Partial permutation decoding for the first-order Reed-Muller codes

Partial permutation decoding is shown to apply to the first-order Reed-Muller codes R(1,m), where m>4 by finding s-PD-sets for these codes for 2≤s≤4.     

1/f Noise in dye-sensitized solar cells and NIR photon detectors

All electronic devices are plagued with 1/f noise originating from many causes. The most important factors contributing to 1/f noise in a semiconductor is believed to be recombination of carriers and their trapping at defects and impurity sites. Adsorption of moisture and electron acceptor molecules enhances the intensity of 1/f noise. Amazingly, some molecular species that strongly chelate to the semiconductor surface, suppress 1/f noise owing to passivation of the recombination sites. Thus in addition to sensitization, the dye adsorbed on the nanocrystallites plays a key role in mitigation of recombinations. For this reason dye-sensitized heterojunctions could also find application as low noise NIR photon detectors. Experiments conducted with oxide semiconductors (TiO₂, ZnO, SnO₂) indicate that the mode of binding of dyes at specific sites determines the extent to which the recombination and 1/f noise are suppressed. The transport of electrons in a nanocrystalline matrix is diffusive with a diffusion coefficient D depending on the trapping and detrapping processes. Thus passivation of trapping sites by the adsorbed dye is expected to increase the response time which can be expressed as τ  L²/D, where L = thickness of the nanocrystalline film. Measurement techniques and construction of a dye-sensitized NIR photon detector will be discussed.     

Thermodynamic assessment of Hg(II)-gibbsite interactions

As discrete particles and/or as surface coatings on other minerals in natural systems, aluminum hydroxides are efficient sinks for Hg(II). The Hg(II) adsorption on gibbsite was determined as a function of temperature (T), pH, and the type of background electrolytes, i.e., NaNO(3), NaClO(4), and NaCl. When the equilibration time t(E) approximately 2 h, the Hg(II) retention on gibbsite was found to be a reversible process, which was ascribed to adsorption. The Hg(II) adsorption capacity, i.e., Gamma(Hg(II)), varied with the type of electrolyte used in accordance with the following order: Gamma(NO(3))(Hg(II)) > or = Gamma(ClO(4))(Hg(II)) > or = Gamma(Cl)(Hg(II)). In all cases, the estimated thermodynamic parameters showed that the Hg(II) adsorption on gibbsite was endothermic and spontaneous. The Hg(II) adsorption data were quantified with the Langmuir or Hill, and Dublin-Radushkevick (DR), isotherms at all temperatures and acidity levels examined. Always, the Hg(II) adsorption data were in compliance with the DR model. However, the Hg(II) adsorption in NaNO(3) or NaClO(4) was interpreted in terms of the Langmuir model. When NaCl was used as electrolyte, the Hg(II) adsorption was modeled well with the Hill equation. The mean free energy values calculated from DR plots concluded that Hg(II)-gibbsite interactions are a result of chemical bonding.     

Modelling of closed-chain manipulators on an excavator vehicle

The main focus of this paper is to develop a physics-based model for a closed-chain manipulator in an excavator vehicle. The derivation of closed-chain manipulator dynamic equations with a structure similar to open-chain manipulator equations is an important research problem, particularly with reference to controller design. In this paper, an approach for deriving closed-chain manipulator equations with an open-chain structure, based on trigonometric t-formulae, is presented. Holonomic loop closure constraints are employed in order to derive the closed-chain mechanism dynamics from the reduced system dynamics. The closed-chain equations, with a structure similar to serial link equations, are presented. The model incorporates the dynamic properties of the manipulator and bucket. The dynamic model for the excavation system is validated against measured data obtained from a full-scale closed-chain excavator vehicle. A dynamic model is important for the design of control strategies for trajectory tracking, a key requirement for automating the excavation task. It is noted that even though the results presented in this paper are focused on a particular excavator vehicle, the research is generic and can be adapted to any closed-chain manipulator.     

Establishment of a quality system at the Nuclear Analytical Laboratories of the Atomic Energy Authority, Sri Lanka

A quality system according to the requirements of ISO/IEC guidelines has been introduced at the Nuclear Analytical Laboratories of the Atomic Energy Authority, which has received appreciation from International Atomic Energy Agency (IAEA) inspection evaluation reports (RAS/2/010) showing a positive indication to accreditation. The quality system has achieved the “analytical quality” through technical competence by non-conformance management. The experience in the progression towards achieving a quality system is described with examples from zero level to a positive index. This nuclear analytical service laboratory shows long-term stability of performance and enhances its credibility to customers, through the quality system.     

Permutation decoding for binary codes from lattice graphs

By finding explicit PD sets, we show that permutation decoding can be used for the binary code obtained from the row span over the field F₂ of an adjacency matrix of the lattice graph L₂(n) for any n?5.