Sparseness-controlled adaptive algorithms for supervised and unsupervised system identification

In single-channel hands-free telephony, the acoustic coupling between the loudspeaker and the microphone can be strong and this generates echoes that can degrade user experience. Therefore, effective acoustic echo cancellation (AEC) is necessary to maintain a stable system and hence improve the perceived voice quality of a call. Traditionally, adaptive filters have been deployed in acoustic echo cancellers to estimate the acoustic impulse responses (AIRs) using adaptive algorithms. The performances of a range of well-known algorithms are studied in the context of both AEC and network echo cancellation (NEC). It presents insights into their tracking performances under both time-invariant and time-varying system conditions. In the context of AEC, the level of sparseness in AIRs can vary greatly in a mobile environment. When the response is strongly sparse, convergence of conventional approaches is poor. Drawing on techniques originally developed for NEC, a class of time-domain and a frequency-domain AEC algorithms are proposed that can not only work well in both sparse and dispersive circumstances, but also adapt dynamically to the level of sparseness using a new sparseness-controlled approach. As it will be shown later that the early part of the acoustic echo path is sparse while the late reverberant part of the acoustic path is dispersive, a novel approach to an adaptive filter structure that consists of two time-domain partition blocks is proposed such that different adaptive algorithms can be used for each part. By properly controlling the mixing parameter for the partitioned blocks separately, where the block lengths are controlled adaptively, the proposed partitioned block algorithm works well in both sparse and dispersive time-varying circumstances. A new insight into an analysis on the tracking performance of improved proportionate NLMS (IPNLMS) is presented by deriving the expression for the mean-square error. By employing the framework for both sparse and dispersive time-varying echo paths, this work validates the analytic results in practical simulations for AEC. The time-domain second-order statistic based blind SIMO identification algorithms, which exploit the cross relation method, are investigated and then a technique with proportionate step-size control for both sparse and dispersive system identification is also developed

From Half-metal to Semiconductor: Electron-correlation Effects in Zigzag SiC Nanoribbons From First Principles

We performed electronic structure calculations based on the first-principles many-body theory approach in order to study quasiparticle band gaps, and optical absorption spectra of hydrogen-passivated zigzag SiC nanoribbons. Self-energy corrections are included using the GW approximation, and excitonic effects are included using the Bethe-Salpeter equation. We have systematically studied nanoribbons that have widths between 0.6 $\text{nm}$ and 2.2 $\text{nm}$. Quasiparticle corrections widened the Kohn-Sham band gaps because of enhanced interaction effects, caused by reduced dimensionality. Zigzag SiC nanoribbons with widths larger than 1 nm, exhibit half-metallicity at the mean-field level. The self-energy corrections increased band gaps substantially, thereby transforming the half-metallic zigzag SiC nanoribbons, to narrow gap spin-polarized semiconductors. Optical absorption spectra of these nanoribbons get dramatically modified upon inclusion of electron-hole interactions, and the narrowest ribbon exhibits strongly bound excitons, with binding energy of 2.1 eV. Thus, the narrowest zigzag SiC nanoribbon has the potential to be used in optoelectronic devices operating in the IR region of the spectrum, while the broader ones, exhibiting spin polarization, can be utilized in spintronic applications.Comment: 22 pages, 6 figures (included

Fire fighting robot

Fire-fighting is an important but dangerous occupation. A fire-fighter must be able to put out fire quickly and safely. This is a common way to prevent fatalities and further damages. So, technology has done its part by bridging up the gap between fire fighters and machineries. So, a robot is invented in order to combine both man kind and technology [1]. Fire Fighting Robot is designed to put out a fire, before it reaches out of control. Robot with these fire-handling abilities is a great advantage to replace fire extinguishers [2]. Water-based robot will be an advantage for users to refill the tank as it goes empty. Users can fill up water and keep the robot in a safe position. Water is a basic non-chemical liquid which will not experience any expiry or damage or corrosion. This invention would be a great contribution to mankind in order to ease their work and minimize the risk during fire put out

TamilTB: An Effort Towards Building a Dependency Treebank for Tamil

Annotated corpora such as treebanks are important for the development of parsers, language applications as well as understanding of the language itself. Only very few languages possess these scarce resources. In this paper, we describe our effort in syntactically annotating a small corpora (600 sentences) of Tamil language. Our annotation is similar to Prague Dependency Treebank (PDT 2.0) and consists of 2 levels or layers: (i) morphological layer (m-layer) and (ii) analytical layer (a-layer). For both the layers, we introduce annotation schemes i.e. positional tagging for m-layer and dependency relations (and how dependency structures should be drawn) for a-layers. Finally, we evaluate our corpora in the tagging and parsing task using well known taggers and parsers and discuss some general issues in annotation for Tamil language

Habitat and Morphological Characteristics of Halophila Ovalis in Malaysia

An assessment on habitat, environment and morphological characteristics of Halophila ovalis are described for the 11 locations. Halophila ovalis grew in variable habitats encompassing inter-tidal degraded coral reef platform (Teluk Kemang), sub-tidal shoal (Merambong, Tanjung Adang Laut, Tanjung Adang Darat of Johore), off-shore island (Pulau Tinggi), Inter-tidal lagoon (Merchang), sub-tidal degraded coral reef (Pulau Gaya, Pulau Bakkungan, Pulau Selingan of Sabah), sub-tidal estuary (Teluk Sepinong of Sabah) and inter-tidal beach front (Punang of Sarawak). Amongst these habitats, Merambong was visited at regular basis to obtain habitat characteristics and environmental factors. Halophila ovalis are found occurring at the depth ranging from 1.0 to 2.7 m MSL in shallow water. They grew on substrate; sand covered coral e.g. Teluk Kemang, calcareous muddy sand e.g. Merambong, Tanjung Adang Laut, Tanjung Adang Darat, fine sand e.g. Pulau Tinggi, muddy sand e.g. Merchang, Punang, corraline sand e.g Pulau Gaya, Pulau Bakkungan, Pulau Selingan, An assessment on habitat, environment and morphological characteristics of Halophila ovalis are described for the 11 locations. Halophila ovalis grew in variable habitats encompassing inter-tidal degraded coral reef platform (Teluk Kemang), sub-tidal shoal (Merambong, Tanjung Adang Laut, Tanjung Adang Darat of Johore), off-shore island (Pulau Tinggi), Inter-tidal lagoon (Merchang), sub-tidal degraded coral reef (Pulau Gaya, Pulau Bakkungan, Pulau Selingan of Sabah), sub-tidal estuary (Teluk Sepinong of Sabah) and inter-tidal beach front (Punang of Sarawak). Amongst these habitats, Merambong was visited at regular basis to obtain habitat characteristics and environmental factors. Halophila ovalis are found occurring at the depth ranging from 1.0 to 2.7 m MSL in shallow water. They grew on substrate; sand covered coral e.g. Teluk Kemang, calcareous muddy sand e.g. Merambong, Tanjung Adang Laut, Tanjung Adang Darat, fine sand e.g. Pulau Tinggi, muddy sand e.g. Merchang, Punang, corraline sand e.g Pulau Gaya, Pulau Bakkungan, Pulau Selingan, seagrass such as H. ovalis. Cultured H. ovalis from different locations also showed variation in morphology. Halophila ovalis has a wide range of variability in vegetative structure dimensions particularly the shapes of leaves and paired of cross veins counts and this variability explains their ecological adaptation to different habitats and environmental conditions

Profitability of fertilising young coconut. results of three long-term field experiments

Two long term field experiments on newly cleared lands carried out in the intermediate rainfall zone of Sri Lanka showed that profits of the order of Rs. 3560 to 7120/ha/yr could be obtained during the initial bearing period from systematic NPK fertilizer application to young palm. Total income from the fertilized palms during carried out on underpalned young palms in the same rainfall zone are Rs. 315 to 3950/ha/yr and Rs. 1580 to 7900/ha/yr respectively. Breakeven point of net present value of investment in the early years and the returns fall on the 6th and 9th year in the new plantation and 15 th year in the underplanted land. To the underplanted experiment, palms which had not recieved fertilizers for the initials 17 years, had notrecovered, even after continued fertilization subsequently for 10 years