Energy- and Latency-Efficient Processing of Full-Text Searches on a Wireless Broadcast Stream

In wireless mobile computing environments, broadcasting is an effective and scalable technique to disseminate information to a massive number of clients, wherein the energy usage and latency are considered major concerns. This paper presents an indexing scheme for the energy- and latency-efficient processing of full-text searches over the wireless broadcast data stream. Although a lot of access methods and index structures have been proposed in the past for full-text searches, all of them are targeted for data in disk storage, not wireless broadcast channels. For full-text searches on a wireless broadcast stream, we firstly introduce a naive, inverted list-style indexing method, where inverted lists are placed in front of the data on the wireless channel. In order to reduce the latency overhead, we propose a two-level indexing method which adds another level of index structure to the basic inverted list-style index. In addition, we propose a replication strategy of the index list and index tree to further improve the latency performance. We analyze the performance of the proposed indexing scheme with respect to the latency and energy usage measures, and show the optimality of index replication. The correctness of the analysis is demonstrated through simulation experiments, and the effectiveness of the proposed scheme is shown by implementing a real wireless information delivery system.     

Impact of a simple load balancing approach and an incentive-based scheme on MANET performance

Most reactive mobile ad hoc network (MANET) routing protocols such as AODV and DSR do not perform search for new routes until the network topology changes. But, low node mobility does not affect the MANET connectivity and the same routes may be used for a long time. This may cause concentration of traffic on few mobile stations (MSs), which results in congestion and hence longer end-to-end delay. In addition, continuous use of MSs may cause their battery power to get exhausted rapidly. Expiration of MS energy causes disruption of connections traversing through the MSs and could generate many simultaneous new routing requests. Therefore, we propose a load balancing approach called Simple Load Balancing Approach (SLBA), which can be transparently added to any current reactive routing protocol such as AODV and DSR. SLBA minimizes the traffic concentration by allowing each MS to drop RREQ or to give up packet forwarding depending on its own traffic load. Meanwhile, MSs may deliberately give up forwarding packets to save their own energy. For encouraging MSs to volunteer in forwarding packets, we introduce a reward scheme for packet forwarding, named Protocol-Independent Fairness Algorithm (PIFA). We compare the performance of AODV and DSR with and without SLBA and PIFA. Simulation results indicate that SLBA can distribute traffic very well and improve the MANET performance. PIFA is also observed to prevent MANET partitioning and any performance degradation due to selfish nodes.     

CORE: Common Region Extension Based Multiple Protein Structure Alignment for Producing Multiple Solution

Over the past several decades, biologists have conducted numerous studies examining both general and specific functions of proteins. Generally, if similarities in either the structure or sequence of amino acids exist for two proteins, then a common biological function is expected. Protein function is determined primarily based on the structure rather than the sequence of amino acids. The algorithm for protein structure alignment is an essential tool for the research. The quality of the algorithm depends on the quality of the similarity measure that is used, and the similarity measure is an objective function used to determine the best alignment. However, none of existing similarity measures became golden standard because of their individual strength and weakness. They require excessive filtering to find a single alignment. In this paper, we introduce a new strategy that finds not a single alignment, but multiple alignments with di?erent lengths. This method has obvious benefits of high quality alignment. However, this novel method leads to a new problem that the running time for this method is considerably longer than that for methods that find only a single alignment. To address this problem, we propose algorithms that can locate a common region (CORE) of multiple alignment candidates, and can then extend the CORE into multiple alignments. Because the CORE can be defined from a final alignment, we introduce CORE* that is similar to CORE and propose an algorithm to identify the CORE*. By adopting CORE* and dynamic programming, our proposed method produces multiple alignments of various lengths with higher accuracy than previous methods. In the experiments, the alignments identified by our algorithm are longer than those obtained by TM-align by 17% and 15.48%, on average, when the comparison is conducted at the level of super-family and fold, respectively.     

Modal parameter identification of a containment using ambient vibration measurements

Ensuring and maintaining the structural integrity of the containment structure in nuclear power plants is essential for preserving the nuclear reactor and other safety-related systems as well as protecting plant workers and publics from hazardous radioactive materials. To date, the structural integrity of the containment has been evaluated periodically via various nondestructive inspection methods. However, these methods require considerable time and cost to estimate overall structural integrity. In this paper, the possibility of monitoring the structural integrity of the containment utilizing ambient vibration measurement is explored. The ambient vibration testing was selected because it can avoid the interruption of normal operation of power plants. To fulfill the objective, the ambient vibration of the containment of Ulchin Nuclear Power Plant Unit 5 in Korea was measured, and the modal parameters, i.e., resonant frequencies and corresponding mode shapes, were extracted using the modal identification techniques in the frequency domain, i.e., the peak picking and the frequency domain decomposition methods. Using the extracted modal parameters and the finite element model, the elastic modulus of the concrete was estimated based on the sensitivity-based system identification method.     

Large Magnetovolume Effect Induced by Embedding Ferromagnetic Clusters into Antiferromagnetic Matrix of Cobaltite Perovskite

Materials that show negative thermal expansion (NTE) have significant industrial merit because they can be used to fabricate composites whose dimensions remain invariant upon heating. In some materials, NTE is concomitant with the spontaneous magnetization due to the magnetovolume effect (MVE). Here the authors report a new class of MVE material; namely, a layered perovskite PrBaCo₂O_5.5+x (0 ≤ x ≤ 0.41), in which strong NTE [β ≈ ?3.6 × 10^?5 K^?1 (90–110 K) at x = 0.24] is triggered by embedding ferromagnetic (F) clusters into the antiferromagnetic (AF) matrix. The strongest MVE is found near the boundary between F and AF phases in the phase diagram, indicating the essential role of competition between the F‐clusters and the AF‐matrix. Furthermore, the MVE is not limited to the PrBaCo₂O_5.5+x but is also observed in the NdBaCo₂O_5.5+x . The present study provides a new approach to obtaining MVE and offers a path to the design of NTE materials.     

A nanowire-based shift register for display scan drivers

The development of display scan drivers is an essential step in the effort to develop transparent and flexible display devices based on nanowire transistors. Here we report a transparent nanowire-based shift register that functions as the standard logic circuit of a display scan driver. To form the shift register circuits using only n-type nanowire transistors, a novel circuit structure was introduced to avoid the output voltage drop typical of purely n-type circuits. A circuit simulation based on the measured nanowire transistor characteristics was developed in the planning phase to verify the circuit operation of the shift register. The shift register successfully produced an output of 0-3 V without an output voltage drop while applying an input of 3 V peak to peak. In addition, the shift register was designed to have multiple channels with a randomly oriented nanowire placement method to enhance the operation yield.     

Enhanced brightness and efficiency of organic light-emitting diodes with an LiF in the Alq/sub 3/

Highly efficient and bright organic light-emitting diodes have been realized by inserting a thin insulating lithium fluoride (LiF) layer in the tris-(8-hydroxyquinoline) aluminum (Alq/sub 3/) with conventional organic layers. By comparing the performances of newly devised devices as a function of the position of the LiF in the Alq/sub 3/ layer, the authors propose the optimal position of the LiF in the Alq/sub 3/ layer. Experimental results show that the efficiency and brightness of the newly devised device with LiF in the Alq/sub 3/ layer were seven times higher than that without LiF in the Alq/sub 3/ layer.     

Silica-coated dual-tube zirconia induction furnace for high-strength optical-fibre production

The dual-wall zirconia induction furnace consists of an inner susceptor tube and an outer insulation tube. The centre piece of the inner tube is coated with a thin silica film. The performance of the newly designed furnace was evaluated in terms of the strength of drawn fibres. The proof test of 47 km length of fibre demonstrated superb strength results, yielding the average survival length at 1·4 GN/m2 (200 klb in?2) to be ~8 km.