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International Journal of Minerals,Metallurgy and Materials 2015年第4期22卷 389-394页

作者： s.deepak kumar A.Mandal M.Chakraborty school of Mechanical sciences Indian Institute of Technology Bhubaneswar school of Minerals Metallurgical and Materials Engineering Indian Institute of Technology Bhubaneswar

The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount of data exists on the solid fraction-temperature re- lationship in A356 alloy, information regarding the solid fraction evolution characteristics of A356-TiB2 composites is scarce. The present article establishes the temperature-solid fraction correlation in A356 alloy and A356-xTiB2 （x = 2.5wt% and 5wt%） composites using dif- ferential thermal analysis （DTA）. The DTA results indicate that the solidification characteristics of the composites exhibited a variation of 2℃ and 3℃ in liquidus temperatures and a variation of 3℃ and 5℃ in solidus temperatures with respect to the base alloy. Moreover, the eutectic growth temperature and the solid fraction（fs） vs. temperature characteristics of the composites were found to be higher than those of the base alloy. The investigation revealed that in-situ formed TiB2 particles in the molten metal introduced more nucleation sites and reduced undercooling.

关键词： particle reinforced composites aluminum alloys titanium boride casting solid fraction differential thermal analysis

轮轨接触参数的实验室模拟及轮轨冲角、蛇行运动、油水污染、真实接触面积对粘着—蠕滑性能的影响

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中国铁道科学 1984年第1期 12-35页

作者： s.kumar 钱立新美国伊利诺斯理工学院机械及空间工程系铁道部科学研究院机车车辆研究所教授副所长

本文提出了在实验室条件下轮轨关系的模拟技术及其限度。粘着系数,蠕滑,接触应力,塑流,磨耗及表面粗糙度均能在实验室进行模拟。尺寸效应在试验装置设计中占有重要地位。两种类型的实验室模拟、即赫兹模拟及几何模拟文中加以比较。IIT-G... 详细信息

本文提出了在实验室条件下轮轨关系的模拟技术及其限度。粘着系数,蠕滑,接触应力,塑流,磨耗及表面粗糙度均能在实验室进行模拟。尺寸效应在试验装置设计中占有重要地位。两种类型的实验室模拟、即赫兹模拟及几何模拟文中加以比较。IIT-GMEMD轮轨模拟试验装置也在文中加以讨论。计算了各种美国铁路货车与机车在两种模拟下的接触应力。探讨纵向粘着系数—蠕滑相互关系的试验在新接触表面及磨耗表面两种条件下进行。磨耗表面条件下进行的试验数据显示,在平均应力水平低于7031公斤/厘米~2时,上述关系与Kalker的理论相符合,当接触应力超出上述水平,则结果有所不同。试验结果还表明,改变垂直载荷得出的各条不同的粘着—蠕滑曲线都可归化为一条简单的无量纲曲线。如果实际接触面积能测量,则相应的表达式可以获得。在干燥清洁的接触表面条件下,垂直载荷及粘着值不变时,蠕滑与接触面积的乘积应是常数。表示不同冲角值(从0°到0.5°)条件下的纵向、横向与合成的粘着系数与蠕滑相互关系的一组试验曲线已获得。可以看出,随着冲角增大,通过曲线区段的纵向粘着系数会明显地下降。试验中还发现小冲角振幅的蛇行运动实际上能增加所能得到的最大粘着系数。这意味着从所需要的粘着水平角度看、车轮踏面锥度是较有利的。在轮轨间存在油、水污染时,粘着系数将大大降低,而在油污染情况下撒砂能将粘着提高到清洁干燥表面条件时的水平,但撒砂后再经受油污染,粘着最大值会降到0.15以下。

关键词：蠕滑粘着系数钢轨接触面积轮轨蛇行运动轮轨接触冲角叶栅参数实验室模拟油水

Magnetizations and magneto-transport properties of Ni-doped PrFeO_3 thin films

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Chinese Physics B 2014年第4期23卷 608-615页

作者： Feroz A.Mir s.K.sharma Ravi kumar University science Instrumentation Center University of Kashmir Instituto de Fisica Gleb Wataghin Universidade Estadual de Campinas (UNICAMP) CMsE National Institute of Technology

The present study reports the magnetizations and magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed laser ablation technique on LaA103 snbstrates. From DC M/H plots of these films, weak ferromagnetism or ferrimagnetism behaviors are observed. With Ni substitution, reduction in saturation magnetization is also seen. With Ni doping, variations in saturation field （Hs）, coercive field （Hc）, Weiss temperature （0）, and effective magnetic moment （Pelf） are seen. A small change of magnetoresitance with application of higher field is observed. Various essential parameters like density of state （Nf） at Fermi level, Mott＇s characteristic temperature （To）, and activation energy （Ea） in the presence of and in the absence of magnetic field are calculated. The present observed magnetic properties are related to the change of Fe-O bond length （causing an overlap between the oxygen p orbital and iron d orbital） and the deviation of the Fe-O-Fe angle from 180~. Reduction of magnetic domain after Ni doping is also explored to explain the present observed magnetic behavior of the system. The influence of doping on various transport properties in these thin films indicates a distortion in the lattice structure and single particle band width, owing to stress-induced reduction in unit cell volume.

关键词： thin films magnetization ferromagnetism ferrimagnetism magneto-transport and distortion

Analytical modeling of subthreshold current and subthreshold swing of Gaussiandoped strained-si-on-insulator MOsFETs

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Journal of semiconductors 2014年第8期35卷 52-59页

作者： Gopal Rawat sanjay kumar Ekta Goel Mirgender kumar sarvesh Dubey s.Jit Department of Electronics Engineering Indian Institute of Technology (BHU) Varanasi India Faculty of Electronics and Communication Engineering Shri Ramswaroop Memorial University Lucknow-Deva Road India

This paper presents the analytical modeling of subthreshold current and subthreshold swing of short- channel fully-depleted （FD） strained-si-on-insulator （ssOI） MOsFETs having vertical Gaussian-like doping pro- file in the channel. The subthreshold current and subthreshold swing have been derived using the parabolic approx- imation method. In addition to the effect of strain on silicon layer, various other device parameters such as channel length （L）, gate-oxide thickness （tox）, strained-si channel thickness （ts_si）, peak doping concentration （Np）, project range （Rp） and straggle （op） of the Gaussian profile have been considered while predicting the device characteris- tics. The present work may help to overcome the degradation in subthreshold characteristics with strain engineering. These subthreshold current and swing models provide valuable information for strained-si MOsFET design. Ac- curacy of the proposed models is verified using the commercially available ATLAsTM, a two-dimensional （2D） device simulator from sILVACO.

关键词： strained-si-on-insulator (ssOI) Poisson's solution short-channel-effects

spectroscopy,decay properties and Regge trajectories of the B and B_s mesons

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Chinese Physics C 2017年第9期41卷 8-18页

作者： Virendrasinh Kher Naynes.kumar Devlani Ajay kumar Rai Applied Physics Department PolytechnicThe M.S.University of Baroda Department of Applied Physics Sardar Vallabhbhai National Institute of Technology

A Gaussian wave function is used for detailed study of the mass spectra of the B and Bs mesons using a Cornell potential incorporated with （1/m） correction in the potential energy term and expansion of the kinetic energy term up to （p10） for relativistic correction of the Hamiltonian. The predicted excited states for the B and Bs mesons are in very good agreement with results obtained by experiment. We assign B2（5747） and Bs2（5840） as the 1^3p2 state, B1（5721） and Bs1（5830） as the 1P1 state, B0（5732） as the 1^3P0 state, Bs1（5850） as the 1P1 state and B（5970） as the 23s1 state. We investigate the Regge trajectories in the （J,M2） and （nr,M2） planes with their corresponding parameters. The branching ratios for leptonic and radiative-leptonic decays are estimated for the B and Bs mesons. Our results are in good agreement with experimental observations as well as outcomes of other theoretical models.

关键词： potential model mass spectrum decay constant Regge trajectories

Experimental Evaluation of a Multistage Reciprocating Evaporative Cooler Performance for Varied Climatic Conditions

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Journal of Thermal science 2023年第4期32卷 1523-1535页

作者： sampath sURANJAN sALINs s.V.KOTA REDDY shiva kumar school of Engineering and IT Manipal Academy of Higher EducationDubai CampusDubaiPO 345050UAE Mechanical Engineering Department VIT-AP UniversityAmaravatiAndra Pradesh52223India Department of Mechanical and Manufacturing Engineering Manipal Institute of TechnologyManipal Academy of Higher EducationManipal576104India

Current system focuses on design&construction of a multistage reciprocating evaporative cooling test *** packings that are used will undergo the reciprocating action,powered by the cam follower mechanism maintained at an actual rotation *** dry bulb temperature&humidity values are varied to replicate the varying climatic conditions,and the output parameters such as cooling load,evaporation rate(ER),humidification efficiency(HE),coefficient of performance(COP)are *** results showed that as inlet humidity raises,the performance of system *** the rise in the camshaft speed or packing velocity,there is an upsurge in the performance until a cam speed of 10 r/min or packing velocity of 0.083 m/s and with further increases in the value,overall performance *** system gave a maximum COP,ER,and HE equal to 3.80,73.87%,and 0.53 g/kg respectively.A rise in the inlet air temperature yielded a maximum change in dry bulb temperature of 8.2℃.Overall,results indicated that evaporative cooling is more effective in arid climates than the cold and humid *** quality test is performed to measure CO_(2),Total Volatile Organic Compound(TVOC),and Formaldehyde(HCHO),and it is found that humidified air entering the defined space is of excellent quality.

关键词： multistage humidifier evaporative cooling reciprocating packing humidification efficiency

发展减少能源消费所带来的环境影响:能源效率在清洁生产中的作用

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生态毒理学报 2001年第3期23卷 52-56页

作者： s.kumar C.Visvanathan school of Environmen Resources and Development Asian Institute of Technology PO Box 4 Klong Luang 12 120 Pathumthnai Thailand(kumar@ ait. Ac. Th) School of Environmen Resources and Development Asian Institute of Technology PO Box 4 Klong Luang 12 120 Pathumthnai Thailand(kumar@ ait. Ac. Th)

工业界提高能源效率、削减污染的活动起始于1970年代.但这些活动通常是各自独立地开展的.合理使用能源的要求以及要求采取预防性措施削减污染促使人们发起并推广清洁生产.本文讨论了把清洁生产能力建设方法结合到专业培训课程、学术课... 详细信息

工业界提高能源效率、削减污染的活动起始于1970年代.但这些活动通常是各自独立地开展的.合理使用能源的要求以及要求采取预防性措施削减污染促使人们发起并推广清洁生产.本文讨论了把清洁生产能力建设方法结合到专业培训课程、学术课程之中的方式.

关键词：能源消费环境影响能源效率清洁生产

Optimization of fused deposition modeling process parameters using a fuzzy inference system coupled with Taguchi philosophy

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Advances in Manufacturing 2017年第3期5卷 231-242页

作者： saroj kumar Padhi Ranjeet kumar sahu s. s. Mahapatra Harish Chandra Das Anoop kumar sood Brundaban Patro A. K. Mondal Department of Mechanical Engineering Institute of Technical Education and Research Siksha 'O' AnusandhanUniversity Bhubaneswar 751030 India Department of Mechanical Engineering SRM UniversityKattankulathur 603203 India Department of Mechanical Engineering National Institute ofTechnology Rourkela 769008 India Department of Manufacturing Engineering National Instituteof Foundry and Forging Technology Ranchi 834003 India Department of Mechanical Engineering National Institute of Technology Warangal 506004 India

Fused deposition modeling （FDM） is an additive manufacturing technique used to fabricate intricate parts in 3D, within the shortest possible time without using tools, dies, fixtures, or human intervention. This article empiri- cally reports the effects of the process parameters, i.e., the layer thickness, raster angle, raster width, air gap, part orientation, and their interactions on the accuracy of the length, width, and thicknes, of acrylonitrile-butadiene- styrene （ABsP 400） parts fabricated using the FDM tech- nique. It was found that contraction prevailed along the directions of the length and width, whereas the thickness increased from the desired value of the fabricated part. Optimum parameter settings to minimize the responses, such as the change in length, width, and thickness of the test specimen, have been determined using Taguchi＇s parameter design. Because Taguchi＇s philosophy fails to obtain uniform optimal factor settings for each response, in this study, a fuzzy inference system combined with the Taguchi philosophy has been adopted to generate a single response from three responses, to reach the specific target values with the overall optimum factor level settings. Further, Taguchi and artificial neural network predictive models are also presented in this study for an accuracy evaluation within the dimensions of the FDM fabricated parts, subjected to various operating conditions. The pre- dicted values obtained from both models are in good agreement with the values from the experiment data, with mean absolute percentage errors of 3.16 and 0.15, respectively. Finally, the confirmatory test results showed an improvement in the multi-response performance index of 0.454 when using the optimal FDM parameters over the initial values.

关键词： Fused deposition modeling (FDM) ·Dimensional accuracy · Fuzzy logic · Performance characteristic · Multi-response performance index (MRPI)Artificial neural network (ANN)

Brain-derived neurotrophic factor signaling in the neuromuscular junction during developmental axonal competition and synapse elimination

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Neural Regeneration Research 2025年第2期20卷 394-401页

作者： Josep Tomàs Víctor Cilleros-Mañé Laia Just-Borràs Marta Balanyà-segura Aleksandra Polishchuk Laura Nadal Marta Tomàs Carolina silvera-simón Manel M.santafé Maria A.Lanuza Unitat d’Histologia i Neurobiologia(UHNeurob) Facultat de Medicina i Ciències de la SalutUniversitat Rovira i VirgiliReusSpain

During the development of the nervous system,there is an overproduction of neurons and *** competition between neighboring nerve endings and synapses performing different activity levels leads to their elimination or *** have extensively studied the involvement of the brain-derived neurotrophic factor-Tropomyosin-related kinase B receptor neurotrophic retrograde pathway,at the neuromuscular junction,in the axonal development and synapse elimination process versus the synapse *** purpose of this review is to describe the neurotrophic influence on developmental synapse elimination,in relation to other molecular pathways that we and others have found to regulate this *** particular,we summarize our published results based on transmitter release analysis and axonal counts to show the different involvement of the presynaptic acetylcholine muscarinic autoreceptors,coupled to downstream serine-threonine protein kinases A and C(PKA and PKC)and voltage-gated calcium channels,at different nerve endings in developmental *** dynamic changes that occur simultaneously in several nerve terminals and synapses converge across a postsynaptic site,influence each other,and require careful studies to individualize the mechanisms of specific *** describe an activity-dependent balance(related to the extent of transmitter release)between the presynaptic muscarinic subtypes and the neurotrophin-mediated TrkB/p75NTR pathways that can influence the timing and fate of the competitive interactions between the different axon *** downstream displacement of the PKA/PKC activity ratio to lower values,both in competing nerve terminals and at postsynaptic sites,plays a relevant role in controlling the elimination of supernumerary ***,calcium entry through L-and P/Q-subtypes of voltage-gated calcium channels(both channels are present,together with the N-type channel in developing nerve terminals)contributes to red

关键词： acetylcholine release adenosine receptors axonal competition brain-derived neurotrophic factor calcium channels motor end-plate muscarinic acetylcholine receptors postnatal synapse elimination serine kinases tropomyosin-related kinase receptorB

Weaning of nasal CPAP in preterm infants:who,when and how?a systematic review of the literature

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World Journal of Pediatrics 2015年第1期11卷 7-13页

作者： shaili Amatya deepa Rastogi Alok Bhutada shantanu Rastogi Division of Neonatology Maimonides Infants&Children's Hospital4802 Tenth AveK-113Brooklyn NY 11219USA Children's Hospital at Montefiore Albert Einstein College of MedicineBronxNY 10467USA

Background:There is increased use of early nasal continuous positive airway pressure(NCPAP)to manage respiratory distress in preterm infants but optimal methods and factors associated with successful wean are not well defined.A systematic review was performed to define the corected gestational age(CGA),weight to wean NCPAP and the methods associated with successful weaning of the NCPAP among preterm infants,along with factors affecting ***:searches were made of PubMed using the keywords-NCPAP,CPAP,weaning,withdrawal,preterm,and infants from its inception to January 1st,2014,for studies in all languages but limited to *** reviews(including cross references)were also *** included all randomized and quasi-randomized controlled trials where preterm neonates were randomized to different NCPAP weaning *** of CGA,weight and methods used for weaning NCPAP were extracted along with factors which affect its ***:seven studies met the search *** successful wean was at 32 to 33 weeks CGA and at 1600 *** different methods were used for weaning were sudden,gradual pressure wean and gradual graded time off *** for readiness,success and failure to wean were *** affecting successful weaning were intubation,anemia,infection and gastro-esophageal ***:The successful wean was at 32 to 33 weeks CGA and 1600 *** for readiness,success and failure to wean are well *** weaning may be associated with a shorter weaning *** trials are needed comparing weaning methods using defined criteria for readiness and success of NCPAP wean and stratify the results by gestational age and birth weight.

关键词： continuous positive airway pressure infants preterm systematic review weaning