287 research outputs found
Solar Inertial Modes
No full textAbstract The Sun’s global inertial modes are very sensitive to the solar differential rotation and to properties of the deep solar convection zone which are currently poorly constrained. These properties include the superadiabatic temperature gradient, the latitudinal entropy gradient, and the turbulent viscosity. The inertial modes also play a key role in controlling the Sun’s large-scale structure and dynamics, in particular the solar differential rotation. This paper summarizes recent observations and advances in the (linear and nonlinear) modeling of the solar inertial modes
One pot molten salt synthesis and photocatalytic studies of magnetically separable copper ferrite microcrystals
No full textThe preparation of tetragonal and cubic structured CuFe2O4 microcrystals by the one-pot molten salt synthesis in a eutectic mixture of NaCl - KCl molten salts at 800–900 °C is reported. Phase evolution and single-phase formation of CuFe2O4 on temperature and soaking period effect were studied. The structure and morphology of the synthesized compounds were investigated using techniques such as powder X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Microscopy studies revealed microcrystals of CuFe2O4 in an octahedron morphology. Photoluminescence and X-ray photoelectron spectroscopy analysis revealed the existence of surface oxygen defects on both prepared compounds. The photocatalytic studies of tetragonal and cubic structured CuFe2O4 catalysts shown 89% and 93% degradation of the Rhodamine-B (RhB) dye, respectively, under UV-A (366 nm) irradiation in 90 min. Photocatalytic and magnetic studies indicate that these CuFe2O4 samples are suitable magnetic separable photocatalysts for efficient dye degradation, and can be reasonably reused.Fil: Koppala, Sivasankar. Kunming University Of Science And Technology; ChinaFil: Balan, Ramdas. Cmr Institute Of Technology; IndiaFil: Litter, Marta Irene. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Xu, Lei. Kunming University Of Science And Technology; ChinaFil: Li, Kangqiang. Beihang University; ChinaFil: Liu, Hua. Ecole Centrale de Lille Cit´e Scientifique; FranciaFil: Lekshmi, I.C.. Cmr Institute Of Technology; IndiaFil: Begam Mohamed, Rigana. No especifíca
Science & technology agenda for blue-green spaces inspired by citizen science: case for rejuvenation of powai lake
No full textUrban lakes play a major role in the socio-cultural and ecological sustainability of many cities, but are often under major development and pollution pressures. Urban decision makers are faced with a challenging task of identifying the causes of their decline and building plans for their conservation or rejuvenation. Powai Lake is a perfect example of an urban water body with historic, cultural, and ecological importance to the population of Metropolitan Mumbai, with local and regional authorities, including the Urban Development Department, Government of Maharashtra, working to identify methods for rejuvenating the Lake. In this context, characterization of pollution dynamics, hotspots, and extent is fundamental to the development of management plans and appropriate technologies for the remediation and rejuvenation of Powai Lake—the long-term goal of the present study. A two-year monitoring program at eight sampling locations on the Lake’s periphery, with the engagement of citizen scientists along with environmental researchers, revealed clear seasonal and spatial dynamics that allowed for the identification of pollution drivers and the development of a three-phase rejuvenation plan. The plan represents a novel and holistic approach that recognizes Powai Lake as a complex system with multiple drivers, and aims at ecological balance and sustainable delivery of ecosystem services
Single Channel Speech Separation with Frame-based Summary Autocorrelation Function Analysis
No full textAbstractSingle channel speech separation system with frame based pitch range estimation is presented. The system decomposes the input mixture speech into frames and pitch of the speech is estimated in each frame of modulation spectrum by using summary autocorrelation function (SACF) analysis. In this method, each frame is divided into two, above and below 1 KHz and compute generalized autocorrelation for periodicity detection. By using this pitch range, a mask is created to filter the target speech from noisy mixture speech. Performance evaluation of the proposed system shows a better response compared to the existing methods
A Model for Pitch Estimation Using Wavelet Packet Transform Based Cepstrum Method
No full textAbstractA computationally efficient model for pitch estimation of mixed audio signals is presented. Pitch estimation plays a significant role in music audition like music information retrieval, automatic music transcription, melody extraction etc. The proposed system consists of channel separation and periodicity detection. The input signal is created by mixing two sound signals. First removes the short time correlations of the mixed signal. The model divides the signal into number of channels using wavelet packet transform. Computes the cepstrum of each channel and sums the cepstrum functions. The summary cepstrum function is further processed to extract the pitch frequency of two input signal separately. The model performance is demonstrated to be comparable to those of recent multichannel models. The proposed system can be verified by simulating the system in MATLAB
Solar Cycle Variation of Large Scale Plasma Flows
No full textLarge scale plasma flows like differential rotation, and meridional flow play an important role in driving the solar dynamo process. Our long-term study of the hemispherical asymmetry in torsional oscillation and meridional flow show that there exists a time delayed correlation (anti-correlation) between the asymmetries in torsional oscillation (meridional flow) and the sunspot cycle, with the asymmetry in the flows preceding the cycle asymmetry
Time-Dependent Reliability Analysis of Pavement Structures under Fatigue Loading
No full textThe premature failure of well-designed structures in the field is a problem commonly observed worldwide. These early failures and the deterioration in structural resistance of pavements can be attributed to the loading and external environmental factors, damage and improper maintenance during the design life among other factors. The time dependence of performance in the formulation of the reliability problem helps to include the effects of degradation of resistance and the variation of loading with time. In this study, the effect of degradation of the surface layer modulus on the fatigue reliability of pavements is analyzed, where the decrease in the modulus with time is considered as a function of the accumulated damage due to repeated loading. The pavement section considered in the study designed for a period of 15 years at a reliability level of 80%, is seen to have a probability of failure of around 50% after 8 years and 75% after 10 years, when strength degradation is considered. This emphasizes the need for capturing the temporal characteristics of the materials and loading in a time-dependent reliability analysis framework
Indigenous Technical Knowledge and ancient proverbs of the coastal fisher folk of Kerala and their implications
No full textThe paper attempts to study the Indigenous Technical Knowledge of the fisher folk offishing villages. Maruvakkad and
Mallipuram belonging to Chellanam and Elankunnapuzha Panchayats. respectively of Palluruthy and Vypeen Block,
Ernakulam. The Traditional knowledge and proverbs penaining to the fishing community of these villages were collected
and the scientific rationale for the same was studied
Security challenges in cloud storage
No full textAs cloud becomes the tool of choice for more data storage services, the number of service providers has also increased. With these choices, organisations have a wide selection of services available to move their data to the cloud. However, the responsibility to maintain the security of sensitive data stored therein remains paramount. This paper will discuss some of the challenges of securing a cloud storage and putting it into context by reviewing relevant literature. The challenges associated with the three important security aspects (confidentiality, integrity and availability) are discussed together with the vulnerabilities linked to them. It is important to look into these challenges as cloud storage is not only about technological evolution but involves security considerations. We aim to provide insights of security challenges and its solutions to enhance cloud storage implementation
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