Optimal block boundary pre/postfiltering for wavelet-based image and video compression.

This paper presents a pre/postfiltering framework to reduce the reconstruction errors near block boundaries in wavelet-based image and video compression. Two algorithms are developed to obtain the optimal filter, based on boundary filter bank and polyphase structure, respectively. A low-complexity structure is employed to approximate the optimal solution. Performances of the proposed method in the removal of JPEG 2000 tiling artifact and the jittering artifact of three-dimensional wavelet video coding are reported. Comparisons with other methods demonstrate the advantages of our pre/postfiltering framework.     

A low-power readout circuit for nanowire based hydrogen sensor

This paper presents a fully integrated lock-in amplifier intended for nanowire gas sensing. The nanowire will change its conductivity according to the concentration of an absorbing gas. To ensure an accurate nanowire impedance measurement, a lock-in technique is implemented to attenuate the low frequency noise and offset by synchronous demodulation or phase-sensitive detection (PSD). The dual-channel lock-in amplifier also provides both resistive and capacitive information of the nanowire in separate channels. Measurement results of test resistors and capacitors show a 2% resolution in the resistance range 10-40 kΩ and a 3% resolution in the capacitance range 0.5-1.8 nF. Moreover, a 28.7-32.1 kΩ impedance variation was measured through the lock-in amplifier for a single palladium nanowire that was exposed to a decreasing hydrogen concentration (10% H₂ in N₂ to air). The chip has been implemented with UMC 0.18 μm CMOS technology and occupies an area of 2 mm². The power consumption of the readout circuit is 2 mW from a 1.8 V supply.     

Optical add-drop multiplexers with low crosstalk

We propose and demonstrate three new optical add-drop multiplexer (OADM) architectures with simple and compact configuration and excellent crosstalk performance. The OADMs use a single multiport optical circulator and either one or two narrow-band fiber Bragg gratings, depending on the crosstalk requirement     

Lattice structure for regular paraunitary linear-phase filterbanksand M-band orthogonal symmetric wavelets

Parauninary linear-phase (PULP) M-channel uniform filterbanks, which are also known as the generalized lapped orthogonal transforms (GenLOTs), can be designed and implemented using lattice structures. This paper discusses how to impose regularity constraints onto the lattice structure of PULP filterbanks. These conditions are expressed in term of the rotation angles of the lattice components by which the resulting filterbanks are guaranteed to have one or two degrees of regularity, iterating these new regular filterbanks on the lowpass subband generates a large family of symmetric M-band orthonormal wavelets. Design procedures with many design examples are presented. Smooth interpolation using regular PULP filterbanks is illustrated through image coding experiments where the novel M-band wavelets consistently yield smoother reconstructed images and better perceptual quality     

A multidomain integrated‐radial‐basis‐function collocation method for elliptic problems

This article is concerned with the use of integrated radial‐basis‐function networks (IRBFNs) and nonoverlapping domain decompositions (DDs) for numerically solving one‐ and two‐dimensional elliptic problems. A substructuring technique is adopted, where subproblems are discretized by means of one‐dimensional IRBFNs. A distinguishing feature of the present DD technique is that the continuity of the RBF solution across the interfaces is enforced with one order higher than with conventional DD techniques. Several test problems governed by second‐ and fourth‐order differential equations are considered to investigate the accuracy of the proposed technique. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2008