Aeroacoustics of supersonic jet flows from contoured and solid/porous conical plug-nozzles

The results of an experimental study of the acoustic far-field, the shock associated noise, and the nature of the repetitive shock structure of supersonic jet flows issuing from plug-nozzles having externally-expanded plugs with pointed termination operated at a range of supercritical pressure ratios Xi approaching 2 to 4.5 are reported. The plug of one of these plug-nozzles was contoured. The other plug-nozzles had short conical plugs with either a solid surface or a combination of solid/porous surface of different porosities. The contoured and the uncontoured plug-nozzles had the same throat area and the same annulus-radius ratio K = R sub p/R sub N = 0.43. As the result of modifications of the shock structure, the acoustic performance of improperly expanded jet flows of an externally-expanded short uncontoured plug of an appropriate geometry with suitably perforated plug and a pointed termination, is shown to approach the acoustic performance of a shock-free supersonic jet issuing from an equivalent externally-expanded contoured plug-nozzle

Star Clusters in the Magellanic Clouds-1: Parameterisation and Classification of 1072 Clusters in the LMC

We have introduced a semi-automated quantitative method to estimate the age and reddening of 1072 star clusters in the Large Magellanic Cloud (LMC) using the Optical Gravitational Lensing Experiment (OGLE) III survey data. This study brings out 308 newly parameterised clusters. In a first of its kind, the LMC clusters are classified into groups based on richness/mass as very poor, poor, moderate and rich clusters, similar to the classification scheme of open clusters in the Galaxy. A major cluster formation episode is found to happen at 125 +- 25 Myr in the inner LMC. The bar region of the LMC appears prominently in the age range 60 - 250 Myr and is found to have a relatively higher concentration of poor and moderate clusters. The eastern and the western ends of the bar are found to form clusters initially, which later propagates to the central part. We demonstrate that there is a significant difference in the distribution of clusters as a function of mass, using a movie based on the propagation (in space and time) of cluster formation in various groups. The importance of including the low mass clusters in the cluster formation history is demonstrated. The catalog with parameters, classification, and cleaned and isochrone fitted CMDs of 1072 clusters, which are available as online material, can be further used to understand the hierarchical formation of clusters in selected regions of the LMC.Comment: 19 pages, 19figures, published in MNRAS on August 16, 2016 Supplementary material is available in the MNRAS websit

The Dielectric Response of La0.5Ca0.5-xSrxMnO3 (0.1 <= x <= 0.4) Manganites with Different Magnetic Ground States

The dielectric behavior of half doped manganites La0.5Ca0.5-xSrxMnO3 (0.1 \leq \times \leq 0.4) with varying magnetic ground states has been studied. The real part of relative permittivity as a function of temperature {\epsilon}^'(T), exhibits a maximum around the ferromagnetic (TC) and charge ordering transition (TCO) temperatures accompanied with high dielectric losses. The activation energies obtained for x = 0.1 and 0.3 samples below TCO are the same ~ 0.12eV, whereas the relaxation time constant varies in the range 2.8 \times 10-9 s - 6.03 \times 10-11 s. In contrast to samples having x \leq 0.3, for x = 0.4 doping the dielectric permittivity exhibits a strong temperature dependence in the vicinity of magnetic phase transitions. This behavior may be correlated with the presence of competing magnetic interactions (magnetic polarons) close to the magnetic transitions.Comment: 14 pages, 5 figures, To appear in Journal of Applied Physic

An Efficient Multistage Fusion Approach for Smartphone Security Analysis

Android smartphone ecosystem is inundated with innumerable applications mainly developed by third party contenders leading to high vulnerability of these devices. In addition, proliferation of smartphone usage along with their potential applications in diverse field entice malware community to develop new malwares to attack these devices. In order to overcome these issues, an android malware detection framework is proposed wherein an efficient multistage fusion approach is introduced. For this, a robust unified feature vector is created by fusion of transformed feature matrices corresponding to multi-cue using non-linear graph based cross-diffusion. Unified feature is further subjected to multiple classifiers to obtain their classification scores. Classifier scores are further optimally fused employing Dezert-Smarandache Theory (DSmT). Strength of suggested model is assessed both qualitatively and quantitatively by ten-fold cross-validation on the benchmarked datasets. On an average of outcome, we achieved detection accuracy of 98.97% and F-measure of 0.9936.&nbsp

Perceptual and Acoustical assessment of voice in children with cleft lip and palate

BACKGROUND: The speech of individuals with cleft lip and palate is primarily characterized by nasality of oral speech because of cleft and or velopharyngeal dysfunction. OBJECTIVES: The aim of the present study is to investigate the acoustical assessment and perceptual rating measurements in cleft lip and palate children. METHODS: The study participants included 30 children with cleft lip and palate in the age range of 4 to 12 years. Prior parental consent was obtained for the inclusion of their children in the study. Speech samples of all the l the participants were recorded. Prerecorded speech samples of the individuals of the CLP groups were mixed and randomized and played,using headphone conditions in a quiet room. The SLPs speech language pathologists rated the nasality of the participant. Samples given for perceptual evaluation are 15 phonation samples of /ă/, /ɪ/ and /ŭ/ vowels vowel, 15 conversation samples and 30 subjects (3 oral sentences each so total 90 sentences). RESULTS: For the Phonation sample, SLP must evaluate the presence of hypernasality by Wilcoksons nasality scale. Acoustic analysis was done using PRAAT software. The spectral and temporal parameters were measured. The Kappa coefficient was 0.88 for inter-rater reliability for nasality rating scale, 0.82 for speech intelligibility,1.02 for speech understandability,1.00 for speech acceptability, which suggests substantial agreement between the raters for four different rating scales. CONCLUSION: Thus, to conclude in children with cleft lip and palate both acoustical and perceptual evaluation plays an important role while assessing the speech domain by using different kinds of speech stimuli

Geochemical and isotopic signatures for the identification of seawater intrusion in an alluvial aquifer

Seawater intrusion is one of the alarming processes that reduces the water quality and imperils the supply of freshwater in coastal aquifers. The region, north of the Chennai city, India is one such site affected by seawater intrusion. The objective of this study is to identify the extent of seawater intruded area by major geochemical and isotopic signatures. A total of 102 groundwater samples were collected and analysed for major and minor ions. Groundwater samples with electrical conductivity (EC) greater than 5000 μS/cm and a river mouth sample were analyzed for Oxygen-18 (δ 18O) and Deuterium (δ 2H) isotopes to study their importance in monitoring seawater intrusion. The molar ratio of geochemical indicators and isotopic signatures suggests an intrusion up to a distance of 13 km from the sea as on March 2012 and up to 14.7 km during May 2012

STUDY OF RADON AND THORON CONCENTRATION IN ENVIRONMENT OF MORADABAD DISTRICT OF UTTAR PRADESH, INDIA

Purpose: A study of indoor radon and thoron has been carried out in the dwelling of Moradabad, Uttar Pradesh, India. Radon is an invisible radioactive gas that occurs naturally in the indoor atmosphere. It comes from the natural breakdown of uranium in soils and rocks. Lung cancer risk depends upon the concentration of radon, thoron and their decay product in the air. Methodology: The measurements of radon and thoron concentration were carried out by using LR-115 type II plastic track detectors (SSNTD Technique).&nbsp; Findings: In the present study the value of radon concentration from10.5 Bq/m3to 30Bq/m3 with an average19.9Bq/m3and thoron concentration from 5.6 Bq/m3 to 24 Bq/m3 with an average of 14.9 Bq/m3. It is observed that radon and thoron concentration is maximum in winter and minimum during summer. The maximum concentration in winter is essentially influenced by the intense temperature inversion, which occurs in the winter season when the wind velocity is low. The maximum concentration in winter is also the result of decreased ventilation because in this season the houses are closed for a long time and radon/thoron accumulated inside the room and a weak positive correlation was observed between radon and thoron. Social Implications:&nbsp; There are some difficulties in assessing the exact risks of radon in the home. Most studies have used data from miners who will have had far more exposure to radon than is likely in any building. Originality/ Novelty: This study is done at Moradabad City and Research Lab present in S.S.P. G. College Shajhanapur. Data of radon and thoron concentration has been taken from twin cup radon-thoron Dosimeter and Spark Counter