Showing papers in "Computing and Informatics \/ Computers and Artificial Intelligence in 2005"

The Use of Genetic Algorithms and Neural Networks to Approximate Missing Data in Database.

Abstract: Missing data creates various problems in analysing and processing data in databases. In this paper we introduce a new method aimed at approximating missing data in a database using a combination of genetic algorithms and neural networks. The proposed method uses genetic algorithm to minimise an error function derived from an auto-associative neural network. Multi-layer perceptron (MLP) and radial basis function (RBF) networks are employed to train the neural networks. Our focus also lies on the investigation of using the proposed method in accurately predicting missing data as the number of missing cases within a single record increases. It is observed that there is no significant reduction in accuracy of results as the number of missing cases in a single record increases. It is also found that results obtained using RBF are superior to MLP.

Intelligent computing for the management of changes in industrial engineering modeling processes

Abstract: Advancements in engineering modeling have changed the work of engineers during the last two decades. Sophisticated descriptions store information about shape oriented engineering objects and their relationships. Boundary representations of form features constitute shape models. Rules and checks have replaced simple data form of shape model entity attributes. This change of modeling facilitates a next step towards application of computer intelligence at engineering object related decisions. The authors propose a method of intelligent attribute definition for integrated decision assistance environments of modelling systems. This method provides quick and comprehensive assessment of situations for decisions on modification of modeled objects in very complex information environments. The paper starts with an outline of the approach to intelligent decision assistance by the authors. Next, an Internet portal communicated scenario of the proposed modeling is discussed. Following this, multilevel solution for modeling, adding characteristics for engineering objects, and definitions and communications are detailed as essential methods in the proposed modeling. Finally, behaviors for essential classes of modeled objects and an example for the definition of situations and behaviors represent implementation issues.

Genetic Algorithms as a Model of Musical Creativity - on Generating of a Human-Like Rhythmic Accompaniment.

Abstract: This article introduces a genetic algorithm based system intended for automated generating of a realistic rhythmic (drum set) accompaniment. Present systems do not insist on the natural music criteria and realistic (human-like) result. They generate a rhythmic accompaniment regardless to the other instruments used. The fitness operators are mostly based on manual evaluation by user. The system described in this paper uses automatic fitness evaluator and prefers some of the natural music criteria. Accompaniment is generated with regard to a harmonic-accompaniment instrument (HAI).

Behavioural equivalences on finite-state systems are PTIME-hard

Abstract: The paper shows a LOGSPACE-reduction from the Boolean circuit value problem which demonstrates that any relation subsuming bisimilarity and being subsumed by trace preorder (ie, language inclusion) is PTIME-hard, even for finite acyclic labelled transition systems. This reproves and substantially extends the result of Balcazar, Gabarro and Santha (1992) for bisimilarity.

Invariant Object Recognition Using Radon-based Transform

Abstract: The properties of the Radon transform are used to derive the transformation invariant to translation, rotation and scaling The invariant transformation involves translation compensation, angle representation and 1-D Fourier transform The new object recognition method is studied experimentally in two domains, mammogram labels recognition and face recognition For mammogram labels, the recognition accuracy is 97 %, while in case of faces it reaches 96 %

Genetic algorithm for solving uncapacitated multiple allocation hub location problem

Abstract: Hub location problems are widely used for network designing. Many variations of these problems can be found in the literature. In this paper we deal with the uncapacitated multiple allocation hub location problem (UMAHLP). We propose a genetic algorithm (GA) for solving UMAHLP that uses binary encod- ing and genetic operators adapted to the problem. Overall performance of GA implementation is improved by caching technique. We present the results of our computational experience on standard ORLIB instances with up to 200 nodes. The results show that GA approach quickly reaches all optimal solutions that are known so far and also gives results on some large-scale instances that were unsolved before. � This research was partially supported by the Serbian Ministry of Science and Ecology under project 144007. The authors are grateful to Andreas Ernst, Sergio Garc´oa Quiles and Haluk Topcuoglu for useful communication and sending us fixed costs for large-scale UMAHLP instances.

Efficient graph coloring with parallel genetic algorithms

Abstract: In this paper a new parallel genetic algorithm for coloring graph vertices is presented. In the algorithm we apply a migration model of parallelism and define two new recombination operators SPPX and CEX. For comparison two problem- oriented crossover operators UISX and GPX are selected. The performance of the algorithm is verified by computer experiments on a set of standard graph coloring instances.

Collaborative Environment for Grid-based Flood Prediction.

Abstract: This paper presents the design, architecture and main implementation features of the flood prediction application of the Task 1.2 of the EU IST CROSSGRID project. The paper begins with the description of the virtual organization of hydrometeorological experts, users, data providers and customers supported by the application. Then the architecture of the application is described, followed by used simulation models and modules of the collaborative environment. The paper ends with vision of future development of the application.

Supporting a Closely Coupled Task between a Distributed Team: Using Immersive Virtual Reality Technology.

Abstract: Collaboration and teamwork is important in many areas of our lives. People come together to share and discuss ideas, split and distribute work or help and support each other. The sharing of information and artefacts is a central part of collaboration. This often involves the manipulation of shared objects, both sequentially as well as concurrently. For coordinating an efficient collaboration, communication between the team members is necessary. This can happen verbally in form of speech or text and non-verbally through gesturing, pointing, gaze or facial expressions, where shared objects and the environment may be involved too. Collaborative Virtual Environments (CVE) allow remote users to come together and interact with each other and virtual objects within a computer simulated environment. Immersive display interfaces, such as a walk-in display, that place a human physically into the synthetic environment lend themselves well to support a natural manipulation of objects as well a set of natural non-verbal human communication, as they capture the motion of the user’s head and hand. Communication of tracking data, however, can saturate the network and result in delay or loss of messages vital to the manipulation of shared objects. This extends our research in [27]. This paper investigates the reality of shared object manipulation between remote users collaborating through linked walk-in displays. Various forms of shared interaction are examined through a set of structured subtasks within a representative construction task. We report on extensive user-trials between three walk-in displays in the UK and Austria linked over the Internet using a CVE, and demonstrate such effects on a naive implementation of a benchmark application the Gazebo building task. We then present and evaluate application-level workarounds and conclude by suggesting solutions that may be implemented within next-generation CVE infrastructures.

A (t, n) Threshold Secret Sharing System with Efficient Identification of Cheaters

Abstract: In this paper, we propose a new (t, n) threshold scheme. The scheme allows a user to divide portions of a secret among the designated group. Any t or more participants from a designated group of n members can cooperate to reconstruct the secret while (t-1) or less participants can not. Furthermore, the scheme provides an efficient mechanism to detect and identify cheaters. From the security analysis, we conclude that any participant does not have the ability to deceive other participants to obtain their portion of the secret. Therefore, this scheme is very practical for a broad spectrum of applications.

Object Replication Algorithms for World Wide Web.

Abstract: Object replication is a well-known technique to improve the accessibility of the Web sites. It generally offers reduced client latencies and increases a site’s availability. However, applying replication techniques is not trivial and a large number of heuristics have been proposed to decide the number of replicas of an object and their placement in a distributed web server system. This paper presents three object placement and replication algorithms. The first two heuristics are centralized in the sense that a central site determines the number of replicas and their placement. Due to the dynamic nature of the Internet traffic and the rapid change in the access pattern of the World-Wide Web, we also propose a distributed algorithm where each site relies on some locally collected information to decide what objects should be replicated at that site. The performance of the proposed algorithms is evaluated through a simulation study. Also, the performance of the proposed algorithms has been compared with that of three other well-known algorithms and the results are presented. The simulation results demonstrate the effectiveness and superiority of the proposed algorithms.

Non-direct encoding method based on cellular automata to design neural network architectures

Abstract: Architecture design is a fundamental step in the successful application of Feed forward Neural Networks. In most cases a large number of neural networks architectures suitable to solve a problem exist and the architecture design is, un- fortunately, still a human expert's job. It depends heavily on the expert and on a tedious trial-and-error process. In the last years, many works have been focused on automatic resolution of the design of neural network architectures. Most of the methods are based on evolutionary computation paradigms. Some of the designed methods are based on direct representations of the parameters of the network. These representations do not allow scalability; thus, for representing large architectures very large structures are required. More interesting alternatives are represented by indirect schemes. They codify a compact representation of the neural network. In this work, an indirect constructive encoding scheme is proposed. This scheme is based on cellular automata representations and is inspired by the idea that only a few seeds for the initial configuration of a cellular automaton can produce a wide variety of feed forward neural networks architectures. The cellular approach is ex- perimentally validated in different domains and compared with a direct codification scheme.

Collaborative virtual environment for advanced computing

Abstract: Synchronous collaborative systems allow geographically distributed participants to form a virtual work environment enabling cooperation between peers and enriching the human interaction. The technology facilitating this interaction has been studied for several years and various solutions can be found at present. In this paper, we discuss our experiences with one such widely adopted technology, namely the Access Grid. We describe our experiences with using this technology, identify key problem areas and propose our solution to tackle these issues appropriately. Moreover, we propose the integration of Access Grid with an Application Sharing tool, developed by the authors. Our approach allows these integrated tools to utilise the enhanced features provided by our underlying dynamic transport layer.

A Hierarchical Component-based WebGIS and Its Key Technologies

Abstract: A practical hierarchical component-based WebGIS model referred to as Geo-Union is presented. Geo-Union consists of four layers: storage layer, ser- vice layer, component layer and application layer. Service layer is partitioned into another two layers: Geo-Union client and Geo-Union server. The architectures and object diagram of each layer in Geo-Union are discussed in details. After that, four key technologies adopted in Geo-Union (spatial data model, ORDB, spatial index and spatial cache) are summarized and analyzed, especially the spatial cache frame- work of Geo-Union. At last, some future works in WebGIS, such as interoperability, security, distributed computing and intelligent computing, are indicated and simply explored.

Development of threat evaluation tool for distributed network environment

Abstract: Current information protection systems only detect and warn against individual intrusion, and are not able to provide a collective and synthesized alert message. In this paper, we propose a new Meta-IDS system which is called "SIA System". The SIA system can filter redundant alert messages, analyze mixed at- tacks using correlation alert messages from each sensor and respond to security threats quickly, after classifying them into one of four different statuses. Then we implement the SIA system and test the efficiency of it in the managed networks. Thus we confirm that the SIA system enables security managers to deal with secu- rity threats efficiently.

Fuzzy implications and inference processes

Abstract: We define fuzzy implications in general, then study their families defined from t-norms, t-conorms and strong negations. Connections between such implications and negations are established. Some basic results are presented concerning the contrapositive symmetry property. The study gives birth to a new class of t-norms. Members of this family, together with the corresponding R-implications, have attractive properties making them competitive in different applications, especially in fuzzy inference rules.

Production scheduling with complex precedence constraints in parallel machines

Abstract: Heuristic search is a core area of artificial intelligence and the employ- ment of an efficient search algorithm is critical to the performance of an intelli- gent system. This paper addresses a production scheduling problem with complex precedence constraints in an identical parallel machines environment. Although this particular problem can be found in several production and other scheduling applications; it is considered to be NP-hard due to its high computational com- plexity. The solution approach we adopt is based on a comparison among several dispatching rules combined with a diagram analysis methodology. Computational results on large instances provide relatively high quality practical solutions in very short computational times, indicating the applicability of the methodology in real life production scheduling applications.

Fuzzy-Petri-Net Reasoning Supervisory Controller and Estimating States of Markov Chain Models.

Abstract: Markov chain models are efficient tools for representing stochastic discrete event processes with wide applications in decision and control. A novel approach to fuzzy-Petri-net reasoning generated solution to initial or another state in Markov-chain models is proposed. Reasoning is performed by a fuzzy-Petri-net supervisory controller employing a fuzzy-rule production system design and a fuzzy-Petri-net reasoning algorithm, which has been developed and implemented in C++. The reasoning algorithm implements calculation of the degrees of fulfilment for all the rules and their appropriate assignment to places of Petri net representation structure. The reasoning process involves firing active transitions and calculating degrees of fulfilment for the output places, which represent propositions in the knowledge base, and determining of fuzzy-distributions for output variables as well as their defuzzified values. Finally, these values are transferred to assign the state of Markov-chain decision model in terms of transition probabilities.

An Image Retrieval System Based on the Color Complexity of Images

Abstract: The fuzzy color histogram (FCH) spreads each pixel's total membership value to all histogram bins based on their color similarity. The FCH is insensitive to quantization errors. However, the FCH can state only the global properties of an image rather than the local properties. For example, it cannot depict the color complexity of an image. To characterize the color complexity of an image, this paper presents two image features - the color variances among adjacent segments (CVAAS) and the color variances of the pixels within an identical segment (CVP- WIS). Both features can explain not only the color complexity but also the principal pixel colors of an image. Experimental results show that the CVAAS and CVPWIS based image retrieval systems can provide a high accuracy rate for finding out the database images that satisfy the users' requirement. Moreover, both systems can also resist the scale variances of images as well as the shift and rotation variances of segments in images.

Integration of Soft Computing and Fractional Derivatives in Adaptive Control

Abstract: Realizing that generality and uniformity of the usual Soft Computing (SC) structures exclude the application of plausible simplifications relevant in the case of whole problem classes resulted in the idea that a novel branch of soft computing could be developed by the use of which far simpler and more lucid uniform structures and procedures could be applied than in the traditional ones. Such a novel approach to computational cybernetics akin to SC was developed at Budapest Tech to control inaccurately and incompletely modelled dynamic systems under external disturbances. Hydraulic servo valve controlled differential cylinders as non-linear, strongly coupled multivariable electromechanical tools serve as excellent paradigms of such difficulties. Their control has to cope with the problem of instabilities due to the friction forces between the piston and the cylinder, as well as with uncertainties and variation of the hydrodynamic parameters that makes it unrealistic to develop an accurate static model for them. In this paper a combination of this novel method with the use of fractional derivatives is applied for the control of a hydraulic differential cylinder. Simulation results well exemplifying the conclusions are also presented.

Computing epistasis of template functions through Walsh transforms

Abstract: Manuscript received 21 May 2004; revised 2 May 2005Abstract. Template functions have been introduced as a class of test functions,allowing to study the convergence behaviour of genetic algorithms. In this note,we show how to use Walsh transforms to calculate the normalized epistasis of thesefunctions.Keywords: Genetic algorithm, GA hardness, epistasis, Walsh transform, Fouriertransform, template function

Applying the GWO Model to Relaxed Collaborative Systems

Abstract: Building collaborative applications is still a challenging task. A collaborative application can be viewed as a class of distributed shared memory system. A distinctive property of these systems is their memory consistency model. In this paper, we argue that there is a relationship between different collaboration styles, on the one hand, and different memory consistency models, on the other. In particular, we propose a practical collaboration style, exemplified by a collaborative electronic organizer, that can be supported by the GWO memory consistency model, a rather relaxed model stricter only than local consistency. The advantage of the proposed style is that it reduces the amount of information that must be exchanged among the processors. Because there have been no propositions of the specific rules---i.e., the protocol---that the processors in a system must follow to implement the GWO model, we also propose a protocol that exactly matches the properties of the model.

Twins: scalable 2-hop structured overlay network

Abstract: In this paper we propose a new structured overlay network, which is more efficient and scalable than previous ones. We call it Twins, because its routing table consists of two parts, one containing nodes with common prefix and the other containing nodes with common suffix. Twins routes messages to their destinations in just 2 hops even in a very large scale and the overhead is very low. When deployed in a peer-to-peer system with 5 000 000 nodes, each node receives only 6 messages per second for routing table maintenance. This cost, as well as routing table size, varies as a O(sqrt N) function to the overlay scale, so Twins can also run well in an even larger environment.

Efficient Vertical Handoffs in Wireless Overlay Networks

Abstract: Mobile IP is used to keep track of location information and make the data available to the mobile device anytime, anywhere. It is designed to address the macro-mobility management, it does not address micro-level mobility issues such as handoff latency and packet loss. In this paper, we propose a mobility management scheme to handle the movements of mobile nodes among different wireless network technologies. Our scheme combines: (a) A hierarchical mobility management architecture to hide mobility of mobile nodes within the foreign domain from the home agent; (b) A handoff protocol to reduce packet loss during the transition from one cell to another; (c) The use of our proposed virtual cells in order to reduce the upward vertical handoff latency and disruption as much as possible. Our design is based on the Internet Protocol (IP) and is compatible with the Mobile IP standard (MIP). We also present simulation results showing that our handoff scheme is very fast to meet the requirements of an interactive communication session such as Internet telephony and avoiding packet loss.

On Computational Study of Embodiment: Some Remarks and an Example.

Abstract: Eco-grammar (EG-) systems are proposed as an example of a suitable formal framework for the study of some of the computationally relevant properties of the behavior of collections of embodied agents -- called herds in this article -- sharing a common environment, and acting in it in simple ways.

Design Quality of Security Service Negotiation Protocol

Abstract: With future network equipment the security service becomes a criti- cal and serious problem. Especially in the network, users do not want to expose their message to others or to be forged by others. They make extensive use of cryptography and integrity algorithms to achieve security. The sender can achieve the high quality of security service (high security level), only if the receivers and routers along path to receivers can support or satisfy the quality of security service requested by the sender. Therefore, this paper proposes a protocol to provide the needed mechanism for quality of security service, to dynamically negotiate the qua- lity of security service among the senders and receivers of multicasts in the network. It provides different quality of security service resolutions to different receiver nodes with different security service needs and includes six different negotiation styles.

MVNC: A Multiview Network Computer Architecture

Abstract: In this paper, MVNC, a multiview network computer system for a high usability thin-client computing environment, is introduced. MVNC uses a revised SBC model to offer a new framework for thin client computing. MVNC can be used as a full functional Windows machine, or used as a Linux workstation, or a~graphic terminal. Its multiview work style is achieved by the attempts on GUI seamless integration technology, device integration technology and local video playback support. MVNC is implemented in an embedded Linux environment using a MIPS-4KC microprocessor. Test results on video application show that MVNC system uses its client hardware more efficiently and the load of MVNC server is lightened.