Computation Controllable Mode Decision and Motion Estimation for Scalable Video Coding

This paper proposes an efficient computation‐aware mode decision and search point (SP) allocation algorithm for spatial and quality scalabilities in Scalable Video Coding. In our proposal, a linear model is derived to allocate the computation for macroblocks in enhancement layers by using the rate distortion costs of the base layer. In addition, an adaptive SP decision algorithm is proposed to decide the number of SPs for motion estimation under the constraint of the allocated computation. Experiment results demonstrate that the proposed algorithm allocates the computation resource efficiently and outperforms other works in rate distortion performance under the same computational availability constraint.     

Partial adaptive nulling on a monopulse phased array antenna system

A partial phase-only nulling (PPON) algorithm has been developed and evaluated on a 496-element monopulse phased array antenna system which employs five-bit phase shifters. Using this PPON algorithm allows nulls in the far-field pattern to be steered to the desired directions for a phased array equipped with low-resolution phase shifters to perform simultaneous nulling in the sum and two difference patterns in the environment of multiple jammers. Simulated and experimental patterns are illustrated     

Swarm intelligence‐based anycast routing protocol in ubiquitous networks

As digital devices with communication capability become more pervasive, we are entering the era of ubiquitous computing, as predicted by Mark Weiser. In ubiquitous environments, distributed context management servers are deployed everywhere to provide information and computing resources for users anytime and anywhere. Smart handheld computing devices with context‐aware applications may retrieve context information from the nearest server. This study investigates the problem of routing packets to the nearest server in a ubiquitous environment. An anycast routing protocol based on swarm intelligence, referred to as ARPSI, is proposed to route packets dynamically to a nearby server in a mobile, ad hoc, wireless network. Based on swarm intelligence, ARPSI is able to find a short path to a neighboring server efficiently and quickly. Simulations are conducted to evaluate the performance of ARPSI and our simulation results show that ARPSI achieves a higher packet delivery ratio, shorter routing path to anycast servers, and lower control packet overhead than the AODV‐based anycast protocol (A‐AODV) protocol. Copyright © 2009 John Wiley & Sons, Ltd.     

Utilization of self-injection Fabry–Perot laser diode for long-reach WDM-PON

In this investigation we propose and demonstrate a wavelength widely tunable laser source employing a self-injected Fabry–Perot laser diode (FP-LD) for long-reach wavelength-division-multiplexed passive optical network (WDM-PON). By using a tunable bandpass filter and an optical circulator inside the gain cavity, a stable and single-longitudinal-mode (SLM) laser output is achieved. Besides, the proposed laser sources are directly modulated at 2.5 Gb/s for both downlink and uplink transmissions of 85 km single mode fiber (SMF) in PON without dispersion compensation.     

Region-based image retrieval using color-size features of watershed regions

This paper presents a region-based image retrieval system that provides a user interface for helping to specify the watershed regions of interest within a query image. We first propose a new type of visual features, called color-size feature, which includes color-size histogram and moments, to integrate color and region-size information of watershed regions. Next, we design a scheme of region filtering that is based on color-size histogram to fast screen out some of most irrelevant regions and images for the preprocessing of the image retrieval. Our region-based image retrieval system applies the Earth Mover’s Distance in the design of the similarity measure for image ranking and matching. Finally, we present some experiments for the color-size feature, region filtering, and retrieval results that demonstrate the efficiency of our proposed system.     

Energy Quantization in Solution‐Processed Layers of Indium Oxide and Their Application in Resonant Tunneling Diodes

The formation of quantized energy states in ultrathin layers of indium oxide (In₂O₃) grown via spin coating and thermally annealed at 200 °C in air is studied. Optical absorption measurements reveal a characteristic widening of the optical band gap with reducing In₂O₃ layer thickness from ≈43 to ≈3 nm in agreement with theoretical predictions for an infinite quantum well. Through sequential deposition of In₂O₃ and gallium oxide (Ga­₂O₃) layers, superlattice‐like structures with controlled dimensionality and spatially varying conduction band characteristics are demonstrated. This simple method is then explored for the fabrication of functional double‐barrier resonant tunneling diodes. Nanoscale current mapping analysis using conductive atomic force microscopy reveals that resonant tunneling is not uniform but localized in specific regions of the apparent device area. The latter observation is attributed to variation in the layer(s) thickness of the In₂O₃ quantum well and/or the Ga₂O₃ barrier layers. Despite the nonidealities, the tremendous potential of solution‐processable oxide semiconductors for the development of quantum effect devices that have so far been demonstrated only via sophisticated growth techniques is demonstrated.     

Fullerene Additives Convert Ambipolar Transport to p‐Type Transport while Improving the Operational Stability of Organic Thin Film Transistors

Many high charge carrier mobility (μ) active layers within organic field‐effect transistor (OFET) configurations exhibit non‐linear current–voltage characteristics that may drift with time under applied bias and, when applying conventional equations for ideal FETs, may give inconsistent μ values. This study demonstrates that the introduction of electron deficient fullerene acceptors into thin films comprised of the high‐mobility semiconducting polymer PCDTPT suppresses an undesirable “double‐slope” in the current–voltage characteristics, improves operational stability, and changes ambipolar transport to unipolar transport. Examination of other high μ polymers shows general applicability. This study also shows that one can further reduce instability by tuning the relative electron affinity of the polymer and fullerene by creating blends containing different fullerene derivatives and semiconductor polymers. One can obtain hole μ values up to 5.6 cm² V^–1 s^–1 that are remarkably stable over multiple bias‐sweeping cycles. The results provide a simple, solution‐processable route to dictate transport properties and improve semiconductor durability in systems that display similar non‐idealities.     

Taxation on vehicle fuels: its impacts on switching to cleaner fuels

Vehicular consumption of fossil fuel contributes over 90% of air pollution in Hong Kong. A key strategy to improve Hong Kong's air quality is to discourage dirty fuels (e.g., leaded petrol and high-sulphur diesel) and to promote the use of clean fuels (e.g., low-sulphur diesel and liquefied petroleum gas (LPG)). This paper presents the empirical evidence on the effectiveness of the Government's clean fuel programs that offer tax subsidy to lower the consumption cost of such fuels. For the cases of unleaded petrol and ultra-low-sulphur diesel, lower fuel duties were offered so that the prices of these fuels were below those of leaded petrol and conventional diesel. Conventional petrol and diesel were phased out. In order to decide on the level of fuel duty concessions required to introduce LPG for taxis and bio-diesel for other vehicles, various Government-run trial programs were introduced to obtain cost estimates of using these alternative cleaner fuels. LPG using vehicles were subsequently exempted from the fuel duty in order to attract taxi and light bus operators to switch to LPG. It is apparent that the higher the subsidy, the faster is the rate at which switching to cleaner fuels takes place.