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An exploration of frictional and vibrational behaviors of textured deep groove ball bearing in the vicinity of requisite minimum load

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Friction 2021年第6期9卷 1749-1765页

作者： k.E.Ch.VIDYASAGAr r.k.PANDEY Dinesh kALYANASUNDArAM Center for Biomedical Engineering Indian Institute of Technology DelhiNew Delhi 110016India Department of Biomedical Engineering College of EngineeringOsmania UniversityTelangana 500007India Department of Mechanical Engineering Indian Institute of Technology DelhiNew Delhi 110016India Department of Biomedical Engineering Indian Institute of Technology DelhiNew Delhi 110016India

In case of lightly loaded radial ball bearings,failure mechanisms other than fatigue such as smearing of raceways due to increased frictional torque and vibrations often ***,attempts have been made herein for reducing the frictional torque and minimizing the vibrations of a radial deep groove ball bearing employing surface textures at the inner *** pulsed laser was used to create texture(involving micro-dimples having different dimple area density)on the inner race of test *** an in-house developed test rig,frictional torque and vibrational parameters were measured at different speeds and light loads(*** vicinity of 0.01C,where C is dynamic load capacity of radial ball bearing).Significant reduction in frictional torque and overall vibrations were found in the presence of micro-dimples on inner race at light loads irrespective of operating *** without satisfying the minimum load needed criteria for the satisfactory operation,substantial reduction in smearing marks was found on the races of textured ball bearings in comparison to conventional cases.

关键词： ball bearing textured inner race grease lubricated frictional torque vibration

Polyethylene glycol fusion repair of severed rat sciatic nerves reestablishes axonal continuity and reorganizes sensory terminal fields in the spinal cord

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Neural regeneration research 2025年第7期20卷 2095-2107页

作者： Emily A.Hibbard Liwen Zhou Cathy Z.Yang karthik Venkudusamy Yessenia Montoya Alexa Olivarez George D.Bittner Dale r.Sengelaub Program in Neuroscience Indiana UniversityBloomingtonINUSA Department of Neuroscience University of Texas at AustinAustinTXUSA

Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically *** used a plasmalemmal fusogen,polyethylene glycol(PEG),to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic *** have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration,and PEG-fused animals exhibit rapid(within 2–6 weeks)and extensive locomotor ***,our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific,i.e.,spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target *** this study,we examined the consequences of PEG-fusion for sensory axons of the sciatic *** adult male and female rats(Sprague–Dawley)received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without(Negative Control)the application of *** action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury *** success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days *** 2–42 days postoperatively,we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish ***-fusion repair reestablished axonal *** to unoperated animals,labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn,as well as inappropriate mediolateral and rostrocaudal ***,despite having intact peripheral nerves,similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repa

关键词： axotomy dorsal horn peripheral nerve injury plasticity polyethylene glycol(PEG) sciatic nerve sensory terminals wheat germ agglutinin horseradish peroxidase

Non Existence of Shear in Bianchi Type-ⅢString Cosmological Models with Bulk Viscosity and Time-Dependent A Term

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Chinese Physics Letters 2011年第2期28卷 55-57页

作者： r.k.Tiwari Sonia Sharma Department of Mathematics Govt.Model Science CollegeRewa(MP)India Department of Mathematics Rayat Polytechnic CollegeRopar(Punjab)India

We study the non existence of shear in locally rotationally symmetric Bianchi type-Ⅲstring cosmological models with bulk viscosity and variable cosmological termΛ.Exact solutions of the field equations are obtained by assuming the conditions:the bulk viscosity is proportional to the expansion scalar,ξ∝θ,expansion scalar is proportional to shear scalar,θ∝σ,and A is proportional to the Hubble *** coefficient of bulk viscosity is assumed to be a power function of mass *** corresponding physical interpretations of the cosmological solutions are also discussed.

关键词： parameter density viscosity

Steady State Creep rate Equation of Inconel 718 Superalloy

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Journal of Materials Science & Technology 1989年第2期5卷 79-84页

作者：韩雅芳 M.C.chaturvedi Institute of Aeronautical Materials Beijing China. Department of Mechanical Engineering University of Manitoba Canada.

The steady state creep rate equdtion of a nickel base superalloy Inconel 718, strengthened by coherent ordered disc-shaped bct γ^(11) phase and coherent spherical fcc γ~1 phase precipitates, has been established in the stress and temperature ranges of 620-840 MN m^(-2) and 853-943k, respecti- vely. Constant stress tensile creep tests were used to medsure the values of steady state creep rate, ε_s, and the consecutive stress reduction method was used to measure the back stress during creep deformation. The values of effective stress exponent, n_e, were detemined from the slopes of the lgε_s vs. lg(σ_a-σ_0)/G plots. The effect of grain size, d, on steady state creep rdte has been also studied in this investigation, and the grain size sensitive exponents m were detemined from the slopes of lgε_s vs. lg(b/d) plots. The creep rate equations of Inconel 718, in the above stress and temperature ranges, have been proposed to be ε_s=1.6×10^(-5)(D_1Gb/kT) (b/d )^(0.19)[(σ_a-σ_0)/G]^(1.35) in diffusional creep region, and ε_s =75(D_1Gb/kT) (b/d)^(-0.42)[(σ_a-σ_0)/G]^(5.5) in dislocation power law creep region.

关键词： Inconel 718 steady state creep creep rate equation

Anisotropic Bianchi Type-ⅠModel with a Varying A Term

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Chinese Physics Letters 2012年第3期29卷 41-43页

作者： r.k.Tiwari Divya Singh Department of Mathematics Govt.Model Science College RewaM.P.486001India

Einstein field equations with variable gravitational and cosmological constants are considered in the presence of a perfect fluid for a Bianchi type-I universe by assuming that the cosmological term is proportional to the Hubble parameter..The variation law for vacuum density was recently proposed by Schützhold on the basis of quantum field estimation in a curved expanding *** cosmological term tends asymptotically to a genuine cosmological constant and the model tends to a de Sitter *** obtain that the present universe is accelerating with a large fraction of cosmological density in the form of a cosmological term.

关键词： universe parameter gravitational

New semi-analytical approach for ice lens heaving during artificial freezing of fine-grained material

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Journal of rock Mechanics and Geotechnical Engineering 2023年第11期15卷 2994-3009页

作者： k.Niggemann r.Fuentes Institute of Geomechanics and Underground Technology RWTH Aachen UniversityAachenGermany

The calculation of frost heaving with ice lens formation is still not standard for construction projects using artificial ground freezing(AGF).In fine-grained material,ice lenses may initiate and lead to significant heaving at the ground surface,which should be considered in ***,the complex processes during ice lens formation are still not fully understood and difficult to capture in a simple *** the past,the semi-analytical approach of konrad and Morgenstern used one soil constant,the“segregation potential(SP)”.It has been mainly and most successfully applied to the heave calculation of natural-induced soil freezing in cold *** application to AGF has been so far *** solve this,a new semi-analytical approach is presented in this *** includes AGF conditions such as bottom-up freezing,temperature gradients to reach great freezing velocities,and a distinction between two freezing *** is the freezing-up state until a certain frost body thickness is reached(thermal transient state),and the other is a holding phase where the frost body thickness is kept constant(thermal quasi-steady state).To test its ability,the results are applied to another freezing direction,the top-down *** new approach is validated using two different frost-susceptible soils and,in total,50 frost heave *** the thermal transient region,where the SP is applicable,the two semi-analytical approaches are compared,showing improved performance of the current method by about 15%.

关键词： Semi-analytical approach Ice lens formation Frost heaving Bottom freezing Segregation potential Frost-susceptible soil

Lossy mode resonance-based uniform core tapered fiber optic sensor for sensitivity enhancement

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Communications in Theoretical Physics 2020年第9期72卷 104-110页

作者： Vikas keshav Walia r k Verma Department of Physics Central University of RajasthanNH-8 BandarsindriAjmer-305817RajasthanIndia Department of Physics DAV UniversityJalandhar-144012PunjabIndia

A lossy mode resonance(LMr)-supported fiber optic sensor in which a uniform fiber core is placed among two identical tapered regions, is investigated numerically. Indium tin oxide(ITO)and aluminum-doped zinc oxide(AZO) are considered as LMr active materials used to excite several lossy modes and gold and silver are used as surface plasmon resonance(SPr) active materials. In this probe design, a central uniform core coated with ITO/AZO is the active sensing region, whereas tapered regions are meant for bringing the incident angle close to the critical angle. The sensitivity of the present fiber optic bio-sensor is evaluated for first two LMrs utilizing both ITO and AZO separately, along with its variation with the taper ratio(Tr). For ITO, the maximum sensitivity values are observed to be 18.425 μm rIU^(-1)(refractive index unit)and 0.825 μm rIU^(-1), corresponding to the first and second LMrs, respectively, at a Tr of 1.6 and for AZO, equivalent values are 0.79 μm rIU^(-1) and 0.35 μm rIU^(-1), respectively, at a Tr of2.0. The results illustrate that the first LMr is more sensitive than the second LMr and the ITOcoated probe possesses greater sensitivity than the AZO-coated probe for both LMrs. Similarly,for the fiber optic SPr sensor, the maximum value of sensitivity is 5.6425 μm rIU^(-1), in the case of gold and 5.0615 μm rIU^(-1) in the case of silver, at a Tr of 1.6. Hence, the result shows that the sensor with the present fiber optic probe design has around a 3-fold enhancement in sensitivity compared with conventional SPr sensors. This study will have applications in many sensing schemes where the requirement of large sensitivity is vital.

关键词： fiber optic sensors lossy modes surface plasmons indium tin oxide aluminum-doped zinc oxide sensitivity

Effects of light availability on leaf attributes and seedling growth of four tree species in tropical dry forest

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Ecological Processes 2020年第1期9卷 17-32页

作者： Sachchidanand Tripathi rahul Bhadouria Pratap Srivastava rajkumari S.Devi ravikant chaturvedi A.S.raghubanshi Ecosystems Analysis Laboratory Department of BotanyInstitute of ScienceBanaras Hindu UniversityVaranasi 221005India Department of Botany Deen Dayal Upadhyaya CollegeUniversity of DelhiNew Delhi 110078India Natural resource Management Laboratory Department of BotanyUniversity of DelhiNew Delhi 110007India Shyama Prasad Mukherjee Post-graduate College University of AllahabadAllahabad 211013India Xishuangbanna Tropical Botanical Garden Chinese Academy of SciencesYunnan 666303China Institute of Environment and Sustainable Development(IESD) Banaras Hindu UniversityVaranasi 221005India

Background:In tropical dry forests,variation in understory light availability due to season and canopy tree density could be a governing factor in establishment and growth of tree *** with varying life history traits are expected to respond differentially to such *** investigated the response of seedlings of four tree species in a tropical day forest in relation to spatiotemporal variability of *** attempt to explore the role of leaf attributes in explaining intra-and inter-specific variations in relative growth *** study sites,each with three contrasting canopy conditions,were selected along a soil moisture *** of four tree species(viz.,Acacia catechu,Bridelia retusa,Lagerstroemia parviflora,and Shorea robusta),varying in life history traits,were monitored for seasonal variations in growth traits across canopy condition and sites for 2 ***:We observed a larger variation in leaf attributes for pioneer *** showed highest mean values for leaf dry matter content,leaf nitrogen concentration,leaf phosphorus concentration,net stomatal conductance,net photosynthetic rate,and relative growth rate in high light *** and *** demonstrated highest mean values for all the leaf attributes(except leaf dry matter content)in low light ***,intermediate values for leaf attributes were observed in *** which preferred moderate light ***:Seasonal variations in light availability at the forest floor appear to play an important role in the establishment and growth of tree seedlings in seasonal dry *** attributes can be used to explain intra-and inter-specific variation in response to light *** attributes in combinations can be used to predict relative growth rate of tree species in tropical dry environment,which apart from soil moisture is also determined by light availability due to seasonal changes and canopy tree density.

关键词： Tropical dry forest Tree seedlings Light intensity Leaf attributes Pioneer species Shade tolerance

Ascorbic acid ameliorates isoniazid-rifampicin-induced hepatocellular damage in rats

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iLIVEr 2022年第1期1卷 72-77页

作者： Shubham Patel Aman chaturvedi Nazneen Dubey Abhishek Shrivastava Aditya Ganeshpurkar Shri ram Institute of Technology-Pharmacy JabalpurIndia

Background:Phyto-constituents are widely recognized for hepatoprotective *** acid is extensively studied for the radical scavenging *** objective of the present study was to evaluate the hepatoprotective effect of ascorbic acid against isoniazid and rifampicin-induced liver damage in ***:Wistar rats were used in the present ***-cellular damage was produced by the administration of isoniazid(100 mg/kg)and rifampicin(100 mg/kg)for 21 *** acid was administered in the dose of 50,100,and 200 mg/kg body *** the end of the study,blood was collected and biochemical studies were performed to determine antioxidant ***:Ascorbic acid administration(50,100,and 200 mg/kg body weight)caused restoration of serum glutamic oxaloacetic transaminase,serum glutamic-pyruvic transaminase,and serum alkaline *** level of superoxide dismutase and catalase were also restored due to the administration of ascorbic *** was a decrement in the expression of tumor necrosis factor-α,interleukin-1β,interleukin-6,malondialdehyde and nitric ***:The outcome of the study established ascorbic acid as a notable hepatoprotective *** radical scavenging and cytokine suppression effect is the possible mechanism associated with the hepatoprotective effect of ascorbic acid.

关键词： Liver Toxicity Antitubercular Peroxidation Cytokines Ascorbic acid