Third order trace formula

In J. Funct. Anal. 257 (2009) 1092-1132, Dykema and Skripka showed the existence of higher order spectral shift functions when the unperturbed self-adjoint operator is bounded and the perturbation is Hilbert-Schmidt. In this article, we give a different proof for the existence of spectral shift function for the third order when the unperturbed operator is self-adjoint (bounded or unbounded, but bounded below).

Non-Destructive Evaluation of Defects and Damage in Composite Materials and Structures

The mechanical behaviour of composite materials differs from that of conventional structural materials owing to their heterogeneous and anisotropic nature. Different types of defects and anomalies get induced in these materials during the fabrication process. Further, during their service life, the components made of composite materials develop different types of damage. The performance and life of such components is governed by the combined effect of all these defects and damage. While porosity, voids, inclusions etc., are some defects those can get induced during the fabrication of composites, matrix cracks, interface debonds, delaminations and fiber breakage are major types of service induced damage which are of concern. During the service life of components made of composites, one type of damage can grow and initiate another type of damage. For example, matrix cracks can gradually grow to the interface and initiate debonds. Interface debonds in a particular plane can lead to delaminations. Consequently, the combined effect of different types of distributed damage causes the failure of the component. A set of non-destructive evaluation (NDE) methods is well established for testing conventional metallic materials. Some of them can also be utilized for composite materials as they are, and in some cases with a little different approach or modification. Ultrasonics, Radiography, Thermography, Fiber Optics, Acoustic Emision Techniques etc., to name a few. Detection, evaluation and characterization of different types of defects and damage encountered in composite materials and structures using different NDE tools is discussed briefly in this paper.

Glacial mass balance changes in the Karakoram and Himalaya based on CMIP5 multi-model climate projections

The impact of future climate change on the glaciers in the Karakoram and Himalaya (KH) is investigated using CMIP5 multi-model temperature and precipitation projections, and a relationship between glacial accumulation-area ratio and mass balance developed for the region based on the last 30 to 40 years of observational data. We estimate that the current glacial mass balance (year 2000) for the entire KH region is -6.6 +/- 1 Gta(-1), which decreases about sixfold to -35 +/- 2 Gta(-1) by the 2080s under the high emission scenario of RCP8.5. However, under the low emission scenario of RCP2.6 the glacial mass loss only doubles to -12 +/- 2 Gta(-1) by the 2080s. We also find that 10.6 and 27 % of the glaciers could face `eventual disappearance' by the end of the century under RCP2.6 and RCP8.5 respectively, underscoring the threat to water resources under high emission scenarios.

Direct Characterizing of Densification Mechanisms during Spark Plasma Sintering

Spark plasma sintering (SPS) is a convenient and rapid means of producing dense ceramic compacts. However, the mechanisms responsible for rapid densification have not been identified satisfactorily, with different studies using an indirect approach yielding varied values for the densification parameters. This study involved SPS in high purity nanocrystalline alumina with temperatures ranging from 1173 to 1423K and stresses from 25 to 100MPa. A direct approach, with analyses at a constant density, revealed a stress exponent of similar to 1 and an inverse grain size dependence of similar to 3, consistent with Coble creep process. Whereas the direct approach gives a stress exponent of similar to 1, the indirect approach used previously gives stress exponents ranging from similar to 2.2 to 3.5 with the same data, thereby revealing potentially spurious values of the densification parameters from conventional indirect approaches to characterizing densification. The rapid densification during SPS is related to the finer grain sizes retained with the rapid heating rates and the imposed stress that enhances the driving force for densification.

Conditional silencing of topoisomerase I gene of Mycobacterium tuberculosis validates its essentiality for cell survival

Topoisomerases are an important class of enzymes for regulating the DNA transaction processes. Mycobacterium tuberculosis (Mtb) is one of the most formidable pathogens also posing serious challenges for therapeutic interventions. The organism contains only one type IA topoisomerase (Rv3646c), offering an opportunity to test its potential as a candidate drug target. To validate the essentiality of M.tuberculosis topoisomerase I (TopoI(Mt)) for bacterial growth and survival, we have generated a conditionally regulated strain of topoI in Mtb. The conditional knockdown mutant exhibited delayed growth on agar plate. In liquid culture, the growth was drastically impaired when TopoI expression was suppressed. Additionally, novobiocin and isoniazid showed enhanced inhibitory potential against the conditional mutant. Analysis of the nucleoid revealed its altered architecture upon TopoI depletion. These studies establish the essentiality of TopoI for the M.tuberculosis growth and open up new avenues for targeting the enzyme.

Development of design charts for stress intensity factors at tips of multi-site cracks in unstiffened curved panels

Multi-site damage need to be addressed and evaluated in order to assess the integrity of aging aircraft structures. One of the problems recognized in the recent times is the effect of interaction between two or more cracks in the close neighborhood in such structures. The present paper deals with such a problem and presents numerical estimates of stress intensity factors at a crack tip in an un-stiffened curved panel with a secondary crack in the vicinity of a primary crack. The results are presented in the form of design charts. These results should be useful in evaluation in the damage tolerance evaluation of aircraft structures with multi-site damage. (C) 2014 Elsevier Ltd. All rights reserved.

Comprehensive seismic hazard assessment of Tripura and Mizoram states

Northeast India is one of the most highly seismically active regions in the world with more than seven earthquakes on an average per year of magnitude 5.0 and above. Reliable seismic hazard assessment could provide the necessary design inputs for earthquake resistant design of structures in this' region. In this study, deterministic as well as probabilistic methods have been attempted for seismic hazard assessment of Tripura and Mizoram states at bedrock level condition. An updated earthquake catalogue was collected from various national and international seismological agencies for the period from 1731 to 2011. The homogenization, declustering and data completeness analysis of events have been carried out before hazard evaluation. Seismicity parameters have been estimated using G R relationship for each source zone. Based on the seismicity, tectonic features and fault rupture mechanism, this region was divided into six major subzones. Region specific correlations were used for magnitude conversion for homogenization of earthquake size. Ground motion equations (Atkinson and Boore 2003; Gupta 2010) were validated with the observed PGA (peak ground acceleration) values before use in the hazard evaluation. In this study, the hazard is estimated using linear sources, identified in and around the study area. Results are presented in the form of PGA using both DSHA (deterministic seismic hazard analysis) and PSHA (probabilistic seismic hazard analysis) with 2 and 10% probability of exceedance in 50 years, and spectral acceleration (T = 0. 2 s, 1.0 s) for both the states (2% probability of exceedance in 50 years). The results are important to provide inputs for planning risk reduction strategies, for developing risk acceptance criteria and financial analysis for possible damages in the study area with a comprehensive analysis and higher resolution hazard mapping.

Bioremediation and lipid synthesis through mixotrophic algal consortia in municipal wastewater

Algae grown in outdoor reactors (volume: 10 L and depth: 20 cm) were fed directly with filtered and sterilised municipal wastewater. The nutrient removal efficiencies were 86%, 90%, 89%, 70% and 76% for TOC, TN, NH4-N, TP and OP, respectively, and lipid content varied from 18% to 28.5% of dry algal biomass. Biomass productivity of similar to 122 mg/l/d (surface productivity 24.4 g/m(2)/d) and lipid productivity of similar to 32 mg/l/d were recorded. Gas chromatography and mass spectrometry (GC-MS) analyses of the fatty acid methyl esters (FAME) showed a higher content of desirable fatty acids (bearing biofuel properties) with major contributions from saturates such as palmitic acid C16:0; similar to 40%] and stearic acid C18:0; similar to 34%], followed by unsaturates such as oleic acid C18:1(9); similar to 10%] and linoleic acid C18:2(9,12); similar to 5%]. The decomposition of algal biomass and reactor residues with an exothermic heat content of 123.4 J/g provides the scope for further energy derivation. (C) 2014 Elsevier Ltd. All rights reserved.

Comparison of CO2 and steam in transcritical Rankine cycles for concentrated solar power

High temperature, high pressure transcritical condensing CO2 cycle (TC-CO2) is compared with transcritical steam (TC-steam) cycle. Performance indicators such as thermal efficiency, volumetric flow rates and entropy generation are used to analyze the power cycle wherein, irreversibilities in turbo-machinery and heat exchangers are taken into account. Although, both cycles yield comparable thermal efficiencies under identical operating conditions, TC-CO2 plant is significantly compact compared to a TC-steam plant. Large specific volume of steam is responsible for a bulky system. It is also found that the performance of a TC-CO2 cycle is less sensitive to source temperature variations, which is an important requirement of a solar thermal system. In addition, issues like wet expansion in turbine and vacuum in condenser are absent in case of a TC-CO2 cycle. External heat addition to working fluid is assumed to take place through a heat transfer fluid (HTF) which receives heat from a solar receiver. A TC-CO2 system receives heat though a single HTF loop, whereas, for TC-steam cycle two HTF loops in series are proposed to avoid high temperature differential between the steam and HTF. (C) 2013 P. Garg. Published by Elsevier Ltd.

Effect of High-Pressure Torsion on Texture, Microstructure, and Raman Spectroscopy: Case Study of Fe- and Te-Substituted CoSb3

Fe0.05Co0.95Sb2.875Te0.125, a double-element-substituted skutterudite, was prepared by induction melting, annealing, and hot pressing (HP). The hot-pressed sample was subjected to high-pressure torsion (HPT) with 4 GPa pressure at 673 K. X-ray diffraction was performed before and after HPT processing of the sample; the skutterudite phase was observed as a main phase, but an additional impurity phase (CoSb2) was observed in the HPT-processed sample. Surface morphology was determined by high-resolution scanning electron microscopy. In the HP sample, coarse grains with sizes in the range of approximately 100 nm to 300 nm were obtained. They changed to fine grains with a reduction in grain size to 75 nm to 125 nm after HPT due to severe plastic deformation. Crystallographic texture, as measured by x-ray diffraction, indicated strengthening of (112), (102) poles and weakening of the (123) pole of the HPT-processed sample. Raman-active vibrational modes showed a peak position shift towards the lower energy side, indicating softening of the modes after HPT. The distortion of the rectangular Sb-Sb rings leads to broadening of Sb-Sb vibrational modes due to local strain fluctuation. In the HPT process, a significant effect on the shorter Sb-Sb bond was observed as compared with the longer Sb-Sb bond.

Sensitivity of meteorological input and soil properties in simulating aerosols (dust, PM10, and BC) using CHIMERE chemistry transport model

The objective of this study is to evaluate the ability of a European chemistry transport model, `CHIMERE' driven by the US meteorological model MM5, in simulating aerosol concentrations dust, PM10 and black carbon (BC)] over the Indian region. An evaluation of a meteorological event (dust storm); impact of change in soil-related parameters and meteorological input grid resolution on these aerosol concentrations has been performed. Dust storm simulation over Indo-Gangetic basin indicates ability of the model to capture dust storm events. Measured (AERONET data) and simulated parameters such as aerosol optical depth (AOD) and Angstrom exponent are used to evaluate the performance of the model to capture the dust storm event. A sensitivity study is performed to investigate the impact of change in soil characteristics (thickness of the soil layer in contact with air, volumetric water, and air content of the soil) and meteorological input grid resolution on the aerosol (dust, PM10, BC) distribution. Results show that soil parameters and meteorological input grid resolution have an important impact on spatial distribution of aerosol (dust, PM10, BC) concentrations.

Multicomponent Assembly of Fluorescent-Tag Functionalized Ligands in Metal-Organic Frameworks for Sensing Explosives

Detection of trace amounts of explosive materials is significantly important for security concerns and pollution control. Four multicomponent metal organic frameworks (MOFs-12, 13, 23, and 123) have been synthesized by employing ligands embedded with fluorescent tags. The multicomponent assembly of the ligands was utilized to acquire a diverse electronic behavior of the MOFs and the fluorescent tags were strategically chosen to enhance the electron density in the MOFs. The phase purity of the MOFs was established by PXRD, NMR spectroscopy, and finally by singlecrystal XRD. Single-crystal structures of the MOFs-12 and 13 showed the formation of three-dimensional porous networks with the aromatic tags projecting inwardly into the pores. These electron-rich MOFs were utilized for detection of ex- plosive nitroaromatic compounds (NACs) through fluorescence quenching with high selectivity and sensitivity. The rate of fluorescence quenching for all the MOFs follows the order of electron deficiency of the NACs. We also showed the detection of picric acid (PA) by luminescent MOFs is not always reliable and can be misleading. This attracts our attention to explore these MOFs for sensing picryl chloride (PC), which is as explosive as picric acid and used widely to prepare more stable explosives like 2,4,6-trinitroaniline from PA. Moreover, the recyclability and sensitivity studies indicated that these MOFs can be reused several times with parts per billion (ppb) levels of sensitivity towards PC and 2,4,6-trinitrotoluene (TNT).

PolyGLoT: A Polyhedral Loop Transformation Framework for a Graphical Dataflow Language

Polyhedral techniques for program transformation are now used in several proprietary and open source compilers. However, most of the research on polyhedral compilation has focused on imperative languages such as C, where the computation is specified in terms of statements with zero or more nested loops and other control structures around them. Graphical dataflow languages, where there is no notion of statements or a schedule specifying their relative execution order, have so far not been studied using a powerful transformation or optimization approach. The execution semantics and referential transparency of dataflow languages impose a different set of challenges. In this paper, we attempt to bridge this gap by presenting techniques that can be used to extract polyhedral representation from dataflow programs and to synthesize them from their equivalent polyhedral representation. We then describe PolyGLoT, a framework for automatic transformation of dataflow programs which we built using our techniques and other popular research tools such as Clan and Pluto. For the purpose of experimental evaluation, we used our tools to compile LabVIEW, one of the most widely used dataflow programming languages. Results show that dataflow programs transformed using our framework are able to outperform those compiled otherwise by up to a factor of seventeen, with a mean speed-up of 2.30x while running on an 8-core Intel system.

Phase relations in the system Ca-Ta-O and thermodynamics of calcium tantalates in relation to calciothermic reduction of Ta2O5

Phase equilibria of the system Ca-Ta-O is established by equilibrating eleven samples at 1200 K for prolonged periods and phase identification in quenched samples by optical and scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Four ternary oxides are identified: CaTa4O11, CaTa2O6, Ca2Ta2O7 and Ca4Ta2O9. Isothermal section of the phase diagram is composed using the results. Thermodynamic properties of the ternary oxides are measured in the temperature range from 975 to 1275 K employing solid-state galvanic cells incorporating single crystal CaF2 as the solid electrolyte. The cells essentially measure the chemical potentials of CaO in two-phase fields (Ta2O5 + CaTa4O11), (CaTa4O11 + CaTa2O6), (CaTa2O6 + Ca2Ta2O7), and (Ca2Ta2O7 + Ca4Ta2O9) of the pseudo-binary system CaO-Ta2O5. The standard Gibbs energies of formation of the four ternary oxides from their component binary oxides Ta2O5 and CaO are given by: Delta G(f)((ox))(o) (CaTa4O11) (+/- 482)/J mol(-1) = -58644+21.497 (T/K) Delta G(f)((ox))(o) (CaTa2O6) (+/- 618)/J mol(-1) = -55122+21.893 (T/K) Delta G(f)((ox))(o) (Ca2Ta2O7) (+/- 729)/J mol(-1) = -82562+31.843 (T/K) Delta G(f)((ox))(o) (Ca4Ta2O9) (+/- 955)/J mol(-1) = -126598+48.859 (T/K) The Gibbs energy of formation of the four ternary compounds obtained in this study differs significantly from that reported in the literature. The thermodynamic data and phase diagram are used for understanding the mechanism and kinetics of calciothermic and electrochemical reduction of Ta2O5 to metal. (C) 2014 Elsevier B.V. All rights reserved.