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Sm^(3+)induced structural phase transition,spectral,morphological,magnetic,dielectric and impedance properties of Ni_(0.1)Cu_(0.9)Sm_(x)Fe_(2-x)O_(4) nanoferrites

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Journal of Rare Earths 2023年第11期41卷 1736-1745,I0003页

作者： K.Rajashekhar g.Vinod K.Mahesh Kumar g.harikishan Laxman Naik J Department of Physics University College of ScienceOsmania UniversityHyderabad500007TelanganaIndia Department of Physics Kamala Institute of Technology and ScienceHuzurabad505468TelanganaIndia Department of Physics CMR College of Engineering&TechnologyHyderabad501401TelanganaIndia

In the present study,rare earth samarium(Sm^(3+))substituted Ni-Cu spinel ferrites with the composition of Ni_(0.1)Cu_(0.9)Sm_(x)Fe_(2-x)O_(4)(0≤x≤0.05 in steps of 0.01)were synthesized by using the citrate induced sol-gel auto combustion technique.These ferrites'structural,optical,magnetic,and dielectric studies were carried out using X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),ultraviolet-visible(UV-vis),a vibrational sample magnetometer(VSM),and an LCR meter.The pure Ni-Cu ferrite exhibits a tetragonal structure owing to the presence of the John Tellar ion(Cu^(2+)).XRD patterns confirm that the tetragonal structure gradually transforms into the cubic spinel structure with samarium substitution.The nano-scale structures of these ferrites were confirmed by the average crystallite size(10.11-20.99 nm)derived from the X-ray diffraction patterns,and grain size(42.60-83.36 nm)assessed from FESEM photographs.The existence of elements according to their chemical composition was verified by using energy dispersive X-ray(EDX)spectra.The absorption bands(v_(1) and v_(2))detected in FTIR transmission spectra below the wavenumber of 600 cm^(-1)reveal the stretching vibrations of M-O bonds in the spinel structure at tetrahedral and octahedral locations.The band gap ene rgy obtained from UV absorption reveals the semiconducting nature of the samples.The high saturation magnetization(M_(s))is noticed at 15 K temperature for x=0.02 composition as 32.98 emu/g,while at 300 K for x=0.01composition as 27.61 emu/g.The suggested cation distribution is in good agreement with observed and predicted magnetic moment values at 300 K.The expected behavior of ferrites reveals the observed dielectric constant,loss tangent,and ac-conductivity values in the frequency range of 20 Hz-20 MHz.Cole-Cole plots confirm that the impedance contribution is attributed to grain boundaries.

关键词： Nanoferrites XRD Magnetic properties Dielectric properties Cole-cole plots Rare earths

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Sensitivity analysis of project level MOVES running emission rates for light and heavy duty vehicles

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Journal of Traffic and Transportation Engineering(English Edition) 2014年第2期1卷 81-96页

作者： Zhuo Yao Heng Wei harikishan Peragu Hao Liu Zhixia Li ART-Engines Transportation Research Laboratory College of Engineering and Applied Science University of Cincinnati Traffic Operations and Safety (TOPS) Laboratory College of Engineering University of Wisconsin-Madison

In order to understand how the uncertainties in the output can be apportioned to different sources of uncertainties in its inputs, it is critical to investigate the sensitivity of MOVES model. The MOVES model sensitivity for regional level has been well studied. However, the uncertainty analysis for project level running emissions has not been well understood. In this research, the MOVES model project level sensitivity tests on running emissions were conducted thru the analysis of vehicle specific power （VSP）, scaled tractive power （STP）, and MOVES emission rates versus speed curves. This study tested the speed, acceleration, and grade-three most critical variables for vehicle specific power for light duty vehicles and scaled tractive power for heavy duty vehicles. For the testing of STP, four regulatory classes of heavy duty vehicles including light heavy duty （LHD）, medium heavy duty （MHD）, heavy heavy duty （HHD） and bus were selected. MOVES project running emission rates were also tested for CO, PM2.5, NOx, and VOC versus the operating speeds. A Latin Hypercube （LH） sampling based on method for estimation of the ＂Sobal＂ sensitivity indices shows that the speed is the most critical variable among the three inputs for both VSP and STP. Acceleration and grades show lower response to the main effects and sensitivity indices. MOVES emission rates versus speeds curves for light duty vehicles show that highest emission occurs at lower speed range. No significant differences on emission rates among the regulatory classes of heavy duty vehicles are identified.

关键词： MOVES model sensitivity analysis project level emission rates

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城市路口过饱和机理与相应交通转移措施效应的仿真分析(英文)

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交通运输系统工程与信息 2009年第4期9卷 72-82页

作者：魏恒 PERUgU harikishan C. 辛辛那提大学土木与环境工程系美国辛辛那提城oh452210071 俄亥俄-肯塔基-印地安那三州区域规划委员会美国辛辛那提城oh45202

传统的交通信号控制优化和路口几何渠化或路口扩展在现实中可能遇到许多局限.有些路口由于土地使用的限制,实际无法采用路口几何渠化或扩展的方式来缓解路口的严重拥挤的程度.交通流量转移措施也许是一个可行的方法,但其影响因素和适时... 详细信息

传统的交通信号控制优化和路口几何渠化或路口扩展在现实中可能遇到许多局限.有些路口由于土地使用的限制,实际无法采用路口几何渠化或扩展的方式来缓解路口的严重拥挤的程度.交通流量转移措施也许是一个可行的方法,但其影响因素和适时方案很难依靠观测数据确定.结合观测数据,提出运用微观交通仿真的方法,判定需要转移的交通走向和选择路径,以降低路口延误和多选择路径旅行时间为目标,评价交通流量转移措施并估计转换量的最适应范围.研究以位于俄亥俄州辛辛那提地区的galbraith Road and Colerain Avenue(US-27)路口及其相关可选择路径作为试例,进行数据采集和分析,并运用了微观交通仿真软件VISSIM、公路通行能力分析软件HCS2000和SYNCHRO进行微观路口延误和选择路径交通模拟评价.为提高结果的可释和易解效能,研究提出交通转换比例、延误变化、选择路径旅行时间变化与服务水平变化的一体化曲线.评价结果显示了交通转移措施的可能效果.最后,讨论了实现交通转移的标志导向系统.

关键词：饱和交通交通转移多(可)选择路径信号控制路口微观交通仿真

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