A Power Control MAC Protocol for Ad Hoc Networks

This paper presents a power control MAC protocol that allows nodes to vary transmit power level on a per-packet basis. Several researchers have proposed simple modifications of IEEE 802.11 to incorporate power control. The main idea of these power control schemes is to use different power levels for RTS–CTS and DATA–ACK. Specifically, maximum transmit power is used for RTS–CTS, and the minimum required transmit power is used for DATA–ACK transmissions in order to save energy. However, we show that these schemes can degrade network throughput and can result in higher energy consumption than when using IEEE 802.11 without power control. We propose a power control protocol which does not degrade throughput and yields energy saving.     

Particle Size Effect on the Packaging Performance of YAG:Ce Phosphors in White LEDs

The synthesis of cerium-doped yttrium aluminum garnet (YAG:Ce) phosphor of different sizes with uniform size distribution was carried out using solid-state reaction followed by grinding and sieving method. The effect of particle size distribution of YAG:Ce phosphors on the photoluminescence (PL) properties was investigated. The results demonstrate that the uniform size distribution and particle size affects the packaging performance in white light emitting diode (LED) applications. The YAG:Ce phosphors with different particle sizes were packaged in white LEDs using different amounts of each phosphors in order to get similar efficiency as that of commercially available YAG:Ce phosphors. It was observed that minimum amount of phosphor material is required for smaller particle size for getting the similar efficiency as that exhibited by commercially available YAG:Ce phosphors. The results are particularly interesting in view of reducing the cost of current LEDs by lowering the amount of phosphors without compromising the efficiencies of final LED package. A systematic study of YAG:Ce phosphors on the packing performance in white LEDs is reported.     

Preparation of a Porous Cermet SOFC Anode Substrate by Gelcasting of NiO–YSZ Powders

A porous NiO–YSZ substrate for anode-supported solid oxide fuel cells has been prepared by gelcasting of NiO–YSZ powders using urea–formaldehyde monomers, followed by humidity-controlled drying, binder removal, and sintering of the gelled bodies. The gelled bodies had sufficient strength to remove even 2-mm-thick samples from the mold immediately after gelation. A gelcast NiO–YSZ sample sintered at 1450°C for 2 h showed an open porosity of ∼53 vol%, and the porosity increased to ∼58% upon reduction with hydrogen. Pore sizes measured on the scanning electron microscopy photomicrograph of NiO–YSZ and Ni–YSZ cermet substrates are in the range of 2–5 μm. Urea–formaldehyde polymer, present in a high amount (∼13 wt%) in the gelcast body, acts as a template for pores.     

Exploring the Molecular Interactions of 7,8-Dihydroxyflavone and Its Derivatives with TrkB and VEGFR2 Proteins

7,8-Dihydroxyflavone (7,8-DHF) is a TrkB receptor agonist, and treatment with this flavonoid derivative brings about an enhanced TrkB phosphorylation and promotes downstream cellular signalling. Flavonoids are also known to exert an inhibitory effect on the vascular endothelial growth factor receptor (VEGFR) family of tyrosine kinase receptors. VEGFR2 is one of the important receptors involved in the regulation of vasculogenesis and angiogenesis and has also been implicated to exhibit various neuroprotective roles. Its upregulation and uncontrolled activity is associated with a range of pathological conditions such as age-related macular degeneration and various proliferative disorders. In this study, we investigated molecular interactions of 7,8-DHF and its derivatives with both the TrkB receptor as well as VEGFR2. Using a combination of molecular docking and computational mapping tools involving molecular dynamics approaches we have elucidated additional residues and binding energies involved in 7,8-DHF interactions with the TrkB Ig2 domain and VEGFR2. Our investigations have revealed for the first time that 7,8-DHF has dual biochemical action and its treatment may have divergent effects on the TrkB via its extracellular Ig2 domain and on the VEGFR2 receptor through the intracellular kinase domain. Contrary to its agonistic effects on the TrkB receptor, 7,8-DHF was found to downregulate VEGFR2 phosphorylation both in 661W photoreceptor cells and in retinal tissue.     

Influence of Exposure Time,Shear Stress,and Surfactants on Detachment of <Emphasis Type="Italic">Escherichia coli</Emphasis> O157:H7 from Fresh Lettuce Leaf Surfaces During Washing Process

Washing and sanitation of fresh produce are critical for detachment and inactivation of pathogenic and spoilage microorganisms. The overall goal of this study was to evaluate the influence of processing conditions such as washing time, shear stress, and a food grade surfactant on the detachment of Escherichia coli O157:H7 from lettuce leaf surfaces during a simulated washing process. A benchtop scale rotating disk washing device was designed to simulate the processing conditions used in commercial washing systems. Numerical simulations were carried out to calculate the flow profile and shear stress near the leaf surface. Removal of E. coli O157:H7 as a function of processing conditions in the rotating disk washing device was evaluated by enumeration of bacterial population using plate counting and changes in bioluminescence intensity and further confirmed by bioluminescence imaging. The results showed that shear stress was necessary to remove attached bacteria from inoculated leaf samples and simple incubation of inoculated leaves with wash water was not effective. Furthermore, detachment of bacteria from inoculated leaf samples increased with increasing shear stress and incubation time. Shear stress values in the range of 0 – 300 mPa were adequate to induce removal of approximately 1.5 log CFU/cm² of bacteria from inoculated samples. The addition of a surfactant increased the removal of bacteria from inoculated leaf samples by 0.5 log CFU/cm². Overall, these results may guide the design of new produce wash systems as well as current industrial practice related to flow conditions and use of surfactants during washing of fresh produce.     

Hybrid system for handling premature convergence in GA – Case of grammar induction

Grammar induction (also known as grammar inference or language learning) is the process of learning grammar from training data. This paper presents hybrid genetic algorithm (GA) Tool for handling premature convergence for the case of grammar induction. The tool is developed in Java and the results are tested for the set of 20 languages. It is an effort towards introduction of a hybrid GA system where the collection of more than one type of reproduction methods is used for the grammar induction. Paper also includes the discussion on the various approaches used by author for handling the premature convergence problem in using GA.     

Response Time in Data Broadcast Systems: Mean,Variance and Tradeoff

Data broadcast has been suggested as a promising method of information dissemination [2,33]. In such an environment, the information server cannot afford to serve the requests from a large population of users individually. Instead, the server uses a broadcast channel to deliver information to all users. A single transmission of a data item satisfies all pending requests for that item. The response time of a request depends on the broadcast time of the desired data item, which is scheduled by the server according to the overall demands for various data items. Therefore, the response time may vary in a large range. We argue that, in addition to mean response time, the variance of response time should also be taken into account by the broadcast scheduler. In this paper, we address the issue of variance optimization in regard to response time. Building on our previous research on mean response time optimization, we propose an algorithm which can minimize the variance of response time. Furthermore, we evaluate an algorithm that facilitates a tradeoff between the mean and variance of response time. Numerical examples that illustrate the performance of our algorithms are also presented.     

Hierarchical Delay Test Generation

Delay testing is used to detect timing errors in a digital circuit.In this paper, we report a tool called MODET forautomatic test generation for path delay faults in modular combinational circuits. Our technique usesprecomputed robust delay tests for individual modules to computerobust delay tests for the module-level circuit. We present alongest path theorem at the module level ofabstraction which specifies the requirements for path selectionduring delay testing. Based on this theorem, we propose a pathselection procedure in module-level circuits and report efficientalgorithms for delay test generation. MODET hasbeen tested against a number of hierarchical circuits with impressivespeedups in relation to gate-level test generation.     

Analytical modeling of Junctionless Accumulation Mode Cylindrical Surrounding Gate MOSFET (JAM‐CSG)

This paper presents physics based analytical model for center potential, electric field and subthreshold drain current of Junctionless Accumulation Mode Cylindrical Surrounding Gate MOSFET (JAM‐CSG). The expressions are derived from Poisson's equation in cylindrical co‐ordinate system based on parabolic potential approximation (PPA). The influence of technology parameter variations such as gate length, silicon pillar diameter and oxide thickness on electrical characteristics is studied in detail. Developed analytical model results are validated through the good agreement with simulated data obtained from ATLAS 3D simulator. Copyright © 2016 John Wiley & Sons, Ltd.