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101.
Dittrick S Balla VK Bose S Bandyopadhyay A 《Materials science & engineering. C, Materials for biological applications》2011,31(8):1832-1835
This first generation investigation evaluates the in vitro tribological performance of laser-processed Ta coatings on Ti for load-bearing implant applications. Linear reciprocating wear tests in simulated body fluid showed one order of magnitude less wear rate, of the order of 10(-4)mm(3)(N.m)(-1), for Ta coatings compared to Ti. Our results demonstrate that Ta coatings can potentially minimize the early-stage bone-implant interface micro-motion induced wear debris generation due to their excellent bioactivity comparable to that of hydroxyapatite (HA), high wear resistance and toughness compared to popular HA coatings. 相似文献
102.
Adnan Ahmed Andrew J. Neely Krishna Shankar 《Metallurgical and Materials Transactions A》2011,42(3):795-815
This article studies the influence of nanometric (n-SiCp) and micrometric-scale SiC particulates (μ-SiCp) on the tensile properties of the Al 7075 alloy. The unreinforced Al and its composites were synthesized using the powder
metallurgy (P/M) route and were tested uniaxially in tension at both room and elevated temperatures. Aging behavior was studied
to observe any effect of the reinforcement on the aging kinetics and hardness of the composites. X-ray diffraction was performed
to determine the crystal structures of the raw materials and any reaction phase formed in the composites. The n-SiCp were not dispersed uniformly in the Al matrix and clustered mainly at the grain boundaries. The stiffness of the composites
increased and the ductility decreased with an increase in the volume fraction of the n-SiCp. The n-SiCp proved to be a better reinforcement than the traditional μ-SiCp in terms of imparting higher ductility to the composite. Fractography and microscopy using optical, scanning electron, and
transmission electron microscopes were performed for failure and microstructural analysis of all the materials. At room temperature,
the fracture altered from ductile in the unreinforced Al to brittle in the composites. At an elevated temperature, the fracture
mechanism transformed from brittle to ductile rupture in the composites. 相似文献
103.
Jeena Jose Karippal H. N. Narasimha Murthy K. S. Rai M. Krishna M. Sreejith 《Journal of Materials Engineering and Performance》2010,19(8):1143-1149
This paper presents the experimental results of dispersing multiwalled carbon nanotubes (MWNTs) into epoxy (space grade structural adhesive) nanocomposites using co-rotating twin screw extrusion process. Two sets of specimens were prepared; set 1 with ultrasonication for predispersing MWNT before extrusion and set 2 direct dispersion of MWNT in the extruder. MWNT was loaded up to 8 vol.% in both the sets. The specimens were characterized for room temperature volume and surface resistivities as per ASTM D257 using Keithley Model 6517 and for thermal conductivity in the temperature range ?50 to 150 °C as per ASTM E 1530 using Thermal Conductivity Instrument (TCI) 2022 SX211. The volume resistivity of sets 1 and 2 decreased to an extent of 1011 and 109 respectively. The surface resistivity drop was of the order of 109 for both the sets. These drops corresponded to the maximum MWNT loading of 8 vol.%. Electrical conductivity values of the specimens were fitted into the Power Law Model to evaluate the critical exponent. Both sets 1 and 2 showed increase in thermal conductivity with increase in temperature in the testing range. Thermal conductivity increased with increase in filler loading and the maximum increase was 60% at 150 °C in case of 8 vol.% MWNT nanocomposites for set 1. The corresponding value for the set 2 was 25%. Thermal conductivity values were predicted using Lewis Nielson model. DSC of the specimens showed increase in glass transition temperature with increase in filler loading. The dispersion of the nanofillers was studied using SEM and the surface morphology using AFM. 相似文献
104.
Multi-Criteria Decision Making Approach for Watershed Prioritization Using Analytic Hierarchy Process Technique and GIS 总被引:4,自引:1,他引:3
V. M. Chowdary D. Chakraborthy A. Jeyaram Y. V. N. Krishna Murthy J. R. Sharma V. K. Dadhwal 《Water Resources Management》2013,27(10):3555-3571
Watershed prioritization based on the natural resources and physical processes involves locating critical areas of erosion, which produce maximum sediment yield to take up conservation activities on priority basis. The present study was taken up with a specific objective of prioritization of micro-watersheds using Multi-Criteria Decision Approach – Analytic Hierarchy Process (AHP) based SYI model (AHPSYI) under GIS environment for a case study area of Mayurakshi watershed in India. This method basically uses information of Potential Erosion Index (PEI) and Sediment Delivery Ratio (SDR), indicative of transport capacity. In the present study, sediment delivery factors viz., topography, vegetation cover, proximity to water courses and soil were translated into GIS layers and integrated using Boolean conditions to create a data layer of spatially distributed SDIs’ across the watershed. For assessment of PEI, important watershed parameters viz., land use/land cover, soil, slope, and drainage density maps were integrated in the GIS environment using Weighted Linear Combination method (WLC) by assigning weights to themes and ranks to features of individual theme using AHP technique. A comparison between AHPSYI based sub watershed prioritization map with that of prioritization map based on the observed sediment yield data revealed that about 78 % of the area showed concurrence. Thus, it can be inferred that the watershed prioritization based on only thematic layers can be dependable to maximum extent. Subsequently, proposed approach was adopted for prioritization of the study area at micro watershed scale, where area under high and very high categories together constitutes around 33 % of the study area. Around 100 micro-watersheds out of 276 watersheds are under moderate to very high category respectively, signifying the need for watershed management. 相似文献
105.
R. Venkata Ramana B. Krishna S. R. Kumar N. G. Pandey 《Water Resources Management》2013,27(10):3697-3711
Rainfall is one of the most significant parameters in a hydrological model. Several models have been developed to analyze and predict the rainfall forecast. In recent years, wavelet techniques have been widely applied to various water resources research because of their time-frequency representation. In this paper an attempt has been made to find an alternative method for rainfall prediction by combining the wavelet technique with Artificial Neural Network (ANN). The wavelet and ANN models have been applied to monthly rainfall data of Darjeeling rain gauge station. The calibration and validation performance of the models is evaluated with appropriate statistical methods. The results of monthly rainfall series modeling indicate that the performances of wavelet neural network models are more effective than the ANN models. 相似文献
106.
Constructivist Management of Knowledge,Communication and Enterprise Innovation: Lessons from Indian Experience 总被引:1,自引:1,他引:0
Prime movers of enterprise innovation are inside the organisation. The enterprise NIIT, studied in this paper, tells us how
elicitation and recognition of knowledge and its contents set an enterprise on the move. Recognised knowledge is actionable.
Each act of recognition is an addition to knowledge content, and such additions took place in NIIT through acts of communications
and self-searching. These contents form a large collage that cannot be strewn into a single novelistic episode. Perspectives
and context, motives and suggestions render to each member of the enterprise different disjoint appearances of knowledge.
There are thus many knowledge systems and multiple narrations, each with small episode-like finality. Enterprise innovation
is achieved not through any grand episodic integration of all knowledge contents, but by constructively eliciting further
new contents of knowledge, and encouraging acts of communications and discourses on this new knowledge. Constructive management
of knowledge and communication towards enterprise innovation has thus been defined. Through such constructive management,
NIIT enabled itself innovationally and empowered its members in eliciting knowledge and acting communicatively. A critical
feature of knowledge work is that it requires multidisciplinary expertise and mutual learning in order to achieve a complex
synthesis of highly specialised state-of-the-art technologies and knowledge domains. A convivial work culture and a culture
of communicative acts enable sharing of the non-informatised yet recognised contents of knowledge. 相似文献
107.
The controlled assembly of nanoparticles in thin film form on solid supports, both as monolayers and as superlattice structures, is a problem of considerable topical interest. Among the many interactions used to program the assembly of nanoparticles, electrostatic forces are particularly interesting for many reasons. This Account deals with assembling surface-modified nanoparticles in thin film form using electrostatic interactions at the air-water interface and in thermally evaporated lipid films. The generality of the electrostatic assembly protocol is demonstrated in the immobilization of DNA and proteins in lipid films. 相似文献
108.
Krishna C. Mandal Sung Hoon Kang Michael Choi Job Bello Lili Zheng Hui Zhang Michael Groza Utpal N. Roy Arnold Burger Gerald E. Jellison David E. Holcomb Gomez W. Wright Joseph A. Williams 《Journal of Electronic Materials》2006,35(6):1251-1256
High-quality, large (10 cm long and 2.5 cm diameter), nuclear spectrometer grade Cd0.9Zn0.1Te (CZT) single crystals have been grown by a controlled vertical Bridgman technique using in-house zone refined precursor
materials (Cd, Zn, and Te). A state-of-the-art computer model, multizone adaptive scheme for transport and phase-change processes
(MASTRAP), is used to model heat and mass transfer in the Bridgman growth system and to predict the stress distribution in
the as-grown CZT crystal and optimize the thermal profile. The model accounts for heat transfer in the multiphase system,
convection in the melt, and interface dynamics. The grown semi-insulating (SI) CZT crystals have demonstrated promising results
for high-resolution room-temperature radiation detectors due to their high dark resistivity (ρ≈2.8 × 1011 Θ cm), good charge-transport properties [electron and hole mobility-life-time product, μτe≈(2–5)×10−3 and μτh≈(3–5)×10−5 respectively, and low cost of production. Spectroscopic ellipsometry and optical transmission measurements were carried out
on the grown CZT crystals using two-modulator generalized ellipsometry (2-MGE). The refractive index n and extinction coefficient
k were determined by mathematically eliminating the ∼3-nm surface roughness layer. Nuclear detection measurements on the single-element
CZT detectors with 241Am and 137Cs clearly detected 59.6 and 662 keV energies with energy resolution (FWHM) of 2.4 keV (4.0%) and 9.2 keV (1.4%), respectively. 相似文献
109.
Modeling Multithreaded Applications Using Petri Nets 总被引:2,自引:0,他引:2
Krishna M. Kavi Alireza Moshtaghi Deng-jyi Chen 《International journal of parallel programming》2002,30(5):353-371
Since most modern computing systems contain multiple processing elements, applications are relying on multithreaded programming techniques that allow a program to execute multiple tasks concurrently to take advantage of the processing capabilities. Multithreaded programs are more difficult to design and test because of the nondeterministic execution orders and synchronization among the threads. Different approaches can be used to test Multithreaded Applications. In our approach we use Petri nets to represent the key elements of interactions among threads to identify potential problems such as race conditions, lost signals, and deadlocks. A tool called C2Petri has been developed which converts C-Pthreads programs to the equivalent Petri net model. This tool helps verification of Pthread-based programs. At present the tool has limited capabilities and we hope to expand the capabilities of our tool in the near future. 相似文献
110.
Digital speckle photography combined with TV shearography is developed for precise measurement of the magnitude of the shear field in a linear shear configuration. As an application the method is implemented to determine the slope-change variations of a three-dimensional object with TV shearography in which the shear magnitude is obtained with the digital speckle photography technique. 相似文献