Chun-Yeon Lin

Improvement of the Microcrystalline Cube Corner Reflective Structure and Efficiency

Techniques such as micro machining and mirror finishing can be applied to polycarbonate (PC) optical plastic materials to create molds with microcrystalline cube corner structures. Micro hot-embossing can then be used to create retro-reflective experimental samples that make use of cube corner retro-reflection. This kind of reflector is a microcrystalline structure, so there are about 149,000 cube corners in each square inch of the surface. With a thickness as small as 0.2–0.3 mm, the reflector can be used for very thin areas. We also proposed an alternate design for microcrystalline structures to increase the retro-reflection efficiency at low angles of incidence. Samples were manufactured for testing to provide corroboration for the theory. At the same time, we analyzed the geometric and optical properties of a reflector composed of microcrystalline cube corner structures on PC optical plastic to determine its retro-reflection efficiency. This was also simulated and calculated using a self-written program. Therefore, microcrystalline cube corners can be used to modify a reflective structure to improve the efficiency of retro-reflection.

Magnetic Tensor Sensor and Way-Finding Method Based on Geomagnetic Field Effects With Applications for Visually Impaired Users

This paper presents a method utilizing geomagnetic field effects commonly found in nature to help the visually impaired persons (VIPs) navigate safely and efficiently; both indoor and outdoor applications are considered. Magnetic information indicating special locations can be incorporated as waypoints on a map to provide a basis to help the user follow a map that amalgamates the waypoints into spatial information. Along with a magnetic tensor sensor (MTS), a navigation system for helping VIPs more effectively comprehend their surroundings is presented. With the waypoint-enhanced map and an improved dynamic-time-warping algorithm, this system estimates the users locations from real-time measured magnetic data. Methods using image data to enhance waypoints at dangerous locations are discussed. The MTS-enhanced method can be integrated into existing personal mobile devices (with built-in sound, image, video, and vibration alert capabilities) to take advantages of the rapidly developing internet, global positioning systems, and computing technologies to overcome several shortcomings of blind-assistive devices. A prototype MTS-enhanced system for indoor/outdoor navigation has been developed and demonstrated experimentally. Although the MTS and algorithm are presented in the context of way-finding for a VIP, the findings presented here provide a basis for a wide range of applications where geomagnetic field effects offer an advantage.

A novel architecture for converting single 2D image into 3D effect image

A novel 2D to 3D effect image conversion architecture integrated image segmentation system and depth estimation is presented. Its objective is to describe the technique used to generate stereo pair images starting from a single image source (a view-point) and its related depth map. The conjunction between segmented image and depth map allows reconstructing artificially the binocular view producing a 3D effect depending on screen dimension and image resolution. The system consists of an online ICA mixture model that performs image segmentation and depth estimation method to obtain the depth information of image. The proposed system is capable of performing automatic multilevel segmentation of images, based on depth information obtained by the image depth estimation method. The system does not reconstruct the real 3D coordinates of any object inside the scene, but simply assigns the most comfortable shift to the source points to give a 3D-entertainment to the viewer. A simple smoothing filtering technique adaptively resolves the occlusions generated by shifting of the source points without introducing visible and/or annoying artifacts.

Design concept of a novel EM-array magnetic scanning system for continuous motion control of maximum MFD

This paper presents the design concept and operational principle of a magnetic scanning system for controlling the continuous motion of its maximum magnetic flux density (MFD) in a plane at high speed using an electromagnet (EM) array. Unlike a traditional EM-array where discrete points are controlled for stimulation, actuating or sensing, the synthetized MFD field of the EM array is accurately controlled between adjacent EMs for displaying high-resolution patterns with a relatively small number of EMs. The theory for generating the synthetized MFD that has the Gaussian function properties and three design criteria evaluating its performance as well as the algorithm for implementing it on the 2D EM-array are detailed; both 1D and 2D basic units for line and area scanning are considered. Results agree well with analytically derived exact solutions. Two illustrative application examples are given to demonstrate the applications of an EM array for magnetically reconstructing a cross-road sign pattern, and for generating a moving eddy current field.

An investigation on temperature measurements for machining of titanium alloy using ir imager with physics-based reconstruction

In general, the physical field in a domain can be uniquely determined from appropriate physical laws by its field conditions on its boundary surfaces. In machining, the ability to measure the tool surface temperature distribution is highly desirable as it provides an essential basis to reconstruct the thermal model for monitoring tool and workpiece conditions, particularly when machining hard to machine materials (such as titanium alloy that exhibits excellent mechanical properties and corrosion resistance). Because of the extremely high temperature gradient within a very small area, the need for developing an effective non-contact measurement technique has been a well-recognized problem. In the context of dry lathe-turning of titanium alloy, this paper presents a method based on non-contact infrared images to reconstruct the temperature field of the tool insert. Unlike traditional methods that base on limited thermocouple measurements or direct reading of absolute temperature from infrared images, the method presented here utilizes physical laws and heat transfer properties (temperature contours and their gradients) to identify thermal discontinuities, separate chips from the tool insert and reconstruct the obtruded tool temperature field.

LUMPED-PARAMETER MODELING FOR MENISCUS DYNAMIC ANALYSIS IN IMMERSION FLOW FIELD

Motivated by the interest to increase production throughputs of immersion lithography machines, wafers are scanned at increasingly high velocities and accelerations, which may result in liquid loss at the receding contact line. The dynamic characteristics of the immersion fluid with free boundary play an important role for fluid management system, and are concerned in various potential immersion unit designs. To offer intuitive insights into the dynamic effects of the immersion fluid due to scan speeds, a lumped-parameter model is developed to characterize the hydrodynamics of the immersion flow process. To validate the model, meniscus behavior information under dynamic conditions is extracted experimentally and analyzed using image processing techniques. The reduced model agrees qualitatively well with the experimental data revealing that parts of the surface tension have an effect on the dynamic response of the menisci similar to that due to a pure time delay in the system.Copyright

Harmonic response of an eddy-current sensor for real-time measurement of thin-wall titanium alloy workpiece

Motivated by the needs to develop a sensing method that simultaneously characterizes the dynamic behavior and system properties for analyzing and controlling a physical system, this paper formulates the harmonic response of an eddy-current (EC) sensor using the distributed current source (DCS) models to determine the workpiece thickness and displacement from the measured magnetic flux density of the induced EC. The DCS modeling methods, which base on physically intuitive closed-form solutions to derive the response to an input current through an electromagnet, do not require time-consuming and complicated meshes including the air-space as needed for a finite-element analysis. The effectiveness of the closed-form approximation for real-time applications has been verified against exact integral solutions and finite-element analysis (FEA), which requires less than 1% of the exact integral computation and yet is capable of achieving relatively high accuracy of about 2% maximum error. The models have been applied to derive a mapping between experimentally measured harmonic response of the induced EC field and the thickness/displacement of a titanium alloy workpiece.

Lumped-Parameter Modeling of an Immersion Flow Field for Analyzing Meniscus Dynamic Behavior

Motivated by the interest to increase production throughputs of immersion lithography machines, wafers are scanned at increasingly high velocities and accelerations, which may result in liquid loss at the receding contact line. The dynamic characteristics of the immersion fluid with free boundary play an important role for fluid management system, and are concerned in various potential immersion unit designs. To offer intuitive insights into the dynamic effects of the immersion fluid due to scan speeds, a lumped-parameter model based on two-dimensional (2D) image data has been developed to characterize the 3D hydrodynamics of the immersion flow process. To validate the model, meniscus behavior information under dynamic conditions is extracted experimentally and analyzed using image processing techniques. The reduced model agrees qualitatively well with the experimental data.

Coupled Parametric Effects on Magnetic Fields of Eddy-Current Induced in Non-Ferrous Metal Plate for Simultaneous Estimation of Geometrical Parameters and Electrical Conductivity

Illustrated with a magnetic field based eddy-current (EC) sensor which utilizes an anisotropic magneto-resistive sensor to directly measure the magnetic flux density (MFD) generated by the EC induced in a non-ferrous metal plate, this paper presents a material-independent method for multi-objective estimation of the plate geometrical parameters and/or electrical conductivity using frequency response analysis. The model, which agrees well with a 2-D axis-symmetric finite-element analysis, relates the measured (EC-generated) MFD to three dimensionless parameters (skin depth, plate thickness, and sensor-plate distance) normalized relative to a specified coil design. Data in the material-independent model that provides the basis to investigate the parametric effects on measured MFD can be regrouped in 2-D maps for simultaneously measuring any two of the three parameters. Experimental measurements were conducted on three different materials (Aluminum, Titanium, and Titanium alloy) with different thicknesses and sensor-plate distances between 1 and 5 mm operating in the frequency range from 100 Hz to 42.8 kHz. Experimental results show that the maximum difference between the analytically computed and experimental data is in the order of 5%, and demonstrate that the method has the capability of simultaneously measuring two unknowns out of three geometrical and/or material properties using a material-independent 2-D map.

A Continuous-Field Actuation Method for Transducing Optical Color Images to Magnetic/Eddy-Current Patterns

Motivated by two applications (retinal prosthesis and nondestructive damage detection), this research develops a new actuator utilizing magnetic/electric fields as media to enable open-loop induction control of a relatively high-resolution eddy-current pattern on an electrically conductive surface with a relatively small number of electromagnets (EMs). The actuator referred to here as a magnetic/eddy-current (M/EC) continuous field scanner transduces an image into an M/EC pattern induced by a two-dimensional EM array. Unlike traditional digital stimulation devices where the spatial resolution is defined by discrete spacing between two adjacent electrodes, the continuous-field scanner accurately controls the synthetized M/EC fields between adjacent EMs. Along with a detailed presentation of an analytical model and its inverse solutions to enable the continuous-field scanning, this paper presents a numerical study to investigate the effects of key design parameters, and some preliminary experimental results to validate the concept feasibility of the proposed method.Copyright