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71.
Harish Kumar Nirala Prashant K. Jain J. J. Roy M. K. Samal Puneet Tandon 《Journal of Mechanical Science and Technology》2017,31(2):599-604
Incremental sheet forming (ISF) is a recently developed manufacturing technique. In ISF, forming is done by applying deformation force through the motion of Numerically controlled (NC) single point forming tool on the clamped sheet metal blank. Single Point Incremental sheet forming (SPISF) is also known as a die-less forming process because no die is required to fabricate any component by using this process. Now a day it is widely accepted for rapid manufacturing of sheet metal components. The formability of SPISF process improves by adding some intermediate stages into it, which is known as Multi-stage SPISF (MSPISF) process. However during forming in MSPISF process because of intermediate stages stepped features are generated. This paper investigates the generation of stepped features with simulation and experimental results. An effective MSPISF strategy is proposed to remove or eliminate this generated undesirable stepped features. 相似文献
72.
K. Jagannadha Naidu Harish M. Kittur 《Analog Integrated Circuits and Signal Processing》2017,90(3):639-644
Dynamic voltage and frequency scaling (DVFS) is an efficient method to reduce the power consumption in system on-chip. To support DVFS, multiple supply voltages are generated based on different work load frequencies and currents using on-chip DC–DC voltage converter. In this paper a frequency tunable multiple output voltage switched capacitor based dc–dc converter is presented. An analog to digital converter and phase controller is used in the feedback to change the switching frequency and duty cycle of the converter. An input voltage of 1.8 V is converted to 0.6 and 0.8 V for low and high signal frequency respectively. The proposed 2-phase switched capacitor architecture with gain setting of 1:2 is designed with the 90 nm technology. An output ripple of 45 mV is observed and the maximum transient response time of the converter is 17.3 ns (= 58 MHz). 相似文献
73.
A versatile homogeneous solution growth method is developed for depositing (Zn,Mg)O:Zn2+ nanophosphor films from aqueous solutions of zinc, magnesium and triethanolamine. The effect of pH on the structural and morphology of (Zn,Mg)O:Zn2+ nanophosphor films was studied and the optimum deposition conditions have been outlined. The deposition rate of nanophosphor film at neutral pH condition was comparatively larger than in basic conditions. The as-deposited films exhibit good crystallinity with hexagonal wurtzite crystalline structure and preferably oriented along (0 0 2) plane. With time, the nanophosphor films appeared dense on the glass substrate comprising of particle sizes of 30-50 nm. Upon excitation at 326 nm, photoluminescence (PL) spectrum corresponding to deep level impurities (∼ 410-530 nm) was completely masked by the strong blue-green emission at ∼ 456 nm. The ratio of Mg to Zn was optimized for maximum PL brightness whereas the optical transmittance of the nanophosphor film decreased with increasing thickness. 相似文献
74.
Karthik Tripurari Linxiao Zhang Yang Xu David Gidony Branislav Jovanovic Harish Krishnaswamy Peter Kinget 《Analog Integrated Circuits and Signal Processing》2016,88(2):185-206
A wide-band RF channelizer architecture using the concept of 3-way iterative down-conversion is introduced. An example RF channelizer implementation splits the input spectrum of 0.6–9 GHz into 7 channels each with a 1.2 GHz bandwidth. This RF channelizer implementation has the ability of concurrently down-converting 3 channels enabling multi-Gbps aggregate data reception. It further demonstrates the ability to rapidly switch from receiving one channel to another which is crucial for rapid spectrum analysis. A prototype of the RF channelizer has been fabricated in a 65 nm standard CMOS process. A 400 Mbps (BPSK) data reception has been demonstrated by down-converting two channels concurrently. Channel switching can be as fast as 8 ns and is always faster than \(1\,\upmu s\). The chip occupies an area of 2 mm \(\times\) 1 mm and consumes an average power of 435 mW while offering a dynamic range between 58 and 63 dB. 相似文献
75.
A highly dispersive dual-concentric-core pure silica photonic crystal fiber is designed with a maximum chromatic dispersion value of about -9500 ps/(nm km) around the 1.56 microm wavelength region and a full width at half-maximum (FWHM) of 55 nm. The change in the dispersion-bandwidth product as a function of period is carefully studied by using the plane wave expansion method. The coupled mode theory matches well with the plane wave expansion method that was used to simulate the chromatic dispersion. This kind of a photonic crystal fiber structure is suitable for high-dispersion application in phased array antenna systems based on photonic crystal fiber arrays. 相似文献
76.
Harish Bahadur A. K. Srivastava R. K. Sharma Sudhir Chandra 《Nanoscale research letters》2007,2(10):469-475
We have shown that the morphological features of the sol–gel derived thin films of ZnO depend strongly on the choice of the
precursor materials. In particular, we have used zinc nitrate and zinc acetate as the precursor materials. While the films
using zinc acetate showed a smoother topography, those prepared by using zinc nitrate exhibited dendritic character. Both
types of films were found to be crystalline in nature. The crystallite dimensions were confined to the nanoscale. The crystallite
size of the nanograins in the zinc nitrate derived films has been found to be smaller than the films grown by using zinc acetate
as the precursor material. Selected area electron diffraction patterns in the case of both the precursor material has shown
the presence of different rings corresponding to different planes of hexagonal ZnO crystal structure. The results have been
discussed in terms of the fundamental considerations and basic chemistry governing the growth kinetics of these sol–gel derived
ZnO films with both the precursor materials.
相似文献
Harish BahadurEmail: |
77.
城域网和接入网发展需要的低水峰单模光纤 总被引:1,自引:1,他引:0
Shasgu kant Harish Taneja Sudipta Bhaumik Abhay Arora 《光通信研究》2005,(4):42-45
密集波分复用(DWDM)的出现扩大了长途传输网的容量,但是DWDM技术的复杂性和使用了昂贵的器件,限制了DWDM在城域网的应用.最新研制的光纤,其在整个宽工作带,包括在(1 380±3) nm上都具有低水峰.低水峰光纤与粗波分复用(CWDM)系统比用标准单模光纤(SMF)的同一系统所用的信道间隔宽33%.经过恶劣的环境试验证明,低水峰光纤具有稳定的抗氢气引起的衰减性能,可确保现场安装的低水峰光纤光缆长期可靠地工作.由于低水峰光纤具有优异的弯曲敏感性,使其与最近研制的宽带接入技术,即所谓的光纤到驻地(FTTP)完全相适应. 相似文献
78.
M.R. Savitha Prashanth K.S. Parvathy N.S. Susheelamma K.V. Harish Prashanth R.N. Tharanathan A. Cha G. Anilkumar 《Food Hydrocolloids》2006,20(8):1198-1205
Acetate, succinate and octenylsuccinate derivatives of galactomannans were prepared in anhydrous reaction conditions carried out at slightly elevated temperature (40–60 °C) using solid NaHCO3 as a mild base catalyst. Prior surface wetting of the reactants with 5% absolute ethyl alcohol gave derivatives with a higher degree of substitution, although it decreased the slurry viscosity. Use of NaHCO3 significantly minimized high pH-induced degradative reactions, and its quantitative removal later was easily accomplished by repeated washings with aqueous ethyl alcohol. FT-IR, 13C-NMR, HPSEC and SEM data provided additional structural information. These derivatives are useful as functional food ingredients. 相似文献
79.
A.B. Panda K. Harish S.V. Chaure V.S. Jadhav D. Sasmal A.K. Das I. Banerjee 《Surface & coatings technology》2010,205(5):1611-1617
TiO2 thin films have been deposited at different Ar:O2 gas ratios (20:80,70:30,50:50,and 40:60 in sccm) by rf reactive magnetron sputtering at a constant power of 200 W. The formation of TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen percentage in the films was found to increase with an increase in oxygen partial pressure during deposition. The oxygen content in the film was estimated from XPS measurement. Band gap of the films was calculated from the UV-Visible transmittance spectra. Increase in oxygen content in the films showed substantial increase in optical band gap from 2.8 eV to 3.78 eV. The Ar:O2 gas ratio was found to affect the particle size of the films determined by a transmission electron microscope (TEM). The particle size was found to be varying between 10 and 25 nm. The bactericidal efficiency of the deposited films was investigated using Escherichia coli (E. coli) cells under 1 h UV irradiation. The growth of E. coli cells was estimated through the Optical Density measurement by UV-Visible absorbance spectra. The qualitative analysis of the bactericidal efficiency of the deposited films after UV irradiation was observed through SEM. A correlation between the optical band gap, particle size and bactericidal efficiency of the TiO2 films at different argon:oxygen gas ratio has been studied. 相似文献
80.
Harish K. Patney Christina Nordlund Adam Moy Harry Rose Brent Young Michael A. Wilson 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(6):941-971
Abstract Graphite has normally been used to synthesise fullerenes and nanotubes. However, coal is a cheaper and more suitable industrial material. Because coal is a molecular solid, unlike graphite, the mechanism by which fullerene and nanotubes are formed is different. Moreover, other products such as polyaromatic hydrocarbons (PAHs) and microfibres are also formed. In this review, the mechanism of formation of fullerene and nanotubes from coal is discussed. It is shown that the pathway involved is other than through the C1 intermediate route. The influence of other elements in coal such as hydrogen, oxygen, sulfur and iron is also discussed. It appears that, hydrogen, oxygen, iron and sulfur affect the yield and type of fullerenes and nanotubes formed. 相似文献