Ferroelectric liquid crystals (FLCs) were known to possess fast response time under 1 ms. The low contrast ratio
yielding from defect alignment, however, limited their display application. Based on FLC elastic free energy, the
asymmetrical surface polarity controlled alignment was able to suppress the horizontal chevron defects in a half Vshaped
switching FLC cell. It is due to the FLC's spontaneous polarization (Ps) pointed to one direction inducing by the
opposite surface polarity in asymmetrical hybrid cell. The experimental approach of different alignment materials and
different strengths of surface anchoring energies were evaluated in this study. The highest contrast ratio of 780:1 at
saturation voltage under 5 V was obtained. The asymmetrical surface polarity controlled alignment technique provided
a promising FLC well alignment and fast switching result for TFT-LCD application.
A series of ferroelectric liquid crystals consisting new glassy liquid crystals (GLCs) as chiral dopants were prepared and
evaluated for their potentials in fast switching ability less than 1 ms. The properties of pure ferroelectric glassy liquid
crystals (FGLCs) and mixtures were reported in this paper. In particular, the novel FGLC possessing wide chiral
smectic C mesophase over 100 °C is able to suppress smectic A phase of host. The mixture containing 2.0 % GLC-1
performs greater alignment ability and higher contrast ratio than R2301 (Clariant, Japan) in a 2 μm pre-made cell (EHC,
Japan). These results indicate that novel FLC mixtures consisting glassy liquid crystals present a promising liquid
crystal materials for fast switching field sequential color displays.
Glassy liquid crystals (GLCs) possessing multi-functionalities, excellent morphological stability, and elevated phase transition temperature have been designed and synthesized for photonic device applications. Recent development has been reported on deterministic synthesis approach for scalable process in preparing GLC materials. The advanced processing eases the material preparation and tailors the material properties accordingly to suit device applications. These applications can be found in: (1) chiral nematic GLCs for circularly polarizers and notch filters, (2) photochromic nematic GLC, which can be photomodulated reflective indices in the solid states, for potential applications in nondestructive rewritable optical data storages and photonic switching, and (3) ferroelectric GLCs for potential fast switching light valves.
The outstanding coding performance of H.264 comes with the cost of significantly higher complexity, making it too complex to be applied widely. This work aims at accelerating the H.264 encoder using joint algorithm/code-level optimization techniques so as to make it feasible to perform real-time encoding on a commercial personal computer. We propose a fast inter-mode decision scheme based on spatio-temporal information of neighboring macroblocks for the algorithm-level optimization. We use a commercial profiling tool to identify most time consuming modules and then apply several code-level optimization techniques, including frame-memory rearrangement, single-instruction-multipledata (SIMD) implementations based on the Intel MMX/SSE2 instruction sets. Search mode reordering and early termination for variable block-size motion estimation, are then applied to speed up these time-critical modules. The simulation results show that our proposed joint optimization H.264 encoder achieves a speed-up factor of up to 18 compared to the reference encoder without introducing serious quality degradation.
We propose a fast coarse-to-fine video retrieval scheme using shot-level spatio-temporal statistics. The proposed scheme consists of a two-step coarse search and a fine search. At the coarse-search stage, the shot-level motion and color distributions are computed as the spatio-temporal features for shot matching. The first-pass coarse search uses the shot-level global statistics to cut down the size of the search space drastically. By adding an adjacent shot of the first query shot, the second-pass coarse-search introduces the "causality" relation between two consecutive shots to improve the search accuracy. As a result, the final fine-search step based on local color features of key-frames of the query shot is performed to further refine the search result. Experimental results show that the proposed methods can achieve good retrieval performance with a much reduced complexity compared to single-pass methods.
In this paper, various systolic arrays are proposed for the application to quadrature mirror filter (QMF) banks. A word-level systolic array is firstly presented to realize QMF banks. It is subsequently refined to bit-level array with bit-parallel arithmetic via the well-known two-level pipelining techniques and is then converted to bit-serial form by using the bit-serial inner product array proposed by Wang et al.. By applying the polyphase representation as well as fully utilizing the special relations among QMFs', aside from the memory cost, the whole filter bank can be constructed by using only about one half of the hardware expense of a prototype filter. In comparison with the direct realization using polyphase representation, the number of the systolic multiplier-accumulators (SMAs) required for our architecture is halved. Thus, both the chip area and transistor-count are reduced. As a result, with today's commercial CMOS technology, the whole filter bank can be implemented within a single-chip for various video applications.