Tao Dai

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Electrical impedance tomography (EIT) calculates images of the body from body impedance measurements. While the spatial resolution of these images is relatively low, the temporal resolution of EIT data can be high. Most EIT reconstruction algorithms solve each data frame independently, although Kalman filter algorithms track the image changes across frames.(More)
—This paper proposes 4-D EIT image reconstruction for functional EIT measurements. The approach directly accounts for 3-D interslice spatial correlations and temporal correlations between images in successive data frames. Image reconstruction is posed in terms of an augmented image˜x and measurement vector˜y, which concatenate the values from the d previous(More)
This paper describes an in vivo measurement technique to calculate dielectric properties of blood excluding the contributions from surrounding tissues, based on analysis of the pulsatile component bioimpedance spectroscopy data. A tetrapolar electrode system applied on the fingers is simulated by a pspice equivalent circuit, and current is injected with(More)
Electrical Impedance Tomography (EIT) calculates the internal conductivity distribution within a body from current simulation and voltage measurements on the body surface. Two main technical difficulties of EIT are its low spatial resolution and sensitivity to measurement errors. Image reconstruction using l(1) norms allows addressing both difficulties, in(More)
Magnetic induction tomography (MIT) is a new technique to image the electromagnetic properties of an object by mutual induction data of pairs of excitation and sensing coils. MIT has potential in visualization of metal flow for continuous casting mainly because of its potential to deliver images with high temporal resolution. A dynamic magnetic induction(More)
Electrical impedance tomography (EIT) reconstructs a conductivity change image within a body from electrical measurements on the body surface; while it has relatively low spatial resolution, it has a high temporal resolution. One key difficulty with EIT measurements is due to the movement and position uncertainty of the electrodes, especially due to(More)
We present a grating model of two-dimensional (2D) rigorous coupled wave analysis (RCWA) to study top diffraction gratings on light-emitting diodes (LEDs). We compare the integrated-transmission of the non-grating, rectangular-grating, and triangular-grating cases for the same grating period of 6 µm, and show that the triangular grating has the best(More)
The Gallium Nitride (GaN) Light-Emitting-Diode (LED) bottom refection grating simulation and results are presented. A microstructure GaN bottom grating, either conical holes or cylindrical holes, was calculated and compared with the non-grating (flat) case. A time monitor was also placed just above the top of the LED to measure both time and power output(More)
Characterization of blood impedance properties is important to estimate clinical diagnostic indices such as haematocrit, glucose level and hydration. Current in vivo bioimpedance spectroscopy methods are performed on a body appendage and thus represent a combined measurement of all tissues in the measurement field, rather than the blood individually. This(More)
We present simulation results of the indium tin oxide (ITO) top diffraction grating using a rigorous couple wave analysis (RCWA) for GaN LEDs. We study three different nano-structure patterns: cylindrical pillar grating, conical pillar grating, and cylindrical nano-hole grating. We show the light transmission improvement with nano-grating designs and(More)