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Abstract: When using linear dampers for the suppression of vibration in flexible structures, their mounting locations and the damping coefficients have to be chosen properly. In this article, an approach [...]

This paper presents a new approach of task-oriented developmental learning for humanoid robots. It is capable of setting up multiple tasks representation automatically using real-time experiences, thereby enabling a robot to handle various tasks concurrently without the need of predefining the tasks. In the approach, an evolvable partitioned tree structure is used for task representation knowledgebase that is partitioned into different task domains. The search/update of task knowledge is focused on a particular task branch, without considering the whole task knowledgebase that is often large and time consuming in the process. A prototype of the proposed task-oriented developmental learning is designed and implemented using a Khepera robot. Experimental results show that the robot can redirect itself to new tasks through interactions with the environment, and a learned task can be easily updated in order to meet varying specifications in the real world. Index Terms--Humanoid robots, learning systems, task representation.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2005.03.003 Byline: H.L. Goh, K.K. Tan Abstract: Years have lapsed since the inauguration of the first Wireless Application Protocol (WAP) application. One of the main reasons for the lukewarm response so far may be attributed to the lack of a 'Killer' application. Many companies and developers have attempted to replicate email services (an Internet Killer appplication) within the WAP realm, but till now, no significant success has been reported. This paper will first discuss on the key functions which are lacking in the present WAP-email service, and which are arguably necessary if a much larger user base is to be attracted to these services. A new system will be proposed which can enable the user to send files residing in a remote personal computer (PC) as attachments to his emails using WAP-enabled mobile devices. The implementation of the system will be presented in details. Issue relating to the connection to various types of email servers and the security of the system will also be addressed in the paper. Author Affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore Article History: Received 31 August 2003; Revised 26 February 2005; Accepted 2 March 2005

Zhang et al. presented an excellent neural-network (NN) controller for a class of nonlinear control designs. The singularity issue is completely avoided. Based on a modified Lyapunov function, their lemma illustrates the existence of an ideal control which is important in establishing the NN approximator. In this note, we provide a Lyapunov function to realize an alternative ideal control which is more direct and simpler. The major contributions of this note are divided into two parts. First, it proposes a control scheme which results in a smaller dimensionality of NN than that of Zhang et al. In this way, the proposed NN controller is easier to implement and more reliable for practical purposes. Second, by removing certain restrictions from the design reported by Zhang et al., we further develop a new NN controller, which can be applied to a wider class of systems. Index Terms--Adaptive control, Lyapunov function, neural networks, nonlinear systems.

We develop a decentralized neural-network (NN) controller for a class of large-scale nonlinear systems with the high-order interconnections. The controller is a mixed NN comprised of a conventional NN and a special NN. The conventional NN is used to approximate the unknown nonlinearities in the subsystem, while a special NN is used to counter the high-order interconnections. We prove that this NN structure can achieve a stable controller for the large-scale systems. Index Terms--Decentralized control, large-scale systems, neural networks (NNs), stability.

Following the publication on the principle and theory of a newly proposed non-imaging focusing heliostat, this paper presents a report on the design, optical alignment and application of the first prototype heliostat. In the architecture of the first prototype, 25 mirrors, each with a dimension of 40 x 40 cm, are arranged into five rows and five columns to form a total reflective area of 4 [m.sup.2]. The design of the essential part of the first prototype heliostat will be discussed in this paper, which consists of two primary elements; a rotation-elevation system for tracking a mirror support frame which carries 25 mirror facets, and a separate two-axis tracking system for compensating (each second) off-axis aberrations of 24 slave facets relative to the central mirror, which is fixed in the mirror frame. The rotation-elevation system consists of a pedestal supporting a rotational tracking mechanism carrying a U-shaped arm and a second tracking system for tracking a moving frame in elevation. The moving frame carries a central stationary (relative to the frame) mirror, called a master mirror. Slave mirrors are arrayed in five rows and five columns, and eight stepper motors drive the outer four rows and columns relative to the master mirror via a computer programme implementing newly proposed formulas to eliminate the first-order aberration. With a second stage concentrator comprising a small aperture size parabolic mirror (diameter of 60 cm), a cost-effective high temperature solar furnace was constructed. In our experiment, the highest furnace temperature of 3400[degrees]C has been recorded through the melting of pure tungsten wires.

This paper describes a robust adaptive compensation method for friction and force ripple present in the dynamics of permanent-magnet linear motors. The method is used in ultraprecise positioning applications. The compensation algorithm consists of a PID component and an adaptive component for estimating friction and force ripple. The adaptive component is continuously refined on the basis of just prevailing input and output signals. Computer simulations and real-time experimental results verify the effectiveness of the proposed scheme for high-precision motion trajectory tracking. Index Terms--Cogging force, friction, permanent magnet linear motor, ripple force.

The dengue virus type 3 (DENV-3) homotypic outbreak cycles reported in Klang Valley, Malaysia in 1992–1995 and 2002 demonstrated different epidemic magnitude and duration. These outbreak cycles were caused by two closely related strains of viruses within the DENV-3 genotype II (DENV-3/II). The role of viral genotypic diversity and factors that could have influenced this phenomenon were investigated. The serum neutralisation sensitivity of DEN3/II strains responsible for the DENV-3 outbreak cycles in 1992–1995 and 2002 were examined. Representative virus isolates from the respective outbreaks were subjected to virus neutralisation assay using identified sera of patients with homotypic (DENV-3) or heterotypic dengue infections (DENV-1 and DENV-2). Results from the study suggested that isolates representing DENV-3/II group E (DENV-3/II-E) from the 1992–1995 outbreak and DENV-3/II group F (DENV-3/II-F) from the 2002 outbreak were neutralised at similar capacity (intergenotypic differences <2-fold) by sera of patients infected with DENV-3, DENV-1 and DENV-2/Asian genotypes. Sera of the DENV-2/Cosmopolitan infection efficiently neutralised DENV-3/II-F (FRNT50 = 508.0) at a similar neutralisation capacity against its own homotypic serotype, DENV-2 (FRNT50 = 452.5), but not against DENV-3/II-E (FRNT50 = 100.8). The different neutralisation sensitivities of DENV-3/II strains towards the cross-reacting DENV-2 heterotypic immunity could play a role in shaping the DENV-3 recurring outbreaks pattern in Malaysia. Two genetic variations, E-132 (H/Y) and E-479 (A/V) were identified on the envelope protein of DENV-3/II-E and DENV-3/II-F, respectively. The E-132 variation was predicted to affect the protein stability. A more extensive study, however, on the implication of the naturally occurring genetic variations within closely related DENV genotypes on the neutralisation profile and protective immunity would be needed for a better understanding of the DENV spread pattern in a hyperendemic setting. [ABSTRACT FROM AUTHOR]