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91.
Deepak G. Bhat Vikram A. Bedekar Stephen A. Batzer 《Machining Science and Technology》2004,8(3):341-355
This article investigates the chemical wear behavior of the ultra-hard ceramic AlMgB14 and cemented tungsten carbide for machining aerospace alloys. The chemical interdiffusivity of AlMgB14 against pure Ti and Ti-6Al-4V, in comparison with cemented carbide (WC-6%Co) cutting tool was investigated by means of diffusion couple experiments. The chemical composition profiles of various tool-workpiece combinations were determined by electron probe microanalysis after exposing the couples to 1000°C for 120 h in vacuum. Thermodynamic calculations of the chemical solubility of AlMgB14 show that the experimental diffusion results are in reasonable agreement with the predicted behavior. It is shown that AlMgB14 is significantly less soluble in titanium under static diffusion conditions, and therefore, shows considerable promise as a potential cutting tool for machining Ti alloys. 相似文献
92.
Wireless Networks - Early prediction of a forest fire is one of the critical research challenges of the wireless sensor network (WSN) to save our ecosystem. In WSN based forest fire detection... 相似文献
93.
Deepika Agrawal Muhammad Huzaif Wasim Qureshi Pooja Pincha Prateet Srivastava Sourabh Agarwal Vikram Tiwari Sudhakar Pandey 《International Journal of Communication Systems》2020,33(8)
A wireless sensor network (WSN) is a prominent technology that could assist in the fourth industrial revolution. Sensor nodes present in the WSNs are functioned by a battery. It is impossible to recharge or replace the battery, hence energy is the most important resource of WSNs. Many techniques have been devised and used over the years to conserve this scarce resource of WSNs. Clustering has turned out to be one of the most efficient methods for this purpose. This paper intends to propose an efficient technique for election of cluster heads in WSNs to increase the network lifespan. For the achievement of this task, grey wolf optimizer (GWO) has been employed. In this paper, the general GWO has been modified to cater to the specific purpose of cluster head selection in WSNs. The objective function for the proposed formulation considers average intra‐cluster distance, sink distance, residual energy, and CH balancing factor. The simulations are carried out in diverse conditions. On comparison of the proposed protocol, ie, GWO‐C protocol with some well‐known clustering protocols, the obtained results prove that the proposed protocol outperforms with respect to the consumption of the energy, throughput, and the lifespan of the network. The proposed protocol forms energy‐efficient and scalable clusters. 相似文献
94.
Bajpai Shrish Kidwai Naimur Rahman Singh Harsh Vikram Singh Amit Kumar 《Multimedia Tools and Applications》2019,78(19):27193-27209
Multimedia Tools and Applications - Hyperspectral image sensors are resource constrained and have limited on-board memory. Processing of high volume hyperspectral images pose a challenge to the... 相似文献
95.
Vikram Awate Ratnesh Tiwari A. K. Shrivastava Neha Dubey Vikas Dubey 《Journal of Materials Science: Materials in Electronics》2018,29(6):4391-4401
This review includes research papers on different method of preparation of rare earth activated Sr2SiO4 phosphors and its luminescence studies. Here in Sr2SiO4 has attracted great interest due to its special structure features, excellent physical and chemical stability. Besides, it absorbs ultraviolet radiation and emits white light when activated by different rare earth ions. Different synthesis techniques were compared and it is found that sol–gel synthesis technique is best for preparation of rare earth activated Sr2SiO4 phosphors. Literature related to characterization techniques such as X-ray diffraction techniques, scanning electron microscopy, transmission electron microscopy and other studies are also compared. Photoluminescence studies for white light emitting diode of various rare earth phosphors are compared with Sr2SiO4 phosphor reported in this review. Also some luminescence techniques such as thermoluminescence glow curve analysis and some spectroscopic parameters are also compared. The review end with some important conclusion related to rare earth activated Sr2SiO4 phosphors with proper justifications. 相似文献
96.
Kamlendra Vikram Uvaraja Ragavendran Kanak Kalita Ranjan Kumar Ghadai Xiao-Zhi Gao 《计算机、材料和连续体(英文)》2021,66(2):1771-1784
In this work, diamond-like carbon (DLC) thin film coatings are deposited on silicon substrates by using plasma-enhanced chemical vapour deposition (PECVD) technique. By varying the hydrogen (H2) flow rate, CH4−Argon (Ar) flow rate and deposition temperature (Td) as per a Box-Behnken experimental design (BBD), 15 DLC deposition experiments are carried out. The Young’s modulus (E) and the coefficient of friction (COF) for the DLCs are measured. By using a second-order polynomial regression approach, two metamodels are built for E and COF, that establish them as functions of H2 flow rate, CH4-Ar flow rate and Td. A non-dominated sorting genetic algorithm (NSGA-III) is used to obtain a set of Pareto solutions for the multi-objective optimization of E maximization and COF minimization. According to various practical scenarios, evaluation based on distance from average solution (EDAS) approach is used to identify the most feasible solutions out of the Pareto solution set. Confirmation experiments are conducted which shows the efficacy of the polynomial regression—NSGA-III—EDAS hybrid approach. The surface morphology of the DLCs deposited as per the optimal predictions is also studied by using atomic force microscopy. 相似文献
97.
We address the problem of counting emitted photons in two-photon laser scanning microscopy. Following a laser pulse, photons are emitted after exponentially distributed waiting times. Modeling the counting process is of interest because photon detectors have a dead period after a photon is detected that leads to an underestimate of the count of emitted photons. We describe a model which has a Poisson \((\alpha )\) number N of photons emitted, and a dead period \(\Delta \) that is standardized by the fluorescence time constant \(\tau (\delta = \Delta /\tau )\), and an observed count D. The estimate of \(\alpha \) determines the intensity of a single pixel in an image. We first derive the distribution of D and study its properties. We then use it to estimate \(\alpha \) and \(\delta \) simultaneously by maximum likelihood. We show that our results improve the signal-to-noise ratio, hence the quality of actual images. 相似文献
98.
Nithyanantham Thangamani Ashutosh S. Gandhi Vikram Jayaram Atul H. Chokshi 《Journal of the American Ceramic Society》2005,88(10):2696-2701
This study examined pressure consolidation of amorphous Al2 O3 –15 mol% Y2 O3 powders prepared by co-precipitation and spray pyrolysis. The two amorphous powders had similar true densities and crystallization sequences. Uniaxial hot pressing was carried out at 450°–600°C with a moderate pressure of 750 MPa. The co-precipitated powder could be hot pressed to a maximum relative density of 98% and remained amorphous. Pressure adversely affected the densification of the spray-pyrolyzed powder by favoring an early crystallization of γ-Al2 O3 phase at 580°C. Plastic deformation of the amorphous phase is believed to be responsible for the large densification of the amorphous powders. 相似文献
99.
MCM-41 materials were synthesized using alkyl(decosane, dodecyl)trimethyl ammonium bromide as structure directing surfactants. X-ray diffraction (XRD) analysis and nitrogen adsorption measurements reveal that the pores are hexagonal with tunable textural properties through the choice of surfactant and experimental condition. Poly(diphenylamine), PDPA was entrapped into the pores of MCM-41 by initial sorption of diphenylamine (DPA, monomer) in a medium (napthalein sulfonic acid) that provides self-assembling of DPA inside the pores and subsequent oxidative of polymerization with peroxydisulphate. Clear presence of an additional peak (around 9-10°) in XRD pattern for the DPA loaded MCM-41 provides evidence for self-assembled structure. Upon polymerization the self-assembly of DPA molecules resulted tubular PDPA inside the pores of MCM-41. PDPA thus formed shows different electronic property than the PDPA prepared by conventional method. XRD and FTIR spectroscopic analysis of PDPA loaded MCM-41 clearly informs that PDPA are entrapped in channels of MCM-41. 相似文献
100.
Yu‐Ping Zhang Se‐Hee Lee Kakarla Raghava Reddy Anantha Iyengar Gopalan Kwang‐Pill Lee 《应用聚合物科学杂志》2007,104(4):2743-2750
SiO2/Poly(3‐aminophenylboronic acid) (PAPBA) composites were synthesized under different experimental conditions, using ultrasonic irradiation method. Polymerization was carried out in the presence of sodium fluoride and D ‐fructose to anchor 3‐aminophenylboronic acid groups on to SiO2 surface. The SiO2/PAPBA nanocomposite prepared by NaF and D ‐fructose in the polymerization medium was found to show different morphology, electrical properties, thermal behavior and structural characterization in comparison to the nanocomposites prepared under other conditions. Ultrasonic irradiation minimizes the aggregation of nanosilica and promotes anchoring of PAPBA units over SiO2 surface. The morphology of PAPBA/ SiO2 nanocomposite was investigated by using transmission electron microscopy, UV‐visible spectroscopy; thermogravimetric analysis, Fourier transform infrared spectroscopy, and X‐ray diffraction analysis were used for characterization. Transmission electron microscope of the nanocomposites observation shows that SiO2/PAPBA composite, prepared with D ‐fructose and NaF under ultrasonication has a core–shell morphology. The thermal and crystalline properties of core‐shell SiO2/PAPBA nanocomposite was prepared via ultrasonication method is different from the SiO2/PAPBA nanocomposite prepared via conventional stirring method, in which SiO2 nanoparticles are submerged in PAPBA. Conductivity of the composite prepared via ultrasonication shows around 0.2 S/cm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2743–2750, 2007 相似文献