Tunable Assembly of sp3 Cross‐Linked 3D Graphene Monoliths: A First‐Principles Prediction

One of the biggest challenges in graphene applications is how one can fabricate 3D architectures comprising graphene sheets in which the resulting architectures have inherited graphene's excellent intrinsic properties but have overcome its shortcomings. Two series of 3D graphene monoliths (GMs) using zigzag or armchair graphene nanoribbons as building blocks and sp³ carbon chains as junction nodes are constructued, and calculations based on first principles are performed in order to predict their mechanical and electronic properties. The perfect match between sp² nanoribbons and sp³ linkers results in favorable energy and mechanical/dynamic stability. Owing to their tailored motifs, wine‐rack‐like pores, and rigid sp³ linkers, these GMs possess high surface areas, appreciable mechanical strength, and tunable band gaps. Negative linear compressibilities in a wide range are found for the zigzag GMs. By solving the problems of zero gap and dimensionality of graphene sheets simultaneously, these GMs offer a viable strategy towards many applications, e.g., microelectronic devices, energy storage, molecular sieves, sensitive pressure detectors, and telecommunication line systems.     

Ion Chromatographic Analysis of Ammonium Dinitramide–Oxidizer for Propellant and Pyrotechnic Applications

Analysis of ammonium dinitramide (ADN), the advance rocket propellant oxidizer, in pure form as well as in mixtures was carried out by ion chromatography (IC). The purity of ammonium dinitramide was directly determined by estimating the dinitramide ions and indirectly by estimating the impurities. Both methods gave results comparable with those determined by Differential Scanning Calorimetry and UV spectroscopy. The chemical composition of ADN in mixtures containing nitrate, chromate, chlorate, perchlorate, and thiocyanate ions was quantitatively estimated in the same solution without any interferences or prior separation of analyte ions. The newly developed ion chromatographic methods for the analysis of ADN are simple and fast with good accuracy and precision when compared to other analytical techniques. The IC methods are found to be highly suitable for quality control analysis of ADN containing compositions and for the online process monitoring of the formation of ADN in the reaction mixture.     

Performance comparison of quadrature amplitude modulation (QAM)-based single- and double-stage digital interpolators

In this article, the performance of quadrature amplitude modulation (QAM)-based single- and double-stage digital interpolators have been compared. The basic interpolator for up-sampling can be a combination of an expander unit with an interpolation lowpass filter in cascade. Complicated implementations can be done by connecting multiple expander and low-pass filter pairs in cascade. This article presents the efficient and effective implementation of digital interpolation systems for up-sampling of single- and double-stage digital interpolators. Comparison is done in terms of spectrum of generated signal, envelope power, modulated signal trajectory, input and output constellation and noise performance. In this article, the proposed interpolation filters have been simulated in Agilent's Advanced Design System (ADS).     

Wavelet based denoising technique for liquid level system

The purpose of this paper is to employ wavelet based noise removal technique to remove measurement noise from differential pressure transmitter (DPT) output indicating the level of a process tank. The liquid level system (LLS) is approximated as a first order plant with time delay. When connected in closed loop, the LLS is ideally associated with a PI controller, an actuator, a final control element and a level sensor (DP transmitter in present system). There are enough chances of contaminating the output of LLS by the high frequency measurement noise. In this work, an attempt has been made to judge the performance of discrete wavelet transform (DWT) and discrete wavelet packet transform (DWPT) based noise removal technique when applied to LLS. The available denoised response using wavelet based filtering is compared with that of conventional Butterworth filtering method. Applying hard thresholding that typically retains a very small number of coefficients, the results are often smoothed at the cost of loosing information. By retaining larger number of coefficients and shrinking them, the soft thresholding methods usually give more useful results to denoise the signal. Threshold value has been calculated by Visu Shrink method and Minimax method in different cases.     

Oxidation resistance of nanocrystalline vis-à-vis microcrystalline Fe-Cr alloys

This paper investigates the hypothesis that nanocrystalline structure may confer considerable oxidation resistance to iron-chromium alloys at much lower chromium contents. Discs of nanocrystalline Fe-10%Cr alloy were produced by ball milling of Fe and Cr powders and compaction of the powder without considerable grain growth (by processing within a suitable time-temperature window). Corrosion resistance of discs of nanocrystalline and microcrystalline alloys was compared by subjecting them to oxidation in air and post-oxidation characterisation of the oxide scales by secondary ion mass spectroscopy (SIMS). Nanocrystalline Fe-10%Cr alloy showed considerably greater oxidation resistance than the microcrystalline alloy of the same composition. Chromium content of the inner scale formed over the nanocrystalline alloy was detected to be nearly five times greater than that in the case of microcrystalline alloy, facilitating formation of the passive layer and providing an explanation for the greater oxidation of the former.     

Title: A study of the implications of air cooling of hot-rolled asymmetrical sections

The air cooling pattern across hot-rolled structural steel sections was investigated, and a regression equation for the heat-transfer coefficient for a typical section was developed. The nonuniform cooling of stock leads to camber, which necessitates straightening and thereby influences the residual stress pattern across the section. Some microstructural variations were also found to have resulted from the nonuniformity in cooling rates.     

Bio‐diesel lubricity: correlation study with residual acidity

Bio‐diesel has been accepted as a renewable liquid biofuel worldwide. In order to ensure customers' acceptance, standardisation and quality assurance are the key factors to the market introduction of bio‐diesel as a transport fuel. Lubricity of bio‐diesel is an important issue and it is well reported that 1–2% bio‐diesel is sufficient to maintain the lubricity of diesel even of very poor lubricity. However, a wide variation in lubricity performance of bio‐diesel from different vegetable oils and sources has been noticed. In addition, on critical examination, it was noticed that the variation in the lubricating performance of bio‐diesel could be better linked to its residual acidity than to variation in fatty acid composition. Copyright © 2007 John Wiley & Sons, Ltd.     

Adsorptive removal of Erythrosine dye onto activated low cost de-oiled mustard

The present paper is aimed to investigate and develop cheap adsorption methods for colour removal from wastewater using waste material de-oiled mustard as adsorbent. De-oiled mustard, a biosorbent, was successfully utilized for removing a water-soluble xanthene dye, Erythrosine from wastewater. Kinetic studies of adsorption of Erythrosine at de-oiled mustard were carried out at 30 degrees C, using aqueous solutions with 5 x 10(-5)M concentration of Erythrosine. The adsorption process followed a pseudo-first order model. The equilibrium process can be well described by both Freundlich and Langmuir models, at 30, 40 and 50 degrees C. Free energy of adsorption (DeltaG degrees ), enthalpy (DeltaH degrees ), and entropy (DeltaS degrees ) changes were calculated to predict the nature of adsorption. The estimated values for DeltaG degrees were -12.81 x 10(3) and -12.57 x 10(3) over activated carbon and activated de-oiled mustard at 203 K (30 degrees C), indicate toward a spontaneous process. The positive value for DeltaH degrees indicates that the adsorption of Erythrosine dye to de-oiled mustard is an endothermic process.     

A Discrete Water Cycle Algorithm for Cellular Network Cost Management

Wireless Personal Communications - Water Cycle Algorithm (WCA) is a nature-inspired metaheuristic algorithm. There is a lack of literature surrounding the use of WCA in modern cellular mobile...