检索结果-南通市图书馆

Research in Astronomy and Astrophysics 2021年第3期21卷 97-106页

作者： rahul kumar thakur Shashikant Gupta rahul Nigam PK Thiruvikraman Birla Institute of Technology&Science Pilani-Hyderabad CampusIndia G D Goenka University GurgaonHaryana122103India

Different measurements of the Hubble constant(H_(0))are not consistent,and a tension between the CMB based methods and cosmic distance ladder based methods has been *** from various distance based methods are also *** aggravate the problem,the same cosmological probe(TypeⅠa SNe for instance)calibrated through different methods also provides different values of H_(0).We compare various distance ladder based methods through the already available unique data obtained from the Hubble Space Telescope(HST).Our analysis is based on parametric(t-test)as well as non-parametric statistical methods such as the Mann-Whitney U test and Kolmogorov-Smirnov *** results show that different methods provide different values of H_(0) and the differences are statistically *** biases in the calibration would not account for these differences as the data have been taken from a single telescope with a common calibration *** unknown physical effects or issues with the empirical relations of distance measurement from different probes could give rise to these differences.

关键词： Cosmology Supernovae Hubble constant

Investigating the Hubble Tension Through Hubble Parameter Data

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2023年第6期23卷 199-202页

作者： rahul kumar thakur Shashikant Gupta rahul Nigam PK Thiruvikraman Avantika University Ujjain456006India G D Goenka University GurgaonHaryana122103India Birla Institute of Technology&Science Pilani-Hyderabad CampusIndia

The Hubble constant(H_0),which represents the expansion rate of the universe,is one of the most important cosmological *** recent measurements of H0using the distance ladder methods such as type Ia supernovae are significantly greater than the CMB measurements by *** difference points to a crisis in the standard model of cosmology termed Hubble *** this work we compare different cosmological models,determine the Hubble constant and comment on the Hubble tension using the data from differential ages of *** data we use are free from systematic effects as the absolute age estimation of the galaxies is not *** apply the Bayesian approach along with the commonly used maximum likelihood method to estimate H_0 and calculate the AIC scores to compare the different cosmological *** non-flat cosmological model provides a higher value for matter density as well as the Hubble constant compared to the flatΛCDM *** AIC score is smaller for the flatΛCDM cosmology compared to the non-flat model indicating the flat model a better *** best-fit values of H_0 for both these models are 68.7±3.1 km s^(-1)Mpc^(-1)and 72.2±4km s^(-1)Mpc^(-1),*** results are consistent with the CCHP ***,the flat model result does not agree with the SH0ES result,while the non-flat result is inconsistent with the Planck value.

关键词： (cosmology:)cosmological parameters galaxies:high-redshift (stars:)supernovae:general

Single-atom catalysts boosted ultrathin film sensors

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2020年第10期39卷 1110-1112页

作者： rahul kumar Mahesh kumar Department of Electrical Engineering Indian Institute of Technology JodhpurJodhpur 342037India

Nowadays,demand for fast and accurate detection of toxic and flammable gases is increasing for human health safety,industrial process and environmental ***,gas sensor technology has become a requisite in our daily *** nanoscience and nanotechnology propel fabrication of a gas sensor at the miniaturization level for burgeoning Internet of things applications.

关键词： film nanotechnology gases

Comparison of rare earths doping(neodymium and samarium) on structural and magnetic properties of Ni-Zn-Bi nanoferrites

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第3期42卷 534-542,I0004页

作者： Shilpa Taneja Preeti thakur Dinesh kumar Yassine Slimani Atul thakur NanoLatticeX Amity University HaryanaGururam122413HaryanaIndia Nanotechnology Wing Innovative Science Research SocietyShimla177002India Centre for Nanotechnology Amity University HaryanaGururam122413HaryanaIndia Department of Biophysics Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia School of Electronics and Information Engineering Nanjing University of Information Science&TechnologyNanjing210044China

Excellent magnetic properties in ferrites are required for high-frequency applications and for wastewater treatment. Thus, the present study shows the comparison of magnetic and structural properties of Nd and Sm substituted Ni-Zn-Bi ferrites with the series Ni_(0.5)Zn_(0.5)Bi_(0.04)Nd_(x)Fe_(1.96-x)O_4(with step size 0.002)and Ni_(0.5)Zn_(0.5)Bi_(0.04)Sm_(x)Fe_(1.96-x)O_4(with step size 0.02) prepared using citrate precursor method. The impact of the substitution of rare earth ions(Nd and Sm) on magnetic properties of the synthesized samples is observed using a vibrating sample magnetometer(VSM). The saturation magnetization values enhance considerably from 52 to 58 emu/g for Nd^(3+)ions and 39 to 57 emu/g for Sm^(3+) ions, thus, making these materials magnetically hard. Further, the higher value of coercivity is also observed ranging from133 to 167 Oe for Nd^(3+)ions and 81 to 155 Oe for Sm^(3+) ions. The shape of hysteresis loops indicates a super paramagnetic and ferromagnetic behavior in the obtained samples. The squareness ratio value is<0.5, suggesting the uniaxial anisotropy of particles and hence, these ferrites are suitable for microwaveabsorbing and in permanent magnetic materials. The X-ray diffraction(XRD) pattern shows the formation of pure cubic crystallites, where, lattice parameters range from 0.840 to 0.839 nm and from 0.838to 0.839 nm for Nd^(3+)and Sm^(3+) ions substitution, respectively. The crystallite size ranges between 28.63to 29.89 nm and 18.33 to 26.23 nm, for substitution of Nd^(3+)and Sm^(3+) ions, respectively. Field emission scanning electron microscopy(FESEM) shows the formation of homogeneous grains, whereas, energy dispersive spectrometer(EDS) counts describe the purity of the samples. The Sm concentration x = 0.10has the maximum surface area with value of 42.6 m^(2)/g which proves to be having good data storage application due to high surface area. The zero-field cooled(ZFC) and field cooled(FC) data show that Nddoped Ni-Zn-Bi nano

关键词： Citrate precursor X-ray diffraction Vibrating sample magnetometer Coercivity Field emission scanning electron microscopy Rare earths

Influence of rooftop telecommunication tower on set back-step back building resting on different ground slopes

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2019年第2期18卷 351-362页

作者： Amit thakur Deepankar kumar Ashish Surender kumar Verma Civil Engineering Department Kurukshetra University Civil Engineering Department Maharaja Agrasen Institute of Technology Maharaja Agrasen University Civil Engineering Department Punjab Engineering College (Deemed to be University)

In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story nowadays. In the present study an analogy has been drawn to find out the influence of the rooftop telecommunication tower on the setback-step back building resting on ground at 20° and 30° slopes. A dynamic analysis has been performed and compared on the 4 legged angled section telecommunication tower which is located on the roof top of set back-step back building by varying positions of tower with the existing host structure built up on ground slope of 20° and 30° in both directions(X and Y).

关键词： rooftop telecommunication tower set back-step back building response spectrum analysis steel, RC frame, earthquake SAP2000

Floristic analysis and dominance pattern of sal(Shorea robusta)forests in Ranchi,Jharkhand,eastern India

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2020年第2期31卷 415-427页

作者： rahul kumar Purabi Saikia Department of Environmental Sciences Central University of JharkhandBrambeRanchi 835205JharkhandIndia

The present study describes the floristic composition and dominance pattern of sal forests in Ranchi,Jharkhand,eastern *** was studied in 47 belt transects(509100 m)that had 137 plant species(110 identified and 27 unidentified)belonging to 51 *** family Fabaceae with 17 species(8 *** to subfamily Faboideae,6 *** Caesalpinioideae and 3 *** Mimosoidieae)contributed the most to diversity,followed by Rubiaceae(8 spp.)and Euphorbiaceae(6 spp.).Tree density in sal was inversely related to species *** tree density(C 10 cm GBH)in the studied forests was 397 individuals ha-1,with a basal cover of 262.50 m2 *** plants of conservation concern are Pterocarpus marsupium Roxb,Andrographis paniculata(Burm.f.)Wall,Sterculiaurens Roxb.,Tinospora cordifolia(Willd.)Miers,and Asparagus densiflorus(Kunth)*** had the highest percentage(71%,with percentage deviation from normal life form of?25)followed by therophyte(15%,with percentage deviation?2).Observed percentage deviation from normal life form was much lower(with?2 percentage deviation)in both chamaephytes(8%)and therophytes(15%),suggesting that the studied sal forests are favorable for supporting various plants *** forest management strategies should focus on the increasing demands for different timber and non-timber forest products to conserve the plant diversity of these natural forests.

关键词： Sal forests Species richness Life form Jharkhand

Room-Temperature Gas Sensors Under Photoactivation:From Metal Oxides to 2D Materials

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2020年第11期12卷 292-328页

作者： rahul kumar Xianghong Liu Jun Zhang Mahesh kumar Department of Electrical Engineering Indian Institute of Technology JodhpurJodhpur 342037India College of Physics Center for Marine Observation and CommunicationsQingdao UniversityQingdao 266071People’s Republic of China Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjin 300071People’s Republic of China

Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap,low power consumption and portable sensors for rapidly growing Internet of things *** an important approach,light illumination has been exploited for room-temperature operation with improving gas sensor's attributes including sensitivity,speed and *** review provides an overview of the utilization of photoactivated nanomaterials in gas sensing ***,recent advances in gas sensing of some exciting different nanostructures and hybrids of metal oxide semiconductors under light illumination are ***,excellent gas sensing performance of emerging two-dimensional materialsbased sensors under light illumination is discussed in details with proposed gas sensing *** impressive features from the interaction of photons with sensing materials are elucidated in the context of modulating sensing ***,the review concludes with key and constructive insights into current and future perspectives in the light-activated nanomaterials for optoelectronic gas sensor applications.

关键词： Gas sensor Room temperature Photoactivation Metal oxide 2D materials

An Approach Using Fuzzy Sets and Boosting Techniques to Predict Liver Disease

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2021年第9期68卷 3513-3529页

作者： Pushpendra kumar Ramjeevan Singh thakur Maulana Azad National Institute of Technology BhopalIndia Central University of Jharkhand RanchiIndia

The aim of this research is to develop a mechanism to help medical practitioners predict and diagnose liver *** systems have been proposed to help medical experts by diminishing error and increasing accuracy in diagnosing and predicting *** many existing methods,a few have considered the class imbalance issues of liver disorder *** all the samples of liver disorder datasets are not useful,they do not contribute to learning about classifiers.A few samples might be redundant,which can increase the computational cost and affect the performance of the *** this paper,a model has been proposed that combines noise filter,fuzzy sets,and boosting techniques(NFFBTs)for liver disease ***,the noise filter(NF)eliminates the outliers from the minority class and removes the outlier and redundant pair from the majority ***,the fuzzy set concept is applied to handle uncertainty in ***,the AdaBoost boosting algorithm is trained with several learners viz,random forest(RF),support vector machine(SVM),logistic regression(LR),and naive Bayes(NB).The proposed NFFBT prediction system was applied to two datasets(i.e.,ILPD and MPRLPD)and found that AdaBoost with RF yielded 90.65%and 98.95%accuracy and F1 scores of 92.09%and 99.24%over ILPD and MPRLPD datasets,respectively.

关键词： Fuzzy set imbalanced data liver disease prediction machine learning noise filter

Adjusting the interfacial adhesion via surface modification to prepare high-performance fibers

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

Nano Materials Science 2023年第1期5卷 1-14页

作者： Ning Han Xiaolin Zhao Vijay kumar thakur Department of Materials Engineering KU LeuvenLeuven3001Belgium Shenzhen Automotive Research Institute Beijing Institute of TechnologyShenzhen518118GuangdongChina National Engineering Laboratory for Electric Vehicles Beijing Institute of TechnologyBeijing100081BeijingChina Biorefining and Advanced Materials Research Centre Scotland's Rural CollegeScotlandEdinburghEH93JGUK

Ultra-high molecular weight polyethylene(UHMWPE)fiber is a new kind of high-performance *** to its excellent physical and chemical characteristics,it is widely used in various ***,the surface UHMWPE fiber is smooth and demonstrates no-polar *** weak interfacial adhesion between fiber and resin seri-ously restricts the applications of UHMWPE ***,the surface modification treatments of UHMWPE fiber are used to improve the interfacial adhesion *** modified method by adding nanomaterials elu-cidates the easy fabrication,advanced equipment and proper ***,the progress of UHMWPE nanocomposite fibers prepared via adding various nanofillers are ***,the effects of other various methods on surface modification are also *** work advances the various design strategies about nano technologies on improving interfacial adhesion performance via treatment methodologies.

关键词： UHMWPE fiber Surface modification Interfacial adhesion strength Nanocomposites

CFD analysis of performance improvement of the Savonius water turbine by using an impinging jet duct design

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2019年第4期27卷 794-801页

作者： Narendra thakur Agnimitra Biswas Yogesh kumar Mithinga Basumatary Mechanical Engg.Deptt. NIT Silchar

The majority of research on water turbines focuses on design improvement of large-scale hydrokinetic turbines for power generation, which may have delayed the utilization of kinetic energy contained in rivers and canals. The aim of this paper is to improve the efficiency of a two bladed Savonius type cross-flow hydrokinetic turbine, which can be used as an energy converter to harness free-stream kinetic energy of water. An impinging jet duct design is presented for improving performance of the Savonius turbine in wind application as seen from literature. The performance of the modified turbine is evaluated using CFD software Fluent, and is compared with that of a simple two bladed Savonius water turbine and some of the prominent literature designs of the Savonius turbine. It is shown that the present design exhibits improved performance compared to the selected designs of the Savonius *** an insight of the improved performance of the modified turbine is also obtained from flow physics study.

关键词： Savonius water turbine CFD Impinging jet duct design Power coefficient Water power Flow physics