A low-power high-performance SiGe BiCMOS 802.11a/b/g transceiver IC for cellular and bluetooth Co-existence applications

This paper describes a high-performance WLAN 802.11a/b/g radio transceiver, optimized for low-power in mobile applications, and for co-existence with cellular and Bluetooth systems in the same terminal. The direct-conversion transceiver architecture is optimized in each mode for low-power operation without compromising the challenging RF performance targets. A key transceiver requirement is a sensitivity of -77 dBm (at the LNA input) in 54 Mb/s OFDM mode while in the presence of a GSM1900 transmitter interferer. The receiver chain achieves an overall noise figure of 2.8/3.2 dB, consuming 168/185 mW at 2.8 V for the 2.4/5GHz bands, respectively. Signal loopback and transmit power detection techniques are used in conjunction with the baseband modem processor to calibrate the transmitter LO leakage and the transceiver I/Q imbalances. Fabricated in a 70 GHz f/sub T/ 0.25-/spl mu/m SiGe BiCMOS technology for system-in-package (SiP) use, the dual-band, tri-mode transceiver occupies only 4.6 mm/sup 2/.     

A joint parametric prediction model for wireless internet traffic using Hidden Markov Model

Addressing performance related issues of networks and ensuring better Quality of Service (QoS) for end-users calls for simple, tractable and realistic traffic models. The work reported here focuses on modelling the Wireless Internet traffic using realistic traffic traces collected over wireless networks and forecasting the end-to-end QoS parameters for the networks. A measurement framework is set-up to collect the QoS parameters and a traffic model is designed based on Hidden Markov Model considering joint distribution of End to End Delay (E2ED or d), Inter-Packet Delay Variation (IPDV) and Packet Size. States are mapped to the four traffic classes namely conversational, streaming, interactive, and background. The model is validated by forecasting QoS parameters and the results are shown to be within the tolerance limit.     

New voltage and current-mode APS using current controlled conveyor

A first-order all-pass section (APS) is introduced employing a single second-generation current conveyor and three passive components. The translinear conveyor version of the circuit employing only two passive components is also proposed. A fully tunable version of the circuit employing two current controlled conveyors (CCCIIs) and a single capacitor is finally derived. All the three versions of APS can be operated both in voltage as well as current mode without changing the circuit configuration. As an application, a quadrature oscillator providing two quadrature currents and two phase-shifted voltage outputs simultaneously, is realized using the proposed APS. RSPICE simulation results for the translinear-C APS, and the translinear-C quadrature oscillator are included to verify the theory.     

Data Congestion Control Using Offloading in IoT Network

Internet of Things (IoT) is being used by a large number of applications and transmitting huge amounts of data. IPv6 routing protocol for low power and lossy networks (RPL) is being standardized for routing in IoT networks. However, it is difficult to handle such huge transmission as it is initially designed for Low power and lossy networks. In this paper, we present the mechanism for the reduction of overhead from the congested parent node by offloading its partial load. For offloading the packet, a suitable neighbor is selected based on its status of energy, buffer, link quality, number of child nodes, and distance. This approach focuses on the enhancement of RPL by including the mechanism for congestion control. The approach reduces the delay and packet loss rate while avoiding congestion in a suitable manner. The proposed approach is beneficial in terms of throughput and packet receiving ratio as compared to the comparative approaches.

     

A Comprehensive Neural Network Model for Colorization and Captioning of Images Along with IoT Deployment

The convergence of artificial neural networks and the internet of things (IoT) has gained popularity in the field of computer science research. In this work, an efficient neural network model for the image colorization problem is proposed along with deploying these models to the remote system using IoT deployment tools. Further, this work proposed two convolution neural network models namely the Alpha model and Beta model towards solving the image colorization of the grayscale format. An efficient combination of models is proposed and analyzed such that the loss rate is minimized as?~?0.005. Next, an efficient model for solving image captioning is proposed based on the bi-directional long short term memory model. Finally, the work discusses the merits and demerits of deploying the neural network model using the AWS Greengrass and Docker IoT environment on remote systems.

     

MHD Flow Through Porous Medium in Presence of Heat and Mass Transfer With Heat Source

Unsteady free convection and mass transfer flow past an accelerated infinite nonconducting vertical plate through a porous medium have been analyzed in the presence of a uniform magnetic field and constant heat source. Expressions for the velocity field for two different cases are obtained by the Laplace-transform technique. The influence of the various parameters entering into the problem on the velocity field is extensively discussed.     

Effect of conspecific and heterospecific feces on foraging and oviposition of two predatory ladybirds: role of fecal cues in predator avoidance

Growing evidence suggests a flow of chemical information from higher to lower trophic levels that affects foraging and oviposition of prey in response to potential risks from predators. This was investigated in two species of ladybird predators of aphids, Harmonia axyridis and Propylea japonica. H. axyridis is known to be the stronger intraguild predator and P. japonica to be the more frequent intraguild prey in interactions of these two species. These ladybirds share aphid prey on mugworts, hibiscus, and Italian ryegrasses in fields of northern Japan but largely avoid each other on the same plant. Fecal cues of these ladybird predators were found to contribute in their assessment of predation risk from conspecific and heterospecific competitors in common habitats. Gravid females of H. axyridis reduced rates of feeding and oviposition when exposed to feces of conspecifics, but not when exposed to feces of P. japonica. In contrast, gravid females of P. japonica reduced feeding and oviposition when exposed to feces of both H. axyridis and its own species. Females of both ladybird species exhibited similar behavior in response to water extracts of feces. For P. japonica, the influence of heterospecific feces was greater than that of conspecific feces. Our results demonstrate that feces of ladybirds contain odors that have the potential to deter the feeding and oviposition activities of conspecific as well as heterospecific ladybirds. Such deterrence allows these insects to avoid predation risk. Differences in responses of the two predators are discussed.     

THERMOCHEMICAL CONVERSION OF BIOMASS TO CHARCOAL: COLLECTION AND CHARACTERIZATION OF BYPRODUCT

Thermochemical conversion of biomass was carried out using a laboratory pyrolyzer at temperatures of 280-500°C. The charcoal yield varied from 72 and 40% respectively and the tar yield at the above two temperatures varied from 2.0 and 4.2%. The structure of charcoal and bio-oil was determined by infrared and nuclear magnetic resonance. The non-condensible gases were analyzed by gas chromatography.