Structural and optical characterization of Ni-doped CdS quantum dots

Ni-doped CdS quantum dots have been prepared by chemical precipitation technique. The X-diffraction results indicated that the particle size of Ni-doped CdS nanoparticles is smaller than that of undoped CdS and no secondary phase was observed. The average grain size of the nanoparticles is found to lie in the range of 2.7–4 nm. The compositional analysis results show that Cd, Ni, and S are present in the samples. HRTEM studies reveal that the average particle size of undoped and Ni-doped CdS quantum dots is 2 and 3 nm, respectively. Raman spectra shows that 1LO, 2LO, and 3LO peaks of the Ni-doped CdS samples are slightly red shifted when compared to that of undoped CdS. The absorption edge of Ni-doped CdS nanoparticles is found to shift towards the higher-wavelength (red shift) side when compared to that of undoped CdS and the band gap is observed to lie in the range of 3.79–3.95 eV. This band gap is higher than that of the bulk CdS and is due to quantum confinement effect present in CdS nanoparticles.     

An efficient fault-tolerant approach for Mobile IP in wireless systems

This paper presents the fault tolerance of Mobile IP in wireless systems. Mobile IP can support wireless users with continuous network connections while changing locations. It is achieved by allocating a number of mobility agents (foreign agents and home agents) in the architecture of a wireless system. If a failure occurs in a mobility agent, the wireless users located in the coverage area of the faulty mobility agent will lose their network connections. To tolerate the failures of mobility agents, this paper proposes an efficient approach to maintaining the network connections of wireless users without being affected by the failures. Once detecting a failure in a mobility agent, failure-free mobility agents are dynamically selected to be organized as a backup set to take over the faulty mobility agent. Compared to the previous approaches, the proposed approach does not take any actions against failures during the failure-free period. Besides, the hardware redundancy technique is also not used in the proposed approach. The overhead of the proposed approach is analyzed using the M/G/c/c queuing model. The results show that the proposed approach can effectively resolve the fault-tolerant problem of Mobile IP in wireless systems.     

Evaluation of enthalpy of sublimation of Zr(tmhd)4 by using thermogravimetric transpiration method

The metallo-organic chemical vapour deposition (MOCVD) of ZrO₂ films is promising in various technological fields. Zr(tmhd)₄, tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)zirconium(IV), has been identified as an ideal precursor. The thermal stability and complete volatility of the synthesized zirconium precursor were inferred from the thermogravimetric analysis. The monomeric structure of the complex was confirmed by electron spray-ionization mass spectroscopy. The vapour pressure measurement was carried out by TG-based transpiration technique and the enthalpy of sublimation was calculated from the slope of Clausius-Clapeyron equation. This yielded a value of 85.36 (± 3.60) kJ mol^− 1 for the standard enthalpy of sublimation over the temperature span of 411-463 K.     

Bessel Gaussian Beam Propagation through Turbulence in Free Space Optical Communication

This paper investigated the experimental demonstration of jitter analysis for Bessel Gaussian beam propagation through the atmospheric turbulence conditions using two different wavelength lasers such as red and green laser. Axicon lens is used to generate Bessel Gaussian beam experimentally and different modulation schemes such as PAM, PPM, PWM, ASK, BPSK and QPSK are used to analyze the phase and time jitter. The Plano-Convex type Axicon is used to create a ring shaped approximation of a Bessel Gaussian beam which increases in diameter over distance while retaining a constant ring thickness. In this BG beam propagation, for red laser the noted phase jitter value is 45.196 radians in ASK and for green laser 36.955 radians in with turbulence conditions. Hence the lower wavelength BG laser beam (green laser) is more energetic than the lower wavelength BG laser beam (red laser).     

Consistency and Completeness in Rough Sets

Consistency and completeness are defined in the context of rough set theory and shown to be related to the lower approximation and upper approximation, respectively. A member of a composed set (union of elementary sets) that is consistent with respect to a concept, surely belongs to the concept. An element that is not a member of a composed set that is complete with respect to a concept, surely does not belong to the concept. A consistent rule and a complete rule are useful in addition to any other rules learnt to describe a concept. When an element satisfies the consistent rule, it surely belongs to the concept, and when it does not satisfy the complete rule, it surely does not belong to the concept. In other cases, the other learnt rules are used. The results in the finite universe are extended to the infinite universe, thus introducing a rough set model for the learning from examples paradigm. The results in this paper have application in knowledge discovery or learning from database environments that are inconsistent, but at the same time demand accurate and definite knowledge. This study of consistency and completeness in rough sets also lays the foundation for related work at the intersection of rough set theory and inductive logic programming.     

Recurrent neural robot controllers: feedback mechanisms for identifying environmental motion dynamics

In this paper a series of recurrent controllers for mobile robots have been developed. The system combines the iterative learning capability of neural controllers and the optimisation ability of particle swarms. In particular, three controllers have been developed: an Exo-sensing, an Ego-sensing and a Composite controller which is the hybrid of the latter two. The task for each controller is to learn to follow a moving target and identify its trajectory using only local information. We show how the learned behaviours of each architecture rely on different sensory representations, although good results are obtained in all cases.