Efficient electrochemomechanical energy conversion in nanochannels grafted with polyelectrolyte layers with pH-dependent charge density

Nanochannels, functionalized by grafting with a layer of charged polyelectrolyte (PE), have been employed for a large number of applications such as flow control, ion sensing, ion manipulation, current rectification and nanoionic diode fabrication. Recently, we established that such PE-grafted nanochannels, often denoted as “soft” nanochannels, can be employed for highly efficient, streaming-current-induced electrochemomechanical energy conversion in the presence of a background pressure-driven transport. In this paper, we extend our calculation for the practically realizable situation when the PE layer demonstrates a pH-dependent charge density. Consideration of such pH dependence necessitates consideration of hydrogen and hydroxyl ions in the electric double layer charge distribution, cubic distribution of the monomer profile, and a PE layer-induced drag force that accounts for this given distribution of the monomer profile. Our results express a hitherto unknown dependence of the streaming electric field (or the streaming potential) and the efficiency of the resultant energy conversion on parameters such as the pH of the surrounding electrolyte and the \(\hbox {pK}_{\mathrm{a}}\) of the ionizable group that ionizes to produce the PE charge—we demonstrate that increase in the pH and the PE layer thickness and decrease in the \(\hbox {pK}_{\mathrm{a}}\) and the ion concentration substantially enhance the energy conversion efficiency.     

Hadamard quantum broadcast channels

We consider three different communication tasks for quantum broadcast channels, and we determine the capacity region of a Hadamard broadcast channel for these various tasks. We define a Hadamard broadcast channel to be such that the channel from the sender to one of the receivers is entanglement-breaking and the channel from the sender to the other receiver is complementary to this one. As such, this channel is a quantum generalization of a degraded broadcast channel, which is well known in classical information theory. The first communication task we consider is classical communication to both receivers, the second is quantum communication to the stronger receiver and classical communication to other, and the third is entanglement-assisted classical communication to the stronger receiver and unassisted classical communication to the other. The structure of a Hadamard broadcast channel plays a critical role in our analysis: The channel to the weaker receiver can be simulated by performing a measurement channel on the stronger receiver’s system, followed by a preparation channel. As such, we can incorporate the classical output of the measurement channel as an auxiliary variable and solve all three of the above capacities for Hadamard broadcast channels, in this way avoiding known difficulties associated with quantum auxiliary variables.     

Landcover classification in MRF context using Dempster-Shafer fusion for multisensor imagery.

This work deals with multisensor data fusion to obtain landcover classification. The role of feature-level fusion using the Dempster-Shafer rule and that of data-level fusion in the MRF context is studied in this paper to obtain an optimally segmented image. Subsequently, segments are validated and classification accuracy for the test data is evaluated. Two examples of data fusion of optical images and a synthetic aperture radar image are presented, each set having been acquired on different dates. Classification accuracies of the technique proposed are compared with those of some recent techniques in literature for the same image data.     

A Novel Heterogeneous Clustering Protocol for Lifetime Maximization of Wireless Sensor Network

The network lifetime of Wireless Sensor Network (WSN) is one of the most challenging issues for any network protocol. The nodes in the network are densely deployed and are provided with limited power supply. The routing strategy is treated as an effective solution to improve the lifetime of the network. The cluster based routing techniques are used in the WSN to enhance the network lifespan and to minimize the energy consumption of the network. In this paper, an energy efficient heterogeneous clustering protocol for the enhancement of the network lifetime is proposed. The proposed protocol uses the sensor energy for the clustering process in a well-organized manner to maximize the lifetime of network. The MATLAB simulator is used for implementing the clustering model of proposed protocol and for measuring the effectiveness of the proposed technique the comparison is performed with the various existing approaches such as Stability Election Protocol, Distributed Energy Efficient Clustering and Adaptive Threshold Energy Efficient cross layer based Routing.

     

A dynamic threshold based approach for mitigating black-hole attack in MANET

Mobile ad-hoc network is an infrastructure less type of network which does not require any kind of fixed infrastructure. It provides multi-hop communication between the source and destination nodes which are not within the direct range of each other through the intermediate nodes. These intermediate nodes cooperate with other nodes in finding an optimum and shortest route toward the destination. However, in holistic environments, some nodes do not cooperate with other nodes in finding the optimal route towards the destination and intentionally give the false route information of having the shortest path toward the destination with a high destination sequence number in order to attract the traffic toward itself and start dropping of the data packets instead of forwarding it. This type of routing misbehaviour is generally called as black hole attack or full packet dropping attack which is one of the most severe destructive attacks that lead to the network degradation. In this paper, we have proposed a protocol called as Mitigating Black Hole effects through Detection and Prevention (MBDP-AODV) based on a dynamic threshold value of the destination sequence number. In order to validate the efficiency of proposed protocol, the NS-2.35 simulator is used. The simulation results show that proposed protocol performs better as compared with existing one under black hole attack.     

Light Amplification and Efficient Electroluminescence from a Solution-Processable Diketopyrrolopyrrole Derivative via Triplet-to-Singlet Upconversion

Over the years, achieving efficient electroluminescence (EL) while simultaneously having low light amplification thresholds under optical excitation has been the key to progression toward the long-thought objective of electrically pumped organic lasers. While significant progress in this regard has been made for organic semiconductors emitting in the blue–green region of the visible spectrum, organic laser dyes with low-energy emission (>600 nm) still suffer from high amplified spontaneous emission (ASE) thresholds and low external quantum efficiencies (EQEs) in devices. Herein, low ASE thresholds and efficient EL are reported from a solution-processable organic laser dye dithiophenyl diketopyrrolopyrrole (DT-DPP). The ASE threshold of 4 µJ cm⁻² at the wavelength of 620 nm is obtained while making constructive use of triplet excitons by doping DT-DPP in a green-emitting host matrix, which exhibits thermally activated delayed fluorescence (TADF). The organic light-emitting diode fabricated from this system gives a high EQE of 7.9% due to the efficient utilization of triplet excitons. Transient EL studies further show that a high reverse intersystem crossing rate is crucial in achieving lasing under electrical pumping from such TADF-assisted fluorescent systems.     

A dynamic threshold based algorithm for improving security and performance of AODV under black-hole attack in MANET

Wireless Networks - Mobile Ad hoc network (MANET) is a wireless network which is characterized by dynamic network topology, open medium, multi-hop communication etc. in which each device not only...     

KINETICS OF CORN COB CHAR GASIFICATION IN CARBON DIOXIDE

The Reactivity of corn cob char in CO₂ has been studied on a thermogravimetric balance to develop a rate equation for the design of biomass gasifiers operating on corn cob char. Experiments in the range of 650-1000^°C were conducted with cylindrical shaped pellets of 1 cm diameter having L/D=l. The average porosity of the pellets was 0.5. It was observed that the rate of the CO₂/char reaction decreased with increase in temperature from 650-750^°C and then increased with temperature upto 1000^°C.

The data obtained at temperatures 750^°C and above has been used to determine a rate equation for char gasification. It has been found that the reaction proceeds according to the Sharp Interface Model (SIM) with a first order chemical reaction as the rate controlling step. The activation energy is found to be 40 Kcal/mole with frequency factor being 1.2 × 10⁷ mm/sec. Analysis of the data obtained for the decreasing reaction rate regime (650-750^°C) indicates that the change in the ash structure result in this kind of behavior.     

Optimal heat extraction from an updraft biomass reactor

This paper presents the design of gas-water and gas-air heat exchangers for extraction of thermal energy from updraft biomass gasifiers in the firing rate range 10–120 kg/h. Mathematical models are developed to study the sensitivity of the heat exchanger efficiency and effectiveness to geometric and flow variables. Optimal parameters to suit the biomass reactor have been evolved. The calculated heat transfer coefficients have been compared with experimental results obtained in test gas-water and gas-air heat exchangers with an observed deviation between −25 and + 17%. In conclusion, system efficiencies of about 75–80% can be achieved by choice of appropriate operating flow regimes and heat exchanger sizes.     

Mössbauer Study of the Influence of Fe-Si-N Liquid in the Synthesis of β-Si3N4 from Silica

Mössbauer spectra of the products obtained by carbothermal reduction and distribution of silica in the presence of iron in the temperatures range 1200^o to 1540^o were studied. The preponderance of β- Si₃N₄ over the α form at a higher reaction temperature were assumed to be related to the formation of an Fe-Si-N liquid. The liquid did not alter its composition with the variation of reduction-temprature, Iron had no effect on the reaction mechanism below 1300^oC.