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boulder-induced form roughness and skin shear stresses in a gravel-bed stream

Journal of Mountain Science 2024年第1期21卷 346-360页

作者： das Ratul DATTA Akash Civil Engineering Department National Institute of Technology AgartalaAgartala-799046India

boulder spacing in mountain rivers and near-wake flow zones within the boulder array is very useful for fish habitat and growth of aquatic *** present study aims to investigate how the boulder array and spacing influence the near-bed flow structures in a gravel-bed *** are staggered over a gravel-bed stream with three different inter-boulder spacing namely(a)large(b)medium and(c)small *** acoustic Doppler velocimeter was used for flow measurements in a rectangular channel and the results were compared with those acquired from numerical *** time-averaged velocity profiles at the near-wake flow zones of boulders experience maximum flow retardation which is an outcome of the boulder-induced form *** ratio of velocity differences associated to form and skin roughness and its positive magnitude reveals the dominance of form roughness closest to the *** roughness computed is 1.75 to 2 times higher than the skin roughness at the near-wake flow *** particular,the collective immobile boulders placed at different inter-boulder spacings developed high and low bed shear stresses closest to the *** low bed shear stresses characterised by a secondary peak developed at the trough location of the boulders is attributed to the skin shear ***,the spatial averaging of time-averaged flow quantities gives additional impetus to present an improved illustration of fluid shear *** formation of form-induced shear stress is estimated to be 17%to 23%of doubleaveraged Reynolds shear stress and partially compensates for the damping of time-averaged Reynolds shear stress in the interfacial *** quadrant analysis of spatial velocity fluctuations depicts that the form-induced shear stresses are dominant in the interfacial sub-layer and have no significance above the gravel-bed surface.

关键词： Array of boulders Near wake flow zones Velocity distributions Skin roughness Form induced shear stresses

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Optimization of flotation variables for the recovery of hematite particles from bHQ ore

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International Journal of Minerals,Metallurgy and Materials 2013年第7期20卷 605-611页

作者： Swagat S. Rath Hrushikesh Sahoo b. das CSIR-Institute of Minerals and Materials Technology Bhubaneswar 751 013 India

The technology for beneficiation of banded iron ores containing low iron value is a challenging task due to increasing demand of quality iron ore in India. A flotation process has been developed to treat one such ore, namely banded hematite quartzite （bHQ） containing 41.8wt% Fe and 41.5wt% SiO2,by using oleic acid, methyl isobutyl carbinol （MIbC）, and sodium silicate as the collector, frother, and dispersant, respectively. The relative effects of these variables have been evaluated in half-normal plots and Pareto charts using central composite rotatable design. A quadratic response model has been developed for both Fe grade and recovery and optimized within the experimental range. The optimum reagent dosages are found to be as follows： collector concentration of 243.58 g/t, dispersant concentration of 195.67 g/t, pH 8.69, and conditioning time of 4.8 min to achieve the maximum Fe grade of 64.25% with 67.33% recovery. The predictions of the model with regard to iron grade and recovery are in good agreement with the experimental results.

关键词： hematite iron ore treatment flotation metal recovery design of experiments mathematical models opti-mization

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Magnetic and flotation studies of banded hematite quartzite (bHQ) ore for the production of pellet grade concentrate

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 675-682页

作者： b. das b.K.Mishra S. Prakash S.K.das P.S.R.Reddy S.I.Angadi Institute of Minerals and Materials Technology Council of Scientific & Industrial Research (CSIR)

To identify and establish beneficiation techniques for banded hematite quartzite （bHQ） iron ore, a comprehensive research on bHQ ore treatment was carried out. The bHQ ore was assayed as 38.9wt% Fe, 42.5wt% SiO2, and 1.0wt% Al2O3. In this ore, hematite and quartz are present as the major mineral phases where goethite, martite, and magnetite are present in small amounts. The liberation of hematite particles can be enhanced to about 82% by reducing the particle size to below 63 μm. The rejection of silica particles can be obtained by magnetic and flotation separation techniques. Overall, the bHQ ore can be enriched to 65.3wt% Fe at 61.9% iron recovery. A flowsheet has been suggested for the commercial exploitation of the bHQ ore.

关键词： hematite beneficiation magnetic separation flotation pelletizing

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Separation of hematite from banded hematite jasper(bHJ) by magnetic coating

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Journal of Central South University 2015年第2期22卷 437-444页

作者： Subhashree Singh H.Sahoo S.S.Rath b.b.Palei b.das CSIR-Institute of Minerals and Materials Technology

The separation of iron oxide from banded hematite jasper(bHJ) assaying 47.8% Fe, 25.6% Si O2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite,jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade bHJ iron ore under appropriate conditions.

关键词：磁性涂层赤铁矿磁分离碧玉带状低品位矿铁回收率涂覆材料

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Anisotropic strange quark star in Finch-Skea geometry and its maximum mass for non-zero strange quark mass(m_(s)≠0)

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Chinese Physics C 2023年第5期47卷 195-210页

作者： b.das K.b.Goswami A.Saha P.K.Chattopadhyay Department of Physics Coochbehar Panchanan Barma UniversityVivekananda StreetCoochbehar 736101West BengalIndia Department of Physics Alipurduar CollegeAlipurduar 736122West BengalIndia

A class of relativistic astrophysical compact objects is analyzed in the modified Finch-Skea geometry described by the MIT bag model equation of state of interior matter,p=1/3(ρ-4b),where b is known as the bag constant.b plays an important role in determining the physical features and structure of strange *** consider the finite mass of the strange quark(m_(s)≠0) and study its effects on the stability of quark matter inside a *** note that the inclusion of strange quark mass affects the gross properties of the stellar configuration,such as maximum mass,surface red-shift,and the radius of strange quark *** apply our model physically,we consider three compact objects,namely,(ⅰ) VELA X-1,(ⅱ) 4U 1820-30,and(ⅲ) PSR J 1903+327,which are thought to be strange *** range of b is restricted from 57.55 to bstable(MeV/fm3),for which strange matter might be stable relative to iron(^(56)Fe).However,we also observe that metastable and unstable strange matter depend on b and *** energy conditions hold well in this *** in terms of the Lagrangian perturbation of radial pressure is studied in this paper.

关键词： compact star strange star anisotropy MIT EoS strange quark mass

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Effect of in ovo feeding of xylobiose and xylotriose on plasma immunoglobulin, cecal metabolites production, microbial ecology, and metabolic pathways in broiler chickens

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Journal of Animal Science and biotechnology 2024年第4期15卷 1578-1589页

作者： Razib das Pravin Mishra birendra Mishra Rajesh Jha Department of Human Nutrition Food and Animal SciencesCollege of Tropical Agriculture and Human ResourcesUniversity of Hawaii at ManoaHonoluluHI 96822USA

background Dietary supplementation of xylooligosac charides(XOS) has been found to influence gut health by manipulating cecal microbiota and producing microbe-origin *** no study investigated and compared the effect of in ovo feeding of xylobiose(XOS2) and xy lotriose(XOS3) in *** study investigated the effect of in ovo feeding of these XOS compounds on post-hatch gut health parameters in chickens.A total of 144 fertilized chicken eggs were divided into three groups:a) non-injected control(CON),b) XOS2,and c) *** the 17^(th) embryonic day,the eggs of the XOS2 and XOS3 groups were injected with 3 mg of XOS2 and XOS3 diluted in 0.5 mL of 0.85% normal saline through the amniotic *** hatching,the chicks were raised for 21 *** was collected on d 14 to measure plasma *** digests were collected for measuring short-chain fatty acids(SCFA) on d 14 and 21,and for microbial ecology and microbial metabolic pathway analyses on d 7 and *** The results were considered significantly different at Pbut significant differences on d ***;the SCFA concentrations were lower in the XOS3 than in the CON group on d *** cecal metagenomics data showed that the abundance of the family Clostridiaceae significantly decreased on d 7,and the abundance of the family Oscillospiraceae increased on d 21 in the XOS2 compared to the *** was a reduction in the relative abundance of genus Clostridium sense stricto 1 in the XOS2 compared to the CON on d 7 and the genus Ruminococcus,torques in both XOS2 and XOS3 groups compared to the CON on d *** XOS2 and XOS3 groups reduced the genes for chondroitin sulfate degradation Ⅰ and L-histidine degradation Ⅰpathways,which contribute to improved gut health,respectivelyc in the micr

关键词： broiler In ovo Metagenomics Prebiotic Xylooligosaccharides

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DEFICIENT CUbIC SPLINES WITH AVERAGE SLOPE MATCHING

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Analysis in Theory and Applications 2005年第1期21卷 1-14页

作者： V.b.das A.Kumar R.D.University India R.D.University India

We obtain a deficient cubic spline function which matches the functions with certain area matching oner a greater mesh intervals, and also provides a greater flexibility in replacing area matching as interpolation. We... 详细信息

关键词： deficient cubic splines area slope interpolation

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Scalable orthogonal delay-division multiplexed OEO artificial neural network trained for TI-ADC equalization

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Photonics Research 2024年第1期12卷 85-105页

作者： ANDREA ZAZZI ARKA DIPTA das LUKAS HüSSEN RENATO NEGRA JEREMY WITZENS Institute of Integrated Photonics RWTH Aachen University52074 AachenGermany Chair of High-Frequency Electronics RWTH Aachen University52074 AachenGermany

We propose a new signaling scheme for on-chip optical-electrical-optical artificial neural networks that utilizes orthogonal delay-division multiplexing and pilot-tone-based self-homodyne *** scheme offers a more efficient scaling of the optical power budget with increasing network *** simulations,based on220 nm silicon-on-insulator silicon photonics technology,suggest that the network can support 31×31 neurons,with 961 links and freely programmable weights,using a single 500 m W optical comb and a signal-to-noise ratio of 21.3 d b per ***,it features a low sensitivity to temperature fluctuations,ensuring that it can be operated outside of a laboratory *** demonstrate the network’s effectiveness in nonlinear equalization tasks by training it to equalize a time-interleaved analog-to-digital converter(ADC)architecture,achieving an effective number of bits over 4 over the entire 75 GHz ADC *** anticipate that this network architecture will enable broadband and low latency nonlinear signal processing in practical settings such as ultra-broadband data converters and real-time control systems.

关键词： network delay artificial

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Hybrid ion/electron interfacial regulation stabilizes the cobalt/oxygen redox of ultrahigh-voltage lithium cobalt oxide for fast-charging cyclability

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Science bulletin 2024年第13期69卷 2071-2079页

作者： Zhihong bi Anping Zhang Gongrui Wang Cong Dong Pratteek das Xiaoyu Shi Zhong-Shuai Wu State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China Dalian National Laboratory of Clean Energy Chinese Academy of SciencesDalian 116023China

High-voltage and fast-charging LiCoO_(2)(LCO)is key to high-energy/power-density Li-ion ***,unstable surface structure and unfavorable electronic/ionic conductivity severely hinder its high-voltage fast-charging ***,we construct a Li/Na-b-Mg-Si-O-F-rich mixed ion/electron interface network on the 4.65 V LCO electrode to enhance its rate capability and long-term cycling ***,the resulting artificial hybrid conductive network enhances the reversible conversion of Co^(3+)/^(4+)/O_(2)/nredox by the interfacial ion–electron cooperation and suppresses interface side reactions,inducing an ultrathin yet compact cathode electrolyte ***,the derived near-surface Na+/Mg2+/Si^(4+)-pillared local intercalation structure greatly promotes the Li^(+)diffusion around the 4.55 V phase transition and stabilizes the cathode ***,excellent 3 C(1 C=274 mA g1)fast charging performance is demonstrated with 73.8%capacity retention over 1000 *** findings shed new insights to the fundamental mechanism of interfacial ion/electron synergy in stabilizing and enhancing fast-charging cathode materials.

关键词： High-voltage Fast-charging LiCoO_(2) Interfacial ion-electron cooperation Local intercalation

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MXene-based Elastomer Mimetic StretchableSensors: Design, Properties, and Applications

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Nano-Micro Letters 2024年第7期16卷 295-342页

作者： Poushali das Parham Khoshbakht Marvi Sayan Ganguly Xiaowu(Shirley)Tang bo Wang Seshasai Srinivasan Amin Reza Rajabzadeh Andreas Rosenkranz School of biomedical Engineering McMaster University1280 Main Street WestHamiltonON L8S 4L8Canada Department of Chemistry and Waterloo Institute for Nanotechnology(WIN) University of Waterloo200 University Ave WestWaterlooONCanada Centre for Eye and Vision Research(CEVR) 17W Hong Kong Science ParkShatinHong KongPeople’s Republic of China Chair of Functional Materials Department of Materials Science and EngineeringSaarland UniversitySaarbruckenGermany W booth School of Engineering Practice and Technology McMaster University1280 Main Street WestHamiltonON L8S 4L7Canada Department for Chemical Engineering Biotechnology and MaterialsUniversity of ChileSantiagoChile

Flexible sensors based on MXene-polymer composites are highly prospective for next-generation wearable electronics used in human-machine *** of the motivating factors behind the progress of flexible sensors is the steady arrival of new conductive ***,a new family of 2D nanomaterials,have been draw-ing attention since the last decade due to their high electronic conduc-tivity,processability,mechanical robustness and chemical *** this review,we encompass the fabrication of MXene-based polymeric nanocomposites,their structure-property relationship,and applications in the flexible sensor ***,our discussion is not only lim-ited to sensor design,their mechanism,and various modes of sensing platform,but also their future perspective and market throughout the *** our article,we intend to fortify the bond between flexible matrices and MXenes thus promoting the swift advancement of flexible MXene-sensors for wearable technologies.

关键词： Flexible sensor 2D nanomaterials MXene Wearable and conductive Applications

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