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1.
Density based clustering algorithms(DBCLAs)rely on the notion of density to identify clusters of arbitrary shapes,sizes with varying densities.Existing surveys on DB-CLAs cover only a selected set of algorithms.These surveys fail to provide an extensive information about a variety of DBCLAs proposed till date including a taxonomy of the algorithms.In this paper we present a comprehensive survey of various DB-CLAS over last two decades along with their classification.We group the DBCLAs in each of the four categories:density definition,parameter sensitivity,execution mode and nature of*data and further divide them into various classes under each of these categories.In addition,we compare the DBCLAs through their common features and variations in citation and conceptual dependencies.We identify various application areas of DBCLAS in domains such as astronomy,earth sciences,molecular biology,geography,multimedia.Our survey also identifies probable future directions of DBCLAs where involvement of density based methods may lead to favorable results. 相似文献
2.
Diversity of culturable bacterial populations within the Arsenic (As) contaminated groundwater of North Eastern state (Assam) of India is studied. From nine As contaminated samples 89 bacterial strains are isolated. 16S rRNA gene sequence analysis reveals predominance of Brevundimonas (35%) and Acidovorax (23%) along with Acinetobacter (10%), Pseudomonas (9%) and relatively less abundant (<5%) Undibacterium, Herbaspirillum, Rhodococcus, Staphylococcus, Bosea, Bacillus, Ralstonia, Caulobacter and Rhizobiales members. High As(III) resistance (MTC 10–50 mM) is observed for the isolates obtained from As(III) enrichment, particularly for 3 isolates of genus Brevundimonas (MTC 50 mM). In contrast, high resistance to As(V) (MTC as high as 550 mM) is present as a ubiquitous property, irrespective of isolates' enrichment condition. Bacterial genera affiliated to other groups showed relatively lower degree of As resistance [MTCs of 15–20 mM As(III) and 250–350 mM As(V)]. As(V) reductase activity is detected in strains with high As(V) as well as As(III) resistance. A strong correlation could be established among isolates capable of reductase activity and siderophore production as well as As(III) tolerance. A large number of isolates (nearly 50%) is capable of anaerobic respiration using alternate inorganic electron acceptors [As(V), Se(VI), Fe(III), 3NO2−, 4SO2−, S2O32−]. Ability to utilize different carbon sources ranging from C2–C6 compounds along with some complex sugars is also observed. Particularly, a number of strains is found to possess ability to grow chemolithotrophically using As(III) as the electron donor. The study reports for the first time the identity and metabolic abilities of bacteria in As contaminated ground water of North East India, useful to elucidate the microbial role in influencing mobilization of As in the region. 相似文献
3.
Pinaki Majumdar Sabyasachi Tarat 《Journal of Superconductivity and Novel Magnetism》2013,26(5):1787-1793
The mean field theory due to Bardeen, Cooper, and Schrieffer (BCS) provides the conceptual foundation of our understanding of superconductivity, but many examples over the last few decades have forced condensed matter physicists to extend the BCS framework. In particular, the extension to strong coupling, the BCS to Bose–Einstein condensation (BEC) crossover, requires the treatment of amplitude and phase fluctuations above the mean field state. Similarly, the presence of disorder can lead to strong inhomogeneity in the pairing amplitude, enhance phase fluctuations, and suppress the transition temperature. Finally, magnetic scattering quickly leads to a gapless superconducting state and then the loss of order. All of these involve physics beyond the BCS scenario. We employ a real space method that reduces to inhomogeneous mean field theory in the ground state, but fully retains the amplitude and phase fluctuations of the pairing field at finite temperature. This paper reviews some of our work in the weak to strong coupling (BCS–BEC) crossover, the disorder driven superconductor-insulator transition, and the role of magnetic impurities. 相似文献
4.
Virtual microstructures having a systematic variation of amount, mean size, standard deviation of size, and spatial arrangement
of intermetallics have been synthesized, and their deformation behavior in uniaxial tension has been evaluated using finite
element analysis. Four spatial arrangements of intermetallics have been considered in this work, namely: random, clustered,
and two-ordered structures. Various mathematical quantities have been developed to quantify the severity of deformation including
plastic work density distribution (PWDD), percentile work-density volume criterion (PWC), and percentile stress volume criterion
(PSC). This approach eliminates the need for an external trigger in FEA to achieve localization. The method developed has
led to a better understanding of the effect of different microstructural attributes on the process of deformation. This has
resulted in guidelines for optimizing the microstructure to minimize material damage and thereby maximize ductility. 相似文献
5.
In this paper, we define generalised fuzzy soft sets and study some of their properties. Application of generalised fuzzy soft sets in decision making problem and medical diagnosis problem has been shown. 相似文献
6.
Anil Kumar Mandeep Kaur Rajeev Kumar Pinaki Ranjan Sengupta Vasantha Raman Gopal Bhatia Kedar Nath Sood 《Journal of Materials Science》2010,45(5):1393-1400
Carbon–copper composites with varying copper to carbon ratio of 0.66–1.5 (by weight) were developed from coal-tar-pitch-derived
green coke (as such or modified with natural graphite) as carbon source and electrolytic grade copper powder at different
heat treatment temperatures (HTTs) of 1000–1400 °C. The physical, mechanical, and electrical properties differ depending upon
the HTT and also on copper to carbon ratio (Cu/C). The composites prepared at HTT of 1100 °C having Cu/C ratio of 0.66 and
0.9 exhibited a high bending strength of 150 and 140 MPa, bulk density of 2.63 and 2.81 gm/cm3, electrical resistivity of 1.6 and 0.96 m Ω cm and shore hardness of 88 and 84, respectively, in spite of well-known inadequate
wettability between copper and carbon. Increasing the temperature from 1100 °C for processing of the composites deteriorated
the properties mainly due to the loss of copper through melting above 1100 °C as revealed by X-ray, scanning electron microscopy,
thermal analysis and EDAX studies. 相似文献
7.
Kausik Chattopadhyay Pinaki Mandal Patrice Lerouge Azeddine Driouich Pradyot Ghosal Bimalendu Ray 《Food chemistry》2007,104(3):928-935
Heteroglycan and xyloglucan rich fractions were extracted from Indian samples of Enteromorpha compressa in 25% yield by sequential extractions with water and alkali. This heteroglycan is sulfated and has an apparent molecular mass of 55 kDa. Chemical structural analysis of this polysaccharide revealed a branched structure having 1,4- and 1,2,4-linked rhamnose 3-sulphate, 1,4-linked glucose, 1,3- and 1,6- linked galactose, 1,4- and terminally linked glucuronic acid and 1,4-linked xylose partially sulfated on O-2. Chemical and spectroscopic analysis showed that the 4-M KOH extracted hemicellulosic fraction contained an unusual β-(1,4)-linked linear xyloglucan. Enzyme hydrolysis and analysis of the resulting fragments by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) showed that this linear polymer contained partially sulfated Glc3Xyl2 or Glc4Xyl2 as oligomeric building subunits. 相似文献
8.
Debapriya Pinaki Mohanty Laxminarsimha Rao V. Animangsu Ghatak 《Journal of Adhesion Science and Technology》2013,27(15):1647-1657
When a stack consisting of layers of soft elastomer and thin metallic film is subjected to low intensity impact by releasing an axisymmetric spherical indenter from a vertical height, the foils buried within the stack undergoes large deformation and fracture. The shape of the deformed area nevertheless remains circular, its radius first increases with the depth from the surface of the stack and then decreases. In contrast, here we show that the symmetry of the deformed area breaks down when instead of a smooth elastomeric layer, one with topographical patterns is used in the stack. The metallic foil deforms through a polygonal area. The size and shape of the polygonal area vary with the flexibility of foil, geometry and dimension of the patterns and the intensity of the impact. For example, for one elastomeric layer decorated with pillars arranged in a square array, the damaged area turns rectangular to hexagonal and then to octagonal with increasing severity of impact, very much similar to polygonal wetting and spreading by a liquid on a patterned substrate. 相似文献
9.
A detailed experimental investigation has been made on the electronic tuning of resonant-cap IMPATT oscillators at the X-band. The investigation is extended to include mechanical tuning properties, i.e. studies on the dependence of the tuning properties on the resonant-cap diameter and the cap height. The study of electronic tuning gives an interesting insight regarding tuning behaviour for various ranges of d.c. bias current. From the study of these tuning properties the optimum size of the resonant-cap cavity for realizing maximum power output and electronic tunability for a given IMPATT diode can be obtained, which would be useful in the design of resonant-cap IMPATT oscillators. 相似文献
10.
Tapas Kumar Maiti Satya Sopan Mahato Pinaki Chakraborty Chinmay Kumar Maiti Subir Kumar Sarkar 《Journal of Computational Electronics》2010,9(1):1-7
Negative Bias Temperature Instability (NBTI) in p-MOSFETs is a serious reliability concern for digital and analog CMOS circuit
applications. Strain in the channel region affects negative bias temperature instabilities, low frequency noise, radiation
hardness, gate oxide quality and hot carrier performance. The understanding of these phenomena in strain-engineered p-MOSFETs
from fundamental physics is essential. In this paper, technology CAD (TCAD) has been used to study the effects of strain on
the negative bias temperature instabilities in p-MOSFETs. A quasi two dimensional (quasi-2D) physics-based Coulomb scattering
mobility model for strained-Si has been developed and implemented in Synopsys Sentaurus Device tool for device simulation
to understand NBTI in strain-engineered p-MOSFETs. 相似文献