检索结果-南通市图书馆

Tunable Reflection Bands and Defect Modes in One-Dimensional Tilted Photonic Crystal Structure

Optics and Photonics Journal 2012年第3期2卷 230-236页

作者： Sanjeev k. Srivastava Maitreyi Upadhyay suneet k. awasthi S. P. Ojha Department of Physics and Material Science and Engineering Jaypee Institute of Information Technology Deemed University Noida India Department of Physics Amity Institute of Applied Sciences Amity University Noida India Department of Physics Shobhit University Meerut India

We show theoretically that range of reflection bands and defect modes inside the band gap can be tuned by using a one-dimensional tilted photonic crystal (TPC) structure. A TPC structure is similar to the conventional PC structure with the only difference that in this case alternate layers are inclined at certain angle in the direction of periodicity of the structure. In order to obtain the reflectance spectra of the proposed structure transfer matrix method (TMM) has been employed. From the analysis of the reflectance curve, it is found that 100% reflectance range can be varied and enhanced by using TPC structure for both (TE- and TM-) polarizations. The enhancement in reflection bands increases as the tilt angle increases for both the polarizations and hence the enlarged omni-reflectance bands are obtained. Further, we study the properties of the defect modes in TPC structure by introducing the tilted defect at the different tilt angle. The results show that defect modes (tunneling modes) can be tuned at different wavelengths by changing the tilt angle of the structure without changing other parameters. Finally, the effect of variation thick.ess of defect layers on the tunneling mode has been studied for both TPC and conventional PC structure. The proposed model might be used as a tunable broadband omnidirectional reflector as well as tunable tunneling or transmission mode, which has potential applications in the field of photonics and optoelectronics.

关键词： Photonic Crystal Structure Photonic Band Gap (PBG) Omnidirectional Reflector Tilted PC Structure De-fect Modes

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

k.lvin-Helmholtz instability with mass transfer through porous media: Effect of irrotational viscous pressure

引用

Journal of Hydrodynamics 2014年第4期26卷 624-636页

作者： awasthi Muk.sh k.mar Department of Mathematics University of Petroleum and Energy Studies

This paper studies the effect of the irrotational viscous pressure on k.lvin-Helmholtz instability of the plane interface of two viscous and incompressible fluids in a fully saturated porous media with mass and heat transfers across the interface. In the earlier work. the instability of the plane interface of two viscous and streaming miscible fluids through porous media was studied by assuming that the motion and the pressure are irrotational and the viscosity enters the normal stress balance. This theory is called the viscous potential flow theory. Here, we use another irrotational theory in which the discontinuities in the irrotational tangential velocity and shear stress are eliminated in the global energy balance by considering viscous contributions of the irrotational pressure. The Darcy-Brink.an model is used in the investigation and the stability criterion is formulated in terms of a critical value of the relative velocity. It is observed that the heat and mass transfer has a destabilizing effect on the stability of the system while the irrotational shearing stresses stabilize the system.

关键词： k.lvin-Helmholtz stability porous medium irrotational viscous pressure heat and mass transfer

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Origin of Red Color of the Lower Siwalik.Palaeosols:A Micromorphological Approach

引用

Journal of Mountain Science 2009年第2期6卷 147-154页

作者： Seema Singh B.Park.sh Arun.k.awasthi Department of Earth Sciences Indian Institute of Technology RoorkeeRoorkee-247667 India Department of Earth Sciences Indian Institute of Technology RoorkeeRoorkee–247667 India

Palaeosols associated with fluvial of the Siwalik.Group are and lacustrine deposits that occur as thick.multiple pedocomplexes. The bright red color of the palaeosol beds has been earlier interpreted as a result of hot and arid palaeoclimate. However, as against this view, our investigations of the bright red palaeosol beds of the Lower Siwalik. suggest that the climate was cool and subhumid, instead of hot and arid during the deposition of these beds. Since cold climate is not very conducive to impart red coloration, further research is needed to explain the cause of these red beds. For this, the micromorphological study of soil thin sections was done which showed the presence of features such as dissolution and recrystallisation of quartz, feldspar and mica, compaction, slick.nsides, presence of calcite spars, subrounded and crack.d nature of quartz grains, microfabric, complex patterns of birefringence fabrics, pigmentary ferric oxides, thick.cutans and cementation by calcite. These features indicate that diagenesis took.place on a large scale in these sediments. The positive Eh and neutral-alk.line pH of soils also suggest that the conditions were favorable for the formation of diagenetic red beds. During burial diagenesis of sediments, the hydroxides of ferromagnesian minerals got converted into ferric oxide minerals （hematite）. During deep burial diagenesis smectite was converted into illite and the preponderance of illite over smectite with increasing depth of burial also indicates the diagenesis of sediments. Thus, the red color of the Lower Siwalik.palaeosols seems to be due mainly to the burial diagenesis of sediments and does not appear to be due to the then prevailing climatic condition.

关键词： Palaeosols C3 type vegetation diagenetic red beds calcite spars

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Upper ocean high resolution regional modeling of the Arabian Sea and Bay of Bengal

引用

Acta Oceanologica Sinica 2019年第5期38卷 32-50页

作者： Dwivedi suneet Mishra Alok.k.mar Srivastava Atul k.Banerjee Centre of Atmospheric and Ocean Studies and M N Saha Centre of Space Studies University of Allahabad

In this paper, effort is made to demonstrate the quality of high-resolution regional ocean circulation model in realistically simulating the circulation and variability properties of the northern Indian Ocean(10°S–25°N,45°–100°E) covering the Arabian Sea(AS) and Bay of Bengal(BoB). The model run using the open boundary conditions is carried out at 10 k. horizontal resolution and highest vertical resolution of 2 m in the upper *** surface and sub-surface structure of hydrographic variables(temperature and salinity) and currents is compared against the observations during 1998–2014(17 years). In particular, the seasonal variability of the sea surface temperature, sea surface salinity, and surface currents over the model domain is studied. The highresolution model's ability in correct estimation of the spatio-temporal mixed layer depth(MLD) variability of the AS and BoB is also shown. The lowest MLD values are observed during spring(March-April-May) and highest during winter(December-January-February) seasons. The maximum MLD in the AS(BoB) during December to February reaches 150 m (67 m). On the other hand, the minimum MLD in these regions during March-April-May becomes as low as 11–12 m. The influence of wind stress, net heat flux and freshwater flux on the seasonal variability of the MLD is discussed. The physical processes controlling the seasonal cycle of sea surface temperature are investigated by carrying out mixed layer heat budget analysis. It is found that air-sea fluxes play a dominant role in the seasonal evolution of sea surface temperature of the northern Indian Ocean and the contribution of horizontal advection, vertical entrainment and diffusion processes is small. The upper ocean zonal and meridional volume transport across different sections in the AS and BoB is also computed. The seasonal variability of the transports is studied in the context of monsoonal currents.

关键词： Indian Ocean modeling Arabian Sea and Bay of Bengal mixed layer depth transport

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Phishing website prediction using base and ensemble classifier techniques with cross-validation

引用

Cybersecurity 2023年第1期6卷 17-39页

作者： Anjaneya awasthi Noopur Goel Department of Computer Applications VBS Purvanchal UniversityJaunpurUPIndia

Internet or public internetwork.has become a vulnerable place nowadays as there are so many threats available for the novice or careless users because there exist many types of tools and techniques being used by notorious peo-ple on it to victimize people somehow and gain access to their precious and personal data resulting in sometimes ***,these victims suffer considerable losses in many instances due to their entrapment in such traps as hack.ng,crack.ng,data diddling,Trojan attack.,web jack.ng,salami attack.,and ***,despite the web users and the software and application developer's continuous effort to mak. and k.ep the IT infrastructure safe and secure using many techniques,including encryption,digital signatures,digital certificates,*** paper focuses on the problem of phishing to detect and predict phishing websites URLs,primary machine learning classifiers and new ensemble-based techniques are used on 2 distinct *** on a merged dataset,this study is conducted in 3 ***,they include classification using base classifiers,Ensemble classifiers,and then ensemble classifiers are tested with and without ***,their performance is analyzed,and the results are presented at last to help others use this study for their upcoming research.

关键词： Phishing Hack.ng Data diddling Machine learning Ensemble

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High-precision inverse potentials for neutron-proton scattering using piece-wise smooth Morse functions

引用

Chinese Physics C 2024年第10期48卷 201-213页

作者： Ayushi awasthi Arushi Sharma Ishwar k.nt O.S.k.S.Sastri Department of Physics and Astronomical Science Central University of Himachal PradeshDharmshala176215India

The aim of this study is to construct inverse potentials for various ℓ-channels of neutron-proton scattering using a piece-wise smooth Morse function as a *** phase equations for single-channel states and the coupled equations of multi-channel scattering are solved numerically using the 5^(th) order Runge-k.tta *** employ a piece-wise smooth reference potential comprising three Morse functions as the initial *** a machine learning-based genetic algorithm,we optimize the model parameters to minimize the mean-squared error between simulated and anticipated phase *** approach yields inverse potentials for both single and multichannel scattering,achieving convergence to a mean-squared error≤10^(-3).The resulting scattering lengths"a_(0)"and effective ranges"r"for ^(3)S_(1) and ^(1)S_(0) states,expressed as[a_(0),r],are found to be[5.445(5.424),1.770(1.760)]and[–23.741(–23.749),2.63(2.81)],respectively;these values are in excellent agreement with experimental ***,the calculated total scattering cross-sections are highly consistent with their experimental counterparts,having a percentage error of less than 1%.This computational approach can be easily extended to obtain interaction potentials for charged particle scattering.

关键词： inverse potentials neutron-proton scattering piece-wise smooth Morse function phase function method reference potential approach genetic algorithm

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A near infrared optical reflector using one-dimensional photonic crystal structure containing chalcogenide glasses

引用

Optoelectronics Letters 2010年第6期6卷 406-411页

作者： Sanjeev k.Srivastava S k.awasthi S k.Srivastava S.P.Ojha Department of Physics Amity Institute of Applied SciencesAmity University Department of Physics Jaypee Institute of Information TechnologyDeemed University Department of Physics Mahila Maha VidyalayBanaras Hindu University Department of Applied Physics Institute of TechnologyBanaras Hindu University

The reflectivity of one-dimensional chalcogenide photonic crystal(CGPC) structure with the first order reflection band in near infrared(NIR) region is theoretically ***-Se and Ge-S chalcogenide glasses are used as high and low refractive index layers respectively,because these materials have zero absorption in NIR *** transfer matrix method(TMM) is employed to calculate the reflective spectra of the proposed *** theoretical results of reflective spectra of bulk.chalcogenide materials with the composition of Sb40Se60 and Ge30S70 for 4,8,12 and 15 layers and thick.esses of 117 nm and 183 nm respectively,at normal incidence,are close agreement with the experimental ***,by increasing the number of layers of Sb40Se60 and Ge30S70,the reflection bands can be enhanced in the wider range of the NIR region for the polarization at different angles and thus the broadband omnidirectional reflector can be designed.

关键词：一维光子晶体晶体结构硫系玻璃近红外光反射镜红外区域反射光谱计算结果

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Enhancement of Photocatalytic and Antibacterial Activities of ZnO：Ag Nanopowders Through the Addition of Bamboo Charcoal： An Efficient Natural Adsorbent

引用

Acta Metallurgica Sinica(English Letters) 2017年第12期30卷 1249-1256页

作者： k. Nithiyadevi k. Ravichandran PG Research and Department of Physics AVVM Sri Pushpam College (Autonomous) Poondi Thanjavur Tamil Nadu 613 503 India Department of Physics Bharathidasan University Constituent College (Women) Orathanadu Tamil Nadu 614 625 India

This research article explains the removal of methylene blue （MB） and malachite green （MG） from aqueous solution using adsorption/photodegradation activity of ZnO：Ag/bamboo charcoal （BC） nanocomposite. In addition, the antibacterial studies of the prepared samples were tested against Staphylococcus aureus （S. aureus） Gram-positive and Escherichia coli （E. coli） Gram-negative bacteria by the well diffusion method. The ZnO：Ag/BC nanocomposite exhibits superior photocatalytic activity compared with ZnO：Ag. Remark.ble degradation efficiencies of 93.95% （MB） and 95.75% （MG） were recorded for ZnO：Ag/BC nanocomposite after 45 min. The degradation process follows a pseudo-first-order k.netics. The rate constant of ZnO：Ag/BC nanocomposite is two times greater than that of pristine ZnO nanopowder for the degradation of MB dye, while for MG dye degradation, it is three times. It is found that the ZnO：Ag/BC nanocomposite shows a higher rate of dye removal due to excellent adsorbing properties of bamboo charcoal （BC）. The ZnO：Ag/BC nanocomposite showed better antibacterial properties compared to ZnO：Ag. In this study, the samples were prepared using a simple and low-cost soft chemical route and they were characterized by optical, structural, surface morphological, antibacterial and photocatalytic properties. These characterization studies substantiate the discussions on the photocatalytic and antibacterial activities of the synthesized samples.

关键词： Bamboo charcoal Adsorbent ZnO Photocatalysis Antibacterial

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Study of temporal and spectral characteristics of the X-ray emission from solar flares

引用

Research in Astronomy and Astrophysics 2018年第10期18卷 33-48页

作者： Veena Choithani Rajmal Jain Arun k.awasthi Geetanjali Singh Sneha Chaudhari Som k.mar Sharma Dept.of Physics Sh.M.M.Patel Institute of Sciences&ResearchKadi Sarva VishwavidyalayaGandhinagar 382015India CAS k.y Laboratory of Geospace Environment Department of Geophysics and Planetary SciencesUniversity ofScience and Technology of ChinaHefei 230026China Physical Research Laboratory NavrangpuraAhmedabad 380009India

Temporal and spectral characteristics of X-ray emission from 60 flares of intensity ≥C class observed by the Solar X-ray Spectrometer （SOXS） during 2003-2011 are presented. We analyze the X-ray emission observed in four and three energy bands by the Si and Cadmium-Zinc-Telluride （CZT） detectors, respectively. The number of peak. in the intensity profile of the flares varies between 1 and 3. We find moderate correlation （R ~=0.2） between the rise time and the peak.flux of the first peak.of the flare irrespective of energy band, which is indicative of its energy-independent nature. Moreover, the magnetic field complexity of the flaring region is found to be highly anti-correlated （R = 0.61） with the rise time of the flares while positively correlated （R = 0.28） with the peak.flux of the flare. The time delay between the peak.of the X-ray emission in a given energy band and that in 25-30k.V decreases with increasing energy, suggesting conduction cooling is dominant in the lower energies. Analysis of 340 spectra from 14 flares reveals that the peak.of differential emission measure （DEM） evolution is delayed by 60-360 s relative to that of the temperature, and this time delay is inversely proportional to the peak.flux of the flare. We conclude that temporal and intensity characteristics of flares are dependent on energy as well as the magnetic field configuration of the active region.

关键词： Sun X-rays, gamma rays - Sun magnetic fields - Sun flares - Sun corona

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

MINIMAX PROGRAMMING UNDER GENERALIZED （p, r）-INVEXITY

引用

Journal of Systems Science & Complexity 2007年第4期20卷 501-508页

作者： S. k. MISHRA Shouyang WANG k. k. LAI Department of Mathematics Statistics and Computer Science College of Basic Sciences and Humanities G. B. Pant University of Agriculture and Technology Pantnagar-263 145 India Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China Department of Management Sciences City University of Hong Kong 83 Tat Chee Avenue Kowloon Hong Kong China

Minimax programming problems involving generalized （p, r）-invex functions are consid- ered. Parametric sufficient optimality conditions and duality results are established under the aforesaid assumptions on the obje... 详细信息

关键词： Duality minimax programming optimality conditions (p r)-invex functions.

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：