Computational Science and Its Applications – ICCSA 2010

This paper designs a loop reduction scheme and measures its performance for the wireless process control application running on the grid-style traffic light network, aiming at improving the response time of the control system. Based on the WirelessHART standard, which assigns a slot to each (sender, receiver) pair according to the routing schedule, the allocation scheme puts all the pairs having no interference to a single slot, reducing the loop length. For further reduction, the classic Dijkstra’s shortest path algorithm is modified such that the number of end-to-end paths starting from the horizontal links and the vertical link, respectively, is almost same. The transmission of the controller, which initiates all message delivery and is the main bottleneck point, will not be blocked. The simulation result demonstrates that the proposed scheme can significantly reduce the control loop length, and the modified path finding algorithm further achieves about 9.8 % improvement, just sacrificing the 3.2 % of transmission success ratio.

This paper designs an intensively measures the performance of an efficient message switch scheme for the intersection area where routing decision may be complex due to traffic concentration, aiming at enhancing end-to-end delays and reliability for the information retrieval service in the vehicular network. Installed at the corner of an intersection, each switch node opens an external interface to exchange messages with vehicles proceeding to the intersection as well as switches the received messages via the dual-channel internal interfaces. Based on the slot-based MAC, at each slot time of internal interfaces, the sender node probes the channel status of the two different destinations and then dynamically selects the appropriate channel according to the probing result. The simulation result shows that the proposed scheme improves the delivery ratio by up to 18.5 % for the experimental channel error rate range as well as up to 8.1 % for the given network load distribution.

In this paper, we propose a novel code acquisition scheme called modified multiple-shift (MMS) for optical code division multiple access (CDMA) systems. By using the modified local code whose sign is positive or negative, the proposed MMS scheme provides a shorter mean acquisition time (MAT) than the conventional multiple-shift (MS) scheme. The simulation results demonstrate that the MAT of the MMS scheme is shorter than that of the MS scheme in both single-user and multi-user environments.

The conventional ultra-wideband (UWB) synchronization schemes could cause poor performance in receiver operations such as demodulation after the synchronization, since unreliable timing information corresponding to low-power multipath components might be transferred to the next stage. To solve this problem, in this paper, we propose novel synchronization schemes for UWB systems. We first derive an optimal scheme based on the maximum likelihood (ML) criterion and then develop a simpler suboptimal scheme. Simulation results show that both proposed schemes provide a better synchronization performance over the conventional scheme.

In cooperative communications, relay usually forwards a full information of source data as received. Unlike this approach, this paper proposes a new relaying scheme based on multi-layered superposition coding with multiple antennas which forwards only partial information of superposed layer(s) on top of basic layer(s) of the source data. Fast forwarding of the partial information results in an increase in overall capacity. Simulation results are presented to show the superiority of the proposed scheme over full information relaying and direct transmission.

This paper measures and analyzes the performance of the hybrid prefetch scheme for gateways on the vehicular telematics network where every information is indexed by the link (street) ID, via simulation using a discrete event simulator. Combining the classic LRU and FAR techniques, the hybrid scheme groups links according to whether they are referenced during the given time interval or not, orders by the Euclidean distance in each group, and fetches the referenced set first. The exensive experiment results demonstrate that 1) the hybrid scheme can improve the request-level instant reply ratio by up to 20.3 %, overcoming 20 % loss of record-level hit ratio, compared with LRU, 2) this scheme outperforms other spatial-locality-based schemes at all satisfiability ranges and LRU when the satisfiability is above 0.8, also showing stable reply ratio for the practical time tolerance range, 3) it quickly stablizes after the prefetch memory initialization and is less affected by the hourly data access pattern change, maintaining steady instant reply ratio for the number of records in each request.

In this paper, soft Fractional Frequency Reuse (FFR) is considered to reduce the co-channel interference and also guarantee the cell edge users data rate. We apply power control in soft FFR and investigate the system performance. Soft FFR divides whole frequency band into multiple subbands with different kinds of transmission power levels and allocates subband according to SINR of cell users. By controlling allocated powers, we can increase the frequency efficiency by using the whole frequency band and also improve the data rate for the cell edge users remarkably by reducing the co-channel interference. If the throughput requirement for the outer region is small, we decrease the power allocated to the outer region which can save power energy while high overall system throughput is achieved.

Recently, Wireless Local Area Network (WLAN) is used by enterprises, government, and the military, as well as small office and home offices. Although it is convenient, it has inherent security weaknesses due to wireless characteristics. For this reason, security-sensitive groups are still unwilling to use WLAN. There are several types of attacks to degrade the wireless network throughput using security weakness, especially Protocol Jamming Attacks are critical. These attacks consume little energy and can be easily implemented. In this paper, we introduce Authentication-based Medium Access Control (A-MAC) to prevent Virtual Carrier Sense (VCS) Jamming Attack and De-authentication / Disassociation Jamming Attack that are typical Protocol Jamming Attacks in 802.11 based wireless systems. The proposed scheme can authenticate frames using Universal Hashing Message Authentication Codes (UMAC-32) and Hidden Sequence Number (SN). A-MAC frequently changes the key and SN using shift row and shift column processes to overcome the weakness of short 32 bits hashing codes. A-MAC can achieve integrity, authentication, and anti-replay attack security features. It can prevent Protocol Jamming Attacks that degrade wireless network throughput. Our simulation shows A-MAC can sustain throughput under Protocol Jamming Attacks.

Femtocell is one of the promising technologies for improving service quality and data rate of indoor users. Femtocell is short-range, low-cost, and low-power base stations (BS) installed by the consumer indoors. Even though femtocell can provide improved home coverage and capacity for indoor users, it causes interference to macrocell users when femtocell uses the same frequency band of macrocell. To reduce the interference between macrocell and femtocell, it is needed to analyze the characteristic of macrocell and femtocell considering various interference scenarios. In this paper, we investigate the uplink and downlink capacity of macrocell and femtocell according to the strength of femtocell transmit power and the number of femtocells through simulations. Simulation results show that femtocell transmit power and the number of femtocells affect the performance of macrocell. From the results, we find the adequate femtocell transmit power which minimize the performance degradation of macrocell and femtocell. We also investigate capacities of macrocell and femtocell according to the locations of femtocell BS and macrocell UE.

Femtocells are expected to be one of the emerging technologies for next generation communication systems. For successful deployment of femtocells in the pre-existing macrocell networks, there are some challenges such as the cell planning for interference management, handoff, and power control. In this paper, we focus on frequency planning which can provide interference avoidance for the co-existence of macrocells and femtocells. We propose a novel frequency planning for femtocells in cellular networks using fractional frequency reuse (FFR). We consider downlink performance of cellular systems based on Orthogonal Frequency Division Multiplexing Access (OFDMA), e.g., WiMAX and 3GPP Long Term Evaluation (LTE). Simulation results show that our scheme indeed reduces the effect of additional co-channel interference (CCI) between a given macrocell and deployed femtocells as well as neighboring macrocells.

This paper proposes an approach that extracts the association information from the location data obtained from the real fields but ignored so far. We provide and apply the approach to the real-life location tracking data collected from the Taxi Telematics system developed in Jeju, Korea. The analysis aims at obtaining taxies’ meaningful moving patterns for the efficient operations of them. The proposed approach provides the flow chart which would not only take a glance around the overall analysis process but also help save temporal and economic costs required to employ the same or similar data mining analysis to similar services such as public transportations, distribution industries, and so on. Especially, we perform an association analysis on both of refined data and interesting factors extracted from the elementary analysis. The paper proposes the refined association rule mining process as follow: 1) obtaining the integrated dataset through the data cleaning process, 2) extracting the interesting factors from the integrated dataset using frequency and clustering method, 3) performing the association analysis, 4) extracting the meaningful and value-added information such as moving pattern, or 5) returning the feedback to adjust inappropriate factors. The result of the analysis shows that the association analysis makes it possible to detect the hidden moving patterns of vehicles that will greatly improve the quality of Telematics services considering the business requirements.

In this paper, an efficient inter carrier interference (ICI) cancellation method for cooperative space time block coded orthogonal frequency division multiplexing (STBC-OFDM) system is presented. In cooperative STBC-OFDM system, ICI cancellation is needed because ICI due to the separated local oscillators always exists. To solve the complexity problem of matrix inversion operation in zero forcing method which shows the best performance, ICI cancellation method using sparse matrix decomposition (SMD) has been proposed. However, overall complexity is increased in proportion to the third order of required tap size which also increases in proportion to FFT size or carrier frequency offsets (CFOs). Considering implementation issue, the conventional method still has not sufficiently overcome the performance versus complexity trade-offs. Therefore, we propose an ICI cancellation method that focuses on solving practical complexity problem of conventional method. The proposed method adaptively decides the required tap size of each sparse matrix through signal to interference and noise ratio (SINR) measurement to reduce the complexity of conventional method, and we verified that the proposed method improves the performance versus complexity trade-offs compared with conventional method.

Due to the fact that most of the sensor network applications are based on the location information of sensor nodes, localization is an essential research area. Some localization schemes in the literature require sensor nodes to have additional devices to measure the distance or angle between two sensor nodes, but it is not suitable for low-cost sensor nodes. On the other hand, other localization schemes use only the connectivity information of sensor nodes so that localization is not much accurate enough. In this paper, we propose a range-free localization scheme, called

Low-cost Two-hop Anchor Node-based Distributed Range-free Localization (LADL)

, which offers a higher accuracy with lower cost than the previous works. LADL exploits a small portion of anchor nodes which know their own location beforehand. In LADL, sensor nodes collect the location information of the anchor nodes within two-hop distance and calculate their own location using a grid-scan algorithm. The simulation results show that LADL has a maximum of 12% lower delivery cost of location information messages and 25% higher accuracy than DRLS [8].

Clustering scheme enabling the efficient utilization of the limited energy resources of the deployed sensor nodes can effectively prolong lifetime of wireless sensor networks. Like most of the protocols for wireless sensor networks, a clustering scheme is vulnerable to a number of security attacks. Especially, attacks involving cluster-heads are the most damaging since cluster-based schemes rely on their cluster-heads for routing and data aggregation. Several studies have proposed a secure clustering scheme and a resilient cluster leader election protocol in wireless sensor networks. However, most of resilient clustering schemes do not support dynamic clustering and most of secure clustering schemes are not robust and resilient against node(specially, cluster-heads) capture. In this paper, we present a secure and resilient clustering protocol on the basis of dynamic clustering protocol. Our scheme provides both a secure clustering and a resilient cluster-head election preserving dynamic clustering unlike the existing secure clustering schemes. In addition, our scheme provides data privacy through the concealed data aggregation. The analysis shows that our scheme offers the security services against both an inside attack and an outside attack while having the little memory, computation and communication overheads. The comparison with related works shows that our scheme has a great improvement in security and the reduction of the overheads compared to the existing schemes.

Femtocells are low-cost and low-power cellular home base stations that connect mobile users to a operator’s network by means of a broadband backhaul. Through this approach, the network operators can extend indoor coverage at a low-cost and reduce the operating cost. However, there exists a co-channel interference between macrocell and femtocells when they use the same frequency band. This co-channel interference causes severe performance degradation of femtocells and macrocell. Therefore, we propose a novel scheme to reduce the co-channel interference to macrocell without performance degradation of femtocells. The proposed scheme avoids the co-channel interference to macrocell users effectively using the SPA antenna which offers 8-directions to control the antenna beam pattern and transmitting power. Performance evaluation results have confirmed that the proposed scheme reduces the co-channel interference by 80% compared to the case using omni-directional antenna.

Remarkable wireless networks technology developments have made us to expect the realization of new applications like the advanced traffic system, the disaster prevention system, and the adhoc network system. However the resources of wireless bandwidths are not enough to use for such new applications because it is not efficient usage. Therefore, it is necessary to develop with new efficient wireless transmission methods like cognitive wireless network. In this paper, the transmission control methods in cognitive wireless network considering with cross layers including user policies are discussed. First, at the observation stage, the physical data such as user policy, electric field strength, bit error rate, jitter, latency, packet error rate, and throughput are observed. Then, at the decision stage, AHP (Analytic hierarchy process) is applied for decision making process with those parameters. Finally, the action stage, one of the suitable link is chosen and changed links and networks.

In the simulation, ns2 are used for the computational results to the effectiveness of the suggested transmission methods in cognitive wireless networks.

This paper aims to develop an integrated model of predicting business failure, using business financial and non-financial factors to diagnose the status of business, thereby providing useful references for business operation. This study applied Rough Set Theory to extract key financial and non-financial factors and Grey Relational Analysis (GRA) as the approach of assigning weights. In addition, Case-Based Reasoning (CBR) are adopted to propose a new hybrid models entitled RG-CBR (combining RST and CBR with GRA) to compare the accuracy rates in predicting failure. After exploring the TEJ (

Taiwan Economic Journal)

database and conducting various experiments with CBR, RST-CBR and RG-CBR the study finds CBR, RST-CBR and RG-CBR reporting an accuracy rate in predicting business failure of 49.2%, 59.8% and 83.3%respectively. The RG-CBR boasts the highest accuracy rate while also effectively reducing Type I and Type II error rates.

Optical microscopy image analysis is important in the life science research. To obtain the motion of the cell, we use the viscous fluid registration method based on fluid dynamics. Viscous fluid registration deforms an image at time

t

to the next image at time

t

+1. In this algorithm, there is a problem that an object cannot be divided into two. In other words, the divided objects from one are connected by thin line because the velocity field on the connected thin line is zero. To solve this problem, we suggest a new viscous fluid registration algorithm for the object division. This algorithm is only added similarity maximization step to correct the displacement in the near pixels in the original viscous fluid registration. Using this method, one object is divided into two, and divided objects are not connected. We experiment the anaphase detection based on a nucleus identification using laser scanning microscope HeLa cell images. Experimental result shows that 74 in 76 cells are tracking well and 6 cells in the anaphase are detected. In three scenes in the cell division which can not be divided into two using original viscous fluid registration, suggested algorithm can be divided into two cells completely.

In previous paper, we introduced a concept of multi-soft sets and used it for finding reducts. However, the comparison of the proposed reduct has not been presented yet, especially with rough-set based reduct. In this paper, we present matrices representation of multi-soft sets. We define AND and OR operations on a collection of such matrices and apply it for finding reducts and core of attributes in a multi-valued information system. Finally, we prove that our proposed technique for reduct is equivalent to Pawlak’s rough reduct.

Two clustering techniques of water quality for canals in Bangkok were compared: K-means and Fuzzy c-means. The result illustrated that K-means has a better performance. As a result, K-means cluster was used to classify 24 canals of 344 records of surface water quality within Bangkok; the capital city of Thailand. The data was obtained from the Department of Drainage and Sewerage Bangkok Metropolitan Administration during 2005-2008. Water samples were collected and analyzed on 13 different parameters: temperature, pH value (pH), hydrogen sulfide (H

2

S), dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), substance solid (SS), total kjeldahl nitrogen (TKN), ammonia nitrogen (NH

3

N), nitrite nitrogen (NO

2

N), nitrate nitrogen (NO

3

N), total phosphorous (T-P) and total coliform. The data were analyzed and clustered. The results of cluster analysis divided the canals into five clusters. The information from clustering could enhance the understanding of surface water usage in the area. Additionally, it can provide the useful information for better planning and watershed management of canals in Bangkok.

Mobile Ad hoc Networks (MANETs) have witnessed an increasing amount of interest during the last decade. Hosts (or nodes) within the network are mobile, and each node is equipped with a short range transmitter and receiver, antenna, and local power supply. Nodes then operate as a router to relay messages from the sender to the receiver, and they can be organised into different topologies; for example: they can be flat or hierarchical, they can move in any direction and speed, and they can communicate with each other through wireless routing protocols. More recently, systems based on Ultra-WideBand (UWB) technology have become a promising candidate in application to MANETs. This is mainly due to their powerful capabilities, such as their high data rates and low power consumption, and although many routing protocols have been designed for ad-hoc networks, few have considered their application to UWB based MANETs. This paper presents a review of different types of wireless routing protocols for MANETs with a concluding emphasis on their application to UWB based systems.

Wireless mesh networks (WMNs) have emerged as a key technology for next generation wireless networks showing rapid progress and inspiring numerous applications. The persistence driving force in the development of WMNs comes from their envisioned advantages including extended coverage, robustness, self-configuration, easy maintenance, and low cost. However, to support real-time applications with stringent quality of support (QoS), WMNs must be equipped with a robust, reliable and extremely efficient routing protocol so that packets can be routed through them with minimum delay. In this paper, we focus on the critical factors in designing a routing protocol for WMNs, and propose an efficient and reliable routing protocol. The protocol is based on a reliable estimation of available bandwidth in a wireless path and end-to-end delay measurements. Simulations carried out on the protocol demonstrate that it is more efficient than some of the current routing protocols.

In agricultural processes, many works may need to be automated, because those are very hard labors or time-consuming jobs for farmers. Workflow technologies, which have successfully been a good model for a service automation in various computing environments, can be used as a possible service automation model in agriculture. A workflow for u-agriculture may need various contexts sensed from real sensor networks for service automation. Recently, many researches have applied workflow technologies into the various fields such as smart home, u-health care, u-city, u-port, and u-agriculture. However, many current workflow service have difficulty to control work processes and execute services according to context information in u-agricultural environment. This paper proposes a context-aware service model for u-agriculture, which is based on workflows and is aimed at supporting smart workflow services based on ubiquitous sensor networks in u-agriculture. With the proposed context-aware service model, developers can easily integrate various service demands into a service workflow, and can easily develop a context-aware workflow service for u-agriculture. Therefore, the proposed service model can be greatly helpful in the development of smart applications or the work automation in the fields of u-agriculture.

As computer and network technology advance, multimedia data can be transferred in real time on the Internet. The increasing user demands for various multimedia data make VOD (Video-on-Demand) services to be developed. VOD services are being used in lots of fields, such as entertainment, distance learning, home shopping, and interactive news. In comparison to the existing HTTP services, these VOD services have special features that the time for their services is longer and the services request more disks and network bandwidths. Therefore, compared to HTTP service environments, VOD services have some different workload patterns. In these VOD service environments, the existing load balancing algorithms researched before are not proper. In this paper, we propose a new load balancing algorithm that is based on the history of past user access patterns to make server loads even on hierarchically distributed VOD system environments. This algorithm uses a dynamic genetic algorithm. The proposed distributed VOD system environment consists of a number of VOD servers, which are distributed geographically, and control servers that manage each group of VOD servers. User requests are distributed to prevent convergence by distributing VOD servers geographically. We use a genetic algorithm based on history data to distribute user requests in a local service area. The information of user requests and services is stored and referred in a database as history data. By applying these history data to the fitness function of genetic algorithms, we implemented the genetic algorithm and operations for VOD systems. The load balancing algorithm proposed in this paper can distributed workloads by predicting workloads precisely on VOD environments.

Wireless sensor networking has been a subject of extensive research efforts in the recent years, and has been well recognized as a ubiquitous and general approach for some emerging applications such as a real-time traffic monitoring, ecosystem and battlefield surveillance. Since these networks deal with sensitive data, it is imperative that they are made secure against various types of attacks such as node capture, physical tampering, eavesdropping, denial of service etc. This paper presents a secure routing mechanism for wireless sensor networks. The protocol is resilient in the presence of malicious nodes that may launch selective packet dropping attack on the routing path. The scheme employs single-path routing, and therefore, it is energy-efficient. While the packets are forwarded towards the base station, if any node fails to forward a packet, it is isolated immediately. Packets are then routed around the node. Simulation conducted on the scheme clearly demonstrates that it is more efficient than some of the existing similar schemes.

Key establishment and management are the cores of many security mechanisms and services in wireless sensor networks which are commonly deployed in a hostile environment. Pre-distributing keys into sensor nodes is a practical option for key management in wireless sensor environment. The negotiation and establishment of pairwise keys are much more important after the nodes are deployed, so that the whole network will work in expectation and safely. In this paper, we proposed an efficient pairwise key establishment scheme used in cluster-based random key pre-distribution protocol, which can provide perfect connectivity and security for large scale wireless sensor networks. Simulation results and performance analysis indicates that it also has other strongpoint, lower communication and computational overhead, much more scalable and flexible for the network size, a better balance between the node storage capacity and communication overhead.

An ad-hoc network is a special kind of network, where all of the nodes move in time. So the topology of the network changes as the nodes are in the proximity of each other. Ad-hoc networks are generally self-configuring, because of the concept of no stable infrastructure takes a place. The research is focused in Wireless (Ad-Hoc) Mesh Networks. In this network, each node should help relaying packets of neighboring nodes using multi-hop routing mechanism. This deployment is needed to reach far destination nodes to solve problem of dead communication. This multiple traffic "hops" within a wireless mesh network caused dilemma. It can extend the coverage area, but the repeatedly relayed traffic will exhaust the radio resource. Wireless mesh networks that contain multiple hops become increasingly vulnerable to problems such as energy degradation and rapid increasing of overhead packets. Minimizing hop or relay is expected to solve this dilemma.

Nodes in a wireless sensor network are susceptible to various attacks primarily due to their nature of deployment. Therefore, providing security to the network becomes a big challenge. We propose a scheme considering cluster architecture based on LEACH protocol to build a security mechanism in a query-processing paradigm within wireless sensor network. The scheme is capable of thwarting replay attack while ensuring essential properties of security such as authentication, data integrity and data freshness. Our scheme is lightweight as it employs symmetric key cryptography with very short-length key. We simulate our scheme to show its efficacy of providing basic security to the network as well as detecting replay attack in the sensor network. Further we compare our scheme with one of the existing schemes taking packet loss and packet rejection ratio as performance metrics.

Sensing the same region of a physical environment by many sensor nodes results in wastage of energy. This behavior conflicts with the most important requirement of a wireless sensor network which is power efficiency. Thus, it is essential to have a mechanism to eliminate high redundancy while preserving an acceptable level of network coverage. In this paper, we review the proposed protocols in the literature that aim to eliminate the sensing redundancy in wireless sensor networks.

In wireless sensor networks, sensor nodes are generally distributed in hostile environments so the security services such as confidentiality, authentication and integrity are very important. The basis of these security services is the key management. The majority of key managements use the random key pre-distribution mechanism based on the probability model. Thus, an adversary can easily get the keys between any two non-compromised nodes by compromising some number of nodes. If the adversary gets the keys, he can modify or insert messages into the communication channels. These kinds of attacks are very critical because the adversary may mislead the operation of the networks or the application. Recently, Liu and Dong proposed a method to detect the keys which is misused by an adversary. They suggested the additional protection for non-compromised sensor nodes even if an attacker has learned the shared key between them. To detect a misused key, the traffic overhead is inevitable but their method has some inefficient aspects by performing a unidirectional misused key detection and generating unnecessary traffic. In this paper, we enhance the misused key detecting mechanism by detecting a misused key bidirectionally and removing the unnecessary traffic while the security functionality of the Liu and Dong’s scheme is preserved. Our simulation shows that the energy consumption of our scheme is 36% more efficient than that of the Liu and Dong’s scheme on average.

An accountable disaster prediction and the appropriate forewarned time are the key issues to reduce the possible damages. Around the globe, landslides and mudslides are serious geological hazards affecting people, and cause significant damages every year. The stability of a slope changed from a stable to an unstable condition that spawns a landslide or mudslide. In most of mudslide-damaged residences, the electricity equipments, especially electricity poles, are usually tilted or moved. Since the location and status of each electricity pole are usually recorded in AMI (Advanced Metering Infrastructure) MDMS (Meter Data Management System), AMI communication network is a substantial candidate for constructing the mudslide detection network. To identify the possible mudslide areas from the numerous gathered data, this paper proposes a data analysis method that indicates the severity and a mechanism for detecting the movement. According the detecting result and the gathered data, this study calculates the remaining forewarned time when an anomaly happens.

Most existing works in ontology deployment within the health industry are mainly focusing on the standardization and interoperability goals. In this paper, we propose the utilization of an ontology to apply a new constraint in health archetypes, i.e. the slot filling constraint. An archetype is a model that represents functional health concept such as

admission record

. It can reuse other existing archetypes through a slot. The name of a slot represents a more specific health concept such as

head

. The slot filling constraint restricts the selection of archetypes to fill in that specific slot so that only relevant archetypes are chosen from the available ones. Ontology is used to enforce this constraint. An approach on how to apply the constraint is presented based on the semantic similarity/relevance concept. The evaluation shows that the approach is a better alternative to the current slot filling process which depends on manual decision by the archetype author.

Distributed enterprise applications are typically based on a multiple–tier client–server architecture where large volume of data is transferred between tiers frequently. When the amount and frequency of data to be transferred become large, network bandwidth will become a bottleneck and efficient middle–tier data management is critical. In this paper, we propose a semi–persistence model to capture the evolving nature of data in a middle tier data management system. We also propose to use Bloom Filters (BF) as an efficient data structure to maintain the time-sensitive frequency profile of the underlying data items. We first extend the standard Bloom Filters by replacing the bit-vector with an array of counters. We then optimize it by allocating lowest space necessary for each counter to store its value. The preliminary experiments show that the optimized BF achieves considerable improvement on space usage while providing the same results of frequency profile.

Computational models of the artificial intelligence such as soft set theory have several applications. Parameterization reduction under soft set theory can be considered as a technique for medical decision making. One possible application is the decision making of patients suspected influenza. In this paper, we present the applicability of soft set theory for decision making of patients suspected influenza. The proposed technique is based on maximal supported objects by parameters. At this stage of the research, results are presented and discussed from a qualitative point of view against recent soft decision making techniques through an artificial dataset.

The problem of identifying a person using biometric data is interesting. In this paper, the uniqueness of EEG signals of individuals is used to determine personal identity. EEG signals can be measured from different locations, but too many signals can degrade the recognition speed and accuracy. A practical technique combining Independent Component Analysis (ICA) for signal cleaning and a supervised neural network for classifying signals is proposed. From 16 EEG different signal locations, four truly relevant locations

F

7

,

C

3

,

P

3

, and

O

1

were selected. This selection can identify a group of 20 persons with high accuracy.

Many techniques in the process of document retrieval and clustering, based on the vector space model, represent documents by vectors. They ignore the conceptual relationships of terms such as synonyms, hypernyms and hyponyms and, especially, treat terms as a

bag of terms

. The application of conceptual relationships of terms has been proved by generating improved results for document clustering in previous studies. For those studies, thesauri like WordNet were used to provide the information of relationships between terms. However, some domain-specific terms like "query expansion" and "document clustering" cannot be found in these thesauri. These terms are thought of as important features in domain-specific documents. In this paper, we propose an automatic domain-specific thesaurus building approach based on Formal Concept Analysis (FCA) dealing with the problem with general thesauri. We also apply the domain-specific thesaurus as background knowledge to represent documents by concept dimension vectors. In the evaluation, an improved result by our method compared to traditional approaches is shown.

Among similarity search indexes, the

D-index

introduced by Gennaro et al. in 2001 is regarded as an efficient metric access method. The performance of this index depends on several parameters, and their optimal configuration remains an open problem. We study two performance issues that occur when the D-index handles high dimensional objects. To solve these problems, we introduce an optimization that simplifies the D-index. By doing this, we remove two configuration parameters and improve performance.

Automatic Chinese text classification is an important and well-known research topic in the field of information retrieval and natural language processing. However, past researches often ignore the problem of word segmentation and the relationship between words. This paper proposes an

N

-gram-based language model for Chinese text classification which considers the relationship between words. To prevent from the out-of-vocabulary problem, a novel smoothing method based on logistic regression is also proposed to improve the performance. The experimental result shows that our approach outperforms the previous

N

-gram-based classification model above 11% on micro-average F-measure.

Quasigroups are a well-known combinatorial design equivalent to more familiar Latin squares. Because all possible elements of a quasigroup occur with equal probability, it makes it an interesting tool for the application in computer security and for production of pseudorandom sequences. Prior implementations of quasigroups were based on look-up table of the quasigroup, on system of distinct representatives etc. Such representations are infeasible for large quasigroups. In contrast, presented analytic quasigroup can be implemented easily. It allows the generation of pseudorandom sequences without storing large amount of data (look-up table). The concept of isotopy enables consideration of many quasigroups and genetic algorithms allow efficient search for good ones.

The ubiquitous computing era has pushed the Architecture, Engineering, and Construction (AEC) industry towards new frontiers of digitally enabled practice. Are these the frontiers originally identified by the pioneers in the field? Architectural design has progressively shifted from two-dimensional paper based pencil sketched models to digital models drawn in various Computer-Aided Design (CAD) tools. The recent adoption of parametric modeling tools from the aerospace industry has been driven by the need for tools that can assist in rapid flexible modeling. The adaptation of parametric modeling has reformed both pedagogy and practice of architectural design. The question remains if parametric design has answered all the requirements specified by Steven Anson Coons in his 1963 proposal for a Computer-Aided Design (CAD) system. Given the growth of computational power and ubiquitous computing, how has CAD met the visions of its pioneers with respect to the flexibility and ease of communication with the computer and support of simultaneous design conversations with many designers working on the same project? This paper will revisit ideas conceived by the early inventors of CAD, explore the opportunities for advancing parametric modeling with the existing ubiquitous computing infrastructure, and introduces the notion of software openness to support creativity and multidisciplinary design integration.

Since most of the existing simulation researches on shape memory alloys are focused on their static behavior, the simulation of their dynamic response behavior is the blank field waiting for researchers to explore. In this paper, both one-dimensional and three-dimensional dynamic simulations, as well as an improved simulation model for shape memory alloys’ cyclic response behavior will be discussed. The validity of the dynamic and cyclic response simulation model is illustrated by comparing the calculated results with the experiment data. The damping capacity of shape memory alloys is also demonstrated in both one- and three-dimensional simulations.

In this paper an adaptive fuzzy filter, based on fuzzy system, is proposed for speech signal enhancement and automatic speech recognition accuracy. In the past two decades the basic wavelet thresholding-algorithm has been widely studied and is common applied to filter noise. In the proposed system adaptive wavelet thresholds are generated and controlled by fuzzy rules concerning the presence of speech in noise. First an amplified voice activity detector is designed to improve performance on SNR lower than 5dB. Then an adaptive threshold decision module based on fuzzy inference system is proposed. In this fuzzy inference system overall relations between speech and noise are summarized into seven fuzzy rules and four linguistic variables, which are used to detect the state of signals. The adaptive threshold and membership functions are optimally obtained by particle swarm optimization algorithm so the SNR of the filter output for training signal data can be maximized. Experimental results reveal that our proposed system effectively increases the SNR and the recognition rate of speech.

Endovascular aneurysm repair (EVAR) is an advanced minimally invasive surgical technology that is helpful for reducing patients’ recovery time and postoperative morbidity. This study proposes an ensemble model to predict postoperative morbidity after EVAR. The ensemble model was developed using a training set of consecutive patients who underwent EVAR between 2000 and 2008. The research outcomes consisted of an ensemble model to predict postoperative morbidity, the occurrence of postoperative complications prospectively recorded, and the causal-effect decision rules. The probabilities of complication calculated by the model were compared to the actual occurrence of complications and a receiver operating characteristic (ROC) curve was used to evaluate the accuracy of postoperative morbidity prediction. In this series, the ensemble of BN, NN and SVM models offered satisfactory performance in predicting postoperative morbidity after EVAR. Moreover, the Markov blankets of BN allow a natural form of causal-effect feature selection, which provides a basis for screening decision rules generated by granular computing.

We have proposed the mapping of graph coloring problems into swarm dynamics. Empirical evidence that flock steering behaviors augmented with the notion of hostility (enmity and friendliness) are enough to perform efficiently the task of coloring the nodes of graphs even in the case 3-coloration hard graph topologies. We discuss here what are the minimal cognitive capabilities that allow the emergent behavior of swarms to solve such NP-complete problem without mediating an explicit knowledge representation.

In Japan, population of aged people is becoming greater. According to it, number of the wheelchair user would become larger. The government has being improved to lessen the barriers for these people. But depending on the physical power of wheel chair users, it was pointed out that there could be the places where they could not move by their physical power. This is a reason that many wheelchair users do not move by their alone. Therefore we tried to develop the navigation system to eliminate the problem. At the beginning we have developed the system to measure the required force to move the wheelchair, the width of the space of aisle where they could turn back the direction, and the position information. By the data base, we planned to develop the navigation system for wheelchair users who could move alone to working places or other places where they want to go. In this paper, we report the system developed to collect data for navigation of wheelchair users.