Browsing by Author "Wang, Wei"
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Item A Collision Deformer for Autodesk Maya(2015-03-04) Wang, WeiBelievable physical interactions involving collisions between objects are essential in motion graphics and video games. The most common approach to create such effect is to employ dynamics simulation. However, to create a simple collision effect, dynamics simulation is time-consuming and lacks artistic control. This paper presents a custom deformer for creating simple collision effects in Autodesk Maya. The deformer determines intersection between objects by performing inclusion tests for selected vertices, and approximates the elastic behavior of the soft body in response to collisions by applying a controllable deforming algorithm to the object surface. No physics simulation is required in this process. The deformer supports interacting with multiple collider objects and at the same time provides artistic control for the user to manage the deformation. The deformer has proven successful for creating plausible deformation of simple collision interactions in a fast, controllable manner.Item A hydrograph-based prediction of meander migration(Texas A&M University, 2006-08-16) Wang, WeiMeander migration is a process in which water flow erodes soil on one bank and deposits it on the opposite bank creating a gradual shift of the bank line over time. For bridges crossing such a river, the soil foundation of the abutments may be eroded away before the designed lifetime is reached. For highways parallel to and close to such a river, the whole road may be eaten away. This problem is costing millions of dollars to TxDOT in protection of affected bridges and highway embankments. This research is aimed at developing a methodology which will predict the possible migration of a meander considering the design life of bridges crossing it and highways parallel to it. The approaches we use are experimental tests, numerical simulation, modeling of migration, risk analysis, and development of a computer program. Experimental tests can simulate river flow in a controlled environment. Influential parameters can be chosen, adjusted, and varied systematically to quantify their influence on the problem. The role of numerical simulation is to model the flow field and the stress field at the soil-water interface. Migration modeling is intended to integrate the results of experimental tests and numerical simulations and to develop a model which can make predictions. The Hyperbolic Model is used and its two major components Mmax equation and τmax equation are developed. Uncertainties in the parameters used for prediction make deterministic prediction less meaningful. Risk analysis is used to make the prediction based on a probabilistic approach. Hand calculation is too laborious to apply these procedures. Thus the development of a user friendly computer program is needed to automate the calculations. Experiments performed show that the Hyperbolic Model matches the test data well and is suitable for the prediction of meander migration. Based on analysis of shear stress data from numerical simulation, the τmax equation was derived for the Hyperbolic Model. Extensive work on the simplification of river geometry produced a working solution. The geometry of river channels can be automatically simplified into arcs and straight lines. Future hydrograph is critical to risk analysis. Tens of thousands of hydrographs bearing the same statistical characteristics as in history can be generated. The final product that can be directly used, the MEANDER program, consists of 11,600 lines of code in C++ and 2,500 lines of code in Matlab, not including the part of risk analysis. The computer program is ready for practice engineers to make predictions based on the findings of this research.Item Optimization of VAV AHU Terminal Box Minimum Airflow(2011-10-21) Wang, WeiDetermining the optimal terminal box airflow is a complex process which is influenced by various factors, such as weather condition, supply air temperature, primary air fraction and internal load. A guideline for determination of a cost efficient minimum airflow setpoint for VAV terminal box units is drawn in this research. The most efficient optimal minimum airflow setpoint should not be a fix setting, but should be changing with zone load and ventilation requirement. A fixed minimum airflow is used in conventional control strategies. The terminal box minimum airflow required is not a constant since the supply air temperature, fresh air fraction and zone load are different. It is important to set up the minimum airflow to ensure IAQ and thermal comfort and to minimize energy consumption. Analysis has been carried out to compare how the supply air temperature, fresh air fraction and zone load affect the minimum airflow setting of an exterior zone. And 30% of design airflow is not always a good number, and may cause comfort issue or ventilation problem. If the minimum airflow is set higher than required, terminal boxes will have significantly simultaneous heating and cooling, and consume more fan power in the AHUs. If the minimum airflow is set lower than required, indoor air quality (IAQ) will be a concern. Energy saving ratio study is conducted to estimate the energy saving benefit by implementing an optimized minimum airflow.Item Plasmonic properties of subwavelength structures and plasmonic optical devices(2009-08) Wang, Wei; Chen, ShaochenThis thesis proposes a metallic hole array of a rectangular converging-diverging channel (RCDC) shape with extraordinary transmission. We use a three-dimensional (3D) finite element method to analyze the transmission characteristics of two-dimensional metallic hole arrays (2D-MHA) with RCDC. For a straight channel MHA, when the aperture size is reduced, the transmission peaks have a blue-shift. The same result is observed for a smaller gap throat for the RCDC structure. For the rectangular holes with a high length-width ratio, a similar blue-shift in the transmission peaks as well as a narrower full width at half maximum (FWHM) are observed. The asymmetry from the rectangular shape gives this structure high selectivity for light with different polarizations. Furthermore, the RCDC shape gives extra degrees of geometrical variables to 2D-MHA for tuning the location of the transmission peak and FWHM. The tunable transmission property of this structure shows promise for applications in tunable filters, photonic circuits, and biosensors.