Compact patch antenna mountable above conducting plate for wlan operation

A compact patch antenna suitable for mounting above a conducting plate for WLAN operation in the 2.4 GHz band is presented. It is demonstrated that, by introducing a supporting metal plate connected to the antenna ground below, the proposed antenna in free space can easily be mounted at the corner of a conducting plate of various dimensions without rapidly deteriorating the antenna bandwidth. With a compact size of 20times20times6 mm, the antenna can be placed very close to a conducting plate of side length varied from 20 to 200 mm for application in a PC peripheral device     

Hermetic Packaging Using Eutectic SnPb Solder and Cr/Ni/Cu Metallurgy Layer

We have developed an easy, low-cost, and low-temperature optoelectronic hermetic packaging technology utilizing the eutectic SnPb solder and the Cr/Ni/Cu bonding pad. Bonding characteristics of the design were investigated in three different setups: silicon-silicon, silicon-glass, and glass-glass samples. Hermeticity was achieved at 200 degC without flux for all samples during the final bonding process. The bonding pads did not dewet during or after the reflow process. By utilizing the eutectic SnPb solder, the self-alignment process can be achieved. Because the bonding process was conducted through visual alignment, original misalignment was estimated to be more than 100 mum. The surface tension of melting solder during the reflow process allowed the samples to self-align and obtain a misalignment of less than 20 mum after solidification, which was 4% of the entire solder width. The bonding strength of the three setups ranged from 3 to 10 MPa. Among the three setups, glass-glass samples appear to have the strongest bonding strength. This low-temperature and cost-effective soldering process has demonstrated its feasibility and potential utilization in optoelectronic packaging     

Performance comparisons between PCA-EA-LBG and PCA-LBG-EA approaches in VQ codebook generation for image compression

The aim of this study is to generate vector quantisation (VQ) codebooks by integrating principle component analysis (PCA) algorithm, Linde-Buzo-Gray (LBG) algorithm, and evolutionary algorithms (EAs). The EAs include genetic algorithm (GA), particle swarm optimisation (PSO), honey bee mating optimisation (HBMO), and firefly algorithm (FF). The study is to provide performance comparisons between PCA-EA-LBG and PCA-LBG-EA approaches. The PCA-EA-LBG approaches contain PCA-GA-LBG, PCA-PSO-LBG, PCA-HBMO-LBG, and PCA-FF-LBG, while the PCA-LBG-EA approaches contain PCA-LBG, PCA-LBG-GA, PCA-LBG-PSO, PCA-LBG-HBMO, and PCA-LBG-FF. All training vectors of test images are grouped according to PCA. The PCA-EA-LBG used the vectors grouped by PCA as initial individuals, and the best solution gained by the EAs was given for LBG to discover a codebook. The PCA-LBG approach is to use the PCA to select vectors as initial individuals for LBG to find a codebook. The PCA-LBG-EA used the final result of PCA-LBG as an initial individual for EAs to find a codebook. The search schemes in PCA-EA-LBG first used global search and then applied local search skill, while in PCA-LBG-EA first used local search and then employed global search skill. The results verify that the PCA-EA-LBG indeed gain superior results compared to the PCA-LBG-EA, because the PCA-EA-LBG explores a global area to find a solution, and then exploits a better one from the local area of the solution. Furthermore the proposed PCA-EA-LBG approaches in designing VQ codebooks outperform existing approaches shown in the literature.     

Carbazole and benzimidazole/oxadiazole hybrids as bipolar host materials for sky blue,green, and red PhOLEDs

Two novel bipolar host materials (CBzIm and COxaPh) comprising of a hole-transport (HT) carbazole core functionalized with electron-transport (ET) moieties (benzimidazole/oxadiazole) at C3 and C6 positions have been synthesized. Their thermal, photophysical, electrochemical properties, and carrier mobilities were characterized. Theoretical calculations revealed that the HOMO orbitals were generally delocalized over the hole- and electron-transport moieties for both CBzIm and COxaPh, whereas the LUMO orbitals distribution only involved one benzimidazole moiety in CBzIm instead of fully delocalization over the whole polar moieties for COxaPh, which is consistent with the observation of good hole mobilities for both hosts and better electron mobility for COxaPh over CBzIm. CBzIm with high E_T (2.76 eV) is suitable to serve as a blue phosphor host, where a sky blue phosphor (DFPPM)₂Irpic exhibiting superior properties than those of popular blue emitter FIrpic was used to give highly efficient phosphorescent OLEDs, achieving a maximum external quantum efficiency (η_ext) of 15.7%. The better π-delocalization of COxaPh led to a lower triplet energy (E_T = 2.65 eV), which can be used to accommodate green and red phosphors, providing excellent device performance with η_ext as high as 17.7% for green [(ppy)₂Ir(acac)] and 20.6% for red [Os(bpftz)₂(PPh₂Me)₂], respectively.     

Synchronous multicast and broadcast service in multi-rate IEEE 802.16j WiMAX relay network

IEEE 802.16j Mobile Multihop Relay Standard defines multi-hop relay operation in a WiMAX system. It uses a novel synchronous multicast and broadcast transmission mechanism to achieve macro diversity. With the newly introduced synchronous delivery constraint, the multicast data delivery algorithm should be designed differently to enhance system performance. This paper provides Multi-Rate Selection Algorithm (MRSA) for multicast and broadcast (MBS) data delivery. It could reduce the data distribution delay from the BS to all the RSs. Besides, we also propose the path selection algorithm to further improve the effectiveness of MRSA. Our simulation results show that using MRSA with our shortest-path path selection algorithm, the delay for data delivery in 802.16j MBS system could be greatly reduced. The proposed scheme could achieve the performance closed to the optimal solutions. To the authors’ best knowledge, this is the first research work to investigate the IEEE 802.16j multicast and broadcast problem.     

Dual-output switched-capacitor DC–DC converter with pseudo-three-phase swap-and-cross control and amplitude modulation mechanism

This paper presents an inductorless dual-output switched-capacitor DC–DC converter employing pseudo-three-phase swap-and-cross control (PTPSCC) and an amplitude modulation mechanism (AMM). The AMM circuit scales the amplitudes of the driving signals for the switches according to the loading conditions in order to minimize switching losses. To reduce output ripples, average charge distribution, and improve regulation, the PTPSCC circuit continuously switches power transistors to deliver enough charge to the outputs by keeping at least one flying capacitor connected to each output. The switched capacitor DC–DC converter was implemented in a standard 0.18-μm 3.3-V CMOS process. Measurements were used to verify that the proposed converter provides dual independently regulated output voltages without cross regulation. The two outputs were regulated at 2.5 and 0.8 V with input ranges of 1.7–2 V. The maximum output loading was 100 mA for both outputs. A power efficiency of 90.5% was achieved at a maximum total output power of 330 mW with a switching frequency of 500 kHz, and a maximum power efficiency of 92.1% was achieved for a total output power of 210 mW. The maximal peak-to-peak output ripple voltages for the two outputs at 100 mA load currents were suppressed to below 26 and 20 mV, respectively.     

The Adaptive Ontology-Based Personalized Recommender System

Recommender systems provide strategies that help users search or make decisions within the overwhelming information spaces nowadays. They have played an important role in various areas such as e-commerce and e-learning. In this paper, we propose a hybrid recommendation strategy of content-based and knowledge-based methods that are flexible for any field to apply. By analyzing the past rating records of every user, the system learns the user’s preferences. After acquiring users’ preferences, the semantic search-and-discovery procedure takes place starting from a highly rated item. For every found item, the system evaluates the Interest Intensity indicating to what degree the user might like it. Recommender systems train a personalized estimating module using a genetic algorithm for each user, and the personalized estimating model helps improve the precision of the estimated scores. With the recommendation strategies and personalization strategies, users may have better recommendations that are closer to their preferences. In the latter part of this paper, a real-world case, a movie-recommender system adopting proposed recommendation strategies, is implemented.     

Electrophosphorescent Polyfluorenes Containing Osmium Complexes in the Conjugated Backbone

Electrophosphorescent copolymers have been synthesized by covalent bonding of a red‐emitting osmium complex Os(bpftz), which contains two 3‐trifluoromethyl‐5‐(4‐tert‐butyl‐2‐pyridyl)triazolate (bpftz) cyclometalated ligands, into the backbone of a bipolar polyfluorene (PF) copolymer. Employing these copolymers, a highly efficient red polymer light‐emitting diode has been realised that has an external quantum efficiency of 18.0%, a maximum brightness of 38 000 cd m^?2, and an emission centered at 618 nm. In addition, after incorporating appropriate amounts of green‐emitting benzothiadiazole (BT) and the aforementioned Os(bpftz) into the bipolar PF, an efficient white‐light electroluminescent polymer is obtained that displays simultaneous blue, green, and red emissions.     

HMM-based ball hitting event exploration system for broadcast baseball video

With the dramatic growth of fandom population, a considerable amount of research efforts have been devoted to baseball video processing. However, little work focuses on the detailed follow-ups of ball hitting events. This paper proposes a HMM-based ball hitting event exploration system for broadcast baseball video. Utilizing the strictly-defined layout of the baseball field, the proposed system first detects the game-specific spatial patterns in the field, such as the field lines, the bases, the pitch mound, etc. Then, the play region—the currently camera-focused region of the baseball field is identified for frame type classification. Since the temporal patterns of presenting the game progress follow a prototypical order, we consider the classified frame types as observation symbols and recognize ball hitting events using HMM. Experiments conducted on broadcast baseball video show encouraging results in frame type classification and ball hitting event recognition. Three practical applications, including highlight clip extraction by user-designated query, storyboard construction, and similar event retrieval, are introduced to address the applicability of our system.