illustrate the application of the theory.

A folding span deployed between two ships is proposed for dry cargo transfer during replenishment operations at sea. This structure is modeled as a one-dimensional truss-work, composed of spatially periodic units. The governing equation is formulated for a single periodic unit by a finite element method. A transfer matrix method is then used to connect it to its neighboring units. The dynamic response of the structure is finally obtained by a wave propagation approach. For application to underway replenishment (UNREP), this analysis is extended to the case of a travelling load and to the case of moving boundaries, which accounts for the relative motion of the supplying and receiving ships. Moreover, a parametric study is conducted for future design purpose.

A new turbulence model is proposed in this dissertation for two-dimensional incompressible turbulent flows. The methodology used in the present study is a unilateral-statistical-average scheme with the concept of orthotropic eddy viscosity. This methodology has never been explored before in any research work of this nature. The distinguished feature of the unilateral-statistical-average scheme, compared to Reynolds averaging, is that the first-order information of the fluctuating velocity field is retained. This is achieved by dividing the fluctuating velocities into two groups and applying the average only to a single group. It is proved that the mean value of the fluctuating velocities of the first group solutions is not equal to zero. This non-zero quantity, together with a specified length vector, is used to define a 3 x 3 matrix of orthotropic eddy viscosity. In an off-streamline coordinate system, the eddy-viscosity matrix exhibits anisotropy characteristic, where each component of the turbulent stresses is related to all the components of the rate of strains of the mean fluid flow. The present model has been successfully applied to turbulent boundary-layer flow, turbulent free-shear jet flow, and turbulent wall-bounded separation flow without using empirical constants or wall-functions. Good agreements between the numerical results and experimental data or empirical predictions demonstrate that the unilateral-statistical-average scheme and the orthotropic non-linear eddy-viscosity formulation are robust and efficient in modeling basic turbulent flows. Applicability and predictability of the model to more complex engineering turbulence problems are worthy of further investigation in the future research.

The objective of the study is to determine the structural response to external force and earthquake excitations with consideration of soil-structure interaction. The physical model concerned herein is an N-story building on a rigid or flexible foundation embedded in a layered soil medium. In this substructure approach, the soil medium and the structure are treated as one-dimensional waveguides and their motions are characterized as wave scattering. To include effects of soil-structure interaction, the foundation response is expressed as a summation of influence functions, which are defined as the response to a simple stress distribution over the contact surface between the soil and foundation. The analysis, therefore, is carried out without solving integral equations. The coupling effect is recovered by using equilibrium, compatibility and reciprocal conditions. As a result, the structural response solution is expressed in terms of parameters of a seismic source and external excitations, and can be used in a statistical analysis if uncertainties of these parameters are taken into account.