Integrated Context-Based Mitigation Framework for Enforcing Security against Rendezvous Point Attack in MANETs

Wireless Personal Communications - Reliable communication in ad hoc networks necessitates mobile nodes to synchronize among themselves for cooperation. The cooperation in ad hoc networks...     

L-shaped piezoelectric motor--part I: design and experimental analysis

This paper proposes an L-shaped piezoelectric motor consisting of two piezoelectric bimorphs of different lengths arranged perpendicularly to each other. The coupling of the bending vibration mode of the bimorphs results in an elliptical motion at the tip. A detailed finite element model was developed to optimize the dimensions of bimorph to achieve an effective coupling at the resonance frequency of 246 Hz. The motor was characterized by developing rotational and linear stages. The linear stage was tested with different friction contact surfaces and the maximum velocity was measured to be 12 mm/s. The rotational stage was used to obtain additional performance characteristics from the motor: maximum velocity of 120 rad/s, mechanical torque of 4.7 × 10-(5) N·m, and efficiency of 8.55%.     

Cross Layer QoS Guaranteed Fault Tolerance for Data Transmission in Mobile Wireless Sensor Networks

Wireless Personal Communications - Wireless sensor network comprises several small nodes distributed randomly in an area under observation. These nodes sense the assigned physical phenomenon...     

Study of Read Recovery Dynamic Faults in 6T SRAMS and Method to Improve Test Time

Capturing dynamic and hard to detect faults in static embedded memories is a significant challenge for DFT designers. Not only it demands at-speed testing, it also requires a large number of operations (generally greater than 24 consecutive reads per memcell) on each memory cell, which is hard to achieve at lower testing budgets. We present a comprehensive study done on resistive defects which lead to read recovery faults in 6T memcell SRAMs. A novel DFT technique has been proposed using calibrated variation in dummy path of self timed memories to capture hard to detect resistive faults in small number of operations. Results show 89% reduction in test time for a robust test on an industrial SRAM with 2048 words operating at 400 MHz.     

Photocatalytic degradation of aqueous propoxur solution using TiO2 and Hbeta zeolite-supported TiO2

Photocatalytic activity of TiO2 and zeolites supported TiO2 were investigated using propoxur as a model pollutant. Hbeta, HY and H-ZSM-5 zeolites were examined as supports for TiO2. Hbeta was chosen as the TiO2 support based on the adsorption capacity of propoxur on these zeolites (Hbeta>HY=H-ZSM-5). TiO2/Hbeta photocatalysts with different wt.% were prepared and characterized by XRD, FT-IR and BET surface area. The progress of photocatalytic degradation of aqueous propoxur solution using TiO2 (Degussa P-25) and TiO2 supported on Hbeta zeolite was monitored using TOC analyzer, HPLC and UV-vis spectrophotometer. The degradation of propoxur was systematically studied by varying the experimental parameters in order to achieve maximum degradation efficiency. The initial rate of degradation with TiO2/Hbeta was higher than with bare TiO2. TOC results revealed that TiO2 requires 600min for complete mineralization of propoxur whereas TiO2/Hbeta requires only 480min. TiO2/Hbeta showed enhanced photodegradation due to its high adsorption capacity on which the pollutant molecules are pooled closely and hence degraded effectively.     

Correction to Mayrath et al. (2011).

Reports an error in Varying tutorial modality and interface restriction to maximize transfer in a complex simulation environment by Michael C. Mayrath, Priya K. Nihalani and Daniel H. Robinson (Journal of Educational Psychology, , , np). The name of the author Laura G. Torres was omitted. (The following abstract of the original article appeared in record 2011-01107-001.) In 2 experiments, 241 undergraduates with low domain knowledge viewed a tutorial on how to use Packet Tracer (PT), a computer-networking training simulation developed by the Cisco Networking Academy. Participants were then tested on retention of tutorial content and transfer using PT. Tutorial modality (text, narration, or narration plus text) was varied betweens subjects in both experiments, and simulation interface restriction (restricted or unrestricted) was varied between subjects only in Experiment 1. When PT's interface was unrestricted, students who received the narration tutorial performed better on the transfer task compared with students who received the text tutorial (statistically significant in Experiment 1 but not in Experiment 2). These findings extend the cognitive theory of multimedia learning (Mayer, 2005) by testing modality effects in new contexts and further specifying conditions of its applicability. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A mechanistic study of hydrogenation of coal. 2.

In Part 1 the authors reported that liquefaction of coal by hydrogenation in the presence or absence of vehicle and with or without catalyst progresses with characteristic variations of the reaction order. In the present paper, the roles of temperature, hydrogen, vehicle and catalyst have been studied using a free-radical scavenger such as p-benzoquinone or iodine. Based on these results, a set of characteristic reactions has been identified from which the following overall rate equation has been derived: $\text{d[P}{}_{\mathrm{m}}\text{]}\text{dt}\text{= β}{}_1\text{[C] + β}{}_2\text{[C]}{}^2\text{+ β}{}_3$ where [P_m] denotes gas, and benzene-soluble products, [C] represents the percentages of organic matter in coal and benzene insoluble intermediates, and β₁, β₂ and β₃ are constants. The rate equation thus explains the experimentally observed variation of the reaction order, which depends on the predominance of a particular group of reactions. It has been postulated that pyrolysis is the main driving force, and that hydrogenation of coal either with gaseous hydrogen or by hydrogen-donating vehicle is basically influenced by reactions involving free radicals.     

Design and fabrication of bimorph transducer for optimal vibration energy harvesting

High energy density piezoelectric composition corresponding to 0.9Pb(Zr0.56Ti0.44)O3–0.1Pb[(Zn0.8/3Ni0.2/3) Nb2/3]O3 + 2 mol% MnO2 (PZTZNN) and 0.8[Pb(Zr0.52Ti0.48) O3]-0.2[Pb(Zn1/3Nb2/3)O3] (PZTPZN) were synthesized by conventional ceramic processing technique using three different sintering profiles. Plates of the sintered samples were used to fabricate the piezoelectric bimorphs with optimized dimensions to exhibit resonance in the loaded condition in the range of ~200 Hz. An analytical model for energy harvesting from bimorph transducer was developed which was confirmed by experimental measurements. The results of this study clearly show that power density of bimorph transducer can be enhanced by increasing the magnitude of product (d ? g), where d is the piezoelectric strain constant and g is the piezoelectric voltage constant.     

Activities and immiscibility in the system Cu-Rh

The thermodynamic activity of rhodium in solid Cu-Rh alloys is measured by the electromotive force method in the temperature range from 1050 to 1325 K with a solid-state cell:

Understanding texture domains and relations between pre-eutectic and eutectic phase during Al-Si alloy solidification

Phase morphology and crystallographic texture are important components of a solidification microstructure. Probability of nucleation of a nucleus is a strong function of local chemical & thermal conditions and its atomic orientation. Similarly, the growth kinetics for various crystal planes is dependent on its crystal orientation apart from local environmental conditions. The combined effects of nucleation & growth kinetics along with solidification conditions dictate the resulting microstructure of an alloy. In this study, various phases of a near eutectic Al-Si alloy are examined by serial sectioning and 3D reconstruction. A peculiar microstructure is observed in which primary silicon is present in the immediate proximity of primary aluminum. Observations through electron back scatter diffraction show that the microtexture of primary and eutectic Si is similar (with in a twin relation) and thus it is concluded that the formation of eutectic starts with eutectic Si forming on the primary Si.