1,672 research outputs found
Biomaterials for Tendon/Ligament and Skin Regeneration
Tendon/ligament injury or skin injuries due to diseases, trauma, and surgery are common. Timely functional repair and tissue regeneration is a key to improve the quality of life of the patient while reducing health care cost. Tendon/ligament/skin is also enriched in a common extracellular matrix (ECM), collagen I, III, and elastin. Tissue engineering and regenerative medicine, the combination of (stem) cells, growth factors, and biomaterial scaffolds, is an emergent field, which has attracted substantial attention over the years. Biomaterials are considered the foundation of regenerative medicine. A key to find a new solution to tendon/ligament/skin healing is to synthesize new functional biomaterials, which have better biomechanical properties, biodegradability, and cell supporting properties. This chapter will review existing FDAāapproved biomaterialābased therapy, as well as those in development
Measurements of the ĻāĪ·distribution of Z ā Āµ+Āµ- events inppĀÆ collisions at ās = 1.96 TeVand measurements of the isolateddiphoton cross section in ppcollisions at ās = 8 TeV
Modeling and inversion of seismic data using multiple scattering, renormalization and homotopy methods
Seismic scattering theory plays an important role in seismic forward modeling and is the theoretical foundation for various seismic imaging methods. Full waveform inversion is a powerful technique for obtaining a high-resolution model of the subsurface. One objective of this thesis is to develop convergent scattering series solutions of the Lippmann-Schwinger equation in strongly scattering media using renormalization and homotopy methods. Other objectives of this thesis are to develop efficient full waveform inversion methods of time-lapse seismic data and, to investigate uncertainty quantification in full waveform inversion for anisotropic elastic media based on integral equation approaches and the iterated extended Kalman filter. The conventional Born scattering series is obtained by expanding the Lippmann-Schwinger equation in terms of an iterative solution based on perturbation theory. Such an expansion assumes weak scattering and may have the problems of convergence in strongly scattering media. This thesis presents two scattering series, referred to as convergent Born series (CBS) and homotopy analysis method (HAM) scattering series for frequency-domain seismic wave modeling. For the convergent Born series, a physical interpretation from the renormalization prospective is given. The homotopy scattering series is derived by using homotopy analysis method, which is based on a convergence control parameter and a convergence control operator that one can use to ensure convergence for strongly scattering media. The homotopy scattering scattering series solutions of the Lippmann-Schwinger equation, which is convergent in strongly scattering media. The homotopy scattering series is a kind of unified scattering series theory that includes the conventional and convergent Born series as special cases. The Fast Fourier Transform (FFT) is employed for efficient implementation of matrix-vector multiplication for the convergent Born series and the homotopy scattering series. This thesis presents homotopy methods for ray based seismic modeling in strongly anisotropic media. To overcome several limitations of small perturbations and weak anisotropy in obtaining the traveltime approximations in anisotropic media by expanding the anisotropic eikonal equation in terms of the anisotropic parameters and the elliptically anisotropic eikonal equation based on perturbation theory, this study applies the homotopy analysis method to the eikonal equation. Then this thesis presents a retrieved zero-order deformation equation that creates a map from the anisotropic eikonal equation to a linearized partial differential equation system. The new traveltime approximations are derived by using the linear and nonlinear operators in the retrieved zero-order deformation equation. Flexibility on variable anisotropy parameters is naturally incorporated into the linear differential equations, allowing a medium of arbitrarily anisotropy. This thesis investigates efficient target-oriented inversion strategies for improving full waveform inversion of time-lapse seismic data based on extending the distorted Born iterative T-matrix inverse scattering to a local inversion of a small region of interest (e. g. reservoir under production). The target-oriented approach is more efficient for inverting the monitor data. The target-oriented inversion strategy requires properly specifying the wavefield extrapolation operators in the integral equation formulation. By employing the T-matrix and the Gaussian beam based Greenās function, the wavefield extrapolation for the time-lapse inversion is performed in the baseline model from the survey surface to the target region. I demonstrate the method by presenting numerical examples illustrating the sequential and double difference strategies. To quantify the uncertainty and multiparameter trade-off in the full waveform inversion for anisotropic elastic media, this study applies the iterated extended Kalman filter to anisotropic elastic full waveform inversion based on the integral equation method. The sensitivity matrix is an explicit representation with Greenās functions based on the nonlinear inverse scattering theory. Taking the similarity of sequential strategy between the multi-scale frequency domain full waveform inversion and data assimilation with an iterated extended Kalman filter, this study applies the explicit representation of sensitivity matrix to the the framework of Bayesian inference and then estimate the uncertainties in the full waveform inversion. This thesis gives results of numerical tests with examples for anisotropic elastic media. They show that the proposed Bayesian inversion method can provide reasonable reconstruction results for the elastic coefficients of the stiffness tensor and the framework is suitable for accessing the uncertainties and analysis of parameter trade-offs
MEMS Gyroscope Research Based on UB Seed Grant
In this poster, the research on a novel MEMS gyroscope device based on UB faculty seed grant support is introduced. MEMS (Micro-electro-mechanical Systems) vibratory gyroscopes have attracted tremendous interest among researchers due to their small size, low energy consumption, low cost and long life-time. In my research, I conceived a novel bulk-micromachined electrostatic comb-driven, differential capacitance sensing MEMS vibratory gyroscope based on glass-silicon-glass sandwich-structure. The novel structure eliminates the parasitic capacitances of the gyroscope, which greatly eases the signal sensing. Furthermore, due to the device structure design, the sensing vibration is not coupled to the driving vibration, which improves the device stability. The MEMS gyroscope research is funded by UB seed grant. Based on the research, we published 1 journal paper and 1 conference paper. The research also resulted in the submission of 4 grant proposals, leading to a total funding of $60,016.77
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